Effects of chrysotile co-exposure on BaP binding in normal human fibroblasts

The effects of chrysotile and benzo(a)pyrene (BaP) co-exposure on uptake, metabolism and BaP binding to nucleic acids were investigated in normal human fibroblasts. A significant enhancement in these parameters was found when co-exposure was carried out under serum-free conditions. In the presence of serum, only a slight enhancement of BaP uptake was detected, while metabolism and binding to nucleic acids were not affected over the 8-hr incubation period studied.

Uranium and thorium isotopes and their state of equilibria in lungs from uranium miners

Radiochemical analysis of seven lungs obtained at autopsy show that concentrations ranged between 6 and 63 pCi/kg for 238U and 6-66 pCi/kg, for 234U. Similarly, 230Th ranged from 17 to 54 pCi/kg, two orders of magnitude higher than 230Th observed in the lungs of the general population from the Western mining region. For individual lungs, 238U and 234U were close to equilibrium with an average ratio of 238U/234U of 0.94 and a range of 0.80-1.02. Surprisingly, 230Th was close to equilibrium with 234U with a 230Th/234U ratio of 1.1 and a range from 0.54 to 2.6. Equilibrium between U and Th isotopes is in contrast to the disequilibrium reported in beagles which chronically inhaled carnotite, where the 230Th/234U ratio was observed to range from 5.4 to 7.4 with an average of 6.3. The average radiation dose rate to lung from each of the three radionuclides was calculated as follows: D = 18.7 CE where D = dose rate in mrad/year, C = activity concentration in tissue in pCi/g and E = energy absorbed per disintegration in MeV. The combined radiation dose rate (at death) due to three long-lived radionuclides 238U, 234U and 230Th varied from 2.5 to 14.2 mrad/yr with a mean of 9.6 mrad/yr. The concentration of 226Ra and daughters in the lung was not determined. An upper limit to the dose rate from the whole chain, calculated assuming 226Ra through 210Po are in equilibrium with 238U, 234U and 230Th, would be 30 mrad/yr.

Thorium concentration in human tissues from two U.S. populations

The concentrations of natural alpha-emitting isotopes of thorium (228Th, 230Th and 232Th) have been determined in 22 sets of human tissue samples obtained at autopsy from Grand Junction, CO and in 10 sets from Washington, DC. Tissues included lung, pulmonary lymph nodes, liver, kidney, bone, a few gonads, spleen and thyroid. Personal data on each individual's age, sex, smoking history and occupation were obtained whenever possible. The concentrations of 228Th, 230Th and 232Th were highest in lymph nodes for both populations with 2.6 and 5.1 pCi/kg of 228Th, 4.60 and 11.10 pCi/kg of 230Th, and 2.8 and 7.8 pCi/kg of 232Th in Washington, DC and Grand Junction, CO, respectively. The order of concentrations of all three isotopes in all other organs for both populations was as follows: (formula; see text) The data suggest that the non-mining residents who lived in the vicinity of uranium mine tailings do not have elevated 230Th concentrations in their lungs, when compared to the residents of Washington, DC who are not exposed to such tailings. However, 230Th concentration in bone of Grand Junction subjects was just significantly higher (at p less than 0.1) than that for Washington, DC subjects after suitable age adjustments. The data also suggest that 230Th is more available for accumulation in skeleton than would be supposed from its relative geochemical abundance.

The measurement of sister chromatid exchanges induced in utero utilizing intraperitoneal infusion of BrdU: a novel technique

One of the inherent difficulties associated with the accurate detection of sister chromatid exchanges (SCE's) in vivo is the maintenance of a continuous supply of 5-bromo-2'-deoxyuridine (BrdU) for differential staining of sister chromatids. We have developed a simple, reproducible intraperitoneal technique which has the advantages of continuous BrdU infusion and is less stressful than presently available methods. Additionally, a gentle trypsinization methodology was developed to obtain relatively large numbers of metaphases from fetal tissues. Using these techniques, we examined the induction of SCE by 7,12-dimethylbenz(a)anthracene (DMBA) when injected into pregnant CD rats on days 11, 13, 15, and 16 of gestation. The levels of SCE induced were slightly higher in fetal than maternal tissue, although not significantly.

