Majority Of Nodules Research Articles

Ultra low dose CT screen-detected non-malignant incidental findings in the Western Australian Asbestos Review Programme.

Computed tomography (CT)-based studies of asbestos-exposed individuals report a high prevalence of lung cancer, but the utility of low dose CT (LDCT) to screen asbestos-exposed populations is not established. We aimed to describe the prevalence of indeterminate pulmonary nodules and incidental findings on chest LDCT of asbestos-exposed subjects in Western Australia. A total of 906 subjects from the Western Australian Asbestos Review Programme underwent LDCT of the chest as part of regular annual review. An indeterminate (solid) nodule was defined as >50 mm3 and part-solid/non-solid nodules >5 mm. The presence of asbestos-related diseases was recorded with a standardized report. Subjects were mostly (81%) men with a median age of 70 years. Fifty-eight (6.5%) participants were current smokers, 511 (56.4%) ex-smokers and 325 (36.4%) never-smokers. One hundred and four indeterminate nodules were detected in 77 subjects (8.5%); of these, eight cases had confirmed lung cancer (0.88%). Eighty-seven subjects (9.6%) had incidental findings that required further investigation, 42 (4.6%) from lower airways inflammation. The majority of nodules were solid, 4-6 mm and more common with age. Five hundred and eighty (64%) subjects had pleural plaques, and 364 (40.2%) had evidence of interstitial lung disease. The prevalence of LDCT-detected indeterminate lung nodules in 906 individuals with significant asbestos exposure was 8.5%, lower than many other CT studies. Clinically important incidental findings were found in 9.4%, predominantly related to lower respiratory tract inflammation. LDCT appears to effectively describe asbestos-related diseases and is likely to be an acceptable modality to monitor asbestos-exposed individuals.

Evaluation of pulmonary nodules in Asian population.

American College of Chest Physicians (ACCP) provides guidelines to manage pulmonary nodules. Pulmonary nodules however can be malignant or benign. Similar incidence of tuberculosis (TB) and lung cancer in Asian countries raises concern over the relevance of suggested guidelines in Asian population. There is little data on the pattern of clinical practice in the management of pulmonary nodules in Asian country (Singapore). Our study describes the current pattern of clinical practice in this area highlighting the variation in practice and discussing the potential reasons. Retrospective review of the medical records of patients diagnosed with lung cancer in 2010. Sixty nodules were identified in 32 patients. Nodules were detected incidentally on routine imaging in 7 (21.9%) patients. TB contact tracing and pre-employment screening were common ways by which nodules were detected incidentally. Over one third (37.5%) were non-smokers. Majority of nodules were located in the upper lobes of right and left lung followed by right lower lobe (RLL). Only few patients 8 (25%) had positron emission tomography (PET) scan for staging purposes. There were no difference in survival between patients who presented with single, 747 (range, 25-1,840) days vs. multiple nodules 928 (range, 30-2,572) days, P=0.26. In a retrospective analysis of malignancy risk with the probability calculator, 62.5% patients were at low-moderate risk whilst 32.5% were at high risk. The clinical practice of managing pulmonary nodules in Asian population differs from ACCP guidelines. None of the patient had pre-test probability calculated, and few had PET scan. This is because upper lobe predominance of lung cancer is identical to TB, non-smoking history does not have any weight in discounting malignancy risk where many of the Asian lung cancer patients are non-smokers, and the local endemicity of TB and its confounding effect on radiological findings of CT scan and PET scan.

