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Biomedical subjects

C C Hsieh

Publications and source records attributed to C C Hsieh.

At least 91 records · Page 5Linked to original sources
PubMed1998

Implementation of an oral and maxillofacial radiology image management and communication system.

OBJECTIVES: To implement an oral and maxillofacial radiology image management and communication system (OMFR IMACS) in the School of Dentistry, National Taiwan University. METHODS: An OMFR IMACS has been implemented over 3 years in three phases: (1) Establishment of an OMFR image processing laboratory for research and graduate student training; (2) Installation of network infrastructure and (3) Total system integration. RESULTS AND CONCLUSIONS: Intraoral, panoramic, cephalometric, and TMJ radiographs are directly processed with digital image acquisition devices or are converted into a digital format for viewing via UTP cable through FastEthernet in the eleven different divisions of the school. The system archives about 400 Mb of imaging data daily, representing 80% of the workload of the OMFR Division. The system is now used parallel to the conventional film-library system and has been integrated as part of the oral health service.

Humans↗
PubMed1998

Effects of age on the posttranscriptional regulation of CCAAT/enhancer binding protein alpha and CCAAT/enhancer binding protein beta isoform synthesis in control and LPS-treated livers.

The CCAAT/enhancer binding protein alpha (C/EBPalpha) and CCAAT/enhancer binding protein beta (C/EBPbeta) mRNAs are templates for the differential translation of several isoforms. Immunoblotting detects C/EBPalphas with molecular masses of 42, 38, 30, and 20 kDa and C/EBPbetas of 35, 20, and approximately 8.5 kDa. The DNA-binding activities and pool levels of p42(C/EBPalpha) and p30(C/EBPalpha) in control nuclear extracts decrease significantly whereas the binding activity and protein levels of the 20-kDa isoforms increase dramatically with LPS treatment. Our studies suggest that the LPS response involves alternative translational initiation at specific in-frame AUGs, producing specific C/EBPalpha and C/EBPbeta isoform patterns. We propose that alternative translational initiation occurs by a leaky ribosomal scanning mechanism. We find that nuclear extracts from normal aged mouse livers have decreased p42(C/EBPalpha) levels and binding activity, whereas those of p20(C/EBPalpha) and p20(C/EBPbeta) are increased. However, translation of 42-kDa C/EBPalpha is not down-regulated on polysomes, suggesting that aging may affect its nuclear translocation. Furthermore, recovery of the C/EBPalpha- and C/EBPbeta-binding activities and pool levels from an LPS challenge is delayed significantly in aged mouse livers. Thus, aged livers have altered steady-state levels of C/EBPalpha and C/EBPbeta isoforms. This result suggests that normal aging liver exhibits characteristics of chronic stress and a severe inability to recover from an inflammatory challenge.

Aging↗
PubMed1998

Serine protease activity is essential for thrombin-induced protein synthesis in cultured human dental pulp cells: modulation roles of prostaglandin E2.

Irritations and injuries to the dental pulp usually lead to different degrees of pulpal inflammation. To investigate the roles of thrombin and prostaglandins in the healing and inflammatory processes of dental pulp as well as their effects on pulpal protein synthesis, human dental pulp cell cultures were established and their protein production was measured with or without the presence of exogenous thrombin and prostaglandins. At concentrations of 1-25 U/ml, alpha-thrombin increased the protein synthesis to 1.4-2.3 fold over the vehicle control. On the contrary, 0.1 microg/ml of prostaglandin E1 (PGE1) suppressed protein synthesis by 60%. Prostaglandin E2 (PGE2) also inhibited protein synthesis with an IC50 of 0.4 microg/ml. The stimulatory effects of thrombin (10 U/ml) can be inhibited by antithrombin III (2 U/ml) (a natural thrombin inhibitor) with heparin (2 U/ml), PPACK (D-Phe-Pro-ArgCH2Cl) (20-50 microg/ml) (a serine protease inhibitor), and PGE2 (0.5-1.0 microg/ml). Moreover, TRAP (20-40 microg/ml), a thrombin receptor agonist peptide, also exerted a stimulatory effect (1.21-1.37 fold). In conclusion, thrombin-induced protein synthesis by pulp cells is dependent on proteolytic activity, but not on binding to receptors. Both PGE1 and PGE2 exert suppressive effects on protein synthesis, indicating that interactions between thrombin and prostaglandins are important in regulating the inflammation, repair and regeneration of pulp tissue following injury.

