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PubMed1996

Pleuroperitoneal migration of intraperitoneal phosphorus-32-chromic phosphate therapy for stage I ovarian carcinoma.

A patient with postoperative Stage I ovarian carcinoma received 15 mCi of 32P-chromic phosphate suspension in normal saline intraperitoneally as part of her therapy. The following day, a portion of the infused radiopharmaceutical and normal saline had passed transdiaphragmatically into the patient's right pleural cavity. Thoracentesis removed as much fluid as possible and this fluid contained radioactive material. In the ensuing 4 yr, the patient has not manifested any detectable pleural or pulmonary abnormalities attributable to the radioactivity. Retrospective review of 100 consecutive patients receiving 32P-chromic phosphate intraperitoneal therapy resulted in 43 patients in whom the hemithoraces could be evaluated scintigraphically. Three of the 43 patients (7%) had right pleural fluid radioactivity. This is similar to the percentages reported in patients with cirrhosis with ascites in whom hepatic hydrothorax is identified.

Chromium Compounds↗
PubMed1996

Body contour determination and validation for bremsstrahlung SPECT imaging.

UNLABELLED: The purpose of this study was to validate a previously reported body contour measurement using Compton backscatter sources with bremsstrahlung SPECT imaging. METHODS: Bremsstrahlung SPECT imaging was performed with 32P using a dual-headed camera system fitted with medium-energy, parallel-hole collimators. Two sources of 99mTc were placed directly on each collimator. Energy windows of 100 keV +/- 25% were used to image the 32P and also to record the Compton scatter from the 99mTc sources. Eleven patients enrolled in clinical Phase I therapeutic protocols were injected with 32P-chromic phosphate and SPECT images were acquired and reconstructed in the transaxial plane. The 32P distribution and the patient body contour were both visualized in these slices. The anteroposterior and lateral patient dimensions were measured by generating count profiles parallel to the anteroposterior and lateral body contour, respectively, at the midline in a transaxial slice. The distance in centimeters between the two centroids of each profile is representative of the anteroposterior and lateral dimensions and was determined for each patient. These anteroposterior and lateral dimensions were compared to the same distance measurements made in these patients by CT in an anatomically comparable transaxial slice. A cylindrical SPECT phantom was also studied to further validate the contour measurements. RESULTS: The mean percent difference in the patient dimension measurements between SPECT and CT was -0.8% with a range of -8.5% to 9.9%. The percent difference between the known and SPECT measured dimensions in the cylindrical phantom was 0.5%. CONCLUSION: The two external Compton scatter source method is accurate for determining the body contour.

Chromium Compounds↗
PubMed1996

Great particles [32P]chromic phosphate for treatment of solid tumors.

With the purpose of studying the effectivity of an intratumoral single dose of chromic [32P] phosphate with great particles for the treatment of solid tumors, studies of bioelimination, biodistribution and therapeutic action were carried out. Only for comparative purposes, similar studies were undertaken using a solution of sodium -32P- orthophosphate-gelatine. The results show that when sodium [32P] orthophosphate-gelatine is used, the percentage of total elimination is (85.90 +/- 8.70)% with a higher percentage in urine (64.50 +/- 13.70)% than in faeces (21.40 +/- 4.50)%. In biodistribution studies, the greater percentage is found in bone (15.54 +/- 2.21)% while only a (2.51 +/- 0.39)% remains in the tumor. When great particles chromic [32P]phosphate was intratumorally injected, we determined that the total elimination is equal (36.28 +/- 6.27)%, finding a higher amount in faeces (29.44 +/- 5.26)% than in urine (6.84 +/- 2.21)%. Biodistribution studies demonstrated that (49.82 +/- 5.41)% remains in the tumor and (9.63 +/- 4.89)% of the injected activity is found in the liver. On the other hand, when therapeutic action was evaluated, we observed that the percentage of tumor regression (P.T.R.) is 52.0% for the tumors injected with chromic [32P]phosphate and 0.0% for those injected with sodium [32P]orthophosphate-gelatine. These results show that the great particles colloid of chromic [32P]phosphate is not safe enough for the treatment of solid tumors, since it is mobilized from the injection point, delivering a high dose to the whole organism.

Adenocarcinoma↗
PubMedDate not supplied

Shear bond strength of Rexillium III to enamel using resin composite cements.

This study evaluated the shear bond strength of Rexillium III (Jeneric Pentron, Wallingford, CT) to enamel using various resin composite luting systems. Cast alloy cylinders (3.9 mm X 6.0 mm) were bonded with each cement to human molar buccal enamel surfaces (n = 8). The enamel was etched using a 35% phosphoric acid solution for 30 seconds. Bonded specimens were stored in distilled water for 7 days at 37 degrees C and thermocycled (1,500 cycles) in 5 degrees C and 55 degrees C water baths (1-minute dwell time). Specimens were randomly tested in shear using a crosshead speed of 0.5 mm per minute. Use of a one-way analysis of variance (P < .001) and Ryan-Einot-Gabriel-Welsh multiple range test showed significant differences between several of the resin cements. Panavia exhibited a significantly higher shear bond strength than any of the other cements tested.

