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Biomedical subjects

K Zhang

Publications and source records attributed to K Zhang.

At least 271 records · Page 15Linked to original sources
PubMed1997

[Long-term survival of fetal substantia nigra grafts in striatum of PD rats: an observation of tyrosine hydroxylase immunohistochemistry and western blot].

By using immunohistochemistry and Western blot, we observed the varied patterns of survival, development and growth of dopaminergic neurons after intrastriatal transplantation of fetal substantia nigra. There was a phenomenon of "developmental delay" of grafts in the host. As the time of transplantation went on, the grafted dopaminergic neurons could reinnervate the host neurons. The observation reveals that the reinnervation between graft and host is more beneficial to the functioning of the grafts.

Animals↗
PubMed1997

[Immunological rejection in rat embryonic brain tissue transplantation: experimental study].

The embryonic cerebral neocortex from rat or mouse donors which were 16 to 18-day-old embryos was grafted into the neocortex of adult recipient rats. One group was treated with cyclosporin A. At different time after transplantation, the brain graft tissues were stained immunocytochemically to exmine the expression of MHC-class II antigens and both subsets of T-cells, helper-inducer and cytotoxic-suppressor T-cells. The results indicated that the survival rate of treated group was higher than that of non treated with immunosuppressant. Immunocytochemical evaluation showed that a large number of helper T-cells and cytotoxic T-cells appeared, with a significant increase of the number of class II major histocompatibility complex (MHC) expressing cells within and around the allografts was observed. These MHC-class II antigen-positive cells may be lymphocytes, microglia and astrocytes. We conclude that the CNS is not a "immunologically privileged site" and there is graft rejection in brain transplantation. It is necessary for brain transplantation to be treated with immunosuppressant.

Animals↗
PubMed1997

[Intraparenchymal and intraventricular transplantation of fetal substantia nigra cell suspension in rat model of Parkinson's disease].

The grafts of fetal substantia cell suspension grafts could bring into a behavioral effect and characteristics of histology and immunocytochemistry in rat models of PD after the grafts were transplanted either into the lateral ventricles or directly into the striatum. It was found that the intraparenchymal tromsplantation of fetal nigral cell suspensions not only was beneficial to reinnervation between host and grafts, but also produced more complete and steady effects than the intraventricular transplantation. We concluded that the restoration of nervous functional deficits of PD rats is likely to depend on both extensive dopaminergic reinnervation throughout the grafted sites and on closer integration of the grafts with the host striatal circuitry.

Animals↗
PubMed1997

[The repair of injured brain by implanting embryonic cortical brain tissue preserved in Iloprost solution at 4 degrees C: experimental study].

We transplanted the fresh and Iloprost or saline preserved (3 hours) embryonic rat cortical brain tissue into the rats in which the motor cortex had been injured and compared the neurobehavioral and morphological changes. The neurobehavior of the transplanted groups was more significantly improved than that in the injured, untransplanted group. The neurobehavior of the animals of the fresh tissue group and Iloprost preserved group recovered to the preinjurylevel. The survival rate of the Iloprost preserved grafts was 90%, which was higher than that of the saline preserved grafts (P < 0.05). In comparison with the fresh grafts, however, there was no significant difference (P > 0.05). In addition, the growth volume of the Iloprost preserved grafts was more markedly increased than that of the fresh grafts (P < 0.01). We conclude that injured brain may be repaired effectively by transplantation of fetal brain cortex. The Iloprost solution not only maintains of vitality the grafts, but also promotes its survival and growth in the host brain.

Animals↗
PubMed1997

[Titanium plate reconstruction and fixation system for maxillofacial surgery: a synthetic clinical and experimental investigation].

Titanium plate-screw systems for maxillofacial reconstruction and internal fixation were studied including examination of chemical components, measurement of mechanical natures, biomechanical and biological evaluation, in combination with retrospective analysis of 319 cases fixed by means of plate-screw appliances. The results demonstrated that all experimental data have satisfied basically the design and clinical requirements, with the exception of a weaker curve-resistance and fixative stability of miniplate as well as lower surface wear-resistance of pure titanium. So, further improvement is necessary. Additionally, the function classification and indication of plate-screw systems are discussed. The duration and condition of intermaxillary fixation is suggested. The complications and their causes are analysed through comparison among different fixation systems.

Adolescent↗
PubMed1997

[Anatomy of the nasal cartilages of the unilateral lip and palate cleft nose].

