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Biomedical subjects

M L Wolf

Publications and source records attributed to M L Wolf.

9 recordsLinked to original sources
PubMed1992

Expression of a chimeric helix-loop-helix gene, Id-SCL, in K562 human leukemic cells is associated with nuclear segmentation.

We have designed a chimeric gene, Id-SCL, in which the 3' helix-loop-helix encoding portion of the presumptive oncogene SCL/tal is joined to the 5' coding portion of Id, an inhibitory helix-loop-helix gene. The predicted protein product of this chimeric gene contains the helix-loop-helix dimerization domain of SCL/tal, but, lacking a basic DNA binding domain, is predicted to have the inhibitory function of the Id product. Expression of the Id-SCL fusion gene in stably transfected K562 cells reproducibly resulted in nuclear segmentation and depressed growth rates; both of these phenotypic effects demonstrated a dosage dependence on the levels of Id-SCL mRNA and protein expressed in the various clones. Electron microscopy of cells expressing high levels of Id-SCL mRNA showed a significant increase in cytoplasmic perinuclear thin filaments and diminution of marginal heterochromatin in the nuclei. No other changes in hematopoietic differentiation status were observed in association with Id-SCL expression. Expression of intact Id and SCL/tal genes, as well as deletion mutants of Id and SCL/tal, independently transfected into K562 cells, indicated that the nuclear segmentation effect is dependent on the presence of a protein possessing a helix-loop-helix domain but lacking a basic domain. Our studies suggest that the balance of transcriptional inhibitory and stimulatory helix-loop-helix proteins in cells may be important determinants of proliferation and of structural organization within cells.

Amino Acid Sequence↗
PubMed1991

Development of a bone marrow culture for maintenance and growth of normal human B cell precursors.

The absence of long term bone marrow cultures for studying the growth and differentiation of human B cell precursors (BCP) has placed restrictions on the ability to analyze the early stages of human B cell ontogeny. We now describe a bone marrow-derived adherent cell microenvironment that maintains human BCP for several weeks in vitro. The adherent cells are maintained in a serum-free tissue culture medium, and consist of a predominant population of CD10+ fibroblast-like cells and a minor population of CD10+/nonspecific esterase+ macrophages. Adherent cell cultures seeded with fresh or cryopreserved fetal bone marrow, or purified CD10+/surface IgM- cells, provide a supportive microenvironment for lymphoid cells with a predominant phenotype of CD10+/CD19+/HLA-DR+/surface IgM-. Supplementation of the adherent cell cultures with human IL-7 induces active growth of BCP during the first 14 to 21 days of culture. However, the expansion of these cells does not continue past 21 days, and the cultures undergo a steady decline in BCP. Analysis of adherent cell conditioned medium revealed the presence of an unidentified soluble factor (or factors) that acts in concert with IL-7 to promote the growth of CD10+/surface IgM- cells. This culture system will be useful in elucidating the patterns of gene expression and growth factor requirements that characterize normal human B cell ontogeny, and perturbations of normal B cell ontogeny that lead to immunodeficiency and leukemia.

Antigens, CD↗
PubMed1991

The use of LIS for blood usage review. Experience in a children's hospital.

To comply with the requirements of the Joint Commission for the Accreditation of Healthcare Organizations (JCAHO) and to facilitate the review process, the authors designed a program to screen for the appropriateness of packed red cell (PRC) and platelet concentrate (PLT) transfusions. The purpose of this report is to describe the methodology of the review process. A quality assurance (QA) monitor was created in the Laboratory Information System (LIS) to screen indicators: hemoglobin for PRCs and platelet count for PLTs. Numerical value limits were defined to determine acceptable ranges. Each week, the LIS compiles a list of all patients who received transfusions and for whom the QA monitor determined that the values of the screened indicators were outside the defined appropriate limits. A detailed transfusion record is generated for each patient identified. During a six-month evaluation of this program, a total of 1,788 PRC and 3,109 PLT units were transfused. Of these, 582 PRC (32.5%) and 2,219 PLT (71.4%) units were within the acceptable guidelines. Lists for the remaining 1,206 PRCs and 890 PLTs were generated. Review of the transfusion record and other laboratory values from the LIS established the appropriateness of 1,052 PRC and 782 PLT transfusions. At the conclusion of the six-month period, the medical charts for 181 (11%) PRC and 108 (4.5%) PLT transfusions required chart review. This method provided major reduction in time of the transfusion review process. Similar guidelines may be used to monitor other transfusion products such as fresh frozen plasma.

