Outcomes of renal replacement therapy in the critically ill with COVID-19.

OBJECTIVE: To describe outcomes of critically ill patients with COVID-19, particularly the association of renal replacement therapy to mortality. DESIGN: A single-center prospective observational study was carried out. SETTING: ICU of a tertiary care center. PATIENTS: Consecutive adults with COVID-19 admitted to the ICU. INTERVENTION: Renal replacement therapy. MAIN VARIABLES OF INTEREST: Demographic data, medical history, illness severity, type of oxygen therapy, laboratory data and use of renal replacement therapy to generate a logistic regression model describing independent risk factors for mortality. RESULTS: Of the total of 166 patients, 51% were mechanically ventilated and 26% required renal replacement therapy. The overall hospital mortality rate was 36%, versus 56% for those requiring renal replacement therapy, and 68% for those with both mechanical ventilation and renal replacement therapy. The logistic regression model identified four independent risk factors for mortality: age (adjusted OR 2.8 [95% CI 1.8-4.4] for every 10-year increase), mechanical ventilation (4.2 [1.7-10.6]), need for continuous venovenous hemofiltration (2.3 [1.3-4.0]) and C-reactive protein (1.1 [1.0-1.2] for every 10 mg/L increase). CONCLUSIONS: In our cohort, acute kidney injury requiring renal replacement therapy was associated to a high mortality rate similar to that associated to the need for mechanical ventilation, while multiorgan failure necessitating both techniques implied an extremely high mortality risk.

OBJETIVO: Describir los resultados de pacientes críticamente enfermos con COVID-19, especialmente la asociación de la terapia de reemplazo renal con la mortalidad. DISEÑO: Estudio observacional, prospectivo y unicéntrico. ÁMBITO: En la unidad de cuidados intensivos (UCI) de un centro de atención terciaria. PACIENTES: Pacientes adultos con COVID-19 ingresados de forma consecutiva en la UCI. INTERVENCIÓN: Administración de terapia de reemplazo renal. VARIABLES DE INTERÉS PRINCIPALES: Datos demográficos, antecedentes médicos, gravedad de la enfermedad, tipo de oxigenoterapia, datos analíticos y uso de terapia de reemplazo renal para generar un modelo de regresión logística que describa factores de riesgo independientes de la mortalidad. RESULTADOS: De los 166 pacientes, el 51% recibieron ventilación mecánica (VM) y el 26% requirió terapia de reemplazo renal (TRR). La mortalidad hospitalaria global fue del 36%, frente al 56% en el caso de los pacientes que requirieron TRR y el 68% en el subconjunto de pacientes que necesitó tanto VM como RTT. Un modelo de regresión logística señala cuatro factores de riesgo independientes de la mortalidad: edad (OR ajustada: 2,8 [IC del 95%: 1,8-4,4] por cada incremento de 10 años), ventilación mecánica (4,2 [1,7-10,6]), necesidad de hemofiltración venovenosa continua (HVVC) (2,3 [1,3-4,0]), y proteína C reactiva (1,1 [1,0-1,2] por cada incremento de 10 mg/L). CONCLUSIONES: En nuestra cohorte, la lesión renal aguda que necesita TRR se asocia con una mortalidad similarmente elevada a la de los pacientes que requieren VM, y la insuficiencia multiorgánica que hace necesarias ambas intervenciones se asocia con un riesgo de mortalidad extremadamente alta.

Outcomes of renal replacement therapy in the critically ill with COVID-19 / Resultados de la terapia de reemplazo renal en pacientes críticamente enfermos con COVID-19

