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Biomedical subjects

S Greenbaum

Publications and source records attributed to S Greenbaum.

10 recordsLinked to original sources
PubMed2000

A genetic investigation of E2A function in lymphocyte development.

Lymphocytes are derived from hematopoietic stem cells (HSC) following a series of regulated differentiation events. Multipotent HSCs become committed to the B cell lineage in bone marrow and the T cell lineage in the thymus after receiving appropriate signals from the corresponding microenvironment. These committed lymphoid cells must then undergo V(D)J recombination at the immunoglobulin gene or T cell receptor gene locus resulting in clonal production of functional B or T lymphocytes, respectively. Lymphocyte commitment and differentiation are accompanied by programmed gene expression or repression events which are driven by lineage and stage specific transcription factors. The basic-helix-loop-helix (bHLH) transcription factors encoded by the E2A gene are involved in several differentiation events during B and T cell development, including lineage commitment, initiation of V(D)J recombination, and antigen receptor mediated proliferation and differentiation. Several recent reviews have provided a comprehensive discussion of biochemical, cellular, and genetic research on E2A function in lymphocyte development (1,2). Here, we only discuss some of the genetic approaches our laboratory (except where it is noted) has undertaken to investigate the molecular pathways mediated by E2A transcription factors in lymphocyte development.

Animals↗
PubMed1997

Bispecific monoclonal antibody complexes facilitate erythrocyte binding and liver clearance of a prototype particulate pathogen in a monkey model.

We used Anger camera imaging in a monkey model to investigate the organ localization of a prototype particulate pathogen, 131I-labeled bacteriophage phi X174, after it was bound to the primate erythrocyte complement receptor and then cleared from the circulation. This 131I-labeled phi X174 was infused into the circulation of an immunized monkey, and the nascently formed immune complexes showed rapid and quantitative binding to erythrocytes via the immune adherence reaction (complement-mediated binding). Alternatively, phi X174 was infused into the circulation of a naive animal, and then cross-linked bispecific mAb complexes (heteropolymers, anti-CR1 x anti-phi X174) were infused into the circulation. The infused heteropolymers also facilitated rapid and quantitative binding of phi X174 to erythrocytes. In both cases, after a short lag period, the erythrocyte-bound phi X174 was rapidly cleared from the circulation, and the vast majority of the radiolabel was cleared to the liver, with a small amount clearing to the spleen. Further liver imaging confirmed that within 24 h most of the bacteriophage previously cleared to the liver via the heteropolymer system was phagocytosed and destroyed. The findings in this model system provide additional evidence for the potential utility of heteropolymers to facilitate the safe and rapid clearance of blood-borne pathogens as a potential treatment for infectious diseases.

Animals↗
PubMed1995

Performance of Americans and israelis with cerebrovascular accident on the Loewenstein Occupational Therapy Cognitive Assessment (LOTCA).

OBJECTIVE: The Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) measures the cognitive performance of persons with cerebrovascular accident (CVA). Although this assessment was developed and standardized in Israel, it is frequently used in the United States. The purpose of this study was to identify whether differences in performance on the LOTCA existed between Americans and Israelis who have had strokes. Additionally, this study was designed to compare the performance of persons with right CVA with the performance of persons with left CVA because the normative data for the LOTCA does not include separate information for these two groups. METHOD: The LOTCA was administered to 25 Americans with CVA (19 right CVA and 6 left CVA) and 56 Israelis with CVA (26 right CVA and 30 left CVA). RESULTS: On the majority of LOTCA subtests, there were no significant differences between American and Israeli subjects. Only one subtest, Orientation to Time, revealed significant differences between Americans and Israeli subjects both for subjects with right CVA and subjects with left CVA. Examination of subjects with right CVA versus subjects with left CVA also indicated few differences. Only one subtest, Pegboard Construction, revealed significant differences between subjects with right CVA and subjects with left CVA for both American and Israeli subjects. CONCLUSION: The LOTCA is an appropriate tool for occupational therapists to use in assessing Americans who have had strokes. In addition, for the most part, the subtests of the LOTCA assess cognitive-perceptual abilities that are not specific to the right or left cerebral hemisphere.