Blood Transfusion↗
PubMed1990

The response of splenic lymphocytes removed from hypophysectomized-orchidectomized hamsters to phytohemagglutinin correlates with somatic growth but not with circulating prolactin levels.

To examine the relationship between PRL and the mitogenic capacity of lymphocytes, we studied the relationships among circulating PRL levels, somatic growth, and the response of splenic lymphocytes to the mitogen phytohemagglutinin (PHA) in hamsters. In the first experiment, no differences were observed in the PHA responses of lymphocytes removed from intact or hypophysectomized-orchidectomized hamsters. No relationships were observed between circulating PRL levels and either the PHA responses or somatic growth. However, significant positive correlations were observed between the somatic growth of intact or hypophysectomized-orchidectomized hamsters and the PHA responses (r = 0.741; P less than 0.01 for intact hamsters; r = 0.642; P less than 0.01 for hypophysectomized-orchidectomized hamsters). In three subsequent experiments we tested the effects of placing muscle or hypophysial allografts in hypophysectomized-orchidectomized hamsters on somatic growth, the PHA responses, and circulating PRL levels. Neither type of allograft altered the somatic growth of hypophysectomized-orchidectomized hamsters. The hypophysial allografts did elevate serum PRL levels. In all experiments the responses of splenic lymphocytes to PHA showed a significant positive correlation with somatic growth, but not with serum PRL levels. These results minimize a role of PRL in this particular lymphocyte response. The results suggest that a strong correlation exists between mechanisms responsible for somatic growth in hypophysectomized-orchidectomized hamsters and the immune status, as determined by the response to PHA, of the animals. This relationship also may exist in intact hamsters.

Adrenal Glands↗
PubMed1988

Altering body position affects intraocular pressure and visual function.

Intraocular pressure (IOP) can be altered by changing body position. This report describes two experiments evaluating variations in IOP, as well as neural functioning of the retina and visual cortex (as measured by pattern-reversal electroretinogram and visual evoked potential), associated with whole-body, head-down tilt. The subjects, ten per experiment, were visually normal with IOP less than 19. In the first experiment, IOP elevations were induced by varying the angle of tilt in discrete steps between +90 degrees (upright) and -90 degrees (inverted). In each position IOP was measured and significant elevations (up to 3x baseline) were noted. These elevations were maintained for 1 min during which simultaneous retinal and cortical biopotentials were measured. In the second experiment, 6 degrees head-down tilt was maintained for 2 hr during which time the IOP and both biopotentials were measured repeatedly. Our findings confirm the effect of body position of IOP, while also revealing that head-down tilt produces significant reductions in neurophysiological function at both the retinal and cortical levels. The neural effect is maximized when 6 degrees head-down tilt is maintained for 20 min.

Adult↗
PubMed1977

A therapeutic trial of vitamin A in patients with pigmentary retinal degenerations: a negative study.

A prospective therapeutic trial was designed to test the hypothesis that measurable improvement of retinal functions might occur in some patients with pigmentary retinal degeneration when placed on high doses of solubilized vitamin A (Aquasol A, 50,000 I.U. per day by mouth for 28 days). After a standard ophthalmic history and examination pre-trial examinations consisting of visual acuity, visual fields, color vision tests, dark adaptations and cone thresholds were obtained on two separate occasions. Electroretinography was usually performed only once. Forty-seven patients were entered into the study of which 27 had typical retinitis pigmentosa. The patients showed no significant change in visual function from pre-trial results when tested after taking the vitamin A for 28 days. Post-trial electroretinography performed on 10 patients with recordable pre-trial electroretinograms showed no change. The 10 patients retested at six and 12 months after the trial showed no significant change in visual function.

Adolescent↗