Unusual Case of Anuria Due to African Bee Stings

We describe a case of multiple African bee stings in which the exceptionally high dose suggests a direct effect of hymenoptera venom on the renal tubules. The case does not follow the previously reported pattern of hypovolemic or anaphylactic shock, hemolysis and/or rhabdomyolysis, despite the potentially lethal amount of venom injected

Seizures in Dialysis Patients Treated with Recombinant Erythropoietin. Review of the Literature and Guidelines for Prevention

Anemia is one of the major limitations to rehabilitation in patients with end-stage renal disease (ESRD). The efficacy of recombinant human erythropoietin (rHuEPO) in the treatment of renal anemia is well established. Nevertheless, rHuEPO therapy has been associated with serious untoward effects. There appears to be an increased risk of hypertension, not infrequently accompanied by hypertensive encephalopathy and seizures. The mechanism of hypertension remains uncertain. It is associated with an increase in blood viscosity, a reversal of hypoxic vasodilatation, and, possibly, a direct pressor effect of the hormone. Seizures, otherwise, may be the result of cerebral hypoperfusion and, finally, of a focal cerebral edema. The guidelines for rHuEPO treatment and prevention of associated convulsions are outlined. The possible convulsive risk induced by this treatment, even at low doses, particularly in patients with a previous history of seizures, is stressed.

Effect of culture residence time on substrate uptake and storage by a pure culture of Thiothrix (CT3 strain) under continuous or batch feeding

A pure culture of the filamentous bacterium Thiothrix, strain CT3, was aerobically cultured in a chemostat under continuous acetate feeding at three different culture residence times (RT 6, 12 or 22 d) and the same volumetric organic load rate (OLR 0.12gCOD/L/d). Cells cultured at decreasing RT in the chemostat had an increasing transient response to acetate spikes in batch tests. The maximum specific acetate removal rate increased from 25 to 185mgCOD/gCOD/h, corresponding to a 1.8 to 8.1 fold higher respective steady-state rate in the chemostat. The transient response was mainly due to acetate storage in the form of poly(3-hydroxybutyrate) (PHB), whereas no growth response was observed at any RT. Interestingly, even though the storage rate also decreased as the RT increased, the storage yield increased from 0.41 to 0.50 COD/COD. This finding does not support the traditional view that storage plays a more important role as the transient response increases. The transient response of the steady-state cells was much lower than in cells cultured under periodic feeding (at 6 d RT, from 82 to 247mgCOD/gCOD/h), with the latter cells showing both storage and growth responses. On the other hand, even though steady-state cells had no growth response and their storage rate was also less, steady-state cells showed a higher storage yield than cells cultured under dynamic feeding. This suggests that in Thiothrix strain CT3, the growth response is triggered by periodic feeding, whereas the storage response is a constitutive mechanism, independent from previous acclimation to transient conditions.

Study of performances, stability and microbial characterization of a Sequencing Batch Biofilter Granular Reactor working at low recirculation flow

The Sequencing Batch Biofilter Granular Reactor (SBBGR) is a promising wastewater treatment technology characterized by high biomass concentration in the system, good depuration performance and low sludge production. Its main drawback is the high energy consumption required for wastewater recirculation through the reactor bed to ensure both shear stress and oxygen supply. Therefore, the effect of low recirculation flow on the long-term (38 months) performance of a laboratory scale SBBGR was studied. Both the microbial components of the granules, and their main metabolic activities were evaluated (heterotrophic oxidation, nitrification, denitrification, fermentation, sulphate reduction and methanogenesis). The results indicate that despite reduced recirculation, the SBBGR system maintained many of its advantageous characteristics.

