Estimation of noradrenaline concentrations in the axoplasm of noradrenergic neurones in man.

The plasma concentrations of noradrenaline (NA) and its primary neuronal metabolite, dihydroxyphenylglycol (DOPEG), were examined during graded orthostasis and NA infusion in 13 healthy subjects to estimate the NA concentration difference between the site of neuronal DOPEG formation and that in plasma. Stimulation of NA release by graded orthostasis resulted in similar absolute increments in plasma NA and DOPEG with both plasma concentrations being dependent on the degree of orthostasis. The mean value of the delta DOPEG/delta NA ratio amounted to 0.999 (0.745; 1.341). NA was infused i.v. during two consecutive 30-min periods at constant rates of 0.43 and 0.86 nmol kg-1 min-1, respectively. This infusion resulted in a delta DOPEG/delta NA ratio of 0.048 (0.036; 0.064) for the first and 0.078 (0.067; 0.090) for the second infusion period (p less than 0.01). For each individual subject, the factor quantifying the NA concentration difference between the site of neuronal DOPEG formation and plasma was calculated from the square root of the ratio of 'delta DOPEG/delta NA during orthostasis to delta DOPEG/delta NA during the low rate of NA infusion'. The average NA concentration at the site of neuronal DOPEG formation (i.e. the axoplasm of noradrenergic neurones) was found to be 4.6-fold higher than that in plasma.


Parasympathetic hyperresponsiveness and bradyarrhythmias during apnoea in hypertension.

Voluntary end-expiratory apnoea in a 23-year-old asymptomatic mild hypertensive patient consistently elicited bradyarrhythmias (complete heart block and sinus pause) and sympathetic activation to muscle blood vessels, indicating simultaneous sympathetic and parasympathetic activation during apnoea. The sympathetic bradyarrhythmic response to apnoea was potentiated by hypoxia and eliminated by atropine. Baroreflex activation also attenuated the bradycardic response to apnoea. A 43-year-old hypertensive patient with sleep apnoea also exhibited bradyarrhythmias (sinus arrest for up to 10 s) and a fall in perfusion pressure to less than 50 mmHg during episodes of sleep apnoea. These cardiovascular changes were associated with a reduction in oxygen saturation to levels as low as 35%. Neither patient was on any medication. Simultaneous sympathetic and parasympathetic activation during episodes of apnoea may predispose to cardiovascular catastrophe. These chemoreflex mediated autonomic changes are inhibited by baroreflex activation. We propose that patients with impaired baroreflexes (patients with hypertension or heart failure and premature infants) may be especially susceptible to excessive autonomic responses to chemoreflex stimulation during periods of apnoea. In these patient groups, bradyarrhythmias, hypoxia, hypoperfusion and sympathetic activation during apnoea may predispose to sudden death.


Gender related differences in the cardiovascular responses to upright tilt in normal subjects.

The heart rate and blood pressure responses to head-up tilt of 80 degrees was studied in 20 normal men and 21 normal women aged 20-50 years (mean age 31.1 +/- 7.1 years). The heart rate increase in females during tilt was 73% that of males, whereas the increase in diastolic pressure during tilt was 29% of males. Expressed in relation to values obtained supine, heart rate increases on average 30.3% in men as compared to 21.5% in women whereas diastolic pressure increases by 15.2% in men as compared to an increase of only 4.3% in women. The data indicates that the cardiovascular response of normal females to upright tilt differs significantly from that of normal males. This attenuated responsiveness to orthostasis in women relative to men may predispose women to postural insufficiency and may account for the predominance of symptomatic women with clinically mild dysautonomia.


Presence of neuronal cell bodies in the sympathetic pressor areas of dorsal and ventrolateral medulla inhibiting phrenic nerve discharge in cats.

To examine whether neuronal cell bodies (perikarya) in the pressor areas of dorsal medulla or ventrolateral medulla also modulate respiratory function, phrenic nerve activity was monitored and correlated with the pressor response in chloralose-urethane anaesthetized cats. The animals were paralyzed and artificially ventilated maintaining the end-tidal fractional concentration of CO2 at 0.04-0.05. The same pressor point in the dorsal or ventrolateral medulla was stimulated electrically (rectangular pulse of 20-200 microA, 80 Hz and 0.5 ms) and then chemically (0.25-0.5 M sodium glutamate, 80-200 nl). Areas producing pressor effects in either the dorsal or ventrolateral medulla produced a current-dependent decrease of phrenic discharge. The decrease in Pna was significant when the electrical current reached 50 microA or above. It occurred immediately before the onset of increase in blood pressure. Injection of glutamate to the same pressor point in either the dorsal or ventrolateral medulla produced a similar decrease in phrenic nerve activity. The results suggest that in the pressor areas of dorsal and ventrolateral medulla there are neuronal perikarya that can increase systemic arterial pressure and inhibit phrenic nerve activity. Whether the same or separate neurones are responsible for these responses is to be determined.


Blood flow velocity waveform in the common carotid artery and its analysis in elderly subjects.

We investigated common carotid artery blood flow in 99 elderly nursing home residents using an ultrasonic quantitative blood flow measurement system. Systolic velocity and end-diastolic velocity were obtained from the waveform and classified, using the end-diastolic/systolic volume as Type A which is normal flow (greater than 20% bilaterally), Type B which is unilateral decreased flow (less than 20% unilaterally), Type C which is bilateral decreased flow (less than 20% bilaterally), Type D which is Type C plus a saw tooth pattern and Type E which is no diastolic pattern, i.e. a value of 0 unilaterally or bilaterally. Five per cent of subjects showed Type A of blood flow velocity waveform (normal flow pattern) and about 40% showed Type E (no diastolic pattern). The subjects were divided into three groups according to blood flow velocity waveform. Groups 1, 2 and 3 showed Types A or B, C or D, and E, respectively. The total blood flow volume and mean blood flow velocity of Group 1 were significantly higher than those of Groups 2 and 3 in both the supine and sitting positions. Although both total blood flow volume and mean blood flow velocity of Group 1 decreased significantly in postural change, those of Groups 2 and 3 did not change. These results suggest that total blood flow volume and mean blood flow velocity decrease in proportion to changes in the blood flow velocity waveform.


Muscle chemoreflexes and exercise in humans.

This review focuses on the role afferent nerves from the contracting muscles play in linking muscle metabolism to the cardiovascular adjustments during exercise by means of a 'muscle chemoreflex'. In the 1930s Alam and Smirk provided the first clear evidence that human (and animal) skeletal muscles are innervated by chemosensitive afferents that can evoke increases in arterial blood pressure. They proposed that the purpose of the increase in pressure was to improve blood flow to the active muscles. Subsequent studies have identified the slowly conducting group IV afferents as the major class of fibres participating in the sensory arm of this reflex. Most of these fibres travel via the dorsal roots to the ipsilateral spinal cord where they synapse in the substantia gelatinosa and release substance P or other peptide transmitters. The second order (or higher) neurons cross to the contralateral side of the spinal cord and travel rostrally to stimulate brainstem cardiovascular centres and increase arterial pressure. Current evidence favours the concept that substances associated with muscle acidosis provide the stimulus to the afferents. In humans, chemosensitive afferent activation causes a marked increase in vasoconstrictor efferent muscle sympathetic nerve activity. It is unclear if the muscle chemoreflex improves blood flow to 'underperfused' active muscles by augmenting arterial pressure, or if the increase in sympathetic outflow restrains metabolic vasodilatation to regulate arterial blood pressure during activities like running or cycling.


Argon laser lesions of the retina; occurrence and origin of macrophages.

Macrophage infiltration is frequent in the early stages of various proliferative eye disorders, including subretinal neovascularization. In this study, we set out to establish the origin of macrophages found in an animal model of laser-induced subretinal neovascularization. One primate received several intravenous injections of a colloidal carbon suspension. We then applied standard argon laser lesions to the retina of both eyes, which were enucleated eight days later and sectioned serially for histological examination. A quantitative estimate of carbon-laden and non-laden leukocytes was made based on morphological criteria. Mononuclear leukocytes accumulated in the laser lesions and the percentage of carbon-laden mononuclear leukocytes in relation to the total leukocyte number was higher in the extravascular area of the laser sites than in the systemic circulation. These findings indicate that the majority of mononuclear leukocytes that accumulate at the sites of laser lesions are derived from the systemic circulation.


The safety and efficacy of topical norfloxacin compared with placebo in the treatment of acute, bacterial conjunctivitis. The Norfloxacin-Placebo Ocular Study Group.

Two hundred and eighty-four patients with acute conjunctivitis were enrolled in a double-masked study comparing norfloxacin ophthalmic solution with placebo. The proportion of patients who were clinically improved after 5 days treatment was 88.1% in the norfloxacin group and 71.6% in the placebo group (p less than 0.01). The proportion of patients who had all organisms eradicated, including the coagulase-negative staphylococci, after two to three days treatment was 52.7% for norfloxacin and 23.9% for placebo (p less than 0.01) and 64.7% and 26.3% (p less than 0.01) respectively when the coagulase-negative staphylococci were not included. Adverse experiences occurred in 4.2% of the patients receiving norfloxacin compared to 7.1% of the placebo patients. None of the adverse experiences was serious.


Dacryo-fornix-rhinostomy with two flaps.

The two most frequent sites of obstruction of the lacrimal pathways are under the lacrimal sac, in the ductus lacrimonasalis, and over the lacrimal sac, in the canaliculi. The obstruction of the first type already has a satisfactory solution with the different forms of dacryo-cysto-rhinostomies. Obstruction of the second type has a satisfactory resolution only in a limited number of cases. For patients in whom current treatment methods are unsuccessful, a technique of dacryo-fornix-rhinostomy is presented, consisting in opening a new pathway between the infero-medial conjunctival cul-de-sac and the atrial part of the nasal cavity. A piece of bone is removed from the antero-lateral wall of the atrium nasi, and the bottom of the infero-medial conjunctival fornix is opened to the precedent wound. The exposed nasal mucosa is cut into two flaps, one being sutured to the posterior lip, and the other to the anterior lip of the conjunctival wound. A conformer is maintained in the new path for several weeks. The new path has an almost vertical trajectory, making the flow of tears very easy. Blinking and the movements of the eyes have a pumping effect.


A comparison of FDG PET and IQNB SPECT in normal subjects and in patients with dementia.

