C-Reactive Protein Mediating Immunopathological Lesions: A Potential Treatment Option for Severe Influenza A Diseases.

Severe influenza diseases with high mortality have been frequently reported, especially in those patients infected with avian influenza A (H5N1, H7N9 or H10N8) or during a pandemic. Respiratory distress, which is attributed to alveolar damage associated with immunopathological lesions, is the most common cause of death. There is a wealth of information on pathogenesis or treatment options. In this study, we showed that high levels of C-reactive protein (CRP) were induced and correlated with complement activation in patients infected with severe influenza A (H5N1, H7N9 or H10N8), and higher levels were induced in fatal patients than in survivors. CRP treatment enhanced the phagocytosis of monocytes THP-1 to H5N1 virus as well as the expression of proinflammatory cytokines or apoptosis-associated genes in THP-1 cells or pneumocytes A-549 respectively. CRP may link to proinflammatory mediators contributing to activation of complement and boosting inflammatory response in severe influenza infections. Compound 1,6-bis(phosphocholine)-hexane improved the severity and mortality of mice infected with lethal influenza virus significantly. These observations showed that CRP is involved in deterioration of severe influenza diseases, and indicated a substantial candidate molecule for immunotherapy of severe influenza diseases.

Biological exposure indices of pyrrole adducts in serum and urine for hazard assessment of n-hexane exposure.

BACKGROUND: Pyrrole adducts might be used as a biomarker for monitoring occupational exposure to n-hexane, but the Biological Exposure Indices of pyrrole adducts in serum and urine are still unknown. The current study was designed to investigate the biological exposure limit of pyrrole adducts for hazard assessment of n-hexane. METHODS: Male Wistar rats were given daily dose of 500, 1000, 1500, 2000, 4000 mg/kg bw n-hexane by gavage for 24 weeks. The levels of pyrrole adducts in serum and urine were determined at 8, 24 hours postdose once a week. The Biological Exposure Indices was evaluated by neurological evaluation and the levels of pyrrole adducts. The difference in pyrrole adducts formation between humans and rats were estimated by using in vitro test. RESULTS: Dose-dependent effects were observed between the doses of n-hexane and pyrrole adducts in serum and urine, and the levels of pyrrole adduct in serum and urine approached a plateau at week 4. There was a significantly negative correlation between the time to paralysis and the level of pyrrole adducts in serum and urine, while a positive correlation between gait score and levels of pyrrole adducts in serum and urine was observed. In vitro, pyrrole adducts formed in human serum was about two times more than those in rat serum at the same level of 2,5-HD. CONCLUSION: It was concluded that the BEIs of pyrrole adducts in humans were 23.1 ± 5.91 nmol/ml in serum 8 h postdose, 11.7 ± 2.64 nmol/ml in serum 24 h postdose, 253.8 ± 36.3 nmol/ml in urine 8 h postdose and 54.6 ± 15.42 nmol/ml in urine 24 h postdose.

Correlation between levels of 2, 5-hexanedione and pyrrole adducts in tissues of rats exposure to n-hexane for 5-days.

BACKGROUND: The formation of pyrrole adducts might be responsible for peripheral nerve injury caused by n-hexane. The internal dose of pyrrole adducts would supply more information for the neurotoxicity of n-hexane. The current study was designed to investigate the tissue distributions of 2, 5-hexanedione (2,5-HD) and pyrrole adducts in rats exposed to n-hexane, and analyze the correlation between pyrrole adducts and 2,5-HD in tissues. METHODS: Male Wistar rats were given daily dose of 500,1000, 2000, 4000 mg/kg bw n-hexane by gavage for 5 days. The rats were sacrificed 24 hours after the last administration. The levels of 2, 5-hexanedione and pyrrole adducts in tissues were measured by gas chromatography and Ehrlich's reagent, respectively. The correlations between 2, 5-hexanedione and pyrrole adducts were analyzed by linear regression. RESULTS: Dose-dependent effects were observed between the dosage of n-hexane and 2, 5-hexanedione, and pyrrole adducts in tissues. The highest level of 2, 5-hexanedione was found in urine and the lowest in sciatic nerve, while the highest level of pyrrole adducts was seen in liver and the lowest in serum. There were significant correlations among the free 2, 5-hexanedione, total 2, 5-hexanedione and pyrrole adducts within the same tissues. Pyrrole adducts in serum showed the most significant correlation with free 2, 5-hexanedione or pyrrole adducts in tissues. CONCLUSION: The findings suggested that pyrrole adducts in serum might be a better indicator for the internal dose of free 2, 5-hexanedione and pyrrole adducts in tissues.

