Solution structure of a Na cation stabilized DNA quadruplex containing G.G.G.G and G.C.G.C tetrads formed by G-G-G-C repeats observed in adeno-associated viral DNA

We have applied NMR and molecular dynamics computations including intensity based refinement to define the structure of the d(G-G-G-C-T4-G-G-G-C) dodecanucleotide in 100 mM NaCl solution. The G-G-G-C sequence is of interest since it has been found as tandem repeats in the DNA sequence of human chromosome 19. The same G-G-G-C sequence is also seen as islands in adeno-associated virus, a human parvovirus, which is unique amongst eukaryotic DNA viruses in its ability to integrate site-specifically into a defined region of human chromosome 19. The d(G-G-G-C-T4-G-G-G-C) sequence forms a quadruplex in Na cation containing solution through head-to-tail dimerization of two symmetry-related stem-hairpin loops with adjacent strands antiparallel to each other around the quadruplex. The connecting T4 loops are of the lateral type, resulting in a quadruplex structure containing two internal G.G.G.G tetrads flanked by G.C.G.C tetrads. The G(anti).G(syn).G(anti).G(syn) tetrads are formed through dimerization associated hydrogen bonding alignments of a pair of Hoogsteen G(anti).G(syn) mismatch pairs, while the G(anti).C(anti).G(anti).C(anti) tetrads are formed through dimerization associated bifurcated hydrogen bonding alignments involving the major groove edges of a pair of Watson-Crick G.C base-pairs. The quadruplex contains two distinct narrow and two symmetric wide grooves with extensive stacking between adjacent tetrad planes. The structure of the quadruplex contains internal cavities that can potentially accommodate Na cations positioned between adjacent tetrad planes. Three such Na cations have been modeled into the structure of the d(G-G-G-C-T4-G-G-G-C) quadruplex. Finally, we speculate on the potential role of quadruplex formation involving G.G.G.G and G.C.G.C tetrads during the integration of the adeno-associated parvovirus into its target on human chromosome 19, both of which involve stretches of G-G-G-C sequence elements.     

Parasympathetic neurons in the cranial medial ventricular fat pad on the dog heart selectively decrease ventricular contractility

The present study examined the performance of rats with neurotoxic lesions centred in the thalamic nucleus medialis dorsalis on standard and modified versions of the eight arm radial maze test. In Experiment 1, the thalamic lesions produced a borderline deficit in acquisition of the standard task, but subsequently had no effect when a delay was interposed after the first four arms had been entered. The same lesions had no effect on T-maze alternation, but they did impair radial-arm maze performance when intramaze and extramaze cues were set against each other. In Experiment 2, lesions of the dorsomedial thalamus impaired acquisition of the standard radial-arm maze task, but combining the results from Experiments 1 and 2 showed that this acquisition deficit was confined to those animals in which bilateral damage extended into the adjacent anterior thalamic nuclei. In addition, lesions of the dorsomedial thalamus disrupted radial-arm maze performance when the task was modified to compare working memory and reference memory and increased activity and exploration. These changes were not associated with anterior thalamic damage. Finally, the thalamic lesions did not affect performance on a test of spontaneous object recognition. It is concluded that lesions of medialis dorsalis do not disrupt spatial memory but do affect other processes that can interact with task performance. These include a failure of extramaze cues to overshadow intramaze cues, a change in activity and exploration levels and deficits in with-holding spatial responses.     

A multinational study of the factorial structure and other characteristics of the Dartmouth COOP Functional Health Assessment Charts/WONCA

