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Biomedical subjects

P Holt

Publications and source records attributed to P Holt.

At least 37 records · Page 2Linked to original sources
PubMed1994

Consistent occurrence of hemagglutinin variants among avian influenza virus isolates of the H7 subtype.

Several field isolates of avian influenza virus of the H7 subtype were analyzed for the presence of hemagglutinin variants by labeling proteins in cells infected with virus clones, and reacting with monoclonal antibodies. Each strain was shown to contain two distinct electrophoretic variants of the uncleaved hemagglutinin. In the A/Tk/Ore/71 (H7N3) isolate, two variants remained in the population through 35 laboratory passages, indicating both are stable and may be important to expression of the viral phenotype. Nucleotide sequence analysis of the HA gene of these two variants demonstrated differences at several amino acid positions in the HA1 subunit including one glycosylation site. Three additional recent North American isolates were also each found to contain two electrophoretic variants occurring within populations as few as one embryo passage away from the original clinical specimen. Pulse-chase assays indicated none of the variant HA molecules were cleavable in chick embryo fibroblasts. In the highly pathogenic Australian isolate; A/Ck/Victoria/75, both HA variants are cleavable in fibroblasts, without added trypsin, and the differences are localized within the HA1 region. With all the strains tested, the slower migrating HA variant was associated with a consistently higher hemagglutinin titer in embryos. Finally, recent H7 isolates from imported birds (A/Soft Bill/Ill/92) also exhibit similar variants, indicating their occurrence is not limited to domestic poultry. This consistent presence of two distinct electrophoretic variants in several avian H7 isolates suggests multiple allelic forms of the H7 hemagglutinin.

Animals↗
PubMed1994

Purification and characterization of mannan-binding protein from mouse serum.

Mouse mannan-binding protein (MBP) was identified in serum by its Ca(2+)-dependent binding to mannan. On gel permeation chromatography, the protein eluted corresponding to a molecular weight of approximately 750 kDa. Analysed on SDS-PAGE under reducing conditions, the polypeptide showed an apparent molecular weight of 28 kDa, while several high molecular weight bands were seen under non-reducing conditions. The presence of collagen-like domains within the molecule was indicated by a high glycine content (14.9%) and substantiated by sensitivity to collagenase. Rabbit anti-mouse MBP antisera were raised. The concentration of MBP in serum from normal mice was measured by rocket immunoelectrophoresis and found to be from below 1 microgram/ml to 100 micrograms/ml (average 50 micrograms/ml, n = 60). The binding of mouse MBP to mannan could be inhibited by mono- and disaccharides in the following order of potency: L-fucose > D-mannose > N-acetyl-D-glucosamine > maltose > D-mannoheptulose > D-glucose > N-acetyl-D-mannosamine >> lactose > D-galactose >> N-acetyl-D-galactosamine. Mouse MBP was shown to activate the classical complement cascade after binding to mannan. The sequence of 14 NH2-terminal amino acid residues of the molecule showed 93% identity to rat MBP-A and complete identity to the translated cDNA sequences for mouse MBP-A and mouse Ra-reactive factor component P28b (RaRF P28b) published previously. The amino acid composition of mouse MBP showed a high degree of homology to MBPs from other species and mouse RaRF P28b.

Amino Acid Sequence↗
PubMed1994

Hansen's disease. Practice tips for management.

The author highlights some of the critical features of general practice diagnosis and management of Hansen's disease in First World primary care practice. These features are often not obvious or emphasised in most texts because they are designed for a Third World scenario, where primary care is delivered without the luxury of medically trained practitioners and therefore without the option of emergency steroid therapy.

Family Practice↗
PubMed1993

High-performance liquid chromatography of amino acids, peptides and proteins. CXXIX. Ceramic-based particles as chemically stable chromatographic supports.

Porous zirconia based particles have been modified using different derivatisation procedures. The modified particles were characterised in terms of their accessible surface areas and degree of surface coverage of the bounded or physicoated phases utilising the strong and specific adsorption of phosphate ions to the zirconia surface. The hydroxyl group density was determined by a 1H NMR technique. The particles were modified by immobilising different silanes to introduce either hydrophobic ligands or reactive groups onto the zirconia surface. In the latter case, various ligands were then covalently attached to the activated supports. Using this type of modification, n-octadecyl- (C18), carbohydrate- and Cibacron Blue F3GA-modified zirconia particles were produced. Furthermore, polymeric coated particles were prepared either by using polybutadiene or by cross-linking the carbohydrate modified sorbents. The pH stability of the different sorbents were determined in batch experiments and under chromatographic conditions. The leakage of ligands was monitored by UV absorption and by employing radioactively labelled ligands. The performance of the C18 reversed-phase modified zirconia in packed columns was also used as an indicator of changes in the surface chemistry following pH stability tests. The experimental results indicate that the Cibacron Blue F3GA dye-modified sorbent was stable up to pH 10.5, the C18 reversed-phase packing up to pH 13 and the carbohydrate-bonded phase up to pH 12. These investigations substantiate the favourable chemical and physical characteristics anticipated for surface modified zirconias for potential use as chromatographic adsorbents.

