Biomedical subjects

X Gong

Publications and source records attributed to X Gong.

At least 55 records · Page 3Linked to original sources

PubMed1999

The effects of tetrandrine on the contractile function and microvascular permeability in the stunned myocardium of rats.

The effects of tetrandrine (Tet) on the contractile function and microvascular permeability in stunned rat myocardium in vivo were studied. Stunned myocardium was induced by 15 (MS(15) group) or 20 (MS(20) group) min of myocardial ischemia plus 60 min of reperfusion. The following was shown. (1) FITC-BSA concentration was 166.0 +/- 7. 9 microg/g myocardium in the control group. The concentrations in ischemic myocardium increased by 35.4 and 45.6% in MS(15) and MS(20) groups respectively (p<0.05). (2) Administration of Tet (64.2 and 96. 3 micromol/kg, I.P.) 20 min before ischemia not only ameliorated the contractile function, but also reduced the FITC-BSA concentrations in ischemic myocardium. At 60 min after reperfusion, the contractile function parameters in Tet-treated groups were significantly superior to those in corresponding stunning groups. FITC-BSA concentrations in Tet-treated groups were lower than those in stunning groups. Then, there was already no significant difference in FITC-BSA concentrations between Tet-treated groups and the control group. The FITC-BSA concentrations at the end of experiments were correlated negatively with dp/dt(max) (r = -0.83, p<0.01). (3) Tet inhibited KCl-induced calcium influx in isolated cardiomyocytes. The results suggest that Tet given before ischemia may be involved in the reduction of microvascular permeability in stunned myocardium, which might be associated with its calcium channel blocking effect.

Alkaloids↗

PubMed1999

A molecular perspective on the genera Paragonimus Braun, Euparagonimus Chen and Pagumogonimus Chen.

The status of the genera Euparagonimus Chen, 1963 and Pagumogonimus Chen, 1963 relative to Paragonimus Braun, 1899 was investigated using DNA sequences from the mitochondrial cytochrome c oxidase subunit I (CO1) gene (partial) and the nuclear ribosomal DNA second internal transcribed spacer (ITS2). In the phylogenetic trees constructed, the genus Pagumogonimus is clearly not monophyletic and therefore not a natural taxon. Indeed, the type species of Pagumogonimus, P. skrjabini from China, is very closely related to Paragonimus miyazakii from Japan. The status of Euparagonimus is less obvious. Euparagonimus cenocopiosus lies distant from other lungflukes included in the analysis. It can be placed as sister to Paragonimus in some analyses and falls within the genus in others. A recently published morphological study placed E. cenocopiosus within the genus Paragonimus and probably this is where it should remain.

Animals↗

PubMed1999

[Experimental study of ta chengchi tang decoction for relieving lung injury during acute necrotizing pancreatitis].

The objectives of the study were to investigate the changes of leukocyte adhesiveness and tumor necrosis factor (TNF) in the early stage of acute necrotizing pancreatitis (ANP), to go further into the relation of those changes to lung injury of ANP, and to evaluate the prohibitive effect of ta chengchi tang Decoction on leukocyte adhesion and TNF secretion. 14 canines were randomly divided into 3 groups. The treatment group (n = 5): experimental ANP model treated with ta chengchi tang Decoction; the saline control group (n = 5): experimental ANP model treated with normal saline; and the sham operative group (n = 4). The adhesion of leukocytes to vascular endothelial cells and TNF activities in serum and in bronchi-alveolar lavage fluid (BALF) were observed and measured, and the degrees of lung injury were assessed. The results showed that the adhesiveness of leukocytes was markedly increased and the activities of TNF were elevated in peripheral blood and BALF during ANP; that the leukocyte adhesiveness in the treatment group was weaker than that in the saline group (P < 0.05) and the serum and BALF TNF activities were also significantly lower than those in the saline group (P < 0.01); and that the degrees of lung injury in the treatment group were significantly milder than those in the saline group. These indicate that the increased leukocyte adhesiveness and hypersecretion of TNF take part in the pathogenesis of lung injury in ANP, and ta chengchi tang Decoction is demonstrated an efficacious medicine for alleviating the degree of lung injury mediated by both the leukocyte adhesion and TNF in ANP.