Plutonium concentration in human tissues: comparison to thorium

The concentration of 238Pu, and 239,240Pu, and of 228Th, 230Th, and 232Th were measured in 10 sets of human tissues from Washington, DC, and 12 sets from Grand Junction, CO. The tissues were collected at autopsy by qualified pathologists from normal healthy persons most of whom died suddenly. The subjects had acquired plutonium from fallout of global nuclear testing and burnup of a space nuclear generator utilizing 238Pu. The median concentration of 239,240Pu was 0.08 pCi/kg in lung, 0.46 pCi/kg in tracheobronchial lymph nodes, 0.60 pCi/kg in liver, 0.02 pCi/kg in kidney and 0.17 pCi/kg in bone in Washington, DC subjects. Similarly, the concentration of 239,240Pu in Grand Junction subjects was found to be 0.17 pCi/kg in lung, 0.68 pCi/kg in lymph nodes, 0.55 pCi/kg in liver, 0.03 pCi/kg in kidney, 0.22 pCi/kg in bone and 0.08 pCi/kg in spleen. The median concentration in four gonads was 0.02 pCi/kg; the concentration in one thyroid was 0.01 pCi/kg. 238Pu was below the limit of detection in most organs except the liver where it ranged from 0.02 to 0.17 pCi/kg with a median concentration of 0.06 pCi/kg. The organ distribution pattern shows that most of the plutonium was accumulated in bone and liver with 54-60% in bone and 34-43% in liver. Only 3-6% was found in lung including lymph nodes; kidney, spleen, thyroid and gonads together contained around 1%. The analytical results show three major differences between plutonium and thorium concentrations and organ distributions: (1) for plutonium the liver is a major locus for storage (approximately 40% of that found in the total body), whereas little thorium is accumulated in the liver (around 4%); (2) the relative amounts of 230Th and 232Th are much higher in lung and lymph nodes (10-28%) than currently for plutonium (3-6%); (3) the ratio of throium concentrations in lymph nodes to lung is significantly higher than the ratio of plutonium concentration in lymph nodes to lung showing thereby that fallout plutonium is more soluble than natural thorium.

Growth characteristics of human glioma-derived and fetal neural cells in culture

Growth characteristics of human fetal neural cells (CH) and human glioblastoma multiforme-derived cells (12-18) in culture were compared. Cells were grown to confluent densities of 38,000 to 42,500 cells/cm2 for CH and 85,800 to 87,100 for 12-18. Population doubling times were 40.0 +/- 5.1 hr and 66.5 +/- 9.8 hr for CH and 12-18 cells, respectively. The mean DNA content per cell of the glioma-derived cells was twice that of the fetal brain cells at sparse, log, and confluent cell densities. High concentrations (40%) of serum in growth medium increased DNA contents in confluent CH, but not 12-18, cells. The amount of protein per cell also was consistently higher in glioma cells than CH cells, but, as cell densities increased, protein contents decreased for both: 1200 to 700 pg/cell in glioma cells, and 840 to 560 pg/cell in CH cells. In each cell line, initial rates of [3H]ThdR incorporation into TCA precipitable material decreased as cell density increased, but confluent glioma-derived cells incorporated 10 times more [3H]ThdR than confluent fetal cells. Almost all CH cells had a normal diploid chromosome number of 46. A histogram showing the relative frequencies of chromosome numbers of glioma-derived cells had peaks of 52, 79, and 105 chromosomes per metaphase, indicating a haploid number of 26 for most cells. Lengths of cell cycle phases, determined using autoradiographic techniques, indicate that glioma-derived cells had a longer generation time and S period than fetal neural cells. These data demonstrate several biological differences between glioblastoma-derived cells and non-neoplastic fetal neural cells, indicating that this system is of potential value for comparative studies on growth control and contact inhibition.

Intake of magnesium and toxicity of lead: an experimental model

Groups of ten male Wistar rats were fed 100 mg lead/kg body wt . day, or 100 mg lead plus 250 mg Mg . kg body wt . day mixed in the powdered diet as chlorides. Blood and urine were monitored for lead-related enzymes and lead concentrations. Compared to the lead-treated, blood lead and urinary aminolevulinic acid were much lower and blood aminolevulinic acid dehydratase and urinary lead were higher at 30, 45, and 62 days in the lead-magnesium-treated animals. At 45 and 62 days, blood lead was higher in the lead-magnesium group even though the urinary excretion of lead was significantly higher (P less than .01). At 62 days, the lead feeding was discontinued to both groups, but magnesium administration was continued. Both groups of rats were then monitored for urinary excretion of lead and this was significantly higher (P less than .01) in the rats fed magnesium suggesting that magnesium intake helped mobilize lead from bone, thus increasing the blood lead level and subsequent urine excretion. Enzyme levels approached normal values at 106 days only in the lead-magnesium group, thereby indicating low levels of lead toxicity. Lead levels of bones in rats of the lead-magnesium group, when sacrificed at 106 days, were significantly lower (P less than .01) than among those given lead alone, another indication that magnesium helped mobilize lead from bone. The results, therefore, clearly show that feeding magnesium leads to lower retention and increased excretion of lead under the experimental conditions outlined.

Paragonimus westermanni in tigers (Panthera tigris) in India

Paragonimus westermanni was found in the lungs of two young tigers (Panthera tigris). Cysts were focally distributed in the lungs, initiating an emphysematous response together with extensive fibrosis in the vicinity of the cysts.

