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Biomedical subjects

R Colin

Publications and source records attributed to R Colin.

At least 19 recordsLinked to original sources
PubMed2002

UV Fourier transform measurements of tropospheric O3, NO2, SO2, benzene, and toluene.

Using the differential optical absorption spectroscopy (DOAS) technique and a Fourier transform spectrometer, NO2, SO2, O3, benzene. and toluene were measured during three measurement campaigns held in Brussels in 1995, 1996, and 1997. The O3 concentrations could be explained as the results of the local photochemistry and the dynamical properties of the mixing layer. NO2 concentrations were anti-correlated to the O3 concentrations, as expected. SO2 also showed a pronounced dependence on car traffic. Average benzene and toluene concentrations were, respectively 1.7 ppb and between 4.4 and 6.6 pbb, but high values of toluene up to 98.8 ppb were observed. SO2 concentrations and to a lesser extent, those of NO2 and 03, were dependent on the wind direction. Ozone in Brussels has been found to be influenced by the meteorological conditions prevailing in central Europe. Comparisons with other measurements have shown that 03 and SO2 data are in general in good agreement, but our NO2 concentrations seem to be generally higher.

Air Pollutants↗
PubMed2002

Duodenal ulcer healing with 1-week eradication triple therapy followed, or not, by anti-secretory treatment: a multicentre double-blind placebo-controlled trial.

BACKGROUND: In the management of Helicobacter pylori induced duodenal ulcer, it is still controversial whether anti-secretory treatment needs to be continued following a 1-week course of eradication therapy. METHODS: 150 patients with H. pylori active duodenal ulcer (diameter > or = 5 mm) were included. After a 1-week eradication treatment combining omeprazole 20 mg b.d., amoxicillin 1000 mg b.d. and clarithromycin 500 mg b.d. (OAC), patients were randomized to omeprazole 20 mg or placebo for 3 additional weeks. The primary variable was ulcer healing assessed at 4 weeks. Eradication was verified 4 weeks after cessation of study drugs by 13C-urea breath test. Intention-to-treat analysis (ITT) included 131 patients with positive histopathology at inclusion. RESULTS: Healing rates were not statistically different, at 89% and 87%, respectively, in the OAC-omeprazole and OAC-placebo groups (95% CI: -8.7; 13.7). Numerically, healing rates in patients with successful eradication was higher [94/104 (90%)] than in patients with failed eradication [21/27 (78%)]. However, the difference was not statistically significant (P < 0.1). CONCLUSIONS: One-week OAC eradication triple therapy achieves excellent healing rates in patients with uncomplicated duodenal ulcer disease. Although the confidence interval of the difference in healing suggests little or no benefit of continued omeprazole treatment after 1 week, larger studies are needed to address this issue definitively.

Administration, Oral↗
PubMed2001

There are some benefits for eradicating Helicobacter pylori in patients with non-ulcer dyspepsia.

BACKGROUND: The relationship between Helicobacter pylori infection and non-ulcer dyspepsia is not established. AIM: To determine whether eradication of H. pylori might be of benefit in non-ulcer dyspepsia patients. METHODS: We randomly assigned 129 H. pylori infected patients with severe epigastric pain, without gastro-oesophageal reflux symptoms, to receive twice daily treatment with 300 mg of ranitidine, 1000 mg of amoxicillin, and 500 mg of clarithromycin for 7 days and 124 such patients to receive identical-appearing placebos. RESULTS: Treatment was successful (decrease of symptoms at 12 months) in 62% of patients in the active-treatment group and in 60% of the placebo group (N.S.). At 12 months, the rate of eradication of H. pylori was 69% in the active-treatment group and 18% in the placebo group (P < 0.001). Complete relief of symptoms occurred significantly more frequently in patients on the active treatment (43%) than in placebo-treated patients (31%, P=0.048). Within the active-treatment group, therapeutic success was significantly more frequent in the non-infected patients (84% vs. 64%, P=0.04). CONCLUSIONS: Although eradicating H. pylori is not likely to relieve symptoms in the majority of patients with non-ulcer dyspepsia, a small proportion of H. pylori-infected patients may benefit from eradication treatment.

Adolescent↗
PubMed2001

Chronic hepatitis C with normal or abnormal aminotransferase levels: is it the same entity?

