Nitrogen patterns in subsurface waters of the Yzeron stream: effect of combined sewer overflows and subsurface-surface water mixing.

Urbanization subjects streams to increased nitrogen loads. Therefore studying nitrogen forms at the interface between urban stream and groundwater is important for water resource management. In this study we report results on water δ(18)O and nitrogen forms in subsurface waters of a stream (Yzeron, France). The sites studied were located upstream and downstream of combined sewer overflows (CSO) in a rural area and a periurban area, respectively. Water δ(18)O allowed us to follow the mixing of subsurface water with surface water. Dissolved organic nitrogen and organic carbon of fine sediment increased by 20-30% between rural and periurban subsurface waters in the cold season, under high flow. The highest nitrate levels were observed in rural subsurface waters in the cold season. The lowest nitrate levels were found in periurban subsurface waters in the warm season, under low flow. They corresponded to slow exchange of subsurface waters with channel water. Thus reduced exchange between surface and subsurface waters and organic-matter-rich input seemed to favor nitrate reduction in the downstream, periurban, subsurface waters impacted by CSO.

Bioassessment of wet-weather pollution impacts on fine sediments in urban waters by benthic indices and the sediment quality triad.

Benthic invertebrate assessments can be used to gauge the impact of urban wet-weather flows in receiving waters. Experiences from Cemagref in France have shown that standardized benthic indices (e.g. Oligochaete Index of Sediment Bioindication - IOBS) can be used to reliably determine the ecological status of urban streams and can be incorporated into the new European Water Framework Directive. The Canadian studies on streams and stormwater ponds using chemical analyses, benthic toxicity testing and benthic invertebrate community structure (i.e. the sediment quality triad) comparisons have shown that toxicity was more likely to occur in ponds at sites with higher concentrations of heavy metals and heavier polycyclic aromatic hydrocarbons, and at greater water depths, where fine sediments from urban runoff accumulated. A more comprehensive evaluation of wet-weather flow impacts could be obtained by combining approaches from both countries.

Dynamics of toxicity within different compartments of a peri-urban river subject to combined sewer overflow discharges.

Combined Sewer Overflows (CSO) in small peri-urban streams and rivers are potentially toxic for their biocenosis. Improving the management of CSO discharges requires better knowledge of their dynamics and toxicity. In view to characterizing this toxicity, we sampled the different compartments (benthic and hyporheic zone) of a peri-urban stream located near the city of Lyon in France. The samples were taken at different distances from a CSO and at three period characteristic of different hydrological conditions. Their toxic effects were assessed by bioassays on the dissolved fraction (D. magna, V. fisheri and B. calyciflorus bioassays) and on the particle fraction (V. fisheri and H. incongruens bioassays). The results highlighted significant toxicity of the particulate fraction for the benthic and hyporheic samples, in particular downstream of the CSO, but with high spatio-temporal variability. This variability can first be attributed to the variability of CSO discharge sampling as a function of season and rainfall, and the dynamics of polluted particles (trapping of transported particles in infiltration zones, mobilization during floods). These parameters play a fundamental role in the distribution of pollutants according to the geomorphology of stream facies. Regarding dissolved pollutants, the chemical exchanges taking place at the "water-sediment" interface trigger the transfer of pollutants from one phase to another, after which the dispersion of these pollutants is governed by hydraulic flows. Finally, critical zones and periods are identified for the peri-urban river toxicity studied: benthic sediments under mean flow downstream; hyporheic sediments after a storm event downstream, close to the CSO. Recommendations are made on the basis of the knowledge obtained to optimize the management of these discharges.

Effects of erythromycin on hepatic drug-metabolizing enzymes in humans.

In rats, erythromycin has been shown to induce microsomal enzymes and to promote its own transformation into a metabolite which forms an inactive complex with reduced cytochrome P-450. To determine whether similar effects also occur in humans, we studied hepatic microsomal enzymes from six untreated patients and six patients treated with erythromycin propionate, 2 g per os daily for 7 days. In the treated patients, NADPH-cytochrome c reductase activity was increased; the total cytochrome P-450 concn was also increased but part of the total cytochrome P-450 was complexed by an erythromycin metabolite. The concn of uncomplexed (active) cytochrome P-450 was not significantly modified and the activity of hexobarbital hydroxylase remained unchanged. We also measured the clearance of antipyrine in six other patients; this clearance was not significantly decreased when measured again on the seventh day of the erythromycin propionate treatment. We conclude that the administration of erythromycin propionate induces microsomal enzymes and results in the formation of an inactive cytochrome P-450-metabolite complex in humans. However, the concn of uncomplexed (active) cytochrome P-450 and tests for in vitro and in vivo drug metabolism were not significantly modified.

