Biomedical subjects

B Zheng

Publications and source records attributed to B Zheng.

At least 55 records · Page 3Linked to original sources

PubMed2001

Distinct tumour specificity and IL-7 requirements of CD56(-)and CD56(+) subsets of human gamma delta T cells.

gamma delta T cells are believed to recognize tissue injury caused by infections, tumours, as well as chemical and physical agents. The present study was carried out to study the feasibility of the ex vivo expansion of gamma delta T cells from healthy individuals, and to determine their functional capacity against tumours. We selectively expanded the peripheral gamma delta T cells of five donors against a myeloma cell line, XG-7. Under optimal conditions, the resulting bulk cultures comprised about 82% of the gamma delta T cells, more than 90% of which showed the T-cell receptor (TCR)-V gamma 9 delta 2 rearrangement. These gamma delta T-cell cultures exhibited TCR-gamma delta dependent cytotoxicity against different tumour cell lines including Molt-4, BJAB, Epstein-Barr virus (EBV) transformed lymphoid cell lines (LCL), and the nasopharyngeal carcinoma (NPC) cell lines, CNE2 and 915, in addition to the stimulator XG-7. By competitive cytotoxicity assays, the gamma delta T cells demonstrated recognition of at least three distinct target specificities expressed by Molt-4, CNE2 and LCL, respectively, which were related to that expressed by the stimulator XG-7 cells. The recognition of the specificity expressed by XG-7 and Molt-4 was further shown to require the participation of heat shock protein (HSP). The specificity expressed by CNE2 and 915 was preferentially recognized by the CD56 subset of gamma delta T cells, which could be sustained in the presence of interleukin (IL)-7. These results suggested that gamma delta T-cell immunity against tumour cell lines may be acquired in response to other types of tissue injury and, hence, implicates a role for their use in the prevention and treatment of tumours.

Burkitt Lymphoma↗

PubMed2001

Primary transanal rectosigmoidectomy for Hirschsprung's disease: Preliminary results in the initial 33 cases.

PURPOSE: The authors describe their newly developed technique-primary transanal rectosigmoidectomy for Hirschsprung's disease (HD) and its preliminary results in neonates and infants. METHODS: Thirty-four consecutive patients (26 boys) with biopsy-proven rectosigmoid HD, aged 18 days to 4 years, underwent this new procedure. Rectal mucosectomy started 1 to 1.5 cm posteriorly and 2 to 3 cm anteriorly proximal to the dentate line. The rectal muscular sleeve below the peritoneal reflection was resected to the level of the striated muscle complex, leaving a shorter muscular cuff, into which a partial internal sphincterotomy was made posteriorly. An oblique anastomosis was constructed between the pull-through ganglionic colon and the anus canal. RESULTS: The mean time for the operation was 160 minutes, and the average length of bowel resected was 29.5 cm (range, 12.5 to 41 cm). Two children (6.06%, 2 of 33) had 2 to 5 episodes of postoperative enterocolitis (EC). One was cured by rectal irrigation and dilation, and the another by Lynn's myectomy. Eighty-four percent of patients had 1 to 6 bowel movements per day during a 6- to 18-month follow-up period. CONCLUSIONS: Primary transanal rectosigmoidectomy for HD is logical and associated with excellent early results. A long-term follow-up is required to determine bowel functions. J Pediatr Surg 36:1816-1819.

Anal Canal↗

PubMed2001

The specialty of the treating physician affects the likelihood of tumor-free resection margins for basal cell carcinoma: results from a multi-institutional retrospective study.