Potentiation of langat virus infection by lead intoxication--influence on host defenses

Pathogenesis was studied in mice with moderate levels of lead intoxication after Langat virus infection. Both lead chloride and lead nitrate increased mortality by 40--50%. This increase was associated with decreased in vivo interferon and neutralizing antibody synthesis. The increased mortality was associated with enhancement of viral growth in peripheral tissues as evidenced by early appearing and long-lasting high titer viremia following lead intoxication. This resulted in early penetration of blood brain barrier and led to much higher virus titers in the brain. The data strongly suggest that lead increased mortality following infection by complex means, the most important being the enhacement of encephalitogenic potential of Langat virus.

The coefficients of the Jones-Dole equation for the viscosity of solutions of potassium iodide in mixtures of water and dimethylacetamide at 35°C

The viscosities of solutions of KI in binary mixtures of water and dimethylacetamide at 35�C in the concentration range 0.005-0.2 mol dm-3 are reported. The data are analysed in terms of the A and B parameters of the Jones-Dole equation. The value of the B coefficient first decreases and then increases after attaining a minimum at about 0.05 mole fraction of dimethylacetamide.

Lead content of tissues of baby rats born of, and nourished by lead-poisoned mothers

Three groups of Wistar rats (5 males and 5 females in each group) were given zero, 100 mg., and 200 mg. Pb(NO3) 2 per kilogram of body weight per day for 45 days and were mated. The lead feeding was continued throughout the duration of experiments. The blood and urinary lead, blood aminolevulinic acid dehydratase activity, and free erythrocyte protoporphyrin and urinary aminolevulinic acid were measured on these rats at the beginning of the study, at the time of mating, and prior to delivery. The tissues, incuding kidney, liver, heart, and brain of the newborn progeny were analyzed for lead content. The blood lead and aminolevulinic acid dehydratase were also measured (pooled blood). These tissues contained very high amounts of lead when the newborns were killed within half an hour after their birth, a very significant reduction being found after one day with further reduction after 7 days. Kidney and heart contained the highest amount of lead, the levels being dose-related. Three weeks after birth the lead content of tissues rose significantly but blood concentrations remained almost identical to the levels obtained 1 day after birth. There was no evidence of lead accumulation in the brain of the babies...

Distribution of thallium and lead in children's blood

Mean whole blood concentrations for lead and thallium were determined by atomic absorption spectrophotometric analysis for children residing in Newkark, NJ. Frequency distributions for the various concentration ranges for both metals were recorded. There is no noticeable correlation between the lead and thallium content of whole blood, which suggests that exposure to and/or absorption of these substances are different.

Extraction of lead from printed matter at physiological values of pH

In an in vitro laboratory study of the extractability of lead in printed matter it was found that dangerous quantities of lead, up to 200 mug, could be extracted from "small" pieces of printed paper at pH values in the range of human gastric fluid. Lead was not extracted at pH values in the range of human saliva. Children who chew printed matter may not be in danger of absorbing lead, but the pica-prone child who swallows printed material may be at risk of absorbing excessive amounts of this toxic metal. The use of printing inks containing high-lead levels should be discouraged.

Kinetics and mechanism of the osmium tetroxide catalysed oxidation of tartrate and malate ions with alkaline ferricyanide

The alkaline ferricyanide oxidations of tartrate and malate ions have been studied in the presence of osmium tetroxide used as catalyst. The rates are consistent with a mechanism involving as the first step the formation of a 1 : 1 complex of osmium(v111) and the anion of the organic acid followed by decomposition to intermediate products and the osmium(v1) species with hydroxide ion. The osmium(V1) thus produced is rapidly oxidized to osmium(V111) with ferricyanide. The kinetic data obtained at higher tartrate concentrations indicate the formation of an osmium(v111)-(tartrate)2 complex that is resistant to decomposition. The possibility of the formation of osmium(V1)-organic anion complexes, causing a retarding effect on the reaction velocity during a kinetic run, is also discussed. The oxidation products are determined and a possible set of reactions for their formation is set out.

Kinetics and mechanism of the osmium-tetroxide-catalysed oxidation of mandelate ion by hexacyanoferrate(III) ion

The osmium-tetroxide-catalysed oxidation of mandelate ion by hexacyanoferrate(111) ion has been studied kinetically. The reaction rate has been found to be independent of hexacyanoferrate(111) ion while the order with respect to both osmium tetroxide and mandelate ion comes out to be unity. The reaction rate follows first-order kinetics at low hydroxyl ion concentration and becomes zero order at higher concentrations. The course of the reaction has been considered to proceed through the formation of an activated mandelate-OsO4, complex which decomposes in alkaline medium giving reduced osmium(V1) followed by a fast oxidation by hexacyanoferrate(111) ion. The probable course of the reactions is also described with the help of its oxidation product, benzoic acid.