May
14
2009
0

Telavancin: a new lipoglycopeptide for Gram-positive infections.

Telavancin is a lipoglycopeptide derivative of vancomycin. Similar to vancomycin, it demonstrates activity in vitro against a variety of Gram-positive pathogens, including but not limited to methicillin-resistant Staphylococccus aureus (MRSA) and penicillin-resistant Streptococcus pneumoniae (PRSP). Modifications to vancomycin’s structure expanded telavancin’s spectrum of activity in vitro to include organisms such as glycopeptide-intermediate S. aureus (GISA), vancomycin-resistant S. aureus (VRSA) and vancomycin-resistant enterococci (VRE). However, the clinical implications of this are currently unknown. Similar to other glycopeptides, televancin binds to the D-alanyl-D-alanine (D-Ala-D-Ala) terminus in Gram-positive organisms, resulting in inhibition of bacterial cell wall synthesis. In addition, telavancin causes depolarization of the bacterial cell membrane and increased membrane permeability. The resulting activity in vitro is rapidly bactericidal and concentration dependent, with the ratio of area under the time concentration curve to minimum inhibitory concentration (AUC/MIC) as the best predictor of activity in animal models to date. In humans, telavancin exhibits a pharmacokinetic profile that permits once-daily intravenous administration. Doses of 7.5 and 10 mg/kg/day have been studied in clinical trials. The need for dosage adjustments based on age, gender and obesity appear unnecessary. In addition, moderate hepatic impairment does not appreciably alter the pharmacokinetics of the drug. Because telavancin is extensively cleared by the kidneys, dosage adjustments will be required in patients with moderate to severe renal impairment. Published phase II and III clinical trials have shown telavancin to be comparable to standard therapy for the treatment of complicated skin and soft tissue infections. Clinical trials in the treatment of S. aureus bacteremia and hospital-acquired pneumonia are under way. Adverse effects overall appear to be mild and reversible, with taste disturbance, foamy urine, headache, procedural site pain, nausea and vomiting being the most commonly reported. However, renal toxicity was reported more frequently with telavancin than with vancomycin in two phase III clinical trials (3% versus 1%). Prolongation of the corrected QT (QTc) interval has been more common with telavancin than comparator agents, but no clinically significant electrocardiogram (ECG) changes or cardiac abnormalities have been observed to date. Although human pregnancy data is not currently available, animal data revealed limb malformations that were possibly related to telavancin therapy. Therefore, the potential teratogenicity of this agent must be considered in women who are pregnant or may become pregnant. Copyright 2009 Prous Science, S.A.U. or its licensors. All rights reserved.

Written by admin in: Ischemic Brain Damage |
May
14
2009
0

HeartWare miniature axial-flow ventricular assist device: design and initial feasibility test.

Pulsatile ventricular assist devices have successfully provided circulatory support for many patients throughout the past quarter century; however, persistent complications have hindered expanded clinical application of this technology. Although the use of smaller, continuous-flow ventricular assist device pumps has reduced the frequency and severity of some adverse events, design enhancement may further improve outcomes for patients who require long-term left ventricular support. One new product, the HeartWare, Inc., miniature ventricular assist device, features a wide-bladed rotor design in an axial-flow pump with a strong, passively suspended magnetic rotor. The operating range of 16,000 to 28,000 rpm can provide up to 10 L/min of flow. The wide blades portend minimal cellular trauma.This new device has not yet been approved for use in human beings. As a test, we implanted it in a calf, and we continuously monitored the device’s performance and the hemodynamic results over 30 days. No mechanical failure occurred, and no thrombi were noted upon explantation of the device. The animal’s circulation was stable during the test period, and no end-organ abnormalities were found upon autopsy. The potential benefits of this miniature ventricular assist device are its increased availability to a broader patient population, a lower risk of infection, simplified implantation procedures, and improved durability. Further in vivo testing is planned. Herein, we discuss the unique design of the HeartWare miniature ventricular assist device, our feasibility study of its performance, and the possibilities for its use in human beings.

Written by admin in: Ischemic Brain Damage |
May
14
2009
0

Management of complex lipid abnormalities with a fixed dose combination of simvastatin and extended release niacin.

