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PubMedDate not supplied

Small hepatic nodules in cirrhosis: ultrasonographic, CT, and MR imaging findings.

PURPOSE: The purpose of this study was to assess the imaging findings of pathologically-proved small hepatic nodules 2 cm in size or smaller detected with ultrasonography in cirrhotic patients with suspected hepatocellular carcinoma (HCC). MATERIALS AND METHODS: We evaluated sonographically detected 32 small hepatic nodules which were pathologically confirmed in 23 consecutive cirrhotic patients who were suspected of having HCC. Twenty-six lesions were confirmed with ultrasonographically-guided aspiration needle-core biopsy, and six with definitive surgery. Ultrasonographic examination records were retrospectively reviewed. CT, and MR images obtained with various imaging techniques were retrospectively reviewed by two radiologists in a blind fashion. RESULTS: The 32 hepatic nodules were comprised of seven focal fatty changes, two large regenerative nodules, three low-grade dysplastic nodules, five high-grade dysplastic nodules, and fifteen HCCs. Ultrasonography showed various echogenicity for the hepatic nodules. The signal-intensity characteristics with T1-weighted spin-echo, in-phase gradient-recalled-echo, and dynamic MR imagings may be useful in distinguishing HCC from nonHCC nodules. CONCLUSIONS: Nearly half of small hepatic nodules detected with ultrasonography were nonHCC nodules. Ultrasonographic findings may not be reliable in characterizing small hepatic nodules in cirrhosis. CT and MR imaging obtained with the various techniques are still insensitive to these hepatic nodules.

Aged↗

PubMed2003

The probability of malignancy in small pulmonary nodules coexisting with potentially operable lung cancer detected by CT.

The aim of this study was to assess the probability of malignancy in one or two small nodules 1 cm or less coexisting with potentially operable lung cancer (coexisting small nodules). The preoperative helical CT scans of 223 patients with lung cancer were retrospectively reviewed. The probability of malignancy of coexisting small nodules was evaluated based on nodule size, location, and clinical stage of the primary lung cancers. Seventy-one coexisting small nodules were found on conventional CT in 58 (26%) of 223 patients, and 14 (6%) patients had malignant nodules. Eighteen (25%) of such nodules were malignant. The probability of malignancy was not significantly different between two groups of nodules larger and smaller than 0.5 cm ( p=0.1). The probability of malignancy of such nodules within primary tumor lobe was significantly higher than that in the other lobes ( p<0.01). Metastatic nodules were significantly fewer in clinical stage-IA patients than in the patients with the other stage ( p<0.01); however, four (57%) of seven synchronous lung cancers were located in the non-primary tumor lobes in the clinical stage-I patients. Malignant coexisting small nodules are not infrequent, and such nodules in the non-primary tumor lobes should be carefully diagnosed.

Adult↗

PubMed1998

The pea (Pisum sativum L.) genes sym33 and sym40 control infection thread formation and root nodule function.

Two novel non-allelic mutants that were unable to fix nitrogen (Fix ) were obtained after EMS (ethyl methyl sulfonate) mutagenesis of pea (Pisum sativum L.). Both mutants, SGEFix(-)-1) and SGEFix(-)-2, form two types of nodules: SGEFix(-)-1 forms numerous white and some pink nodules, while mutant SGEFix(-)-2 forms white nodules with a dark pit at the distal end and also some pinkish nodules. Both mutations are monogenic and recessive. In both lines the manifestation of the mutant phenotype is associated with the root genotype. White nodules of SGEFix(-)-1 are characterised by hypertrophied infection threads and infection droplets, mass endocytosis of bacteria, abnormal morphological differentiation of bacteroids, and premature degradation of nodule symbiotic structures. The structure of the pink nodules of SGEFix(-)-1 does not differ from that of the parental line, SGE. White nodules of SGEFix(-)-2 are characterised by "locked" infection threads surrounded with abnormally thick plant cell walls. In these nodules there is no endocytosis of bacteria into host-cell cytoplasm. The pinkish nodules of SGEFix(-)-2 are characterised by virtually undifferentiated bacteroids and premature degradation of nodule tissues. Thus, the novel pea symbiotic genes, synm40 and sym33, identified after complementation analysis in SGEFix(-)-1 and SGEFix(-)-2 lines, respectively, control early nodule developmental stages connected with infection thread formation and function.

