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PubMed1996

Monitoring human lymphocytic DNA-protein cross-links as biomarkers of biologically active doses of chromate.

A simple and sensitive assay for DNA-protein cross-links has been used as a biomarker of chromate exposure and early carcinogenic effects. Pilot studies of DNA-protein cross-links in peripheral blood lymphocytes have been conducted with individuals who had higher exposure to chromate, including welders, and with individuals who had lower levels of exposure such as residents living in a chromium-contaminated area in Jersey City, New Jersey. Studies were also conducted in two Bulgarian cities (Jambol and Burgas) with different levels of air pollution and Cr(VI) exposure and in chrome platers in Bulgaria who had high exposure to chromate. DNA-protein cross-links in U.S. welders and in individuals living in Hudson County, New Jersey around chromium-contaminated areas were significantly higher compared to matched controls. Although blood and urinary levels of chromium were not extensively studied in these populations, we were able to obtain these measurements in the Bulgarian population. Chromium levels in red blood cells of controls living in Burgas were in the order of 1 to 2 ppb chromium, and these individuals had the lowest levels of DNA-protein cross-links. However, the chromium levels in Jambol ranged from about 2 to 7 ppb in red blood cells of city residents to about 22 ppb in chrome platers. DNA-protein cross-links were saturated at about 7 to 8 ppb chromium in the red blood cells, and cross-links correlated well only with chromium levels in red blood cells. Urinary chromium levels did not correlate well with either DNA-protein cross-links or chromium levels in with red blood cells.

Biomarkers↗
PubMed1981

[Occupational impairment of the olfactory sense of chromate producing workers (author's transl)].

Using T & T Olfactometer which had been developed and standardized for clinical use in Japan recently, measurements of olfactory thresholds of odor detection and of odor recognition were carried out on 33 subjects (26 males and 7 females), who had worked in a chromate producing factory. The subjects had left the factory before 7 years or more. Five kinds of test odors were used; beta-phenyl ethyl alcohol, methyl cyclopentenolone, iso-valeric acid, gamma-undecalactone, and scatol. The degree of olfaction loss was expressed with the number of powers of 10 in series of multiple concentrations by 10 of each test odor with reference to the concentration of the detection threshold of young normal people. Seventeen of 33 subjects (51.4%) had a perforation of the nasal septum. Middle and high grade decrease of odor recognition faculty were found in 18 (54.5%) including 2 anosmia, one of whom complained also of the disorder of taste. Any specific pattern of olfactogram characterizing them were not found, namely, chromates impair olfactory sense for all kinds of odors, which means the impairment of olfactory epithelium itself. The degree of olfaction loss was related to the duration of employment in the chromate producing factory. The existence of septal perforation had no direct relation to the degree of olfaction loss.

Adult↗
PubMed1985

In vivo clastogenicity of lead chromate in mice.

Cytogenetical effects of lead chromate were evaluated in vivo. When 0.5, 1, 2 and 4 g/kg body weight of lead chromate suspensions in 0.5% gum arabic were administered i.p. to C57BL/6N male mice twice, the frequencies of micronucleated polychromatic erythrocytes in the femoral bone marrow were significantly (p less than 0.01) different from that in the vehicle control. Moreover, as the dose increased, the ratio of the polychromatic to normochromatic erythrocytes decreased in a dose-response fashion (p less than 0.05). Thus, it is concluded that lead chromate in vivo gives rise to chromosomal damage as well as disturbance in hematopoiesis.

Animals↗
PubMed1986

Stabilization of silver chromate Golgi impregnation in rat central nervous system neurons using photographic developers. I. Light microscopy.

Deterioration of Golgi impregnation begins immediately after impregnated tissue blocks are sectioned with the Vibratome. The first signs of deterioration are fading of delicate impregnated processes, the disruption and fragmentation of dendrites, and, eventually, fading of entire neurons. These changes can be prevented by stabilization, i.e., by converting the water soluble silver chromate Golgi precipitate into metallic silver or by replacing the silver with some other dense, insoluble material. A technique is described using photographic developers to treat Vibratome sections containing Golgi-rapid or Golgi-Kopsch impregnated CNS neurons. In this way part of the silver chromate Golgi precipitate is reduced to metallic silver, and the remaining silver chromate is then removed with sodium thiosulfate. Of the various developers tested, Kodalith and Elon-ascorbic acid gave the best results, with excellent stabilization of the most delicate structures, such as the stalks of dendritic spines and finely woven axonal plexuses. Treatment with other developers (HC-110, Neutol, D-19, D-76, D-163, Kodak Universal, Rodinal, Atomal, Diafine, Eukobrom, Microdol-X) resulted in stabilization ranging from good to poor. Good stabilization of Golgi impregnation could also be achieved by first exposing the sections to sodium bromide (bromide substitution) followed by treatment with D-19, Kodalith, Elon-ascorbic acid or HC-110. After stabilization, the sections can be counterstained with aqueous cresyl violet or with alcoholic thionin without degradation of the stabilized Golgi image. The counterstain permits exact determination of the position of impregnated neurons in cortical layers or subcortical nuclei.

