PubMed Health⌕ Search

Biomedical subjects

J J Tai

Publications and source records attributed to J J Tai.

At least 19 recordsLinked to original sources
PubMed2001

Chromosome aberrations in lymphocytes of residents living in buildings constructed with radioactively contaminated rebars.

Using the G-banding technique, we examined lymphocytes from 90 individuals (43 males and 47 females, median age 31 years) living in buildings constructed with radioactively contaminated rebars. Forty-five nonexposed control subjects (22 males and 23 females, median age 30 years), matched to the radiation-exposed individuals by sex and age, were selected for comparison. At least 500 metaphases were checked for each individual. All recognizable structural aberrations of chromosomes or chromatids were recorded. After adjusting for age and smoking status, both the percentage of cells with aberrant chromosomes (PCAC) and the number of aberrant chromosomes per 100 cells (NAC) were found to be significantly higher in the radiation-exposed females than in the control females (p < 0.05 for PCAC and NAC). This difference, however, was not observed in the comparison of radiation-exposed and control males. This suggests a possible interaction between sex and radiation exposure in their effects on chromosome aberrations.

Adolescent↗
PubMed2001

Cryopreservation of gander semen.

1. The effect of dimethylacetamide (DMA) and dimethyl sulphoxide (DMSO) on the cryopreservation of gander semen were investigated. An improved survival rate of spermatozoa after freeze-thawing was obtained when semen was frozen by a fast-freezing procedure on dry ice with 9% DMA as the cryoprotectant. 2. Gander semen, which was frozen during mid season, was tested for fertilising ability in different times of the season. The percentage of fertility during d 3 to d 9 after 2 consecutive inseminations was 68% to 95%, depending on the date of artificial insemination.

Acetamides↗
PubMed2001

Identifying chromosomal fragile sites from a hierarchical-clustering point of view.

Identification of fragile sites is a way to investigate the genetic abnormalities that are the hallmark of cancer and play an important role in carcinogenesis. Manifestation of nonrandom breakage at a chromosome band is an essential criterion for determination of the fragility of the band. In this article, a new detection procedure is proposed. This new procedure takes the relationship of one site with the others into consideration and can be applied to tests of the randomness of breakpoints under either the proportional probability model (PPM) or the equiprobability model (EPM). The procedure can form a grouping structure that classifies all sites into several clusters. It is applied to identification of fragile sites for a real data set for Chinese patients with colorectal carcinoma for illustration of the proposed method.

Chromosome Banding↗
PubMed2001

Effects of implicit parameters in segregation analysis.

In human genetic analysis, data are collected through the so-called 'ascertainment procedure'. Statistically this sampling scheme can be thought of as a multistage sampling method. At the first stage, one or several probands are ascertained. At the subsequent stages, a sequential sampling scheme is applied. Sampling in such a way is virtually a nonrandom procedure, which, in most cases, causes biased estimation which may be intractable. This paper focuses on the underlying causes of the intractability problem of ascertained genetic data. Three types of parameters, i.e. target, design and nuisance parameters, are defined as the essences to formulate the true likelihood of a set of data. These parameters are also classified into explicit or implicit parameters depending on whether they can be expressed explicity in the likelihood function. For ascertained genetic data, a sequential scheme is regarded as an implicit design parameter, and a true pedigree structure as an implicit nuisance parameter. The intractability problem is attributed to loss of information of any implicit parameter in likelihood formulation. Several approaches to build a likelihood for estimation of the segregation ratio when only an observed pedigree structure is available are proposed.

Female↗
PubMed2000

Bias correction for segregation ratio estimation in human genetics.

Segregation ratio estimation has long been important in human genetics. A simple truncated binomial model is considered that assumes complete ascertainment and a deterministic genotype-phenotype relationship. A simple but intuitively appealing estimator of the segregation ratio, previously proposed, is shown to have a negative bias. It is also shown that the bias of this estimator can be largely reduced via a randomization device, resulting in a new estimator that has the same large-sample behavior but with a negligible bias (decaying at a geometric rate). Numerical results are given to show the small-sample performance of this new estimator. An extension to incomplete ascertainment is also considered.

