Elevated lactoferrin is associated with moderate to severe Clostridium difficile disease, stool toxin, and 027 infection.

We evaluated blood and fecal biomarkers as indicators of severity in symptomatic patients with confirmed Clostridium difficile infection (CDI). Recruitment included patients with CDI based on clinical symptoms and supporting laboratory findings. Disease severity was defined by physician's assessment and blood and fecal biomarkers were measured. Toxigenic culture done using spore enrichment and toxin B detected by tissue culture were done as confirmatory tests. Polymerase chain reaction (PCR) ribotyping was performed on each isolate. There were 98 patients recruited, with 85 (87%) confirmed cases of toxigenic CDI (21 severe, 57 moderate, and seven mild), of which 68 (80%) were also stool toxin-positive. Elevated lactoferrin (p = 0.01), increased white blood cell (WBC) count (p = 0.08), and low serum albumin (p = 0.03) were all associated with the more severe cases of CDI. Ribotype 027 infection accounted for 71% of severe cases (p < 0.01) and patients with stool toxin had significantly higher lactoferrin levels and WBC counts (p < 0.05). Our findings show that elevated fecal lactoferrin, along with increased WBC count and low serum albumin, were associated with more severe CDI. In addition, patients infected with ribotype 027 and those with stool toxin had significantly higher fecal lactoferrin and WBC counts.

X-ray fluorescence: detection of lead in wall paint.

An instrument has been developed for the in situ determination of lead on painted surfaces. It utilizes, as a source of gamma rays, radioactive cadmium-109 and its daughter silver-109 (metastable) to excite the K series x-rays of lead, and a solid-state, lithium-drifted germanium detector. The device, which is capable of detecting 0.26 milligram of lead per square centimeter of paint [approximately 3 percent (by weight) of lead in a single coat] beneath ten layers of lead-free paint, has been tested in a preliminary survey of several tenement apartments in New York City.

Inhalation carcinogenesis of various alkylating agents.

A series of earlier studies showed that inhalation exposures of rats to three water-reactive electrophilic compounds produced brisk yields of nasal cancer even when the animals were exposed for only 30 days (6 hr/day X 5 day/wk). In addition, carcinogenic potencies of the compounds appeared to relate to their chemical reactivities as measured by hydrolysis rates. For a further study of this phenomenon, inhalation exposures were conducted with five additional water-reactive compounds: beta-propiolactone [(BPL) CAS: 57-57-8], methylmethane sulfonate [(MMS) CAS: 66-27-3], ethylchloroformate [(ECF) CAS: 541-41-3], dichloroacetyl chloride [(DCAC) CAS: 79-36-7], and propylene oxide [(PO) CAS: 75-56-9] on male Sprague-Dawley rats. The hydrolysis rates of these compounds span 6 orders of magnitude. The compounds were administered for 30 days (6 hr/day X 5 days/wk) with the use of exposure concentrations that were inversely proportional to the respective hydrolysis rates. With this protocol, all compounds except PO (the slowest reacting compound) produced nasal cancer in rats. The concentrations of MMS and BPL employed in the studies produced similar nasal cancer yields, indicating that the carcinogenic potencies of these compounds in rat nasal mucosa were proportional to their hydrolysis rates. The nasal cancer yields of DCAC and ECF were less than expected. DCAC hydrolyzes so rapidly at in vivo temperatures (half-life much less than 0.01 min) that it may not reach target DNA in reactive form. Why the exposures to ECF produced yields of nasal cancer not predicted by its reactivity is currently under investigation. These results combined with our earlier results demonstrate that the carcinogenic potencies of some inhaled reactive electrophilic compounds are related to their hydrolysis rates.

Inhibition of benz[a]pyrene-induced mammary carcinogenesis by retinyl acetate.

