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Biomedical subjects

H Cheng

Publications and source records attributed to H Cheng.

At least 19 recordsLinked to original sources
PubMed2007

Decision analysis model of incisional hernia after open abdominal surgery.

BACKGROUND: The incidence rate of incisional hernias after open surgery has been reported to be higher than that of port site hernias after laparoscopic surgery. No studies have compared the costs for the health care system in treating those two types of hernia. METHODS: A systematic review was conducted to obtain the baseline data, and a decision analysis model was created to simulate the occurrence and recurrence of incisional and port site hernias. RESULTS: The overall risk of having incisional hernias was eight-times higher than that of having port site hernias (7.4% vs 0.9%). A cost savings of 93 British Pound per patient can be generated for the health care system in the UK. Similar results were obtained for Germany, Italy and France. CONCLUSIONS: The additional treatment costs for incisional hernia should be taken into account when the costs of a surgery performed by open approach are compared with by laparoscopy.

Cost Savings↗
PubMed2006

Cancer incidence among semiconductor and electronic storage device workers.

AIMS: To evaluate cancer incidence among workers at two facilities in the USA that made semiconductors and electronic storage devices. METHODS: 89 054 men and women employed by International Business Machines (IBM) were included in the study. We compared employees' incidence rates with general population rates and examined incidence patterns by facility, duration of employment, time since first employment, manufacturing era, potential for exposure to workplace environments other than offices and work activity. RESULTS: For employees at the semiconductor manufacturing facility, the standardised incidence ratio (SIR) for all cancers combined was 81 (1541 observed cases, 95% confidence interval (CI) 77 to 85) and for those at the storage device manufacturing facility the SIR was 87 (1319 observed cases, 95% CI 82 to 92). The subgroups of employees with > or =15 years since hiring and > or =5 years worked had 6-16% fewer total incidents than expected. SIRs were increased for several cancers in certain employee subgroups, but analyses of incidence patterns by potential exposure and by years spent and time since starting in specific work activities did not clearly indicate that the excesses were due to occupational exposure. CONCLUSIONS: This study did not provide strong or consistent evidence of causal associations with employment factors. Data on employees with long potential induction time and many years worked were limited. Further follow-up will allow a more informative analysis of cancer incidence that might be plausibly related to workplace exposures in the cohort.

Adult↗
PubMed2006

Synthesis, characterisation, activities, cell uptake and DNA binding of a trinuclear complex: [[trans-PtCl(NH3)]2mu-[trans-Pd(NH3)(2-hydroxypyridine)-(H2)N(CH2)6NH2)2]Cl4.

The trinuclear complex: [[trans-PtCl(NH3)](2)mu-[trans-Pd(NH(3))(2-hydroxypyridine)-(H(2)N(CH(2))(6)NH(2))(2)]Cl(4) (code named CH25) has been synthesized and characterized. The activity of the compound against human ovarian cancer cell lines: A2780, A2780 cisR and A2780 ZD0473R, cell up take, level of binding with DNA and nature of its interaction with pBR322 plasmid DNA have been determined. The compound is found to exhibit significant anticancer activity against the cell lines-about 45 times as active as cisplatin against A2780 cell line, about 76 times as active as cisplatin against A2780(cisR) cell line and about seven times as active as cisplatin against A2780cell line. The higher activity of CH25 suggests that the compound is able to overcome multiple mechanisms of resistance operating in A2780(cisR) and A2780(ZD0473R) cell lines. The compound is believed to form a range of interstrand GG adducts with duplex DNA that induces global changes in the DNA conformation, unlike cisplatin and ZD0473 [also known as AMD473 and JM473: cis-(2-methylpyridine)(ammine)dichloroplatinum(II)] that form mainly intrastrand adducts that induces a local kink in a DNA strand. The increasing prevention of BamH1 digestion of form I and form II pBR322 plasmid DNA with the increase in concentration of the compound is believed to be due to interstrand binding that brings about global changes in DNA conformation.

Antineoplastic Agents↗
PubMed2006

Essential role of Ca2+ release channels in angiotensin II-induced Ca2+ oscillations and mesangial cell contraction.

