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Biomedical subjects

X Meng

Publications and source records attributed to X Meng.

At least 181 records · Page 10Linked to original sources
PubMed1997

[Expression of Fas and Fas ligand in liver tissue infected with hepatitis B virus].

Paraffin-embedded liver tissue from 60 biopsied or autopsied cases, including 20 cases each of acute mild hepatitis, chronic active hepatitis and active cirrhosis were studied with immunohistochemical double labelling technique by using polyclonal anti-Fas and anti-Fas ligand. The detection rates for Fas and Fas ligand were 76.7% (46/60) and 70.0% (42/60), respectively. Fas antigen was located in cytoplasm of hepatocytes. Fas ligand was expressed mainly in infiltrating lymphocytes in portal or periportal areas (34/42, 80.9%) and also in the cytoplasm of some hepatocytes (25/42, 59.5%). The distribution of Fas ligand-positive hepatocytes was similar to that of Fas-positive hepatocytes in liver tissue. The positive cells were scattered in the intralobular areas in acute mild hepatitis, but they were more commonly aggregated in periportal areas, especially near the edges of the piecemeal necrosis region or in infiltrating mononucleocytes in chronic active hepatitis and active cirrhosis, Double labelling studies showed that both Fas and Fas ligand might be expressed in the same or different hepatocytes of the same area. Our results suggest that Fas-Fas ligand system may play an important role in liver cell injury due to hepatitis B virus infection.

Acute Disease↗
PubMed1997

[The setting up of human serum calcitonin radioimmunoassay and its clinical application].

This study deals with the setting up of human serum calcitonin radioimmunoassay (hCT-RIA) using the high titer and specific antibody which was prepared by our own laboratory. The final dilution of the antibody titer was 1:1,200,000 when the binding rate of Bo/T was 30%. The antibody's affinity constant (Kd) was 2.25 x 10(11) L/M. No cross reaction was found between the antibody and the following eight different peptide hormones and proteins, viz.: TSH, T3, T4, ACTH, PTH, BGP, Insulin and Gastrin. The coefficients variation of intra and inter assay were 3.2% and 9.0%, respectively. The mean recovery rate of CT was 99.8%. The sensitivity of this assay was 9.4 pg/ml. The examination of this methodology showed that all its indices met the demands of RIA. There was no difference in the mean value of serum CT between the two sexes in 232 normal subjects, but the serum CT concentration in those aged of sixty and over of men and women, were much lower than those aged of fourty group. Mean CT concentration was low in the patients with primary osteoporosis, but were significantly higher in those suffering from medullary thyroid carcinoma, primary hyperparathyroidism crisis and chronic renal failure.

Adult↗
PubMed1997

[The frequencies of the vitamin D receptor gene alleles in adults of Han nationality in Beijing area].

Vitamin D receptor (VDR) gene is considered as one of candidate genes related to the genetic basis of bone and mineral metabolism. In order to determine VDR genotypes, we analysed the polymorphisms, or genotypes of Bsm I, Apa I, and Taq I restriction enzymes, by PCR technique in 223 unrelated healthy adults of Han nationality in Beijing area. Some of the VDR genotypes were also confirmed by Southern blotting analysis. We discovered that Chinese had high frequencies of b, a, T alleles, as high as 95%, 75%, and 95% respectively, which were different from those in Caucasians and Japanese, but similar to those in Koreans (P > 0.05). This difference gave us further insight into the different pathogeny of osteoporosis in various ethnics.

Adult↗
PubMed1997

[The association between vitamin D receptor gene polymorphisms, bone mineral density and osteocalcin in Chinese women].

OBJECTIVE: To investigate the correlations between vitamin D receptor (VDR) gene polymorphisms, and bone mineral density (BMD) as well as osteocalcin. METHODS: We used PCR-RFLP and Southern hybridization analysis to determine VDR genotypes in 202 Chinese women. BMD was measured by dual-energy X-ray absorptiometry (DEXA) and serum osteocalcin level was determined by radioimmunoassay. Analysis of covariance was used to test differences in mean BMDs across genotypes. RESULTS: We realized that VDR genotype frequencies in Chinese women were apparently different from those of Caucasians. In group of postmenopausal women, "bb" or "aa" genotype was related to lower BMD in Femoral Neck and Trochanter. No association was found between VDR genotypes and the serum osteocalcin level. CONCLUSION: There was some association between VDR genotypes and BMD in Chinese women. Its function in predicting osteoporosis still requires further study.

Adult↗
PubMed1997

[Separation and purefied of calf osteocalcin, set up radioimmunoassay for osteocalcin].

