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G Bosma

Publications and source records attributed to G Bosma.

9 recordsLinked to original sources
PubMed1992

Analysis of the defect in DNA end joining in the murine scid mutation.

Murine severe combined immune deficiency (scid) is marked by a 5,000-fold reduction in coding joint formation in V(D)J recombination of antigen receptors. Others have demonstrated a sensitivity to double-strand breaks generated by ionizing radiation and bleomycin. We were interested in establishing the extent of the defect in intramolecular and intermolecular DNA end joining in lymphoid and nonlymphoid cells from scid mice. We conducted a series of studies probing the ability of these cells to resolve free ends of linear DNA molecules having various biochemical end configurations. We find that the stable integration of linear DNA into scid fibroblasts is reduced 11- to 75-fold compared with that in normal fibroblasts. In contrast, intramolecular and intermolecular end joining occur at normal frequencies in scid lymphocytes and fibroblasts. This normal level of end joining is observed regardless of the type of overhang and regardless of the requirement for nucleolytic activities prior to ligation. The fact that free ends having a wide variety of end configurations are recircularized normally in scid cells rules out certain models for the defect in scid. We discuss the types of DNA end joining reactions that are and are not affected in this double-strand break repair defect in the context of a hairpin model for V(D)J recombination.

Animals↗
PubMed1988

Steroid treatment in acute ischaemic stroke. A comparative retrospective study of 556 cases.

The files of 556 patients with a history of ischaemic stroke were reviewed. The disability and mortality rates were compared between 277 patients with a steroid treatment in the acute stage and 279 without. Comparison of the whole group showed that the steroid-treated patients had less improvement of their disability and a higher mortality rate than the non-steroid group. However, in the former more patients with a severe stroke were present. Statistical analysis of a subset of 208 patients with completed stroke in the middle cerebral artery territory showed no marked difference in the outcome and the adverse reactions between the steroid- and non-steroid-treated patients.

Aged↗
PubMed1987

Isolation and characterization of ubiquinol oxidase complexes from Paracoccus denitrificans cells cultured under various limiting growth conditions in the chemostat.

To obtain more information about the composition of the respiratory chain under different growth conditions and about the regulation of electron-transfer to several oxidases and reductases, ubiquinol oxidase complexes were partially purified from membranes of Paracoccus denitrificans cells grown in carbon-source-limited aerobic, nitrate-limited anaerobic and oxygen-limited chemostat cultures. The isolated enzymes consisted of cytochromes bc1, c552 and aa3. In comparison with the aerobic ubiquinol oxidase complex, the oxygen- and nitrate-limited ones contained, respectively, less and far less of the cytochrome aa3 subunits and the anaerobic complex also contained lower amounts of cytochrome c552. In addition, extra haem-containing polypeptides were present with apparent Mr of 14,000, 30,000 and 45,000, the former one only in the anaerobic and the latter two in both the anaerobic and oxygen-limited preparations. This is the first report describing four different membrane-bound c-type cytochromes. The potentiometric and spectral characteristics of the redox components in membrane particles and isolated ubiquinol oxidase fractions were determined by combined potentiometric analysis and spectrum deconvolution. Membranes of nitrate- and oxygen-limited cells contained extra high-potential cytochrome b in comparison with the membranes of aerobically grown cells. No difference was detected between the three isolated ubiquinol oxidase complexes. Aberrances with already published values of redox potentials are discussed.

Aerobiosis↗
PubMed1987

Subfractionation and characterization of soluble c-type cytochromes from Paracoccus denitrificans cultured under various limiting conditions in the chemostat.

