Effects of metals on chromosomes of higher organisms

An analysis of the available data on the clastogenic effects of metals and their compounds on higher organisms indicates some general trends. Following chronic exposure to subtoxic doses, a decrease in mitotic frequency and an increase in the number of chromosomal abnormalities are observed. These effects are usually directly proportional to the dose applied and the duration of treatment within the threshold limits. Recovery after acute treatment is inversely related to the dosage. The ultimate expression of the effects depends on certain factors, including the mode and vehicle of administration; the form administered; the test system used; the rate of detoxification, distribution, and retention in the different tissues; and interaction with foreign and endogenous substances as well as the mode of action with the biological macromolecules. In mammals, the clastogenic activity of the metals within each vertical group of the periodic table is directly proportional to the increase in atomic weight, electropositivity, and solubility of the metallic cations in water and lipids, except for Li and Ba. This pattern of inherent cytotoxicity increases with successive periods in the horizontal level. It is enhanced by the formation of covalent and coordinate covalent complexes by heavy metals with the biological macromolecules. In plants, the solubility of the metals in water is of much greater importance. The degree of dissociation of metallic salts and the rate of absorption affect significantly the frequency of chromosomal aberrations. In assessing the effects of environmental metal pollution, the presence of other metals and toxic chemicals and the level of nutrition should be taken into account, since in nature, metals occur in combination and these factors modify the cytotoxic effects to a significant extent.     

Alterations in free radical scavenger system profile of type I diabetic rat brain

The activities of the enzymes related to glutathione synthesis, degradation, and functions as well as reactive oxygen scavenging enzymes were analyzed in different brain regions, such as cerebral hemisphere, cerebellum, brainstem, thalamus, and hypothalamus after 1 and 3 mo of streptozotocin-induced diabetes in rats. Parallel studies were also made in age-matched control rats and insulin-treated diabetic rats. The content of glutathione (GSH) and its synthesizing enzyme γ-glutamylcystein synthetase and also superoxide dismutase (SOD) and catalase activities (reactive oxygen scavenging enzymes) were significantly decreased from almost all the brain regions studied. However, glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), γ-glutamyl transpeptidase (γ-GTP), and glutamine synthetase (GS) activities were increased in the diabetic rat brain. Insulin treatment to the diabetic rats resulted in partial to full recovery in these enzymes activities. The present results emphasize the potentially serious alterations of brain free radical scavenger system in uncontrolled Type I diabetes.     

Clinical considerations in the use of missing tissue compensators for head and neck cases

The irregular shape or contour of the patient’s surface in the treatment field can alter the dose distribution resulting in non-uniformity of dose in the treatment volume. Missing tissue compensators have been most commonly used to improve this non-uniformity, especially in head & neck, breast, lung and supraclavicular regions. Two or three dimensional compensators have been typically designed to make the dose uniform at a specific depth. This compensation shifts the dose distribution within the treatment volume so that some structures may be under or over compensated. This study will examine how various sites in head and neck cases are affected by compensators. We have also analyzed the uncertainty in compensated dose due to the daily variations in patient repositioning. Computer isodose plans using Cobalt-60 gamma rays and 6 and 18 MV x-rays were generated using coronal contours. Results show that the dose uniformity is improved for the treatment sites, especially for the thinner sites, like the larynx and the anterior cervical neck nodes. Finally, patient movement or positioning errors of ±1.0 cm will cause a change in dose distribution.     

Synthesis and Antitumour Activity of New Derivatives of Flavone-8-acetic Acid (FAA). Part 1: 6-Methyl Derivatives

A range of 17 derivatives of flavone-8-acetic acid (FAA) with a 6-methyl substituent have been prepared and their anti-tumour activity evaluated in vitro against a panel of human and murine tumour cell lines and in vivo against MAC 15A. While many of the compounds show activity comparable to FAA in vitro, this essentially disappears in vivo, possibly due to degradation before the compounds can reach the tumour site.     

Efficacy of the steroidal fraction of fenugreek seed extract on fertility of male albino rats

T. foenum-graecum seed extract (100 mg/day/rat) was fed orally to male albino rats for 60 days. The sperm count and motility of cauda spermatozoa declined significantly leading to negative fertility tests. The organ weights as well as androgen dependent parameters (protein, sialic acid and fructose) were lower, revealing the reduction in circulating androgen. Cholesterol is a precursor of androgen. The increase in testicular and serum cholesterol may be co-related with its nonutilization by the system, leading to a fall in circulating androgen and hence the altered histoarchitecture observed. Therefore T. foenum-graecum extract exerts both antifertility and antiandrogenic activities.     

Aspiration vs nonaspiration technique of cytodiagnosis--a critical evaluation in 160 cases

The two sampling techniques were studied in 160 randomly selected cases of superficial swellings in various sites of the body. They were sampled by fine needle aspiration (FNA) and by non-aspiration (NA) (a needle without application of aspiration pressure). Cell samples were cytologically assessed and critically evaluated using five objective parameters. Contamination with blood was more in lymphnode, thyroid and liver lesions in aspiration smears than NA smears and values were statistically significant. Similarly when compared for the degree of cellular trauma and cellular degeneration statistically significant better results were obtained by nonaspiration technique for lymphnode lesions. Regarding amount of cellular material obtained by FNA, statistical significant better results were found for breast lesions only. Statistically significant better maintenance of architecture was observed only for thyroid lesions by NA technique. Better average scores were observed by NA technique for lymphnode and thyroid only. Categorizing all the smears obtained by FNA & NA on the basis of their scores according to predetermined criteria, greater number of diagnostically adequate specimens were obtained by FNA than by NA but the number of diagnostically superior specimens obtained by NA technique was found to be more than that by FNA. The difference was found to be statistically significant. However the number of inadequate smears was also more by NA technique than by FNA technique.     

AgNORs in endometrial lesions

Silver nucleolar organizer region (AgNOR) staining was employed in one hundred specimens of endometrium. These included fifteen normal controls (Proliferative + Secretory endometrium) and eighty five lesions. Endometrial lesions comprised of endometritis (15), endometrial hyperplasia (25) and endometrial carcinoma (45). Three micron thick sections of paraffin embedded tissue were subjected to AgNOR staining as described by Crocker and Smith with a little modification of 0.01% safranin counterstain--The mean AgNOR scores were found to increase steadily from normal to endometritis to endometrial hyperplasia and carcinoma--The observations revealed statistically significant differences in values between atypical hyperplasia and carcinoma also. AgNOR staining and scoring is simple, inexpensive and a useful adjunct to routine histopathology to evaluate endometrial lesions especially to differentiate borderline lesions. Though scores cannot be standardized and fixed for a particular lesion as there are intralaboratory variations.     

The goldfish optic tectum: a Golgi study.

The detailed morphology of neurons in the optic tectum of the common goldfish, Carassius auratus, was reinvestigated using rapid Golgi and Golgi-Cox methods. Neurons were classified initially on the basis of the orientation of the primary dendritic processes within the tectum: vertical, horizontal and non-oriented. These 3 groups were subdivided according to the shape of the soma and the axonal and dendritic configurations.The cell types observed in the present study were compared with those reported in earlier analyses of the goldfish optic tectum. Numerous differences, primarily of soma location and axonal origin and pathway for each cell type, were found. The structure of the goldfish optic tectum appears to be quite similar to the tectum of other teleosts.