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Biomedical subjects

F Peng

Publications and source records attributed to F Peng.

At least 37 records · Page 2Linked to original sources
PubMed2000

Cloning and characterization of a novel cDNA sequence encoding the precursor of a novel venom peptide (BmKbpp) related to a bradykinin-potentiating peptide from Chinese scorpion Buthus martensii Karsch.

Based on the amino acid sequence of a bradykinin-potentiating peptide (Bpp) (peptide K-12) from scorpion Buthus occitanus, a full-length cDNA sequence encoding the precursor of a novel venom peptide (named BmKbpp) related to this Bpp, has been isolated and analyzed. The cDNA encodes a precursor of 72 amino acid residues, including a signal peptide of 22 residues and an extra Arg-Arg-Arg tail at the C-terminal end of the precursor, which have to be removed in the processing step. The C-terminal region (21 residues) of the precursor is homologous (57% identical) with the sequence of peptide K-12. Thus, according to the primary structure of the BmKbpp precursor, there may be a propeptide between the signal peptide and the putative mature BmKbpp at the C-terminal region of the precursor.

Amino Acid Sequence↗
PubMed2000

[Observation on morphology and histology of Angelica dahurica (Fisch. ex Hoffm.) Benth. et Hook. f. var. formosana (Boiss.) Shan et Yuan in the process of in vitro cultivation and polyploid induction].

OBJECTIVE: To explore the relationship between morphogenesis and histogenesis in the process of in vitro cultivation of Angelica dahurica f. var. formosana, and determine the best period for its polyploid induction. METHOD: In the different periods of in vitro cultivation, the explants were obtained and their sections observed. When the adventitiousbuds began to differentiate, aqueous solution was applied for polyploid induction. RESULT: The adventitious buds were mainly externally originated and thus fit for polyploid induction. The most appropriate period for induction was around the 38th day of cultivation. CONCLUSION: Induction treatment can be used as an effective biotechnological approach to adventitious buds in the process of tissue cultivation.

Angelica↗
PubMed2000

[The relationship of cellular DNA content with clinical stage and biological features of colorectal cancer].

The purpose of this study was to explore the relationship of cellular DNA content with clinical stage and biological features of cancer. Flow cytometry was performed on fresh specimens from 86 patients from 1997 to 1998. Forty-five (53.3%) specimens were found to contain cells with abnormal DNA (DNA nondiploidy). Although none of the sex, age, site, differentiation variables correlated with flow cytometric DNA ploidy, nondiploidy was associated with Dukes' stage and lymph node metastasis. Duke's A stage tumors were more frequently diploid than were more advanced tumors, but no difference between Duke's B, C and D stages were observed. These findings suggest that ploidy is associated with some pathological factors.

Aged↗
PubMed2000

[Quantification analysis of vascular endothelial cells in human solid tumor].

Angiogenesis is essential for the growth and metastasis of solid tumors. Intratumoral microvessel count, which represents a measure of tumor angiogenesis, has been associated with prognosis of patients with a variety of malignancies. But till now, it is still a problem to quantitate the angiogenesis of tumors exactly. In this study, the endothelial cells in 20 solid tumors were conjugated with anti-CD34 monoclonal antibodies labelled with red-fluorescent substances, and were observed by fluorescence microscopy and quantitated by flow cytometry. The results of flow cytometry were analysed by t-test. The correlation was analysed between percentage of flow cytometry and vessel counts (light microscopy, x 200) in each tumor which was stained with anti-CD34 monoclonal antibodies and anti-VIII factor related antigen polyclonal antibodies by using immunohistochemistry. The results showed there was significant difference between the treatment group and control group in flow cytometry, and a significant correlation between the endothelial cells percentage by flow cytometry and the vessel counts by immunohistochemistry was observed, although the average vessel counts were approximately three times with CD34 staining as much as with VIII factor related antigen staining. These data indicate that flow cytometry as a novel method can quantitate angiogenesis of tumors exactly and quickly.

Antibodies, Monoclonal↗
PubMed1999

[Study on the correlation of silicosis with antioxidant and antioxidase].

