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Biomedical subjects

M Hess

Publications and source records attributed to M Hess.

At least 181 records · Page 10Linked to original sources
PubMed1977

[Studies of the tolerance and toxicity of Luzern-green-meal pellets after selenium fertilization].

In a feeding trial, rabbits allotted in 3 experimental groups were fed rations containing 2.09, 9.83 and 19.5 mg selenium/kg feed in the form of selenium-enriched alfalfa green meal pellets. The selenium enrichment was done by foliar application (spraying) of the 20--25 cm high plant stand with 2.5 kg SeO2 per hectare in watery solution. The control animals were given normal alfalfa green meal pellets of 0.16 ppm selenium content. Toxicity and lethality, tolerance limit and nutritive effect of the pellets were studied. Plant-assimilated selenium was found to be converted more efficiently by the animal organism than was selenium from inorganic compounds (higher retention rate, better gain in body weight and lower feed expenditure). Therefore, the selenium supply to farm animals should be improved by feeding crops that were given selenium dressings.

Animal Feed↗
PubMed1976

Proestrous gonadotropin levels in thyroparathyroidectomized female rats.

Intact and TPTx animals showed the expected afternoon increase in serum LH,FSH and prolactin levels. But the afternoon increase in serum LH levels in TPTx rats was less than that observed for intact animals (p less than 0.001). Neither serum prolactin nor FSH levels were altered by TPTx.

Animals↗
PubMed1976

Immune response region-associated antigens of the mouse: biochemical properties of detergent and papain solubilized molecules.

Immune response region-associated (Ia) antigens and classical H-2 antigens are glycoproteins which differ in their molecular weight and tissue distribution. Ia and H-2 molecules also show differences in overall charge, apparent isoelectric point and susceptibility to proteolytic degradation, acid treatment and exposure to 56 degrees C. In the present paper, Ia.11d antigens were shown to have a molecular weight of about 35000 after solubilization with nonionic detergents. Purified Iad antigens, solubilized by controlled papain digestion, display a molecular weight of about 26000 after final purification by indirect immune coprecipitation. This figure corresponds to the molecular weight of a highly purified H-2 polypeptide fragment obtained after papain solubilization. The remarkable size similarity of proteolytic fragments from Ia and H-2 antigens could suggest that these genetically and functionally related molecules possess some structural features in common.

Animals↗
PubMed1976

Secondary cytotoxic allograft responses in vitro. III. The immunogenicity of allogeneic membrane fragments.

The immunogenicity of murine membrane fragments was tested both in primary and in secondary in vitro cytotoxic allograft responses, and compared to that of intact allogeneic stimulator cells. Allogeneic membrane fragments induced poor proliferative and cytotoxic responses in normal splenic responder cells. However reexposure of immune responder T cells to allogeneic membrane fragments triggered the generation of highly reactive cytotoxic T lymphocytes (CTL). Moreover, the generation of secondary CTL as induced by allogeneic membrane fragments was preceded by only a marginal cell proliferation. The results obtained are compatible with the concept that serologically defined (SD) antigens alone are capable of triggering alloimmune T cells to differentiate highly reactive secondary CTL.

Animals↗
PubMed1976

Ia antigens: isolation, chemical modification and structural characterization.

The results described above, with respect to the similarity of basic structural features of Ia and H-2 antigens (see Table V), led to the evolutionary concept presented in Figure 10 according to which these antigens are the products of tandem-duplicated genes. The evolution of MHC-gene products is reflected by the basic structure of these molecules. This structure is compatible with basic repetitive units of molecular weight 12,000 as suggested by the selective cleavage of the intact protein by, for example, papain.

Animals↗
PubMed1976

Effect of thyroidectomy on rhythmic gonadotropin release.

