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Biomedical subjects

H Zheng

Publications and source records attributed to H Zheng.

At least 307 records · Page 17Linked to original sources
PubMed1996

Hepatocytes from metallothionein-I and II knock-out mice are sensitive to cadmium- and tert-butylhydroperoxide-induced cytotoxicity.

Metallothionein (MT) has been proposed to play an important role in heavy metal detoxication and in the scavenging of free radicals. Effects of MT on the cytotoxicity of cadmium (Cd), tert-butylhydroperoxide (t-BHP) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were examined using primary hepatocyte cultures from control (C57BL/6J) and MT-I and II knock-out (MT-null) mice. Compared to control hepatocytes, MT-null hepatocytes had minimal Cd-binding proteins (MT equivalents), but cellular glutathione concentration was similar to the control hepatocytes. MT-null hepatocytes were more sensitive than controls to the cytotoxic effects of Cd (50-300 microM) and t-BHP (125-500 microM), as indicated by the levels of lactate dehydrogenase released into the medium. Cd and t-BHP also produced more lipid peroxidation in MT-null hepatocytes than in control cells, as demonstrated by the abundance of thiobarbituric acid-reactive substances. However, MT-null hepatocytes were equally sensitive as controls to the cytotoxicity of MNNG (0.5-2.0 mM), suggesting that MT does not protect against MNNG-induced cytotoxicity. These results support the hypothesis that constitutive MT levels affect the sensitivity of mammalian cells to Cd and oxidative stress.

Animals↗
PubMed1996

Changes in methyl-sensitive restriction sites of liver DNA from hamsters chronically exposed to hydrazine sulfate.

Hydrazine sulfate is a genotoxic hepatocarcinogen for the hamster. A study was conducted to follow changes in DNA maintenance methylation in selected genes in liver DNA during the 21-month induction of liver adenomas and hepatocellular carcinomas by demonstrating changes in restriction fragment length polymorphism. Male Syrian golden hamsters were exposed to hydrazine sulfate in the drinking water at three concentrations (170, 340 and 510 mg/l) shown previously to result in a dose-dependent induction of liver tumors. Liver DNA from animals exposed to the high concentration for 6, 12, 16, 20 and 21 months and animals exposed to the low or mid concentration for 21 months was digested with EcoRI, MspI, HindIII or BamHI, or a combination of one of these endonucleases and a methyl-sensitive restriction enzyme, HpaII or HhaI. The DNA digests were subjected to Southern analysis using a c-DNA probe for one of the following genes: DNA methyltransferase (DMT), c-Ha-ras, c-jun, c-fos, and c-myc proto-oncogenes, p53 tumor suppressor gene or gamma-glutamyltranspeptidase. Alteration in DNA restriction by methyl-sensitive endonucleases was detected in four (DMT, c-Ha-ras, p53 and c-jun) of the seven genes examined and as early as 6 months in animals exposed to the highest concentration of hydrazine sulfate; alteration of recognition sites in c-Ha-ras was also detected in DNA from animals exposed for 21 months to the intermediate concentration of hydrazine sulfate. Early changes in recognition sites, presumed to indicate altered methylation status of DNA cytosine and/or guanine mutations, were seen using c-DNA probes for DMT, c-Ha-ras and c-jun; in the p53 tumor suppressor gene alteration of such sites was a late event relevant to appearance of liver adenomas and hepatocellular carcinomas. Evidence for hypomethylation in the p53 and c-jun genes and hypermethylation of the c-Ha-ras and DMT genes is provided. This study supports the induction of site-specific hypomethylation and hypermethylation during the course of hydrazine carcinogenesis.

Animals↗
PubMed1996

Successful eradication of sexually transmitted diseases in the People's Republic of China: implications for the 21st century.

The global control of sexually transmitted diseases (STDs) represents a daunting task, and there have been very few examples of success. The scope of the STD problem in China before the formation of the People's Republic and the effects of a governmental STD control program were reviewed. In major cities, 10% of the population had syphilis, reaching 50% prevalence in some rural minorities. By 1964, STDs in China were virtually eliminated through a program that destigmatized STDs, provided an infrastructure for case finding and therapy, and eliminated prostitution. The People's Republic of China demonstrated the possibility of eliminating STDs, at least for some period of time. Although the Chinese approach may not be ideal for Western democracies, understanding some features of the Chinese program may help in designing a strategy for the eradication of human immunodeficiency virus when or if treatment becomes available.

