Role of zinc and niobium in the giant piezoelectric response of PbZn(1/3)Nb(2/3)O(3).

Relaxor ferroelectric perovskites are highly polarizable and can exhibit giant coupling between elastic strain and an applied electric field. Here, we report an in situ extended X-ray absorption fine structure (EXAFS) study of a PbZn1/3Nb2/3O3 (PZN) single crystal as a function of the electric field. We show that the strong dipoles in the NbO6 octahedra bonds are aligned along the four ⟨011⟩ directions close to the orientation of the electric field, while a small reversible polar shift occurs for Zn in the direction of the electric field, i.e., positive or negative. This reversible Zn-O polar shift is proposed to play an important role in both the "easy" switching of the ferroelectric polarization and the giant piezoelectric effect in PZN.

[An unusual mode of snake poisoning in Tunisia]. / Un mode insolite d'envenimation vipérine en Tunisie.

Snake poisoning constitutes a real public health problem in the North African countries. In Tunisia, snake poisonings are particularly frequent in the sub-Saharan regions (southern areas) with high mortality and possible debilitation in survivors. The most common mode of snake poisoning is biting, particularly on the extremities. The purpose of this report is to describe a case involving a patient who presented authentic systemic signs of a snake poisoning after ingesting a whole raw viper of the Cerastes cerastes species. Local signs as well as coagulation abnormalities often associated with bites by this kind of viper were not observed. The outcome was favorable after three days of hospitalization. Treatment consisted of symptomatic measures and administration of antivenom therapy.

[Acute renal failure and rhabdomyolysis secondary to prolonged hunger strike. A case report]. / Grève de la faim prolongée compliquée d'une rhabdomyolyse et d'une insuffisance rénale aiguë. A propos d'un cas.

Acute renal failure following hunger strike has been rarely reported. We report a 47-year-old man, prisoner, who developed an acute renal failure secondary to hypovolemia and major rhabdomyolysis. Failure of hydration with persistence of oliguria and secondary pulmonary edema required hemodialysis with eventually a favorable outcome.

Safety and efficacy of colistin compared with imipenem in the treatment of ventilator-associated pneumonia: a matched case-control study.

OBJECTIVE: Our study aimed to determine the efficacy and safety of colistin in the treatment of ventilator-associated pneumonia (VAP) caused by pan-drug-resistant Pseudomonas aeruginosa or Acinetobacter baumanii. DESIGN: Pairwise, retrospective exposed-unexposed study. SETTING: Combined medical and surgical intensive care unit of Habib Bourguiba University Hospital (Sfax, Tunisia). PATIENTS: Sixty patients with VAP caused by pan-drug-resistant A. baumanii or P. aeruginosa matched to 60 controls with VAP caused by A. baumanii or P. aeruginosa susceptible to imipenem. All patients had normal renal function at the onset of antibiotic therapy. INTERVENTIONS: Case patients were treated by colistin intravenously and control patients were treated by imipenem intravenously. MEASUREMENTS AND RESULTS: Baseline characteristics were similar between the colistin and imipenem groups. The mean duration of antibiotic therapy for VAP was 9.5+/-3.8 days (range 5-22 days) with colistin and 8.9+/-2.8 days (range 5-20 days) with imipenem (p=0.32). A favorable clinical response to antibiotic therapy for VAP occurred in 45 patients (75%) in the colistin group and in 43 patients (71.7%) in the imipenem group (p=0.68). The time to resolution of infectious parameters after the initiation of antibiotic therapy was not statistically different between the two groups. During the antibiotic course, none of the patients in either group developed renal failure. CONCLUSIONS: We conclude that colistin can be a safe and effective option in the treatments of VAP caused by pan-drug-resistant P. aeruginosa or A. baumanii.

[Thrombotic microangiopathies. Incidence, pathogenesis, diagnosis, treatment and prognosis]. / Les microangiopathies thrombotiques. Incidence, physiopathologie, tableau clinique, prise en charge thérapeutique et pronostic.