High-rate anaerobic treatment of Fischer-Tropsch wastewater in a packed-bed biofilm reactor

This study investigates the anaerobic treatment of an industrial wastewater from a Fischer-Tropsch (FT) process in a continuous-flow packed-bed biofilm reactor operated under mesophilic conditions (35 degrees C). The considered synthetic wastewater has an overall chemical oxygen demand (COD) concentration of around 28g/L, mainly due to alcohols. A gradual increase of the organic load rate (OLR), from 3.4gCOD/L/d up to 20gCOD/L/d, was adopted in order to overcome potential inhibitory effects due to long-chain alcohols (>C6). At the highest applied OLR (i.e., 20gCOD/L/d) and a hydraulic retention time of 1.4d, the COD removal was 96% with nearly complete conversion of the removed COD into methane. By considering a potential of 200tCOD/d to be treated, this would correspond to a net production of electric energy of about 8x10(7)kWh/year. During stable reactor operation, a COD balance and batch tests showed that about 80% of the converted COD was directly metabolized through H(2)(-) and acetate-releasing reactions, which proceeded in close syntrophic cooperation with hydrogenotrophic and acetoclastic methanogenesis (contributing to about 33% and 54% of overall methane production, respectively). Finally, energetic considerations indicated that propionic acid oxidation was the metabolic conversion step most dependent on the syntrophic partnership of hydrogenotrophic methanogens and accordingly the most susceptible to variations of the applied OLR or toxicity effects.

Role of biomass adaptation in the removal of formic acid in sequencing batch reactors

This study deals with formic acid removal in activated sludge processes, in particular in the processes carried out in sequencing batch reactors (SBRs). Formic acid removal has been investigated in a SBR fed with acetic and formic acids at equimolar concentrations. Biomass performance in the reactor has been investigated both by the analysis of the removal of the two substrates and by batch tests. Regarding SBR process, the obtained results show that a relevant difference occurred between formic and acetic acid profiles. Acetic acid was never found in the effluent and was always completely removed during the reaction phase. On the other hand, formic acid removal was determined by biomass acclimation, which is in turn determined by sludge age imposed to the system. Batch tests confirmed that formic acid removal occurs only if biomass is acclimated. It has been shown that the minimal sludge age to obtain complete formic acid removal is much higher than those predictable with the classical models of microbial growth in wastewater treatment processes. The advantages of SBRs over continuous-flow systems in the removal of formic acid have also been highlighted.

Effect of the Length of the Cycle on Biodegradable Polymer Production and Microbial Community Selection in a Sequencing Batch Reactor

The effect of the length of the cycle on the enrichment and selection of mixed cultures in sequencing batch reactors (SBRs) has been studied, with the aim of biodegradable polymers (namely, polyhydroxyalkanoates (PHAs)) production from organic wastes. At a fixed feed concentration (20 gCOD/L) and organic loading rate (20 gCOD/L/day), the SBR was operated at different lengths of the cycle, in the range 1-8 h. Process performance was measured by considering the rates and yields of polymer storage and of the competing phenomenon of growth. The selected biomass was enriched with microorganisms that were able to store PHAs at high rates and yields only when the length of the cycle was 2 or 4 h, even though in these conditions the process was unstable. On the other hand, when the length of the cycle was 1 or 8 h, the dynamic response of the selected microorganisms was dominated by growth. The best process performance was characterized by storage rates in the range 500-600 mgCOD/gCOD/h and storage yields of 0.45-0.55 COD/COD. The corresponding productivity of the process was in the range 0.25-0.30 gPHA/L/h, the highest values obtained until now for mixed cultures. The microbial composition of the selected biomasses was analyzed through denaturing gradient gel electrophoresis (DGGE) and reverse-transcriptase denaturing gradient gel electrophoresis (RT-DGGE). The instability of the runs characterized by high storage rate was associated with a higher microbial heterogeneity compared to the runs with a stable growth response.

