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Biomedical subjects

H S Lin

Publications and source records attributed to H S Lin.

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

Follicular variant of papillary carcinoma: the diagnostic limitations of preoperative fine-needle aspiration and intraoperative frozen section evaluation.

OBJECTIVE: Fine-needle aspiration (FNA) and frozen section (FS) have been widely reported in the literature as having high sensitivity in the diagnosis of papillary carcinoma. With the increased recognition of the follicular variant of papillary thyroid carcinoma (FVPTC), several reports have pointed out the difficulty in diagnosing this variant of papillary carcinoma owing to its overlapping cytomorphological features with benign and malignant follicular lesions. We undertook this study to determine the sensitivity of FNA and FS in the diagnosis of FVPTC. METHODS: Retrospective review of patients who underwent thyroidectomy from June 1994 to June 1999. Of the 63 patients found with a final pathological diagnosis of papillary thyroid carcinoma, only 47 had an adequate FNA and FS and were included in the study. These patients were divided into two groups, the usual type (n = 23) and the follicular variant (n = 24) of papillary carcinoma. Sensitivities of FNA and FS for these two groups of papillary carcinoma were then determined. RESULTS: The sensitivity of the FNA was 25% and of the FS was 29% for the follicular variant of papillary thyroid carcinoma. This is in contrast to the sensitivity of FNA and FS for the usual papillary carcinoma, which were 74% and 87%, respectively. CONCLUSION: FNA and FS have low sensitivity in the diagnosis of the FVPTC. High degree of suspicion may increase the accuracy in the diagnosis of this variant of papillary carcinoma before or during surgery. However, the thyroid surgeon needs to realize that, like follicular carcinoma, FVPTC is often diagnosed only on final pathological examination.

Biopsy, Needle↗
PubMed2000

A cross-national examination of the determinants of self-assessed health.

Self-assessed health measures are often utilized in surveys of older adults, and these have been found to be powerful predictors of other health indicators and future health. However, there is still much that is puzzling about the measure. Few studies use comparative techniques to ascertain the determinants of self-assessed health across diverse settings. Using recent data from the Philippines, Taiwan, and Thailand, the current study tests whether determinants of self-assessed health are similar across samples and whether there are distinct country effects acting upon the association. Ordered probit models reveal that, on the one hand, the determinants of self-assessed health are relatively similar across the three countries, while, on the other, the overall probabilities of reporting favorable self-assessed health remain differentiated even when controlling for a broad series of determinants. The results suggest that cultural variation in the interpretation of health may be a factor and that more subtle measures should be included in future studies of this nature.

Aged↗
PubMed1999

Dibasic benzo[b]thiophene derivatives as a novel class of active site directed thrombin inhibitors: 2. Sidechain optimization and demonstration of in vivo efficacy.

Potent, subnanomolar thrombin inhibitors 4, 5, and 6 are developed through side chain optimization of novel, benzo[b]thiophene-based small organic entities 2 and 3 and through SAR additivity studies of the new structural elements identified. X-ray crystallographic studies of 4b-thrombin complex revealed a hydrophobic and an electrostatic interaction of these new elements with thrombin at the S2 and S3 binding sites. In vitro and in vivo pharmacological studies showed that 4, 5, and 6 are potent anticoagulants in human plasma with demonstrated antithrombotic efficacy in a rat model of thrombosis.

Animals↗
PubMed1999

Synthesis and in vitro biological activity of 4alpha-(2-propenyl)-5alpha-cholest-24-en-3alpha-ol: a 24,25-dehydro analog of the hypocholesterolemic agent 4alpha-(2-propenyl)-5alpha-cholestan-3alpha-ol.

