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Biomedical subjects

M L Zhang

Publications and source records attributed to M L Zhang.

At least 19 recordsLinked to original sources
PubMed2006

Antisense oligonucleotides targeted against asialoglycoprotein receptor 1 block human hepatitis B virus replication.

Chronic hepatitis B virus (HBV) infection is a major worldwide public health problem. Better therapeutics and treatment strategies are urgently needed because of ineffective clinical treatment. Our previous study showed that asialoglycoprotein receptor 1 (ASGPR1) was upregulated by HBV but downregulated by lamivudine in HepG2.2.15 cells. It has also been reported that ASGPR is a candidate receptor for HBV attachment to hepatocytes. Therefore, as a major subunit of ASGPR, ASGPR1, might be a potential target for anti-HBV drugs. To validate this hypothesis, antisense oligonucleiotides (ASODNs) were used to downregulate ASGPR1 level in HepG2.2.15 cells. By using the MFOLD web server and BLAST searches, five ASODNs theoretically targeting ASGPR1 were selected. After 72 h post-transfection, HBV-DNA level in cell medium were examined by real-time polymerase chain reaction (PCR). Hepatitis B surface antigen (HBsAg) and Hepatitis B e antigen (HBeAg) were detected using enzyme-linked immunosorbent assay (ELISA). ASGPR1 mRNA and protein level were measured by semi-quantitative reverse transcriptase (RT)-PCR and Western blot analysis respectively. The results showed that ASODN2 significantly downregulated ASGPR1 level. It also reduced HBV-DNA, HBsAg and HBeAg level in cell medium as observed with lamivudine. In contrast, the sense sequence and scrambled sequence of ASODN2 had no effect on ASGPR1 and HBV markers in HepG2.2.15 cells. This indicated that ASODN2 could specifically reduce HBV replication in vitro. Additionally, cell proliferation and apoptosis assay suggested that downregulation of ASGPR1 did not affect cell viability. We, therefore, proposed that ASODNs targeted against ASGPR1 could block HBV replication without the influence of other changes, and ASGPR1 could be targeted for anti-HBV drug development.

Antiviral Agents↗
PubMed2004

An autosomal genomic scan for loci linked to type 2 diabetes in northern Han Chinese.

We report the results of a genome-wide scan conducted in 219 individuals from 34 large multiplex nuclear pedigrees from the northern Han Chinese population at an average resolution of about 10 cM. Nonparametric two-point and multipoint linkage analyses were performed to detect evidence of linkage with type 2 diabetes in this study. On chromosome 1 four regions showed evidence of linkage with type 2 diabetes in northern Han Chinese. Of these regions a marker D1S193 (73 cM) showed evidence of linkage (two-point nonparametric linkage 2.409), and another region (around 190 cM) was a replication of several other studies performed in different ethnic populations. Evidences of linkage have been confirmed by typing additional markers (average distance 1-5 cM) flanking these two positive regions on chromosome 1. We also found indication of linkage with type 2 diabetes on chromosomes 2, 10, 12, 18, 20, and 22 by two-point linkage analyses.

Adult↗
PubMed2001

An in vivo reporter system for measuring increased inclusion of exon 7 in SMN2 mRNA: potential therapy of SMA.

Spinal muscular atrophy (SMA) is a degenerative motor neuron disorder resulting from homozygous loss of the SMN1 gene. SMN2, a nearly identical copy gene, is preserved in SMA patients. A single nucleotide difference between SMN1 and SMN2 causes exon 7 skipping in the majority of SMN2 mRNA. Gene therapy through modulation of SMN2 gene transcription in SMA patients may be possible. We constructed a series of SMN mini-genes comprised of SMN exon 6 to exon 8 sequences fused to green fluorescence protein (GFP) or luciferase reporters, to monitor SMN exon 7 splicing. These reporters recapitulated the splicing patterns of the endogenous SMN gene in stable cell lines. The SMN1-luciferase reporter was approximately 3.5-fold more active than SMN2-luciferase and SMN1-GFP intensities were visually distinguishable from SMN2-GFP. We have screened chemical inducers and inhibitors of kinase pathways using stable SMN-reporter lines and found that the phosphatase inhibitor sodium vanadate specifically stimulated exon 7 inclusion within SMN2 mRNAs. This is the first compound identified that can stimulate exon 7 inclusion into transcripts derived from the endogenous SMN2 gene. These results demonstrate that this system can be utilized to identify small molecules that regulate the splicing of SMN exon 7.

