Stressful environmental stimuli increase extracellular DOPAC levels in the prefrontal cortex of hypoemotional (Roman high-avoidance) but not hyperemotional (Roman low-avoidance) rats. An in vivo voltammetric study

The effects of a variety of stressful environmental situations on dopamine metabolism in the prefrontal cortex (as assessed by in vivo voltammetry with carbon fiber electrodes) have been compared in two genetically selected lines of rat (Roman high (RHA/Verh) and low (RLA/Verh) avoidance) which differ drastically in their level of emotionality. Heart rate was continuously monitored in these animals (via chronically implanted subcutaneous electrodes) so as to index the emotional reaction to the stressors. An electrochemical signal corresponding to the oxidation of dihydroxyphenylacetic acid (DOPAC) was recorded in the deeper laminae of the anteromedial prefrontal cortex in both lines of rats. Under normal conditions, this signal was stable for at least 4 h and its amplitude was similar in both lines. Introduction of the animals into an unfamiliar environment (30 min), application of a mild tail pinch (10 min) or of a high-intensity loud noise (30 min) or immobilization (20 min) were all associated with an increase in extracellular cortical DOPAC levels in the hypoemotional RHA/Verh line but not in the hyperemotional RLA/Verh line. Similarly, forced locomotion on a rotarod (40 min) provoked a dramatic increase in the amplitude of the cortical DOPAC oxidation peak in RHA/Verh rats and only a mild increase in this parameter in RLA/Verh rats. In RHA/Verh rats, tolerance to this increase was observed when animals were subjected to forced locomotion every day for 5 days. All of the stressful situations investigated provoked an immediate augmentation of heart rate which resumed gradually after cessation of the stressful stimulus; the magnitude and duration of this increase were much greater in RLA/Verh than in RHA/Verh rats. Moreover, in all stress situations, RLA/Verh but not RHA/Verh rats showed behavioral signs of emotional response e.g. defecation, freezing and self-grooming. It is concluded that the increase in cortical dopamine metabolism induced by stress is not connected to the emotional reaction caused by the aversive nature of the stressor but may rather reflect a heightened attention of the animal or activation of cognitive processes in an attempt to cope with the stressor.

Action spectra for nitrate and nitrite assimilation in blue-green algae

Action spectra for the assimilation of nitrate and nitrite have been obtained for several blue-green algae (cyanobacteria) with different accessory pigment composition. The action spectra for both nitrate and nitrite utilization by nitrate-grown Anacystis nidulans L-1402-1 cells exhibited a clear peak at about 620 nanometers, corresponding to photosystem II (PSII) C-phycocyanin absorption, the contribution of chlorophyll a (Chl a) being barely detectable. The action spectrum for nitrate reduction by a nitrite reductase mutant of A. nidulans R2 was very similar. All these action spectra resemble the fluorescence excitation spectrum of cell suspensions of the microalgae monitored at 685 nanometers-the fluorescence band of Chl a in PSII. In contrast, the action spectrum for nitrite utilization by nitrogen-starved A. nidulans cells, which are depleted of C-phycocyanin, showed a maximum near 680 nanometers, attributable to Chl a absorption. The action spectrum for nitrite utilization by Calothrix sp. PCC 7601 cells, which contain both C-phycoerythrin and C-phycocyanin as PSII accessory pigments, presented a plateau in the region from 550 to 630 nanometers. In this case, there was also a clear parallelism between the action spectrum and the fluorescence excitation spectrum, which showed two overlapped peaks with maxima at 562 and 633 nanometers. The correlation observed between the action spectra for both nitrate and nitrite assimilation and the light-harvesting pigment content of the blue-green algae studied strongly suggests that phycobiliproteins perform a direct and active role in these photosynthetic processes.

