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Biomedical subjects

J Powell

Publications and source records attributed to J Powell.

At least 253 records · Page 14Linked to original sources
PubMed1984

Evidence for a stem cell common to hematopoiesis and its in vitro microenvironment: studies of patients with clonal hematopoietic neoplasia.

The origin and nature of cells forming the in vitro microenvironment in long-term cultures of human marrow were studied in five patients with clonal myeloproliferative disorders who were heterozygous for glucose-6-phosphatase dehydrogenase (G6PD). The results showed that cells in the adherent stromal layer forming the in vitro microenvironment were derived from the same clonal progenitors involved by the neoplasm in the four patients whose diseases originated in multipotent stem cells. In contrast, stromal cells were derived from normal progenitors in a patient with acute non-lymphocytic leukemia whose clone showed differentiative expression confined to cells in the granulocytic lineage. Mixing experiments demonstrated that the G6PD type displayed by the adherent marrow stromal cells was not obscured by contaminating non-adherent hematopoietic cells or marrow fibroblasts. The data suggest the existence of a pluripotent cell in normal hematopoiesis that gives rise to hematopoietic cells and to their micro-environment.

Adult↗
PubMed1984

The relationship of contrast sensitivity functions to sports vision.

Contrast sensitivity, a more recent test of visual function, has never been studied in its relationship to sports vision. The hypothesis that contrast sensitivity functions among college varsity level baseball players significantly differs from that of a random sample of optometry students was tested using Arden grating plates. A statistically significant difference was found at the 98 percent confidence level, demonstrating that in this study, a sample of college varsity level baseball players have higher level contrast sensitivity functions than those of a randomly selected sample of Southern California College of Optometry students.

Adolescent↗
PubMed1984

The generation of human long-term marrow cultures from marrow depleted of Ia (HLA-DR) positive cells.

Successful long-term cultures were generated from marrow buffy-coat cells incubated with either of two monoclonal anti-Ia antibodies, 7.2 and HBIOa, and complement. The mean CFU-GM toxicity for 7.2 and HBIOa was 81% and 94%, respectively, of the complement control. Cultures generated from marrows treated with 7.2 and complement produced between 30% and 163% of the CFU-GM (mean, 78.2 +/- 52.4%) and 33% of the BFU-E produced by the complement control cultures. Long-term cultures from marrows treated with the more cytotoxic HBIOa antibody yielded 261% of the CFU-GM present at culture initiation. Our data suggest that the progenitor cells necessary for generation of long-term cultures from human marrow are Ia-negative and may represent less mature stem cells than those measurable by semisolid colony assays. Furthermore, marrow treated with cytotoxic anti-Ia antibodies may be suitable for use in autologous transplantation.

Antibodies, Monoclonal↗
PubMed1983

Influence of intraperitoneal dialyzate on blood pressure during continuous ambulatory peritoneal dialysis.

Blood pressure (BP) of patients on continuous ambulatory peritoneal dialysis (CAPD) must be well controlled. The present study tests a clinical impression that BP recordings are higher with dialyzate within the peritoneal cavity than after it is drained out. 8 CAPD patients had systolic BP, diastolic BP and heart rate measured both with dialyzate in situ and after drainage. Paired t-tests showed systolic BP and diastolic BP but not heart rate to be significantly (P less than 0.05) higher with dialyzate in situ. To avoid a false impression of good BP control it is recommended patients on CAPD measure BP with dialyzate in situ.

Adult↗
PubMed1981

Cellular fatty acid composition of organisms frequently associated with human infections resulting from dog bites: Pasteurella multocida and groups of EF-4, IIj, M-5, and DF-2.

The cellular fatty acid composition of Pasteurella multocida and four unclassified groups of gram-negative bacteria (EF-4, M-5, IIj, and DF-2) which are frequently associated with human dog-bite infections was determined by gas-liquid chromatography. Strains of P. multocida were readily distinguished from the unclassified groups by the presence of 3-hydroxy myristic acid (3-OH- 14:0). Groups M-5 and EF-4 were characterized by the presence of 3-hydroxy lauric (3-OH-12:0) acid. Only group EF-4 organisms contained 2-OH-16:0, a-17:0, and 17:0 cyclopropane acids. Groups IIj and DF-2 differed from the other groups by the presence of large amounts of a branched-chain 15-carbon acid (i-15:0); they differed from each other by the presence of i-2-OH-15:0 and i-17:1 acids in IIj, which were absent in DF-2. The data indicate that gas-liquid chromatographic analysis for cellular fatty acids provides an additional test for rapid differentiation of these gram-negative organisms associated with dog-bite infections. Similarities observed in the fatty acid compositions of Flavobacterium, IIj, and DF-2 suggest that these two unclassified groups may be additional species of Flavobacterium.

Animals↗
PubMed1980

The effect of ampicillin on oral contraceptive effectiveness.

The effectiveness of oral contraceptives with concomitant use of ampicillin has been questioned. Eleven volunteer subjects were studied during 2 consecutive menstrual cycles; they were given Demulen with placebo or ampicillin during each of the cycles. Serum estradiol (E2), progesterone (P4), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were evaluated on days 13 and 19 of each cycle. Testosterone-binding globulin (TeBG) capacity and ferning of cervical mucus were evaluated on day 13 of each cycle. Subjective symptoms were recorded. All cycles appeared to be anovulatory. Steroid suppression was present in 10 of 11 patients during both cycles. Estrogen-dependent TeBG was not affected by ampicillin. It is possible that cervical mucus ferning was improved by concurrent ampicillin administration. Ampicillin appears unlikely to diminish the effectiveness of the oral contraceptive studied.

Adult↗
PubMed1980

Necrotizing enterocolitis. Epidemic following an outbreak of Enterobacter cloacae type 3305573 in a neonatal intensive care unit.

Twelve cases of necrotizing enterocolitis (NEC) occurred within three weeks in a neonatal intensive care unit (NICU) with 325 annual admissions. Enterobacter cloacae type 3305573 was found in stool and/or blood cultures from affected babies prior to the onset of the disease. This bacterium could not be grown in cultures from infants in the same NICU six weeks later. A causal relationship between E cloacae and the epidemic of NEC is suggested.

Cross Infection↗