Activity of glutamate decarboxylase in the brain of rats exposed to carbon disulfide

Summary The activity of glutamate decarboxylase in the brain of white rats exposed to CS₂ was measured. The lower activity of the enzyme in rats intoxicated with CS₂ was parallel to the decreased level of -aminobutyric acid. Pyridoxal phosphate did not prevent inhibition of the enzyme activity. It is suggested that the inhibition of the activity of glutamate decarboxylase by CS₂ is responsible for lower level of -aminobutyric acid in the brain of rats intoxicated with CS₂.     

Blood acetaldehyde in alcoholized rats and humans during inhalation of carbon disulphide vapor

Summary Exposure of rats to 20 ppm CS₂ (the current MAC in various countries) for 8 h was followed by i.p. administration of 2 g/kg ethanol (blood level: 3-1) and another up to 4-h exposure to the same concentration of CS₂. During the second exposure the acetaldehyde concentration increased significantly, the rise representing one third of the control values. Inhalation of 400 ppm CS₂ for the same period, or 8-h exposures at 400 ppm CS₂ on 5 consecutive days produced only a slight additional increase in acetaldehyde. The increased appearance of acetaldehyde in blood is considered to be due to inhibition of aldehyde dehydrogenase by CS₂. This conclusion was derived from the significant lag in the clearance rate of acetaldehyde given i.v. (1 mmol/kg) after exposure at 400 ppm CS₂/8 h, involving an increase of the excretion half-life of acetaldehyde (1 min, 45 s in the controls) to 2 min, 24 s. The finding thus obtained could be reproduced in man (adult males). At a blood alcohol concentration of approximately 0.75, maintained at this level for 8 h, the blood acetaldehyde concentration was found to be approximately 6 × 10^–3; it rose significantly by about 50% during simultaneous 8-h exposure of the test subjects to a nonfluctuating, analytically defined concentration of 20 ppm CS₂. When increasing the dose Of CS₂ to 40 ppm and 80 ppm for 8 h, only a slight additional increase was noted. Administration of ethanol (ca. 0./5) for 8 h, instituted at 16 h after 8-h inhalation of 20 ppm CS₂, produced a rise in blood acetaldehyde to slightly more than twice the control value. An approximately identical quantitative effect was observed after exposure to 20 ppm on 5 consecutive days at the same time of the day (8.00 a.m. - 4.00 p.m.). Under the conditions employed, there was no evidence of any subjective or objective signs of alcohol intolerance in terms of an antabuse syndrome in the experiments. Inhalation of CS₂ vapor failed to exert a significant effect on the pharmacokinetic behavior of ethanol in with a blood alcohol content up to 0.8%., contact with CS₂ is not likely to give rise to a CS₂-alcohol reaction, provided the concentrations of CS₂ encountered in the work environment are within the range of the MAC.     

Detection of carbon disulfide in breath and air: a possible new risk factor for coronary artery disease

Summary Carbon disulfide (CS₂) is toxic to the heart and arteries; chronic exposure can result in accelerated atherosclerosis and coronary artery disease in humans and animals. Exposure to CS₂ was investigated in normal volunteers working in New York City, using a new and highly sensitive assay. Volatile organic compounds in breath and air were captured in adsorbent traps containing graphitized carbon and molecular sieve, then thermally desorbed, concentrated by two-stage cryofocusing, and assayed for CS₂ by gas chromatography/mass spectroscopy. Breath CS₂ assays were performed in 42 normal volunteers, as well as in room air and in outdoor air collected at sites in and around New York City. The assay was linear, reproducible, and sensitive to picomolar (10^–12 mol/l) quantities. CSZ was detected in all samples of breath and indoor and outdoor air (mean concentrations were 5.25 pmol/l, SD = 3.89 in breath, 8.26 pmol/l in indoor air, and 3.92 pmol/l in outdoor air) (NS). The alveolar CS₂ gradient (alveolar — inspired CS₂) ranged from –20.0 to 8.0 nmol/l, separating subjects into either excreters or retainers of CS₂. In view of the known toxicity of CS₂, atmospheric pollution with CS₂ merits attention as a possible new risk factor for the development of accelerated atherosclerosis and coronary artery disease.     

