Search PubMed⌕ Search

Biomedical subjects

M Ward

Publications and source records attributed to M Ward.

At least 91 records · Page 5Linked to original sources
PubMed2000

Penicillopepsin-JT2, a recombinant enzyme from Penicillium janthinellum and the contribution of a hydrogen bond in subsite S3 to k(cat).

The nucleotide sequence of the gene (pepA) of a zymogen of an aspartic proteinase from Penicillium janthinellum with a 71% identity in the deduced amino acid sequence to penicillopepsin (which we propose to call penicillopepsin-JT1) has been determined. The gene consists of 60 codons for a putative leader sequence of 20 amino acid residues, a sequence of about 150 nucleotides that probably codes for an activation peptide and a sequence with two introns that codes for the active aspartic proteinase. This gene, inserted into the expression vector pGPT-pyrG1, was expressed in an aspartic proteinase-free strain of Aspergillus niger var. awamori in high yield as a glycosylated form of the active enzyme that we call penicillopepsin-JT2. After removal of the carbohydrate component with endoglycosidase H, its relative molecular mass is between 33,700 and 34,000. Its kinetic properties, especially the rate-enhancing effects of the presence of alanine residues in positions P3 and P2' of substrates, are similar to those of penicillopepsin-JT1, endothiapepsin, rhizopuspepsin, and pig pepsin. Earlier findings suggested that this rate-enhancing effect was due to a hydrogen bond between the -NH- of P3 and the hydrogen bond accepting oxygen of the side chain of the fourth amino acid residue C-terminal to Asp215. Thr219 of penicillopepsin-JT2 was mutated to Ser, Val, Gly, and Ala. Thr219Ser showed an increase in k(cat) when a P3 residue was present in the substrate, which was similar to that of the wild-type, whereas the mutants Thr219Val, Thr219Gly, and Thr219Ala showed no significant increase when a P3 residue was added. The results show that the putative hydrogen bond alone is responsible for the increase. We propose that by locking the -NH- of P3 to the enzyme, the scissile peptide bond between P1 and P1' becomes distorted toward a tetrahedral conformation and becomes more susceptible to nucleophilic attack by the catalytic apparatus without the need of a conformational change in the enzyme.

Amino Acid Sequence↗
PubMed2000

Development of a tool to measure clinical competence in occupational therapy: a pilot study?

Clinical competence is generally defined as a combination of knowledge, skill and professional behaviour. It is typically assessed using written tests, direct observation, chart audit, client satisfaction surveys and supervisor ratings. This paper describes the development and evaluation of a chart-stimulated recall (CSR) measure that combines the methods of chart audit and clinician interview to assess the clinical competence of practicing occupational therapists. The CSR tool was developed using the Canadian Guidelines for Client-Centred Practice and taps global domains of competence: use of theory, assessment, program planning, intervention, discharge planning, follow-up, program evaluation, clinical reasoning and professional behaviours. This pilot study involved two independent raters/interviewers who assessed twelve occupational therapy clinicians on two occasions using a random sample of client cases/records on each occasion Results indicate that the CSR tool is not only reliable and valid, but also sufficiently generic to be used in a variety of practice settings as a global measure of on-the-job performance.

Canada↗
PubMed2000

What happens to special hospital patients admitted to medium security?

This article describes the outcome of all the Special Hospital patients admitted to and discharged from the Norvic Clinic over a period of ten years since its opening in 1984. This study identified 23 patients. Of those transferred, 56% had a legal classification of mental illness. A much higher percentage (91%) were restricted under the powers of s.41 of the Mental Health Act 1983, compared to 69% in the West Midlands study (Cope and Ward, 1993). There appears to be a significant difference between the mental disorder groups for age on admission to Special Hospital when considering all patients (males and females). This difference is not maintained when males and females are looked at separately, although the result for males is nearly significant (p = 0.0606). The number of female patients is small (five) and so the tests will hardly be reliable for the female sample. No significant differences were demonstrated for any of the other variables considered. Like the West Midlands study, minor reconvictions were completely absent. This was an unusual finding within the West Midlands study and not replicated from any of the previous Special Hospital studies. In this study, failure constituted an unsuccessful transfer with return to Special Hospital and reconviction. The percentage of those returned to Special Hospital without reaching the community was slightly lower than the West Midlands study, for both the mentally ill and those classified as suffering from psychopathic disorder.