Prior studies of patients with dementia have found similar qualitative patterns of cerebral glucose utilization with [18F]2-fluoro-2-deoxyglucose (FDG) PET and of putative muscarinic receptor activity with [123I]3-quinuclidinyl-4-iodobenzilate (IQNB). This raised doubts about whether receptor binding determines IQNB distribution and whether clinical information in IQNB scans is unique. To compare the methods directly, 4 normal volunteers and 7 patients with dementia underwent FDG PET and high-resolution IQNB SPECT scans. In normal subjects, relative regional activity from the paired scans was only weakly correlated (r = 0.29). Some regions (e.g., thalamus, frontal cortex) showed a clear disassociation of activity. In demented patients, IQNB scans tended to show larger defects than FDG scans, although one focal defect appeared only with PET. Results suggest that IQNB SPECT data are not primarily related to general physiological activity or regional cerebral blood flow and are not explained by attenuation or volume-averaging artifacts. Further studies should investigate whether IQNB scanning is a more sensitive in vivo measure of the extent of Alzheimer's disease than is FDG PET.


Binocular vision regained after monocular traumatic aphakia by wearing contact lenses.

In this study 35 patients with monocular traumatic aphakia were enrolled to document the degree of binocular vision gained by optical correction with contact lenses. The most important factors in achieving binocular vision were the interval between formation of the traumatic cataract and surgery and between the operation and starting wearing contact lenses. There was a statistically significant correlation between these two intervals and the achievement of near stereopsis and normal visual acuity.


Choroidal angiography with indocyanine green dye: absorption and fluorescence techniques.

The results of choroidal indocyanine green (I.C.G.) angiography by the absorption and fluorescence techniques are compared. Both techniques were done using the same apparatus, a modified fundus camera, an image intensifier coupled to a solid-state video camera and a U Matic video recorder. Both were performed with the same dye dilution in the same patients, at a 24-hour interval. The light source was the unmodified 50 Watt halogen light bulb of the fundus camera. The angiograms obtained by the absorption and the fluorescence techniques refer to the same chorioretinal area and the same angiographic phase. Comparison of all the angiograms shows that I.C.G. fluorescence angiography provides a better resolution of choroidal vascular details than the absorption technique.


Simultaneous bilateral "malignant glaucoma" attack in a patient with no antecedent eye surgery or miotics.

Malignant glaucoma is a term commonly used to describe a condition characterized by a sudden increase in intraocular pressure, usually occurring after eye surgery. This report describes a case of malignant glaucoma simultaneously presenting in both eyes, with no antecedent eye disease, medication or surgery. As far as we know this is the first report of spontaneous bilateral glaucoma. Both eyes were operated on according to the technique described by Chandler et al. (1), and the condition was solved. We suggest that, despite its rarity in eyes with no antecedent disease or ocular therapy, a surgeon should be aware of this condition.


Rapid eye movement sleep deprivation in elderly patients with concurrent symptoms of depression and dementia.

Rapid eye movement (REM) sleep measures distinguish elderly patients with depression from those with dementia. The authors used a 2-night REM sleep deprivation (RSD) protocol to characterize patients with mixed symptoms of depression and dementia in comparison with patients with "pure" depression or dementia and healthy controls. Mixed-symptom patients resembled dementia patients in baseline sleep measures, but their large change in phasic REM activity following RSD suggests neurobiological similarities to depression. Mixed-symptom patients with stable cognitive impairment had greater REM sleep rebound than those with a more progressive dementing course. These results are consistent with previous neuropathological and neurochemical data.


Chronic postoperative endophthalmitis caused by Propionibacterium acnes.

Persistent intraocular inflammation after cataract surgery with intraocular lens implantation is acquiring importance. Frequently, chronic uveitis or the "toxic lens syndrome" have to be differentiated from bacterial infection. This report describes five cases with chronic postoperative endophthalmitis where the anaerobic bacterium Propionibacterium acnes was found to be the causative organism. Adequate anaerobic culture media and proper sampling from the area around the lens haptics are the most important requirements for the detection of P. acnes.


Preliminary examination of the comorbidity of anxiety and depression in Parkinson's disease.

Significant anxiety in combination with depression may represent a specific depressive subtype in Parkinson's disease (PD). To ascertain the prevalence of this symptom complex, we administered a self-report survey and standardized psychological tests that measure anxiety and depression to 164 PD patients and 150 age-matched healthy spouse control subjects. The reporting of depression in combination with panic/anxiety best differentiated the two populations (38% vs. 8%). Depression and anxiety were highly correlated in relationship to clinical features of PD. Our findings suggest that clinically significant levels of depression and anxiety may frequently coexist in PD. The specific neuropathology of PD may predispose to this pattern of behavioral disturbance.


Cerebral metabolic dysfunction in AIDS: findings in a sample with and without dementia.

Positron-emission tomography was coupled with neurological and neuropsychological evaluation to study regional cerebral activity and neurologic status in two groups. Seventeen patients with full-blown AIDS and 14 seronegative control subjects were studied using [18F]2-fluoro-2-deoxy-D-glucose in a resting state. The AIDS group had relative regional hypermetabolism in the basal ganglia and thalamus; stepwise multiple-regression analyses revealed a significant relationship for the AIDS group between temporal lobe metabolism and severity of dementia on the AIDS Dementia Complex Rating Scale. These results suggest that the basal ganglia, thalamus, and temporal lobes are differentially affected in AIDS.


Spatial attention in HIV-1 infection: a preliminary report.

In a preliminary study, 30 nondemented human immunodeficiency virus (HIV-1) seropositive subjects without acquired immunodeficiency syndrome and 14 seronegative controls performed a reaction time measure of spatial attention. Compared with controls, seropositive asymptomatic subjects showed normal facilitation of reaction time at short cue-target intervals when attention was precued, but symptomatic subjects were impaired. However, asymptomatic subjects showed no evidence of normal inhibition of attention at the cued location at longer cue-target intervals, suggesting possible subtler spatial attentional deficits in this group. Cognitive slowing in HIV-1 infection may have an attentional component, with possible involvement of both automatic and controlled processes.


Auditory event-related potentials in HIV-1 infection: a study in the drug-user risk group.

Features of event-related potentials (ERPs) may be sensitive and clinically useful markers of central nervous system infection by the human immunodeficiency virus (HIV-1); however, this application has not been studied in the risk group of intravenous drug users. Auditory ERPs generated by an "oddball" paradigm were analyzed for 39 male drug abusers as part of a multimodal assessment. Stage of HIV-1 infection was associated with prolongations of P1, N1, and P3 components of the ERP waveform. Only patients with full acquired immunodeficiency syndrome showed statistically significant increases in waveform prolongations. Specific neuropsychological deficits were not related to waveform latency prolongations.


Distribution of Alzheimer's disease-associated protein (ADAP) in 10 human brains.

ALZ50-based enzyme immunoassay was used to study distribution of Alzheimer's disease-associated protein (ADAP) in postmortem brain tissues of 5 Alzheimer's disease (AD) and 5 non-Alzheimer's disease (NAD) subjects. There are at least three AD-associated proteins, including A68. Levels are higher in brain regions with severe neuronal loss in AD: frontal, temporal, hippocampal cortex, and amygdala. No significant ADAP was found in the NAD samples (from 2 age-matched-1 clinically demented-and 3 younger subjects). ADAP levels in four regions of AD brains were not correlated to neuritic plaque count in corresponding regions of matching formaldehyde-fixed hemispheres.


Differential effects of alprazolam and buspirone upon acquisition, retention, and retrieval processes in memory.

A group of 125 healthy young adults was given a memory battery 1 hour after administration of alprazolam (0.5 and 1.0 mg), buspirone (5 and 10 mg), and placebo under single-dose, double-blind conditions. On the wordlist recall battery and a 24-hour retest, alprazolam appeared to impair acquisition and retention in dosages of 1.0 mg; buspirone did not adversely affect test performance at either dosage. On the basis of a 3-stage model of memory, a neuroantomical/neurophysiological model is proposed to explain the selective effects of the benzodiazepines on memory function.


Intractable seizures, compulsions, and coprolalia: a pediatric case study.

A 10-year-old girl with intractable complex partial seizures developed aphasia, coprolalia, and repetitive motor behaviors involving touching, sexual touching, and aggressive acts. Her symptoms subsided following surgical resection of a left anterior temporal lobe ganglioglioma and control of seizures. Possible neurobehavioral implications of the reversibility of this patient's symptoms are discussed.


Balancing risks and benefits: another approach to optimizing diagnostic tests.

In our last two articles, we showed that one can quantify the reduction in uncertainty that results from diagnostic testing, an insight that allowed us to describe a method for optimizing the performance of a test by choosing a cutoff that maximizes its information yield. Although minimizing uncertainty is an important feature of diagnostic testing, there are many situations in which diagnostic tests are most appropriately used to balance risks and benefits associated with the various possible courses of action available to a clinician. This article shows how tests can be used to maximize the "expected utility" associated with a clinical decision.


The cucumber long hypocotyl mutant lacks a light-stable PHYB-like phytochrome.

A novel cDNA sequence homologous to a phytochrome B (phyB) gene that was isolated in a library from tobacco tissue has been used in an Escherichia coli expression system to raise anti-phytochrome B (anti-PHYB) polypeptide-specific monoclonal antibodies. The specificity of these antibodies has been tested by cross-reactivity against purified pea light-labile type 1 and light-stable type 2 phytochromes, with some antibodies reacting with the type 2 and none with the type 1 phytochromes. One such antibody, monoclonal mAT1, has been employed to analyze the phytochrome molecular species present in a photomorphogenic long hypocotyl (lh) mutant of cucumber. The results indicated that the mutant contains wild-type levels of the light-labile type 1 phytochrome polypeptide (PHYA), which has an apparent molecular mass of approximately 120 kD, but shows less than 1% (detection limit) of a light-stable polypeptide recognized by mAT1 in wild-type seedlings. This protein, not detectable in the lh mutant, has the properties of light-stable type 2 phytochrome, has an apparent molecular mass of 116 to 117 kD, and remains at constant levels under continuous low-fluence-rate red light. Therefore, we conclude that the lh mutant lacks at least one type 2 phytochrome-like polypeptide, most probably a phyB gene product. The correlation between the lack of this protein and the deficiency or absence of physiological responses to a light-stable phytochrome species in this mutant helps to identify the physiological roles played by the products of different subfamilies within the phytochrome gene family.


Antisense inhibition of flavonoid biosynthesis in petunia anthers results in male sterility.

