Biomedical subjects

Z Pan

Publications and source records attributed to Z Pan.

At least 109 records · Page 6Linked to original sources

PubMed1997

[Study on the direct determination of Pb and Cd in milk powder by GFAAS].

The paper reports the direct determination of Pb and Cd in milk powder by GFAAS. The mothed does not need any pre-treatment to the samples and fully use some function of pre-treatment which the Graphite Furnace have. The result indicates that the method is simple, rapid and accurate, and the false result from any pre-treatment to the samples can be reduced. The recover rate of Pb is 100.1%, CV =2.7 ; and Cd is 98.6%, CV = 3.1 %. This method is also applied to the rapid determination of Pb and Cd in soluble samples with satisfactory results.

Analytic Sample Preparation Methods↗

PubMed1997

Epidemiological survey on clonorchiasis sinensis in Yangxin County of Hubei Province of PR China.

An epidemiological survey of clonorchiasis was conducted at Panqiao township of Yangxin County of Hubei Province from June to November, 1993. The positive rate of cercaria in the body of intermediate hosts, Parafossarulus stratulus and Alocinma longicornis was 12.25% and 3.84% respectively. Positive rates of metacercariae in the bodies of Pseudonaphona parva was 48.15%, Ctenopharyngodon idellus 17.24% and Hypophthalmichthys nobilis 18.18%. Positive rate of eggs in the feces of cats was 36.36% and pigs 16.67%. It has been confirmed that there is a natural focus of clonorchiasis sinensis at Yangxin County of Hubei Province. A total population of 6,865 in 20 sites of 10 production brigades of Panqiao township was surveyed for infection with Clonorchis sinensis. The average infection rate in the local residents was 5.80%. Male had a higher infection rate than female. The infected persons were mainly peasants and school girls and boys. Most of the infected persons had light infections (I0) without a serious clinical manifestations.

Adolescent↗

PubMed1997

A phase I trial of paclitaxel plus carboplatin in untreated patients with advanced non-small cell lung cancer.

This Phase I study was designed to determine the maximally tolerated doses of paclitaxel (given as an outpatient 3-h infusion) plus carboplatin in advanced, untreated non-small cell lung cancer. Secondary objectives were to determine the response rate, response duration, and survival. Fifty-six patients were accrued, and all were evaluable for toxicity; 50 patients were assessable for response. Paclitaxel doses ranged from 135-250 mg/m2, whereas carboplatin dosing started at 250 mg/m2 and was escalated to 400 mg/m2. Patients received therapy on day 1 every 21 days for a maximum of six cycles. Prophylactic granulocyte colony-stimulating factor was not given initially but was allowed if grade 4 neutropenia developed. Neutropenia was the major toxicity observed (41% of patients; 16% of courses) and was dose related. However, febrile neutropenia was uncommon (4%), and no patient receiving growth factor developed subsequent grade 4 neutropenia. Only one patient developed grade 4 thrombocytopenia. No grade 4 neuropathy or grade 3 or 4 myalgias/arthralgias were reported. Grade 4 allergic reactions occurred in three patients (5%), and two patients sustained grade 4 cardiac toxicity (4%). Partial responses were observed in 13 of 50 patients (26%). One of 13 patients (8%) receiving paclitaxel at 135 mg/m2 and carboplatin (250-350 mg/m2) responded versus 12 of 37 patients (32%) receiving paclitaxel doses >/= 175 mg/m2 with carboplatin doses of 350-400 mg/m2. The median time to progression, median survival, and 1-year survival rates seemed to be dose related, with median times to progression of 6, 18, and 27 weeks; median survival of 13, 29, and 39 weeks; and 1-year survival rates of 15, 28, and 41% for the 135, 175-200, and 225-250 mg/m2 groups. We conclude that full doses of both paclitaxel and carboplatin can be given safely on an outpatient basis with 3-h paclitaxel infusions. Neutropenia is the most common toxicity; response rates and survival at higher dose levels were encouraging. Phase III trials to determine the optimal dose and infusion schedule of this combination are warranted, as are trials to compare paclitaxel/carboplatin to other active single agents or combination regimens.

Adult↗

PubMed1997

[The effect of repair of paratendon in tendon healing].

