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Biomedical subjects

M M Bern

Publications and source records attributed to M M Bern.

8 recordsLinked to original sources

Considerations for using lower doses of warfarin.

Warfarin is a very effective anticoagulant when used in the standard dose; however, the definition of standard dose has become ambiguous as the importance of the thromboplastin used in the measure of the prothrombin times has been demonstrated. Full or "standard" anticoagulation with warfarin imposes a hemorrhagic risk that can be avoided using lower doses. The premise has now been established that less than standard doses are efficacious. What is yet to be determined, however, is how low the dose of warfarin may be while maintaining efficacy and in which clinical settings. These conclusions must be established cautiously in clinical settings before being advocated generally. More complete discussions of this topic as well as safer means of using warfarin in general are available.

Atrial Fibrillation

Intraaterial hepatic infusion and intravenous adriamycin for treatment of hepatocellular carcinoma: a clinical and pharmacology report.

Four patients received intraarterial (ia) hepatic infusion and 10 received intravenous (iv) adriamycin for hepatocellular carcinoma. Four of each group are evaluable. The remaining 6 patients died within 14 days of intravenous therapy and are, therefore, considered nonevaluable. Patients received 2 to 9 courses of adriamycin every 3 weeks. One half of each group of evaluable patients had partial responses (pr). The group had pr for 22.5 weeks (range 8 to 37). The iv group had pr 27.2 weeks (range: 16 to 38.5). Mean survival was 21 weeks for nonresponders, and 43 weeks for responders. Intraarterial infusion did not protect patients from adriamycin toxicity. Cardiac and liver toxicity were not seen, but marrow and gastrointestinal toxicity developed at 1.2 X 10(-7)M adriamycin serum level. Adriamycin disappearance curves after ia and iv therapy were similar for similar bilirubin levels, and prolonged with hyperbilirubinemia. Ascites fluid did not accumulate detectable adriamycin. Pharmacokinetics are described in this report.

Adolescent

Selective platelet immune retention.

Inbred rats were immunized with Freund's Adjuvant containing proteins of Mycogacterium tuberculosis, Mycobacterium butyrium, or dinitrochlorobenzene (DNCB). Native arterial blood was then passed over glass beads coated with those antigens. The platelet retention on the glass beads was measured. Rats immunized with Complete Freund's Adjuvant developed accelerated platelet retention on beads coated with protein derivatives of tuberculosis (PPD) after just 18 seconds of blood flow. Rats immunized twice maintained selective retention longer than those immunized once. The test animals developed no cutaneous hypersensitivity nor precipitin lines on Ouchterlong gels against PPD. Rats sensitized to DNCB had accelerated platelet retention on DNCB-coated beads. Results were temperature and complement dependent, and antigen-specific. Heparin caused a dose-dependent inhibition of the accelerated retention. PPD potentiated the ADP-induced aggregation of plateletrich plasma (PRP) from immunized rats. These experiments suggest that platelets react selectively to antigens in the intravascular spaces in immune reactions.

Animals

Variable response of activated partial thromboplastin time to heparin therapy during hemodialysis.

The consistency of the anticoagulant effect of intravenously administered heparin was studied. The activated partial thromboplastin time (APTT) was measured for six patients hourly during three consecutive hemodialysis sessions each. Cephaloplastin was the plasma-activating agent. The time required to form a clot was measured by a light-sensitive electronic timer and confirmed within +/- 5% by the tilt tube method. Results are reported in second relative to units of heparin given to patients per kilogram body weight. The range of APTT's measured 55 minutes after each heparin dose greatly exceeded the range of technical variability of the assay method. The probably mechanisms and consequences for this variability after a constant heparin dose are discussed. The anticoagulation effect of heparin during hemodialysis in an otherwise stable clinical situation is not constant. The risks of having too much or too little anticoagulation are not eliminated by having determined a therapeutic heparin dose during one dialysis rung.

Blood Coagulation Tests