Naphthalene Treatment Research Articles

Use of White Rot Fungus Pleurotus ostreatus as a Biodegradator of Naphthalene in Contaminated Soil

The capacity of white rot fungus, Pleurotus ostreatus, to biodegrade naphthalene present in sandy-clay-loam soil samples at concentrations of 50, 100, 200, and 500 mg/L was investigated experimentally. Using high-pressure liquid chromatography (HPLC), triplicate samples of liquid extracts from both fungus-inoculated and control (noninoculated) soil samples were taken at time periods of 0, 30, 60, and 90 days for determination of residual naphthalene concentrations. Relevant factors (naphthalene concentration, treatment duration, and residual naphthalene concentration) and their interaction were compared for both inoculated and control samples, using pair plots and level of significance. Overall, samples inoculated with P. ostreatus had reduced naphthalene concentrations to 1–40% of initial concentrations for the 90-day sampling period, compared with 63–82% for control treatments. In the control soil samples, extractable naphthalene increased by approximately 2–5% of initial content between 60 and 90 days...

Optimization of Targeted Cell Replacement Therapy: A New Approach for Lung Disease

Cell replacement therapy is a promising approach for treatment of lung disease such as cystic fibrosis, although rates of engraftment need to be improved. We previously showed improved cell retention in the lung using transtracheal delivery compared to intravenous injection. Here, we optimized other parameters of cell delivery using 7-day cultured bone marrow cells (BMCs). Retention of BMC in the lung was dose-dependent. Naphthalene treatment had maximal effects on BMC retention when given 2 days before cell delivery. Naphthalene treatment of the donor amplified a CCSP(+) population and increased retention efficiency in the recipient. Repeated naphthalene treatment and repeated cell delivery both resulted in greater retention. The contribution of the second cell dose was minimal suggesting that a second delivery of BMC promotes proliferation of the first. Busulfan-induced myelosuppression augmented retention of exogenous BMC by up to 20-fold. These BMC helped CCSP reconstitution. Using the optimal delivery techniques and cytokeratin-18-driven green fluorescent protein (GFP) reporter mice, we detected threefold more GFP suggesting more BMC differentiated to epithelial cells. We propose that improved engraftment in the lung will increase cell replacement and thus be a more efficient therapeutic approach for various lung diseases.

Genetic Modification of Airway Progenitors after Lentiviral Gene Delivery to the Amniotic Fluid of Murine Fetuses

Lentiviral vectors with the firefly luciferase or enhanced green fluorescent protein (EGFP) transgenes were delivered to the amniotic fluid of murine fetuses at Embryonic Day (E) 14.5 or E16.5. Whole-body imaging of luciferase recipients after birth demonstrated transgene expression in the peritoneal and thoracic regions. Organ imaging showed luciferase expression in lung, skin, stomach, and/or intestine. Histological immunofluorescence analysis of EGFP recipients demonstrated that small clusters (≤ three cells) of EGFP-positive epithelial cells were present in the large and small airways of recipients at up to 7 months (n = 11). There was no difference in the frequency of transgene expression in mice injected at E14.5 or E16.5 in respiratory or nonrespiratory organs. Analysis of the bronchoalveolar duct junctions on tissue sections of recipient mice identified multiple EGFP-positive epithelial cells. Cells coexpressing EGFP, Clara cell 10-kd protein, and surfactant protein C (SPC) were also found in lungs, consistent with the transduction of bronchoalveolar stem cells. Next, naphthalene lung injury in both luciferase and EGFP recipients was performed to determine whether transduced cells could contribute to tissue repair. In luciferase recipients, the whole-body luciferase signal increased 2- to 20-fold at 2 weeks after naphthalene treatment. Remarkably, immunohistological analysis of the lungs of EGFP recipients after lung injury repair demonstrated repopulation of airways with long stretches of EGFP-positive epithelial cells (n = 4). Collectively, these data demonstrate that lentiviral gene delivery to the amniotic fluid of murine fetuses genetically modifies long-lived epithelial progenitors capable of contributing to lung injury repair.

