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PubMed1992

Alfalfa root nodule phosphoenolpyruvate carboxylase: characterization of the cDNA and expression in effective and plant-controlled ineffective nodules.

Phosphoenolpyruvate carboxylase (PEPC) plays a key role in N2 fixation and ammonia assimilation in legume root nodules. The enzyme can comprise up to 2% of the soluble protein in root nodules. We report here the isolation and characterization of a cDNA encoding the nodule-enhanced form of PEPC. Initially, a 2945 bp partial-length cDNA was selected by screening an effective alfalfa nodule cDNA library with antibodies prepared against root nodule PEPC. The nucleotide sequence encoding the N-terminal region of the protein was obtained by primer-extension cDNA synthesis and PCR amplification. The complete amino acid sequence of alfalfa PEPC was deduced from these cDNA sequences and shown to bear striking similarity to other plant PEPCs. Southern blots of alfalfa genomic DNA indicate that nodule PEPC is a member of a small gene family. During the development of effective root nodules, nodule PEPC activity increases to a level that is 10- to 15-fold greater than that in root and leaf tissue. This increase appears to be the result of increases in amount of enzyme protein and PEPC mRNA. Ineffective nodules have substantially less PEPC mRNA, enzyme protein and activity than do effective nodules. Maximum expression of root nodule PEPC appears to be related to two signals. The first signal is associated with nodule initiation while the second signal is associated with nodule effectiveness. Regulation of root nodule PEPC activity may also involve post-translational processes affecting enzyme activity and/or degradation.

Amino Acid Sequence↗

PubMed1985

Nodules are induced on alfalfa roots by Agrobacterium tumefaciens and Rhizobium trifolii containing small segments of the Rhizobium meliloti nodulation region.

Regions of the Rhizobium meliloti nodulation genes from the symbiotic plasmid were transferred to Agrobacterium tumefaciens and Rhizobium trifolii by conjugation. The A. tumefaciens and R. trifolii transconjugants were unable to elicit curling of alfalfa root hairs, but were able to induce nodule development at a low frequency. These were judged to be genuine nodules on the basis of cytological and developmental criteria. Like genuine alfalfa nodules, the nodules were initiated from divisions of the inner root cortical cells. They developed a distally positioned meristem and several peripheral vascular bundles. An endodermis separated the inner tissues of the nodule from the surrounding cortex. No infection threads were found to penetrate either root hairs or the nodule cells. Bacteria were found only in intercellular spaces. Thus, alfalfa nodules induced by A. tumefaciens and R. trifolii transconjugants carrying small nodulation clones of R. meliloti were completely devoid of intracellular bacteria. When these strains were inoculated onto white clover roots, small nodule-like protrusions developed that, when examined cytologically, were found to more closely resemble roots than nodules. Although the meristem was broadened and lacked a root cap, the protrusions had a central vascular bundle and other rootlike features. Our results suggest that morphogenesis of alfalfa root nodules can be uncoupled from infection thread formation. The genes encoded in the 8.7-kilobase nodulation fragment are sufficient in A. tumefaciens or R. trifolii backgrounds for nodule morphogenesis.

Conjugation, Genetic↗

PubMed2000

Analysis of ENOD40 expression in alb1, a symbiotic mutant of Lotus japonicus that forms empty nodules with incompletely developed nodule vascular bundles.

