Characterization of the S'-subsite specificity of bovine pancreatic alpha-chymotrypsin via acyl transfer to added nucleophiles.

The S'-subsite specificity of bovine pancreatic alpha-chymotrypsin was investigated by acyl transfer reactions using a series of amino-acid- and peptide-derived nucleophiles. The nucleophilic efficiency covers a range of more than three orders of magnitude, reflecting the specificity of the acyl transfer process. Positively charged H-Arg-NH2 was the most efficient nucleophile of the series while peptides with free carboxyl groups show poor nucleophilic behaviour.

Unilateral decortication affects muscarinic cholinergic receptor binding in rat basal forebrain.

The distribution of muscarinic acetylcholine receptors (including the M(1)-receptor subtype), beta-adreno receptors, and noradrenaline uptake sites was studied in cholinergic basal forebrain nuclei (medial and lateral septum, ventral and dorsal limb of the diagonal band, substantia innominata and nucleus basalis of Meynert) of adult rats 25 days after unilateral decortication, using quantitative receptor autoradiography. Unilateral neocortex suction lesion resulted 25 days postoperatively in significant enhancements of [(3)H]quinuclidinyl benzilate binding to the total population of muscarinic acetylcholine receptors in both sides of the substantia innominata (> 55%) and of the nucleus basalis of Meynert (> 45%) compared to sham-operated control rats. Additionally, increased binding levels in the medial septum (59%) and dorsal limb of the diagonal band (48%) were found in unilaterally decorticated rats.

Stereotaxic preparation of circumscribed cortical areas from rat brain for biochemical studies.

A method for the rapid dissection of circumscribed areas of rat cortex is described. The technique does not depend on skull-derived landmarks but uses for stereotaxic orientation the cross-point of the interhemispheric gap with the caudal margin of the cortex. An application of this dissection method to the biochemical analysis of cholinergic markers within the hindlimb representation of the primary somatosensory cortex revealed that both the activity of the enzyme choline acetyltransferase as well as the binding of [3H] quinuclidinyl benzilate to muscarinic cholinergic receptors do not seem to be affected drastically three days after unilateral transection of the sciatic nerve.

Interaction of bacterial glucose-6-phosphate dehydrogenase with triazine dyes: a study by means of affinity partitioning and kinetic analysis.

The interaction of glucose-6-phosphate dehydrogenase (EC 1.1.1.

Description of a simple method to study some aspects of the pathogenesis of arteriosclerosis by perfusion of arterial segments.

A perfusion apparatus is described which permits the perfusion of arterial segments of about 5 cm in length. It works under physiological conditions. During the perfusion, temperature and pressure constancy or pressure variation, respectively, pulsation, sufficient oxygen supply, and high sterility are guaranteed.

Relationship between urea and ammonium excretion in the urine of very-low-birth-weight infants appropriate for gestational age.

In 14 very-low-birth-weight infants appropriate for gestational age the serum concentrations of urea and the excretions of urea and ammonium in the urine were studied on the 10th, 21st, and 42nd day of postnatal life. All infants were fed with a human milk preparation (6 g human milk lyophilisate per 100 ml fresh human milk). The enteral feeding could be started on the first day of life so that protein intakes were not different on the three study days (2.

Learning and retrieval are impaired after lesions of the ventral part of rat's nucleus reticularis pontis oralis.

Adult male hooded rats of the Long-Evans strain were investigated before and after lesions of the ventral nucleus reticularis pontis oralis (vRPO) in an open field test (OF) and in a Y-maze. The OF and the neurological findings were scarcely changed. Startle responses were strongly reduced and also horizontal head and body turning in the OF were significantly reduced.

Radial glial cells are present in the velum medullare of adult monkeys.

As a rule, in thin mammalian CNS tissues such as the median eminence and the retina, radial glia remains the dominating macroglia in adulthood, whereas in most other regions of the brain radial glial is substituted by multipolar macroglia i.e. astroglia.

Primary neurulation in teleosts--evidence for epithelial genesis of central nervous tissue as in other vertebrates.