Influence of ascending serotonergic pathways on glucose use in the conscious rat brain. II. Effects of electrical stimulation of the rostral raphé nuclei

Although lesions of the rostral raphé nuclei have minimal effects on integrated functional activity, as studied by the 2-deoxyglucose technique, the repercussions of activating the ascending serotonergic pathways have yet to be reported in the literature. To examine this question, we studied the consequences of the electrical stimulation of the rostral (median or dorsal) raphé nuclei on local cerebral glucose use in the conscious rat. Glucose use was determined by quantitative autoradiography in 105 defined brain structures. Raphé stimulation increased glucose utilization in a number of well-defined structures and pathways, dorsal raphé stimulation being systematically more effective than median raphé stimulation. Of all the neocortical regions studied, only the somatosensory cortex displayed a columnar and laminar pattern of increased glucose use that was restricted to the somatotopic delineation of the rat's head and face. Increased glucose use was seen in almost all key elements of the extrapyramidal system with the notable exception of the caudate-putamen. The thalamic nuclei that were activated by rostral raphé stimulation included those that subserve the processing of somesthetic, accessory visual and limbic information. Raphé stimulation-induced decreases in local cerebral glucose use were never observed. Almost all of the induced changes could be prevented or obtunded by prior intraventricular administration of the serotonergic neurotoxin 5,7-dihydroxytryptamine, suggesting that the majority of the raphé-induced changes in integrated functional activity were mediated via the activation of serotonergic neurones. The magnitude and pattern of the increases in glucose use could not always be correlated with the regional density of serotonergic innervation nor with the distribution of 5-hydroxytryptamine receptor subtypes in the adult brain. However, the pattern of increased cortical glucose use closely matches the selective serotonergic innervation of the somatosensory cortex found in early postnatal development. Thus, it would appear that the 2-deoxyglucose technique reveals functional units in the cortex that are innervated at an early ontogenic stage. We postulate that the discrete and highly organized changes in integrated functional activity that follow raphé stimulation are due to serotonin acting in a phasic manner on restricted, possibly specialized, postsynaptic structures.(ABSTRACT TRUNCATED AT 400 WORDS)

Serotonergic neuron stimulation modulates thalamocortical glucose use in the conscious rat

We have studied the effects, in the conscious rat, of electrical stimulation of the dorsal or median raphe nuclei on integrated functional activity, as assessed by the quantitative 2-deoxyglucose autoradiographic technique. Stimulation of serotonergic neurons elicits metabolic changes in cortical and thalamic regions that are not limited to those structures known to receive the densest serotonergic innervation. The thalamic nuclei that are activated by raphe stimulation include those that subserve the processing of somesthetic, accessory visual, and limbic information. Raphe stimulation increased cortical glucose use in a laminar and columnar pattern, but only in a highly circumscribed region that corresponds to the somatotopic representation of the rat's face and head. These findings indicate that ascending serotonergic neurons play an important modulatory role in the regulation of thalamocortical glucose use, observations that may be of value in the understanding of the etiology and expression of classic migraine.

Effects of regional denervation on epicardial DC electrograms during coronary occlusion in pigs

Sympathetic innervation of the normal and acutely ischemic myocardium and the effects of regional myocardial sympathetic denervation of the ischemic area on the evolving electrical changes during coronary occlusion were assessed in pigs anesthetized with pentobarbital sodium. The histofluorescence of the adrenergic nerve fibers (glyoxylic acid reaction), which in the normal myocardium were distributed in a diffuse network, decreased slightly after 45 min of occlusion of the left anterior descending (LAD) coronary artery and nearly disappeared after 2 h of ischemia. Topical application of phenol (carbolic acid, 88%) to the coronary arterial wall produced a transmural loss of catecholamine histofluorescence in the distal myocardium supplied by the phenol-treated arterial segment. Mapping of the epicardial direct current (DC) electrograms in sympathetically denervated and in nondenervated sections of the same ischemic area, using three rows of seven cotton-wick electrodes, was performed in eight pigs and validated in eight other nondenervated pigs. During 45 min of LAD occlusion, the denervated area, with respect to the nondenervated region, showed a greater decline in T-Q segment depression after 20 min of ischemia (P less than 0.0001), a lesser degree of S-T segment elevation throughout the study (P less than 0.0001), a delayed development of monophasic potentials (P less than 0.05), a minor degree of S-T segment alternans (P less than 0.0001), and a less marked, but still present, period of transient electrical recovery. Thus acute regional myocardial sympathectomy reduces the magnitude of the local electrical manifestations of acute myocardial ischemia in the in situ pig heart. Also in this model, sympathetic fibers appeared to lose the catecholamine histofluorescence after 2 h of acute ischemia.