The alb1 mutant of Lotus japonicus (Ljsym74) forms empty nodules in which most of the bacteria remain in abnormally enlarged infection threads and fail to enter the host plant cells. The alb1 mutant was also found to be defective in differentiation of ramified nodule vascular bundles; only a single vascular bundle differentiates at the proximal end of the alb1 nodules and it fails to differentiate further. Histochemical analysis using fluorescein-conjugated wheat-germ agglutinin (F-WGA) indicated that the mutation in the ALB1 gene specifically affects the differentiation of vascular bundles in nodules. Analysis of nodulin gene expression revealed that the expression of an early nodulin gene, ENOD40, was very low in alb1 nodules. At early developmental stages of alb1 nodules, the pattern of ENOD40 transcription was essentially the same as that in wild-type nodules; transcripts were localized in dividing cortical cells and in the pericycle of the root stele opposite nodule primordia, as in wild-type nodules. However, mature alb1 nodules exhibited very weak or no expression of ENOD40 in the peripheral cells of the undeveloped nodule vascular bundle. The ENOD40 expression pattern in alb1 nodules is distinct from that in another ineffective mutant, fen1 (Ljsym76), in which ENOD40 expression persists prior to premature senescence. These findings lead us to speculate that ENOD40 may play a role in the differentiation of nodule vascular bundles.

Fabaceae↗

PubMed2002

Competitive nodulation blocking of cv. Afghanistan pea is related to high levels of nodulation factors made by some strains of Rhizobium leguminosarum bv. viciae.

Cultivar Afghanistan peas are resistant to nodulation by many strains of Rhizobium leguminosarum bv. viciae but are nodulated by strain TOM, which carries the host specificity gene nodX. Some strains that lack nodX can inhibit nodulation of cv. Afghanistan by strain TOM. We present evidence that this "competitive nodulation-blocking" (Cnb) phenotype may result from high levels of Nod factors inhibiting nodulation of cv. Afghanistan peas. The TOM nod gene region (including nodX) is cloned on pIJ1095, and strains (including TOM itself) carrying pIJ1095 nodulate cv. Afghanistan peas very poorly but can nodulate other varieties normally. The presence of pIJ1095, which causes increased levels of Nod factor production, correlates with Cnb. Nodulation of cv. Afghanistan by TOM is also inhibited by a cloned nodD gene that increases nod gene expression and Nod factor production. Nodulation of cv. Afghanistan can be stimulated if nodD on pIJ1095 is mutated, thus severely reducing the level of Nod factor produced. Repression of nod gene expression by nolR eliminates the Cnb phenotype and can stimulate nodulation of cv. Afghanistan. Addition of Nod factors to cv. Afghanistan roots strongly inhibits nodulation. The Cnb+ strains and added Nod factors inhibit infection thread initiation by strain TOM. The sym2A allele determines resistance of cv. Afghanistan to nodulation by strains of R. leguminosarum bv. viciae lacking nodX. We tested whether sym2A is involved in Cnb by using a pea line carrying the sym2A region introgressed from cv. Afghanistan; nodulation in the introgressed line was inhibited by Cnb+ strains. Therefore, the sym2A region has an effect on Cnb, although another locus (or loci) may contribute to the stronger Cnb seen in cv. Afghanistan.

Bacterial Proteins↗

PubMed1988

Expression of nodule-specific genes in alfalfa root nodules blocked at an early stage of development.

To help dissect the molecular basis of the Rhizobium-legume symbiosis, we used in vitro translation and Northern blot analysis of nodule RNA to examine alfalfa-specific genes (nodulins) expressed in two types of developmentally defective root nodules elicited by Rhizobium meliloti. Fix- nodules were elicited by R. meliloti nif mutants; these nodules were invaded by rhizobia and contained differentiated bacteroids. 'Empty' nodules were elicited by R. meliloti exo and ndv mutants and by Agrobacterium tumefaciens strains carrying the R. meliloti nod genes; these nodules contained a nodule meristem but lacked infection threads, intracellular bacteria, and bacteroids. Fix- nodules contained a spectrum of nodulins similar to wild-type nodules. In contrast, only two nodulins, Nms-30 and a nodulin homologous to ENOD2 of soybean, were detected in empty nodules. Although R. meliloti ndv and exo mutants elicited nodules with the same defective phenotype, ndv and exo mutants (except for exoC mutants) had distinct biochemical phenotypes. R. meliloti ndvA and ndvB mutants were deficient in cyclic glucan production but not the acidic exopolysaccharide; the converse was true for exoA, exoB, and exoF mutants. exoC mutants were defective in both exopolysaccharide and cyclic glucan biosynthesis. Our results support the model that the R. meliloti nod genes produce a signal that results in nodule meristem induction. Both the exopolysaccharide and cyclic glucan, however, appear to act at the next step in the developmental process and are involved in the production of a signal (or structure) that allows infection thread formation and invasion of the nodule.