Soluble c-type cytochromes were partially purified from Paracoccus denitrificans cells grown in succinate- and methanol-limited aerobic, nitrate-limited anaerobic and oxygen-limited chemostat cultures. Five c types could be distinguished with the following apparent molecular masses, absorption maxima and midpoint potentials. (a) 9.2 kDa, 549 nm and +190 mV; (b) 14 kDa, 549 nm and +227 mV; (c) 22 kDa, 552 nm and +190 mV; (d) 30 kDa, 552.7 nm and +160 mV; (e) 45 kDa, a dihaem: 555 nm, +128 mV and 551 nm, -163 mV. The 14-kDa polypeptide was present under all growth conditions examined and most probably is the already well characterized cytochrome c550. In methanol-limited grown cells three additional cytochromes were found, the 9.2-kDa, 22-kDa and 30-kDa ones. Under oxygen-limited conditions the 45-kDa and under anaerobic growth conditions small quantities of the 30-kDa and 45-kDa cytochromes c were present. Based on the apparent molecular masses the 14-kDa, 22-kDa, 30-kDa and 45-kDa cytochromes may also be present in membrane-fractions.

Aerobiosis↗
PubMed1987

The respiratory chain and energy conservation in the mitochondrion-like bacterium Paracoccus denitrificans.

Paracoccus denitrificans has a flexible electron transport chain containing various inducible dehydrogenases, oxidases and reductases. The sequence of electron carriers and stoichiometry of energy transduction is well known, with the exception of all functional aspects of the different c-type cytochromes. The mitochondrion-like characteristics of the respiratory chain have stimulated much research at the molecular level, which should help to elucidate the structure-function relationship of the components of the different respiratory complexes isolated.

Adenosine Triphosphate↗
PubMed1976

Analysis of antibody populations to oligo-D-alanine. VIII. Sequential studies on properties of antibody subpopulations: rate constant, affinity, and isoelectric focusing spectrum.

Allotypically marked antisera to the hapten oligo-D-alanine were studied over periods up to 10 months in individual mice and in serial transfers of both nonimmune and memory cells to irradiated recipients. Parameters observed were divalent association rate constants, affinity and autoradiography of isoelectric focusing (IEF) spectra. The two allotypic subpopulations of heterozygous mice are shown to be independent with respect to affinity. Association rate constant, affinity, and IEF spectra of the antibody populations remain largely stable in most mice over prolonged periods. There is an occasional isolated dramatic change in a single property of one allotypic subpopulation; this may be in the direction of either lower or higher rate constant or affinity. While different recipients of naive spleen cells from a single donor, when immunized, differ one from the other in the measured antibody properties, the characteristics now established in each recipient persist in a lineage of transferred memory cells up to 4 generations, with infrequent changes in isolated properties of only one allotypic subpopulation. The limited changes observed would be in agreement with a model of moderate somatic variability superimposed on a small spectrum of germ line genes.

Alanine↗
PubMedDate not supplied

The cortisol responses to 5-hydroxytryptophan, orally, in depressive inpatients.

Baseline cortisol levels at 8:00 a.m. and the cortisol responses at 90 and 120 min after oral administration of 200 mg 5-hydroxytryptophan (5-HTP) (L-isomer, non-enteric-coated) were assessed in 65 depressed inpatients. Patients were categorized according to DSM-III as major (296.22; 296.32; 296.23; 296.33; 296.24; 296.34) and minor (300.40; 309.00; 296.82) depressives. We observed a significant rise of plasma cortisol in patients with major depression at 90 (P = 0.0001) and 120 (P = 0.002) min, but not in patients with minor depression. Patients with major depression showed significantly higher cortisol responses than those with minor depression (P = 0.016). This significant rise of plasma cortisol after 5-HTP could be attributed to sex-linked differences: we observed significant (P = 0.0065) rises in cortisol responses in women with major depression compared to depressed men and women with minor depression. These differences could not be attributed to age, concomitant benzodiazepine use or pre/postmenopausal status. Baseline cortisol correlated negatively with the cortisol response to 5-HTP. The increased cortisol responses in women with major depression remained significant even after the effects of baseline cortisol were partialled out. This rise in cortisol response can be explained by an increased responsiveness of the hypothalamic-pituitary-adrenal axis to 5-HTP.

5-Hydroxytryptophan↗