2,4,6-triamino-1,3,5-trinitrobenzene (TATB) and TATB-based formulations--a review

This paper reviews the research and development work on 2,4,6-triamino-1,3,5-trinitrobenzene (TATB), and TATB-based formulations of other explosives. Syntheses including the production of nano-sized particles, analytical methods, thermophysical properties, performance, formulations, toxicity and safety of TATB are reviewed in this work.

Toxicity of trinitrotoluene to sheepshead minnows in water exposures

Lethal effects of trinitrotoluene (TNT) to juvenile sheepshead minnows (JSHM) (Cyprinodon variegatus) were assessed in ten-day water exposures. Ten-day median lethal concentrations (LC50s) were 2.3 and 2.5 mg L(-1), the 10-d median lethal residue value (LR50) was 26.1 micromol kg(-1) wet weight (ww), and bioconcentration factors (BCFs) ranged from 0.7 to 2.4 L kg(-1). The lethal effects of TNT and its transformation products 2-aminodinitrotoluene (2-ADNT), 2,4-diaminonitrotoluene (2,4-DANT) and trinitrobenzene (TNB) to JSHM were compared in 5-d static-renewal exposures. Nitroreduction decreased the toxicity of TNT to SHM, as the 5-d LC50 for 2-ADNT was 8.6 mg L(-1) and the lowest lethal concentration of 2,4-DANT was 50.3 mg L(-1). TNB (5-d LC50=1.2 mg L(-1)) was more toxic than TNT to SHM. The 5-d LR50s were 4.3 mg kg(-1)ww (20.4 micromol kg(-1)) for SumTNT (TNT exposure) and 54.2 mg kg(-1)ww (275.3 micromol kg(-1)) for 2-ADNT and significant mortality occurred at 47.4 mg kg(-1)ww (283.6 micromol kg(-1)). The range of BCF values was from 1.8 to 2.4, 5.6 to 8.0, and 0.6 to 0.9Lkg(-1) for TNT, 2-ADNT, and 2,4-DANT, respectively.

Parental dietary effect on embryological development response to toxicants with the sea urchin Arbacia punctulata

The role of echinoid parental nutrition in early-life stage toxicity is not well understood. Arbacia punctulata were fed either a fresh diet consisting of organic lettuce and carrots or a dry feed. Embryos from parents fed the dry feed exhibited lower sensitivity to copper, whereas the opposite occurred with 1,3,5-trinitrobenzene and sodium dodecyl sulfate (SDS). EC(50) values for the dry and fresh feed treatments, respectively, were 41.0 and 29.9 microg/L for copper, 0.5 and 1.8 mg/L for 1,3,5-trinitrobenzene, and 3.5 and 5.6 mg/L for SDS. The data suggests that nutritional standardization for sea urchins in ecotoxicological laboratories needs to be addressed and further investigated.

Heme oxygenase (HO-1) is involved in the negative regulation of contact sensitivity reaction

Cutaneous contact sensitivity (CS) is a subtype of delayed-type sensitivity and is mediated by either CD4(+) or CD8(+) CS-effector T cells. CS can be induced by skin painting with haptens like trinitrophenyl chloride (TNP-Cl).We have previously shown that CS is under the negative regulation of T regulatory cells (Treg) induced by the iv injection of a high dose of homologous antigen or via epicutaneous application of any protein antigen prior to TNP-Cl painting. In this study, we examined the role of heme oxygenase (HO-1) in the negative regulation of CS in mice. We found that ip injection of heme, an inducer of HO-1, before TNP-Cl sensitization strongly suppresses CS when compared to uninjected controls. Using a transfer out protocol, we showed that suppressor activity can be transferred with lymph node and spleen cells isolated from mice treated with heme for 7 days before TNP-Cl or sham immunization, which suggests a lack of antigen specificity of observed suppression. Negative selection with monoclonal antibodies and complement showed that regulatory cells induced via heme injection belong to the population of TCRalphabeta+ lymphocytes. Using CBA/J (H-2(k)), SJL (H-2(s)), and DBA1 (H-2(q)) mice, we showed that the suppression mediated by HO-1 is major histocompatibility complex (MHC) unrestricted. In vitro treatment of heme induced Treg cells with tin protoporphyrin IX (SnPPIX), an inhibitor of HO activity, prior to adoptive transfer abolished the suppressor activity. In summary, injection of heme results in the induction of antigen non-specific and MHC unrestricted TCRalphabeta+ Treg that suppress CS response in mice, possibly in a HO-1-dependent manner.

A structural modelling study on marine sediments toxicity

Quantitative structure-activity relationship models were obtained by applying the Molecular Descriptor Family approach to eight ordnance compounds with different toxicity on five marine species (arbacia punctulata, dinophilus gyrociliatus, sciaenops ocellatus, opossum shrimp, and ulva fasciata). The selection of the best among molecular descriptors generated and calculated from the ordnance compounds structures lead to accurate monovariate models. The resulting models obtained for six endpoints proved to be accurate in estimation (the squared correlation coefficient varied from 0.8186 to 0.9997) and prediction (the correlation coefficient obtained in leave-one-out analysis varied from 0.7263 to 0.9984).

Toxicities of dinitrotoluenes and trinitrobenzene freshly amended or weathered and aged in a sandy loam soil to Enchytraeus crypticus

Scientifically based ecological soil-screening levels are needed to identify concentrations of contaminant energetic materials (EMs) in soil that present an acceptable ecological risk at a wide range of military installations. Insufficient information regarding the toxicity of 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), and 1,3,5-trinitrobenzene (TNB) to soil invertebrates necessitated toxicity testing. We adapted the standardized Enchytraeid Reproduction Test (International Standardization Organization 16387:2003) and selected Enchytraeus crypticus for these studies. Tests were conducted in Sassafras sandy loam soil, which supports relatively high bioavailability of nitroaromatic EMs. Weathering and aging procedures for EMs amended to test soil were incorporated into the study design to produce toxicity data that better reflect the soil exposure conditions in the field compared with toxicity in freshly amended soils. This included exposing hydrated, EM-amended soils in open glass containers in the greenhouse to alternating wetting and drying cycles. Definitive tests established that the order of EM toxicity to E. crypticus based on the median effect concentration values for juvenile production in either freshly amended or weathered and aged treatments was (from the greatest to least toxicity) TNB > 2,4-DNT > 2,6-DNT. Toxicity to E. crypticus juvenile production was significantly increased in 2,6-DNT weathered and aged soil treatments compared with toxicity in freshly amended soil, based on 95% confidence intervals. This result shows that future investigations should include a weathering and aging component to generate toxicity data that provide more complete information regarding ecotoxicological effects of energetic contaminants in soil.

Effects of topical treatment of sodium butyrate and 5-aminosalicylic acid on expression of trefoil factor 3, interleukin 1beta, and nuclear factor kappaB in trinitrobenzene sulphonic acid induced colitis in rats

BACKGROUND AND AIMS

Butyrate enemas have been shown to be effective in treatment of ulcerative colitis, but the mechanism of the effects of butyrate is not totally known. This study evaluates effects of topical treatment of sodium butyrate (NaB) and 5-aminosalicylic acid (5-ASA) on the expression of trefoil factor 3 (TFF3), interleukin 1beta (IL1beta), and nuclear factor kappaB (NFkappaB) in trinitrobenzene sulphonic acid (TNBS) induced colitis in rats.

METHODS

Distal colitis was induced in male Wistar rats by colonic administration of TNBS and colonically treated with NaB, 5-ASA, combination of NaB and 5-ASA, and normal saline for 14 consecutive days. Colonic damage score, tissue myeloperoxidase (MPO) activity, TFF3 mRNA expression, serum IL1beta production, and tissue NFkappaB expression were determined, respectively.

RESULTS

Treatment of NaB, 5-ASA, and the combination improved diarrhoea, colonic damage score, and MPO activities, increased TFF3 mRNA expression, and decreased serum IL1beta production and tissue NFkappaB expression. The combination therapy of NaB and 5-ASA had better effects than any other single treatment.

CONCLUSIONS

The combination of topical treatment of NaB and 5-ASA was effective for relieving and repairing colonic inflammation and the effects were related to stimulation of TFF3 mRNA expression and down-regulation of IL1beta production and NFkappaB expression.

