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At least 19 recordsLinked to original sources
PubMed1977

Enzymes of nitrogen metabolism in legume nodules. Purification and properties of NADH-dependent glutamate synthase from lupin nodules.

An NADH-dependent glutamate synthase has been purified 500-fold from the plant cytoplasm fraction of Lupinus angustifolius nodules. It consists of a single polypeptide chain, Mr 235000. The optimum pH is 8.5, at which Km values for 2-oxoglutarate, glutamine and NADH are 39 micrometer, 400 micrometer and 1.3 micrometer respectively. The catalytic centre activity is of the order of 70 s-1 and is independent of pH between 6.5 and 9.5. Glutamate synthase is inhibited by glutamic acid, oxaloacetic acid, aspartic acid and asparagine, all competitive with 2-oxoglutarate; and by NAD+, which is competitive with NADH. There is evidence of two flavine prosthetic groups per enzyme molecule.

Glutamate Synthase↗
PubMed1979

Recombination nodules and synaptonemal complex in recombination-defective females of Drosophila melanogaster.

The cytological effects of mutant alleles of the mei-9, mei-218, and mei-41 loci during prophase I have been examined by electron microscopy. None of these mutants affect synaptonemal complex structure, continuity, or temporal behavior. Both the precondition-defective mutants mei-218 and mei-41 affect both number and morphology of spherical recombination nodules and apparently affect at least the numbers of ellipsoidal recombination nodules, whereas in the exchange-defective mutant mei-9 the numbers and morphologies of both ellipsoidal and spherical recombination nodules are normal. The parallel effects of mei-218 and mei-41 on meiotic recombination and on recombination nodules indicate that spherical recombination nodules at least mark the site of exchange events; the effects of these mutants on nodule morphology suggest that the nodule performs an active role in the recombination process. The nodule phenotype of mei-9 indicates that spherical nodules are present, and presumably functioning, well before the concluding stages of the recombination event. The parallel effects of all 3 mutants on ellipsoidal and spherical nodules indicate that these are indeed related structures but does not ellucidate the nature of the relationship. It is suggested that all aspects of meiotic recombination are under the aegis of recombination nodules.

Animals↗
PubMed1975

Hormone dependence and estradiol receptors in the D series of mammary nodule outgrowth lines and tumors.

Preneoplastic mammary nodule outgrowth lines were examined for their ability to grow and produce tumors in ovariectomized BALB/c mice. In addition, these nodule outgrowth lines and tumors derived from them were investigated for cytoplasmic estrogen receptor proteins by qualitative and quantitative techniques. Early ovariectomy, performed within 4 weeks after transplantation, slightly delayed but did not permanently block the ability of three different nodule lines to completely fill the fat pad with nodule tissue. Ovariectomy performed later than 4 weeks after transplantation or adrenalectomy performed early or late had no effect on nodule growth. Neither early nor late ovariectomy or adrenalectomy had an effect on the maintenance of the nodule alveolar phenotype. Ovariectomy performed 3 weeks after transplantation had little effect on the tumor potential of the low oncogenic line D1 or the high oncogenic line D2. Samples of nodule outgrowths transplanted from ovariectomized mice responded to a chemical carcinogen in a similar manner, as did nodule outgrowths transplanted from control experiments. Thus, the altered hormonal environmenment in ovariectomized mice apparently did not select for subpopulations of nodule cells with altered tumorigenic potentials. The ovarian independence of the nodule lines and tumors derived from them was correlated with a very low level of cytoplasmic estrogen receptor. These results, along with other data, illustrate the nature of the independence on ovarian hormonal control for tumorigenesis in these mammary tumor virus-free nodule lines.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2026

Estimating Rhizobial Fitness During Legume Symbiosis: Enriching Viable Undifferentiated Bacteria from Root Nodules.

