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Biomedical subjects

D Lai

Publications and source records attributed to D Lai.

At least 37 records · Page 2Linked to original sources
PubMed2000

Standardized mortality ratio and life expectancy: a comparative study of Chinese mortality.

BACKGROUND: Various models have been proposed for rapid conversion of the standardized mortality ratio (SMR) to life expectancy using data from developed countries. METHODS: We compared two methods for converting the SMR to life expectancy using mortality data from the largest developing country, China. RESULTS: The first model, using the Gompertz function, does not provide a good fit to the life expectancy and SMR of China. The regression lines derived from the second, a log-linear model using parameters estimated from the US white population are not a good fit to Chinese males and older females. However, if the parameters in the log-linear model are estimated using Chinese mortality data, the resultant regression lines fit the data reasonably well. CONCLUSION: The relationship between life expectancy and SMR based on mortality data from developed countries may not be valid for developing countries. Based on our empirical study, separate estimates of the coefficients of the model are required for developing countries.

Adult↗
PubMed2000

Functional role of residues corresponding to helical domain II (amino acids 35 to 46) of human immunodeficiency virus type 1 Vpr.

Vpr, encoded by the human immunodeficiency virus type 1 genome, contains 96 amino acids and is a multifunctional protein with features which include cell cycle arrest at G(2), nuclear localization, participation in transport of the preintegration complex, cation channel activity, oligomerization, and interaction with cellular proteins, in addition to its incorporation into the virus particles. Recently, structural studies based on nuclear magnetic resonance and circular dichroism spectroscopy showed that Vpr contains a helix (HI)-turn-helix (HII) core at the amino terminus and an amphipathic helix (HIII) in the middle region. Though the importance of helical domains HI and HIII has been defined with respect to Vpr functions, the role of helical domain HII is not known. To address this issue, we constructed a series of mutants in which the HII domain was altered by deletion, insertion, and/or substitution mutagenesis. To enable the detection of Vpr, the sequence corresponding to the Flag epitope (DYKDDDDK) was added, in frame, to the Vpr coding sequences. Mutants, expressed through the in vitro transcription/translation system and in cells, showed an altered migration corresponding to deletions in Vpr. Substitution mutational analysis of residues in HII showed reduced stability for VprW38S-FL, VprL42G-FL, and VprH45W-FL. An assay involving cotransfection of NLDeltaVpr proviral DNA and a Vpr expression plasmid was employed to analyze the virion incorporation property of Vpr. Mutant Vpr containing deletions and specific substitutions (VprW38S-FL, VprL39G-FL, VprL42G-FL, VprG43P-FL, and VprI46G-FL) exhibited a negative virion incorporation phenotype. Further, mutant Vpr-FL containing deletions also failed to associate with wild-type Vpr, indicating a possible defect in the oligomerization feature of Vpr. Subcellular localization studies indicated that mutants VprDelta35-50-H-FL, VprR36W-FL, VprL39G-FL, and VprI46G-FL exhibited both cytoplasmic and nuclear localization, unlike other mutants and control Vpr-FL. While wild-type Vpr registered cell cycle arrest at G(2), mutant Vpr showed an intermediary effect with the exception of VprDelta35-50 and VprDelta35-50-H. These results suggest that residues in the HII domain are essential for Vpr functions.

Amino Acid Sequence↗
PubMed2000

Life table analysis of ascariasis in a rural community in Jiangxi Province, China.

The prevalence of ascariasis is very high in parts of rural areas in southern China. The high prevalence of ascariasis is one of the most neglected public health problems. A longitudinal investigation on the prevalence of ascariasis in a rural community in China was reported previously. In this article, we re-analyze the reported age specific prevalence of ascariasis using a life table method. The results from our analysis may provide a better summary of the impact of the disease on the studied population.

Adolescent↗
PubMed1999

Nail-patella syndrome and IgA nephropathy in a Chinese woman.

Nail-patella syndrome (NPS), also known as hereditary onycho-osteodysplasia, is an autosomal dominant pleiotropic disorder characterized by nailbed dysplasia or hypoplasia, absent or hypoplastic patellae, iliac horns and deformation or luxation of the radial head. Nephropathy is a known serious complication associated with NPS. In this report, we describe an adult Chinese woman with the clinical and radiological features of NPS who presented with the nephrotic syndrome. Renal biopsy disclosed focal segmental glomerulosclerosis on light microscopy, while immunofluorescence revealed predominant staining for IgA in the glomerular mesangium and along some capillary walls. Ultrastructural study confirmed the presence of paramesangial deposits as well as subendothelial collagen fibrils in the glomeruli. The histological findings were those of combined NPS and IgA disease, an association which has rarely been described.

