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Biomedical subjects

M Alexandre

Publications and source records attributed to M Alexandre.

18 recordsLinked to original sources
PubMed2003

[Alveolar echinococcosis of the liver. Mass ultrasound screening in the Haut Cantal area].

OBJECTIVE: Mass systematic screening for alveolar echinococcosis (AE) of the liver in the Haut Cantal endemic area. MATERIAL AND METHODS: Targeted population was composed of the members of the Mutualité Sociale Agricole of the area, from 16 to 65 years old. 2077 notifications were sent, corresponding to 20% of the population of this area, defined by a triangle between Egliseneuve d'Entraigues, Riom ès Montagne and Saint Flour. Two screening tests were performed: Elisa serology test and liver ultrasound examination. RESULTS: Participation levels were relatively low-ultrasound: 18.92%, serology: 17%. Among 350 liver examinations, 2 suspicions of AE were found: CT and serology confirmed the diagnosis in the first symptomatic patient; CT and biopsy confirmed the diagnosis in the other asymptomatic patient in whom serology was normal. CONCLUSION: Ultrasound screening showed at least a 0.57% prevalence of AE, i.e., 2 cases out of 350. This low rate however confirms that Haut Cantal is an endemic area, but with a lower incidence rate than in other endemic areas.

Adolescent↗
PubMed2001

Mechanisms and kinetics of thermal degradation of poly(epsilon-caprolactone).

Thermogravimetric analysis (TGA) simultaneously coupled with mass spectrometry (MS) and Fourier transform infrared spectrometry (FTIR) was developed as an original technique to study the thermal modification/degradation of poly(epsilon-caprolactone) (PCL) through in depth analysis of the evolved gas. Perfectly well-defined PCL samples with controlled end groups, predictable molecular weight, and narrow molecular weight distribution were synthesized by living "coordination-insertion" ring-opening polymerization of epsilon-caprolactone initiated by aluminum triisopropoxide. TGA analyses carried out on purified PCL samples, deprived from any residual catalyst or monomer, highlighted a two-step thermal degradation. Evolved gas analysis by both MS and FTIR showed that the first process implies a statistical rupture of the polyester chains via ester pyrolysis reaction. The produced gases were identified as H(2)O, CO(2), and 5-hexenoic acid. The second step leads to the formation of epsilon-caprolactone (cyclic monomer) as result of an unzipping depolymerization process. The influence of parameters such as polyester molecular weight, nature of the PCL end groups, and presence of catalytic residues as well as the type of purge gas were investigated. The activation energy of the thermal degradation was also studied.

Chromatography, Gel↗
PubMed2001

Detection of enterohemorrhagic Escherichia coli in meat foods using DNA probes, enzyme-linked immunosorbent assay and polymerase chain reaction.

Enterohemorrhagic Escherichia coli (EHEC) is an important cause of diarrhoea with blood and haemolytic uremic syndrome (HUS) in children and elderly people. Infections with EHEC are a world-wide public health problem, related to consumption of contaminated ground beef. The aim of this study was to establish whether different meat foods sold in Santiago, Chile pose an infection risk by EHEC and to evaluate three different diagnostic techniques in foods, to determine which is most applicable for use in Chile. A parallel analysis was performed on 64 samples of meat foods (23 refrigerated ground meat, 23 refrigerated long pork sausages and 18 frozen hamburgers) sold in Santiago, Chile using DNA probes, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). Twenty-four samples (24 of 64 = 37.5%) were positive by DNA probes, ELISA or PCR. The positive and negative predictive values, sensitivity and specificity of ELISA were 26.7, 81.6, 30.8 and 78.4%, respectively. The positive and negative predictive values, sensitivity and specificity of PCR were 91.7, 96.2, 84.6 and 98%, respectively. The EHEC serogroups most frequently isolated were O158, O157, O119, O125 and O114. These results show that, although molecular techniques such as enzyme immunoassays are useful for EHEC detection in meat foods, PCR has advantages in terms of sensitivity, specificity, cost and ease of implementation in Chile.

Animals↗
PubMed2001

[Phage typing of Salmonella enteritidis isolated from clinical, food, and poultry samples in Chile].