Adolescent↗
PubMed2000

Prenatal drug exposure and social policy: the search for an appropriate response.

Prenatal drug exposure continues to be a controversial topic. Views of what constitutes an appropriate response to drug-exposed infants vary, in large part due to the many complex issues endemic to perinatal substance use. The purpose of this article is to review the controversy surrounding prenatal drug exposure, outline the policy dilemmas that complicate attempts to respond appropriately, review current practice in this area and the effectiveness of those practices, and offer specific recommendations as a starting point for debate. It is suggested that earlier controversy regarding the sequelae of prenatal drug exposure may be decreasing as research identifies specific and subtle deficits in some affected infants. It is also suggested that the postnatal effects of parental substance abuse (e.g., in terms of abuse/neglect, attachment, and development) are the more appropriate focus of child protection efforts, and that different disciplines must collaborate to reach a consensus regarding the nature of these efforts.

Child↗
PubMed2000

The prevalence of urethral infections amongst asymptomatic young men in Hat Yai, southern Thailand.

The aim of this study was to survey sexual behaviour and estimate the prevalence of urethral infections amongst male vocational college students. A cross-sectional survey was performed among 479 young men attending 2 vocational colleges in Hat Yai, southern Thailand. Polymerase chain reaction (PCR) tests of first-void urine (FVU) samples were used to detect infection with Chlamydia trachomatis, Neisseria gonorrhoeae, Ureaplasma urealyticum, Mycoplasma genitalium and Mycoplasma hominis. Girlfriends were the usual sexual partners for 89% of men with only 11% regularly patronizing sex workers. Condom usage was low. The prevalence of any urethral infection was 15.9% with: C. trachomatis 4%, N. gonorrhoeae 0.2%, U. urealyticum 10.9%, M. genitalium 2.3% and M. hominis 1.3%. Infection with more than one organism was found in 2% of men. While the prevalence of infection with chlamydia or gonorrhoea was relatively low, the prevalence of 'any urethral infection' was moderately high and suggests that unprotected sexual intercourse is commonly occurring. As girlfriends were the most usual sexual partners, they must be at significant risk of pelvic infection. There is a need for programmes targeting this group of people.

Adolescent↗
PubMed1999

Identification of human complement Factor H as a ligand for L-selectin.

The selectin family of adhesion molecules (E-, P- and L-selectins) is involved in leukocyte recruitment to sites of inflammation and tissue damage. Recently it has been shown that L-selectin is involved not only in leukocyte tethering and rolling, but also plays an important role in leukocyte activation. For example, glycosylation-dependent cell-adhesion molecule 1 (GlyCAM-1), a known ligand for L-selectin, has been shown to enhance beta2-integrin function. GlyCAM-1 is a secreted protein and is present in mouse serum at a concentration of approx. 1.5 microg/ml. There is no obvious GlyCAM-1 homologue in man and, to date, L-selectin ligand(s) from human serum have not been characterized. Therefore we have used L-selectin affinity chromatography, followed by ion-exchange chromatography, to isolate specific ligand(s) for L-selectin. Using this procedure, we have isolated three major glycoproteins of apparent molecular masses 170 kDa, 70kDa and 50 kDa. The 170 kDa protein band was digested with trypsin and peptides were analysed by delayed extraction matrix-assisted laser desorption ionization MS and protein database searching. The 170 kDa protein was identified as the human complement protein Factor H. Human Factor H, isolated by a different method, was shown to bind specifically to L-selectin in the presence of CaCl2, and binding was inhibited by anti-L-selectin antibodies, fucoidan and lipopolysaccharide. Only a part of the purified Factor H preparation bound to immobilized L-selectin. The interaction of Factor H with leukocyte L-selectin was shown to induce the secretion of tumour necrosis factor-alpha (TNF-alpha). Pretreatment of Factor H with sialidase reduced both the binding of L-selectin to Factor H and the Factor H-induced L-selectin-mediated TNF-alpha secretion by leukocytes. Taken together, these results demonstrate that a post-translationally modified form of human plasma Factor H is a potential physiological ligand for L-selectin.

