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Biomedical subjects

R Conrad

Publications and source records attributed to R Conrad.

At least 109 records · Page 6Linked to original sources
PubMed1978

Metabolism of fructose in Thiocapsa roseopersicina.

Thiocapsa roseopersicina strain 6311 grew phototrophically in a mineral medium containing fructose as sole electron donor and carbon source with a doubling time of 11--13 h, provided the mineral medium contained vitamine B12 (50 ng/ml), not more than 20 mM phosphate, and the culture was preincubated in the dark for 24 h. In fructose-grown cells but not in autotrophically grown cells, the cell-protein content was strongly reduced when vitamine B12 was growth limiting, while the carbohydrate content was increased. Growth on fructose as sole carbon source was inhibited by the addition of sulfide or thiosulfate; growth inhibition was relieved in the presence of bicarbonate. No growth on fructose was observed anaerobically in the dark; aerobic growth in the dark was poor. Analysis of enzyme activities in fructose- and acetate-grown cells indicated that fructose was catabolized via fructose-1-phosphate and the EMBDEN-MEYERHOF pathway. The operation of the EMBDEN-MEYERHOF pathway was confirmed by incorporation of 1-14C-, 3-14C-, and 6-14C-fructose into the spirilloxanthin fraction and analysis of its specific radioactivity.

Aerobiosis↗
PubMed1978

An alternative pathway for the degradation of endogenous fructose during the catabolism of sucrose in Rhodopseudomonas capsulata.

Sucrose catabolism was studied in Rhodopseudomonas capsulata. Sucrose was hydrolysed by the action of a constitutive cytoplasmic sucrase. The use of a glucose-6-phosphate dehydrogenase-deficient mutant and radiorespirometric experiments demonstrated that both the glucose and fructose moieties of sucrose were catabolized via the Entner-Doudoroff pathway. This result was confirmed by enzyme analysis and studies on sugar assimilation. All the enzymes of the Entner-Doudoroff pathway were present in bacteria grown on secrose but fructokinase (EC 1.7.1.4) activity was relatively low. In contrast, phosphoenolpyruvate:fructose phosphotransferase and 1-phosphofructokinase, the key enzymes for the catabolism of exogenous fructose, were only partially induced. Bacteria grown on sucrose and treated with chloramphenicol were, therefore, not able to assimilate exogenous fructose. We conclude that under these conditions endogenous fructose is catabolized via the Entner-Douboroff pathway, while exogenous fructose is degraded via fructose 1-phosphate and the Embden-Meyerhof pathway.

Fructose↗
PubMed1978

Regulation of glucose, fructose and sucrose catabolism in Rhodopseudomonas capsulata.

Regulation of glucose, fructose and sucrose catabolism was studied in Rhodopseudomonas capsulata grown under phototrophic conditions. The sequence of preference for the utilization of the sugar substrates was fructose, glucose, sucrose. The presence of a preferred substrate did not completely suppress the utilization of the less preferred. Glucose-6-phosphate dehydrogenase, the key enzyme of glucose and sucrose catabolism, exhibited sigmoidal substrate saturation curves and was inhibited by phosphoenolpyruvate, whereas 1-phosphofructokinase, the key enzyme of fructose catabolism, exhibited hyperbolic substrate saturation curves and was not inhibited by phosphoenolpyruvate. Since phosphoenolpyruvate is a common intermediate of glucose, fructose and sucrose catabolism, the control of glucose-6-phosphate dehydrogenase may be responsible for the preferential utilization of fructose.

Fructose↗
PubMed1977

Conversion of oxy- into methemerythrin in the presence of anions.

The interaction of oxyhemerythrin (HrO2) with cyanate and azide ions (X-) is biphasic. The rapid loss of HrO2 is monitored at 500 nm using stopped flow. The dependence of the pseudo-first order rate constant on [HrO2], [X-], and [O2] can be interpreted by the scheme HrO2 in equilibrium Hr + O2 K1 Hr + X-in equilibrium HrX- k2, k-2, k2 At 25 degrees, pH = 6.3 and I = 0.15 M; for X- = CNO-, k2 = 59 M-1 S-1 and k-2 = 0.019 S-1; and for X- = N3-, k2 = 1.6 X 10(2) M-1 S-1 and k-2 = 0.10 S-1. The values of K1K2 from kinetics are in good agreement with those obtained from spectral and [O2] determinations of equilibrated mixtures of Hr, CNO-, and O2. The second step has been analyzed separately by flow observations of the small spectral changes accompanying addition of X- to deoxyhemerythrin. The slower, stoichiometric formation of methemerythrin cyanate or azide has also been studied and second order rate constants for reaction of HrO2 with X- determined (N3-, 0.34 M-1 S-1 and CNO-, 0.08 M-1 S-1 at 25 degrees and pH = 6.3). These are compared with those for accelerated formation of the methemerythrin ligand adduct in the same conditions in presence of NO2- (0.31 M-1 S-1), HCO2- (8.3 X 10(-3) M-1 S-1), F- (0.12 M-1 S-1), Cl- (1.4 X 10(-4) M-1 S-1), and imidazole (4 X 10(-3) M-1 S-1 at pH 8.0). No rapid pre-equilibria are observed in the case of the latter ligands. The effect of pH is examined.

