Biomedical subjects

Kai Zhang

Publications and source records attributed to Kai Zhang.

At least 109 records · Page 6Linked to original sources

PubMed2003

Separation of peptides by pressurized capillary electrochromatography.

A pressurized electrochromatography (pCEC) instrument with gradient capability was used in this work for separation of peptides. Three separation modes, namely, pCEC, high-performance liquid chromatography and capillary electrophoresiscan be carried out with the instrument. In pCEC mode, the mobile phase is driven by both electroosmotic flow and pressurized flow, facilitating fine-tuning in selectivity of neutral and charged species. A continuous gradient elution can be carried out conveniently on this instrument, which demonstrates that it is more powerful than isocratic pCEC for separation of complicated samples. The effects of applied voltage, supplementary pressure and ion-pairing agents on separation of peptides in gradient pCEC were investigated. The effects of flow-rate of the pump and the volume of the mixer on resolution were also evaluated.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed2003

Hospitalisation, care plans and not for resuscitation orders in older people in the last year of life.

BACKGROUND: over 60% of older people have at least one admission to hospital in their last year of life, with the majority of people having multiple admissions. In Bankstown, New South Wales, Australia, we have a diverse ethnic and cultural population. We were interested in bed utilisation, documentation, and follow through of "care plans" as well as "not for resuscitation" orders in the last year of life of the older people in our area. METHODS: we reviewed and collected data from the medical records of patients over 65 years of age who died in our hospital. Reviewers included a medical registrar, a research officer and two geriatricians. We collected a wide range of information pertaining to the 12 months before death. This included demographics, chronic illnesses, geriatric syndromes, number of admissions, bed days, care plans, and not for resuscitation orders as well as other relevant data. RESULTS: 110 patients' records were reviewed. The mean age was 80 years and 31% were from a non English-speaking background. The average number of admissions was 2.4 and the average number of bed days in the last year of life was 25. Sixty-one of the patients had a care plan and a not for resuscitation order, 91% of which were written shortly before death. Using bi-variate analysis of old age (over 80), number of chronic illnesses, or geriatric syndromes present, the number of bed days was positively correlated to care plan and not for resuscitation orders. Logistic multivariate analysis of chronic illnesses revealed that stroke (P=0.024) as well as stroke and fracture (P=0.008) were strongly correlated with care plan and not for resuscitation orders. Only 8 patients had an advanced care plan documented prior to last admission. When advanced care plans were documented, they were generally clearly written and followed through appropriately (7 out of 8). CONCLUSION: this study showed that in our diverse population there were multiple admissions and utilisation of hospital beds for older people in their last year of life. Care plans and not for resuscitation orders were rarely documented prior to last admission. However, when advanced care plans were done, they were usually well documented and followed through appropriately.

Aged↗

PubMed2003

Effects of odorants on the hypothalamic-pituitary-adrenal axis and interleukin-6 (IL-6) and IL-6 receptor mRNA expression in rat hypothalamus after restraint stress.

We recently reported that stress alters interleukin (IL)-6 and IL-6 receptor (IL-6R) mRNA levels in the hypothalamus. Odorants are reported to exert anti-stress effects. The aim of our study was to determine the effects of odorants on IL-6 and IL-6R mRNA expression in the hypothalamus, using reverse transcriptase-polymerase chain reaction and on serum levels of adrenocorticotropic hormone (ACTH) and corticosterone in rats exposed to stress. Control rats were not exposed to stress; test control rats were exposed to 4 h stress then immediately killed. In other groups, rats were exposed to the same stress followed by 30 min exposure air, dimethoxymethylbenzene (DMMB), or citralva. In the air group, IL-6 and IL-6R mRNA levels were significantly reduced and serum levels of ACTH and corticosterone significantly increased relative to the control. Exposure to DMMB significantly augmented IL-6 mRNA expression but restored that of IL-6R mRNA, did not change serum corticosterone level relative to that of the air group and significantly reduced ACTH. In comparison, citralva restored the expression of IL-6 and IL-6R mRNAs and significantly increased serum ACTH and corticosterone levels. Our results indicate that citralva enhances stress-induced activation of the hypothalamic-pituitary-adrenal axis by corticotropin-releasing hormone (CRH)-mediated stimulation of IL-6, while DMMB enhances the beneficial action of IL-6 without affecting CRH.

Animals↗

PubMed2003

Pax-6 activates endogenous proglucagon gene expression in the rodent gastrointestinal epithelium.