Role of E74‐like transcription factor‐3 in the pulmonary regenerative response to naphthalene‐induced bronchiolar epithelial injury

E74‐like transcription factor‐3 (Elf‐3), a member of the ETS transcription factor family, is strongly expressed in epithelial‐rich tissues, such as the developing lung and small intestine. Although previous studies have shown a defect in the terminal differentiation of the small intestinal epithelium of Elf‐3‐deficient mice during embryonic development, very little is known about the role Elf‐3 may play in the repair of the lung epithelium after injury. In order to elucidate an involvement of Elf‐3 in regeneration of the bronchiolar epithelium after Clara cell‐specific injury, we administered naphthalene to both wild type (Elf‐3 +/+) and Elf‐3‐deficient (Elf‐3 −/−) mice. Histopathological analysis revealed no significant difference in the extent of naphthalene‐induced Clara cell injury between Elf‐3 +/+ mice and Elf‐3 −/− mice. We found that the kinetics of cell proliferation and mitosis in the distal bronchiolar airway epithelium as well as Clara cell reconstitution was delayed in Elf‐3 −/− mice as compared to Elf‐3 +/+ mice; however, cell proliferation and mitosis in the peribronchiolar interstitium of Elf‐3 −/− mice was significantly greater than that of Elf‐3 +/+ mice after naphthalene treatment. Taken together, our results suggest that Elf‐3 plays an important role in the regulation of lung cell proliferation and differentiation during repair of the injured bronchiolar epithelium.

Protective effect of erdosteine against naphthalene-induced oxidative stress in rats

ABSTRACT: In this study the role of free radicals in naphthalene-induced toxicity and the protection by erdosteine are investigated. Female Sprague-Dawley rats were treated with a single oral dose of 1100 mg naphthalene/kg in corn oil. Erdosteine was given 50 mg/kg/day orally for 3 days before naphthalene treatment and rats were decapitated 24 hours after naphthalene administration. Liver and kidney tissue samples were taken for determination of malondialdehyde (MDA), glutathione (GSH), Na+, K+-ATPase and myeloperoxidase (MPO) activities. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN) and creatinine levels and lactate dehydrogenase (LDH) activity were measured in the serum samples, while TNF-

In vitro toxicity of naphthalene, 1-naphthol, 2-naphthol and 1,4-naphthoquinone on human CFU-GM from female and male cord blood donors

In animal models, naphthalene toxicity has been studied in different target organs and has been shown to be gender-dependent and metabolism related. In humans, it is readily absorbed and is metabolised by several cytochrome P450's. Naphthalene and its metabolites can cross the placental barrier and consequently may affect foetal tissues. The aim of this study was to compare the in vitro toxicity of naphthalene and its metabolites, 1-naphthol, 2-naphthol and 1,4-naphthoquinone, on human haematopoietic foetal progenitors (CFU-GM) derived from newborn male and female donors. The mRNA expression of Cyp1A2 and Cyp3A4 was also evaluated. Naphthalene did not affect CFU-GM proliferation, while 1-naphthol, 2-naphthol and particularly 1,4-naphthoquinone strongly inhibited the clonogenicity of progenitors, from both male and female donors. mRNA of Cyp1A2 and Cyp3A4 was not expressed neither at the basal level, nor after naphthalene treatment, while treatment with 1,4-naphthoquinone induced expression of both enzymes in both genders, with Cyp1A2 being expressed four times more than Cyp3A4. Female CFU-GM was significantly more sensitive to 1,4-naphthoquinone than male and after treatment both enzymes were expressed twice as much as in the male precursors. These results suggest that a gender-specific 1,4-naphthoquinone metabolic pathway may exist, which gives rise to unknown toxic metabolites.

Fabrication and characterization of self-assembled Nafion–SiO 2–ePTFE composite membrane of PEM fuel cell

Self-assembled Nafion–SiO 2 polymer electrolyte membrane enhanced by ePTFE matrix was prepared in this study. The original ePTFE membrane was chemically modified before the preparation by sodium–naphthalene treatment to increase the wetting compatibility between self-assembled Nafion–SiO 2 dispersions and ePTFE matrix. Compared to the freestanding Nafion–SiO 2 membrane, the physical strength of the as-resulting ePTFE PEM was significantly improved from ∼20 MPa to 32 MPa. The area conductance of the as-resulting membrane was also promoted to ∼40 S cm −2 and ∼50 S cm −2, respectively at 60 °C and 100 °C with the decrease of the membrane thickness (15 μm) in 50% RH gas atmosphere. With the presence of self-assembled silica particles, the self-assembled Nafion–SiO 2–ePTFE composite membrane possesses excellent water-retention property. At elevated operating temperature of 100 °C, 50% RH, 0 back pressure, the output voltage of the Nafion–SiO 2–ePTFE fuel cell was 0.603 V under condition of 600 mA cm −2, 0.105 V higher than that of the freestanding Nafion/ePTFE fuel cell under the same condition.