Absorption,metabolism and elimination of N,N-dimethylformamide in humans

Summary Excretion of N,N-dimethylformamide (DMF) and DMF metabolites N-hydroxymethyl-N-methylformamide (MF), N-hydroxymethyl-formamide (F) and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) has been monitored in the urine of volunteers during and after their 8-h exposure to DMF vapour at a concentration of 10, 30 and 60 mg · m^–3. The pulmonary ventilation in these experiments was typically about 101 · min^–1 and the retention in the respiratory tract was 90%. After exposure to 30 mg DMF · m^–3, the yield of compound determined in the urine represented 0.3% (DMF), 22.3% (MF), 13.2% (F) and 13.4% (AMCC) of the dose absorbed via the respiratory tract. The excretion curves of the particular compounds attained their maximum 6–8h (DMF), 6–8h (MF), 8–14h (F) and 24–34h (AMCC) after the start of the exposure. The half-times of excretion were approximately 2, 4, 7 and 23 h respectively. In contrast to slow elimination of AMCC after exposure to DMF, AMCC was eliminated rapidly after AMCC intake. This discrepancy could be explained by rate-limiting reversible protein binding of a reactive metabolic intermediate of DMF, possibly methylisocyanate.     

Identification by physical means of organic moieties of conjugates produced from carbaryl by tobacco cells in suspension culture

Carbaryl (1-naphthyl methylcarbamate), labeled with¹⁴C in the C₁-naphthyl, carbonyl, orN-methyl position, was introduced into the culture medium of tobacco cells in suspension culture. Following incubation, cells were homogenized in water, centrifuged, and supernatants hydrolyzed with-glucosidase or HCl. Organic moieties (moieties) were characterized by two-dimensional thin-layer chromatography (TLC), and many were subsequently identified by infrared and mass spectrometry. On the basis of the data obtained with¹⁴C₁-naphthyl-labeled carbaryl, it appeared that 18.4% of the total characterized metabolites represented unconjugatedN-CH₂OH- carbaryl [1-naphthylN-(hydroxymethyl)carbamate], excreted by the cells into the culture medium. The metabolites found in the cells primarily consisted of conjugates of 1-naphthol (73.6% of the total characterized metabolites) andN-CH₂OH-carbaryl (2.5%). Conjugates of 7-hydroxycarbaryl (7-hydroxy-1-naphthyl methylcarbamate), 4-hydroxycarbaryl (4-hydroxy-1-naphthyl methylcarbamate), and 5-hydroxycarbaryl (5-hydroxy-1-naphthyl methylcarbamate) were also detected in small amounts. Of five unknown¹⁴C₁-naphthyl-labeled carbaryl metabolites, three were tentatively characterized as:O-1-naphthylcholesterol (cholest-5-en-3-yl-1-naphthol; 3.0%); an unconjugated hydroxylated 1,4-dihydro-1,4-epiperoxynaphthalene (1.4%); and an acidlabile,-glucosidase-resistant conjugate of acis-dihydrodiol of 1-naphthol (0.3%; other than thetrans-5,6-dihydrodiol). The cholesterol derivative may represent a new detoxification mechanism in plants; the epiperoxide may help to elucidate plant oxidation mechanisms. A new TLC procedure was developed which successfully separated the acetate derivative ofN-hydroxycarbaryl (1-naphthylN-hydroxy-N-methylcarbamate) from 12 other common moieties of carbaryl metabolites and their acetate derivatives. A new two-dimensional TLC system was developed for the separation of underivatizedN-hydroxycarbaryl from 14 other moieties of carbaryl metabolites; two additional two-dimensional TLC systems were utilized for moiety separations. With these TLC procedures, no conjugated or unconjugatedN-hydroxycarbaryl could be detected in any tobacco cell culture fraction after incubation of cells in medium containing radiolabeled carbaryl. Authentic¹⁴C₁-naphthyllabeledN-CH₂OH-carbaryl was shown to be converted to desmethylcarbaryl (1-naphthylcarbamate) (97%) and 1-naphthol (3%) by 0.1N HCl hydrolysis.Deceased.     

