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Biomedical subjects

Z Gao

Publications and source records attributed to Z Gao.

At least 91 records · Page 5Linked to original sources
PubMed1999

Seroprevalence of cytotoxin-associated gene A positive Helicobacter pylori strains in Changle, an area with very high prevalence of gastric cancer in south China.

BACKGROUND: Helicobacter pylori, especially the CagA-positive strains, are closely associated with peptic ulcers and gastric cancers. We performed a large scale gastric cancer screening project and examined the prevalence of H. pylori and CagA-positive strains in Changle, China, an area with one of the World's highest gastric cancer mortality. We also compared the prevalence with that in Hong Kong which has one-tenth of the gastric cancer mortality of that in Changle. METHODS: A total of 2424 subjects in Changle and 523 subjects in Hong Kong had endoscopic examination and venesection. Sera were tested for anti-H. pylori antibody and anti-CagA antibody and correlated with endoscopic findings. RESULTS: In Changle, 80. 9% of the subjects were H. pylori carriers. Out of 551 carriers, 408 (74%) were positive for anti-CagA antibody. A total of 76% and 87% of the asymptomatic and gastric cancer patients were positive for anti-CagA antibody, respectively (P > 0.05). Compared to Hong Kong, there was a significantly (P < 0.0001) higher prevalence of CagA-positive strains in asymptomatic subjects in Changle (76%) than in Hong Kong (28%), but not in peptic ulcers or gastric cancers. CONCLUSIONS: Subjects in Changle had a high prevalence of H. pylori infection and a high prevalence of the CagA-positive strains. The contrast in the prevalence of CagA-positive strains, in asymptomatic subjects in two areas with differing gastric cancer mortality, supports the pathogenic role of CagA-positive strains in gastric carcinogenesis.

Adolescent↗
PubMed1999

Differential Helicobacter pylori infection rates in two contrasting gastric cancer risk regions of South China. China Gastric Cancer Study Group.

BACKGROUND: Carriers of Helicobacter pylori are believed to have a three- to six-fold increased risk of developing gastric cancer. We have recently conducted a simultaneous cross-sectional population study on the prevalence of H. pylori infection in a cohort of asymptomatic adult volunteers in two contrasting gastric cancer risk regions of South China, Hong Kong and Changle of Fujian. Their mean annual gastric cancer mortality has been approximately 7.5 and 75/100 000 population, respectively, since the beginning of the last decade. The aim of this study was to evaluate if H. pylori prevalence bears any relationship to gastric cancer mortality rates in these two southern regions of China. METHODS: Sera were obtained from 397 volunteers in Hong Kong. They were tested for anti-H.pylori immunoglobulin (Ig) G antibody by using a commercial enzyme-linked immunosorbent assay (ELISA) kit. Volunteers of Changle (1456) had upper endoscopy examination and were also tested for anti-H. pylori IgG antibody by the same ELISA method. RESULTS: The overall H. pylori infection prevalence was significantly higher in Changle (80.4%) than in Hong Kong (58.4%; P< 0.01). The high prevalence is associated with more atrophic gastritis. The overall risk of gastric cancer in people of Changle is approximately five-fold that of Hong Kong (adjusted odds ratio 4.9, 95% CI 2.5-9.8). CONCLUSIONS: It is concluded that the prevalence of H. pylori infection rates bear a direct relationship to gastric cancer mortality rates in these two southern regions of China. Thus, H. pylori most likely plays a significant aetiopathogenetic role in gastric carcinogenesis in subjects living in Changle.

Adult↗
PubMed1999

Different effects of the constituents of EGb761 on apoptosis in rat cerebellar granule cells induced by hydroxyl radicals.

The present study was conducted to evaluate the different effects of the constituents of EGb761 (Ginkgo biloba Extract) on apoptosis in cerebellar granule cells induced by hydroxyl radicals. The total flavonoid component of EGb761, two pure EGb761 components (rutin and quercetin), and a mixture of flavonoids and terpenes protected cerebellar granule cells from oxidative damage and apoptosis induced by hydroxyl radicals. ESR(electron spin resonance) results showed that the IC50 of the flavonoids for scavenging hydroxyl radicals was almost the same as that of EGb761, even though flavonoids make up only 24% of EGb761, implying that other constituents of EGb761 besides flavonoids can scavenge hydroxyl radicals. Total terpenes of EGb761 did not protect against apoptosis. Flavonoids and terpenes did not show a synergistic effect in this regard. Terpenes did not scavenge hydroxyl radicals directly, which might be related to their "cage-like" structures.