BACKGROUND: Basal cell carcinoma (BCC) is the most common cutaneous malignancy. Surgical experience and physician specialty may affect the outcome quality of surgical excision of BCC. METHODS: We performed a multicenter retrospective study of BCC excisions submitted to the respective Departments of Pathology at 4 major university medical centers. Our outcome measure was presence of histologic evidence of tumor present in surgical margins of excision specimens (incomplete excision). Clinician experience was defined as the number of excisions that a clinician performed during the study interval. The analytic sample pool included 1459 tumors that met all inclusion and exclusion criteria. Analyses included univariate and multivariate techniques involving the entire sample and separate subsample analyses that excluded 2 outlying dermatologists. RESULTS: Tumor was present at the surgical margins in 243 (16.6%) of 1459 specimens. A patient's sex, age, and tumor size were not significantly related to the presence of tumor in the surgical margin. Physician experience did not demonstrate a significant difference either in the entire sample (P <.09) or in the subsample analysis (P >.30). Tumors of the head and neck were more likely to be incompletely excised than truncal tumors in all the analyses (P <.03). Compared with dermatologists, otolaryngologists (P <.02) and plastic surgeons (P <.008) were more likely to incompletely excise tumors; however, subsample analysis for plastic surgeons found only a trend toward significance (P <.10). Dermatologists and general surgeons did not differ in the likelihood of performing an incomplete excision (P >.4). CONCLUSION: The physician specialty may affect the quality of care in the surgical management of BCC.

Aged↗

PubMed2001

Muristerone A-induced nerve growth factor release from genetically engineered human dermal fibroblasts for peripheral nerve tissue engineering.

In this study, human dermal fibroblasts (hDFBs) were genetically modified to release human nerve growth factor (NGF) using an ecdysone-inducible system. NGF cDNA was inserted into the pIND vector and then hDFBs were cotransfected with pIND-NGF and pVgRXR. Muristerone A, an analog of ecdysone, was used as the inducing agent. NGF release from transfected hDFBs was assessed in vitro and in vivo. Transfected hDFBs in the presence of Muristerone A possessed a maximal in vitro release of 8.5 +/- 0.4 pg of NGF/mL per 10(3) cells, demonstrating significantly higher NGF levels compared to control hDFBs. The in vitro release rate curve for transfected hDFBs in the presence of Muristerone A exhibited a maximum of 5.1 +/- 0.2 ng NGF/10(6) cells/day. A PC-12 bioassay demonstrated that the in vitro NGF released is bioactive. When transfected hDFBs in the presence of Muristerone A were placed in vivo in nude rats, NGF levels reach 2074 +/- 257 pg/mL and 1620 +/- 132 pg/mL at 24 and 48 h, respectively. These levels were significantly higher than negative control and wound fluid levels. Results support further in vivo investigation of this molecular "on" switch for peripheral nerve regeneration.

Animals↗

PubMed2001

Dermal fibroblasts genetically engineered to release nerve growth factor.

Current surgical strategies for repair of critical nerves involves the transfer of normal donor nerve from an uninjured body location. One possible alternative to autogenous tissue replacement is the development of engineered constructs to replace those elements necessary for axonal proliferation. Delivery of growth factors is one strategy to enhance synthetic nerve constructs. Thus, this study focused on the delivery of nerve growth factor (NGF) by genetic engineering to begin approaching the microenvironment dictated, in part, by Schwann's cells. Rat dermal fibroblasts (DFBs) were modified genetically to release rat NGF. The reporter gene LacZ was used to assess the optimum nonviral transfection method commercially available before NGF transfection. FuGENE6 provided the optimum transfection efficiency (24% maximum, 20.1 +/- 1.9% 5-day average) as measured by beta-galactosidase catalytic activity. NGF release from transfected DFBs was assessed over a 3-day period. Compared with control (no transfection) DFBs and DFBs transfected with vector alone, DFBs transfected with an expression vector encoding rat beta-NGF demonstrated significantly (p < 0.05) higher levels of NGF, with a 3-day maximum of 111 pg NGF per milliliter. When normalized to cell number, NGF-transfected DFBs released 1.2 pg NGF per milliliter/10(3) cells. The NGF-transfected DFBs demonstrated a maximal NGF release rate at day 1 (1.2 ng NGF/10(6) cells per day), followed by a markedly lower, sustained release rate at days 2 and 3 (0.44 ng NGF/10(6) cells per day and 0.48 ng NGF/10(6) cells per day respectively). The release rate curves for control and vector-transfected DFBs also exhibited a maximal NGF release rate at day 1, but were followed by a decreasing release rate, potentially representing in vitro degradation of NGF present in fetal bovine serum. Although not first with the development of growth factor delivery through fibroblasts, these findings suggest that rat DFBs can be modified genetically to act like Schwann's cells to deliver NGF.

