False-negative amniotic fluid acetylcholinesterase in a case of meningo-encephalocele

We describe a patient with a significantly elevated serum alphafetoprotein (AFP) concentration at 17 weeks of gestation, who showed only a marginally increased amniotic fluid AFP and lacked the second rapidly migrating band of acetylcholinesterase electrophoresis. Ultrasound examination revealed an encephalocele and ventriculomegaly. Autopsy showed that the encephalocele was not covered by skin.     

Toxicological attributes of plant chemicals and their biochemical impacts on cholinesterase and protein levels in relation with conventional insecticides against mosquito larvae of Karachi city

In order to control mosquito, different chemicals were applied against the larvae of Culex fatigans (Diptera Culicidae). The tested chemicals were Lambda cyhalothrin, chlorpyrifos, Azadirachta indica (Spindales meliaceae) neem extract, and Sueda monoica extract. All chemicals were found to have significant efficacy against Culex fatigans mosquito larvae. In terms of efficacy, the biochemical effects after treatment with such chemicals were found to vary. Total protein levels and acetylcholinesterase (AChE) activity were the parameters examined. Chlorpyrifos, Lambda cyhalothrin, and neem elevated AChE activity levels whereas the plant extract S. monoica decreased enzymic activity. Total protein levels were decreased by Lambda cyhalothrin and chlorpyrifos whereas protein was increased by neem extract and S. monoica.     

Effects of the organophosphate insecticide azinphos-methyl on the reproduction and cholinesterase activity of Biomphalaria glabrata

Azinphos-methyl is an organophosphate insecticide used for pest control on a number of food crops in many parts of the world. The snail Biomphalaria glabrata is a freshwater gastropod widely distributed in South America, Central America and Africa. The aim of the present work was to investigate whether azinphos-methyl causes alterations in the reproduction of B. glabrata. To this end, gastropod pigmented specimens were exposed to various concentrations of the insecticide (0.021, 0.5, 2.5, and 5 mg L⁻¹) for either 2 or 14 d. Along 14 d, several reproduction parameters and cholinesterase (ChE) activity were evaluated. In each group, the number of egg masses, the number of eggs per mass, the number of hatchings, the time to hatching, and the survival of the offspring after one month of treatment was evaluated. The results showed that, depending on the concentration and time of exposure, azinphos-methyl induced alterations in the reproduction of B. glabrata. These alterations were mainly represented by a decrease in the number of egg masses, and, in some cases, by a lower number or even the total absence of hatchings. Thus, the gastropods exposed to 2.5 and 5 mg L⁻¹ of azinphos-methyl for 14 d showed ChE inhibitions higher than 35% along time and completely lost their ability to reproduce. On the other hand, exposure to high acute concentrations or exposure to low concentrations for 14 d resulted in ChE inhibition equal to or lower than 35% between 7 and 14 d of treatment and similar alterations in reproduction. These were represented by a decrease in the number of egg masses. At low pestice levels, the number of egg masses and the number of offspring resulted to be more sensitive biomarkers than ChE inhibition. It is concluded that the insecticide azinphos-methyl can cause a decline in the reproductive performance of B. glabrata.     

Biochemical effects of some organo‐phosphorus insecticides on new targets in white rats

Abstract

The three S‐n‐propyl phosphates and phosphothioates: RH 218, profenofos and prothiophos were compared with fenitrothion in their potential as inhibitors of rat liver and brain AChE. Fenitrothion was more potent as an inhibitor than the three S‐n‐propyl derivatives. Incubation of hepatic protein enhanced ChE inhibition in brain in the case of fenitrothion, while it reduced the inhibitory effect of the S‐n‐propyl derivatives. On the other hand, the four organophosphorus esters caused hypoglycemia in both male and female rats and also reduced their blood urea with different degrees.     

