Biomedical subjects

Jun Zhang

Publications and source records attributed to Jun Zhang.

At least 91 records · Page 5Linked to original sources

PubMed2006

VEGF C2578A polymorphism does not contribute to amyotrophic lateral sclerosis susceptibility in sporadic Chinese patients.

A linkage and association of the VEGF (vascular endothelial growth factor) C2578A polymorphism and amyotrophic lateral sclerosis (ALS) has been found in some studies. We analysed the C2578A polymorphism in sporadic ALS patients from a Chinese population. The polymorphism was analysed in 115 patients and 200 healthy individuals by amplifying across position 2705 to 2494 of the promoter region of the VEGF gene. It was found that the frequency of the allele A was 24% in ALS patients and 28% in healthy individuals (p = 0.264). Comparing the background of this polymorphism in healthy individuals between Chinese and Caucasians, significant decreases were found in the frequencies of the A/A genotype and allele A (p(s)<0.001). We concluded that VEGF C2578A polymorphism did not confer a susceptibility to sporadic Chinese ALS patients, which was in disagreement with that reported previously in Caucasian populations and might be ascribed to the different genetic background between Chinese and Caucasians.

Adult↗

PubMed2006

Factors related to successful misoprostol treatment for early pregnancy failure.

OBJECTIVE: To identify potential predictors for treatment success in medical management with misoprostol for early pregnancy failure. METHODS: We conducted a planned secondary analysis of data from a multicenter trial that compared medical and surgical management of early pregnancy failure. Medical management consisted of misoprostol 800 mug vaginally on study day 1, with a repeat dose if indicated on day 3. Women returned on days 3 and 15, and a telephone interview was conducted on day 30. Failure was defined as suction aspiration for any reason within 30 days. Demographic, historical, and outcome variables were included in univariable analyses of success. Multivariable analyses were conducted using clinical site, gestational age, and variables for which the univariable analysis resulted in a P < .1 to determine predictors of overall treatment success and first-dose success. RESULTS: Of the 491 women who received misoprostol, 485 met the criteria for this secondary analysis. Lower abdominal pain or vaginal bleeding within the last 24 hours, Rh-negative blood type, and nulliparity were predictive of overall success. However, only vaginal bleeding within the last 24 hours and parity of 0 or 1 were predictive of first-dose success. Overall success exceeds 92% in women who have localized abdominal pain within the last 24 hours, Rh-negative blood type, or the combination of vaginal bleeding in the past 24 hours and nulliparity. CONCLUSION: Misoprostol treatment for early pregnancy failure is highly successful in select women, primarily those with active bleeding and nulliparity. Clinicians and patients should be aware of these differences when considering misoprostol treatment. LEVEL OF EVIDENCE: II-2.

Abortifacient Agents, Nonsteroidal↗

PubMed2006

Comparison of labor progression between induced and noninduced multiparous women.

OBJECTIVE: The incidence of labor induction is rising rapidly in the United States. Among multiparas, labor is often followed with traditional labor curves derived from noninduced pregnancies. We sought to determine how labor progression of multiparous women who presented in spontaneous labor differed from those who were electively induced with and from those induced without preinduction cervical ripening. METHODS: We analyzed data on all low-risk multiparous women with an elective induction or spontaneous onset of labor between 37(+0) and 40(+6) weeks of gestation from January 2002 to March 2004 at a single institution. The median duration of labor by each centimeter of cervical dilatation and the risk of cesarean delivery were computed for 61 women with preinduction cervical ripening and oxytocin induction, 735 women with oxytocin induction, and 1,885 women with a spontaneous onset of labor. An intracervical Foley catheter was used to ripen the cervix. RESULTS: Those women who experienced electively induced labor without cervical ripening had a shorter active phase of labor than did those admitted in spontaneous labor (99 minutes in induced labor versus 161 minutes in spontaneous labor, P < .001). However, the cesarean delivery rate was elevated in the induction group (3.9% versus 2.3%, P < .05). Women who underwent preinduction cervical ripening also had a shorter active phase than those admitted in spontaneous labor (109 minutes versus 161 minutes, P = .01). CONCLUSION: The pattern of labor progression differs for women with an electively induced labor without cervical ripening compared with those who present with spontaneous onset of labor.