The increased resistance of the glomerulus as a result of contractile dysfunction of mesangial cells (MCs) is associated with reduction of glomerular filtration rate and development of glomerulosclerosis. Evidences show MCs contraction changes with intracellular Ca(2+) concentration ([Ca(2+)](i)). Here, we explore the mechanism of angiotensin II (AngII)-induced Ca(2+) oscillations and MCs contraction. Primary MCs from 3-month-old and 28-month-old rats were used for detection of Ca(2+) oscillations and MC planar area with confocal microscopy. AngII could induce typical Ca(2+) oscillations and contraction of MCs. This process was abolished by thapsigargin, 2-aminoethoxydiphenyl borate, or 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphorylcholine, and partially inhibited by ryanodine, but could not be inhibited in the absence of extracellular Ca(2+). Ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate (InsP(3)) receptors displayed a strong colocalization, which may contribute to the amplification of Ca(2+) response. MLC(20) phosphorylation and MC planar area were associated with AngII-induced Ca(2+) oscillations. The frequency of Ca(2+) oscillations was dependent on the AngII concentration and correlated with the MCs' contractive extent, which could be attenuated by KN-93. The amplitude reduction of oscillations correlated with the decrease in aging-related contraction. In conclusion, [Ca(2+)](i) response of MCs to AngII is characterized by repetitive spikes through the following repetitive cycles: Ca(2+) release by phospholipase C -InsP(3) pathway, Ca(2+) amplification by Ca(2+)-activated RyRs and Ca(2+) reuptake by the endoplasmic reticulum. MCs contraction can be modulated by oscillations not only in an AngII-induced frequency-dependent mode but also in an aging-related, amplitude-dependent mode.

Angiotensin II↗
PubMed2006

Epidural cooling for selective brain hypothermia in porcine model.

BACKGROUND: Hypothermia has been shown to be neuroprotective in many animal models and several human trials of brain ischemic and trauma. However systemic hypothermia may result in fatal complications. This study was undertaken to test epidural cooling as a new method of inducing selective brain hypothermia. METHOD: Six adult swine (mean mass, 33.8+/-3.6 kg) were studied. Anesthesia was maintained with pentobarbital sodium (25 mg kg-1, i.v.) and pancuronium bromide (0.5 mg kg-1 h-1, i.v.). Five probes were placed in the rectum, deep brain, brain surface, epidural space, and room air for temperature monitoring respectively. Epidural cooling was performed using cold-saline (4 degrees C) perfusion into the epidural space through a flexible double-lumen catheter. The dripping speed of cold saline was controlled to maintain the target temperature. The changes of the epidural space pressure, complete blood counts, basic metabolic panels, tests for fibrinolysis and coagulation status were monitored to assess hypothermia-induced changes. FINDINGS: Following the epidural cooling perfused with cold-saline (4 degrees C) at mean dripping speed of 720 ml per hour, the local brain surface temperature could decrease rapidly to 17.3-21.6 degrees C within one minute, and deep brain temperature decreased to 27.2-29.7 degrees C within 5 minutes. The target temperatures were easily controlled by the dripping speed of cold saline (from mild to deep hypothermia). The rectal temperature was maintained at normal range within 6 perfusion hours. No arrhythmia was observed, and all hematological variables were within the normal range for swine. No increased intracranial pressure was induced by the cooling method. CONCLUSIONS: The data demonstrate that epidural space cooling was technically feasible and useful for selective brain hypothermia, and the target temperatures are easily controlled. The induction of hypothermia was rapid and maintained for a long period of time, whereas the body temperature was maintained within the normal range and without hemodynamic instability.

Animals↗
PubMed2006

Functional recovery of chronic complete idiopathic transverse myelitis after administration of neurotrophic factors.

STUDY DESIGN: Case report. OBJECTIVE: To evaluate the functional recovery of chronic complete idiopathic transverse myelitis (ITM) after administration of acidic fibroblast growth factor (aFGF). METHODS: A 28-year-old woman presented with a 4-year history of spastic paralysis, sensory level at T10, urinary retention and constipation due to ITM. In all, 20 microg aFGF bolus injection was applied via intradural lumbar puncture, which was repeated every 5 months for 15 months. RESULTS: At 3 weeks after first injection, the patient experienced vague sensation at approximately T12-L1 dermatomes. At 2 months after the second injection, muscle activities and gait pattern were recorded in bilateral gluteus and hip abductors as she ambulated with long leg brace and axillary crutches. Increased walking speeds, reduced pelvic tilting and reduced compensatory trunk rotation during the swing phase were also demonstrated as compared to the initial gait analysis. At 18 months after injection, motor evoked potentials were obtained in hip abductors of both legs. CONCLUSIONS: aFGF may increase the efficacy of spinal reactivation/regeneration and is a potential remedy for chronic transverse myelitis.

