Phospholipids inTrypanosoma cruzi: Phosphoinositide composition and turnover

The polyphosphoinositides fromTrypanosoma cruzi were isolated by preparative thin-layer chromatography (TLC) and identified. When myo-[³H]inositol was present in the culture medium for five days, analyses showed the presence of phosphatidylinositol (PI), lysophosphatidylinositol (lysoPI), phosphatidylinositol 4-phosphate (PIP) and phosphatidylinositol 4,5-bisphosphate (PIP₂). Short-term incubation with³²P_i led to higher percentages of incorporation into phosphatidylethanolamine (PE), lysophosphatidylethanolamine (lysoPE) and PI compared to the other glycerophospholipids. The phosphoinositides (PI, PIP and PIP₂) contained a larger proportion of unsaturated than saturated fatty acids. High proportions of 18∶2 were found in the three phosphoinositides analyzed, whereas the major saturated fatty acid was 18∶0. Watersoluble inositol phosphates (IP, IP₂ and IP₃) were also identified.     

Effect of oxidative stress, produced by cumene hydroperoxide, on the various steps of protein synthesis. Modifications of elongation factor-2

We have studied the effect of oxidative stress on protein synthesis in rat liver. Cumene hydroperoxide (CH) was used as an oxidant agent. The approach used was to determine the ribosomal state of aggregation and the time for assembly and release of polypeptide chains in the process of protein synthesis in rat liver in vivo. The results suggest that the elongation step is the most sensitive to CH treatment. The measurement of both carbonyl groups content and ADP-ribosylatable elongation factor 2 (EF-2), the main protein involved in the elongation step, indicates that under CH treatment EF-2 is oxidatively modified and a lower amount of active EF-2 is present. These results are corroborated by in vitro oxidation of EF-2 and could explain for the decline in the elongation step.     

Surgical treatment of cicatricial biliary strictures

BACKGROUND/AIMS: Cicatricial biliary strictures are usually associated with high morbidity and mortality rates, frequently related to technical difficulties of their surgical repair, mainly in hilar lesions. Interference with bile duct blood supply during surgical attempts for correction is a major factor for unsuccessful results. The aim of this study is to evaluate, after an extended follow-up period, the results obtained with a modified technique for surgical correction of cicatricial biliary strictures. METHODOLOGY: The medical records of 57 patients surgically treated for cicatricial biliary strictures between January 1984 and July 1995 were reviewed and the immediate and long term results retrospectively analyzed. Patients consisted of 46 females and 11 males. The average age was 43 years. The etiology of the biliary lesion was: cholecystectomy alone (23); cholecystectomy with duct exploration (8); T tube CBD drainage (6); Biliary-enteric anastomosis stricture (16); choledochoplasty (2) and trauma (2). In 28 cases (49.1%) the stricture was located in the upper third of the bile duct, in 28 (49.1%) in the middle third and in one case (1.7%) it was low. All patients were submitted to longitudinal Roux-en-Y hepaticojejunostomy with mucosa apposition after dissection of the anterior aspect of the biliary tract. No transanastomotic stents were used. RESULTS: Ten patients (17.5%) presented 11 postoperative complications: biliary fistula (4), duodenal fistula (1), wound infection (5), and acute pancreatitis (1). Average hospital stay was 11 days and there were no postoperative mortalities. The follow-up study was possible in 54 patients and ranged from one to ten years, with an average of 2.9 years. Four patients of 28 (14%) with hilar lesions developed stricture recurrence and cholangitis episodes, whereas no patients bearing lesions below the biliary junction had such complications. CONCLUSION: Roux-en-Y hepaticojejunostomy with mucosa apposition without transanastomotic stent performed after minimal dissection of the biliary duct, thus avoiding major interference with the bile duct blood supply, is a safe and efficient method for the surgical repair of cicatricial biliary strictures. Using this technique excellent results can be obtained in the lesions below the biliary junction and acceptable results may be achieved in patients with hilar lesions.     

Renovascular arterial hypertension. Importance of subtraction digital angiography in its diagnosis

The objective of this study is to contribute to the positioning of the intravenous digital subtraction angiography (IVDSA) in the detection of morphologic abnormalities of renal arteries (RAs), susceptible to originate renovascular hypertension (RVH). The authors focus on the prevalence of RVH in the broad spectrum of systemic arterial hypertension. The definition of RVH is given and its diagnostic criteria are revisited. The angiography methods used in the evaluation of RAs morphologic abnormalities are described.     

Renovascular arterial hypertension. From physiopathology to therapy

Understanding the pathophysiology, diagnosis, and management of renovascular hypertension (RVH) is of paramount importance due to the severity of hypertension (HT) and renal insufficiency (RI). Moreover, adequate treatment by surgery and/or endovascular intervention can improve HT and revert RI. The comprehension of the pathophysiology of RVH had its origin on the experiments of Goldblatt which led to the recognition of the renin dependent, volume dependent, and mixed types. A continuum seems to exist, from an acute phase, supported by the endocrine renin angiotensin aldosterone system, evolving towards a chronic phase sustained by the local renin angiotensin system. The involved vasoconstrictor and mitogenic mechanisms may contribute to the arterial remodeling. The most common forms of pathology, i.e. atherosclerosis, fibromuscular dysplasia (FD), and Takayasu's arteritis, and their natural history, are described. The prevalence of RVH, ranging from 0.2% to more than 25%, depending on the clinical situation, is evidenced. Clinical symptoms and signs and the most important diagnostic tests are pointed out: functional tests (captopril test, postcaptopril renography, scintigraphy, and renin determinations) and anatomical tests (intravenous digital angiography and intrarterial angiography). New imaging techniques are also referred. A diagnostic work-up based on the index of clinical suspicion is described. The therapeutic goal is the resolution of the two main problems of RVH: hypertension and ischemic nephropathy. Revascularization is becoming mandatory either by percutaneous transluminal angioplasty mostly for FD and atheromatous non-ostial stenoses, or by surgery, which is preferred for patients with ostial or peripheral stenoses, aneuryms, occlusions and concomitant aortic disease. A better knowledge of RVH allows, not only diagnosis and treatment of one of the most frequent types of secondary hypertension, but also the control of the resulting ischemic nephropathy.     