The proglucagon gene encodes pancreatic glucagon and the glucagon-like peptides, which exert diverse effects on nutrient absorption and assimilation. The therapeutic potential of glucagon-like peptide-1 (GLP-1) has fostered interest in development of cellular engineering approaches to augment endogenous intestinal-derived GLP-1 for the treatment of type 2 diabetes. We have used adenovirus technology to examine the potential roles of the transcription factors Cdx-2/3 and Pax-6 as activators of endogenous proglucagon gene expression in enteroendocrine cell lines and in nontransformed rat intestinal cells. Adenoviral-expressed Cdx-2/3 and Pax-6 activated proglucagon promoter-luciferase activity in baby hamster kidney (BHK) fibroblasts, HEK 293 cells, and enteroendocrine cell lines. Pax-6, but not Cdx-2/3, induced expression of the endogenous proglucagon gene in enteroendocrine cell lines, but not in heterologous fibroblasts. Furthermore, transduction of primary rat intestinal cell cultures in vitro, or the rat colonic epithelium in vivo, with Ad-Pax-6 activated endogenous proglucagon gene expression. These data demonstrate that Pax-6, but not Cdx-2/3, is capable of activating the endogenous proglucagon gene in both immortalized enteroendocrine cells and the nontransformed intestinal epithelium in vivo.

Animals↗

PubMed2003

Genetic changes and expression of the mannose 6-phosphate/insulin-like growth factor II receptor gene in human hepatitis B virus-associated hepatocellular carcinoma.

It was reported that 60-70% of hepatitis B virus (HBV)-negative hepatocellular carcinoma (HCC) had loss of heterozygosity (LOH) at the mannose 6-phosphate/insulin-like growth factor II receptor (M6P/IGF2R) locus and this gene was mutated in 55% of these patients with LOH. In this study, genomic DNA from 29 pairs of HBV-positive HCC and corresponding non-tumor tissues was used to analyze LOH at the M6P/IGF2R locus and single deoxyguanosine deletion in this gene by PCR. Total RNA from 19 of the 29 patients was utilized to determine a 192 bp insert in the M6P/IGF2R mRNA and expression of this gene by RT-PCR. Twenty-eight of 29 (97%) HBV-positive HCC were found to be informative at the M6P/IGF2R locus but LOH at this region was only detected in 4/28 (14%) informative patients. Neither single deoxyguanosine deletion in this gene nor 192 bp insert in its mRNA occurred in these patients. Compared with corresponding non-tumor tissues, expression of the M6P/IGF2R mRNA was decreased in 13/19 (68%) HBV-positive HCC tissues, suggesting that M6P/IGF2R may be involved in HBV-associated hepatocarcinogenesis by the regulation of its expression level. In the development of HBV-associated HCC, M6P/IGF2R mutation may not be a major agent.

Adult↗

PubMed2003

[Etiology and management of persistent hematospermia: a pilot study].

OBJECTIVES: To study the etiology of persistent hematospermia and to evaluate the efficacy of transrectal ultrasonography (TRUS)-guided transperineal needle aspiration and irrigation for diagnosis and treatment of persistent hematospermia. METHODS: Twelve patients were included in the study, with a mean age of (36.4 +/- 10.8) years old, and a mean duration of the disease of (13.9 +/- 6.4) months. After the expressed prostatic secretion (EPS) by prostatic massage was cultured, patients with recurrent hematospermia received TRUS-guided transperineal needle aspiration for seminal vesicle fluid (SVF), which was sent for bacteriological and cytological examination. If the EPS culture were positive, certain antibiotics according to the drug sensitivity assay were injected into the abnormal seminal vesicle(s) via TRUS-guided transperineal needle puncture. The treatment would be repeated one month later if the patients still had hematospermia. The patients were followed up every three months. RESULTS: Abnormal images were found in left seminal vesicle (SV) in 4 cases, right in 3 cases, bilateral in 2 cases, and no abnormal findings in 3 cases. The abnormal findings included: 7 cases of SV and/or ejaculatory duct dilation, 3 cases of thickening SV wall, 3 cases of calcification or calculi of SV, and 1 case of Müllerian duct cyst. SVF cultures were positive in 7 cases: methicillin-resistant Staphylococcus aureus (MRSA) 4 cases, methicillin-resistant coagulase-negative Staphylococcus (MRCNS), E. Coli, Proteus mirabilis 1 case, respectively. In five of these 7 cases, bacteriological cultures of SVF and EPS showed the same results. All patients were treated by TRUS-guided transperineal injection of certain antibiotics into SV. Seven cases were injected once, 5 cases twice. The mean follow-up period of 10 patients was (16.7 +/- 5.9) months. Hematospermia disappeared in 6 cases. CONCLUSIONS: SV infection of bacteria, especially infection of the drug resistant strains was one of the main causes of persistent hematospermia. The difficulties in treatment of persistent hematospermia were due to infection of drug resistant bacteria, calcification or calculi of SV, obstruction of ejaculatory duct. TRUS-guided transperineal aspiration of SVF was helpful to the etiologic diagnosis of persistent hematospermia.

