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S Tang

Publications and source records attributed to S Tang.

At least 109 records · Page 6Linked to original sources
PubMed1999

Protein sequence analysis using Hewlett-Packard biphasic sequencing cartridges in an applied biosystems 473A protein sequencer.

Protein sequence analysis using an adsorptive biphasic sequencing cartridge, a set of two coupled columns introduced by Hewlett-Packard for protein sequencing by Edman degradation, in an Applied Biosystems 473A protein sequencer has been demonstrated. Samples containing salts, detergents, excipients, etc. (e.g., formulated protein drugs) can be easily analyzed using the ABI sequencer. Simple modifications to the ABI sequencer to accommodate the cartridge extend its utility in the analysis of difficult samples. The ABI sequencer solvents and reagents were compatible with the HP cartridge for sequencing. Sequence information up to ten residues can be easily generated by this nonoptimized procedure, and it is sufficient for identifying proteins by database search and for preparing a DNA probe for cloning novel proteins.

Immunoglobulin G↗
PubMed1999

Helical computed tomography angiography in the evaluation of Chinese living renal donors.

OBJECTIVE: To determine the suitability of helical computed tomography angiography (CTA), recently used in the anatomical evaluation of potential living renal donors (LRDs) in the Caucasian population, for Chinese LRDs. SUBJECTS AND METHODS: Eighteen consecutive potential LRD candidates underwent both CTA and conventional renal angiography (CRA). Results from each were interpreted while unaware of the results from the other. Renal function was monitored after each radiological procedure. RESULTS: Both procedures were able to identify all four accessory renal arteries present. One prehilar branch of < 1 mm in diameter was not recognized on CTA. Renal artery ostial stenosis in one subject with normal blood pressure was identified on CTA, but not on CRA. CTA better delineated the renal venous and parenchymal anatomy and cost 60% less than CRA. There was no change in renal function after either procedure. CONCLUSION: Despite there being few subjects. CTA has potential value as an alternative to CRA for the anatomical assessment of potential LRDs in Hong Kong. Advantages include a short examination time, non-invasiveness and lower cost. CTA may provide an opportunity to living-related and unrelated renal donor transplantation in this conservative Chinese culture.

Adult↗
PubMed1999

The effects of tetramethylpyrazine on the incidence of arrhythmias and the release of PGI2 and TXA2 in the ischemic rat heart.

Pretreatment with tetramethylpyrazine (TMP, 12 mg/kg/day), a drug originally derived from the rhizomes of Ligusticum wallichii, significantly reduced the incidence of ischemia-induced ventricular tachycardia (VT) and fibrillation (VF) from 100% and 50% of control hearts to 41% (p < 0.05) and 0% (p < 0.05), respectively, in the ischemic rat heart. TMP also diminished the incidence of reperfusion-induced VT and VF from 100% and 100% of control hearts to 33% (p < 0.05) and 41% (p < 0.05), respectively. Pretreatment with TMP produced a slight, but significant increase of 6-keto-PGF1 alpha and a decrease of TXB2 production during aerobic perfusion. Ischemia and reperfusion markedly increased the release of 6-keto-PGF1 alpha and TXB2. Pretreatment with TMP significantly enhanced the release of 6-keto-PGF1 alpha and diminished TXB2 outflow following left coronary artery occlusion and reperfusion.

Animals↗
PubMed1999

Comparison of human cervical mucus and artificial sperm penetration media.

The cervical mucus penetration tests aid research and determine the clinical importance of positive sperm antibody tests. Limited availability and variability of human cervical mucus have instigated the search for mucus substitutes for these tests. This study compares sperm migration in cervical mucus with that in artificial media including hyaluronate solution, egg white and albumin Tyrode solution. Results were quantified by measuring the migration distance (the maximum distance of capillary migration from a semen reservoir by spermatozoa after 1 h) and the sperm concentration at half the migration distance. The mean of both measures for cervical mucus and hyaluronate solution were equivalent [4.4 +/- 1.1 (SD) versus 4.3 +/- 1.0 cm and 118 +/- 51 versus 111 +/- 44x10(3)/ml], and higher than in egg white and albumin Tyrode solution. Antisperm antibodies impaired sperm penetration in cervical mucus and hyaluronate solution in a similar manner (r = 0.92). These results suggest that hyaluronate solution sufficiently resembles human cervical mucus in terms of penetrability that it may be used as a substitute for mucus in capillary tube tests of sperm function. The higher penetrability of cervical mucus and hyaluronate solution is probably related to a channelling effect due to their polymeric structure.