Animals↗
PubMed1999

Dynamic behavior of the Ziff-Gulari-Barshad model on fractal lattices: the influence of the order of ramification.

A catalytic reaction model, the Ziff-Gulari-Barshad model, is studied on fractal lattices, and the influence of the order of ramification of the lattice on the dynamic behavior of the model is investigated. According to the Monte Carlo simulation results, the order of ramification of the lattice is not crucial to the existence of the continuous transition. This is different from the equilibrium phase transitions in discrete-symmetry spin models (such as the Ising model). Our results indicate that the criterion of the existence of the reactive phase may be complicated.

Journal Article↗
PubMed1999

A novel alkaline alpha-galactosidase from melon fruit with a substrate preference for raffinose

The cucurbits translocate the galactosyl-sucrose oligosaccharides raffinose and stachyose, therefore, alpha-galactosidase (alpha-D-galactoside galactohydrolase, EC 3.2.1.22) is expected to function as the initial enzyme of photoassimilate catabolism. However, the previously described alkaline alpha-galactosidase is specific for the tetrasaccharide stachyose, leaving raffinose catabolism in these tissues as an enigma. In this paper we report the partial purification and characterization of three alpha-galactosidases, including a novel alkaline alpha-galactosidase (form I) from melon (Cucumis melo) fruit tissue. The form I enzyme showed preferred activity with raffinose and significant activity with stachyose. Other unique characteristics of this enzyme, such as weak product inhibition by galactose (in contrast to the other alpha-galactosidases, which show stronger product inhibition), also impart physiological significance. Using raffinose and stachyose as substrates in the assays, the activities of the three alpha-galactosidases (alkaline form I, alkaline form II, and the acid form) were measured at different stages of fruit development. The form I enzyme activity increased during the early stages of ovary development and fruit set, in contrast to the other alpha-galactosidase enzymes, both of which declined in activity during this period. In the mature, sucrose-accumulating mesocarp, the alkaline form I enzyme was the major alpha-galactosidase present. We also observed hydrolysis of raffinose at alkaline conditions in enzyme extracts from other cucurbit sink tissues, as well as from young Coleus blumei leaves. Our results suggest different physiological roles for the alpha-galactosidase forms in the developing cucurbit fruit, and show that the newly discovered enzyme plays a physiologically significant role in photoassimilate partitioning in cucurbit sink tissue.

Journal Article↗
PubMed1999

Adoptively transferable tolerance induced by CD45RB monoclonal antibody.

The phenomenon of rejection remains the most serious problem in transplantation. The ultimate goal in transplant immunology is to develop therapeutic strategies that lead to tolerance. It has been shown that two injections of a monoclonal antibody to CD45RB leads to indefinite acceptance of renal allografts in mice. Moreover, the CD45RB monoclonal antibody reverses acute rejection and still induces tolerance. The purpose of this study was to assess mechanisms that could underlie this therapeutic benefit. It was shown that splenic lymphocytes from tolerant animals augmented proliferation in allogeneic mixed lymphocyte reactions against donor alloantigens, and the serum of tolerant mice contained donor-specific antibodies, mainly of the IgG1 isotype, suggesting the presence of TH2 cytokines. Tolerance could not be broken by interleukin-2 infusion, but tolerance could be adoptively transferred by transfusion of tolerant mouse CD4+ splenic lymphocytes into naive allografted animals. These data suggest that an active immunoregulatory mechanism is partly responsible for the therapeutic effect. CD45RB-directed therapy may find clinical application in organ transplantation in human patients.

Adoptive Transfer↗
PubMed1999

Recent advances in neurokinin receptor antagonists.

The structurally related neuropeptides, substance P (SP), neurokinin A (NKA), and neurokinin B (NKB), which belong to a family of molecules termed tachykinins and are widely distributed in the central and peripheral nervous systems, influence the function of many tissues. SP and NKA have links to the following chronic diseases: asthma, inflammatory bowel disorders, rheumatoid arthritis, pain and psychiatric disorders. These peptides exert their effects through three G-protein coupled receptor subtypes, namely, the NK1, NK2, and NK3 receptors. Non-peptide antagonists of these receptors may provide opportunities for disease treatments. In this review, the very recent advances in nonpeptide neurokinin receptor antagonists will be described with an emphasis on structure-activity relationships which have been developed.

Amino Acid Sequence↗
PubMed1999

[Inhibitory effect of triplex forming oligodeoxynucleotides on HBV replication and synthesis of antigen].

