Temperature-dependent regulation of vocal pattern generator

Vocalizations of Xenopus laevis are generated by central pattern generators (CPGs). The advertisement call of male X. laevis is a complex biphasic motor rhythm consisting of fast and slow trills (a train of clicks). We found that the trill rate of these advertisement calls is sensitive to temperature and that this rate modification of the vocal rhythms originates in the central pattern generators. In vivo the rates of fast and slow trills increased linearly with an increase in temperature. In vitro a similar linear relation between temperature and compound action potential frequency in the laryngeal nerve was found when fictive advertisement calls were evoked in the isolated brain. Temperature did not limit the contractile properties of laryngeal muscles within the frequency range of vocalizations. We next took advantage of the temperature sensitivity of the vocal CPG in vitro to localize the source of the vocal rhythms. We focused on the dorsal tegmental area of the medulla (DTAM), a brain stem nucleus that is essential for vocal production. We found that bilateral cooling of DTAM reduced both fast and slow trill rates. Thus we conclude that DTAM is a source of biphasic vocal rhythms.     

Calcium antagonists and adenine nucleotide metabolism in rat heart

Attempts to identify mechanisms by which calcium antagonists might influence intracellular metabolism have not yet yielded conclusive findings. In this study bepridil, verapamil, nifedipine, and nisoldipine were found to have no influence on the rate of rat heart myosin adenosine triphosphatase or the calcium dependence of myofibrillar adenosine triphosphatase. None of these calcium antagonists alters the rate of reaction of any of the adenine nucleotide catabolic or adenosine salvage enzymes, adenylate kinase, creatine kinase, adenosine kinase, adenosine deaminase, or 5' nucleotidase, in extracts of rat heart. All four compounds, however, reduced, apparently in a non-specific manner, the rate of uptake of adenosine by myocytes isolated from rat heart. It is concluded that calcium antagonists may, through intercalation with the sarcolemmal membrane, inhibit efflux of adenosine formed by catabolism of adenine nucleotides in ischaemic myocytes. This might offer therapeutic advantage since the intracellular concentration of adenosine would thereby be increased, allowing an increased rate of incorporation of adenosine into the adenosine triphosphate pool in reoxygenated myocardium.     

Characterization of digoxin binding and daunorubicin uptake by isolated mature rat cardiac myocytes

Myocytes isolated from ventricular muscle of mature rat heart have been used for characterization of digoxin binding and to establish whether a relationship exists between digoxin binding and uptake of daunorubicin. High- and low-affinity digoxin binding sites have been identified; respectively, 0.9 +/- 0.1 X 10(7) sites/myocyte, Kd 70-77 nM and 7 +/- 2 X 10(7) sites/myocyte, Kd 1.4-1.7 microM. Myocytes accumulate daunorubicin to an intracellular concentration 30-40 times that in the medium. We find no evidence that saturation of digoxin binding sites alters daunorubicin uptake or that daunorubicin influences binding of digoxin. Alteration of sarcolemmal membrane properties is demonstrated by inhibition of amino acid transport reflected in protein synthesis rates. Calmodulin activation of phosphodiesterase appears insensitive to daunorubicin.     

Current therapeutic strategies in cardiac amyloidosis

Optional statement Amyloidosis is a systemic disease in which clinical manifestations are caused by the replacement of normal tissue with insoluble amyloid fibrils. Cardiac involvement causes a restrictive cardiomyopathy and is associated with poor functional outcomes. Cardiac magnetic resonance imaging and measurement of B-type natriuretic peptide are particularly helpful in distinguishing restrictive cardiomyopathy from constrictive pericarditis, but a tissue biopsy is required to make the diagnosis of amyloidosis. Although standard treatment options for congestive heart failure may provide symptomatic relief in cardiac amyloidosis, prognosis remains dismal. Judicious diuretic use remains the mainstay of therapy, but achieving optimal fluid balance is difficult because patients are usually “preload dependent.” Angiotensin-converting enzyme inhibitors in low doses are often helpful but may lead to orthostatic hypotension, particularly in patients who also have involvement of the autonomic nervous system. β Blockers may be useful if given relatively early in the disease process, but should be used with caution in patients with advanced disease because they may exacerbate symptoms. Therapy aimed at the underlying disease process in primary systemic amyloidosis is based on treatment regimens used in multiple myeloma, such as melphalan and prednisone. These offer limited benefit when cardiac involvement is significant, but newer treatments, including the novel anthracycline 4′-iodo-4′-deoxydoxorubicin, potentially combined with autologous stem cell transplantation, offer some hope for the future.     

