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Biomedical subjects

G Sun

Publications and source records attributed to G Sun.

At least 73 records · Page 4Linked to original sources
PubMed2001

[A study on the use of traditional Chinese medicine agent in ultrasonic instrumentation of root canals].

OBJECTIVE: To evaluate the bactericidal effect for anaerobes of infected root canals using Chinese medicine agent Jieeryin combing with ultrasonic technique. METHODS: 60 single-rooted teeth in patients with chronic periapical periodotitis were divided into 3 groups randomly, 20 in each. Hand instruments were used for group 1 as control group of traditional treatment. Ultrasound with saline as irrigant were used for group 2 as control group. Ultrasound with Jieeryin as irrigant were used for group 3 as experimental group. The pre-instrumentation and post-instrumentation specimens of each root canal were placed into the anaerobic chambers and incubated. RESULTS: Significant difference was found between hand instruments group and control group of ultrasound (P < 0.05) and even more significant difference was found between control group of ultrasound and experimental group of ultrasound (P < 0.01). CONCLUSIONS: Ultrasound has special superiority on instrumentation and bactericide of root canals. Chinese medicine agent Jieeryin can kill anaerobes in infected root canals effectively. It is an ideal irrigant for ultrasound which conforms to principles of biology.

Adolescent↗
PubMed2001

[Primary cutaneous CD30-positive anaplastic large cell lymphoma].

OBJECTIVE: To analyse the clinical manifestations, pathological and immunohistochemical features of 9 cases of primary cutaneous CD30-positive anaplastic large cell lymphoma (ALCL) in order to improve the criteria for its early and differential diagnosis. METHODS: Histopathological method was used to study the morphological characteristics. Immunohistochemical stainings (SP or ABC method) for leukocyte common antigen (LCA), CD20, CD30, CD45RO, CD68, epithelium membrane antigen (EMA), cytokeratin (CK) and HMB45 were applied to the routine paraffin sections of all the 9 cases. RESULTS: The 9 cases of primary cutaneous CD30-positive ALCL consisting of 6 males and 3 females, aged 31 to 84 years (mean 58.2 years). All patients presented with subcutaneous masses or papular eruptions on lower trunk and extremities. Histopathologically, the lesions were composed of numerous large round, oval or pleomorphic cells with abundant cytoplasm, amphophilic or basophilic, and large nucleus with distinct nucleolus. Mitosis was often observed. Multinucleated giant cells and Reed-Sternberg cells may be seen. The neoplastic cells displayed positive antigen markers for CD30 in 9 cases, 6 positive for CD45RO and 3 cases negative for both CD45RO and CD20. Two patients died of metastasis, 2 patients experienced recurrence and 5 patients still well during follow-up. CONCLUSIONS: Primary cutaneous CD30-positive ALCL is a morphologically distinctive neoplasm with a comparatively favorable prognosis. This tumor can be differentiated from other malignant tumors on the basis of histopathologic features and positive CD30 which is of significance.

Adult↗
PubMed2001

[Clinical characteristics of primary biliary cirrhosis with Sjögren's syndrome of 20 cases].

OBJECTIVE: Primary biliary cirrhosis (PBC) is a chronic non-suppurative destructive cholangitis of unknown etiology. It has been reported that patients with PBC suffer from xerostomia and keratoconjunctivitis at high prevalence and PBC has been shown to be associated with Sjögren's syndrome. This study investigated the relationship between PBC and Sjögren's syndrome. METHOD: 20 cases diagnosed as PBC consented to the evaluation for Sjögren's syndrome which included clinical and serological features, Schirmer's test, measurement of parotid flow rate and labial minor salivary gland biopsy. RESULTS: The main manifestations of PBC are jaundice, pruritus, hepatosplenomegaly. M2 subtype of antimitochondrial antibody is of great specificity for PBC. Many PBC patients are suffering from xerostomia and keratoconjunctivitis sicca but do not have typical serological and pathological presentations of primary Sjögren's syndrome. Corticosteroids and immunosuppressive agents have disappointing effects in the treatment. Ursodeoxycholic acid is effective to certain extent. CONCLUSION: It was indicated that Sjögren's syndrome associated with PBC appears to be a secondary form differing from primary Sjögren's syndrome.

Adult↗
PubMed2001

[A preliminary study on infection of rabbits by human cytomegalovirus AD169 strain].

