C.R. Krishna Murti

Agrochemicals in the maternal blood, milk, and cord blood: a source of toxicants for prenates and neonates

Abstract The circulating blood, breast milk, and cord blood, collected 24–48 hr after child birth of nursing Indian mothers were examined for the presence of organochlorine insecticides (OCI). Significant levels of BHC and DDT were found in all milk, blood samples, and neonatal blood (cord blood) of mothers. No effect of social status, age, dietetic habits, or area of residence on the susceptibility of subjects examined to accumulate OCI was noticed. Significant correlations of total DDT and BHC levels were observed among maternal blood, neonatal blood, and breast milk. The presence of OCI in the cord blood indicates their passage across the placenta to prenates, whereas contamination of breast milk which is consumed by neonates could shed some light on a far greater daily intake of toxic agrochemicals by neonates.

Placental transfer of pesticides in humans.

Transfer of organochlorine pesticides from mother to fetus has been studied in 100 women. The concentrations of organochlorine pesticides were examined in maternal blood, placenta, and umbilical cord blood of the same mother/child pair. Residue levels of dichlorodiphenyl trichloro ethane (DDT) and its metabolites, isomers of benzene hexachloride (BHC) and aldrin were detected in all the samples analyzed, indicating their transfer from mother to the fetus. A correlation was found to exist between the pesticide concentration and age, dietetic habits and area of residence of pregnant women.

Comparative studies on ecotoxicology of synthetic detergents

To predict the comparative toxicological response of synthetic detergents on aquatic ecosystems, the effects of various concentrations of neutralized alkyl benzene sulfonate were studied. The median tolerance limit at 48 hr, 95% confidence limit, slope function, presumable harmless concentration, and rate of survival of different species of aquatic fauna such as water fleas (Daphnia magna), mosquito larvae (Culex pipiens), slug worms (Tubifex rivulorum), snails (Lymnaea vulgaris), tadpoles (Rana cyanophlyctis), and fish fingerlings (Cirrhina mrigala) were followed at 0, 24, 48, 72, and 96 hr. Any effect on quality of the water was also tested after the addition of various concentrations of detergents. The results showed that water fleas are more susceptible to detergent toxicity than fish fingerlings, tadpoles, slug worms, snails, and mosquito larvae. Behavioral changes were also observed as an index for detergent toxicity. The relative toxicity of the detergents to various species is discussed in relation to selective ecotoxicological response.

Binding of acrylamide with glutathione-S-transferases

Introduct ion GST, a family of cytosolic enzymes, plays an important role in cellular biotransformation and elimination of toxic electrophiles by glutathione conjugation and subsequent excretion as mereapturic acid [1,2]. GST bind a broad range of substrate and non~substrate ligands and subsequently function both as catalytic proteins for cellular biotransformation and as an organic anion or receptor protein [ 3--7 ]. ACR (CH2CHCONH2) is an extensively used monomer in polymer industry and is a potent neurotoxin [8]. Exposure of humans and animals to ACR leads to a typical peripheral neuropathy in nervous system [ 8]. To date very little is known about the biotransforrnation of ACR [9]. Our recent studies have demonstrated that ACR reacts with glutathione both nonenzymically and enzymically. Enzymically both liver and brain GST catalyze the formation of S-conjugates and therefore acrylamide acts as substrate for GST (R. Dixit et al., pets. comm.). In view of the wide range of ligands (both substrate and non~substrate) that bind to GST [3--7], it was of interest to study interaction of ACR with GST. The present report summarises the observations which suggest that the conjugating enzyme may be identical with the protein which binds ACR.

Bilirubin-induced erythrocyte membrane cytotoxicity

The kinetics of bilirubin erythrocyte interaction have been followed by scanning electron microscopy. Bilirubin-induced erythrocyte cytotoxicity embodies the interaction of the bile pigment with the outer half of the erythrocyte plasma membrane bilayer couple. This interaction leads to crenation. This membrane event appears to be primary and precedes hemolysis. The membrane crenation is dependent on the concentration of the bile pigment and is reversed by bovine serum albumin again in a concentration-dependent manner. Phospholipids do not alter bilirubin erythrocyte ineraction. Erythrocytes from jaundiced neonates show crenated surface structure in scanning electron microscopy. The crenation depends upon severity of jaundice in neonates. This suggests similarity between in vivo and in vitro mechanisms of cytotoxicity mediated by the bile pigment. Further, phototherapy reverses the process of membrane crenation. The in vivo photocatabolities isolated from urine of jaundiced neonates are nontoxic to erythrocyte membrane.

