Biomedical subjects

W Tian

Publications and source records attributed to W Tian.

At least 55 records · Page 3Linked to original sources

PubMed2000

Production of polyesters consisting of medium chain length 3-hydroxyalkanoic acids by Pseudomonas mendocina 0806 from various carbon sources.

Pseudomonas mendocina strain 0806 was isolated from oil-contaminated soil and found to produce polyesters consisting of medium chain length 3-hydroxyalkanoates (mclPHAs). The monomers of mclPHAs contained even numbers of carbon atoms, such as 3-hydroxyhexanoate (HHx or C6), 3-hydroxyoctanoate (HO or C8), and/or 3-hydroxydecanoate (HD or C10) as major components when grown on many carbon sources unrelated to their monomeric structures, such as glucose, citric acid, and carbon sources related to their monomeric structures, such as myristic acid, octanoate, or oleic acid. On the other hand, PHA containing both even and odd numbers of hydroxyalkanoates (HA) monomers was synthesized when the strain was grown on tridecanoic acid. The molar ratio of carbon to nitrogen (C/N) had a significant effect on PHA composition: the strain produced PHAs containing 97-99% of HD monomer when grown in a glucose ammonium sulfate medium of C/N<20, and 20% HO, and 80% of the HD monomer when growth was conducted in media containing C/N>40. It was demonstrated that the HO/HD ratio in the polymers remained constant in media with a constant C/N ratio, regardless of the glucose concentration. Up to 3.6 g/L cell dry weight containing 45% of PHAs was produced when the strain was grown for 48 h in a medium containing 20 g/L glucose with a C/N ratio of 40.

Glucose↗

PubMed2000

Ras signaling in the inner medullary cell response to urea and NaCl.

The small guanine nucleotide-binding protein Ras, activated by peptide mitogens and other stimuli, regulates downstream signaling events to influence transcription. The role of Ras in solute signaling to gene regulation was investigated in the murine inner medullary collecting duct (mIMCD3) cell line. Urea treatment (100-200 mM), but not sham treatment, increased Ras activation 124% at 2 min; the effect of NaCl did not achieve statistical significance. To determine the contribution of Ras activation to urea-inducible signal transduction, mIMCD3 cells were stably transfected with an expression plasmid encoding a dominant negative-acting N17Ras mutant driven by a dexamethasone-inducible (murine mammary tumor virus) promoter. After 24 h of induction, selected cell lines exhibited sufficient N17Ras overexpression to abolish epidermal growth factor- and hypotonicity-mediated signaling to extracellular signal-regulated kinase (ERK) phosphorylation, as determined by immunoblotting. Conditional N17Ras overexpression inhibited urea- and NaCl-inducible ERK phosphorylation by 40-50%, but only at 15 min, and not 5 min, of treatment. N17Ras induction, however, almost completely inhibited urea-inducible Egr-1 transcription, as quantitated by luciferase reporter gene assay, but failed to influence tonicity-inducible (TonE-mediated) transcription. N17Ras overexpression also blocked urea-inducible expression of the transcription factor Gadd153 but did not influence osmotic or urea-inducible apoptosis. In addition, urea treatment induced recruitment of the Ras activator Sos to the plasma membrane. Taken together, these observations suggest a role for Ras signaling in the IMCD cell response to urea stress.

Animals↗

PubMed2000

Urea protects from the proapoptotic effect of NaCl in renal medullary cells.

Hypertonic NaCl upregulated two sensitive and specific biochemical indices of apoptosis, caspase-3 activation and annexin V binding, in a time- and dose-dependent fashion in renal medullary mIMCD3 cells. Pretreatment with urea (200 mM for 30 min) protected from the proapoptotic effect of hypertonic stress (200 mosmol/kgH(2)O) in this model. The protective effect of urea was dose dependent and was effective even when applied a short time (< or =1 h) following NaCl exposure; this protective effect was not observed in the nonrenal 3T3 cell line. In both mIMCD3 and 3T3 cells, urea failed to protect from the proapoptotic stressor, ultraviolet (UV)-B irradiation. The ability of urea to protect from hypertonic stress was approximately comparable to the protective effect of peptide mitogens epidermal growth factor and insulin-like growth factor (IGF), but it potentiated the IGF effect. Interestingly, the tyrosine kinase inhibitor, genistein, potentiated the proapoptotic effect of urea yet abrogated the proapoptotic effect of hypertonic stress. In aggregate, these data indicate that urea protects from the proapoptotic effect of hypertonic stress in a potentially cell type-specific and stimulus-specific fashion.

