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Biomedical subjects

H Lo

Publications and source records attributed to H Lo.

At least 19 recordsLinked to original sources
PubMed2002

Optimal cut-off values for obesity: using simple anthropometric indices to predict cardiovascular risk factors in Taiwan.

BACKGROUND: The increased health risks associated with obesity have been found to occur in Asians at lower body mass indices (BMIs). To determine the optimal cut-off values for overweight or obesity in Taiwan, we examined the relationships between four anthropometric indices and cardiovascular risk factors. METHODS: The data were collected from four health-screening centers from 1998 to 2000 in Taiwan. Included were 55 563 subjects (26 359 men and 29 204 women, mean age=37.3+/-10.9 and 37.0+/-11.1 y, respectively). None had known major systemic diseases or were taking medication. Individual body weight, height, waist circumference (WC), and a series of tests related to cardiovascular risk (blood pressure, fasting plasma glucose, triglycerides, total cholesterol, low- and high-density lipoprotein cholesterol) were assessed and their relationships were examined. Receiver operating characteristic (ROC) analysis was used to find out the optimal cut-off values of various anthropometric indices to predict hypertension, diabetes mellitus and dyslipidemia. RESULTS: Of the four anthropometric indices we studied, waist-to-height ratio (WHtR) in women was found to have the largest areas under the ROC curve (women=0.755, 95% CI 0.748-0.763) relative to at least one risk factor (ie hypertension or diabetes or dyslipidemia). The optimal cut-off values for overweight or obesity from our study in men and women showed that BMIs of 23.6 and 22.1 kg/m(2), WCs of 80.5 and 71.5 cm, waist-to-hip ratios (WHpR) of 0.85 and 0.76, and WHtR of 0.48 and 0.45, respectively, may be more appropriate in Taiwan. CONCLUSIONS: WHtR may be a better indicator for screening overweight- or obesity-related CVD risk factors than the other three indexes (BMI, WC and WHpR) in Taiwan. Our study also supported the hypothesis that the cut-off values using BMI and WC to define obesity should be much lower in Taiwan than in Western countries.

Adult↗
PubMed2002

Four anthropometric indices and cardiovascular risk factors in Taiwan.

OBJECTIVE: To examine the relationships between four anthropometric measurements and cardiovascular risk factors in Taiwan. DESIGN: The data was collected from four nationwide health screen centers in Taiwan from 1998 to 1999. SUBJECTS: A total of 38 556 subjects: 18 280 men and 20 276 women, mean age=37.0+/-11.1 y. None had any known major systemic diseases or were currently on medication. MEASUREMENTS: Individual body weight, height, waist circumference (WC), and cardiovascular risk factors (blood pressure, fasting plasma glucose, triglycerides, total cholesterol level, low-density and high-density-lipoprotein cholesterol level) were assessed and their relationships were examined. RESULTS: In both sexes, with increasing body mass index (BMI), WC, WHpR (waist-to-hip ratio) and WHtR (waist-to-height ratio), there were significantly higher risks of hypertension, impaired fasting glucose, diabetes and dyslipidemia (P<0.001) in almost all age groups. In the age groups older than 65, however, the relationships were statistically inconsistent. CONCLUSIONS: In Taiwan, the four anthropometric indexes (BMI, WC, WHpR, WHtR) are closely related to cardiovascular risk factors.

Adult↗
PubMed2000

Comparison of a single half-dose, long-acting form of gonadotropin-releasing hormone analog (GnRH-a) and a short-acting form of GnRH-a for pituitary suppression in a controlled ovarian hyperstimulation program.

