The effects of stimulus frequency and recording site on the amplitude and latency of multichannel cortical auditory evoked potential (CAEP) component N1.

Magnetoencephalographic (MEG) applications in auditory evoked field (AEF) recordings have demonstrated that both tonotopicity and amplitopicity exist in the auditory cortex. The present study was conducted to determine whether previously reported characteristics of the AEF could be identified in multichannel cortical auditory evoked potential N1e (e.g., the electrical correlate of the magnetically recorded N1m) component recordings. Multichannel auditory evoked potentials from 11 young normal adults were collected after monaural tone burst stimuli of 250, 1000, and 4000 Hz. Results demonstrated that N1e amplitudes after stimulation at 250 Hz were significantly larger than those obtained after stimulation at 1000 or 4000 Hz. These frequency-specific differences existed for latency as well. Responses obtained after stimulation at 250 Hz were, on the average, 13 msec longer than those obtained after stimulation at 1000 or 4000 Hz. Also, contralateral latencies were significantly shorter than ipsilateral latencies. Although the significant frequency-specific amplitude results support the findings of previous investigators, the frequency-related latency differences have not been described. An explanation of these differences may exist in the spatial differences in the reception areas for low- and high-frequency tones in the primary auditory cortex.


Detectability of transient and sinusoidal otoacoustic emissions.

An analysis is presented of the detectability of the two types of otoacoustic emissions being considered for use in clinical tests of hearing. It is estimated that, for equal emission levels and equal probability of error, measurement of distortion-product emissions can be made at least 30 times faster than transient-evoked emissions using current techniques.


Telephone usage in the hearing-impaired population.

The purpose of this project was to determine if the hearing-impaired population reports satisfaction with their ability to converse over the telephone in both aided and unaided situations. For this study, we surveyed 104 hearing-impaired persons using a 43 item questionnaire that investigates problems that hearing-impaired people encounter when using the telephone. The questionnaire also probes the solutions that hearing-impaired people use for overcoming these problems. Of the 91 respondents who wear hearing aids, 55% use their aids while operating the telephone. However, 70% of these respondents reported that coupling the hearing aid to the telephone is problematic. Use of a telephone amplifier was reported by 73% of the sampled population. The majority of the subjects, 75%, indicated an interest in improvements in telephone communications for hearing-impaired people.


Patient experiences with multiband full dynamic range compression.

This investigation compared performance for 18 experienced hearing aid patients with a multiband full dynamic range compression hearing device and their previously worn linear or automatic gain control hearing aids. Performance was evaluated using a variety of clinical tests. These included functional gain and dynamic range measurements, speech recognition, and real ear measurements. Patients rated their performance with the multiband compression device and their previously worn aids on a rating scale pertaining to a variety of real life listening situations. Statistical analysis of data derived from test results shows significantly improved performance on all measures using the multiband compression aid over their conventional aids. Patients rated their performance higher with the compression instrument than with the conventional aids. Differences in performance on clinical tests and subjective patient responses appear to be related to the different signal processing schemes used in the two groups of devices.


A comparison of sound quality judgments for monaural and binaural hearing aid processed stimuli.

Fifteen adults with bilaterally symmetrical mild and/or moderate sensorineural hearing loss completed a paired-comparison task designed to elicit sound quality preference judgments for monaural/binaural hearing aid processed signals. Three stimuli (speech-in-quiet, speech-in-noise, and music) were recorded separately in three listening environments (audiometric test booth, living room, and a music/lecture hall) through hearing aids placed on a Knowles Electronics Manikin for Acoustics Research. Judgments were made on eight separate sound quality dimensions (brightness, clarity, fullness, loudness, nearness, overall impression, smoothness, and spaciousness) for each of the three stimuli in three listening environments. Results revealed a distinct binaural preference for all eight sound quality dimensions independent of listening environment. Binaural preferences were strongest for overall impression, fullness, and spaciousness. Stimulus type effect was significant only for fullness and spaciousness, where binaural preferences were strongest for speech-in-quiet. After binaural preference data were obtained, subjects ranked each sound quality dimension with respect to its importance for binaural listening relative to monaural. Clarity was ranked highest in importance and brightness was ranked least important. The key to demonstration of improved binaural hearing aid sound quality may be the use of a paired-comparison format.


The effects of limiting the number of Nucleus 22 cochlear implant electrodes programmed on speech perception.

The purpose of this double-blind study was to evaluate systematically the effects of varying programmed electrodes on speech perception. The performance of five subjects implanted with the Nucleus 22-electrode cochlear implant was compared on the Four-Choice Spondee test, the Central Institute for the Deaf Sentence test, and Speech Tracking across the following conditions: (1) five most apical electrodes eliminated from the subject's MAP (stimulus parameters); (2) five most basal electrodes eliminated from subject's MAP; (3) the middle five electrodes eliminated from subject's MAP; and (4) subject's current MAP. Statistically significant differences were found for the Four-Choice Spondee test and both the auditory-only and auditory-plus-lipreading Speech Tracking measures. Three subjects demonstrated poorer performance on all test measures when the five electrodes from the apical portion of the array were not programmed. Two subjects performed equally well, regardless of MAP condition. Group means for all test measures present a trend of consistently poorer performance when the -5 Apex MAPs were utilized. A subjective rating scale was consistent with the perceptual tests, with all subjects best liking their current MAP and least liking the -5 Apex MAP. Results suggest that for some subjects, a fixed place code may control their ability to use spectral information for speech discrimination. For these subjects, first formant information (F1) traditionally coded on the most apical electrodes could not be utilized as effectively when coded on the adjacent middle electrodes.


Evaluation of a dual-channel full dynamic range compression system for people with sensorineural hearing loss.

This article describes an evaluation of an in the ear hearing aid, which applies fast-acting full dynamic range compression independently in two frequency bands. This can compensate for the loudness recruitment typically associated with sensorineural hearing loss. The crossover frequency between the two bands and the gain and compression ratio in each band are programmable to suit the individual patient. Twenty subjects with moderate sensorineural hearing loss were tested in a counterbalanced order using the aid programmed as a linear amplifier (condition L) and as a two-band compressor (condition C). All subjects were fitted binaurally. Subjects were also tested without hearing aids (condition U) and using the hearing aids that they normally wore (condition Own). Speech intelligibility was measured in quiet at three sound levels (50, 65, and 80 dB SPL), and speech reception thresholds (SRTs) in 12-talker babble were measured under monaurally and binaurally aided conditions, with the speech and babble both coincident and spatially separated. In condition C, speech intelligibility in quiet was high at all sound levels. Speech intelligibility at the two lower levels decreased in condition L, and decreased still further in conditions Own and U. Condition C gave, on average, better speech intelligibility in babble (lower SRTs) than conditions L, Own, or U. The advantage of condition C over condition L varied across subjects and was correlated with the dynamic range for tones at high frequencies; small dynamic ranges were associated with greater benefit from compression. A significant advantage for binaural aiding was found both when the speech and noise were spatially separated and when they were coincident. The binaural advantage was similar for the C and L conditions, indicating that the independent compression at the two ears did not adversely affect the use of binaural cues. Questionnaires on the subjects' experiences with the aids in everyday life indicated that they generally preferred condition C over condition L.


The effects of intervention strategy on self-perception of hearing handicap.

The purpose of this study was to determine whether participation in a counseling-based aural rehabilitation program would result in greater reduction of self-perceived hearing handicap than hearing aid use alone. Thirty-one postlingually hearing-impaired adults were placed into three groups after audiological evaluation. The first group received hearing aids and participated in a counseling-based aural rehabilitation (AR) program. The second group received hearing aids only. The third group received neither hearing aids nor counseling-based AR. The Hearing Handicap Inventory for the Elderly was administered to all subjects before audiological evaluation and again to all subjects 2 mo after receipt of hearing aids for the experimental groups. For both experimental groups, self-perception of hearing handicap was significantly reduced as a function of intervention when measured on any of the three Hearing Handicap Inventory for the Elderly scales, whereas there was no change in self-perception of hearing handicap for the control group on any scale. In addition, there was weak but significant evidence that participating in the counseling-based AR program in addition to hearing aid use resulted in a greater reduction of self-perceived hearing handicap than did hearing aid use alone.


High-frequency threshold measurements using insert earphones.

Several recent studies have reported large intersubject variability of high-frequency thresholds measured with circumaural earphones. In the present study, high-frequency thresholds of 10 subjects were measured with circumaural (Sennheiser HD-250) and insert (Etymotic ER-1) earphones at 10, 12, 14, and 16 kHz. Overall results show significantly smaller variability of the threshold data obtained with insert earphones than with circumaural earphones. The above data indicate that insert earphones may be more suitable for high-frequency testing than circumaural earphones.


Occurrence of auditory evoked field (AEF) N1M and P2M components in a sample of normal subjects.

A great deal of information about the characteristics of components N1m and P2m of the auditory evoked cortical fields (AEFs) has accumulated since the late 1970s. However, a number of fundamental issues have not been addressed. For instance, some previous investigators have suggested that P2m is present consistently in normals, whereas others suggest that when present, P2m is small in amplitude. Preliminary observations in this laboratory suggested that P2m is not observed consistently in normal subjects. Therefore, the specific aim of this investigation was to estimate the frequency of occurrence of the contralaterally recorded N1m and P2m after stimulation of right and left ears in normal subjects. Results demonstrated N1m to be present in all circumstances. Consistent with our preliminary observations, P2m was often absent, and moreso after stimulation of the left ear.


Signal to noise constraints on maximum length sequence auditory brain stem responses.

In conventional auditory brain stem response (ABR) testing, the stimulus rate must be low enough that the responses do not overlap. By using stimulus patterns derived from the pseudorandom binary series known as maximum length sequences (MLSs), it is possible to stimulate at mean rates of hundreds of clicks per second, and extract the responses. It has been suggested that this could reduce test time appreciably, but there is reason to believe that the MLS ABR is intrinsically noisier than conventional averaging. To test this premise, 10 ears were tested with conventional ABR procedures and with MLS ABRs having 2, 4, and 8 times as many stimuli per second as the conventional condition. Noise levels in control runs were in agreement with predictions. With a 40 dB nHL stimulus, wave V amplitude decreased in the MLS ABRs to the extent that none of the MLS conditions was as efficient as the conventional ABR. Any assessment of the value of MLS ABRs in reducing test time must take into consideration the higher noise levels inherent in this procedure.


The effects of stimulus rate on detectability of the auditory brain stem response in infants.