Advances in understanding the evolutionary ecology of the rhizobia-legume mutualism have been constrained by methodological limitations in efficiently measuring relative strain frequencies alongside measurements of absolute population sizes of rhizobia living in nodules. To examine strain competition in natural and agricultural ecosystems that harbor multiple strains of rhizobia, an increasing number of manipulative and observational studies have recently begun to examine dozens or hundreds of strains simultaneously. Assessing the competitive fitness of multiple strains in legume nodules requires, first, processing pools of dozens to hundreds of nodules to overcome the stochasticity of nodule formation; second, focusing on the reproductively viable rhizobial population, since this trait represents rhizobia's reproductive success in nodules and is pivotal for evolutionary interpretations. Our approach has been optimized in the Medicago truncatula-Sinorhizobium meliloti system, where rhizobia induce the formation of indeterminate nodules that harbor two subpopulations: terminally-differentiated bacteroids and undifferentiated rhizobia that retain reproductive viability. This protocol has also been used for other legumes with terminally-differentiated bacteroids, such as pea and vetch, as well as for those with non-terminally differentiated bacteroids, such as soybean and cowpeas. The protocol we present enables rapid and reproducible homogenization of pools containing hundreds of nodules using a tissue homogenizer. We also enrich for undifferentiated rhizobia using two centrifugation steps: first, a low-speed centrifugation to deplete nodule debris and large, endoreduplicated, terminally-differentiated bacteroids, followed by a high-speed centrifugation to pellet the remaining undifferentiated rhizobia. The pellet can later be used for DNA extraction, followed by whole-genome or amplicon sequencing, and then downstream analysis to estimate strain fitness. Finally, we include an optional step for a reliable, reproducible system for nodule imaging, which is especially useful for quantifying nodule abundance and studying morphological variation. ​.

Symbiosis↗
PubMed2024

The Growth of Screening-Detected Pure Ground-Glass Nodules Following 10 Years of Stability.

BACKGROUND: It remains uncertain for how long pure ground-glass nodules (pGGNs) detected on low-dose CT (LDCT) imaging should be followed up. Further studies with longer follow-up periods are needed to determine the optimal follow-up duration for pGGNs. RESEARCH QUESTION: What is the percentage of enlarging nodules among pGGNs that have remained stable for 10 years? STUDY DESIGN AND METHODS: This was a retrospective cohort study originating from participants with pGGNs detected on LDCT scans between 1997 and 2006 whose natural courses were reported in 2013. We re-analyzed all the follow-up data until July 2022. The study participants were followed up per our institutional guidelines until they were no longer a candidate for definitive treatment. The growth of the pGGNs was defined as an increase in the diameter of the entire nodule by ≥ 2 mm or the appearance of new solid portions within the nodules. RESULTS: A total of 89 patients with 135 pGGNs were followed up for a median of 193 months. Of 135 pGGNs, 23 (17.0%) increased in size, and the median time to the first detection of a size change was 71 months. Of the 135 pGGNs, 122 were detected on the first LDCT scan and 13 were newly detected on the follow-up CT scan. An increase in size was observed within 5 years in 8 nodules (34.8%), between 5 and 10 years in 12 nodules (52.2%), and after 10 years in three nodules (13.0%). Fifteen nodules were histologically confirmed as adenocarcinoma by surgery. Among the 76 pGGNs stable for 10 years, 3 (3.9%) increased in size. INTERPRETATION: Among pGGNs that remained stable for 10 years, 3.9% eventually grew, indicating that some pGGNs can grow even following a long period of stability. We suggest that pGGNs may need to be followed up for > 10 years to confirm growth.

Humans↗
PubMed1977

Physiological and biochemical studies on senescing tap root nodules of soybeans.

