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Biomedical subjects

J Metz

Publications and source records attributed to J Metz.

At least 127 records · Page 7Linked to original sources
PubMed1984

Neurons of the A1/A2 region in the guinea pig medulla oblongata containing glucagon, glicentin, and dopamine-beta-hydroxylase immunoreactivity.

Glucagon- (GLU-IR), glicentin- (GLI-IR) and dopamine-beta-hydroxylase (DBH-IR) immunoreactive neurons were mapped in the medulla oblongata of colchicine pretreated guinea pigs. Numerous GLU-IR and GLI-IR perikarya are located in the area of the nucleus ambiguus, in the adjacent formatio reticularis, and less frequently in the nucleus reticularis lateralis, the nuclei raphe obscurus and commissuralis and the caudal part of the nucleus solitarius. In these nuclei, the coexistence of glicentin and glucagon within the same perikarya is demonstrated. DBH-IR is also found in neurons of the nuclei commissuralis, solitarius and reticularis lateralis (A1/A2 system of Dahlström and Fuxe 1964, 1965). However, a coexistence of GLU/GLI-IR and DBH-IR within the same neuron is not observed.

Animals↗
PubMed1984

Immunohistochemical localization of cardiodilatin in myoendocrine cells of the cardiac atria.

Region-specific antibodies against synthetic N-terminal fragments of cardiodilatin (CDD) were raised in rabbits and used for the immunohistochemical detection of this new peptide hormone in the myoendocrine cells within the cardiac atria of several species. The peroxidase-antiperoxidase (PAP) and fluorescein isothiocyanate (FITC) immunohistochemical methods gave identical results of cardiodilatin-immunoreactivity (CDD-IR) within the tissue. In addition to the porcine right atrial appendage, myoendocrine cells with CDD-IR were also detected in the left atrium of porcine heart, as well as in other species such as dog and cat. The exact localization of the immunoreactivity in specific secretory granules was mostly related to the Golgi-area which is located on both nuclear poles of auricular myoendocrine cells. The results confirm that cardiodilatin is stored in secretory granules observed through electron microscopical means. This hormone is most likely synthesized and released in myoendocrine cells, exerting its important cardiovascular effects.

Animals↗
PubMed1984

Distribution of NT-IR perikarya in the brain of the guinea pig with special reference to cardiovascular centers in the medulla oblongata.

The occurrence and distribution of neurotensin-immunoreactive (NT-IR) perikarya was studied in the central nervous system of the guinea pig using a newly raised antibody (KN 1). Numerous NT-IR perikarya were found in the nuclei amygdaloidei, nuclei septi interventriculare, hypothalamus, nucleus parafascicularis thalami, substantia grisea centralis mesencephali, ventral medulla oblongata, nucleus solitarius and spinal cord. The distribution of NT-IR perikarya was similar to that previously described in the rat and monkey. In the gyrus cinguli, hippocampus and nucleus olfactorius, though, no NT-IR neurons were detected in this investigation. Additional immunoreactive perikarya, however, were observed in areas of the ventral medulla oblongata, namely in the nucleus paragigantocellularis, nucleus retrofacialis and nucleus raphe obscurus. The relevance of the NT-IR perikarya within the ventral medulla oblongata is discussed with respect to other neuropeptides, which are found in this area, and to cardiovascular regulation.

Animals↗
PubMed1984

Transition from a hunter-gatherer to a settled lifestyle in the !Kung San: effect on iron, folate, and vitamin B12 nutrition.

In 1969 a group of hunter-gatherer San were studied (Am J Clin Nutr 1971;24:229-42). Their state of hematological nutrition was excellent with a negligible incidence of iron, folate, or vitamin B12 deficiency. A genetically and linguistically similar San community who have been settled for the past 15 yr were the subjects of the present study. Anemia, due in the main to iron and/or folate deficiency, has become more common. Alcoholism has become rife in both sexes and all age groups. Our findings show that a settled lifestyle has resulted in a significant deterioration in the San's hematological nutrition.

Adolescent↗
PubMed1984

Betaine delays the onset of neurological impairment in nitrous oxide-induced vitamin B-12 deficiency in fruit bats.

The mechanism whereby vitamin B-12 deficiency leads to neurological changes in humans is still uncertain. Nitrous oxide (N2O), which inactivates vitamin B-12 in vivo, results in neurological impairment leading to ataxia and death in the fruit bat Rousettus . These changes were prevented by the injection of the vitamin. The effect of dietary betaine (a catalytic product of choline) or methionine supplementation was studied in bats exposed to N2O. Supplementation with betaine resulted in less weight loss and delayed onset of neurological impairment when compared with unsupplemented animals. Supplementation with methionine at similar concentrations (600 mg/kg fruit and 2 g/kg fruit) was more effective in preventing weight loss and delaying the onset of neurological impairment than the corresponding levels of betaine. These results suggest that dietary betaine was effective in increasing that part of methionine synthesis that is not dependent on vitamin B-12 in N2O-exposed bats with impairment of the vitamin B-12-dependent methionine synthase reaction.

