Biomedical subjects
Publications and source records attributed to H Wang.
We describe the use of the semi-empirical molecular orbital method PM3 (parametric method 3) to study the electronic structure of iron-sulphur proteins. We first develop appropriate parameters to describe models of the redox site of rubredoxins, followed by some preliminary calculations of multinuclear iron systems of relevance to hydrogenases.
Treatment of wastewater generally results in elevated natural 15N abundance (delta15N) in the effluent and sludges. For example, high delta15N values are found in treated sewage effluent, biosolids, and other wastes that are commonly applied to land. In contrast, N deficient coniferous forest soils usually have a low delta15N. When wastes with high delta15N values are applied to land, their distinctive delta15N signature can potentially be used to trace the fate of waste-derived N in the ecosystem. In this paper, we provide an overview of the use of delta15N in land application of wastes, including New Zealand case studies on tracing nitrogen in forest ecosystems.
Using stable N isotopes, the fate of effluent-derived N has been determined within a land based municipal effluent irrigation scheme. Over 900 metric tonnes(t) of effluent-derived N have been applied to 192 ha of production conifer forest near Rotorua (NZ) over the past 11 years. The effluent N has a natural isotopic signal, generated by the treatment process, allowing it to be traced into various components of the system. Using this isotopic signal, a realistic approximation of storage capacity of various components of the system has been generated, including a calculation of the contribution of effluent N exiting the catchment via stream flow. Forest storage accounts for 50% of the applied N with a considerable proportion of that immobilized in wood and soil. The wetland, although not intensively sampled, retains 115 t, (13%) of the applied N. Denitrification, including that occurring within the wetland, accounts for 23 t (3%). Nitrogen isotope data confirm that the rise in NO3 concentrations is directly attributable to effluent N. Currently 88% of NO3-N in the stream is effluent-derived. Using current N isotope values for the stream and extrapolating over the discharge period, export of effluent N via the stream is estimated as 263 t (29%) of the applied N. Overall the forest and wetland ecosystem has intercepted or denitrified 65% of applied N, with 29% lost to the stream, and 50 t (5%) unaccounted for. The forest ecosystem is currently over-supplied with N and a number of management implications flows from these findings. In the long term the continued application of effluent N to the current irrigation area is not sustainable.
Summary Single-particle fluorescence microscopy of association/dissociation is required for analysis of biological assembly reactions. Toward achieving this goal, Wang et al. (J. Microsc., 2004, 213, 101-109) used molten agarose to concentrate thermally diffusing particles in a thin zone of solution next to the surface of a coverglass (plane of concentration). The present study details the first real-time, single-particle analysis of the association/dissociation of thermally diffusing particles in the plane of concentration. The test particles were procapsids of bacteriophage lambda (radius = 31 nm). Quantification of thermal motion was developed and used to determine whether co-diffusing particles were bound to each other. The data are explained by (1) the presence of a molten agarose-generated barrier that is 93-155 nm from the coverglass surface, and (2) non-random orientation of procapsid dimers in the plane of concentration.
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BACKGROUND: Epidermal Langerhans cells (LCs) play an important role in cutaneous immunological reactions. Freshly obtained or intraepidermal LCs are incapable of activating autologous naive T cells. However, when they are cultured for 2-3 days, LCs are able to activate autologous T cells. It has been proposed that haptoglobin (Hp) is the inhibitor that prevents LC functional transformation in the skin. Abundant Hp has been found in the cytoplasm of epidermal LCs. However, the source of Hp in LCs has not been addressed. OBJECTIVES: To determine the expression of Hp in epidermal cells, and to provide evidence that there is a functional relationship between LCs and keratinocytes (KCs) through Hp. METHODS: Normal human epidermal cells and HaCaT cells were used for detection of Hp mRNA by in situ hybridization and reverse transcription-polymerase chain reaction, and Hp protein by immunohistochemical staining, immunofluorescence counterstaining and Western blotting. RESULTS: Hp mRNA was expressed in normal human KCs and HaCaT cells, but not in normal human epidermal LCs. Hp protein was detected by immunohistochemical staining and immunofluorescence counterstaining in CD1a+ epidermal dendritic cells (LCs), but not in KCs. Hp protein was weakly expressed by HaCaT cells. CONCLUSIONS: Hp mRNA is present in normal human KCs and HaCaT cells, suggesting that they have the potential to synthesize Hp protein. Normal human epidermal LCs are unable to synthesize Hp protein by themselves, although they have abundant Hp protein in their cytoplasm. It is likely that LCs acquire Hp through an exogenous pathway.