Tail-pinch stress increases extracellular DOPAC levels (as measured by in vivo voltammetry) in the rat nucleus accumbens but not frontal cortex: antagonism by diazepam and zolpidem

The effect of a tail-pinch stress on dopamine metabolism in the nucleus accumbens and frontal cortex was investigated in the awake unrestrained rat by measuring extracellular 3,4-dihydroxyphenylacetic acid (DOPAC) levels through the use of in vivo differential pulse voltammetry. Mild tail pressure for 8 min caused a large (maximal effect + 70%) and sustained (more than 2 h) increase in the amplitude of the DOPAC oxidation peak in the nucleus accumbens but not in the prefrontal cortex. A similar increase in DOPAC levels was observed in the nucleus accumbens postmortem 1 h after tail-pinch stress. The tail-pinch induced increase in extracellular DOPAC levels in the nucleus accumbens was antagonized by pretreatment with diazepam (5 mg/kg i.p.) or zolpidem (5 mg/kg i.p.), a novel non-benzodiazepine hypnotic possessing anxiolytic properties. These results suggest that in contrast to other stressors, tail-pinch selectively activates dopaminergic systems projecting to the nucleus accumbens.

[Ring chromosome 18 46,XY,r(18)]

Authors report a ring chromosome 18 (18 r) in a four year old boy, with low birth weight, retarded growth and development, microcephaly and plagiocephaly, horizontal nystagmus, ambiguous genitalia, clinodactyly of the fifth finger, distal axial triradius, whorls pattern in 8 fingers in dermatoglyphic. Serum IgA is lower than 3 mg/dl. Parents karyotype is normal.

Allograft antiglomerular basement membrane glomerulonephritis in a patient with Alport's syndrome

A patient with Alport's syndrome and chronic renal failure received a cadaver kidney graft. Six months after the transplantation he developed 'de novo' crescentic glomerulonephritis mediated by antiglomerular basement membrane antibodies. This rare complication may be attributed to sensitization against usual antigenic determinants of the graft glomerular basement membrane.

A novel carbon fiber implantation assembly for cerebral voltammetric measurements in freely moving rats

In vivo voltammetry has been widely employed to monitor the effects of drugs on dopamine metabolism. In the present study, we report on the use of a newly designed assembly for implantation of carbon fiber microelectrodes for voltammetric measurements in freely moving animals. The assembly consists of an electrode holder and a fixed support (implanted stereotaxically) which is cemented to the rat skull. The working carbon fiber electrode is cemented to the electrode holder, and can be lowered into the fixed support for implantation into the brain parenchyma. This implantation assembly has been used to study the effects of tail-pinch on dopamine metabolism (extracellular DOPAC levels) in the nucleus accumbens and ventral tegmental area of the awake rat. Using this implantation assembly and 3 carbon fiber electrodes, oxidation peaks for ascorbic acid (-100 mV) and DOPAC (+ 100 mV) were recorded in both brain structures. Mild tail pressure for 7 min led to an increase in extracellular DOPAC levels in the nucleus accumbens. A smaller increase was observed in the ventral tegmental area. The DOPAC signals remained elevated for some time after removal of the stressor. This implantation assembly represents a convenient system for implanting carbon fiber electrodes in the freely moving rat, which can be employed to investigate the effects of behavioral manipulation on dopaminergic neurons at the terminal as well as at the cell body level. This microdevice could also be usefully employed for other in vivo electrochemical studies.

