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Biomedical subjects

W Zhang

Publications and source records attributed to W Zhang.

At least 847 records · Page 47Linked to original sources
PubMed1998

[Comparative molecular field analysis(CoMFA) of allylamine and benzylamine antimycotics].

"Active analog approach" has been employed to search the pharmacophoric conformation of the allylamine and benzylamine antimycotics. A local minimum energy conformation, which is very similar to the crystallographically determined coordinate of naftifine or terbinafine, has been applied to build all compounds. Comparative molecular field analysis (CoMFA) has been used to examine the correlations between the activities against 6 common human pathogenic fungi and the physicochemical properties of 62 allylamine and benzylamine compounds which had been aligned by rms fit rule. The predictive abilities of the resulting 3D-QSAR models have been tested by 8 new synthetic compounds and 5 reported compounds. Finally, we propose an interaction pattern between allylamine, benzylamine antimycotics and the active site of pseudoreceptor based on the results of 2D-QSAR and 3D-QSAR.

Allylamine↗
PubMed1998

[Studies on urinary metabolites of HH07A, a derivative of hainanensine, in rats].

The metabolism of HH07A in the rat has been investigated by GC-MS. After oral administration of HH07A, the rat urine was passed through a macroporous XAD-2 resin column and eluted with methanol. The methanol extract was hydrolyzed with glucuronidase, extracted with dichloromethane and concentrated for TMS derivatization with GC-MS. The mass spectra of HH07A and its four metabolites as well as their derivatives were presented. The structures of the metabolites were proposed and the in vivo metabolic pathway of HH07A was given in Figure 6.

Animals↗
PubMed1998

[Receptor-mediated endocytosis induced macrophage cytosolic acidification and exocytosis].

The effects of Con A, WGA, Zymosan A on macrophage cytosolic pH and outflow of lysosomal content through exocytosis were studied with SNAFL-calcein and FITC-Dextran on ACAS570. The results showed all three ligands could induce macrophage cytosolic acidification in about 10 min and kept at the same level hereafter; outflow of lysosomal fluorescent probe through exocytosis appeared in 15-20 min. In resting conditions, macrophage lysosomes mainly distributed in cell center; after stimulated for 15 min by three ligands, the number of lysosomes increased in membrane periphery, in 25-30 min lysosomes moved back toward cell center. We proposed that ligands induced lysosomal pH rises was a basic factor for outflow of lysosomal content through exocytosis, cytosolic acidification inhibited receptor-mediated endocytosis. Cytosolic acidification and outflow of lysosomal content through exocytosis were the results of cellular self-regulation and self-protection during receptor-mediated endocytosis.

Animals↗
PubMed1998

[Effects of l-stepholidine on the peripheral vascular dopamine DA1 and DA2 receptor subtypes].

The effects of l-stepholidine(l-SPD) on peripheral vascular dopamine DA1 and DA2 receptors were studied using isolated vascular rings in rabbits. It was shown that (1) l-SPD(0.1-10 mumol.L-1) shifted the dose-response curves to the right in a nonparallel fashion and decreased the maximal response (Emax) of both the fenoldopam(FODA, a selective DA1 agonist)-induced and the propyl-buty-dopamine(PBDA, a selective DA2 agonist)-induced vasorelaxation showing a non-competitive antagonistic action. The pD2 values of l-SPD for FODA in the renal, pulmonary and mesenteric arteries were 5.43, 5.48 and 5.58, respectively. The pD2 values for PBDA in the mesenteric and femoral arteries were 5.35 and 5.89, respectively. The potencies of its antagonistic action were comparable to SCH23390, a selective DA1 antagonist, and to domperidone, a selective DA2 antagonist. (2) l-SPD(0.1-100 mumol.L-1) per se was also found to induce slight but dose-related vasorelaxations in the renal and pulmonary arteries displaying its DA1 agonistic activity. Its pD2 values were 4.98 and 5.02, respectively. However, its Emax were considerably smaller than that of FODA. These results suggest that l-SPD is a mixed peripheral DA1 and DA2 receptor antagonists and weak DA1 receptor agonist with pharmacological property of dual action.

Animals↗
PubMed1998

[Clinicopathological analysis of 15 cases of desmoplastic ameloblastoma].

15 cases of desmoplastic ameloblastoma (DA) were studied clinicopathologically, which was combined with literature review of 50 cases. The results showed that the morbidity of DA was low, which occupied 7.4% of the whole ameloblastoma. The DA tumor occurred preferentially in anterior parts of the jaw and the maxillary bone, which exhibited radiographically a mixed radiolucent-radiopaque appearance, and the main pathological characteristic was extensive fibrous hyperplasia in stroma and scattering epithelial nests with different sizes. Some cases showed a mixture type of DA and classical ameloblastoma.

Adult↗
PubMed1998

[Isolation and characterization of a insecticidal protein from Pseudomonas pseudoalcaligenes].

