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Biomedical subjects

K Zhang

Publications and source records attributed to K Zhang.

At least 199 records · Page 11Linked to original sources
PubMed1999

[A case-control study on Guillain-Barre syndrome in children of North China].

OBJECTIVE: This study aimed at exploring the risk factors for Guillain-Barre syndrome (GBS). METHODS: A case-control study design was used with 51 cases of GBS, diagnosed based on their symptoms, signs and electrophysiological examinations and exclusion of poliomyelitis and other acute flaccid paralysis, and 51 controls matched on age, sex and resident village. Serum IgG antibodies specific for Campylobacter jejuni were determined for all the subjects by enzyme-linked immunosorbent assay (ELISA) with a preparation of surface antigen of C. jejuni C(1) strain isolated from the patients and prevalent in north China. Each case and control were interviewed with his/her parents or guardians by a trained interviewer using an ad hoc questionnaire, including his/her demographic information, socioeconomic status, onset of the illness, and potential risk factors in their environment and personal hygiene. Data were analyzed with SAS software release 6.04 in a microcomputer. RESULTS: GBS was associated with a few factors, such as residential areas (45 of the 51 cases living in the rural areas, accounting for 88.2% of the total), polio and hepatitis B vaccine immunization before onset of the illness (with ORs of 7.27 and 3.14, respectively), no hand washing after defecation and before meals (with an OR of 6.15) and getting cold and going to the river or lake site before onset of the illness (with ORs of 13.75 and 12.20, respectively). Infection with Campylobacter jejuni associated strongly with the illness (with an OR of 9.5, P < 0.001). Thirty-five of the 51 cases had precursor symptoms before onset of the illness (68.6%). CONCLUSION: It suggests that occurrence of GBS may correlate to infection with Campylobacter jejuni and poor personal hygiene in children.

Antibodies, Bacterial↗
PubMed1999

[A study on relationship between hypertension and polymorphism of ACE gene in male Yi people in Liangshan Yi autonomous prefecture, Sichuan].

OBJECTIVE: To explore relationship between polymorphism of ACE gene and hypertension. METHODS: A cross-sectional study was conducted and PCR technique was used to analyze gene polymorphism. RESULTS: Genotypes DD, ID and II of ACE gene accounted for 13.0% and 9.7%, 50.9% and 48.4%, and 36.1% and 41.9%, respectively, in the normotensives and hypertensives. Frequencies of I and D alleles for ACE gene were 61.6% and 66.1%, and 38.4% and 33.9%, respectively, in the normotensives and hypertensives. There was no significant difference in distribution of II, ID and DD genotypes and I/D allele frequencies of ACE gene between the hypertensives and normotensives in male Yi people. CONCLUSION: Association between polymorphism of ACE gene and hypertension was uncertain.

Adult↗
PubMed1999

[Effect of gui xin tong on sorbitol and nerve conduction velocity in diabetic rats].

OBJECTIVE: To investigate the effect of Gui Xin Tong(GXT) on sorbitol and nerve conduction velocity in diabetic rats. METHOD: The model rats suffering from diabetes were induced by STZ, and blood sugar levels above 16 mmol/L were chosen for observation. The rats were divided into GXT group, AG group and control group. The nerve conduction velocity, aldose reductase activity and sorbitol in STZ induced diabetic rats were investigated. RESULT: Compared with the control group GXT could increase the sciatic nerve conduction velocity significantly (P < 0.05), decrease the RBC and sciatic nerve, aldose reductase activity, and RBC-sorbitol content. CONCLUSION: GXT has the effect of improving nerve conduction velocity significantly and reducing aldose reductase activity and sorbitol

Aldehyde Reductase↗
PubMed1999

[The study of carbonaceous adsorbent for solid-phase microextraction and the comparison with commercial device].

The parameters governing solid-phase microextraction have been investigated, and the development of carbonaceous adsorbent for SPME is presented because it is durable and inexpensive. The time profile curves were determined for several organic pesticides having a wide range of water solubilities and the effect of salt was also investigated. The method of SPME-GC-ECD to analyse trace level of the organic pesticide in water is established by the determination of optimum parameters. The comparison with commercial SPME device shows that the carbonaceous adsorbent having been treated with physical or chemical method for SPME can get lower limits of detection than polyacrylate and polydimethylsiloxane, although there are still some work to be done to improve its precision. The results shows that this new SPME device has great application potential.