LASER-INDUCED THERMOTHERAPY OF COLLOIDAL CYSTIC THYROID NODULES: THE EFFICACY AND SAFETY

The authors studied the treatment results of application of the laser-induced thermotherapy method in 414 patients with nodular colloid goiter. Dynamics of the nodule sizes was estimated in 298 (72, 0%) patients. Dynamics of thyroid status was assessed in 132 (31, 8%) patients. The average size was reduced more than 60% among the nodules with the volume up to 1 cm³. In case of nodules with the volume more than 8 cm³, the average size was decreased more than 40%. The majority of nodules with the volume of 1 cm³ were reduced more than 50% (45 out of 80), other nodules 19 (23,8%) were decreased more than 75% and 12 nodules completely vanished. The nodules with the volume of 1-2 cm³ were reduced more than half of them on 50% (41 out of 71), the rest of the nodules - on 75% and more than fifth part of them. At the same time, there wasn’t noted the decrease more than 75% in the nodules with the volume of 4 cm ³. However, the volume decrease was observed among such nodules, the majority of the nodules were reduced more than a quarter. During this procedure the patients 305 (73,7%) felt some discomfort and low-intensive pain in area of manipulation. The pains were completely arrested in 289 patients in the end of this procedure, but aching continued in the case of 16 patients for more long time (from 12 to 24 hours). There was noted the temperature rise up to the level of low grade fever in 11 (2,7%) patients during 12-24 hours. Complications of laser-induced thermotherapy had 21 (5,1%) patients. An intracutaneous unstrained haematoma was defined in 15 patients in injection area. There was noted a skin burn in spot of the injection in 5 (1,2%) patients. Paresis of the vocal ligament took place in one patient (0,2%), but it was treated in phonopedist and mobility of the vocal ligament was restored. Hyperthyroidism was caused in two patients and, according to the authors, it could be associated with drug intake of “сordaron”.

Competing Bradyrhizobia strains determine niche occupancy by two native legumes in the Iberian Peninsula

The effect of soil pH on the competitive abilities of two rhizobial strains was investigated in two sterile systems. The two strains come from wild plants of the endemic shrubby legumes Cytisus multiflorus (cmu) and Cytisus balansae (cba). Strains were used to infect seedlings of C. multiflorus, C. balansae, and Ornithopus compressus, grown in soil and hydroponics with acidic and neutral pH. All seedlings were inoculated with a single-strain inoculum containing 106 total cells of one of the two test strains or with a mixed inoculum (1:1 cmu:cba). Controls consisted of non-inoculated seedlings. At harvest, nodule occupants were determined by PCR. The majority of nodules (>95 %) formed on plants grown in acidic soil were occupied by cmu strain. This pattern of nodule occupancy changed in neutral pH both in soil and in hydroponics. When cmu was paired with cba, the former formed 78 % of the nodules in the acidic media and the number of nodules formed by cba was higher in neutral media (8 %). When nodule occupancy was dominated by cmu, the total nitrogen and biologically fixed nitrogen were higher in C. multiflorus and O. compressus. The different nodule occupancy percentages indicate a correlation between the preferred growing conditions of both host plants and Bradyrhizobia strains. Results indicate that soil pH can influence which symbiotype will competitively nodulate C. multiflorus and C. balansae in the field which accounts for the current distribution of these two plants.

Stable Fluorescent and Enzymatic Tagging of Bradyrhizobium diazoefficiens to Analyze Host-Plant Infection and Colonization.

Bradyrhizobium diazoefficiens USDA 110 (formerly named Bradyrhizobium japonicum) can fix dinitrogen when living as an endosymbiont in root nodules of soybean and some other legumes. Formation of a functional symbiosis relies on a defined developmental program mediated by controlled gene expression in both symbiotic partners. In contrast to other well-studied Rhizobium-legume model systems that have been thoroughly examined by means of genetically tagged strains, analysis of B. diazoefficiens host infection has been impaired due to the lack of suitable tagging systems. Here, we describe the construction of B. diazoefficiens strains constitutively expressing single-copy genes for fluorescent proteins (eBFP2, mTurquoise2, GFP+, sYFP2, mCherry, HcRed) and enzymes (GusA, LacZ). For stable inheritance, the constructs were recombined into the chromosome. Effectiveness and versatility of the tagged strains was demonstrated in plant infection assays. (i) The infection process was followed from root-hair attachment to colonization of nodule cells with epifluorescent microscopy. (ii) Monitoring mixed infections with two strains producing different fluorescent proteins allowed rapid analysis of nodule occupancy and revealed that the majority of nodules contained clonal populations. (iii) Microscopic analysis of nodules induced by fluorescent strains provided evidence for host-dependent control of B. diazoefficiens bacteroid morphology in nodules of Aeschynomene afraspera and Arachis hypogaea (peanut), as deduced from their altered morphology compared with bacteroids in soybean nodules.

The Role of CD56 in Thyroid Fine Needle Aspiration Cytology: A Pilot Study Performed on Liquid Based Cytology.

