Bacterial community structure and response to nitrogen amendments in Lake Shenandoah (VA, USA).

Microbial processes are critical to the function of freshwater ecosystems, yet we still do not fully understand the factors that shape freshwater microbial communities. Furthermore, freshwater ecosystems are particularly susceptible to effects of environmental change, including influx of exogenous nutrients such as nitrogen and phosphorus. To evaluate the impact of nitrogen loading on the microbial community structure of shallow freshwater lakes, water samples collected from Lake Shenandoah (Virginia, USA) were incubated with two concentrations of either ammonium, nitrate, or urea as a nitrogen source. The potential impact of these nitrogen compounds on the bacterial community structure was assessed via 16S rRNA amplicon sequencing. At the phylum level, the dominant taxa in Lake Shenandoah were comprised of Actinobacteria and Proteobacteria, which were not affected by exposure to the various nitrogen treatments. Overall, there was not a significant shift in the diversity of the bacterial community of Lake Shenandoah with the addition of nitrogen sources, indicating this shallow system may be constrained by other environmental factors.

The prognosis of inflammatory bowel disease.

The complications of ulcerative colitis generally develop during the first two years of disease. The mortality is higher than expected and the highest likelihood of colectomy also occurs early in the disease. Mortality in Crohn's disease is greater than expected, especially in males. For both conditions, the overall mortality has decreased steadily, and currently is less than 5%. Ulcerative colitis is curable with proctocolectomy and ileostomy. In Crohn's disease, intestinal resection and reanastomosis is followed by recurrence in the majority of patients. The recurrence rate after proctocolectomy and ileostomy for Crohn's disease of the colon also is considerable, ranging from 20% to 35%. In ulcerative colitis, the more colon involved, the more frequent and more serious are the complications. In Crohn's disease, the anatomic pattern of disease tends to predict the type and extent of complications. Both ulcerative colitis and Crohn's disease appear to follow a more severe course in children and adolescents with "inflammatory bowel disease." Patients with either ulcerative colitis or Crohn's disease are at increased risk for the later development of cancer. In ulcerative colitis, the excess risk is limited to colorectal cancer. Patients with Crohn's disease have increased cancer rates for both the small and large bowel. Finally, most patients with these diseases are able to maintain normal occupations and enjoy reasonably stable social and economic situations. The successful adaptation of patients with inflammatory bowel disease is influenced by a hopeful, optimistic personality and by an encouraging, supportive physician.

Pancreas abscess: a fatal complication of endoscopic cholangiopancreatography (ERCP).

Endoscopic retrograde cholangiopancreatography (ERCP) is a popular and extremely useful technique for investigating the pancreatico-biliary tree. While the mortality is low, rare complications i.e., pancreatic abscess, may prove lethal. Surgical backup must be available to obviate recognized complications following ERCP.