This study was undertaken to determine the feasibility of using a fast stimulus rate for auditory brain stem response (ABR) hearing screening in infants. Eighty-four neonates and infants with postconceptional ages (PCA) from 30 to 78 weeks with clear ABRs to click rate of 40/sec at 30 dB HL were retested at 90/sec. Ninety-two percent of infants with PCA > 42 weeks had a clearly identifiable ABR at the 90/sec rate. In contrast, 71% of the infants with PCA between 37 and 42 weeks, and only 50% of the infants with PCA < 37 weeks, had clearly identifiable ABRs at 90/sec. Thus, a 90/sec stimulus rate was not practical on infants < 43 weeks PCA. Accordingly, ABR detectability was assessed to 40 dB clicks at 70/sec compared to the 40/sec rate on 20 infants between 33 and 42 weeks PCA. ABRs were detectable on 85% of this group, which suggests that these parameters may be more reasonable, but further data are needed. ABR measures for hearing screening on infants > 42 weeks and children can be satisfactorily performed at stimulus rates up to 90/sec; however, infants who fail the screening when using a fast stimulus rate should have a repeated measurement at a slower rate to rule out a false positive result.


Evaluation of two clinical versions of the articulation index.

The present study evaluated the predictive accuracy of two clinical versions of the articulation index (AI). AI calculations were made and word recognition scores obtained for normal-hearing young adults and elderly hearing-impaired listeners in quiet and in a noise background. The impaired listeners were also evaluated for both aided and unaided listening conditions, with the aided AI values adjusted by the measured real ear insertion gain for each listener. Results revealed that the two clinical AI procedures yielded virtually identical values, and both were accurate predictors of speech recognition performance for unaided conditions. Aided speech recognition performance was predicted less accurately by both methods, especially when a noise background was present. On the other hand, within a given listener, both AI methods were valid indicators of the relative performance across listening conditions.


Measures of tinnitus: step size, matches to imagined tones, and masking patterns.

Measures of the pitch (0.2% step) and loudness (2 dB step) of tinnitus were obtained using a forced-choice double-staircase procedure. In the first experiment, for seven subjects with tinnitus, the difference limen of pitch and loudness matches made to tinnitus within a single block of trials was not significantly different from that of the same measurements made to comparable external stimuli. In the second experiment, subjects matched the pitch of real and imagined tones. For 3 of 7 subjects with tinnitus and for 2 of 14 normal-hearing subjects, the difference limens were nearly equal. In the first experiment, therefore, three of the subjects with tinnitus might have matched to an imagined tone and not to their tinnitus. In the third experiment, thresholds of tones near the presumed tinnitus frequency were measured. Thresholds were approximately equal in the presence of the tinnitus. However, in the presence of a masking tone at the presumed tinnitus frequency and level, thresholds were unequal. Thus, tinnitus did not behave as a tonal masker.


Test/retest reliability of distortion-product and transiently evoked otoacoustic emissions.

Otoacoustic emissions can be used to study cochlear function in an objective and noninvasive manner. These features of emitted responses have stimulated a great deal of investigation into the utility of evoked emissions as clinical tests of hearing. One practical and essential aspect of any clinical measure is the consistency of its result upon repeated testing of the same individual (i.e., its test/retest reliability). The goal of the present work was to conduct a systematic study of the test/retest reliability of the two evoked emission types, the transiently evoked and the distortion-product otoacoustic emissions, that have the greatest promise of becoming clinically useful. Toward this end, the short- and long-term reliabilities of these two response measures were examined in 12 normally hearing adults. The results of these experiments showed that the consistency of both measures of evoked otoacoustic emissions was generally excellent.


Distortion-product otoacoustic emissions in human newborns and adults.

Cubic distortion-product otoacoustic emissions (DPEs) may have clinical and research applications. We reliably recorded DPEs at some frequencies in all of the normal-hearing human adults and newborns tested. Adult and newborn DPEs were of comparable amplitude, with the exception that a prominent dip between 1 and 3 kHz in the adult data was less evident in the newborn data. DPE amplitude was a linear function of the intensity of the eliciting primary stimuli. The slopes of the linear input-output functions increased with increasing frequency. Except at the highest frequencies assessed, adult input-output functions were steeper than newborn input-output functions.


Towards the validation of aural acoustic immittance measures for diagnosis of middle ear effusion in children.

Acoustic admittance testing was done on the ears of two groups of children. The first group was comprised of children undergoing myringotomy and tube surgery for treatment of chronic or recurrent otitis media, and the second group was comprised of hospital outpatients who were unscreened with respect to a history of middle ear disease and who were more representative of children in the general population. The admittance measures were then analyzed with respect to middle ear status (effusion versus no effusion) as determined by the surgeon (surgery group) and by validated otoscopy (outpatient group). Based on the data from the surgery group, the best admittance criteria for the identification of middle ear effusion were determined and then tested with respect to the data from subjects in the outpatient group. Sensitivity and specificity of several different criteria were similar. The role of prevalence of disease and the value of admittance measures such as gradient and acoustic reflex are discussed in the context of diagnostic testing in clinical or research protocols as well as in the context of immittance screening programs.


Attenuation values for a supra-aural earphone for children and insert earphone for children and adults.

Earphone attenuation values were determined for 17 children (6-14 years old) using supra-aural (TDH-49P/Model 51 cushion) and insert earphones (E-A-Rtone 3A) terminated by an E-A-Rlink 3A (for normal size ear canals) or E-A-Rlink 3B (for small size ear canals) foam eartips, and for 10 adults having small ear canals using insert earphones and E-A-Rlink 3B foam eartips. The test signals were 1/3-octave bands of noise presented in a diffuse sound field (re: ANSI S12.6-1984). The supra-aural earphone attenuation values for the children were slightly higher (more attenuation) or similar to reported adult values, and always lower (less attenuation) compared with insert earphone/E-A-Rlink 3A (IE/3A) or 3B (IE/3B) values for both children and adults. The IE/3B attenuation values were similar between the children and adults and provided slightly more attenuation than the IE/3A. Overall, the results indicated that the ANSI S3.1-1991 maximum permissible ambient noise levels allowed in a test room for ears covered testing with a supra-aural earphone, which were determined using adult values, are appropriate for testing children. Future revisions of ANSI S3.1-1991 may include maximum permissible ambient noise levels for testing with insert earphones. The IE/3A and IE/3B attenuation values could be used for that purpose. In the meantime, because more attenuation was provided by the IE/3A and IE/3B, they can be used for testing both children and adults in higher ambient noise levels than specified in ANSI S3.1-1991.


A look at ear canal changes with jaw motion.

Two procedures were used with one subject to examine changes in the ear canal with jaw motion. Silicone ear impressions were examined to measure the effect of jaw position. Magnetic resonance imaging was used to define the three-dimensional structure of the canal and visualize key underlying tissue. Results showed that inexpensive impressions can detail changes in the cartilaginous region of the canal. Approximately a 25% change in this subject's ear canal with different jaw positions was observed in the anterior/posterior plane with essentially no change in the superior/inferior plane. This is likely related to asymmetric stress from action of the mandibular condyle on neighboring cartilaginous tissue. Solutions to jaw motion-induced feedback problems are suggested.


Molecular interactions of anaesthetics with biological membranes.

1. There is not yet a consensus as to which of the neuronal membranes, which molecular component of any particular membrane or what specific function of the membrane is critical for general anaesthesia. 2. However, when considering anaesthetic effects on different synapses, with neurotransmitter receptors, ion channels etc., the unifying central concept is action at a membrane level. 3. This paper will review the general evidence for this unifying hypothesis, and consider the apparent exceptions and limitations. 4. The membrane hypothesis is usually stated in the form of the Meyer and Overton "rule" relating anaesthetic potency to hydrophobic solubility. 5. The relationship applies to inhaled anaesthetics with potencies over a 100,000-fold range and has been described as one of the most powerful correlations in biology. 6. Finding additional compounds that confirm this correlation is not likely to elucidate further the anaesthetic mode of action, and concentrating on the apparent exceptions to the hypothesis may prove to be a better approach. 7. The apparent exceptions to the membrane hypothesis include some of the physiological and convulsant gases as well as higher members of a homologous series of hydrophobic compounds above the so-called "cut-off" effect. 8. The apparent limitations include two of the most widely used clinical agents--enflurane and isoflurane. 9. This paper will include some new data characterizing the anaesthetic site of action using a diverse group of anaesthetics (including some of the exceptions already mentioned). 10. The evidence is against an earlier hypothesis that there is a bimodal distribution of the molecular sites.


The pharmacology of vesamicol: an inhibitor of the vesicular acetylcholine transporter.

1. Vesamicol (2-[4-phenylpiperidino] cyclohexanol) inhibits the transport of acetylcholine into synaptic vesicles in cholinergic nerve terminals. 2. Recent pharmacological studies of the effects of vesamicol on skeletal neuromuscular transmission have revealed a pattern of activity for the compound consistent with the neurochemical observation of the mechanism of action of the compound. 3. Pharmacological manipulation of vesicular acetylcholine transport has been used to investigate the recycling and mobilization of synaptic vesicles within cholinergic nerve terminals. 4. In addition to its effects on vesicular acetylcholine transport, vesamicol also possesses some sodium channel and alpha-adrenoceptor blocking activity. 5. Vesamicol clearly represents a unique tool for investigating presynaptic mechanisms in cholinergic nerve terminals.


Dopamine: a stress modulator in the brain and gut.

1. Central dopamine (DA) exhibits large and rapid responses to stress challenge, particularly in the mesolimbic DA tract and, to a lesser degree, in the mesocortical tract. 2. Over the last few years, there has emerged an increasing role for peripheral DA, especially gastrointestinal DA, as a modulator of gastroduodenal injury consequent to stress exposure. 3. Evidence has accumulated which strongly supports a role for DA as an endogenous gastroprotective element and it appears that the dopaminergic "brain-gut axis" is a critical determinant of gastroduodenal mucosal integrity in the stress-challenged gut.


Significance of gamma-hydroxybutyric acid in the brain.

1. Administration of the endogenous compound gamma-hydroxybutyric acid (GHB) can induce a sleep-like state in experimental animals and, indeed, it has been used as a general anaesthetic in clinical medicine. 2. Although GHB appears to be a CNS depressant, there is evidence it possesses epileptiform activity resembling petit mal epilepsy. In the brain GHB is evidently derived from GABA, the final step being catalyzed by succinic semialdehyde reductase, a cytosolic NADP(+)-dependent enzyme. 3. Two different oxidoreductases, GHB dehydrogenase and hydroxyacid-ketoacid dehydrogenase, acting independently, are responsible for the reverse reaction when GHB is being metabolically inactivated. 4. Brain contains a Na(+)-dependent GHB uptake system which exhibits two components, one with a Km of 46 microM and the other with a Km of 325 microM. GHB also binds to receptor sites in brain homogenates and exhibits two distinct affinities. One binding site displays a Kd of 95 nM whereas the second site has a Kd of 16 microM. Binding to both sites is inhibited in the presence of NCS-382, a GHB receptor antagonist. 5. GHB might play a role as a neurotransmitter, particularly being involved in influencing dopamine release in the substantia nigra.