Animals↗

PubMed2001

Health behavior changes after colon cancer: a comparison of findings from face-to-face and on-line focus groups.

This qualitative study assessed the feasibility and comparability of findings from face-to-face versus on-line chat focus groups including 12 individuals affected by colon cancer. Discussion questions focused on issues of lifestyle (nutrition and exercise), cancer screening, and treatment. Despite demographic differences, the themes that emerged from the two types of groups were similar. On-line participants generally talked more about cancer treatment and advocacy issues and used support groups more frequently. The anonymity of on-line chat groups appeared to provide a more comfortable forum for some people to discuss sensitive personal health issues. As both methods provided similar results, researchers may wish to consider circumstances in which using chat-based focus groups may provide a feasible alternative to traditional face-to-face groups.

Colonic Neoplasms↗

PubMed2001

Chloroplast and mitochondrial proteases in Arabidopsis. A proposed nomenclature.

The identity and scope of chloroplast and mitochondrial proteases in higher plants has only started to become apparent in recent years. Biochemical and molecular studies suggested the existence of Clp, FtsH, and DegP proteases in chloroplasts, and a Lon protease in mitochondria, although currently the full extent of their role in organellar biogenesis and function remains poorly understood. Rapidly accumulating DNA sequence data, especially from Arabidopsis, has revealed that these proteolytic enzymes are found in plant cells in multiple isomeric forms. As a consequence, a systematic approach was taken to catalog all these isomers, to predict their intracellular location and putative processing sites, and to propose a standard nomenclature to avoid confusion and facilitate scientific communication. For the Clp protease most of the ClpP isomers are found in chloroplasts, whereas one is mitochondrial. Of the ATPase subunits, the one ClpD and two ClpC isomers are located in chloroplasts, whereas both ClpX isomers are present in mitochondria. Isomers of the Lon protease are predicted in both compartments, as are the different forms of FtsH protease. DegP, the least characterized protease in plant cells, has the most number of isomers and they are predicted to localize in several cell compartments. These predictions, along with the proposed nomenclature, will serve as a framework for future studies of all four families of proteases and their individual isomers.

Arabidopsis↗

PubMed2001

Trust in physicians and medical institutions: what is it, can it be measured, and does it matter?

Despite the profound and pervasive importance of trust in medical settings, there is no commonly shared understanding of what trust means, and little is known about what difference trust actually makes, what factors affect trust, and how trust relates to other similar attitudes and behaviors. To address this gap in understanding, the emerging theoretical, empirical, and public policy literature on trust in physicians and in medical institutions is reviewed and synthesized. Based on this review and additional research and analysis, a formal definition and conceptual model of trust is presented, with a review of the extent to which this model has been confirmed by empirical studies. This conceptual and empirical understanding has significance for ethics, law, and public policy.

Confidentiality↗

PubMed2001

Knowledge-based computer-aided detection of masses on digitized mammograms: a preliminary assessment.

The purpose of this work was to develop and evaluate a computer-aided detection (CAD) scheme for the improvement of mass identification on digitized mammograms using a knowledge-based approach. Three hundred pathologically verified masses and 300 negative, but suspicious, regions, as initially identified by a rule-based CAD scheme, were randomly selected from a large clinical database for development purposes. In addition, 500 different positive and 500 negative regions were used to test the scheme. This suspicious region pruning scheme includes a learning process to establish a knowledge base that is then used to determine whether a previously identified suspicious region is likely to depict a true mass. This is accomplished by quantitatively characterizing the set of known masses, measuring "similarity" between a suspicious region and a "known" mass, then deriving a composite "likelihood" measure based on all "known" masses to determine the state of the suspicious region. To assess the performance of this method, receiver-operating characteristic (ROC) analyses were employed. Using a leave-one-out validation method with the development set of 600 regions, the knowledge-based CAD scheme achieved an area under the ROC curve of 0.83. Fifty-one percent of the previously identified false-positive regions were eliminated, while maintaining 90% sensitivity. During testing of the 1,000 independent regions, an area under the ROC curve as high as 0.80 was achieved. Knowledge-based approaches can yield a significant reduction in false-positive detections while maintaining reasonable sensitivity. This approach has the potential of improving the performance of other rule-based CAD schemes.

