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Biomedical subjects

L Wang

Publications and source records attributed to L Wang.

At least 379 records · Page 21Linked to original sources
PubMed2001

The role of prostaglandins in the antiarrhythmic effect of ischemic preconditioning.

The role of prostaglandins in the antiarrhythmic effect of ischemic preconditioning (IP) was investigated in pentobarbital-anesthetized rats. In 5 unpreconditioned control rats, 30 min of occlusion of the left coronary artery elicited ventricular tachycardia (VT) and fibrillation (VF), with an average duration of VT and VF of 51 +/- 6 and 43 +/- 4 s, respectively. Frequent ventricular premature beats (VPBs; average 1,249 +/- 145) were also documented in these animals. Thirty minutes of reperfusion after the prolonged coronary occlusion in these animals caused more severe arrhythmias, including irreversible VF. In animals pretreated with IP (n = 5), which was achieved by 3 cycles of 3 min of occlusion followed by 5 min of reperfusion, 30 min of coronary artery occlusion caused neither VT nor VF, but occasional VPBs (average 2 +/- 1, p < 0.001 vs. control). Only occasional VPBs were observed during 30 min of reperfusion in this group. In animals pretreated with indomethacin (1 mg/kg i.v., n = 5) followed by IP, prolonged ischemia and reperfusion led to frequent VPBs but no VT or VF. The average number of VPBs during ischemia and reperfusion in this indomethacin-treated group was less than that of the controls but greater than the IP-only group (p < 0.01). In conclusion, prostaglandins appear to play a role in the protective effect of IP against VPBs during acute ischemia and reperfusion.

Animals↗
PubMed2001

Study on apoptosis and expression of P53, bcl-2, Bax in cardiac myocytys of congestive heart failure induced by ventricular pacing.

The apoptosis and the expression of p53, bcl-2 and Bax in myocytes of chronic rapid ventricular pacing-induced congestive heart failure (CHF) in rabbits were investigated. The CHF rabbit model (P, n = 7) was established by chronic rapid ventricular pacing for 3 weeks. By using TUNEL technique the apoptosis in the myocytes in the rabbit model was studied and the expression of p53, bcl-2 and Bax in myocytes was detected by using immunohistochemical method. Sham-operated (C, n = 9) group served as control group. The results showed that there were about 4033 +/- 884.56 apoptotic cells/10(6) myocytes in P group, but no apoptotic cells were found in C group. Myocytes positive for p53 immunoreactivity (18.86 +/- 8.48 vs 5.06 +/- 0.87, P < 0.01) and positive for Bax immunoreactivity (7.15 +/- 1.91 vs 0.43 +/- 0.09, P < 0.01) were increased in P group as compared with those in C group, while the myocytes positive for bcl-2 immunoreactivity (7.08 +/- 1.05 vs 14.97 +/- 4.47, P < 0.01) and the ratio of bcl-2/Bax were decreased in P group as compared with those in C group. Apoptosis was involved in the development of CHF induced by continuously rapid ventricular pacing in rabbit. The expression of p53 and Bax was increased, while the expression of bcl-2 was inhibited. These might play an important role in the acceleration of the apoptosis.

Animals↗
PubMed2001

Short-coupled variant of torsade de pointes.

Presented in this paper were 3 cases of a special kind of polymorphic ventricular tachycardia (VT). The clinical manifestation was recurrent syncope without organic heart disease. The electrocardiogram (ECG) was characterized by normal QT intervals with short-coupled variant of torsade de pointes. The efficacy of treatment with class I, II, III antiarrhythmic drugs was not apparent but verapamil had an excellent therapeutic effect for it. This kind of VT had a high incidence of sudden death, so it was very important for physicians to identify and treat it promptly with long-term verapamil. The mechanism of short-coupled variant of torsade de pointes was unclear. It probably had some relationship with triggered activity or imbalance of autonomic nervous system.

Adult↗
PubMed2001

Separate and combined effects of growth hormone and parathyroid hormone on cortical bone osteopenia in ovariectomized aged rats.

