The phototrophic metabolic behaviour of Candidatus accumulibacter.

The phototrophic capability of Candidatus Accumulibacter (Accumulibacter), a common polyphosphate accumulating organism (PAO) in enhanced biological phosphorus removal (EBPR) systems, was investigated in this study. Accumulibacter is phylogenetically related to the purple bacteria Rhodocyclus from the family Rhodocyclaceae, which belongs to the class Betaproteobacteria. Rhodocyclus typically exhibits both chemoheterotrophic and phototrophic growth, however, limited studies have evaluated the phototrophic potential of Accumulibacter. To address this gap, short and extended light cycle tests were conducted using a highly enriched Accumulibacter culture (95%) to evaluate its responses to illumination. Results showed that, after an initial period of adaptation to light conditions (approximately 4-5 h), Accumulibacter exhibited complete phosphorus (P) uptake by utilising polyhydroxyalkanoates (PHA), and additionally by consuming glycogen, which contrasted with its typical aerobic metabolism. Mass, energy, and redox balance analyses demonstrated that Accumulibacter needed to employ phototrophic metabolism to meet its energy requirements. Calculations revealed that the light reactions contributed to the generation of, at least more than 67% of the ATP necessary for P uptake and growth. Extended light tests, spanning 21 days with dark/light cycles, suggested that Accumulibacter generated ATP through light during initial operation, however, it likely reverted to conventional anaerobic/aerobic metabolism under dark/light conditions due to microalgal growth in the mixed culture, contributing to oxygen production. In contrast, extended light tests with an enriched Tetrasphaera culture, lacking phototrophic genes in its genome, clearly demonstrated that phototrophic P uptake did not occur. These findings highlight the adaptive metabolic capabilities of Accumulibacter, enabling it to utilise phototrophic pathways for energy generation during oxygen deprivation, which holds the potential to advance phototrophic-EBPR technology development.

Long term operation of a phototrophic biological nutrient removal system: Impact of CO2 concentration and light exposure on process performance.

The utilization of non-aerated microalgae-bacterial consortia for phototrophic biological nutrient removal (photo-BNR) has emerged as an alternative to conventional wastewater treatment. Photo-BNR systems are operated under transient illumination, with alternating dark-anaerobic, light-aerobic and dark-anoxic conditions. A deep understanding of the impact of operational parameters on the microbial consortium and respective nutrient removal efficiency in photo-BNR systems is required. The present study evaluates, for the first time, the long-term operation (260 days) of a photo-BNR system, fed with a COD:N:P mass ratio of 7.5:1:1, to understand its operational limitations. In particular, different CO2 concentrations in the feed (between 22 and 60 mg C/L of Na2CO3) and variations of light exposure (from 2.75 h to 5.25 h per 8 h cycle) were studied to determine their impact on key parameters, like oxygen production and availability of polyhydroxyalkanoates (PHA), on the performance of anoxic denitrification by polyphosphate accumulating organisms. Results indicate that oxygen production was more dependent on the light availability than on the CO2 concentration. Also, under operational conditions with a COD:Na2CO3 ratio of 8.3 mg COD/mg C and an average light availability of 5.4 ± 1.3 W h/g TSS, no internal PHA limitation was observed, and 95 ± 7%, 92 ± 5% and 86 ± 5% of removal efficiency could be achieved for phosphorus, ammonia and total nitrogen, respectively. 81 ± 1.7% of the ammonia was assimilated into the microbial biomass and 19 ± 1.7% was nitrified, showing that biomass assimilation was the main N removal mechanism taking place in the bioreactor. Overall, the photo-BNR system presented a good settling capacity (SVI ∼60 mL/g TSS) and was able to remove 38 ± 3.3 mg P/L and 33 ± 1.7 mg N/L, highlighting its potential for achieving wastewater treatment without the need of aeration.

Association between perceived stress and health-risk behaviours in workers.

