Biomedical subjects

P Chen

Publications and source records attributed to P Chen.

At least 253 records · Page 14Linked to original sources

PubMed1999

[Clinical applications of the anterolateral skin flap and the fascial flap in the lower leg].

OBJECTIVE: To introduce the applied anatomy, operative method and clinical application of the anterolateral skin flap and fascial flap of the lower leg. METHODS: Anatomic dissection was performed on 14 adult cadavers' legs and one amputated lower limb. The origin, course and distribution of cutaneous branches of the superficial peroneal vessels were traced. Four types of anterolateral flaps were designed in the lower leg including the island skin flap, the island fascial flap, the rectangular flap, and the cross-leg flap. Since 1988, twenty-six cases of leg defects(21 patients), chronic osteomyelitis of the tibia(3 cases) and defects on the back of the opposite heel and ankle(2 cases) were treated with the operative methods. RESULTS: All the flaps survived. Primary healing occurred in 23 and secondary in 3 cases. Twenty cases were followed-up for 4 months to 5 years. The flaps were growing well, the tibia fracture healed 3 months after the treatment and the chronic osteomyelitis of tibia had no recurrence. CONCLUSION: This flap is a useful method for repairing various defects in the leg and adjacent regions. It is simple, safe and reliable in manipulation and has minimal influence to the donor site.

Adolescent↗

PubMed1999

[Transforming growth factor-beta 1 inhibits the generation of dendritic cells from murine hematopoietic progenitor cells in vitro].

OBJECTIVE: To investigate the regulatory effect of transforming growth factor-beta 1 (TGF-beta 1) on the generation of dendritic cells (DCs) from hematopoietic progenitor cells (HPCs) and its cellular and molecular mechanisms. METHODS: Murine bone marrow derived-Lin c-kit+ HPCs were isolated by a cell sorter and cultured in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF), stem cell factor (SCF), tumor necrosis factor alpha(TNF alpha) and TGF-beta 1. The generation of DC precursors and mature DCs and their phenotypes were analyzed by a cell sorter, reverse transcription-polymerase chain reaction (RT-PCR), and allogenic mixed lymphocyte reaction (MLR). RESULTS: TGF-beta 1 could significantly inhibit the generation of DC precursors at day 6 and mature DCs at day 12 from murine Lin- c-kit+ HPCs stimulated with GM-CSF + SCF + TNF alpha or GM-CSF + SCF. Moreover, TGF-beta 1 markedly suppressed the expression of antigen peresenting molecule Ia and co-stimulatory molecule CD86 on the surface of cultured Lin- c-kit+ HPCs. Examination of RT-PCR showed that TGF-beta 1 could also inhibit the expression of MHC class II trans-activator (CTIIA) mRNA, which encodes a transcriptional factor to strictly control the expression of MHC class II antigens in the cultured cells. CONCLUSION: Our results suggest that TGF-beta 1 is an inhibitory cytokine for the generation of DC precursors and maturation of DC from HPCs, which may account for the cellular mechanisms of TGF-beta 1-mediated immuno-suppressive functions in vivo and in vitro.

Animals↗

PubMed1999

Selection and determination of specific and protective antigens of Mycobacterium tuberculosis.

OBJECTIVE: To select and identify the specific and protective antigens of Mycobacterium tuberculosis (M. tuberculosis) for searching a new approach to diagnose and treat tuberculosis. METHODS: Extract and culture filtrates of M. tuberculosis were obtained by ultrasonic treatment and millipore membrane filtration, respectively. The protein samples were tested with monoclonal antibody (MAb) and patient sera. The proteins showing positive reaction were sequenced on Beckman/LF 3200/peptide amino acid sequencer. RESULTS: Proteins of M. tuberculosis with molecular weight of 31 ku and 30 ku showed positive results when reacted with anti-M. tuberculosis MAb and sera of tuberculosis patients, but not with normal mouse serum and healthy human sera. N-terminal sequences of the 31 ku and 30 ku antigen were Ala Glu Val Asp Trp Leu Val Phe Ala Val and Phe Ser Arg Pro Gly Leu Pro Val Glu Try respectively. CONCLUSION: 31 ku and 30 ku proteins of M. tuberculosis are immune protective proteins. They play important or dominant roles in determination of immunorecognization.