Inhibition of flower pigmentation in transgenic petunia plants was previously accomplished by expressing an antisense chalcone synthase (chs) gene under the control of the cauliflower mosaic virus (CaMV) 35S promoter. This chimeric gene was not effective in inhibiting pigmentation in anthers, presumably because the viral CaMV 35S promoter was insufficiently expressed in cell types of this organ in which the pigments are produced. Insertion of the anther box, a homologous sequence found in other genes expressed in anthers, resulted in a modified expression pattern driven by this promoter, as monitored by the beta-glucuronidase (gus) gene. In addition to the basic CaMV 35S expression pattern in anthers, GUS activity was observed in tapetum cells when the modified promoter was fused to the gus gene. This promoter construct was subsequently used to drive an antisense chs gene in transgenic petunia, which led to the inhibition of pigment synthesis in anthers of five of 35 transformants. Transgenic plants with white anthers were male sterile due to an arrest in male gametophyte development. This finding indicated that flavonoids play an essential role in male gametophyte development.


cis-element combinations determine phenylalanine ammonia-lyase gene tissue-specific expression patterns.

The bean phenylalanine ammonia-lyase gene 2 (PAL2) is expressed in the early stages of vascular development at the inception of xylem differentiation, associated with the synthesis of lignin precursors. This is part of a complex program of developmental expression regulating the synthesis of functionally diverse phenylpropanoid natural products. Analysis of the expression of PAL2 promoter-beta-glucuronidase gene fusions in transgenic tobacco plants showed that functionally redundant cis elements located between nucleotides -289 and -74 relative to the transcription start site were essential for xylem expression, but were not involved in expression in leaf primordia and stem nodes or in establishing tissue specificity in petals. The -135 to -119 region implicated in xylem expression contains a negative element that suppresses the activity of a cryptic cis element for phloem expression located between -480 and -289. The functional properties of each vascular element are conserved in stem, petiole, and root, even though the xylem and phloem are organized in different patterns in these organs. We conclude that the PAL2 promoter has a modular organization and that tissue-specific expression in the vascular system involves a negative combinatorial interaction, modulation of which may provide a flexible mechanism for modification of tissue specificity.


Mutations in the D1 subunit of photosystem II distinguish between quinone and herbicide binding sites.

The structure-activity relationships of the plastoquinone QB binding domain in the D1 subunit of photosystem II (PSII) were investigated by characterization of mutations introduced in the D1 protein. Eight novel point mutations in the gene psbA, which encodes D1, were generated in the cyanobacterium Synechocystis PCC6803 by site-specific mutagenesis in vitro. The effects of the resulting modifications in D1 on electron transfer in PSII and on herbicide binding were analyzed. The results extend the structural analogies between the secondary quinone binding site in D1 and in subunit L of the photosynthetic reaction center in purple bacteria. The involvement of Phe255, Ser264, and Leu271 of D1 in plastoquinone binding and electron transfer in PSII was established. An indirect effect of Tyr254 on the binding of QB was demonstrated. Changes in binding of herbicides and QB to D1 as a result of the mutations revealed specific interactions between amino acid residues in D1 and the plastoquinone and distinguished between the binding sites of QB and herbicides.


Proaleurain vacuolar targeting is mediated by short contiguous peptide interactions.

Targeting of soluble proteins to the plant vacuole is mediated by determinants that reside in the polypeptide. We identified the vacuolar targeting determinant of aleurain, a plant vacuolar thiol protease, by incorporating different sequences from proaleurain into the secreted thiol protease, proendoproteinase B (proEP-B), and vice versa. The targeting fates of the chimeric proteins were analyzed by transient expression in electroporated tobacco protoplasts. The targeting determinant SSSSFADSNPIR is positioned at the N terminus of the aleurain propeptide, and its substitution into the propeptide of EP-B caused vacuolar targeting of the resulting chimeric protein. This determinant can be divided into two smaller determinants, SSSSFADS and SNPIR, each of which is sufficient to target proEP-B chimeras to the vacuole, but with lower efficiency. These smaller determinants interact in a positive manner because the combined determinant SSSSFADSNPIR targeted proEP-B with an efficiency greater than each of the smaller determinants alone. Accordingly, the efficiency of aleurain targeting was decreased when either of the smaller determinants was disrupted by replacement with similarly positioned proEP-B sequences. Further experiments on proaleurain identified an additional determinant, VTDRAAST, adjacent to the SSSSFADSNPIR determinant that is also necessary for efficient vacuolar targeting. Our results provide evidence that efficient vacuolar targeting of this thiol protease in plant cells is mediated by the combined action of smaller contiguous determinants; two of these alone are sufficient for vacuolar targeting.


Both internal and external regulatory elements control expression of the pea Fed-1 gene in transgenic tobacco seedlings.

In previous studies using leaves of light-grown transgenic tobacco plants, we have shown that sequences located within the transcribed region of the pea Fed-1 gene (encoding ferredoxin I) are major cis-acting determinants of light-regulated mRNA accumulation. However, we show here that these internal sequences are less important for the Fed-1 light response in etiolated tobacco seedlings than they are in green leaves and that upstream elements confer organ specificity and contribute significantly to Fed-1 light responses in etiolated material. Light effects mediated by upstream response elements are thus most pronounced during the initial induction of gene activity, whereas internal elements play a more prominent role in modulating Fed-1 expression once the gene is already active.


A maize embryo-specific gene encodes a proline-rich and hydrophobic protein.

A gene from maize that encodes a hybrid proline-rich protein (HyPRP) formed by two well-defined domains, proline-rich and hydrophobic, respectively, has been characterized at the level of its structure and expression. The proline-rich domain is composed of elements PPYV and PPTPRPS, similar to those found in PRP proteins from soybean. The hydrophobic domain is rich in cysteine and is similar to seed proteins, mainly to a soybean hydrophobic seed protein. In maize, HyPRP is encoded by a single gene, and its mRNA accumulates in immature maize zygotic embryos, with a maximum accumulation between 12 and 18 days after pollination. The HyPRP mRNA can also be detected in ovary prior to pollination. In situ hybridization experiments on embryo sections show an expression of the gene in scutellum and in nonvascular cells from the embryo axis. Functional hypotheses related to HyPRP are discussed.


A carrot somatic embryo mutant is rescued by chitinase.

At the nonpermissive temperature, somatic embryogenesis of the temperature-sensitive (ts) carrot cell mutant ts11 does not proceed beyond the globular stage. This developmental arrest can be lifted by the addition of proteins secreted by wild-type cells to the culture medium. From this mixture of secreted proteins, a 32-kD glycoprotein, designated extracellular protein 3 (EP3), that allows completion of somatic embryo development in ts11 at the nonpermissive temperature was purified. On the basis of peptide sequences and biochemical characterization, EP3 was identified as a glycosylated acidic endochitinase. The addition of the 32-kD endochitinase to ts11 embryo cultures at the nonpermissive temperature appeared to promote the formation of a correctly formed embryo protoderm. These results imply that a glycosylated acidic endochitinase has an important function in early plant somatic embryo development.


A mitochondrial DNA sequence is associated with abnormal pollen development in cytoplasmic male sterile bean plants.

Cytoplasmic male sterility (CMS) in common bean is associated with the presence of a 3-kb unique mitochondrial sequence designated pvs. The pvs sequence encodes at least two open reading frames (297 and 720 bp in length) with portions derived from the chloroplast genome. Fertility restoration by the nuclear restorer gene Fr results in the loss of this transcriptionally active unique region. We examined the effect of CMS (pvs present) and fertility restoration by Fr (pvs absent) on the pattern of pollen development in bean. In the CMS line, pollen aborted in the tetrad stage late in microgametogenesis. Microspores maintained cytoplasmic connections throughout pollen development, indicating aberrant or incomplete cytokinesis. Pollen-specific events associated with pollen abortion and fertility restoration imply that a gametophytic factor or event may be involved in CMS. In situ hybridization experiments suggested that significant reduction or complete loss of the mitochondrial sterility-associated sequence occurred in fertile pollen of F2 populations segregating for fertility. These observations support a model of fertility restoration by the loss of a mitochondrial DNA sequence prior to or during microsporogenesis/gametogenesis.


Cytokinins and auxins control the expression of a gene in Nicotiana plumbaginifolia cells by feedback regulation.

Both cytokinin (N6-benzyladenine [BA]) and auxin (2,4-dichlorophenoxyacetic acid [2,4-D]) stimulate the accumulation of an mRNA, represented by the cDNA pLS216, in Nicotiana plumbaginifolia suspension culture cells. The kinetics of RNA accumulation were different for the two hormones; however, the response to both was transient, and the magnitude of the response was dose dependent. Runoff transcription experiments demonstrated that the transient appearance of the RNA could be accounted for by feedback regulation of transcription and not by the induction of an RNA degradation system. The feedback mechanism appeared to desensitize the cells to further exposure of the hormone. In particular, cells became refractory to the subsequent addition of 2,4-D after the initial RNA accumulation response subsided. A very different response was observed when the second hormone was added to cells that had been desensitized to the first hormone. Under such conditions, BA produced a heightened response in cells desensitized to 2,4-D and vice versa. These findings support a model in which cytokinin further enhances the auxin response or prevents its feedback inhibition. The hormone-induced RNA accumulation was blocked by the protein kinase inhibitor staurosporin. On the other hand, the protein phosphatase inhibitor okadaic acid stimulated expression, and, in particular, okadaic acid was able to stimulate RNA accumulation in cells desensitized to auxin. This suggests that hormone activation involves phosphorylation of critical proteins on the hormone signaling pathway, whereas feedback inhibition may involve dephosphorylation of these proteins. The sequence of pLS216 is similar to genes in other plants that are stimulated by multiple agonists such as auxins, elicitors, and heavy metals, and to the gene encoding the stringent starvation protein in Escherichia coli. It is proposed that this gene family in various plants be called multiple stimulus response (msr) genes.


Characterization of a plant scaffold attachment region in a DNA fragment that normalizes transgene expression in tobacco.

Using a low-salt extraction procedure, we isolated nuclear scaffolds from tobacco that bind specific plant DNA fragments in vitro. One of these fragments was characterized in more detail; this characterization showed that it contains sequences with structural properties analogous to animal scaffold attachment regions (SARs). We showed that scaffold attachment is evolutionarily conserved between plants and animals, although different SARs have different binding affinities. Furthermore, we demonstrated that flanking a chimeric transgene with the characterized SAR-containing fragment reduces significantly the variation in expression in series of transformants with an active insertion, whereas a SAR fragment from the human beta-globin locus does not. Moreover, the frequency distribution patterns of transgene activities showed that most of the transformants containing the plant SAR fragment had expression levels clustered around the mean. These data suggest that the particular plant DNA fragment can insulate the reporter gene from expression-influencing effects exerted from the host chromatin.


