Gallium-67 lung uptake: conjugate-view technique

A conjugate-view technique is derived for calculation of absolute gallium-67 (Ga-67) uptake from scintillation-camera images. The technique combines counts of posterior and anterior images of the lung with an attenuation correction obtained from cobalt-57 (Co-57) transmission imaging. The formulation is such that the effects of Compton scatter build-up are accounted for. Studies utilizing a canine model indicated that, normally, more activity is located in the chest wall than in the lungs. The quantitative technique must therefore accurately account for a variety of Ga-67 distributions, including that in the chest wall. Calculations were performed using a three-component model comparing results obtained with the conjugate-view approach to the actual uptake. These calculations suggest that an assumption of uniform activity distribution allows an accuracy of approximately +/- 10% over a broad range of body-part thicknesses and uptake by the lungs. It was concluded that the conjugate-view technique is necessarily approximate but can provide clinically useful results.     

Platelet Functions in Cardiopulmonary Bypass Surgery

Background

Haemorrhage after Cardio Pulmonary Bypass (CPB) Surgery is a well recognised complication that leads to significant morbidity and mortality. The incidence varies between 5-25% depending upon the clinical situation. Several factors are implicated as causative but none have been precisely proved.

Methods

Our study was an attempt to evaluate the haemostatic defect with particular reference to platelet function abnormalities during cardio pulmonary bypass surgery, in order to reduce the morbidity and mortality associated with post CPB haemorrhage. Flow cytometric evaluation of different platelet glycoproteins like GPIb/IX, GPIIb/IIIa and GMP-140 was done.

Results

The marker expression showed deregulation during surgery which returned to base after bypass was terminated. In contrast, the cases with bleeding showed significant variation. P-Selectin (GMP 140) expression decreased progressively till 3^rd post-operative day showing lack of activation of platelets in cases of severe bleeding.

Conclusion

Longer duration of CPB initiates plasmin generation through heparin, which raises the PAI-1-tPA complex and thereby down regulating the functions of platelets. This suggests a link between duration of CPB, bleeding, platelet dysfunction and fibrinolysis. Hence serial estimations of the levels of GMP-140 and tPA can predict severe bleeding.Key Words: CardioPulmonary Bypass, Platelet dysfunction, flowcytometry, platelet glycoproteins, haemorrhage     

A Sublingual Dermoid

Indian Journal of Otolaryngology and Head & Neck Surgery - A case of Sublingual Dermoid in the floor of the mouth is presented which can be mistaken as ranula, cystic hygroma or salivary gland...     

Formulation and biopharmaceutical evaluation of osmotic matrix tablets of diclofenac sodium

The objective of our study was to prepare and evaluate osmotic matrix (OM) tablets of diclofenac sodium (DS). In vitro studies were done on USPXXIV dissolution apparatus II in different release medium. Surface characteristics of coating films and osmotic contribution of OM tablets also were studied. In vivo evaluation was carried out in 6 healthy human volunteers using HPLC method to assay plasma samples, and the results were compared with the performance of fabricated matrix and two commercial tablets of DS. Through in vitro drug release kinetics, using regression coefficient analysis and Peppas equation, different pharmacokinetic parameters and relative bioavailability were determined. OM tablets were found to provide more prolonged and controlled therapeutic plasma DS levels and also showed improved bioavailability in comparison to fabricated matrix and commercial tablets studied.     

Development and biopharmaceutical evaluation of osmotic pump tablets for controlled delivery of diclofenac sodium

Based on the principles of an elementary osmotic pump (OP), OP tablets were designed and evaluated with the aim to deliver diclofenac sodium (DS) in a controlled manner. In vitro evaluation was done in various release media and kinetics was evaluated using the regression coefficient analysis. Effects of orifice size, coating membrane type, coating thickness, static and stirred conditions and pH variation were studied. In vivo evaluation was performed on six healthy human volunteers and various pharmacokinetic parameters (c(max), t(max), AUC(0-24), MRT) and relative bioavailability were calculated. The results were compared with the performance of two commercial tablets of DS. The drug release from OP tablets was dependent on the type and thickness of the coating membrane, but was independent of the orifice size and static and stirred conditions of the release medium. The OP tablets provided a prolonged and controlled DS release compared to commercial sustained-release and conventional tablets of DS.     

Determination of Glass Transition Temperature and in Situ Study of the Plasticizing Effect of Water by Inverse Gas Chromatography

Purpose. To use an inverse gas chromatographic (IGC) method to determine the glass transition temperature (Tg) of some amorphous pharmaceuticals and to extend this technique for the in situ study of the plasticizing effect of water on these materials. Methods. Amorphous sucrose and colyophilized sucrose-PVP mixtures were the model compounds. Both IGC and differential scanning calorimetry (DSC) were used to determine their Tg. By controlling the water vapor pressure in the IGC sample column, it was possible to determine the Tg of plasticized amorphous phases. Under identical temperatures and vapor pressures, the water uptake was independently quantified in an automated water sorption apparatus. Results. The Tg of the dry phases, determined by IGC and by DSC, were in very good agreement. With an increase in the environmental relative humidity (RH), there was a progressive decrease in Tg as a result of the plasticizing effect of water. Because the water uptake was independently quantified, it was possible to use the Gordon-Taylor equation to predict the Tg values of the plasticized materials. The predicted values were in very good agreement with those determined experimentally using IGC. A unique advantage of this technique is that it provides complete control over the sample environment and is thus ideally suited for the characterization of highly reactive amorphous phases. Conclusions. An IGC method was used (a) to determine the glass transition temperature of amorphous pharmaceuticals and (b) to quantify the plasticizing effect of water on multicomponent systems.