Comparative and mixture sediment toxicity of trinitrotoluene and its major transformation products to a freshwater midge

The explosive trinitrotoluene (TNT) is a prevalent contaminant in many military installations worldwide. Limited knowledge of the comparative toxicity of sediment-associated TNT and related compounds contributes to uncertainty when assessing ecological risks in contaminated sites. Trinitrotoluene undergoes transformation when associated with soils and sediments and typically occurs as a mixture dominated by its reduction products. The objective of this study was to comparatively evaluate the single-compound toxicity of TNT and its major transformation products to the freshwater midge Chironomus tentans in 10-day exposures to sediment spiked with TNT, 2-aminodinitrotoluene (2-ADNT), 2,4-diaminonitrotoluene (2,4-DANT), or trinitrobenzene (TNB). In addition, the nature of the toxicological interactions of the latter compounds in a mixture was evaluated. Upon spiking to sediment, TNT and TNB rapidly degraded to reduced products, and disappearance of extractable compounds suggested irreversible binding to sediment particles. The high degree of transformation and reactivity occurring during 10 days at spiking concentrations as high as 4000 micromol/kg dry weight suggests that TNT and related compounds are unlikely to be encountered in fine-grained sediments at contaminated sites. Similar to previous investigations, the high reactivity of the spiked compound hampered determination of accurate toxic concentrations of TNT and related compounds, and of the nature of toxicological interaction of compounds in a mixture in this study. Sediment concentrations associated with decreased survival were similar for all four compounds, with the 10-d median lethal concentrations (LC50s) determined using initial concentrations ranging from 175 (2-ADNT) to 605 (2,4-DANT) micromol/kg dry weight. Sublethal decrease in growth was not observed for any compound. Results from the mixture experiment suggest additive interaction among TNT and related compounds in sediment exposures.

Effects of 1,3,5-Trinitrobenzene on cytotoxicity and metabolic activity of type I astrocytes of rats

1,3,5-Trinitrobenzene (TNB) is a munitions chemical that causes gliovascular lesions in the brain stem of rats similar to those produced by thiamine deficiency and nitroaromatic compounds, including m-dinitrobenzene. To identify neuropathic indices of toxicity, the effects of varying concentrations (0 to 2 mM) of TNB on cytotoxicity and cellular metabolic activity were examined using cultured astrocytes from Fischer-344 rats. The cytotoxicity was assessed by lactate dehydrogenase (LDH) leakage into the culture medium. Astrocyte metabolic activity was assessed by measuring the conversion of a tetrazolium salt to a formazan product. Additionally, the effects of oxidative stress on cellular metabolic activity were determined by varying oxygen tension via alteration of culture media depth. In vitro, the toxic concentration 50% (TC50) of TNB, which induced cell death, was 16 microM following a 24-h exposure. The concentration of TNB that reduced cellular metabolic activity by 50% was 29 microM following a 24-h exposure. Varying the depth of the culture media did not influence the cellular metabolic activity in control or TNB-treated astrocytes. These results support the hypothesis that TNB induced neurotoxicity could partially be mediated via injury to astrocytes, a major component of the blood-brain barrier.

On-line monitoring of cell growth and cytotoxicity using electric cell-substrate impedance sensing (ECIS)

An on-line and continuous technique based on electric cell-substrate impedance sensing (ECIS) was developed for measuring the concentration and time response function of fibroblastic V79 cells exposed to mercury chloride and 1,3,5-trinitrobenzene (TNB). Attachment, spreading and proliferation of V79 fibroblastic cells cultured on a microarray of small gold electrodes precoated with fibronectin were detected as resistance changes. The response function was derived to reflect the resistance change as a result of cell attachment, spreading, mitosis and cytotoxicity effect. Exposure of V79 cells to mercury chloride or TNB led to alterations in cell behavior, and therefore, chemical cytotoxicity was easily screened by measuring the response function of the attached and spread cells in the presence of inhibitor. The half inhibition concentration, the required concentration to achieve 50% inhibition, was obtained from the response function to provide information about cytotoxicity during the course of the assay. A simple mathematical model was developed to describe the responses of ECIS that were related to the attachment, spreading, and proliferation of V79 fibroblastic cells. The novel results of this paper are mainly characterized by the systematic study of several parameters including the cell number, detection limit, sensor sensitivity, and cytotoxicity, and they may motivate further research and study of ECIS sensors.

