A model for cellulase production from Trichoderma reesei in an airlift reactor.

A mathematical model for cellulase production by Trichoderma reesei RUT-C30 grown in a cellulose medium with lactose as fed batch in an airlift reactor is proposed. To describe adequately the mass transfer between the air bubbles and the broth, it uses computational fluid dynamics (CFD) including multiphase Eulerian-Eulerian formulation, with a detailed description of the bubble size distribution through the use of the population balance model (PBM) and the class method (CM). The kinetics of the biomass growth is further coupled to the fluid flow conditions using partial differential equations for all the species involved, providing detailed information of important reactor conditions such as the distribution of oxygen, cellulose, and the shear stress within the reactor over the entire period of fermentation.

Diffusion of rhodamine B and bovine serum albumin in fibrin gels seeded with primary endothelial cells.

Scaffolds with adequate mass transport properties are needed in many tissue engineering applications. Fibrin is considered a good biological material to fabricate such scaffolds. However, very little is known about mass transport in fibrin.

Bioreactor controlled by PI algorithm and operated with a perfusion chamber to support endothelial cell survival and proliferation.

This paper reports the optimization of a perfusion bioreactor system previously reported by us (Chouinard et al., 2009). The implementation of a proportional-integral (PI) controller algorithm to control oxygen concentration and pH is presented and discussed.

Assessing a whiplash management model: a population-based non-randomized intervention study.

Objective: To evaluate the effectiveness of a multidisciplinary clinical management approach for whiplash-associated disorders (WAD) following a motor vehicle injury in Quebec.

Methods: A clinical management model was implemented in 5 geographic regions of the Province of Quebec, Canada, in 7 hospitals and 19 clinics. A 2-group population-based parallel design was used to assess its effectiveness.

Functional recovery from paraplegia caused by syphilitic meningomyelitis.

Background: Syphilitic involvement of the nervous system can present in many different ways. We report a patient who presented with rapidly evolving paraparesis secondary to syphilitic meningomyelitis.

Methods: Case report.

Secondary impairments after spinal cord injury: a population-based study.

Objective: To determine the prevalence of secondary impairments among individuals with long-standing spinal cord injury in Quebec and the potential relationships between these impairments and several variables.

Design: A review of 2,200 medical files was conducted to determine the target population; 976 patients were selected randomly and mailed questionnaires. The results were based on 482 individuals with spinal cord injury who returned the completed questionnaire.

A role for PKC epsilon and MAP kinase in bradykinin-induced arachidonic acid release in rabbit CCD cells.

Arachidonic acid (AA) release is the rate-limiting step in the production of prostaglandins, an important class of autocrine/paracrine factors that modulate collecting duct function. Previous results from this laboratory have established cytosolic phospholipase A2 (cPLA2) as the enzyme responsible for bradykinin (BK)-stimulated AA mobilization in rabbit cortical collecting duct (RCCD) cells, and the present study pursues the intracellular signaling mechanisms responsible for its activation. Pretreatment of cells with Ro-31-8220, an inhibitor of protein kinase C (PKC), or PD-98059, an inhibitor of the mitogen-activated protein kinase (MAPK) cascade, resulted in a 50-60% reduction in BK-stimulated AA release.

Bestatin-mediated inhibition of leucine aminopeptidase may hinder HIV infection.

Bestatin, an inhibitor of leucine aminopeptidase (LAPase), significantly decreased HIV infection as reflected by a reduced number of positive immunofluorescent cells, p24 levels, reverse transcriptase activity and the number of proviral copies found in Bestatin-treated cells. Cellular and extracellular LAPase activity in infected cells was higher than the LAPase activity found in uninfected cells. However, cellular and extracellular LAPase activity as well as total protein kinase C activity was lower in Bestatin-treated cells.

Bradykinin-stimulated cPLA2 phosphorylation is protein kinase C dependent in rabbit CCD cells.

We have used an established cell line of rabbit cortical collecting duct (RCCD) epithelial cells representing a mixed population of principal and intercalated cell types to determine which phospholipase A2 (PLA2) enzyme therein is responsible for bradykinin (BK)-stimulated arachidonic acid (AA) release and how its activation is regulated. BK-stimulated AA release was reduced 92% by arachidonyl trifluoromethyl ketone, an inhibitor of cytosolic PLA2 (cPLA2). Examination of PLA2 activity in vitro demonstrated that BK stimulation resulted in a greater than twofold increase in PLA2 activity and that this activity was dithiothreitol insensitive and was inhibited by an antibody directed against cPLA2.

