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Biomedical subjects

K Shen

Publications and source records attributed to K Shen.

At least 19 recordsLinked to original sources
PubMed2006

Phenotypic characterization of Streptococcus pneumoniae biofilm development.

Streptococcus pneumoniae is among the most common pathogens associated with chronic otitis media with effusion, which has been hypothesized to be a biofilm disease. S. pneumoniae has been shown to form biofilms, however, little is known about the developmental process, the architecture, and the changes that occur upon biofilm development. In the current study we made use of a continuous-culture biofilm system to characterize biofilm development of 14 different S. pneumoniae strains representing at least 10 unique serotypes. The biofilm development process was found to occur in three distinct stages, including initial attachment, cluster formation, and biofilm maturation. While all 14 pneumococcal strains displayed similar developmental stages, the mature biofilm architecture differed significantly among the serotypes tested. Overall, three biofilm architectural groups were detected based on biomass, biofilm thickness, and cluster size. The biofilm viable cell counts and total protein concentration increased steadily over the course of biofilm development, reaching approximately 8 x 10(8) cells and approximately 15 mg of protein per biofilm after 9 days of biofilm growth. Proteomic analysis confirmed the presence of distinct biofilm developmental stages by the detection of multiple phenotypes over the course of biofilm development. The biofilm development process was found to correlate not only with differential production of proteins but also with a dramatic increase in the number of detectable proteins, indicating that biofilm formation by S. pneumoniae may be a far more complex process than previously anticipated. Protein identification revealed that proteins involved in virulence, adhesion, and resistance were more abundant under biofilm growth conditions. A possible role of the identified proteins in biofilm formation is discussed.

Bacterial Proteins↗
PubMed2005

NMR spectroscopy of hydrogen adsorption on single-walled carbon nanotubes after exposure to high pressure.

Hydrogen storage properties of single-walled carbon nanotubes (CNTs) after exposure to a pressure of 14.3 MPa are studied by (1)H nuclear magnetic resonance spectroscopy. The nanotubes were carefully pre-characterized using inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM), and Raman spectroscopy. We have shown previously that at ambient temperature in the pressure range from 0 to 1.5 MPa, hydrogen adsorption is fast and reversible and must be described as physisorption. However, exposure to a much higher pressure (14.3 MPa) of hydrogen leads to slower desorption kinetics where longer exposure causes greater hydrogen uptake. Our data suggest that interstitial sites and the tube interior may be identified as these strong adsorption sites.

Adsorption↗
PubMed2004

Media remodeling--the result of stent induced media necrosis and repair.

BACKGROUND: Stents have been introduced clinically to help maintaining the patency of the vascular lumen after balloon angioplasty. To ensure a sufficient lumen of the stented vessel, oversized stents are frequently used. However especially deployment of oversized stents may lead to mechanical injury of the intima and media of the vessel wall. The aim of the study was to characterize the vascular lesions and repair processes within the first 4 weeks after implantation of oversized stents in the rabbit carotid artery and thereby contribute to the understanding of vascular remodeling during stent implantation. METHODS: Oversized stents were implanted in the carotid artery of Chinchilla rabbits. Rabbits were sacrificed 3, 7, 14, and 28 days after stent implantation and a detailed histologic and immunohistochemical analysis was performed. RESULTS: The carotid artery was expanded by a factor of 1.3-1.5, leading to a constant dilatation of the vessel. The struts were deeply impressed in the vessel wall, resulting in a disruption of the intima, thrombus formation, media compression and segmental media necrosis. The necrotic media was repopulated by smooth muscle cells by day 7. In contrast to the intima lesions, necrotic areas of the media were not invaded by an inflammatory infiltrate. Formation of neointima, characterized by a confluent layer of endothelial cells and deposition collagenfibers started in close vicinity of the struts. CONCLUSIONS: Being part of a high-pressure system, the arterial vessel apparently adapts to constant dilatation. Deployment of oversized stents caused intima disruption, media necrosis of varying degree and constant dilatation of the vessel wall. Necrosis and repopulation of smooth muscle cells of the media took place within the first 4 weeks, leading to the speculation whether the repopulating SMC are more resistant to the constant pressure.

Animals↗
PubMed2003

Adoptive transfer of donor-derived immunity by liver transplantation: a potential avenue to prevent hepatitis B virus reinfection.

