Contribution of nitrosobenzene to splenic toxicity of aniline

To elucidate the mechanism(s) of splenic toxicity of aniline, studies were conducted with nitrosobenzene (NB), an N-oxidized metabolite of aniline. Male Sprague-Dawley rats were given 0.025, 0.05, 0.1, or 0.2 mmol/kg/d of NB in 0.5 ml of 0.25% agar by gavage for 4 d; control rats received the vehicle only. Animals were euthanized at 24 h following the last dose. NB treatment resulted in decreased erythrocyte counts, whereas methemoglobin content increased at 0.1- and 0.2-mmol/kg doses. Spleen weight to body weight ratios were greater by 55 and 81% at O.1- and 0.2-mmol/kg NB doses, respectively. Total iron content in the spleens of NB-treated rats showed dose-dependent significant increases, and the nonheme iron followed a similar pattern. Splenic lipid peroxidation showed a dose-dependent response and was greater by 19, 56, 74, and 85% at the 4 doses, respectively. Malondialdehyde (MDA)-protein adducts, as quantitated by a competitive enzyme-linked immunosorbent assay (ELISA), were markedly greater in all the NB-treated groups, with the highest increase of 248% at 0.2 mmol/kg. Furthermore, NB exposure also resulted in greater protein oxidation (carbonyl content) in the spleens at 0.1- and 0.2-mmol/kg doses. These results suggest that NB is a splenotoxin and therefore can contribute to the splenic toxicity of aniline. Results of this study further support our earlier findings that oxidative stress is a potential mechanism in the splenotoxicity of aniline.

Multivisceral transplantation for megacystis microcolon intestinal hypoperistalsis syndrome

BACKGROUND

Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a rare autosomal recessive disorder causing a functional neonatal bowel obstruction. Its etiopathogenesis is not fully understood. The prognosis is poor in the majority of cases; most patients die before the age of 6 months. In this report, we describe our experience with three patients with MMIHS in whom multivisceral transplantation was performed.

METHODS

Three patients with MMIHS underwent multivisceral transplantation. All patients were females with a history of long-term total parenteral nutrition (TPN) with TPN-related cholestatic liver disease.

RESULTS

Patient 1 died 17 months after transplantation because of aspiration after revision of her feeding gastrostomy. At the time of death, the graft was functioning and the patient was completely off TPN. Patient 2 is alive 17 months after transplant. She is a fully functional, active 2-year-old and has also recently begun oral feeding after intensive rehabilitation. Patient 3 died on day 44 of multisystem failure.

CONCLUSIONS

This is the first report in the literature of multivisceral transplantation for MMIHS. Although one of the three patients died 44 days after surgery from multiorgan system failure, the other two patients had long-term survival after transplant and both grew well on enteral feeding alone. One patient died 17 months from a non-transplant-related complication, while the other is living at home off of TPN, with almost complete dietary rehabilitation 17 months after transplant. Our case reports suggest that multivisceral transplantation is a valuable therapeutic option for patients affected by MMIHS with TPN-induced liver failure.

Iron exacerbates aniline-associated splenic toxicity

Our earlier studies have shown that aniline exposure in rats causes time- and dose-dependent accumulation of iron in the spleen, which may exacerbate aniline splenotoxicity by catalyzing free-radical reactions. The present studies were conducted to test whether aniline-induced splenic toxicity could be potentiated by iron overload. For 30 d male Sprague-Dawley rats received the following treatments: 0.5 mmol/kg/d aniline hydrochloride (AH) by gavage (AH group); 3% carbonyl iron-supplemented diet (IR group); 0.5 mmol/kg/d AH by gavage and iron-supplemented diet (AH + IR group); or no treatments (controls). Treatment-related significant increases in total iron, low molecular weight chelatable iron, lipid peroxidation, and protein oxidation were observed in the spleens of all the groups compared to control. However, these changes were much greater in the combined AH + IR group. The aniline-induced morphological changes in the spleen were consistent with our earlier observations, but were more pronounced in the AH + IR group. The increased toxicity, as evident from greater oxidative stress and morphological changes in the AH + IR group, suggests that iron potentiates the splenic toxicity of aniline.