OBJECTIVE: To compare the effect of a single low-dose leuprolide acetate depot (LA depot) and leuprolide acetate (LA) on pituitary down-regulation in women undergoing controlled ovarian hyperstimulation (COH). DESIGN: Retrospective study. SETTING: An IVF unit of an academic medical center. PATIENT(S): Women who underwent COH and IVF-ET. INTERVENTION(S): Pituitary down-regulation with half-dose LA depot (1.88 mg sc, group 1) or LA (0.5 mg/d sc, group 2) was started on menstrual days 21-23. MAIN OUTCOME MEASURE(S): The concentrations of estradiol (E(2)), FSH, LH, gonadotropin dosages, the numbers of oocytes retrieved, oocytes fertilized and embryos transferred, and pregnancy rates of the two groups were compared. RESULT(S): A total of 289 patients in group 1 and 158 in group 2 were included. There were no statistically significant differences between the two groups in baseline concentrations of E(2) and FSH, concentrations of E(2), FSH, and LH during hCG administration, gonadotropin dosage, the number of oocytes retrieved, the number of oocytes fertilized and embryos transferred, and pregnancy rates. CONCLUSION(S): Single half-dose LA depot offers a useful alternative for pituitary suppression in ovarian stimulation for IVF.

Adult↗
PubMed2000

Cryopreservation of human spermatozoa within human or mouse empty zona pellucidae.

OBJECTIVE: To compare the empty zona pellucidae (ZP) of different species for use in the cryopreservation of spermatozoa. DESIGN: Prospective study. SETTING: An IVF unit of a medical center. PATIENT(S): Patients with azoospermia, oligoasthenozoospermia, or normal spermatozoa. INTERVENTION(S): Human and mouse ZP were prepared by evacuating the cytoplasm of oocytes or embryos. The evacuated ZP were injected with spermatozoa from patients with severe oligoasthenozoospermia and from healthy, fertile men. After the freezing and thawing procedure, the spermatozoa were aspirated outside the ZP. MAIN OUTCOME MEASURE(S): The number of spermatozoa per ZP, the number of motile sperm before freezing and after thawing, the number of sperm lost per ZP after freezing, and the sperm recovery rate were compared according to the different origins of the ZP and the sperm. RESULT(S): The number of spermatozoa, number of motile sperm before freezing and after thawing, number of sperm lost per ZP, and sperm recovery rate were comparable in all groups. The total mean number of motile sperm before freezing and after thawing, the mean number of nonmotile sperm after thawing, the mean number of sperm lost after thawing, and the sperm recovery rate were 14.5%, 11. 8%, 1.0%, 1.5%, and 82%, respectively. CONCLUSION(S): Zona pellucidae are an ideal vehicle for the cryopreservation of sperm collected by testicular sperm extraction or microsurgical epididymal sperm aspiration or from patients with severe oligoasthenozoospermia. There were no differences when human and mouse ZP were used for sperm storage.

Animals↗
PubMed1999

Use of ADCON in neurosurgery: preclinical review.

ADCON-L and ADCON-T/N are two bioabsorbable adhesion barrier gels designed to inhibit post-operative fibrosis around the dura and nerve structure. Two ADCON products were evaluated in animal models emulating their use in neurosurgery. In all studies ADCON-L and ADCON-T/N were safe and effective barriers to post-operative peridural and perineural fibrosis.

Animals↗
PubMed1999

A role for phospholipase C-gamma-mediated signaling in tumor cell invasion.

The invasive and metastatic transformation of cancers often results in death. However, the mechanisms that promote this transformation remain unclear. Two closely related receptors, the epidermal growth factor receptor (EGFR) and ErbB2, are overexpressed in a significant percentage of breast and prostate carcinomas, among others, with this up-regulated signaling correlating with tumor progression. Previous studies in our laboratory have demonstrated that an EGFR-phospholipase C (PLC)gamma-mediated motility-associated signaling pathway is rate-limiting for tumor cell invasion in vitro and in vivo in one model of prostate carcinoma. Therefore, we investigated whether this PLCgamma signaling pathway also was rate-limiting for invasion in other tumor cell lines and types and whether this EGFR activity is subsumed by the closely related ErbB2. We determined the effects of PLCgamma signal abrogation by pharmacological (U73122) and molecular (expression of the dominant-negative PLCz) means on the in vitro invasiveness of tumor cells. Inhibition of PLCgamma signaling concomitantly decreased invasiveness of de novo-occurring transgenic adenocarcinoma mouse prostate (TRAMP) lines and the human breast cancer cell lines MDA-468 and MDA-231; these lines present up-regulated EGFR signaling. Because the prostate and breast cancer lines usually present autocrine stimulatory loops involving EGFR, we also examined transgenic adenocarcinoma mouse prostate C1 and MDA-468 treated with the EGFR-specific kinase inhibitor PD153035 to determine whether invasiveness is dependent on EGFR signaling. PD153035 reduced invasiveness to levels similar to those seen with U73122, suggesting that the autocrine EGFR stimulatory loop is functioning to promote invasiveness. To determine whether this signaling pathway also promotes invasiveness of ErbB2-overexpressing tumors, we examined the human breast carcinoma line MDA-361; again, U73122 inhibition of PLCgamma decreased invasiveness. In all situations, the inhibition of PLCgamma signaling did not decrease mitogenic signaling. Thus, the motility-associated PLCgamma signaling pathway is a generalizable rate-limiting step for tumor cell progression.

