Does diisocyanate exposure result in neurotoxicity?

CONTEXT: Diisocyanates have been associated with respiratory and dermal sensitization. Limited number of case reports, and a few case studies, media, and other references suggest potential neurotoxic effects from exposures to toluene diisocyanate (TDI), 1,6 hexamethylene diisocyanate (HDI), and methylene diisocyanate (MDI). However, a systematic review of the literature evaluating the causal association on humans does not exist to support this alleged association. OBJECTIVE: To perform systematic review examining the body of epidemiologic evidence and provide assessment of causal association based on principles of the Sir Austin Bradford Hill criteria or considerations for causal analysis. METHODS: A comprehensive search of public databases for published abstracts, case reports, cross-sectional surveys, and cohort studies using key search terms was conducted. Additional searches included regulatory reviews, EU IUCLID and EU Risk Assessment databases, and unpublished reports in the International Isocyanate Institute database. An expert panel consisting of physicians, toxicologists, and an epidemiologist critically reviewed accepted papers, providing examination of epidemiologic evidence of each report. Finally, the Hill criteria for causation were applied to the summative analysis of identified reports to estimate probability of causal association. RESULTS: Twelve papers reporting exposed populations with a variety of neurological symptoms or findings suitable for analysis were identified, including eleven case or case series reports, and one cross-sectional study. Three papers reported on the same population. Each of the papers was limited by paucity of diisocyanate exposure estimates, the presence of confounding exposures to known or suspected neurotoxicants, a lack of objective biological measures of exposure or neurotoxic effects, and lack of relative strength of association measures. Additionally, reported health symptoms and syndromes lacked consistency or specificity. No plausible mechanism of toxicity was found. Application of a predictive mathematical model for determining probability of causal association for neurotoxicity was calculated to be 21%. CONCLUSION: There is insufficient evidence for a causal association of neurotoxic effects and diisocyanate exposure based on lack of evidence in all categories of the Hill criteria for causality except for temporal association of reported symptoms and alleged exposure. Future reports should attempt to address more rigorous exposure assessment and control for confounding exposures.

Detection and confirmation of reptilian adenovirus infection by in situ hybridization.

Adenovirus infections are documented in at least 12 different species of reptiles. In contrast to their mammalian and avian counterparts reptilian adenoviruses are not well characterized as to their pathogenic potential and their ability to cause primary disease. In the diagnostic setting, fresh tissues are often not available for virus isolation, and the confirmation of reptilian adenovirus infections is dependent largely upon electron microscopy for the identification of intranuclear viral inclusions associated with histopathologic changes. The diagnosis of adenovirus infection in 2 different species of snake was confirmed by the application of DNA in situ hybridization. Using an aviadenovirus specific oligoprobe, adenoviral DNA was observed in the nuclei of hepatocytes, Kupffer cells, endothelial cells, and enterocytes. Electron microscopy of the liver confirmed the presence of intranuclear viral particles morphologically consistent with an adenovirus. DNA in situ hybridization on formalin-fixed tissues can serve as a suitable alternative to electron microscopy in the diagnosis of reptilian adenovirus infections. Both affected snakes had other concurrent diseases, suggesting that the adenovirus may not have been the primary pathogen.

Immunolocalization of zona pellucida antigens in the ovarian follicle of dogs, cats, horses and elephants.

A comparative evaluation of the location of immunoreactive porcine zona pellucida (pZP) glycoproteins was performed with polyclonal rabbit anti-pZP antibodies on ovarian sections of the dog, cat, horse, and elephant. For this, formalin (light microscopy) and glutaraldehyde (transmission electron microscopy [TEM]) fixed ovarian sections were incubated with antibodies raised against highly purified pZP. Staining patterns were determined with diaminobenzidine (DAB) at the light level. The dog ZP had a distinct staining distribution that is characterized by intense staining around the periphery of the ZP and the oolemma and less dense staining throughout the width of the ZP. In dog follicles that contained multiple oocytes, there were oocytes of identical and dissimilar stages. Cat ovarian sections showed uniform staining of the ZP. Horse results showed uniform staining of ZP and ooplasm, and granulosa cells (GC). Elephant sections showed staining of the ZP with dense staining at the oolemma, as well as staining of the ooplasm. In all species the staining of the ZP was not evident until GC differentiation. In all cases there was no staining of ovarian tissue with control normal rabbit serum. Specific staining patterns of ZP were evaluated by TEM and immunogold staining. The immunogold-linked anti-pZP antibodies stained the ZP matrix in all species. There was staining of ooplasm organelles suggesting that ZP secretion originates from the oocyte of the dog and cat. In addition, follicular and ZP measurements were taken that allowed accurate characterization of follicle stage. These findings suggest that in all four species the ZP is recognized by anti-pZP antibodies and there is also evidence to suggest the possible origins of ZP glycoproteins.

