Effects of acute and chronic methylphenidate on prepulse inhibition: A sex difference study in Wistar rats

BACKGROUND

The utilization of methylphenidate (MPH) is experiencing a notable surge within the adult population. This growth can be attributed to two key factors: its recreational and cognitive enhancement purposes, as well as the rising prevalence of ADHD diagnoses within this population. This study examined acute and chronic oral MPH effects on attention in male and female Wistar rats. To this end, we used a prepulse inhibition (PPI) task, which is widely used to assess psychoactive drug effects in both humans and rodents. This task allowed us to evaluate changes in attention by analyzing sensorimotor gating associated with stimulus selection process.

METHODS

Animals were administered a clinically relevant dose of MPH (5 mg/kg) daily for seven days. The estrous cycle phases of the female rats were measured during behavioral sessions. The PPI task was conducted 20 min after drug administration on day 1 (acute), day 7 (chronic), and 48 h post-treatment.

RESULTS

Results indicated that both acute and chronic MPH treatment impaired PPI expression in male rats, but not in female rats, regardless of their estrous cycle phase. Furthermore, a differential effect of chronic MPH treatment on the PPI task was found in male rats. Specifically, on the seventh treatment day, the PPI effect was observed when animals undertook the PPI task for the first time but was impaired in those animals in which the initial PPI session occurred under the acute influence of the drug (day 1).

CONCLUSIONS

These findings suggest that the impact of MPH on sensorimotor gating responses may vary based on sex and task experience, possibly leading to state-dependent effects in healthy individuals.

Global longitudinal strain to identify low-risk patients with suspected ACS

Funding Acknowledgements

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Albert Einstein Society

Background

Determining which chest pain presentations should be treated and considered an acute coronary syndrome/myocardial infarction (ACS/MI) versus those with non-cardiac chest pain (NCCP) can be difficult. Initial evaluation of suspected ACS requires assessment of presenting symptoms, risk factors, ECG, and cardiac biomarkers. Bedside echocardiography can assist in rapid assessment of suspected ACS through measurement of echocardiographic wall motion score index and left ventricular ejection fraction, though the sensitivity of these measurements has been called into question. Global longitudinal strain (GLS) has been associated with significant CAD and has been found to be more reproducible than LVEF. However, its utility in rapid ED evaluation of chest pain remains under-explored.

Purpose

Assess the utility of speckle-tracking strain in addition to clinical and demographic factors in identification of low-risk patients among those presenting to the ED with suspected ACS.

Methods

This was a retrospective single center study of 434 hospitalized patients aged 18 years or older in whom ACS (excluding STEMI) was suspected by ED assessment, from 9/1/2015 – 12/31/2019. Echocardiography within 24 hours of admission was analyzed, with left ventricular global longitudinal strain (LVGLS) obtained via AutoSTRAIN software (TOMTEC Imaging Systems GmbH). Patients were identified as having NCCP (n = 158, 36%), myocardial injury (n = 110, 25%), or MI (n = 166, 38%; subdivided into NSTEMI [n = 74, 44.6%] and type II MI [n = 92, 55.4%]) according to the 4th universal definition of MI. Mean strain values were compared between study groups using Independent T tests. Logistic regression and ROC analysis was done to determine the value of LVGLS in the prediction of ACS.

Results

Non-white subjects were over-represented in the NCCP group (92% vs 8%), versus the myocardial injury and MI groups (65% vs 35%, p < 0.001), and on average the NCCP group was younger (56.5 ± 14.5 vs 64.8 ± 15, p < 0.001). LVGLS was significantly higher for NCCP versus the MI group (17.7 ± 2.8 vs 14.9 ± 3.9, p < 0.001). ROC analysis (c-statistic = 0.72) identified an optimal cutoff at ≤15.6, with sensitivity of 56% and specificity of 82%. Logistic regression analysis, including demographic and clinical variables, identified age, LVGLS, LV end-diastolic volume and serum creatinine as significant independent predictors for NCCP vs ACS. The addition of these factors in the predictive analysis resulted in slightly improved model performance (c-statistic = 0.78).

Conclusions

LVGLS among patients with suspected ACS is significantly different between NCCP and MI; however, low sensitivity for MI makes it inadequate as a single test to discriminate between the two. Combining LVGLS with other clinical/laboratory factors may have potential utility and will be explored in future work. Abstract Figure. Distribution Plot for LVGLS  Abstract Figure. ROC Curve for LVGLS

Improved upper limits on the stochastic gravitational-wave background from 2009-2010 LIGO and Virgo data

Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the Universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the Universe. We carry out a search for the stochastic background with the latest data from the LIGO and Virgo detectors. Consistent with predictions from most stochastic gravitational-wave background models, the data display no evidence of a stochastic gravitational-wave signal. Assuming a gravitational-wave spectrum of Ω_{GW}(f)=Ω_{α}(f/f_{ref})^{α}, we place 95% confidence level upper limits on the energy density of the background in each of four frequency bands spanning 41.5-1726 Hz. In the frequency band of 41.5-169.25 Hz for a spectral index of α=0, we constrain the energy density of the stochastic background to be Ω_{GW}(f)<5.6×10^{-6}. For the 600-1000 Hz band, Ω_{GW}(f)<0.14(f/900  Hz)^{3}, a factor of 2.5 lower than the best previously reported upper limits. We find Ω_{GW}(f)<1.8×10^{-4} using a spectral index of zero for 170-600 Hz and Ω_{GW}(f)<1.0(f/1300  Hz)^{3} for 1000-1726 Hz, bands in which no previous direct limits have been placed. The limits in these four bands are the lowest direct measurements to date on the stochastic background. We discuss the implications of these results in light of the recent claim by the BICEP2 experiment of the possible evidence for inflationary gravitational waves.

Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

Systematic review with meta-analysis: the incidence of advanced neoplasia after polypectomy in patients with and without low-risk adenomas

BACKGROUND

Patients with one to two tubular adenomas <1 cm in size without high-grade dysplasia (low-risk group) are considered at low risk for colorectal cancer. However, it is uncertain whether they have the same risk of subsequent advanced neoplasia as those with no neoplasia at baseline colonoscopy.

AIM

To compare incidence of metachronous advanced neoplasia between patients in the low-risk adenoma group and those without neoplasia at index colonoscopy.

METHODS

Relevant publications were identified by MEDLINE/EMBASE and other databases for the period 1992-2013. Studies comparing the incidence of post-polypectomy advanced neoplasia (adenomas ≥10 mm/high-grade dysplasia/villous or cancer) between the low-risk group and patients without colorectal neoplasia at the first colonoscopy were included. Detection rates for advanced neoplasia at endoscopic surveillance were extracted. Study quality was ascertained according to Newcastle-Ottawa Scale. Forest plot was produced based on random-effect models. Inter-study heterogeneity was assessed using the I(2) statistic.

RESULTS

Seven studies provided data on 11 387 patients. Mean surveillance periods ranged between 2 and 5 years. Altogether, 267 patients with post-polypectomy advanced neoplasia were detected in the two groups. The incidence of advanced neoplasia was 1.6% (119/7308) in those without neoplasia and 3.6% (148/4079) in those with low-risk adenoma, respectively, corresponding to a relative risk of 1.8 (95% CI: 1.3-2.6). Inter-study heterogeneity was only moderate (I(2) : 37%). No publication bias was present.

CONCLUSIONS

Patients with low-risk adenomas at baseline had a higher risk of metachronous advanced neoplasia than the group with no adenomas at baseline, though the absolute risk was low in both groups.

Constraints on cosmic strings from the LIGO-Virgo gravitational-wave detectors

Cosmic strings can give rise to a large variety of interesting astrophysical phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by cusps are a promising observational signature. In this Letter we present a search for GWs from cosmic string cusps in data collected by the LIGO and Virgo gravitational wave detectors between 2005 and 2010, with over 625 days of live time. We find no evidence of GW signals from cosmic strings. From this result, we derive new constraints on cosmic string parameters, which complement and improve existing limits from previous searches for a stochastic background of GWs from cosmic microwave background measurements and pulsar timing data. In particular, if the size of loops is given by the gravitational backreaction scale, we place upper limits on the string tension Gμ below 10(-8) in some regions of the cosmic string parameter space.

Differential implication of dorsolateral and dorsomedial srtiatum in encoding and recovery processes of latent inhibition

The dorsal striatum has been ascribed to different behavioral roles. While the lateral area (dls) is implicated in habitual actions, its medial part (dms) is linked to goal expectancy. According to this model, dls function includes representation of stimulus-response associations, but not of goals. Dls function has been typically analyzed with regard to movement, and there is no data indicating whether this region could processes specific stimulus-outcome associations. To test this possibility, we analyzed the effects of dls and dms inactivation on the retrieval phase, and dms lesion on the acquisition phase of a latent inhibition procedure using two conditions, long and short presentations of the future conditioned stimulus. Contrary to current theories of basal ganglia function, we report evidence in favor of the dls involvement in cognitive processes of learning and retrieval. Moreover, we provide data about the sequential relationship between dms and dls, in which the dms could be involved, but it would not be critical, in new learning and the dls could be subsequently involved in consolidating cognitive routines.

Colon capsule endoscopy: European Society of Gastrointestinal Endoscopy (ESGE) Guideline

PillCam colon capsule endoscopy (CCE) is an innovative noninvasive, and painless ingestible capsule technique that allows exploration of the colon without the need for sedation and gas insufflation. Although it is already available in European and other countries, the clinical indications for CCE as well as the reporting and work-up of detected findings have not yet been standardized. The aim of this evidence-based and consensus-based guideline, commissioned by the European Society of Gastrointestinal Endoscopy (ESGE) is to furnish healthcare providers with a comprehensive framework for potential implementation of this technique in a clinical setting.

Clinical validation of the European Panel on the Appropriateness of Gastrointestinal Endoscopy (EPAGE) II criteria in an open-access unit: a prospective study

BACKGROUND AND STUDY AIMS

The European Panel on the Appropriateness of Gastrointestinal Endoscopy (EPAGE I) criteria were recently updated (EPAGE II), but no prospective studies have used these criteria in clinical practice. The aim of the current study was to validate the EPAGE II criteria in an open-access endoscopy unit.

PATIENTS AND METHODS

A prospective observational study was conducted in an open-access endoscopy unit at a tertiary care referral center. Consecutive outpatients (n = 1004; mean age 58.9 ± 13.1 years; 45 % men) were referred for diagnostic colonoscopy between September 2009 and February 2010. The appropriateness of colonoscopy was assessed based on EPAGE II criteria, and the relationship between appropriateness and both referral doctor and detection of significant lesions was examined. The effectiveness of EPAGE II criteria in assessing appropriateness was measured by means of sensitivity, specificity, and positive and negative predictive values for detecting significant lesions.