Amino Acid Sequence↗

PubMed1999

[Effects of nitroglycerin on nitric oxide and endothelin derived from bronchial epithelial cells and alveolar macrophages in asthma].

OBJECTIVE: To investigate the changes of nitric oxide(NO) and endothelin(ET) derived from alveolar macrophages(AM) and bronchial epithelial cells (BEC), and the influences of nitroglycerin (NTG) on ET and NO in asthma. METHODS: BEC and AM from 15 patients with asthma exacerbation and 7 healthy control subjects were isolated and cultured for 48 hours. NO and ET levels in supernatants and expressions of iNOS-mRNA and ET-mRNA from cultured BEC and AM were examined by copper coated cadmiunm reduction, radioimmunoassay and in situ hybridization. RESULTS: The NO level and the ET level in supernatants, and expressions of iNOS-mRNA and ET-mRNA from BEC and AM of the untreated group were higher than those of other groups (P < 0.05, respectively); The NO level from BEC and AM in supernatants of NTG pretreated group were elevated significantly and the ET level and the expression of iNOS-mRNA and ET-mRNA were lower than those of asthma untreated group (P < 0.05, respectively); The NO, ET levels and expressions of iNOS-mRNA, ET-mRNA derived from AM were higher than those derived from BEC in patients with asthma (P < 0.05, respectively); expression of iNOS-mRNA from BEC and AM were negatively correlated with the NO level in supernatants of cultured BEC and AM from the group pretreated by NTG in asthma (r = -0.60, r = -0.59; P < 0.01). While the expression of iNOS-mRNA and ET-mRNA by BEC and AM from other groups were positively correlated with the NO level and the ET level in supernatants of BEC and AM in asthma (all r > or = 0.902; P < 0.01, respectively). CONCLUSIONS: BEC and AM from patients with asthma exacerbation secreted a large quantity of NO and ET because of the increased expressions of iNOS-mRNA and ET-mRNA; AM was the main source of elevated NO and ET in airways of patients with asthma exacerbation. NTG directly enhanced the production of NO and significantly inhibited the expression of ET-mRNA, and therefore decreased the production of ET.

Adult↗

PubMed1999

[Effect of cefodizime on cellular immunity in patients with lung cancer].

OBJECTIVE: To study the enhancing effect of cefodizime on cellular immunity of patients with lung cancer. METHODS: The parameters of cellular immunity in blood and pulmonary alveoli were investigated in 45 patients with lung cancer complicated with lower respiratory tract infection (LRTI) and 10 non-cancer patients with LRTI. Nitroblue tetrazolium (NBT) reaction of polymorphonuclear neutrophils (PMN), the percentage of natural killer (NK) cells, and that of CD4+ cells, ratio of CD4+/CD8+ in peripheral blood, OD value of alveolar macrophages phagocyting neutral red, and IL-1 beta (ng/L) in broncho-alveolar lavage flind (BALF) were determined. RESULTS: The parameters examined in cancer patients with LRTI were significantly improved after cefodizime treatment, approaching to those seen in non-cancer patients with LRTI. The therapeutic results were better in patients treated with cifodizime than in patients treated with ceftriaxonum. CONCLUSION: Cefodizime is a better choice of antibiotic for the treatment of lung cancer complicated with lower respiratory tract infection. Its enhancing effect on systemic and local immune functions plays a role.

Adult↗

PubMed1999

[The significance of detection of hepatitis C virus RNA in peripheral blood mononuclear cells of patients with chronic hepatitis C].