Breast Neoplasms↗

PubMed2001

Performance gain in computer-assisted detection schemes by averaging scores generated from artificial neural networks with adaptive filtering.

The authors investigated a new method to optimize artificial neural networks (ANNs) with adaptive filtering used in computer-assisted detection schemes in digitized mammograms and to assess performance changes when averaging classification scores from three sets of optimized schemes. Two independent training and testing image databases involving 978 and 830 digitized mammograms, respectively, were used in this study. In the training data set, initial filtering and subtraction resulted in the identification of 592 mass regions and 3790 suspicious, but actually negative regions. These regions (including both true-positive and negative regions) were segmented into three subsets three times based on the calculation of the values of three features as segmentation indices. The indices were "mass" size multiplied by their digital value contrast, conspicuity, and circularity. Nine ANN-based classifiers were separately optimized using a genetic algorithm for each subset of regions. Each region was assigned three classification scores after applying the three adaptive ANNs. The performance gain of the CAD scheme after averaging the three scores for each suspicious region was tested using an independent data set and a ROC methodology. The experimental results showed that the areas under ROC curves (Az) for the testing database using three sets of optimized ANNs individually were 0.84+/-0.01, 0.83+/-0.01, and 0.84+/-0.01, respectively. The between-index correlations of three A values were 0.013, -0.007, and 0.086. Similar to averaging diagnostic ratings from independent observers, by averaging three ANN-generated scores for each testing region, the performance of the CAD scheme was significantly improved (p<0.001) with Az value of 0.95+/-0.01.

Algorithms↗

PubMed2001

Soft-copy mammographic readings with different computer-assisted detection cuing environments: preliminary findings.

PURPOSE: To assess the performance of radiologists in the detection of masses and microcalcification clusters on digitized mammograms by using different computer-assisted detection (CAD) cuing environments. MATERIALS AND METHODS: Two hundred nine digitized mammograms depicting 57 verified masses and 38 microcalcification clusters in 85 positive and 35 negative cases were interpreted independently by seven radiologists using five display modes. Except for the first mode, for which no CAD results were provided, suspicious regions identified with a CAD scheme were cued in all the other modes by using a combination of two cuing sensitivities (90% and 50%) and two false-positive rates (0.5 and 2.0 per image). A receiver operating characteristic study was performed by using soft-copy images. RESULTS: CAD cuing at 90% sensitivity and a rate of 0.5 false-positive region per image improved observer performance levels significantly (P < .01). As accuracy of CAD cuing decreased so did observer performances (P < .01). Cuing specificity affected mass detection more significantly, while cuing sensitivity affected detection of microcalcification clusters more significantly (P < .01). Reduction of cuing sensitivity and specificity significantly increased false-negative rates in noncued areas (P < .05). Trends were consistent for all observers. CONCLUSION: CAD systems have the potential to significantly improve diagnostic performance in mammography. However, poorly performing schemes could adversely affect observer performance in both cued and noncued areas.

Area Under Curve↗

PubMed2001

MPer1 and mper2 are essential for normal resetting of the circadian clock.

Mammalian Per1 and Per2 genes are involved in the mechanism of the circadian clock and are inducible by light. A light pulse can evoke a change in the onset of wheel-running activity in mice by shifting the onset of activity to earlier times (phase advance) or later times (phase delays) thereby advancing or delaying the clock (clock resetting). To assess the role of mouse Per (mPer) genes in circadian clock resetting, mice carrying mutant mPer1 or mPer2 genes were tested for responses to a light pulse at ZT 14 and ZT 22, respectively. The authors found that mPer1 mutants did not advance and mPer2 mutants did not delay the clock. They conclude that the mammalian Per genes are not only light-responsive components of the circadian oscillator but also are involved in resetting of the circadian clock.