OBJECTIVE: To explore the inhibitory effect of triplex forming oligodeoxynucleotides(TFO) on replication of HBV and synthesis of antigen. METHODS: A 21 mer phosphorothioate triplex forming oligodeoxynucleotides (TFO21) directed at SP1 sites in HBV core promoter and a control of 21 mer phosphorothioate oligodeoxynucleotides (ODNcon) were synthesized. HepG 2.2.15 cells which can produce HBsAg, HBeAg, HBV DNA and HBV particle were treated with TFO21 and ODNcon. In HepG 2.2.15 cells treated with these oligodeoxynucleotides, the levels of HBsAg, HBeAg, and HBV DNA were examined by ELISA and dot hybridization method, respectively. RESULTS: The levels of HBsAg, HBeAg and HBV DNA in TFO21 group were lower than those in the bank control group. At concentration of 10 mumol/L, TFO21 inhibited synthesis of HBsAg and HBeAg by 57.5% and 77%. The inhibitory effect of TFO21 was dosage-dependent, and was related to time in which 2.2.15 cells were incubated with TFO21. No inhibition was observed in the ODNcon group. No toxicity was observed in the 2.2.15 cells treated with oligodeoxynucleotides. CONCLUSION: These results indicate that TFO is a potent inhibitor for HBV replication and synthesis of antigen, and also suggest that TFO is a therapeutic potential for the treatment of patients infected with HBV.

DNA, Viral↗
PubMed1999

ATP sensitive potassium channel and myocardial preconditioning.

KATP channels play an important role in physiology and pathophysiology of many tissues. As in the pancreatic beta cells, they couple the change of blood glucose with insulin release. The data coming from Baukrowitz et al. and Shyng and Nichols gave the possible answers to the two old enigmas of KATP channels, i.e., different ATP sensitivity reported in the same tissue and how the channel opened under intracellular millimolar ATP concentration, in which they showed the lipids and lipid metabolites are essential for KATP channel regulation by altering ATP sensitivity. This new information rises several further considerations. How does PIP2 reduce the sensitivity of the channel to ATP? In order to clarify the possibility of direct competing or allosteric effect on the ATP binding site, competitive binding assay should be performed. Since the PIP2 theory seems to be the key event to determine the ATP sensitivity and thus control the channel open probability, then what is the resting concentration of PIP2 in the cell membrane? Is it sufficient to account for the difference in the ATP sensitivity of the intact cell and excised patch from different tissues? Quantitative studies either immunoblotting by PIP2 antibody or fluorescence-labeled lipid assay-may obtain some basic but useful data for further studies to answer these questions. Furthermore, the ATPi mediated restoration of activity was inhibited by antibodies against PIP2. The dualistic behavior of KATP channels to intracellular NDPs should be reexamined with respect to PIP2. The vast majority of preconditioning studies has been performed in intact animals in which myocardial infarct size was used as the end point to define the cardio-protective effect of ischemic PC. These results suggest a key role for the KATP channel as both a trigger and as an end effector of both acute and delayed ischemic PC. The persistent activation of KATP channels during the early reperfusion phase is essential for a smooth and full recovery of contractile function, as well as for maintenance of electrical stability in heart that has been exposed to ischemia. Though activate adenosine A1 receptor coupled with Gi protein can open the KATP channels, adenosine is quickly released during ischemia and exerts potent coronary vasodilatation to maintain coronary blood flow through A2 receptors. This adenosine-induced coronary vasodilatation could be coupled with KATP channels based on the evidence of the augmentation effect of KCOs. Nitric oxide may also play some role in both first and second window of myocardial protection. It is possible that rapid and reversible phosphorylation and activation of constitutive expressed myocardial NOS or by direct KATP channel phosphorylation and activation leads to the first window of myocardial protection. This hypothesis can be further investigated either by using site direct mutagenesis of iNOS or KATP channel, or by applying the dominant negative iNOS in the cell ischemic model, or by building the adenosine or iNOS knock-out mice to study the relationship of these possible mechanisms. Recently, Kontos further showed that KCOs need L-lysine or L-arginine to dilate cerebral arterioles. This suggests that there may be an amino acid binding site inside the KATP channel and nitric oxide can open the KATP channel either by direct acting on the channel protein or by modulating the affinity of the amino acid binding site for L-lysine or L-arginine. Other KATP channel openers in need of additional characterization are the Type III KCOs (nicorandiol). They open the KATP channel only in the presence of elevated intracellular NDPs, which may make them specifically target to the ischemic region, because the intracellular NDP increases mostly in ischemic region. It is possible that type III KCOs can selectively improve blood flow to ischemic areas without diverting blood away to non-ischemic region, and prevents the "steal phenomenon". (ABSTRACT TRUNCATED)

Adenosine Triphosphate↗
PubMed1999

[Pylorus-preserving pancreatoduodenectomy--a report of 15 cases].

