Neurocognitive dysfunction in children with neurofibromatosis type 1

The cognitive dysfunction associated with neurofibromatosis type 1 (NF1) is an intriguing aspect of this phenotypically heterogeneous genetic neurocutaneous disorder. A broad range of both nonverbal and verbal learning disabilities are evident in approximately 30% to 65% of children with NF1. Deficits in IQ, executive function, attention, and motor skills have also been documented. Current challenges lie in discovering the underlying multifactorial etiologies of the cognitive abnormalities found in NF1. Likely answers lie in neuroanatomic correlates as seen on neuroimaging as well as in molecular and genetic advances into the role of neurofibromin, the protein product of the NF1 gene. The development of NF1 animal models with learning and memory difficulties similar to those seen in humans demonstrates promising preliminary evidence that medical treatment of cognitive abnormalities may one day be possible.     

Comparative effects of carvedilol and metoprolol on left ventricular ejection fraction in heart failure: results of a meta-analysis

BACKGROUND: Both metoprolol and carvedilol improve cardiac function and prolong survival in patients with heart failure. Carvedilol has broader antiadrenergic effects than metoprolol, but it is not clear whether this characteristic is associated with greater benefits on cardiac function during long-term treatment. STUDY DESIGN: We performed a meta-analysis of all 19 randomized controlled trials of carvedilol or metoprolol that measured left ventricular ejection fraction before and after an average of 8.3 +/- 0.1 months of treatment in 2184 patients with chronic heart failure. The mean daily doses were 58 +/- 1 mg of carvedilol and the equivalent of 162 +/- 1 mg of extended-release metoprolol. In the 15 placebo-controlled trials, the mean ejection fraction increased more in the trials of carvedilol than in the trials of metoprolol (placebo-corrected increases of +0.065 and +0.038, respectively), P = .0002. In the 4 active-controlled trials that compared metoprolol directly with carvedilol, the mean ejection fraction also increased more in the carvedilol groups than in the metoprolol groups (+0.084 on carvedilol and +0.057 on metoprolol, respectively), P = .009. The difference in favor of carvedilol in the active-controlled trials was nearly identical to the difference observed in the placebo-controlled trials and was apparent in patients with and without coronary artery disease. CONCLUSION: Long-term treatment with carvedilol produces greater effects on left ventricular ejection fraction than metoprolol when both drugs are prescribed in doses similar to those that have been shown to prolong life.     

Altered response to ibutilide in a heart failure model

OBJECTIVE: Despite the frequent use of anti-arrhythmic drugs in the general population, the electrophysiologic effects of these agents have not been elucidated in congestive heart failure (CHF). METHODS: To examine the impact of left ventricular dysfunction on actions of type III anti-arrhythmic drugs, we evaluated the actions of ibutilide in a canine model of pacing-induced dilated cardiomyopathy. Following ablation of the atrioventricular node, effects on action potential duration at 90% (APD(90)) were compared in vivo, between eight CHF animals and seven controls. Monophasic action potential recordings were obtained from right and left ventricular endocardium/epicardium during and after three doses of ibutilide (0. 01, 0.02 and 0.05 mg/kg), at pacing cycle lengths of 300-1000 ms. RESULTS: APD(90) prolongation with ibutilide (0.01 mg/kg) was significantly greater in CHF vs. controls (P=0.0026, ANOVA). However, plasma ibutilide levels at this dose, were not significantly different between the two groups. In CHF, maximal effects were observed at the lowest dose, whereas effects were gradual and dose-dependent in controls. With ibutilide administration (0.01 mg/kg), an increased dispersion of left-right ventricular APD(90) was observed in CHF, but not in controls (P=0.03). A trend was observed, for increased incidence of non-sustained polymorphic ventricular tachycardia in CHF. CONCLUSIONS: In the presence of CHF, the actions of ibutilide are altered significantly. These findings may reflect altered tissue effects, as a consequence of myocardial electrical remodeling in CHF.     

Lycopene inhibits the growth of normal human prostate epithelial cells in vitro

Lycopene has repeatedly been shown to inhibit the growth of human prostate cells in vitro. However, previous studies with lycopene have focused on cancer specimens, and it is still unclear whether this carotenoid affects the growth of normal human prostate cells as well. Therefore, we investigated the effects of lycopene on normal human prostate epithelial cells (PrEC) by treating them with synthetic all-E-lycopene (up to 5 micromol/L) and assessing proliferation via [3H]thymidine incorporation. The effects of lycopene on cell cycle progression were investigated via flow cytometry. To elucidate whether lycopene modulates cyclins involved in cell cycle progression, protein expressions of cyclins D1 and E were analyzed. The results show that lycopene significantly inhibited the growth of PrEC in a dose-dependent fashion. Flow cytometry revealed a significant cell cycle arrest in the G0/G1 phase. This effect was confirmed by inhibition of cyclin D1 protein expression, whereas cyclin E levels remained unchanged. The results demonstrate that lycopene inhibits growth of nonneoplastic PrEC in vitro. We hypothesize that lycopene might likewise inhibit the growth of prostatic epithelial cells in vivo. This might have an effect on prostate development and/or on enlargement of prostate tissue as found in benign prostate hyperplasia, a potential precursor of prostate cancer.     

