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Biomedical subjects

S Xu

Publications and source records attributed to S Xu.

At least 451 records · Page 25Linked to original sources
PubMed1995

[Synthesis of S(+)-2-(4-isobutylphenyl) propionic acid by asymmetric hydrolysis of microbial enzyme. II. Reaction conditions and product extraction].

Trichosporon cutaneum 158 exhibited higher sterospecificity to hydrolyze substrate ibuprofen ester. Among the five chosen substrate, asymmetric hydrolysis of methyl ester or isopropyl ester formed S(+)-ibuprofen of 97% ee. While ethyl ester not only gave ee 93% but also showed the highest hydrolytic activity. The optimum pH range for asymmetric hydrolysis was 6.5-7.0. Ability of resolusion was stabler in the range of temperature 28-37 degrees C. This yeast produced intracellular enzyme. Hydrolysis can be carried out by powered cells treated by iced-acetone to improve the specificity of resolution. The product S(+)-ibuprofen can be got with acid-base reaction and organic solvent extraction, unreacted esters can be recovered simultaneously.

Hydrolysis↗
PubMed1995

[A ten-year follow-up observation on serum antibody level in schistosomiasis patients treated with praziquantel].

The detection of the serum antibody in 122 schistosomiasis patients, using enzyme linked immunosorbent assay (ELISA), had been carried out from 1980-1989. The results showed that the potency of serum antibody was on an annual progressive decrease. Before treatment, the rate of ELISA reactive titre above 1:800 was 87.7%, while after treatment it was 21.2% in the first year and 1% in the second year and even lower in the following years. The antibody negative conversion rate with ELISA from the first to the fifth year after praziquantel treatment ranged from 53.2%-95.9%, whereas it was 97.0% in the tenth year. No significant difference was found between the ELISA positive rate in patients treated after 4 years and the false positive rate in normol persons (P > 0.05). The data demonstrate that it took four years after therapy for the noticeable reduction of the residual serum antibody level in patients, and that the ELISA positive reaction titre > or = 1:400 in patients 4 years after treatment might be used as complementary diagnostic index for those uncured patients.

Adolescent↗
PubMed1995

The relation of parathyroid function to pregnancy-induced hypertension.

Parathyrin (PTH) and calcitonin were measured with radioimmunoassay in 39 cases of pregnancy-induced hypertension (PIH) in late pregnancy, 76 cases in normal early pregnancy and 278 cases in late pregnancy without PIH. Markedly increased PTH was noted in the women in late pregnancy, indicating the state of secondary hyperparathyroidism. PTH values in the women in late pregnancy with PIH were higher than those in the normal early pregnancy group, but lower than those in the women in late pregnancy without PIH. The difference between PTH values in the PIH group and late pregnancy without PIH group was of statistical significance (P < 0.05), while no significant difference was seen between calcitonin values of the two groups (P > 0.05). The results suggest that the pathogenesis of PIH may be related to the function of parathyroid.

Calcitonin↗
PubMed1995

[The diagnostic value of cortical evoked potential in spinal cord injury].

From 1983-1992 CEP monitoring in spinal cord injury (SCI) was performed in 312 cases, of them 9 were acute SCI and 303 chronic (cervical spine 57, dorsal 88, T11-L1 136 and lumbar 31). 179 cases were complete paraplegia and 133 incomplete paraplegia. CEP were negative in 175 of 179 complete paraplegia, and the correct diagnosis rate was 97.8%. The false positive rate was 2.2%. The changes of CEP in 133 cases of incomplete paraplegia were prolonged latent period and/or decrease in amplitude. Negative CEP occurred in 5 cases, making the false negative rate to be 3.75%. In case of cervical SCI, the CEP of median nerve was positive when C5 segment was intact, while radial nerve CEP was positive as C6 segment was intact. The ulnar nerve CEP was mostly involved in lower cervical spine injury and in central type of SCI because it is composed of C7, C8 and T1 segments. In dorso-lumbar junction, there was the lower end of the spinal cord with its nerve roots, therefore, the CEP of T11-L1 SCI was performed by stimulating femoral, posterior tibial and common peroneal nerves to decrease false negative rate in incomplete paraplegia. Positive CEP in the femoral nerve and negative in tibial and peroneal nerves indicate recovery of nerve roots of lumbar plexus and no recovery of the spinal cord. Positive CEP in femoral, tibial and peroneal nerves represents recovery of the spinal cord and its roots and negative CEP in all three nerves indicate complete SCI, no recovery of spinal cord and its roots.(ABSTRACT TRUNCATED AT 250 WORDS)

Evoked Potentials↗
PubMed1995

[Surgical treatment of avascular necrosis of the femoral head].