Binding sites for two novel phosphoproteins, 3AF5 and 3AF3, are required for rbcS-3A expression.

Previous studies of boxes II (-151 to -138) and III (-125 to -114), binding sites for the nuclear factor GT-1 within the -166 deleted promoter of the ribulose-1,5-bisphosphate carboxylase-3A (rbcS-3A) gene, suggested that GT-1 might act in concert with an additional protein to confer light-responsive rbcS-3A expression. In this work, S1 analysis of RNA isolated from transgenic tobacco plants carrying mutant rbcS-3A constructs led to the identification of two short sequences located at the 5' and 3' ends of box III that are required for expression. These two sequences serve as binding sites for two novel proteins, 3AF5 and 3AF3. Gel shift studies using tetramerized binding sites for both 3AF5 and 3AF3 showed that complexes with faster mobilities were formed using nuclear extracts prepared from dark-adapted plants compared with those from light-grown tobacco plants. Phosphatase treatment of extracts from light-grown plants resulted in the formation of complexes with faster mobility. Although the binding of 3AF3 to its target site is dependent upon phosphorylation, the binding of 3AF5 does not appear to be affected by its phosphorylation state. These results suggest that the phosphorylated forms of both 3AF5 and 3AF3 are required for -166 rbcS-3A expression but that the mechanisms differ by which phosphorylation regulates the activities of 3AF5 and 3AF3.


Sequences flanking the hexameric G-box core CACGTG affect the specificity of protein binding.

The CACGTG G-box motif is a highly conserved DNA sequence that has been identified in the 5' upstream region of plant genes exhibiting regulation by a variety of environmental signals and physiological cues. Gel mobility shift assays using a panel of G-box oligonucleotides differing in their flanking sequences identified two types of binding activity (A and B) in a cauliflower nuclear extract. Competition gel retardation assays demonstrated that the two types of binding activity were distinct. Type A binding activity interacted with oligonucleotides designated as class I elements, whereas type B binding activity interacted strongly with class II elements and weakly with class I elements. A third class of elements, null elements, did not exhibit any detectable binding under our assay conditions. Gel retardation analysis of nonpalindromic hybrid G-box oligonucleotides indicated that hybrid elements of the same class exhibited binding affinity commensurate with the affinity of the weaker element, hybrid class I/II elements exhibited only type B binding, and hybrid class I/null and class II/null elements did not show any detectable binding activity. These binding activities can be explained by the affinity of bZip G-box binding homo- or heterodimer subunits for G-box half sites. These experiments led to a set of classification rules that can predict the binding activity of all reported plant G-box motifs containing the consensus hexameric core. Tissue- and/or development-specific expression of genes containing G-box motifs may be regulated by the affinity of G-box proteins for the different classes of G-box elements.


Homodimeric and heterodimeric leucine zipper proteins and nuclear factors from parsley recognize diverse promoter elements with ACGT cores.

Four short nucleotide sequences (boxes I to IV) contribute to the light responsiveness of the parsley chalcone synthase promoter. The sequence-related boxes II and III resemble several plant, viral, and bacterial promoter elements that share ACGT core sequences and are associated with diversely regulated genes. We have analyzed the binding characteristics and protein-protein interactions of factors from nuclear extracts and of three putative leucine zipper (bZIP) transcription factors potentially involved in the regulation of this promoter. These common plant regulatory factors (CPRFs) bind specifically to boxes II and III as well as other ACGT-containing promoter elements (hex1, Em1a, and as-1), though with markedly different affinities. Intact bZIP domains are crucial for CPRF binding to DNA. Distinct ensembles of nuclear factors bind to boxes II and III, despite their sequence similarity. The parsley CPRFs bind to DNA as dimers, selectively form heterodimeric DNA binding complexes, and interact with nuclear proteins.


The small genome of Arabidopsis contains at least six expressed alpha-tubulin genes.

The goal of our investigations is to define the genetic control of microtubule-based processes in a higher plant. The available evidence suggests that we have achieved our first objective: the characterization of the complete alpha-tubulin and beta-tubulin gene families of Arabidopsis. Four additional alpha-tubulin genes (TUA2, TUA4, TUA5, and TUA6) of Arabidopsis have been cloned and sequenced to complete the analysis of the gene structure for all six alpha-tubulin genes detectable on DNA gel blots of Arabidopsis genomic DNA hybridized with alpha-tubulin coding sequences. TUA1 and TUA3 were characterized earlier in our laboratory. Noncoding gene-specific hybridization probes have been constructed for all six alpha-tubulin genes and used in RNA gel blot analyses to demonstrate that all six genes are transcribed. The six genes encode four different alpha-tubulin isoforms; TUA2 and TUA4 encode a single isoform, as do TUA3 and TUA5. Two-dimensional protein gel immunoblot analyses have resolved at least four alpha-tubulin isoforms from plant tissues, suggesting that all of the predicted TUA gene products are synthesized in vivo.


The small genome of Arabidopsis contains at least nine expressed beta-tubulin genes.

The small genome of Arabidopsis contains at least nine expressed beta-tubulin (TUB) genes, in contrast to the large genomes of vertebrate animals, which contain a maximum of seven expressed beta-tubulin genes. In this study, we report the structures of seven new TUB genes (TUB2, TUB3, TUB5, TUB6, TUB7, TUB8, and TUB9) of Arabidopsis. The sequences of TUB1 and TUB4 had been reported previously. Sequence similarities and unique structural features suggest that the nine TUB genes evolved by way of three branches in the plant beta-tubulin gene evolutionary tree. Two genes (TUB2 and TUB3) encode the same beta-tubulin isoform; thus, the nine genes predict eight different beta-tubulins. In contrast to the alpha-tubulin (TUA) genes with their divergent intron patterns, all nine TUB genes contain 2 introns at conserved positions. Noncoding 3' gene-specific hybridization probes have been constructed for all nine TUB genes and used in RNA gel blot analyses to demonstrate that all nine genes are transcribed. Two-dimensional protein immunoblot analyses have resolved at least seven different beta-tubulin isoforms in Arabidopsis, indicating that most, if not all, of the TUB transcripts are translated.


Preferential expression of an alpha-tubulin gene of Arabidopsis in pollen.

The pool of tubulin protein in tissues of Arabidopsis is provided by the expression of multiple alpha-tubulin (TUA) and beta-tubulin genes. Whereas most tubulin genes are expressed in many tissues, previous evidence suggested that the TUA1 gene might be expressed primarily in pollen. We now report a detailed analysis of TUA1 expression during Arabidopsis development. In RNA from tissues of dissected flowers, TUA1 transcripts were detected only in stamens and mature pollen. Chimeric genes containing TUA1 5' flanking DNA fused to the beta-glucuronidase (GUS) coding region were used to create transgenic Arabidopsis plants. Plants containing a chimeric gene with 533 bp of 5' flanking sequence were analyzed by histochemical assay to localize GUS expression within the plant. The blue product of GUS enzyme activity accumulated very rapidly in postmitotic pollen grains. Much lower levels of GUS activity were detected in anthers with uninucleate pollen grains, in flower receptacles, and in a few vegetative tissues. Analysis of 5' deletions of the TUA1 promoter suggested that 97 bp of 5' flanking DNA is sufficient to drive GUS expression in pollen and young anthers, whereas at least 380 bp is required to detect GUS expression in the receptacle. Examination of the TUA1 promoter sequence revealed several motifs that are repeated within the TUA1 promoter and are similar to sequences in other pollen-specific promoters.


A geminivirus replication protein is a sequence-specific DNA binding protein.

The genome of the geminivirus tomato golden mosaic virus (TGMV) consists of two circular DNA molecules designated as components A and B. The A component encodes the only viral protein, AL1, that is required for viral replication. We showed that AL1 interacts specifically with TGMV A and B DNA by using an immunoprecipitation assay for AL1:DNA complex formation. In this assay, a monoclonal antibody against AL1 precipitated AL1:TGMV DNA complexes, whereas an unrelated antibody failed to precipitate the complexes. Competition assays with homologous and heterologous DNAs established the specificity of AL1:DNA binding. AL1 produced by transgenic tobacco plants and by baculovirus-infected insect cells exhibited similar DNA binding activity. The AL1 binding site maps to 52 bp on the left side of the common region, a 235-bp region that is highly conserved between the two TGMV genome components. The AL1:DNA binding site does not include the putative hairpin structure that is conserved in the common regions or the equivalent 5' intergenic regions of all geminiviruses. These studies demonstrate that a geminivirus replication protein is a sequence-specific DNA binding protein, and the studies have important implications for the role of this protein in virus replication.


Internal editing of the maize chloroplast ndhA transcript restores codons for conserved amino acids.

The NADH dehydrogenase subunit A (ndhA) gene from maize chloroplasts encodes a highly conserved peptide, which at several positions could be restored to consensus sequences by potential C-to-U editing of the codons involved. This gene was, therefore, chosen for analysis of its mRNA sequence in the form of amplified cDNA. A comparison of this cDNA sequence with the plastome-encoded ndhA sequence reveals four C-to-U editing sites, thereby demonstrating as a novel finding that chloroplast editing can also affect internal mRNA positions. All the edited codons restore amino acids that are conserved in the ndhA-encoded peptides of other chloroplast species. Alignment with homologous mitochondrial NADH-ubiquinone reductase subunit 1 (nad1) sequences of plant and even nonplant species shows that two of the editing positions restore universally conserved amino acids and that one editing site is even shared with nad1 mRNA of plant mitochondria. No editing sites could be detected in the cDNA derived from transcripts of the maize chloroplast RNA polymerase alpha-subunit (rpoA) gene.


The effects of hypocalcaemia due to a 4-hour infusion of Na2EDTA solution on various blood and urine analytes in dairy cows and a comparison of these effects between cows with high and low erythrocyte potassium concentrations.