Animals↗
PubMed1984

Biological studies of schizoaffective disorders.

Biological studies of the relationships between the schizoaffective disorders, the affective disorders, and schizophrenia suggest that no simple reductionist model is supported by currently available data. Thus, both affective and schizoaffective patients but not schizophrenics, manifest abnormalities such as decreased platelet serotonin (5-HT) uptake, blunted clonidine-induced increase in serum growth hormone, shortened latency of rapid eye movement (REM) sleep, and increased REM density. However, there are some types of studies which show greater similarity between schizoaffective and schizophrenic patients than between schizoaffectives and affectives--e.g., increased cerebrospinal fluid (CSF) norepinephrine levels, increased platelet 5-HT content, and decreased prostaglandin E1-stimulated adenylate cyclase activity. Other types of studies show abnormalities common to all three groups of psychoses--e.g., eye tracking dysfunction, elevated CSF concentration of gamma-aminobutyric acid, and neuromuscular abnormalities. There are also abnormalities that have been reported to be present in only one type of the psychoses. Although none of these findings have been so unequivocally demonstrated that they can be considered to be firmly established, they do suggest that it is premature to conclude that the schizoaffective disorders are subtypes of the affective disorders. The possibility of a continuum model of the psychiatric psychoses of unknown etiology merits further consideration. Further biological studies of a broad range of psychiatric psychoses with inclusion of the schizoaffective categories appear indicated.

Blood Platelets↗
PubMed1984

The deoxyuridine suppression test.

The deoxyuridine suppression (dU) test, first described in 1964, has gained an important place both in the diagnosis of megaloblastic anemias and in the study of vitamin B12 folate interrelationships in the pathogenesis of megaloblastic anemia. The test measures the integrity of the de novo synthetic pathway of DNA synthesis, in which vitamin B12 and folate play an essential role. The exact mechanism of the test is still largely unknown. However, it is probably the most sensitive and specific functional test for the establishment of vitamin B12 and/or folate deficiency. As such, it is an important diagnostic tool in the investigation of patients suspected of suffering from deficiency of either or both of these vitamins. The test may also have applications towards the study of other factors required for the de novo synthesis of DNA.

Alcoholism↗
PubMed1984

Urinary thiamine excretion after oral physiological doses of the vitamin.

Urinary thiamine excretion has been measured in healthy subjects after oral physiological doses of the vitamin. There was a highly significant correlation between the oral dose and the urinary excretion. However, there was considerable overlap between the baseline values and the urinary excretion following doses up to 1000 micrograms. It is recommended that repeated daily measurements are made to differentiate baseline excretion from that recorded after oral physiological doses. This study may have relevance to the monitoring of dietary fortification programmes with thiamine.

Adult↗
PubMed1983

Acceptability trials of maize meal fortified with niacin, riboflavin and folic acid.

In Western countries two common and successful measures employed to combat nutritional deficiencies and deficiency diseases are: (i) enrichment of refined cereal products with nutrients lost during milling; and (ii) fortification of common foodstuffs with nutrients the intake of which in the general population is regarded as inadequate. In South Africa in 1978 a committee appointed by the Medical Research Council urged that because of the nutritional situation, particularly among the Black population and more especially relating to pellagra, niacin, riboflavin and folic acid should be added to the staple maize meal. Accordingly, investigations have been undertaken to assess the ability of Blacks to discriminate between fortified and non-fortified maize meals. Studies on groups of adolescents and adults revealed that this ability is not significant, indicating that no problem should be encountered as regards the general acceptability of the fortified product. These findings are in agreement with acceptance by the public overseas of enriched bread and 'corn' products where the latter have been introduced. There is therefore no reason why the milling industry should delay the fortification of all maize meal produced for human consumption.

Adolescent↗
PubMed1983

The right auricle of the heart is an endocrine organ. Cardiodilatin as a peptide hormone candidate.

A new polypeptide hormone candidate regulating vascular smooth muscle function was extracted from porcine atrial tissue. The purification steps were followed by a bioassay. The hormonally active substance has been analyzed and found to be a small polypeptide exhibiting a molecular weight of about 7500 and is named "cardiodilatin" (CDD). Further chemical data on this new hormone will be published elsewhere. A partial amino acid sequence of cardiodilatin is offered and shows that among the well known hormones or neuropeptides, none exhibit a homologue partial sequence.

Amino Acid Sequence↗
PubMed1983

Tissue S-adenosylmethionine levels in fruit bats (Rousettus aegyptiacus) with nitrous oxide-induced neuropathy.