3T3 Cells↗

PubMed2000

MAPK signaling and the kidney.

Following an overview of the biochemistry of mitogen-activated protein kinase (MAPK) pathways, the relevance of these signaling events to specific models of renal cell function and pathophysiology, both in vitro and in vivo, will be emphasized. In in vitro model systems, events activating the principal MAPK families [extracellular signal-regulated and c-Jun NH(2)-terminal kinase and p38] have been best characterized in mesangial and tubular epithelial cell culture systems and include peptide mitogens, cytokines, lipid mediators, and physical stressors. Several in vivo models of proliferative or toxic renal injury are also associated with aberrant MAPK regulation. It is anticipated that elucidation of downstream effector signaling mechanisms and a clearer understanding of the immediate and remote upstream activating pathways, when applied to these highly clinically relevant model systems, will ultimately provide much greater insight into the basis for specificity now seemingly absent from these signaling events.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Anatomical variation of the posterior interosseous nerve: a cadaver dissection study.

An anatomical variation of the posterior interosseous nerve was found in a cadaver. The posterior interosseous nerve entered the supinator muscle 3 cm distal to the radiohumeral joint, but exited from two sites. Fifty percent of the nerve exited under the distal edge of the supinator muscle. The other 50% of the nerve pierced through the supinator muscle, 4.2 cm distal to the articular surface of the radial head and then joined the remaining posterior interosseous nerve as it emerged from the supinator muscle distally. Variations were not found concerning the order and the manner of branches to the muscles. This variation in the posterior interosseous nerve could be an additional compression site for this nerve and therefore responsible for some of the atypical presentations of symptoms and for partial recovery after surgical decompression. Careful surgical dissection is recommended to avoid injury to this branch.

Aged↗

PubMed2000

The Oklahoma repair technique: a biomechanical study of a new suture repair technique.

We designed and evaluated the biomechanical advantages of a new (Oklahoma) suture technique for repairing flexor tendons in fresh, frozen cadaver specimens. Forty flexor digitorum profundi tendons from the middle three fingers were sharply cut and repaired with a number 3-0 braided polyester using the new technique and the Modified Kessler technique with and without an epitenon repair. The repaired tendons were then stressed to failure. The Modified Kessler with epitendon repair initiated gap formation on an average of 15.3 +/- 2.7 newtons and failed at 40.9 +/- 4.3 newtons. The Oklahoma suture technique with a running epitenon repair initiated gap formation on average of 48.6 (SD +/- 4.0) newtons and required an average load of 57.9 (SD +/- 3.0) newtons to fail. Thus, it was significantly stronger than the modified Kessler technique with epitendon repair (P < 0.01). The tendons repaired with the Oklahoma and epitenon repair suture technique did not form a 2 mm gap prior to failure. The epitendon repair increased the resistance to gap formation by 80% to 100% and the repair failure by 17.5% to 25% for both types of repairs. We concluded that the addition of the epitendon repair increases the tensile strength of the repair regardless of the core suture technique, and it should be used. In comparison with the Modified Kessler repair technique, the Oklahoma repair technique has superior tolerance to gap initiation, 2 mm gap formation, and physical failure of the repaired tendon.

Analysis of Variance↗

PubMed2000

[Clinical diagnosis of apical hypertrophic cardiomyopathy].

OBJECTIVE: To evaluate the clinical features of apical hypertrophic cardiomyopathy (AHCM) and the value of ECG for a reliable clinical diagnosis as compared with two-dimensional echocardiography. METHODS: 29 cases with AHCM were studied by with clinical features, ECG, echocardiography, myocardial scanning, coronary angiography and left ventriculography (LVG). RESULTS: The major clinical feature of AHCM was myocardial ischemia; ECG showed increased R amplitude and inverted T in chest leads. The increase of R amplitude was in such a pattern that RV(4)>or=RV(5) > RV(3). Thickening of left ventricular apical wall was found with echocardiography and radionuclide myocardial scanning. Exercise electrocardiogram showed myocardial ischemia in 20 cases. LVG and coronary angiography demonstrated apical hypertrophic cardiomyopathy with normal coronary arteries in 16 cases. CONCLUSION: The characteristic inverted T waves and increased R wave amplitude with RV(4)>or=RV(5 > RV3) in the ECG are the important signs for clinical diagnosis of AHCM.

