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Laurent?Michaud Frédéric?Coutenier Guillaume?Podevin Arnaud?Bonnard Fran?ois?Becmeur Naziha?Khen-Dunlop Frédéric?Auber Aude?Maurel Thomas?Gelas Martine?Dassonville Corinne?Borderon Alain?Dabadie Dominique?Weil Christian?Piolat Anne?Breton Djamal?Djeddi Alain?Morali Florence?Bastiani Thierry?Lamireau Frédéric?Gottrand
Background
Congenital esophageal stenosis (CES) is a rare condition frequently associated with esophageal atresia (EA). There are limited data from small series about the presentation, treatment, and outcomes of CES.Methods
Medical records of all patients with CES included in the French Network on Esophageal Malformations and Congenital Diseases were reviewed retrospectively with regard to diagnosis, treatment, and outcome.Results
Over 18 years, 61 patients (30 boys) had CES, and 29 (47%) of these patients also had EA. The mean age at diagnosis was 24 months (1 day to 14 years) and was younger in patients with CES and EA than in those with isolated CES (7 vs. 126 months, p?<?0.05). Twenty-one of the 61 patients with CES had no clinical symptoms: in three patients, the findings were incidental, and in 18 of the 29 patients with associated EA, CES was diagnosed at the time of surgical repair of EA or during a postoperative systematic esophageal barium study. In the 40 other patients, at diagnosis, 50% presented with dysphasia, 40% with vomiting, 50% with food impaction, and 42% with respiratory symptoms. Diagnosis of CES was confirmed by esophageal barium study (56/61) and/or esophageal endoscopy (50/61). Sixteen patients had tracheobronchial remnants (TBR), 40 had fibromuscular stenosis (FMS), and five had membrane stenosis (MS). Thirty-four patients (56%) were treated by dilation only (13/34 remained asymptomatic at follow-up); 15 patients were treated by dilation but required later surgery because of failure (4/15 remained asymptomatic at follow-up); and nine patients had a primary surgical intervention (4/9 were asymptomatic at follow-up). Dilation was complicated by esophageal perforation in two patients (3.4%). At follow-up, dysphagia remained in 36% (21/58) of patients, but the incidence did not differ between the EA and the isolated CS groups (10/29 vs. 7/32, p?=?0.27).Conclusions
CS diagnosis can be delayed when associated with EA. Dilation may be effective for treating patients with FMS and MS, but surgical repair is often required for those with TBR. Our results show clearly that, regardless of the therapeutic option, dysphagia occurs frequently, and patients with CES should be followed over the long term.3.
Dorothy A Sparks Daniel M Chase Mark Forsyth Gregg Bogen Jon Arnott 《Journal of medical case reports》2010,4(1):1-3
Introduction
Craniosynostosis can affect the skull in various ways. The most common forms are abnormal skull shape and beaten copper pattern, while Lückenschädel (or lacunar skull) is one of the least common forms.Case presentation
We report the case of a 3-month-old Caucasian boy with multiple suture craniosynostosis and with acquired craniomeningocele presenting as a bulging mass in the lateral occipital area.Conclusion
To the best of our knowledge, this is the first report of a patient with multiple suture craniosynostosis and acquired craniomeningocele. 相似文献4.
Hideki Kimura Toshihiko Iizasa Aki Ishikawa Mitsuru Yoshino Masato Shingyouji Masaki Kimura Tetushi Hirata Akiko Odaka Keiko Matsubayasi 《Journal of medical case reports》2008,2(1):1-7
Introduction
Dynamic retinal vessel analysis represents a well-established method for the assessment of vascular reactivity during both normal conditions and after various provocations. We present a case where the subject showed abnormal retinal vessel reactivity after fasting voluntarily for 20 hours.Case presentation
A healthy, 21-year-old man who fasted voluntarily for 20 hours exhibited abnormal retinal vascular reactivity (dilation and constriction) after flicker provocation as measured using the Dynamic Retinal Vessel Analyser (Imedos, Jena, Germany).Conclusion
The abnormal vascular reactivity induced by fasting was significant; abnormal levels of important nutrients due to fasting and dehydration could play a role through altering the concentration of vasoactive substances such as nitric oxide. This hypothesis needs further investigation. 相似文献5.
