A comparative study of in vitro chitin synthase activity in mucoraceous hosts of a mycoparasite

A comparative study of in vitro chitin synthase activity in mucoraceous hosts of a mycoparasite: Chitin synthase, the enzyme responsible for the synthesis of chitin in fungal cell wall was extracted from young hyphae of Choanephora cucurbitarum and Phascolomyces articulosus, susceptible and resistant hosts, respectively, to the mycoparasite, Piptocephalis virginiana. Crude enzyme was identified and characterized by measuring the incorporation of the substrate [14C]-UDP-N-acetylglucosamine, into chitin. Most activity occurred in mixed membrane fraction. Inhibition of activity with Polyoxin D and activation with proteases, N-acetyl-glucosamine and magnesium and other ions was observed. Properties of the crude enzyme preparation such as cofactor requirement, Vmax , apparent Km value for UDP-GlcNAc, inhibition by Polyoxin D, response to pH and to temperature, and stability at 4°C were determined. Enzyme activity from both fungi displayed basically the same features as the corresponding enzymes reported from other mucoraceous fungi. However, the two preparations from P. articulosus and C. cucurbitarum differed from each other in their expressed activity (i.e., the preparations from ~ articulosus exhibited higher latency and higher specific chitin synthase activity than the corresponding preparations from ~ cucurbitarum). Trypsin was effective in activation only over a narrow concentration range. Acid protease was the most effec.tive activator. En.dogenous protease estimation indicated higher protease activity in C. cucurbitarum than in P. articulosus. The suggestion is made that regulation of chitin synthase activities may be related to host resistance in the mycoparasitic system

Characterization of a New Bioactive Calcium Silicate Cement: An Invitro study

INTRODUCTION: Bioactivity and biomimetics are gaining popularity in dentistry in general, and in Conservative Dentistry and Endodontics in particular. These materials stimulate native tissues to repair or regenerate the appropriate tissue where disease and inflammation has caused an imbalance or destruction. Caries, resorption, fracture and other idiopathic diseases cause destruction of dental tissues like dentine, cementum, periodontal ligament and periapical bone. Selecting an ideal bioactive cement for such treatments is paramount in ensuring success. AIM OF THE STUDY: To formulate and characterize an indigenous affordable Experimental Calcium Silicate cement to overcome the disadvantages of MTA and other contemporary Calcium Silicate cements. MATERIALS AND METHODS: In this study an indigenous new experimental Calcium S ilicate cement was formulated to overcome few disadvantages of MTA, however to retain its remineralization potential comparing it with MTA. Characterization of the cements was done using XRD, setting time was measured with Vicat needle apparatus, compressive strength and push out bond strength were assessed in universal testing machine, color stability was tested using a spectrophotometer and bioactivity was studied using SEM and EDAX. RESULTS: Characterization of cements revealed their constituent elements. Though setting time and push out bond strength of the new cement were unfavorable, it showed a satisfactory compressive strength and good color stability. In fact the new cement showed improvement in its color after storage in distilled water and NaOCl in contrast to MTA. There was formation of a bone like carbonate apatite at 24 hours and pure HA at 3 months when the experimental cement was immersed in PBS. CONCLUSION: With suitable modifications to accelerate the setting reaction and increase push-out bond strength, the new experimental Calcium Silicate cement can prove to be a viable alternative to MTA at an affordable cost

Effect of amino acid composition of cereal-based diets on growth of preschool children

The efficacy of two diets, one based on wheat and the other on rice, on the growth (height) of preschool children has been tested in trials lasting 6 months. Both diets provided 2 g vegetable protein and 100 kcal/kg body wt. The increase in height of the children fed the rice-based diet was 0.67 cm/month and that of the children on the wheat-based diet, 0.43 cm/month. The children maintained positive nitrogen balance on both diets. Amino acid analyses of the cooked foods showed the wheat-based diet to be limiting in lysine, methionine, threonine, and isoleucine and the rice-based diet in methionine. However, the rate of growth of the children fed the rice-based diet suggests that methionine was not a limiting factor; the recommended intake of methionine (FAO/WHO) is likely to be higher than the requirements of preschool children