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Biomedical subjects

J F Davidson

Publications and source records attributed to J F Davidson.

At least 37 records · Page 2Linked to original sources
PubMed1992

Cerebral cardiovascular and respiratory variables after an experimental brain missile wound.

Brain missile wounding (BMW) affects brainstem and medullary cadiorespiratory functions leading to immediate systemic hypertension, bradycardia, and apnea. Secondary complications may also occur because of subsequent changes in systemic and intracranial physiological variables. To delineate the immediate and secondary effects of BMW, we monitored changes in several cerebral and cardiorespiratory parameters in pentobarbital-anesthetized spontaneously breathing cats before wounding and up to 90 min afterward. Total and regional cerebral blood flow (rCBF) and cardiac output (CO) were measured (microsphere technique) and arterial blood was sampled for pH, PO2 and PCO2 once before BMW and one to four times afterward. Mean arterial blood pressure (MABP), intracranial pressure (ICP), cerebral perfusion pressure (CPP = MABP - ICP), electrocardiogram (ECG), heart rate (HR), and electroencephalogram (EEG) were continuously recorded. Respiratory frequency (f), tidal volume (Vt), and ventilation (V) were recorded during each flow measurement and periodically throughout the experiment. Four unwounded cats served as controls and 15 cats were wounded at 1.4 J fronto-occipitally through an intact cranium. Unwounded cats showed no significant changes in any physiological variable measured during a 100 min experimentation period. Four wounded cats survived a 90 min post-BMW period and had only a transient brainstem effect including a 50% increase in MABP concurrently with 50% reductions in the f and HR. Nonsurvivors (11 of 15) lived from 1 to 41 min after wounding. These cats initially demonstrated similar changes in MABP, f, and HR to survivors, but these variables remained unstable, possibly indicating a persisting brainstem damage. Apnea accounted for death in 10 of 11 nonsurvivors. Although the primary brainstem effect might have existed in all nonsurvivors, it appears that only one cat died from reduced respiration alone. Others had one or several postwounding secondary complications: abruptly increased ICP producing a negative CPP, extreme reductions in CO or CBF and ventilation. Cardiac arrest occurred once. Thus, post-BMW mortality cannot be consistently ascribed to the impairment of a single physiological variable.

Analysis of Variance↗
PubMed1990

Correction of facial deformities in patients with mild bleeding disorders: a report of three cases.

A bleeding diathesis need not be a contra-indication to elective surgical correction of facial deformities. Preoperative haemostatic assessment and management of haemostasis during and after surgery is described. Two cases of mild von Willebrand's disease and one case of factor XI deficiency who successfully underwent orthognathic surgery for the correction of facial deformities are reported.

Adolescent↗
PubMed1989

Quantification of extracorporeal platelet deposition in cardiopulmonary bypass: effects of ZK 36374, a prostacyclin analogue.

The degree of extracorporeal platelet sequestration in 32 patients undergoing cardiopulmonary bypass has been assessed using 111In labelled platelets and both a shadow shield whole body monitor and a standard gamma camera. The effects of ZK 36374, a prostacyclin analogue, on deposition of platelets in the oxygenator and atrial line filter were also investigated. Total platelet deposition in the placebo group ranged from 2.2% to 31.7%, mean 13.9 +/- 7.8%; n = 15, and was significantly higher than the deposition in the treatment group, range 0.7% to 9.4%, mean 3.9 +/- 2.6%; n = 16, P less than 0.001. There was also a highly significant correlation between the gamma camera and whole body monitor measurements, r = 0.99, P less than 0.001, with no systematic difference between the techniques. This study demonstrates that accurate quantitative assessment of platelet deposition can be achieved with either the gamma camera or whole body monitor. In addition, significant reduction in platelet sequestration in the extracorporeal circuit can be achieved by using ZK 36374 during the bypass operation.

Adult↗
PubMed1987

Aluminium bone disease in patients receiving plasma exchange with contaminated albumin.

Aluminium balance studies were carried out on eight patients with various immunological disorders who were receiving plasma exchange with albumin solutions known to be contaminated with aluminium. Four patients with impaired renal function (creatinine clearance less than 50 ml/min) retained between 60% and 74% of the aluminium infused during a single plasma exchange. Transiliac bone biopsy specimens from three patients in this group had a high content of aluminium and showed histological evidence of current or previous bone disease related to aluminium. Two of these patients suffered intermittent bone pain. The main route of excretion of injected aluminium was in urine, only a small proportion of the total input being removed in the "plasma bag" during plasma exchange. The extent of aluminium retention and bone deposition was not reflected by the plasma aluminium concentration before or after plasma exchange. Treatment of five patients with intravenous desferrioxamine increased the plasma aluminium concentration and urinary output of aluminium in those with evidence of aluminium retention. These studies show that patients with poor renal function receiving treatment with albumin contaminated with aluminium retain the metal and deposit it in bone, where it may eventually cause aluminium bone disease. Plasma exchange should be used with caution in patients with renal impairment.

