Effects of Albumin Treatment on Systemic and Portal Hemodynamics and Systemic Inflammation in Patients With Decompensated Cirrhosis.

BACKGROUND & AIMS: We investigated the effect of albumin treatment (20% solution) on hypoalbuminemia, cardiocirculatory dysfunction, portal hypertension, and systemic inflammation in patients with decompensated cirrhosis with and without bacterial infections. METHODS: We performed a prospective study to assess the effects of long-term (12 weeks) treatment with low doses (1 g/kg body weight every 2 weeks) and high doses (1.5 g/kg every week) of albumin on serum albumin, plasma renin, cardiocirculatory function, portal pressure, and plasma levels of cytokines, collecting data from 18 patients without bacterial infections (the Pilot-PRECIOSA study). We also assessed the effect of short-term (1 week) treatment with antibiotics alone vs the combination of albumin plus antibiotics (1.5 g/kg on day 1 and 1 g/kg on day 3) on plasma levels of cytokines in biobanked samples from 78 patients with bacterial infections included in a randomized controlled trial (INFECIR-2 study). RESULTS: Circulatory dysfunction and systemic inflammation were extremely unstable in many patients included in the Pilot-PRECIOSA study; these patients had intense and reversible peaks in plasma levels of renin and interleukin 6. Long-term high-dose albumin, but not low-dose albumin, was associated with normalization of serum level of albumin, improved stability of the circulation and left ventricular function, and reduced plasma levels of cytokines (interleukin 6, granulocyte colony-stimulating factor, interleukin 1 receptor antagonist, and vascular endothelial growth factor) without significant changes in portal pressure. The immune-modulatory effects of albumin observed in the Pilot-PRECIOSA study were confirmed in the INFECIR-2 study. In this study, patients given albumin had significant reductions in plasma levels of cytokines. CONCLUSIONS: In an analysis of data from 2 trials (Pilot-PRECIOSA study and INFECIR-2 study), we found that albumin treatment reduced systemic inflammation and cardiocirculatory dysfunction in patients with decompensated cirrhosis. These effects might be responsible for the beneficial effects of albumin therapy on outcomes of patients with decompensated cirrhosis. ClinicalTrials.gov, Numbers: NCT00968695 and NCT03451292.

A retrospective cohort study to assess PET-CT findings and clinical outcomes in Takayasu arteritis: does 18F-fluorodeoxyglucose uptake in arteries predict relapses?

The objective of this study is to investigate the use of PET-CT scan with 18F-fluorodeoxyglucose (18F-FDG) as a method to predict outcomes in patients with Takayasu arteritis (TAK), as well as to analyze associations between 18F-FDG PET-CT findings with disease relapses, sustained remission, new angiographic lesions, ischemic events, and changes in therapy for TAK. At baseline assessment, 36 TAK patients underwent 18F-FDG PET-CT scan and maximal standardized uptake value (SUVmax) in arteries ≥ 1.3 was predictive for clinical disease activity. Thirty-two TAK patients were then followed-up for a median 83.5 months. Twenty-three (71.9%) patients developed clinical relapses and new arterial lesions were observed in 14 (43.8%) cases. Disease relapses [85.0% vs. 50.0%, p = 0.049; odds ratio (OR): 5.667; 95% confidence interval (95 CI): 1.067-30.085] and the need for changing immunosuppressive therapy (85.0% vs. 41.7%, p = 0.018; OR: 7.933; 95CI: 1.478-42.581) were more frequently found in patients with SUVmax ≥ 1.3 at baseline compared with those presenting SUVmax < 1.3. No associations were found between SUVmax ≥ or < 1.3 in large arteries at baseline and the development of ischemic events, sustained remission or new angiographic lesions. In multivariate analysis, associations between baseline SUVmax ≥ 1.3 and disease relapses were not independent (hazard ratio: 1.07; 95 CI 0.39-2.92; p = 0.892). In conclusion, arterial SUVmax is marginally associated with disease relapses and with the need to change therapy in TAK. 18F-FDG uptake in large arteries is not associated with the development of new arterial lesions in TAK.

