Pulse sequence optimization for MR imaging using a paramagnetic hepatobiliary contrast agent

Paramagnetic agents enhance contrast between tissues in magnetic resonance (MR) imaging by altering tissue relaxation times. The effect of these changes on MR image intensity depends in part on the choice of operator-controlled pulse sequence parameters. With the newly described paramagnetic hepatobiliary contrast agent, iron(III) ethylenebis-(2-hydroxyphenylglycine), Fe(EHPG)-, an in vivo experimental analysis of pulse sequence optimization was performed on the rat. We compared the enhancement of the liver divided by background noise, EL/N, of standard inversion-recovery (IR) and spin-echo (SE) T1-weighted pulse sequences and several pulse sequences theoretically predicted to have improved EL/N. Optimization of the echo time (TE = TEmin) gave a substantial (greater than 60%) increase in EL/N over the standard IR and SE pulse sequences. Images obtained with optimized repetition rate and inversion time gave only a slight additional improvement. Within the uncertainties of our relaxation measurements, the measured changes in EL/N with pulse sequence optimization corresponded well with theoretical predictions. With the experimental and theoretical data, the importance of using a short echo time to obtain maximal T1 contrast in contrast-enhanced MR imaging and the relative merits of optimized SE versus IR pulse sequences for contrast-enhanced MR imaging are discussed.     

Radiation treatment of urinary bladder carcinoma

Summary A series of 602 patients with verified urinary bladder cancer have been treated with full irradiation in the period 1957–1970. As expected, the survival rate decreased with increasing stage of the tumour. Another group was randomized and treated according to either of two fractionation schemes. This trial started in 1971 and shows that there is increased survival and tumour clearance rate with superfractionation.     

Different cardiovascular and hormonal consequences of A-V fistula in uremic patients (author's trans)

The Authors studied 11 uremic patients for whom it was necessary to make an arterio-venous (A-V) fistula for dialysis purposes. Before and after creation of the fistula, the following parameters were determined: arterial pressure (PA) heart rate (HR), peripheral vascular resistances (PVR), renin, adrenalin and nor-adrenalin blood levels. The patients were divided in two groups according to the increase of the systolic output (SO) and o the cardiac index (CI) after the fistula (1st group of 5 patients: less than 30% increase of these values as compared to those before the fistula; 2nd group: more than 30% increase. By using Wilcoxon distribution free test it was possible to demonstrate the existence of a different condition, statistically significant in the two groups. In the 1st group of older patients (P < 0.05) where the systolic pressure values were greater (P < 0.05) and the indexes of the mechanical events of the left ventricle were altered, there was an increase of heart rate (P < 0.05), a moderate reduction of PVR (P < 0.01) and a very small increase of the systolic output and cardiac index (P < 0.01). Furthermore, in the 1st group, a left ventricular hypertrophy was observed, except in one case whereas this condition was constantly absent in the patients of the 2nd group. Patients of the 1st group had high nor-adrenalin blood levels, which did not change after the significantly after the creation of the fistula. In conclusion, an A-V fistula provokes two different hemodynamic behaviours which are related to age, pressure values, myocardial performance, presence of a left ventricular hypertrophy, PVR variations, and renin and nor-adrenalin blood levels.     

Tumor necrosis factor-related apoptosis-inducing ligand alters mitochondrial membrane lipids

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been shown to have selective antitumor activity. TRAIL induces ubiquitous pathways of cell death in which caspase activation is mediated either directly or via the release of apoptogenic factors from mitochondria; however, the precise components of the mitochondrial signaling pathway have not been well defined. Notably, mitochondria constitute an important target in overcoming resistance to TRAIL in many types of tumors. Bid is considered to be fundamental in engaging mitochondria during death receptor-mediated apoptosis, but this action is dependent on mitochondrial lipids. Here, we report that TRAIL signaling induces an alteration in mitochondrial membrane lipids, particularly cardiolipin. This occurs independently of caspase activation and primes mitochondrial membranes to the proapoptotic action of Bid. We unveil a link between TRAIL signaling and alteration of membrane lipid homeostasis that occurs in parallel to apical caspase activation but does not take over the mode of cell death because of the concurrent activation of caspase-8. In particular, TRAIL-induced alteration of mitochondrial lipids follows an imbalance in the cellular homeostasis of phosphatidylcholine, which results in an elevation in diacylglycerol (DAG). Elevated DAG in turn activates the delta isoform of phospholipid-dependent serine/threonine protein kinase C, which then accelerates the cleavage of caspase-8. We also show that preservation of phosphatidylcholine homeostasis by inhibition of lipid-degrading enzymes almost completely impedes the activation of pro-caspase-9 while scarcely changing the activation of caspase-8.     