INTRODUCTION: The objective of this work was to review current data about the pathophysiology, clinical features, and treatment of thrombotic microangiopathies. CURRENT KNOWLEDGE: Thrombotic microangiopathies are microvascular occlusive disorders characterized by systemic or intrarenal aggregation of platelets, thrombocytopenia, and mechanical injury to erythrocytes. In thrombotic thrombocytopenic purpura, systemic microvascular aggregation of platelets causes ischemia in the brain and other organs. In the hemolytic-uremic syndrome, platelet-fibrin thrombi occlude predominantly the renal circulation. Thrombotic microangiopathy is a rare disorder whose varied clinical manifestations result from the formation of platelet-rich thrombi within the microvasculature and consequent tissue ischemia. The clinical features are acute renal failure, microangiopathic hemolytic anemia and thrombocytopenia. This diagnosis is of considerable importance because of the possible fulminant clinical course. Some atypical forms may be unrecognized. Plasma exchange is the current reference treatment of thrombotic thrombocytopenic purpura. However, in the light of recent publications, either infusions of concentrates of purified enzyme or more intensive immunosuppressive therapy would be more specific.

[Prognostic factors of pneumococcal meningitis. Retrospective study of 31 cases]. / Facteurs de pronostic des méningites à pneumocoque. Etude rétrospective de 31 cas.

AIM: Our aim was to study the susceptibility of Streptococcus pneumoniae to antibiotics in patients with pneumococcal meningitis and to search for the prognosis factors in those patients. METHODS: We have studied retrospectively 31 cases of pneumococcal meningitis. Comparaisons were performed with univariate analysis. RESULTS: The mean age was 36.7 +/- 20.5 years (ranged: 9 and 78 years). The sex ratio was 3,4. The susceptibility of Streptococcus pneumoniae to penicillin G was affected in 10 cases (33% of isolated pneumococcus. The MIC to penicillin G was > or =2 in only one case. The hospital mortality was 26% (8/31). With univariate analysis, factors associated with death were: age > or =55 years (Ss p= 0,006, OR: 17.2 IC95%: 2.3-134), albuminorachie > or = 7 g/l (p = 0.002, OR: 22; IC95%: 1.9-2.51), shock (p = 0.031, OR: 6.7; IC95%: 1.05-42) and Glasgow Coma Score (GCS) < or =8 (p = 0.001, OR: 20; IC95%: 2.68-149). CONCLUSION: No susceptibility to penicillin G is not associated with a worse outcome in patients with pneumococcal meningitis. An age > or =55 years, albuminorachie > or =7 g/l shock and Glasgow Coma Score < or =8 at admission were determinant of the prognosis in our study.

[Traumatic unilateral renal artery thrombosis and protein C deficiency. A case report]. / Thrombose post-traumatique de l'artère rénale et déficit en protéine C. A propos d'un cas.

Post traumatic renal artery thrombosis is rarely described in the literature. This pathology can result from stretch injury to inelastic intima of the renal artery, or by the direct flow to the abdomen causing compression injury to the renal artery against the vertebral column. However, the association of this pathology with hematologic diseases (in particular protein C deficit) was never described. We report an observation of a 28-year-old man with an uneventful history who was admitted to the intensive care unit for traumatic head injury associated with post traumatic renal artery thrombosis requiring nephrectomy. The etiologic investigation of this thrombo-embolic complication reveals a protein C deficit. Our patient was improved under treatment. This original observation confirms that post traumatic renal artery thrombosis can be associated with hematologic diseases (in particular protein C deficit).

[Acute fatty liver of pregnancy. About 22 cases]. / Stéatose hépatique aiguë gravidique. A propos de 22 cas.

