The two-component system ActJK is involved in acid stress tolerance and symbiosis in Sinorhizobium meliloti.

The nitrogen-fixing α-proteobacterium Sinorhizobium meliloti genome codifies at least 50 response regulator (RR) proteins mediating different and, in many cases, unknown processes. RR-mutant library screening allowed us to identify genes potentially implicated in survival to acid conditions. actJ mutation resulted in a strain with reduced growth rate under mildly acidic conditions as well as a lower capacity to tolerate a sudden shift to lethal acidic conditions compared with the parental strain. Mutation of the downstream gene actK, which encodes for a histidine kinase, showed a similar phenotype in acidic environments suggesting a functional two-component system. Interestingly, even though nodulation kinetics, quantity, and macroscopic morphology of Medicago sativa nodules were not affected in actJ and actK mutants, ActK was required to express the wild-type nitrogen fixation phenotype and ActJK was necessary for full bacteroid development and nodule occupancy. The actJK regulatory system presented here provides insights into an evolutionary process in rhizobium adaptation to acidic environments and suggests that actJK-controlled functions are crucial for optimal symbiosis development.

Mesorhizobium sanjuanii sp. nov., isolated from nodules of Lotus tenuis in the saline-alkaline lowlands of Flooding Pampa, Argentina.

Two rhizobial strains, BSA136T and BSA150, related to the genus Mesorhizobium were isolated from root nodules of Lotus tenuis grown in saline-alkaline lowlands soil from Argentina. These strains showed different repetitive element palindromic PCR fingerprinting patterns but shared more than 99 % sequence similarity for both 16S rRNA and recA genes. Despite the symbiotic nodC gene sequences of our strains being related to the canonical Lotus biovar species comprising Mesorhizobium loti and Mesorhizobium japonicum, the 16S rRNA phylogenetic marker suggests that their taxonomical identities are closely related to Mesorhizobium helmanticense, Mesorhizobium metallidurans, Mesorhizobium thianshanense, Mesorhizobium gobiense and Mesorhizobium tarimense. Multilocus sequence analysis performed with seven housekeeping genes confirmed that BSA136T belongs to a separate clade within the genus Mesorhizobium. The results of comparisons for in silico DNA-DNA hybridization and average nucleotide identity indexes between the genomes of BSA136T and closest-related Mesorhizobium species were below the threshold for species delineation. Phenotypic features differentiated BSA136T from its closest-related species. On the basis of our results, BSA136T and BSA150 can be considered to represent a novel species of the genus Mesorhizobium, for which the name Mesorhizobium sanjuanii sp. nov. is hereby proposed. The type strain of this species is BSA136T (=CECT 9305T=LMG 30060T), for which the draft genome sequence is available.

A consolidated analysis of the physiologic and molecular responses induced under acid stress in the legume-symbiont model-soil bacterium Sinorhizobium meliloti.

Abiotic stresses in general and extracellular acidity in particular disturb and limit nitrogen-fixing symbioses between rhizobia and their host legumes. Except for valuable molecular-biological studies on different rhizobia, no consolidated models have been formulated to describe the central physiologic changes that occur in acid-stressed bacteria. We present here an integrated analysis entailing the main cultural, metabolic, and molecular responses of the model bacterium Sinorhizobium meliloti growing under controlled acid stress in a chemostat. A stepwise extracellular acidification of the culture medium had indicated that S. meliloti stopped growing at ca. pH 6.0-6.1. Under such stress the rhizobia increased the O2 consumption per cell by more than 5-fold. This phenotype, together with an increase in the transcripts for several membrane cytochromes, entails a higher aerobic-respiration rate in the acid-stressed rhizobia. Multivariate analysis of global metabolome data served to unequivocally correlate specific-metabolite profiles with the extracellular pH, showing that at low pH the pentose-phosphate pathway exhibited increases in several transcripts, enzymes, and metabolites. Further analyses should be focused on the time course of the observed changes, its associated intracellular signaling, and on the comparison with the changes that operate during the sub lethal acid-adaptive response (ATR) in rhizobia.

