CXCR4 expression in vitreoretinal membranes

BACKGROUND/AIM: Proliferative vitreoretinopathy (PVR) and macular pucker (MP) vitreoretinal membranes are caused by abnormal cell migration. By their role in chemotactism, chemokine receptors represent good candidates to sustain this process. The authors thus investigated the expression of one of them, CXCR4, in these pathologies. METHODS: Three PVR and four MP membranes were surgically removed and processed for immunochemical studies with antibodies for CXCR4, cytokeratins or smooth muscle actin. RESULTS: CXCR4 expression was found in all membranes. There was no relation between severity of PVR or MP and presence of CXCR4. In addition, there was no difference in CXCR4 expression between MP and PVR. CONCLUSION: CXCR4 is expressed in PVR and MP. Further experiments are needed to test if CXCR4 and other chemokine receptors are implicated in vitreoretinal membrane formation.     

Chronic endophthalmitis

Chronic endophthalmitis are intraocular infections, characterized by late onset and prolonged evolution. They are either of exogenous or endogenous origin and may be related to the penetration of "fastidious bacteria", mycoses or viruses. Diagnosis is based on specific techniques, including direct examination peroperatively, prolonged cultures on special medium and electron microscopic analysis. Treatment often combines diagnostic/therapeutic vitrectomy and intraocular injection of antibiotics. Their evolution is usually made of successive reactivations and explanting of the artificial lens is often necessary for a definitive remission in pseudophakic patients.     

Use of polar organic chemical integrative samplers to assess the effects of chronic pesticide exposure on biofilms

The responses of aquatic organisms to chronic exposure to environmental concentrations of toxicants, often found in mixtures, are poorly documented. Here passive sampler extracts were used in experimental contamination of laboratory channels, to investigate their effects on natural biofilm communities. A realistic mixture of pesticides extracted from Polar Organic Chemical Integrative Samplers was used to expose biofilms in laboratory channels to total pesticide concentrations averaging 0.5 ± 0.1 μg l^?1. The level of exposure was representative of field conditions in terms of relative proportions of the substances but the exposure concentration was not maintained (decreasing concentrations between contamination occasions). The impact on the structural as well as the functional characteristics of the autotrophic and heterotrophic components was determined, using biofilm grown in uncontaminated conditions (reference site) and in sites exposed to pesticides (contaminated site). The exposure imposed did not significantly modify the structure or functions of reference biofilms, nor did it modify tolerance as measured by mixture EC₅₀ (EC₅₀ mix). In contrast, the communities from the more contaminated downstream section lost tolerance following decreased dose exposure, but community composition remained fairly stable. Overall, these results indicate that low levels of contamination did not lead to strong changes in community structure, and 14-day changes in tolerance seemed to depend mainly on physiological adaptation, suggesting that other environmental factors or longer-lasting processes prevailed. This study reports the first attempt to use passive sampler extracts as a realistic composite contaminant for experimental exposure of biofilms, with promising perspectives in further ecotoxicology studies.     

Nocturnal oscillations in plasma renin activity during sleep in hypertensive patients: the influence of perindopril

In previous studies, we established a strong concordance between nocturnal oscillations in plasma renin activity (PRA) and REM-NREM sleep cycles. To determine whether this relation persists in the case of moderate essential hypertension and if it is influenced by antihypertensive therapies affecting renin release, six normal subjects and six hypertensive patients were studied. The normal subjects underwent one control night. The hypertensive patients were studied during a first night when a placebo was given. Four of them underwent a second night following a single dose of an angiotensin-converting enzyme (ACE) inhibitor, perindopril; and a third night, 45 days later, with the antihypertensive treatment. In addition, two of the patients underwent two night-studies, after a single and repeated doses of a beta-blocker, atenolol, to see whether preventing renin release modified the sleep structure. The relationship between the nocturnal PRA oscillations and the sleep stage patterns persisted in hypertensive patients receiving placebo. In patients who had low PRA levels, the increases associated with NREM sleep were small. However, the mean relative amplitude of the oscillations, expressed as a percentage of the nocturnal mean, was about 60%, which was similar to that in normotensive subjects. Active renin and PRA oscillations were closely coupled. ACE activity profiles displayed damped fluctuations and no systematic relationship with sleep stages.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sleep during prolonged heat exposure in man

The interaction between sleep and thermoregulation was studied in man during prolonged heat exposure. Acclimation effects were observed in thermoregulation, the sweating rate increasing to a maximum in the first nights of heat exposure and then declining until the end of the period. No acclimation effects were found in sleep parameters. REM sleep was the sleep stage most affected by the heat load. During recovery, after effects in sleep parameters were also observed.     