Background
Although cardiac auscultation remains important to detect abnormal sounds and murmurs indicative of cardiac pathology, the application of electronic methods remains seldom used in everyday clinical practice. In this report we provide preliminary data showing how the phonocardiogram can be analyzed using color spectrographic techniques and discuss how such information may be of future value for noninvasive cardiac monitoring.Methods
We digitally recorded the phonocardiogram using a high-speed USB interface and the program Gold Wave http://www.goldwave.com in 55 infants and adults with cardiac structural disease as well as from normal individuals and individuals with innocent murmurs. Color spectrographic analysis of the signal was performed using Spectrogram (Version 16) as a well as custom MATLAB code.Results
Our preliminary data is presented as a series of seven cases.Conclusions
We expect the application of spectrographic techniques to phonocardiography to grow substantially as ongoing research demonstrates its utility in various clinical settings. Our evaluation of a simple, low-cost phonocardiographic recording and analysis system to assist in determining the characteristic features of heart murmurs shows promise in helping distinguish innocent systolic murmurs from pathological murmurs in children and is expected to useful in other clinical settings as well. 相似文献6.
Susan Sparks Goran Rakocevic Galen Joe Irini Manoli Joseph Shrader Michael Harris-Love Barbara Sonies Carla Ciccone Heidi Dorward Donna Krasnewich Marjan Huizing Marinos C Dalakas William A Gahl 《BMC neurology》2007,7(1):1-13
Background
Hereditary Inclusion Body Myopathy (HIBM) is an autosomal recessive, adult onset, non-inflammatory neuromuscular disorder with no effective treatment. The causative gene, GNE, codes for UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase, which catalyzes the first two reactions in the synthesis of sialic acid. Reduced sialylation of muscle glycoproteins, such as α-dystroglycan and neural cell adhesion molecule (NCAM), has been reported in HIBM.Methods
We treated 4 HIBM patients with intravenous immune globulin (IVIG), in order to provide sialic acid, because IgG contains 8 μmol of sialic acid/g. IVIG was infused as a loading dose of 1 g/kg on two consecutive days followed by 3 doses of 400 mg/kg at weekly intervals.Results
For all four patients, mean quadriceps strength improved from 19.0 kg at baseline to 23.2 kg (+22%) directly after IVIG loading to 25.6 kg (+35%) at the end of the study. Mean shoulder strength improved from 4.1 kg at baseline to 5.9 kg (+44%) directly after IVIG loading to 6.0 kg (+46%) at the end of the study. The composite improvement for 8 other muscle groups was 5% after the initial loading and 19% by the end of the study. Esophageal motility and lingual strength improved in the patients with abnormal barium swallows. Objective measures of functional improvement gave variable results, but the patients experienced improvements in daily activities that they considered clinically significant. Immunohistochemical staining and immunoblotting of muscle biopsies for α-dystroglycan and NCAM did not provide consistent evidence for increased sialylation after IVIG treatment. Side effects were limited to transient headaches and vomiting.Conclusion
The mild benefits in muscle strength experienced by HIBM patients after IVIG treatment may be related to the provision of sialic acid supplied by IVIG. Other sources of sialic acid are being explored as treatment options for HIBM. 相似文献7.
Carlos Cotrim Maria J Loureiro Rita Miranda Sofia Almeida Ana R Almeida Otília Simões Pedro Cordeiro Manuel Carrageta 《Cardiovascular ultrasound》2007,5(1):1-3
Background
The occurrence of pulmonary artery obstruction in the course of acute aortic dissection is an unusual complication. The mechanism implicated is the rupture of the outer layer of the aorta and the subsequent hemorrhage into the adventitia of the pulmonary artery that causes its wall thickening and, at times, produces extrinsic obstruction of the vessel. There are no reports of this complication in acute intramural hematoma.Case presentation
An 87-year-old woman was admitted to the hospital in shock after having had severe chest pain followed by syncope. An urgent transesophageal echocardiogram revealed the presence of acute intramural hematoma, no evidence of aortic dissection, severe pericardial effusion with cardiac tamponade, and periaortic hematoma that involved the pulmonary artery generating circumferential wall thickening of its trunk and right branch with no evidence of flow obstruction. Urgent surgery was performed but the patient died in the operating room. The post mortem examination, in the operating room, confirmed that there was an extensive hematoma around the aorta and beneath the adventitial layer of the pulmonary artery, with no evidence of flow obstruction.Conclusion
This is the first time that this rare complication is reported in the scenario of acute intramural hematoma and with the transesophageal echocardiogram as the diagnostic tool. 相似文献8.
