Visual-discrimination deficits after lesions of the centrifugal visual system in pigeons (Columba livia).

The effects of bilateral lesions of the centrifugal visual system (CVS) on the visual-discrimination capacity were studied in pigeons. Three different behavioral experiments, each testing different aspects of visual analysis, were performed. In the first two experiments, a grain-grit discrimination task and a visual-acuity determination, stimuli were presented in the frontal binocular visual field. A third experiment investigated the early detection of slow moving objects, introduced into the monocular lateral visual field. After bilateral lesions in the nucleus isthmo-opticus (ION) and in the ectopic nucleus isthmo-opticus (EION), a multiple linear regression analysis was employed to correlate the postoperative performance in all three tasks with the amount of structure loss within ION and EION. Deficits in the grain-grit discrimination procedure were a function of the ION lesion extent and did not depend on EION damage. Thus, these two structures could be functionally differentiated for the first time. Neither the ION nor the EION seems to be involved in visual-acuity performance or the early detection of large shadows moving forward through the visual field. Our data support the hypothesis that the CVS is involved in pecking and food selection among static stimuli at a short viewing distance in ground-feeding birds such as pigeons and chickens.


Effect of strabismus on the development of vernier acuity and grating acuity in monkeys.

The effect of experimental strabismus on the development of vernier acuity and grating acuity was studied in Macaca nemestrina monkeys. Six monkeys were studied longitudinally beginning near 10 days after birth. Four of the six monkeys developed amblyopia. As is true for human strabismic amblyopes, the deficit in vernier acuity was larger than the deficit in grating acuity in the amblyopic monkeys. The developmental data reveal that this differential disruption of vernier acuity can be understood as a result of a slowed developmental process associated with amblyopia.


Oculomotor localization relies on a damped representation of saccadic eye displacement in human and nonhuman primates.

The oculomotor system has long been thought to rely on an accurate representation of eye displacement or position in a successful attempt to reconcile a stationary target's retinal instability (caused by motion of the eyes) with its corresponding spatial invariance. This is in stark contrast to perceptual localization, which has been shown to rely on a sluggish representation of eye displacement, achieving only partial compensation for the retinal displacement caused by saccadic eye movements. Recent studies, however, have begun to case doubt on the belief that the oculomotor system possess a signal of eye displacement superior to that of the perceptual system. To verify this, five humans and one monkey (Macaca nemestrina) served as subjects in this study of oculomotor localization abilities. Subjects were instructed to make eye movements, as accurately as possible, to the locations of three successive visual stimuli. Presentation of the third stimulus (2-ms duration) was timed so that it fell before, during, or after the subject's saccade from the first stimulus to the second. Localization errors in each subject (human and nonhuman) were consistent with the hypothesis that the oculomotor system has access to only a damped representation of eye displacement--a representation similar to that found in perceptual localization studies.


A coupled network for parasol but not midget ganglion cells in the primate retina.

Intracellular injections of Neurobiotin were used to determine whether the major ganglion cell classes of the macaque monkey retina, the magnocellular-projecting parasol, and the parvocellular-projecting midget cells showed evidence of cellular coupling similar to that recently described for cat retinal ganglion cells. Ganglion cells were labeled with the fluorescent dye acridine orange in an in vitro, isolated retina preparation and were selectively targeted for intracellular injection under direct microscopic control. The macaque midget cells, like the beta cells of the cat's retina, showed no evidence of tracer coupling when injected with Neurobiotin. By contrast, Neurobiotin-filled parasol cells, like cat alpha cells, showed a distinct pattern of tracer coupling to each other (homotypic coupling) and to amacrine cells (heterotypic coupling). In instances of homotypic coupling, the injected parasol cell was surrounded by a regular array of 3-6 neighboring parasol cells. The somata and proximal dendrites of these tracer-coupled cells were lightly labeled and appeared to costratify with the injected cell. Analysis of the nearest-neighbor distances for the parasol cell clusters showed that dendritic-field overlap remained constant as dendritic-field size increased from 100-400 microns in diameter. At least two amacrine cell types showed tracer coupling to parasol cells. One amacrine type had a small soma and thin, sparsely branching dendrites that extended for 1-2 mm in the inner plexiform layer. A second amacrine type had a relatively large soma, thick main dendrites, and distinct, axon-like processes that extended for at least 2-3 mm in the inner plexiform layer. The main dendrites of the large amacrine cells were closely apposed to the dendrites of parasol cells and may be the site of Neurobiotin transfer between the two cell types. We suggest that the tracer coupling between neighboring parasol cells takes place indirectly via the dendrites of the large amacrine cells and provides a mechanism, absent in midget cells, for increasing parasol cell receptive-field size and luminance contrast sensitivity.


Binocular depth perception following early experience with interocular torsional disparity.

The relationship between the behavioral and physiological consequences of rearing with optically induced cyclotropia was assessed. Beginning at the age of 4 weeks, kittens wore goggles that rotated the visual field in opposite directions in each eye for several hours each day over a period of several weeks. The amounts of interocular rotation were 0 deg (control), 16 deg, and 32 deg. Subsequently, they were tested to determine their monocular and binocular depth thresholds and, in some cases, visual acuity. In several kittens recordings were also made from the visual cortex. Binocular performance of all kittens in the 0-deg condition and three out of six kittens in the 16-deg condition was comparable to, although slightly lower than, that of normally reared kittens. In contrast, none of the 32-deg kittens showed any evidence of the binocular superiority that would suggest the presence of stereopsis. Extracellular unit recordings from the visual cortex confirmed our earlier results with goggle-reared kittens. In 16-deg kittens, the distribution of the cells' preferred interocular disparities (IOD) in receptive-field orientation showed a compensating shift so that the mean matched the experienced rotational disparity. In the 32-deg kittens, binocularity was greatly disrupted and there was no compensatory shift in the IOD distribution. Two 32-deg kittens were afforded 3 years of subsequent normal visual experience. Both the behavioral and the physiological findings were unaffected by normal visual exposure in adulthood. Control measurements of acuity indicated that any deficits in depth perception were not due to reduced spatial-resolution abilities. The data indicate that the kitten visual system is able to maintain functional binocularity sufficient to subserve a moderate level of stereoacuity with interocular rotations of up to at least 16 deg.


Contacts of dopaminergic interplexiform cells in the outer retina of the blue acara.

Dopaminergic interplexiform cells in the retina of the blue acara were investigated using an antiserum against tyrosine hydroxylase and PAP visualization. In whole-mount preparations, we observed a homogeneous distribution of cell bodies throughout the retina without any indication of regional specialization. At the fine and ultrastructural level, we studied the morphology of labeled telodendria within the outer plexiform layer. Apart from contacts with horizontal cell perikarya and bipolar cell dendrites, we observed direct contacts, mostly in the form of close appositions, with cone pedicles and rod spherules. Quantitative evaluation and reconstruction of serial sections showed that all cone pedicles and most rod terminals were approached in this way. The dopaminergic pathway terminating on horizontal cells and photoreceptors is discussed with respect to the localization of dopamine receptors in the outer retina, and the control of adaptive changes such as retinomotor movements, spinule formation, and horizontal cell coupling.


The effect of dopamine depletion on light-evoked and circadian retinomotor movements in the teleost retina.

The retinae of lower vertebrates undergo a number of structural changes during light adaptation, including the photomechanical contraction of cone myoids and the dispersion of melanin granules within the epithelial pigment. Since the application of dopamine to dark-adapted retinae is known to produce morphological changes that are characteristic of light adaptation, dopamine is accepted as a casual mechanism for such retinomotor movements. However, we report here that in the teleost fish, Aequidens pulcher, the intraocular injection of 6-hydroxydopamine (6-OHDA), a substance known to destroy dopaminergic retinal cells, has no effect on the triggering of light-adaptive retinomotor movements of the cones and epithelial pigment and only slightly depresses the final level of light adaptation reached. Furthermore, the retina continues to show circadian retinomotor changes even after 48 h in continual darkness that are similar in both control and 6-OHDA injected fish. Biochemical assay and microscopic examination showed that 6-OHDA had destroyed dopaminergic retinal cells. We conclude, therefore, that although a dopaminergic mechanism is probably involved in the control of light-induced retinomotor movements, it cannot be the only control mechanism, nor can it be the cause of circadian retinomotor migrations. Interestingly, 6-OHDA injected eyes never reached full retinomotor dark adaptation, suggesting that dopamine has a role to play in the retina's response to darkness.


Subcortical connections of visual areas MST and FST in macaques.

To examine the subcortical connections of the medial superior temporal and fundus of the superior temporal visual areas (MST and FST, respectively), we injected anterograde and retrograde tracers into 16 physiologically identified sites within the two areas in seven macaque monkeys. The subcortical connections of MST and FST were found to be very similar. Both areas were found to be reciprocally connected with the pulvinar, mainly with its medial subdivision, and with the claustrum. Nonreciprocal projections from both MST and FST were consistently found in the striatum (caudate and putamen), reticular nucleus of the thalamus, and the pontine nuclei. The labeled terminals in the pons were in the dorsolateral, lateral, dorsal, and peduncular nuclei. Additional nonreciprocal projections were found in one MST and one FST case to the nucleus of the optic tract, and, in one FST case, to the lateral terminal nucleus. Finally, three cases showed a nonreciprocal projection to FST from the basal forebrain. The subcortical structures containing label following MST and FST injections were largely the same as those labeled after injections of the middle temporal visual area (MT), but the label within each structure after MST and FST injections was more widespread than that from MT, overlapping the distribution of label that has been reported after injections of parietal visual areas. This finding is consistent with the known contributions of MST and FST to the functions of parietal cortex, such as eye-movement control.


Visual orienting in schizophrenia.

Patients with schizophrenia demonstrate a variety of attentional impairments which have proven difficult to relate to specific neural systems. Posner et al. (1988) reported an asymmetric slowing of right visual field orienting in schizophrenia similar to that observed in patients with parietal lesions. We examined the visual orienting performance of 19 patients and controls using two different versions of the Posner paradigm. In overall ANOVAs we found main effects of group, cue condition, and delay interval. However, we did not observe any main effect of visual field or interactions involving visual field. There was some evidence of an asymmetric cost of invalid cues similar to those reported by Posner et al. The bulk of data suggests bilateral attentional deficits.


The circadian component of spinule dynamics in teleost retinal horizontal cells is dependent on the dopaminergic system.

