A further contribution to the modelling of multi-waveform generators

A method has been presented in recent papers for deriving precisely stabilized waveform generators by relating them to second-order conservative oscillators. The present paper suggests a method for considerably generalizing the previous class ofgenerator models. This should enable the development of a larger variety of waveform generators with ease and flexibility. The new method is analyzed and is shown to possess implications to theoretical biology and other fields.     

The relation between the category of the ‘need’ and the category of the ‘demand’ for information

This paper examines the terminological confusion underlying the study of information use, and reviews the major studies in the field. The conclusion is that confusion in research methods is inextricably linked to a lack of clarity in terminology. Attention is drawn to the significance of different social and cultural contexts in shaping ‘information needs’, and a research scheme is evolved for the study of users of ‘professional information’ in Poland.     

Effect of methyl mercury induced free radical stress on nucleic acids and protein: Implications on cognitive and motor functions

Mercury pollution and acute neurotoxicity of mercury is well known. The recent reports suggest the adverse effect of low dose mercury, though the available literature is still silent on its mechanism. This study was therefore undertaken to probe the effect of low dose methyl mercury induced heavy metal toxicity on free radical stress and its impact on behaviour of male albino rats. Male albino rats were exposed to 1 mg/kg body wt of methylmercury chloride for seven days, on day 8 they were tested for motor and memory functions. They were sacrificed later for biochemical estimations for rate of lipid peroxidation, nucleic acids, proteins in cerebrum, cerebellum and brain stem. There was an increase in the rate of lipid peroxidation showing methyl mercury induced free radical stress. The motor and memory functions demonstrated a clear decline, besides there was a lowering in the levels of nucleic acids and proteins as compared to controls. The results are important in view of recent reports that methyl mercury induced free radical stress results in early ageing and may serve as an initiating factor more specifically for neurodegenerative disorders like Alzeihemer's disease and dementias. The current findings support the notion that incorporating dietary antioxidants like curcumin, ascorbic acid and α-tocopherol in routine diet from early age may help combat the risk of developing such disorders in ensuing years.     

Serum gamma glutamyl transferase (γ-GT) activity in alcoholics with liver abscess and chronic alcoholics

Gamma Glutamyl Transferase (γ-GT) is a microsomal enzyme. Its activity in serum is assayed in alcoholics with liver abscess and alcoholics without liver abscess after screening by ultrasonography. The enzyme activity in serum is increased by 334% in the patients with liver abscess compared to normal control subjects (p<0.0001), and 172% when compared to patients with chronic alcoholism without liver abscess (p<0.0001). The enzyme activity was increased by 59.3% in the serum of patients without liver abscess compared to the normal control subjects (p<0.001). Measurement of γ-GT in serum appears to be a sensitive index in the diagnosis of alcoholics with liver abscess.     

Serum and urinary zinc in zinc miners and zinc smelters

Serum (200.6±64.8 mg/dl) and urinary zinc (1186.0±265.5 mg/l.) of zinc miners at Zawar were significantly higher as compared to zinc smelter workers (Serum 89.7±9.9. mg/dl; Urine 590.0±32.1 mg/l.). Debari and Udaipur residents (Serum 104.0±18.6 mg/dl; Urine 735.0±180.2 mg/l.). This was most likely attributable to higher dietary zinc intake by zinc miners due to higher zinc content of foodstuffs grown in Zawar areas as compared to Debari and Udaipur.     

Detection of enzymes dehydrogenases and proteases inBrugia malayi filarial parasites

Lymphatic filariasis caused mainly by infection fromW. bancrofti andB. malayi remains a major cause of clinical morbidity in tropical and subtropical countries. Analysis ofB. malayi mf, infective larval and adult worm lysates for the activity of enzymes led to the demonstration of activities of three key enzymes of carbohydrate metabolism viz., Malate dehydrogenase (MDH), Malic enzyme (ME) and Glucose-6-phosphate dehydrogenase (G6PDH) in all the three stages of the parasite. The specific activity of all the three dehydrogenases was significantly high in mf lysate compared to their activity in lysates of the other two stages (P<0.001). Analysis by native polyacrylamide gel to their activity inlysates of the other two stages (P<0.001). Analysis by native polyacrylamide gel electrophoresis (PAGE) using 7.5% non-gradient gel showed the presence of two isoforms of each of the three enzymes (MDH, ME & G6PDH) in mf lysate, while only one form of each enzyme was present in L₃ larval and adult worm lysates. Further proteolytic enzyme activity was demonstrated both in microfilarial and infective larval lysates ofB. malayi. While both mf and L₃ larval lysates showed optimal protease activity at alkaline pH of 9.0, the mf lysate showed increased activity also at pH 3.0. The infective larval lysate was markedly inhibited by Tosylamide-L-Phenylalanine chloromethyl ketone (TPCK), a thiol protease inhibitor, while the protease activity in mf lysate was significantly inhibited by both TPCK and a serine protease inhibitor Phenyl Methyl Sulphonyl Flouride (PMSF). In sodium do-decyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), using gelatin copolymerized gel, the microfilarial lysate showed 3 protease molecules of 40 kDa, 180 kDa and 200 kDa and the L₃ larval lysate had 6 protease molecules of 18, 25, 37, 49, 70 and 200 kDa size.     

Diagnostic and prognostic value of the urinary excretion of beta-aminoisobutyric acid in patients with urinary bladder cancer

Urinary excretion of beta-aminoisobutyric acid (BAIB), was determined in 28 active and 12 inactive bladder cancer patients. Mean excretion of BAIB was higher in active cancer patients-187.8 mg/24 hours whereas it was 120.4 mg/24 hours in inactive cancer patients. The increased BAIB excretion in both disease groups was independent of tumour stage. BAIB appears to be a useful diagnositic aid in the assessment of bladder cancer patients.     

Lipid peroxidation and glutathione peroxidase in ischemic heart disease

With the growing interest in the concept of free radicals in the pathogenesis of myocardial ischemia, it was thought worthwhile to study the changes in lipid peroxides and antioxidant enzyme glutathione peroxidase (GPx) in ischemic heart disease (IHD). The study was carried out on 76 patients of IHD-38 of acute myocardial infarction (AMI) and 38 of stable ischemic heart disease (SIDH). They were age and sex matched with 38 normal healthy controls. A significant increase (p<0.001) in lipid peroxides as malondialdehyde (MDA) (5.9±0.7 mmol/L) and a decrease in GPx (24.6±2.2 U/gmHb) was found in patients of AMI when compared with controls. There was no significant difference in these values in SIHD. Thus this study confirms the earlier findings that MDA and GPx are useful parameters in IHD and their magnitude is dependent on severity and/or duration of ischemia. We suggest that these tests would be of use in smaller institutions with limited facilities.