Amino Acid Sequence↗

PubMed2001

Siderotic nodules in the cirrhotic liver at MR imaging with explant correlation: no increased frequency of dysplastic nodules and hepatocellular carcinoma.

PURPOSE: To determine the sensitivity of magnetic resonance (MR) imaging for detection of siderotic nodules in patients with cirrhosis and whether the frequency of hepatocellular carcinoma (HCC) and dysplastic nodules is greater if siderotic nodules are present. MATERIALS AND METHODS: MR imaging (1.5 T) was performed within 0-117 days (mean, 30 days) before liver transplantation in 77 patients. Two readers retrospectively evaluated gradient-echo (GRE) (echo time [TE], > or = 9 and 4-5 msec) and turbo short inversion time inversion-recovery or T2-weighted images for low-signal-intensity nodules. Whole-explant pathologic correlation was available in every case. RESULTS: At explantation, 28 (36%) of 77 patients had HCC, 25 (32%) had dysplastic nodules, and nine (12%) had both; 35 (45%) patients had siderotic nodules. The sensitivity of GRE imaging with 9-msec or longer TE for the detection of siderotic nodules was 80% (28 of 35) but decreased to 31% (11 of 35) with 4-5-msec TE. Frequency of HCC was not significantly higher (P =.27) in patients with (43% [15 of 35]) than in patients without (31% [13 of 42]) siderotic nodules. Frequency of dysplastic nodules also was not significantly higher (P =.42) in patients with (37% [13 of 35]) than in patients without (29% [12 of 42]) siderotic nodules. CONCLUSION: Sensitivity of MR imaging for the detection of siderotic nodules was improved with use of GRE pulse sequences with longer TEs of 9 msec or greater (80%) versus 4-5 msec (31%); however, there was no significant increased frequency of HCC or dysplastic nodules in patients with pathologically proved siderotic nodules.

Adult↗

PubMed1996

Cold thyroid nodule reduction with L-thyroxine can be predicted by initial nodule volume and cytological characteristics.

In a previous study we demonstrated that a 1-yr treatment with L-T4 induces substantial nodule volume reduction (> or = 50%) in approximately 40% of patients with a benign solitary cold thyroid nodule. The present prospective study investigated whether it is possible to identify, before starting L-T4 treatment, nodules with a high probability to shrink in response to L-T4. We recorded several clinical and cytological features in a continuous series of 42 patients with a cold nodule and related them to the nodule volume response to 1-yr treatment with L-T4. Fisher discriminant analysis showed that a combination of some cytological features (colloid, degenerative changes, cellular hyperplasia, and fibrosis) and initial nodule volume can be used for predicting nodule volume reduction. In fact, although only 33% of all nodules shrank, 62% of colloid nodules and 57% of small degenerative nodules shrank. None of the hyperplastic or fibrotic nodules shrank. These results were validated in a different retrospective series of 46 patients and allowed us to predict nodule reduction in over 80% of the cases.

Humans↗

PubMed1996

Sucrose synthase and enolase expression in actinorhizal nodules of Alnus glutinosa: comparison with legume nodules.

