Biomedical subjects

Y Xiao

Publications and source records attributed to Y Xiao.

At least 127 records · Page 7Linked to original sources

PubMed2000

HIV-1 gp41 and type I interferon: sequence homology and biological as well as clinical implications.

HIV-1 gp41-like human type I interferon (IFN) could inhibit lymphocyte proliferation and up-modulate MHC class I and II and ICAM-1 molecule expression. Sequence comparison indicates that a similar epitope RILAV-YLKD exists between N-domain of gp41 and two regions in IFN-alpha(aa29-35 and 113-129), IFN-beta (aa31-37 and 125-138) and IFN-omega (aa29-35 and 123-136), which was shown to form IFN-alpha/beta-receptor binding site. Weak sequence similarity was also found to exist in both regions on gp41 and type I IFN of murine and bovine. Experimental studies indicated that a common immunological epitope exists between gp41 and IFN-alpha and -beta. Antibodies against human IFN-alpha and -beta recognized the common immunological epitope and inhibited gp41-binding to the potential cellular receptor protein p45. Moreover, the polyclonal antibody to IFN-beta completely inhibited gp41-binding to human T, B cells and monocytic cells, while IFN-alpha could only inhibit this binding incompletely. It was interestingly observed that human IFN-beta after preincubating with cells could incompletely inhibit the binding of gp41 to human B cells and monocytic cells, and very weakly inhibit the binding to human T cells, indicating that the receptor for IFN-beta-binding may be involved in gp41 binding. This potential relationship may be based on the amino acid sequence homology in the receptor binding region between gp41 and IFN-beta. It was observed that the increased levels of antibodies against human IFN-alpha and -beta exist in HIV-1-infected individuals and are associated with the common epitope on gp41. Besides, several studies provided experimental evidence that the common immunological epitope could induce protective activity against HIV-1. The IFN-alpha-based vaccine has showed a significant reduction of disease progression in IFN-alpha-vaccine-treated HIV-infected patients. Recent experimental evidence indicates that gp41 and IFN-beta were involved in downregulation of CCR5 expression and induction of cell activation or signal transduction. Whether it may be performed by a similar mechanism is still to be investigated.

Amino Acid Sequence↗

PubMed2000

A framework for epistemological analysis in empirical (laboratory and field) studies.

In their search for generalizable behavioral patterns and design principles, cognitive field researchers should reflect on the epistemological limitations of empirical studies. In this paper we describe a framework for epistemological analysis that can help serve this purpose and discuss its application to two prototypical cases of cognitive engineering research: laboratory experiments and field studies. The framework examines two, often implicit, processes in empirical research: the abstraction from empirical data and the substantiation of theoretical constructs and principles. By explicitly considering these two processes in several systematic steps, we can gain appreciation for the epistemological contribution of empirical studies to cognitive engineering research. The framework and its application also provide guidance to such important issues as generalizability of results and external validity. Possible applications of this research include providing guidance to researchers and practitioners in evaluating design principles or conducting field studies.

Cognitive Science↗

PubMed2000

Glycosaminoglycans in gingival crevicular fluid of patients with periodontal class II furcation involvement before and after guided tissue regeneration. A pilot study.

BACKGROUND: The levels of glycosaminoglycans in gingival crevicular fluid (GCF) are good indicators of underlying tissue turnover. We hypothesize that connective tissue elements in GCF may be used as indicators of tissue maturation underneath barrier membranes. Therefore, we investigated the levels of sulfated glycosaminoglycans in GCF at sites before and after guided tissue regeneration (GTR). METHODS: Six patients were selected on the basis of having at least one Class II buccal furcation involvement on a molar tooth. Each molar furcation was treated with the standard GTR surgical protocol using a non-resorbable expanded polytetrafluoroethylene membrane. Gingival crevicular fluid samples were taken at baseline (immediately prior to insertion of the membrane) and at 1, 2, 3, 4, 5, and 6 weeks (immediately prior to removal of the membrane). Glycosaminoglycan levels were determined using an Alcian blue dye detection system. RESULTS: The mean levels of chondroitin sulfate and total sulfated glycosaminoglycans in GCF significantly decreased during the first 4 weeks after GTR surgery. By week 5, the levels began to rise, and by week 6 the levels had returned to baseline levels. CONCLUSIONS: Sulfated glycosaminoglycans can be monitored in GCF at healing GTR sites. It is proposed that this is a useful means of monitoring the status of the regenerating tissues. However, further longitudinal studies are required to assess if the sulfated glycosaminoglycans can be used as indicators of tissue maturation under guided tissue membranes used to treat periodontal defects.

