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Biomedical subjects

X Zheng

Publications and source records attributed to X Zheng.

At least 163 records · Page 9Linked to original sources
PubMed1999

Differential activity of diethylstilbestrol versus estradiol as neonatal endocrine disruptors in the female hamster (Mesocricetus auratus) reproductive tract.

The synthetic estrogen diethylstilbestrol (DES) is a potent neonatal endocrine disruptor in the hamster. To test the specificity of this phenomenon, newborn animals were treated with 100 microgram of either DES or the natural estrogen, estradiol-17beta (E2). Of the two, neonatal DES exposure caused greater morphological disruption throughout the female reproductive tract in prepubertal animals and in adults that either retained their ovaries or were ovariectomized and then given the same levels of chronic E2 stimulation. In the uterus, a characteristic histopathological profile, including enhancement of both hyperplastic and apoptotic activity, was initiated prepubertally and exclusively in the endometrial epithelial cell compartment from the neonatally DES-treated animals and then was promoted by E2 stimulation during adulthood. Interestingly, apoptotic activity was not detected in an area of endometrial epithelium that progressed to the neoplastic state in a DES-exposed animal. Lastly, chronic estrogen induction of lactoferrin was also restricted to the DES-exposed endometrium. We conclude that 1) DES is more active than E2 as a perinatal endocrine disruptor in the hamster and 2) this experimental system should be generally useful as a means to screen compounds for such activity and then probe their mechanism of action.

Aging↗
PubMed1999

Isolation of ethylene-insensitive soybean mutants that are altered in pathogen susceptibility and gene-for-gene disease resistance

Plants commonly respond to pathogen infection by increasing ethylene production, but it is not clear if this ethylene does more to promote disease susceptibility or disease resistance. Ethylene production and/or responsiveness can be altered by genetic manipulation. The present study used mutagenesis to identify soybean (Glycine max L. Merr.) lines with reduced sensitivity to ethylene. Two new genetic loci were identified, Etr1 and Etr2. Mutants were compared with isogenic wild-type parents for their response to different soybean pathogens. Plant lines with reduced ethylene sensitivity developed similar or less-severe disease symptoms in response to virulent Pseudomonas syringae pv glycinea and Phytophthora sojae, but some of the mutants developed similar or more-severe symptoms in response to Septoria glycines and Rhizoctonia solani. Gene-for-gene resistance against P. syringae expressing avrRpt2 remained effective, but Rps1-k-mediated resistance against P. sojae races 4 and 7 was disrupted in the strong ethylene-insensitive etr1-1 mutant. Rps1-k-mediated resistance against P. sojae race 1 remained effective, suggesting that the Rps1-k locus may encode more than one gene for disease resistance. Overall, our results suggest that reduced ethylene sensitivity can be beneficial against some pathogens but deleterious to resistance against other pathogens.

Journal Article↗
PubMed1999

Direct mecA detection from blood culture bottles by branched-DNA signal amplification.

A branched-DNA (bDNA) signal amplification method was used to detect the mecA gene directly from blood culture broth growing staphylococci. BACTEC blood culture bottles with positive growth indices and containing staphylococcus-like organisms as shown by Gram stain were tested for the presence of the mecA gene. Comparison of test results was done among 225 patients (one blood culture from each patient). Compared with PCR, the sensitivity and specificity of the bDNA method are 100 and 99%, respectively. The bDNA test is carried out in a 96-well format and requires approximately 6 h to perform. Our preliminary results suggest that direct detection of the mecA gene by bDNA signal amplification is (i) sensitive enough to detect mecA directly from blood culture bottles without the requirement for subculture and (ii) as sensitive and specific as the PCR-based method.

Bacteremia↗
PubMed1999

Identical 371-base-pair deletion mutations in the LAT genes of herpes simplex virus type 1 McKrae and 17syn+ result in different in vivo reactivation phenotypes.

The herpes simplex virus type 1 (HSV-1) LAT gene is the only viral gene abundantly transcribed during latency. LAT null mutants created with strains McKrae and 17syn+ are impaired for both in vivo spontaneous and in vivo-induced reactivation. Thus, LAT is essential for efficient in vivo-induced and spontaneous reactivation. Different investigators have studied two LAT mutants containing a StyI-StyI region deletion corresponding to LAT nucleotides 76 to 447. One mutant, dLAT371 (parent strain, McKrae), had parental high frequencies of spontaneous reactivation. In vivo-induced reactivation was not examined. The other mutant, 17DeltaSty (parent strain, 17syn+), had parental frequencies of in vitro reactivation following cocultivation of explanted ganglia but reduced frequencies of in vivo-induced reactivation. Spontaneous reactivation frequency was not reported for 17DeltaSty. These combined results suggested the possibility that in vivo spontaneous reactivation and in vivo-induced reactivation may map to different regions within the LAT domain. We now report that dLAT371 has in vivo-induced reactivation frequencies of the parent and that 17DeltaSty has reduced frequencies of in vivo spontaneous reactivation. Thus, dLAT371 demonstrated the parental phenotype for both in vivo spontaneous and -induced reactivation while the apparently identical 17DeltaSty was impaired for both in vivo spontaneous and -induced reactivation. These results suggest that one or more differences between the genetic backgrounds of McKrae and 17syn+ result in different in vivo reactivation phenotypes of otherwise identical deletion mutations and that McKrae may have compensating sequences sufficient to overcome the loss of the StyI-StyI region of the LAT transcript.