Thrombocytopenia after liver transplantation

BACKGROUND

Thrombocytopenia after orthotopic liver transplantation (OLT) is a well recognized and prevalent early postoperative complication. The etiology, as well as the effect of this phenomenon on transplant outcome, however, are vague. The aims of this study are to identify factors contributing to thrombocytopenia and to ascertain whether there is any correlation with early rejection and ultimate survival.

METHODS

This study examines 541 OLTs (541 grafts in 494 patients) that were transplanted at the University of Miami during the 3-year period from June 1994 to September 1997. The patients with severe postoperative thrombocytopenia (nadir platelet count [PLT] < 20,000/mm3), as well as the whole group of patients, were analyzed. The preoperative PLT, intra-operative platelet transfusion requirements, cross-match, recipient and donor cytomegalovirus (CMV) status, infusion of donor bone marrow cells (DBMC), occurrence of early rejection episodes (in the first posttransplant month), and re-transplantation were factors examined for any association with thrombocytopenia. Total bilirubin (TB) and direct bilirubin (dB), hematocrit, white blood cell count (WBC), aspartate aminotransferase and alanine aminotransferase, determined on the day that platelets reached a nadir (nadir day), were also analyzed.

RESULTS

In 90.9% of the cases, there was a 56.5%+/-23.5% fall in platelets in the immediate posttransplant period (first 2 weeks), but the mean PLT exceeded preoperative levels during the 3rd and 4th postoperative weeks. The nadir of the drop in the PLT most commonly occurred on posttransplant day 4. For preoperative PLT, platelet transfusions during the operation, re-transplantation, early rejection, cross-match, and recipient CMV status, there was significant statistical correlation with any degree of postoperative thrombocytopenia. Four of these factors, preoperative PLT, intra-operative platelet transfusions, re-transplantation, and early rejection, were found to be independently associated with thrombocytopenia in general. None of them was found to be independently correlated with severe thrombocytopenia. A statistically significant correlation between bilirubin and WBC on the nadir day and the degree of thrombocytopenia was observed. No correlation was found between infusion of DBMC or donor CMV serology and thrombocytopenia. Both the nadir PLT and the percentage of the platelet fall were independent predictive factors (p<0.01 and 0.005, respectively) of patient and graft survival.

CONCLUSIONS

Thrombocytopenia in the immediate posttransplant period is correlated with low preoperative PLT, massive platelet transfusions, and re-transplantation. These factors reflect a poor preoperative condition. There is also a correlation with allograft dysfunction, rejection, and poorer patient and graft survival. A rise in the mean PLT after the 2nd postoperative week reflects proper graft function.

Oxidative modification of lipids and proteins in aniline-induced splenic toxicity

Our earlier studies with aniline suggested the involvement of oxidative stress as an early toxic event in the spleen. In order to understand the status and consequences of the damaging oxidative reactions, especially during the progression of characteristic splenic lesions, time-dependent subchronic studies were conducted in rats. Male Sprague-Dawley rats were treated with 65 mg/kg/day aniline in the drinking water, while control rats received drinking water only. The animals were euthanized after 1, 2, or 3 months of aniline exposure. Total iron content was remarkably greater in the aniline-treated rats than in age-matched controls. There were time-dependent increases in splenic lipid peroxidation of aniline-treated rats. Malondialdehyde-protein adducts were quantitated by a competitive ELISA and showed greater concentrations in the spleens of aniline-treated rats, further substantiating our lipid peroxidation results. Protein oxidation in the spleens of aniline-treated rats was also greater, with a maximum increase of approximately 76% at 3 months. Western blot analysis for oxidized proteins showed two distinct protein bands at approximately 114 kD and approximately 69 kD in both post-nuclear and mitochondrial fractions of the spleens. Furthermore, densitometric analysis of the blot showed increased band intensities of the oxidized proteins in both these spleen fractions from aniline-treated rats, suggesting the susceptibility of these proteins to aniline-induced oxidative stress. The most prominent morphological changes in the spleens of aniline-treated rats included thickening of the capsule, and capsular cells with nuclear prominence and hyperchromia indicative of capsular hyperplasia. These capsular changes and fibrosis of capsule, splenic trabeculae, and red pulp were noted at all three time points after aniline exposure. Our studies thus suggest that aniline-induced oxidative stress in the spleen is an ongoing event that leads to oxidative modifications of biomolecules. Such oxidative modifications, directly or indirectly, could contribute to the splenic toxicity leading to deleterious consequences, including capsular hyperplasia and fibrosis, as observed in this study, and possibly tumorigenesis in chronic aniline exposure conditions.