The effect of cobalamin inactivation by the anaesthetic gas nitrous oxide on the concentration of S-adenosylmethionine (Ado Met) in brain and liver of fruit bats (Rousettus aegyptiacus) was examined. Test animals exposed to N2O-oxygen (50:50, v/v) developed ataxia and paralysis leading to death after an average of 9.8 weeks (n6). Animals receiving pteroylmonoglutamic acid supplements in the diet became ataxic earlier (mean 8.8 weeks) while those receiving methionine supplements survived for significantly longer periods (12.5 weeks, P less than 0.01). Plasma cobalamin levels indicated severe depletion of cobalamin stores in N2O-exposed animals. The mean concentration of Ado Met in the brain of N2O-treated bats was nearly 50% higher than that of untreated controls. Ado Met levels in treated bats receiving pteroylmonoglutamic acid or methionine supplements were respectively 18 and 25% higher than in controls. In contrast, the concentration of Ado Met in the liver of all the N2O-treated groups was slightly lower than in controls. These results suggest that the N2O-induced neuropathy in the fruit bat is not related to a depletion of Ado Met in the nervous system.

Animals↗
PubMed1983

Effect of a vitamin B-12-deficient diet on lipid and fatty acid composition of spinal cord myelin in the fruit bat.

The effects of vitamin B-12 deficiency on lipids and fatty acids of spinal cord myelin were studied in control and vitamin B-12-deficient fruit bats. Very low plasma and brain vitamin B-12 concentrations were present in animals fed the vitamin B-12-free, all fruit diet. Myelin was isolated from the spinal cord of control and vitamin B-12-deficient animals (n = 3 pools) by means of a flotation method in a discontinuous sucrose gradient. The molar concentration of cholineglycerophosphatide was significantly lower in the deficient bats than in the controls. The molar cholesterol: phospholipid ratio in the deficient bats was also significantly lower. The odd-chain fatty acid 15:1 was not detected in cholineglycerophosphatide from the controls, but comprised 1.4% of the total fatty acids in the deficient group. The odd-chain fatty acids 15:0, 17:1 and 19:0 were present in slightly higher amounts in cholineglycerophosphatide of deficient bats. Lipid and fatty acid differences were related to the vitamin B-12-requiring methionine synthetase and methylmalonyl CoA mutase reactions.

Animals↗
PubMed1982

Cobalamin inactivation by nitrous oxide produces severe neurological impairment in fruit bats : protection by methionine and aggravation by folates.

Nitrous oxide, which inactivates cobalamin when administered to fruit bats, results in severe neurological impairment leading to ataxia, paralysis and death. This occurs after about 6 weeks in animals depleted of cobalamin by dietary restriction, and after about 10 weeks in cobalamin replete bats. Supplementation of the diet with pteroylglutamic acid caused acceleration of the neurological impairment - the first unequivocal demonstration of aggravation of the neurological lesion in cobalamin deficiency by pteroylglutamic acid. The administration of formyltetrahydropteroylglutamic acid produced similar aggravation of the neurological lesion. Supplementation of the diet with methionine protected the bats from neurological impairment, but failed to prevent death. Methionine supplementation protected against the exacerbating effect of folate, preventing the development of neurological changes. These findings lend support to the hypothesis that the neurological lesion in cobalamin deficiency may be related to a deficiency in the methyl donor S-adenosylmethionine which follows diminished synthesis of methionine.

Animals↗
PubMed1982

Effect of chlorpromazine on H-reflex recovery curves in normal subjects and schizophrenic patients.

This study sought to determine the effect of chlorpromazine (CPZ) on a physiological measure, the H-reflex recovery curve (HRRC) and to determine whether the effect is different in normal subjects and schizophrenic patients. Eleven normal control subjects and 14 patients were administered 12.5 and 25.0 mg CPZ by IM injection. On the average. HRRCs measured 90 min after the injections were lower compared to pre-injection levels in both groups, at both doses. In general, the higher dose was more effective in both groups. Half of the patients, however, failed to respond to 12.5 mg, indicating that some schizophrenics are less sensitive than normals to CPZ. These results indicate that excessive dopamine activity or sensitivity may underlie abnormally high HRRCs in unmedicated psychotic patients.

Adolescent↗
PubMed1982

A comparison of serum transcobalamin levels in white and black subjects.

Serum transcobalamins (TC) have been measured in 82 white and 79 Black healthy adults, 170 white and 73 Black pregnant subjects and in cord blood samples from 33 whites and 13 Blacks. Healthy Black adults had significantly higher mean TC I, TC II, and TC III levels than white adults of the same sex. These differences in mean TC levels persisted at all stages of pregnancy. Mean cord blood levels of TC II and TC III were significantly higher in Blacks than in whites. No environmental factors could be identified to account for these differences, which are probably genetically determined.

Adult↗