BACKGROUND: To study the susceptibility of rabbit to human cytomeglavirus (HCMV) in vivo and in vitro. METHODS: Rabbit embryo lung (REL) cell monolayer were inoculated with HCMV AD169 strain. The cytopathic effect (CPE) was observed by microscope. HCMV antigen was detected by immunohistochemical method and viral particles were shown by electron microscopy. Human embryo lung (HEL) was taken control. Thirty New Zealand rabbits were divided into three groups randomly, two were virus groups (group1, group2) and one was inactivated virus group (group3). 50 days later, the rabbits tissue lesions were observed by pathological techniques, HCMV DNA was analyzed by in situ hybridization. RESULTS: The CPE appeared 16 h post inoculation in REL cells as well as in HEL cells, at the same time, the HCMV antigen also was detected by immunhistochemistry and a large number of viral particles were manifested in the nucleus and cytoplasm of REL cells by electron microscope 36 h after virus inoculation. The extensive pathological damages in tissues of HCMV infected rabbits were observed and the viral DNA was also demonstrated in many tissues of HCMV infected rabbits. CONCLUSIONS: HCMV can infect REL cells and fulfil its replication cycle in vitro. HCMV AD169 strain can infect rabbits through intravenous injection and different infection models can be established by controlling the dosage of inoculated virus.

Animals↗
PubMed2001

Biorheological characteristics of skin after expansion.

This study investigated the changes in biorheological characteristics of skin after expansion. Expanders were implanted into the back of eight adult dogs, and after an eight-week expansion the expanded and the non-expanded control skins were transferred to an adjacent site. The expanded specimens and their controls were obtained at 3, 6, 12 and 24 weeks after transfer, and their biorheological characteristics and histological changes were studied. The characteristics of the stress-relaxation, the stress-strain relationship and tensile strength of the expanded and control specimens were measured. The tests demonstrated that during the initial stage after transfer, the biorheological properties of experimental specimens differed significantly from those of their controls. However, the differences between expanded and control specimens began to lessen gradually with increasing recovery time. When the recovery time reached 24 weeks or longer, the experimental skin exhibited the same mechanical properties as the control skin. Histological examination of expanded specimens showed thickened epidermis and thinned dermis. But there were no significant histological differences between expanded skins and their controls after 24 weeks.

Animals↗
PubMed2001

[Detection of aflatoxin-albumin adducts in human serum and its application].

Exposure to aflatoxin B1 (AFB1) is one of the major risk factors in the etiology of human hepatocellular carcinoma (HCC). The development of highly sensitive and specific methods for detecting AFB1 and its macromolecular biomarkers are critical for identifying individuals at risk for hepatocellular carcinoma. The detection of aflatoxin-albumin adducts (AFB-ALB) in serum has been used to investigate the relationship between aflatoxin exposure and HCC. A more sensitive and reliable method to detect AFB-ALB in serum was modified by separating serum albumin with Microcon-50 microconcentrators in stead of using precipitation. The method could separate serum albumin quickly and make protein digested in the same container. Thus, the step for transferring samples was reduced and recovery rate was improved. The AFB-ALB adducts were then determined by radioimmunoassay. The AFB-ALB adducts of human serum samples from Qidong, Jiangsu Province, and Fusui, Guangxi Zhuang Autonomous Region of the People's Republic of China were detected. The results indicated that the exposure of AFB1 is common and the positive rate for AFB-ALB adducts in serum of these populations is high.

Aflatoxin B1↗
PubMed2001

[Effects of estrogen in the central nervous system].

Estrogen exerts a variety of effects (including electrophysiological, neutrophic and metabolic effects) on neurons in the adult central nervous system. With the many progresses made in the study of estrogen signaling through both genomic and nongenomic pathways, awareness of estrogen's effects on neural function is broadening rapidly. And it also helped people to understand more about the mechanisms by which estrogen regulating GnRH neurons, inducing or maintaining dendritic spine in hippocampus and protecting neurons from a variety of insults. Recently, epidemiological studies have suggested that estrogen, as a hormone replacement therapy in postmenopausal women, may protect against Alzheimer's disease (AD). Findings in these areas demonstrate a role for estrogen that is beyond direct control of reproductive function.