Two different types of nitrogen-fixing root nodules are known- actinorhizal nodules induced by Frankia and legume nodules induced by rhizobia. While legume nodules show a stem-like structure with peripheral vascular bundles, actinorhizal nodule lobes resemble modified lateral roots with a central vascular bundle. To compare carbon metabolism in legume and actinorhizal nodules, sucrose synthase and enolase cDNA clones were isolated from a cDNA library, obtained from actinorhizal nodules of Alnus glutinosa. The expression of the corresponding genes was markedly enhanced in nodules compared to roots. in situ hybridization showed that, in nodules, both sucrose synthase and enolase were expressed at high levels in the infected cortical cells as well as in the pericycle of the central vascular bundle of a nodule lobe. Legume sucrose synthase expression was studied in indeterminate nodules from pea and determinate nodules from Phaseolus vulgaris by using in situ hybridization.

Actinomycetaceae↗

PubMed1988

Nodulin gene expression in effective alfalfa nodules and in nodules arrested at three different stages of development.

Nodulin gene expression was analyzed in effective and ineffective root nodules of alfalfa (Medicago sativa L. cv Iroquois) elicited by three different Rhizobium meliloti mutants: an exoB mutant having defective acidic exopolysaccharide that does not fluoresce on plates containing the fluorescent brightener Calcofluor; fix21, a spontaneous mutant that has defective lipopolysaccharide and is Calcofluor bright; and a Rhizobium mutant resulting from a Tn5 insertion in the nifH gene of the nif operon. The ineffective nodules elicited by these various mutant rhizobia are blocked at different stages of nodule development and have unique phenotypes. A distinctive pattern of nodulin gene expression as determined by in vitro translations of total nodule RNA characterizes each nodule phenotype. Seventeen nodulins are found in effective nodules including five leghemoglobins. Only one nodulin gene is expressed in the bacteria-free nodules elicited by the exoB mutant. Other nodulin genes (leghemoglobin and nine others) are expressed in fix21-induced nodules. The genes for nodule-enhanced glutamine synthetase as well as for all the other nodulins are expressed in nodules induced by the nifH mutant. The expression of genes for the nodulins, including leghemoglobin, is independent of the nitrogen-fixing ability of the nodule and appears to correlate with the differentiation of densely cytoplasmic host cells in the nodule and, to some extent, with bacterial release from infection threads.

Journal Article↗

PubMed2004

Unique hypervascular nodules in alcoholic liver cirrhosis: identical to focal nodular hyperplasia-like nodules?

BACKGROUND/AIMS: Currently, focal nodular hyperplasia (FNH)-like nodules in cirrhotic liver is spotlighted. Unique hypervascular nodules mimicking FNH-like nodule in alcoholic liver cirrhosis were clinicopathologically clarified. METHODS: Six resected and six biopsy cases of small hypervascular nodules found in alcoholic cirrhosis were studied clinicopathologically. RESULTS: All cases were male and consumed 90-150 g/day of ethanol for longer than 20 years, and hepatitis virus markers were negative. The nodules, 9-21 mm in diameter, were detected by ultrasonography during follow-up of alcoholic cirrhosis, and showed hypervascularity on angiography. Six patients were diagnosed as hepatocellular carcinoma and six were as hyperplastic nodule by biopsy, and the former six cases received partial hepatectomy. All of the resected nodules were completely or incompletely encapsulated. Histologically, all resected and biopsy nodules showed moderate increase of cell-density with an irregular trabecular pattern, and scar-like fibrosis with anomalous blood vessels, and unpaired arteries. All nodules showed marked or mild iron deposits in hepatocytes and/or kupffer cells, and a diffuse capillarization of the sinusoids. CONCLUSIONS: The nodules in the present series seem to fall in the same category as FNH-like nodules in cirrhotic liver, and should be taken account in screening programs including patients with alcoholic cirrhosis.

Adult↗

PubMed2003

Quick and reversible inhibition of soybean root nodule growth by nitrate involves a decrease in sucrose supply to nodules.

