Biomedical subjects

C Zhang

Publications and source records attributed to C Zhang.

At least 55 records · Page 3Linked to original sources

PubMed2005

Toxicity, bioavailability and pharmacokinetics of a newly formulated colistin sulfate solution.

We formulated a new colistin sulfate injectable solution and tested its effectiveness, toxicity and pharmacokinetics in vivo on mice, rabbits, and piglets. When intramuscularly injected (i.m.) into rabbits at 0.5 mL per site, the 2.5% colistin sulfate solution caused no reaction at the injection site, but the 5.0% solution caused the muscle circumference to appear erythematic. Tested LD50 in CD-1 mice were 38.72 mg/kg for i.m. and 431.95 mg/kg for oral administration, respectively. At 15.0 mg/kg/day (i.m.) for 5 days, colistin sulfate caused obvious neurotoxicity to piglets with moderate granular degenerations in the epithelial tissues from kidney and liver. These toxic responses were not seen when colistin sulfate was injected at 10.0 mg/kg/day for 5 days. Pharmacokinetic studies revealed Cmax of 3.73 +/- 0.28 and 6.40 +/- 0.18 microg/mL, Tmax of 32 +/- 1.5 and 34 +/- 1.8 min, t(1/2beta) of 256 +/- 14 and 264 +/- 29 min, and absolute bioavailability of 95.94 and 88.45% for colistin sulfate intramuscularly injected to piglets at 2.5 and 5.0 mg/kg, respectively. Serum colistin sulfate concentration followed a two-compartment open model showing first-order absorption. The high bioavailability and the long-lasting serum retention time indicated that the new solution is suitable for i.m. in piglets with a recommended dose of 2.5 mg/kg injected twice daily.

Administration, Oral↗

PubMed2005

FMR1 alleles in Tasmania: a screening study of the special educational needs population.

The distribution of fragile X mental retardation-1 (FMR1) allele categories, classified by the number of CGG repeats, in the population of Tasmania was investigated in 1253 males with special educational needs (SEN). The frequencies of these FMR1 categories were compared with those seen in controls as represented by 578 consecutive male births. The initial screening was based on polymerase chain reaction analysis of dried blood spots. Inconclusive results were verified by Southern analysis of a venous blood sample. The frequencies of common FMR1 alleles in both samples, and of grey zone alleles in the controls, were similar to those in other Caucasian populations. Consistent with earlier reports, we found some (although insignificant) increase of grey zone alleles in SEN subjects compared with controls. The frequencies of predisposing flanking haplotypes among grey zone males FMR1 alleles were similar to those seen in other Caucasian SEN samples. Contrary to expectation, given the normal frequency of grey zone alleles, no premutation (PM) or full mutation (FM) allele was detected in either sample, with only 15 fragile X families diagnosed through routine clinical admissions registered in Tasmania up to 2002. An explanation of this discrepancy could be that the C19th founders of Tasmania carried few PM or FM alleles. The eight to ten generations since white settlement of Tasmania has been insufficient time for susceptible grey zone alleles to evolve into the larger expansions.

Adolescent↗

PubMed2005

Genetic diversity among varieties and wild species accessions of pea (Pisum sativum L.) based on molecular markers, and morphological and physiological characters.

Random amplified polymorphic DNA, simple sequence repeat, and inter-simple sequence repeat markers were used to estimate the genetic relations among 65 pea varieties (Pisum sativum L.) and 21 accessions from wild Pisum subspecies (subsp.) abyssinicum, asiaticum, elatius, transcaucasicum, and var. arvense. Fifty-one of these varieties are currently available for growers in western Canada. Nei and Li's genetic similarity (GS) estimates calculated using the marker data showed that pair-wise comparison values among the 65 varieties ranged from 0.34 to 1.00. GS analysis on varieties grouped according to their originating breeding programs demonstrated that different levels of diversity were maintained at different breeding programs. Unweighted pair-group method arithmetic average cluster analysis and principal coordinate analysis on the marker-based GS grouped the cultivated varieties separately from the wild accessions. The majority of the food and feed varieties were grouped separately from the silage and specialty varieties, regardless of the originating breeding programs. The analysis also revealed some genetically distinct varieties such as Croma, CDC Handel, 1096M-8, and CDC Acer. The relations among the cultivated varieties, as revealed by molecular-marker-based GS, were not significantly correlated with those based on the agronomic characters, suggesting that the 2 systems give different estimates of genetic relations among the varieties. However, on a smaller scale, a consistent subcluster of genotypes was identified on the basis of agronomic characters and their marker-based GS. Furthermore, a number of variety-specific markers were identified in the current study, which could be useful for variety identification. Breeding strategies to maintain or enhance the genetic diversity of future varieties are proposed.