Search for new prototypes for the chemotherapy of filariasis: a chemotherapeutic and biochemical approach

The antifilarial activity of two coumarin derivatives (A, B) and three glycosyl amine derivatives (D, E, F) was evaluated against a subperiodic strain of human lymphatic filarial parasite Brugia malayi by the intraperitoneal route at 50 mg/kg for 5 consecutive days. Of these, the two sugar derivatives (D and E) were selected for evaluation by the oral route based on their microfilaricidal (mild), macrofilaricidal and female worm sterilization efficacy using the i.p. route of administration. Compound E was finally selected for combination therapy on the basis of its microfilaricidal and embryostatic action by the oral route and its spectrum of activity against micro- and macrofilariae including embryostatic activity by the i.p. route. In addition, E also significantly inhibited the parasite DNA topoisomerase II. Compound A, in contrast, led to an enhanced adult worm burden. Compound B was toxic by the i.p. route, killing all of the treated animals before completion of the experiment. Some of these compounds demonstrated significant antifilarial efficacy of varying degree when tested in vitro Compounds B, D and F also killed adult B. malayi in vitro at 100 M while 50 M resulted in very slow motility of worms. Compound E in combination with a promising macrofilaricidal benzopyran derivative reported by us recently (compound C) did not show any synergistic or additive effect. These two compounds (C and E) individually on oral administration with either DEC or ivermectin significantly improved microfilaricidal efficacy in terms of intensity and duration of suppressed microfilaraemia. The combination of DEC with compound E demonstrated marginal enhancement in adulticidal efficacy, however, the embryostatic effect of the duo was significantly higher than that exerted by the individual agents. It may thus be inferred that in the absence of an adulticidal antifilarial drug, the use of potential antifilarials in combination with the standard filaricides may yield better results.     

Evaluation of COPD Treatments: A Multicriteria Decision Analysis of Aclidinium and Tiotropium in the United States

Background

Comparisons of the use of aclidinium bromide and tiotropium bromide for the treatment of chronic obstructive pulmonary disease often concentrate on key end points (exacerbations) at the expense of other benefits and risks. Multicriteria decision analysis (MCDA) can help overcome this by using stakeholder preferences to combine multiple end points into an overall value estimate.

Risk of death and myocardial infarction in patients with peripheral arterial disease undergoing percutaneous coronary intervention (from the National Heart, Lung and Blood Institute Dynamic Registry)

Patients with peripheral arterial disease (PAD) undergoing percutaneous coronary intervention (PCI) are at high risk for adverse cardiovascular events. Trends over time in outcomes with advances in PCI and medical therapy are unknown. We evaluated 866 patients with PAD in the National Heart, Lung, and Blood Institute (NHLBI) Dynamic Registry undergoing PCI according to treatment eras: the early bare metal stent (BMS) era (wave 1, 1997 to 1998, n = 180), the BMS era (waves 2 and 3, 1999 and 2001 to 2002, n = 339), and the drug-eluting stent (DES) era (waves 4 and 5, 2004 and 2006, n = 347). We compared in-hospital and 1-year outcomes by recruitment era. In-hospital coronary artery bypass graft surgery rates were significantly lower in the later eras (3.9%, 0.9%, and 0.6% for the early BMS, BMS, and DES eras, respectively, p for trend = 0.005), and an increasing percentage of patients were discharged on aspirin, β blockers, statins, and thienopyridines (p for trend <0.001 for all comparisons). Cumulative 1-year event rates in patients with PAD in the early BMS era, BMS era, and DES era for death were 13.7%, 10.5%, and 9.8% (p for trend = 0.21), those for myocardial infarction (MI) were 9.8%, 8.8%, and 10.0% (p for trend = 0.95), and those for repeat revascularization were 26.8%, 21.0%, and 17.2% (p for trend = 0.008). The 1-year adjusted hazard ratios of adverse events in patients with PAD using the early BMS era as the reference were 0.84 for death in the BMS era (95% confidence interval [CI] 0.46 to 1.55, p = 0.58) and 1.35 in the DES era (95% CI 0.71 to 2.56, p = 0.36), 0.89 for MI in the BMS era (95% CI 0.48 to 1.66, p = 0.72) and 1.02 in the DES era (95% CI 0.55 to 1.87, p = 0.95), and 0.63 for repeat revascularization in the BMS era (95% CI 0.41 to 0.97, p = 0.04) and 0.46 in the DES era (95% CI 0.29 to 0.73, p = 0.001). In conclusion, despite significant improvements in medical therapy and a decrease in repeat revascularization over time, patients with PAD who undergo PCI have a persistent high rate of death and MI.     

