Differences in Wear and Material Integrity of NAO and Low-Steel Brake Pads under Severe Conditions.

In this study, through severe reduced-scale braking tests, we investigate the wear and integrity of organic matrix brake pads against gray cast iron (GCI) discs. Two prototype pad materials are designed with the aim of representing a typical non-metal NAO and a low-steel (LS) formulation. The worn surfaces are observed with SEM. The toughness of the pad materials is tested at the raw state and after a heat treatment. During braking, the LS-GCI disc configuration produces heavy wear. The friction parts both keep their macroscopic integrity and wear appears to be homogeneous. The LS pad is mostly covered by a layer of solid oxidized steel. The NAO-GCI disc configuration wears dramatically and cannot reach the end of the test program. The NAO pad suffers many deep cracks. Compacted third body plateaus are scarce and the corresponding disc surface appears to be very heterogeneous. The pad materials both show similar strength at the raw state and similar weakening after heat treatment. However, the NAO material is much more brittle than the LS material in both states, which seems to favor the growth of cracks. The observations of crack faces suggest that long steel fibers in the LS material palliate the brittleness of the matrix, even after heat damage.

Automated inference procedure for the determination of cell growth parameters.

The growth rate and carrying capacity of a cell population are key to the characterization of the population's viability and to the quantification of its responses to perturbations such as drug treatments. Accurate estimation of these parameters necessitates careful analysis. Here, we present a rigorous mathematical approach for the robust analysis of cell count data, in which all the experimental stages of the cell counting process are investigated in detail with the machinery of Bayesian probability theory. We advance a flexible theoretical framework that permits accurate estimates of the growth parameters of cell populations and of the logical correlations between them. Moreover, our approach naturally produces an objective metric of avoidable experimental error, which may be tracked over time in a laboratory to detect instrumentation failures or lapses in protocol. We apply our method to the analysis of cell count data in the context of a logistic growth model by means of a user-friendly computer program that automates this analysis, and present some samples of its output. Finally, we note that a traditional least squares fit can provide misleading estimates of parameter values, because it ignores available information with regard to the way in which the data have actually been collected.

[Differential modulation of TLR2 and TLR4-induced TNF production by murin haemorrhagic shock]. / Modulation différentielle des effets de la stimulation des récepteurs Toll-like 2 et 4 par l'état de choc hémorragique.

OBJECTIVE: To investigate the influence of haemorrhagic shock in mice on ex vivo TNF production by whole blood cells (WBC) stimulated through Toll-like receptors (TLR) 4 and 2. STUDY DESIGN AND ANIMALS: Experimental study using BALB/c male mice. METHODS: Haemorrhage (0,026+/-0,003 ml/g) by transparietal cardiac puncture under general anaesthesia. Measurement of left intraventricular pressure through a direct subcostal cardiac puncture. Possible restitution of shed blood volume (SBV) in retroorbital venous plexus, 60 minutes following haemorrhage. Lethal exsanguination 120 minutes following general anaesthesia (Control group), cardiac puncture (Sham group), blood sample (Haemorrhage group), or 60 minutes following SBV retransfusion (SBV group). Cultures (24 hours) of whole blood from the exsanguination, alone or with Escherichia coli endotoxin (LPS, TLR 4) or with heat-killed Staphylococcus aureus Cowan (SAC, TLR 2). Assessment of TNF levels in the cultures supernatant (Elisa). RESULTS: Hemorrhage (approximately 30% of calculated blood volume) resulted in arterial hypotension (-50%) which was reversed by SBV retransfusion. TNF production by LPS-stimulated WBC was reduced by haemorrhage (approximately -50%) with or without SBV retransfusion. TNF production by SAC-stimulated WBC remained unchanged. CONCLUSION: The reduction of proinflammatory cytokines production by WBC stimulated with pathogen-associated molecular patterns is not a generalized phenomenon following murin haemorrhagic shock. It depends on the used stimulus and studied signalling pathways.

