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Biomedical subjects

A Metz

Publications and source records attributed to A Metz.

18 recordsLinked to original sources
PubMed1991

Stress--mechanisms of immunosuppression.

Stress, a term commonly used to describe varied phenomena, should be restricted to describe an adaptive response by an animal to threats to homeostasis. The threats to homeostasis are called stressors. Stressors include a variety of physical, psychological, chemical, or infectious causes that are modified by intrinsic and extrinsic factors. Examples of modifiers include stressor severity, duration, novelty, host genetics and immune status. What may be a stressor to an animal in one situation, when modified, may not be a stressor in another situation. Mechanisms of stress once thought to involve a single pathway described by Seyle as the General Adaptation Syndrome, have been rejected. Four pathways, some incompletely defined, have been implicated in modulation of the immune system. They include autonomic nervous system, the hypothalamic adrenal axis, extra-adrenal pathways involving neuropeptides and neurotransmitters and neuroimmunological mediators. The mechanisms of stress-induced immunosuppression resistance are poorly defined in domestic fowl and will require careful experimentation linking defined stressors with altered physiological responses that affect specific immune function and result in increased disease susceptibility.

Adaptation, Physiological↗
PubMed1986

The effects of the GABA-mimetic drugs, progabide and baclofen, on the biochemistry and function of 5-hydroxytryptamine and noradrenaline.

Administration to mice of a single dose of (+/-)-baclofen (5 mg/kg) or progabide (100 mg/kg) significantly inhibited the head-twitch response mediated by 5-hydroxytryptamine (5-HT2) receptors 30 min (but not 3 hr) later, when the response was produced by injection of carbidopa (25 mg/kg) plus 5-hydroxytryptophan (5-HTP; 100 mg/kg). No change was seen in the head-twitch response when induced at this time by 5-methoxy-N,N-dimethyltryptamine (5-MeODMT; 5 mg/kg). Inhibition of the head-twitch response after injection of 5-HTP was produced by pretreatment with (-)-baclofen, but not (+)-baclofen; injection of (+)-baclofen with the (-)-baclofen did not alter the attenuation of the behaviour produced by the active isomer. Twenty-four hours after the last injection of progabide, given repeatedly (100 mg/kg injected 5 times over 10 days) specific binding of [3H]ketanserin in the frontal cortex was enhanced and the head-twitch response to both 5-HTP and 5-MeODMT was markedly increased. The sedation response mediated by alpha 2-adrenoceptors, which followed the injection of clonidine (0.25 mg/kg) was attenuated. Repeated administration of baclofen (10 mg/kg per day in drinking water) also increased the number of 5-HT2 receptors in the frontal cortex (16%) and enhanced the head-twitch behaviour after injection 5-HTP or 5-MeODMT. Clonidine-induced sedation, number of beta-adrenoceptors in the cortex and apomorphine-induced locomotor activity were all unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1978

[Behavior of total serum cholesterol in aging rats in relation to food intake, weight development and mortality rate].

Rats (OFA - Sandoz) were kept under barrier conditions their whole lives in order to study the correlations between food intake, body weight, serum cholesterol and mortality rate. The cholesterol levels in males in the first life-half rose in correlation to food intake and body weight increase. In the second half, however, the cholesterol level increased again, whereas body weight and food intake decreased. The mortality rate rose, which was correlated to the second increase of the cholesterol level and the body weight loss (probit analysis). These findings were not made in females, which had lower food intake, body weight and cholesterol levels.

Aging↗
PubMed1977

Influence of 4'-6'-diamidino-2-phenylindole on the secondary structure and template activities of DNA and polydeoxynucleotides.

The interaction between 4'-6-Diamidino-2-Phenylindole-hydrochloride (DAPI) and a variety of DNAs and synthetic polydeoxynucleotides was investigated in order to delineate the nucleic acid structural features necessary for binding. The spectra of DAPI-DNA complexes, measured at various DAPI:DNA molar ratios (r), are hypochromic relative to DNA in the region of its maximum absorption. All the curves pass through an isosbestic point at 268 nm. A new maxima appears in the region of 380-392 nm for DAPI-DNA COMplexes. The magnitude of the peaks in the region are directly proportional to the amount of drug present in the complex. Studies with various DNA types and synthetic polydeoxynucleotides indicate that the drug preferentially binds to dAT-rich regions of DNA. This was also confirmed by enzymatic studies. The inhibition of template action by DAPI in a purified DNA-polymerase reaction was dependent on the dAT-content of the template. The implication of these data to explain a selective binding of DAPI to mitochondrial DNA have been discussed.

Amidines↗
PubMed1976

The effects of the beta-adrenoceptor blocking agent LL 21-945 on renal hypertensive (Grollman) rats.

Prophylactic administration of LL 21-945 [4-(3-tert. butyl-amino-2-pivaloyloxypropoxy)-9-fluorenone] during 15 weeks to Grollman rats depressed the development of hypertension, tachycardia and myocardial pathogical changes. The tachycardia was eliminated and the degree of the myocardial pathological changes and coronary sclerosis was less severe than in the untreated Grollman rats. The survival rate was slightly improved with LL 21-945. With respect to the biochemical parameters studied, only a tendency of LL 21-945 to moderate the rises in blood cholesterol, total glycerides and urea was observed towards the end of the experiment.

Adrenergic beta-Antagonists↗
PubMed1975

[A comparative study of total protein and albumin in man, monkey, dog and rat employing different analytical methods (author's transl)].

In the present study, serum albumin was determined colorimetrically in three animal species and in man with the help of four currently used dye-reagents (protein binding reagents). The results were compared with those obtained from corresponding electrophoretic and biuret determinations, using Versatol as a standard-control throughout. Using 2-(4-hydroxyazobenzene)-benzoic acid and bromocresol purple as reagent for the albumin determinations, species-specific differences from the electrophoretic results were found. No such differences occurred with bromo-cresol green, except in rats. There was no significant difference in albumin concentrations between man, monkeys and rats. Total protein concentration was only similar in man and monkeys.

Animals↗