Localization and Quantitative Determination of Ferredoxin-NADP Oxidoreductase, a Thylakoid-Bound Enzyme in the Cyanobacterium Anabaena sp. Strain 7119

Thylakoid membrane preparations obtained from mechanically disrupted (sonicated) cells of the cyanobacterium Anabaena sp. strain 7119 show a membrane-bound ferredoxin-NADP(+) oxidoreductase (EC 1.18.1.2) as determined either by specific antibodies or by using the ferredoxin-dependent NADPH-cytochrome c reductase activity, which is a specific test for this enzyme. However, in contrast with higher plant thylakoids, a low yield of the cyanobacterial reductase-only about 20% of the total amount of this protein estimated in whole cell homogenates-was obtained as a membrane-bound form when Mg(2+) was present during the disruption treatment. It is noteworthy that the addition of water-soluble nonionic polymers, namely polyethylene glycol and polyyinylpyrrolidone, dramatically increased the yield of the thylakoid-bound reductase, reaching values up to 80 to 85% of the total enzyme. Using these thylakoid membrane preparations, a quantitative determination of the reductase has been performed for the first time for cyanobacterial thylakoids. The value determined by immunoelectrophoresis-from 8 to 10 nanomoles per micromole of chlorophyll-is clearly higher than those reported for chloroplast thylakoids.

In vivo voltammetric measurement of extracellular DOPAC levels in the anteromedial prefrontal cortex of the rat

Differential pulse voltammetric recordings with carbon fiber electrodes performed in vivo in the anteromedial prefrontal cortex of the rat yielded 3 oxidation peaks at -100, +100 and +300 mV, respectively. Pharmacological manipulations revealed that 3,4-dihydroxyphenylacetic acid (DOPAC) is the main contributor to the oxidation current recorded at +100 mV (peak 2). Thus, systemic administration of FLA 63 did not alter whereas pargyline caused a disappearance of cortical peak 2. Moreover, haloperidol and sulpiride increased peak 2 amplitude both in normal and in N-(2-chloroethyl)N-ethyl-2-bromobenzylamine (DSP4)-lesioned rats. Peak 2 was detected only in those prefrontal cortex regions known to receive a dopamine input. It is concluded that in vivo voltammetry with carbon fiber electrodes is a useful means of monitoring dopaminergic activity in the prefrontal cortex of the rat.

Characterization of cyanobacterial ferredoxin-NADP+ oxidoreductase molecular heterogeneity using chromatofocusing

Chromatofocusing has been used as an analytical tool to check preparations of the enzyme ferredoxin-NADP+ oxidoreductase (EC 1.18.1.2) purified in either the presence or absence of the serine protease inhibitor phenylmethylsulfonyl fluoride from the cyanobacterium Anabaena sp. strain 7119. Only one isoelectric species was found when the crude extract was processed in the presence of the protease inhibitor. Nevertheless, when the inhibitor was omitted, four ionic forms of the enzyme--showing apparent pI's in the range 4.3-4.6--were separated after chromatofocusing of the purified preparation. These forms were found to differ in their specific activities, exhibiting, on the other hand, lower values than the single one obtained in the presence of the protease inhibitor. Analysis by acrylamide gel electrophoresis revealed virtually a single main protein band except for the ionic form of pI 4.39, which was clearly resolved into two active components. Except for the more basic form, which seems to be an homodimer of Mr 80,000, all the protein components were found to be monomeric species in the range Mr 33,000-38,000. These results indicate that the molecular heterogeneity of the ferredoxin-NADP+ oxidoreductase purified from the cyanobacterium Anabaena sp. strain 7119 may result from the activity of a protease present in the whole cell homogenates. On the other hand, these data also point out that chromatofocusing should be considered as an effective technique in the isolation and characterization of the different molecular forms of this enzyme.

GABA mimetics increase extracellular DOPAC (as measured by in vivo voltammetry) in the rat locus coeruleus

Previous studies have suggested that GABA exerts an indirect facilitatory influence on cerebral noradrenergic transmission that is likely to be mediated via GABA-ergic synapses involved in polysynaptic neuronal circuits controlling noradrenergic cell activity. In order to confirm these findings, we have studied the effect of GABA mimetics on extracellular DOPAC in the locus coeruleus (a reliable index of noradrenergic neuronal activity) of the rat through the use of in vivo voltammetry with carbon fibre electrodes. Systemic administration of progabide, its active metabolite SL 75.102, of depamide or muscimol increased the height of the DOPAC oxidation peak in the locus coeruleus; the effect of muscimol was antagonized by co-administration of bicuculline. Intra-locus coeruleus infusion of even a high concentration of muscimol (1 microgram) failed to alter extracellular DOPAC in this area. These results add further weight to the view that GABA exerts a facilitatory influence on noradrenergic neurons (via an increase in their cell firing) which is not effected at the level of their cell bodies or in the surrounding region.

