Biomedical subjects

Ferenc Nagy

Publications and source records attributed to Ferenc Nagy.

At least 37 records · Page 2Linked to original sources

PubMed2005

Nuclear accumulation of the phytochrome A photoreceptor requires FHY1.

The phytochrome family of red/far-red (R/FR)-responsive photoreceptors plays a key role throughout the life cycle of plants . Arabidopsis has five phytochromes, phyA-phyE, among which phyA and phyB play the most predominant functions . Light-regulated nuclear accumulation of the phytochromes is an important regulatory step of this pathway, but to this date no factor specifically required for this event has been identified . Among all phyA signaling mutants, fhy1 and fhy3 (far-red elongated hypocotyl 1 and 3) have the most severe hyposensitive phenotype, indicating that they play particularly important roles . FHY1 is a small plant-specific protein of unknown function localized both in the nucleus and the cytoplasm . Here we show that FHY1 is specifically required for the light-regulated nuclear accumulation of phyA but not phyB. Moreover, phyA accumulation is only slightly affected in fhy3, indicating that the diminished nuclear accumulation of phyA observed in fhy1 seedlings is not simply a general consequence of reduced phyA signaling. By in vitro pull-down and yeast two-hybrid analyses, we demonstrate that FHY1 physically interacts with phyA, preferentially in its active Pfr form. Furthermore, FHY1 and phyA colocalize in planta. We therefore identify the first component required for light-regulated phytochrome nuclear accumulation.

Arabidopsis↗

PubMed2005

MRI-assessed volume of left and right hippocampi in females correlates with the relative length of the second and fourth fingers (the 2D:4D ratio).

Atrophy of the left or right side of the hippocampus has been related to cognitive deficits and psychiatric disease. In this study, we examined the correlation between the hippocampal volume laterality index and the relative lengths of the second (index finger) and fourth (ring finger) digits (2D:4D) in healthy female subjects. The 2D:4D ratio is fixed in utero, and the ratio is higher in women than in men. There is evidence that this ratio is an indicator of the intrauterine concentration of testosterone, which influences the development of different regions of the brain. Assessing the volume of different parts of the brain of 40 healthy adult female students by magnetic resonance imaging (MRI), we found that the 2D:4D ratio was associated with an asymmetry in the hippocampal sub-regions. Smaller volume on the left side was found in the posterior part of the hippocampus in females with a low (masculine type) 2D:4D ratio. On the other hand, smaller volume on the left side was found in the middle part of the hippocampus in females with a high (female type) 2D:4D ratio. Thus, the development of the middle and posterior regions of the hippocampal formation may respond in opposite ways to prenatal levels of testosterone. Other brain regions such as the amygdala, the cerebral cortex, the total volume hippocampus, and the head of the hippocampus did not show such a difference.

Adult↗

PubMed2005

Functional characterization of phytochrome interacting factor 3 for the Arabidopsis thaliana circadian clockwork.

Light, in a quality- and quantity-dependent fashion, induces nuclear import of the plant photoreceptors phytochromes and promotes interaction of these receptors with transcription factors including PHYTOCHROME INTERACTING FACTOR 3 (PIF3). PIF3 was shown to form in vitro a ternary complex with the G-box element of the promoters of LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and the Pfr conformer of phytochromes. CCA1 and LHY together with TIMING OF CAB EXPRESSION 1 (TOC1) constitute a transcriptional feed-back loop that is essential for a functional circadian clock in Arabidopsis. These findings led to the hypothesis that the PIF3-containing ternary complex regulates transcription of light-responsive genes and is involved in phototransduction to the central circadian clockwork. Here we report that (i) overexpression or lack of biologically functional PIF3 does not affect period length of rhythmic gene expression or red-light-induced resetting of the circadian clock and (ii) the transcription of PIF3 displays a low-amplitude circadian rhythm. We demonstrated previously that irradiation of etiolated seedlings induces rapid, phytochrome-controlled degradation of PIF3. Here we show that nuclear-localized PIF3 accumulates to relatively high levels by the end of the light phase in seedlings grown under diurnal conditions. Taken together, we show that (i) PIF3 does not play a significant role in controlling light input to and function of the circadian clockwork and (ii) a yet unknown mechanism limits phytochrome-induced degradation of PIF3 at the end of the day under diurnal conditions.