FAST and SLOW ipsilateral and contralateral spinal reflexes in the neonate rat are modulated by 5-HT.

1. Three ipsilateral (MSR, PSR, IPSI SLOW) and two contralateral segmental reflexes (CON FAST, CON SLOW) were recorded from L4 or L5 ventral roots of the neonate rat spinal cord in vitro. MSR, PSR and CON FAST were evoked from lower threshold afferents; more intense stimulation evoked IPSI SLOW and CON SLOW. 2. Kainate/AMPA receptors were involved in mediation of MSR, PSR, CON FAST, IPSI SLOW and CON SLOW and NMDA receptors in mediation of CON FAST, IPSI SLOW and CON SLOW. 3. All five reflexes were depressed by 5-HT (IC50 1.2-7.9 microM; order of sensitivity, CON SLOW > CON FAST = IPSI SLOW > MSR = PSR); and by 5-CT (IC50 1.9-8.8 nM; order of sensitivity, MSR > IPSI SLOW = CON FAST = CON SLOW > PSR). alpha-Me-5-HT also depressed all five reflexes. 4. Dipropyl-5-CT selectively depressed MSR and CON SLOW (IC50 90-170 nM) but was less potent than 5-CT. 8-OH-DPAT selectively depressed MSR (IC50 1.1 microM), IPSI SLOW and CON SLOW (IC50 5.7-7.6 microM), while methylsergide depressed only MSR (IC50 26 nM). 5. Phenyl biguanide and m-chlorophenyl biguanide (5-HT3 receptor agonists) had no significant effects on any reflex. 6. It is concluded that a 5-HT1-like receptor mediates depression of the MSR. A different receptor or a mixed population of receptors, but not 5-HT3 receptors, mediate inhibition of PSR, CON FAST, IPSI SLOW and CON SLOW.


Evidence that the inhibition of ATP release from sympathetic nerves by adenosine is a physiological mechanism.

1. Perfusion with the P1-purinoceptor agonist adenosine (1-500 microM) greatly reduced the stimulation-induced release of ATP and the initial contractile phase of the response of the guinea pig vas deferens to field stimulation. 2. The inhibitory effects of adenosine (100 microM) were readily antagonised by the P1-purinoceptor antagonist, 8-phenyltheophylline (10 microM). 3. Dipyridamole (10 microM), inhibited the stimulation-evoked release of ATP from the guinea pig vas deferens and reduced the initial component of contraction. 4. These results support the view that adenosine, resulting from ectoenzymatic breakdown of ATP released as a cotransmitter from sympathetic nerve terminals, acts as a physiological prejunctional regulator of transmitter release.


Influences of changes in calcium concentration and verapamil on the cardiac depressant effect of ethanol in cat papillary muscle.

1. In isolated cat heart papillary muscle electrically driven at a constant rate the depressant effects of increasing concentrations of ethanol on peak tension developed (PTD) was studied in Ringer-Locke solution with different calcium concentrations and with the addition of verapamil. 2. Ethanol induced a concentration dependent decrease in PTD that was significantly greater for each concentration of ethanol in hypocalcic medium (1.1 mM) than in normocalcic medium (2.2 mM). 3. In normocalcic (2.2 mM) medium, verapamil (5.1 x 10(-4) mM) plus ethanol (48.6 and 97.2 mM) produced a decrease in PTD to values significantly greater than those obtained by the addition of ethanol and verapamil alone. Therefore a potentiation of the effects of ethanol by verapamil was observed when both drugs act simultaneously. 4. In hypercalcic medium (4.4 mM), verapamil plus ethanol (48.6 and 97.2 mM) produced a slight decrease in PTD that was significantly less than that observed in normocalcic and hypocalcic mediums. 5. In hypocalcic medium (1.1 mM) verapamil plus ethanol (48.6 and 97.2 mM) produced a decrease in PTD that was of the same relative magnitude (%) as that observed in normocalcic medium. However no potentiation of the combined effects of verapamil plus ethanol was observed in hypocalcic medium.


Pharmacological characterization of a new purinergic receptor site in rabbit aorta.

1. The pharmacological properties of a vasodilating purine-activated receptor that is not a P1 or P2-purinoceptor were investigated. 2. In rabbit isolated thoracic aorta precontracted with noradrenaline, ATP induced a 50% relaxation at 0.25 mM (EC 50%); in the absence of endothelium, EC 50% was 2.5 mM. 3. Adenosine induced a relaxation that was not different in both the presence and absence of endothelium, being EC 50% 0.48 and 0.37 mM, respectively. 4. The potent and selective P2y-purinoceptor agonist 2-methylthio-ATP (0.03-10 microM) induced a relaxation only in the presence of endothelium. 5. In de-endothelialized aorta, 8-phenyltheophilline (8-PT: P1 antagonist) and 3,7-dimethyl-1-propargylxanthine (DMPX: A2 antagonist) did not antagonize ATP- and adenosine-induced relaxation. 6. The present data support the presence of a new site of action for purines in rabbit isolated thoracic aorta. 7. A P3 subtype of purinoceptor, that may be identified in the hypothesized "nucleotide" receptor, is proposed.


Autoradiographic analysis of dopamine D1 receptors in the gerbil brain following transient cerebral ischemia.

1. We studied the postischemic time-course of dopamine D1 receptors in selectively vulnerable areas in the gerbil using receptor autoradiography. 2. [3H]SCH 23390 was used to label dopamine D1 receptors and transient cerebral ischemia was induced for 10 min. 3. [3H]SCH 23390 binding showed no significant alteration in selectively vulnerable areas at an early stage (1-24 hr) of recirculation. Thereafter, [3H]SCH 23390 binding showed a significant reduction in most selectively vulnerable areas 48 hr or 7 days of recirculation. The ventromedial striatum and dentate gyrus which were resistant to ischemia also exhibited a significant reduction in [3H]SCH 23390 binding. 4. Especially, marked reduction was noted in the dorsolateral striatum. However, this reduction in the dorsolateral striatum was not seen early in the recirculation prior to morphological neuronal damage. 5. The result suggests that transient cerebral ischemia can cause a severe reduction in dopamine D1 receptors in most selectively vulnerable areas. Furthermore, they suggest that dopamine D1 transmission is not always responsible for the evolution of ischemic brain damage. 6. These findings are discussed in relation to the mechanism of ischemic brain damage.


Effects of S-11701 on accumulation, release and metabolism of norepinephrine in isolated canine saphenous veins.

1. The effects S-11701 ([morpholinyl-2)-methoxy]-8-tetrahydro-1,2,3,4 quinoline) on accumulation, overflow and metabolism of [3H]norepinephrine were investigated in isolated canine saphenous veins. 2. Saphenous veins were incubated with [3H]norepinephrine in the absence or the presence of S-11701; the drug caused a concentration-dependent inhibition of the tissue content of [3H]norepinephrine and its metabolites, except for 3-methoxy-4-hydroxymandelic acid (VMA). 3. In helical strips of canine saphenous veins previously incubated with [3H]norepinephrine and then suspended for isometric tension recording and measurement of the overflow of labelled transmitter and its metabolites, S-11701 (30 microM) significantly increased the spontaneous efflux of total 3H; this effect was almost exclusively due to an augmentation of the efflux of [3H]DOPEG. 4. During electrical stimulation (9 V, 1 Hz), S-11701 at 1 microM slightly increased the overflow of extraneuronal norepinephrine metabolites without affecting the contractile response. At the higher concentration (30 microM) the compound increased the contractive response and the overflow of 3H; the latter was due mainly to an increase in [3H]DOPEG and, to a lesser extent, in [3H]norepinephrine. 5. DMI (1 microM) did not interfere with the effects of S-11701 on DOPEG efflux. 6. These experiments indicate that in the canine saphenous vein, S-11701 causes a concentration-dependent inhibition of neuronal accumulation of [3H]norepinephrine. At higher concentrations, S-11701 enters the adrenergic nerve terminals independently of the neuronal amine carrier and displaces [3H]norepinephrine from its storage sites.


The potentiating effect of KC-404 on prostacyclin-induced vasodilation in isolated human cerebral artery.

1. KC-404 (10(-9)-10(-6) g/ml) produced concentration-dependent relaxations in human middle cerebral arteries contracted with prostaglandin F2 alpha. 2. KC-404 (10(-8) and 10(-7) g/ml) has the ability to significantly potentiate prostaglandin I2-induced relaxations in human middle cerebral arteries. 3. KC-404, at least in low concentrations, may elicit human cerebral vasodilation predominantly by potentiating relaxant responses to prostaglandin I2 produced spontaneously in vascular wall. 4. KC-404 is expected to increase cerebral blood flow at least by dilation of major cerebral arteries, and this agent may be beneficial for the treatment of cerebrovascular disorders.


Microtubular tau protein after cocaine in cultured SH-SY5Y human neuroblastoma.

1. SH-SY5Y, a human neuroblastoma cell line, was used as a tissue culture model to examine the hypothesis that cocaine may affect the metabolism of tau protein which stabilizes microtubules and promotes microtubule assembly. 2. Cocaine hydrochloride (10(-9)-10(-3) M) caused dose-dependent reductions in cell number, with 10(-3) M causing 28% reduction after 48 hr. 3. This drug also decreased tau protein (50 Kd) in the cytoplasmic (supernatant) as well as the membrane (pellet) fraction after 48-hr treatment.


Effect of the length of degenerating phrenic nerve fibres on the anaphylactic contraction of the diaphragm.

1. The effect of denervation on the anaphylactic contraction of the diaphragm from actively sensitized guinea pig has been studied. 2. The section of the phrenic nerve took place at cervical and thoracic levels. The sensitization of the animal took place several days before sectioning, simultaneously with denervation and after denervation. 3. The anaphylactic contractions were observed from the fourth day after thoracic denervation, and from the sixth day when denervation was in the cervical region. 4. The hypersensitivity to ACh in the denervated diaphragmatic muscle was present 24 hr after sectioning the phrenic nerve and reached its maximum 3-4 days after. 5. These results support the idea that denervation caused some changes in the membrane of the skeletal muscle fibres to allow the fixation of antibodies. These denervation changes are dependent on the length of the peripheral nerve left to degenerate. Anaphylactic contractions appeared earlier in those animals where phrenic nerve sections were closer to the diaphragmatic muscle.