Regulation of the phosphate metabolism in Streptomyces genus: impact on the secondary metabolites.

The analysis of the inorganic phosphate effect over the antibiotics production is a long-distance history in the Streptomyces genus, which began almost at the same time that Michael Ende published his book entitled The Neverending Story. In some way, the unveiling of the pho regulon and its influence over the secondary metabolites production is an unfinished story, which keeps this subject as a trending topic, nowadays. Up to date, different studies have been releasing knowledge about particular areas of the pho regulon of different Streptomyces species. Nevertheless, for the first time, these knowledge drops are grouped in a review presenting a broad overview of the phosphate regulation and its impact over the secondary metabolites production in industrially relevant species. Even though the genetic response against phosphate scarcity is similar, as a whole, in different Streptomyces species, the fine-tuning is species-specific. Thus, the response regulator PhoP directly controls the secondary metabolites production in some species, whereas it regulates them in an indirect manner in other species. This information, unraveled in this review, is the result of the intensive analysis along last decade in several species of the genus that is allowing to distinguish how the phosphate response is unleashed in Streptomyces coelicolor, Streptomyces lividans, Streptomyces natalensis, Streptomyces lydicus, Streptomyces avermitilis, and Streptomyces tsukubaensis.

Analysis and validation of the pho regulon in the tacrolimus-producer strain Streptomyces tsukubaensis: differences with the model organism Streptomyces coelicolor.

Inorganic and organic phosphate controls both primary and secondary metabolism in Streptomyces genus. Metabolism regulation by phosphate in Streptomyces species is mediated by the PhoR-PhoP two-component system. Response regulator PhoP binds to conserved sequences of 11 nucleotides called direct repeat units (DRus), whose organization and conservation determine the binding of PhoP to distinct promoters. Streptomyces tsukubaensis is the industrial producer of the clinical immunosuppressant tacrolimus (FK506). A bioinformatic genome analysis detected several genes with conserved PHO boxes involved in phosphate scavenging and transport, nitrogen regulation, and secondary metabolite production. In this article, the PhoP regulation has been confirmed by electrophoretic mobility shift assays (EMSA) of the most relevant members of the traditional pho regulon such as the two-component system PhoR-P or genes involved in high-affinity phosphate transport (pstSCAB) and low-affinity phosphate transport (pit). However, the PhoP control over phosphatase genes in S. tsukubaensis is significantly different from the pattern reported in the model bacteria Streptomyces coelicolor. Thus, neither the alkaline phosphatase PhoA nor PhoD is regulated by PhoP. On the contrary, the binding of PhoP to the promoter of a novel putative phosphatase PhoX was confirmed. A crosstalk of the PhoP and GlnR regulators, which balances phosphate and nitrogen utilization, also occurs in S. tsukubaensis but slightly modified. Finally, PhoP regulates genes, like afsS, that link phosphate control and secondary metabolite production in S. tsukubaensis. In summary, there are notable differences between the regulation of specific genes of the pho regulon in S. tsukubaensis and the model organism S. coelicolor.

Clinical course and short-term mortality of cirrhotic patients with infections other than spontaneous bacterial peritonitis.