Toxicity of sediment-associated nitroaromatic and cyclonitramine compounds to benthic invertebrates

The toxicity of nitroaromatic (2,4-diaminonitrotoluene [2,4-DANT] and 1,3,5-trinitrobenzene [TNB]) and 14C-labeled cyclonitramine compounds (hexahydro-1,3,5-trinitro-1,3,5-triazine [RDX] and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine [HMX]) to the marine polychaete Neanthes arenaceodentata and the estuarine amphipod Leptocheirus plumulosus following 10- or 28-d exposures to spiked sediments was investigated. Organismal-level effects on survival, growth, and reproduction and cellular-level effects on apoptosis (programmed cell death) were evaluated. Because cyclonitramines have low affinity for sediment, overlying water was not exchanged in the RDX and HMX exposures. Nitroaromatics sorbed strongly to sediment, resulting in near complete resistance to solvent extraction. Cyclonitramines sorbed weakly to sediment, as more 14C-activity was found in the overlying water than in the sediment at exposure termination. No significant decrease in survival or growth was observed with cyclonitramines at initial sediment concentrations as high as 1,000 microg/g. Survival was significantly affected by nitroaromatics at nominal sediment concentrations as low as 200 microg/g, with L. plumulosus being more sensitive than N. arenaceodentata. Growth was significantly decreased at sublethal concentrations of 2,4-DANT for N. arenaceodentata. Reproduction, measured only with L. plumulosus, was significantly decreased only in the highest RDX treatment and also in the lower TNB treatment. However, no decrease was observed in higher concentrations of TNB. Body burden at exposure termination was below detection limit (1 microg/kg) for all compounds. Significant inhibition of apoptosis was not accompanied by significant decreases in growth or reproduction. Because of its critical function in many biological processes. alterations in this endpoint may result in adverse effects on the organism and could be used as an early indicator of toxicity.

Chronic toxicity of 1,3,5-trinitrobenzene in Fischer 344 rats

The chronic toxicity of 1,3,5-trinitrobenzene (TNB) in male and female Fischer 344 (F344) rats was evaluated by feeding a diet containing 0, 5, 60, and 300 ppm of TNB for 2 years. The calculated average TNB intake over 2 years for males and females was 0.22, 2.64, 13.44 and 0.23, 2.68, 13.31 mg/kg body weight (BW)/day respectively. Terminal body weights were decreased and water intake was increased in both sexes (300 ppm), whereas food consumption was decreased in males (60 and 300 ppm groups) only. The relative spleen weights were significantly decreased in both sexes (300 ppm), whereas the relative brain weights were increased in females only (300 ppm). Hematological effects were not observed in animals killed at the 2-year time point, except significant decrease in the mean corpuscular hemoglobin (MCH) in males (300 ppm) and in females (60 and 300 ppm). Methemoglobin levels were increased in both sexes in the high dose group. Histopathological examination showed treatment-related changes in the kidney (hyaline droplets; 60 and 300 ppm) and the spleen (erythroid cell hyperplasia and pigment deposition; 300 ppm) of both sexes. Cytoplasmic hyaline droplets in the kidneys were characterized by immunohistochemistry as alpha-2mu-globulin. We propose a chronic, oral no-observable-adverse-effect level (NOAEL) of 2.68 mg/kg BW/day for TNB in the rat, based on the hematological and renal changes.

Use of a Salmonella microsuspension bioassay to detect the mutagenicity of munitions compounds at low concentrations

Past production and handling of munitions has resulted in soil contamination at various military facilities. Depending on the concentrations present, these soils pose both a reactivity and toxicity hazard and the potential for groundwater contamination. Many munitions-related chemicals have been examined for mutagenicity in the Ames test, but because the metabolites may be present in low environmental concentrations, a more sensitive method is needed to elucidate the associated mutagenicity. RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), TNT (2,4,6-trinitrotoluene), tetryl (N-methyl-N-2,4,6-tetranitroaniline), TNB (1,3,5-trinitrobenzene) and metabolites were examined for mutagenicity in a microsuspension modification of the Salmonella histidine reversion assay with and without metabolic activation. TNB and tetryl were positive in TA98 (32.5, 5.2revertants/nmole) and TA100 (7.4, 9.5revertants/nmole) without metabolic activation and were more potent than TNT (TA98, 0.3revertants/nmole; TA100, 2.4revertants/nmole). With the exception of the tetranitroazoxytoluene derivatives, TNT metabolites were less mutagenic than TNT. RDX and two metabolites were negative in both strains, however, hexahydro-1,3,5-trinitroso-1,3,5-triazine was positive in TA100 with and without S9. Microsuspension bioassay results tend to correlate well with published Ames test data, however, there are discrepancies among the published data sets and the microsuspension assay results.

