Imaging characteristics and prognostic factors of Behcet's disease with arterial involvement: A long-term follow-up study.

PURPOSE: To investigate the imaging characteristics and prognostic factors for the long-term survival of Behcet's disease (BD) with arterial involvement. METHODS: In this retrospective study, BD patients with arterial involvement were identified from January 2003 to January 2020. Arterial lesions were detected by ultrasonography, traditional arteriography, and/or computed tomography angiography (CTA). Cox proportional hazards regression analyses were performed to identify the prognostic factors. RESULTS: Totally, 84 BD patients with arterial involvement were identified (73.8 % males). The mean age at BD diagnosis was 39.1 ± 13.1 years. Arterial involvement was the initial manifestation in 33.3 % of the patients, and the median time from BD diagnosis to arterial involvement was 6 (IQR 1-15.5) years for the rest of patients. Systemic artery involvement and pulmonary artery involvement (PAI) were found in 64 and 27 patients, respectively. Approximately 94.0 % (79/84) of the patients had more than one artery involved concurrently or successively during the course of BD. Aneurysm/dilation was the most prevalent lesion in the aorta (76.0 %), while stenosis/occlusion was the main lesion of the coronary artery (90.9 %) and other aortic branches (74.5 %). Pulmonary hypertension was found in 70.4 % (19/27) of patients with PAI. The 5- and 10-year survival rates of BD patients with arterial involvement were 87.4 % and 84.1 %, respectively. Cardiac involvement (HR: 4.34) and pulmonary artery aneurysm/dilation (HR: 4.89) were independently associated with mortality. CONCLUSIONS: Arterial lesions associated with BD usually involve multiple arteries and manifest differently in different types of arteries. Cardiac involvement and pulmonary artery aneurysm/dilation are independent prognostic factors of BD patients with arterial involvement.

An approach for proteins and their encoding genes synonyms integration based on protein ontology.

BACKGROUND: Biological research is generating high volumes of data distributed across various sources. The inconsistent naming of proteins and their encoding genes brings great challenges to protein data integration: proteins and their coding genes usually have multiple related names and notations, which are difficult to match absolutely; the nomenclature of genes and proteins is complex and varies from species to species; some less studied species have no nomenclature of genes and proteins; The annotation of the same protein/gene varies greatly in different databases. In summary, a comprehensive set of protein/gene synonyms is necessary for relevant studies. RESULTS: In this study, we propose an approach for protein and its encoding gene synonym integration based on protein ontology. The workflow of protein and gene synonym integration is composed of three modules: data acquisition, entity and attribute alignment, attribute integration and deduplication. Finally, the integrated synonym set of proteins and their coding genes contains over 128.59 million terminologies covering 560,275 proteins/genes and 13,781 species. As the semantic basis, the comprehensive synonym set was used to develop a data platform to provide one-stop data retrieval without considering the diversity of protein nomenclature and species. CONCLUSION: The synonym set constructed here can serve as an important resource for biological named entity identification, text mining and information retrieval without name ambiguity, especially synonyms associated with well-defined species categories can help to study the evolutionary relationships between species at the molecular level. More importantly, the comprehensive synonyms set is the semantic basis for our subsequent studies on Protein-protein Interaction (PPI) knowledge graph.

Meta-analysis reveals variations in microbial communities from diverse stony coral taxa at different geographical distances.

Coral-associated microbial communities play a vital role in underpinning the health and resilience of reef ecosystems. Previous studies have demonstrated that the microbial communities of corals are affected by multiple factors, mainly focusing on host species and geolocation. However, up-to-date, insight into how the coral microbiota is structured by vast geographic distance with rich taxa is deficient. In the present study, the coral microbiota in six stony coral species collected from the coastal area of three countries, including United States of America (USA), Australia and Fiji, was used for analysis. It was found that the geographic influence on the coral microbiota was stronger than the coral host influence, even though both were significant. Interestingly, the contribution of the deterministic process to bacterial community composition increased as geographical distance grew. A total of 65 differentially abundant features of functions in coral microbial communities were identified to be associated with three geolocations. While in the same coastal area of USA, the similar relationship of coral microbiota was consistent with the phylogenetic relationship of coral hosts. In contrast to the phylum Proteobacteria, which was most abundant in other coral species in USA, Cyanobacteria was the most abundant phylum in Orbicella faveolata. The above findings may help to better understand the multiple natural driving forces shaping the coral microbial community to contribute to defining the healthy baseline of the coral microbiome.