BackgroundFine needle aspiration Cytology (FNAC) fulfills a reliable role in the evaluation of thyroid lesions. Although the majority of nodules are quite easily diagnosed as benign or malignant, 30% of them represent an indeterminate category whereby the application of ancillary techniques (i.e. immunocytochemistry-ICC and molecular testing) has been encouraged. The search for a specific immunomarker of malignancy sheds light on a huge number of ICC stains although none of them attempt to yield 100% conclusive results. Our aim was to define in a pilot study on thyroid FNAC whether CD56 might be a valid marker also in comparison with HBME-1 and Galectin-3.Materials and MethodsInasmuch as this is the largest pilot study using only liquid based cytology (LBC), we selected all the cases only in the categories of benign nodules (BN) and positive for malignancy (PM) for validation purposes. Eighty-five consecutive (including 50 PM and 35 BN) out of 950 thyroid FNACs had surgical follow-up. The ICC panel (HBME-1, Galectin-3 and CD56) was carried out on LBC and histology.ResultsAll BNs and PMs were histological confirmed. CD56 was negative in 96% of the PM while 68.5% of the BNs showed cytoplasmic positivity for this marker, with an overall high sensitivity (96%) but lower specificity (69%). In specific, our 96% of the PMs did not show any follicular cell with CD56 expression. Different ICC combinations were evaluated showing that the panel made up of CD56 plus HBME-1 and Galectin-3 had the highest sensitivity (98%) and specificity (86%).ConclusionsOur pilot study suggests that CD56 may be a good marker for ruling out PTC and its variants. The low specificity suggests that an immunopanel including also HBME-1 and Galectin-3 could obtain the highest diagnostic accuracy in thyroid lesions. Our results suggest that CD56 may be a feasible additional marker for identifying malignancies also in the FNs and SMs.

Thyroid nodules and differentiated thyroid cancer.

The incidence of thyroid nodules and thyroid cancer has increased over the last several decades. This change is influenced by several factors, to include the status of iodine sufficiency, access to the health care system and, perhaps most significantly, the increased use of radiological imaging. Thorough evaluation of a thyroid nodule includes review of the patient's medical and family history, followed by thyroid ultrasound and fine-needle aspiration biopsy. Similar to adults, the majority of nodules in children are benign; however, there is a 3- to 5-fold higher risk that a nodule found in a pediatric patient (≤18 years) will be malignant when compared to an adult. Differentiated thyroid carcinoma (DTC) is the most common malignancy with approximately 90-95% being papillary thyroid carcinoma and the remainder follicular thyroid carcinoma. With proper evaluation and management, the prognosis for pediatric patients with DTC is excellent; however, the risk of treatment complications and recurrence is relatively high. The development of pediatric specific guidelines for the evaluation and management of thyroid nodules and DTC as well as the creation of centers with surgical and medical expertise is crucial in order to optimize care and gain a better understanding of factors that impact disease-specific morbidity.

New Strategies in Diagnosing Cancer in Thyroid Nodules: Impact of Molecular Markers

Thyroid cancer is the most common type of endocrine malignancy, with approximately 55,000 new cases diagnosed in the United States in 2012. However, thyroid nodules are much more prevalent, particularly with increased age, and only a small fraction of those are malignant. Therefore, the major clinical challenge is to reliably differentiate those nodules that are malignant and need to be treated surgically from the majority of nodules that are benign and do not require surgery. The traditional diagnostic approach to this clinical situation is ultrasound-guided fine-needle aspiration (FNA) of the thyroid nodule followed by cytologic examination, which together reliably establish the diagnosis in 70% to 80% of cases. However, in the rest of nodules the presence of cancer cannot be ruled out by FNA cytology, hampering appropriate surgical management and frequently resulting in unnecessary surgical interventions. New approaches to diagnosis of cancer in thyroid nodules are based on mutational and other molecular markers, which can be reliably detected in cells aspirated during the FNA procedure. These markers offer significant improvement in the diagnostic accuracy of FNA cytology and are poised to make a profound effect on the management of patients with thyroid nodules. In addition to the molecular markers that have recently become available for clinical use, rapid development of new sequencing techniques is expected to further improve the accuracy of cancer diagnosis in thyroid nodules and allow for a fully individualized approach to the management of patients with thyroid nodules.