In order to investigate the effect of repair of paratendon in tendon healing, two different ways were performed to repair the transected extensor tendons of chick's toe. End to end suture of the extensor tenon was performed in group 1 while the paratendon was also repaired simultaneously in addition to suture of the tendon in group 2. Gross observation and histological examination were undertaken in the 3rd and 6th week after operation. The result showed, in group 1, extensive adhesion and irregular proliferation of fibroblasts was found in the 3rd week, severe adhesion and irregular arrangement of fibroblasts with less collagen fiber was found in the 6th week; while in group 2, smooth and regular "fusiform structure" was formed, slight adhesion and regular proliferation of fibroblasts were found in the 3rd week, adhesion disappeared and the structure of paratendon and tondon recovered in the 6th week. It was concluded that repair of extensor tendon and paratendon simultaneously could promote the intrinsic tendon healing and prevent tendon adhesion.

Animals↗

PubMed1996

Increased uptake of L-cysteine and L-cystine by nerve growth factor in rat pheochromocytoma cells.

Nerve growth factor is a neurotrophic factor which promotes cell survival and differentiation in the central and peripheral nervous system. The rat pheochromocytoma (PC12) cell has been frequently used to study the actions of nerve growth factor (NGF). Our previous studies demonstrate that pretreatment with NGF for 24 h protects PC12 cells from oxidative stress by increasing glutathione (GSH) concentrations and the activity of gamma-glutamylcysteine synthetase, which is a rate-limiting enzyme in GSH synthesis. The synthesis of intracellular GSH is dependent on the availability of the precursor amino acid, L-cysteine. Cells take up L-cystine from the extracellular fluid and convert it to L-cysteine intracellularly. L-Cysteine is then released from cells to maintain extracellular L-cysteine. Here we report that NGF increased the uptake of L-cysteine or L-cystine. The increased concentrations of L-cysteine or L-cystine by NGF was responsible for the enhanced intracellular GSH concentrations. The increased GSH and L-cysteine concentrations by NGF also served as intracellular antioxidants. The protection of PC12 cells by NGF from oxidative stress was due to the stimulated increased levels of intracellular glutathione and L-cysteine or L-cystine.

Animals↗

PubMed1996

Cloning, characterization, and heterologous expression of cDNAs for farnesyl diphosphate synthase from the guayule rubber plant reveals that this prenyltransferase occurs in rubber particles.

Two farnesyl diphosphate synthase (FPS) cDNA's from a guayule stembark library were isolated and characterized. Both encode M(r) 39,000 proteins containing 432 amino acids that differ slightly in their deduced molecular weights and isoelectric points. They both contain the DDXXD motifs that are characteristic of prenyltransferases, and both isoforms show high homology to other plant FPS sequences but less overall homology to FPS sequences from nonplant sources. The two isoforms differ by 5% in their amino acid sequence. When expressed in Escherichia coli, each guayule isoform exhibits high specific activity that produces farnesyl diphosphate as the major isoprenoid and small amounts of geranyl diphosphate. Biochemical and immunological evidence also indicates that FPS is associated with guayule rubber particles. Antibodies to chicken FPS cross-react with both guayule isoforms expressed in E. coli and recognize a low abundance M(r) 39,000 protein in rubber particles purified from guayule stembark. Guayule FPS sequences show high homology to peptide fragments of the prenyltransferase associated with rubber particles from Hevea brasiliensis, suggesting that this enzyme may be important for rubber biosynthesis in both species.

Alkyl and Aryl Transferases↗

PubMed1996

cDNA cloning of a novel G protein-coupled receptor with a large extracellular loop structure.

A cDNA designated as AZ3B has been isolated from a differentiated HL-6 0 cell cDNA library with a probe derived from the N-formyl peptide receptor gene. The 1.97-kb cDNA encodes a novel G protein-coupled receptor (GPCR) with 482 amino acids. In addition to the predicted 7 transmembrane domains common to all GPCRs, the protein encoded by AZ3B contains a large extracellular loop of approximately 172 amino acids between the fourth and the fifth transmembrane domains, a feature unique among the hundreds of GPCRs identified to date. High sequence homology exists between the AZ3B protein and a number of chemoattractant receptors in the amino-terminal 170 residues and the carboxyl-terminal 150 residues. Northern and flow cytometric analyses suggested that the AZ3B message and protein are widely expressed in several differentiated hematopoietic cell lines, in the lung, placenta, heart, and endothelial cells. We postulate that the AZ3B protein defines a distinct group of receptors within the GPCR superfamily.

Amino Acid Sequence↗

PubMed1996

Correlation of tumor markers p53, bcl-2, CD34, CD44H, CD44v6, and Ki-67 with survival and metastasis in laryngeal squamous cell carcinoma.

