Parallel transmission RF pulse design with strict temperature constraints

RF safety in parallel transmission (pTx) is generally ensured by imposing specific absorption rate (SAR) limits during pTx RF pulse design. There is increasing interest in using temperature to ensure safety in MRI. In this work, we present a local temperature correlation matrix formalism and apply it to impose strict constraints on maximum absolute temperature in pTx RF pulse design for head and hip regions. Electromagnetic field simulations were performed on the head and hip of virtual body models. Temperature correlation matrices were calculated for four different exposure durations ranging between 6 and 24 min using simulated fields and body‐specific constants. Parallel transmission RF pulses were designed using either SAR or temperature constraints, and compared with each other and unconstrained RF pulse design in terms of excitation fidelity and safety. The use of temperature correlation matrices resulted in better excitation fidelity compared with the use of SAR in parallel transmission RF pulse design (for the 6 min exposure period, 8.8% versus 21.0% for the head and 28.0% versus 32.2% for the hip region). As RF exposure duration increases (from 6 min to 24 min), the benefit of using temperature correlation matrices on RF pulse design diminishes. However, the safety of the subject is always guaranteed (the maximum temperature was equal to 39°C). This trend was observed in both head and hip regions, where the perfusion rates are very different.     

Quenching of intracellular ROS generation as a mechanism for oleate-induced reduction of endothelial activation and early atherogenesis

We previously showed that the exposure of vascular endothelium to oleate results in reduced endothelial activation. We now investigate possible mechanisms for this effect in relation to generation of reactive oxygen species (ROS). We stimulated several types of endothelial cells with cytokines or lipopolysaccharide, with or without preincubation with 10-100 mumol/L oleate. Oleate preincubation reduced VCAM-1 expression in all cell types, as well as macrophage-colony stimulating factor release. We simultaneously measured the concentration of intracellular glutathione (GSH), the activity of GSH-related antioxidant enzymes and the production of intracellular ROS. Stimulation of endothelial cells caused a decrease of GSH and an increase in intracellular ROS. The addition of oleate before stimulation, prevented the depletion of GSH and partially prevented stimuli-induced increase of intracellular ROS. This occurred without any change in the activity of GSH-related antioxidant enzymes, superoxide dismutase and catalase. Furthermore, in a cell-free superoxide anion-generating system, oleate quenched the generation of ROS. These results indicate that oleate may exert direct vascular atheroprotective effects by inhibiting endothelial activation through a quenching of stimuli-induced increase in ROS.     

Homocysteine in chronic renal failure in relation to renal anemia and to oxidative stress parameters 4-hydroxynonenal and malondialdehyde

Homocysteine serum levels were measured in patients with end-stage renal disease in relation to severity of renal anemia and oxidative stress parameters such as 4-hydroxynonenal (HNE) and malondialdehyde (MDA). The predialytic homocysteine serum levels of the patients are five times as high as in healthy controls. It was found that homocysteine does not correlate to hemoglobin concentration and to oxidative stress, but rather to parameters of nutrition status such as albumine concentration and protein catabolic rate. The homocysteine accumulation represents a cardiovascular risk factor which is statistically independent of oxidative stress, but dependent on nutrition or energy status in patients with chronic renal failure.     