OBJECTIVE: To determine the role of peripheral blood mononuclear cells (PBMCs) in hepatitis C virus (HCV) infection. METHODS: HCV RNA, HCV antigen and Fas antigen were detected in PBMCs of 22 patients with chronic hepatitis C, 21 renal dialysis patients with anti-HCV positive and 12 health blood donors as normal controls. All specimens were studied by electronic microscope (EM). RESULTS: (1) The positive rate of HCV RNA in PBMCs of 22 patients with hepatitis C was 77.3% (17/22). (2) EM showed that HCV particles replicated in PBMCs of the patients with HCV infection, but not in the serum of patients with negative HCV RNA and healthy controls. (3) HCV RNA were positive both in the serum and PBMCs of 8 patients with HCV particles positive and had a close relationship with HCV antigen and Fas antigen. The expression of HCV and apoptosis were found in the cytoplasm of PBMCs in these 8 patients. CONCLUSION: (1) Hepatitis C virus could replicate in PBMCs and produce infectious HCV particles. (2) HCV in PBMCs may act as the source of reinfection for HCV and lead to persistent infection and recurrence.

Adult↗

PubMed1999

[Phacoemulsification with foldable intraocular lens implantation through a limbus tunnel incision].

OBJECTIVE: To advance and evaluate the technique and therapeutic effects of phacoemulsification with foldable intraocular lens implantation through a limbus tunnel incision. METHODS: The surgery was performed through a 3.2 limbus tunnel incision on 110 eyes of 103 patients with senile, complicated, congenital and traumatic cataracts. RESULTS: Postoperatively, the visual acuities with spherical correction or without correction were 0.5 or better in 90.0% of the eyes at one day, and 1.0 or better in 42.5%, 63.7% and 68.0% at one week, one month and three months respectively. The mean postoperative astigmatism was (1.00 +/- 0.68) D at one week and only 0.07D more than the mean preoperative one (P > 0.05). There was also no statistical difference between the mean preoperative astigmatism and postoperative astigmatism at one and three months, which were respectively (0.91 +/- 0.55) D and (0.83 +/- 0.57) D. The mean postoperative astigmatism was almost the same as compared between the scleral tunnel incision and clear corneal incision groups. CONCLUSION: The phacoemulsification with foldable intraocular lens implantation through a limbus tunnel incision can reduce postoperative astigmatism and shorten the period of visual rehabilitation as the operation through a scleral tunnel or a clear corneal incision, and in the mean time the former method can overcome the shortages of the latter two methods.

Adolescent↗

PubMed1999

[In vitro adherence of bacteria to intraocular lenses of different materials].

OBJECTIVE: To compare the in vitro adherence of different bacteria onto the surface of various intraocular lenses (IOLs). METHOD: Electron microscopic and bacterial culture quantitative methods were used to study the adherence of Staphylococcus (S) epidermidis, Staphylococcus aureus and Pseudomonas (P) aeruginosa onto the surface of PMMA and other three foldable IOL materials (HEMA, ACRY, SI). RESULTS: S. Epidermidis: HEMA < ACRY < SI < PMMA; S. aureus: HEMA was the least and PMMA was the most, no significant difference between ACRY and SI IOLs; P. aeruginosa: HEMA was the least while no significant difference among PMMA, SI and ACRY IOLs (P > 0.05). CONCLUSION: The foldable IOLs have the potent ability to reduce the infectious endophthalmitis after surgery of extraction of cataract with IOL implantation.

Acrylic Resins↗

PubMed1999

[A study on factors contributing to intelligence in 857 children].

OBJECTIVE: To study the main environmental factors affecting intelligence of children. METHODS: Intelligence quotients (IQ) were examined in 857 pupils of grades 1 to 6 in a primary school and categorized into four different classes. Data of relevant environmental factors were collected with questionnaires. Uni-variate and multivariate logistic regression analyses were performed to identify the factors influencing their IQ. RESULTS: There were 27 factors with statistical significance in uni-variable analysis. And, then they were analyzed with stepwise logistic regression method. Six variables, i.e., parents' education level, breast feeding during infancy, early education at home, nutritional status before three years old, single parent family and average scores at school, enter the regression model finally. CONCLUSION: Intelligence development in children was affected by a lot of factors, and good acquired environmental factors, especially their early nutrition, family background and education, would benefit for their intelligent development and improvement of their intelligent ability in children.