White spot syndrome virus (WSSV) is a serious pathogen of aquatic crustaceans. Little is known about its transmission in vivo and the immune reaction of its hosts. In this study, the circulating haemocytes of crayfish, Procambarus clarkii, infected by WSSV, and primary haemocyte cultures inoculated with WSSV, were collected and observed by transmission electron microscopy and light microscopy following in situ hybridization. In ultra-thin sections of infected haemocytes, the enveloped virions were seen to be phagocytosed in the cytoplasm and no viral particles were observed in the nuclei. In situ hybridization with WSSV-specific probes also demonstrated that there were no specific positive signals present in the haemocytes. Conversely, strong specific positive signals showed that WSSV replicated in the nuclei of gill cells. As a control, the lymphoid organ of shrimp, Penaeus monodon, infected by WSSV was examined by in situ hybridization which showed that WSSV did not replicate within the tubules of the lymphoid organ. In contrast to previous studies, it is concluded that neither shrimp nor crayfish haemocytes support WSSV replication.
OBJECTIVE: There is an ongoing debate whether there is a link between a history of atopy and cancer risk. The purpose of this paper is to review the published epidemiological studies on the association between atopy and the risk of cancers. METHODS: Through an electronic search (January 1986-April 2004) with an additional review of cited references, we identified studies with quantitative data on the relation of atopy (irrespective of its definition or subtype) to cancer (different cancer sites). RESULTS: The protective effect of atopy in colorectal cancer has been observed consistently in the case-control studies, but not in cohort studies. A consistent inverse association between self-reported atopy and glioma risk has been shown, but there is absence of such an association for meningioma. In most studies, the risk of leukaemia, in particular childhood leukaemia, tends to be lower among people with a history of atopy. Studies, which looked at, the association between atopic diseases and risk of cancers of pancreatic, breast, lymphoma showed varying outcomes. Most studies on the atopy-pancreatic cancer relation suggested an inverse association. For lymphoma, most studies have shown no substantial association. Overall evidence indicates an increased risk of lung cancer among persons with a history of asthma. CONCLUSION: Despite the mixed results, the emerging picture from most of the currently available epidemiological data indicate that atopic disease is associated with a reduced risk for cancer. Further research should focus on a more carefully defined 'atopy' status and manifestation of different atopic diseases, to advance our understanding of the role that allergies might play in the risk of developing cancer.
In this study, HLA-DRB1 gene was genotyped by using the microarray technique. Oligonucleotide probes were designed based on partial sequences of various genotypes of HLA-DRB1, and were fixed on a silylated slide to form a microarray. The second exon of HLA-DRB1 gene in the extracted genomic DNA samples was amplified and labelled by means of polymerase chain reaction (PCR); then it was hybridized to the microarray. The microarray was scanned, and the result was analysed in order to determine the genotypes of HLA-DRB1 of the tested sample. A total of 1574 of 1592 clinical samples had accordant results of genotypes in either microarray assay or PCR-SSP assay; 8 of 10 samples that had inconsistent results of genotypes were proved to be microarray-assay reliable by confirmation of DNA sequencing. It is concluded that microarray is an alternative reliable method for HLA-DRB1 genotyping.
AIMS: This paper presents two cases of muscle infarction involving four major muscles of the anterior abdominal wall (case 1) and pectoralis major (case 2) in individuals with diabetes. METHODS: Erythrocyte sedimentation rate (ESR) and creatine kinase (CK) were measured and Doppler ultrasound, an open muscle biopsy (case 1) and magnetic resonance imaging (MRI) (case 2) were performed. RESULT: The diagnosis of muscle infarction was made by histological findings and MRI images with hyper-intensive signals on a gadolinium-enhanced T2-weighted sequence, respectively. Both patients were treated with bed rest, immobilization of the involved extremities, analgesia and intensive insulin therapy. In addition, anticoagulant drugs such as low molecular weight heparin sodium and cilostazol, and some traditional Chinese medicines such as ligustrazine and salvia miltiorrhiza were administered. The symptoms of both patients resolved gradually after 3 weeks. However, muscle infarction reoccurred in case 1 on the opposite side of the abdomen and recovered after 40 days. CONCLUSIONS: This is the first report of muscle infarction involving the muscles of anterior abdominal walls and pectoralis major in diabetes. MRI is the best non-invasive technique and T2-weighted imaging is the most valuable method for the diagnosis. In addition to supportive therapy, administration of anticoagulant agents and some Chinese traditional medicine may be useful in symptom relief.
We evaluated the engraftment of donor cells from unrelated cord blood into adult patients with severe aplastic anemia (SAA) and the outcome of allo-CBSCT (cord blood stem cell transplantation). Nine patients were conditioned with decreased dosage of immunosuppressive agents of CTX (60 mg/kg) and ALG (120 mg/kg). The prophylaxis of GVHD consisted of standard CsA and MTX. Patients have a media age of 25.3 yr (range: 15-37), and a median weight of 57.2 kg (range: 52.5-60) at the time of transplantation. Cord blood searches were all conducted at Guangzhou Cord Blood Bank. The engraftment state of the donor cells into recipients was confirmed by microsatellite DNA fingerprinting and fluorescent quantitative PCR analysis. Engrafted evidence has been found in seven patients involved by biomolecular analyses showing donor-recipient mixed chimerism post-transplant which was stable and persistent. After a median follow up of 32.2 months (range: 4-69), seven patients were alive and disease free. This study shows that durable donor-recipient stable mixed chimerism can be achieved by unrelated CBSCT in patients with SAA. Umbilical cord blood could be employed as a source of hematopoietic stem cell for adult transplantation.