Formation of an inactive cytochrome P-450 Fe(II)-metabolite complex after administration of troleandomycin in humans.

In rats, it has been shown that troleandomycin induces its own transformation into a metabolite forming an inactive complex with reduced cytochrome P-450. To determine whether similar effects occur in humans, we studied hepatic microsomes from 6 untreated patients and 6 patients treated with troleandomycin, 2 g per os daily for 7 days. In the treated patients, NADPH-cytochrome c reductase activity was increased by 48%; total cytochrome P-450 concentration was also increased, but 33% of total cytochrome P-450 was complexed by a troleandomycin metabolite. The cytochrome P-450 Fe(II)-metabolite complex exhibited properties identical to those of the inactive complex formed in rats: it exhibited a Soret peak at 456 nm, was unable to bind CO, and was destroyed by addition of 50 microM potassium ferricyanide. We also measured the clearance of antipyrine in 6 other subjects. This clearance was decreased by 45% when measured again on te seventh day of the troleandomycin treatment. We conclude that repeated administration of troleandomycin induces microsomal enzymes, produces an inactive cytochrome P-450 Fe(II)-metabolite complex, and decreases the clearance of antipyrine in humans.

Gastrointestinal Richter's syndrome.

The development of a diffuse large cell lymphoma of the stomach in a patient who had chronic lymphocytic leukemia is reported. Richter's syndrome localized to the gut has not been described previously. Morphologic and immunologic studies suggest that the diffuse large cell lymphoma arose from the same clonal proliferation, IgG lambda, as the initially detected serum monoclonal protein associated with the chronic lymphocytic leukemia.

[Diagnosis and therapy of LASIK-induced neurotrophic epitheliopathy]. / Diagnostik und Therapie der LASIK-induzierten neurotrophen Epitheliopathie.

Laser in situ keratomileusis (LASIK) has emerged as the standard surgical procedure for the correction of refractive errors and in the last years a lot of experience has been gained. Consequently, the amount of intraoperative, early and late postoperative complications have significantly decreased. Keratitis punctata superficialis and dry eye symptoms are the most frequent postoperative complications. A decreased corneal sensitivity attributable to the cutting of the corneal sensory nerves has been described after LASIK. In addition pathological tear secretion tests and typical dry eye symptoms have been reported. Until know it has not been completely evaluated, if these symptoms are a combination of the dry eye disease and LASIK-induced symptoms or if they are due to an independent LASIK complication, the so-called LASIK-induced neurotrophic epitheliopathy. Independently of the incompletely understood etiology, much care and a sufficient therapy with artificial tears should be applied to such patients. To increase the comfort of LASIK, adequate intra- and postoperative treatment is necessary to enhance the patient satisfaction.

[The relationship between retrobulbar blood flow velocity and glaucoma damage. An intraindividual comparison]. / Verhältnis zwischen retrobulbären Blutflussgeschwindigkeiten und glaukomatösem Schaden. Ein intraindividueller Vergleich.

BACKGROUND: Glaucomatous optic nerve damage is thought to be influenced by ocular perfusion. The aim was to investigate if a difference in visual field and Heidelberg retinal tomography (HRT) between two eyes of an individual glaucoma patient is reflected in different blood flow velocities in retrobulbar vessels. METHODS: Data from 53 patients including 26 normal tension glaucoma patients (NTG) and 27 high tension glaucoma patients (HTG) were evaluated retrospectively. In 38 patients asymmetric glaucomatous damage (AGD) could be demonstrated by both structural (HRT) and functional measures (static or Goldmann perimetry). In 15 patients there was symmetric glaucomatous damage (SGD). To discriminate between AGD and SGD we used a score for HRT and visual field. Color Doppler imaging (CDI) was performed with a Siemens Quantum 2000. RESULTS: No significant differences were found when comparing group means of intraindividual deviation of CDI in patients with AGD vs. SGD. Overall analysis of CDI values in NTG vs. HTG eyes also showed no significant differences. Nevertheless we measured decreased blood flow velocities for NTG compared to HTG eyes especially in short posterior ciliary arteries, peak systolic and end diastolic velocities. CONCLUSIONS: A simple correlation between retrobulbar blood flow velocities and glaucomatous damage could not be found. However, color Doppler images can give important additional information in the diagnosis of glaucoma, especially normal tension glaucoma.