Animals↗
PubMed1999

Treatment delay and reliance on private physicians among patients with sexually transmitted diseases in China.

We examined health-care seeking practices among patients with sexually transmitted diseases (STDs) in south China. In 1995, we recruited a consecutive sample of 939 STD patients attending the STD clinics of the Municipal STD Control Centers of Guangzhou and Shenzhen, 'special economic zones' near Hong Kong. Attending physicians interviewed patients face-to-face using a standard survey questionnaire. Twenty-seven per cent of all subjects had sought treatment elsewhere for their presenting complaints, before visiting a study clinic. The main sources of prior treatment were private physicians followed by public clinics and drugstores. Women were more likely than men to delay in presenting their current symptoms to a study clinic (32% vs 25%, P=0.046). Factors associated with treatment delay differed by gender. Among men, seeking prior treatment from private physicians (OR=3.31; 95% CI=1.70, 6.43), having no urethral discharge (OR=4.00; 95% CI=2.33, 6.85), having engaged in sex trade (OR=1.64; 95% CI=1.03, 2.63), or being a resident in Shenzhen (OR=1.80; 95% CI=1.12, 2.89) were more likely to delay seeking treatment. Among women, only living in Shenzhen (OR=2.86; 95% CI=1.56, 5.25) was associated with treatment delay. Promotion of appropriate health-seeking behaviours and better management of STDs must be a top priority to slow a rapid spread of STD/HIV in China. Health education, improvement of STD care in the public and private sectors, and regulations of unauthorized private physicians, may help with STD control and HIV prevention.

Adult↗
PubMed1999

[The clinical and pathology study of HBV precore mutant infection in chronic HBV patients].

OBJECTIVE: To elucidate the clinical feature, pathological change and IFN therapy of HBV pre-c mutant(1,896 G-->A point mutation). METHODS: Mutation specific PCR was employed for detecting precore mutation from 108 serum and/or liver samples of patients with chronic hepatitis B infection. Liver damage was evaluated with Knodell's histology activity index(HAI) in 46 patients. RESULTS: HBV precore mutant existed popularly in different e systems status, but the detective rate of HBV precore mutant or mutant prevailing over wild type in HBeAb+ group(14.29%, 46.23%) was significantly higher than that in HBeAg+(0%, 6.45%)group. Mutant infection was associated with the severity of liver diseases, the detective rate in severe chronic hepatitis group was significantly higher(13.64%, 40.91%) than that in chronic asympotamatic carriers groupe(0%, 15.62%). 5 precore mutant positive patients with IFN treatment showed either response or nonresponse to IFN therapy. There was no significant difference of liver pathological change between mutant type and wild type infection in patients with mild chronic hepatitis. CONCLUSION: HBV precore mutant infection existed commonly in patients with chronic hepatitis B, despite of the e system status, though it was more prevalent in patients with HBeAb positive. Further study is needed in the pathogenicity and the treatment of HBV precore mutation.

Adolescent↗
PubMed1999

HSV-1 migration in latently infected and naive rabbits after penetrating keratoplasty.

