Engineering aspects of immobilized lipases on esterification: A special emphasis of crowding, confinement and diffusion effects.

Cross-linked enzyme crystal (CLEC) and sol-gel entrapped pseudomonas sp. lipase were investigated for the esterification of lauric acid with ethanol by considering the effects of reaction conditions on reaction rate. The activation energy for the reaction was estimated to be 1097.58 J/mol and 181.75 J/mol for sol-gel and CLEC entrapped lipase respectively. CLEC lipase exhibited a marginal internal diffusion effect on reaction rate over sol-gel lipases and found to be interesting. The overall reaction mechanism was found to conform to the Ping Pong Bi Bi mechanism. The higher efficiency of sol-gel lipases over CLEC lipases in esterification reaction is mainly due to the combined effects of crowding, confinement and diffusional limitations.

An unusual foreign body in the nasopharynx.

Coins, playing toys etc. are the commonest foreign bodies of food and air passages in children, but such an unusual and large size foreign body in nasopharynx is not very common. Due to structure of the bangle there was no alarming symptoms.

Adsorptive separation of beta-lactam antibiotics: technological perspectives.

An overview on adsorptive separation of cephalosporin antibiotics has been presented. The fundamental aspects on adsorption mechanism, kinetic and column dynamics have been exhaustedly discussed. The importance of molecular modelling studies on deducing implications for design of adsorbents has been highlighted. Finally, some aspects of process design and scale-up of adsorption column have been addressed and research needs of pragmatic importance have been identified.

Perspectives in liquid membrane extraction of cephalosporin antibiotics.

In this paper an overview of the developments in liquid membrane extraction of cephalosporin antibiotics has been presented. The principle of reactive extraction via the so-called liquid-liquid ion exchange extraction mechanism can be exploited to develop liquid membrane processes for extraction of cephalosporin antibiotics. The mathematical models that have been used to simulate experimental data have been discussed. Emulsion liquid membrane and supported liquid membrane could provide high extraction flux for cephalosporins, but stability problems need to be fully resolved for process application. Non-dispersive extraction in hollow fiber membrane is likely to offer an attractive alternative in this respect. The applicability of the liquid membrane process has been discussed from process engineering and design considerations.

Adenoid cystic carcinoma - Clinical presentation and cytological diagnosis.

Adenoid cystic carcinoma is a tumor arising from the minor salivary glands, the palate being the commonest site. It accounts for about 1% of all head and neck malignancies. We report a case with the typical presentation of a palatal growth with extensive intra-cranial invasion. The diagnosis of this case and a brief review of literature is discussed. Final diagnosis of this case was made from cytological reports. The dry smears stained with MGG were found to be definitely superior to the alcohol fixed slides stained with papanicolaou. The aim here is to highlight the importance of cytology in the diagnosis of such tumors.

Tonsillectomy using harmonic scalpel.

Surgery of tonsils are associated with risk of haemorrhage and post operative pain. Harmonic scalpel is a new device which we have been using to perform tonsillectomy for the last one year. This instrument reduces dissection time, intra-operative bleeding and post operative pain.

Coordinate production of cephamycin c and clavulanic acid by Streptomyces clavuligerus.

Production of cephamycin c and clavulanic acid by Streptomyces clavuligerus was investigated using different media in shake flask condition. Highest cell growth (3.8 g/L) was observed in glycerol, sucrose, proline and glutamic acid (GSPG) medium. Although, GSPG medium supported maximum growth, it was least effective for the synthesis of both cephamycin and clavulanic acid. Yield of cephamycin and clavulanic acid was maximum in dextrin and K medium, respectively. High and low level of constituents of dextrin medium, affected production of both cephamycin and clavulanic acid. Biosynthesis of clavulanic acid was associated with production of cephamycin c.

Extraction and purification of cephalosporin antibiotics.

The biologically active natural and semisynthetic cephalosporin antibiotics require proper methods of extraction and purification for their isolation and subsequent pharmacological studies. This article reviews the various methods useful for extraction and purification of individual compounds as well as the enzymes involved in their biosynthesis. Applicability of the methods for downstream processing of the spent medium has been critically analysed. Adsorption chromatography, particularly with reverse phase materials, in combination with membrane separation is the most successful technique for extraction as well as purification of most of the enzymes and individual compounds. Techniques such as reactive extraction in liquid membrane, non-dispersive extraction in hollow fiber membrane and aqueous two-phase extraction are likely to emerge in new generation processes. Finally, some aspects of process design and scale-up have been discussed, highlighting the research needs of pragmatic importance.

Developments in liquid membrane separation of beta-lactam antibiotics.

This paper presents an overview on the developments in liquid membrane separation and purification of commercially important beta-lactam antibiotics. Reactive extraction via liquid-liquid ion exchange or ion-pair extraction mechanism can be exploited to develop liquid membrane processes for separation and concentration of penicillins and cephalosporins. Because of high selectivity and flux, liquid membrane processes can be adopted for direct extraction of beta-lactams from fermentation broth. Other advantages of liquid membrane technologies are low capital and operating costs, compact unit installation in commercial plants, low material inventory, etc. Both emulsion liquid membrane and supported liquid membrane techniques can be effective under the reactive extraction conditions. However, the stability problems of liquid membrane should be resolved before commercial application can be established. Alternately, reactive extraction in non-dispersive mode with hollow fiber membranes can be an attractive and viable strategy for practical application. Applicability of the liquid membrane processes has been discussed from process engineering and design considerations.