Blood Proteins↗
PubMed1999

Up-regulation of amphotrophic retroviral receptor expression in human peripheral blood CD34+ cells.

Retroviral-mediated gene transfer into hematopoietic stem cells provides the only means of stable transduction of these cells and their progeny for use with a variety of potentially therapeutic genes. Expression of the Moloney amphotropic retroviral receptor-pit-2 or GLVR-2-is critical to the recognition and entry of Moloney leukemia virus-derived viruses into human target cells such as CD34+ hematopoietic cells. GLVR-2 functions as a sodium-dependent phosphate transporter as well as a receptor. We have previously shown that the expression of the murine homologue of the amphotropic receptor Ram 1, also a phosphate transporter, is developmentally regulated in murine hematopoietic fetal liver cells. We also demonstrated that culture of murine fetal liver cells in phosphate-free (PO(4)-free) medium increases levels of receptor mRNA and makes murine fetal liver cells susceptible to Moloney amphotropic viral gene transfer. We now examine the effect of culture conditions on the expression of GLVR-2 in human CD34+ cells. In this report, we demonstrate that there is a 2-3 fold increase in GLVR-2 mRNA levels in CD34+ cells after 3 days in culture with interleukin 3, interleukin 6, and stem-cell factor. In addition, the use of PO(4)-free medium increases expression of GLVR-2 an additional 2-fold in these cells during this time. These results indicate that GLVR-2 expression can be up-regulated on these cells, and may permit improved retroviral gene transfer efficiencies.

Animals↗
PubMed1999

Competitive repopulation of retrovirally transduced haemopoietic stem cells.

Gene transfer into haemopoietic stem cells (HSC) may be useful in gene therapy for a variety of inherited and acquired human diseases. Cell division is required for retroviral transduction, and cytokine stimulation is often used to increase mitosis of quiescent HSC. Exposure to cytokines has been shown to have an unfavourable effect on the engraftment of these cells when competed with unmanipulated HSC. We now show that a similar engraftment defect is present when HSC are manipulated and transduced with the human multiple drug resistance (MDR) gene. The extent of the unfavourable competition depended on the relative numbers of cytokine-treated and fresh cells when the two populations of cells were administered simultaneously into marrow-ablated isogenic mice. When the manipulated transduced cells were given 2 or 4 d before the unmanipulated cells there was a much greater engraftment of the manipulated cells. The data suggested that the manipulated cells were at a relative disadvantage for marrow engraftment as compared to fresh cells, presumably due to the more efficient homing and engraftment properties of these latter unmanipulated cells. However, the manipulated cells had no intrinsic inability to engraft when they were the predominant donor cell population. In all cases the percent of MDR transduced cells in the engrafting manipulated cells remained relatively constant at about 25-30%. These results have implications for the use of manipulated transduced stem cells in gene therapy, suggesting that administering them before adding fresh cells can overcome their engraftment defect.

Animals↗
PubMed1999

Comparison of Adsol and CPDA-1 blood preservatives during simulated massive resuscitation after hemorrhage in swine.

BACKGROUND: In recent years, there has been a change from the use of blood stored in CPDA-1 to the use of red cells (RBCs) stored in electrolyte mixtures, such as Adsol (AS-1 RBCs). However, because Adsol contains mannitol, as well as increased amounts of glucose relative to CPD and CPDA-1, concerns have been expressed as to possible harmful effects (recipient hyperglycemia, inappropriate osmotic diuresis) that it might induce under conditions of massive RBC transfusion. STUDY DESIGN AND METHODS: A hemorrhagic shock animal model was used to evaluate the effects of large-volume infusion of CPDA-1 or Adsol on glucose homeostasis and on urinary output under conditions that were devoid of extensive surgical manipulation. Hemorrhage was induced in 10 female Pitman-Moore mini-pigs to maintain mean arterial blood pressure at 55 mmHg for 90 minutes. After the return of autologous RBCs plus 1 L of 0.9-percent sodium chloride, the animals were given solution equivalent to the solute load in either 20 units of CPDA-1 whole blood (63 mL x 20 = 1260 mL) or 20 units of AS-1 RBCs (100 mL x 20 = 2000 mL) over a period of 90 minutes. Animals were monitored to determine physiologic and blood chemical responses to infusion of the solutions and to determine if there was hyperglycemia or inappropriate diuresis in the Adsol-treated group. RESULTS: Animals that received CPDA-1 developed significant hypocalcemia, arterial hypotension, and elevated blood glucose concentrations; two of five animals died of circulatory collapse. In contrast, glucose metabolism in the Adsol recipients was well-regulated, serum ionized calcium concentration was not significantly altered, and all animals survived. No evidence of inappropriate diuresis was observed. CONCLUSION: Administration of large amounts of Adsol was not associated with hyperglycemia or inappropriate osmotic duiresis in hemorrhaged and resuscitated minipigs. These data suggest that fewer physiologic changes may be associated with the massive transfusion of AS-1 RBCs than with that of CPDA-1 whole blood.

