Biomedical subjects

Jun Zhang

Publications and source records attributed to Jun Zhang.

At least 289 records · Page 16Linked to original sources

PubMed2004

Effect of pharmacologic preconditioning with tetrandrine on subsequent ischemia/reperfusion injury in rat liver.

The effect of tetrandrine (TET) pretreatment of Wistar rats subjected to warm hepatic ischemia/reperfusion (I/R) was investigated. After 50 minutes of ischemia in the left and median lobes of the liver and 24 hours of reperfusion (I/R group), the rats were killed. The TET+I/R group rats were pretreated with TET (50 mg/kg body weight IP) 30 minutes prior to the onset of ischemia. Blood samples were taken for measurement of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH). Tissue was taken from the ischemic lobes for measurement of superoxide dismutase (SOD), malonyldialdehyde (MDA), and myeloperoxidase (MPO); determination of the wet/dry weight (W/D) ratio; and histologic studies. The results showed that ALT, AST, and LDH levels in serum were increased in the I/R group; tissue MDA generation, MPO activity, and the W/D ratio were also increased, accompanied by decreased SOD activity. The serum ALT, AST, and LDH levels, as well as the tissue MPO level and W/D ratio, were lower in the TET+ I/R group than in the I/R group; and the SOD level was higher in the TET+IR group than in the I/R group. Moreover, the serum ALT and AST, tissue MDA, and W/D ratio in the TET+I/R group were higher, and the SOD was lower than in the sham group. The histologic examination showed protection against liver damage in the TET+I/R group. The results demonstrated that pretreatment with TET could somewhat protect the liver against I/R injury but does not prevent it. The simultaneous decrease of both lipid peroxide generation and polymorphonuclear neutrophil infiltration in the ischemic liver may explain the acquisition of tolerance following administration of TET.

Alanine Transaminase↗

PubMed2004

A randomized trial of saline solution-moistened misoprostol versus dry misoprostol for first-trimester pregnancy failure.

OBJECTIVE: The purpose of this study was to estimate whether the efficacy of treatment with intravaginal misoprostol for first-trimester pregnancy failure is enhanced by the addition of saline solution. STUDY DESIGN: Eighty women with embryonic/fetal death or anembryonic pregnancy were assigned randomly to receive either 800 microg of misoprostol with saline solution (group I, 41 women) or without (group II, 39 women). Treatment was repeated on day 3 if the gestational sac remained. Curettage was performed if the gestational sac remained on day 8 or as necessary during at least 30 days of follow-up. Data were analyzed with the Student t test and the chi(2) or Fisher exact test. RESULTS: By the first follow-up visit, 73% (group I) and 64% (group II) of women passed the gestational sac (P=.38). By the second follow-up visit, expulsion rates were 83% and 87%, respectively (P=.59). Five subjects in each group underwent curettage. CONCLUSION: Misoprostol is effective for the treatment of failed first-trimester pregnancy. The expulsion rate is not improved by adding saline solution.

Abortifacient Agents, Nonsteroidal↗

PubMed2004

The effect of early epidural versus early intravenous analgesia use on labor progression: a natural experiment.

OBJECTIVE: The purpose of this study was to compare the effect of early epidural with the use of early intravenous analgesia on labor progression. STUDY DESIGN: We systematically selected singleton, nulliparous term pregnancies with a spontaneous labor and analgesia placement <or=4 cm who were delivered at a hospital where the rate of epidural analgesia in labor increased from 1% (before) to 84% (after) in 1 year (a natural experiment). In the before period (n=223 pregnancies), 98% of women used intravenous analgesia, and 2% of women used epidural analgesia. In the after period (n=278 pregnancies), 92% of women used epidural analgesia, and 8% of women used intravenous analgesia. The median duration of labor by each centimeter of cervical dilation was computed and used as a measurement of labor progression. RESULTS: After adjustment had been made for confounders, women in the after period had a slower labor progression only from 4 to 5 cm, compared with those women in the before period. Interestingly, the process of labor admission and epidural analgesia placement, rather than analgesia use per se, appeared to explain most of the slowdown. No significant difference in the rest of the active phase was observed between the 2 groups. CONCLUSION: Our data support recent American College of Obstetricians and Gynecologists guidelines that the restraining use of epidural analgesia at <4 cm of cervical dilation is unnecessary.

