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Biomedical subjects

S J Machin

Publications and source records attributed to S J Machin.

At least 181 records · Page 10Linked to original sources
PubMed1986

HTLV-III antibody and T-cell subset ratios in haemophiliacs and their spouses.

44% of 63 British patients with either haemophilia A or B were HTLV-III antibody positive (HTLV-VIII+). HTLV-III+ was more frequent in high factor VIII concentrate users and 75% of severely affected haemophilia A patients were HTLV-III+. All eight patients who were exposed to factor IX concentrate were HTLV-III-. 17 haemophilia A patients who received only British made factor VIII concentrate (average 12,000 units/year) were HTLV-III-. Two of 63 patients had evidence of a pre-AIDS type symptom complex and both were HTLV-III+. Information from a cohort of 21 Liverpool haemophiliacs suggests that HTLV-III was first introduced into this country in 1981. OKT4/T8 ratios were abnormal in 52% of 21 patients studied but this finding was not confined to either HTLV-III+ or HTLV-III- individuals. The spouses of 14 HTLV-III+ haemophiliacs were all HTLV-III-.

Adolescent↗
PubMed1986

Heat-treated NHS factor VIII concentrate in the United Kingdom--a preliminary study.

Three patients who have been given intermediate purity NHS heat-treated factor VIII concentrate have been followed prospectively for 7-10 months. None had previously received more than six donor units of blood products containing factor VIII. There were no clinical side effects from concentrate administration, haemostasis was satisfactory and no patient developed clinical or laboratory evidence of hepatitis or HTLV III/LAV infection. Heat treatment resulted in the loss of slightly more than 20% of factor VIII activity but in vivo recovery of factor VIII and half disappearance times were within the expected range.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Effects of N-methyl-thiotetrazole cephalosporin on haemostasis in patients with reduced serum vitamin K1 concentrations.

Two patients with low random serum vitamin K1 concentrations but with normal prothrombin times and normal biological assays of the vitamin K dependent coagulation proteins were treated with an N-methyl-thiotetrazole cephalosporin (cefotetan) postoperatively. Four to six days later both patients developed a prolonged prothrombin time and a noticeable and specific lowering of the clotting activities of factors II, VII, IX and X, though the serum vitamin K1 concentrations remained unchanged. Crossed immunoelectrophoresis of prothrombin showed the appearance of a second peak corresponding to descarboxyprothrombin (PIVKA II). These abnormalities corrected after vitamin K administration. These data are consistent with the hypothesis that cephalosporins with an N-methyl-thiotetrazole side chain inhibit the hepatic utilisation of vitamin K but that this only causes hypoprothrombinaemia when liver reserves of vitamin K are low.

Aged↗
PubMed1986

Laboratory investigation of platelet function: a review of methodology.

Over the past decade interest in and knowledge about the role of platelets in the haemostatic process and in various pathological conditions has continued to grow. The scope of laboratory methodology to investigate platelet function in clinical haemorrhagic and thrombotic disorders in the specialised haemostasis unit has also proportionally widened. After highlighting the physiological processes of the role of platelets in the haemostatic mechanism this brief review comments critically on the available routine techniques used to study platelet function in patients who present primarily with a bleeding tendency.

Adenine Nucleotides↗
PubMed1986

Platelet function studies during and after infusions of ZK 36374, a stable prostacyclin analogue, to healthy volunteers.

ZK 36374 (Iloprost), a stable prostacyclin analogue, was administered to 6 healthy volunteers for 2-hour periods, with dose rates increasing from 0.5 to 2 ng/kg/min within that time. At these doses, which did not give troublesome side effects clinically, there was significant inhibition of ex vivo platelet aggregation responses to ADP and collagen. There was some rebound platelet hyperaggregability in all subjects, occurring between 1 and 2 h after termination of the infusion; this was of minor degree and was not associated with any clinical problems.

Adenosine Diphosphate↗
PubMed1985

The effects of nicotine on PGI2 production by rat aortic endothelium.

