Effect of in vitro exposure to tributyltin on generation of oxygen metabolites by oyster hemocytes.

Mollusks depend chiefly on hemocyte-mediated cytotoxic mechanisms such as reactive oxygen species (ROS) to defend against pathogenic microorganisms. The effect of in vitro tributyltin chloride (TBT) exposure on ROS generation by oyster (Crassostrea virginica) blood phagocytes is quantified in this study. Luminol-augmented chemiluminescence (LCL) was used to measure ROS activity of resting and zymosan-stimulated cells after 1 or 20 hr TBT exposure. LCL is thought to measure primarily the activity of the myeloperoxidase/hydrogen peroxide/ halide antimicrobial pathway. Hemocytes in TBT-free medium (controls) produced low level LCL, which was markedly stimulated by the addition of zymosan particles. Both resting and zymosan-stimulated LCL values were significantly inhibited by > or = 80 ppb TBT after either 1 or 20 hr of exposure. Exposure to < or = 2 ppb TBT concentrations for 20 hr produced slightly enhanced LCL activity, suggesting a hormesis-like effect. Partial reversibility of TBT suppression of LCL took place when previously exposed cells were put in TBT-free medium. The TBT concentrations used in these studies were not cytolethal in vitro and were considerably less than oyster tissue levels recorded after chronic, sublethal in vitro exposures. The data suggest that the common aquatic contaminant TBT can interact rapidly with C. virginica hemocytes to produce a partially reversible immunotoxicological lesion. Xenobiotic-induced suppression of ROS production by hemocytes may increase host susceptibility to infectious diseases.

Metallothionein mRNA induction and generation of reactive oxygen species in molluscan hemocytes exposed to cadmium in vitro.

(1) Hemocytes of the oyster Crassostrea virginica were exposed to Cd in vitro to examine the concomitant induction of metallothionein (MT) mRNA and production of reactive oxygen species (ROS) during the oxidative burst response of phagocytic cells. (2) MT mRNA induction was concentration-dependent, exhibiting a threshold between 5 and 10 microM cdCl2, and an increase at higher Cd concentrations up to a maximum level of 36 microM cdCl2. Continued increases in the Cd exposure concentrations resulted in declines in the levels of MT mRna. (3) No significant effects of Cd on ROS production were observed at Cd concentrations up to 36 microM CdCl2. However, ROS production decreased in a concentration-dependent fashion at CdCl2 concentrations from 36 to 356 microM, the highest concentration tested. (4) At these higher concentrations of Cd, the concomitant decrease in MT mRNA inducibility and suppression of ROS production were probably manifestations of the general cytotoxicity of Cd. ROS suppression can result in reduced resistance to infectious agents, suggesting that Cd is immunotoxic to C. virginica.

Chronic parastomal ulcers: spectrum of dermatoses.

Parastomal ulcers that develop after stoma surgery have reportedly been associated with recurrent inflammatory bowel disease and chronic infection. We report 13 patients with refractory parastomal ulcers, which occurred at a mean of 11 years after surgery. Parastomal ulcers in eight patients were the result of dermatologic conditions (e.g., contact dermatitis, bullous pemphigoid, lichen sclerosus et atrophicus, eczema, or psoriasis) or contact ulcers from dermatitis of the skin around the stoma and faceplate pressure. These ulcers healed after treatment with topical medications at a mean of 4 weeks. Five patients with inflammatory bowel disease had pyoderma gangrenosum ulcerations, which healed with systemic treatment at a mean of 25 weeks. Thus nonpyoderma gangrenosum parastomal ulcerations that occur late after stoma surgery require early enterostomal therapy nursing intervention and dermatologic evaluation, since they respond rapidly to appropriate local therapy.

Refractory parastomal ulcers: a multidisciplinary approach.

Chronic parastomal ulcers in patients with ileostomy or colostomy stomas are unusual. Previous reports have implicated infections, fistulas, recurrent inflammatory bowel disease (IBD), pyoderma gangrenosum, and trauma. Over the past 8 years we have evaluated 10 cases of such refractory parastomal ulcers that occurred at a mean of 11 years after stomal surgery. Eight patients had had an ileostomy for IBD while two had undergone colostomy for colon cancer. Five patients with IBD were diagnosed as having pyoderma gangrenosum ulcerations. They required systemic treatment for a mean of 25 weeks to effect ulcer healing. The other five patients had either parastomal ulcers on the basis of dermatoses (contact dermatitis, eczema, or bullous pemphigoid) or contact ulcers due to face-plate pressure and parastomal dermatitis. These patients received topical treatment with healing of ulcers in a mean of 4 weeks. We conclude that parastomal ulcers occurring in patients without IBD or IBD patients without classic pyoderma gangrenosum require early dermatologic evaluation as they respond relatively quickly to appropriate local therapy.

The role of endoscopic injection sclerotherapy in the management of bleeding peristomal varices.

Peristomal varices usually occur in patients with enterostomies who develop portal hypertension, and represent a cause of recurrent or intractable gastrointestinal bleeding. Treatment options for such bleeding include surgical ligation of varices, stoma revision with devascularization, injection sclerotherapy, portacaval shunt, or liver transplantation. We reviewed the records of seven patients with peristomal varices, who were followed for a mean of 17 months after diagnosis. Fourteen episodes of clinically significant peristomal bleeding occurred in six patients. Surgical ligation of varices was ineffective in controlling bleeding in two of three patients, although stoma revision with devascularization was temporarily effective in two other patients. Injection sclerotherapy, used in three patients, effectively controlled acute bleeding without serious complications or need for surgery. Definitive treatment for peristomal bleeding (portacaval shunt or liver transplantation) has prevented any further bleeding in three patients for a mean of 8 months after surgery.