Increased antibiotic resistance of E. coli exposed to static magnetic fields.

The present study demonstrates that exposure of bacteria to medium strength static magnetic fields can significantly alter antibiotic sensitivity. Cultures of Escherichia coli were exposed to fields produced by permanent magnets. Samples of bacterial cultures continuously growing in the presence and in the absence of static magnetic fields were left untreated or were treated with an antibiotic and measured at 45 min intervals for cell growth and survival. It was found that exposure of E. coli to the static fields significantly increased antibiotic resistance. Bioelectromagnetics 22:129-137, 2001. Published 2001 Wiley-Liss, Inc.

Histological findings after brown recluse spider envenomation.

Histologic specimens from 41 rabbits were studied for changes resulting from the manual injection of brown recluse spider venom. Major findings included a mixed inflammatory cell infiltrate, coagulative tissue necrosis, and vasculitis. All specimens demonstrated a well-delineated zone of eosinophilic staining recognizable as "mummified" coagulative necrosis of the epidermis and dermis. A dense band of neutrophils bordered the zone of necrosis. Immediately adjacent to the neutrophilic band, small vessel vasculitis was a universal finding. Degranulated eosinophils and neutrophils and macrophages filled with eosinophilic granules were common. Inflammatory foci were often centered on groups of lipocytes within the dermis. Large vessel vasculitis resembling that seen in polyarteritis nodosa was present deep to 7 of the 40 eschars. Large vessel vasculitis may contribute to the large zones of necrosis seen after some brown recluse spider bites. Eosinophils may play a role in tissue damage after envenomation.

Drawing specimens for coagulation testing: is a second tube necessary?

Three recent studies discussed the possibility that the National Committee for Clinical Laboratory Standards (NCCLS) recommendations that the coagulation specimen should be the second or third tube collected are unnecessary. However, only one reagent/instrument was used in each study. Our protocol differed from the previous studies because we performed the assays on three different reagent/instrument systems on the same samples. Our study used photo-optic, mechanical, and nephelometric systems of clot detection. After obtaining informed consent, we obtained two blue-stoppered tubes of blood from 95 subjects: 15 normal patients and 80 patients currently on coumadin therapy. No discard tube was drawn for coagulation testing. A prothrombin time with an international normalized ratio and an activated partial thromboplastin time, were performed on each tube. Laboratory One used a MLA 1600C (Hemoliance) with Thromboplastin DS (Pacific-Hemostasis, ISI of 1.11) and APTT-LS (Pacific-Hemostasis). Laboratory Two used an STA (Diagnostica-Stago) with Neoplastine CI+ (Diagnostica-Stago, ISI of 1.14) and PTT-LT (Diagnostica-Stago). Laboratory Three used an ACL 300 with Plastinex (Biodata, ISI of 1.67) and Actin FSL (Dade Behring). No clinical or statistically significant differences were seen between the first or second tubes on any of the three reagent/instrument combinations in the PT in seconds, international normalized ratio reporting, or APTT results. Our results indicate that the NCCLS guidelines for obtaining a second tube when performing coagulation testing should be considered for elimination when new revisions are published.

Oral anticoagulant therapy and international normalized ratios in swine.

While monitoring coagulation testing in Yucatan miniature swine being given oral anticoagulants, we noticed instances of high international normalized ratios (INR) without clinical complications in our animal model. All pigs (n = 17) weighed approximately 35.2 kg and were dosed daily with 2 to 3 mg of coumadin. Plasma samples were obtained and assayed for prothrombin time (PT), calculated INR, and activated partial thromboplastin time (APTT) at baseline, and after 7 and 14 days of coumadin therapy. Results of initial testing indicated high INR values after anticoagulation and short APTT values at baseline, which led us to consider the activity of vitamin K-dependent coagulation factors in the pig. This information was not available in literature concerning this strain of swine, and was surprising given that pigs are frequently used cardiac research models. Using the same plasma samples, we repeated the PT, INR, and APTT determinations using different reagents and a different analyzer. We also determined activities of coagulation factors II, VII, IX, and X. Large PT and INR differences were seen between the two instrument/reagent combinations, possibly due to the differences in the thromboplastins used and differences in the photo-optic versus manual clot-detection method of the instruments. Vitamin K-dependent factors in all pigs responded to coumadin by decreasing to < 30.0% activity, except for factor IX. The high INR values were not as pronounced when the second instrument/reagent combination was used, and the results seemed more in line with the animals' clinical condition. With this instrument/reagent combination, the pig can be considered a good model for research requiring oral anticoagulant medication.

Peripheral blood lymphocyte apoptosis: a clue to the diagnosis of acute infectious mononucleosis.

OBJECTIVE: To describe the morphology and significance of apoptotic lymphocytes in peripheral blood smears of patients with acute infectious mononucleosis. To our knowledge this has not been previously reported. DESIGN: Peripheral blood smears from 27 patients with a positive heterophile antibody test were collected and reviewed for the presence of apoptotic lymphocytes. Flow cytometry was performed on three cases to document the previously described low expression of bcl-2 in lymphocytes in infectious mononucleosis. Four control patient populations comprising 80 cases were similarly screened for the presence of apoptotic lymphocytes. SETTING: The specimens were collected over a 3-month period in two laboratories at our tertiary care hospital; all specimens were processed according to a standard protocol. PATIENTS: Young adult military recruits and their spouses, military dependent adolescents, and retired military personnel. RESULTS: Twenty-four (88.9%) of 27 peripheral blood smears of patients with acute infectious mononucleosis contained readily identifiable apoptotic lymphocytes. Three (3.75%) of 80 control peripheral blood smears were identified with rare apoptotic lymphocytes, all occurring in patients with viral upper respiratory infections. CONCLUSIONS: The finding of apoptotic lymphocytes in a peripheral blood smear is useful in the differential diagnosis of infectious mononucleosis and neoplastic hematolymphoid processes.