The Bengmark tube in surgical practice and in the critically ill patient

Enteral nutrition (EN) is increasingly used to minimize the rate of septic complications related to bacterial translocation, due to its effectiveness and low cost. Bengmark's self-propelling auto-positioning feeding tube (SPT) absorbs and uses gut motility for rapid transport to the upper small intestine, thereby allowing uninterrupted EN both in surgical and critically ill patients. We report on our experience with 175 SPTs applied over the period from December 1996 to February 2000, and analyse the safety, compliance, and indications of SPT in surgical and ICU practice. Open study: feasibility of insertion, time and rate of placement, compliance and complications related to the tube or to EN were studied. SPTs were successfully placed in 40 patients before liver resection, in 32 patients before extensive maxillo-facial surgery MFS and prior to colon resections in 10 cases. SPTs were also applied in 56 patients with acute vascular neurological diseases, 22 in pancreatic diseases and in another 15 critically ill patients. 92.5% of SPT's crossed the pylorus, while only 7.5% stopped in the stomach and 3.4% in the duodenum; 89.14% reached the first jejunal loop. The tip of the tube reached its final position within a mean period of 5.2 hours, 8% instantly and all within 24 hours. Enteral nutrition was started immediately after introduction of the tube into the stomach. The compliance was excellent, even in maxillo-facial surgery patients: only 2/76 patients (2.6%) showed poor compliance. There were no cases of aspiration pneumonia or other complications related to SPT. Polymeric nutrition was usually supplied at a starting flow rate of 45 ml/hour and rapidly increasing over the following 48 h. Eleven patients experienced diarrhoea and 6 abdominal distension, leading to a temporary reduction of the EN flow rate. Clogging of the SPT occurred in 13 patients: 7/13 were cleansed with pancreatic enzymes, but 6 had to be replaced. SPT is ideal for intensive EN and is characterised by minimal complications and excellent patient compliance.     

Bone marrow aspirate on the 14th day of induction treatment as a prognostic tool in de novo adult acute myeloid leukemia

BACKGROUND AND OBJECTIVES: In adult acute myeloid leukemia (AML), a variety of clinical and biological parameters have been examined for their potential value in predicting treatment response. Early response to induction therapy could be an important prognostic factor in this disease. DESIGN AND METHODS: We studied the relationship between reduced blasts in bone marrow aspirate on the 14th day (BMA14th) of induction chemotherapy and treatment outcome in 198 adult AML patients of whom 124 were < 60 years old (group A) and 74 > or = 60 years old (group B). Receiver operating characteristic curve analysis was used to assess the prognostic performance of BMA14th. Using the percentages of blasts of < or = 22% and < or = 15% as criteria for predicting treatment outcome gave the highest accuracy in terms of sensitivity and specificity in groups A and B, respectively. RESULTS: In group A, of 97 patients with a BMA14th < or = 22%, 77 (79%) achieved complete remission (CR), whereas of 27 patients with a BMA14th > 22%, 22 (81%) were non-responders (NR) (p < 0.0001). The test sensitivity and specificity were 93.9% and 71.4%, respectively. In group B, of 27 patients with a BMA14th < or = 15%, 18 (67%) achieved CR, whereas of 47 patients with a BMA14th >15%, 38 (81%) were NR (p = 0.0001). The test sensitivity and specificity were 66.7% and 80.9%, respectively. INTERPRETATION AND CONCLUSIONS: Our data suggest that BMA14th may be a predictive test for CR, helping to identify NR patients early in their disease. Further studies are needed to establish the practical implications of the results of our study.     

Oxidative stress in cardio renal anemia syndrome: correlations and therapeutic possibilities

Cardiovascular injury has been shown to be the most critical factor affecting quality of life and mortality in patients suffering from chronic renal failure. Oxidative stress has been thought to be an important risk factor for cardiovascular disorders. As oxidative stress parameters with high cardiovascular risk factor 4-hydroxynonenal and other aldehydic lipid peroxidation products, F2-isoprostanes, homocysteine, and cholesterol oxidation products were measured in chronic renal failure patients. 4-Hydroxynonenal and some cholesterol oxidation products correlated well with the degree of renal anemia. F2-isoprostane levels were related to inflammation, whereas homocysteine was increased due to malnutrition. Further, cholesterol oxidation products correlated well with the consumption of lipophilic antioxidants such as alpha-tocopherol. There was an almost linear correlation between the left ventricular mass index and 4-hydroxynonenal. Both parameters furthermore showed an inverse relationship to hemoglobin concentration. The correction of renal anemia by means of erythropoietin therapy led to an efficient strengthening of the antioxidative defence system. The improvement of the antioxidative capacity is of complex nature comprising both enzymatic pathways and low molecular antioxidants. The correction of renal anemia with its well documented reduction of the cardiovascular risk can be regarded as an antioxidative therapy, demonstrating the clinical efficiency of antioxidative protection in patients with chronic renal failure.     

