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Biomedical subjects

L Graf

Publications and source records attributed to L Graf.

At least 55 records · Page 3Linked to original sources
PubMed1982

Nucleotide sequence of a Euglena gracilis chloroplast gene coding for the 16S rRNA: homologies to E. coli and Zea mays chloroplast 16S rRNA.

The nucleotide sequence of 16S rDNA from Euglena gracilis chloroplasts has been determined representing the first complete sequence of an algal chloroplast rRNA gene. The structural part of the 16S rRNA gene has 1491 nucleotides according to a comparative analysis of our sequencing results with the published 5'- and 3'-terminal "T1-oligonucleotides" from 16S rRNA from E. gracilis. Alignment with 16S rDNA from Zea mays chloroplasts and E. coli reveals 80 to 72% sequence homology, respectively. Two deletions of 9 and 23 nucleotides are found which are identical in size and position with deletions observed in 16S rDNA of maize and tobacco chloroplasts and which seem to be characteristic for all chloroplast rRNA species. We also find insertions and deletions in E. gracilis not seen in 16S rDNA of higher plant chloroplasts. The 16S rRNA sequence of E. gracilis chloroplasts can be folded by base pairing according to the general 16S rRNA secondary structure model.

Base Sequence↗
PubMed1982

The primary structure of human beta-lipotropin. Further peptide sequencing resolves the controversy and suggests the existence of only one human beta-lipotropin.

Human beta-lipotropin isolated in Hungary from frozen pituitary glands was purified by high-performance liquid chromatography in Canada. The amino acid sequence of the first 30 residues was determined. Trypsin, trypsin/papain, and trypsin/thermolysin fragments were obtained for the disputed region containing residues 9-25 of beta-lipotropin. Their amino acid composition and sequence established beyond doubt that only one human beta-lipotropin sequence is present. These results suggest the presence of only one gene coding for human pro-opiomelanocortin, the precursor of adrenocorticotropin and beta-endorphin and resolve the controversy over the sequence of human beta-lipotropin.

Amino Acid Sequence↗
PubMed1982

Isolation and characterization of mouse beta 2-microglobulin allotypes.

Two allelic forms of mouse beta 2-microglobulin (beta 2m), the smaller polypeptide chain of the H-2 histocompatibility antigens, were purified from urine and partially characterized. The isoelectric points of the two allotypes are 7.4 (beta 2ma) and 8.1 (beta 2mb). The electrophoretic mobility of beta 2ma is decreased by reduction, whereas the mobility of beta 2mb is not. Urinary beta 2m can replace endogenous beta 2m in mouse H-2 histocompatibility antigens.

Alleles↗
PubMed1981

Two allelic forms of mouse beta 2-microglobulin.

Two allelic forms of mouse beta 2-microglobulin (beta 2m), the small polypeptide chain of H-2 histocompatibility antigens, have been identified. The two forms can be distinguished by NaDodSO4/polyacrylamide gel electrophoresis. All inbred mouse strains express a single beta 2m isotype. Mice heterozygous for beta 2m synthesize both forms, showing codominant expression of beta 2m alleles. In mice heterozygous for both H-2 and beta 3m, individual H-2 histocompatibility antigens associate with both beta 2m forms. Preliminary structural studies indicate differences in peptide composition between the two forms.

Alleles↗
PubMed1981

An immunological model of epilepsy: seizures induced by antibodies to GM1 ganglioside.

Following observations that the intracerebral injection into rats of antiserum to brain gangliosides resulted in recurrent epileptiform activity and that seizure activity was not seen if antibodies were removed by absorption of the antiserum with pure GM1 ganglioside, a study was undertaken to establish characteristics of the immunological agents used to produce this model of epilepsy. It was determined that the potencies (antibody titers with GM1 ganglioside) of antiganglioside sera can be correlated with the intensities of epileptiform activity they induce; that immunoglobulin fractions from antiganglioside sera are even more effective biologically than the antisera; and that antibodies to GM1 ganglioside purified by affinity chromatography can also induce recurrent epileptiform discharges but are not as effective as either native antiserum or immunoglobulin fractions.