Artificial Gene Fusion↗
PubMed1999

Prevention of encephalomyocarditis virus-induced diabetes in mice by inhibition of the tyrosine kinase signalling pathway and subsequent suppression of nitric oxide production in macrophages.

Macrophages comprise the major population of cells infiltrating pancreatic islets during the early stages of infection in DBA/2 mice by the D variant of encephalomyocarditis virus (EMC-D virus). Inactivation of macrophages prior to viral infection almost completely prevents EMC-D virus-induced diabetes. This investigation was initiated to determine whether a tyrosine kinase signalling pathway might be involved in the activation of macrophages by EMC-D virus infection and whether tyrosine kinase inhibitors might, therefore, abrogate EMC-D virus-induced diabetes in vivo. When isolated macrophages were infected with EMC-D virus, inducible nitric oxide synthase mRNA was expressed and nitric oxide was subsequently produced. Treatment of macrophages with the tyrosine kinase inhibitor tyrphostin AG126, but not tyrphostin AG556, prior to EMC-D virus infection blocked the production of nitric oxide. The infection of macrophages with EMC-D virus also resulted in the activation of the mitogen-activated protein kinases (MAPKs) p42(MAPK/ERK2)/p44(MAPK/ERK1), p38(MAPK), and p46/p54(JNK). In accord with the greater potency of AG126 than of AG556 in blocking EMC-D virus-mediated macrophage activation, the incidence of diabetes in EMC-D virus-infected mice treated with AG126 (25%) was much lower than that in AG556-treated (75%) or vehicle-treated (88%) control mice. We conclude that EMC-D virus-induced activation of macrophages resulting in macrophage-mediated beta-cell destruction can be prevented by the inhibition of a tyrosine kinase signalling pathway involved in macrophage activation.

Animals↗
PubMed1999

Absolute requirement of macrophages for the development and activation of beta-cell cytotoxic CD8+ T-cells in T-cell receptor transgenic NOD mice.

The development of autoimmune diabetes in NOD mice results from selective destruction of beta-cells by a T-cell-dependent autoimmune process. However, the mechanisms that control the generation of beta-cell cytotoxic T-cells in vivo are poorly understood. We recently established 8.3-T-cell receptor (TCR)-beta transgenic NOD mice that show a selective acceleration of the recruitment of CD8+ T-cells into the islets of prediabetic animals, resulting in rapid beta-cell destruction and early onset of diabetes. This study was initiated to determine the role of macrophages in the development and activation of diabetogenic CD8+ T-cells in 8.3-TCR-beta transgenic NOD mice. Inactivation of macrophages in these transgenic mice resulted in the complete prevention of diabetes. When splenic T-cells from macrophage-depleted 8.3-TCR-beta transgenic NOD mice were transfused into severe combined immunodeficiency disease (NOD.scid) mice, none of the recipients developed diabetes up to 10 weeks after transfer, while most of the recipients of T-cells from age-matched control 8.3-TCR-beta transgenic NOD mice became diabetic. When intact NOD islets were transplanted under the renal capsule of macrophage-depleted 8.3-TCR-beta transgenic NOD mice, the majority of the grafted islets remained intact, while most of the islets grafted into age-matched, control 8.3-TCR-beta transgenic NOD mice were destroyed within 3 weeks after transplantation. The depletion of macrophages in these mice resulted in a decrease in the Th1 immune response along with an increase in the Th2 immune response because of significant decreases in the expression of macrophage-derived cytokines, particularly interleukin-12, and a decrease in beta-cell-specific T-cell activation, as shown by significant decreases in the expression of Fas ligand (FasL), CD40 ligand (CD40L), and perforin, as compared with control mice. We conclude that macrophages are absolutely required for the development and activation of beta-cell cytotoxic CD8+ T-cells in 8.3-TCR-beta transgenic NOD mice.