Adult↗

PubMed2004

Delayed interval delivery and infant survival: a population-based study.

OBJECTIVE: Delaying delivery of the remaining fetus(es) in a multifetal pregnancy is feasible in some cases. However, the impact of this procedure on infant survival is unclear. STUDY DESIGN: We used the US 1995-1998 Matched Multiple Birth File. We identified 200 twin pregnancies in which the first twin was delivered between 17 and 29 weeks of gestation and the second twin was delivered 2 or more days later. We individually matched the delayed deliveries with 374 twin pregnancies in which the second twin was delivered on the same or next calendar day. Perinatal outcomes and infant survival were compared between the delayed and nondelayed twins. RESULTS: Among the 200 pregnancies with delayed delivery, the mean gestational age at first delivery was 23 weeks and the median duration of delay was 6 days (ranging from 2-107 days). One week of delay in delivery was associated with an increase in infant birth weight of 131 g on average (95% CI: 115-147 g). Moreover, 56% of the delayed second twins survived to 1 year of age, whereas only 24% of the nondelayed second twins survived to 1 year of age (P <.001). However, 11% of the second twin in delayed delivery (95% CI: 6%-16%) experienced fetal death before 24 weeks. CONCLUSION: Delayed delivery of the remaining fetus(es) before 30 weeks of gestation for 2 or more days was associated with improved infant survival.

Birth Weight↗

PubMed2004

Distribution and sources of polynuclear aromatic hydrocarbons in Mangrove surficial sediments of Deep Bay, China.

Twelve sediment samples collected from three transects of mangrove swamp of Deep Bay, Shenzhen, China, were determined for polynuclear aromatic hydrocarbons (PAHs). The total PAHs concentrations ranged from 237 to 726 ng g(-1) dry weight, and showed strong correlation with total organic carbon (TOC), clay content and Pb concentrations. The highest PAHs concentrations were found in the samples from mangrove sediments. Overall, PAHs in Deep Bay sediment were lower than those in other developed areas. The biological effect due to PAHs alone in Deep Bay is expected to be low, based on the comparisons of individual and total PAHs concentrations determined in the sediment with those in USEPA sediment quality guidelines. Four and five-ring compounds dominated the PAHs composition pattern profiles. Principal component analysis (PCA) was applied to further investigate the source of PAHs. The PAH sources of Deep Bay mangrove swamp were suggested to be primarily combustion of fossil fuel, especially leaded-gasoline exhaust.

China↗

PubMed2004

RNA interference targeting cathepsin L and Z-like cysteine proteases of Onchocerca volvulus confirmed their essential function during L3 molting.

We describe the successful use of RNA interference (RNAi) to investigate gene function in the human filarial parasite Onchocerca volvulus third-stage larvae (L3). We targeted two specific gene products, the O. volvulus cathepsin L (Ov-CPL) and cathepsin Z-like (Ov-CPZ) cysteine proteases, which were proposed to function during O. volvulus L3 molting. We show that fluorescent-labeled Cy3-dsRNA corresponding to cpl or cpz regions encoding the mature enzymes can enter the larvae. The molting rate of larvae treated overnight with 0.5 mg ml(-1) cpl was reduced by 92% and 86% in comparison to normal control worms. It appeared that although the larvae started the molting process the last stage of molting, ecdysis was inhibited. The effect was gene specific, as larvae that did not molt in the presence of cpl or cpz dsRNA expressed the other cysteine protease, CPZ and CPL, respectively. This was confirmed by immunoelectron microscopy using antibodies directed against each enzyme. Our present study validate conclusively that both enzymes are essential for the molting of O. volvulus L3 to fourth-stage larvae. We also confirmed that the activity of the enzymes is specific to the changes that occur during the molting process on days 1-3, when the separation between the cuticles is in progress. The development of RNAi in O. volvulus L3 could further help study many of the abundant L3 and molting L3 genes identified through the filarial genome project, many of which, although have no attributed function, were identified as vaccine candidates or potential drug targets.

Animals↗

PubMed2004

Dynamic morphology of sutureless cataract wounds--effect of incision angle and location.

