Effects of hydrogeochemistry on the microbial ecology of terrestrial hot springs

Temperature, pH, and hydrochemistry of terrestrial hot springs play a critical role in shaping thermal microbial communities. However, the interactions of biotic and abiotic factors at this terrestrial-aquatic interface are still not well understood on a global scale, and the question of how underground events influence microbial communities remains open. To answer this, 11 new samples obtained from the El Tatio geothermal field were analyzed by 16S rRNA amplicon sequencing (V4 region), along with 191 samples from previous publications obtained from the Taupo Volcanic Zone, the Yellowstone Plateau Volcanic Field, and the Eastern Tibetan Plateau, with their temperature, pH, and major ion concentration. Microbial alpha diversity was lower in acid-sulfate waters, and no significant correlations were found with temperature. However, moderate correlations were observed between chemical parameters such as pH (mostly constrained to temperatures below 70°C), SO4 2- and abundances of members of the phyla Armatimonadota, Deinococcota, Chloroflexota, Campilobacterota, and Thermoplasmatota. pH and SO4 2- gradients were explained by phase separation of sulfur-rich hydrothermal fluids and oxidation of reduced sulfur in the steam phase, which were identified as key processes shaping these communities. Ordination and permutational analysis of variance showed that temperature, pH, and major element hydrochemistry explain only 24% of the microbial community structure. Therefore, most of the variance remained unexplained, suggesting that other environmental or biotic factors are also involved and highlighting the environmental complexity of the ecosystem and its great potential to test niche theory ecological associated questions. IMPORTANCE This is the first approach to investigate whether geothermal processes could have an influence on the ecology of thermal microbial communities on a global scale. In addition to temperature and pH, microbial communities are structured by sulfate concentrations, which depends on the tectono-magmatic settings (such as the depth of magmatic chambers) and the local settings (such as the availability of a confining layer separating NaCl waters from steam after phase separation) and the possibility of mixing with more diluted fluids. Comparison of microbial communities from different geothermal areas by homogeneous sequence processing showed that no significant geographic distance decay was detected on the microbial communities according to Bray-Curtis, Jaccard, unweighted, and weighted Unifrac similarity/dissimilarity indices. Instead, an ancient potential divergence in the same taxonomic groups is suggested between globally distant thermal zones.

Global phylogenomic novelty of the Cas1 gene from hot spring microbial communities

The Cas1 protein is essential for the functioning of CRISPR-Cas adaptive systems. However, despite the high prevalence of CRISPR-Cas systems in thermophilic microorganisms, few studies have investigated the occurrence and diversity of Cas1 across hot spring microbial communities. Phylogenomic analysis of 2,150 Cas1 sequences recovered from 48 metagenomes representing hot springs (42–80°C, pH 6–9) from three continents, revealed similar ecological diversity of Cas1 and 16S rRNA associated with geographic location. Furthermore, phylogenetic analysis of the Cas1 sequences exposed a broad taxonomic distribution in thermophilic bacteria, with new clades of Cas1 homologs branching at the root of the tree or at the root of known clades harboring reference Cas1 types. Additionally, a new family of casposases was identified from hot springs, which further completes the evolutionary landscape of the Cas1 superfamily. This ecological study contributes new Cas1 sequences from known and novel locations worldwide, mainly focusing on under-sampled hot spring microbial mat taxa. Results herein show that circumneutral hot springs are environments harboring high diversity and novelty related to adaptive immunity systems.

Taxonomic Novelty and Distinctive Genomic Features of Hot Spring Cyanobacteria

Several cyanobacterial species are dominant primary producers in hot spring microbial mats. To date, hot spring cyanobacterial taxonomy, as well as the evolution of their genomic adaptations to high temperatures, are poorly understood, with genomic information currently available for only a few dominant genera, including Fischerella and Synechococcus. To address this knowledge gap, the present study expands the genomic landscape of hot spring cyanobacteria and traces the phylum-wide genomic consequences of evolution in high temperature environments. From 21 globally distributed hot spring metagenomes, with temperatures between 32 and 75°C, 57 medium- and high-quality cyanobacterial metagenome-assembled genomes were recovered, representing taxonomic novelty for 1 order, 3 families, 15 genera and 36 species. Comparative genomics of 93 hot spring genomes (including the 57 metagenome-assembled genomes) and 66 non-thermal genomes, showed that the former have smaller genomes and a higher GC content, as well as shorter proteins that are more hydrophilic and basic, when compared to the non-thermal genomes. Additionally, the core accessory orthogroups from the hot spring genomes of some genera had a greater abundance of functional categories, such as inorganic ion metabolism, translation and post-translational modifications. Moreover, hot spring genomes showed increased abundances of inorganic ion transport and amino acid metabolism, as well as less replication and transcription functions in the protein coding sequences. Furthermore, they showed a higher dependence on the CRISPR-Cas defense system against exogenous nucleic acids, and a reduction in secondary metabolism biosynthetic gene clusters. This suggests differences in the cyanobacterial response to environment-specific microbial communities. This phylum-wide study provides new insights into cyanobacterial genomic adaptations to a specific niche where they are dominant, which could be essential to trace bacterial evolution pathways in a warmer world, such as the current global warming scenario.