Noses of 6 stillborn infants with unilateral lip and complete palate cleft were dissected and analysed. The surgical dissection revealed that the lower lateral cartilages are asymmetrical on both sides, indicating displacement of the lower lateral cartilages and the cartilageous septum which deviates to the normal side. Paired T Test shown that there is no significant difference between two sides in length and width. The conclusion is that the nasal deformities of the lip and palate cleft are congenital and one of the major causal factors is the displacement of lower lateral cartilages and cartilageous septum in the cleft side.

Abnormalities, Multiple↗
PubMed1997

[A preliminary study on the association between HLA-DPB1 gene and pathological myopia].

OBJECTIVE: To investigate the association between distribution of human leucocyte antigen class II DPB1 alleles and pathological myopia (PM) among Chinese. METHODS: The second exons of the HLA-DPB1 genes of 40 patients with PM were amplified by polymerase chain reaction (PCR), individual PCR products were digested by allele specific restriction enzymes: Bsp 1296 I, Fok I, Dde I, BsaJ I, BssH II, Rsa I, Ava II and EcoN I. Genotype of each patient was determined by restriction fragment length polymorphism (RFLP) pattern, then each DPB1 allele frequency of PM was calculated and compared with healthy control. RESULTS: The frequency of DPB1*0301 allele was significantly decreased in PM (Yates corrected chi 2 = 4.33, Fisher exacted P = 0.032 < 0.05) and no statistically significant difference was observed after P value was corrected by the number of compared alleles. The rate of DPB1*0501/0501 homozygote has a significant difference between PM and healthy controls (u = 2.27, P < 0.05). CONCLUSIONS: No genetic susceptible or resistant allele exists in HLA-DPB1 gene of PM. The significant increase of DPB1*0501/0501 homozygote in PM may be a linkage information.

Adolescent↗
PubMed1997

[Determination of trace silver in surface water samples by flame atomic absorption with continuous flow on-line absorption preconcentration].

In a continuous flow on-line preconcentration system, trace silver was adsorbed onto activated carbon particles packed in micro colum at pH 1, eluted with 0.3 ml of 10 g/L Na2S2O3 solution and determined by flame atomic absorption spectrometry. For surface water samples, 25 ml sufficed precise determination of silver at level of microgram/L. The relative standard deviation of 10 parallel sample determinations was 6.9%. The proposed method was successfully applied to water samples with recoveries ranging from 93.2% to 104.6% and a throughout of 7-8 sampling/h.

Silver↗
PubMed1997

[Adsorption of permanganate onto activated carbon particles].

In this paper, the adsorption behavior of permanganate onto activated carbon particles was studied as a function of pH, flow rate and the concentration of permanganate. It was found that permanganate was not adsorbed but reduced by activated carbon particles. The percent of reduction of permanganate was strongly pH-dependent. The reducing product of permanganate was mainly Mn2+ which was adsorbed onto the activated carbon particles by surface complexation.

Adsorption↗
PubMed1997

[Preliminary evaluation of plastic crown restoration supported by osseointegrated implants].

This study was to evaluate the feasibility of plastic crown restoration supported by osseointegrated implants. The following conclusions were drawn from this study: plastic crown gave better biomechanical consideration than porcelain fused to metal (PFM) crown in osseointegrated prostheses, but plastic crown gave worse wearability, tensile strength, compression strength and flexuaral strength than PFM crown. After restoration the disadvantages of the plastic crown were beyond the clinical acceptable range. It showed plastic crown designed dental prothetic implantation was unfeasible.

Crowns↗
PubMed1997

Antisense oligonucleotides fail to inhibit the expression of central beta adrenergic receptors.

A number of antisense phosphorothioate oligodeoxynucleotides (ODNs) targeted to different regions of mRNAs were tested for their ability to inhibit the expression of central beta adrenergic receptors (ARs). None of these antisense ODNs reduced beta AR density. By contrast, a dopamine D2 receptor antisense ODN did decrease striatal D2 receptor density. The recovery of beta AR density after down-regulation was not altered by any of the antisense ODNs tested. Moreover, the response of rats under a DRL 72-sec schedule to clenbuterol, a beta-2 selective AR agonist, was not attenuated by chronic treatment with a beta-2 AR antisense ODN.

Adrenergic beta-Agonists↗
PubMed1997

Extremely low awareness of AIDS, sexually transmitted diseases and condoms among Dai ethnic villagers in Yunnan province, China.