RESULTS

Colonoscopic cecal intubation was achieved in 956 patients (95.2 %). Most referral doctors were gastroenterologists (58.0 %) and the most common indication was colorectal cancer (CRC) screening (35.2 %). EPAGE II criteria were applicable in 968 patients (96.4 %); of these patients, the indication was appropriate in 778 (80.4 %), inappropriate in 102 (10.5 %), and uncertain in 88 (9.1 %). Patients with appropriate or uncertain indications based on EPAGE II criteria had more relevant endoscopic findings than those with inappropriate indications (38.8 % vs. 24.5 %; OR 1.95, 95 %CI 1.22 - 3.13; P < 0.005). Sensitivity and negative predictive value of EPAGE II criteria for detecting significant lesions were 93.1 % (95 %CI 90 % - 96 %) and 75.5 % (95 %CI 67 % - 84 %), respectively, whereas for advanced neoplastic lesions these values were 98.0 % (95 %CI 95 % - 100 %) and 98.0 % (95 % CI 95 % - 100 %), respectively. Adherence to EPAGE II recommendations was an independent predictor of finding a significant lesion (OR 1.93, 95 %CI 1.20 - 3.11; P = 0.007).

CONCLUSIONS

EPAGE II is a simple, valid score for detecting inappropriate colonoscopies in clinical practice.

The changing face of hospitalisation due to gastrointestinal bleeding and perforation

BACKGROUND

Temporal changes in the incidence of cause-specific gastrointestinal (GI) complications may be one of the factors underlying changing medical practice patterns.

AIM

To report temporal changes in the incidence of five major causes of specific gastrointestinal (GI) complication events.

METHODOLOGY

Population-based study of patients hospitalised due to GI bleeding and perforation from 1996 to 2005 in Spain. We report crude rates, and estimate regression coefficients of temporal trends, severity and recorded drug use for five frequent GI events. GI hospitalisation charts were validated by independent review of large random samples.

RESULTS

The incidence per 100 000 person-years of hospitalisations due to upper GI ulcer bleeding and perforation decreased over time [from 54.6 and 3.9 in 1996 (R² = 0.944) to 25.8 and 2.9 in 2005 (R² = 0.410) respectively]. On the contrary, the incidence per 100 000 person-years of colonic diverticular and angiodysplasia bleeding increased over time [3.3 and 0.9 in 1996 (R² = 0.443) and 8.0 and 2.6 in 2005 (R² = 0.715) respectively]. A small increasing trend was observed for the incidence per 100 000 person-years of intestinal perforations (from 1.5 to 2.3 events). Based on data extracted from the validation process, recent recorded drug intake showed an increased frequency of anticoagulants with colonic diverticular and angiodysplasia bleeding, whereas NSAID and low-dose aspirin use were more prevalent in peptic ulcer bleeding and colonic diverticular bleeding respectively.

CONCLUSIONS

From 1996 to 2005, hospitalisations due to peptic ulcer bleeding and perforation have decreased significantly, whereas the number of cases of colonic diverticular and angiodysplasia bleeding have increased.

Effects of context novelty vs. familiarity on latent inhibition with a conditioned taste aversion procedure

The latent inhibition phenomenon is observed when a conditioned stimulus is preexposed without any consequence before conditioning. The result of this manipulation is a reduction in conditioned response intensity to such a stimulus. In this study, we analyse the role of context novelty/familiarity on LI modulation by changing the context using a three-stage conditioned taste aversion procedure. Experiment 1 revealed that, similar to other learning procedures, a context change between preexposure and conditioning/testing (but not between preexposure/conditioning and testing) resulted in LI attenuation when the experimental contexts were novel. Experiment 2, using animals' home cages as one of the contexts, revealed a different pattern of results, with an unexpected increase in LI magnitude when the context change was introduced between conditioning and test stages. The Schmajuk et al. (1996) computational model explains these results in terms of the increased novelty of the conditioned stimulus during preexposure, conditioning, and testing.

Variation among endoscopy units in the achievement of the standards of colonoscopic performance indicators

BACKGROUND/AIMS

To assess the achievement of quality standards of colonoscopy at six endoscopy units.

METHODOLOGY

Three indicators were used to assess the quality of 1056 colonoscopies performed at six hospitals: cecal intubation; adequate colon cleansing; and removal and recovery of all detected polyps. Analyses were performed on the total number of colonoscopies and on colonoscopies in which polyps were actually detected. The accomplishment of each indicator and a global compound index of all three indicators, named the Problem Rate, were analyzed. Results from each endoscopy unit were compared to previously established standards.

RESULTS

Adequate colon cleansing was the most frequent problem for quality in all centers; adequate colon preparation was 67% (range 50 to 84%). The cecum was reached in 84% of all colonoscopies (range 76 to 90%). 75% of all patients (range 28. 79%) had all polyps excised and recovered. All centers had rates below standard for one or several indicators (p<0.01, all cases). Two of the participant hospitals had an overall problem rate above the estimated standard (p<0.01).

CONCLUSIONS

There is a significant variation in the achievement of quality standards of colonoscopy between endoscopy units. Colon cleansing is the most frequent quality problem for colonoscopy.

Effects of long-term cyclo-oxygenase 2 selective and acid inhibition on Barrett's oesophagus

BACKGROUND

There is an overexpression of cyclo-oxygenase 2 (COX-2) in Barrett's oesophagus (BO).

AIM

To determine the long-term effect of a COX-2 inhibitor on cellular mechanisms involved in BO.