Adult↗
PubMed1999

Potential gains in life expectancy or years of potential life lost: impact of competing risks of death.

BACKGROUND: Measuring the impact of competing risks of death on society is important for setting public health policy and allocating resources. However, various indicators may result in inconsistent conclusions. The potential gains in life expectancy (PGLE) by elimination of deaths from HIV/AIDS, diseases of the heart and malignant neoplasms were compared to the years of potential life lost (YPLL) due to these causes in measuring the impact of premature death for the US population of working age (15-64 years). METHODS: The PGLE and the YPLL were computed from mortality reports (1987-1992) by race and gender group for deaths from HIV/AIDS, diseases of the heart and malignant neoplasms for the US population of working age. RESULTS: The YPLL overestimated the importance of premature deaths from HIV/AIDS compared to the PGLE. For the total US population and total US white population of working age, the YPLL were about 20-30% higher than the PGLE. However, the YPLL were about 20-30% lower than the PGLE for the US black population of working age. Furthermore the relative importance of the impact of death from various diseases may be interchanged by these two indicators. For example, for US black males of working age, the impact of deaths from HIV/AIDS by PGLE in 1992 was higher than that from malignant neoplasms and lower than that from diseases of the heart, but by using YPLL, the impact of premature deaths from HIV/AIDS was higher than that from both diseases of the heart and malignant neoplasms. CONCLUSIONS: The PGLE by elimination of deaths from diseases takes into account the competing risks on the population and it can be compared easily across populations. The YPLL is an index that does not take into account competing risks and it is also heavily influenced by the age structure and total population size. Although there are several standardization techniques proposed to improve the comparability of the YPLL across different populations, the YPLL fails to address the central issue of competing risks operating on the population. For this reason, we prefer the PGLE to the YPLL in measuring the impact of premature deaths on a population.

Acquired Immunodeficiency Syndrome↗
PubMed1999

[The regulation of estrogen and tamoxifen to bcl-2 oncogene in endometrial carcinoma].

OBJECTIVE: To study the regulation mechanisms of bcl-2 oncogene in endometrial carcinoma. METHODS: A reverse transcription-polymerase chain reaction (RT-PCR) method was utilized to quantitate bcl-2 mRNA levels which regulated by estrogen(17-beta-estradiol) and tamoxifen in estrogen receptor (ER)(+) RL-952 endometrial carcinoma cells. RESULTS: bcl-2 mRNA level was detected in ER(+) RL-952 cells. 17-beta-estradiol stimulated a concentration-dependent increase in bcl-2 mRNA level, while tamoxifen lead to a concentration-dependent decrease in bcl-2 mRNA level. CONCLUSIONS: bcl-2 oncogene expression in ER(+) endometrial carcinoma is regulated by estrogen and antiestrogen. Estrogen may up-regulate the cell bcl-2 level to inhibit cell apoptosis, while tamoxifen may down-regulate the cell bcl-2 level and induce apoptosis.

Carcinoma↗
PubMed1999

[Efficacy of 40-O-(2-hydroxyethyl)-rapamycin in preventing chronic renal allograft rejection in rats].

OBJECTIVE: To study the efficacy of 40-O-(2-hydroxyethyl)-rapamycin (SDZ RAD) in preventing chronic renal allograft rejention in rats. METHODS: The rat model of chronic renal allograft rejection was made with micro-surgery. The recipients were divided into two groups. The recipients in the study group were treated with SDZ RAD at a dose of 0.5 mg x kg(-1) x d(-1) by means of gavage and the controls with vehicle. RESULTS: After 24 weeks of treatment, proteinuria, glomerular sclerosis, vascular intimal thickening and the infiltration of monocytesmacrophages and lymphocytes in the study group were decreased, in consistence with the reduced expression of ICAM-1, VCAM-1, TGF-beta(1) and PDGF-AA mRNA. CONCLUSION: It is suggested that SDZ RAD can prevent chronic renal allograft rejection and the reduced expression of above adhesion molecules and growth factors may be involved in the mechanism.

Animals↗
PubMed1998

Serial proton magnetic resonance spectroscopic imaging, contrast-enhanced magnetic resonance imaging, and quantitative lesion volumetry in multiple sclerosis.

