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Biomedical subjects

D McFarland

Publications and source records attributed to D McFarland.

At least 19 recordsLinked to original sources
PubMed1997

Possibly optimal decision-making under self-sufficiency and autonomy

Any self sufficient autonomous agent faces multiple tasks to which it must sequence its behaviour if it is to manage its time appropriately. This paper considers the minimal multiple task scenario - the two resouce problem. Some possible mechanisms, inspired from ideas in ethology and having claim to perform optimally when analysed mathematically, are considered: one based on cost function and another based on motivational tendancies. Several variants of the mechanisms are implemented and tested in a continuous two dimensional simulation environment under a variety of conditions. Those mechanisms closely linked to cost functions do not perform well, are not adaptive, and dither. The mechansisms based on motivational tendancies perform better, are more adaptive, and demonstrate opportunism. The difficulty of finding effective mechanisms by using a functional perspective is noted.Copyright 1997 Academic Press Limited Copyright 1997 Academic Press Limited

Journal Article↗
PubMed1996

The quest for TQM in a community mental health center: using the Baldrige criteria as a framework.

BACKGROUND: The St Louis Mental Health Center, an agency of the Missouri Department of Mental Health, is using the Malcolm Baldrige National Quality Award criteria as the organizing scheme for its total quality management (TQM) program. PRE-BALDRIGE STEPS: Personal readiness training for managers coincided with a strategic planning process that also focused on quality. An organizational quality structure was developed and quality improvement teams launched. SELF-ASSESSMENT: In 1994, once the management team decided to use the Baldrige criteria, it began developing and implementing organizational self-assessment criteria. However, it was not until August 1995 that the organizational self-assessment was conducted. KEY AREAS TARGETED FOR IMPROVEMENT: Critical areas for improvement were selected on the basis of their alignment with the strategic objectives, their cross-functional nature, an analysis of the costs and benefits of implementation, and the probability of and ability to measure the success of the improvement. EXAMPLE--COMPLAINT AND FEEDBACK SYSTEM: After Baldrige criteria led the agency to determine whether a complaint management process resolves issues effectively and promptly, it was apparent that complaint resolution was not monitored, and various process improvement strategies were implemented. SUMMARY AND CONCLUSION: Use of the Baldrige criteria has helped the agency move forward in its TQM program. Areas for improvement, as documented in the self-assessment phase, become part of the strategic plan. The criteria's focus on process and customer satisfaction are reassuring to staff in a changing health care environment.

Community Mental Health Centers↗
PubMed1995

Subarachnoid hemorrhage: an unusual presentation of shock.

A 42-year-old woman became profoundly hypotensive shortly after arriving at our emergency medical center after a seizure. The patient's blood pressure did not respond to aggressive fluid resuscitation, administration of inotropic agents, vasopressors, or corticosteroids. After a thorough search for the cause of shock, she was found to have a subarachnoid hemorrhage (SAH). Hypotension is a rare occurrence in SAH. Several mechanisms of SAH are reviewed in this report and are invoked to explain this patient's lack of response to the standard therapies for hypotension. Emergency physicians should consider SAH in the differential diagnosis of refractory shock in patients who present with neurologic abnormalities.

Adult↗
PubMed1995

Proximity penetrating extremity trauma: the role of duplex ultrasound in the detection of occult venous injuries.

The diagnosis and management of occult vascular injuries caused by penetrating proximity extremity trauma (PPET) remains controversial. Over 18 months, we prospectively screened 37 patients (43 lower extremities) with PPET for occult arterial and venous injuries using noninvasive studies (physical examination, ankle-brachial indices, color-flow duplex ultrasonography (CFD)) and angiography (arteriography, venography). Eight isolated, occult venous injuries were detected (incidence, 22%). CFD detected seven of eight (88%) venous injuries. Venography was technically difficult to perform in this patient population and failed to detect four femoral-popliteal vein injuries. Major thromboembolic complications (pulmonary embolism, symptomatic deep vein thrombosis, venous claudication) occurred in 50% of the patients identified with femoral-popliteal vein injuries. Arterial injuries were detected in 4 of 42 (10%) extremities (arteriography, n = 3; CFD, n = 1) and were clinically benign. We conclude that following PPET, (1) isolated, occult venous injuries are common and are associated with significant complications and (2) CFD is useful for screening for occult venous injuries.