Adult↗
PubMed1998

Perinatal outcome of oligohydramnios without associated premature rupture of membranes and fetal anomalies.

To investigate the perinatal outcome of patients with oligohydramnios (amniotic fluid index < or = 5 cm), but without premature rupture of membranes and fetal congenital anomalies, data from 245 singleton pregnancies were analyzed and compared to those with normal amniotic fluid volumes (5 < amniotic fluid index < 24 cm, n=27,261). Significantly higher incidences of primiparity, pregnancy-induced hypertension, premature separation of placenta, past history of intrauterine fetal death, past history of preterm delivery, postterm pregnancy, and advanced maternal age were noted to be associated with the occurrence of oligohydramnios. Pregnancies complicated by a markedly diminished amniotic fluid volume assessed antenatally by ultrasound were significantly more frequently associated with adverse perinatal outcomes such as preterm delivery, low or very low birth weight, low Apgar scores, intrauterine fetal death, small-for-gestational-age newborns, meconium staining, cesarean delivery, neonatal intensive care, and neonatal death.

Cohort Studies↗
PubMed1998

Renal CCAAT/enhancer-binding proteins in experimental diabetes mellitus.

There is evidence that mediators of inflammation including components of the cytokine system are present in human and experimental diabetic kidney disease. CCAAT/enhancer-binding proteins (C/EBPs) represent a family of cytokine-inducible transcription factors. C/EBPs themselves regulate cytokine expression and also the expression of acute-phase reactants and connective tissue proteins. At least three C/EBP isoforms (alpha, beta, delta) are known. Upon stimulation with cytokines or bacterial lipopolysaccharide, the expression of the alpha isoform typically decreases, and the expression of the beta and/or delta isoforms increases. In view of the fact that components of the inflammatory response are present in diabetic kidney disease, there is a potential that the expression and activity of renal C/EBPs are altered in the diabetic state. In this study we sought to examine the status of C/EBP proteins in kidneys of rats with streptozotocin-induced diabetes mellitus. Diabetes was induced in 5 male Sprague-Dawley rats. Eight weight-matched non-diabetic rats were used as controls. Animals were sacrificed after 4 weeks, and the whole kidney nuclear protein was extracted. An electrophoretic mobility shift assay showed that DNA-binding activity was present in all five kidney nuclear extracts of the diabetic animals, but in only 2 out of 8 control samples (p < 0.05). A supershift assay showed that the DNA-bound protein complex consisted mainly of the C/EBPbeta isoform. Western analysis showed an increase of the C/EBPbeta protein in renal nuclear extracts of the diabetic animals compared to controls (p < 0.05). There was a decrease of the C/EBPalpha protein in the kidney nuclear extracts of the diabetic animals compared to controls (p < 0.05). We conclude that renal C/EBP dynamics are altered in experimental diabetes mellitus and that the patterns of C/EBP changes resemble those observed after cytokine or lipopolysaccharide stimulation.

Animals↗
PubMed1998

Areca nut extract inhibits the growth, attachment, and matrix protein synthesis of cultured human gingival fibroblasts.

Betel quid chewing is a popular oral habit in India, South Africa, and many Southeast Asian countries. The effects of areca nut (AN) extract on the growth, attachment, and protein synthesis of healthy human gingival fibroblasts (GF) were investigated to determine why betel quid (BQ) chewers have higher prevalence of periodontal disease than non-chewers. Twenty-four hour exposure of human GF to AN extract (> 200 microg/ml) in culture led to the formation of numerous intracellular vacuoles. As analyzed by modified MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide] assay, AN extract significantly suppressed the growth of GF over 5 days of incubation in a dose-dependent manner. At concentrations of 50 and 300 microg/ml, AN extract suppressed the growth of GF with 30% and 57% (P < 0.05), respectively. AN extract also significantly suppressed the synthesis of [3H]proline incorporation into trichloroacetic acid (TCA) precipitated proteins. At concentrations of 200, 400, and 600 microg/ml, AN extract suppressed the protein synthesis with 33%, 58%, and 63% of inhibition (P < 0.05), respectively. Preincubation of cells in a medium containing AN extract for 2 hours inhibits the subsequent attachment of cultured GF to type I collagen at the 50% inhibitory concentration (IC50) which is about 720 to 798 microg/ml. Considering the frequent consumption of BQ throughout the day, impairment of sequential fibroblast functions by BQ ingredients is a potential mechanism through which BQ chewing exert a deleterious effect to the gingival tissues.

