Transjugular intrahepatic portosystemic shunting (TIPS) with balloon-expandable and self-expanding stents: Technical and clinical aspects after 3 1/2 years’ experience

Purpose To evaluate prospectively our experience with transjugular intrahepatic portosystemic shunt (TIPS) using four different metallic stents. Methods Between November 1991 and April 1995, 57 patients (41 men and 16 women; age 35–72 years, mean 54 years) underwent the TIPS procedure. Techniques for portal vein localization before and during TIPS were fluoroscopy, computed tomography (CT) studies, wedged hepatic venography, arterial portography, and ultrasound. After predilation we deployed balloon-expandable (n=48) and self-expanding (n=45) metallic stents. Fifteen patients underwent variceal embolization. Initial follow-up angiograms (mean 6.9 months, range 3–24 months) were obtained in 39 of these patients. Results Fifty-three patients (93%) had successful TIPS placement. The mean decrease in portal pressure was 42.7%. Besides fluoroscopy, the most helpful techniques for portal vein localization were venography and CT. Residual stenosis (n=1) and late shortening (n=4) of Wallstents resulted in shunt dysfunction. The technical problems encountered with the Palmaz stent resulted from its lack of flexibility. We combined balloon-expandable and self-expanding stents in 12 patients. The 30-day and late follow-up (mean 11.9 months) percutaneous reintervention rates were 11.3% and 64.2%, respectively. There were no clinically significant complications related to the TIPS insertions. Conclusion An ideal stent does not exist for TIPS, and the authors recommend combining a Palmaz stent with a flexible self-expanding stent.     

Cardiovascular Laser Application

With the invention of the laser, many clinical disciplines have taken advantage of this new energy source. Its precision, intensity and energy density is superior to all other known surgical devices. Based on the principle of light amplification from a photon-emitting resonator, the monochromaticity, collimation and coherence provide the high-energy density of the laser beam for medical applications. The state-of-the-art and future potential of laser use in cardiovascular diseases will be reviewed. Most of the work in this field has been accomplished during the past decade with numerous research projects. Although many technical advances have been made, so far the results in cardiovascular medicine are in the areas of vessel anastomosis, ablation of conduction passes for arrhythmia therapy, and angioplasty. In this paper, special attention will be given to the recent success in XeCl excimer laser application for photodecomposition of tissue with a goal of improved recanalization. The high-power density of the XeCl excimer laser provides significant advantages for the disruption of both embolic and calcified plaque. Regardless of the type of tissue ablated, gross, histologic, and ultra-structural analysis confirmed the absence of thermal injury in luminar recanalization as well as in animal studies. Progress in the manufacture of catheters, with multiple very small diameter fibers, led to the decisive breakthrough in clinical laser angioplasty. Peripheral as well as coronary arteries have been successfully recanalized followed by balloon dilatation. The ease of application and the success achieved thus far have resulted in an optimistic assessment for laser medicine.     

A glutamatergic mechanism for aluminum toxicity in astrocytes

The effect of aluminum on the metabolism of glutamate and glutamine in astrocytes was studied to provide information about a possible biochemical mechanism for aluminum neurotoxicity and its potential contribution to neurodegenerative disease. Exposure of cultured rat brain astrocytes for 3–4 d to 5–7.5 mM aluminum lactate increased glutamine synthetase activity by 100–300% and diminished glutaminase activity by 50–85%. Increased glutamine synthetase enzyme activity was accompanied by an elevated level of glutamine synthetase mRNA. Alterations in glutaminase and glutamine synthetase following aluminum exposure caused increased intracellular glutamine levels, decreased intracellular glutamate levels, and increased conversion of glutamate to glutamine and the release of the latter into the extracellular space. The results of these changes may alter the availability of neurotransmitter glutamate in vivo and may be a mechanism for the aluminum neurotoxicity observed in individuals exposed to the metal during dialysis procedures and other situations.     

Concerning the differentiability of the energy function in vector quantization algorithms.

The adaptation rule of Vector Quantization algorithms, and consequently the convergence of the generated sequence, depends on the existence and properties of a function called the energy function, defined on a topological manifold. Our aim is to investigate the conditions of existence of such a function for a class of algorithms including the well-known 'K-means' and 'Self-Organizing Map' algorithms. The results presented here extend several previous studies and show that the energy function is not always a potential but at least the uniform limit of a series of potential functions which we call a pseudo-potential. It also shows that a large number of existing vector quantization algorithms developed by the Artificial Neural Networks community fall into this class. The framework we define opens the way to studying the convergence of all the corresponding adaptation rules at once, and a theorem gives promising insights in that direction.     

Tissu adipeux : glande endocrine polyvalente

Research on the adipose tissue secretions has undergone a major inflection for a few years. The investigators became aware that the biology of the various cells of the stroma-vascular fraction of adipose tissue was to be taken into account to include/understand the diversity of the secretions. The adipose tissue is a site of production of adipokines (strictly synthesized and secreted by the adipocyte), of pro- or anti-inflammatory cytokines and of acute phase reactant proteins. Cells of the stroma-vascular fraction (monocytes/macrophages, microvascular endothelial cells…) have a secretory importance neglected up to now. The action of both major adipokines (leptin and adiponectin) will be more particularly evoked while considering the diversity of action of the other most current factors. Finally some secreted products more recently discovered (apelin, autotaxin, visfatin.), whose properties are still in the course of exploration, will be also mentioned.     

Peripheral Blood Lymphocyte Surface Antigen Expression and Prognosis in Myeloma: Australian Leukaemia Study Group Study

The Australian Leukaemia Study Group myeloma study (MM1) aimed to determine the prognostic significance of clinical and immunophenotypic markers in patients with multiple myeloma. All patients were treated with standard dose melphalan and prednisone. Seventy-four patients were entered and the median survival was 27 months. Serum beta 2-microglobulin (βM) and albumin levels were the only significant clinical factors influencing survival (p = 0.007 and p = 0.008, respectively). Patients with raised levels of CD38+ lymphocytes at presentation had a significantly shorter survival than patients with normal levels (p = 0.01, logrank test, median 19 months vs 33 months). CD38 antigen expression was independent of β2M but patients with raised levels of CD38 had significantly lower levels of albumin than patients with normal levels (p = 0.001) which may explain their poorer survival. Salmon and Durie stage was not associated with antigen expression. No other B-cell antigens (CD10, CD19, CD20, CD21, CD22, CD23, FMC1 or FMC7) or plasma cell antigens tested (PCA-1) were found to be associated with prognosis. Patients who achieved plateau phase had a better prognosis than those who did not (p = 0.04 in a landmark analysis). Patients who achieved plateau phase following an objective response appeared to have a better prognosis than those who were in plateau phase at presentation (p = 0.09 in a landmark analysis). Light chain isotype suppression (LCIS) was not associated with a significant survival advantage and did not correlate with any known prognostic indicator. We conclude that phenotypic analysis of peripheral blood lymphocytes for CD38 antigen at diagnosis may be useful as a prognostic indicator in patients with myeloma.