Alterations in mammalian target of rapamycin signaling pathways after traumatic brain injury.

In response to traumatic brain injury (TBI), neurons initiate neuroplastic processes through the activation of intracellular signaling pathways. However, the molecular mechanisms underlying neuroplasticity after TBI are poorly understood. To study this, we utilized the fluid-percussion brain injury (FPI) model to investigate alterations in the mammalian target of rapamycin (mTOR) signaling pathways in response to TBI. Mammalian target of rapamycin stimulates mRNA translation through phosphorylation of eukaryotic initiation factor 4E binding protein-1 (4E-BP1), p70 ribosomal S6 kinase (p70S6K), and ribosomal protein S6 (rpS6). These pathways coordinate cell growth and neuroplasticity via dendritic protein synthesis. Rats received sham surgery or moderate parasagittal FPI on the right side of the parietal cortex, followed by 15 mins, 30 mins, 4 h, 24 h, or 72 h of recovery. Using Western blot analysis, we found that mTOR, p70S6K, rpS6, and 4E-BP1 phosphorylation levels were significantly increased in the ipsilateral parietal cortex and hippocampus from 30 mins to 24 h after TBI, whereas total protein levels were unchanged. Using confocal microscopy to localize these changes, we found that rpS6 phosphorylation was increased in the parietal cortex and all subregions of the hippocampus. In accordance with these results, eIF4E, a key, rate-limiting mRNA translation factor, was also phosphorylated by mitogen-activated protein kinase-interacting kinase 1 (Mnk1) 15 mins after TBI. Together, these results suggest that changes in mRNA translation may be one mechanism that neurons use to respond to trauma and may contribute to the neuroplastic changes observed after TBI.     

Regional Variation and Use of Exception Letters for Cadaveric Liver Allocation in Children with Chronic Liver Disease

The Pediatric End-Stage Liver Disease (PELD) score was designed to reduce subjectivity in liver allocation and to advantage patients with a higher probability of waiting list mortality. The aims of this study were to determine the impact of PELD implementation for children with chronic liver disease and to assess whether PELD met its goal of standardization of liver allocation for children. This study used data reported to the United Network for Organ Sharing (UNOS) registry for children with chronic liver disease receiving primary cadaveric liver transplant between January 2000 and December 2001 (pre-PELD) and March 2002 and July 2003 (PELD). PELD reduced the percentage of children transplanted while in an intensive care unit and as status 1. A calculated PELD score was used for allocation in only 52% of recipients. Thirty percent were status 1 at transplant and PELD scores granted by exception were used for allocation in 18% of patients. There was regional variation in PELD score at allocation and use of exception scores with a significant relationship between PELD score and percentage of exception cases. Regional variation suggests that PELD has not resulted in standardization of listing practices in pediatric liver transplantation.     

Benefits and risks of simvastatin in patients with familial hypercholesterolaemia.

Familial hypercholesterolaemia is a frequent, inherited, monogenic disorder, associated with accelerated development of atherosclerotic disease leading to coronary artery disease. Life expectancy of patients with familial hypercholesterolaemia is reduced by 15-30 years unless they are adequately treated with lipid-lowering therapy. Given the chronic nature of this disease, the selection of a therapeutic approach should be strongly based on its long-term safety and tolerability. The introduction of HMG-CoA reductase inhibitors has revolutionised the treatment of familial hypercholesterolaemia.Simvastatin 40-80 mg/day effectively reduces serum low density lipoprotein (LDL)-cholesterol levels. Furthermore, simvastatin reduces triglycerides and mildly raises high density lipoprotein-cholesterol levels. In addition to the hypolipidaemic effect, other potentially important effects, such as improvement of endothelial function and reduction of LDL oxidation and vascular inflammation, have been associated with HMG-CoA reductase inhibitor therapy. Simvastatin has also been shown to abolish the progression, and even facilitate the regression, of existing human atherosclerotic lesions.The good safety and tolerability profile of simvastatin is clearly highlighted by the low rate of therapy discontinuation observed in several population-based clinical trials. The most common adverse events leading to the discontinuation of therapy are gastrointestinal upset and headache. Asymptomatic elevations in liver transaminase levels and myopathy are uncommon.The overwhelming clinical evidence regarding the long-term use of HMG-CoA reductase inhibitor therapy in patients with familial hypercholesterolaemia together with the long-term safety data (particularly relating to simvastatin) provide support for the use of this drug as a first-line agent when pharmacological treatment is indicated. Early intervention with simvastatin treatment can be successfully implemented with favourable economic benefits.     