Study of microleakage at Class I cavities prepared by Er:YAG laser using three types of restorative materials

OBJECTIVE

The purpose of this in vitro study were to investigate microleakage at class I cavities filled with amalgam, composite resin, or glass-ionomer after preparation by Er:YAG laser and to compare the results with those by a conventional method using an air turbine.

SUMMARY BACKGROUND DATA

There has been no report of a study of microleakage on class I cavities prepared by Er:YAG laser.

METHODS

Ninety-six extracted human premolar and molar teeth were used in this study. Forty-eight class I cavities were prepared by Er:YAG laser and 48 class I cavities by air turbine. After preparation, each of the 2 groups was further subdivided into 3 groups, respectively, and cavities in each of these subgroups were filled by 1 of 3 types of restorative materials. Microleakage at the restored cavities was assessed by the dye penetration method and scanning electron microscopy (SEM).

RESULTS

Minimal or moderate leakage was evident at most of the composite resin or glass-ionomer restorations, whereas moderate or severe leakage was observed at most of the amalgam restorations as shown by the dye penetration method. There was significant difference among the 3 restorative materials (p < 0.05), but there was no significant difference in microleakage between the cavities prepared by Er:YAG laser and those by air turbine (p > 0.05). SEM evaluation demonstrated good adaptation with most of the composite resin or glass-ionomer restorations, but amalgam restorations showed slightly poorer adaptation.

CONCLUSION

These results suggest that Er:YAG laser is useful for class I cavity preparation from the viewpoint of microleakage.

Comparison of tacrolimus with microemulsion cyclosporine as primary immunosuppression in hepatitis C patients after liver transplantation

BACKGROUND

Immunosuppression in patients with hepatitis C virus (HCV) following orthotopic liver transplantation can lead to significant increases in serum viral loads. Our aim was to analyze the effect of a randomized study of two immunosuppressive agents (tacrolimus vs. microemulsion cyclosporine) on the outcome of HCV patients following orthotopic liver transplantation.

METHODS

From December 1995 to September 1996, 50 adult patients transplanted for HCV cirrhosis were randomly assigned to receive tacrolimus (Prograf) (group 1, 25 patients) or microemulsion cyclosporine (Neoral) (group 2, 24 patients). All patients received alpha-interferon after transplantation, and the overall steroid doses were no different between the groups. Serum RNA levels were measured by signal amplification of Chiron. Biopsies were taken when transaminases were greater than 2x base line or when there was an inappropriate response to alterations in immunosuppression regimens.

RESULTS

There were more episodes of rejection in the Neoral group, but there were no differences in bacterial and viral infections, nor in the rate of HCV recurrence between the two groups. There were seven deaths in group 1 and eight in group 2. Overall patient and graft survival rates in the Prograf and Neoral groups at 18 months were 72 and 68% and 67 and 64%, respectively.

CONCLUSIONS

(a) Both immunosuppression regimens had similar HCV recurrence rates; (b) there were no differences in bacterial or opportunistic infections; and (c) patient and graft survival was similar between the two groups.

The role of liver transplantation in the subacute trauma patients

Two case reports are presented involving complex liver traumas requiring the need for liver transplantation. Both of these patients were designated unsalvageable until the transplant team was consulted. It is imperative that surgeons involved with complex hepatic trauma not give up hope and include these patients as potential liver recipients when irreversible liver failure occurs.