10-year survival of pulmonary arterial hypertension associated with connective tissue disease: insights from a multicentre PAH registry.

OBJECTIVES: To report the 10-year survival rate and prognostic factors of pulmonary arterial hypertension associated with CTD (CTD-PAH) patients, to compare treatment and survival between patients enrolled before and after 2015, and to validate the discrimination of the recommended four-strata model in predicting 10-year survival at follow-up in Chinese CTD-PAH patients. METHODS: This study was derived from a Chinese national multicentre prospective registry study from 2009 to 2019. Medical records were collected at baseline and follow-up, including PAH-targeted therapy and binary therapy (both CTD and PAH-targeted therapy). RESULTS: A total of 266 CTD-PAH patients were enrolled and the 10-year survival rate was 59.9% (median follow-up time: 4.85 years). Underlying CTD (SSc), baseline 6-min walking distance and SaO2 were independent risk factors for 10-year survival. The proportion of patients receiving PAH-targeted combination therapy increased from 10.1% (2009-2014) to 26.5% (2015-2019) and that of binary therapy increased from 14.8% to 35%. The 1-year survival rate increased from 89.8% (2009-2014) to 93.9%, and the 3-year survival rate increased from 80.1% (2009-2014) to 86.5% (both P > 0.05). The four-strata strategy performed well in predicting 10-year survival at follow-up (C-index = 0.742). CONCLUSION: The 10-year survival rate of CTD-PAH patients was reported for the first time. The 10-year prognosis was poor, but there was a tendency for more standardized treatment and better survival in patients enrolled after 2015. The recommended four-strata model at follow-up can effectively predict 10-year survival in CTD-PAH patients.

Single-shot 3D imaging with point cloud projection based on metadevice.

Three-dimensional (3D) imaging is a crucial information acquisition technology for light detection, autonomous vehicles, gesture recognition, machine vision, and other applications. Metasurface, as a subwavelength scale two-dimensional array, offers flexible control of optical wavefront owing to abundant design freedom. Metasurfaces are promising for use as optical devices because they have large field of view and powerful functionality. In this study, we propose a flat optical device based on a single-layer metasurface to project a coded point cloud in the Fourier space and explore a sophisticated matching algorithm to achieve 3D reconstruction, offering a complete technical roadmap for single-shot detection. We experimentally demonstrate that the depth accuracy of our system is smaller than 0.24 mm at a measurement distance of 300 mm, indicating the feasibility of the submillimetre measurement platform. Our method can pave the way for practical applications such as surface shape detection, gesture recognition, and personal authentication.

Design method for the high optical efficiency and uniformity illumination system of the projector.

How to balance the optical efficiency, illumination uniformity and the size of the illumination system is a challenging task in projector design. In this paper, we present a mathematical model describing the relationship between optical energy of the illumination system and the optical parameters and an optimization design method considering the light intensity distribution of the light source. By using the proposed method, two illumination systems are designed with different types of the digital micromirror device chips. In addition, we also propose a non-coaxial system to solve the deformation problem caused by the large flip angle of the DMD chip and further improve the illumination uniformity based on Scheimpflug principle. The optical efficiency and illumination uniformity of the illumination systems were verified and analyzed. The results indicate that the systems designed by the proposed method can provide a good design scheme and obtain a satisfactory utilization rate of the optical energy and higher uniformity.

Supplementation with Iron in Pulmonary Arterial Hypertension. Two Randomized Crossover Trials.

Rationale: Iron deficiency, in the absence of anemia, is common in patients with idiopathic and heritable pulmonary arterial hypertension (PAH) and is associated with a worse clinical outcome. Oral iron absorption may be impeded by elevated circulating hepcidin concentrations. The safety and benefit of parenteral iron replacement in this patient population is unclear. Objectives: To evaluate the safety and efficacy of parenteral iron replacement in PAH. Methods: In two randomized, double-blind, placebo-controlled 12-week crossover studies, 39 patients in Europe received a single infusion of ferric carboxymaltose (Ferinject) (1,000 mg or 15 mg/kg if weight <66.7 kg) or saline as placebo, and 17 patients in China received iron dextran (Cosmofer) (20 mg iron/kg body weight) or saline placebo. All patients had idiopathic or heritable PAH and iron deficiency at entry as defined by a serum ferritin <37 µg/L or iron <10.3 µmol/L or transferrin saturations <16.4%. Results: Both iron treatments were well tolerated and improved iron status. Analyzed separately and combined, there was no effect on any measure of exercise capacity (using cardiopulmonary exercise testing or 6-minute walk test) or cardiopulmonary hemodynamics, as assessed by right heart catheterization, cardiac magnetic resonance, or plasma NT-proBNP (N-terminal-pro hormone brain natriuretic peptide) at 12 weeks. Conclusions: Iron repletion by administration of a slow-release iron preparation as a single infusion to patients with PAH with iron deficiency without overt anemia was well tolerated but provided no significant clinical benefit at 12 weeks. Clinical trial registered with ClinicalTrials.gov (NCT01447628).