Adult↗

PubMed2006

A pilot study of vaginal flora changes with randomization to cessation of douching.

OBJECTIVES: The objectives of this study were to determine whether women who douche regularly would enter a randomized trial of douching cessation or continuation, whether they would adhere to the assigned behavior, and whether there was a dramatic impact on vaginal flora. GOAL: The goal of this study was to determine the feasibility of a large, definitive trial of douching cessation. STUDY DESIGN: Women who douched at least weekly and who had either bacterial vaginosis or normal flora by Gram stain were assigned at random either to continue douching or to stop for 8 weeks. Vaginal Gram stains were obtained every 7 days from each woman. RESULTS: Forty-eight women were randomized. Those assigned to continue reported douching during 77% of study weeks; those assigned to stop denied douching in 94% of weeks. No dramatic differences in flora were observed between women in the continue versus stop groups. CONCLUSION: A large randomized trial of douching cessation is feasible.

Bacteria↗

PubMed2006

The impact of parity on course of labor in a contemporary population.

BACKGROUND: Few studies have examined in depth the labor progression of multiparas to determine if there is any additional impact of being parous beyond the first birth. The objective of this study was to determine the effect of parity on labor progression in contemporary obstetric practice. METHODS: Our sample consisted of all low-risk women who delivered a term, live-born infant from January 2002 to March 2004 at a single institution in Delaware, United States (n = 5,589). The median duration of labor by each centimeter of cervical dilation was computed for parity = 0 (n = 2,645); parity = 1 (n = 1,839); parity = 2 (n = 750); and parity = 3 + (n = 355). RESULTS: Multiparas had a significantly faster labor progression from 4 to 10 cm (293, 300, and 313 min, respectively, for parity = 1, parity = 2, and parity = 3 +), compared with nulliparas (383 min for parity = 0), as well as a shorter second stage of labor. However, no significant differences were found in duration of the active phase or the second stage of labor among multiparas. CONCLUSIONS: Additional childbearing appears to have no effect of on the progression of labor among multiparous subgroups. The difference in duration of the active phase between nulliparas and multiparas is substantially smaller in a contemporary population.

Adult↗

PubMed2006

Direct targeting of genetically modified tumour cells to Fc gammaRI triggers potent tumour cytotoxicity.

Expression of the type I receptor for Fc domain of immunoglobulin (Ig)G (Fc gammaRI or CD64) is restricted to myeloid effector cells, such as monocytes, macrophages and a subset of dendritic cells. Previous work has indicated a role for Fc gammaRI in antibody-dependent phagocytosis and lysis of tumour cells. We hypothesised that tagging of tumour cells with an anti-Fc gammaRI single chain Fv (sFv) may facilitate targeting to this receptor on effector cells, thereby initiating tumour cytotoxicity. A vector encoding the sFv for an Fc gammaRI-specific antibody (H22), linked to the transmembrane domain of platelet-derived growth factor was constructed. Transfected tumour cells expressed high surface levels of functional H22-sFv, which greatly enhanced susceptibility for phagocytosis and lysis by monocytes and macrophages. The expression of H22-sFv evoked the ability of tumour cells to directly activate monocytes, as evidenced by phosphorylation of mitogen-activated protein kinase and secretion of the inflammatory cytokines interleukin (IL)-1beta, tumour necrosis factor-alpha and IL-6. Moreover, growth of tumour cells in mice expressing H22-sFv was profoundly delayed (or absent) in transgenic mice expressing human Fc gammaRI. These results demonstrated that tumour cells can be readily modified to activate cell effector mechanisms, a strategy that may be useful for in vivo targeting in patients.

Animals↗

PubMed2006

Methodological challenges in studying labour progression in contemporary practice.

