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Biomedical subjects

Y C Hsu

Publications and source records attributed to Y C Hsu.

At least 37 records · Page 2Linked to original sources
PubMed1996

Isokinetic strength of the quadriceps and hamstrings and functional ability of anterior cruciate deficient knees in recreational athletes.

OBJECTIVE: To test the hypothesis that increasing the hamstrings and quadriceps (H:Q) isokinetic strength ratio will, in the short term, improve the functional ability of an anterior cruciate ligament (ACL) deficient knee. METHODS: The isokinetic muscular characteristics at a speed of 60 degrees s-1 and 180 degrees s-1 of 46 recreational athletes with an arthroscopically confirmed ACL tear were determined using the Cybex II+ isokinetic dynamometer. The variables tested included peak torque, endurance ratio, total work output, and explosive power. Functional ability was scored with the Cincinnati rating system, measuring the severity of pain and swelling, the degree of giving way, and the overall ability to walk, run, ascent and descent stairs, jump and twist. RESULTS: Among all muscular characteristics, the H:Q ratio at 180 degrees s-1 at 30 degrees of knee flexion was shown to have the highest correlation to the functional score (r = 0.6249, P < 0.001). All variables involving hamstring strength were shown to be significantly correlated to the functional ability score (P < 0.01), while none of the variables involving quadriceps strength showed significant correlation with the functional ability of the injured knee. CONCLUSIONS: The H:Q ratio is strongly correlated to the functional ability of ACL deficient knees in Chinese recreational athletes. It could be used as an additional measure to guide in the decision making process in the management of ACL deficient knees.

Adult↗
PubMed1995

Human neuronal pentraxin II (NPTX2): conservation, genomic structure, and chromosomal localization.

We have previously identified a novel rat neuronal member of the pentraxin family (neuronal pentraxin) that may mediate the uptake of synaptic material and the presynaptic snake venom toxin, taipoxin. Here we report human cDNA and genomic sequences of a second neuronal pentraxin. This pentraxin, which we propose to name neuronal pentraxin II (NPII; gene symbol NPTX2), shows 54% amino acid identity to rat neuronal pentraxin (NPI) with 69% identity over the carboxyl-terminal half of NPI and is 88% identical to a newly identified sperm acrosomal pentraxin p50/apexin. Northern blot analysis reveals that NPII message is present in brain, testis, pancreas, liver, heart, and skeletal muscle, so, unlike NPI, NPII is not exclusively localized to neurons. Like NPI, NPII has potential N-linked glycosylation sites. The human NPII gene is 11 kb in length, contains four introns, and is localized to chromosome 7q21.3-q22.1. These data demonstrate the existence of a family of pentraxin proteins that are expressed in the brain and other tissues and that may play important roles in the uptake of extracellular material.

Amino Acid Sequence↗
PubMed1995

Studies of cloning, chromosomal mapping, and embryonic expression of the mouse Rab geranylgeranyl transferase beta subunit.

The mouse Rab geranylgeranyl transferase beta subunit has been cloned from a mouse E8.5 embryonic cDNA library. Sequence comparison reveals 97.4% sequence identity at the amino acid level to the rat clone isolated from an adult rat brain cDNA library. This gene, given a gene symbol of Rabggtb, is mapped in the distal region of mouse chromosome 3. It is ubiquitously expressed in adult animals but displays an interesting pattern of expression during a specific time of embryonic development. The expression of this gene can be detected in the whole embryos during early embryonic stages and is specifically concentrated in the developing brain, heart, and liver between gestation stages of E11.5 and E13.5. In addition, the expression of this gene is induced by retinoic acid in a mouse embryonal carcinoma cell line, P19.

Animals↗
PubMed1994

Tyrosine residue 719 of the c-kit receptor is essential for binding of the P85 subunit of phosphatidylinositol (PI) 3-kinase and for c-kit-associated PI 3-kinase activity in COS-1 cells.

The receptor tyrosine kinase c-kit is thought to mediate its diverse effects on different cell lineages by association and activation of distinct second messenger systems. One of the immediate events after binding of the kit ligand to the receptor is its association with the 85-kDa subunit (p85) of the phosphatidylinositol (PI) 3-kinase and the activation of the enzyme. In the present study, we examined the association and activation of PI 3-kinase with mutant forms of the c-kit receptor transiently expressed in COS-1 cells. To define the binding site of p85 we substituted the putative tyrosine phosphorylation sites in the kinase insert region of the c-kit receptor by phenylalanine (YF702, YF719, YF728, and YF745, respectively). The results indicate that, upon stimulation of cells with kit ligand, 1) the wild-type c-kit protein was readily autophosphorylated and autophosphorylation was not diminished significantly with any of the mutant proteins; 2) p85 and PI 3-kinase activity associated with wild-type c-Kit protein as well as with the mutant proteins YF702, YF728, and YF745. Ligand-induced association of p85 and PI 3-kinase activity were abolished with the YF719 c-Kit protein, and this was not due to different levels of expression of p85 or c-kit; and 3) c-kit receptor-bound p85 was not phosphorylated on tyrosine residues. These results indicate that tyrosine 719 within the 719YMDM motif in the kinase insert plays an important role in binding of p85 and that its phosphorylation is a prerequisite for binding of p85 and the subsequent activation of PI 3-kinase.