METHODS

A randomized controlled trial was conducted in BO patients allocated to continue the usual proton pump inhibitor (PPI) alone treatment, or PPI combined with rofecoxib (25 mg/day) for 6 months. Cell proliferation index and COX-2 expression in BO glands was determined in biopsy specimens at baseline and after treatment. Cell apoptosis, cyclin D1, p53 and vascular endothelial growth factor (VEGF) expression was also explored in a subset of patients. Student-t test and the U-Mann-Whitney test were used for quantitative and ordinal variables.

RESULTS

Of 62 patients, 58 completed the study. A higher proportion of patients on rofecoxib + PPI exhibited a decrease in COX-2 expression compared to those treated with PPI alone, but cell proliferation index was not affected. Unlike PPI alone, rofecoxib + PPI was associated with an increase in the apoptotic cell index, a decrease in p53 cell staining and VEGF expression in mucosal vessels. No effect on low-grade dysplasia or cyclin D1 was observed.

CONCLUSIONS

The addition of rofecoxib to PPI therapy does not affect cell proliferation index in BO cells after 6 months of therapy, but does reduce COX-2 and VEGF expression and increases cell apoptosis.

Risk of upper gastrointestinal ulcer bleeding associated with selective cyclo-oxygenase-2 inhibitors, traditional non-aspirin non-steroidal anti-inflammatory drugs, aspirin and combinations

BACKGROUND

The risks and benefits of coxibs, non-steroidal anti-inflammatory drugs (NSAIDs), and aspirin treatment are under intense debate.

OBJECTIVE

To determine the risk of peptic ulcer upper gastrointestinal bleeding (UGIB) associated with the use of coxibs, traditional NSAIDs, aspirin or combinations of these drugs in clinical practice.

METHODS

A hospital-based, case-control study in the general community of patients from the National Health System in Spain. The study included 2777 consecutive patients with endoscopy-proved major UGIB because of the peptic lesions and 5532 controls matched by age, hospital and month of admission. Adjusted relative risk (adj RR) of UGIB determined by conditional logistic regression analysis is provided.

RESULTS

Use of non-aspirin-NSAIDs increased the risk of UGIB (adj RR 5.3; 95% confidence interval (CI) 4.5 to 6.2). Among non-aspirin-NSAIDs, aceclofenac (adj RR 3.1; 95% CI 2.3 to 4.2) had the lowest RR, whereas ketorolac (adj RR 14.4; 95% CI 5.2 to 39.9) had the highest. Rofecoxib treatment increased the risk of UGIB (adj RR 2.1; 95% CI 1.1 to 4.0), whereas celecoxib, paracetamol or concomitant use of a proton pump inhibitor with an NSAID presented no increased risk. Non-aspirin antiplatelet treatment (clopidogrel/ticlopidine) had a similar risk of UGIB (adj RR 2.8; 95% CI 1.9 to 4.2) to cardioprotective aspirin at a dose of 100 mg/day (adj RR 2.7; 95% CI 2.0 to 3.6) or anticoagulants (adj RR 2.8; 95% CI 2.1 to 3.7). An apparent interaction was found between low-dose aspirin and use of non-aspirin-NSAIDs, coxibs or thienopyridines, which increased further the risk of UGIB in a similar way.

CONCLUSIONS

Coxib use presents a lower RR of UGIB than non-selective NSAIDs. However, when combined with low-dose aspirin, the differences between non-selective NSAIDs and coxibs tend to disappear. Treatment with either non-aspirin antiplatelet or cardioprotective aspirin has a similar risk of UGIB.

Cribado del carcinoma escamoso de esófago en población de riesgo

Together with adenocarcinoma, epidermoid esophageal carcinoma is the most clinically important neoplasm of the esophagus. Because of the low incidence of epidermoid esophageal carcinoma in the general population, strategies for its early diagnosis are not a priority compared with other neoplasms. However, because survival is low when the disease is diagnosed in symptomatic patients (less than 20% at 5 years), methods for its early diagnosis should be investigated. The use of cytology or Lugol chromoendoscopy in countries with a high incidence of epidermoid carcinoma or in individuals at increased risk (mainly alcoholics and smokers) has allowed early diagnosis and potentially curative treatment, substantially increasing life expectancy in this group of patients. These results should stimulate the evaluation and eventual implementation of programs to achieve early diagnosis and therefore greater survival in patients with epidermoid esophageal carcinoma in Western countries.

[Appropriateness of indications for upper gastrointestinal endoscopy in open-access endoscopy units]

INTRODUCTION

The indication for upper gastrointestinal endoscopy (UGE) by the general practitioner may significantly reduce the waiting time list for the exploration and accelerates the process of taking decisions in patients with upper gastrointestinal pathology. The objective of this study is to compare the appropriateness of indications for diagnostic UGE between general practitioners and gastroenterologists in open-access endoscopy units.

PATIENTS AND METHODS

General practitioners were previously updated on the main indications, risks and benefits for UGE, and instructions for submitting patients to open-access units were given. The indications for UGE were analysed by means of the ASGE 1997 and EPAGE guidelines for the appropriate use of upper gastrointestinal endoscopy.

RESULTS

There were no statistical differences between patients referred by general practitioners or gastroenterologists with respect to gender, age, indication of UGE or the presence of alarm symptoms. According to the ASGE guidelines overuse of UGE was observed in 25 (18.4%) of 136 patients submitted by general practitioners and in 32 (18.6%) of 172 patients submitted by gastroenterologists (NS). According to the EPAGE guidelines a non-appropriated UGE was present in 16 (11.8%) of patients referred by general practitioners and by 19 (11%) of patients submitted by gastroenterologists (NS).