Purpose
The authors present a clinical report of a perforate syringocele diagnosed in a male patient and they review the clinical, radiological and therapeutic aspects of this disease.Case report
A 50-year-old man attended the emergency room with perineal abscess. Computerized Tomography (CT) scan was used to establish the diagnosis. This patient also underwent urethrocystoscopy, sonography and retrograde urethrography.Results
Treatment consisted of open surgical evacuation of the perineal abscess with bladder catheter. Urethrocystoscopy showed a large perforate syringocele in the urethra with no need for endoscopy marsupialization. No recurrence was observed at follow-up at 3 months.Conclusion
Syringocele is a rare malformation which usually is asymptomatic. It can be congenital or acquired and can be classified into four morphological types. The most frequent treatment is endoscopic marsupialization of the syringocèle. Open surgical excision is recommended for complicated syringocèle with abscess or perineal pain. 相似文献9.
Abel A Nathan Viswanathan Mohan Subash S Babu Soumi Bairagi Madhulika Dixit 《BMC endocrine disorders》2011,11(1):1-8
Background
Patients with acute myocardial infarction and newly detected abnormal glucose regulation have been shown to have a less favourable prognosis compared to patients with normal glucose regulation. The importance and timing of oral glucose tolerance testing (OGTT) in patients with acute myocardial infarction without known diabetes is uncertain. The aim of the present study was to evaluate the impact of abnormal glucose regulation classified by an OGTT in-hospital and at three-month follow-up on clinical outcome in patients with acute ST elevation myocardial infarction (STEMI) without known diabetes.Methods
Patients (n = 224, age 58 years) with a primary percutanous coronary intervention (PCI) treated STEMI were followed for clinical events (all-cause mortality, non-fatal myocardial re-infarction, recurrent ischemia causing hospital admission, and stroke). The patients were classified by a standardised 75 g OGTT at two time points, first, at a median time of 16.5 hours after hospital admission, then at three-month follow-up. Based on the OGTT results, the patients were categorised according to the WHO criteria and the term abnormal glucose regulation was defined as the sum of impaired fasting glucose, impaired glucose tolerance and type 2-diabetes.Results
The number of patients diagnosed with abnormal glucose regulation in-hospital and at three-month was 105 (47%) and 50 (25%), respectively. During the follow up time of (median) 33 (27, 39) months, 58 (25.9%) patients experienced a new clinical event. There were six deaths, 15 non-fatal re-infarction, 33 recurrent ischemia, and four strokes. Kaplan-Meier analysis of survival free of composite end-points showed similar results in patients with abnormal and normal glucose regulation, both when classified in-hospital (p = 0.4) and re-classified three months later (p = 0.3).Conclusions
Patients with a primary PCI treated STEMI, without previously known diabetes, appear to have an excellent long-term prognosis, independent of the glucometabolic state classified by an OGTT in-hospital or at three-month follow-up.Trial registration
The trial is registered at http://www.clinicaltrials.gov, NCT00926133. 相似文献10.
Jan Čermák Pavel Cudlín Roman Gebauer Isabella Børja Milena Martinková Zdeněk Stanĕk Jan Koller Jindřich Neruda Nadezhda Nadezhdina 《Plant and Soil》2013,372(1-2):401-415
Aims
Estimates of root absorption magnitude are needed for the balanced management of forest ecosystems, but no methods able to work on the whole tree and stand level were available. Modified earth impedance method was developed recently and here it was tested, by comparing the results with those obtained by combination of several classical methods.Methods
We used direct (soil cores, scanning and microscopy) and indirect (sap flow patterns and modified earth impedance) methods in an attempt to estimate the absorptive root area indexes (RAI) at two sites of about 25 and 40-years-old Norway spruce. We considered the geometric surfaces of all scanned fine roots to be equal to the fine root absorptive area (RAI scan ). To estimate the potentially physically permeable area of fine roots, we microscopically evaluated the point of secondary xylem appearance and calculated the geometric area of root portions with primary structure (RAI micro ). We termed the area of electrically conductive root surface as the active (ion) absorptive area (RAI mei ) and measured its extent by the modified earth impedance (MEI) method.Results
The highest values for absorptive root areas at the two experimental sites we obtained with the scanning method (RAI scan was considered to be 100%), followed by the RAI micro (51%) and RAI mei (32%). RAImei reached about 2/3 of RAImicro. The surface area of the ectomycorrhizal hyphae was an order of magnitude larger than that of all fine roots, but the MEI did not measure such increase.Conclusions
We showed that the absorptive root area, indirectly estimated by the MEI, provides consistent results that approach the values obtained for fine roots with a primary structure estimated by traditional direct methods. The similar range of the values for the absorptive root surface area obtained by microscopy and by the MEI method indicates that this method is feasible and that it could be used to determine the extent of active absorptive root surface areas in forests. 相似文献11.