Since 1994 an extensive epidemic of infections with Salmonella enteritidis (S. enteritidis) has affected Chile. In order to understand the diversity of infective sources, the possible origin of the epidemic, and the epidemiological relationships between clinical, food, and poultry isolates, we carried out phage typing of three groups of samples: 1) 310 S. enteritidis clinical samples collected between 1975 and 1996, 2) 47 food isolates obtained during S. enteritidis outbreaks, and 3) 27 strains isolated in surveillance studies of poultry-raising establishments. With the clinical samples, a total of 13 phage types were identified, 2 isolates could not be typed, and 1 was considered atypical. The phage types that were identified most frequently were 1 (56.8%) and 4 (31.3%), trailed by type 8 (4.8%) and type 28 (1.9%). Over time and in different regions of the country there were major changes in the distribution of the phage types. In the first years of collection the only phage types registered were 8 and 28, which disappeared around 1980 and then began reappearing sporadically in 1996. With the gradual S. enteritidis expansion that started in 1988, in the central and southern areas of the country phage type 4 began to appear; that type had not been found before in Chile. In 1991 in the northern area of the country phage type 1 began to predominate; it was another type that had not been reported before in Chile. In the food isolates the only phage types identified were 1 and 4, which were also the most common in the poultry isolates. Phage typing of S. enteritidis has proved to be useful in guiding the epidemiological analysis of the infections caused by this pathogen.

Animals↗
PubMed2000

Visualisation of the portal flows by porto-scanner.

This study presents a retrospective analysis of 15 portal vein CT scans, conducted for the evaluation of hepatic metastasis in patients suffering from colorectal cancer, with the aim of verifying in vivo the presence of laminar flow as reported by Pironcof. After selective catheterization of the superior mesenteric artery, CT scans were performed during opacification of the portal vein. Different flows were identified by the incomplete opacification they induced in the portal vein. Splenic flows could always be identified, however right colic and superior mesenteric flows were only seen in 3 cases (20%) and gastrocolic flow in 2 (13.6%). Even though incremental (i.e. slower than helical) the CT acquisitions allowed the flows to be viewed by modifying the visualisation window. In vivo evidence of laminar flow is provided which supports Pironcof's experimental observations.

Colorectal Neoplasms↗
PubMed2000

[Detection of Salmonella enteritidis in samples of poultry products for human consumption in the Chilean metropolitan area].

BACKGROUND: Salmonella enteritidis (SE) is a frequent cause of diarrhea, and is transmitted mainly by SE contaminated eggs or poultry meat. The frequency of SE contaminated eggs or chicken meat and the risk for acquiring this pathogen is unknown in Chile. AIM: To measure SE contamination in eggs poultry meat and entrails offered in retail markets in the Metropolitan Area during two consecutive years (1998-1999). MATERIAL AND METHODS: Samples were placed in sterile bags and transported to the laboratory before 4 hours at 4 degrees C. Microbiologic detection was done using a standard procedure and an immunodetection assay. RESULTS: SE was found in one of 1081 egg samples (0.09%). The contaminated sample was offered in a supermarket under their own commercial name. Six percent of 1154 poultry meat samples were contaminated by SE and 2.3% by other Salmonella serotypes. Entrails had even higher rates with 10.2% of 370 samples harboring SE and 2.7% other serotypes. Total Salmonella sp. isolates and SE isolates declined during 1999. Nine SE phagotypes were identified, predominating types 4 and 7. CONCLUSIONS: Eggs and other avian products are contaminated by different SE phagotypes and other Salmonella serotypes, implicating a risk for the consumers (Rev Méd Chile 2000; 128: 1075-83).

Animals↗
PubMed1999

Benign and malignant hepatocellular tumors: evaluation of tumoral enhancement after mangafodipir trisodium injection on MR imaging.

The aim of this work was to study the ability of mangafodipir trisodium (Mn-DPDP)-enhanced MR imaging in differentiating malignant from benign hepatocellular tumors. Eleven patients with pathologically proved hepatocellular carcinomas, six with focal nodular hyperplasias, and one with a single hepatocellular adenoma were examined by spin-echo and gradient-echo T1-weighted sequences before, 1 h after, and 24 h after intravenous injection of Mn-DPDP (5 micromol/kg). Quantitative analysis including enhancement and lesion-to-liver contrast-to-noise ratio, and qualitative analysis including the presence of a central area and a capsule were done on pre- and post-Mn-DPDP-enhanced images. Enhancement was observed in all the tumors with significant improvement (p < 0.05) in contrast-to-noise ratio 1 h after, and 24 h after intravenous injection of Mn-DPDP. There were no significant differences in the mean enhancement and the mean contrast-to-noise ratio (CNR) between benign and malignant tumors. No enhancement was seen within internal areas observed in 7 hepatocellular carcinomas, and in 5 focal nodular hyperplasias, and within capsules which were observed in 9 hepatocellular carcinomas. In our study, Mn-DPDP increased CNR of both benign and malignant tumors but did not enable differentiation between benign and malignant tumors of hepatocellular nature.

