Short and long-term experiments on the effect of sulphide on microalgae cultivation in tertiary sewage treatment

Microalgae cultivation appears to be a promising technology for treating nutrient-rich effluents from anaerobic membrane bioreactors, as microalgae are able to consume nutrients from sewage without an organic carbon source, although the sulphide formed during the anaerobic treatment does have negative effects on microalgae growth. Short and long-term experiments were carried out on the effects of sulphide on a mixed microalgae culture. The short-term experiments showed that the oxygen production rate (OPR) dropped as sulphide concentration increased: a concentration of 5mgSL^-1 reduced OPR by 43%, while a concentration of 50mgSL^-1 came close to completely inhibiting microalgae growth. The long-term experiments revealed that the presence of sulphide in the influent had inhibitory effects at sulphide concentrations above 20mgSL^-1 in the culture, but not at concentrations below 5mgSL^-1. These conditions favoured Chlorella growth over that of Scenedesmus.

Influence of total solids concentration on membrane permeability in a submerged hollow-fibre anaerobic membrane bioreactor

The main aim of this work was to study the influence of the mixed liquor total solids (MLTS) concentration on membrane permeability (K(20)) in a submerged anaerobic membrane bioreactor (SAnMBR) pilot plant, which is equipped with industrial hollow-fibre membranes and treats urban wastewater. This pilot plant was operated at 33 °C and 70 days of SRT. Two different transmembrane fluxes (13.3 and 10 LMH) were tested with a gas sparging intensity of 0.23 Nm(3) m(-2)h(-1) (measured as Specific Gas Demand referred to membrane area). A linear dependence of K(20) on MLTS concentration was observed within a range of MLTS concentration from 13 to 32 g L(-1) and J(20) of 10 LMH. K(20) was maintained at sustainable values (about 100 LMH bar(-1)) even at high MLTS concentrations (up to 20 g L(-1)). In addition, several short-tests were carried out when the membranes were operated at high MLTS concentrations in order to assess the effect of the physical cleaning strategies (relaxation and back-flush) on membrane performance. It was observed that, with the applied gas sparging intensity, the duration of the relaxation stage did not critically affect the membrane performance. On the other hand, the required back-flush frequency was considerably affected by the MLTS concentration.

Experimental study of the anaerobic urban wastewater treatment in a submerged hollow-fibre membrane bioreactor at pilot scale

The aim of this study was to assess the effect of several operational variables on both biological and separation process performance in a submerged anaerobic membrane bioreactor pilot plant that treats urban wastewater. The pilot plant is equipped with two industrial hollow-fibre ultrafiltration membrane modules (PURON® Koch Membrane Systems, 30 m² of filtration surface each). It was operated under mesophilic conditions (at 33 °C), 70 days of SRT, and variable HRT ranging from 20 to 6h. The effects of the influent COD/SO₄-S ratio (ranging from 2 to 12) and the MLTS concentration (ranging from 6 to 22 g L⁻¹) were also analysed. The main performance results were about 87% of COD removal, effluent VFA below 20 mg L⁻¹ and biogas methane concentrations over 55% v/v. Methane yield was strongly affected by the influent COD/SO₄-S ratio. No irreversible fouling problems were detected, even for MLTS concentrations above 22 g L⁻¹.

[Treatment with recombinant interferon alfa-2b of a patient with chronic hepatitis C and concomitant ulcerative colitis]

The case of a patient ulcerative colitis involving an autoimmune base who was treated with recombinant alpha-2b interferon for presenting chronic active hepatitis in relation to virus C is reported. Such treatment was achieved in addition to improving the hepatic disease normalizing the transaminases control the outbreak of ulcerative colitis that the patient was presenting from some days before beginning the treatment. Various aspects are discussed related to the autoimmunity in the ulcerative colitis and in the chronic C hepatitis and the exarcebation of autoimmune phenomena which may lead to interferon therapeutic. As a basis for the above and the review of the literature, we concluded that the existence of ulcerative colitis does not contraindicate the use of alpha-2b interferon in patient with chronic hepatitis, although special control of the disease should be carried out during the treatment period.

Bacteremia following liver biopsy in transplant recipients with Roux-en-Y choledochojejunostomy

Between 1990 and 1995, 666 percutaneous liver biopsies were performed in 196 patients at Gregorio Marañón General Hospital (mean 3.4 biopsies/patient); 533 biopsies (80.03%) were carried out in patients with choledochostomy biliary anastomosis and 133 (19.97%) in patients with choledochojejunostomy. Infectious complications, in the form of sepsis, occurred in two patients, who recovered favorably with antibiotic therapy. These two patients had undergone Roux-en-Y choledochojejunostomy (1.5%, not significant). Our findings suggest that the incidence of infectious complications after liver biopsy in transplant recipients is very low. Antibiotic prophylaxis at the time of liver biopsy in patients with Roux-en-Y choledochojejunostomy may decrease the frequency of infectious complications.