Accuracy of Ultrasound Elastography in the Diagnosis of Thyroid Cancer in a Low-risk Population

Stiffness has been associated to malignancy in prostate and breast, as well as thyroid. Ultrasound elastography objectively measures tissue elasticity, and previous studies have described it as a high sensitivity and specificity technique for the detection of malignant thyroid nodules in high-risk populations. The aim was to assess the accuracy of elastography in a population with low risk of malignancy. 128 consecutive patients with nodular goiter were recruited. Elastography and ultrasound-guided fine-needle aspiration were performed. When malignancy was suspected by citology, surgery was recommended. Thyroid nodules were classified by elastography according the criteria described by Ueno, and an alternative classification. Sensitivity, specificity, predictive values, and odds ratio were calculated. Most patients were female, aged 56.1 year, with single nodule (52.0%) or multinodular goiter (45.6%), and a few thyroiditis (2.4%). The majority of nodules were mostly elastic. Fine-needle aspiration found 86% of benign nodules, 9.3% of indeterminate, and 4.7% possibly malignant. After surgery, 3 malignant nodules were confirmed, all of them being papillary carcinomas. All the malignant nodules were mostly elastic, as well as 75% of indeterminate nodules. Low values of sensitivity and specificity were found for elastic nodules being benign and hard nodules malignant. In a low-risk population for thyroid cancer, elastography lacks accuracy for the diagnosis of malignant nodules.

Cribriform-Morular Variant of Papillary Thyroid Carcinoma: Ultrasonographic and Clinical Characteristics

The cribriform-morular variant of papillary thyroid carcinoma (cmvPTC) is rare. There are few if any studies of the ultrasonographic (US) features of cmvPTC. The aim of this study was to determine the characteristic US and clinical features of the cmvPTC. A retrospective review of the US and clinical features was performed on 18 surgically confirmed cmvPTCs in five patients who were seen at our institution between January 2000 and December 2010. All patients were female with a mean age of 28 years (range, 19-46 years). Two patients presented with palpable lesions, and the other patients were incidentally detected during screening US. On US, the majority of nodules had well-defined, oval to round shapes, and were hypoechoic and solid without calcifications. However, 6 (33.3%) of 18 nodules did have a cystic change. The size of the lesions varied from 0.3 to 3.0 cm (mean, 1.11 cm). None of the nodules were diagnosed as malignant based on the US criteria, but all except one patient had a cytology of their thyroid nodules that was read as malignant, without revealing the subtype of their PTC. Two of the five patients had familial adenomatous polyposis (FAP), and they had bilateral multiple nodules. No metastatic lymph nodes or extrathyroidal extension were identified. To date, none of the patients has had recurrence or metastasis during their mean follow-up of 25 months after thyroidectomy. It appears that most cases of cmvPTC do not have features of malignancy on US and that they are indolent tumors as far as their clinical and histological features are concerned.

Prevalence of unsuspected thyroid nodules in adults on contrast enhanced 16- and 64-MDCT of the chest

To determine the prevalence of unsuspected thyroid nodules on contrast enhanced 16- and 64-modified discrete cosine transform (MDCT) of the chest, in a population of adult outpatients imaged for indications other than thyroid disease. This retrospective study involved review of intravascular contrast-enhanced MDCT scans of the chest from 3077 consecutive adult outpatients, to identify unsuspected thyroid nodules. Exclusion criteria included history of thyroid cancer, known thyroid nodules or thyroid disease and risk factors for thyroid cancer, as evidenced by their medical records. One of 9 radiologists recorded number of nodules, location and bidirectional measurement of largest nodule, as well as amount of thyroid visualized on the chest computed tomography (CT). Presence of nodule was correlated with age, gender, race and percentage of thyroid imaged. A total of 2510 (2510/3077 or 81.6%) study subjects were included in the data analysis; among them, one or more nodules were identified in 629 subjects (629/2510 or 25.1%), with 242 (242/629 or 38.5%) having multiple nodules. Patients with nodule(s) were significantly older than those without (64 ± 13 years vs 58 ± 14 years, P < 0.0001), and female gender was associated with presence of nodule(s) (373/1222 or 30.5% vs 256/1288 or 19.9%, P < 0.0001). Women were also more likely having multiple nodules (167/373 or 44.8%) compared to men (75/256 or 29.3%, P < 0.0001). The majority of nodules (427/629 or 67.9%) were less than 1 cm. This retrospective review revealed a prevalence of 25.1% for unsuspected thyroid nodules on contrast-enhanced chest CT.