During the light phase of a light/dark cycle, dendrites of teleost cone horizontal cells display numerous finger-like projections, called spinules, which are formed at dawn and degraded at dusk, and are thought to be involved in chromatic feedback processes. We have studied the oscillations of these spinules during a normal light/dark cycle and during 48 h of constant darkness in two groups of strongly rhythmic, diurnal fish, Aequidens pulcher. In one group the retinal dopaminergic system had been destroyed by the application of 6-OHDA, while in the other (control) group, the dopaminergic system was intact. In control fish, oscillations of spinule numbers were observed under both normal and constant dark conditions, indicating the presence of a robust circadian rhythm. However, spinule dynamics were severely affected by the absence of retinal dopamine. During the normal light phase, the number of spinules in 6-OHDA injected retinae was strongly reduced, and throughout continual darkness, spinule formation was almost completely suppressed. These results indicate that dopamine is essential for both light-evoked and circadian spinule formation; furthermore, we conclude that there is no circadian oscillator within horizontal cells controlling the formation of spinules.


Effects of serotonergic agonists and antagonists on ganglion cells in the goldfish retina.

Extracellular recordings were made from the isolated goldfish retina during superfusion with various serotonergic agonists and antagonists to determine the effects of these drugs on the maintained activity and response properties of the ganglion cells. Superfusion of the retina with serotonin (25-500 microM) increased the maintained activity of OFF-center ganglion cells and decreased the maintained activity of ON-center ganglion cells. In addition, serotonin also attenuated the excitatory responses to annular stimuli, suggesting a decrease in the strength of surround input to the ganglion cells. The effects of serotonin on OFF-center ganglion cells were mimicked by the nonselective 5-HT1 agonist 5-MeOT and the 5-HT1A receptor agonist 8-OH-DPAT, while only 5-MeOT mimicked the action of serotonin on ON-center ganglion cells. The effects of exogenously applied serotonin on the ganglion cells could be blocked by the mixed 5-HT1/5-HT2 receptor antagonist methysergide but not by the 5-HT2 receptor antagonist mianserin or the dopamine receptor antagonist haloperidol. These results support previous anatomical and biochemical evidence that serotonin functions in a neurotransmitter or neuromodulatory role in the teleost retina and suggest that serotonin may be involved in modulating the maintained activity and surround input to the ganglion cells. The results also indicate that two different types of receptors may mediate the actions of serotonin in the ON and OFF pathways, respectively.


Serotonin synthesis and accumulation by neurons of the anuran retina.

Serotonin-synthesizing and serotonin-accumulating neurons were studied in the retinas of Xenopus laevis and Bufo marinus. All previously identified cell types exhibiting serotonin-like immunoreactivity (SLI) were labeled by intravitreal injection of 5,7-dihydroxytryptamine (5,7-DHT). They included two amacrine cell types (large and small) in both species, and one bipolar cell type in Xenopus. Incubation of retinas in culture medium in the ambient light reduced SLI in amacrine cells and enhanced the labeling in bipolar cells. After incubation, some photoreceptor cell bodies and large numbers of outer segments also displayed SLI in both species. Incubation with the serotonin-uptake inhibitor, fluoxetine, reduced immunolabeling in bipolar cells and outer segments to the level in the untreated retinas. Both large SLI and 5,7-DHT-accumulating amacrine cells in Xenopus and Bufo were labeled with an antibody raised against phenylalanine hydroxylase (PH), which binds to tryptophan 5-hydroxylase, one of the synthesizing enzymes for serotonin. Small SLI and 5,7-DHT-accumulating amacrine cells in both species represented two populations, one with and the other without PH-like immunoreactivity (PH-LI). The anti-PH antibody failed to label any SLI or 5,7-DHT-accumulating bipolar cells in Xenopus. These observations indicate that all large and some small SLI amacrine cells in the retinas of Xenopus and Bufo synthesize serotonin, while other small SLI amacrine, bipolar and photoreceptor cell bodies, and outer segments only accumulate serotonin.


Localization of actin filaments and microtubules in the cells of the Limulus lateral and ventral eyes.

The ommatidia of the lateral eye of the horseshoe crab, Limulus polyphemus, undergo rhythmic changes in structure that are driven by diurnal lighting and efferent neural activity from a circadian clock in the brain. This study uses cytochemical probes to investigate the cytoskeletal elements mediating these responses and to develop models for their control. Antibodies to actin and phallodin, a specific F-actin probe, label the rhabdom of lateral eye ommatidia, the cone cells of the ommatidial aperture, the ommatidial sheath, and the peripheral regions of the photoreceptor (retinular cell) cytoplasm. These probes also label the rhabdomere of ventral photoreceptors. Antibodies to tubulin label the eccentric cell dendrite and soma in each lateral eye ommatidium, the cone cells of the aperture, and the peripheral retinular cell cytoplasm. Models are proposed for the cytoskeletal mechanisms involved in controlling aperture and rhabdom shape, pigment movement, and shedding of rhabdomeral membrane.


Gender differences in the clinical expression of schizophrenia.

Gender differences have been reported for a variety of clinical measures in patients with schizophrenia. Clinical characterization may be helpful in identifying symptom clusters which can then be linked to underlying brain function. In this study 74 men and 33 women meeting DSM-IIIR criteria for schizophrenia were studied off medication and rated on measures of symptom type and severity, as well as premorbid and current function. Men were more severely impaired in ratings of negative symptoms, while positive symptoms were not significantly different. There were also differences in premorbid and current functioning, with women manifesting better social functioning than men.


Enkephalin-immunoreactive ganglion cells in the pigeon retina.

A small number of enkephalin-like immunoreactive cells were observed in the ganglion cell layer of the pigeon retina. Many of these neurons were identified as ganglion cells, since they were retrogradely labeled after injections of fluorescent latex microspheres in the contralateral optic tectum. These ganglion cells were mainly distributed in the inferior retina, and their soma sizes ranged from 12-26 microns in the largest axis. The enkephalin-containing ganglion cells appear to represent only a very small percentage of the ganglion cells projecting to the optic tectum (less than 0.1%). Two to 7 weeks after removal of the neural retina, there was an almost complete elimination of an enkephalin-like immunoreactive plexus in layer 3 of the contralateral, rostrodorsal optic tectum. These data provide evidence for the existence of a population of enkephalinergic retinal ganglion cells with projections to the optic tectum.


Auditory hallucinations in women and men.

The total population of a community schizophrenia registry sample yielded information about the relative lifetime frequency of hallucinations in women and men. Whereas hallucinations in non-auditory modalities were equally distributed between the two sexes, auditory hallucinations were significantly more common in women. These results will be considered in relation to the existing literature on hallucinations and gender.


Visual thresholds in albino and pigmented rats.

Albino rats have recently been reported to have increment thresholds against dim backgrounds that are two log units higher than those of pigmented rats. We, on the other hand, have failed to confirm these differences using electroretinogram b-waves and pupillary light reflexes. This paper reports on experiments using evoked potentials from cortex and colliculus and single-unit recordings from colliculus. We recorded visual-evoked potentials from cortex and superior colliculus in the strains of albino (CD) and pigmented (Long-Evans) rats used in the earlier studies. Thresholds were determined on eight fully dark-adapted animals by extrapolating intensity-response curves to the point at which there was zero evoked potential. The average dark-adapted threshold for the visual-evoked cortical potential was -5.6 log cd/m2 in pigmented and -5.80 log cd/m2 in albino animals. The average dark-adapted threshold for the superior colliculus evoked response was -5.54 log cd/m2 in pigmented and -5.84 log cd/m2 in albinos. The differences were not statistically significant. On the same apparatus, the average absolute threshold for three human observers was -5.3 log cd/m2, a value close to the rat dark-adapted thresholds. Thus, visual-evoked cortical potentials and superior collicular evoked potentials failed to confirm the report of higher dark-adapted thresholds for albinos. In addition, we find that single units in superior colliculus in the albino rat respond to very dim flashes.


Pre-frontal structural and functional deficits associated with individual differences in schizotypal personality.

This study tests the hypothesis that pre-frontal deficits underlie schizotypal personality in the normal population. Personality measures assessing features of DSM-IIIR schizotypal personality disorder (SPD) were related to left and right pre-frontal brain area assessed by magnetic resonance imaging (MRI), and neuropsychological measures of pre-frontal functioning (Wisconsin Card Sorting Task, WCST) in a group of non-institutionalized, unmedicated normal subjects. High schizotypal scores were significantly associated with reduced pre-frontal area and more WCST perseveration errors; conversely no relationships were observed between these pre-frontal measures and measures of psychosis-proneness unrelated to SPD traits. Pre-frontal structural findings were not found to be mediated by temporal lobe and posterior cortical structural deficits, height, weight, socio-economic status, education level and sex differences, while pre-frontal functional findings were not mediated by non-prefrontal cognitive ability. These findings of pre-frontal structural and functional deficits associated with schizotypal personality provide some initial converging support for a pre-frontal explanation of individual differences in schizotypal personality in the general population.


Area 17 lesions deactivate area MT in owl monkeys.

The middle temporal visual area, MT, is one of three major targets of the primary visual cortex, area 17, in primates. We assessed the contribution of area 17 connections to the responsiveness of area MT neurons to visual stimuli by first mapping the representation of the visual hemifield in MT of anesthetized owl monkeys with microelectrodes, ablating an electrophysiologically mapped part of area 17, and then immediately remapping MT. Before the lesions, neurons at recording sites throughout MT responded vigorously to moving slits of light and other visual stimuli. In addition, the relationship of receptive fields to recording sites revealed a systematic representation of the contralateral visual hemifield in MT, as reported previously for owl monkeys and other primates. The immediate effect of removing part of the retinotopic map in area 17 by gentle aspiration was to selectively deactivate the corresponding part of the visuotopic map in MT. Lesions of dorsomedial area 17 representing central and paracentral vision of the lower visual quadrant deactivated neurons in caudomedial MT formerly having receptive fields in the central and paracentral lower visual quadrant. Most neurons at recording sites throughout other parts of MT had normal levels of responsiveness to visual stimuli, and receptive-field locations that closely matched those before the lesion. However, neurons at a few sites along the margin of the deactivated zone of cortex had receptive fields that were slightly displaced from the region of vision affected by the lesion into other parts of the visual field, suggesting some degree of plasticity in the visual hemifield representation in MT.(ABSTRACT TRUNCATED AT 250 WORDS)


One-year results of excimer laser photorefractive keratectomy for myopia.