Animals↗
PubMed1998

Co-localization of mu-opioid receptor-like immunoreactivity with substance P-LI, calcitonin gene-related peptide-LI and nitric oxide synthase-LI in vagal and glossopharyngeal afferent neurons of the rat.

Co-localization of mu-opioid receptor (MOR)-like immunoreactivity (-LI) with substance P (SP)-LI, calcitonin gene-related peptide (CGRP)-LI and nitric oxide synthase (NOS)-LI in the nodose, petrosal and jugular ganglia was examined in the rat by a double immunofluorescence histochemical method. About 0.6%, 41% and 95% of neurons with MOR-LI, respectively, in the nodose, petrosal and jugular ganglia showed SP-LI; about 2%, 51% and 66% of MOR-like immunoreactive neurons displayed CGRP-LI in the nodose, petrosal and jugular ganglia, respectively. In addition, about 59% of MOR-like immunoreactive neurons in the nodose ganglia displayed NOS-LI, whereas no NOS-LI was detected in the petrosal or jugular ganglion. These data provide evidence for co-localization of MOR-LI with SP-LI, CGRP-LI and NOS-LI in the vagal and glossopharyngeal afferent neurons, and suggest that MOR may regulate the release of SP, CGRP and nitric oxide from the visceral primary afferent terminals in the nucleus of the solitary tract of the rat.

Animals↗
PubMed1998

A potential approach to antifertility vaccine by expression of sperm membrane peptide in Salmonella.

A synthetic oligonucleotide, HSD-2a, encoding a peptide segment of the extracellular domain of a human sperm membrane protein, YWK-II, was inserted by blunt-end ligation at the EcoRV site in the hypervariable, antigenically determinant region IV of Salmonella flagellin gene fliC (d). The recombinant plasmid (pLS408-H1) was transferred into the nonpathogenic aroA live vaccine Salmonella dublin strain SL5928, which is flagellin-negative. Location of the HSD-2a protein on the surface of the flagella was demonstrated by ELISA and by immunogold-labeling electron microscopy using mouse anti-YWK-II antiserum. A 60 kD protein, corresponding to the chimeric flagellin, was isolated from the recombinant S. dublin and found to contain the expressed HSD-2a peptide determined by Western blot analysis using anti-YWK-II antiserum. The Salmonella strain carrying the recombinant plasmid-pLS408-H1 may thus be a potential source of antifertility vaccine.

Amyloid beta-Protein Precursor↗
PubMed1997

Effect on infant mortality of iodination of irrigation water in a severely iodine-deficient area of China.

BACKGROUND: Hotien county in Xinjiang province, China, is an area of severe iodine deficiency and has a high infantmortality rate. We investigated whether iodine replacement through iodination of the irrigation water would decrease infant mortality. METHODS: We added potassium iodate to irrigation water over a 2 to 4 week period beginning in 1992 in certain areas of three townships (Tusala, Long Ru, and Bakechi). Logistic regression analysis was used to compare the odds ratios for infant and neonatal mortality in treated and intreated areas. FINDINGS: The median urinary iodine concentration significantly increased in women of child-bearing age from < 10 micrograms/L to 55 micrograms/L. Infant-mortality rates decreased in the treated areas of Long Ru (mean [SD] 58.2 [4.4] per 1000 births to 28.7 [7.1] per 1000 births), Tusala (47.4 [12.4] per 1000 births to 19.1 [1.5] per 1000 births), and Bakechi (106.2 [9.5] per 1000 births to 57.3 [7.3] per 1000 births). Similar results were also seen for neonatal mortality. On regression analysis iodine treatment and time were significant independent predictors of infant mortality. INTERPRETATION: Iodine supplementation of irrigation water in areas of severe iodine deficiency decreases neonatal and infant mortality. Iodine replacement has probably been an important factor in the national decrease in infant mortality in China.

Adult↗
PubMed1997

Identification and expression of epidermal growth factor gene in mouse testis.

Epidermal growth factor (EGF) is produced primarily by Leydig cells of human testis. Expression of the EGF gene was assessed in mouse testis during the course of sexual maturation by the application of the RT-PCR method and the use of specific oligonucleotide primers. Testis EGF mRNA content increased with the developmental age of the mice, i.e., day 15 < day 30 < day 45 postnatal. The expression of the EGF gene appears to correlate with maturation of the testis and proliferation of Leydig-cells.