Eventración diafragmática congénita: causa infrecuente de dificultad respiratoria / Congenital diaphragmatic eventration: Rare cause of respiratory distress

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Altered plasma concentrations of sex hormones in cats infected by feline immunodeficiency virus or feline leukemia virus.

Gender differences may affect human immunodeficiency virus (HIV) infection in humans and may be related to fluctuations in sex hormone concentration. The different percentage of male and female cats observed to be infected by feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV) has been traditionally explained through the transmission mechanisms of both viruses. However, sexual hormones may also play a role in this different distribution. To study this possibility, 17ß-estradiol, progesterone, testosterone, and dehydroepiandrosterone (DHEA) concentrations were analyzed using a competitive enzyme immunoassay in the plasma of 258 cats naturally infected by FIV (FIV(+)), FeLV (FeLV(+)), or FeLV and FIV (F(-)F(+)) or negative for both viruses, including both sick and clinically healthy animals. Results indicated that the concentrations of 17ß-estradiol and testosterone were significantly higher in animals infected with FIV or FeLV (P < 0.05) than in negative cats. Plasma concentrations of DHEA in cats infected by either retrovirus were lower than in negative animals (P < 0.05), and F(-)F(+) cats had significantly lower plasma values than monoinfected cats (P < 0.05). No significant differences were detected in the plasma concentration of progesterone of the four groups. No relevant differences were detected in the hormone concentrations between animal genders, except that FIV(+) females had higher DHEA concentrations than the corresponding males (P < 0.05). In addition, no differences were observed in the hormone concentrations between retrovirus-infected and noninfected animals with and without clinical signs. These results suggest that FIV and FeLV infections are associated with an important deregulation of steroids, possibly from early in the infection process, which might have decisive consequences for disease progression.

Úlcera rectal solitaria como causa infrecuente de rectorragia / Solitary rectal ulcer syndrome as a rare cause of rectal bleeding

La úlcera rectal solitaria es un trastorno crónico, benigno, excepcional en pediatría, caracterizado por un conjunto de síntomas, como tenesmo, dolor perianal y prolapso rectal ocasional, con unos hallazgos anatomopatológicos típicos. La histología pone de manifiesto un engrosamiento de la mucosa y la muscularis mucosae, la elongación y distorsión de las glándulas, un edema de la lámina propia y, a veces, una ulceración de la lesión. Las lesiones se localizan con frecuencia en la pared anterior del recto, y la ulceración no siempre está presente. El diagnóstico suele ser tardío, dada la inespecificidad y la variabilidad clínica, y se basa en los estudios endoscópicos e histológicos. Aunque se trata de una entidad bien conocida en la edad adulta, resulta inusual en pediatría. Presentamos el caso de un adolescente de 16 años diagnosticado 4 años después del inicio de los síntomas(AU)

Solitary rectal ulcer syndrome is a rare condition in children, with benign chronic curse that is characterised by a complex of clinical and histological features. It usually appears with rectal bleeding, tenesmus and perinial pain, occasional rectal prolapsed and typical anatomopathological findings. Histologically, the presence of thickening of the mucous portion and muscularis mucosae, elongation and distortion of the glands and edema of the lamina propria and occasionally, ulceration of the lesion. The lesions are most often located on the anterior wall of the rectum, and ulceration is not always present. The diagnosis is usually delayed due to the nonspecific and clinical variability and is based on samples obtained by colonoscopy and biopsy. Although this entity is well recognized in adults, there are few pediatric cases reported in literature. We reporta 16 year-old boy case who was diagnosed 4 years after the onset of the symptoms(AU)

Development of new positive-selection RIVET tools: detection of induced promoters by the excision-based transcriptional activation of an aacCI (GmR)-gfp fusion.