Root growth in biopores—evaluation with in situ endoscopy 总被引:1,自引:0,他引:1
Background and aims
The significance of biopores for nutrient acquisition from the subsoil depends on root-soil contact, which in turn is influenced by root architecture. The aim of this study was to detect differences regarding the architecture and root-soil contact of homorhizous barley roots (Hordeum vulgare L.) and allorhizous oilseed rape roots (Brassica napus L.) growing in biopores.Methods
In situ endoscopy was used as a technique that allows non-destructive display of pore wall characteristics and root morphology inside large biopores under field conditions.Results
For both crops, about 85 % of all roots did establish contact to the pore wall. However, according to their different root architecture, the two crops varied in their strategy of resource acquisition: While barley was characterized by thin vertical or ingrowing roots, most of them in direct contact to the pore wall, oilseed rape established contact to the pore wall predominantly via lateral roots.Conclusions
Root morphological and pore wall assessment with in situ endoscopy in combination with detailed studies of soil biochemical and soil physical parameters of the pore wall is considered an essential prerequisite for more precise future modelling of nutrient acquisition and uptake. 相似文献12.
Background
We previously developed the DBRF-MEGN (difference-based regulation finding-minimum equivalent gene network) method, which deduces the most parsimonious signed directed graphs (SDGs) consistent with expression profiles of single-gene deletion mutants. However, until the present study, we have not presented the details of the method's algorithm or a proof of the algorithm.Results
We describe in detail the algorithm of the DBRF-MEGN method and prove that the algorithm deduces all of the exact solutions of the most parsimonious SDGs consistent with expression profiles of gene deletion mutants.Conclusions
The DBRF-MEGN method provides all of the exact solutions of the most parsimonious SDGs consistent with expression profiles of gene deletion mutants. 相似文献13.
Hichem Jallouli Hammadi Fakhfakh Nouri Rebai Issam Ben Abdallah Mohammed Trifa Ali Bahloul Mohamed Nabil Mhiri 《Andrologie》2007,17(3):230-235
Introduction
Undescended testis is a frequent congenital disease, more often diagnosed and treated during childhood. However, due to ignorance or negligence, this disease can be seen even after puberty, when it raises a therapeutic problem: is orchidopexy still useful? This study was designed to evaluate the outcome of orchidopexy at adulthood in terms of improvement of fertility and prevention of malignant degeneration.Material and methods
Retrospective study performed over a 23-year period (1983–2005). We have found 259 patients with undescended testis diagnosed and treated after the age of 18 years.Results
The mean age of patients was 24 years (range: 18–63). In the majority of cases, undescended testis was diagnosed at a systemic medical examination in 199 patients (77% of cases), and in a context of infertility in 33 patients, testicular malignancy in 8 patients, testicular torsion in 2 patients and, in 17 cases, undescended testis had been known since birth but was neglected by the parents. Undescended testis was unilateral in 209 cases and bilateral in 50 cases. Out of 37 couples, only 4 gave birth to children (10.8% paternity rate). Sperm analysis was abnormal in all infertile patients. All patients were treated by orchidopexy, except for 36 patients in whom orchidectomy was performed due to testicular atrophy (27 cases), malignancy (8 cases) or necrosis (1 case). Biopsy of the intrascrotal testis was performed in 3 patients with unilateral cryptorchidism. Histological examination was normal in two cases and abnormal in one case. The long-term outcome was characterized by:- Testicular atrophy in 6 patients (2.7% of cases).
- Progression to malignancy in 3 patients (1.3% of cases).
- Improvement of sperm parameters in 16 of 33 infertile patients (48.5%); 4 patients fathered children after treatment.
