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Biomedical subjects

C Quinto

Publications and source records attributed to C Quinto.

At least 19 recordsLinked to original sources
PubMed2001

Actin monoubiquitylation is induced in plants in response to pathogens and symbionts.

Most dramatic examples of actin reorganization have been described during host-microbe interactions. Plasticity of actin is, in part, due to posttranslational modifications such as phosphorylation or ubiquitylation. Here, we show for the first time that actins found in root nodules of Phaseolus vulgaris are modified transiently during nodule development by monoubiquitylation. This finding was extended to root nodules of other legumes and to other plants infected with mycorrhiza or plant pathogens such as members of the genera Pseudomonas and Phytophthora. However, neither viral infections nor diverse stressful conditions (heat shock, wounding, or osmotic stress) induced this response. Additionally, this phenomenon was mimicked by the addition of a yeast elicitor or H2O2 to Phaseolus vulgaris suspension culture cells. This modification seems to provide increased stability of the microfilaments to proteolytic degradation and seems to be found in fractions in which the actin cytoskeleton is associated with membranes. All together, these data suggest that actin monoubiquitylation may be considered an effector mechanism of a general plant response against microbes.

Actins↗
PubMed2000

Open-ring imaging sign: highly specific for atypical brain demyelination.

OBJECTIVE: To test the specificity for demyelination of a new neuroimaging sign: contrast enhancement shaped as an open ring or a crescent circumscribed to the white matter. BACKGROUND: Brain demyelination can cause ring enhancement mimicking neoplasm or infection on CT or MRI. METHODS: A MEDLINE search of pathology-proved demyelination yielded 32 illustrated cases of ring-enhancing lesions published between 1981 and 1995. Controls consisted of the same number of published images of neoplasms and infections, pathology proved, and matched by year of publication, and age and gender of the patient. Two neuroradiologists read the images twice independently 1 year apart. RESULTS: Interrater agreement was good (kappa = 0.64 and 0.66 for either reading). Test-retest reliability was high (kappa = 0.75 and 0.74 for either rater). The open-ring sign clearly distinguished demyelinating lesions from neoplasms and infections. For demyelination versus neoplasm or infection, the specificity of the reading by the first neuroradiologist was 93.8 (95% CI, 86 to 98), and that of the second was 84.4 (95% CI, 74 to 92). The likelihood ratio of demyelination versus neoplasm averaged 5.2, and versus infection, 17.2. That is, if the lesions had the same incidence in the population, in the presence of an open-ring sign demyelination would be five times more likely than neoplasm and 17 times more likely than infection. However, given the much higher incidence of neoplasms and infections, these lesions are still frequently responsible for open-ring enhancement. CONCLUSIONS: The open-ring sign is often present in large, contrast-enhancing demyelinating lesions and helps to differentiate them from neoplasms and infections.

Adult↗
PubMed2000

Posttraumatic delayed sleep phase syndrome.

Circadian rhythm sleep disorders may occur after traumatic brain injury. We describe a 48-year-old man who presented with sleep onset insomnia and cognitive dysfunction after a car accident. A diagnosis of delayed sleep phase syndrome (DSPS) was confirmed by sleep logs and actigraphy, which revealed sleep onset in the early morning hours and awakening around noon.

Brain Injuries↗
PubMed1999

A rapid-cycling bipolar patient treated with long nights, bedrest, and light.

BACKGROUND: Stabilization of rapid-cycling bipolar disorder is extremely difficult. METHODS: A refractory bipolar I rapid-cycling patient on valproate was treated with long "nights" (extended sleep in darkness) and daytime light therapy. RESULTS: Rapid cycling immediately stopped on initiation of a 10 hour dark/rest period. This was extended to 14 hours (plus a self-selected 1 hour midday nap) without problems. Depression gradually improved when midday light therapy was added; near-euthymia was attained after light therapy was shifted to the morning. CONCLUSIONS: Nonpharmacological chronobiological treatments may be a means to interrupt rapid cycling.

Activity Cycles↗
PubMed1999

Sensitive median-ulnar motor comparative techniques in carpal tunnel syndrome.

