A pooling procedure for life-test data

A preliminary-test shrinkage estimator for the scale parameter in pooling data from extreme-value distributions is proposed. The optimum values of shrinkage coefficients for the preliminary-test shrinkage estimator are obtained based on a regret function. The optimum values of shrinkage coefficients and the critical values for the preliminary test are tabulated for several sample sizes. For a mean square error criterion of goodness of estimation, the preliminary-test shrinkage estimator is preferable to the usual preliminary-test estimator     

Surgical treatment of vertebral and posterior inferior cerebellar artery aneurysms

Geochelone carbonaria hemoglobin (Hb) was analyzed by polyacrylamide gel electrophoresis (PAGE) and purified by ion exchange chromatography on CM-cellulose. Seven fractions were obtained using fresh Hb preparations. CM-cellulose chromatography of Hb reacted with iodoacetamide, showed one minor (HbI) and one major band (HbII). Analysis of the molecular masses of recently collected Hb and of aged solutions determined by gel filtration showed that polymerization increased with the duration of storage. The reaction with oxidized glutathione changed the electrophoretic pattern of Hb, and highlighted the bands corresponding to glutathionyl-Hb. The presence of these bands in fresh Hb solutions and in alkylated preparations suggests that they may occur in vivo. PAGE under dissociating conditions showed that the hemolysate contained 3 different polypeptide chains (G1, G2 and G3). Both Hb components shared the G1 globin chain with HbI containing G1 and G2 and HbII, G1 and G3 chains.     

Prevalence of pyruvate kinase deficiency among the Chinese: determination by the quantitative assay

The prevalence of pyruvate kinase (PK) deficiency among the Chinese population has not been established. Fung et al. (Arch Dis Child 44:373-376, 1969) and Wu et al. (Am J Hematol 20:139-144, 1985) indicate 3.4% and 2.1% PK deficiency prevalence rates, respectively, the higher figure based on Beutler's screening test [3] without confirmatory testing. Neither figure is consistent with the occurrence of hemolytic anemia from this cause in the experiences of hematologists in Hong Kong. Using the standard quantitative assay, we measured PK activity in blood samples from 1,100 local Chinese people. The assay was automated on a centrifugal analyser, and the results were expressed in IU per gram of hemoglobin (IU/g Hb). Blood samples from 497 healthy male adults were measured, and PK activity was found to have a range of 15.2 +/- 5.2 (mean +/- 2 SD). A total of 100 cord blood samples were also measured, and the reference interval for this subgroup was 17.7 +/- 4.8. Additionally, samples from 503 anaemic patients were measured, and all were found to have values above the lower limit of the reference interval. The prevalence of PK deficiency among the Hong Kong Chinese population determined by this study was < 0.1%.     

Color Doppler ultrasound used for screening varicocele: the clinical significance as compared to physical examination

Here we present an enzyme-linked immunosorbent assay (ELISA) on microtiter plates for the quantitative determination of anti-D. This method is based on the solubilization of red blood cells sensitized with anti-D and the subsequent measurement of immunoglobulin G by ELISA. The measuring range of the assay is 40-5,000 IU/ml and the lowest quantifiable concentration in plasma is 0.5 IU/ml. The interassay relative standard deviation for concentrations above 130 IU/ml ranges from 3.2 to 8.1% and below 50 IU/ml from 10.5 to 19.7%. Comparison of ELISA with automated hemagglutination shows that the results of the two assays correlate well: r = 0.992, n = 26. The assay was validated for donor plasma samples and anti-D immunoglobulin preparations and it can also be used in assessing the severity of Rh (D) hemolytic disease during pregnancy.     

Conformational studies of paclitaxel analogs modified at the C-2' position in hydrophobic and hydrophilic solvent systems

The conformations of two paclitaxel analogs modified at the C-2' position, 2'-deoxypaclitaxel and 2'-methoxypaclitaxel, were studied in hydrophobic and hydrophilic solvent systems by a combination of NMR spectroscopy, CD measurements, and molecular modeling. Both analogs have hydrophobic and hydrophilic conformations that resemble those of paclitaxel itself in the same media. Since the two have diminished biological activities in a number of bioactivity assays and the hydrogen-bonding capability of the 2'-hydroxyl group has been eliminated, we postulate that this group is involved in hydrogen bonding with tubulin and plays an important role in molecular recognition. The results of this study are in agreement with our earlier report on paclitaxel 2'-acetate, an analog in which the 2'-hydroxyl group hydrogen-bonding capacity has also been eliminated.     

Longitudinal determinants of bronchial responsiveness to inhaled histamine

BACKGROUND AND STUDY OBJECTIVE: The point prevalence of bronchial hyperresponsiveness (BHR) is imperfectly associated with current asthma, possibly due to changes over time in bronchial responsiveness (BR). To evaluate cross-sectional and longitudinal determinants of BR, a population sample comprising 408 children and adolescents, aged 7 to 17 years at enrollment, was examined twice, 6 years apart. METHODS: Case history was obtained by interview and questionnaire. BR to inhaled histamine, pulmonary function, and skin prick test reactivity were measured using standard techniques. RESULTS: The point prevalence of BHR (the concentration of histamine causing a 20% decline in FEV1 <8 mg/mL) declined from childhood to early adulthood (25% and 6%, respectively; p<0.001); and similarly a decline in histamine dose-response slope was observed. At both surveys, prechallenge FEV1 percent predicted, asthma, and atopy, especially atopy to house dust mite (HDM), were important determinants for the degree of BR. After adjustment for prechallenge FEV1 percent predicted, no male-female difference was observed in degree of BR. Lower FEV1 percent predicted (p=0.003), asthma (p<0.001), higher degree of BR (p=0.003), and atopy to HDM (p=0.007) at enrollment predicted a higher degree of BR at the second survey (degree of BR at second survey adjusted for prechallenge FEV1). Furthermore, new asthma (p<0.001) and/or atopy to HDM (p=0.003) were associated with higher BR at the second survey. Confining the analysis to nonasthmatics showed that subjects with new or persistent atopy to HDM had significantly increased BR compared with nonatopic subjects; and, moreover, prechallenge FEV1 percent predicted was significantly correlated with BR. CONCLUSIONS: BR declines from childhood to early adulthood, possibly reflecting the increase in airway caliber. The level of FEV1 and atopy, especially to HDM, are important determinants for changes over time in level of BR, also in nonasthmatic subjects.