OBJECTIVE: To report the clinical experience, biochemical findings, complications and maternal outcome in patients with acute fatty liver of pregnancy (AFLP). PATIENTS AND METHODS: Retrospective study over a period of 11 years (1993-2003). The diagnosis of AFLP was confirmed by liver biopsy in 15 women. However, in 7 women a medical committee that took into account clinical symptoms, and laboratory findings assessed the diagnosis. RESULTS: Were included in this study, 22 women with a mean age of 30+/-5.4 years. Only 22.7% of cases were primigravid. The mean gestational age was 36+/-2.76 weeks (range 31-41 weeks). The fetus was a male infant in 75% of cases. Ten women were admitted in the hospital without jaundice. However 15 women had developed an icterus since their hospital admission or during ICU stay. The mean SAPS II on the ICU admission was of 24.86+/-11.2 points. Biological disturbances observed were mainly: liver cytolysis in 91% of cases, a trend to hypoglycaemia in 86%, a hypoprotidemia in 66.7% and CIVD in 32%. During their ICU stay, 19 women (86.4%) developed one or several organ failures associated to the hepatic failure and 18 women required blood transfusion. After an average stay of 7.5 days, evolution was marked by the death of seven patients (31.8%). Factors correlated with a poor prognosis were: the delay of medical consultation, the development of jaundice, the development of encephalopathy, respiratory or a circulatory failure. DISCUSSION AND CONCLUSION: AFLP is a rare but life-threatening complication. Furthermore AFLP shares features with other more common and less perilous illnesses. An early diagnosis and appropriate therapy of this pathology should improve the poor prognosis in our country.

[Thrombotic microangiopathies in the intensive care unit]. / Les microangiopathies thrombotiques en réanimation.

OBJECTIVES: To analyze the clinico-biological manifestations, identify the causes and evaluate the outcome of patients with severe thrombotic microangiopathies admitted in a Tunisian intensive care unit. METHODS: Retrospective study over a period of 10 years (1995-2004) in an intensive care unit. RESULTS: Were included in this study 9 cases with a mean age of 29.2+/-9 years (range 15-44 years). Fever was observed in 5 patients, neurological impairment in 5 and digestive manifestations in 6. Haemolytic anaemia, thrombocytopenia and acute renal failure were observed in 100% of the cases. In our study, the aetiologies of thrombotic microangiopathies were: complicated pregnancy in 6 cases, systemic lupus erythematosus in 1 case. In contrast, no aetiology was found in 2 patients. Plasma exchange was performed in 5 patients, while 4 patients received only plasma infusion. After an average stay of 18+/-12.5 days, evolution was marked by the death 3 patients. CONCLUSION: The incidence of severe thrombotic microangiopathies is rare in Tunisian ICU. The clinical manifestations are not specific. Despite the improvement in the outcome by exogenous plasma supply, thrombotic microangiopathies with severe organ dysfunctions leading to hospitalization in the intensive care unit are associated with a high mortality rate.

Prevalence of hospital-acquired infection in a Tunisian hospital.

In order to estimate the prevalence of hospital-acquired infection (HAI) and research factors associated with its occurrence, a one-day prevalence survey was conducted at the Habib Bourguiba University Hospital, Tunisia. We studied 280 patients who had been present in the same ward for at least 48 h, and who had occupied a hospital bed between 17 April 2002 (midnight) and 18 April 2002 (midnight). The overall prevalence of HAI was 17.9%. The most frequently infected sites were the lungs (32%), surgical wounds (28%) and the urinary tract (20%). Microbiological documentation was available in only 28% of HAIs, and the most frequently isolated organisms were Gram-negative rods (80.8%). Results of multiple logistic regression analysis indicated that HAI is linked to the medical category, the use of intravascular devices and antibiotic prophylaxis. This survey provided information on the prevalence of HAI in Tunisian hospitals, the breakdown of infections, and HAI predisposing factors.

[Predictive value of pericatheter skin cultures in detecting catheter-related infections in a medical-surgical intensive care unit]. / Apport diagnostique de l'écouvillonnage de la zone d'insertion cutanée dans l'exploration des infections liées aux cathéters veineux centraux dans un service de réanimation médicochirurgicale.

OBJECTIVE: To evaluate the predictive value of pericatheter skin cultures in detecting catheter-related infections in critically-ill patients. STUDY DESIGN: Prospective study. PATIENTS AND METHODS: Over a 5 months period (from August 1(st) 2001 to December 31 2001), 500 patients were hospitalised, and 108 central venous catheters were prospectively examined. For each catheter, blood cultures, pericatheter skin cultures and semiquantitative culture of the catheter tip were performed. RESULTS: The median duration of catheterization was 8 days (interquartile: 8 days). Catheter was removed because of suspected infection in 54 cases (50%). Systemic catheter-related infection was found in 12 cases (11%) and the responsible organism was a gram-negative rod in 11 cases (92%). The negative predictive values of pericatheter skin cultures in the diagnosis of catheter-related infections and in case of suspected catheter-related infection were 89 and 86%, respectively. CONCLUSION: These results indicate that the pericatheter skin cultures are not an effective procedure for the conservative diagnosis of catheter-related infections and that the skin-insertion wound is not the major source of catheter-contamination in our unit.