Adaptation of the Autobac system to the determination of serum concentrations of antibiotics

Adaptation of the Autobac system to the determination of antibiotic concentrations in the serum. In face of increasing interest in antibiotic assays, particularly for those effective within a narrow range, we have combined the Autobac system with a rapid microbiological assay in liquid medium which involves the use of a laser nephelometer. This method is rapid, simple, accurate and inexpensive. It allows laboratories with the Autobac system to monitor closely antibiotic treatments.     

Reliability of a new device to assess the oxygen consumption of human respiratory muscles.

PURPOSE: This study tests the reliability of a new device for assessing the oxygen consumption of the respiratory muscles (VO2 resp.). METHODS: Fourteen healthy male volunteers participated in the study. The device consists of an expandable external ventilatory dead space created with pieces of plastic tubing and a spirometer filled with 100% oxygen. It also incorporates a carbon dioxide absorber. Total VO2 (VO2 tot.) was recorded from the spirometric closed circuit and ventilation (V(E)), from the spirometer tracing. For each subject the test procedure was carried out in duplicate (T1 and T2) after an overnight fast. The dead space was increased at a constant rate of 260 mL every 90 s, and VO2 tot. and V(E) increased progressively. Because log VO2 tot. was linearly related to V(E), we calculated the slope value (log VO2-V(E)) and the Y-intercept (VE = 0) of the semilog regression representing, respectively, VO2 resp. and metabolic VO2 (VO2 met.). RESULTS: When compared with values in the literature, these values did not differ from those recorded in subjects of a similar age group. The VO2 resp. and VO2 met. calculated in T1 and T2 were not different (VO2 resp. = 0.0066 +/- 0.0005 for T1 vs 0.0067 +/- 0.0005 log mL x min(-1)/L x min(-1) for T2 and VO2 met. = 269.3 +/- 28.6 for T1 vs 281.9 +/- 24.1 mL x min(-1) for T2). The coefficients of variation were: 25% at T1 and 23% at T2 for VO2 resp. and 34% at T1 and 29% at T2 for VO2 met. Moreover, significant correlations (r = 0.96, P < 0.001 for VO2 resp., r = 0.95, P < 0.001 for VO2 met.), high coefficients of determination (r2 = 0.92 for VO2 resp., r2 = 0.90 for VO2 met.) and negligible SEE (0.0005 for VO2 resp., 0.2 mL x min(-1) for VO2 met.) were found between the two tests. When we plotted the mean values of VO2 resp. and VO2 met. measured at T1 and T2 against their respective differences, more than 95% of the slight differences ranged between the limits defined by mean value +/- 2 SD, reflecting the small discrepancy between duplicate measurements. CONCLUSION: The results confirm that the test performed with this device is useful and reliable for assessing the VO2 resp. in healthy subjects.     

Prise en charge anesthésique d’un accouchement chez une patiente atteinte d’un déficit en inhibiteur de C1 estérase

Hereditary and acquired angioedema (HAE/AAE) are the clinical translation of a qualitative or a quantitative deficit of C1 esterase inhibitor (C1 INH). The frequency and severity of clinical manifestations vary greatly, ranging from a moderate swelling of the extremities to obstruction of upper airway. Anaesthesiologists and intensivists must be prepared to manage acute manifestations of this disease in case of life-threatening laryngeal edema. Surgery, physical trauma and labour are classical triggers of the disease. The anaesthesiologists should be aware of the drugs used as prophylaxis and treatment of acute attacks when considering labour and caesarean section. Androgens are contraindicated during pregnancy. If prophylaxis is required, tranexamic acid may be used with caution. The safest obstetric approach appears to be to administer a predelivery infusion of C1 INH concentrate. It is important to avoid manipulation of the airway as much as possible by relying on regional techniques. We report the case of a patient suffering from an HAE discovered during pregnancy. The management included administration of C1 INH during labor and early epidural analgesia for pain relief. A short review of the pathophysiology and therapeutic options follows.