Arabidopsis↗

PubMed2005

Plant circadian clocks increase photosynthesis, growth, survival, and competitive advantage.

Circadian clocks are believed to confer an advantage to plants, but the nature of that advantage has been unknown. We show that a substantial photosynthetic advantage is conferred by correct matching of the circadian clock period with that of the external light-dark cycle. In wild type and in long- and short-circadian period mutants of Arabidopsis thaliana, plants with a clock period matched to the environment contain more chlorophyll, fix more carbon, grow faster, and survive better than plants with circadian periods differing from their environment. This explains why plants gain advantage from circadian control.

Arabidopsis↗

PubMed2005

Clinical significance of granuloma in Crohn's disease.

AIM: Granuloma is considered the hallmark of microscopic diagnosis in Crohn's disease (CD), but granulomas can be detected in only 21-60% of CD patients. The aim of this study was to evaluate the frequency of granulomas by multiple endoscopic biopsies in patients with CD and to examine whether group of patients with or without granuloma exhibit a different clinical course. METHODS: Fifty-six patients with newly diagnosed CD were included in the study. Jejunoscopy, enteroclysis and ileo-colonoscopy were performed in all patients. At least two biopsy specimens from each examined gastrointestinal segment were examined microscopically searching granuloma. The clinical course was followed in all patients, and extraintestinal manifestations as well as details of any immunosuppressive therapy and surgical intervention were noted. RESULTS: Granuloma was found in 44.6% of the cases (25 patients). Patients with granuloma had higher activity parameters at the time of the biopsies. Extraintestinal manifestations were observed and surgical interventions were performed more often in the granuloma group. The need of immunosuppressive therapy was significantly more frequent in the patients with granuloma. Granuloma formation is more often seen in younger patients, and mainly in the severe, active penetrating disease. CONCLUSION: The significantly higher frequency of surgical interventions and immunosuppressive therapy suggests that granuloma formation is associated with a more severe disease course during the first years of CD.

Adolescent↗

PubMed2005

Natural allelic variation in the temperature-compensation mechanisms of the Arabidopsis thaliana circadian clock.

Temperature compensation is a defining feature of circadian oscillators, yet no components contributing to the phenomenon have been identified in plants. We tested 27 accessions of Arabidopsis thaliana for circadian leaf movement at a range of constant temperatures. The accessions showed varying patterns of temperature compensation, but no clear associations to the geographic origin of the accessions could be made. Quantitative trait loci (QTL) were mapped for period and amplitude of leaf movement in the Columbia by Landsberg erecta (CoL) and Cape Verde Islands by Landsberg erecta (CvL) recombinant inbred lines (RILs) at 12 degrees , 22 degrees , and 27 degrees . Six CvL and three CoL QTL were located for circadian period. All of the period QTL were temperature specific, suggesting that they may be involved in temperature compensation. The flowering-time gene GIGANTEA and F-box protein ZEITLUPE were identified as strong candidates for two of the QTL on the basis of mapping in near isogenic lines (NILs) and sequence comparison. The identity of these and other candidates suggests that temperature compensation is not wholly determined by the intrinsic properties of the central clock proteins in Arabidopsis, but rather by other genes that act in trans to alter the regulation of these core proteins.

Arabidopsis↗

PubMed2005

Analysis of the function of the photoreceptors phytochrome B and phytochrome D in Nicotiana plumbaginifolia and Arabidopsis thaliana.