Cytotoxic and genotoxic effects of energetic compounds on bacterial and mammalian cells in vitro

The mutagenicity and toxicity of energetic compounds such as 2,4, 6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), hexahydro-1,3, 5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3, 5,7-tetrazocine (HMX), and of amino/nitro derivatives of toluene were investigated in vitro. Mutagenicity was evaluated with the Salmonella fluctuation test (FT) and the V79 Chinese hamster lung cell mutagenicity assay. Cytotoxicity was evaluated using V79 and TK6 human lymphoblastic cells. For the TK6 and V79 assays, TNB and 2, 4,6-triaminotoluene were more toxic than TNT, whereas RDX and HMX were without effect at their maximal aqueous solubility limits. The primary TNT metabolites (2-amino-4,6-dinitrotoluene, 4-amino-2, 6-dinitrotoluene, 2,4-diamino-6-nitrotoluene and 2, 6-diamino-4-nitrotoluene) were generally less cytotoxic than the parent compound. The FT results indicated that TNB, TNT and all the tested primary TNT metabolites were mutagenic. Except for the cases of 4-amino-2,6-dinitrotoluene and 2,4-diamino-6-nitrotoluene in the TA98 strain, addition of rat liver S9 resulted in either no effect, or decreased activity. None of the tested compounds were mutagenic for the V79 mammalian cells with or without S9 metabolic activation. Thus, the FT assay was more sensitive to the genotoxic effects of energetic compounds than was the V79 test, suggesting that the FT might be a better screening tool for the presence of these explosives. The lack of mutagenicity of pure substances for V79 cells under the conditions used in this study does not preclude that genotoxicity could actually exist in other mammalian cells. In view of earlier reports and this study, mutagenicity testing of environmental samples should be considered as part of the hazard assessment of sites contaminated by TNT and related products.

Neurotoxicity of 1,3,5-trinitrobenzene (TNB): immunohistochemical study of cerebrovascular permeability

1,3,5-Trinitrobenzene (TNB) is a soil and water contaminant at certain military installations. Encephalopathy in rats given 10 daily oral doses of TNB has been reported. The lesion was bilaterally symmetric vacuolation and microcavitation in the cerebellar roof nuclei, vestibular nuclei, olivary nuclei, and inferior colliculi. The contribution of the blood-brain barrier (BBB) in the genesis of these lesions remains uncertain. One of the main goals of the present work was to evaluate the functional state of the BBB. Male Fischer 344 rats (five rats/group) were euthanatized after four, five, six, seven, eight, or 10 daily doses of TNB (71 mg/kg). A different set of rats (five rats/group) was allowed to recover for 10 or 30 days after receiving 10 doses of TNB. Integrity of the BBB was assessed by immunohistochemical staining for extravasated plasma albumin on paraffin-embedded sections. Rats euthanatized after four to eight doses had no lesions, and albumin extravasation in the susceptible regions of the brain was minimal. Rats receiving 10 daily doses of TNB had bilaterally symmetric vacuolation and microcavitation in the cerebellar nuclei, vestibular nuclei, and inferior colliculi in association with multifocal, often confluent foci of extravasated albumin in susceptible nuclei. Albumin was present in vascular walls, extracellular space, and neurons. Immunoreactivity in neurons was of two types: cytoplasmic staining representing pinocytic uptake and homogeneous staining of the entire neuron (nucleus and cytoplasm) due to uncontrolled albumin leakage through the damaged cell membrane. In rats allowed to recover for 10 days, the microcavitated foci were infiltrated by glial and gitter cells. Albumin immunoreactivity was present as extracellular granular debris, and neuronal staining (for albumin) was mild. In rats allowed to recover for 30 days, immunoreactivity to albumin was not seen. This study demonstrates that TNB-mediated tissue damage is accompanied by breakdown of the BBB. The presence of vacuolation and associated extravasated serum proteins in TNB-treated rats is an indication of vasogenic brain edema, which appears to be a critical event in TNB toxicity. Additional studies are needed to determine the reason for selective regional vulnerability and brain microvascular susceptibility to TNB.

Assessment of environmental hazards of 1,3,5-trinitrobenzene

The remedial investigation/feasibility studies conducted at certain Army installations showed a need to clean up contaminated sites, where high levels of ammunition chemicals such as 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), 1,3-dinitrobenzene (DNB), and their degradation products/metabolites were detected in surface soil and groundwater. TNB is a photodegradation product of TNT; it is not easily degraded, and persists in the environment. The toxicity data on TNB are scanty. Hence the U.S. Environmental Protection Agency in 1988 (U.S. EPA, 1997) developed a reference dose (RfD) for TNB (0.00005 mg/kg/d for chronic toxicity) based on the toxicity of DNB, which is structurally similar to TNB. Since then we have completed acute, subacute, subchronic, chronic, reproductive, and developmental toxicity studies and toxicokinetics studies. We have reviewed the mammalian toxicity data for TNB and have determined the no observed adverse effect levels (NOAEL) and low observed adverse effect levels (LOAEL) for subchronic, chronic, reproductive, and developmental toxicity. Based on the newly determined NOAEL and LOAEL values, we have now developed a new RfD for TNB (0.03 mg/kg/d), based on the chronic toxic effects on hematology and histopathological changes in testes and kidney.