Animals↗
PubMed1980

Synaptic membrane antigens: detection and characterization.

Analysis of the antigenic components of synaptic membranes presents several problems caused by detergents required to solubilize the proteins. These problems involve detection of the reaction between antibodies and proteins in the detergent extract as well as characterization of the individual antigens after further purification. We found a satisfactory solution for analysis of rat synaptic membranes by using rocket immunoelectrophoresis with an intermediate gel containing 0.5% berol to sequester sodium dodecyl sulfate (SDS) and an antibody gel containing 0.1% berol to maintain the solubility of the proteins. With antiserum prepared against a highly purified synaptic membrane fraction, these conditions gave rocket heights proportional to protein concentration (for the major rocket) and showed no reactions with membrane extracts of liver, kidney and spleen. By separation on gradient slab gels containing SDS, 4 antigenic polypeptides were found in Berol extracts of synaptic membrane, having apparent molecular sizes of 56,000, 58,000, 62,000 and 66,000 daltons. The SDS extract of the berol insoluble residue contained 3 antigenic polypeptides (12,500; 15,000, 16,500 daltons). The combined use of gradient slab gel electrophoresis in SDS and rocket immunoelectrophoresis with an intermediate gel to remove SDS provides a sensitive and rapid method for definitive identification of individual antigenic components in detergent extracts of membrane and for further purification of these antigens.

Animals↗
PubMed1980

Glial fibrillary acidic protein and Alzheimer-type senile dementia.

Glial fibrillary acidic protein (GFAP), a protein that is associated with 9-nm filaments of astrocytes, was observed to be increased in the astrocytes surrounding senile plaques in patients with Alzheimer dementia and in aged subjects without dementia. A few GFAP-positive fibers were seen in the centers of plaques. These results emphasized the selectivity of senile changes; whereas some cells seemed to undergo degeneration or dysfunction, other cells--astrocytes--maintain their capacity for reaction and may increase the formation of at least one protein, GFAP.

Alzheimer Disease↗
PubMed1979

Glial fibrillary acidic protein in ependymomas and other brain tumors. Distribution, diagnostic criteria, and relation to formation of processes.

Glial fibrillary acidic protein (GFAP) was studied in ependymomas by the three-step immunoperoxidase method and compared to results in astrocytomas and normal tissues. An order of reactivity for GFAP is presented. Diagnostic criteria, based on GFAP content, are proposed. In ependymomas GFAP-positive cells give rise to only some of the tumor cells, usually those forming tubules and perivascular arrangements. It is hypothesized that the same GFAP-positive cells may form tubules at their luminal poles and may produce perivascular arrangements at their other poles. The aberrant regulation associated with neoplastic transformation in glia is often, but not always, reflected in increased GFAP content. In both astrocytes and ependymal cells GFAP may have a similar function since in both cells the increase in GFAP appears to be related to the development of fibrillary processes.

Astrocytes↗
PubMed1977

Identification of glial fibrillary acidic protein by the immunoperoxidase method in human brain tumors.

The immunocytochemical localization of glial fibrillary acidic portein within glioma cell bodies and their processes by the immunoperoxidase method is demonstrated to be of diagnostic value. This method has advantages over "special" stains because it is not so dependent upon color alone, and because it identifies a specific protein in the cells. The immunoperoxidase method using antiserum to glial fibrillary acidic protein is shown to be useful for the differentiation of mixed glial and mesenchymal tumors, and for the diagnosis of tumors in which a glial or mesenchymal cell origin is in doubt.

Brain Neoplasms↗
PubMed1976

Antiserum to brain gangliosides produces recurrent epileptiform activity.

A single injection of 10 microliters of antiserum to total brain ganglioside onto (and into) the sensorimotor cortex of the rat resulted in recurrent spiking in the cortical electroencephalogram, lasting from 7 to 17 days. Absorption of antibody with pure monosialoganglioside (GM1) completely abosished the effect. Spiking was reactivated after 4 weeks by intramuscular injection of pentylenetetrazole.

Action Potentials↗