Adenoma, Liver Cell↗
PubMed1999

Clonal diversity of Chilean isolates of enterohemorrhagic Escherichia coli from patients with hemolytic-uremic syndrome, asymptomatic subjects, animal reservoirs, and food products.

To determine clonal relationship among Chilean enterohemorrhagic Escherichia coli (EHEC) strains from different sources (clinical infections, animal reservoirs, and food), 54 EHEC isolates (44 of E. coli O157, 5 of E. coli O111, and 5 of E. coli O26) were characterized for virulence genes by colony blot hybridization and by pulsed-field gel electrophoresis (PFGE). By colony blotting, 12 different genotypes were identified among the 44 E. coli O157 isolates analyzed, of which the genetic profile stx1+ stx2+ hly+ eae+ was the most prevalent. All human O157 strains that were associated with sporadic cases of hemolytic-uremic syndrome (HUS) carried both the stx1 and stx2 toxin-encoding genes and were eaeA positive. Only 9 of 13 isolates from human controls were stx1+ stx2+, and 8 carried the eaeA gene. Comparison of profiles obtained by PFGE of XbaI-digested genomic DNA showed a great diversity among the E. coli O157 isolates, with 37 different profiles among 39 isolates analyzed. Cluster analysis of PFGE profiles showed a wide distribution of clinical isolates obtained from HUS cases and asymptomatic individuals and a clonal relationship among O157 isolates obtained from HUS cases and pigs. Analysis of virulence genes showed that a correlation exists among strains with the genotype stx1+ stx2+ eae+ and pathogenic potential. A larger difference in the PFGE restriction patterns was observed among the EHEC strains of serogroups O26 and O111. These results indicate that several different EHEC clones circulate in Chile and suggest that pigs are an important animal reservoir for human infections by EHEC. Guidelines have been proposed for better practices in the slaughter of animals in Chile.

Animals↗
PubMed1999

[Hepatocellular carcinoma in cirrhosis: semeiology and performance of magnetic resonance imaging and lipiodol computed tomography].

OBJECTIVES: a) Describe hepatocellular semiology in magnetic resonance imaging and lipiodol computerized tomography in patients with cirrhosis, who are candidates for surgery; b) Clarify the respective roles of magnetic resonance imaging and lipiodol computerized tomography in hepatocellular detection. METHODS: Twenty four patients with suspected hepatocellular carcinoma underwent successive magnetic resonance imaging and lipiodol computerized tomography. Thirty-four of the 67 lesions seen by lipiodol computerized tomography and 28 of 52 lesions seen by magnetic resonance imaging were confirmed histologically. RESULTS: In lipiodol computerized tomography, 44% of hepatocellular carcinomas had a dense and homogeneous pattern; 24% had a homogeneous but slightly dense pattern. Sixteen distinct deposits were described: 4 were confirmed as hepatocellular carcinoma and 12 were not controlled histologically. In magnetic resonance imaging 57% of hepatocellular carcinomas have a high intensity on T1 and T2 weighted spin echo images, 38% were hyperintense on T2 and hypo or isointense on T1 weighted images. Eighty-six percent of hyperintense T1 and T2 weighted images were hepatocellular carcinoma. When the gold standard was histology, lipiodol computerized tomography sensitivity (81%) was higher than magnetic resonance imaging (68%). When the gold standard was lipiodol computerized tomography, the sensitivity of magnetic resonance imaging was 47 +/- 12%. CONCLUSIONS: a) The sensitivity of lipiodol computerized tomography was better than resonance magnetic imaging; b) the homogeneous and slightly dense pattern corresponded to a hepatocellular carcinoma in 50% of cases; c) on magnetic resonance imaging any lesions with high intensity on T1 and T2 spin echo images strongly suggests hepatocellular carcinoma; d) if surgical resection after ultrasonography is being considered, the second step should be an magnetic resonance imaging.

Aged↗
PubMed1998

[Does neoadjuvant radiochemotherapy augment the resectability of pancreatic cancers?].

PURPOSE OF THE STUDY: Pre-operative radiochemotherapy is the most recent therapeutic option in the pre-operative downstaging of pancreatic cancer and in decreasing the rate of positive resection margins. The purpose of the study was to evaluate tolerance and efficacy of pre-operative radiochemotherapy in unresectable pancreatic cancers. MATERIAL AND METHODS: This study included seven cases of pancreatic cancer considered unresectable. The patients received preoperatively 50 grays within a 5-week period associated with 5 FU and Platin during the 1st and 5th weeks. RESULTS: After radiochemotherapy, tomodensitometric evaluation showed a minor response in two cases. A pancreatico-duodenectomy could be performed in these two patients without any increase of pre- or post-operative morbidity or mortality. CONCLUSIONS: The results of the study suggest that preoperative radiochemotherapy may increase pancreatic cancer resectability. This hypothesis should be confirmed by a prospective randomised trial.