Adult↗

PubMed2000

[Molecular cytogenetics of bone tumors].

OBJECTIVE: To study alterations of molecular cytogenetics of bone tumor serially. METHODS: Chromosomal analysis, immunohistochemistry, molecular hybridization, nested-PCR/SSCP, DNA sequence analysis, and gene transfection techniques were used to investigate the common bone tumors. RESULTS: Chromosomal aberrations were found in 50 cases of aggressive bone tumors, with a chromosome number aberration rate of 86.96% and a structure aberration rate of 93.94%. However, there were differences among different kinds of bone tumors. The incidence of chromosomal instability in 53 patients with bone tumors was higher than that in normal controls. Meanwhile, the fragile sites of chromosomes of the patients were closely correlated with the high nonrandom chromosome breakpoints of tumor cells and related oncogene loci. The data on p53 and Rb from 305 cases and 89 cases, respectively, indicated that abnormalities of p53 and Rb were common events in bone tumors. The accumulation of p53 protein and loss of Rb protein were more common in aggressive bone tumors. Structures and their products of related proto-oncogenes (ras, myc, fos, bcl-2, met) were studied in 124 cases. Bone tumors presented multi-oncogenes abnormalities with differences in different pathological kinds. Exogenous wild-type p53 gene transfected into osteosarcoma cell line induced growth inhibition and apoptosis of tumor cells. CONCLUSIONS: Abnormalities of chromosomes, proto-oncogenes, and tumor suppressor genes frequently exist in bone tumor cells and are correlated with oncogenesis.

Bone Neoplasms↗

PubMed2000

[Cervical spine operation using coralline hydroxyapatite].

OBJECTIVE: To study the result of using coralline hydroxyapatite (CHA) in cervical anterior fusion and posterior laminoplasty operation. METHODS: 45 patients of cervical operation using CHA were followed up. Of these patients, 27 received anterior fusion and titanium plate fixation (34 levels fused). 18 with spinal stenosis at least at 3 levels, (posterior spinal process-splitting laminoplasty) had 79 split spinal processes fused by CHA. The average follow-up time was 25.9 months. RESULTS: The union rate of CHA was 85.3% in average by anterior approach. The height and angle of the fused level and the anterior salient were well maintained. The JOA score improvement rate was 58.7%. The CHA grafts were kept well between the split spinous processes with a union rate of 70.9%. After operation, the spinal cord moved dorsally, and the flat rate was improved from 0.19 to 0.41. No apparent posterior salient occurred. The JOA score improvement rate was 51%. CONCLUSION: The effect of CHA in cervical antero posterior operation is similar to that of autograft bone, and it is unnecessary to resect a piece of bone from a health region of the body.

Adult↗

PubMed2000

[Monitor visual function with flash visual evoked potential during orbital surgery].

OBJECTIVE: To evaluate the feasibility and reliability of monitoring visual function with flash visual evoked potential (FVEP) during orbital surgery. METHOD: The visual function of 82 cases was monitored during orbital surgery with FVEP. Of these cases, the intraoperative and postoperative visual functions (IOVF and POVF) were compared. RESULTS: Sixty-nine cases were successfully monitored. Sixty-seven cases obtained the accordance of IOVF and POVF, and there were false positive in 1 case and false negative in 1 case. CONCLUSION: Intraoperative monitoring of visual function with FVEP can show the surgical injury of the optic nerve and unsuitable procedures, and decrease the surgical blind rate.

Adolescent↗

PubMed2000

[FTIR study on the structures of bilirubin in solution].

The structures of bilirubin in solid-state, in HCCl3 and DMSO solution are investigated by FTIR spectroscopy. The results indicate that bilirubin have very different structures in solid-state and in solutions. The results also demonstrate that the structures vary in different solvents. There are six H-bonds in bilirubin molecule in solid-state, four in bilirubin molecule in HCCl3 solution and one in bilirubin molecule in DMSO solution.