Nitrous oxide in blood and urine of operating theatre personnel and the general population

Nitrous oxide (N₂O) was assayed in 676 urine samples and 101 blood samples provided after exposure by operating theatre personnel from nine hospitals. The blood and urine assays were repeated in 25 subjects 18 h after the end of exposure. For 80 subjects, environmental N₂O was also measured during intraoperative exposure. Mean urinary N₂O in the 676 subjects at the end of exposure was 40 g/l (range 1–3805 g/l); in 10 of the 676 subjects, urinary N₂O was in the range 279–3805 g/l (mean 1202 /l). The 98^th percentile was 120 g/l. Mean blood N₂O at the end of exposure, measured in 101 subjects, was 21 g/l (median 16 g/l, range 1–75 g/l). Blood and urine N₂O (1.5 g/l and 4.9 g/l, respectively) in 25 subjects, 18 h after exposure, was significantly higher than in occupationally non-exposed subjects (blood 0.91 g/l, urine 1 g/l). Environmental exposure was significantly related to blood and urinary N₂O (r = 0.59 andr = 0.64, respectively). Blood and urinary N₂O were significantly related to each other (r = 0.71), and were equivalent to about 25% of the environmental exposure level. The mean urinary N₂O of 1202 g/l in 10/676 subjects was not related to environmental exposure in the operating theatre. The highest urinary N₂O levels measured in these 10/676 subjects could be explained by an asymptomatic urinary infection.     

Changes in activity of malate dehydrogenase and glucosephosphate isomerase in serum of rats exposed chronically to inorganic mercury and its aryl and alkyl compounds

Summary In course of prolonged exposure /14 weeks/ to various mercury compounds /MetHg — a fluid seed-dressing preparation 0,8, Phenyl and Ethyl chlorides and.HgCl₂ in doses corresponding to 5% of DL₅₀/3 times weekly/, enhanced levels of activity of malate dehydrogenase /MDH/ and glucosephosphate isomerase /PHI/ in blood serum were observed. After 7 weeks of exposure about fourfold increase of MDH and 2-3-fold enhancement of PHI activities were found relative to controls. After 14 weeks of exposure in livers of rats, given MetHg and EtHg, organic mercury was found at concentrations of 28,8 and 4 g/g tissue, respectively. Inorganic mercury in liver was found in animals given all compounds and concentrations were in the range of 1,2 – 4,7 g/g tissue.The study was partly subsidised by the Polish-American agreement 05-009-2 with the National Institute of Occupational Safety and Health, PHS, USA. Chief investigator — doc. dr hab. O.K. Piotrowski.     

The effects of salinity on pentachlorophenol accumulation and elimination by killifish (Oryzias latipes)

Fresh water and seawater acclimated (FWA and SWA) killifish (Oryzias latipes) were exposed to pentachlorophenol (PCP) at various salinities (1.2–18.7). The PCP accumulation in the fish decreased with increase of salinity. As the salinity increased [0 (freshwater) –18.6], the PCP clearance rate increased from 0.0097 to 0.0170 (h^–1). A substantial increase of the clearance rate was observed when the salinity was over 9.3. The PCP uptake rate decreased from 20.8 to 10.6 (ml^–1 g^–1 fish h^–1) with the increase of salinity. The uptake rate decreased at a lower salinity (4.7). The excretion of PCP glucuronide (PCP-G) increased markedly at the salinity of 9.3, although that of PCP sulfate (PCP-S) did not change. The increase of PCP-G excretion may correspond to the increase of clearance rate. Abrupt transfer of FWA and SWA killifish to a PCP solution with a different salinity decreased the PCP accumulation and increased the PCP metabolite excretion with the increase of the salinity. However, the amount of PCP accumulated by FWA was greater than that by SWA killifish.     

