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Biomedical subjects

H W Chen

Publications and source records attributed to H W Chen.

At least 91 records · Page 5Linked to original sources
PubMed1997

The AC/A ratio, age and presbyopia.

Previous reports concerning the effect of age on the AC/A ratio have been equivocal. Therefore, the present study investigated both the stimulus (AC/As) and response (AC/Ar) ratios using a subjective haploscope-optometer in a relatively large sample of subjects (n = 42) over a wide range of ages (22-65 years). The AC/As showed a small but significant decrease with age (approximately 0.04 delta/D/year). When the older subjects (> 45 years of age) were excluded, however, there was no systematic age effect. The AC/Ar exhibited a small but significant increase with age (approximately 0.08 delta/D/year) for subjects under 45 years of age. However, when the older pre-presbyopes and younger presbyopes (35-44 years of age) were excluded, there was no systematic age effect. In subjects 45 years of age and older, the AC/Ar could not be reliably assessed. This was attributed to physiological and instrumentation noise as a result of the minimal change in accommodative response. In the mid-aged subjects (35-44 years of age), the apparent increase in AC/Ar with age was speculated to be due to neural adaptation of the crosslink gain from the accommodative to the vergence system and/or slight intrusion into the upper non-linear response region of accommodation with the measurements. The finding of AC/Ar constancy with age when mid-aged pre-presbyopes and early presbyopes were excluded supports the non-linearity hypothesis, and thus there appears to be no real change in AC/Ar with increased age. The results support the Hess-Gullstrand theory of presbyopia.

Accommodation, Ocular↗
PubMed1997

Application of cryoablation in the management of prostate cancer.

BACKGROUND: Radical prostatectomy is the most common and effective therapy for localized prostate cancer. But in addition to its surgical complications, even highly selected series carry a positive margin rate of 35 to 50%. Radiotherapy is another alternative for prostate cancer, but following radiotherapy there have been high positive biopsies reported. Cryosurgery, defined as in situ freezing and hence, devitalization of neoplastic tissues, has currently raised the interest of urologists in the management of localized prostate cancer or failed radiotherapy. MATERIAL: Five patients underwent transperineal cryosurgery of prostate in Chang Gung Memorial Hospital. Among them, three cases were stage D, one stage B and another failed radiotherapy of stage C prostate cancer. All patients received hormone therapy too. RESULTS: PSA declined in 3 patients and biopsies showed intraductal neoplasia. All 5 patients suffered from urine incontinence and one persisted. No mortality has been reported. CONCLUSION: Cryoablation of the prostate is an alternative for treatment of prostate cancer.

Aged↗
PubMed1996

Molecular cloning and developmental expression of mouse p130, a member of the retinoblastoma gene family.

With sequence homology to the SV40 T antigen-binding domain of the retinoblastoma protein (Rb), p107 and p130 constitute two additional members of the Rb family. To explore the potential function of p130 in mouse development, we cloned the full-length mouse cDNA for p130 and characterized p130 mRNA expression in mice. The deduced mouse p130 protein sequence shares a higher degree of similarity with mouse p107 than with mouse Rb. In adult mice, p130 mRNA is found in all tissues examined. Levels of p130 mRNA vary among different adult tissues, with the highest level in testis. Within testis, p130 mRNA is found predominantly in Leydig cells. Additionally, p130 expression in testis correlates with sexual maturation, suggesting p130 is important for the development of testis and, in particular, Leydig cells. In situ hybridization shows that in post coitus day 12.5 and 14.5 mouse embryos, distribution of p130 mRNA is quite uniform with the exception of a few tissues. Little differences in mRNA levels of either p130 or p107 were found between normal and Rb-deficient embryos, suggesting that p130 and p107 are expressed independently of Rb. Our data are consistent with the hypothesis that p130 and p107 do not compensate for the loss of Rb and support the view that p130 is related to, yet distinct from, the RB gene.

Aging↗
PubMed1996

Glutathione and glutathione-related enzyme activities of male and female rat hepatocytes under various culture conditions.