Gas-producing cellulitis from injection of spot remover fluid (n-Hexane).

BACKGROUND: Subcutaneous administration of hydrocarbons, categorized according to their toxicological profiles, is rare compared to oral, inhalational, and cutaneous routes of exposure. Furthermore, injection of n-hexane in humans has not been described. OBJECTIVES: This report demonstrates a singular case of subcutaneous administration of n-hexane. CASE REPORT: A 21-year-old man presented to the Emergency Department (ED) 7 h after injecting his left antecubital fossa with approximately 5 cc of spot remover fluid, which contained more than 95% n-hexane, in a suicide attempt. There was redness in the left forearm, but no apparent swelling was observed. He was administered tetanus prophylaxis and discharged with follow-up. However, the patient returned to the ED 14 h later, complaining of progression of the swelling around the injection site extending to the axilla. Significant volume of air in the soft tissue of the affected extremity was noted on both the radiograph and computed tomography scan; therefore, an immediate extensive incision and debridement of the diseased limb was performed. The postoperative course was uneventful, and a complete resolution of emphysema without any functional deficits was obtained for 5 months of follow-up. CONCLUSION: In patients suffering from n-hexane injection, initial physical examination findings may not be apparent. Thus, the patient must be monitored closely for evidence of a spread of subcutaneous gas with elevation and immobilization. If increase in tissue pressure or spread of gas is not prevented, as in our case, immediate incision and removal of the toxic substances should be planned.

Inhaled pan-selectin antagonist Bimosiamose attenuates airway inflammation in COPD.

Selectins, a family of cell adhesion molecules, are involved in leukocyte extravasation to sites of inflammation. We investigated the safety and efficacy of the inhaled pan-selectin antagonist Bimosiamose in patients with chronic obstructive pulmonary disease (COPD). 77 COPD patients (mean forced expiratory volume in 1 s, 57% pred.) were enrolled in a cross-over, double-blind, randomized, Placebo-controlled, multi-center trial. Bimosiamose (10 mg) or Placebo was inhaled twice daily via the breath actuated nebulizer Akita2 Apixneb™ for 28 days on top of standard bronchodilator therapy. Efficacy was assessed by measurement of inflammatory parameters in induced sputum (differential cell count, interleukin-8, matrix-metalloproteinase-9, myeloperoxidase) and lung function at day 28 of both treatment periods. The total adverse event ratio of Bimosiamose compared to Placebo treatment was balanced. Compared to Placebo, treatment with Bimosiamose led to a decrease of the interleukin-8 concentration (-9.49 ng/mL, 95%CI -18.8 to -2.7 ng/mL, p = 0.008), for the neutrophil count a difference of -0.368 × 10(6) cells/mL (95%CI -1.256 to 0.407 × 10(6)/mL, p = 0.313) was found. The macrophage count decreased by -0.200 × 10(6) cells/mL (95%CI -0.365 to -0.044 × 10(6) cells/mL, p = 0.012). Most lung function parameters showed a small numeric increase. Inhalation of Bimosiamose for 28 days was safe and well tolerated in patients with COPD. It led to an attenuation of airway inflammation (EudraCT 2009-017257-35; NCT ID: NCT01108913).

The effect of n-hexane on the gonad toxicity of female mice.

