Effect of Temperature, pH and Plasmids on In Vitro Biofilm Formation in Escherichia coli.

Acid resistance (AR) in Escherichia coli is an important trait that protects this microorganism from the deleterious effect of low-pH environments. Reports on biofilm formation in E. coli K12 showed that the genes participating in AR were differentially expressed. Herein, we investigated the relationship between AR genes, in particular those coding for specific transcriptional regulators, and their biofilm-forming ability at the phenotypic level. The latter was measured in 96-well plates by staining the bacteria attached to the well, following 24-hour growth under static conditions, with crystal violet. The growth conditions were as follows: Luria Bertani (LB) medium at neutral and acidic pH, at 37°C or 25°C. We observed that the three major transcriptional regulators of the AR genes (gadX, gadE, gadW) only marginally affected biofilm formation in E. coli. However, a striking and novel finding was the different abilities of all the tested E. coli strains to form a biofilm depending on the temperature and pH of the medium: LB, pH 7.4, strongly supported biofilm formation at 25°C, with biofilm being hardly detectable at 37°C. On the contrary, LB, pH 5.5, best supported biofilm formation at 37°C. Moreover, we observed that when E. coli carried a plasmid, the presence of the plasmid itself affected the ability to develop a biofilm, typically by increasing its formation. This phenomenon varies from plasmid to plasmid, depends on growth conditions, and, to the best of our knowledge, remains largely uninvestigated.

[Tuberculosis of the thoracic wall. Presentation of 4 personal cases and review of the literature]. / La tuberculose de la paroi thoracique. Mise au point à partir de 4 observations personnelles et d'une revue de la littérature.

The thoracic wall is an uncommon localization for tuberculosis, accounting for an estimated 1 to 5% of all cases of bone and joint tuberculosis which themselves account for 15% of all extrapulmonary localizations. Four patients were hospitalized for tuberculosis of the thoracic wall. The first patient, aged 22 years, had sternal tuberculosis with multiple bone localizations. The second patient was 37 years old and had a cold abscess of the peristernal soft tissues with several other bone localizations devoid of clinical manifestations. A third 37-year-old patient had a cold intercostal abscess revealed by a mass in the upper left quadrant of the left breast. In the last patient, 50 years old, tuberculosis of the ribs was associated with a cold tumor of the knee. Together with cases reported in the literature, these observations demonstrate the difficult diagnostic situation presented by tuberculosis of the thoracic wall. Treatment is based on long-duration multi-drug therapy. Surgical resection is rarely indicated. Cure was achieved in our four cases.

[Multiple hydatid cysts of the thigh: the role of magnetic resonance imaging]. / Hydatidose multiple de la cuisse: place de l'imagerie par résonance magnétique.

Hydatid cysts of the thigh are uncommon in our country despite a high frequency of hydatic disease which is estimated to affect 5.33% of the general population. Diagnosis is usually made late in the clinical course. Ultrasonography, CT scan and magnetic resonance imaging are the most helpful diagnostic tools. We report a case of a 76-year-old female smoker who had undergone surgery for a hydatic cyst of the right lung at the age of 56 years. In June 1997, the patient was admitted for decompensation of chronic obstructive lung disease. Physical examination revealed a 6 cm painless mass in the right thigh which had developed progressively over the last year. Ultrasonography showed multiple hydatic cysts. Magnetic resonance imaging confirmed the diagnosis, showing interconnected multivesicular cystic formations. Medical treatment was given due to respiratory failure and patient refusal of a surgical procedure.

[Pulmonary embolism of hydatic origin]. / Embolie pulmonaire d'origine hydatique.

BACKGROUND: The right ventricle is an exceptional localization for hydatic cysts. There is a risk of hydatic embolism and chronic or acute cor pulmonale. CASE REPORT: A 63-year-old-man with an uneventful history was hospitalized for dry cough, exercise-induced dyspnea and bloody expectorations which had developed over the previous year. Multiple and bilateral opacities were visualized on the standard chest x-ray and the right border of the heart showed a bulge in the middle portion. Signs of right-sided hypertrophy were seen on the ECG. Imaging findings led to the diagnosis of multiple organ hydatiasis involving the lung, the liver the mediastinum and a ruptured hydatic cyst in the right ventricle. The cavogram revealed defect images in the superior vena cave and the pulmonary angiogram confirmed the diagnosis of hydatic embolism. Medical treatment was given but the patient died 8 months after diagnosis. DISCUSSION: Hydatic pulmonary embolism generally occurs after rupture of a hydatic cyst in the right ventricle or due to venous migration of daughter vesicles to the right heart then the pulmonary artery. Clinical manifestations are not specific although hemoptisy is the most frequent sign. Positive diagnosis, guided by echocardiographic findings, is based on the pulmonary arteriogram. Prognosis is particularly poor and depends of the patient's general status as well as the number and size of the embolized vessels. Survival rate is poor. Open heart surgery is indicated in localized forms.

Massive pleural effusion in systemic lupus erythematosus: thoracoscopic and immunohistological findings.

Small to moderate, bilateral pleural effusions are common during the course of systemic lupus erythematosus (SLE). These are related to several complications, particularly, congestive heart failure, nephrotic syndrome, pulmonary embolism or SLE itself. Thoracoscopy performed for a massive unilateral pleural effusion in a patient with SLE and inferior vena cava thrombosis revealed several small nodules on the visceral pleura. Immunofluorescence studies of biopsy samples showed immunoglobulin deposits confirming the lupus-related origin of the pleuritis.