Adolescent↗
PubMed1995

Preventive chemotherapy for HIV-associated tuberculosis in Uganda: an operational assessment at a voluntary counselling and testing centre.

OBJECTIVE: To assess the operational aspects of isoniazid preventive chemotherapy (IPT) for tuberculosis in persons dually infected with HIV and Mycobacterium tuberculosis identified at an independent HIV voluntary counselling and testing centre in Kampala, Uganda. DESIGN: HIV-infected persons were counselled, had active tuberculosis excluded by medical examination, and were offered purified protein derivative (PPD) skin testing. PPD-positive persons were offered isoniazid 300 mg daily for 6 months. Drugs were supplied, and toxicity and compliance were assessed monthly. Utilization of service, cost, and sustainability were also assessed. RESULTS: Between 14 June 1991 and 30 September 1992, 9862 persons tested HIV-positive. Of 5594 HIV-infected clients who returned to collect test results, only 1524 (27%) were enrolled. Of those, 1344 were tuberculin-tested (88%); 180 were not tested because of active tuberculosis, serious illnesses, refusal, and other reasons. Of the 1344, 250 (19%) did not return for test reading and 515 were negative (47% of tests read). Of 579 tuberculin-positive persons, 59 (10%) were excluded from preventive chemotherapy because of tuberculosis and other respiratory illnesses. Of 520 persons given isoniazid, 62% collected at least 80% of their drug supplies. No major toxicity was observed. One case of tuberculosis occurred in the first month of treatment. Cost of HIV counselling and testing was US $18.54 per person and cost of follow-up counselling and social support was US $7.89. CONCLUSIONS: Important factors were identified which caused attrition, such as limited motivation by counsellors to discuss tuberculosis issues during HIV pre- and post-test counselling, insufficient availability of medical screening, shifting of sites to collect pills, and frequent tuberculin-negative tests. Active tuberculosis among 6% of persons screened suggests that voluntary counselling and testing sites may be important for tuberculosis case finding and underscores the need to exclude tuberculosis carefully before starting IPT. In developing countries, further studies assessing the feasibility of IPT within tuberculosis and HIV/AIDS programme conditions are needed. Cost-effectiveness of IPT, compared with passive case finding, and its sustainability should be assessed before national policies are established.

AIDS-Related Opportunistic Infections↗
PubMed1994

Extended evaluation of the titanium Greenfield vena caval filter.

PURPOSE: The purpose of this study was to evaluate the long-term safety and efficacy of the titanium Greenfield filter-modified hook for prevention of pulmonary embolism. METHODS: We conducted a prospective study in 173 patients from four institutions who underwent clinical examination, abdominal radiography, and duplex ultrasound examinations of the vena cava and lower extremities. If indicated by protocol or clinical presentation, computed tomography scans, pulmonary angiograms, or venacavograms were obtained. RESULTS: The most common procedural event was filter limb asymmetry (10%), which had no clinical significance. A variety of other minor procedural events occurred in another 10% of cases. Early follow-up (< 6 months) was completed in 149 patients, and long-term evaluation was completed in 113 (> 12 months). Deaths in 24 patients were from nonembolic causes in all but one. There were four suspected or confirmed recurrent pulmonary emboli, for an incidence of 3.5% (four of 113), with one death (0.9%). Four patients had inferior vena cava occlusion at early follow-up and at long-term evaluation, only one remained occluded (1%). Insertion site venous thrombosis was seen in only two patients (2%). CONCLUSION: The titanium Greenfield filter provides protection comparable to the standard stainless steel Greenfield filter after 1 year with a low incidence of recurrent pulmonary embolism (3.5%) and a high caval patency rate (99%).

Cohort Studies↗
PubMed1992

Serotonin uptake by astrocytes in situ.

Co-localization of glial fibrillary acidic protein (GFAP) and radioactivity was examined after intraventricular injection of [3H]5-HT in adult rat brains. Radioactivity localized over GFAP-positive astrocytes was seen, especially when image-enhancing techniques were applied to the data. Also slices prepared from astrogliotic hippocampi of rats pretreated with kainic acid showed a twofold increased uptake of [3H]5-HT compared to control slices. This indicates that the uptake of [3H]5-HT seen in primary astrocyte cultures also occurs for astrocytes in situ. Also, as with astrocyte cultures, only some of the GFAP(+) astrocytes in situ showed localization of radioactivity, supporting the concept of intraregional heterogeneity of astrocyte functions.