OBJECTIVE: To assess the awareness of AIDS, other sexually transmitted diseases (STDs), condoms, sources of health information and HIV-related societal risks among Dai villagers in southern Yunnan Province, China. SUBJECTS AND METHODS: In November-December 1994, a cross-sectional descriptive study, comprising a questionnaire-based survey and focus group discussions, was conducted in three Dai villages in Mengla county; a total of 177 Dai villagers were interviewed in the survey and eight focus group discussions were held. Ethnographic observations provided a composite picture of HIV risks in the area. RESULTS: Only 18% of respondents had heard of AIDS, and only 25 and 28%, respectively, had heard of STDs or condoms. Furthermore, among these more aware groups, the level of knowledge was low and misconceptions were common. An ability to understand the official language (Mandarin) was the most important predictor of awareness of AIDS, other STDs or condoms. The sources of information in the three Dai villages sampled included TV, videos, radio and magazines, but only TV and videos had a large audience. Even so, these media were mostly in Mandarin and were not used in AIDS education. Travel outside of China was frequent; most villagers (77%) had traveled to Laos and 9% had traveled to Thailand. Societal risks of HIV transmission, such as an increasing incidence of STDs and an active sex industry, were observed in this area. CONCLUSIONS: Dai villagers in southern Yunnan Province had an extremely low awareness and knowledge of AIDS, other STDs and condoms. Given the high mobility of ethnic villagers to neighboring countries in Southeast Asia and the societal risks of HIV transmission in this area, there is an urgent need to provide accessible education about AIDS and other STDs. Suggestions regarding such health education and the implications of HIV policy-making are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Construction of mammary gland-specific expression vectors for human clotting factor IX and its secretory expression in goat milk.

Two expression vectors comprised of mouse matrix attachment regions (MARs), bovine beta-casein gene sequence, human factor IX (hFIX) minigene, and cDNA, pMCIXm and pMCIX, were constructed for the purpose of a mammary gland bioreactor. A secretory expression system of hFIX protein in milk was made using stearylamine (SA) liposome to transfect plasmid DNA directly into the mammary gland lobule of a lactating goat. The highest production of hFIX in goat milk was 13.7 ng/ml 3 days after transfection, and the hFIX production in the goat mammary gland transfected with pMCIXm containing hFIX minigene was obviously higher than that transfected with pMCIX containing hFIX cDNA. Activity immuno-analysis and the barium citrate absorption method showed that > 90% hFIX protein in milk appeared to be a gamma-glycosylated and biological activity. This result confirmed the validity of the constructed vectors for further transgenic study, and this assay could also find its success in the evaluation of a foreign gene expression and secretion in the milk as a rapid detection system using liposome to transfect DNA directly into the goat mammary gland.

Animals↗
PubMed1997

Pronounced antitumor effects and tumor radiosensitization of double suicide gene therapy.

The efficacy of HSV-1 thymidine kinase (TK) and Escherichia coli cytosine deaminase (CD) suicide gene therapies as cancer treatments are currently being examined in humans. We demonstrated previously that compared to single suicide gene therapy, greater levels of targeted cytotoxicity and radiosensitization can be achieved in vitro by genetically modifying tumor cells to express CD and HSV-1 TK concomitantly, as a fusion protein. In the present study, the efficacy of the combined double suicide gene therapy/radiotherapy approach was examined in vivo. Nude mice were injected either s.c. or i.m. with 9L gliosarcoma cells expressing an E. coli CD/HSV-1 TK fusion gene. Double suicide gene therapy using 5-fluorocytosine (500 mg/kg) and ganciclovir (30 mg/kg) proved to be markedly better at delaying tumor growth and achieving a tumor cure than single suicide gene therapy, which used 5-fluorocytosine or ganciclovir administered independently. Importantly, double suicide gene therapy was highly effective against large experimental tumors (>2 cm3), reducing tumor volume an average of 99% and producing a 40% tumor cure. Moreover, double suicide gene therapy profoundly potentiated the antitumor effects of radiation. The results indicate that double suicide gene therapy, particularly when coupled with radiotherapy, may represent a highly effective means of eradicating tumors.

Animals↗
PubMed1996

The relationship between human epidermal growth-like factor receptor expression and cellular transformation in NIH3T3 cells.