71 patients (83 hips) with avascular necrosis of the femoral head were followed up. The patients had bilateral necrosis (12), and unilateral (59). Their ages ranged from 19 to 71 years. Ficat classification showed stage I for 1 hip, stage II 19 hips, stage III 35 hips, and stage IV hips. According to the severity, the range of motion, the age, and the X-ray appearances, 6 kinds of procedures were used including decompression with bone grafting (32 hips), surface arthroplasty with cartilage (4), surface arthroplasty with fascia (4), replacement of femoral head (7), THA (20), and obturator neuroetomy (16). The follow-up period ranged from 2 years and 3 months to 10 years and 5 months. Postoperative improvement included pain (39.7%), range of motion (21.7%), and walking (33.7%). Among the procedures, decompression with bone grafting showed best results. Treatment revealed better results in stage I, II than in stage III, IV. We emphysize the early diagnosis and management, and choice of procedure should base on the clinical classification.

Adult↗
PubMed1995

Increased vulnerability of hypertrophied myocardium to ischemia and reperfusion injury. Relation to cardiac renin-angiotensin system.

Hearts of pressure-overload hypertrophy show an increased activation of intracardiac renin-angiotensin system which may contribute to ischemia and reperfusion injury. The purpose of this study is to evaluate whether the hypertrophied myocardium is more vulnerable to ischemia and reperfusion injury and to find out its relation to the cardiac renin-angiotensin system. Hypertrophied rat hearts induced by abdominal aortic banding for 6 weeks were subjected to 2 hours of hypothermic ischemic arrest followed by 30 minutes of reperfusion, and their cardiac function recovery was compared with that of sham-operated normal control hearts. The cardiac renin activity and angiotensin II content before ischemia and after reperfusion were determined. It was found that both the pre-ischemic renin activity and angiotensin II level were higher in hypertrophied myocardium than those in the control: ischemia and reperfusion injury increased both renin activity and angiotensin II content in the two groups, but the renin activity and angiotensin II level were further elevated after reperfusion in the hypertrophied hearts than those in the control hearts. Meanwhile, the cardiac function recovery after 30 minutes reperfusion in the hypertrophied hearts was poorer than that in the control. Correlation analysis revealed that there was a negative correlation between the cardiac output recovery and the myocardial angiotensin II content (r = -0.8411, P < 0.001). It is concluded that ischemia and reperfusion injury can activate cardiac renin-angiotensin system in isolated rat heart, which may be responsible for the increased susceptibility of the hypertrophied myocardium to ischemia and reperfusion injury.

Angiotensin II↗
PubMed1995

[Nationwide survey of the distribution of human parasites in China--infection with parasite species in human population].

The infection rate of main species of parasites and their character by first nationwide survey of human parasites was made. The overall infection rate of human intestinal parasite and the infection rate of most species of parasites were higher in females than that in males. The infection rate according to the age group, the highest infection rate was found in the group aged 5-14 years. With regard to the relation between parasitic infections and occupations of the infected persons, the highest infection rates of Ascaris lumbricoides were exhibited in school children, of hookworm and Clonorchis sinensis were in halfpeasants and halfmerchant and vegetable grower; of Trichuris trichiura were in fishers, of Giardia lamblia, Entamoeba histolytica and Taenia were in herdsmen and halfherdsmen and halfpeasants. In this survey it is also shown that each nationality has their main species of parasites. The family clustering of some main parasites were proved by some province/autonomous region/municipality.

Adolescent↗
PubMed1995

Endogenous porphyrins in murine skin and transplanted PAM-212 squamous cell carcinoma tissues after injection of delta-aminolevulinic acid.

After intraperitoneal (IP) injection of delta-aminolevulinic acid (ALA), the endogenous porphyrins in murine skin and tumor tissues were determined by a method involving solvent and acid extractions. The results showed that the total amount of porphyrins in the tumor tissues after ALA injection was much higher than that in the skin from the same mice, although the amount of porphyrins in the skin from the ALA-injected mice was higher than that from the saline-injected (control) mice. The porphyrins in the tumor were mostly protoporphyrin and coproporphyrin, with only a small amount of uroporphyrin. The optimum period for porphyrin accumulation in the tumor as well as in the skin was 1 hour after the injection of ALA. As the period was extended to 3 and 6 hours, the amount of porphyrins in these tissues decreased considerably. These findings could be valuable for further application of ALA in the photodynamic therapy of skin cancer.

Aminolevulinic Acid↗
PubMed1995

Clinical value of urinary and serum pseudouridine in diagnosis and monitoring of primary liver cancer.

