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Biomedical subjects

G G Liu

Publications and source records attributed to G G Liu.

14 recordsLinked to original sources

Economic costs of HIV infection: an employer's perspective.

The introduction of highly active antiretroviral therapy has proven highly effective in treating patients with HIV/AIDS. However, the high cost of the advanced antiretroviral therapy has led to increased financial constraints on both patients and payers. From business firms'perspective, especially those with operations in developing countries, it is crucial to determine the long-term economic cost implications of alternative employment and benefit policies for HIV-infected workers or those at high risk for the disease. A simulation model is developed to predict the comprehensive lifetime economic costs of HIV-infected workers to an employer. This model employs age,CD4(+) cell counts,and plasma HIV-1 RNA level as major predictors of the disease progression and patient survival in the determination of various cost functions. Major cost components considered include direct expenses on health insurance premium,life insurance premium, short-term disability benefits, long-term disability benefits, hiring/training expenses, and indirect costs resulting from reduced or lost productivity at work. An individual model and a group model are derived to estimate the costs of an individual and a group of HIV-infected patients, respectively. Over a 10-year period, following the nonadvanced antiretroviral treatment regimen, the group model predicts that the total lifetime cost of an HIV-infected worker can be as high as U.S. 90,000 dollars to his/her employer, of which 60,000 dollars would be various explicit costs and 30,000 dollars lost work productivity. Sensitivity analysis further demonstrated that changes in the initial level of age,CD4(+) cell count, HIV-1 RNA viral load,CD4(+) cell decline rate, and the costs of medical care influence the dynamics of the cost functions. HIV infection can result in sizable economic costs to an employer over the lifetime course of an infected employee if not treated with the advanced antiretroviral therapy. These cost estimates provide a rational economic basis for an employer to optimally assess the longrun costs and benefits of alternative employment and insurance policies in the care of employees with HIV infection.

Journal Article↗

Acid-induced polymerization of the group 5 mite allergen from Dermatophagoides pteronyssinus.

House dust mites are the most important source of indoor allergens and cause allergic diseases. Our studies here suggest that the group 5 allergen from Dermatophagoides pteronyssinus (Der p 5) is monomeric at neutral pH, but forms filaments at low pH. Circular dichroism measurements show Der p 5 is a helical protein, and the protein sequence reveals Der p 5 contains coiled-coil helices. The acid-induced filament assembly could be explained in part by the high content of charged residues (40%) in the coiled-coil structure. Interestingly, some of the known Dermatophagoides allergens also contain a heptad repeat, which could potentially form coiled coils. Therefore, coiled-coil helices may be one of the common structural motifs of mite allergens that contribute to their allergenicity.

Allergens↗

DIAN: a novel algorithm for genome ontological classification.

Faced with the determination of many completely sequenced genomes, computational biology is now faced with the challenge of interpreting the significance of these data sets. A multiplicity of data-related problems impedes this goal: Biological annotations associated with raw data are often not normalized, and the data themselves are often poorly interrelated and their interpretation unclear. All of these problems make interpretation of genomic databases increasingly difficult. With the current explosion of sequences now available from the human genome as well as from model organisms, the importance of sorting this vast amount of conceptually unstructured source data into a limited universe of genes, proteins, functions, structures, and pathways has become a bottleneck for the field. To address this problem, we have developed a method of interrelating data sources by applying a novel method of associating biological objects to ontologies. We have developed an intelligent knowledge-based algorithm, to support biological knowledge mapping, and, in particular, to facilitate the interpretation of genomic data. In this respect, the method makes it possible to inventory genomes by collapsing multiple types of annotations and normalizing them to various ontologies. By relying on a conceptual view of the genome, researchers can now easily navigate the human genome in a biologically intuitive, scientifically accurate manner.

Algorithms↗

Role of barium nitrate on the sulfur fixation of calcium oxide.

In this paper, the effect of Ba(NO3)2 on the efficiency of sulfur fixation of calcium oxide during coal combustion was studied. The results showed that addition of barium nitrate to the CaO can enhance the sulfur removal rate of CaO significantly. The X-ray diffraction spectrum of residual ash of coal added some sulfur fixative expressed that Ba2+ can form a compound of Ba-Al-Si-O which encloses the CaSO4 to prevent it's decomposition, so Ba2+ can improve the action of sulfur fixation of CaO. The combustion character of the original coal and original coal added sulfur fixative was researched with thermal-gravity analyzer and the results expressed that adding some sulfur fixative to the coal will make the combustion character of coal change little.

Air Pollutants↗

An economic cost analysis of oral ganciclovir prophylaxis for the prevention of CMV disease.

