Model system oxidations supporting the crystal growth model of ferritin iron uptake.

Fe2+ is oxidized and taken up by ferritin or ápoferritin in the presence of dioxygen. Iodate causes Fe2+ oxidation and uptake by ferritin, but not by apoferritin. Synthetic iron polymer facilitates Fe2+ oxidation by either dioxygen or iodate. Nitrilotriacetic acid or iminodiacetic acid facilitate oxidation of Fe2+ by oxygen but not by iodate. These results support the crystal growth model of ferritin iron uptake, with iron polymer serving as a model for the ferritin core and aminocarboxylic acids mimicking the metal-binding sites of apoferritin.

Kinematic adaptations to tripedal locomotion in dogs.

Limb amputation often represents the only treatment option for canine patients with certain diseases or injuries of the appendicular system. Previous studies have investigated adaptations to tripedal locomotion in dogs but there is a lack of understanding of biomechanical compensatory mechanisms. This study evaluated the kinematic differences between quadrupedal and tripedal locomotion in nine healthy dogs running on a treadmill. The loss of the right pelvic limb was simulated using an Ehmer sling. Kinematic gait analysis included spatio-temporal comparisons of limb, joint and segment angles of the remaining pelvic and both thoracic limbs. The following key parameters were compared between quadrupedal and tripedal conditions: angles at touch-down and lift-off, minimum and maximum joint angles, plus range of motion. Significant differences in angular excursion were identified in several joints of each limb during both stance and swing phases. The most pronounced differences concerned the remaining pelvic limb, followed by the contralateral thoracic limb and, to a lesser degree, the ipsilateral thoracic limb. The thoracic limbs were, in general, more retracted, consistent with pelvic limb unloading and previous observations of bodyweight re-distribution in amputees. Proximal limb segments showed more distinct changes than distal ones. Particularly, the persistently greater anteversion of the pelvis probably affects the axial system. Overall, tripedal locomotion requires concerted kinematic adjustments of both the appendicular and axial systems, and consequently preventive, therapeutic and rehabilitative care of canine amputees should involve the whole musculoskeletal apparatus.

Utility of QT dispersion combined with the signal-averaged electrocardiogram in detecting patients susceptible to ventricular tachyarrhythmia.

A simple algorithm that combines QT dispersion with the signal-averaged electrocardiogram QRS duration provides an extremely sensitive method for predicting spontaneous or inducible ventricular tachyarrhythmias. This new algorithm may prove useful in determining which patients are at risk for ventricular tachyarrhythmia.

Clustering of mutations associated with mild Marfan-like phenotypes in the 3' region of FBN1 suggests a potential genotype-phenotype correlation.

Mutations in the gene for fibrillin-1 (FBN1) cause Marfan syndrome, a dominantly inherited disorder of connective tissue that primarily involves the cardiovascular, ocular, and skeletal systems. There is a remarkable degree of variability both within and between families with Marfan syndrome, and FBN1 mutations have also been found in a range of other related connective tissue disorders collectively termed type-1 fibrillinopathies. FBN1 mutations have been found in almost all of the 65 exons of the FBN1 gene and for the most part have been unique to one affected patient or family. Aside from the "hot spots" for the neonatal Marfan syndrome in exons 24-27 and 31-32, genotype-phenotype correlations have been slow to emerge. Here we present the results of temperature-gradient gel electrophoresis analysis of FBN1 exons 59-65. Six mutations were identified, only one of which had been previously reported. Two of the six mutations were found in patients with mild phenotypes. Taken together with other published reports, our results suggest that a sizable subset (ca. 40%) of mutations in this region is associated with mild phenotypes characterized by the lack of significant aortic pathology, compared with about 7% in the rest of the gene. In two cases, mutations affecting analogous positions within one of the 43 cbEGF modules of FBN1 are associated with mild phenotypes when found in one of the 6 C-terminal modules (encoded by exons 59-63), but are associated with classic or severe phenotypes when found in cbEGF modules elsewhere in the gene.

Radiofrequency catheter ablation as primary therapy for supraventricular tachycardia.

