Monitoring the variations of the oxygen transfer rate in a full scale membrane bioreactor using daily mass balances.

Oxygen transfer in biological wastewater treatment processes with high sludge concentration, such as membrane bioreactor (MBR), is an important issue. The variation of alpha-factor versus mixed liquor suspended solids (MLSS) concentration was investigated in a full scale MBR plant under process conditions, using mass balances. Exhaustive data from the Supervisory Control And Data Acquisition (SCADA) and from additional online sensors (COD, DO, MLSS) were used to calculate the daily oxygen consumption (OC) using a non-steady state mass balance for COD and total N on a 24-h basis. To close the oxygen balance, OC has to match the total oxygen transfer rate (OTRtot) of the system, which is provided by fine bubble (FB) diffusers in the aeration tank and coarse bubbles (CB) in separate membrane tanks. First assessing OTR(CB) then closing the balance OC = OTRtot allowed to calculate OTR(FB) and to fit an exponential relationship between OTR(FB) and MLSS. A comparison of the alpha-factor obtained by this balance method and by direct measurements with the off-gas method on the same plant is presented and discussed.

[Cryptococcal meningitis disclosed by visual loss in HIV negative patient with ventriculo-atrial shunting]. / Cryptococcose neuroméningée révélée par une baisse de l'acuité visuelle chez un patient atteint de neurosarcoïdose et porteur d'une dérivation ventriculoatriale.

INTRODUCTION: HIV infection is the main cause of cryptococcal neuromeningitis but other diseases may be associated with this infection. CASE REPORT: We report a case of cryptococcal neuromeningitis in a patient with sarcoidosis and ventriculoatrial shunting. The patient was successfully treated by effective therapy without device withdrawal. CONCLUSION: The relationship between cryptococcosis and sarcoïdosis has been already described and may be not fortuitous. However it remains a very rare complication of sarcoidosis. Because of its potential severity (mortality rate of 40%), the diagnosis of cryptococcosis should be evoked as a differential diagnosis of neuro-sarcoidosis.

Effects of glucocorticosteroids and glucagon on argininosuccinate synthetase, argninosuccinase, and arginase in fetal rat liver.

In the present study we examined the in vivo effects of glucocorticosteroids and glucagon on the developmental formation of the individual urea cycle enzymes argininosuccinate synthetase, argininosuccinase, and arginase during the late fetal period. In particular, addition of exogenous glucagon caused a rise in argininosuccinase and arginase activities in the livers of rat fetuses at term but not at earlier stages. Glucagon produced a rise in argininosuccinase activity earlier if fetuses were previously treated with cortisol. When fetuses were deprived of corticosteroid (hypophysectomy in utero), glucagon no longer promoted the argninosuccinase activity, indicating that adrenal glucocorticoids are required for normal enhancement of the enzyme activity by glucagon. Dibutyryl cAMP was still effective in hypophysectomized fetuses. Results obtained by injected combinations of inducers indicated that a glucocorticosteroid-glucagon interaction might be involved in the regulation of argininosuccinate synthetase and argininosuccinase. No synergistic action was found on arginase activity in vivo.

Effects of pancreatic hormones and glucocorticosteroids on argininosuccinate synthetase and argininosuccinase activities of rat liver during the perinatal period: in vivo and in vitro studies.

The activity changes of two urea cycle enzymes, argininosuccinate synthetase (ASS) and argininosuccinase (ASL), were followed after corticosteroid and pancreatic hormone treatments in utero and in primary cultured fetal hepatocytes. The ASL activity which was induced by glucagon or by (Bu)2cAMP administration was enhanced by a treatment with streptozotocin for 2 days, although ASS was not changed under these conditions. The activity of both enzymes was enhanced by cortisol administration in utero only in streptozotocin-treated fetuses, suggesting an inhibitory effect of insulin. In cultured fetal hepatocytes, dexamethasone produced a marked increase of the two enzyme activities, which was abolished by the simultaneous addition of insulin. The parallel results obtained with these two experimental models allow one to conclude that the high plasma insulin level in late gestation might repress the development of ASS and ASL activities in utero and antagonize the effect of corticosteroids on these enzyme activities.

