Interactive effects of mosquito control insecticide toxicity, hypoxia, and increased carbon dioxide on larval and juvenile eastern oysters and hard clams.

Mosquito control insecticide use in the coastal zone coincides with the habitat and mariculture operations of commercially and ecologically important shellfish species. Few data are available regarding insecticide toxicity to shellfish early life stages, and potential interactions with abiotic stressors, such as low oxygen and increased CO2 (low pH), are less understood. Toxicity was assessed at 4 and 21 days for larval and juvenile stages of the Eastern oyster, Crassostrea virginica, and the hard clam, Mercenaria mercenaria, using two pyrethroids (resmethrin and permethrin), an organophosphate (naled), and a juvenile growth hormone mimic (methoprene). Acute toxicity (4-day LC50) values ranged from 1.59 to >10 mg/L. Overall, clams were more susceptible to mosquito control insecticides than oysters. Naled was the most toxic compound in oyster larvae, whereas resmethrin was the most toxic compound in clam larvae. Mortality for both species generally increased with chronic insecticide exposure (21-day LC50 values ranged from 0.60 to 9.49 mg/L). Insecticide exposure also caused sublethal effects, including decreased swimming activity after 4 days in larval oysters (4-day EC50 values of 0.60 to 2.33 mg/L) and decreased growth (shell area and weight) in juvenile clams and oysters after 21 days (detected at concentrations ranging from 0.625 to 10 mg/L). Hypoxia, hypercapnia, and a combination of hypoxia and hypercapnia caused mortality in larval clams and increased resmethrin toxicity. These data will benefit both shellfish mariculture operations and environmental resource agencies as they manage the use of mosquito control insecticides near coastal ecosystems.

The role of duplex scanning in decision making for patients with claudication.

The aim of this study was to compare the accuracy of clinical decisions made for patients presenting with claudication on the basis of the ankle/brachial index (ABI) (at rest and postexercise) and duplex scanning with that made on the basis of angiograms. Fifty-six patients presenting with a history suggestive of claudication had the ABI taken at rest. Seven patients could not be exercised but their resting ABI was <0.8. Additional exercise testing was done in 49 patients; two were then excluded as there was no fall in the ABI. Thus, 54 patients were entered into the study and underwent color-flow duplex scans and angiography. A clinical decision was reached independently on the basis of the results of ABI and duplex scans as to a) conservative treatment, b) angioplasty, and c) surgery. This was compared to the decision reached on the basis of angiograms. The results show that the combined use of ABI (as a screening test) and duplex scanning can replace angiography for clinical decision making in nearly 80% of claudicants. Angiography will only be needed when duplex scans are inconclusive.

The role of duplex scanning in the diagnosis of lower limb arterial disease.

Color flow duplex imaging of the iliac and femoropopliteal arteries was performed in patients undergoing angiography. The aim of the study was to determine: (1) in what percentage of patients could the iliac arteries be adequately visualized to enable a diagnosis, (2) the overall accuracy of duplex scanning in the diagnosis of arterial disease, and (3) whether there is a useful duplex criterion for the selection of patients for angioplasty. One hundred and twenty patients (79 males, 41 females; mean age 64.4 years) had duplex scans prior to angiography (2-7 days) and the results were compared. The duplex criteria of an increase in the peak systolic velocity ratio (PSVR) >2 and lesions <5 cm were used to signify hemodynamically significant stenosis (>50% narrowing), the presence of plaque and calcification in the arterial wall with alteration of PSVR and lesions >5 cm, diffuse disease, and the absence of flow on color/Doppler interrogation, occlusion. The results show that duplex scanning is a useful screening tool and may be effectively used to diagnose iliac and femoropopliteal disease in nearly 80% of patients. Angiography will be needed in those in whom duplex scanning is inconclusive, or, prior to intervention in those with disease suitable for surgical reconstruction or angioplasty, diagnosed on the basis of duplex scans.

Embolization of iatrogenic venous pseudoaneurysm.

A case is described where a patient on long-term anticoagulation developed a venous pseudoaneurysm in the antecubital fossa following venepuncture. This venous pseudoaneurysm was successfully treated with coil embolization.

Ultrasonic image analysis of the arterial wall in atherosclerosis.