Early teleostian embryos were studied by scanning electron microscopy. Transversal and longitudinal views of the neural anlage clearly demonstrate that it has an ordinary epithelial organization consisting of parallel columnar cells. Unless it has been supposed earlier, there is no solid thickened neural plate but the neural ectoderm is tightly folded forming a very narrow neural groove.

Ultrastructure of neurons and their synaptic contacts in the medial septal nucleus of the rat.

The medial septal nucleus of non-experimentally treated albino rats was investigated electron microscopically. According to former light microscopical findings most of the dendrites in this region are spineless but conspicuously varicose. Besides a striking diminution of the packing density of neurotubules inside the varicosities--compared with the narrow portions of varicose dendrites--some organelles like multivesicular bodies, lamellated bodies and cisterns of the smooth endoplasmic reticulum were found to be characteristic of them.

Determination of the extracellular tortuosity in nuclear layers of the central nervous system by resistance measurements on a geometrical model.

The electrical resistivity of nuclear layers within CNS tissues is simulated by a densely packed array of glass spherules with a thin silver layer on their surfaces. Various mean spherule diameters and different thicknesses of the silver layer are tested; the relations between spherule diameter and thickness of silver mantle are in the same range as those between cell soma diameters and width of the extracellular clefts. Measuring the contribution of the silver layers to the total volume--corresponding to the extracellular volume fraction alpha within CNS tissues--and the resistance of columns of silvered spherules, tortuosity factors lambda 2 are calculated.

Release of vasopressin and oxytocin by paraventricular stimulation in rats.

The nucleus tractus solitarius/dorsal motor nucleus of the vagus nerve (NTS/DMV) area was perfused by the push-pull perfusion technique in anesthetized rats, and perfusates were assayed for arginine vasopressin (AVP) and oxytocin (OXT) immunoreactivity. As compared with controls, electrical stimulation of the ipsilateral paraventricular nucleus (PVN) resulted in increased amounts of both AVP (approximately 5-fold) and OXT (approximately 10-fold, P less than 0.05 each) in the perfusates.

Purification and characterization of glucose-6-phosphate dehydrogenase from Pseudomonas W6.

Glucose-6-phosphate dehydrogenase (EC 1.1.1.

Synthesis and kinetic characterisation of omega-guanidinocarbonic acid ethyl esters as trypsin substrates.

Aliphatic omega-guanidinocarbonic acid ethyl esters of different chain length (C3-C6) were synthesized and characterized as 4-toluenesulfonates. The kinetic parameters of the trypsin-catalyzed hydrolysis indicate that the ethyl ester of delta-guanidinovaleric acid is the most effective substrate in this series. The Km value of this compound is in the same order of magnitude as those of arginine-containing ester substrates like N alpha-benzoylarginine ethyl ester (BAEE).

Lesions of median raphe nucleus disrupt active avoidance behaviour.

Active avoidance of eighteen adult male hooded rats was investigated in an Y-maze and a jump test before and after small symmetric lesions of the median raphe nucleus (n. centralis superior, CES). Formation of conditioned avoidance responses (CAR) was impossible without preoperative experience.

Active avoidance is permanently abolished after lesions of the nucleus interpeduncularis in rat.

Active avoidance learning, retention and relearning were investigated before and after lesions of the interpeduncular nucleus (IP) of rat in a Y-maze and a jump test box. Preoperatively learnt active avoidance was abolished after the lesions and rats were not able to relearn it. Unconditioned escape responses remained unchanged in the Y-maze.

Permanent changes of the visually evoked responses in the superior colliculus after early postnatal treatment with monosodium-L-glutamate.

10 rats of the Long-Evans strain were treated from the first to the eleventh postnatal day (pd) with daily subcutaneous injections of 4 mg/g body weight monosodium-L-glutamate (MSG) in aqua dest. 10 rats were used as controls and received isotonic NaCl-solution on the same days. When rats were 4 months old, electrodes were implanted in different depths of the superior colliculus (CS) to investigate averaged evoked potentials by flash (VEP) and by click stimuli (AEP).