1,3,5-Trinitrobenzene-induced alpha-2u-globulin nephropathy

Male and female Fischer-344 (F-344) and male NCI-Black-Reiter (NBR) rats were dosed with 0, 35.5, or 71 mg 1,3,5-trinitrobenzene (TNB)/kg/day for 10 days. Male F-344 rats were dosed with TNB (0 and 35.5 mg/kg) for 20 and 30 days. Hematoxylin and eosin and Mallory-Heidenhain stains and alpha-2u-globulin and proliferating cell nuclear antigen immunohistochemical stains were performed on kidney sections. All treated male F-344 rats exhibited dose-related accumulation of hyaline droplets containing alpha-2u-globulin in proximal tubules. The kidney weights were significantly increased in male and female rats treated with TNB. Significant increases in cell proliferation in proximal tubules were observed in male F-344 rats. Renal changes observed in TNB-treated rats appeared identical to those from other chemicals that induce alpha-2u-globulin nephropathy in male rats. No hyaline droplet accumulation was found in female F-344 and male NBR rats at any doses. We can conclude that TNB induces dose-related exacerbation of hyaline droplets containing alpha-2u-globulin in male rat kidney and subsequent cell proliferation.

Testicular effects of 1,3,5-trinitrobenzene (TNB). I. Dose response and reversibility studies

Testicular effects of TNB were characterized after single and multiple oral doses of TNB at 0, 35.5, and 71 mg/kg. Male Fischer 344 (F344) rats were killed after a single dose or after 4 and 10 daily doses of TNB. Testicular effects were not evident at the light microscope level in rats killed after a single dose of TNB or after 4 daily doses at 35.5 mg/kg of TNB. Rats receiving 4 daily doses of TNB at 71 mg/kg had the earliest evidence of testicular damage, with necrosis and degeneration of pachytene spermatocytes including a significant decrease in testicular weight. Rats dosed at 35.5 mg/kg for 10 d had severe testicular lesions, in addition to the decrease in testicular weight. There was degeneration of round and elongate spermatids, and formation of multinucleate syncytial cells. The epididymis was devoid of sperm, instead containing exfoliated syncytial spermatids. Rats dosed at 71 mg/kg of TNB for 10 d had testicular atrophy and cessation of spermatogenesis. These rats also had apoptic cells in the ventral prostate. To assess the extent of reversibility in these atrophied testis, rats were allowed to recover for 10 or 30 d after 10 doses of TNB (71 mg/kg). A significant regenerative attempt with proliferating spermatocytes were present at 10 d and elongate spermatids were evident at 30 d. These reversibility studies indicate testicular effects of TNB are at least partially reversible.

Testicular effects of 1,3,5-trinitrobenzene (TNB). II. Immunolocalization of germ cells using proliferating cell nuclear antigen (PCNA) as an endogenous marker

The applicability of PCNA as a tool for the analysis of germ cells in rats treated with 1,3,5-trinitrobenzene (TNB), a potent testicular toxicant, was evaluated. Male Fischer 344 (F344) rats were gavaged with TNB at 71 mg/kg or with corn oil (vehicle). Rats were killed after 10 daily oral doses or were allowed to recover for 10 or 30 d after the 10 doses. Testes from control rats, treated rats, and rats allowed to recover were immunohistochemically stained for PCNA. PCNA labeling in the control rats was confined to the nuclei of spermatogonia, pachytene spermatocytes, and nuclei of elongate spermatocytes. Conventional (hematoxylin and eosin) staining of testes from rats treated with TNB at 71 mg/kg for 10 d revealed loss of germ cells and cessation of spermatogenesis. Immunohistochemical staining of sections from these treated rats revealed only PCNA-positive spermatogonia. Rats allowed a 10-d recovery had both spermatogonial and spermatocytic staining, indicating partial restoration of germ-cell population. In rats allowed to recover for 30 d, the PCNA staining pattern was identical to the control rats. These results indicate that PCNA can be used to assess the proliferative status of spermatogonia (germ cells) in rodent testes exposed to testicular toxicants.

