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Biomedical subjects

S Tang

Publications and source records attributed to S Tang.

At least 181 records · Page 10Linked to original sources
PubMed1996

Immobilization of prostaglandin synthetase by hydrophobic adsorption.

In this article, the immobilization of prostaglandin synthetase on n-alkyl or aryl amino-agar beads by hydrophobic adsorption is reported. The effects of different hydrophobic groups in the agar beads, pH of buffer, concentration of salts on the adsorption of prostaglandin synthetase, and the properties of immobilized prostaglandin synthetase were also studied. The results showed that 20-35 mg of microsome containing PG synthetase (protein content 8-15 mg) could be adsorbed on each gram of n-dodecylamino-agar beads after suction drying the gel in the buffer of pH 5.5 (containing 0.5 mol/L KCl), 0.1 mol/L citric-phosphate at 4 degrees C. The remaining immobilized enzyme activity was over 80%. The optimum pH of immobilized PG synthetase is 8.0, similar to that of the native enzymes. The thermostability of immobilized PG synthetase in the buffer containing 0.5 mol/L KCl was increased. Immobilized PG synthetase was used as a catalyst of synthesis of prostaglandin E1. The preservation of activity after 10 working cycles was 86.2%.

Adsorption↗
PubMed1996

Prostaglandin E1 (PGE1) reduces cardiac-derived TXA2 release in ischaemic arrest in isolated working rat heart.

To determine whether PGE1 plays a beneficial role in crystalloid cardioplegia in the isolated working rat heart, twenty isolated rat hearts were studied. The hearts were subjected to 90 min cardioplegic arrest under hypothermia (25 degrees C) and 30 min reperfusion. Prior to ischaemic arrest, the amount of TXA2 in coronary effluent, left ventricular developed pressure (LVDP), left ventricular end diastolic pressure (LVEDP), coronary flow (CF), aortic flow (AF) and cardiac output (CO) did not differ between the control and PGE1 treated rats (28 nmol/l). However, at 30 min reperfusion, the recovery of LVDP, LVEDP, CF, AF, CO and SV in hearts from PGE1 treated rats was more than in control hearts. TXA2 levels from coronary effluent were increased during reperfusion in control rats. On the other hand, PGE1 (28 nmol/l) inhibited the release of TXA2 at reperfusion. The present studies confirm that the cardiac-derived TXA2 are increased after ischaemia/reperfusion. Infusion of cardioplegia solution containing PGE1 results in the inhibition of release of cardiac-derived TXA2 and in a better preservation of cardiac function after ischaemic arrest.

Alprostadil↗
PubMed1996

Beneficial effects of iloprost cardioplegia in ischemic arrest in isolated working rat heart.

To determine whether the prostacyclin analog iloprost plays a beneficial role in crystalloid cardioplegia in isolated working rat hearts, 20 isolated rat hearts were studied after sustaining 90 min of cardioplegic arrest under hypothermia (20 degrees C). The findings indicated that thromboxane A2 (TXA2) levels in coronary effluent were increased during reperfusion. Iloprost (12 nm/l) inhibited the release of TXA2 and improved the recovery of cardiac hemodynamics after ischemia. These data demonstrated that cardiac-derived TXA2 appeared to mediate reperfusion injury after prolonged aortic clamp or cardiac transplantation and iloprost cardioplegic infusion resulted in the inhibition of release of cardiac-derived TXA2 and in a better preservation of cardiac function after ischemic arrest.

Animals↗
PubMed1996

Rapid and reliable method for the determination of aluminium in bone by electrothermal atomic absorption spectrometry.

A reliable method for the determination of aluminium in bone by electrothermal atomic absorption spectrometry (ETAAS) is described. Bone samples were digested in concentrated HNO3 using a closed-vessel microwave digestion system. Accurate and precise results were obtained by calibration against aqueous Al standards prepared in solutions containing 1% v/v HNO3 and 1.0 g l-1 Ca, as Ca(NO3)2, as modifier. No modifier was needed for the bone digestate. A method detection limit (3 sigma) of 0.023 microgram g-1 for bone was obtained. The between-day precision for bone digestate was about 7% at a mean concentration of 10 micrograms l-1. The method was validated against the NIST standard reference materials SRM 1486 Bone Meal and SRM 1577b Bovine Liver. To help confirm the concept of the Al in bone method, essentially the same method, with some minor modifications, was used for the determination of Al in serum and dialysis fluid. The method performance was monitored by participation in two international interlaboratory comparison programmes for serum and dialysis fluid Al available from Canada (CHUL, Québec) and the UK (Robens Institute). The performance over a 10 month period was excellent for both serum and dialysis fluid proficiency test samples distributed by these programmes.