Nestin represents a potential marker of pulmonary vascular remodeling in pulmonary arterial hypertension associated with congenital heart disease.

OBJECTIVE: Reportedly, nestin was re-expressed in proliferative synthetic-type pulmonary artery smooth muscle cells (PASMCs) and obligatory for PASMC proliferation in pulmonary arterial hypertension (PAH). Accordingly, nestin is increased in pulmonary vascular lesions of congenital heart disease (CHD)-associated PAH patients. We tested the hypothesis whether nestin was re-expressed in proliferative synthetic-type PASMCs and associated with pulmonary vascular remodeling in CHD-PAH. MATERIALS AND METHODS: Nestin expression was tested using lung tissues from CHD-PAH patients and monocrotaline (MCT) plus aortocaval (AV) shunt-induced PAH rats, human PASMCs (HPASMCs), and pulmonary artery endothelial cells (PAECs) and PASMCs from MCT-AV-induced PAH rats. The role and possible mechanism of nestin on HPASMC proliferation, apoptosis, cell cycle and migration were investigated by assays of CCK-8, EdU, TUNEL, flow cytometry, transwell chamber and immunoblotting assays. RESULTS: Nestin was solely expressed in proliferative synthetic-type PASMCs, but rarely detected in PAECs. Nestin was barely detected in normal pulmonary arterioles and occlusive pulmonary vascular lesions. Its expression was robustly increased in developing pulmonary vasculature, but returned to normal levels at the late stage of pulmonary vascular remodeling in lung tissues from CHD-PAH patients and MCT-AV-induced PAH rats. Besides, nestin peaks were consistent with the histological features in lung tissues of MCT-AV-induced PAH rats. Moreover, nestin overexpression effectively promoted HPASMC phenotypic transformation, proliferation, apoptosis resistance and migration via enhancing Wnt/ß-catenin activation. CONCLUSIONS: These data indicated that nestin was re-expressed in proliferative synthetic-type PASMCs and might represent a potential marker of pulmonary vascular remodeling in CHD-PAH.

A case of ANCA associated vasculitis in a patient presenting with chest pain.

Antineutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV) is a group of multisystem autoimmune small vessel diseases. We report here a case of a 68-year-old woman who initially presented with 29-day history of chest pain, malaise and anorexia. Cardiac problems were ruled out and she was considered to have pneumonia. Her symptoms persisted and blood tests showed renal impairment and evidence of an inflammatory response. A kidney biopsy, chest computed tomography (CT) scan and ANCA testing confirmed a diagnosis of AAV renal injury. She was treated with glucocorticoids and cyclophosphamide (CTX) for six months at which time her kidney function had improved and she avoided the need for dialysis. This case study illustrates that the clinical manifestations of AVV are complex, varied, and prone to misdiagnosis.

Case report on a 32-year-old female with elevated serum creatinine levels and primary Sjögren's syndrome-chronic interstitial nephritis.