OBJECTIVE AND METHODS: We extracted and purified osteocalcin (BGP) from calf femur by gel filtration, FPLC and HPLC subsequently. The rabbits were immunized by this antigen and produced antibody. With this antibody (final 1: 35,000 dilution) we established RIA for BGP. This assay is stable and sensitive, the kd was 2.29 x 10(11). The intra assay variation was 2.1% and the inter assay variaton was 5.6%. It has no crossreaction with insulin, parathyroid hormone or calcitonin. RESULTS: The serum BGP values were detected in normal subjects and six kinds of bone metabolic diseases. In 81 normal subjects, the average serum BGP level was (5.3 +/- 1.5) ng/ml and in postmenopausal osteoporosis the serum BGP level [(6.2 +/- 1.9) ng/ml, n = 42] was higher than the normal (P < 0.05). The serum BGP levels were increased much in primary hyperparathyroidism [(12.8 +/- 7.0) ng/ml, n = 21, P < 0.001]. Increased values of BGP were also found in patients with chronic renal failure [(8.5 +/- 2.4) ng/ml, n = 18, P < 0.01] and Paget's disease [(6.7 +/- 2.2) ng/ml, n = 12, P < 0.05]. Decreased serum BGP values were found in Cushing syndrome [(2.9 +/- 0.9) ng/ml, n = 16, P < 0.001] and hypoparathyroidism [(3.4 +/- 1.1) ng/ml, n = 42, P < 0.001]. This result showed that in diseases with high bone turnover, the serum BGP levels were increased and in diseases with low bone turnover, the serum BGP levels were decreased. CONCLUSION: The data suggest that serum BGP is a sensitive marker for bone turnover. It is very improtant in studying bone metabolic diseases.

Adult↗
PubMed1997

[Gama hydroxybutyrate sodium (gama-OH)-diazepam combined anaesthesia for cleft palate repair in children below 3 years old].

UNLABELLED: To investigate the effect of Gama-OH-Diazepam combined anaesthesia for cleft palate repair in children below 3 years old. METHODS: Heart rates were measured in 120 children at induction, at 5 minutes after endotrocheal intubation, at finishing of operation, and at 5 minutes after extubation. In addition, changes of SpO2 was randomly detected in 10 children. RESULTS: Heart rate decreased after intubation, increased when operation was completed and decreased again after extubation. SpO2 of all stages were in the normal range. CONCLUSIONS: This method of anaesthesia is suitable for cleft palate repair in children below 3 years old, with the advantages of little effect on the children's circulatory and respiratory systems, and being easy to perform and control.

Anesthesia, Intravenous↗
PubMed1997

[The hepatic ischemia/reperfusion injury in cirrhotic rats].

We assessed ischemia/reperfusion injury in carbon tetrachloride induced cirrhotic liver as compared to normal liver in the rats. Hepatic vein nitric oxide (NO) level was measured by method of luminol chemiluminensence, and portal vein endotoxin level by limulus lysate with chyomogenic substract. In cirrhotic liver, instead of diminishing the hepatic vein NO level increased significantly after ischemia and remained high till 5 hrs postreperfusion. The portal vein endotoxin level was also increased but to a higher level than that of normal liver. In cirrhotic liver, ischemia/reperfusion injury is aggrevated as evidenced by higher level of endotoxin, increased generation of NO.

Animals↗
PubMed1997

[Antioxidative effect of constituents of herba Epimedii (ESPS)].

Herba Epimedii is a traditional Yang invigorating Chinese herb widely used in clinic. The experimental results have shown that ESPS obviously increases superoxide dismutase(SOD) activity of red cells and liver in aged mice and rats, and increases glutathione peroxidase(GSH-Px) activity of red cells in aged mice. On the other hand, ESPS obviously helps to reduce the content of serum and liver lipoperoxide(LPO) in aged mice and rats, as well as the content of lipofuscin(LF) in cardiac muscle of aged mice. The results suggest that being helpful in increasing SOD and GSH-Px activities and inhibiting the formation of LPO and LF, ESPS may be a good antiageing agent.

Aging↗
PubMed1997

[Evaluation of oral glucose tolerance test in the assessment of reserved function of liver for patients with hepatocellular carcinoma].

