Search PubMed⌕ Search

Biomedical subjects

K Zhang

Publications and source records attributed to K Zhang.

At least 91 records · Page 5Linked to original sources
PubMed2001

Modulation of cisplatin cytotoxicity and cisplatin-induced DNA cross-links in HepG2 cells by regulation of glutathione-related mechanisms.

Glutathione (GSH), glutathione S-transferase (GST), and glutathione conjugate export pump (GS-X pump) have been shown to participate collectively in the detoxification of many anticancer drugs, including cisplatin. Identification and regulation of the rate-limiting step in the overall system for cisplatin detoxification is of crucial importance for sensitization of human tumor cells to cisplatin. In this study, the GSH content, GST activity, and GS-X pump activity were regulated separately to examine effects of the regulation on cisplatin cytotoxicity and cisplatin-induced DNA interstrand cross-links (ICL) in HepG2 cells. Seventy-percent depletion of GSH by buthionine sulfoximine (BSO) and 50% increase of GSH by monoethyl GSH ester (GSHe) potentiated and decreased cisplatin cytotoxicity, respectively. This was reflected by a significant decrease and increase of their respective IC(50) values by 62 and 107%. Cisplatin-induced ICL was also potentiated by depletion of GSH by BSO and decreased by enrichment of GSH by GSHe, as shown by a 125% increase and a 34% decrease of cross-linked DNA compared with control samples exposed to cisplatin alone (p = 0.008 and 0.03, respectively). On the other hand, inhibition of GST and GS-X pump by ethacrynic acid, quercetin, tannic acid, and indomethacin at concentrations that inhibited activities of GST and GS-X pump by more than 50% had no significant effects on cisplatin cytotoxicity and cisplatin-induced DNA ICL in these cells. The results showed that of the parameters measured, intracellular GSH seems to be the rate-limiting factor, and its regulation would provide a more promising strategy for sensitization of human liver tumor cells to cisplatin.

Biological Transport↗
PubMed2001

Blunted nitric oxide-mediated inhibition of renal nerve discharge within PVN of rats with heart failure.

We have demonstrated a decreased neuronal nitric oxide (NO) synthase (nNOS) message in the hypothalamus of rats with heart failure (HF). Subsequently, we have demonstrated that NADPH diaphorase (a commonly used marker for nNOS activity) positive neurons are decreased in paraventricular nucleus (PVN) of rats with coronary artery ligation model of HF. The goal of the present study was to examine the influence of endogenous NO within the PVN on renal sympathetic nerve discharge (RSND) during HF. In alpha-chloralose- and urethane-anesthetized rats, an inhibitor of NO synthase, N(G)-monomethyl-L-arginine (L-NMMA) microinjected into the PVN (50, 100, and 200 pmol in 50-200 nl) produced a dose-dependent increase in RSND, blood pressure, and heart rate in control and HF rats. These responses were attenuated in rats with HF compared with control rats. On the other hand, the NO agonist, sodium nitroprusside, microinjected in PVN produced a dose-dependent decrease in RSND and blood pressure in control and HF rats. These responses were less in rats with HF compared with control rats. These data suggest that the endogenous NO-mediated effect within the PVN of HF rats is less potent in suppressing RSND compared with control rats. These data support the conclusion that the NO system within the PVN involved in controlling autonomic outflow is altered during HF and may contribute to the elevated levels of renal sympathoexcitation commonly observed in HF.

Animals↗
PubMed2001

A method for accurate detection of translocation junctions in Ewing family of tumors.

The Ewing family of tumors (ET) generally contain translocations involving the EWS gene and the FLI or ERG genes. Identification of the translocation confirms the diagnosis of ET. Currently, diagnosis of the translocation is made by several methods. In general, these methods require different primer sets for amplifying different translocations and subsequent efforts to identify the amplified product. The need to employ different sets of primers to amplify different translocation junctions presents some limitations. We have developed a method based on PCR with consensus primers followed by direct automated sequencing of the amplified product. With this method we have correctly determined known as well as unknown ET-associated EWS-FLI and EWS-ERG translocations in appropriate specimens. Use of our consensus primers eliminates the need for separate PCRs to amplify EWS-FLI and EWS-ERG translocation junctions, and because direct sequencing is used for confirming the identity of the amplification product, the accuracy of detection becomes 100%. The method might also accurately diagnose ET-associated translocations other than EWS-FLI and EWS-ERG translocations.