Do central mechanisms participate in the thermoregulatory activity of prazosin?

1. Prazosin (PRA) was used in febrile (LPS; 1 mcg/kg; i.v.) and normothermic rabbits at ambient temperatures (Ta) of 5, 19 and 28 degrees C. This drug was given i.v. in the form of an infusion at a rate of 0.75 mg/kg/3 hr. 2. In normothermic animals, PRA produced significant hypothermia mainly at Ta of 5 and 19 degrees C. In a cold environment, the hypothermic effect of PRA was associated with inhibition of metabolic rate and evaporative heat loss. 3. Infusion of this drug significantly prevented the LPS-induced fever in all experimental conditions. In the cold environment, a drop in body temperature was correlated with an inhibition of metabolic rate; in the thermoneutral environment, antipyresis was associated with an increase in heat dissipation from the ear-skin area; in the hot environment, the correlation between antipyresis and mechanisms of heat dissipation was much less clear. 4. The possible action of PRA on the effector part of the central thermoregulatory system is discussed.


Involvement of swimming-induced acute stress in the sensitivity of rat vs deferens to norepinephrine.

1. The effects of swimming-induced stress on rat sensitivity to norepinephrine were studied. 2. Through microscopic analysis of the stomach from swimming stressed rats significant ulceration was observed, confirming that the stress situation was really present. 3. Sensitivity to norepinephrine either in the presence or in the absence of cocaine and propranolol in acutely swimming stressed rats was not altered significantly. 4. Bilateral adrenalectomy was performed in rats 2 days before swimming and acute stress resulted in a supersensitivity to norepinephrine, indicating that adrenal glands may, at least, partially mediate the sensitivity to this drug in vasa deferentia isolated from these animals.


Effects of morphine on isolated right atria of the rat.

1. The present study describes the effects of morphine in the absence or presence of naloxone or atropine in the isolated right atria of the rat. 2. Morphine significantly decreased the auricular chronotropism. 3. The maximal effect was 10 +/- 1.0%. 4. Similar results were obtained in reserpinized animals (13 +/- 0.2% maximum). 5. Naloxone (5 x 10(-7) or 5 x 10(-6) M) did not change the inhibitory effects induced by morphine. 6. The maximal effect obtained with morphine in the presence of atropine (5 x 10(-7) M) was 9 +/- 0.1% similar to that obtained with morphine alone. 7. These results suggest that opioid or vagal mechanisms may not be involved in the cardiac inhibitory effects induced by morphine.


Effect of urethane on hydralazine-induced tachycardia in rats.

1. In conscious normotensive rats, hydralazine (5-10 mg kg-1 p.o.) produced a dose-related fall in systolic blood pressure, accompanied by a pronounced increase in heart rate. 2. The tachycardia induced by hydralazine (10 mg kg-1 p.o.) in conscious normotensive rats was strongly inhibited after anaesthesia with urethane (1.26 g kg-1 i.p.). 3. In anaesthetized normotensive rats, hydralazine (1 mg kg-1 i.v.) caused a fall in mean blood pressure, accompanied by irregular effects on the heart rate that consisted in a combination of initial tachycardia followed by bradycardia. 4. In pithed rats, hydralazine (1 mg kg-1 i.v.) did not affect mean arterial blood pressure but produced a significant decrease in heart rate. 5. In rat isolated atria, hydralazine (2 mM) produced a positive inotropic/negative chronotropic effect. 6. These results suggest that urethane inhibits the cardiovascular reflex that causes the tachycardia induced by hydralazine in conscious normotensive rats. For this reason, in anaesthetized normotensive rats appear the direct effect of the drug on the heart.


Superoxide dismutase and allopurinol prevent the pressor effects of angiotensin II and histamine in the guinea-pig isolated perfused lung exposed to hypoxia.

1. In the guinea-pig isolated perfused lung exposed to hypoxia by infusing N2-gassed Krebs solution, angiotensin II and histamine produced a reduced vasoconstrictor response when compared with the responses obtained in nonhypoxic lung. 2. These reduced vasoconstrictor responses were prevented by prior addition of superoxide dismutase or allopurinol to the medium. 3. These results were taken as evidence for the initiation of the cascade free radical formation in the guinea-pig lung during hypoxia and the primary role of the released intracellular xanthine oxidase. 4. Possible mechanisms of the reduced responses to angiotensin II and histamine and tissue protective activities of allopurinol and superoxide dismutase are discussed.


Vasoconstrictive effects of angiotensin I and II in cat femoral arteries. Role of endothelium.

1. AI and AII induced concentration-dependent contractions in cat femoral artery segments, the potency of AII being greater than that of AI. 2. The antagonist of AII receptors, saralasin (1 and 10 nM), inhibited the AI and AII responses. 3. Indomethacin (10 microM) and endothelium removal increased the responses to AII, whereas those induced by AI were barely affected. 4. The response induced by AI was reduced by captopril (200 microM). 5. These data suggest: (1) the contractions induced by AII are mediated by AII receptors and endothelial products derived from cyclooxygenase, (2) the response to AI is, in part, produced by its conversion into AII.


Ammonium ion increases the tone of rat portal vein.

1. The effect of ammonium ion on vascular tone was investigated using the portal vein isolated from rat. 2. Ammonium chloride at 10-90 mM induced a contractile response. 3. Spontaneous twitch contraction of portal strips was augmented by ammonium chloride at 10-60 mM. 4. Ammonium chloride-induced contraction was abolished in calcium-free solution or in the presence of 1 microM nifedipine. 5. Methylamine (60 mM) also induced a contractile response and augmented the spontaneous twitch contraction in rat portal vein. 6. After withdrawal of ammonium chloride or methylamine from the organ bath solution, the spontaneous twitch contraction was strongly inhibited. 7. These results suggest that ammonium compounds increase vascular tone by causing influx of extracellular calcium through the voltage-dependent calcium channel and intracellular alkalinization is involved in this process.


Studies on the possible role of pharmacokinetics in the development of tolerance to morphine in the rat.

1. The possible role of pharmacokinetics of morphine in the development of tolerance to the analgesic and hyperthermic effects of morphine was studied in the rat. 2. Male Sprague-Dawley rats were made tolerant to morphine by implanting 6 morphine pellets each containing 75 mg of morphine base for 7 days. The assessment of the degree of tolerance to morphine and pharmacokinetic parameters were done 72 hr after pellet removal. 3. Tolerance developed to both the analgesic and hyperthermic effects of morphine as evidenced by decreased responses to morphine in morphine pellet implanted rats compared with placebo pellet implanted rats. 4. The pharmacokinetic parameters, AUC0-->infinity, Cmax, t1/2, k, MRT, Vss and Clt were determined after injecting 5 and 10 mg/kg doses of morphine intravenously to placebo and morphine pellet implanted rats and using a highly sensitive and specific RIA method to quantitate serum levels of morphine. For a 5 mg/kg dose of morphine, the AUC0-->infinity and t1/2 in morphine pellet implanted rats were significantly higher than in placebo pellet implanted rats, but the k value was lower. The other pharmacokinetic parameters for morphine in the two treatment groups did not differ. For 10 mg/kg dose, the only change was an increase in the MRT in morphine tolerant rats when compared to nontolerant rats. 5. The results establish that the development of tolerance to the analgesic and hyperthermic effects of morphine is not related to pharmacokinetics of morphine in serum but may be related to modification of receptor systems in the central nervous system.


Evaluation of the actions of general anaesthetics in the human brain.

1. General anaesthesia is a state of analgesia and impaired cognitive function that results from the depressant effects of anaesthetics. 2. Graded increases in anaesthetic concentration cause a progressive impairment of cognitive function, the extremes of which are commonly described as "light" and "deep" anaesthesia. 3. Surgical stimulation produces activation in the EEG and may arouse a patient from a deeper to a lighter state of cognitive function. 4. It may be very difficult, particularly in patients with neuromuscular blockade, to identify a change in state which results in conscious awareness. 5. A range of methods has been used for evaluating depth of anaesthesia. 6. The evidence reviewed in this paper suggests that the median frequency in the EEG and the auditory evoked potential appear to be the best techniques for monitoring the graded effects of anaesthetics on the brain. 7. The median frequency, which is 10 Hz in conscious subjects, should be kept below 5 Hz during anaesthesia to ensure that there is no response to verbal command. 8. The auditory evoked potential measures the resulting effects of anaesthetic depression and surgical stimulation which is "depth of anaesthesia". 9. However it is not yet certain whether a particular feature e.g. Nb latency, or a collection of features between 20 and 80 msec gives the most reliable index of conscious awareness.


Spinal cord effects of drugs used in anaesthesia.

1. Measurement of nociceptive thresholds at two skin sites in rats with chronic intrathecal catheters has allowed study of drug actions demonstrated to be at spinal level. 2. Using this preparation we have demonstrated segmental antinociceptive effects following intrathecal administration of agonists selective for benzodiazepine receptors, mu, kappa and delta opioid receptors, 5-hydroxytryptamine (5-HT) receptors and alpha adrenoceptors. 3. Such effects were dose related and were suppressed by appropriate selective antagonists. 4. Antagonist dose-response curves have been constructed for suppression of antinociceptive effects of various agonists. This has revealed complex interactions between spinal systems; for example midazolam produces its actions by activating an opioid system involving delta receptors.


Cellular and synaptic actions of general anaesthetics.

1. This paper briefly reviews mechanisms by which such widely-used volatile anaesthetics as halothane and isoflurane suppress neural function in the brain. 2. In general, anaesthetics tend to depress neuronal firing and excitatory synaptic transmission, and potentiate synaptic inhibition. 3. According to recent evidence, a particular important action of anaesthetics is to inactivate a variety of both voltage-dependent and agonist-triggered Ca-currents. 4. Activation of K outward currents and Na inward currents probably occurs only with higher doses of anaesthetics. 5. How anaesthetics interfere with Ca-channels remains largely a matter of speculation--though some evidence favours a Ca-mediated action, following Ca2+ release from internal stores, that may account also for potentiation of IPSPs by prolonging the opening of GABA-activated Cl- channels. 6. Whatever its precise underlying mechanism, a suppression of Ca-influx into pre-synaptic terminals could well account for the depression of excitatory synaptic transmission.


The action of anaesthetics on stimulus-secretion coupling and synaptic activity.