OBJECTIVE: To investigate the toxic effects of n-hexane on the Ganod of female mice. METHODS: n-Hexane was administered to four groups of mice by inhalation at doses of 0, 3.0, 15.1, and 75.8 mL/m3 respectivelyfor five weeks. Each group consisted of 10 mice, of which half were injected in first with 10 IU of pregnant mare serum gonadotrophin (PMSG) on the 33rd days, and then with 10 IU of human chorionic gonadotrophin (HCG) 48 hrs later. After the treatment, mouse sera were sampled and ovulating hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), and progesterone (P4) levels were measured by electrochemiluminescence immunoassays (ECLIA). In each group, the right ovaries of the non-super-ovulated mice were stained with hematoxylin and eosin while ovaries on the left side were prepared with the TUNEL method in order to detect apoptotic cells. RESULTS: The duration of the diestrus stage decreased significantly (P < 0.05) in the 75.8 mL/m3 group. All super-ovulated mice in each treatment group produced fewer eggs than those in the control group (P < 0.05). The number of follicles in ovaries in the 75.8 mL/m3 group was smaller compared with the control group (P < 0.05).The serum P4 levels in each treatment group were lower than those in the control group (F = 6.196, P < 0.01). The cell apoptotic rate in the 75.8 mL/m3 group was higher (P < 0.05). CONCLUSION: n-Hexane may have directly mediated via alterations hormone secretion and promoted granulosal cell apoptotic, which may be one of the important mechanisms for n-hexane induced mouse ovary impairment.

Immunomodulation property of hexane fraction of leaves of Cinnamomum tamala Linn. in rats.

The leaves of Cinnamomum tamala Linn. (CT) (Lauraceae) clinically used in Ayurveda as antidiabetic and diuretic, but no reports are available towards immunomodulating property. Its hexane fraction (CTH) was orally given to rats for 10 days and delayed type of hypersensitivity (DTH), antibody production against sheep red blood cells (SRBCs), mitotic index in bone marrow cells and concanavalin A (Con A) mediated proliferation of lymphocytes were assessed. Further on 30 days treatment, change in body weight (BW), spleen weight, thymus weight, bone marrow cellularity and hematological changes were observed. It inhibited significantly the DTH response (IC(50) 1475 +/- 57.19 mg kg(-1) BW), antibody production, suppressed mitotic index in bone marrow cells along with the suppression of lymphocyte proliferation against Con A (IC(50) 63.33 +/- 1.95 microg mL(-1)). In all experiments, cyclophasphamide and dexamethasone had been used as reference drug for in vivo and in vitro studies, respectively. On 30 days treatment, the CTH (800 mg kg(-1) BW and above) significantly suppressed growth rate, increase of spleen and thymus weight and low bone marrow cellularity. In hematological examination, it inhibited total white blood cell and lymphocytes count and increased per cent of polymorphs. Thus, it could be suggested that the fraction possesses immunosuppressive property at doses, higher than 800 mg kg(-1) BW in rats.

Solvent inhalation (toluene and n-hexane) during the brain growth spurt impairs the maturation of frontal, parietal and occipital cerebrocortical neurons in rats.

Solvent abuse during pregnancy may cause "fetal solvent syndrome", which is characterized by mild brain atrophy and associated with behavioral, cognitive, and emotional abnormalities. The present study investigated whether solvent inhalation during the preweaning period (P2-P21) alters the morphological maturation of frontal, parietal, and occipital cortical neurons. Twelve hours after delivery (postnatal day 0, P0), litters were cross-fostered, culled to 8 pups/dam and housed together with a dam in standard laboratory cages. Litters were randomly assigned to the "air-only" group (n=64, 8 litters) and to the "solvent-sniffer" group (n=72, 9 litters). During P2-P21, each animal was exposed daily to either organic solvent vapors (75% toluene and 18% n-hexane, a solvent mixture commonly found in glues and adhesives) or clean air. To determine the impact of early solvent inhalation on cortical neuronal differentiation, brains were stained using the Golgi-Cox-Sholl procedure to quantitatively assess neocortical pyramidal cell dendrogenesis. Preweaning, solvent-exposed animals displayed dramatic impairments in dendritic growth as well as significant reductions in brain weight and size.