Animals↗
PubMed1992

Treatment of chloroquine-resistant malaria in African children: a cost-effectiveness analysis.

Because chloroquine (Cq)-resistant Plasmodium falciparum (CRPF) has now spread throughout most of Africa, the efficacy and practicability of other drugs such as amodiaquine (Aq), and pyrimethamine-sulfadoxine (PS), for the treatment of fever needs to be assessed. We used a decision-analysis model to compare the cost and effectiveness of Cq, Aq, and PS. The variables considered were the probability of P. falciparum infection, drug compliance, minor and lethal side effects of the drug, the level of drug resistance in the community, and case-fatality rates associated with treatment. The measures of effectiveness were the number of malaria-related fever episodes cured parasitologically with each treatment and the number of malaria deaths prevented in children 6-59 months old. Cost-effectiveness comparisons were made for cases cured and deaths prevented. For treating 100,000 febrile episodes, Cq, PS, and Aq cost US$1812, US$2622, and US$3044, respectively. Cost of the drug, compliance, and the level of CRPF had the greatest effect on the cost-effectiveness ratio. The prevalence of high-level drug resistance (RIII) was the most important determinant of the cost-effectiveness. In a scenario with high-level CRPF, treatment with Cq costs US$0.47 to cure one patient and US$2.29 to prevent one death compared with US$0.05 and US$1.52 for treatment with PS. When the prevalence of RIII-level CRPF is greater than 14-31% (depending on the level of compliance), the most cost-effective treatment is PS, despite its 45% greater cost. Decision analysis models will be useful for malaria control planners as strategies are reconsidered in the 1990s.

Africa↗
PubMed1990

Intrahippocampal kainic acid reduces glutamine synthetase.

Kainic acid was injected into the hippocampus of rats and glutamine synthetase was measured to determine whether astrocytes are involved in the early effects of this neurotoxic agent. Glutamine synthetase was reduced by 38%, 24 h after the stereotaxic application of 4 nmol of kainic acid to this region. The reduction in glutamine synthetase by kainic acid was not due to direct inhibition of the brain enzyme. This effect also was not due to seizure activity since rats peripherally injected with a convulsant dose of kainic acid were found to have normal hippocampal glutamine-synthetase activity. Exposure of astrocyte cultures to kainic acid for 24 h produced no evidence of gliotoxicity and no change in glutamine synthetase activity. The effect of intrahippocampal kainic acid on glutamine synthetase appears to be indirect, most likely produced secondarily to its neuronal effects. Several studies have shown that endogenous glutamate is involved in kainate neurotoxicity. A reduction in glutamine synthetase by kainic acid may impair the capacity for astrocytes to metabolize glutamate. Such an impairment could contribute to the glutamate-mediated cell death following kainic acid exposure.

Animals↗
PubMed1986

Pharmacologic action of L-carnitine on hypertriglyceridemia in obese Zucker rats.

Administration of pharmacologic amounts of L-carnitine was studied in the hypertriglyceridemic Zucker rat. When administered subcutaneously, doses from 250 to 2,000 mg/kg/d significantly decreased plasma triglycerides in obese rats over eight to 12 weeks, with no effect on plasma triglycerides in lean rats. Oral doses at the same high levels were not effective in decreasing plasma triglycerides. Triglyceride secretion rate was reduced from 367 micrograms/min to 168 micrograms/min in treated obese rats. Concurrently, liver lipid was increased twofold in obese treated rats, and the livers of these rats showed significant fatty infiltration. The mechanism of action of carnitine in decreasing plasma triglycerides appeared to be via decreased secretion of triglycerides by the liver of obese rats. There was no effect of L-carnitine in lean or obese rats on the following variables: carnitine palmitoyltransferase-A kinetics or malonyl CoA inhibition, mitochondrial or peroxisomal oxidative capacity, lipoprotein lipase in heart, muscle, and adipose, or fecal lipids. The effect of pharmacologic L-carnitine thus appears to be an inhibition of triglyceride synthesis and/or secretion by the liver.