Animals↗
PubMed1977

Different degradation pathways for glucose and fructose in Rhodopseudomonas capsulata.

In Rhodopseudomonas capsulata the enzymes of the Entner-Doudoroff pathway and the Embden-Meyerhof pathway have been examined. Fructose-grown cells contained inducible activities of phosphoenolpyruvate-fructosephospho-transferase and 1-phosphofructokinase and only low levels of fructokinase and 6-phosphofructokinase. Although fructose-grown cells contained, in addition, all the enzymes of the Entner-Doudoroff pathway together with fructose-1,6-diphosphatase and phosphoglucose isomerase, the Entner-Doudoroff pathway was not operative in fructose catabolism and served only the degradation of glucose. The functional separation of glucose and fructose catabolism via the Entner-Doudoroff and a modified Embden-Meyerhof pathway, respectively, was confirmed by different approaches: 1. Radiorespirometric experiments with glucose and fructose labelled in positions 1, 2, 3, 3+4 and 6 have been carried out. The pattern of 14CO2-evolution from position-labelled glucose was characteristic for the Entner-Doudoroff pathway, that from position-labelled fructose for the Embden-Meyerhof pathway. 2. In the presence of arsenite up to 50% of glucose- and fructose-carbon was excreted as pyruvate. Using 1-14C-glucose, 86% of the pyruvate was labelled in the carboxyl group, whereas using 1-14C-fructose only 19% of the pyruvate was labelled in the carboxyl group. 3. A glucose-6-phosphate dehydrogenase-deficient mutant was isolated which lacked a functional Entner-Doudoroff pathway but which was unaltered in its ability to grow on fructose.

Fructose↗
PubMed1976

Diagnostic and therapeutic efficacy of cervical conization.

Cervical conization was perfromed on 756 patients at the University of Kentucky Medical Center from July 1, 1964, to January 1, 1973. Sixty-six patients were pregnant at the time of conization. Eighty-six per cent of patients with cytologic findings of carcinoma in situ had histologic verification of carcinoma in situ or severe dysplasia, and there was absolute correlation between cytology and histology in 75 per cent of patients will occult invasive cancer. Cervical biopsies without colposcopic direction predicted either severe dysplasia or carcinoma in situ in 77 per cent of cases but were accurate in only seven of 24 patients with occult invasive cancer. Carcinoma in situ was present in 30 per cent of hysterectomy specimens following conization but recurred in only seven per cent of patients followed without hysterectomy. Recurrent carcinoma in situ following hysterectomy was more common in patients with residual intraepithelial cancer in the uterus but was independent of the size of the vaginal cuff removed. Major postconization complications requiring hospitalization occurred in 3.4 per cent of nonpregnant patients and in 7.5 per cent of pregnant patients.

Adult↗
PubMed1975

The Papago psychology service: a community mental health program on an American Indian reservation.

A community psychology service run by the Papago Indian tribe and staffed largely by Papago Indians who have been trained as mental health workers is described. This service is unique among mental health services for Indians in that the tribe has complete control of the funds for the service and sets its own policies. It was developed for a rather traditional Indian group, and the culture, the traditions, and the wishes of the Papago community were respected. Consultation with medicine men was built into the program from the start, and adaptation of mental health techniques to fit the culture is stressed. Before this clinic was established, few mental health resources were directly available to the reservation. Similar to other Indian tribes, the Papagos are economically disadvantaged, with an unemployment rate of over 50%, low educational attainment, and very high rates of alcoholism, suicide, and vehicular accidents. The topics covered are the tribe's view of health programs for its people, the present Papago community and traditional means of treatment, traditional psychotherapy adapted to Papago culture, the indigenous Papago mental health worker, and the non-Indian professional consultant.

Administrative Personnel↗