Adult↗

PubMed2000

Epitope-vaccine induces high levels of ELDKWA-epitope-specific neutralizing antibody.

Based on the fact that mAb 2F5 recognizing ELDKWA-epitope on the C-domain of HIV-1 gp41 has significant neutralization potency against 90% of the investigated viruses of African, Asian, American and European strains, we attempted to characterise immunogenicity of the ELDKWA-epitope on an epitope-vaccine, and to produce ELDKWA-epitope-specific monoclonal antibodies (mAb) induced by the epitope-vaccine. The C-domain peptide (P2) and the ELDKWA-tetramer peptide [C-(ELDKWAG)4] were conjugated with BSA or P24-EC (GPKEPFRDYVDRFYK, a peptide of HIV-1 gag-protein P24, proved to be a good carrier peptide to induce an immune response to the hapten on the conjugates[18])by different methods. After the vaccination course, two P2-BSA peptide-vaccines both induced a strong antibody response against the P2-peptide by about 1:12800-25600 dilution, and a weak antibody response against the ELDKWA-epitope (1:1600-3200). The P2-P24EC and P2 (conjugated with itself) peptide-vaccines could also induce a weak antibody response against the ELDKWA-epitope (1:1600-3200), while an rgp160 subunit vaccine induced a very weak antibody response (1:400). Interestingly, the ELDKWA-tetramer epitope-vaccine [C-(ELDKWAG)4-BSA] could induce a strong antibody response against the ELDKWA-epitope (1:12800-25600), i.e. It increased the level of ELDKWA-antibody eight-fold, clearly better than the P2 peptide-vaccine, and much better than the rgp160 subunit vaccine, which indicates that the immunogenicities of the ELDKWA-epitope on the ELDKWA-tetramer peptide, the C-domain peptide and rgp160 are very different. These results suggest that the ELDKWA-epitope-vaccine may be a new strategy for inducing high levels of epitope-specific neutralizing antibodies against HIV-1. Using hybridoma-technique, a mouse monoclonal antibody recognizing the ELDKWA-epitope on ELDKWA-peptide and C-domain peptide was produced by immunization with the C-(ELDKWAG)4-BSA epitope-vaccine, which indicates a new way to produce an epitope-specific mAb, namely immunization with epitope-vaccine instead of a natural or recombinant protein immunogen.

Amino Acid Sequence↗

PubMed2000

Cocaine induces apoptosis in fetal myocardial cells through a mitochondria-dependent pathway.

In the present study, we examined the direct cytotoxic effects of cocaine on fetal cardiac myocytes. Cocaine treatment of cultured fetal rat (21 days) myocardial cells (FRMCs) induced a time- and concentration-dependent increase in apoptotic cells in FRMCs. Cocaine induced surface exposure of phosphatidylserine in FRMCs at 12-h treatment and increased apoptotic cells up to 96 h. Corresponding DNA fragmentation induced by cocaine in these cells was demonstrated in situ by terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling assay and by electrophoresis of labeled DNA fragments, showing the characteristic apoptotic ladders. The pD(2) and maximum increase of cocaine-induced apoptosis in FRMCs were 4.3 and 3.2-fold, respectively. Both caspase-9 and caspase-3 inhibitors (Z-LEHD-FMK and Ac-DEVD-CHO, respectively) blocked cocaine-induced apoptosis. In addition, cyclosporin A inhibited cocaine-induced apoptosis in a concentration-dependent manner with an IC(50) value of 0.1 microM. The maximum of 86% inhibition was obtained with 3 microM cyclosporin A. Cocaine induced the release of cytochrome c from the mitochondria and increased its levels in the cytosol by 3.1-fold. In accordance, the level of cytochrome c in the mitochondria fraction decreased by approximately 60%. Cocaine-induced translocation of cytochrome c was inhibited by cyclosporin A. The results indicate that cocaine has a direct cytotoxic effect on fetal cardiomyocytes by inducing apoptosis in the cells. Furthermore, the release of cytochrome c from the mitochondria and its subsequent activation of caspase-9 and caspase-3 play a key role in cocaine-induced apoptosis.