Six HK (high erythrocyte potassium) and 7 LK (low erythrocyte potassium) dairy cows were subjected to a 4-h intravenous infusion of 4.7% Na2EDTA solution to induce and maintain hypocalcaemia. Blood samples taken immediately before infusion, hourly for 7 h, and at 24 h after commencement of infusion were subjected to determination of concentration (or count) of 16 analytes. The mean changes in concentrations (or counts) of the various blood analytes were calculated for the periods 0-4, 4-7, 7-24, and 0-24 h after commencement of the infusion for all cows combined, and then separately for the HK and LK groups of cows. Plasma Ca(PCa), plasma inorganic phosphorus (PiP) and plasma potassium (PK) showed significant decreases during the 4-h infusion period and were still below pretreatment levels 24 h later. AST, CPK, PCVs and white cell-counts (WCCs) showed significant early increases which were still significantly elevated 24 h later. Plasma magnesium (PMg) and erythrocyte Na(ENa) and K(EK) all showed delayed changes which still persisted 24 h later. Significant between-group differences were present for PCVs which increased significantly more in the LK than the HK group during the infusion period, for PCa which showed a greater increase in the HK cows than the LK cows during the 4-7 h early clinical recovery period, and for plasma bilirubin (PBil) which showed a greater increase from 0 to 24 h in the HK group than in the LK group. Urine samples, collected before infusion, 4-7 h and 24 h after commencement of the infusion, were subjected to analysis for glucose, protein, pH, 'blood' and ketones. Most cows showed increases in urinary glucose, protein and 'blood'.


Bilateral thalamocortical projection in hedgehogs: evolutionary implications.

In adult hedgehogs with large unilateral cortical deposits of fluorescent somatopetal tracers, labelled perikarya were found not only in the ipsilateral but also contralateral thalamus. An exceptionally large number of contralaterally labelled neurons was seen in the ventrolateral nucleus, also at a considerable distance from the midline. Deposits of one of two different tracers in the frontoparietal cortex of each hemisphere appear to label different perikarya in each ventrolateral nucleus. This projection to the contralateral cortex in hedgehogs does not resemble thalamo-cortical connections in either adult or developing brains of other mammalian species. Among amniotes, only in pigeons have contralateral projections from the thalamus to the telencephalon been described. The somatosensorimotor system of hedgehogs may be the only known mammalian remnant of primitive vertebrate thalamocortical organization. Whether primitive or derived, the bilateral thalamocortical projection in hedgehogs shows that hedgehog brains cannot be uncritically taken to represent brains of primate ancestors.


Investigation of some pathophysiological effects of prolonged hypocalcaemia in sheep induced by infusing Na2EDTA solution for 4 hours daily on three consecutive days.

Hypocalcaemia was induced in a group of five aged Merino ewes (with low erythrocyte potassium status) by the intravenous infusion of 4.7% Na2EDTA solution for 4 h daily on 3 consecutive days. A similar control group was infused with 5.0% dextrose solution (10 ml/h) for the same period. Blood samples were taken immediately before infusion each day, hourly for 7 h, then at 08:00 each morning for a further 5 d. Studies were made on the changes in plasma (P) Ca, PNa, PK, PMg, PProtein (PProt), P inorganic phosphorus (PiP), erythrocyte (E) Na, EK, EMg, PCVs, and mean corpuscular cell volumes (MCV). Significant decreases occurred in PiP concentrations but these were only temporary, which suggests that PiP is unlikely to be involved in the complications of prolonged hypocalcaemia. Significant prolonged decreases in PNa, PK and EK and significant prolonged increases in PCVs suggested that fluid replacement therapy supplemented with Na and K may be worthy of further study in the treatment of ruminants affected by apparent biochemical or physiological complications to prolonged hypocalcaemia.


The role of the cortex in play fighting by rats: developmental and evolutionary implications.

Play is a distinctive behavior of young mammals, especially mammals with a well-developed forebrain. For this reason it is thought that there may be a relation between forebrain evolution and highly elaborated play behavior. This study investigated the contribution of the cortex to play behavior by comparing play in control and neonatally decorticated rats (Rattus norvegicus). Play fighting in rats involves the combination of attack by one rat and defense by the recipient, with pinning arising when specific patterns of defense are used. Whether paired with another decorticate or with an intact pairmate, decorticates attacked pairmates as frequently as did intacts, and they were just as likely to defend against playful attacks as were intacts. Where decorticates differed from intacts was on a measure of pinning, in which one rat stands over a supine partner, decorticate rats displayed a reduction of 50% relative to control rats during the juvenile stage in which play is most pronounced (days 25 to 40). Juvenile decorticate rats adopted types of defensive responses which were less likely to result in the pinning configuration. Thus, a reduced pinning frequency reflects an altered pattern of defense, not a reduced level of play fighting. Rather, the decorticate patterns of defense were typical of those defensive responses displayed by adult rats. That is, decorticate juveniles exhibit a precociously mature pattern of playful defense. As intact controls mature, they come to resemble the decorticates in their defensive responses, and hence the difference in pinning frequency between decorticate and intact pairs diminishes. This suggests that the cortex may inhibit the escalation of defense in juveniles and thus promote prolonged ventral-ventral contact during play fighting. The results further suggest that the cortex is involved in the development of adult behavioral skills by facilitating juvenile play.


Short latency auditory evoked potentials recorded from non-anaesthetized thoroughbred horses.

The Brainstem Auditory Evoked Potential (BAEP) is a recording of the electrical activity of the brainstem following an acoustic stimulation. Up to seven peaks may be identified within 10 ms, and are labelled I to VII. The first five of these peaks are of most clinical importance, and in normal horses, peaks I, III and V are always present at stimulus intensities of 70-100 dB. Repeated sampling of clinically normal subjects at different stimulus intensities has enabled mean latency values to be determined for the ipsilateral and contralateral peaks I, III and V, and also for the interpeak latencies (IPLs) at each intensity. The maximum, normal, absolute latency for ipsilateral peak I was 1.86 ms, for peak III, 3.53 ms and for peak V, 5.52 ms. The equivalent contralateral values were 2.50 ms, 4.44 ms and 5.59 ms. The maximum, normal, contralateral IPL for I-III was 1.78 ms, that for III-V was 2.26 ms and for I-V was 3.76 ms. The maximum, normal, contralateral IPLs were 2.17 ms for I-III, 1.41 ms for III-V and 3.32 ms for I-V. If a peak or peaks are absent or delayed, or the IPL is greater than expected, the patient can be determined to have abnormal brainstem or auditory nerve conduction. The amplitudes of peaks I and V were measured, and the ratio of amplitudes was determined, to find the normal V:I values. At a stimulus intensity of 100 dB, the ipsilateral ratio was 0.49 +/- 0.19, and the contralateral value 1.49 +/- 0.48. Dispersal values were also calculated, by dividing the height of the III-V complex by its duration. For a stimulus intensity of 100 dB, the ipsilateral dispersal value was 0.416 +/- 0.104 microV/ms, and the contralateral value of 0.473 +/- 0.074 microV/ms. A range of normal values for both V:I ratio and dispersal were calculated. Height, weight and inter-aural distance were measured, and the relationship of the various peaks and IPLs to these variables was ascertained by statistical analysis. For the ipsilateral values, the correlation between the latency of wave V, and III-V and I-V IPLs and weight were significant (P less than 0.01). Significant correlations were found between weight and the latency of contralateral waves III (P less than 0.05) and V (P less than 0.05) and the I-III (P less than 0.01) and I-V (P less than 0.001) IPLs.(ABSTRACT TRUNCATED AT 400 WORDS)


Changes in factor VIII activity and von Willebrand factor antigen concentration with age in dogs.

The factor VIII activity of 38 German shepherd puppies, 6-12 weeks old, submitted for diagnosis of haemophilia A was measured. Eight of these puppies had values higher than would be expected for haemophiliacs, but less than the reference range for adult dogs. A further sequential study of 21 puppies (6-26 weeks of age) indicated that the factor VIII activity of puppies is generally less than that of adult dogs until about 14 weeks of age. Changes in the concentration of von Willebrand factor antigen in the puppies were irregular. These variations are probably not sufficient to interfere with accurate diagnosis of haemophilia A in most affected young dogs, but may interfere with the detection of heterozygotes in young bitches.


Discrimination of visual stimuli representing prey versus non-prey by the praying mantis Sphodromantis lineola (Burr.).

Adult, female praying mantids, Sphodromantis lineola (Burr.), were presented with seventy, flat black rectangles which moved toward the mantids (in the horizontal plane) against a white background. The lengths of the lures' edges parallel to their direction of movement, 1(1), were 1.5, 3, 6, 12, 18, 24, 30, 54, 72, or 114 mm; the edge lengths perpendicular to movement direction, 1(2), were 1.5, 3, 6, 12, 18, 24, or 30 mm. Mantids emitted the most predatory behaviors to square lures (1[1] = 1[2]) for which 1(1, 2) = 3-12 mm, and to 'worm' lures (1[1] greater than 1[2]) for which 1(2) = 1.5-6 mm. 'Anti-worm' lures (1[1] less than 1[2]) were poor releasers of predatory behavior. These results reconcile seemingly discrepant findings between studies that have presented mantids with various types of oscillating, rotating and/or three-dimensional lures. Further, the results indicate that like other terrestrial predators, such as toads, prey recognition by S. lineola is approximate and based on the spatiotemporal relationships between the features of moving objects (i.e. worm versus anti-worm). These findings are congruent with data on mantid prey selection in the wild.


Experimental Yersinia enterocolitica placentitis in sheep.

A strain of Yersinia enterocolitica of O serogroup 6,30 isolated from the liver of an aborted ovine fetus was inoculated intravenously into a group of pregnant ewes at about 90 days gestation and produced placentitis with abortion or delivery of infected lambs about 50 days later. Y. enterocolitica of the same serogroup was recovered from the necrotic placental cotyledons and most other fetal tissues and could be isolated from vaginal discharges of the ewes for a least 2 weeks after abortion. Histological changes were consistent with an acute bacterial necrotizing placentitis and systemic infection of the fetus. Subsequent pregnancies in the ewes proceeded to term without evidence of infection.


Differences in optokinetic and vestibular ocular reflex performance in teleosts and their relationship to different life styles.

