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Biomedical subjects

C A Ludlam

Publications and source records attributed to C A Ludlam.

At least 91 records · Page 5Linked to original sources
PubMed1995

Absence of hepatitis A virus transmission by high-purity solvent detergent treated coagulation factor concentrates in Scottish haemophiliacs.

Recent reports of hepatitis A virus (HAV) infection in haemophiliacs receiving high-purity solvent detergent (HP.SD) treated factor VIII concentrates have brought into question the efficacy of this virucidal method for inactivating HAV. To assess whether HAV may have been transmitted by HP.SD concentrates, we compared seroprevalence in haemophiliacs with different disease severity, sought evidence of seroconversion to HAV since introduction of HP.SD products, and directly examined concentrates for HAV RNA by PCR. Our data suggest that Scottish haemophiliacs are not being infected with HAV by HP.SD concentrates produced initially by CRTS Lille and presently by PFC Edinburgh and supplied by the Scottish National Blood Transfusion Service (SNBTS).

Adolescent↗
PubMed1995

A pharmacokinetic study of an ion-exchange solvent-detergent-treated high-purity factor VIII concentrate. Haemophilia Directors for Scotland and Northern Ireland.

An ion-exchange chromatography purified factor VIII concentrate (Liberate) that had undergone a solvent-detergent viral inactivation treatment was compared with an intermediate-purity concentrate (Z8), which was terminally heated at 80 degrees C for 72 h, in 15 haemophilia A patients in a blinded crossover pharmacokinetic study. Both products achieved a peak level close to that predicted (100 IU/dl for Liberate and 103 IU/dl for Z8) and there were no significant differences in the recoveries achieved nor of any of the other pharmacokinetic parameters. We conclude that the pharmacokinetic properties of factor VIII:C, following solvent-detergent treatment and ion-exchange chromatography, are equivalent to those of the lower purity terminally heat-treated product (Z8), and it is therefore likely to be a clinically efficacious concentrate.

Adult↗
PubMed1995

Osteolytic bone lesions in a patient with idiopathic myelofibrosis and bronchial carcinoma.

A 59 year old man with longstanding myelofibrosis and previous splenectomy was incidently found to have a large lytic lesion in his left femur which required operative fixation. He had undergone right upper lobectomy for squamous carcinoma of the bronchus five years earlier. Histological analysis of bone reamings showed no evidence of metastatic carcinoma. Osteosclerosis is frequently noted in patients with myelofibrosis but osteolytic lesions are uncommon and may be confused with metastatic malignancy.

Carcinoma, Bronchogenic↗
PubMed1995

Haemostatic effects of supraphysiological levels of testosterone in normal men.

The effects of exogenous testosterone on the haemostatic system were studied in a group of 32 healthy men undergoing a clinical trial of hormonal male contraception. The men received 200 mg testosterone oenanthate (TE) weekly i.m., and plasma samples were taken pretreatment, at defined time points up to 52 weeks of treatment, and 4 and 8 weeks after discontinuing TE. This dose of TE caused a 2-fold increase in trough plasma testosterone levels. TE caused a fall in plasma fibrinogen concentration after 16 weeks of treatment. This was sustained for the duration of TE treatment and recovered to pretreatment levels during the recovery phase. There was also a sustained fall in the level of C4b binding protein which showed a rebound to levels above pretreatment during recovery. Levels of antithrombin III and prothrombin fragment F1.2 rose initially during TE treatment, and levels of protein C, protein S (free) and plasminogen activator inhibitor fell, but the concentrations of these factors all returned to pretreatment levels during continued treatment. There was no change in the plasma concentrations of beta-thromboglobulin, tissue plasminogen activator, protein S (total), or D-dimer. There was a sustained increase in haemoglobin concentration and haematocrit, without any change in platelet count. The observed changes were consistent with mild activation of the haemostatic system during initial treatment with testosterone. After several months the raised activation markers had returned to pretreatment levels indicating that a new equilibrium had been established which did not appear to be prothrombotic.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Tissue-type plasminogen activator and plasminogen activator inhibitor activities as predictors of adverse events in unstable angina.

Among patients with recent-onset unstable angina and evidence of ischemia or coronary artery disease, the incidence of subsequent cardiovascular events is high. The aim of this study was to investigate, in this high-risk population, whether unstable angina was associated with abnormalities of tissue-type plasminogen activator (t-PA) or plasminogen activator inhibitor (PAI) activities and whether, in a prospective study, any of these parameters would identify patients with an adverse cardiovascular prognosis. A group of 22 high-risk patients with unstable angina (64% event rate at 3 months) was studied prospectively for 12 weeks, and the fibrinolytic parameters measured at presentation were related to subsequent cardiovascular progress. A group of 20 age- and sex-matched healthy subjects acted as control subjects. Patients who had subsequent cardiovascular events (acute myocardial infarction or severe recurrent angina +/- intervention) had significantly elevated PAI activity at presentation compared with both those who remained event-free (p < 0.05) or with control subjects (p < 0.02). In addition, basal activation of fibrinolysis was demonstrated in unstable angina at presentation; this persisted at 9 weeks in patients with a favorable outcome (p < 0.02 vs control subjects), whereas it was no longer evident in those who developed cardiac events. These findings suggest that measurements of t-PA/PAI activity may reflect the underlying pathophysiologic state and relate to subsequent cardiovascular events in unstable angina.

Aged↗
PubMed1994

Effects of captopril therapy on endogenous fibrinolysis in men with recent, uncomplicated myocardial infarction.

OBJECTIVES: This study investigated the effects of captopril therapy on endogenous fibrinolysis in men with recent, uncomplicated myocardial infarction. BACKGROUND: Angiotensin-converting enzyme inhibitors reduce the incidence of acute coronary syndromes in patients with mild left ventricular dysfunction after myocardial infarction. Abnormal endogenous fibrinolysis, reflected in increased levels of endogenous tissue-type plasminogen activator (t-PA) antigen and plasminogen activator inhibitor type 1 activity, is associated with an increased risk of myocardial infarction in patients with ischemic heart disease. METHODS: In a randomized, double-blind crossover study beginning 8 weeks after uncomplicated myocardial infarction, patients received 4 weeks of placebo and 4 weeks of captopril (75 mg daily) therapy. At the end of each treatment period, we measured t-PA antigen and plasminogen activator inhibitor type 1 antigen and activity. RESULTS: Median values in the 15 patients after placebo and in 12 normal men matched for age and body mass index were, respectively, t-PA antigen 16.0 versus 9.5 ng/ml (p = 0.001), plasminogen activator inhibitor type 1 antigen 17.3 versus 8.6 ng/ml (p = 0.29) and plasminogen activator inhibitor type 1 activity 13.2 versus 6.3 AU/ml (p = 0.04). After 4 weeks of treatment with captopril in the 15 patients, the estimated (95% confidence interval) median reduction in t-PA antigen was 7.3 ng/ml (-4.6 to -10.3 ng/ml, p = 0.001), in plasminogen activator inhibitor type 1 antigen 3.1 ng/ml (+1.5 to -8.4 ng/ml, p = 0.17) and in plasminogen activator inhibitor type 1 activity -2.2 AU/ml (-1.0 to -4.3 AU/ml, p = 0.02). CONCLUSIONS: Treatment with captopril after uncomplicated myocardial infarction is associated with a significant decrease in elevated levels of t-PA antigen and plasminogen activator inhibitor type 1 activity. This may help to explain the reduction in risk of coronary thrombosis associated with the use of angiotensin-converting enzyme inhibitors.

Captopril↗
PubMed1994

Frequent reinfection and reactivation of hepatitis C virus genotypes in multitransfused hemophiliacs.

The frequency and dynamics of infection with different genotypes of hepatitis C virus were investigated in a cohort of hemophiliacs repeatedly exposed to non-virus-inactivated clotting factor. Among 63 infected hemophiliacs, genotype 1 (n = 38, subtypes 1a [27] and 1b [11]) was predominant; genotypes 2a (n = 1), 2b (n = 3), 3a (n = 20), and 5a (n = 1) accounted for the remainder. This distribution was similar to that found in Scottish blood donors from whom the infected blood products were manufactured. Hemophiliacs with severe disease were more likely to be polymerase chain reaction-positive than those with moderate or mild disease. Over 10 years, changes in the circulating major genotype and serotype were observed in 9 of 29 hemophiliacs and from one subtype to another in 3, although there was no clear trend toward replacement with any particular variant. Replacement occurred after the introduction of inactivated clotting factor in 4 subjects, implicating reactivation rather than reinfection. Those coinfected with human immunodeficiency virus were more likely to show a change in genotype.

Blood Donors↗
PubMed1994

Raised plasma endothelin in unstable angina and non-Q wave myocardial infarction: relation to cardiovascular outcome.

