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Biomedical subjects

C Prowse

Publications and source records attributed to C Prowse.

At least 37 records · Page 2Linked to original sources
PubMed1993

Prevalence and consistency of ALT elevation in plasmapheresis donors: implications for the assessment of blood product infectivity.

Alanine aminotransferase (ALT) levels were determined in 8,420 plasmapheresis donations obtained from 431 donors over a period of 18 months. Using sex-differentiated normal ranges 2.5% of donations but 23% of donors exhibited elevated ALT levels on at least 1 occasion. Amongst the donors with elevated ALT this was only seen on 1 occasion in one third, while a quarter had elevations in consecutive donations. No donors with consecutive elevations above 100 IU/l were detected. The results are discussed in terms of the guidelines currently recommended for assessing post-transfusion hepatitis infectivity of blood products, such as factor VIII. It is concluded that the current allowance for infection acquired from sources other than blood products under consideration may be over-generous, leading to a potential underestimate of the true rate of infection.

Adult↗
PubMed1992

The effects of type of factor VIII concentrate used in haemophilia on T-helper cell number and inhibitor incidence.

This review surveys the available published data on the impact of the type of factor VIII concentrate infused on T-helper lymphocyte count and factor VIII inhibitor induction in haemophiliacs. While concern has been expressed that certain products may have adverse effects on these parameters, only one trial published to date shows a significant benefit of a high purity product in reducing the rate of CD4 lymphocyte decline in HIV seropositive haemophiliacs. A number of other studies show no such significant benefit although the design of many of these might be criticized and few of them consider the potential impact of viral infection other than HIV, such as hepatitis C. More recent data on the incidence and prevalence of inhibitors in the haemophiliac population suggest that the reported high frequency of inhibitor formation for some products may lie within the expected normal range. This raises interest in why some products appear not to induce inhibitor formation, even in the group of patients at greater risk: multitransfused, severely deficient patients. The occasional reports of late onset high titre inhibitors in multitransfused haemophilia patients associated with the introduction of newer products are a matter of concern.

CD4 Antigens↗
PubMed1989

Human atrial natriuretic factor (ANF). Characterisation of a monoclonal antibody panel and its use in radioimmunoassay.

The production of nine monoclonal antibodies to human atrial natriuretic factor (ANF 1-28) is described. All possible combinations of two antibodies failed to reveal any which could simultaneously bind ANF. Studies with ANF analogues and the antibodies having the three highest affinity values (KD = 5, 25 and 21 pM) indicated that the antibodies are directed to the central portion of the antigen molecule. The highest affinity antibody was able to replace polyclonal antisera in the radioimmunoassay of ANF in extracts of plasma.

Antibodies, Monoclonal↗
PubMed1989

The molecular manipulation of milk composition.

The introduction of cloned genes into the mouse germ line is now routine. Although more difficult technically, gene transfer has been accomplished in farm animals and offers the potential for genetic improvement. In this regard, we have been investigating the use of transgenic animals as production vehicles for high value proteins in milk. We have shown that DNA sequences derived from the gene encoding sheep beta-lactoglobulin mediate efficient and specific expression in the mammary gland. A fusion gene comprising beta-lactoglobulin sequences and those encoding antihemophilic human factor IX has been constructed. This construct has been introduced into sheep; it is expressed in the mammary gland, and the corresponding protein is secreted into milk.

Animal Husbandry↗
PubMed1988

Studies on the procurement of blood coagulation factor VIII. In vivo studies on blood components prepared in half-strength citrate anticoagulant.

To determine the viability of blood cells collected in half-strength (0.5 CPD.A2) and full-strength citrate anticoagulants, paired crossover autologous survival studies were performed in normal volunteers using 51Cr-labelled red cells after 35 days storage and 111In-labelled platelets after 5 days storage. For both studies, viability was better maintained in 0.5 CPD.A2 anticoagulant. This was significant for red cells (24-hour survival: 80 +/- 6 vs. 52 +/- 21%) but not for platelets by either linear or multiple-hit models (recovery 51 +/- 13 vs. 38 +/- 14%, survival 5.1 +/- 1.4 vs. 3.7 +/- 1.5 days). The poor viability of red cells after storage in full-strength anticoagulant was associated with low cellular adenosine triphosphate levels and was confirmed in follow-up studies.