Adult↗
PubMed2006

QTLs associated with growth traits and abdominal fat weight and their interactions with gender and hatch in commercial meat-type chickens.

Associations between microsatellite markers and traits related to growth and fatness were investigated using resource broiler population. A sire-line x dam-line F1 male was backcrossed to 12 dam-line females to produce 24 sires and 47 dams of the backcross 1 (BC1) generation. These 71 parents were genotyped with 76 microsatellite markers. Following full-sib mating among the parents, 234 BC1-F2 progeny were phenotyped for five growth traits (body weight at 49 days from hatch, wog weight, front half weight, breast weight and tender weight) and abdominal fat weight. Maximum likelihood analysis was used to estimate the marker effects and to evaluate their statistical significance. Individual marker-trait analysis revealed 44 significant associations out of the 456 marker-trait combinations. Correction for multiple comparisons by controlling the false discovery rate (FDR) resulted in 12 significant associations at FDR = 10% with markers on chromosomes 1, 2, 5 and 13. Seventy-five percent of the 44 significant associations displayed no dependence on either hatch or gender; half of the remaining associations displayed dependence of the quantitative trait loci (QTL) effect on hatch x gender interaction. Thus, the analysed traits in this study may be dependent on external factors.

Abdominal Fat↗
PubMed2006

Intraspinal leakage of bone cement after vertebroplasty: a report of 3 cases.

We report 3 cases of vertebroplasty-induced intraspinal leakage of bone cement that were referred to us for management. Two patients received decompressive surgery, and one received rehabilitation. The gross surgical finding of yellowish dura mater and intradural fibrosis, adhesion, and microscopic finding of arachnoid membrane fibrosis are suggestive of late effect of thermal injury. These patients had residual lower extremity weakness and urinary and stool problems 13 months, 3 years, and 4.75 years post-vertebroplasty, respectively.

Aged↗
PubMed2006

An in-vitro investigation of the effect of a water additive and a new acidic primer on the tensile bond strength of composite resin to human enamel and dentine.

The aim of this study was to investigate the effect of a water additive on the bond strength of a composite restorative material to enamel and dentine which have undergone a range of surface treatments regimes. Human enamel and dentine specimens were prepared and divided into 3 surface treatment groups. Composite resin restorative material was bonded to the surface prepared enamel and dentine specimens. The tensile bond strength of the composite resin was measured using a Lloyd's testing machine. The tensile bond strength of composite resin to etched enamel surfaces using a standard etch technique was significantly greater than that to dentine (p < 0.05). For those specimens subjected to the addition of the water additive 'Alpron' the bond strength to the enamel was still significantly greater than to the dentine (p< 0.005). The addition of 'Alpron' to the water significantly improved the bond strength of composite to enamel and dentine when etched and placed with 'Prime&BondNT' (p < 0.05). There was no significant difference in bond strength of enamel and dentine specimens bonded using Xeno III (p> 0.05). However, the bond strength of dentine specimens bonded with Xeno III was significantly greater than other dentine specimens bonded with Prime&BondNT (p< 0.05). For those groups of specimens which included the water additive 'Alpron' in the regime, the tensile bond strength of the composite resin restorative material to enamel and dentine was greater than for those non water additive groups. The tensile bond strength of composite resin bonded to enamel surfaces prepared with 'Alpron' was significantly higher than that bonded to dentine surfaces.

Acid Etching, Dental↗
PubMed2005

Direct evidence of host genome acquisition by the alphaherpesvirus Marek's disease virus.