Adenine↗
PubMed1999

Risk factors for coronary heart disease and acute-phase proteins. A population-based study.

AIMS: Circulating levels of C-reactive protein and serum amyloid A protein increase markedly, and albumin levels fall, during the acute-phase response to tissue injury, infection and inflammation. Some acute-phase proteins have been associated with increased risks of coronary heart disease in long-term prospective studies. The aim of the present study was to determine whether circulating concentrations of C-reactive protein, albumin and serum amyloid A protein are correlated with one another, standard vascular risk factors, markers of persistent infection, or indicators of socio-economic status. METHODS AND RESULTS: We report a cross-sectional study of 704 individuals without a history of coronary heart disease from five general practices in Bedfordshire, U.K. Plasma levels of C-reactive protein and serum amyloid A protein were strongly associated with each other (2 P<0.00001) and inversely related to levels of serum albumin (2 P<0.00001). There were highly significant associations of plasma C-reactive protein concentrations with cigarette smoking and obesity (2 P<0.00001 for each). Serum albumin levels were strongly associated with blood pressure (2 P<0.0001) and plasma lipids (2 P<0.001), and concentrations of serum amyloid A protein were strongly correlated with obesity (2 P<0.0001). CONCLUSION: Previously reported long-term prospective studies have found an increased risk of coronary heart disease of about 50% in people with raised baseline levels of plasma C-reactive protein or low albumin. The strong cross-sectional associations we have found between levels of these proteins with each other and with concentrations of serum amyloid A protein suggest that some underlying process related to inflammation is likely to be of relevance to the causation of disease. Further studies are needed to determine if the strong associations of plasma levels of C-reactive protein with cigarette smoking and obesity indicate that this particular protein can mediate some of the effects of those risk factors on coronary heart disease.

Acute-Phase Proteins↗
PubMed1999

Purification and characterization of a complex from placental syncytiotrophoblast microvillous membranes which inhibits the proliferation of human umbilical vein endothelial cells.

The signs of pre-eclampsia are thought to arise from maternal endothelial dysfunction caused by circulating factors of placental origin. Syncytiotrophoblast microvillous membranes (STBM) cause endothelial disruption and inhibit proliferation in vitro. Significantly increased amounts of STBM can be detected in blood from pre-eclamptic women and could contribute to endothelial dysfunction in vivo. This study purified a complex from STBM which inhibits the proliferation of cultured human endothelial cells. Integral membrane proteins were solubilized with sucrose monolaurate. Anion exchange chromatography yielded two peaks of anti-proliferative activity. Only the second peak was specific to STBM and was subjected to further separation by Sephacryl S-200 gel filtration chromatography (GFC). A single peak of specific activity eluted close to the void volume, at a position unaltered by added denaturing agents, guanidium chloride or urea. On Sephacryl S-300 GFC, two peaks were obtained of 410 and 820 kDa, with similar anti-proliferative activity and protein components (by SDS-polyacrylamide gel electrophoresis). The major protein bands were as integrins alpha5 and alpha v, dipeptidyl peptidase IV, alpha-actinin, transferrin, transferrin receptor, placental alkaline phosphatase and monoamine oxidase A.

Actinin↗
PubMed1999

Ultrasound-induced cell lysis and sonoporation enhanced by contrast agents.