Genetic Markers↗

PubMed2005

NF-kappaB activation in human dental pulp stem cells by TNF and LPS.

Post-natal human dental pulp stem cells (DPSCs) represent a unique precursor population in the dental pulp, which has multipotential and can regenerate a dentin/pulp-like structure. Because the dental pulp is frequently infected by oral bacteria due to dental decay, in this study, we examined whether lipopolysaccharide (LPS) and tumor necrosis factor (TNF) activated the immunologic transcription factor nuclear factor kappa B (NF-kappaB) in DPSCs. We found that both TNF and LPS activated the I-kappa B kinase complex (IKK) in DPSCs to induce the phosphorylation and degradation of IkappaBalpha, resulting in the nuclear translocation of NF-kappaB. Consistently, both TNF and LPS rapidly induced the expression of the NF-kappaB-dependent gene interleukin-8 (IL-8). However, unlike in monocytes, we found that LPS could not induce the phosphorylation of the NF-kappaB active subunit p65 in DPSCs. In summary, our studies suggest that DPSCs may be involved in immune responses during pulpal infection through activating NF-kappaB.

Blotting, Northern↗

PubMed2005

The pathogenesis of discogenic low back pain.

Discogenic low back pain is a common cause of disability, but its pathogenesis is poorly understood. We collected 19 specimens of lumbar intervertebral discs from 17 patients with discogenic low back pain during posterior lumbar interbody fusion, 12 from physiologically ageing discs and ten from normal control discs. We investigated the histological features and assessed the immunoreactive activity of neurofilament (NF200) and neuropeptides such as substance P (SP) and vasoactive-intestinal peptide (VIP) in the nerve fibres. The distinct histological characteristic of the painful disc was the formation of a zone of vascularised granulation tissue from the nucleus pulposus to the outer part of the annulus fibrosus along the edges of the fissures. SP-, NF- and VIP-immunoreactive nerve fibres in the painful discs were more extensive than in the control discs. Growth of nerves deep into the annulus fibrosus and nucleus pulposus was observed mainly along the zone of granulation tissue in the painful discs. This suggests that the zone of granulation tissue with extensive innervation along the tears in the posterior part of the painful disc may be responsible for causing the pain of discography and of discogenic low back pain.

Adult↗

PubMed2004

Sole BCR-ABL inhibition is insufficient to eliminate all myeloproliferative disorder cell populations.

Protein kinase inhibitors can be effective in treating selected cancers, but most suppress several kinases. Imatinib mesylate has been useful in the treatment of Philadelphia chromosome-positive chronic myelogenous leukemia and B cell acute lymphoblastic leukemia through the inhibition of BCR-ABL tyrosine kinase activity. Imatinib mesylate has also been shown to inhibit KIT, ARG, and platelet-derived growth factor receptors alpha and beta, and potentially other tyrosine kinases. We have produced a mutant allele of BCR-ABL (T315A) that is uniquely inhibitable by the small molecule 4-amino-1-tert-butyl-3-(1-naphthyl)pyrazolo[3,4-d]pyrimidine and used it to demonstrate that sole suppression of BCR-ABL activity was insufficient to eliminate BCR-ABL(+) KIT(+)-expressing immature murine myeloid leukemic cells. In contrast, imatinib mesylate effectively eliminated BCR-ABL(+) KIT(+)-expressing leukemic cells. In the cellular context of mature myeloid cells and Pro/Pre B cells that do not express KIT, monospecific BCR-ABL inhibition was quantitatively as effective as imatinib mesylate in suppressing cell growth and inducing apoptosis. These results suggest that the therapeutic effectiveness of small molecule drugs such as imatinib mesylate could be due to the inhibitor's ability to suppress protein kinases in addition to the dominant target.