BACKGROUND: Atherosclerotic carotid artery plaques can be classified on the basis of their ultrasound appearance according to the pattern of echolucency and echogenicity. The most commonly used classification is the one described by Gray-Weale who defined 4 plaque types. METHODS: The images of the carotid and femoral arteries of 9 healthy volunteers and 21 non-insulin dependent diabetic patients were analysed. In this study 16 atherosclerotic carotid artery plaques were imaged by B-mode high resolution ultrasonography and then subjected to analysis of the digitised images. RESULTS: The results show that the plaques could be separated into 3 groups according to their echogenic properties. Gray-Weale plaques types 2 and 3 could not be distinguished and it is proposed that these should be classified as a single group. CONCLUSIONS: An increased echogenicity in the intima-media complex of non-insulin dependent diabetics as well as a relationship with risk factors for the development of cardiovascular disease and with the ultrasound score could not be determined in this study.

Successful non operative management of late infrainguinal polytetrafluoroethylene vascular graft infection with antibiotics alone: a report of two cases.

Polytetrafluoroethylene (PTFE) prosthetic vascular graft infection is a serious complication of arterial reconstructive surgery. Traditional management is primarily surgical and may result in long hospital stay with significant morbidity and mortality. The authors describe two cases of infected femoropoliteal PTFE grafts which were managed non operatively with antibiotic therapy alone, resulting in early return to normal activities and excellent resolution of infection on Indium labelled leucocyte scanning. The authors suggest that in selected cases antibiotic therapy alone is a valuable tool in the management of infrainguinal PTFE prosthetic sepsis.

Sphincter preservation for low rectal carcinoma--the Durban experience.

With the increasing interest in sphincter preservation in the treatment of low rectal carcinoma, we retrospectively reviewed the present surgical options--sphincter preservation with colo-anal anastomosis, and the radical abdominoperineal resection (APR). Seventeen patients had sphincter preservation with colo-anal anastomosis and 12 an APR; 53% of the sphincter preservation group survived, compared with 25% of those patients who had APR. We conclude that in selected cases sphincter preservation would not compromise the chance of cure and would save the patient from a permanent colostomy.

Adenomatous polyp at the ureterocaecal anastomosis.

A case of adenomatous polyp occurring at a ureterocaecal anastomosis, 25 years after urinary diversion following a total cystectomy for carcinoma of the bladder, is reported. Bilateral nephrectomy for chronic pyelonephritis was carried out 25 years after the initial surgery and, following this, a sinus formed at the incision at the right loin. A sinogram showed contrast filling the right ureter and caecum, and outlined a lobulated filling defect at the ureterocaecal anastomosis. Subsequent histology revealed a dysplastic tubulovillous adenoma. The clinical presentation and management of tumours at the ureterointestinal junction are discussed.

False aneurysm of the brachial artery: an unusual complication following accidental puncture by a patient on home haemodialysis.

A case is reported of false aneurysm of the brachial artery following accidental puncture during attempted cannulation of the median cubital vein for routine haemodialysis at home. The merits of early diagnosis and prompt surgical repair are discussed.

Massive gangrene of the colon--a complication of fecal impaction. Report of a case.

A case of extensive gangrene of the colon secondary to fecal impaction is reported. The role of ischemia in the management of colonic obstruction and the pathogenesis and treatment of colonic gangrene are discussed.

Adenocarcinoma at the ileo-cutaneous junction following subtotal colectomy for ulcerative colitis. Case report.

Adenocarcinoma of the ileo-cutaneous junction is exceedingly rare. We report a case. The clinical presentation and pathogenesis are discussed.

Herbivory by crabs and the control of algal epibionts on Caribbean host corals.

A short-term experiment was conducted to examine the relationships among the branching coral Porites porites, algal epibionts, and a facultative crab associate Mithrax sculptus in Belize, Central America. Initial field observations suggested that coral colonies supporting resident crabs generally had lower algal cover than colonies without crabs. The hypothesis was tested that Mithrax significantly depresses host coral algal cover and thereby indirectly affects host survivorship and growth. Crab accessibility to an array of coral colonies, similarly covered with algal epibionts, was manipulated in three treatments. Results strongly support the hypothesis, with significant differences in algal cover (primarily Dictyota spp.) noted among treatments after only one month. Caged heads with crabs included and uncaged natural controls allowing crabs free access averaged less than 10% cover, whereas mean algal cover exceeded 75% where crabs were excluded. The uncaged treatment, in which crabs were allowed free access to Porites heads was not significantly different from the crab inclusion treatment. Collectively, these results demonstrate that under natural conditions, crabs can have pronounced effects on host corals by reducing fouling algal epibionts. Furthermore, these facultative coral associates may have more important, albeit localized effects on Caribbean corals than has been suggested previously.

Tuberculosis of the parotid gland in a child.

Tuberculosis of the parotid gland is exceedingly rare in children. We report a case of an 8-year-old caucasian girl with tuberculosis of the parotid gland. The clinical presentation and management are discussed.