A collection of cell lines expressing each human epidermal growth factor receptor (HER) family member alone or in all pairwise combinations in a clone of NIH3T3 cells (3T3-7d) devoid of detectable epidermal growth factor receptor family members has been generated. Transformation, as measured by growth in soft agar, occurred only in the presence of appropriate ligand and only in cells expressing two different HER family members. Transfection of oncogenic neu (Tneu), conferred ligand-independent transformation only in cells which co-expressed HER1, HER3, or HER4, but not when expressed alone or with HER2. Cell lines were also tested for their ability to form tumors in animals. None of the cell lines expressing single HER family members was able to form tumors in animals with the exception of HER1, which was weakly tumorigenic. Although unable to form tumors when expressed alone, HER2 was tumorigenic when expressed with HER1 or HER3, but not HER4. Of all complexes analyzed, cells expressing HER1 + HER2 were the most aggressive. The relationship between HER1 activation, intracellular calcium fluxes, and phospholipase Cgamma1 activation is well established. We found that activation of HER1 was required for the induction of a calcium flux and the phosphorylation of phospholipase Cgamma1. These activities were independent of, and unaffected by, the co-expression of any other family member. Further, heregulin stimulation of all cell lines including those containing HER1 did not demonstrate any effect on intracellular calcium levels or phospholipase Cgamma1 phosphorylation. This demonstrates that heregulin induced cellular transformation by activating HER3- and HER4-containing complexes does not require the activation of either phospholipase Cgamma1 or the mobilization of intracellular calcium.

3T3 Cells↗
PubMed1996

Inhibition of the efflux of glutathione S-conjugates by plant polyphenols.

The formation of dinitrophenylglutathione (DNP-SG) in human colon adenocarcinoma cells was identified and quantified by an HPLC-UV method, following exposure to 1-chloro-2,4-dinitrobenzene (CDNB) at 10 degrees for 40 min. The rate of efflux of DNP-SG at 37 degrees likewise, was measured by monitoring the DNP-SG content in the extracellular medium. Among the polyphenols examined for their action on DNP-SG export, butein was the most potent inhibitor with an IC50 value of 15 microM. The others, in order of decreasing potencies, were quercetin, tannic acid, 2'-hydroxychalcone, 2-hydroxychalcone anIIC50 values in the micromolar range. These polyphenols did not affect the ATP or the glutathione content of the cells. Mg(2+)-ATPase extracted from the plasma membrane of the cells was activated by DNP-SG in a concentration-dependent manner, and the reaction showed saturation kinetics with K(m) and Vmax values of 110 microM and 12.3 nmol/min/mg protein, respectively. However, the six polyphenols mentioned above had negligible effects on the Mg(2+)-ATPase activity, suggesting that this was probably not the target of their inhibitory action. Probenecid, p-trifluoromethoxy-phenylhydrazone (FCCP) and chlorambucil also showed varying degrees of inhibition of the export of DNP-SG.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

D-Phe complexes of zinc and cobalt carboxypeptidase A.

The binding of D-phenylalanine, D-Phe, to both zinc and cobalt carboxypeptidase A, ZnCPD and CoCPD, has been investigated by a combination of kinetic and spectroscopic techniques. Kinetic studies of the ZnCPD catalyzed hydrolysis of dansyl-Gly-Ala-L-Phe indicate that D-Phe inhibition occurs through a two-site sequential competitive inhibition mode with Ki values of 45 microM and 11.6 mM at pH 8.4, 1 M NaCl, 25 degrees C. Spectral titration of CoCPD under the same conditions indicates a very strong binding mode of D-Phe (KD < 100 microM) that only slightly perturbs the visible cobalt electronic transitions. However, the conversion of CoCPD.D-Phe into a CoCPD.D-Phe2 (KD, 1.13 mM) is accompanied by a very strong spectral perturbation resulting in a complex that is characterized by Amax values of 506 nm (epsilon = 27 M-1 cm-1) and 605 nm (epsilon = 17 M-1 cm-1) and a shoulder at 530 nm (epsilon = 23 M-1 cm-1). The spectral properties of this ternary complex differ markedly from that of the CoCPD.L-Phe.N3-ternary complex. X-ray absorption fine structure, XAFS, studies indicate that these differences are likely due to a more regular tetrahedral coordination sphere for the ternary azide complexes compared to an octahedral coordination geometry for the Zn and CoCPD.D-Phe2 complexes.

Animals↗