Amino Acid Sequence↗
PubMed1994

The ligand of the c-kit receptor promotes oocyte growth.

Both genetic and descriptive studies have implicated the c-kit receptor and its ligand, KL, in the process of oocyte growth in the postnatal mouse ovary. In order to test the hypothesis that KL is an oocyte growth factor, we used an oocyte culture system to study its effects in vitro. Initial experiments established that both ovarian c-kit and KL are biologically active. An immune complex kinase assay demonstrated that ovarian c-kit, found primarily on oocytes, has autophosphorylation activity, and a bone marrow-derived mast cell coculture assay indicated that granulosa cells produce functional KL. The addition of 10 ng/ml KL to growing follicles cultured in collagen gels resulted in a 67% increase in the rate of oocyte growth, and a doubling of the rate was achieved at around 50 ng/ml. ACK2, a monoclonal antibody against c-kit, severely inhibited the growth of late fetal and neonatal oocytes in coculture with ovarian cells and had less effect on growing oocytes cultured in follicles from 10- to 11-day-old mice. Genistein, an inhibitor of tyrosine kinases, including c-kit, blocked oocyte growth and disrupted follicle morphology. In initial studies on the regulation of KL production in granulosa cells, we found that both dibutyryl cyclic AMP and growing oocytes were able to induce increased KL mRNA accumulation in granulosa cell monolayers as assessed by Northern analysis. These studies demonstrate that c-kit and KL are required for maintenance of oocyte growth in vitro.

Animals↗
PubMed1994

Congenital biliary tract dilatation in infancy and childhood--74 cases experience.

This report presented a twelve-year experience from 1981 to 1992. Seventy-four cases of congenital biliary tract dilatation were at diagnosed an age of 6 days to 16 years. Twenty-two cases were infants. There were 54 females and 20 males. The ratio of female to male was 2.7:1. The classic triad of abdominal pain, jaundice and a palpable mass was seen in eleven cases (14.9%). Most children suffered from abdominal pain (50/74), vomiting (45/74), anorexia (42/74) and jaundice (34/74). Prolonged jaundice was the main symptom in infancy (15/22). A long common pancreatico-biliary channel was seen in six cases (6/47); the bile amylase level was elevated in five cases (5/20), one patient had a complex union with obstructive jaundice. All these cases were diagnosed by preoperative sonography accurately (100%). According to the Todani's classification, type Ia was the most common (40/74), followed by type IV-A (25/74) and type Ic (8/74). Cholelithiasis (13/74), perforation (9/74), and atresia/stenosis of distal choledochus (8/74) were the most common associated conditions. Cyst excision with biliary tract reconstruction was performed in all cases. Reoperation was needed in ten cases. Two cases died postoperatively due to sepsis and cholangitis induced hepatic failure.

Adolescent↗
PubMed1991

Meconium-stained amniotic fluid: a risk factor for microbial invasion of the amniotic cavity.

The purpose of this study was to determine whether meconium-stained amniotic fluid is a marker for microbial invasion of the amniotic cavity. Amniocentesis was performed on 707 patients presenting with preterm labor and intact membranes. Meconium-stained amniotic fluid was present in 4.2% (30/707) of patients with preterm labor. The prevalence of positive amniotic fluid cultures was significantly higher in women with meconium-stained amniotic fluid than in women with clear fluid (33% [10/30] vs 11% [75/677]; p = 0.001; odds ratio = 4.01; 95% confidence interval = 1.6 to 9.4). Patients with meconium-stained amniotic fluid were also more likely to have failed tocolysis and delivered a preterm neonate more frequently than patients with clear fluid (83% [25/30] vs 38% (258/677); p = 0.0001; odds ratio = 8.1; 95% confidence interval = 2.9 to 24.4). We conclude that meconium-stained amniotic fluid is a risk factor for microbial invasion of the amniotic cavity and preterm delivery in women with preterm labor and intact membranes.

