Search PubMed⌕ Search

Biomedical subjects

Jun Zhang

Publications and source records attributed to Jun Zhang.

At least 361 records · Page 20Linked to original sources
PubMed2003

Protein kinase Cepsilon interacts with and inhibits the permeability transition pore in cardiac mitochondria.

Although functional coupling between protein kinase Cepsilon (PKCepsilon) and mitochondria has been implicated in the genesis of cardioprotection, the signal transduction mechanisms that enable this link and the identities of the mitochondrial proteins modulated by PKCepsilon remain unknown. Based on recent evidence that the mitochondrial permeability transition pore may be involved in ischemia/reperfusion injury, we hypothesized that protein-protein interactions between PKCepsilon and mitochondrial pore components may serve as a signaling mechanism to modulate pore function and thus engender cardioprotection. Coimmunoprecipitation and GST-based affinity pull-down from mouse cardiac mitochondria revealed interaction of PKCepsilon with components of the pore, namely voltage-dependent anion channel (VDAC), adenine nucleotide translocase (ANT), and hexokinase II (HKII). VDAC1, ANT1, and HKII were present in the PKCepsilon complex at approximately 2%, approximately 0.2%, and approximately 1% of their total expression, respectively. Moreover, in vitro studies demonstrated that PKCepsilon can directly bind and phosphorylate VDAC1. Incubation of isolated cardiac mitochondria with recombinant PKCepsilon resulted in a significant inhibition of Ca2+-induced mitochondrial swelling, an index of pore opening. Furthermore, cardiac-specific expression of active PKCepsilon in mice, which is cardioprotective, greatly increased interaction of PKCepsilon with the pore components and inhibited Ca2+-induced pore opening. In contrast, cardiac expression of kinase-inactive PKCepsilon did not affect pore opening. Finally, administration of the pore opener atractyloside significantly attenuated the infarct-sparing effect of PKCepsilon transgenesis. Collectively, these data demonstrate that PKCepsilon forms physical interactions with components of the cardiac mitochondrial pore. This in turn inhibits the pathological function of the pore and contributes to PKCepsilon-induced cardioprotection.

Animals↗
PubMed2003

Induction of bilirubin clearance by the constitutive androstane receptor (CAR).

Bilirubin clearance is one of the numerous important functions of the liver. Defects in this process result in jaundice, which is particularly common in neonates. Elevated bilirubin levels can be decreased by treatment with phenobarbital. Because the nuclear hormone receptor constitutive androstane receptor (CAR) mediates hepatic effects of this xenobiotic inducer, we hypothesized that CAR could be a regulator of bilirubin clearance. Activation of the nuclear hormone receptor CAR increases hepatic expression of each of five components of the bilirubin-clearance pathway. This induction is absent in homozygous CAR null mice but is observed in mice expressing human CAR instead of mouse CAR. Pretreatment with xenobiotic inducers markedly increases the rate of clearance of an exogenous bilirubin load in wild-type but not CAR knockout animals. Bilirubin itself can also activate CAR, and mice lacking CAR are defective in clearing chronically elevated bilirubin levels. Unexpectedly, CAR expression is very low in livers of neonatal mice and humans. We conclude that CAR directs a protective response to elevated bilirubin levels and suggest that a functional deficit of CAR activity may contribute to neonatal jaundice.

Actins↗
PubMed2003

Familial idiopathic scoliosis: evidence of an X-linked susceptibility locus.