1. Anaesthetics are known to depress excitatory synaptic transmission and the mechanism of this inhibition has been investigated using bovine adrenal chromaffin cells as an experimental model. 2. These cells are homologous with post-ganglionic sympathetic neurons and have well characterized receptor and secretory mechanisms. They are amenable both to the direct measurement of evoked secretion with its associated ion fluxes, and to electrophysiological investigation using the patch clamp technique. 3. These approaches have been used to study the influence of anaesthetics on pre- and post-synaptic mechanisms involved in stimulus-secretion coupling. 4. A variety of agents inhibited secretion evoked by direct depolarization, and this was shown to be due to a reduction in calcium influx. 5. Direct inhibition of voltage-gated calcium currents was confirmed by whole-cell patch clamp measurements. 6. In addition, anaesthetics powerfully modulated nicotinic receptor mediated events: carbachol-evoked secretion was more sensitive to anaesthetics than that stimulated by high potassium. 7. The mechanism of anaesthetic action on the nAChR was examined in more detail with patch-clamp experiments. 8. These showed that anaesthetics reduced the probability of channels being in the open state, largely as a result of reduction in mean channel open time. 9. The data are discussed in relation to excitatory synaptic transmission.


Differential effects of general anaesthetics on identified molluscan neurones in situ and in culture.

1. The only unifying principle of general anaesthesia is that general anaesthetics interact with membrane components and no single cellular mechanism appears to explain their widespread effects in the central nervous system. 2. The gastropod mollusc, Lymnaea stagnalis, provides an excellent model system for studies on general anaesthetics because it has large, uniquely identifiable nerve cells. Several of these cells are interneurones with identified neurotransmitters and monosynaptic connections to other cells. 3. Recent work on Lymnaea neurones suggests that calcium currents are depressed by volatile general anaesthetics applied in the clinical range, whilst evidence from other preparations indicates that there is a rise in intracellular calcium concentration following application of these substances. 4. Identified Lymnaea neurones have different responses to applied anaesthetics, irrespective of the anaesthetic used. Following application of halothane, barbiturates and several other anaesthetic agents, some cells gradually become quiescent after a short period, whilst in others a series of paroxysmal depolarizing shifts occur prior to quiescence. 5. Cultured neurones of Lymnaea, Helisoma and related species retain their characteristic action potential types and neurotransmitter identity. Their responses to anaesthetics are similar to those in the intact brain. They may also form synapses in culture. Thus, they are a useful tool for studying the cellular and subcellular actions of general anaesthetics.


The action of anaesthetics and high pressure on neuronal discharge patterns.

1. The membrane actions of both anaesthetics and high pressure have been studied in rat hippocampal slices in experiments where either field potential (orthodromic or antidromic) responses from the CA1 region are recorded or intracellular measurements in CA1 neurones are made. 2. It is clear that anaesthetics have multiple post-synaptic actions in CA1 pyramidal neurones. For example, the amplitude of antidromic field potential responses are depressed (e.g. 2.5% enflurane) or increased (20 mM ketamine) or recruitment of a second population spike occurs (2.5% halothane). 3. In separate intracellular experiments anaesthetics have been shown to hyperpolarize [e.g. inhalations (2.5%), or methohexitone, 50-100 microM), or depolarize (ketamine, > or = 20 microM), CA1 pyramidal neurones decreasing or increasing respectively the responses to weak depolarizing synaptic input, or direct stimulation. 4. In the case of some anaesthetics (inhalation agents or ketamine), the accommodation of action potential discharge is also decreased, this being accompanied by a reduction in the amplitude of the associated slow after hyperpolarization (AHP). Consequently many neurones fire repetitively in response to long lasting, strong depolarizing inputs. Sub-classes of K+ channel such as the M (channel closed by muscarinic agonists) and the SK (Ca(2+)-dependent K+ channel of small conductance) type are currently believed to control the accommodation of spike discharge and the AHP. Consistent with this idea is the finding that in voltage-clamp experiments enflurane decreased reversibly the M current. 5. Methohexitone (50 microM) does not block the accommodation of action potential discharge but interestingly induces a long lasting depolarization and action potential bursting. 6. In comparison, high pressure (51-101 ATA) can induce a second population spike in antidromic field potential recordings, indicative also of a post-synaptic action. 7. There is no apparent change in the resting membrane potential or input resistance of CA1 neurones at high pressure, however 51 or 101 ATA produced a reduction in the accommodation of action potential discharge and the associated AHP leading to repetitive discharge in response to strong (0.7 nA) depolarizing currents. 8. In a few neurones spontaneous depolarizations and action potential discharge also occurred during compression between 51-101 ATA. 9. Our working hypothesis is that certain subclasses of neuronal K+ channel represent interesting targets for both anaesthetic and high pressure action.


Molecular basis of a unique African variant (A-IV 5) of human apolipoprotein A-IV and its significance in lipid metabolism.

Human apolipoprotein A-IV (apoA-IV) exhibits a genetically determined structural polymorphism amenable to analysis by isoelectric focusing and immunoblotting techniques. We have determined the allele frequency and molecular basis of a unique ApoA-IV*5 allele which is widely distributed among blacks but is absent in other populations. The frequency of the ApoA-IV*5 allele in blacks (N = 308) was estimated to be 3.2%. In comparison to the common ApoA-IV*1 allele, analysis of coding and non-coding sequences of the ApoA-IV*5 allele revealed an in-frame insertion of 12 nucleotides near the carboxyl terminal region of the mature protein. The insertion involves an exact duplication of the second of the four repeats and codes for 4 amino acids glutamic acid (GAA), glutamine (CAG), glutamine (CAG), and glutamine (CAG) and is responsible for the charge shift of the the apoA-IV 5 isoform slightly toward the anode as compared to the wild type apoA-IV 1 isoform on the isoelectric focusing gel. This in-frame insertion occurs in a region which is highly conserved among rat, mouse, and humans. In addition to the 12 nucleotide insertion, the four individuals sequenced for the ApoA-IV*5 allele also revealed a same-sense mutation by replacing G to T at the third position of codon 316. Our preliminary data suggest that this unique black allele marker may be of potentially significance in studies of human lipid metabolism and in microevolution.


Segregation analysis of height-adjusted weight with generation- and age-dependent effects: the Nancy Family Study.

A segregation analysis using a regressive model with generation- and age-dependent effects was applied to familial data of height-adjusted weight to investigate the major gene hypothesis. The sample included 629 nuclear families with 2,534 members volunteering for a free health check-up in the Preventive Medicine Center of Vandoeuvre-lès-Nancy, France. The familial correlations were 0.094 +/- 0.040 between spouses, 0.198 +/- 0.023 between parent and offspring, and 0.327 +/- 0.034 between siblings. The variability of the trait was higher in parents than in offspring. The most parsimonious genetic model indicated a codominant major effect increasing with age in childhood, then stabilizing in adulthood. The same data were analyzed using the classical mixed model, assuming equality of variances between parents and offspring, no resemblance between spouses, similar parent-offspring and sib-sib correlations, and identical effects in parents and offspring. This analysis indicated a recessive solution. In both analyses, mendelian transmission was rejected. However, the mixture of two distributions in the recessive model, instead of three in the codominant one, was less constraining with respect to the test of transmission probabilities, and the rejection of mendelian transmission was due to a single family in the recessive case, instead of several families in the codominant one. This could possibly explain why previous studies, all using the mixed model, found evidence for a recessive major gene. Although the major gene hypothesis cannot be definitely ruled out from our results, the mechanism appears more complex than the effect of one single gene.


Longitudinal study of the association between ABO phenotype and total serum cholesterol level in a Japanese cohort.

The relationship between ABO blood phenotype and total serum cholesterol (TC) level was examined in a Japanese population to determine whether an elevated TC level is associated with phenotype A, as has been demonstrated in many West European populations. Such studies in nonwhite populations are scarce, and findings generally failed to demonstrate the relationship. Inconsistent results from cross-sectional studies of various racial groups with widely varying ages raised an age effect as a possible explanatory factor. It was also suggested that the ABO-TC association may not be apparent in populations with low fat intake or low mean cholesterol level. These hypotheses are addressed by examining long-term TC data collected serially from the unexposed controls of the atomic bomb survivors in Hiroshima and Nagasaki who were participants of the Adult Health Study program at the Atomic Bomb Casualty Commission-Radiation Effects Research Foundation between 1958 and 1986. The statistical method of growth curve analysis, through the mixed effect model of Laird and Ware [1982], was used to model age-dependent changes in cholesterol levels within individuals. The effects of the ABO polymorphism in modifying the resultant growth curve are examined. We demonstrate that TC levels are elevated on average by about 4 mg/dl in phenotype A compared to non-A in the Japanese (P < 0.00001), and that this relationship is maintained from early to late adulthood, independent of sex, body mass index, cohort status, or city of residence. Thus, phenotype A individuals may be more predisposed to cardiovascular disease through one of its major risk factors. This is the first study of the ABO-cholesterol association in the Japanese, and the first based on a cohort with longitudinally collected TC data.


Numerical comparisons of two formulations of the logistic regressive models with the mixed model in segregation analysis of discrete traits.

Segregation analysis of discrete traits can be conducted by the classical mixed model and the recently introduced regressive models. The mixed model assumes an underlying liability to the disease, to which a major gene, a multifactorial component, and random environment contribute independently. Affected persons have a liability exceeding a threshold. The regressive logistic models assume that the logarithm of the odds of being affected is a linear function of major genotype effects, the phenotypes of older relatives, and other covariates. A formulation of the regressive models, based on an underlying liability model, has been recently proposed. The regression coefficients on antecedents are expressed in terms of the relevant familial correlations and a one-to-one correspondence with the parameters of the mixed model can thus be established. Computer simulations are conducted to evaluate the fit of the two formulations of the regressive models to the mixed model on nuclear families. The two forms of the class D regressive model provide a good fit to a generated mixed model, in terms of both hypothesis testing and parameter estimation. The simpler class A regressive model, which assumes that the outcomes of children depend solely on the outcomes of parents, is not robust against a sib-sib correlation exceeding that specified by the model, emphasizing testing class A against class D. The studies reported here show that if the true state of nature is that described by the mixed model, then a regressive model will do just as well. Moreover, the regressive models, allowing for more patterns of family dependence, provide a flexible framework to understand gene-environment interactions in complex diseases.


Large-scale methylation patterns in the nuclear genomes of plants.

Methylation was investigated in compositional fractions of nuclear DNA preparations (50-100 kb in size) from five plants (onion, maize, rye, pea and tobacco), and was found to increase from GC-poor to GC-rich fractions. This methylation gradient showed different patterns in different plants and appears, therefore, to represent a novel, characteristic genome feature which concerns the noncoding, intergenic sequences that make up the bulk of the plant genomes investigated and mainly consist of repetitive sequences. The structural and functional implications of these results are discussed.