Acrylic Resins↗
PubMed1999

[Taxonomy of the producing strain of agricultural antibiotic 2-16].

In screening process of new agricultural, a streptomycetes, 2-16, was isolated from the soil sample collected in Huangsan. The secondary metabolites produced by the strain had strong inhibition to Sclerotinia sclerotiorum. By identification, this strain was regarded as new variety of Streptomyces ahygroscopicus and was called Streptomyces ahygroscopicus var. huangsanensis.

Agrochemicals↗
PubMed1999

[The relation of fetal growth and the biological risk factors of coronary heart disease].

OBJECTIVE: To examine the relationship between fetal growth and the biological risk factors of coronary heart disease (CHD) in adult life in China. METHODS: Follow up stuty of 628 men and women who were singleton born during 1948-1954 whose birth size were measured in detail. RESULTS: Decreasing birth weight increased the probability of myocardial ischaemic symptom related to CHD (beta = -0.0018, P < 0.01). The Odds ratio (OR) related to hypertension increased with decreasing birth weight and ponderal index (PI, kg/m3). The OR were 5.9 in people whose PI were 24 kg/m3 or less compare to people whose PI were more than 28 kg/m3. The OR related to impaired glucose tolerance(IGT) also increased with decreasing birth weight and PI. Insulin resistance, represented by fast insulin, rose with decreasing birth weight and head circumference(for trend, all P < 0.01). Serum TG concentration significantly rose with decreasing birth weight, PI and head circumference (for trend, P < 0.01, P < 0.01, P < 0.05), while HDL-C rose with increasing birth weight and head circumference (for trend, P < 0.05, P < 0.01). All above mentioned relations between birth size and the level of risk factors during adulthood were independent of gestation and adult lifestyle. CONCLUSIONS: In China, low birth measurements which represent the fetal growth retardation might contribute to the present of biological risk factors of coronary heart disease during adulthood, such as hypertension, diabetes, insulin resistance, high serum triglyceride and low HDL-C.

Birth Weight↗
PubMed1999

[Effect of dialysates on ultrastructure of mouse peritoneal mesothelium].

OBJECTIVE: To observe the effect of various peritoneal dialysates on the ultrastructure of the peritoneal mesothelium. METHODS: Continuous ambulatory peritoneal dialysis mice model was made by injecting domestic lactate, acetate, and American Baxter dialysates intraperitoneally. The diaphragmatic peritoneum of the mice was taken at 10th day and 21th day respectively after injection. RESULTS: After 10 day experiment, the mesothelial ultrastructure of Baxter group was normal, but some pathological changes occurred in the peritoneal mesothelium of both domestic lactate and acetate groups. And the injury of the peritoneal mesothelium was progressing with times, e.g. adhesion and exfoliation of the microvilli, shrinkage of the mesothelial cells and even fibrous adhesion. The extent of effects on the mesothelial cells varied in three groups, the least is Baxter group. After 21 day experiments, the diameters of the stomata were (6.96 +/- 2.46) microns and (6.98 +/- 2.16) microns in both domestic lactate and acetate dialysates groups respectively, which were much greater than those in physiological condition (1.47 +/- 0.88) microns (P < 0.01). The distribution density of the lymphatic stomata were significantly increased in acetate and lactate dialysate groups compared with the control group (P < 0.01). But little effects on the lymphatic stomata were showed after using Baxter dialysate. After discontinuing experiment for 10 days, the impairment of the peritoneal mesothelium recovered in Baxter group and improved to varying degrees in both domestic dialysate groups. The lymphatic stomata were still abnormal in both domestic dialysate groups. CONCLUSIONS: Our findings indicate that lactate and acetate dialysates are more like to elicit peritoneal fibrosis and the increase of distribution density and the enlargement of the lymphatic stomata can significantly enhance their absorption effects and increase their reabsorption quantity of dialysate from the peritoneal cavity during peritoneal dialysis. These changes of the lymphatic stomata and their lymphatic reabsorption are thought to be associated with deterioration of peritoneal function, and to cause ultrafiltration failure in the patients on long-term continuous ambulatory peritoneal dialysis (CAPD) therapy.