Platelet aggregation,thromboxane production and thrombogenic ratio in postmenopausal women consuming high oleic acid-sunflower oil or palmolein

Summary. Background: Saturated fatty acids exert controversial effects on platelet aggregation and eicosanoid production. Aim: To investigate the effect of a dietary exchange between palmitic acid and oleic acid on both platelet aggregation and thromboxane B2 (TXB₂) production, and on urine TXB₂, prostacyclin I2 (PGI₂ as 6-keto-protaglandin F₁), and the thrombogenic ratio (TXB₂/6-keto-protaglandin F₁) in fourteen postmenopausal women. Experimental design: Women were assigned to two consecutive 28-d dietary periods that were high in cholesterol (~400 mg/d) and fat (~46%en). In the first period all subjects followed an oleic acid-rich diet prepared with high oleic acidsunflower oil. This was followed by a second period rich in palmitic acid in the form of palmolein. Determinations: Nutrient intakes, ADP-platelet aggregation, platelet TXB₂ production, urine TXB₂ and 6-keto-protaglandin F₁ were measured during two dietary periods and the results obtained correlated to serum cholesterol, lipoproteincholesterol and peroxides, apolipoproteins and plasma tocopherol. Results: The palmolein diet led to an increase in the platelet aggregation rate (p < 0.05) and in the time for the maximal aggregation rate (p < 0.02).No significant differences were observed in platelet TXB₂ production. Palmolein increased urine TXB₂ in pg/mL (p < 0.05) and pg/min (p < 0.01), whereas the thrombogenic ratio (TXB₂/6-keto-protaglandin F₁) did not change. Most changes were related to oil change, few to serum cholesterol level (< or 6.2 mmol/L) or age (< or 65 yr). Conclusions: Palmolein diet activates platelet aggregation more in normocholesterolemics. Though palmolein increased thromboxane and tended to increase prostacyclin in urine in normo- and hypercholesterolemic women, the thrombogenic ratio did not change. These effects were related to the LDL and HDL concentration increases and to the absence of change in the total cholesterol/HDL-cholesterol ratio found following the dietary intervention.     

Aortic phospholipids synthesis in experimental carbon disulphide intoxication in rats

Summary The rate of incorporation of phosphate precursor into phospholipids in vivo has been investigated in normal rats and in those intoxicated with CS₂. The specific activity of ³²p phospholipids was measured in plasma and the aorta wall at various times after i.v. administration of 0.2 mCi phosphate.In CS₂ intoxicated rats the specific activity of aorta phospholipids exceeded that in normal rats. The conclusion is drawn that the rise of the aortic phospholipids specific activity does not derive from increased blood phospholipid concentration but is due to an increased rate of phospholipids synthesis in the aorta tissue.This investigation has been done under the Polish-American agreement No 05-008-2 with the Occupational Health Program, U.S. Public Health Service.     

Experimental human exposure to carbon disulfide

Summary Six human volunteers were exposed to 10 and 20 ppm carbon disulfide at rest and to 3 and 10 ppm carbon disulfide under a 50 W level of physical exercise during four consecutive periods of 50 min. At the start of the experiments, at the end of the exposure periods and during the post-exposure period, urine was sampled and the concentration of 2-thiothiazolidine-4-carboxylic acid (TTCA) was determined. It was established that only a small percentage, ranging from 0.7 to 2.2% of the absorbed carbon sulfide was transformed into TTCA. The excretion rate of TTCA (mol TTCA h^–1) was found to be the best parameter in evaluating the respiratory uptake of carbon disulfide over a range of 37.9 to 163.3 mg CS₂ compared to the urinary concentration of TTCA (mole TTCA ml^–1) or the creatinine corrected concentration of TTCA (mmol TTCA mol^–1 creatinine). The total amount of TTCA (mol TTCA) excreted proved to be independent of the urinary flow (ml h^–1), the estimates of the individual fatty tissue content and the urinary pH. No correlation was found between the respiratory uptake of carbon disulfide (mg CS₂) and the excretion rate of TTCA within each exposure condition of 3, 10 or 20 ppm carbon disulfide, respectively.     