Gedunin and photogedunin of Xylocarpus granatum possess antifilarial activity against human lymphatic filarial parasite Brugia malayi in experimental rodent host

The present study is aimed to evaluate antifilarial activity of Xylocarpus granatum (fruit from Andaman) against human lymphatic filarial parasite Brugia malayi in vivo. The in vitro antifilarial activity has already been reported earlier for this mangrove plant which has traditionally been used against several ailments. Aqueous ethanolic crude extract, four fractions (ethyl acetate fraction, n-butanol fraction, water-soluble fraction and water-insoluble fraction) and pure molecule/s of X. granatum (fruit) were tested in vitro on adult worms and microfilariae (mf) of B. malayi and the active samples were further evaluated in vivo in B. malayi (intraperitoneally) i.p. transplanted in the jird model (Meriones unguiculatus) and Mastomys coucha subcutaneously infected with infective larvae (L3). The crude aqueous ethanolic extract was active in vitro (IC50: adult = 15.46 μg/ml; mf = 13.17 μg/ml) and demonstrated 52.8% and 62.7% adulticidal and embryostatic effect on B. malayi, respectively, in Mastomys at a dose of 5 × 50 mg/kg by oral route. The antifilarial activity was primarily localized in the ethyl acetate-soluble fraction which revealed IC50 of 8.5 and 6.9 μg/ml in adult and mf, respectively. This fraction possessed moderate adulticidal and embryostatic action in vivo in Mastomys. Out of eight pure molecules isolated from the active fraction, two compounds gedunin (IC50 = 0.239 μg/ml, CC50 = 212.5 μg/ml, SI = 889.1) and photogedunin (IC50 = 0.213 μg/ml, CC50 = 262.3 μg/ml, SI = 1231.4) at 5 × 100 mg/kg by subcutaneous route revealed excellent adulticidal efficacy resulting in to the death of 80% and 70% transplanted adult B. malayi in the peritoneal cavity of jirds respectively in addition to noticeable microfilaricidalo action on the day of autopsy. The findings reveal that the extract from the fruit X. granatum contains promising in vitro and in vivo antifilarial activity against human lymphatic filarial parasite B. malayi which could be attributed to the presence of two pure compounds gedunin and photogedunin.     

Therapeutic potential of 7,8-dimethoxycoumarin on cisplatin- and ischemia/reperfusion injury-induced acute renal failure in rats

This study was designed to investigate the role of 7,8-dimethoxycoumarin on cisplatin- and ischemia/reperfusion (I/R)-induced acute renal failure in rats. Acute renal failure was induced in rats by administration of a single dose of cisplatin (CP) (6 mg/kg, intraperitoneally on day 6) and occlusion of the left renal artery for 45 min (I) and opened for the next 24 h (R). The drug samples of 7,8-dimethoxycoumarin (DMC, 50, 75, and 100 mg/kg) and cyclosporin A (50 μM/kg) were administered orally for six consecutive days. Administration of a single dose of cisplatin and I/R event has significantly raised blood urea nitrogen and creatinine, N-acetyl beta-D: -glucosaminidase, and thiobarbituric acid reactive substances but decreased FrNa, creatinine clearance, reduced glutathione (GSH), mitochondrial cytochrome c oxidase, and adenosine triphosphate levels. Further, pretreatment of DMC (50, 75, and 100 mg/kg, p.o., for six consecutive days) has ameliorated the CP- and I/R-induced biochemical and histopathological changes in a dose-dependent manner. Furthermore, 75 and 100 mg/kg of 7,8-dimethoxycoumarin has shown to possess the significant renoprotective effect similar to that of the cyclosporin A-treated group which served as positive control. Based on the results of the present study, it has been concluded that 7,8-dimethoxycoumarin protects the kidney against the CP and I/R injury via antioxidant, anti-inflammatory, and inactivation of mitochondrial permeability transition pore opening.