Individuals who experience stress can engage in health-risk behaviours that may decrease work performance. The aim of this study was to determine perceived stress levels in Brazilian workers and verify whether perceived stress was associated with health-risk behaviours. Stress levels of 1,270 workers (1,019 men, 251 women) were assessed using the Perceived Stress Scale. The health-risk behaviours investigated were low intake of vegetables and fruits, daily smoking, high-risk alcohol consumption, physical inactivity, and the presence of obesity. The Student's t-test or one-way analysis of variance was used to assess differences in stress levels. Ordinal regression was used to determine the association between the degrees of stress and health-risk behaviours. Women had higher perceived stress levels than men. In addition, perceived stress levels were higher in those who had low socioeconomic status, were unmarried, had a negative perception of their health, were smokers, or had obesity. Smoking and the presence of two or more health-risk behaviours were associated with 1.84 (95% CI: 1.24-2.73) times and 1.49 (95% CI: 1.18-1.89) times higher odds of experiencing higher degrees of stress, respectively. In women, such an association was observed with the presence of obesity (odds ratio: 2.0; 95% CI: 1.01-3.98).

Achieving nitrogen and phosphorus removal at low C/N ratios without aeration through a novel phototrophic process.

Conventional wastewater treatment technologies for biological nutrient removal (BNR) are highly dependent on aeration for oxygen supply, which represents a major operational cost of the process. Recently, phototrophic enhanced biological phosphorus removal (photo-EBPR) has been suggested as an alternative system for phosphorus removal, based on a consortium of photosynthetic microorganisms and chemotrophic bacteria, eliminating the need for costly aeration. However, wastewater treatment plants must couple nitrogen and phosphorus removal to achieve discharge limits. For this reason, a new microalgae-bacterial based system for phosphorus and nitrogen removal is proposed in this work. The photo-BNR system studied here consists of a sequencing batch reactor operated with dark anaerobic, light aerobic, dark anoxic and idle periods, to allow both N and P removal. Results of the study show that the photo-BNR system was able to remove 100% of the 40 mg N/L of ammonia fed to the reactor and 94 ± 3% of the total nitrogen (Influent COD:N ratio of 300:40, similar to domestic wastewater). Moreover, an average of 25 ± 9.2 mg P/L was simultaneously removed in the photo-BNR tests, representing the P removal capacity of this system, which exceeds the level of P removal required from typical domestic wastewater. Full ammonia removal was achieved during the light phase, with 67 ± 5% of this ammonia being assimilated by the microbial culture and the remaining 33 ± 5% being converted into nitrate. The assimilated P corresponded to 2.8 ± 0.23 mg P/L, which only represented, approximately, 1/9 of the P removal capacity of the system. Half of the nitrified ammonia was subsequently denitrified during the dark anoxic phase (50 ± 24%). Overall, the photo-BNR system represents the first treatment alternative for N and P from domestic wastewater with no need of mechanical aeration or supplemental carbon addition, representing an alternative low-energy technology of interest.

Biomechanical and biochemical investigation of erythrocytes in late stage human leptospirosis.

Leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira, which can cause lipid changes in the erythrocyte membrane. Optical tweezers were used to characterize rheological changes in erythrocytes from patients with leptospirosis in the late stage. Biochemical methods were also used for quantification of plasma lipid, erythrocyte membrane lipid, and evaluation of liver function. Our data showed that the mean elastic constant of erythrocytes from patients with leptospirosis was around 67% higher than the control (healthy individuals), indicating that patient's erythrocytes were less elastic. In individuals with leptospirosis, several alterations in relation to control were observed in the plasma lipids, however, in the erythrocyte membrane, only phosphatidylcholine showed a significant difference compared to control, increasing around 41%. With respect to the evaluation of liver function of individuals with leptospirosis, there was a significant increase in levels of alanine transaminase (154%) and aspartate transaminase (150%), whereas albumin was 43.8% lower than control (P<0.01). The lecithin-cholesterol acyltransferase fractional activity was 3.6 times lower in individuals with leptospirosis than in the healthy individuals (P<0.01). The decrease of the erythrocyte elasticity may be related to the changes of erythrocyte membrane phospholipids composition caused by disturbances that occur during human leptospirosis, with phosphatidylcholine being a strong candidate in the erythrocyte rheological changes.