Areca↗
PubMed1998

Childbearing and the risk of Hodgkin's disease.

The causes of Hodgkin's disease remain incompletely known, but a higher incidence in men than in women has prompted an interest in the role of female sex hormones and reproductive history. Available epidemiological data are, however, contradictory. We analyzed possible associations between parity, age at first birth, and the risk of developing Hodgkin's disease by a linkage between the Swedish Cancer Register and a nationwide Fertility Register. Among women born between 1925 and 1972, 917 cases with Hodgkin's disease and concomitant fertility information were identified. For each case patient, five age-matched controls were randomly selected among women in the Fertility Register. Conditional logistic regression was used to estimate odds ratios of Hodgkin's disease associated with a birth. We found a slightly and nonsignificantly reduced risk of Hodgkin's disease in ever-parous compared with nulliparous women. Among parous women, the number of children was unrelated to risk, whereas there was some evidence of an increased risk with late age at first birth in women under age 45 at diagnosis. No clear temporal relations between childbearing and subsequent risk were discernible in any parity or age group. Although uncontrolled confounding might have affected our results, they do not indicate that hormonal or immunological changes associated with childbearing play a role in the development of Hodgkin's disease.

Adult↗
PubMed1998

Effects of thrombin on the growth, protein synthesis, attachment, clustering and alkaline phosphatase activity of cultured human periodontal ligament fibroblasts.

Previous studies have indicated that thrombin can activate pulp cells, including fibroblasts. Because pulp cells and periodontal ligament (PDL) fibroblasts can express thrombin receptor mRNA, the specific aim of this study was to determine whether thrombin can activate the growth, attachment, protein synthesis, alkaline phosphatase activities and cellular clustering of cultured human PDL fibroblasts. Thrombin can stimulate the growth of PDL fibroblasts in a dose dependent manner (as analyzed by MTT assay). At concentrations of 5 and 10 U/ml, thrombin increased the cell numbers to 141% and 153% greater than that of the control after 5 days of incubation, respectively. Thrombin (5-20 U/ml) also stimulated the protein synthesis rate (assayed by [3H]proline incorporation) to 1.88-2.13 fold that of the control. However, pretreatment of PDL fibroblasts with thrombin (1-20 U/ml) could not promote the attachment of PDL fibroblasts to type I collagen and fibronectin. Moreover, thrombin could induce clustering of PDL fibroblasts within a concentration range of 5-20 U/ml. However, thrombin (1-20 U/ml) exerted neither stimulatory nor inhibitory effect on cellular alkaline phosphatase activities. In conclusion, it appears that the presence of thrombin seems to have effects on PDL fibroblasts in terms of cell growth, protein synthesis and cell clustering. This suggests that thrombin might be important in the early healing process of periodontium following periodontal surgery.

Alkaline Phosphatase↗
PubMed1997

Effect of parity and age at delivery on breast cancer risk in Slovenian women aged 25-54 years.

