Adenosine A2A receptor blockade prevents memory dysfunction caused by beta-amyloid peptides but not by scopolamine or MK-801

Adenosine A2A receptor antagonists alleviate memory deficits caused by aging or by administration of beta-amyloid peptides in rodents, which is in accordance with the beneficial effects of caffeine consumption (an adenosine receptor antagonist) on memory performance in aged individuals and in preventing Alzheimer's disease. We now tested if A2A receptor blockade affords a general beneficial effect in different experimental paradigms disturbing memory performance in rodents. The beta-amyloid fragment present in patients with Alzheimer's disease (Abeta1-42, 2 nmol, icv) decreased spontaneous alternation in the Y-maze after 15 days (29%) to an extent similar to the decrease of memory performance caused by scopolamine (2 mg/kg, ip) or MK-801 (0.25 mg/kg, ip) after 30 min (28% and 39%, respectively). The selective A2A receptor antagonist SCH58261 (0.05 mg/kg, ip every 24 h, starting 30 min before the noxious stimuli) prevented Abeta1-42-induced amnesia, but failed to modify scopolamine- or MK-801-induced amnesia. Similar conclusions were reached when testing another A2A receptor antagonist (KW6002, 3 mg/kg, ip). These results indicate that A2A receptors do not affect general processes of memory impairment but instead play a crucial role restricted to neurodegenerative conditions involving an insidious synaptic deterioration leading to memory dysfunction.     

Effectiveness of seatbelts in mitigating traumatic brain injury severity

INTRODUCTION Over the past few decades,traumatic brain injuries(TBIs)have become one of the leading causes of death and the leading cause of injury-related death in the USA.[1,2]It is estimated that 1.70 million people are subject to TBIs each year.[2]Males are more likely to sustain TBIs(59%);the most common age groups are 0–5 years,15–19 years,and>65 years.[2]Approximately 1.36 million people present to the emergency department(ED),275,000 are admitted to the hospital,and 52,000 people die from TBIs.[2]The leading causes of TBIs are falling(35.2%),motor vehicle collisions(MVCs,17.3%),struck by/against an object(16.5%),and assault(10.0%).[2]These statistics combine to make TBIs the leading cause of injury-related death in the USA at 30.5%.[2]It has been estimated that,with specifi c guidelines from the Brain Trauma Foundation,up to 50.0%of the 52,000 TBIrelated deaths may be prevented.[3]     

Complete genome sequence and analysis of Wolinella succinogenes

To understand the origin and emergence of pathogenic bacteria, knowledge of the genetic inventory from their nonpathogenic relatives is a prerequisite. Therefore, the 2.11-megabase genome sequence of Wolinella succinogenes, which is closely related to the pathogenic bacteria Helicobacter pylori and Campylobacter jejuni, was determined. Despite being considered nonpathogenic to its bovine host, W. succinogenes holds an extensive repertoire of genes homologous to known bacterial virulence factors. Many of these genes have been acquired by lateral gene transfer, because part of the virulence plasmid pVir and an N-linked glycosylation gene cluster were found to be syntenic between C. jejuni and genomic islands of W. succinogenes. In contrast to other host-adapted bacteria, W. succinogenes does harbor the highest density of bacterial sensor kinases found in any bacterial genome to date, together with an elaborate signaling circuitry of the GGDEF family of proteins. Because the analysis of the W. succinogenes genome also revealed genes related to soil- and plant-associated bacteria such as the nif genes, W. succinogenes may represent a member of the epsilon proteobacteria with a life cycle outside its host.     

DNA repair polymorphisms associated with cytogenetic subgroups in B‐cell chronic lymphocytic leukemia

Genetic polymorphisms in DNA repair genes can affect the risk of developing different forms of cancer. Therefore, we have studied the putative association of seven single nucleotide polymorphisms (SNPs) in five DNA repair genes with the incidence of chronic lymphocytic leukemia (CLL). We included 461 CLL patients and the same number of age‐ and sex‐matched controls. As chromosomal aberrations are important prognostic markers in CLL, we additionally correlated the SNPs with the occurrence of favorable and unfavorable cytogenetic aberrations in CLL patients. Patients with del(13q) as a sole aberration were allocated to the favorable cytogenetic risk group, and patients with del(17p) and/or del(11q) to the unfavorable cytogenetic risk group. All investigated SNPs were equally distributed between patients with the favorable cytogenetic aberration and controls. However, differences were observed in the distribution of rs13181 in ERCC2 between all CLL patients and controls. Moreover, the clearest differences were found for rs13181 in ERCC2 and rs25487 in XRCC1 between CLL patients with unfavorable cytogenetic aberrations and controls. These data suggest that inborn genetic polymorphisms may predict the outcome of CLL. © 2009 Wiley‐Liss, Inc.     