Biometry↗
PubMed1999

Testing the nonrandomness of chromosomal breakpoints using highest observed breakages.

To determine whether a chromosomal band is a fragile site rather than a spontaneous breakpoint, an essential step is to test the nonrandomness of breakage at the region. In this paper, the nonapplicability of the testing procedure introduced by Bohm et al. is discussed, and a new detection procedure is proposed. This new procedure considers the relations of one site with the others, and can be applied to tests of the nonrandomness of breakpoints under either the proportional probability model, or the equiprobability model. A data set for Chinese patients with colorectal carcinoma is analyzed as an illustration of the proposed method.

China↗
PubMed1998

Chromosomal fragile site expression in lymphocytes from patients with schizophrenia.

Schizophrenia is a common complex mental disorder. The lifetime prevalence of this disease is about 1% across different populations. The etiology is still unknown despite decades of intensive study. This report is aimed at studying the relationship between chromosomal fragile sites and the etiology of schizophrenia. Lymphocytes of 72 schizophrenic patients and 66 healthy controls were cultured in M medium, which is deficient in folic acid, and in medium RPMI 1640 with distamycin A. G-banding was carried out on 100 metaphases of each individual. Fragile sites were characterized as specific chromosomal bands that exhibit nonrandom gaps or breaks. Culture in M medium resulted in significant differences in the total number of chromosomal lesions and the total number of cells with chromosomal lesions between patients and controls (P<0.001), while no difference was noted after exposure to distamycin A. In the case of M medium, 17 bands in both patients and controls were recognized as expressing fragile sites nonrandomly using a statistical method based on the relationship of the binomial and F distributions. Further analysis using Fisher's exact test revealed a significant excess of expression of a rare fragile site at 2q11.2 among patients compared with controls (P<0.05). In the case of distamycin A induction, 13 bands were identified as having nonrandom expression of fragile sites using the same statistical method. A significant excess expression of a fragile site at 9q12 was identified among patients compared with controls by applying Fisher's exact test (P<0.001). Thus, our data suggest that chromosomal bands 2q11.2 and 9q12 are interesting regions that may harbor important genes associated with schizophrenia.

Adult↗
PubMed1998

A confirmation analysis method for identification of chromosomal fragile sites.

Fragile sites are chromosome bands that do not manifest a presumed breakage pattern. Identification of fragile sites is a way to investigate the mechanism of carcinogenesis because the fragility at a specific chromosome position may be the causation of an associated cancer. A problem in the identification of fragile sites is the high false positive rate arising from simultaneously carrying out a large number of significance tests. To control it, we propose to find a reference study to confirm the identification result of an objective study. We utilize the Bayesian concept for linking two studies. Basically, our method demonstrates a conservative way to take account of the prior information of a binomial parameter. The derived estimate of breakage probability can be interpreted as a resampling weighted sample-pooling method. It is applied to confirm the identification of fragile sites for a data set of neuroblastoma patients.

Chromosome Banding↗
PubMed1998

Polymorphisms of the apolipoprotein B 3' variable number of tandem repeats region associated with coronary artery disease in Taiwanese.

We studied the allelic frequency of the variable number of tandem repeats region 3' of the apolipoprotein B gene (apoB 3' VNTR) and its impact on coronary artery disease (CAD) in 150 patients with CAD and 153 normal controls in a Taiwan population. apoB 3' VNTR alleles were classified according to the number of repeats of a 15-bp hypervariable elements (HVE), the sequence of which was determined using the polymerase chain reaction and direct sequencing. Thirteen alleles comprising from 26 to 54 HVEs were identified. The CAD patients had greater heterozygosity (0.58 vs 0.42) and a higher frequency of long (> 36-HVE) apoB 3' VNTR alleles than the controls (18.7% vs 10.8%, p < 0.01). CAD patients with two HVE-36 alleles and no HVE-32 alleles (the two most common forms) had significantly higher concentrations of LDL-cholesterol, apolipoprotein B, and triglycerides, and significantly lower values of HDL-cholesterol and apolipoprotein AI than the control group (p < 0.01 for all comparisons). The length of the apoB 3' VNTR was not correlated with the plasma concentrations of any of the lipids. We conclude that long apoB 3' VNTR alleles occur more frequently in CAD patients, but that apoB 3'VNTR genotypic variation has little impact on the risk of dyslipidemia in Taiwanese.