BACKGROUND & AIMS: Clinical course and risk factors of death in non-spontaneous bacterial peritonitis (SBP) infections are poorly known. We assessed the prevalence of acute kidney injury (AKI) and type-1 hepatorenal syndrome (HRS), hospital, 30-day and 90-day mortality and risk factors of death in 441 decompensated patients. METHODS: Analysis of 615 non-SBP infections (161 urinary infections (UTI), 95 cellulitis, 92 suspected infections, 92 bacteraemias, 84 pneumonias, 21 bronchitis, 18 cholangitis, 15 spontaneous empyema, 13 secondary peritonitis, 24 other). RESULTS: Ninety-six percent of infections solved. AKI and type-1 HRS were developed in 37% and 9% of infections respectively. Overall hospital, 30-day and 90-day mortality rates were 11%, 12% and 18% respectively. Clinical course and mortality differed markedly across infections. Endocarditis, osteoarticular infections, pneumonia, spontaneous bacteraemia, cholangitis, secondary peritonitis and UTI showed higher rates of AKI. Prevalence of type-1 HRS was not significantly different among infections. Endocarditis, secondary peritonitis, pneumonia and bacteraemia showed lower rates of renal impairment resolution and higher hospital mortality associated with AKI (42% vs 12%, P<.0001) or type-1 HRS (71% vs 27%, P=.003) than the rest of infections. Age (HR: 1.04), serum sodium (HR: 0.91), serum bilirubin (HR: 1.06), INR (HR: 1.91), hepatic encephalopathy (HR: 2.44), ascites (HR: 3.06) and multidrug-resistant isolation (HR: 2.27) at infection diagnosis were independent predictors of death during hospitalization. CONCLUSIONS: Non-SBP infections constitute a heterogeneous group regarding clinical course and prognosis. Endocarditis, secondary peritonitis, pneumonia and bacteraemia show worse prognosis. The combination of data of liver and renal dysfunction and of the type of infection allows the identification of patients with poor prognosis.

Relative adrenal insufficiency in decompensated cirrhosis: Relationship to short-term risk of severe sepsis, hepatorenal syndrome, and death.

UNLABELLED: The prevalence of relative adrenal insufficiency (RAI) in critically ill cirrhosis patients with severe sepsis is over 60% and associated features include poor liver function, renal failure, refractory shock, and high mortality. RAI may also develop in noncritically ill cirrhosis patients but its relationship to the clinical course has not yet been assessed. The current study was performed in 143 noncritically ill cirrhosis patients admitted for acute decompensation. Within 24 hours after hospitalization adrenal function, plasma renin activity, plasma noradrenaline and vasopressin concentration, and serum levels of nitric oxide, interleukin-6 and tumor necrosis factor alpha were determined. RAI was defined as a serum total cortisol increase <9 µg/dL after 250 µg of intravenous corticotropin from basal values <35 µg/dL. Patients were followed for 3 months. RAI was detected in 26% of patients (n = 37). At baseline, patients with RAI presented with lower mean arterial pressure (76 ± 12 versus 83 ± 14 mmHg, P = 0.009) and serum sodium (131 ± 7 versus 135 ± 5 mEq/L, P = 0.007) and higher blood urea nitrogen (32 ± 24 versus 24 ± 15 mg/dl, P = 0.06), plasma renin activity (7.1 ± 9.9 versus 3.4 ± 5.6 ng/mL*h, P = 0.03), and noradrenaline concentration (544 ± 334 versus 402 ± 316 pg/mL, P = 0.02). During follow-up, patients with RAI exhibited a higher probability of infection (41% versus 21%, P = 0.008), severe sepsis (27% versus 9%, P = 0.003), type-1 hepatorenal syndrome (HRS) (16% versus 3%, P = 0.002), and death (22% versus 7%, P = 0.01). CONCLUSION: RAI is frequent in noncritically ill patients with acute decompensation of cirrhosis. As compared with those with normal adrenal function, patients with RAI have greater impairment of circulatory and renal function, higher probability of severe sepsis and type-1 HRS, and higher short-term mortality.

Angiotensin II and ischemic preconditioning synergize to improve mitochondrial function while showing additive effects on ventricular postischemic recovery.

Recent studies indicate that the cardioprotective effects of ischemic preconditioning (IPC) against sustained ischemia/reperfusion can be replicated by angiotensin II (Ang II). However, it is not clear whether IPC and Ang II-induced preconditioning (APC) act through similar mechanisms or synergize to enhance cardioprotection. In this study, Langendorff-perfused rat hearts were subjected to IPC, APC, or their combination (IPC/APC) followed by ischemia/reperfusion. IPC, and less potently APC, significantly increased the percent recoveries of the left ventricular developed pressure, the first derivative of developed pressure, and the rate pressure product compared with control. Furthermore, the postischemic recovery of the heart was significantly higher for IPC/APC compared with IPC or APC. The improvements in cardiac function by IPC, APC, and IPC/APC were associated with similar reductions in lactate dehydrogenase release and infarct size. However, a significant improvement in mitochondrial respiration was observed with IPC/APC. The postischemic recovery observed with APC and IPC/APC was inhibited by treatment with losartan, an Ang II type-1 receptor blocker, during the preconditioning phase but not by chelerythrine, a pan-PKC inhibitor. Both drugs, however, abolished the enhanced mitochondrial respiration by IPC/APC. Altogether, these results indicate that APC and IPC interact through mechanisms that enhance cardioprotection by affecting cardiac function and mitochondrial respiration.