OBJECTIVE: Sutureless cataract surgery has been growing in popularity over the last decade. These clear corneal incisions allow for rapid visual recovery after phacoemulsification, but may be associated with an increased risk of endophthalmitis. The purpose of this study was to evaluate the effect of intraocular pressure (IOP), location, and angle of cataract incisions on wound apposition and sealing in postmortem globes. METHODS: This was an ex vivo laboratory investigation of 20 rabbit eyes and 14 human eyes. Self-sealing clear corneal, limbal, and scleral incisions were created and IOP was controlled with an infusion cannula. Incisions were made at a variety of angles. Optical coherence tomography was used to image the incisions in real time as the IOP was varied by raising and lowering the infusion bottle, so as to simulate the variation in IOP occurring with blinking or squeezing of the eye. RESULTS: With each type of incision, optical coherence tomography demonstrated the dynamic nature of cataract wound morphology as IOP was varied. Higher IOPs, in general, were associated with more tightly sealed wounds than lower IOPs, but this varied according to the location and angle of the incisions. More perpendicular incisions, relative to the surface tangent, sealed less well than incisions created at smaller angles at higher levels of IOP; At lower IOPs, the reverse relationship was observed such that more perpendicular incisions sealed less well than smaller incision angles. CONCLUSION: Changes in IOP may result in variable and sometime poor wound apposition in sutureless cataract incisions. The type of incision and angle of the incision may affect the likelihood of inoculation of the aqueous humor with potentially pathogenic bacteria. For each type of incision, there may be a critical angle at which the incision is better able to withstand fluctuations in IOP.

Animals↗

PubMed2004

Preliminarily investigating the polymorphism of self-organized actin filament in vitro by atomic force microscope.

With the atomic force microscope (AFM), we preliminarily investigated the large-scale structure of actin filaments formed in low concentration protein solution (5 microg/ml) via self-organization without the presence of any F-actin dynamic interfering factors (such as phalloidin) in vitro. It was found that the G-actin could be polymerized into ordered filamentous structures with different diameter from the slimmest filament of single F-actin to giant filament in tree-like branched aggregates. The observed polymerized actin filaments, to which our most intense attention was attracted, was discretely distributed and showed obvious polymorphism distinctly different from those in the presence of phalloidin or actin binding proteins (fimbrin, gelsolin, etc.) in previous experiments. Latter structures were mainly composed of single F-actin and/or multifilaments clearly consisting of several single F-actin. The experimental results clearly demonstrated that non-interference with the F-actin intrinsic dynamics in self-organizing could lead to the polymorphism of actin filamentous structures, and further analysis implied that the disturbance of normal F-actin dynamics by many factors could prevent the emergence of structural polymorphism, more often than not, give rise to formation of specific structures instead and different interference would bring about various particular structures under certain conditions.

Actin Cytoskeleton↗

PubMed2004

Vulvovaginal symptoms in women with bacterial vaginosis.

OBJECTIVE: A substantial, but highly variable, percentage of women with bacterial vaginosis are said to be asymptomatic. The purpose of this study was to estimate the prevalence of symptoms among women with bacterial vaginosis compared with women without bacterial vaginosis by direct, explicit, and detailed questioning of these women. METHODS: Women presenting for a routine health care visit at 12 health department clinics in Birmingham, Alabama, were recruited to participate in a longitudinal study of vaginal flora. At the first visit, they underwent a pelvic examination, lower genital tract microbiological evaluation, and an interview that included detailed questions regarding lower genital tract symptoms. The prevalence of symptoms among women with and without bacterial vaginosis (Gram stain score 7 or higher) was compared. RESULTS: Among 2,888 women without gonorrhea, Chlamydia, or trichomonas, 75% of women with and 82% of women without bacterial vaginosis never noted any vaginal odor in the past 6 months (P <.001). The corresponding values were 63% and 65% for never noting vaginal "wetness" (P =.02); 58% and 57% for vaginal discharge (P =.65); 91% and 86% for irritation (P =.004); 88% and 85% for itching (P =.64); and 96% and 94% for dysuria (P =.002), respectively. Cumulatively, 58% of women with bacterial vaginosis noted odor, discharge, and/or wetness in the past 6 months compared with 57% of women without bacterial vaginosis (P =.70). CONCLUSION: The 2 classic symptoms of bacterial vaginosis discharge and odor are each reported by a minority of women with bacterial vaginosis and are only slightly more prevalent than among women without bacterial vaginosis.

Adult↗

PubMed2004

Frequency of douching and risk of bacterial vaginosis in African-American women.

OBJECTIVE: Frequent vaginal douching has been associated with bacterial vaginosis. We investigated whether infrequent douching is also a risk factor for bacterial vaginosis. METHODS: In this cross-sectional study, we recruited 411 African-American women of reproductive age who were visiting gynecologic or family planning clinics of 2 hospitals in New York City from 1999 to 2001. Detailed information on demographic characteristics, feminine hygiene practice, contraceptive use, and reproductive and medical history was collected through in-person interview. Pelvic examinations and laboratory tests on vaginal secretions were performed. Bacterial vaginosis was defined as Gram stain score of 7 or greater. RESULTS: The overall prevalence of bacterial vaginosis in this population was 27%, similar to the national average. Water-vinegar solution was the most common douche. Although one half of the subjects reported douching regularly, only 2% douched frequently (once per week or more). Frequent douching in the past 3 months had a prevalence ratio of bacterial vaginosis of 2.35 (95% confidence interval 0.98-5.63). However, douching less than once per week was not associated with bacterial vaginosis. CONCLUSION: Douching less than once per week, particularly with a water-vinegar douche, is not associated with bacterial vaginosis in this African-American population. LEVEL OF EVIDENCE: III

Adolescent↗

PubMed2004

Maternal prepregnancy overweight and obesity and the pattern of labor progression in term nulliparous women.

OBJECTIVE: To examine the effect of maternal overweight and obesity on labor progression. METHODS: We analyzed data from 612 nulliparous women with a term pregnancy that participated in the Pregnancy, Infection, and Nutrition Study from 1995 to 2002. The median duration of labor by each centimeter of cervical dilation was computed for normal-weight (body mass index [BMI] 19.8-26.0 kg/m2), overweight (BMI 26.1-29.0 kg/m2), and obese (BMI > 29.0 kg/m2) women and used as a measurement of labor progression. RESULTS: After adjusting for maternal height, labor induction, membrane rupture, oxytocin use, epidural analgesia, net maternal weight gain, and fetal size, the median duration of labor from 4 to 10 cm was significantly longer for both overweight and obese women, compared with normal-weight women (7.5, 7.9, and 6.2 hours, respectively). For overweight women, the prolongation was concentrated around 4-6 cm, whereas for obese women, their labor was significantly slower before 7 cm. CONCLUSION: Labor progression in overweight and obese women was significantly slower than that of normal-weight women before 6 cm of cervical dilation. Given that nearly one half of women of childbearing age are either overweight or obese, it is critical to consider differences in labor progression by maternal prepregnancy BMI before additional interventions are performed.

Body Mass Index↗

PubMed2004

Fetal trisomy 21 and maternal preeclampsia.

BACKGROUND: Placental trophoblast shedding into maternal circulation has been hypothesized as a potential cause of preeclampsia. Because pregnancies with a trisomy 21 fetus also have high levels of fetal cells and cell-free fetal DNA in maternal circulation, we examined whether trisomy 21 pregnancies have a higher risk of preeclampsia than euploid pregnancies. METHODS: We used 2 population-based databases. We identified 7763 pregnancies with a singleton trisomy 21-affected fetus and 15,293 matched euploid gestations from the U.S. Natality files for the period 1995-1999. The second database consisted of 665 pregnancies with fetal trisomy 21 and 987 euploid controls in a population-based Down syndrome study in California. In the latter study, women were interviewed by telephone regarding characteristics and pregnancy complications. Gestational hypertension and preeclampsia are the outcomes of this study. RESULTS: The U.S. Natality files showed that in nulliparous women fetal trisomy 21 was associated with a reduced risk of pregnancy-induced hypertension (adjusted relative risk [aRR] = 0.67; 95% confidence interval [CI] = 0.53 to 0.85). Findings from the California study confirmed this association in nulliparous women, and further revealed that the decrease in overall risk of pregnancy-induced hypertension was mainly the result of a large reduction in the risk of preeclampsia (aRR = 0.19; CI = 0.04 to 0.88) rather than in gestational hypertension by itself (0.83; 0.37 to 1.84). Neither dataset showed these effects among multiparous pregnancies. CONCLUSION: Fetal trisomy 21 is associated with a reduced, rather than increased, risk of preeclampsia, specifically in nulliparous women.