RIVET (Recombination Based in vivo Expression Technology) is a powerful genetic tool originally conceived for the identification of genes induced in complex biological niches where conventional transcriptomics is difficult to use. With a broader application, genetic recombination-based technologies have also been used, in combination with regulatory proteins and specific transcriptional regulators, for the development of highly sensitive biosensor systems. RIVET systems generally comprise two modules: a promoter-trap cassette generating genomic transcriptional fusions to the tnpR gene encoding the Tn-γδ TnpR resolvase, and a reporter cassette carrying res-flanked selection markers that are excised upon expression of tnpR to produce an irreversible, inheritable phenotypic change. We report here the construction and validation of a new set of positive-selection RIVET systems that, upon induction of the promoter-trap module, generate the transcriptional activation of an antibiotic-resistant and a green-fluorescent phenotype. Two classes of promoter-trap tools were constructed to generate transcriptional fusions to tnpR: one based on the use of a narrow-host-range plasmid (pRIVET-I), integrative in several Gram-negative bacteria, and the other based on the use of a broad-host-range plasmid (pRIVET-R). The system was evaluated in the model soil bacterium Sinorhizobium meliloti, where a clear-cut phenotypic transition from Nm(R)-Gm(S)-GFP(-) to Nm(S)-Gm(R)-GFP(+) occurred upon expression of tnpR. A S. meliloti integrative RIVET library was constructed in pRIVET-I and, as expected, changes in the extracellular conditions (e.g., salt stress) triggered a significant increase in the appearance of Gm(R)-GFP(+) (excised) clones. The sacB-independent positive-selection RIVET systems here described provide suitable basic tools both for the construction of new recombination-based biosensors and for the search of bacterial markers induced when microorganisms colonize and invade complex environments and eukaryotic hosts.

Plasma electrophoretogram in feline immunodeficiency virus (FIV) and/or feline leukaemia virus (FeLV) infections.

The electrophoretogram of 89 cats, including those infected by feline immunodeficiency virus (FIV+), feline leukaemia virus (FeLV+) and non-infected, showed statistically significant differences in several of the fractions. FIV+ cats had very high protein values (mean, 8.10 g/dl), mostly because of hypergammaglobulinemia (mean, 2.81 g/dl) as compared with non-infected animals and FeLV+. In addition, in these FIV+ animals, the albumin/globulins ratio (A/G) was very low (mean, 0.72). Statistically significant differences in A/G and alpha2-globulin fraction were observed in FeLV+ group (A/G mean, 0.88 +/- 0.08; alpha2-globulin, mean, 0.84 +/- 0.07 g/dl) when compared with non-infected group (A/G mean, 1.06 +/- 0.08; alpha2-globulin mean, 0.68 +/- 0.04 g/dl). The alpha1-globulin fraction was higher in double infected animals (FIV and FeLV positive, F-F) (3.55 g/dl), than in FeLV+ or FIV+ cats (3.10 and 3.07 g/dl respectively), but no statistical conclusions may be drawn from this fact because of the low number of F-F animals. This technique may help to assess the initial clinical status of retrovirus-infected cats, and the clinical course of these chronic diseases, specifically during and after suitable therapy.

Addison disease after appendicitis.

A 14-year-old boy manifested acute abdominal pain, vomiting, high temperature and diarrhea. He also underwent increasing hyponatremia and hyperkalemia after appendectomy. Further testing confirmed Addison disease. The serum adrenal antibody test was positive, and other autoimmune diseases were excluded.

Antenatal diagnosis and management of a ranula.

We describe a case of congenital ranula or retention salivary cyst diagnosed at 26 weeks of gestation. The fetal karyotype was obtained by amniocentesis and chorionic villus sampling, and was normal. Follow-up ultrasound scans revealed no changes in the size or the position of the cyst. Surgical treatment was performed 2 days after a normal vaginal delivery, with excellent results.

Role of endothelium-related mechanisms in the pathophysiology of renal ischemia/reperfusion in normal rabbits.

