Combination therapy with fluconazole and flucytosine in the murine model of cryptococcal meningitis

This study elucidates the role of combined fluconazole and flucytosine as therapy for cryptococcosis in the murine model of meningitis. Three strains of Cryptococcus neoformans for which the range of fluconazole MICs was wide--2 microg/ml (susceptible strain), 8 microg/ml (moderately susceptible strain), and 32 microg/ml (resistant strain)--were used for infection. One day postinfection, the mice were randomized into eight treatment groups: placebo; flucytosine (40 mg/kg of body weight/day); fluconazole at 3 mg/kg/day (low dosage), 10 mg/kg/day (moderate dosage), or 20 mg/kg/day (high dosage); and combined flucytosine and fluconazole at low, moderate, or high doses of fluconazole. Three major findings were demonstrated: (i) correlation between the MICs for the isolates and the in vivo effectiveness of fluconazole as assessed by the reduction in cryptococcal brain burden, (ii) a dose-response curve (a higher dose of fluconazole was significantly more efficacious than a lower dose [P < 0.001]), and (iii) synergism between fluconazole and flucytosine (therapy with a combination of fluconazole and flucytosine was superior to therapy with either agent alone [P < 0.01]).     

Role of passenger leukocytes in allograft rejection: effect of depletion of donor alveolar macrophages on the local production of TNF-alpha, T helper 1/T helper 2 cytokines, IgG subclasses, and pathology in a rat model of lung transplantation

Acute lung allograft rejection is believed to be initiated by passenger leukocytes, such as alveolar macrophages (AM), in the donor organ, which release TNF-alpha, and present alloantigens to host lymphocytes, to up-regulated Th1 cellular and humoral immunity. However, the role of donor AM in local TNF-alpha synthesis, and their ability to induce local Th1 cellular and humoral immunity have not been evaluated. By depleting Brown Norway (BN, RT1n) rat lung allografts of AM before transplantation into Lewis rat (LEW, RT1(1)) recipients, the current study determined the role of donor AM in including the production of TNF-alpha, IFN-gamma (Th1 cytokine), IL-4 (Th2 cytokine), IgG subtypes, and rejection pathology in the allograft. The data show that compared with untreated BN allografts, pretransplant depletion of donor lung AM resulted in significantly less TNF-alpha, and IFN-gamma production in allograft bronchoalveolar lavage fluid with variable effects on local IL-4 production. Depletion of AM in the donor lung before transplantation affected the local production of several IgG subclasses. However, pretransplant depletion of donor AM had no effect on the development of the pathology of severe acute rejection. These data show that donor AM have a central role in the local synthesis of TNF-alpha and induce the production of IFN-gamma and IgG subtypes, locally, during acute lung allograft rejection. However, depletion of AM before transplantation does not prevent the development of severe acute rejection in BN rat lungs, transplanted into LEW recipients.     

Clinical determinants of mortality in patients with angiographically diagnosed ischemic or nonischemic cardiomyopathy

OBJECTIVES: We sought to characterize the clinical determinants of mortality in patients with angiographically diagnosed ischemic or nonischemic cardiomyopathy. BACKGROUND: Patients with ischemic cardiomyopathy may have a worse prognosis than patients with nonischemic cardiomyopathy. Few studies have assessed the effect of ischemic versus nonischemic etiology on outcomes. METHODS: We analyzed prospectively collected data on 3,787 patients with a left ventricular ejection fraction < or = 40% who underwent coronary angiography. Patients were considered to have ischemic cardiomyopathy (n = 3,112) if they had a history of myocardial infarction, percutaneous transluminal coronary angioplasty, coronary artery bypass graft surgery or at least one major epicardial coronary artery with > or = 75% stenosis; all others were considered to have nonischemic cardiomyopathy (n = 675). RESULTS: The median age, ejection fraction and proportion of patients with New York Heart Association functional class III or IV symptoms for the nonischemic and ischemic groups were 55 years versus 63 years, 27% versus 32% and 57% versus 25%, respectively. After adjustment for baseline clinical risk factors and presenting characteristics, ischemic etiology remained an important independent predictor of 5-year mortality (p < 0.0001). The extent of coronary artery disease was a better predictor of survival than ischemic or nonischemic etiology (log likelihood chi-square 700 vs. 675, respectively). CONCLUSIONS: Ischemic etiology is a significant independent predictor of mortality in patients with cardiomyopathy. However, the extent of coronary artery disease contributes more prognostic information than the clinical diagnosis of ischemic or nonischemic cardiomyopathy. Further research is needed to refine the clinical definition of ischemic cardiomyopathy so that physicians can appropriately prescribe treatment and accurately predict outcome.     