Objective To describe outcomes of critically ill patients with COVID-19, particularly the association of renal replacement therapy to mortality. Design A single-center prospective observational study was carried out. Setting ICU of a tertiary care center. Patients Consecutive adults with COVID-19 admitted to the ICU. Intervention Renal replacement therapy. Main variables of interest Demographic data, medical history, illness severity, type of oxygen therapy, laboratory data and use of renal replacement therapy to generate a logistic regression model describing independent risk factors for mortality. Results Of the total of 166 patients, 51% were mechanically ventilated and 26% required renal replacement therapy. The overall hospital mortality rate was 36%, versus 56% for those requiring renal replacement therapy, and 68% for those with both mechanical ventilation and renal replacement therapy. The logistic regression model identified four independent risk factors for mortality: age (adjusted OR 2.8 [95% CI 1.8–4.4] for every 10-year increase), mechanical ventilation (4.2 [1.7–10.6]), need for continuous venovenous hemofiltration (2.3 [1.3–4.0]) and C-reactive protein (1.1 [1.0–1.2] for every 10mg/L increase). Conclusions In our cohort, acute kidney injury requiring renal replacement therapy was associated to a high mortality rate similar to that associated to the need for mechanical ventilation, while multiorgan failure necessitating both techniques implied an extremely high mortality risk. (AU)

Objetivo Describir los resultados de pacientes críticamente enfermos con COVID-19, especialmente la asociación de la terapia de reemplazo renal con la mortalidad. Diseño Estudio observacional, prospectivo y unicéntrico. Ámbito En la unidad de cuidados intensivos (UCI) de un centro de atención terciaria. Pacientes Pacientes adultos con COVID-19 ingresados de forma consecutiva en la UCI. Intervención Administración de terapia de reemplazo renal. Variables de interés principales Datos demográficos, antecedentes médicos, gravedad de la enfermedad, tipo de oxigenoterapia, datos analíticos y uso de terapia de reemplazo renal para generar un modelo de regresión logística que describa factores de riesgo independientes de la mortalidad. Resultados De los 166 pacientes, el 51% recibieron ventilación mecánica (VM) y el 26% requirió terapia de reemplazo renal (TRR). La mortalidad hospitalaria global fue del 36%, frente al 56% en el caso de los pacientes que requirieron TRR y el 68% en el subconjunto de pacientes que necesitó tanto VM como RTT. Un modelo de regresión logística señala cuatro factores de riesgo independientes de la mortalidad: edad (OR ajustada: 2,8 [IC del 95%: 1,8-4,4] por cada incremento de 10 años), ventilación mecánica (4,2 [1,7-10,6]), necesidad de hemofiltración venovenosa continua (HVVC) (2,3 [1,3-4,0]), y proteína C reactiva (1,1 [1,0-1,2] por cada incremento de 10mg/L). Conclusiones En nuestra cohorte, la lesión renal aguda que necesita TRR se asocia con una mortalidad similarmente elevada a la de los pacientes que requieren VM, y la insuficiencia multiorgánica que hace necesarias ambas intervenciones se asocia con un riesgo de mortalidad extremadamente alta. (Au)

Outcomes of renal replacement therapy in the critically ill with COVID-19.

OBJECTIVE: To describe outcomes of critically ill patients with COVID-19, particularly the association of renal replacement therapy to mortality. DESIGN: A single-center prospective observational study was carried out. SETTING: ICU of a tertiary care center. PATIENTS: Consecutive adults with COVID-19 admitted to the ICU. INTERVENTION: Renal replacement therapy. MAIN VARIABLES OF INTEREST: Demographic data, medical history, illness severity, type of oxygen therapy, laboratory data and use of renal replacement therapy to generate a logistic regression model describing independent risk factors for mortality. RESULTS: Of the total of 166 patients, 51% were mechanically ventilated and 26% required renal replacement therapy. The overall hospital mortality rate was 36%, versus 56% for those requiring renal replacement therapy, and 68% for those with both mechanical ventilation and renal replacement therapy. The logistic regression model identified four independent risk factors for mortality: age (adjusted OR 2.8 [95% CI 1.8-4.4] for every 10-year increase), mechanical ventilation (4.2 [1.7-10.6]), need for continuous venovenous hemofiltration (2.3 [1.3-4.0]) and C-reactive protein (1.1 [1.0-1.2] for every 10mg/L increase). CONCLUSIONS: In our cohort, acute kidney injury requiring renal replacement therapy was associated to a high mortality rate similar to that associated to the need for mechanical ventilation, while multiorgan failure necessitating both techniques implied an extremely high mortality risk.

