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Biomedical subjects

G Peter

Publications and source records attributed to G Peter.

At least 145 records · Page 8Linked to original sources
PubMed1975

[The evaluation of the cyclophosphamide sensitivity of human tumours by determining the incorporation of tritiated uridine and thymidine into the nucleic acids of human tumor cells in vitro in presence of 4-hydroxycyclophosphamide (author's transl)].

A new in vitro assay for screening the sensitivity of human tumour cells against Cyclophosphamide has been developed. While biologically activated Cyclophosphamide was unsuitable because of unpurities in the material, synthetic 4-Hydroxycyclophosphamide was shown to inhibit the incorporation of tritiated uridine and thymidine into the nucleic acids of human tumour cells in vitro. 29 tumours including 14 mammarial carcinomas, 8 ovarial carcinomas and 7 other malignant tumours were tested. While 12 tumours showed a significant and 5 only a slight inhibition of the 3H-uridine incorporation in vitro. 12 tumours showed no effect. Histologically none-differentiated tumours were more sensitive against 4-Hydroxycyclophosphamide as compared with the more differentiated ones. First observations point to 4-Hydroperoxycyclophosphamide instead of 4-Hydroxycyclophosphamide as a more suitable form of activated Cyclophosphamid for the in vitro assay of Cyclophosphamide sensitiveness because of the higher stability and better availability of this compound.

Antineoplastic Agents↗
PubMed1975

Studies on the fate of homologous DNA applied to seedlings of Matthiola incana.

Seedlings of Matthiola incana (crucifer) are able to take up exogenous homologous DNA by the roots. DNA homogenously labelled with [3H]adenine and 5-bromodeoxyuridine is incorporated into the plants in a macromolecular form. Intact donor DNA and a fraction with a buoyant density intermediate between that of the donor and the recipient DNA can be recovered. Analysis of this intermediate fraction by ultrasonication and alkali treatment allows the suggestion that homologous DNA is integrated as a double-stranded DNA which becomes covalently linked to the recipient DNA. Control experiments in which seedlings were incubated in a mixture simulating donor DNA degradation products in the presence and absence of unlabelled competitors suggest that these results are not due to the breakdown of donor DNA and reincorporation of the products during DNA synthesis in the recipient plants. When ultrasonicated or thermally denatured DNA is applied to the plants it may be degraded and reused for recipient DNA synthesis but it is not recovered in a macromolecular form. The possibility that the intermediate DNA fraction arises by bacterial contamination of the plants can be excluded by several arguments. Autoradiographic studies show that at least part of the radioactivity of the donor DNA taken up by the plants is associated with the cell nucleus.

Adenine↗
PubMed1975

Studies on the species, amount and base composition of nucleic acids in psoriatic scales and normal horny layer.

The amount of RNA as well as DNA is considerably increased in psoriatic scales as compared with normal horny layer; RNA was characterized as a low-molecular tRNA; as concerns the base composition of DNA, no particularities in comparison with other DNA species were found, and the base composition of tRNA revealed that cytosine and guanosine are in excess; pseudouridine could not be detected in psoriatic tRNA.

Adolescent↗
PubMed1975

Circulating polyribophosphate in Hemophilus influenzae, type b meningitis. Correlation with clinical course and antibody response.

In systemic infections caused by Hemophilus influenzae, type b, the capsular polysaccharide, polyribophosphate, is released into the circulation. Polyribophosphate was quantitated in serial serum and cerebrospinal fluid samples from 45 children with H. influenzae, type b meningitis by means of a radiolabeled antigen-binding inhibition assay. Polyribophosphate was regularly found in acute serum and cerebrospinal fluid samples and could be detected in unbound form for periods of 1-30 days after initiation of effective therapy. Complexes of polyribophosphate dissociable with acid and pepsin were detected in serum samples from 17 patients, in one case for a period of 145 days after hospitalization. Polyribophosphate levels and patterns of clearance were studied in relation to hospital course and antibody response. Patients with prolonged antigenemia had protracted fevers and severe neurological symptoms during hospitalization, frequently with focal complications.Antipolyribophosphate antibody responses were detected during the first 100 days of convalescence by radioimmunoassay in 79% of the patients studied, including 60% of the children 1 yr or less in age. The intensity of antibody response although clearly related to the age of the patient, was more reliably predicted by the efficiency of antigen clearance. Antibody responses were uniformly of low magnitude in patients with prolonged antigenemia, irrespective of age. Paients who failed to develop antibody to polyribophosphate after meningitis also exhibited impaired antigen clearance. These studies suggest that mechanisms necessary for clearance of polyribophosphate may influence the development and intensity of the humoral immune response and raise the possibility of developmental deficiencies in the clearance system in infants and children.

Age Factors↗
PubMed1975

Hemophilus influenzae meningitis at the Children's Hospital Medical Center in Boston, 1958 to 1973.

Three hundred ninety-seven children were admitted to the Children's Hospital Medical Center, Boston between 1958 and 1973 with H. influenzae meningitis. The annual rate of admission and the percent of all cases of bacterial meningitis were not changed from that of the preceding decade. The age incidence was strikingly similar to that reported from this hospital for 1920 to 1932.

Age Factors↗
PubMed1972

Immunization of humans with polyribophosphate, the capsular antigen of Hemophilus influenzae, type b.

In human volunteers, single injections of purified polyribophosphate elicited antibodies detectable by passive hemagglutination and by serum bactericidal and opsonizing activities against viable Hemophilus influenzae, type b. All three activities rose by 2 wk to maximal levels, at which they remained for at least 6 months. Doses of 1 mug elicited antibody responses in nearly all recipients; higher doses of the antigen, however, produced larger increases in titer. Booster doses of 1 mug given at 6 months did not further increase the antibody titers. A tuberculin-like response was often observed at the site of injections given intradermally.

Animals↗