Biomedical subjects

J Feng

Publications and source records attributed to J Feng.

At least 37 records · Page 2Linked to original sources

PubMed2001

Phase transitions of hydroxyapatite coatings during post-heat treatment and their performances under ultrasonic tests.

Highly or completely crystalline hydroxyapatite (HA) coatings can be obtained by post-heat treatment. We have developed a high-temperature (490 degrees C) and a low-temperature (125 degrees C) heat treatment to improve the crystallinity of HA coatings. Both methods transform entirely the amorphous phase into crystalline HA. However, the microstructure of the coating is dependent on the post-heating method. Nanocrystalline HA is about half of the component of the low-temperature heated coating while highly crystalline HA dominates the high-temperature heated coating, as detected by X-ray diffraction. The effects of both methods on the disintegration of the coatings were tested by ultrasonic treatment. The high-temperature heated coatings exhibited poor integrity while the low-temperature heated coatings exhibited better integrity, possibly due to their different microstructure. SEM revealed that the coatings disintegrated via different mechanisms: the high-temperature heated coatings failed via crack initiation and propagation while the low-temperature heated coatings failed via pit formation and subsequent widening.

Coated Materials, Biocompatible↗

PubMed2001

Arachidonic acid-induced Ca2+ sensitization of smooth muscle contraction through activation of Rho-kinase.

Arachidonic acid activates isolated Rho-kinase and contracts permeabilized smooth muscle fibres. Various assays were carried out to examine the mechanism of this activation. Native Rho-kinase was activated 5-6 times by arachidonic acid but an N-terminal, constitutively-active fragment of Rho-kinase, expressed as a glutathione-S-transferase (GST) fusion protein and including the catalytic subunit (GST-Rho-kinase-CAT), was not. GST-Rho-kinase-CAT was inhibited by a C-terminal fragment of Rho-kinase and arachidonic acid removed this inhibition. These results suggest that the C-terminal part of Rho-kinase, containing the RhoA binding site and the pleckstrin homology domain, acts as an autoinhibitor. It is suggested further that activation by arachidonic acid is due to its binding to the autoinhibitory region and subsequent release from the catalytic site. Arachidonic acid, at concentrations greater than 30 microM, increases force in alpha-toxin-permeabilized femoral artery but not in Triton X-100-skinned fibres. The content of Rho-kinase in the latter was lower than in alpha-toxin-treated or intact fibres. The arachidonic acid-induced contraction was not observed at a pCa above 8.0 and was inhibited by Y-27632 and wortmannin, inhibitors of Rho-kinase and myosin light-chain kinase (MLCK), respectively. The activation of Rho-kinase and subsequent phosphorylation of the myosin phosphatase target subunit inhibits myosin phosphatase and increases myosin phosphorylation.

Amides↗

PubMed2001

Identification of rice black-streaked dwarf fijivirus in maize with rough dwarf disease in China.

Three virus isolates from maize with rough dwarf in different provinces in China were analyzed at the molecular level. When compared to an isolate from diseased rice plants in Hubei Province, all four isolates had identical genomic RNA electrophoretic profiles, which were composed of ten double-stranded (ds) RNAs. Full-length cDNAs of segment 10 (S10) from each of the four isolates were cloned by RT-PCR and the complete sequences were determined. Analysis of the sequences revealed that each consisted of 1801 nucleotides and contained a single open reading frame (ORF) which potentially encoded a protein with 558 amino acids. Further, the sequences showed more than 97.0% and 98.0% identity at nucleotide and amino acid levels, respectively. In addition, their identities to rice black-streaked dwarf virus S10 were significantly higher than those to maize rough dwarf virus S10. Based on these results, it is suggested that the virus which causes this maize disease in China is rice black-streaked dwarf virus.

China↗

PubMed2001

Mutational analysis of the candidate tumor suppressor gene ING1 in Indian oral squamous cell carcinoma.

ING1, a recently identified candidate tumor suppressor gene, involved in the p53 signaling pathway is mapped at chromosome 13q34. Since loss of heterozygosity at 13q34 has been reported in squamous cell carcinoma of head and neck, we screened for mutations in ING1 by polymerase chain reaction-single strand conformation polymorphism in 71 oral squamous cell carcinomas (OSCC) from India, 15 of which were known to harbor p53 mutations. A single polymorphism (G to A) was detected in 14 (19.7%) of the tumors analyzed. No mutation was observed in any of the 71 OSCCs analyzed. These results suggest that ING1 is not a target for mutational inactivation in OSCC of Indians.