Primary Sjögren's syndrome (PSS) is a chronic autoimmune disease characterized by lymphoplasmacytic infiltration of the exocrine glands, which results in multiple organs damage. Renal injury affects 0.3-27.0% of PSS patients, and tubulointerstitial nephritis is the most frequent form of nephropathy in PSS. The present study reports on the case of a 32-year-old female with a 1-year history of elevated serum creatinine levels, and a 6-month history of mild pain in the waist and leg. Blood biochemistry tests indicated a creatinine level of 221.3 µmol/l and estimated glomerular filtration rate of 24.6 ml/min/1.73 m2 [Chronic Kidney Disease Epidemiology (CKD-EPI) formula]. Accordingly, the patient was diagnosed with stage IV chronic kidney disease. To clarify the underlying cause of the disease, a kidney biopsy was performed, which revealed tubular epithelial cells with multiple focal and lamellar atrophy (~60%), as well as extensive renal interstitial fibrosis with scattered inflammatory cell infiltration. Based on these results, the patient was finally diagnosed with severe chronic interstitial nephritis, chronic kidney disease stage IV, PSS and anemia due to chronic kidney disease. The patient was treated with half-dose glucocorticoid (prednisone, 25 mg oral qd maintained up to 12 months). The patient's serum creatinine levels had decreased to 172.4 µmol/l after 1 month and to 178.7 µmol/l after 12 months. The present case concluded that young patients with chronic renal failure should first be assessed for rheumatic immune system diseases. PSS may involve several organs and the clinical manifestations may be varied. Although chronic renal failure is frequently the first manifestation of renal disorder due to PSS, it may be overlooked by clinicians. The present results suggest that further attention should be paid to determine the association between symptoms in the clinical setting.

Mild hypothermia improves neurological outcome in mice after cardiopulmonary resuscitation through Silent Information Regulator 1-actviated autophagy.

Mild hypothermia treatment (MHT) improves the neurological function of cardiac arrest (CA) patients, but the exact mechanisms of recovery remain unclear. Herein, we generated a CA and cardiopulmonary resuscitation (CPR) mouse model to elucidate such function. Naïve mice were randomly divided into two groups, a normothemia (NT) group, in which animals had normal body temperature, and a MHT group, in which animals had a body temperature of 33 °C (range: 32-34 °C), after the return of spontaneous circulation (ROSC), followed by CA/CPR. MHT significantly improved the survival rate of CA/CPR mice compared with NT. Mechanistically, MHT increased the expression of Silent Information Regulator 1 (Sirt1) and decreased P53 phosphorylation (p-P53) in the cortex of CA/CPR mice, which coincided with the elevated autophagic flux. However, Sirt1 deletion compromised the neuroprotection offered by MHT, indicating that Sirt1 plays an important role. Consistent with the observations obtained from in vivo work, our in vitro study utilizing cultured neurons subjected to oxygen/glucose deprivation and reperfusion (OGD/R) also indicated that Sirt1 knockdown increased OGD/R-induced neuron necrosis and apoptosis, which was accompanied by decreased autophagic flux and increased p-P53. However, the depletion of P53 did not suppress neuron death, suggesting that P53 was not critically involved in MHT-induced neuroprotection. In contrast, the application of autophagic inhibitor 3-methyladenine attenuated MHT-improved neuron survival after OGD/R, further demonstrating that increased autophagic flux significantly contributes to MHT-linked neuroprotection of CA/CRP mice. Our findings indicate that MHT improves neurological outcome of mice after CA/CPR through Sirt1-mediated activation of autophagic flux.

Global Long-Term Care Research: A Scientometric Review.

Since the early 1960s, long-term care (LTC) has attracted a broad range of attention from public health practitioners and researchers worldwide and produced a large volume of literature. We conducted a comprehensive scientometric review based on 14,019 LTC articles retrieved from the Web of Science Core Collection database from 1963 to 2018, to explore the status and trends of global LTC research. Using CiteSpace software, we conducted collaboration analysis, document co-citation analysis, and keyword co-occurrence analysis. The results showed a rapid increase in annual LTC publications, while the annual citation counts exhibited an inverted U-shaped relationship with years. The most productive LTC research institutions and authors are located primarily in North American and European countries. A simultaneous analysis of both references and keywords revealed that common LTC hot topics include dementia care, quality of care, prevalence and risk factors, mortality, and randomized controlled trial. In addition, LTC research trends have shifted from the demand side to the supply side, and from basic studies to practical applications. The new research frontiers are frailty in elderly people and dementia care. This study provides an in-depth understanding of the current state, popular themes, trends, and future directions of LTC research worldwide.

Mesenchymal stem cells derived from induced pluripotent stem cells play a key role in immunomodulation during cardiopulmonary resuscitation.