Hematological and biochemical alterations in sprayers occupationally exposed to mixture of pesticides at a mango plantation in Lucknow,India

The aim of this study was to examine the hematological and cholinesterase (ChE) activity levels of pesticide sprayers employed in mango plantations at Lucknow. Fifty-two sprayers from mango plantations who regularly spray mixtures of pesticides including organochlorines (OC), organophosphates (OP), and carbamates were included as exposed group. Twenty residents living close to mango plantations, but not involved in pesticide spraying were taken as controls. Pesticide residues for OC were analyzed in blood by gas chromatography with electron capture detector. There was a significant decrease in acetylcholinesterase and butyrylcholinesterase activities in pesticide sprayers (n?=?52) relative to the control group (n?=?20). A significant difference in the frequency distribution of hematological variations in red blood cell, white blood cell, monocytes, neutrophils, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and platelet count was observed. Residues of OC pesticides including α-hexachlorocyclohexane (HCH) and total HCH were found to be significantly higher in the blood of sprayers compared to controls. Hematological variations were quantitatively more frequent among the sprayers with 5 years of pesticide exposure compared to the controls and to subjects with less than 5 years of exposure group. Hematological abnormalities in sprayers were correlated with pesticide exposure as evidenced by lower ChE activity as well as the presence of OC pesticides in blood. The poorly controlled use of pesticides in the plantation appeared to have produced sub-clinical intoxication in the sprayers and indicated the need for training and implementation of proper, safer hygiene practices.     

Sublethal concentrations of azinphos-methyl induce biochemical and morphological alterations in Rhinella arenarum embryos

Considering that amphibians are good sentinels of environmental conditions, Rhinella arenarum embryos were used to investigate the effects of sublethal concentrations of the organophosphorus insecticide azinphos-methyl, focusing on its anticholinesterasic or pro-oxidant actions and its possible connection with the appearance of morphological alterations. Early amphibian embryos exposed to azinphos-methyl displayed a protective response through glutathione S-transferase induction, along with superoxide dismutase inhibition. At intermediate embryonic stages, embryos exposed to azinphos-methyl displayed superoxide dismutase inhibition and morphological alterations, although cholinesterase activity was not altered, suggesting that molecular targets other than cholinesterase were involved in the development of morphological alterations. At the end of embryonic development, decreases in reduced glutathione and cholinesterase inhibition were observed, along with a significant increase in the number of malformed embryos. The connection between biochemical alterations and the appearance of malformations was not evident in R. arenarum embryos. However, increased glutathione S-transferase and decreased superoxide dismutase activities could be considered as early markers of exposure to azinphos-methyl. The results obtained demonstrate that sublethal concentrations of azinphos-methyl are a serious threat to toad embryos in their natural habitats because biochemical and morphological alterations could impair their ability to deal with environmental stresses.     

European starling nestling response to chlorpyrifos exposure in a corn agroecosystem

European starling (Sturnus vulgaris) nestlings were used as a surrogate to study the effect of chlorpyrifos application to a corn agroecosystem on songbird reproduction. Chlorpyrifos was applied in a T‐band at 1.3 kg AI/ha, and residues were measured in soil, earthworms, ground‐dwelling insects, and diet items collected from the crop of starling nestlings. Chlorpyrifos levels in soil peaked at 34.2 μg/g, 4 days post‐application, and dissipated to trace levels by 64 days post‐application. Concentrations of chlorpyrifos in earthworms and ground‐dwelling insects reached 0.9 and 0.7 ug/g, respectively. Starling nestling diet items included invertebrates from eight orders with chlorpyrifos concentrations ranging from trace levels to 10.6 μg/g in earthworms. Nestling brain and plasma cholinesterase (ChE) activity and body mass measurements were taken at 3, 8, and 13 days post‐hatch (DPH). Adult starling fecundity was also measured. Body mass differences between treatment and reference site nestlings at 3 and 13 DPH were not significant at α = 0.05. However, 8 DPH nestlings from the Treatment Site had a transient reduction in weight (p = 0.03) when compared with 8 DPH reference nestlings. There were no significant differences in brain or plasma ChE activities of 3, 8, or 13 DPH nestlings. Further, multiple measures of fecundity (i.e., clutch size, hatching percentage, and fledging percentage) indicated that chlorpyrifos application did not affect starling nestling survival to fledging, as the values from the Treatment and Reference Site were nearly identical. This screening‐level study suggests that although one age group of starling nestlings from the Treatment Site weighed less than their Reference Site counterparts, a single T‐band application of chlorpyrifos did not impair starling nesting success.     