The administration of a 250-ppm retinyl acetate dietary supplement for various periods relative to intragastric administration of 50 mg benzo[a]pyrene (BP) significantly inhibited the induction of mammary cancers in virgin female inbred LEW/Mai rats. with day of BP administration taken as time 0, groups receiving the retinoid from weeks -2 to +1, +1 to +90, +20 to +90, and -2 to +90 showed a significant reduction in tumor response as compared to controls. The inhibition of carcinogenesis achieved by a +1 to +20 administration schedule was temporary; the tumor yield was suppressed initially but returned to control levels by week 60. Autoradiographic analysis of mammary glands from 50-day-old rats indicated that a 2-week exposure to supplemental retinyl acetate significantly reduced the mammary gland parenchymal cell labeling index in ductal, alveolar, and terminal end bud structures. Beginning the retinyl acetate supplement 1 week after the administration of BP significantly reduced the number of terminal ductal hyperplasias. The inhibition of carcinogenesis achieved by a short period of retinyl acetate administration before and during the period of carcinogen availability as well as the inhibition achieved by long-term postcarcinogen retinoid exposure may involve an antiproliferative effect on the rat mammary gland.

Rationale developed by the Environmental Protection Agency for the assessment of carcinogenic risks.

The intent of the Environmental Protection Agency's "Interim Guideline for Carcinogen Risk Assessment" is to provide an evaluation of the evidence regarding suspect carcinogens that encapsulates judgments on the quality and adequacy of data, the likelihood that the agent is a human carcinogen, and an estimate of the magnitude of the cancer burden that could be ascribed to the agent if no regulatory action were taken. Every effort shoult be made to reduce environmental contamination by carcinogens to the lowest possible level; this view stems from uncertainties about qualitative and quantitative extrapolations from animals to man, the lack of evidence for a dose threshold, the great range of possible interactions among environmental carcinogens and cofactors, and the broad spectrum of human susceptibility. New knowledge in the field of carcinogenesis is developing, and modifications of the Environmental Protection Agency's "Interim Guideline for Carcinogen Risk Assessment" must be made periodically.

A case-control study of hair dye use and breast cancer.

A case-control study of the relationship between hair dye use and breast cancer included 129 breast cancer patients and 193 control women drawn from the records of a multiphasic screening clinic. Information was obtained by telephone interview on a number of risk factors for breast cancer and on variables pertaining to hair dye use: chronologic time, duration, frequency, type, and color. From this, quantitative measures of cumulative hair dye use at various intervals prior to breast cancer (or an equivalent for controls) were obtained. A multivariate risk factor score was used to control for confounding variables. The adjusted relative risks for breast cancer versus hair dye use were greater than unity but were not generally significant. However, integral measures of hair dye use (No. of yr times frequency per yr) were significantly related to breast cancer when confounding variables were controlled. The association between hair dye use and breast cancer was greatest among women over 50 years of age and among those at lower natural risk for breast cancer. An analysis of temporal patterns showed that breast cancer was related mainly to hair dye use 10 or more years before cancer diagnosis. Because of the retrospective nature of the hair dye data and the small sample size, these results require further validation.

Gaseous formaldehyde and hydrogen chloride induction of nasal cancer in the rat.

The carcinogenic response to the combined and separate exposures to formaldehyde (HCHO) and hydrochloric acid (HCl) was investigated in male inbred SD rats. The rats were exposed to gaseous HCHO, 14 ppm, and HCl, 10 ppm, in two experiments. In one experiment the gases were premixed at high concentrations before being diluted in the exposure chamber air to maximize the formation of the carcinogen bis(chloromethyl)ether (BCME). In the second experiment exposure was repeated to HCl and HCHO premixed at high concentrations, and not premixed (to minimize BCME formation), as well as to HCHO alone and HCl alone. The second experiment is being reported on at an interim stage. HCHO alone induced squamous carcinomas of the nasal cavity as did the combined exposures to HCHO and HCl. No carcinogenic response was observed with HCl alone. HCHO accounted for most, if not all, of the carcinogenic activity of the mixture of HCHO-HCl.

Breast neoplasms in women treated with x-rays for acute postpartum mastitis.

Breast cancer has been studied by mail survey up to 34 years in 571 of 606 women treated with x-rays for acute postpartum mastitis. The incidence of neoplasms was compared with that of three nonirradiated control groups--nonirradiated sisters of the treated women, women with acute postpartum mastitis not treated with X-rays, and their nonirradiated sisters. For the irradiated group, with mean dose of 247 rads to both breasts, the overall relative risk of breast cancer was 2.2 for years 10-34 post irradiation and 3.6 for years 20-34. The dose response for malignant and benign breast neoplasms was compatible with a linear fit. For comparable total doses, fractionation of exposure did not reduce carcinogenic action. Women over age 30 years at radiation treatment had as great an excess risk of breast cancer as did younger women. The overall excess risk of developing breast cancer was about 8-10 cases per million women per rad per year, an increase of about 0.5% per rad.