Apoptosis↗

PubMed2004

Genome diversity among regional populations of Francisella tularensis subspecies tularensis and Francisella tularensis subspecies holarctica isolated from the US.

Francisella tularensis is a highly infectious facultative intracellular pathogen that is considered a potential agent of bioterrorism. Four different F. tularensis subspecies have been identified and they appear to display different ecological and virulence characteristics as well as differences in geographical distribution. One simple explanation for the variation in ecological and virulence characteristics is that they are conferred by differences in genome content. To characterize genome content among stains isolated from United States, we have used a DNA microarray designed from a shotgun library of a reference strain. Polymorphisms distributed among polyphyletic sets of strains was the most common pattern of genome alteration observed, indicating that strain-specific genome variability is significant. Nonetheless, 13 different contiguous segments of the genome were found to be missing exclusively in each of the subsp. holarctica strains tested. All 13 are associated with repeat sequences or transposases that could promote insertion/deletion events. Comparison of the live vaccine strain to other holarctica strains also identified three regions that are absent exclusively in the live vaccine strain derived from holarctica.

Bacterial Vaccines↗

PubMed2004

Hierarchical structure in healthy and diseased human heart rate variability.

It is shown that the healthy and diseased human heart rate variability (HRV) possesses a hierarchical structure of the She-Leveque (SL) form. This structure, first found in measurements in turbulent fluid flows, implies further details in the HRV multifractal scaling. The potential of diagnosis is also discussed based on the characteristics derived from the SL hierarchy.

Biophysical Phenomena↗

PubMed2004

Coherent electron transport through an azobenzene molecule: a light-driven molecular switch.

We apply a first-principles computational approach to study a light-sensitive molecular switch. The molecule that comprises the switch can convert between a trans and a cis configuration upon photoexcitation. We find that the conductance of the two isomers varies dramatically, which suggests that this system has potential application as a molecular device. A detailed analysis of the band structure of the metal leads and the local density of states of the system reveals the mechanism of the switch.

Journal Article↗

PubMed2004

Downregulation of N1 gene expression inhibits the initial heartbeating and heart development in axolotls.

Recessive mutant gene c in the axolotl results in a failure of affected embryos to develop contracting hearts. This abnormality can be corrected by treating the mutant heart with RNA isolated from normal anterior endoderm or from endoderm conditioned medium. A cDNA library was constructed from the total conditioned medium RNA using a random priming technique in a pcDNAII vector. We have previously identified a clone (designated as N1) from the constructed axolotl cDNA library, which has a unique nucleotide sequence. We have also discovered that the N1 gene product is related to heart development in the Mexican axolotl [Cell Mol. Biol. Res. 41 (1995) 117]. In the present studies, we further investigate the role of N1 on heartbeating and heart development in axolotls. N1 mRNA expression has been determined by using semi-quantitative RT-PCR with specifically designed primers. Normal embryonic hearts (at stages 30-31) have been transfected with anti-sense oligonucleotides against N1 to determine if downregulation of N1 gene expression has any effect on normal heart development. Our results show that cardiac N1 mRNA expression is partially blocked in the hearts transfected with anti-sense nucleotides and the downregulation of N1 gene expression results in a decrease of heartbeating in normal embryos, although the hearts remain alive as indicated by calcium spike movement throughout the hearts. Confocal microscopy data indicate some myofibril disorganization in the hearts transfected with the anti-sense N1 oligonucleotides. Interestingly, we also find that N1 gene expression is significantly decreased in the mutant axolotl hearts. Our results suggest that N1 is a novel gene in Mexican axolotls and it probably plays an important role in myofibrillogenesis and in the initiation of heartbeating during heart development.

Ambystoma mexicanum↗

PubMed2004

Adenovirus-based vascular endothelial growth factor gene delivery to human pancreatic islets.