Amino Acid Sequence↗
PubMed2001

Microsatellite alterations in human hepatocellular carcinoma infected with hepatitis B virus: associated with the elevation of serum alpha-fetoprotein.

Identification of the basic genetic changes in human hepatocellular carcinoma (HCC) is very important for the understanding of this cancer. In this study, genomic DNA from 29 pairs of HCC and corresponding non-tumour tissues infected with hepatitis B virus (HBV) was prepared. Five CA-repeated microsatellite markers, including D8S277, D3S1029, D5S409, D2S123, and TP53, were used to analyse microsatellite alterations and their subtypes in these patients by polymerase chain reaction (PCR) amplification and denatured polyacrylamide gel electrophoresis. Microsatellite alterations were found in 15 of the 29 HCC patients (51.72%), implying that microsatellites are unstable in genomic DNA of HBV-infected HCC. It was found that frequency of microsatellite alterations in these HCC patients was not associated with patients' age, sex, status of tumour differentiation, and tumour size. Frequency of microsatellite alterations in HCC patients with cirrhosis tended to be less than that in patients without cirrhosis, but Fisher's exact test, 2-tailed, showed that this difference was not significant. Significantly more microsatellite alterations in serum alpha-fetoprotein (AFP)-positive cases were observed than those in serum AFP-negative ones, implying that the elevation of AFP in HBV-infected HCC may be associated with microsatellite stability.

Adult↗
PubMed2001

Long-term effects of olanzapine, risperidone, and quetiapine on dopamine receptor types in regions of rat brain: implications for antipsychotic drug treatment.

Changes in members of the dopamine (DA) D(1)-like (D(1), D(5)) and D(2)-like (D(2), D(3), D(4)) receptor families in rat forebrain regions were compared by quantitative in vitro receptor autoradiography after prolonged treatment (28 days) with the atypical antipsychotics olanzapine, risperidone, and quetiapine. Olanzapine and risperidone, but not quetiapine, significantly increased D(2) binding in medial prefrontal cortex (MPC; 67% and 34%), caudate-putamen (CPu; average 42%, 25%), nucleus accumbens (NAc; 37%, 28%), and hippocampus (HIP; 53%, 30%). Olanzapine and risperidone, but not quetiapine, produced even greater up-regulation of D(4) receptors in CPu (61%, 37%), NAc (65%, 32%), and HIP (61%, 37%). D(1)-like and D(3) receptors in all regions were unaltered by any treatment, suggesting their minimal role in mediating actions of these antipsychotics. The findings support the hypothesis that antipsychotic effects of olanzapine and risperidone are partly mediated by D(2) receptors in MPC, NAc, or HIP, and perhaps D(4) receptors in CPu, NAc, or HIP, but not in cerebral cortex. Selective up-regulation of D(2) receptors by olanzapine and risperidone in CPu may reflect their ability to induce some extrapyramidal effects. Inability of quetiapine to alter DA receptors suggests that nondopaminergic mechanisms contribute to its antipsychotic effects.

Animals↗
PubMed2001

Diverse macular dystrophy phenotype caused by a novel complex mutation in the ELOVL4 gene.

