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Biomedical subjects

D Smith

Publications and source records attributed to D Smith.

At least 1,063 records · Page 59Linked to original sources
PubMed1983

Radioassay problems associated with the clinical use of a 82Rb radionuclide generator.

The short-lived positron emitting radionuclide 82Rb (t1/2 1.27 min) is conveniently available from a 82Sr/82Rb generator system. The parent nuclide (t1/2 25.5d) produced from the spallation of molybdenum, has associated with it varying quantities of other long-lived strontium radionuclides, namely 85Sr, 89Sr and 90Sr. It is important therefore in the clinical use of such material that the levels of strontium radionuclides being administered to patients is carefully assayed and controlled. The problems associated with these measurements are discussed with special reference to the radiation dose received by the patient and the problems in resolving overlapping peaks with different FWHMs.

Humans↗
PubMed1983

Treatment of skin graft donor sites with a semipermeable polyurethane dressing.

The use of a semipermeable dressing for skin graft donor sites has been described. It permits patients with healing donor sites to ambulate, shower, and wear clothing with no pain during the healing phase. Healing is easily monitored, and signs of infection can be detected early and treated promptly, preventing involvement of the full thickness of the wound. Patients can be discharged from the hospital while the donor site is still healing. The dressing can be removed painlessly at home or in the office. The SPD appears superior to any of the more conventional dressings currently in use for treating skin graft donor sites.

Female↗
PubMed1983

Water soluble vitamin requirements in home parenteral nutrition patients.

Ascorbic acid, thiamin, niacin, pyridoxine, and folic acid status was evaluated in eight physiologically stable home parenteral nutrition patients. Six of these subjects received these vitamins as a twice weekly bolus and were studied over a period of 6 days. All vitamin levels were normal except for blood thiamin which was low, 72 h after each bolus. Since transketolase levels remained normal, this fall in blood thiamin probably had no functional significance. The urine excretion pattern of niacin and pyridoxine indicated normal metabolism and retention of these vitamins. Two patients, who required only parenteral fluid and electrolytes to remain weight stable, received none of these vitamins parenterally, but also maintained adequate vitamin status. These results suggest that in long term home parenteral nutrition patients these five vitamins can safely be given twice weekly, rather than daily, and that short bowel patients who maintain their weight without intravenous calories and protein also assimilate adequate amounts of these proximally absorbed water soluble vitamins from their diet.

Adult↗
PubMed1983

Response to dexamethasone suppression and total night sleep deprivation in an affectively disordered Klinefelter patient.

A 50-year-old Klinefelter patient acutely developed a psychotic depression which rapidly responded to treatment with amitriptyline. This patient exhibited an early escape from dexamethasone suppression and became hypomanic the morning after total night sleep deprivation. The findings suggest that the use of biological tests to study affective syndromes occurring in Klinefelter patients might yield clues regarding the existence of pathophysiological common denominators of primary and Klinefelter-associated affective disorders.

Affective Disorders, Psychotic↗
PubMed1983

An evaluation of the Technicon H6000 haematology system.

The Technicon H6000 haematology system combines haemoglobinometry with cell counting including differential counts of leucocytes. Evaluation confirmed it to be safe, precise and free from carry-over of practical significance. Comparability with standard reference methods showed a difference with mean cell volume (MCV) and packed cell volume (PCV) but the haemoglobin, red cell count and mean haemoglobin concentration (MCH) were comparable. Total white cell counts and differential counts were comparable apart from eosinophils and basophils. Platelet counts were higher at both ends of the range. Throughput was confirmed at 90 samples per hour. The system was shown to be cost-effective when taking into consideration staff costs, materials and maintenance but expensive with regard to materials alone.

Autoanalysis↗
PubMed1983

Effect of ketoconazole and amphotericin B on encapsulated and non-encapsulated strains of Cryptococcus neoformans.

Growth inhibition studies were done on an encapsulated and non-encapsulated strain of Cryptococcus neoformans at the minimal inhibitory concentration and one-half the minimal inhibitory concentration of ketoconazole and amphotericin B alone and in combination. Growth of both strains was significantly inhibited by ketoconazole, amphotericin B, and the combined drugs at the minimal inhibitory concentration of each drug over a 5-day period. Calculation of the expected inhibition of growth for both strains with both drugs showed antagonism at 24 h followed by an additive effect and synergy for the remaining 4 days of the assay. Although similar results were obtained for both strains with one-half the minimal inhibitory concentration, an additive effect was observed with the drug combination at 24 h for the encapsulated strain, and an antagonistic effect was observed with the non-encapsulated strain.

Amphotericin B↗
PubMed1983

Production and characterization of monoclonal antibodies against avian retrovirus reverse transcriptase.

Monoclonal antibodies were prepared against the avian myeloblastosis virus reverse transcriptase. These monoclonal antibodies specifically immunoprecipitated the alpha and beta subunits of the reverse transcriptase molecule, as well as the Pr180gag-pol precursor protein present in virus-infected cells. In addition, these monoclonal antibodies inhibited the DNA polymerase activity associated with the reverse transcriptase molecule but not the RNase H activity. The monoclonal antibody preparations were specific for the amino-terminal portion of the protein, as determined by the immunoprecipitation of a reverse transcriptase-beta-galactosidase fusion protein produced in Escherichia coli by molecular cloning procedures.

Animals↗
PubMed1983

Origin of the third heart sound. I. Studies in dogs.