Anthelmintic effects of Prosopis laevigata n-hexanic extract against Haemonchus contortus in artificially infected gerbils ( Meriones unguiculatus).

The anthelmintic effect of Prosopis laevigata (mezquite) n-hexanic extract was evaluated against Haemonchus contortus endoparasitic stages in artificially infected gerbils (Meriones unguiculatus). Prosopis laevigata leaves were collected from the Sierra de Huautla, Ecological Reserve of the Biosphere, in Morelos State, Mexico; dehydrated under shade and macerated with n-hexane for 3 days, followed by distillation for 8 h. This procedure was repeated three times and the final extract was kept at 4 degrees C. The in vivo effect of the plant extract was evaluated in gerbils artificially infected with H. contortus. Plant extract concentration was 40 mg/ml. Three groups of gerbils were as follows: group 1 (n = 7), P. laevigata extract at 100 microl intraperitoneally (IP); group 2 (n = 6), control--Tween 20 in water at a single dose of 100 microl IP; group 3 (n = 8) also served as a control, receiving water only, to determine the mortality due to causes other than the plant extract. An additional group of seven gerbils (group 4) was administered fenbendazole, as a positive control. Five days later the animals were euthanized and stomach and mucosa removed to quantify the nematodes. Data were analysed using the Student's t-test to compare the mean of nematodes obtained in groups 1, 2 and 3. The parasite population in the plant extract treated group 1 was reduced by 42.5% (P < 0.05) with respect to the control group 2; and when control group 3 was used for comparison the parasitic reduction was estimated as 53.11%. This study shows the in vivo anthelmintic effect of P. laevigata n-hexane extract for the first time, using gerbils as an in vivo model, with potential use in sheep.

Influence of N-hexane inhalation on the enantioselective pharmacokinetics and metabolism of verapamil in rats.

Verapamil (VER) is commercialized as a racemic mixture of the (+)-(R)-VER and (-)-(S)-VER enantiomers. VER is biotransformed into norverapamil (NOR) and other metabolites through CYP-dependent pathways. N-hexane is a solvent that can alter the metabolism of CYP-dependent drugs. The present study investigated the influence of n-hexane (nose-only inhalation exposure chamber at concentrations of 88, 176, and 352 mg/m3) on the kinetic disposition of the (+)-(R)-VER, (-)-(S)-VER, (R)-NOR and (S)-NOR in rats treated with a single dose of racemic VER (10 mg/kg). VER and NOR enantiomers in rat plasma was analyzed by LC-MS/MS (m/z = 441.3 > 165.5 for the NOR and m/z 455.3 > 165.5 for the VER enantiomers) using a Chiralpak AD column. Pharmacokinetic analysis was performed using a monocompartmental model. The pharmacokinetics of VER was enantioselective in control rats, with higher plasma proportions of the (-)-(S)-VER eutomer (AUC(0-infinity) = 250.8 vs. 120.4 ng/ml/h; P < or = 0.05, Wilcoxon test). The (S)-NOR metabolite was also found to accumulate in plasma of control animals, with an S/R AUC(0-infinity) ratio of 1.5. The pharmacokinetic parameters AUC(0-infinity), Cl/F, Vd/F, and t(1/2) obtained for VER and NOR enantiomers were not altered by nose-only exposure to n-hexane at concentrations of 88, 176, or 352 mg/m3 (P > 0.05, Kruskal-Wallis test). However, the verapamil kinetic disposition was not enantioselective for the animals exposed to n-hexane at concentrations equal to or higher than the TLV-TWA. This finding is relevant considering that the (-)-(S)-VER eutomer is 10-20 times more potent than R-(+)-VER in terms of its chronotropic effect on atrioventricular conduction in rats and humans.