Effects of dietary protein on glomerular mesangial area and basement membrane thickness in aged uninephrectomized dogs.

The primary objective of this study was to determine the effects of diets containing 18% or 34% protein on glomerular mesangial area (GMA) and basement membrane thickness (GBMT) in uninephrectomized aged dogs. A secondary objective was to determine the combined effects of aging and uninephrectomy on GMA and GBMT in dogs. Ten clinically healthy, pure-bred dogs were unilaterally nephrectomized at about 8 y of age. After 2 mo, 5 dogs were fed an 18% protein diet and 5 dogs were fed a 34% protein diet for 48 mo. At month 48, the dogs were euthanized and the remaining kidney was collected. Samples of kidney from both times of collection were used to measure GMA and GBMT using electron microscopy. The effects of diet on GMA and GBMT were analyzed (student's t-test) using necropsy/nephrectomy score ratios. The effects of time-nephrectomy were determined by comparing nephrectomy values for GMA and GBMT with necropsy values (paired t-test). Dogs fed 34% dietary protein did not have a significant increase in GMA and GBM thickness when compared to dogs fed the 18% protein diet. A significant increase in GMA and GBMT occurred with time-nephrectomy (P = 0.011 and 0.018, respectively). Although dietary protein intake was not a significant factor in causing structural changes to glomeruli in uninephrectomized aged dogs, the power to detect a difference was low. However, significant effects of aging and nephrectomy were detected despite the low power of the study. These results suggest that the increases in GMA and GBMT that occur over time are not markedly influenced by dietary protein intake. However, subtle protein effects cannot be eliminated as a possibility based on this study.

Lafora bodies associated with neurologic signs in a cat.

Lafora bodies (polyglucosan deposits) were identified in the brain of a young adult cat with neurologic signs characterized by intermittent but progressively worsening head and body tremors. The cerebellar cortex was the most severely affected area of brain, and the deposits were identified within Purkinje cell bodies and processes and throughout the neuropil. The association of Lafora bodies with neurologic signs, occurrence of deposits within neuronal perikarya, and distribution primarily within the cerebellar cortex are features distinct from the more commonly recognized situation in which Lafora bodies occur as incidental lesions in cats.

The occurrence of ambient temperature-regulated adhesins, curli, and the temperature-sensitive hemagglutinin tsh among avian Escherichia coli.

Escherichia coli establishes a secondary respiratory tract infection in birds following inhalation of contaminated dust and litter particles. Escherichia coli express adhesins under conditions reflective of the ambient temperatures present in poultry houses. These microbial adhesins allow E. coli to attach to cell types that it initially encounters in the respiratory tract. Ambient temperature-regulated adhesins represent a new class of bacterial hemagglutinins that include pili and the thin, aggregative, flexible filaments known as "curli." This study examines the occurrence of the ambient temperature-regulated adhesins, curli (crl, csgA), and an avian-specific, temperature-sensitive hemagglutinin, tsh, among avian and mammalian E. coli isolates. The avian hemagglutinin gene tsh was present in approximately 46% of clinical avian E. coli isolates. This gene was not detected among commensal E. coli isolated from healthy broiler chickens. Unlike tsh, curli genes were ubiquitous among E. coli. However, curli were observed in only half of the avian E. coli examined by electron microscopy. Curli were not present among several nonavian E. coli positive for crl and csgA. Approximately 25% of avian E. coli isolates agglutinated chicken erythrocytes when bacteria were grown at room temperature. Hemagglutination was not specific to E. coli isolated from poultry. Presence of either tsh or curli genes was not indicative of an isolate's ability to agglutinate chicken red blood cells. No discernible structures were observed mediating attachment of the bacteria to chicken red blood cells. An additional avian-specific hemagglutinin appears to be present among avian E. coli.