In the 1950s, Emanuel Friedman described the first comprehensive method of evaluating labour in clinical practice. In this landmark work, Friedman described the relationship between the duration of labour and cervical dilation as a sigmoid curve and outlined a tool for following labour progression and for identifying abnormal labour. His definitions of labour protraction and arrest continue to be applied in contemporary obstetric practice, although there have been considerable changes since in the clinical management of labour and delivery. This paper provides an overview of Friedman's work, addresses various methodological challenges in studying labour progression, and describes the utility of more advanced statistical methods for studying labour progression, such as survival analysis, compared with other approaches. Additional research that utilises and refines such methods will provide greater insight into labour progression and may assist in updating the diagnostic criteria for labour protraction and arrest disorders in contemporary obstetric practice. Moreover, such detailed information could have important clinical implications towards reducing the rate of primary caesarean delivery in the United States.

Cesarean Section↗

PubMed2006

Engineering of vascular grafts with genetically modified bone marrow mesenchymal stem cells on poly (propylene carbonate) graft.

Bone marrow mesenchymal stem cells (MSCs) have demonstrated their pluripotency to differentiate into different cell lineages and may be an alternative cell source for vascular tissue engineering. The objective of this study is to create small diameter vessels by seeding and culture of genetically modified MSCs onto a synthetic polymer scaffold produced by an electrospinning technique. A tubular scaffold (2 mm in diameter) with a microstructure of nonwoven fibers was produced by electrospinning of poly (propylene carbonate) (PPC). Rat MSCs obtained from bone marrow were expanded in culture and modified with vasculoprotective gene endothelial nitric oxide synthase (eNOS) or marker gene green fluorescent protein (GFP). These MSCs were seeded onto the electrospun fibrous grafts (internal diameter = 2 mm), and cultured in 5% CO(2) at 37 degrees C. The growth of MSCs in the scaffold was analyzed with scanning electron microscopy (SEM) and hematoxylin and eosin (H&E) staining. The gene transfer and transgenic gene expression were examined with fluorescence-activated cell sorting (FACS), immunochemical staining, reverse transcriptase-polymerase chain reaction (RT-PCR), and western blot. The production of nitric oxide (NO) by the engineered vessels was measured with an NO detection kit. Our data showed that the seeded cells integrated with the microfibers of the scaffold to form a three-dimensional cellular network, indicating a favorable interaction between this synthetic PPC scaffold with MSCs. High transduction efficiency was obtained with the use of concentrated retrovirus in the gene transfection of MSCs. The eNOS gene transcripts and protein were detected in the grafts seeded with eNOS-modified MSCs by RT-PCR and immunochemical staining. The amount of NO produced by grafts seeded with eNOS-modified MSCs was comparable to that produced by native blood vessels, and it was significantly higher than that in the grafts seeded with nonmodified MSCs. In summary, the vascular graft produced by culture of eNOS gene-modified MSCs onto the electrospun tubular scaffolds shows promising results in terms of function. The use of MSCs and therapeutic genes in tissue engineering of blood vessels could be helpful in improving vessel regeneration and patency.

Animals↗

PubMed2006

Trends in the rates of resistance of Ureaplasma urealyticum to antibiotics and identification of the mutation site in the quinolone resistance-determining region in Chinese patients.

The resistance of Ureaplasma urealyticum to antibacterials, isolated from 804 patients from the outpatient clinic of the Sir Run Run Shaw Hospital Hangzhou, China, from March to June over six consecutive years (1999-2004) was reviewed. The quinolone resistance-determining region of six strains of U. urealyticum was analyzed. The level of resistance to doxycycline, josamycin, tetracycline, azithromycin, clarithromycin and pristinamycin was below 20% and did not change during the study period. The rate of resistance to fluoroquinolones (ofloxacin, ciprofloxacin) was much greater than these (>50%) and has increased since 1999. The rate of resistance to Erythromycin decreased from 63.9% in 1999 to about 20% from 2000 onwards. The widespread use of fluoroquinolones had led to high resistance rates in U. urealyticum and the emergence of quinolone resistance. Analysis of the gene sequence of topoisomerase IV and DNA gyrase suggested a role for the topoisomerase IV ParE subunit in fluoroquinolone-resistant U. urealyticum.

