Biomedical subjects

W Cai

Publications and source records attributed to W Cai.

At least 73 records · Page 4Linked to original sources

PubMed1998

High-resolution restriction maps of bacterial artificial chromosomes constructed by optical mapping.

Large insert clone libraries have been the primary resource used for the physical mapping of the human genome. Research directions in the genome community now are shifting direction from purely mapping to large-scale sequencing, which in turn, require new standards to be met by physical maps and large insert libraries. Bacterial artificial chromosome libraries offer enormous potential as the chosen substrate for both mapping and sequencing studies. Physical mapping, however, has come under some scrutiny as being "redundant" in the age of large-scale automated sequencing. We report the development and applications of nonelectrophoretic, optical approaches for high-resolution mapping of bacterial artificial chromosome that offer the potential to complement and thereby advance large-scale sequencing projects.

Chromosome Mapping↗

PubMed1998

Photolysis of phloxine B in water and aqueous solutions

Phloxine B (2',4',5',7'-tetrabromo-4,5,6,7-tetrachlorofluorescein disodium salt) as a potential photoactive insecticide was rapidly photodegraded in water under various light sources. Two major photolytic products characterized were 2',4',5'-tribromo-4,5,6, 7-tetrachlorofluorescein and 4',5'-dibromo-4,5,6, 7-tetrachlorofluorescein. The photolysis rates of phloxine B were influenced by various factors including salts in medium, sample pH, and light sources. Half-lives (t(1/2)) of phloxine B spiked in different water samples and 2% NaCl solution at 29 +/- 1 degreesC ranged from 0.70 to 1.28, 26.3 to 115, and 14.1 to 46.2 hours under 254 nm, 365 nm, and cool white fluorescent lights, respectively. Half-lives of phloxine B in tap, stream, or seawater in a beaker were from 10 to 13 min under sunlight at ambient air temperature. In a range of buffer pH 6-8 at 29 +/- 1 degreesC, phloxine B photodegraded slightly faster in acidic solution than in basic solution. The photolysis t(1/2) of phloxine B at 29 +/- 1 degreesC was 25, 32, 128, and 755 min in the buffered NaF, NaCl, NaBr, and NaI solutions, respectively. The t(1/2) of phloxine B was 31 min when phloxine B was dissolved in the sodium phosphate buffer as control. Sodium iodide and ammonium iodide photostabilized phloxine B 24 and 27 folds, respectively, when it was compared with the buffer control.

Journal Article↗

PubMed1998

Increased secretion of cholesteryl ester transfer protein from hamster adipose tissue: stimulation by beta-adrenergic agents.

High levels of cholesteryl ester transfer protein (CETP) favours decreased plasma high density lipoprotein cholesterol and increased levels of cholesterol in apolipoprotein B containing lipoproteins. Adipose tissue is one of the major sources of circulating CETP. Previous studies by our group and others demonstrated that the production of CETP from hamster adipose tissue increases after fasting, a metabolic state known to affect the sympathoadrenal axis. The present study examines the influence of beta-adrenergic agonists on the secretion of CETP from hamster adipose tissue. Fifteen minutes after an intraperitoneal injection of isoproterenol (12 microg/kg), the release of CETP mass and activity from adipose tissue fragments incubated in vitro were significantly increased. This was associated with an elevation in CETP mass and activity in plasma. The effects of isoproterenol on CETP release from adipose tissue and plasma CETP levels were suppressed by propranolol, a beta-adrenoceptor inhibitor. Addition of 10(-6) M isoproterenol to adipose tissue in vitro increased the release of CETP mass and activity from adipose tissue and this was also blocked by propranolol. Isoproterenol-induced secretion of CETP activity from adipose tissue was partially inhibited by cytochalasin B, an inhibitor of actin cytoskeleton reorganization. Forskolin, a classical adenylate cyclase agonist and 8-bromo-cAMP, a functional analogue of cAMP, mimicked the effect of isoproterenol on CETP release from adipose tissue. Our results suggest that isoproterenol increases the secretion of CETP from hamster adipose tissue through a beta-adrenoceptor and a cAMP-dependent pathway. Actin cytoskeleton reorganization may be required for secretion of CETP. The findings imply that the secretion of CETP from adipose tissue is under neurosympathetic control.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1998

Structural motifs in rheumatoid T-cell receptors.