The upper part of a nodulated soybean root hydroponically cultured in a glass bottle was monitored using a computer microscope under controlled environmental conditions, and the diameter of individual nodules was measured from 10-24 d after planting. The diameter of a root nodule attached to the primary root increased from 1 mm to 6 mm for 2 weeks under nitrogen-free conditions. The increase in diameter of the nodules was almost completely stopped after 1 d of supplying 5 mM nitrate, and was due to the cessation of nodule cell expansion. However, nodule growth quickly returned to the normal growth rate following withdrawal of nitrate from the solution. The reversible depression of nodule growth by nitrate was similar to the restriction of photoassimilate supply by continuous dark treatment for 2 d followed by normal light/dark conditions. In addition, the inhibitory effect of nitrate was partially alleviated by the addition of 3% (w/v) sucrose to the medium. Plant leaves were exposed to (11)C or (14)C-labelled carbon dioxide to investigate the effects of 5 mM nitrate on the translocation and distribution of photosynthates to nodules and roots. Supplying 5 mM nitrate stimulated the translocation rate and the distribution of labelled C in nitrate-fed parts of the roots. However, the (14)C partitioning to nodules decreased from 9% to 4% of total (14)C under conditions of 5 mM nitrate supply. These results indicate that the decrease in photoassimilate supply to nodules may be involved in the quick and reversible nitrate inhibition of soybean nodule growth.

Biological Transport↗

PubMed2003

Salicylic acid inhibits indeterminate-type nodulation but not determinate-type nodulation.

LCOs (lipochitin oligosaccharides, Nod factors) produced by the rhizobial symbiote of Vicia sativa subsp. nigra (vetch, an indeterminate-type nodulating plant) are mitogenic when carrying an 18:4 acyl chain but not when carrying an 18:1 acyl chain. This suggests that the 18:4 acyl chain specifically contributes to signaling in indeterminate-type nodulation. In a working hypothesis, we speculated that the 18:4 acyl chain is involved in oxylipin signaling comparable to, for example, signaling by derivatives of the 18:3 fatty acid linolenic acid (the octadecanoid pathway). Because salicylic acid (SA) is known to interfere with oxylipin signaling, we tested whether nodulation of vetch could be affected by addition of 10(-4) M SA. This concentration completely blocked nodulation of vetch by Rhizobium leguminosarum bv. viciae and inhibited the mitogenic effect of 18:4 LCOs but did not affect LCO-induced root-hair deformation. SA did not act systemically, and only biologically active SA derivatives were capable of inhibiting nodule formation. SA also inhibited R. leguminosarum bv. viciae association with vetch roots. In contrast, addition of SA to Lotus japonicus (a determinate-type nodulating plant responding to 18:1 LCOs) did not inhibit nodulation by Mesorhizobium loti. Other indeterminate-type nodulating plants showed the same inhibiting response toward SA, whereas SA did not inhibit the nodulation of other determinate-type nodulating plants. SA may be a useful tool for studying fundamental differences between signal transduction pathways of indeterminate- and determinate-type nodulating plants.

Fabaceae↗

PubMed1983

Phytohormones, Rhizobium Mutants, and Nodulation in Legumes : III. Auxin Metabolism in Effective and Ineffective Pea Root Nodules.

High specific activity [(3)H]indole-3-acetic acid (IAA) was applied to the apical bud of intact pea (Pisum sativum L. cv Greenfeast) plants. Radioactivity was detected in all tissues after 24 hours. More radioactivity accumulated in the nodules than in the parent root on a fresh weight basis and more in effective (nitrogen-fixing) nodules than in ineffective nodules (which do not fix nitrogen).For most samples, thin layer chromatography revealed major peaks of radioactivity at the R(F) values of IAA and indole-3-acetylaspartic acid (IAAsp) and further evidence of the identity of these compounds was obtained by chromatography in other systems. Disintegrations per minute due to IAA per unit fresh weight were significantly greater for root than for nodule tissue, but were not significantly different for effective and ineffective nodules. Radioactivity due to IAAsp, expressed both on a percentage basis and per unit fresh weight, was significantly greater for nodule than for root tissue and significantly greater for the effective nodules than for the ineffective nodules. When [(3)H]IAA was applied to effective nodules, IAAsp was the dominant metabolite in the nodule. The data suggest that metabolism of auxins may be important for the persistence of a functional root nodule.