Active Crossfire Between Cyanobacteria and Cyanophages in Phototrophic Mat Communities Within Hot Springs

Cyanophages are viruses with a wide distribution in aquatic ecosystems, that specifically infect Cyanobacteria. These viruses can be readily isolated from marine and fresh waters environments; however, their presence in cosmopolitan thermophilic phototrophic mats remains largely unknown. This study investigates the morphological diversity (TEM), taxonomic composition (metagenomics), and active infectivity (metatranscriptomics) of viral communities over a thermal gradient in hot spring phototrophic mats from Northern Patagonia (Chile). The mats were dominated (up to 53%) by cosmopolitan thermophilic filamentous true-branching cyanobacteria from the genus Mastigocladus, the associated viral community was predominantly composed of Caudovirales (70%), with most of the active infections driven by cyanophages (up to 90% of Caudovirales transcripts). Metagenomic assembly lead to the first full genome description of a T7-like Thermophilic Cyanophage recovered from a hot spring (Porcelana Hot Spring, Chile), with a temperature of 58°C (TC-CHP58). This could potentially represent a world-wide thermophilic lineage of podoviruses that infect cyanobacteria. In the hot spring, TC-CHP58 was active over a temperature gradient from 48 to 66°C, showing a high population variability represented by 1979 single nucleotide variants (SNVs). TC-CHP58 was associated to the Mastigocladus spp. by CRISPR spacers. Marked differences in metagenomic CRISPR loci number and spacers diversity, as well as SNVs, in the TC-CHP58 proto-spacers at different temperatures, reinforce the theory of co-evolution between natural virus populations and cyanobacterial hosts. Considering the importance of cyanobacteria in hot spring biogeochemical cycles, the description of this new cyanopodovirus lineage may have global implications for the functioning of these extreme ecosystems.

A Polyphasic and Taxogenomic Evaluation Uncovers Arcobacter cryaerophilus as a Species Complex That Embraces Four Genomovars

The species Arcobacter cryaerophilus is found in many food products of animal origin and is the dominating species in wastewater. In addition, it is associated with cases of farm animal and human infectious diseases,. The species embraces two subgroups i.e., 1A (LMG 24291^T = LMG 9904^T) and 1B (LMG 10829) that can be differentiated by their 16S rRNA-RFLP pattern. However, some authors, on the basis of the shared intermediate levels of DNA-DNA hybridization, have suggested abandoning the subgroup classification. This contradiction indicates that the taxonomy of this species is not yet resolved. The objective of the present study was to perform a taxonomic evaluation of the diversity of A. cryaerophilus. Genomic information was used along with a Multilocus Phylogenetic Analysis (MLPA) and phenotypic characterization on a group of 52 temporally and geographically dispersed strains, coming from different types of samples and hosts from nine countries. The MLPA analysis showed that those strains formed four clusters (I–IV). Values of Average Nucleotide Identity (ANI) and in silico DNA-DNA Hybridization (isDDH) obtained between 13 genomes representing strains of the four clusters were below the proposed cut-offs of 96 and 70%, respectively, confirming that each of the clusters represented a different genomic species. However, none of the evaluated phenotypic tests enabled their unequivocal differentiation into species. Therefore, the genomic delimited clusters should be considered genomovars of the species A. cryaerophilus. These genomovars could have different clinical importance, since only the cluster I included strains isolated from human specimens. The discovery of at least one stable distinctive phenotypic character would be needed to define each cluster or genomovar as a different species. Until then, we propose naming them “A. cryaerophilus gv. pseudocryaerophilus” (Cluster I = LMG 10229^T), “A. cryaerophilus gv. crypticus” (Cluster II = LMG 9065^T), “A. cryaerophilus gv. cryaerophilus” (Cluster III = LMG 24291^T) and “A. cryaerophilus gv. occultus” (Cluster IV = LMG 29976^T).