Adult↗

PubMed2004

Nonlinear prediction for Gaussian mixture image models.

Prediction is an essential operation in many image processing applications, such as object detection and image and video compression. When the images are modeled as Gaussian, the optimal predictor is linear and easy to obtain. However, image texture and clutter are often non-Gaussian, and, in such cases, optimal predictors are difficult to obtain. In this paper, we derive an optimal predictor for an important class of non-Gaussian image models, the block-based multivariate Gaussian mixture model. This predictor has a special nonlinear structure: it is a linear combination of the neighboring pixels, but the combination coefficients are also functions of the neighboring pixels, not constants. The efficacy of this predictor is demonstrated in object detection experiments where the prediction error image is used to identify "hidden" objects. Experimental results indicate that when the background texture is nonlinear, i.e., with fast-switching gray-level patches, it performs significantly better than the optimal linear predictor.

Algorithms↗

PubMed2004

Isolated oligohydramnios is not associated with adverse perinatal outcomes.

OBJECTIVE: To examine fetal growth and perinatal outcomes in pregnancies with isolated oligohydramnios. DESIGN: A cohort study. SETTING: Multiple clinics and hospitals. POPULATION: Low risk pregnant women. METHODS: We used data from the multicentre clinical trial of Routine Antenatal Diagnostic Imaging with UltraSound (RADIUS), in which 15,151 low risk pregnant women were randomly assigned to the ultrasound screening group or the control group. Women in the screening group underwent sonographic exams at 15-22 and 31-35 weeks of gestation. Both groups could have clinically indicated sonographic exams at any time. MAIN OUTCOME MEASURES: We used changes of fetal weight z-score to assess whether fetal growth was compromised from the diagnosis of oligohydramnios until delivery, using a repeated-measures regression. We used a combined perinatal index as an indicator of adverse perinatal outcome, which consisted of severe perinatal morbidity and mortality. RESULTS: Oligohydramnios (amniotic fluid index < or =5 cm) was diagnosed in 1.5% (113/7617) of women with ultrasound screening compared with 0.8% (57/7534) among the controls. Approximately half of the oligohydramnios cases in the screening group were isolated with no clearly associated factors (e.g. premature rupture of the fetal membranes, congenital anomalies, diabetes, hypertension, postdate and intrauterine growth restriction). Fetal weight centiles in isolated oligohydramnios cases did not change significantly from diagnosis until delivery. Pregnancies with isolated oligohydramnios had perinatal outcomes similar to pregnancies with a normal amniotic fluid index. CONCLUSION: Isolated oligohydramnios is not associated with impaired fetal growth or an increased risk of adverse perinatal outcomes.

Cohort Studies↗

PubMed2004

Alternative processing events in human FMO genes.

In humans, flavin-containing monooxygenase (FMO) functional diversity is determined by the expression of five FMO genes, named FMO1 to FMO5, and their variants. In this study, we systematically analyzed transcripts of FMO1 to FMO5 in different human tissues by reverse-transcription-polymerase chain reaction and identified a large number of splice variants. Exon skipping was the major splicing event observed. Normally spliced transcripts were generally the prominent transcript detected. For FMO1, FMO2, and FMO3, two to three different splice variants were identified, and their corresponding expression was always low in the tissues examined. For FMO5 and particularly for FMO4, more complex alternative splice patterns were observed, with five and seven splice variants detected, respectively. Most identified FMO splice variants either caused a frame-shift or lacked essential functional sites. The corresponding transcripts were therefore incapable of encoding a functional enzyme and were not analyzed further in this study. However, a common in-frame exon 3- (exon 4 for FMO4) deleted variant, leading to the deletion of 63 amino acids, was identified for FMO1, FMO3, FMO4, and FMO5. To examine the functional importance of exon 3-deletion, FMO1, FMO3, FMO4 and the corresponding exon-deleted proteins were expressed as fusion proteins. Activity studies were done with two selective functional FMO substrates, methimazole, and 10-(N,N-dimethylaminopentyl)-2-(trifluoromethyl)phenothiazine and exon 3- (exon 4 for FMO4) deleted FMOs were not able to catalyze the S- and N-oxygenation of these substrates, respectively. It is not clear whether these FMO splice variants can oxygenate other substrates, including those that remain to be discovered.

