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Biomedical subjects

M Powell

Publications and source records attributed to M Powell.

At least 163 records · Page 9Linked to original sources
PubMed1987

Spine and femur density using dual-photon absorptiometry in US white women.

Bone mineral density (BMD) of the spine (n = 892) and femur (n = 634) was measured using dual-photon absorptiometry in normal white women from seven diverse locations. The same model commercial scanner with a 153Gd source was used in all locations (SD = 1.3% among locations). There was not an age-associated decrease of spinal BMD during young adulthood (20-40 years); the correlation of age and femoral BMD in this period was low but significant (r = -0.21). There was a narrow range of intra-population variation at all ages (10-12%). The cross-sectional data showed an average diminution of about 20% in the spine and 25% in the femur between 40 and 70 years of age, followed by a continued but slower, decrease of density in older women. Adjustment of values for height and weight was called for mainly at extremes of body size.

Aging↗
PubMed1986

Epitope analysis of monoclonal antibody NCRC-11 defined antigen isolated from human ovarian and breast carcinomas.

NCRC-11 is an IgM monoclonal antibody which defines an antigen found in most epithelial malignancies. The antigen has previously been shown to be a high mol. wt. glycoprotein (greater than 400,000) and in this study, antigen preparations were isolated by immunoadsorbent chromatography from ovarian mucinous and ovarian serous cyst adenocarcinoma and from breast carcinoma. Other monoclonal antibodies, against products in normal human milk, and antibodies of the Ca series (Bramwell et al., 1985) reacted with all three antigen preparations. Tests involving epitope mapping were performed to probe the relationships of the various epitopes to that defined by the NCRC-11 antibody, and, of note, the three antigen preparations from different tumour sources were remarkably similar with respect to their relative levels of epitope expression and to their topographical distribution of epitopes. The major differences in epitope expression could be attributed to the degree of sialylation in the three antigens. The antigens from ovarian tumours expressed I(Ma) blood group determinants (defined by the antibody LICR-LON-M18) which were partially masked by sialic acid. With NCRC-11 defined antigen from breast carcinoma, this determinant was totally masked by sialic acid although neuraminidase treatment clearly exposed epitopes reactive with M18 antibodies.

Antibodies, Monoclonal↗
PubMed1986

Studies on cerebral oxygen metabolism, blood flow, and blood volume, in patients with hydrocephalus before and after surgical decompression, using positron emission tomography.

Cortical oxygen utilization, oxygen extraction, blood flow, and blood volume, have been measured in patients with hydrocephalus before and after surgical decompression using positron emission tomography (PET). The hydrocephalus subjects fell into two categories: patients with recent-onset obstructive hydrocephalus and symptoms of raised intracranial pressure due to obstruction of cerebrospinal fluid (CSF) drainage by posterior fossa or third ventricular cerebral tumours, and patients with hydrocephalus of more insidious onset that was associated either with congenital abnormalities, or which was idiopathic. The hydrocephalus subjects had a significantly reduced level of mean cortical oxygen utilization (rCMRO2) and mean cortical blood flow (rCBF) compared with age-matched normal controls. Patients with recent-onset obstructive hydrocephalus associated with cerebral neoplasia had inappropriately low levels of cortical blood flow compared with their levels of cortical oxygen utilization, all having elevated levels of cortical oxygen extraction (rOER). Levels of cortical blood flow in the group of patients with more insidious-onset hydrocephalus matched levels of cortical rCMRO2, all these subjects having normal levels of rOER. All those hydrocephalus subjects who had a raised cortical oxygen extraction preoperatively increased their cortical blood flow following cerebral decompression. No improvement, however, was noted in their mean cortical oxygen utilization. By contrast, those hydrocephalus subjects with normal baseline levels of cortical extraction showed no improvement in mean cortical blood flow, oxygen utilization, or cognitive function after surgical intervention. It is concluded that if cortical oxygen extraction is elevated, hydrocephalic patients are likely to improve their cortical blood flow following cerebral decompression.