Animals↗
PubMed1997

Cyclic AMP induces a relaxation response in the bullfrog Rana catesbeiana, but nitric oxide does not.

Cholecystokinin octapeptide (CCK), acetylcholine (ACh) and ceruletide have been shown to produce contraction in bullfrog (Rana catesbeiana) gallbladder strips. Agents capable of relaxing the bullfrog gallbladder are less numerous. Calcitonin gene-related peptide reduced the amount of both CCK- and ACh-induced tension in bullfrog gallbladder strips. The purpose of this study was to determine whether vasoactive intestinal peptide (VIP), nitric oxide (NO) and the second messengers cyclic GMP or cyclic AMP had any effect on gallbladder motility in the bullfrog. In vitro tension studies using l-NG-nitro-arginine methyl ester, Methylene Blue, sodium nitroprusside and N2,2'-O-dibutyryl guanosine 3',5'-cyclic monophosphate suggested that nitric oxide did not modulate gallbladder motility in the bullfrog gallbladder. Histochemical staining for NADPH diaphorase (nitric oxide synthase) failed to demonstrate nerve fibers containing nitric oxide synthase in the bullfrog gallbladder. In vitro studies demonstrated that VIP had no effect on CCK-induced tension. However, in vitro studies using either 8-bromoadenosine 3',5'-cyclic monophosphate or forskolin demonstrated that both agents relaxed strips precontracted with CCK. The results of this study suggested that, while neither NO nor VIP had a role in modulating bullfrog gallbladder motility, cyclic AMP was capable of modulating bullfrog gallbladder motility.

Animals↗
PubMed1995

Constitutive activation of the thyrotropin receptor by deletion of a portion of the extracellular domain.

Mutations involving the transmembrane domain of the thyrotropin receptor (TSHR) confer constitutive activation of the receptor and can cause human diseases. Naturally occurring activating mutations identified to date are located only in the transmembrane domain of the receptor. We now report a mutant involving the extracellular domain of the TSHR which also shows constitutive activation. This mutation is missing residues 339-367 located in the C-terminal portion of the extracellular domain. When expressed in COS-7 cells, the mutated TSHR (M3B) retained similar TSH binding ability to that of the wild-type receptor. However, the basal cAMP production without TSH stimulation in COS-7 cells transfected with M3B cDNA was significantly higher than that of COS-7 cells with wild-type receptor, indicating that the mutant receptor is constitutively activated. Our results provide new insight into the mechanism of receptor activation.

Animals↗
PubMed1995

Inhibition of thyrocyte iodide uptake by H+K+ ATPase inhibitor, timoprazole.

The inhibitory effect of timoprazole on iodide uptake by cultured thyrocytes was observed using FRTL-5 cells. The inhibition was noticed to be dose dependent and was eliminated completely by rinsing. Timoprazole pretreated with acid had inhibitory effects, but [3H] leucine incorporation experiments indicated that acidified timoprazole inhibited protein synthesis to some degree. In addition, TSH-induced cAMP production was also inhibited by acidified timoprazole. Timoprazole pretreated in a neutral solution did not have any cytotoxic effects on TSH-induced cAMP production or protein synthesis at concentrations less than 1000 microM, suggesting that timoprazole by itself has specific effects on iodide uptake. The absence of any direct interaction of the drug with iodide was confirmed by separation of timoprazole and iodide on a C18 Sep-Pak column. It is concluded that timoprazole by itself could inhibit iodide transport through the thyroid cell membrane. This may provide a useful system in further investigating the mechanism of iodide transport.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

One-stage microneurovascular free abductor hallucis muscle transplantation for reanimation of facial paralysis.

We introduce a new method using abductor hallucis muscle free transplantation for reanimation of the cheek with long-standing facial palsy in six young patients. The muscle is used to reanimate facial palsy because it has many unique advantages: (1) appropriate size and shape of the muscle and adequate bulk, (2) closely parallel alignment and unvaried anatomy of the main vessels and nerve distribution to the muscle, (3) a long neurovascular pedicle, (4) easy surgical isolation of the muscle and its neurovascular pedicle, and (5) no functional deficit after muscle removal. The nerve and muscle grafts can be performed by microneurovascular anastomosis in one surgical procedure. The follow-up period was over 1 year. A satisfactory result was obtained in five of six patients.