Animals↗

PubMed2000

Dextromethorphan and its metabolite dextrorphan block alpha3beta4 neuronal nicotinic receptors.

Dextromethorphan (DM), a structural analog of morphine and codeine, has been widely used as a cough suppressant for more than 40 years. DM is not itself a potent analgesic, but it has been reported to enhance analgesia produced by morphine and nonsteroidal anti-inflammatory drugs. Although DM is considered to be nonaddictive, it has been reported to reduce morphine tolerance in rats and to be useful in helping addicted subjects to withdraw from heroin. Here we studied the effects of DM on neuronal nicotinic receptors stably expressed in human embryonic kidney cells. Studies were carried out to examine the effects of DM on nicotine-stimulated whole cell currents and nicotine-stimulated (86)Rb(+) efflux. We found that both DM and its metabolite dextrorphan block nicotinic receptor function in a noncompetitive but reversible manner, suggesting that both drugs block the receptor channel. Consistent with blockade of the receptor channel, neither drug competed for the nicotinic agonist binding sites labeled by [(3)H]epibatidine. Although DM is approximately 9-fold less potent than the widely used noncompetitive nicotinic antagonist mecamylamine in blocking nicotinic receptor function, the block by DM appears to reverse more slowly than that by mecamylamine. These data indicate that DM is a useful antagonist for studying nicotinic receptor function and suggest that it might prove to be a clinically useful neuronal nicotinic receptor antagonist, possibly helpful as an aid for helping people addicted to nicotine to refrain from smoking, as well as in other conditions where blockade of neuronal nicotinic receptors would be helpful.

Animals↗

PubMed2000

Regional variation in blindness in children due to microphthalmos, anophthalmos and coloboma.

BACKGROUND: The prevalence and causes of blindness in children vary widely between regions. Few epidemiological data are available on the relative importance of the major congenital anomalies of the globe (i.e., microphthalmos, anophthalmos, coloboma) as causes of blindness in children. The aim of this study was to determine the re-gional variation in the proportion of severe visual impairment and blindness due to congenital abnormalities of the globe in children in schools for the blind and in those identified through Community Based Rehabilitation programs. Other objectives were to estimate the prevalence of blindness due to major congenital abnormalities, and to investigate their etiology. METHODS: Data on the causes of blindness in children were collected between 1990 and 1998 using standard methods, definitions and reporting form in 26 countries. Children were examined in schools for the blind and in Community Based Rehabilitation programs. RESULTS: Of 7,113 children aged 3-15 years with severe visual impairment and blindness examined, 762 (10.7%) had microphthalmos, 161 (2.3%) had anophthalmos, and 96 (1.3%) had coloboma. There are large regional differences in the proportion of severe visual loss in blind school children, ranging from 1.4% in Cuba to 33.2% in Sri Lanka. Severe visual loss due to congenital abnormalities of the globe is estimated to affect between 0.4 and 16.2/100,000 children in the countries studied. An underlying cause could not be identified in 84.2%. CONCLUSIONS: Major congenital abnormalities of the globe are important causes of severe visual loss in children, particularly in Asian countries. Further research into etiology is warranted in order to plan prevention programs.

Adolescent↗

PubMed2000

Role of mitochondrial cytochrome c in cocaine-induced apoptosis in coronary artery endothelial cells.

Cocaine induces apoptosis in coronary artery endothelial cells. Yet the cellular and molecular mechanisms are not clear. Given that cocaine has profound toxic effects on the mitochondria, the present study examined the role of mitochondrial cytochrome c in cocaine-mediated apoptosis. Using cultured bovine coronary artery endothelial cells, we found that cocaine-induced apoptosis was dose dependently inhibited by cyclosporin A with IC(50) of 0.2 microM. The maximum of 65% inhibition was obtained with 3 microM cyclosporin A. Cocaine induced a translocation of cytochrome c from the mitochondria to the cytosol with a 1.8-fold increase in cytosolic cytochrome c levels, and a corresponding decrease in mitochondrial cytochrome c. In accordance with its inhibition of cocaine-induced apoptosis, cyclosporin A blocked cocaine-induced cytochrome c translocation. Correspondingly, cocaine-induced activation of caspase-9 preceded that of caspase-3. Caspase-8 was not activated. Cocaine also produced a dose-dependent decrease in Bcl-2 protein levels, but had no effect on Bax protein levels. The cocaine-induced decrease in the Bcl-2 protein was not affected by cyclosporin A but was partially blocked by caspase-3 inhibitor Ac-DEVD-CHO. Collectively, these data indicate that the release of cytochrome c from the mitochondria and the subsequent activation of caspase-9 and caspase-3 play a key role in cocaine-induced apoptosis in these cells. Furthermore, the down-regulation of the Bcl-2 protein may play an important role in cocaine-induced release of cytochrome c.