Aged↗
PubMed1997

Chromosomal study in lymphocytes from subjects living or working in buildings constructed with radioactively contaminated rebar.

It has recently been found that many buildings in Taiwan were constructed with radioactively contaminated rebar, which raised great concern among the residents as well as governmental officials. In order to investigate the possible cytogenetic damage to the residents of contaminated buildings, a G-banding method was carried out on the lymphocytes of 30 radiation-exposed individuals from four families and one office building, as well as 15 control individuals from laboratory personnel. The estimated cumulative radiation doses for the exposed people range from 19.63 to 280.50 mSv. Altogether, 13 females and 17 males belonging to the radiation-exposed group, and 7 females and 8 males in the control group, were included in this study. With the exception of one sample, at least 500 metaphase spreads were scored and analyzed for each individual. All the recognizable structural aberrations of chromosomes or chromatids were recorded and statistically analyzed. Comparison of either percentage of cells with chromosome aberrations or number of aberrated chromosomes per 100 cells between the radiation-exposed and the control groups manifested insignificant differences (p = 0.1145 and 0.0766, respectively). In addition, the chromosomal regions close to the centromere were found to break more frequently than elsewhere in the genome.

Adolescent↗
PubMed1997

Self-contained subsets method for estimation of gene frequencies of truncated genetic data.

The self-contained subsets method subdivides a genetic data set into a number of subsets from which estimates are computed. The advantage of such a method is that when a subset is suspected of containing unreliable data then discarding that subset will not invalidate the remaining subsets for estimation. Thus, the complicated computation required to deal with truncated data can be avoided. In this paper, using estimation of gene frequencies as an example for one subset case, the marginal distribution of a subset total is derived and then, using this distribution, the variance of the frequency estimate of a gene frequency from the subdivision method is calculated. The subdivision method is also applied to impute the number of people of a truncated group. Finally, more complex cases where there are multiple subsets available for estimation are discussed. Results are compared to those of previous studies.

Gene Frequency↗
PubMed1995

Restriction fragment length polymorphisms of apolipoprotein B gene in Chinese population with coronary heart disease.

Three restriction fragment length polymorphisms (RFLPs), EcoRI (R), Xbal (X), and Mspl (M) of the apolipoprotein (apo)B gene, were studied to determine their distribution frequencies and influence on the lipid profiles in 148 Chinese patients with documented coronary heart disease (CHD) and in 153 healthy subjects. The plasma concentrations of cholesterol and apoB showed no difference between the CHD patients and controls. However, CHD patients had significantly higher concentrations of low-density lipoprotein cholesterol and triglyceride and lower concentrations of high-density lipoprotein cholesterol than the controls. The frequencies of these three apoB RFLPs did not differ between the CHD patients and controls. Compared with South Asians and Caucasians, the Chinese in Taiwan showed a much lower frequency of R-, X+, and M- alleles. There was no evidence of an association between lipid profiles and RFLPs in either CHD patients or controls. The weak association of EcoRI, Xbal, and Mspl polymorphisms of the apoB gene with CHD indicates that the three RFLPs cannot be used as a predictor for the risk of CHD in the Chinese population.

Aged↗
PubMed1994

A non-excluded set method for the calculation of paternity probability.

Forensic judgment of paternity depends on genetic and nongenetic evidence. Sometimes genetic marker tests can provide clear evidence to exclude a falsely accused man, but they do not always succeed. On the other hand, if the accusation is true, the alleged father will not ever be excluded by genetic marker tests. When a nonexclusion case occurs after one or more marker tests, a report of paternity probability is required in the court. The current methods for calculating the paternity probability are the "paternity index method" and the "nonexclusion method." A number of recent articles have openly debated the fallacies, validity and utility of both methods. This paper briefly reviews the two methods and proposes a non-excluded set method along with examples for illustrating the various patterns of paternity probabilities of the three methods.

