Turf wars in radiology: introduction

Turf wars over medical imaging have become ubiquitous. At many centers, radiologists already have lost access to important technologies and their applications. A combination of decreasing revenues in other specialties and a growing attachment to imaging further threatens radiologists’ practices in the future. This is the first of an extended series of articles that will address the phenomenon of self-referral—its motivations, extent, and the threats it poses to radiologists. Each article will focus on a specific aspect and provide advice on how radiologists can deal with self-referral in their locales.     

Extended trans-septal approach for mitral valve surgery: Our early experience

Background Extended trans septal (ETS) approach for mitral valve surgery often divides the artery to the Sino-Atrial node. The clinical implication of this is contentious. We analyzed our early results with ETS approach. Methods Between June 1998 and September 2003 eleven patients underwent mitral valve surgery by ETS approach. Six were females. Age ranged from 19 years to 67 years (median 40 years). Six underwent mitral valve replacement (MVR). Four underwent aortic and mitral (double) valve replacement (DVR). One had mitral valve repair. Three had additional procedures (tricuspid valve repair=1, Coronary artery bypass=1, Aorto bifemoral graft=1). Cardiopulmonary bypass ranged from 64 minutes to 77 minutes (median 72 minutes) for MVR and 112 minutes to 178 minutes (median 140 minutes) for DVR. Aortic cross clamp times ranged from 39 minutes to 52 minutes (median 47 minutes) for MVR and 74 minutes to 120 minutes (median 95 minutes) for DVR. Results There was no mortality or morbidity attributed to the ETS approach. One early death in emergency DVR was due to heart failure. Three patients needed seqeuntial pacing in the immediate post-operative period. Nine out of ten survivors were back to their preoperative rhythms on hospital discharge (6 sinus rhythm; 3 atrial fibrillation). One patient with preoperative trifascicular block who underwent reoperation to fix a paravalvular mitral leak needed a permanent pacemaker (VVI). The follow-up ranged from 1 month to 64 months (median 6 months) and is 100% complete. There was no late death or new arrhythmia. Conclusions Extended trans septal approach is safe. It gives excellent exposure of the mitral valve. division of the sinus node artery is not deleterious in the short to intermediate term. Presented at the 50th Annual Meeting of IACTS. New Delhi, Feb. 2004.     

Inhibition of platelet aggregation by novel triphenylethylene analogs

The present study has evaluated the effect of some newly synthesized triphenylethylene (TPE) analogs on platelet arachidonic acid metabolism and function. All compounds tested inhibited arachidonic acid induced platelet aggregation and several were superior to aspirin in their relative potency. Introduction of a carboxyl function into the alpha-ring, which should enhance binding according to proposed structural models for cyclooxygenase inhibitors, was not found to be beneficial. Increased structural rigidity, which resulted from covalent linkage of two aromatic rings in this series, did not eliminate anti-aggregatory properties.     

Interaction of calmodulin with iodothyronines: effect of iodothyronines on the calmodulin activation of cyclic AMP phosphodiesterase

The interaction between calmodulin and iodothyronines and the effect of iodothyronines on the calmodulin activation of cyclic AMP phosphodiesterase were investigated. Binding of [L-125I]triiodothyronine to calmodulin from pig brain, studied by equilibrium dialysis, was dependent on Ca2+, was saturable and reversible, with an apparent Kd of 2.79 microM and binding capacity of 0.5 nmol/20 micrograms of calmodulin L- and D-thyroxine, D-triiodothyronine and tetrac displaced [L-125I]triiodothyronine at concentrations of 8-10 microM; triac, 3,3'-diiodothyronine and reverse-triiodothyronine were weak displacers. In the presence of the antipsychotic drug trifluoperazine, binding decreased in a dose-related manner. Ultraviolet irradiation of calmodulin in the presence of trifluoperazine reduced the binding of [L-125I]triiodothyronine to calmodulin irreversibly. Calmodulin activation of cyclic AMP phosphodiesterase decreased when iodothyronines were bound to calmodulin; the calmodulin-L-triiodothyronine complex was the most active among the stereoisomers of thyroxine and triiodothyronine. These results suggest that, when triiodothyronine was bound to Ca2+-calmodulin, the activation of cyclic AMP phosphodiesterase by the latter is suppressed.     