The aim of this study was to evaluate oral glucose tolerance test(OGTT)in the assessment of reserved function of liver for predicting the tolerability of patients to hepatectomy and hence provided a criteria for selecting the candidates for undergoing hepatectomy, since the majority of hepatocellular carcinoma (HCC) patients were associated with posthepatitis cirrhosis. The preoperative and postoperative OGTT and liver biopsy for pathological investigation were carried out in 62 cases of hepatecomized patients and 49 cases of unresected patients for comparison. The results revealed that the patients whose preoperative OGTT curve was of P type recovered uneventfully after hepatectomy, but those whose curve was of L type of tolerated poorly to hepatectomy and were liable to postoperative hepatic failure and complications. The severity of cirrbosis in those poor risk patients fell to C III or C IV histological degree. 29 patients with intermediate feature of OGTT curve between P type and L type, i.e. I type underwent regional vascular occlusion at hepatic hilus as hepatectomy, and infusion of Danshen extract solution before vascular occlusion to prevent hepatocytes from reperfusion injury. Of them, 20 recovered uneventfully, 8 suffered from complications such as ascites and/or juandice, and 1 died within 1 month after operation. The followup study showed that the survival time of patients with P type OGTT curve was longer than that of I type, and the latter was longer than that of L type. The pattern of OGTT curve could change from preoperative P type to postoperative L type, depending on the severity of vascular interruption of liver and the ischemic injury to hepatocytic mass in operation.

Adolescent↗
PubMed1997

The determinative role of intraoperative echo in tricuspid valvuloplasty.

A transesophageal echocardiography (TEE) was used in monitoring the operation of tricuspid valvuloplasty. Nine patients with rheumatic heart disease were studied. The results showed that intraoperative TEE was important on the improving method of tricuspid annuloplasty, it help to determine surgical procedure, control annulus-reducing procedure and assess the result immediately after operation. The results suggested that intraoperative TEE can be widely used in valvuloplasty in future.

Adult↗
PubMed1997

Polymorphisms of vitamin D receptor gene and its association with bone mineral density and osteocalcin in Chinese.

OBJECTIVE: To explore the distribution frequencies of vitamin D receptor (VDR) gene polymorphisms in Chinese and the relationship between VDR genotypes and bone mineral density (BMD) or serum osteocalcin level in Chinese women. METHODS: Polymorphisms of VDR gene were analyzed by polymerase chain reaction (PCR) to amplify the DNA sequence and three restriction enzymes (namely BsmI, ApaI and TaqI) to digest the PCR products in 223 subjects. Some of the VDR genotypes were also confirmed by Southern hybridization analysis. BMD was measured at the spine and proximal femur by dual-energy X-ray absorptiometry (DEXA). Serum osteocalcin concentrations were determined by radioimmunoassay. RESULTS: Chinese had high frequencies of "b,a,T" alleles, 95%, 75% and 95% respectively, which were much different from Caucasians. "BB" or "AA" genotype had tendency for higher BMD at some sites in the group of young women, whereas in the group of postmenopausal women, "bb" or "aa" genotype had relationship with lower BMD at femoral neck and trochanter. Furthermore, no relationship were found between VDR genotypes and the serum osteocalcin level in Chinese women. CONCLUSIONS: Allele frequencies of VDR gene in Chinese are different from those in Caucasians. VDR gene polymorphisms are associated with BMD in Chinese, but in a different pattern from other reports. Further study on predicting function of VDR for osteoporosis is necessary.

Adult↗
PubMed1997

[Changes of calcitonin reserve function in patients with primary osteoporosis].

In order to study the role of calcitonin (CT) in osteoporosis, the calcium loading calcitonin stimulated test (calcium element 3 mg/kg body weight, i.v., 10 min) was used to investigate calcitonin reserve function in 21 women with osteoporosis. The sesults were compared with those in 48 healthy women and 7 women with osteopenia. After calcium infusion, there was no significant difference in the basal CT, the peak CT value, the CT increase range, and the area under the curve (AUC) between pre- and post-menopausal healthy women. In patients with primary osteoporosis, the four parameters were significantly lower than those in normal controls, and the CT peak value and increase range were lower than those in patients with osteopenia. In the osteopenia group, the basal CT value and its AUC were lower than those in the age-matched control group, but no difference was found in the peak CT value and the increase range between the two groups. The results showed no evident effect of menopause on calcitonin reserve function, but suggested a possible relationship between the decrease of CT reserve function and osteoporosis in patients with osteoporosis. Calcitonin deficiency has something to do with the development of osteoporosis.

Aged↗
PubMed1996

Norepinephrine-induced sustained myocardial adaptation to ischemia is dependent on alpha 1-adrenoceptors and protein synthesis.