OBJECTIVE: To prevent post operative disturbauce of gastric emptying by pylorus-preserving pancreatoduodenectomy (PPPD). METHODS: 1. To preserve the vascular and nerve supply of gastric antrum, pylorus and duodenal bulb during operation. 2. To ensure long enough resection of duodenum from the pylorus. 3. To perform folding suture to shorten the hapatogastric ligament. RESULTS: In 15 cases of pancreatic and periampullar cancer so freated, neither residual cancer nor gastric emptying disorder was found after operation. The quality of life of the patients was improved. CONCLUSION: PPPD is a therapeutic choice for patients with pancreatic and peri-ampullar cancer.

Adult↗
PubMed1999

[Experimental study on anti-cancer effect of Cantharidine derivatives and platinum complex].

OBJECTIVE: To certify the anti-tumor effects of the four Cantharidine derivatives and platinum complex on transplanted tumor in mice to search for new anti-tumor drugs. METHODS: Complex of four Cantharidine derivatives (Dpt 1-15, Dpt 5-10, Dpt 12-3 and Dpt6-2) and platinum were given to tumor beating mice of transplanted S180 sarcoma, H22 solid hepatocarcinoma and ascites hepatocarcinoma through intraperitoneal or intravenous injection, and the effect of treatment on tumor weight and survival of animal were observed. Cisplatin was used as positive control and 0.9% normal saline used as negative control. All data were treated with t test. RESULTS: All the four complex had anti-tumor effect. The inhibition rate of Dpt5-10 and Dpt1-15 on S180 sarcoma and H22 solid hepatocarcinoma and the survival prolongation rate of Dpt5-10 on H22 ascites hepatocarcinoma were similar to those of cisplatin. The toxicity of effective dose of Dpt1-15 was rather high. CONCLUSIONS: Cantharidine derivatives and platinum complex is new effective anti-tumor drug, among them the Dpt5-10 is the most effective one. Further study for improving the solubility of drug is necessary and study the difference of cross resistance between the new complex and cisplatinum.

Animals↗
PubMed1999

[Atypical intrathoracic sarcoidosis: a report of 21 cases].

OBJECTIVE: To improve the recognition of atypical intrathoracic sarcoidosis. METHODS: The clinical data of 21 cases with atypical intrathoracic sarcoidosis were analyzed retrospectively. All the cases had pathological examination data. RESULTS: The manifestations of atypical intrathoracic sarcoidosis might be as follows: intrapulmonary pathological changes including solitary nodular shadow, atelectasis, unilateral lung consolidation, bilateral lung consolidation and bilateral pulmonary miliary nodes; simple mediastinal lymph node lesion including mediastinal tumor, mediastinal lymph node enlargement plus unilateral pulmonary hilar lymph node enlargement and simple mediastinal lymph node enlargement; pleural lesion including hydropneumothorax and pleural thickening; pulmonary hilar lesion including unilateral pulmonary hilar lymph node enlargement plus mediastinal lymph node enlargement and bilateral pulmonary hilar lymph node enlargement and calcification. CONCLUSION: The clinical manifestations of atypical intrathoracic sarcoidosis are variable. The establishment of the diagnosis cannot be based on image examination alone. With sufficient knowledge of the clinical manifestations of sarcoidosis and other testing methods, the diagnosis can be made correctly.

Adolescent↗
PubMed1999

[Low-molecular-weight chromium-binding substances in hepatic and nephric tissues of chromium-exposed rats].

Male Wistar rats were injected intraperitoneally with potassium dichromate(2.55 mg Cr6+ per kg body weight) for 7 days, and were observed continuously for 7 days after stopping Cr injection. The results were that concentrations of chromium-binding substances (HMW-Cr, LMW-Cr, and MMW-Cr) increased significantly with the extension of Cr injection time; MMW-Cr was not found in the control group. MMW-Cr may be a valuable indicator in diagnosing chromium toxication. It was efficient to use Sephadex G-50 column chromatography and ultra-violet absorption spectrometry-atomic absorption spectrophotometry in isolation, and then it was followed by quantitative analysis of chromium-binding substances.

Animals↗
PubMed1999

[The clinical application of scalp expansion in the repair of cicatricial baldness in children].