Areca↗

PubMed2001

Mitochondrial electron transport is a key determinant of life span in Caenorhabditis elegans.

Increased protection from reactive oxygen species (ROS) is believed to increase life span. However, it has not been clearly demonstrated that endogenous ROS production actually limits normal life span. We have identified a mutation in the Caenorhabditis elegans iron sulfur protein (isp-1) of mitochondrial complex III, which results in low oxygen consumption, decreased sensitivity to ROS, and increased life span. Furthermore, combining isp-1(qm150) with a mutation (daf-2) that increases resistance to ROS does not result in any significant further increase in adult life span. These findings indicate that both isp-1 and daf-2 mutations increase life span by lowering oxidative stress and result in the maximum life span increase that can be produced in this way.

Amino Acid Sequence↗

PubMed2001

Preoperative high-dose chemotherapy with peripheral blood stem cell support as a primary management of locally advanced breast cancer.

Locally advanced breast cancer (LABC) has a poor prognosis with a high risk of local recurrence and distant metastasis. Preoperative combined chemotherapy with or without granulocyte colony-stimulating factor (G-CSF) support does not improve the long-term survival rate. In our report, two patients with LABC received preoperative high-dose chemotherapy with peripheral blood stem cell support (HDC/PBSCs). Prior to high-dose chemotherapy with peripheral blood stem cell support, they both received induction chemotherapy of cyclophosphamide, epirubicin and 5-fluorouracil (FEC) for two cycles which resulted in a partial response. PBSC mobilization and collection were carried out following the second cycle of induction chemotherapy followed by G-CSF. High-dose cyclophosphamide (2500 mg/m2), carboplatin (600 mg/m2) and etoposide (600 mg/m2) were administered with PBSC support. A radical mastectomy was performed followed by adjuvant chemotherapy with FEC regimen for four cycles, followed by local irradiation, and endocrine therapy with tamoxifen. Both patients achieved a remarkable response in the primary lesion after HDC/PBSCs and tolerated the whole treatment well. Preoperative HDC/PBSCs as a new strategy in the treatment of LABC seems practical but it needs to be studied more deeply.

Adult↗

PubMed2001

An in-frame deletion in the alpha(2C) adrenergic receptor is common in African--Americans.

alpha(2) adrenergic receptors are activated by adrenaline and noradrenaline, and three subtypes (ie, A, B, C) have differential affinities for antagonists and medications. The alpha(2c) adrenergic receptor (ADRA2C), located on chromosome 4p16.3, is a candidate gene for schizophrenia because it binds clozapine, an atypical neuroleptic useful for treatment-resistant schizophrenia. In addition, ADRA2C binds clonidine which is prescribed for three psychiatric diseases. This report communicates the findings of the genetic scanning of this gene of very tough GC content. The complete coding sequences and splice junctions were scanned with [DOVAM]-S in 104 schizophrenics, and pilot probes of patients with alcoholism (41 patients), cocaine abuse (25 patients), puerperal psychosis (30 patients), attention deficient/hyperactivity disorder (25 patients) and autism (25 patients). Six sequence variants were found, including five silent polymorphisms (allele frequencies 0.6--25%) and an in-frame deletion of a homologous repeat at nucleotides 967--978 (ie, TIDRU(1)). Genotyping of the normal two repeat unit of the Third Intracytoplasmic Domain Repeat Unit (TIDRU(2)) and the deleted variant (TIDRU(1)) revealed that TIDRU(1) had allelic frequencies of 39% (11/28) and 3.5% (6/172) in African-American and Caucasian schizophrenics, respectively, and it occurred with equal frequency in controls (44%, 31/70 and 3.0%, 6/198). TIDRU(1) occurs at a location similar to the third intracytoplasmic 48-nucleotide repeat unit in the DRD4 that is associated with ADHD. Although these data do not suggest an association of TIDRU(1) with schizophrenia, additional studies are needed to see whether TIDRU(1) confers a clinical phenotype.