OBJECTIVE: The features of hepatitis C virus (HCV) infection with persistently normal serum alanine aminotransferase (ALT) activity levels are not well defined. This study evaluated the characteristics of HCV infection according to the presence or absence of elevated ALT. METHODS: Demographic data, liver histology and HCV genotype were studied in a group of 80 HCV-RNA-positive subjects with persistently normal ALT (PNALT) (group 1), and compared with a second group of 455 HCV-RNA-positive patients with elevated ALT (group 2). The annual progression of liver fibrosis was also calculated. RESULTS: A higher proportion of women was found in group 1:64% vs 42% in group 2 (P< 0.0002). The HCV genotype 1 was less frequent in group 1:49% vs 60% in group 2 and genotype 2 was more frequent: 16% in group 1 vs 4% in group 2 (P< 0.002). Cirrhosis was less frequent in group 1 (4% vs 13% in group 2 (P< 0.0001)). Normal liver was more frequent in group 1:9% vs 1% in group 2 (P< 0.0001). The Knodell score was significantly different between the two groups: 3.2 +/- 0.27 vs 7.15 +/- 0.22 (P< 0.0001). The progression of liver fibrosis was lower in group 1: 0.053 +/- 0.14 units/year vs 0.13 +/- 0.24 in group 2 (P < 0.007). CONCLUSION: HCV infection with PNALT is associated with less severe histological liver disease and a lower fibrosis progression rate. This suggests that the natural history of HCV infection in these patients is different from that in patients with abnormal ALT.

Adult↗
PubMed2001

Low levels of gastric mucosal glutathione during upper gastric bleeding associated with the use of nonsteroidal anti-inflammatory drugs.

OBJECTIVES: To investigate the glutathione concentrations in gastric mucosa from patients with acute gastric bleeding related to nonsteroidal anti-inflammatory drugs (NSAIDs), and to test the influence of nutritional status on mucosal glutathione. Glutathione protects the gastrointestinal mucosa against reactive oxygen species, and glutathione content in various tissues may be depleted during malnutrition. METHODS: Endoscopic biopsies were obtained from 39 patients. Eighteen of these (9 well-nourished, 9 malnourished) presented with gastric bleeding ulcers related to NSAIDs. Twenty-one other patients (12 well-nourished, 9 malnourished) underwent normal routine diagnostic endoscopy and served as controls. Malnutrition was defined as a loss of over 10% of normal body weight and/or plasma albumin levels below 30 g/l. Gastric biopsies were taken from the fundus and antrum (controls) and from the region of the ulcer (patients with acute bleeding) and frozen quickly until glutathione analysis by high-performance liquid chromatography (HPLC) coulometric detection. Results were expressed as nmol/mg wet tissue. RESULTS: Gastric mucosal glutathione levels were significantly (P < 0.05) lower in both the antrum (0.81 +/- 0.34 v. 1.41 +/- 0.88 nmol/mg tissue) and the fundus (1.04 +/- 0.54 v. 1.43 +/- 0.92 nmol/mg tissue, P < 0.05) in malnourished than in well-nourished control patients. Glutathione mucosal concentrations were decreased significantly in patients with NSAID-induced gastric bleeding compared with control patients (0.38 +/- 0.36 v. 1.12 +/- 0.56 nmol/mg tissue, P < 0.001), and the lowest glutathione levels were observed in malnourished patients (0.28 +/- 0.20 v. 0.48 +/- 0.15 nmol/mg tissue in well-nourished patients, not significant). CONCLUSION: Malnutrition is associated with low levels of gastric glutathione. This may contribute to the severity and the onset of haemorrhage in NSAID-induced gastric ulcers.

Acute Disease↗
PubMed2001

[Upper gastrointestinal bleeding in patients treated by low-dose aspirin].

AIM OF THE STUDY: To estimate the number of people treated by low-dose aspirin (<330 mg daily) in France and to evaluate the risk of upper gastrointestinal bleeding associated with low-dose aspirin treatment. SUBJECTS AND METHODS: One thousand six hundred and two patients with upper gastrointestinal bleeding were included between January and June 1996 in 4 French areas. Data about patients characteristics, drugs recently used, and bleeding lesions were prospectively collected. Five hundred seventy five cases were matched for sex, age and area with control people without previous upper gastrointestinal bleeding. Low-dose aspirin intake in the population was estimated from the control group. Aspirin intake in the previous 7 days in cases and in controls was compared by logistic regression, adjusted for other gastrotoxic drugs intake. RESULTS: Low-dose aspirin is taken by about 1.2 millions adults in France. In 1 602 patients, gastrointestinal bleeding was related to a peptic ulcer in 34%. Aspirin was associated with higher risk of upper gastrointestinal bleeding: OR=1.68 (1.03-2.74) with low-dose, and OR 1.42 (0.91-2.21) with higher doses. CONCLUSION: About 2.8% of the population is exposed to low-dose aspirin in France. This treatment seems to be associated with a high risk of upper gastrointestinal bleeding.

