摘要:

A statistical structure‐activity equation has been developed for the estimation of carcinogenic potential for chemicals that have not been subjected to carcinogenesis assays. This discriminant equation is based on substructural fragments and molecular weight obtained for 343 compounds. The data base used for the design of the equation was obtained from the monographs of the International Agency for Research on Cancer. The accuracy of classification for the carcinogens in the model is between 87 and 91%, and for noncarcinogens between 78 and 80% in the presence of between 5.5 and 10.2% of the compounds not being classifiable. The false negative rate ranges between 4 and 5%; the false positive rate is near 11%.

ISSN:0098-4108    

DOI:10.1080/15287398209530273

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Data from the literature for 25 compounds belonging to different chemical classes were collected and their potency in the autoradiographic repair assay in rat liver cells was compared with their carcinogenic potency. A very modest correlation was found between the two parameters (v = 0.36). For 21 of the compounds it was also possible to compare mutagenic potency in the Ames test with carcinogenic potency. Even in this case the correlation was low (r = 0.40). The results are compared with those of previous studies of different short‐term tests used to predict carcinogenic potency.

ISSN:0098-4108    

DOI:10.1080/15287398209530274

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Twenty‐eight compounds of known teratogenic potential were assayed by an in vivo screening procedure. Postnatal growth and viability of prenatally exposed offspring was used as a measure of developmental toxicity. Gravid CD‐1 mice were administered maximum tolerated doses of the compounds for up to 5 consecutive days during the period of major organogenesis. The dams were allowed to give birth, and litter size and weight on postpartum d 1 and 3 were recorded and compared with concurrent controls. All 15 compounds that were teratogenic by standard teratology test criteria exhibited some form of developmental toxicity. Four chemicals known to produce only fetal toxicity (reduced weight or supernumerary ribs) were tested and the screen successfully identified those that reduced weight. Finally, of the 9 compounds that show no effect in standard tests, 6 were also negative in the screen and 3 demonstrated either reduced viability or weight.

ISSN:0098-4108    

DOI:10.1080/15287398209530275

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Teratogenic effects of two organophosphate insecticides, diazinon and dicrotophos, were investigated in regard to skeletal development, particularly of the extremities and vertebrae. Cartilage and calcified bone were examined with alcian blue and alizarin red S staining techniques, respectively, in chick embryos of d 5 to 17 of incubation. The age‐related development of both cartilaginous and ossified portions of the hind leg was measured in control and insecticide‐treated groups. Diazinon and dicrotophos (200 μg/egg), injected on d 3, inhibited growth of the following skeletal elements: femur, tibia, metatarsi and digits of the leg. The inhibition was noticeable from the 9th d of incubation. The greatest reduction of the skeletal length was observed in tibia and metatarsi, and was characterized by angulations toward the dorsal side. Percent of growth inhibition of the calcified region in the legs was similar to that of the entire length of each skeletal element, but there was no difference between control and insecticide‐treated groups on the time‐related appearance of cartilaginous or calcified long bones, digits, and phalanges of legs. In the cervical region of embryos treated with the insecticides, unique deformities such as an “undulating”; notochord and fused cervical rings were seen at an early stage (d 6). We suggest that the organophosphate‐induced malformations in legs are mainly due to growth regardation of later stages of development of each skeletal element. On the other hand, the neck deformities result from a profound alteration of differentiation at early stages of development.

ISSN:0098-4108    

DOI:10.1080/15287398209530276

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Two respirable coal fly‐ash samples (≤ 3 μm) were evaluated for physical properties, chemical composition, and biological activity, including cytotoxicity and mutagenicity. These two fly‐ash samples were collected from a pressurized fluidized‐bed combustion miniplant and from a conventional‐combustion power plant, both burning eastern coal. All samples were collected by a fabric filter downstream of the plant particulate control devices at 165° C (for fluidized‐bed combustion fly ash) or 130°C (for conventional combustion fly ash). The two coal fly‐ash samples were found to’ have different properties. Scanning electron microscopy illustrated a high degree of irregularity in fluidized‐bed combustion fly ash and sphericity in conventional‐combustion fly ash. Elemental analysis showed that fluidized‐bed combustion fly ash was higher in calcium, iron, chromium, nickel, selenium, and zinc, and conventional combustion fly ash was higher in aluminum, silica, arsenic, vanadium, and lead. Both fly‐ash samples were toxic in two mammalian cell systems, rabbit alveolar macrophages and Chinese hamster ovary cells in vitro, with fluidized‐bed combustion fly ash showing higher toxicity in both assay systems. The rabbit alveolar macrophage system was a more sensitive assay than the Chinese hamster ovary system. For measuring the cytotoxicity of fly ash, the most sensitive parameters were adenosine triphosphate in the rabbit alveolar macrophage system and viability index in the Chinese hamster ovary system. Intact fluidized‐bed combustion fly‐ash particles proved mutagenic only in tester strains TA98 and TA 1538 without metabolic activation in the Ames Salmonella typhimurium plate incorporation assay. For conventional‐combustion fly ash, no mutagenicity was detected in bioassay of the whole particles. A series of organic solvents with differing polarities was employed to identify the most efficient solvent for removing mutagens from coal fly ash. Soxhlet extraction yielded more extractable mass from fluidized‐bed combustion fly ash than from conventional‐combustion fly ash. The extracts of fluidized‐bed combustion fly ash were found to be mutagenic when dichloromethane, acetone, or cyclohexane were employed. These samples contained direct‐acting, frameshift mutagens. Much lower mutagenic activity was found in dichloromethane and acetone extracts of conventional‐combustion fly ash.