BACKGROUND: The 'Dartmouth COOP Functional Health Assessment Charts/WONCA' constitute a relatively new derived instrument for assessing health status that is specifically intended for use in primary care on a world-wide basis. It needs further validation in its special area of use. OBJECTIVES: Over a range of countries, social backgrounds and case mixes, our aim was (i) to examine the factorial structure of the instrument; (ii) to explore how well it was understood; (iii) to check its acceptability; and (iv) to assess the value of the pictures on the charts. METHODS: The charts themselves, accompanied by a short questionnaire about the charts, were administered to 1719 patients at eight varied types of treatment centre in Canada, Japan, Nepal and Spain. The responses to the instrument were subjected to standard factor analysis and a special Q-type principal components analysis. The responses to direct questions about the charts were compared with the answers to open-ended questions. RESULTS: Factor analysis suggested a shared factorial pattern for all sites, with the first two factors accounting for 88.5% of the variability in correlations between the charts across the sites. The individual questions were understood by most patients, but a substantial minority did not appear to grasp the underlying purpose of the instrument. The instrument was well accepted. The pictures were considered to be helpful by most respondents, especially those at the Nepal sites. The variability in the scores for the individual charts across sites was less than expected and not always in the expected direction. CONCLUSIONS: The COOP/WONCA system continues to show promise, but needs more validation.     

Urodynamic correlates of resolution of reflux in meningomyelocele patients

PURPOSE: Resolution of reflux in meningomyelocele patients is a reflection of improved bladder storage. We correlated resolution of reflux with changes observed in sequential urodynamic studies. MATERIALS AND METHODS: The study included 27 children with meningomyelocele born between 1975 and 1985 who presented with or developed vesicoureteral reflux. Resolution of reflux was observed during the 10-year followup period as they were treated with a regimen of clean intermittent catheterization and pharmaco-therapy. Urodynamic studies were performed when vesicoureteral reflux was present and subsequent to its resolution. The urodynamic parameters compared in the 2 studies included bladder capacity, pressure specific bladder volume, bladder compliance and leak point pressure. RESULTS: Significant increases in bladder capacity, pressure specific bladder volume and bladder compliance were noted. Leak point pressure appeared to be decreased subsequent to resolution of reflux. CONCLUSIONS: Resolution of reflux in meningomyelocele patients correlates with changes in parameters of bladder storage observed on sequential urodynamic studies.     

The product of the molybdenum cofactor gene mobB of Escherichia coli is a GTP-binding protein

BACKGROUND & AIMS: Efforts to reduce costs in health care may raise concerns about underuse of medical procedures. This study prospectively assessed underuse of upper gastrointestinal endoscopy in a cohort of patients in whom we have recently published data on overuse of endoscopy. METHODS: Underuse was identified by formal necessity criteria for endoscopy, obtained by an explicit panel process. Outpatients were consecutively included in two clinical settings. Setting A consisted of 20 primary care physicians and 7215 patient visits that occurred within 1 month. Setting B consisted of 920 visits that occurred during 3 weeks at an outpatient clinic. RESULTS: During these 8135 visits, 611 patients complained of upper digestive symptoms; 63 of them underwent endoscopy. Underuse was identified in 72 patients (11.8%). The two clinical situations mainly responsible for underuse of endoscopy were uninvestigated peptic symptoms resistant to treatment and dysphagia. At first follow-up, 29 of the patients with initial underuse still fulfilled criteria of necessity (underuse rate, 4.7%). One-year follow-up showed underuse of endoscopy in 5 patients. CONCLUSIONS: This prospective evidence shows that underuse of a medical procedure exists. The estimated overuse and underuse of endoscopy in this cohort were approximately equal (5%). Improving quality of care will require reductions of both overuse and underuse of medical procedures.     

Presenilin 1 regulates the processing of beta-amyloid precursor protein C-terminal fragments and the generation of amyloid beta-protein in endoplasmic reticulum and Golgi