Albumins↗
PubMed1999

Clinical features and treatment outcome of idiopathic membranous nephropathy in Chinese patients.

We retrospectively studied the clinical course and treatment outcome of idiopathic membranous nephropathy (IMN) amongst 38 Chinese patients (25 male, 13 female, age 51.6 +/- 14.6 years, follow-up duration 58.2 +/- 51.1 months) who presented over a 10-year review period. Eight never received any form of specific treatment (group I), seven received oral corticosteroid alone for 6-9 months (group II), 17 were given corticosteroid plus cyclophosphamide for 6-12 months (group III), and six were treated with methylprednisolone alternating with chlorambucil every other month for 6 months (group IV). No untoward effect from drugs sufficient to alter the dosage used was recorded. After 6 months of treatment, over 50% of patients went into remission: a significant reduction in proteinuria (p = 0.01, 0.01, 0.02) with a corresponding rise in serum albumin levels (p = 0.01, 0.01, 0.04) was observed in groups II, III, and IV, respectively, but not in group I. During follow-up, one patient in each of groups I, III, IV, and two of group II developed renal function deterioration, which correlated with an abnormal presenting serum creatinine. In six group I and eight group III patients who have been followed for at least 5 years, there was progressive reduction in proteinuria in group III (p < 0.05), but not in group I: serum creatinine has remained unchanged in both groups. IMN runs a benign course in Chinese patients in Hong Kong, with 2.6% of patients going into end-stage renal failure during the study period. Contrary to reports in Caucasians, there is similar treatment response to steroid alone or a combination of steroid and cytotoxic agents.

Aged↗
PubMed1999

Ultrasound biomicroscopic features of anterior proliferative vitreoretinopathy.

PURPOSE: To evaluate the utility of ultrasound biomicroscopy (UBM) in the diagnosis of anterior proliferative vitreoretinopathy (APVR). METHODS: Ultrasound biomicroscopy (frequency, 50 MHz; depth of penetration, 5 mm; resolution, 40 microm) was used to examine 53 eyes of 52 subjects with rhegmatogenous or traumatic retinal detachment (RD). The results were compared with findings during vitrectomy. RESULTS: In 43 eyes (42 patients), RD was detected using UBM, attaining 81% consistency with observations during operation. Among 36 eyes with surgically proved APVR, 33 (92%) had APVR detected by UBM. The UBM images showed shallow RD, circumferential contraction, or anterior displacement around the ora serrata. The anterior displacement could be classified into C-shaped anterior displacement, ciliary body adhesion, and pupil adhesion. Ultrasound biomicroscopy showed that a retinal step was formed on the surface of the ora serrata and the ciliary body. Failure to detect APVR by UBM may be due to severe choroidal detachment or a narrow palpebral fissure that hampers exposure of the ora serrata and the part of the eyeball posterior to it. CONCLUSION: Ultrasound biomicroscopy is a useful tool for the evaluation of APVR, which is difficult by ordinary methods. Ultrasound biomicroscopic images of APVR have typical features that may be used to help guide surgery and estimate prognosis.

Adolescent↗
PubMed1999

Mucosal immunization of cynomolgus macaques with two serotypes of live poliovirus vectors expressing simian immunodeficiency virus antigens: stimulation of humoral, mucosal, and cellular immunity.

Poliovirus live virus vectors are a candidate recombinant vaccine system. Previous studies using this system showed that a live poliovirus vector expressing a foreign antigen between the structural and nonstructural proteins generates both antibody and cytotoxic T-lymphocyte responses in mice. Here we describe a novel in vitro method of cloning recombinant polioviruses involving a hybrid-PCR approach. We report the construction of recombinant vectors of two different serotypes of poliovirus-expressing simian immunodeficiency virus (SIV) antigens and the intranasal and intravenous inoculations of four adult cynomolgus macaques with these poliovirus vectors expressing the SIV proteins p17(gag) and gp41(env). All macaques generated a mucosal anti-SIV immunoglobulin A (IgA) response in rectal secretions. Two of the four macaques generated mucosal antibody responses detectable in vaginal lavages. Strong serum IgG responses lasting for at least 1 year were detected in two of the four monkeys. SIV-specific T-cell lymphoproliferative responses were detected in three of the four monkeys. SIV-specific cytotoxic T lymphocytes were detected in two of the four monkeys. This is the first report of poliovirus-elicited vaginal IgA or cytotoxic T lymphocytes in any naturally infectable primate, including humans. These findings support the concept that a live poliovirus vector is a potentially useful delivery system that elicits humoral, mucosal, and cellular immune responses against exogenous antigens.