Anti-Bacterial Agents↗

PubMed2006

Human flavin-containing monooxygenases.

This review summarizes recent information concerning the pharmacological and toxicological significance of the human flavin-containing monooxygenase (FMO, EC 1.14.13.8). The human FMO oxygenates nucleophilic heteroatom-containing chemicals and drugs and generally converts them into harmless, polar, readily excreted metabolites. Sometimes, however, FMO bioactivates chemicals into reactive materials that can cause toxicity. Most of the interindividual differences of FMO are due to genetic variability and allelic variation, and splicing variants may contribute to interindividual and interethnic variability observed for FMO-mediated metabolism. In contrast to cytochrome P450 (CYP), FMO is not easily induced nor readily inhibited, and potential adverse drug-drug interactions are minimized for drugs prominently metabolized by FMO. These properties may provide advantages in drug design and discovery, and by incorporating FMO detoxication pathways into drug candidates, more drug-like materials may be forthcoming. Although exhaustive examples are not available, physiological factors can influence FMO function, and this may have implications for the clinical significance of FMO and a role in human disease.

Disease↗

PubMed2006

Syntheses of Ag, PbSe, and PbTe nanocrystals and their binary self-assembly exploration at low size-ratio.

Nanocrystals of Ag, PbSe, and PbTe were prepared via a high-temperature organic solution approach, respectively. Using a size-selection technique, the size-distribution of each set of nanocrystals could be fine-tuned and finally monodisperse products were achieved. Superlattice structure of binary self-assemblies in low size-ratio were also explored and characterized by transmission electron microscopy. It is realized that a success of achieving binary self-assembly pattern is greatly dependent on several key factors including particle size-distributions, relative concentrations of both components, as well as the size-ratios between Ag and PbSe (or PbTe) nanocrystals.

Lead↗

PubMed2006

Using nanoparticles to enable simultaneous radiation and photodynamic therapies for cancer treatment.

This paper describes research into a new approach to cancer treatment through a combination of radiation and photodynamic therapies. The assumption is that supplementing conventional radiation therapy with photodynamic therapy (PDT) will enable the use of lower doses of radiation. Under this concept, scintillation or persistent luminescence nanoparticles with attached photosensitizers such as porphyrins are used as an in vivo agent for photodynamic therapy. The nanoparticle PDT agents are delivered to the treatment site. Upon exposure to ionizing radiation such as X-rays, the nanoparticles emit scintillation or persistent luminescence, which, in turn, activates the photosensitizers; as a consequence, singlet oxygen (1O2) is produced. Studies have shown that 1O2 can be effective in killing cancer cells. This is the conventional way in which PDT can augment the effectiveness of ionizing radiation. The innovation described in this study involves the use of in vivo luminescent nanoparticles so that an external light source is not required to support PDT. Consequently, application of the therapy can be more localized and the potential of damage to healthy cells is reduced. This new modality will provide an efficient, low-cost approach to PDT while still offering the benefits of augmented radiation therapy at lower doses.

Animals↗

PubMed2006

Serum level of homocysteine is correlated to carotid artery atherosclerosis in Chinese with ischemic stroke.

