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Biomedical subjects

M C Wang

Publications and source records attributed to M C Wang.

At least 91 records · Page 5Linked to original sources
PubMed1993

20/20 Analysis: taking a close look at the margins.

This article presents "20/20 Analysis" as an experimental, output-oriented, noncategorical alternative to traditional approaches to identification of students for special education. 20/20 Analysis identifies students showing least (below 20th percentile) and most (above 80th percentile) progress toward important objectives of education in a school. The situation of each student in low 20% and high 20% groups is then examined as a basis for broad (noncategorical) approaches to improvement of learning opportunities. Case studies of two schools are present. Policy implications are considered briefly.

Child↗
PubMed1993

Statistical models for prevalent cohort data.

In prospective cohort studies individuals are sometimes recruited according to a certain cross-sectional sampling criterion. A prevalent cohort is defined as a group of individuals who have a certain disease at enrollment into the study. Statistical models for the analysis of prevalent cohort data are considered when the onset or diagnosis time of the disease is known. The incident proportional hazards model, where the time scale is duration with disease, is compared to the prevalent proportional hazards model, where the fundamental time scale is follow-up time. In certain cases the time of enrollment may coincide with another event (such as the initiation of treatment). This situation is also considered and its limitations highlighted. To illustrate the methodological ideas discussed in the paper, the analysis of data from an observational study of zidovudine (ZVD) in patients with the acquired immunodeficiency syndrome (AIDS) is presented.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Prenatal factors associated with breastfeeding duration: recommendations for prenatal interventions.

This study of 198 urban breastfeeding women examined the psychosocial, demographic, and medical factors identified prenatally that may be associated with longer breastfeeding duration and may serve as suitable areas for prenatal breastfeeding promotion interventions. Of 11 psychosocial and demographic factors examined, 5 were important influences on breastfeeding duration: anticipated length of breastfeeding, normative beliefs, maternal confidence, social learning, and behavioral beliefs about breastfeeding. Methods of multivariate linear regression were used to identify prenatal factors that influenced anticipated length. Of the 10 factors entered into the regression model, parity, plans to return to work or school by six months postpartum, and maternal confidence were the most significant factors affecting anticipated length of breastfeeding. Our data suggest several factors amenable to intervention during the prenatal period that appear to influence breastfeeding duration. Prenatal promotion efforts could easily incorporate strategies that influence factors such as normative and behavioral beliefs and maternal confidence.

Adult↗
PubMed1992

A review of the etiology and treatment of skin ulcers with wound dressings: comparison of the effects of occlusive and nonocclusive dressings.

This article reviews the etiology and treatment of skin ulceration caused by external pressure, vascular insufficiency, and diabetes. In the case of pressure sores, compression of skin against bone may cause ischemic injury to underlying fat and muscle that precedes necrosis of dermis and epidermis. Venous and arterial insufficiency lead to leg ulcers as a result of incompetency of the valves in the veins connecting the superficial to the deep venous systems and atherosclerosis, respectively. Diabetics are susceptible to foot ulcers because of atherosclerosis and the resulting occlusive arterial disease and peripheral neuropathy. Once the underlying medical condition is solved, occlusive and nonocclusive wound dressings can be used in an attempt to promote healing. A review of the literature of animal and clinical studies suggests that both occlusive and nonocclusive wound dressings promote healing compared with air-exposed wounds. Dressings that absorb wound fluid offer some advantages over those that do not absorb large quantities of fluid in heavily exudative wounds and may require less frequent dressing changes. However, the chemistry of the material that comprises the wound dressing seems unimportant unless the material is biologically active. It is likely that the next generation of wound dressings will be composed of a moisture-retaining material coupled with material that has biological activity.

Animals↗
PubMed1992

N-estimation from retrospectively ascertained events with applications to AIDS.

It is a common sampling scheme in retrospective studies that the data set includes only individuals who satisfy a certain sampling criterion. In this paper we consider the situation when the sampling criterion is a specified event, and assume that an earlier event can be retrospectively identified given the occurrence of the specified event. A semiparametric method, which is a compromise between nonparametric and parametric methods, is employed for the estimation of the expected number of the specified events (namely, the N-estimation) occurring in arbitrarily given intervals. A number of statistical properties of the estimates are developed. Due to the limitation of semiparametric models, our estimates should be regarded as conservative estimates since in general they underestimate the actual number of the specified events. This type of limitation, however, cannot be avoided with nonparametric or semiparametric models. Applications to acquired immunodeficiency syndrome (AIDS) cases are considered. The blood transfusion AIDS cases reported to the Centers for Disease Control are analyzed in detail.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Analysis of allergenic components of Bermuda grass pollen by monoclonal antibodies.