Aluminum↗
PubMed1996

Pretreatment with tetramethylpyrazine increases the release of PGI2 and decreases TXA2 release in isolated rat heart.

We investigated the release of PGI2 and TXA2 by measuring their stable metabolites of 6-keto-PGF1a and TXB2 in the perfusate in the isolated rat heart after pretreatment with tetramethylpyrazine (TMP). Pretreatment with TMP (12 mg/kg, i.p.) 7 days before preparation produced a significant elevation of 6-keto-PGF1a from 2.30 +/- 0.65 ng/min/g of untreated controls to 3.8 +/- 0.77 ng/mir/g (p < 0.05). Pretreatment with TMP also decreased TXB2 release (p < 0.05 versus control).

6-Ketoprostaglandin F1 alpha↗
PubMed1996

Pay Status as a Predictor of Outcome in Surgical Treatment of Obesity.

BACKGROUND: Higher complication rates and lower success in surgery for severe obesity have been reported for patients with government pay status. We examined the effect of pay status upon outcome in surgical treatment of obesity. METHODS: This was an observational study from an aggregate data set of individual patient information. Government pay status (G) was defined as full or partial medical care payment through Medicare, Medicaid, or Veterans Administration. Payment entirely by private insurance was defined as private (P). Operations were classified as either simple (S, gastric restriction) or complex (C, gastric restriction with small bowel bypass). Two measures of outcome, perioperative complication rate and weight loss success (</= 50% excess weight), were examined to determine pay status effect. RESULTS: More G than P patients were treated with simple procedures (79% vs 51%, p < 0.05). Perioperative complication rates were more common for G than P patients (14.4% vs 9.1%, p < 0.05). One-year weight loss success was higher for P than G, regardless of operation type. CONCLUSION: Pay status should be included in characterization of patient groups and in the analysis of results when effectiveness of surgical treatment for severe obesity is reported.

Journal Article↗
PubMed1996

The insulin-mimetic agent vanadate promotes receptor endocytosis and inhibits intracellular ligand-receptor degradation by a mechanism distinct from the lysosomotropic agents.

Vanadate (sodium orthovanadate) is an insulin-mimetic agent and phosphotyrosine phosphatase inhibitor that has been proposed as a potential therapeutic agent for diabetes. We previously reported that vanadate decreased the number of cell-surface insulin receptors but inhibited receptor degradation in cultured lymphocytes (IM-9) (1). To determine whether vanadate affected receptors without intrinsic tyrosine kinase activity, its effects on LDL and transferrin receptors and their ligands were examined. Vanadate exposure resulted in a dose- and time-dependent decrease in LDL binding to cultured human fibroblasts associated with a decrease in cell surface receptor number while total solubilized cell LDL receptors increased. Vanadate also inhibited the LDL-mediated downregulation of total cellular LDL receptors in the absence and presence of cycloheximide consistent with an inhibition of LDL receptor degradation. In the case of the ligand, vanadate augmented the accumulation of intact 125I-LDL associated with an inhibition of up to 80% of the ability of LDL to decrease cholesterol synthesis. Since these actions were similar to the effects of lysosomotropic agents, we examined the effect of vanadate on intraendosomal pH using the fluorescent probe acridine orange. In contrast with chloroquine and NH4Cl, vanadate did not neutralize the pH of the acidic intracellular compartment. Furthermore, after a transient insulin-like effect, chronic exposure to vanadate diminished 125I-diferric transferrin binding to rat adipocytes. In contrast with the inhibitory action of NH4Cl, intracellular 59Fe uptake remained unaffected and was proportional to cell-surface binding capacity in the presence of vanadate. These data demonstrate a chronic effect of vanadate to promote the accumulation of intracellular receptors and to inhibit ligand and receptor degradation. The latter effect is not mediated by pH changes, appears to be localized to a late endosomal/lysosomal compartment, and suggests a possible role for tyrosine dephosphorylation in the regulation of receptor-ligand degradation.