Colonization of the chicken trachea by an avirulent avian Escherichia coli transformed with plasmid pHK11.

Recombinant plasmid pHK11 was transformed into an avirulent, wild-type avian Escherichia coli (E. coli Av) in order to study the plasmid's effect on colonization of the chicken trachea. The transformant (E. coli Av + pHK11) produced colicin V (ColV), had type F1 fimbriae, and was motile. The E. coli Av recipient possessed type F1 fimbriae but was nonmotile; it did not produce ColV. Four-day-old chicks were inoculated in the trachea with 100 microliters of an overnight culture (approximately 10(8) colony-forming units) of E. coli Av, E. coli Av + pHK11, or sterile brain-heart infusion (BHI) broth. A group of uninoculated chicks was also included. Samples of the trachea were taken on days 4 and 10 postinoculation and compared histologically and bacteriologically. Birds inoculated with E. coli Av + pHK11 had enhanced tracheal colonization and showed increased histologic changes as compared with those inoculated with E. coli Av or BHI broth or uninoculated controls. These results indicate that production of ColV and motility enhance the colonization of the trachea and may be involved in the cause of pathologic lesions.

Occurrence of Loma cf. salmonae in brook, brown and rainbow trout from Buford trout hatchery, Georgia, USA.

During a 6 mo study of moribund trout from Buford hatchery, Buford, Georgia, USA, a Loma cf. salmonae microsporidian parasite was studied in the gills of brook trout Salvelinus fontinalis, brown trout Salmo trutta, and rainbow trout Oncorhynchus mykiss. This parasite was morphologically similar to L. salmonae and L. fontinalis but differed in spore size. Scanning and transmission electron microscopy demonstrated that xenomas were embedded in gill filaments. Transmission electron micrographs prepared from fresh tissue showed mature spores with 12 to 15 turns of their polar tube. Spore diameters for the Georgia strain from formalin-fixed gill tissues measured 3.5 (SD +/- 0.1) by 1.8 (SD +/- 0.1) microns. Electron micrographs of formalin-fixed, deparaffinized tissues of rainbow trout from Pennsylvania and West Virginia show spores with a diameter of 3.5 (+/- 0.2) by 1.7 (+/- 0.1) microns and 3.4 (+/- 0.2) by 1.8 (+/- 0.1) microns, respectively. Transmission electron micrographs of spores from Pennsylvania and West Virginia show that mature spores from both states had 13 to 15 turns of their polar tubes. Measurements from transmission electron micrographs prepared from alcohol-fixed tissues from Virginia fish contained spores with a diameter of 3.0 (+/- 0.3) by 1.1 (+/- 0.3) microns and 12 to 15 turns of their polar tubes. These measurements are consistent with L. salmonae and therefore suggest that the parasite is present on the east coast of the United States. During the height of the Georgia epizootic, the percentage of fish with observed xenomas reached 62.2% (N = 87), and the highest number of xenomas counted per 10 gill filaments was 133 (N = 87). The microsporidian epizootic occurred either during the autumn months or when intake river water quality reached combined iron-manganese concentrations as high as 1.01 (mean 0.44, SD +/- 0.42) mg-1.

Malignant chromatophoroma in a canebrake rattlesnake (Crotalus horridus atricaudatus).