Amniotic Fluid↗
PubMed1991

Mild orotic aciduria and uricosuria in severe trauma victims.

Hypermetabolic responses with respect to pyrimidine and purine kinetics in trauma victims were investigated during the catabolic phase before and after nutritional support. Orotic acid and uric acid excretions were measured in 32 adult, severely traumatized, hypermetabolic, and highly catabolic patients while they were receiving fluids with no calories or nitrogen. Patients were then fed intravenously amino acids and glucose or glucose alone or fed enterally for 5-6 d. Daily excretions of orotic acid, uric acid, urea, nitrogen, and creatinine were monitored. Mild orotic aciduria and uricosuria with hypouricemia were the basal-trauma responses. The significant (P = 0.001, r = 0.70) positive correlation between orotic and uric acid excretion demonstrates the parallelism between pyrimidine and purine metabolism. Feeding for 5-6 d could decrease but not readily abolish the injury-induced metabolic changes in nitrogen, pyrimidine, and purine metabolism. Glucose infusion alone may be sufficient to counteract the metabolic effects of trauma in the early flow phase of injury.

Adult↗
PubMed1990

Preterm delivery: a risk factor for retained placenta.

The purpose of this study was to determine whether preterm delivery, with and without intraamniotic infection, is a risk factor for retained placenta. This complication occurred more frequently in women with preterm vaginal delivery than in women with term vaginal delivery (9.1% [21/231] vs 1.1% [6/561]; p less than 0.00001; odds ratio = 9.25). There was no significant difference in the prevalence of retained placenta between women with preterm labor and intact membranes and those with preterm premature rupture of membranes (8% [10/125] vs 10.4% [11/106]; p greater than or equal to 0.05). A positive amniotic fluid culture or clinical chorioamnionitis was not associated with a higher incidence of retained placenta. This study indicates that preterm delivery is associated with an increased risk of complications of the third stage of labor.

Adult↗
PubMed1990

Epidemiology of shoulder impingement in upper arm sports events.

An epidemiological survey was conducted to collect data relating to the prevalence and frequency of shoulder pain and other related problems among different athletic groups that demanded vigorous upper arm activities. A questionnaire was administered on site thus ensuring that the response rate was 100 percent. Analysis of results revealed that of the 372 respondents there were 242 male (65.1 percent) and 130 female subjects (34.9 percent), with seven (1.9 percent) above the age of 40, 119 (32 percent) between the ages of 25 and 40, and 246 (66.1 percent) below 25 years of age. A total of 163 athletes (43.8 percent) indicated that they had shoulder problems, 109 (29 percent) suffering pain. Diffuse pain was indicated by 20 respondents (5.4 percent), while localized pain during movement was reported in 89 (23.9 percent). The prevalence of shoulder pain ranked highest among volley ball players (N = 28) followed by swimmers (N = 22), while badminton, basketball and tennis participants were equally affected (N = 10).

Adult↗
PubMed1989

A rapid, automated micromethod for measuring free fatty acids in plasma/serum.

The investigation of mobilization and utilization of fat as fuel in human subjects requires the quantification of free fatty acids (FFA) in the circulating plasma. Methods in current use involve tedious extraction and titration, or enzymatic reaction with colorimetric or fluorometric detections. A rapid and reliable micro-technique is needed. We have adapted the manual enzymatic method of the Wako NEFAC kit to an automated rapid assay performed with a micro-centrifugal analyzer. This method depends upon the specific acylation of CoA by FFA, followed by oxidation and condensation to form a purple adduct measurable at 550 nm. The acylation step requires incubation at 37 degrees C for 10 min, a critical step for serum/plasma analysis. Only 4 microL of plasma is needed, and 20 tests can be performed in 20 min. The precision (CV) of sample analysis is within 2%. The results for the samples analyzed by this technique are within 4% (SEM 1%) of results by the manual method. Thus accurate results are achieved at reduced cost, time, and sample size.

Acylation↗
PubMed1988

Searching for coding sequences in the mammalian genome: the H-2K region of the mouse MHC is replete with genes expressed in embryos.

We have searched for expressed genes in 170 kb of cosmid cloned DNA from the H-2K region of the mouse MHC. This region is known to contain two genes, H-2K and K2. We identified unique/low copy sequences evenly spaced along the cloned DNA, and used these as probes to search for conserved sequences in Southern blots from a variety of mammalian species. The majority of the unique sequences were found to have homologues and most of these were associated with CpG non-methylated islands. Northern blot analysis and isolation of clones from 5.5 and 10.5-day embryo cDNA libraries showed five additional genes encoded in the H-2K region. Four of these are abundant in embryos; the fifth is exclusively expressed in lymphoid cells. Our data indicate a minimum of seven genes in 170 kb, an unexpectedly high gene density. These results differ from two recent studies where similar lengths of cloned DNA were examined for expressed genes, and only one, or a part of one gene was found. The combined data suggest that the spatial organization of genes in the mammalian genome may not be random.