Adipocytes↗
PubMed1996

Effects of high-voltage galvanic stimulation of ST36 and ST37 acupuncture points on peripheral blood flow and skin temperature.

In traditional Chinese medicine, ST36 and ST37 acupuncture points are commonly recommended to enhance peripheral blood circulation and digestive functions; however, there is a paucity of empirical data in support of the above recommendations. This study was designed to evaluate the effects of transcutaneous electrical stimulation of ST36 and ST37 acupuncture points on peripheral haemodynamic functions. Eleven healthy subjects (five men, six women; mean age 28 years), voluntarily participated in the study. A 2 (pulse frequency) x 3(time-frame) experimental design was employed. The subjects' ST36 and ST37 acupuncture points were stimulated, at sensory threshold intensity, with the high-voltage galvanic (HVG) current using two (5 Hz and 120 Hz) different pulse frequencies. Skin temperature and haemodynamic functions (cutaneous blood flow, microvascular volume and erythrocyte velocity), between the first and second metatarsals of the subjects' dominant foot were monitored every 2 min, for 10 min at rest, during 20 min HVG stimulation treatment and 10 min post-stimulation. The results of the repeated-measures analysis of variance revealed no significant F-ratio for pulse frequency and time-frame main effects for any of the dependent variables. Based on our findings we conclude that percutaneously applied HVG stimulation of ST36 and ST37 acupuncture points does not increase peripheral haemodynamic functions in asymptomatic subjects.

Adult↗
PubMed1996

[A preliminary study of biochemistry of patients with crystalline retinopathy].

PURPOSE: To investigate the pathogenesis and biochemical changes of crystalline retinopathy by detecting and analyzing the levels of trace elements (Cu++ and Zn++), blood-lipids and free amino acids in the serum of patients. METHODS: Blood samples of 10 patients with crystalline retinopathy and 30 normal subjects were collected. The levels of serum Cu++ and Zn++ were detected by using flame atomic absorption spectrometry, while cholesterol and triglyceride were detected by direct colordeveloping process and acetyl-acetone developing process respectively and serum amino acids by the Beckman amino acid analyzer. RESULTS: In comparison with the normal control group, the level of Zinc in serum was much decreased in the crystalline retinopathy group, while Cu++/Zn++ ratio and total cholesterol level in serum were significantly increased. In 3 out of 4 patients the level of taurine is lower than that of control group. CONCLUSION: The decrease of serum trace elements and taurine and the increase of cholesterol may be one of the important factors for the pathological changes of crystalline retinopathy. The administration of trace elements e. g. Zn++ and taurine might be a new therapy for the patients.

Adult↗
PubMed1996

Macrophages in human epiretinal and vitreal membranes in patients with proliferative intraocular disorders.

PURPOSE: Macrophages are versatile cells and have been known as a cellular component of epiretinal membranes of proliferative intraocular disorders (PID). However, the origin and functions of these cells in the membranes are not yet clear. In the present study we investigated the characterization of macrophages/monocytes in various types of human epiretinal membranes from patients with proliferative vitreortinopathy (PVR), proliferative diabetic retinopathy (PDR) and ocular perforating injury by means of immunohistochemical techniques. METHODS: A total of 49 epiretinal membranes of PID in which 24 were PDR specimens, 17 were PVR and 8 were proliferations after perforating eye injury were studied. Monoclonal antibodies against human macrophages, monocytes, HLA-DR antigen and interleukin-1 (IL-1) were used. The alkaline phosphatase anti-alkaline phosphatase (APAAP) technique was performed. RESULTS: The results showed that 19 out of 24 PDR specimens (79%), 15 out of 17 PVR specimens (88%) and 7 out of 8 traumatic specimens (87%) contained macrophages, HLA-DR antigen was detected in 20 out of the 24 PDR membranes (83%), 14 out of 17 PVR membranes (82%) and 5 out of 8 traumatic membranes (63%); monocytes were only detected in 10 out of the 24 PDR specimens (41%). In addition, in a group of PDR specimens, interleukin-1 (IL-1) was detected in 8 out of 13 tested specimens (62%). CONCLUSION: The results revealed that the macrophages in the membranes were in an active stage and may play a significant role in the development of proliferative intraocular disorders through either inducing inflammatory reactions or immune responses, or the effects of their cytokines.