Morphometric analysis of heparin coated versus standard intra-aortic balloons

The adverse effects of systemic heparin administration has led to the development of heparin coated devices. Intra-aortic balloons are frequently used in clinical settings in which complications of systemic heparin, especially bleeding, are feared. The current study evaluated the thromboresistance of heparin coated intra-aortic balloons. Six bovine calves were chosen for the experiment. In each animal, three intra-aortic balloons were inserted, and set to the automatic mode: two in the vena cava for 15 min and 45 min, respectively, and one in the aorta for 6 hr. There were nine standard and nine heparin coated intra-aortic balloons. At the end of the procedures, three samples of each intra-aortic balloon were analyzed with scanning electron microscopy for computed analysis of the balloon surface covered with fibrin and cells. The scanning electron microscopy analysis showed no deposit at any time interval on the heparin coated sample surfaces, whereas 3.6% +/- 9.2% (mean +/- SD) of the standard sample surfaces were covered with deposits at 15 min (p = 0.06), 14.8% +/- 24.3% at 45 min (p = 0.01), and 4.4% +/- 12.4% at 6 hr (p = 0.06). Strikingly, none of the 27 heparin coated samples showed any microscopic deposits, whereas 11 of the 27 standard samples did (p < 0.002). Heparin coated intra-aortic balloons appear to be a promising strategy, especially for patients with absolute or relative contraindications to systemic heparinization.     

Heterologous expression of the Kv3.1 potassium channel eliminates spike broadening and the induction of a depolarizing afterpotential in the peptidergic bag cell neurons

The bag cell neurons of Aplysia are a cluster of cells that control egg laying behavior. After brief synaptic stimulation, they depolarize and fire spontaneously for up to 30 min. During the first few seconds of this afterdischarge, the action potentials of the bag cell neurons undergo pronounced broadening. Single bag cell neurons in culture also show spike broadening in response to repeated depolarizations. This broadening is frequency-dependent and associated with the induction of a depolarizing afterpotential lasting minutes. In some neurons the depolarizing afterpotential is sufficient to trigger spontaneous firing. To test the possibility that spike broadening during stimulation is required to trigger the depolarizing afterpotential, we eliminated frequency-dependent broadening by heterologous expression of the Kv3.1 potassium channel. This channel has rapid activation and deactivation kinetics and no use-dependent inactivation. Expression of Kv3.1 prevented spike broadening and also eliminated the depolarizing afterpotential. Measurements of the integral of calcium current during voltage commands, which simulated the action potentials of the control neurons and those expressing Kv3.1, indicate that spike broadening produces up to a fivefold increase in calcium entry. Manipulations that limit calcium entry during action potentials or chelation of intracellular calcium using BAPTA AM prevented the induction of the depolarizing afterpotential. We conclude that spike broadening is essential for the induction of the depolarizing afterpotential probably by regulating calcium influx and suggest that one of the physiological roles of spike broadening may be to regulate long-term changes in neuronal excitability.     

Religiosity and remission of depression in medically ill older patients

PURPOSE: The purpose of this study was to compare the fractional contributions of the three pathways of lactate transport (band 3 system, nonionic diffusion, and monocarboxylate pathway) into red blood cells (RBC) from trained and untrained humans. METHODS: Blood samples were obtained from 19 male subjects: 5 untrained, 5 aerobically-trained, 5 competitive collegiate cross-country runners, and 4 competitive collegiate sprinters. The influx of lactate into the RBC was measured by a radioactive tracer technique using [14C]lactate. Discrimination of each pathway of lactate transport was achieved by using PCMBS (1 mM) to block the monocarboxylate pathway and DIDS (0.2 mM) to block the band 3 system. Nonionic diffusion was calculated as the difference between total lactate influx and the sum of band 3 and monocarboxylate lactate influx. RESULTS: Total lactate influx into the RBC from the more aerobic individuals (trained subjects and cross-country runners) was significantly faster at 1.6 mM lactate concentration ([La]) as compared with the influx into RBC of the untrained subjects. Total influx of lactate was significantly higher (P < 0.05) in the RBC from the sprinters as compared with that in the RBC from the untrained subjects at 41 mM [La]. There were no significant differences among the four groups with regard to the total influx of lactate at 4.1, 8.1, and 20 mM [La]. In general, the percentage of total lactate influx accounted for by each of the three parallel pathways at 1.6, 8.1, and 41.0 mM [La] was not different among the four groups of subjects. CONCLUSIONS: Overall, the groups were more similar than different with regard to RBC lactate influx.