Animals↗

PubMed2001

[The distribution and natural degradation of cyanide in goldmine waste-solid and polluted soil].

The farmland and river were seriously polluted by cyanide because one goldmine tailing dam collapsed in 1995. 3 and 4 years after the accident, the cyanide distribution in the polluted farmland and the abandoned tailing dam was studied. The results indicated that natural degradation of cyanide in soil section was slower than in natural water body. The cyanide transference in soil section was similar to freely soluble salts. In arid and semiarid area, cyanide can be highly enriched in the salt shell which content degrading 4 years even higher than the fresh tailing slurry. One side the viscidity layer in the soil section can partly prevent cyanide transference to groundwater, on the other side the result can cause the cyanide highly enrich in the viscidity layer. According to character of cyanide natural degradation in soil the measurement of prevention and cure soil pollution by goldmine tailing dam collapsing was brought forward.

Cyanides↗

PubMed2001

Aortic and mitral valve replacement with retrograde perfusion in the beating heart.

OBJECTIVE: To estimate the value of aortic valves and combined mitral valve replacement with retrograde perfusion in beating hearts. METHODS: Continuous retrograde coronary sinus perfusion with beating hearts was used in 83 patients undergoing aortic valve or aortic valve combined with mitral valve replacement, without application of cardioplegia. After aortic valve replacement, the retrograde perfusion was changed to antegrade perfusion for mitral valve replacement or correction of the other deformities (group A). Cold blood cardioplegia solution (15 degrees C) was infused at intervals in 20 cases (group B). The following parameters were tested: lactate, ET, CTn-T and MDA in blood; myocardial ultra-structure; and cardiac rhythm and cardiac output (CO). RESULTS: All biochemical values increased after cardiopulmonary bypass (P < 0.05-0.01). Empty and beating heart sinus rhythm was maintained in group A. Myocardial ultrastructure did not change significantly. The pump was stopped smoothly as the surgical procedure finished. No postoperative low cardiac output syndrome or arrhythmia was observed. Eight-one patients recovered smoothly, two died from renal failure or infective shock. When the pump stopped, all patients in group B were supported by 5-10 micrograms.kg-1.min-1 dopamine. Transient pacing was used in 9 patients. One patient died from low cardiac output syndrome. CONCLUSION: This method is a good myocardial protection which simulates physiologic status. It is applicable to aortic valve and combined mitral valve replacement of patients with large heart or heart failure and long time aortic cross-clamping. Ideal clinical effect can be achieved.

Adolescent↗

PubMed2001

[A randomized, controlled clinical trial of meropenem and imipenem/cilastatin in the treatment of acute bacterial infections].

OBJECTIVE: Meropenem is a new carbapenem antibiotic developed by Sumitomo Pharmaceuticals and shown to resist degradation by renal dehydropeptidase I (DPH-I), an enzyme which exists chiefly in the kidneys and decomposes carbapenem antibiotics. It has a powerful antibacterial activity with broad antibacterial spectrum. The objective of the study is to evaluate the efficacy and safety of meropenem. METHODS: A randomized, open-label, controlled study was conducted for treating patients with bacterial infections. A total of 112 hospitalized patients were enrolled in the study. 55 patients received meropenem 500 mg every 12 hours (or 1g every 12 hours if necessary) and 57 patients received imipenem/cilastatin 500 mg/500 mg every 12 hours (or 1g/1g every 12 hours if necessary) intravenously. The duration of treatment was 7-14 days in both groups. RESULTS: 42 of the 55 cases receiving meropenem and 41 of the 57 cases receiving imipenem/cilastatin were assessable for clinical efficacy. The overall efficacy rate was 88.1%(37/42) for the meropenem group and 85.4%(35/41) for the imipenem/cilastatin group, whereas the bacterial eradication rate was 81.1%(30/37) and 84.2%(32/38), respectively. 47(69.1%) of 68 strains isolated from patients produced beta-lactamase. Adverse drug reaction was evaluated in 44 cases of the meropenem group and 41 cases of the imipenem/cilastatin group. The adverse drug reaction rate was 13.6%(6/44) and 12.2%(5/41), respectively. The results showed that there were no statistical differences between these two groups (P > 0.05). CONCLUSION: Meropenem and imipenem/cilastatin were effective and safe for the treatment of lower respiratory tract infections and urinary tract infections and other infections caused by beta-lactamase-producing strains.