Structure of the gene encoding potato cytosolic pyruvate kinase.

The polymerase chain reaction (PCR) has been used to generate a series of overlapping genomic clones representing 43 bp of 5' untranslated sequence, 63 bp of 3' untranslated sequence and the entire coding sequence of the gene encoding potato cytosolic pyruvate kinase (PKc). This portion of the gene is approximately 4.5 kb in length and is interrupted by three introns, one of which is present in the 5' untranslated region. Southern blot analysis indicates that PKc is encoded by a small gene family, and sequence data from a number of PCR-derived genomic clones indicate that there are as many as six PKc genes. Sequence differences between the PCR-generated genomic clones and a PKc cDNA clone are discussed with respect to the fidelity of Taq polymerase. An alignment of intron placement in the potato PKc gene with intron placement in PK genes from other sources indicates that two of the potato introns correspond to intron positions in other species.


High-level production of active HIV-1 protease in Escherichia coli.

High levels of active HIV-1 protease (PR) were produced in Escherichia coli, amounting to 8-10% of total cell protein. High production levels were achieved by altering the following parameters: (1) codon preference of the coding region, (2) A+T-richness at the 5' end of the coding region, and (3) promoter. To circumvent the toxicity of HIV-1 PR in E. coli, the gene was expressed as a fusion protein with two different proteolytic autocleavage sequences. In both the cases, the fusion protein could be cleaved in vivo to give an active molecule with the native sequence at the N terminus.


A position- and orientation-dependent element in the first intron is required for expression of the mouse hprt gene in embryonic stem cells.

The gene (hprt) coding for mouse HPRT (hypoxanthine phosphoribosyltransferase) is transcribed from a promoter lacking CAAT and TATAA boxes. It is expressed ubiquitously, albeit at different levels, in all tissues and cultured cells. During investigations to characterise hprt transcription control elements required in embryonic stem (ES) cells and to develop compact hprt minigenes for gene-targeting strategies, we discovered a requirement for intron-1 sequences for expression in ES cells. The essential intron-1 element, which is 420 bp long, is located 230 bp downstream from the transcription start point and is shown to increase transcription from the hprt promoter in a position- and orientation-dependent manner. We propose that this element is an integral downstream part of the hprt promoter.


Membrane mu poly(A) signal and 3' flanking sequences function as a transcription terminator for immunoglobulin-encoding genes.

Developmentally regulated mechanisms involving alternative RNA splicing and/or polyadenylation, as well as transcription termination, are implicated in controlling the levels of secreted mu (mu s), membrane mu (mu m) and delta immunoglobulin (Ig) heavy chain mRNAs during B cell differentiation (mu gene encodes the mu heavy chain). Using expression vectors constructed with genomic DNA segments composed of the mu m polyadenylation signal region, we analyzed poly(A) site utilization and termination of transcription in stably transfected myeloma cells and in murine fibroblast L cells. We found that the gene segment containing the mu m poly(A) signals, along with 536 bp of downstream flanking sequence, acted as a transcription terminator in both myeloma cells and L cell fibroblasts. Neither a 141-bp DNA fragment (which directed efficient polyadenylation at the mu m site), nor the 536-bp flanking nucleotide sequence alone, were sufficient to obtain a similar regulation. This shows that the mu m poly(A) region plays a central role in controlling developmentally regulated transcription termination by blocking downstream delta gene expression. Because this gene segment exhibited the same RNA processing and termination activities in fibroblasts, it appears that these processes are not tissue-specific.


The cDNA sequence, expression pattern and protein characteristics of mouse protein kinase C-zeta.

A 2199-bp complementary DNA (cDNA) that encodes protein kinase C-zeta (PKC-zeta) has been isolated from mouse brain by a combination of reverse transcription and primer extension. The predicted PKC-zeta protein consists of 592 amino acids which are 99% identical to those of rat PKC-zeta. Northern blots that were probed with this cDNA revealed abundant 2200-nucleotide (nt) and 4200-nt PKC-zeta mRNAs in mouse brain in roughly equal amounts. PKC-zeta mRNA was also abundant in normal lung, kidney, and testes, and in several hemopoietic tumor lines. In all other mouse tissues and cell lines that were examined, at least faint levels of PKC-zeta mRNAs could also be detected. In tissues other than brain, the amount of PKC-zeta mRNA was less, and the smaller species generally predominated. Furthermore, in these tissues, both PKC-zeta mRNAs appear to be approximately 200 nt longer than the two mRNAs found in the brain. When the cDNA is expressed in insect cells via a baculovirus expression vector, a 75-kDa protein is synthesized which, unlike other PKC isoforms, does not bind phorbol ester, even at very high concentrations.


A novel procedure for quantitative polymerase chain reaction by coamplification of competitive templates.

A method is described for the absolute quantification by polymerase chain reaction (PCR) of nucleic acids present in low abundance. The method entails the addition to the sample of competitor DNA molecules that share the same sequence as the amplified target (including primer recognition sites), except for a 20-bp insertion in the middle, which allows easy resolution by gel electrophoresis (competitive PCR). Among the advantages of competitive PCR is that any predictable or unpredictable variable that affects amplification has the same effect on both target and competitor species and that the final ratio of amplified products reflects exactly the initial rate of targets, rendering the reaction independent of the number of amplification cycles. An easy and reliable method for the construction and quantification of competitive templates obtained as recombinant PCR products was developed. The technique was used for the absolute quantification of human genomic DNA with primers from a single copy, subtelomeric region of chromosome 19.


Compositional mapping of the human dystrophin-encoding gene.

The genomes of warm-blooded vertebrates are mosaics of long DNA segments (> 300 kb, on the average), the isochores, homogeneous in GC levels, which belong to a small number of compositional families. In the present work, the human dystrophin-encoding gene, spanning more than 2.3 Mb in Giemsa band Xp21 (on the short arm of the X chromosome), was analyzed in its isochore organization by hybridizing cDNA probes, corresponding to eight contiguous segments of the coding sequence, on compositional fractions from human DNA. Five DNA regions of uniform (+/- 0.5%) GC content, separated by compositional discontinuities of about 2% GC, were found, so providing the first high-resolution compositional map obtained for a human genome locus and the first direct estimate of isochore size (360 kb to more than 770 kb, in the locus under consideration). One of the isochores contains 71% and another one 21% of deletion breakpoints found in patients suffering from Duchenne's and Becker's muscular dystrophies.


Identification of two silencers flanking an AP-1 enhancer in the vimentin promoter.

We have studied the 5' upstream sequences required for the transcriptional regulation of the hamster gene encoding the intermediate filament protein, vimentin. Although vimentin is regarded as the intermediate filament protein of mesothelial tissue, it is also produced in most cultured cells. The human mammary carcinoma cell line, MCF-7, belongs to the exceptions. It contains no vimentin, and the complete upstream promoter region is inactive in this particular cell line. By using transient transfection of chimeric constructs into MCF-7 and HeLa cells, and subsequent chloramphenicol acetyltransferase assays, we were able to show the presence of two negative control regions flanking a double AP-1 enhancer element. Our data indicate that these elements exert their effect irrespective of orientation and position, suggesting that they are silencers. In vitro footprinting assays, gel mobility assays and Southwestern (protein-DNA) blotting revealed the presence of trans-acting factors interacting with both silencer elements. The silencing effect was particularly pronounced in MCF-7 cells, although DNA-binding proteins are present in HeLa cells as well.


Sequence and in vitro translational analysis of a 1629-nucleotide ORF in Autographa californica nuclear polyhedrosis virus strain E2.

The complete nucleotide (nt) sequence of an open reading frame (ORF) (map unit 5.1 to 3.8) from Autographa californica nuclear polyhedrosis virus strain E2 (AcMNPV-E2) has been determined. This 1629-nt ORF has a coding potential for a 61-kDa Pro-rich protein. However, in vitro translation of the 1629-nt ORF and sodium dodecyl sulfate-polyacrylamide-gel electrophoresis (SDS-PAGE) revealed a 78-kDa protein product. The discrepancy between the M(r) predicted by the nt sequence and that obtained from the in vitro translational analysis is due to the high Pro content of this protein. The high Pro content causes anomalous migration of this protein during SDS-PAGE.


Production and secretion of a bifunctional staphylococcal protein A::antiphytochrome single-chain Fv fusion protein in Escherichia coli.

A bifunctional molecule was genetically engineered which contained the secretory signal and four Fc-binding domains of Staphylococcus aureus protein A (FcA), fused to a single-chain Fv (scFv) derived from an immunoglobulin (Ig) G1 mouse monoclonal antibody (AS32) directed against the plant regulatory photoreceptor protein, phytochrome. The FcA::AS32scFv sequence was encoded in a single synthetic gene and expressed as a 60-kDa periplasmic protein in Escherichia coli. The bifunctionality of the fusion protein was established by its ability to bind to both IgG-agarose and phytochrome-sepharose. Growth of cultures, producing the FcA::AS32scFv, at 37 degrees C, resulted in a decrease in the periplasmic accumulation of the fusion protein, and an increased accumulation of an assumed degradation product which retained Fc-binding activity. Growth of cultures at lower temperatures favoured the accumulation of undegraded fusion protein. The recombinant fusion protein could be purified to homogeneity by a simple, rapid chromatography procedure.


Mouse microtubule-associated protein 4 (MAP4) transcript diversity generated by alternative polyadenylation.

Mouse microtubule-associated protein 4 (MAP4) is a protein that co-locates with microtubules in vivo. It is encoded by a single-copy gene that expresses multiple transcripts in most cell types [West et al., J. Biol. Chem. 266 (1991) 21886-21896]. This report describes the identification of two distinct 3'-untranslated regions (UTR) for MAP4 transcripts. The 3'-UTRs of the transcripts are identical up to the site of polyadenylation of the shorter mRNA. The longer transcript contains an additional 775 nucleotides after the first polyadenylation site. Both poly(A) tails follow the canonical polyadenylation site motif, AAUAAA. These data show that two different UTRs arise as a result of alternative polyadenylation site usage. Northern blots of RNA from different tissues probed with coding sequence show hybridization to the common 5.5- and 6.5-kb transcripts, whereas blots probed with sequence unique to the longer 3'-UTR show hybridization only to the 6.5-kb band. Both transcripts are found within the same cell type. In addition, muscle contains additional transcripts of 8 and 9 kb, of which only the 9-kb transcript hybridizes to the longer 3'-UTR probe.