PURPOSE: The study conducted an economic cost analysis of oral ganciclovir prophylaxis in preventing cytomegalovirus (CMV) disease for AIDS patients in a randomized clinical trial setting. METHODS: Data were generated from patient interviews, medical records, and case reports from a multi-center, randomized, double-blind, and placebo-controlled pharmacoeconomic study appended to a clinical trial. The outcomes were measured in monthly cost per patient. Various cost functions were tested in the context of sample-selection model (SSM) and two-part model (TPM), and were estimated using both the ordinary least squares (OLS) and the bounded influence estimation (BIE) methods. RESULTS: The use of informal caregiver services did not differ significantly between patients in the treatment group and those in the placebo group. The OLS estimates for the ganciclovir prophylaxis arm showed a reduced, but statistically insignificant use of formal care in both outpatient and inpatient settings. The BIE results for the ganciclovir prophylaxis arm, in contrast, showed a significant reduction of 27% in hospital cost among hospital users, and 44% among the total sample of AIDS patients. The monthly total cost function also identified a decreasing but insignificant trend due to the treatment effect. CONCLUSIONS: At the methodological level, this study demonstrated the value of employing more rigorous econometric techniques in identifying subtle treatment effects on cost outcomes from clinical trial data in the economic assessment of medical technologies. At the empirical level, the study concluded that beyond its demonstrated efficacy of preventing CVM disease among AIDS patients, ganciclovir prophylaxis did not lead to additional health care costs, other than the cost of the drug therapy.

Acquired Immunodeficiency Syndrome↗

An economic analysis of antimicrobial prophylaxis against urinary tract infection in patients undergoing transurethral resection of the prostate.

Despite the high level of safety and low incidence of mortality associated with transurethral resection of the prostate (TURP), urinary tract infections (UTIs)-the most common complication associated with this procedure-continue to be an important source of postoperative morbidity and costs. However, there is controversy about whether antimicrobial agents should be used as UTI prophylaxis in patients undergoing TURP and, if so, which agents should be used and for what duration. This retrospective study used multivariate regression analysis to evaluate the different types and durations of antibiotic prophylaxis in 222 patients who underwent TURP at a Veterans Affairs hospital between January 1, 1995, and March 30, 1998. The primary outcome measures were total medical costs (ie, medication use, clinic office visits, and hospital care in the 4 weeks after the procedure), length of hospital stay (total days in hospital due to the procedure), and probability of UTI (incidence of infection in the 4 weeks after the procedure). Results showed that there was no difference in the length of hospital stay regardless of the regimen or duration of pre-TURP antibiotic therapy. Patients who received pre-TURP ampicillin plus ceftizoxime incurred moderately higher total medical costs than did patients who received the least costly drug, cefazolin (P = 0.10). Similarly, patients who received post-TURP quinolones incurred a significantly higher total medical cost than did patients who received co-trimoxazole (P = 0.06). We found no evidence of a relationship between use of specific parenteral or oral antibiotic prophylaxis for UTI in patients undergoing TURP and the rate of UTI in such patients. Thus there is no justification for the use of more expensive antibiotic regimens. At our institution, the preferred pre-TURP prophylactic regimen would be cefazolin, whereas co-trimoxazole would be the most cost-effective post-TURP prophylactic regimen. Because duration of post-TURP prophylaxis does not appear to influence the rate of UTI, 24 hours would seem adequate.

Anti-Bacterial Agents↗

Birth outcomes and the effectiveness of prenatal care.

OBJECTIVE: To investigate pregnant women's self-selection effects on the estimation of birthweight production function. A particular emphasis is placed on assessing the effectiveness of prenatal care as a major medical input in the birthweight production function. DATA SOURCES: Primary data compiled from birth and abortion certificates for the Commonwealth of Virginia in 1984. Several area-specific socioeconomic variables were also employed from the Area Resource File 1984; Supplemental Food Program for Women, Infants, and Children (WIC) Local Agency Directory; and the family planning clinics data by the Alan Guttmacher Institute (AGI). STUDY DESIGN: Two types of self-selection effects are defined: selection effect due to sample censoring from the resolution of pregnancies as live births or induced abortions; and selection effect due to the use of prenatal care as an endogenous variable. Race- and location-specific birthweight production functions are estimated using models with and without correction for self-selection effects. PRINCIPAL FINDINGS: The self-selection effect in the resolution of pregnancies is race-specific, being significant for African American women. The effectiveness of prenatal care in birthweight production is underestimated substantially by the selection bias from the use of prenatal care, and overestimated by the selection bias from pregnancy resolutions. On average, the overall estimated effectiveness of prenatal care is over five times higher after controlling for the selection effects. CONCLUSIONS: Self-selection effects could be a very serious problem in measuring the effectiveness of birthweight determinants in general. The overall effectiveness of prenatal care, in particular, tends to be significantly biased downward without controlling for selection effects. The significance and scale of the bias depends crucially on specific data and cohorts of the population investigated.

Abortion, Induced↗

An economic analysis of Chinese fertility behavior.

