Biomedical subjects

Z Li

Publications and source records attributed to Z Li.

At least 487 records · Page 27Linked to original sources

PubMed2000

Active cell migration in retransplanted rat cardiac allografts during the course of chronic rejection.

BACKGROUND: Chronic allograft vasculopathy (CAV) is caused by the infiltration of host immune cells to a graft, but it has been technically difficult to monitor the movements of the cells in graft rejection. METHODS: We used a male-specific gene, SRY, as a marker to investigate the dynamics of host cells in a model of CAV in which immunosuppression was unnecessary and anti-male responses were practically negligible. Fluorescent-based real-time quantitative polymerase chain reaction (PCR) was adapted to estimate the fraction of host cells in a graft by the ratio of SRY to IL-2 gene. Using this technique, we studied the turnover and migration of host cells during the course of CAV progression by retransplanting female allografts from male to female or from female to male rats. RESULTS: We detected histologic CAV 60 days after retransplantation in allografts retransplanted to the F(1) progeny of donor x recipient on the 5th day, but not in those retransplanted on the 3rd day, regardless of the mismatches in the genders. Most of the initial infiltrating cells disappeared rapidly in both cases. The fraction of migrating cells from the second recipient, however, continuously increased in allografts developing CAV, and 60 days after retransplantation exceeded 50%, whereas it stayed at 5% to 15% in those not developing CAV. ED-1-positive macrophages/monocytes were likely candidates for the migrated cells. CONCLUSION: We have developed a simple method to measure the migration of host cells into a graft. This technique was useful, at least in certain rat strains, to investigate the cellular mechanisms of chronic cardiac allograft rejection.

Animals↗

PubMed2000

Microtubule binding to Smads may regulate TGF beta activity.

Smad proteins are intracellular signaling effectors of the TGF beta superfamily. We show that endogenous Smad2, 3, and 4 bind microtubules (MTs) in several cell lines. Binding of Smads to MTs does not require TGF beta stimulation. TGF beta triggers dissociation from MTs, phosphorylation, and nuclear translocation of Smad2 and 3, with consequent activation of transcription in CCL64 cells. Destabilization of the MT network by nocodazole, colchicine, or a tubulin mutant disrupts the complex between Smads and MTs and increases TGF beta-induced Smad2 phosphorylation and transcriptional response in CCL64 cells. These data demonstrate that MTs may serve as a cytoplasmic sequestering network for Smads, controlling Smad2 association with and phosphorylation by activated TGF beta receptor I, and suggest a novel mechanism for the MT network to negatively regulate TGF beta function.

Activin Receptors, Type I↗

PubMed2000

Analysis of neurotoxin 3-N-oxalyl-L-2,3-diaminopropionic acid and its alpha-isomer in Lathyrus sativus by high-performance liquid chromatography with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatization.

A method was developed for the quantitative determination of the neurotoxic nonprotein amino acid, 3-N-oxalyl-L-2,3-diaminopropionic acid (beta-ODAP), and its nontoxic alpha-isomer, 2-N-oxalyl-L-2, 3-diaminopropionic acid (alpha-ODAP), in the plant samples of Lathyrus sativus after derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) by reversed-phase high-performance liquid chromatography (HPLC). Hippuric acid was used as an internal standard. A linear response was recorded in the concentration rang 0.32-32 nmol with r > 0.999. The RP HPLC detection limit for both isomers is 1.8 ng. According to different experimental needs, a ternary gradient system can be used to determine toxin and other nonprotein amino acids. The RP HPLC method and a colorimetric method were compared for measuring ODAP.

Amino Acids, Diamino↗

PubMed2000

Synthesis and fungicidal activity against Rhizoctonia solani of 2-alkyl (Alkylthio)-5-pyrazolyl-1,3,4-oxadiazoles (Thiadiazoles).