Excimer laser photorefractive keratectomy for the correction of myopia is presently under investigation in the United States by the Food and Drug Administration (FDA). The Phase II-B FDA study is being conducted on 75 normally sighted myopic eyes utilizing three currently available excimer lasers. This report presents the 1-year results on 12 myopic eyes treated with the VISX excimer laser system at the Ellis Eye Center at Cedars-Sinai Medical Center in Los Angeles under the Phase II-B FDA protocol. Twelve eyes of 12 patients with myopia between -1.75 and -5.00 diopters underwent 193 nm argon/fluoride excimer laser photorefractive keratectomy. The epithelium was mechanically removed, and fixation was accomplished with a suction ring which provided nitrogen flow across the corneal surface. The computer controlled corneal ablations were 5.00 mm in diameter and were accomplished with an iris diaphragm closing from large to small. The preoperative spherical equivalent myopia was -3.50 D (SD = 1.02) and the postoperative myopia was -0.25 (SD = 0.48). Eleven of the 12 patients achieved an uncorrected visual acuity of 20/30 or better and were corrected to within +/- 0.50 D of emmetropia. All corneas demonstrated a mild reticular subepithelial haze which was barely visible at 1 year. There were no vision-threatening complications and none of the eyes experienced a loss of best corrected visual acuity. In this small trial, the excimer laser appears to be capable of accurately changing the refractive power of the cornea for the correction of myopia with minimal side effects. Only when larger numbers of patients undergo the procedure will we be able to determine the safety and efficacy of photorefractive keratectomy as a refractive surgical procedure.


Photokeratitis from subablative 193-nanometer excimer laser radiation.

Photokeratitis is a side effect of UV light exposure whereby the corneal epithelium is photochemically injured in a time delayed fashion. UV light exposure in the far ultraviolet wavelength range has not previously been observed. This study addresses the concern of photokeratitis from subablative 193-nanometer excimer laser light. Dutch belted rabbit corneas were irradiated with subablative 193-nanometer excimer laser light over a wide range of total energy exposures, and examined by slit lamp biomicroscope for signs of photokeratitis. Photokeratitis was identified by epithelial haze and stippling, and rose bengal and fluorescein staining at varied time intervals between 1/2 to 26 hours post exposure. At threshold energy exposures of 1.0 to 1.5 J/cm2, an immediate superficial epithelial haze was seen which disappeared within several hours. At higher energy exposures of 10 J/cm2, a delayed photokeratitis with deep rose bengal and even fluorescein staining was seen. This latter delayed photokeratitis resembles that of longer UV wavelengths and is due to excimer laser fluorescence, whereas the former is a direct response of the 193-nanometer light. The percentage of excimer laser light undergoing fluorescence is calculated as less than 1%. The potential side effects and hazards of scattered 193-nanometer radiation during excimer laser surgery are extremely limited because of the shorter penetration depth of direct excimer radiation and the minimal fluorescent emission of longer UV wavelengths for energy exposures within the realm of clinical use.


Combined transverse and interrupted radial keratotomy for compound myopic astigmatism.

A variety of patterns of keratotomy are used to correct naturally occurring astigmatism. We evaluated straight transverse incisions with interrupted radial incisions (jump radials). In 32 human eyes with naturally occurring astigmatism, we used straight transverse incisions with interrupted radial incisions, with or without additional radial keratotomy, to correct compound myopic astigmatism. The range of preoperative refractive astigmatism was 1.00 to 3.50 D. The mean follow-up time was 15 months (range, 12 to 18 months). The average surgically corrected astigmatism was 1.55 +/- 0.29 D. Eighty-seven percent of the eyes achieved less than 1.00 D of astigmatism, and the remaining four eyes retained 1.00 to 1.25 D of astigmatism. Combined transverse and interrupted radial incisions are effective in correcting naturally occurring astigmatism.


Report on psychosocial findings and satisfaction among patients 1 year after excimer laser photorefractive keratectomy.

The first 26 patients who underwent photorefractive keratectomy with an excimer laser in our clinic with a 1-year follow up voluntarily answered a questionnaire. It was intended to get information about their social status, motivation, expectations, and satisfaction with myopic excimer laser photorefractive keratectomy. All patients wore corrective lenses before surgery; 74% wore no optical correction after the photorefractive keratectomy. "To improve general vision" was the highest ranked motivation while "looking better" was only of minor importance. Seventy-two percent reported that their subjective vision became better; 28% felt that it didn't change, but none reported deterioration of subjective vision. Seventy-five percent of the patients reported improvement of their lifestyle after surgery, whereas 21% reported no change and one patient stated that his lifestyle got worse. On a scale ranging from 1 to 5, early postoperative course was painful with a mean score of 2.25; the treatment itself was considered as professional (1.42 +/- 0.8) and well done (1.54 +/- 0.8). Eighty-four percent of the patients reported that they were satisfied with the overall results. All patients would decide again to have photorefractive keratectomy for myopic correction.


Differences between objective and subjective refractions after radial keratotomy.

In patients who are free of pathology, automatic refractions have shown close agreement with the subjective refractions. Clinical experience indicated that the normally strong relationship between objective and subjective refraction is significantly weakened as a result of radial keratotomy. Seventy-two patients were refracted before and after surgery, objectively with a Humphrey Model #510 autorefractor and subjectively using a binocular refraction procedure without cycloplegia. All patients were free of ocular disease and had preoperative myopia ranging from -1.00 to -9.00 diopters as determined by the subjective spherical equivalent. The results indicated that the preoperative difference between the mean spherical automatic and subjective refractions was a clinically acceptable 0.25 diopter. However, postoperatively, there was a statistically significant difference of 1.25 D with the automatic refractor determining more myopic refractions. Subsequent analysis revealed that the age of the patient had a direct bearing on this finding with patients less than 40 years of age showing more minus in the automatic refraction than patients 40 years and older. The postoperative discrepancy between the two refractions may be explained by induced optical aberrations and may contribute towards the visual fluctuations experienced by radial keratotomy patients. It is postulated that the inconsistency in refractive determination is due to optical distortion since the age dependence of this effect may be related to the reduction of pupil size that occurs with aging. In the radial keratotomy patient, the practitioner is faced with a more complex and uncertain refraction that may vary according to refractive procedures used and other factors such as pupil size.


Phototherapeutic keratectomy with excimer laser for Reis-Bückler's corneal dystrophy.

Two patients with decreased visual acuity and recurrent epithelial erosions due to Reis-Bückler's corneal dystrophy underwent phototherapeutic keratectomy with the 193-nanometer excimer laser. Because the epithelial surface was relatively smooth prior to surgery, ablations were performed through an intact epithelium. Postoperatively, visual acuity was improved and symptoms of erosion decreased in both patients. Although no refractive shift was intended with the phototherapeutic procedure, both patients were hyperopic following surgery. Superficial keratectomy with the 193-nanometer excimer laser thus provides an alternative to conventional surgical keratectomy.


Complications of Mersilene sutures in penetrating keratoplasty.

After penetrating keratoplasty, many corneal surgeons adjust sutures to reduce astigmatism and then leave the sutures in place indefinitely. Nylon sutures can hydrolyze and break years after surgery. In a series of human penetrating keratoplasties, we studied the use of polyester (Mersilene) sutures that do not hydrolyze. We performed two prospective studies of polyester (Mersilene) sutures in human penetrating keratoplasty done by one surgeon. Study I was a randomized comparison of combined running and interrupted Mersilene and nylon sutures in 45 consecutive eyes. Study II was a case series of single running Mersilene suture with postoperative adjustment of suture tension to manage astigmatism in 23 consecutive eyes. We evaluated the performance of the suture and the control of astigmatism. The interrupted running suture study demonstrated that interrupted Mersilene sutures were 5.5 times more likely to have handling-related complications than nylon interrupted sutures (p = .01); in addition, they were three times as likely to have tissue-related complications as nylon (p = .16). The running suture study demonstrated an unacceptable complication rate of 69% when Mersilene was used as a single adjustable running suture. At 6 months postoperatively, the median refractive astigmatism for the adjustable cases was 3.37 diopters (mean, 4.03 +/- 2.37 D). Eyes with significant suture-related complications were 2.85 times more likely to have greater than 4.00 D of refractive astigmatism than were eyes without suture-related complications. Mersilene is an undesirable suture for use in penetrating keratoplasty.


Complications of radial keratotomy: eyes with keratoconus and late wound dehiscence.

Radial keratotomy requires a thorough preoperative examination, including photokeratography, to detect early keratoconus. We compared, by light and transmission electron microscopy, the healing process of corneas from two patients after radial keratotomy. Clinically, one patient had a keratoconus and gained no visual benefit from the radial keratotomy. The other patient had a spontaneous corneal perforation at one incision and a hypopyon. Histological studies showed a prolonged healing process in both eyes, with a persistent epithelial plug. Bowman's layer was also interrupted and retracted in both eyes. The inflamed cornea had deep neovascularization. These observations imply that 2 years after surgery, wound healing and, therefore, refraction is not stable. The results show the inappropriateness of radial keratotomy performed on eyes with keratoconus, with the possible risk of delayed corneal perforation.


[ATL and its virus].

A retrovirus called Human T cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T cell leukemia (ATL). A cultured cell line called MT-2, produces constitutively HTLV-1. The characteristics of HTLV-1 produced from MT-2 has been extensively investigated. The molecular mechanism of ATL leukemogenesis by HTLV-1 is discussed.


Patient preference--contact lens or radial keratotomy?

Past clinical experience has suggested that patients are more satisfied after radial keratotomy than when wearing contact lenses. One-hundred patients who had worn contact lenses prior to receiving radial keratotomy compared subjectively these two methods for correcting myopia. The postoperative follow up ranged from 3 months to 13 years. The vast majority (93%) preferred radial keratotomy to the handling of contact lenses. The desire to be independent of optical correction is a sufficient indication for refractive surgery.


[AIDS and its virus].

An etiological agent of AIDS is a human retrovirus called HIV. The genomic structure of HIV features regulatory genes in which tat and rev genes control the viral replication and affect cellular functions. Understanding their molecular mechanism may provide a clue to prevent the onset of AIDS from the viral carriers and to direct drug designing of AIDS.


Clinical strategies for excimer laser therapeutic keratectomy.