Aged↗
PubMed1995

Treatment of recalcitrant warts using the pulsed dye laser.

Recalcitrant warts are a common therapeutic problem. We used the 585 nm pulsed dye laser to treat flat, common, plantar/palmar, and periungual warts that had failed to respond to keratolytic or destructive therapy. Flat warts were most responsive, but all wart types had a significant response to this benign treatment modality.

Humans↗
PubMed1993

Decorin, versican, and biglycan gene expression by keloid and normal dermal fibroblasts: differential regulation by basic fibroblast growth factor.

Basic fibroblast growth factor (bFGF) is a multipotential heparin-binding factor that belongs to the fibroblast growth factor (FGF) family. The FGFs demonstrate a wide spectrum of biologic activities in vivo and in vitro. In this study, we investigated the potential of bFGF to regulate the expression of various dermal extracellular matrix proteoglycans and type I collagen mRNAs in cultured human fibroblasts from keloid, which is a prototype of dermal fibrosis, and normal skin tissue. We report that bFGF upregulates the expression of the decorin gene in normal and keloid fibroblasts. In contrast, the expression of biglycan is downregulated by bFGF. The mRNA steady-state level of versican, a large proteoglycan, is not altered by bFGF. Type I collagen gene expression is downregulated substantially in keloid and normal fibroblasts by bFGF. The results suggest that the expression of the proteoglycan genes are uncoordinately regulated and that the gene expression of type I collagen and biglycan is coordinately downregulated. The results also demonstrate that keloid fibroblasts respond similarly as do normal fibroblasts to bFGF in the regulation of proteoglycan and collagen expression.

Biglycan↗
PubMed1993

Reading in pure alexia. The effect of strategy.

A number of investigators have demonstrated that patients with pure alexia comprehend briefly presented words which they are unable to explicitly identify. We suggested previously that these patients may read by means of two distinct procedures: a laborious letter-by-letter method and a 'whole-word' procedure which, at least initially, does not support explicit word identification. We report a test of this proposal in a patient with pure alexia. We reasoned that if the patient had access to two distinct and incompatible procedures, he might be induced to switch from one to the other by changing task demands. We found that when instructed to name words, the patient employed a letter-by-letter strategy; in contrast, when instructed to make lexical decision or semantic judgements about rapidly presented words, he appeared to use a 'whole-word' strategy. These data support the hypothesis that two distinct procedures are available to this patient. We argue, further, that is necessary to suppress use of the letter-by-letter strategy to demonstrate whole word reading capability in pure alexics, and that failure to do so may account for negative findings in other cases reported in the literature.

Cerebral Infarction↗
PubMed1988

Eye-sighting preference of normal and hemiplegic children and adults.

Monocular eye-sighting preference was examined in 32 children with hemiplegia, 51 adult-onset hemiplegic patients and 57 normal children and adults. Eye preference was compared with ear preference on dichotic listening for 25 of the hemiplegic children. No independent association could be detected between eye preference and ear preference. In both the children and adults with hemiplegia the preferred eye tended to be on the same side as the damaged hemisphere. Among the adults, this tendency was more pronounced with more extensive lesions, as manifested by aphasia and/or hemianopia. These findings are interpreted as indicating that eye-sighting preference is unrelated to unitary hemispheric dominance, and that, unlike dominance for hearing and speech, it is not irreversible after a critical period of development. A simpler explanation than incomplete hemispheric dominance is offered for the weakly positive association between mixed laterality and cerebral dysfunction.

Adult↗
PubMed1985

The optically determined corneal and anterior chamber volumes of the cynomolgus monkey.

We described an optical method of measuring corneal volume and employed the optical method of Johnson et al. for measuring the volume of the anterior chamber in cynomolgus monkey. In 12 normal monkey eyes, the corneal volume was found to be 40.4 +/- 2.3 microliter (mean +/- S.E.) and the anterior chamber volume was 101.8 +/- 4.2 microliter (mean +/- S.E.).

Animals↗