Cell Wall↗

PubMed2006

Effect of salinity on root-nodule conductance to the oxygen diffusion in the Cicer arietinum-Mesorhizobium ciceri symbiosis.

Nodule conductance to O2 diffusion has been involved as a major factor of the inhibition of N2 fixation by soil salinity that severely reduces the production of grain legumes. In order to determine the effect of this constraint on the nodule conductance, oxygen uptake by the nodulated roots of Cicer arietinum was measured by recording the concentration of O2 as a function of pO2 in a gas-tight incubator. After germination and inoculation with the strain Mesorhizobium ciceri UPMCa7, the varieties Amdoun 1 and INRAT 93-1 were hydroponically grown in a glasshouse on 1L glass bottles filled with nutrient solution containing 25 mM NaCl. Salinity induced a marked decrease in shoot (30% versus 14%), root (43% versus 20%), and nodule biomass (100% versus 43%) for Amdoun 1 relative to INRAT 93-1. Although salinity completely prevented nodule formation in the sensitive variety Amdoun 1, nodule number and biomass were higher in the first than in the second variety in the absence of salt. This effect was associated with a significantly higher O2 uptake by nodulated root (510 versus 255 micromol O2 plant(-1)h(-1)) and nodule conductance (20 versus 5 microm s(-1)) in Amdoun 1 than in INRAT 93-1. Salinity did not significantly change the nodule conductance and nodule permeability for INRAT 93-1. Thus, the salt tolerance of this variety appears to be associated with stability in nodule conductance and the capacity to form nodules under salt constraint.

Biomass↗

PubMed2003

Adipokinetic hormone enhances nodule formation and phenoloxidase activation in adult locusts injected with bacterial lipopolysaccharide.

Interactions between the locust endocrine and immune systems have been studied in vivo in relation to nodule formation and activation of the prophenoloxidase cascade in the haemolymph. Injection of bacterial lipopolysaccharide (LPS) extracted from Escherichia coli induces nodule formation in larval and adult locusts but does not increase phenoloxidase activity in the haemolymph. Nodule formation starts rapidly after injection of LPS and is virtually complete within 8 h, nodules occurring mainly associated with the dorsal diaphragm on either side of the heart, but sometimes with smaller numbers associated with the ventral diaphragm on either side of the nerve cord. Co-injection of adipokinetic hormone-I (Lom-AKH-I) with LPS stimulates greater numbers of nodules to be formed in larval and adult locusts, and activates phenoloxidase in the haemolymph of mature adults but not of nymphs. The effect of co-injection of Lom-AKH-I with LPS on nodule formation is seen at low doses of hormone; only 0.4 pmol of Lom-AKH-I per adult locust is needed to produce a 50% increase in the number of nodules formed. When different components of LPS from the E. coli Rd mutant are tested, the mono- and the diphosphoryl Lipid A components have similar effects to the intact LPS. Remarkably, detoxified LPS activates phenoloxidase in the absence of Lom-AKH-I, although co-injection with hormone does enhance this response. Both diphosphoryl Lipid A and detoxified LPS induce a level of nodule formation that is enhanced by co-injection of Lom-AKH-I, but monophosphoryl Lipid A does not initiate nodule formation even when injected with hormone. Co-injection of a water-soluble inhibitor of eicosanoid synthesis, diclofenac (2-[(2, 6-dichlorophenyl)amino] benzeneacetic acid), reduces nodule formation in response to injections of LPS (both in the absence and presence of hormone) in a dose-dependent manner, but does not prevent activation of phenoloxidase in adult locusts. It is shown that nodule formation and activation of the prophenoloxidase in locust haemolymph can both be enhanced by Lom-AKH-I, but it is argued that these processes involve distinct mechanisms in which eicosanoid synthesis is important for nodule formation, but not for the increased phenoloxidase activity.

Animals↗

PubMed1999

Placental site nodule and characterization of distinctive types of intermediate trophoblast.