Naphthalene disrupts pheromone induced mate search in the amphipod Corophium volutator (Pallas)

Many crustaceans communicate with pheromones during mating. In the infaunal amphipod Corophium volutator (Pallas), females release gender-specific waterborne pheromones that guide males in their search for receptive burrowed females. Pollutants that affect the pheromone release or impair the ability of males to detect and respond to chemosensory cues, could profoundly affect mating. C. volutator is commonly found on shallow soft sediments in estuaries and coastal waters, and their reproductive season coincides with intense traffic of leisure boats, which discharge high concentrations of fuel into the water and sediment of these areas. This study shows that sublethal exposure to naphthalene, a polycyclic aromatic hydrocarbon abundant in motor fuel, disturbs chemical communication in C. volutator. This was demonstrated in Y-maze bioassays, where males were allowed to follow female pheromones after separately exposing the males or females to naphthalene spiked sediments (0, 0.5, 5 or 50 μg g −1 dw, nominal concentrations) for 3 days. The results show that exposure to naphthalene at the two lower concentrations significantly affects the males’ response to female pheromones ( p < 0.05 and p < 0.01, respectively). Male search activity was reduced by 27–45% and males could no longer find females by the use of the olfactory sense. Analysed sediment samples, however, indicate that the naphthalene concentrations causing this effect were 2–20 times lower than nominal concentrations. At the highest naphthalene treatment, no significant difference from the controls was found, probably explained by a different exposure regime for these amphipods since they seemingly avoided burrowing in sediments. Female C. volutator produce and release pheromones, despite naphthalene exposure. Disrupted chemical communication in C. volutator may affect the reproductive fitness of males and females with possible consequences for populations in contaminated areas.

Fabrication and characterization of PFSI/ePTFE composite proton exchange membranes of polymer electrolyte fuel cells

PFSI/ePTFE composite proton exchange membranes were fabricated by impregnating perfluorosulfonic acid resin (PFSI resin, Nafion) into chemically modified expanded PTFE (ePTFE) matrix. Chemical modification of sodium–naphthalene treatment and N-methylol acrylamide (NMA) grafting decreased the contact angle of the as-received ePTFE from 125 ± 0.5° to 67 ± 0.5°, effectively converting the as-received hydrophobic ePTFE to a hydrophilic ePTFE matrix. The composite membrane fabricated with the hydrophilic ePTFE have higher impregnated PFSI loading, much lower porosity and better PTFE/PFSI interface contact, as compared to the composite membranes with the as-received ePTFE. This leads to much lower gas permeability and significantly improves the durability under an accelerated dry/wet cycle test. The fuel cell made from the PFSI/ePTFE composite membranes with hydrophilic ePTFE showed superior performance as compared to that with the composite membrane made from the as-received ePTFE and Nafion 211 membrane.

Interactive effects of naphthalene treatment and the onset of vitellogenesis on energy metabolism in liver and gonad, and plasma steroid hormones of rainbow trout Oncorhynchus mykiss

The purpose of the study was to assess in female fish the possible interaction between treatment with a polycyclic aromatic hydrocarbon (PAH) like naphthalene and the onset of vitellogenesis. In a first experiment, female rainbow trout ( Oncorhynchus mykiss) at stages 2–3 (previtellogenesis) or 4 (early vitellogenesis) were intraperitoneally injected (2 μl g − 1 ) with vegetable oil alone (control) or containing naphthalene (50 mg kg − 1 ) to be sampled 3 h later. A second experiment was similarly designed but using fish intraperitoneally implanted (10 μl g − 1 ) with slow-release coconut oil implants alone (control) or containing 50 mg naphthalene kg − 1 body mass that were sampled 3 days after injection. On each sampling time, plasma levels of cortisol and 17β-estradiol, and several metabolic parameters in plasma, liver and gonad were assessed. In controls, early vitellogenic fish compared with previtellogenic fish displayed changes that in some cases are confirmatory of previous studies whereas in other cases provide new information in plasma (increased amino acid levels), liver (decreased capacity for exporting glucose and reduced amino acid levels) and gonad (decreased amino acid levels). Naphthalene treatment produced in previtellogenic fish decreased 17β-estradiol levels in plasma, increased plasma glucose or decreased liver gluconeogenic capacity whereas no major effects were noticed on parameters involved in lipid, amino acid and lactate metabolism. Differential effects of naphthalene treatment were noticed in early vitellogenic fish such as decreased 17β-estradiol and glucose levels in plasma, increased hexokinase and glucokinase and lack of changes in fructose 1,6-bisphosphatase activities in liver, and a lower decrease of amino acid levels in gonad. Those alterations produced by naphthalene treatment resulted in a decreased capacity for covering the energy demand of vitellogenesis in liver and gonad that could contribute to a delay and/or impairment of the onset of maturation.