CONCLUSION

The level of appropriateness for UGE indication obtained by general practitioners is similar to that reached by gastroenterologists. This finding should be considered for the implementation of open-access endoscopy units in our country.

Genotipo y expresión fenotípica de la hemocromatosis hereditaria en España

INTRODUCTION

The prevalence of C282Y homozygosity in patients with hereditary hemochromatosis (HH) has been reported to be markedly lower in the Mediterranean Basin than in northern Europe. In Spain, the available data are contradictory and limited to small series in specific regions. The objective of this study is to determine the prevalence of the 2 main HFE gene mutations in a large series of unrelated Spanish patients with HH from different geographical origins.

PATIENTS AND METHOD

The criteria for HH diagnosis were: repeat serum transferrin saturation index (> 45% plus C282Y homozygosity and/or hepatic iron index (> 1.9 of dry liver weight in non-cirrhotic patients or (> 4.1 in patients with liver cirrhosis. Cases in related individuals were excluded. Demographic data, clinical expression, iron parameters and HFE gene mutations (C282Y and H63D) were assessed in 222 patients.

RESULTS

A total of 83.3% of patients were C282Y homozygous and 5% were compound heterozygous (C282Y/H63D). No significant differences in phenotypic expression or in the frequency of C282Y homozygosity were observed between patients born in the North and South of Spain.

CONCLUSION

The genotypic and phenotypic expression of HH in Spain is very similar to that reported in Northern Europe. Thus, the genetic heterogeneity described in some Southern European regions cannot be considered a common feature to all countries of the Mediterranean Basin.

Low frequency of upper gastrointestinal complications in a cohort of high-risk patients taking low-dose aspirin or NSAIDS and omeprazole

BACKGROUND

There is very little information available on the incidence of complications and on the best prevention therapy in high-risk patients taking non-steroidal anti-inflammatory drugs (NSAIDs) and/or aspirin. Randomized-controlled trials in such patients are rare for ethical reasons. We studied the incidence of gastrointestinal complications in high-risk patients taking long-term low-dose aspirin or non-aspirin-NSAIDs combined with omeprazole in a real-life clinical setting.

METHODS

This was a multicentre, prospective and observational study including 247 consecutive high-risk patients who had a clinical indication for long-term treatment with either low-dose aspirin or non-aspirin NSAIDs and omeprazole therapy. The occurrence of gastrointestinal complications was measured.

RESULTS

In addition to a recent history of peptic ulcer bleeding, all patients had at least 1 other risk factor and 112 (45.3%) had 3 or more risk factors; 78.9% were taking low-dose aspirin and the remainder non-aspirin NSAIDs. Mean follow-up was 14.6 +/- 10.38 months. Three patients taking low-dose aspirin developed upper gastrointestinal bleeding (1.2%; 95% CI 0.3-3.5; 1.0 event/100 patients/year). This was similar to the rate observed in studies involving non-high-risk patients taking low-dose aspirin and higher than that observed in patients not taking low-dose aspirin. Two additional patients developed a lower gastrointestinal bleeding event (0.81% (0.04%-3.12%); 0.67 events/100 patients/year), which was within the range expected in NSAID users.

CONCLUSIONS

The use of omeprazole in the high-risk patient taking low-dose aspirin or NSAIDs seems to be a safe therapeutic approach in this population and is associated with a low frequency of upper gastrointestinal complications.

Primary molars in severe infraocclusion: a retrospective study

The term severe infraocclusion is used to describe teeth located at the level of or below the alveolar crest and is rare.

AIM

The aims of the study were to evaluate the influence of age of diagnosis and treatment on the outcome of the successors of primary molars with severe infraocclusion and to propose a treatment protocol based on the age of diagnosis.

METHODS

A retrospective study of patients with primary molars in severe infraocclusion (PMSI) in the period 1987-2001 was carried out. Parameters assessed were age, sex, degree of infraocclusion based on radiographs, altered position of adjacent and successor teeth and treatment outcome.

RESULTS

The sample comprised 19 patients with 23 cases of PMSI, all were second primary molars (47.8% maxillary and 52.2% mandibular). Migration of the neighbouring tooth was present in 51.5% of cases. The PMSI treatment was by extraction in all cases, a space maintainer was fitted and remained in place until the eruption of the successor. The outcome was favourable in 82.6% of cases.

CONCLUSION

Successful treatment of PMSI depends on prompt diagnosis and appropriate treatment and follow-up of the cases. The earlier the age of detection, the more favourable the outcome.

[Helicobacter pylori and immunogenetic factors of the host: relevance of the HLADQA1 *0102 and *0301 alleles in peptic ulcer]

AIM

To investigate the potential contribution of the *0102 and *0301 alleles of the HLADQA1 gene in Helicobacter pylori infection and peptic ulcer disease in a Spanish Caucasian population.

PATIENTS AND METHODS

We studied 163 patients with peptic ulcer (117 duodenal ulcers and 46 gastric ulcers; 111 with recent upper gastrointestinal hemorrhage) and 90 controls. The *0102 and *0301 alleles of the HLADQA1 gene were typed by polymerase chain reaction using genomic DNA. H. pylori infection were determined by breath test and/or serology. The cytotoxins CagA and VacA were investigated using serology (Western-blot) in 98 patients and 48 controls with H. pylori infection.

