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Biomedical subjects

L L Wood

Publications and source records attributed to L L Wood.

17 recordsLinked to original sources
PubMed2001

Do response time limitations counteract the effect of faking on personality inventory validity?

Different models of lying on personality scales make discrepant predictions on the association between faking and item response time. The current research investigated response time restriction as a method for reducing the influence of faking on personality scale validity. In 3 assessment simulations involving 540 university undergraduates responding to 2 common, psychometrically strong personality inventories, no evidence emerged to indicate that limiting respondents' answering time can attenuate the effects of faking on validity. Results were interpreted as failing to support a simple model of personality test item response dissimulation that predicts that lying takes time. Findings were consistent with models implying that lying involves primitive cognitive processing or that lying may be associated with complex processing that includes both primitive responding and cognitive overrides.

Adult↗
PubMed1999

Are health states "timeless"? The case of the standard gamble method.

The standard gamble method, as currently recommended for use in health care program evaluation, provides an individual's preference score or "utility weight" for living in a given health state for the rest of the individual's life. Many researchers interpret this value as a time-independent or "timeless" one and order health states on a scale of zero (death) to one (full health), regardless of the time spent in the health state. This article examines whether preference scores for a severe pain health state are "timeless," or in other words whether the utility independence assumption is satisfied. Our study results suggest that for the majority of respondents, the preference scores are not independent of time.

Aged↗
PubMed1999

Willingness to pay as a measure of health benefits.

In this paper, we discuss the use of cost-benefit analysis (CBA) for evaluating new healthcare interventions, present the theoretical basis for the use of willingness to pay as a method for valuing benefits in a CBA and describe how to obtain willingness-to-pay (WTP) measures of health benefits and how to use these values in a CBA. We review selected economic studies on consumer demand and consumer surplus and studies presenting WTP estimates for healthcare interventions. The theoretical foundations of willingness to pay as a measure of commodity value are rooted in consumer demand theory. The area under the fixed income consumer demand curve represents the consumer's maximum willingness to pay for the commodity. We identify 3 types of potential benefits from a new healthcare intervention, namely patient benefits, option value and altruistic value, and suggest WTP questions for valuing different combinations of these benefits. We demonstrate how responses to these questions can be adjusted for income effects and incorporated into economic evaluations. We suggest that the lack of popularity of CBAs in the health area is related to the perceived difficulty in valuing health benefits as well as concern over how CBA incorporates the distribution of income. We show that health benefits can be valued using simple survey techniques and that these values can be adjusted to any desired income distribution.

Consumer Behavior↗
PubMed1998

Valuing outcomes in health care: a comparison of willingness to pay and quality-adjusted life-years.

Quality-adjusted life-years (QALYs) and willingness to pay (WTP) are two preference-based measures of health-related outcomes. In this article, we compare these two measures in eliciting individuals' preferences for health outcomes associated with shingles. To collect the necessary preference data, we administered computer-interactive interviews to a sample of 65- to 70-year-olds. We found no significant correlation between QALYs and WTP across individuals. We discuss our findings and argue that our results raise questions about whether QALYs and WTP are equivalent preference-based measures of health outcomes.

Aged↗
PubMed1996

Estimating the cost effectiveness of atovaquone versus intravenous pentamidine in the treatment of mild-to-moderate Pneumocystis carinii pneumonia.

Pneumocystis carinii pneumonia (PCP) is the most common severe opportunistic infection, and one of the most costly, among people with AIDS. Over 50% of patients experience toxic effects of the major anti-PCP medications- cotrimoxazole (trimethoprim-sulfamethoxazole) and pentamidine. Recently, the US Food and Drug Administration approved a new oral drug therapy, atovaquone, as an alternative to pentamidine for the treatment of people with mild-to-moderate PCP who are intolerant of cotrimoxazole. We developed a decision tree model to estimate the costs and cost effectiveness of atovaquone therapy compared with intravenous pentamidine therapy for cotrimoxazole-intolerant patients with mild-to-moderate PCP. Clinical outcomes were based on data from a phase III trial comparing the 2 medications. Our economic outcomes were based on treatment algorithms derived from discharge data, published reports and the clinical judgement of the co-authors. We estimate the total expected cost of treating a patient for an episode of PCP with atovaquone to be $US3990 compared with $US6545 for pentamidine under our baseline scenario (1995 dollars). Our decision model also provides insight into the large cost-savings benefits of treating mild-to-moderate PCP on an outpatient basis.