Animals↗
PubMed1999

Alterations to both the primary and predicted secondary structure of stem-loop IIIc of the hepatitis C virus 1b 5' untranslated region (5'UTR) lead to mutants severely defective in translation which cannot be complemented in trans by the wild-type 5'UTR sequence.

Cap-independent translation of the hepatitis C virus (HCV) genomic RNA is mediated by an internal ribosome entry site (IRES) within the 5' untranslated region (5'UTR) of the virus RNA. To investigate the effects of alterations to the primary sequence of the 5'UTR on IRES activity, a series of HCV genotype 1b (HCV-1b) variant IRES elements was generated and cloned into a bicistronic reporter construct. Changes from the prototypic HCV-1b 5'UTR sequence were identified at various locations throughout the 5'UTR. The translation efficiencies of these IRES elements were examined by an in vivo transient expression assay in transfected BHK-21 cells and were found to range from 0.4 to 95.8% of the activity of the prototype HCV-1b IRES. Further mutational analysis of the three single-point mutants most severely defective in activity, whose mutations were all located in or near stem-loop IIIc, demonstrated that both the primary sequence and the maintenance of base pairing within this stem structure were critical for HCV IRES function. Complementation studies indicated that defective mutants containing either point mutations or major deletions within the IRES elements could not be complemented in trans by a wild-type IRES.

5' Untranslated Regions↗
PubMed1999

Treatment of membranous lupus nephritis with nephrotic syndrome by sequential immunosuppression.

The optimal therapy for pure membranous lupus nephritis (MLN) with nephrotic syndrome remains controversial. While the risk of progressive renal deterioration may be small, persistent heavy proteinuria leads to the complications of oedema, hypoalbuminaemia, hyperlipidaemia, hypercoagulability, and venous thrombosis. We examined prospectively the efficacy and tolerability of a sequential immunosuppressive regimen in a cohort of 20 patients with nephrotic syndrome due to pure MLN (WHO Class Va and Vb). Initial therapy comprised prednisolone (0.8 mg/kg/d p.o.) and cyclophosphamide (2-2. 5 mg/kg/d p.o.). Prednisolone dosage was gradually tapered to 10 mg/d at 6 months, when cyclophosphamide was replaced by azathioprine (2 mg/kg/d p.o.) as maintenance therapy. Within 12 months of therapy 11(55%) patients had complete remission (CR), 7(35%) patients achieved partial remission (PR) (proteinuria reduced from 6.2+/-4.0 to 2.0+/-1.7 g/24 h, P<0.01), and 2 patients failed to respond. Improvements in proteinuria and serum albumin level were observed after 3-6 months of treatment. Non-responders had lower baseline serum albumin compared to complete responders. Renal function remained stable during follow-up for 73.5+/-48.9 months. 8 patients had disease relapse at 47+/-15 months. Early complications (</=12 months) included herpes zoster (40%), minor respiratory or urinary tract infections (25%), mild leukopenia (15%), and transient amenorrhea (14.3%). 4 of the 20 patients developed pulmonary tuberculosis during follow-up, at 35+/-24 months after the diagnosis of MLN. 8 patients had hyperlipidaemia. Haemorrhagic cystitis, permanent amenorrhea, vascular complications, and mortality were not observed. We conclude that this sequential immunosuppressive regimen is effective in 90% of patients with MLN and heavy proteinuria. Prudent consideration of the benefits and potential side-effects is required to determine the optimal management for individual patients.

Adult↗
PubMed1999

Synergistic effects of cAMP- and calcium-mediated amylase secretion in isolated pancreatic acini from cystic fibrosis mice.