Acute form of visceral leishmaniasis in a 3-month-old infant

The case of a 3-month-old infant who died with an acute form of visceral leishmaniasis is reported. The liver presented an unusual pattern with widespread patchy cellular necrosis besides marked reticulin proliferation and some fibrosis. The marked systemic histiocytic proliferation contrasted with the paucity of Leishman-Donovan bodies, responsible for the negativity of two bone marrow aspirates and a needle biopsy of the liver. Visceral leishmaniasis must be considered in the differential diagnosis of cholestatic syndromes in infancy.

Nephrogenic metaplasia of the ureter

A case of nephrogenic metaplasia of the left ureter occurring in a 7-year-old male child, associated with recurrent urinary infection and previous surgical intervention, is described. This is to our knowledge the third reported case of this entity. Nephrogenic metaplasia involves the transitional epithelium of the urinary tract and results in the formation of structures histologically similar to renal tubules.

Neurochemical studies on the existence, origin and characteristics of the serotonergic innervation of small pial vessels

Substantial concentrations of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA), comparable to those found in brain tissue, were measured in the small pial vessels of the rat, rabbit and cat. Both rat and rabbit pial vessels exhibited a high affinity uptake process with kinetic parameters similar to those identified for the cerebral cortex. Labelled 5-HT, taken up by isolated rabbit pial vessels was released, in a calcium-dependent manner, by potassium-induced depolarization. Various pharmacological manipulations were carried out in the rat. Systemic administration of the 5-HT precursor, 5-hydroxytryptophan and the monoamine oxidase inhibitor, pargyline, significantly increased the concentration of 5-HT in the pial vessels; in contrast, two depleting agents (p-chloroamphetamine and reserpine) and the tryptophan hydroxylase inhibitor, p-chlorophenylalanine, all decreased the perivascular 5-HT levels. A serotonergic antagonist (methysergide) and a 5-HT receptor agonist (MK 212) respectively increased and decreased the concentrations of 5-HIAA in the pial vessels. These pharmacologically induced changes observed in pial vessels were not dissimilar from those noted for cortical tissue. Electrolytic lesions of the nuclei raphes medianus and/or dorsalis markedly decreased the levels of 5-HT and 5-HIAA in these small cerebral arterioles. Electrical stimulation of these nuclei decreased 5-HT although 5-HIAA concentrations tended to increase. A number of conclusions may be drawn from these studies. Thus, there is a serotonergic innervation of the cerebral circulation in several laboratory species which unequivocally originates in the raphé nuclei. Furthermore, these perivascular fibres possess synthetic, storage, release, inactivation and autoregulatory processes for 5-HT which, when further elucidated, may offer some rationale for the treatment of those cerebrovascular diseases in which this neurotransmitter and vasoactive agent is believed to be of pathological importance.

Measurement of 5-HIAA levels in ventricular CSF (by LCEC) and in striatum (by in vivo voltammetry) during pharmacological modifications of serotonin metabolism in the rat

The relationship between the concentrations of 5-hydroxyindoleacetic acid (5-HIAA) in the CSF and in the striatum has been evaluated in the rat by measuring the levels of this metabolite in ventricular CSF (by liquid chromatography coupled with electrochemical detection) and in the striatal extracellular fluid (by in vivo voltammetry) after administration of inhibitors of serotonin synthesis or degradation. Pargyline, NSD 1015 and alpha-propyldopacetamide all caused an exponential decline of 5-HIAA in both CSF and striatum. For a given drug, the rate constants for 5-HIAA disappearance were identical in the CSF and in the striatal extracellular fluid. These results confirm the view that CSF 5-HIAA may serve as a good index of brain serotonin turnover.