Surgical therapy for superficial corneal scars, dystrophies, or surface irregularities with the 193 nm excimer laser shows great promise. Depending upon the character of the pathology to be treated, different surgical strategies are required. Treatment strategies for three patients with diverse corneal pathology are presented. Focal surface irregularities are treated with small laser spot sizes leaving the epithelium intact. Smooth, uniformly distributed subepithelial anterior stromal pathology is best removed with a large spot size through intact epithelium. When scattered scarring of variable thickness is present, selective epithelial debridement permits improved exposure of irregularities in Bowman's layer and the anterior stroma. Guidelines for selective debridement of epithelium and protection of adjacent and underlying stroma with moderate viscosity solutions enhances the surgeons's ability to obtain a smooth and clear surface while minimizing corneal thinning. Even with these strategies and use of plano disc ablation, net hyperopic shift generally occurs with broad large area therapeutic ablation. Superficial corneal opacities and irregularities can be surgically treated with the excimer laser as an alternative to the more invasive procedure of lamellar keratoplasty. Treatment failures can then go on to lamellar keratoplasty while successfully treated patients are more rapidly rehabilitated at lower total cost than a lamellar graft. Refinement of treatment strategies to minimize the hyperopic shift and facilitate masking around irregularities will further improve the results.


[Establishment and characterization of a human colonic cancer cell line expressing carbohydrate antigen 19-9 and carcinoembryonic antigen].

Colonic cancer cell strain KE43 was established from a human colonic cancer diagnosed histologically as a predominantly well differentiated adenocarcinoma with minute foci of poorly differentiated adenocarcinoma. The well differentiated adenocarcinoma cell line was identified as the major morphological picture in xenografts of KE43 and 58 in nude mice, but this changed to poorly differentiated adenocarcinoma in passage 105. Doubling time of this cancer cell line was 22.5 hours in passage 105. The modal numbers of chromosomes were 41 and 76. Cancer cells could be heterotransplanted in 100% of the nude mice. The tumor cells produced and secreted CA19-9, CEA and Laminin into the spent medium. This cell line appears to provide a useful system for studying colonic cancer in vivo and in vitro.


[PCR-SSCP--rapid and easy detection of DNA-sequence changes].

PCR-SSCP analysis is a rapid, simple and sensitive technique for detection of various mutations, including single nucleotide substitutions, insertions and deletions, in PCR-amplified DNA fragments. Here I review, the principle and sensitivity of the technique, and also show how this technique has been used in clinical and basic medical sciences.


Establishment of leukemia cell lines, BALM-6, BALM-7 and BALM-8 with B-cell characteristics from a patient with acute lymphoblastic leukemia.

Three leukemia cell lines, BALM-6, -7 and -8 were established from the bone marrow of a patient with acute lymphoblastic leukemia. Based on immunophenotypic and the cytogenetic analysis and on the expression of immunoglobulins on both the cell surface and in the cytoplasm, BALM-6, BALM-7 and BALM-8 are clonal leukemic cell populations of B cell origin.


Stimulation of orbital growth by the use of expandable implants in the anophthalmic cat orbit.

We evaluated the efficacy of expandable orbital implants to stimulate bone growth in the anophthalmic cat orbit. Eighteen cats unilaterally enucleated at 2 weeks of age received either expandable orbital implants (groups A1 and A2), solid silicone sphere implants of 12 mm or 8 mm (groups B1 and B2), or no implant (group C). Those cats with expandable implants (group A) had the implant size increased by 0.5 ml injections of saline at 2-week intervals starting at 8 weeks of age until a final volume of 4 cc was reached. Four of the expandable implants were found to be only partially inflated at 20 weeks and were subgrouped A2. At 20 weeks of age, the anophthalmic orbits with fully inflated expanders showed no significant difference in either orbital volume or orbital entrance area when compared with control orbits: volume (91.2%), area (95.7%) (p = 0.01). These same orbits also showed a significant increase in both orbital volume and orbital entrance area when compared with the growth obtained by any other group. These other groups showed growth, expressed as a percentage of normal growth, as follows: partially inflated implant: volume (63.0%), area (69.0%); 12-mm sphere implant: volume (57.0%), area (54.5%); 8-mm sphere implant: volume (46.5%), area (44.6%); no implant: volume (47.6%), area (43.6%) (p = 0.01). This study suggests that the use of expandable orbital implants stimulates bony growth in the immature cat orbit. Bony stimulation was proportional to volume implanted, and expandable orbital implants achieved maximum bony stimulation in the groups studied.


Lower eyelid retraction following blepharoplasty.

Thirty consecutive patients with lower eyelid retraction after blepharoplasty were treated surgically with varying degrees of success. Successful outcome depended on various anatomic and pathologic factors, including the time elapsed since blepharoplasty, the prominence of the globe and its effect on eyelid contour, and the degree of septal or skin involvement. Satisfactory results were also dependent on surgical techniques used. We discuss several surgical techniques and offer advice concerning the selection of a surgical procedure in light of various pathologic parameters.


Angle closure glaucoma following a combined blepharoplasty and ectropion repair.

This paper reports an occurrence of angle closure glaucoma following a combined blepharoplasty and ectropion repair. We are unaware of any previous reports of such an incident. Specific to this case was the coexistence of a cataract that contributed to the narrowing of the anterior chamber. This condition, along with pupil dilation secondary to the anesthetic, precipitated a phacomorphic angle closure glaucoma attack, necessitating emergency cataract surgery. Because other procedures involve pupillary dilation as a potential side effect, we recommend an increased awareness of this potential postoperative complication.


Treatment of the paradoxic inversion of the lashes in ectropion.

Ectropion leads to chronic inflammation of the exposed conjunctiva. This inflammation can lead to shrinkage and to a cicatricial paradoxic inversion of the lashes. When the lid margin is surgically brought into its correct position, these lashes may become trichiatic. The surgical eversion of the lid margin at the time of the ectropion operation can prevent this complication.


Eyelid reconstruction with hard palate mucosa grafts.

Hard palate mucosa grafts are an excellent replacement for tarsus and conjunctiva in eyelid reconstruction. Twenty-five eyelids from 18 patients underwent eyelid reconstruction using hard palate mucosa grafts. Patients were treated for a variety of disorders including postblepharoplasty lower eyelid retraction, cicatricial entropion, eyelid retraction secondary to thyroid eye disease, and lagophthalmos following surgery for paralytic ptosis. Surgical results were evaluated, grafts were measured for postoperative shrinkage, and donor site healing was recorded. Several patients had hard palate biopsy specimens evaluated. One of these patients also had a graft biopsied after it had been in place for 3 months. A review of hard palate anatomy and histology and a discussion of surgical technique are presented.


Eyelid reanimation for the treatment of paralytic lagophthalmos: historical perspectives and current applications of the gold weight implant.

Gold weight implants have been used for over 30 years in the setting of eyelid rehabilitation following facial nerve paralysis; however, there has been a renewed interest by ophthalmologists in this reanimation technique in recent years. This article reviews the history of gold weight eyelid implantation and presents the results of gold weight eyelid implantation over a 15-month period in 23 patients. A 92% success rate was obtained (average follow-up, 12 months). Surgical technique and indications are discussed along with postoperative complications.


Lacrimal mechanics in the enucleated state.

Our understanding of tear-flow mechanics is based upon work performed on eyes in the normal, nucleated state. On this basis, decisions are made regarding the reconstruction of lacerated canaliculi. When called upon to repair such a laceration in a patient who is coincidentally undergoing a traumatic enucleation, the surgeon has traditionally done so when it was practical. This assumes that the tear-flow requirements in these patients are similar to those of patients in the nucleated condition. We have investigated twelve patients after traumatic enucleation and believe, based on this preliminary work, that eyes in the enucleated state may not have the same tear-flow requirements and therefore may not require canalicular reconstruction.


Postcataract surgery endophthalmitis in a patient with a functioning Jones tube.

Dacryocystorhinostomy with Jones tube placement has proven to be an effective method for correcting upper-system lacrimal drainage obstruction. The present case report illustrates the potential risk of bacterial contamination of the operative field during subsequent cataract surgery by retrograde passage of airway secretions. Temporary occlusion of the Jones tube by a silicone plug can eliminate this potential source of endophthalmitis. In addition, temporary occlusion of the Jones tube in the office can be used to determine the effectiveness of lacrimal drainage through a reconstructed canalicular system.


Eyebrow analysis after blepharoplasty in patients with brow ptosis.

Fifteen patients and 28 eyes with measurable eyebrow ptosis underwent standard upper eyelid blepharoplasty with or without sub-brow fat excision. The patients were educated about the status of their eyebrow position and the effects of either direct or indirect methods of brow elevation. The patients either refused or chose not to undergo browpexy by any method. Eleven patients and 22 eyes showed an insignificant change in their eyebrow position after surgery. Two patients and three eyes had a mild to moderate descent of the eyebrow and two patients had what was felt to be significant worsening of their eyebrow ptosis in one or both eyes. However, all were pleased with their result. Information as such, after a careful review of the literature, has not previously been published.


Atypical magnetic resonance findings in an orbitofrontal cholesterol granuloma.

Cholesterol granuloma of the orbit is an uncommon entity, although it frequently occurs in the middle ear and petrous apex. It is isodense with brain on computed tomographic scanning and cannot always be differentiated from more serious conditions. Magnetic resonance imaging (MRI) has facilitated the preoperative diagnosis of cholesterol granuloma outside of the orbit because of high signal characteristics on T1- and T2-weighted images. These findings have been considered nearly pathognomonic, but they have previously been described in only one patient with orbitofrontal involvement. We present a case of orbitofrontal cholesterol granuloma with uncharacteristic signal intensities on magnetic resonance imaging.


The CT and MRI features of an unusual case of isolated orbital neurofibroma.

A 35-year-old woman developed painful proptosis of the left eye over a period of 3 weeks. Orbital computed tomography and magnetic resonance imaging revealed a well-circumscribed superior orbital tumor with variable density. The mass was removed entirely by way of a superior orbitotomy. Histopathologically, it was found to be a neurofibroma. The patient had no clinical findings of neurofibromatosis. The presence of extensive myxomatous degeneration and the dense collection of collagen bundles in the tumor are correlated with the unusual computed tomography and magnetic resonance imaging features.


Homing of blood, splenic, and lung emigrant lymphoblasts: comparison with the behaviour of lymphocytes from these sources.