Islet transplantation is limited by islet graft failure due to poor revascularization, host immune rejection and nonspecific inflammatory response. Delivery of human vascular endothelial growth factor (hVEGF) gene to the islets is likely to promote islet revascularization and survival. We used a bicistronic adenoviral vector encoding hVEGF and CpG-free allele of green fluorescent protein (Adv-GFP-hVEGF) and introduced into human pancreatic islets by transfection. We found that transfection efficiency and apoptosis were dependent on the multiplicity of infection (MOI). Compared to Adv-GFP transfected and nontransfected islets, the levels of hVEGF secreted from Adv-GFP-hVEGF transfected islets were higher and exhibit a linear relationship between hVEGF expression and MOI (10-5000). Persistent, but low level expression of hVEGF from nontransfected islets was also observed. This may be due to expression of the endogenous hVEGF gene under hypoxic conditions. The levels of DNA fragmentation determined by ELISA of islet lysates were dependent on the MOI of Adv-GFP-hVEGF. On glucose challenge, insulin release from transfected islets was comparable to nontransfected islets. Immunohistochemical staining for hVEGF was very high in Adv-GFP-hVEGF transfected islets. Weak staining was also observed for hCD31 in both transfected and nontransfected islets. These findings suggest that Adv-GFP-hVEGF is a potential candidate for promoting islet revascularization.

Adenoviridae↗

PubMed2004

Ablation of canine prostate using two-stage intraprostatic hot agarose solution and enzyme injection.

UNLABELLED: Enzyme ablation of the hyperplastic prostate may be an ideal method of management of BPH. However, the unsatisfactory ablation affects in vivo contrast with successful in vitro results limiting the enthusiasm for further research. In this study, we make efforts to solve the problems in the use of enzyme ablation of BPH in vivo and to measure satisfactory effect. MATERIAL AND METHODS: A total of 18 hybrid dogs between the ages of 7 and 11 y underwent this experiment. Eight dogs were divided into four groups according to the injection formula: enzyme solution, hot D-Hanks' plus enzyme solution, hot agarose plus enzyme solution, and hot agarose solution alone. After selecting the agarose plus enzyme solution group in the first month, the remainder 10 dogs were treated with this two-stage method. Intravenous or oral antibiotics were administered perioperatively. All operations were performed directly by way of laparotomy. The prostates were observed and harvested with surrounding tissue at 24 hrs, 7 days, 14 days, 1 month and 3-5 months after treatment. Gross and microscopic examinations were performed. RESULTS: Only agarose plus enzyme group shows obvious cavity formation with concomitant size reduction and softening of the prostate ablation effect in the four groups. At 24 h after injection, the prostates demonstrated cavity formation containing liquefied necrotic tissue. The liquefied tissue was absorbed in 7-14 days. At 1 month, the size of most prostates decreased with a corresponding decrease in the size of the cavities. The cavities nearly disappeared within 3-5 months, and the size of prostates decreased to between 1/2 and 1/4 of the pretreatment sizes. All prostates had intact urethral mucosa and capsule. No complications directly related to enzyme ablation were identified. In the control groups there were no significant cavities or decrease in prostate size. CONCLUSIONS: This two-stage thermal and enzyme ablative method can significantly ablate prostate tissue without identifiable complications, and would be possibly applied to treating human BPH in the future.

Administration, Oral↗

PubMed2004

Heritability of C-reactive protein and association with apolipoprotein E genotypes in Japanese Americans.

Numerous studies have demonstrated that increased C-reactive protein (CRP) levels predict coronary heart disease, stroke, peripheral vascular disease, and diabetes, and are associated with features of the metabolic syndrome. Only three previous studies have investigated the heritability of CRP levels, primarily in samples of Caucasian families. The purpose of the present study was to estimate the magnitude of genetic influences on CRP levels, and to examine potential associations between variation in the APOE gene and CRP levels, using a sample of 562 individual Japanese Americans from 68 extended kindreds. In general, correlation coefficients between first-degree relatives for CRP were approximately 0.2, and spouse correlations did not differ from zero, consistent with genetic influences. Heritability estimates were approximately 0.3 (p < 0.01), even with adjustment for factors known to influence CRP levels. A significant relationship was seen between unadjusted CRP levels and APOE genotypes (p = 0.02), with the highest mean CRP level among epsilon2 carriers (1.20 mg/L), and nearly the same mean levels among epsilon3/epsilon3 subjects and epsilon4 carriers (0.72 and 0.74 mg/L, respectively). However, this relationship was diminished with adjustment for covariates (p = 0.07). These results demonstrate the presence of both genetic and environmental effects on CRP levels among Asian Americans, and additional studies are needed to determine if the APOE gene contributes to these genetic influences.