We describe two modified methods for median-to-ulnar motor conduction comparison in the diagnosis of median neuropathy at the wrist: the median-thenar to ulnar-thenar latency difference (TTLD), and the median-thenar to ulnar-hypothenar latency difference (THLD). We also describe an F-wave ulnar-to-median comparative test, the F-wave latency difference (FWLD). The abnormal cutoffs based upon 34 normal controls are: TTLD, 0.8 ms; THLD, 1.2 ms; FWLD, 0.6 ms. In 50 patients (79 hands) with clinically defined carpal tunnel syndrome and electrophysiological evidence of median neuropathy at the wrist (based upon a prolonged median nerve palm-wrist latency), the diagnostic sensitivities were: 95-98%, 85-88%, and 75-78%, respectively. These tests are therefore highly sensitive. They are easily performed and require minimal additional effort to incorporate into commonly used clinical electrodiagnostic routines. They may be advantageous when a concomitant polyneuropathy is present, and they may also help avoid technical pitfalls and aid in identification of anatomic variants.

Action Potentials↗
PubMed1999

Biological nitrogen fixation and future challenges of agriculture. The endophytic connection.

Feeding the growing global population, anticipated to be 8 billion by the year 2020, is one of the most important recent challenges of agriculture. The increase in cereal grain yield, to cope with this demand, directly implies a dramatic increase in the use of nitrogen-based fertilizers and agrochemicals. Some of these intensive agricultural practices have progressive detrimental effects on the environment. This review is focused on some novel insights gained into the understanding of associative and symbiotic interactions of plants with nitrogen-fixing organisms that makes Biological Nitrogen Fixation (BNF) a viable answer to this compelling dilemma.

Agriculture↗
PubMed1999

Median and ulnar palm-wrist studies.

OBJECTIVES: Routine carpal tunnel electrodiagnosis frequently includes median (MPW) and ulnar (UPW) palm-wrist mixed nerve conduction latency determinations over 8 cm. Despite widespread use, normative palmar latency difference (PLD) and UPW values, and the relative utility of onset latency (OL) or peak latency (PL) measurements are controversial. The current study was conducted to determine normative values for these parameters. METHODS: MPW and UPW studies were performed unilaterally in 33 normal controls. The PLD-OL and PLD-PL were calculated. The mean, range, standard deviation, and upper limits of normal were determined. 74 hands (50 patients) with both clinical and electrophysiologic median neuropathy were also studied. RESULTS: The abnormal MPW and UPW cut-offs were both 1.8 ms (OL), and 2.3 ms (PL). The abnormal PLD cut-offs were 0.5 ms (OL and PL). Using either OL or PL, PLD parameters were similar within controls, and also within CTS patients. Using either OL or PL, UPW parameters were similar between controls and CTS patients. CONCLUSIONS: An abnormal PLD cut-off of 0.5 is recommended. This is slightly higher than some prior recommendations, however it should minimize the likelihood of false positive studies. Onset and peak latency measurements are likely to have similar clinical utility.

Adult↗
PubMed1999

Rhizobium nod factors induce increases in intracellular free calcium and extracellular calcium influxes in bean root hairs

Application of Nod factors to growing, responsive root hairs of the bean Phaseolus vulgaris induces marked changes in both the intracellular cytosolic free calcium (Ca2+) and in the influx of extracellular [Ca2+]. The intracellular [Ca2+], which has been measured by ratiometric imaging in cells microinjected with fura-2-dextran (70 kDa), elevates within 5 min from approximately 400 nM to 1500 nM in localised zones in the root hair apex. Of particular note is the observation that the elevated regions of [Ca2+] appear to shift position during short time intervals. Increases in and fluctuations of the intracellular [Ca2+] are also observed in the perinuclear region after 10-15 min treatment with Nod factors. The extracellular Ca2+ flux, detected with the non-invasive, calcium specific vibrating electrode, is inwardly directed and also increases quickly in response to Nod factors from 13 pmol cm-2 s-1 to 28 pmol cm-2 s-1. Chitin-oligomers, which are structurally similar but biologically inactive when compared to the active Nod factors, fail to elicit changes in either intracellular or extracellular Ca2+. The similar timing and location of the intracellular elevations and the increased extracellular influx provide support for the idea that Ca2+ participates in secretion and cell wall remodelling, which occur in anticipation of root hair deformation and curling.