PURPOSE: A 5-bp deletion in ELOVL4, a photoreceptor-specific gene, has been associated with autosomal dominant (ad) macular dystrophy phenotypes in five related families, in which phenotypes range from Stargardt-like macular dystrophy (STGD3; Mendelian Inheritance in Man 600110) to pattern dystrophy. This has been the only mutation identified in ELOVL4 to date, which is associated with macular dystrophy phenotypes. In the current study, the potential involvement was investigated of an ELOVL4 gene variation in adSTGD-like and other macular dystrophy phenotypes segregating in a large unrelated pedigree from Utah (K4175). METHODS: The entire open reading frame of the ELOVL4 gene was analyzed by direct sequencing in a proband from the K4175 family. The combination of denaturing high-performance liquid chromatography (DHPLC) analysis and direct sequencing of all available family members was used to further assess segregation of identified ELOVL4 variants in the pedigree. RESULTS: A complex mutation, two 1-bp deletions separated by four nucleotides, was detected in all affected members of the family. The mutation results in a frameshift and the truncation of the ELOVL4 protein, similar to the effect of the previously described 5-bp deletion. CONCLUSIONS: The discovery of a second mutation in the ELOVL4 gene segregating with macular dystrophy phenotypes confirms the role of this gene in a subset of dominant macular dystrophies with a wide range of clinical expressions and suggests a role for modifying genes and/or environmental factors in the disease process.

Adolescent↗
PubMed2001

[The effect of tamoxifen of endometrium].

OBJECTIVE: To evaluate the effect of tamoxifen on the endometrium. METHODS: Hysteroscopy and endometrial biopsies were performed in 26 patients with breast cancer receiving tamoxifen and having vaginal bleeding or endometrial thickness detected by ultrasound. In addition 78 women with postmenopausal bleeding without receiving tamoxifen underwent the same examination. RESULTS: Thirteen (50.0%) patients receiving tamoxifen had endometrial or endocervical polyps, whereas 14 cases(17.9%) not receiving tamoxifen developed the polyps (P < 0.05). Nine (34.6%) patients receiving tamoxifen had thyperplasias, which was significantly higher than that of women not receiving tamoxifen (P < 0.05). CONCLUSIONS: The incidence of endometria disease in the patient with breast cancer receiving tamoxifen was increased. These patients should be closely monitored by transvaginal sonography and hysteroscopy.

Antineoplastic Agents, Hormonal↗
PubMed2001

[Applied anatomical study of blood supply in human palate].

OBJECTIVE: To investigate the origins and distributions of palatal vasculature and the three dimensional architecture. METHODS: Materials consisted of 14 normal and 10 cleft palate head-and-neck specimens. After vascular infusion, specimens were seprately analysed by stereomicroscopy, radiography, histological study and scanning electron microscopy. RESULTS: The greater palatine artery was the main vessel to supply the hard palate and the ascending palatine artery provided the principal supply of soft palate. The branches of greater palatine artery formed abundant anastomoses with the neighbor vessels. The ascending palatine artery divided into two branches in the soft palate. The artery branches in hard palate took on tree-like appearance and were arranged parallel. The capillary network was loosely packed. Whereas, the arteries in soft palate were always found to be crooked. The angles of the branches from the main trunk were changeable. The capillary network was packed densely. The vascular origins and courses of the cleft palate specimens were the same as the normal person, but the distributions and anastomoses were different. CONCLUSIONS: The blood supplies of hard and soft palate come from different vascular vessels and their vascular architectures have their own character.

Child, Preschool↗
PubMed2001

[Experimental study of motor nerve innervation of uvala muscle].

OBJECTIVE: To investigate the motor nerve innervation of uvala muscle. METHODS: Horseridish peroxidase (HRP) retrograde tracing technique was used in conjunction with selective intracranial severing of cranial nerve rootlets in 8 rabbies. RESULTS: Following HRP injection into uvala muscles, labeled motoneurons were located in the rostral section of nucleus ambiguus. No labeled motoneurons were found in the facial nucleus. Labled motoneurons were ipslaterally abolished after the cranial rootlets of accessory nerve on one side were intracranially severed. CONCLUSIONS: Uvala muscles are innervated by the motoneurons in the nucleus ambiguus. The axons of those motoneurons come out of the cranium through the cranial rootlet of the accessory nerve, then join the vagus, distributed via the pharyngeal branches of vagus.

Animals↗
PubMed2001

[Clinical investigation of burn wound infection with type I herpes simplex virus].