Senescence of soybean (Glycine max L. Merr.) tap root nodules was investigated by comparing changes in various physiological and biochemical activities with changes in capacity to fix nitrogen. Field-grown Beeson and Calland varieties of soybeans of various ages were sources of tap root nodules. With both varieties, the number of tap root nodules per plant remained constant between 56 and 86 days after planting but fresh weight, dry weight, and mass of tap root nodules increased duing this period. Nitrogen (C2H2)fixation by attached tap root nodules was maximum on a fresh weight, dry weight, or nitrogen basis about 56 days after planting for either variety. Metabolic activities of bacteroids as measured by carbon dioxide evolution from glucose and succinate did not appear to vary among nodules of different ages. There was also no indication of mobilization or deposition or deposition of iron, molybdenum, calcium, zinc, and nitrate in aging tap root nodules. Nitrate levels in the aerial portion of the plants decreased significantly after the initial decline in acetylene reduction. Nicotinamide deamidase activity in the cytosol and in extracts of bacteroids did not change significantly as tap root nodules aged. However, significant and consistent changes were observed in initial pH values of nodule breis and the initial decline occurred before (Calland) or concurrently (Beeson) with the initial decline of nitrogen fixation.

Bacteria↗
PubMedDate not supplied

[Diagnostic value of thermography and Tc 99m bleomycin scintigraphy for nodules of the thyroid (author's transl)].

The combined interest of thermography and 99mTc Bleomycin scintigraphy in the differential diagnosis of a cold thyroid nodule was evaluated in 86 patients. In all cases a histological examination was performed. Of the 30 malignant nodules (clinically suspect and solitary nodules) 21 (70%) showed concentrations of 99mTc Bleomycin while only 7 of the 12 solitary malignant nodules did so. Among the 54 benign nodules the false positive rate was 54%. Thermography was positive in 26 (87%) of the 30 malignant nodules and in only 8 (67%) of the 12 solitary malignant nodules. For the 54 benign nodules the false positive rate was 72%. The combined results of the study do not provide any improvement in diagnostic accuracy. Thus it can be said that applications of 99mTc Bleomycin and thermography in the diagnosis of solitary hypofixiant nodules are of limited value.

Bleomycin↗
PubMed1978

Comparison of computed and conventional whole lung tomography in detecting pulmonary nodules: a prospective radiologic-pathologic study.

Whole lung computed tomography (CT) was performed on 25 patients with clinical diagnoses including osteogenic sarcoma. Ewing's sarcoma, rhabdomyosarcoma, fibrosarcoma, and melanoma in whom conventional tomography had revealed from one to four parenchymal nodules in one lung deemed resectable for either staging or treatment purposes. Thoracotomy was performed within 3 weeks after conventional and computed whole lung tomography. All palpable nodules were resected, measured at the time of surgery, mapped by anatomic segment, and submitted for individual histologic evaluation. CT defined more nodules than conventional tomography in 48% of cases. The additional nodules were usually pleural or subpleural and 3--6 mn in diameter. CT identified 78% of all resected nodules greater than 3 mm in diameter, compared to 59% using conventional tomography. CT was also of value in detecting bilateral nodules earlier than conventional tomography and in documenting small nodule growth on successive examination. However, 60% of the additional nodules defined by CT and resected proved to be benign granulomas and pleural-based nodes at thoracotomy.

Adolescent↗
PubMed1976

A relative deficiency of cytochrome P-450 and aryl hydrocarbon [benzo(a)pyrene] hydroxylase in hyperplastic nodules induced by 2-acetylaminofluorene in rat liver.