Plasma vitamin C(P-VC), vitamin E(P-VE) and beta-carotene(P-beta-CAR) contents and the activities of superoxide dismutase(E-SOD), catalase(E-CAT) and glutathione peroxidase (E-GSH-Px) in erythrocyte in 73 silicosis patients and 60 healthy control subjects were measured. The average levels of P-VC, P-VE, P-beta-CAR, E-SOD, E-CAT and E-GSH-Px of patients were significantly lower than those of the controls (P < 0.001). All indexes were correlated to the course, condition and pulmonary function of silicosis patients. The results analyzed by stepwise regression showed that the correlation between course, condition and pulmonary function of patients and P-VE and E-SOD was close. The balance between oxidation and the antioxidation in silicosis patients may be disturbed, and oxygen free radical reaction may be pathologically exacerbated.

Adult↗
PubMed1999

Longitudinal changes in optic disc topography of adult patients after trabeculectomy.

OBJECTIVE: To study longitudinal changes in optic disc topography after trabeculectomy in adult patients. DESIGN: Prospective case series. PARTICIPANTS: Twenty-five eyes of 25 patients undergoing trabeculectomy were enrolled. INTERVENTION: Images of the optic disc were obtained preoperatively and approximately 2 weeks, 4 months, and 8 months after surgery by use of a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph). MAIN OUTCOME MEASURES: The topographic optic disc parameters (cup volume, cup area, rim volume, rim area, cup-disc area ratio, mean cup depth, maximum depth, cup shape, and height variation contour) were measured automatically for each image with the Heidelberg Retina Tomograph Software (version 1.11). RESULTS: Approximately 2 weeks after surgery, the mean preoperative intraocular pressure (IOP) of 19.3 mmHg (SD, 6.4 mmHg) decreased to 6.0 mmHg (SD, 3.6 mmHg), cup volume and mean cup depth decreased, height variation contour increased, and the cup shape parameter became more negative. Approximately 4 months after surgery, mean IOP was 9.7 mmHg (SD, 4.2 mmHg), and the only statistically significant change from preoperative values of optic disc parameters was in the cup shape measure. Approximately 8 months after surgery, there was no statistically significant change in any of the optic disc parameters compared with preoperative values, although IOP was 10.4 mmHg (SD, 5.9 mmHg). CONCLUSIONS: Changes in the optic disc that may be present 2 weeks after a trabeculectomy do not appear to persist 4 and 8 months later in eyes with advanced glaucomatous optic nerve damage, except for cup shape, which was different from preoperative values at 4 months but not at 8 months.

Aged↗
PubMed1999

Massive and widely distributed splenosis.

A 45-year-old man, seropositive for hepatitis C, was examined because his liver was palpable well below the costal margin. A CT examination revealed multiple nodules within the liver and also several sites of ectopic tissue. The patient had a splenectomy 25 years before. A radiocolloid study showed uptake, consistent with splenosis, in the thorax, abdomen, pelvis, and possibly the left arm. The magnitude of the ectopic tissue, and its multiple locations, indicated the ability of splenic cells to grow in a variety of body sites.

Humans↗
PubMed1999

[Hemorrheological status in patients with silicosis and its clinical significance].

OBJECTIVE: To study relationship between silicosis and hemorrheology and its clinical significance. METHODS: Varied indices for hemorrheology were measured in 85 male patients with silicosis, 45 male patients with chronic bronchitis and 100 healthy male subjects. RESULTS: Compared with the control group and the chronic bronchitis patient group, average hematocrit (Hct), whole blood apparent viscosity (eta(a)) at 4 s(-1) - 200 s(-1) shear rates, plasma viscosity (eta(p)), erythrocyte electrophoresis time (EET) and platelet electrophoresis time (PET) all significantly increased in patients with silicosis (P < 0.001). Hemorrheological indices in patients with silicosis increased with severity of disease, increased with decrease in their pulmonary function, and were all significantly higher than those in the control group (P < 0.01 approximately equal 0.001). Stepwise regression analysis showed that severity of disease correlated closely to Hct, eta(a) at 4 s(-1) - 200 s(-1), EET and PET, and that pulmonary function status in patients with silicosis and their courses correlated closely to Hct, eta(a) at 4 s(-1) - 200 s(-1), eta(p), EET and PET. CONCLUSIONS: Blood of patients with silicosis was in highly viscose status, which was easy to be complicated with multiple diseases.