Forensic Medicine↗
PubMed1993

A method for testing the nonrandomness of chromosomal breakpoints.

Testing the nonrandomness of breakage at a chromosome band is an essential step fo identifying a fragile site. In this paper, we propose a method derived by using the relationship between the binomial and F distributions for testing nonrandomness. The method is simple in calculation. It was applied to the detection of fragile sites for Chinese patients with colorectal carcinoma.

Carcinoma↗
PubMed1991

Linkage disequilibrium and linkage information from one-child families.

In linkage analysis a single-child family is usually considered to be completely uninformative. This article shows that such a family can provide information on linkage disequilibrium, even if it provides no information on linkage equilibrium. A transition matrix consisting of the recombination fraction and the phase proportion is proposed to study the genetic transmission from a pair of parents to their single child. The information about linkage for a single-child family is shown to be confounded by the phase proportion. This explains why such a family used to be considered uninformative under the assumption of linkage equilibrium. By reparametrizing the recombination fraction and the phase proportion into one parameter, it is demonstrated that extracting information on linkage disequilibrium is feasible. The study of power of the testing method proposed here is carried out by simulation.

Child↗
PubMed1990

Human leukocyte antigens in inhabitants of Taiwan.

Human leukocyte antigens (HLA) were investigated in 200 healthy Taiwan inhabitants of Taiwanese (46 persons), Hakka (36), Tai-Ya Tribe (28) Pu-Long Tribe (30) Pai-Wan Tribe (30) and Lu-kai (30) descent. In those of Taiwanese and Hakka descent, HLA-A11 and A2 were the two most frequently seen human leukocyte antigens. HLA-A11 was seen in 69.6% in those of Taiwanese descent and 61.1% in those of Hakka descent. HLA-A2 was seen in 50.0% of the Taiwanese and 44.4% of the Hakka. For the B loci, B40 (Taiwanese, 43.5%; Hakka, 44.4%), Bw46 (Taiwanese, 28.3%; Hakka, 19.4%) and B13 (Taiwanese, 15.2%; Hakka, 30.6%) were the most common antigens. For the C loci, Cw3 (Taiwanese, 57.1%; Hakka 64.9%), Cw1 (Taiwanese, 28.6%; Hakka, 35.1%) and Cw7 (Taiwanese, 40.5%; Hakka, 29.9%) were commonly seen antigens. The most commonly detected antigens for the DR loci were: DR2 (Taiwanese, 45.1%; Hakka, 56.8%) and DR4 (Taiwanese, 37.3%; Hakka, 32.4%). These results disclose that no major human leukocyte antigenic differences exist between the two aforementioned groups in this study. In addition, there are no major differences in Taiwanese and Hakka descent, and those of south and north mainland Chinese descent. All bear some antigenic similarities. However, for aborigines, the original inhabitants of Taiwan, the HLA antigens are significantly different from the Han Chinese as a whole. Characteristic features are seen in A24, Bw60, DRw6 and DRw8. In the meantime, a high frequency of common antigens are shared among the tribes and consequently a large number of blank alleles are seen in the aborigines. This reflects the homozygosity effect which is often seen in an isolated society.

Adolescent↗
PubMed1990

Pseudo-random mating systems for 3-allele loci.

A random mating population attains equilibrium by the Hardy-Weinberg law. By demonstrating some simple examples for 2-allele loci, Li (1988) showed that a nonrandom mating population of certain mating patterns may also attain equilibrium. He called such a type of population a pseudo-random mating population. Tai (1990), then, gave a generalized representation of these pseudo-random mating systems. In this paper the clear patterns of pseudo-random mating behavior for a 3-allele locus are derived. Both autosomal and sex-linked systems are discussed. The study of these mating patterns provides a way to understand the complicated mating system of a population, which usually is only with difficulty realized through sampled individuals from that population.

Alleles↗