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Biomedical subjects

B Long

Publications and source records attributed to B Long.

At least 37 records · Page 2Linked to original sources
PubMed1993

Genes for interleukin 7 are transcribed in leukemic cell subsets of individuals with chronic lymphocytic leukemia.

Regulation of expression of interleukin 7 (IL-7) mRNA is aberrant in the leukemic subset of cells of chronic lymphocytic leukemia (CLL) patients. The entire coding sequence for IL-7 as well as an alternatively spliced IL-7 mRNA are transcribed in these leukemic cells. No IL-7 mRNA expression is detected in fresh peripheral blood mononuclear cells from normal individuals. Furthermore, the "normal" nonleukemic subsets of cells isolated from the same CLL patients also do not express IL-7 mRNA. The only subset of cells in which IL-7 mRNA is detected is the one that contains the leukemic cells themselves. The polymerase chain reaction was used to examine cytokine expression, and flow cytometry was used to purify the various subsets of peripheral blood mononuclear cells examined in these studies, as well as to examine IL-7 receptor expression. A proportion of the cells from the CLL patients express receptors that are capable of binding IL-7, whereas T cell-depleted normal cell preparations do not express receptors for IL-7 that are detectable with IL-7 fluorokines. The IL-7 receptor-bearing cells in CLL patients include a portion of leukemic cells and a fraction of the T cells, as well as some non-T, non-B cells. These findings suggest that IL-7 and IL-7 receptor expression in CLL may be relevant not only to growth regulation of the leukemic cells but to the immunological abnormalities that occur in the disease as well, possibly via the induction of inappropriate immune activity of IL-7 receptor-bearing cells.

Adult↗
PubMed1993

Phosphor plate computed radiography: response to variation in mAs at fixed kVp in an animal model. Potential role in neonatal imaging.

Computed digital radiography offers a number of potential advantages over conventional film-screen imaging. To determine the applicability of these to portable neonatal examinations we performed a controlled prospective study comparing conventional 200 speed film-screen with a computed radiography unit in an animal model. Images acceptable for diagnostic purposes were obtained on the digital system over an exposure range many orders of magnitude greater than was possible on the film-screen system. Digital imaging offers potential for elimination of repeat examinations due to suboptimal exposure factors, and for reduction in radiation dose to the patient. We believe that computed digital radiography should be particularly suited to portable neonatal imaging.

Animals↗
PubMed1993

The science of prevention. A conceptual framework and some directions for a national research program.

A conceptual framework for studying the prevention of human dysfunction is offered. On the basis of recent advances in research on the development of psychological disorders and methods of preventive intervention, generalizations about the relation of risk and protective factors to disorder are put forward, along with a set of principles for what may be identified as the science of prevention. Emerging themes from the study of human development, in general, need to be incorporated in the models for explaining and preventing serious problems of human adaptation. The article concludes with a set of recommendations for a national prevention research agenda.

Humans↗
PubMed1992

Comparison of computerized digital and film-screen radiography: response to variation in imaging kVp.

A controlled prospective study, in an animal model chosen to simulate portable neonatal radiography, was performed to compare the response of the Philips Computed Radiography (CR) system and conventional 200 speed film-screen (FS) to variation in imaging kVp. Acceptable images were obtained on the CR system over a very wide kVp range. In contrast the FS system produced acceptable images over a narrow kVp range. This ability suggests that the CR system should eliminate the need for repeat examinations in cases where a suboptimal kVp setting would have resulted in an unacceptable FS image. CR technology should therefore be ideally suited to portable radiography especially in situations where selection of correct exposure factors is difficult as in the neonatal nursery.

Animals↗
PubMed1992

Changes in epidermal growth factor receptor expression and response to ligand associated with acquired tamoxifen resistance or oestrogen independence in the ZR-75-1 human breast cancer cell line.

We have examined the expression of receptors for epidermal growth factor (EGFR) by the ZR-75-1 human breast cancer cell line and tamoxifen resistant (ZR-75-9al 8 microM) and oestrogen independent/tamoxifen sensitive (ZR-PR-LT) variants. The parent line expressed a single class of high affinity binding sites (4,340 +/- 460 receptors/cell; Kd 0.23 +/- 0.04 nM). ZR-75-9al 8 microM cells, routinely maintained in medium containing 8 microM tamoxifen, were negative for oestrogen receptor (ER) and progesterone receptor (PGR) and expressed a markedly increased number of EGFR (14,723 +/- 2116 receptors/cell). Receptor affinity was unchanged. Time dependent reversal of the tamoxifen resistant phenotype was accompanied by a return to ER and PGR positivity and a fall in EGFR numbers to parent cell levels. In contrast ZR-PR-LT cells had a greatly reduced EGFR content (803 +/- 161 receptors/cell) accompanying elevated PGR numbers. Pre-treatment of these cells with suramin or mild acid stripping failed to expose receptors which may have been occupied by endogenously produced ligand. Increased proliferation of ZR-75-1 cells treated with EGFR (0.01-10 ng ml-1) was only observed in serum-free medium lacking insulin and oestradiol. Under these conditions untreated cells failed to proliferate. Both variant lines continued to proliferate in serum free medium in the absence or presence of insulin and oestradiol but failed to respond to exogenous EGF.