We evaluated pancreatic enzyme secretory response to secretagogues (cAMP- and Ca2+-mediating) involved in exocytosis and in chloride channel activation in an exon 10 knockout cystic fibrosis (CF) mouse model. Experiments were performed in isolated pancreatic acini from liquid-fed Cftr-/- mice (5-6 wk of age) and age-matched Cftr+/+ controls fed a solid or liquid diet. BrcAMP and forskolin alone induced higher amylase secretion (% initial amylase content) in the Cftr+/+ acini than carbachol (p < 0.05). Carbachol and BrcAMP or BrcAMP and forskolin, given in combination, produced additive effects on enzyme secretion in the Cftr+/+ acini. Ca2+- and cAMP-mediated amylase secretion in isolated pancreatic acini from the Cftr-/- mice was no different to that observed in the age- and diet-matched Cftr+/+ animals. However, Cftr-/- pancreatic acini showed a significantly greater amylase response to the combination of BrcAMP and carbachol than the sum of the individual responses in separate experiments (p < 0.05). The amylase response was not different in acini from solid-fed or liquid-fed Cftr+/+ controls. In summary, this study suggests that cystic fibrosis transmembrane conductance regulator is not essential for enzyme secretion as evidenced by no reduction in cAMP-mediated amylase secretion in Cftr-/- mice. The results in Cftr+/+ acini suggest pancreatic enzyme secretion is mediated via multiple intracellular pathways acting in parallel and probably converge at a distal step in the secretory process. However, Cftr-/- pancreatic acini exhibited a synergistic secretory response following stimulation by BrcAMP plus carbachol. The enhanced secretory response may partially contribute to the development of pancreatic dysfunction in CF patients by facilitating occlusion of digestive enzymes in the secretory canaliculus of the pancreatic acini.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1999

Apical proteins stimulate complement synthesis by cultured human proximal tubular epithelial cells.

There is increasing evidence to suggest that the renal tubular epithelium is important in the pathogenesis of progressive renal failure resulting from persistent proteinuria. The role of complement in the progression of chronic renal failure is not well defined. The purpose of this study was to characterize the production of complement by human proximal tubular epithelial cells exposed to serum proteins at the apical surface. Complement C3 gene expression was analyzed by reverse transcription and PCR. C3 protein biosynthesis was confirmed by metabolic labeling followed by immunoprecipitation and quantified by enzyme-linked immunosorbent assay. In the quiescent state, proximal tubular epithelial cells grown on permeable membrane supports secreted C3 predominantly into the apical medium. The addition of 5 mg/ml serum proteins led to an 8.9-fold increase in basolateral C3 secretion and a 2.1-fold increase in apical C3 secretion, altering the ratio of basolateral: apical C3 secretion from 0.44 +/- 0.16 to 1.87 +/- 0.52. C3 mRNA expression was also upregulated in a time- and dose-dependent manner. Serum fractionation demonstrated that the stimulant responsible for these effects was in the molecular weight range 30 to 100 kD. The observed phenomenon was not reproduced when purified human albumin alone was used as the stimulant. These findings could provide a possible mechanism for the link between proteinuria and interstitial fibrosis. This may have potential implications for strategies directed against complement in retarding the progression of chronic renal failure.

Cells, Cultured↗
PubMed1999

Long-term renal allograft recipients from South-east Asia in the pre-cyclosporin era.

The clinical outcome of long-term renal allograft recipients in the Chinese population has not been reported previously. We analysed patients from the pre-cyclosporin era who had grafts that functioned for > 10 years. Forty-five patients (31 men, 14 women; mean age 30, follow-up duration 13.3 years), representing a 10-year graft survival of 53%, were included. Thirty-six patients (80%) received living-related allografts and 9 (20%) received cadaveric or living-unrelated renal transplantation. The mean serum creatinine at last follow-up was 1.36 mg/dl (range, 0.83-4.08). Major posttransplantation complications included: hypertension in 25 (56%), infection in 16 (36%), acute rejection in 15 (33%), lipid disorder in 13 (29%), liver disease in 7 (16%), osteonecrosis in 5 (11%), malignancy in 4 (9%), coronary artery disease in 3 (7%), and diabetes mellitus in 3 (7%). Five grafts were lost: 3 to chronic rejection, and 2 to patients with stable function who died of non-renal causes. Proteinuria correlated strongly with graft function and survival, and marginally with hypertension. In hepatitis B carriers, serum alpha-feto protein is useful in the early detection of hepatocellular carcinoma. We conclude that while patients in the pre-cyclosporin era can survive with excellent graft function beyond the first decade, the risk of complications leading to significant morbidity still remains even when patients are receiving minimal doses of immunosuppression in the second decade.

