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Biomedical subjects

H Simon

Publications and source records attributed to H Simon.

At least 253 records · Page 14Linked to original sources
PubMed1981

The reduction of allyl alcohols by Clostridium species is catalyzed by the combined action of alcohol dehydrogenase and enoate reductase.

Cells, as well as crude extracts of Clostridium kluyveri or Clostridium spec. La 1, catalyze the hydrogenation of (E)- or (Z)-2-butenol to n-butanol. No single enzyme could be detected which directly accomplishes this reaction. It turned out that the reduction occurs as follows: 2-butenol leads to 2-butenal leads to n-butanal leads to n-butanol. The first step is catalyzed by the NAD-dependent alcohol dehydrogenase in C. kluyveri, the second by the recently detected enoate reductase which reduces not only nonactivated alpha, beta-unsaturated acylates but also alpha, beta-unsaturated aldehydes in a NADH-dependent reaction and the third step is again catalyzed by alcohol dehydrogenase. In Clostridium La 1 the alcohol dehydrogenase is NADP-dependent. The rate of the reduction of 2-butenol to n-butanol depends not only on the enzymes, but also on the ratio NAD(P)/NAD(P)H. In the presence of methylviologen cation radical which is formed by the reduction of methylviologen by the system H2/hydrogenase, the ratio NAD(P)/NAD(P)H is too small for the dehydrogenation of 2-butenol to 2-butenal. This explains the antagonistic effect of methylviologen in the hydrogenation of allyl alcohols and 2-enoates by both Clostridium species. Furthermore, the mechanism explains the finding that from a preparative point of view ethanol is a better electron donor than hydrogen for the stereospecific reduction of allyl alcohols.

1-Propanol↗
PubMed1981

[Histological, electron microscopical and X-ray microanalytical findings in malakoplakia of the kidney (author's transl)].

Malakoplakia which was found in the kidney if a man aged 55 years is described. This rare granulomatous lesion was extirpated together with a renal cyst. So-called Hansemann-cells with inclusion bodies and ring structures were found by light and electronmicroscopic examinations. These concentrically arranged ring like structures were not typical Michaelis-Gutmann-bodies, and they consisted of microfibrils and small granula. Using X-ray microprobe analysis could be detected calcium. These findings were considered to be an early stage of malakoplakia.

Calcium↗
PubMed1981

[Dopaminergic A10 neurons and frontal system (author's transl)].

Lesions in the rat of the ventral mesencephalic tegmentum (vmt) which contains the A10 dopaminergic (DA) cell bodies, have a wide range of effects on behaviour. The principal characteristic of such lesioned animals is a locomotor hyperactivity and a disinhibition of behavioural supression with serious consequences for behaviour fundamental to the survival of the individual and the species. 1 Initially, we felt that an anatomical study of the region could provide a basis for explaining the vmt syndrome. We decided, therefore, to use several anatomical techniques, such as silver staining, anterograde tracing using autoradiography, and retrograde tracing with horseradish peroxidase (HRP). These studies have led to the following conclusions: (1) The vmt neurones are an important interface between anterior limbic structures and posterior limbic and reticular regions. (2) vmt neurones have specific anatomical relations with the frontal system, i.e., the prefrontal cortex and the anterior striatum. 2 Secondly, we wondered if such anatomical connections were the basis for functional relationships. We have therefore studied animals in a delayed alternation task, which is a sensitive and selective test of damage to the frontal system. Rats with electrolytic or 6-hydroxydopamine (6-OHDA) lesions of the DA cells in the vmt show large deficits in delayed alternation tasks. 6-OHDA lesions of the DA A10 terminals in the prefrontal cortex, the anterior striatum or the nucleus accumbens lead to similar behavioural deficits. Moreover, the specificity of such deficits has been shown in a runway test and a visual discrimination task. 3 On the basis of these results, we put forward the hypothesis that the A10 DA neurones play a role in the integration of information from internal and external stimuli which are relayed to the prefrontal system. From this viewpoint, a deficit in selective attention lies at the heart of the different forms of the vmt syndrome.

Animals↗
PubMed1981

Logical classifiers for image analysis in medicine.

A simple, intuitive procedure for the stepwise classification of objects in n-dimensional feature spaces is presented. Each classification step is based on a single feature decision and provides an optimal separation of the objects of only one class from the objects of all other classes. The algorithm of this procedure is implemented on a minicomputer of an image-analysis system. Testing of the classifiers on biomedical data (213 slides of diseased and normal liver tissue) yielded good results requiring few decisions and threshold parameters: 152 correct classifications, 16 incorrect classifications and 45 rejections.

Cell Nucleus↗
PubMed1981

[Gastric carcinoma; pathology (author's transl)].

Frequency, macro- and microanatomy, and propagation routes of gastric cancer are outlined. Early carcinoma is discussed and the relation of gastric mucosal polypi to carcinoma of the stomach. Finally the significance of biopsies and the possibility of its misinterpretation are stressed.

Adenocarcinoma↗
PubMed1980

[Effects of lesions of the anterior raphe nuclei on the self-administration of d-amphetamine in the rat : considerable increase of desire for the poison].

The acquisition of the intravenous self-administration of d-amphetamine was studied after separate lesions of anterior raphe nuclei (dorsal or median). Every lever-press delivered 2.5 microliter of a d-amphetamine solution dosed at 7.5 microgram/kg. Lesion of anterior raphe nuclei produced an hyper-sensitivity to d-amphetamine as indicated by a dramatic increase in self-administration by experimental Rats compared to the controls. Moreover this enhanced self-administration behavior is observed with a low blood concentration of d-amphetamine. The greater increase was obtained for median raphe lesioned Rats. These effects are interpreted in terms of 5HT-DA balance and could provide an experimental model for neurobiological bases of drug addiction studies.

Animals↗
PubMed1980

Utilization of (E)-2-butenoate (crotonate) by Clostridium kluyveri and some other Clostridium species.

Clostridium La 1 obtained from a Clostridium kluyveri culture was compared with a typical C. kluyvery strain (DSM 555). The former grows on cortonate and is unable to use ethanol-acetate as carbon sources. The latter grows on crotonate only after long adaptation periods. Resting cells of both strains show also pronounced differences in the fermentation of crotonate. This holds even for C. kluyveri grown on crotonate. Besides several other differences the most striking is that there is no hybridization between the DNA of both strains. Crotonate seems not to be a very special carbon source since C. butyricum and C. pasteurianum grow on crotonate medium supplemented by peptone and yeast extract.

Acetates↗
PubMed1980

[The extracorporeal blood glucose regulation in the pancreatectomised dog (author's transl)].

An algorithm is demonstrated which runs by means of program internal decision schedules for insulin applications during the extracorporeal blood glucose regulation by the artificial endocrine pancreas. This algorithm defines clear conditions for the regulation of the insulin pump considering the actual blood glucose concentration and its speed of change. It is easy to modify and hence feasible under different conditions.

Animals↗
PubMed1980

Origin of dopaminergic innervation of the rat hippocampal formation.

The origin of the dopaminergic afferents to the rat hippocampal formation has been investigated by measuring dopamine and DOPAC contents in this area after electrolytic or chemical lesion of the ventral tegmental area (A10) or substantia nigra (A9). The present study indicates that dopaminergic afferents to the hippocampal formation originate from the A10 and A9 dopaminergic cell groups. The 'anterior' hippocampal formation receives a major input from the A10 area whereas the 'posterior' hippocampal region receives dopaminergic afferents from both A9 and A10 cell groups. The dopaminergic afferents are entering the hippocampal region mainly through the dorsal route.

3,4-Dihydroxyphenylacetic Acid↗