Conclusion
Orchidopexy at adulthood can lead to improvement of infertility. It can also decrease the incidence of malignancy and facilitate clinical examination looking for possible malignancy. However, the best treatment remains preventive, based on early diagnosis and orchidopexy. 相似文献14.
Nadia G Elhefnawy 《Diagnostic pathology》2011,6(1):1-3
Background
Special stains, such as reticulin stain and CD34 immunostain, are very helpful in the diagnosis of well differentiated hepatocellular carcinoma (HCC). Most studies have shown that absent or decreased reticulin stain or an abnormal reticulin pattern with widened trabeculae is reliable for the diagnosis of well-differentiated HCC.Case report
We report here two cases of well differentiated HCC with an unusual reticulin staining pattern. A strongly positive reticulin network was preserved within the tumor, which surrounded individual tumor cells in a monolayered trabecular pattern. At the same time, an increased CD34 stain was present in the tumor.Conclusions
This unusual reticulin pattern represents part of the diverse reticulin staining patterns seen in HCC. Although this staining pattern is rare, it should be recognized when diagnosing well-differentiated HCC in small samples such as cellblock of fine needle aspiration or small core biopsies. 相似文献15.
Shujun Li Zhigang Li Fengjie Guo Xuebo Qin Bin Liu Zhe Lei Zuoqing Song Liya Sun Hong-Tao Zhang Jiacong You Qinghua Zhou 《Journal of biomedical science》2011,18(1):1-9
Background
Artemin (ARTN) is a neurotrophic factor belonging to the glial cell-derived neurotrophic factor family of ligands. To develop potential therapy targeting ARTN, we studied the roles of miR-223 in the migration and invasion of human esophageal carcinoma.Methods
ARTN expression levels were detected in esophageal carcinoma cell lines KYSE-150, KYSE-510, EC-9706, TE13, esophageal cancer tissues and paired non-cancerous tissues by Western blot. Artemin siRNA expression vectors were constructed to knockdown of artemin expression mitigated migration and invasiveness in KYSE150 cells. Monolayer wound healing assay and Transwell invasion assay were applied to observe cancer cell migration and invasion. The relative levels of expression were quantified by real-time quantitative PCR.Results
ARTN expression levels were higher in esophageal carcinoma tissue than in the adjacent tissue and was differentially expressed in various esophageal carcinoma cell lines. ARTN mRNA contains a binding site for miR-223 in the 3'UTR. Co-transfection of a mir-223 expression vector with pMIR-ARTN led to the reduced activity of luciferase in a dual-luciferase reporter gene assay, suggesting that ARTN is a target gene of miR-223. Overexpression of miR-223 decreased expression of ARTN in KYSE150 cells while silencing miR-223 increased expression of ARTN in EC9706 cells. Furthermore, overexpression of miR-223 in KYSE150 cells decreased cell migration and invasion. Silencing of miR-223 in EC9706 cells increased cell migration and invasiveness.Conclusions
These results reveal that ARTN, a known tumor metastasis-related gene, is a direct target of miR-223 and that miR-223 may have a tumor suppressor function in esophageal carcinoma and could be used in anticancer therapies. 相似文献16.
Mary LaLonde Hilde Janssens Suyong Yun Juan Crosby Olga Redina Virginie Olive Yelena M Altshuller Seok-Yong Choi Guangwei Du Peter J Gergen Michael A Frohman 《BMC developmental biology》2006,6(1):1-13
Background
Cellularization of the Drosophila embryo is an unusually synchronous form of cytokinesis in which polarized membrane extension proceeds in part through incorporation of new membrane via fusion of apically-translocated Golgi-derived vesicles.Results
We describe here involvement of the signaling enzyme Phospholipase D (Pld) in regulation of this developmental step. Functional analysis using gene targeting revealed that cellularization is hindered by the loss of Pld, resulting frequently in early embryonic developmental arrest. Mechanistically, chronic Pld deficiency causes abnormal Golgi structure and secretory vesicle trafficking.Conclusion
Our results suggest that Pld functions to promote trafficking of Golgi-derived fusion-competent vesicles during cellularization. 相似文献17.