Animals↗

PubMed1999

Immunological studies on the cellular phenotype involved in corneal allograft rejection.

OBJECTIVE: To investigate the cellular phenotype involved in corneal allograft rejection using wholemounts analysis. METHODS: Corneal transplantation was performed between Sprague Dawley (SD) and Wistar rats. Corneal wholemounts were prepared from control rats and those after corneal transplantation on day 7 and 12. Immunohistochemical stain was performed on these wholemounts using monoclonal antibodies to transforming growth factor beta 1(TGF-beta 1), CD3, CD4, CD8, B lymphocytes, macrophages, dendritic cells and major histocompatibility complex (MHC) class II antigen. RESULTS: Corneal allograft rejection started on day 7 and reached its maximum from 10 to 14 days after corneal transplantation. Presence of TGF-beta 1-, CD3-, CD4-, CD8-, MHC class II-positive cells, macrophages and dendritic cells were noted at the limbus of both SD rats and Wistar rats. No positive cell was present in the central cornea of normal rats. All positive cells but B lymphocyte were noted in large numbers in the cornea after corneal allograft transplantation. Marked staining for TGF-beta 1 was noted during graft rejection. CONCLUSION: The corneal wholemounts technique provides a good visualization for the cellular phenotype involved in corneal allograft rejection. A variety of cells including TGF-beta 1, CD3, CD4, CD8, MHC class II antigen positive cells, macrophages and dendritic cells are involved in corneal allograft rejection. TGF-beta 1-positive cell might be an important immunosuppressive factor after corneal transplantation and also involved in the induction of fibrosis.

Animals↗

PubMed1999

[K-ras mutation in pancreatic juice from patients with pancreatic carcinoma].

OBJECTIVE: Pancreatic neoplasm, which is considered as one of the most malignant tumors in humans, is now increasing steadily in frequency. The 5-year-survival rate is less than 5%. In order to detect it in early stage, we tried to analyze K-ras mutation in pancreatic juice collected during ERCP after injection of secretin. Mutation of coden 12 in exon 1 of K-ras gene was reported as high as 90% in pancreatic cancer, but much less in benign pancreatic disease. METHODS: 47 patients at Peking Union Medical College Hospital between 1994 and 1998 were enrolled. Pancreatic juice collected during ERCP after injection of 100u secretin, was briefly centrifuged and the sediment was resuspended with PBS. Pancreatic juice supernatant and pancreatic cells were stored at -80 degrees C separately. DNA of the cells and supernatant of the juice were extracted. K-ras point mutation was investigated in the DNA of these supernatant and cells by means of two-stage polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). RESULTS: When the supernatant of the pancreatic juice was used, the PCR successful rate was 82%, K-ras mutation rate of the pancreatic carcinomas was 71% (15/21) compared with 0% (0/7) in benign pancreatic disease (3 chronic pancreatitis, 3 insulinoma and 1 pancreatic cyst). When the centrifuged pancreatic cells were used, the successful rate increased to 96%, sixty-five percent (11/17) of pancreatic carcinomas had K-ras mutation; mutation was also detected in 1/7 of the cases with benign pancreatic diseases (an insulinoma). In total, 78% (21/27) of the cases with pancreatic carcinomas has mutant alleles compared with 8% (1/13) of the benign pancreatic diseases (P < 0.001) when pancreatic juice was used to detect K-ras gene point mutation. In terms of the location of the pancreatic cancer, K-ras mutation rate was not statistically different between the head (80%) and the body + tail (75%). The mutation rate did not vary with the size of the tumor. CONCLUSION: Detection of coden 12 of K-ras mutation in pancreatic juice can be used in differentiating pancreatic carcinomas from benign pancreatic diseases. It has high sensitivity and specificity.

Genes, ras↗

PubMed1999

[A clinical analysis of Mooren's corneal ulcer].