Co-amoxiclav pharmacokinetics during posttraumatic hemorrhagic shock.

OBJECTIVE: To determine the effects of severe trauma with hemorrhagic shock on amoxicillin and clavulanate concentrations in plasma and their pharmacokinetics. DESIGN: A prospective, open, descriptive study. SETTING: A 12-bed, adult surgical intensive care unit in a university-affiliated hospital in France. SUBJECTS: Subjects were 12 patients (10 men, 2 women) with severe trauma: median (range) Injury Severity Score, 38 (17-48); Acute Physiology and Chronic Health Evaluation II, 16 (7-38); Simplified Acute Physiology Score II, 41 (23-77). Also enrolled were 12 healthy volunteers who were matched on age (+/-5 yrs), gender, and body-surface area (+/-20 cm2). All the trauma patients suffered hemorrhagic shock defined as the association of at least one episode of systolic blood pressure <90 mm Hg and an intravascular volume expansion >2000 mL between trauma and surgery. INTERVENTION: Prophylactic perioperative administration of 2 g of amoxicillin and 0.2 g of clavulanate in combination during the first 12 hrs posttrauma in patients, and at the start of the pharmacokinetic study in volunteers. MEASUREMENTS AND MAIN RESULTS: Serial plasma samples (n = 13) were obtained after the first antibiotic administration to measure antibiotic levels by using high-performance liquid chromatography assays. Compared with volunteers, trauma patients had higher plasma amoxicillin and clavulanate concentrations, attributed to a reduction of the volume of distribution (p =.001 and p =.06, respectively) and, to a lesser extent, of the total body clearance (p =.09 and p =.20, respectively). Consequently, amoxicillin and clavulanate elimination half-lives were similar for the two groups of subjects. The interindividual variabilities for all the amoxicillin pharmacokinetic parameters were higher in patients. CONCLUSIONS: In trauma patients with hemorrhagic shock requiring surgery, the administration of 2 g of amoxicillin and 0.2 g of clavulanate seems adequate, according to the antibiotic concentrations observed in plasma for both drugs. However, further studies exploring antibiotic concentrations in tissues are warranted.

[Colonization by methicillin-resistant Staphylococcus aureus is a predictive factor for the resistance phenotype of an infectious strain of S. aureus]. / La colonisation par Staphylococcus aureus résistant à la méticilline est un facteur prédictif du phénotype de résistance d'une souche infectante de S. aureus.

OBJECTIVE: To assess the predictive value of a previous colonization with methicillin-resistant Staphylococcus aureus for the resistance pattern of a bacteriological specimen significantly positive to S. aureus. STUDY DESIGN: Retrospective study of patients' files. PATIENTS: Patients admitted for at least 48 hours in a surgical intensive care unit from April 1, 1996 to December 31, 1997. METHODS: Collection of patients' characteristics and chronology of positive microbiological specimens with methicillin-susceptible (MSSA) or -resistant (MRSA) S. aureus from medical and laboratory records. During the study period, screening for nasal or perineal colonization with MRSA was systematically performed on admission and weekly thereafter. RESULTS: The files of 540 patients were reviewed. MSSA and MRSA infections occurred in 7% (39/540) and 4% (20/540) of the patients respectively. By opposition with MSSA infections, MRSA infections occurred more frequently in patients previously colonized with MRSA (13 infections in 63 colonized patients [21%] versus 7 infections in 477 non-colonized patients [2%], odds ratio = 18, confidence interval: 6-51, P < 0.0001). The median delay between colonization and infection was 5 days. The positive and negative predictive values for previous colonization with MRSA to predict infection with MRSA in presence of a bacteriological specimen significantly positive with S. aureus were 81 and 84%, respectively. CONCLUSION: The probabilistic use of a glycopeptide in presence of a bacteriological specimen significantly positive with S. aureus should be limited to patients already colonized with MRSA, in order to decrease the abusive administration of these antibiotics.