A panel of 16 monoclonal antibodies (MoAbs) directed against Bermuda grass (Cynodon dactylon) pollen (BGP) were generated for identification and purification of the major allergenic components of the eliciting antigen (Ag). Radioimmunoprecipitation (RIP) analysis revealed that there were at least eight antigenic components with molecular weights (MW) ranging from 12 kilodalton (12 kDa) to 200 kDa. Each of these components has distinct biochemical characteristics based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF). Among them, Cyn d Bd67K and Cyn d Bd58K were basic proteins, Cyn d Bd35K consisted of at least four isomeric components with isoelectric points ranging from 6.2 to 7.2. The other antigens (Cyn d Bd68K, 48K, 38K, Cyn d Bd200K, Cyn d Bd46K, Cyn d Bd25K and Cyn d Bd12K) were all acidic proteins. The IgE binding capacity of all these antigens was determined with sera from 11 BGP-allergics by using a modified radioallergosorbent test. All but one of the antigens (Cyn d Bd200K) were found to react with human IgE from sera of BGP-allergic patients. Among those human IgE-binding molecules, Cyn d Bd35K reacted with allergic sera most frequently (10 of 11), followed by Cyn d Bd58K (8 of 11) and Cyn d Bd46K (7 of 11) respectively. Our results suggest that Cyn d Bd35K, Cyn d Bd58K, and Cyn d Bd46K are major allergens of BGP, and the MoAbs we obtained should be valuable tools for further purification of these allergens.

Allergens↗
PubMed1991

Long-term safety and efficacy of zidovudine in patients with advanced human immunodeficiency virus disease. Zidovudine Epidemiology Study Group.

An epidemiologic study was initiated in 1987 to evaluate the long-term safety and efficacy of zidovudine in patients with advanced human immunodeficiency virus disease. Data from 886 patients with the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex and CD4+ lymphocyte count less than 0.25 x 10(9)/L are reported. Eighteen-month survival was 67% for the cohort. Pretreatment factors associated with increased survival time included index diagnosis of AIDS-related complex, hematocrit of 0.35 or greater, CD4+ lymphocyte count of 0.15 x 10(9)/L or greater, high functional status, and time from diagnosis of AIDS to treatment of less than 60 days. By proportional hazards analysis, development of serious anemia was the most significant factor associated with early death. Receiving zidovudine for a high proportion of time significantly improved chances of survival even if anemia developed. Serious leukopenia occurring in 37% and serious anemia occurring in 32% of patients. Nonhematologic adverse events were uncommon and no previously unreported adverse events were seen.

Adult↗
PubMed1990

Muscarinic M2 receptors coupled to inhibition of adenylate cyclase in rat heart.

The biochemical linking event between the activation of muscarinic receptors and the inhibition of adenylate cyclase was studied with rat heart ventrical membranes. The muscarinic M2 selective antagonists were more potent than the M1 selective antagonists in the displacement of non-selective labeled 3H-QNB binding to the membranes. This was also true for the M2 selective agonists, with respect to the M1 selective agonists, in the reaction medium without Gpp(NH)p. With the same preparation, the muscarinic M2 selective agents were also more potent than the M1 selective agents in the inhibition of adenylate cyclase activity. The order of potencies of these agents in the displacement of 3H-QNB binding correlated well with their order of potencies in inhibiting adenylate cyclase activity. Gpp(NH)p reduced the binding affinities of M2 selective agonists (i.e. carbachol and oxotremorine), while it did not affect the binding affinities of non-selective agonist pilocarpine, M1 selective agonist McN-A-343 and antagonists (i.e. pirenzepine, trihexyphenidyl, AF-DX-116 and methoctramine). These results suggest that in the rat heart, the inhibition of adenylate cyclase by muscarinic agonists is through activation of the M2 subtype receptor and G-protein is likely to be involved in the coupling.