The linkage of rheumatoid arthritis (RA) to HLA-DR haplotypes, high levels of HLA-DR expression, and T-cell infiltration in the joints, indicate a central role for the interaction of T-cell receptors (TCR) with antigen (Ag) + major histocompatibility complex (MHC) complexes in pathogenesis. Receptor analysis in RA has uncovered a restricted heterogeneity of TCR transcripts, suggesting an antigen-driven response. We analyzed the sequence and structural features of RA-associated TCRs in light of the recently published TCR crystal structures. The surface-exposed residues of the third complementarity-determining region (CDR3s) showed preferential use of certain amino acid residues when sequences derived from synovial fluid or tissue were compared with those derived from peripheral blood, particularly for alpha chains. Sequence alignment of oligoclonal synovial TCR CDR3s revealed groupings with similar CDR3 lengths and amino acid compositions, which suggests shared antigen recognition. Given the limitations of analyzing TCR sequences without knowing their structures, we developed several in vivo-activated synovial-tissue Vbeta17 + RA T-cell clones. Two Vbeta17/V alpha7 clones with different CDR3 sequences were analyzed by molecular modeling. Although distinct topologic features were seen, a central patch of residues with similar chemical and geometric characteristics was present in both. Electrostatic maps revealed similar binding surfaces of both alpha domains and central patches, with differences in the beta domains. This suggests that an alpha-domain-focused binding trajectory would allow shared antigen recognition by these TCRs. These studies support recognition of a limited diversity of Ag + MHC complexes by synovial RA TCRs.

Amino Acid Sequence↗

PubMed1998

Supraglottic carcinoma: does preoperative radiotherapy reduce the incidence of cervical metastasis?

OBJECTIVE: To compare surgery (S) alone with combined radiotherapy and surgery (R + S) in the management of patients with supraglottic laryngeal cancer. METHODS: Between 1981 and 1994, patients were stratified according to stage and randomised to either surgery (S) or 4000cGy of radiotherapy and surgery. There were 102 patients in the S group and 99 in the R + S group who completed at least 3-year follow-up. RESULTS: Using Kaplan-Meier survival method showed no significant difference between the two groups. When the patients were grouped according to tumour stage, a significant reduction in the regional recurrence was noted in the R + S group for stage I-III disease (Cox multivariate analysis, P < 0.02). They had an increased relative risk of 1.8 (95% confidence 1.1-2.9) for neck recurrence. There was no significant difference in neck recurrence rates in the two groups for stage IV disease. When Cox proportional hazard model was used, only TNM stage (P < 0.02) and histological nodal status (positive lymph nodes, P < 0.01) were found to be independent risk factors for regional control. CONCLUSION: Preoperative radiotherapy can improve regional cervical control of stage I-III supraglottic cancer as compared with surgery alone.

Adult↗

PubMed1998

[Establishment of a method for detecting transforming growth factor beta 1 mRNA].

AIM: To establish a method to measure the TGF-beta 1 mRNA level for studying the mechanism of fibrogenesis caused by schistosomiasis japonica. METHODS: Reverse-transcription polymerase chain reaction and dot blot analysis were used. A plasmid of TGF-beta 1 was constructed for standardization, and beta-actin was used as control. Eight different concentrations of the plasmid and 11 double-tube of TGF-beta 1 mRNA in the peripheral blood mononuclear cell (PBMC) of different persons were measured. RESULTS: Quantitative results of 8 different dilutions of TGF-beta 1 plasmid had positive with the logarithm of the original concentration. The results of the 11 double-tube were 1.71 +/- 0.90 and 1.54 +/- 0.88. CONCLUSION: The duplicability and stability of the method showed it can be used to analyse the TGF-beta 1 mRNA level of the peripheral blood mononuclear cells.

