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Use of Nd-yag laser ablation in colorectal obstruction and palliation in high-risk patients

Conventional treatment for colonic obstruction due to cancer or benign anastomotic stricutres in high-risk patients or unresectable cases in some form of colostomy. This procedure has the negative aspects of requiring a general anesthetic and leaves the infirm patient with a stoma that they cannot easily attend to. Ablation of tumor by Nd-Yag laser has been available for several years, with passage of the laser fiber through a colonoscope. To evaluate the role of laser photocoagulation in the palliation of colorectal tumors or benign strictures, the authors summarized their initial experience, trying to define the indications, various methods of treatment, and complication rate in these patients. This technique is difficult to perform and has the added risk of intestinal perforation but does obviate anesthetic and surgical risks. Seven patients with recurrent metastatic colorectal obstruction, three patients with benign colonic strictures, and two patients with large villous tumors were treated with Nd-Yag laser passed via the colonoscope. The mean age was 71 years (range, 52 to 86 years). Five patients received sedatives only, six patients received epidural anesthetic, and one had a general anesthetic. The average total energy used was 3702 joules on noncontact fibers, and the average number of pulses was 126. Distance of the lesion from the anal margin ranged from 0.5 to 30 cm. Ten of twelve tumors were within 15 cm of the dentate line. In the most distal lesions, manual debulking with biopsy forceps facilitated the laser treatment. Symptomatic relief was achieved in all patients. One patient required a colostomy one month after treatment because of incontinence. Another patient needed a resection of a benign stricture after three laser treatments. Other than one case of microperforation, treated conservatively with antibiotics, no other complications occurred and there was no mortality. The authors believed that the Nd-Yag laser plays a specific role in the treatment of high-risk patients.

An early antigen‐presenting cell defect in HIV‐1‐infected patients correlates with CD4 dependency in human T‐cell clones

We have used a defined panel of nine HIV peptide‐specific T‐cell clones (TLC) generated from a healthy volunteer to evaluate the antigen‐presenting cell (APC) function of human immunodeficiency virus‐1 (HIV‐1)‐infected patients. Peripheral blood mononuclear cells (PBMC) from HLA‐matched seropositive and uninfected volunteers were compared for their capacity to present peptide to TLC specific for the V3 loop of HIV‐1 envelope glycoprotein gp120, influenza haemagglutinin or the mycobacterial 19 000 MW antigen. APC from uninfected volunteers (HIV−APC) invariably presented peptides to all TLC with comparable efficiency. In contrast, using APC from HIV‐1‐infected subjects (HIV+APC), three patterns of responsiveness were observed. The first group of TLC was not stimulated by HIV+APC, even early in infection. The second responded to all APC comparably. The third, and intermediate group, responded to APC from some clinically asymptomatic, but not acquired immune deficiency syndrome (AIDS), patients. The two additional TLC, derived from other donors and with specificity for non‐HIV peptides, showed similar variation in response to HIV+APC. The different patterns of response to HIV+APC did not correlate with the fine specificity or cytokine phenotypes of the TLC. Neither was the defect due to decreased levels of expression of APC molecules involved in delivering the first or second signal required for T‐cell activation. APC mixing experiments showed no evidence of APC‐derived inhibitory factors. Furthermore, the defect was independent of T cells or their products and was equally expressed in monocytes and dendritic cells. Instead, responsiveness was inversely related to the degree of CD4 dependency, suggesting that the underlying mechanism was a CD4 APC‐associated–gp120 interaction. The early appearance of this defect in HIV‐1 infection co‐incident with the loss of recall responses is consistent with a role for APC dysfunction in pathogenesis.

Mycoplasma fermentans and HIV-associated nephropathy

We describe a patient in whom HIV-associated nephropathy developed in association with the detection of Mycoplasma fermentans. This mycoplasma was found in renal tissue by means of a polymerase chain reaction when nephropathy was first evident, and subsequently in urine, blood and the throat. The evidence presented strengthens the causal association of this micro-organism with HIV-induced nephropathy.