The Genotoxic Potential of Linear Alkylbenzene Mixtures in a Short-Term Test Battery

Alkylate 215 (A-215), Alkylate 225 (A-225), and Alkylate 230(A-230) are mixtures of C₁₀–C₁₄ linear alkylbenzenes usedas intermediates for the manufacture of detergents. These productswere evaluated for genotoxic activity in the Ames bacterialmutagenesis assay (strains TA98, 100, 1535, and 1537), the CHO/HGPRTmammalian cell forward gene mutation assay, and the in vivorat bone marrow chromosome assay. The Ames and CHO/HGPRT assayswere conducted both with and without the addition of Aroclor-inducedrat liver S9. The maximum concentrations evaluated were 10 mg/plate(A-215) and 3 mg/plate (A-225 and A-230) for the Ames test,and 1.5 mg/ml (A-215 and A-225) and 2.0 mg/ml (A-230) for theCHO/HGPRT assay. In each case, the highest concentrations producedevidence of either toxicity or insolubility. The highest dosein the bone mar row cytogenetics assay was 12,700 mg/kg, a levelwhich produced significant weight loss. The results of all testswere negative, indicating a lack of genotoxic activity as measuredby the battery of tests used.     

RENAL TRANSPLANTATION – AN EARLY EXPERIENCE

Renal transplant (RT) is now a therapy of choice for end stage renal disease (ESRD). The Nephrology Unit, Asvini started functioning in Dec 90 and to date 1298 sittings of hemodialysis have been given to 45 patients. Of these, 35 were in ESRD and 11 patients underwent renal transplantation at this hospital during the period Jan 91 – Dec 93. One patient expired after 18 months of transplantation due to infection. Early experience in screening patients for RT, use of immunosuppression, management of rejection episodes and protocol are presented with special emphasis on its relevance to the Armed Forces.KEY WORDS: Transplantation, Renal Failure, Immunosuppression, Rejection     

Toxicity of Calcium Sodium Metaphosphate Fiber: I. In Vitro and in Vivo Degradation and Clearance Studies

In an experiment to ascertain the degradability of calcium sodiummetaphosphate (CSM) fiber in vitro, ³²P-labeled CSM fiber wasincubated in media with or without rat lung epithelial cells(LEC) or rat alveolar macrophages (RAM). The amount of radioactivityappearing in the filtrate of the media in the presence of cellsminus the radioactivity in the media in the absence of cellswas considered to reflect cell-aided dissolution of the fiber.LEC and RAM cells increased the degree of dissolution two- andsevenfold, respectively, compared to their respective mediacontrols in a 7-day time period. In a separate experiment, maleFischer rats were given ³²P-labeled CSM fiber either by intraperitonealinjection or by intratracheal instillation and the amount ofradioactivity appearing in the urine and feces was measuredover a period of 60 days. Selected animals from this experimentwere also subjected to whole-body autoradiography 0, 1, 5, 15,30, and 60 days postexposure. After intraperitoneal injection,approximately 0.9% of the administered dose appeared in theurine. A similar percentage of the dose was eliminated in theurine when the fibers were administered by intratracheal instillation;however, the amount of radioactivity in the feces after intratrachealinstillation, i.e., 11.6% of the administered dose, was muchhigher than that after intraperitoneal dose, i.e., 0.24% ofthe administered dose. Whole-body autoradiographs showed a time-relatedincrease in radioactivity at a site other than the site of administration,and the location of this radioactivity appeared to be exclusivelyassociated with mineralized tissue. The clearance of nonradiolabeledCSM fiber (approximately 200,000 fibers) from rat lung afterintratracheal inhalation (IH) and intratracheal instillation(IT) was monitored. Approximately 93% of the initial fiber loadafter IH and approximately 84% of the initial fiber load afterIT was cleared from the lung in 6 months. Histological and biochemicalevaluation of the rat lungs did not reveal any indication offibrosis up to a period of 6 months. All the studies discussedindicate that CSM is de-gradable in biological systems and iscleared from the lung after IT and IH administration. Theseattributes of CSM fiber should reduce the potential for chronicadverse effects in the lung after inhalation.     

VASCULAR EMBOLOTHERAPY-HOW MUCH HAS BEEN ACHIEVED?

Emergency and elective embolotherapy of various systemic arteries in 64 patients was carried out at a tertiary centre of Armed Forces. Specific indications were haemoptysis (n=43), preoperative (n=18), haematuria (n=1), epistaxis (n=1) and chemoembolization (n=1). The procedures were performed with gelfoam pellets (n=46), gelfoam pellets and absolute alcohol (n=1), polyvinyl alcohol particles (PVA) (n=14), steel coils (n=2) and Adriamycin-in-oil emulsion (n=1). Embolotherapy resulted in complete haemostasis in 37 (82.2%) out of 45 cases of haemorrhage. In eight cases (17.8%), it resulted in significant improvement. Complete haemostasis was achieved in both cases of haematuria and epistaxis. Pre-operative embolotherapy resulted in considerable reduction of peroperative blood loss in all the cases. Chemoembolization of Hepatocellular carcinoma resulted in partial regression of the tumour. The purpose of this study was to assess the efficacy, safety and reliability of vascular embolotherapy for control of life threatening haemorrhage and preoperative reduction of lesions.KEY WORDS: Embolization, Embolotherapy, Haemorrhage     

Radicular cyst affecting a root-filled human tooth: a long-term post-treatment follow-up

Apical periodontitis is caused primarily by microorganisms residing in the root canals of affected teeth. Nevertheless, there is convincing evidence implicating other independent factors that adversely affect the outcome of conventional root canal therapy. In this paper, morphological evidence is presented in support of die potential role of two endogenous factors that may interfere with post-endodontic healing of the periapex. The specimens consisted of a surgical biopsy of an asymptomatic peri-apical lesion which persisted for a follow-up period of 44 months. The biopsy was processed for correlated light and electron microscopy. The lesion was characterized by the presence of a large central lumen lined by a stratified squamous epithelium. The most striking feature of the lesion was the presence of vast numbers of cholesterol crystals which congregated in the connective tissue surrounding the cyst cavity. Extensive light and electron microscopic investigation of the apical part of the root canal and the lesion foiled to reveal the presence of microorganisms. These findings strongly suggest that intrinsic factors like the accumulation of certain tissue break-down products such as cholesterol crystals, and the cystic condition of the lesion itself, can adversely affect the healing process of the periapex following root canal therapy. Consequently, such apical lesions can remain refractory to conventional endodontic therapy for long periods of time.