Cellular and mitochondrial changes in glutamate-induced HT4 neuronal cell death

Elevated levels of extracellular glutamate are neurotoxic. The cytotoxic property of extracellular glutamate is known to mediate two primary mechanisms, excitotoxicity and excitotoxicity-independent processes. The excitotoxicity-independent pathway was investigated in the current study in a mouse hippocampal-derived HT4 cell line. Exposure of HT4 cells to glutamate for 12h induced loss of cell viability preceded by rapid loss of intracellular reduced glutathione followed by accumulation of intracellular reactive oxygen species, elevation of intracellular Ca(2+), progressive loss of mitochondrial membrane potential swelling and loss of mitochondrial outer membrane integrity. Glutamate-induced loss of DNA integrity has been detected. The antioxidants alpha-tocopherol and trolox, mitochondrial calcium uniporter inhibitor Ruthenium Red and protein synthesis inhibitor cycloheximide all showed protection against glutamate-induced toxicity. None of the protective agents except for alpha-tocopherol controlled the glutamate-induced reactive oxygen species build-up. However, these cell death regulators prevented the glutamate-induced mitochondrial damage and regulated glutamate-induced increase in intracellular Ca(2+). Carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone, a mitochondrial uncoupler, partially protected against glutamate-induced cell death and mitochondrial damage, while the mitochondrial ribosomal inhibitor chloramphenicol and extracellular Ca(2+) chelator ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid did not protect the cells against glutamate treatment.The results of this study demonstrated that mitochondrial dysfunction was a key event in the excitotoxicity-independent component of neuronal cell death. Reactive oxygen species accumulation and glutathione depletion were prominent in glutamate-treated cells; however, these events were not direct mediators of cell death.     

Medulloblastoma: clinical and biologic aspects

Medulloblastoma is the most common childhood primary CNS tumor, and treatment approaches have evolved over the past three decades. The biologic underpinnings of medulloblastoma are not fully characterized, but recent work has identified new, important directions for research. Stratification of patients with medulloblastoma into risk groups is the backbone of most ongoing therapeutic studies. Patients are usually characterized as being either average risk or poor risk, although an intermediate risk group may exist. Standard treatment for older children with medulloblastoma consists of radiation and, for most, chemotherapy. Children with nondisseminated disease at the time of diagnosis have been reported to have as high as an 80% five-year disease-free survival rate after treatment with reduced dose (2340 cGy) craniospinal irradiation, local boost radiation therapy (5500 cGy), and chemotherapy, given during and after radiation therapy. Preradiation chemotherapy has yet to be shown to be of benefit for children with medulloblastoma. Children with disseminated disease are a highly problematic subgroup of patients to treat. A variety of new approaches are being studied, most of which are intensifying chemotherapy either prior to or after radiation. Long-term survivors of medulloblastoma are at significant risk for permanent endocrinologic, cognitive, and psychological sequelae. Infants and very young children with medulloblastoma remain a difficult therapeutic challenge because they have the most virulent form of the disease and are at highest risk for treatment-related sequelae.     

Incidence and Outcomes of Pneumonia in Patients With Heart Failure

BackgroundThe incidence of pneumonia and subsequent outcomes has not been compared in patients with heart failure and reduced ejection fraction (HFrEF) and preserved ejection fraction (HFpEF).ObjectivesThis study aimed to examine the rate and impact of pneumonia in the PARADIGM-HF (Prospective Comparison of Angiotensin Receptor-Neprilysin Inhibitor With Angiotensin Converting Enzyme Inhibitor to Determine Impact on Global Mortality and Morbidity in Heart Failure) and PARAGON-HF (Prospective Comparison of ARNI with ARB Global Outcomes in Heart Failure with Preserved Ejection Fraction) trials.MethodsThe authors analyzed the incidence of investigator-reported pneumonia and the rates of HF hospitalization, cardiovascular death, and all-cause death before and after the occurrence of pneumonia, and estimated risk after the first occurrence of pneumonia in unadjusted and adjusted analyses (the latter including N-terminal pro–B-type natriuretic peptide).ResultsIn PARADIGM-HF, 528 patients (6.3%) developed pneumonia after randomization, giving an incidence rate of 29 (95% CI: 27 to 32) per 1,000 patient-years. In PARAGON-HF, 510 patients (10.6%) developed pneumonia, giving an incidence rate of 39 (95% CI: 36 to 42) per 1,000 patient-years. The subsequent risk of all trial outcomes was elevated after the occurrence of pneumonia. In PARADIGM-HF, the adjusted hazard ratio (HR) for the risk of death from any cause was 4.34 (95% CI: 3.73 to 5.05). The corresponding adjusted HR in PARAGON-HF was 3.76 (95% CI: 3.09 to 4.58).ConclusionsThe incidence of pneumonia was high in patients with HF, especially HFpEF, at around 3 times the expected rate. A first episode of pneumonia was associated with 4-fold higher mortality. (Prospective Comparison of Angiotensin Receptor–Neprilysin Inhibitor With Angiotensin-Converting Enzyme Inhibitor to Determine Impact on Global Mortality and Morbidity in Heart Failure [PARADIGM-HF], NCT01035255; Prospective Comparison of ARNI [Angiotensin Receptor–Neprilysin Inhibitor] With ARB [Angiotensin Receptor Blocker] Global Outcomes in Heart Failure With Preserved Ejection Fraction [PARAGON-HF], NCT01920711)     

Resistance to ten different fluoroquinolone antibiotics following in vitro exposures to nalidixic acid

Ten different fluoroquinolone antibiotics were tested against selected Enterobacteriaceae. Against nalidixic acid-resistant clinical isolates, minimal inhibitory concentrations for all 10 drugs were eightfold to 32-fold greater than those against comparable nalidixic acid-susceptible strains. When the latter strains were serially exposed to increasing concentrations of nalidixic acid, susceptibility to all 10 fluoroquinolones decreased as resistance to nalidixic acid and cinoxacin was acquired in vitro.