The pharmacokinetics of subcutaneously injected Bimosiamose disodium in healthy male volunteers.

Bimosiamose is a novel synthetic pan-selectin antagonist developed for the treatment of acute and chronic inflammatory disorders. Therefore the pharmacokinetics of Bimosiamose disodium were studied in healthy male volunteers after single and multiple subcutaneous injections. A randomized, double-blind, placebo-controlled dose escalation trial was carried out. The subjects received subcutaneous injections of placebo or 100, 200 or 300 mg Bimosiamose disodium into the abdomen. Plasma and urine concentrations of Bimosiamose were determined. The maximum plasma concentration was 2.17+/-0.70 microg/ml and the AUC(0-infinity) 11.1+/-2.9 h microg/ml after the highest dose on day 1 (mean+/-SD). For the apparent clearance CL/f 28.7+/-7.3 l/h and the terminal half life t(1/2) 3.7+/-0.6 h were calculated. The mean residence time MRT(infinity) of 5.5 to 6.3 h for s.c. injection exceeded that after i.v. infusion due to an extended absorption time. For multiple dosing, constant pre-dose concentrations of about 20 ng/ml may be reached after two subsequent doses of 200 or 300 mg Bimosiamose disodium once daily. Almost 15% of the administered drug was excreted unchanged in urine. Moreover, Bimosiamose was well tolerated.

Targeting C-reactive protein for the treatment of cardiovascular disease.

Complement-mediated inflammation exacerbates the tissue injury of ischaemic necrosis in heart attacks and strokes, the most common causes of death in developed countries. Large infarct size increases immediate morbidity and mortality and, in survivors of the acute event, larger non-functional scars adversely affect long-term prognosis. There is thus an important unmet medical need for new cardioprotective and neuroprotective treatments. We have previously shown that human C-reactive protein (CRP), the classical acute-phase protein that binds to ligands exposed in damaged tissue and then activates complement, increases myocardial and cerebral infarct size in rats subjected to coronary or cerebral artery ligation, respectively. Rat CRP does not activate rat complement, whereas human CRP activates both rat and human complement. Administration of human CRP to rats is thus an excellent model for the actions of endogenous human CRP. Here we report the design, synthesis and efficacy of 1,6-bis(phosphocholine)-hexane as a specific small-molecule inhibitor of CRP. Five molecules of this palindromic compound are bound by two pentameric CRP molecules, crosslinking and occluding the ligand-binding B-face of CRP and blocking its functions. Administration of 1,6-bis(phosphocholine)-hexane to rats undergoing acute myocardial infarction abrogated the increase in infarct size and cardiac dysfunction produced by injection of human CRP. Therapeutic inhibition of CRP is thus a promising new approach to cardioprotection in acute myocardial infarction, and may also provide neuroprotection in stroke. Potential wider applications include other inflammatory, infective and tissue-damaging conditions characterized by increased CRP production, in which binding of CRP to exposed ligands in damaged cells may lead to complement-mediated exacerbation of tissue injury.

Bimosiamose, an inhaled small-molecule pan-selectin antagonist, attenuates late asthmatic reactions following allergen challenge in mild asthmatics: a randomized, double-blind, placebo-controlled clinical cross-over-trial.