Plant litter decomposition influenced by soil animals and disturbance in a subtropical rainforest of Taiwan

Soil fauna has been postulated as one of the paramount determinants of decomposition in the humid tropics. However, its effect on litter decomposition has only been demonstrated in few forest sites in Central America. In addition, landslide is a common disturbance associated with heavy rainfall brought by tropical cyclones in the tropics and can potentially alter abundance and structure of soil animals and thus affect litter decomposition. In this study, we examined the effect of soil animals on litter decomposition in an Asian subtropical monsoon forest and compared the animal effects in landslide-disturbed (2 years old) and undisturbed sites. Animal exclusion by naphthalene treatment significantly reduced the density and diversity of litterbag animals and slowed down the rate of decomposition in both landslide-disturbed and undisturbed sites. However, density (per unit area) and diversity of the litter animals and litter decomposition rate did not differ between the landslide-disturbed and undisturbed sites for both control and animal-excluded treatments. Our data suggest that the abundance of soil animals is not limited by litter mass. Furthermore, soil fauna recover quickly from landslides, and fauna's facilitative effect on litter decomposition is not altered after their recovery.

Consequences of Abrupt Glutathione Depletion in Murine Clara Cells: Ultrastructural and Biochemical Investigations into the Role of Glutathione Loss in Naphthalene Cytotoxicity

Glutathione plays many critical roles within the cell, including offering protection from reactive chemicals. The bioactivated toxicant naphthalene forms chemically reactive intermediates that can deplete glutathione and covalently bind to cellular proteins. Naphthalene selectively injures the nonciliated epithelial cells of the intrapulmonary airways (i.e., Clara cells). This study attempted to define what role glutathione loss plays in naphthalene cytotoxicity by comparing Swiss-Webster mice treated with naphthalene with those treated with the glutathione depletor diethylmaleate. High-resolution imaging techniques were used to evaluate acute changes in Clara cell ultrastructure, membrane permeability, and cytoskeleton structure. A single dose of either diethylmaleate (1000 mg/kg) or naphthalene (200 mg/kg) caused similar glutathione losses in intrapulmonary airways (< 20% of control). Diethylmaleate did not increase membrane permeability, disrupt mitochondria, or lead to cell death--hallmark features of naphthalene cytotoxicity. However, diethylmaleate treatment did cause Clara cell swelling, plasma membrane blebs, and actin cytoskeleton disruptions similar to naphthalene treatment. Structural changes in mitochondria and Golgi bodies also were noted. Changes in ATP levels were measured as an indication of overall cell function, in isolated airway explants incubated with diethylmaleate, naphthalene, or naphthalene metabolites in vitro. Only the reactive metabolites of naphthalene caused significant ATP losses. Unlike the lethal injury caused by naphthalene, the disruptive cellular changes associated with glutathione loss from diethylmaleate seemed to be reversible after recovery of glutathione levels. This suggests that glutathione depletion may be responsible for some aspects of naphthalene cytotoxicity, but it is not sufficient to cause cell death without further stresses.

Lewis Acid-Mediated Carboxylation of Fused Aromatic Compounds with Carbon Dioxide

Abstract Direct and regioselective carboxylation of fused aromatic compounds with carbon dioxide is achieved with the aid of a Lewis acid. Thus, treatment of naphthalene, anthracene, and phenanthrene with carbon dioxide (3.0 MPa) in benzene at 40 °C in the presence of AlBr3 gave 1-naphthoic acid, 9-anthracenecarboxylic acid, and 9-phenanthrenecarboxylic acid as the sole acid product in 43, 20, and 34% yields, respectively.

Prior exposure to aged and diluted sidestream cigarette smoke impairs bronchiolar injury and repair.