Horizontal eye movements in response to vestibular and optokinetic stimulation were investigated in 20 species of marine and fresh water teleosts. Most species performed spontaneous saccadic eye movements in light and in darkness. Successive saccades occurred either at irregular intervals and in different directions (few species), or in bursts of smaller saccades in one direction followed by saccades in the opposite direction (majority of species). Thus, in the latter group the lines of sight shifted cyclically from one side to the other about every 10-15 s. Eye movement responses in goldfish and toadfish were prototypical for two major functional groups. Optokinetic and vestibular nystagmus in the goldfish were much more regular and attained significantly higher gains than in the oyster toadfish. Optokinetic afternystagmus (OKAN) and per-/postrotatory nystagmus lasted about 10-12 s in the goldfish, but only 2-3 s in the oyster toadfish. Bilateral labyrinthectomy in goldfish resulted in optokinetic gains and OKAN durations that were very close to those of intact toadfish. These results indicate the presence (in goldfish) and the absence (in toadfish) of a functioning velocity storage network, respectively. Other non-ostariophysan teleosts failed to show a 'goldfish-like' response pattern as well. Ostariophysan species differed in their reflex performance as well. A 'goldfish-like' response pattern was observed in five of the seven cypriniform species and in two of the four characiform species but not in the four siluriform species. Positively correlated, combined response properties suggest that some species are better equipped for gaze stabilization at higher velocities than other species. These behavioral differences may parallel different specializations in locomotor pattern and mode of life. Absence of a functioning velocity storage network in bottom-dwelling teleosts (as in Amphibia) may be related to the sporadic, slow locomotion of these species and the resulting small requirements for continuous gaze stabilization during self-motion at higher velocities.


A preliminary study of serum haptoglobin concentration as a prognostic indicator of ovine dystocia cases.

Serum samples were collected prior to the correction of dystocia in 45 sheep and from nine sheep following a normal parturition. Serum samples collected from a group of 16 non-pregnant ewes acted as non-pregnant controls. The mean serum haptoglobin concentration was significantly elevated (P less than 0.01) in those dystocia cases where dead lambs were present in utero compared to those ewes which had live lambs delivered. While the number of cases presented in this study is small, there is an indication that sheep with a serum haptoglobin concentration above 1.0 g/l represent a poor surgical risk. The three ewes which died following a caesarean operation had markedly elevated serum haptoglobin concentrations prior to surgery indicating an inflammatory reaction. Five ewes with a haptoglobin concentration of 0.4 g/l made an uneventful recovery following a caesarean operation.


In vitro HRP-labeling of the fasciculus retroflexus in the lizard Gallotia galloti.

In order to test the usefulness of the in vitro HRP-labeling technique in the brains of small lizards, the fasciculus retroflexus was labeled in isolated brains of young specimens of the lizard Gallotia galloti by means of HRP applied with the tip of a micropipette located approximately midway along the descending course of the tract. Cells in the medial and lateral habenular nuclei were labeled retrogradely. Anterograde transport showed the course of the fasciculus retroflexus, first dorsoventrally into the paramedian prerubral tegmentum and then longitudinally into the isthmic nucleus interpeduncularis. Some fibers spread dorsally into the mesencephalic and isthmic tegmental fields. A substantial bundle continues caudally into nucleus raphe parvocellularis. Other fibers diverge rostral-wards from the point of inflexion of the fasciculus, coursing longitudinally in the medial forebrain bundle into the basal telencephalon. Some fibers course rostrally from the nucleus habenularis lateralis in the stria medullaris and could be followed to the dorsal septum.


Afferent connections of the habenular complex in the lizard Gallotia galloti.

Afferents to the habenular complex were studied by means of in vitro horseradish peroxidase retrograde labeling and anterograde control experiments in the lizard Gallotia galloti. The medial habenular nucleus was found to receive abundant afferent fibers from the nucleus of the posterior pallial commissure and the nucleus septalis impar. More restricted input comes from the nucleus eminentiae thalami and the nucleus of the stria medullaris. The lateral habenular nucleus is innervated by various fiber groups originating from the bed nucleus of the anterior commissure, the diagonal band nucleus, the lateral preoptic area, the anterior entopeduncular nucleus, the lateral hypothalamic and mammillary areas, the nucleus of the stria medullaris, the area tegmentalis ventralis and a scattered neuronal subpopulation in the large-celled dorsolateral nucleus of the dorsal thalamus. Habenulopetal fibers generally follow the stria medullaris, but hypothalamic, entopeduncular and dorsal thalamic afferents course through the dorsal peduncle of the lateral forebrain bundle in a transthalamic route. Mesencephalic ventral tegmental afferents ascend through the tractus retroflexus.


Phylogenetic changes in the connections of the lateral preglomerular nucleus in ostariophysan teleosts: a pluralistic view of brain evolution.

The connections of the lateral preglomerular nucleus were examined with the fluorescent tracer DiI in a cyprinid, a characin, a catfish and a gymnotoid species. In all of these taxa the lateral preglomerular nucleus receives inputs from the torus semicircularis and projects to the telencephalon. Cytoarchitectural and topological data further support the hypothesis that the lateral preglomerular nucleus is homologous among the species examined. A cladistic analysis of species differences, however, reveals that some connections of the lateral preglomerular nucleus have changed dramatically during the course of evolution. Some of the cell groups that are interconnected with the lateral preglomerular nucleus have increased in size, while others have decreased. Increases in the number of subdivisions of cell groups are frequently associated with size increases, but they may also be associated with size decreases. Some of the connections between cell groups have increased in strength, whereas others have decreased in strength, but these connectional changes bear no simple relationship to phylogenetic changes in the size of the cell groups. Phylogenetic increases in the number of subdivisions within a cell group may be associated with selective gains of connections, but they may be associated also with selective losses of connections or with no major changes in connections. Furthermore, several cell groups and connections appear to have evolved 'de novo', whereas others have disappeared during the course of evolution. Finally, the individual cell groups within this system of interconnected nuclei have changed largely independently of one another. These findings establish that brain evolution is not dominated by a single type of phylogenetic change.


Partition of function in the morphological subdivisions of the lateral geniculate nucleus of the tammar wallaby (Macropus eugenii).

Extra-cellular recordings from single cells in the dorsal lateral geniculate nucleus (dLGN) of the tammar wallaby, Macropus eugenii, were made to find out whether the stratification of the nucleus could be correlated with the receptive field properties of units. Retinofugal fibres terminate in the lateral geniculate nucleus of the wallaby in nine interleaved eye-specific layers. These may be grouped into a lateral alpha segment of six laminae and a medial beta segment of three, in which the cells are less densely packed. Ninety percent of the geniculate neurons recorded from in the alpha segment gave brisk responses to stimulation of their receptive fields. Cells with sluggish responses predominated in the beta segment, but there was also a sizable minority of cells with brisk responses that were indistinguishable from those recorded in the alpha segment. In contrast, other response properties were rarely differentiated in individual layers. Thus, in most layers, the numbers of cells with transient or sustained responses were not significantly different, and this was also true for cells with ON- or OFF- responses. For each of these response pairings, however, the numbers of one type (ON- and transient) predominated in every layer. The accumulation of this laminar distinction lead to significant differences in the alpha and beta segments and in the nucleus as a whole. We conclude that cells in the individual layers of the dLGN of the tammar wallaby show no evidence of having receptive field properties in common that might correlate with separate functional streams. There is a functional segregation of receptive field properties between the alpha and beta segments. The organization of these two segments resembles that of the A and the C layers of the dLGN in cats and, possibly, the magnocellular and koniocellular components of the dLGN in primates. These broad similarities in functional partition of the dLGN of different species suggests that this aspect of the organization of the nucleus is independent of lifestyle.


The pattern of trunk lateral line afferents and efferents in the rainbow trout (Salmo gairdneri).

The primary projections of the mechanosensory posterior lateral line nerve of the rainbow trout Salmo gairdneri, a teleost without lateral line specializations, were studied by applying horseradish peroxidase (HRP). The afferents project nearly exclusively to the nucleus medialis and a small nucleus caudalis in the hindbrain, and to the eminentia granularis. In addition, there is a sparse projection to the cerebellum, but a projection to the magnocellular nucleus is lacking. The afferent projection to the lateral part of the eminentia granularis is more dense than the projection to the medial nucleus, as shown by image processing of the HRP labeling. The efferent fibers originate from a bilateral pair of large octavolateral nuclei in the hindbrain. Characteristic for these nuclei are their large, fusiform and bipolar neurons. Another specific feature is the oblique orientation of the somata, with the main dendritic shaft coursing ventrolaterally and the axonal shaft coursing dorsomedially. The axons of the efferent neurons bifurcate. The shape, orientation and size of the efferent somata are the same in the entire efferent nucleus. In contrast to other teleosts, the occurrence of efferent somata found contralaterally (21%) is substantial. The part of the octavolateral efferent nucleus innervating the neuromasts of the trunk is estimated to contain at most 150 cell bodies unilaterally.


Activation of mesocortical dopaminergic system in the rat in response to neonatal medial prefrontal cortex lesions. Concurrence with functional sparing.

Neonatal lesions of the medial part of the rat prefrontal cortex (mPFC) (performed at the age of 6 days) resulted in a sparing in the performance of spatial delayed alternation (SDA) and an increase in dopaminergic (DA) innervation. The increased DA innervation was primarily observed in the remaining part of the mPFC. The DA fibre density was considerably higher in the non-ablated part of the mPFC, and the fibres were thicker with more large varicosities compared with sham-operated controls. Biochemical measurements showed a 3.5-fold increase in DA concentration in the remaining part of the mPFC of the animals with neonatal lesions when compared with the mPFC of sham-operated animals. In addition the DA metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were increased. The metabolite/transmitter ratios, indicating DA utilisation, did not significantly differ from controls. The increased DA innervation and the increased concentration of DA and its metabolites in the animals with neonatal lesions further support our hypothesis that the mesocortical DA system is involved in the neural mechanism of sparing of function observed after neonatal mPFC lesions. However, sparing of function in animals with no discernable mPFC forces us to conclude that this DA response cannot be the only factor involved in the mechanism of sparing of function.


Interaction of opioid peptide-containing terminals with dopaminergic perikarya in the rat hypothalamus.

Both direct pituitary and indirect CNS mechanisms have been postulated for the influence of opiate agonists on prolactin secretion. By examining the interactions between terminals of neurons containing opioid peptides and hypothalamic TH-positive cell bodies, this paper addressed the anatomical basis for the latter mechanism. Initial electron microscopic studies directly demonstrated contact between opioid peptide terminals and dopaminergic cell bodies and provided some visual criteria for assessing opioid-dopamine interactions at the light microscopic level. Using these guidelines, we examined the rates of contact on both A12 and A14 neurons of each of the three opioid peptide families: pro-enkephalin, pro-dynorphin, and pro-opiomelanocortin (POMC). For A14 neurons, many of which project to the posterior pituitary, contact rates were estimated at 15, 20, and 5% for dynorphin, Met-enkephalin, and ACTH (a POMC derivative), respectively. In contrast, the A12 dopamine neurons, which regulate prolactin secretion by inhibition, showed a roughly 70% contact rate with dynorphin axons (P less than 0.001) with Met-enkephalin and ACTH contact rates remaining low at 20 and 5% respectively. Contact frequency varied significantly during the estrus cycle only with dynorphin contacts on A12 neurons. Proestrus and diestrus (less so) showed a small but significant (P less than 0.05) elevation in contact rates versus estrus, male, lactating and pregnant groups. No other significant difference emerged among these groups. On the basis of these observations, we conclude that dynorphin represents a significant and specific factor in the innervation of A12 dopamine neurons. This relationship may account for some if not most of the influence of opiate agonists and antagonists on prolactin secretion.


