Search PubMed⌕ Search

Biomedical subjects

B Long

Publications and source records attributed to B Long.

At least 19 recordsLinked to original sources
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↗
PubMed1977

[Study of folic acid blood levels during estro-progestagen treatments].

When the blood levels of folates were estimated in 100 women following treatment with oestro-progestagens the following facts emerged : 1) There is no significant difference between the folate levels found in women on oestro-progestagens compared with a control population of the same age. 2) We have not found any evidence of frank folic acid deficiency in women on oestro-progestagens, but there have been slight drops in the levels of folates in women who show other reasons for folic acid deficiency than taking oral contraceptives. These are : troubles in absorption, salmonella, an increase in the need for folic acid in pregnancy, and failure of transport. Furthermore the incidence of lower levels in the control population was exactly the same as in the experimental population.

Contraceptives, Oral↗
PubMed1976

Direct association of messenger RNA labeled in the presence of fluoroorotate with membranes of the endoplasmic reticulum in rat liver.

Liver rough endoplasmic reticulum (RER) membranes were isolated from rats given [3H]orotic acid for 48 h (ribosomal RNA [rRNA] label) or for 3 h along with 5-fluoroorotate; this latter procedure permits the labeling of cytoplasmic messenger RNAs (mRNAs) in the absence of rRNA labeling. More than 50% of the labeled mRNA remained attached to membranes of the RER after complete removal of ribosomes with a buffer of high ionic strength in the presence of puromycin. Under similar conditions, membranes retained 40% of their polyadenylate as determined by a [3H]-polyuridylate hybridization assay. Treatment of mRNA-labeled endoplasmic reticulum membranes with pancreatic RNase indicates that the polyadenylate and possibly nonpolyadenylate-pyrimidine portions of the messenger are involved in the binding of mRNA to the membranes. The implication of these results in furthering our understanding of the mechanisms of the translational regulation of genetic expression is discussed.

Animals↗
PubMed1969

Sleep.

Explore the source record for details and available documents.

Circadian Rhythm↗
PubMedDate not supplied

Percutaneous feeding tube method for use in children.

Surgical gastrostomy has been a widely accepted method for introducing a percutaneous feeding tube for many years. However, complications are frequent, and many children who need them are not good surgical candidates. This study examines imaging guided percutaneous placement of feeding gastrostomy catheters as a safe and effective alternative to surgery.

Barium Sulfate↗