OBJECTIVE: To investigate the clinical characteristics and to compare the effects of several therapies of Mooren's corneal ulcer. METHODS: 550 consecutive in-patients with Mooren's corneal ulcer were clinically analyzed, including the age, sex, laterality of the eye, ulcer location, rate of perforation, cure rate of surgeries, recurrent rate, and the effects of conjunctiva excision, lamellar keratoplasty (LKP), LKP plus cyclosporin A eye drops. RESULTS: The average age of onset of the ulcer was 48.4 years old, the ratio of male to female was 1:0.74, bilateral disease occurred in 165 cases (30.0%) of whom 52 cases (31.5%) were in the younger group and 113 (68.5%) in the older group. There were 501 eyes (70.1%) with the ulcer located at the limbus of palpebral fissure, and 95 out of 715 eyes with the disease had corneal perforation, the rate of perforation being 13.3%, 41 cases (43.2%) in the younger group and 54 cases (56.8%) in the older group. The postoperative recurrent rate was 25.6%. The cure rate of once LKP plus cyclosporin A eye drops was 73.7%, the final cure rate was 95.6%, and the preservative rate of the corneal anatomical structure of the surgeries was 99.7%. CONCLUSION: LKP plus cyclosporin A eye drops is an effective treatment of Mooren's corneal ulcer.

Adolescent↗

PubMed1999

[Glossus flap for hypopharyngeal reparation].

OBJECTIVE: To research the surgical type for hypopharyngeal reparation. METHOD: The glossus flap with glossus deep arterial was made to repairing hypopharyngeal breach after total laryngotomy and partial hypopharyngotomy in 12 cases of repeated laryngeal carcinoma and hypopharyngeal carcinoma. RESULT: 11 cases recovered in the swallowing function after 15 days and the pharyngeal fistula took place in one case, but healed in 35 days postoperatively. The survival rates in 1 year, 3 years and 5 years were 81.8%, 66.7% and 50% respectively. CONCLUSION: The glossus flap is good material for hypopharyngeal reparation with rich blood supply, few complication and high survival rates.

Adult↗

PubMed1999

[Sequencing of cytochrome C oxidase 1 gene of Ancylostoma duodenale and Necator americanus].

AIM: To identify the genetic diversity between Ancylostoma duodenale and Necator americanus. METHODS: Mitochondrial cytochrome C oxidase subunit 1 (CO1) gene was amplified from genomic DNA of human hookworms collected from infected patients in Hejiang County, Sichuan Province, and the purified PCR products were directly sequenced by using Licor auto-sequencer. RESULTS: The PCR products were about 700 bp. Alignment of CO1 gene fragment sequences showed 89.7% similarity between Ancylostoma duodenale and Necator americanus, but still certain nucleotide variations (10.3%) existed. CONCLUSION: CO1 gene sequence can be used as a marker to identify the two species of human hookworms.

Amino Acid Sequence↗

PubMed1999

[The influence of different treatment of the etched enamel on bracket bonding effect]

OBJECTIVE:To inquire into the influence of three different treatment of the etched enamel on bracket bonding effect. METHODS:Compared the bracket bonding failure rate and ARI counts of 30 cases which treat the etched enamel surface with 5s air-water gun rinsing, wet cotton ball wiping and alcohol cotton ball wiping respectively. RESULTS: The bracket bonding failure rate of the group which rinse the etched enamel 5s with air-water gun in the lowest one.There are statistically significant difference between this group and two others.The ARI count of this group is higher than that of others. CONCLUSION:The results suggest that rinse the etched enamel with the air-water gun is a very important step to prevent the bracket bonding failure.

Journal Article↗

PubMed1998

Gap junctional coupling in lenses lacking alpha3 connexin.