To investigate the mechanism of phytochrome action in vivo, NtPHYB, AtPHYB and phyD:green fluorescent protein (GFP) were overexpressed in Nicotiana plumbaginifolia and Arabidopsis thaliana. The expression of 35S:NtPHYB:GFP and 35S:AtPHYB:GFP complemented the tobacco hgl2 and Arabidopsis phyB-9 mutations, whereas the 35S:AtPHYD:GFP only rescued the hgl2 mutant. All three fusion proteins are transported into the nucleus in all genetic backgrounds. These data indicate that AtPHYD:GFP is biologically active and functions as the main red light receptor in transgenic tobacco, and establish an experimental system for the functional analysis of this elusive photoreceptor in vivo.

Active Transport, Cell Nucleus↗

PubMed2005

Phytochrome-specific type 5 phosphatase controls light signal flux by enhancing phytochrome stability and affinity for a signal transducer.

Environmental light information such as quality, intensity, and duration in red (approximately 660 nm) and far-red (approximately 730 nm) wavelengths is perceived by phytochrome photoreceptors in plants, critically influencing almost all developmental strategies from germination to flowering. Phytochromes interconvert between red light-absorbing Pr and biologically functional far-red light-absorbing Pfr forms. To ensure optimal photoresponses in plants, the flux of light signal from Pfr-phytochromes should be tightly controlled. Phytochromes are phosphorylated at specific serine residues. We found that a type 5 protein phosphatase (PAPP5) specifically dephosphorylates biologically active Pfr-phytochromes and enhances phytochrome-mediated photoresponses. Depending on the specific serine residues dephosphorylated by PAPP5, phytochrome stability and affinity for a downstream signal transducer, NDPK2, were enhanced. Thus, phytochrome photoreceptors have developed an elaborate biochemical tuning mechanism for modulating the flux of light signal, employing variable phosphorylation states controlled by phosphorylation and PAPP5-mediated dephosphorylation as a mean to control phytochrome stability and affinity for downstream transducers.

Arabidopsis↗

PubMed2005

NOD2/CARD15 gene polymorphism in patients with inflammatory bowel disease: is Hungary different?

AIM: To analyse the impact of NOD2/CARD15 mutations on the clinical course of Crohn's disease patients from an eastern European country (Hungary). METHODS: We investigated the prevalence of the three common NOD2/CARD15 mutations (Arg702Trp, Gly908Arg, 1007finsC) in 148 patients with Crohn's disease, 128 patients with ulcerative colitis and 208 controls recruited from the University of Szeged, Hungary. In patients with Crohn's disease, the prevalence of NOD2/CARD15 mutations was correlated to the demographical and clinical parameters. RESULTS: In total, 32.4% of Crohn's disease patients carried at least one mutant allele within NOD2/CARD15 compared to 13.2% of patients with ulcerative colitis (P = 0.0002) and to 11.5% of controls (P<0.0001). In Crohn's disease patients, the allele frequencies for Arg702Trp, Gly908Arg and 1007finsC were 7.1%, 3.0% and 10.8% respectively. Interestingly, only the 1007finsC mutation was associated with a distinct clinical phenotype. The patients positive for the 1007finsC mutation suffered more frequently from stenotic disease behaviour (P = 0.008). Furthermore, 51.9% of patients positive for the 1007finsC mutation underwent a surgical resection within the ileum compared to only 17.4% of patients without the 1007finsC mutation (P = 0.001). With respect to the other two mutations (Arg702Trp and Gly908Arg), no associations were found with all investigated clinical parameters. CONCLUSION: NOD2/CARD15 mutations are frequently found in Crohn's disease patients from Hungary. The 1007finsC mutation is associated with stenotic disease behaviour and frequent ileal resections.

Adolescent↗

PubMed2005

Signalling and gene regulation in response to ultraviolet light.