BACKGROUND/AIMS: Previous in vitro experiments have demonstrated the immunomodulatory functions of mesenchymal stem cells derived from induced pluripotent stem cells (iPSC-MSCs) in brain injury. We have tried to further understand these functions by investigating the neuroprotective effects of iPSC-MSCs in a rat model of cardiac arrest (CA). METHODS: CA was induced in adult Sprague-Dawley rats by transcutaneous electrical epicardium stimulation. The rats were divided into four groups. In a separate cohort of sham operation animals, iPSC-MSCs or PBS was infused via the femoral vein after restoration of spontaneous circulation. Survival was evaluated every 2 h until 24 h after CA. Markers of classically activated macrophages (M1) and alternatively activated (M2) macrophages were assessed by qPCR and western blot analysis, and the gene expression profiles of the macrophages were studied in order to identify differentially expressed proteins. RESULTS: The 24-h survival rate was significantly different between the CPR group and iPSC-MSC group (P = 0.033). Additionally, a significant number of mRNAs were differentially expressed between the iPSC-MSC and PBS group. Compared with the sham operation group, both M1 (27/29) and M2 (2/29) mRNAs showed a significant increase in expression in the CPR group, while only M2 (22) mRNAs showed a significant increase in expression in the iPSC-MSC group. Western blotting analysis showed that the expression of Arg-1 and CD14 (M2 macrophage markers) was increased in the iPSC-MSC group (P < 0.05), while CD86 and iNOS (M1 macrophage markers) expression was increased in the CPR group (P < 0.05). CONCLUSION: IPSC-MSCs, which play a key role in immunomodulation, downregulate the level of M1 macrophages and upregulate the level of M2 macrophages after CA.

Etoposide combined with ruxolitinib for refractory hemophagocytic lymphohistiocytosis during pregnancy: a case report and literature review.

Hemophagocytic lymphohistiocytosis (HLH) is an immune-mediated disorder caused by uncontrolled inflammatory responses and the activation of T lymphocytes. This life-threatening disease, characterized by fever, cytopenia and hepatosplenomegaly, is extremely rare during pregnancy with high mortality. Despite the improvement of treatment regimen in recent years, HLH is still a great challenge for clinicians. Here, we described a 26-year-old woman who admitted to our hospital at her first pregnancy with pyrexia. Her condition continued to deteriorate after receiving broad-spectrum antimicrobials, presenting with fever, pancytopenia, hepatosplenomegaly, ferritin ≥ 500 µg/L, hemophagocytosis and low NK-cell activity. HLH was eventually diagnosed by clinical manifestation and laboratory examination results. Then the patient recovered well after treatment with etoposide combined with ruxolitinib therapy and underwent successful induced-labor operation. Additionally, we summarized similar cases from the literature to improve the management of HLH during pregnancy. In conclusion, this study highlights the challenges and difficulties in the diagnosis and management of patients with HLH during pregnancy. Moreover, this is the first case report of etoposide combined with ruxolitinib in the treatment of patients with refractory secondary HLH during pregnancy.

Shape reconstruction based on zero-curl gradient field estimation in a fringe reflection technique.

A novel shape reconstruction method based on zero-curl gradient field estimation is presented in this paper. Zero-curl field estimation makes the most of curl information to obtain the ideal gradient data, and achieves the reconstruction with the quality map path integration method. In the estimation process, an algebraic approach is adopted to enforce integrability, which maintains the local information well. Moreover, we use the residual gradients of surface obtained from the Southwell zonal reconstruction algorithm as the raw gradient data in zero-curl field estimation, which has a stable tradeoff between smoothness and local shape confinement. The performance of the proposed method over antinoise capability is discussed and demonstrated by the simulations. The measurement experiment of an ultraprecision sphere mirror identifies the validity over general shapes, and the reconstruction results of hyperbolic surface with a local shape map demonstrate the better performance on local details retention. Therefore, this method performs well in handling complex objects with local mutation regions and high accuracy requirement of local information in practical measurement.

Removal of millimeter-scale rolled edges using bevel-cut-like tool influence function in magnetorheological jet polishing.

Subaperture polishing techniques usually produce rolled edges due to edge effect. The rolled edges, especially those in millimeter scale on small components, are difficult to eliminate using conventional polishing methods. Magnetorheological jet polishing (MJP) offers the possibility of the removal of these structures, owing to its small tool influence function (TIF) size. Hence, we investigate the removal characters of inclined MJP jetting models by means of computational fluid dynamics (CFD) simulations and polishing experiments. A discrete phase model (DPM) is introduced in the simulation to get the influence of abrasive particle concentration on the removal mechanism. Therefore, a more accurate model for MJP removal mechanisms is built. With several critical problems solved, a small bevel-cut-like TIF (B-TIF), which has fine acentric and unimodal characteristics, is obtained through inclined jetting. The B-TIF proves to have little edge effect and is applied in surface polishing of thin rolled edges. Finally, the RMS of the experimental section profile converges from 10.5 nm to 1.4 nm, and the rolled edges are successfully suppressed. Consequently, it is validated that the B-TIF has remarkable ability in the removal of millimeter-scale rolled edges.