Immunity to hepatitis B has been successfully transferred by bone marrow transplantation, but has also occurred after liver transplantation (LTx). This study was designed to analyse the influence of alloreactivity and immunosuppression, on the efficacy of adoptive immune transfer to hepatitis B by liver transplantation. Orthotopic LTx (n = 34) were performed in three rat strain combinations representing different genetic constellations. Donors had been vaccinated twice with recombinant hepatitis B surface antigen while recipients were unimmunized. Half of the allogeneic recipients were immunosuppressed with cyclosporin A. All animals were monitored weekly for the presence of anti-hepatitis B surface antibodies (anti-HBs). Effective anti-HBs titres were detected in 85% (29/34) of liver recipients and lasted from 2 to 10 weeks. Donor titre above >15 000 mIU/mL ensured a 100% seroconversion rate in the recipients. The maximal anti-HBs titre in recipients represented 0.06% approximately 0.76% of the donor titre. Rejection reduced the adoptive immune transfer, which was protected by immunosuppression. These observations suggest that transfer of functionally active donor lymphocytes, deriving from the graft, contributed to the donor-derived immune response in the recipient. Further studies to augment the donor-derived immune response are warranted to ensure a therapeutic effect for the recipient at risk of reinfection.

Animals↗
PubMed2001

Acquisition of a specific and potent PTP1B inhibitor from a novel combinatorial library and screening procedure.

Protein-tyrosine phosphatases (PTPases) form a large family of enzymes that serve as key regulatory components in signal transduction pathways. Defective or inappropriate regulation of PTPase activity leads to aberrant tyrosine phosphorylation, which contributes to the development of many human diseases including cancers and diabetes. For example, recent gene knockout studies in mice identify PTP1B as a promising target for anti-diabetes/obesity drug discovery. Thus, there is intense interest in obtaining specific and potent PTPase inhibitors for biological studies and pharmacological development. However, given the highly conserved nature of the PTPase active site, it is unclear whether selectivity in PTPase inhibition can be achieved. We describe a combinatorial approach that is designed to target both the active site and a unique peripheral site in PTP1B. Compounds that can simultaneously associate with both sites are expected to exhibit enhanced affinity and specificity. We also describe a novel affinity-based high-throughput assay procedure that can be used for PTPase inhibitor screening. The combinatorial library/high-throughput screen protocols furnished a small molecule PTP1B inhibitor that is both potent (K(i) = 2.4 nm) and selective (little or no activity against a panel of phosphatases including Yersinia PTPase, SHP1, SHP2, LAR, HePTP, PTPalpha, CD45, VHR, MKP3, Cdc25A, Stp1, and PP2C). These results demonstrate that it is possible to acquire potent, yet highly selective inhibitors for individual members of the large PTPase family of enzymes.

Animals↗
PubMed2001

Controlling spatiotemporal chaos via phase space compression.

We present a simple and effective method for controlling spatiotemporal chaos (STC) via phase space compression, by compressing the evolution orbit of the chaotic attractor. In numerical simulations, we obtain global and local control in coupled map lattice (CML) systems by the same phase space compression in different situations, and find that the functional relationship of control results to control parameters in a certain region is the same as the local dynamics expression of the CML. According to the control equation, using different phase space compressions we successfully control a CML exhibiting STC into various desired stable states.

Journal Article↗
PubMed2001

[Relationship of vitamin D receptor polymorphism with breast cancer].

OBJECTIVE: To detect the association between vitamin D receptor polymorphism and breast cancer. METHODS: Polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) method was used. Two restriction fragment length polymorphisms in the 3'region of vitamin D receptor (VDR) gene, Taq I and Apa I, were tested for association with breast cancer risk in 86 females with breast cancer and 134 healthy female controls. RESULTS: Allele frequencies of the 3'Taq I polymorphism showed a significant association (P=0.0004, OR:5.39,CI:1.81-17.20). The further study of genotype found the association of Tt, tt with breast cancer. The haplotype analysis of Apa I and Taq I showed a linkage disequilibrium between t-allele and A-allele. The frequency of tA haplotype was higher in breast cancer patients than in controls (P=0.001), indicating that tA haplotype is associated with breast cancer. The alleles and haplotype of the two loci had not any difference among the clinical subgroups. CONCLUSION: There is association between vitamin D receptor polymorphism and breast cancer.