Many herpesviruses including Marek's disease virus (MDV), a poultry alphaherpesvirus, carry homologous host genes presumably acquired during viral evolution. We have characterized one recent acquisition by MDV in considerable detail. The virulent MDV strain Md11 previously was isolated from a commercial chicken and initially propagated on duck cells. In the process of cloning the entire Md11 genome in a bacterial artificial chromosome (BAC), we obtained an infectious clone in which the entire terminal repeat short segment was replaced with a portion of the duck genome that corresponds to chicken chromosome 19. This sequence is not predicted to express any protein even though it contains one exon of the VAMP1 gene. The replacement did not affect MDV replication in vitro, despite the virus having only one copy of ICP4. Furthermore, we have shown that the variant MDV genome containing the duck genome substitution is present in the parental Md11 population and has been maintained through several subsequent propagations of the virus on chicken cells. This finding provides direct evidence that host genome acquisition by MDV actually occurs during virus replication, and that one or more such MDV genomes with host sequences may exist within MDV viral stocks which tend to be polyclonal, due to the cell-associated nature of its infection process.

Animals↗
PubMed2005

Cost effectiveness and delivery study for future HIV vaccines.

Research teams from five countries, Brazil, China, Kenya, Peru and Thailand, have initiated a policy-maker survey on vaccine delivery, cost studies for future HIV vaccination programmes, and associated simulation modeling exercises analysing the relative cost-effectiveness of potential HIV vaccination strategies. The survey assesses challenges and opportunities for future country-level HIV vaccination strategies, providing data on the vaccine characteristics (e.g. vaccine efficacies for susceptibility, infectiousness and disease progression) and vaccination programme strategies to be considered in the cost-effectiveness modeling analyses. The study will provide decision-makers with modeling data on vaccination policy considerations that will assist in developing country-level capacities for future HIV vaccine policy adoption and effective delivery systems, and will help delineate the long-term financial requirements for sustainable HIV vaccination programmes. The WHO-UNAIDS HIV Vaccine Initiative and the collaborating researchers welcome comments or questions from policy makers, health professionals and other stakeholders in the public and private sectors about this effort to help advance policy and capacity related to future potential HIV vaccines.

AIDS Vaccines↗
PubMed2005

Digital redesign of observer-based weighting switch controller for cascaded analog systems with state saturation and external loads.

This paper presents an observer-based weighting switch controller for dealing with the problem of cascaded systems with state saturation and external loads. This method improves the generally poor transition response and output deviation caused by state saturation and external loads. In order to maintain the state-saturation limits, we adopt the evolutionary programming optimal search technique to find the optimal switching parameters for the weighted switch controller. Also, a digital redesign method is utilized to replace a designed high-gain analog controller with a low-gain digital controller. It is shown that the digitally redesigned outputs closely track the analogously controlled outputs. The digital redesign technique is then extended to find the digital version of the continuous-time observer. An illustrative example is demonstrated to show the effectiveness of the proposed procedure.

Journal Article↗
PubMed2004

Introduction to the DAPPLE Air Pollution Project.

The Dispersion of Air Pollution and its Penetration into the Local Environment (DAPPLE) project brings together a multidisciplinary research group that is undertaking field measurements, wind tunnel modelling and computer simulations in order to provide better understanding of the physical processes affecting street and neighbourhood-scale flow of air, traffic and people, and their corresponding interactions with the dispersion of pollutants at street canyon intersections. The street canyon intersection is of interest as it provides the basic case study to demonstrate most of the factors that will apply in a wide range of urban situations. The aims of this paper are to introduce the background of the DAPPLE project, the study design and methodology for data collection, some preliminary results from the first field campaign in central London (28 April-24 May 2003) and the future for this work. Updated information and contact details are available on the web site at http://www.dapple.org.uk.

Air Pollution↗
PubMed2004

Activation of phospholipase C-gamma1 in human keratinocytes by hyperosmolar shock without enzyme phosphorylation.

Human keratinocytes are exposed to strong physical changes, and have the potentiality to react to external stimuli by switching on adaptation mechanisms. In hyperosmotically shocked keratinocytes a rapid and strong increase in calcium has been observed. We showed that this increase could not be prevented by growing the cells in medium devoid of calcium and in the presence of EGTA, indicating that the intracellular calcium increase was due to delivery from internal stores. Further, we observed an increased synthesis of dyacylglycerol and inositol trisphosphates after shock, suggesting that phospholipase C mediates both events. Our experiments demonstrated that osmotic shock in human keratinocytes leads to activation of phospholipase C-gamma1, as measured using an in vitro assay system. This activation is independent of protein tyrosine phosphorylation and corresponded to a relocation of the enzyme to perinuclear membranes as shown by immunofluorescence.