The bronchiolar injury/repair response to naphthalene (NA) in mice includes acute distal airway epithelial injury that is followed by epithelial proliferation and redifferentiation, which result in repair of the epithelium within 14 days. To test whether prior exposure to aged and diluted sidestream cigarette smoke (TS) would alter the injury/repair response of the airway epithelium, adult mice were exposed to either filtered air (FA) or smoke for 5 days before injection with either corn oil carrier (CO) or naphthalene. Mice were killed 1 and 14 days after naphthalene injury. Lung and lobar bronchus were examined and measured using high-resolution epoxyresin sections. The control group (FACOFA) that was exposed to filtered air/corn oil/filtered air contained airway epithelium similar to untreated controls at all airway levels. The group exposed to tobacco smoke/corn oil/filtered air (TSCOFA) contained some rounded cells in the small airways and some expansion of the lateral intercellular space in the larger airways. Necrotic or vacuolated cells were not observed. As expected, the epithelium in the group exposed to filtered air/naphthalene/filtered air (FANAFA) contained many light-staining vacuolated Clara cells and squamated ciliated cells within distal bronchioles during the acute injury phase. Repair (including redifferentiation of epithelial cells and restoration of epithelial thickness) was nearly complete 14 days after injury. The extent of Clara cell injury, as assessed in lobar bronchi, was not different between the four groups. Although the FANAFA group contained greater initial injury in the distal airways at 1 day, the group exposed to tobacco smoke/naphthalene/filtered air (TSNAFA) had the least amount of epithelial repair at 14 days after naphthalene treatment; many terminal bronchioles contained abundant squamated undifferentiated epithelium. We conclude that tobacco smoke exposure prior to injury (1) does not change the target site or target cell type of naphthalene injury, since Clara cells in terminal bronchioles are still selectively injured; (2) results in slightly diminished acute injury from naphthalene in distal bronchioles; and (3) delays bronchiolar epithelial repair.

Cytotoxicity of 1,2-epoxynaphthalene is correlated with protein binding and in situ glutathione depletion in cytochrome P4501A1 expressing Sf-21 cells.

Naphthalene is metabolized by several cytochrome P-450 (CYP) monooxygenases to 1,2-epoxynaphthalene. However, the subsequent interactions of the epoxide with macromolecules in the cells, and the significance of these interactions to cellular injury, are not well characterized. Additionally, CYP1A1, which can metabolize naphthalene to 1,2-epoxynaphthalene, may be induced by a number of xenobiotics. Yet, the in situ interaction between naphthalene and CYP1A1 alone, without the influence of other xenobiotic metabolizing enzymes, has not been examined. Using a model eukaryotic expression system capable of over-expressing recombinant CYP1A1, we found that naphthalene was toxic to cells expressing CYP1A1 in a dose- (LC50: 0.3 mM) and time-dependent (LT50: 12 h) manner. Naphthalene treatment of CYP1A1-expressing cells resulted in a 47% decrease in cellular glutathione (GSH) levels. Pretreatment with ethyl ester GSH, a GSH analog, protected CYP1A1-expressing cells such that viability was 30% greater than for cells treated with naphthalene alone. Cytotoxicity was strongly correlated (r2: 0.96) with covalent binding of cellular proteins. Alkaline permethylation techniques showed that cysteinyl-SH groups of cellular proteins are a nucleophilic target of the epoxide metabolite. These results suggest that, in the absence of other pathways, naphthalene is modified by CYP1A1 to 1,2-epoxynaphthalene, which subsequently binds cellular sulfhydryl groups on proteins and GSH.

Alteration of Pulmonary Neuroendocrine Cells during Epithelial Repair of Naphthalene-Induced Airway Injury

Whole-mount airway preparations isolated from the lungs of mice treated by intraperitoneal injection of naphthalene and allowed to recover for 5 days were examined for the distribution and abundance of solitary pulmonary neuroendocrine cells (PNECs) and neuroepithelial bodies (NEBs) along the main axial pathway of the right middle lobe. Sham mice treated with corn oil vehicle were examined in a similar manner. An antibody to calcitonin gene-related peptide, a neuroendocrine cell marker, was used to identify the location, size, and number of PNECs and NEBs in the airways. After naphthalene treatment and epithelial repair, NEBs were significantly increased along the walls of the airways as well as on branch point ridges. The surface area covered by NEBs composed of 20 or fewer PNECs was significantly enlarged after naphthalene treatment compared with control NEBs of an equivalent cell number. The PNEC number per square millimeter was also increased more than threefold above control values after naphthalene treatment. These findings provide further support for a key role of neuroendocrine cells in the reparative process of airway epithelial cell renewal after injury.

Effect of vitamin E eye drops on naphthalene-induced cataract in rats.