Cilastatin↗

PubMed2001

[Production of HPV 16 major capsid protein L1 with baculovirus expression system].

BACKGROUND: To obtain human papillomavirus type 16(HPV 16) major capsid protein L1 with baculovirus expression system. METHODS: Using pFb1 as a vector,a recombinant baculovirus expressing plasmid,which contains HPV16L1 gene sequence,was generated. The constructed virus was infected into an insect cell line Sf9. RESULTS: After incubating at 27 degrees for 72 hours, the infected cells were collected and total cellular poteins were extracted. SDS-PAGE assay revealed a roughly 56 000 expressed protein and Western blot confirmed that the expressed protein arose from HPV16L1. CONCLUSIONS: HPV16 later protein L1 could be efficiently expressed with baculovirus expression system,and the expressed L1 protein remains to have good immunoreactivity. This study may supply a basic work for preparing virus-like particle and prophylactic HPV subunit vaccines.

Animals↗

PubMed2001

[Effect of Puerarin on platelet activating factors CD63 and CD62P, plasminogen activator inhibitor and C-reactive protein in patients with unstable angia pectoris].

OBJECTIVE: To explore the action of platelet surface activity protein (platelet granule membrane protein CD63 and lysosome membrane protein CD62P), plasminogen activator inhibitor (PAI-1) and C-reactive protein (C-RP) in occurrence and development of unstable angina pectoris (UAP), and the effect of Puerarin on them. METHODS: Patients with UAP were randomly divided into the treated group (32 cases, treated with Puerarin) and the control group (27 cases, treated with Ticlid), the therapeutic course was 4 weeks for both groups. Changes of CD63, CD62P, PAI-1 and C-RP before and after treatment were observed. RESULTS: The levels of CD63, CD62P, PAI-1 and C-RP were higher in UAP patients than those in normal subjects and in the patients with stable angina pectoris (P < 0.05 or P < 0.01). These parameters were increased along with the aggravating of patients in Braunwald's degree. After 4-week treatment, the above-mentioned parameters lowered in both groups (P < 0.05 or P < 0.01), and comparison between the two groups showed no significant difference statistically. CONCLUSION: Platelet activation, plasminogen activator and C-RP play important roles in the occurrence and development of UAP. The obvious effect of Puerarin in anti-platelet activation, improving plasminogen activator and relieving inflammatory reaction was of great importance in preventing the occurrence and development of acute coronary syndrome clinically.

Adult↗

PubMed2000

Speciation of key arsenic metabolic intermediates in human urine.

Biomethylation is the major human metabolic pathway for inorganic arsenic, and the speciation of arsenic metabolites is essential to a better understanding of arsenic metabolism and health effects. Here we describe a technique for the speciation of arsenic in human urine and demonstrate its application to the discovery of key arsenic metabolic intermediates, monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII), in human urine. The study provides a direct evidence in support of the proposed arsenic methylation pathway in the human. The finding of MMAIII and DMAIII in human urine, along with recent studies showing the high toxicity of these arsenicals, suggests that the usual belief of arsenic detoxification by methylation needs to be reconsidered. The arsenic speciation technique is based on ion pair chromatographic separation of arsenic species on a 3-micron particle size column at 50 degrees C followed by hydride generation atomic fluorescence detection. Speciation of MMAIII, DMAIII, arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV) in urine samples is complete in 6 min with detection limits of 0.5-2 micrograms/L. There is no need for any sample pretreatment. The capability of rapid analysis of trace levels of arsenic species, which resulted in the findings of the key metabolic intermediates, makes the technique useful for routine arsenic speciation analysis required for toxicological and epidemiological studies.

Arsenic↗