Adenocarcinoma↗
PubMed1997

[Progressive lenses, history and comfort factors].

Since some fifteen years, progressive glasses tend to replace gradually the bifocal ones as first choice of the correction of presbyopia. This tendency varies however according to continents and countries. The idea of the progressive glass returns mainly to a French (Maitenaz) working in 1956 for the firm Essilor. At that time, large reticences had been emitted by the other firms manufacturing glasses, that do not suspect the success that would have later this kind of correction once imperfections of the infancy will have been solved. Progressive glasses have been improved by taking account of remarks of wearers and by privileging the comfort in the current life, ending to glasses well supported by most of the presbyopes.

Equipment Design↗
PubMed1995

[Actinomycosis: value of percutaneous drainage of intra-abdominal abscesses].

Abdominal actinomycosis was localized in the liver with intra-abdominal abscesses. The disease had evolved for several years before diagnosis. Percutaneous interventional radiology allowed taking biopsies which confirmed the diagnosis. Percutaneous drainage of the intra-abdominal abscesses with antibiotherapy was successful without iterative surgery.

Abdominal Abscess↗
PubMed1993

[Pattern of blood creatinine levels in 140 hypertensive patients after successful percutaneous transluminal angioplasty for renal artery stenosis].

Long term effects on creatinine serum level of successful percutaneous transluminal renal angioplasty were retrospectively studied in 140 patients. 3 groups were distinguished: the first one (80 patients) included unilateral renal angioplasties, with normal contralateral kidney and renal artery; the second group (35 patients) included bilateral renal angioplasties; the third group (25 patients) included solitary kidney renal artery angioplasties. In each group, subgroups were defined whether creatinine serum level was upper or lower than 130 mumol/l. Renal function was considered to be improved if serum creatinine was reduced by 20% or more, maintained if serum creatinine variations were below 20%, worsened if its increase was upper than 20%. Global complication rate was 4.9% (9 between 185 patients) of whom 1 (0.54%) needed a surgical revascularization. At the end of follow-up (mean between 4 and 10 months), subgroups improvement and stabilization rates varied between 67 and 100%, with the best scores in the second group (96.2 and 100%) and solitary kidney with renal insufficiency subgroup (77.25%).

Angioplasty, Balloon↗
PubMedDate not supplied

Percutaneous recanalization of recent renal artery occlusions: report of 10 cases.

PURPOSE: Percutaneous recanalization of renal artery occlusion was attempted in 10 patients. METHODS: All patients were hypertensive; before the procedure, the serum creatinine level was 80 mumol/L in one patient, ranged from 130-250 mumol/L in four patients, and was greater than 350 mumol/L in five, three of whom had anuria. Nine occlusions were thrombotic, one due to bilateral renal artery embolism. In four patients, percutaneous transluminal angioplasty of a contralateral renal artery occlusion was bilateral. In three patients, complementary local fibrinolysis was necessary. RESULTS: Three technical failures and one rethrombosis occurred after 24 h; in three of these cases the date of previous occlusion was unknown, whereas a relatively precise data was known for the seven other patients. One false aneurysm of the femoral artery was found 1 month after the procedure. One patient, after six technical successes, died 5 weeks after the procedure; follow-up for the other five was 6-36 months. Blood pressure was unchanged in four patients and improved in two. A significant and durable improvement of creatinine serum level (at least a 20% decrease) was observed in all six patients, usually after 1 month, thus enabling discontinuance of dialysis in three patients. CONCLUSION: Percutaneous recanalization should be proposed in cases of renal artery occlusion, especially to avoid terminal vascular azotemia and dialysis.

Adult↗
PubMedDate not supplied

Local fibrinolysis for superior mesenteric artery thromboembolism.

A 66-year-old man with atrial fibrillation was referred soon after developing left lower limb and abdominal pain with rectal bleeding. An immediate flush aortogram showed embolic occlusion of the left distal superficial femoral artery and superior mesenteric artery (SMA), 3 cm from its ostium. Recombinant tissue plasminogen activator (rtPA) 40 mg was selectively instilled in the SMA in two boluses. Abdominal symptoms resolved within 48 h, and complete recanalization of the SMA was shown on angiography. Exploratory laparotomy after 72 h showed a normal small bowel and right colon, and was completed by femoropopliteal embolectomy. Six months later, the patient remained asymptomatic.

Aged↗