Alzheimer Disease↗
PubMed2001

[Effect of "yang wei kang liu" granula on expression of P53 and PCNA in mice bearing sarcoma 180].

OBJECTIVE: To study possible mechanism of "Yang Wei Kang Liu" (YWKL) granula in treating tumor. METHODS: Mice bearing sarcoma180 and immunohisto-chemical method were adopted. RESULTS: Both YWKL granula and its cooperated chemothrapy could restrain the expression of P53 and PCNA. Compared with the chemotherapy group and the cooperated chemotherapy, YWKL granula group was significantly different. CONCLUSION: YWKL granula could restrain the expression of P53 and PCNA, and increase the effect together with chemotherapy.

Animals↗
PubMed2001

[Relationship between TT virus infection and hepatocellular carcinoma].

OBJECTIVE: To clarify the relationship between TT virus (TTV) infection and the development of hepatocellular carcinoma (HCC). METHODS: TTV was examined in sera of 112 patients with HCC and 95 patients with chronic liver disease (CLD) without HCC. 30 patients without liver disease were examined as control. TTV DNA was detected by the second generation of TTV PCR primers (NG059, NG061 and NG063) after extraction of DNA from 50 microliters serum. The relationship between TTV infection and clinical features of each group patients was analyzed. RESULTS: TTV DNA was detected in 17.86% (20/112) of HCC patients, and this prevalence in HCC patients was not significantly higher than that of TTV DNA in CLD patients (15.78%, 15/95). There were no significant differences in age, gender, tumor factors (size, TNM classification and markers) and other hepatitis virus markers between TTV-positive and TTV-negative in HCC and CLD patients, except history of blood transfusion [(80.00% vs 35.87% (P < 0.05) in HCC patients and 73.33% vs 27.50% (P < 0.05) in CLD patients)] and ALT [(93 +/- 27) IU/L vs (68 +/- 31) IU/L (P < 0.05) in HCC patients]. It seemed that TTV did not do any harm to the liver function of patients who infected with HBV or HCV, except for elevating ALT level in such a kind of HCC patients. CONCLUSION: Although TTV could do harm to the liver function of HCC patients, it does not contribute to the development of HCC from CLD.

Carcinoma, Hepatocellular↗
PubMed2000

Nitric oxide is neither necessary nor sufficient for resolution of Plasmodium chabaudi malaria in mice.

Malaria is a life-threatening re-emerging disease, yet it is still not clear how bloodstage malarial parasites are killed. Nitric oxide (NO), which has potent anti-microbial activity, may represent an important killing mechanism. The production of NO during descending Plasmodium chabaudi parasitemia, a period when parasites are killed by the immune response, supports this concept. However, NOS20/0 and NOS30/0 mice as well as mice treated with NO synthase 2 (NOS2) inhibitors do not develop exacerbated malaria, indicating that NO production is not necessary for the suppression of P. chabaudi parasitemia. It is possible due to the plasticity in the immune response during malaria that Ab-mediated immunity is enhanced in the absence of NO, thereby explaining the lack of exacerbated malaria in NOS-deficient mice even though NO may function in protection. However, NOS2- and B cell-deficient mice, which cannot use Ab-mediated immunity, suppress their parasitemia with a similar time course as B cell-deficient controls. C57BL/6 mice treated with Propionibacterium acnes to elicit high levels of macrophage-derived NO have a similar time course of P. chabaudi parasitemia as P. acnes-treated NOS20/0 mice, which do not produce NO; this indicates that NO is not sufficient for parasite killing. Collectively, these results indicate that NO is not necessary or sufficient to resolve P. chabaudi malaria.

Animals↗
PubMed2000

Zeta-crystallin catalyzes the reductive activation of 2,4,6-trinitrotoluene to generate reactive oxygen species: a proposed mechanism for the induction of cataracts.

Exposure to 2,4,6-trinitrotoluene (TNT) has been shown to cause induction of cataract in which oxidative stress plays a critical role. From bovine lens we purified to homogeneity and identified an enzyme that catalyzes the reduction of TNT, resulting in the production of reactive oxygen species. The final preparation of TNT reductase showed a single band with a subunit molecular weight of 38 kDa on SDS-PAGE. Sequence data from peptides obtained by digestion with lysylendopeptidase Achromobacter protease I (API) revealed that TNT reductase is identical to zeta-crystallin. Superoxide anions were formed during reduction of TNT by zeta-crystallin, though negligible enzyme activity or protein content for superoxide dismutase, a superoxide scavenging enzyme, was found in the lens. Thus, the present results suggest that the induction of cataracts by TNT may be associated with increased oxidative stress, as a result of reductive activation of TNT generating superoxide anions, there being minimal antioxidant enzyme activity for defense against reactive oxygen species exogenously produced in the lens.