RESULTS

H. pylori infection was found in 94.6% of patients with duodenal ulcer, in 84.4% of those with gastric ulcer and in 67.4% of controls (p < 0.001). The distribution of the *0102 allele of the HLADQA1 gene was similar in patients (31.9%) and in controls (36.7%). The *0301 was more frequent in patients with gastric ulcer (32.6%) than in those with duodenal ulcer (16.2%) (p < 0.05) but no differences were found on comparison with the control group (24.4%). No differences were found when the groups were analyzed according to H. pylori infection, CagA- and VacA-positive strains, consumption of non-steroidal antiinflammatory drugs or previous history of ulcer or hemorrhage.

CONCLUSION

The *0102 and *0301 alleles of the HLADQA1 gene did not alter susceptibility to H. pylori infection or the evolution of peptic ulcer disease in a Caucasian population in Spain.

Hereditary hemochromatosis in Spain

The C282Y mutation of the HFE gene has been reported as the main cause of hereditary hemochromatosis (HH). Another missense mutation (H63D) has also been detected at an increased frequency in a compound heterozygote state with the C282Y mutation in HH patients. However, these two mutations are not present in all of the HH patients, indicating that other mutations in the HFE gene, or in other loci, should exist. The present study reports the frequencies of the C282Y and H63D mutations in 74 Spanish HH patients and the results of the sequencing analysis of the HFE exons, intron-exon boundaries, and 588 bp of the 5' region in 5 patients negative for the C282Y mutation. We have detected a high frequency of the C282Y mutation (85.1%) in Spanish HH patients, indicating that this mutation is the most common defect associated with the disease in Spain. The screening of the HFE regions in our patients without the C282Y mutation has revealed the presence of five polymorphisms. However, no other pathological mutations have been found. Therefore, further efforts to characterize the unscreened part of the HFE gene or other loci should be taken to identify the potential genetic factors causing HH in the C282Y-negative patients.

Hyphomonas adhaerens sp. nov., Hyphomonas johnsonii sp. nov. and Hyphomonas rosenbergii sp. nov., marine budding and prosthecate bacteria

Three strains of prosthecate, budding bacteria, MHS-2T, MHS-3T and VP6T, were isolated from marine habitats including the open ocean (the pelagic zone), the offshore region (the neritic zone) and the hydrothermal vent region. A polyphasic approach including 16S rDNA sequencing, phenotypic analyses, serology, fatty acid analyses, membrane protein profiles and DNA-DNA hybridizations was used to place these strains in the genus Hyphomonas, a taxon of the alpha-Proteobacteria. The results of these analyses also showed that strains MHS-3T, MHS-2T and VP6T each represent a new species of Hyphomonas. The names Hyphomonas adhaerens (type strain MHS-3T, ATCC 43965T), Hyphomonas johnsonii (type strain MHS-2T, ATCC 43964T) and Hyphomonas rosenbergii (type strain VP6T, ATCC 43869T) are proposed for the new species. With these additions, Hyphomonas now contains eight species.

Gonadotrophin and testosterone suppression by 7alpha-methyl-19-nortestosterone acetate administered by subdermal implant to healthy men

The synthetic androgen 7alpha-methyl-19-nortestosterone (MENT) is a potent suppressor of gonadotrophin that has several advantages for long term administration to normal or hypoandrogenic men. The aim of this study was to examine MENT serum concentrations following subdermal insertion of MENT acetate (MENT Ac) implants and their effects on gonadotrophins, testosterone, dihydrotestosterone (DHT), sex hormone-binding globulin, prostate specific antigen and insulin-like growth factor-1 serum concentrations in normal men. A total of 45 healthy men were recruited at three clinics. Each subject received one, two or four implants for 28 days. Serum samples were obtained before insertion and on days 8, 15, 22, 29, 36 and 43 after implant insertion. The average daily dose delivered in vivo by one implant was approximately 500 microg. One, two or four MENT Ac implants produced dose dependent and sustained serum MENT concentrations for the entire duration of treatment of 0.7 +/- 0.1, 1.2 +/- 0.1 and 2.0 +/- 0.1 nmol/l respectively. This treatment induced a dose dependent decrease in gonadotrophin and androgen serum levels. Two and four implants induced maximal suppression that was maintained throughout treatment and was completely reversed after removal of the implants. The mean decreases were 93 +/- 1% for testosterone, 80 +/- 3% for DHT, 97 +/- 1% for luteinizing hormone and 95 +/- 1% for follicle stimulating hormone. No serious adverse reactions were reported by the volunteers and no consistent changes in clinical chemistry and haematology were found. These results indicate that MENT Ac implants are an efficient way of MENT administration and confirm the potent gonadotrophin and androgen suppressive effect of this drug.

Radiocesium accumulation in edible wild mushrooms from coniferous forests around the Nuclear Centre of Mexico

Cs-137 and K-40 have been determined in soil samples and in wild edible mushrooms from a forest ecosystem located at the Nuclear Centre of Mexico (NCM) and in several surrounding localities. The transfer factors for Cs-137 were studied in 21 mushroom species from 1993 to 1997. The Cs-137 and K-40 determinations were performed using a gamma spectrometer system of low level counting with a high purity germanium (HPGe) detector. The local mushroom species that were found to show higher Cs-137 transfer factors were Clavariadelphus truncatus, Cortinarius caerulescens, Gomphus floccosus and Lyophyllum decastes. The Cs-137 levels obtained at the NCM in some mushroom samples were slightly lower than those from surrounding localities indicating that the nuclear facility has not emitted Cs-137 to the atmosphere.