4Alpha-(2-propenyl)-5alpha-cholestan-3alpha-ol (LY295427) was previously identified from a Chinese hamster ovary (CHO) cell-based low density lipoprotein receptor/luciferase (LDLR/Luc) assay to be a potent transcriptional activator of the LDL receptor promoter in the presence of 25-hydroxycholesterol. To investigate the effect of the 24,25-unsaturation in the D-ring side chain (desmosterol D-ring side chain) on antagonizing the repressing effect of 25-hydroxycholesterol, 4alpha-(2-propenyl)-5alpha-cholest-24-en-3alpha-ol (17), a 24,25-dehydro analog of LY295427, was thus synthesized from lithocholic acid via the formation of 3alpha-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-4alpha- (2-propenyl)-5alpha-cholan-24-al (15). Test results showed that 17 had an EC30 value of 2.6 microM, comparable to 2.9 microM of LY295427, in the CHO cell-based LDLR/Luc assay in the presence of 25-hydroxycholesterol. Apparently, the built-in 24,25-unsaturation in the D-ring side chain of 17 had added little effect to antagonizing the repressing effect of 25-hydroxycholesterol. In the [1-14C-acetate]cholesterol biosynthesis inhibition assay, 17 at 10 microg/ml (23 microM) has been shown to inhibit the cholesterol biosynthesis in CHO cells by 38% relative to the vehicle control; whereas LY295427 showed no inhibition in the same assay in our previous studies. In contrast to LY295427, the built-in 24,25-unsaturation in the D-ring side chain of 17 has conferred an inhibitory effect on cholesterol biosynthesis in CHO cells. In summary, the observed LDL receptor promoter activity of 17 is related to its ability to prevent 25-hydroxycholesterol from exerting the repressing effect via an undetermined mechanism and, in part, to inhibit the cholesterol biosynthesis.

Animals↗
PubMed1999

Synthesis and in vitro biological activity of 4alpha-(2-propenyl)-5alpha-cholest-24-en-3alpha,12 alpha-diol, a 12alpha-hydroxyl analog of 4alpha-(2-propenyl)-5alpha-cholest-24-en-3alpha-ol: the latter is a potent activator of the low-density lipoprotein receptor promoter.

4alpha-(2-Propenyl)-5alpha-cholest-24-en-3alpha-ol (3) was shown recently in a Chinese hamster ovary (CHO) cell-based low-density lipoprotein receptor/luciferase (LDLR/Luc) assay to be a potent transcriptional activator of the LDL receptor promoter in the presence of 25-hydroxycholesterol. Because of the involvement of 12alpha-hydroxylation in the metabolism of cholesterol, we are interested in investigating the effect of introducing a 12alpha-hydroxyl group to 3 on the transcriptional activity of the LDL receptor promoter. Thus 4alpha-(2-propenyl)-5alpha-cholest-24-en-3alpha,12a lpha-diol (14), a 12alpha-hydroxyl analog of 3, was synthesized from deoxycholic acid via the formation of 12alpha-[[(tertbutyl)dimethylsilyl]oxy]-4alpha-( 2-propenyl)-5alpha-cholest-24-en-3-one (11). Test results show that 14 is inactive at concentrations of up to 20 microg/ml, compared to 3 with an EC30 value of 2.6 microM, in the CHO cell-based LDLR/Luc assay. Apparently introduction of a 12alpha-hydroxyl group abolishes the capability of 3alpha-sterol 14 to activate the transcription of the LDL receptor promoter. However, in the [1-14C-acetate]cholesterol biosynthesis inhibition assay in CHO cells, 14 at 10 microg/ml (23 microM) is shown to inhibit the cholesterol biosynthesis by 51% relative to the control cells. Our previous studies indicated that 3 showed a 38% inhibition, but 4alpha-(2-propenyl)-5alpha-cholestan-3alpha-ol (1) exhibited no inhibition in the same assay at 10 microg/ml. In summary the results indicate that, in addition to the 24,25-unsaturation, the 12alpha-hydroxyl group in 14 has also conferred an inhibitory effect on cholesterol biosynthesis in CHO cells; however, the inhibition of cholesterol biosynthesis by 14 does not lead to the transcriptional activation of the LDL receptor promoter.

Animals↗
PubMed1999

Stress, social relations, and old age mortality in Taiwan.