The effect of culture medium on glutathione (GSH) dependent detoxification defence system of primary cultured hepatocyte from either male or female rats was studied. Intracellular reduced (GSH) and oxidized glutathione (GSSG), and six GSH-related enzyme activities, including GSH peroxidase (GSH Px), GSH reductase (GSH Rd), cytosolic GSH S-transferase (cGST), microsomal GSH S-transferase (mGST), gamma-glutamyl transpeptidase (GTP), and gamma-glutamylcysteine synthetase (GCS), were investigated during a 6-day culture. Media free of fetal bovine serum (FBS) and with 2.5 or 10% FBS were used. Whatever the medium, there was an initial decrease of intracellular GSH and GSSG, a threefold increase of GSH at day 3 and fourfold increase of GSSG at day 4, later decreasing to their original level at day 6. The activities of all six GSH-related enzymes of male and female hepatocytes remained relatively stable during the first 72h, then gradually decreased to 50-80% of initial activities. With the exception of cGST, time-course profiles of other enzyme activities were not significantly different among various media. In both sexes, higher cGST activity was maintained for cells cultured in the presence of FBS. Results of immunoblotting analysis of cytosolic GST isozymes indicate that the placental form of GST (Yp) was markedly increased after plating and the extent of increase of Yp was higher in the presence of FBS. Despite the culture medium, the level of GST isoform Ya was maintained steadily for 6 days, however, Yb was maintained during the first 3 days and then decreased. In terms of the gender difference, GSH Px and GTP activities of hepatocytes from females were significantly greater than of males over the entire culture period. Results indicate that FBS seems not to be absolutely essential in maintaining GSH level and most of the GSH-related enzyme activities in rat hepatocytes. Furthermore, GSH levels and GSH-related enzyme activities of hepatocytes from female rats were similar to those from male rats.

Aminoacyltransferases↗
PubMed1996

The detection of S-glutathionation of hepatic carbonic anhydrase III in rats treated with paraquat or diquat.

Protein S-glutathionation has been demonstrated to be one of the cellular responses under oxidative stress and may be involved in many cellular metabolisms. In this study, the effect of redox cycling bipyridylium compounds, paraquat and diquat, on this protein modification was investigated. Male Sprague-Dawley rats were administered i.p. either paraquat at 20 or 40 mg/kg body wt. or diquat at 85 or 170 mg/kg body wt., respectively. The liver was examined at different time points for taking the measurement of the S-glutathionation of carbonic anhydrase III (CA III), thiobarbituric acid-reactive substances (TBARS), vitamin E depletion, glutathione (GSH) and glutathione disulfide (GSSG) contents. The extent of S-glutathionation of CA III was chosen as a marker and was determined by a method combining isoelectric focusing analysis with immunoblotting. Those results indicated that paraquat and diquat significantly increased the generation of TBARS and showed a time-dependent response. The significant effect on vitamin E depletion was only obtained in rats treated with a high dose of diquat for 2 h. Hepatic cellular GSSG contents did not increase but tended to decrease all of the treatments. Although oxidative damage was actually generated in liver, based on the increase of TBARS generation and vitamin E depletion, no increase of CA III S-glutathionation was observed. We propose that the reason for this observation under this circumstance is probably due to the reversible characteristic of CA III S-glutathionation, which has been demonstrated in our previous study (Chai et al., 1991) Arch. Biochem. Biophys. 384, 270-278) and named as dethiolation.

Animals↗
PubMed1996

Regulatory effects of dietary n-3 and n-6 lipids on plasma and hepatic lipid levels, liver cell number and microsomal protein content in spontaneously hypertensive rats.

Weanling male spontaneously hypertensive rats were fed semipurified diets containing either corn or fish oil for 8 weeks. Rats fed on fish oil diet had significantly lower plasma triglyceride, total cholesterol and HDL-cholesterol levels than rats fed on corn oil diet (P < 0.05). Moreover, rats fed on fish oil diet had significantly lower liver total lipid and triglyceride concentrations than rats fed on corn oil diet (P < 0.05). Dietary lipids were reflected in plasma fatty acid composition. Rats fed on fish oil diet had significantly greater plasma eicosapentaenoate (EPA) and docosahexaenoate (DHA) (n-3 PUFAs) with an accompanying decrease in plasma linoleate (LA) and arachidonate (AA) (n-6 PUFAs), in comparison with the rats fed corn oil (P < 0.05). Those results would suggest that the n-3 PUFAs were incorporated into plasma lipids at the expense of the n-6 PUFAs. Rats fed on corn oil diet had significantly greater liver DNA content than rats fed on fish oil diet (P < 0.05), thereby implying that the n-3 PUFAs in fish oil had an inhibitory effect on liver cell proliferation. Furthermore, rats fed on fish oil diet had significantly greater hepatic microsomal protein content than rats fed on corn oil diet (P < 0.05), indicating that fish oil exerted a stimulatory effect on hepatic microsomal enzymes.

