Automated image registration of gated cardiac single-photon emission computed tomography and magnetic resonance imaging

PURPOSE: To develop an automatic registration method for electrocardiogram-gated myocardial perfusion single-photon emission computed tomography (SPECT) and cardiac cine-magnetic resonance imaging (MRI). MATERIALS AND METHODS: Paired myocardial perfusion SPECT (MPS) and MRI from 20 patients were considered. MR images were presegmented by heart localization based on detection of cardiac motion and optimal thresholding. A registration algorithm based on mutual information was subsequently applied to all time frames or a selected subset from both modalities. RESULTS: A preprocessing step significantly improved the accuracy of the registration when compared to automatic registration performed without preprocessing. Errors in translation parameters (T(x), T(y), T(z)) averaged (1.0 +/- 1.5, 1.1 +/- 1.3, 0.9 +/- 0.9) pixels with MRI segmentation and (4.6 +/- 3.2, 3.4 +/- 2.6, 3.0 +/- 3.4) pixels without MRI segmentation. Errors in rotation parameters (R(x), R(y), R(z)) averaged (5.4 +/- 2.9, 3.4 +/- 2.7, 4.5 +/- 3.6) degrees with MRI segmentation and (9.3 +/- 6.1, 4.8 +/- 4.3, 14.6 +/- 12.6) degrees without MRI segmentation. Error was calculated as the absolute difference between the expert manual and the automatic registration transformation. CONCLUSION: Automatic registration of gated MPS and cine MRI is possible with the use of a mutual information-based technique when MR images are presegmented. Cardiac motion can be used to isolate the left ventricle (LV) on the MR images automatically, and subsequently the segmented MR images can be coregistered with gated MPS.     

Pharmacokinetics of erythromycin in rabbit corneas after single-dose infusion: role of P-glycoprotein as a barrier to in vivo ocular drug absorption

Efflux pump like P-glycoprotein (P-gp) is known to be a major barrier to drug delivery. Functional P-glycoprotein has been recently identified in cornea and corneal cell lines. Thus, it is probable that P-glycoprotein may restrict in vivo ocular drug absorption, resulting in low ocular bioavailability. Experiments were designed using New Zealand albino (New Zealand White) rabbits to assess inhibitors of P-gp efflux to increase drug absorption. Anesthetized rabbits were given constant topical infusions of [(14)C]erythromycin in the presence and absence of inhibitors. Testosterone, verapamil, quinidine, and cyclosporine A were selected as P-gp inhibitors. Transport experiments were conducted in Madin-Darby canine kidney cells transfected with the human mdr1 gene (MDCK-MDR1). Erythromycin exhibited significant efflux out of MDCK-MDR1 cells, suggesting that erythromycin is a good substrate for P-gp. Ocular pharmacokinetic studies were conducted using a topical single-dose infusion method. Maximum inhibition of P-gp mediated efflux was observed with 500 microM testosterone. Area under the curve (AUC)(0- infinity ) of erythromycin with 500 microM testosterone was almost 4 times higher than AUC(0- infinity ) without any inhibitor. Rate of elimination (k(10)) for erythromycin and those with inhibitors was found to be similar (141 +/- 23 min), suggesting that elimination pathways were not altered. All the inhibitors were found to be nontoxic. Verapamil also inhibited the efflux pump with moderate change in AUC(0- infinity ) and C(max) compared with control. Thus, P-gp is found to be active in vivo, and it restricts topical erythromycin absorption across the cornea, which can be inhibited by known P-gp inhibitors. Therefore, ocular bioavailability of P-gp substrates can be significantly enhanced by proper selection of P-gp inhibitors.     

A new tool for measurement of process-based performance of multispecialty tertiary care hospitals

There is an increasing need of a model for the process-based performance measurement of multispecialty tertiary care hospitals for quality improvement. Analytic hierarchy process (AHP) is utilized in this study to evolve such a model. Each step in the model was derived by group-discussions and brainstorming sessions among experienced clinicians and managers. This tool was applied to two tertiary care teaching hospitals in Barbados and India. The model enabled identification of specific areas where neither hospital performed very well, and helped to suggest recommendations to improve those areas. AHP is recommended as a valuable tool to measure the process-based performance of multispecialty tertiary care hospitals.     

Alternative therapies for male and female sexual dysfunction

Sexual dysfunction is prevalent in both men and women. Although new pharmaceutical agents have been identified for male erectile problems, sexual desire and orgasm disorders, individuals with sexual dysfunction often seek alternative therapies, including traditional Chinese medicine. This article reviews currently used alternative therapies, such as herbal medications, L-arginine, acupuncture, biofeedback and others. Potential herb-drug interactions are also presented.     

Apolipoprotein E gene polymorphism in Indian patients with Alzheimer's disease and vascular dementia

The association of apolipoprotein E (ApoE) gene polymorphism with Alzheimer's disease (AD) has been reported in several populations including one from a rural community in North India. However, the association of ApoE polymorphism with vascular dementia (VaD) is yet to be established in this population. In a case-control study involving 54 cases of dementia (29 AD and 25 VaD) and 76 age-matched healthy controls, the frequency of epsilon4 allele was significantly higher among cases of AD and VaD compared with controls (p < 0.001). The epsilon3epsilon3 (p < 0.05) and epsilon2epsilon3 (p < 0.001) genotypes were found to be protective. The odds of developing AD or VaD were 4.4 and 3.7 times higher, respectively, in the presence of even a single epsilon4 allele. Our results suggest that the increased risk of developing AD or VaD is similar among Asian Indians with ApoE epsilon4 compared with the Caucasian population.     

Synthesis,characterization, and blood compatibility of polyamidoamines copolymers

This work reports the development of new non-thrombogenic polymers based on the linear polymers of polyamidoamines (PAAs), having heparin binding ability, obtained by polyaddition of secondary amines to N,N'-methylene bis-acrylamide. PAAs could not be used directly in the making of blood-contacting materials due to their poor mechanical strength. In order to overcome this lacuna, copolymers of amidoamine with methylmethacrylate (MMA) were prepared. Characterization studies indicated that the PAAs have been suitably incorporated into the MMA matrix. The relative hydrophilic nature of the synthesized copolymers was established from the measurement of water contact angle. The heparinized copolymers showed significant improvement in non-thrombogenic characteristics.     

Zinc in CSF of patients with febrile convulsion

OBJECTIVE: This prospective study was carried out from July-December 1999 to see the status of zinc in CSF of children with febrile convulsion and to compare this to that of control. METHODS: Forty-two cases of febrile convulsion and 30 controls (fever without convulsion) were enrolled into the study. CSF zinc was estimated by atomic absorption spectrophotometry (AAS) in Atomic Energy Center, Dhaka and compared between the two groups. RESULTS: The mean zinc level in CSF in the study sample was 40.19mgm/L and that in control was 74.98mgm/L. This difference was statistically significant (p<0.001). CONCLUSION: The study concludes that a significantly lower of zinc exists in CSF of children with febrile. However no relationship was found between CSF zinc status with age, sex, degree & duration of fever and time of lumbar puncture after convulsion.