China↗
PubMed1996

Tumor cell resistance to apoptosis due to a defect in the activation of sphingomyelinase and the 24 kDa apoptotic protease (AP24).

Signal transduction pathways involved in apoptotic cell death are poorly understood, although recent studies have implicated sphingomyelin hydrolysis and generation of the second messenger, ceramide. Previous work in this laboratory demonstrated that a serine protease termed AP24 was activated by TNF or UV light and induced DNA fragmentation in isolated nuclei. This study extended these findings to examine the role of these enzymes in apoptosis of the U937 cell line and the mechanism of resistance of its variant, U9-TR. Although this subclone was selected by growth in TNF, it was unexpectedly found to resist apoptosis induced by UV light, but was still sensitive to anti-Fas-induced DNA fragmentation. Here we show that in contrast to normal U937 cells, UV light and TNF both failed to activate neutral or acidic sphingomyelinase or AP24 in the U9-TR variant. However, anti-Fas activated both neutral and acidic sphingomyelinase in the variant comparable to that seen in parental U937. The U9-TR variant could be sensitized to TNF or UV light activation of both sphingomyelinase and DNA fragmentation by the protein phosphatase inhibitors okadaic acid and calyculin A. Furthermore, exogenous bacterial-derived sphingomyelinase caused U9-TR activation of AP24 and DNA fragmentation comparable to that in the parental U937. Exposure of permeabilized U937 cells to ceramide caused internucleosomal DNA cleavage that was blocked by an inhibitor of AP24. Taken altogether, these findings demonstrate that TNF or UV light activate sphingomyelinase that leads to the generation of ceramide resulting in activation of AP24 and DNA fragmentation in sensitive cells. A selective defect in signals leading to sphingomyelinase activation can confer resistance to apoptosis even though the variant is still sensitive to downstream apoptotic signals such as nuclear DNA fragmentation by activated exogenous AP24.

Apoptosis↗
PubMed1996

Experimental study on reinnervation of vocal cord adductors with the ansa cervicalis.

The purpose of this study was to reestablish the adduction of the paralyzed vocal cord through reinnervation of the adductor muscles for unilateral vocal cord paralysis. In nine dogs, the adductor branch of the recurrent laryngeal nerve was anastomosed to the main branch of the ansa cervicalis. Six months later, various techniques of observation showed that seven of nine cases had excellent to good adduction during whining. Adduction was caused by reinnervation of the adductor muscles from the ansa cervicalis as demonstrated by laryngeal spontaneous and evoked electromyography, contraction tension, and various histologic findings. Therefore, the new technique could be a good treatment of unilateral vocal cord paralysis.

Animals↗
PubMed1996

Update: laryngeal reinnervation for unilateral vocal cord paralysis with the ansa cervicalis.

Eight patients underwent ansa cervicalis anastomosis to the adductor branch of the recurrent laryngeal nerve for unilateral vocal cord paralysis. They were followed long enough (at least 1 year) to determine if the procedure was successful. All cases have been subjected to preoperative and postoperative voice recording, acoustic analysis, and videolaryngoscopy. Some of them have been subjected to stroboscopy and electromyography (EMG). Data from these cases indicate that satisfactory phonatory quality may be achieved after the procedure. The reinnervated vocal cord neither abducted nor adducted, but it presented itself in midline for precise apposition with the normal cord. Synchronous mucosal waves in both vocal cords could be observed. EMG showed that the procedure produced satisfactory reinnervation of the adductory muscles. Therefore, the authors believe that the procedure could be proposed as an alternative to Teflon injection or thyroplasty in selected cases.

Adult↗
PubMed1996

Strain-specific reverse transcriptase PCR assay: means to distinguish candidate vaccine from wild-type strains of respiratory syncytial virus.