Islet transplantation is being offered increasingly for selected patients with unstable type 1 diabetes. Percutaneous transhepatic portal access avoids a need for surgery, but is associated with potential risk of bleeding. Between 1999 and 2005, we performed 132 percutaneous transhepatic islet transplants in 67 patients. We encountered bleeding in 18/132 cases (13.6%). In univariate analysis, the risk of bleeding in the absence of effective track ablation was associated with an increasing number of procedures (2nd and 3rd procedures with an odds ratio (OR) of 9.5 and 20.9, respectively), platelets count <150,000 (OR 4.4), elevated portal pressure (OR 1.1 per mm Hg rise), heparin dose > or =45 U/kg (OR 9.8) and pre-transplant aspirin (81 mg per day) (OR 2.6, p = 0.05). A multivariate analysis further confirmed the cumulative transplant procedure number (p < 0.001) and heparin dose > or =45 U/kg (p = 0.02) as independent risk factors for bleeding. Effective mechanical sealing of the intrahepatic portal catheter tract with thrombostatic coils and tissue fibrin glue completely prevented bleeding in all subsequent procedures (n = 26, p = 0.02). We conclude that bleeding after percutaneous islet implantation is an avoidable complication provided the intraparenchymal liver tract is sealed effectively.
BACKGROUND: Despite an extensive literature, the impact of both adjunctive steroid therapy and delayed diagnosis on the outcome of childhood pneumococcal meningitis is controversial. AIM: To determine the independent contribution of corticosteroid therapy and delayed diagnosis on the outcome of childhood pneumococcal meningitis in a representative population with good access to medical services. METHODS: Data were obtained from laboratories and hospital records to assemble a population register in Sydney, Australia, 1994-99. Follow up questionnaires were completed by attending physicians. RESULTS: A total of 122 cases of pneumococcal meningitis aged 0-14 years were identified. Almost 50% of 120 children with available records either died (n = 15) or had permanent neurological impairment (n = 39). Early use (before or with parenteral antibiotics) of corticosteroids protected against death or severe morbidity (adjusted OR 0.21, 95% CI 0.05 to 0.77). Delayed diagnosis was associated with increased morbidity in survivors (OR 3.4, 95% CI 1.03 to 11.4) but not with increased mortality. CONCLUSION: In a population with good access to health care and after adjusting for other known prognostic variables, early recognition of pneumococcal meningitis and treatment with adjunctive dexamethasone significantly improves outcomes. These data add to those from randomised controlled trials. Implementation requires development of protocols and guidelines for use in emergency departments.
PROBLEM: Advance cardiac life support (ACLS) training does not address coordination of team resources to improve the ability of teams to deliver needed treatments reliably and rapidly. Our objective was to use a human simulation training educational environment to develop multidisciplinary team skills and improve medical emergency team (MET) performance. We report findings of a crisis team training course that is focused on organization. SETTING: Large center for human simulation training at a university affiliated tertiary care hospital. PARTICIPANTS: Ten courses were delivered and 138 clinically experienced individuals were trained (69 critical care nurses, 48 physicians, and 21 respiratory therapists). All participants were ACLS trained and experienced in responding to cardiac arrest situations. COURSE DESIGN: Each course had four components: (1) a web based presentation and pretest before the course; (2) a brief reinforcing didactic session on the day of the course; (3) three of five different simulated scenarios; each followed by (4) debriefing and analysis with the team. Three of five simulator scenarios were used; scenario selection and order was random. Trainees did not repeat any scenario or role during the training. Participants were video recorded to assist debriefing. Debriefing focused on reinforcing organizational aspects of team performance: assuming designated roles independently, completing goals (tasks) assigned to each role, and directed communication. MEASURES FOR IMPROVEMENT: Participants graded their performance of specific organizational and treatment tasks within specified time intervals by consensus. Simulator "survival" depended on supporting oxygenation, ventilation, circulation within 60 seconds, and delivering the definitive treatment within 3 minutes. EFFECTS OF CHANGE: Simulated survival (following predetermined criteria for death) increased from 0% to 89%. The initial team task completion rate was 10-45% and rose to 80-95% during the third session. LESSONS LEARNT: Training multidisciplinary teams to organize using simulation technology is feasible. This preliminary report warrants more detailed inquiry.
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