Phenylhydroxylamine: role in aniline-associated splenic oxidative stress and induction of subendocardial necrosis

To elucidate the role of N-phenylhydroxylamine (PHA, N-hydroxylated metabolite of aniline) in the selective toxicity of aniline to the spleen, dose-dependent studies were conducted with PHA in rats. Male Sprague-Dawley rats were given four doses each (1 dose/day) of 0.025, 0.05, 0.1, or 0.2 mmol/kg PHA in 0.5 ml of aqueous agar (0.25%) by gavage. The control animals received an equal volume of vehicle only. The animals were euthanized 24 h following the last dose. PHA toxicity in the blood was evident from a dose-dependent increase of methemoglobin. The most affected organ was spleen, which appeared dark and enlarged (splenomegaly) and showed increased spleen-to-body weight ratios, which were 28, 40, 66, and 87% at PHA doses of 0.025, 0.05, 0.1, and 0.2 mmol/kg, respectively. Splenic lipid peroxidation (malondialdehyde content) was higher in all PHA-treated groups, whereas splenic protein oxidation (carbonyl content) increased in only the 0.05, 0.1, and 0.2 mmol/kg groups. The total iron content in the spleen also showed increases of 88, 135, 168, and 209% at PHA doses of 0.025, 0.05, 0.1, and 0.2 mmol/kg, respectively. These biochemical changes were accompanied by a dose-dependent vascular congestion in the spleen, a characteristic feature of aniline toxicity. Although the ratio of organ to body weight increased for both testes and heart at the highest dose, striking morphological changes were observed only in heart. The cardiac lesions consisted of a both acute and resolving multifocal subendocardial necrosis involving predominently the left ventricle. Our results suggest that PHA is a splenotoxin and thus contributes to the toxicity of aniline, while at a high dose, it is also cardiotoxic, perhaps due to anoxia associated with the marked methemoglobinemia. These results further support the involvement of oxidative stress in the splenotoxicity of aniline which may be caused by its reactive metabolite(s) such as PHA.

Donor biliary variations: an overlooked problem?

Documented causes of biliary complications following orthotopic liver transplantation have been related to technical imperfections or insufficient arterial supply. Although anatomical variations of the extrahepatic biliary system are not infrequent, neither their incidence, surgical management nor possible association with complications have been reported in liver transplantation. At our institution, the global incidence of biliary complications following 357 consecutive liver transplants performed in 324 patients over a 2-yr period was 15.4% (55/357). Anomalous donor extrahepatic ducts were verified in 10 cases (2.8%) and they were recognized intraoperatively, prior to biliary reconstruction, in 7 cases. Technical complications occurred in 1 of these 7 and in 3 other cases where the anomalous ducts were not identified until later in the postoperative period when serious clinical problems ensued. We herein present a description of these 10 cases, with reference to the techniques employed to manage the anatomical anomalies and to treat complications. As in any hepatobiliary procedure, awareness of possible variations of the extrahepatic biliary system, intraoperative identification of the anomalous ducts and appropriate tailoring of the surgical technique are advisable in order to avoid serious postoperative complications in liver transplantation.

'Domino' liver transplantation combined with multivisceral transplantation

Transplantation of the liver contemporaneously with another organ from the same donor is thought to confer an immunologic advantage. The latter is particularly desirable in intestinal transplantation because of the propensity of the intestinal graft to early and late rejections and because in some cases it may facilitate the operation. In clinical practice, shortage of liver grafts constrains liver transplantation to cases in which there is coexisting end stage liver disease.

Differential induction of polyamine oxidase activity in liver and heart of iron-overloaded rats

The present study was undertaken to investigate the effect of iron dextran treatment on polyamine oxidase (PAO) activity, iron accumulation, and lipid peroxidation in livers and hearts of rats. PAO catalyzes oxidative deamination of polyamines, the cellular aliphatic cations. This reaction produces highly toxic hydrogen peroxide, 3-acetamidopropanal, and precursors of higher polyamines. The rats were given iron dextran daily for 7 d. In iron-dextran-treated rats, a marked increase in the hepatic level of iron was associated with enhanced lipid peroxidation and increased PAO activity. Though iron accumulation and lipid peroxidation in the iron-treated rats increased significantly in the heart, PAO activity remained unchanged. The paraffin sections of livers stained with Perls iron stain showed the presence of iron in macrophages and hepatocytes. The sections of hearts showed iron deposits only in macrophages, while myocytes showed no iron staining. These results show that although iron dextran treatment results in accumulation of iron in both liver and heart, it induces PAO activity only in liver. The significance of increased PAO activity in lipid peroxidation and fibrosis in iron-mediated injury is discussed.