Carbohydrates↗
PubMed1993

Purification and characterization of bovine mannan-binding protein.

Bovine mannan-binding protein (bMBP) was observed in serum by its Ca(2+)-dependent binding to mannan and by an M(r) of 28 kDa under reducing conditions on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The lectin was isolated by precipitation with polyethyleneglycol (PEG), affinity chromatography on mannan-Sepharose eluted with EDTA, and absorption on Sepharose 4B rabbit anti-bovine Ig to remove anti-mannan antibodies. Fractions containing the lectin were reapplied to mannan-Sepharose and eluted first with N-acetyl-D-glucosamine (GlcNAc) to remove conglutinin, and then with mannose to elute the 28 kDa lectin. Further purification was achieved by ion-exchange chromatography on Mono-Q and by mannose-gradient elution from a mannan-Sepharose column. SDS-PAGE of the purified lectin showed three high molecular weight bands under non-reducing conditions. The reduced protein gave a single band of 28 kDa. On gel permeation chromatography under non-dissociating conditions, the protein emerged at a volume corresponding to M(r) approximately 750 kDa. Amino acid analysis showed the presence of hydroxyproline and hydroxylysine, and a high glycine content (17.7%), suggesting the presence of a collagen-like structure. This was supported by the susceptibility of the protein to collagenase digestion. The N-terminal 26 amino acids showed 62% identity with human MBP, when three gaps were allowed in the alignment.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Evaluation of a cognitive-behavioural intervention for HIV prevention among injecting drug users.

OBJECTIVE: To evaluate the effectiveness of relapse prevention (RP) and brief intervention (BI) in reducing HIV risk-taking behaviours among injecting drug users (IDU) enrolled in methadone programmes. The hypotheses tested were: (1) that a six-session RP programme would be more effective in reducing HIV risk-taking behaviours than a one-session BI and a non-intervention control condition (C); and (2) that BI would be more effective in reducing HIV risk-taking behaviours than C. DESIGN: Clients of methadone programmes were randomly assigned to either RP, BI, or C. Follow-up occurred 6 months after pre-intervention assessment and was conducted by independent research assistants who were not aware of subjects' group allocations. SETTING: Confidential assessment interviews and interventions generally took place at the methadone unit treating the subject. PARTICIPANTS: Ninety-five IDU enrolled in methadone programmes. Study entry criteria were: injection of any drug in the 6 months before the day of pre-intervention assessment; literacy in English; agreement to HIV-antibody testing for research purposes; and no known diagnosis of a serious mental illness. Eighty subjects were contacted successfully for a 6-month follow-up. INTERVENTIONS: The RP intervention was a six-session programme. Each 60-90 min session was conducted individually. The BI was a one-session motivational interview lasting 60-90 min, accompanied by a self-help booklet. MAIN OUTCOME MEASURES: All subjects were administered the Drug Use Scale and HIV Risk-Taking Behaviour Scale of the Opiate Treatment Index and consented to the collection of a capillary blood sample for HIV-antibody testing at pre-intervention assessment and follow-up. At follow-up, the Highest HIV Risk-Taking Behaviour Scale, collateral reports from subjects' sexual partners pertaining to the previous month and urinalysis results for the month before follow-up were collected. RESULTS: Compliance with interventions was good. Correspondence of self-reports with urinalysis and collateral reports was satisfactory. There were no significant differences between groups in risk-taking behaviours during the month before follow-up. However, there was evidence of a lower rate of needle-risk behaviour (sharing and cleaning) during the heaviest risk-taking month since pre-intervention assessment in the group given RP. There were no indications that BI was of greater benefit than the usual methadone treatment and neither intervention appeared to reduce sexual risk behaviour. CONCLUSIONS: The results are cautiously interpreted as showing that individual RP programmes decrease the level of needle-risk behaviour during relapse episodes, but further research is required to replicate this finding.

Adolescent↗
PubMed1991

[Indicators of coronary risks--attitude, knowledge and behavior. An interview study among 917 men and women aged 25-44 years].

The purpose of this study was to clarify whether there was any agreement between knowledge about coronary risk factors, attitudes to individual prevention of coronary heart disease and preventive health behaviour. In particular the differences between males and females were examined. A total of 749 persons ranging in age between 25 and 44 (that is 82% of a random group of 917 persons) were interviewed in this cross sectional study. Physical inactivity, smoking and fat consumption were used as behaviour related risk factors. Generally, young adult Danes had a poor knowledge and poor health behaviour related to coronary heart disease in spite of their positive attitudes towards prevention. The study indicated that neither attitudes nor knowledge were correlated to preventive health behaviour. Women had better health behaviour patterns than men despite the same amount of knowledge and attitudes. In the above mentioned connexions, men showed positive correlation while no correlation existed for women.