Both placental site nodule and exaggerated placental site are described as being composed of intermediate trophoblast (IT), yet their morphological features and clinical presentation differ significantly. This study was undertaken to evaluate the morphological and immunohistochemical features of trophoblastic cells in placental site nodules and compare them with the trophoblastic cells in exaggerated placental sites as well as in different anatomic locations in the developing placenta to evaluate these differences. Forty-two placental site nodules, 20 abortus specimens ranging from 3 to 13 weeks, 8 second- and 10 third-trimester placentas, and 12 exaggerated placental sites were studied by conventional light microscopy and immunohistochemistry. This analysis showed that the trophoblastic cells in the placental site nodule closely resemble those in the chorion laeve. We have designated these cells "chorionic-type IT cells." They are composed of two populations of cells, one with eosinophilic and the other with clear (glycogen-rich) cytoplasm. The eosinophilic cells tended to be larger with more pleomorphic nuclei, whereas the clear cells were smaller with more uniform nuclei. Chorionic-type IT cells in the chorion laeve and placental site nodule were diffusely positive for placental alkaline phosphatase but were only focally positive or negative for human placental lactogen (hPL), Mel-CAM (CD146), and oncofetal fibronectin. In contrast, hPL, Mel-CAM, and oncofetal fibronectin were diffusely expressed in IT cells in the placental site, both normal and exaggerated. The chorionic-type IT cells in placental site nodule and chorion laeve showed mild proliferative activity as indicated by an increased Ki-67 labeling index (3% to 10%). In contrast, the Ki-67 labeling index in normal and exaggerated implantation sites was zero. The morphological and immunohistochemical features of chorionic-type IT cells contrast with the IT cells in the implantation site that we have designated "implantation site IT cells." Both types of IT cells develop from a population of trophoblastic cells in the trophoblastic columns that we have tentatively termed "villous IT cells." Four of 42 placental site nodules were larger (>5 mm) than the remainder and showed transitional features between a typical placental site nodule and an epithelioid trophoblastic tumor, a recently described distinctive gestational trophoblastic tumor. There were no recurrences among the placental site nodules regardless of size. All placental site nodules were immunoreactive for inhibin-alpha and cytokeratin 18, whereas 33 squamous cell carcinomas of the cervix, which can at times be confused with placental site nodules, were negative. In conclusion, there appear to be three subpopulations of IT cells with distinctive morphological and immunohistochemical features. Different subpopulations can be related to different trophoblastic lesions: implantation site IT cells to an exaggerated placental site and its neoplastic counterpart, placental site trophoblastic tumor and chorionic-type IT cells to a placental site nodule and its neoplastic counterpart, epithelioid trophoblastic tumor.

Adult↗

PubMed2000

Seed storage protein composition of non-nodulating soybean (Glycine max (L.) Merr.) and its influence on protein quality.

A 53 kDa protein, which accumulates at low levels in non-nodulating Clark soybeans, was purified by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Polyclonal antibodies were raised against the gel-purified protein. N-terminal sequence analysis identified the 53 kDa protein as the beta-subunit of beta-conglycinin. Results from Western blot analysis, using antibodies raised against the purified beta-subunit of beta-conglycinin, revealed that accumulation of this protein was enhanced in non-nodulating soybeans when the plants were supplemented with nitrogen. Results from Northern blot analysis indicate that non-nodulating soybeans in general had lower levels of mRNA for the major soybean seed proteins. A one-time application of nitrogen to non-nodulating soybeans enhanced the accumulation of the 1.6 kb beta-conglycinin beta-subunit mRNA. The mRNA levels of the 2.1 kb beta-conglycinin alpha'-subunit and the 2.2 kb G4 glycinin in the non-nodulating soybeans were several-fold lower than in nodulating soybeans. Nitrogen application had no effect on the abundance of these RNA transcripts. The amount of RNA encoding an 8.5 kDa sulfur-rich protein was two-fold higher in non-nodulating soybeans when compared with nodulated soybeans. Nitrogen application reduced the abundance of this transcript to levels comparable with those of nodulated soybeans. Despite lower levels of the beta-subunit of beta-conglycinin, the methionine content of the total seed protein fraction was lower than that of nodulated soybeans. In contrast, non-nodulating soybeans contained more cysteine than nodulating soybeans.

Journal Article↗

PubMed1998

Prognostic implications of pulmonary satellite nodules: are the 1997 staging revisions appropriate?