Amino Acid Sequence↗
PubMed2000

Improved method for simultaneous determination of L-arginine and its mono- and dimethylated metabolites in biological samples by high-performance liquid chromatography.

An improved method has been developed for the determination of L-arginine and its methylated metabolites, N(G)-monomethyl-L-arginine (L-NMMA), N(G),N(G)-dimethyl-L-arginine (asymmetric DMA, ADMA) and N(G),N(G)'-dimethyl-L-arginine (symmetric DMA, SDMA) in biological samples. Extraction of these compounds with a strong cation-exchange resin AG50W-X8 with L-homoarginine (2-amino-6-guanidinohexanoic acid) as an internal standard gave a recovery of more than 70% except for SDMA from plasma samples. After extracted samples were converted to fluorescent derivatives with o-phthalaldehyde (OPA) in an alkaline medium, the following high-performance liquid chromatographic separation with a ODS column (wide-pore size, 300 A) was successfully performed with an isocratic mobile phase system. The method permits quantitative determination of L-arginine and its methylated metabolites at concentrations as low as 4 microM and 0.18 microM, respectively. Using this method, the levels of L-arginine, L-NMMA, ADMA and SDMA in human plasma, urine and rat tissue were determined.

Adult↗
PubMed2000

Cyclic peptides incorporating 4-carboxyphenylalanine and phosphotyrosine are potent inhibitors of pp60(c-)(src).

The protein tyrosine kinase, pp60(c-)(src), is involved in cellular signaling and is activated during mitosis and in various tumors. We have been employing cyclic decapeptides to identify the determinants for substrate binding and phosphorylation to develop inhibitors competitive with protein substrates of Src. A structure-activity study [McMurray, J. S., Budde, R. J. A., Ke, S., Obeyesekere, O. U., Wang, W., Ramdas, L., and Lewis, C. A. (1998) Arch. Biochem. Biophys. 355, 124] revealed that, at the position 3 residues C-terminal to the phosphorylated tyrosine (Y + 3), both glutamic acid and phenylalanine gave identical K(i), K(m), and V(max) values. We hypothesized that the area of Src that binds the Y + 3 residue contains either a positively charged lysine or an arginine, capable of ionic interactions with glutamic acid or cation-pi interactions with phenylalanine. To test this hypothesis, a series of phenylalanine analogues were substituted at position 7 (the Y + 3 residue) in cyclo(Asp(1)-Asn(2)-Glu(3)-Tyr(4)-Ala(5)-Phe(6)-Phe(7)-Gln(8)-D-Phe(9 )-Pro(10)). Of these, 4-carboxyphenylalanine (4-Cpa) and phosphotyrosine resulted in high affinity peptides exhibiting K(i) values of 0.85 and 1.1 microM, respectively, 180- and 130-fold increases in potency over the parent cyclic peptide (K(i) = 150 microM). These peptides were noncompetitive with respect to ATP and competitive against the phosphate-accepting substrate, polyGlu(4)Tyr. The truncated cyclic peptide, cyclo(Phe-4-Cpa-Gln-D-Phe-Pro-Asp-Aca) (Aca = epsilon-aminocaproic acid), which did not contain tyrosine, was also a competitive inhibitor with a K(i) value of 24 microM. We conclude that these cyclic peptides bind to a positively charged area that is near the phosphate transfer region of the active site of Src but does not necessarily include the tyrosine-binding pocket. Furthermore, the 4-Cpa-containing cyclic decapeptide shows remarkable selectivity in the inhibition of Src versus the src family members Yes and Lck, as well as other protein tyrosine kinases, Ser/Thr kinases, and other ATP-utilizing enzymes.

Animals↗
PubMed2000

Inhibition of carcinogen-induced rat mammary tumor growth and other estrogen-dependent responses by symmetrical dihalo-substituted analogs of diindolylmethane.