Acetates↗
PubMed1999

[Identification study on pig's hoofnail].

The identification characteristics of pig's hoofnail on properties and tissue slice was initially probed from the viewpoint of identification in this paper in order to make basis for the systematic research on replacing Squama manitis.

Animals↗
PubMed1998

[Identification of adhalin gene mutation in limb-girdle muscular dystrophy in Chinese].

OBJECTIVE: Limb-girdle muscular dystrophy (LGMD) is a group of severe genetic heterogeneity muscular diseases characterized by proximal muscular weakness of the pelvis and shoulder, affecting both male and female. This group of diseases involves four gene loci (13q12, 17q21,4q12,5q33). Up till now there is no research report about LGMD in Chinese. This study was intended to identify the pathogenic genes of LGMD in Chinese by mutation detecting. METHODS: The exons 2 and 3 of adhalin gene were analyzed in 13 Chinese LGMD patients and 20 controls by using PCR-SSCP and DNA sequencing. RESULTS: The R77C (Arg77Cys) missense mutation was found at the two alleles of a 9-year-old LGMD girl, which had not been found in the 40 wild type chromosomes. This is the first report on adhalin mutation that exists in LGMD in Chinese. CONCLUSION: Our results suggest that adhalin gene is one of the predisposing genes in LGMD in Chinese.

Child↗
PubMed1998

2',5'-Oligoadenylate-antisense chimeras cause RNase L to selectively degrade bcr/abl mRNA in chronic myelogenous leukemia cells.

We report an RNA targeting strategy, which selectively degrades bcr/abl mRNA in chronic myelogenous leukemia (CML) cells. A 2', 5'-tetraadenylate activator (2-5A) of RNase L was chemically linked to oligonucleotide antisense directed against either the fusion site or against the translation start sequence in bcr/abl mRNA. Selective degradation of the targeted RNA sequences was demonstrated in assays with purified RNase L and decreases of p210(bcr/abl) kinase activity levels were obtained in the CML cell line, K562. Furthermore, the 2-5A-antisense chimeras suppressed growth of K562, while having substantially reduced effects on the promyelocytic leukemia cell line, HL60. Findings were extended to primary CML cells isolated from bone marrow of patients. The 2-5A-antisense treatments both suppressed proliferation of the leukemia cells and selectively depleted levels of bcr/abl mRNA without affecting levels of beta-actin mRNA, determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The specificity of this approach was further shown with control oligonucleotides, such as chimeras containing an inactive dimeric form of 2-5A, antisense lacking 2-5A, or chimeras with altered sequences including several mismatched nucleotides. The control oligonucleotides had either reduced or no effect on CML cell growth and bcr/abl mRNA levels. These findings show that CML cell growth can be selectively suppressed by targeting bcr/abl mRNA with 2-5A-antisense for decay by RNase L and suggest that these compounds should be further explored for their potential as ex vivo purging agents of autologous hematopoietic stem cell transplants from CML patients.

Adenine Nucleotides↗
PubMed1998

Transcription factors Sp1 and Sp3 alter vascular endothelial growth factor receptor expression through a novel recognition sequence.

Kinase domain receptor (KDR) is a high affinity, endothelial cell-specific, autophosphorylating tyrosine kinase receptor for vascular endothelial growth factor. This transcriptionally regulated receptor is a critical mediator of endothelial cell (EC) growth and vascular development. In this study, we identify a DNA element modulating KDR promoter activity and evaluate the nuclear binding proteins accounting for a portion of the cell-type specificity of the region. KDR promoter luciferase activity was retained within -85/+296 and was 10-30-fold higher in EC than non-EC. Electrophoretic mobility shift assays demonstrated specific nuclear protein binding to -85/-64, and single point mutations suggested important binding nucleotides between -79/-68 with five critical bases between -74/-70 (5'-CTCCT-3'). DNA-protein complexes were displaced by Sp1 consensus sequence oligodeoxynucleotides and supershifted by Sp1- and Sp3-specific antibodies. Sp1 and Sp3 protein in EC nuclear extracts bound the -79/-68 region even when all surrounding classic Sp1 recognition sites were removed. Sp1 protein in nuclear extracts was 4-24-fold higher in EC than non-EC, whereas Sp3 was 3-7-fold higher. Sp1/Sp3 ratios in EC were 2-10-fold higher. Overexpression of Sp1 protein increased KDR promoter activity 3-fold in both EC and non-EC, whereas simultaneous co-expression of Sp3 attenuated this response. An Sp1 consensus sequence cis element "decoy" reduced EC KDR promoter activity and mRNA expression by 85 and 69%, respectively. An antisense phosphorothioate oligodeoxynucleotide to Sp1 inhibited Sp1 and KDR protein expression by 66 and 68%, respectively, without changing Sp3 protein expression. These data illustrate that Sp1 and Sp3 modulate KDR promoter activity through a novel recognition binding sequence. However, since Sp1-mediated promoter activation is attenuated by Sp3, endothelial selective KDR promoter activity may be partially regulated by variations in the Sp1/Sp3 ratio.