An adult female canebrake rattlesnake (Crotalus horridus atricaudatus) at Zoo Atlanta (Atlanta, Georgia, USA) had a subcutaneous mass on the left lateral abdomen. Microscopically, the tumor contained a pleomorphic population of cells with abundant intracytoplasmic brown to gold nonrefractile pigment (chromatophores), large stellate cells resembling neurons, and small stellate cells whose cytoplasmic processes formed a fibrillar matrix. The pigment stained black with the Fontana-Masson technique and was positive with the periodic acid-Schiff technique (prior to and after diastase treatment). Neuron-specific enolase was detected in the large stellate cells using an immunohistochemical staining technique. In addition, glial fibrillary acidic and S-100 proteins were detected in the chromatophores with immunohistochemical staining. The smaller stellate cells were strongly S-100 positive. Ultrastructurally, chromatophores contained intracytoplasmic structures composed of concentric lamellar membranes bordered by a triple-layer outer membrane. The morphology of these structures was compatible with pterinosomes. Three fluorescent pigments were isolated from the neoplasm by one-dimensional chromatography and characterized by spectrophotometry and spectrofluorometry.

Immunogold for detection of avian leukosis/sarcoma virus in formalin-fixed heart and kidney.

Immunoprobes are used in the qualitative and semi-quantitative demonstration of antigens in clinical samples. In the present study, an immunogold method has been used for routine and rapid detection of avian leukosis/sarcoma virus (AL/SV) in sections of formalin-fixed chicken heart and kidney. Application of this ultrastructural indirect immunogold labelling technique (IILT) will enable pathologists to obtain a definitive diagnosis of avian AL/SV infection when inclusions or putative viral particles are observed by light or electron microscopy. IILT also may be used in research on AL/SV infections.

Transmission electron microscopic demonstration of abnormalities on the tracheal cilia of chicks exposed to formaldehyde during hatching.

Formaldehyde gas used to fumigate hatcheries for control of microbial contamination has an adverse effect on tracheal cilia function and morphology. Evaluation of the changes revealed alterations in the ultrastructure of the axoneme with the absence of B subfibers and the production of additional A subfibers. Spikes and vesicular blebs in the cilia walls were evident in formaldehyde-exposed cilia. These changes could result in ciliastasis and cilia loss.

[Toxicologic evaluation of pyrethroids in indoor air: demonstrated with the example of cyfluthrin and permethrin]. / Toxikologische Bewertung von Pyrethroiden in Innenräumen: Aufgezeigt am Beispiel Cyfluthrin und Permethrin.

Pyrethroids have varying activities depending on vehicle or route of administration (oral, dermal, inhalational). Specific features like the sensory irritation potential of the alpha-cyano-pyrethroids on the respiratory tract can only be quantified adequately by inhalation testing. Thus equitoxic dosages can vary between inhalative and oral application, especially for alpha-cyano-pyrethrolds. The no-effect values for chronic exposures derived for permethrin (type I pyrethroid) and cyfluthrin (type II pyrethroid) show clearly, that each pyrethroid has to be considered as an individual substance toxicologically, and that any extrapolation from the oral to the inhalative route should only be done after a thorough assessment of the specific toxicological profile. The study of simulated pest control measures on carpets pretreated with permethrin showed, that no significant enrichment of permethrin in total dust could be seen from a carpet additionally treated with pyrethroids. The missing correlation between absolute (mg pyrethroid/m3 air) and relative (mg pyrethroid/kg dust) concentrations in air-borne dust as well as the low degree of translocation of pyrethroids from carpets (only about 0.044% x m(-2) x h(-1) of the cyfluthrin applied to the carpet can be regarded as possibly respirable) prove, that analyses of pyrethroids in household sedimented dust ("vacuum cleaner bag analyses") without knowing the absolute surface concentration and respective air concentrations are of little value for risk assessment. The data allow the conclusion, that a scientific assessment of health risks is only possible based on absolute concentrations of pyrethroids in indoor air.

Polyomavirus encephalopathy in a Ducorps' cockatoo (Cacatua ducorpsii) with psittacine beak and feather disease.

Necropsy tissues were examined from an adult wild-caught Ducorps' cockatoo (Cacatua ducorpsii) with progressive neurologic signs. Of the tissue specimens selected for histologic evaluation, only the brain contained rare amphophilic, glassy intranuclear inclusions within astrocytes and some neurons. Astrocyte and neuronal degeneration and necrosis also were observed. Scattered astrocytes, with and without discernable inclusions, contained avian polyomavirus (APV) nucleic acid, as determined by DNA in situ hybridization. In addition, endothelial cells and intravascular leukocytes contained psittacine beak and feather disease viral nucleic acid, as determined by DNA in situ hybridization, indicating dual viral infection. Electron microscopic examination of formalin-fixed brain tissue revealed typical intranuclear APV particles in some astrocytes. Encephalopathy ultimately was attributed to APV infection.