Animals↗

PubMed2000

[Automated analysis technology of electrocardiograms].

Study of detection and analysis methods for electrocardiograms(ECGs) has been developed for more a decade. But it is still existing some problems because of patient idiosyncrasy. The automated analysis of ECGs was simply summarized at the present for existing problems and with possible way to solve those troubles. We have reviewed preprocessing methods of waveform detection of ECGs and diagnosis techniques of arrhythmia.

Arrhythmias, Cardiac↗

PubMed2000

[Cloning and expression of full-length subtype E and subtype B gag gene from uncultured PBMCs of HIV-1 infected individuals in China].

OBJECTIVE: To clone and express subtype E and subtype B gag gene of the prevalent HIV-1 strain in China. METHODS: One HIV-1 positive sample, whose subtype had been determined as sub-type E and one HIV-1 positive sample, whose subtype had been determined as subtype B by sequence analysis of partial env gene were chosen to be amplified by nested PCR. We got two full-length fragments of gag gene and incorporated them first into plin8Pr55 and then into pFastBacl. RESULTS: Sequence analysis showed the cloned gag genes have the complete open-reading frames and have no major deletion and insertion. Using the Bac-toBac system, we obtained the recombinant baculoviruses containing gag genes. Western-blot analysis showed that insect cells infected with gag recombinant baculoviruses expressed HIV-1 gag antigen. Thin section electron microscopy showed that virus-like particles (VLPs) formed in insect cells was infected with gag. CONCLUSIONS: The cloning and expression of gag genes of the prevalent HIV-1 stains in China revealed that the cloned genes have intact structure and function and this paves the way for the development of HIV-1 vaccines targeted at the epidemic of HIV-1 in China, also for the study of biological functions of gag gene and development of diagnostic kits of HIV-1.

Animals↗

PubMed2000

[Significance of the changes of urinary uric acid, ANP, renin and aldosterone in sleep apnea syndrome patients].

OBJECTIVES: To assess the utility of urinary uric acid excretion and urinary uric acid/creatinine ratio as the marker of nocturnal respiratory disturbance in patient with sleep apnea syndrome (SAS) before and after the institution of nasal continuous positive airway pressure (nCPAP). Another purpose is to explore the relationship between the nocturnal diuresis and atrial natriuretic peptide (ANP), renin-aldosterone in SAS. METHODS: 22 cases diagnosed as SAS by polysomnography (PSG) were selected as trial group, 11 cases excluded from SAS by PSG were as control group, and 13 severe SAS patients were treated by nCPAP and taken as nCPAP therapy group. The markers mentioned above were compared in these groups. RESULTS: The overnight change in urinary uric acid/creatinine ratio in trial group is 0.47 +/- 0.31, which is significantly higher than that in control group (0.01 +/- 0.23), P < 0.05, and in nCPAP therapy group after therapy (0.01 +/- 0.19) significantly lower than that before nCPAP therapy (0.48 +/- 0.27), P < 0.001. The morning urinary uric acid excretion in trial group is (5.4 +/- 2.3) mg/L which is also significantly higher than that in control group (3.2 +/- 1.4) mg/L, P < 0.001, and in nCPAP therapy group (3.3 +/- 1.2) mg/L significantly lower than that before nCPAP (5.9 +/- 2.6) mg/L, P < 0.05. The mean morning blood ANP in trial group is (0.182 +/- 0.004) microgram/L, which is higher than that in control group (0.182 +/- 0.004) microgram/L, P < 0.05, and in nCPAP therapy group (0.122 +/- 0.001) microgram/L is much lower than that before nCPAP therapy (0.180 +/- 0.003) microgram/L, P < 0.001. However there are no statistic significant differences between these groups in blood renin-aldosterone. CONCLUSIONS: The urinary uric acid excretion and overnight change in urinary uric acid/creatinine are good markers to determine the effects of nCPAP on SAS. The nocturnal diuresis in SAS patients is correlated with the increase of ANP in plasma.

