Search PubMed⌕ Search

Biomedical subjects

A Gafni

Publications and source records attributed to A Gafni.

At least 163 records · Page 9Linked to original sources
PubMed1991

Equity considerations in utility-based measures of health outcomes in economic appraisals: an adjustment algorithm.

In this paper we consider whether methods currently used to measure utility of health outcomes are consistent with the equity criteria adopted by researchers. We show that unless the chosen equity criterion is incorporated in the design of the measurement instrument, the derived health state utilities are inconsistent with the equity criterion (except under special circumstances). Adjustment algorithms are derived, based on the axioms of von Neumann-Morgenstern utility theory, which take account of difference equity criteria currently adopted in the literature. The proposed approach is based on simple lottery questions of the type already used widely in empirical studies.

Algorithms↗
PubMed1991

Exposure of rat muscle phosphoglycerate kinase to a nonenzymatic MFO system generates the old form of the enzyme.

The occurrence of age-related modifications in enzymes is a well-established symptom of aging that has been explained by several possible mechanisms including the oxidation of amino acid residues by mixed-function oxidation (MFO) systems. In the present study native old phosphoglycerate kinase was compared with young enzyme which had been modified by oxidation with ascorbate: FeCl3 followed by reduction. The comparison was done by monitoring the rates of heat denaturation of these enzyme forms, as well as their inactivation by trypsin. A remarkable similarity between the old and treated young enzyme was revealed, while native young phosphoglycerate kinase was inactivated with a different rate. Extensive unfolding followed by refolding converted both old and MFO-treated young phosphoglycerate kinase to species which greatly resemble the native young enzyme in their heat inactivation kinetics. These results demonstrate that the exposure of phosphoglycerate kinase to the mixed-function oxidation system introduces some modifications which are not reversed by subsequent enzyme reduction and which resemble those found in the native old enzyme. This mechanism, therefore, may account for the aging of phosphoglycerate kinase in vivo.

Aging↗
PubMed1991

Comparison of cervical, urethral, and urine specimens for the detection of Chlamydia trachomatis in women.

Cervical, urethral, and first void urine (FVU) specimens from 937 women were tested for Chlamydia trachomatis by culture or EIA to determine the most sensitive combination of tests and specimens. For cervical and urethral specimens the prevalence of infection by culture or confirmed EIA was 7.2% (67/937) at either site, 6.8% (64/937) at the cervix, and 4.3% (40/937) at the urethra. Of 67 specimens, 37 (55.2%) yielded a positive test from both the cervical and urethral swabs. Three (4.5%) of the 67 infections were only at the urethra and none were only in FVU. Only 37.3% (25/67) of all positive women had a positive FVU. The most sensitive combination was cervical swab culture and EIA, which detected 95.5% (64/67) of the infections, a substantial increase over culture only (76.1%) or EIA of the cervical swab (79.1%). The testing of urethral and FVU specimens apparently offers only minimal advantage over testing of cervical specimens only for chlamydia.

Adolescent↗
PubMed1991

A managerial approach to costing fixed assets in health care organizations: the role of depreciation and interest.

The economic aspect of depreciation and interest on capital are incorporated within a managerial accounting framework by treating both items as imputed charges to be debited to the users of the assets' services. The costs of these services is examined for individual assets that provide either uniform or declining service over the expected life, and for a stock of assets where the character of the individual assets is ignored. By using imputed charges, the hospital's net income is allocated to its sources.

Accounting↗
PubMed1991

Inhibition of proteinase K by phosphorylated sugars.

Proteolysis of lactate dehydrogenase, aldolase and the synthetic substrate N-succinylalanylalanylalanyl-p-nitroanilide by proteinase K is inhibited by glucose-6-phosphate and fructose-1,6-biphosphate. Analysis of the kinetic data obtained with the synthetic substrate indicates that the inhibition is a mixed-type and that more than one inhibitor molecule binds to proteinase K. Glucose and fructose are ineffective as inhibitors. In the presence of 0.2-4 mM fructose-1,6-biphosphate, aldolase becomes more susceptible to proteolysis, probably as a result of a conformational change induced by the substrate.

Amino Acid Sequence↗
PubMed1991

Measuring the adverse effects of unnecessary hypertension drug therapy: QALYs vs HYE.

Avoiding the adverse effects of unnecessary drug therapy is one of the key objectives of those who advocate the use of ambulatory blood pressure monitoring (ABP). The use of a proper outcome measure to assess the effect of drug therapy on patients' lifetime quality of life is clearly of great importance. The purpose of this paper is to alert readers that the use of quality-adjusted life-years (QALYs) gained as a measure of outcome is likely to underestimate such effects. Another outcome measure is suggested, that of healthy years equivalent (HYE), which enables respondents to reveal their true range of preferences. A study is called for which involves actual measurement of individual preferences and uses the more powerful and sensitive measure of outcome (HYE).

Antihypertensive Agents↗
PubMed1990

Universal precautions to prevent HIV transmission to health care workers: an economic analysis.