Fiber cells of the lens are interconnected by an extensive network of gap junctions containing alpha3 (Cx46) and alpha8 (Cx50) connexins. A specific role for these connexins in lens homeostasis is not known. To determine the contribution of these connexins to lens function, we used impedance techniques to study cell-to-cell coupling in lenses from homozygous alpha3 knockout (-/-), heterozygous (+/-), and wild-type (+/+) mice. Western blots and immunofluorescence data indicated that alpha8 remained at similar levels in the three classes of lenses, whereas alpha3 was approximately 50% of the normal level in the +/- lenses, and it was absent from the -/- lenses. Moreover, the data from +/+ lenses suggest that a cleavage of connexins occurs abruptly between the peripheral shell of differentiating fibers (DF) and the inner core of mature fibers (MF). The appearance of the cleaved connexins was correlated to a change in the coupling conductance. In -/- lenses the coupling conductance of MF was zero, and these fibers were depolarized by about 30 mV from normal (approximately -65 mV). The DF remained coupled, but the conductance was reduced to 30-35% of normal. However, the gap junctions in the DF of alpha3 -/- lenses remained sensitive to pH. We conclude that alpha3 connexin is necessary for the coupling of central fibers to peripheral cells, and that this coupling is essential for fiber cell homeostasis because uncoupled MF depolarize and subsequently become opaque.

Animals↗

PubMed1998

Calorie restriction, stress and the ubiquitin-dependent pathway in mouse livers.

Calorie restriction (R) is the only known method to delay the aging process and extend mean and maximal lifespan in rodents. R has been shown to delay the age-related accumulation of damaged proteins and to protect organisms from various stresses which can produce damaged proteins. Such stresses include irradiation, heat shock, and oxidative stress. The ubiquitin- and ATP-dependent proteolytic pathway (UPP) has been associated with the degradation of abnormal and/or damaged proteins. We examined the effect of diet and oxidative stress on activities of the UPP in supernatants from livers taken from 23-month-old Emory mice which had been exposed to an in-vivo injection of paraquat. Paraquat induces oxidative stress by generating superoxide radicals. In livers from non-stressed animals, steady-state levels of endogenous ubiquitin conjugates, de novo conjugate formation, and E1 and E2 activities were significantly lower in R animals than in control (C) animals. However, after exposure to paraquat, levels of endogenous ubiquitin conjugates were significantly higher in R versus C animals, and de novo conjugate formation and E1 and E2 activities in R animals rose to levels which were indistinguishable from levels of these activities noted in C animals. R was associated with an increased ability to degrade beta-lactoglobulin by the UPP after an oxidative stress was imposed. Ability to degrade beta-lactoglobulin by the C or R livers in non-stressed animals was not significantly different. Taken together, these data indicate that oxidative stress in R animals is associated with enhanced levels of ubiquitin conjugates and that this enhancement may be due to an increase in UPP activity. These data also indicate that the ability to form ubiquitin conjugates and the UPP system does not change with oxidative stress in C animals. The latter is consistent with prior reports that suggests that older C animals may already be in a state of enhanced oxidative stress and that activities of the UPP provide a sensitive indicator of levels of cellular redox status.

Adenosine Triphosphate↗

PubMed1998

HIV-1 envelope gp120 inhibits the monocyte response to chemokines through CD4 signal-dependent chemokine receptor down-regulation.

Since HIV-1 infection results in severe immunosuppression, and the envelope protein gp120 has been reported to interact with some of the chemokine receptors on human T lymphocytes, we postulated that gp120 may also affect monocyte activation by a variety of chemokines. This study shows that human peripheral blood monocytes when preincubated with gp120 either purified from laboratory-adapted strains or as recombinant proteins exhibited markedly reduced binding, calcium mobilization, and chemotactic response to chemokines. The gp-120-pretreated monocytes also showed a decreased response to FMLP. This broad inhibition of monocyte activation by chemoattractants required interaction of gp120 with CD4, since the effect of gp120 was only observed in CD4+ monocytes and in HEK 293 cells only if cotransfected with both chemokine receptors and an intact CD4, but not a CD4 lacking its cytoplasmic domain. Anti-CD4 mAbs mimicked the effect of gp120, and both anti-CD4 Ab and gp120 caused internalization of CXCR4 in HEK 293 cells provided they also expressed CD4. Staurosporine blocked the inhibitory effect of gp120 on monocytes, suggesting that cellular signaling was required for gp120 to inhibit the response of CD4+ cells to chemoattractants. Our study demonstrates a broad suppressive effect of gp120 on monocyte activation by chemoattractants through the down-regulation of cell surface receptors. Thus, gp120 may be used by HIV-1 to disarm the monocyte response to inflammatory stimulation.