Journal Article↗

PubMed1986

Effect of lectin on nodulation by wild-type Bradyrhizobium japonicum and a nodulation-defective mutant.

The nodulation characteristics of wild-type Bradyrhizobium japonicum USDA 110 and mutant strain HS111 were examined. Mutant strain HS111 exhibits a delayed-nodulation phenotype, a result of its inability to initiate successful nodulation promptly following inoculation of the soybean root. Previously, we showed that the defect in initiation of infection leading to subsequent nodulation which is found in HS111 can be phenotypically reversed by pretreatment with soybean root exudate or soybean seed lectin. This effect is not seen after pretreatment with root exudates and lectins obtained from other plant species. Treatment of strain HS111 with as little as 10 soybean seed lectin molecules per bacterium (3.3 X 10 (-12) M) resulted in enhancement of nodule formation. Pretreatment of wild-type B. japonicum USDA 110 with soybean root exudate or seed lectin increased nodule numbers twofold on 6-week-old plants. Wild-type strain USDA 110 cells inoculated at 10(4) cells per seedling exhibited a delay in initiation of infection leading to subsequent nodulation. Wild-type cells pretreated in soybean root exudates or seed lectin did not exhibit a delay in nodulation at this cell concentration. Mutant strain HS111 pretreated in seed lectin for 0 or 1 h, followed by washing with the hapten D-galactose to remove the lectin, exhibited a delay in initiation of nodulation. Phenotypic reversal of the delayed-nodulation phenotype exhibited by strain HS111 was seen if incubation was continued for an additional 71 h in plant nutrient solution following 1 h of lectin pretreatment. Reversal of the delayed-nodulation phenotype of HS111 through lectin pretreatment was prevented by chloramphenicol or rifampin.(ABSTRACT TRUNCATED AT 250 WORDS)

Chloramphenicol↗

PubMed1994

Lymphokine-activated killer cells induce differentiation in MCF-7 breast carcinoma nodules but not in mastosis nodules maintained in three-dimensional culture.

In order to better understand the interaction between activated lymphocytes and breast carcinoma cells, we studied the degree of infiltration, the membrane contacts established and their cytostatic and cytolytic effects in MCF-7 nodules maintained in three-dimensional culture. A comparison was made with nodules of a nonmalignant, immortalized mastosis cell line. Histological, immunohistochemical and electron microscopical observations were performed as well as DNA synthesis measurements in the two components of the coculture. The lymphokine-activated killer (LAK) cells adhered more frequently to the carcinoma nodules than to the mastosis nodules. They actively penetrated into both of them. The penetration remained peripheral, and only a few cells migrated more deeply. The LAK cells established close cell-to-cell contacts with the two types of nodules, and intercellular gaps were formed: damaged cells could be seen near the activated killer cells. In MCF-7 nodules, a 5-fold inhibition of proliferation occurred, and extensive necrotic zones developed; this was accompanied by a general tendency for glandular redifferentiation. In mastosis nodules, necrosis also developed but no cell differentiation occurred and proliferation was less inhibited (2 times). Interleukin-2 alone enhanced DNA synthesis in mastosis nodules but had no effect on MCF-7 nodules, and no extending necrosis could be seen in both types of nodules. The cytolytic effects of LAK cells combined with their redifferentiating effect in MCF-7 breast carcinoma nodules may be a useful indication for further breast cancer therapy research.

Adenocarcinoma↗

PubMed1996

[Thoracoscopic wedge resection of small pulmonary nodules--evaluation of Endofinger and colored collagen injection techniques for localization of pulmonary nodules].