Bradykinin-stimulated arachidonic acid release from MDCK cells is not protein kinase C dependent.

Bradykinin (BK)-induced release of arachidonic acid (AA) from Madin-Darby canine kidney (MDCK) D1 cells was investigated. Phorbol 12-myristate 13-acetate (PMA) caused a synergistic increase in BK- and A-23187-induced release of AA but alone had no effect on this release. Inhibition of protein kinase C (PKC) with bisindolmaleimide I (BIS) abolished the synergistic effects of PMA but did not affect AA release caused by BK or A-23187 alone.

Bradykinin-induced translocation of cytoplasmic phospholipase A2 in MDCK cells.

The nonapeptide bradykinin (BK) plays an important role in the production of eicosanoids within the collecting duct of the nephron. We have shown previously that BK can initiate a complex signaling cascade that causes the release of arachidonic acid (AA) from MDCK-D1 cells, a canine cell line of distal tubule and collecting duct origin. This release is dependent upon early activation of specific upstream enzymes, including phosphatidylcholine-specific phospholipase C (PC-PLC) and phospholipase D (PLD).

Role of PLA2, PLC, and PLD in bradykinin-induced release of arachidonic acid in MDCK cells.

The role of cytosolic phospholipase A2 (cPLA2), phosphatidylcholine-specific phospholipase C (PC-PLC) and phospholipase D (PLD) in the bradykinin (BK)-stimulated release of arachidonic acid (AA) was examined in Madin-Darby canine kidney (MDCK) cells. Release of AA, phosphorylcholine, choline, and phosphatidic acid (PA) or the transphosphatidylation product, phosphatidylethanol, was detected after 1 min of BK stimulation. A role for PC-PLC was confirmed with D609, which reduced BK-stimulated AA by 70%.

Regulation of bradykinin-stimulated phospholipase C and arachidonic acid release by protein kinase A in MDCK-D1 cells.

Regulation of phospholipases C (PLC) and arachidonic acid (AA) release by cAMP-dependent protein kinase (PKA) was investigated in MDCK-D1 cells. Bradykinin (BDK) was used to stimulate PLC and AA release, while arginine vasopressin (AVP), forskolin (FSK), isobutylmethylxanthine (IBMX) were used to increase cAMP levels and stimulate PKA. When cells were preincubated for 20 min with 10 microM FSK + 0.

Effect of retinoic acid on Nm/23 nucleoside diphosphate kinase and components of cyclic adenosine monophosphate-dependent signalling in human neuroblastoma cell lines.

The effects of retinoic acid on components of the cAMP-dependent signalling system were examined in two related human neuroblastoma cell lines SK-N-SH-F (SHF) and SK-N-SH-N (SHN). Retinoid treatment for a week significantly increased the concentration of intracellular cAMP and the levels of activity of protein kinase A and adenylate cyclase in both cell lines. Retinoic acid treatment also caused a very marked translocation of nucleoside diphosphate kinase from the cytosol to the membrane fraction.

Vitamin E suppresses diacylglycerol (DAG) level in thrombin-stimulated endothelial cells through an increase of DAG kinase activity.

The present study has examined the role of vitamin E, a natural lipid antioxidant, in the production of diacylglycerol (DAG) and phosphatidic acid (PA) in thrombin-stimulated human endothelial cells. Cells were labelled with [3H]myristate and the incorporation and distribution of [3H]myristate into cellular lipids was not affected by vitamin E. However, in response to thrombin stimulation, considerably more PA and less DAG were formed in cells enriched with vitamin E.

Transfer of arachidonyl groups within the lipids of two human neuroblastoma cell lines.

The incorporation and mobilization of [3H]arachidonic acid in lipids of human neuroblastoma cell lines, SK-N-SHF and LA-N-5, was studied. Essentially similar results were obtained with these two cell lines. Except for phosphatidylinositol which displayed the highest specific activity, the incorporation patterns within phospholipid classes tended to reflect phospholipid composition initially.

Retinoic acid- and staurosporine-induced bidirectional differentiation of human neuroblastoma cell lines.

The differentiation pattern of two related human neuroblastoma cell lines, SK-N-SHF and SK-N-SHN, induced by retinoic acid and staurosporine was studied. Immunohistochemical and electron microscopic examination of the cells indicated that the SHF variant could undergo differentiation along a melanocytic route when treated with retinoic acid and to neuronal cells when treated with retionic acid and staurosporine together. Treatment of SHN cells with either or both these agents caused neuronal differentiation.