BACKGROUND: Initial management of patients with supraventricular tachycardias has traditionally been with medications. More recently, radiofrequency catheter ablation offers curative therapy thus obviating the need for medications with potential side effects. The purpose of this study was to evaluate radiofrequency catheter ablation as an initial strategy to cure supraventricular tachycardias. METHODS: Radiofrequency catheter ablation was attempted as the initial therapy in 49 patients with supraventricular tachycardia, 25 with atrioventricular nodal reentrant tachycardia, 20 with atrioventricular reentrant tachycardia, two with both atrioventricular nodal reentrant tachycardia and atrioventricular reentrant tachycardia, and two with atrial tachycardia. RESULTS: Supraventricular tachycardia was rendered non-inducible in 48 of 49 (98%) patients undergoing radiofrequency catheter ablation. Thirteen of 14 patients returning for follow-up electrophysiologic study at 4.9 +/- 2.2 months had no evidence of recurrence. Three patients experienced documented recurrences of supraventricular tachycardia. One of these three patient's supraventricular tachycardia was rendered non-inducible after a final ablation session, and has had no recurrence after 24 months. The other two patients await repeat ablation. Two patients required treatment for atrial fibrillation which was documented prior to ablation. There were no complications or mortality from the procedure. CONCLUSIONS: Radiofrequency catheter ablation should be considered as first line therapy for symptomatic supraventricular tachycardia.

Radiofrequency catheter ablation as primary therapy for symptomatic ventricular tachycardia.

Most applications of radiofrequency (RF) catheter ablation for treatment of ventricular tachycardia (VT) have been as a treatment of last resort. The purpose of this study was to determine the efficacy and safety of RF catheter ablation as the primary treatment for symptomatic single morphology VT. Eleven of 81 patients (14%) with inducible sustained monomorphic VT underwent RF ablation as the primary treatment. One of these 11 patients had successful RF ablation of bundle branch reentry VT and was excluded from this series. The remaining 10 patients had a mean age of 58 +/- 19 years (range 20 to 73 years), were mostly men (7 of 10 patients), and all presented with documented evidence of symptomatic sustained monomorphic VT, at a mean cycle length of 340 +/- 60 milliseconds (ms) (range 250 to 430 ms). Six patients had coronary artery disease (CAD), one had surgical repair for tetralogy of Fallot, one had surgical repair of a ventricular septal defect, and two had a normal cardiac substrate. The VT origin was mapped using a combination of activation mapping, mid-diastolic potentials, pace mapping, and concealed entrainment. A mean of 5 +/- 3 (range 2 to 11) RF applications were administered to the putative VT foci. Eight of 10 (80%) clinical VTs were successfully ablated. There were no serious complications. Patients with VT originating from the left ventricle were offered implantable cardioverter-defibrillator back-up; however, only one patient accepted this option. At a mean follow-up of 12 +/- 7 months, only one patient had a possible arrhythmia recurrence.

Implanted devices and electromagnetic interference: case presentations and review.

Electromagnetic interference can cause implanted devices (pacemakers and defibrillators) to malfunction. This article reviews four cases of device interference and provides a review of the literature, and our recommendations for managing these problems.

Clinical experience with transvenous implantable cardioverter-defibrillators for treatment of malignant ventricular arrhythmias.

The need for thoracotomy has previously limited the use of the implantable cardioverter-defibrillator. Prior investigators have shown the efficacy and reduced risk of the transvenous implantable cardioverter-defibrillator. In this study, we report our experience with the transvenous implantable cardioverter-defibrillator as a first-line system. Thirty-four patients with mean age 63.2 +/- 10.3 years and mean ejection fraction 32.6 +/- 11.4% underwent implantation of a transvenous cardioverter-defibrillator using an Endotak lead with or without a subcutaneous patch. Twenty-one patients received a biphasic device and the remainder a monophasic device. Thirty-three of 34 patients (97%) were successfully implanted. The mean defibrillation threshold was than < or = 15.3 +/- 3.6J. Overall, 25 of 34 (74%) patients were implanted with a single endocardial lead alone. In the group receiving a biphasic device 19 of 21 (90%) were successfully implanted with a single endocardial lead alone whereas in the group receiving a monophasic device only 6 of 12 (50%) were successfully implanted with single endocardial lead alone (p < 0.05). There were no serious complications. One postoperative death was a result of end-staged congestive heart failure. We conclude that the transvenous implantable cardioverter-defibrillator is safe and efficacious and that incorporation of biphasic waveform may lead to higher rates of implantation of single transvenous lead alone without the need for subcutaneous patch.

[Experimental radiologic imaging of ulnar and median nerves]. / Imagerie radiologique expérimentale des nerfs cubital et médian.

This experimental study presents a new method of neurography of the ulnar and median nerves. Subcutaneous injection of water soluble iodine contrast medium (Urotrast 75%-Krka Yugoslavia) in the vicinity of the nerve immediately followed by 12V D.C. electrostimulation resulted in proximal flow of contrast medium along the epineural space versus all other structures of the nerve trunk. On X-ray films epineural space appeared as two parallel linear shadows delineating a lucent stripe which comprises all other nerve structures. By means of this method nerve X-ray images of very high quality have been accomplished for significantly shorter time than required in other procedures. The method is harmless for the patient and easily applicable.