Adult↗

PubMed2003

[An experimental study of the effects of profenofos on antioxidase in rabbits].

In order to explore the effects of superoxide dismutase(SOD), catalase(CAT), glutathione-peroxidase (GSH-Px) in rabbits exposed by profenofos and its meaning. 18 rabbits were divided into three groups randomly: A group (high-dose group), B group(low-dose group), C group(control group), each group including 6 rabbits. The activities of SOD, CAT, GSH-Px in plasma, and cholinesterase(ChE) in blood were measured in different exposure period. The results showed that activities of SOD, CAT and GSH-Px increased, ChE decreased markedly compared with those in the same group before experiment and control group (P < 0.05, P < 0.01). The increase of antioxidase activities was earlier than the decease of ChE activity. It suggests that profenofos can result in the increases of the activities of SOD, CAT and GSH-Px, which may be earlier diagnostic index in profenofos poisoning.

Animals↗

PubMed2003

[Primary research of the effect of intestinal ischemia/reperfusion injury on Leptin concentrations].

OBJECTIVE: To explore the effect of intestinal ischemia/reperfusion injury on Leptin concentrations in serum and adipose tissue, and to find out the role of Leptin in acute inflammatory responses. METHODS: An intestinal ischemia-reperfusion injury model of rats was established, and used a highly-sensitive murine Leptin radioimmunoassay to check the change of Leptin concentrations in serum and adipose tissue. RESULTS: Serum Leptin level (10.82+/-0.83) microg/L significantly decreased after an injury of 60-minute ischemia and 30-minute reperfusion versus pre-experimental serum levels (16.46+/-3.21) microg/L; Leptin level in serum was higher than that in adipose tissue (4.466+/-2.63) mg/100g, and they both showed a similar changeable trend to increase step by step as reperfusion time extended (P=0.047). CONCLUSION: Leptin may be an inflammatory cytokine and may play a role in inflammatory responses such as intestinal ischemia/reperfusion.

Animals↗

PubMed2003

[Surgical management of hypopharyngeal cancer].

OBJECTIVE: To investigate the preservation of laryngeal function for the patients with hypopharyngeal cancer. METHODS: Two hundred and ninety-three cases of hypopharyngeal cancer with surgical management were reviewed retrospectively, and 222 cases were originated from pyriform sinus, 13 from post-cricoid, and 21 from posterior pharyngeal wall. Radiotherapy (37 cases), operation only (56 cases) and the combined treatment (operation plus radiation or chemotherapy, 200 cases) were adopted. 159 cases were treated with function preserved laryngectomy and 97 with total laryngectomy. RESULTS: The 5 year survival rates of patient with laryngeal function preserved and no laryngeal function preserved were 51.3%, 47.6% (for stage III); 40.4%, 43.3% (for stage IV), respectively. There were no significant differences in 5-year survival between the functionally preserved group and no functioned group (P > 0.05). The analysis of survival rates revealed a significant difference between combined therapy and radiotherapy. CONCLUSION: There is no significant difference between the survive rates of function preserved and non-preserved groups. Conservation laryngectomy improves the quality of patient's life, and combined therapy is the best choice for hypopharyngeal cancer.

Adult↗

PubMed2002

Porous polymer/bioactive glass composites for soft-to-hard tissue interfaces.

Porous composites consisting of a polysulfone (or cellulose acetate) matrix and bioactive glass particles were prepared by phase separation techniques. Microstructures were designed for potential application as an interconnect between artificial cartilage and bone. The effects of polymer type, concentration and molecular weight, as well as bioactive glass size and content, on the microstructures of the composites were studied. The composites have asymmetric structures with dense top layers and porous structures beneath. The microstructural features depend most strongly on the type of polymer, the interaction between the polymer and bioactive glass, and the glass content. The dense top layer could be removed by abrasion to make a structure with large pores (20-150 microm) exposed. Composites were immersed in simulated body fluid at body temperature. The growth of hydroxycarbonate apatite inside and on the composites demonstrates their potential for integration with bone. Composite modulus and break strength increased with increasing glass content due to the change in composition and pore content.