Some series of 2-alkyl (alkythio)-5-((4-chloro)-3-ethyl-1-methyl-1H-pyrazole-5-yl)-1,3, 4-oxadiazoles (thiadiazoles) were prepared as potential fungicides. Their fungicidal activity was evaluated against rice sheath blight, which is a major disease of rice in China. Structure-activity relationships for the screened compounds were evaluated and discussed. It was found that 5-(4-chloro-3-ethyl-1-methyl-1H-pyrazole-5-yl)-1,3, 4-thiadiazole-2-thione has the higher fungicidal activity.

Fungicides, Industrial↗

PubMed2000

Neuropathogenesis of chimeric simian human immunodeficiency virus infection in rhesus macaques.

Comparative studies were performed to determine the neuropathogenesis of infection in macaques with simian human immunodeficiency virus (SHIV)89.6P and SHIV(KU). Both viruses utilize the CD4 receptor and CXCR4 co-receptor. However, in addition, SHIV89.6P uses the CCR5 co-receptor. Both agents are dual tropic for CD4+ T cells and blood-derived macrophages of rhesus macaques. Following inoculation into macaques, both caused rapid elimination of CD4+ T cells but they varied greatly in mechanisms of neuropathogenesis. Two animals infected with SHIV89.6P developed typical lentiviral encephalitis in which multinucleated giant cell formation, nodular accumulations of microglial cells, activated macrophages and astrocytes, and perivascular accumulations of mononuclear cells were present in the brain. Many of the macrophages in these lesions contained viral RNA. Three macaques infected with SHIV(KU) and killed on days 6, 11 and 18, respectively, developed a slowly progressive infection in the CNS but macrophages were not productively infected and there were no pathological changes in the brain. Two other animals infected with this virus and killed several months later showed minimal infection in the brain even though one of the two developed encephalitis of unknown etiology. The basic difference in the mechanisms of neuropathogenesis by the two viruses may be related to co-receptor usage. SHIV89.6P, in utilizing the CCR5 co-receptor, caused neuropathogenic effects that are similar to other neurovirulent primate lentiviruses.

AIDS Dementia Complex↗

PubMed2000

Sociable and prosocial dimensions of social competence in Chinese children: common and unique contributions to social, academic, and psychological adjustment.

A sample of 6th-grade children (N = 470), initially aged 12 years, in Shanghai, People's Republic of China, participated in this longitudinal study. Data on children's sociability and prosocial orientation were collected from peer assessments. Information on indexes of adjustment was obtained from multiple sources. The results indicated that sociable and prosocial functions were 2 overlapping, but distinct, dimensions of social competence and had common as well as unique contributions to the prediction of adjustment in specific areas. Whereas prosocial orientation was mainly predictive of social and school adjustment and externalizing problems, sociability uniquely contributed to the prediction of internalizing problems and emotional adjustment. Finally, prosocial orientation and sociability might moderate the development of adjustment difficulties.

Achievement↗

PubMed2000

Rho GTPases regulate distinct aspects of dendritic arbor growth in Xenopus central neurons in vivo.

The development and structural plasticity of dendritic arbors are governed by several factors, including synaptic activity, neurotrophins and other growth-regulating molecules. The signal transduction pathways leading to dendritic structural changes are unknown, but likely include cytoskeleton regulatory components. To test whether GTPases regulate dendritic arbor development, we collected time-lapse images of single optic tectal neurons in albino Xenopus tadpoles expressing dominant negative or constitutively active forms of Rac, Cdc42 or RhoA. Analysis of images collected at two-hour intervals over eight hours indicated that enhanced Rac activity selectively increased branch additions and retractions, as did Cdc42 to a lesser extent. Activation of endogenous RhoA decreased branch extension without affecting branch additions and retractions, whereas dominant-negative RhoA increased branch extension. Finally, we provide data suggesting that RhoA mediates the promotion of normal dendritic arbor development by NMDA receptor activation.

2-Amino-5-phosphonovalerate↗

PubMed2000

Retroviral transduction of T lymphocytes for suicide gene therapy in allogeneic stem cell transplantation.