Journal Article↗
PubMed1998

Accessory deep peroneal neuropathy: collision technique diagnosis.

Accessory deep peroneal nerve (ADPN), a common anatomic variant, is traditionally suspected when common peroneal nerve stimulation evokes a greater amplitude extensor digitorum brevis compound muscle action potential than deep peroneal nerve (DPN) stimulation. Posterolateral ankle stimulation over the ADPN is confirmatory. We report a rare patient with ADPN neuropathy in whom the collision technique was necessary to confirm the presence of an ADPN and to distinguish between neuropathy of the ADPN and the DPN.

Adult↗
PubMed1998

Sulfation of nod factors via nodHPQ is nodD independent in Rhizobium tropici CIAT899.

A cosmid from the Rhizobium tropici CIAT899 symbiotic plasmid, containing most of the nodulation genes described in this strain, has been isolated. Although this cosmid does not carry a nodD gene, it confers ability to heterologous Rhizobium spp. to nodulate R. tropici hosts (Phaseolus vulgaris, Macroptilium atropurpureum, and Leucaena leucocephala). The observed phenotype is due to constitutive expression of the nodABCSUIJ operon, which has lost its regulatory region and is expressed from a promoter present in the cloning vector. Thin-layer chromatography (TLC) analysis of the Nod factors produced by this construction shows that it is still capable of synthesizing sulfated compounds, suggesting that the nodHPQ genes are organized as an operon that is transcribed in a nodD-independent manner and is not regulated by flavonoids.

Bacterial Proteins↗
PubMed1998

Rearrangement of actin microfilaments in plant root hairs responding to rhizobium etli nodulation signals

The response of the actin cytoskeleton to nodulation (Nod) factors secreted by Rhizobium etli has been studied in living root hairs of bean (Phaseolus vulgaris) that were microinjected with fluorescein isothiocyanate-phalloidin. In untreated control cells or cells treated with the inactive chitin oligomer, the actin cytoskeleton was organized into long bundles that were oriented parallel to the long axis of the root hair and extended into the apical zone. Upon exposure to R. etli Nod factors, the filamentous actin became fragmented, as indicated by the appearance of prominent masses of diffuse fluorescence in the apical region of the root hair. These changes in the actin cytoskeleton were rapid, observed as soon as 5 to 10 min after application of the Nod factors. It was interesting that the filamentous actin partially recovered in the continued presence of the Nod factor: by 1 h, long bundles had reformed. However, these cells still contained a significant amount of diffuse fluorescence in the apical zone and in the nuclear area, presumably indicating the presence of short actin filaments. These results indicate that Nod factors alter the organization of actin microfilaments in root hair cells, and this could be a prelude for the formation of infection threads.

Journal Article↗
PubMed1997

Bacterial nodulation protein NodZ is a chitin oligosaccharide fucosyltransferase which can also recognize related substrates of animal origin.

The nodZ gene, which is present in various soil bacteria such as Bradyrhizobium japonicum, Azorhizobium caulinodans, and Rhizobium loti, is involved in the addition of a fucosyl residue to the reducing N-acetylglucosamine residue of lipochitin oligosaccharide (LCO) signal molecules. Using an Escherichia coli strain that produces large quantities of the NodZ protein of B. japonicum, we have purified the NodZ protein to homogeneity. The purified NodZ protein appears to be active in an in vitro transfucosylation assay in which GDP-beta-fucose and LCOs or chitin oligosaccharides are used as substrates. The products of the in vitro reaction using chitin oligosaccharides as substrate were studied by using mass spectrometry, linkage analysis, and composition analysis. The data show that one fucose residue is added to C6 of the reducing-terminal N-acetylglucosamine residue. The substrate specificity of NodZ protein was analyzed in further detail, using radiolabeled GDP-beta-fucose as the donor. The results show that chitin oligosaccharides are much better substrates than LCOs, suggesting that in Rhizobium NodZ fucosylates chitin oligosaccharides prior to their acylation. The free glycan core pentasaccharides of N-linked glycoproteins are also substrates for NodZ. Therefore, the NodZ enzyme seems to have an activity equivalent to that of the enzyme involved in the addition of the C6-linked fucosyl substituent in the glycan core of N-linked glycoproteins in eukaryotes. Oligosaccharides that contain only one N-acetylglucosamine at the reducing terminus are also substrates for NodZ, although in this case very high concentrations of such oligosaccharides are needed. An example is the leukocyte antigen Lewis-X, which can be converted by NodZ to a novel fucosylated derivative that could be used for binding studies with E-selectin.