Effect of Strongyloides stercoralis infection and eosinophilia on age at onset and prognosis of adult T-cell leukemia.

Onset of adult T-cell leukemia (ATL) usually follows a long period of viral latency. Strongyloides stercoralis infection has been considered a cofactor of leukemogenesis. Hypereosinophilia (HE) is also observed and could be associated with either the presence of parasites or the leukemic process. In non-Hodgkin's lymphoma, eosinophilia may or may not affect prognosis. To determine whether infection with S stercoralis and therefore eosinophilia has a significant effect on the development of ATL, we studied two variables in 38 patients: age at onset and median survival rate. Infected (Ss+) patients (n = 19) were younger (P = .0002) and survived longer (P = .0006) than uninfected (Ss-) patients (n = 19) (median age, 39 vs 70 years; median survival, 167 vs 30 days). Mean survival of patients with hypereosinophilia (HE+) was not significantly different from that of patients without hypereosinophilia (HE-) (P = .57). However, overall survival was longer for Ss + HE + patients than for Ss-HE-patients (P = .01; 180 vs 30 days) or Ss-HE + patients (P = .03; 180 vs 45 days). Among patients with mean survival more than 180 days, Ss + HE + patients survived longer (P = .028). Our data confirm that cofactors related to the environment, such as S stercoralis and hypereosinophilia associated with S stercoralis or human T-cell leukemia virus, type 1 (HTLV-1) might be important in HTLV-1-associated leukemogenesis and suggest that hypereosinophilia affects the prognosis of HTLV-1-associated leukemia.

[Adenoma of the choledochus]. / Les adénomes du cholédoque.

Two patients with signs of an obstructed main bile duct underwent surgery. Choleductectomy was performed followed by Mirizzi exploration. Extemporaneous pathology examination of the intra-ductal tissue revealed benign adenoma of the main bile duct. Resection of the main bile duct with hepato-duodenal anastomosis was performed in the first patient and resection with end-to-end anastomosis in the second.

[Strongyloides stercoralis in T-cell leukemia/lymphoma in adults and acquired immunodeficiency syndrome]. / Strongyloides stercoralis dans la leucémie/lymphome T de l'adulte et le syndrome d'immunodéficience acquise.

The mechanisms of chronic infestation by Strongyloides stercoralis (Ss) are unknown. Immunodepression is classically evoked to explain the proliferation of the parasite that is sometimes massive and overwhelming. We present here two retrospective studies of 13 cases of strongyloidiasis (three disseminated strongyloidiasis) out of 26 patients with adult T-cell leukemia/lymphoma (ATL) and of ten cases of strongyloidiasis out of 98 patients with AIDS. Ten patients out of 98 were dually infected with both HIV and HTLV-1: 2/10 also infected by Ss. The frequency of Ss infection appears higher in ATL patients when compared with AIDS patients (P < 0.001). Ss-infected ATL patients were younger than those uninfected (P < 0.01). Ss-infected AIDS patients were older than the ones uninfected (p < 0.03). No significative difference was found between ATL and AIDS patients who were over 40 years-old. These data suggest that 1) the particular type of immunodepression produced early by HTLV-1 is more favorable to the development of Ss infection than the one associated with HIV, 2) the latency of expression of HTLV-1, prior to the development of leukemia, is reduced in Ss-infected patients, 3) Ss infection may slow down VIH pathogenic activity.

[Splenic localization of von Recklinghausen's disease]. / Localisation splénique de la maladie de von Recklinghausen.

The authors report about one case of splenic site in a polyvisceral involvement by von Recklinghausen's disease. This site was not found in the literature. Since it was impossible to confirm the benignancy of the lesions, the degenerative risks of which are well known, the authors carried out partial gastrectomy and splenectomy.

[Primary malignant melanoma of the small intestine]. / Mélanome malin primitif de l'intestin grêle.