BACKGROUND: Recent basic discoveries about the biological significance of nuclear and cell-surface marker proteins have opened new areas of research into head and neck cancer. However, the clinical significance of these markers is not yet understood. OBJECTIVE: To perform a historical prospective study of 70 patients with squamous cell carcinoma of the larynx who were treated at our institution between 1979 and 1989 to correlate tumor marker expression with survival and metastasis. DESIGN: Archival tissue was immunohistochemically stained for the p53 tumor suppressor gene product, the inhibitor of apoptosis (bcl-2), the stem cell marker CD34, the cell adhesion molecules CD44H and CD44v6, and a marker of cellular proliferation (Ki-67). The slides were examined using a light microscope and scored according to intensity and percentage of cells labeled. The patients were stratified by tumor stage, and survival and metastatic data were correlated with staining scores. RESULTS: For the stage IV group, increased expression of p53 and decreased expression of CD44H and CD44v6 correlated with a decreased survival (P = .03, P = .03, and P = .02, respectively), and decreased expression of CD44H correlated with an increase in metastasis (P = .01). For all stages, excluding metastatic cases, increased p53 expression was consistent with a shorter survival (P < .03), while increased CD44v6 expression was consistent with a longer survival (P < .02). CONCLUSIONS: The present study suggests that a loss of cell proliferation control implied by overexpression of p53 and loss of cell adhesion implied by decreased expression of CD44 may be determinants of survival in patients with carcinoma of the larynx. The tumor markers bcl-2 and Ki-67 were not prognostic discriminators in this limited series. This study also indicates that the stem cell marker CD34 is rarely expressed by laryngeal carcinoma cells.

Adult↗

PubMed1996

Stimulation of NF-kappa B activation and gene expression by platelet-activating factor.

PAF stimulation of NF-kappa B activation and transcription of immediate-early genes have been investigated in peripheral blood mononuclear cells and in transfected Chinese hamster ovary cells expressing the cloned PAF receptor. These studies identified a G protein-coupled pathway for PAF induction of gene expression and transcription factor activation, which differs from the mechanisms employed by other immediate-early gene inducers. Potential significance of PAF induced NF-kappa B activation is discussed.

Animals↗

PubMed1996

Progesterone receptor-induced bending of its target DNA: distinct effects of the A and B receptor forms.

We have used circular permutation and phasing electrophoretic mobility shift assays to determine the ability of the A and B forms of human progesterone receptor (PR) to bend target DNA. Studies were done with baculovirus-expressed full-length receptors purified to apparent homogeneity. By circular permutation analysis, both forms of PR induced substantial distortions in the structure of target DNA with calculated distortion angles (alpha D) of 57 degrees for PR-A and 84 degrees for PR-B. The apparent bend centers for both forms of PR were similarly located a few base pairs (-4 to -2 bp) from the middle of the progesterone response element. No differences were detected in the magnitude of distortion or apparent bend centers when PR was bound to hormone agonist (R5020) or the antagonist RU486. Phasing analysis, which can determine the orientation of a DNA bend, revealed that both forms of PR mediated directional bends toward the major groove of the DNA helix. Calculated directed bend angles (alpha B) were 40 degrees for PR-B and 31 degrees for PR-A. The chromatin high mobility group protein HMG-1, which acts as an accessory factor to enhance the binding affinity of purified PR for progesterone response elements, had minimal influence on PR-mediated DNA bending. This result, taken together with the fact that HMG-1 can form a ternary complex with PR and DNA, is consistent with the conclusion that HMG-1 facilitates PR binding by stabilizing a receptor-induced DNA conformation that is required for assembly of a high affinity PR-DNA complex. The results of this study also suggest that DNA bending may be coupled to transcriptional regulation since PR-B is generally a stronger transcriptional activator than PR-A and also mediates a larger bend in target DNA than PR-A.

Animals↗

PubMed1996

Gene transcription through activation of G-protein-coupled chemoattractant receptors.

Receptors for leukocyte chemoattractants, including chemokines, are traditionally considered to be responsible for the activation of special leukocyte functions such as chemotaxis, degranulation, and the release of superoxide anions. Recently, these G-protein-coupled serpentine receptors have been found to transduce signals leading to gene transcription and translation in leukocytes. Transcription factors, such as NF kappa B and AP-1, are activated upon stimulation of the cells with several chemoattractants at physiologically relevant concentrations. Activation of transcription factors through these receptors involves G-protein coupling and the activation of protein kinases. The underlying signaling pathways appear to be different from those utilized by TNF-alpha, a better characterized cytokine that induces the transcription of immediate-early genes. Chemoattractants stimulate the expression of several inflammatory cytokines and chemokines, which in turn may activate their respective receptors and initiate an autocrine regulatory mechanism for persistent cytokine and chemokine gene expression.