Potential probiotic yeasts isolated from the fish gut protect zebrafish (Danio rerio) from a Vibrio anguillarum challenge

Due to the negative consequences associated with the use of antibiotics, researchers, and food producers have studied alternatives, such as probiotics, for the control of fish diseases. The probiotic properties of yeasts in aquaculture have been scarcely considered. The present study investigated the probiotic properties of local yeast strains for aquaculture application in the protection of bacterial diseases. Yeast strains (n = 15), previously isolated from the intestinal gut of healthy salmonids, yellowtail, and croaker, were evaluated for their protection of zebrafish larvae following a Vibrio anguillarum challenge. We developed an infection model on zebrafish larvae with V. anguillarum, observing rapid mortality (≥50%) 5 days post-immersion challenge. Infection of Tg(Lyz:DsRed)^nz50 larvae with fluorescent-marked V. anguillarum showed the oro-intestinal as the natural route of infection concomitant with an inflammatory response of the larvae reflected by neutrophil migration outside the hematopoietic tissue. Thirteen of 15 strains increased the percentage of larvae survival after the V. anguillarum challenge, although no yeast showed in vitro anti-V. anguillarum activity. In a subset of yeasts, we explored yeast–larvae interactions using fluorescent yeast and evaluated larvae colonization by culture analysis. All fluorescent yeasts were located in the gastrointestinal tract until 5 days post-inoculation (dpi). Yeasts reached 10³ CFU/larvae at 0 dpi, although the persistence until 5 dpi of the viable yeast in the gut was different among the strains. These results reveal that some yeasts isolated from the gut of fish could be potential probiotics, reducing the mortality associated to V. anguillarum challenge, and suggest that gut colonization could be involved in the protective effect. Future studies should elucidate other mechanisms involved in yeast protection and verify the beneficial effects of probiotic use in commercial fish species.

[Anterolateral approach for minimally invasive hip surgery]

INTRODUCTION

The approach for total hip arthroplasty (THA) using a mini-incision has been used progressively to decrease morbidity, achieve prompt patient recovery without an increased risk and shorten the hospital stay. However, the advantages and probable complications of these approaches are not clear. The objective of this paper is to compare the preliminary perioperative results of two groups of patients undergoing THA, one using the standard approach and the second one with a mini-incision.

MATERIAL AND METHODS

170 patients underwent surgery; they were divided into two groups. In group I (GI) patients an anterolateral mini-incision was performed, and in group II (GII) patients a standard Watson-Jones incision was used. Mean incision length was 8 cm in GI and 20 cm in GII.

RESULTS

No statistically significant differences were found between both groups in the clinical and radiographic results and in the complications; however, a significant difference was found in the need for transfusions, wound size and hospital stay.

CONCLUSIONS

This study showed that primary THA with a mini-incision was a safe procedure that reduced the operative time without increasing the complications.

Severely elevated intrarenal arterial impedance and abnormal venous flow pattern in a normal functioning kidney graft

Serial Doppler sonographic impedance measurements represent the most common diagnostic method for noninvasive monitoring of kidney grafts. Severely elevated arterial impedance is almost always associated with graft dysfunction. However, we describe in the present work a renal transplant recipient with optimal graft function despite permanently elevated arterial impedance (pulsatility index (PI) ranging from 2.9-3.0, and resistive index (RI) = 1.0 as well as an abnormal venous flow pattern. In contrast, the contralateral graft from the same cadaver donors transplanted into a 17-year-old female patient displayed normal range PI and RI values in conjunction with a normal serum creatinine. Known causes of arterial impedance elevation such as rejection, cyclosporine, urinary obstruction, and external graft compression were excluded. Other extrarenal causes of high impedance, such as aortic insufficiency and reduced aortic compliance, were also excluded. No evidence of impaired venous outflow at the site of the anastomosis of the main renal vein to the iliac vein was found. Those findings support the view that impedance indexes are hemodynamic rather than functional parameters.

Renal duplex ultrasonography in the diagnosis and follow-up of a case of accelerated transplant rejection treated with OKT3

Several studies have discussed the value of ultrasonography in the differential diagnosis of early renal allograft dysfunction. However, much controversy still remains regarding its real usefulness in this clinical setting. Among the causes of early graft dysfunction, accelerated rejection is one of the most serious and leads frequently to early graft loss; early diagnosis and aggressive therapy are essential to prevent irreversible graft damage or even graft rupture. Limited attention has been paid to the evaluation of accelerated rejection treated with monoclonal CD3 antibodies by means of combined B-mode and Doppler ultrasonography. We report one such a case with a favorable outcome.