Acute hematopoietic toxicity of aniline in rats

In the present study, acute hematopoietic toxicity of aniline as a function of time was investigated in rats. The animals were given a single oral dose of aniline hydrochloride (2 mmol/kg) and euthanized at zero (control), 0.25, 0.5, 1, 3, 6, 12, 24 and 48 h following the treatment. The blood methemoglobin level increased dramatically and attained a peak level of 37% (31 fold greater than the controls) at 0.5 h. Thereafter, the increases were less pronounced and the level declined with time. Spleen weight to body weight ratio remained unchanged up to 24 h, but increased approximately 25% at 48 h. Lipid peroxidation (MDA content) in the spleen increased by 39% at 24 h and remained steady even at 48 h. MDA-protein adducts, as quantitated by a competitive ELISA, showed 94, 126 and 265% increases in the spleen homogenates at 12, 24 and 48 h, respectively, following the treatment. However, no changes were observed in the splenic protein oxidation. Morphological examination showed congestion of splenic blood vessels and marked expansion of red pulp at 24 and 48 h. These studies suggest that aniline related changes in the blood are reflected very early as evident from increases in the methemoglobin content, whereas changes in the spleen appear later and are characterized by splenic weight changes, increased lipid peroxidation, MDA-protein adduct formation and morphological changes after a single high dose exposure. The increased lipid peroxidation in the spleen also suggests that free radical-mediated reactions could be the potential mechanism of splenic toxicity of aniline and lipid peroxidation precedes protein oxidation.

Effect of laser treatment on the root canal of human teeth

The purpose of this study was to examine the morphological and temperature changes of the apical portion of human extracted teeth treated by Nd: YAG, CO2 and Argon-lasers. Seventy-two single-rooted human teeth were studied. The root canals were prepared conventionally. Laser treatment of the apical portion of the canal was carried out by means of an optic fiber or metal tip. Temperatures were recorded thermographically. Two-thirds of the specimens were stained with black India ink and 36% silver ammonium fluoride solution. All specimens were irradiated by the three types of lasers at several intensities and the temperatures were recorded. Half of the specimens were prepared for the telescopic light microscope and for scanning electron microscopic observation, and the rest for histopathological examination by light microscope. The scanning electron microscopic evaluation showed that the laser energy vaporized the deposited debris, producing a glaze-like surface. The histopathological investigation revealed a tapered, enlarged apical lased area. All three laser devices were capable of vaporizing the debris in this way but the degree of morphological change was highly dependent on energy level and duration. The Argon-laser produced the highest temperatures.

Time-dependent autoimmune response of dichloroacetyl chloride in female MRL +/+ mice

Welders are exposed to dichloroacetyl chloride (DCAC) when trichloroethene (TCE) is used as a degreasing agent. Human exposure to TCE and tetrachloroethane can also lead to formation of DCAC in situ through metabolism. Due to its strong acylating property, it can bind with cellular macromolecules and act as hapten and consequently may elicit autoimmune (Al) response. Earlier, we reported that both TCE and DCAC induce/accelerate Al response in MRL +/+ mice, and DCAC even at 50 fold lower concentration induced greater Al responses. These studies, however, were conducted at a single time point (six weeks of treatment) and therefore necessitate a time-dependent characterization of this DCAC-induced Al response. Female MRL +/+ were given ip treatments of 0.2 mmol/kg DCAC in 100 microliters of corn oil every 4th day, while controls received an equal volume of corn oil only. DCAC treatment resulted in spleen weight increases at all time points whereas serum IgG showed significant increases at 4, 6 and 8 weeks of treatment. Serum autoantibodies, i.e., antinuclear antibodies, anti-single stranded DNA antibodies and anticardiolipin antibodies showed positive responses only after 4 weeks of treatment. However, the optimal responses were observed at 6 weeks and subsequently the responses diminished (at 8 weeks). The DCAC-specific antibodies showed a pattern similar to autoantibodies, i.e., an optimal response at 6 weeks of treatment. Our results thus suggest that DCAC under the current experimental conditions induces an optimal Al response at 6 weeks of treatment and further emphasize the usefulness of MRL +/+ mice in studying chemical-induced autoimmunity.