[Cardiogenic pulmonary edema following ß2 agonist infusion for acute, severe asthma]. / Œdème aigu du poumon secondaire à l'administration intraveineuse de ß2 mimétiques pour asthme aigu grave.

We report the case of a severe acute pulmonary edema secondary to the administration of salbutamol to a patient admitted for severe asthma. The diagnosis of acute pulmonary edema was suspected on the clinical examination, chest radiography, biological (plasmatic Pro-BNP rate) and echocardiographic findings. Rapid improvement under dobutamine and mechanical ventilation argue in favour of cardiogenic pulmonary edema. The young age of our patient, the absence of history of cardiovascular disease and the chronology of this complication onset regarded to salbutamol infusion could suggest ß2 agonist involvement in this event. The improvement of cardiac function on echocardiography and the normal results obtained with myocardial perfusion scintigraphy performed 35 days later show the left ventricular reversible dysfunction.

[Pregnancy-induced hypertension complicated by acute pancreatitis]. / Pancréatite aiguë nécrotico-hémorragique secondaire à une hypertension artérielle gravidique.

The acute pancreatitis is a rare complication during the pregnancy. Causes are dominated by the gallstones and hyperlipidemia. This case report describes a 35-year-old pregnant woman who developed acute pancreatitis while suffering from a severe pre-eclampsia syndrome. Since she had no gallstones or other known aetiological factors of acute pancreatitis, the possibility of an etiologic role of pancreatic ischaemic changes associated with eclampsia is discussed. Evolution was marked with multi-organ system failure and poor outcome. Our experience and the previously reported case suggest that pre-eclampsia could be added to the list of causes of the acute pancreatitis.

[Drug's administration via feeding tubes: evaluation of practices in an intensive care unit of a Tunisian hospital]. / Administration des médicaments par sonde de nutrition entérale : évaluation des pratiques dans un service de réanimation médicale d'un hôpital tunisien.

INTRODUCTION: Drugs' administration via feeding tubes is a potential source of iatrogenic events for the intensive care patients because of the problem of not adapted galenic forms. OBJECTIVES: We analyzed the prescriptions of patients with enteral feedings to determine if the galenic forms were compatible with administration via feeding tubes. We also observed and analyzed the methods of drugs passage by nurses. PATIENTS AND METHODS: We analyzed 30 prescriptions of patients with enteral feedings in the intensive care unit of Habib Bourguiba Sfax hospital, by a prospective and exhaustive way. We also, observed and evaluated the practices of preparation and administration of drugs to these patients via feeding tube by nurses. RESULTS: Only 12% of drugs were liquids. Eighty-eight percent of the drugs were pulverised and capsule open before administration. The galenic form was not in conformity for 20% of drugs because of the prohibition to crushing tablet or opening capsule (gastroresistant form was dissolved), or because of the administration of a parenteral form (risk of irritation). Among 78 drugs administered by 10 different nurses, the time between passage of the drug and enteral nutrition were not respected for 59% of the observations. The drugs were managed in mixture for 90% of the observations. The gloves were not worn in 80% of observations. No rinsing is made between consecutive administrations and before administration. CONCLUSION: This study shows that it is possible to reduce risk of administration errors in the intensive care unit and to facilitate the administration of drug via feeding tube by prescribing liquid oral form or soluble solid oral form. It also shows the need for cooperation with the pharmacist in order to adapt the galenic forms and to redact protocol of administration.

[Peripartum cardiomyopathy: incidence, pathogenesis, diagnosis, treatment and prognosis]. / Myocardiopathie du péripartum : incidence, physiopathologie, manifestations cliniques, prise en charge thérapeutique et pronostic.