The focus of this study is on whether cortical osteopenia occurs in ovariectomized aged female rats, and if so, whether growth hormone (GH) and parathyroid hormone (PTH) independently or together (GH+PTH) can rebuild the lost cortical bone. Tibio-fibula junction was analyzed by histomorphometry and peripheral quantitative computerized tomography (pQCT) densitometry. Significant loss of cortical bone area (Ct. BAr), cortical bone mineral content (Ct. BMC), cortical thickness (Ct. Th) and increase of endocortical perimeter occurred 4 months after ovariectomy. The rats were given GH, PTH, GH+PTH or vehicle for 2 months and sacrificed. GH, PTH and GH+PTH increased Ct. BAr, Ct. BMC, Ct. Th, periosteal perimeter, periosteal double-labeled perimeter, mineral apposition rate, and bone formation rate, but decreased marrow area. PTH and GH+PTH decreased endocortical perimeter, and increased endocortical double labeled perimeter and bone formation rate. In conclusion, ovariectomy induced cortical bone loss in aged rats by increasing endocortical bone resorption. Growth hormone increased periosteal bone formation, while PTH stimulated endocortical bone formation and in combination GH+PTH produced complementary effects thereby reversing osteopenia.

Aging↗
PubMed2001

Mouse histamine N-methyltransferase: cDNA cloning, expression, gene cloning and chromosomal localization.

OBJECTIVE: Histamine N-methyltransferase (HNMT) catalyzes the Ntau-methylation of histamine. We set out to clone a mouse liver HNMT cDNA and the mouse HNMT gene as steps toward characterizing molecular genetic mechanisms involved in the regulation of this important histamine-metabolizing enzyme. DESIGN: A PCR-based strategy was used to clone both the mouse HNMT cDNA and the gene encoding that cDNA, Hnmt. The cDNA was used both to express recombinant mouse HNMT and to determine the chromosomal localization of Hnmt. RESULTS: The mouse liver HNMT cDNA was 1657 bp in length with an 888 bp open reading frame (ORF) that encoded a 296 amino acid protein with a predicted Mr value of approximately 32.5 kDa. The amino acid sequence of the encoded protein was 84% identical to that of human kidney HNMT. Mouse HNMT was expressed in COS-1 cells, and its apparent Km values for histamine and S-adenosyl-L-methionine (Ado-Met), the two cosubstrates for the reaction, were 5.3 and 5.8 microM, respectively. The mouse HNMT gene, Hnmt, spanned approximately 25 kb and had 7 exons. Its structure differed from that of the human gene primarily by the presence of an additional exon at the 5'-terminus. Hnmt mapped to mouse chromosome 2 in an area of conserved synteny to human chromosome 2q, the location of the human gene (2q22) on the basis of fluorescence in situ hybridization. CONCLUSIONS: Cloning and functional characterization of the mouse HNMT cDNA and gene will now make it possible to study in the mouse molecular genetic mechanisms involved the regulation of this important histamine-metabolizing enzyme.

Amino Acid Sequence↗
PubMed2001

Detection of complement C1-inhibitor with a piezoelectric immunosensor.

A novel piezoelectric immunosensor has been developed for the detection of human complement C1-inhibitor. Anti-C1-inhibitor antibody was immobilized onto the gold electrodes of a 9 MHz AT-cut piezoelectric crystal. Coating the crystal with polyethyleneimine adhesion, followed by a glutaraldehyde cross-linking method to immobilize antibody showed better results than the physical adsorption method with respect to sensitivity and reproducibility. Under the optimized experimental conditions, the sensor showed good response to the C1-inhibitor in the range from 2.0 x 10(-8) to 1.2 x 10(-6) g. Other proteins in human serum did not remarkably interfere with the detection. The crystals could be regenerated 5 times, when bound materials on the crystal surface were eluted by strong acid and strong alkali solution and subsequently cleaned in an ultrasonic cleaner.

Biosensing Techniques↗
PubMed2001

In-situ separation of the matrix for the direct determination of traces of chromium, cobalt, and nickel in titanium dioxide powder by electrothermal atomic-absorption spectrometry with slurry sampling.

A novel method has been developed for the direct determination of traces of chromium, cobalt, and nickel in TiO2 powder; it entails slurry sampling and electrothermal atomic-absorption spectrometry (ETAAS) with a polytetrafluoroethylene (PTFE) slurry (6% m/v) as fluorinating reagent. The factors which could affect the vaporization of the matrix and analytes were studied in detail; the fluorinating vaporization behavior of the analyte both in the slurry and in solution were also investigated. Owing to the in-situ separation of the matrix, the matrix influences were reduced significantly. The proposed method has been applied to the direct determination of traces of chromium, cobalt, and nickel in high-purity TiO2 powder without chemical pretreatment. Under the optimum experimental conditions the detection limits of the analytes (Cr, Co, and Ni) were 1.9 ng g(-1), 2.4 ng g(-1) and 5.4 ng g(-1), respectively, the relative standard deviations (RSD) were 3.4% (n=6, c=7.0 ng mL(-1)), 2.9% (n=6, c=0.70 ng mL(-1)), and 7.6% (n=6, c=4.0 ng mL(-1)), again respectively, and the characteristic masses for Cr, Co, and Ni were 8.4 pg/ 0.0044A, 9.3 pg/0.0044A, and 40.0 pg/0.0044A, respectively.