The small intestine is a frequent site for metastases of cutaneous or ocular melanoma. When the latter are absent, the diagnosis of primary intestinal melanoma can be proposed. Primary malignant melanoma of the small intestine arises from melanoblastic cells of the neural crests, which migrate to the distal ileum through the omphalomesenteric canal. Incomplete regression of the later leads to persistence of Meckel's diverticulum. We report herein a case of malignant melanoma of the small intestine without evidence of a cutaneous and/or ocular origin. Based on its location in the distal ileum, we propose that this tumor be classified as a primary malignant melanoma of the small intestine.

The use of calcium antagonists to treat intra-operative hypertension--evaluation of efficacy and safety of a new dihydropyridine derivative, intravenous isradipine, during abdominal surgery.

Twenty-three patients who developed intraoperative hypertension (mean arterial pressure greater than 110 mmHg) during abdominal surgery under balanced general anaesthesia were randomly assigned to two groups. The isradipine group (n = 12) received 0.5 mg of isradipine, and the placebo group (n = 11) received 10 ml of isradipine solvent over a 5-min period in a blind manner. Arterial pressure was recorded 12 min after the injection was started. If the mean arterial pressure had not decreased by at least 10% at 12 min, patients received in an open manner 0.5 mg of isradipine. None of the patients in the isradipine group received isradipine in an open manner, in contrast with nine of the 11 patients in the placebo group (P less than 0.0001, Fisher's exact test). During both the blind period and the open trial, isradipine induced a 40% decrease in systolic, diastolic, and mean arterial pressures within the first two min of infusion. Arterial pressure remained below the pre-isradipine injection values for at least 45 min. Transient hypotension (mean arterial pressure less than 70 mmHg) was noted in 6/21 patients (29%). Mean heart rate remained statistically unchanged during the decrease in arterial pressure in both groups, but a tachycardia (increase in heart rate greater than 20 beats min-1) was noted in 4/21 patients (19%). This study indicates that intravenous isradipine is an effective therapy with sustained efficacy for intraoperative hypertension during abdominal surgery. The safety of its use needs a close monitoring of arterial pressure.

[Three cases of solid and papillary tumors of the pancreas in black women]. / Trois cas de tumeurs solides et papillaires du pancréas chez la femme de race noire.

Three cases of solid and papillary epithelial neoplasm of the pancreas are presented. These tumors occur more commonly in young patients with a predilection for young black females. They have a good prognosis allowing conservative surgery. The histological study of the specimens strongly suggests an endocrine tumor but all histological and immunocytochemical endocrine stains are negative. The ultrastructural study of these tumors has revealed the existence of borderline forms between these tumors and endocrine tumors.

[Leiomyosarcoma of the Meckel's diverticulum and multiple diverticulosis of the ileum. Apropos of a case]. / Léïomyosarcome du diverticule de Meckel et diverticulose multiple du grêle. A propos d'un cas.

We report a case of a leiomyosarcoma arising in a Meckel's diverticulum in a man of 90 years, with multiple ileal diverticulosis. The clinical picture was similar to acute appendicitis and diagnosis was not made until resection of an abdominal mass with histological appearance of leiomyosarcoma. 59 cases of leiomyosarcoma of Meckel's diverticulum have previously been reported in the literature. No case until now has been reported in a patient of Caribbean origin neither in association with ileal diverticulosis. Although rare, leiomyosarcoma is the commonest sarcoma of Meckel's diverticulum, and with full resection of the tumor the prognosis is very good.

[Malignant strongyloidiasis and the HTLV-I virus]. / Anguillulose "maligne" et virus HTLV-I.

A significant association between Strongyloides stercoralis and HTLV-1 infections has been demonstrated in areas (such as southern Japan and the Caribbean) where HTLV-1 is endemic. Due to the immunomodulating effects of the virus and the parasite, patients with both infections would be at risk for overwhelming strongyloidiasis as well as for T-lymphocyte haemopathy. S. stercoralis is thought to be a cofactor for viral replication and leukaemogenic power.