Acetylglucosamine↗
PubMed1997

Median-ulnar anastomosis to thenar, hypothenar, and first dorsal interosseous muscles: collision technique confirmation.

Median-ulnar anastomosis (Martin-Gruber anastomosis; MGA) is traditionally diagnosed based upon changes in compound muscle action potential (CMAP) amplitude following proximal stimulation. We describe a rare patient with a MGA innervating thenar, hypothenar, and first dorsal interosseous muscles. Proximal stimulation, however, evoked CMAPs with striking changes in morphology and area but only minimal amplitude changes, due to concomitant diagnoses of carpal tunnel syndrome and polyneuropathy. Collision studies were therefore required for diagnostic confirmation of the MGA.

Action Potentials↗
PubMed1996

Thrombopoietic potential and serial repopulating ability of murine hematopoietic stem cells constitutively expressing interleukin 11.

Based on transplantation studies with bone marrow cultured under various conditions, a role of interleukin 11 (IL-11) in the self-renewal and/or the differentiation commitment of hematopoietic stem cells has been indicated. To better evaluate the in vivo effects of IL-11 on stem/progenitor cell biology, lethally irradiated mice were serially transplanted with bone marrow cells transduced with a defective retrovirus, termed MSCV-mIL-11, carrying the murine IL-11 (mIL-11) cDNA and the bacterial neomycin phosphotransferase (neo) gene. High serum levels (i.e., > 1 ng/ml) of mIL-11 in all (20/20) primary and 86% (12/14) of secondary long-term reconstituted mice, as well as 86% (12/14) of tertiary recipients examined at 6 weeks posttransplant, demonstrated persistence of vector expression subsequent to transduction of bone marrow precursors functionally definable as totipotent hematopoietic stem cells. In agreement with results obtained with human IL-11 in other myeloablation models, ectopic mIL-11 expression accelerated recovery of platelets, neutrophils, and, to some extent, total leukocytes while preferentially increasing peripheral platelet counts in fully reconstituted mice. When analyzed 5 months posttransplant, tertiary MSCV-mIL-11 recipients had a significantly greater percentage of G418-resistant colony-forming cells in their bone marrow compared with control MSCV animals. Collectively, these data show that persistent stimulation of platelet production by IL-11 is not detrimental to stem cell repopulating ability; rather, they suggest that IL-11 expression in vivo may have resulted in enhanced maintenance of the most primitive hematopoietic stem cell compartment. The prolonged expression achieved by the MSCV retroviral vector, despite the presence of a selectable marker, contrasts with the frequent transcriptional extinction observed with other retroviral vectors carrying two genes. These findings have potentially important implications for clinical bone marrow transplantation and gene therapy of the hematopoietic system.

Animals↗
PubMed1996

The role of the nodI and nodJ genes in the transport of Nod metabolites in Rhizobium etli.

A kinetic analysis of secretion of lipo-chitin oligosaccharides (LCO) produced by Rhizobium etli (Re) wild-type (wt) strain and derivatives carrying disrupted nodI or nodJ genes was performed. LCO were detected in the growth media of the wt strain as early as 1 h after nod gene induction. In contrast, strains carrying nodI or nodJ mutations secreted less LCO, and accumulated LCO metabolites intracellularly after 4 h of induction. These Re mutants presented a delayed nodulation phenotype and a reduction in the maximum number of nodules formed in Phaseolus vulgaris roots.

ATP-Binding Cassette Transporters↗