OBJECTIVE: To elucidate the clinical features of burn wound infection with type I herpes simplex virus (HSV -- 1), so as to propose the possible therapeutic measures. METHODS: Burn wound infection with HSV -- 1 was diagnosed in 7 cases by means of bacterial culture, PCR detection of virus, immunohistochemical staining and pathomorphological section with the exclusion of other causes. In addition, the clinical signs and the features of the development of the infection in 62 cases were recorded and analyzed. RESULTS: In the burn patients with the infection, the burn wounds were covered by tumor-like masses with the cauliflower appearance. In the 7 cases who underwent pathomorphological examination, 5 with positive HSV -- I. Epithelial cells exhibited balloon -- like appearance, and reticular degeneration, and inclusion bodies were found in balloon-like cells under microscope examination. In the late stage, there revealed obvious proliferation of epithelial prickle cell layer in shape of pseudopapillomatous mass with the obvious liquefaction of basal cells. The sufferers exhibited evident local signs with mild systemic reaction. The management of the wound included wet compress with the addition of neomycin and pentacyclic guanosine. CONCLUSION: With the employment of PCR virus detection and immunohistochemical staining, burn wound infection with HSV -- I could be identified. Non -- surgical treatment could be effective.

Adolescent↗
PubMed2001

[Enantiomeric separations of 1-1,2,4-triazole compounds by micro-high performance liquid chromatography].

The enantiomeric separations of sixteen novel 1-1,2,4-triazole chiral compounds were investigated by micro-HPLC with a 200 mm x 100 microns i.d. capillary chiral OD column. The detection was performed at 223 nm. The mobile phase was a mixture of iso-propyl alcohol and n-hexane(20:80, V/V) at a flow rate of 30 microL/min and column head pressure of 6.9 MPa. Some of the enantiomers could be separated on baseline. In comparing with the separation results by the conventional HPLC method, the micro-HPLC method had the advantages of high-speed, economy, environmental friendliness etc. The effect of solute structure on enantio-selectivity was investigated and the chiral recognition mechanism was also discussed. It was found that the main separation mechanisms involve the pi-pi association and inclusion between the substituent R and the spiral pocket of OD-CSP.

2-Propanol↗
PubMed2001

[Expression of two truncated enhancin gene from Helicoverpa armigera granulosis virus in E. coli and its preliminary bioassay].

The plasmids pET-30a-Ben and pET-30a-Den which included 1.7 kd and 2.2 kb fragments of 5'-terminal of HaGV enhancin gene were obtained by cutting recombinant plasmid pET-30a-En with Bal I and Dra I respectively. Two fragments were expressed in E. coli successfully and the products were named Ben and Den respectively. The enhancement, which Ben and Den enhance the infectivity of HaNPV and Bt in 3rd larvae of Helicoverpa armigera, was studied. The results indicated that there was increase of the mortality of 10.5%-26.5% and the LT50 decrease of 0.9 d causes by adding Ben, while Den could increase the mortality by 10.2%-33.0% and decrease the LT50 by 1.2 d-1.9 d. The preliminary bioassay on Bt against Helicoverpa armigera indicated the recombinant enhancin could increase the mortality of larvae by 20.7%-35.4%, Den by 16.7%-31.5%, Ben by 11.7%-27.4%.

Animals↗
PubMed2001

[Application of differential wavelet in detecting QRS complexes of ECG signal].

An algorithm based on wavelet transforms (WT'S) has been developed for detecting QRS complexes of ECG signal. In this paper, we use Mallat algorithm to calculate dyadic Marr wavelet transforms, analyse the relationship between singularity of the signal (the peak of R wave) and local maximal value of WT's from the view of equivalent wavelet filter, discuss the performance distinction between quadratic differential wavelet and single differential wavelet for singularity detection. Some other tactics are also applied to improve the anti-interference performance of the algorithm and to increase the correct detection rate of QRS complexes. Verified by the MIT-BIH Arrhythmia Database, the correct detection rate of QRS complexes is 99.8%.