Inhalation carcinogenicity of epichlorohydrin in noninbred Sprague-Dawley rats.

Inhalation exposure experiments with the direct-acting alkylating agent epichlorohydrin (ECH) were done on noninbred male Sprague-Dawley rats. Single 6-hour exposure to ECH and follow-up for 14 days showed the median lethal concentration to be about 360 ppm. Further inhalation experiments were done with 6-hour exposure 5 days/week. A short-term 30-exposure regimen with 100 ppm ECH produced malignant squamous cell carcinomas of the nasal cavity in 15 of 140 rats and respiratory tract papillomas in 3 rats. Among 100 rats, lifetime exposure to 30 ppm yielded 1 malignant squamous carcinoma of the nasal cavity plus 1 nasal papilloma. No nasal or respiratory tract tumors were produced by lifetime exposure of 100 rats to 10 ppm. As controls, 100 air-treated and 50 untreated rats were used. A dose-rate effect was observed for ECH inasmuch as 30-day exposure to 100 ppm (3,000 ppm-days) produced 15 cancers in comparison to the 1 cancer from the lifetime exposure to 30 ppm (8,700 ppm-days) and no cancers from lifetime exposure to 10 ppm (2,500 ppm-days).

Dose response for benzo(a)pyrene adducts in mouse epidermal DNA.

The dose dependency of the binding of benzo(a)pyrene (BaP) with DNA of mouse epidermis was investigated. BaP-conjugated epidermal DNA was isolated and enzymatically degraded to deoxyribonucleosides. The BaP-DNA adducts were separated by Sephadex LH-20 column or high-performance liquid chromatography. Two major BaP-DNA adducts were found. One was in the region of the elution profile that contained polycyclic aromatic hydrocarbons adducted to deoxyribonucleosides. The other adduct was eluted from Sephadex LH-20 and high-performance liquid chromatography columns before the deoxyribonucleosides and after deoxyribonucleotides. Both adducts of BaP in epidermal DNA reached a maximum 7 hr after a single skin application, and subsequently little, if any, loss of adducts was observed for 49 hr. Both adducts varied as a linear function for topical doses in the range from 0.01 to 300 microgram/mouse. The formation of DNA adducts by BaP occurred in proportion to dose at doses several orders of magnitude below those that are feasible to test for carcinogenicity.

Transplacental skin tumor initiation of Ha/ICR mice at different fetal ages.

The initiation of cells in fetal skin was studied by exposing pregnant Ha/ICR mice intragastrically to single doses of a carcinogen at different times during gestation. For comparison, adult mice were exposed to the same carcinogen in a similar manner. The carcinogen, 7,12-dimethylbenz(a)anthracene (DMBA), was given at a dose of about 120 mg/kg in 0.2 ml sesame oil by gavage to 7-week-old pregnant females. The presence of initiated cells in the adult offspring was determined by topical application of 5.0 micrograms in 0.2 ml acetone of the skin tumor promoter tetradecanoyl-12-phorbol-13-acetate to the skin three times weekly beginning at 9 weeks of age. The yield of tumors was determined as a function of time during continuous promotion. Evidence of initiated cells was found in adults exposed transplacentally to DMBA as early as Day 9 of fetal development. The histological characteristics of the tumors and their temporal pattern of development were essentially the same for mice exposed at different stages of fetal development as they were for mice exposed to DMBA as adults. Male and female offspring exhibited approximately the same tumor yields. The use of [3H]DMBA and autoradiographs provided evidence that the cellular dose of DMBA was approximately equivalent at each stage of gestation and in adult skin. The results suggest that the number of initiated cells produced by a given dose of DMBA to the epidermis or fetal ectoderm is proportional to the number of cells in the tissue at the time of exposure.

Regression kinetics of mouse skin papillomas.