AMP-activated protein kinase counteracted the inhibitory effect of glucose on the phosphoenolpyruvate carboxykinase gene expression in rat hepatocytes.

The effect of AMP-activated protein kinase (AMPK) in the regulation of the phosphoenolpyruvate carboxykinase (PEPCK) gene expression was studied in isolated rat hepatocytes. Activation of AMPK by AICAR counteracted the inhibitory effect of glucose on the PEPCK gene expression, both at the mRNA and the transcriptional levels. It is proposed that a target for AMPK is involved in the inhibitory effect of glucose on PEPCK gene transcription.

Cell swelling increased the alpha2-macroglobulin gene expression in cultured rat hepatocytes.

The effect of cell swelling on the expression of the alpha2-macroglobulin (alpha2M) gene was studied in hepatocytes in culture. Hypoosmolarity induced an increase (3-fold increase) in the level of alpha2M mRNA through a corresponding stimulation of the rate of transcription of the alpha2M gene. The addition of raffinose (100 mM) corrected the effect of hypoosmolarity at both mRNA and transcriptional level, demonstrating that cell swelling per se was responsible for the observed effect on the expression of the alpha2M gene. Moreover, the effect of cell swelling was additive to that of interleukin 6, a major mediator of the acute-phase response.

Glutamine accelerates interleukin-6 production by rat peritoneal macrophages in culture.

The effect of glutamine on the production of interleukin-6 (IL-6) was studied in rat peritoneal macrophages in culture. A maximal production of IL-6 was measured at 4 h in lipopolysaccharide (LPS)-stimulated macrophages, and addition of glutamine (5 mM) anticipated this increase by 1 h without any increase in the IL-6 mRNA level. The effect of glutamine required the presence of LPS. Thus, glutamine accelerates IL-6 production from the pre-existing mRNA. The effect of glutamine was not mediated by cell swelling since culture of macrophages in hypoosmotic condition decreased the production of IL-6 in the culture medium with a corresponding decrease in the IL-6 mRNA level.

Hypoosmolarity and glutamine increased the beta-actin gene transcription in isolated rat hepatocytes.

The mechanism of action of hydration state was studied on beta-actin gene expression in isolated hepatocytes. Results obtained with Northern blot analysis and run on transcription assays show that hypoosmolarity increased and hyperosmolarity decreased the beta-actin mRNA level through a corresponding modulation of the rate of the gene transcription. Glutamine, which is known to induce cell swelling, also increased the beta-actin mRNA level in a dose-dependent manner and induced a stimulation of the beta-actin gene transcription. Thus, cell hydration state regulates gene expression in the liver through a transcriptional mechanism.

Protein synthesis is involved in the modulation of the level of the phosphoenolpyruvate carboxykinase mRNA by changes in cell volume in isolated rat hepatocytes.

The mechanism of action of hydration state was studied on phosphoenolpyruvate carboxykinase (PCK) gene expression in isolated rat hepatocytes. Hypoosmolarity decreased the level of the PCK mRNA after a lag period of about 60 min. The decreasing effect of hypoosmolarity was totally blocked by inhibitors of both protein synthesis and gene transcription. Moreover, hypoosmolarity specifically increased the synthesis of a 45000 Mr protein, which decreased in the presence of inhibitors of transcription. A close relationship between the synthesis of the 45000 Mr protein and the decrease in the PCK mRNA level was observed, suggesting that this protein might potentially be involved in the regulation of the level of the PCK mRNA by cell swelling.

Cell swelling activates STAT1 and STAT3 proteins in cultured rat hepatocytes.

In this paper, we demonstrated that in cultured rat hepatocytes cell swelling induced the activation of STAT1 and STAT3 proteins without any effect on STAT4, STAT5 and STAT6 proteins. Cell swelling induced an activation of STAT proteins through an increase in the phosphorylation of the tyrosine residue also phosphorylated by interleukin-6, but without any activation of JAK kinases. The signaling pathway by which cell swelling activated STAT1 and STAT3 is discussed.