Storage of DDT and BHC in Adipose Tissue of Indian Males

Adipose tissue of 50 human subjects (10 to 60 years old) were taken from autopsy cases and analysed by gas-liquid chromatography equipped with an electron capture detector (3H +) for determination of storage levels of BHC (benzene hexa chloride), DDT (dichlorodiphenyl trichloroethane) and its metabolites DDE and DDD in human body fat. The data is reported according to age (length of exposure), dietetic habits and area of residence of the subjects. The results show relatively moderate exposure to DDT and BHC. Levels of residues were slightly higher in non-vegetarian and rural residents than those of their counterpart vegetarian and urban inhabitants. The study suggests that DDT levels in human adipose show a decreasing trend as compared to earlier report of Dale et al. of highest body burden of pesticides being present in indians.

Setaria cervi: Enzymes of Glycolysis and PEP-Succinate Pathway*

SummarySetaria cervi, the filarial parasite inhabiting the Indian water buffalo (Bubalus bubalis Linn.) contained almost all the enzymes involved in glycogen degradation. Significant activities of glycogen phosphorylase, glucokinase, phosphoglucomutase, phosphoglucose isomerase, phosphofructokinase, FDP-aldolase, glyceraldehyde-3-phosphate dehydrogenase, phosphopyruvate hydratase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were detected in cell-free extracts of whole worms.The presence of PEP-carboxykinase, malate dehydrogenase, fumarase and fumarate reductase revealed the functioning of the PEP-succinate pathway in addition to phosphorylating glycolysis and pentose phosphate pathway in the parasite. Excepting fumarate reductase all other enzymes were localized in the particulate-free cytosol fraction, although small amounts of glycogen phosphorylase, aldolase and lactate dehydrogenase were also detected in the mitochondrial fraction.

Lipid peroxidation in tin intoxicated partially hepatectomized rats.

In recent years the toxic effects of tin have been the subjects of numerous studies. Studies from this laboratory have demonstrated that tin alters mitochondrial function, reduces the content of sulfhydryl groups and subsequently inhibits the activity of sulfhydryl containing enzymes. It was suggested that a possible mechanism for the altered physiology of the cells may involve lipid-peroxidation process. It has been reported that glutathione a cofactor for the selenium dependent GSH-peroxidase which reduces the content of lipid peroxides has been implicated in the defence mechanism against lipid peroxidation. The present work was designed, therefore, to investigate the effects of tin-tartrate on normal and regenerating hepatic tissue and to determine the extent of any association with lipid peroxidation and hepatic glutathione content. Regenerating rat liver, a growing model system, was taken into account to assess the health risk due to heavy metals pollution in a growing population.

Effect of synthetic detergents on some of the behavioral patterns of fish fingerlings (Cirrhina mrigala) and its relation to ecotoxicology

With the wide spread use of synthetic detergents for household purpose, it is inevitable that these compounds would find their way into rivers and ponds. The effect of detergents on tissue of different fishes have been studied by Abel (1974) and Bromage et al. (1976). Gills, a primary site of osmoregulation, as well as respiration, may be highly vulnerable to lesions because they are in immediate contact with aquatic toxicants. The most prominent manifestation of the acute toxicological effect of detergents is on the gi~ tissue of the fish. Destruction of the gill epithelium is regarded as a consequence of the reduction of surface tension by the presence of surfactants (Bock 1965). Exposure of fish to elevated level of surfactants cause multiple hepatomas to develop on the gill tissue resulting in diminished oxygen uptake and impairment of electrolyte balance (Schmid and Mann 1961). Schooling patterns of fish have been reviewed by Partridge (1982). Detergent causes impairment of chemoreceptor organs (Bardach et al. 1965) and damage to epidermis and pharyngeal wall (Brown et al. 1968). Eleven species of fish exposed to a mixture of hard alkyl benzene sulphonate based detergent under varying environmental conditions and during different stages of development have shown wide differences in response (Thatcher 1966). Behavioural changes have been used successfully as rapid and sensitive indicators of toxic stress in fish (Sprague et al. 1965; Bengtsson 1974 and Besh et al. 1977).

Evidence for the possible involvement of the Superoxide radicals in the photodegradation of bilirubin

The photodecomposition of bilirubin follows first order kinetics with akB value of 12.5 × 10-3 min-1. In the presence of a model system generating superoxide anions, such as xanthine-xanthine oxidase, thekB value was 103 × 10-3 min-1 This ten-fold enhancement ofkB value by xanthine-xanthine oxidase was abolished when the reaction mixture was supplemented with a superoxide ion scavenger— superoxide dismustase. Further, known singlet oxygen quenchers like Β-carotene and bistidine did not prevent the enhancement of bilirubin oxidation by xanthine-xanthine oxidase, thereby ruling out the obligatory conversion of Superoxide anion to singlet oxygen. It is concluded that radical oxygen mediated bilirubin degradation might be a natural catabolic route for the bile pigment degradation during oxygen stress.