Zero-Order Release Formulation of Oxprenolol Hydrochloride with Swelling and Erosion Control

Zero-order release of oxprenolol hydrochloride was obtained by controlling the swelling and erosion of the matrix. This formulation involves only mixing of drug, hydroxypropylmethylcellulose (HPMC), and sodium carboxymethylcellulose (Na CMC) at the ratio of 1:0.4:1.6, respectively, and compressing the mixture directly into tablets. The in vitro release pattern from this optimized matrix tablet was reproducible. Accelerated stability studies revealed that the optimized formulation remains stable for an approximately 2-year shelf life. This sustained-release (SR) tablet was evaluated in dogs, and for comparison a conventional (CV) formulation was also given at the same dose level. Plasma oxprenolol levels were monitored by a sensitive and specific high-performance liquid chromatographic (HPLC) method. Significant differences in the pharmacokinetic parameters, i.e., lower C _max, higher values of t _max, MRT, AUC, and plasma concentration at 24 hr, and nearly constant plasma levels over 12 hr, indicated that the SR matrix tablet is superior to the CV rapid-releasing formulation. The in vitro release parameters and in vivo pharmacokinetics correlated well.     

Factors affecting the use of peritoneal dialysis among the ESRD population in India: a single-center study.

OBJECTIVES: Factors such as limited health-care budget allotment and poor accessibility of the majority of the population to hemodialysis (HD) facilities should favor the use of peritoneal dialysis (PD) in India. However, only 6% of end-stage renal disease patients undergoing dialysis in India are on PD. We undertook this prospective study to evaluate various factors that could contribute to this low rate of use of PD at a tertiary-care state-run hospital in Northern India. METHODS: All the patients who entered our HD or PD program from August 2001 to December 2003 were interviewed using a preset questionnaire. The questionnaire recorded their basic disease and comorbidity, social and demographic characteristics, awareness of the various modalities of renal replacement therapy (RRT), and the reasons for choosing their present modality of therapy. Treating nephrologists were also interviewed with respect to the factors that, in their opinion, were responsible for the limited use of PD at our institute. RESULTS: In total, 342 patients on HD, 66 patients on PD, and 24 nephrologists were interviewed. The rate of PD use was 16.2%. Mean age of patients on HD and PD was 34.6 +/- 11.8 years and 62.9 +/- 10.3 years respectively (p < 0.0001). The incidence of diabetes mellitus and coronary artery disease in the HD and PD populations was 2.5% and 62.5%, and 9.1% and 46.7% respectively (p < 0.0001 for both). Only 30.4% of patients on HD were aware of PD as a modality of RRT and 83.6% of them found PD to be expensive, 65.4% had low enthusiasm toward a domiciliary therapy such as PD, and 61.5% were not recommended PD by their nephrologist. Only 5 (7.6%) patients were initiated on PD directly, the remaining 61 patients were shifted from HD after a mean duration on HD of 185.3 +/- 15.4 days: 67.1% were shifted due to poor tolerance of HD, 29.4% were advised to shift to PD because of comorbidity and vascular access problems, and only 3.3% took up PD because of the independent lifestyle it offered. None of the interviewed nephrologists routinely discussed PD in predialysis counseling. They found financial constraints (100%), lack of patient enthusiasm (100%), doubtful patient compliance (83.2%), and lack of an organized PD program (79.2%) to be the main factors limiting more widespread use of PD at our institute. CONCLUSIONS: Peritoneal dialysis is an underused modality of RRT at our institute. The patients who are taken up for PD at our institute are elderly and have a higher incidence of other comorbid conditions, such as diabetes mellitus and coronary artery disease. Also, most patients who switch to PD do so due to their unsuitability for HD rather than by their own choice. The factors contributing to this low rate of use of PD are ignorance of PD, increased cost of therapy, low enthusiasm toward domiciliary therapy, and lack of adequate infrastructure for PD at our institute. Effective predialysis counseling, reduction in the cost of the therapy, and development of an adequate infrastructure can increase the rate of use of PD.