The effect of vitamin E acetate (VEA) eye drops on naphthalene-induced cataract in rats was investigated by Scheimpflug image analysis. The control group was administered only naphthalene (1 g/kg), while the other group was additionally given 1% VEA eye drops into both eyes 5 times a day every day for 9 weeks from the start of naphthalene treatment. During those 9 weeks, the changes of the crystalline lens were documented by an anterior eye segment analysis system (EAS-1000, NIDEK) once a week in mydriasis (Mydrin-P, Santen Pharmaceutical Co., Ltd.). The characteristic density values of the anterior deeper cortex regions were measured. The light scattering intensity of lenses from VEA eye drop-treated animals was significantly lower than that of animals without VEA treatment. This difference was found 1 week, 4 weeks, and from 7 to 9 weeks after the start of naphthalene application. VEA eye drops may have the potential to delay the progression of naphthalene-induced cataract in rats.

Early events in naphthalene-induced acute Clara cell toxicity: comparison of membrane permeability and ultrastructure.

Naphthalene causes severe dose- and site-selective injury to mouse nonciliated bronchiolar (Clara) epithelial cells. Toxicity is characterized by exfoliation of injured Clara cells into the airway lumen 24 h after exposure. The purpose of this study was to define the temporal pattern of intracellular changes immediately following naphthalene treatment, with the goal of identifying critical early events involved in cytotoxicity. Mice were injected with naphthalene or carrier and were killed 1, 2, 3, and 6 h after treatment (PT). Loss of membrane integrity was assessed by ethidium homodimer-1 permeability and confocal microscopy. Cell morphology and ultrastructure were evaluated using high-resolution light and electron microscopy. Permeable cells were found only in terminal bronchioles and increased in abundance with time PT. At 2 and 3 h PT, when most Clara cells had early signs of injury, few permeable cells were detected. Many Clara cells had apical membrane blebs that contained abundant, swollen, smooth endoplasmic reticulum (SER) and few other organelles. By 6 h PT many Clara cells were membrane-permeable. However, many permeable Clara cells lacked apical blebs and SER was less abundant in these cells. Cytoplasmic blebbing may be a mechanism to protect the cell by isolating and removing damaged SER. We conclude that the early stages of injury include SER swelling and bleb formation which precede increases in cell membrane permeability after acute naphthalene injury to bronchiolar Clara cells in vivo.

Naphthalene-induced cataract model in rats: A comparative study between slit and retroillumination images, biochemical changes and naphthalene dose and duration

PURPOSE. The purpose of the study was to compare different methods of photographic evaluation of cataract formation in rats in response to different regimes of naphthalene treatment. Furthermore, we intended to study the relationship between cataract extension and biochemical parameters. METHODS. Brown Norway rats were treated with 0.10–1.5 g naphthalene/kg body weight, twice a week for ten weeks to induce cataract or placebo. Slit illumination and retroillumination (SI and RI) photographs were produced by an EAS-1000 instrument to document cataract formation as light-scattering intensity. The degree of the cataractous changes was quantified in SI photographs by the peak height and the integrated peak area, and in RI photographs by threshold setting. Finally, the lens concentration of Na + and K + and the protein composition were analyzed and correlated to the photographic analysis. RESULTS. The degree of the cataractous changes was most linearly related to dose and duration when the integrated peak area was estimated. However, protein fractions were non-linearly related to the cataractous changes estimated. Alterations in concentration of Na + and K + were small or insignificant, which indicate that naphthalene-induced cataract is not caused by osmotic changes. The lowest possible naphthalene dose to induce cataractous changes was between 0.10 and 0.50 g/kg twice a week for ten weeks. CONCLUSIONS. 0.50 and 1.0 g naphthalene/kg twice a week appeared to be optimal, because the rats in these groups were healthy and the cataractous changes were consistent between animals. Thus, the combination of the animal model with the cataract quantification system has the potential to be useful and reliable in studies of cataract-preventive compounds.

Mechanohydrogenation

Treatment of naphthalene and biphenyl with alumina and hydrogen in a vibratory mill for about 5h at ambient temperature gives up to 75 % and 15 % of tetralin and phenylcyclohexane respectively. This suggests that the previously reported [1]disproportionation of naphthalene and biphenyl to give tetralin and phenylcyclohexane by analogous treatment under nitrogen proceeds at least partially by a step involving molecular hydrogen. However, these observations are not general because identical mechanical treatment of trans-stilbene under hydrogen gave less bibenzyl than under nitrogen. © 1997 Elsevier Science Ltd. All rights reserved.