The present study addressed the effect of interventions aimed to increase NO in the setting of acute renal ischemia/reperfusion (I/R) in uninephrectomized rabbits. In the 60-minute post-I/R period, L-arginine+superoxide (O2.-) dismutase (SOD) synergistically improved the renal functional (69.4% versus 10.4% of the pre-I/R glomerular filtration rate with or without L-arginine+SOD, respectively; p < .01) and histological parameters (82.9% decrease of medullary congestion in L-arginine+SOD, P < .01 versus vehicle) and blocked the I/R-dependent neutrophil accumulation (89.3% reduction). In spite of these results over the short term, a second set of experiments disclosed that the protection by L-arginine+SOD was no longer present at 24 and 48 hours (plasma creatinine in vehicle-treated versus L-arginine+SOD-treated animals [mg/100 mL]: 24 hours after I/R, 9.4 +/- 1.9 versus 8.07 +/- 0.65; 48 hours after I/R, 11.6 +/- 3.6 versus 9.7 +/- 0.9; P = NS in all the cases). Additional experiments were conducted using a milder 30-minute ischemic model, which showed no significant functional or histological protection by using L-arginine+SOD. In conclusion, our experiments disclosed the following: (1) the critical importance of the interaction between NO and O2.- in the acute protective effect of L-arginine (this effect not only improved renal function and histology but also reduced neutrophil accumulation) and (2) the discordance existing between the immediate protection afforded by L-arginine+SOD and the lack of protection observed at 24 and 48 hours. This finding suggests that a punctual intervention on the NO system at the time of I/R is not sufficient to reduce renal damage over the long term.

[An asymptomatic splenic hamartoma treated by conservative surgery]. / Hamartoma esplénico asintomático tratado con cirugía conservadora.

We present the case of an 8-year-old boy accidentally diagnosed of a splenic tumor by ultrasound and computed tomography scan of the abdomen. The patient was treated surgically with a conservative surgical technique (wedge resection and splenorraphy). The histologic study revealed a hamartoma and by immunohistologic study a clear differentiation with the splenic capillary hemangioma could be made.

[Meckel's diverticulum in childhood. Personal experience and actualization]. / El divertículo de Meckel en la infancia. Actualización y experiencia personal.

The authors present 40 cases of Meckel's diverticulum in pediatric patients (average age 6.8 years old). 31 of these (77.5%) were discovered casually in surgery and the other nine (22.5%) presented specific symptoms (three intestinal intussusceptions, three perforations, one hemorrhage, a wet umbilicus and an intestinal obstruction). In this group, seven abdominal radionuclide scan were practiced with 99mTc, resulting in two positive diagnosis (28.5%). All patients were treated with short ileal resection. The histopathological study revealed in nine cases (22.5%) the presence of gastric ectopic mucosa and, in one of them, pancreatic tissue was also found. The only morbidity was a postoperative intestinal obstruction that occurred several months later and that required surgery. The mortality was zero and the average hospital stay was 8.6 days.

[Bleeding intestinal angiodysplasia. Report of a pediatric case]. / Angiodisplasia intestinal sangrante. Aportación de un caso pediátrico.

This report presents a pediatric case of right colic angiodysplasia and perhaps jejunoileal with lethal evolution by the great intensity of bleeding. Are discussed the different etiopathogenesis and the difficulties for the clinicopathological diagnosis and the actual trend towards a conservative treatment (electrocoagulation versus intestinal resection).

[Sequential surgery in familial hyperlipemia. Comments on 2 pediatric cases]. / Cirugía secuencial en la hiperlipemia familiar. Comentarios a dos casos pediátricos.

The present report analyzes two cases of homozygotic familiar hypercholesterolemia. An actualization on the etiopathogenesis, the poor short term prognosis and the bad results obtained with the conservative therapy are discussed. The different surgical approaches excluding liver transplantation are reviewed. Both cases underwent staged portocaval shunts and ileal exclusions afterwards. Short and intermediate results are exposed.