Demonstration of sperm head shape abnormality and clastogenic potential of cypermethrin.

Adult male Swiss albino mice were administered ip. suspension solution of cypermethrin in 0.15% DMSO at the doses of 30 mg, 60 mg and 90 mg/kg b. wt. daily for 5 days. Another group of animals was injected cyclophosphamide ip. (60 mg/kg b. wt.) in similar manner which served as positive control. Effect of cypermethrin on body and testes weight and sperm head morphology was studied. Clastogenic potential of cypermethrin was studied by using modified Allium test. The cytological changes were studied in the root tip cells of Allium cepa after 3 days treatment with three different concentration of cypermethrin (0.1, 1.0 and 10.0 microg/ml). The results revealed that body weight gain was considerably reduced in higher dose groups, but the testicular weight did not change significantly in any of the cypermethrin treated groups. However, a significant elevation in the number of abnormal shape of sperm head was noticed in higher dose groups as compared to control. It was observed that the abnormality in the shape of sperm head was dose-dependent. The cytological changes in the root tip cells of Allium cepa indicated that cypermethrin is having toxic effects on the root tip cells in the form of stickiness of chromosomes and also affect the mitotic activity. This study suggest that cypermethrin may have the potential to induce adverse effects on sperm head shape morphology of mouse as well as clastogenic effects on root tip cells of Allium cepa.

A review: neural control of mastication in humans as influenced by food texture.

This review summerizes recent approaches to the physiology of the masticatory system in humans that aim to understand how the process is influenced by the material properties of foods. The centerpiece is a group of experiments that show that the rate of breakdown of food in human mastification depends principally on the combination of two mechanical properties of foods: toughness(R) and modulus of elasticity (E). Two mechanical indices are constructed from these properties: the square root of their product, (ER)0.5, is predicted to explain the resistance to an incisal bite, while the square root of their ratio, (R/E)0.5 is predicted to control the rate of fragmentation during a postcanie bite. Evidence for the latter is reviewed, which also appears to modulate the activity of jaw closing muscles and the extent of lateral mandibular movement during mastication. These studies provide a quantified link between the food stimulus and the physiological response of the mastiatory system for which we know of no parallel. Attempts to extend this analysis have been made by psychophysical investigations of food texture. These support some sensitivity to the mechanical index that we have identified, but are not conclusive. Finally, we provide a chart summarizing physiological responses to food texture that could interest dentists, food scientists and also those interested in the analysis of dentition and diet in mammals.