Alternative Splicing↗

PubMed2004

Interferon regulatory factor 7 is associated with Epstein-Barr virus-transformed central nervous system lymphoma and has oncogenic properties.

Interferon regulatory factor 7 (IRF-7) is implicated in the regulation of Epstein-Barr virus (EBV) latency. EBV transforms primary B cells, and the major EBV oncoprotein, latent membrane protein 1 (LMP-1), is required for the process. LMP-1 both induces the expression of IRF-7 and activates the IRF-7 protein by phosphorylation and nuclear translocation. Here we report that the expression of IRF-7 is increased in EBV-immortalized B lymphocytes compared with that in primary B cells. IRF-7 was phosphorylated and predominantly localized in the nucleus in the immortalized cells. The expression of IRF-7 was detected in 19 of 27 specimens of primary lymphomas of the human central nervous system by immunohistochemical analysis. The association between LMP-1 and IRF-7 was statistically highly significant for these specimens. An appreciable amount of the IRF-7 expressed in lymphoma cells was localized in the nucleus. Furthermore, IRF-7 promoted the anchorage-independent growth of NIH 3T3 cells. LMP-1 and IRF-7 showed additive effects on the growth transformation of NIH 3T3 cells. IRF-7-expressing NIH 3T3 cells formed tumors in athymic mice. Thus, IRF-7 has oncogenic properties and, along with LMP-1, may mediate or potentiate the EBV transformation process in the pathogenesis of EBV-associated lymphomas.

Adult↗

PubMed2004

Divergence function, duality, and convex analysis.

From a smooth, strictly convex function phi: Rn --> R, a parametric family of divergence function Dphi(alpha) may be introduced: [ equation: see text] for x, y epsilon int dom (Phi) subset Rn, and for alpha in R, with Dphi(+/-1) defined through taking the limit of alpha. Each member is shown to induce an alpha-independent Riemannian metric, as well as a pair of dual alpha-connections, which are generally nonflat, except for alpha = +/-1. In the latter case, Dphi(+/-1) reduces to the (nonparametric) Bregman divergence, which is representable using phi and its convex conjugate phi* and becomes the canonical divergence for dually flat spaces (Amari, 1982, 1985; Amari & Nagaoka, 2000). This formulation based on convex analysis naturally extends the informationgeometric interpretation of divergence functions (Eguchi, 1983) to allow the distinction between two different kinds of duality: referential duality (alpha <--> -alpha) and representational duality (phi <--> phi*). When applied to (not necessarily normalized) probability densities, the concept of conjugated representations of densities is introduced, so that +/-alpha-connections defined on probability densities embody both referential and representational duality and are hence themselves bidual. When restricted to a finite-dimensional affine submanifold, the natural parameters of a certain representation of densities and the expectation parameters under its conjugate representation form biorthogonal coordinates. The alpha representation (indexed by beta now, beta epsilon [-1, 1]) is shown to be the only measure-invariant representation. The resulting two-parameter family of divergence functionals D(alpha,beta), (alpha, beta) epsilon [-1, 1] x [-1, 1] induces identical Fisher information but bidual alpha-connection pairs; it reduces in form to Amari's alpha-divergence family when alpha = +/-1 or when beta = 1, but to the family of Jensen difference (Rao, 1987) when beta = -1.

Algorithms↗

PubMed2004

Ordered nano-lslands on (La,Ba)MnO3 thin film surface by self-organization.

Self-organized nanostructures composed of discrete coherent islands were found on La0.67Ba0.33 MnO3 (LBMO) film surfaces. Our results revealed that rippled surface structures on LBMO films appeared during post-annealing at high temperature, and that the step edges of the rippled surfaces offer energetically favorable positions for the nucleation of coherent islands. The rippled surface serves as a template for the arrangement of coherent islands. This provides a new way to prepare ordered surface nanostructures in perovskite oxides without the necessity to employ any preprocessing techniques prior to the growth.

Barium Compounds↗