Production of methionyl-minus ovine growth hormone in Escherichia coli and one-step purification.

The overproduction of ovine growth hormone (oGH) in Escherichia coli is described, achieved in part by alteration of the codon usage for nine of the first 15 amino acids (aa) of the mature hormone. Recombinant oGH (re-oGH), representing 12% of the total cellular protein, was isolated from inclusion bodies by solubilisation using the cationic surfactant cetyltrimethylammonium chloride (CTAC). The hormone was refolded and subsequently purified to greater than 95% homogeneity in a single step using preparative reverse phase high performance liquid chromatography. The aa sequence analysis revealed that the N-terminus of the E. coli-derived polypeptide was identical to that of pituitary-derived oGH, and re-oGH displayed potent somatotropic activity in vivo.


A pseudogene for human glutathione peroxidase.

Glutathione peroxidases (GPx) serve a bioprotective function in the reduction of peroxides to less toxic substances. Both cellular and secreted forms of the protein have been reported, as well a number of distinct cDNA sequences. Previous efforts have described three distinct loci on human chromosomes 3, 21 and X which hybridize to a GPX cDNA and these authors have speculated that only the chromosome 3 locus encodes a functional GPX gene. This conclusion was based on mapping studies showing a precise deletion of intron sequences in the GPX loci on chromosomes 21 and X despite strong conservation among these sequences in both the coding and 3'-untranslated regions. To pursue this issue, we have isolated the chromosome 21 GPX locus by molecular cloning and determined its nucleotide sequence. Consistent with the expectations of McBride et al. [Biofactors 4 (1988) 285-292], the sequence does reveal a highly conserved processed pseudogene. It is suggested that a retrotransposed copy of the GPX gene integrated into chromosome 21 and may have maintained activity prior to the accumulation of inactivating mutations.


Cloning of a cDNA encoding the Tcp-1 (t complex polypeptide 1) homologue of Arabidopsis thaliana.

We isolated a plant homologue of Tcp-1 (t complex polypeptide 1) cDNA from Arabidopsis thaliana. It encodes a 545-amino acid (aa) protein, which has extensive aa and nucleotide sequence homology to the corresponding proteins of mouse, yeast, fruit fly and archaebacteria.


Analysis of a cDNA from the neurologically active locus shaking-B (Passover) of Drosophila melanogaster.

We have isolated and sequenced a cDNA from the shaking-B locus of Drosophila melanogaster. The cDNA contains an open reading frame with extensive homology to another D. melanogaster gene, l(1)ogre. This suggests the existence of a new family of proteins required for the development and maintenance of the D. melanogaster nervous system.


Characterization of the gene encoding human pituitary-specific transcription factor, Pit-1.

Pit-1 is a pituitary-specific transcription factor that binds to and transactivates promoters of growth hormone- and prolactin-encoding genes. A chromosomal gene related to human Pit-1 isolated from human gene libraries was over 14 kb long and split into six exons. All of the splice donor and acceptor sites conformed to the GT/AG rule. The gene was mapped to human chromosome region 3p11.


Oesophageal motor function before and after healing of oesophagitis.

Forty three patients with reflux oesophagitis were studied to investigate the effect of healing on oesophageal function. All patients underwent oesophageal manometry and transit studies before and after complete healing of oesophagitis. Oesophagitis was treated with omeprazole 40 mg/day for a median duration of 12 weeks. Twenty three patients also had an acid clearance test before and after healing. Thirty eight of the 43 patients had 24 hour oesophageal pH monitoring before treatment and this was repeated after healing (while on omeprazole) in 31 of them. Thirty four volunteers served as controls. All volunteers underwent manometry, 33 had oesophageal transit studies, and 23 had acid clearance test. Patients had significantly reduced lower oesophageal sphincter pressures and distal and middle oesophageal amplitudes, longer durations of contraction, and slower velocity of propagation than the controls (16.5 v 22.5 mm Hg; 52 v 92 mm Hg; 46 v 79 mm Hg; 3.1 v 2.7 seconds; and 3.3 v 4.1 cm/second respectively with the corresponding p values = 0.017; 0.0001; 0.0001; 0.017; and 0.006). Patients had significantly longer transit times (9 v 7 and 17 v 11 seconds: p = 0.027 and 0.002 for erect and supine postures respectively). They also had longer acid clearance times (350 v 288 and 536 v 405 seconds: p = 0.044 and 0.016 for sitting and supine postures respectively). There was no significant change in any of the indices of oesophageal function after healing of oesophagitis (lower oesophageal sphincter pressure = 16.5 v 20; distal amplitude = 52 v 60; middle amplitude = 46 v 49; duration of contraction = 3.1 v 3.1; velocity = 3.3 v 3.3; erect transit time = 9 v 9; supine transit time = 17 v 24; acid clearance test (sitting) = 350 v 371; acid clearance test (supine) = 536 v 645). These results indicate that oesophageal motor dysfunction in reflux oesophagitis is a primary phenomenon.


Helicobacter pylori: a risk and severity factor of non-steroidal anti-inflammatory drug induced gastropathy.

This prospective study aimed to determine the prevalence of Helicobacter pylori infection in relation to the occurrence and severity of NSAIDs induced gastropathy. A total of 111 patients were studied-66 were taking NSAIDs and 45 were control patients. All patients underwent endoscopy during which antral biopsy specimens were taken to determine H pylori status (Gram and Giemsa staining, urease test, and cultures). The NSAID group comprised: group I, patients without mucosal damage (n = 28); group II, patients with gastropathy (n = 26); and group III, patients with bleeding associated with NSAID induced gastropathy (n = 12). Control patients had neither dyspeptic symptoms nor endoscopic lesions. There were no differences in age, sex ratio, or presence of H pylori (26% v 24%) between the NSAID and the control groups. Among patients taking NSAIDs, H pylori infection was more frequently (p < 0.02) diagnosed in those who presented with gastropathy (groups II and III: 37%) than in those without lesions (group I: 11%). The frequency of H pylori infection increased significantly with the severity of gastropathy (group I = 11%; group II = 31%; group III = 50%; p < 0.03). H pylori infection was associated with chronic active gastritis (group I = 21%; group II = 35%; group III = 67%; p < 0.05). These data suggest that H pylori may be a risk factor of NSAID induced gastropathy.


Role of ammonia in the pathogenesis of the gastritis, hypergastrinaemia, and hyperpepsinogenaemia I caused by Helicobacter pylori infection.

Studies were performed in patients with and without renal failure to investigate the role of bacterial ammonia production in the pathogenesis of the mucosal abnormalities caused by Helicobacter pylori. The high rate of H pylori ammonia production in uraemic patients should accentuate any ammonia induced effects. The median (range) gastric juice ammonium concentration in the H pylori positive patients with renal failure was 19 mmol/l (II-43) compared with 5 mmol/l (1-11) in the H pylori positive patients without renal failure (p < 0.005). In the H pylori negative patients the values were 3 mmol/l (0.5-11) and 0.7 mmol/l (0.1-1.4) respectively in the patients with and without renal failure (p < 0.01). Despite the much higher ammonia production in the H pylori positive uraemic patients, the nature and severity of their gastritis was the same as that in the H pylori positive non-uraemic patients. The median (range) fasting serum gastrin concentration was raised in the uraemic patients compared with the non-uraemic patients but was similar in the uraemic patients with (95 pmol/l (52-333)) or without (114 pmol/l (47-533)) H pylori infection. The median (range) serum pepsinogen I concentration was also high in the uraemic compared with the non-uraemic patients and was significantly higher in uraemic patients with H pylori (352 ng/ml, range 280-653) than in those without H pylori infection (165 ng/ml, range 86-337) (p < 0.01). These findings indicate that the gastritis and hypergastrinaemia associated with H pylori infection are not the result of mucosal damage induced by the organism's ammonia production.


Concentrations of metals in gastric juice in health and peptic ulcer disease.

The concentrations of essential metal cations in gastric juice, collected at endoscopy from 17 normal patients and 11 with peptic ulcer disease, were determined by inductively coupled plasma emission spectrometry. Mean fasting levels in normal gastric juice were as follows: sodium 47.7 mM, potassium 14.6 mM, calcium 0.8 mM, magnesium 0.36 mM, zinc 13 microM, and copper 1.2 microM: these did not differ significantly in health or disease. Because samples were contaminated with iron, the concentration of this metal was only estimated (ca 3.5 microM in normal subjects), and this secretion could represent a significant proportion of the daily loss of endogenous iron. The pH of gastric juice predicted the concentrations of magnesium and calcium, but not copper or zinc, in the juice. It is concluded that previously reported values for trace metals in gastric juice have been incorrect and that the very low amounts secreted in the gastric juice will not interfere with the absorption of other trace metals from the diet. In contrast, the concentrations of macroelements in gastric juice may be sufficient to stimulate the absorption of trace metals from the gut.


Low grade B cell mucosa associated lymphoid tissue lymphoma of the stomach: clinical and endoscopic features, treatment, and outcome.

A retrospective study of the clinical and endoscopic features of low grade gastric lymphomas of mucosa associated lymphoid tissue (MALT) in 16 patients together with treatment and outcome was undertaken. Immunohistochemical studies of fresh tissue easily distinguished MALT lymphoma from benign reactive lymphoid hyperplasia (pseudolymphoma) and showed that tumour cells had the characteristic phenotype indicative of their origin from MALT. Persistent epigastric pain was the main presenting complaint, and was often associated with acute bleeding, anaemia, or weight loss. Eight patients had a past history of recurrent peptic ulcers or gastritis. The endoscopic appearance suggested malignancy in only half the cases and was compatible with gastritis or a benign peptic ulcer in the remainder. There was extragastric involvement of other mucosal sites in eight patients (mainly the lung, but also the parotid gland and small bowel), but rarely was bone marrow and never the spleen or peripheral lymph nodes affected. Conservative treatment with long term cyclophosphamide was effective in both stage I and stage IV disease, and all the patients are alive after a median follow up of 4.5 years. These findings confirm that low grade gastric MALT lymphomas are usually indolent tumours with non-specific endoscopic aspects and show that dissemination to other mucosal sites was more frequent than previously reported. Monochemotherapy could be an effective alternative treatment to surgery.


Endomysial antibody: is it the best screening test for coeliac disease?