In 1988, a case-control study on breast cancer and oral contraceptives with 624 cases and 624 matched controls in the age range 25-54 years was undertaken in Slovenia. This analysis assesses the relationship between parity and breast cancer risk: the relative importance of age at first birth, age at subsequent births and total parity. We also evaluate whether a dual effect of an increased risk immediately after childbirth followed by a long-term benefit exists. Three logistic regression models were used. Age at first delivery is an important breast cancer risk factor: among parous women it was associated with a 5.3% increase/year in the odds of breast cancer. Multiparity was not shown to be an independent risk factor. Age at subsequent deliveries was associated with a 1% increase in risk for every 1 year increase of age at any birth, but this contribution to the risk was not significant. In the analysis stratified by parity the most important influence is with the age at first birth. We find no evidence of an effect on the odds of breast cancer associated with the age at the second, or later, births. We do find that there is an increased risk associated with the birth of the first child followed by a longer term protective effect. A post-menopausal woman has a reduced breast cancer risk compared with a pre-menopausal woman of the same age, adjusting for the same number of deliveries and ages at these deliveries.

Adult↗
PubMed1997

Cell cycle analysis and synchronization of pluripotent hematopoietic progenitor stem cells.

Hematopoietic stem cells purified from mouse bone marrow are quiescent with less than 2% of Lin- Hoechst(low)/Rhodamine(low) (Lin- Ho(low)/Rho(low)) and 10% to 15% of Lin-/Sca+ cells in S phase. These cells enter proliferative cycle and progress through G1 and into S phase in the presence of cytokines and 5% heat-inactivated fetal calf serum (HI-FCS). Cytokine-stimulated Lin- Ho(low)/Rho(low) cells took 36 to 40 hours to complete first division and only 12 hours to complete each of 5 subsequent divisions. These cells require 16 to 18 hours to transit through G0/G1 period and 28 to 30 hours to enter into mid-S phase during the first cycle. Up to 56% of Lin- Rho(low)/Ho(low) cells are high-proliferative potential (7 factor-responsive) colony-forming cells (HPP-CFC). At isolation, HPP-CFC are quiescent, but after 28 to 30 hours of culture, greater than 60% are in S phase. Isoleucine-deprivation of Lin- Ho(low)/Rho(low) cells in S phase of first cycle reversibly blocked them from entering into second cycle. After the release from isoleucine-block, these cells exhibited a G1 period of less than 2 hours and entered into mid-S phase by 12 hours. Thus, the duration of G1 phase of the cells in second cycle is 4 to 5 times shorter than that observed in their first cycle. Similar cell cycle kinetics are observed with Lin-/Sca+ population of bone marrow cells. Stem cell factor (SCF) alone, in the presence of HI-FCS, is as effective as a cocktail of 2 to 7 cytokines in inducing quiescent Lin-/Sca+ cells to enter into proliferative cycle. Aphidicolin treatment reversibly blocked cytokine-stimulated Lin-/Sca+ cells at G1/S boundary, allowing their tight synchrony as they progress through first S phase and enter into second G1. For these cells also, SCF alone is sufficient for their progression through S phase. These studies indicate a very short G1 phase for stem cells induced to proliferate and offer experimental approaches to synchronize murine hematopoietic stem cells.

Animals↗
PubMed1997

Epidemiologic aspects of gallbladder cancer: a case-control study of the SEARCH Program of the International Agency for Research on Cancer.

BACKGROUND: There are few previous epidemiologic studies of gallbladder cancer, a rare but nearly always lethal gastrointestinal cancer with a demonstrated greater frequency in adult women and older subjects of both sexes, and also in the members of populations throughout central and eastern Europe and certain racial groups such as native American Indians. Unfortunately, the prospects for the prevention of this form of cancer are poor. PURPOSE: Our purpose in conducting this study was to investigate possible new risk factors for gallbladder cancer and to strengthen our understanding of established causal agents that may be involved in this disease. METHODS: A large, collaborative, multicenter, case-control study of cancer of the gallbladder was conducted in five centers located in Australia (Adelaide), Canada (Montreal and Toronto), The Netherlands (Utrecht), and Poland (Opole) from January 1983 through July 1988. Case subjects with gallbladder cancer were accrued by the centers from hospital pathology records and from reports to regional cancer registries. Cancer diagnosis was confirmed by either biopsy, cholecystectomy, or at the time of autopsy. Control subjects were randomly assigned at each center from the population. The pooled analysis included 196 case subjects and 1515 control subjects (who did not report previous cholecystectomy). Ninety-eight percent of the subjects were white. Personal interviews of case subjects, control subjects, and surrogates (spouse or next of kin) were conducted by trained personnel. RESULTS: After adjusting for potential confounding factors (age, sex, center, type of interview, years of schooling, alcohol intake, and lifetime cigarette smoking), a history of gallbladder symptoms requiring medical attention (e.g., reduced bile secretion from the gallbladder into the small intestine due to obstructions of the common bile or cystic ducts) was the major risk factor associated with this form of cancer (odds ratio [OR] = 4.4; 95% confidence interval [CI] = 2.6-7.5). This association was present even in subjects who had their first gallbladder examination because of symptoms present more than 20 years earlier (OR = 6.2; 95% CI = 2.8-13.4). Other variables associated with gallbladder cancer risk included an elevated body mass index, high total energy intake, high carbohydrate intake (after adjustment for total energy intake), and chronic diarrhea. All of these risk factors have been previously associated with gallstone disease. CONCLUSIONS: These findings are consistent with a major role of gallstones, or risk factors for gallstones, in the cause of gallbladder cancer. Additional information on whether or not screening high-risk subjects for gallstones or gallbladder cancer is needed.