An Innovative Root Inoculation Method to Study Ralstonia solanacearum Pathogenicity in Tomato Seedlings.

In this study, we report Ralstonia solanacearum pathogenicity in the early stages of tomato seedlings by an innovative root inoculation method. Pathogenicity assays were performed under gnotobiotic conditions in microfuge tubes by employing only 6- to 7-day-old tomato seedlings for root inoculation. Tomato seedlings inoculated by this method exhibited the wilted symptom within 48 h and the virulence assay can be completed in 2 weeks. Colonization of the wilted seedlings by R. solanacearum was confirmed by using gus staining as well as fluorescence microscopy. Using this method, mutants in different virulence genes such as hrpB, phcA, and pilT could be clearly distinguished from wild-type R. solanacearum. The method described here is economic in terms of space, labor, and cost as well as the required quantity of bacterial inoculum. Thus, the newly developed assay is an easy and useful approach for investigating virulence functions of the pathogen at the seedling stage of hosts, and infection under these conditions appears to require pathogenicity mechanisms used by the pathogen for infection of adult plants.

Ring expansion of oxyglycals. Synthesis and conformational analysis of septanoside-containing trisaccharides.

Oxyglycals, derived from lactose and maltose, were expanded to trisaccharides through a ring expansion method. Trisaccharides with 6-7-5 and 6-7-6 ring sizes were prepared through the ring expansion method, with high diastereoselectivities, in each step of their synthesis. The NOE and ROESY NMR spectroscopies were used to assess the dipolar couplings within the trisaccharide. A computational study was undertaken, from which low energy conformations, as well as, dihedral angles that define the glycosidic linkages were identified.

Pigment and virulence deficiencies associated with mutations in the aroE gene of Xanthomonas oryzae pv. oryzae.

Xanthomonadins are yellow, membrane-bound pigments produced by members of the genus Xanthomonas. We identified an ethyl methanesulfonate-induced Xanthomonas oryzae pv. oryzae mutant (BXO65) that is deficient for xanthomonadin production and virulence on rice, as well as auxotrophic for aromatic amino acids (Pig(-) Vir(-) Aro(-)). Reversion analysis indicated that these multiple phenotypes are due to a single mutation. A genomic library of the wild-type strain was used to isolate a 7.0-kb clone that complements BXO65. By transposon mutagenesis, marker exchange, sequence analysis, and subcloning, the complementing activity was localized to a 849-bp open reading frame (ORF). This ORF is homologous to the aroE gene, which encodes shikimate dehydrogenase in various bacterial species. Shikimate dehydrogenase activity was present in the wild-type strain and the mutant with the complementing clone, whereas no activity was found in BXO65. This clone also complemented an Escherichia coli aroE mutant for prototrophy, indicating that aroE is functionally conserved in X. oryzae pv. oryzae and E. coli. The nucleotide sequence of the 2.9-kb region containing aroE revealed that a putative DNA helicase gene is located adjacent to aroE. Our results indicate that aroE is required for normal levels of virulence and xanthomonadin production in X. oryzae pv. oryzae.

Novel genomic locus with atypical G+C content that is required for extracellular polysaccharide production and virulence in Xanthomonas oryzae pv. oryzae.

Three exopolysaccharide (EPS)- and virulence-deficient mutants of Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight of rice, were isolated by Tn5 mutagenesis. These insertions are not located within the gum gene cluster. A 40-kb cosmid clone that restored EPS production and virulence to all three mutants was isolated, and the three transposon insertions were localized to contiguous 4.3- and 3.5-kb EcoRI fragments that are included in this clone. Sequence data indicate that two of the transposon insertions are in genes that encode a putative sugar nucleotide epimerase and a putative glycosyl transferase, respectively; the third insertion is located between the glycosyl transferase gene and a novel open reading frame (ORF). A 5.5-kb genomic region in which these three ORFs are located has a G+C content of 5-1.7%, quite different from the G+C content of approximately 65.0% that is typical of X. oryzae pv. oryzae. Homologues of this locus have not yet been reported in any other xanthomonad.