Mixture toxicity of nitrobenzene and trinitrobenzene using the marine bacterium Vibrio harveyi as the test organism

Vibrio harveyi, a bioluminescent marine bacterium, was used to evaluate combined or mixture toxicity of two organic compounds, nitrobenzene and trinitrobenzene. An estimated median effective concentration (EC50) and confidence interval were determined for each chemical. These chemicals at their EC50 were evaluated in combination and an additive index method was used to determine a numerical toxicology value. Combinations at 20% intervals of the EC50 were performed using isopleths. The isopleths employed were the isobole plot and the isobologram. Bioluminescent change was also determined and graphed for evaluation of toxicity. Statistical evaluation of isopleths and the additive index method were employed by incorporating confidence intervals. Bioluminescent change and isopleths suggest that mixtures of nitrobenzene and trinitrobenzene are additive, while the additive index method is suggestive of synergism. Statistical evaluation between mixtures and single values, using the z test, was in some cases different at the 5% level. These data suggest that interaction of combinations should be evaluated and described by multiple methodologies. Evaluation of these data suggests, in part, that one mixture is statistically different for antagonism. This study supports the use of bioluminescent microbial toxicity tests with various evaluative methodologies for the determination of mixture interactions.

Two-dimensional electrophoresis of precision-cut testis slices: toxicologic application

Advances in tissue slice technology and a recent novel application of this technique to reproductive toxicology using bovine testis have demonstrated the remarkable utility of this approach. The objective of the present study was to combine this in vitro toxicity test system with large-scale two-dimensional polyacrylamide gel electrophoresis (2-DE) to detect and study alterations in testicular-slice protein patterns as molecular correlates of 1,3,5-trinitrobenzene (TNB) and 1,3-dinitrobenzene (DNB) toxicity. Previous studies have shown that testicular slices remain viable for > 24 h and, as measured by protein synthesis inhibition, TNB causes dose-related injury. Tissue-slices were prepared from bovine testicles incubated for 2, 4 or 6 h and exposed to either 100 microM, 500 microM or 1 mM DNB or TNB in the incubation medium. Slices were collected, solubilized, and separated by large scale 2-DE. Resulting protein patterns were then examined by image analysis, which revealed coefficients of variation in protein spot abundance comparable to patterns from fresh rodent tissue samples. Furthermore, specific protein alterations indicated dose-related inductions and declines in protein abundance, some progressive over time. The results of this investigation demonstrate the potential toxicologic utility of combining in vitro tissue-slice technology with high-resolution 2-DE protein mapping. The consolidation of these methods offers a novel approach for toxicity screening and testing, reduces experimental cost, and reduces the use of laboratory animals.

Induction and prevention of colonic inflammation in IL-2-deficient mice

Gene-targeted mice deficient for IL-2 (IL-2 -/- mice) are free of apparent disease when maintained under germfree conditions but develop colitis and autoimmunity in a conventional environment. Here we show that colitis can be reproducibly induced in IL-2 -/- mice, but not in IL-2 +/+ mice, by i.p. immunization with Ag in CFA; thus enabling the systematic study of the immunopathogenesis of the colitis. We found that TNP-KLH or TNP-OVA had the most significant effect in inducing colitis, and while TNP-KLH immunization leads to the early appearance of activated T cells in the colons of both IL-2 -/- and IL-2 +/+ mice, only lamina propria cells of IL-2 -/- mice produced high amounts of INF-gamma. Moreover, both infiltrating colon CD4+ (69%) and CD8+ (6%) T cells secrete large amounts of IFN-gamma; however, only the depletion of CD4+ T cells leads to abrogation of the inflammation. In further analysis, we showed that the high IFN-gamma production is IL-12 driven, since colonic tissues of IL-2 -/- mice but not IL-2 +/+ mice show the presence of heterodimeric IL-12 and co-administration of anti-IL-12 with TNP-KLH completely prevented colitis and significantly reduced IFN-gamma production. Finally, we demonstrate that IL-2 -/- mice are deficient in their ability to induce Th2 responses after TNP-KLH challenge and that such immunization also leads to autoimmune-like phenomena in other organs of IL-2 -/- mice. These findings suggest that in the absence of IL-2 systemic administration of Ag induces primarily Th1 cells driven by overexpression of heterodimeric IL-12.