[Safety in the switching traditional cyclosporin to microemulsion cyclosporin in stable renal transplant patients: cooperative study]

In an open clinical trial we assessed the tolerance and safety of the 1:1 conversion of traditional cyclosporine A (CyA) to a new cyclosporine formulation based on a microemulsion technology (CyN) in 18 patients with stable renal allografts. 56% patients were female. Median patient age was 40.9 +/- 3.2 years (range 18 to 65). Renal transplantation was performed in 24.1 +/- 4.6 months (range 6 to 67 months), prior to the beginning of the study, and 67% of the transplants were from cadaveric donor. The most frequent underlying renal disease was glomerulonephritis (44.4%). None of the patients entering the study were withdrawn prematurely. After 2 weeks of observation for graft function stability, the study was divided in two phases: I: during 4 weeks the patients received CyA traditional at fixed doses (Mean dose administered 3.056 +/- 0.25 mg/Kg/d) and II: during the consecutive 6 weeks with conversion to CyN, with doses adjustment as required (Mean dose 2.887 +/- 0.21 mg/Kg/d). Clinical events, adverse reactions and laboratory parameters were evaluated. Levels of 100-200 ng/ml measured by monoclonal specific fluorescence polarization immunoassay were considered appropriate. There were no significant changes in physical examination and laboratory parameters between phases. The incidence of adverse reactions reported in phase I was only gingival hypertrophy (5%) which persisted in phase II, qualified as probably related to the cyclosporine, and in phase II tremor in 17%, qualified as definitively related. Both drugs were well tolerated and there was no report of acute rejection during the study. We conclude that the tolerance and safety of the 1:1 conversion of CyA to CyN were confirmed by our results, and considering the improved pharmacokinetic properties of the second, the microemulsion presentation will be used preferentially as immunosuppressive drug in the treatment of stable kidney transplant patients.

[Impact of the Hospital Coordinator Program on obtaining kidneys for renal transplantation]

Limited organ supply is currently the major obstacle to the transplantation programs around the world. As an alternative to increase the organ donation rate, we undertook a preliminary transplant coordinator program study, during a 6 month period, in five public hospitals, as part of the National Transplant Program of the Centro Nacional de Diálisis y Trasplante. The primary objective of the Transplant Coordinator Program was donor detection and organ procurement, along with education of the community. Forty five predonors were detected, with an average age of 25.8 +/- 1.6 years, of these, 36 were men (80%). None of them was a voluntary donor. The most frequent diagnoses were cranial trauma in 57.8% and stroke in 22.2% Forty two percent (42.3%) of the predonors were detected in the emergency room, 33.3% in intensive care units and 24.4% in the surgery recovery room. The conversion rate of predonors to donors were 29%. The main causes for not conversion of predonors into donors were: family refusal 44%, sepsis 13%, cardiac arrest 13%, and reduced renal function 6%. In conclusion, the Transplant Coordinator Program allows to increase the predonor detection and gives good information for adequate management of donor and public educational campaign about the subject.

Multinational multicenter controlled trial comparing ceftibuten with cefaclor for the treatment of acute otitis media. Members of the Ceftibuten Otitis Media International Study Group

A randomized, controlled, single blind clinical trial was conducted in children with acute otitis media to evaluate the safety and efficacy of a 10-day course of therapy with ceftibuten 9 mg/kg taken as a single daily dose, up to a maximum daily dose of 400 mg, compared with cefaclor 40 mg/kg/day in three divided doses, up to a maximum of 1 g/day. Patients were evaluated any time from 1 to 3 days after completion of therapy (posttreatment follow-up). A total of 154 patients (106 ceftibuten, 48 cefaclor) were evaluable for efficacy. Clinical success as determined by resolution (cure) or improvement of signs and symptoms of infection were seen in 89 and 88% of patients treated with ceftibuten and cefaclor, respectively, at the posttreatment follow-up visit. At the extended follow-up visit (any time from 2 to 4 weeks after completion of therapy), clinical success was sustained in 88 and 82% of the ceftibuten-treated and cefaclor-treated patients, respectively. A total of 391 patients (264 ceftibuten, 127 cefaclor) were included in the safety analysis. Treatment-related adverse experiences occurred in 8% of ceftibuten-treated patients and 14% of cefaclor-treated patients. All were mild or moderate and the majority were gastrointestinal. There were no deaths or serious adverse events. The results of this study suggest that ceftibuten is an effective and well-tolerated alternative to other antibiotic therapies for the treatment of children with acute otitis media.