A re-appraisal of the biology and terminology describing rhizobial strain success in nodule occupancy of legumes in agriculture

Aim: To ensure that the majority of nodules on a legume are occupied by the inoculant strain poses a significant challenge to maximising nitrogen fixation in agricultural settings. The aim of this review is to establish a set of common terms with which to classify and interrogate experiments that investigate nodule occupancy in legumes. Results: At least six different terminologies have been developed to discuss experimental outcomes where legumes have access to more than one rhizobial strain. In this review we nominate a set of preferred terms: promiscuous, exclusive, selective and non-selective nodulation in an attempt to provide conformity to the general scientific pursuit of understanding the circumstances leading to nodule occupancy in legumes when more than one strain has the opportunity to form the nodule. Discussion: To maximise nitrogen fixation from legumes, a primary challenge is to prevent rhizobia resident in the soil from dominating nodule occupation, since whilst they may be numerically dominant, they are often not optimally matched for nitrogen fixation with the introduced legume. It is apparent, however, that at times the legume host is able to preferentially enter into symbiosis with a fully effective strain, even if an ineffective strain is present and numerically dominant. Conclusion: This manuscript reviews the terminology currently applied to nodulation outcomes in introduced legume symbioses where more than one strain type is available to infect the plant. We suggest adoption of a more stringent terminology as the research discipline matures to exploit genome sequence information. We have suggested the term "selective nodulation" to describe certain nodulation outcomes that are not based upon numerical supremacy.

Supplementation of selenium reduces chemical hepatocarcinogenesis in male Sprague-Dawley rats

Selenium is an essential micronutrient mineral found mainly in soils and has been shown to prevent certain cancers in humans and animals. However, the dose and effects of selenium on liver cancer are controversial. The aim of this study was to investigate the effects of sodium selenite (4 mg/kg in drinking water) on chemically induced hepatocarcinogenesis in rats. Hepatocarcinogenesis was induced by a single intraperitoneal injection of diethyl nitrosamine (DEN) (200 mg/kg body weight) and 2 weeks later, the carcinogenic effect was promoted by 2-acetylaminofluorene (2-AAF) (0.02%). 44 Sprague-Dawley rats were divided into 6 groups: negative control, positive control (DEN+2-AAF), pre-selenium group (sodium selenite for 4 weeks, then DEN+2-AAF), pre-selenium control group (sodium selenite for 4 weeks, no DEN or 2-AAF), post-selenium group (sodium selenite for 8 weeks after 4 weeks of DEN injection) and post-selenium control group (sodium selenite for 8 weeks, no DEN or 2-AAF). Hematoxylin and eosin plus Gordon and Sweet’s methods were used to stain liver tissues. The results showed that the number and sizes of hepatic nodules in pre- and post-selenium treatment groups significantly decreased ( P<0.05) compared with the positive control. Microscopic analysis of pre- and post-selenium groups showed that the majority of nodules were hyperplastic with preserved liver architecture, whereas the positive control was full of neoplastic nodules with a completely disrupted liver architecture. Hence, pre- and post-selenium treatments can reduce the extent of liver cancer on chemically induced hepatocarcinogenesis in rats.

Different T cell subsets in the nodule and synovial membrane: Absence of interleukin‐17A in rheumatoid nodules

To determine gene expression of the interleukin-17 (IL-17) family members (IL-17A-F) in rheumatoid subcutaneous nodules, and to assess the cytokines involved in regulating IL-17A expression. Total RNA was isolated from 19 nodules obtained from 16 different patients with rheumatoid arthritis (RA). Reverse transcription-polymerase chain reaction (PCR) was used to screen for gene expression of the IL-17 subtypes (IL-17A-F) in all nodules. Quantitative real-time PCR was used to measure the expression of interferon-gamma (IFN gamma), IL-6, IL-23, IL-12, and transforming growth factor beta (TGFbeta), relative to GAPDH as control, in a subset of 10 nodules. IL-17A gene expression was present in only 1 of 19 nodules, IL-17B in 17 of 19 nodules, IL-17C in 18 of 19 nodules, IL-17D in 16 of 19 nodules, and IL-17E in 3 of 19 nodules. IL-17F was absent in all samples. Cytokines that stimulate IL-17A production (IL-6, IL-23) as well as those that inhibit IL-17A production (IL-12, IFN gamma, TGFbeta) were present in the majority of nodules. Quantitative real-time PCR showed a similar pattern of gene expression for the individual cytokines between the different nodules. The mean +/- SD expression of IL-6 relative to GAPDH was 2.28 +/- 2.2 ng, and that of TGFbeta was 2.96 +/- 1.14 ng. There was a lower relative expression of IL-23 (0.05 +/- 0.05 ng), while the expression of IFN gamma was 0.67 +/- 0.68 ng and that of IL-12 was 0.48 +/- 0.23 ng. IL-17 family members are varyingly expressed in rheumatoid nodules. The paucity of IL-17A in nodules suggests an important difference from that observed in the synovium. The expression of IL-23 below a critical threshold level seems the most likely explanation for the virtual absence of IL-17A. The presence of tissue destruction within the nodule despite the absence of IL-17A suggests that IL-17A may be an important amplifier rather than an absolute requirement for inflammation in RA.