[Pleurodesis. Indications and review of symphyseal agents]. / La pleurodèse. Indications et revue des agents symphysants.

Recurrent or chronic pneumothorax and neoplasm of the pleura are the major indications for pleurodesis. However certain chronic or recurrent forms of pleural affections of mechanical origin or secondary chylothorax may not respond to aetiologic treatment and could benefit from therapeutic pleural symphysis. The objective may be reached with several physical and chemical agents including cyclins and talcum powder among the most effective products devoid of major risk. The classic surgical techniques have been abandoned in favour of interventional thoracoscopy to obtain pleural abrasion and pleurectomy. Promising results have been obtained.

[Tracheobronchopathia osteochondroplastica. Personal observation and review of the literature]. / La trachéobronchopathie chondro-ostéoplastique. Mise au point à propos d'une observation personnelle et d'une revue bibliographique.

Tracheobronchobathia osteoplastica (TBO) is a benign disease first described in 1855 and rather rare since only 371 cases have been reported so far. The disease is characterized by the presence of subepithelial osteocartilaginous focal lesions without any relation to tracheal rings. The mechanism of its occurrence remains controverted. We report a case of TBO which is particular in that is was associated with atrophic rhinitis, polydactylia and disorder of oesophageal motricity. From a compilation of 113 cases published by French and Anglo-Saxon authors since 1970, it appears that the clinico-radiological and laboratory picture is of little help in the positive diagnosis which in fact rests on three key-points: bronchial endoscopy, pathological examination of bronchial biopsy fragments and thoracic imaging techniques including computerized topography and magnetic resonance imaging. The usually benign course of the disease can be marked by severe complications, such as infections, haemorrhages, acute dyspnoea by extension to the larynx or significant narrowing of the tracheal lumen which may need tracheotomy or surgical resection of the lesions.

[Biological effects of pleural talc in neoplastic pleurisy]. / Effets biologiques du talcage pleural au cours des pleurésies néoplasiques.

A study was carried out on ten patients who had received talc by thoracoscopy for secondary neoplastic pleural involvement. The study was in two parts. First, a laboratory study on blood specimens was made including the full blood count, sedimentation rate and alpha-2 globulins. Secondly, the pleural liquid was examined over a 24 hour period, measuring the leucocyte count/ml and also the pleural sugar. The studies revealed the occurrence of an early rise (J0) in the level of polynuclear neutrophil (PNN) in the pleural liquid, with a 24 hour peak preceded by a leucocytosis and a moderate polymorphonuclear response without any change in the sedimentation rate. These changes provide evidence for the role of PNN in the genesis of pleural symphysis during talc therapy. There was also an early fall in pleural sugar, and this was in parallel with the diminution of the quantity of pleural fluid drained and would be linked to a rise in the local cellular metabolism and to a disturbance in the exchange across the thickened pleural membrane, as a result of fibrosis.

[An experimental anatomopathological study of pleural talcosis]. / Etude anatomopathologique expérimentale du talcage pleural.

The aim of this work was to study the anatomical and pathological reaction and the mechanism of the formation of the pleural symphysis during pleural talcosis. The experiment was performed on fifteen dogs of similar breed, divided into three groups of five subjects each. After thoracoscopy under general anaesthesia, 2 ml of intrapleural physiological saline were injected in group I (controls) and 2 or 4 ml of talc granules in group II and III. A drainage tube was positioned at the end of the examination. One dog in each group was sacrificed on the 1st, 2nd, 7th, 15th, and 30th days post-thoracoscopy. At autopsy a detailed macroscopic study was carried out and some biopsies were taken for histology. In the control group, the inflammatory reaction was very moderate and rapidly disappeared whereas in the groups treated with talc, the talc led to an exudate of several millimeters, the exudate of inflammatory reaction was acute and early (J1) and involved the pleural in particular on the costal surface and was more moderate on the visceral surface and only involved the lung to a thickness of 2 or 3 mm and a few peripheral alveolar spaces. The granulomatous reaction occurred later (from the 3rd day) and was accompanied by the formation of a symphysis by the deposition and coagulation of fibrin which continued from the 7th to the 15th day, and became solid on the 30th day post-thoracoscopy. There was no significant difference between the two groups treated with talc, implying that the reaction was linked to the talc and was independent of the dose used.

[Results of talc administration using thoracoscopy in neoplastic pleurisies. Apropos of 218 cases]. / Résultats du talcage pleural sous thoracoscopie au cours des pleurésies néoplasiques. A propos de 218 cas.

The authors report the results of their experience using tale pleurodesis under thoracoscopic control in the treatment of 218 cases of malignant pleural involvement. Although this technique is well tolerated it is necessary to note certain factors which prevent a successful pleurodesis (12% of cases). Thus, huge effusions greater than 12 litres, pleural involvement with large tumour masses, a very long history and patients aged more than 70 years were all factors contributing to a poor outcome. The success of pleural talc also depends on the nature of the primary cancer, for example in our series broncho-pulmonary cancers yielded better results than those effusions which were secondary to ovarian cancers.

[Lymphocytes in the peripheral blood of the dog. Initial data on the presence of receptors for human and canine red blood cells]. / Les lymphoyctes du sang periphérique du chien. Premières données sur la présence de récepteurs pur les globules rouges d'orginie humaine et caviine.

The authors studied red cells from men and various animals for their capacity to mind to canine peripherical blood lymphocytes and form spontaneous rosettes.