PURPOSE: To investigate the migration of herpes simplex virus type 1 (HSV-1) between latently infected and naive corneal tissues and trigeminal ganglion (TG) in rabbits after penetrating keratoplasty (PKP) and transcorneal epinephrine iontophoresis. METHODS: Two mutants, genetically constructed from HSV-1 strain 17syn+, were used to inoculate rabbit corneas: 17deltaPst, a latency associated transcript (LAT) negative, low-reactivating virus and 17Pr, a high-reactivating, LAT-positive rescuant of 17deltaPst. Latently infected rabbits were given corneal allografts from naive rabbits, and naive rabbits received grafts from latently infected rabbits. Ninety days after PKP, groups of the transplanted rabbits were induced to reactivate by transcorneal epinephrine iontophoresis, but others were not induced. Viral shedding was monitored by tear film cultures. Rabbits were killed 5 days after iontophoresis. Transplanted grafts, recipient corneal rims, and corresponding TG were obtained. Nucleic acids were extracted and amplified for detection of HSV-1 DNA and viral gene transcription. RESULTS: In naive rabbits receiving grafts transplanted from rabbits latently infected with 17Pr (LAT+), 3 of 6 corneal rims contained HSV DNA after induction. In contrast, none of the 5 corneal rims from naive rabbits receiving grafts from rabbits latent with 17deltaPst (LAT-) contained viral DNA. Viral DNA and gene transcripts were detected in 2 of 6 TG from naive rabbits that received grafts from 17Pr (LAT+) latently infected rabbits. In recipient corneal rims and TG of latently infected rabbits receiving grafts from naive rabbits, viral DNA concentration was significantly greater with induced reactivation, compared with the results in noninduced rabbits. The amount of viral DNA in naive grafts transplanted into 17Pr (LAT+) latently infected rabbits was significantly higher with induction than without induction (P = 0.018). More viral DNA and viral gene transcripts were found in tissues from rabbits latently infected with 17Pr (LAT+) than in rabbits latently infected with 17deltaPst (LAT-). CONCLUSIONS: Corneas from latently infected rabbits contain HSV-1 DNA that can replicate after induced reactivation. Viral migration can occur in both anterograde and retrograde directions between the transplanted graft and the recipient corneal rim and TG. The LAT negative HSV-1 construct 17deltaPst has a significantly reduced ability to replicate and migrate.

Animals↗
PubMed1999

[DNase I sensitivity of nucleus and chromatin in six different tissues of old rates].

In order to investigate the mechanism of aging, we studied the DNase I sensitivity of nucleus and chromatin in six different tissue (heart, liver, spleen, lung, kidney and brain of old and weanling wistar rats. The results showed that the DNase I digestive sensitivity levels of nucleus and chromatin in the tissue of the old rats were lower than those of the weanling rats respectively that in the old rats, the DNase I digestive sensitively in the tissue varied, the lowest sensitivity was in brain (P < 0.01); and that in the weanling rats, lowest DNase I digestive sensitivity of nucleus and chromatin was also in the brain, but the difference was not significant.

Aging↗
PubMed1999

The significance of anti-endothelial cell antibodies in patients with lupus nephritis and immunoblotting analysis of the target components.

OBJECTIVE: To investigate the prevalence of anti-endothelial cell antibodies and its possible role in the pathogenesis in lupus nephritis. METHODS: Sera from 58 patients with lupus nephritis were studied. Cellular enzyme linked immunoabsaborbent assay was used to detect anti-endothelial cell antibodies, and immunoblotting technique was performed to determine its specific endothelial target antigens. RESULTS: 36.2% of the patients with lupus nephritis had elevated IgG isotype anti-endothelial cell antibodies. The association was revealed between the presence of anti-endothelial cell antibodies (AECA) and some laboratory and renal biopsy features, such as thrombocytopenia, higher serum IgG level, lower serum C3 level, higher erythrocyte sedimentation rate (ESR), presence of anti-nuclear antibody (ANA), anti-dsDNA antibodies and glomerular thrombosis. Anti-endothelial cell antibodies were consisted of a group of heterogeneous antibodies, and reacted with different endothelial cell antigens which ranged from 12-90 kD in molecular size in immunoblot. A correlation was demonstrated between heavy proteinuria (> 3.5 g/24 hr) and the existence of antibodies against both 27 and 29 kD endothelial cell antigens, an association between the presence of glomerular capillary thrombi and antibody against the 29 kD endothelial cell antigen was also found. CONCLUSIONS: Lupus nephritis patients with anti-endothelial cell antibodies showed a complex autoimmune disorder and clinical disease activity, and the results also provided an indirect evidence that anti-endothelial cell antibodies might contribute to the pathogenesis of lupus nephritis.

Autoantibodies↗
PubMed1999

[An epidemiological survey and treatment of blindness in Zhangqiu city of Shandong province].

OBJECTIVE: An epidemiological survey of blindness was carried out in Zhangqiu city of Shandong province. METHODS: According to stratified random sampling rule, 11,884 persons were chosen as the sample (the sampling fraction is 1.27%) in the city. The WHO grading system for blindness was followed in the survey. RESULTS: The prevalence of blindness was found to be 0.31%, resulting chiefly from cataract (45.95%), glaucoma (24.32%) and vitreous retinal disease (13.51%). 1 016 cases of blindness caused by cataract were operated for restoration of vision, that were accounted for 73.89% of all cataract blindness estimated from the result of the survey. The rate of intraocular lens implantation in the restorative operations was 84.15% (855/1,016). After operation, the corrected vision in 64.47% of the blindness was >or= 1.0, in 21.26% between 0.6 - 0.9, in 10.24% between 0.3 - 0.5, and in 4.03% between 0.05 - 0.2. CONCLUSION: The epidemiological results show that the main cause of blindness is cataract. So it is the key objective for surgical restoration of vision in the prevention of the blindness in later days.