Animals↗
PubMed1980

External trabeculotomy for developmental glaucoma.

We have used external trabeculotomy in the treatment of developmental glaucoma for the past ten years. There were 57 operations involving 47 eyes in 29 individuals. The procedure was more successful in congenital than in adolescent glaucoma, and although late failure does occur with the latter, it appears to be uncommon with the former.

Adolescent↗
PubMed1980

Early behavioral abnormalities in mice due to scrapie virus encephalopathy.

The behavioral effects of scrapie virus infection, a slow degenerative disease of the central nervous system, were examined in mice. Testing was conducted at 50, 100, and 150 days postinfection and included open-field behavior, Y-maze alternation and activity, and two-way shuttle-box avoidance. The behavioral pathology was found to be task-specific rather than of a global nature. Furthermore, the effects observed could be classified as either early or late components of the disease. The relevance of this animal model to human presenile dementias is discussed.

Animals↗
PubMed1979

"Mental set" in controls, postalcoholics, chronic schizophrenics, and "organics".

Subjects consisted of (normal) controls, postalcoholics, chronic schizophrenics, and "organics" (a miscellaneous group of patients with acquired organic brain disorders including posttraumatic encephalopathy, Alzheimer's disease, Behçet's disease, Huntington's chorea and poststroke encephalopathy). "Mental set" was measured by comparisons of simple auditory-manual reaction times (RTs) at preparatory intervals (PIs) of 2, 5, and 10 sec following "warning" light flashes. First, the PIs were varied randomly over 48 trials (irregular procedure); then, each of the three PIs was held constant for 16 successive trials (regular procedure). Overall RTs increased significantly and progressively from controls to postalcoholics to chronic schizophrenics to organics. Mean differences between irregular and regular RTs at each PI were either significantly less for postalcoholics, chronic schizophrenics, as well as chronic schizophrenics and organics show distinct impairment of "mental set," which may be a sign of organic brain dysfunction, if other factors such as severe cultural deprivation can be excluded.

Adult↗
PubMed1977

Marijuana and memory impairment: effect on free recall and recognition memory.

The effect of marijuana on memory was evaluated by presenting two groups of 17 male volunteers with lists of repeated or nonrepeated words following administration of a single marijuana cigarette containing 14 mg delta9-THC. An immediate free recall, final free recall and recognition memory test followed. Results indicated that marijuana significantly decreased immediate and final free recall but only slightly influenced recognition memory. Rate of acquisition on the repeated lists was the same for both groups. Long term retention of encoded information was not influenced by marijuana. The shape of the serial position curves departed slightly from those reported by other investigators in that some effects of the drug on the recency portion of the curve were noted. Both internal and external intrusions were elevated under marijuana.

Adult↗
PubMed1977

Marijuana: dose-response effects on pulse rate, subjective estimates of potency, pleasantness, and recognition memory.

34 experienced marijuana users were divided into four equated groups of eight subjects each based on recognition memory test performance. One week later each group was retested following administration of marijuana containing 0, 5, 10 or 15 mg delta9-tetrahydrocannabinol. A dose-related effect of marijuana on pulse rate and subjective measures of potency and pleasantness occurred. Ratings of potency and changes in pulse rate were highly correlated, but this relationship did not hold within a given dosage group as determined by partial correlations. No effect of marijuana on the distribution of hit and false alarm rates or confidence ratings during the recognition memory test was noted.

Adult↗
PubMed1976

Marijuana and memory impairment: the effect of retrieval cues on free recall.

In an attempt to ascertain the effect of retrieval cues on recall deficits which occur following intoxication with marijuana, 40 male volunteers were presented with word lists following the smoking of a single one gram marijuana (0.94% delta 9 -THC) or placebo cigarette and then were required to recall these words immediately after presentation. Recall occurred under a condition in which cues representative of to-be-remembered words were present or in an uncued condition. Results indicated that recall was depressed following marijuana administration under both cued and uncued conditions with cues being only mildly effective in reversing the recall deficit. There was no increase in the number of internal intrusions under marijuana, but the number of external intrusions was significantly elevated under the cued conditions.

Adult↗