INTRODUCTION: Peripartum cardiomyopathy (PPCM) is a rare and life-threatening disease of unknown aetiology. The primary objective of this review was to analysed aetiopathogeneses, clinical presentation and diagnosis, as well as pharmacological, perioperative and intensive care management and prognosis of this pathology. METHODS: We undertook a systematic review of the literature using Medline, Google Scholar and PubMed searches. RESULTS: Unlike other parts of the world in which cardiomyopathy are rare, dilated cardiomyopathy is a major cause of heart failure throughout Africa. Its aetiopathogenesis is still poorly understood, but recent evidence supports inflammation, viral infection and autoimmunity as the leading causative hypotheses. This diagnosis should be limited to previously healthy women who present with congestive heart failure (CHF) and decreased left ventricular systolic function in the last month of pregnancy or within 5 months after delivery. Recently, introduction of echocardiography has made diagnosis of PPCM easier and more accurate. Conventional treatment consists of diuretics, vasodilators, and sometimes digoxin and anticoagulants, usually in combination. Patients who fail to recover may require inotropic therapy. In resistant cases, newer therapeutic modalities such as immunomodulation, immunoglobulin and immunosuppression may be considered. Prognosis is highly related to reversal of ventricular dysfunction. Compared to historically higher mortality rates, recent reports describe better outcome, probably because of advances in medical care. Based on current information, future pregnancy is usually not recommended in patients who fail to recover normal heart function. CONCLUSION: PPCM is a rare but serious form of cardiac failure affecting women in the last months of pregnancy or early puerperium. Its aetiopathogenesis is still poorly understood. Introduction of echocardiography has made diagnosis of PPCM easier and more accurate. Prognosis is highly related to reversal of ventricular dysfunction.

Fine grains ceramics of PIN-PT, PIN-PMN-PT and PMN-PT systems: drift of the dielectric constant under high electric field.

Lead-based ferroelectric ceramics with (1-x)Pb(B1 B2)O3-xPbTiO3 formula have emerged as a group of promising materials for various applications like ultrasonic sonars or medical imaging transducers. (1-x)PMN-xPT, (1-x)PIN-xPT and ternary solutions xPIN-yPMN-zPT ceramics are synthesised using the solid state reaction method. Our objective is to achieve higher structural transition temperatures than those of PMN-PT ceramics with as good dielectric, piezoelectric and electromechanical properties. Ceramics capacitance and loss tangent are measured when the ac field of measurement increases up to E=500 V/mm. Behaviours of these materials under ac field are related to their coercive field and Curie temperature.

[Contamination of blood cultures drawn from central vein catheter and peripheral venipuncture. Prospective study of 75 pairs]. / La contamination des hémocultures prélevées sur cathéters veineux centraux et sur veine périphérique. Etude prospective de 75 couples d'hémocultures.

OBJECTIVE: To determine the frequency of contamination, the sensitivity, specificity, and predictive values of cultures done with blood drawn through a central venous catheter or peripheral venipuncture. DESIGN: Prospective cohort study of critical ill medical surgical intensive care patients in whom samples for paired culture were drawn through a central venous catheter or peripheral venipuncture during a period of 8 months (from August 1st 2001 to Mars 31st 2002). RESULTS: During the study period, 75-paired cultures were studied. Fifteen peripheral blood cultures (20%) and 27 central blood cultures (36%) were positive and 6 peripheral blood cultures (8%) and 15 central blood cultures (20%) were contaminated (P=0.034). The organism most commonly responsible for contamination was Coagulase Negative Staphylococcus (16% of central blood cultures and 6.7% of peripheral blood cultures). The frequency of contamination was of 42.9% for blood cultures drawn through a femoral central venous catheter, of 10% for jugular, and of 19% for subclavian central venous catheter (P=0.22). For catheter draws compared with peripheral venipuncture, sensitivity was 100 and 75%, specificity was 76.2 and 90.5%, positive predictive value was 44.4 and 60% and negative predictive value was 100 and 95%. CONCLUSION: Cultures of blood drawn through a catheter are more sensible and less specific than those obtained from a peripheral venipuncture and the organism most commonly responsible for contamination of blood cultures is Coagulase Negative Staphylococcus.