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Biomedical subjects

C S Tang

Publications and source records attributed to C S Tang.

At least 73 records · Page 4Linked to original sources
PubMed1998

Effects of metallothionein on action potentials of anoxic and reoxygenated papillary muscles of guinea pigs.

AIM: To study anti-arrhythmic effects of metallothionein (MT). METHODS: Standard microelectrode technique was used to study the effects of MT on action potentials (AP) in anoxic and reoxygenated papillary muscles of guinea pigs. RESULTS: MT (0.02 mmol.L-1) had no effects on AP of the normal papillary muscles; when the muscles were exposed to ischemic solution without MT, there was a marked shortening of action potential duration (APD) at 20%, 50%, and 90% of repolarization (APD20, APD50, APD90) from 82 +/- 7 to 37 +/- 7, 131 +/- 35 to 63 +/- 11, and 167 +/- 12 to 100 +/- 19 ms, respectively, (P < 0.01); and an obvious reduction of resting potential (RP), action potential amplitude (APA), and the maximal upstroke velocity of phase 0 (Vmax) from -92 +/- 9 to -63 +/- 12 mV, 135 +/- 13 to 80 +/- 8 mV, and 286 +/- 55 to 164 +/- 42 V.s-1, respectively (P < 0.01). However, in the presence of MT, the AP parameters (RP, APA, and Vmax) changed from -63 +/- 2 to -82 +/- 1 mV, 80 +/- 8 to 104 +/- 25 mV, and 164 +/- 42 to 237 +/- 43 V.s-1, respectively, (P < 0.01), except that APD20, APD50, and APD90 shortened further from 37 +/- 7 to 12 +/- 3, 63 +/- 11 to 28 +/- 7, and 100 +/- 19 to 82 +/- 11 mV, respectively (P < 0.01). MT decreased the incidence of automaticity during reoxygenation from 91% to 33%. CONCLUSION: MT possesses a calcium regulatory property.

Action Potentials↗
PubMed1998

Inhibitory effect of trapidil on proliferation of cultured rat aortic smooth muscle cells induced by endothelin-1.

AIM: To study the effect of trapidil (Tra) on endothelin-1-induced proliferation of cultured rat aortic vascular smooth muscle cells (VSMC). METHODS: The [3H]TdR incorporation into DNA assay, the number of VSMC, and cell cycle distribution were measured. RESULTS: Pretreated with endothelin-1 100 nmol.L-1, cell number, [3H]TdR uptake, and cell mitogenic activity increased 134% +/- 23%, 210% +/- 70%, and 86% +/- 18%, respectively. This proliferation was inhibited by Tra 5, 50, 500 mumol.L-1. The inhibitory rates were 12%-48%, 35%-54% and 15%-47%, respectively. Tra did not influence the proliferation of VSMC without endothelin-1 pretreatment. CONCLUSION: Tra antagonized the proliferation of VSMC induced by endothelin-1.

Animals↗
PubMed1998

[Effect of Arg-Gly-Asp-Ser (RGDS) peptide on ADP-induced signal transduction of activated rat platelet].

The purpose of this work was to investigate the effect of Arg-Gly-Asp-Ser (RGDS) peptide on platelet aggregation, protein phosphorylation, protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) activity during platelet activation. Experiments were performed on ADP activated rat platelets in vivo. Results showed that 50 mumol/L ADP, in addition to inducing platelet aggregation, obviously enhanced not only PKC and MAPK activities but also 95 and 66 kD protein phosphorylation. When platelets and ADP were incubated together with 50, 100, 200 mumol/L RGDS peptide it was found that the latter markedly inhibited ADP activated platelet aggregation and activation of PKC and MAPK, both in a concentration-dependently manner. RGDS peptide also inhibited 95 and 66 kD protein phosphorylation concentration-dependently and went positively with its activation of PKC and MAPK. The above result suggested that the antithrombotic effect of RGDS peptide was probably mediated through its effect on intracellular signal transduction in the ADP activation of platelets.

Adenosine Diphosphate↗
PubMed1998

[Inhibition of signal transduction pathways of endothelin-1-induced proliferation of vascular smooth muscle cells by nitric oxide].