Stationary-phase variation due to transposition of novel insertion elements in Xanthomonas oryzae pv. oryzae.

Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. Spontaneous mutants which are deficient for virulence and extracellular polysaccharide (Eps) production accumulate in large numbers in stationary-phase cultures of this bacterium, a phenomenon which we have called stationary-phase variation. A clone (pSD1) carrying the Eps biosynthetic gene (gum) cluster of X. oryzae pv. oryzae restored Eps production and virulence to several spv (for stationary-phase variation) mutants. Data from localized recombination analysis, Southern hybridization, PCR amplification, and sequence analysis showed that the mutations are due to insertion of either one of two novel endogenous insertion sequence (IS) elements, namely, ISXo1 and ISXo2, into gumM, the last gene of the gum gene cluster. The results of Southern analysis indicate the presence of multiple copies of both IS elements in the genome of X. oryzae pv. oryzae. These results demonstrate the role of IS elements in stationary-phase variation in X. oryzae pv. oryzae.

Mutants of Xanthomonas oryzae pv. oryzae deficient in general secretory pathway are virulence deficient and unable to secrete xylanase.

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight, a serious disease of rice. A virulence- and xylanase-deficient mutant of Xoo was isolated following ethyl methane sulfonate (EMS) mutagenesis. A cosmid clone that restored virulence and xylanase secretion was obtained from a genomic library by functional complementation. Transposon mutagenesis and marker exchange studies revealed genes on the cloned DNA that were required for xylanase production and virulence. Sequence analysis with transposon-specific primers revealed that these genes were homologues of xps F and xps D, which encode components of a protein secretion system in Xanthomonas campestris pv. campestris. Enzyme assays showed xylanase accumulation in the periplasmic space and cytoplasm of the xps F mutant and the complementing clone restored transport to the extracellular space.

A transposon insertion in the gumG homologue of Xanthomonas oryzae pv. oryzae causes loss of extracellular polysaccharide production and virulence.

Xanthomonas oryzae pv. oryzae causes a serious disease of rice called bacterial leaf blight. It produces copious amounts of extracellular polysaccharide (EPS). An EPS- and virulence-deficient mutant of X. oryzae pv. oryzae was isolated by Tn5 mutagenesis. The mutant allele in this strain was cloned by transposon tagging in the Escherichia coli vector pBluescript and the DNA sequences flanking the transposon insertion site were determined. Computer-based similarity searches in the DNA database using the BLAST algorithm showed these sequences to be 78% identical at the nucleotide level to a gene, gumG, in the gum cluster, which is required for EPS biosynthesis in Xanthomonas campestris pv. campestris. A 36-kb X. oryzae pv. oryzae genomic clone containing the putative EPS biosynthetic gene cluster of X. oryzae pv. oryzae restored both EPS production and virulence proficiency to the gumGXo::Tn5 mutant. The results suggest that EPS is an important virulence factor of X. oryzae pv. oryzae.

The bacterial pigment xanthomonadin offers protection against photodamage.

Xanthomonas oryzae pv. oryzae is a bacterial pathogen that causes leaf blight, a serious disease of rice. Most members of the genus Xanthomonas produce yellow, membrane bound, brominated aryl polyene pigments called xanthomonadins whose functional role is unclear. We find that pigment-deficient mutants of X. oryzae pv. oryzae exhibit hypersensitivity to photobiological damage. A clone containing the xanthomonadin biosynthetic gene cluster alleviates the hypersensitivity of the pigment-deficient mutant. Extracts containing xanthomonadin provide protection against photodynamic lipid peroxidation in liposomes. These results lead us to suggest a role for the pigment, namely protection against photodamage.

Genetic Diversity within the Population of Xanthomonas oryzae pv. oryzae in India.