STUDY DESIGN: A genomic screen and statistical linkage analysis of a large sample of families with individuals having idiopathic scoliosis was performed. OBJECTIVES: To identify an X-linked susceptibility locus involved in the expression of familial idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: A large sample of families with individuals having idiopathic scoliosis (202 families; 1198 individuals) were diagnosed through physical examination and radiographic criteria, and genomic screening and genetic linkage analyses were performed. METHODS: Model-independent linkage analysis was used to screen genotyping data from 15 X-linked markers in 202 families (1198 individuals). Families were stratified based on the ratio of the likelihood of an X-linked dominant (XLD) inheritance model relative to that of an autosomal dominant (AD) model. Both model-independent and model-dependent linkage analyses were used to identify potential candidate regions. RESULTS: When the entire set of families were analyzed with model-independent methods, no result was significant at the 0.05 level for any of the markers. However, when the families were stratified based on the ratio of the likelihood of the X-linked dominant to autosomal dominant mode of inheritance, results from model-dependent linkage analysis of 15% of the families most likely to have X-linked dominant inheritance showed six adjacent markers with positive lod score values and a maximum lod score of 1.69 (theta = 0.2) at marker GATA172D05. A lod score of 2.23 at this same marker was found in a single family with six affected individuals. CONCLUSION: The results suggest that a region on the X chromosome may be linked to the expression of familial idiopathic scoliosis in a subset of these families.

Alleles↗
PubMed2003

[Inhibition of invasiveness of human mammary carcinoma cell line MDA435 by heparanase antisense oligodeoxynucleotide].

OBJECTIVE: To evaluate the inhibitory effect of heparanase antisense oligodeoxynucleotide (AS-ODN) on the invasiveness of human mammary carcinoma cell line MDA435. METHODS: The AS-ODN complementary to the start codon region of heparanase mRNA and its control, scrambled nonsense oligodeoxynucleotide (NS-ODN) were designed and synthesized and phosphorothioated. The ODNs were embedded in cationic liposome Lipofectin and transfected into MDA435 cells. The total RNAs and proteins were extracted from the cells 48 hours after transfection and then semi-quantitative RT-PCR and Western blotting were performed to evaluate the heparanase gene and protein expression levels respectively. The invasiveness of transfected MDA435 cells were measured quantitatively by Matrigel invasion assays. RESULTS: The heparanase gene and protein expression and invasiveness of MDA435 cells treated with AS-ODN of different final concentrations were significantly decreased compared with that of the controls (P < 0.01). Besides, the inhibitory effects were significantly different between the cells treated with AS-ODN of different concentrations (P < 0.01). The invasiveness inhibition rates were 34.0%, 57.8% and 79.7% at the cells treated with AS-DON of the final concentrations of 0.1 micro mol/L, 0.2 micro mol/L, and 0.4 micro mol/L, respectively. CONCLUSION: Heparanase AS-DON complementary to the start codon region of heparanase mRNA has a significant inhibitory effect on the invasiveness of human mammary carcinoma cell line in a dose-dependent manner.

Antineoplastic Agents↗
PubMed2003

Differential synaptic organization of GABAergic bipolar cells and non-GABAergic (glutamatergic) bipolar cells in the tiger salamander retina.

The synaptic organizations of gamma-aminobutyric acid-immunoreactive (GABA-IR, GABAergic) and non-GABA-IR (non-IR, glutamatergic) bipolar cells in salamander retina were compared by postembedding immunoelectron microscopy. A total of 238 presynaptic bipolar cell synapses were studied; 61 were GABA-IR and 177 were non-IR. Both groups were similar in that (1). they made asymmetrical ribbon synapses as well as asymmetrical non-ribbon synapses; (2). they made ribbon synapses at dyads, triads, and monads; and (3). the vast majority of ribbon synapses ( approximately 90%) were with dyads. The differences were that synapses of GABA-IR bipolar cells had a higher proportion of (1). direct contact with ganglion cells, (2). non-ribbon synapses, (3). output to GABA-IR amacrine cells, and (4). output in sublamina a. Overall, the output of GABA-IR ribbons was equally split between amacrine and ganglion cell processes, whereas for non-IR ribbons, it was approximately 2:1 in favor of amacrine cells. The ribbon:non-ribbon synapse ratio was approximately 1.2:1 (33:28) for GABA-IR but approximately 2:1 (118:59) for non-IR terminals. Thus, GABA-IR bipolar cells made more direct contacts with ganglion cells and used a higher proportion of non-ribbon synapses. GABA-IR dyads were more likely to contact GABA-IR amacrine profiles (52% vs. 38%). Finally, GABA-IR ribbon synapses were more common in sublamina a than sublamina b (2:1), whereas non-IR synapses were equally present in sublaminas a and b. This differential targeting of ganglion cells and amacrine cells in the OFF vs. ON layers indicates a difference in the role of bipolar cells in the generation of receptive field properties, depending on whether or not they use GABA as well as glutamate for their transmitter.