Adult↗

PubMed2004

Methylenetetrahydrofolate reductase 677 C-->T polymorphism and plasma folate in relation to pre-eclampsia risk among Peruvian women.

OBJECTIVES: Pre-eclampsia is an important cause of maternal and fetal morbidity and mortality worldwide. Hyperhomocyst(e)inemia in pregnancy is associated with an increased risk of pre-eclampsia in most studies. Nutritional and genetic factors regulate homocyst(e)ine levels. A missense mutation 677 C-->T in the gene for methylenetetrahydrofolate reductase (MTHFR) has been associated with an increased pre-eclampsia risk in some, although not most, previously studied populations. METHODS: To further understand the role of this polymorphism in the etiology of pre-eclampsia, we genotyped a total of 125 pre-eclamptics and 179 normotensive pregnant Peruvian women. RESULTS: The wild-type allele frequency among cases and controls was 54% and 58%, respectively. Twenty percent of cases and 17% of controls were homozygous for the 677 C-->T MTHFR genotype (T/T). After adjustment for confounding by covariates including maternal age, nulliparity, pre-pregnancy body mass index and use of prenatal vitamins, women homozygous for the 677 C-->T MTHFR genotype (T/T) experienced a modest, statistically non-significant increased risk of pre-eclampsia (adjusted OR 1.6, 95% CI 0.7, 3.8). Maternal folate deficiency was associated with a statistically non-significant doubling in risk of pre-eclampsia in this population (adjusted OR 2.0, 95% CI 0.9, 4.3). CONCLUSIONS: There was no evidence to suggest that pre-eclampsia risk is positively associated with the T/T genotype overall, or in the context of folate deficiency.

Adult↗

PubMed2004

Randomized phase II trial of gemcitabine plus irinotecan or docetaxel in stage IIIB or stage IV NSCLC.

BACKGROUND: To evaluate the activity and tolerability of gemcitabine plus irinotecan or docetaxel as first-line chemotherapy for advanced non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: Eligible patients with chemotherapy-naïve stage IIIB or IV NSCLC were randomized to receive gemcitabine 1000 mg/m2 on days 1 and 8, plus either irinotecan 100 mg/m2 or docetaxel 40 mg/m2 on days 1 and 8. Treatment was administered every 3 weeks. RESULTS: Of the 80 enrolled patients with stage IIIB or IV NSCLC, 78 were evaluable for activity and safety. Overall response rates, consisting of partial responses, were 12.8% [95% confidence interval (CI) 4% to 35%] for gemcitabine-irinotecan and 23.1% (95% CI 10% to 42%) for gemcitabine-docetaxel. Median overall survival was 7.95 months (95% CI 5.2-10.2) and 12.8 months (95% CI 7.9-17.1) for gemcitabine-irinotecan and gemcitabine-docetaxel, respectively. The corresponding estimated 1-year survivals were 23% and 51%, respectively. The 2-year survival rate in arm A (gemcitabine-irinotecan) is not currently estimable. The 2-year survival rate for arm B (gemcitabine-docetaxel) is 22% (95% CI 6% to 37%). Both combinations were well tolerated; the most common hematological toxicity was neutropenia, which occurred in 26% of patients in each treatment arm. CONCLUSIONS: These results suggest that gemcitabine plus docetaxel or irinotecan is well tolerated in patients with chemotherapy-naïve advanced NSCLC. The survival data with the combination gemcitabine-docetaxel are promising. Gemcitabine-docetaxel combination therapy may be particularly useful for patients who have experienced toxicities with a platinum regimen or in patients who may be more susceptible to platinum-related toxicity.

Adult↗

PubMed2004

Combined modality trials of the Cancer and Leukemia Group B in stage III non-small-cell lung cancer: analysis of factors influencing survival and toxicity.