Arachidonic Acid↗
PubMed2004

Electrochemical hydrodehalogenation of 2,4-dibromophenolin paraffin oil using a solid polymer electrolyte reactor.

A new technology for remediation of halogenated organics-oil systems, which can cause serious environmental problems, has been demonstrated using the electrochemical hydrodehalogenation of 2,4-dibromophenol (DBP) in paraffin oil in a solid polymer electrolyte reactor. The reactor has been evaluated in terms of cathode materials and structure and the ratio of the cathode surface area to the solution volume. A cathode of titanium minimesh with a palladium electrocatalyst produced by electrodeposition was particularly effective. Current efficiencies of up to 85% and percentage of DBP removal of up to 62%, space-time yields of up to 7.6 kg DBP m(-3) h(-1), and energy consumption as low as 1.6 kW h (kg of DBP)(-1) were achieved. The reactor showed stable operation for periods of up to 170 h. The results demonstrated that electroreduction could be an alternative technology to electrooxidation forthe treatment of wastes and toxic halogenated compounds, making the process simpler in comparison to electrooxidation.

Electrochemistry↗
PubMed2004

Chemosensitization of breast carcinoma cells with the use of bcl-2 antisense oligodeoxynucleotide.

This study was designed to observe whether the rates of apoptosis induced in the breast cancer cell line MCF-7 by 5-fluorouracil (5-FU) could be enhanced by transfecting bcl-2 antisense oligonucleotide (ASODN). In our experiment, bcl-2 ASODNs and control ODNs including untreated control, sense ODN and scrambled ODN, were transfected into MCF-7 cells. Changes in expression of the bcl-2 gene were examined by Western blot; cell growths were detected by MTT assay, and apoptosis rates were detected by flow cytometry (FCM). Expression of bcl-2 protein after transfection of bcl-2 ASODN was significantly lower than control ODNs. Moreover, incubation of MCF-7 with bcl-2 ASODN prior to 5-FU treatment caused remarkable loss of viable cells compared with all other control ODNs (P < 0.01). FCM showed the apoptosis rates for ASODN, untreated control, sense ODN and scrambled ODN (29.8 +/- 7.4)%, (8.0 +/- 2.3)%, (15.0 +/- 5.1)% and (16.5 +/- 7.1)%, respectively. Compared with control ODNs, ASODN achieved the strongest effect in terms of enhancing apoptosis (P < 0.01). These results suggest that combining bcl-2 ASODN with 5-FU led to synergistic cytotoxicity.

Antimetabolites, Antineoplastic↗
PubMed2004

Characterization of the distinct orthotopic bone-forming activity of 14 BMPs using recombinant adenovirus-mediated gene delivery.

Efficacious bone regeneration could revolutionize the clinical management of bone and musculoskeletal disorders. Although several bone morphogenetic proteins (BMPs) (mostly BMP-2 and BMP-7) have been shown to induce bone formation, it is unclear whether the currently used BMPs represent the most osteogenic ones. Until recently, comprehensive analysis of osteogenic activity of all BMPs has been hampered by the fact that recombinant proteins are either not biologically active or not available for all BMPs. In this study, we used recombinant adenoviruses expressing the 14 types of BMPs (AdBMPs), and demonstrated that, in addition to currently used BMP-2 and BMP-7, BMP-6 and BMP-9 effectively induced orthotopic ossification when either AdBMP-transduced osteoblast progenitors or the viral vectors were injected into the quadriceps of athymic mice. Radiographic and histological evaluation demonstrated that BMP-6 and BMP-9 induced the most robust and mature ossification at multiple time points. BMP-3, a negative regulator of bone formation, was shown to effectively inhibit orthotopic ossification induced by BMP-2, BMP-6, and BMP-7. However, BMP-3 exerted no inhibitory effect on BMP-9-induced bone formation, suggesting that BMP-9 may transduce osteogenic signaling differently. Our findings suggest that BMP-6 and BMP-9 may represent more effective osteogenic factors for bone regeneration.

Adenoviridae↗