Urinary and serum pseudouridine concentrations were determined by high-performance liquid chromatography in 80 patients with primary liver cancer, 32 with benign space occupying lesions of the liver, 42 with liver cirrhosis and 40 healthy subjects. Their mean urinary and serum pseudouridine levels were 39.2 +/- 11.5 nmol/mumol creatinine and 3.4 +/- 1.3 mumol/L, 24.5 +/- 5.4 nmol/mumol creatinine and 2.5 +/- 0.5 mumol/L, 22.8 +/- 7.8 nmol/mumol creatinine and 2.3 +/- 0.4 mumol/L, 26.4 +/- 4.6 nmol/mumol creatinine and 2.3 +/- 0.4 mumol/L, respectively. Exceeding the mean plus 2SD of pseudouridine of healthy control was considered as positive value for the diagnosis of primary liver cancer. Thus the positivity of urinary and serum pseudouridine in hepatoma was 71.3% and 70.0%, respectively. The positive rate of combined pseudouridine and alpha-fetoprotein assay was 91.3% in patients with hepatoma. Besides, pseudouridine levels could elevate before positive localization and reduce to normal levels after tumor resection. The results showed that the determination of pseudouridine is of clinical significance in the diagnosis and monitoring of primary liver cancer.

Biomarkers, Tumor↗
PubMed1995

[Characteristics and recent trends in endemicity of human parasitic diseases in China].

An analysis of the nationwide survey of the distribution of human parasites in the light of the literature previously published, two major trends in the endemicity of parasitic diseases in China was observed. For one trend, the infection rate of E. histolytica, Fasciolopsis buski and soil-transmitted helminthasis etc. declined markedly. The second trend was that the prevalence of food-transmitted parasitic diseases (Trichinella spiralis, Clonorchis sinensis, Paragonimiasis, cysticercosis) and hydatidosis was increasing. The relationship between the social economic factors and the two trends were discussed.

Animals↗
PubMed1995

Relationship between coronary angioscopic and intravascular ultrasound imaging and restenosis.

In order to investigate the relationship between restenosis and the morphology detected by coronary angioscopy (CASC) and introvascular ultrasound imaging (IVUS), 17 patients were detected by CASC and IVUS immediately and 3 months after percutaneous transluminal coronary angioscopy (PTCA). The results showed that the dilation index by IVUS (DIu) was significantly lower in restenosis patients than in non-restenosis patients (0.42 +/- 0.08 versus 0.78 +/- 0.16, P < 0.01) and that the elastic recoil (ER) was higher in restenosis patients than in non-restenosis patients (4.51 +/- 1.42 mm2 versus 1.63 +/- 1.20 mm2, P < 0.01), and that the elastic recoil rate (ERR) was also higher in restenosis patients than in non-restenosis patients (57.3 +/- 8.07% versus 21.80 +/- 16.84% P < 0.01), and that coronary dissection, atheromatous plaque and calcification as well as the colour of inner coronary artery had no relation with chronic restenosis. In conclusion, the elastic recoil is one of the important factors of chronic restenosis after PTCA.

Aged↗
PubMed1995

[Clinical observation on vertical transmission of human papillomavirus].

OBJECTIVE: To observe the possibility of maternal-fetal vertical transmission of human papillomavirus (HPV) via amniotic fluid. METHODS: Specimens of cervical secretions from 30 pregnant women were obtained during the third trimester before rupture of membrane, and specimens of pharyngeal secretions of their neonates were obtained 12-48 hours after birth. Amniotic fluids were collected in 13 pregnant women during cesarean section. The presence of HPV types 6, 11, 16, 18, 31, 33, 35, 38 deoxyribonucleic acid were detected by consensus polymerase chain reaction. RESULTS: HPV deoxyribonucleic acid was found in 16 cervical specimens, 14 pharyngeal specimens and in 3 amniotic fluids, the positive rate was 53.3%, 46.7%, 23.1% respectively. The pharyngeal specimen was also HPV positive in one of the three neonates from the amniotic fluid positive mothers. CONCLUSION: The results indicate that HPV can be transmitted in utero through amniotic fluid and cesarean section can not protect the neonates against vertical transmission completely.

Adult↗
PubMed1995

Radiologic manifestations of osteopetrosis.

The clinical radiologic manifestations of 8 patients with osteopetrosis (4 males and 4 females) are analyzed. Six of the cases are benign. The pathologic basis for the radiologic manifestations is discussed, and a classification is suggested. "Broom-like" metaphyses, metaphyses containing three or four dense layers of bone, and ossification of soft tissues around joints were found and differential diagnosis was made.

Adolescent↗
PubMed1995

[Multiple endocrine neoplasia type III: report of three cases].

Multiple endocrine neoplasia type III (MEN III), or MEN IIb, is a rare syndrome. We have reported 3 typical cases of MEN III since 1987. Their syndrome was characterized by striking appearance of marfanoid habitus and face, multiple mucosal neuromas affecting lips and tongue, medullary thyroid carcinoma. Their family histories were negative. Only the third case of MEN III was correctly diagnosed before operation. Medullary thyroid carcinoma was removed. The first case was followed up for 7 years without recurrence.

Adolescent↗