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Biomedical subjects

G M Wood

Publications and source records attributed to G M Wood.

At least 19 recordsLinked to original sources
PubMed2003

Estimation of genetic parameters for concentrations of milk urea nitrogen.

The objective of this study was to use field data collected by dairy herd improvement programs to estimate genetic parameters for concentrations of milk urea nitrogen (MUN). Edited data were 36,074 test-day records of MUN and yields of milk, fat, and protein obtained from 6102 cows in Holstein herds in Ontario, Canada. Data were divided into three sets, for the first three lactations. Two analyses were performed on data from each lactation. The first procedure used ANOVA to estimate the significance of the effects of several environmental factors on MUN. Herd-test-day effects had the most significant impact on MUN. Effects of stage of lactation were also important, and MUN levels tended to increase from the time of peak yield until the end of lactation. The second analysis used a random regression model to estimate heritabilities and genetic correlations of MUN and the yield traits. Heritability estimates for MUN in lactations one, two, and three were 0.44, 0.59, and 0.48, respectively. Heritabilities for the yield traits were of a similar magnitude. Little relationship was observed between MUN and yield. Raw phenotypic correlations were all <0.10 (absolute value). Genetic correlations with production traits were close to zero in lactations one and three and only slightly positive in lactation two. The results indicate that selection on MUN is possible, but relationships between MUN and other economically important traits such as metabolic disease and fertility are needed.

Animals↗
PubMed2001

Emerging technologies in health care and the patient encounter of the future.

In the last five years, the Web has changed the way information is disseminated, knowledge is gained, and health care is provided. Even though the health care industry has yet to fully realize the potential of the Internet, the Web is only the beginning. Several emerging technologies will be changing the rules again. With new forms of network connectivity and faster, new wireless technologies, the adoption rate of mobile, handheld computers in health care will grow feverishly. Intelligent, autonomous software agents that guide the patient through the continuum of care will extend the reach of health care providers to all places at all times. The author discusses these new concepts, how they might be applied in health care, and the doctor-patient health care transaction.

Diffusion of Innovation↗
PubMed2000

The changing role of the health care chief information officer.

Information is the lifeblood of the health care organization. In the past, chief information officers were responsible for nothing else but assuring a constant flow of information. Today, they are being asked to do a great deal more. From E-business to E-health strategy, the chief information officer is the focal point of an organization's ability to leverage new technology.

Administrative Personnel↗
PubMed1997

Protein S alters the active site location of activated protein C above the membrane surface. A fluorescence resonance energy transfer study of topography.

The location of the active site of membrane-bound activated protein C (APC) relative to the phospholipid surface was determined both in the presence and absence of its cofactor, protein S, using fluorescence resonance energy transfer (FRET). APC was chemically modified to create the FRET donor species, Fl-FPR-APC, with a fluorescein dye (Fl) covalently attached to the active site via a D-Phe-Pro-Arg (FPR) tether and located in the active site near S4. FRET was observed when Fl-FPR-APC was titrated in the presence of Ca2+ ions with phosphatidylcholine/phosphatidylserine (4:1) vesicles containing the FRET acceptor, octadecylrhodamine (OR). Assuming a random orientation of transition dipoles (kappa2 = 2/3), the average distance of closest approach between the fluorescein in the active site of the membrane-bound APC and the OR at the membrane surface is 94 A. The same calcium-dependent distance was obtained for both small and large unilamellar vesicles and for vesicles that contained phosphatidylethanolamine. The active site of membrane-bound APC is therefore located far above the phospholipid surface. Upon addition of protein S, the efficiency of Fl-FPR-APC to OR energy transfer increased due to a protein S-dependent rotational and/or translational movement of the APC protease domain relative to the surface. If this movement were solely translational, then the average height of the fluorescein in the membrane-bound APC.protein S complex would be 84 A above the surface. The extent of Fl-FPR-APC to OR energy transfer was unaltered by the addition of thrombin-inactivated protein S. The protein S effect was also specific for APC, since the addition of protein S to similarly-labeled derivatives of factor Xa, factor IXa, or factor VIIa did not alter the locations of their active sites. This direct measurement demonstrates that the binding of the protein S cofactor to its cognate enzyme elicits a relocation of the active site of APC relative to the membrane surface and thereby provides a structural explanation for the recently observed protein S-dependent change in the site of factor Va cleavage by APC.

Animals↗
PubMed1997

Ochratoxin A in wheat: certification of two reference materials.