Base Sequence↗
PubMed1998

Myelin Po protein mutated at Cys21 has a dominant-negative effect on adhesion of wild type Po.

The homophilic adhesion of the peripheral nervous system myelin protein, Po, holds myelin compact at the extracellular leaflets. Po carries a single immunoglobulin (Ig)-like domain that is stabilized by a disulfide bond between Cys21 and Cys98. We showed previously that Po mutated at Cys21 to Ala (C21A Po), unlike wild type Po, when it was expressed in Chinese hamster ovary (CHO) cells after transfection, was not adhesive. To determine whether C21A Po could influence the adhesion of wild type Po, cells that already expressed wild type Po and that were shown to be adhesive were retransfected with plasmids containing C21A Po. After selection in hygromycin, clones that coexpressed wild type Po and Cys21-mutated Po were identified by polyacrylamide gel electrophoresis in the presence and absence of beta-mercaptoethanol, because only in coexpressors will there be two forms of Po of different apparent molecular weights under nonreducing conditions. Two clones that coexpressed wild type Po and C21A Po and a third clone, which, although it was resistant to hygromycin, expressed only wild type Po, were chosen for further study. An enzyme-linked immunosorbent assay of fixed, unpermeabilized cells showed that all of these clones expressed approximately equivalent amounts of Po at the cell surface. However, in an aggregation adhesion assay, only the cells that expressed wild type Po alone formed large aggregates and dropped in total particle number with time. The cells that coexpressed wild type and C21A Po did not form aggregates, and their adhesive properties were indistinguishable from the control transfected cells, which did not express Po. These results suggest that C21A Po has a dominant-negative effect on adhesion of wild type Po.

Animals↗
PubMed1998

Energy-resolving X-ray fluorescence detection using synthetic multilayers.

The potential of synthetic multilayers for energy-resolving the X-ray fluorescence in X-ray absorption fine structure (XAFS) experiments is discussed. Two detection systems, one using curved multilayers and the other using graded multilayers to select X-ray fluorescence photons, have been designed to cover a wide energy range with a usefully large solid angle. Such a detector will be more advantageous than the barrel-like crystal-array detector because of the unique properties of synthetic multilayers, such as larger horizontal acceptance angles and bandwidth. In addition, the detector should be much simpler to construct and readily accommodates energy changes, especially the detector using graded multilayers. Comparison of the multilayer array detector with conventional detectors, such as ionization chambers and conventional 13-element Ge detectors, shows that the proposed system will be superior, particularly with the increased photon fluxes available from insertion devices and with decreased sample concentration, since this detection system eliminates the ;bad' photons before they enter any X-ray detector. Consequently, the X-ray detector proper for this system does not suffer from the incident-count-rate bottleneck common to current X-ray fluorescence detectors with energy resolution by signal processing. Thus, this new fluorescence detection system will provide tremendous opportunities for XAFS measurements on dilute systems, such as biological systems, at third-generation synchrotron sources.

Journal Article↗
PubMed1998

Butein, a specific protein tyrosine kinase inhibitor.

Butein, a plant polyphenol, was shown to be a specific protein tyrosine kinase inhibitor. This compound inhibited not only the epidermal growth factor (EGF)-stimulated auto-phosphotyrosine level of EGF receptor in HepG2 cells but also tyrosine-specific protein kinase activities of EGF receptor (IC50 = 65 microM) and p60c-src (IC50 = 65 microM) in vitro. The inhibition was competitive to ATP and non-competitive to the phosphate acceptor, poly (Glu, Ala, Tyr) 6:3:1 for EGF receptor tyrosine kinase. In contrast, butein non-significantly inhibited the activities of serine- and threonine-specific protein kinases, such as protein kinase C (PKC) and cAMP-dependent protein kinase (PKA).