Animals↗
PubMed1996

Blood pressure-lowering effect of fish oil is independent of thromboxane A2 level in spontaneously hypertensive rats.

Whether the alterations in the synthesis of thromboxane A2 (TXA2) is the direct mechanism underlying the blood pressure-lowering effect of fish oil was investigated in this study. Six groups of 11 male spontaneously hypertensive rats were fed semipurified diets containing corn or fish oils and graded levels (50, 5000 or 15,000 ppm) of dietary vitamin E for 8 weeks. Plasma TXA2, assayed by RIA, was significantly greater in the corn oil group than in the fish oil group (P < 0.05). Compared to 50 ppm dietary vitamin E, 5000 and 15 000 ppm dietary vitamin E, respectively, significantly decreased plasma TXA2 (P < 0.05). Systolic, mean or diastolic blood pressure, evaluated by the tail cuff method, were significantly higher in the corn oil group than in the fish oil group (P < 0.05). However, vitamin E had no effect on blood pressure. No relationship between TXA2 and blood pressure was found. Experimental results indicated that the alterations in the synthesis of TXA2 were not the direct antihypertensive effect of fish oil.

Animals↗
PubMed1996

Plasma vitamins A and E and red blood cell fatty acid profile in newborns and their mothers.

OBJECTIVE: In this work, we have measured the plasma vitamins A and E and red blood cell fatty acid profile in newborns and their mothers and have determined whether there are any relationships between maternal blood and cord blood for the nutrients measured. SETTING: The study was performed at the Chung Shan Memorial Hospital, Taichung, Taiwan. SUBJECTS: Twenty-nine pairs of mothers and their term infants. INTERVENTIONS: Maternal venous blood was collected in the first trimester and at delivery, and cord blood was collected at delivery. Plasma vitamin A and E levels were determined by high performance liquid chromatography and red blood cell fatty acid profile was estimated by gas chromatography. RESULTS: Mothers had significantly greater plasma vitamin A and E levels and vitamin E/total lipid than their term neonates did (P < 0.05). Maternal plasma vitamin E and vitamin E/total lipid were significantly greater in the first trimester than at delivery (P < 0.05). Red blood cell phospholipid oleate and linoleate were significantly greater in maternal red blood cell than in cord blood (P < 0.05), however, stearate and arachidonate were significantly greater in the cord blood than in the maternal blood (P < 0.05). Maternal vitamin E, vitamin E/total lipid, palmitate, linoleate, arachidonate and docosahexaenoate were found positively correlated to those in their neonates (P < 0.05). CONCLUSIONS: The results suggest that there is a relationship between maternal blood and cord blood for some nutrients. Therefore, the nutritional status of mothers may affect the nutritional outcome of their neonates.

Adult↗
PubMed1995

Lith1, a major gene affecting cholesterol gallstone formation among inbred strains of mice.

The prevalence of cholesterol gallstones differs among inbred strains of mice fed a diet containing 15% (wt/wt) dairy fat, 1% (wt/wt) cholesterol, and 0.5% (wt/wt) cholic acid. Strains C57L, SWR, and A were notable for a high prevalence of cholelithiasis; strains C57BL/6, C3H, and SJL had an intermediate prevalence; and strains SM, AKR, and DBA/2 exhibited no cholelithiasis after consuming the diet for 18 weeks. Genetic analysis of the difference in gallstone prevalence rates between strains AKR and C57L was carried out by using the AKXL recombinant inbred strain set and (AKR x C57L)F1 x AKR backcross mice. Susceptibility to gallstone formation was found to be a dominant trait determined by at least two genes. A major gene, named Lith1, mapped to mouse chromosome 2. When examined after 6 weeks on the lithogenic diet, the activity of hepatic 3-hydroxy-3-methylglutaryl-CoA reductase (EC 1.1.1.88) was downregulated as expected in the gallstone-resistant strains, AKR and SJL, but this enzyme failed to downregulate in C57L and SWR, the gallstone-susceptible strains. This suggests that regulation of the rate-limiting enzyme in cholesterol biosynthesis may be pivotal in determining the occurrence and severity of cholesterol hypersecretion and hence lithogenicity of gallbladder bile. These studies indicate that genetic factors are critical in determining gallstone formation and that the genetic resources of the mouse model may permit these factors to be identified.

Animals↗
PubMed1995

Effects of vitamin E deficiency and dietary linoleate on serum thromboxane synthesis in male sprague-dawley rats.

The aim of the present study was to examine whether vitamin E deficiency and dietary linoleate had additive or synergistic effects on serum thromboxane (TX) status and therefore on thrombogenesis. Eight groups of five male weaning Sprague-Dawley rats were fed semipurified diets containing 3.5 or 18.4% of energy from linoleate (en% linoleate) and 0, 100, 5000, 15,000 ppm vitamin E for 8 weeks. Rats fed no vitamin E had the lowest serum vitamin E while rats fed 15,000 ppm vitamin E had the highest serum vitamin E (p < 0.05). Serum 18:2, n-6 (linoleic acid; LA) and 20:4, n-6 (arachidonic acid; AA) were significantly greater in the 18.4 en% linoleate group than in the 3.5 en% linoleate group (p < 0.05). Serum TXA2, measured as its stable metabolite TXB2, was significantly greater in the vitamin E-deficient rats than in the vitamin E-adequate and vitamin E-supplemented rats (p < 0.05). Serum lipid peroxidation, measured as thiobarbituric acid reactive substances (TBARS), was significantly greater in the 0 and 100 ppm vitamin E groups than in the 5000 and 15,000 ppm vitamin E groups (p < 0.05). No interaction between dietary linoleate and vitamin E deficiency on serum TX status was found. However, it seemed that vitamin E deficiency had a more potent effect on TX synthesis than dietary linoleate. The result suggested that vitamin E deficiency may be prothrombogenic via its effect on TX synthesis.

Animals↗
PubMed1995

[Analysis of 117 cases of hypospadias--its location, operation and complication].

Hypospadias is a common congenital anomaly in male newborns. The incidence is about one in 300 live male births. In the U.S., about 6000 boys with hypospadias are born each year. For this study, we collected 117 recent (with the last 5 years) cases (88 fresh and 29 referred) who received an operation in our department. We calculated the hypospadias location and the complication rate with the desire of finding out the relationships between them. Our overall complication rate is 51.3% which is much higher than other recent studies and may be related to a different distribution of the hypospadias locations.

Adolescent↗
PubMed1995

[Comparison of UW solution and UR (a modified Collins) solution for renal preservation in renal transplantation].

For the storage of human transplanted organs, the benefit of "UW solution" has been proven especially in keeping a longer preservation time for the liver and pancrease; however, the value for kidney preservation was still debated. A total of 293 cases of renal transplantation were performed over 12 years in our hospital and 206 cases were cadaveric transplants. The latter ones were further divided into 3 groups, according to the immunosuppressive medication and preservation solution used. In the CsA treated groups, the ATN rates significantly decreased in those preserved with the UW solution than with the UR solution. Although the UW solution did not improve the graft survival in our series, it did save the cost for postoperative hemodialysis and shorten the hospital stay which made it cost effective.

Adenosine↗
PubMed1995

Effect of age on the interaction between the AC/A and CA/C ratios.

A number of previous studies have examined the effects of age and the development of presbyopia on either the accommodative convergence to accommodation (AC/A) or convergent accommodation to convergence (CA/C) ratios. However, changes in the interaction of these oculomotor crosslinks with increasing age have received relatively little attention, especially over a wide age distribution. Accordingly, the present study examined both crosslink ratios in 42 subjects ranging from 22 to 65 years of age. A dual haploscope-optometer was used to measure accommodation and vergence. The response AC/A ratio showed a small but significant positive correlation with age in those subjects under 45 years of age, while no significant correlation was observed between the stimulus AC/A ratio and age for all subjects. The CA/C ratio exhibited a significant negative correlation with age for all subjects. Furthermore, a trend was observed for lower CA/C findings to be associated with higher response AC/A ratios. However, the two ratios were inversely but not reciprocally related, with the mean difference between the CA/C ratio and the reciprocal of the response AC/A ratio being significantly different from zero. These age-related changes in the output of the oculomotor crosslinks provide further evidence of the continual oculomotor adaptation that occurs concurrent with the loss of accommodative responsivity.