Serial magnetic resonance (MR) studies that included proton MR spectroscopic imaging (MRSI), contrast-enhanced MR imaging (MRI), and lesion volumetric studies were performed on 25 multiple sclerosis (MS) patients with mild to modest clinical deficits. Each patient was scanned at varying intervals for up to 2 years, resulting in a total of 124 usable MR sessions. In these longitudinal studies, metabolic changes were observed on MRSI for some subjects before the appearance of lesions on MRI scanning. Regional changes in metabolite levels were observed to be dynamic and reversible in some patients. Transient changes in N-acetylaspartate (NAA) levels were sometimes found in acute plaques and indicate that a reduced NAA level does not necessarily imply axonal loss. An inverse correlation between the average NAA within the spectroscopic volume and the total lesion volume in the whole brain was observed. This negative correlation implies that NAA can serve as an objective marker of the disease burden. Strong lipid peaks in the absence of gadolinium enhancement and MRI-defined lesions were observed in 4 patients. This observation suggests that demyelination can occur independent of perivenous inflammatory changes and supports the presence of more than one pathophysiological process leading to demyelination in MS.

Adult↗
PubMed1998

Health care service use by Chinese seniors in British Columbia, Canada.

This paper assesses whether the same factors are predictive of health service utilization among this ethnic group as is true of the general population of seniors. The data suggest that the health of Chinese elders is just as bad as other seniors, and their utilization is very similar. They have a strong preference for Western over Chinese medicine and for Western trained doctors over Chinese practitioners, and use services with Chinese staff, probably because of language. Similarly, the predictors of service use are strikingly similar to predictors revealed in utilization studies throughout the industrialized world. Ability to speak English, immigration history, and country of origin are unrelated to the use of these services. However, approximately half of Chinese seniors also engage in traditional Chinese care. Religious beliefs and a preference for traditional Chinese medicine are strongly predictive of the use of traditional care. It would appear that distinctive culture is related to the use of traditional care, but not the use of the western health care system.

Journal Article↗
PubMed1998

[The timing and mode of surgery in patients with severe acute pancreatitis].

OBJECTIVE: To investigate the timing and mode of surgical management in patients with severe acute pancreatitis (SAP). METHOD: The timing, mode of operation and mortality were reviewed retrospectively in 50 SAP cases undergoing laparotomy in our hospital from 1985 to 1994. RESULT: The overall mortality was 14% and 85.7% of the mortality falls on the age between 40 to 60 years, with no difference in etiology and sex. The operative mortality reduced gradually in patients with longer duration of illness (P > 0.05). The operative mortality of 31.8% in patients undergoing laparotomy within 12 h after hospitalization was significantly higher (P < 0.05) than in these operated on later. When the number of injured extra-pancreatic organs increased, the mortality also increased significantly (chi(2) = 5.99, P < 0.05). The related mortality with shock, pancreatic necrosis and multiorgan failure (MOF) was 31.8%, 31.6% and 28%, respectively (P < 0.05). The main procedures of surgical management were pancreatic debridement and/or drainage, and combined surgical measures. CONCLUSION: The laparotomy timing is an important factor influencing mortality as well as the severity of pancreatic necrosis, sepsis, and MOF. Delayed laparotomy and 24 h preoperative management is recommended. Surgery adopted should be simple, efficient in drainage and debridement.

Adolescent↗
PubMed1997

Balance in children with otitis media with effusion.

To determine the presence of balance disorders in young children who had otitis media with effusion (OME), 25 subjects, aged 13-57 months, diagnosed by pediatric otolaryngologists, were tested on the gross motor subtest of the Peabody Developmental Motor Scales, a standardized test of motor development with established norms. Parents also filled out questionnaires about their children's balance skills. Subjects with unilateral disease did not differ significantly from normals. Subjects with bilateral disease, however, were significantly impaired compared to normals on balance, locomotion and total score and they were significantly impaired compared to unilateral subjects on all scores. Parental perceptions of their children's balance correlated poorly with the test results. These data suggest that young children with bilateral otitis media with effusion are delayed in developing motor skills that require dynamic balance. Therefore, in spite of a negative history for balance problems physicians should consider balance performance when developing a treatment plan. Children with balance impairments might benefit from more aggressive intervention.

Child, Preschool↗
PubMed1997

Indium as internal standard in square wave anodic stripping analysis of lead in blood with microelectrode arrays.