The distinctive homing patterns of [125I]deoxyuridine-labelled lymphoblasts and 51Cr-labelled lymphocytes from the three sites--splenic and pulmonary venous emigrants, and peripheral blood--were demonstrated by study of their entry into a large number of tissues. These included the major organs such as the lung, liver, bone marrow, spleen, skin, and muscle, and several lymph nodes (LNs), Peyer's patches (PPs), tonsils and thymus, portions throughout the gastrointestinal tract and immunologically-stimulated sites. Major differences in homing of blood blasts (up to 4-fold) were found in particular tissue types, such as the different LNs, three PP types, and the three tonsils, and their distribution was quite different from lymphocytes. While splenic blasts behaved like blood blasts, lung blasts showed even more distinctive homing, e.g. to tissues with particular blast uptake, including spleen, stomach, bladder, portal and stimulated LNs, and liver and lung. While blast recovery data showed that all types homed well to bone marrow (about 25%) and the gastrointestinal wall (about 15%), the roughly 50% found in blood, muscle, skin, lung, and liver showed some homing preferences: blood blasts tended to stay more in blood, splenic blasts to home to muscle, and lung blasts to liver and lung. These studies have demonstrated that physiologically-derived lymphoblasts are not predominantly mucosal-homing but distribute through several non-lymphoid organs and that, even considering only those in the blood compartments, they show differences in homing preference.


Five novel antigens illustrate shared phenotype between mouse thymic stromal cells, thymocytes, and peripheral lymphocytes.

Previously we characterized by immunohistology a group of rat anti-mouse thymic stromal mAbs (MTS 12, 32, 33, 35, and 37), which recognized novel plasma membrane determinants on both thymic stromal cells (TSCs) and thymocytes. The present study investigates in more detail this incidence of shared phenotype by an extensive flow cytometric analysis of MTS mAb reactivity on TSCs, thymocyte subsets, peripheral lymphocytes, and bone marrow cells. Examination of freshly isolated or cultured heterogeneous TSCs and TSC clones confirmed that the mAb identified plasma membrane molecules on distinct subsets of these cells. All but MTS 12 reacted with epithelial cells. Triple-labelling illustrated that MTS 32, 33, and 37 were also reactive with more than 90% of total thymocytes, but varied in their distribution on the four major CD4 and CD8 defined subsets. MTS 12, staining with thymic vascular endothelium by immunohistology, labelled more than 95% of each subset. MTS 35 reactivity in each subset correlated strongly with only the immature populations. Examination of peripheral lymphocytes by triple- and double-labelling unexpectedly showed that MTS 33, 35, and 37 did not recognize peripheral T cells but labelled all B cells. MTS 32 was negative for B cells, but positive for all CD8+ T cells, yet only a subset of CD4+ T cells. Further, MTS 33, 35, and 37 were present on a significant percentage of bone marrow cells. MTS 12 reacted with virtually all peripheral T and B cells, and about 50% bone marrow leukocytes. Collectively these results reveal the same novel epitopes on different thymic cell types and subsets thereof, highlighting specific similarities between cells of apparently diverse lineages. These findings may be of importance in the delineation of intercellular communications within the thymus and emphasize the integrated nature of the microenvironment in this organ.


Characterization of murine CD10, an endopeptidase expressed on bone marrow adherent cells.

The CD10/neutral endopeptidase (NEP) gene was identified in murine genomic DNA using a human CD10 cDNA probe. It is transcribed most abundantly in kidneys resulting in RNA transcripts of 3.4, 6.0, and 6.2 kb. The activity of the murine CD10/NEP shows identical kinetic parameters, Km and Ki, to those observed for this enzyme in other species. Two mAbs raised against rabbit NEP detect a 100 kDa protein by Western blot analysis; the antigen immunoprecipitated from extracts of lung shows specific NEP activity. CD10/NEP, as analyzed by Western blot and enzymatic activity, is expressed at high levels in kidney and lung, and at lower levels in liver, brain, thymus, spleen, and bone marrow. Analysis of bone marrow subpopulations indicate that the majority of CD10/NEP is associated with cells adherent to plastic and with subpopulations that do not express the surface markers AA4.1, B220, Mac-1, and Gr-1. These results suggest that CD10 is primarily associated with the stromal elements in murine bone marrow. A bone marrow stromal line, BMS 2.2, also expresses high levels of CD10/NEP. This peptidase activity on the surface of stromal cells may influence lymphopoiesis or other hematopoietic processes through the hydrolysis of regulatory peptides in the microenvironment.


MHC and malaria: the relationship between HLA class II alleles and immune responses to Plasmodium falciparum.

In mice, immune responses to subunits of defined malaria antigens are regulated by genes mapping within the MHC and it has been suggested that such genetic restriction will be a major obstacle in the development of a human malaria vaccine. The relationship between class II human leukocyte antigen (HLA) genes and immune recognition of three candidate antigens for a vaccine against Plasmodium falciparum malaria has been investigated in a human population living in a malaria endemic area of West Africa. The study population was shown to be extremely heterogeneous for HLA class II alleles and marked differences in allelic frequency were detected between members of different ethnic groups. One class II DQA-DQB combination (serological specificity DQw2) was particularly common among members of the Fula ethnic group. This haplotype was significantly associated with higher than average levels of antibody to a peptide epitope, (EENV)6, of the malaria antigen Pf155/RESA. There was little evidence of association between HLA class II genotype and cellular proliferative or interferon gamma responses to the antigens tested. Overall, the number of significant associations between immune responses and specific HLA class II haplotypes was greater than would be expected by chance but less than would be expected if class II-dependent genetic restriction were a major factor governing human immune responses to malaria antigens. Thus, although some qualitative variation in the immune response to vaccine antigens may occur in ethnically different target populations, widespread HLA-associated nonresponsiveness to a multivalent subunit malaria vaccine is unlikely.


Thymocytes can tolerize thymocytes by clonal deletion in vitro.

Clonal deletion of thymocytes bearing TCR for self antigens is one major mechanism of T cell tolerance induction. Peptide antigen-induced deletion of thymocytes from alpha beta TCR transgenic mice has been studied using single cell suspension cultures. The results show that antigen-presenting immature CD4+CD8+ thymocytes can tolerize antigen-reactive immature thymocytes in vitro by programmed cell death (apoptosis) 6-8 h after antigen exposure. Antigen-induced apoptosis of immature thymocytes was inhibited by antibodies specific for the alpha beta TCR, CD3, CD8, and LFA-1 molecules. This implies that clonal elimination of self-reactive CD4+CD8+ thymocytes does not depend on specialized deleting cell types in the thymus and occurs whenever the TCR of immature thymocytes bind antigen fragments presented by MHC molecules.


Effects of the lpr/lpr mutation on T and B cell populations in the lamina propria of the small intestine, a mucosal effector site.

MRL mice, which develop a lymphoproliferative disease characterized by increased numbers of alpha/beta T cell receptor+ (TCR+) B220/6B2+CD4-CD8- T cells [lymphoproliferation (lpr) T cells], were studied for the effect of the lpr/lpr mutation on the mucosal immune system in the gastrointestinal (GI) tract. We analyzed the effect of the lpr gene mutation on T and B cell populations in the Peyer's patches (PP) and the lamina propria lymphocytes (LPLs), as examples of major IgA inductive and effector tissues in the GI tract respectively. Normal mouse PP contain B cells committed to IgA (surface IgA+) but only low numbers of B cells producing IgA. However, enhanced spontaneous IgA and IgG synthesis occurs in the PP of MRL mice. Further, we have now shown that PP of MRL mice are populated by lpr T cells. Interestingly, lpr T cells were not present in significant numbers in LPLs of MRL mice, even in older animals. Of interest was the finding that the ratio of CD4+ to CD8+ T cells in the lamina propria was lower in MRL when compared with control mice, and the CD8+ T cell subset actually predominates in LPLs of autoimmune mice. In addition, the number of gamma/delta TCR+ T cells in LPL of MRL lpr/lpr mice was significantly increased, especially in MRL lpr/lpr mice at 6 and 12 weeks of age. When the isotype distribution of B cells in LPLs was analyzed, no changes were noted in MRL lpr/lpr mice in comparison with MRL +/+ or normal control mice, and the pattern was IgA much greater than IgM greater than IgG. These results show that although increased numbers of CD8+ T cells and gamma/delta TCR+ cells occur in the LPLs of MRL mice, a normal distribution of plasma cell isotypes (IgA much greater than IgM greater than IgG) is found in this mucosal compartment. Further, Ipr T cells do not develop in the lamina propria compartment of the GI tract.


A self-reactive T cell population that is not subject to negative selection.

In male mice expressing a transgenic alpha beta TCR which recognizes a male antigen (HY), T cells which do not express normal levels of CD8 escape thymic deletion and appear in the periphery. These consist of two distinct populations, one which lacks expression of both CD4 and CD8, and one with low levels of CD8. Neither population has anti-HY reactivity, consistent with the known requirement of this TCR for CD8. We now describe the consequences of expression of both the anti-HY TCR transgene and a constitutive CD8.1 transgene on T cells of male mice. Peripheral T cells in these male 'double transgenic' mice express both the anti-HY TCR and normal levels of CD8, and can proliferate to male antigen in vitro. These cells do not express the endogenous allele of CD8 (CD8.2), suggesting that the increase in CD8 levels due to the CD8.1 transgene leads to the deletion of the CD8.2low population. In contrast, the CD8.1 transgene does not lead to the deletion of the CD8.2- population. This implies that, unlike the majority of alpha beta T cells, TCR+CD4-CD8- cells in TCR transgenic mice are not subject to deletion.


Transforming growth factor-beta 1 enhances IgG and IgA sheep red blood cell responses.

Antibody responses to ingested antigens can be inhibited by a mechanism known as oral tolerance which acts to prevent excessive stimulation from luminal contents. Local IgA responses can be induced in this non-responsive environment and during intestinal inflammation, mucosal IgG responses can also be increased. The purpose of this study was to compare a panel of cytokines to factors from macrophage-T cell co-culture supernatants for their ability to enhance isotype and sheep red blood cell (SRBC)-specific plaque-forming cell responses in an in vitro model of oral tolerance. IL-2, IL-4, IL-5, and IL-6, which have been implicated in IgA regulation of lipopolysaccharide-stimulated B cells, were not capable of enhancing responses in tolerized cultures; however, transforming growth factor (TGF)-beta 1 had a dose-dependent ability to enhance responses to the T cell-dependent antigen SRBCs in this system. The enhancement was only seen when antigen was present and was neutralized by specific rabbit antiserum but not normal rabbit IgG. Similar treatment of soluble factors from the macrophage-T cell co-cultures did not inhibit their ability to enhance responses suggesting at least two distinct molecular mechanisms could augment responses in tolerized cultures. This was substantiated further by showing that TGF-beta 1 was not isotype-specific. In contrast, adsorption of the macrophage-T cell co-culture supernatants against monoclonal IgA or IgG removed isotype-specific binding factors which were necessary for the enhancement of IgA and IgG respectively.(ABSTRACT TRUNCATED AT 250 WORDS)


'Natural' T cells responsive to malaria: evidence implicating immunological cross-reactivity in the maintenance of TCR alpha beta+ malaria-specific responses from non-exposed donors.