Adenocarcinoma↗
PubMed1996

Poly(L-lactic acid) foams with cell seeding and controlled-release capacity.

A synthetic porous three-dimensional structure that can mimic the architecture of actual tissues, provide sustained release of nutrients or growth factors, and serve as a template for cell seeding would be an ideal substrate for tissue engineering. Poly(l-lactic acid) (PLLA) foams were fabricated for this purpose, based on the principle of phase separation from homogeneous naphthalene solutions. Complex shapes could be readily fabricated, and resulting foams had relatively uniform, open cells throughout the matrix. Densities and total pore-surface areas were in the range of 0.05-0.1 g/cm3 and 0.8-1.3 m2/g, respectively. The loss tangent of these foams ranged from 0.07 to 0.128, as measured by thermomechanical analysis. Naphthalene residue in the resulting foams went below 0.2 wt% after extensive vacuum sublimation. Feasibility of incorporating drugs or nutrients into such a highly porous structure was demonstrated by the dispersion of two model compounds, bromothymol blue (BTB) and sulforhodamine B (SD), in the matrix. Sustained release of BTB from the foam with a porosity as high as 87% was observed for more than 2 months. Alkaline phosphatase, as a model protein to be incorporated, lost approximately 30% of its bioactivity during the fabrication. As a cell-culture substrate, the PLLA foams performed as well as the flat PLLA surface in supporting the growth of rat osteosarcoma cells (ROS 17/2.8) and in maintaining their functions such as alkaline phosphatase activity and osteocalcin synthesis. UMR-106 cells cultured in the foam also expressed a higher degree of mineralization than those cultured on the flat PLLA substrate.

Alkaline Phosphatase↗
PubMed1996

Engineering of a sugar-derivatized porous network for hepatocyte culture.

Many tissue engineering applications require a scaffold or template conducive to cell attachment and maintenance of functions. It may also be advantageous in some cases for these scaffolds to have a controlled porous architecture to facilitate cellular or tissue ingrowth. In this study, we have engineered a porous carbohydrate-derivatized substrate for hepatocyte culture. Polystyrene foams, with pore sizes up to 100 microns, fabricated by phase separation from a homogeneous naphthalene solution, were derivatized with lactose and heparin, both of which are known to promote rat hepatocyte attachment and maintenance of its differentiated functions. Rat hepatocytes cultured on these derivatized foams exhibited a rounded cellular morphology with many microvilli evident on the surface of the cells. The hepatocytes showed an increase in albumin secretion for the first 3 days of culture in a defined, serum-free medium, and dropped back to initial levels by the end of 7 days. The production of cytochrome P450-dependent hydroxytestosterone metabolites were also measured. Two testosterone metabolites were maintained and five others were present but decreased over a culture period of 1 week. These carbohydrate-derivatized porous substrates may be useful for large-scale culture of hepatocytes, toxicology screening and for use in a liver assist device.

Animals↗
PubMed1992

Detection of point mutations of the phenylalanine hydroxylase gene and prenatal diagnosis of phenylketonuria.

The known mutant alleles of the human phenylalanine hydroxylase (PAN) gene were analyzed in 25 phenylketonuria (PKU) families from North China by using polymerase chain reaction and allele-specific oligonucleotide dot blot hybridization techniques. The results showed that the six mutations analyzed accounted for 62% of all PKU genes. The three most frequent mutations were R243Q, R413P and Y204C. Seven prenatal gene diagnoses were carried out in 6 PKU families and were confirmed after birth or by examination of aborted materials.