Humans↗

PubMed1997

Pravastatin increases survival and inhibits natural killer cell enhancement factor in liver transplanted rats.

Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, has been shown to decrease the number of acute rejection episodes in cardiac and renal transplant patients. This study evaluates the effects of pravastatin on survival of rats following liver transplant and attempts to elucidate the mechanisms of these effects. Both survival and natural killer cell enhancing factor (NKEF) studies utilized Dark Agouti rats for donor livers transplanted into Brown Norway rats as recipients. All rats received daily low-dose cyclosporine (CsA) 2 mg/kg/day by gavage. The treated groups also received gavage doses of pravastatin, 20 mg/kg/day. Survival data were analyzed by the method of Kaplan-Meier and log-rank chi 2 tests for statistical significance. For NKEF evaluation, rats were sacrificed at varying time points; total RNA was extracted from the liver and hybridized with 32P-radiolabeled NKEF DNA probes in the Northern blot technique. Radiographs were quantitated using densitometry. Data were analyzed by two-way ANOVA. Actuarial survival was improved (P < < 0.05) in rats treated with pravastatin in addition to low-dose CsA (n = 41, CsA alone n = 74). Less fibrosis and chronic rejection was seen on histological section in the treated animal livers, P < 0.05, NKEF was seen maximally at Days 5-15 tapering off at Day 21. NKEF-a and NKEF-b levels were significantly decreased in the animals treated with CsA and pravastatin compared to CsA alone in the group of animals < 16 days postop (P < < 0.05). Pravastatin improves survival in rats following OLT and while the mechanism is still unknown, inhibition of natural killer cell enhancement factor may represent an alteration in the overall immune response.

Animals↗

PubMed1997

Adrenal proteins bound by a reactive intermediate of mitotane.

PURPOSE: Mitotane (o,p'-DDD), is the only adrenolytic agent available for the treatment of adrenocortical carcinoma. Previous studies have shown that mitotane covalently binds to adrenal proteins following its metabolism in adrenocortical tissue to a reactive acyl chloride intermediate. It was the objective of this study to compare the electrophoresis separation patterns of such adducts following activation of mitotane by various adrenocortical sources. METHODS: With the use of a 125I-labeled analog of mitotane, 1-(2-chlorophenyl)-1-(4-iodophenyl)-2,2-dichloroethane, gel electrophoresis patterns were obtained for homogenates from bovine, canine and human adrenocortical preparations as well as from a human adrenal preparation. Western immunoblotting analysis was used to test the resulting patterns for adducts of cytochrome P-450scc and adrenodoxin. RESULTS: The electrophoresis separations were similar for all preparations, with bands at apparent molecular weights of 49.5 and 11.5 kDa being the most pronounced. Radiolabeling of the proteins of a human adrenal cancer cell line NCI H-295 was weak, but a band at 11.5 kDa was detected. Western immunoblotting analyses indicated that the band at 49.5 kDa corresponded in molecular weight to that of adrenal cytochrome P-450scc, but the band at 11.5 kDa did not correspond to adrenodoxin. CONCLUSIONS: The similarity of the results with canine and bovine adrenal preparations to that of human material offers useful systems for studying mitotane and its analogs. This should aid in understanding the mechanism of action of mitotane and in the design of compounds for the treatment of adrenocortical carcinoma.

Adrenal Cortex↗

PubMed1997

The role of Fas/APO 1 and apoptosis in the development of human atherosclerotic lesions.