The toxic effects of lead on humans, especially children have been well documented. ASV has been an important technique in the analysis of lead in blood of humans. This research has demonstrated that indium(III) can be used as an internal standard in the analysis of lead in blood samples with mercury film microelectrode arrays. Indium is a good choice because of a low endogenous blood concentration and because baseline separation of anodic stripping peaks among Cd, In, and Pb can be achieved under appropriate conditions. The concentration of sodium bromide strongly influences the resolution of these metals and the sensitivity of ASV to In(III) in solution. Square wave anodic stripping voltammetry together with screen-printed microelectrode arrays showed that the ratio of the anodic stripping peak currents of Pb and In varies linearly with the concentration of Pb in blood samples ranging from 1.2 to 30.0 micrograms/dL. The average intraassay precision (rsd) was 6.7%.

Electrochemistry↗
PubMed1997

Impact of HIV/AIDS on life expectancy in the United States.

OBJECTIVES: The potential gains in life expectancy of the US population by the partial and total elimination of deaths from HIV/AIDS were compared with that of deaths from heart disease and malignant neoplasms. METHODS: The data from the 1992 advanced mortality report and detailed information provided by the National Center for Health Statistics were analysed by using the partial multiple decrement life-table technique. RESULTS: For the total population of the United States in 1992, the gains in future life expectancy through the elimination of deaths from HIV/AIDS, heart disease and malignant neoplasms were 0.34, 3.25 and 3.21 years, respectively. The gains in life expectancy in those of working age 15-64 years) through the elimination of deaths from these three causes of deaths were 0.20, 0.40 and 0.55 years, respectively. Race/sex-specific calculations indicate that the total elimination of deaths from HIV/AIDS, heart disease and malignant neoplasms in white men of working age resulted in increased life expectancy of 0.28, 0.54 and 0.53, respectively, whereas the corresponding figures for black men were 0.82, 0.90 and 0.76 years, respectively. Although the impact of the elimination of the other causes remained relatively stable from 1987 to 1992, the potential gains in life expectancy for black men of working age by eliminating HIV/AIDS rose from 0.36 years in 1987 to 0.82 years in 1992. For the total US population of working age, the elimination of HIV/AIDS deaths resulted in increased life expectancy similar to that observed for a 50% reduction of heart disease or malignant neoplasms, whereas among black men of working age, the increased years of life expectancy from the elimination of HIV/AIDS deaths were virtually the same as those observed for the elimination of heart disease or malignant neoplasms. CONCLUSIONS: The potential gains in life expectancy by reduction of deaths from heart disease and malignant neoplasms are more heavily influenced by increasing years after the working ages (15-64 years), whereas the potential gains in life expectancy by reducing deaths from HIV/AIDS make a greater contribution to those of working age. Hence, in terms of the economic costs and benefits, these results indicate that in evaluating policy issues regarding allocation of research funds, studies of life expectancy are far more important than the simple approach which allocates funds on the basis of the number of deaths due to various diseases.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Spatial statistical analysis of Chinese cancer mortality: a comparison study of the D statistic.

In this paper, we study a nonparametric spatial pattern test statistic, the D statistic. The D statistic is an effective test statistic for testing spatial patterns in regional health data. Comparison studies of the D statistic with fixed weights and random weights are illustrated on the atlas of the Chinese cancer mortality rates and on other cancer atlas. Some social, economic and environmental reasons for statistically significant spatial autocorrelations of the Chinese cancer mortality rates were given in the discussion section. The method for calculating the mean and the variance of the randomly weighted D statistic is given in the appendix.

China↗
PubMed1997

[Application of gas chromatography to identification of Clostridium difficile].

With chromatograph produced in our country, the gas chromatograms of fatty acid metabolites of five strains of Clostridium difficile isolated from stool of patients with tumor and one strain for control were compared and analysed by using stainless steel chromatographic column, 15% modified polyethylene glycol stationary phase nitrogen carriergas 140 degrees C column temperature and 190 degrees C detector temperature. The chromatograms of the isolated strains and the control strain were found to be extremely similar. All of them were peaks of acetic, propionic, isobutyric, butyric, isovaleric, valeric, and isocaproic acid. In comparison, the peaks of acetic, butyric, and isocaproic acid were higher, those of the isobutyric and isovaleric acid were medium and those of propionic and valeric acid were lower. Moreover, a low, flat peak appeared at 14th minute and was similar to that of p-cresol reported by Berg et al. The results of our experiment revealed that gas chromatography may be used as a simple, quick method for the identification of Clostridium difficile.

Chromatography, Gas↗