Trends in the biosynthesis and production of the immunosuppressant tacrolimus (FK506).

The current off-patent state of tacrolimus (FK506) has opened the hunting season for new generic pharmaceutical formulations of this immunosuppressant. This fact has boosted the scientific and industrial research on tacrolimus for the last 5 years in order to improve its production. The fast discovery of tacrolimus producer strains has generated a huge number of producers, which presents the biosynthetic cluster of FK506 as a high promiscuous genetic region. For the first time, the current state-of-the-art on the tacrolimus biosynthesis, production improvements and drug purification is reviewed. On one hand, all the genes involved in the tacrolimus biosynthesis, in addition to the traditional PKS/NRPS, as well as their regulation are analysed. On the other hand, tacrolimus direct and indirect precursors are reviewed as a straight manner to improve the final yield, which is a current trend in the field. Twenty years of industrial and scientific improvements on tacrolimus production are summarised, whereas future trends are also drafted.

Tracking of structural defects induced by Eu-doping in ß-Ag2MoO4: their influences on electrical properties.

In this study, several methods were employed to investigate the electrical characteristics of ß-Ag2MoO4 systems, both Eu-doped and undoped, synthesized using the microwave-assisted hydrothermal method. The focus extended to understanding how synthesis time influences material defects, with doping fixed at 1%. A systematic shift in the silver vacancy (VAg) concentration was observed within the doped ß-Ag2MoO4 system. Specifically, this study demonstrated that the incorporation of Eu3+ into polycrystalline ß-Ag2MoO4 initially increases the VAg concentration. However, as the synthesis time progresses, the VAg concentration decreases, resulting in alterations in the resulting electrical properties, arising from the intricate interplay between the number of grain boundaries and carrier density. By combining information obtained from photoluminescence, positron annihilation lifetime spectroscopy, and impedance spectroscopy, a comprehensive conduction mechanism was formulated, shedding light on both doped and undoped ß-Ag2MoO4 systems.

Effectiveness of video-assisted debriefing versus oral debriefing in simulation-based interdisciplinary health professions education: A randomized trial.

AIM: We aimed to compare the debriefing experience, simulation assessment, reflection, anxiety and simulation satisfaction of using oral debriefing versus video-assisted debriefing after a simulated clinical session in an interdisciplinary cohort of health sciences students. BACKGROUND: Debriefing is a reflective process that takes place after a clinical simulation and that can be performed either in a traditional way (oral) or using video-assisted debriefing. DESIGN: A randomized controlled trial was conducted in 143 health sciences students (35.7% male, 61.5% female). METHODS: The simulation scenario was designed to evaluate the procedure for donning and doffing personal protective equipment. Differences in debriefing experience, simulation assessment, reflection, anxiety and satisfaction were assessed. RESULTS: Regarding debriefing experience, significant differences were observed for the category "learning" (34.9 (6.13) vs. 36.7 (3.89); p = 0.039). For simulation assessment, significantly higher scores for all categories were identified in video-assisted debriefing compared with oral debriefing (p<0.001). There were also significant differences between the oral debriefing versus video-assisted debriefing for the overall score of reflection ability (86.97 (10.55) vs. 90.74 (9.67); p=0.028) as well as for the category "reflective communication" (24.72 (3.77) vs 26.04 (4.07); p=0.047). Perceived satisfaction was significantly higher in the video-assisted debriefing group compared with oral debriefing group (p <0.001). For anxiety, no significant differences were observed between debriefing groups. CONCLUSION: Video-assisted debriefing after a simulated clinical session improves debriefing experience, simulation assessment, reflection and simulation satisfaction, but does not increase anxiety compared with oral debriefing among health sciences students.