The authors have shown that stimulation of cardiac alpha 1-adrenoceptors confers immediate cardioprotection in the isolated rat heart against post-ischemic dysfunction, and have recently demonstrated that in vivo treatment of rats with norepinephrine (NE) induces cardiac heat shock protein 72 and myocardial adaptation to ischemia 24 h after treatment. To characterize the delayed myocardial adaptive response induced by NE further, the present study examined its time course and effects of adrenoceptor antagonism and protein synthesis inhibition on this adaptive response during optimal myocardial protection. Rats were treated with NE (3.1 mumol/kg, i.p.) or normal saline (0.4 ml, i.p.), and hearts isolated at 2, 4, 24, 72 and 168 h after injection. Isolated hearts were subjected to 25 min of normothermic global ischemia and 40 min of reperfusion by the Langendorff technique, and left ventricular developed pressure (LVDP) was assessed. There was no difference in baseline LVDP among groups. Post-ischemic LVDP recovered to 44.7 +/- 2.1 mmHg in pooled saline control. LVDP was significantly improved in hearts isolated at 4, 24 and 72 h after injection of NE (66.3 +/- 3.8, 68.6 +/- 2.7 and 72.6 +/- 8.3 mmHg, respectively, P < 0.05 v control) but not in hearts isolated at 2 or 168 h. Effects of antecedent adrenoceptor antagonism and protein synthesis inhibition were examined in hearts isolated at 72 h after NE treatment. Prazosin pretreatment (2.4 mumol/kg, i.p.) abolished the delayed myocardial adaptive response induced by NE at 72 h (post-ischemic LVDP 48.3 +/- 6.1 mmHg, P > 0.05 v control) while propranolol pretreatment (3.4 mumol/kg, i.p.) had no effect (post-ischemic LVDP 67.3 +/- 3.7 mmHg, P < 0.05 v control). Cycloheximide pretreatment (3.6 mumol/kg, i.p.) also abolished the beneficial effect of NE at 72 h (post-ischemic LVDP 50.2 +/- 6.0 mmHg, P > 0.05 v control). In conclusion, administration of NE to rats can induce delayed and sustained cardioprotection against post-ischemic myocardial dysfunction. NE-induced myocardial adaptation to ischemia at 72 h is mediated by alpha 1-adrenoceptors and appears to require protein synthesis.

Adaptation, Physiological↗
PubMed1996

A single endotoxin challenge induces delayed myocardial protection against infarcation.

Sublethal endotoxemia attenuates cardiac functional injury from global ischemia but it is unknown whether endotoxemia can protect myocardium against infarction. Furthermore, increases in myocardial catalase and heat shock protein (HSP) following endotoxemia have been associated with cardiac ischemic protection. We therefore hypothesized that a 72-hr pretreatment with endotoxin (ETX) would reduce myocardial tissue necrosis in association with augmented catalase activity and stress protein expression. Rabbits were treated with normal saline or lipopolysaccharide (Salmonella typhimurium) at 10, 5, and 1 microgram/kg doses. Three days after saline or ETX injection they were subjected to 45 min of coronary artery occlusion followed by 3 hr of reperfusion. Area of necrosis (tetrazolium staining) was normalized to anatomic risk zone size (Evans blue staining). Catalase activity was measured by a standard assay and HSP 72 was assessed by immunohistochemistry. During regional ischemia and reperfusion there were no differences in heart rate or mean arterial blood pressure between groups. ETX treated rabbits had the same risk zone size as controls. Infarct size was reduced in the ETX treated rabbits at the 10 and 5 microgram/kg doses compared with control rabbits (17.5 +/- 1.5% and 22.2 +/- 3.1% vs 45.3 +/- 2.5%; P < 0.05) but no protective effect was observed at the 1.0 micrograms/kg dose (38.0 +/- 4.6%; P > 0.05 vs control). Catalase activity was not different between control and ETX (5 microgram/kg) treated groups (997.8 +/- 59.1 U/g vs 1099.6 +/- 69.3 U/g myocardium; P > 0.05) but endotoxin induced expression of myocardial HSP 72. We conclude that a single challenge with endotoxin can induce delayed myocardial protection against infarction in vivo. This delayed cardioprotective response involves enhanced stress protein expression without changes in myocellular catalase activity.