Candidate live-virus vaccines for respiratory syncytial virus are being developed and are beginning to be evaluated in clinical trials. To distinguish candidate vaccine strains from wild-type strains isolated during these trials, we developed PCR assays specific to two sets of candidate vaccine strains. The two sets were a group A strain (3A), its three attenuated, temperature-sensitive variant strains, a group B strain (2B), and its four attenuated, temperature-sensitive variant strains. The PCR assays were evaluated by testing 18 group A wild-type strains, the 3A strains, 9 group B wild-type strains, and the 2B strains. PCR specific to group A wild-type strains amplified only group A wild-type strains, and 3A-specific PCR amplified only 3A strains. PCR specific to group B wild-type strains amplified all group A and group B strains but gave a 688-bp product for group B wild-type strains, a 279-bp product for 2B strains, a 547-bp product for all group A strains, and an additional 688-bp product for some group A strains, including 3A strains. These types of PCR assays can, in conjunction with other methods, be used to efficiently distinguish candidate vaccine strains from other respiratory syncytial virus strains.

Base Sequence↗
PubMed1996

[Clinical summary of relatively large dose of sodium morrhuate injection for the treatment of maxillofacial cavernous hemangionma:A report of 764 cases]

The result of relatively large dose of 5% sodium morrhuate injection(SIM) for the treatment of 764 cases in the cavernous hemangioma in orofacial region is presented.The curative rate was improved,Its cure and elementary cure rate were 89.27%.The dosage,course and practical approach were discussed,The relationship of factors listed above with the curative effect were mentioned.The reaction and complications might be influencing the recurrence rate.Hemangioma after SMI should be observed in order to consolidate its curative effect.

Journal Article↗
PubMed1996

[Studies on the immunopathogenesis of experimental tubulointerstitial nephritis in Wistar rats].

Tubulointerstitial nephritis (TIN) model was successfully induced in female Wistar rats by immunization with rabbit tubular basement membrane (TBM) etc. By using immunohistochemistry and computer assisted image processing, characterization of mononuclear cells in the TIN models were determined, and the relationship between Ia antigen expression of renal tissue and TIN studied. The results showed: TIN was characterized by deposition of IgG in a linear pattern along TBM and mononuclear cells infiltrates, which suggests the production of anti-TBM antibodies. Among the mononuclear cells, most are T cells. Granuloma formation was observed in parts of TIN. B cells gradually decreased while monocytes gradually increased. The renal tissue lesions show tubular atrophy and peritubular fibrosis. This model strongly suggests that cellular immune responses play an important role in the development of TIN. Ia antigen expression is higher in cells of the tubular epithelium and Bowman's capsule of lesion site than in control group (P < 0.01). This is strong evidence that the abnormal expression of Ia antigen may be affected by the production and development of TIN.

Animals↗
PubMed1996

[Dynamic assay of oleanolic acid in Aralia taibaiensis Z. Z. Wang et H. C. Zheng].

The dynamic assay on oleanolic acid (OA) in Aralia taibaiensis shows that the plant has a higher OA level. The level in root cortex is 4.74%-10.81% and peak stages are mid-May to late June and late August to mid-September the level in stem barks is 3.59%-12.06% and peak period is between mid-May and late July, the level in leaves increases throughout the life time ranging from 2.41% to 6.66% and peak level is 6.66% around mid-September.

Drugs, Chinese Herbal↗
PubMed1996

[Laryngeal reinnervation by nerve-muscle multipedicle transfer].

Abductive ability was restored by means of a modified nerve-muscle pedicle technique, utilizing nerve-muscle multipedicle and multipoint implantation in seventeen dogs. The results showed that the procedure was superior to traditional Tucker's technique in functional recovery, electrophysiological activity and muscle strength which was also demonstrated by histochemical studies. There was little difference between double and three nerve-muscle pedicle transfer. The procedure has been used in three patients with bilateral vocal cord paralysis. Return of spontaneous abduction in the operated side in two patients was noted after eight and twelve weeks after surgery. All patients have achieved sufficient airway without the need of tracheotomy. Electromyography confirmed the reinnervation of posterior cricoarytenoid muscle.

Animals↗
PubMed1996

Changes in local immune functions in Mooren's ulcer.

PURPOSE: To the investigate changes in local immune functions of the cornea and the adjacent conjunctiva, and their roles in the mechanism of the disease. METHOD: The cornea and adjacent bulbar conjunctiva taken from 14 patients with Mooren's ulcer were stained immunohistochemically for CD3, CD4, CD8, HLA-DR, CD1 and CD25. RESULT: An aberrant expression of HLA-DR antigen by a large number of kerato-conjunctival epithelial cells and keratocytes in the corneal stroma was found. The CD4+/CD8+ ratio is significantly higher than normal control. CONCLUSION: The aberrant expression of MHC-II antigen in the resident cells at the peripheral cornea and the adjacent conjunctiva, along with a raised local TH/Ts ratio leading to an excessive autoimmune reactivity is possibly the direct cause of Mooren's ulcer.