Effect of periodic feeding on substrate uptake and storage rates by a pure culture of Thiothrix (CT3 strain)

A pure culture of Thiothrix strain CT3 has been aerobically cultured under periodic acetate feeding in a Sequencing Batch Reactor (SBR) at volumetric organic load rate of 0.12gCODL(-1)d(-1). Two different culture residence times (12d or 20d) were adopted as well as two different feed frequencies (1 and 4d(-1), for each culture residence time), the volumetric organic load rate being the same under all conditions. The transient response of the microorganism to the periodic acetate feed was investigated through batch tests with biomass withdrawn from the SBR, as function of the different SBR operating conditions. In all tested conditions, a quick transient response to the acetate spike was observed with fast increase of acetate uptake rate (ranging from 71 to 247mgCODgCOD(-1)h(-1)). This transient response was mainly due to acetate storage in form of poly-hydroxybutyrate (ranging from 45% to 64% of the observed yield) whereas the growth response (i.e. increase of production rate of active biomass) generally played a minor role (ranging from 21% to 38% of the observed yield). Apart from this general trend, culture residence time as well as feed frequency had a strong impact on transient behaviour of cultured cells. The overall transient response (i.e. maximum specific substrate removal rate) increased as culture residence time decreased or as feed frequency increased. Moreover, the ratio of storage response and growth response increased as the overall transient response decreased, i.e. the storage response was preferentially maintained when cells presented a lower transient response. The ability of the cells to increase their growth rate with respect to SBR average value was the lowest under the most unfavourable conditions (residence time 20d, feed frequency 1d(-1)) and increased with the increase in maximum substrate uptake rate.

Enrichment of activated sludge in a sequencing batch reactor for polyhydroxyalkanoate production

The paper describes the start up of a process for the production of polyhydroxyalkanoates (PHAs) from activated sludge. The excess sludge from a wastewater treatment plant was inoculated in a lab-scale sequencing batch reactor (SBR) to be enriched under aerobic conditions through intermittent feeding with a mixture of organic acids. Enriching of activated sludge was monitored through the measurement of polymer concentrations either in the mixed liquor or in the microbial biomass. The bacterial population dynamics during the SBR start up was followed through denaturing gradient gel electrophoresis and the main species present at the steady state were identified. All the measured parameters significantly changed in the SBR during first two weeks after the inoculum was seeded into the reactor, they then stabilized. At the steady state, the SBR produced 2.6 gVSSl(-1) d(-1), with a PHA content of 11% (on a COD basis). The enriched microbial biomass was then transferred into a batch reactor where the bacterial polymer content was increased through a new feeding. In the final batch stage, maximum storage rate and maximum polymer content in the biomass were 405 mgCOD gCOD(-1) h(-1) and 44% (on a COD basis), respectively. The PHA storage from the enriched microbial biomass was about 20 times faster and the PHA content was about 4 times higher than that of the inoculated activated sludge. Observations by fluorescence microscopy showed that the majority of microorganisms in the enriched biomass could be stored. Among the numerically most representative genera in the enriched biomass, Thauera, Candidatus Meganema perideroedes, and Flavobacterium were identified.

Effect of the applied organic load rate on biodegradable polymer production by mixed microbial cultures in a sequencing batch reactor

This article studies the operation of a new process for the production of biopolymers (polyhydroxyalkanoates, PHAs) at different applied organic load rates (OLRs). The process is based on the aerobic enrichment of activated sludge to obtain mixed cultures able to store PHAs at high rates and yields. A mixture of acetic, lactic, and propionic acids at different concentrations (in the range 8.5-31.25 gCOD/L) was fed every 2 h in a sequencing batch reactor (SBR). The resulting applied OLR was in the range 8.5-31.25 gCOD/L/day. Even though, as expected, the increase in the OLR caused an increase in biomass concentration (up to about 8.7 g COD/L), it also caused a relevant decrease of maximal polymer production rate. This decrease in polymer production rate was related to the different extent of "feast and famine" conditions, as function of the applied OLR and of the start-up conditions. As a consequence the best performance of the process was obtained at an intermediate OLR (20 gCOD/L/day) where both biomass productivity and PHA storage were high enough. However, at this high OLR the process was unstable and sudden decrease of performance was also observed. The sludge characterized by the highest PHA storage response was investigated by 16S rDNA clone library. The clone library contained sequences mostly from PHA producers (e.g., Alcaligenes and Comamonas genera); however many genera and among them, one of the dominant (Thauera), were never described before in relation to PHA storage response.