Edith Fleischmann Corinna Marschalek Katja Schlemitz Jarrod E Dalton Thomas Gruenberger Friedrich Herbst Andrea Kurz Daniel I Sessler 《BMC anesthesiology》2009,9(1):1-9
Background
Even the best cancer surgery is usually associated with minimal residual disease. Whether these remaining malignant cells develop into clinical recurrence is at least partially determined by adequacy of host defense, especially natural killer cell function. Anesthetics impair immune defenses to varying degrees, but nitrous oxide appears to be especially problematic. We therefore tested the hypothesis that colorectal-cancer recurrence risk is augmented by nitrous oxide administration during colorectal surgery.Methods
We conducted a 4- to 8-year follow-up of 204 patients with colorectal cancer who were randomly assigned to 65% nitrous oxide (n = 97) or nitrogen (n = 107), balanced with isoflurane and remifentanil. The primary outcome was the time to cancer recurrence. Our primary analysis was a multivariable Cox-proportional-hazards regression model that included relevant baseline variables. In addition to treatment group, the model considered patient age, tumor grade, dissemination, adjacent organ invasion, vessel invasion, and the number of nodes involved. The study had 80% power to detect a 56% or greater reduction in recurrence rates (i.e., hazard ratio of 0.44 or less) at the 0.05 significance level.Results
After adjusting for significant baseline covariables, risk of recurrence did not differ significantly for nitrous oxide and nitrogen, with a hazard ratio estimate (95% CI) of 1.10 (0.66, 1.83), P = 0.72. No two-way interactions with the treatment were statistically significant.Conclusion
Colorectal-cancer recurrence risks were not greatly different in patients who were randomly assigned to 65% nitrous oxide or nitrogen during surgery. Our results may not support avoiding nitrous oxide use to prevent recurrence of colorectal cancer.Implications Statement
The risk of colorectal cancer recurrence was similar in patients who were randomly assigned to 65% nitrous oxide or nitrogen during colorectal surgery.Trial Registration
Current Controlled Clinical Trials NCT00781352 http://www.clinicaltrials.gov 相似文献18.
Toivonen Raine Koskenvuo Juha Merentie Mari Söderström Mirva Ylä-Herttuala Seppo Savontaus Mikko 《Virology journal》2012,9(1):1-9
Background
Human immunodeficiency virus type 1 (HIV-1) Nef-encoded protein plays key functions at almost all stages of the viral life cycle, but its role in translation is largely unknown.Methods
To determine the effect of Nef on translation we used an in vitro translation assay. The detection of Nef/RPS10 complexes and the presence of 18S rRNA and tRNAs in the complexes were performed by coimmunoprecipitation and RT-PCR assay.Results
We observed that the HIV-1 Nef protein specifically impaired translation in vitro. We observed the interaction of Nef with RPS10 by coimmunoprecipitation assay. In addition 18S rRNA and tRNAs were present in the Nef/RPS10 complexes.Conclusions
Our results are consistent with a model in which the Nef protein by binding to two components of the 40S small ribosomal subunit, RPS10 and 18S rRNA, and to a lesser extent to tRNAs, could lead to decreased protein synthesis. 相似文献19.
Background and aims
Plant physiological traits and their relation to soil N availability was investigated as regulators of the distribution of understory shrub species along a slope in a Japanese cedar (Cryptomeria japonica) plantation in central Japan.Methods
At the study site, previous studies demonstrated that both net and gross soil nitrification rates are high on the lower slope and there are dramatic declines in different sections of the slope gradient. We examined the distributions of understory plant species and their nitrate (NO 3 ? -N) use traits, and compared the results with the soil traits.Results
Our results show that boundaries between different dominant understory species correspond to boundaries between different soil types. Leucosceptrum stellipilum occurs on soil with high net and gross nitrification rates. Hydrangea hirta is dominant on soil with high net and low gross nitrification rates. Pieris japonica occurs on soil with very low net and gross nitrification rates. Dominant understory species have species-specific physiological traits in their use of NO 3 ? -N. Pieris japonica lacks the capacity to use NO 3 ? -N as a N source, but other species do use NO 3 ? -N. Lindera triloba, whose distribution is unrelated to soil NO 3 ? -N availability, changes the extent to which it uses NO 3 ? -N in response to soil NO 3 ? -N availability.Conclusions
Our results indicate that differences in the physiological capabilities and adaptabilities of plant species in using NO 3 ? -N as a N source regulate their distribution ranges. The identity of the major form of available soil N is therefore an environmental factor that influences plant distributions. 相似文献20.