Transplantation of suicide gene modified allogeneic T lymphocytes is an approach to prevent T cell mediated GVHD while preserving the 'graft-versus-leukemia' (GVL) effect of an allograft. A prerequisite for such a therapy is the efficient transduction of T cells with suitable vectors. Since existing techniques allow only insufficient transduction of T cells, the development of more efficient gene transfer protocols into these cells is of great importance. We present here a protocol for the highly efficient transduction of human primary T cells at high densities (1 x 10(6) cells/ml) by retroviral infection. The presented protocol allowed us to obtain transduction rates of more than 70% of CD3+ cells after two cycles of infection. It is based on the use of FBS-free media for both the production of retrovirus-containing supernatant, as well as the cultivation of the primary T cells. Since the protocol presented here works just as efficiently under large scale conditions, it may easily be adapted to clinical needs and 'good manufacturing practice' (GMP) standards.

Fibronectins↗

PubMed2000

Placebo-controlled, randomized, evaluator-blinded endoscopy study of risedronate vs. aspirin in healthy postmenopausal women.

BACKGROUND: Bisphosphonates are effective treatments for osteoporosis. Since some primary amino bisphosphonates are associated with oesophageal injury, we conducted a study of the upper gastrointestinal effects of risedronate, a pyridinyl bisphosphonate. METHODS: Healthy, postmenopausal women received risedronate 5 mg (n=26), aspirin 2600 mg (n=27), or placebo (n=27) daily for 14 days and underwent endoscopy at baseline, Day 8 and Day 15. RESULTS: Oesophageal erosions were noted in one subject in the aspirin group, two in the placebo group, and none in the risedronate group, and an ulcer in one aspirin-treated subject. Gastric erosions and ulcers were observed most frequently in the aspirin group. Gastric ulcers were noted in eight subjects in the aspirin group, one in the placebo group, and none in the risedronate group (P=0.010, placebo vs. aspirin; P=0.002, risedronate vs. aspirin). Duodenal erosions and ulcers were observed in the aspirin group only. Gastroduodenal erosion scores of three or more occurred more frequently in the aspirin than in the risedronate and placebo groups (P < 0.001). CONCLUSIONS: Risedronate 5 mg was not associated with oesophageal or gastroduodenal ulcers in healthy, postmenopausal women, a population representative of patients who will receive risedronate in the clinical setting.

Adult↗

PubMed2000

Identification of a unique domain essential for Escherichia coli DNA topoisomerase III-catalysed decatenation of replication intermediates.

A 17-amino-acid residue domain has been identified in Escherichia coli DNA topoisomerase III (Topo III) that is essential for Topo III-mediated resolution of DNA replication intermediates in vitro. Deletion of this domain reduced Topo III-catalysed resolution of DNA replication intermediates and decatenation of multiply linked plasmid DNA dimers by four orders of magnitude, whereas reducing Topo III-catalysed relaxation of negatively supercoiled DNA substrates only 20-fold. The presence of this domain has been detected in multiple plasmid-encoded topoisomerases, raising the possibility that these enzymes may also be decatenases.

Amino Acid Sequence↗

PubMed2000

Molecular cloning and characterization of calreticulin, a calcium-binding protein involved in the regeneration of rice cultured suspension cells.

A full-length cDNA clone encoding a phosphoprotein (pp56) involved in the regeneration of rice (Oryza sativa L.)-cultured suspension cells was isolated by screening a rice cultured suspension cell cDNA library. The 1558-bp cDNA sequence contains an ORF encoding an acidic (pI 4.38) protein of 424 amino acids (47.9 kDa), sharing 70-93% and 50-53% homology with other plant and mammalian calreticulins, respectively. Sequence analysis of the cDNA clone revealed several significant conserved motifs, including a calreticulin family repeat motif in the central domain and two calreticulin family motifs in the N-domain, indicating that this gene is a rice calreticulin (CRO1). The CRO1 gene in long-term rice cultured suspension cells shows constitutive expression in both suspension culture and regeneration media. In contrast, expression of the CRO1 gene in short-term rice cultured suspension cells, which possess regeneration potential, is increased dramatically when these cells are transferred to the regeneration medium. After approximately 2 weeks in the regeneration medium, the expression of the CRO1 gene reverts to constitutive levels. These results demonstrate the presence of calreticulin in rice cultured suspension cells and its developmental regulation during the regeneration of rice cultured suspension cells.