Effects of single and dual inoculation with selected microsymbionts (rhizobia and arbuscular mycorrhizal fungi) on field growth and nitrogen fixation of Calliandra calothyrsus Meissn

Our study aimed to assess the effect of dual inoculation with the selected Rhizobium strain KWN35 and the arbuscular mycorrhizal isolate BEG 176 (Glomus etunicatum) on the growth of Calliandracalothyrsus cultivated under irrigation in the field in Senegal (Dakar) over a period of 24 months. Although plants inoculated with both microsymbionts grew better (height and root collar diameter) than plants from three other inoculation treatments (control, single inoculation with KWN35 or BEG 176), these results were not statistically different except at 1 and 5 months after field transplantation. KWN35 was present in a relatively high percentage of nodules harvested from plants inoculated with this rhizobial strain either alone or with mycorrhiza (approximately 60% and 40% 1 and 2 years after field transplantation respectively). The percentage of mycorrhizal root infections was around 60% in the inoculated plants after 12 months with significantly higher N, P and K foliar contents of trees compared with the non-inoculated controls. However, as for nodulation, by 24 months after transplantation, there were no significant differences between treatments. We conclude that field inoculation of C. calothyrsus with Rhizobium strain KWN35 and arbuscular mycorrhizal isolate BEG 176 did not have a long-lasting effect on the growth of trees, even when a majority of nodules were occupied by the inoculated rhizobia and the roots infected by the mycorrhiza. Several reasons can be postulated for these results, such as a possible effect of soil fertility on the efficiency of the nodules.

Immunohistochemical staining for thyroid peroxidase (TPO) of needle core biopsies in the diagnosis of scintigraphically cold thyroid nodules

BackgroundCold thyroid nodules are common, in particular in iodine-deficient areas, but only a minority of them are malignant requiring surgery. Thyroid peroxidase (TPO) immunostaining of fine-needle aspiration cytology (FNAC) material has proven helpful in diagnosing cells from malignant lesions, but the procedure has its limitations in a routine setting.PurposeTo improve diagnosis and reduce surgery rate, the FNAC procedure was replaced by needle core biopsy (NCB), which was routinely stained for TPO by the monoclonal antibody mAb 47.Materials and methodsDuring a 5-year period 427 consecutive patients with a cold thyroid nodule were evaluated by ultrasound-guided NCB, which had been routinely stained for TPO in an automated immunostainer. Sensitivity and specificity and predictive values of the TPO immunostaining were estimated, based on the final diagnosis obtained from surgical resection.ResultsThe majority of nodules with benign NCB diagnosis were not surgically removed, and thus a subgroup of 140 operated nodules formed the basis for the calculations. Sensitivity and specificity for benign and malignant lesions were 100% if the oxyphilic variant of adenomas and minimally invasive follicular carcinomas were excluded. By inclusion of these, the values fell to 89% and 97%, respectively. The predictive value of a positive test was 96% and the predictive value of a negative test was 97%.ConclusionTPO immunostaining was found to be a valuable adjunct to morphology in the diagnosis of cold thyroid nodules of the nonoxyphilic type.

Leghaemoglobin oxygenation gradients in alfalfa and yellow sweetclover nodules.