Analysis of Variance↗
PubMedDate not supplied

Dissolution of stainless steel in artificial saliva.

Dissolution of stainless steel type 304 in artificial saliva was studied by electrochemical methods, electron spectroscopy for chemical analysis, and atom absorption spectroscopy. The samples were polarized in the -400 mV (saturated calomel electrode) to -50 mV (saturated calomel electrode) range. The total thickness of the passive film was found to be 25 +/- 3 A, independent of the potential. The passive film consists of a duplex structure: an inner layer of (Cr0.5Fe0.5)2O3 and an outer layer of a mixture of Cr(OH)3 and (CrxFey)PO4.2H2O. The analysis indicated that 11 micrograms/cm2 of the alloying elements were dissolved during exposure for 1 year.

Chromium Compounds↗
PubMed1997

Coconut oil as a protective carrier of dietary vitamin A fed to ruminants.

Safflower and coconut oil were compared as protective carriers of dietary vitamin A supplemented to abomasally cannulated sheep. Vitamin A, 240,000 I.U., was predissolved in 11.7 g of safflower or coconut oil and bolused directly into the rumen of mature wethers along with 4 g of chromic oxide. The vitamin A was pre-dissolved in 0, 11.7, 23.4 or 35.0 g of coconut oil in experiment 2. Determination of carrier oil protectiveness of solubilized dietary vitamin A was based on recoveries of vitamin A supplement and chromic oxide in abomasal digesta 24 h post dosage. Vitamin A recoveries were significantly higher (P < 0.05) when dissolved in coconut oil (55.6%) compared to safflower oil (35.5%). Recoveries of vitamin A in abomasal digesta increased linearly (P < 0.01) with the amount of carrier coconut oil in experiment 2. Results of these experiments support the potential use of coconut oil as a protective carrier of ruminal labile vitamin A.

Animals↗
PubMed1996

The somatic white-ivory eye spot test does not detect the same spectrum of genotoxic events as the wing somatic mutation and recombination test in Drosophila melanogaster.

A groups of six chemical compounds was tested in parallel in two different somatic genotoxicity assays in Drosophila melanogaster, the wing somatic mutation and recombination test (SMART) and the white-ivory eye spot test. The wing spot test makes use of the wing cell markers multiple wing hairs (mwh) and flare (flr) and detects both mitotic recombination and various types of mutational events. The white-ivory eye spot test makes use of the white-ivory (wi) quadruplication and detects the somatic reversion of the recessive eye color mutation wi to the wild-type (w+). Three- or two-day-old larvae were fed chronically with the compounds ethylnitrosourea (ENU), N-nitrosopyrrolidine (NNP), caffeine (CAF), chromium (VI) oxide (CRO), potassium chromate (POC), and 2,4-dichlorophenoxyacetic acid (2,4-D). All six compounds are genotoxic to various degrees in the wing spot test. The percentage of the genotoxic activity that is due to mitotic recombination was between 84% and 91% for the hexavalent chromium compounds CRO and POC and about 68% for 2,4-D. In contrast, ENU and NNP showed only 46% and 25% recombinagenic activity, respectively. In the white-ivory eye spot test, the three compounds (CRO, POC, and 2,4-D) with high recombinagenic activity and CAF were clearly nongenotoxic, whereas only ENU and NNP gave a positive response. From these results, it is concluded that the spectrum of genotoxic events detected by the two assays is different. In particular, the white-ivory eye spot test appears not to detect mitotic recombination the way the wing spot test does.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2000

Chemoselective C-H oxidation of alcohols to carbonyl compounds with iodosobenzene catalyzed by (salen)chromium complex

Primary and secondary alcohols with benzylically and allylically activated C-H bonds are chemoselectively oxidized to the corresponding carbonyl compounds by the (salen)Cr(III) complex I as the catalyst and iodosobenzene as the oxygen source; the oxidizing species is the Cr(V) oxo complex. Allylic alcohols with fully substituted double bonds give appreciable amounts of epoxides besides the C-H oxidation products enones, while saturated alcohols are less readily oxidized.

Journal Article↗
PubMed1992

Production of 8-hydroxydeoxyguanosine in isolated DNA by chromium(VI) and chromium(V).

Chromium(VI) and Cr(V) compounds increased the concentration of 8-hydroxydeoxyguanosine (oh8dG) in isolated DNA, whereas no such increase was seen with Cr(III). Furthermore, incubating DNA with H2O2 and Cr(VI) or Cr(V) potentiated the formation of oh8dG above levels observed with either chromium compound alone. In the presence of catalase, the increase in DNA oxidation observed with Cr(VI) was inhibited, the base oxidation observed being equivalent to background levels, and this indicated involvement of H2O2 in the mechanism. Glutathione did not enhance chromium-induced formation of this oxidized base. These results help to explain a mechanism of chromium-induced DNA oxidation involving H2O2 via a Fenton-type reaction.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2004

Ferromagnetic ordering in bis(benzene)chromium(+) Bis(4,5-dimethoxybenzene-1,2-dithiolato)nickel(-).