The universal precautions recommended by the US Centers for Disease Control (CDC), Atlanta, for the prevention of HIV (human immunodeficiency virus) transmission to health care workers are widely accepted, despite little documentation of their effectiveness and efficiency. We reviewed the evidence on the risk of HIV transmission to hospital workers and the effectiveness of the universal precautions. We also evaluated the costs of implementing the recommendations in a 450-bed acute care teaching hospital in Hamilton, Ont. On the basis of aggregated results from six prospective studies the risk of HIV seroconversion among hospital workers after a needlestick injury involving a patient known to have AIDS (acquired immune deficiency syndrome) is 0.36% (upper 95% confidence limit 0.67%); the risk after skin and mucous membrane exposure to blood or other body fluids of AIDS patients is 0% (upper 95% confidence limit 0.38%). We estimated that 0.038 cases of HIV seroconversion would be prevented annually in the study hospital if the CDC recommendations were followed. The incremental cost of implementing the universal precautions was estimated to be about $315,000 per year, or over $8 million per case of HIV seroconversion prevented. If all HIV-infected workers were assumed to have AIDS within 10 years of infection the of the program would be about $565,000 per life-year saved. When less conservative, more probable assumptions were applied the best estimate of the implementation cost was $128,862,000 per case of HIV seroconversion prevented. The universal precautions implemented in the study hospital were not found to be efficacious or cost-effective. To minimize the already small risk of HIV transmission in hospitals the sources of risk of percutaneous injury should be better defined and the design of percutaneous lines, needles and surgical equipment as well as techniques improved. Preventive measures recommended on the basis of demonstrated efficacy and aimed at routes of exposure that represent true risk are needed.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Resource allocation, equity and public risk: dying one at a time vs dying all together.

This paper focuses on the evaluation, from an individual and societal perspective, of risk in terms of possible loss of life due to an exposure to two different types of events over a period of time. The two types are: risk of death from a catastrophic event (a sudden death of many people in a disaster at a yet unknown point in time) expected to occur during a planning period, or risk of death from another event (e.g. disease, road accident, etc) which claims fewer lives each year, but for which the expected total number of deaths over the planning period is equal to the expected number of deaths from the catastrophic event. Our analysis considers the extreme case in which these two types of events have the same probabilities of death every year and the same expected number of fatalities over the planning period. The individual's decision problem is described using a von-Neumann Morgenstern (vNM) utility function. The model suggests that the choice between these types of events depends on the value of the following variables: the probability of death over the planning period, the length of the planning period, the individual's time preference pattern, and the utility of being in different anxiety states. Stochastic extensions that may direct the public decision making process (involving aggregated preferences) are discussed. We also discuss issues of implementation.

Catastrophic Illness↗
PubMed1990

Evaluating health related quality of life: an indifference curve interpretation for the time trade-off technique.

A commonly used method of measuring cardinal preferences for the purpose of evaluating health related quality of life is the time trade-off (TTO) technique. The TTO technique, although offered as a substitute to the standard gamble (SG) technique, is not related in a general way to any existing behavioral theory. We suggest that in the context of value function theory the TTO technique is a method which enables us to identify different points on an individual's indifference curve in his evaluation space. Creating a formal theoretical foundation for the TTO technique enables us to better understand and interpret the outcome of our measurements. We show, for example, that the current way of calculating the value preference of a given health state assumes a very specific set of specific set of value functions. This assumption has not been validated in empirical studies and thus casts doubt upon the interpretation of these values as being the value preferences of individuals for these health states.

Humans↗
PubMed1990

Individual correlates of health service utilization and the cost of poor adjustment to chronic illness.

It was conjectured that a small group of chronically ill in tertiary ambulatory clinics consume a large amount of health resources and that, from the perspective of the patient, psychosocial rather than disease variables would most explain their health service utilization and subsequent cost. New referrals with a chronic illness (N = 215) to one of three clinics (oncology, rheumatology, and gastroenterology) consented to participate in a subsequent trial of a psychosocial intervention designed to promote their adjustment to illness and, conceivably, to reduce their health service utilization. At baseline an inventory to describe the disease, treatment, functional capacity, prognosis, and socioeconomic situation of consenting subjects was completed. In addition, subjects completed the Psychosocial Adjustment to Illness Inventory (PAIS-SR), the Family Assessment Device (FAD), the Meaning of Illness Questionnaire (MIQ), and a Health Service Utilization Inventory designed to assess direct and indirect costs of health resources. These data were entered into a concurrent analytic survey design. Participating subjects represented a more socioeconomically advantaged and better-adjusted group of chronically ill patients compared with others referred to the tertiary clinics. They were representative of all new referrals in their use of the majority of health services. However, once hospitalized, participating subjects stayed longer and used specialists less. There was no important relationship between disease severity or prognosis and any type of service utilization, including hospitalization. Because the strongest correlate of all types of health services consumed was psychosocial adjustment to illness (r = 0.28 to 0.33), patients were partitioned into one of three categories of adjustment to illness: good, fair, and poor. The total annual cost per patient was $23,883, if poorly adjusted, compared with $9,791 if well adjusted. If cash transfers (benefits paid by different types of insurance) are added, the average 1987 annual cost per poorly adjusted subject was $31,291 per patient, compared with $13,771 for a patient well adjusted to the illness. There was a statistically significant and economically important linear gradient in 1987 treatment costs per category of adjustment. The possible economic implications for psychosocial intervention are highlighted.