Gastric mucosal blood flow regulation in response to different stimuli

We compared changes in gastric mucosal blood flow (GMBF) and left gastric artery blood flow (LGABF) in response to pharmacological, physiological, and pathological stimuli. GMBF and LGABF were measured by the hydrogen gas clearance and perivascular ultrasonic transit time techniques, respectively, under baseline conditions and following intravenous infusion of vasopressin or pentagastrin, isovolemic hemodilution, or gastric perfusion with HCl-taurocholate. Blood flow changes following vasopressin or hemodilution were significantly larger in the left gastric artery than in the gastric mucosa. In contrast, the increment in blood flow associated with pentagastrin-stimulated acid secretion was significantly greater in the gastric mucosa than in the extramural artery. Barrier disruption with acid-taurocholate induced similar changes in both measurement sites. The gastric hyperemia induced by either mechanism was significantly attenuated by blockade of NO synthesis. These data demonstrate that although functional changes in GMBF are primarily supported by changes in blood flow at the extramural gastric arteries, the gastric mucosal microvasculature is also under the influence of independent local control mechanisms.

Constitutive NOS isoforms account for gastric mucosal NO overproduction in uremic rats

To study whether renal failure enhances gastric mucosal nitric oxide (NO) formation in the rat, we measured 1) in vivo NO concentration and 2) NO synthase (NOS) activity, content, and mRNA expression in gastric mucosal homogenates of uremic and sham-operated anesthetized rats. Gastric mucosal NO release was measured by an electrochemical technique. NOS content was analyzed by Western immunoblots, using specific monoclonal antibodies. Constitutive (Ca2+ dependent; cNOS) and inducible (Ca2+ independent; iNOS) NOS activities were assayed by following the conversion of L-[U-14C]arginine to [U-14C]citrulline. mRNA expression for the constitutive neuronal (ncNOS), endothelial (ecNOS), and iNOS isoforms was determined by reverse transcription-polymerase chain reaction. Under basal conditions, gastric mucosal NO concentration was significantly greater in uremic compared with control rats. This was accompanied by significantly greater gastric mucosal cNOS activity in uremic rats than in control rats, whereas no differences were observed in iNOS activity between both groups of animals. Moreover, total enzyme content and the levels of gastric mucosal mRNA expression for ncNOS, ecNOS, and iNOS showed no significant differences between uremic and sham-operated rats. These data confirm that, in uremic rats, enhanced Ca2+-dependent NOS activity is responsible for gastric mucosal NO overproduction and suggest that the main regulatory mechanism is not transcriptional but translational and/or posttranslational in nature.

Structure, function and immunochemistry of bacterial exopolysaccharides

There has been much written on bacterial exopolysaccharides (EPS) and their role in virulence. Less has been published regarding EPS in free living species. This review focuses on that subject, emphasizing their functions in the environment and the use of antibody probes to study them.

Gastrin mediates the increase in gastric cell growth in uremic rats

In a rat model of chronic renal failure, we recently reported that hypergastrinemia was associated with increased stomach weight and parietal cell and enterochromaffin-like (ECL) cell density. In this study, the role of gastrin in mediating trophic effects of uremia on the gastric mucosa was examined by chronic immunoneutralization of endogenous gastrin in the sub-total nephrectomy uremic rat model. Three weeks after surgery, the rats were uremic (azotemic and hypertensive). Uremic rats had a significant increase in corpus mucosal height (17%), parietal cell density (14%), ECL cell density (27%), and basal gastric mucosal blood flow (63%). These effects were specifically inhibited by chronic administration of gastrin-specific monoclonal antibody (5 mg ip every other day) in the 3-wk postoperative period. Uremic rats also had an increase in stomach weight (23%), corpus mucosal area (8%), arterial blood pressure, and serum creatinine and a decrease in body weight. Gastrin immunoneutralization did not alter these effects. The findings suggest that elevated levels of endogenous circulating gastrin in uremic rats mediate, in part, the trophic response observed in the gastric mucosa.

Gastric emptying of solids but not liquids is decreased in rats with chronic renal failure

Severe gastric complications occur in uremic patients, yet few studies have addressed the effect of chronic renal failure (RF) on gastric physiology. In the present study, we investigated: (1) the effect of RF on gastric emptying of liquids and solids in awake rats, (2) the motor function in the gastric corpus, and (3) the role of nitric oxide in any alterations in gastric motor function in uremic rats. RF was induced by partial kidney infarction. RF had no effect on gastric emptying of liquids but significantly inhibited gastric emptying of solids by 68%. N-Nitro-L-arginine, an inhibitor of nitric oxide (NO) synthesis, had no effect on the reduced gastric emptying of solids in RF rats. RF rats showed an altered pattern of gastric motility compared to sham-operated rats. These data suggest that RF induced an inhibition of gastric emptying of solids, but not liquids. However, NO does not seem to play a role in this inhibition.

Prostaglandin E2 enhances gastric defense mechanisms against acid injury in uremic rats

BACKGROUND/AIMS

Uremia increases gastric mucosal H+ permeability and acid back-diffusion-related injury in rats. The aim of this study was to examine the effect of the synthetic gastroprotective compound 16,16-dimethyl prostaglandin E2 (16,16-dm PGE2) on the gastric barrier to acid injury in uremic rats.

METHODS

Chronic renal failure was induced by subtotal nephrectomy. Acid back-diffusion injury was induced by superfusion with 15% ethanol in 0.15N HCl and was assessed by image analysis. Intracellular pH, initial surface cell acidification rate, and thickness of mucous gel layer were measured with in vivo microscopy. Gastric mucosal blood flow was measured in separate experiments by laser-Doppler flowmetry.