Adult↗
PubMed1997

The association between lactation and breast cancer in an international case-control study: a re-analysis by menopausal status.

In the large, hospital-based, international case-control study of breast cancer conducted by MacMahon and colleagues in the 1960s, no protective effect of lactation was observed. However, more recent reports have suggested that such an association may be limited to pre-menopausal women. Therefore, a re-analysis of the data from that original study was performed by menopausal status and with control for additional breast-cancer risk factors since identified. Overall, data from 4,671 parous pre-menopausal and 7,200 parous post-menopausal women were analyzed, from 7 different sites representing areas of high risk (Glamorgan, Wales; Boston, USA), moderate risk (Athens, Greece; Slovenia, ex-Yugoslavia; São Paolo, Brazil), and low risk (Tokyo, Japan; Taipei, Taiwan) of breast cancer. No significant effect of lactation was found for pre-menopausal or post-menopausal women from the high-, moderate-, or low-risk areas; the center-adjusted, combined odds ratio (OR) for having breast-fed was 1.05 (95% confidence interval, 0.86-1.29) among pre-menopausal and 1.04 (0.88-1.24) among post-menopausal women. Moreover, examination of cumulative duration of lactation did not support an inverse association between breast cancer and increased length of total breast-feeding. In conclusion, re-analysis of these data, by menopausal status and adjusting for age at first parity, age at menarche, age at menopause, body-mass index and years of schooling, did not reveal a protective effect of lactation or duration of lactation against breast-cancer occurrence among the pre-menopausal, parous women.

Adult↗
PubMed1997

Intrauterine environment and breast cancer risk in women: a population-based study.

BACKGROUND: The established risk factors for female breast cancer, including nulliparity, age at first birth, age at menarche, and age at menopause, do not adequately explain the occurrence pattern of this cancer. Therefore, additional factors need to be considered to advance our understanding of the causes of breast cancer. Evidence obtained from animals and humans indicates that the perinatal period may be particularly important. Our earlier studies, based on a subsample of the present investigation, suggested that factors thought to be positively associated with estrogen levels during pregnancy are positively associated with breast cancer risk. However, the associated confidence intervals (CIs) were generally wide, indicating considerable variability in the data. PURPOSE: We studied a large number of incident breast cancer case patients and evaluated several perinatal variables in relation to breast cancer risk. These variables included some not previously studied, such as gestational age and neonatal jaundice. We also investigated twin membership as a predictor variable and death from breast cancer, in addition to occurrence of breast cancer, as an alternative outcome variable. METHODS: Birth records for all deliveries at five different hospitals in Sweden during the period from 1874 through 1961 were used to define a large cohort of women. Incident case patients with breast cancer in this cohort were ascertained through the National Cancer Registry or the Uppsala Regional Cancer Registry from 1958 through 1994. In a case-control study nested in the cohort, we abstracted data from birth records on 1068 women with incident breast cancer and on 2727 control subjects individually matched to the case patients on date of birth. We modeled the data through conditional logistic regression. All P values were derived from two-sided statistical tests. RESULTS: We found a markedly reduced risk for breast cancer in women whose mothers had pregnancy toxemia (odds ratio [OR] = 0.41; 95% CI = 0.22-0.79) and an excess risk on women who had neonatal jaundice (OR = 2.16; 95% CI = 1.27-3.67) or who were born before 33 weeks of gestation (OR = 3.96; 95% CI = 1.45-10.81). Compared with the risk for breast cancer in the singleton, the risk for breast cancer in dizygotic twins was increased, although this increase was not statistically significant (OR = 1.72; 95% CI = 0.92-3.20). There was no evidence in these data for a statistically significant or substantial association of breast cancer risk with birth size indicators (i.e., weight and length at birth and placental weight). CONCLUSION AND IMPLICATIONS: Because pregnancy toxemia is associated with low levels of estrogens and neonatal jaundice, severe prematurity, and dizygotic twins with high levels of estrogens, our findings suggest that estrogens and other hormonal factors, known to influence breast cancer risk in the adult, may also play a critical role during the intrauterine period.