Adult↗
PubMed2001

[The impact of calpain-10 gene combined-SNP variation on type 2 diabetes mellitus and its related metabolic traits].

OBJECTIVE: To investigate the impact of calpain-10 gene (CAPN-10) combined single nucleotide polymorphism (SNP) variation on type 2 diabetes mellitus (T2DM) and its related clinical metabolic traits in Chinese. METHODS: The study population consisted of 268 Chinese residents in Shanghai. Among them, 144 were subjects with normal glucose tolerance (NGT) and 124, with T2DM. Plasma glucose (PG), insulin (INS), c-peptide (CP) and free fatty acids (FFA) levels were measured at fasting and 30, 60, 120, and 180 minutes after oral 75 g glucose challenge. The islet beta-cell insulin secretion and tissue insulin sensitivity were assessed. CAPN-10 UCSNP44,-43,-19 and -63 were genotyped. RESULTS: (1) In Chinese NGT subjects, the major allele of UCSNP-44 was allele T (frequency=91%), of UCSNP43 was G(89%), of UCSNP-19 was I (3 repeats of a 32 bp sequence) (67%) and of UCSNP-63 was C allele (79%). Significant differences were observed in comparison of these allele frequencies in Chinese to those in other ethnic groups reported in the literature. (2) 14 genotype combinations of these four SNPs were observed in Chinese NGT subjects. 69% of the NGT population was composed of four genotype combinations, in the order of UCSNP44,-43,-19 and -63, i.e., combination A:TT-GG-DI-CC(haplotype combination was 1121/1111) (frequency=10%), combination B:TT-GA-II-CC(1121/1221)(10%), combination C:TT-GG-II-CC(1121/1121)(26%) and combination D:TT-GG-DI-CT(1121/1112)(22%).(3) The frequencies of the above mentioned SNP in single or in combinations were not different significantly between NGT and T2DM groups. (4) The variation of clinical metabolic parameter levels shifted from completely normal towards abnormal glucose intolerance among genotype combination subgroups. In comparison between combination A and combination D, subjects in the former subgroups had: higher PG levels with delayed peak after glucose challenge; less and lower decrement of FFA levels after challenge with no rising in late stage; higher insulin levels with delayed peak after challenge; and the tendency of decreased insulin sensitivity. More than half of the comparisons remained statistically significant after adjusted with age, gender, body mass index and waist circumference. CONCLUSION: The variation of calpain-10 gene has impact on the variation of clinical metabolic parameter levels related to type 2 diabetes mellitus. Such impact depends upon the haplotypes as well as the haplotype combination of calpain-10 gene variations.

Alleles↗
PubMed2001

[Treatment of childhood genital malignancies].

OBJECTIVE: To present the clinical profile and the result of treatment in childhood genital malignancies. METHODS: Twenty seven childhood patients (< 12 years) with genital malignancies diagnosed and treated in Peking Union Medical College hospital were analyzed retrospectively focusing on the clinical characteristics and outcome of the treatment. RESULTS: Patients ranged in age from 2 to 12 years with mean 6.5 years at diagnosis. Of the 27 patients, 23 had ovarian malignancies including 21 (77.8%) germ cell tumor. Four of the patients had extragonadal tumors with 2 endodermal sinus tumor of the vagina, and 2 embryonic rhabdomysarcoma. In ovarian malignancies, abdominal mass and abdominal pain were main clinical features accounting for 77.8% and 74.1% respectively. In vaginal malignancies, vaginal bleeding and polypoid tumor of the vagina were important clinical manifestations. 91.3% (21/23) of the patients underwent only unilateral salpingo-oophorectomy with preservation of contralateral ovary and the uterus. Childhood genital malignancies were very sensitive to the chemotherapy. Postoperative vincristine, actinomycine, cyclophosphamide (VAC) or cisplatine, vincristine, blyomycine (PVB) chemotherapy was individualized according to the tumor site, International Federation of Gynecology and obstetrics stage and histopathology. Survival rate in our series was 71.4% during the follow-up time (mean 47.4 months). CONCLUSIONS: Malignant germ cell tumor of the ovary is the most common tumor in the childhood genital malignancies. Principle of primary surgery is preservation of fertility and chemotherapy is also considered as a very important treatment modality.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

[A cross-sectional study on the promotion and execution of "the practiced guidelines for the management of common malignant gynecological tumors"].