Adolescent↗
PubMed1999

[Primary study of transfusion transmitted virus (TTV) infection in the hepatitis patients and blood donors in Hunan].

To investigate transfusion transmitted virus (TTV) infection in the hepatitis patients and blood donors in Hunan, we used nested polymerase chain reaction (nPCR) assay with primers from TTV genome to detect TTV DNA in seventy clinical hepatitis cases and forty-three blood donors. The results were as follows: TTV DNA was positive in ten of thirty eight patients with hepatitis B(26.3%), and twelve of thirty-two patients with non-A through non-E(37.5%). Elevated transaminase (ALT) was observed in those cases (452 U.L-1 and 582 U.L-1, respectively). On the other hand, TTV DNA was positive in four of forty-three normal blood donors. The data indicate that infectious rates of TTV in hepatitis patients and blood donors in Hunan are similar to those in Japan, and TTV's pathogenicity needs further study.

Blood Donors↗
PubMed1999

[Studies on chemical constituents of Ilex Merr].

OBJECTIVE: To further probe into the chemical composition of Ilex hainanensis. METHOD: Compound isolation was affected on the basis of the EtOAc soluble fraction of the ethanolic extract from the leaves of the plant. RESULT: Four compounds were obtained and by physico-chemical and spectroscopic methods identified as ursolic acid, ilexgenin A, ilexsaponin A1 and beta-sitosterol-3-O-beta-D-glucoside. CONCLUSION: All the four compounds were isolated from the plant for the first time.

Ilex↗
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

[Cochleogram for assessing hair cells and efferent fibers in carboplatin-treated ear].

OBJECTIVE: This paper describes a convenient histochemical technique that allows one to simultaneously assess the cochlear efferent neurons and inner (IHCs) and outer hair cells (OHCs). METHOD: Selective labeling of the sensory cells and efferent fibers was carried out by first labeling the hair cells for dehydrogenase activity and then staining the efferent fibers for acetylcholinesterase activity. Double-labeled specimens were prepared as a surface preparation and counts were made of the number of hair cells and the number of discreate fiber bundles crossing the tunnel of Corti along the entire length of the cochlea. RESULT: The utility of this technique for assessing ototoxic damage was demonstrated by constructing cochleograms showing the percentage of missing hair cells and tunnel-crossing efferent fibers in chinchillas treated with carboplatin. In the region of the cochlea associated with most IHC loss and a part of OHC missing showed by succinate dehydrogenase in the region of hair cells; however, the loss of tunnel-crossing efferent fibers showed by acetylcholinesterase staining was closely correlated with the percentage of OHC loss. But, if only damage the IHC, the efferent fibers showed normal. CONCLUSION: These results suggest that carboplatin damaged efferent systems may be due to the damage of OHC.

Animals↗
PubMed1999

[A computer-aided analysis system for hypertensive retinal image and its clinical application].

With the use of computer image processing technology and microcirculational network analysis technology, we have developed a new system to analyze the outlook of retinal vessles quantitatively. A multimedia structure has been designed for patient's case history file, which includes the basic information of patients, the operating information during sampling and processing patient's retinal image and the result. The system includes image sampling, image displaying, image processing, parameters measuring and analyzing, reports printing and atlas management. Clinical application indicates that the system is useful to hypertension diagnosis.

Aged↗
PubMed1999

[On the biomechanical reasons why children are liable to have fracture in supracondyle of humerus].

With the viewpoint of biomechanics in theory, this paper analyses why children are liable to have fracture in supracondyle of humerus as a result of falling to the ground with the upper limbs propping up the body while adults usually have fracture in the middle or upper part of humerus under the same condition. The focus of discussion is the change of front-inclination in the lower end of humerus in the process of bone maturity from childhood to adulthood.

Adult↗
PubMed1999

[A robust method for automated detection and grading of retinal venous beading in diabetes mellitus].

Diabetes mellitus is a high prevalence disease in the world and retinal vessel changes such as venous beading are common findings in patients suffering from long-standing diabetes. Three methods (1. Combined use of the SED, ROSE, Modified LoG algorithm; 2. Gaussian fitting-based method; 3. Gradient-based method) for detection venous caliber were used in the first processing stage, then the magnitude of fast Fourier transform of variation function of venous caliber was used as a detective index of venous beading. The reliability of the results, justified by their low variability, makes feasible the standardization of quantitative parameters to be used both in the diagnosis and in the prognosis of diabetes, and also allows prospective studies based upon them.

Algorithms↗