Evaluation of a microtiter system for identification of anaerobic bacteria.

The Anaerobe Combo Panel (American MicroScan, Mahwah, N.J.) was evaluated for its ability to identify anaerobic bacteria. The frozen, 96-well panel utilizes 24 biochemical reactions and four antimicrobial agents for species identification. The Anaerobe Combo Panel was used to test 114 clinical isolates of strict anaerobes. Reactions were read after 48 h, and the results were compared with those obtained with the PRAS II system (Scott Laboratories, Inc., Fiskeville, R.I.). Discrepancies between the two systems were resolved by gas-liquid chromatography. With the Anaerobe Combo Panel, 84% of the organisms were able to grow, and 89% of these were correctly identified to genus level and 78% to species level. The Anaerobe Combo Panel was easy to inoculate and read, but some of the reactions were difficult to interpret, and not all of the derived codes were found in the code book.     

Evaluation and management of bleeding during cardiac surgery

Patients undergoing cardiac surgery with and potentially without cardiopulmonary bypass (CPB) are at risk for excessive microvascular bleeding. This bleeding often leads to transfusion of allogeneic blood and blood components as well as reexploration. Excessive bleeding after cardiac surgery occurs because of alterations in the hemostatic system pertaining to dilutional thrombocytopenia, excessive hemostatic activation, and exposure to long-acting antiplatelet or antithrombotic agents. Pharmacologic interventions have been extensively reported as means to attenuate the alterations in the hemostatic system during CPB in an attempt to reduce excessive bleeding, transfusion, and reexploration. Prophylactic administration of agents with antifibrinolytic and antiinflammatory properties can decrease blood loss and transfusion. Aprotinin is the most extensively studied and effective blood conservation agent and has the most potent antifibrinolytic and antiinflammatory effects. Other agents, including the lysine analogues with isolated antifibrinolytic properties, may be effective in low-risk patients. The ability to reduce blood product transfusions and to decrease operative times and reexploration rates favorably affects patient outcomes, availability of blood products, and overall health care costs.     

Muscle temperature and EMG amplitude and frequency during isometric exercise

INTRODUCTION: While muscle temperature is known to vary with environmental temperature and the insulation provided by clothing, little has been published examining the interrelationships between the amplitude and frequency of the electromyogram (EMG), muscle tension, muscle fatigue, and muscle temperature. METHODS: Seven male subjects immersed their arms and legs in water at 24, 27, 34, and 37 degrees C for 20 min. Muscle temperature, strength (maximal voluntary contraction; MVC), endurance for a fatiguing contraction at 40% MVC, and EMG were assessed in the handgrip, biceps brachii, quadriceps, and gastrocnemius muscles. RESULTS: MVC was 44.8% lower for all muscles examined at the coldest muscle temperature. For all temperatures, the relationship between EMG amplitude and tension for brief isometric contractions was nearly linear; however, the increase in the amplitude of the EMG with muscle fatigue was reduced for the coldest muscle temperatures. The frequency components of the EMG and motor unit conduction velocity were largely unaffected by muscle tension but were inversely related to muscle temperature, with a 10 degrees C reduction in temperature resulting in a 32 Hz reduction in the center frequency. During fatiguing contractions at a tension of 40% MVC, the percent reduction in frequency was similar for all muscle temperatures, being reduced by about 20% from the beginning to the end of the contractions. DISCUSSION: EMG amplitude can be used to assess muscle use in most physiological conditions, but the frequency components of the EMG are so related to temperature as to make its use more restricted.     

Metformin-associated respiratory alkalosis

We present an 84-year-old man with a history of chronic obstructive pulmonary disease, type 2 diabetes, hypertension, glaucoma, and bladder cancer who presented to the emergency department after the police found him disoriented and confused. Metformin therapy began 3 days before, and he denied any overdose or suicidal ideation. Other daily medications included glipizide, fluticasone, prednisone, aspirin, furosemide, insulin, and potassium supplements. In the emergency department, his vital signs were significant for hypertension (168/90), tachycardia (120 bpm), and Kussmaul respirations at 24 breaths per minute. Oxygen saturation was 99% on room air, and a fingerstick glucose was 307 mg/dL. He was disoriented to time and answered questions slowly. Metformin was discontinued, and by day 3, the patient's vital signs and laboratory test results normalized. He has been asymptomatic at subsequent follow-up visits. Metformin-associated lactic acidosis is a well-known phenomenon. Respiratory alkalosis may be an early adverse event induced by metformin prior to the development of lactic acidosis.     