A insecticidal protein was purified by gel-filtration chromatography on Sephadex G-100 and anion-exchange chromatography on DEAE-Sephadex A-50 from the suspension of Pseudomonas pseudoalcaligenes culture. Certain biophysical and biochemical properties were also studied. The molecular weight of the subunit of the insecticidal protein is 25,100 and pI is 5.16. Amino acid composition analysis showed that it is an acidic protein.

Amino Acids↗
PubMed1998

[Pharmacognostical study of Chinese drug ningxia beimu].

This paper deals with the macroscopic, microscopic and chemical characteristics of the bulbs of Fritillaria taipaiensis var. ningxiaensis. This crude drug could be distinguished by shape, size, hilum and striations of the sample grains.

Alkaloids↗
PubMed1998

[Determination of Ni and Pd in white karat gold jewellery by the EDXRF extrapolate-regression method].

The EDXRF extrapolate-regression method described in this paper combines regression method with the fundamental formula of fluorescence intensity. The contents of Ni and Pd in white karat gold jewellery were calculated theoretically according to the spectrum of the sample. The content of gold was deternined without standards. The precision was 0.1% and the deviation was 0.3% compared with AA.

English Abstract↗
PubMed1998

Mechanism of nicotine-induced relaxation in the porcine basilar artery.

The present experiment was designed to examine possible influence of adrenergic nerves on nicotine-induced neurogenic vasodilation in porcine basilar arteries denuded of endothelium. Nicotine and transmural nerve stimulation (TNS) induced relaxation of basilar arteries. Tetrodotoxin (TTX) abolished the relaxation elicited by TNS, but only partially blocked that induced by nicotine. Relaxation induced by both nicotine and TNS was abolished by N-nitro-L-arginine. The N-nitro-L-arginine inhibition of both TNS- and nicotine-induced relaxation was reversed by L-arginine but not by D-arginine. Hexamethonium abolished the relaxation induced by nicotine, but did not affect that elicited by TNS. Relaxation induced by nicotine was diminished by guanethidine, which did not affect the relaxation induced by TNS, suggesting that guanethidine blockade of nicotine-induced relaxation is not due to its local anesthetic effect. Results from histochemical studies indicated that catecholamine fluorescence and NADPH-diaphorase fibers were not appreciably affected by guanethidine. Following incubation with 6-hydroxydopamine for 1 hr, the catecholamine fluorescence fibers in the basilar arteries completely disappeared, although the NADPH-diaphorase fibers were not affected. In these adrenergically denervated arteries, nicotine-induced relaxation was abolished, while the TNS-elicited relaxation was not affected. Furthermore, norepinephrine-induced relaxation in basilar arteries was blocked by N-nitro-L-arginine, but was not affected by N-nitro-D-arginine or hexamethonium. These results suggest that in porcine cerebral arteries nicotine-induced nitric oxide-mediated relaxation is dependent on an intact adrenergic innervation. Nicotine appears to act on nicotinic receptors on the presynaptic adrenergic nerve terminals to release norepinephrine or a related substance, which then stimulates release of nitric oxide from the neighboring nitric oxidergic nerves. The TNS-elicited nitric oxide-mediated relaxation, however, is resulted from direct depolarization of nitric oxidergic nerves.

Animals↗
PubMed1998

Loss of p21WAF1/Cip1 protein expression accompanies progression of sporadic colorectal neoplasms but not hereditary nonpolyposis colorectal cancers.

p21 (p21WAF1/Cip1), a cyclin-dependent kinase inhibitor, induces G1 arrest and can inhibit the activity of the proliferating cell nuclear antigen (PCNA). We analyzed p21 expression during colorectal tumorigenesis, its association with its transcriptional regulator p53, and its relationship to rates of cell proliferation and apoptosis. p21 and p53 protein expression were examined in sporadic tumors and hereditary nonpolyposis colorectal cancers (HNPCCs) by immunohistochemistry (IHC) and immunoblotting. Apoptosis was examined using a DNA nick end-labeling assay, and cell proliferation was examined by PCNA staining. In normal colorectal epithelia, nuclear p21 staining was uniformly detected in crypt cells of the superficial compartment (upper one-third) that stained negatively for PCNA. p21 and PCNA expression were, therefore, mutually exclusive. In sporadic cases, a decrease in the frequency of p21 expression accompanied adenoma development and progression to carcinoma. Specifically, p21 was detected in 12 of 16 (75%) adenomas and 10 of 32 (31%) carcinomas. In contrast to sporadic cases, HNPCCs with known mutations in DNA mismatch repair genes expressed p21 in 12 of 15 (80%) carcinomas. An inverse relationship between p21 and p53 was observed wherein mutant p53 proteins were detected in 4 of 15 (27%) HNPCCs versus 22 of 32 (69%) sporadic carcinomas. Although p21+ carcinoma cells were generally negative for p53, IHC revealed that some carcinoma cells expressed both p21 and p53 proteins. Furthermore, p53-mutated SW480 colon carcinoma cells were found to coexpress p21 and p53, suggesting that p21 can also be activated by a p53-independent mechanism. No association was found between p21 or PCNA and apoptotic labeling indices in adenomas or carcinomas. In conclusion, a decrease in p21 expression accompanies neoplastic progression in sporadic cases but not in HNPCCs. This finding appears related to p53 status in that the frequency of p53 expression was significantly reduced in HNPCCs compared to sporadic cases, suggesting a difference in their molecular pathways of tumorigenesis.