Animals↗

PubMed1996

Role of calmodulin in HIV-potentiated Fas-mediated apoptosis.

The recently demonstrated extraordinary rate of turnover of T cells in human immunodeficiency virus (HIV)-1-infected patients and the apparently concomitant high rate of viral production and death are consistent with a large amount of cell death directly due to infection. Apoptosis may be one of the major forms of T cell death in HIV-1 infection. Many apoptotic pathways depend on calcium and therefore would be expected to involve calmodulin. As the HIV-1 envelope glycoprotein, gp160, contains two known calmodulin-binding domains, we investigated the possibility that the cytoplasmic domain of the HIV-1 envelope protein gp160 could enhance Fas-mediated apoptosis, the major form of apoptosis in lymphocytes. Our studies have shown that 1) transfection of H9 and MOLT-4 cells with a non-infectious HIV proviral clone, pFN, which expresses wild-type gp160, leads to enhanced Fas-mediated apoptosis, 2) transfection of MOLT-4 cells with a pFN construct pFN delta 147, which expresses a carboxyl-terminally truncated gp160 lacking the calmodulin-binding domains, produces less Fas-mediated apoptosis than transfection with pFN, and 3) the calmodulin antagonists trifluoperazine and tamoxifen completely inhibit the pFN enhancement of Fas-mediated apoptosis in MOLT-4 cells. We have replicated all of these results using the vectors pSRHS and pSRHS delta 147, which express wild-type gp160 and truncated gp160, respectively, in the absence of other viral proteins. These investigations provide a mechanism by which HIV-1 may induce apoptosis and a possible intracellular target for future therapeutics.

Amino Acid Sequence↗

PubMed1996

Regulation of gamma-glutamylcysteine synthetase activity by nerve growth factor.

Nerve growth factor is a neurotrophic factor that regulates neuronal cell development, maintenance, and injury responses in the peripheral and central nervous system. Nerve growth factor reduces injury owing to oxidative stress in rat pheochromocytoma (PC12) cells by increasing intracellular glutathione, in part owing to its stimulation of the activity of gamma-glutamylcysteine synthetase, which is the rate-limiting enzyme in the synthesis of glutathione. Here we show that nerve growth factor did not increase the activity of gamma-glutamylcysteine synthetase in PC12 cells at the transcriptional level. Rather, nerve growth factor enhanced the stability of gamma-glutamylcysteine synthetase mRNA in PC12 cells. These results suggest that, during oxidative stress, nerve growth factor extended the half-life of gamma-glutamylcysteine synthetase mRNA, thus increasing gamma-glutamylcysteine synthetase mRNA levels compared to nerve growth factor-deprived PC12 cells.

Animals↗

PubMed1996

[Serodiagnosis of Helicobacter pylori infections by detection of immunoglobulin G antibodies with an immunoblot technique].

Serological testing has recently been proposed as an aid in diagnosis of H. pylori infections. In this study, an immunoblot method has been evaluated to diagnose H. pylori infection serologically by comparing 104 serum specimens from patients with a positive Gram stain and/or culture result and a positive urease test on biopsy material, as well as 30 serum specimens from patients with negative urease test, and negative microscopy and culture results. Thirteen bands could be identified by immunoblotting and were found significantly more frequent in patients with H. pylori infections than in patients without such infections. A semiquantitative grading system was introduced with score 1 for each reactive band and score 1/2 for a weakly reactive band. If score 2 was the cut-off value for IgG antibody, then the sensitivity, specificity, positive predictive value and negative predictive value of the immunoblot test were 100.0%, 90.0%, 97.2% and 100.0% respectively. There was no marked cross reaction with both Campylobacter jejuni and Campylobacter coli.

Adult↗

PubMed1996

[Influence of cerebral traumatic dementia treated with acupuncture at houxi and shenmen].

Sixty-two cerebral traumatic dementia patients were randomly divided into two groups acupuncture treatment group (Group A, 32 cases) and physical treatment group (Group B, 30 cases). The changes of MMSE scores and auditory P300 were observed before and after the treatment. It were found that the indexes in group A changed significantly (P < 0.05-0.001), and the indexes in group B didn't change significantly (P > 0.1-0.4). The therapeutic effect in group A was better than that in group B(P < 0.001). The results confirmed that the cognitive function of cerebral traumatic dementia patients was increased effectively with acupuncture at Houxi and Shenmen.