The possibility that Fas/APO 1 is involved in the apoptosis of advanced human coronary atherosclerosis was examined in the present study. Coronary arteries with atherosclerosis were obtained from human hearts with chronic ischemic heart disease at cardiac transplantation. Normal vessels were used as controls. Fas/APO 1 was detected by immunohistochemistry with a monoclonal antibody. Apoptotic cells were stained in situ by terminal deoxynucleotidyl transferase mediated-dUTP nick end labeling (TUNEL) and DNA fragmentation into oligonucleosomes was checked by gel electrophoresis. Bcl-2, an antiapoptotic oncoprotein, was detected by immunohistochemistry and Western blot. Apoptotic cells were present in the neointima in all stages of atherosclerosis, and in intraplaque small vessels. In initial lesions, only a few cells were undergoing apoptosis. By contrast, in advanced lesions, many cells were found to undergo apoptosis. Apoptosis was further confirmed by genomic DNA analysis using gel electrophoresis. Apoptotic cells were either smooth muscle cells or macrophages, but also endothelial and blood borne cells. Fas/APO 1 was present in foam cells. Most of the Fas/APO 1 positive cells were stained for the macrophage marker CD68 and for alpha-smooth muscle actin in serial sections. Several anti-Fas/APO 1 positive foam cells were revealed to undergo apoptosis by double staining. Bcl-2 was detected in Fas/APO 1 expressing plaques. A number of CD3-positive T-lymphocytes were found around foam cells expressing Fas/APO 1. This data suggests that Fas/APO 1 regulated apoptosis is involved in the development of advanced human atherosclerotic lesions and that it probably determines the amount of tissue mass in the diseased vessels.

Antibodies, Monoclonal↗

PubMed1997

Differential structuring of human populations for homologous X and Y microsatellite loci.

The global pattern of variation at the homologous microsatellite loci DYS413 (Yq11) and DXS8174 and DXS8175 (Xp22) was analyzed by examination of 30 world populations from four continents, accounting for more than 1,100 chromosomes per locus. The data showed discordant patterns of among- and within-population gene diversity for the Y-linked and the X-linked microsatellites. For the Y-linked polymorphism, all groups of populations displayed high FST values (the correlation between random haplotypes within subpopulations, relative to haplotypes of the total population) and showed a general trend for the haplotypes to cluster in a population-specific way. This was especially true for sub-Saharan African populations. The data also indicated that a large fraction of the variation among populations was due to the accumulation of new variants associated with the radiation process. Europeans exhibited the highest level of within-population haplotype diversity, whereas sub-Saharan Africans showed the lowest. In contrast, data for the two X-linked polymorphisms were concordant in showing lower FST values, as compared with those for DYS413, but higher within-population variances, for African versus non-African populations. Whereas the results for the X-linked loci agreed with a model of greater antiquity for the African populations, those for DYS413 showed a confounding pattern that is apparently at odds with such a model. Possible factors involved in this differential structuring for homologous X and Y microsatellite polymorphisms are discussed.

Female↗

PubMed1997

Effect of hypoxia on blood glucose, hormones, and insulin receptor functions in newborn calves.

At between 7 and 11 h after delivery, 14 fasted calves were randomly divided into two groups to examine the effects of neonatal hypoxia on blood glucose metabolism and its mechanisms. One group was subjected to breathe a gas mixture containing 4.8-5.9% oxygen in nitrogen from a hood for 2 h. The second control group breathed atmospheric gas. Several possible causes of changes in blood glucose were assessed, including insulin, glucagon, and hydrocortisone as prereceptor factors, insulin binding as a receptor factor, and insulin receptor tyrosine kinase (IR-TK) activity as a postbinding factor. The hypoxic animals exhibited increased concentrations of blood glucose (from 5.47 +/- 1.61 mmol/L to 7.97 +/- 1.30 mmol/L), plasma insulin, and hydrocortisone, but decreased concentrations of glucagon. The percentage of specific binding activity decreased in the hypoxic group compared with the control group (12.71 +/- 1.25% versus 15.14 +/- 1.27%, p < 0.01). Several parameters of insulin receptor binding, i.e. affinity constants, high and low binding capacities, and numbers of binding sites, showed a tendency to decrease after hypoxia. Only lower affinity binding sites decreased significantly. At the postreceptor level, IR-TK activity was decreased in the hypoxic group compared with controls. It is concluded that hypoxia induced insulin resistance in these newborn calves. The results suggest that the primary mechanism for insulin resistance in the hypoxic newborn was reduced insulin receptor responsiveness with attenuated activity of IR-TK at the postreceptor level.