Black People↗

PubMed2001

The biomechanical, morphologic, and histochemical properties of the costal cartilages in children with pectus excavatum.

BACKGROUND/PURPOSE: The cause of the pectus excavatum (PE) remains unclear, although some results of research have indicated that the disturbance of the sternum or costal cartilage might be responsible for this deformity. But no decisive evidence has been gained. The authors have analyzed the biomechanical, morphologic, and histochemical properties of the cartilage in PE and intend to support the belief that the disturbance of the cartilage might contribute to the development of PE. METHODS: Thirty-eight specimens of the sixth cartilage were obtained at operation for the PE group (aged from 3 to 6 years; mean, 4.2 years). And 28 specimens of the control group (aged from 3 to 6 years; mean, 4.4 years) were gained from routine postmortem examinations in which the cause of death was unlikely to have affected the cartilage. The biomechanical test was carried out in a material testing machine (Shimadzu AG-10TA, Tokyo, Japan). The relation curve of load-deformation in tensile and compressive tests and the curve of load-time in the flexuous test were recorded automatically. The values of the ultimate strength and strain were calculated from this relation curve. The specimens also underwent H&E staining. The values of the area, circumference, mean diameter, maximal diameter, and morphologic factor of the cell and the nucleus of the cartilage in superficial and deep area were determined with the help of image analysis software (GT-2 model, China). The superficial zone (SZ) and deep zone (DZ) of the cartilage were examinated with electron microscopy (JEM-100SX, Japan). The distribution and intensity of type II collagen was shown by immunohistochemistry staining and analyzed with the image analysis software (GT-2 model, Huakang Co, Chengdu, China). The extent and distribution of proteoglycan were analyzed after Safranin-O and periodic acid shiff (PAS) staining. RESULTS: The mean strength of the costal cartilage in the experimental group was less than that in the control group in terms of tension, compression, and flexure (P <.05). The shape of the stress-strain curve for tension and compression in the experimental group was different from the control group. The fracture load in the experimental group was less than in the control group in tension (1.5 MPa versus 2.8 MPa) and in compression (.2 MPa versus 8.3 MPa). The time of fracture in experimental group was 30 seconds compared with 38 seconds in control group. No denaturation or necrosis could be found in light microscopical examination. There was no manifestation of hyperplasia or hypoplasia in the costal cartilage of the PE group. In SZ and DZ areas, the pattern and the number of mitochondria, endoplasmic reticulum, and Golgi in the experimental group were the same as the control group in transmission electron microscopy. Furthermore, the distribution and the number of proteoglycan in the 2 groups did not show a significant difference both in SZ and DZ areas. Although the distribution of the collagen in SZ areas was normal, this pattern was disturbed in DZ areas in the experiment group. The results of type II collagen immunohistochemistry examination was concordant with that change. No significant difference between control and experimental group could be seen in Safranin-O and PAS staining for proteoglycan. CONCLUSIONS: The biomechanical stability of the cartilage was decreased in the PE group. This might be caused by the disorderly arrangement and distribution of the collagen in the cartilage of PE patients. J Pediatr Surg 36:1770-1776.

Biomechanical Phenomena↗

PubMed2001

Phenotypic and suppressor analysis of defecation in clk-1 mutants reveals that reaction to changes in temperature is an active process in Caenorhabditis elegans.

Mutations in the Caenorhabditis elegans maternal-effect gene clk-1 affect cellular, developmental, and behavioral timing. They result in a slowing of the cell cycle, embryonic and postembryonic development, reproduction, and aging, as well as of the defecation, swimming, and pharyngeal pumping cycles. Here, we analyze the defecation behavior in clk-1 mutants, phenotypically and genetically. When wild-type worms are grown at 20 degrees and shifted to a new temperature, the defecation cycle length is significantly affected by that new temperature. In contrast, we find that when clk-1 mutants are shifted, the defecation cycle length is unaffected by that new temperature. We carried out a screen for mutations that suppress the slow defecation phenotype at 20 degrees and identified two distinct classes of genes, which we call dsc for defecation suppressor of clk-1. Mutations in one class also restore the ability to react normally to changes in temperature, while mutations in the other class do not. Together, these results suggest that clk-1 is necessary for readjusting the defecation cycle length in response to changes in temperature. On the other hand, in the absence of clk-1 activity, we observe temperature compensation, a mechanism that maintains a constant defecation period in the face of changes in temperature.