Adult↗
PubMed2000

[Gastroduodenal ulcer associated with Helicobacter pylori].

Helicobacter pylori is associated with chronic peptic ulcer disease. The high prevalence of H. pylori infection tends to decrease in Western countries suggesting that the incidence of gastroduodenal ulcers not related to antiinflammatory drugs will fall. Abundant data support the leading role of H. pylori in peptic disease through dysregulation of acid production, induction of gastric metaplasia, and development of chronic gastritis. Endoscopy is the key to diagnosis, allowing direct assessment of H. pylori infection. H. pylori eradication is the major aim of peptic ulcer treatment, dramatically improving the recurrence of ulcers, although its efficiency should be controlled in various clinical situations.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Fourier Transform Spectroscopy of the O(2) Herzberg Bands.

From absorption spectra obtained at high resolution by coupling a Fourier transform spectrometer to a long-path multiple reflection cell [A. Jenouvrier, M.-F. Mérienne, B. Coquart, M. Carleer, S. Fally, A. C. Vandaele, C. Hermans, and R. Colin, J. Mol. Spectrosc. 198, 136-162 (1999)] the intensities of the O(2) Herzberg bands (A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), A'( 3)Delta(u)-X(3)Sigma(-)(g)) have been studied at ambient temperature. The integrated cross section values are given for the lines of the (v'-0) bands in the A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), and A'( 3)Delta(u)-X(3)Sigma(-)(g) transitions with v' = 0-11, v' = 2-19, and v' = 2-12, respectively. The band oscillator strengths have been deduced and transition moments have been calculated. The total absorption values in the region of the Herzberg bands together with the photoabsorption values determined previously above the dissociation limit can be modeled by a single curve, in agreement with the continuity relationship of the cross sections through the dissociation limit. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Fourier Transform Spectroscopy of the O(2) Herzberg Bands. III. Absorption Cross Sections of the Collision-Induced Bands and of the Herzberg Continuum.

Absorption spectra of molecular oxygen were measured in the laboratory under temperature and pressure conditions prevailing in the Earth's atmosphere. Spectra of pure O(2), O(2) + N(2), and O(2) + Ar were recorded in the 41 700 to 33 000 cm(-1) region (240-300 nm) at a maximal optical path difference of 0.45 cm using a Fourier transform spectrometer and a multiple reflection gas cell. The different components of the spectra, namely the discrete bands of the three Herzberg systems, the Herzberg continuum, and the collision-induced diffuse Wulf bands, were separated. The contribution of the Herzberg bands was first subtracted using the line parameters determined previously [A. Jenouvrier, M.-F. Mérienne, B. Coquart, M. Carleer, S. Fally, A. C. Vandaele, C. Hermans, and R. Colin, J. Mol. Spectrosc. 198, 136-162 (1999)] from high-resolution data. Spectra recorded at various pressures then made it possible to determine by linear regression the intensity of the Wulf bands and the Herzberg continuum. The characteristics of the Wulf bands have been investigated in details: vibrational analysis, pressure effect, foreign gas effect, and a simulated spectrum are reported. The Herzberg continuum cross section is determined below the dissociation limit. A comparison with literature data is given. The new O(2) absorption cross sections and O(2)-O(2) collision-induced absorption cross sections are useful in connection with atmospheric measurements of ozone and other trace gases in the UV spectral region. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

[Digestive complications of aspirin].

INTRODUCTION: This review focuses on aspirin-related gastrointestinal side-effects and the mechanism by which aspirin causes gastrointestinal damage. CURRENT KNOWLEDGE AND KEY POINTS: Aspirin causes direct gastric damage by topical irritant effects and indirect damage via systemic inhibition of cyclooxygenase synthesis and microcirculation injury. The question of a possible synergistic relation between the presence of Helicobacter pylori infection and aspirin use on gastric damage is not resolved. The pathogenesis of small intestinal and colonic damage is less well understood; an increase in intestinal permeability and free radical synthesis are suggested. Gastric damage predominates. Gastroduodenal lesions from aspirin have been documented in endoscopy studies. The lesions occur rapidly, even for low-dose aspirin. The association of aspirin consumption with upper gastrointestinal bleeding has been well established. The main risk factors are advanced age, concomitant use of nonsteroidal antiinflammatory drugs and history of ulcer. Low-dose aspirin are associated with increased risk of gastrointestinal bleeding and this risk is dose-dependant. Chronic aspirin consumption can cause iron deficiency anaemia. Uncomplicated gastric ulcer (but not uncomplicated duodenal ulcer) is associated with aspirin use, with relative risk 3. Other upper gastrointestinal complications have been reported: stenosis and perforation. Aspirin can also damage other areas of the gastrointestinal tract. Oesophageal injuries (oesophagitis and stricture) have been reported. Aspirin is associated with variceal bleeding episodes in patients with cirrhosis. The adverse effects of aspirin on the small bowel are perforation, bleeding, increasing permeability. The adverse effects of aspirin on the large intestine are perforation, bleeding, collagenous colitis and anorectal stenosis with suppositories containing aspirin. Direct clinical data regarding prophylaxis with co-administration of a protective drug are not yet available for aspirin. FUTURE PROSPECTS AND PROJECTS: Patients should be made aware of adverse gastrointestinal effects due to aspirin. Further studies regarding prophylactic therapy of low-dose aspirin induced gastroduodenal lesions, which identify a subset of patients who may be at higher risk than the low-dose aspirin population as a whole, are warranted.