Relationship between soma diameter and oxidative enzyme activity of alpha-motoneurons.

In order to determine whether there is a relationship between soma diameter and oxidative enzyme activity of alpha-motoneurons, we investigated the alpha-motoneurons innervating the different portions within a rat gluteus medius muscle. Two fluorescent neuronal tracers, Nuclear yellow and Fast blue, were used for labeling motoneurons innervating the deep (predominance of oxidative fibers) and superficial (predominance of non-oxidative fibers) portions of the muscle. An inverse relationship between soma diameter and oxidative enzyme activity was not seen in the motoneuron pool innervating either the deep or superficial portions. When the two portions were taken together, however, the inverse relationship was seen. The inverse relationship seemed to be demonstrated in a motoneuron pool which intermingled motoneurons innervating oxidative fibers and motoneurons innervating non-oxidative fibers. These results suggest that the oxidative enzyme activity of alpha-motoneurons is not correlated strictly with their soma size. We consider that the oxidative enzyme activity of alpha-motoneurons is correlated with oxidative enzyme activity of the muscle unit.


Involvement of postsynaptic G proteins in hippocampal long-term potentiation.

The possible involvement of postsynaptic guanosine 5-triphosphate (GTP)-binding proteins (G proteins) in long-term potentiation (LTP) was studied in rat hippocampal slices, using whole-cell recording techniques. The inclusion of guanosine 5'-O-(2-thiodiphosphate) (GDP beta S) or guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) in the recording pipette significantly reduced or abolished the baclofen-induced hyperpolarization of pyramidal neurons, which indicates uncoupling of the signal transduction from G protein-coupled receptors by these compounds. Both GDP beta S and GTP gamma S significantly attenuated the magnitude of LTP in the fimbria-CA3 synapses, but not in the mossy fiber-CA3 synapses. GTP gamma S did not attenuate LTP in the Schaffer-CA1 synapses. The effects of guanine nucleotide analogs on fimbrial LTP were reversed by postsynaptic depolarization during high frequency stimulation. These results suggest that postsynaptic G proteins may be involved in the generation of LTP in the fimbrial synapses, possibly by affecting membrane depolarization during high frequency afferent activation.


Responses of hippocampal cells can be conditioned during paradoxical sleep.

To test the hypothesis that new associations can be acquired during sleep, we developed a conditioning paradigm in which both conditioned (CS) and unconditioned (US) stimuli were non-awakening intra-cerebral stimulations. The CS was a stimulation of the Medical Geniculate body and the US a stimulation of the Central Grey. An increase in hippocampal multiunit activity to CS was taken as the conditioned response. CS-US pairings were presented across 14 sessions, with 15 trials per session and a 24-h inter-session interval. Three groups were studied: in a group the CS-US pairings were given during the awake state (group W), and in two groups pairings were presented during sleep, either slow-wave sleep (group SWS) or paradoxical sleep (group PS). In the last group, to test the possibility of transfer to the awake state of the hippocampal response acquired in PS, the CS alone were presented interspersed with periods of wakefulness. Results showed that, before pairing, CS presentation induced no change in hippocampal multiunit activity in the three groups. After pairing, no hippocampal response to CS presentation occurred in SWS. In contrast, in the W group and in the PS group, a marked increase in hippocampal activity appeared to CS. The hippocampal response in the PS group developed progressively across sessions; it occurred only two sessions later than in the W group. Moreover, when the CS-evoked response reached the asymptotic level in PS, the presentation of CS alone in awake animals elicited the hippocampal response. These results suggest that a cellular conditioning can be established during PS and that the cellular conditioned response developed in PS can be transferred to the awake state.


Differential identification and localization of adenylyl cyclase and glucose transporter in brain using iodinated derivatives of forskolin.

Two radioiodinated derivatives of forskolin, [125I]6-IHPP-Fsk and [125I]7-IHPP-Fsk, were synthesized as specific ligands for adenylyl cyclase and glucose transporter, respectively. [125I]6-IHPP-Fsk bound to bovine brain homogenates with a Kd of 9 nM and binding was inhibited by forskolin but not 1,9-dideoxyforskolin, cytochalasin B, or D-glucose. [125I]7-IHPP-Fsk bound to bovine brain homogenates at two classes of binding sites with Kd's of 56 nM and 4.7 microM; cytochalasin B and D-glucose inhibited 75% of the high affinity binding while having no effect on the low affinity binding. [125I]6-IHPP-Fsk and [125I]7-IHPP-Fsk were used to localize adenylyl cyclase and glucose transporter in rat brain by receptor autoradiography. The pattern of binding obtained with [125I]6-IHPP-Fsk was similar to that observed using [3H]forskolin to detect adenylyl cyclase. In contrast, the pattern of binding obtained with [125I]7-IHPP-Fsk was similar to that observed by others using [3H]cytochalasin B to detect glucose transporter. These iodinated ligands are selective for adenylyl cyclase and glucose transporter and require significantly shorter exposure times to yield autoradiographs than tritiated ligands.


The influence of different concentrations of volatile anesthetics on the threshold for cortical spreading depression in rats.

We studied the influence of halothane and isoflurane on the electrical threshold for triggering spreading depression (SD) in rats. While the N-methyl-D-aspartate (NMDA) antagonist ketamine dramatically increased the triggering threshold (and blocked propagation), neither volatile agent had any dose-related effect. High doses of both agents slightly slowed SD propagation rate. These results indicate that volatile agents in typical anesthetic doses can be used in studies of SD in rats, and also suggest that these agents have little effect on NMDA receptor-mediated neurotransmission.


Overgrowth and pruning of dendrites in adult rats recovering from neocortical damage.

Unilateral lesions to the forelimb representation (FL) area of the rat sensorimotor cortex caused a time-dependent increase in the dendritic arborization of layer V pyramidal neurons in the contralateral homotopic cortex. The increase in arborization was maximum at 2-3 weeks after the lesion, following which there was a partial reduction in dendritic branching. These neural morphological changes may be related to post-lesion behavioral changes in the use of the forelimbs.


An analogue of Joro spider toxin selectively suppresses hippocampal epileptic discharges induced by quisqualate.

The anticonvulsant effect of 1-naphthylacetyl spermine, an analogue of Joro spider toxin (JSTX), was studied against seizures induced by quisqualate (QUIS), a non-NMDA agonist, as assessed electrophysiologically and behaviorally in freely moving rats. Electrodes were implanted into right dorsal hippocampus and an injection cannula for drugs into right ventricle. The pretreatment with JSTX analogue significantly inhibited both of QUIS-induced hippocampal discharges (80-11%) and generalized tonic clonic seizures (100-33%) in a dose-dependent manner, whereas JSTX had no effect on seizures induced by quinolinate, a NMDA agonist. The paper provides the first direct evidence that the JSTX analogue exerts a potent and selective suppression of hippocampal epileptic discharges mediated by non-N-methyl-D-aspartate (non-NMDA) receptors.


Antagonism of calcitonin-induced anorexia by chronic, but not acute, tricyclic antidepressants in the rat.

Intraperitoneal or intracerebral injections of calcitonin in the rat produce several behavioral and hormonal effects which have some analogies with the human depressive syndrome. To determine if calcitonin effects are sensitive to antidepressant drugs, the ability of antidepressants and other psychotropic drugs to interact with calcitonin-induced anorexia was tested. The results show that chronic treatments (21 days) with tricyclic, or with tetracyclic, antidepressants significantly tend to neutralize the anorectic effect of calcitonin. Other antidepressants and other psychotropic drugs had no significant effect. The acute administration (24 h) of clomipramine did not antagonize the effect of calcitonin, and even significantly enhanced it. These results allow the author to propose the effects of calcitonin in the rat as a new animal model of depression, and to raise the hypothesis that a possible mechanism of action of tricyclic antidepressant treatments is to counteract the effects of certain brain peptides.


Presumptive GABAergic feedback input to the frog olfactory bulb: a double labelling study with retrograde axonal tracing and GABA immunohistochemistry.

The localization of gamma-aminobutyric acid (GABA)-immunoreactive neurons that project to the main olfactory bulb in the frog was studied by combining GABA immunohistochemistry with retrograde axonal tracing. Double-labelled neurons were observed in the dorsal, medial and lateral pallial areas involved in reciprocal connections with the main olfactory bulb. GABA-immunoreactive cell bodies constituted only a part of the population of bulbopetal neurons in each pallial region. This suggests that bulbopetal neurons in the frog pallium belong to neuronal populations which differ in their neurotransmitter specificities. The bulbopetal GABA-immunoreactive pallial neurons may be the source of GABAergic feedback input to the frog main olfactory bulb.


Environmental modulation of behavioral tolerance in spinal rats.

We previously reported that the antinociceptive effect of morphine on the thermal tail withdrawal reflex (tail flick, TF) was reduced in rats that had practiced the TF response prior to morphine administration. This phenomenon, termed behavioral tolerance, was observed even when rats were spinally transected following the TF tests. The present experiments were conducted to determine whether such retention of behavioral tolerance after spinal transection was dependent on prior experience with the TF procedure, or whether other nociceptive pretreatments would also reduce opiate antinociception on the TF test in spinal rats. Separate groups of rats were pretreated with either nociceptive thermal TF or Hot Plate (HP), or mechanical Tail Pinch (TP) stimuli, as well as non-nociceptive exposure to the experimental context )Habituation) or No Pretreatment. Approximately half of the rats were spinally transected after their respective pretreatment, while the other half were left intact. When Intact rats were subsequently tested on the TF at 30, 60, 120 and 180 min after morphine administration, only the TF pretreated group was tolerant, relative to the Non-pretreated control group. However, this was a transient effect, and was only significant at the first, 30-min test; there was no difference among the groups in the total duration of antinociception across all the time points. When spinal rats were tested after morphine administration, there was also an overall significant difference among the groups at 30 min. In this case, the differences were maintained across all time points.(ABSTRACT TRUNCATED AT 250 WORDS)


Amphetamine-induced changes in behavior and caudate extracellular acetylcholine.