OBJECTIVE: To evaluate the promotion and execution of "the practice guidelines for the management of common malignant gynecological tumors (draft)" (guidelines). METHODS: Cross sectional study was applied. All obstetricians and gynecologists (Obs/Gyns) who attended the Chinese Medical Association's Senior Workshop for Department Chairmen of Obstetrics and Gynecology were included. RESULTS: Three hundred and fifty Obs/Gyns were inquired, while two hundred and eighty-one questionnaires were available. Ninety percent (253/281) of Obs/Gyns declared that they had read the guidelines, and 96.4% (271/281) of them thought it necessary to establish the guidelines. In those Obs/Gyns who read the guidelines, 87.7% (222/253) of them managed gynecological tumors according to the guidelines. In those who did not read the guidelines, most were obstetricians or worked in special hospitals, while all gynecological oncologists read the guidelines. In addition, there were still many suggestions on the guidelines. CONCLUSION: The guidelines has been playing a role in the management of common malignant gynecological tumors and need to be revised regularly.

Cross-Sectional Studies↗
PubMed2001

[Evaluation of cervical conization in diagnosis and management of cervical intraepithelial neoplasia].

OBJECTIVE: To determine whether cervical conization can be instead of colposcopic multiple biopsies and to evaluate the clinical value of cervical conization in diagnosis and management of cervical intraepithelial neoplasia. METHODS: Fifty four patients with cervical intraepithelial neoplasia (CIN) diagnosed and treated at Peking Union Medical College hospital were retrospectively analyzed focusing on the comparative study in pathology between cerical conization and colposcopic multiple biopsies. RESULTS: Of the 54 patients, there was a correlation in pathology between cervical conization and colposcopic multiple biopsies in 22 cases (40.7%), but there was not much correspondence between cervical conization and colposcopic multiple biopsies in 32 cases (59.3%). In 31 cases conization performed for ruling out invasive cancer, there was a correlation in pathology between cervical conization and colposcopic multiple biopsies in only 13 cases (41.9%). After conization radical hysterectomy was performed in 2 cases (3.7%) because of early invasive carcinoma and simple hysterectomy was performed in 13 cases (24.1%) because of CINIII involved the gland and microinvasive carcinoma of the cervix. 39 cases (73.2%) were closely followed-up postoperatively with preservation of fertility. During the mean follow-up time of 18.3 months, no cytology abnormality was detected and 3 patients had pregnancy and delivery. Postoperative hemorrhage was main side effect for conization. CONCLUSIONS: Cervical conization plays a very important role in diagnosis and treatment of CIN and it can not be instead of colposcopic multiple biopsies. Cervical conization is a good choice for patient with CINIII and desired childbearing.

Adult↗
PubMed2001

[Loop electrosurgical excision procedure: a valuable method for the treatment of cervical intraepithelial neoplasia].

OBJECTIVE: To determine the effectiveness and safety of loop electrosurgical excision procedure (LEEP) for the management of cervical intraepithelial neoplasia (CIN) and the significance of positive margins in cervical cone biopsy specimens with the relationship of prognosis. METHODS: LEEP under local anesthesia and colposcopic guidance was performed in an outpatient of colposcopic clinic. Records of 135 patients treated between Feb 1992 and Jul 1999 were reviewed prospectively. RESULTS: The median age of patients in this study was 42 years (range 18-67 years), parity 2.2 times (range 0-8 times). High-grade squamous intraepithelial lesion (HGSIL) accounted for majority of diagnosis according to pap smear (65.9%) and colposcopy (75.6%) respectively. The results of LEEP demonstrated negative histology in 7 patients (5.2%), human papilloma virus (HPV) infection in 2 patients (1.5%), CINI in 15 patients (11.1%), HGSIL in 108 patients (80.0%) which including 20 patients (14.8%) of CINII, 88 patients (65.2%) of CINIII, microinvasion in 3 patients (2.2%). Clear resection margin of lesion in cervix was noted in 78 (57.8%) patients. Unclear margins were appeared in 57 (42.2%) patients including 21 cases (15.6%) of resection margin positive and 36 cases(26.7%) of resection margin undetermined. HGSIL accounted for the majority (54 cases, 94.7%) in this kind of patients. The residual CIN occurred in 1 patient (4.8%) with the resection margin positive and 3 patients(8.3%) with the resection margin undetermined respectively. In 2 patients (2.6%) with the resection margin clear. Recurrence CIN occurred in 1 patient (4.8%) with the resection margin positive and 2 patients (5.6%) with the resection margin undetermined respectively, none of the patients (0.0%) with the resection margin clear. The overall cure rate in this study was 93.3% after first LEEP done. The residual CIN was identified in 6 (4.4%) patients. The recurrence CIN occurred in 3 (2.2%) patients. Complications of LEEP occurred in 14.1% (19/135) patients in this study. CONCLUSIONS: LEEP is a kind of effective and safe method for the treatment of cervical intraepithelial neoplasia. The status of resection margin should be concerned. Margin involvement of specimen is the risk factor for residual and recurrence of CIN.