ABSTRACT Xanthomonas oryzae pathovar oryzae causes a serious disease of rice in India and is endemic in all of the major rice-growing areas of the country. Sixty-seven X. oryzae pv. oryzae strains, collected mostly in 1994 and 1995, from 18 locations in India were analyzed by DNA fingerprinting methods using two separate repeat element probes from the X. oryzae pv. oryzae genome. These results show that strains belonging to a single pathogen lineage can be isolated from 16 of the 18 locations sampled; many of these locations are separated from each other by hundreds of kilometers and represent ecologically diverse rice-growing areas. Pathotyping analysis indicated that the strains in this lineage belong to pathotype 1b of X. oryzae pv. oryzae.

Arabidopsis mutants deficient in T-DNA integration.

Arabidopsis thaliana mutants originally isolated as hypersensitive to irradiation were screened for the ability to be transformed by Agrobacterium transferred DNA (T-DNA). One of four UV-hypersensitive mutants and one of two gamma-hypersensitive mutants tested showed a significant reduction in the frequency of stable transformants compared with radioresistant controls. In a transient assay for T-DNA transfer independent of genomic integration, both mutant lines took up and expressed T-DNA as efficiently as parental lines. These lines are therefore deficient specifically in stable T-DNA integration and thus provide direct evidence for the role of a plant function in that process. As radiation hypersensitivity suggests a deficiency in repair of DNA damage, that plant function may be one that is also involved in DNA repair, possibly, from other evidence, in repair of double-strand DNA breaks.

Activity of the yeast FLP recombinase in Arabidopsis.

The coding sequence for FLP recombinase, originally from the 2 mu plasmid of Saccharomyces cerevisiae, was introduced into Arabidopsis behind the cauliflower mosaic virus 35S promoter. FLP activity was monitored by the glucuronidase activity resulting from inversion of an antisense-oriented GUS reporter gene flanked by a pair of FRT target sites in inverted repeat. FLP-dependent Gus activity was observed in both transient assays and transgenic plants. The FLP system will be useful for a variety of in planta genetic manipulations.

Lethal transposition of Mud phages in Rec- strains of Salmonella typhimurium.

Under several circumstances, the frequency with which Mud prophages form lysogens is apparently reduced in rec strains of Salmonella typhimurium. Lysogen formation by a MudI genome (37 kb) injected by a Mu virion is unaffected by a host rec mutation. However when the same MudI phage is injected by a phage P22 virion, lysogeny is reduced in a recA or recB mutant host. A host rec mutation reduces the lysogenization of mini-Mu phages injected by either Mu or P22 virions. When lysogen frequency is reduced by a host rec mutation, the surviving lysogens show an increased probability of carrying a deletion adjacent to the Mud insertion site. We propose that the rec effects seen are due to a failure of conservative Mu transposition. Replicative Mud transposition from a linear fragment causes a break in the host chromosome with a Mu prophage at both broken ends. These breaks are lethal unless repaired; repair can be achieved by Rec functions acting on the repeated Mu sequences or by secondary transposition events. In a normal Mu infection, the initial transposition from the injected fragment is conservative and does not break the chromosome. To account for the conditions under which rec effects are seen, we propose that conservative transposition of Mu depends on a protein that must be injected with the DNA. This protein can be injected by Mu but not by P22 virions. Injection or function of the protein may depend on its association with a particular Mu DNA sequence that is present and properly positioned in Mu capsids containing full-sized Mu or MudI genomes; this sequence may be lacking or abnormally positioned in the mini-Mud phages tested.

Role of gene duplications in the adaptation of Salmonella typhimurium to growth on limiting carbon sources.

Duplication-containing cells are selected when growth of Salmonella typhimurium is limited by the availability of any one of several carbon and energy sources. Under conditions of extreme starvation, growth occurs almost exclusively in the duplication-containing fraction of the population. Cells with duplications of one large segment of the chromosome are repeatedly selected regardless of which of these carbon sources limits growth. The duplicated chromosomal segment encodes the transport systems for all of these carbon sources. This duplication is not selected during growth on a carbon source for which the permease is not included within the duplication segment. This suggests that the growth advantage conferred by the duplication may be due to increased transport of the limiting carbon source. Inclusion of the permease alone is not sufficient to explain the growth advantage of the duplications, since other common duplications that include the permease are not selected.