Heavy Metals (Cr, Zn, Ni, V, Pb, Cd) in Lingonberries (Vaccinium vitis-idaea L.) and Assessment of Human Exposure in Two Industrial Areas in the Kemi-Tornio Region, Northern Finland

The concentration of Cr, Zn, Ni, V, Pb, and Cd were measured in lingonberries (Vaccinium vitis-idaea L.) sampled at 23 sampling sites around a ferrochrome and stainless steel works and opencast chromium mine in the Kemi-Tornio region, Northern Finland. Two different microwave-assisted digestion procedures were used for sample digestion, i.e., a mixture of HNO₃ + H₂O₂ and a mixture of HNO₃ + H₂O₂ + HCl + HF + H₃BO₃. According to the results, the digestion procedure with the mixture of HNO₃ + H₂O₂ underestimated especially the Cr concentrations in plant material. The maximum concentrations of Cr (1.3 mg kg^–1, wet weight), Ni (358 g kg^–1; ww), V (36 g kg^–1; ww), and Cd (2.4 g kg^–1; ww) in the immediate vicinity of the point sources were 33, 6, 4, and 8 times higher than the background levels, respectively. The dietary intakes of Cd and Pb were assessed and compared to the health criteria recommendations set by the joint Food and Agriculture Organization and World Health Organization Expert Committee on Food Additives (JECFA). The results showed that, depending on the consumption of lingonberries, human exposure based on the mean concentrations for Pb and Cd varied between 0.04% and 0.07% for Pb and between 0.04% and 0.09% for Cd compared to the tolerable total quantities of 25 g kg^–1 for Pb and 7 g kg^–1 for Cd per body weight per week set by JECFA.     

Biological assessment of exposure to antimony and lead in the glass-producing industry

Summary The oxide of trivalent antimony is used in the glass-producing industry as a refining agent and as a glass colouring. The batch contains up to 2% Sb₂O₃, a substance which has shown carcinogenic properties in animal experiments. The internal levels of antimony and lead in blood (SbB and PbB) as well as the excretion with the urine (SbU and PbU) were determined by hydrid and electrothermal atomic absorption (HY-AAS and ET-AAS), respectively. In addition, measurements of airborne Sb₂O₃-concentrations were performed. The 109 volunteers were employed in four different fields: melting area, batch bunker, glass-washing area, and transport/maintenance. Differences between the concentrations of antimony and lead in blood and urine with respect to the fields of activity were evaluated statistically. The highest values of airborne Sb₂O₃ with up to 840 g/m³ (TWA), were detected in the batch bunker. Correspondingly, significantly enhanced SbU-values from 1.5 to 15.7 g/l (median: 5.0 g/l were found in specimens collected from the batch mixers. In the same group, the lead excretion (PbU) with values from 9 to 110 g/l (median: 43 g/l) was also found to be the highest. Due to the fast renal excretion of antimony, the determination of SbU is useful for biological monitoring.     

Isomer-specific analysis and toxic evaluation of polychlorinated biphenyls in striped dolphins affected by an epizootic in the western Mediterranean sea

Isomer-specific concentrations of polychlorinated biphenyls (PCBs) including planar, mono- and di-ortho congeners and concentrations of DDT were determined in striped dolphins affected by a morbillivirus epizootic in the western Mediterranean in 1990. Extremely high concentrations of PCBs ranging from 94 to 670 g/g (wet wt) were detected in the blubber. Similarly, DDT concentrations were high, between 22 and 230 g/g (wet wt). The concentrations of three non-ortho coplanar PCBs were 43 (3,3,4,4-T₄CB), 6.8 (3,3,4,4,5-P₅CB), and 7.8 (3,3,4,4,5,5-H₆CB) ng/g (wet wt), respectively, the highest residue levels reported to date. The estimated 2,3,7,8-TCDD toxic equivalents of non-, mono- and di-ortho PCB congeners in striped dolphins were several times higher than those observed for other marine mammals and humans. Mono-ortho congeners contributed greater 2,3,7,8-TCDD toxic equivalents than non-ortho members. The higher ratio of 3,3,4,4,5,5-H₆CB/3,3,4,4,5-P₅CB (IUPAC 169/126) suggested a strong induction of mixed function oxidase enzymes and highlighted the possibility of using this ratio as an index for risk assessment of PCB contamination in marine mammals. Elevated concentrations of PCBs may have played a role in the immune depression in striped dolphins, ultimately leading to the development of morbillivirus disease.     