Adolescent↗
PubMed2001

[Effect of a risk of malignancy index in preoperative diagnosis of ovarian cancer].

OBJECTIVE: To evaluate the ability of a risk of malignancy index (RMI), based on a serum CA125 level, ultrasound findings and menopausal status, to discriminate a benign from a malignant pelvic mass. METHODS: One hundred and forty women with a pelvic mass, 30 years or older, admitted between January 1998 and June 1999, were studied. The sensitivity, specificity and positive predictive value of serum CA125 level, ultrasound findings and the menopausal status separately and combined into the RMI, to diagnose ovarian cancer. RESULTS: RMI was more accurate than any individual criterion in diagnosing cancer. Using a RMI cut-off level of 200 to indicate malignancy, the RMI derived from this data set gave a sensitivity of 87.3%, specificity of 84.4%, and positive predictive value of 82.1%. CONCLUSIONS: RMI is able to correctly discriminate between malignant and benign pelvic mass. It can be introduced easily into clinical practice to facilitate the selection of patients for primary surgery.

Adult↗
PubMed2001

Early diagnosis and monitoring of active HCMV infection in children with systemic lupus erythematosus.

OBJECTIVE: To investigate the prevalence and features of active human cytomegalovirus (HCMV) infection in children with systemic lupus erythematosus (SLE) and evaluate the diagnostic value of the HCMV using antigenemia assay, serum polymerase chain reaction (PCR) and serology test. METHODS: Twenty-one SLE children undergoing immunosuppressive therapy were enrolled in this study. Immunofluorescence assay, PCR and serology tests were used to determine HCMV pp65 and p72 antigens in leukocytes, HCMV DNA in sera, and HCMV specific IgM and IgG antibodies, respectively. As a control group, twenty-one immunocompetent children with skeletal malformation were involved in this study. Statistical analysis was performed using Chi-square test or Fisher's exact test (Systat, USA), P values less than 0.05 were considered significant. RESULTS: Active HCMV infection was diagnosed in 28.6% (6/21) of SLE patients, with none in the control group; the difference between the two groups was significant (P = 0.027). Two out of 6 SLE patients developed active HCMV infection before immunosuppressive therapy and the remaining 4 patients developed SLE after immunosuppressive therapy. Among the 21 SLE children, HCMV pp65 antigenemia was detected in 5 patients, p72 antigenemia in 3 patients, serum HCMV DNA in 9 patients, serum HCMV-specific IgM in 2 patients, and IgG in 19 patients. The sensitivity and specificity for diagnosis of active HCMV infection were 83.3% and 100%, respectively for pp65 antigenemia; 50% and 100% for p72 antigenemia; 100% and 80% for serum PCR; 33.3% and 100% for HCMV IgM serology; 50% and 100% for HCMV IgG serology. CONCLUSIONS: Compared with the control group, active HCMV infection is much more frequent in SLE children, and can occur before treatment with immunosuppressive agents, but most often occur after immunosuppressive therapy. In comparison with the other techniques used in this study, the pp65 antigenemia assay seems to be a better method for the early diagnosis and monitoring of active HCMV infection in children with SLE.

Adolescent↗
PubMed2001

[Determination of trace iodine based on kinetic-spectrophotometry with malachite green-chloramine T system].

In this paper, a new kinetic-spectrophotometric method for the determination of trace amount of iodine has been proposed. It is based on the iodine catalysed the reaction of malachite green oxidized by chloramine T in hydrochloric acid medium. The method is sensitive, simple and with good selectivity. The linear range of determination of iodine is 0-48 micrograms.L-1, the detection limit is 4.9 x 10(-10) g.mL-1. The method has been used for the determination of trace amount of iodine in food with satisfactory results.

Chloramines↗