BACKGROUND: Among patients with independent evidence of coronary disease and recent onset unstable angina or non-Q wave myocardial infarction the incidence of subsequent cardiovascular events is high. Markers predictive of adverse cardiac outcome in unstable angina and non-Q wave myocardial infarction need to be defined more accurately. Endothelin-1 is a potent endothelium derived vasoconstrictor peptide that may play a part in the pathophysiology of acute myocardial ischaemia. AIM AND STUDY DESIGN: In a study that specifically identified high risk patients a group of 16 consecutive patients with either unstable angina at rest or non-Q wave myocardial infarction were prospectively investigated to establish whether these conditions are associated with high plasma immunoreactive endothelin and whether endothelin concentration at presentation is related to cardiovascular events within the next 12 weeks. Controls consisted of a group of 40 healthy subjects. RESULTS: Patients had significantly higher mean (SD) plasma endothelin at presentation than did healthy controls (7.4 (1.1) v 5.0 (1.2) pg/ml, P < 0.0001). At nine weeks plasma endothelin was still significantly higher in those patients who had subsequent cardiovascular events, (n = 9, acute myocardial infarction or refractory angina with electrocardiographic changes and revascularisation procedures, 8.5 (2.6) pg/ml, P < 0.005 v controls) whereas its concentration returned to normal in those patients who had a favourable outcome (n = 7, 5.9 (0.7) pg/ml). Compared with those patients who had an uneventful course, patients with subsequent events had significantly higher plasma endothelin, both at presentation and at nine weeks (P < 0.05 on both occasions). IMPLICATIONS: Endothelin may contribute to the pathophysiology of acute coronary syndromes and may relate to subsequent cardiovascular outcome.

Adolescent↗
PubMed1994

Study of endothelial t-PA and vWf in normal subjects and in von Willebrand's disease.

Some well-described similarities exist between tissue plasminogen activator (t-PA) and von Willebrand factor (vWf) which may suggest a link in either the synthesis or release of both proteins from endothelial cells. To investigate this relationship further immunocytochemical localization of t-PA and vWf was performed in normal tissues and in skin obtained from patients with type I and type III von Willebrand's disease (vWd). Components of the fibrinolytic system were measured at baseline and after venous occlusion in healthy controls and patients with vWd. Patients with severe vWd received intravenous vWf concentrate, followed by desmopressin (DDAVP), to study the plasma response of vWf and t-PA. By immunocytochemical staining, t-PA was demonstrated in endothelial cells of normal skin, kidney and liver and also in the skin of patients with type I and type III vWd. vWf was localized in endothelial cells of all tissues except the specimens from an individual with severe vWd. Basal plasma levels of fibrinolytic components were normal in patients with vWd. Venous occlusion resulted in a rise of fibrinolytic activity in controls and patients with type I, but not type III, vWd. No rise in plasma t-PA was observed following DDAVP in severe vWd, even though near-normalization of plasma vWf levels had been obtained by prior infusion of vWf concentrate. It is concluded that the synthesis of t-PA and vWf is probably regulated by independent processes. Constitutive and regulated release of both proteins occur through different mechanisms and the basal secretion of t-PA is intact in severe vWd.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Use of porcine factor VIII in the treatment of patients with acquired hemophilia.

Data have been collected from 47 centers in Europe and North America on the treatment with porcine factor VIII concentrate of 74 acute bleeding episodes in 65 patients with acquired hemophilia. The median initial anti-human factor VIII auto-antibody inhibitor level was 38 Bethesda unit (BU)/mL (range 1.2 to 1,024) whereas that against porcine was 1 BU/mL (range 0 to 15). The mean initial dose of porcine factor VIII infused was 84 IU/kg, which increased the plasma factor VIII:C activity by 0.85 IU/mL. Therapy was continued for a mean of 8.5 days during which time the average number of infusions was 11. Objective clinical responses were rated as good or excellent in 78% of recipients. Side effects were uncommon; only one patient experienced a severe anaphylactic reaction necessitating the discontinuation of porcine FVIII therapy. After therapy, no increase in the median level of anti-human FVIII or anti-porcine antibody was noted in the group as a whole, although 13 patients showed individual increases in either anti-human or anti-porcine antibody levels or both of more than 10 BU/mL. Of the 7 patients who subsequently rebled, 5 were successfully re-treated and 2 did not respond to further porcine factor VIII treatment. Porcine factor VIII is safe and clinically effective treatment for bleeding episodes associated with acquired hemophilia and should be considered as first-line therapy for patients whose acquired anti-factor VIII:C antibody cross-reacts with porcine factor VIII:C at low levels.

Adolescent↗