In the 1992 AJCC and 1993 UICC staging systems, primary lobe satellite nodules increased the T designation of the primary by one level and ipsilateral non-primary lobe satellite nodules raised the T designation to T4. The recent 1997 UICC and AJCC staging revisions assign a T4 (IIIb) designation to satellite nodules in a primary lobe, and a M1 (IV) designation to satellites in ipsilateral non-primary lobes. There is abundant evidence showing that satellite nodules are negative prognostic factors, but their inclusion in stage IIIb and IV may not be appropriate. The English-language medical literature was searched for papers reporting survival after surgical resection of lung cancer with satellite nodules (primary and non-primary ipsilateral lobe locations). Eleven articles were retrieved and their data pooled for analysis. Of 568 resected patients with satellite nodules, actuarial 5-year survival was 20%. Five articles gave separate survival data for satellite nodules in primary versus ipsilateral non-primary lobes. All five articles showed better survival for satellite nodules in a primary lobe. Satellite nodules in a primary lobe have a better prognosis than those in ipsilateral non-primary lobes. Survival for resected lung cancer with satellite nodules in a primary lobe is better than that usually observed for T4 (IIIB) disease. The 1997 staging revisions may unduly upstage patients with satellite nodules in a primary cancer lobe. However, satellite nodules in ipsilateral non-primary lobes share metastatic mechanisms and have survival results consistent with M1 stage disease. Their 1997 MI designation may be appropriate.

Humans↗

PubMed1988

Rhizobium fix genes mediate at least two communication steps in symbiotic nodule development.

To identify bacterial genes involved in symbiotic nodule development, ineffective nodules of alfalfa (Medicago sativa) induced by 64 different Fix-mutants of Rhizobium meliloti were characterized by assaying for symbiotic gene expression and by morphological studies. The expression of leghemoglobin and nodulin-25 genes from alfalfa and of the nifHD genes from R. meliloti were monitored by hybridizing the appropriate DNA probes to RNA samples prepared from nodules. The mutants were accordingly divided into three groups. In group I none of the genes were expressed, in group II only the plant genes were expressed and in group III all three genes were transcribed. Light and electron microscopical analysis of nodules revealed that nodule development was halted at different stages in nodules induced by different group I mutants. In most cases nodules were empty lacking infection threads and bacteroids or nodules contained infection threads and a few released bacteroids. In nodules induced by a third mutant class bacteria were released into the host cells, however the formation of the peribacteroid membrane was not normal. On this basis we suggest that peribacteroid membrane formation precedes leghemoglobin and nodulin-25 induction, moreover, after induction of nodulation by the nod genes at least two communication steps between the bacteria and the host plants are necessary for the development of the mature nodule. By complementing each mutant of group I with a genomic R. meliloti library made in pLAFRl, four new fix loci were identified, indicating that several bacterial genes are involved in late nodule development.

Gene Expression Regulation↗

PubMed2002

Effect of exogenous flavonoids on nodulation of pea (Pisum sativum L.).

Selected flavonoids that are known as inducers and a suppressor of nodulation (nod) genes of the symbiotic bacterium Rhizobium leguminosarum bv. viciae were tested for their effect on symbiosis formation with garden pea as the host. A solid substrate was omitted from the hydroponic growing system in order to prevent losses of flavonoids due to adsorption and degradation. The presumed interaction of the tested flavonoids with nod genes has been verified for the genetic background of strain 128C30. A stimulatory effect of a nod gene inducer naringenin on symbiotic nodule number formed per plant 14 d after inoculation was detected at concentrations of 0.1 and 1 micro g ml(-1) nutrient solution. At 10 micro g ml(-1), the highest concentration tested, naringenin was already inhibitory. By contrast, nodulation was negatively affected by a nod gene suppressor, quercetin, at concentrations above 1 micro g ml(-1), as well as by another tested nod gene inducer, hesperetin. The deleterious effect of hesperetin might be due to its toxicity or to the toxicity of its degradation product(s) as indicated by the inhibition of root growth. Both the stimulatory effect of naringenin and the inhibitory effect of quercetin on nodule number were more pronounced at earlier stages of nodule development as revealed with specific staining of initial nodules. The lessening of the flavonoid impact during nodule development was ascribed to the plant autoregulatory mechanisms. Feedback regulation of nodule metabolism might also be responsible for the fact that the naringenin-conditioned increase in nodule number was not accompanied by any increase in nitrogenase activity. By contrast, the inhibitory action of quercetin and hesperetin on nodule number was associated with decreases in total nitrogenase activity. Naringenin also stimulated root hair curling (RHC) as one of the earliest nodulation responses at concentrations of 1 and 10 microg ml(-1), however, the same effect was exerted by the nod gene suppressor, quercetin, suggesting that feedback regulatory mechanisms control RHC in the range of nodulation-inhibiting high flavonoid concentrations. The comparison of the effect of the tested flavonoids in planta with nod gene activity response showed a two orders of magnitude shift to higher concentrations. This shift is explained by the absorption and degradation of flavonoids by both the symbionts during 3 d intervals between hydroponic solution changes. The losses were 99, 96.4, and 90% of the initial concentration of 10 micro g ml(-1) for naringenin, hesperetin, and quercetin, respectively.