Concomitant primary polycythemia vera and follicle center cell non-Hodgkin lymphoma: a case report and review of the literature

The association of myeloproliferative and lymphoproliferative disorders is well known after cytotoxic drug or radiation exposure, while it is remarkably rare prior to therapy. We report on a patient simultaneously diagnosed as having polycythemia vera and II3A follicle center cell non-Hodgkin lymphoma (grade 1). At this timepoint, he is on 12-year follow-up, characterized by post-polycythemia myeloid metaplasia with myelofibrosis and persistent complete remission of lymphoma. The conventional marrow cytogenetic analysis performed during the course of the disease demonstrated an abnormal karyotype with deletion of the long arm of chromosome 20 and trisomy 8, while molecular analysis failed to detect BCR-ABL rearrangement in peripheral blood cells. To the best of our knowledge based on a computer-aided review of the literature (MED-LINE 1966-2002), this is the sixth case of concomitant primary polycythemia vera and lymphoma of non-Hodgkin type. Besides, there is a single literature report on polycythemia vera coexisting with the Hodgkin's lymphoma. In our case as well as in the recorded ones, two independent malignant clones of myeloid and lymphoid origin, respectively, seem to have arisen. Further reports, supported by chromosomal and molecular studies, could improve our knowledge on this extremely infrequent disease association.     

Tarlov cysts: clinical evaluation of an italian cohort of patients

Tarlov cyst syndrome is a rare, often asymptomatic disorder, characterised by isolated or multiple nerve-root cysts, usually occurring in the sacral spine, near the dorsal root ganglion, between the perineurium and endoneurium. The cysts may cause lower back pain, sacral radiculopathy, dyspareunia and urinary incontinence. There is little data in the literature on the relationship between Tarlov cysts and symptoms. Here, we report further details on the clinical impact of Tarlov cysts and investigate their pathogenesis and role as a cause of lumbosacral symptoms. We examined 157 patients with MRI evidence of symptomatic Tarlov cysts. Patients underwent complete neurological examination and were scored by the Hamilton Depression Rating Scale and the Visual Analogue Scale. Complete lower limb electromyography was performed in 32 patients. Clinical picture was correlated with size and number of cysts detected by MRI. Family history was recorded for signs of genetic inheritance. Almost all patients suffered perineal or lower back pain; 34 complained of sphincter and 46 of sexual disorders. Hamilton scores were abnormal, and family history was positive in a few cases. The scanty literature on Tarlov cysts mainly regards therapy by a neurosurgical approach. Our results provide new data on clinical impact and possible pathogenetic mechanisms.     

Improvement of myocardial performance (Tei) index closely reflects intrinsic improvement of cardiac function: assessment in revascularized hibernating myocardium

Background: Myocardial performance index (MPI), or Tei index, is an indicator of systolic and diastolic myocardial function. MPI increases in case of cardiac dysfunction; however, whether reversal of left ventricular dysfunction is also reflected by concomitant improvement (i.e., decrease) of MPI is unknown. Methods: Fifty‐two patients with chronic ischemic cardiomyopathy and viable myocardium by dobutamine stress echocardiography were studied by echocardiography before and more than 4 months after cardiac revascularization. Patients were in optimal medical therapy, which remained unchanged following revascularization. Results: At baseline, ejection fraction (EF: 32 ± 6%) and wall motion score index (WMSI: 2.37 ± 0.32) were impaired, and MPI averaged 0.71 ± 0.19. Revascularization markedly improved EF (44 ± 10%, P < 0.0001) and WMSI (1.77 ± 0.44, P < 0.0001). MPI also improved (0.59 ± 0.26, P < 0.0001), and its decrease was significantly correlated with the improvement in EF (r =?0.68, P < 0.0001) and to the extent of viable myocardium (r =?0.45, P = 0.0007). Responders to revascularization (≥5% increase in EF at follow‐up, n = 40% and 77%) achieved a significant improvement in MPI at follow‐up in contrast with nonresponders (?23 ± 25% vs. 0.02 ± 0.18%, P = 0.001). Improvement in MPI was largely driven by a significant reduction in isovolumic contraction time (P < 0.001) with consequent prolongation of the ejection phase. Conclusion: In patients with chronic ischemic cardiomyopathy, MPI improves along with recovery of function, reflecting the intrinsic improvement of viable segments induced by revascularization. (Echocardiography 2012;29:298‐306)