Biodegradable polymers from organic acids by using activated sludge enriched by aerobic periodic feeding

This article describes a new process for the production of biopolymers (polyhydroxyalkanoates, PHAs) based on the aerobic enrichment of activated sludge to obtain mixed cultures able to store PHAs at high rates and yields. Enrichment was obtained through the selective pressure established by feeding the carbon source in a periodic mode (feast and famine regime) in a sequencing batch reactor. A concentrated mixture of acetic, lactic, and propionic acids (overall concentration of 8.5 gCOD L(-1)) was fed every 2 h at 1 day(-1) overall dilution rate. Even at such high organic load (8.5 gCOD L(-1) day(-1)), the selective pressure due to periodic feeding was effective in obtaining a biomass with a storage ability much higher than activated sludges. The immediate biomass response to substrate excess (as determined thorough short-term batch tests) was characterized by a storage rate and yield of 649 mgPHA (as COD) g biomass (as COD)(-1) h(-1) and 0.45 mgPHA (as COD) mg removed substrates (as COD(-1)), respectively. When the substrate excess was present for more than 2 h (long-term batch tests), the storage rate and yield decreased, whereas growth rate and yield significantly increased due to biomass adaptation. A maximum polymer fraction in the biomass was therefore obtained at about 50% (on COD basis). As for the PHA composition, the copolymer poly(beta-hydroxybutyrate/beta-hydroxyvalerate) with 31% of hydroxyvalerate monomer was produced from the substrate mixture. Comparison of the tests with individual and mixed substrates seemed to indicate that, on removing the substrate mixture for copolymer production, propionic acid was fully utilized to produce propionylCoA, whereas the acetylCoA was fully provided by acetic and lactic acid.

Storage of substrate mixtures by activated sludges under dynamic conditions in anoxic or aerobic environments

In spite of the fact that in most activated sludge plants substrate complex mixtures are removed under alternating anoxic and aerobic conditions, most studies on the dynamic response of biomass are limited to feeding a single substrate (acetate or glucose) under a single redox condition (aerobic or anoxic). In this study, the dynamic response of biomass in a sequencing batch reactor is described in terms of substrate removal and related storage as internal polymers, as functions of single or simultaneous feed of several substrates (acetate, glucose, glutamic acid and ethanol) and of anoxic vs. aerobic conditions. Under anoxic conditions, the four substrates were simultaneously removed at a significantly greater nitrate removal rate than when single substrates were present, so showing that the simultaneous removal was partially due to independent metabolic activities. On the other hand, the removal of every substrate was affected (positively or negatively) by the presence of the others, demonstrating that the substrates can be also used by the same metabolism. As an exception, acetate removal was not affected by the presence of other substrates. As for the comparison of aerobic and anoxic conditions, the acetate uptake rate almost doubled moving from anoxic to aerobic conditions, whereas other substrates were only slightly affected. This difference was probably due to the additional presence of aerobic denitrification, which was much more important for acetate. This also confirmed that acetate removal was independent from other substrates. In all cases, storage was the main mechanism of solids formation, so confirming the general importance of such phenomenon under dynamic conditions, independently from feed complexity and redox conditions.

