Impact of chemical oxidation on sludge properties and membrane flux in membrane separation bioreactors

The effects of sodium hypochlorite (NaOCl) on sludge properties and membrane permeate flux were studied using a pressurized stirred ultrafiltration cell. Oxidation with NaOCl resulted in sludge solubilization and decreased sludge floc sizes. The sludge dissolution constant was estimated at 0.3 ± 0.1 mg sludge mg^?1 free chlorine under testing conditions. The increases in soluble chemical oxygen demand and total carbohydrate concentration in centrifuged supernatant were less than proportional to chemical dosage. Membrane permeate fluxes were much lower as a result of oxidation. Soluble biopolymers accounted for more than 76% of the total hydraulic resistance during ultrafiltration of oxidized sludge. By contrast, both the settleable sludge flocs and the soluble biopolymers were important contributors to the hydraulic resistance of sludge before oxidation. Given the benefits of NaOCl solution for membrane cleaning and its negative impact on sludge properties, the quantity of NaOCl solution used for maintenance cleaning of membranes should be optimized. Copyright © 2004 Society of Chemical Industry     

Usefulness of BTA Stat test (Bard) in the diagnosis of bladder cancer. Preliminary results and comparison with cytology and cystoscopy]

Risk factors associated with surgical infections are related to many events that modulate the immune system and affect the surgical procedure. The aim of this study was to determine the influence of low CD4+ lymphocyte counts in 24 patients with human immunodeficiency virus (HIV) undergoing abdominal surgery. Blood samples were obtained, and the lymphocyte population was evaluated perioperatively, as was the nutritional status of the patient. All the patients received selective antibiotic prophylaxis depending on the surgical procedure performed: (1) clean surgery: splenectomies (n = 8); (2) clean-contaminated: cholecystectomy and biliary tract surgery (n = 8); and (3) contaminated: appendectomy (n = 8). Depending on their CD4 count, two groups were formed: one with 200 to 500 cells/ml (n = 11) and the other with < 200 cells/ml (n = 13). When surgical infection was suspected, surgical drainage and microbiologic cultures were undertaken. For statistical evaluation of the groups ANOVA and the chi-square test were used; p < 0.05 was considered significant. Altogether 14 patients (58.3%) had a wound infection, and the mean (+/- SD) CD4 count in those patients was decreased (221.7 +/- 75.1) compared with that of the 10 patients in the uneventful group (386 +/- 81.2). Surgical infection rates were 50% for clean procedures, 62.5% for clean-contaminated procedures, and 62.5% for contaminated surgery. The group of patients with CD4 counts of < 200 cell/ml had an increased incidence of surgical infection, regardless of the type of surgery (p = 0.002). Thus the surgical infection rates with HIV patients undergoing abdominal surgery are dramatically increased. The CD4 and subsequently depressed neutrophil populations increase the risk of surgical infection during major procedures regardless of the type of surgery performed.     

The function of the p190 Rho GTPase-activating protein is controlled by its N-terminal GTP binding domain

p190 is a GTPase-activating protein (GAP) for the Rho family of GTPases. The GAP domain of p190 is at the C terminus of the protein. At its N terminus, p190 contains a GTP binding domain of unknown significance. We have introduced a mutation (Ser36 --> Asn) into this domain of p190 that decreased its ability to bind guanine nucleotide when expressed as a hemagglutinin (HA)-tagged protein in COS cells. In vitro, both the wild type and S36N mutant HA-p190 proteins showed similar GAP activities toward RhoA, but when expressed in NIH 3T3 fibroblasts only wild type p190 appeared able to function as a RhoGAP. Wild type HA-p190 induced a phenotype of rounded cells with long, beaded extensions similar to that seen when Rho function is disrupted by ADP-ribosylation. HA-p190(S36N), although expressed at a similar level to the wild type protein, had no discernible effect on the cells. The beaded extension phenotype induced by wild type HA-p190 required GAP function. A GAP-defective mutant, p190(R1283A), had no effect on cell morphology. Moreover, the beaded extension phenotype could be suppressed by co-expression of a gain-of-function Rho mutant, RhoA(G14V), or Rac mutant, Rac1(G12V). Activation of the Jun kinase (JNK) via muscarinic receptors was inhibited by wild type HA-p190, but JNK activity was enhanced by the S36N mutant. Co-expression of HA-p190 with a fragment containing only the mutated GTP binding domain partially inhibited the beaded extension phenotype, suggesting that it may sequester a factor required for p190 function. Taken together these data demonstrate that within the cell, the Rho/Rac GAP activity of p190 can be regulated by the N-terminal GTP binding domain.     

Electrically induced blink reflex in horses

The electrically induced blink reflex was studied electromyographically in 21 healthy adult, detomidine-sedated horses. Using surface electrodes, the supraorbital nerve was electrically stimulated at the supraorbital foramen. The responses were recorded from the ipsilateral and contralateral orbicularis oculi muscles with concentric needle electrodes inserted in the lateral aspect of the ventral eyelids. Ipsilateral and contralateral recordings were made on successive stimulations of the same side of the face, maintaining a constant stimulus intensity. The electromyographically recorded responses consisted of an early R1 response in the orbicularis oculi muscle ipsilateral to the side of stimulation, a bilateral late response (ipsilateral R2 and contralateral Rc) and a third, R3 response, in the ipsilateral orbicularis oculi muscle. All the responses were polyphasic muscle potentials of variable duration and peak to peak amplitudes. The reflex latency of the R1 response was, as in man, fairly stable. The R2 response showed greater variability both within and between individual horses. The Rc response was recorded in only 13 of the 21 horses and showed a slightly longer latency than the corresponding R2. The R3 response, which is significantly related to pain sensation in man, appeared in 19 horses and showed the greatest variability in latency.     

The use micro-polarization in spinal cord lesions

Transdermal micropolarization of the spinal cord was made in patients with consequences of the spinal cord injury or tuberculous spondylitis. Changes in clinical and electrophysiologic status were evaluated. It was found that local direct current through dermal electrodes promotes an improvement of both motor and autonomic functions in such patients. This corresponded to a positive dynamics both of the spinal cord state and cardiac activity. Possible mechanisms of influence of the direct current on the spinal cord as well as perspectives of application of micropolarization in spinal cord's damage are outlined.