In contrast to phytochrome-, cryptochrome- and phototropin-sensing systems, about which considerable knowledge has accumulated, the ultraviolet-B (UVB) photoreceptor is not yet known at the molecular level. Information about the downstream signalling events that underlie UVB-provoked physiological responses is limited. Recent whole-genome transcript profiling, isolation of mutants that are impaired in specific UVB-induced responses and detailed photobiological studies suggest that responses that are triggered by shorter wavelength UVB and longer wavelength UVB are mediated by two different sensory systems. The bZIP transcription factor HY5 was recently identified as an important player in the long-wavelength UVB-induced signal transduction cascade. Advances in the development of luciferase-reporter lines will make it feasible to perform high-throughput genetic screens to isolate novel mutants that are impaired in sensing or transducing signals downstream of the putative UVB photoreceptor(s).

Gene Expression Regulation, Plant↗

PubMed2005

Polymorphism of the heat-shock protein gene Hsp70-2, but not polymorphisms of the IL-10 and CD14 genes, is associated with the outcome of Crohn's disease.

OBJECTIVE: In Crohn's disease (CD) a Th-1 dominant immune reaction is induced, which could be associated with genetic predisposition. Several previous studies have investigated the roles of CD14, heat-shock protein (Hsp)70 and IL-10 gene polymorphisms in the development of the disease. The results are contradictory and inter-racial differences are implicated. Therefore, this phenomenon was evaluated in well-documented Caucasian patients with CD in order to verify the clinical importance of these polymorphisms. MATERIAL AND METHODS: The genomic DNA of 133 patients with CD and that of 75 healthy controls were examined. CD was divided into subgroups according to the Vienna classification. An arbitrary classification system based on disease severity was also applied, which was determined according to the therapeutic intervention. The CD14 (-159 C-->T) promoter gene polymorphism was investigated by melting-point analysis. The IL-10 (-1082 G-->A) and Hsp70-2 (1267 A-->G) gene polymorphisms were detected by RFLP (restriction fragment length polymorphism). RESULTS: None of the allele frequencies of the examined polymorphisms differed significantly between the patient and control populations. Neither the CD14 nor the IL-10 polymorphisms exhibited any correlation with the development or with the progression of the disease. With regard to Hsp70-2 gene polymorphism, those patients who carry at least one A allele have a significantly lower probability of the need for surgical intervention. CONCLUSIONS: Allele A of the Hsp70-2 gene may be associated with a less severe form of CD, suggesting the clinical value of the genotype assessment. The genetic determination of the defense mechanisms in CD appears to be associated with the polymorphism of the Hsp70-2 gene rather than that of the CD14 or IL-10 genes.

Adult↗

PubMed2004

[Ulcerative colitis and eosinophilic corpus gastritis].

Ulcerative colitis seldom associated with nutritive and/or salicylate allergy. Authors present a case of both allergic events at the course of the disease. In 1996 a 19-year-old girl was referred with a history of blood in stool as well as diarrhoea, suggesting ulcerative proctitis. Biopsy revealed ulcerative colitis of the rectum mucosa with eosinophilic infiltration and 20% peripheral eosinophilia was found. Allergic origin and worm infection were ruled out, and after tinidazol treatment, four year elapsed without any signs or symptoms. In December 2000 blood in stools and upper abdominal complaints developed without peripheral eosinophilia. Gastroscopy and biopsy showed a mild chronic gastritis. Olsalazine, budesonide enema and famotidin treatment were started, but then later changed to mesalazine and pantoprazol, because of the constant stomach complaints. The next five months passed without any symptoms. The patient had to break off her seashore journey in July 2000 because of stomach complaints, vomiting and exsiccosis. Peripheral eosinophilia (27.3%) was evident. Gastroscopy revealed erosive ulcers and the biopsy showed eosinophilic gastritis. Biopsies from the jejunum, duodenum and antrum as well as enteroscopy and biopsies from the rectum showed mild eosinophilic infiltration. An allergy test proved the presence of IgE against salicylate, egg protein, seafood protein and the lymphocyte transformation test was also positive against salicylate. Oral food challenges proved to be negative and the amino-salicylate treatment was stopped. After a temporary symptom free period, bloody stools reappeared in May 2003; the peripheral eosinophilia still existed, but had decreased (22.2%). Esomeprazol, and methyl-prednisolone containing enema (40 mg/day/2 weeks) followed by budesonide enema twice a week resulted in a symptom free period and peripheral eosinophilia became almost normalised (6.2%). The authors report a case having ulcerative proctitis first, than nutritive and salicylate allergy with eosinophilic gastritis and a proctitis flare-up thereafter.