Respiration in support of N(2) fixation by rhizobia in legume root nodules depends on an adequate supply of O(2), but excessive O(2) can damage nitrogenase, the key enzyme. The movement of O(2) into and within the nodule is driven by gradients in the concentration of O(2) or in the oxygenation of the O(2)-carrier, leghaemoglobin. Steeper gradients may increase flux to the sites of respiration, but gradients also raise the possibility of inadequate O(2) in some nodule zones and excessive O(2) in others. No detailed study of O(2) gradients in the interior of nodules has been published previously. Spectral changes in leghaemoglobin with oxygenation, previously used to measure the average O(2) status of the nodule interior, were used to map longitudinal gradients in O(2) and in respiratory capacity in the elongated nodules of alfalfa (Medicago sativa L.) and sweetclover (Melilotus officinalis L.). Variability among nodules under air in the magnitude and direction of internal O(2) gradients was seen in both species. Despite consistently higher respiratory capacity near the meristematic tip, a majority of nodules had higher O(2) towards the tip than towards the base. These results contrast with a previous report, apparently based on limited data, but they are consistent with anatomical and tracer studies showing higher gas permeability near the tip.

Breast ultrasound and new technologies

Technological advances are opening new fields of investigation for breast ultrasound. Specificity and color Doppler, staging and extended clinical roles in benign conditions are reviewed according to the state-of-the-art technology. Annular arrays are the best technical choice but new broadband linear arrays approach their quality and allow to visualize very slow flows within the breast. Still limitations exist and ultrasound is not suitable for screening. Providing better definition of normal as well as abnormal features, high-resolution sonography improves the specificity of the diagnosis for the majority of nodules and allows a better definition of both local and regional staging in nodular and diffuse conditions. Color Doppler and contrast media are increasing ultrasound specificity and are particularly useful in evaluating vascularity during therapies. Impressive results are achieved in the study of multifocal and multicentric carcinomas, in determining the degree of tumoral invasion of the surrounding tissues and of the ducts. Local and regional staging are greatly improved; the information given to the surgeon is more precise and allows easier therapeutic decisions. The diagnostic role of high-frequency ultrasound is also convincing in most benign conditions like inflammations, traumas and duct ectasia. In most of these conditions sonography is the best imaging modality to study the disease type and extent. The ability to monitor treatment efficacy or the natural outcome makes ultrasound and color Doppler a gold standard for breast inflammations.

Effect of pH on competition for nodule occupancy by type I and type II strains ofRhizobium leguminosarum bv.phaseoli

The effect of soil pH on the competitive abilities of twoRhizobium leuminosarum bv.phaseoli type I and one type II strains was examined in a nonsterile soil system.Phaseolus vulgaris seedlings, grown in unlimed (pH 5.2) or limed (pH 7.6) soil, were inoculated with a single-strain inoculum containing 1 × 106 cells mL−1 of one of the three test strains or with a mixed inoculum (1:1, type I vs. type II) containing the type II strain CIAT 899 plus one type I strain (TAL 182 or CIAT 895). At harvest, nodule occupants were determined. In a separate experiment, a mixed suspension (1:1, type I vs. type II) of CIAT 899 paired with either TAL 182 or CIAT 895 was used to inoculateP. vulgaris seedlings grown in sterile, limed or unlimed soil. The numbers of each strain in the rhizosphere were monitored for 10 days following inoculation. The majority of nodules (> 60%) formed on plants grown in acidic soil were occupied by CIAT 899, the type II strain. This pattern of nodule occupancy changed in limed soil. When CIAT 899 was paired with TAL 182, the type I strain formed 78% of the nodules. The number of nodules formed by CIAT 899 and CIAT 895 (56% and 44%, respectively) were not significantly different. The observed patterns of nodule occupancy were not related to the relative numbers or specific growth rates of competing strains in the host rhizosphere prior to nodulation. The results indicate that soil pH can influence which symbiotype ofR. leguminosarum bv.phaseoli will competitively nodulateP. vulgaris.

Assessment of faba bean (Vicia faba) response to inoculation with Rhizobium leguminosarum in clay loam Nile Delta soil

A field experiment was conducted to assess the response to inoculation with rhizobia in a clay loam soil of the Nile Delta using faba bean (Vicia faba) for two successive winter seasons (1985/6 and 1986/7). Three selected strains of Rhizobium leguminosarum, TAL 634, NRC 65 and TAL 1400, were used singly or in combination as peat-based inocula in 1985/6 winter season. Strain TAL 1400 was replaced by strain F9 in the 1986/7 winter season. A significant seed yield response was obtained only with strain TAL 1400, in the 1985/6 season. In the 1986/7 season, no significant yield response was observed with any of the strains. The serotyping of nodules collected in the 1985/6 season showed that strain TAL 1400 was more competitive than either the indigenous rhizobia or the two inoculant strains. However, the majority of nodules formed in the 1986/7 season were formed from strains other than the inoculant ones.