Hybrid Repair of an Acute Type B Dissection with Subclavian‐to‐Subclavian Bypass and Stent‐Grafting

Abstract Hybrid repair of an acute type B aortic dissection with endovascular stenting and aortic arch debranching is an acceptable treatment in complicated type B dissection. We present the case of a 71‐year‐old man presenting with acute type B aortic dissection and concomitant aneurysm of the distal aortic arch, who underwent an uneventful hybrid procedure, which involved subclavian‐to‐subclavian bypass before endovascular stent‐graft placement to the aortic arch. (J Card Surg 2010;25:336‐339)     

Is a filum terminale with a normal appearance really normal?

INTRODUCTION. Tethered spinal cord is defined as a condition in which the conus medullaris ends at a level below the L1-2 intervertebral space. The spinal cord is considered to be tethered when there is a thick filum terminale or low-lying conus medullaris. It has also been reported that a normal level of the conus medullaris and normal thickness of the filum terminale do not mean that there is no cord tethering. MATERIALS AND METHODS. In this investigation, we examined 21 fila terminalia; 5 of them were taken from cadavers, and these were used as a control group (group 1; n/n), 8 from patients with a normal appearance of the filum terminale but with clinical symptoms (incontinence) and pathologic results of a urodynamic study (group 2; n/ab), and 8 from patients with an abnormal appearance of the filum terminale and with clinical symptoms (group 3; ab/ab). Interestingly, we found that while fila terminalia in the control group were made up mainly of collagen fibers, more connective tissue with dense collagen fibers, some hyalinization and dilated capillaries were noticed in the fila from group 2. RESULTS. Our results suggest that these histological features may reflect a decreased elasticity within the filum terminale, resulting in a tethering effect on the lower conus in otherwise normal physiological conditions. CONCLUSION. These findings lead us to reconsider sectioning of the filum terminale in incontinent patients with normal results in radiological studies, whose condition is called "nonneurogenic neurogenic bladder."     

A mixture of experts network structure for modelling Doppler ultrasound blood flow signals

Mixture of experts (ME) is a modular neural network architecture for supervised learning. This paper illustrates the use of ME network structure to guide modelling Doppler ultrasound blood flow signals. Expectation-Maximization (EM) algorithm was used for training the ME so that the learning process is decoupled in a manner that fits well with the modular structure. The ophthalmic and internal carotid arterial Doppler signals were decomposed into time-frequency representations using discrete wavelet transform and statistical features were calculated to depict their distribution. The ME network structures were implemented for diagnosis of ophthalmic and internal carotid arterial disorders using the statistical features as inputs. To improve diagnostic accuracy, the outputs of expert networks were combined by a gating network simultaneously trained in order to stochastically select the expert that is performing the best at solving the problem. The ME network structure achieved accuracy rates which were higher than that of the stand-alone neural network models.     

Detecting variability of internal carotid arterial Doppler signals by Lyapunov exponents

The new method presented in this study was directly based on the consideration that internal carotid arterial Doppler signals are chaotic signals. This consideration was tested successfully using the nonlinear dynamics tools, like the computation of Lyapunov exponents. Multilayer perceptron neural network (MLPNN) architecture was formulated and used as a basis for detecting variabilities such as stenosis and occlusion in the physical state of internal carotid arterial Doppler signals. The computed Lyapunov exponents of the internal carotid arterial Doppler signals were used as inputs of the MLPNN. Receiver operating characteristic (ROC) curve was used to assess the performance of the detection process. The internal carotid arterial Doppler signals were classified with the accuracy varying from 94.87% to 97.44%. The results confirmed that the proposed MLPNN trained with Levenberg-Marquardt algorithm has potential in detecting stenosis and occlusion in internal carotid arteries.     

Increased thalamocortical synaptic response and decreased layer IV innervation in GAP-43 knockout mice

The growth-associated protein, GAP-43, is an axonally localized neuronal protein with high expression in the developing brain and in regenerating neurites. Mice that lack GAP-43 (GAP-43 -/-) fail to form a whisker-related barrel map. In this study, we use GAP-43 -/- mice to examine GAP-43 synaptic function in the context of thalamocortical synapse development and cortical barrel map formation. Examination of thalamocortical synaptic currents in an acute brain slice preparation and in autaptic thalamic neurons reveals that GAP-43 -/- synapses have larger alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate receptor (AMPAR)-mediated currents than controls despite similar AMPAR function and normal probability of vesicular release. Interestingly, GAP-43 -/- synapses are less sensitive to blockade by a competitive glutamate receptor antagonist, suggesting higher levels of neurotransmitter in the cleft during synaptic transmission. Field excitatory postsynaptic potentials (EPSPs) from GAP-43 -/- thalamocortical synapses reveal a reduced fiber response, and anatomical analysis shows reduced thalamic innervation of barrel cortex in GAP-43 -/- mice. Despite this fact synaptic responses in the field EPSPs are similar in GAP-43 -/- mice and wild-type littermate controls, and the ratio of AMPAR-mediated to N-methyl-d-aspartate receptor (NMDAR)-mediated currents (AMPAR:NMDAR ratio) is larger than normal. This suggests that GAP-43 -/- mice form fewer thalamocortical synapses in layer IV because of decreased anatomical innervation of the cortex, but the remaining contacts are individually stronger possibly due to increased neurotransmitter concentration in the synaptic cleft. Together, these results indicate that in addition to its well known role in axonal pathfinding GAP-43 plays a functional role in regulating neurotransmitter release.     