Adult↗

PubMed2004

Phytochrome phosphorylation modulates light signaling by influencing the protein-protein interaction.

Plant photoreceptor phytochromes are phosphoproteins, but the question as to the functional role of phytochrome phosphorylation has remained to be elucidated. We investigated the functional role of phytochrome phosphorylation in plant light signaling using a Pfr-specific phosphorylation site mutant, Ser598Ala of oat (Avena sativa) phytochrome A (phyA). The transgenic Arabidopsis thaliana (phyA-201 background) plants with this mutant phyA showed hypersensitivity to light, suggesting that phytochrome phosphorylation at Serine-598 (Ser598) in the hinge region is involved in an inhibitory mechanism. The phosphorylation at Ser598 prevented its interaction with putative signal transducers, Nucleoside Diphosphate Kinase-2 and Phytochrome-Interacting Factor-3. These results suggest that phosphorylation in the hinge region of phytochromes serves as a signal-modulating site through the protein-protein interaction between phytochrome and its putative signal transducer proteins.

Avena↗

PubMed2004

Constitutive photomorphogenesis 1 and multiple photoreceptors control degradation of phytochrome interacting factor 3, a transcription factor required for light signaling in Arabidopsis.

Light, in a quality- and quantity-dependent fashion, induces nuclear import of the plant photoreceptors phytochrome, promotes interaction of phytochrome A (phyA) and phyB with transcription factors including phytochrome interacting factor 3 (PIF3), and is thought to trigger a transcriptional cascade to regulate the expression of approximately 2500 genes in Arabidopsis thaliana. Here, we show that controlled degradation of the transcription factor PIF3 is a major regulatory step in light signaling. We demonstrate that accumulation of PIF3 in the nucleus in dark requires constitutive photomorphogenesis 1 (COP1), a negative regulator of photomorphogenesis, and show that red (R) and far-red light (FR) induce rapid degradation of the PIF3 protein. This process is controlled by the concerted action of the R/FR absorbing phyA, phyB, and phyD photoreceptors, and it is not affected by COP1. Rapid light-induced degradation of PIF3 indicates that interaction of PIF3 with these phytochrome species is transient. In addition, we provide evidence that the poc1 mutant, a postulated PIF3 overexpressor that displays hypersensitivity to R but not to FR, lacks detectable amounts of the PIF3 protein. Thus, we propose that PIF3 acts transiently, and its major function is to mediate phytochrome-induced signaling during the developmental switch from skotomorphogenesis to photomorphogenesis and/or dark to light transitions.

Arabidopsis↗

PubMed2004

Phytohormones participate in an S6 kinase signal transduction pathway in Arabidopsis.

Addition of fresh medium to stationary cells of Arabidopsis suspension culture induces increased phosphorylation of the S6 ribosomal protein and activation of its cognate kinase, AtS6k. Analysis of the activation response revealed that medium constituents required for S6 kinase activation were the phytohormones 1-naphthylacetic acid (auxin) and kinetin. Pretreatment of cells with anti-auxin or PI3-kinase drugs inhibited this response. Consistent with these findings, LY294002, a PI3-kinase inhibitor, efficiently suppressed phytohormone-induced S6 phosphorylation and translational up-regulation of ribosomal protein S6 and S18A mRNAs without affecting global translation. These data indicate that (1) activation of AtS6k is regulated by phytohormones, at least in part, via a lipid kinase-dependent pathway, that (2) the translational regulation of ribosomal proteins appears to be conserved throughout the plant and animal kingdom, and that (3) these events are hallmarks of a growth-related signal transduction pathway novel in plants.