The persistence and proliferation rate of mouse skin papillomas were studied in HA/ICR mice initiated with 7,12-dimethylbenz(a)anthracene and promoted three times weekly with phorbol myristate acetate. When the promoter treatments were stopped, rapid (half-time, 24 days) and slow (half-time, greater than 140 days) components of papilloma regression were observed. When the promoter dose was increased, the major effect was an increase among the rapidly regressing papillomas. Increases in the epidermal pulse-labeling index and the number of dermal inflammatory cells produced by phorbol myristate acetate in normal skin were reversible when the phorbol myristate acetate was stopped, but high pulse-labeling index values in papillomas were not reversible. Antithymocyte serum had no effect on regression, although ethylphenylpropriolate, a nonpromoting irritant, slowed the regression sufficiently to increase the half-time from 24 to 57 days. The action of the promoter in overcoming the regression tendency of the papillomas may explain certain features of the role of nonspecific irritation and the importance of promotion frequency in determining tumor yield.

Effect of carcinogens on chicken atherosclerosis.

Weekly i.m. injections of the polycyclic hydrocarbon carcinogens, 7,12-dimethylbenz(a,h)anthracene (DMBA; 25 mg/kg/injection) and benzo(a)pyrene (50 mg/kg/injection) were given for a period of up to 22 weeks to chickens (SC strain) beginning at age 4 weeks. Atherosclerotic lesions of the abdominal aorta occurred more frequently and were larger in the DMBA- and benzo(a)pyrene-treated birds than in controls. These lesions were proliferative in character as indicated by a higher [3H]thymidine autoradiographic labeling index compared to the underlying medial cells of the aorta. Measurements of serum cholesterol in DMBA-treated birds showed no differences from controls. Although both carcinogens accelerated the development of atherosclerotic plaques, DMBA was more potent than benzo(a)pyrene.

Cell proliferation and nuclear abnormalities are increased and apoptosis is decreased in the epidermis of the p53 null mouse after topical application of benzo[a]pyrene.

Cell proliferation and cell death in mouse epidermis are altered by topical application of benzo[a]pyrene (BaP), a procarcinogen, which yields metabolites that can form DNA adducts. The mitotic rate, nuclear abnormalities, labelling index, grain density, necrosis and apoptosis were compared in the epidermis of TSG-p53 null (p53-/-) and C57BL wild-type (wt) mice after weekly treatments with BaP to determine whether the absence of the p53 gene altered cytokinetic responses to DNA damaging agents in vivo. Acetone alone or 64 micrograms BaP in 50 microliters acetone was applied to the clipped dorsum of mice once, or in four consecutive weekly treatments. Indices of cell proliferation and cell death were the same in both wt and p53-/- mice treated only with acetone. One application of BaP depressed mitosis and slowed the rate of DNA synthesis in both genotypes. After four applications of BaP the number of keratinocytes in S phase increased substantially, while there was no further slowing in the rate of S phase in the wt and p53-/- mice. Cell proliferation rates and numbers of cells with nuclear abnormalities were higher and there were fewer apoptotic cells and apoptotic bodies in the p53-/- mice than in the wt mice. Numbers of 'sunburn' cells were similar in both types.

Life span and cancer mortality in the beagle dog and humans.

This study compares the age-dependence and rate of cancer mortality in untreated Beagles over a lifetime with that of Japanese and US white men and women. The purpose of the study was to determine the extent to which there is a linkage between life span and cancer mortality in Beagle dogs and humans. The two human populations were chosen to represent contrasting races and environments. Using the age at 10% survival as the measure of life span, about 5.5 years in humans was equivalent to 1 year of life in Beagles. The age dependence and total cancer mortality was the same in men and male Beagles. The age dependence was the same in female Beagles and women, but the total cancer mortality was somewhat greater in female Beagles due to more breast cancer. Cancer in Beagles, other than breast cancer in females, consisted mostly of sarcomas and lymphomas. There was very little cancer in environmentally exposed tissues (lung and intestine). There was also some contrast between Japanese and Americans in the relative rates of cancer at certain sites. The study provides support for the life span linkage of adult cancer mortality in the two species, in spite of the different patterns of cancer types and environments.

Relationships between the levels of binding to DNA and the carcinogenic potencies in rat nasal mucosa for three alkylating agents.