Accommodation, Ocular↗
PubMed1995

Hepatic and adrenal changes in rabbits associated with hyperlipidemia caused by a semi-synthetic diet.

Several investigators have reported that feeding a semi-synthetic diet of casein and dextrose to New Zealand White (NZW) rabbits will increase total serum cholesterol concentration, principally through an increase in the beta-lipoprotein fractions, thereby creating a useful model for atherosclerosis research. Although there is evidence to suggest that the dextrose/casein diet alters low-density lipoprotein receptor and bile acid clearance of cholesterol, the underlying mechanism is not completely understood. The effects of the diet on the overall physiology of the rabbit have received little attention. In this study feeding a diet of casein and dextrose of male NZW rabbits for 4 weeks resulted in changes in the serum lipid concentrations. During that time the rabbits fed the dextrose/casein diet gained less weight than did control rabbits. In the test diet rabbits, liver aspartate and alanine transaminase activities were increased from baseline values of 27 +/- 2 U/L and 89 +/- 9 U/L respectively to 112 +/- 21 U/L and 281 +/- 34 U/L respectively, then returned to the high end of the reference range. Necropsy findings included hepatomegaly caused by vacuolar hepatopathy in 19 or 20 experimental rabbits; rabbits fed the control diet had no hepatic lesions. Ultrastructural analysis revealed that enlargement of the liver cells was due to glycogen deposition. Adrenal glands from animals fed the experimental diet had a minimal change in the size of the adrenocortical cells consisting of slight ballooning and rarefaction of the cytoplasm. In a second study the level of dietary fiber was doubled. This resulted in a three-fold increase in lipid concentrations, compared with the fivefold increase in the first study. The liver enzyme activities were increased to the same extent as in the first study. Histologic changes were comparable to those in the first study. The activity of hepatic cholesterol 7alpha-hydroxylase was 3.7 +/- 0.4 pmol/min/mg of protein, compared with the control value of 7.7 +/- 1.1 pmol/min/mg of protein (P < 0.05) in the second study. The improved rate of weight gain and the lesser increase in total serum cholesterol concentration in the second study with increased dietary fiber suggest that two separate activities may be involved. Although the level of dietary fiber may be related to weight gain and total serum cholesterol values, the relation to the decrease in liver transaminase activities in study 1 was probably coincidental. It appears that the dextrose/casein diet causes decreased activity of hepatic cholesterol 7alpha-hydroxylase, which could cause a decrease in the biliary excretion of cholesterol.

Adrenal Glands↗
PubMed1995

Characterization of a prolactin-synthesizing rat pituitary cell line immortalized by the temperature-sensitive mutant SV40.

A prolactin (PRL) synthesizing rat anterior pituitary (AP) cell line named tAP-CLC-2 was established by transformation with mutant temperature-sensitive A (tsA) simian virus 40 (SV40). The transformed cells were temperature-sensitive for morphology, cell propagation, and expression of phenotypic genes. Monolayer primary rat AP cells were transfected with a mutant SV40 (tsA 205) at 10 times the multiplicity of infection (MOI) at 34 degrees C. After cell clones formed, each clone was isolated and transferred to separate flask until sufficient cells were grown for freezing and characterization. At the permissive temperature (34 degrees C), these cells were spindle-shaped and grew rapidly like tumor cells. However, at the nonpermissive temperature (40 degrees C), the cells exhibited a rounded shape and ceased to propagate because the gene for maintenance of transformation was not expressed. Cell extracts from the cell line tAP-CLC-2 showed an inhibition curve parallel to that of normal rat pituitary cell extracts in a PRL radioimmunoassay (RIA). The gel filtration profile of immunoassayable PRL obtained from fast performance liquid chromatography (FPLC) showed that tAP-CLC-2 cell extract exhibited a PRL peak coincidental with primary rat pituitary cell extracts. Western blot showed that cell extracts from the tAP-CLC-2 cell line and from normal rat pituitary glands shared a similar, major immunoreactive PRL band. The tAP-CLC-2 cell line was responsive to estradiol (E 2; 10(-7) M), progesterone (10(-8) M), and gonadotropin-releasing hormone (GnRH; 10(-9) M) treatments. These hormonal treatments increased (p < 0.05) cell PRL content. Interestingly, treatment with a high dose (10(-7) M) of ovine luteinizing hormone (oLH) also increased (p < 0.05) PRL content in the cell line; a low dose (10(-9) M) of oLH did not. The cell line appeared to synthesize growth hormone (GH) as well. These results indicate this cell line has properties shared by primary AP cells and can provide a unique model for the study of the synthesis and gene regulation of PRL in vitro.