The signal transduction pathways of the inhibitory effect of nitric oxide (NO) on endothelin (ET)-induced proliferation of vascular smooth muscle cells (VSMCs) were studied. 3H-thymidine (TdR) incorporation, mitogen-activated protein kinase (MAPK) activity and protein kinase C (PKC) activity of cultured VSMCs of rabbits thoracic aorta were measured in the presence of either NO precursor L-arginine (L-Arg) or NO donor 3-morpholino sydnonimine-hydrochloride (SIN-1), or ET-1 alone or with L-Arg or SIN-1. The results show: (1) ET-1 (10(-8) mol/L) significantly increased VSMCs 3H-TdR incorporation (5 times, P < 0.01), MAPK activity (4 times, P < 0.01) and PKC activity (3 times, P < 0.01), as compared with control. L-Arg or SIN-1 alone was without effect on 3H-TdR incorporation, MAPK activity and PKC activity. (2) When ET-1 and L-Arg (2, 5, 10 mmol/L) were simultaneously administered, 3H-TdR incorporation and activity of both MAPK and PKC were all significantly decreased in comparison with the ET group. (3) When ET-1 + SIN-1 (5, 10, 50 mumol/L), the effects coincide with those of the ET-1 + L-Arg groups. These findings indicate that NO inhibition of the signal transduction pathways of the ET-1-induced proliferation of VSMCs may be mediated by the inhibition of ET-1-induced activation of both PKC and MAPK.

Animals↗
PubMed1998

Role of endogenous carbon monoxide in hypertension pathogenesis of rats.

The present study investigated the contribution of endogenous heme oxygenase (HO)/carbon monoxide (CO) system to hypertension pathogenesis of rats. Zinc deuteroporphyrin 2,4-bisglycol (ZnDPBG), an inhibitor of heme oxygenase (HO), was used to inhibit HO activity in vivo. It was found that the blood pressure of rats with HO inhibition was significantly elevated, and plasma levels of adrenaline, noradrenaline, endothelin, nitrate and nitrite were significantly increased. HO activity and HbCO formation within vascular smooth muscle tissues were significantly inhibited after administration of ZnDPBG. Furthermore, administration of exogenous CO into HO inhibiting rats led to MABP decrease, but injection of HO substrate, heme-L-lysinate, had no effect on HO inhibition-induced hypertension. In spontaneously hypertensive rats, injection of exogenous CO resulted in a significant decrease of MABP, and heme-L-lysinate had a similar effect with exogenous CO. These data show that HO/CO system has an anti-hypertension biological action, suggesting that endogenous CO plays an important role in hypertension pathogenesis.

6-Ketoprostaglandin F1 alpha↗
PubMed1998

[Changes of mitogen-activated protein kinase activity in cardiac tissues, Ang II and cardiac hypertrophy in spontaneously hypertensive rats].

Mitogen-activated protein kinases (MAPKs) are thought to be critical components in signal transduction pathways in regulation of cell growth and differentiation. The purpose of the present investigation is to study possible involvement of MAPKs in the progress of cardiac hypertrophy in spontaneously hypertensive rats (SHRs) and effects of age on Angiotensin II (Ang II), MAPK activity and cardiac hypertrophy. The animals were divided into three groups: 4 months old WKY rats (n = 8), 4 month old SHRs (n = 8) and 15 month old SHRs (n = 6). Ratio of heart to body weight was measured. Ang II was determined by RIA. MAPK activity in cardiac tissue was assayed by the "in-gel" myelin basic protein phosphorylation. The results show that in comparison with 4 month old WKY rats, Ang II in plasma and cardiac tissues were elevated (216.4%, P < 0.01; 101.2%, P < 0.01) in 4 months old SHRs, while the MAPK activity was increased 107.0% (P < 0.01) with a parallel cardiac hypertrophy (P < 0.01). In comparison with 4 month old SHRs, Ang II and MAPK activity in cardiac tissue of the 15 months old SHRs were decreased (31.3%, P < 0.01; 29.7%, P < 0.05) but the cardiac hypertrophy increased by 38.5% (P < 0.01). MAPK may be involved in the progress of cardiac hypetrophy in SHR and the increased MAPK activity may be partly induced by Ang II.

Angiotensin II↗
PubMed1998

Anesthesia for pediatric herniorrhaphy or hydrocelectomy: comparison of propofol/ketamine and thiopentone/halothane.