The concentrations of cytochrome P-450 and the activities of aryl hydrocarbon [benzo(a)pyrene] hydroxylase (AHH) and reduced nicotinamide adenine dinucleotide phosphate-cytochrome c reductase were measured in early (gray-white) and remodeled (brown) hyperplastic nodules induced in the livers of rats with 2-acetylaminofluorene and were compared to the values in control livers and in the liver surrounding the nodules. Cytochrome P-450 content of early (14 weeks) hyperplastic nodules is 30% of the activity of untreated control livers and 48% of the activity of the surrounding liver. AHH activity of the early nodules is 10% of the control activity and 33% of the activity in the surrounding nonnodular liver. Nicotinamide adenine dinucleotide phosphate-cytochrome c reductase activity in the microsomes of early nodules is 76% of the control activity and 78% of the activity in the surrounding liver. In the late remodeled nodules, (22 and 25 weeks), the cytochrome P-450 content is 40% of that of controls and AHH activity is 15% of the control activity. In primary hepatomas induced by 2-acetylaminofluorene, cytochrome P-450 content is 21% of that of controls, AHH activity is 11% of the activity of controls, and reductase is 50% of the control activity. These results, indicating a relative nodule deficiency in some of the cellular components believed to be important in the activation of hepatocarcinogens and hepatotoxins, offer one possible explanation for the relative resistance to carcinogen cytotoxicity of hyperplastic liver nodules.

2-Acetylaminofluorene↗
PubMed2025

Partners in root nodule symbiosis respond uniquely to heavy metal stresses in a host genotype-dependent manner.

The mutualistic symbiosis between legume roots and soil rhizobia culminates in the formation of root nodules, where nitrogen is fixed. Root nodule symbiosis is inhibited by heavy metal stress. In this study, we investigated the relative responses of the symbiotic partners to a non-essential heavy metal cadmium (Cd) and an essential heavy metal zinc (Zn) stress and identified patterns in gene expression. We performed dual transcriptomics in nodules, using the Medicago truncatula-Sinorhizobium meliloti symbiotic system. Phenotypes were measured in the wild-type Medicago truncatula and a mutant in an ABC transporter gene (Mtabcg36), which showed compromised nodule formation in control conditions and further after heavy metal treatment. We observed that the rhizobia were particularly sensitive to Zn in mutant nodules. The greatest degree of differential gene expression in the host plant were observed under Cd and Zn treatments in wild-type nodules. Most Cd-regulated host genes were also differentially regulated by Zn, revealing little discernment between an essential and a non-essential ion under increased exposure. Furthermore, the host response to both the stresses affected auxin and iron homeostasis genes in a host genotype-dependent manner. Our results suggested impaired cadmium export from the mutant nodules. These results have potential implications in agricultural management systems and bioremediation strategies.

Symbiosis↗
PubMed1978

Enhancement of the tumorigenicity of preneoplastic mammary nodule lines by enzymatic dissociation.

Preneoplastic mammary nodule lines D1, D2, and C4 were enzymatically dissociated with collagenase, hyaluronidase, and pronase or with only collagenase and hyaluronidase to produce high yields of viable single cells; 10(5) cells were injected into the cleared mammary fat pads of syngeneic BALB/cCrgl mice. In 11 experiments involving three different preneoplastic nodule lines with different tumor potentials, all dissociated nodule cell lines showed a marked increase in tumorigenicity as compared to the same tissues transplanted as 1-mm3 pieces. The results could not be explained on the basis of differences between the amounts of cells transplanted in the two procedures. In a second series of experiments, normal mammary cells from virgin, pregnant, or lactating mice were mixed in different ratios with 10(5) nodule cells and injected into the mammary fat pads. The presence of normal cells reversed the marked increase in the tumorigenicity of enzymatically dissociated nodule cells to a level equal to or less than the tumorigenicity of control transplants (1-mm3 pieces). The growth of 10(5) mammary tumor cells was not inhibited when tumor cells were mixed with 3 x 10(5) normal cells and transplanted into the mammary fat pads. These results showed that enzymatic dissociation can lead to an increase in tumor potential of preneoplastic mammary nodule lines, and they supported the hypothesis that nodule cells, but not neoplastic cells, are sensitive to the growth-inhibitory effects of normal mammary cells.

Adenocarcinoma↗
PubMed1978

An account of pleural effusions, pulmonary nodules and cavities attributable to rheumatoid disease.