ER niacin combined with simvastatin provides an additional option for achieving LDL-C and non-HDL-C goals for cardiovascular prevention, with greater efficacy in those with triglyceride levels >200 mg/dL. ER niacin 1000 mg combined with simvastatin 20 mg reduced LDL-C by 6%, non-HDL-C by 7%, and triglycerides by 13%, and raised HDL-C by 11% compared to simvastatin 20 mg alone. The 2000 mg dose combined with simvastatin 20 to 40 mg raised reduced LDL-C by 7% to 24%, non-HDL-C by 16% to 28%, and triglycerides by 23% to 34%, and increased HDL-C by 18% to 22% compared to similar dose simvastatin therapy. While cardiovascular risk is reduced in proportion to the magnitude of LDL-C lowering, the additive benefit of raising HDL-C and lowering triglycerides remains to be determined. ER niacin-simvastatin is reasonably well tolerated, with a <7% discontinuation rate due to flushing in patients who used aspirin or non-steroidal anti-inflammatory medications as needed. However, drop-out rates were high in both the simvastatin and ER niacin-simvastatin treatment groups in both the 24- and 52-week studies. The safety profile of the combination appears to be similar to that of niacin and simvastatin used as monotherapies. Results of ongoing morbidity/mortality trials of ER niacin added to statin therapy are eagerly awaited.

Written by admin in: Ischemic Brain Damage |
May
14
2009
0

Color dilution alopecia in a blue Doberman pinscher crossbreed.

A 6-year-old male, blue Doberman pinscher crossbreed was presented with coat abnormalities; in particular, flank alopecia and pruritus. Based on medical the history, clinical evidence, and histopathological examination, color dilution alopecia was diagnosed. The dog was with oral melatonin treated for 3 months without success.

Written by admin in: Ischemic Brain Damage |
May
14
2009
0

Mitochondrial cytochrome c oxidase expression in the central nervous system is elevated at sites of pressure gradient elevation but not absolute pressure increase.

The paucity of suitable experimental models has made it difficult to isolate the pathogenic role of mitochondria in central nervous system diseases associated with absolute pressure elevation and increased pressure gradients. Experimental models of traumatic brain injury (TBI) and hydrocephalus have been useful for examining the mitochondrial response following pressure increase in the central nervous system; however, the presence of multiple pathogenic factors acting on the brain in these previous studies has made it difficult to determine whether the induced changes were a result of mechanical damage, intracranial pressure elevation, or other pathogenic factors. By direct monitoring and control of pressures in the intraocular, intracranial, and vascular compartments, we use the pig optic nerve, a typical central white matter tract, to compare the temporal sequence of cytochrome c oxidase (CcO) levels between regions of absolute pressure elevation and pressure gradient increase. We demonstrate that a rise in pressure gradient without traumatic injury up-regulates CcO levels across the site of the gradient, in a manner similar to what has been previously reported for hydrocephalus. We also demonstrate that CcO changes do not occur following an absolute pressure rise. These findings taken together with our recent reports suggest that mitochondria initiate an early compensatory response to axonal damage following pressure gradient increase. Extrapolation of our results also suggests that decreased CcO levels in TBI may be secondary to mechanical damage. This study emphasises the importance of pressure gradients in regulating mitochondrial function in the central nervous system. (c) 2009 Wiley-Liss, Inc.

Written by admin in: Brain Damage |
May
14
2009
0

Senescence marker protein 30 is up-regulated in kainate-induced hippocampal damage through ERK-mediated astrocytosis.

Senescence maker protein 30 (SMP30) is decreased in an androgen-independent manner in kidney and liver with age. However, regulation of SMP30 expression in the brain has not been examined in aging and neurodegenerative diseases. To investigate SMP30 expression in the brain, we utilized aging and kainate (KA)-induced neurodegenerative disease models. Interestingly, expression of SMP30 was unlikely to decrease in the aged brain, but total levels of SMP30 protein were increased at 4 weeks after KA injury. Increased glial fibrillary acidic protein (GFAP) with elevated SMP30 expression was observed at the same time post-KA, indicating that regulation of SMP30 expression in the brain may be associated with astrocytosis. We confirmed that KA induced GFAP expression with increased SMP30 in rat astrocyte cells. Moreover, we found that ERK1/2 activation was involved in the up-regulation of SMP30 in astrocytes. Our results suggest that elevated SMP30 in activated astrocytes plays an important supportive role after brain damage. (c) 2009 Wiley-Liss, Inc.

Written by admin in: Brain Damage |
May
14
2009
0

Cysteamine prevents inhibition of adenylate kinase caused by cystine in rat brain cortex.