Macrophages from lupus-prone MRL mice are characterized by abnormalities in Rho activity, cytoskeletal organization, and adhesiveness to extracellular matrix proteins

Macrophages (mphi) from prediseased mice of the major murine models of lupus have an identical defect in cytokine expression that is triggered by serum and/or apoptotic cells. It is striking that cytokine expression in the absence of serum and apoptotic cells is equivalent to that of nonautoimmune mice. Here, we show that mphi from prediseased lupus-prone MRL/MpJ (MRL/+) or MRL/MpJ-Tnfrsf6(lpr) (MRL/lpr) mice also have reversible abnormalities in morphology, cytoskeletal organization, and adhesive properties. In the presence of serum, MRL mphi adhered in increased numbers to a variety of extracellular matrix proteins compared with mphi from two nonautoimmune strains. However, in the absence of serum, adhesion by MRL mphi was similar to that of nonautoimmune mphi. Increased adhesion by MRL mphi was also observed in the presence of apoptotic, but not necrotic, cells. The morphology and actin-staining pattern of adherent MRL mphi were consistent with reduced activity of Rho, a cytoskeletal regulator. Indeed, MRL mphi cultured in the presence of serum had markedly decreased levels of active Rho compared with nonautoimmune mphi. It is remarkable that when cultured in the absence of serum, MRL mphi displayed normal Rho activity and cytoskeletal morphology. Addition of a Rho inhibitor to normal mphi reproduced the morphologic and cytoskeletal abnormalities observed in MRL mphi. Taken together, our findings support the hypothesis that mphi from MRL and other systemic lupus erythematosus-prone mice have an apoptotic, cell-dependent, autoimmune phenotype that affects a broad range of mphi functions, including cytokine gene expression and Rho-dependent cytoskeletal regulation.     

Airborne infection with Bacillus anthracis--from mills to mail

The lack of identified exposures in 2 of the 11 cases of bioterrorism-related inhalation anthrax in 2001 raised uncertainty about the infectious dose and transmission of Bacillus anthracis. We used the Wells-Riley mathematical model of airborne infection to estimate 1) the exposure concentrations in postal facilities where cases of inhalation anthrax occurred and 2) the risk for infection in various hypothetical scenarios of exposure to B. anthracis aerosolized from contaminated mail in residential settings. These models suggest that a small number of cases of inhalation anthrax can be expected when large numbers of persons are exposed to low concentrations of B. anthracis. The risk for inhalation anthrax is determined not only by bacillary virulence factors but also by infectious aerosol production and removal rates and by host factors.     

The economic benefits of acetylcholinesterase inhibitors for patients with Alzheimer disease and associated dementias

Most cost-effectiveness studies using simulation modeling have demonstrated that donepezil, rivastigmine, and galantamine are cost effective for the treatment of mild-to-moderate Alzheimer disease (AD). These conclusions are in large part based on the assumption that improvement in cognitive status, or prevention of cognitive and functional decline, reduces the amount of time patients spend institutionalized or receiving other full-time care. However, as discussed in this article, outcomes besides delay to institutionalization affect the costs of AD. In reviews of utilization data from Medicare and managed care organizations, it was noted that hospitalization and post acute care in skilled nursing facilities accounted for the largest amount of excess direct costs, even among patients with mild or moderate AD. These utilization reviews also suggest that many patients with AD and related dementias require inpatient care because they are not able to self-manage comorbid conditions. The improvements in cognitive status and daily functioning associated with acetylcholinesterase inhibitor (AChEI) therapy are expected to translate into improved management of comorbidities and reduced caregiver burden, thus reducing the total cost of care. To confirm these and other economic benefits of AChEIs, pharmacoeconomic outcomes should be evaluated routinely as part of randomized, controlled trials and through well-controlled observational studies of AD patients in community and institutional settings.