Animals↗

PubMed1999

Outcomes among African-Americans and Caucasians in colon cancer adjuvant therapy trials: findings from the National Surgical Adjuvant Breast and Bowel Project.

BACKGROUND: African-Americans generally have lower survival rates from colon cancer than Caucasian Americans. This disparity has been attributed to many sources, including diagnosis at later disease stage and other unfavorable disease features, inadequate treatment, and socioeconomic factors. The randomized clinical trial setting ensures similarity in disease stage and a uniform treatment plan between blacks and whites. In this study, we evaluated survival and related end points for African-American and Caucasian patients with colon cancer participating in randomized clinical trials of the National Surgical Adjuvant Breast and Bowel Project (NSABP) to determine whether outcomes were less favorable for African-Americans. METHODS: The study included African-American (n = 663) or Caucasian (n = 5969) patients from five serially conducted, randomized clinical trials of the NSABP. We compared recurrence-free survival, disease-free survival (recurrence, new primary cancer, or death), and survival (death from any cause) between blacks and whites by using statistical modeling to account for differences in patient and disease characteristics between the groups. Statistical tests were two-sided. RESULTS: Dukes' stage and number of positive lymph nodes were remarkably similar between African-American and Caucasian patients in each trial. Over all trials combined, an 8% (95% confidence interval [CI] = -6% to 25%; P =.27) excess risk of colon cancer recurrence that was not statistically significant was observed for blacks. A greater disparity in survival was seen, with blacks experiencing a statistically significant 21% (95% CI = 6%-37%; P =.004) greater risk of death. Treatment efficacy appeared similar between the groups. CONCLUSIONS: While the overall survival prognosis was less favorable for African-Americans compared with Caucasians in these trials, other outcomes measured were considerably more similar than those seen in the population at large, suggesting that earlier detection and adjuvant therapy could appreciably improve colon cancer prognosis for African-Americans. Continued investigations into causes of the deficits noted are warranted.

Adult↗

PubMed1999

[Glutathione S-transferase GSTM1 and GSTT1 genotypes and susceptibility to lung cancer].

A 1:1 matched population-based case-control study was conducted in Xuanwei City, Yunnan Province, where the lung cancer mortality is among China's highest. In this study there were 86 newly diagnosed lung cancer cases and 86 matched control subjects with the same sex, fuel type used, and age(+/- 2 years). Buccal cells were collected from each subject to determine the genotypes of GSTM1 and GSTT1. It was found that the rate of GSTM1 null genotype was higher in the case group than in the control group, and its odds ratio was 2.39(95% CI: 1.25-4.56). The odds ratio became 2.62(95% CI: 1.33-5.15) when other possible confounding factors such as smoking, COPD, and the lifetime exposure to unvented fuel combustion (tons) were adjusted. No association was found between GSTT1 null genotype and lung cancer. The rate of GSTM1 null genotype in Xuanwei City was found to be similar to those of other Chinese populations.

Case-Control Studies↗

PubMed1999

Study on air pollution in Beijing's major industrial areas using multielements in biomonitors and NAA techniques.

Three kinds of plant leaves, Chinese white aspen, arborvitae, and pine needles, have been sampled from the Yanshan Oil refinery complex, the Capital Iron and Steel Factory, and Badachu, a control area in Beijing, as biomonitors for air-pollution studies. Each sample was divided into two parts, washed, and unwashed. Thirty-one trace elements (As, Au, Br, Ca, Cd, K, La, Lu, Mo, Na, Sb, Sm, U, W, Yb, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, Hg, Rb, Sc, Se, Sr, Ta, Tb, Th, and Zn) have been determined by using the relative and the K0 methods of instrumental neutron activation analysis (NAA) techniques. The results indicated the following: (1) The concentration of trace elements in unwashed samples are much higher than these in washed samples; (2) the area around Capital Iron and Steel Factory is heavily polluted, and the Yanshan Oil refinery complex area is moderately polluted; (3) Chinese white aspen is a good biomonitor in particular seasons and pine needles are better than arborvitae for yearly monitoring; (4) elements As, Cd, Hg, Co, Rb, Sb, W, and Zn are highly absorbed by Chinese white aspen. Pine needles are sensitive for the absorption the elements Br, Cr, Cd, Fe, Sc, Cs and rare earth elements, but arborvitae is very sensitive for the absorption of Sr.