[Nitrite formation and nitrosation potential of heterotrophic biological denitrification of drinking water in laboratory conditions]. / Untersuchungen zur Nitritbildung und zum Nitrosierungspotential bei der heterotrophen biologischen Denitrifizierung von Trinkwasser unter Laborbedingungen.

In a laboratory construction for heterotrophic biological denitrification of drinking water treatment, the formation of nitrite, the potency of nitrosation and the genotoxic activity were tested. Parameter as nitrate concentration, the water flow rate in the system, nitrite and morpholine addition and the pH-value were checked. For testing the potency of nitrosation and formation of nitrite in the reactor we took morpholine, a fast nitrosing amine. The results show for the break down rate of nitrate, there is no influence of the initial nitrate concentration (80-195 mg/L), the nitrite addition (5-20 mg/L) and the water flow rate (45-100 min) in the system. pH-values below 5.5 showed a little break down rate of nitrate. There was no correlation between the starting point of nitrate concentration and the formation of nitrite, although there was a positive correlation between the length of stay and the formation of nitrite. Nitrite concentrations of 5 mg/L with morpholine concentrations of 5 and 10 mg/L didn't show detectable formation of nitrosomorpholine. The analyses of different watertests in the construction didn't show significant results for DNA damage by the sister-chromatid exchange (SCE). The results of the Salmonella microsome assay (tester strain TA1535) didn't show any mutagenic effects relating to the potency of nitrosation. According to our experiments the potency of generalising nitrosamides or nitrosamines by drinking water denitrification seems to be low. There is no final assessment of detriment to health by denitrifying drinking water.

Detection of eastern equine encephalomyelitis virus RNA in formalin-fixed, paraffin-embedded tissues using DNA in situ hybridization.

Eastern equine encephalomyelitis (F.EE) virus was detected in infected formalin-fixed horse and emu tissues and in infected chicken embryo fibroblasts. Results of in situ hybridization using a digoxigenin-labeled 40-base DNA probe complementary to a conserved region of the EEE virus RNA compared favorably with results of both virus isolation and serum neutralization tests. This technique may be useful for diagnosis of EEE virus infection in various animal species, especially when fresh tissues are not available for analysis, and also will provide a means for studying the involvement of alphaviruses in pathogenesis studies.

Protein sparing effect and nutritive significance of lipid supplementation in carp diets.

Although carp is in a position to utilize carbohydrates efficiently, lipids are an important energy source in carp diets. In general fat-enriched high-energy diets result in rapid growth and favourable feed conversion. Many authors emphasize the protein-sparing effect of lipid supplementation in carp diets. For efficient protein-utilization an optimal protein/energy ratio in feed is necessary. Good results may be obtained with diets containing 30-50% high-quality protein, > 14 MJ digestible energy/kg and a lipid level of at least 15%. Low protein-high energy diets bring about low nitrogen excretion which is important for maintenance water quality. Lipid-supplemented diets lead to increased lipid content in the carp. Fingerling carp with high fat deposits exhibit an improved overwintering ability. By using fish oil as lipid source it is possible to produce carp meat with high concentrations of n-3 polyunsaturated fatty acids which are beneficial for human health.

Fringed membranous particles and viruses in faeces from healthy turkey poults and from poults with putative poult enteritis complex/spiking mortality.

The purpose of the present study was to use clinical epidemiologic tools to define the relationship between production performance data, virus particles, and intestinal fringed membranous particles (FMPs) in healthy turkey poults and in poults that were experiencing an outbreak of poult enteritis complex (PEC) and spiking mortality syndrome (SMS). Small and large intestines from flocks of healthy poults and poults with PEC/SMS were collected, processed, and examined for viruses. Production performance parameters were collected and analyzed. Hocks of turkeys with PEC/SMS in the present study had low survival expectancy (livability) and poor growth compared to their healthy turkey counterparts. The only significant association between sickness and intestinal virus was the presence of coronavirus.