Adult↗

PubMed2000

Pancreatic insulinomas: experience in 220 patients.

OBJECTIVE: To summarize the experience in the diagnosis and treatment of insulinoma. METHODS: We retrospectively reviewed 220 patients with insulinoma confirmed surgically in the PUMC Hospital from 1953 to 1999. They were 131 men and 89 women, aged on average 39 years. RESULTS: In the 220 patients, the average interval from the onset of symptoms to diagnosis was 35 months. 54% of the patients were misdiagnosed before admission to the hospital. In 214 patients underwent operation, 201 (93.9%) had benign tumor and 12 (5.6%) malignant one. The diameter of 78% tumors was less than 2cm. 90.7% tumors were single and 9.3% were multiple. 37.1% tumors were located in the head and uncinate process of the pancreas, 26.1% in the body, 36.1% in the tail, and 0.7% ectopic. 95.5% patients had Whipple's triad and the ratio of insulin to glucose was greater than 0.3 in 89% patients. The positive rates of B-ultrasound, CT and MRI for localization before operation were low, but those of angiography and PTPC were 62.8% and 88% respectively. Most patients could be cured by simple enucleation of tumor. The main complications were pancreatic fistulae and pancreatitis. CONCLUSION: It is important for surgeons to familiarize with insulinoma, the most common islet cell tumor, for a better treatment.

Adult↗

PubMed2000

[Seven years' summary report on the treatment of acute promyelocytic leukemia with arsenic trioxide--an analysis of 242 cases].

OBJECTIVE: To observe the effectiveness of arsenic trioxide (As(2)O(3)) in the treatment of acute promyelocytic leukemia (APL). METHODS: Data of clinical observation, seven year follow-up survey were analysed with American SAS system software, concentration of arsenic in cerebrospinal fluid (CSF) was determined by atomic absorbing spectrum. RESULTS: The complete remission (CR) and effectiveness rates were 87.9% and 94.4% for the previously untreated group; 60.0% and 65.0% for the relapsed in As(2)O(3) maintenance treatment group; 69.5% and 84.8% for the relapsed in other than As(2)O(3) maintenance treatment group; and 48.7% and 94.1% for the refractory group, respectively. In the previously untreated group, the relapse rate at 3 years after CR was 26.7%. The probability of survival in 136 follow-up survey patients was 92.0% and 76.7% at 5 years and 7 years, respectively. There were mild side effects. Central nervous system leukemia (CNSL) occurred in 138 out of 412 cases in 6 years, including some refractory leukemia, extramedullary residual leukemia and extramedullary relapse. Prophylactic intrathecal injection could reduce the incidence rate of CNSL. Determination of arsenic concentration indicated that it was difficult for arsenic to penetrate the blood-brain barrier. CONCLUSION: The CR rate and long-term survival are high and the relapse rate is low in APL patients treated with As(2)O(3). There is no cross-resistance between ATRA and As(2)O(3) and other chemotherapeutic agents. As(2)O(3)-resistance occurs scarcely. It can also be used in maintenance treatment.

Adolescent↗

PubMed2000

[The effects of tea polyphenols on the adherence of cariogenic bacterium to the salivary acquired pellicle in vitro].