The research analyzed the relationships among stress, social relations, and mortality in a probability sample of 4,049 Taiwanese adults, aged 60 and over. The baseline survey was conducted in 1989 and the survival status of the respondents was ascertained during the subsequent 4 years. Death of a spouse or a child was found to increase the risk of dying directly and indirectly, whereas major financial difficulty during the past 5 years and current financial strain influenced mortality indirectly through their effects on self-rated health disability. In addition to their direct effect on mortality, martial status and work status lowered the probability of dying through decreased disability and subjective ill health. Finally, no buffering effects of social support were substantiated.

Adaptation, Psychological↗
PubMed1999

Intergenerational influence in Singapore and Taiwan: the role of the elderly in family decisions.

This research examines intergenerational decision-making in Singapore and Taiwan. The focus is on elderly individuals and the extent to which they report being involved in influencing important family matters. The data used in the analysis were collected in focus group interviews and household-level surveys of the elderly (defined as ages 60 and over) in Singapore and Taiwan. Both survey samples were national probability samples. Everything else being equal, the extent to which seniors are consulted in family decisions declines with age and failing health in both countries. Whether they live in rural or urban places within Taiwan is also significant, and depending upon the context, socioeconomic variables such as home-ownership, employment status, and education further help predict to what degree the elderly are consulted in family decisions.

Journal Article↗
PubMed1999

A comparison of correlates of cognitive functioning in older persons in Taiwan and the United States.

OBJECTIVES: This article compares patterns of association between cognitive functioning and a number of sociodemographic and health correlates among older persons in Taiwan and the United States. METHODS: The study uses data from the 1993 Survey of Health and Living Status of the Elderly in Taiwan and the 1993 Study of Asset and Health Dynamics Among the Oldest Old in the United States. Separate multivariate regression models are employed for each country to examine the effects of sociodemographic and health factors on cognitive functioning, and to examine the marginal impact of cognitive functioning on activities of daily living (ADL) and instrumental ADL (IADL) functioning. RESULTS: Results of the multivariate analyses show similar patterns of association across the two countries and replicate findings from previous studies. Increasing age, female gender, lower education, depression, and selected health conditions are associated with lower cognitive functioning. In addition, although a significant predictor of both ADL and IADL impairments, cognitive functioning is more powerful with respect to explaining IADL impairments. DISCUSSION: Study findings suggest that the cognitive measures are capturing similar dimensions in Taiwan and the United States, and that factors associated with cognitive functioning and its consequences with respect to physical functioning are similar in the two countries.

Activities of Daily Living↗
PubMed1999

Surgical management of thyroid masses: assessing the need for frozen section evaluation.

OBJECTIVE/HYPOTHESIS: To determine the need for intraoperative frozen section to guide the extent of thyroid surgery in the presence of an adequate preoperative fine-needle aspiration (FNA) finding. METHODS: Charts of patients who presented from 1995 to 1998 to the two senior authors were reviewed. A total of 82 patients were found who satisfied the inclusion criteria of having both an adequate FNA and frozen section. The extent of surgery was based on the frozen section finding for all the patients in this study. The authors looked at the number of cases in which the surgical management would be changed if the frozen section was not obtained and the surgical decision was based only on preoperative FNA and intraoperative findings. RESULTS: FNA revealed papillary carcinoma in 18 patients that was confirmed by intraoperative frozen section and final pathology. In the remaining 64 patients, the FNA diagnosis was either benign or suspicious. When routine frozen section was done, 61 of these 64 patients were found to have either benign pathology or pathological diagnosis that was deferred to permanent section. Only three patients were found to have malignancy on frozen section that was missed by FNA. Of these three patients, two had obvious findings of malignancy at the time of surgery. This leaves only one patient with carcinoma that was missed by FNA and intraoperative findings but detected by the intraoperative frozen section. CONCLUSION: Of the 82 patients in this study, only one extra case of malignancy would be missed by elimination of the routine use of intraoperative frozen section. The authors conclude that the routine use of intraoperative frozen section may be unnecessary. The use of an adequate preoperative FNA together with sound clinical judgment at time of surgery can adequately guide the extent of surgical resection.