The compound bis(benzene)chromium(+) bis(4,5-dimethoxy-1,2-benzenedithiolato)nickel(-), [Cr(bz)(2)](+)[Ni(dmox)(2)](-), was prepared as well-defined crystals by a metathesis reaction. X-ray single-crystal structure confirms the expected symmetries of the cations (D6h) and anions (D2h). The Ni-S bond length is typical for a monoanionic bis(arene)-1,2-dithiolato nickel complex thus confirming the ascribed charges. The structure reveals interpenetrating cation and anion sublattices where all ions are well separated from other ions of the same charge and with almost perpendicular symmetry planes of cations and anions. Above ca. 10 K the compound is paramagnetic and follows the Curie-Weiss law for S = 1/2 on each ion with a Weiss temperature of 8.5 K. Magnetic susceptibility and magnetization studies reveal the transition to a ferromagnetically ordered phase at 3.4 K. The ferromagnetic interaction is likely to occur through short contacts between anion heteroatoms (O and Ni) and cation H atoms, forming a 2-D network. A third dimension is possible through somewhat longer interionic S-H contacts. The Curie-Weiss law behavior can be modeled for 1-D chains with a ferromagnetic interaction of J = 11.6 K.

Journal Article↗
PubMed2000

Tricarbonyl[(6a,7,8,9,10a-eta)-3,3-dimethyl-3H-benzo[f]chromene]chromium.

The title compound, [Cr(C(15)H(14)O)(CO)(3)], is a chromene complexed with tricarbonylchromium and it exhibits photochromic properties. The molecular geometry is compared to that of two similar complexes. The analysis results indicate that complexation has minor effects on the chromene structure.

Journal Article↗
PubMed2003

Tricarbonyl(eta6-chlorobenzene)chromium.

The title compound, [Cr(C(6)H(5)Cl)(CO)(3)], is the first group 6 tricarbonyl eta(6)-monohaloarene compound to be structurally characterized. It adopts a classic piano-stool structure, with the Cr(CO)(3) tripod assuming a syn-eclipsed conformation relative to the arene ring (varphi = 2.0 degrees ). The extended structure is dominated by intermolecular pi.H interactions (H.ring centroid = 2.94 A) and non-classical hydrogen bonds between carbonyl and arene moieties (O.H = 2.50-2.58 A).

Journal Article↗
PubMed2004

Biological treatment of tannery wastewater in the presence of chromium.

Experiments were carried out to determine the feasibility of treating tannery wastewater containing chromium, an inhibiting compound, with sequencing batch reactors (SBR). The maximum chromium concentration tolerated by microorganisms was determined through aerobic and anoxic batch experiments, and the biomass inhibition process was analyzed in a lab scale reactor at increasing chromium concentrations. The results obtained, in batch experiments and in the SBR reactor, have demonstrated that chromium addition had less influence on the denitrification bacteria than on the nitrification bacteria. In addition, it was observed that nitrification and denitrification rates, at the same chromium concentration, were higher in the SBR reactor than in batch experiments with unacclimated biomass. Experimental results confirm that sequencing batch reactors are able to produce a more resistant biomass, which acclimates quickly to inhibiting conditions. A large amount of chromium was found in the sludge from the reactor, while the effluent was devoid of the inhibiting metal.

Biodegradation, Environmental↗
PubMed1998

Chromium(III) decreases the fidelity of human DNA polymerase beta.

Certain particulate compounds of hexavalent chromium are well-known occupational and environmental human carcinogens. Hexavalent chromium primarily enters the cells and undergoes metabolic reduction; however, the ultimate trivalent oxidation state of chromium, Cr(III), predominates within the cell. DNA-bound Cr(III) has been previously shown to decrease the fidelity of replication in the M13 phage mutation assay. This study was done to understand how Cr(III), in the presence of physiological concentrations of magnesium, affects the kinetic parameters of steady-state DNA synthesis in vitro across site-specific O6-methylguanine (m6dG) residues by DNA polymerase beta (pol beta). Cr(III) binds to the short oligomer templates in a dose-dependent manner and stimulates the activity of pol beta. Cr(III) stimulates the mutagenic incorporation of dTTP opposite m6dG more than the nonmutagenic incorporation of dCTP, and thereby Cr(III) further decreases the fidelity of DNA synthesis across m6dG by pol beta. In contrast, Cr(III) does not affect the fidelity of DNA synthesis across the normal template base, dG. Both the enhanced activity and the mutagenic lesion bypass in the presence of Cr(III) may be associated with Cr(III)-dependent stimulation of pol beta binding to DNA as reported here. This study shows some of the mechanisms by which mutagenic chromium affects DNA synthesis.

Binding Sites↗