Animals↗
PubMed1990

Chromate sensitization and elicitation from cement with iron sulfate.

For some years, iron sulfate has been added to cement manufactured in the Scandinavian countries to prevent sensitization to and elicitation from chromate in cement. Allergic contact dermatitis from chromate is reported here in 3 workers with hand dermatitis and exposure to cement containing iron sulfate. Although iron sulfate had been added to the cement, high chromate concentrations were found in many samples of cement to which these workers were exposed.

Adolescent↗
PubMed1976

Tumorigenic activity of lead chromate.

Lead chromate was investigated for its carcinogenic potential in both rats and mice. Results show that this compound is a very potent carcinogen in rats when administered i.m. Sixty-four % of the animals treated developed malignant tumors at the injection site. Three renal carcinomas were also found after i.m. treatment with lead chromate. Since lead powder is a comparatively weak carcinogen in rats, whether given p.o. or i.m., it is suggested that the combination of lead and chromium (also weak carcinogen) accounts for the high carcinogenic activity of lead chromate in rats. Swiss albino female mice could not tolerate the same high dose level as did the rats; at the lower dose administered to the mice, no tumors were detected.

Animals↗
PubMedDate not supplied

[Use of immobilized cells of bacteria in the process of purification of waste water containing chlorates and chromates].

Some regularities of immobilization of chlorate-reducing bacteria by various carriers and especially sewage treatment for chlorate and chromates by adhered bacteria have been studied. Most bacterial cells are immobilized during the first hour of contact with the carrier. The studied carriers, as to their ability to adsorb Aerococcus dechloraticans TGS-463 cells, may be arranged in the following sequence: porolon > claydite > glass broaches > maize stem > barley straw. The 12-24 hour culture Aerococcus dechloraticans TGS-463 expresses maximum ability to immobilization. The bacterial cell fastening on the carrier increases 2.1 times the reduction velocity for chlorates and 1.6 times that for chromates. The velocity of chlorates and chromates reduction by the culture factened on the carrier decreases in the due course of time, that requires the carrier regeneration.

Bacterial Adhesion↗
PubMed1990

Nucleotide sequence and expression of a plasmid-encoded chromate resistance determinant from Alcaligenes eutrophus.

The nucleotide sequence of the 2.6-kilobase pair (kb) EcoRI fragment encoding chromate resistance (Chrr) on plasmid pMOL28 in Alcaligenes eutrophus was determined. Three open reading frames were assigned to three polypeptides which were expressed from this determinant in Escherichia coli under the control of a phage T7 transcription promoter. When the roles of the polypeptides and open reading frames were analyzed with deletion derivatives of the 2.6-kilobase fragment, the membrane-bound ChrA (401 amino acids) and ChrB (196 amino acids) polypeptides were essential for inducible chromate resistance and reduced accumulation of chromate, while the third open reading frame was not needed.

Alcaligenes↗
PubMed1989

Analysis of proteins cross-linked to DNA after treatment of cells with formaldehyde, chromate, and cis-diamminedichloroplatinum(II).

The proteins cross-linked to the DNA of cultured Chinese hamster ovary cells after exposure to cis-diamminedichloroplatinum(II) (cis-Pt), chromate, and formaldehyde were compared by two-dimensional (2D) gel electrophoresis, immunoblotting, and centrifugal assays that measured cross-link stability. Chromate and cis-Pt cross-linked seven of the same nonhistone proteins, such as actin, to DNA. In contrast, formaldehyde selectively formed histone-DNA cross-links. Immunoblotting experiments showed that all three chemicals cross-linked a 97-kDa nuclear protein to the DNA despite their different chemical reactivity with DNA and proteins. The chromate- and cis-Pt-induced cross-links were disrupted by thiourea, 2-mercaptoethanol, and EDTA, indicating that the metal could be chemically displaced from the cross-links. The formaldehyde-induced complexes required degradation with DNase 1 for the resolution of histones on 2D gels and were not chemically labile like the metal-induced cross-links. The agents and methodology used here could be applied to the study of additional nuclear proteins that bind or reside near the DNA.

Animals↗
PubMed1985

Lung cancer in chromate workers--analysis of 11 cases.