Oxidative stress in the splenotoxicity of aniline

Aniline-induced splenic toxicity is characterized by hemorrhage, capsular hyperplasia, fibrosis, and a variety of sarcomas in rats. Early biochemical events responsible for the observed effects are not known. To understand the mechanism(s) of aniline-induced splenic toxicity, single and multiple (four and seven) doses of 1 mmol/kg of aniline hydrochloride(AH) were given in rats. Apart from changes in the hematological parameters, these studies demonstrated that AH could induce lipid peroxidation and protein oxidation in the spleen, and significant increases were observed at four doses. Subsequently, a dose-response study of AH was performed. Male SD rats were given four doses each (one dose/day) of 0.25, 0.5, 1, and 2 mmol/kg of AH in water by gavage, while controls received water only. Animals were euthanized 24 hr following the last dose and tissues obtained. Spleen weight increased by 32 and 80% at 1 and 2 mmol/kg doses, respectively. Splenic lipid peroxidation showed dose-dependent increases of 24, 32, and 43% at 0.5, 1, and 2 mmol/kg, respectively. Protein oxidation in the spleen, quantitated by carbonyl content per milligram protein, showed 10, 28, and 27% increases at 0.5, 1, and 2 mmol/kg, respectively. Iron content in the spleen also showed dose-dependent increases of 72, 172, and 325% at 0.5, 1, and 2 mmol/kg, respectively. Dose-related histopathologic expansion of splenic red pulp was characterized by increasing vascular congestion (most pronounced at 2 mmol/kg), increased red pulp cellularity, erythrophagocytosis, and cellular fragmentation at 1 and 2 mmol/kg; iron deposition in red pulp also increased dramatically with dose. These studies establish that aniline induces lipid peroxidation and protein oxidation in the spleen and suggest that oxidative stress plays a role in the splenic toxicity of aniline.

Trichloroethene-induced autoimmune response in female MRL +/+ mice

Trichloroethene (TCE) has been implicated in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE) and scleroderma in humans. However, experimental studies have not been conducted to establish the role of TCE in causing autoimmunity and/or SLE. To clarify the role of TCE in autoimmune responses, subchronic studies were carried out in female autoimmune prone mice (MRL +/+). Three groups of mice (5 weeks old) received intraperitoneal injections of 10 mmol/kg of TCE, 0.2 mmol/kg of dichloroacetyl chloride (DCAC) (one of the metabolites of TCE with strong acylating property), or an equal volume (100 microliters) of corn oil alone (controls). Animals were dosed every 4th day for 6 weeks and euthanized 24 hr following the last dose. Sera and major tissues were collected and analyzed. Spleen weights in the TCE and DCAC groups increased 36% with a similar pattern of change in the spleen-to-body weight ratios. Serum IgG in the TCE and DCAC groups increased 45 and 322%, respectively. Using specific ELISA assays for mice, autoimmune antibodies were detected in the sera of TCE- and DCAC-treated mice in the following patterns: for anti-nuclear antibodies; controls, 0/4; TCE, 4/4; DCAC, 3/5; for anti-ssDNA antibodies; controls, 0/4; TCE, 2/4; DCAC, 5/5; for anti-cardiolipin antibodies; controls, 0/4; TCE, 0/4; DCAC, 3/5. An ELISA developed for the measurement of DCAC-specific antibodies using conjugated DCAC-albumin as an antigen showed the following pattern: for controls, 0/4; TCE, 0/4; DCAC, 5/5. These results suggest that TCE and its metabolite, DCAC, induce and/or accelerate autoimmune responses in female MRL +/+ mice. The greater responses induced by DCAC at a dose 50 times lower than TCE suggests that this metabolite may be important in the mechanisms leading to TCE-induced autoimmunity.