Removal of molecular weight fractions of COD and phenolic compounds in an integrated treatment of olive oil mill effluents

Previous works (Beccari et al. 1999b; Beccari et al. 2001a; Beccari et al. 2001b) on the anaerobic treatment of olive oil mill effluents (OME) have shown: (a) a pre-treatment based on the addition of Ca(OH)2 and bentonite was able to remove lipids (i.e. the most inhibiting substances present in OME) almost quantitatively; (b) the mixture OME-Ca(OH)2-bentonite, fed to a methanogenic reactor without providing an intermediate phase separation, gave way to high biogas production even at very low dilution ratios; (c) the effluent from the methanogenic reactor still contained significant concentrations of residual phenolic compounds (i.e. the most biorecalcitrant substances present in OME). Consequently, this paper was aimed at evaluating the fate of the phenolic fractions with different molecular weights during the sequence of operations (adsorption on bentonite, methanogenic digestion, activated sludge post-treatment). The results show that a very high percentage (above 80%) of the phenolic fraction below 500 D is removed by the methanogenic process whereas the phenolic fractions above 1,000 D are significantly adsorbed on bentonite; the 8-day activated sludge post-treatment allows an additional removal of about 40% of total filtered phenolic compounds. The complete sequence of treatments was able to remove more than the 96% of the phenolic fraction below 500 D (i.e. the most toxic fraction towards plant germination). Preliminary respirometric tests show low level of inhibition exerted by the effluent from the methanogenic reactor on aerobic activated sludges taken from full-scale municipal wastewater plants.

Enrichment from activated sludges of aerobic mixed cultures capable to degrade vinyl chloride (VC) as the sole carbon source

Two microbial cultures able to degrade high concentrations of VC as the sole carbon source have been obtained by enrichment from activated sludge. The cultures began consuming VC (0.02 mmol l(-1)) only after a long initial acclimation period (1-2 months). After then the concentration of VC was gradually increased (from 0.02 to 0.8 mmol l(-1)) and the cultures were able to maintain VC degrading ability for long time (over 500 days). VC-degrading biomass in the two cultures was characterized by low specific maximum growth rates (0.19-0.21 d(-1)) compared to heterotrophic organisms typically present in activated sludge processes. Monod half-saturation constant was rather low (0.7-1.6 mg VC l(-1)) indicating that it is possible to effectively remove VC to low residual concentrations. The cultures were highly sensitive to even short periods of VC lack (with quick decrease of VC degradation rates) whereas they were not to sudden load increases (up to 3.4 mmol l(-1)). After being cultured with only ethene as the sole carbon and energy source, the cultures kept the ability of degrading VC. Possibility of maintaining the mixed cultures on non-toxic ethene, without loosing VC degradation ability, is very promising for bioaugmentation treatments.

Competitive transport of cadmium and lead through a natural porous medium: influence of the solid/liquid interface processes

Contaminated groundwater typically contains different metal contaminants which may compete with each other for the same adsorption sites. Understanding the fate of these micro-pollutants is of primary importance for the assessment of the risk associated with their dispersion in the environment and for the evaluation of the most appropriate remediation technology. In this regard, column techniques can be considered as useful tools both to perform transport experiments and to obtain equilibrium adsorption data without any perturbation of the actual solid/liquid interface. Cd and Pb monocomponent step column experiments were used to obtain adsorption isotherms on a natural aquifer material. A General Composite approach was used to define the equilibrium adsorption model characterized by two types of sites (ion-exchange and surface complexation sites). Coupling the adsorption model with the Advection-Dispersion equation (by IMPACT code) allowed us to well represent the monocomponent step experiments. The model was successfully used to predict the competitive Cd and Pb transport behaviour. Cd peaks of concentration due to Pb competition were experimentally observed and simulated by the model. This behaviour can be described only by an accurate modelling of the interaction and cannot be predicted by simple isotherms (such as Langmuir or Freundlich type).

