This study investigates the effects of continuous exposure to a widely used organophosphate pesticide, chlorpyrifos, on survival, growth, development, and activity of larvae of the Asian common toad, Duttaphrynus melanostictus Schneider 1799. Larvae were continuously exposed to six different concentrations (1-1,500 μg l(-1)) of commercial-grade chlorpyrifos for 14 days and monitored for 1 additional week. Chlorpyrifos at ≥1,000 μg l(-1) caused significantly high and dose-dependent mortality, and the weekly LC50(7 day-21 day) values ranged from 3,003 to 462 μg l(-1). Larvae surviving exposure to ≥500 μg l(-1) chlorpyrifos showed significant growth impairment, delays in metamorphosis, and decreased swimming activity. Tail abnormalities were the most common morphologic deformity at concentrations of 1,000 and 1,500 μg l(-1) chlorpyrifos. The findings of the present study highlight the need to recognize the potential risk that agrochemicals pose to amphibians inhabiting agricultural landscapes in Sri Lanka and other Asian countries.
This paper reports the histopathological responses of the gill, liver and tail muscle tissues in tadpoles of the Asian Common Toad Duttaphrynus melanostictus (Schneider, 1799) exposed to chlorpyrifos a common organophosphorus pesticide. Tadpoles of Gosner stages 24-26 were continuously exposed to low, mid and high (500, 1000 and 1500 µgl -1 ) concentrations of chlorpyrifos for two weeks. Histological alterations in the tissues of the surviving larvae were microscopically examined both at the end of the exposure period and after a week following the final exposure. Several histological alterations were noted in the gills, liver and tail muscles of the larvae exposed to 1500 µgl -1 of chlorpyrifos. The gills of exposed larvae showed architectural distortion resulting from reduced primary and secondary gill lamellae and blood vessels, and alterations in the gill epithelium. In the liver sinusoidal congestion and dilation, cytoplasmic vacuolation and changes in hepatocytes such as hyperchromatic nuclei and nuclear fragmentation were observed. The tail muscle tissue suffered from severe atrophy and myotomal disintegration. Although histological alterations in the gill and liver tissues were noted only at the high concentration, changes in the muscle tissue i.e. muscle degeneration and atrophy, were apparent at both low and mid concentrations. The degree of damage in surviving larvae in a week following the final exposure was lower than that observed during the exposure, probably indicating recovery or resistance. The findings of the present study emphasize the need to investigate possible sublethal damage induced by pesticides in amphibians inhabiting agricultural habitats.
Chronic kidney disease (CKD) of unknown etiology is recognized as a major public health challenge and a leading cause of morbidity and mortality in the dry zone in Sri Lanka. CKD is asymptomatic and are diagnosed only in late stages. Evidence points to strong correlation between progression of CKD and kidney fibrosis. Several biochemical markers of renal fibrosis have been associated with progression of CKD. However, no marker is able to predict CKD consistently and accurately before being detected with traditional clinical tests (serum creatinine, and cystatin C, urine albumin or protein, and ultrasound scanning). In this paper, we hypothesize that fibrosis in the kidney, and therefore the severity of the disease, is reflected in the frequency spectrum of the scattered ultrasound from the kidney. We present a design of a simple ultrasound system, and a set of clinical and laboratory studies to identify spectral characteristics of the scattered ultrasound wave from the kidney that correlates with CKD. We believe that spectral parameters identified in these studies can be used to detect and stratify CKD at an earlier stage than what is possible with current markers of CKD.
Frequency dependence of the tissue backscatters provides useful information about the tissue structure. Further, it has been found that structure of tissue changes due to different diseases and these alterations cause observable changes in acoustic scattering properties. Several parameters have been developed to identify these alterations and tissue identification. This study has introduced a new tissue characterization parameter, which is Full width at half maximum (FWHM) of the fitted Gaussian curve of the Fast furrier transformed back scattered signal and it has been used to identify two different tissue samples; bovine liver and chicken liver. The experiment was carried out for nine bovines and nine chicken livers and FWHM of the chicken liver 3.72±0.16 was greater than that of bovine liver 3.28±0.16 (p=2.91E-05). Hence, it can be concluded that the bovine liver and the chicken liver can be differentiate using the FWHM parameter.
Chronic kidney disease (CKD) of unknown etiology is recognized as a major public health challenge and a leading cause of morbidity and mortality in the dry zone in Sri Lanka. CKD is asymptomatic and are diagnosed only in late stages. Evidence points to strong correlation between progression of CKD and kidney fibrosis. Several biochemical markers of renal fibrosis have been associated with progression of CKD. However, no marker is able to predict CKD consistently and accurately before being detected with traditional clinical tests (serum creatinine, and cystatin C, urine albumin or protein, and ultrasound scanning). In this paper, we hypothesize that fibrosis in the kidney, and therefore the severity of the disease, is reflected in the frequency spectrum of the scattered ultrasound from the kidney. We present a design of a simple ultrasound system, and a set of clinical and laboratory studies to identify spectral characteristics of the scattered ultrasound wave from the kidney that correlates with CKD. We believe that spectral parameters identified in these studies can be used to detect and stratify CKD at an earlier stage than what is possible with current markers of CKD.
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