Animals↗
PubMed1996

Alpha-adrenergic preservation of myocardial pH during ischemia is PKC isoform dependent.

alpha-adrenergic stimulation of patients with ischemic heart disease should intuitively impose a destructive stress. However, therapeutic alpha1-adrenergic receptor mediated cardioadaptation prior to myocardial ischemia protects ventricular mechanical function, promotes electrophysiologic stability, and preserves myocyte viability. Prior to an anticipated cardiac ischemic insult, alpha1-adrenergic preconditioning attenuates ischemic myocardial acidosis by a protein kinase C-(PKC) dependent mechanism. The alpha1-adrenoceptor can directly stimulate calcium-independent nPKC isoforms via diacylglycerol (DAG) or indirectly stimulate calcium-dependent cPKC isoforms through the release of intracellular calcium via inositol triphosphate, (IP3). We hypothesized that alpha1-adrenergic limitation of ischemic acidosis is mediated by the family of calcium-dependent PKC isoforms. [31P]NMR spectra were obtained in isolated, buffer perfused rat hearts treated with alpha1-adrenergic stimulation [phenylephrine (PE) 50 microM, 2 min]; PKC blockade [chelerythrine chloride, (Chel) 20 microM]; or stearoyl-arachidonoyl glycerol (SAG, a DAG analogue, 100 microM, 2 min) administered 10 min prior to ischemia. Control hearts were perfused under normoxic conditions for 20 min. All hearts were then subjected to global ischemia (20 min, 37.5 degrees C). Developed pressure (DP) and heart rate were recorded continuously. pHi was obtained from chemical shift of inorganic phosphate. Immunohistochemical staining was utilized to delineate the translocation and activation profiles of specific PKC profiles established with each stimulus. Pre-ischemic alpha1-adrenergic stimulation did attenuate the myocellular hydrogen ion accumulation during sustained normothermic ischemia (6.90 +/- 0.13 vs control 6.54 +/- 0.10; P < 0.05). General PKC inhibition abrogated this effect (end-ischemic pH 6.17 +/- 0.10; P < 0.05 vs control and PE). Ischemic acidosis was not attenuated following selective nPKC stimulation (SAG, 6.48 +/- 0.08; NS vs control). Myocellular immunohistochemical staining revealed translocation of the calcium-independent PKC-epsilon isoform in the calcium-dependent PKC (SAG) group, but not in response to alpha1-adrenergic stimulation. The results suggest that (1) alpha1-adrenoceptor stimulation limits ischemic acidosis, (2) alpha1-adrenergic stimulated attenuation of ischemic acidosis is PKC dependent, (3) direct nPKC stimulation with SAG does not limit ischemic acidosis, and (4) SAG stimulates nPKC-epsilon isoform activation where alpha1-adrenergic stimulation does not. We conclude that alpha1-adrenergic stimulation limits ischemic acidosis by a cPKC-dependent mechanism and that the mobilization of the IP3 arm by receptor stimuli suppresses PKC-epsilon thus permitting the limitation of ischemic acidosis.

Alkaloids↗
PubMed1996

Norepinephrine induces cardiac heat shock protein 70 and delayed cardioprotection in the rat through alpha 1 adrenoceptors.

OBJECTIVE: Previous studies have demonstrated that norepinephrine (NE) confers immediate cardioprotection against ischemia and reperfusion injuries. The present study tests the hypothesis that in vivo treatment with NE induces delayed cardioprotection against postischemic dysfunction in the rat heart which is associated with expression of c-fos and heat shock protein (HSP) 70 in the myocardium. METHODS: Rats were treated with NE (3.1 mumol/kg, ip) and hearts isolated and perfused with a modified Langendorff technique 2 or 24 h after injection. Left ventricular developed pressure (LVDP) and left ventricular end-diastolic pressure (LVEDP) were recorded during 25 min normothermic global ischemia and 40 min reperfusion. Total RNA was extracted from left ventricular tissue at various time points and Northern hybridization was applied to detect c-fos and HSP70 mRNAs. Expression and distribution of c-fos and HSP72 proteins in the myocardium were examined by immunohistochemical staining. RESULTS: In vivo NE treatment improved postischemic recovery of both LVDP and LVEDP in the hearts isolated at 24 h after treatment but not in those isolated at 2 h. LVDP was 68.9 +/- 4.8 mmHg in NE 24 h group at the end of reperfusion in comparison to 43.6 +/- 2.9 mmHg in saline control group (P < 0.01). Pretreatment with prazosin abolished NE-induced cardioprotection while propranolol pretreatment had no effect. Northern analysis demonstrated rapid and transient increases in c-fos and HSP70 mRNAs in the myocardium after NE treatment. Accumulation of c-fos protein was observed at 3 h and increased amount of HSP72 protein was demonstrated at 24 h in the myocardium. Pretreatment of rats with prazosin eliminated NE-induced increase in cardiac HSP70 mRNA. CONCLUSIONS: The results suggest that in vivo treatment with NE upregulates the expression of c-fos and HSP70 in the myocardium and induces delayed protection against postischemic myocardial dysfunction in the isolated rat heart. Induction of both the expression of cardiac HSP70 and the delayed cardioprotection by NE appears to be mediated by alpha 1 adrenoceptors.

Adrenergic alpha-Antagonists↗