The enhancement of ultrasound-induced cell destruction, lysis, and sonoporation in low cell concentration suspensions (2 x 10(5)/mL) by the presence of contrast agents (gas bubble to cell ratio = 230) was demonstrated using cervical cancer cells (HeLa S3) suspensions containing micron-size denatured albumin microspheres filled with air (Albunex) or octafluoropropane (Optison). The suspensions were insonificated by 2-MHz continuous or tone burst ultrasound in near field. The spatial peak-pressure amplitude was 0.2 MPa. The enhancement of cell destruction due to Optison was shown to be much higher than that due to Albunex for similar bubble concentration and ultrasound conditions. For tone burst exposures, significant lysis and sonoporation only occurred in the presence of a contrast agent. The majority of the bioeffects observed occurred in the first 5 min of exposure. The relationship between the enhancement of bioeffects and duty cycle of tone burst ultrasound appears to indicate that both stable gas spheres of contrast agents and cavitation nuclei created by the disruption of the gas spheres play a significant role in causing the bioeffects.

Cell Death↗
PubMed1999

Chronic infection with Helicobacter pylori, Chlamydia pneumoniae, or cytomegalovirus: population based study of coronary heart disease.

OBJECTIVE: To study possible associations between coronary heart disease and serological evidence of persistent infection with Helicobacter pylori, Chlamydia pneumoniae, or cytomegalovirus. DESIGN: Population based, case-control study, nested within a randomised trial. SETTING: Five general practices in Bedfordshire, UK. INDIVIDUALS: 288 patients with incident or prevalent coronary heart disease and 704 age and sex matched controls. RESULTS: High concentrations of serum IgG antibodies to H pylori were present in 54% of cases v 46% of controls, with corresponding results for C pneumoniae seropositivity (33% v 33%), and cytomegalovirus seropositivity (40% v 31%). After adjustments for age, sex, smoking, indicators of socioeconomic status, and standard risk factors, the odds ratios (95% confidence intervals) for coronary heart disease of seropositivity to these agents were: 1.28 (0.93 to 1.75) for H pylori, 0.95 (0.66 to 1.36) for C pneumoniae, and 1.40 (0.96 to 2. 05) for cytomegalovirus. CONCLUSIONS: There is no good evidence of strong associations between coronary heart disease and serological markers of persistent infection with H pylori, C pneumoniae, or cytomegalovirus. To determine the existence of moderate associations between these agents and disease, however, larger scale studies will be needed that can keep residual confounders to a minimum.

Adult↗
PubMed1999

Atypical C-ANCA following high dose intravenous immunoglobulin.

AIMS: (1) To assess a range of intravenous immunoglobulin products for atypical classical antineutrophil cytoplasmic antibody (C-ANCA) staining and to determine if this is present in patients treated with high dose intravenous immunoglobulin (2 g/kg/month) and replacement doses (200 mg/kg fortnightly); (2) using the United Kingdom national external quality assessment scheme (NEQAS), to determine if laboratories could differentiate this pattern from classical ANCA. METHODS: ANCA testing was performed on 30 batches of intravenous immunoglobulin from several manufacturers. Six patients treated with high dose intravenous immunoglobulin and 11 receiving replacement doses of immunoglobulin for hypogammaglobulinaemia were tested for ANCA by indirect immunofluorescence on cytospin preparations of ethanol fixed neutrophils and by enzyme linked immunosorbent assay (ELISA). One of the positive immunoglobulin batches was tested blindly by 125 laboratories involved in NEQAS by indirect immunofluorescence and by ELISA in some laboratories. RESULTS: 16 of 31 batches of intravenous immunoglobulin from six different manufacturers were atypical C-ANCA positive. Three of six patients receiving high dose intravenous immunoglobulin and none of 11 patients on replacement doses were atypical C-ANCA positive. The results of the NEQAS assessment by indirect immunofluorescence were 68% C-ANCA positive, 17% negative, 9% atypical C-ANCA, and 6% P-ANCA. CONCLUSIONS: Some but not all intravenous immunoglobulin products yield a positive atypical cANCA by indirect immunofluorescence. An identical pattern may be observed in patients receiving high dose intravenous immunoglobulin but not in those on replacement doses. Of laboratories participating in NEQAS, 68% reported this pattern as cANCA. This reinforces the importance of reporting only "classical ANCA," defined by international ANCA workshops, to maintain the specificity of ANCA immunofluorescence and its close disease associations.

Agammaglobulinemia↗