Adenylyl Cyclase Inhibitors↗
PubMed1989

Low prevalence of neurological and neuropsychological abnormalities in otherwise healthy HIV-1-infected individuals: results from the multicenter AIDS Cohort Study.

Accurate description of the prevalence of neurological impairment in healthy individuals who are infected with human immunodeficiency virus type 1 (HIV-1) has relevance for public health policy, for employment issues, and for planning future health needs. Within the Multicenter AIDS Cohort Study, we determined the cross-sectional prevalence of neurological abnormalities in 270 HIV-1 seropositive homosexual and bisexual men in Centers for Disease Control Groups II and III, using a control group of 193 HIV-1 seronegative homosexual men. Utilizing a neurological and neuropsychological screening battery, we found no differences in the prevalence of neuropsychiatric symptoms or in neuropsychological performance. One hundred nineteen subjects with abnormalities on screening tests completed additional neuropsychological testing and had neurological examinations. The majority had normal results and the frequency of neurological abnormalities and impaired neuropsychological performance was not significantly increased among HIV-1 seropositive subjects. Most of the abnormalities could be attributed to causes other than HIV-1. One subject had mild HIV-1-related dementia, yielding a prevalence of 3.7:1,000 (95% confidence interval: 0.19-23.7:1,000). Magnetic resonance imaging demonstrated sulcal prominence and focal areas of high signal intensity in white matter in 63% of HIV-1 seropositive subjects and 48% of uninfected control subjects. Abnormalities in cerebrospinal fluid were noted in 23 (85%) of 27 HIV-1-infected individuals. Our studies indicate that the prevalence of dementia and other HIV-1-related neurological disorders is very low among healthy HIV-1 seropositive homosexual men. The confounding effects of factors such as substance abuse or preexisting medical conditions must be considered in the neurological evaluation of such patients.

AIDS Dementia Complex↗
PubMed1989

Acquired immunodeficiency syndrome (AIDS)-free time after human immunodeficiency virus type 1 (HIV-1) seroconversion in homosexual men. Multicenter AIDS Cohort Study Group.

To estimate the time interval between human immunodeficiency virus type 1 (HIV-1) seroconversion and acquired immunodeficiency syndrome (AIDS) diagnosis in homosexual men, prospective incident cohorts are difficult to obtain and, if assembled, provide few events owing to the long incubation time. Although seroprevalent cohorts are numerous in size and events, the information is limited due to the unknown times since seroconversion. To combine the information provided by 1,628 seroprevalent men (304 AIDS cases) and 233 seroconverters (12 AIDS cases) being followed in a multicenter study since 1984, the postseroconversion changes in hematologic variables occurring in the incident cohort were used to develop a model that allowed for the imputation of the unknown times since seroconversion for the seroprevalent cohort. Nonparametric life table methods incorporating truncation and censoring were applied for the estimation of the probability distribution of the AIDS-free time after seroconversion. The precision of the estimates was evaluated using bootstrap methods. The analysis suggested that AIDS is unlikely (less than 0.5%) in the first year; 78% of seropositive homosexual men remain AIDS-free 60 months after seroconversion; and the AIDS incidence increases for months 12-36 and levels off at 38 per 1,000 person-semesters for months 42-60. The nonparametric estimate of the incidence rate suggests a median AIDS-free time of 11 years, which is longer than previous estimates based on parametric models.

Acquired Immunodeficiency Syndrome↗
PubMed1989

[Using anti-sera and monoclonal antibodies against Aspergillus fumigatus to study its cross-reactions with Alternaria alteria and Penicillium sp].

Using rabbit polyclonal and mouse monoclonal antibodies against Aspergillus fumigatus, we analyzed their cross-reaction with Alternaria alteria and Penicillium sp. by enzyme immuno assay (EIA) and radioimmunoprecipitation (RIP). It was found that neither of these two categories of antibodies reacted with Alternaria alteria while both reacted with Penicillium sp.. When components from Penicillium sp. precipitated by rabbit antisera were analyzed on 10% SDS-polyacrylamide gel electrophoresis (SDS-PAGE), a wide range of bands with molecular weights larger than 90 K and a single 70 K band were observed. No band was found after the rabbit antisera was adsorbed with Aspergillus fumigatus. Moreover, two monoclonal antibodies against Aspergillus fumigatus cross-reacted with high molecular weight (greater than 200K) components of Penicillium sp.. These results suggest that the antigen of Alternaria alteria is different from that of Aspergillus fumigatus, and that Penicillium sp. and Aspergillus fumigatus share some antigenic components. In another experiment, human allergic sera containing IgE antibodies to Aspergillus fumigatus were tested against Penicillium sp. by RIP. No cross-reaction was observed. This suggests that in spite of sharing common antigenic components between these two fungi, the allergenic components of Aspergillus fumigatus is different from those of Penicillium sp..