OBJECTIVE: To introduce the clinical application of the expanded graft from scalp in the repair of cicatricial baldness in children. METHODS: 45 cases with baldness following burn from 1988 to 1998 were reported. All of these patients (age ranged from 5-11 years) were treated by soft tissue expander. RESULTS: 5 cases were followed up for 1-2 years, the clinical results showed that the result from the graft of scalp expansion was satisfactory, and the long-term follow-up revealed that the hair in expended area and that in normal area was almost the same except the orientation of hair distribution had some difference. CONCLUSION: The head scalp expansion might be the first choice in the repair of cicatricial baldness following burn.

Adolescent↗
PubMed1999

[Surgical reduction and rigid internal fixation of midface fractures].

OBJECTIVE: To determine the cause, clinical characteristics and treatment of midface fractures. METHODS: A retrospective review of 98 patient records was conducted. Data regarding age, cause of fracture, anatomic site, treatment modalities and clinical results were reviewed. RESULTS: Of the 98 patients, 78.6% were male, with the peak incidence occurring in the age group from 21 to 40 years old. Of the fractures, 32.6% were due to traffic accidents, 24.5% to assaults, and 17.3% to accidental falls. Most patients (87.8%) were treated by open reduction surgery and rigid internal fixation. Only 12.2% of patients were treated by closed reduction fixation. Almost all of the patients regained normal face appearance and functional occlusion. CONCLUSION: Surgical reduction and rigid internal fixation of midface fractures is a satisfactory method of treatment.

Adolescent↗
PubMed1999

Pilot study of schistosomiasis control in Poyang lake region.

AIM: To perform a longitudinal survey of the control of schistosomiasis in Fanhu Village hyperendemic for schistosomiasis, Poyang Lake region of Jiangxi Province from 1992 to 1996. METHODS: Annual mass chemotherapy and health education were implemented in all investigated individuals, in 1996, artesunate was used in high risk population in transmission season as a prophylactic measure. RESULTS: The prevalence of S. japonicum infection reduced from 26.0% in 1992 to 10.7% in 1994, the intensity of infection (geometric mean of EPG of feces) in residents decreased from 1.92 in 1992 to 0.55 in 1994, and the morbidity indicators such as hepatomegaly and splenomegaly in the cases also have been improved significantly after chemotherapy. In 1995, both the infection rate and intensity of infection of schistosomiasis were recurred from 10.7% and 0.55 in 1994 to 18.4% and 1.04 respectively due to the floods. In 1996, the infection rate reduced to 5.0% and the intensity of infection also decreased to 0.25 due to the additional measure. CONCLUSION: A mass chemotherapy in conjunction with health education and oral artesunate for preventing reinfection in transmission season is effective for the control of schistosomiasis in lake regions.

Adolescent↗
PubMed1999

[Relationship between HBV DNA serum level and acute exacerbation of the disease in chronic hepatitis B patients].

OBJECTIVE: In this study, we evaluated the relationship between HBV DNA serum level and acute hepatic exacerbation of the disease in chronic hepatitis B patients. METHODS: A series of serum samples from 14 patients of acute exacerbation of chronic hepatitis B were analyzed for alteratieus in serum HBV DNA and alanine transaminase (ALT) level before, during, and after episode of an acute exacerbation. The serum HBV DNA concentrations were tested by the quantitative polymerase chain reaction (PCR) using the AmpliSensor assay. RESULTS: 1. Serum HBV DNA average level in 11 patients significantly increased from 7.148 +/- 2.008(logarithm) at 2-8 weeks before maximum injury of liver to 8.416 +/- 2.160 (logarithm), the time that ALT reached its peak, and then, following the declining of ALT level, decreased to 6.093 +/- 1.428 (logarithm). In 9 of 11 cases, the HBV DNA peak value occurred before the ALT peak level or at the same time; 2. Two patients who experienced several episodes of acute exacerbation showed that the appearance of acute hepatic injury and the relatively normal liver function occurred alternatively. Whereas, one patient with liver cirrhosis showed persistence of high level viremia in three episodes of acute exacerbation in one year. CONCLUSION: 1. This investigation revealed a clear correlation between increasing level of serum HBV DNA and acute exacerbation of patients with chronic hepatitis B. The findings suggest that host's immune response which causes acute exacerbation of liver injury in patients with chronic hepatitis B is triggered by the change of viremia and HBV replication; 2. Patients with severe chronic active hepatitis and persistent hepatitis B virus replication are at very high risk of rapid progression to cirrhosis.

Adult↗