Adult↗
PubMed1985

Life skill training: psychoeducational training as mental health treatment.

Fifty-four patients of a Veterans Administration Medical Center were assigned to either a life-skill training program that emphasized psychoeducational instruction and skill building or to a group counseling control condition. Subjects assigned to life-skill training were provided with 28 hours of instruction in interpersonal communication, purpose in life problem solving, and physical fitness/health maintenance. Control subjects received equal time engaged in psychiatric treatment that emphasized the analysis and exploration of personal problems, but with no direct coping skill training. Significant differences between the two groups were found on measures of interpersonal communication and meaningful purpose in life. Both groups received lower staff ratings on psychopathological behavior and demonstrated improvement on ratings of health and physical fitness upon completion of treatment. Twelve- and 24-month follow-up data that include rehospitalization rates are presented for each group.

Adaptation, Psychological↗
PubMed1985

Adrenergic stimulation of prostacyclin production in the rat tail artery. I. Response to agonists and antagonists.

The release of prostacyclin (PGI2) as measured by the production of 6-keto-PGF1 alpha was assessed in vitro in rat tail artery segments after exposure to norepinephrine (NE). Time course studies demonstrated a three fold increase in 6-keto-PGF1 alpha production in response to 6 X 10(-5) M NE that persisted for approximately one hour. This production was almost completely prevented by the cyclooxygenase inhibitors indomethacin and ibuprofen and the phospholipase inhibitor mepacrine. Vigorous rubbing of the vessel intima did not prevent the response to NE. Previously stimulated tissues were unresponsive to further addition of NE. However, the addition of arachidonic acid following NE resulted in further increases in PGI2 production which exceeded that of the addition of arachidonic acid alone. NE stimulation was significantly inhibited by phentolamine and prazosin pretreatment of the tissues but was not affected by yohimbine or propranolol. Alpha-1 adrenergic agonists (cirazoline, methoxamine, and phenylephrine) were stimulatory whereas alpha-2 agonists in high doses (tramazoline, BHT-920, xylazine, and UK-14304) were without effect. It is concluded that norepinephrine stimulates PGI2 production in the rat tail artery via an alpha-1 adrenergic receptor. NE also enhances the conversion of arachidonic acid to PGI2. Exhaustion of the response appears to be due to consumption of available arachidonic acid. The fact that procedures which generally remove most of the endothelium did not prevent NE-induced stimulation points to the vascular smooth muscle as the likely source of adrenergically mediated prostacyclin generation in this tissue.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Depression: a breakdown of perceptual defence?

The effect of depressed mood on the tachistoscopic recognition of neutral/unpleasant words was investigated in a group of 18 depressed inpatients and in 17 normal controls. A 50% recognition threshold for 30 neutral words was calculated for each subject, in order to exclude the effects of depressive slowness on the experimental task. Each subject was tachistoscopically presented with a series of experimental words (30 neutral/30 unpleasant) at his 50% level, and the ratio of neutral to unpleasant words recognised calculated. Depressed subjects tended to recognise a higher ratio of unpleasant to neutral words.

Adult↗
PubMed1983

Phase I study of MVE-2 therapy in human cancer.

MVE-2, a polymer of maleic anhydride and divinyl-ether (molecular weight, 15,500), was given to 57 patients in a phase I study. The agent was selected for study because it was a potent macrophage activator, interferon inducer, and immunotherapeutic agent in animal tumor models. The drug was administered by iv infusion over a 1-hour period using three schedules of administration: (a) weekly at doses of 25-650 mg/m2, (b) every other week at doses of 500-1200 mg/m2, and (c) every 3 weeks at doses of 1200-1500 mg/m2. No cardiac, pulmonary, hematologic, or hepatic toxicity was observed. There were 25 episodes of asymptomatic proteinuria in 26 patients who received MVE-2 dose levels of greater than or equal to 500 mg/m2. It was not associated with changes in BUN or creatinine. The proteinuria began approximately 4 weeks after the start of therapy and lasted approximately 4-6 weeks after the therapy was terminated. Proteinuria resolved in all patients followed. At present, proteinuria appears to be the major dose-limiting toxicity. None of the patients had a partial or complete response although there was evidence of biologic activity with measurable tumor regression in five patients. No major modification of host defense parameters was noted. Further studies should be directed towards determining the nature of the proteinuria and whether changes in the rate or schedule of administration can modify the proteinuria or increase the host defense modification.