BACKGROUND: Asthma is characterized by increased recruitment of inflammatory cells from the circulation into the airways. As selectins mediate tethering and rolling of leukocytes on the vascular endothelium, they constitute a promising target for the therapeutic modulation of inflammation. We evaluated the effect of inhaled bimosiamose (TBC1269), a synthetic pan-selectin antagonist, on allergen-induced late asthmatic reactions (LAR) in mild asthmatics. METHODS: Twelve male subjects with mild allergic asthma (only beta-agonists prn) with demonstrable LAR (fall of FEV1 3-8h after allergen inhalation >15% of baseline) at screening completed a randomized, double-blind, placebo-controlled clinical cross-over-trial. Subjects were treated with inhaled bimosiamose 70 mg bid or matching placebo on days 1-3 and 70 mg once on the morning of day 4. On day 4 following the last inhalation of study drug, an allergen challenge was performed. The primary endpoint was the maximum fall in FEV1 between 3 and 8h after allergen inhalation on active treatment vs. placebo. Secondary endpoints included early asthmatic response, exhaled nitric oxide, and airway hyperresponsiveness to methacholine 24h post allergen. RESULTS: Bimosiamose significantly attenuated the maximum LAR compared to placebo by 50.2% (placebo mean+/-SEM fall -13.10+/-2.30%, bimosiamose -6.52+/-3.86%, treatment effect p=0.045; linear mixed-effects model). There was no effect of active treatment on early asthmatic response, post allergen airway hyperresponsiveness or exhaled nitric oxide, and peripheral blood cells. CONCLUSIONS: Administration of the pan-selectin antagonist bimosiamose is effective in a human allergen challenge model of asthma. The result of this proof-of-concept exploratory trial is the first study that demonstrates clinical efficacy of selectin-antagonists as novel therapeutic strategy in asthma.

Short-term oral toxicity of pentyl ether, 1,4-diethoxybutane, and 1,6-dimethoxyhexane in male rats.

Pentyl ether (PE) and two newly synthesized polyoxy ethers, 1,4-diethoxybutane (DEB) and 1,6-dimethoxyhexane (DMH), have been proposed as candidate diesel fuel additives. To characterize and compare their toxicity and to provide information for risk assessment, a 4-week oral study was conducted on these compounds. Male Sprague-Dawley rats (288 +/- 20 g) were divided into groups of seven animals each, and were administered by gavage low (2 mg/kg body weight), medium (20 mg/kg body weight), or high (200 mg/kg body weight) doses of PE, DEB, or DMH, respectively, 5 days/week for 4 weeks. Animals in the control group received the vehicle (corn oil, 1 ml/100 g body weight) only. At the end of the exposure period, relative testis and thymus weights were reduced by 30 and 46%, respectively, in animals treated with the high dose of DMH. Significant reductions in serum lactate dehydrogenase (LDH), serum uric acid, and blood platelet counts were also observed in the high dose of DMH. Serum corticosterone was significantly depressed in the high doses of PE and DEB and in the low dose of DMH. Serum thiobarbituric acid-reactive substances (TBARS) were decreased (p < 0.05) in all DMH treatment groups and in the medium and high dose PE and DEB groups, while liver TBARS were unaffected by treatment. In the liver, increased glutathione (GSH) level and glutathione-S-transferases activity were detected in the high dose DMH group. Urinary ascorbic acid levels were markedly increased in animals receiving the high doses of PE, DEB, and DMH. Urinary formic acid was increased by 13 times in the high dose PE and DEB groups. Testes of all animals receiving the high dose of DMH showed a moderate to marked degree of degeneration of the seminiferous tubules, including a mild degree of vacuolation. At the same time, the epididymis of these animals had substantially reduced sperm density with prominent presence of spermatid giant cells. Mild histological changes were seen in the liver at all dose levels for all three chemicals. Thyroid effects were also observed in the high dose PE and DEB groups and in the medium and high dose DMH groups. It was concluded that DMH is the most toxic of the three ethers tested, with testicular, epidiymal, and thymic effects being the most prominent at 200 mg/kg. Other significant changes included depressed platelet counts and serum biochemical changes. Increased production of formic acid, an ocular toxin, from PE and DEB treatments may also be of toxicological concern.

Evaluation of 2,5-hexanedione in urine of workers exposed to n-hexane in Brazilian shoe factories.