Adsorption↗

PubMed2002

Leishmania LPG3 encodes a GRP94 homolog required for phosphoglycan synthesis implicated in parasite virulence but not viability.

Leishmania promastigotes express an abundant cell surface glycoconjugate, lipophosphoglycan (LPG). LPG contains a polymer of the disaccharide-phosphate repeat unit Galbeta1,4Manalpha1-PO4, shared by other developmentally regulated molecules implicated in parasite virulence. Functional complementation of a Leishmania donovani LPG-defective mutant (OB1) accumulating a truncated LPG containing only the Manalpha1-PO4 residue of the first repeat unit identified LPG3, the Leishmania homolog of the mammalian endoplasmic reticulum (ER) chaperone GRP94. LPG3 resembles GRP94, as it localizes to the parasite ER, and lpg3(-) mutants show defects including down-regulation of surface GPI-anchored proteins and mild effects on other glycoconjugates. LPG3 binds cellular proteins and its Leishmania infantum GRP94 ortholog is highly immunogenic, suggesting a potential role in directing the immune response. However, null lpg3(-) mutants grow normally, are completely defective in the synthesis of phosphoglycans, and the LPG3 mRNA is regulated developmentally but not by stress or heat. Thus the role of LPG3/GRP94 in Leishmania metabolism differs significantly from other eukaryotes. Like the other glycoconjugate synthetic pathways in this parasite, its activity is focused on molecules implicated in virulence rather than viability.

Alleles↗

PubMed2002

Modulated insulin permeation across a glucose-sensitive polymeric composite membrane.

A glucose-sensitive polymeric composite membrane was prepared based on our previously developed stimuli-responsive membrane system. Membranes were cast from a mixture of glucose oxidase (GOD), catalase, and poly(N-isopropylacrylamide-co-methacrylic acid) (poly(NIPAm/MAA)) nanoparticles dispersed in a solution of a hydrophobic polymer. High efficiency of enzyme immobilization was achieved with undetectable leakage. The bioactivity of the immobilized GOD, as measured by pH change of glucose solutions, was found to be equivalent to approximately 80% of that of the free GOD. The addition of catalase markedly increased the oxidation rate of glucose. However, an optimal unit ratio of GOD to catalase and optimal enzyme loading were observed. The rate of insulin permeation through the membrane was modulated by glucose concentration due to shrinking or swelling of the embedded pH-sensitive nanoparticles. The response of insulin permeability to the change in the glucose concentration could be detected within 5-15 min. The permeability of insulin increased more than 3-fold as the glucose concentration was raised from 50 to 200 mg/dl. The average insulin permeability at 400 mg/dl of glucose was 8-fold that at 50 mg/dl in a continuous test in saline and was 6-fold in a three-cycle discontinuous test in pH 7.4 buffer.

Catalase↗

PubMed2002

Divergent regulation of dihydrofolate reductase between malaria parasite and human host.

For half a century, successful antifolate therapy against Plasmodium falciparum malaria has been attributed to host-parasite differences in drug binding to dihydrofolate reductase-thymidylate synthase (DHFR-TS). Selectivity may also arise through previously unappreciated differences in regulation of this drug target. The DHFR-TS of Plasmodium binds its cognate messenger RNA (mRNA) and inhibits its own translation. However, unlike translational regulation of DHFR or TS in humans, DHFR-TS mRNA binding is not coupled to enzyme active sites. Thus, antifolate treatment does not relieve translational inhibition and parasites cannot replenish dead enzyme.

Animals↗

PubMed2002

Optimized aeration by carbon dioxide gas for microalgal production and mass transfer characterization in a vertical flat-plate photobioreactor.

To optimize the aeration conditions for microalgal biomass production in a vertical flat-plate photobioreactor (VFPP), the effect of the aeration rate on biomass productivity was investigated under given conditions. Air enriched with 5% or 10% (v/v) CO(2) was supplied for the investigation at rates of 0.025-1 vvm. The CO(2) utilization efficiency, change of pH in the medium, and the optimum aeration rate were determined by evaluating biomass productivity. To investigate the VFPP mass transfer characteristics, the overall volumetric mass transfer coefficient, k(L)a, was evaluated for several different flat-plate sizes. Increasing the height of the VFPP could improve both the mass transfer of CO(2) and the illumination conditions, so this appeared to be a good method for scaling up. Based on a comparison of the k(L)a value at the optimum aeration rate with previously reported results, it was confirmed that the range of CO(2) concentration used in the experiments was cost-effective for mass culture.