Masse du fluide frigorigène dans un évaporateur en fonctionnement permanent ou transitoire: Refrigerant mass inside an evaporator in a steady or non-steady state

The present study was undertaken to achieve an experimental determination of the refrigerant mass inside an evaporator of a refrigerating machine operating under steady or non-steady conditions. The mass was measured during the steady regime over a wide range of operating conditions and the mass variations were evaluated during steps of the expansion valve. From the results of the laboratory experiments, a correlation of the refrigerant mass variation is proposed, taking into account the compressor variable-speed and the vaporization temperature. An analysis of the results is presented and a theoretical method for predicting the refrigerant mass in the evaporator is proposed.     

Depletion of radiosensitive leukocytes exacerbates the heart sympathetic denervation and parasitism in experimental Chagas'' disease in rats

We presently examine the relation between histologic infarct size and neurologic deficit as endpoints and seek to clarify their sensitivity in defining stroke outcome. Neurologic deficits of 76 cats subjected to middle cerebral artery occlusion were assessed daily and correlated with the corresponding infarct sizes determined morphometrically after 2 weeks' survival. A five-item neurologic deficit score included the time elapsed until hemiparesis, and forced circling resolved (if ever), presence of impaired placing reactions and time elapsed until able to stand and being alert. We then evaluated the two endpoints' statistical powers to detect group differences using two sets of comparison groups. The neurologic deficit score correlated well with infarct size (r = 0.76, p < 0.001) and each of the individual deficit score components named above, in turn, correlated with decreasing power with infarct size. Even so, the number of study subjects required to achieve the same level of statistical significance in assessing group differences was two-fold greater when using the neurologic deficit than the infarct size data: Group sizes of eight and five animals were sufficient for significant infarct size differences while the groups needed be expanded to 15 and 10 animals to similarly achieve significant neurologic score differences. Thus, infarct size emerges as a more sensitive measure of stroke outcome than does the assessment of neurologic deficits.     

Dendritic cells express multiple chemokine receptors used as coreceptors for HIV entry

Cells of the dendritic lineage are thought to be among the first cells infected after mucosal exposure to HIV. In this study, we have identified the presence of multiple chemokine receptors on dendritic cells (DC) that may function as coreceptors for HIV entry. DC effectively used CCR5 for entry of macrophage (M)-tropic isolates. CCR3, the eotaxin receptor, initially identified on eosinophils, is expressed on DC and may be used as an entry coreceptor by certain dual-tropic strains. CXCR4 was not expressed on DC, although SDF-1 induced a calcium flux and DC could be infected by T cell line (T)-tropic HIV. Our findings provide evidence for the presence of a non-CXCR4 SDF-1 receptor on DC that is used mainly by T-tropic strains of HIV. DC from individuals homozygous for a 32-bp deletion of the CCR5 gene are also infectable with M-tropic strains of HIV-1, and this infection is inhibited by stromal cell-derived factor (SDF)1, suggesting that this receptor can also be used by M-tropic HIV for entry. Delineation of the spectrum of coreceptor usage on DC may offer new approaches to interfere with the initiation and propagation of HIV infection.     

Simulating the displacement of a heavy oil by a lighter oil in an offshore production line

An analysis was conducted on the displacement of a heavy fluid by a miscible light fluid in the flow assurance operation of injecting diesel oil to displace heavy oil in an insulated offshore production line. A three-dimensional computational fluid dynamics model was developed and implemented in OpenFOAM®. It stimulates the production stages, no-touch time, and oil displacement, considering heat transfer through natural convection and conjugated heat transfer through the solid layers of the pipeline. The specific test case focused on the first 180 m of an existing offshore production line. The simulations revealed two primary mechanisms of mixing: turbulence and secondary flows generated by the pipeline curves. Remarkably, the results demonstrate that by injecting a volume of lighter oil 1.3 times the pipeline volume, approximately 90%–95% of the heavy oil can be effectively removed.     

Evacuation Processes Versus Evacuation Models: “Quo Vadimus”?

This paper promotes a discussion about evacuation models and their relation with evacuation processes. For this reason, the question “quo vadimus” (i.e., from Latin: where are we going to?) intends to initiate this discussion. Therefore, a brief overview of the importance of the evacuation modelling analysis within the Fire Safety Engineering (FSE) context is presented. This paper also presents an analysis of the evacuation modelling process and some remarks on how the evacuation models' reviews are being done as well. Furthermore, along with the previous question, some other subsequent key-questions can be aroused and this paper intends to analyse them, namely: Do we need the evacuation models for understanding evacuation processes? Are we doing the evacuation models' reviews properly? Do we understand well the evacuation models? Do we understand the evacuation modelling process?