Diurnal changes in pathogenic and indicator virus concentrations in wastewater.

Wastewater-based epidemiology (WBE) has been commonly used for monitoring SARS-CoV-2 outbreaks. As sampling times and methods (i.e. grab vs composite) may vary, diurnal changes of viral concentrations in sewage should be better understood. In this study, we collected untreated wastewater samples hourly for 4 days at two wastewater treatment plants in Wales to establish diurnal patterns in virus concentrations and the physico-chemical properties of the water. Simultaneously, we also trialled three absorbent materials as passive samples as a simple and cost-efficient alternative for the collection of composite samples. Ninety-six percent of all liquid samples (n = 74) and 88% of the passive samplers (n = 59) were positive for SARS-CoV-2, whereas 87% and 97% of the liquid and passive samples were positive for the faecal indicator virus crAssphage, respectively. We found no significant daily variations in the concentration of the target viruses, ammonium and orthophosphate, and the pH and electrical conductivity levels were also stable. Weak positive correlations were found between some physico-chemical properties and viral concentrations. More variation was observed in samples taken from the influent stream as opposed to those taken from the influent tank. Of the absorbent materials trialled as passive samples, we found that tampons provided higher viral recoveries than electronegative filter paper and cotton gauze swabs. For all materials tested, viral recovery was dependent on the virus type. Our results indicate that grab samples may provide representative alternatives to 24-h composite samples if taken from the influent tank, hence reducing the costs of sampling for WBE programmes. Tampons are also viable alternatives for cost-efficient sampling; however, viral recovery should be optimised prior to use.

Effect of corticosteroids on the biomechanical strength of rat rotator cuff tendon.

BACKGROUND: The effect of corticosteroids on tendon properties is poorly understood, and current data are contradictory and diverse. The biomechanical effect of steroids on rotator cuff tendon has not been studied, to our knowledge. The current study was undertaken to characterize the biomechanical effects of corticosteroid exposure on both uninjured and injured rat rotator cuff tendon. METHODS: One hundred and twenty-three male Sprague-Dawley rats were randomly assigned to four groups: control (C), tendon injury (I), steroid exposure (S), and tendon injury plus steroid exposure (I+S). Unilateral tendon injuries consisting of a full-thickness defect across 50% of the total width of the infraspinatus tendon were created. Steroid treatment consisted of a single dose of methylprednisolone placed into the subacromial space. At one, three, and five weeks postoperatively, the shoulders were harvested and the infraspinatus tendon was subjected to biomechanical testing. Two specimens from each group were used for histological analysis. RESULTS: At one week, maximum load, maximum stress, and stiffness were all significantly decreased in Group S compared with the values in Group C. Mean maximum load decreased from 37.9 N in Group C to 27.5 N in Group S (p < 0.0005). Mean maximum stress decreased from 18.1 MPa in Group C to 13.6 MPa in Group S (p < 0.0005). Mean stiffness decreased from 26.3 N/mm in Group C to 17.8 N/mm in Group S (p < 0.0005). At one week, mean maximum stress in Group I+S (17.0 MPa) was significantly decreased compared with the value in Group I (19.5 MPa) (p < 0.0005). At both the three-week and the five-week time point, there were no significant differences between Group C and Group S or between Group I and Group I+S with regard to mean maximum load, maximum stress, or stiffness. Histological analysis showed fat cells and collagen attenuation in Groups S and I+S. These changes appeared to be transient. CONCLUSIONS: A single dose of corticosteroids significantly weakens both intact and injured rat rotator cuff tendons at one week. This effect is transient as the biomechanical properties of the steroid-exposed groups returned to control levels by three weeks.

Ring-testing and field-validation of a terrestrial model ecosystem (TME)--an instrument for testing potentially harmful substances: fate of the model chemical carbendazim.

The fate of the fungicide carbendazim (applied in the formulation Derosal) in soil was determined in Terrestrial Model Ecosystem (TME) tests and corresponding field-validation studies, which were performed in four different countries (United Kingdom, Germany, Portugal, and The Netherlands). The tests used different soil types, and lasted for 16 weeks. On three of the four sites, grassland soils were used while the fourth site had an arable soil. TMEs consisted of intact soil columns (diameter 17.5 cm; length 40 cm) and were taken from the site where the field study was performed. In the first series of TME tests, carbendazim was applied at four dosages ranging between 0.36 and 77.8 kg a.i./ha, while in the second series of TME tests and the field-validation studies six dosages between 0.36 and 87.5 kg a.i./ha were applied. DT50 values for the dissipation of carbendazim in the TME and field tests were in most cases not significantly affected by the dosage used and ranged between 3.1 and 13.9 weeks in the top 15 cm soil layers. Corresponding DT90 values ranged between 10.1 and 46.1 weeks. DT50 and DT90 values tended to be higher in the more acidic soils of Amsterdam and Flörsheim (pH-KCl 4.8-5.1 and 5.3-5.9, respectively) than in the less acidic soils of Bangor and Coimbra (pH-KCl 5.8-6.6 and 6.4-7.1, respectively). Fate of carbendazim in soil showed similar patterns in the two TME tests and the corresponding field-validation study performed at each site. The only exception was Flörsheim, where the compound was significantly more persistent in the field probably due to different climatic conditions. Carbendazim was not recovered from leachates produced in the TME tests, nor was the compound detected in soil layers deeper than 15 cm. This demonstrates that no significant leaching occurred. This study demonstrates the the TME tests were quite successful in predicting the fate of carbendazim under field conditions.

The management of perforated necrotizing enterocolitis - abstract

Fourteen patients with perforated, necrotizing enterocolitis (NEC) managed at the University Hospital of the West Indies are reviewed. Seven patients had peritoneal drains sited under local anaesthesia as a resuscitative measure in preparation for laparotomy. Six demised, five within 24 hours of siting drains and one soon after laparotomy. The single survivor after peritoneal drainage responded well enough not to require laparotomy. Four patients had immediate exploration, leading to death in one. Two patients had localized perforation, resulting in abscess formation. Both were drained but were complicated by intestinal stricture. Of these two patients, one survived. Perforated NEC was diagnosed at post-mortem in one patient. We conclude that a high index of suspicion is required for the early detection of NEC perforation. Peritoneal drains have limited application in this condition: only in low birth weight and in unstable, perforated neonates under 1,500 gm. Intestinal resection and stoma formation is the recommended operative approach but primary anastomosis is justified for fit, well-resuscitated neonates (AU)