Comparative morphological differences between umbilical cords from chronic hypertensive and preeclamptic pregnancies

To compare morphological changes in the umbilical cords from chronic hypertensive and preeclamptic patients having normal or pathological umbilical artery Doppler ultrasonographic results. Umbilical cords from 34 normotensive, 31 chronic hypertensive and 70 preeclamptic women with normal and abnormal Doppler flow velocity waveforms (FVW) at 35-40 gestational weeks were studied. Morphological changes in the umbilical cords were examined on formalin-fixed, paraffin-embedded sections. The total umbilical cord area, total vessel area, and wall thickness of umbilical vessels were measured in systematic random samples using unbiased stereology methods. An ANOVA test was used for statistical analysis. In the chronic hypertensive and preeclamptic groups with normal Doppler FVW, the thickness of the umbilical cord vessels remained nearly constant, whereas both the total area and the lumen area were reduced. These changes correlate with the histopathological findings, suggesting a mainly vasoconstrictive effect. By contrast, analysis of the preeclamptic group with pathologic Doppler FVW showed a comparable reduction of all parameters of the umbilical cord. Histopathological findings were related to smaller, contracted smooth muscle cells of the vessel wall, which is suggestive of a predominant hypoplastic mechanism. As a result of reduced uteroplacental perfusion, fetal hypoxia and intrauterine growth retardation become unavoidable in preeclampsia. The histopathological changes in the umbilical cord between the chronic hypertensive and preeclamptic patients depend on the Doppler results. In conclusion, the umbilical artery Doppler FVW indices provide good values for predicting intrauterine growth retardation in preeclamptic patients.     

The effect of tibolone on endometrial IGF-1 and IGFBP-1 levels in ovariectomized rats

OBJECTIVE: The goal of this study was to search the effects of two different doses of tibolone on endometrial IGF-1 and IGFBP-1 levels in ovariectomized rats. METHODS: Eighteen adult, female, 80-90-days-old, Wistar rats with an average weight of 250 g underwent bilateral ovariectomy under general anesthesia. After waiting for 4 weeks, they were randomized into three groups to receive either oral tibolone in two different doses or placebo. The treatment was continued for 5 weeks, and then the rats were sacrificed and the endometria were analyzed. RESULTS: Low columnar epithelium of the endometrial surface, longer epithelium and stratified squamous epithelium were seen in the control, low-dose and high-dose groups, respectively. The staining intensity of IGF-1 was mild in control, and moderate in both treatment groups, the difference between control the treatment groups was significant (P=0.015 for group L, and P=0.03 for group H). The staining intensity of IGFBP-1 was moderate in control, and strong in groups L and H. Again the difference was significant between control and both treatment groups (P=0.039 for grup L, and P=0.03 for group H). No significant difference was noted between each treatment group for both IGF-1 and IGFBP-1. CONCLUSION: Tibolone caused histological changes in endometrium and stimulated IGF-1 and IGFBP-1 staining. Both low and high dose treatments led to moderate and strong staining intensities for IGF-1 and IGFBP-1, respectively. The strong staining intensity of IGFBP-1 is likely due to the progestagenic effect of tibolone.     

Surgical treatment of lower limb ischemia in diabetic patients – long-term results

Introduction

Lower limb ischemia may cause nonhealing ulcers, infection, amputation and even mortality in diabetic patients. In this study, we review our data of ischemic lower limb revascularization procedures in diabetic patients and present the early, mid- and long-term results.

Material and methods

From March 2004 to September 2008, 83 patients with lower limb ischemia in Fontaine class III and IV underwent distal arterial bypass procedures. Saphenous vein grafts were used for below-knee arterial bypasses in all patients. In 16 (19%) patients femoropopliteal bypasses were performed with PTFE grafts. Short-term and long-term surgical results were evaluated.

Results

Ulcer recovery was determined in 36% of patients. Graft patency was 95% and 1 death (1%) occurred in short-term follow-up. In long-term follow-up the total effectiveness rate was 74%. Graft patency was 79% and 6 deaths (7%) occurred during the follow-up.

Conclusions

Lower limb ischemia is a serious event in patients with diabetes mellitus. The consequences may include increased mortality and morbidity in this particular patient population. However, distal arterial revascularizations are considerably effective procedures to avoid amputation, to eliminate symptoms, to promote ulcer recovery and to help the patient participate in social life with acceptable short, mid- and long-term follow-up results.     

Application of classical and model-based spectral methods to ophthalmic arterial Doppler signals with uveitis disease

In this study, Doppler signals recorded from ophthalmic artery of 75 subjects were processed by PC-computer using classical and model-based methods. The classical method (fast Fourier transform) and three model-based methods (Burg autoregressive, moving average, least-squares modified Yule–Walker autoregressive moving average methods) were selected for processing ophthalmic arterial Doppler signals with uveitis disease. Doppler power spectra of ophthalmic arterial Doppler signals were obtained by using these spectrum analysis techniques. The variations in the shape of the Doppler spectra as a function of time were presented in the form of sonograms in order to obtain medical information. These Doppler spectra and sonograms were then used to compare the applied methods in terms of their frequency resolution and the effects in determination of uveitis disease.     

Diagnosis of mixed Plasmodium malariae and P. vivax infection in a development aid volunteer by examination of bone-marrow specimens by real-time PCR

Mixed Plasmodium malariae and P. vivax infections in humans are reported very infrequently. The case of a 27-year-old male who sustained malaria quartana/tertiana caused by an unbalanced mixed P. malariae-P. vivax infection is reported here. Conventional tests and serology for malarial parasites were uniformly negative. Identification and quantification of the parasites were accomplished by examining bone-marrow specimens using specific real-time TaqMan PCR.