Effect of different carbon sources on aerobic storage by activated sludge

A study of substrate removal by real activated sludge with several synthetic substrates (acetate, ethanol, glutamic acid) and wastewater (raw and filtered) was carried out. Substrate, stored compounds (polyhydroxyalkanoates, PHA and internal carbohydrates), ammonia and oxygen uptake rate (OUR) were analytically determined. Polyhydroxybutyrate (PHB) was stored when the substrate was acetate or ethanol, while no appreciable formation of storage compound was detected using glutamic acid. A low amount of PHB was also formed in tests with raw and filtered wastewater which was probably mainly due to its acetate content. As far as the sum of storage and growth (indirectly estimated through ammonia consumption) did not match the overall solids formation, other unidentified mechanisms of substrate removal were likely to occur (biosorption, accumulation and/or storage of unidentified compounds). ASM3 and two derived models were used in the interpretation of experimental data with reference to synthetic substrates. With reference to synthetic substrates ASM3 can well describe the experimental data only assuming a stored product formation much higher than the analytically detected one, whereas the model that assumes a parallel growth and storage on the substrate can well describe the observed stored product profile only assuming a direct contribution of growth much higher than estimated from ammonia consumption. The model that assumes an accumulation/biosorption stage as first step of substrate removal can better describe the whole experimentally observed behaviour. However as well as in ASM3 this implies that some fraction of removed COD is still unidentified. With reference to real wastewater where the different phenomena were mixed up due to the presence of several substrates, the different models gave similar results.

The storage of acetate under anoxic conditions

Till now the role of storage in activated sludge processes under transient conditions has been deeply investigated under anaerobic (EBPR processes) or aerobic (bulking control) environments. Little attention has been given to the role of storage in processes including anoxic environments. Hence, the aim of the present work was to investigate the anoxic storage along with other substrate removal mechanisms under transient conditions. Several mixed culture were ad hoc selected under anoxic environment and periodic feeding (acetate as carbon source) at different organic load rate (OLR) and feed length; then their transient response to substrate spike was investigated by batch tests under both anoxic and aerobic conditions. The relative role of different mechanisms in the substrate removal was established on the basis of COD balance assuming that the acetate COD removed from the liquid phase could be oxidised for energy needs or recovered into solids as poly-3-hydroxybutyric acid (PHB) (storage), other internal precursors or intermediates (accumulation) and active biomass (growth, as estimated by ammonium uptake). In all tested conditions, growth response was very little while PHB storage was prevailing. In some operating conditions, indirect evidence of accumulation (in forms still to be identified) was also found. The transient response was not affected by the presence of free amino acids, at least for the unacclimated mixed culture under observation. Transient response under aerobic condition was quite similar to the anoxic one.

Lead adsorption onto "red soils" as function of environmental conditions

The adsorption characteristics of the "Red Soil" with respect to lead were studied as function of different experimental conditions. Lead adsorption was investigated as function of the complexing capacity of the liquid phase (background electrolyte NaClO4, NaCl, CH3COONa e EDTA), pH (experimental range 4-7) and ionic strength (experimental range 0.001-0.35 M), by determining the adsorption isotherms at the different conditions. Experimental results allowed to identify the presence of different sorption sites, acting on lead removal through different mechanisms (ion exchange and surface complexation). These sorption sites are differently affected by changing the experimental conditions. Adsorption representation in terms of free metal was not able to describe the experimental behaviour, especially when different charged species can be formed and might be sorbed at the surface with different affinities. Particular attention was given to the optimisation of the experimental system based on the flow-through reactor set-up, in order to carry out adsorption tests more representative of the field situation.

Role of storage phenomena on removal of different substrates during pre-denitrification

Removal mechanisms of different substrates during the pre-denitrification step of an anoxic/aerobic sequencing process are studied. Biomass was cultivated in an anoxic/aerobic SBR and fed with a mixture of low and high molecular weight compounds. Substrate removal mechanisms are studied by means of batch tests, performed under anoxic conditions. The dynamic response to a spike of four different substrates (acetate, glucose, glutamic acid and ethanol) is described by simultaneously considering substrate and electron acceptor removal, and PHB and carbohydrates storage. PHB storage is a relevant mechanism during the removal of acetate and ethanol, while glucose is removed mainly by carbohydrate storage.