Adult↗
PubMed1995

Efficacy of tablet huperzine-A on memory, cognition, and behavior in Alzheimer's disease.

AIM: To evaluate the efficacy and safety of tablet huperzine-A (Hup) in patients with Alzheimer's disease. METHODS: Using multicenter, prospective, double-blind, parallel, placebo controlled and randomized method, 50 patients were administered orally 0.2 mg (4 tablets) Hup and 53 patients were given po 4 tablets of placebo bid for 8 wk. All patients were evaluated with Wechsler memory scale, Hasegawa dementia scale, mini-mental state examination scale, activity of daily living scale, treatment emergency symptom scale, and measured with BP, HR, ECG, EEG, ALT, AKP, BUN, Cr, Hb, WBC, and urine routine. RESULTS: About 58% (29/50) of patients treated with Hup showed improvements in their memory (P < 0.01), cognitive (P < 0.01), and behavioral (P < 0.01 functions. The efficacy of Hup was better than placebo (36%, 19/53) (P < 0.05). No severe side effect was found. CONCLUSION: Hup is a promising drug for symptomatic treatment of Alzheimer's disease.

Aged↗
PubMed1994

Timing of vulnerability of the brain to iodine deficiency in endemic cretinism.

BACKGROUND: Endemic cretinism, caused by severe iodine deficiency during pregnancy, is the world's most common preventable cause of mental retardation. It can be prevented by iodine treatment before conception, but whether it can be prevented or ameliorated by treatment during pregnancy or after delivery is not known. METHODS: In a severely iodine-deficient area of the Xinjiang region of China, we systematically administered iodine to groups of children from birth to three years of age (n = 689) and women at each trimester of pregnancy (n = 295); we then followed the treated children and the babies born to the treated women for two years. We used three independent measures of neural development: the results of the neurologic examination, the head circumference (which correlates with brain weight in the first postnatal year), and indexes of cognitive and motor development. Untreated children one to three years of age, who were studied when first seen, served as control subjects. RESULTS: The prevalence of moderate or severe neurologic abnormalities among the 120 infants whose mothers received iodine in the first or second trimester was 2 percent, as compared with 9 percent among the 752 infants who received iodine during the third trimester (through the treatment of their mothers) or after birth (P = 0.008). The prevalence of microcephaly (defined as a head circumference more than 3 SD below U.S. norms) decreased from 27 percent in the untreated children to 11 percent in the treated children (P = 0.006), and the mean (+/- SD) developmental quotient at two years of age increased (90 +/- 14, vs. 75 +/- 18 in the untreated children; P < 0.001). Treatment in the third trimester of pregnancy or after delivery did not improve neurologic status, but head growth and developmental quotients improved slightly. Treatment during the first trimester, which was technically problematic, improved the neurologic outcome. CONCLUSIONS: Up to the end of the second trimester, iodine treatment protects the fetal brain from the effects of iodine deficiency. Treatment later in pregnancy or after delivery may improve brain growth and developmental achievement slightly, but it does not improve neurologic status.

Brain↗
PubMed1994

Iodination of irrigation water as a method of supplying iodine to a severely iodine-deficient population in Xinjiang, China.

Severe iodine deficiency still occurs in many countries, and causes cretinism and mental impairment. In southern Xinjiang province, China, after usual methods of iodine supplementation had failed, we iodinated irrigation water to increase iodine in soil, crops, animals, and human beings. 5% potassium iodate solution, dripped into an irrigation canal for 12 or 24 days, increased soil iodine 3-fold, and crop and animal iodine 2-fold. Median urinary iodine excretion in children increased from 18 to 49 micrograms/L (two groups of similar age). The cost for iodine was US $0.05 per person per year. Soil iodine remained stable over one winter, and dripping of iodine during the second year (US $0.12 per person per year) resulted in a further 4-fold increase in soil iodine and a 1.8-fold increase in iodine in crops. We conclude that iodination of irrigation water is an advantageous and cost-effective method of supplying iodine in southern Xinjiang, and may be useful in other areas dependent on irrigation.

Agriculture↗