Urinary 2,5-hexanedione (2,5-HD) is used as a biomarker for biological monitoring of workers exposed to n-hexane. The purpose of this study was to compare two types of treatment of urine samples during clean-up (with and without acidic hydrolysis) and to study the exposure situation of workers exposed to n-hexane during shoe manufacturing. There, various glues containing n-hexane are used. Quantification of 2,5-HD was carried out by gas chromatography and flame ionization detection (GC-FID). Fifty-two urine samples taken from workers of seven shoe factories were analyzed. Thirty-four persons from the administrative staff of the same factories served as controls. They were not known to be exposed to n-hexane. The samples treated with acidic hydrolysis showed levels (average 0.94 mg/l) approximately 10 times higher than samples without acidic hydrolysis (0.09 mg/l). The difference is predominantly caused by the conversion of other metabolites of n-hexane (e.g. 4,5-dihydroxy-2-hexanone) to 2,5-HD in the presence of acids. Our results also show, that exposure to n-hexane is different between various industries. Levels of 2,5-HD in urine are predominantly dependent on the type of operation (how the glue is applied on the leather during shoe manufacturing). Simple measures, e.g. using a glue handgun instead of a paintbrush significantly decreased exposure to n-hexane.

Urinary 2,5 hexanedione as a biomarker of n-hexane exposure.

n-Hexane is a saturated aliphatic hydrocarbon widely used in industry. In most cases it is used as a mixture with hexane isomers and various others solvents in the form of commercial hexane. n-Hexane is metabolized oxidatively to a number of compounds, including 2,5-hexanedione (2,5-HD), which is eliminated through the urine and is implicated in the neurotoxic effect of this solvent. The main objective of this study was to evaluate urinary 2,5-HD as a biomarker of n-hexane exposure. The study was carried out in seven industrial units. Post-shift urine samples from 111 workers who handled commercial hexane were collected and analysed for 2,5-HD by capillary gas chromatography. Air sampling was performed in the breathing zones of the workers, and the air samples were analysed using validated methods. Monitoring individual exposures showed that n-hexane exposure varied from 5 to 70 p.p.m. (mean +/- SD = 15.24 +/- 2.98 p.p.m.). Significant correlation was observed between exposure to n-hexane and urinary 2,5-HD levels, with high correlation coefficients (rho = 0.81, p = 0.000), suggesting that urinary 2,5-HD is a good biomarker of occupational exposure to n-hexane. Urinary 2,5-HD is recommended as a better tool than air monitoring in the assessment of health risk, namely the early detection of n-hexane neurotoxicity.

Glue solvent inhalation impairs host resistance to Mycobacterium bovis-induced infection in hamsters.

Industrial organic solvents present in glue are among the common used psychotropic drugs in Brazil and perhaps worldwide; but few data are available concerning the toxic effects of glue sniffing, with almost no information about immunotoxicity. This seems interesting because several drugs and environmental chemicals are recognized as potential immunotoxicants. The present study investigated the effects of forced inhalation of a toluene/n-hexane 1:1 mixture on hamster resistance to Mycobacterium bovis. Adult hamsters were divided at random into 3 equal groups. Animals of Groups E and E inhaled the mixture of toluene/n-hexane twice daily for 37 d. Group C was placed for the same period of time in identical chambers free of solvents. Two days after the beginning of the experiment, Groups E and C were injected ip with 0.5 ml of an activated suspension of M. bovis; Group E received the same volume of a control solution. Hamsters inhaling the toluene/n-hexane mixture (E) exhibited increased weight loss, increased scores of M. bovis colony forming units isolated from liver, lung and spleen, increased granulomatous areas in the liver, lung and spleen. Inhalation of the toluene/n-hexane mixture for 37 d also increased serum cortisol compared to control hamsters. Tuberculosis is an infection with an intracellular bacterium in which sensitivity is determined mainly by host response. The present data demonstrated impaired defense against M. bovis in hamsters inhaling a toluene/n-hexane mixture for 37 d. Since macrophages are the architectural and functional units of the granulomas in tuberculosis, and no data were found about glue solvent effects on cellular immunity, the present data suggest an indirect effect of glue solvents on macrophage/lymphocyte activity via stress induction and central nervous system stimulation of hormonal (ACTH/cortisol) secretion and/or autonomic nervous system activity.