OBJECTIVE: It has been proved that tea polyphenols (TP) can inhibit the sucrose-dependent adherence of oral cariogenic bacterium to the tooth surface. This study is carried on to investigate the effects of tea polyphenols on the preliminary adherence of main cariogenic bacterium to salivary acquired pellicle and reveal the anticarious mechanisms of tea polyphenols further. METHODS: The hydroxyapatites were coated by saliva to form S-HA, an in-vitro model of experimental pellicle. Streptococcus mutans 3a3 and Actinomyces viscosus ATCC 19246 were chosen as the main cariogenic bacterium, and the microorganisms were radiolabelled by growing them in TPY culture medium supplemented with 3H-thymidine. Tea polyphenols solution was prepared, the concentrations of which were 0.5, 1.0, 2.0 and 4.0 mg/ml respectively. Two parts of inhibited adherence tests were done with TP-treated S-HA or TP-treated bacterium. In the first one, S-HA was immerged into the TP solution of different concentrations for 1 h before the attachment of bacterium. In the other, the bacterium were mixed with the TP solution for 1 h and then centrifuged and washed before bound to S-HA. The whole process was carried on in KCl buffer solution. The number of 3H-thymidine-labelled bacterium which attached to S-HA were determined by scintillation counting. RESULTS: In both the two parts of this study, tea polyphenols solution, the concentrations of which were changed from 1.0 to 4.0 mg/ml, could decrease the number of S. mutans 3a3 and A. viscosus ATCC 19246, and the inhibition rates rose with the increase of the concentrations of TP solution. But the inhibitory effects of 0.5 mg/ml TP solution were inconsistent in different tests. The results showed that 1.0-4.0 mg/ml TP solution could inhibit the attachments of S. mutans and A. viscosus to S-HA effectively. The inhibitory functions of tea polyphenols were so obvious that in some experiments, while the concentrations of TP solution were changed from 2.0 to 4.0 mg/ml, the number of 3H-thymidine-labelled bacterium which attached to S-HA was even less than that of the same bacterium which attached to naked HA. CONCLUSION: Tea polyphenols can inhibit the preliminary adherence of Streptococcus mutans and Actinomyces viscosus to S-HA effectively. TP may prevent enamel from caries by decreasing the adherence of main cariogenic bacterium to salivary acquired pellicle.

Actinomyces viscosus↗

PubMed2000

[The effects of tea polyphenols on the adherence of cariogenic bacterium to the collagen in vitro].

OBJECTIVE: In the first phase of our study, it has been proved that tea polyphenols (TP) can inhibit the preliminary adherence of oral cariogenic bacterium to salivary acquired pellicle. This study is carried on to investigate the effects of tea polyphenols on the preliminary adherence of main cariogenic bacterium to collagen I and reveal the anticarious mechanisms of tea polyphenols further. METHODS: Tea polyphenols solution was prepared firstly, the concentrations of which were 0.5, 1.0, 2.0 and 4.0 mg/ml. An in-vitro model of experimental pellicle(C-HA) was formed by immerging the hydroxyapatites in 250 micrograms/ml collagen I solution for 1 h. Streptococcus mutans 3a3, Actinomyces viscosus ATCC 19246 and Lactobacillus ATCC 4546 were chosen as the main cariogenic bacterium and radiolabelled by growing them in TPY culture medium supplemented with 3H-thymidine. Two parts of inhibited adherence tests were done with TP-treated C-HA or TP-treated bacterium respectively. In the first one, C-HA was immerged into the TP solution of different concentrations for 1 h before the attachment of bacterium. In the other, the bacterium were mixed with the TP solution for 1 h and then centrifuged and washed before bound to C-HA. KCl buffer solution provided a steady condition to the whole process. Finally, the number of 3H-thymidine-labelled bacterium which attached to C-HA were determined by scintillation counting. RESULTS: In both the two parts of this study, tea polyphenols solution, the concentrations of which were changed from 1.0 to 4.0 mg/ml could inhibit the attachments of S. mutans 3a3, A. viscosus ATCC 19246 and Lactobacillus ATCC 4546 to C-HA effectively, and the inhibition rates rose with the increase of the concentrations of TP solution. But the inhibitory effects of 0.5 mg/ml TP solution were inconsistent in different tests. The inhibitory functions of tea polyphenols were so prominent that in some experiments, while the concentrations of TP solution were higher than 2.0 mg/ml, the number of 3H-thymidine-labelled bacterium which attached to C-HA was even less than that of the same bacterium which attached to naked HA. These results showed that TP had the remarkable inhibitory efficiency on the attachments of S. mutans, A. viscosus and Lactobacillus to C-HA. CONCLUSION: Tea polyphenols can inhibit the preliminary adherence of Streptococcus mutans, Actinomyces viscosus and Lactobacillus to C-HA effectively. TP may prevent dentine from caries by decreasing the adherence of main cariogenic bacterium to collagen.

Actinomyces viscosus↗

PubMed2000

A comparison of the effects of two kinds of glass-ionomer cement on human gingival fibroblast attachment, proliferation and morphology in vitro.