Child↗

PubMed1999

[A role of nitric oxide and endothelin in bronchial hyperreactivity in patients with mild and middle asthma].

OBJECTIVES: To probe into a role of nitric oxide(NO) and endothelin(ET) in bronchial hyperreactivity(BHR) in patients with mild and middle asthma. METHODS: MchPC20 was used as an index to evaluate BHR in the asthmatic patients. Endothelin and NO level in bronchial alveolar lavage fluid(BALF) obtained from 15 patients with attacking asthma(Group I), 8 patients with stable asthma (Group II) and 7 healthy control subjects (Group III) were examined by radioimmunoassay and copper coated cadmium reduction method, respectively. RESULTS: 1. MchPC20 and FEV1% in Group III were slightly higher than those in Group I (P < 0.05), and lower than those in Group III (P < 0.05), respectively; 2. NO and ET levels in BALF from Group I were higher than those from Group II and Group III (P < 0.05), respectively; 3. ET/NO ratio in Group I was higher than that in Group III (P < 0.05) and lower than that in Group II (P > 0.05); 4. NO and ET level in BALF from Group I were positively and negatively correlated with MchPC20, respectively(r = 0.83, P < 0.01; r = 0.75, P < 0.01); the correlation of NO and ET level in BALF from Group I was negative (r = 0.70, P < 0.01); 5. NO and ET levels in BALF and ET/NO ratio from Group II were slightly higher than those from Group III (P < 0.05), respectively. CONCLUSION: NO may improve and ET exacerbate BHR in patients with mild and middle asthma. Bronchial hyperreactivity of the patients with stable asthma displays lightly abnormal, which may be due to mild abnormality of NO, ET levels and ET/NO ratio in BALF.

Adult↗

PubMed1999

[One hundred and twenty-four cases of diffuse pulmonary disease diagnosed by transbronchial lung biopsy via fiberbronchoscope].

OBJECTIVE: To understand the diagnostic value in diffuse pulmonary disease examined with transbronchial lung biopsy(TBLB) via fiber bronchoscope. METHOD: One hundred and twenty-four cases of diffuse pulmonary disease were diagnosed with TBLB via fiberbronchoscope. RESULT: Confirmed diagnosis was obtained in 91 patients; the total diagnostic rate was 73.39%. The kinds of the diseases included lung cancer, lung tuberculosis, diffuse interstitial pulmonary fibrosis, pulmonary sarcoidosis, and pulmonary lesion in collageous diseases. There were no other serious complications except for bloody or blood-streaking sputum, and pneumothorax occurred occasionally. CONCLUSION: It is suggested that TBLB is an easy, safe and useful method for diagnosing diffuse pulmonary diseases.

Adolescent↗

PubMed1999

[Simultaneous analysis of alkali metals and alkaline earth metals in Chinese herbal medicine by ion chromatography].

A simple and rapid method for the analysis of cations by using ion chromatography was developed. The results showed that the content ratio of Na+, NH4+, K+, Mg2+, Ca2+ in rhizoma chuanxiong and semen zizyphi spinosae are different. The detection limits of cations (S/N = 3) were 0.001-0.013 mg/L. The calibration curves of peak areas for all analytes were linear over two or three orders of magnitude with a regression coefficient (r2) of 0.9995-1.0000.

Chromatography↗

PubMed1999

[Direct determination of purine bases in tea by reversed-phase high performance liquid chromatography].

A reversed-phase high performance liquid chromatographic(RP-HPLC) method for the direct determination of three purine bases(theobromin, theophyllin and caffeine) in tea was developed. An ODS column with Zorbax SB-C18(4.6 mm i.d. x 250 mm, 5 microns) was employed. The aqueous solution of methanol containing 0.05% of acetic acid and 0.25% of N,N-dimethylformamide(DMF) was used as eluent with a flow rate of 0.8 mL/min. In this method, the aqueous extract of tea can be injected into HPLC directly, but in current HPLC methods for purine bases the coexisted tea polyphenols must be pre-separated. The three purine bases in tea were separated without any interference from the coexisted tea polyphenols. This method is simple (without any special sample pretreatment) and sensitive with detection limits (S/N = 3) of 0.7, 0.9 and 1.8 mg/L for theobromin, theophyllin and caffeine respectively. The linear range of the calibration curve of peak area for the three purine bases were from 6 mg/L to 1,000 mg/L with a correlation coefficient (r) of 0.998-0.999.