Nonstress blood samples were obtained from intact and thyroidectomized (TE) male rats at 3-hr intervals over a 24-hr period via rapid decapitation. The animals were thyroidectomized when 40 days old and used 6 weeks later. Intact animals showed periodicity in serum LH (P less than 0.01) and prolactin (P less than 0.01). Both gonadotropins began increasing after 8 PM and peak levels occurred at 11 PM. In contrast, 24-hr periodicity was not observed in serum FSH. Corticosterone levels in these same serum samples showed the expected circadian periodicity. After TE, the 24-hr pattern in all gonadotropins was altered significantly. Serum LH increased (P less than 0.01) and circadian periodicity appeared to be absent. FSH and prolactin levels were increased and decreased, respectively (P less than 0.01), with serum prolactin showing a 9-hr phase shift. Prolactin began increasing at 2 AM and reached a peak at 8 AM. Corticosterone in TE animals showed a 24-hr rhythm similar to that of intact rats. These findings confirm our previous observations that nonstress serum LH and prolactin levels fluctuate with a 24-hr periodicity and suggest that the level of, and the phase angle betweeen, these rhythms is markedly influenced by pituitary-thyroid activity.

Animals↗
PubMed1976

[LD50 values and selenium concentration in rabbit organs after parenteral administration of sodium selenite and determination of toxicity of urososelevit pro inj].

The LD50-values of sodium selenite after i/m injection to rabbits was determined by means of probit-regression straight line. Simultaneously a combination of vitamin E and sodium selenite was tested for toxicity in order to examine the effect of vitamin E on the selenium toxicity. The LD50/24h was 2.53 mg sodium selenite/kg body mass and in combination with vitamin E (30 IU vitamin E/5 mg NaSeO3) 2.73 mg/kg. Furthermore the selenium concentration was determined in blood, liver, kidney and muscles of animals which died or were killed after 24 h respectively. Not only chemical analysis but also relations of time-dose-efficiency and significantly increased LD50-values show a certain protective effect of vitamin E on selenium intoxication.

Animals↗
PubMed1976

[LD 50 and selenium concentration in the organs of rabbits following oral administration of sodium selenite and testing of the toxicity of Ursoselevit-Prämix].

LD50/24hr was established in the first of a series of experiments on 72 rabbits for orally applied sodium selenite. The dosage was 8.62 mg/kg live weight, the confidence interval being (1 - alpha = 0.95) +/- 0.13 mg/kg. The value was four times as high following intravenous application. Complete lethality was recorded from 15 mg Na2SeO3/kg live weight within 21 hours. Thirty-six animals were involved in the second experiment of the series. They had 50 or 100 per cent Ursoselevit-Prämix (30 ppm Se) in their rations. Body mass development of the test animals was superior to that recorded from the controls in the first 50 days, after which limit the former declined strongly in a few days. Their general condition worsened. Postmortem findings, following slaughter, included catarrhal enteritis, toxic liver dystrophy, scattered pulpous tumours in the spleen, and interstitial nephritis. In the third experiment (50 per cent Ursoselevit-Prämix with 60 ppm Se in the rations), the test animals developed better than the controls during the first two months, after which point they exhibited the same clinical symptoms as those observed in the second experiment, stopped to put on weight, and eventually turned cachectic. The pathomorphological findings were identical with those obtained from the second experiment. The selenium concentrations in the organs of the test animals all were much higher than those of the controls. Their amounts in excess to base values were up to eleven times in the blood, nine times in the liver, twelve times in the kidneys, and 13 times in the muscles.

Administration, Oral↗
PubMed1975

[LD 50 and selenium concentration in organs following intravenous administration of sodium selenite in the rabbit].

In experiments on 72 rabbits, the LD50 of sodium selenite by intravenous injection was found to be 2.24 mg/kg body weight. The clinical picture and pathological changes associated with acute selenium poisoning are described. The increase in selenium concentration was up to nine times the normal in liver and up to six times in kidney and muscle. There was no sign of a return to normal values 24 hours after administration.

Animals↗