Total intravenous anesthesia has recently become available for ambulatory surgery. It has the advantages of decreased air contamination from volatile anesthetics and decreased exposure of operating room personnel to volatile anesthetics. The purpose of this study was to compare the anesthetic properties of propofol/ketamine (total intravenous) anesthesia and thiopentone/halothane (intravenous and gaseous) anesthesia for herniorrhaphy or hydrocelectomy in children. Sixty children aged 2 to 7 years scheduled for herniorrhaphy or hydrocelectomy were allocated to two groups. The propofol/ketamine group (group 1) received a loading dose of intravenous propofol 3 mg/kg followed by propofol infusion 200 micrograms/kg/minute; additional bolus doses of propofol 1 mg/kg were given as needed or the infusion dose was increased or decreased by 33 micrograms/kg/minute as needed. Ketamine 1 mg/kg was administered intravenously 2 to 3 minutes before herniorrhaphy or hydrocelectomy to reinforce the analgesic and anesthetic effects of propofol. The thiopentone/halothane group (group 2) received intravenous thiopentone 6 mg/kg followed by halothane with 40% oxygen using a mask. Group 2 patients maintained spontaneous breathing with intermittent assistance and group 1 patients maintained spontaneous natural airway breathing during anesthesia. The scores on the postoperative assessment scale were higher in group 2 patients, indicating poorer anesthesia recovery characteristics, but the differences were not significant. Pain on injection was more frequent in group 1 (12/32) than in group 2 (2/28). The incidence of vomiting in group 2 (6/28) was significantly higher than in group 1 (0/32). We conclude that propofol/ketamine allows patients to maintain spontaneous natural airway breathing during anesthesia, and its analgesic and anesthetic effects are comparable to those of thiopentone/halothane. Propofol/ketamine is appropriate for pediatric herniorrhaphy and hydrocelectomy. It can be recommended for pediatric ambulatory surgery.

Anesthesia↗
PubMed1998

Injection pain with propofol: the effectiveness of thiopentone on induction.

One hundred and twenty-seven children aged 3-6 years were allocated to four groups. All of them received venous cannulation on the dorsum of the hand. On induction, the group L1, L2 and L3 patients received propofol 3 mg/kg mixed with lignocaine 0.15 mg/kg, 0.3 mg/kg, 0.6 mg/kg, respectively. The group T patients received thiopentone 3 mg/kg, then propofol 1.5 mg/kg mixed with lignocaine 0.075 mg/kg. Pain on injection was categorized into two-assessment items (facial expression and limbs withdrawal). The facial expression category were subdivided into none, mild (knit of brows), moderate (grimace), and severe (crying). The withdrawal of limbs was categorized into none, mild (withdrawal of hand), moderate (withdrawal of fore-arm and arm), severe (withdrawal of arm and twisting of body). Patients were monitored using an electrocardiogram, pulse oximeter, autonomic noninvasive blood pressure measuring device and capnography. The patient characteristics did not differ significantly among the four groups. Pain on injection was significantly more frequent in the group L1 patients (81%) compared with the group T (27%) patients. Increasing lignocaine dose reduced the incidence of pain graded as "moderate" or "severe" though there was no significant difference. The incidences of excitatory effect on propofol injection were reduced with increasing lignocaine dose and prior administration of thiopentone but there were no obviously differences among groups. We concluded that thiopentone reduced injection pain on propofol and should be recommended.

Anesthetics, Intravenous↗
PubMed1998

Clinical study of failure in continuous spinal anesthesia with bupivacaine.