Enhancement of anaerobic treatability of olive oil mill effluents by addition of Ca(OH)2 and bentonite without intermediate solid/liquid separation

Previous work on the anaerobic treatment of olive oil mill effluents (OME) have shown: (a) lipids, even if more easily degraded than phenols, were potentially capable of inhibiting methanogenesis more strongly; (b) a pretreatment based on addition of Ca(OH)2 and bentonite removed lipids almost quantitatively; (c) preliminary biotreatability tests performed on the pretreated OME showed high bioconversion into methane at very low dilutions ratios, especially when the mixture (OME, Ca(OH)2 and bentonite) was fed to the biological treatment without providing an intermediate phase separation. This paper was directed towards two main aims: (a) to optimize pretreatment: the best results in terms of methane production were obtained by addition of Ca(OH)2 up to pH 6.5 and of 10 g L-1 of bentonite; (b) to evaluate the enhancement of anaerobic treatability of OME pretreated under optimized conditions in a lab-scale continuous methanogenic reactor fed with the substrate without intermediate solid/liquid separation: very satisfactory performances were obtained (at an organic load of 8.2 kg COD m-3 d-1 and at a dilution ratio of 1:1.5 total COD removal was 91%, biogas production was 0.80 g CH4 (as COD)/g tot. COD, lipids removal was 98%, phenols removal was 63%). The results confirm the double role played by bentonite (adsorption of the inhibiting substances and release of the adsorbed biodegradable matter in the methanogenic reactor).

An unusual case of anuria: spontaneous perirenal hematoma in a solitary kidney

A 71-year-old woman with a solitary kidney who developed acute renal failure with anuria secondary to a spontaneous perirenal hematoma is described. Serum creatinine peaked at 335.9 micromol/L and BUN at 26.4 mmol/L, but neither surgery nor dialysis treatment was performed because renal function gradually improved. In this syndrome, first described by Wunderlich in 1856, anuria was not previously reported. Conservative management must always be considered rather than emergency surgery, which usually results in nephrectomy.

Seizures in dialysis patients treated with recombinant erythropoietin. Review of the literature and guidelines for prevention

Anemia is one of the major limitations to rehabilitation in patients with end-stage renal disease (ESRD). The efficacy of recombinant human erythropoietin (rHuEPO) in the treatment of renal anemia is well established. Nevertheless, rHuEPO therapy has been associated with serious untoward effects. There appears to be an increased risk of hypertension, not infrequently accompanied by hypertensive encephalopathy and seizures. The mechanism of hypertension remains uncertain. It is associated with an increase in blood viscosity, a reversal of hypoxic vasodilatation, and possibly, a direct pressor effect of the hormone. Seizures, otherwise, may be the result of cerebral hypoperfusion and, finally, of a focal cerebral edema. The guidelines for rHuEPO treatment and prevention of associated convulsions are outlined. The possible convulsive risk induced by this treatment, even at low doses, particularly in patients with a previous history of seizures, is stressed.

Unusual case of anuria due to African bee stings

We describe a case of multiple African bee stings in which the exceptionally high dose suggests a direct effect of hymenoptera venom on the renal tubules. The case does not follow the previously reported pattern of hypovolemic or anaphylactic shock, hemolysis and/or rhabdomyolysis, despite the potentially lethal amount of venom injected.

Prevalence of hepatitis C virus antibodies in hemodialysis patients in the area of Milan

We studied the seroprevalence of antibodies to hepatitis C virus (HCV Ab) in a cohort of 229 chronic hemodialysis patients followed by 6 Dialysis Units in the Milan area. HCV Ab was present in 51 (22.3%) of 229 examined patients. Previous blood transfusions and surgery did not clearly influence HCV seroconversion, whereas duration of dialysis treatment seems to be strictly related to HCV Ab positivity.