Aged↗
PubMed2000

[Evaluation of spontaneous peri-transfusional screening for HVC and HIV at the Rouen University Hospital Center].

INTRODUCTION: Since October 1996, French hospitals have been instructed to introduce screening for hepatitis C virus (HCV) and human immunodeficiency virus (HIV) in all patients before and 3 months after each blood transfusion. The aim of this study was to assess the degree to which this recommendation had been taken into account in a university hospital via a pre- and post transfusion screening comparison. PATIENTS AND METHODS: A retrospective study on the use or non-use of screening tests for HCV and HIV was carried out in 2 groups of 150 randomly selected patients who had received blood transfusions in 1996 and in 1998. RESULTS: The coverage by pre-transfusion screening tests for HCV and HIV varied from 23% in 1996 to 20% in 1998 (not significant). The post-transfusion screening tests were performed by the hospital in 6% of the cases in 1996 and in 3% of the cases in 1998 involving blood transfusion. CONCLUSION: This study suggests that in the majority of patients, screening (particularly post-transfusion screening) for HCV and HIV was not carried out, and that over the 2-year period considered no noticeable improvement was observed. However, these results only concerned one hospital in which no specific screening program had been introduced. It is therefore possible that these findings are not representative of the situation in other hospitals; further studies would be useful in this regard.

Adult↗
PubMed2000

Epidemiology and course of acute upper gastro-intestinal haemorrhage in four French geographical areas.

OBJECTIVE: To compare incidence rates and epidemiological characteristics of acute upper gastrointestinal haemorrhage (AUGIH) in France with those of other European studies. DESIGN: Population-based multi-centre prospective survey. SETTING: 29 public hospitals and 96 private specialists in gastroenterology in four administrative areas in France during 1996. SUBJECTS: A total of 2133 AUGIH patients 18 years and over were included in the six-month study. OUTCOME MEASURES: Incidence and mortality. RESULTS: The overall incidence in France was 143 cases per 100000 persons per year, classified as out-patients (16%), emergency admissions (59%) and in-patients (25%). The incidence rates increased with age except for in-patients, and were higher in males. Peptic ulcer (36.6%), varices (13.7%) and erosive disease (12.3%) were the most frequent diagnoses. In 677 patients (31.7%), aspirin, antiinflammatory drugs or corticosteroids were taken on the 7 days before bleeding. The overall mortality (out-patients excluded) was 14.3% (10.7% for emergency patients and 23% for in-patients). Mortality was associated with comorbidities (especially malignancies, cirrhosis, asthma or respiratory deficiency), was lower in emergency patients using non-steroid anti-inflammatory drugs, and higher in in-patients using corticosteroids. CONCLUSIONS: In France, patients with AUGIH are frequently managed as out-patients. Gastrotoxic drug use is frequently associated with AUGIH and constitutes a strategic opportunity for preventive treatment. Discrepancies between countries are not clearly explained either by demographic factors or by drug use, but this may be related to the emphasis on AUGIH in in-patients.

Acute Disease↗
PubMed2000

His-Purkinje system reentry as a proarrhythmic effect of flecainide.

We report a case of tachycardia due to reentry within the His-Purkinje system (HPS) occurring after introduction of flecainide. The patient presented with a mild mitral regurgitation and normal left ventricular function. He had incomplete left bundle branch block with left-axis deviation. At the electrophysiology study, a prolonged HV interval was observed at baseline, and the tachycardia could be reproduced after ajmaline infusion. Six months after interruption of flecainide, the patient remains free of arrhythmia recurrence. The authors emphasize that proarrhythmic effects of flecainide may include reentry within the HPS in patients with underlying HPS disease.

Administration, Oral↗
PubMed2000

Low sensitivity of invasive tests for the detection of Helicobacter pylori infection in patients with bleeding ulcer.