Amino Acid Sequence↗

PubMed2000

Peptides with antimicrobial activity from four different families isolated from the skins of the North American frogs Rana luteiventris, Rana berlandieri and Rana pipiens.

The skins of frogs of the genus Rana synthesize a complex array of antimicrobial peptides that may be grouped into eight families on the basis of structural similarity. A total of 24 peptides with differential growth-inhibitory activity towards the Gram-positive bacterium Staphylococcus aureus, the Gram-negative bacterium Escherichia coli and the yeast Candida albicans were isolated from extracts of the skins of three closely related North American frogs, Rana luteiventris (spotted frog), Rana berlandieri (Rio Grande leopard frog) and Rana pipiens (Northern leopard frog). Structural characterization of the antimicrobial peptides demonstrated that they belonged to four of the known families: the brevinin-1 family, first identified in skin of the Asian frog Rana porosa brevipoda; the esculentin-2 family, first identified in the European frog Rana esculenta; the ranatuerin-2 family, first identified in the North American bullfrog Rana catesbeiana; and the temporin family, first identified in the European frog Rana temporaria. Peptides belonging to the brevinin-2, ranalexin, esculentin-1 and ranatuerin-1 families were not identified in the extracts. Despite the close phylogenetic relationship between the various species of Ranid frogs, the distribution and amino-acid sequences of the antimicrobial peptides produced by each species are highly variable and species-specific, suggesting that they may be valuable in taxonomic classification and molecular phylogenetic analysis.

Amino Acid Sequence↗

PubMed2000

2E4/Kaptin (KPTN)--a candidate gene for the hearing loss locus, DFNA4.

Stereocilia of the inner ear play an integral role in the mechanotransduction of sound. Their structural support is derived from actin filaments and actin-binding proteins. We have identified a novel actin-binding protein, 2E4-kaptin (KPTN), which appears to be involved in this structural network. Using double label immunofluorescence, we now show that KPTN extends beyond the barbed ends of actin filaments at the tips of stereocilia, and using cloned human cDNA, we mapped KPTN to chromosome 19q13.4. A combination of FISH, radiation hybrid mapping and YAC screening localized KPTN between markers D19S412 and NIB1805, making this gene an excellent functional and positional candidate for DFNA4, a form of autosomal dominant non-syndromic hearing loss. We identified a second family with inherited deafness that also maps to the DFNA4 region. To screen KPTN for deafness-causing mutations, we first determined its genomic structure and then completed a mutational analysis by direct sequencing and SSCP in affected family members. Although no deafness-causing mutations were identified in the coding region, KPTN remains an excellent candidate gene for hearing loss; by synteny, its murine orthologue also remains a candidate gene for the Nijmegan waltzer (nv) mouse mutant, which has vestibular defects and a variable sensorineural hearing loss.

Adult↗

PubMed2000

Neural electrophysiological studies on the external anal sphincter in children with anorectal malformation.

BACKGROUND/PURPOSE: Abnormality of innervation of external anal sphincter is one of the most important factors affecting postoperative anorectal function. The abnormalities of lumbosacral nerves have been reported in many radiological and histopathologic studies. There are few reports on the neurophysiological changes in children with anoractal malformation. The aim of this study was to examine the functional changes of nerves to the external anal sphincter in anorectal malformation. METHODS: Forty-five patients with anorectal malformation underwent studies of latencies of pudendo-anal reflex, spinoanal response, and evoked potential of cauda equine simultaneously. The conduction time of afferent nerve, efferent nerve, and sacral spinal center of pudendo-anal reflex arc were analyzed quantitatively. RESULTS: The latencies of pudendo-anal reflex, spino-anal response, and conduction time of sacral spinal center significantly are prolonged in patients with anorectal malformation (P< .05). There was significant difference between rectourethral fistula group and vestibular fistula group as well as low-type deformity group. The patients with lumbosacral anomalies such as lumbosacral spinal bifida or absence of S4 or S5 had prolonged latencies, especially the pudendo-anal reflex latency. There was significant negative correlation between the latencies and clinical scores. Although pudendoanal reflex latency was longer in patients who had posterior sagittal anorectoplasty than those who had abdominoperineal pull-through procedure, the difference was not significant. CONCLUSIONS: The abnormality of nerves to external anal sphincters is one of the important causes for clinical outcome. The neural lesions vary in each type of anal and lumbosacral deformity.