Energy potential and hepatic function in rats under acute exposure to carbon disulphide

Summary In adult female rats 8-hr exposure to 400 ppm CS₂ did not produce a change in conventional liver function tests (SGOT, SGPT, and SLDH activities; BSP clearance in the bile). This would seem to imply that the severe inhibition of the hepatic mixed-function oxidases observed in earlier experiments after the same dose of CS₂ is not attributable to generalized cell damage, but should rather be taken to represent a selective lesion. Eight-hr exposures of the experimental animals to graded CS₂ concentrations ranging from 20 to 400 ppm triggered a rapidly reversible substantial depletion of the hepatic glycogen. A concurrent increase of the lactate and inorganic phosphate levels and also of the oxygen consumption was demonstrated, in conjunction with an increased respiratory uptake of oxygen by the exposed animals, a fall in body temperature, and a decrease of the serum potassium and calcium levels. These changes may be interpreted as an extensive defect in the energy supply in the liver cell. The concomitant slight decrease of the liver weight is largely explained by the disappearance of glycogen; a possible reduction of the water content could be excluded. The small increase in total liver protein, which was another finding, is attributable to a nonspecific stimulation of protein synthesis. The observed quantitative changes in the liver substance required balancing of the food ingested: following 8-hr inhalation of 100 or 400 ppm there was a marked reduction in body weight, intake of standard food and water, and fecal excretion, whereas slight increases were observed after 20 ppm over 8 hrs. These alterations are probably due to a disturbance of the diencephalic controlling mechanisms.Presented in part at the 10th Spring Meeting of the Deutsche Pharmakologische Gesellschaft, Mainz, March 16 – 19, 1969.     

Decreased excretion of thioethers in urine of smokers after the use of β-carotene

Summary Epidemiologic studies have demonstrated an inverse relation between vitamin A intake and lung cancer rate. There is strong evidence that the provitamin A, -carotene, plays a more important role in the protective effect than vitamin A itself. The anticarcinogenic properties of -carotene have so far been attributed to its scavenger properties in deactivating or trapping reactive chemical species such as singlet oxygen and certain organic free radicals. Smoking results in increased excretion of detoxification products of electrophilic agents (mercapturic acids) in urine. Since reactive electrophilic intermediates are involved in carcinogenesis, we performed a double-blind, placebo-controlled intervention trial to investigate whether the intake of -carotene by smokers would affect urinary thioether excretion. Before the intervention the -carotene group (n = 62) and the placebo group (n = 61) had similar thioether excretion levels in urine (4.2 vs 4.3mmolSH/molcreatinine). During the intervention (20 mg -carotene daily for 14 weeks) the placebo group showed a 12% increase, whereas the -carotene group showed a 5% decrease (P=0.004). After the intervention the -carotene group had a 15% lower thioether excretion level than the placebo group (4.1 vs 4.7 mmol SH/mol creatinine; P=0.0017). Our study shows that urinary thioether excretion varies considerably over time, and that smokers have a decreased excretion of thioethers in urine after the use of -carotene. This latter observation suggests a role of -carotene in the detoxification of tobacco smoke constituents. Our observations warrant further studies on the involvement of -carotene in the generation and detoxification of electrophilic intermediates.     

Toxicity of iodine,iodide, and iodate to Daphnia magna and rainbow trout (Oncorhynchus mykiss)

The acute toxicity (96-h LC₅₀) of aqueous stable iodine species (I^–, IO ₃ ^– , I₂) to rainbow trout and Daphnia magna were measured at three individual concentrations of hardness, total organic carbon, and chloride. Rainbow trout were most sensitive to I₂ (LC₅₀0.53 mg/L), and much less sensitive to IO ₃ ^– (LC₅₀220 mg/L) or I^– (LC₅₀860 mg/L). Daphnia magna were equally sensitive to I₂ (LC₅₀0.16 mg/L) and I^– (LC₅₀0.17 mg/L), but were less sensitive to IO ₃ ^– (LC₅₀10.3 mg/L). The external and internal radiological dose imparted by equivalent molar quantities of radioactive ¹²⁵I, ¹²⁹I, and ¹³¹I were calculated for both the Daphnia and trout using the LC₅₀ values obtained from a standard water treatment. As expected, the dose from ¹²⁵I and ¹³¹I would exceed the expected lethal dose rate long before a chemically toxic level is reached. In contrast, a molar concentration of ¹²⁹I likely to cause death by chemical toxicity would impart a radiological dose less than that expected to be lethal. Thus, for short-lived aquatic organisms, risks due to chemical toxicity of ¹²⁹I may exceed risks due to its radioactive emissions.     

