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Biomedical subjects

B F Jacobson

Publications and source records attributed to B F Jacobson.

8 recordsLinked to original sources
PubMed2006

Thrombo-embolic and bleeding complications in patients with mechanical valve replacements--a prospective observational study.

BACKGROUND AND OBJECTIVES: Long-term anticoagulation therapy is essential to prevent thrombo-embolic events in patients with mechanical valve replacements. In order to offer indigent patients mechanical heart valve replacement surgery, dedicated anticoagulation clinics are necessary for follow-up. This study assessed the safety and efficacy of lifelong oral anticoagulation therapy in Johannesburg General Hospital mechanical heart valve replacement recipients. The incidence of bleeding and thrombo-embolic complications was documented in three groups of patients with mechanical valve replacements. The groups included patients with aortic valve replacements (AVRs), mitral valve replacements (MVRs) and double (aortic and mitral) valve replacements (DVRs). MATERIALS AND METHODS: A prospective observational study was conducted over a 4-month period. Data on 306 patients attending the Johannesburg General Hospital anticoagulation clinic between 2000 and 2005 were analysed. Of the total patients selected, 205 were assigned to the mechanical valve replacement group (which included 63 patients with AVRs, 93 with MVRs and 49 with DVRs); a control group of 101 nonmechanical valve replacement patients were also included. At each visit the level of anticoagulation was assessed from the international normalised ratio (INR) values, and the presence of bleeding and/or thrombo-embolic complications was documented. RESULTS: There were a total of 51 bleeding and thrombo-embolic complications in the study population. Patients with DVRs had a higher proportion of combined complications (30.61%) than patients with single valve replacements (14.29% in the AVR group and 18.05% in the MVR group) and patients in the control group (12.87%). There were 38 bleeding complications, 30 minor and 8 major. Twelve thrombo-embolic events were documented. Individually, there was no significant difference in thrombo-embolic and bleeding complications between the subgroups. Eighty-two per cent of patients in the mechanical valve replacement group were within the therapeutic range for anticoagulant control (INR 2.5-3.5) v. 54% in the control group (INR 2.0-3.0). Anticoagulant control was of a high quality and was not a contributing factor to the incidence of bleeding and/ or thrombo-embolic complications. CONCLUSION: The finding of a low incidence of bleeding and thrombo-embolic complications in patients with mechanical valve replacements supports the continued placement of mechanical valves in our setting and use of oral anticoagulation therapy at an INR of 2.5-3.5. However the increased risk of both bleeding and thrombo-embolic complications in the DVR group is cause for great concern and warrants further investigation.

Administration, Oral↗
PubMed2005

Erythrocyte sedimentation rate as a marker of inflammation and ongoing coagulation in stroke and transient ischaemic attack.

OBJECTIVE: Systemic infection and inflammation have been implicated in the aetiology of thrombotic cerebral events, particularly in younger patients. We decided to determine whether those patients with raised D-dimer levels, indicating continuing thrombosis and fibrinolysis, had evidence of concurrent infection or inflammation as manifested by a raised erythrocyte sedimentation rate (ESR) measured after an ischaemic stroke/transient ischaemic attack (TIA). METHODS: One hundred and forty-eight patients who had suffered either single or recurrent cerebrovascular episodes were analysed. The patients were referred to the thrombosis and haemostasis unit at Johannesburg Hospital for evaluation of their thrombotic profiles, including D-dimer levels. Concurrent infection was assessed by measurement of white cell count (WCC) and ESR. The variable time interval between the date of the most recent cerebrovascular event and the date of venesection was determined. A history was taken, a physical and neurological examination was performed, and a cardiology assessment and neuroimaging studies were done. RESULTS: Raised D-dimer levels correlated significantly with ESR levels (p = 0.0094) in all patients. This was particularly evident when comparing the 70 younger patients (aged less than 45 years) with the 78 older patients (> 45 years) with raised D-dimers (p = 0.0070). When analysing other markers of inflammation/infection in association with raised D-dimer levels and ESR, mean fibrinogen levels were significantly raised at 6.56 g/l (p = 0.0122). An elevated WCC, as a categorical variable, was significantly associated with an elevated ESR (p = 0.0092). CONCLUSION: There is a significant correlation between elevated D-dimer levels (indicating abnormalities of coagulation and fibrinolysis) and markers of inflammatory and/or infective processes. This is particularly evident in black patients below the age of 45 years. These patients are believed to be at decreased risk for generalised atheromatous disease compared with older white patients. The ramifications of these findings are potentially important with regard to thrombotic cerebrovascular disease aetiology, investigation, management and prevention.

Adult↗
PubMed2004

In vitro effects of thawing fresh-frozen plasma at various temperatures.