A prospective study of amniotic fluid cholinesterases: Comparison of quantitative and qualitative methods for the detection of open neural tube defects

The value of quantitative and qualitative methods of cholinesterase (ChE) analysis in the detection of open neural tube defect (NTD) has been assessed in a prospective survey of 1495 mid-trimester amniotic fluids. Using a quantitative method the mean ChE values were much lower in fluids from pregnancies of normal outcome but it was not possible to discriminate these fluids completely from those associated with NTD pregnancies. particularly when the specimens were contaminated with blood. Similarly, measurement of acetylcholinesterase (AChE) activity alone by three different methods also failed to eliminate the overlap between the two groups. In contrast, polyacrylamide gel electrophoresis revealed only a single band of ChE activity in 1408 out of 1410 fluids from pregnancies with a normal outcome whilst amniotic fluids from all 60 cases of open NTD. 6 out of 7 cases of exomphalos and 3 out of 4 cases of intra-uterine death gave the characteristic second faster-running AChE band. A qualitative gel method which requires the same amount of ChE activity to be loaded from each amniotic fluid is an effective method for pre-natal diagnosis of NTDs.     

Chronotoxicological studies on dichlorphos in mice and humans

Chronotoxicological studies were performed with dichlorphos (DDVP) and its timing toxic effects on mice and humans. The circadian rhythms were revealed in the blood cholinesterase (ChE) activity in intact mice and normal persons, as well as in mice mortality treated at different daily times. The inverse relationship of the two rhythm suggested that the risk of exposure to DDVP might be much higher at evening hours than in other clocks of the day, and the disappearance of the ChE rhythms in DDVP-treated mice and DDVP-exposed workers implicated a disturbing effect of DDVP on the maintenance and regulation of the rhythmic mechanisms.     

The human serum paraoxonase—Polymorphism and specificity

Human serum contains EDTA‐sensitive (Ca⁺⁺‐dependent) and EDTA‐stable (albumin) paraoxonases which hydrolyse paraoxon, 0,0‐diethyl,0–4‐nitrophenyl phosphate.

In Caucasians the EDTA‐sensitive enzyme shows a genetically determined polymorphism which is governed by two alleles. In typical Mongoloid or Negro populations this polymorphism is expressed to a lesser degree, and in a few samples (e.g. Aborigines) it cannot be observed at all. The distribution of the activity of the EDTA‐stable (albumin) paraoxonase is unimodal.

Many authors supposed that paraoxonase is an arylesterase (EC 3.1.1.2) which means that it is also able to hydrolyse phenylacetate or β‐naphthylacetate. New investigations have shown that the human serum fractions splitting paraoxon can be separated from those hydrolysing phenylacetate and related substrates.

The polymorphism of the EDTA‐sensitive human serum paraoxonase can be applied to investigations concerning specificity. From this it becomes evident that this enzyme is rather specific. Already slight changes of the paraoxon molecule lead to a decrease of activity. On the other hand the enzyme seems to hydrolyse also phosphonic acid esters and 4‐nitrophenylacetate in the same way like paraoxon (polymorphism).

There is a linkage relationship of paraoxonase with cystic fibrosis and DNA markers. According to these results the (EDTA‐sensitive) paraoxonase locus is on the human chromosome 7.

A high serum paraoxonase level actually protects serum cholinesterase (EC 3.1.1.8) and has to be considered in biological monitoring of workers exposed to parathion.