The influence of the blood levels of lead, aluminum and vanadium upon the arterial hypertension

The present study describes the relationship between the whole blood Pb, plasma Al and plasma V levels and the arterial hypertension, for four groups of individuals: 20 normotensive azotemic patients in periodic hemodialysis (CRF), 20 hypertensive azotemic patients in periodic hemodialysis (CRF-AHT), 20 individuals with severe essential hypertension and normal renal function (AHT) and 20 individuals with normal renal function and normal blood pressure (controls) evaluated during a period of 1 year. The renal population's blood Pb was comparable with that found in the non-renal groups. Blood Pb in the essential AHT was higher than in controls (P < 0.05). CRF and CRF-AHT showed higher Al levels than those individuals with normal renal function (P < 0.01). In CRF, plasma Al did not correlate with the arterial hypertension. Plasma Al was increased in the AHT individuals (P < 0.05) with respect to the control group, suggesting the possible influence of this metal in the appearance of the arterial hypertension. In this study, the CRF-AHT patients had plasma V statistically higher (P < 0.005) than controls. However, no differences were found between plasma V of CRF and CRF-AHT groups or between AHT and controls. These results suggest that V in AHT is of doubtful significance, except maybe when the renal failure and the arterial hypertension appear together. In summary, high levels of blood Pb and plasma Al are associated with arterial hypertension in individuals without renal disease. Higher plasma V levels were not found in hypertensives with normal renal function with respect to controls.

Bone metal content in patients with chronic renal failure

Bone accumulation of metals, other than aluminum (Al), in patients with chronic renal failure (CRF) has rarely been studied. We report the bone and blood levels of iron (Fe), vanadium (V), lead (Pb), Al and calcium (Ca) in 18 CRF patients on long-term hemodialysis and in 14 controls (C). Significant increments in mean blood Al (1,300%), V (160%) and Fe (60%) and decrease in blood Pb (-50%) were found in the patients with CRF. Renal subjects had higher bone concentrations (mean +/- S.E.M.; microgram/g of bone) of Al (CRF = 129.1 +/- 16.9; C = 12.6 +/- 2.9; P < 0.0001), Fe (CRF = 940.4 +/- 133.4; C = 263.4 +/- 49.0; P < 0.0001) and V (CRF = 2.55 +/- 0.43; C = 1.39 +/- 0.36; P = 0.0308) and lower Ca (CRF = 268.2 +/- 11.1 mg/g; C = 377.2 +/- 28.1; P = 0.0017). A positive correlation was found between bone Al and V (r = 0.355, P < 0.05). Results indicated that a significant bone accumulation of Al, Fe and V, but not Pb, occurred in the hemodialyzed azotemic individuals.

Removal of trace metals by continuous ambulatory peritoneal dialysis after desferrioxamine B chelation therapy

We studied the removal of aluminum (Al), iron (Fe), copper (Cu), lead (Pb) and zinc (Zn) with continuous ambulatory peritoneal dialysis, before and after desferrioxamine B (DFO) administration (2 g intravenously) in two patients with chronic renal failure and Al-related osteopathy. Both patients had 4 peritoneal dialysis exchanges (2 liters each) per day. Blood concentrations of Al increased 413% (patient A) and 190% (patient B) after DFO. Patient B had a 15% increase in Fe; other metals remained unchanged. Dialysate efflux Al concentrations had peak post-DFO increments of 761% and 840% in patients 1 and 2, respectively. Peak post-DFO increments in Fe dialysate concentration were 342% and 89.5% in the respective patients. Dialysate/plasma (D/P) concentration ratios of Al increased from pre-DFO levels (mean +/- SEM) of 0.370 +/- 0.048 to 0.523 +/- 0.061 after DFO; similarly, Fe D/P ratios increased from 0.259 +/- 0.053 to 0.446 +/- 0.075 with DFO therapy. These results indicate an increase in the ultrafiltrable proportion of Al and Fe in plasma after DFO administration. During 3 days after DFO, patient 1 had a total removal of Al and Fe of 2.9 mg and 4.9 mg, respectively. Metal removal in patient 2 was 7.6 mg of Al and 2.7 mg of Fe. Peritoneal extraction of other trace metals was minor.