It is now generally accepted that peripheral blood of humans not exposed previously to malaria contains T cells which proliferate vigorously in response to malaria parasites and antigens. Although it has been claimed that these cells express a memory phenotype, their origin is uncertain. We have examined the phenotype and immunological responses of such cells. We confirm that these cells do express the 'memory phenotype', CD45Ro, in that depletion of such cells, but not of CD45Ra (virgin) cells, abrogates the immune response to malaria parasites. In an effort to define the genesis of these responses, numerous malaria-specific T cell clones have been generated from non-exposed individuals. These were tested for reactivity to a large panel of common bacterial, viral, and fungal pathogenic and non-pathogenic organisms. Most clones proliferated vigorously in response to one or more such organisms, while many clones demonstrated smaller but significant degrees of proliferation in response to many different organisms. Our data offers insights into the maintenance of immunological memory. All clones examined were CD3+, CD4+, CD8-, TCR alpha beta+, and TCR delta-. The ratio of TCR alpha beta+ to TCR delta+ cells among peripheral blood lymphocytes increased during polyclonal culture in the presence of parasite. The high frequency of such cells in peripheral blood (1/800-1/9000), and their response to a wide range of geographically different Plasmodium falciparum isolates and clones by both proliferation and lymphokine secretion (predominantly IFN-gamma) with a high degree of sensitivity (less than 1 parasite/microliters blood in some cases) suggests that these cells must be quickly activated following malaria infection. Their contribution to the outcome of the disease (protection/immunopathology) may be significant.


Extensive CD4 cross-linking inhibits T cell activation by anti-receptor antibody but not by antigen.

Anti-CD4 mAbs have been shown to inhibit T cell activation in a variety of ways. We have tested a panel of IgG and IgM anti-CD4 mAbs for their effects on the activation of a cloned T cell line by antigen presented by syngeneic accessory cells, by soluble anti-T cell receptor antibodies, and by mitogenic lectins. Both IgM and IgG mAbs to CD4 inhibit responses to mitogenic lectins. However, IgM, but not IgG, anti-CD4 antibodies inhibit T cell activation by mAbs specific for the TCR. This inhibitory activity appears to be due to the signaling effects of IgM mAbs, as cross-linked IgG antibodies mimic the behavior of the IgM anti-CD4 antibodies. Inhibition of T cell activation correlates with the ability of IgM and of cross-linked IgG anti-CD4 antibodies to induce tyrosine phosphorylation of the CD4-associated tyrosine kinase p56lck and an unknown substrate, pp32. Surprisingly, we find that the IgM anti-CD4 mAbs tested had no effect on the specific antigen recognition, despite their potent inhibitory effects on the other responses of the same cloned T cell line. These results suggest that multivalent CD4 interactions with ligands such as MHC class II molecules are inhibitory of T cell activation, but that this inhibition can be reversed when CD4 and the TCR bind the same ligand. We discuss the possible implications for positive intrathymic selection of these findings on signaling through CD4.


Substituent distribution on O,N-carboxymethylchitosans by 1H and 13C n.m.r.

The use of the n.m.r. method in the investigation of chitosan carboxymethylation was evaluated. It seems to be the most effective technique to determine concurrently the degree and the position of substitution of the carboxymethylated chitosan derivatives. The 13C-n.m.r., by the DEPT method, 1H-1H and 1H-13C-n.m.r. correlations give much valuable information from the chemical shifts of the complex carboxymethylchitosan spectra. The relative reactivity of the functional groups of chitosan towards carboxymethylation was also determined assuming a higher reactivity of the C-6 position.


Effect of chemical modifications on the susceptibility of collagen to proteolysis. II. Dehydrothermal crosslinking.

Collagen was dehydrothermally treated (heat cured) by heating dry under vacuum at 60, 80, 100 and 120 degrees C. The change in stability was determined by subjecting to measurement of gross crosslinking, content of lysino-alanine and naturally occurring collagen crosslinks, shrinkage temperature (TM), susceptibility to digestion by lysosomal thiol proteases, and susceptibility to pepsin and trypsin. Morphological changes were examined by electron microscopy. The in vivo biodegradation of dehydrothermally treated collagen sponges was investigated using a rat lumbar muscle implantation model for up to 28 days. For all heat-cured collagens, the data strongly indicated that both crosslinking and denaturation/degradation was present in increasing quantities with increasing temperature of treatment, its level was too low (maximum 179 pmol mg-1) to account for the decreased solubility and increased molecular weight gross changes observed. Increasing resistance of treated collagen to both lysosomal cathepsins and pepsin correlated well with increased crosslinking and increasing temperature of the heat-curing process. However, increased denaturation/degradation of the collagen at higher temperatures was revealed by electrophoretic analysis, trypsin hydrolysis data and by electron microscopy. Differential scanning calorimetry (d.s.c.) correlated well with these results showing an increased level of denaturation in heated samples. The in vivo study showed little difference between control and heat-cured samples except for the material treated at 120 degrees C which was biodegraded in vivo at a significantly faster rate. The data shows, therefore, that crosslinking induced by the dehydrothermal treatment of collagen decreases its rate of proteolysis at acid pH in vitro. However, the simultaneous denaturation/degradation of the protein during the heat-cure process appears to be a more important factor in determining the fate of the material implanted into rat muscle.


Patterson methods in fibre diffraction analysis.

The potential of the Patterson methods for X-ray diffraction studies of textures is examined in DNA fibres. Patterson analysis, which is rarely used in these situations, is shown to yield important information on the preliminary interpretation of diffraction patterns and to increase the reliability of the three-dimensional structural pattern obtained for polymeric molecules. We also show how the screw symmetry of helical molecules can be used to calculate their electron density by means of the three-dimensional Patterson function.


Comparative structural analysis of desmoplakin, bullous pemphigoid antigen and plectin: members of a new gene family involved in organization of intermediate filaments.

Desmoplakins (DP) and bullous pemphigoid antigen (BPA) are major plaque components of the desmosome and hemidesmosome, respectively. These cell adhesion structures are both associated intimately with the intermediate filament (IF) network. Structural analyses of DP and BPA sequences have indicated that these molecules are likely to form extended dumbbell-shaped dimers with a central rod and globular end domains. Recent sequence data have indicated that the N-terminal domains of both DP and BPA (like their C-terminal domains) are highly related: the former contain regions of heptad repeats that are predicted to form several alpha-helical bundles. Comparisons of DP and BPA protein sequences with that of plectin (PL), a 466 kDa IF-associated protein, have also revealed large scale homology. Identities between their N-terminal domains are: DP:BPA = 35%, DP:PL = 32%, BPA:PL = 40%, suggesting that BPA is more closely related to PL than DP in this region. In the C-terminal domains, which contain a 38-residue repeating motif, however, DP and PL are closer relatives (identities: DP:BPA = 38%, BPA:PL = 40%, DP:PL = 49%). The central domains of all three proteins have extensive heptad repeat substructure, express the same periodic distribution of charged residues, and are predicted to form two-stranded alpha-helical coiled-coil ropes. These observations suggest that DP, BPA and PL belong to a new gene family encoding proteins involved in IF organization.


Molecular mechanical study of the stability of the Lys-Ala-Ala tripeptide dimer.

A molecular mechanical study of two Lys-Ala-Ala tripeptide chains in interaction is presented. The study was carried out to explore the feasibility of dimer formation and explain some features of the crystal structure not completely understood. The role of the counterions present in the crystal structure on the conformation has been included in this study by investigating the effect of removing the charges on the lysyl side chains. The results of the present molecular mechanical study explains well the structural features found by X-ray crystallography, complementing that study.


B-Z conformational transition and hydration of poly (dC-dG).poly (dC-dG) in fibres.

The B-Z transition of poly(dC-dG).poly(dC-dG) has been studied by fibre X-ray diffraction and measurement of fibre dimensions. The polymorphism of the Z form is well observed as a function of variations of the r.h. (relative humidity). The Z to B transition is obtained at very high r.h. values. The cooperative transition from B to Z is associated with a disorganization of the fibre. Details about the hydration of the polynucleotide during conformational transitions are presented and it is shown that a nucleotide in Z form can be associated with up to 16 water molecules and up to 22 when in the B form.


Improved method for i.r. determination of the degree of N-acetylation of chitosan.

Three published i.r. absorption band ratios for determining the % N-acetylation of chitosan have been used to follow the rate of alkaline deacetylation of chitin. Only one, the A1655/A3450 ratio, gives the expected rate of deacetylation curve. Consideration of the various i.r. ratios has led to a new relationship, % N-acetylation = (A1655/A3450) x 115, where the absorbance of the amide I band at approximately 1655 cm-1 is determined using the baseline proposed previously. The values obtained using this proposed relationship agree closely with those obtained from dye adsorption measurements for chitosans having % N-acetylation values in the range 0-55%.


Helicoidal self-ordering of cellulose microfibrils in aqueous suspension.

In many skeletal support systems of plants and animals, cellulose, chitin, and collagen occur in the form of microfibrils ordered in a chiral nematic fashion (helicoids). However, these structures remain poorly understood due to the many constituents present in biological tissues. Here we report an in vitro system that attracts by its simplicity. Only one chemical component, cellulose, is present in the form of fibrillar fragments dispersed in water. Above a critical concentration the colloidal dispersion separates spontaneously into a chiral nematic liquid crystalline phase. On drying this phase solidifies into regularly twisted fibrillar layers that mimic the structural organization of helicoids in nature.


Quantifying anti-inflammatory agents' potency by measurement of response to dinitrochlorobenzene challenge.

Classical assays of topical corticosteroid potency based on the induction of vasoconstriction are unsatisfactory for a number of reasons. These include the doubtful relevance of vasoconstriction to immune inflammation, and more importantly, the inability to compare non-steroidal agents with corticosteroids. Here we describe a simple assay in which the inhibitory effect of agents upon delayed type hypersensitivity response to dinitrochlorobenzene can be quantified by measurements of reaction as skinfold thickness with Harpenden callipers. Using this system we have confirmed the greater potency of clobetasol propionate (Dermovate) compared with betamethasone valerate (Betnovate), but the evidence for an inhibitory effect of topical cyclosporin (10% cream) compared with base on this response is less convincing.