Nine case histories and references to published reports are used to illustrate the manifestations and management of pleural effusions, lung nodules and lung cavities which may occur in cases of rheumatoid disease. Repeated aspiration of effusions seldom is useful. They often are chronic and symptomless. What is taking place in some turbid and purulent effusions is debatable, since there can be an associated leucocytosis without infection. In the presence of acute symptoms, such as rigors, careful evaluation of such effusions is required, since there have been fatal examples with rather uncertain bacteriological findings. Lung nodules ordinarily cause a radiographic blemish without symptoms but may predispose to small haemoptyses or may rupture into the pleural cavity to cause a pneumothorax, usually requiring surgical resection of the nodule, whether or not a pleural effusion is present. Some nodules and lung cavities do not have the histology of the typical necrobiotic nodule but it is unlikely that they are fundamentally different. Large cavitated lung lesions which closed on azothioprine treatment are described, together with similar untreated cavities which became secondarily infected with a fatal outcome. It is suggested that the history of possible rheumatoid disease, even of 'aches and pains' must be sought if this aetiology for pleural effusions, lung nodules and unusual lung cavities is not to be overlooked, with the penalty of diagnostic thoracotomy or wrong treatment for the patient.

Adult↗
PubMed1979

Benign rheumatoid nodules.

Nine cases in which subcutaneous rheumatoid nodules were observed in the absence of any evidence of rheumatoid arthritis are recorded. In four of these cases, the nodules appeared during adolescence or adult life, a very rare phenomenon. Synovitis occurred in only one patient, after an interval of 15 years, but it did not persist and other features of rheumatoid arthritis were not present. The siting of the nodules in the sub-cutaneous tissue, the absence of features suggestive of rheumatic fever, necrobiosis lipiodica or fungal infection, and lack of any history of trauma, together with the histological appearance, supported a diagnosis of rheumatoid nodules. In all cases, serological tests for rheumatoid factor were negative but in the only case investigated with immunofluorescent staining, IgG and IgM were demonstrated in the biopsy material. It is important to recognise the fact that these benign nodules do not necessarily indicate that the patient has rheumatoid arthritis, or will develop rheumatoid arthritis in the future. The possible relationship of such nodules to granuloma annulare is discussed.

Adolescent↗
PubMed2026

The Evolutionary Significance of Leaf Nodulation: Evidence from Ardisia and Its Relatives (Primulaceae: Myrsinoideae).

Interactions between plants and microorganisms have long been a central topic in biological research. Bacterial symbiosis on leaf surfaces represents a distinctive and mutually beneficial system within the phyllosphere microbiome. Leaf nodules are the visible manifestation of the symbiosis and confer ecological advantages to host plants by enhancing host resistance against pathogens and herbivores. It has been hypothesized that these advantages promote higher diversification rates in host lineages, but this remains uncertain. Ardisia subg. Crispardisia and its close relatives (Amblyanthopsis and Amblyanthus) within Primulaceae are typical plant groups with leaf nodule symbiosis, making them an ideal system for testing this hypothesis. In this study, we conducted extensive sampling of "Ardisioids" (Ardisia and its allies) and reconstructed their phylogenetic relationships and evolutionary history using plastid genomes and nuclear datasets (i.e., nuclear ribosomal DNA (nrDNA) and genome-wide single nucleotide polymorphisms (SNPs)). We clarified the phylogenetic positions of several "Ardisioids" genera (e.g., Sadiria, Tapeinosperma, Amblyanthus, and Amblyanthopsis) and multiple subgenera within Ardisia. We further detected a rapid radiation during the middle Miocene in Ardisia and its allies. Notably, we found that the leaf-nodulated clade appears to have originated during this period, approximately 11-8 Ma. BAMM (Bayesian Analysis of Macroevolutionary Mixtures) analyses revealed elevated diversification rates in leaf-nodulated lineages, while HiSSE (Hidden State Speciation and Extinction) analyses indicated that leaf nodule symbiosis might have increased speciation rates without significantly affecting extinction rates. These results provide strong evidence that leaf nodule symbiosis, together with other abiotic and biotic factors, represents a key evolutionary innovation that has promoted diversification in Ardisia and its close relatives.

diversification rate↗
PubMed1979

Immunocytochemical localization of epoxide hydrase in hyperplastic nodules induced in rat liver by 2-acetylaminofluorene.