The preparation of two wheat reference materials and the certification of their ochratoxin A content is described. The materials were prepared and certified within the European Commission. Measurements and Testing Programme (M&T). The first and second phases of this project, two intercomparisons of procedures for the determination of ochratoxin A in wheat, at levels of approximately 13 micrograms/kg, and 7 micrograms/kg, respectively have already been reported. This paper describes the work carried out in certification of the ochratoxin A content (mass fraction) of two wheat reference materials: a blank wheat CRM 471, and a contaminated wheat, CRM 472. These materials were prepared for use in the second intercomparison referred to above and reported previously. Reference material CRM 472 was prepared from naturally-contaminated wheat blended with the blank wheat (CRM 471). Details are given of the milling, blending and packaging procedure, and the checks to ensure homogeneity and stability of the material. The certification exercise was carried out by 15 laboratories using a variety of extraction and clean-up procedures, and the certified ochratoxin A content (mass fraction) of CRM 471 was < 0.6 microgram/kg. The value for CRM 472 was 8.2 micrograms/kg with an uncertainty of 1.0 microgram/kg.

Calibration↗
PubMed1996

Ochratoxin A in wheat: a second intercomparison of procedures.

The European Commission, Measurements and Testing Programme (BCR) has undertaken a project to improve methodology and to prepare certified reference materials for ochratoxin A determination. The first phase of this project, an intercomparison of procedures for the determination of ochratoxin A in wheat, at a content of approximately 13 micrograms/kg, has already been reported. The second intercomparison study, described in this paper, involved 26 European laboratories, from 11 countries, which analysed wheat naturally contaminated at a level of approximately 7 micrograms/kg, and a 'blank' wheat sample (ochratoxin A content < 0.2 microgram/kg). The participants used a variety of procedures which involved different extraction solvents and clean-up procedures. All laboratories used HPLC as the determinative step. Some laboratories also used immunoaffinity column clean-up in comparison with their normal method. Recoveries of the normal methods used by laboratories ranged from 58 to 114%; only three laboratories obtained recoveries outside the accepted range of 70 to 110%. Recoveries of the immunoaffinity column methods, using two sources of column, ranged from 58 to 114% for one and from 4 to 86% for the other. The between-laboratory reproducibility coefficient of variation for all results was 34% for the normal methods, and 34 and 42% for the two types of immunoaffinity columns. It was noted that, after the results were corrected for spike recovery, some laboratories became outliers owing to low spike recoveries. Further investigations of the spiking protocols used by each laboratory showed that the time left for evaporation of the spiking solvent was crucial to the recovery obtained.

Chromatography, High Pressure Liquid↗
PubMed1996

Moraxella catarrhalis: pathogenic significance in respiratory tract infections treated by community practitioners.

We prospectively studied the pathogenic significance of Moraxella (Branhamella) catarrhalis isolated from 212 patients of community practitioners in Australia. This organism was most commonly isolated during winter and early spring, and 92% of isolates were beta-lactamase producers. On the basis of predetermined clinical and microbiological criteria, 42% of the isolates were definitely pathogenic, 7% were probably pathogenic, 21% were of indeterminate pathogenicity, and 30% were nonpathogenic. Factors associated with pathogenic significance included pneumonia or bronchitis (87% of patients), predisposing respiratory or systemic conditions (62%), isolation from sputum, and pure isolation. Thirty-six percent of patients were < 5 years old, but only 9% of isolates from these patients were pathogenic or probably pathogenic, a finding that reflects the fact that nasal-swab and nasopharyngeal-aspirate sampling is a common practice. Isolates from older patients were more likely to be pathogenically significant. An assessment of the pathogenic significance of M. catarrhalis isolated from a patient in a community practice should take into consideration factors such as the patient's age, clinical illness, and underlying conditions; the presence of other organisms; and the source of the isolate.

Adolescent↗
PubMed1995

Ochratoxin A in cereals and the BCR-M&T-projects.

Reliable analytical procedures and certified reference materials are essential for the establishment and enforcement of tolerance levels for ochratoxin A in foods. The inadequacy of analytical procedures, together with the need for certified reference materials, led the Commission of the European Communities Community Bureau of Reference (BCR) to undertake a project to prepare suitable reference materials for ochratoxin A in wheat, in order to improve methodology and to harmonise agreement of results between member states. The first intercomparison study indicated problems in the analysis due to the influence of co-extractives in the matrix, and demonstrated that further work was necessary to improve recovery, clean-up and reproducibility. The second intercomparison study, in the EC Measurements and Testing Programme, correlated the performance of the different methods for ochratoxin A measurement in a separate batch of contaminated wheat, and compared novel immunoaffinity column methods with the standard laboratory methods. Results were obtained from 26 laboratories within 11 European countries, which therefore gives a good representation of the scope of methods currently used in Europe. Considerable improvements in the determination of ochratoxin A were noted compared with the first intercomparison study.

Carcinogens↗
PubMed1994

Characteristics of HPRT-mutant T cell lines in a lupus patient treated with cyclophosphamide.