Determination of the action spectrum for UV-induced plasminogen activator synthesis in mouse keratinocytes in vitro.

Mouse epidermal keratinocyte-derived Pam 212 cells were irradiated with UV light, and the culture media were examined for plasminogen activator (PA) activity by measuring the capacity to convert exogenous plasminogen into plasmin. Exposure of cells to a broad spectrum of light in the UVB range induced a significant elevation of PA activity at 16 h after irradiation. A dose-response study revealed that a maximal enhancement, 15-fold higher than non-irradiated controls, was induced at a sublethal UVB dose of 100 J/m2, which significantly inhibited cell proliferation without affecting cell viability. Addition of 5 micrograms/ml of cycloheximide lowered the UV-induced elevation of PA activity, suggesting that protein synthesis is required for this phenomenon. Action spectra for PA synthesis were obtained by irradiating cells with monochromatic light ranging from 250 to 360 mm, and the data demonstrated that the action spectrum was 250-320 nm in length with a peak between 260 and 280 nm. The results suggest that UV exposure is an important physiological trigger for modulating PA synthesis in the epidermis.


Anti-proliferative effects of protein kinase C inhibitors in human keratinocytes.

Various lines of evidence indicate that protein kinase C, a key enzyme in transmembraneous signal transduction, is involved in the regulation of keratinocyte proliferation. In the present study we have investigated the effects of various structurally unrelated protein kinase C inhibitors on the proliferation of HaCa T cells, a non-tumorigenic human keratinocyte cell line. All protein kinase C inhibitors dose-dependently inhibited cell proliferation as assessed by the incorporation of radioactively labelled thymidine and amino acids as well as the increase in total protein content in keratinocytes. The potencies of the drugs to inhibit cell proliferation were strongly correlated to their inhibitory potency on purified protein kinase C, displaying a correlation coefficient of 0.97. Methotrexate, an anti-proliferative drug, was found not to inhibit protein kinase C. Therefore, our data provide evidence that protein kinase C is crucially involved in the regulation of keratinocyte proliferation but is not the only target of anti-proliferative drug action.


Production and characterization of monoclonal antibodies to Treponema pallidum.

This study was attempted to produce the monoclonal antibodies specific for Treponema pallidum and to investigate their characteristics, thereby contributing to identify the antigenic structure and to apply the diagnosis of syphilis. The seven clones (YS 3, YS 75, YS 307, YS 481, YS 343, YS 1 and YS 406) secreting monoclonal antibodies reactive with T. pallidum were produced. The isotypes of the seven monoclonal antibodies produced were defined. Optical densities of the 7 monoclonal antibodies were ranged from 0.59 to 1.48 as measured by ELISA. Monoclonal antibodies from 5 of the 7 clones which could agglutinate sheep RBC sensitized with T. pallidum, showed strong fluorescences. The monoclonal antibody from YS 343 was cross-reactive with non-pathogenic treponemes, but the other 6 monoclonal antibodies reacted with T. pallidum specifically. On immunoblotting, monoclonal antibodies from 5 of the 7 clones reacted with a polypeptide of a molecular weight of 47 kDa, and monoclonal antibodies from YS 343 reacted with a polypeptide of 64 kDa common to both T. pallidum and T. phagedenis. The above results revealed that 7 clones secreting monoclonal antibodies reactive to T. pallidum were produced successfully, and specific antibodies reacting with major antigenic polypeptides of a molecular weight of 47 kDa would be useful in the diagnosis of syphilis in the future.


Cholinergic sensitivity of the eccrine sweat gland in trained and untrained men.

The purpose of this study was to compare the cholinergic responsiveness of the human sweat gland in trained and untrained men. Eighteen healthy male volunteers (9 trained, 9 sedentary) served as subjects. Pilocarpine concentration vs. sweat rate dose-response curves were obtained from each subject using iontophoresis. From these measurements, maximal iontophoretic sweat rate (SRmax) was determined and correlated with each subject's maximal oxygen uptake (VO2max). The trained group had a significantly (P less than 0.05) greater mean SR max and their mean dose-response curve was shifted up and to the left, as compared to the sedentary controls. Furthermore, VO2max was significantly correlated with SRmax (r = 0.76). These findings suggest that the modification occurring in the human sweat gland after training may include improvements in both SRmax and cholinergic sensitivity, and support the hypothesis that the potentiation in sweating following training is achieved via a peripheral mechanism.


Production of experimental staphylococcal impetigo in mice.

We produced a staphylococcal impetigo model by epicutaneous inoculation in mature mice. A strain isolated from a human impetigo was used. Five-week-old female mice (ddy-strain) were used with and without pre-treatment by cyclophosphamide (Cy) (2 mg/mouse) for 5 days. The back skin of mice was shaved by a razor blade and slightly abraded by sand paper. Bacterial suspension (1.4 x 10(7) CFU/0.05 ml) was applied on the abraded areas which were then occluded under sterile plastic plaster. Although intraepidermal blisters developed in non-Cy-treated mice, massive neutrophil infiltration obscured the changes there. Development of subcorneal bullae in Cy-treated mice inoculated with Staphylococcus aureus was first observed at 3h and enlargement of bullae was apparent at 12 h after inoculation. The bullae produced in Cy-treated mice contained numerous S. aureus bacilli. Electronmicroscopically, S. aureus cells invaded the horny layer at 1/4 h. A clear halo was seen between S. aureus cells and horny cells. S. aureus cells attached to surrounding horny cells by fibril-like structures. The halo-like spaces became larger, coalesced and then developed into an intraepidermal blister. Our new method to produce human impetigo-like blister in Cy-treated adult mice may contribute to disclosing the mechanisms of blister formation in epidermis by S. aureus. Due to the thin structure of mouse epidermis, only specimens taken earlier than 24 h after inoculation were considered appropriate.


O6-alkylguanine-DNA alkyltransferase activity in human malignant melanoma.

O6-alkylguanine has been known to be the major lesion in DNA for the cytotoxicity of alkylating agents and it is repaired by O6-Alkylguanine-DNA alkyltransferase (O6-AGT). To examine the relation of O6-AGT to the clinical characteristics in malignant melanoma (MM), O6-AGT activity in 13 human MM tissues was measured. The activity in tumor tissues varied widely from 0 to 0.11 pmol/mg protein. The activity in normal skin tissues was lower and less variable than in the tumors. The activity was not related to the tumor size or clinical stage of melanomas, but it was higher in tumors after chemotherapy with alkylating agents than in those without chemotherapy. In metastatic tissues, in primary tumors of the patients with metastases and in tumors of the patients with bad prognosis, the activity was also high. Two of the tumors, having the highest O6-AGT activity, were both transplantable to nude mice. These results suggest two possibilities; melanomas exposed to the alkylating agents may change to have high O6-AGT activity, followed by the resistance to such agents, or O6-AGT in melanomas may be originally diverse. O6-AGT activity in the tumour tissue may represent the effect of alkylating agents and can be used in selecting the methods of therapy.


Survival time after AIDS in pregnancy.

To examine the suggestion, based on theoretical considerations and case reports, that pregnancy decreases survival time after AIDS (acquired immunodeficiency syndrome). A total population study in Edinburgh. A city with a moderately high prevalence of human immunodeficiency virus (HIV) infection in women. AIDS has been diagnosed in 22 women, five of whom had a pregnancy. Clinical characteristics, disease presentation, lymphocyte markers, pregnancy outcome, subsequent progress and survival time. Pregnancy was not obviously associated with a difference in clinical findings. The mean survival time for the three women with a pregnancy who died was 24 months and for the 11 women without a pregnancy it was 15 months. (P = 0.63 log rank test). The clinical presentation, severity of the illness and laboratory findings were not obviously different in pregnancy. All three women who had Pneumocystis carinii pneumonia for the first time in pregnancy survived this initial episode. Survival time was not obviously reduced by the conjunction of pregnancy with AIDS.


Experience with the Cardial inferior vena cava filter as prophylaxis against pulmonary embolism in pregnant women with extensive deep venous thrombosis.

To report the use of the Cardial inferior vena caval filter as prophylaxis against pulmonary embolism in pregnant women with extensive iliofemoral thrombosis. Leicester Royal Infirmary. Four pregnant women with extensive iliofemoral thrombosis, deemed to be at high risk of pulmonary embolism, managed over a period of one year. In addition to standard full anticoagulation with heparin, the Cardial inferior vena cava filter was introduced percutaneously under local anaesthesia through the unaffected contralateral femoral vein and positioned in the inferior cava below the renal veins. The procedure was uncomplicated and did not compromise feto-maternal condition. There was no evidence of pulmonary embolism after filter insertion. The use of inferior vena cava filters should be considered as an adjunct to intravenous anticoagulation in pregnant women with extensive deep vein thrombosis of the lower limbs.


The effect of magnesium sulphate on blood flow velocity in the maternal retina in mild pre-eclampsia: a preliminary colour flow Doppler study.

To investigate the use of colour flow Doppler ultrasound to identify retinal blood vessels in women with mild pre-eclampsia and to assess the effects of an infusion of magnesium sulphate on the baseline retinal blood flow-velocity. Prospective descriptive study. Ben Taub Hospital, Baylor College of Medicine, Houston, Texas, USA. Eight women with mild pre-eclampsia. Baseline colour flow Doppler ultrasound assessment of the central retinal artery (CRA) and posterior ciliary artery (PCA) blood flow-velocity before intravenous infusion of 6 g of magnesium sulphate in 100 ml of 5% dextrose water over 20 min, followed by repeat Doppler measurement. Blood pressure, heart rate, pulsatility index (PI), resistance index (RI), angle-corrected flow-velocity (cm/s). The CRA and PCA were easily and reliably identified. The infusion of 6 g of magnesium sulphate significantly reduced (P < 0.05) the mean CRA PI from 1.42 (SD 0.67) to 0.93 (SD 0.18) and the mean CRA RI (P < 0.008) from 0.62 (SD 0.07) to 0.53 (SD 0.10). The PCA PI decreased (P = 0.01) from 0.97 SD (0.14) to 0.78 SD (0.18) and the PCA RI decreased (P = 0.02) from 0.58 SD (0.07) to 0.48 SD (0.09). Angle-corrected flow-velocity decreased non-significantly after the magnesium sulphate infusion. Patients with pre-eclampsia have high CRA and PCA flow-velocity suggestive of vasospasm. Magnesium sulphate acutely vasodilates the small arteries in the retina, increasing retinal blood flow. Changes in the blood flow in the retina may be indicative of similar changes in other end-arterial branches of the internal carotid artery. This non-invasive Doppler method may provide a means to monitor the effects of therapeutic interventions in patients with pre-eclampsia.