Colorectal Neoplasms↗
PubMed1998

Characterization of phospholipids in pre-alpha HDL: selective phospholipid efflux with apolipoprotein A-I.

Previously, we have shown that lipid-free apoA-I, when incubated with fibroblasts, will produce lipoproteins of pre-alpha mobility (Asztalos, B. F., et al. 1997. Arterioscler. Thromb. Vasc. Biol. 17: 1630-1636). In order to understand the nature of these pre-alpha particles, we further characterized their lipid content. The pre-alpha particles are high density lipoproteins, having a median density of 1.08 g/ml. They have a surface charge of -18.45 mV. The phospholipid composition of these particles showed that they have 4% each of phosphatidyl ethanolamine and inositol; 69% phosphatidyl choline and 18% sphingomyelin. This phospholipid composition is different from those of plasma HDL (81% phosphatidyl choline, 13% sphingomyelin), plasma membrane on the fibroblasts, and whole fibroblast phospholipid. To demonstrate that the pre-alpha mobility resides in the lipids, lipids from pre-alpha lipoproteins were reconstituted with lipid-free apoA-I. The resultant particles retained their pre-alpha mobility. We conclude that apoA-I may react with specific regions of plasma membrane to acquire this unusual lipid composition and that pre-alpha mobility is caused in part by the unusual phospholipid composition.

Apolipoprotein A-I↗
PubMed1998

Presence of antibodies to human papillomavirus virus-like particles (VLPs) in 11-13-year-old schoolgirls.

To allow meaningful approaches to vaccine development, it is important to know the extent of exposure to human papillomavirus (HPV) within the general population, and particularly the age at which the at risk population is infected. The humoral response to human papillomavirus is directed largely to conformationally-dependent epitopes on the whole virion. Virus-like particles (VLPs) of HPV types 1, 2, and 16 were produced using a baculovirus expression system, and were used in the intact state as antigen in an indirect ELISA. Anonymised serum samples from a cohort of Edinburgh schoolgirls were tested for the presence of IgG antibodies directed against the VLPs. The reproducibility of the ELISA was assured by repeated testing of control samples, and by testing all samples in duplicate and, where possible, on several occasions. Of 1,192 tested with the HPV16 VLPs, 90 (7.6%) were classified as clearly positive, and a further 87 (7.3%) were positive but close to the cutoff calculated by comparison with a group of consistently negative sera. Antibodies to HPV2 were detected in 37.5% (407/1,139) and antibodies to HPV 1 in 51.9% (558/1,076) of the schoolgirls. Antibodies to both HPV1 and HPV2 were found frequently, being present in 29.7% (295/ 993) of samples tested; 40 samples had antibodies to all three types. The significance of these results is discussed.

Adolescent↗
PubMed1998

Profiling of differentially expressed genes in human primary cervical cancer by complementary DNA expression array.

The profiling of differentially expressed genes from primary tumor samples using cDNA expression array can reveal new tumor markers as well as target genes for therapeutic intervention. Using cDNA expression array technology, we produced an expression profile of genes that are associated with human cervical cancer. Hybridization of the cDNA blotting membrane (588 genes on a single membrane) was performed with 32P-labeled cDNA probes synthesized from RNA isolated from either normal cervix or cervical cancer. Parallel analyses of the hybridized signals enabled us to profile genes that were differentially expressed in cervical cancer. In each experiment, the extent of hybridization of each gene was evaluated by comparison with the most abundant mRNAs in the human cervix. These include myc proto-oncogene, 40S ribosomal protein S19, heat shock proteins, leukosialin S (CD43), integrin alphaL (CD11A), calgranulin (A), and CDK4 inhibitor (p16ink4). No detectable changes were observed in the expression levels of these genes. Several mRNAs, such as those encoding guanine nucleotide-binding protein Gs (alpha subunit), leukocyte adhesion protein (LFA1-beta), nuclear factor NF45, homeobox protein Hox-A1, and beta-catenin were detected in increased levels in cervical cancer. Genes that showed decreased expression in cervical cancer tissue were a group of apoptosis-related proteins, cell adhesion molecules, nuclear transcription factors, and a homeobox protein (Hox7). For example, the expression levels of Smad1 and Hox7 were consistently decreased in all tumor tissues tested. Northern analysis of Smad1 and Hox7 RNA in primary cervical tumor tissues and cervical carcinoma cell lines indicated that, in general, the mRNA levels of these genes were decreased in human cervical cancer. The precise relationship between the altered expression of these genes and cervical tumorigenesis is a matter of further investigation.

DNA, Complementary↗