Animals↗
PubMed2003

Study of ethidium bromide effect on dsDNA separation by capillary zone electrophoresis and laser light scattering.

The effect of ethidium bromide (EB) on dsDNA separation was studied by using capillary zone electrophoresis (CZE) and laser light scattering (LLS). By increasing the concentration from 1 to 15 microg/mL, EB showed significant influence on the separation of pBR322 HaeIII in terms of resolution, speed, and signal-over-noise ratio. The physicochemical properties of DNA, such as mobility under electric field, charge-over-size ratio, and hydrodynamic radius, showed two declines, a sharp drop followed by a relaxed decrease, with increasing EB concentration. Such observations could be explained by using two modes of the dye binding process: intercalation and outside binding. The combination of results obtained from CZE and LLS also confirmed the existence of outside binding. Compared with intercalation, outside binding showed a weaker dye concentration dependence in neutralizing the negative charges on the DNA fragments. Static light scattering showed that and of DNA in 1xTris-borate-EDTA (TBE) were increased with increasing EB concentration. / of DNA with dye had a value larger than 1.5, suggesting a random coil conformation.

DNA↗
PubMed2003

Evaluation of antibody-based and nucleic acid-based assays for diagnosis of hepatitis E virus infection in a rhesus monkey model.

We have evaluated four hepatitis E virus (HEV) specific antibody assays, using sequential samples taken from 86 rhesus monkeys at intervals for up to 86 weeks after they had been infected with different doses of HEV. The animals are a common experimental model of hepatitis E. The large collection of sequential samples used avoids uncertainties encountered in previous studies regarding the precise infection status of study subjects and minimizes bias due to the individuality of response to infection. One assay (YES IgG) was produced with synthetic peptides; the others (E2 IgM, E2 IgG, and GL IgG) were produced with recombinant antigens. The results were compared with the viral RNA contents of the serum and stool samples and the occurrence of these virological and immunological markers in the course of the infection was temporally related to the development of hepatitis. Diagnostic utility of the markers was assessed according to their response rates and prevalence at different times in the course of infection. All the animals produced E2 IgG and developed viremia and all but one also produced E2 IgM and excreted the virus in stool, whereas response rates for the other antibodies were lower and decreased with virus dose. Hepatitis occurred over a period of 4 weeks between 3 and 7 weeks after infection. Virological activity occurred mainly during the incubation period and the prevalence of viral markers declined rapidly after the onset of hepatitis. Production of the E2 antibodies immediately preceded the onset of hepatitis, and this was followed about one week later by production of the other antibodies. Seroprevalence E2 IgM reached a peak value 3 weeks after the onset of hepatitis, whereas seroprevalence of GL IgG and YES IgG peaked after the disease had subsided. E2 IgG persisted in all animals for the entire duration of the experiment of up to 86 weeks and possibly beyond and, thus, can serve as a useful epidemiological marker of HEV infection.

Animals↗
PubMed2003

Platelet adhesive resistance of segmented polyurethane film surface-grafted with vinyl benzyl sulfo monomer of ammonium zwitterions.