OBJECTIVES: To investigate the relationship between serum level of homocysteine (Hcy) and carotid artery atheroscleosis (CAA). METHODS: Both sides of the common carotid artery and internal carotid artery in 126 Chinese patients with ischemic stroke were measured by B-mode ultrasound. The patients were divided into groups: normal, A, B, C and D according to the severity of CAAs. With fasting serum, Hcy as well as folate, vitamin B(12) and lipids were detected. The mean +/- SD age was 64 +/- 13 years (range 39-87 years). RESULTS: In a logistic regression model, the Hcy concentrations were associated with an elevated risk of CAAs independent of all traditional risk factors, and when CAAs became severer, the serum Hcy was higher. The levels of the normal group and A, B, C, D groups were 13.22 +/- 6.15 micromol/L, 16.29 +/- 9.81 micromol/l, 19.49 +/- 11.16 micromol/l, 27.21 +/- 17.47 micromol/l, and 24.14 +/- 8.64 micromol/l, respectively. Rank test showed a significant difference between normal and other groups (p<0.05). The levels of folate and vitamin B(12) were negatively correlated with the Hcy concentrations. Spearman correlation coefficient were -0.23 and -0.42 (p<0.05). CONCLUSIONS: Hyperhomocysteinaemia is an independent risk factor of CAAs and the degree of CAAs is highly correlated with the level of Hcy in serum. The causes of hyperhomocysteinemia may be the result from the decrease in folate and vitamin B(12). Clinical trials are now required to evaluate the effect of treatment with these vitamins on the primary and secondary prevention of cerebral vascular diseases.

Adult↗

PubMed2006

Sequential events in ribonuclease A thermal unfolding characterized by two-dimensional infrared correlation spectroscopy.

The conformational changes in the thermal denaturation of bovine pancreatic ribonuclease A was followed with infrared spectra and analyzed by second derivative and two-dimensional correlation techniques. By analyzing the sequential events in each transition stage, the results were consistent with a step-wise thermal denaturation mechanism in which the structural adjustment of the N-terminal and the opening of the central structure of the protein come before the main unfolding process. Non-native turns were found to form along with the unfolding of the native structures. The central region that is composed of some beta-sheet and alpha-helical structures was found to be the most stable part that might form the residual structure at high temperatures.

Circular Dichroism↗

PubMed2006

Endomorphins restored the endothelium-dependent relaxation of the rabbit aorta rings exposed to high D-glucose condition via NO-cGMP pathway.

Rings of rabbit aorta that were both incubated in a high concentration of D-glucose and contracted submaximally by phenylephrine showed significantly decreased endothelium-dependent relaxations induced by acetylcholine. The cGMP production of aorta rings was also reduced. Treatment with endomorphins (1-1000 nmol/L) restored acetylcholine-induced relaxations of aorta rings incubated in high glucose concentrations and increased the cGMP synthesis. Moreover, this effect of endomorphins on endothelium was antagonized by naloxone, and the increase in the production of cGMP was also blocked.

Animals↗

PubMed2006

A novel human osteoblast-derived severe combined immunodeficiency mouse model of bone metastasis.

OBJECT: One of the major difficulties of conducting bone metastasis research is the lack of adequate models for studying the bone-tumor microenvironment. The limitations of current in vivo models include the following: non-human tumor or bone, variable reproducibility, limited supply, and an inability to be easily manipulated. The objective of the present study was to develop a uniform and reproducible model of bone/spine metastasis by utilizing bone derived from human osteoblasts grown subcutaneously in severe combined immunodeficiency (SCID) mice with subsequent introduction of human carcinoma cell lines. METHODS: Human osteoblasts were serially passed in culture and induced to differentiate into mature osteoblasts. They were subsequently loaded on hydroxyapatite-coated collagen sponges and implanted subcutaneously into the SCID mice. After allowing the bone to mature for 8 weeks, tumor cell suspensions were implanted percutaneously into the bone. The bone-tumor complexes were subsequently harvested, decalcified, and prepared for histological examination. CONCLUSIONS: The authors have developed a novel, reproducible SCID mouse model of bone/spine metastasis by using bone derived from human osteoblasts and subsequently introduced human tumor lines. They believe this model will be useful for studying the basic biology of bone metastases.

Animals↗

PubMed2006

[Clinical effect of intraoperative peritoneal hyperthermic chemotherapy for advanced gastric cancer].