IPSC­MSC inhibition assessment in Raw 264.7 cells following oxygen and glucose deprivation reveals a distinct function for cardiopulmonary resuscitation.

Hypoxia is a serious stress state. The nervous system is less tolerant to hypoxia, and cell death due to hypoxia is irreversible. With the incidence of cardiovascular disease gradually increasing, the sudden cardiac death rate is additionally increasing. Although cardiopulmonary resuscitation (CPR) is an important development, recovery is frequently poor. In a successful recovery population, ~40% of the population was in a vegetative state or subsequently succumbed to their condition, and ~20% had brain damage. Therefore, the recovery of the brain is of particular importance in CPR. Immune disorders are one of the major mechanisms of cerebral resuscitation following CPR. Studies have demonstrated that induced pluripotent stem cell­derived mesenchymal stem cells (IPSC­MSCs) have a strong immune regulatory effect during tissue repair and anti­inflammatory effects. IPSC­MSCs may inhibit the inflammatory response by means of the inflammatory reaction network to improve brain function following CPR, although the cellular and molecular mechanisms remain unclear. Macrophages are a bridge between innate immune and specific immune responses in the body; therefore, it was hypothesized that macrophages may be the important effector cell of the role of IPSC­MSCs in improving brain function following recovery of spontaneous respiration and circulation subsequent to cardiopulmonary resuscitation. In the present study, IPSC­MSCs were applied to the oxygen and glucose deprivation (OGD) model. It was observed that intervention with IPSC­MSCs was able to alter the polarization direction of macrophages. The difference in the proportions of M1 and M2 macrophages was statistically significant at 6, 12, 24 and 48 h (P=0.037, P<0.05) in the OGD + IPSC­MSCs group (M1, 33.48±5.6%; M2, 50.84±6.9%) and in the OGD group (M1, 83.55±7.3%; M2, 11.41±3.2%), and over time this trend was more obvious. The polarization direction of macrophages is associated with the neurogenic locus notch homolog protein 1 (Notch­1) signaling pathway. In conclusion, it was observed that IPSC­MSCs may be associated with altered macrophage polarization, which may be accomplished by inhibiting the Notch­1 signaling pathway.

Correction: Utilization of urea and expression profiles of related genes in the dinoflagellate Prorocentrum donghaiense.

[This corrects the article DOI: 10.1371/journal.pone.0187837.].

Utilization of urea and expression profiles of related genes in the dinoflagellate Prorocentrum donghaiense.

Urea has been shown to contribute more than half of total nitrogen (N) required by phytoplankton in some estuaries and coastal waters and to provide a substantial portion of the N demand for many harmful algal blooms (HABs) of dinoflagellates. In this study, we investigated the physiological and transcriptional responses in Prorocentrum donghaiense to changes in nitrate and urea availability. We found that this species could efficiently utilize urea as sole N source and achieve comparable growth rate and photosynthesis capability as it did under nitrate. These physiological parameters were markedly lower in cultures grown under nitrate- or urea-limited conditions. P. donghaiense N content was similarly low under nitrate- or urea-limited culture condition, but was markedly higher under urea-replete condition than under nitrate-replete condition. Carbon (C) content was consistently elevated under N-limited condition. Consequently, the C:N ratio was as high as 21:1 under nitrate- or urea-limitation, but 7:1 under urea-replete condition and 9:1 to 10:1 under nitrate-replete condition. Using quantitative reverse transcription PCR, we investigated the expression pattern for four genes involved in N transport and assimilation. The results indicated that genes encoding nitrate transport, urea hydrolysis, and nickel transporter gene were sensitive to changes in general N nutrient availability whereas the urea transporter gene responded much more strongly to changes in urea concentration. Taken together, our study shows the high bioavailability of urea, its impact on C:N stoichiometry, and the sensitivity of urea transporter gene expression to urea availability.