[Effects of glucocorticosteroids on enzymatic activity in the urea cycle in fetal rat liver]. / Effets des glucocorticostéroïdes sur l'activité des enzymes du cycle de l'urée dans le foie foetal de rat

The five urea cycle enzyme activities of rat liver are followed during late fetal period and the first day of life. All five enzymes exhibit relatively low activities in foetal liver and a rapid postnatal increase. Lack of glucocorticosteroid (after hypophysectomy in utero) induces an important decrease of activity of three enzymes: carbamyl phosphate synthetase, ornithine transcarbamylase and argininosuccinate synthetase. Treatment with hydrocortisone acetate on decapitated fetuses results in a marked stimulation of the activity of four of the enzymes: carbamyl phosphate synthetase, ornithine transcarbamylase, argininosuccinate synthetase and arginase. Premature induction of carbamyl phosphate synthetase activity is obtained after intraperitoneal injection with hydrocortisone acetate at 16,5 days of gestation.

Glutamine and regulation of gene expression in mammalian cells. Special reference to phosphoenolpyruvate carboxykinase (PEPCK).

The repertoire of the actions of specific amino acids on gene expression is relatively limited in mammalian cells. Glutamine constitutes the most studied amino acid and recent works intended to demonstrate its mechanism of action on two genes: the beta-actin and the phosphoenolpyruvate carboxykinase genes. From these studies, it appears that glutamine may regulate gene expression by, at least, two different mechanisms: one through the glutamine-induced cell swelling, and another through its intracellular metabolism. The involvement of phosphatidylinositol 3-kinase in the signaling pathway triggered by cell swelling is discussed.

Glutamine and regulation of gene expression in rat hepatocytes: the role of cell swelling.

Glutamine is able to regulate the expression of various genes in rat hepatocytes. This includes genes coding for proteins involved in glutamine utilization, such as argininosuccinate synthetase (ureagenesis) or phosphoenolpyruvate carboxykinase (gluconeogenesis). Moreover, glutamine is also able to stimulate the expression of genes involved in the acute-phase response, such as the alpha 2-macroglobulin gene. The effect of glutamine on the regulation of gene expression may be explained, at least in part, by the cell swelling due to its sodium-dependent transport. The physiological significance of the effect of glutamine is discussed.

[Idiopathic hypotension of the cerebrospinal fluid]. / Hypotension idiopathique du liquide céphalo-rachidien.

A case of spontaneous hypotension of the cerebrospinal fluid (CSF) is reported. A 32 years-old woman was complaining of intense orthostatic headaches. CT scan showed slit ventricles and the spinal tap showed a pressure of the CSF too low to be measured. A sample of clear CSF could only be obtained by aspiration. The patient's status improved without drugs by simply staying in bed for one week. Few similar cases have been reported. The mechanisms of this disorder still remains unknown.

[Glutamine and the liver cell: metabolism, properties and the concept of metabolic regulation by cell swelling]. / Glutamine et cellule hépatique: métabolisme, propriétés et concept de régulation du métabolisme par le gonflement cellulaire.

Glutamine is transported into the hepatocyte in a sodium-dependent manner. A consequence of the sodium-dependent entry of glutamine is an osmotic swelling of the cell. In the past, glutamine has been given a number of anabolic properties such as the stimulation of both glycogen and lipid synthesis from glucose. The mechanism through which glutamine activates key enzymes in these metabolic pathways involves the glutamine-induced cell swelling. Moreover, glutamine regulates gene expression of the beta-actin gene at a transcriptional level as well as that of the phosphoenolpyruvate carboxykinase gene by stabilizing its mRNA. Regulation of gene expression by glutamine also involves the cell swelling phenomena. Cell swelling is now regarded as a novel regulatory element of hepatic metabolism.

[Optical coherence tomography: a reliable tool for localisation of macular hemorrhage. Two case reports]. / Intérêt de la tomographie par cohérence optique pour localiser une hémorragie maculaire. A propos de deux cas.

Recent observations have found that premacular hemorrhage in Valsalva retinopathy is located under the internal limiting membrane. We confirm these findings in two case reports of Valsalva retinopathy. Visual acuity rehabilitation was obtained in the first case by conservative treatment and by draining the hemorrhage into the vitreous with Neodymium (Nd):Yag laser in the second case. We report the current therapeutic guidelines for Valsalva retinopathy, including the systematic search of autosomal dominant syndrome of retinal arterial tortuosity, a rare condition, often discovered after this type of benign macular hemorrhage.