Breast Neoplasms↗
PubMed1991

Digital imaging with a photostimulable phosphor in the chest of newborns.

To evaluate use of a digital photostimulable phosphor imaging system in the neonatal nursery, 150 newborns were divided into three groups of 50. In the first two groups, screen-film and computed radiographs of the chest were obtained at the same radiation exposure; in the third group, computed radiographs were obtained with a 50% dose reduction (half-exposure computed radiographs). All images were blindly evaluated by three readers who scored the quality of visualization of the mediastinum, lung, bone, soft tissues, and endotracheal and nasogastric tubes, and also image density. No statistical differences in visualization of tubes existed among the three groups. Visualization of the mediastinum, lung, bones, and soft tissues was statistically significantly better on computed radiographs than on half-exposure computed radiographs; visualization of the lungs, bones, and soft tissues was statistically significantly better on screen-film radiographs than half-exposure computed radiographs. Image density was statistically better on computed and half-exposure computed radiographs than on screen-film radiographs.

Humans↗
PubMed1989

Digital imaging of the newborn chest.

The study reports initial experience on utilising an area plate digital imaging system to obtain portable radiographic images on newborn infants. Initial results suggest that the system is a practical alternative to conventional portable radiography with potential advantages of decreasing the number of retake films and also of decreasing radiation dose.

Algorithms↗
PubMed1984

Heterogeneity of human colon carcinoma.

In order to better understand colon cancer, a model system reflecting the heterogenous nature of this disease was developed and used in the development of new cytotoxic and non-cytotoxic therapeutic approaches. A large bank of colon carcinoma cell lines was established from primary human colon carcinomas and grouped based on their tumorigenicity in athymic mice, their growth rates in soft agarose and in tissue culture, and their secreted levels of carcinoembryonic antigen. These cell lines were later characterized based on cell surface proteins and antigens detected with antisera raised against a differentiated colon carcinoma cell line. Although these biochemical markers correlated with the biological classification of these cell lines, there was still extensive heterogeneity within each group in all properties examined. This colon carcinoma cell system was used to study natural vs. selected resistance to the anticancer drug mitomycin C (MMC). The differing IC50 values in vitro were reflected in the inhibition by MMC of xenograft growth in athymic mice. A new, more readily bioactivatable analogue of MMC was tried and shown to be more active in vitro and in vivo, suggesting that rapid efflux of the drug before activation may be important in examining causes of resistance to MMC. Another approach to the treatment of colon cancer is the use of non-cytotoxic agents such as growth factors and differentiation agents to restore normal growth to the malignant cells. We have isolated and characterized two types of polypeptides from colon carcinoma cells and conditioned medium from these cells. The first, transforming growth factors (TGF's) confer a transformed phenotype on non-transformed fibroblasts while the second, tumor inhibitory factors (TIF's), inhibits the anchorage independent growth of transformed cells. The fact that extracts of colon carcinoma cells contain both activities suggests that the heterogeneity of the cell lines could be due to different levels of TGF's and TIF's produced. The effectiveness of differentiation agents to restore normal growth control using a transformed mouse embryo cell line was examined. Treatment of these cells with differentiation agents restored normal growth control to these cells. An increased synthesis of TGF's resulted from these treatments. Therefore, differentiation agents may be useful in non-cytotoxic treatment. The use of this model system for human colon carcinoma will hopefully lead to more effective drugs for the treatment of colon cancer in man.

Animals↗
PubMed1980

Low-dose captopril in chronic heart failure: acute haemodynamic effects and long-term treatment.

The acute haemodynamic effects of low doses of the oral converting-enzyme inhibitor, captopril, were studied in 18 patients with severe chronic heart failure. The effects of long-term therapy were also evaluated. Increasing doses (1 mg, 2.5 mg, 6.25 mg, 12.5 mg, and 25 mg) of captopril were given at 2 h intervals with haemodynamic monitoring. Graded haemodynamic improvement (increased stroke-volume index and reduced mean pulmonary capillary wedge pressure) was noted from 1 hand was closely associated with reduction of blood pressure. Maximal haemodynamic improvement for the group was seen at 6 h and 7 h after the 6.25 mg and 12.5 mg doses, when stroke-volume index had risen 35% and mean pulmonary capillary wedge pressure had fallen 40% from control. Captopril 12.5-50 mg every 8 h was continued long term but was withdrawn in 2 patients with symptomatic hypotension and 1 patient with altered taste. 4 patients died and 1 was noncompliant with therapy. At 3 months, 10 patients showed significant improvement in symptoms, treadmill-exercise duration, and echocardiographic indices of left-ventricular size and function. Repeat haemodynamic measurements were similar to optimum measurements obtained during the initial study.

Adult↗
PubMed1980

Antenatal plasma exchange therapy.

A 22-year-old primigravida with severe mesangiocapillary gomerulonephritis presented at 10 weeks gestation for antenatal care. Delivery of a small health infant was achieved by caesarean section at term. The successful outcome of this pregnancy was attributed to the careful control of anaemia, oedema, and hypertension; and to the use of plasma-exchange therapy throughout the third trimester. The value of plasma exchange therapy in pregnancies which are complicated by renal disease is discussed.

Adult↗