Blood Urea Nitrogen↗
PubMed1981

Deadtime measurements with a multihole phantom: concise communication.

The performance characteristics of any Anger camera are defined by that camera's spatial and temoral resolutions. Procedures using first-past techniques--such as ejection fraction or left-to-right shunt determinations--require that deadtimes be minimal. We have evaluated a simplified method for measuring a camera's deadtime; it uses a multihole phantom consisting of a lead sheet with 196 holes, 7/16 in. diameter, arranged in a 14 X 14 matrix. Each hole can be filled with a removable lead plug. Count rates are determined following incremental removal of the plugs. Deadtime curves were generated for each of three cameras by this and standard techniques. For each camera, the three curves were virtually identical. Using the phantom, deadtimes could be determined in 15 to 20 min. This phantom provides a simple, rapid, and accurate means of determining camera deadtime and minimizing personnel radiation exposure.

Models, Structural↗
PubMed1980

Documenting the value of supervised play in a pediatric ambulatory care clinic.

This study tested the hypothesis that supervision of play in a pediatric ambulatory clinic would increase positive resonses and decrease negative responses in outpatients. During the control week, children played unsupervised in the unaltered clinic waiting area; selected behaviors were recorded then and during the experimental week, in which changes introduced in the clinical environment facilitated supervised play. Significant increases in positive responses and significant decreases in negative responses were noted during the experimental week (X2=474.4; p. <. 001.). A second study demonstrated that significant changes were not caused by environment alteration alone. The resultant outpatient program and its benefits are described.

Child↗
PubMed1978

Isolation and characterization of a novel fucoganglioside of human erythrocyte membranes.

A slow migrating monosialosyl ganglioside with blood group H activity was isolated from human erythrocyte membranes and identified as monosialosylceramide decasaccharide. Its structure was determined by degradation with exo- and endoglycosidases, by mass spectrometric characterization of a nonasaccharide liberated by endo-beta-galactosidase, and by methylation analysis and mass spectrometry of permethylated glycolipids before and after enzymatic degradation. The ganglioside contains two oligosaccharide chains branched through GlcNAcbeta1 leads to 6(GlcNAcbeta1 leads to 3) Gal structure, and the terminal Gal of the 1 leads to 6-linked oligosaccharide was fucosylated, whereas that of the 1 leads to 3-linked oligosaccharide was sialosylated as seen below.

Carbohydrates↗
PubMed1975

Phase II study of procarbazine, CCNU, and vincristine combination chemotherapy in the treatment of malignant brain tumors.

Forty-eight patients with primary or metastatic malignant tumors of the central nervous system (CNS) were treated with combination chemotherapy, consisting or procarbazine (100 mg/m2 X 14 days), CCNU (75 mg/m2), and vincristine (1.4 mg/m2 X 2, 1 week apart) (PCV) every 4 weeks. Most patients had undergone initial resection of primary tumors, postoperative radiotherapy, and a post irradiation interval of 3 months or more. Other patients harbored unbiopsied, newly-discovered primary or metastatic tumors. All patients were deteriorating neurologically when treatment began. Overall response rate for PCV combination therapy was 44%, no better than results obtained with single agent procarbazine or BCNU, the most effective drugs used alone in previous brain tumor chemotherapy studies.

Brain Neoplasms↗