Cystinosis is a systemic genetic disease caused by a lysosomal transport deficiency accumulating cystine in the lysosomes of almost all tissues. Although tissue damage might depend on cystine accumulation, the mechanisms of tissue damage are still obscures. Adenylate kinase, along with creatine kinase, is responsible for the enzymatic phosphotransfer network, crucial for energy homeostasis. Taking into account that cystine is known to inhibit creatine kinase activity, the two enzymes have thiol groups, and the strong interaction between the two activities, our main objective was to investigate the effect of cystine on adenylate kinase activity in the brain cortex of Wistar rats. For the in vivo studies, the animals were injected twice a day with 1.6 mumol/g body weight of cystine dimethylester and/or 0.46 mumol/g body weight of cysteamine from the 25th to the 29th postpartum day and sacrificed after 12 h. Cystine inhibited the enzyme activity in vitro in a concentration dependent way, whereas cysteamine prevented the inhibition. Adenylate kinase activity was found diminished in the brain cortex of rats loaded with cystine dimethylester and co-administration of cysteamine prevented the diminution of the enzyme activity. Considering that adenylate kinase together with creatine kinase is crucial for energy homeostasis, the release of cystine from lysosomes with consequent enzymes inhibition could impair energy homeostasis, contributing to tissue damage in patients with cystinosis.

Written by admin in: Brain Damage |
May
14
2009
0

Mitochondrial DNA deletions of blood lymphocytes as genetic markers of low folate-related mitochondrial genotoxicity in peripheral tissues.

BACKGROUND: A low folate status and mitochondrial DNA (mtDNA) mutations are risk factors for various cancers and degenerative diseases. It is not known if lymphocytic mtDNA deletions can be used as genetic "markers" to reflect global mtDNA damage during folate deficiency. AIM OF THE STUDY: The aim of this study was to characterize folate-related mtDNA deletions in lymphocytes and their associations with mt genotoxicity in peripheral tissues. METHODS: Weaning Wistar rats were fed folate-deficient and folate-replete (control) diets for 2 and 4 weeks. Folate levels of blood lymphocytes and various tissues were assayed by the Lactobacillus casei method. mtDNA deletions were measured by a real-time polymerase chain reaction analysis of whole DNA extracts. RESULTS: Compared to the control counterparts, mtDNA deletions of lymphocytes increased by 3.5-fold (P < 0.05) after 4 weeks of folate deficiency. Lymphocytic mtDNA deletions were inversely associated with plasma (r = -0.619, P = 0.018), red blood cell (r = -0.668, P = 0.009), and lymphocytic folate levels (r = -0.536, P = 0.048). Frequencies of lymphatic mtDNA deletions were positively correlated with mtDNA deletions in tissues including the lungs (r = 0.803, P = 0.0005), muscles (r = 0.755, P = 0.001), heart (r = 0.633, P = 0.015), liver (r = 0.722, P = 0.003), kidneys (r = 0.737, P = 0.006), pancreas (r = 0.666, P = 0.009), and brain (r = 0.917, P < 0.0001). Conclusions: Our data demonstrate that accumulated mtDNA deletions of lymphocytes depended upon dietary folate deprivation. The accumulated mt deletions in lymphocytes closely reflected the mt genotoxicity in the peripheral tissues during folate deficiency.

Written by admin in: Brain Damage |
May
14
2009
0

Chemical and biophysical insights into the propagation of prion strains.

Transmissible spongiform encephalopathies (TSEs) are lethal infectious neurodegenerative diseases. TSEs are caused by prions, infectious agents lacking informational nucleic acids, and possibly identical with higher-order aggregates of the cellular glycolipoprotein PrP(C). Prion strains are derived from TSE isolates that, even after inoculation into genetically identical hosts, cause disease with distinct patterns of protein aggregate deposition, incubation times, morphology of the characteristic brain damage, and cellular tropism. Most of these traits are relatively stable across serial passages. Here we review current techniques for studying prion strain differences in vivo and in cells, and discuss the strain phenomena in the general context of the knowledge gained from modeling prion fibril growth in vitro and in simple organisms.

Written by admin in: Brain Damage |
May
14
2009
0

Psychiatric and substance use disorders comorbidities in veterans with hepatitis C virus and HIV coinfection.

PURPOSE OF REVIEW: A growing number of veterans in theVeterans Health Administration are coinfected with HIV and hepatitis C virus. This review covers timely research relative to comorbid conditions that are common in this population including psychiatric diagnoses, substance use disorders and neurocognitive problems. RECENT FINDINGS: Current literature on the psychiatric, substance use disorders and cognitive problems of the coinfected population show that not only are rates of morbidity higher in the coinfected population but that this affects antiviral treatments as well. There is new evidence that brain injuries and infiltration of the virus into the central nervous system may be responsible for cognitive dysfunction. Cotesting, particularly in hepatitis C infected individuals, is not done routinely despite shared risk factors. SUMMARY: With this understanding of the comorbidities of the coinfected population, integrated healthcare models involving mental health, internal medicine, substance abuse treatment and internal medicine are crucial to work with these medically and psychologically complex patients.

Written by admin in: Brain Damage |

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