OBJECTIVE: To investigate the clinical effect of intraoperative peritoneal hyperthermic chemotherapy (IPHC) for advanced gastric cancer (AGC). METHODS: A total of 118 AGC patients with serosal invasion were enrolled in this study from 1998 to 2001. Among these cases, 96 patients without macroscopic peritoneal metastases were selected for prophylactic study, including 42 cases with IPHC and 54 cases without IPHC as control. Other 22 patients with macroscopic peritoneal metastases were selected for therapeutic study, including 10 cases with IPHC and 12 without IPHC. Postoperative survival rate and peritoneal recurrence were compared. RESULTS: For prophylactic study, the 1, 2 and 4 years survival rates were 85.7%, 81.0% and 63.9% respectively in the patients with IPHC,significantly higher than 77.3%, 61.0% and 50.8% in the patients without IPHC. Cox ratio hazard model revealed that IPHC procedure was an independent prognostic factor. More patients in the control group suffered from peritoneal recurrence than those in IPHC group (34.7% vs 10.3%). For therapeutic study,the median survival period of the patients with IPHC was 10 months, higher than 5 months in the patients without IPHC. The overall 1, 2, 4 year survival rates were 76.9%, 69.2%, 55.2% respectively in all cases with IPHC, higher than 66.2%, 49.7%, 41.4% in the cases without IPHC. CONCLUSION: IPHC procedure can improve the prognosis of AGC patients with serosal invasion, reduce the risk for peritoneal recurrence, and is an independent prognostic factor.

Adult↗

PubMed2006

[Mechanisms of heavy metal cadmium tolerance in plants].

Cadmium (Cd) is a strongly phytotoxic heavy metal, which inhibits plant growth and even leads to plant death. The main symptoms of Cd(2+) toxicity to plants are stunting and chlorosis. Plant has developed some functions for Cd(2+) tolerance, which include cell wall binding, chelation with phytochelatins (PCs), compartmentation of Cd(2+) in vacuole, and enrichment in leaf trichomes. However, Cd(2+) tolerance in plant is more likely involved in an integrated network of multiple response processes than several isolated functions cited above. In the network, the processes of sulfur metabolism, antioxidative response, and Cd(2+) transport across plasma and vacuole membrane in plant are closely related with Cd(2+) tolerance in plant. The processes of sulfur uptake, assimilation and sequential sulfur metabolism in plant respond to Cd(2+) stress. The expression of sulfur transporters with varied affinity was changed in different ways under Cd(2+) stress, and the high expression of ATP sulfurylase (APS) and adenosine 5' phosphosulfate reductase (APR), which may help to keep the supply of S(2-) for cysteine (Cys) synthesis. The efficiency of Cys synthesis may function in Cd(2+) detoxification, and the up-regulated expression of Ser acetyltransferase (SAT) and O-acetyl-ser (thiol)-lyase (OASTL) has been found in some Cd(2+) treated plants. Reduced glutathione (GSH) is an important antioxidant and the precursor of PCs, glutamylcysteine synthetase (GCS) and glutathione synthetase (GS) catalyze GSH synthesis from Cys, overexpression of the two enzymes can improve Cd(2+) tolerance in plant. PCs are more important Cd(2+) chelators than metallothioneins (MTs) in plants, and the expression of phytochelatin synthase (PCS) responds to Cd(2+) stress. Plant antioxidative system also contributes to Cd(2+) tolerance. The antioxidative response to Cd(2+)-induced oxidative stress varies in different plants and tissues and is also Cd(2+) concentration dependent, and the Cd hyperaccumulator plants show strong tolerance to oxidative stress. Some genes encoded metal transporters with Cd(2+) substrate specificity at plasma and vacuole membranes, which have been isolated and characterized in recent years. These genes play critical roles in Cd(2+) translocation, allocation, and compartmentation in plants. Despite the great progresses made in the field in recent years, there are still some issues which need further exploration, such as the detail of signal transduction and the responses of gene regulation to Cd(2+), the rhizosphere activation and root adsorption to soil Cd(2+), Cd(2+) trafficking in xylem and phloem, Cd(2+) translocation to fruit and seed, and the possible presence of a high-affinity Cd(2+) transporter in Cd hyperaccumulators.

Adenosine Triphosphatases↗