Biomechanical and biochemical investigation of erythrocytes in late stage human leptospirosis

Leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira, which can cause lipid changes in the erythrocyte membrane. Optical tweezers were used to characterize rheological changes in erythrocytes from patients with leptospirosis in the late stage. Biochemical methods were also used for quantification of plasma lipid, erythrocyte membrane lipid, and evaluation of liver function. Our data showed that the mean elastic constant of erythrocytes from patients with leptospirosis was around 67% higher than the control (healthy individuals), indicating that patient's erythrocytes were less elastic. In individuals with leptospirosis, several alterations in relation to control were observed in the plasma lipids, however, in the erythrocyte membrane, only phosphatidylcholine showed a significant difference compared to control, increasing around 41%. With respect to the evaluation of liver function of individuals with leptospirosis, there was a significant increase in levels of alanine transaminase (154%) and aspartate transaminase (150%), whereas albumin was 43.8% lower than control (P<0.01). The lecithin-cholesterol acyltransferase fractional activity was 3.6 times lower in individuals with leptospirosis than in the healthy individuals (P<0.01). The decrease of the erythrocyte elasticity may be related to the changes of erythrocyte membrane phospholipids composition caused by disturbances that occur during human leptospirosis, with phosphatidylcholine being a strong candidate in the erythrocyte rheological changes.

The effect of seed sludge on the selection of a photo-EBPR system.

The phototrophic-enhanced biological phosphorus removal system (photo-EBPR) was recently proposed as an alternative photosynthetic process to conventional phosphorus removal. Previous work showed the possibility of obtaining a photo-EBPR system starting from a culture already enriched in polyphosphate accumulating organisms (PAOs). The present work evaluated whether the same could be achieved starting from conventional activated sludge. A sequencing batch reactor inoculated with sludge from a wastewater treatment plant (WWTP) was fed with a mixture of acetate and propionate (75%:25%) and subjected to dark/light cycles to select a photo-EBPR system containing PAOs and photosynthetic organisms, the oxygen providers for the system. The results showed that it is possible to obtain a photo-EBPR system starting from a WWTP sludge, although the process is slower than when started with a sludge already enriched in PAOs. After 15 days of operation, the system could remove 60 ± 2 mg-P/L of phosphorus (approximately 67% of the concentration at the end of dark period) in the light period, from which 13 ± 1 mg-P/L was removed during the phase without external air supply. These results indicate that a photo-EBPR system can be obtained independently of the seed sludge initially used, provided that a suitable operating strategy is implemented, i.e. by imposing conditions that favour the growth and coexistence of PAOs and photosynthetic microorganisms.

The impact of operational strategies on the performance of a photo-EBPR system.

A novel Phototrophic - Enhanced Biological Phosphorus Removal (Photo-EBPR) system, consisting of a consortium of photosynthetic organisms and polyphosphate accumulating organisms (PAOs), was studied in this work. A sequencing batch reactor was fed with a mixture of acetate and propionate (75%-25%) and subjected to dark/light cycles in order to select a photo-EBPR system containing PAOs and photosynthetic organisms, the latter likely providers of oxygen to the system. The results from the selection period (stage 1) showed that the photo-EBPR culture was capable of performing P release in the dark and P uptake in the presence of light, under limited oxygen concentrations. During the optimization period, the aeration period, which was initially provided at the end of the light phase, was gradually reduced until a non-aerated system was achieved, while the light intensity was increased. After optimization of the operational conditions, the selected consortium of photosynthetic organisms/PAOs showed high capacity of P removal in the light phase in the absence of air or other electron acceptor. A net P removal of 34 ± 3 mg-P/L was achieved, with a volumetric P removal rate of 15 ± 2 mg-P/L.h, and 79 ± 8% of P removal from the system. Also, in limiting oxygen conditions, the P uptake rate was independent of the PHA consumption, which demonstrates that the organisms obtained energy for P removal from light. These results indicated that a photo-EBPR system can be a potential solution for P removal with low COD/P ratios and in the absence of air, prospecting the use of natural sunlight as illumination, which would reduce the costs of EBPR operation regarding aeration.

[Microbiology of diabetic foot infections: role of ertapenem]. / Microbiologia das infecções no pé diabético: o papel do ertapenem.

Many patients with diabetes develop foot ulcers that are very susceptible to infections which may place the patients at risk for lower-limb amputation. Such infections require adequate management with antibiotics. The authors performed a systematic analysis and critical review of studies with the dual aim of assessing bacterial profiles and antimicrobial susceptibility patterns in patients with diabetic foot infections using various methods for sample collection and evaluating the safety and efficacy of ertapenem as initial empirical treatment for such infections. Following a selection of only studies with adequate description of methods for pathogen isolation and antibiogram determination, nine studies were included. The need for adequate prospective multicenter studies to assess the value of empirical antibiotic regimens for diabetic foot became evident and the conclusions were as follows: proper identification of causative agents, appropriate antibiotic therapy and management of complications in these infections are essential to achieve a successful outcome; the sampling procedure is extremely important in the evaluation of the microbial flora of the foot ulcer; susceptibility testing should be performed routinely at least for those species with unpredictable resistance; and ertapenem has been shown to be useful in the treatment of a wide range of moderate-to-severe lower extremity infections in a broad spectrum of patients.

Experimental hypothyroidism during pregnancy affects nociception and locomotor performance of offspring in rats.

BACKGROUND: Thyroid hormones (THs) play a crucial role in the development of several organic systems. An adequate support of maternal THs may be required to ensure a normal nociceptive function of offspring into adulthood. We investigated the impact of experimental gestational hypothyroidism (EGH) on nociceptive threshold and motor performance in the offspring at different post-natal days (PND) in both male and female rats. METHODS: EGH was induced by the administration of 0.02% methimazole (MMI) in the drinking water from the ninth day of gestation until birth. The offspring from MMI-treated dams (OMTDs) or from water-treated dams (OWTDs) were assessed for thermal and mechanical nociception using the tail-flick test and von Frey filaments, respectively. Both rota-rod and grip strength were used to assess motor function. RESULTS: OMTD had reduced thermal (p<0.05) but not mechanical threshold at all studied ages (60 and 120 PND). Sixty-day-old OMTD presented reduced latency to the tail-flick test (p=0.01). Grip strength in 120-day-old OMTD was reduced (p<0.01). However, only male OMTD presented a lower locomotor performance on the rota-rod test when analysed on the 60th PND (p<0.01). CONCLUSIONS: EGH promotes hypersensitivity to noxious thermal but not mechanical stimulus. Moreover, motor force is similarly reduced in male and female OMTDs, whereas motor performance is reduced only in mature male OMTD, suggesting the presence of a protective factor in females.

Estimation of the number and size of human flexor digiti minimi muscle motor units using histological methods.

Motor unit (MU) number and size estimates were obtained from the human flexor digiti minimi muscle using histological methods. Ten adult fresh cadavers (33-74 years old) were used. The number of MUs was 130 +/- 15 and the MU size was 108 +/- 10. These values are similar to those reported for other hypothenar muscles, using the same criteria. The results here described are in best agreement with those reported by the incremental and automated incremental methods.

Nerve cell loss in the myenteric plexus of the human esophagus in relation to age: a preliminary investigation.

Morphometric measurements have been carried out on the human myenteric esophageal neurons at the ages of 20-40 and more than 70 years. The number of neurons decreases after 70 years of age, which is accompanied by an increase in the sizes of the neurons. In percentage terms the decrease in the number of neurons in the aged varied from 22 to 62% along the esophagus being most pronounced in its superior third at the junction with the pharynx.

Influence of hypoxanthine and other purines on the lecithin:cholesterol acyltransferase reaction in the plasma of rat and other species.

1. Esterification of radiolabelled cholesterol in the plasma of rat, mouse, pig, ox and, to a lesser extent, guinea pig was partially inhibited by hypoxanthine, xanthine and guanine; esterification in human plasma and in plasma from 12 other vertebrate species was unaffected by purines. 2. Esterification of endogenous cholesterol and the formation of lysolecithin in rat plasma were decreased in the presence of purines indicating that it was the lecithin:cholesterol acyltransferase (LCAT) reaction that was inhibited rather than the isotopic equilibration of labelled cholesterol with the endogenous substrate lipoproteins. 3. Maximum inhibition of the LCAT reaction in rat plasma occurred at 1.4 mM hypoxanthine or xanthine; inhibition was not dependent upon the concentration of LCAT or plasma lipoproteins but increased with the amount of lipoprotein depleted rat plasma (LDRP) present in the incubation mixture. 4. Partial inhibition of the LCAT reaction in rat or mouse plasma by purines had no significant effect on the fatty acyl composition of the cholesteryl esters (CE) formed by LCAT. 5. In the presence of heated rat plasma, LDRP or, to a lesser extent, rat high density lipoproteins (HDL) prepared from heated plasma, the LCAT reaction in human plasma was inhibited by hypoxanthine. 6. Rat HDL and LDRP prepared from plasma pre-incubated at 37 degrees C for 4 hr before heating increased and decreased, respectively, the inhibitory effect of hypoxanthine on human plasma LCAT compared with HDL and LDRP prepared from unincubated rat plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations in the levels and lipid composition of plasma lipoproteins (VLDL, LDL and HDL) in Brazilian patients with hepatosplenic schistosomiasis mansoni.

1. The plasma concentrations of low- and high-density lipoproteins (LDL and HDL) were significantly reduced in Brazilian patients with compensated hepatosplenic schistosomiasis mansoni (SM) when compared with healthy individuals, but very low-density lipoprotein (VLDL) levels were unchanged. 2. All three classes of lipoproteins isolated from SM plasma had an increased content of triacylglycerol and unesterified cholesterol and decreased cholesteryl ester and phospholipid. 3. The individual phospholipid composition of patient VLDL, LDL, HDL was also altered; the amount of phosphatidylcholine was increased and that of lysophosphatidylcholine decreased. 4. The saturated and monounsaturated fatty acyl content of cholesteryl esters in patient lipoproteins was also significantly increased, and diunsaturated and polyunsaturated fatty acyl content was decreased. 5. When isolated lipoproteins were examined as negatively stained preparations by electron microscopy, the morphology of SM patient LDL was normal but the HDL fraction was abnormal and showed marked heterogeneity of size with the presence of occasional discoidal particles which resembled "nascent" HDL.

Alterations in the levels and lipid composition of plasma lipoproteins (VLDL, LDL and HDL) in Brazilian patients with hepatosplenic schistosomiasis mansoni

1. The plasma concentrations of low- and high-density lipoproteins (LDL and HDL) were significantly reduced in Brazilian patients with compensated hepatosplenic schistosomiasis mansoni (SM) when compared with healthy individuals, but very low-density lipoprotein (VLDL) levels were unchanged. 2. All three classes of lipoproteins isolated from SM plasma had an increased content of triacylglycerol and unesterified cholesterol and decreased cholesteryl ester and phospholipid. 3. The individual phospholipid composition of patient VLDL, LDL, HDL was also altered; the amount of phosphatidylcholine was increased and that of lysophosphatidylcholine decreased. 4. The saturated and monounsaturated fatty acyl content of cholesteryl esters in patient lipoproteins was also significantly increased, and diunsaturated and polyunsaturated fatty acyl content was decreased. 5. When isolated lipoproteins were examined as negatively stained preparations by electron microscopy, the morphology of SM patient LDL was normal but the HDL fraction was abnormal and showed marked heterogeneity of size with the presence of occasional discoidal particles which resembled nascent HDL

Alterations in the fatty acyl composition of plasma cholesteryl esters in Brazilian patients with hepatosplenic schistosomiasis mansoni.

1. The dyslipoproteinemia commonly occurring in the hepatosplenic forms of schistosomiasis mansoni in Brazilian patients is characterized by low plasma levels of cholesteryl esters and of the cholesterol-esterifying enzyme, lecithin:cholesterol acyltransferase (LCATase, EC.2.3.1.43). 2. In the present study, normal healthy individuals and patients suffering from hepatosplenic schistosomiasis mansoni were compared for the fatty acyl compositions of circulating plasma cholesteryl esters and of those formed in vitro by the action of LCATase on a) the endogenous plasma lipoproteins and b) an excess of lipoprotein substrate composed of heat-inactivated plasma. 3. In patient plasma the proportions of saturated and monounsaturated cholesteryl esters were higher and those of diunsaturated and polyunsaturated esters were lower than in the control group. 4. Similar differences were observed between patients and controls in the proportions of the cholesteryl ester subclasses formed in vitro by the action of LCATase on endogenous plasma lipoproteins. 5. Incubation of fresh normal or patient plasma with excess heat-inactivated plasma as substrate for LCATase produced proportions of cholesteryl ester subclasses similar to those formed during incubation of nonheated aliquots of the appropriate substrate plasma. 6. We conclude that the alterations in fatty acyl composition of plasma cholesteryl esters in patients with hepatosplenic schistosomiasis mansoni do not appear to be a direct consequence of the low levels of LCATase activity in patient plasma.

Non-metric cranial variants in Brazilian skulls.

The incidence of 27 non-metric cranial variants is studied in a sample of 124 skulls from Brazil. The unilateral and bilateral frequencies of the variants are determined. The Brazilian population sample was compared with 28 population samples from different parts of the world.

Alterations in the fatty acyl composition of plasma cholesteryl esters in brazilian patients with hepatosplenic schistosomiasis mansoni

1. The dyslipoproteinemia commonly occurring in the hepatosplenic forms of schistosomiais mansoni in Brazilian patients is characterized by low plasma levels of choleteryl esters and of the cholesterol-esterifying enzyme, lecithin:cholesterol acyltransferase (LCATase, EC.2.3.1.43). 2. In the present study, normal helathy individual and patients sufferin from hepatosplenic schistosomiasis mansoni were comapred for the fatty acyl compositons of circulating plasma cholesteryl esters and of those formed in vitro by the action of LCATase on a) the endogenous plasma lipoprotins and b) an excess of lipoprotein substrate composed of heat-inactivated plasma. 3. In patient palsma the proportions of saturated and monounsaturated cholesteryl esters were higher and those of diunsaturated and polyunsaturated esters were lower than in the control group. 4. Similar differences were observed between patients and controls in the proportions of the cholesteryl ester subclasses formed in vitro by the action of LCATase on endogenous plasma lipoprotins. 5. Incubation of fresh normal or patient plasma with escess heat-inactivated plasma as substrate for LCATase produced proportions of cholesteryl ester subclasses similar to those formed dduring incubation of nonheated aliquots of the appropriate plasma. 6. We conclude that the alterations in fatty acyl composition of palsma cholesteryl estes in patients with hepatosplenic schistosomiasis mansoni do not appear to be direct consequence of the low levels of LCATase acivity in patient plasma

Motor units and functional anatomy of the human musculus opponens digiti minimi.

The present anatomical investigation showed that, in 4 musculus opponens digiti minimi beings studied, we found an average value of 158 motor units and 100 muscle fibres per motor unit. These data are in accordance with the execution of the complex action of the m. opponens as an articular stabilizer.

Study of motor units of M. pectineus of the dog (Canis familiaris).

Cross sections of M. pectineus of 6 adult dogs were used to study the number of motor units. Our results revealed that M. pectineus possesses 29,451 muscle fibres and 165 large nerve fibres. Since 60% of these latter fibres are motor fibres, the number of fibres per motor unit of M. pectineus is 294. This fact suggests that this muscle executes finely adjusted movements.