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Biomedical subjects

R H Morgan

Publications and source records attributed to R H Morgan.

At least 37 records · Page 2Linked to original sources
PubMed1987

Nifedipine in patients with Raynaud's syndrome--effects on radial artery blood flow.

The acute effect of nifedipine on hand blood flow of 20 patients with Raynaud's phenomenon, treated in a double-blind, crossover study, is reported. Radial artery blood flow was found to correlate with the reciprocal of the pulsatility index. This simple Doppler technique gave an instantaneous record of the effect of cooling on hand blood flow. In patients with Raynaud's phenomenon, nifedipine prevents the reduction of hand blood flow that is induced by cooling in untreated patients.

Administration, Sublingual↗
PubMed1987

The effects of nifedipine on blood flow in peripheral vascular disease of the lower limbs.

The effects of nifedipine on blood flow to the lower limb have been investigated in 19 patients with calf claudication, and in 8 patients with critical leg ischaemia, using Doppler techniques. In claudicants, common femoral artery blood flow increased by 55% after sublingual nifedipine, despite a fall in systolic blood pressure and no alteration in the ankle/brachial index. In patients with critical ischaemia given intravenous nifedipine, common femoral blood flow increased to reach a peak 90 minutes after the start of the infusion. The femoral artery pulsatility index, derived from the Doppler waveform, is a reliable guide to changes in blood volume flow.

Administration, Sublingual↗
PubMed1983

Isolation of cell lines from differentiating embryonal carcinoma cultures.

We report the isolation of six cell lines (designated EB cell lines) from cultures of the hypoxanthine guanine phosphoribosyl transferase-deficient (HGPRT-) feeder-dependent embryonal carcinoma cell line PSA4TG12 which have undergone in vitro differentiation, and of clonal derivatives of these lines. Whereas some lines possess quasi-diploid karyotypes similar to that of PSA4TG12, others are markedly aneuploid. Cell line EB26/1 and its clonal derivatives undergo adipogenesis in cultures maintained at confluence; in tumours formed by injection into syngeneic mice they produce muscle-like cells, cartilage and bone in addition to adipose cells. We therefore propose that EB26/1 and its clones are aneuploid derivatives of an uncommitted mesodermal cell. Cell line EB28/5 forms tumours with a histological appearance resembling that of yolk sac carcinoma but does not express biochemical markers characteristic of visceral or parietal endoderm. Cell line EB28/10n has a myoblast-like culture morphology and in tumours is capable of producing muscle-like cells, cartilage and bone. A high specific activity of alkaline phosphatase is present is two of five EB cell lines assayed, and plasminogen activator activity is present in all five. Since the EB cell lines represent populations of cells each expressing a particular subset of the genetic information present in a common ancestral genome, they will be invaluable for studying the developmental regulation of gene expression.

Alkaline Phosphatase↗
PubMed1982

Factors influencing quantitative CT measurements of solitary pulmonary nodules.

Quantitative computed tomographic (CT) measurement of pulmonary nodules has not been widely applied despite favorable reports. Its usefulness has been questioned by some investigators. A series of experiments on six different scanners was undertaken to study the factors that affect the applicability of this technique. The type of reconstruction algorithm, the design of the CT system, the true slice thickness, and the beam kilovoltage were the most important factors identified. These factors can produce large variations in the CT numbers of pulmonary nodules, preventing direct comparison of results from scanner to scanner. Before undertaking studies of pulmonary nodules, the effect of these variables in each individual scanner should be evaluated. Despite the current lack of standardization, reliable CT number measurements using a specific kilovoltage and slice thickness should be possible on every modern scanner provided it is positionally uniform and gives a linear response to varying densities. We propose that the CT number above which a pulmonary nodule can be considered benign should be the representative CT number of a 1 cm diameter syringe filled with a hydrous calcium chloride solution of 40 mg/ml of water and scanned in air. A better understanding of the physics of lung nodule densitometry is necessary for the proper application of this technique in the management of patients with solitary pulmonary nodules.

Evaluation Studies as Topic↗
PubMed1979

Proficiency examination of physicians for classifying pneumoconiosis chest films.

An examination has been developed to test the proficiency of physicians classifying chest radiographs with pneumoconiosis in accordance with the classification system promulgated by the International Labor Office in Geneva. The examination, prepared by Johns Hopkins University under contract with the National Institute of Occupational Safety and Health, was commissioned to identify physicians qualified to serve in national pneumoconiosis programs directed both to epidemiological research and to the compensation of coal miners and others who suffer from dust-related illness. The examination, consisting of 125 chest radiographs, includes examples of a broad range of disease extending from normal to far advanced pneumoconiosis. An examinee passes or fails by ability to classify the films, within prescribed limits, in the same manner as an expert panel of radiologists. The examination is open to radiologists, chest physicians, occupational health specialists, and other physicians interested in pneumoconiosis. By the end of 1978, the examination had been given to 202 candidates, including 116 radiologists 30 chest physicians, three candidates certified in preventive medicine, two family practitioners, and 51 others. Of the 202 candidates, 118 (58.4%) passed and 84 (41.6%) failed. Among the candidates taking the examination for the first time, 74 radiologists (63.8%) and 18 chest physicians (60%) received passing grades. Of the remainder, 21 physicians (37.5%) were successful. Early experience indicates the examination is quite successful in meeting its primary objectives, which suggests that this type of examination may be applicable in other situations to separate those who meet certain standards of performance in radiology from those who do not.

Clinical Competence↗