Spontaneous activity of single neurons in the olfactory bulb of the rainbow trout (Salmo gairdneri) and its modulation by olfactory stimulation with amino acids

Summary Spontaneous action potentials recorded from 126 neurons in the olfactory bulb of Salmo gairdneri show a higher tendency towards bursting patterns of activity than those shown in previous reports about other fish. Granule cells and periglomerular cells are more likely to fire in bursts than mitral cells. Natural chemical stimulation of the olfactory mucosa with amino acid solutions produced a unique pattern of excitatory and inhibitory responses across all units. Chi-square values were calculated for stimulatory effectiveness between forty-five pairs of odours. L-serine and L-alanine consistently showed a high degree of similarity with several other odours. The converse was true for GABA and L-histidine, although this pair had a high chi-square value when mutually compared. Enantiomeric pairs of amino acids were often found to have opposite stimulatory effects on bulbar units. These results are discussed in relation to the possible properties and configurations of odorant receptor sites for amino acids in the fish olfactory mucosa.     

Transport of urea and amino acids through the isolated human placenta

By means of a method of two-way perfusion of the isolated human placenta the transport of urea from the fetal to the maternal placental circulation and the transport of amino acids in the opposite direction were studied. Experiments showed that the method provides for sufficiently complete perfusion of the intervillous space and creates suitable conditions for the study of placental transport. If the amino nitrogen concentrations in the two circulatory systems are equal, its concentration in the fetal circulation rises in the course of the experiment. On the addition of an amino acid to the maternal circulation, this increase develops to a greater degree. The results of these experiments confirm the view that amino acids are secreted by trophoblast cells into the fetal circulation.Laboratory of Biochemistry, Institute of Obstetrics and Gynecology, Academy of Medical Sciences of the USSR, Leningrad. (Presented by Academician of the Academy of Medical Sciences of the USSR M. A. Petrov-Maslakov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 4, pp. 394–397, April, 1976     

Effect of basic amino acids on susceptibility to carbapenems in clinical Pseudomonas aeruginosa isolates

We evaluated effects of medium composition, including basic amino acid content and pH, on susceptibility to carbapenems such as imipenem, panipenem and meropenem, in clinical isolates of Pseudomonas aeruginosa. Susceptibility to carbapenems was reduced by basic amino acids in the medium, while susceptibilities to ceftazidime and aztreonam were not. Among carbapenems, susceptibility to panipenem was most sharply reduced by addition of basic amino acids to 1:16 Mueller-Hinton agar (MHA). In 174 of 175 clinical isolates, MICs for carbapenems were affected to different degrees by medium composition. One isolate, in which MICs for carbapenems did not differ between MHA and 1:16 MHA, showed reduced production of porin (OprD). Our results suggest that susceptibility to individual carbapenems, especially panipenem, is difficult to evaluate based on MICs for other carbapenems determined on MHA. For a better prediction of antibiotic efficacy, it may be important to evaluate the susceptibility for each carbapenem individually.     

O-acylated sialic acid variants in mucinous tumours of the ovary

Summary O-acylated sialic acid variants (site 8) can be demonstrated histochemically by the PB/KOH/PAS method. They are secreted by goblet cells of the lower gastrointestinal tract, by colorectal adenocarcinomas, and by their metastases. Since the metastases are positive only when the primary tumour is positive, O-acylated sialomucins can be considered to be specific markers of colorectal adenocarcinomas if identified in metastases of a tumour of unknown origin. In our histochemical study we evaluated 29 mucinous cystomas of the ovary (23 benign and 6 malignant). We found that six cases were positive to PB/KOH/PAS. The positivity was observed in a limited number of cells and only in areas which presented an intestinal type epithelium. It was also more evident in malignant cystomas than in benign ones. We therefore think that the PB/KOH/PAS positivity can not only be considered a marker of colorectal adenocarcinomas, but also of all neoplasms which originate from an intestinal epithelium or appear to an intestinal type epithelium.This work is partially supported by the M.P.I. (40%)     

Amino acid release from the cerebral cortex of the rabbit, its relationship with the electrocorticogram

The rate of release of five amino acids (alanine, glutamine, glutamic acid, glycine, GABA) from the surface of the sensorimotor cortex has been determined in rabbits under local anesthesia immobilized with gallamine. Concomitant recording of the electroencephalogram and of blood pressure has been carried out. The scope of the research was to determine if a difference in the release of these aminoacids could be correlated with variations in cerebral electrical activity. Two open-ended silver cylinders were adapted to the cortex and filled with saline. Every 10 min, the liquid was removed and assayed using a dansylating procedure followed by thin layer chromatographic separation and fluorimetric determination of the amino acids. The EEG of non treated animals, followed for a period of 100 min, remained synchronized for the majority of the recording; the biochemical determinations indicated a slight but constant fall in the rate of release of all the amino acids. A significant increase in the release accompanied the EEG desynchronisation induced either with eserine (0.2 mg/kg), amphetamine (2 mg/kg), or with electrical stimulation of the reticular formation.     

Effect of N-phthalamoyl-L-glutamic acid,a selective NMDA receptor agonist,on binding of3H-L-glutamate with hippocampal synaptic membranes

Institute of Experimental Medicine, Russian Academy of Medical Sciences, St. Petersburg. (Presented by Academician of the Russian Academy of Medical Sciences A. N. Klimov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 113, No. 6, pp. 563–565, June, 1992.     

Non-invasive amino acid turnover predicts human embryo developmental capacity

BACKGROUND: IVF is limited by low success rates and a confounding high multiple birth rate contributing to prematurity, increased neonatal mortality and child handicap. These problems could be overcome if single embryos of known developmental competence could be selected for transfer on day 2/3 of development, but current methods, which rely on morphological appearance, are poor predictors of viability. METHODS: We have measured non-invasively the depletion/appearance (i.e. turnover) of a physiological mixture of 18 amino acids by single human embryos during in-vitro culture using high performance liquid chromatography. RESULTS: From the time of transfer (day 2/3), embryos with future competence to develop to the blastocyst stage (day 5/6) exhibit amino acid flux patterns distinct from those of embryos with similar morphological appearance which arrest. Significantly, the profiles of Ala, Arg, Gln, Met and Asn flux predict blastocyst potentiality at >95%. The amino acid most consistently depleted throughout development by those embryos which form blastocysts was leucine. Of the amino acids which were produced, the most striking was alanine, which appeared in increasing amounts throughout development. CONCLUSIONS: Non-invasive amino acid profiling has the potential to select developmentally competent single embryos for transfer, thereby increasing the success rate and eliminating multiple births in IVF.     

Differential sensitivity of selected rat brain areas to excitatory neurotransmitters released by K+ depolarization

When injected intrathecally in mice in a volume of 5 microliter, adenosine had no effect on tail-flick or hot-plate reaction latencies at dosages up to 1 mM concentration. There were no other behavioral effects observed either. Injecting 1 mM of the adenosine receptor agonist, 5'-N-ethylcarboxamide adenosine (NECA) caused both motor paralysis of the hind-legs with a duration of approximately 4 h and simultaneous antinociception. A slight weakness of the hindlegs, but a profound antinociceptive effect, was observed after the 100 microM dose only. After 10 microM, there was no effect on motor behavior but still a prolongation of the tail-flick and hot-plate reaction latencies. Pretreatment with the adenosine receptor antagonist theophylline attenuated the antinociceptive effect of NECA. Activation of spinal adenosine receptors thus appears to selectively elicit analgesia.