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Biomedical subjects

B Griffin

Publications and source records attributed to B Griffin.

At least 73 records · Page 4Linked to original sources
PubMed1986

Factors predictive of early angiographic and functional success following percutaneous transluminal coronary angioplasty.

Baseline variables in 300 coronary angioplasty procedures were analysed to identify factors predictive of a successful outcome. Separate multivariate analyses distinguished between predictors of primary angiographic success and functional success as determined by the results of predischarge treadmill stress electrocardiography. Three independent predictors of primary angiographic success were identified: number of balloon inflations per procedure, initial stenosis, and operator experience. Of these, the number of balloon inflations per procedure and operator experience were also predictive of functional success, reflecting the dependence of a good functional result on a successful procedure. Other independent predictors of functional success were the severity of the residual stenosis and single vessel coronary artery disease suggesting that adequacy of revascularization is an important determinant of the functional result. These data illustrate the interaction between clinical, angiographic and functional variables in determining the success of PTCA. A good angiographic result may not translate into a good functional result if revascularization is incomplete.

Adult↗
PubMed1986

Early results after percutaneous transluminal coronary angioplasty in 400 patients.

In a consecutive series of 400 patients treated by percutaneous transluminal coronary angioplasty 212 had single vessel disease, 142 had multivessel disease with only one vessel dilated, and 46 had multivessel dilatation. In addition sequential stenoses were dilated in the same vessel in all groups. There was no mortality among patients with single vessel disease. Success rates varied from 83% to 90% according to the artery in which angioplasty was attempted. Urgent surgery was required by 3.8%. Primary success was lower (74%) in the presence of multivessel disease and complications were more frequent, with four deaths (2.8%). In 46 patients with multivessel disease in whom all important lesions were dilated during the same procedure the overall primary success rate was 76% and within the last year of the study it was 91%. One (2%) patient died and three (7%) required urgent surgery. Twelve (86%) out of 14 stenosed vein grafts were successfully dilated and eight (53%) chronically occluded vessels were re-opened; in both groups there were no deaths, no infarctions, and no need for urgent surgery. In all groups symptoms improved greatly and predischarge exercise tests showed that there was no reversible ischaemia in 94% of patients with single vessel disease or in 65% of patients with incomplete revascularisation. Six months after the procedure 95% of the patients had improved symptomatically and 80% had normal exercise tests after one year. Percutaneous transluminal coronary angioplasty is the method of choice in single vessel disease and its use also results in a high proportion of other patients becoming symptom free. Complication rates are low and for selected patients results that are equivalent to those of cardiac surgery are obtained.

Adult↗
PubMed1986

The innovative rehabilitation team: an experiment in team building.

This article describes an effort by one rehabilitation team to create innovative approaches to team care in a medical rehabilitation hospital. The major arena for implementing change was the weekly patient rounds. We worked to increase patient involvement, developed a rounds coordinator role, used a structured format, and tried to integrate research findings into team decision making. Other innovations included use of a preadmission questionnaire, a discharge check list, and a rounds evaluation questionnaire. The impact of these changes was evaluated using the Group Environment Scale and by analyzing participation in rounds based on verbatim transcripts obtained prior to and 20 months after formation of the Innovative Rehabilitation Team (IRT). The results showed decreased participation by medical personnel during rounds, and increased participation by patients. The rounds coordinator role increased participation rates of staff from all disciplines and the group environment improved within the IRT. These data are compared with similar evaluations made of two other groups, which served as control teams. The problems inherent in making effective, lasting changes in interdisciplinary rehabilitation teams are reviewed, and a plea is made for other teams to explore additional ways to use the collective creativity and resources latent in the team membership.

Decision Making↗
PubMed1984

Studies on the procurement of coagulation factor VIII: selective precipitation of factor VIII with hydrophilic polymers.

Early work on the purification of factor VIII using polyethylene glycol (PEG) indicated that other polymers might also be used to precipitate factor VIII leaving fibrinogen in solution. Recently polyvinylpyrrolidone (PVP) has also been advocated for this purpose. In this study, different concentrations and molecular weights of hydroxyethyl starch, dextran, PEG, PVP, Ficoll, Percoll and albumin were examined for their ability to precipitate the factor VIII complex from cooled (not frozen) fresh CPD plasma. At optimal concentrations near quantitative recovery of VIIIR:Ag and VIII:CAg was achieved in 2 hr with minimal precipitation of fibrinogen or total protein. The best separations were observed with hydroxyethyl starch, albumin or Ficoll. PVP and PEG gave inferior purifications. Results for cryoprecipitate and intermediate-purity factor VIII concentrate were inferior to those obtained with plasma. Simple pre-concentration of plasma prior to chilling is an attractive alternative for large scale continuous production.

Chemical Precipitation↗
PubMed1983

The interaction between collagens and factor VIII/von Willebrand factor: investigation of the structural requirements for interaction.

