The stage-dependent inhibitory effect of porcine follicular cells on the development of preantral follicles.

The objective of this study was to examine the effects of follicular cells on the in vitro development of porcine preantral follicles. In Experiment 1, one preantral follicle alone (Trt 1) was cocultured with a follicle of the same size with oocytes (Trt 2) or without oocytes (Trt 3). Preantral follicles cultured alone in vitro for 12 days had greater follicle diameters (1017 +/- 96 microm versus 706 +/- 69 or 793 +/- 72 microm, P < 0.05), growth rates (201 +/- 0.3 versus 103 +/- 0.2 or 128 +/- 0.2, P < 0.05) and oocyte survival rates (73% versus 48, or 25%, P < 0.05) than other groups. The inhibitory effects of follicle cells on the growth of preantral follicles and oocyte survival rates were not enhanced by the addition of oocytectomized preantral follicles (Experiment 2). Follicles were cocultured with different sources of follicular cells in other experiments. Coculture with cumulus cells enhanced oocyte survival compared to the control (without coculture) and mural follicular cell groups (Experiment 3). The growth and survival rates of oocytes collected from the group of follicles cocultured with cumulus cells from large antral follicles (>3 mm) were greater (P < 0.05) than those from small antral follicles (<3 mm), or than the control group (without cumulus cells, experiment 4). No significant differences in the follicular diameters (674 +/- 30 microm versus 638 +/- 33 and 655 +/- 28 microm) and growth rate (105% versus 94 and 105%) were observed among the preantral follicles of the different treatments (P > 0.05). Taken together, coculture with the cells from large antral follicles (>3 mm) exerted a significant positive effect on oocyte survival. The growth and oocyte survival of preantral follicle cocultured with the same size of follicles (with or without oocyte) were inhibited. Growth and survival rates of preantral follicles and oocytes are improved by coculturing them with the cumulus cells derived from larger antral follicles.

Isolation and characterization of phytochelatin synthase in rice seedlings.

Rice plants were treated with 50 microM copper sulfate to induce the synthesis of phytochelatins by means of a series of enzymatic reactions, including that of photochelatin synthase. Phytochelatin synthase extracted from 3-week-old rice seedlings was purified through a series of steps including precipitation with ice-chilled acetone, QAE A-50 anion exchange column, Amicon XM-50 ultrafiltration and Polybuffer Exchange (PBE) 94 chromato-focusing. This enzyme had a molecular mass of about 100 kDa with an isoelectric point of 4.0. The temperature and pH optima of this enzyme were 55 degrees C and pH 7.5, respectively. The enzyme was thermal tolerable and unstable under refrigeration at 4 or -20 degrees C. Cadmium was the most effective stimulator, followed by lead, copper, silver, cobalt and other divalent cations. Calcium and magnesium had no effect.

Loss of heterozygosity of p53 gene of oral cancer detected by exfoliative cytology.

The p53 tumor suppressor gene is a 16-20-kb section of cellular DNA located on the short arm of human chromosome 17 at position 17 P 13.1. Allelic deletions and/or point mutations in p53 gene are now known to be associated with the development of carcinogenesis. A hallmark of p53 is that both alleles are generally altered during transformation, which usually represents a loss of heterozygosity (LOH). In this study 30 normal dental students and 22 oral cancer patients were collected from the affiliated hospital of Chung Shan Medical and Dental College, Taichung, Taiwan. Extractions of DNA from the buccal mucosa or cancer surface were sampled by cytology brush. The two polymorphic restriction sites exon 4 and intron 6 within the p53 gene were amplified with polymerase chain reactions followed by restriction fragment length polymorphism assay. In heterozygous individuals, 66% of oral cancers demonstrated loss of p53 gene heterozygosity at the exon 4 site, and 50% showed LOH at the intron 6 site. These results indicate that inactivation of p53 gene is associated with development and/or progression of oral cancer. The essential advantages of oral exfoliative cytology are the non-invasiveness, painlessness, rapidity, ease and cost-effectiveness of cell sampling and DNA extraction. Furthermore, this experimental assay might be useful for preliminary screening of carcinogenesis in human beings.

Determinants of fast repeat migrations of the labor force: evidence from the linked national survey data of Taiwan.

"The main objectives of this paper are (1) to identify the determinants of job-related fast repeat migrations of individuals in the civilian labor force of Taiwan, and (2) to examine whether the effects of these determinants are largely consistent with the existing theories and with the findings of other empirical studies. Our study is based on the linked microdata of the annual national migration surveys of Taiwan from 1980 through 1989.... We review the main theories of repeat migrations and formulate a set of hypotheses that can be tested against the Taiwanese data."

Neurologic and ophthalmologic findings in children exposed to cocaine in utero.