Caffeine↗

PubMed1999

[Morpholgical, histological and histochemical observations on the effect of albendazole on encysted larvae of Trichinella spiralis in mice].

AIM: To study the mechanism of action of albendazole on encysted larvae of Trichinella spiralis in mice. METHODS: Twelve Kunming strain mice each infected with 200 T. spiralis larvae were equally divided into two groups. Six mice of the treatment group were treated with 30 mg of albendazole/kg daily for 5 days. Morphological, histological and histochemical methods were used. RESULTS: The encysted larvae of albendazole-treated group became significantly damaged, most worms were shrunken and surrounded by inflammatory cells. Histochemical study demonstrated that the glycogen and RNA content of the larvae in the treated group was decreased, the activities of SDH, ATPase, ACP were lower than those of the control group. CONCLUSION: Albendazole can affect the physiological function of Trichinella spiralis.

Albendazole↗

PubMed1998

The intrinsic radioresistance of glioblastoma-derived cell lines is associated with a failure of p53 to induce p21(BAX) expression.

Radiation is the primary modality of therapy for all commonly occurring malignant brain tumors, including medulloblastoma and glioblastoma. These two brain tumors, however, have a distinctly different response to radiation therapy. Medulloblastoma is very sensitive to radiation therapy, whereas glioblastoma is highly resistant, and the long-term survival of medulloblastoma patients exceeds 50%, while there are few long-term survivors among glioblastoma patients. p53-mediated apoptosis is thought to be an important mechanism mediating the cytotoxic response of tumors to radiotherapy. In this study, we compared the response to radiation of five cell lines that have wild-type p53: three derived from glioblastoma and two derived from medulloblastoma. We found that the medulloblastoma-derived cell lines underwent extensive radiation-induced apoptotic cell death, while those from glioblastomas did not exhibit significant radiation-induced apoptosis. p53-mediated induction of p21(BAX) is thought to be a key component of the pathway mediating apoptosis after the exposure of cells to cytotoxins, and the expression of mRNA encoding p21(BAX) was correlated with these cell lines undergoing radiation-induced apoptosis. The failure of p53 to induce p21(BAX) expression in glioblastoma-derived cell lines is likely to be of biologic significance, since inhibition of p21(BAX) induction in medulloblastoma resulted in a loss of radiation-induced apoptosis, while forced expression of p21(BAX) in glioblastoma was sufficient to induce apoptosis. The failure of p53 to induce p21(BAX) in glioblastoma-derived cell lines suggests a distinct mechanism of radioresistance and may represent a critical factor in determining therapeutic responsiveness to radiation in glioblastomas.

Apoptosis↗

PubMed1998

Endothelin-1 induces production of the neutrophil chemotactic factor interleukin-8 by human brain-derived endothelial cells.

Increased levels of endothelin-1 (Et-1), a potent vasoconstrictor, have been correlated with hypertension and neuronal damage in ischemic/reperfusion injury. The presence of polymorphonuclear cells (PMNs) in the brain has been shown to be directly responsible for this observed pathology. To address the question of whether Et-1 plays a role in this process, human brain-derived endothelial cells (CNS-ECs) were cultured with Et-1. The results demonstrate that Et-1 induces production of the neutrophil chemoattractant interleukin-8 (IL-8) twofold to threefold after 72 hours; mRNA was maximal after 1 hour of stimulation. Conditioned culture medium derived from Et-1-stimulated CNS-ECs induced a chemotactic response in the PMN migration assay. The inflammatory cytokines tumor necrosis factor-alpha (TNF) and IL-1beta functioned additively with Et-1 in increasing IL-8 production. In contrast, transforming growth factor-beta (TGF-beta), but not IL-10, completely abolished the effect of Et-1 on IL-8 production. However, Et-1 did not modulate intercellular adhesion molecule-1 (ICAM-1) expression. These data demonstrate that Et-1 may be a risk factor in ischemic/reperfusion injury by inducing increased levels of the neutrophil chemoattractant IL-8.

Brain Ischemia↗

PubMed1998

Ceramide generation by the Reaper protein is not blocked by the caspase inhibitor, p35.

The Reaper (Rpr) gene encodes a 65-amino acid protein that induces apoptosis in Drosophila by an unknown mechanism. A previous study reported that Rpr expression induced generation of the lipid second messenger ceramide and through use of the peptide caspase inhibitor N-benzyloxycarbonyl-VAD-fluoromethylketone(zVAD.fmk ) ordered ceramide generation downstream of caspases in SL2 cells (Pronk, G. J. , Ramer, K., Amiri, P., and Williams, L. T. (1996) Science 271, 808-810). The present study re-evaluates these events in SL2 cells transfected with cDNA for Rpr, with or without the baculovirus caspase inhibitor p35, under the control of the metallothionein promoter. Following copper addition, Rpr protein was detected at 1.5 h and maximal at 2.5 h. Ceramide generation and caspase activation occurred nearly simultaneously, each detectable at 2-2.5 h and maximal at 6 h. Ceramide levels increased from a base line of 5 pmol/nmol lipid phosphorus to a maximum of 10 pmol/nmol lipid phosphorus. Identical increases in ceramide were detected using the enzymatic 1,2-diacylglycerol kinase assay or the non-enzymatic o-phthalaldehyde derivatization high pressure liquid chromatography assay. In contrast, diacylglycerol levels were not increased by Rpr expression. Apoptosis, first detected at 4 h, was maximal at 16 h. Co-expression of p35 did not affect Rpr-induced ceramide generation, whereas caspase activation and apoptosis were abolished. In contrast, zVAD.fmk inhibited ceramide generation and apoptosis. These data show that Rpr-induced ceramide generation is upstream or independent of p35-inhibitable caspases and demonstrate differences in the actions of peptide and p35 caspase inhibitors.

Amino Acid Chloromethyl Ketones↗

PubMed1998

Chemosignal transduction in the vomeronasal organ of garter snakes: cloning of a gene encoding adenylate cyclase from the vomeronasal organ of garter snakes.

We previously reported that ES20-receptor binding activates phosphoinositide (PI) turnover, resulting in an increase in inositol-1,4,5-trisphosphate, which in turn mobilizes intracellularly stored calcium in the vomeronasal (VN) sensory epithelium of garter snakes. We also found that the activity of adenylate cyclase (AC) in the VN organ is very sensitive to Ca2+ but insensitive to calmodulin regulation. A 250-bp fragment of adenylate cyclase type VI (AC-VI) was obtained from brain cDNA of garter snake by RT-PCR with degenerate primers. The 250-bp fragments were amplified, cloned, and sequenced. Both Northern blot and RNase protection assays revealed that the vomeronasal organ (VNO) and brain contained more abundance of AC type VI than the main olfactory epithelium. A 3.8-kb cDNA was then cloned from the vomeronasal cDNA library of garter snakes and sequenced. The 5' cDNA was obtained by means of 5' RACE PCR and sequenced. We have successfully cloned a 5200-nucleotide cDNA from VNO of garter snakes containing an open reading frame++ encoding 1150 amino acids of AC-VI protein. The vomeronasal AC is termed AC(VN) . AC(VN) shows a high degree of homology with type VI AC of rat, mouse, or human. In situ hybridization with digoxigenin-labeled cRNA demonstrated that AC(VN) mRNA was abundant in the sensory epithelium but not in the nonsensory epithelium of the mushroom body of the vomeronasal organ of garter snakes.

Adenylyl Cyclases↗