RESULTS

Pretreatment with 16,16-dm PGE2 attenuated H+ back-diffusion and prevented the production of gross lesions. 16,16-dm PGE2 increased gastric mucous gel thickness, decreased initial acidification rate, and maintained intracellular pH homeostasis during exposure to luminal acid. Gastric mucosal blood flow was not changed during superfusion with a neutral buffer but increased during acid exposure in rats treated with 16,16-dm PGE2.

CONCLUSIONS

16,16-dm PGE2 attenuated H+ back-diffusion injury in uremic rats. This effect was associated with blunting of the initial decrease of intracellular pH and enhanced surface cell intracellular pH homeostasis during acid exposure. These effects were associated with an increased mucous gel layer thickness and an acid-related increase in blood flow.

Uremia in the rat affects gastric cell growth and differentiation

The aim of this study was to determine if hypertrophy of different tissues seen in uremic rats included gastrointestinal hypertrophy and an increase in parietal cell mass that might explain the increased acid secretion we previously reported. Chronic renal failure was induced by subtotal nephrectomy. Despite a lower total body weight, uremic rats had a significantly greater stomach weight (33%), corpus area (13%), corpus mucosal height (19%), and parietal (32%) and enterochromaffin-like (ECL, 54%) cell density, but a 16% decrease in mucous neck cell region height. These findings suggest that uremia leads to gastric stem cell stimulation with differentiation favoring parietal and ECL cells over mucous cells. In addition, in uremic rats there was an increase in height of the duodenal mucosa, but not of the ileal or transverse colon mucosa. In conclusion, the present study shows that uremia in the rat promotes hypertrophy of the stomach with cell differentiation favoring parietal cells over mucus cells. The increase in parietal cell mass may explain the increased acid secretion in these rats.

Delayed gastric emptying induced by inhibitors of nitric oxide synthase in rats

The effect of the nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine methyl ester, on gastric emptying of a non-nutrient solution was investigated in conscious rats. NG-Monomethyl-L-arginine (10 mg/kg i.v.) and NG-nitro-L-arginine methyl ester (3 or 10 mg/kg i.v.) inhibited the 20-min rate of gastric emptying of liquids by 34%, 69% and 84% respectively, whereas the 0.3 mg/kg of NG-nitro-L-arginine methyl ester or 3 mg/kg of NG-monomethyl-L-arginine had no effect. The inhibitory effect of NG-nitro-L-arginine methyl ester (3 mg/kg) was prevented by L-arginine (300 mg/kg i.v.), but not by D-arginine (300 mg/kg i.v.). NG-Nitro-L-arginine methyl ester (0.3-10 mg/kg) induced a dose-related increase in mean blood pressure up to 161 +/- 10 mm Hg. Spontaneous hypertensive rats with a mean blood pressure of 180 +/- 5 mm Hg had a gastric emptying rate of 51.9 +/- 6.1%. These data indicate that NO synthase inhibitors given i.v. at doses that inhibit NO synthase, delay gastric emptying through mechanisms which are unrelated to changes in arterial blood pressure.

Uremia increases gastric mucosal permeability and acid back-diffusion injury in the rat

The possibility that chronic uremia renders the gastric mucosa more susceptible to acid injury was investigated. A rat model of chronic renal failure was induced by subtotal nephrectomy. [H+] back-diffusion across the mucosa, following intragastric perfusion of 0.15N HCl or 15% ethanol in 0.15N HCl, was significantly greater in uremic than in sham-operated rats. Gastric mucous gel thickness and transmural potential difference were significantly lower in rats with renal insufficiency. Furthermore, a significantly greater acidification rate of the surface epithelial cells was found in uremic rats than in sham-operated rats during superfusion with pH 1.7 buffer. Intragastric administration of acidified ethanol or aspirin solutions markedly increased gastric mucosal blood flow (68% and 89% respectively) in the sham-operated group producing mild injury, in contrast to uremic rats, where a lesser increase in mucosal blood flow (7% and 14% respectively) was associated with more pronounced mucosal injury. It was concluded that enhanced susceptibility to acid injury in uremia is due to a reduction of function of pre-epithelial, epithelial, and postepithelial elements of the gastric mucosal barrier.

Nitric oxide-mediated gastric hyperemia decreases ethanol-induced gastric mucosal injury in uremic rats

We investigated whether the recently described endothelium-derived nitric oxide-mediated gastric hyperemia in the uremic rat protects the gastric mucosa against ethanol injury. Uremia was induced by subtotal nephrectomy. Basal gastric mucosal blood flow, measured by a hydrogen gas clearance technique, was significantly higher in uremic than control rats. Continuous intragastric perfusion with 40% ethanol produced significantly less gross and histological lesions in uremic than in control rats. The administration of 3 mg/kg of NW-nitro-L-arginine methyl ester, a specific inhibitor of nitric oxide biosynthesis, decreased resting gastric mucosal blood flow to control levels in uremic rats, but had no effect on basal gastric blood flow in control rats. This pretreatment with the inhibitor of nitric oxide biosynthesis increased 40% ethanol-induced gastric mucosal lesions in uremic rats to the same level as that observed in control rats, but had no effect on lesions in control rats. In conclusion, this study suggests that in the uremic rat, gastric hyperemia, mediated by increased endothelium-derived nitric oxide, attenuates ethanol-induced gastric mucosal injury.