Prevalence and risk factors of infections by multiresistant bacteria in cirrhosis: a prospective study.

UNLABELLED: Epidemiology, risk factors, and clinical effect of infections by multiresistant bacteria in cirrhosis are poorly known. This work was a prospective evaluation in two series of cirrhotic patients admitted with infection or developing infection during hospitalization. The first series was studied between 2005 and 2007 (507 bacterial infections in 223 patients) and the second between 2010 and 2011 (162 bacterial infections in 110 patients). In the first series, 32% of infections were community acquired (CA), 32% healthcare associated (HCA), and 36% nosocomial. Multiresistant bacteria (92 infections; 18%) were isolated in 4%, 14%, and 35% of these infections, respectively (P < 0.001). Extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E; n = 43) was the main multiresistant organism identified, followed by Pseudomonas aeruginosa (n = 17), methicillin-resistant Staphylococcus aureus (n = 14), and Enterococcus faecium (n = 14). The efficacy of currently recommended empirical antibiotic therapy was very low in nosocomial infections (40%), compared to HCA and CA episodes (73% and 83%, respectively; P < 0.0001), particularly in spontaneous bacterial peritonitis, urinary tract infection, and pneumonia (26%, 29%, and 44%, respectively). Septic shock (26% versus 10%; P < 0.0001) and mortality rate (25% versus 12%; P = 0.001) were significantly higher in infections caused by multiresistant strains. Nosocomial origin of infection (hazard ratio [HR], 4.43), long-term norfloxacin prophylaxis (HR, 2.69), recent infection by multiresistant bacteria (HR, 2.45), and recent use of ß-lactams (HR, 2.39) were independently associated with the development of multiresistant infections. Results in the second series were similar to those observed in the first series. CONCLUSIONS: Multiresistant bacteria, especially ESBL-producing Enterobacteriaceae, are frequently isolated in nosocomial and, to a lesser extent, HCA infections in cirrhosis, rendering third-generation cephalosporins clinically ineffective. New antibiotic strategies tailored according to the local epidemiological patterns are needed for the empirical treatment of nosocomial infections in cirrhosis.

Taxonomy and chemically semi-defined media for the analysis of the tacrolimus producer 'Streptomyces tsukubaensis'.

'Streptomyces tsukubaensis' was the first tacrolimus producer strain identified. Although it has been included in the Streptomyces genus, its taxonomic position has not been rigorously determined. By using a polyphasic approach, we have established that the tacrolimus producer strain 'S. tsukubaensis' NRRL 18488 represents a unique species in the Streptomyces genus, which is phylogenetically distant from other subsequently described producers. This fact means a horizontal transference of the tacrolimus-producing gene cluster. Physiology, nutrient requirement, and molecular genetics analyses of tacrolimus biosynthesis in 'S. tsukubaensis' necessitate chemically defined or semi-defined media, which work as a jigsaw puzzle and allow for pieces (nutrients) exchange. To date, studies related to 'S. tsukubaensis' have been mainly focused in the improvement of tacrolimus production using complex industrial fermentation media, which difficulty allows testing of tacrolimus overproduction enhancers or inhibitors because of the presence of non-defined substances. In the present work, two semi-defined media were developed in order to study the main factors involved in tacrolimus production in 'S. tsukubaensis'.

Relationship between the Synthesis Method and the Magnetoelectric Properties of Bismuth Sodium-Potassium Titanate/Nickel Cobalt Ferrite Lead-Free Composites.

In this work, the influence of the synthesis methods of piezoelectric and magnetostrictive phases on the final properties of the Bi0.5(Na0.8K0.2)0.5TiO3-Ni0.5Co0.5Fe2O4 composites was studied. Different routes were used to individually synthesize each phase, and the composites were prepared using different fractions for each phase. Composites were sintered, and the structural, microstructural, dielectric, and magnetoelectric properties were evaluated. According to the selected synthesis method employed for each phase, different particle sizes and reactivities of the individual phases were obtained. These differences determined the suitable sintering temperature for each set of composites and were responsible for the final properties. In fact, magnetoelectric properties were modulated by the combination of composition and synthesis routes.