Algorithms↗
PubMed2001

[Determination of phospholipid in Cibotium barometz by supercritical fluid extraction and RP-HPLC].

A supercritical fluid extraction (SFE) method was used to extract phospholipids in Cibotium barometz. After a homogeneous design experiment, SFE conditions were obtained which were pressure at 31.5 MPa, temperature at 46.2 degrees C and a 0.37 L/kg modifier in supercritical fluid. The sample was extracted for 2 hours. A RP-HPLC method was developed for the determination of phosphatidylcholine. RP-HPLC conditions included a RP-HPLC column packed with Waters Symmetry C18(5 microns), a mobile phase composed of methanol-1% phoshporic acid(90:10) and the detection wavelength at 206 nm. The content of phosphatidylcholine was 0.198%(RSD 4.2%), and the method can be a measure of quality control for Cibotium barometz and its preparations.

Chromatography, High Pressure Liquid↗
PubMed2001

[Spectrophotometric study on the interaction of protein with acid dye].

Spectrophotometric characters of protein interaction with chromazurol S(CAS), bromocresol green (BCG), bromopyrogallol red (BPR) and methylthymol blue (MTB) have been studied in acid and alkaline medium respectively. Protein can combine the above mentioned dye to reduce absorptivity of dye solution of CAS and BCG at pH 3.8 and pH 4.0, to add absorptivity of dye solution of BPR and MTB at pH 3.8 and pH 10.8 for the bathochromic shift of wave length of maximal absorption of them to add 10 nm and 20 nm respectively. The linear relationship holds between the reduced or added absorptivity of dye and the optimum concentration range of protein. The interaction mechanism of protein and dye has been discussed tentatively.

Acids↗
PubMed2001

[Clinical diagnosis and treatment of acquired immunodeficiency syndrome complicated by tuberculosis].

OBJECTIVE: To explore the clinical characteristics and method of therapy of acquired immunodeficiency syndrome (AIDS) patients complicated by tuberculosis. METHOD: 10 cases suffered from AIDS complicated by tuberculosis from 1995 to 2000 were analyzed. RESULTS: (1) Clinical type: of the 10 cases, hematogenous disseminated tuberculosis with cerebral tuberculosis in 3, tuberculous lymphadenitis in 4 (in which one was in mesentery, one in mediastinum and neck, 2 in neck), primary pulmonary tuberculosis in 3, with other opportunistic infections, such as Pneumocystis carinii pneumonia (PCP). (2) Immunological and tuberculin test: in all 10 cases, CD4+ cells were (2 - 87) x 10(6)/L, of them 7 cases CD4+ cells less than 50 x 10(6)/L, mean CD4+ (33 +/- 13) x 10(6)/L. Tuberculin tests were negative. (3) TREATMENT: 5 cases were treated with anti-tuberculosis and highly active anti-retrovirus treatment (HAART), the others were treated with anti-tuberculosis only. Six months later, comparing with anti-tuberculosis, CD4+ cells in patients of anti-tuberculosis with HAART increased significantly (P < 0.05, respectively). CONCLUSIONS: The decrease of CD4+ cell might be important in AIDS with tuberculosis. Tuberculin test is not a good way of diagnosing AIDS with tuberculosis. Among AIDS complicated by tuberculosis, hematogenous disseminated tuberculosis and extra-pulmonary tuberculosis are common and usually combined with other various opportunistic infections, clinical manifestations are complex and treatment should be prolonged. This combined treatment can shorten treating time and improve the prognosis of AIDS with tuberculosis.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Teleconvection: remotely driven thermal convection in rotating stratified spherical layers.

We report the discovery of a convective phenomenon found to occur in a rotating spherical system in which an inner convectively unstable fluid layer is bounded by a corotating outer convectively stable fluid layer. Although convection is thermally driven in the unstable interior, the resulting convective motions concentrate primarily in the stable outer region. This phenomenon, which we term teleconvection, suggests that fluid motions observed at the "surface" of a planet (such as Jupiter's alternating zonal winds) may be driven by an energy source located deep inside the planet.

Journal Article↗