Adult↗
PubMed1996

[Synthesis of polyfunctional bridging agent-tetrakis (omega-hydroxyproxymethyl) methane and tri (hydroxyproxymethyl) amino methane].

In order to look for the polyfunctional bridging agent. Tetrakis (omega-hydroxyproxymethyl) methane (3) and Tri (omega-hydroxyproxymethyl) aminomethane (4) were prepared from pentaerythritol and trihydroxymethylamino methane respectly. Nine derivatives (5-13) of compounds (3) and (4) were synthesized. The structures of all new compounds (5-13, 15) were confirmed by IR, 1H-NMR and elemental analysis.

Bridged-Ring Compounds↗
PubMed1996

The healing of excimer laser ablated cornea and the effects of corticosteroid.

OBJECTIVE: To investigate the wound healing of the cornea following 193 mm excimer laser photorefractive keratectomy (PRK) and the effects of corticosteroid on it. METHODS: PRK was performed on both eyes of 6 monkeys. Corticosteroid was given to the right eyes, but not to the left ones. At 4 days, 1 week, 2 weeks, 1 month, 3 months and 6 months, corneal pachymetry was examined and the eyes of one monkey were enucleated and the corneas were stained immunohistochemically for collagen type III, type IV and type VII, fibronectin and laminin. RESULTS: The expression of collagen type Vii recovered to the normal linear patter at 1 month. With corticosteroid, the deposition of collagen type III and fibronectin was markedly reduced and the pachymetry of central cornea was closer to the expected value. CONCLUSION: This study suggests that corticosteroid help to minimize the postoperative myopic regression and corneal haze after PRK.

Administration, Topical↗
PubMed1996

[An investigation of a family tree with congenital deficiency in coagulation factor XIII].

In order to study the hereditary trait of a 20-year-old girl with congenital deficiency of coagulation factor XIII and her family tree, the following laboratory tests were done for the propositus and her family members: clot solubility test in 5 mol/L urea, estimation of factor XIII activity, amount of the subunits A and S of factor XIII with rocket electrophoresis. The results showed that the propositus had clinical history of bleeding in umbilical cord and its stump after birth. Her parents are not consanguineously related and have no history suggestive of hemorrhagic diathesis. The propositus has one brother and three sisters. One of her sisters died of bleeding of the umbilical cord after birth, another died at age of two, but the reason of her death is unclear and the remaining siblings are clinically healthy. The propositus had an abnormal urea clot lysis test, but the other family members had normal results. For the propositus factor XIII activity was 0%. A subunit 0% and S subunit 8.2%. Factor XIII activity of her father, her mother and her sister were 25%, 50%, 25% respectively. A subunit 52%, 58%, and 58% respectively and S subunit 66%, 68% and 66% respectively. The results showed that the propositus has a congenital deficiency in coagulation factor XIII, and her parents and sister are in fact carriers.

Adult↗
PubMed1996

[Predictable value of fasting blood glucose level for the incidence of non-insulin-dependent diabetes mellitus].

In order to investigate the predictable value of fasting blood glucose (FBG) level for the incidence of non-insulin-dependent diabetes mellitus (NIDDM), 638 nondiabetic subjects who were investigated in 1986 (including 341 subjects with normal glucose tolerance and 297 subjects with impaired glucose tolerance) were reexamined in 1992. The results showed that the 6-year-incidence of NIDDM was significantly increased with rising of baseline FBG level. After adjusting for age, sex and body mass index (BMI), proportional hazard regression analysis showed that FBG level in impaired glucose tolerance group was positively associated with the development of NIDDM (P = 0.0001). Subjects with mean FBG level of 5.19 mmol/L had a higher risk of developing NIDDM than subjects with mean FBG level of 4.61 mmol/L (RR 2.1, 95% CI 1.19-3.74, P = 0.01). The risk ratio of NIDDM was further increased in the group with mean FBG level of 6.l5 mmol/L (RR = 2.9, 95% CI 1.79-4.59, P = 0.0001). The result indicates that FBG level is an independent risk factor for the development of NIDDM.

Adult↗