Three direct-acting carcinogens, beta-propiolactone (BPL), methylmethane sulfonate (MMS), and dimethylcarbamyl chloride (DMCC), were evaluated for their carcinogenic potencies in the nasal mucosa of rats and for their abilities to bind in vivo to rat nasal mucosal DNA. The relative carcinogenic potencies of BPL and MMS corresponded well with their overall levels of binding to nasal mucosal DNA. DMCC, however, the most potent carcinogen of the three compounds, produced the lowest level of binding to nasal mucosal DNA. These results indicate that the DNA adducts formed by DMCC in rat nasal mucosa DNA are more readily expressed as cancer than those formed by BPL or MMS.

Comparative carcinogenic potencies of particulates from diesel engine exhausts, coke oven emissions, roofing tar aerosols and cigarette smoke.

Mammalian cell mutagenesis, transformation and skin tumorigenesis assays show similar results in comparing the potencies of diesel, coke oven, roofing tar and cigarette smoke particulates. These assay results are reasonably consistent with the comparative carcinogenic potencies of coke oven and roofing tar emissions as determined by epidemiological studies. The bacterial mutagenesis assay tends to show disproportionately high potencies, particularly with diesel particulates. Results to date encourage the approach to the assessment for carcinogenic risks from diesel emissions based on the use of epidemiological data on cancer induced by coke oven emissions, roofing tar particulates and cigarette smoke with the comparative potencies of these materials determined by in vivo and in vitro bioassays.

Issues in the risk assessment of chromium.

Although hexavalent chromium is well established as a human carcinogen by the inhalation route, there are significant uncertainties in the quantitative estimation of cancer risk. One of the important uncertainties is the assumption that the carcinogenic potency, determined under conditions of occupational exposure where most workers were cigarette smokers, applies to the nonsmoking individual in the general population. There is substantial evidence that carcinogenicity is a function of the rate of cell turnover in the target tissue. The chromate worker would be expected to have a relatively high rate of cell proliferation in the bronchial mucosa due to airborne irritants and smoking. The potency of chromium might therefore be relatively high under conditions of occupational exposure. This problem in quantitative risk assessment applies equally well to another important indoor pollutant, radon.

Allergic contact sensitizing chemicals as environmental carcinogens.

Chemicals that were bioassayed by the National Toxicology Program (NTP) and that also produce allergic dermatitis (ACD) in humans were evaluated for their tumorigenic characteristics. The impetus for the study was that most contact sensitizers, i.e., those that produce ACD, and genotoxic carcinogens are chemically similar in that they are electrophilic, thereby producing adducts on macromolecules including protein and DNA. This similarity in chemical behavior suggests that many contact sensitizers might be environmental carcinogens. All of the published NTP bioassays by early 1996 that had both genotoxicity and carcinogenicity studies were included in this analysis. The NTP chemicals had been chosen for bioassay without regard to their ability to produce ACD. Of the 209 chemicals that were bioassayed, there were 36 (17%) that were known to be human contact sensitizers; about half of these were positive on tumor bioassays. The contact sensitizers differed from the NTP sample as a whole by having a proportionately larger number of nongenotoxic chemicals by the Ames Salmonella assay, presumably because more of them were selected on the basis of widespread usage rather than structural resemblance to known carcinogens. Compared to the nongenotoxic chemicals, the genotoxics were stronger carcinogens in that they had a higher incidence of positive tumor bioassays, with twice the number of organs in which tumors were induced. The nongenotoxic chemicals had a preference for tumor induction in parenchymal tissues in contrast to epithelial tissues. The contact sensitizers showed essentially the same characteristics as the whole NTP sample when stratified according to genotoxicity. Judging by the chemicals that were chosen primarily for their widespread use rather than for their structural resemblance to carcinogens, the addition of a test for contact sensitization to the Ames test as a screening tool would increase the tumorigenic detection efficiency by about 40% because of the nongenotoxic tumorigens. A ballpark estimate suggests that there could be several thousand contact sensitizers for humans in commercial use that are rodent tumorigens.

Carcinogen risk assessment.

A molecular biological rationale for the linear nonthreshold dose-response pattern for carcinogenesis is presented based on the mutagenic activation of oncogens as the basis of initiation. The approach assumes that the linear nonthreshold dose pattern at very low doses applies only to tissues that are promoted by intrinsic and extrinsic agents other than the one being modeled, and that risk is characterized on a relative rather than absolute basis in terms of aggregate tumor response.