Adenine↗
PubMed1988

Studies on the procurement of blood coagulation factor VIII. In vitro studies on blood components prepared in half-strength citrate anticoagulant 18 hours after phlebotomy.

Our previous studies have shown that the use of half-strength citrate anticoagulant improves plasma factor VIII stability while maintaining the viability of red cells and platelets. This study extends these observations to show that the stability of factor VIII is maintained in blood stored at room temperature or 4 degrees C overnight and that in vitro tests indicate comparable quality of red cells and platelets prepared from half-strength citrate donations processed immediately or after overnight storage at room temperature. The exception to this was a more rapid loss of red cell 2,3-diphosphoglycerate, as has previously been observed for full-strength citrate donations.

Blood Platelets↗
PubMed1987

Studies on the procurement of blood coagulation factor VIII in vitro studies on blood components prepared in half-strength citrate anticoagulant.

The effect of replacing a standard citrate anticoagulant with one containing half the amount of citrate on the in vitro properties of components prepared from blood donations was investigated. This resulted in a significant improvement in factor VIII stability such that there was little loss during overnight storage, and this was reflected in the factor VIII yield in cryoprecipitate. The quality of cellular components in red cell units stored up to 35 days or platelet concentrates stored up to 7 days was not adversely affected. Although initial levels were similar to those in standard anticoagulant, the extent of fibrinopeptide A generation and complement C3 breakdown in red cell units stored for 35 days in half-strength citrate was somewhat increased.

Anticoagulants↗
PubMed1986

Room temperature, microtray chromogenic assay of factor VIII:C.

Commercial reagents of non-human origin were used to provide a room temperature, microtray chromogenic assay for factor VIII. The assay allows determination of factor VIII in the range 15-150% of normal plasma levels with a coefficient of variation of 3-4%. Haemophilic plasmas and factor VIII concentrates may also be assayed by varying the pre-dilution step. A good correlation was demonstrated with results obtained using an established one-stage clotting assay (r = 0.9985).

Factor VIII↗
PubMed1985

A diffusable factor in Scottish coagulation factor concentrates can inhibit lymphocyte transformation in vitro.

Coagulation factor VIII and IX concentrates produced in Scotland inhibited human lymphocyte transformation induced by lectins or the recall antigen, purified protein derivative of tuberculin (PPD). Although concanavalin A could bind factor VIII directly and PHA could bind factor IX directly, most of the inhibition was not due to direct clotting factor - lectin interaction nor to simple toxicity. Most of the inhibitory activity from both clotting factors could be removed by dialysis. A similar degree of inhibition was observed when the buffers used to prepare the concentrates were substituted for the concentrates themselves, and a comparable concentration of sodium citrate was also found to be inhibitory. Coagulation factor VIII partially purified by gel filtration was not found to have an appreciable effect on lymphocyte transformation in vitro.

Cells, Cultured↗
PubMed1985

Studies on the procurement of blood coagulation factor VIII: effects of plasma freezing rate and storage conditions on cryoprecipitate quality.

Plasma was frozen and stored in different ways before processing to cryoprecipitate by a standard thawing technique. Freezing rate was found to be important with slow freezing having a deleterious effect on cryoprecipitate quality. Storage of frozen plasma at constant temperatures for periods up to six months had no effect on the quality of cryoprecipitate, with no difference being found for plasma stored at -20 degrees C or -40 degrees C. Subjecting frozen plasma to deliberate temperature fluctuations resulted in a considerable increase in the amount of fibrinogen recovered in cryoprecipitate, with the factor VIII yield being relatively unaffected.

Blood Preservation↗
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↗
PubMed1982

Prevention of the platelet alpha-granule release reaction by membrane-active drugs.

A range of membrane-active drugs were tested for their ability to prevent beta-thromboglobulin and platelet factor 4 release from freshly collected blood platelets. While all the drugs tested could inhibit collagen-induced platelet aggregation, only a few, notably procaine and the anti-malarial drugs chloroquine, hydroxychloroquine, camoquine and quinacrine (mepacrine), effectively prevented the alpha-granule release reaction.

Alprostadil↗