The blood protein Factor VIII/von Willebrand factor (FVIII/VWF) has been shown to bind to a variety of collagen polymers including (i), the native-type fibres (of collagens types I and III), (ii), segment-long-spacing (SLS) aggregates (of collagens types I, III, IV and V), (iii), the insoluble polymer obtained by random cross-linking of the type I monomer and (iv), the non-striated fibril (of type I) produced by alcohol precipitation. Relatively little binding of FVIII/VWF to the amorphous, non-fibrillar form of collagen (type I) produced by salt precipitation from acid solution was observed. No significant binding either to elastin or to the insoluble polymer derived by random cross-linking of bovine serum albumin was noted. The absorption of FVIII/VWF to collagens was affected by ionic concentration and FVIII/VWF was only totally bound at relatively low ionic strength. Binding of radiolabelled FVIII/VWF could be largely inhibited by an excess of the unlabelled protein. The interaction of FVIII/VWF with collagen fibres was inhibited in a concentration-dependent manner by monomeric collagen when present at relatively high concentrations. Gelatin did not appear to inhibit binding significantly. The structural requirements of collagen for binding to occur appear to resemble those required for collagen-induced platelet aggregation in which collagen quaternary structure rather than collagen type per se is the important factor. Loss of secondary or higher orders of structure of FVIII/VWF as a result of heat denaturation or reduction of disulphide bonds decreased or prevented binding. In accord with the association of biological activity with FVIII/VWF aggregates, optimal binding appeared to require the presence of aggregated FVIII/VWF.

Binding, Competitive↗
PubMed1982

The garden path.

Explore the source record for details and available documents.

Amino Acid Sequence↗
PubMed1981

Production of cryoprecipitate of intermediate purity in a closed system thaw-siphon process.

The thaw-siphon procedure for routine production of cryoprecipitate is described briefly, and also its extension to a reproducible procedure for production of cryoprecipitates of intermediate purity. For the latter, the average yield of factor VIII is 60% of that in the prefrozen plasma and approximately 30% is present in the supernatant plasma. The product contains 0.53 units of VIII: C per mg of total protein (of which about 70% is clottable). The mean value of the ratio VIII: C/VIII: RAG is about 0.7. The yield and purity of the product compare favourably with those reported for intermediate purity factor VIII concentrates produced by large-scale plasma fractionation laboratories. The procedure offers an alternative pathway to the production of factor VIII concentrate of intermediate purity and can be operated in any blood bank with a minimum of equipment.

Antigens↗
PubMed1981

Changes in factor VIII complex activities during the production of a clinical intermediate purity factor VIII concentrate.

Samples taken at various stages of preparation of intermediate purity factor VIII concentrate were assayed for factor VIII coagulant activity (VIII:C), factor VIII coagulant antigen (VIIIC:Ag) and factor VIII related antigen (VIIIR:Ag). The antigen results were used to assess mechanical loss during fractionation as these markers are relatively stable. In contrast VIII:C is sensitive to both mechanical and inactivation losses. The major loss of factor VIII occurred during the cryoprecipitation and extraction step and was due to both mechanical loss and inactivation. Losses before and after this step were largely due to inactivation of the factor VIII. Assay of VIIIR:Ag in concentrates presented problems and a modified technique is suggested.

Antigens↗
PubMed1978

Teaching medical students about treatment compliance.

Poor patient compliance is common in clinical practice but difficult to demonstrate to medical students in a convincing manner. To accomplish this, the authors asked medical students who preregistered for a conference on patient compliance to adopt the role of "patient" and to take "medication" (Vitamin C) for one week, to observe certain dietary restrictions, and to complete an attitude and health beliefs questionnaire. The educational impact was intensified by making prior predictions about outcome which were almost exactly confirmed. The predictions concerned failure to fill the prescription, extent and type of noncompliance, and significant differences in attitudes between compliant and noncompliant students. The attitudes of the students resembled those of noncompliant patients asked to take medication for nonsymptomatic disorders (such as hypertension). Those students who participated in the drug-taking experience rated the educational impact of the conference more highly than did those students who attended the conference but did not take part in the drug project.

Attitude to Health↗
PubMed1972

Characterization of strong polar mutations in a region immediately adjacent to the L-arabinose operator in Escherichia coli B-r.

Seven l-arabinose-negative mutations are described that map in three genetically distinct regions immediately adjacent to the araO (operator) region of the l-arabinose operon. All seven mutants revert spontaneously, exhibit a cis-dominant, trans-recessive polarity effect upon the expression of l-arabinose isomerase (gene araA), and fail to respond to amber, ochre, or UGA suppressors. Three of these mutants exhibit absolute polarity and are not reverted by the mutangens 2-aminopurine, diethyl sulfate, and ICR-191. These may have arisen as a consequence of an insertion mutation in gene araB or in the initiator region of the l-arabinose operon. The four remaining mutants exhibit strong but not absolute polarity on gene araA and respond to the mutagens diethyl sulfate and ICR-191. Three of these mutants are suppressible by two independently isolated suppressors that fail to suppress known nonsense codons. Partially polar Ara(+) revertants with lesions linked to ara are obtained from three of the same four mutants. These polar mutants, their external suppressors, and their partially polar revertants are discussed in terms of the mechanism of initiation of expression of the l-arabinose operon.

Arabinose↗