Alloys↗
PubMed2001

Development of the fragment constant method for estimating the partition coefficients of nonionic organic mixtures.

The fragment constant model for estimating partition coefficient of nonionic organic mixtures is developed based on group contribution theory. For 60 mixtures randomly composed of eight substituted benzenes, the C(18)-Empore disks/water partition coefficients (K(MD)) are determined. Establishment of a model between these K(MD) and the mole fraction of the fragments (Cl, Br, I, NO(2), CH(3)) acquires the fragments constants for K(MD). The significant linear regression equation, between these fragment constants and that of Hansch, provides an approach for calculating K(MD) of untested nonionic organic mixtures by using the fragment constants of Hansch.

Benzene↗
PubMed2001

Florid reactive periostitis and bizarre parosteal osteochondromatous proliferation: pre-biopsy imaging evolution, treatment and outcome.

OBJECTIVE: To report on the imaging evolution of florid reactive periostitis (FRP) and bizarre parosteal osteochondromatous proliferation (BPOP) of the phalanges of the hands from prospective diagnosis to operation and on postsurgical outcome. DESIGN AND PATIENTS: Three patients (2 female, 1 male; age range 11-34 years) presented with a swollen digit of the hand. Following presumptive radiographic diagnosis of FRP, they were closely observed both clinically and radiographically until operation. All three patients had radiographs of the involved digit, and one patient had an MR imaging examination. The interval between presumptive diagnosis and operation ranged from 2 to 8 months. Following operation, the patients have been clinically followed for 9-13 months (mean 10 months). RESULTS: In each of the patients, maturing of periosteal reaction without bone destruction was observed within 1-2 weeks of the presumptive diagnosis of FRP. Periosteal reaction was initially minimal in relation to the extent of soft tissue swelling and subsequently became more florid. In one patient, the lesion ossified, became adherent to the phalanx, and had an "osteochondromatous" appearance. In another patient, periosteal reaction was seen on both sides of the phalanx with an intact phalanx. In the sole patient who had MR imaging, edema was seen in the phalanx distal to the symptomatic site and the metacarpal proximal to the symptomatic site. CONCLUSIONS: Close clinical and radiographic correlation permits an accurate pre-biopsy diagnosis of FRP. The first follow-up radiograph taken within 2 weeks usually provides re-assurance of the accuracy of the diagnosis. FRP may progress to BPOP. Arbitrary antibiotic treatment can be avoided, and a planned surgical approach can be adopted.

Adult↗
PubMed2001

Impacts of urbanization on stream habitat and fish across multiple spatial scales.

We analyzed the relation of the amount and spatial pattern of land cover with stream fish communities, in-stream habitat, and baseflow in 47 small southeastern Wisconsin, USA, watersheds encompassing a gradient of predominantly agricultural to predominantly urban land uses. The amount of connected impervious surface in the watershed was the best measure of urbanization for predicting fish density, species richness, diversity, and index of biotic integrity (IBI) score; bank erosion; and base flow. However, connected imperviousness was not significantly correlated with overall habitat quality for fish. Nonlinear models were developed using quantile regression to predict the maximum possible number of fish species, IBI score, and base flow for a given level of imperviousness. At watershed connected imperviousness levels less than about 8%, all three variables could have high values, whereas at connected imperviousness levels greater than 12% their values were inevitably low. Connected imperviousness levels between 8 and 12% represented a threshold region where minor changes in urbanization could result in major changes in stream condition. In a spatial analysis, connected imperviousness within a 50-m buffer along the stream or within a 1.6-km radius upstream of the sampling site had more influence on stream fish and base flow than did comparable amounts of imperviousness further away. Our results suggest that urban development that minimizes amount of connected impervious surface and establishes undeveloped buffer areas along streams should have less impact than conventional types of development.

Agriculture↗
PubMed2001

Mechanisms of transcriptional repression by the t(8;21)-, t(12;21)-, and inv(16)-encoded fusion proteins.