Draft genome of Streptomyces tsukubaensis NRRL 18488, the producer of the clinically important immunosuppressant tacrolimus (FK506).

The macrocyclic polyketide tacrolimus (FK506) is a potent immunosuppressant that prevents T-cell proliferation produced solely by Streptomyces species. We report here the first draft genome sequence of a true FK506 producer, Streptomyces tsukubaensis NRRL 18488, the first tacrolimus-producing strain that was isolated and that contains the full tacrolimus biosynthesis gene cluster.

FK506 biosynthesis is regulated by two positive regulatory elements in Streptomyces tsukubaensis.

BACKGROUND: FK506 (Tacrolimus) is an important immunosuppressant, produced by industrial biosynthetic processes using various Streptomyces species. Considering the complex structure of FK506, it is reasonable to expect complex regulatory networks controlling its biosynthesis. Regulatory elements, present in gene clusters can have a profound influence on the final yield of target product and can play an important role in development of industrial bioprocesses. RESULTS: Three putative regulatory elements, namely fkbR, belonging to the LysR-type family, fkbN, a large ATP-binding regulator of the LuxR family (LAL-type) and allN, a homologue of AsnC family regulatory proteins, were identified in the FK506 gene cluster from Streptomyces tsukubaensis NRRL 18488, a progenitor of industrial strains used for production of FK506. Inactivation of fkbN caused a complete disruption of FK506 biosynthesis, while inactivation of fkbR resulted in about 80% reduction of FK506 yield. No functional role in the regulation of the FK506 gene cluster has been observed for the allN gene. Using RT-PCR and a reporter system based on a chalcone synthase rppA, we demonstrated, that in the wild type as well as in fkbN- and fkbR-inactivated strains, fkbR is transcribed in all stages of cultivation, even before the onset of FK506 production, whereas fkbN expression is initiated approximately with the initiation of FK506 production. Surprisingly, inactivation of fkbN (or fkbR) does not abolish the transcription of the genes in the FK506 gene cluster in general, but may reduce expression of some of the tested biosynthetic genes. Finally, introduction of a second copy of the fkbR or fkbN genes under the control of the strong ermE* promoter into the wild type strain resulted in 30% and 55% of yield improvement, respectively. CONCLUSIONS: Our results clearly demonstrate the positive regulatory role of fkbR and fkbN genes in FK506 biosynthesis in S. tsukubaensis NRRL 18488. We have shown that regulatory mechanisms can differ substantially from other, even apparently closely similar FK506-producing strains, reported in literature. Finally, we have demonstrated the potential of these genetically modified strains of S. tsukubaensis for improving the yield of fermentative processes for production of FK506.

The RNA polymerase omega factor RpoZ is regulated by PhoP and has an important role in antibiotic biosynthesis and morphological differentiation in Streptomyces coelicolor.

The RNA polymerase (RNAP) omega factor (ω) forms a complex with the α2ßß' core of this enzyme in bacteria. We have characterized the rpoZ gene of Streptomyces coelicolor, which encodes a small protein (90 amino acids) identified as the omega factor. Deletion of the rpoZ gene resulted in strains with a slightly reduced growth rate, although they were still able to sporulate. The biosynthesis of actinorhodin and, particularly, that of undecylprodigiosin were drastically reduced in the ΔrpoZ strain, suggesting that expression of these secondary metabolite biosynthetic genes is dependent upon the presence of RpoZ in the RNAP complex. Complementation of the ΔrpoZ mutant with the wild-type rpoZ allele restored both phenotype and antibiotic production. Interestingly, the rpoZ gene contains a PHO box in its promoter region. DNA binding assays showed that the phosphate response regulator PhoP binds to such a region. Since luciferase reporter studies showed that rpoZ promoter activity was increased in a ΔphoP background, it can be concluded that rpoZ is controlled negatively by PhoP, thus connecting phosphate depletion regulation with antibiotic production and morphological differentiation in Streptomyces.

Streptomyces tacrolimicus sp. nov., a low producer of the immunosuppressant tacrolimus (FK506).