Air Pollutants↗

PubMed1999

Preliminary study on the relationship between osteoporosis and trace elements with rat models.

Thirty rats were divided randomly into five groups and fed with different feeds. They were killed after 2 mo. Right thighs of these rats were taken as samples. Bone mineral densities of these samples were measured by the double-energy x-ray bone mineral densitometer, and trace elements contents of the samples were analyzed by neutron activation analysis. Results of the experiments showed that some elements were well correlated with others, and there were obvious variances between some elements of the normal group and those of other four groups.

Absorptiometry, Photon↗

PubMed1999

Factors influencing the levels of fatty acid synthase complex activity in fowl.

There is a notable discrepancy between the FAS (fatty acid synthase) activity of four types of fowl (egg chicken, meat chicken, egg duck, and meat duck) with distinctively different body fat levels. There is a 14.8 fold difference per unit body weight between the maximum and minimum FAS activities. The three major factors affecting this discrepancy are liver weight per unit body weight, which is 2.3 times greater in meat ducks than in egg chickens, the amount of FAS protein per gram of liver, which is 1.85 times greater in meat ducks than in egg chickens, and the FAS specific activity in meat ducks, which is 3.5 times greater in meat ducks than in egg chickens. Within the same species of egg chickens, the abdomen fat per kg of body weight at 470 days after egg production is 66 times greater than 90 days before egg production and the liver FAS activity is increased 9.6 fold. The 9.6 fold FAS activity increase resulted from an increase in the specific activity, since the liver weight per kilogram of body weight remained constant at approx. 20 grams and the FAS weight per gram of liver also remained constant at approx. 4.5 mg. This shows that the control of the basic FAS activity level which is closely related to the level of body fat does not mainly arise from genetic control. For the same kind of fowl, the control of the basic FAS activity level occurs after gene expression. It is suggested that control may be imposed in the folding phase when new peptides give rise to functional proteins.

Adipose Tissue↗

PubMed1999

Transcriptional control of development, protein synthesis, and heat-induced heat shock protein 70 synthesis in 2-cell bovine embryos.

Experiments were performed to evaluate the role of transcription in early development of bovine embryos. Two transcription inhibitors-5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) and actinomycin D-were used to test whether 1) the inhibitors alter the rate of early embryonic development and protein synthesis, 2) heat shock increases the steady-state amounts of mRNA for the inducible form of heat shock protein 70 (HSP70) in embryos, and 3) this latter effect is blocked by transcription inhibitors. Addition of either DRB or actinomycin D to culture medium beginning 8 h postinsemination (hpi) reduced the proportion of oocytes that had undergone cleavage by 32-34 hpi. Both transcription inhibitors also reduced the proportion of cleaved embryos that reached the 4-cell stage by 32-34 hpi. Incorporation of (35)S-labeled amino acids into de novo synthesized protein by bovine 2-cell embryos was lower for embryos cultured with DRB. Using reverse transcription-polymerase chain reaction, HSP70 mRNA in 2- and 4-cell embryos was increased by exposure to 42 degrees C. Both inhibitors reduced amounts of HSP70 mRNA at 42 degrees C. Results indicate that bovine embryos can undergo transcription in response to heat shock as early as the 2-cell stage. Moreover, the observations that transcription inhibitors reduce rates of cleavage and early development point out the importance of transcription for development from the earliest period of embryonic life.

Animals↗

PubMed1999

The Posterior Interosseous Nerve Anatomical Variation and Surgical Consideration - A Case Report of Cadaver Study.

We found an anatomical variation of the posterior interosseous nerve (PIN) in a cadaver. The PIN entered the supinator muscle 3 cm distal to the radiohumeral joint, but exited from two sites. 50% of the nerve exited under the distal edge of the supinator muscle. The other half of the nerve pierced through the supinator muscle, 4.2 cm distal to the articular surface of the radial head and then joined the remaining PIN as it emerged from the supinator muscle distally. We did not find variations concerning the order and the manner of branches to the muscles. This variation in the PIN could be an additional compression site for this nerve; and therefore responsible for some of the atypical presentations of symptoms and for partial recovery after surgical decompression. A careful surgical dissection should be recommended to avoid injury to this branch.

Journal Article↗