AML-1 is one of the most frequently translocated genes in human leukemia. AML-1 binds DNA and activates or represses transcription, while the chromosomal translocation fusion proteins in acute myeloid leukemia subvert these functions. The t(8;21) is the second most frequent translocation in acute myeloid leukemia and creates a fusion between the DNA binding domain of AML-1 and the ETO (also known as MTG8) corepressor. The t(12;21) is found in up to 25% of pediatric B cell acute lymphoblastic leukemias and fuses the ETS family transcription factor TEL to the amino terminus of AML-1. In addition, the inv(16), the most frequent translocation in acute myeloid leukemia, fuses the AML-1 cofactor CBFbeta to the smooth muscle myosin heavy chain MYH11. Both the t(8;21) and t(12;21) create transcriptional repressors that impair AML-1 target gene expression. We demonstrated that the fusion proteins encoded by these translocations contact the nuclear hormone corepressors (N-CoR/SMRT), mSin3A, and histone deacetylases. We have also found that both TEL and AML-1 interact with mSin3A. TEL also binds N-CoR and histone deacetylase-3, indicating that wild-type TEL is a transcriptional repressor. The t(12;21) fuses the mSin3A interaction domain of TEL to AML-1 to transform AML-1 from a regulated to an unregulated transcriptional repressor. The recognition that AML-1 interacts with mSin3A to repress transcription suggested that the inv(16) fusion protein might also repress the transcription of AML-1-target genes. In fact, the inv(16) encodes a protein that cooperates with AML-1 to repress transcription. The inv(16) fusion protein was found in a ternary complex with AML-1 and mSin3A, suggesting that the inv(16) also acts by recruiting transcriptional corepressors and histone deacetylases.

3T3 Cells↗
PubMed2001

[Morphological evaluation of posterior capsule opacification in diffractive multifocal intraocular lenses].

BACKGROUND: Diffractive multifocals belong to the first generation of multifocal intraocular lenses. Dure to their optical principle of diffraction multifocals separate the incoming light on two foci (41%) with 18% loss of scattered light. Therefore, reduced contrast sensitivity and glare have been frequently described with this lens. PATIENTS AND METHODS: We evaluated 42 eyes of 25 patients (age at surgery 63.8 +/- 8.8 years) 3 years after implantation of a Pharmacia 811E diffractive multifocal (MIOL). They were tested for functional results including contrast and glare (Mesoptometer II). In addition 22 eyes were evaluated for posterior capsule opacification (PCO) using digitalized retroilluminations photographs and the EPCP image analysis program. RESULTS: Average visual acuity was 0.77 +/- 0.20 (uncorrected distance), 0.93 +/- 0.21 (corrected distance), 0.94 +/- 0.13 uncorrected near) und 0.98 +/- 0.08 (best corrected near). PCO-values quantified by EPCO were 1.13 +/- 0.59 (Range 0.07 to 2.1). On average 18.1 +/- 14.9% of the optic area showed an opacification grade 1, 35.8 +/- 26.6% grade 2 and 7.7 +/- 17.1% grade 3. Contrast sensitivity showed no patient with contrast level 7 or better for monocular evaluation, but 30% for binocular testing. Only 4% met the criteria for night driving when tested for glare. Spearman correlation did not reveal any significant correlation between PCO-values and visual acuity, contrast sensitivity or glare (all p > 0.24, all r < 0.22). CONCLUSIONS: Patients with diffractive multifocal IOLs showed excellent results for near and distance visual acuity three years after implantation. However, contrast and glare results were poor, probably due to a rather high PCO-rate. Future developments of the lens type should include PCO-reducing factors, such as sharp edge optics and foldable materials.

Aged↗
PubMed2001

T1 hypointensity of the spinal cord in multiple sclerosis.

It has recently been shown in multiple sclerosis (MS) that the volume of T1 hypointense lesions in the brain explains more of the variance in disability amongst patients than T2 lesion volume. T1 hypointense lesions may therefore represent areas of underlying pathology likely to be of functional significance, such as axonal loss. The spinal cord is a common area of involvement in MS and its dysfunction is likely to be responsible for much of the motor disability seen. Hence it serves as a useful model by which to examine the functional relevance of differing imaging sequences. We have therefore examined the relationship between T1 signal intensity in the spinal cord and disability in 60 patients with MS. We have also examined the relationship between T1 signal intensity and atrophy of the cord, as the latter is another potential marker of axonal loss. Sixty patients with MS underwent spinal cord imaging with a T1 weighted sequence to acquire axial sections of the cord at the C2 level. These sections were histogram matched to allow comparison of image intensity and a manual outlining technique was applied from which the mean cord intensity was calculated. Within the patient group there was a significant relationship between T1 signal intensity and disability as measured with the EDSS (r = -0.4, p < 0.005) and also between T1 signal intensity and atrophy (r = 0.36, p < 0.005). This study demonstrates that disability and atrophy are associated with a generalised reduction in cord signal on T1 weighted images. A lower T1 signal intensity in the spinal cord may be more pathologically specific than T2 hyperintensity and may represent underlying axonal loss, although gliosis and predominant white matter atrophy are alternative possibilities.