Flavanones↗

PubMed2005

Grafting between model legumes demonstrates roles for roots and shoots in determining nodule type and host/rhizobia specificity.

Previous grafting experiments have demonstrated that legume shoots play a critical role in symbiotic development of nitrogen-fixing root nodules by regulating nodule number. Here, reciprocal grafting experiments between the model legumes Lotus japonicus and Medicago truncatula were carried out to investigate the role of the shoot in the host-specificity of legume-rhizobia symbiosis and nodule type. Lotus japonicus is nodulated by Mesorhizobium loti and makes determinate nodules, whereas M. truncatula is nodulated by Sinorhizobium meliloti and makes indeterminate nodules. When inoculated with M. loti, L. japonicus roots grafted on M. truncatula shoots produced determinate nodules identical in appearance to those produced on L. japonicus self-grafted roots. Moreover, the hypernodulation phenotype of L. japonicus har1-1 roots grafted on wild-type M. truncatula shoots was restored to wild type when nodulated with M. loti. Thus, L. japonicus shoots appeared to be interchangeable with M. truncatula shoots in the L. japonicus root/M. loti symbiosis. However, M. truncatula roots grafted on L. japonicus shoots failed to induce nodules after inoculation with S. meliloti or a mixture of S. meliloti and M. loti. Instead, only early responses to S. meliloti such as root hair tip swelling and deformation, plus induction of the early nodulation reporter gene MtENOD11:GUS were observed. The results indicate that the L. japonicus shoot does not support normal symbiosis between the M. truncatula root and its microsymbiont S. meliloti, suggesting that an unidentified shoot-derived factor may be required for symbiotic progression in indeterminate nodules.

Fabaceae↗

PubMed1996

Evaluation of blood flow signal in small hepatic nodules by color Doppler ultrasonography.

Small hepatic nodular lesions are frequently detected by ultrasonography in patients with liver cirrhosis during follow-up. However, hepatocellular carcinomas (HCCs) and non-HCC nodules are difficult to differentiate by ultrasonography because they have a similar appearance. We used color Doppler ultrasonography (CDU) to examine 29 HCCs and 26 non-HCC nodules less than 2 cm in diameter to determine whether CDU can be used to differentiate small hepatic nodules. There were no significant differences between the examined HCCs and non-HCC nodules with regard to ultrasonographic appearance, i.e., hypoechoicity or hyperechoicity. Blood flow signals were detected in a significantly higher percentage of HCCs (13 of 29, 44.8%) than in non-HCC nodules (2 of 26, 7.7%; P<0.005), although the sensitivity was low. Therefore, we classified nodules as hypoechoic or hyperechoic by B-mode ultrasonography and examined their blood flow signals. Among nodules that were hypoechoic, signals were detected in a significantly higher percentage of HCCs (12 of 18, 66.7%) than in non-HCC nodules (2 of 13, 15.4%; P<0.005). In contrast, among hyperechoic nodules, signals were detected in only 1 of 11 (9.1%) HCCs and in 0 of 13 non-HCC nodules. Our results suggest that examination of blood flow by CDU is useful for differentiating small hepatic nodules, especially hypoechoic nodules.

Blood Flow Velocity↗

PubMed2002

Autoregulation of root nodule formation: signals of both symbiotic partners studied in a split-root system of Vicia sativa subsp. nigra.

Inhibition of root nodule formation on leguminous plants by already induced or existing root nodules is called autoregulation of root nodule formation (AUT). Optimal conditions for AUT were determined using a split-root technique newly developed for Vicia sativa subsp. nigra. Infection of a root A with nodulating Rhizobium leguminosarum bv. viciae bacteria systemically inhibited nodulation of a spatially separated root B inoculated 2 days later with the same bacteria. This treatment gives complete AUT (total absence of nodules on root B). Only partial AUT of root B was obtained by incubation of root A with mitogenic nodulation (Nod) factors or with a noninfective strain producing normal mitogenic Nod factors. Nonmitogenic Nod factors did not evoke AUT. We identified two systemic plant signals induced by Rhizobium bacteria. Signal 1 (at weak buffering) was correlated with sink formation in root A and induced acidification of B-root medium. This signal is induced by treatment of root A with (i) nodulating rhizobia, (ii) mitogenic Nod factors, (iii) nonmitogenic Nod factors, or (iv) the cytokinin zeatin. Signal 2 (at strong buffering) could only be evoked by treatment with nodulating rhizobia or with mitogenic Nod factors. Most probably, this signal represents the specific AUT signal. Induction of complete AUT appears to require actively dividing nodule cells in nodule primordia, nodule meristems, or both of root A.

