Delayed left ventricle-to-right atrial fistula following aortic valve replacement

Fistula development between the left ventricular outflow tract and right atrium is a rare complication of aortic valve replacement (AVR), typically seen with calcific aortic stenosis or endocarditis. The case is reported of a left ventricle-to-right atrial fistula following mechanical AVR for aortic insufficiency.     

Medullary carcinoma of the thyroid with parathyroid adenoma and hypercalcaemia

A patient with hyperparathyroidism due to a parathyroid adenoma was found to have metastatic medullary carcinoma in lymph nodes close to the thyroid gland. The finding of normal calcitonin and parathormone concentrations after removal of the adenoma suggested that the parathyroid lesion was not the result of the hypocalcaemic action of calcitonin produced by the tumour in the thyroid.Seventeen other examples of the association between medullary carcinoma and parathyroid enlargement are briefly reviewed.The pathogenesis of the parathyroid lesions is discussed, and it is suggested that some may be caused by the hypocalcaemic action of calcitonin, while others may be part of a syndrome of multiple endocrine adenomatosis.     

Borrelia burgdorferi in an urban environment: white-tailed deer with infected ticks and antibodies.

Ticks and blood samples were collected from white-tailed deer (Odocoileus virginianus) in forests located in an insular, urban area of Bridgeport, Conn., and in rural south central Connecticut during 1992 and 1993. Immature and adult Ixodes scapularis ticks were tested for Borrelia burgdorferi, the etiologic agent of Lyme borreliosis, by indirect fluorescent-antibody staining methods. Deer sera were analyzed for antibodies to this bacterium by an enzyme-linked immunosorbent assay. Infected ticks parasitized deer in Bridgeport from May through December; the prevalence of infection varied from 1.1% of 93 larvae to 28.1% of 114 adult females. The percentages of infected males (10.5% of 380 ticks) and females (13.7% of 328 ticks) were relatively lower in south central Connecticut. In antibody tests, the prevalence of seropositive specimens collected in Bridgeport (61% of 146 serum specimens) was more than twofold greater than that of specimens obtained in south central Connecticut (26.7% of 116 serum specimens). Foci for Lyme borreliosis can occur in forested, urban settings as well as in rural areas if there are ticks, rodents, birds, and large mammals present. Human exposure to ticks in such sites should be considered as a possible source of B. burgdorferi infection.     

Does glyceryl trinitrate cause central sympatholytic effects? Insights from a case of baroreflex failure

Whether part of the blood pressure lowering effects of glyceryl trinitrate (GTN) is the result of centrally mediated reduction in sympathetic activity is debated. In humans, baroreflex activity potentially obscures the central sympatholytic effects of GTN. We examined this in a routine clinical tilt test in a patient with baroreflex failure secondary to previous neck radiotherapy. With reduced baroreflex function we observed an exaggerated fall in blood pressure and reduced sympathetic activity with GTN, supporting a peripheral vasodilation and central sympatholytic effect.     

Have patients with esophagitis got an increased risk of adenocarcinoma？ Results from a population-based study

AIM: To examine an increased risk of esophageal adenocarcinoma is restricted to patients who develop Barrett's esophagus or whether esophagitis per is a risk factor for adenocarcinoma. METHODS: A population-based cohort of patients with histological evidence of esophagitis without Barrett's esophagus was constructed using electronic pathology reports relating to all esophageal biopsies in Northern Ireland between 1993 and 1996. Person-years of follow-up and incident cases of esophageal cancer were calculated by linking the cohort to death files and the Northern Ireland Cancer Registry records. Standardized incidence ratios (SIR) were calculated for esophageal cancers (adenocarcinoma, squamous cell carcinoma (SCC), and historically unspecified cancers). RESULTS: A total of 2 013 patients in the cohort provided 13 559 patient-years of follow-up (mean follow-up 6.7 years). None of the patients developed adenocarcinoma. Three patients developed SCC, and six developed histologically unspecified cancers. The SIR for all esophageal cancers and for SCC were 2.73 (95%CI 1.25-5.19) and 2.93 (95%CI 0.61-8.59), respectively. In a sensitivity analysis in which all unspecified esophageal cancers were treated as adenocarcinomas, the SIR for adenocarcinoma was 2.64 (0.97-5.75). CONCLUSION: The risk of adenocarcinoma is not elevated in patients with histological evidence of esophagitis without Barrett's esophagus; however, these patients may have a moderately increased risk of SCC. Further studies are required to confirm these findings, which suggest that Barrett's esophagus, not esophagitis, is the key precursor lesion in the development of adenocarcinoma.     

An Ixodes scapularis protein required for survival of Anaplasma phagocytophilum in tick salivary glands

Anaplasma phagocytophilum is the agent of human anaplasmosis, the second most common tick-borne illness in the United States. This pathogen, which is closely related to obligate intracellular organisms in the genera Rickettsia, Ehrlichia, and Anaplasma, persists in ticks and mammalian hosts; however, the mechanisms for survival in the arthropod are not known. We now show that A. phagocytophilum induces expression of the Ixodes scapularis salp16 gene in the arthropod salivary glands during vector engorgement. RNA interference-mediated silencing of salp16 gene expression interfered with the survival of A. phagocytophilum that entered ticks fed on A. phagocytophilum-infected mice. A. phagocytophilum migrated normally from A. phagocytophilum-infected mice to the gut of engorging salp16-deficient ticks, but up to 90% of the bacteria that entered the ticks were not able to successfully infect I. scapularis salivary glands. These data demonstrate the specific requirement of a pathogen for a tick salivary protein to persist within the arthropod and provide a paradigm for understanding how Rickettsia-like pathogens are maintained within vectors.