Animals↗
PubMed1995

Synthesis of Hsp72 induced by exercise in high temperature.

An investigation was undertaken involving the physiological effects of exercise in high temperature and its effect on the induction of heat shock proteins synthesis in peripheral lymphocytes and gastrocnemius. Male Long-Evans rats were employed. Environmental temperature was designed as three conditions: room temperature (26-27 degrees C), middle temperature (30-31 degrees C), and high temperature (36-37 degrees C). Rats were divided into one of three groups and exercised passively in an automatic round treadmill. Body temperature, biochemical changes were determined and the synthesis of heat shock protein 72 were analyzed by SDS-PAGE and immunochemical stain with monoclonal anti-Hsp72 antibody. Those results indicated that the body temperature elevated faster and higher in rats of high-temperature exercise group than those of a house temperature significantly (p < 0.05). Hsp72 could be detected only in lymphocytes from rats exercising in high temperature more than 60 minutes whose body temperatures were elevated above 41 degrees C. The induced Hsp72 appeared in lymphocytes 2 hours after exercise and reached maximally at 16-24 hours and then disappeared gradually. In gastrocnemius, Hsp72 could be detected even before the passive exercise, and its amount changed as in lymphocytes did in all three groups. No difference was found in blood sugar, hematocrit and CK among the three groups of rats. On the basis of above results, we can conclude that Hsp72 is synthesized in the muscle of intact rats, and exercise is a sufficient inducer. For lymphocytes, the presence of Hsp72 can be viewed as a heat stress in exercise.

Animals↗
PubMed1994

Effects of baicalein and esculetin on transduction signals and growth factors expression in T-lymphoid leukemia cells.

The possible mechanisms of antiproliferative effect of baicalein were studied in human T-lymphoid leukemia cells (CEM cells) and compared with those of esculetin. Baicalein, esculetin and related compounds, baicalein, wogonin, esculin and scoparone, inhibited CEM cell proliferation. Baicalein exhibited the greatest antiproliferative activity with an IC50 of 4.7 +/- 0.5 microM and the maximal suppression of 91.5 +/- 1.4% in CEM cells. The protein tyrosine kinase activity in the CEM cells was significantly reduced by baicalein (10(-6)-10(-4) M) and esculetin (10(-4) M). Baicalein exhibited a greater inhibitory activity on the protein tyrosine kinase than did esculetin (74.1 +/- 3.3% vs. 64.6 +/- 2.8% inhibition at 10(-4) M). On the other hand, the protein kinase C activity stimulated by phorbol-12-myristate 13-acetate was reduced by directly incubating with baicalein (10(-6)-10(-4) M) and esculetin (10(-4) M). However, the inhibitory activities on protein kinase C did not show a dose-dependency. The reverse transcription-polymerase chain reaction analysis of platelet-derived growth factor-A (PDGF-A) and transforming growth factor-beta 1 (TGF-beta 1) messenger RNA levels demonstrates that baicalein and esculetin reduced the PDGF-A mRNA level, but less affected the TGF-beta 1 mRNA. Baicalein exhibited the greater reduction on the expression of PDGF-A mRNA than did esculetin. It is suggested that baicalein and esculetin may affect cell proliferation by direct inhibition of growth-related signal, protein tyrosine kinase, as well as reduction of mRNA expression of growth factor, platelet-derived growth factor.

Cell Division↗