Arabidopsis↗

PubMed2004

Genome-wide analysis of gene expression reveals function of the bZIP transcription factor HY5 in the UV-B response of Arabidopsis.

The light environment is a key factor that governs a multitude of developmental processes during the entire life cycle of plants. An important and increasing part of the incident sunlight encompasses a segment of the UV-B region (280-320 nm) that is not entirely absorbed by the ozone layer in the stratosphere of the earth. This portion of the solar radiation, which inevitably reaches the sessile plants, can act both as an environmental stress factor and an informational signal. To identify Arabidopsis genes involved in the UV response, we monitored the gene expression profile of UV-B-irradiated seedlings by using high-density oligonucleotide microarrays comprising almost the full Arabidopsis genome (>24,000 genes). A robust set of early low-level UV-B-responsive genes, 100 activated and 7 repressed, was identified. In all cases analyzed, UV-B induction was found to be independent of known photoreceptors. This group of genes is suggested to represent the molecular readout of the signaling cascade triggered by the elusive UV-B photoreceptor(s). Moreover, our analysis identified interactions between cellular responses to different UV-B ranges that led us to postulate the presence of partially distinct but interacting UV-B perception and signaling mechanisms. Finally, we demonstrate that the bZIP transcription factor HY5 is required for UV-B-mediated regulation of a subset of genes.

Arabidopsis↗

PubMed2004

[Multiple organ resections for the surgical treatment of locally advanced colorectal cancer infiltrating the urinary tract].

The authors present data on 13 patients operated on for the treatment of locally advanced colorectal cancer infiltrating the adjacent parts of the urinary tract. Based on prior diagnostic evidences, every surgical intervention has been indicated as an expected curative resection. All patients of this study underwent a curative resection. The origin of the advanced cancer was in 9 cases the sigmoid colon, in 3 cases the rectum and in 1 case the ascending colon. Beside the resection of the tumorous colon or rectum, a resection of the urinary bladder has been performed in 9, a nephrectomy in 3 and the resection of the ureter in 2 cases. An additional gynecological resection was made in 4 cases for tumors infiltrating the female internal genitals. No mortality and no serious complication needing reoperation occurred in these series. Based on their experiences of a series of 13 radically operated cases, the authors suggest extended multiple organ resection for the treatment of advanced colorectal cancer infiltrating the urinary tract.

Adnexa Uteri↗

PubMed2004

[Causes of local recurrence after curative surgery for rectal cancer].

The rate of local recurrence (LR) has been 20-40% after resective surgery for rectal cancer by the traditional - Miles or Dixon - operative technics. The authors performed curative resection in 358 patients with rectal cancer in a 10 year period (01.01.1990 - 31.12.2000) in the Surgical Department of Szeged University. Since 01.01.1996 the authors changed this type of surgery for the Heald technics (total mesorectal excision - TME - with sharp dissection, using the UltraCision device) for the surgical treatment of middle or lower third rectal cancer. To compare the results of the two procedures, the authors analysed their material in two periods: Period I: 01.01.1991 - 31.12.1992: 62 patients operated on with the traditional operative technics; LR 15% within 2 years after surgery. Period II: 01.01.1997 - 31.12.1998: 78 patients operated on with the Heald technics (TME with sharp dissection); LR 6.4% within 2 years after surgery. Based on their results, the authors found that the modern operative technics by Heald, used in the second period of the study, was a relevant factor decreasing LR from 15% to 6.4%, while the gender, age of the patients, ratio of the abdominoperineal extirpation versus anterior resection (APRE/AR) and the free margin of more than 3 cm proved to be irrelevant.

Age Factors↗