Fourteen-day toxicity study of 1,3,5-trinitrobenzene in Fischer 344 rats

Toxic effects of 1,3,5-trinitrobenzene (TNB) in male and female rats were evaluated by feeding powdered certified laboratory chow diet supplemented with varied concentrations of TNB (0, 50, 200, 400, 800 and 1200 mg kg-1 diet) for 14 days. Food intake by female rats in 400, 800 and 1200 mg TNB diet groups was reduced and resulted in a significant decrease in absolute body weights (BW). Food and water consumption by male rats in high-dose groups (800 and 1200 mg TNB kg-1 diet) was also reduced and resulted in a significant decrease in body weight. The calculated average TNB intake (from 1200 mg TNB kg-1 diet) was 92 mg kg-1 BW day-1 for male rats and 80 mg kg-1 BW day-1 for females. A decrease in testicular weight in males and an increase in spleen weight of both sexes in high-dose groups was noted. In addition, histopathological examinations revealed that the susceptible organs for TNB toxicity were kidney (hyaline droplets), spleen (extramedullary hematopoiesis), brain (hemorrhage, malacia and gliosis) and testes (seminiferous tubular degeneration). Hematology and clinical chemistry studies indicated a decrease in red blood cell count and hematocrit, a decrease in alkaline phosphatase, an increase in Heinz bodies and increased methemoglobin concentration as compared to controls in both sexes. A lowest observed adverse effect level of 4.41 mg TNB kg-1 BW day-1 was established based on the findings of this study.

Hematological effects of 1,3,5-trinitrobenzene (TNB) in rats in vivo and in vitro

We studied the hematological effects of single and repeated exposure to 1,3,5-trinitrobenzene (TNB) in rats. Male F-344 rats were gavaged with TNB at 35.5 and 71 mg/kg in corn oil. Blood was collected 5 h and 24 h after a single oral dose or 24 h after daily oral doses for 4 or 10 d in four different set of experiments. A dose-dependent methemoglobinemia was present only in blood collected 5 h after a single dose. A highly significant dose-dependent anemia with reduced red cells, hemoglobin, and hemotocrit was present in rats receiving TNB for 4 or 10 d. A dose-dependent decrease in serum triglycerides was present in rats receiving TNB for 10 d. There was no hemolysis when rat erythrocytes were incubated with TNB (in vitro) for 9 h. Spectral changes of hemoglobin recorded during the incubation with TNB confirm methemoglobin formation and progressive denaturation of hemoglobin-forming hemichromes. The significance of methemoglobin and hemichrome formation is discussed, and a probable hypothesis for the hemolytic anemia is suggested.

1,3,5-Trinitrobenzene-induced encephalopathy in male Fischer-344 rats

Administration of 1,3,5-trinitrobenzene (TNB) to male Fischer-344 rats produced ataxia after 6 or 7 oral doses (71 mg/kg). Light microscopic examination after 10 days revealed petechial hemorrhages in the brain stem and cerebellum and bilaterally symmetric degeneration and necrosis (malacia) with reactive gliosis in the cerebellar peduncles. The malacia was dorsal and lateral to the fourth ventricle involving the cerebellar nuclei, medial and lateral vestibular nuclei, and inferior colliculi. Blood vessels associated with the lesion had widened Virchow-Robin spaces, occasionally with extravasated erythrocytes. Rats administered daily oral doses of 35.5 mg/kg of TNB for 10 days and 35.5 and 71 mg/kg of TNB for 1 or 4 days did not have brain lesions.

Reproductive toxicity screen of 1,3,5-trinitrobenzene administered in the diet of Sprague-Dawley rats

Several Army installations targeted for restoration have measurable quantities of 1,3,5-trinitrobenzene (TNB) in the soil and groundwater. As part of the process of developing environmental and health effects criteria for restoration, a modified Screening Information Data Set (SIDS) reproductive study was performed. Male and female Sprague-Dawley rats received a diet containing approximately 30, 150, or 300 mg TNB/kg diet. Mating occurred following 14 days of treatment. All dams, one-half the males, and representative pups were maintained for a total of 90 days of treatment. No mortality occurred during the study; however, a decrease in mean body weights was noted in both sexes of high-dose rats. A dose-related effect was noted in measurements of sperm function/activity. Sperm depletion and degeneration of the seminiferous tubules were noted histopathologically. Methemoglobinemia and splenic hemosiderosis were common findings in the high- and mid-dose levels of both sexes at necropsy. No adverse effects were noted in mating or fertility indices. No significant treatment-related differences were found in length of gestation, sex ratio, gestation index, or mean number of pups per litter.