Visually evoked responses in the primary cortex of rats are permanently changed by early postnatal treatment with monosodium-L-glutamate.

13 rats of the Long-Evans strain were treated from the first to the eleventh postnatal day (pd) with daily subcutaneous injections of 4 mg/g body weight monosodium-L-glutamate (MSG) in aqua dest. Further 13 rats were used as controls and received isotonic NaCl-solution on the same days. When rats were four months old, epidural electrodes were implanted on the visual cortex to investigate averaged evoked potential by flash (VEP) and by click stimuli (AEP).

Postnatal adaptation of lipase- and trypsin-activities in duodenal juice of premature infants appropriate for gestational age.

In 17 very low birth weight and in 13 low birth weight infants appropriate for gestational age the activities of pancreatic lipase and trypsin, the pH value and the concentrations of total bile acids were measured in the preprandially aspirated duodenal juice between the 10th and the 40th day of postnatal life. The activities of both enzymes increased significantly with increasing postnatal age in both study groups but did not correlate with the gestational age between the 28th and 33rd week of gestation. The pH values were on a low but similar level in both study groups (mean for all infants 5.

Modulating the microbial colonization of the gastrointestinal tract by oral administration of defined Escherichia coli strains. II. Influencing the biotope by means of geographically unrelated Escherichia coli strains.

An effective increase in the rate of colonization can be accomplished, in analogy with the pathogenetic mechanism of what is known as travelers' disease, through the administration of geographically unrelated strains. As compared to Escherichia coli strains isolated in the GDR, metabolic drift-optimized and Ethiopian strains showed an increase from 20 to 50%. It was not, however, possible to maintain a greater than or equal to 50% share in the population of Enterobacteriaceae over a period of more than up to three days.

Modulating the microbial colonization of the gastrointestinal tract by oral administration of defined Escherichia coli strains. I. Influencing the biotope by means of metabolic drift mutants of Escherichia coli.

Through the selection of spontaneous metabolic drift mutants (selection marker RifR) of an Escherichia coli strain (O6:H2 SmR) of known settling capacity in conventional mice, it was attempted to obtain clones with positively optimized in vitro characteristics, which may exert a promotive influence upon the in vivo colonizing behaviour. Using 512 drift mutant strains (E. coli O6:H2 SmR RifR) we were able to establish positive optimizations, at an over-aleatory rate, for each of the in vitro characters tested (haemagglutination capacity of rabbit, guinea pig, and fowl erythrocytes; overgrowing power of mouse-adapted wild-type E.

Histological examination of blood vessels in peripheral gangrene among patients with sporadic outbreak of ergotism.

During the academic year 1985-1986 at Gondar College of Medical Sciences Hospital gangrenous ergotism was clinically diagnosed in seven patients (5 males, 2 females) ranging in age from 20 to 45 years. Amputation and subsequent histological examination of the blood vessels revealed occluded tibial arteries by acute thrombosis without cellular reaction or inflammatory lesion of the arterial wall in 3 patients. Endangitis with organized arterial thrombosis and focal recanalization of the vessels was noted in the remaining four patients.

Different laminar distribution of flash evoked potentials in cortical areas 17 and 18 b of freely moving rats.

The laminar distribution of flash evoked field potential (VEP) was investigated in the visual cortical areas 17 and 18 b in freely moving rats. Averaged VEPs were recorded during stable relaxed wakefulness characterized behaviorally and polygraphically. The depth profiles of the main VEP components displayed polarity reversals in lamina V in every electrode track through area 17 while no polarity reversal was observed in any track through area 18 b.

Labyrinth learning impairment in patients with early symptoms of presenile dementia.

21 patients (54 +/- 7 years old) with early cognitive deficit (ECD) during the presenile stage of presumptive primary degenerative dementia (mild stage) and 14 patients (54 +/- 4 years old) with early cognitive deficit with a background of cardiovascular disease (CVD) were examined in a labyrinth learning test of Milner (modified by Roth). 15 patients in the ECD group made 3 times more errors to negative fields (p less than 0.01), about 10 times more errors to positive fields (p less than 0.