BACKGROUND: Continuous spinal anesthesia (CSA) has been considered to be better in temporal and dose flexibility, as well as hemodynamic stability than single dose spinal anesthesia. However, the failure of spinal anesthesia is not a rare experience for anesthesiologists. Here we present our experience in solving the problem and discuss the possible causes for the failure. METHODS: 236 cases were studied retrospectively from January to December in 1996. All were over 65 years old, ASA III, scheduled for transurethral procedures or orthopedic operation. CSA was performed with 0.2% bupivacaine. Failed CSA was confirmed by positive pin-prick test at T10 dermatome(umbilicus) 30 minutes after 20 mg bupivacaine was injected. For failed cases, 5 mL 1% lidocaine was injected intrathecally for rescue. The failure rate, sensory and motor blockade, success rate by changing to lidocaine and its dosage were recorded. RESULTS: Eleven of 236 cases (4.7%) were considered spinal failure since the initial 20 mg bupivacaine could not provide adequate T10 anesthesia in 30 minutes. Addition of 5 mL 1% lidocaine produced a profound sensory and motor blockade in 9 cases, while further lidocaine injection was required in two cases. The success rate by rescuing lidocaine was 100% with an average lidocaine consumption by 52.5 +/- 4.5 mg. DISCUSSION: Factors contributed to failure spinal anesthesia including failure of technique, errors of judgment, maldistribution and failure of local anesthetic itself. However, we thought that change of pH value of local anesthetic in CSF may play a great part in these failed CSAs. Despite the reasons for failure, we demonstrate that failure of continuous spinal anesthesia by 0.2% bupivacaine can be readily resolved by 1% lidocaine.

Aged↗
PubMed1998

SEM study on microvascular changes following implantation of bone morphogenetic protein combined with hydroxyapatite into experimental bone defects.

BMP-HAP complex was implanted into a bone defect in the femur of Wistar-strain rats, and animals were allowed to heal for one to 8 weeks prior to sacrifice. Similar bone defects without BMP-HAP complex served as controls. Osseous healing and microvascular changes, as revealed by plastic microcorrosion castings, were subsequently examined under a scanning electron microscope. One week after implantation, sproutings and congregate sinusoidal capillary plexuses and primary bone trabeculae (woven bone) were observed around and between the BMP-HAP complexes. Control specimens revealed a fine and immature sinusoidal capillary plexus arising from sproutings and elongations of pre-existing blood vessels, but bone formation was not observed. At two weeks, newly-formed trabeculae were observed around and on the surface of the HAPs, and a network of thick, newly-formed vessels was observed in intervening space. At three weeks, networks of newly-formed vessels were observed on the surface of the HAPs, and surrounding newly-formed trabeculae had become thickened. At four weeks, bone defects were filled, and HAP was completely embedded in new bone. At eight weeks, the HAP was fused with new bone, and the boundary between the HAP and new bone was unclear. In comparison with comparable surgically created control bone defects without implanted BMP-HAP complex, BMP apparently stimulates new vascularization. Further, implanted BMP-HAP apparently stimulates undifferentiated mesenchymal cells to differentiate into angioblasts and osteoblasts, or vice versa (dedifferentiation).

Animals↗
PubMed1997

Psychosexual adjustment following sterilization: a prospective study on Chinese women.

The present study aimed to identify significant predictors of Chinese women's psychosexual adjustment after sterilization. One hundred fifteen multiparous Chinese women, aged 25-51 years, were interviewed before and after elective laparoscopic or postpartum sterilization. Eight-seven women were also interviewed about their pshychosexual adjustment at 1 year after sterilization. Results showed that the fear of negative evaluation by others, family cohesion and adaptability, and preoperative psychological distress were robust predictors of adverse psychosexual outcome immediately and 1 year after sterilization. There was significant improvement in women's mental health following sterilization, and their sexual adjustment such as coital frequency and sexual satisfaction were not adversely affected at 1 year follow-up. Women with either elective or postpartum sterilization had similar adjustment throughout, except the latter group tended to experience more physical discomfort at 1 year follow-up. About 3.4% of the women experienced regret at 12 months after sterilization.

Adaptation, Psychological↗
PubMed1997

Assessment of sexual functioning for Chinese college students.

Participating in this study were 305 Chinese college students in Hong Kong. Objectives included (i) examination of the psychometric properties of the Chinese version of the Derogatis Sexual Functioning Inventory (DSFI), (ii) exploration of the associations among various domains of sexual functioning, and (iii) description of Chinese students' sexual behavior. The Chinese DSFI shows satisfactory internal consistency, except the Information, Drive, and Satisfaction subscales. In general, sex-related domains such as sexual information, experience, drive, attitudes, fantasy, and satisfaction were related to each other and to body image. Compared to their counterparts in the U.S., Chinese college students were relatively sexually inexperienced and conservative. Mean ages of students having their first sexual intercourse experience were 17.14 for males and 18.13 for females; 11% of the students had premarital sexual intercourse experience, and the mean frequencies were once weekly for males and once or twice per month for females. Compared to female students, twice as many males acknowledged masturbation (21.4 vs. 43.8%), 4.2-8.2% students had experienced oral-genital sexual stimulation and 0-1.2% anal sexual activities.