Thawing fresh-frozen plasma (FFP) in South Africa is uncontrolled because the plasma is issued frozen from the blood bank and thawing techniques and temperatures are at the discretion of the clinician. Following anecdotal reports of disseminated intravascular coagulation (DIC) developing in patients who received FFP thawed in an uncontrolled manner, the effects of various thawing temperatures on coagulation parameters were studied. Fifteen adult units of FFP were each divided into 4 satellite units by the South African Blood Transfusion Service before freezing at -25 degrees C. These bags were then defrosted in a waterbath at 22 degrees C, 37 degrees C, 45 degrees C and 60 degrees C, respectively, and removed as soon as they had thawed. Samples were collected for measurement of International Normalized Ratio (INR), prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen, and D-dimers. These tests were done according to standard operating procedures. FFP samples were also used in place of agonist in platelet aggregation studies to assess whether the FFP could induce platelet aggregation. Results were analyzed with the percentage similarity model. Using this method the percentage similarity (%sim) of each bag thawed at each temperature with the same donor's bag thawed at 37 degrees C was calculated. The mean, standard deviation, and percentage coefficient of variation of the percentage similarities were then derived. Data sets were also compared using the Wilcoxon test. The fibrinogen values remained stable at 22-45 degrees C (%sim = 97-99%) while there was a significant decrease in fibrinogen levels at 60 degrees C compared with 37 degrees C (p<0.001, %sim = 75%). INR and PTT values were highest in the bags thawed at 60 degrees C (%sim = 114% and 110%, respectively) with the difference between the INR levels at 60 degrees C compared with 37 degrees C showing statistical significance (p<0.05). D-dimers were high at all temperatures tested with widely ranging results at each temperature. The FFP did not induce platelet aggregation at any of the thawing temperatures. In summary, INR and PTT values increase at a thawing temperature of 60 degrees C compared with 37 degrees C. D-dimers are elevated in thawed FFP. Fibrinogen levels are markedly decreased in FFP thawed at 60 degrees C compared with that thawed at 37 degrees C. FFP should be thawed at 37 degrees C in a strictly controlled environment.

Adult↗
PubMed1995

Fluoxetine and hemostatic function: a pilot study.

BACKGROUND: Isolated case reports have appeared implicating fluoxetine as a cause of impaired hemostatic function. The authors attempted to investigate this phenomenon. METHOD: The hemostatic function of 10 patients with DSM-III-R major depression was investigated before and after a trial of treatment with fluoxetine. The tests included international normalized ratio, partial thromboplastin time, factors II, V, VII, VIII:C, IX, X, XI, XII, fibrinogen, thrombin time, bleeding time, euglobulin lysis time, protein kinase C, antithrombin, platelet counts, D dimer, lupus inhibitor, and platelet sensitivity studies to the following agonists: adenosine diphosphate, epinephrine, collagen, and arachidonic acid. Hemostatic data on a patient with a drug-related bleeding episode are not available. RESULTS: No significant difference was found in any of the parameters tested. CONCLUSION: This study failed to demonstrate any compromised hemostatic function associated with fluoxetine therapy. However, the possibility of a type II statistical error exists. It is possible that bleeding events may occur as an idiosyncratic reaction to fluoxetine treatment.

Adult↗
PubMed1980

Role-model concepts before and after the formal professional socialization period.

Physical therapy students in baccalaureate-degree programs used a forced-choice Q sort of 49 characteristics of physical therapists to describe their concepts of a physical therapy role model at the beginning and again at the end of basic professional training. In ranking the items with the 10 highest mean values (most descriptive) for each sorting, two items represented technical and eight items represented personal characteristics. The same nine items remained highest for both Q sorts. In comparing the high-ranking items to those rankings of sortings performed by recent graduates and by physical therapists, six items were the same. The majority of the correlations between the students' pretraining and posttraining Q-sort scores were significant, with moderate degrees of correlation. The investigator concluded that physical therapy students' role-model concepts were fairly similar before and after professional training. Personal, rather than technical, characteristics best described the physical therapy role model.

Clinical Competence↗
PubMed1978

Characteristics of physical therapy role models.

This study examined the personal and technical characteristics used in an investigation of role modeling in physical therapy. Recently graduated physical therapists performed a forced-choice Q sort composed of 49 physical therapist characteristics to describe 1) themselves, 2) their model academic instructor, and 3) their model clinical instructor. A significant difference between the frequency of personal and technical characteristics placed in the Most Descriptive section resulted for the self sort. The 10 characteristics ranked by highest mean values were all personal for self sorts, the majority were personal for the clinical model and combined sorts, and were equally divided between personal and technical for the academic model sorts.

Adult↗
PubMedDate not supplied

Mechanism of thrombosis caused by sclerotherapy of esophageal varices using sodium tetradecyl sulphate.

The mechanism of thrombosis following intravariceal injection of sodium tetradecyl sulphate (S.T.D.) was investigated with respect to effects on the vascular endothelium, the coagulation cascade, and platelet function. Using an umbilical cord model designed to simulate blood flow over the endothelium, it was found that S.T.D. is a potent toxin for endothelial cells in that brief exposure to even low concentrations of the agent were effective in stripping endothelium over a considerable distance, exposing highly thrombogenic endothelium in the process. Effects on coagulation and platelet function were found to be dependent on concentration. Diluted S.T.D. induced a hypercoagulable state, possibly in consequence of a selective inhibition of the physiological anticoagulant, protein C, and promoted platelet aggregation. Higher concentrations inactivated the coagulation cascade and lysed platelets completely. These results suggest that intravariceal infusion of S.T.D. at considerable dilution may be at least as effective in inducing thrombosis as standard dosage, and possibly more so.

Blood Coagulation↗