This report describes T cell lines derived from a patient with subacute cutaneous lupus after treatment with intravenous pulse cyclophosphamide. We selected for mitotically active, hypoxanthine-guanine phosphoribosyltransferase-deficient (HPRT-) T cells, by culture in a selective medium containing 6-thioguanine. When HPRT- cell lines were derived 6 days after pulse cyclophosphamide (CYC) treatment, they were predominantly CD8+ and T cell receptor (TCR) gamma/delta+, producing interferon-gamma (IFN gamma). Cell lines derived 21 days after CYC treatment were CD4+, TCR alpha/beta+ and produced both IFN gamma and interleukin-4. These results support a possible role for gamma/delta+ T cells in subacute cutaneous lupus and suggest a mechanism for the therapeutic effect of CYC.

Adult↗
PubMed1992

Studies of bone marrow progenitor cells in lupus-prone mice. I. NZB marrow cells demonstrate increased growth in Whitlock-Witte culture and increased splenic colony-forming unit activity in the Thy-1-, lineage- population.

Previous studies have demonstrated that NZB marrow can transfer features of autoimmunity. Therefore, we undertook a study of NZB marrow to determine whether it demonstrated any phenotypic abnormalities. In Whitlock-Witte cultures, NZB marrow cells generated nonadherent cells at low seeding densities, densities at which marrow from other strains did not generate nonadherent cells. In contrast, NZB marrow grew less well than controls in Dexter cultures. Inasmuch as the latter favor growth of granulocyte-macrophage precursors and the former B cells, these results suggest a possible skewing of NZB marrow cells toward lymphocyte production. Unfractionated marrow cells from NZB mice were found to produce 10-fold more splenic colonies in lethally irradiated recipients than marrow cells from control mice. This result was independent of the genotype of the recipient. When the progenitor Thy-1lo, Lin- marrow subpopulation was studied, NZB mice did not differ substantially from controls regarding splenic CFU. Therefore, Thy-1-, Lin- marrow cells were studied as a possible source of the excess splenic CFU in NZB mice. Indeed, the NZB Thy-1-, Lin- population contained 30-fold more splenic CFU than did the Thy-1-, Lin- population from control mice. These results suggest that NZB mice have unusual marrow progenitor cells; such cells may play a role in their autoimmune disease.

Animals↗
PubMed1992

Clinical features of human infection with Scedosporium inflatum.

We report on 17 Australian cases of human infection or colonization with Scedosporium inflatum. The spectrum of clinical manifestations was similar to that in infection caused by Scedosporium apiospermum. The patients were classified into three groups. Four immunocompetent patients who presented with localized infections of a joint, nail bed, eye, or sphenoidal sinus made up the first group. Our first case, in a boy with posttraumatic septic arthritis, responded to surgical drainage with amphotericin B followed by treatment with itraconazole. The other three cases were cured by surgery alone. The second group consisted of five immunocompromised patients who presented with disseminated infections in a variety of sites. Four of these patients did not respond to antifungal therapy and died. The fifth apparently responded to antifungal drugs after correction of his neutropenia. The third group included eight patients with asymptomatic colonization in the external ear (five cases) or respiratory secretions (three cases). The nine isolates of S. inflatum tested by both disk and agar dilution methods were resistant to antifungal drugs. In our first case, which responded clinically to itraconazole, the MIC of this drug for the fungal isolate was 25 micrograms/mL. Thus S. inflatum can cause a broad spectrum of human infections whose severity and prognosis depend largely on the host's immune status.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Isolated hepatitis B core antibody--can response to hepatitis B vaccine help elucidate the cause?

The finding of a positive hepatitis B core antibody (anti-HBc) in the absence of hepatitis B surface antigen (HBsAg) or hepatitis B surface antibody (anti-HBs) is relatively uncommon. This finding is known to occur during the 'window period' of acute hepatitis B between loss of HBsAg and the appearance of anti-HBs. It may also occur with active infection or following resolution. The aim of this study was to determine if response to hepatitis B vaccination would allow the separation of these subgroups of patients with isolated anti-HBc. Seventeen patients with persistent isolated core antibody were vaccinated and serum obtained at 2, 4 and 8 weeks. Results were compared with a seronegative control group. Six subjects (35%) but no control patients (p = 0.016) responded with a titre of greater than 50mIU/mL at two weeks, suggesting an anamnestic response due to prior infection and immunity. A further seven subjects (41%) finally seroconverted (anti-HBs titre greater than 10mIU/mL) thus excluding chronic infection and suggesting initial false positive results. Only two subjects did not respond to a full course of vaccination, but neither they nor any other subjects were positive for HBV DNA. These results indicate that hepatitis B vaccination and subsequent measurement of anti-HBs will identify evidence of past infection in the form of an anamnestic response in up to one third of the patients and will also exclude chronic infection on the grounds of a normal vaccine response in a majority of the remainder.