Adolescent↗
PubMed1997

Psychosocial correlates of substance use: comparing high school students with incarcerated offenders in Hong Kong.

Drug use prevalence data were obtained from 969 adolescents, high school students and imprisoned offenders who reported use of cough medicine, organic solvents, cannabis, heroin, tranquilizers, and narcotics over the past six months. Incarcerated youths, in particular girls, had higher prevalence rates than students. Drug use frequencies were associated with psychosocial variables such as disinhibition, peer drug use, susceptibility to peer pressure, attitudes, encouragement by peers, and perceived availability of drugs. The psychosocial process of the initiation and maintenance of substance use was specified as a path model that considered 1) personality and social environment as distal precursors and 2) a drug-use predisposition and perceived availability as proximal precursors of three kinds of outcome variables: drug use, the intention to try illicit drugs if they were legal, and adverse outcomes of drug use. It was found that the same structural equation model fit the data of both samples of offenders and students, however, with very different weights assigned to the paths.

Adolescent↗
PubMed1997

Stress appraisal and social support of Chinese mothers of adult children with mental retardation.

Thirty Chinese mothers of adult children with moderate to severe mental retardation were interviewed to explore the source and nature of their stress and social support. Results revealed child-related and parent-related stress specific to these mothers. The most common stressors were future planning and behavioral problems of the target offspring. Mothers received tangible, emotional, and informational support mainly from family members and training center staff. Some evidence was also found for the optimal-matching model of stress appraisal and social support. Regardless of the duration of stress, all forms of support were perceived as equally useful for uncontrollable stress, whereas tangible support was regarded as more useful than informational support for controllable stress.

Adult↗
PubMed1997

[L-arginine transport in cultured vascular smooth muscle cells of spontaneously hypertensive rats and effect of liposome on the transport].

The characteristics of L-arginine (L-Arg) transport in cultured aortic smooth muscle cells (SMC) of spontaneously hypertensive rat (SHR) and control WKY rats were studied and the effect of liposome as L-Arg carrier on the transport was investigated. The results showed that the L-Arg transport of SMC in SHR was obviously lower than that in WKY rats. Maximum transport velocity (Vmax) of high and low affinity in SHR were respectively 48% (P < 0.01) and 49% (P < 0.01) of WKY rat, while the michaelis constant (K(m)) showed no significant difference (P > 0.05). Increase of L-Arg transport induced by tumor necrosis factor-alpha (TNF alpha) in SMC of SHR was obviously lower than that in WKY rats (P < 0.01). The uptake of L-Arg increased 10 to 20 times in SMC when incubated with liposome encapsulated L-Arg (Liposome-L-Arg) than with free L-Arg. The transport velocity in SMC incubated with liposome-L-Arg showed no significant difference in SHR and WKY rats (P > 0.05). The transport of liposome-L-Arg in SMC was not affected by TNF alpha in both the types of rats. The above results indicate that there exists a functional disturbance in L-Arg transport in the SMC of SHR, but the L-Arg transport in SMC can be obviously enhanced when liposome is used as L-Arg carrier. Thus, it appears that liposome-L-Arg may have clinical perspective in the treatment of hypertension.

Animals↗
PubMed1997

[Changes of calcium transport in rat liver nuclei during sepsis].

Calcium transport changes in rat liver nuclei were observed on the model of early sepsis (9 h after operation of cecal ligation and puncture). Calcium content in hepatocytes and nuclei were significantly increased by 20% and 36% respectively (P < 0.05) during sepsis. The activity of Ca(2+)-ATPase in hepatocytic nuclei was increased by 94% (P < 0.01) and 45Ca2+ transport accelerated by 32% (P < 0.01). There was a positive correlation between nuclear 45Ca2+ transport and nuclear Ca(2+)-ATPase activity (r = 0.914, P < 0.01). Calmodulin stimulated the activity of nuclear Ca(2+)-ATPase and 45Ca2+ transport; while calmodulin inhibitor trifluoperazine exerted an opposite effect. The above results suggest that liver nuclear calcium transport is strengthened during early sepsis as a result of changes of Ca(2+)-ATPase activity.

Animals↗