Adult↗
PubMed1991

Immunosuppressive effects of Fusarium moniliforme corn cultures in chickens.

In the present study, the toxic and immunosuppressive effects of three isolates of Fusarium moniliforme (MRC 826, MRC 1069, and RRC 408) in male White Leghorn chickens were investigated. Chickens were fed diets containing .5, 5.0, or 25% of F. moniliforme corn cultures for 6 wk. About 30% of the chickens fed RRC 408 had leg weakness. Relative weights of bursae of Fabricius were lower in birds fed all doses of MRC 826. Birds fed 5.0 or 25% MRC 1069 had lower relative spleen weights. Thymus weights were lower in birds fed .5 and 5.0% RRC 408, but not in those fed 25%. Immunosuppressive effects were determined by measuring serum levels of primary and secondary agglutinin responses to SRBC and Brucella abortus. Birds fed 5.0 or 25% MRC 826 were immunosuppressed, as shown by low antibody titers to B. abortus in both the primary and secondary responses. Isolate MRC 1069 caused a decrease in secondary response to SRBC at 25% and B. abortus at the 5.0 and 25% of culture material. The RRC 408 isolated reduced the secondary response to SRBC at all doses and response to B. abortus at 5.0 and 25% of culture material. These results appear to be the first report that feed contaminated with F. moniliforme can produce deficiencies in the immune system of chickens.

Animals↗
PubMed1990

Acceleration of conduction within an accessory pathway with propafenone.

We describe a case of dangerous acceleration of conduction through an accessory pathway produced by the Class IC agent propafenone during routine electrophysiological study of a patient with Wolff-Parkinson-White syndrome. This pro-arrhythmic effect has not previously been described with this drug. Propafenone is now being more widely used since the publication of the preliminary results of the CAST Study in the U.S.A.

Adult↗
PubMed1990

T cell reactivity to the purified mycobacterial antigens p65 and p70 in leprosy patients and their household contacts.

T cell reactivity to the 70 and 65 kD (p70 and p65) protein antigens derived from Mycobacterium bovis BCG strain was studied by measuring the proliferative responses of peripheral blood mononuclear cells from members of an isolated Aboriginal community resident in the Torres Straits islands. In the nine index leprosy cases the pattern of responsiveness to the purified antigens paralleled that to whole sonicates from M. leprae and BCG. In the 40 contacts of the index cases, a high correlation was observed between the responses to p70 and p65 as well as to the crude sonicates. Significant T cell responses to the purified antigens, as well as the crude sonicates, were obtained with cells from the majority of contacts. Limiting dilution analysis of precursor frequencies in the contacts confirmed the immunogenicity of the purified antigens and excluded both a mitogenic component and the presence of suppressor cells in those moderate or low responders whose blood contained sufficient precursors to be tested. p70 appeared to be more potent in stimulating a proliferative response than p65 at equivalent protein concentrations. No correlation between responder status to either antigen and disease type was detected in families. These findings provide confirmation of the importance of p70 and p65 as major T cell immunogens in man and indicate that they are both potential candidates for inclusion in a bivalent vaccine for leprosy and tuberculosis.

Antigens, Bacterial↗
PubMed1990

Inappropriate discharges by the implantable cardioverter defibrillator during postoperative testing: implications for intraoperative assessment.

Inappropriate shocks were delivered to a patient while in sinus rhythm by an implantable cardioverter defibrillator (ICD) during routine prehospital discharge testing. This was induced by the standard programmer when the "read" telemetry sequence was initiated. The ICD was removed and found to suffer from electrical artifact that was sensed as ventricular tachycardia during telemetry. To avoid inadvertent telemetry-induced shocks during routine testing, all ICDs should be interrogated, using a standard programmer, intraoperatively, with the unit in "defibrillation on" mode.

Aged↗
PubMed1990

Evidence for a general neurotic syndrome.

Neurotic syndromes are defined by characteristic patterns of symptoms, but the validity of the distinction between one syndrome and another depends on associations between the syndromes and clinical history, or treatment response factors that are independent of the defining phenomena. In both a group of twin volunteers and a group of patients with panic disorder/agoraphobia, the lifetime experience of more than one diagnosis of a neurotic syndrome was common but there was no evidence of patterns of co-occurrence of diagnoses being associated with particular syndromes. Receiving a diagnosis was associated with abnormal scores on measures of neuroticism and locus of control, the extent of the abnormality increasing with the number of different diagnoses satisfied. It is argued that the concept of a general neurotic syndrome depends in part on the presence of such predisposing personality factors, and that reduction in this predisposition to neurosis should be the focus of treatment.

Adolescent↗