Animals↗

PubMed2001

Systematic screening for mutations in the glycine receptor alpha2 subunit gene (GLRA2) in patients with schizophrenia and other psychiatric diseases.

The glycine receptor, which is a member of the ligand-gated ion channel superfamily, mediates synaptic inhibition in the spinal cord and other brain regions. This superfamily has been implicated in the pathogenesis of schizophrenia and other psychiatric diseases. The complete coding sequence and splice junctions of the GLRA2 gene were scanned by DOVAM-S, a form of SSCP analysis with sufficient redundancy to detect virtually all mutations. Those analyses were performed in 113 patients with schizophrenia, and in pilot studies of patients with bipolar illness, alcoholism, puerperal psychosis, autism, and attention-deficit hyperactivity disorder (533 kb total scanned sequences). We detected three sequence changes in the coding region, all resulting in silent mutations: C894T in exon 5, C1134T in exon 7, and C1476T in exon 9. These do not alter the structure or the expression of the protein. It is unlikely that mutations in the coding region and splice junction of GLRA2 gene are associated with schizophrenia and other psychiatric diseases.

Alcoholism↗

PubMed2001

Stable transfection of the bovine NRAMP1 gene into murine RAW264.7 cells: effect on Brucella abortus survival.

Genetically based natural resistance to brucellosis in cattle provides for novel strategies to control zoonotic diseases. Bovine NRAMP1, the homologue of a murine gene (Bcg), has been identified as a major candidate for controlling the in vivo resistant phenotype. We developed an in vitro model for expression of resistance- and susceptibility-associated alleles of bovine NRAMP1 as stable transgenes under the regulatory control of the bovine NRAMP1 promoter in the murine RAW264.7 macrophage cell line (Bcg(s)) to analyze the regulation of the NRAMP1 gene and its role in macrophage function. We demonstrated that the 5'-flanking region of bovine NRAMP1, despite the lack of TATA and CAAT boxes, has a functional promoter capable of driving the expression of a transgene in murine macrophages. A polymorphism within a microsatellite in the 3' untranslated region critically affects the expression of bovine NRAMP1 and the control of in vitro replication of Brucella abortus but not Salmonella enterica serovar Dublin. We did not observe any differences in the production of NO by resting or gamma interferon (IFN-gamma)- and IFN-gamma-lipopolysaccharide (LPS)-treated transfected cell lines, yet the resistant transfected cell lines produced significantly less NO than other cell lines, following stimulation with LPS at 24 and 48 h.

3' Untranslated Regions↗

PubMed2001

Functional implication of spare ATP-sensitive K(+) channels in bladder smooth muscle cells.

ATP-sensitive K(+) (K(ATP)) channels play important roles in the regulation of excitability in urinary bladder smooth muscle cells. Patch-clamp studies revealed that the current density was about 9-fold higher in the pig bladder smooth muscle cells, compared with guinea pig, although the rank order of potencies for suppression of electrical field-stimulated contraction of bladder strips by K(ATP) channel openers (KCOs) showed a nearly 1:1 correlation between pig and guinea pig. To investigate the existence of spare K(ATP) channels, P1075-evoked current and membrane potential responses were studied in bladder smooth muscle cells. During a 10-min exposure to P1075 (10 microM), K(ATP) currents ran down by approximately 30.5%, whereas membrane hyperpolarization remained constant. P1075 evoked membrane hyperpolarization with an EC(50) value of 0.20 +/- 0.02 microM, comparable to that required for smooth muscle relaxation (EC(50) = 0.11 +/- 0.01 microM). However, these potencies are 6-fold higher than those required for current activation (EC(50) = 0.73 +/- 0.4 microM). These findings demonstrate that the reduction in membrane excitability by KCOs is associated with membrane hyperpolarization, and that a low amount of K(ATP) channel opening is sufficient to suppress bladder smooth muscle contraction.

Acetylcholine↗

PubMed2001

Human papillomavirus infection at the United States-Mexico border: implications for cervical cancer prevention and control.