90%) by the haloDIMs at concentrations of 5 or 10 microM, and only 4, 4'-dichloroDIM alone increased cell proliferation. With the exception of 5,5'-difluoroDIM, the remaining compounds also inhibited E2-induced growth of MCF-7 human breast cancer cells. DihaloDIMs (100 mg/kg/dayx3) were not estrogenic in the immature female B6C3F1 mouse uterus; however, in animals co-treated with E2 (0.02 microg/mouse), 5,5'-dichloro- and 6,6'-dichloroDIM inhibited uterine progesterone receptor (PR) binding and uterine peroxidase activity, whereas 5,5'-dichloro- and 5,5'-dichloro-2,2'-dimethylDIM inhibited only the latter response. The antitumorigenic activities of the dihaloDIMs were determined by their inhibition of carcinogen-induced mammary tumor growth in female Sprague-Dawley rats. 4,4'-Dichloro-, 5,5'-dibromo- and 6,6'-dichloroDIM, significantly inhibited mammary tumor growth at doses of 1 mg/kg every second day, and no significant changes in organ weights or liver and kidney histopathology were observed. These three compounds were more active than DIM in the same in vivo assay.

Animals↗
PubMed2000

Yohimbine dimers exhibiting binding selectivities for human alpha2a- versus alpha2b-adrenergic receptors.

A series of yohimbine dimers was prepared and evaluated at the human alpha2a- and alpha2b-adrenergic receptors (ARs) expressed in Chinese hamster ovary (CHO) cells. All dimers display higher binding selectivities for alpha2a versus alpha2b subtype than yohimbine, and four compounds (3d, 3e, 3g and 3i) represent the most potent and alpha2a versus alpha2b-AR selective ligands identified so far.

Adrenergic alpha-2 Receptor Antagonists↗
PubMed2000

Decreased serum concentrations of nitric oxide metabolites among Chinese in an endemic area of chronic arsenic poisoning in inner Mongolia.

Prolonged exposure to arsenic results in peripheral and cardiovascular manifestations, as does impaired production of endothelial nitric oxide (NO). In vitro studies have indicated that endothelial cells undergo damage by arsenic. However, no information has been available on the relationship between NO synthesis and chronic arsenic poisoning in humans. The present study was designed to reveal this question. The subjects were 33 habitants who continued to drink well water containing high concentrations of inorganic arsenic (mean value = 0.41 microg/ml) for about 18 years in Inner Mongolia, China, and 10 other people who lived in this area but exposed to minimal concentrations of arsenic (mean value = 0.02 microg/ml) were employed as controls. Mean blood concentration of total arsenic was six times higher in exposed subjects than controls; 42.1 vs. 7.3 ng/ml, p <.001. Mean serum concentration of nitrite/nitrate, stable metabolites of endogenous NO, was lower in arsenic-exposed subjects than in controls: 24.7 vs. 51.6 microM, p<.001. In total samples, an inverse correlation with serum nitrite/nitrate levels was strong for blood inorganic arsenic (r = -0.52, p <.001) and less strong for its metabolites, monomethyl arsenic (r = -0.45, p<.005) and dimethyl arsenic (r = -0.37, p<.05). Furthermore, serum nitrite/nitrate concentration was significantly correlated with nonprotein sulfhydryl level in whole blood (r = 0.58, p<.001). In an in vitro study, we demonstrated that inorganic arsenite or arsenate suppresses the activity of endothelial NO synthase in human umbilical vein endothelial cells. These results suggest that long-term exposure to arsenic by drinking well water possibly reduces NO production in endothelial cells, resulting in a decrease in reduced nitrite/nitrate concentrations. Peripheral vascular disorders caused by arsenic may be attributable in part to impairment of NO production in vivo.

Adolescent↗
PubMed2000

In-Line Proximity Effects in Extended 7-Azanorbornanes. 1. A New Concept for Modifying Effector Group Separation Based on the Control of N-Invertomer Geometry.

Control of N-substituent geometry in fused 7-azanorbornane systems is based on the dominance of one proximate bridge (sentinel X) over the other (sentinel Y) relative to the N-bridge; the N-inversion equilibrium can effectively be displaced in favor of a single invertomer. This study has used a combination of synthesis, crystallography, and molecular modeling to establish stereostructures.

Journal Article↗