We have experienced 11 cases of lung carcinoma in workers at a chromate factory during the past 14 years. All patients were males. The age of onset ranged from 41 to 68 years. Ten of the 11 were heavy smokers. The time of exposure to chromate was from 17 to 29 years and the average was 23.9 years. Seven patients had perforation of their nasal septa. The primary sites of the cancers were from the lobar to the subsegmental bronchi. There were nine squamous cell carcinomas and three small cell carcinomas. Four squamous cell carcinomas were hilar type early stage cancers and two of them were found in one patient at the same time. The chromium content of the lung tissue in the seven patients tested was from 13.9 to 2,368.4 micrograms/g of dry tissue and was higher than that of lung cancer or non-lung cancer cases without chromate exposure. There was no severe dysplasia of the bronchial epithelium in these 11 patients.

Adult↗
PubMedDate not supplied

[Pure culture of bacteria using chromates and bichromates as hydrogen acceptors during development under anaerobic conditions].

A pure bacterial culture utilizing chromates and bichromates as oxygen donors during growth on organic substances in anaerobic conditions was isolated from active ooze of sewage and industrial wastes containing a weak solution of chromates. A medium for growth of the bacterium was selected, and its morphological and cultural properties were studied. Chromates and bichromates are reduced only in anaerobic conditions by the bacterium or active ooze containing it, the hexavalent chromium becoming trivalent. The culture does not belong to any known species and has been therefore classed as Pseudomonas dechromaticans.

Anaerobiosis↗
PubMed1998

Dermal and respiratory sensitization to chromate in a cement floorer.

BACKGROUND: To report a well-documented case of both allergic contact dermatitis and occupational asthma due to chromate exposure in a 48-year-old floorer. METHODS AND RESULTS: A 48-year-old floorer, occupationally exposed to cement and with a documented chromate contact dermatitis, reported dyspnea and wheezing after work. These conditions were demonstrated by self-measured sequential peak expiratory flows. A first bronchial provocation (BPT) with potassium dichromate (K2Cr2O7) (0.3% nebulized for a total of 60 minutes) led to pronounced and sustained decreases in forced expiratory volume in 1 second (FEV1) and forced vital capacity, accompanied by pruritus, a decrease in arterial PO2, a slight rise in temperature, and peripheral blood leukocytosis. (This concentration of K2Cr2O7 is not recommended for BPT). Bronchoalveolar lavage performed 2 days later showed 18% eosinophils. Tow years later, a BPT with a lower dose of K2Cr2O7 (0.01% for the total of 31 min) led to an "earl late" reaction (FEV1 dropped by 195 compared with the initial FEV1 value), accompanied by pruritus. A BPT with dry cement, containing 12 ppm hexavalent chromium, was borderline (FEV1 dropped by 13%), and a similar result (FEV1 dropped by 14%) was obtained after smoking five cigarettes, laced with 10 mg of cement per cigarette. CONCLUSIONS: This report illustrates that a subject, with allergic contact dermatitis to chromates, may develop a respiratory allergic reaction to an airborne source of this metal. The main novelty of our report is that the smoking of cigarettes contaminated with cement may have been significant factor in the causation or elicitation of these reactions.

Asthma↗
PubMed2002

Control of the morphogenesis of barium chromate by using double-hydrophilic block copolymers (DHBCs) as crystal growth modifiers.

A systematic morphosynthesis of barium chromate particles has been performed by using double-hydrophilic block copolymers (DHBCs), which consist of a hydrophilic solvating block and a hydrophilic binding block, as crystal growth modifiers to direct the controlled precipitation of barium chromate from aqueous solution. Several kinds of DHBCs with different functional groups -COOH, -PO3H2, -SO3H, -SH as well as PEG-poly(aminoamine) block-dendrimer copolymers were explored for crystallization and morphology control of barium chromate. Well-defined morphologies of BaCrO4 particles can be produced, such as more or less dendritic X-shaped, elongated X-shaped, or rodlike particles, flower-like plates, ellipsoids, spheres, nanofiber bundles, nanofibers, and other more complex morphologies. In the presence of the phosphonated copolymer PEG-b-PMAA-PO3H2 (degree of phosphonation: 21%) at pH 5, large conelike bundles of nanofibers ranging from 10 to 20 nm in diameter with lengths up to 150 microns can be produced at room temperature, whereas replacement of the covalently bound phosphonate groups by the ionic salt analogue dopant fails to produce this structure, indicating the importance of the functional polymer block structures. The time-resolved formation process of the bundles of nanofibres was investigated, showing a remarkable self-similarity. At temperatures higher than 50 degrees C, in plastic flasks or when undergoing continuous stirring, only ellipsoids or nearly spherical particles can be obtained. This shows that the fiber formation relies on heterogeneous nucleation and is in agreement with a recently published mechanism where fiber formation is due to the vectorially directed self-assembly of primary particles. Our results demonstrate that the integration of DHBCs, taking advantage of the experimental conditions such as crystallization sites, temperature, pH, and reactant concentration, will extend the possibilities for controlling the shape, size, and microstructures of the inorganic crystals by means of a simple mineralization process.