Antifungal Agents↗
PubMed1991

A collaborative study to establish a U.S. reference for tissue plasminogen activator (t-PA).

In 1987 the Second International Standard for tissue plasminogen activator (t-PA) was established by the World Health Organization following an international collaborative study. At that time, the Center for Biologics Evaluation and Research (CBER) decided to establish a national reference t-PA to be used in lot release potency testing of Alteplase, a licensed t-PA biological or of other t-PAs in development. A candidate recombinant t-PA (rt-PA) preparation was donated by Genentech, Inc. (South San Francisco, California) for this purpose and a collaborative study was launched to calibrate this material against the 2nd I.S. Four laboratories (including the Center for Biologics Evaluation and Research (CBER) and three manufacturers) participated in the study to establish the potency of the rt-PA preparation using a clot lysis assay. The results indicate that the potency of the U.S. reference for t-PA is 2900 international units (IU) per vial.

Humans↗
PubMed1990

Characterization of tissue plasminogen activator binding proteins isolated from endothelial cells and other cell types.

Human tissue plasminogen activator (t-PA) was shown to bind specifically to human osteosarcoma cells (HOS), and human epidermoid carcinoma cells (A-431 cells). Crosslinking studies with DTSSP demonstrated high molecular weight complexes (130,000) between 125I-t-PA and cell membrane protein on human umbilical vein endothelial cells (HUVEC), HOS, and A-431 cells. A 48-65,000 molecular weight complex was demonstrated after crosslinking t-PA peptide (res. 7-20) to cells. Ligand blotting of cell lysates which had been passed over a t-PA affinity column revealed binding of t-PA to 54,000 and 95,000 molecular weight proteins. Several t-PA binding proteins were identified in immunopurified cell lysates, including tubulin beta chain, plasminogen activator inhibitor type 1 and single chain urokinase.

Carrier Proteins↗
PubMed1990

Immobilization of enzymes with polyaziridines.

A novel method of enzyme immobilization using a low molecular weight prepolymer of tri-functional aziridines which can immobilize enzymes both by covalent attachment and entrapment within a gel matrix is described. The enzymes are immobilized on a solid support and exhibit an excellent retention of enzymatic activity. The immobilization procedure is essentially a single step process which can be easily performed at room temperature or 4 degrees C in either aqueous solution or in an inert organic solvent. The polyaziridines used in the immobilization are nontoxic, available in bulk at low cost and completely miscible with water and many organic solvents, thus providing one of the most satisfactory methods of immobilization available.

Biotechnology↗
PubMed1984

Lipids, lipoproteins, and endocrine profiles during pregnancy in the African green monkey (Cercopithecus aethiops).

In an attempt to establish relationships between the endocrine and lipid metabolism during pregnancy, the changes in total plasma cholesterol (TPC) and lipoprotein cholesterol that occur during pregnancy in the African green monkey were investigated longitudinally in ten females in relation to the changes in progesterone, estradiol, and fasting insulin concentrations. Respective means for TPC, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) plus very low-density lipoprotein (VLDL) cholesterol were 343 +/- 35, 108 +/- 9, and 235 +/- 36 mg/dL prior to the estimated date of conception in ten females fed a high-fat, high-cholesterol diet. The concentration of these lipids fell to 225 +/- 31, 54 +/- 4, and 168 +/- 29 mg/dL for TPC (P less than 0.001), HDL cholesterol (P less than 0.001), and LDL + VLDL cholesterol (P less than 0.001), respectively, by midpregnancy (84 days). Progesterone concentrations increased during the first 60 days of pregnancy and were negatively correlated with HDL cholesterol concentrations (r = -0.57, P less than 0.02). After reaching their highest mean value, progesterone concentrations then plateaued at lower concentrations until parturition. The decrease in progesterone concentrations was associated with an initial rise in estradiol concentrations, which reached their highest concentrations in late pregnancy and were inversely correlated with HDL-cholesterol concentrations (r = -.32, P less than 0.01). Although glucose concentrations remained steady during gestation, insulin concentrations were elevated compared to postpartum concentrations (P less than 0.05) suggesting that insulin resistance occurred during the pregnancy in this nonhuman primate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Time course of diet-exacerbated carotid artery atherogenesis in the White Carneau pigeon.

