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M Altmann

Publications and source records attributed to M Altmann.

63 records · Page 4Linked to original sources
PubMed1988

Sociometrics of Macaca mulatta: II. Decoupling centrality and dominance in rhesus monkey social networks.

The concept of the linear dominance hierarchy and a much less precise notion of a central/peripheral ordering of individuals have been prominent among the ideas about social organization of monkey groups. Although the latter has seldom been quantified, the ranks of individuals in the two orders are usually assumed to be correlated. This paper reports on a longitudinal study of a free-ranging group of rhesus monkeys. The individual histories of progression of dominance rank and an independently determined measure of centrality in the social grooming network are compared among a set of males. Centrality is not a static correlate of dominance rank as implied by the findings of short-term studies. Rather, centrality is a more sensitive indicator of status than is dominance rank, to which it is related in a dynamic fashion. Small changes in dominance rank may be followed by large changes in centrality. An increase in centrality may facilitate rise in dominance rank. These findings suggest a complex psychology of status, rather than a simple causative relation between the two variables.

Animals↗
PubMed1987

mRNA cap-binding protein: cloning of the gene encoding protein synthesis initiation factor eIF-4E from Saccharomyces cerevisiae.

We have isolated genomic and cDNA clones encoding protein synthesis initiation factor eIF-4E (mRNA cap-binding protein) of the yeast Saccharomyces cerevisiae. Their identity was established by expression of a cDNA in Escherichia coli. This cDNA encodes a protein indistinguishable from purified eIF-4E in terms of molecular weight, binding to and elution from m7GDP-agarose affinity columns, and proteolytic peptide pattern. The eIF-4E gene was isolated by hybridization of cDNA to clones of a yeast genomic library. The gene lacks introns, is present in one copy per haploid genome, and encodes a protein of 213 amino acid residues. Gene disruption experiments showed that the gene is essential for growth.

Base Sequence↗
PubMed1985

Purification and characterization of protein synthesis initiation factor eIF-4E from the yeast Saccharomyces cerevisiae.

A 24 000-dalton protein [yeast eukaryotic initiation factor 4E (eIF-4E)] was purified from yeast Saccharomyces cerevisiae postribosomal supernatant by m7GDP-agarose affinity chromatography. The protein behaves very similarly to mammalian protein synthesis initiation factor eIF-4E with respect to binding to and elution from m7GDP-agarose columns and cross-linking to oxidized reovirus mRNA cap structures. Yeast eIF-4E is required for translation as shown by the strong and specific inhibition of cell-free translation in a yeast extract by a monoclonal antibody directed against yeast eIF-4E.

Animals↗
PubMed1984

Chemically induced differentiation of murine embryonal carcinoma in vivo: transplantation of differentiated tumors.

Murine embryonal carcinoma tumors were induced to differentiate in vivo by administration of retinoic acid. Six long-term surviving animals had seven slowly growing tumors which were transplanted s.c. into strain 129 mice. Untreated embryonal carcinomas were transplanted as controls. All of the 16 control transplants grew rapidly and killed their hosts within 25 days. All of the 24 transplants of retinoic acid-differentiated tumor survived. Sixteen experimental transplants originating from five original tumors showed no or slow growth for up to 16 weeks and were found to be histologically benign cystic teratomas. Two original tumors gave rise to eight relatively rapidly growing transplants. One tumor resulted in four histologically similar solid tumors which resembled chondrosarcomas, and the second tumor gave rise to four histologically similar solid tumors which proved to be a mixture of glioma and chondrosarcoma. Examination of the tumor sources of these latter transplants showed benign cystic teratomas with focal solid, mitotically active cellular areas which were histologically similar to the transplants. These data confirm that retinoic acid-induced differentiation of murine embryonal carcinoma cells results in altered biological potential of these cells and usually the formation of a benign teratoma. Rarely (about 1 per 2 X 10(8], the resulting differentiated cells will give rise to rapidly growing, histologically malignant tumors. One can predict such biological propensity when solid, mitotically active areas in the original tumor are found.

Animals↗
PubMed1984

Malignant neoplasms of differentiated cells occurring after retinoic acid treatment of murine embryonal carcinomas in vivo.

Murine embryonal carcinoma tumors were induced to differentiate in vivo using retinoic acid. Six mice bearing seven tumors survived more than 100 days after treatment. Histological samples of these tumors showed no residual embryonal carcinoma cells, and, for the most part, they were benign cystic teratomas. Three tumors, in addition to the benign tissue, had solid, mitotically active areas. Two of these tumors upon transplantation gave rise to progressively growing, potentially lethal tumors which have proven to be permanently transplantable cell lines. Using techniques of light and electron microscopy, immunohistochemistry, flow microfluorometry, and cytogenetics, we have characterized these lines. One is a chondrosarcoma, and one is a glioma:chondrosarcoma mixture. Both are chromosomally different from the parent embryonal carcinoma stem cell line, but both were clearly derived from it.

Animals↗
PubMed1975

Eggshell aspiration in infants.

Two infants inhaled eggshell fragments. The first aspirated a small fragment into the upper part of the trachea and resuscitation attempts resulted in descent of the foreign body to the right lower lobe bronchus. Two attempts at bronchoscopy were unsuccessful and spontaneous disintegration occurred. The second infant aspirated an eggshell fragment to the entrance of the larynx where it was removed by laryngoscopy. Laryngeal or tracheal foreign body in infants under 1 year of age are rare, and the diagnosis and removal are difficult.

Animals↗
PubMed1973

BCG vaccination of children against leprosy: seven-year findings of the controlled WHO trial in Burma.

A controlled study of the efficacy of BCG vaccination for the prevention of leprosy began in Burma at the end of August 1964. This paper presents the findings after 7 years-i.e., the results of 6 annual follow-up examinations up to the end of June 1971. The incidence rate in BCG-vaccinated children 0-4 years of age at intake was lower than that in children in the control group. The protection conferred by BCG was relatively low (44%) and applied only to early cases of leprosy, the great majority tuberculoid cases. BCG vaccination did not protect household contacts or children 5-14 years of age who were not exposed in the household. This reduction must be interpreted in the light of several factors: form of leprosy, bacterial status, lepromin reactivity, evolution of cases, and level of endemicity. Consequently it does not seem probable that the reduction in incidence would substantially affect the pattern or trend of the disease in an area similar to that where the study is being carried out; the probability would be much lower if not nil in regions of relatively low endemicity (1-2 per 1 000 or less).

Adolescent↗
PubMedDate not supplied

Adherence of Helicobacter pylori to gastric carcinoma cells: analysis by flow cytometry.

An in vitro assay using immunofluorescence and flow cytometry for quantitative assessment of the adherence of Helicobacter pylori to cultured human gastric carcinoma (KATO III) cells was developed. Adherence was rapid, saturable, energy dependent, mannose resistant, and significantly inhibited by fetuin, a glycoprotein containing N-acetylneuraminyllactose. Pretreatment of KATO cells with neuraminidase from Clostridium perfringens, however, did not reduce adherence of H. pylori. Ultrastructurally, adherent cells of H. pylori were associated with indentations of KATO cell membranes. KATO cells should prove useful in the investigation of mechanisms of adherence of H. pylori to mammalian cells. Ultimately, this flow cytometric assay may be helpful in assessment of the adherence of laboratory strains of H. pylori directly to surface mucous cells dissociated from biopsied human gastric tissue.

Bacterial Adhesion↗