Functional Cyp2e1 is required for substantial in vivo formation of 2,5-hexanedione from n-hexane in the mouse.

Neurotoxicity of n-hexane is mediated by its metabolite 2,5-hexanedione (2,5-HD). Cytochrome P4502E1 (CYP2E1) has been suggested but not shown to be involved in the formation of the metabolite. An objective of the current study was to assess the essentiality of CYP2E1 for in vivo 2,5-HD formation from n-hexane. This was accomplished by comparing urinary levels of the gamma-diketone in n-hexane-treated mice in which the Cyp2e1 gene has been deleted (Cyp2e1-/-) with that in n-hexane-treated wild-type (Cyp2e1+/+) mice. 2,5-HD was detectable not as the free compound but as further metabolites, at levels that were comparable in both strains of mice, following a daily 200 mg/kg i.p. dose of the alkane for 10 days. Continued daily n-hexane treatment resulted in increased urinary levels of 2,5-HD metabolites in Cyp2e1+/+ but not in Cyp2e1-/- mice. Only in Cyp2e1+/+ mice and only on day 21 of n-hexane treatment was a trace level of unchanged 2,5-HD detected. 3-Hexanol was the only other n-hexane metabolite detected in the mice but its concentration was higher in Cyp2e1-/- than in Cyp2e1+/+ mice. In n-hexane-treated rats, in contrast to mice, multiple metabolites of the alkane, including unchanged 2,5-HD, were detected. The results indicate that substantial in vivo formation of 2,5-HD from n-hexane in the mouse requires CYP2E1, and suggest that further detoxification of the metabolite may be very efficient in this species.

Chronic inhalation carcinogenicity study of commercial hexane solvent in F-344 rats and B6C3F1 mice.

The carcinogenic and chronic toxicity potential of commercial hexane solvent was evaluated in F-344 rats and B6C3F1 mice (50/sex/concentration/species) exposed by inhalation for 6 h/day, 5 days/week for 2 years. Target hexane vapor concentrations were 0, 900, 3000, and 9000 ppm. There were no significant differences in survivorship between control and hexane-exposed groups, and clinical observations were generally unremarkable. Small, but statistically significant decreases in body weight gain were seen in rats of both sexes in the mid- and high-exposure groups and in high-expsoure female mice. The only noteworthy histopathological finding in rats was epithelial cell hyperplasia in the nasoturbinates and larynx of exposed groups. This response was judged to be indicative of upper respiratory tract tissue irritation. No significant differences in tumor incidence between control and hexane-exposed rats were found. In mice, uterine tissue from the high-exposure females exhibited a significant decrease in the severity of cystic endometrial hyperplasia compared to controls. An increase in the combined incidence of hepatocellular adenomas and carcinomas was observed in high-exposure female mice. The incidence of liver tumors was not increased in the mid- or low-exposure female mice or in male mice exposed to hexane. An increased incidence of pituitary adenomas was observed in female, but not male mice. This finding was not believed to have been treatment-related because the incidence in the control group was unusually low, and the incidence in exposed groups was not dose-related and was within the historical control range. No other neoplastic changes judged to be treatment-related were observed in tissues from male or female mice. In conclusion, chronic exposure to commercial hexane solvent at concentrations up to 9000 ppm was not carcinogenic to F-344 rats or to male B6C3F1 mice, but did result in an increased incidence of liver tumors in female mice.

Focal conduction block in n-hexane polyneuropathy.

A 19-year-old man with an asymptomatic history of recreational gasoline vapor inhalation presented with subacute progressive quadriparesis. For 2 weeks, he had intensely inhaled Coleman fuel oil vapor, which contains n-hexane. Nerve conduction studies including near-nerve needle stimulation showed focal conduction block in the bilateral median and ulnar nerves. Sural nerve biopsy was consistent with giant axonal neuropathy. Conduction block as seen in this case has not heretofore been described in n-hexane polyneuropathy.