Platelet from human plasma adhered on the segmented poly(ether urethane) (SPEU) film grafted with N,N-dimethyl-N-(p-vinylbenyl)-N-(3-sulfopropyl) ammonium (DMVSA) was studied. SPEU films were hydroxylated by potassium peroxosulfate (KPS) and then grafted with DMVSA using ceric ammonium nitrate (CAN) as initiator. The mixing time of hydroxylated SPEU/CAN and the monomer concentration effect on graft polymerization yield were determined by ATR-FTIR. Surface analysis of the grafted films by ATR-FTIR and ESCA confirmed that DMVSA was successfully grafted onto the SPEU film surface. The grafted film possessed a relatively hydrophilic surface, as revealed by water contact angle measurement. The improved blood compatibility of the grafted films was preliminarily evaluated by a platelet-rich plasma adhesion study and scanning electron microscopy, using original SPEU and hydroxylated SPEU films as the controls. The results showed that platelet attachment was decreased greatly on the segmented polyurethane films grafted with DMVSA. This kind of new biomaterials grafted with sulfo ammonium zwitterionic monomers might have potential for biomedical applications.

Blood Platelets↗
PubMed2003

Dynamic morphology of clear corneal cataract incisions.

OBJECTIVE: Clear corneal cataract incisions without sutures allow for rapid visual rehabilitation after phacoemulsification but might be associated with an increased risk of postoperative infection. The goal of this study was to examine in vitro dynamic changes in unhealed clear corneal cataract incisions that might adversely affect the risk of intraocular infection. DESIGN: Laboratory investigation. METHODS: Self-sealing clear corneal incisions were created in cadaveric human and rabbit eyes, and intraocular pressure was controlled with an infusion cannula. Incisions were imaged in real time using optical coherence tomography as intraocular pressure was varied. Using an artificial anterior chamber, India ink was applied to the surface of cadaveric human corneas with clear corneal incisions to detect possible flow of surface fluid along the incision. Intraocular pressure was varied by raising and lowering the infusion bottle so as to simulate the variation in intraocular pressure that would occur with successive blinks. RESULTS: Optical coherence tomography demonstrated variation of corneal wound morphology in response to changes in intraocular pressure. Higher intraocular pressures were associated with close apposition of the wound edges, with no tendency for wound leakage. At low intraocular pressures, however, wound edges tended to gape, starting at the internal aspect of the wound. One incision opened along the entire length, allowing fluid flow across the cornea. Histologic examination revealed India ink particles in all incisions for up to three fourths of the length of the wound. CONCLUSIONS: Transient reduction of intraocular pressure might result in poor wound apposition in clear corneal incisions, with the potential for fluid flow across the cornea and into the anterior chamber, with the attendant risk of endophthalmitis.

Animals↗
PubMed2003

Microtubule-dependent transport of secretory vesicles in RBL-2H3 cells.

Antigen-mediated activation of mast cells results in Ca2+-dependent exocytosis of preformed mediators of the inflammatory response. To investigate the role of secretory vesicle motility in this response, we have performed time-lapse confocal microscopy on RBL-2H3 cells transfected with a green fluorescent protein-Fas ligand fusion protein (GFP-FasL). Green fluorescent protein-labeled vesicles exhibit rapid, bidirectional movement in both resting and activated cells and can be localized adjacent to microtubules. Colchicine treatment inhibits the motility of secretory vesicles as measured by fluorescence recovery after photobleaching (FRAP). Colchicine also inhibits both the extent and the rate of exocytosis triggered by receptor activation or by Ca2+ ionophore, demonstrating that microtubule-dependent movement of secretory vesicles plays an important role in the exocytic response.

Animals↗
PubMed2003

Severe maternal morbidity associated with hypertensive disorders in pregnancy in the United States.