Placental bed biopsies in placental abruption.

To investigate structural changes in the uteroplacental blood vessels in association with placental abruption. Prospective descriptive study. 18 women with clinical evidence of severe placental abruption delivered by caesarean section. Placental bed biopsies were obtained at caesarean section and studied histologically. Six specimens did not include trophoblast in the myometrium and were therefore not representative of the placental bed. Of the 12 representative specimens, seven demonstrated absence of physiological transformation of the utero-placental arteries (four of these were from hypertensive patients). Four biopsies showed abnormal vascular structures deep in the myometrium. One of these abnormal vessels included a fresh plug and extensive surrounding intramyometrial haemorrhage. Vascular malformations in association with placental abruption may be the result of trophoblastic invasion and could be the site of vessel rupture. Further descriptive and comparative studies are needed.


The modified Pereyra procedure: a clinical and urodynamic review.

To review the clinical and urodynamic outcome of treatment by the modified Pereyra procedure in 93 women with genuine stress incontinence. Retrospective review. Harbor/UCLA Medical Center and Los Angeles County Women's Hospital, Los Angeles, California, USA. Clinical and urodynamic assessment one year after modified Pereyra procedure. Overall 82% of patients were subjectively cured while only 63% were objectively cured. Women with failed surgery had significantly lower pre-operative maximum urethral closure pressures. The procedure had a low operative and postoperative morbidity with no significant disturbance of voiding function noted at one year follow-up. Our results with the modified Pereyra procedure for stress incontinence showed a significantly lower success rate than has been reported from many previous studies.


Ethics education at the engineering/medicine interface.

There is a functioning interface between engineering and medicine. There are also wide-spread indications in the scientific community that there is increased concern for ethical matters in science and that the time has arrived for more instruction in this area. One reason for this in bioengineering is the rapidly growing complexity of technology in both engineering and medical biology. The ensuing difficulty in communication cannot be remedied just with more technical information. Instead bioengineers need an improved understanding of medical education and practice, and medical ethics is fundamental to this. Ethical considerations are crucial to decision making and therefore to all areas of professional endeavor in bioengineering. As a framework for ethics education, bioengineers need to gain a better understanding both of medical education in general and of medical practice, particularly the case study method in education and the nature of decision making in medical practice. Key subject areas in medical ethics for bioengineers include rights and duties of physicians, determination of death, team ethics, patient privacy and informed consent, research ethics, and malpractice. An ethics curriculum for bioengineers should be taught using both informal but regular exposure to clinical activities and clinicians, and formal classroom work. In the medical ethics classroom setting, writing assignments are essential to provoke each student to the introspection and commitment needed to form a personal professional ethos.


A simplified method of laparoscopic presacral neurectomy for the treatment of central pelvic pain due to endometriosis.

To describe optimal procedures and preliminary results for videolaparoscopic presacral neurectomy as part of the surgical treatment of endometriosis associated with intractable dysmenorrhoea. Observational study with follow up for at least one year. Subspecialty practice: Endometriosis Clinic and Centre for Special Pelvic Surgery. Eighty five women (18-45 years) with endometriosis and intractable pain, referred because medical and surgical management had failed. Subjects without a central (midline) component to their discomfort were excluded. Excision and vaporization of endometriotic pathology was followed by presacral neurectomy. During surgery, severity of endometriosis was assessed using revised American Fertility Society scoring. Overall pelvic pain and dysmenorrhoea relief were determined by office visit, telephone interview and questionnaire at a minimum of one year postoperatively. There were no operative complications and all women left hospital within 24 h of surgery. Overall pain relief was reported by 49 (94%) of 52 patients followed. The other three subjects noted no pain abatement. Dysmenorrhoea was reduced in 48 (92%) whereas four (8%) women claimed no relief. Laparoscopic presacral neurectomy is an option for treating dysmenorrhoea and pelvic pain in selected women, but is indicated only if medical management has failed. Videolaparoscopic presacral neurectomy using the CO2 laser is safe in trained hands. Pain relief achieved is within the range reported for laparotomy.


Laparoscopic treatment of infiltrative rectosigmoid colon and rectovaginal septum endometriosis by the technique of videolaparoscopy and the CO2 laser.

To present the technique and results of videolaparoscopy and the CO2 laser as a treatment for deep, infiltrative endometriosis of the rectovaginal septum, uterosacral ligaments, pouch of Douglas and anterior wall of the rectosigmoid colon. Observational study with 1-5 year follow up. Sub-specialty practice: Endometriosis clinic and centre for special pelvic surgery. 185 women, aged 25-41 years. All had pelvic endometriosis and were referred because of the failure of previous medical and/or surgical treatment. Vaporization and excision of endometriotic implants and nodules, ureterolysis, ureteric stents, laparoscopic anterior rectal wall resection and reanastomosis, presacral neurectomy, laparoscopic hysterectomy, salpingo-oophorectomy and appendicectomy using the CO2 laser. 174 patients were followed for 1-5 years after surgery by office visit questionnaire or telephone interview. Eleven were lost to follow-up. 175 patients were discharged within 24 h. Nine with bowel perforations and one with a partial bowel resection were discharged 2-4 days postoperatively. Two patients required ureteric stents, which were removed 6 weeks postoperatively without sequelae. 162 women reported moderate to complete pain relief (145 after one procedure, 13 after two and four after three). 12 reported persistent or worse pain following the surgery. Seven eventually underwent total hysterectomy, four had bowel resections and one had a salpingo-oophorectomy. Of 61 with infertility, 25 achieved pregnancy. Postoperative complications included shoulder pain, anterior abdominal wall ecchymosis, urine retention and dyschezia for one to two weeks. Our experience suggests that rectosigmoid colon and infiltrative rectovaginal septum endometriosis can be effectively treated via videolaparoscopy in the hands of experienced endoscopic gynaecologists.


Cone biopsy: has endocervical sampling a role?

To investigate the sensitivity, specificity and predictive value of endocervical sampling in women with abnormal cervical smears. A randomized study of two methods of endocervical sampling. Colposcopy clinic at Aberdeen Royal Infirmary. 100 women with abnormal cervical smears selected for cone biopsy according to current colposcopy criteria. 53 women were randomized to have endocervical sampling with the Kevorkian curette and 47 to have sampling with the Medscand endocervical brush. Cytology and histology results from endocervical sampling compared with cone biopsy histology. The overall sensitivity of endocervical sampling was 56%, with a false negative rate of 44% and a negative predictive value of 26%. Endocervical sampling should not influence management when colposcopy is unsatisfactory.


Genital tract infections associated with the intrauterine contraceptive device can be reduced by inserting the threads into the uterine cavity.

To study the influence of the position of the threads of an intrauterine contraceptive device (IUCD) on the development of genital tract infection. A multicentre randomized controlled trial. Women requesting an IUCD. The women were randomized to be fitted with an IUCD either with the threads contained in the uterine cavity (threads-up group) (n = 208) or passing through the cervix to the vagina in the usual way (threads-down group) (n = 237). Multiple centre study with follow-up at three months, 1 and 2 years. At the final visit 'missing' threads were retrieved using a disposable instrument (Retrievette). The occurrence of infection in the lower or upper genital tract. 63 women in the threads-up group and 78 in the threads-down groups dropped out. Previous gynaecological infection was reported by 21 and 48 women in the threads-up and threads-down group, respectively (odds ratio 0.44, 95% CI 0.24 to 0.79), 21 and 53 subjects had signs of infection at gynaecological examination (odds ratio 0.39, 95% CI 0.21 to 0.69) and a wet-smear was pathological in 33 and 79 (odds ratio 0.38, 95% CI 0.23 to 0.61). In the threads-up group the vaginal pH was also lower at the final check up after 2 years. Spontaneous descent of the threads occurred in 11% of the threads-up group and in six women in the threads-down group the threads were in the cervix. In 93 women the threads were easily retrieved by means of the Retrievette, four women insisted on the threads remaining in the uterus and in 18 thread removal was performed under local or general anaesthesia. Infectious complications in women using an IUCD are more frequent if the threads lead from the uterine cavity to the vagina. This problem can be reduced by inserting the threads so that they remain entirely within the uterine cavity, a feasible procedure now that an effective instrument for IUCD thread retrieval is available.


Stimulation of vasopressin release in women with primary dysmenorrhoea and after oral contraceptive treatment--effect on uterine contractility.

To study aspects of the aetiology of primary dysmenorrhoea and mechanisms underlying the therapeutic effect in this condition of an oral contraceptive. Intrauterine pressure was recorded before and during infusion of hypertonic saline (5% NaCl, 0.06 ml/kg/min) over 75 min on the first day of bleeding in women with dysmenorrhoea and after 3 weeks of oral contraceptive treatment. Plasma sampling every 15 min of ongoing infusion for the estimation of osmolality, arginine vasopressin, oxytocin and the prostaglandin (PG) F-metabolite, 15-keto-13,14-dihydro-PGF2 alpha. Ten healthy nulliparous women with moderate to severe primary dysmenorrhoea. Plasma levels of posterior pituitary hormones and the PGF-metabolite. Total pressure area (TPA) of the recording curve. In dysmenorrhoea before infusion the plasma concentration of vasopressin was in mean 2.18, oxytocin 5.05 and the PGF-metabolite 321.5 pmol/l, and the TPA 3.8 kPa x 10 min. After oral contraceptive treatment the vasopressin level and the TPA were significantly reduced. At both sessions apart from intensifying the pain, the saline infusion increased vasopressin and oxytocin levels as well as the TPA, whereas the concentration of the PGF-metabolite at both sessions decreased. Confirmation is provided of the elevated secretion of arginine vasopressin and PGF2 alpha, as well as increased uterine activity in primary dysmenorrhoea. The observations are in agreement with the concept that a lowered level of vasopressin and a decreased uterine activity contributes to the beneficial effect of OCs in the condition. Stimulation of the secretion of vasopressin increases the uterine activity and symptoms of primary dysmenorrhoea, but results suggest that this effect does not involve a mechanism of increased PGF-synthesis. The role of oxytocin in dysmenorrhoea can not yet be defined.