Mental object rotation in Parkinson's disease.

Deficits in visual-spatial ability can be associated with Parkinson's disease (PD), and there are several possible reasons for these deficits. Dysfunction in frontal-striatal and/or frontal-parietal systems, associated with dopamine deficiency, might disrupt cognitive processes either supporting (e.g., working memory) or subserving visual-spatial computations. The goal of this study was to assess visual-spatial orientation ability in individuals with PD using the Mental Rotations Test (MRT), along with other measures of cognitive function. Non-demented men with PD were significantly less accurate on this test than matched control men. In contrast, women with PD performed similarly to matched control women, but both groups of women did not perform much better than chance. Further, mental rotation accuracy in men correlated with their executive skills involving mental processing and psychomotor speed. In women with PD, however, mental rotation accuracy correlated negatively with verbal memory, indicating that higher mental rotation performance was associated with lower ability in verbal memory. These results indicate that PD is associated with visual-spatial orientation deficits in men. Women with PD and control women both performed poorly on the MRT, possibly reflecting a floor effect. Although men and women with PD appear to engage different cognitive processes in this task, the reason for the sex difference remains to be elucidated.     

Normal pressure hydrocephalus and cerebral blood flow: a PET study of baseline values.

Regional cerebral blood flow (CBF) was studied with O(15)-water positron emission tomography and anatomic region-of-interest analysis on co-registered magnetic resonance in patients with idiopathic (n = 12) and secondary (n = 5) normal pressure hydrocephalus (NPH). Mean CBF was compared with values obtained from healthy volunteers (n = 12) and with clinical parameters. Mean CBF was significantly decreased in the cerebrum and cerebellum of patients with NPH. The regional analysis demonstrated that CBF was reduced in the basal ganglia and the thalamus but not in white matter regions. The results suggest that the role of the basal ganglia and thalamus in NPH may be more prominent than currently appreciated. The implications for theories regarding the pathogenesis of NPH are discussed.     

Amplified fragment length polymorphism analysis of the VNTR locus D1S80 in central Spain

Summary The polymorphism of the D1S80 locus has been analyzed in a population sample of 203 unrelated individuals living in Madrid (central Spain) by PCR and subsequent semi-dry discontinuous polyacrylamide gel electrophoresis (Tris-chloride/Tris-glycine buffer system) followed by silver staining, The electrophoretic system described in this study offers high resolution in the separation of the different D1S80 alleles allowing the detection of microvariability around the allele T22 in the spanish population. Twenty different alleles containing 17–40 repeats of the basic 16bp unit were distinguished. The alleles T18 and T24 were found to be relatively common in Spain, as in other populations:, with frequencies of 0.224 and 0.372, respectively. No evidence of significant deviations from Hardy-Weinberg equilibrium was found in these preliminary population data.     

Enzymatic synthesis of penicillins

Different penicillins (phenylacetyl, 2-hydroxyphenylacetyl, 4-hydroxyphenylacetyl, phenoxyacetyl and 2-thiopheneacetylpenicillin) have been synthesized "in vitro" by direct N-acylation of 6-aminopenicillanic acid (6-APA) with the acyl group of several acyl-CoA derivatives. The enzyme that catalyzes these reactions, acyl-CoA: 6-APA acyltransferase of Penicillium chrysogenum, was purified to homogeneity (374-fold) and its amino acid composition is given. This protein accepts as substrates several aliphatic acids and different aromatic acids with the only requirement that an acetyl-CoA moiety must be present in the substrate molecule. Shortening or lengthening of the acyl moiety prevents the 6-APA-N-acylation reaction. The presence of an amino group in the alpha-position of the acetyl group does not allow this molecule to be used as substrate. However, different substitutions in the phenyl group (hydroxylation of the carbons 2 and 4) or its replacement by another aromatic ring (thiophene) were accepted with varying reactions rates in the acylation reaction when a 176-fold purified acyltransferase was employed. The homogeneity pure enzyme accepts as substrate thiophene acetyl-CoA but it did not 2-hydroxyphenyl and 4-hydroxyphenylacetyl-CoA. The presence of an oxygen atom between the aromatic and the acetyl moieties did not affect the catalysis.