This paper is the first to present a Chinese general fertility model that simultaneously controls for the endogeneity of infant mortality and per capita income determination at county level. Using the 1982 Chinese population census data, comprising 2305 observational units, this analysis improves on existing studies in several ways. First, since all the underlying variables are measured at the Chinese county level, we treat both the per capita income and infant mortality rates as endogenous, as opposed to exogenous as assumed in most previous studies on Chinese fertility. Our testing results strongly reject the null hypothesis of the exogeneity of both infant mortality and income determination within our model. Secondly, concerning the hypothesis of nonlinear income effect on fertility behavior, we examine both the variable income-elasticity and constant income-elasticity models. Strong evidence is obtained in support of the variable income elasticity model, predicting a U-shaped income effect on Chinese general fertility. This suggests that a more equitable income distribution leads to a reduction in the Chinese fertility rates. Thirdly, employing the two stage least squares procedure, we find a much stronger positive replacement effect on infant mortality when the endogeneity of infant mortality and income are both controlled for simultaneously. Our results indicate that Chinese general fertility may well be shaped by optimizing behavior.

Adolescent↗

An economic analysis of pregnancy resolution in Virginia: specific as to race and residence.

This study analyses an economic model of pregnancy resolution; that is, a model of the choice by a pregnant woman to abort her fetus or carry it to term. This analysis, using an analytical model derived from the household utility framework, adds to previous research by presenting race- and residence-specific estimates of how individual characteristics, history of abortion, and the community-based factors determine women's choices of giving birth vs. aborting. The main data for estimating the model were drawn from the 1984 vital statistics of all induced abortions and live births in the Commonwealth of Virginia. The major findings indicate that low parental education, high maternal age, previous early abortions, and the availability of abortion providers all significantly reduce the probability of choosing the live birth option. Married status and the availability of family planning clinics significantly increase the probability of the live birth option. The findings also suggest that women's choices between abortion and live birth vary substantially with race (White vs. Black) and residential (urban vs. rural) location.

Abortion, Induced↗

[Traumatic rupture of trachea and major bronchus].

The rupture of the tracheobronchial tree in closed trauma is a severe. Early diagnosis of the disease is usually overlooked. 6 cases were reported in this article. The pathogenesis, X-ray features and early diagnosis of the disease were discussed. The main causes of the mis-diagnosis were analysed.

Adult↗

The effects of theophylline and caffeine on thermoregulatory functions of rats at different ambient temperatures.

Both systemic and central administration of theophylline and caffeine produced a dose-dependent rise in rectal temperature at ambient temperatures of 8, 22 and 30 degrees C. The hyperthermia in response to either xanthine was brought about by an increase in metabolic heat production. In addition, their administration produced behavioral excitation, cutaneous vasodilation (as estimated by an increase in the foot and tail skin temperatures) and diuresis. There was no change in respiratory evaporative heat loss. Probably, the hyperthermia induced by the two drugs was due to behavioral excitation leading to an increased metabolism at the ambient temperatures studied. Furthermore, either destruction of central catecholaminergic nerve fibres (with 6-hydroxydopamine) or blockade of alpha-adrenergic and dopaminergic (with phentolamine and haloperidol) receptors antagonized the xanthine-induced hyperthermia. The data suggest that these xanthines elicit a central activation of both adrenergic and dopaminergic receptors via release of endogenous catecholamines that leads to behavioral excitation and hyperthermia in rats.

Animals↗

Effects of Chinese herb, Huang Chin (Scutellaria baicalensis George) on thermoregulation in rats.

Intragastric administration of a Chinese herb, Huang Chin extract (Scutellaria baicalensis George), produced a dose-dependent fall in rectal temperature in conscious rats in a room the temperature of which was 22 degrees C or below. The hypothermia in response to Huang Chin application was brought about solely by cutaneous vasodilatation (as estimated by an increase in cutaneous temperatures). There were no changes in either metabolic heat production or respiratory evaporative heat loss. However, in the heat (29 degrees C), Huang Chin administration produced no changes in rectal temperature or other thermoregulatory responses. The data indicate that Huang Chin extract produces peripheral vasodilatation which leads to a hypothermia in conscious rats.

Animals↗

Effects of stimulation of acupuncture loci Ta-Chuei (Go-14), Nei-Kuan (EH-6) and Tsu-San-Li (St-36) on thermoregulatory function of normal adults.

The effects of acupuncture stimulation on the Ta-Chuei (Go-14), Nei-Kuan (EH-6), and Tsu-San-Li (St-36) loci on thermoregulatory function were assessed in normal adults. Stimulation of acupuncture locus Ta-Chuei produced hypothermia. The hypothermia was brought about by a decrease in metabolic rate, an increase in cutaneous circulation (the back region) and perspiration. On the other hand, acupuncture stimulation of either the Nei-Kuan or Tsu-San-Li loci produced a slight hyperthermia. The hyperthermia was due to a decrease in cutaneous circulation. The data indicate that each acupuncture locus may have its own function with special reference to body temperature regulation.

Acupuncture Therapy↗