We studied a cohort of 73 children exposed to cocaine in utero to characterize the spectrum of neurologic and ophthalmologic abnormalities; 36 children with no documented in utero drug exposure were selected as a control group. Most referrals of cocaine-exposed children to the child neurologist were made in the 1st year of life (81%). Reasons for referral were hypertonia (29%), seizures (22%), developmental delay (11%), tremulousness (11%), and hypotonia (4%). The most common abnormal finding in the cocaine-exposed children was hypertonia/hyperreflexia (63%), which was rarely seen in the control group. In addition, hypertonia/hyperreflexia was underdiagnosed by referring physicians. Similarly, hypotonia was seen on neurologic examination of cocaine-exposed children more frequently than documented by referral (16% versus 4%). Hypotonia was rarely seen in the control group. Twelve (43%) of 28 cocaine-exposed children seen by a pediatric ophthalmologist had structural ophthalmologic abnormalities. Neurologic and ophthalmologic findings suggesting structural lesions of the nervous system must be considered in cocaine-exposed children.

Clandestine labor migration to Taiwan.

"Illegal migration to Taiwan is a recent phenomenon but with a rapid rate of increase. Most illegal foreign workers enter on visitor's visas and overstay. This paper's detailed analysis of official data reveals that Malaysia, Philippines, Indonesia and Thailand are the major sources, providing a stock of mostly male workers numbering around 40,000. Sociodemographic and attitudinal changes among Taiwanese workers coupled with labor shortages in low-skilled jobs are pressuring the Taiwanese government to formulate plans for a systematic importation of foreign labor."

Frequency and structure of p53 rearrangements in human osteosarcoma.

Osteosarcoma is the most frequent childhood bone cancer (Tebbi, C. K., and Gaeta, J. Pediatr. Ann., 17:285-300, 1988). Using Southern blot mapping, we found that 11 of 60 (18%) osteosarcomas had altered restriction patterns of the p53 gene and that six of these had loss of the other p53 allele. In contrast, no alteration of the p53 gene was detected in 50 samples from other types of sarcomas. Fifty % of osteosarcoma cell lines (4 of 8) also had gross rearrangements of one p53 allele with loss of the second allele, and these had no detectable p53 mRNA. Osteosarcoma cell lines with no detectable alteration of the p53 gene contained abundant p53 transcripts. Taken together, data show that human osteosarcomas can have rearrangements of the p53 gene; these rearrangements may cause loss of normal constraints on cellular growth.

[An epidemiological study of oral cancer in Taiwan].

Southeast Asia, which includes Taiwan, has one of the highest incidences of oral cancer in the world. From a public health or a clinical dental viewpoint, it is important to study the epidemiologic characteristics of oral cancer in Taiwan. This paper presents epidemiologic data on oral cancer in Taiwan from 1981-1986. The data, gathered from Cancer Registry Center, Department of Health, Executive Yuan, ROC, is studied using the descriptive method. The age-standardized incidence rates for males and females were 4.45/100,000 and 1.42/100,000, respectively. The cumulative incidence rate (0-79 years) was 0.59% for males and 0.19% for females, respectively. The average age was 52.0 years for males and 53.4 years for females. The male/female ratio was 3:1. The most frequently affected sites were the tongue for males and major salivary glands for females. The incident rates were found to be significantly higher in central Taiwan, especially for males. Epidermoid carcinoma was the most common histopathologic type of oral cancer for both sexes.

[Harlequin fetus--a case report].

A one-day-old male premature baby was born to a G4P4 mother with the gestation age of 30 weeks. His birth weight was 2000 gm. He was noted to be covered with a thick, armor-like skin which is split by deep fissures and makes the feature of Ectropion and eclabium. His nose was flattened, only the nostrils were visible, and the external ears were underdeveloped. The hands and feet appeared to be swollen and crumpled. The genital organ was covered with thick fissured skin and it was impossible to distinguish sex by external appearance. Three days after delivery, the patient died of respiratory distress. He was found normal through general laboratory and chromosome study. However, dermatohistology showed hyperkeratosis, focal parakeratosis and hypogranulosis. Pathology showed PDA (patent ductus arteriosus), enlarged thymus and congestion of internal organs. Its etiology and pathogenesis somehow remain unknown. We hereby reported this harlequin fetus, the most severe type of lamellar ichthyosis, and discussed its incidence, pathogenesis, pathohistology, prognosis and the recent development in treatment.

Possible effects of transportation on mortality differentials in central Taiwan.

PIP: The author develops the hypothesis that transportation systems may affect mortality differentials in developing countries by facilitating or retarding accessibility to medical services. The hypothesis is tested using data for 39 townships in central Taiwan for the years 1980-1982. The results suggest that while transportation may be significant in explaining child mortality differentials, it does not significantly affect infant or neonatal mortality rates. (summary in CHI)^ieng

[Trends of phase-specific life expectancy in postwar Taiwan].

The decline in mortality in Taiwan since World War II is analyzed using life tables. "Special features of the research include (1) a phase-of-life-specific, rather than an age-specific, analysis of mortality, and (2) the use of measures based upon person-years of life in phase intervals, rather than survival rates or expectation of life at given ages. The empirical results suggest that the mortality decline can be described as a two-stage process: an initial stage of substantial improvement in life expectancy between 1950 and 1965, and a final stage of slow gain in life expectancy since 1965." Age and sex variations in mortality and differing rates of mortality decline are noted. Implications of increased longevity for economic and social programs are also considered. (summary in ENG)