OBJECTIVES: This study was to report the incidence of severe maternal morbidity associated with hypertensive disorders of pregnancy in the United States. STUDY DESIGN: We used data from the National Hospital Discharge Survey, a nationally representative sample of discharge records, from 1988 to 1997. The database consisted of approximately 300,000 deliveries, which represented 39 million births during the 10-year period. RESULTS: The overall incidence of hypertensive disorders in pregnancy was 5.9% [95% confidence interval (CI): 5.2 to 6.5%]. Eclampsia was reported at 1.0 per 1,000 deliveries (95% CI: 0.8 to 1.2). The incidence of eclampsia, severe preeclampsia, and superimposed preeclampsia remained unchanged during the 10-year period. Women with preeclampsia and eclampsia had a 3- to 25-fold increased risk of severe complications, such as abruptio placentae, thrombocytopenia, disseminated intravascular coagulation, pulmonary edema, and aspiration pneumonia. More than half of women with preeclampsia and eclampsia had cesarean delivery. African American women not only had higher incidence of hypertensive disorders in pregnancy but also tended to have a greater risk for most severe complications. Preeclamptic and eclamptic women younger than 20 years or older than 35 years had substantially higher morbidity. CONCLUSION: Preeclampsia and eclampsia carry a high risk for severe maternal morbidity. Compared to Caucasians, African Americans have higher incidence of hypertensive disorders in pregnancy and suffer from more severe complications.

Adolescent↗
PubMed2003

Accumulation of cytoplasmic dynein and dynactin at microtubule plus ends in Aspergillus nidulans is kinesin dependent.

The mechanism(s) by which microtubule plus-end tracking proteins are targeted is unknown. In the filamentous fungus Aspergillus nidulans, both cytoplasmic dynein and NUDF, the homolog of the LIS1 protein, localize to microtubule plus ends as comet-like structures. Herein, we show that NUDM, the p150 subunit of dynactin, also forms dynamic comet-like structures at microtubule plus ends. By examining proteins tagged with green fluorescent protein in different loss-of-function mutants, we demonstrate that dynactin and cytoplasmic dynein require each other for microtubule plus-end accumulation, and the presence of cytoplasmic dynein is also important for NUDF's plus-end accumulation. Interestingly, deletion of NUDF increases the overall accumulation of dynein and dynactin at plus ends, suggesting that NUDF may facilitate minus-end-directed dynein movement. Finally, we demonstrate that a conventional kinesin, KINA, is required for the microtubule plus-end accumulation of cytoplasmic dynein and dynactin, but not of NUDF.

Aspergillus nidulans↗
PubMed2003

Deleterious mutations in the flavin-containing monooxygenase 3 (FMO3) gene causing trimethylaminuria.

The primary genetic form of trimethylaminuria (TMAU) is caused by inherited defects in the flavin-containing monooxygenase 3 (FMO3) gene. Defective FMO3 has a decreased ability to catalyze the N-oxygenation of the dietary-derived malodourous amine, trimethylamine. We report two novel deleterious mutations identified in two unrelated individuals affected by the disorder. Sequence analysis of the FMO3 coding exons amplified from genomic DNA revealed that the mutation from individual 1 was heterozygous for a G>A missense mutation in exon 2 of the FMO3 gene. The mutation changed a GAG encoding Glu at codon 32 to AAG encoding Lys. Wild-type and mutant E32K FMO3 were expressed in Escherichia coli as maltose binding-fusion proteins and assayed for their ability to catalyze oxygenation of various FMO3 substrates. The results showed that the E32K mutation abrogated the catalytic activity of the enzyme. Individual 2 was identified as heterozygous for the P153L mutation. In addition, individual 2 was also heterozygous for a novel single nucleotide deletion of A191 in exon 3 at codon 64. The deletion resulted in a frame shift and caused premature termination of the FMO3 gene immediately after codon 65. Family pedigree analysis revealed that the P153L and the deletion mutation were carried on different alleles for this individual. Therefore, both alleles of the FMO3 gene for individual 2 were affected by mutations abolishing the catalytic activity of the enzyme, explaining the severe TMAU condition. The two deleterious mutations reported herein were rare mutations with estimated allelic frequencies of less than 1%.

Amino Acid Sequence↗
PubMed2003

Induction of multidrug resistance protein 3 (mrp3) in vivo is independent of constitutive androstane receptor.