Acid-Base Equilibrium↗

PubMed1997

[Long-term survival of fetal substantia nigra grafts in striatum of PD rats: an observation of tyrosine hydroxylase immunohistochemistry and western blot].

By using immunohistochemistry and Western blot, we observed the varied patterns of survival, development and growth of dopaminergic neurons after intrastriatal transplantation of fetal substantia nigra. There was a phenomenon of "developmental delay" of grafts in the host. As the time of transplantation went on, the grafted dopaminergic neurons could reinnervate the host neurons. The observation reveals that the reinnervation between graft and host is more beneficial to the functioning of the grafts.

Animals↗

PubMed1997

[Intraparenchymal and intraventricular transplantation of fetal substantia nigra cell suspension in rat model of Parkinson's disease].

The grafts of fetal substantia cell suspension grafts could bring into a behavioral effect and characteristics of histology and immunocytochemistry in rat models of PD after the grafts were transplanted either into the lateral ventricles or directly into the striatum. It was found that the intraparenchymal tromsplantation of fetal nigral cell suspensions not only was beneficial to reinnervation between host and grafts, but also produced more complete and steady effects than the intraventricular transplantation. We concluded that the restoration of nervous functional deficits of PD rats is likely to depend on both extensive dopaminergic reinnervation throughout the grafted sites and on closer integration of the grafts with the host striatal circuitry.

Animals↗

PubMed1997

[Purification, serology and detection of grapevine leaf roll virus].

Closterovirus-like particles associated with grapevine leaf roll disease were purified from stem phloem tissue by differential centrifugation and cesium sulphate-sucrose density gradient centrifugation. The particles were between 660-2000 nm long. Most of them were about 1400 nm long and also decorated by the antiserum against GLRV NY-1 isolate. The purified preparation was tested for their serological relatedness in indirect ELISA. The results indicated that these closterovirus-like particles reacted with serotype II, III and IV of GLRV. The antiserum to NY-1 (type III) reacted more strongly than type IV (to VA-4) and type II. (to 1800 nm). In sodium dodecyl sulfate immunodiffusion test, the extract of diseased petiole reacted with serotype III, IV and II. It is possible to be infected by 2 or 3 closterovirus-like particles in China. We have made antiserum to the purified closterovirus-like GLRV and set up a PAS-ELISA to detect GLRV-free grapevine plantelets. We have obtaimed 21 varieties of GLRV-free and GFLV-free grapevine. They shown high quality and quantity in field test.

English Abstract↗

PubMed1997

[Recombinant AAV-LMP-induced LMP specific cytotoxic response to autologous lymphoblastoid cell lines tranformed by Epstein-Barr virus].

Epstein-Barr virus is believed to be controlled in normal host by virus specific cytotoxic T lymphocytes (CTL). Although unable to eliminate EBV from the body, CTL seems to be essential in control of latently infected cells. Infusion of autologous EBV specific CTL, which can be produced in laboratory by separating lymphocytes from patients and stimulating them with EBV antigen, will provide an effective method of preventing and treating EBV-related diseases. We inserted the LMP gene of EB virus into an AAV vector pACP and packed it in Ad2 infected 293 cells by co-transfecting with plasmid Ad8, which produced the recombinant virus rAAV-LMP. The recombinant virus was used to infect stimulating cells and LMP antigen was expressed on the surface of these cells. Then the stimulating cells were irradiated and co-cultured with T lymphocytes. The EBV specific CTLs were obtained. The target cells were autologous LCLs from EBV-transformed B lymphocytes. The CTL activity was assayed by BLT activity method. The result indicated that all the four CTL strains could recognize and kill their target cells. This study has laid the technical basis for us to prevent and treat nasopharyngeal carcinoma in China with molecular biological methods.