Alternaria↗
PubMed1988

Monoclonal antibodies specific for human IgE and their clinical applications.

By applying the hybridoma technique, two mouse anti-human Immunoglobulin E (IgE) monoclonal antibodies, designated as E17-58 and E20-62, were generated and characterized. E17-58 was a murine IgG2b with an affinity constant of 4 x 10(8)l/mole. E20-62 was a murine IgG1 with an affinity constant of 1 x 10(8) l/mole. These two antibodies recognized different antigenic determinants specific to the IgE molecule. They were used in combination to quantify the total serum IgE level of forty-nine persons. Data obtained correlated highly with that obtained by using the Pharmacia PRIST Kit (r = 0.91). E17-58 was also used to detect the anti-Aspergillus specific IgE of twenty-one atopic patients by a radioimmunosorbent test. The positive rate detected correlated very well with the skin test (p less than 0.05). In addition, in the Western blot system, these monoclonal antibodies were capable of identifying IgE binding components of crude allergen extracts. Extracts from pollens of Bermuda grass were evaluated, and a new major allergenic component with a molecular weight of 40 kd was identified.

Animals↗
PubMed1986

The effect of zinc deficiency and food restriction on prostaglandin E2 and thromboxane B2 in saliva and plasma of rats.

Zinc has been implicated in the regulation of prostaglandins and other arachidonic acid derivatives. Studies of zinc-deficient animals, however, are compromised by concomitant reduction in food intake that may also alter eicosanoid levels in body tissues and fluids. In this study, three groups of rats, designated as zinc-deficient, pair-fed and control, were fed diets containing 1 ppm, 15 ppm (in amounts paired to deficient rats) and 15 ppm Zn ad libitum, respectively, for 6 weeks. Saliva and blood were analyzed for PGE2 and TXB2 by radioimmunoassay. Saliva concentrations of both eicosanoids were lower (p less than 0.05) in the pair-fed animals, but not significantly altered by zinc deficiency. Plasma levels of PGE2 and TXB2 were unchanged by either zinc deficiency or food restriction. The results of this study support the contention that the effect of zinc on these prostaglandins is not mediated by altered rates of synthesis or degradation but rather by effects on eicosanoid function.

Animals↗
PubMed1986

Relative reliability of five serially measured markers for prognosis of progression in prostate cancer.

During an 8-year period, 1,065 serum specimens were collected from 79 patients with prostate cancer of stages B2 to D1 (group I) and 51 patients with newly diagnosed stage D2 prostate cancer (group II) to evaluate statistically the relative reliability of elevated tumor-associated markers for progressive disease in prostate cancer. Forty of the group I patients and 21 of the group II patients presented a clinical progression of disease during follow-up. With the use of Gail's modification of Cox's regression model, serial acid phosphatase (AcP), total alkaline phosphatase (TAP), bone alkaline phosphatase (BAP), prostatic acid phosphatase (PAP), and prostate-specific antigen (PA) were analyzed. Results from group I patients revealed that only PA (P = .0002) and PAP (P = .0684) were prognostically important markers for detection of imminent disease progression. However, all markers were prognostically important in group II patients. Comparative studies indicated that PA (P = .0052) and PAP (P = .0359) were the more reliable markers for group I patients, whereas PA (P less than .0001), BAP (P = .0007), and PAP (P = .0206) were the more reliable markers for group II patients. Multivariate analyses revealed that, after adjustment for the effect of PA, no other marker was significantly related to the risk of progression. Elevated PA levels were predictive of increased risk 6 months before disease progression in group I patients only (P less than .0001). Overall, the apparent order of prognostic reliability for disease progression was found to be PA greater than PAP greater than BAP greater than AcP greater than TAP.

Acid Phosphatase↗