We previously demonstrated that multidrug resistance protein 3 (Mrp3/ABCC3) is induced in rat liver by phenobarbital (PB) and several other microsomal enzyme inducers that induce cytochrome P450 2B (CYP2B). CYP2B is induced by constitutive androstane receptor (CAR)-retinoid X receptor (RXR) heterodimer binding to a phenobarbital-responsive promoter element in the CYP2B promoter. Hepatic mRNA levels of CYP2B and Mrp3 were measured in three models of altered CAR activity to determine whether CAR is also involved in the induction of Mrp3. In Wistar Kyoto rats, where males express higher CAR protein levels than females, the induction of CYP2B1/2 was significantly higher in males than in females by PB, diallyl sulfide, and trans-stilbene oxide but not oltipraz. Mrp3 was induced by each of these treatments, but in contrast to CYP2B1/2, to a similar magnitude in males and females. In male hepatocyte-specific RXRalpha-/- mice, CYP2B10 was not induced by diallyl sulfide or oltipraz but remained inducible by PB and trans-stilbene oxide after considering the decrease in basal CYP2B10 expression. Mrp3, however, was induced by PB, diallyl sulfide, trans-stilbene oxide and oltipraz in both wild-type and RXRalpha-/- mice. Additionally, constitutive expression of Mrp3 was significantly reduced in RXRalpha-/- mice. In CAR-/- mice, the robust induction of CYP2B10 by PB was completely absent. However, Mrp3 was equally induced both in wild-type and CAR-/- mice by PB. These data clearly demonstrate that induction of hepatic Mrp3 by PB and other microsomal enzyme inducers is CAR-independent and implies a role for RXRalpha in the constitutive expression of Mrp3.

Animals↗
PubMed2003

Two new polymorphisms of the FMO3 gene in Caucasian and African-American populations: comparative genetic and functional studies.

To characterize the contribution of the human flavin-containing monooxygenase form 3 (FMO3) in the metabolism and disposition of drugs and xenobiotics, we determined the single nucleotide polymorphisms in the coding region and adjacent splice junctions of FMO3 in 134 African Americans and 120 Caucasians from the United States. In the regions examined, DNA resequencing or high throughput MassEXTEND studies coupled with mass spectrometric genotyping showed that 12 sites of variation were present. Three variants encoding synonymous mutations and four polymorphisms were observed in the noncoding region. Another three variants, Lys158-FMO3, Met257-FMO3 and Gly308-FMO3, previously reported in similar populations, were prominent polymorphisms. Two new polymorphisms, His132-FMO3 and Pro360-FMO3, were identified in this study. Both variants were found only in African Americans. To evaluate the effect of the amino acid substitutions on the function of FMO3, each amino acid substitution was introduced by site-directed mutagenesis into a wild-type FMO3 cDNA. Selective functional activity was studied with methimazole, trimethylamine, and 10-(N,N-dimethylaminopentyl)-2-(trifluoromethyl) phenothiazine. Both His132-FMO3 and Pro360-FMO3 variants were able to metabolize the substrates examined. Compared with wild-type FMO3, the His132-FMO3 was less catalytically efficient. The His132-FMO3 variant moderately altered the catalytic efficiency of FMO3 (decrease of 30%, 60% and 6% with methimazole, trimethylamine and 10-(N,N-dimethylaminopentyl)-2-(trifluoromethyl)phenothiazine, respectively). The Pro360-FMO3 variant was more catalytically efficient than wild-type FMO3. Pro360-FMO3 oxygenated methimazole, trimethylamine and 10-(N,N-dimethylaminopentyl)-2-(trifluoromethyl)phenothiazine, respectively, 3-, 5- and 2-fold more efficiently than wild-type FMO3. Based on the functional activity of the variant FMO3 enzymes, it is likely that population differences exist for compounds primarily metabolized by FMO3.

Adult↗