Eclectic drainage of subphrenic abscesses

In 196 cases of subphrenic abscess from 1964 through 1979, 56% were attributable to gastric, hepatic, and colonic disease or surgery. Posttraumatic abscesses in younger patients became more frequent. Synchronous suprahepatic and subhepatic abscesses or bilateral abscesses accounted for 19%. Streptococci, Escherichia coli, Klebsiella, and Bacteroides species were the most frequently isolated organisms. Although the overall mortality rate was 40%, the surgical mortality rate decreased from 33% initially to 17% recently. The mortality rate of transperitoneal drainage decreased from 41% to 16%. From 1980 through early 1983, a success rate of 84%, with no fatalities, was achieved in percutaneous radiologic drainage of 25 unilocular abscesses. At present, radiologically guided drainage should be considered for unilocular abscesses and some bilocular ones. Although extraperitoneal, extrapleural surgical drainage remains an expeditious form of treatment, it may give way to radiologic drainage. Transperitoneal drainage is preferable for multifocal abscesses and for many abscesses secondary to complications of intraabdominal surgery.

In vivo voltammetric measurement of extracellular 5-hydroxyindoleacetic acid in the denervated striatum after transplantation of mesencephalic raphe neurons

In vivo differential pulse voltammetry with carbon fiber electrodes was used to monitor extracellular 5-hydroxyindoleacetic acid (5-HIAA) levels in a serotonergic denervated target area, the striatum, before and after transplantation of mesencephalic raphé nuclei into the lateral ventricle in the rat. The amplitude of the electrochemical signal recorded in the striatum on the transplanted side was found to be comparable to that measured in control striatum whereas the signal measured from the contralateral nontransplanted striatum was negligible. These findings suggest that mesencephalic raphé nuclei transplants establish connections with the host tissue.

Inhibitory GABAergic influence on striatal serotonergic transmission exerted in the dorsal raphe as revealed by in vivo voltammetry

In vivo differential pulse voltammetry with electrochemically treated carbon fiber microelectrodes has been used to investigate the anatomical nature of the GABAergic influence on striatal serotonergic transmission in the rat. Lesion studies and pharmacological treatments demonstrated that the electrochemical signal recorded at 300 mV in the striatum probably corresponds to the oxidation of extracellularly released 5-hydroxyindoleacetic acid. Thus, dorsal raphé lesions or systemic administration of alpha-propyldopacetamide, NSD 1015, pargyline and MK212 decreased, whereas reserpine injection increased the amplitude of the signal. Moreover, L-5-hydroxytryptophan administration caused an increase in the signal which was almost completely prevented by pargyline pretreatment. Acute administration of dipropylacetamide (150 mg/kg i.p.) reduced the amplitude of the signal from the striatum, while injection of gamma-acetylenic GABA (200 mg/kg i.p.) was without effect. Repeated (but not acute) treatment with the GABA receptor agonist, progabide (400 mg/kg i.p.b.i.d. for 14 days), led to a pronounced decrease in the amplitude of the signal from the striatum. A similar effect was observed after intradorsal raphé infusion of GABA (10 and 100 micrograms), gamma-vinyl GABA (100 micrograms) and SL 75102 (10 micrograms), a principal metabolite of progabide. In contrast, local injection of the GABA receptor antagonists, bicuculline (1 and 10 micrograms) or R5135 (0.05 microgram), failed to affect the peak amplitude in the striatum. When infused into the dorsal raphé, R5135 (0.05-0.1 microgram) antagonized the diminution of the signal induced by intradorsal raphé infusion of GABA (100 micrograms) or SL 75102 (10 micrograms). Finally, electrolytic lesion of the habenular nuclei completely blocked the diminution of the signal from striatum induced by an intradorsal raphé infusion of GABA (100 micrograms). These results indicate that the inhibitory GABAergic control of striatal serotonergic transmission is exerted at the level of the dorsal raphé cells and depends upon the integrity of the habenulo-dorsal pathway.

Interstellar matter and chemical evolution

The determination of chemical abundances of the interstellar medium is related to three different areas of astronomy: pregalactic conditions, stellar evolution, and chemical evolution of galaxies. The observed abundances permit the testing of theories associated with these areas. Knowledge of the abundances of helium, carbon, nitrogen, and neon relative to the abundance of hydrogen in the interstellar medium puts limits on current models of cosmology, stellar evolution, and galactic evolution.