The sensitivities and specificities of the IgA and IgG antigliadin antibody and the IgA antireticulin antibody have been compared with the recently described endomysial antibody directed against the basement membrane of smooth muscle in monkey oesophagus. One hundred and seventeen patients with adult coeliac disease (21 untreated), 84 patients with inflammatory bowel disease, systemic lupus erythematosus and rheumatoid arthritis (comprising the disease control group), 47 normal controls and a miscellaneous group of 29 patients, who were selected because of a positive reticulin staining pattern, were investigated. These results were correlated with the degree of abnormality of the intestinal mucosa in patients with adult coeliac disease. Endomysial antibodies were found in all patients with untreated coeliac disease and subtotal villous atrophy and in 47% of patients on a non-strict gluten free diet. One patient on a strict gluten free diet was positive and had partial villous atrophy while all patients in disease control groups were negative. Results were variable with the antireticulin and antigliadin antibodies. Sensitivity and correlation with subtotal villous atrophy in the untreated patients was 100%. It is concluded that the endomysial antibody is superior to other current antibody tests and should be used in preference for the diagnosis of coeliac disease.


Differentiation status of rat enterocytes after intestinal adaptation to jejunoileal bypass.

The differentiation status of epithelial cells in intestinal adaptation remains unclear. To determine whether enterocytes reach optimum maturity following adaptation after 85% shortening of the rat gut by jejunoileal bypass surgery, activities of two brush border enzymatic markers of differentiation, alkaline phosphatase and sucrase, were examined in subpopulations of epithelial cells isolated sequentially from the villus/crypt axis of normal (sham operated) and hyperplastic mucosa. In jejunal villi, adaptational hyperplasia was associated with an increase in total epithelial alkaline phosphatase, but not total sucrase, activity; alkaline phosphatase activity increased most obviously in cells at the 11-50% position (from the tip) on villi. In hyperplastic ileal villi, total alkaline phosphatase activity fell, although sucrase activity did not change significantly. Specific activity (per mg protein) of sucrase on jejunal villus epithelium was reduced by the adaptational changes to bypass; alkaline phosphatase specific activity remained unchanged. In the ileum, despite adaptational changes to bypass, there was no increase in the normally low specific activities of sucrase and alkaline phosphatase. Bypass surgery did not change the major site of expression of either enzyme on jejunal or ileal villi. In conclusion, enzymatic markers of functional differentiation are not all equally affected by adaptational hyperplasia. Hypertrophy of villi and increased cell proliferation seen in jejunum remaining exposed to luminal contents resulted in an increase in the alkaline phosphatase but not the sucrase content. This is not, therefore, the result of a simple immaturity of villus cells. Morphological adaptation in the ileum, however, is not accompanied by adaptation of brush border enzyme markers of differentiation, confirming a functional immaturity of these cells. Strategies for increasing the expression of these markers may have clinical value.


Use of coculture of colonic mucosal biopsies to investigate the release of eicosanoids by inflamed and uninflamed mucosa from patients with inflammatory bowel disease.

Eicosanoid production was measured in cultured biopsies of colonic mucosa from control patients, with the irritable bowel syndrome, and from patients with proctosigmoiditis and with colonic Crohn's disease. Cultured inflamed colonic mucosa from patients with proctosigmoiditis and Crohn's disease produced more prostaglandin E2 and leukotrienes C4 than control tissues. In addition, eicosanoid production by macroscopically uninflamed or 'quiescent' mucosa from the right colon was examined in patients with proctosigmoiditis and between skip lesions in Crohn's disease patients. In the proctosigmoiditis group quiescent mucosa produced eicosanoids in similar quantities to control tissue. Coculture of quiescent plus inflamed tissue however, generated a marked increase in eicosanoid output in 12 of 20 of the patients and this was similar to the quantity obtained from two pieces of inflamed tissue. In the Crohn's disease group, quiescent mucosa produced more eicosanoids than control mucosa but production was markedly stimulated by coculture with inflamed mucosa in all patients. These findings suggest that in some patients with proctosigmoiditis and in all patients with Crohn's disease quiescent mucosa appears to be sensitised. A small but significant increase in the macrophage population may be partly responsible but it is likely that these and other cells are primed to release eicosanoids, and may be induced to do so by soluble mediators produced by actively inflamed tissue.


Water and solute absorption from a new hypotonic oral rehydration solution: evaluation in human and animal perfusion models.

Controversy continues regarding the optimal composition of glucose electrolyte oral rehydration solutions for the treatment of acute diarrhoea. Four perfusion models (normal human jejunum, normal rat small intestine, cholera toxin treated secreting rat small intestine and rotavirus infected rat small intestine) have been developed and used to compare the efficacy of a hypotonic oral rehydration solution with standard United Kingdom British National formulary and developing world oral rehydration solutions (WHO). Despite obvious physiological and pathophysiological differences between these models there was general congruence in the water and solute absorption profiles of the different oral rehydration solutions. Hypotonic oral rehydration solution promoted significantly greater water absorption than other oral rehydration solutions in all rat models (p < 0.001) but apparently increased water absorption failed to achieve significance in human jejunum. British National Formulary-oral rehydration solution was unable to reverse net water secretion in both rotavirus and cholera toxin models. Net sodium absorption from hypotonic and WHO-oral rehydration solutions was significantly greater than from the low sodium British National Formulary-oral rehydration solutions (p < 0.001) except in the rotavirus model when absorption was similar to hypotonic-oral rehydration solutions. These findings show that there is agreement in the apparent efficacy of oral rehydration solutions in these animal and human perfusion models, and that improved water absorption with adequate sodium absorption may be achieved by reducing oral rehydration solution osmolality.


Collagen synthesis in fibroblasts from human colon: regulatory aspects and differences with skin fibroblasts.

The purpose of this study was to examine regulation of collagen synthesis in human colon fibroblasts and compare the results from colon fibroblasts with those obtained in fibroblasts from human skin. The effects of interleukin-1 beta, tumour necrosis factor alpha, interferon gamma, transforming growth factor-beta, dexamethasone, and the calcium ionophore A23187 were investigated. All compounds were tested both in the absence and in the presence of fetal calf serum in the culture medium. The process of collagen synthesis in fibroblasts from colon and skin appears to be affected differently by these regulatory compounds. The most pronounced differences were that the relative collagen synthesis increased in dermal fibroblasts and decreased in colon fibroblasts upon addition of serum. In the presence of serum, interleukin-1 beta inhibited collagen synthesis in skin fibroblasts but not in colon fibroblasts. Dexamethasone suppressed the relative collagen synthesis in skin fibroblasts but not in colon fibroblasts. Transforming growth factor-beta stimulated the collagen synthesis in dermal fibroblasts in the presence of serum, but inhibited the process in colon fibroblasts. Because fibroblasts are the primary sources of collagen needed during wound repair, these results may offer (part of) the explanation why wounds in skin and intestine appear to behave differently under certain conditions.


Non-invasive diagnosis of portal vein occlusion by radionuclide angiography.

The accuracy of non-invasive radionuclide angiography in detecting portal vein occlusion was assessed in 61 patients--10 with portal vein occlusion confirmed by conventional portography, 25 with chronic liver disease and a patent portal vein (mild = 12, severe = 13), and 26 with normal liver function, who served as controls. The median percentage portal venous flow for the portal vein occlusion group was 8% (range 1-30) (consistent with negligible flow) compared with 78% (52-87) for control subjects (p < 0.005) and 68% (61-80) and 49% (23-59) respectively for patients with mild and severe liver disease (p < 0.001 and p < 0.005). At a portal venous inflow of < 20%, the procedure had a specificity of 100% and sensitivity of 90% in diagnosing portal vein occlusion. Non-invasive radionuclide angiography provides a safe and accurate screening method for evaluating portal vein patency or occlusion in the investigation of portal hypertension or before liver transplantation.


A prospective controlled study comparing brush and bile exfoliative cytology for diagnosing bile duct strictures.

Imaging of biliary strictures may suggest malignancy but cytology can provide a tissue diagnosis. The aim of this study is to compare the diagnostic value of brush cytology and bile cytology. Thirty two patients (20 males, 12 females, median age 66 years, range 31-84) with biliary strictures at endoscopic retrograde cholangio pancreatography (24) or percutaneous transhepatic cholangiography (8) had bile cytology and brush cytology. Brushings were taken using a modified Geenan cytology brush (6 Fr gauge, Wilson Cook) passed alongside a guide wire placed through the stricture. Bile was aspirated after insertion of an internal/external catheter or an endoprosthesis. Bile and brushings were examined by one experienced cytologist (AD) and was reported as positive or negative for malignant cells. Twenty nine patients had malignant strictures. Sixteen were confirmed by histology and 13 had malignancy suggested by clinical follow up. Three patients had resection of histologically benign strictures. The overall sensitivity of brush cytology (17 of 29 positive, 59%) was significantly greater than bile cytology (seven of 29 positive, 24%) (p < 0.01) as was the diagnostic accuracy (63 v 31%, p < 0.01). None of the patients had positive bile cytology with negative brush cytology. There were no procedure related complications and the average sampling time once the guide wire had been inserted was less than five minutes. It is concluded that brush cytology is more sensitive than bile cytology and with the technique described is safe and rapid.


Effects of nifedipine on placental blood flow, placental weight and fetal weight in normotensive and spontaneously hypertensive rats.

The effect of nifedipine on placental blood flow was investigated in spontaneously hypertensive rats (SHR) and compared with that in normotensive Wistar Kyoto rats (WKY) by means of the clearance of hydrogen gas generated by electrolysis. The placental blood flow of nifedipine-treated WKY (5, 10 and 25 mg/kg) was significantly (p < 0.05) reduced compared with that of WKY control. On the other hand, the placental blood flow of nifedipine-treated SHR did not change compared with that of SHR control. These data suggest that nifedipine has different effects on placental blood flow in SHR and WKY.


Osteocalcin 24-hour profiles during normal pregnancy.

The interpretation of previous data on osteocalcin during pregnancy has been complicated by the fact that serum levels, at least in nonpregnant women, display a significant circadian variation. In the present study, serum concentrations of osteocalcin were recorded for 24 h in 12 individual women. In 4 nonpregnant women, there were striking diurnal fluctuations during the sampling period, with values ranging from 0.5 to 4.0 ng/ml. One woman who was investigated in the 11th week of pregnancy showed similar fluctuations in osteocalcin concentrations whereas in the 15th and 17th week values were much lower with minor fluctuations. In 4 women investigated during late pregnancy (weeks 34-38), osteocalcin serum levels were extremely low (range 0.2-0.4 ng/ml), often below the detection limit of the assay, and there was no diurnal variation. Also, in 1 lactating woman, osteocalcin serum levels were low (0.3-0.8 ng/ml) and stable. Low osteocalcin values during pregnancy may indicate a reduced bone turnover possibly mediated via an altered estrogen and growth hormone secretion.