Adult↗
PubMed1987

Plasma fibrinolysis during and after normal childbirth.

A detailed sequential study of plasma fibrinolytic components in 42 healthy women during and after childbirth showed that striking changes occurred within minutes of placental separation. Significant increases in overall fibrinolytic activity were detected 15 min after delivery. During this period statistically significant increases in tissue plasminogen activator levels were noted but were overshadowed by a dramatic decrease in the level of plasminogen activator inhibitor (PAI). A 10-fold fall in PAI was noted by days 3-5 post-partum, suggesting that the placenta is the major source of PAI detectable at the end of pregnancy and during labour. Persisting slightly elevated levels of PAI were detected for the first few days post partum. This may be due to increased production of normal 'endothelial' PAI in response to the vascular trauma incurred by placental separation, and in response to uterine vascular changes immediately post-partum.

Antigens↗
PubMed1987

Prophylactic use of antithrombin III concentrate following surgery in congenital antithrombin III deficiency.

Antithrombin III is the major physiological inhibitor of thrombin, and congenital deficiency of antithrombin III is associated with increased risk of venous thrombosis either spontaneously or following trauma, surgery or pregnancy. The successful use of antithrombin III concentrate during and following surgery to prevent venous thrombosis is described in a previously asymptomatic man with familial antithrombin III deficiency.

Antithrombin III↗
PubMed1987

Control of oral anticoagulant treatment by chromogenic prothrombin assay.

Doses of oral anticoagulants in 50 patients on long term treatment were easily and satisfactorily monitored over six months by an automated chromogenic assay of prothrombin (CPA). It is suggested that chromogenic assay of one or more of the vitamin K dependent coagulation factors would provide a readily standardised alternative to those conventional tests which depend on human brain derived reagents, now regarded as a biohazard.

Administration, Oral↗
PubMed1987

Mesenteric venous thrombosis and antithrombin III deficiency.

Of the 123 patients with acute mesenteric infarction treated over the past 12 years, 16 (13%) had mesenteric venous thrombosis. Eight of the patients with mesenteric venous thrombosis survived the initial episode; two have since died. The remaining six patients were studied for evidence of haemostatic deficiencies or abnormalities. Antithrombin III deficiency, which is known to be associated with recurrent venous thrombosis, was found in three patients. It is recommended that all patients with mesenteric venous thrombosis should be screened for antithrombin III deficiency as treatment with coumarin anticoagulants may be indicated, providing effective prophylaxis against further thrombotic episodes.

Adult↗
PubMed1986

An international and interregional comparison of haemostatic variables in the study of ischaemic heart disease. Report of a working group.

Levels of haemostatic variables that may be involved in thrombogenesis have been compared in groups of men of similar mean age in communities at very low (Gambia), high (England and Czechoslovakia) or very high (Scotland and Finland) risk of ischaemic heart disease (IHD). There was a consistent gradient of higher factor VII levels with higher IHD risk and also suggestive gradients in the case of two other vitamin K dependent factors, factors II and X. Mean platelet counts were lower and mean fibrinolytic activity was greater in Gambian men than in European men. There was a suggestive though not entirely consistent association between mean fibrinogen levels and IHD risk in the groups from IHD-endemic countries. The results as a whole, and particularly those on factor VII, strengthen the case for the increasingly detailed epidemiological as well as laboratory investigation of the role of the haemostatic system in thrombogenesis and IHD.

Adult↗
PubMed1985

Effect of Ciprofibrate on platelet aggregation and fibrinolysis in patients with hypercholesterolaemia.

The fibrinolytic and platelet effects of Ciprofibrate, a new lipid lowering drug, were studied in 7 patients with hypercholesterolaemia over a 12 week period. A significant reduction in plasma fibrinogen was noted and a lesser increase in fibrinolytic activity. However, no change in platelet aggregation was noted. As expected Ciprofibrate produced a significant hypolipidaemic effect in these patients. We have described effects of Ciprofibrate which may have potential benefits in this high risk patient group.

Adult↗
PubMed1985

The effect of the synthetic steroid Org OD14 on fibrinolysis and blood lipids in postmenopausal women.

Two groups of postmenopausal women were compared. One group of 13 was given the synthetic steroid Org OD14 to suppress climacteric symptoms and one group of 14 was given placebo. After a 2 week baseline period the subjects received daily for 12 weeks, either 2.5 mg Org OD14 or placebo. There were no significant differences between the groups pre-treatment. Compared with the placebo group, during treatment, the Org OD14 group showed the following significant differences: higher haemoglobin, haematocrit, platelet count, plasminogen, fibrinolytic activity on fibrin plates and antithrombin III and lower fibrinogen. No significant differences between the groups were found in alpha 2 antiplasmin levels, total cholesterol, total triglycerides, bilirubin or transaminase levels but the Org OD14 group had significantly lower levels of HDL cholesterol. With the exception of the haemoglobin and haematocrit levels all of the differences had disappeared by 2 weeks post treatment.

Adult↗