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Biomedical subjects

M Powell

Publications and source records attributed to M Powell.

207 records · Page 12Linked to original sources
PubMedDate not supplied

Performance of a refrigerated charcoal trap for xenon-133.

The impulse response function of a charcoal trap to a bolus of xenon-133 was determined as a function of the total number of hours run both at room temperature and at 25 degrees C. The peak of the response function for a new trap at room temperature reached a value of 360 MPC at 11 h. After 150 h of operation, the impulse response function was determined at -25 degrees C reaching a value of only 35 MPC at 25 h. The exhaust concentration of a trap in a busy nuclear medicine department using 150 mCi of xenon per week was measured and found to be 1600 MPC. The trap was placed in the freezer and kept there while it continued in use. Over a period of 3 weeks, the concentration of xenon in the exhaust of the trap dropped to a value of 13 MPC, or less than 1% of its value at room temperature.

Air Pollution, Radioactive↗
PubMedDate not supplied

Management of bowel dysfunction: evacuation difficulties.

Bowel dysfunction affects many people and encompasses a variety of problems. This article examines the different forms of bowel dysfunction and considers the nurse's role in caring for patients with this disorder, including manual evacuation.

Adaptation, Psychological↗
PubMedDate not supplied

A two-year clinical study of the effects of two triphasic oral contraceptives on plasma lipids.

OBJECTIVE: Oral contraceptive formulations can alter plasma lipid and lipoprotein levels; however, lower-dose triphasic tablets show only minimal metabolic effects during 6 or 12 cycles of use. Involvement of lipids in chronic cardiovascular conditions, plus long-term use of oral contraceptive tablets, prompted this first 24-cycle study of the effect of triphasic formulations on young women. METHODS: 69 women assigned randomly to an ethinyl estradiol/levonorgestrel formulation (Triphasil) or an ethinyl estradiol/norethindrone formulation (Ortho 7/7/7) and 25 control women (no hormonal contraception) had blood sampled for lipids and lipoproteins pre-trial, and at 3- or 6-cycle intervals for 24 cycles. RESULTS: At cycle 24, control women experienced no significant change from baseline in any variable except apolipoprotein B (apo B). Plasma apo B increased 42% (P < .01), reflecting the LDL apo B increase (42%, P < .01). Both combination formulations significantly increased apo B (plasma, VLDL, IDL and LDL); the increases ranged between 47% and 84%. Plasma apo A1 rose (15%, P < .001) in the Ortho 7/7/7 group only. Plasma and LDL triglycerides were increased significantly (P < .001) by the norethindrone product, 43% and 81%, respectively, and plasma and LDL cholesterol, 14% and 28%, respectively. Cholesterol decreased in all other subfractions, including HDL (11%, P < .01). HDL cholesterol decreased significantly in the Triphasil group (8%, P < .05); no other cholesterol subfractions changed significantly. All cycle-24 lipid and lipoprotein values remained well within respective normal ranges. CONCLUSION: Although 2-year exposure to the triphasic oral contraceptive formulations changed the lipid risk factors for cardiovascular disease only within normal ranges, there remains potential for long-term health effects when compounded with other risk factors.

Adolescent↗
PubMedDate not supplied

Learning curve.

Explore the source record for details and available documents.

Education, Nursing, Continuing↗
PubMedDate not supplied

Dose escalation safety and tolerance study of the competitive NMDA antagonist selfotel (CGS 19755) in neurosurgery patients.

Selfotel (CGS 19755), a competitive N-methyl-D-aspartate antagonist, is neuroprotective in experimental models of ischemic cerebral injury. We studied the safety and tolerability of a single intravenous dose (0.5 to 2.0 mg/kg) of selfotel in neurosurgery patients. Thirty-two neurosurgical patients undergoing intracranial surgery were given ascending doses of selfotel 2 to 14 h before surgery. Serum selfotel levels were measured over a period of 24 h. Cerebrospinal fluid (CSF) levels were measured 1.5 to 18 h after dosing. Frequent side effects included psychomimetic symptoms such as hallucinations, abnormal dreaming, agitation, and paranoia among 20 (66%) patients. Ataxia was seen among five (16%) and dizziness among eight (25%). Symptoms occurred 38 min to 40 h from administration and persisted 5 min to 4 days. Symptom severity worsened with increasing area under the curve measurements and doses above 1.0 mg/kg. All symptoms were reversible and easily treated with intravenous haloperidol. Modest elevations of hepatic enzymes were observed among four patients. No patient had severe adverse reactions. Maximum selfotel levels attained were 143 mumol (serum) and 4.76 mumol (CSF). Peak serum levels among six patients were within potentially neuroprotective ranges. CSF levels remained detectable up to 18 h after dosing. No obvious relationship was seen between CSF drug levels and symptoms. Selfotel in doses of 0.5 to 2.0 mg/kg can be administered safely to neurosurgical patients. Maximum serum levels attained were within the range shown to be neuroprotective in experimental studies. Side effects even at the highest levels are tolerable and reversible. Selfotel use in patients at risk for cerebral injury should be further explored.

Adolescent↗