Culture Media↗

PubMed1991

Acidic conditions permit effective nodulation of alfalfa by invasion-deficient Rhizobium meliloti exoD mutants.

Rhizobium meliloti exoD mutants are deficient in invasion of alfalfa nodules and, as a consequence, the nodules that exoD strains induce fail to fix nitrogen. These nodules appear to be arrested at the same stage as nodules induced by other exo mutants, which do not make an acidic exopolysaccharide called EPS I, or by ndv mutants, which do not produce a periplasmic cyclic beta(1,2) glucan. However previous genetic and biochemical evidence suggested that the nodule invasion defect of exoD mutants arose from a biochemical deficiency distinct from those of both EPS I-deficient exo mutants and ndv mutants. In this study, we characterize mutant phenotypes of exoD strains in both free-living and symbiotic states. Nodules induced by exoD mutants are generally small and empty of bacteria, and exhibit the same structural features as nodules induced by other invasion-deficient mutants. Putative incipient infection threads were visible in outer cortical cells of these nodules but not in the plant cells in the interior of the nodule. We show that exoD mutants are sensitive to alkaline conditions, ceasing to grow at elevated pH in liquid yeast extract cultures and exhibiting decreased viability in alkaline medium. Interestingly, we find that buffering the plant growth medium at slightly acidic pH (6.0-6.5) restores the ability of exoD mutants to invade alfalfa nodules. exoD mutants are thus alkali sensitive for both free-living and symbiotic phenotypes. This result implies that the nodule invasion defect of exoD mutants arises from their sensitivity to alkaline conditions and, furthermore, that alkaline conditions may obtain in the developing infection thread. The deduced amino acid sequence of ExoD is extremely hydrophobic, suggesting that the protein is membrane associated. We propose models whereby absence of a putative membrane protein might lead to sensitivity to alkaline conditions and consequent arrest of nodule invasion.

Amino Acid Sequence↗

PubMed1993

Proteolysis during Development and Senescence of Effective and Plant Gene-Controlled Ineffective Alfalfa Nodules.

Plant-controlled ineffective root nodules, conditioned by the in1 gene in Medicago sativa L. cv Saranac, undergo premature senescence and have reduced levels of many late nodulins. To ascertain which factors contribute to premature senescence, we have evaluated proteolysis as it occurs throughout the development of ineffective Saranac (in1Sa) and effective Saranac nodules. Cysteine protease activities with acidic pH optimum and enzyme proteins were present in both genotypes. We found that acidic protease activity was low in effective Saranac nodules throughout their development. In contrast, by 2 weeks after inoculation, acid protease activity of in1Sa nodules was severalfold higher than that of Saranac nodules and remained high until the experiment was terminated 8 weeks later. This increase in protease enzyme activity correlated with an increase in protease protein amounts. Increased protease activity and amount in in1Sa nodules was correlated with a decrease in nodule soluble protein. The time at which in1Sa nodules initially showed increased protease activity corresponded to when symbiosis deteriorated. High levels of phosphoenolpyruvate carboxylase (PEPC) protein were expressed in effective nodules by 12 d after inoculation and expression was associated with low proteolytic enzyme activity. In contrast, although PEPC was expressed in in1Sa nodules, PEPC protein was not found 12 d after inoculation and thereafter. Acidic protease from in1Sa nodules could also degrade purified leghemoglobin. These data indicate that premature senescence and low levels of late nodulins in in1Sa nodules can be correlated in part with increased proteolysis.

Journal Article↗

PubMed2004

nip, a symbiotic Medicago truncatula mutant that forms root nodules with aberrant infection threads and plant defense-like response.