We studied 13 anesthetized dogs in which a third heart sound (S3) was repeatedly induced by hypoxemia plus fluid overload. A miniature accelerometer with a mass of about 1.1 g was applied at three levels--intact chest wall over cardiac apex, in the pericardium and on the epicardium--to record motion of the structures under observation as well as sound. Intraventricular pressure and sound were monitored using a Millar catheter. Application of two accelerometers simultaneously over the epicardium permitted observation of the chronologic sequence of ventricular wall dynamics in early diastole. The S3 at each level occurred simultaneously with the sudden onset of reduced acceleration, or negative jerk. These dynamic phenomena were maximal at or near the cardiac apex. We conclude that the event that triggers the S3 is a sudden intrinsic limitation of longitudinal expansion of the left ventricular wall.

Animals↗
PubMed1983

Origin of the third heart sound. II. Studies in human subjects.

We report noninvasive and invasive studies designed to clarify the mechanism of the third heart sound (S3) in humans. The noninvasive observations were made using a miniature accelerometer attached to the skin surface at the cardiac apex. In subjects with no S3, the tracings were either flat or showed very low undulations throughout diastole. Those with an S3, however, demonstrated a distinct reduction of acceleration, or negative jerk, of the rapid filling movement at the apex at the time of the sound. The invasive studies in the cardiac catheterization laboratory consisted of frame-by-frame measurements of left ventricular dimensions in the transverse and long axes during early diastole in patients with diastolic overload abnormalities to investigate the temporal sequence of filling in these two principal axes. The maximal long-axis filling rate occurred after the short axis, a finding that helps to resolve a discrepancy noted in the time of maximal short-axis filling and S3 production. These studies support the concept that the S3 is due to a sudden intrinsic limitation of longitudinal expansion of the left ventricular wall during early diastolic filling, resulting in a negative jerk that is transmitted to the skin surface.

Cineangiography↗
PubMed1983

Chest wall velocity and the second heart sound. An improved sensor of S2 splitting.

We report a new method of detection of the timing of the aortic and pulmonary valve closure that depends not on the registration of audible vibrations, but rather, on subtle but distinct movements of the chest wall, which are external manifestations of these events. We studied these phenomena in six open-chest dogs and in 69 human subjects. The dog studies show that the two distinct inward movements detected by a motion sensor applied to the epicardium in the vicinity of the right ventricular outflow tract correlate with the timing of the incisural notches of the pressure signals from the great vessels. In humans, these movements are transmitted to the skin surface and can be detected noninvasively. In 48 of the 69 human subjects (70%), these spikes provided a significantly better indication of the timing of semilunar valve closure than did the conventional phonocardiogram.

Animals↗
PubMed1983

Ovulation timing by luteinizing hormone assay and follicle puncture.

Follicle puncture with oocyte harvest or ovarian inspection for an early corpus luteum was carried out in 13 patients undergoing laparoscopy during routine infertility workup. Laparoscopies were carried out 28 to 38.5 hours after the onset of the luteinizing hormone surge so that there would be a concentration of data around the expected time of ovulation. A rapid luteinizing hormone assay was used. All the corpora lutea were found 38 hours or more after the onset of the luteinizing hormone surge. Between 28 and 38 hours after the onset of the surge, intact follicles containing oocytes in various stages of maturation were found.

Corpus Luteum↗
PubMed1983

Insulin action in uremia.

The evidence appears overwhelming that insulin resistance is the major cause of the carbohydrate intolerance observed in chronically uremic subjects and that the primary site of this insulin resistance resides in peripheral tissues, muscle. Diminished lipoprotein lipase activity, perhaps related to decreased insulin sensitivity, is in large part responsible for the hypertriglyceridemia. However, there is some evidence that increased VLDL synthesis also contributes to the disturbance in lipid metabolism. This latter abnormality may be related to the high circulating insulin levels that result from the insulin resistance. In contrast to glucose and lipid metabolism, the plasma amino acid and potassium lowering effects of insulin are normal in uremic individuals. Whether there is an impaired ability of insulin to stimulate protein synthesis and inhibit protein degradation remains to be delineated.

Adult↗
PubMed1983

Fate of a second porcine bioprosthetic valve.

Since October, 1971, 744 porcine bioprosthetic valves were inserted in patients discharged from the hospital and were therefore at risk for primary valve failure or tissue degeneration. In this period of time, 41 valves have demonstrated spontaneous degeneration. The percentages of valve survival without degeneration are as follows: at 6 yeras, 93% +/- 1.5% (SE); 7 years, 88% +/- 2.0%; 8 years, 82% +/- 2.9%; 9 years, 80% +/- 3.4%. The incidence of degeneration appears to be decreasing even though the total number of valves at risk is increasing each year. Of the 41 valves removed for spontaneous degeneration, 25 valves in 24 patients have been replaced by a second bioprosthesis. These 24 patients have been followed up for from 2 to 61 months, and there has been no clinical evidence of degeneration of the second bioprosthesis. One patient has had a second bioprosthesis longer than the first. Although others have suggested that degeneration may be immunologic event, our experience suggests that there is no "second set" rejection. The absence of a "second set" rejection and the suggestion of a decreasing incidence of degeneration makes us continue to favor the bioprosthesis for primary and secondary valve replacement.

Actuarial Analysis↗
PubMed1983

Wernicke's encephalopathy: a predictable complication of hyperemesis gravidarum.

Wernicke's encephalopathy occurred during prolonged intravenous feeding in two patients with hyperemesis gravidarum. Delay in diagnosis caused a protracted illness and persisting neurologic deficits in both patients. Because of its association with chronic alcoholism, the possibility of Wernicke's encephalopathy may not be considered early enough, if at all, in other situations; it is too frequently not discovered until postmortem examination. The disease may complicate other neurologic disorders due to nutritional deficiency, but can be prevented by the timely administration of parenteral thiamine.

Adult↗