Progressive cerebral deposition of the amyloid beta-protein (Abeta) is believed to play a pivotal role in the pathogenesis of Alzheimer's disease (AD). The highly amyloidogenic 42-residue form of Abeta (Abeta42) is the first species to be deposited in both sporadic and familial AD. Mutations in two familial AD-linked genes, presenilins 1 (PS1) and 2 (PS2), selectively increase the production of Abeta42 in cultured cells and the brains of transgenic mice, and gene deletion of PS1 shows that it is required for normal gamma-secretase cleavage of the beta-amyloid precursor protein (APP) to generate Abeta. To establish the subcellular localization of the PS1 regulation of APP processing to Abeta, fibroblasts from PS1 wild-type (wt) or knockout (KO) embryos as well as Chinese hamster ovary (CHO) cells stably transfected with wt or mutant PS1 were subjected to subcellular fractionation on discontinuous Iodixanol gradients. APP C-terminal fragments (CTF) were markedly increased in both endoplasmic reticulum- (ER-) and Golgi-rich fractions of fibroblasts from KO mice; moreover, similar increases were documented directly in KO brain tissue. No change in the subcellular distribution of full-length APP was detectable in fibroblasts lacking PS1. In CHO cells, a small portion of APP, principally the N-glycosylated isoform, formed complexes with PS1 in both ER- and Golgi-rich fractions, as detected by coimmunoprecipitation. When the same fractions were analyzed by enzyme-linked immunosorbent assays for Abetatotal and Abeta42, Abeta42 was the major Abeta species in the ER fraction (Abeta42:Abetatotal ratio 0.5-1.0), whereas absolute levels of both Abeta42 and Abeta40 were higher in the Golgi fraction and the Abeta42:Abetatoal ratio was 0.05-0.16 there. Mutant PS1 significantly increased Abeta42 levels in the Golgi fraction. Our results indicate PS1 and APP can interact in the ER and Golgi, where PS1 is required for proper gamma-secretase processing of APP CTFs, and that PS1 mutations augment Abeta42 levels principally in Golgi-like vesicles.     

Generalizability of the limits of stability test in the evaluation of dynamic balance among older adults

OBJECTIVE: Reliability of platform posturography tests is essential for the identification and treatment of balance-related disorders. The purposes of this study were to establish the reliability of the limits of stability (LOS) test and to determine the relative variance contributions from identified sources of measurement error. DESIGN: Generalizability theory was used to calculate (1) variance estimates and percentage of variation for the sources of measurement error, and (2) generalizability coefficients. Random effects repeated measures analysis of variance (RM ANOVA) was used to assess consistency of measurements across both days and targets. PARTICIPANTS: Thirty-eight community-dwelling older adults with no recent history of falls. MAIN OUTCOME MEASURES: Outcome measures derived from the LOS tests included movement velocity (MV), maximum center of gravity (COG) excursion (ME), end point COG excursion (EE), and directional control (DC). RESULTS: Estimated generalizability coefficients for 2 and 3 days of testing ranged from .69 to .91. Relative contributions of the day facet were minimal. The RM ANOVA results indicated that for three of the movement variables, no significant differences in scores were observed across days. CONCLUSIONS: The 75% and 100% LOS tests are reliable tests of dynamic balance when administered to healthy older adults with no recent history of falls. Dynamic balance measures were generally consistent across multiple evaluations.     

Altered expression of hMSH2 and hMLH1 in tumors with microsatellite instability and genetic alterations in mismatch repair genes

To date, at least four genes involved in DNA mismatch repair (MMR) have been demonstrated to be altered in the germline of patients with hereditary nonpolyposis colon cancer: hMSH2, hMLH1, hPMS1, and hPMS2. Additionally, loss of MMR function has been demonstrated to lead to the phenomenon of microsatellite instability (MIN) in tumors from these patients. In this study, we have examined the protein expression pattern of hMSH2 and hMLH1 by immunohistochemistry in paraffin-embedded tumors from 7 patients with MIN+ sporadic cancer, 13 patients with familial colorectal cancer, and 12 patients meeting the strict Amsterdam criteria for hereditary nonpolyposis colon cancer. The relationship between the expression of these two gene products, the presence of germline or somatic mutations, and the presence of tumor MIN was examined. Nineteen of the 28 tumors studied demonstrated MIN, whereas mutations in hMLH1 and hMSH2 were detected in 6 and 2 patients, respectively. Of the eight MIN+/mutation+ cases, the absence of protein expression was observed for the corresponding gene product in all but one case (missense mutation in hMLH1). However, seven MIN+/mutation- cases also showed no expression of either hMLH1 (n = 5), hMSH2 (n = 1), or both (n = 1), whereas four MIN+/mutation- cases demonstrated normal expression for both. None of the MIN-/mutation- cases (n = 9) demonstrated an altered expression pattern for either protein. These data suggest that examination of protein expression by immunohistochemistry may be a rapid method for prescreening tumors for mutations in the MMR genes.