Acupuncture Points↗

PubMed1995

Platelet-activating factor induces NF-kappa B activation through a G protein-coupled pathway.

The capability of platelet-activating factor (PAF) to induce transcription factor activation was examined. In stably transfected Chinese hamster ovary cells expressing the PAF receptor (CHO-PAFR), PAF stimulation resulted in the nuclear expression of a DNA binding activity with specificity to the kappa B sequence. The p50 and p65 proteins, constituents of the prototypic nuclear factor kappa B (NF-kappa B), were identified as components of the DNA protein complexes by antipeptide antibodies in gel supershift as well as UV cross-linking experiments. PAF induced an initial decrease and subsequent increase of cytoplasmic I kappa B alpha levels, accompanied by up-regulation of the I kappa B alpha messenger RNA, a feature of NF-kappa B activation. PAF-induced kappa B binding activity was detected within 15 min after agonist stimulation, peaked at 30-40 min, and remained detectable by 2.5 h. SR 27417, a PAF receptor antagonist, blocked PAF-induced kappa B binding activity but not that induced by tumor necrosis factor-alpha (TNF alpha). Cholera toxin treatment markedly reduced PAF-induced kappa B binding activity, whereas pertussis toxin had no significant inhibitory effect. Neither of the two toxins affected the kappa B binding activity induced by TNF alpha in the same cells. In addition to the CHO-PAFR cells, PAF stimulated kappa B binding activity in the murine P388D1 macrophage and the human ASK.0 B cell lines that express endogenous PAF receptors. These results imply a potential role of PAF in the regulation of gene expression through a G protein-coupled transcription factor activation pathway.

Animals↗

PubMed1995

The major protein of guayule rubber particles is a cytochrome P450. Characterization based on cDNA cloning and spectroscopic analysis of the solubilized enzyme and its reaction products.

Guayule plants accumulate large quantities of rubber within parenchyma cells of their stembark tissues. This rubber is packed within discrete organelles called rubber particles composed primarily of a lipophilic, cis-polyisoprene core, small amounts of lipids, and several proteins, the most abundant of which is the M(r) 53,000 rubber particle protein (RPP). We have cloned and sequenced a full-length cDNA for RPP and show that it has 65% amino acid identity and 85% similarity to a cytochrome P450 known as allene oxide synthase (AOS), recently identified from flaxseed. RPP contains the same unusual heme-binding region and possesses a similar defective I-helix region as AOS, suggesting an equivalent biochemical function. Spectral analysis of solubilized RPP verifies it as a P450, and enzymatic assays reveal that it also metabolizes 13(S)-hydroperoxy-(9Z,11E)-octadecadienoic acid into the expected ketol fatty acids at rates comparable with flaxseed AOS. RPP is unusual in that it lacks the amino-terminal membrane anchor and the established organelle targeting sequences found on other conventional P450s. Together, these factors place RPP in the CYP74 family of P450s and establish it as the first P450 localized in rubber particles and the first eukaryotic P450 to be identified outside endoplasmic reticulum, mitochondria, or plastids.

Amino Acid Sequence↗

PubMed1995

Platelet-activating factor stimulates transcription of the heparin-binding epidermal growth factor-like growth factor in monocytes. Correlation with an increased kappa B binding activity.

Human peripheral blood monocytes responded to stimulation of platelet-activating factor (PAF) with up-regulation of the transcript for heparin-binding epidermal growth factor-like growth factor (HB-EGF), a potent mitogen for vascular smooth muscle cells. This function of PAF was observed at nanomolar concentrations of the ligand, starting at 30 min after stimulation. The PAF-induced up-regulation of HB-EGF mRNA was accompanied by an increase in kappa B binding activity. These functions of PAF appeared to be mediated through the cell surface PAF receptors, as two PAF receptor antagonists, WEB 2086 and L-659,989, blocked both the up-regulation of HB-EGF mRNA and kappa B binding activity induced by PAF. The antagonists, however, had no effect on phorbol ester-induced up-regulation of HB-EGF mRNA and kappa B binding activity. Pretreatment of monocytes with pertussis toxin inhibited these functions of PAF, whereas cholera toxin had no inhibitory effect. Pyrrolidine dithiocarbamate, an inhibitor for NF-kappa B activation, markedly reduced PAF-stimulated kappa B binding activity as well as up-regulation of HB-EGF mRNA. These results suggest a potential role of PAF in HB-EGF expression and provide evidence that this stimulation may occur through increased kappa B binding activity.

Bacterial Toxins↗