Role of renal prostaglandins in the action of ramipril (HOE-498) in normotensive rats

Changes in blood pressure, plasma renin activity, urine volume, urinary PGE2, 6-keto-PGF1 alpha and kinins, were studied after the administration of the angiotensin converting enzyme inhibitor ramipril (100 mu/kg/day), for one week in concomitantly indomethacin (1 mg/kg/day) treated and untreated rats. Measurements were made basally, before Ramipril administration and on days 1 and 7 during the treatment. Ramipril given alone induced a decrease in urinary PGE2 (NS) and 6-keto-PGF1 alpha (p less than 0.05) on day 1, together with an increase in urinary kinins on day 7 (p less than 0.01) and in urine volume on days 1 and 7 (p less than 0.05). Increased urinary PGE2 (NS) and 6-keto-PGF1 alpha (p less than 0.05) were observed in indomethacin pretreated rats after ramipril administration. No modifications in BP levels were observed either with indomethacin or with ramipril given alone or with ramipril plus indomethacin. Ramipril increased plasma renin activity levels both in indomethacin treated and untreated rats on days 1 (p less than 0.01) and 7 (p less than 0.05). The diuretic effect of ramipril and the stimulation of kinins were blunted when concomitant indomethacin was administered. Although a stimulatory effect of ramipril on urinary PGS was only observed during indomethacin administration, the present results would suggest that a non-inhibited PGS synthesis would be required for the renal actions of Ramipril.

Different excretion pattern of urinary PGE2 and 6-keto-PGF1 alpha in two kidney-one clip Goldblatt rats

Changes in blood pressure and 24 hour urinary excretion of PGE2 and 6-keto-PGF1 alpha have been studied during ten weeks after renal artery clipping or sham operation in rats. From the second week on, systolic blood pressure was significantly increased in the two kidney-one clip rats as compared to controls. Maximal differences were reached in the 10th week after the operation (145 +/- 8 vs 116 +/- 3.2 mm Hg; p less than 0.001). Urinary PGE2 levels showed markedly elevated values versus controls from the 6th week on (p less than 0.001). However, no significant changes in urinary 6-keto-PGF1 alpha excretion were observed between the groups during the whole experimental period. These findings suggest that renal PGE2 may be involved in the pathophysiology of blood pressure control in the two kidney-one clip model, whereas, 6-keto-PGF1 alpha seems not to be altered after renal artery clipping.

Effect of ZK 36 374 on blood pressure, diuresis, plasma renin activity and urinary excretion of prostaglandin E2 and sodium

ZK 36 374 is a chemically stable prostacyclin analogue which has been demonstrated to be a potent vasodilator. The effects of the drug on blood pressure, plasma renin activity, diuresis and urinary excretion of prostaglandin E2 and sodium, were studied on the 1st and 7th days of treatment and a week after the end of the administration to rats submitted to the following experimental situations: Goldblatt 2k-1c, Goldblatt 2k-1c + 5% NaCl loading, 5% NaCl loading, and controls. ZK 36 374 was continuously administered during one week by an osmotic pump subcutaneously implanted and connected to the right jugular vein. Twenty four hours after the pump implantation, blood pressure decreased in the three experimental groups. At the 7th day, pressure remained at similar levels except in NaCl loaded rats where an increase was observed. At the 15th day pressure levels returned to pretreatment values. On the 7th day of treatment urinary PGE2 showed higher values than pretreatment ones, to return to pretreatment at the 15 day. Sodium excretion showed an increase on the 7th day and was even higher on the 15th day. Plasma renin activity levels remained unchanged during the treatment except in the Goldblatt 2k-1c group which showed a significant fall at the 7th day. All the changes described on the 1st day of treatment might be related to counteraction of the blood pressure decrease on the same day.

Simple radioimmunological method for urinary 6-keto-PGF1 alpha measurement

A radioimmunoassay for the determination of 6-keto-PGF1 alpha (stable metabolite of Prostacyclin) in urine using a specific antiserum, is described. The antibody used, showed no significant cross-reactivity with other PGS. (3H)-6-keto-PGF1 alpha has been used as tracer and a 30% Hydroxyapatite suspension was utilized for the separation of bound and free fractions. Standard curve ranges between 2 and 1000 pg thus allowing measurements in urine. Aliquots of 0.2 to 1 ml of 24 hours urinary samples were submitted to a preextraction step with Hexane in order to eliminate neutral fats. After acidifying with 0.1 N HCl to pH = 3.5-4, an Ethyl Ether extraction step was performed showing a recovery of 66%. Repeated analysis of a rat urine pool, showed 7.7 intraassay and 9.8 interassay variation coefficients. Values obtained amounted to 38.3 +/- 4.6 ng/24 h in normal rats and 133 +/- 32 ng/24 h in 5% NaCl loaded rats (p less than 0.001). The values obtained in healthy men were 508 +/- 94 ng/24 h and in women 375 +/- 136 (p less than 0.05).

A radioimmunoassay method for measurement of urinary kinins

A sensitive and specific radioimmunoassay for measuring urinary kinins was developed. Antibodies against bradykinin were induced in rabbits by injecting bradykinin coupled to bovine albumin. One of the antisera generated was used at a final dilution of 1:18,000 to obtain a 30% total binding of bradykinin-(8-tyrosine)-[125I]-triacetate. Synthetic bradykinin (5-1,000 pg) was used as standard in the curves. The sensitivity of the assay was 5 pg. The recovery of bradykinin added to urinary samples was 86.85 +/- 6%. The intraassay and interassay coefficients of variation were 3.3% (n = 12) and 4.4% (n = 5), respectively. The antiserum showed no cross-reactivity with oxytocin or low molecular weight kininogen and cross-reacted with kallidin (lys-bradykinin), met-kallidin, and angiotensin I, but cross-reaction with angiotensin I (2.5%) was low enough to be disregarded. The mean urinary levels of total kinins in 12 normal subjects were 23.2 +/- (SEM) 2.2 micrograms/day.