Adolescent↗

PubMed2000

Exercise training prevents maturation-induced decreases in insulin receptor substrate-1 and phosphatidylinositol 3-kinase in rat skeletal muscle.

We have previously reported that exercise training prevents a maturation-induced decrease in insulin sensitivity and suggested that an improvement of insulin sensitivity by exercise training was attributable, in part, to an increase in insulin-sensitive GLUT-4 on the skeletal muscle plasma membrane. In this study, we examined the effects of maturation and exercise training on the gene expression and protein content of the components of post-insulin receptor signal transduction in rat skeletal muscle. Rats aged 3 weeks were sedentary or trained by voluntary running through 4 or 27 weeks of age, and then the rats in both the sedentary and trained groups were killed and the gastrocnemius muscle was immediately removed for analysis of mRNA and protein content. The concentration of mRNA and protein for insulin receptor substrate-1 (IRS-1) in sedentary rats significantly decreased with maturation (49% and 63%, respectively, at age 27 weeks v age 4 weeks), but in trained rats they did not decrease with maturation. Although the level of phosphatidylinositol 3-kinase (PI 3-kinase) mRNA in sedentary rats was not altered with maturation, PI 3-kinase protein in sedentary rats significantly decreased with maturation (73% at 27 weeks v 4 weeks). However, PI 3-kinase protein in trained rats did not decrease with maturation. These results suggest that the prevention of maturation-induced decreases in the protein content of IRS-1 and PI 3-kinase is involved in the mechanisms responsible for the improvement of insulin sensitivity by exercise training, and exercise training may affect transcriptional regulation of the IRS-1 gene and posttranscriptional regulation of PI 3-kinase expression.

Animals↗

PubMed2000

Detection of lymph node metastasis of oesophageal cancer by RT-nested PCR for SCC antigen gene mRNA.

With recent development in molecular biology, reverse transcriptase polymerase chain reaction (RT-PCR) has been applied to detect occult lymph node metastasis, but there have been few reports concerning oesophageal cancer. The objective of this study is to investigate the usefulness of the squamous cell carcinoma (SCC) antigen gene as a marker with RT-nested PCR to detect occult lymph node metastases of oesophageal cancer. The SCC antigen has been widely used as a serum tumour marker and was reported as a target gene to detect tumour cells in peripheral blood in cervical cancer. In this study, 620 lymph nodes from 14 oesophageal cancer patients were analysed. The results of RT-nested PCR were compared with that of pathological and immunohistochemical examinations. In the test of sensitivity, the RT-nested PCR detected 10(1) of SCC antigen producing cells in 10(7) peripheral blood mononucleocytes and was not found in 43 control lymph nodes. The pathological examination, immunohistochemical examination and the RT-nested PCR detected 36, 45 and 65 nodes respectively. The RT-nested PCR detected statistically more lymph nodes than the pathological or immunohistochemical examination. The sensitivity and specificity seem higher in squamous cell carcinoma cases. The SCC antigen gene is one of the more useful markers for RT-nested PCR to detect occult lymph node metastases of oesophageal cancer.

Antigens, Neoplasm↗

PubMed2000

Induction of angiogenesis by cationic lipid-mediated VEGF165 gene transfer in the rabbit ischemic hindlimb model.