BACKGROUND: A high false negative rate for antral infection with Helicobacter pylori when assessed by rapid urease test has recently been reported in patients with bleeding ulcer. This result could partly explain the differing prevalence of H. pylori infection in bleeding and non-bleeding ulcers. AIMS: To evaluate the accuracy of a rapid urease test (UT), histology and culture for detection of H. pylori in antral biopsies from acute bleeding peptic ulcer patients using a serological test as reference. PATIENTS AND METHODS: All consecutive patients with active bleeding gastric or duodenal ulcer at endoscopic examination admitted in six university hospitals in France were considered for inclusion. Five antral biopsies were taken during the diagnostic endoscopy for UT, culture and histology. A blood sample was taken for H. pylori serology. RESULTS: One hundred and eighty one patients were included and 129 (71%) had a positive serology. The sensitivity of UT, histology and culture for detection of H. pylori infection were 41%, 33% and 34%, respectively. The sensitivity and specificity of the combination of the three invasive tests were 48.8% (95% CI: 40.2-57.4) and 90.6% (95% CI: 82. 6-99) respectively. In the 52 serologically negative patients, only 5 had at least one invasive positive test. The sensitivity of the invasive tests decreased significantly with age but was not influenced by NSAIDs intake. Of 80 patients with a positive serological test and negative histological evaluation for H. pylori, chronic antral inflammation was found in 70 patients (87%). In 46 patients with both negative serological test and H. pylori negative test according to histology, only 13 (28%) had chronic antral inflammation. CONCLUSIONS: The sensitivity of invasive tests for detection of H. pylori is low during acute ulcer bleeding, and they should be used with caution in this condition. A serological test is recommended to identify patients with H. pylori infection in spite of negative invasive tests.

Aged↗
PubMed2000

[Management of upper digestive hemorrhage occurring in the community: patterns of patient care in 4 French administrative areas].

AIMS: To describe patterns of health care management in patients with upper gastrointestinal hemorrhage and to identify factors linked to the different patterns. PATIENTS AND METHODS: We conducted a prospective study of patients over 18 with upper gastrointestinal hemorrhage (inpatients excluded) among all public hospitals and private practice gastroenterologists in 4 French administrative areas (3 in Northern France and one in the South West). RESULTS: One thousand six hundred and two patients were included over a six-month period (1996). An endoscopic procedure was performed in 1532 patients in public (70%) or private (20.5%) hospitals, or at private office (9.5%). Hospitalization was necessary in 78.8% of the patients in university, non university public or private hospitals (38.9, 45.5 and 15.6%, respectively) with a median duration of 6.5 days. Admission was associated to old age, short delay between hemorrhage and endoscopic procedure, previous gastrointestinal bleeding, cirrhosis or cancer, bleeding from peptic ulcer or esogastric varices. Endoscopic hemostasis was performed in 21.4% of the patients, more often in university and no university public hospitals. Surgery was necessary in 4% of the patients. Death rate was 10.7%. Important geographical variations were observed concerning referral patterns. Patients' characteristics did not differ between the 4 areas. On the other hand, health care supply provided in the management of upper gastrointestinal hemorrhage was different in the four French geographical areas. CONCLUSION: a) An initial endoscopic procedure is nearly always performed in patients with an upper gastrointestinal hemorrhage in France; in 1 patient out of 10, endoscopy was performed in a private gastroenterologist office; b) hospital admission was strongly related to epidemiological and clinical criteria of severity; c) the geographical variations observed in referral patterns depend in part on health care supply; d) upper gastrointestinal haemorrhage status could be used as an indicator of the quality of health care organizations.

Adult↗
PubMed1999

Fourier Transform Spectroscopy of the O(2) Herzberg Bands.

The absorption spectra of the O(2) Herzberg band systems (A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), and A' (3)Delta(u)-X(3)Sigma(-)(g)) lying in the wavelength region 240-300 nm were reinvestigated. The coupling of a long absorption cell and a high-resolution Fourier transform spectrometer has allowed the observation of numerous weak lines which were not reported previously. From the rotational analysis of the line positions, determined with an accuracy of 0.005 cm(-1), the molecular constants of the A(3)Sigma(+)(u), v = 0-12, c(1)Sigma(-)(u), v = 2-19, and A' (3)Delta(u), v = 2-12 levels are improved significantly. The interaction between the A and c states is described quantitatively. A new interpretation of the perturbations observed in the energy region close to the dissociation limit is given which involves a weakly bound (3)Pi(u) state as the most probable perturbing state. Copyright 1999 Academic Press.

Journal Article↗