We analyzed problems occurring during thoracoscopic resection of small pulmonary nodules less than 2.0 cm in size and evaluated the Endofinger and colored collagen injection techniques, which are new methods for localization of pulmonary nodules. The Endofinger is a device for thoracoscopic palpation and the colored collagen is a long-lasting point marker, composed of 1.0% athelocollagen, methylene blue and contrast medium. Twenty five consecutive patients (male: female = 13:12, mean age 59.0 years) underwent thoracoscopic wedge excision of pulmonary nodules. The mean diameter of the nodules was 1.3 cm (range: 0.4-2.0 cm) and the mean distance from the pleural surface to the nodules, as assessed by CT scan, was 1.1 cm (range: 0-3.8 cm). Methods of pulmonary nodule identification were thoracoscopic inspection only (4 cases), palpation through min-thoracotomy (13 cases), Endofinger (2 cases) and Endofinger with colored collagen injection guided by CT scan (6 cases). In all cases where location was difficult to identify, the nodule diameter was less than 1 cm and the distance from the pleural surface to the nodule was greater than 1 cm. The Endofinger and colored collagen injection techniques have made it easier to localize small pulmonary nodules, decreasing the frequency of cases where additional thoracotomy is necessary. Seven of 25 nodules were revealed to be so-called early peripheral lung cancers, but no relapses were found in any of these cases following pulmonary resection. The new Endofinger and colored collagen injection techniques are useful in the localization of small pulmonary nodules, making thoracoscopic wedge resection of help in early diagnosis and treatment of pulmonary malignancy.

Biopsy↗

PubMed2000

Large-needle aspiration biopsy for the preoperative selection of palpable thyroid nodules diagnosed by fine-needle aspiration as a microfollicular nodule or suspected cancer.

The palpable thyroid nodules with a fine-needle aspiration (FNA) diagnosis of microfollicular nodule or suspected cancer usually are excised; however, most of them are proved benign by postoperative histologic examination. We reviewed the clinical and pathologic data for patients with thyroid nodules with an FNA diagnosis of microfollicular nodule or suspected cancer; nodules also were examined by large-needle aspiration biopsy (LNAB) to assess whether the distinction achieved by LNAB into pure microfollicular or mixed microfollicular-macrofollicular nodules could be used preoperatively to better predict malignancy. One hundred fourteen nodules of this type were excised. The prevalence of cancer was 22% (14/63) among the microfollicular and 4% (2/51) among the microfollicular-macrofollicular nodules at LNAB. These data indicate that histologic examination of the LNAB specimen can be used for preoperative selection of thyroid nodules diagnosed by FNA as a microfollicular nodule or suspected cancer.

Adenocarcinoma, Follicular↗

PubMed1996

[Detectability of simulated nodules on chest phantom by Fuji computed radiography: comparison of different nodule sizes, configurations and tube voltages].

The detectability of simulated nodules placed on a chest phantom and shown on FCR images has been studied. Different tube voltages (130 kVp, 100 kVp), presence or absence of compensation filter, various sites and different sizes (5 mm/10 mm) and configurations (spherical or broad based) of the nodule were examined. 112 FCR chest phantom images were evaluated by ten radiology specialists utilizing ROC analysis. The detection rate for nodules was influenced in general by the site. The detection rate was as follows in decreasing order: intercostal, overlaid with one rib, two ribs, diaphragm and heart. Detection of nodules of 10 mm in height was mainly influenced by the density of the lung where the nodule was located, whereas that of nodules of 5 mm in height was more dependent on the site of the nodule, probably greatly influenced by the amount of structure mottle. Spherical nodules of 5 mm in height were more frequently recognized than the broad-based ones. High kVp (130 kVp) resulted in a higher detection rate for both sizes of nodules than low kVp (100 kVp). Detection of spherical nodules overlying the heart or diaphragm was improved with the use of a compensation filter.

Humans↗