Adolescent↗
PubMed1999

An experimental investigation of osseointegration and stability of implants used as orthodontic anchorage in dogs.

OBJECTIVE: To investigate osseointegration and stability of three kinds of implants used as orthodontic anchorage in dogs. METHODS: HA-coated, titanium plasma-coated, and uncoated titanium implants were inserted into each femur of two dogs. After a healing period of three months, orthodontic force of 200 g was applied by means of Ni-Ti springs which were connected to the two adjacent implants for two months. Position change of the implant was first measured and then calculated. The shear bond strength of the interface between implant and bone was measured with a push test. After the test, the fracture surface at the interface was observed with a scanning electronic microscope. RESULTS: All implants were stable, without mobility. The highest bond strength and mature bone compactness were found at the interface between HA-coated implant and bone. The other two showed no significant difference in bond strength. However, osseointegration existed at the interface between all three kinds of implants and bone. CONCLUSION: HA-coated, titanium plasma-coated, and uncoated titanium implants can each serve as orthodontic anchorage as well as prosthodontic abutment.

Animals↗
PubMed1999

[The study on the role of apoptosis suppressive gene bcl-2 in the pathogenesis of hemangioma].

OBJECTIVE: To elucidate the relationship between bcl-2 and hemangioma. METHODS: We investigated the expression of bcl-2 in 38 samples of hemangioma (19 cases of capillary hemangioma, 10 cases of cavernous hemangioma, 9 cases of racemose hemangioma) and 6 samples of normal skin by immunohistochemical SP method. RESULTS: The results showed that the expression of bcl-2 was higher in cavernous and racemose hemangioma than in the controls, the expression of bcl-2 was lower in capillary hemangioma than in the controls. The differences were statistically significant. CONCLUSION: It can be deduced from the results that there is an intimate relationship between bcl-2 and the growth of cavernous and racemose hemangioma, and the lower expression of bcl-2 in capillary hemangioma shows that capillary hemangioma may disappear naturally.

Adolescent↗
PubMed1999

[Changes in TGF-beta 1 and type I, III procollagen gene expression in keloid and hypertrophic scar].

OBJECTIVE: The expression of mRNA for TGF-beta 1, type I, III procollagen in keloid and hypertrophic scar was investigated in order to elucidate the pathogenesis of and the difference between keloid and hypertrophic scar. METHOD: Dot-blot hybridization analysis was used to examine the type I, III procollagen and the expression levels of steady-state mRNA. In situ hybridization allowed direct assessment of the distribution of TGF-beta 1 mRNA in the tissue. RESULTS: 1. Our study indicated that the expression level of mRNA for TGF-beta 1 significantly increased in keloid and hypertrophic scar compared with normal scar and normal skin. 2. In keloid tissues, type I precollagen mRNA expression was selectively increased. However, in hypertrophic scar, type I and III collagen mRNAs expressions were simultaneously increased. CONCLUSION: TGF-beta 1 plays an important role in the pathogenesis of keloid and hypertrophic scarring. It implicates that distinct molecular mechanisms are operative in the development of keloid and hypertrophic scarring.

Cicatrix, Hypertrophic↗
PubMed1999

[Signal of the cytoplasmic regions of leukemia inhibitory factor receptor (LIFR) alpha-subunit and gp130 involves Stat3 activation in leukemic U937 cells].

OBJECTIVE: In order to understand the mechanism of proliferation and differentiation of leukemia cells, we investigate the relation between the cytoplasmic regions LIFR alpha-subunit and gp130 and the transcription activator Stat3 in human leukemic U937 cells. METHODS: The cytoplasmic domain was each truncated from the LIFR alpha-subunit and gp130. The truncated forms of LIFR alpha-subunit(gp190EX) and gp130 (gp130EX) which can compete with the wild type receptor for binding to leukemia inhibitory factor (LIF) were expressed on the membrane of U937 cells. The level of Stat 3 and its phosphorylation were estimated by immunoblotting. RESULTS: The increased level of Stat3 and its decreased tyrosine phosphorylation were detected in each group of gp130EX and gp190EX as compared with that in the wild type receptor subunit group. CONCLUSION: The cytoplasmic domains of both LIFR alpha subunit and gp130 involve the induction of Stat3 phosphorylation in U937 cells.

Antigens, CD↗