Reoperation after Heller's operation for achalasia and other motility disorders of the esophagus: a study of eighty-one reoperations.

Most failures or pseudo-failures of Heller's operation are due to an imperfect surgical technique. The procedure should include the entire muscular layer, extend as far upwards as possible and at least two to three cm downwards onto the stomach. Furthermore, it should be associated with an anti-reflux procedure. Eighty-one operations were performed in 70 patients who had previously undergone Heller's operation. Of the 42 patients presenting with recurrent achalasia, 21 had an insufficient Heller procedure upwards, 10 downwards and 11 in depth. Twenty-three patients had peptic esophagitis and three had periesophageal sclerosis. The management of these 70 reoperated patients included 36 iterative esophageal myotomies, 32 resections, four total duodenal diversions and two hiatal reconstructions. Repeated cardiomyotomies gave excellent results in 75% of cases and esophagogastric resection in 79%.

[Primary lymphomas of the digestive tract. Therapeutic results of a series of 35 cases]. / Lymphomes primitifs du tube digestif. Résultats thérapeutiques dans une série de 35 cas.

We report the results of a diagnosis and treatment scheme used in 35 patients with primary gastrointestinal lymphoma studied between 1972 and 1982. There were 17 lymphomas of the stomach, 13 of the small bowel, 6 of the colon and/or the rectum. According to the Kiel classification and/or the International Working Formulation, 10 were "good risk" lymphomas, 25 were "bad risk" lymphomas. According to the Musshoff modified Ann Arbor staging classification, 16 were localized lymphomas (stage IE and II1E), 19 were disseminated lymphomas (stages II2E, IIIE or IV). The treatment scheme included laparotomy for staging and resection, total abdominal irradiation (until 1977), and polychemotherapy with or without adriamycin depending on histologic grade. The median survival was greater than the median follow-up with a survival plateau at 0.53 after 47 months. Amongst the prognostic factors studied, the digestive initial localization had no prognostic significance; on the other hand, survival depended on abdominal extension, histologic grade according to the classifications used for lymph-nodes lymphomas, and resection possibilities, and especially on achievement of complete remission. These good results emphasize the importance of combining surgical resection with chemotherapy and early assessment of the treatment in order to rapidly obtain complete remission, the way of achieving prolonged survival.

[Surgical treatment of failures or recurrences after Heller cardiomyotomy (author's transl)]. / Les réinterventions après intervention de Heller pour achalasie et autres dysfonctionnements moteurs de l'oesophage.

A Heller cardiomyotomy has been realized in 406 cases of achalasia. The indications for operation are defined. Surgery must be preferred to dilatation: the results are favorable in 96% of cases. The failures or so-called failures are detailed. In failures or recurrences due to an insufficient cardiomyotomy, a new myotomy is indicated. Gastro-esophageal reflux is frequently an indication for oesogastric resection. Failures have been observed in 70 cases. The insufficient initial myotomy was completed in 36 cases. The etiology of postmyotomy sclerosis (15 perioesophageal, 3 interstitial) is discussed. Severe peptic oesophagitis, observed in 15 cases, stresses the importance of restoring the anti-reflux mechanism, rather than using a thoracic approach with the risk of a myotomy too limited towards the stomach. Other causes of failures (atypical mega-oesophagus, limited peptic stenosis) are due to an erroneous interpretation of preoperative X-rays, endoscopy and manometric data: in such cases, the original treatment should have been adapted to the lesion. Finally, 8 postoperative oesophageal asystolias and 4 cancers stress the importance of an early myotomy, correctly realized through an abdominal approach.