Adult↗
PubMed1998

Synthesis of 4 alpha-(2-propenyl)-5,6-secocholestan-3 alpha-ol, a novel B-ring seco analog of the hypocholesterolemic agent 4 alpha-(2-propenyl)-5 alpha-cholestan-3 alpha-ol.

4 alpha-(2-Propenyl)-5 alpha-cholestan-3 alpha-ol (LY295427) was previously identified from a CHO cell-based assay to be a potent LDL receptor up-regulator and had demonstrated to be an effective agent in lowering plasma cholesterol levels in hypercholesterolemic hamsters. In order to investigate the effect of flexibility of the 3 alpha-hydroxy-bearing A-ring on the activity, 4 alpha-(2-propenyl)-5,6-secocholestan-3 alpha-ol (11), a B-ring seco analog of LY295427, is thus synthesized from cholest-4-en-3-one. Test results indicate that 11 is not active in the CHO cell-based LDL receptor/luciferase assay at concentrations up to 20 micrograms/mL. The result underlines the importance of maintaining the A-B-C-D ring rigidity of the 3 alpha-sterols in terms of binding to the putative oxysterol receptor.

Animals↗
PubMed1997

Relationship between endothelial cell turnover and permeability to horseradish peroxidase.

The quantitative relations between cell turnover (cell mitosis and death) and macromolecular leakage were studied at the level of individual endothelial cells (ECs) in the thoracic aortae of 32 adult male Sprague-Dawley rats. The experiments were performed on en face preparations of aortic specimens obtained 1, 3, 5 or 10 min after the intravenous administration of horseradish peroxidase (HRP). Mitotic ECs were identified by hematoxylin nuclear staining; dying or dead ECs containing cytoplasmic immunoglobulin G were detected by indirect immunocytochemistry and endothelial leakages to HRP were visualized by light microscopy. The number and size of HRP spots increased with time and the spots fused to form large brown areas in 10 min. Quantitative data on the contributions of EC mitosis and EC death to the transendothelial leakages of HRP were obtained in the same animals. Although mitotic ECs (0.01%) and dying ECs (0.1%) were infrequent in occurrence, the great majority (over 90%) of these ECs were associated with focal HRP uptake. These mitotic and dying ECs, however, accounted for only 17% of the total leakage sites indicating that significant leakage of the 4-5 nm HRP also occurs in normal ECs not morphologically identified as being in mitosis or death. The percentages of leaky spots attributable to mitosis or cell death were greater for the 6 nm albumin and the 22 nm low density lipoprotein (LDL) which probably cannot traverse the normal junctions and use the leaky junctions during cell turnover as the major pathway.

Animals↗
PubMed1996

Immunocytochemical demonstration of a lipid droplet-specific capsule in cultured Leydig cells of the golden hamsters.

In this report, we provide direct evidence for the presence of a lipid droplet-associated capsule in hamster steroidogenic Leydig cells by using a monoclonal antibody A2. Leydig cells are characterized by containing many lipid droplets and having 3 beta-hydroxysteroid dehydrogenase activity. Immunofluorescence staining with this antibody demonstrated a rim or capsule surrounding the lipid droplets in Leydig cells, a pattern not seen with anti-vimentin antibody. Immunogold labelling confirmed ultrastructurally that antibody binding was distributed on the lipid droplet surface. In order to investigate the possible function of the capsule, we examined the morphological changes induced in the capsule following stimulation with LH or dibutyryl cAMP; the fluorescent intensity of the capsule was seen to gradually decrease, accompanied by a decrease in number and size of lipid droplets, and the response to both reagents was time- and concentration-dependent. We thus conclude that hormonal stimulation resulting in the detachment of certain capsular proteins from the surface of lipid droplets is mediated via the cAMP signaling pathway and may allow cholesterol ester hydrolytic enzyme direct access to its substrate in the lipid droplet.

Animals↗
PubMed1996

Prognostic factors of primary aldosteronism.