The United States-Mexico border is a region comprised of a country with one of the highest rates of invasive cervical cancer (Mexico) and a country with one of the lowest rates (United States). Recent evidence clearly indicates that human papillomavirus (HPV) infection is the cause of cervical cancer. The distribution of specific types of HPV is known to vary in different regions of the world, as do the cofactors that may inhibit or promote HPV carcinogenesis. Estimating the prevalence of oncogenic HPV is needed for guiding vaccine development. The purpose of this study was to determine the prevalence of oncogenic and nononcogenic HPV types and risk factors for HPV among women residing along the United States-Mexico border. A cross-sectional study of 2319 women, ages 15-79 years, self-referring for gynecological care was conducted between 1997 and 1998. HPV was detected by PCR using the PYGMY 09/11 L1 consensus primer, and HPV genotyping was conducted using the reverse line blot method. Overall, the HPV prevalence was 14.4% with no significant differences observed by country after adjustment for age. HPV 16 was the most commonly detected HPV type in both the United States and Mexico. Among women with high-grade squamous intraepithelial lesions, HPV types 58, 45, 51, 31, 35, 55, and 73 were most common in Mexico, and HPV types 18, 31, 35, 51, 52, and 58 were most common in the United States. In both countries, HPV prevalence declined linearly with age from 25% among women ages 15-19 years to 5.3% among women 56-65 years. Factors significantly independently associated with HPV infection were older age [adjusted odds ratio (AOR) = 0.15 for ages 56-65 years compared with those 15-19 years], a marital status other than married (AOR = 1.58-3.29), increased numbers of lifetime male partners (AOR = 3.8 for > or =10 partners compared with 1 partner), concurrent infection with Chlamydia trachomatis (AOR = 1.79), ever use of Norplant (AOR = 2.69), and current use of injectable contraceptives (AOR = 2.29). Risk factors for HPV infection did not differ by country. Results from this study suggest that in addition to HPV 16 and 18, HPV types 31, 45, 51, and 58 should be considered for inclusion in an HPV prevention vaccine for distribution in Mexico.

Adolescent↗

PubMed2001

[Early postoperative complications of choledochal cyst excision and reconstruction of biliary tract].

OBJECTIVE: To study the early postoperative complications of choledochal cyst excision with reconstruction of the biliary tract. METHODS: In last 10 years, 173 patients aged from 27 days to 14 years (mean = 2.4 years) were operated on with procedures of choledochal cyst excision and biliary tract reconstruction by jejunointerposition between the liver hilum and duodenum or Roux-en-Y hepaticojejunostomy in our hospital. Amongst these 173 patients, 16 were found to suffer from postoperative complications. Therefore, their clinical data were retrospectively analyzed, and the prevention and treatment of the early postoperative complications discussed. RESULTS: The morbidity of early postoperative complications was 9.3% (16/173). The early complications included biliary leakage in 10 patients, wound dehiscence of abdominal wall in 3, hepatic failure in 1, pancreatic fistula in 1, and postoperative enteric intussusception in 1. The morbidity of early postoperative complications in infants younger than 1-year old was significantly higher than that in children(chi 2 = 15.78, P < 0.01). However, there was no significant difference in the morbidity of early postoperative complications between patients undergoing biliary tract reconstruction by jejunal segment interposition and those undergoing that by Roux-en-Y hepaticojejunostomy (chi 2 = 0.07, P > 0.05). The total mortality in all the operated patients was 2.3% (4/173). Three patients died from biliary leakage and 1 from postoperative hepatic failure. CONCLUSIONS: Biliary leakage, wound dehiscence of abdominal wall and hepatic failure are major early postoperative complications. The morbidity in infants younger than 1-year old is higher than in children. The preoperative treatment of biliary tract infection, hypohepatia, and surgical skills during operation should be emphasized. Reoperation for biliary leakage should not be delayed and mycotic cholangitis after biliary leakage needs more attention. Tension suture in the fascial space of the abdominal wall is useful for the prevention and treatment of abdominal wall dehiscence.

Adolescent↗

PubMed2001

Clinical significance of examining IL-2R in peripheral blood lymphocytes of patients with gastric cancer.