Physiology of meiosis-activating sterol: endogenous formation and mode of action

BACKGROUND: In the context of mammalian oocyte maturation, it has been suggested that intermediates of cholesterol biosynthesis may represent the physiological signal that instructs the oocyte to reinitiate meiosis. METHODS: Endogenous levels of follicular fluid meiosis-activating sterol (FF-MAS) were monitored in rabbit ovarian tissue, and the influence of exogenous gonadotrophins on sterol formation was assessed. The involvement of cAMP in FF-MAS-induced versus spontaneous oocyte maturation in vitro in mice was also investigated, as was the direct microinjection of FF-MAS into mouse oocytes. RESULTS: Levels of FF-MAS in rabbit ovaries were significantly elevated 1 h after hCG/LH induction and remained so for 4 and 12 h after induction. In naked oocytes undergoing spontaneous maturation, a significant decrease in cAMP was detected after 30 min of culture. However, FF-MAS-mediated induction of oocyte maturation in hypoxanthine-arrested naked oocytes was not associated with any detectable decrease in intracellular cAMP levels. Microinjected FF-MAS failed to induce any noticeable meiosis. CONCLUSIONS: A rapid increase in FF-MAS level occurred in vivo in the rabbit ovary in response to LH, and clear differences were seen in the cAMP pattern during spontaneous and induced oocyte maturation in mice.     

Proteomic analysis of field cancerization in pharynx and oesophagus: a prospective pilot study

‘Field cancerization’ in head and neck squamous cell carcinoma (HNSCC) is poorly understood and it may extend from the pharynx into the oesophagus. Both local recurrences and second primary carcinomas/second field tumours may originate from field cancerization. Our prospective pilot study aimed at the identification of patients suffering from field cancerization on the basis of mucosal protein profiles. Five mucosal biopsies from the oropharynx, hypopharynx and from three regions of the oesophagus were taken from 24 patients. Protein profiles were generated from the mucosal biopsies. After classifier learning, using the profiles of the patients without tumour diagnosis (n = 9), we were able to discriminate between the different mucosal sites and between healthy mucosa and HNSCC using tumour and healthy tissue samples. Mucosal biopsies of tumour patients (n = 15) revealed changes in the protein profiles similar to those in the tumours. During 42 months median follow‐up, six tumour patients experienced local recurrences and second field tumours, of which three occurred in the oesophagus. In all six cases, tumour relapse was correctly predicted by altered mucosal protein profiles (p = 0.007, Fisher's exact test, two‐tailed). Consequently, molecular field cancerization had a strong impact on progression‐free survival (p = 0.007, log‐rank test). Protein profiles of small diagnostic biopsies hold great promise to improve personalized risk assessment in HNSCC. Larger studies are needed to further substantiate these findings. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Functional PMS2 hybrid alleles containing a pseudogene‐specific missense variant trace back to a single ancient intrachromosomal recombination event

Sequence exchange between PMS2 and its pseudogene PMS2CL, embedded in an inverted duplication on chromosome 7p22, has been reported to be an ongoing process that leads to functional PMS2 hybrid alleles containing PMS2‐ and PMS2CL‐specific sequence variants at the 5′‐and the 3′‐end, respectively. The frequency of PMS2 hybrid alleles, their biological significance, and the mechanisms underlying their formation are largely unknown. Here we show that overall hybrid alleles account for one‐third of 384 PMS2 alleles analyzed in individuals of different ethnic backgrounds. Depending on the population, 14–60% of hybrid alleles carry PMS2CL‐specific sequences in exons 13–15, the remainder only in exon 15. We show that exons 13–15 hybrid alleles, named H1 hybrid alleles, constitute different haplotypes but trace back to a single ancient intrachromosomal recombination event with crossover. Taking advantage of an ancestral sequence variant specific for all H1 alleles we developed a simple gDNA‐based polymerase chain reaction (PCR) assay that can be used to identify H1‐allele carriers with high sensitivity and specificity (100 and 99%, respectively). Because H1 hybrid alleles harbor missense variant p.N775S of so far unknown functional significance, we assessed the H1‐carrier frequency in 164 colorectal cancer patients. So far, we found no indication that the variant plays a major role with regard to cancer susceptibility. Hum Mutat 31:1–8, 2010. © 2010 Wiley‐Liss, Inc.