Journal Article↗

PubMed2002

The effects of increased market competition on hospital services in Shandong and Henan Provinces.

The Chinese government began a major reform of the hospital sector in the early 1980s. The main aim was to increase productivity by phasing out prospective global budgets from the government, and encouraging between-hospital competition for the business of user-pay and insured patients. This goal was to be achieved without unreasonable prejudice to the financial sustainability of hospitals or to the fairness of access and service provision. We explored the effects of these changes by analysing data for four levels of hospital in two of the most populous provinces between 1985 and 1999. We used data envelope analysis, and found that the majority of hospitals experienced a decline in productivity. Social efficiency (measured by the level of provision of unnecessary services) also declined, especially in the largest hospitals that could easily increase the use of expensive technologies. Most hospitals increased their economic sustainability, measured as the ratio between revenue and expenditures. However, the lowest-level hospitals experienced stable or reduced sustainability due to their inability to compete with marketing by higher-level hospitals. We conclude that, although there were many benefits, the overall impact of the introduction of market forces may have been negative. An important factor was that not all aspects (such as supplier-induced demand) were adequately controlled by government agencies. We suggest ways of alleviating the most problematic elements of current arrangements.

Budgets↗

PubMed2002

Effects of single and repeated restraint stresses on the expression of beta(1)-adrenoceptor mRNA in the rat hypothalamus and midbrain.

We examined the effects of single and repeated restraint stresses on the expression of beta(1)-adrenoceptor mRNA in the rat midbrain and hypothalamus using reverse transcriptase-polymerase chain reaction (RT-PCR). After the rats had been restrained for 4 h (single stress), or for 4 h per day during 2 or 3 consecutive days, the hypothalamus and midbrain were removed immediately and beta(1)-adrenoceptor mRNA levels in these regions were determined by RT-PCR. Single stress significantly decreased the mRNA level in the hypothalamus, but the mRNA level was near control levels after 2 and 3 days of stress. In the midbrain, single stress had no effect on the mRNA level, but 2 days of stress significantly increased it.

Animals↗

PubMed2002

[Influence of peritoneal dialysate on nitric oxide production and viability of macrophage]

OBJECTIVE: To investigate the influence of commercial peritoneal dialysate (CDS) on function of macrophage. METHODS: Cultured peritoneal macrophages were divided into two experimental groups and their controls.(1) Macrophages were cultured in conditioned culture medium containing 50%CDS (0.139 mol/L glucose) for 24 h. (2)Macrophage were exposed to CDS containing 0.139mol/L glucose for 10, 30 and 60 min respectively, and then cultured in CDS-free medium for 24 h. The nitric oxide (NO) production and MTT in two groups were measured. In each control group, CDS was replaced by same amount of culture medium. RESULTS: NO production and MTT reduction ability (related to cell viability) of experimental groups were remarkably lower than those of controls and the NO production and MTT reduction in 60min CDS-exposed group were lower than that of 10 min and 30 min CDS-exposed group. CONCLUSION: Dialysate may have detrimental effects on viability and other function of macrophage and these effects may related to time length of CDS exposure.

Journal Article↗

PubMed2002

[Histological observation of the interface of oral epithelium and titanium implant with titanium dioxide on the surface]

OBJECTIVE: To investigate the healing process at the interface between oral epithelium and a titanium implant with titanium dioxide on the surface and whether a good epithelial barrier could be formed. METHODS: Titanium implants with titanium dioxide on the surface were placed in the mandibular alveolar area of Beagle dogs after their premolars had been removed three months previous. On the 15th day, second month and loading second month after implantation specimens were taken and examined after HE staining as well as by transmission electron microscopy. RESULTS: Fifteen days after implantation the epithelial collar was formed, junctional epithelium actively regenerated and attachment to the matrix on the surface of the implant occurred by hemidesmosomes. Two months after implantation junctional epithelium was increasing, showing three to four layers consistent with each other. Junctional epithelium appeared to be generated when stimulated by inflammation and shaped into epithelium rete pegs after loading for two months. CONCLUSION: Oral junctional epithelium can attach very well to titanium implants with titanium dioxide on the surface which also provides a biological barrier.

Journal Article↗