Untersuchung über die Aufnahme und Bindung von CS2 an körpereigene Stoffe mit neuer Bestimmungsmethode

Zusammenfassung Eine Nachweismethode für CS₂ im Bereich von 3–200 wurde auf der Basis einer Reaktion mit Diäthylaminreagens und photometrischer Bestimmung als Kupfer-Diäthyldithiocarbamat entwickelt.Mit diesem Verfahren wurde das Verhalten von CS₂ gegenüber Bluteiweißkörper und S-haltigen Verwendungen studiert. Pseudoglobulin zeigte nur eine sehr geringe Bindungsfähigkeit. Beim Euglobulin war die Bindungsreaktion deutlich, beim Albumin war sie am stärksten. Cystein erwies sich als besonders reaktionsfähig mit CS₂. Die freie SH-Gruppe scheint Angriffspunkt der Bindung zu sein.Diese Prüfung des Bindungsvermögens wurde bei gleicher Versuchsanordnung mit radioaktivem CS ₂ ³⁵ wiederholt. Aktivitätsmessungen auf Isotopenschwefel ergaben, daß die Reaktion bei den mit CS₂ reagierenden Stoffen durch einen Schwefelaustausch überdeckt wird. Damit wird die Bestimmung des CS₂-Gehaltes im organischen Material nach diesem Verfahren unzuverlässig.Mit 3 Textabbildungen.     

Fumigant contamination during large-scale food sampling for analysis

Incurred fumigants were determined from twenty-two food items before and after routine large-scale preparation of samples to see if these or similar kinds of chemicals were entering the samples during the preparation. This preparation includes making the samples table ready before compositing them for analysis. The following five fumigant residues were determined by gas chromatography (GC): carbon disulfide (CS₂), carbon tetrachloride (CCl₄), chloroform (CHCl₃), methyl chloroform (CH₃CCl₃), and tetrachloroethylene (or perchloroethylene, PCE). The number of residues determined from each sample ranged from none to four. The amounts determined varied significantly between the before and after portions from several samples. Four samples gained at least one new residue during the preparation. Six lost most of the residues determined from the original before portions, and 12 contained essentially the same residues before and after the preparation, although the amounts varied between the two portions. In samples where the variant residues were detected in both portions, five showed a tenfold or greater increase of CHCl₃ or CCl₄ and two showed a ten-fold or lesser decrease of CH₃CCl₃ or PCE in the after portions.     

Measurement of manganese amelioration of cadmium toxicity inChlorella pyrenoidosa using turbidostat culture

Cadmium (Cd) toxicity and amelioration of Cd toxicity by Mn were measured inChlorella pyrenoidosa, using turbidostat culture. The responses were measured in terms of the maximum specific growth rate, _max, of the populations. In turbidostat culture _max is a dependent variable that can be measured continuously. Cd (as CdCl₂· 2.5 H₂O) was added to control populations at a concentration of 1.8 M Cd. Toxicity was expressed after a 5 generation lag and resulted in a _max steady state 62% lower than the initial control after 2 generations. With continued Cd exposure, Mn (as MnCl₂ · 6H₂O) was then added stepwise to a concentration of 10.4 M Mn which caused a rapid, immediate increase in _max followed by linear increase until a steady-state plateau was reached at a _max 90% of control. The ameliorative response spanned 20 culture generations. After addition of Mn (10.4 M), cellular Cd concentration did not change and cellular Mn concentration increased. Increase in mean cell size accompanied Cd exposure and was significantly decreased when supplemented with 10.4 M Mn. Possible mechanisms of the amelioration are discussed.