CSK Tyrosine-Protein Kinase↗
PubMed1998

Guanylate-cyclase-inhibitory protein is a frog retinal Ca2+-binding protein related to mammalian guanylate-cyclase-activating proteins.

Two guanylate-cyclase-activating proteins (GCAP) encoded by a tail-to-tail gene array have been characterized in the mammalian retina. Using frog retina as a model, we obtained evidence for the presence of a photoreceptor Ca2+-binding protein closely related to GCAP. This protein (206 amino acids) does not stimulate guanylate cyclase (GC) in low [Ca2+], but inhibits GC in high [Ca2+], and is therefore termed guanylate-cyclase-inhibitory protein (GCIP). Sequence analysis indicates that GCIP and GCAP1 and GCAP2 have diverged substantially, but conserved domains present in all vertebrate GCAP are present in GCIP. Moreover, partial characterization of the GCIP gene showed that the positions of two introns in the GCIP gene are identical to positions of corresponding introns of the mammalian GCAP gene array. As to the major differences between GCIP and GCAP, the fourth EF hand Ca2+-binding motif of GCIP is disabled for Ca2+ binding, and GCIP does not stimulate GC. Monoclonal and polyclonal antibodies raised against recombinant GCIP identified high levels of GCIP in the inner segments, somata and synaptic terminals of frog cone photoreceptors. The results suggest that GCIP is a Ca2+-binding protein of the GCAP/recoverin subfamily. Its localization in frog cones closely resembles that of GC in mammalian cones. GCIP inhibits GC at high free [Ca2+], competing with GCAP1 and GCAP2 for GC regulatory sites.

Amino Acid Sequence↗
PubMed1998

Altered number of diaphorase (NOS) positive neurons in the hypothalamus of rats with heart failure.

Recently, we have demonstrated a decreased neuronal isoform of nitric oxide synthase (nNOS) message in the hypothalamus of rats with heart failure (HF). The purpose of this study was to determine the changes in NADPH-diaphorase (a commonly used marker for neuronal NOS activity) positive neurons in specific hypothalamic sites of rats with HF. After a standard histochemical protocol, NOS positive neurons were measured in paraventricular nucleus (PVN), supraoptic nucleus (SON), median preoptic area (MePO), subfornical organ (SFO), organum vasculosum of the lamina terminalis (OVLT) and lateral hypothalamus (LH) of rats with coronary artery ligation (HF group; n=8) and sham-operated control rats (n=9). A total of 4 months after coronary ligation, the rats in the HF group displayed infarcts greater than at least 35% of the left ventricular wall (n = 8). Sham-operated rats had no observable damage to the myocardium. Rats with HF had a significantly lower number of NOS positive cells in the PVN (36% less) compared to sham rats. The number of NOS positive cells remained unaltered in the SON, MePO and LH in rats with HF. Conversely there was an increased number of NOS positive cells in the SFO (42% greater) and OVLT (100% greater). These data support the conclusion that the NO system within the hypothalamus involved in controlling autonomic outflow is altered during HF and may contribute to the elevated levels of vasopressin and sympatho-excitation commonly observed in HF.

Animals↗
PubMed1998

Statistically efficient estimation using population coding.

Coarse codes are widely used throughout the brain to encode sensory and motor variables. Methods designed to interpret these codes, such as population vector analysis, are either inefficient (the variance of the estimate is much larger than the smallest possible variance) or biologically implausible, like maximum likelihood. Moreover, these methods attempt to compute a scalar or vector estimate of the encoded variable. Neurons are faced with a similar estimation problem. They must read out the responses of the presynaptic neurons, but, by contrast, they typically encode the variable with a further population code rather than as a scalar. We show how a nonlinear recurrent network can be used to perform estimation in a near-optimal way while keeping the estimate in a coarse code format. This work suggests that lateral connections in the cortex may be involved in cleaning up uncorrelated noise among neurons representing similar variables.

Computer Simulation↗