To investigate the legume-Rhizobium symbiosis, we isolated and studied a novel symbiotic mutant of the model legume Medicago truncatula, designated nip (numerous infections and polyphenolics). When grown on nitrogen-free media in the presence of the compatible bacterium Sinorhizobium meliloti, the nip mutant showed nitrogen deficiency symptoms. The mutant failed to form pink nitrogen-fixing nodules that occur in the wild-type symbiosis, but instead developed small bump-like nodules on its roots that were blocked at an early stage of development. Examination of the nip nodules by light microscopy after staining with X-Gal for S. meliloti expressing a constitutive GUS gene, by confocal microscopy following staining with SYTO-13, and by electron microscopy revealed that nip initiated symbiotic interactions and formed nodule primordia and infection threads. The infection threads in nip proliferated abnormally and very rarely deposited rhizobia into plant host cells; rhizobia failed to differentiate further in these cases. nip nodules contained autofluorescent cells and accumulated a brown pigment. Histochemical staining of nip nodules revealed this pigment to be polyphenolic accumulation. RNA blot analyses demonstrated that nip nodules expressed only a subset of genes associated with nodule organogenesis, as well as elevated expression of a host defense-associated phenylalanine ammonia lyase gene. nip plants were observed to have abnormal lateral roots. nip plant root growth and nodulation responded normally to ethylene inhibitors and precursors. Allelism tests showed that nip complements 14 other M. truncatula nodulation mutants but not latd, a mutant with a more severe nodulation phenotype as well as primary and lateral root defects. Thus, the nip mutant defines a new locus, NIP, required for appropriate infection thread development during invasion of the nascent nodule by rhizobia, normal lateral root elongation, and normal regulation of host defense-like responses during symbiotic interactions.

Alleles↗

PubMed1983

A rapid regulatory response governing nodulation in soybean.

The number of nodules which develop on the primary root of soybean seedlings (Glycine max L. Merr) after inoculation with Rhizobium japonicum is substantially diminished in the region of the root developmentally 10 to 15 hours younger than the region maximally susceptible to nodulation at the time of inoculation. This rapid inhibition of nodulation has been investigated by inoculating soybean seedlings with rhizobia at two different times, 15 hours apart. Living R. japonicum cells, but not heterologous rhizobia or UV-killed cells of the homologous bacterium, were capable of eliciting the rapid inhibitory response. Nodulation responses to varying inoculum concentrations showed that bacterial dosages could be superoptimal, resulting in reduced nodulation and reduced inhibition of nodulation. When suspensions of R. japonicum were dripped uniformly onto the root surfaces, the degree of inhibition of nodulation in developmentally younger regions of the root was correlated with the number of nodules formed in the older and initially most susceptible region of the root. Nodulation in the developmentally younger region of the root, however, was affected very little if the first inoculum was restricted to contact with root cells in the region initially most susceptible to nodulation. The rapid regulatory response may be an important factor contributing to the clustering of nodules in the crown region of soybean roots in field-grown plants and the sparse nodulation commonly observed in younger regions of the root.

Journal Article↗

PubMed2005

Outcome of small (10-20 mm) arterial phase-enhancing nodules seen on triphasic liver CT in patients with cirrhosis or chronic liver disease.

OBJECTIVE: To determine the outcome of small arterial phase-enhancing nodules, 10-20 mm, seen on serial triphasic liver CT scans in a hepatocellular cancer-screening population. METHODS: Of 58 patients referred for triphasic liver CT, 20 (18 men, 2 women) with 32 nodules formed the study group. Each patient in the study group had at least two CT scans, a minimum of 3 months follow-up, at least one nodule measuring 10-20 mm, no prior diagnosis of hepatocellular carcinoma, and no nodule greater than 20 mm typical of hepatocellular carcinoma at the time of the first CT. Serial CT scans were reviewed by an abdominal imaging radiologist who classified the nodules as stable, decreasing, or increasing in size. RESULTS: A mean of six CT studies (range 2-10) were performed for each patient with a mean follow-up of 25 months (range 4-47 months). Of 32 nodules, 14 (44%) were stable, 9 (28%) decreased, and 9 (28%) increased in size. Nodules that increased in size were treated as hepatocellular carcinoma: six were hepatocellular carcinoma, two were biopsy negative but showed recurrent tumor after radiofrequency ablation, and one was a high-grade dysplastic nodule. Mean doubling time for these nine nodules was 5.7 months (range 2.3-10.8 months). CONCLUSIONS: Most small (10-20 mm) arterial phase-enhancing nodules seen on triphasic liver CT are not hepatocellular carcinoma. Serial CT is useful to guide management in these patients. Growth of small arterial phase-enhancing nodules can be used as an indicator that the nodule should be treated as hepatocellular carcinoma.

Aged↗