Cell Line↗

PubMed1997

Direct bladder stimulation with suture electrodes promotes voiding in a spinal animal model: a technical report.

To determine the efficacy of a new electrode for direct bladder stimulation, five male cats were instrumented during anesthesia. Multistranded, 316LVM, stainless-steel, wire electrodes were implanted on the bladder wall serosa above the trigone area. The electrodes were made with a needle attached to the end that was cut off after suturing the electrode in place. Additional instrumentation included tubes for pressure recording and filling, and hook electrodes for leg and pelvic floor EMG recording. Bladder filling and stimulation studies were conducted in tethered animals 1 to 2 weeks following recovery. Chronic studies were conducted following recovery in tethered animals. To test these electrodes in a spinal cord injury (SCI) model, a T-1 level complete lesion was performed on the above instrumented animals. Spinal animals had successful direct bladder stimulation that induced active contractions and voiding both before and after SCI, but voiding rates were higher more than 2 weeks after SCI and at larger initial bladder volumes. Optimum stimulation parameters consisted of 40 pulses per second, 300 microseconds to 1 ms pulse duration, a stimulation period of 3 to 4 s, and 10 to 40 mA. Urethral resistance, indicated by a urethral function measure, showed that stimulation had no adverse effect on urethral function, and fluoroscopy showed an open membranous urethra during stimulation and voiding. The cat has a small penile urethra that is the flow rate controlling zone. The suture electrode did not corrode, erode into the bladder, or become dislodged, and appears suitable for chronic implantation.

Animals↗

PubMed1997

Expression of proliferating cell nuclear antigen in Wilms' tumor.

OBJECTIVE: To investigate the expression of proliferating cell nuclear antigen (PCNA) and its clinical significance in Wilms' tumor. METHODS: PCNA immunoreactivity on paraffin-embedded tissues was assessed retrospectively in 35 cases using labelled streptaridin biotin (LSAB) procedure, and its association with clinical and other biological features was studied. RESULTS: Twelve tumors (34.29%) expressed PCNA. Expression rate increased with the advance of stage (P < 0.05). The S-phase fraction and proliferation index (PI) in children with PCNA positive expression were higher than those in children with negative PCNA expression (P < 0.05). The survival rate (16.67%) in patients with positive PCNA expression was significantly lower than that (73.91%) in no-expression ones (P < 0.01). CONCLUSION: PCNA is a sensitive indicator for cell proliferation and is clinically useful in identifying a poor prognostic group of patients with Wilms' tumor.

Child↗

PubMed1997

Changes of ultrasonography and two serum biochemical indices for hepatic fibrosis in schistosomiasis japonica patients one year after praziquantel treatment.

OBJECTIVE: To observe the changes of abdominal sonography and 2 biochemical indicators for hepatic fibrosis before and after treatment with praziquantel in schistosomiasis japonica patients. METHODS: Fifty-five persons infected with Schistosoma japonicum and treated with praziquantel were examined with ultrasonography and serum hyaluronic acid (HA) and type III procollagen (PC III) before and 1 year after treatment, and their data were compared with those in 55 normal controls. RESULTS: With comparison of the data before praziquantel treatment, the length of the left liver lobe and the spleen in 55 patients all decreased (P < 0.01) 1 year after treatment. No significant change was seen in interior diameter (d) of the portal vein, while a decrease in the ratio of the exterior diameter (D) and interior diameter of the second branch of the portal vein was very significant (P < 0.01). Compared with the data in normal control, significantly higher levels in the thickness of the left lobe, the maximum oblique diameter of the right lobe, the length of the spleen, spleen index, the interior diameter of the portal vein and D/d ratio were seen in the patients both before and after treatment. The abnormal rate of the 2 serum parameters for hepatic fibrosis decreased significantly after treatment. CONCLUSIONS: Parameters of hepatic fibrosis either by ultrasonography or by the 2 biochemical tests showed a significant improvement in 55 patients 1 year after treatment, although some of the indices did not yet return to normal levels.

Adolescent↗