Adult↗
PubMed1991

Is persistent adenovirus 12 infection involved in coeliac disease? A search for viral DNA using the polymerase chain reaction.

It has been shown that partial amino acid sequence homology between alpha gliadin and an early region protein (E1B-58 kDa) of adenovirus 12 results in immunological cross reaction. This led to the proposal that prior infection by adenovirus 12 could be associated with the development of coeliac disease. To examine this hypothesis, evidence was sought of persistent adenovirus 12 infection in the small intestinal mucosa of patients with coeliac disease. DNA isolated from biopsy samples from 24 control and 18 coeliac disease patients was analysed by the polymerase chain reaction for adenovirus 12 DNA encoding the E1B-58 kDa protein. Four of 18 coeliac disease and two of 24 control patients were positive. There is thus a low prevalence of this infection on both groups of patients but certainly no significantly increased incidence in coeliac disease. These results suggest that persistent adenovirus 12 infection is not a major element in the pathogenesis of coeliac disease.

Adenoviridae↗
PubMed1991

Small bowel morphology in British Indian and Afro-Caribbean subjects: evidence of tropical enteropathy.

Distal duodenal biopsy specimens taken from 30 white, 35 Indian, and 20 Afro-Caribbean residents of West Birmingham during routine endoscopy for dyspepsia, were assessed by dissecting microscopy and morphometry. Finger-shaped villi were significantly less frequent in the Indian and Afro-Caribbean subjects than in the white subjects when assessed by dissecting microscopy (p less than 0.005), and both immigrant groups had decreased mucosal thickness (p less than 0.01), villous height (p less than 0.001), villous:crypt ratios (p less than 0.01) and enterocyte height (p less than 0.05) compared with the white group. In the Indian subjects, villous height and villous:crypt ratios correlated significantly with the time since the last visit to the Indian subcontinent (p less than 0.005). Serum alkaline phosphatase values were significantly higher in the Indian subjects compared with the whites (p less than 0.02), and serum globulins were increased in both the Afro-Caribbean and Indian subjects (p less than 0.01). There were no correlations between morphometric indices and body habitus or biochemical or haematological indices and the long term effect of the morphological changes is not clear.

Adolescent↗
PubMed1989

Chronic liver disease. A case control study of the effect of previous blood transfusion.

A means of assessing hepatitis NANB virus infection, via blood transfusion, as a cause of chronic liver disease was investigated in a hospital in each of two cities in England. Patients with chronic liver disease were matched for age and sex with other patients in the same hospital and histories taken included details of previous operations and blood transfusions; if these were within ten years of the study enquiries were made of hospital records officers. All positive histories were found correct, but about one third of previous transfusions had been omitted by both case and control patients. Sixty-seven male and 35 female patients with chronic liver disease and their controls were included in analyses. The only clear difference which emerged related to residence for more than a year in the Middle or Far East by male case- (40%) or control- (21%) patients (P less than 0.05). The exclusion of patients with this history left only 34 pairs in which five (15%) of the case patients and one (3%) of the control patients had a transfusion history: this difference was not statistically significant. Although the study results have shown no clear evidence of blood transfusion as a major cause of chronic liver disease in Britain, the study method, with sufficient numbers to allow analyses of newly diagnosed patients with confirmed transfusion histories, could be used to provide an ongoing assessment of the risk.

Adolescent↗
PubMed1988

Vitamin K-dependent carboxylase. Stoichiometry of vitamin K epoxide formation, gamma-carboxyglutamyl formation, and gamma-glutamyl-3H cleavage.

The rat liver microsomal vitamin K-dependent carboxylase catalyzes the carboxylation of peptide-bound glutamyl residues to gamma-carboxyglutamyl (Gla) residues with the concomitant formation of vitamin K 2,3-epoxide (KO). These studies have demonstrated that the half-reaction, formation of KO, occurs in the absence of carboxylation at low glutamyl substrate concentration but that the ratio of KO/Gla approaches unity as the glutamyl substrate concentration is increased. Utilization of the carboxylase substrate Phe-Leu-[gamma-3H] Glu-Glu-Leu has demonstrated that the ratios of KO/gamma-C-H bonds cleaved and Gla/gamma-C-H bonds cleaved are equivalent at high substrate concentrations and that these ratios approach unity. At low substrate concentrations, KO formation occurs at a higher rate than gamma-H bond cleavage. These data are consistent with a mechanism involving the formation of an oxygenated intermediate from vitamin KH2 and O2 that is converted to KO during hydrogen abstraction from the gamma-position of the Glu substrate. In the absence of a Glu substrate, the intermediate is converted to KO by a mechanism not coupled to glutamyl activation.

1-Carboxyglutamic Acid↗