The number of tacrolimus (FK506)-producing isolates has increased remarkably because of the clinical importance of tacrolimus as an immunosuppressant. However, the taxonomy of several of these isolates has not been studied. The taxonomic status of strain ATCC 55098(T), a tacrolimus-producing strain, was determined in this study. The genotypic, phenotypic and chemotaxonomic properties were consistent with the inclusion of strain ATCC 55098(T) in the genus Streptomyces. The 16S rRNA gene sequence of strain ATCC 55098(T) was determined and used to generate phylogenetic trees with corresponding sequences of the most closely related type strains (≥ 98 % 16S rRNA gene sequence similarity) of species of the genus Streptomyces. Strain ATCC 55098(T) formed a distinct phylogenetic branch adjacent to a cluster comprising Streptomyces fulvissimus NBRC 13482(T) and Streptomyces flavofungini NBRC 13371(T). However, morphological and physiological tests and DNA-DNA relatedness distinguished strain ATCC 55098(T) from its closest phylogenetic neighbours. On the basis of these results, strain ATCC 55098(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces tacrolimicus sp. nov. is proposed. The type strain is ATCC 55098(T) ( = CECT 7664(T)).

Characterisation of a γ-butyrolactone receptor of Streptomyces tacrolimicus: effect on sporulation and tacrolimus biosynthesis.

Streptomyces tacrolimicus (ATCC 55098) was reported to produce the immunosuppressant tacrolimus. The wild-type strain sporulates sparsely and produces very low levels of this immunosuppressant. The lack of genetic knowledge of this strain has hampered strain improvement. In this work, we have cloned the gene encoding a γ-butyrolactone receptor protein (Gbr). The gbr gene is linked to two genes encoding two subunits of the dihydroxyacetone kinase, putatively involved in the biosynthesis of the dihydroxyacetone phosphate precursor of γ-butyrolactone but is not flanked by γ-butyrolactone synthetase genes. The Gbr protein was overexpressed in Escherichia coli and purified. Electrophoretic mobility shift assays showed that Gbr binds to a specific autoregulatory element sequence located 338 bp upstream of the gbr gene, indicating that its expression is self-regulated. The deletion mutant Δgbr showed a very early and intense sporulation in two different media. A phenotype similar to that of the wild-type strain was restored by complementation of the Δgbr mutant with a wild-type gbr allele. Duplication of the gbr gene resulted in a slower sporulation. The Δgbr mutant produced much lower amount (32%) of tacrolimus quantified by high performance liquid chromatography. This analysis, using an optimised system, allowed the resolution of tacrolimus from ascomycin and other contaminant metabolites. Our results indicate that the Gbr protein regulates negatively the sporulation and positively the production of tacrolimus.

"Be Careful What You Swallow": A Case Series of Swallow Syncope.

Swallow (deglutition) syncope is a rare form of neurally mediated cardioinhibitory reflex syncope occurring during swallowing. Patients may present to clinicians across multiple disciplines, so high awareness and careful evaluation are essential. We report 3 such individuals, describing our strategies in diagnosis, investigation and treatment, particularly focusing on conservative management. (Level of Difficulty: Intermediate.).

Sourdough Biotechnology Applied to Gluten-Free Baked Goods: Rescuing the Tradition.

Recent studies suggest that the beneficial properties provided by sourdough fermentation may be translated to the development of new GF products that could improve their technological and nutritional properties. The main objective of this manuscript is to review the current evidence regarding the elaboration of GF baked goods, and to present the latest knowledge about the so-called sourdough biotechnology. A bibliographic search of articles published in the last 12 years has been carried out. It is common to use additives, such as hydrocolloids, proteins, enzymes, and emulsifiers, to technologically improve GF products. Sourdough is a mixture of flour and water fermented by an ecosystem of lactic acid bacteria (LAB) and yeasts that provide technological and nutritional improvements to the bakery products. LAB-synthesized biopolymers can mimic gluten molecules. Sourdough biotechnology is an ecological and cost-effective technology with great potential in the field of GF products. Further research is necessary to optimize the process and select species of microorganisms robust enough to be competitive in any circumstance.