The carotid arteries of White Carneau pigeons fed an atherogenic diet developed fatty streaks, proliferative and atheromatous lesions. The carotid bifurcation had accelerated lesion development when compared to either the proximal internal carotid or the dorsal carotid artery. After 4 weeks of being fed an atherogenic diet, the bifurcation region of all birds showed some lesion involvement. Lesions at the bifurcation initially involved the medial and lateral walls; flow dividers became involved slightly later, with the anterior flow divider consistently developing thicker lesions than the posterior flow divider. Lesions progressed in terms of length of circumference, mean thickness, cross-sectional area, and percent lumen stenosis as the time fed the atherogenic diet increased.20

Animals↗
PubMed1978

A rapidly polymerizing polyurethane for transcatheter embolization.

A polyurethane prepolymer was evaluated as a transcatheter embolizing agent. Low viscosity permits injection through small catheters. Polymerization is initated on contact with blood and completed within 10 seconds. Downstream propagation is better then that of cyanoacrylate and comparable to that of silicone rubber. No systemic toxicity was observed in acute animal experiments. However, dissolution of arterial walls and extravasation out of the vascular bed of chronically embolized organs suggest significant local tissue toxicity and make further evaluation necessary before clinical testing.

Abscess↗
PubMed1978

Bacterial endocarditis with obstruction of the right atrioventricular orifice and the pulmonary outflow trace in an African monkey (Cercopithecus aethiops).

A 7 to 8-year-old male African green monkey (Cercopithecus aethiops) was found moribund in his cage. Fluid and antibiotic therapy were administered, but the monkey dies 2 hours later. At necropsy, large septic mural thrombi obstructed the right atrioventricular orifice and the pulmonary outflow tract, and smaller septic thrombi were attached to the leaflets of the pulmonary and mitral valves. Staphylococci were isolated from the large thrombus occluding the atrioventricular orifice. Large abscesses were present in the upper and lower lobes of the right lung, and small, wedge shaped infarcts were present in the lungs and kidneys. The clinical and pathologic findings were consistent with a rapidly progressive form of bacterial endocarditis. This was the only case of vegetative bacterial endocarditis seen at this instituion in 700 necropsies of nonhuman primates.

Animals↗
PubMed1977

Stimulation of cholesterol esterification in rhesus monkey arterial smooth muscle cells.

The influence of homologous high density lipoprotein (HDL) and low density lipoprotein (LDL) and of whole hypercholesterolemic serum on the esterification of oleic acid and cholesterol was studied in rhesus monkey arterial smooth muscle cells. Whole hypercholesterolemic serum and isolated LDL stimulated cholesterol esterification as much as 10-fold using either cholesterol-1,2-3H or oleate-1-14C as substrate. At the same concentrations of cholesterol, HDL stimulated cholesterol esterification to a lesser extent, to a maximum of 3-fold. Associated with the stimulation of cholesterol esterification by LDL or whole hypercholesterolemic serum was a greater than 10-fold increase in the cholesteryl ester content of the arterial smooth muscle cells. Esterification to cholesterol reached a maximum after 8-12 hours of culture with either hypercholesterolemic serum or LDL. The stimulation of esterification was specific for esterification to cholesterol because there was little change in incorporation of fatty acid into triglycerides and phospholipids. These studies provide further evidence that a major consequence of the interaction of plasma LDL with the cellular elements of the arterial wall is a stimulation of cholesterol esterification. These studies, coupled with the observation that cholesteryl esters, more than any other single component, increase in the atherosclerotic artery, suggest an important role of a stimulation in cholesterol esterification in the pathogenesis of atherosclerosis.

Animals↗