CD4 Antigens↗

PubMed1998

The effects of aging and calorie restriction on plasma nutrient levels in male and female Emory mice.

We examined the effect of diet, age (4.5, 13 and 23 months), and sex on plasma levels of retinol, tocopherol, ascorbate, cholesterol, glucose and glycohemoglobin in male and female Emory mice which were fed control (C) and 50% calorie restricted (R) diets. Results showed that C fed animals tended to have higher levels of plasma ascorbate (50-71%), cholesterol (23-71%), glucose (38-81%) and glycohemoglobin (50%). However, these diet differences varied with the age and sex of the animals. Plasma retinol levels were lower only in R males vs. C males (50%). Novel sex-related differences in levels of plasma retinol (2-fold higher in C male mice than in C or R female mice) are described. Aging was associated with trends towards lower levels of plasma ascorbate (14-25%), glucose (34-36%) and glycohemoglobin (47-57%) from 4.5 to 23 months of age. However, these age differences depended upon the diet and sex of the animals. These data suggest that lower plasma levels of glucose, glycosylated hemoglobin and cholesterol may be causally related to the life extension noted in R animals since elevated levels of these moieties have been related to aging. Since oxidative stress is thought to be causally related to aging it appears unlikely that retinol, tocopherol and ascorbate are causally related to R-induced life-extension.

Aging↗

PubMed1998

Requirements for the adaptor protein role of dihydrolipoyl acetyltransferase in the up-regulated function of the pyruvate dehydrogenase kinase and pyruvate dehydrogenase phosphatase.

The dihydrolipoyl acetyltransferase (E2 component) is a 60-mer assembled via its COOH-terminal domain with exterior E1-binding domain and two lipoyl domains (L2 then L1) sequentially connected by mobile linker regions. E2 facilitates markedly enhanced function of the pyruvate dehydrogenase kinase (PDK) and pyruvate dehydrogenase phosphatase (PDP). Human E2 structures were prepared with only one lipoyl domain (L1 or L2) or with alanines substituted at the sites of lipoylation (Lys-46 in L1 or Lys-173 in L2). The L2 domain and its lipoyl group were shown to be essential for markedly enhanced PDP function and were required for greatly up-regulated PDK function. The complete absence of the L1 domain reduced the enhancements of both of these activities but not the maximal effector-stimulated PDK activity through acetylation of L2. With nonlipoylated L2 present, lipoylated L1 supported a lesser enhancement in PDK function with significant stimulation upon acetylation of L1. Prevention of L1 lipoylation in K46AE2 removed this competitive L1 role and enhanced L2-facilitated PDK activity beyond that of native E2 when PDK activity was measured in the absence or in the presence of stimulatory effectors. Thus, the E2-L2 domain has a paramount role in facilitating enhanced PDK and PDP function but inclusion of E2-L1 domain, even in a noninteracting (nonlipoylated) form, contributes to the marked elevation of these activities.

Acetyltransferases↗

PubMed1998

Aging, calorie restriction and ubiquitin-dependent proteolysis in the livers of Emory mice.

Calorie restriction (R), the only known method to delay the aging process and extend mean and maximal lifespan, has been shown to delay the age-related decline in protein degradation. There are several proteolytic pathways. The ubiquitin- and ATP-dependent proteolytic pathway (UPP) is frequently associated with degradation of damaged abnormal and/or regulatory proteins. We examined the effect of aging and R on supernatants of livers taken from young (4.5 months) and old (23 months) Emory mice. Aging was associated with increased levels of endogenous ubiquitin conjugates, enhanced ability to form high molecular weight conjugates and ubiquitin activating (E1) and ubiquitin conjugating (E2) activity in the control (C) liver supernatants. The age-related increase in levels of endogenous ubiquitin conjugates in liver appears to be primarily due to increased E1 and E2 activities. R prevented the age-related increase in E1 and E2 activity, and thus prevented the age-related increase in levels of ubiquitin conjugates. In spite of the age-related increase in ubiquitin conjugates, no age-related changes in ubiquitin-dependent proteolytic pathway were observed in the C animals. R was associated with an enhanced ability (130%) to degrade beta-lactoglobulin by the ubiquitin-dependent proteolytic pathway in livers from 4.5-month-old animals relative to age-matched C livers. However, rates of the ubiquitin-dependent degradation of beta-lactoglobulin in the 23-month-old C and R animals were indistinguishable. There were no age- or diet-related differences in the ability to degrade another substrate, oxidized ribonuclease (RNase).