Journal Article↗
PubMed1992

The influence of lens chromatic aberration on electron energy-loss spectroscopy quantitative measurements.

An investigation has been made into the effect of chromatic aberrations of a pre-spectrometer lens system on quantitative elemental analysis by electron energy loss spectroscopy (EELS). In transmission electron microscopy (TEM) diffraction mode, the measured effects are typically 150-330 times larger than if only objective-lens chromatic aberration were important. We discuss several methods of avoiding errors arising from chromatic aberration, including selection of a suitable optical mode (dependent on the desired spatial resolution), adjustment of the TEM imaging system so as to focus the system for a chosen energy loss, and analysis of a large area of a uniform specimen.

Electron Probe Microanalysis↗
PubMed1995

Further exploration of human neonatal chromatic-achromatic discrimination.

Newborn (n = 140) and 1-month-old (n = 120) human infants were habituated to achromatic ("white") squares of varying luminance (.35 to 1.16 log cd/m2) and then tested for recovery of habituation with chromatic stimuli from particular spectral locations. Results showed that newborns appear to discriminate 32 degrees yellow-green (dominant lambda = 565 nm) from white, but not 16 degrees or 32 degrees blue (450 nm), 16 degrees blue-green (493 nm), 16 degrees or 32 degrees yellow-green (572 nm), or 16 degrees purple from white. Performance of 1-month-olds was marginally better than that of newborns. Combined with our previous results with the habituation method, these data imply that newborns show little ability to make any chromatic-achromatic discriminations when stimulus size is smaller than 8 degrees, and that even with very large stimuli (e.g. 32 degrees) performance is relatively poor in the blue and yellow-green spectral regions. Although several models were considered, these limitations in the short- and mid-wavelength regions may best be accounted for by the argument that young infants possess general rather than selective immaturities or inefficiencies within their chromatic mechanisms.

Child Development↗
PubMed1984

Selective damage to chromatic mechanisms in neuro-ophthalmic diseases I. Review of published evidence.

Acquired color deficiencies may correspond to a general, non-selective loss of visual sensitivity. We summarise evidence for the opposite view that, in some cases, chromatic sensitivity can be more (or less) reduced than achromatic sensitivity. This evidence is based on: (1) Disproportion between chromatic and achromatic isopters; (2) Differential damage to red-green and blue-yellow color vision; (3) Detection static perimetry; (4) The foveal photochromatic interval; (5) The two color threshold technique; (6) Spectral sensitivity on a white background; (7) Single unit and histological studies of the retina and lateral geniculate nucleus; (8) Lesions of the prestriate color area; (9) Selective damage to achromatic processes. Possible problems of interpretation are considered and a new technique for comparing chromatic and achromatic sensitivity is briefly described.

Animals↗
PubMed1976

The size, density, and relative area of chromatic granules ("hydrogenosomes") in Trichomonas vaginalis Donne from cultures in logarithmic and stationary growth.

Electron micrographs of Trichomonas vaginalis cells were examined morphometrically by means of an electronic image analyser. Cells from cultures in logarithmic growth contained smaller chromatic granules ("hydrogenosomes") and a higher proportion of sausage- or dumb-bell-shaped granules than did cells in stationary growth. These findings support the view that chromatic granules replicate by division of pre-existing granules and that this involves elongation and attenuation of their mid-region. The total area of cross sectioned granules occupied the same percentage of the cytoplasm of cells from cultures in logarithmic and stationary growth. The density of chromatic granules in the cytoplasm was identical for the two groups of cells.

Animals↗
PubMed1996

Human VEPs to isoluminant chromatic and achromatic sinusoidal gratings: separation of parvocellular components.

To extract the responses specific to the parvocellular system (color vision and form perception) in humans, visual evoked potentials (VEPs) in response to the onset of isoluminant chromatic (red-green) and achromatic (black-white) sinusoidal gratings were recorded in 15 young adults. Chromatic stimulation evoked a characteristic negative wave (N1) with peak latencies around 120 msec. The amplitude resembled an inverse U-shaped function against the spatial frequency with a peak at 2 c/deg. In contrast, VEPs to achromatic gratings showed different spatial frequency characteristics with a peak at 5.3 c/deg. With variations in the luminous intensity ratio between the red and green gratings, N1 was seen to respond maximally to isoluminant stimulation. These results indicate that the combined use of isoluminant chromatic and achromatic patterns could stimulate the parvocellular system selectively in humans.

Adult↗