OBJECTIVE: To understand the clinical significance of membrane receptors of interleukin-2 (CD25) in peripheral blood lymphocytes (PBL) of patients with gastric cancer. METHODS: CD25 percentages in PBL from 110 patients with gastric cancer and 100 normal individuals were examined by flow cytometry. Results were analyzed clinically and pathologically. RESULTS: Mean CD25% in PBL from normal individuals and patients with gastric cancer were 17.24 +/- 5.33 and 22.47 +/- 6.82, respectively, and the difference was significant (P < 0.01). Abnormally elevated CD25% in PBL from patients with gastric cancer were correlated with tumor site, macropathology type, tumor size, differentiation degree and clinical stage. CONCLUSION: Measuring CD25% in PBL from gastric cancer patients before surgery may provide a reference for diagnosis, immune treatment and judging prognosis.

Adult↗

PubMed2001

[Analysis of the risk factors and drug resistance of lower respiratory tract infection by Flavobacteria].

OBJECTIVE: To investigate risk factors of 26 cases with lower respiratory tract infection caused by Flavobacteria and its antimicrobial susceptibility in vitro. METHODS: Retrospective study of the clinical materials of 26 cases of lower respiratory tract infection caused by Flavobacteria. Antimicrobial susceptibility (MIC) was determined with the method of agar dilution. RESULTS: All of 26 cases suffered from underlying diseases, among them malignant tumors were most common (31%) illness. 50% of the cases were mixed infections. Risk factors of infections were application of multiple antibiotics (81%), host immune suppression (77%), invasive manasements (31%), and prolonged hospitalization. No specific clinical manifestations and chest X-ray appearance revealed. Isolates were highly resistant to most of antimicrobial agents. Ciprofloxacin, trimethoprim-sulfamethoxazole and piperacillin are the most sensitive agents. CONCLUSIONS: Lower respiratory tract infection caused by Flavobacteria developed most commonly in patients who suffered from various underlying diseases, immunodeficiency, and longtime antibiotic overuse. Clinical isolates were highly resistant to most kinds of antimicrobial agents.

Adolescent↗

PubMed2001

[Changes in the activity of platelet L-arginine/nitric oxide pathway in hypercholesterolemia patients].

OBJECTIVE: To investigate the changes of the platelet L-arginine (L-Arg)/nitric oxide (NO) pathway in hypercholesterolemia patients. METHODS: The platelet NO production in 21 hypercholesterolemia (HC) patients and 26 normal individuals was assayed by spectrum, the NOS activity and the transportation of L-Arg were determined by (3)H-labelled L-Arg. RESULTS: The NO production in hypercholesterolemic platelets [(24.06 +/- 3.70) nmol/10(8) platelets] was decreased significantly as compared with normal controls [(28.39 +/- 4.45) nmol/10(8) platelets] (P < 0.01), and so did the NOS activity [(1.46 +/- 0.47) pmol/10(8) platelets] vs (1.81 +/- 0.50) pmol/10(8) platelets]. The transportation of L-Arg by hypercholesterolemia platelets also decreased significantly than that by normal controls. The Vmax in the former [(46.84 +/- 3.39) pmol x (10(7) platelets)(-1) x min(-1)] was significantly lower than that in the latter [(53.89 +/- 3.45) pmol x (10(7) platelets)(-1) x min(-1)]. There was no difference between the two groups in K(d) (P > 0.05). CONCLUSIONS: The activity of the L-arg/NO pathway in hypercholesterolemia platelets is decreased significantly as compared with normal controls, implying that it is probably one of the reasons for the hyperactivity of hypercholesterolemia platelets.

Adult↗

PubMed2000

Sequence and analysis of chromosome 1 of the plant Arabidopsis thaliana.

The genome of the flowering plant Arabidopsis thaliana has five chromosomes. Here we report the sequence of the largest, chromosome 1, in two contigs of around 14.2 and 14.6 megabases. The contigs extend from the telomeres to the centromeric borders, regions rich in transposons, retrotransposons and repetitive elements such as the 180-base-pair repeat. The chromosome represents 25% of the genome and contains about 6,850 open reading frames, 236 transfer RNAs (tRNAs) and 12 small nuclear RNAs. There are two clusters of tRNA genes at different places on the chromosome. One consists of 27 tRNA(Pro) genes and the other contains 27 tandem repeats of tRNA(Tyr)-tRNA(Tyr)-tRNA(Ser) genes. Chromosome 1 contains about 300 gene families with clustered duplications. There are also many repeat elements, representing 8% of the sequence.

Arabidopsis↗