The production of prostacyclin by rat aortic rings was measured following administration of nicotine by a single subcutaneous injection and after continuous subcutaneous infusion over 7 days. Single subcutaneous injections of nicotine at 1, 5, 10 or 20 mg/kg had no effect on prostacyclin production by rat aortic rings in comparison with controls. However, aortic rings obtained after 7 days continuous subcutaneous infusion of 0.54 g/ml of nicotine at the rate of 1 microliter per hour produced significantly less prostacyclin than control animals.

Animals↗
PubMed1985

The haemostatic effects of hydroxyethyl starch (HES) used as a volume expander.

Hydroxyethyl starch (HES 450.000/0.7; Hespan 6.0 g/100 ml) was compared with standard crystalloid solutions in postoperative volume replacement in 20 patients undergoing routine orthopaedic surgery. The HES group showed no clinical evidence of haemorrhage and no laboratory evidence of significant haemostatic defects as assessed by standard coagulation tests, platelet aggregation and fibrinogen concentrations. There was a slight shortening in the thrombin time and a smaller increase in post-operative FVIII RAg and FVIII RCof levels in the HES group. HES is a safe and effective volume expander for postoperative use.

Adolescent↗
PubMed1985

Platelet hyperaggregability occurring during prolonged continuous intravenous infusions of prostacyclin analogue ZK 36374.

We describe two patients suffering from vascular problems refractory to conventional treatment, who received prolonged continuous infusion of ZK 36374, a stable prostacyclin analogue. During the infusion, the patients' platelets became progressively refractory to the in vitro inhibitory action of exogenous ZK 36374. During the early stages of the infusions, platelet aggregability studied ex vivo was inhibited, but this effect too diminished progressively as the infusions continued. The platelets of one patient become spontaneously aggregable and hyperaggregable to standard agonists during the last 2 d of his 9 d infusion. This effect was not seen during an initial 10 d infusion in our second patient, who was concurrently receiving indomethacin, a reversible cyclo-oxygenase inhibitor. However, such hyperaggregability became evident in the platelets of this patient during a second, shorter continuous infusion after cessation of the indomethacin. The hyperaggregability was accompanied in each case by a significant rise in serum thromboxane B2 levels.

Cardiovascular Agents↗
PubMed1985

Measurement of platelet aggregation in diabetics using the new electronic platelet aggregometer.

Platelet function has been studied in diabetic subjects using a new electronic platelet aggregometer which enables platelet aggregation to be studied in whole blood. This may be a more physiological approach to the assessment of platelet behaviour as centrifugation is avoided and platelets are studied in the presence of other blood elements which may be important modulators of platelet function in vivo. Twenty insulin-dependent diabetic subjects were studied along with 20 age and sex-matched controls. Platelet aggregation to collagen (1 microgram/ml) and arachidonic acid (1 mM) was significantly increased in the diabetic group. In addition the sensitivity of diabetic platelets to the antiaggregatory effects of prostacyclin was significantly reduced. A significant inverse correlation was found between platelet sensitivity to prostacyclin and glycosylated haemoglobin concentration in the diabetic group. It is unlikely that the platelet abnormalities in this diabetic group are due to underlying vascular disease as none of the patients had evidence of diabetic complications. These findings may have important implications for the development of vascular disease in diabetics.

Adult↗
PubMed1984

The mesothelial cell as a non-thrombogenic surface.

A technique for harvesting mesothelial cells is described. This entails collagenase digestion of omentum after which the cells can be cultured. The technique has been developed using the rat, but has also been successfully applied to human tissue. Cultured rat mesothelial cells obtained in this way have been examined by scanning electron microscopy. Rat mesothelial cells grown on plastic film have been exposed to blood in an in vitro system using a Baumgartner chamber and have been demonstrated to support blood flow. No adhering platelets were observed on the mesothelial cell surface. Fibroblasts similarly exposed to blood as a control were washed off the plastic.

Animals↗