Computed tomography image analyzer: segmentation applying active contour models--"snakes".

Many diagnostic and therapeutic procedures depend on medical images. In order to overcome imperfections of obtained images which are due to acquisition process and to obtain new information from available images, many techniques have been developed. In this study relatively new method of image segmentation, active contour model--"snakes" was applied in analyzing computed tomography (CT) images in patients with acute head trauma. Using this method, lesion to brain (LBR) and ventricle to brain ratio (VBR) were obtained accurately. Quantitative variable LBR, is significantly higher in patients with other pathologic CT findings and who do not survive during hospitalization. Thus, by applying segmentation "snakes" model it is possible to extract maximum information from available CT scans. These variables could be basis for medical decision making in patients with acute head trauma.

Ground reaction force adaptations to tripedal locomotion in dogs.

To gain insight into the adaptive mechanisms to tripedal locomotion and increase understanding of the biomechanical consequences of limb amputation, this study investigated kinetic and temporal gait parameters in dogs before and after the loss of a hindlimb was simulated. Nine clinically sound Beagle dogs trotted on an instrumented treadmill and the ground reaction forces as well as the footfall patterns were compared between quadrupedal and tripedal locomotion. Stride and stance durations decreased significantly in all limbs when the dogs ambulated tripedally, while relative stance duration increased. Both vertical and craniocaudal forces were significantly different in the remaining hindlimb. In the forelimbs, propulsive force increased in the contralateral and decreased in the ipsilateral limb, while the vertical forces were unchanged (except for mean force in the contralateral limb). Bodyweight was shifted to the contralateral and cranial body side so that each limb bore ~33% of the dog's bodyweight. The observed changes in the craniocaudal forces and the vertical impulse ratio between the fore- and hindlimbs suggest that a nose-up pitching moment occurs during the affected limb pair's functional step. To regain pitch balance for a given stride cycle, a nose-down pitching moment is exerted when the intact limb pair supports the body. These kinetic changes indicate a compensatory mechanism in which the unaffected diagonal limb pair is involved. Therefore, the intact support pair of limbs should be monitored closely in canine hindlimb amputees.

Unusual intra-arterial communication in the normal right coronary tree.

Among 136 patients with a history of angina pectoris who underwent selective coronary arteriography, two patients (1.4%) with a normal right coronary artery were found to have angiographically demonstrated communications between the various branches of the same coronary artery. Such findings, unaccompanied by coronary artery disease, have been hitherto unknown and suggest a congenital variation in coronary anatomy rather than a clinically significant condition. The purpose of this report is to demonstrate that the angiographic appearance of the anastomotic vessels in such cases is entirely different from that which obtains in cases of obstructive coronary artery disease. The author notes the rarity of angiographic visualization of homocoronary communications in normal right coronary arteries and emphasizes the necessity of distinguishing these from the homocoronary collaterals found in atherosclerotic coronary artery disease.

[Unusual metastatic shadows in the lungs and mediastinum]. / Neuobicajene metastatske senke u plucima i medijastinumu.

A wide spectrum of malignomas may develop calcified or ossified pulmonary changes of different appearance, thin or thick walled air containing cavities, or calcifications in the mediastinal lymph nodes. These unusual radiographical manifestations of metastatic deposits in the lung and mediastinum may be misdiagnosed as benign lesions what is a reason for considerate evaluation of these findings.

Neurography using the intramuscular injection of ionic iodine contrast media.

Our report presents a new method of neurography. Sciatic nerve and lumbosacral plexuses in frogs have been visualized after the intramuscular injection of water and lipid soluble ionic iodine contrast media (Telebrix 300, Potassium Iodide 30% and Lipiodol Ultra Fluid). The ascendant flow of the iodine ions (anions) has been achieved by establishing the electrical potential difference between the injection site and the proximal part of the sciatic nerve and lumbosacral plexus. The application of DC current ensued immediately after the injection. Several minutes later the proximal segments of tibial and peroneal common nerves, as well as the sciatic nerve in its full length, have been visualized on X-Ray film. Lumbosacral plexuses became radioopaque after 20 plus minutes.

Prenatal diagnosis of ventriculocoronary arterial fistula in a fetus with hypoplastic left heart syndrome and aortic atresia.

In a fetus with a hypoplastic left heart syndrome detected at 26 weeks' gestation, a communication between the left ventricular cavity and the left coronary artery was detected using color Doppler. Bidirectional flow was demonstrated and the ventricle was shown to be filled via the fistula during diastole. After premature birth at 31 weeks and neonatal death, autopsy confirmed the findings. Because the association of a heart defect with ventriculocoronary communications worsens the neonatal prognosis, it should be ruled out in fetuses with hypoplastic left heart syndrome before parents are counseled.