Adenosine Triphosphate↗

PubMed1998

Redox regulation of ubiquitin-conjugating enzymes: mechanistic insights using the thiol-specific oxidant diamide.

The ubiquitin-proteasome pathway (UPP) regulates critical cell processes, including the cell cycle, cytokine-induced gene expression, differentiation, and cell death. Recently we demonstrated that this pathway responds to oxidative stress in mammalian cells and proposed that activities of ubiquitin-activating enzyme (E1) and ubiquitin-conjugating enzymes (E2s) are regulated by cellular redox status (i.e., GSSG:GSH ratio). To test this hypothesis, we altered the GSSG:GSH ratio in retinal pigment epithelial cells with the thiol-specific oxidant, diamide, and assessed activities of the UPP. Treatment of cells with diamide resulted in a dose-dependent increase in the GSSG:GSH ratio resulting from loss of GSH and a coincident increase in GSSG. Increases in the GSSG:GSH ratio from 0.02 in untreated cells to > or = 0.5 in diamide-treated cells were accompanied by dose-dependent reductions in the levels of endogenous Ub-protein conjugates, endogenous E1-ubiquitin thiol esters, and de novo ubiquitin-conjugating activity. As determined by the ability to form E1-ubiquitin and E2s-ubiquitin thiol esters, E1 and E2s were both inhibited by elevated GSSG:GSH ratios. Inhibition of E1 was associated with the formation of E1-protein mixed disulfides. Activities of E1 and E2s gradually recovered to preoxidation levels, coincident with gradual recovery of the GSSG:GSH ratio. These data support S-thiolation/dethiolation as a mechanism regulating E1 and E2 activities in response to oxidant insult. Ubiquitin-dependent proteolytic capacity was regulated by the GSSG:GSH ratio in a manner consistent with altered ubiquitin-conjugating activity. However, ubiquitin-independent proteolysis was unaffected by changes in the GSSG:GSH ratio. Potential adaptive and pathological consequences of redox regulation of UPP activities are discussed.

Cell Line, Transformed↗

PubMed1998

[Epidemiological features of sexually transmitted diseases among children below age 15 at the National STD Surveillance sites].

In order to understand the trends and epidemiological characteristics of sexually transmitted diseases among children below the age of 15 at national STD surveillance sites which will lead to the development of strategies on prevention and control, STD surveillance at selected national sites had been consecutively monitored during the period of 1987-1996 with data collected and analyzed. The epidemiological characteristics of STD among children below age 15 were found as follows: (1) Incidence rates of STD in children appeared to be ascending yearly, from 0.51/100,000 in 1987 to 8.62/100,000 in 1996. (2) Gonorrhea was the most frequently seen sexually transmitted disease among children, constituting 85.58% of the kinds of STDs on average. However, the proportion of gonorrhea cases in children is declining with the increase of NGU and syphilis. (3) Incidence rates among girls were consistently higher than the rates for boys, with a sex ratio of 2.35:1. (4) Incidence rate in group--0 was 44.68 per 100,000 population in 1996, much higher than the rates in other groups of children. (5) Incidence rates among children in both urban and minority areas were higher than the rates in rural area. The STD situation in children at the national STD surveillance sites has become crucial which calls for more attention.

Adolescent↗

PubMed1998

[An analysis of curative effect of activator in treating Class II division 1 malocclusion].

OBJECTIVE: To analyze the results of class II division 1 malocclusion treated by activator. METHODS: Sixteen growing patients, who were diagnosed as class II division 1 malocclusion, were evaluated by McNamara analysis. RESULTS: The activator affects the growth of mandible positively and inhibits the growth of the maxilla. CONCLUSION: The activator can treat class II division 1 malocclusion effectively, which can be perceived by McNamara analysis directly.

Adolescent↗