Base Sequence↗
PubMed1982

Biochemical and morphological properties of bovine erythrocyte membrane glycoproteins.

The major and minor sialoglycoproteins of the bovine erythrocyte have been solubilized and extensively purified. A comparison of composition revealed that the major glycoprotein had 77% carbohydrate and 23% peptide, and the minor one had 27% carbohydrate and 73% peptide. Molar ratios of sugars were related, however, the major glycoprotein had twice as much galactose and sialic acid as did the minor glycoprotein. Molecular weights, estimated from retardation coefficients of mobility in sodium dodecyl sulfate gel electrophoresis, were 55,000 for the major glycoprotein and 34,000 for the minor glycoprotein. The glycoproteins were studied by electron microscopy before and after delipidation and after ultracentrifugation. The major glycoprotein, prior to delipidation, formed large micelles. After delipidation, the major glycoprotein could not be visualized suggesting that it did not form aggregates in aqueous solution. The minor glycoprotein was visualized as rather uniform spherical aggregates (62 A average diameter) which tended to form short chains and small clumps. These characteristic aggregates were seen both before and after delipidation. After ultracentrifugation, fixation and sectioning both glycoproteins appeared to have formed microcrystalline arrays with average periodicity of 49 A.

Animals↗
PubMed1980

Purification and properties of NADPH:flavin oxidoreductase from Entamoeba histolytica.

Amebal NADPH:flavin oxidoreductase was purified to apparent homogeneity. Molecular weights of 40 000 and 38 000 were estimated by gel filtration and by sodium dodecyl sulfate polyacrylamide gel electrophoresis, respectively, indicating that the enzyme is composed of a single polypeptide chain. The enzyme does not contain firmly bound flavin. It exhibited 20-fold selectivity for NADPH over NADH. With the former donor it reduced riboflavin, galactoflavin, FMN, or FAD. Aerobically the reducing equivalents were passed from reduced flavin to oxygen to form hydrogen peroxide. Intact amebae do not produce peroxide when they respire. If the title enzyme functions to reduce flavin in the intact cells some electron carrier must intervene between reduced flavin and oxygen so that the final step produces water instead of peroxide.

Amino Acids↗
PubMed1978

Bordetella pertussis serotypes in Canada.

A study was done to determine the major antigenic factors of Bordetella pertussis strains isolated throughout Canada and whether these isolates have the same antigenic structure as the bacilli in the currently used vaccines. Testing for the major pertussis antigens, factors 1, 2 and 3, was conducted with 440 freshly isolated strains of B. pertussis received from seven canadian provinces between August 1976 and February 1978 and six batches of pertussis vaccine or immunizing agents containing pertussis vaccine. With the aid of specific antisera prepared in rabbits, the antigenic factors were detected by a slide agglutination technique. Almost all (98.9%) of the pertussis strains examined were serotype 1,3. All six batches of pertussis vaccine or immunizing agents containing pertussis vaccine proved to be rich in each of the three main pertussis agglutinogens.

Antigens, Bacterial↗
PubMed1976

Glucagon-mediated stimulation of (32P) orthophosphate and (14C) serine incorporation into phosphatidylserine in cardiac muscle slices.

Glucagon stimulated the incorporation of Na2H32PO4 and L-(14C)serine into phosphatidylserine in heart muscle slices. The increase above control was about 2-fold at ten minutes and 6-fold at thirty minutes for (32P) and 12-fold as early as three minutes for (14C)serine. Although a smaller, but significant, incorporation of (32P) into phosphatidylethanolamine was also observed, glucagon did not stimulate the incorporation of (14C)serine into phosphatidylethanolamine. Glucagon did not significantly augment the incorporation of either tracer into phosphatidylcholine, lysophosphatidylcholine, phosphatidylinositol, cardiolipin, phosphatidic acid, or sphingomyelin. Dibutyryl cyclic 3',5'-AMP did not increase the incorporation of (32P) or (14C)serine into phosphatidylserine. Since phosphatidylserine appears to serve a critical role in coupling the glucagon receptor to the catalytic moiety of adenylate cyclase, the data suggest that the hormone may initially increase the amount of its own coupler.

Animals↗