Adaptation, Psychological↗
PubMed1990

A cost-effectiveness analysis of the routine use of isoniazid prophylaxis in patients with a positive Mantoux skin test.

The role of isoniazid prophylaxis in low-risk patients with positive Mantoux skin tests has recently been questioned. In general, recent research has focused on the risk/benefit ratio. We, therefore, decided to extend these data and apply a cost-effectiveness analysis of the routine use of isoniazid prophylaxis from a societal perspective. Costs per case prevented were calculated for a 20-, 50-, and 70-yr-old low-risk patient who had a positive Mantoux test with base, high, and low costings. Rates were also calculated based on the use of direct costs alone and direct and indirect costs combined. Costs varied from Canadian $8,586.00 in a 20-yr-old patient to $40,102.00 in a 70-yr-old patient per case prevented based on direct costs with costs ranging from $3,236.00 to $11,320.00 with both direct and indirect costs included. These costs could be considered reasonable from a societal perspective but do not address the issue of any increased life expectancy resulting from chemoprophylaxis.

Adolescent↗
PubMed1990

Enhanced proteolysis of glucose-6-phosphate dehydrogenase in the presence of palmitoyl coenzyme A.

Palmitoyl coenzyme A at concentrations below its critical micelle concentration increases the rate of proteolysis of baker's yeast glucose-6-phosphate dehydrogenase by proteinase A in the pH range 4-5. both glucose-6-phosphate and NADP protect glucose-6-phosphate dehydrogenase against proteolysis, but these protective effects are diminished in the presence of palmitoyl coenzyme A. Since palmitoyl coenzyme A is known to dissociate glucose-6-phosphate dehydrogenase into dimers, the results imply that the in vivo half life of glucose-6-phosphate dehydrogenase may be controlled by a process based on the regulation of the oligomeric structure of the enzyme by the collective actions of various molecules, including palmitoyl coenzyme A.

Aspartic Acid Endopeptidases↗
PubMed1990

Investigating the fairness of the National Resident Matching Program.

The National Resident Matching Program (NRMP) was established in the early 1950s to bring order and fairness to a previously chaotic application process for internship and residency positions. Over the years many reservations were raised about the fairness of the process, specifically, that hospital programs are doing better than students are (i.e., programs obtain preferred residents more often than students receive preferred programs). This paper presents an analysis of the results of the 1986 Match. The findings do not support the claim that the results of the Match are biased in a way that favors programs. Overall, the students' success was greater (i.e., receiving on average higher-ranked choices) than was the hospital programs' success. In fact, in 20 of 22 specialty programs, the students' degree of success was greater than or equal to the success of the programs. This finding raises the question of fairness toward programs rather than students. The authors analyze factors that affected both the hospitals' and the students' degrees of success in the 1986 Match and suggest strategies for improving the Match results.

Academic Medical Centers↗
PubMed1990

The interaction of acrylamide with glyceraldehyde-3-phosphate dehydrogenase. Structural modifications in the enzyme studied by fluorescence techniques.

The interaction of acrylamide with rabbit muscle glyceraldehyde-3-phosphate dehydrogenase (GPDH) has been investigated in Tris buffer, pH 7.5. When GPDH containing about 1 mol NAD per mol of tetramer is incubated with acrylamide (0.01-0.1 M), the tryptophan emission of GPDH, initially quenched by acrylamide, slowly increases to a value exceeding that recorded before the addition of acrylamide. This effect is not observed in apoenzyme solutions, indicating that the enhancement of fluorescence results from the dissociation of some NAD from the acrylamide treated GPDH. Acrylamide inactivates GPDH but 1 mM NAD protects the enzyme from inactivation. The addition of acrylamide to GPDH, labeled with fluorescein-5-isothiocyanate (GPDH-FITC) increases the fluorescence and decreases the polarization of fluorescein. The fluorescent sulfhydryl reagent N-iodoacetyl-N'-(5-sulfo-1-naphthyl)ethylenediamine induces similar changes in the fluorescence properties of GPDH-FITC. This reagent, however, fails to react with GPDH preincubated with acrylamide and the titration of acrylamide treated GPDH with the sulfhydryl reagent 5,5'-dithiobis(2-nitrobenzoic acid) indicates the loss of up to 7 cysteine residues per tetramer. Acrylamide also decreases the heat stability of GPDH. Altogether, the data indicate that acrylamide covalently reacts with the active site cysteine residues of GPDH and subsequently induces a conformational change in the enzyme.

Acrylamide↗