Animals↗
PubMed1987

Phosphorylation of type-L pyruvate kinase in intact hepatocytes. Localisation of the phosphorylation site in response to both glucagon and the Ca2+-linked agonist phenylephrine.

Pyruvate kinase is one of the enzymes which can be phosphorylated by stimulation of the cell with either glucagon or Ca2+-linked hormones. Whether these two classes of hormones phosphorylate the same site on the enzyme is unclear. Our results demonstrate that isolation of [32P]phosphorylated type-L pyruvate kinase from glucagon-treated hepatocytes followed by aspartyl-prolyl cleavage yields a [32P]phosphorylated peptide of Mr 17,000. This fragment is also phosphorylated in response to the Ca2+-mediated agonist phenylephrine.

Adenylyl Cyclases↗
PubMed1983

Development of mouse embryos grown in human cord serum (HCS) in vitro.

Mouse embryos of the blastocyst stage (day 0 of culture) were cultured in human cord serum (HCS) for 8 days. Until day 7 in vitro, the embryos had developed to the 4-5 somite stage. Apart from the occurrence of some cell necroses in the embryonic ectoderm and vacuoles in the yolk sac entoderm and to a lesser degree even in the embryonic entoderm, the in vitro development of the embryos was indistinguishable from the in vivo development. However, between days 7 and 8 in vitro the embryonic development was heavily disturbed. The most pronounced disturbances were visible in the central nervous system (CNS) of the embryos. A great number of the neuroepithelial cells of the entire CNS were necrotic. Even mesodermal structures, mainly the axial structures in the posterior part of the embryos, were affected, leading to disorganization of somites and notochord in this region. Since in the presence of rat serum embryos develop normally between days 7 and 8 in vitro (Hsu 1981; Chen and Hsu 1982), it was stated that HCS lacks an embryonic growth and differentiation factor (EGDF-4) present in rat serum which regulates the development of the CNS and the organization of the axial structures between days 7 and 8 in vitro, i.e., during the 4-5 somite stage and the time of the turning of the embryos (8-12 somite stage).

Animals↗
PubMed1982

Development of mouse embryos in vitro: preimplantation to the limb bud stage.

Mouse embryos were grown successfully in vitro from the blastocyst stage to the limb bud stage. Mouse blastocysts grown in vitro for 10 days showed blood circulation in the yilk sac, forelimb buds, and the primordia of liver, pancreas, and lungs. These characteristics are indicative of a developmental stage equivalent to one-half of the total gestation period in utero. Improvements in culture conditions from days 7 to 9 have made it feasible to culture mouse blastocysts beyond the early somite stage.

Animals↗
PubMed1981

Carcinomas induced by cell lines cultivated from normal mouse placentas.

Cell lines have been established from placentas of various strains of mice by in vitro cultivation. The established lines appear to be trophoblast cells as judged from their production of gonadotropin-like substance and their production of gonadotropin-like substance and steroid hormones. The cell lines lack detectable H-2 antigen, Fc receptor sites, Thy 1 and antigen and surface immunoglobulin determinants. In addition, the cells are resistant to murine type-C RNA tumor virus infection. The resistance is due to a block of viral replication after the stages of viral adsorption and penetration. The cell lines induced carcinomas after injection into adult mice of original host strains. Usually at least 2 x 10(6) cells are required to induce tumors by i.p. or s.c. injection. Transplantation of the tumor cells to various strains of mice revealed that some strains accepted and some strains rejected the transplant. Genetic crossings between susceptible and resistant mouse strains indicate that susceptibility to transplantation of tumor is determined by a single pair of dominant autosomal genes.

Animals↗
PubMed1980

Monozygotic twin formation in mouse embryos in vitro.

Monozygotic twins developed from cultured murine blastocysts at the ratio of approximately 1:100. The locus at which the denuded blastocysts attached to the culture dish was usually a random section of their mural trophoblasts, in which case single egg cylinders developed unilaterally. However, in those few blastocysts attaching with their antipolar mural trophoblasts, the inner cell mass became subdivided into two parts because of restrictions imposed on its growth by the apically situated polar trophoblasts and the plastic substrate. Each subdivision apparently incorporated totipotent cells, resulting in the bilateral formation of two egg cylinders sharing the same ectoplacental cone.

Animals↗