PURPOSE: The purpose of this study was to test the efficacy of a new cationic lipid formulation coupled with the cDNA encoding for the 165-residue form of vascular endothelial growth factor (VEGF(165)) to induce neovascularization and enhance blood flow in the rabbit ischemic hindlimb model. METHODS: Two days after removal of their right femoral arteries, rabbits received intramuscular injections of different concentrations of VEGF(165) or saline solution in the ischemic thigh. Tissue perfusion and increased neovascularization of the ischemic limb were assessed weekly on the basis of the calf blood pressure ratio for the ischemic/nonischemic limbs, regional blood flow to the skeletal muscles as measured with radioactive microspheres, postmortem angiography, and histology. RESULTS: At weeks 1 and 2 after surgery, animals treated with 1000 microgram of VEGF(165) had a 1.5-fold increase and a 2.5-fold increase, respectively, in the regional blood flow to both the adductor and gastrocnemius muscles of the ischemic limb. The blood pressure ratio was also greater in the treated animals than in the controls at weeks 2 and 3 after surgery. Early neovascularization in the VEGF(165) group was further documented at week 1 after surgery by more angiographically recognizable collateral vessels (angioscores were 64.13 +/- 2.51 and 38.28 +/- 3.82 for VEGF(165) and saline solution, respectively; P <.001) and by a threefold increase in the number of capillaries (vascular density) relative to the controls (P <.005). CONCLUSIONS: Intramuscular administration of a single dose of plasmid-liposomes encoding for VEGF(165) accelerates angiogenesis and increases blood flow in the rabbit hindlimb ischemic model. Therefore, this nonviral vector could be recommended for further testing for use in therapeutic angiogenesis.

Animals↗

PubMed2000

Cerebral palsy and multiple births in China.

BACKGROUND: A population-based study on prevalence of cerebral palsy in multiple births has not been carried out in China. The purpose of this paper was to determine the prevalence of cerebral palsy in multiple births and to explore the influence of multiple pregnancy on cerebral palsy after controlling for birthweight. METHODS: A cross-sectional study of cerebral palsy was carried out among 388,192 children aged <7 years in seven cities of Jiangsu province in China. Information about birthweight and plurality was obtained from routine health care records. Pediatricians at city level diagnosed all cases. All the doctors involved had taken part in a training programme held by Beijing Medical University. Stratified analysis by birthweight and its standard normal deviate was employed to compare the prevalence of cerebral palsy in multiples and singletons. RESULTS: The prevalence of cerebral palsy for children aged <7 years in multiples was 9.7 per 1000 children (95% confidence interval [CI]: 6.5-14.0), which was 6.5 times that in singletons (95% CI: 4.4-9.3). The overall neonatal mortality rate was 60.9 per 1000 liveborn multiples, being highest (944.4 per 1000) in the 500-999 g birthweight groups. Most liveborn multiples weighing <1500 g at birth probably died from diseases related to very low birthweight prior to this study. The prevalence of cerebral palsy in multiple births was likely to be higher than that reported in developed countries for children weighing 1500-2499 g even though our data were from a cross-sectional study. When stratified by birthweight, the prevalence of cerebral palsy in multiples weighing <2500 g had tended to be lower than that of singletons in the same birthweight group. In contrast, in normal birthweight categories multiple births had a higher prevalence of cerebral palsy than singletons. When stratified by birthweight normal deviate, the prevalence of cerebral palsy in multiple births was uniformly higher than that in singletons in all birthweight strata and the prevalence of cerebral palsy among multiples appeared to be augmented as birthweight increased. CONCLUSION: The prevalence of cerebral palsy in multiples, 9.7 per 1000 children, is 6.5 times that in singletons. Survival of low birthweight infants is lower in China than in developed countries and survival quality of Chinese children weighing 1500-2499 g needs to be further improved. In terms of birthweight multiples and singletons may be heterogeneous. It might be difficult to directly use actual birthweight specific prevalence to compare the prevalence of cerebral palsy in multiples and singletons. Birthweight normal deviate specific prevalence of cerebral palsy suggests that multiple pregnancy is an independent risk factor for cerebral palsy in all birthweight groups. Multiples are in adverse circumstances very early in gestation and as the foetus matures the risk of cerebral palsy increases.

Birth Weight↗