In vivo microdialysis was used to study the effects of amphetamine on caudate extracellular acetylcholine and to compare these effects to the drug-induced behavioral response profile. Consistent with an inhibitory dopamine/acetylcholine interaction, the dopamine receptor agonist, apomorphine, decreased acetylcholine concentrations, while the dopamine receptor antagonist, haloperidol, increased acetylcholine. In contrast, an intermediate dose of amphetamine (1.75 mg/kg), did not significantly alter acetylcholine levels. Furthermore, a higher dose of amphetamine (5.0 mg/kg) promoted a two-fold increase in acetylcholine levels, and the increase paralleled the appearance of oral stereotypies in these animals. These results suggest that the effects of amphetamine on caudate acetylcholine, which may be implicated in the appearance of stereotyped behaviors, are not strictly dependent on caudate dopamine receptor activation.


Mechanisms of C6 glioma cell and fetal astrocyte migration into hydrated collagen I gels.

Fetal basal ganglia astrocytes and C6 glioma cells were plated on the surface of 1.5 cm thick hydrated collagen I wafers. Both cell types migrated through the entire thickness of the wafer within 1 day after plating. The collagen in the wafer was digested and the fine collagen I fibrils were clumped into large strands. By 2-3 days, the collagen strands were digested from the wafers and replaced by a mass of fetal astrocytes or C6 cells joined by their processes. The collagen I digestion and cell migration suggested protease production. In a second series of experiments, cultured C6 cells and E14 fetal astrocytes were immunohistochemically stained for the presence of plasminogen activators as an index of protease production. Both tissue (tPA) and urokinase (uPA) types were observed. Fetal astrocytes and C6 cells were also positive for guanidinobenzoatase, a serine protease associated with migrating cells. These data demonstrate that rapid migration of the cells on and through collagen I fibrils is concomitant with expression of plasminogen activators and proteases which can either activate or function as collagenases and release the cells from the substrate.


Expression of c-fos mRNA in acute and kindled cocaine seizures in rats.

In situ hybridization for c-fos mRNA was performed on brain sections (a) from rats after an acute cocaine-induced seizure or from saline-injected controls and (b) from rats after their first cocaine-kindled seizure, as well as from rats that had not yet developed cocaine-kindled seizures (but were exposed to the same amount of cocaine as those that did exhibit convulsions) and from saline-injected controls. Increased expression of c-fos mRNA was observed in animals demonstrating cocaine-induced seizures acutely or following pharmacological kindling. Rats that experienced acute seizures after cocaine (65 mg/kg) showed pronounced increase in expression of c-fos mRNA in the dentate gyrus of the hippocampus and olfactory bulb. Increases were also observed in several other limbic cortical regions, as well as the striatum and ventromedial hypothalamic nucleus (VMH). In rats that were injected daily with an initially subconvulsive dose of cocaine-HCl (40 mg/kg), the cocaine-kindled seizures induced elevations in c-fos mRNA in the same brain regions as with an acute cocaine-induced seizure with the single exception of the VMH. These findings not only suggest the involvement of limbic, cortical and striatal structures in the cocaine-induced seizure, but also raise the possibility that alterations in the proto-oncogene c-fos and its subsequent impact on gene expression could play a role in the changes in neural excitability associated with cocaine-induced kindling.


Hypothalamic electrical activity that relates to the pulsatile release of luteinizing hormone exhibits diurnal variation in ovariectomized rats.

The multiunit activity (MUA) was recorded in the arcuate nucleus-median eminence region in freely moving ovariectomized rats maintained under controlled lighting conditions (lights on 05.00-19.00 h) over a period of 24 h. The MUA of each rat had been confirmed to exhibit characteristic increases (volleys) in association with pulses of luteinizing hormone. In 6 MUAs examined, the frequency of MUA volleys was significantly greater in the dark period than in the light period, suggesting a diurnal variation in the release of luteinizing hormone-releasing hormone in the ovariectomized rat.


A neurofilament protein antibody selectively labels a large ganglion cell type in the human retina.

An antibody (SMI-32) raised against the non-phosphorylated form of the neurofilament protein triplet (NFP) revealed immunoreactivity in the soma and dendritic arborization of a group of large ganglion cells in the human retina. In addition, a population of smaller somas was also faintly labeled with this antibody in the ganglion cell layer. The completely stained cells amounted to 44,000 and were non-uniformly distributed across the retina with a peak density of 100 cells/mm2 in the retinal periphery. The soma sizes increased about two-fold and dendritic field sizes about 3-fold with retinal eccentricity. The immunoreactive dendrites branched in the vitread sublamina of the inner plexiform layer. The dendritic branching pattern of these cells indicated that they correspond to the previously described shrub cells. Antibodies against NFP and neuropeptide Y showed colocalization of these markers in all of the completely stained cells.


Excitatory amino acids and the actions of cocaine.

Antagonists of the N-methyl-D-aspartate (NMDA) type of excitatory amino acid (EAA) receptors blocked cocaine-induced stereotypy, locomotor stimulation and convulsions. These effects in general appear to involve selectively NMDA type of receptors. The results suggest that NMDA-activated systems are an integral component in the reaction sequences involved in the expression of several behavioral effects of cocaine.


Activity of neurons in the rostral medulla of the halothane-anesthetized rat during withdrawal from noxious heat.

The physiological and pharmacological properties of two classes of putative nociceptive modulatory neurons have been extensively characterized in the rostral ventromedial medulla (RVM) of the barbiturate-anesthetized rat. 'On-cells' show a burst of activity, and 'off-cells' a sudden pause immediately preceding the occurrence of nocifensor reflexes. In the present study, we have characterized the reflex-related activity of RVM neurons in halothane-anesthetized rats to determine whether the properties of these neurons are dependent on barbiturate anesthesia. Both on- and off-cells were identified in this preparation. Repeated noxious stimulation was associated with a high level of ongoing activity in on-cells, and a low level in off-cells. These data thus demonstrate that the previously described reflex-related changes in RVM neuron activity are not specific to barbiturate-anesthetized preparations, and that a failure to demonstrate off-cells in some studies may result from these neurons being inactive following repeated testing with noxious stimuli.


Functional correlates of a three-component spatial model of the alpha rhythm.

We applied a three-component (temporal, occipital and parietal) spatial model to EEG data obtained from 46 young and 11 elderly subjects. With closed eyes the mean alpha frequency was 9.51 Hz for the temporal, 9.88 Hz for the occipital and 10.14 Hz for the parietal component. The power of the occipital component was larger than that of the others. With open eyes it was reduced to the same level as the temporal and parietal components. The power of the occipital component decreased significantly with age.


Hippocampal kindling induced paired-pulse depression in the dentate gyrus and paired-pulse facilitation in CA3.

Rats received high frequency (100 Hz, 1 s) hippocampal stimulations that evoked afterdischarges (ADs) in a partial kindling model of epilepsy. Kindled rats were given 15 ADs over 3 days. Control rats received the same stimulation pulses at 0.17 Hz (low frequency stimulation, LFSs). Subsequent to in vivo stimulations, hippocampal slices were obtained from the rats and extracellular field responses were recorded in the CA3 cell layer following CA1 stratum radiatum stimulation, and in the granule cell layer of the dentate gyrus (DG) following perforant path stimulation. At the DG, the paired-pulse facilitation of the population spike was depressed in the kindled than the control group, on 1 day or 23 days post ADs/LFSs. The excitatory postsynaptic potential (EPSP) responses in DG following single or paired pulses were not different between kindled and control slices. At CA3, paired-pulse facilitation of both the population spike and the population EPSP was increased in the kindled compared to the control group.


Identification of neuron subpopulations in the rat vestibular ganglion by calbindin-D 28K, calretinin and neurofilament proteins immunoreactivity.

Immunocytochemical and morphometric analyses were combined to demonstrate the presence of neuron subpopulations in the rat vestibular ganglion. Monoclonal antibodies reacting with neurofilament proteins (NF), calbindin-D 28K (CaBP) and calretinin (CaR) were used. Three subpopulations were identified: (1) CaBP- and CaR-positive neurons were the largest neurons (16%) and they were also highly NF-immunoreactive; (2) exclusively NF-positive neurons; (3) unlabelled neurons, representing about two-thirds of the population.


Adenosine receptor agonists inhibit the release of gamma-aminobutyric acid (GABA) from the ischemic rat cerebral cortex.

The effects of CPA (a selective A1 receptor agonist), NECA (a mixed A1 and A2 receptor agonist), and CGS 21680 (a selective A2 receptor agonist) on the ischemia-evoked release of gamma-aminobutyric acid (GABA) from rat cerebral cortex was investigated with the cortical cup technique. Cerebral ischemia (20 min) was elicited by four vessel occlusion. In control animals, superfusate GABA increased from a basal level of 206 +/- 26 nM (mean +/- S.E.M., n = 18) to 10,748 +/- 3,876 nM during the reperfusion period. Pretreatment with adenosine receptor agonists failed to affect basal levels of GABA release. However, CPA (10(-10) M), NECA (10(-9) M), and CGS 21680 (10(-8) M) significantly suppressed the ischemia-evoked release of GABA. The ability to block the ischemia-evoked release of GABA was not evident when the adenosine receptor agonists were administered at higher concentrations. Thus, the selective activation of either A1 or high-affinity A2a adenosine receptors results in an inhibition of ischemia-evoked GABA release.


Movement features and H-reflex modulation. I. Pedalling versus matched controls.

Modulation of soleus H-reflex magnitude over a cycle of leg movement and the adjustment of controls to account for it were explored. During pedalling, H-reflex magnitudes in all nine subjects were highest in the power producing phase and lowest in recovery. Stimulation intensity was standardized. Compared to sitting, these reflexes were significantly depressed (P less than 0.05). The sitting condition was modified in one experiment, so that the angles of the limb joints and the contraction level of soleus were matched to their values, measured at 13 equi-spaced points, around the pedal cycle. This matching resulted in some modulation of the H-reflex around the pedal cycle, when sitting. When the contraction of tibialis anterior was added to these changes to the seated control, this modulation came closer to that seen during movement. Movement-specific modulation of the reflex was now harder to identify. These data raise the question of whether the three features presently used for matching are causative in the movement modulation of the soleus H-reflex and whether they represent effects arising from centrally descending or peripheral sources.