BACKGROUND: Primary aldosteronism (PA) is a rare but potentially curable cause of hypertension. Between October 1982 and November 1994, 30 patients of PA received unilateral adrenalectomy with a long-term follow up (mean:60.3 months). Nineteen (63.3%) cases were cured (Group 1); 11(36.7%) cases were improved (Group 2). The purpose of this study was to determine prognostic factors after surgery in patients with PA. METHODS: A retrospective analysis was performed regarding age and sex of the patients, duration of hypertension, family history of hypertension, preoperative blood pressure, plasma aldosterone concentration (PAC), plasma renin activity (PRA) and efficacy of spironolactone on blood pressure between both groups. End-organs (including kidney, heart, retina and brain) involvement was evaluated and compared. Adrenalectomy and renal biopsy specimen for pathology were similarly evaluated. RESULTS: The duration of hypertension was longer in Group 2 than in Group 1 (8.18 +/- 4.94 vs 5.21 +/- 4.24 years). The efficacy of spironolactone on blood pressure (BP) was positive in 81.8% of Group 1 and 16.7% of Group 2. Adrenal cortical adenoma in 24 cases with a cure rate of 70.8% (17/24) and adrenal cortical macronodular hyperplasia in 6 cases with a cure rate of 33.3% (2/6) were noted. Group 2 had more end-organs involvement than Group 1. The severity of histopathological change of the renal biopsy was similar. CONCLUSIONS: This study suggests that preoperative response of blood pressure to spironolactone administration predicts the postoperative prognosis of hypertension in patient with PA. Long duration of hypertension and involvement of two or more end-organs were poor prognostic factors. Excellent results can be achieved by unilateral adrenalectomy in adrenal cortical adenoma and fair results, in adrenal cortical macronodular hyperplasia.

Adolescent↗
PubMed1996

[A study of multiple factors related to Enterobius vermicularis infection among pre-school children in Ta-Liao district of Kaohsiung County].

In order to study the factors related to Enterobius vermicularis infection among pre-school children in Ta-Liao District of Kaohsiung County, a questionnaire was designed to interview parents of preschool children selected by random sampling from 7 kindergartens in Ta-Liao District. Enterobius infections in the children were then examined by using two-consecutive-day adhesive cellophane paper perianal swabs. The effective sample numbered 555 children. Variables causing the infection among infected and non-infected children were analyzed by chi-square test and point-biserial correlation. The results indicated that there were significant relationship between infection and the follow items: having snacks; sucking fingers; size of house; ways of cleaning house; place of activities; parent's cognizing that anus is the polluted source of eggs; recognition of the cause-and-effect relationship between eating in the bedroom and being reinfected with Enterobius; recognition of preventing reinfection of Enterobius by taking a shower; and educational background of father. Through logistic regression analysis with backward selection, the authors constructed a predicting model which can predict the infection rate of E. vermicularis among pre-school children according to the habit of having snacks, the habit of sucking fingers, size of house, parent's recognizing that taking a shower can prevent people from reinfection, and the educational background of father.

Child, Preschool↗
PubMed1996

Adaptation: a new concept in radiation biology and oncology and its clinical relevance.

A new concept of adaptation and cross-resistance in radiation biology and oncology is introduced. It explains the apparent difference in the radiosensitivity of cells of the same type (both normal and tumor) that are located in different parts of the body. Oxygen tension, which varies considerably from one part of the human body to another, ranges from 20 mmHg to 159 mmHg (2.7-21%). When cells are adapted to live in areas with high physiologic oxygen tension (high normoxic) such as the epidermis and upper and lower airways, they develop better antioxidant mechanisms, which include free radical scavengers and DNA repair, than cells that live in lower physiologic oxygen tension (low normoxic). Because the mechanisms of cell-damaging effects of ionizing radiation are similar to those of oxygen, the cell that is resistant to oxygen toxicity also becomes resistant to ionizing radiation (and certain cancer chemotherapeutic agents). Based on this concept, it could be expected that some human tumors such as primary cutaneous malignant melanoma and lung cancers contain cells that are relatively resistant to ionizing radiation as a consequence of living in a high normoxic condition and the treatment of these tumors may require different strategies.

Adaptation, Physiological↗