Aged↗
PubMed1999

[Experiment on polyploid induction of Angelica dahurica var. formosana].

Colchicine solution was applied to the primary adventitious buds of Angelica dahurica var. formosana in vitro to induce the polyploid. Compared with non-treated plantlet, the morphology, microhisology, and chromosome number of treated plantlets are varied. It proved that the polyploid induction was effective.

Aneugens↗
PubMed1998

Reciprocal changes in hypothalamic receptor binding and circulating leptin in anorectic tumor-bearing rats.

Although reduced biological activity of the obese gene product, leptin, has been associated with obesity, little information is available concerning leptin alterations during anorexia. Therefore, we measured circulating leptin concentrations and hypothalamic leptin binding in anorectic tumor-bearing and pair-fed control rats. Plasma concentrations of leptin decreased in tumor-bearing rats early in the course of tumor growth, and fell to nearly non-detectable levels during severe anorexia. The pair-fed control rats that ate the same amount of food as did the anorectic tumor-bearing rats exhibited a 50% decrease in plasma leptin concentration. Concentrations of free fatty acids were elevated in both tumor-bearing and pair-fed groups, while circulating levels of triglycerides were increased only in anorectic tumor-bearing rats. Leptin receptor density was doubled in the hypothalamus of tumor bearing rats, while binding affinity was decreased by 50%. These results suggest that peripheral leptin production is down-regulated, perhaps due to increased lipolysis in tumor-bearing rats. It appears that hypothalamic leptin systems up-regulate receptor numbers in response to decreased blood leptin level, however, the decrease in binding affinity may compensate for these alterations. Therefore, the influence of leptin on hypothalamic neuropeptide Y feeding systems may be minimal in anorectic tumor-bearing rats.

Animals↗
PubMed1998

Activation of the cyclic AMP pathway by alpha-melanotropin mediates the response of human melanocytes to ultraviolet B radiation.

A hallmark of sun exposure is increased melanin synthesis by cutaneous melanocytes which protects against photodamage and photocarcinogenesis. Irradiation of human keratinocytes or melanocytes with ultraviolet (UV) rays stimulates the synthesis and release of alpha-melanotropin (alpha-MSH) and adrenocorticotropic hormone (ACTH), which induce cyclic AMP (cAMP) formation and increase the proliferation and melanogenesis of human melanocytes. We report that stimulation of cAMP formation is obligatory for the melanogenic response of cultured normal human melanocytes to UVB radiation. In the absence of cAMP inducers, UVB radiation inhibited, rather than stimulated, melanogenesis. UVB radiation (28 mJ/cm2) arrested melanocytes in the G1 phase of the cell cycle, and concomitant treatment with 0.1 microM alpha-MSH enhanced their proliferation but did not increase the surviving fraction. Irradiation with UVB, with or without alpha-MSH, caused prolonged expression of p53 and p21(waf-1, cip-1), maintained pRB in a hypophosphorylated state, and reduced the expression of Bcl2. However, alpha-MSH allowed UVB-irradiated melanocytes to enter S phase, suggesting that alpha-MSH acts as a mitogen rather than a survival factor, and that overexpression of p53 is mainly a signal for cell death. Our results underscore the importance of the cAMP pathway and its physiological inducers in mediating the response of human melanocytes to UV radiation.

Cyclic AMP↗
PubMed1997

Identification of functional GRP-preferring bombesin receptors on human melanoma cells.