ISSN:0098-4108    

DOI:10.1080/15287398209530277

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Polycarbonate filter packets containing either mutagenic coal fly ash or beeswax pellets with 210 μg 7,12‐dimethylbenz[a]anthracene (DMBA) were placed in the lumina of heterotopic rat trachea/ transplants for 1, 2, 4, and 6 mo to test for carcinogenicity. Release of DMBA, as calculated from spectrophotometric determination of residual DMBA in removed beeswax pellets, was found to approach first‐order kinetics. The release rate was estimated to be 45.02% per month of the amount remaining in the pellets. Histopathological examination demonstrated in DMBA‐exposed tracheas consistent hyperplastic, metaplastic, and neoplastic changes (squamous‐celt carcinoma) by 2 mo post‐transplantation, when only 20.5% of total DMBA remained in pellets. These histopathological changes were not found in tracheas exposed to packeted coal fly ash or other control samples including loose coal fly ash, packeted heat‐inactivated fly ash, packeted glass beads, or empty tracheas. Mutagenicity tests with Salmonella typhimurium TA1538 showed that DMBA had a specific mutagenic activity of 10 revertants/μg upon metabolic activation. Coal fly ash had an activity of 236 revertants/mg when rat liver S9 was not incorporated and of 163.6 revertants/mg when the S9 was incorporated. The mutagenicity studies also showed that rapid release of ash mutagens in tracheal lumina occurred within 1 mo post‐transplantation. A t that time and thereafter, only about 25–40% of total mutagenic activity remained on the surface of ash particulates. An attempt was made to explain the failure to demonstrate carcinogenicity (in terms of neoplastic changes in tracheas) of coal fly ash. Results obtained from histopathological examinations of DMBA‐ or coal‐fly‐ash‐exposed tracheas, from specific mutagenicities, and from the rate of release of DMBA and coal fly ash into tracheal lumina were analyzed. Although coal fly ash produced 2.7 times more mutations (in terms of non‐histidine‐requiring revertant colonies) than DMBA at 2 mo post‐transplantation, it failed to induce any neoplastic changes in exposed tracheas. It is thus concluded that the critical factor is not the number of mutations produced per se, but rather the nature of the mutagen(s) responsible for carcinogenesis.

ISSN:0098-4108    

DOI:10.1080/15287398209530278

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The ability to maintain cytochrome P‐450 enzyme levels in stored tissue samples is necessary in order to properly utilize this enzyme system in toxicological and environmental health studies. The stability of enzyme activities associated with microsomal cytochrome P‐450 was investigated to determine the best way to handle large numbers of samples and postmortem or biopsy lung and liver tissue. Long‐term storage in cold buffer resulted in diminished activities in purified microsomes and whole tissue. Benzo[a]pyrene hydroxylase and 7‐ethoxycoumarin deethylase, however, were stable when the purified microsomal fraction, postmitochondrial fraction, or whole tissue was stored at —80°C, but care should be exercised in the freezing and thawing procedures.

ISSN:0098-4108    

DOI:10.1080/15287398209530279

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Air was sampled for viable bacteria in the shackling room of a poultry processing plant. Large numbers of bacteria were isolated from the workers’ breathing zone, and gram‐negative organisms were characterized. The probable source of airborne gram‐negative bacteria and their endotoxins was identified as the birds’ feces. These data suggest a potential health risk for workers due to inhalation of viable bacteria.

ISSN:0098-4108    

DOI:10.1080/15287398209530280

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The common roundworm of the dog, Toxocara canis, may also infect a number of other species including humans and mice. Previously, we found profound behavioral and neurological changes in mice infected with this parasite. The present investigation examined the relationship between dose of T. canis and changes in exploratory behavior in mice; issues raised in considering such relationships in a host‐parasite preparation are discussed.

ISSN:0098-4108    

DOI:10.1080/15287398209530281

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

A comprehensive scheme is described for isolating amosite asbestos and ferruginous bodies from fixed and unfixed human lung tissue and sputum. This qualitative procedure avoids many of the problems associated with previous isolation techniques and illustrates the advantages of brief bleach digestions. The samples are digested in prefiltered Wright laundry bleach (9.2% sodium hypochlorite), collected on 0.2‐μm Nuclepore filters by vacuum filtration, rinsed with distilled water and absolute ethanol, and examined visually for excessive residue. If organic residues are suspected or are known to occur, the sample is treated sequentially with 2% potassium permanganate, 8% oxalic acid, and 9.2% sodium hypochlorite, and rinsed with distilled water and absolute ethanol. The ethanol, potassium permanganate, and oxalic acid steps can be repeated as often as needed until the desired sample volume has been filtered. The entire procedure allows large volumes to be filtered and yields filters that have extremely clean backgrounds. Filtration can be completed in as little as 15 min, as opposed to the hours or days recommended for other procedures. The technique is applicable to specimens fixed in Saccomanno's fixative or giutaraldehyde, and to those in an unfixed state. The procedure does not appear to damage the gross morphology of the amosite fibers, and it does not produce a detectable change in their elemental composition when determined by energy‐dispersive X‐ray analysis.

ISSN:0098-4108    

DOI:10.1080/15287398209530282

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor