Olfactory discrimination predicts cognitive decline among community-dwelling older adults

The presence of olfactory dysfunction in individuals at higher risk of Alzheimer's disease has significant diagnostic and screening implications for preventive and ameliorative drug trials. Olfactory threshold, discrimination and identification can be reliably recorded in the early stages of neurodegenerative diseases. The current study has examined the ability of various olfactory functions in predicting cognitive decline in a community-dwelling sample. A group of 308 participants, aged 46-86 years old, were recruited for this study. After 3 years of follow-up, participants were divided into cognitively declined and non-declined groups based on their performance on a neuropsychological battery. Assessment of olfactory functions using the Sniffin' Sticks battery indicated that, contrary to previous findings, olfactory discrimination, but not olfactory identification, significantly predicted subsequent cognitive decline (odds ratio = 0.869; P<0.05; 95% confidence interval = 0.764-0.988). The current study findings confirm previously reported associations between olfactory and cognitive functions, and indicate that impairment in olfactory discrimination can predict future cognitive decline. These findings further our current understanding of the association between cognition and olfaction, and support olfactory assessment in screening those at higher risk of dementia.

Leptospirosis in cattle: a challenging scenario for the understanding of the epidemiology

All over the world, leptospirosis has been reported as one of the major causes of reproductive failure in cattle and other ruminants, determining abortions, stillbirth, weak newborns and decrease in their growth rate and milk production. Nevertheless, despite its importance, it is still a challenging disease, from what scarce information about epidemiology, prophylaxis and control is available nowadays. During the last decades of the last century, many epidemiological studies have been conducted in several countries, mainly based on serology. According to those studies, a seroepidemiological scenario has been stated for different regions, where different serovars were reported for cattle. Nevertheless, a huge problem is that, when efforts are made in order to increase the collection of local strains (isolates), it has been demonstrated that the scenario that emerges from those studies contrasts with those previously determined by serology. Despite the large number of serological studies worldwide, the number of isolates is scarce. Isolation technique is a very delicate procedure that needs no contamination, fast processing and long delay to produce a positive result, what may corroborate to the lack of information for the comparison between serology versus bacteriological data, mainly in developing countries. It is noteworthy that the epidemiological scenario now acknowledged may not represent what really occurs in many parts of the world, particularly on those tropical regions where the disease is endemic. Consequently, the current knowledge about epidemiology and control, as well as the available diagnostic tools and the commercial vaccines, may not be adequate for those regions, what leads to a frustrating scenario of endemicity and difficulties on the control of the disease. Without a huge effort in the culturing of local strains, besides the advances on molecular typing, leptospirosis will not be defeated and will probably remain endemic in the developing countries, leading to important economic hazards in animal production and risks to public health in those regions.

The -491AA polymorphism in the APOE gene is associated with increased plasma apoE levels in Alzheimer's disease

Recent evidence suggests that a polymorphism in the regulatory region of the apolipoprotein E gene (APOE) is associated with an increased risk for developing Alzheimer's disease (AD) independent of that conveyed by the epsilon4 allele of APOE. Previous work by our group indicated that plasma apolipoprotein E (apoE) levels were elevated in AD, raising the possibility that the -491 genotype might modify AD risk by increasing expression of the APOE gene. In a total of 638 individuals the -491AA genotype was significantly associated with AD (P < 0.005) while the TT genotype was associated with controls (P < 0.005). In 138 individuals the AA genotype showed significantly higher plasma apoE levels, independent of epsilon4 and AD status (P < 0.01) as well as within control and AD groups (P < 0.05). Within the AD group the AA genotype showed increased apoE levels when compared to AA controls (P < 0.0001). These results suggest that the -491 AA genotype is associated with increased plasma apoE levels, providing a potential basis for elucidating how that genotype increases the risk for developing AD.

APOE-epsilon4 and APOE -491A polymorphisms in individuals with subjective memory loss

The accurate clinical diagnosis of Alzheimer's disease can only be made with a high degree of certainty in specialized centres. The identification of predictive or diagnostic genetic factors may improve accuracy of disease prediction or diagnosis. One major genetic risk factor, the epsilon4 allele of the apolipoprotein E gene, is universally recognised. We have recently shown that the A allele of the apolipoprotein E, -491A/T promoter polymorphism is also an important risk factor for Alzheimer's disease in an Australian population. We designed the present study to investigate the association between apolipoprotein E genotype, -491A/T polymorphism, plasma apoE levels and the subjective experience of memory decline among 98 subjects and 49 age, gender and education-matched normal controls. An increased frequency of the epsilon4 allele of apolipoprotein E was significantly associated with the 'memory complainers' group (OR = 2.35, P = 0.02) as was the A allele of the -491A/T polymorphism (OR = 2, P = 0.02). Among all subjects, only seven individuals were homozygous for both of these alleles, and six of these seven individuals belonged to the 'memory complainers' group. This sub-group also had relatively elevated plasma apolipoprotein E levels (P < 0.01) and tended to score lower on the Mini-Mental State Examination (MMSE) and Cambridge Cognition Test. These data suggest that the epsilon4 allele of apolipoprotein E and the -491A allele are over-represented among individuals who complain of memory difficulties. Follow-up studies should clarify whether these genotypes and phenotypes are useful in the prediction and/or diagnosis of Alzheimer's disease.

Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

The electronic states of pyrimidine studied by VUV photoabsorption and electron energy-loss spectroscopy

The electronic state spectroscopy of pyrimidine C(4)H(4)N(2) has been investigated using both high resolution VUV photoabsorption in the energy range 3.7 to 10.8 eV (335 to 115 nm) and lower resolution electron energy loss in the range 2 to 15 eV. The low energy absorption band, assigned to the (pi*) <-- 7b(2)(n(N)) (1(1)B(1)<-- 1(1)A(1)) transition, at 3.85(4) eV and the vibrational progressions superimposed upon it have been observed for the first time, due to the availability of a high-resolution photon beam (0.075 nm), corresponding to 3 meV at the midpoint of the energy range studied. Vibronic coupling has been shown to play an important role dictating the nature of the observed excited states, especially for the lowest (1)B(1) state. The 2(1)B(1) state is proposed to have its origin at 7.026 eV according to the vibrational excitation reported in this energy region (7.8-8.4 eV). New experimental evidence of 4(1)A(1) state with a maximum cross section at 8.800 eV is supported by previous ab initio quantum chemical calculations. Rydberg series have been assigned converging to the three lowest ionisation energy limits, 9.32 eV ((2)B(2)), 10.41 eV ((2)B(1)) and 11.1 eV ((2)A(1) + (2)A(2)) with new members reported for the first time and classified according to the magnitude of the quantum defects (delta). Additionally, the absolute differential cross section for inelastic electron scattering has been measured for the most intense band from 6.9 to 7.8 eV assigned to (1)pipi* (3(1)A(1) + 2(1)B(2)).

Negative ion formation in potassium-nitromethane collisions

Ion-pair formation in gaseous nitromethane (CH(3)NO(2)) induced by electron transfer has been studied by investigating the products of collisions between fast potassium atoms and nitromethane molecules using a crossed molecular-beam technique. The negative ions formed in such collisions were analysed using time-of-flight mass spectroscopy. The six most dominant product anions are NO(2)(-), O(-), CH(3)NO(2)(-), OH(-), CH(2)NO(2)(-) and CNO(-). By using nitromethane-d(3) (CD(3)NO(2)), we found that previous mass 17 amu assignment to O(-) delayed fragment, is in the present experiment may be unambiguously assigned to OH(-). The formation of CH(2)NO(2)(-) may be explained in terms of dissociative electron attachment to highly vibrationally excited molecules.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

Electron transfer-induced fragmentation of thymine and uracil in atom-molecule collisions

Ion-pair formation has been studied in hyperthermal (30-100 eV) neutral potassium collisions with gas phase thymine (C(5)H(6)N(2)O(2)) and uracil (C(4)H(4)N(2)O(2)). Negative ions formed by electron transfer from the alkali atom to the target molecule were analysed by time-of-flight (TOF) mass spectrometry. The most abundant product anions are assigned to CNO(-) and (U-H)(-)/(T-H)(-) and the associated electron transfer mechanisms are discussed. Special emphasis is given to the enhancement of ring breaking pathways in the present experiments, notably CNO(-) formation, compared with free electron attachment measurements.

The Brazilian Peritoneal Dialysis Multicenter Study (BRAZPD) : characterization of the cohort

The Brazilian Peritoneal Dialysis Multicenter Study (BRAZPD) was launched in December 2004 aiming to collect data monthly and continuously from a representative cohort, allowing for a continuous snapshot of the peritoneal dialysis (PD) reality in the country. This is an observational study of PD patients comprising follow-up from December 2004 to February 2007 (mean follow-up of 13.6 months-ranging from 1 to 26 months) in 114 Brazilian centers. All centers report data through a central web-based database. After an initial baseline retrospective data collection, all patients are followed prospectively every month until they drop out from the PD program. Total number of patients recruited until February 2007 was 3226 (2094 incident patients). Mean age was 54+/-19 years (37% above 65 years old), with 55% females and 64% Caucasians. The more frequent causes of renal failure were diabetic nephropathy (34%), renal vascular disease associated with hypertension (26%), and glomerulopathies (13%). The most common comorbidities were hypertension (76%), diabetes (36%), and ischemic heart disease (23%). Automated PD (APD) was the modality utilized in 53%. The estimated overall peritonitis rate was 1 episode per 30 patient-months (most frequently due to Staphylococcus aureus). The total dropout rate was 33%, mainly due to deaths, whereas 20% of dropouts were due to renal transplant. The gross mortality was 17.6% and the main causes of mortality were cardiovascular diseases (40%) and infections (15%). The initial results of this first Brazilian PD registry provide a unique opportunity to develop future clinical studies addressing specific PD questions in the Brazilian reality and context.

Isolation of Leptospira interrogans Hardjoprajitno from vaginal fluid of a clinically healthy ewe suggests potential for venereal transmission

A total of 15 adult ewes from one flock known to be seroreactive for leptospirosis was studied. Urine and vaginal fluid were collected from each animal to test for the presence of leptospires using bacterial culture and conventional PCR methods. One pure culture of Leptospira sp. was obtained from the vaginal fluid sample of a non-pregnant ewe. The isolate was characterized by DNA sequencing of the rrs and secY genes, variable-number of tandem-repeats (VNTR) analysis and serogrouping, and the isolate was typed as Leptospira interrogans serogroup Sejroe serovar Hardjo type Hardjoprajitno. This report indicates the presence of viable Leptospira in the vaginal fluid of a ewe, suggesting the potential for venereal transmission of leptospires in sheep.

Electron attachment and electron ionization of acetic acid clusters embedded in helium nanodroplets

The effect of incident electrons on acetic acid clusters is explored for the first time. The acetic acid clusters are formed inside liquid helium nanodroplets and both cationic and anionic products ejected into the gas phase are detected by mass spectrometry. The cation chemistry (induced by electron ionization at 100 eV) is dominated by production of protonated acetic acid (Ac) clusters, Ac(n)H(+), although some fragmentation is also observed. In the case of anion production (at 2.8 eV electron energy) there is a clear distinction between the monomer and the clusters. For the monomer the dominant product is the dehydrogenated species, [Ac-H](-), whereas for the clusters both the parent anion, Ac(n)(-), and the dehydrogenated species, [Ac(n)-H](-), have similar abundances. A particularly intriguing contrast between the monomer and cluster anions is that helium atoms are seen attached to the latter whereas no evidence of helium atom attachment is found for the monomer. This surprising observation is attributed to the formation of acyclic (head-to-tail) acetic acid clusters in helium nanodroplets, which have more favourable electronic properties for binding helium atoms. The acyclic clusters represent a local minimum on the potential energy surface and in the case of the dimer this is distinct from the cyclic isomer (the global minimum) identified in gas phase experiments.

Valence shell electronic spectroscopy of isoprene studied by theoretical calculations and by electron scattering, photoelectron, and absolute photoabsorption measurements

The first ab initio calculations (vertical energies and oscillator strengths) are reported for the neutral electronic transitions of isoprene (2-methyl-1,3-butadiene), CH(2)CHC(CH(3))CH(2). The VUV photoabsorption spectroscopy of the molecule is presented in the energy range 4.6 to 10.8 eV (270-125 nm) with the highest resolution yet reported above 6.05 eV, revealing new spectral features. Valence and Rydberg transitions have been assigned in accordance with the theoretical results and the associated vibronic series have been analysed. The absolute photoabsorption cross sections at energies below 6.89 eV have been used to calculate the photolysis lifetime of isoprene in the upper stratosphere (20-50 km). Electron energy loss spectroscopy (EELS) measurements have enabled further photoabsorption cross sections to be derived in the range 9-28 eV. The first ab initio calculations have been carried out to determine excitation energies to the lowest energy ionic states of isoprene. The calculations are compared with the He(i) photoelectron spectrum (8 to 17 eV) and new vibrational structure is observed in the first photoelectron band.

Impact of an external electron acceptor on phosphorus mobility between water and sediments

The present work assessed the impact of an external electron acceptor on phosphorus fluxes between water and sediment interface. Microcosm experiments simulating a sediment microbial fuel cell (SMFC) were carried out and phosphorus was extracted by an optimized combination of three methods. Despite the low voltage recorded, ~96 mV (SMFC with carbon paper anode) and ~146 mV (SMFC with stainless steel scourer anode), corresponding to a power density of 1.15 and 0.13 mW/m(2), it was enough to produce an increase in the amounts of metal bound phosphorus (14% vs 11%), Ca-bound phosphorus (26% vs 23%), and refractory phosphorus (33% vs 28%). These results indicate an important role of electroactive bacteria in the phosphorus cycling and open a new perspective for preventing metal bound phosphorus dissolution from sediments.

Association between presenilin-1 Glu318Gly mutation and familial Alzheimer's disease in the Australian population

Mutations in the presenilin-1 (PS-1) gene on chromosome 14 account for the majority of early-onset familial Alzheimer's disease (FAD) cases. To date, more than 90 mutations have been identified and, while most of these mutations are completely penetrant, the Glu318Gly mutation has been suggested to be partially penetrant. These findings indicate that it may play a similar role to apolipoprotein E (APOE)-epsilon4 by acting as a genetic risk factor for AD. In the current study, a total of 682 subjects were tested to assess the frequency of the Glu318Gly mutation in AD in the Australian population. The Glu318Gly mutation was identified in six sporadic late-onset AD patients, four FAD patients (unrelated) and in nine control subjects. The frequency of this mutation was highest in the familial AD group (8.7%) and lowest in control subjects (2.2%). When the mutation frequencies were compared, we found a statistically significant difference between the latter two groups (Fisher's exact test, P < 0.05). The genotype frequency of the Glu318Gly mutation in all AD cases and controls in the Australian population was 2.8%. This frequency is comparable to that observed for the Dutch population (3.2%), but not for the Finnish population (6.8% and 6.0%) or the Spanish population (5.3%). These findings show that the frequency of the Glu318Gly mutation is increased in FAD patients, suggesting a potential role as a genetic risk factor contributing to the pathogenesis of familial AD.

Diagnosis and control of an outbreak of leptospirosis in goats with reproductive failure

This study presents a Brazilian goat herd with reproductive failure over 2009-2010, in which there were abortions (22/50; 44%), embryonic resorption (6/50; 12%) and neonatal deaths (2/50; 4%). A diagnosis of leptospirosis was made, based on serology (microscopic agglutination test - MAT), bacterial culture, and polymerase chain reaction (PCR). Antibiotic therapy, specific vaccination protocols and changes in management practices were instigated. One year after the outbreak, diagnostic methods were repeated and reproductive performance re-analysed. Soon after the outbreak, 61/125 (48.8%) of the goats were seropositive for Leptospira. Pure isolates of Leptospira were not obtained, but Leptospira PCR testing was positive in 48/50 (96%) urine samples. After 1 year only 4.2% were seropositive and the occurrence of reproductive problems decreased roughly 10-fold, although five goats (10.4%) remained PCR-positive. A broad-based management approach, including serological and molecular diagnostic methods, vaccination, antibiotic treatment, and alteration of some environmental aspects, were critical to the control of this outbreak, thereby minimising subsequent reproductive failures and economic losses.

Phosphorus fractionation in volcanic lake sediments (Azores - Portugal)

The phosphorus distribution in volcanic sediments of three lakes that are under different anthropogenic pressures in São Miguel island (Azores - Portugal) was evaluated using a sequential extraction scheme. The P-fractionation scheme employs sequential extractions of sediment with NH4Cl, bicarbonate-dithionite (BD), NaOH (at room temperature), HCl and NaOH (at 85 degrees C) to obtain five P-fractions. The P-fractionation shows that in lakes with higher trophic status (Lake Furnas and Lake Sete Cidades), the NaOH extracted P is the dominant fraction, that contribute with more than 50% to total sedimentary phosphorus. The rank order of P-fractionation for these two lakes was NaOH>NaOH (85 degrees C)>HCl>BD>NH4Cl for Furnas lake and NaOH>HCl>NaOH (85 degrees C)>NH4Cl>BD for Sete Cidades lake. On the other hand, the trend of P contribution in the oligotrophic lake Fogo shows that the most inert P pools have the higher concentrations, with more than 50% of the P contribution from the last extraction step with NaOH at 85 degrees C. For this lake, the rank order of P-fractionation was NH4Cl>BD>NaOH>HCl>NaOH (85 degrees C). The Phosphorus Maximum Solubilization Potential (P-MSP) was also calculated and the results show that for the more bio-available P-fractions (first and second extraction step), the P-MSP values for Furnas and Sete Cidades lakes are sensibly higher than the results obtained in Fogo lake, an indication of the non-point diffuse load discharged in the first ones.

Mineral cycling and pH gradient related with biological activity under transient anoxic-oxic conditions: effect on P mobility in volcanic lake sediments

Phosphorus (P) mobility from the sediments to the water column is a complex phenomenon that is generally assumed to be mainly redox sensitive and promoted by anoxic conditions. Thus, artificial aeration of the hypolimnium has been used as a remediation technique in eutrophic water bodies but several times with unexpected disappointing results. To optimize lake restoration strategies, the aim of the present study is to assess the P flux from the sediments under transient anoxic-conditions and to identify the relevant drivers. P sequential extraction, microprofiling (of pH, O2 and H2S), and bacterial community identification were performed on a sediment microcosm approach. The results demonstrated that the overall P release from sediments to the water column during transient phase was higher during the oxic phase, mainly from pH sensitive matrixes. The microprofiles signature suggests that the observed pH gradient during the oxic phase can be a result of H2S oxidation in suboxic layers spatially separated and pared to O2 reduction in top layers, through an electroactive bacterial network. These findings point to an additional driver to be considered when assessing P mobility under transient anoxic-oxic conditions, which would derive from pH gradients, built on the microbial electrical activity in sediments from freshwaters volcanic lakes.