A knowledge of the biological characteristics of carcinogen-induced hyperplastic nodules of rat liver may be important in the understanding of cancer development. Although its biological role remains to be elucidated, the level of microsomal epoxide hydrase (epoxide hydrolase, EC 3.3.2.3) is 5- to 7-fold greater in hyperplastic nodules nodules induced by feeding the hepatocarcinogen 2-acetylaminofluorene than in liver of control rats. After removal of the carcinogen from the diet, the high level of the enzyme is maintained in those nodules that persist and in the hepatocellular carcinomas that subsequently develop. The availability of antibody to the epoxide hydrase made it possible to use electron microscopic immunocytochemistry to localize this enzyme in the cells of hyperplastic nodules. The immunocytochemical procedure provides direct visual evidence for the presence of this enzyme in smooth endoplasmic reticulum and also in rough endoplasmic reticulum (including the nuclear envelope) of the nodule's parenchymal cells.

2-Acetylaminofluorene↗
PubMed1978

Comparison of whole lung tomography and computed tomography for detecting pulmonary nodules.

Detecting pulmonary metastasis is important when planning surgical therapy, radiotherapy, or chemotherapy in patients with known malignancy. A series of 91 patients was studied by both whole lung tomography and computed tomography (CT) of the lungs. More pulmonary nodules were detected with CT than with whole lung tomography in 32 (35%) of the patients. Of the 91 patients in the study, 31 had resection of some or all of the pulmonary nodules. In 27 patients, the nodules were primary or metastatic malignant lesions. Bilateral pulmonary nodules were detected with CT in 13 patients when whole lung tomography had demonstrated nodules in only one lung. CT has replaced whole lung tomography as the method preferred by the authors for detecting pulmonary nodules in selected patients at risk to develop pulmonary metastasis.

Adolescent↗
PubMed1979

Enhancing effect of inducers of liver microsomal enzymes on induction of hyperplastic liver nodules by N-2-fluorenylacetamide in rats.

The effects of inducers of liver microsomal enzymes on the induction of hyperplastic liver nodules by N-2-fluorenylacetamide (2-FAA) were studied in male F344 rats. The rats were fed a diet containing 200 ppm 2-FAA for 2 weeks and then given test chemicals for the following 8 weeks. Partial hepatectomies were performed at the end of the third week of the experiment. The compounds were tested, and their concentrations (in ppm) in the diet were as follows: 1,000 polychlorinated biphenyls (PCB), 500 PCB, 500 PCB plus 70 3-methylcholanthrene (MCA); 500 PCB plus 500 phenobarbital, 70 MCA, 500 phenobarbital, 500 phenobarbital plus 500 beta-naphthoflavone, and 2,500 3-(3,5-dichlorophenyl)-5,5-dimethyloxazoline-dione-2,4 (DDOD). All experimental groups developed significantly greater numbers and total areas of hyperplastic nodules than did the controls. In groups treated similarly with the test chemicals but without partial hepatectomy, the numbers and total areas of hyperplastic nodules were significantly less than those in the experimental groups with partial hepatectomy. Administration of test chemicals except 2-FAA to partially hepatectomized rats did not induce hyperplastic nodules. The present results showed the early detection of the enhancing effect on induction of hyperplastic liver nodules by a system consisting of the following three procedures: 1) 2-FAA feeding; 2) administration of test chemicals, and 3) partial hepatectomy during administration of test chemicals. In this system DDOD enhanced the induction of hyperplastic nodules of the liver.

2-Acetylaminofluorene↗