Hematopoietic toxicity of linoleic acid anilide: importance of aniline

The purpose of this study was to investigate the role of hydrolysis products of linoleic acid anilide (LAA), i.e., aniline and linoleic acid (LA), in the toxicity to the hemopoietic system, especially to the spleen. To achieve this, the parent compound (LAA) and its putative hydrolysis products, i.e., aniline or linoleic acid (LA), were given to male SD rats at equimolar doses (0.7 mmol/kg) in 0.25 ml mineral oil by gavage, daily, for 14 days. The controls received equal volumes of vehicle only. Five animals from each group were euthanized at Days 1, 7, and 28 following the last dose. At all time points, spleen weights increased in the LAA- and aniline-treated rats, but spleen to body weight ratios were increased only at Days 1 and 7 in these groups. No changes were observed in the LA-treated rats at any time point. RBC counts were decreased in the LAA and aniline groups at Days 1 and 7, whereas hemoglobin content was decreased by 20 and 13% in the LAA- and aniline-treated rats, respectively, only at Day 1. Methemoglobin content in the LAA and aniline groups also increased by 76 and 101%, respectively, at Day 1. Serum transaminases (AST and ALT) decreased in the LAA, aniline, and LA groups but the decreases were more consistent in the LA group. Serum IgA increased in the LAA and aniline groups only at Day 1. Splenic iron content was increased 381, 486, and 51% in the LAA-treated rats and 474, 491, and 58% in the aniline-treated rats at Days 1, 7, and 28, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Erythrocyte-aniline interaction leads to their accumulation and iron deposition in rat spleen

In order to understand the splenic toxicity of aniline in rats, early interaction of aniline with erythrocytes and its subsequent deposition and covalent binding to macromolecules in target (spleen) and nontarget (liver) organs have been studied. Male Sprague-Dawley (SD) rats were given 1 or 3 doses of 1 mmol/kg [14C]aniline hydrochloride (1 dose/d) by gavage and euthanized 24 h after the treatment. Among blood components, maximum radioactivity was found to be associated with red blood cells (RBCs). After 3 doses, there was 112, 79, and 67% increase in the radioactivity in the whole blood, RBCs, and hemolysate, respectively, in comparison to 1 dose. In comparison to RBCs, plasma had only 40 and 16% radioactivity after the administration of 1 and 3 doses, respectively. Spleen homogenate at 1 dose had one-third of the radioactivity in the TCA precipitate, which increased to 40% at 3 doses, while the total radioactivity increased 256% over 1 dose. Liver, which had almost double the radioactivity on a per gram tissue basis compared to the spleen at one dose, did not show any appreciable increase in the radioactivity at three doses. However, radioactivity in the TCA precipitate of liver homogenate increased by 92% after 3 doses. The iron content of the spleen in rats given 3 doses of [14C]aniline increased by 85% compared to the rats given just 1 dose. The iron content of liver did not show any change at three doses. These data thus demonstrate a dose-dependent binding and accumulation of radioactivity in erythrocytes and spleen. These interactions, along with parallel increases in the iron content of the spleen, could be critical in the splenic toxicity of anilines.

Iron-induced lipid peroxidation in rat liver is accompanied by preferential induction of glutathione S-transferase 8-8 isozyme

Since previous studies from this laboratory have suggested that glutathione S-transferase (GST) 8-8 of rat belongs to a distinct subgroup of GST isozymes which may be involved in the detoxification of the products of lipid peroxidation (Zimniak et al., J. Biol. Chem. 269, 992-1000, 1994), during the present studies we examined the effect of iron-induced lipid peroxidation on the expression of GST 8-8 in rat liver. Rats treated with 100 mg/kg body wt iron showed a significant increase in lipid peroxidation in liver. This was accompanied by a concomitant increase in the expression of GST 8-8 in liver as observed in isoelectrophoretic analysis of rat liver GSTs, and an increase in GST activity toward 4-HNE, a toxic product of lipid peroxidation toward which GST 8-8 displays high specific activity. Western blot studies using polyclonal antibodies specifically recognizing GST 8-8 also indicated that, among the GST isozymes of rat liver, GST 8-8 was preferentially induced upon iron treatment. These findings were further confirmed by purifying and quantitating GST 8-8 protein from the controls and iron-treated rats. Significant differences in the specific activities of GST 8-8 purified from the controls and iron-treated rats were observed, indicating that more than one GST isozyme related to GST 8-8 may be present in rat liver. This observation is consistent with the observed heterogeneity in mouse mGSTA4-4 which is an ortholog of rat GST 8-8. Iron treatment also caused significant increase in GSH levels probably because of de novo synthesis as indicated by an increase in gamma-glutamyl cysteine synthetase activity. The results of these studies suggest that GST 8-8, and possibly other related GST isozymes, may play an important role in defense mechanisms against lipid peroxidation.