Diabetic Retinopathy↗
PubMed1996

[Restriction fragment length polymorphism assays of clinical isolated human cytomegalovirus strain genomic DNA].

Ten clinical isolated strains of Human cytomegalovirus (HCMV) were obtained from 73 urine specimens of different people. Isolations from urine were carried out in human embryolung fibroblasts. Viral isolates were passaged four times. HCMV DNAs of laboratory strain AD169 and 10 clinical isolated strains were extracted with Hirt method, digested with each of the restriction enzymes EcoRI, Hind II. Comparison of restriction fragment length polymorphism (RFLP) of AD169 and isolated strains were made by hybridizing digested DNA with 32P labeled with HCMV Hind II cloned subgenomic fragments as the probe (pCM1035, pCM1015). pCM1035 is located in the joining region between the long(L) and short (S) unique sequences of the virus (L-S junction) pCM1015 is located in the terminal sequences of the virus. The results showed the genomic high degree of homology existed among all strains and the variable restriction site was in the L-S junction and terminal portion. The RFLP patterns of the clinical isolates which did not have relation in epidemiology were different, but the patterns of clinical isolates related in epidemiology were quite similar. Polymorphism frequently occurred in this case of EcoRI digested fragment hybridized with the probe of pCM1035. Southern hybridization of HCMV isolations is useful to researches into the molecular epidemiology and pathogenesis of HCMV infection.

Adult↗
PubMed1995

Spectroscopic study of the interaction of aluminum ions with human transferrin.

Transferrin is the plasma protein responsible for transporting Fe3+ from the absorption to the utilization site. Interactions of apo- and holo-transferrin with Al3+ were studied by circular dichroism (CD), UV-visible, and fluorescence spectrometry. Binding of Al3+ to both metal-ion binding sites of apo-transferrin was confirmed by fluorescence studies. No interaction of Al3+ with holo-transferrin was observed, indicating that Al3+ cannot displace Fe3+ under the experimental conditions employed. An increase in tryptophan fluorescence (lambda max at 330 nm) by excitation at either 280 or 295 nm was observed after Al3+ interaction with apo-transferrin. There was no shift in wavelength of the fluorescence band of apo-transferrin after interaction with Al3+, but the intensity did increase. Since excitation at 295 nm is specific for tryptophan residues, tryptophan but not tyrosine must be responsible for the change in fluorescence intensity. Decreased fluorescence is the result of Fe3+ binding to apo-transferrin. The CD spectrum of apo-transferrin was slightly affected in the far UV by Al3+ binding, but a salient change was noted in the near UV at approximately 288 nm where tyrosine and tryptophan absorb. It is concluded that a small conformational change in the protein was induced by Al3+ binding to apo-transferrin.

Aluminum↗
PubMed1995

The optimal binding sequence of the Hox11 protein contains a predicted recognition core motif.

HOX11 is a homeobox-containing oncogene of specific T-cell leukemias. We determined the DNA binding specificity of the Hox11 protein by using a novel technique of random oligonucleotide selection developed in this study. The optimal Hox11 binding sequence, GGCGGTAAGTGG, contained a core TAAGTG motif that is consistent with a prediction based on the residues at specific positions that potentially make DNA base contacts and models of homeodomain-DNA interaction proposed from studies with other homeodomains. The specific interaction between Hox11 and the selected optimal binding sequence was further confirmed by band-shift and DNA competition assays. Given that the Hox11 homeodomain shares low homology with other well studied homeodomains, the presence of a predictable recognition core motif in its optimal binding sequence supports the notion that different homeodomains interact with DNA in a similar manner, through highly conserved residues at specific positions that allow contact with DNA.

Amino Acid Sequence↗
PubMed1995

Prospective evaluation of associations between hearing sensitivity and selected cardiovascular risk factors.

The prospective decline of hearing sensitivity was evaluated in an occupational cohort of university blue collar workers in relation to age, gender, occupational and nonoccupational noise exposure, smoking, blood pressure, and cholesterol. Each of these were associated with loss of hearing sensitivity univariately. When controlling for age and historical noise exposure in a multiple regression model, systolic blood pressure and cholesterol level were independently associated with decline in auditory sensitivity.

Cardiovascular Diseases↗