DENTAL EXTRACTION DURING DICUMAROL THERAPY

Extraction of 14 teeth in six patients taking dicumarol caused no unusual bleeding. Discontinuance of dicumarol prior to dental extraction should not necessarily be a routine procedure; in certain persons with a demonstrated strong tendency to recurrent thrombosis, dicumarol should be continued, based on the decision that the danger of clotting without the drug is greater than the danger of bleeding with the drug.     

Hemorrhage During Long-Term Anticoagulant Drug Therapy — Part III: The Relationship of Minor to Serious Bleeding

In a study of reports of 805 instances of spontaneous bleeding occurring among 2,189 patients receiving long-term anticoagulant drug therapy, 124 episodes were considered serious and 681 minor. There was no significant correlation of minor bleeding and serious bleeding.Minor bleeding unassociated with excessive reduction of coagulability or an underlying organic lesion could not be considered, according to this evidence, an indication for discontinuance of anticoagulant drug therapy.In apparently minor internal bleeding, however, hidden underlying organic lesions must be excluded. If gross hematuria occurs, renal lesions must be excluded.Rectal bleeding must not be considered minor until gastrointestinal lesions have been excluded.     

Hemorrhage During Long-Term Anticoagulant Drug Therapy—Part IV: Selection and Management of Patients

Most serious hemorrhages that occur during long-term anticoagulant drug therapy are due either to poor patient selection or to poor management of the patient, or both.In each patient being considered for treatment, the risk of bleeding must be evaluated and classified as high, moderate or low.The clinician must especially assess the risk of intracranial hemorrhage in hypertensive patients, and must screen all patients for potential sources of gastrointestinal bleeding. There is ample time for such investigations, since initiating long-term anticoagulant therapy is not an emergency procedure.The desired level of prothrombin activity must be adjusted to the risks determined for each individual patient. There is no single “therapeutic range” applicable to all patients with their varying hemorrhagenic risks.Proper management includes sufficient laboratory testing to maintain the desired prothrombin level, and continued vigilance to detect signs of early bleeding.Preventable hemorrhage cannot be cited as evidence against the value of anticoagulant drug therapy.     

Mysis in the Okanagan Lake food web: a time-series analysis of interaction strengths in an invaded plankton community

Mysis introductions to the lakes of western North America have shown they are important predators on zooplankton, especially daphnids, and intercept energy flows that would otherwise be available to pelagic fishes. However, understanding of the ecological roles of Mysis within invaded communities following their establishment remains weak. We analyzed zooplankton and phytoplankton data collected from Okanagan Lake, British Columbia, within a time-series framework to evaluate the strength of ecological interactions between Mysis and the other dominant plankton. Top-down effects of Mysis in the plankton community were only detected on cyclopoid copepods and cyanophytes. Mysis dynamics were mostly driven by bottom-up effects from diatoms and from small cladocerans whose dynamics were driven primarily by the abundance of edible phytoplankton. This result supports the growing appreciation of the importance of omnivory in mysids and was consistent between the two main basins of the lake. We also analyzed published stable C and N isotope data from the plankton of Okanagan Lake with an isotope mixing model to estimate the relative importance of various potential energy sources to Mysis. This analysis supported the time-series results suggesting the importance of diatoms and small zooplankton to Mysis. However, the isotopes also suggested important resource flows from Daphnia to Mysis, an interaction not detected in the time-series analysis. Taken together, these results suggest that Mysis is a strong interactor in the Okanagan Lake food web, relying in part on energy flow through Daphnia. However, subsidies from diatoms likely decouple seasonal Mysis population dynamics from the seasonal population dynamics of Daphnia.