BACKGROUND: Combined modality therapy (CMT) is the standard of care for patients with unresectable stage III non-small-cell lung cancer (NSCLC); however, insufficient data are available regarding prognostic factors in this disease setting. PATIENTS AND METHODS: Six hundred and ninety-four patients included in five trials conducted by the Cancer and Leukemia Group B evaluating CMT in stage III NSCLC were included in this analysis. The primary objective was to identify factors that were predictors of survival and selected radiation-related toxicities using Cox regression models and logistic regression analysis. RESULTS: The Cox model shows that performance status (PS) 1 [hazard ratio (HR) 1.24; 95% confidence interval (CI) 1.06-1.45; P=0.009] and thoracic radiation therapy (TRT) only (HR 1.58; 95% CI 1.22-2.05; P=0.001) predicted for poorer survival, while baseline hemoglobin >/=12 g/dl predicted for improved survival (HR 0.67; 95% CI 0.55-0.81; P </=0.0001). Multivariate logistic regression showed an increase of grade 3 + esophagitis among patients with PS 0 [odds ratio (OR) 1.7; 95% CI 1.1-2.7; P=0.029), >5% weight loss (OR 2.9; 95% CI 1.3-6.6; P=0.008) and patients receiving concurrent chemoradiation (OR 7.3; 95% CI 3.4-15.6; P=0.0001). CONCLUSIONS: Baseline hemoglobin and PS, as well as the use of CMT, have the greatest effect on survival in unresectable stage III NSCLC. The use of concurrent chemoradiation increases the risk of esophagitis, which remains the primary radiation-related toxicity.

Adult↗

PubMed2004

Low intensity pulsed ultrasound stimulates osteogenic activity of human periosteal cells.

The effect of low intensity pulsed ultrasound on human periosteal cells was investigated. Normal human periosteum was obtained to culture the periosteal cells. After characterization, cultures of periosteal cells at Days 2 and 4 were treated with ultrasound for 5, 10, and 20 minutes respectively. Assessments were done to assess total number of viable cells, cell proliferation, alkaline phosphatase activity, osteocalcin secretion, vascular endothelial growth factor expression, and calcium nodule formation. With the cells not treated with ultrasound as the control, the results showed that ultrasound did not affect the total number of viable cells. It stimulated cell proliferation at the early phase of cell culture. The activity of alkaline phosphatase was increased significantly in the culture at Day 4. A similar effect was seen with osteocalcin secretion and the responses were dose-dependent. The vascular endothelial growth factor secretion increased in Day 2 and Day 4 cultures with the dose-dependent effect. Formation of calcium nodules was significantly higher with ultrasound treatment. We think that low intensity pulsed ultrasound stimulated periosteal cell proliferation and differentiation toward osteogenic lineage. The dose-dependent effect on osteogenic activities may modify the existing treatment regimen. Ultrasound treatment should be started from the beginning of fracture healing.

Adult↗

PubMed2004

Identification of Escherichia coli O172 O-antigen gene cluster and development of a serogroup-specific PCR assay.

AIM: To characterize the locus for O-antigen biosynthesis from Escherichia coli O172 type strain and to develop a rapid, specific and sensitive PCR-based method for identification and detection of E. coli O172. METHODS AND RESULTS: DNA of O-antigen gene cluster of E. coli O172 was amplified by long-range PCR method using primers based on housekeeping genes galF and gnd Shot gun bank was constructed and high quality sequencing was performed. The putative genes for synthesis of UDP-FucNAc, O-unit flippase, O-antigen polymerase and glycosyltransferases were assigned by the homology search. The evolutionary relationship between O-antigen gene clusters of E. coli O172 and E. coli O26 is shown by sequence comparison. Genes specific to E. coli O172 strains were identified by PCR assays using primers based on genes for O-unit flippase, O-antigen polymerase and glycosyltransferases. The specificity of PCR assays was tested using all E. coli and Shigella O-antigen type strains, as well as 24 clinical E. coli isolates. The sensitivity of PCR assays was determined, and the detection limits were 1 pg microl(-1) chromosomal DNA, 0.2 CFU g(-1) pork and 0.2 CFU ml(-1) water. The total time required from beginning to end of the procedure was within 16 h. CONCLUSION: The O-antigen gene cluster of E. coli O172 was identified and PCR assays based on O-antigen specific genes showed high specificity and sensitivity. SIGNIFICANCE AND IMPACT OF THE STUDY: An O-antigen gene cluster was identified by sequencing. The specific genes were determined for E. coli O172. The sensitivity of O-antigen specific PCR assay was tested. Although Shiga toxin-producing O172 strains were not yet isolated from clinical specimens, they may emerge as pathogens.

Base Sequence↗