The aim of this study was to compare the response of cultured human gingival fibroblasts to two kinds of glass-ionomer cement in vitro with regards to understanding the biocompatibility of these materials and their suitability for use as subgingival restorative materials. The glass-ionomer cements tested were Ketac Fil, and GC Fuji II. These cements were mixed according to the manufacturers' directions and condensed into tissue culture wells or cavities prepared on the root surfaces of extracted teeth. Healthy root slices and untreated tissue culture wells were used as controls. Several features such as attachment, proliferation and morphology of cells were studied. The results indicated that cells could not attach to the glass-ionomer cements unless they had been washed with distilled water and tissue culture media. No significant difference in initial attachment (1.5h) and long term attachment (48h) between the groups tested was noted. No significant difference was observed between levels of proliferation for human gingival fibroblasts grown on Ketac Fil, Fuji II, root slices and culture wells. No significant alterations of the cytomorphology could be detected in glass-ionomer cement compared with root slices. These results indicate that provided the surface is adequately washed, Ketac Fil, and Fuji II may be acceptable subgingival root surface restorative materials.

Analysis of Variance↗

PubMed2000

Polymorphism of angiotensin-converting enzyme gene and genetic susceptibility to asthma with familial aggregation.

OBJECTIVE: Angiotensin-converting enzyme (ACE) plays a key role in the metabolism of angiotensin II (AT II) and inactivation of bradykinins and tachykinins, which are potent bronchialconstrictors and mediators of inflammation asthma, and ACE is heavily expressed in the lungs. An insertion-deletion (D/I) polymorphism of ACE gene has been shown to be associated with levels of ACE. We investigate whether the polymorphism of ACE gene is associated with asthma and bronchial responsiveness. METHODS: A case-control study was carried out in 50 asthmatics, 7 families with at least 2 asthmatic individuals, and 50 healthy subjects. The insertion/deletion (I/D) polymorphism of ACE gene was amplified by polymerase chain reaction (PCR). Methacholine brocho-provocation and pulmonary function tests were performed in all asthmatics. RESULTS. There was an higher gene frequency of DD genotype of ACE gene in asthmatic subjects and families individuals compared with healthy subjects (46%, 53% vs 16%, P<0.05; odd ratio 4.98). An- higher prevalence of DD genotype of ACE was in patients with bronchial hyperresposiveness (BHR) (67% vs 33%, P<0.05; odd ratio 3.8). Accordingly, the mean values of FEV1% and FEV1/FVC were higher in asthmatics carrying non-DD alleles than patients with DD genotype (73.78% vs 56.56%, P<0.05, 79.19% vs 69.29%, P<0.05, respectively). CONCLUSION: These results suggested that DD allele of ACE genotype was significantly involved in genetic susceptibility to asthma. DD genotype of ACE might be a risk factor for the degree of airway obstruction, it could also be implicated in pathogenesis of bronchial hyperresponsiveness.

Adolescent↗

PubMed2000

Difference of rejection in single versus combined pancreas and kidney transplantation in rats.

OBJECTIVE: To investigate the difference of rejection in single versus combined pancreas and kidney transplantation in rats. METHODS: Allograft models including simultaneous pancreas and kidney (SPK) transplant and pancreas or kidney transplant alone were established in SD-Wistar rats, rejections of pancreas and kidney in different models were compared morphologically and functionally. RESULTS: Mean survival time (MST) of pancreas was significantly prolonged in SPK than in pancreas transplant alone (PTA) (11.5 days vs. 9.2 days, P < 0.05). Incidence of interstitial pancreatic rejection at gade II and grade III was much obvious in PTA than in SPK (42.9% vs. 12.5% at grade II and 28.6% vs 6.3% at grade II , P < 0.05). No significant difference was found in MST between SPK and kidney transplant alone( KTA). Administration of cyclosporine A prolonged the MST of pancreas and kidney, without altering the tendency stated above. CONCLUSIONS: In SPK, the function of pancreas is protected by kidney hence the severity of rejection is reduced, whereas the function of kidney is not protected by pancreas. It suggests that different organs differ in immunoallergization and immunoregulation, and immune response tend to attack organs with greater immunoactivity, those organs with minor one could be protected. Cyclosporine A is effective on prolonging the MST of pancreas and kidney.

Animals↗