Breast Neoplasms↗
PubMed1997

In vitro cell density-dependent clonal growth of EGF-responsive murine neural progenitor cells under serum-free conditions.

Neural progenitor cell populations responsive to epidermal growth factor (EGF) have been shown to have proliferative potential and give rise to neurons, astrocytes, and oligodendrocytes. We have characterized EGF-responsive neural progenitor cells that give rise to bilineage neuronal/glial colonies (colony-forming unit neuron-glia; CFU-NeGl) and unilineage neuronal colonies (CFU-Ne). Clonality was confirmed utilizing mixtures of brain cells from Balb/c and ROSA26 (transgenic for beta-galactosidase) mice. With a few exceptions, colonies showed either all blue cells or all clear cells after staining with X-Gal. Clonal growth was analyzed after 10-11 days in relation to cell density by determining colony size and plating efficiency. Growth was density dependent (no growth below 10,000 cell/ml) and thus single cell cloning was not accomplished. An average plating efficiency of 4% was found for EGF-responsive neural cells derived from day 15-18 murine embryos when cultured at 12,500 to 200,000 cells/ml. Similar results were obtained with 1-day-old postnatal neural cells. When colonies were categorized by size, the relative number of colonies over 50 cells appeared to be maximum at 50,000 plated cells/ml. After 11 days in culture, 94, 96, and 78% of the colonies contained cells that expressed nestin, neurofilament, and GFAP, respectively. Double-label experiments revealed that > 62% of the colonies contained both GFAP and neurofilament expressing cells. These studies establish the existence of at least two populations of clonal neural progenitors: CFU-Ne and CFU-NeGl in fetal and postnatal murine brain.

Agar↗
PubMed1997

Long-term vegetarian diet and bone mineral density in postmenopausal Taiwanese women.

This study examined bone density among postmenopausal Buddhist nuns and female religious followers of Buddhism in southern Taiwan and related the measurements to subjects characteristics including age, body mass, physical activity, nutrient intake, and vegetarian practice. A total of 258 postmenopausal Taiwanese vegetarian women participated in the study. Lumbar spine and femoral neck bone mineral density (BMD) were measured using dual-photon absorptimetry. BMD measurements were analyzed first as quantitative outcomes in multiple regression analyses and next as indicators of osteopenia status in logistic regression analyses. Among the independent variables examined, age inversely and body mass index positively correlated with both the spine and femoral neck BMD measurements. They were also significant predictors of the osteopenia status. Energy intake from protein was a significant correlate of lumbar spine BMD only. Other nutrients, including calcium and energy intake from nonprotein sources, did not correlate significantly with the two bone density parameters. Long-term practitioners of vegan vegetarian were found to be at a higher risk of exceeding lumbar spine fracture threshold (adjusted odds ratio = 2.48, 95% confidence interval = 1.03-5.96) and of being classified as having osteopenia of the femoral neck (3.94, 1.21-12.82). Identification of effective nutrition supplements may be necessary to improve BMD levels and to reduce the risk of osteoporosis among long-term female vegetarians.

Adult↗