Bombesin was originally isolated from amphibian skin, whereas its mammalian counterpart, gastrin-releasing peptide (GRP), was first identified in the nervous system of the gastrointestinal tract. Whether GRP is present in the human skin is not known. Bombesin-like peptides are also known to modulate growth. We therefore investigated whether human melanoma cell lines express functional GRP-preferring bombesin receptors and whether they alter growth or other specific cellular functions of these tumour cells. GRP receptor mRNA was found in HBL, D-10, Me-28 and A375-6 cell lines, but only A375-6 cells express a large number of high-affinity binding sites for [125I]-[Tyr4] bombesin (K(d) 0.31 +/- 0.04 nmol L(-1), 3880 +/- 429 binding sites per cell). Bombesin dose-dependently increased cytosolic calcium, but did not alter interleukin (IL) 1beta-induced reduction of cell viability or IL-6 secretion, both A375-6-specific cell functions. Growth of A375-6 cells was not altered by bombesin or the specific GRP receptor antagonist BIM26226 as measured by [3H]-thymidine incorporation or methylene blue assay, whereas insulin alone or in combination with other potential growth factors dose-dependently stimulated growth of these cells. The newly characterized GRP-preferring bombesin receptors on highly malignant human melanoma cells could initiate studies of growth effects on solid tumours or in vivo scanning using radiolabelled tracers.

Bombesin↗
PubMed1996

APC-resistance as measured by a Textarin time assay: comparison to the APTT-based method.

Protein C is a major regulatory protein critical to physiologic anticoagulation. When activated, it selectively degrades the activated forms of factors V and VIII, thereby, down-regulating blood coagulation. Using an activated partial thromboplastin time (APTT) assay, Dahlback et al. recently reported that some individuals with thrombophilia show a poor in vitro anticoagulant response to activated protein C (APC-Resistance). Subsequent studies identified a point mutation in the gene for factor V as the underlying cause of APC-Resistance. The incidence of APC-Resistance in patients with recurrent thromboembolic events approaches 50%. The APC-Resistance phenotype is also present in approximately 5% of normal Caucasian subjects. In an attempt to develop a more sensitive and specific test system, we evaluated an assay based on Textarin(Pentapharm, Basel, Switzerland). Textarin, a protein fraction of Pseudonaja textilis venom (Australian Eastern Brown Snake) activates prothrombin in the presence of phospholipid (PL), factor V and calcium ions. Based on Textarin's requirement for factor V, we developed a Textarin time assay to test for APC-Resistance. We evaluated this test system in normal subjects and the following patient populations: stable orally anticoagulated, previously diagnosed factor V Leiden, and therapeutically heparinized samples. We found the Textarin assay to be a sensitive and specific test system to identify APC-Resistance. The phenotypic Textarin APC-Resistance test correlated more closely with the genotypic abnormality of factor VR506Q than the APTT-APC-Resistance test.

Anticoagulants↗
PubMed1996

Pulmonary embolism and premature labor in a patient with both factor V Leiden mutation and methylenetetrahydrofolate reductase gene C677T mutation.

Multiple risk factors for thrombosis were found in a 21 year old female who experienced three episodes of premature labor and developed severe pulmonary embolism during her third pregnancy. This patient is heterozygous for factor V Leiden mutation and homozygous for methylenetetrahydrofolate reductase (MTHFR) gene nucleotide 677 C to T (C677T) point mutation. This is a first report of the concordance of homozygous MTHFR C677T mutation in an individual with factor V Leiden mutation. This new case provides further evidence that synergism of multiple genetic and acquired risk factors is often encountered in young patients with symptomatic venous thrombosis.

Adult↗
PubMed1996

Bayesian inference for hierarchical mixtures-of-experts with applications to regression and classification.

This paper studies the problems of inference and prediction in a class of models known as hierarchical mixtures-of-experts (HME). The statistical model underlying an HME is a mixture model in which both the mixture coefficients and the mixture components are generalized linear models. Bayesian inference regarding an HME's parameters is presented in the contexts of regression and classification using Markov chain Monte Carlo methods. A benefit of this Bayesian approach is the ability to obtain a sample from the posterior distribution of any functional of the parameters of the given model. In this way, more information is obtained than provided by a point estimate. The methods are illustrated on a nonlinear regression problem and on a breast cancer classification problem. The results indicate that the HME showed good prediction performance, and also gave the additional benefit of providing for the opportunity to assess the degree of certainty of the model in its predictions.

Algorithms↗