Adult↗
PubMed2001

Characterization, physical location and expression of the genes encoding calcium/calmodulin-dependent protein kinases in maize (Zea mays L.).

The maize genomic sequence and cDNA encoding a calcium/calmodulin-dependent protein kinase homolog were isolated and identified. The deduced peptide (MCK2) from this cDNA shared high amino acid identity (91.2%) with maize MCK1. These two genes were physically mapped onto chromosomes by fluorescence in situ hybridization using the first introns of the genes as gene-specific probes. While the MCK1 gene was assigned to a locus on the long arm of chromosome 9, the MCK2 gene was localized to a locus on the long arm of chromosome 1. Both of these genes were expressed in roots, leaves, stems and flowers, and the expression patterns of MCK were verified by RNA in situ hybridization. These results indicated that MCK expression is temporally and spatially regulated during maize growth and development.

Amino Acid Sequence↗
PubMed2001

Short-term folic acid supplementation induces variable and paradoxical changes in plasma homocyst(e)ine concentrations.

Folic acid is presently the mainstay of treatment for most subjects with elevated plasma homocyst(e)ine concentrations [Plasma or serum homocyst(e)ine, or total homocysteine, refers to the sum of the sulfhydryl amino acid homocysteine and the homocysteinyl moieties of the disulfides homocystine and homocystein-cysteine, whether free or bound to plasma proteins.] Changes in homocyst(e)ine in response to folic acid supplementation are characterized by considerable interindividual variation. The purpose of this study was to identify factors that contribute to heterogeneity in short-term responses to folic acid supplementation. The effects of folic acid supplementation (1 or 2 mg per day) for 3 wk on plasma homocyst(e)ine concentrations were assessed in 304 men and women. Overall, folic acid supplementation increased mean plasma folate 31.5 +/- 98.0 nmol/L and decreased mean plasma homocyst(e)ine concentrations 1.2 +/- 2.4 micromol/L. There was evidence of substantial interindividual variation in the homocyst(e)ine response from -18.5 to +7.1 micromol/L, including an increase in homocyst(e)ine in 20% of subjects (mean increase 1.5 +/- 1.4 micromol/L). Basal homocyst(e)ine, age, male gender, cigarette smoking, use of multivitamins, methylene tetrahydrofolate reductase, and cystathionine beta-synthase polymorphisms accounted for 47.6% of the interindividual variability in the change in homocyst(e)ine after folic acid supplementation, but about 50% of variability in response to folic acid was not explained by the variables we studied.

Aged↗
PubMed2001

Results of surgical resection of patients with primary lung cancer: a retrospective analysis of 1,905 cases.

BACKGROUND: Surgical resection, combined therapies, and lymphadenectomy are extensively utilized in the treatment of patients with lung cancer. In the present study, we summarized the clinical data of patients with primary lung cancer after surgical resection alone or combined with adjuvant therapy, and evaluate the main factors influencing long-term survival. METHODS: A retrospective review of 1,905 consecutive patients with primary lung cancer treated at the Cancer Institute of the Chinese Academy of Medical Sciences from March 1961 through December 1995 was performed. Statistical analysis was done using STATA software. The survival rate was estimated using the life-table method. Survival differences were performed using the log-rank test. The modified 1997 TNM staging system was used. RESULTS: There was a 12.28% morbidity rate and a 1.31% hospital mortality in our series. The 5-year survival rate for the complete resection was 49.5% and for the palliative resection 18.8% (p < 0.01). The 5-year survival rate was 72.0% in stage IA and 61.0% in stage IB (p < 0.05), 32.9% in stage IIA and 34.5% in stage IIB, 22.6% in stage IIIA and 15.9% in stage IIIB (p < 0.05), and 7.1% in stage IV. CONCLUSIONS: Multiple factors influence the long-term survival of patients with primary lung cancer after surgery. They include TNM staging, the extent of surgical resection (complete or palliative), resection margin (positive or negative), pathologic type of tumors, and type of resection.

Adult↗