Temozolomide-induced partial response in a patient with primary diffuse leptomeningeal gliomatosis

Herein we describe the case of a patient with primary diffuse leptomeningeal gliomatosis (PDLG). After surgery and ventriculoperitoneal shunt placement, due to poor general conditions, the patient was not eligible for radiotherapy. For this reason we decided to start a systemic chemotherapy treatment with Temozolomide (150 mg/m² per day for 5 days every 4 weeks). After three cycles a partial response was achieved with a clear improvement of general conditions. In our knowledge, this is the first time that PDLG treatment with Temozolomide has been described.     

Postural adjustments in arm and leg muscles associated with isodirectional and antidirectional coupling of upper limb movements in the horizontal plane

The hypothesis that anticipatory postural adjustments (APAs) may concur in generating the directional preference experienced during limb coupled movements was tested by measuring the electromyographic and mechanic postural actions elicited when moving: (1) one single arm/hand and, (2) both limbs, iso- or antidirectionally coupled. During fast adduction of the right arm in the horizontal plane (prime mover, pectoralis Major, rPM) APAs were recorded in the contralateral lPM as well as in the right ischiocruralis (rIC) muscle. This last action was associated to a transient increase of Tz (torque around body vertical axis) in the direction opposite to arm rotation. Both the APAs in rIC and the Tz changes nearly doubled in size when arms were coupled isodirectionally (adduction of one arm and abduction on the other) while they vanished when both arms were simultaneously adducted (antidirectional coupling). Conformably, during rhythmic arm oscillations APAs and Tz were cyclically modulated when movements were isodirectional, the modulation amplitude being strongly enhanced by increasing the movement frequency. When oscillations were antidirectional neither APAs nor Tz changes were observed, even if frequency was incremented. The postural actions linked to unidirectional or cyclic movements of the hand were affected by either coupling or frequency in the same way as arm movements, albeit much smaller in size. In conclusion, during antidirectional movements APAs in prime movers are synergic with voluntary activation and no postural engagement is requested to leg muscles. Conversely, during isodirectional movements, APAs in prime movers conflict with the voluntary commands and a strong, frequency-dependent, postural effort is required to leg muscles. How these factors may co-operate in determining the preference for antidirectional coupling is discussed.     

Hand immobilization affects arm and shoulder postural control

It is a common experience, immediately after the removal of a cast or a splint, to feel motor awkwardness, which is usually attributed to muscular and joint immobilization. However, the same feeling may also be perceived after a brief period of immobilization. We provide evidence that this last effect stems from changes in the cortical organization of the focal movement as well as in the associated anticipatory postural adjustments. Indeed, these two aspects of the motor act are strongly correlated, although scaled in different manners. In fact, they are both shaped in the primary motor cortex, they both undergo similar amplitude and latency modulation and, as we will show, they are both impaired by the immobilization of the lone prime mover. Neuromuscular effects of limb immobilization are well known; however, most papers focus on changes occurring in the pathways projecting to the prime mover, which acts on the immobilized joint. Conversely, this study investigates the effect of immobilization on anticipatory postural adjustments. Indeed, we show that 12 h of wrist and fingers immobilization effectively modify anticipatory postural adjustments of the elbow and the shoulder, that is, those joints not immobilized within the fixation chain. Accordingly, the motor impairment observed after short-term immobilization most likely stems from the unbalance between anticipatory postural adjustments and the focal movement.