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Biomedical subjects

A M Mayer

Publications and source records attributed to A M Mayer.

47 records · Page 3Linked to original sources
PubMed1977

Murine sarcoma virus pseudotypes used as immunogens against viral and chemical oncogenesis.

The purpose of this study was to develop an animal system of protective immunity against oncornaviruses and to test whether such immunization had an inhibitory effect upon chemical sarcomagenesis. Several murine sarcoma virus (MSV) pseudotypes were used as immunogens and tested against themselves, against other pseudotypes, against leukemogenesis by their helper viruses, and against sarcomagenesis by 3-methylcholanthrene. Five MSV pseudotypes were obtained by rescuing complete MSV from MSV-genome carrier, nonproducer hamster tumor cells, using five different leukemia viruses as helpers. The immunogenic properties of these pseudotypes could be specified on the basis of the following observations. 1) They all induced sarcomas in newborn mice and regressing sarcoma nodules in young adult mice. After regression, most mice remained free of neoplastic disease, but some developed sarcoma or leukemia relapses. 2) They had an individual host range pattern, usually determined by the helper virus, as tested by inoculation of a constant virus dose in BALB/c, C57BL/Ka, and Swiss mice. 3) They were all immunogenic, in the sense that the first virus inoculation prevented sarcoma induction by a second challenge, either viral or cellular. 4) They were cross-reactive in vivo, one pseudotype immunizing against another, in the combinations tested. 5) They were able to immunize against leukemogenesis induced by their helper viruses. This was shown by prevention of leukemic deaths by Rauscher and Friend viruses, by a slight prolongation of survival after challenge with the Precerutti-Law leukemia virus, and by inhibition of splenomegaly by Moloney leukemia virus. In a second stage of the study, we investigated whether immunization with any of the MSV psuedotypes had an inhibitory effect upon sarcomagenesis induced by near-threshold doses of 3-methylcholanthrene. The incidence of these sarcomas was essentially the same in virus-immunized and control mice. It was concluded that immunizing procedures able to prevent sarcomagenesis when the inducer is a virus did not have any consistent preventive effect when the inducer was a chemical.

Animals↗
PubMed1975

Changes in Catechol Oxidase and Permeability to Water in Seed Coats of Pisum elatius during Seed Development and Maturation.

In the developing seed coat of Pisum elatius, o-dihydroxyphenols are present in appreciable amounts at all stages of development. However, catechol oxidase activity rises sharply during the later stages of development, shows a further abrupt rise during dehydration of the seed coat, and then decreases. It is suggested that a tanning reaction is induced by the contact of enzyme with its substrate while cell membranes are ruptured, and that this reaction renders the seed coats impermeable. The entire chain of events does not occur in Pisum sativum which has permeable seed coats.

Journal Article↗
PubMed1974

Permeability of seed coats to water as related to drying conditions and metabolism of phenolics.

The seed coat of Pisum elatius is normally impermeable to water. When seeds are dried in the absence of oxygen their coats are totally permeable to water. Structural differences are observed between permeable and impermeable seed coats. In the genus Pisum, species with normally impermeable seed coats have a high content of phenolics and of catechol oxidase, while seed coats of P. sativum contain very little catechol oxidase and have a very low content of phenolics. Such differences are not noted in the cotyledons. We hypothesized that during dehydration of seeds, oxidation of phenolic compounds in seed coats through catalysis of catechol oxidase in presence of O(2) might render the seed coats impermeable to water.

Journal Article↗
PubMed1971

Permeation of dry seeds with chemicals: use of dichloromethane.

Dichloromethane can be used to introduce chemicals into dry seeds in the absence of water. The solvent has no effect on germination or respiration. The chemicals become effective when the seeds are placed in water under normal conditions for germination. The potential of the new method is discussed.

Acetone↗
PubMedDate not supplied

Diabetes care: a comparison of management systems.

During 1997, the Alaska Area Diabetes Program audited a sample of 837 charts from among the 1373 individuals receiving regular diabetes care at facilities serving predominantly American Indians/Alaska Natives. Charts were evaluated for the delivery of American Diabetes Association Standards of Care. Results of the audit showed a great deal of variability among facilities. Facilities which scored highly in the audit were more likely to use an organized multidisciplinary team approach that included coordinated clinic appointments with multiple providers on the same day, maintenance of a diabetes registry, proactive preclinic preparation, flow-sheet use, intensive individual nutritional counseling, a case manager or field clinic coordinator system with standing orders, and strong self-management support.

Alaska↗
PubMedDate not supplied

Marine pharmacology in 1999: antitumor and cytotoxic compounds.

During 1999 marine antitumor pharmacology research involved researchers in Austria, Australia, England, France, Germany, Greece, Holland, Italy, Japan, Spain, Taiwan and the United States. Thirty six papers were published in peer-reviewed journals describing the antitumor and cytotoxic properties of 30 marine natural products belonging to four structural types, namely polyketides, terpenes, nitrogen-containing compounds and polysaccharides. The organisms yielding these bioactive marine compounds comprised a diverse group of marine animals, algae, fungi and bacteria. A variety of antitumor pharmacological studies were conducted with 17 marine natural products with established mechanisms of action in a number of experimental and clinical models. Didemnin B, a tunicate-derived depsipeptide with potent antitumor effects, completed a Phase II anticancer clinical trial which resulted indeterminate in respect to activity against human melanoma due to anaphylactoid reactions. In vitro cytotoxicity data with murine and human cell lines were reported for 14 novel marine chemicals with as yet undetermined mechanisms of action. This 1999 literature overview thus highlights the fact that the multinational effort aimed at the discovery of novel marine antitumor agents remained at the same level of research activity as during 1998.

Animals↗