The expression profile of the <Emphasis Type="Italic">Tuber borchii</Emphasis> nitrite reductase suggests its positive contribution to host plant nitrogen nutrition

Ectomycorrhizal symbiosis is a ubiquitous association between plant roots and numerous fungal species. One of the main aspects of the ectomycorrhizal association are the regulation mechanisms of fungal genes involved in nitrogen acquisition. We report on the genomic organisation of the nitrate gene cluster and functional regulation of tbnir1, the nitrite reductase gene of the ectomycorrhizal ascomycete Tuber borchii. The sequence data demonstrate that clustering also occurs in this ectomycorrhizal fungus. Within the TBNIR1 protein sequence, we identified three functional domains at conserved positions: the FAD box, the NADPH box and the two (Fe/S)-siroheme binding site signatures. We demonstrated that tbnir1 presents an expression pattern comparable to that of nitrate transporter. In fact, we found a strong down-regulation in the presence of primary nitrogen sources and a marked tbnir1 mRNA accumulation following transfer to either nitrate or nitrogen limited conditions. The real-time PCR assays of tbnir1 and nitrate transporter revealed that both nitrate transporter and nitrite reductase expression levels are about 15-fold and 10-fold higher in ectomycorrhizal tissues than in control mycelia, respectively. The results reported herein suggest that the symbiotic fungus Tuber borchii contributes to improving the host plant’s ability to make use of nitrate/nitrite in its nitrogen nutrition.     

Allergy,total serum immunoglobulin E,and airflow in children and adolescents in TENOR

Haselkorn T, Szefler SJ, Simons FER, Zeiger RS, Mink DR, Chipps BE, Borish L, Wong DA, for the TENOR Study Group. Allergy, total serum immunoglobulin E, and airflow in children and adolescents in TENOR.
Pediatr Allergy Immunol 2010: 21: 1157–1165.
© 2010 John Wiley & Sons A/S In children and adolescents with difficult‐to‐treat asthma, few data exist characterizing the relationships between basic patient characteristics (e.g., age, sex) and atopic indicators in asthma. These associations were examined in The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens (TENOR), an observational study of a large cohort of patients with severe or difficult‐to‐treat asthma. To characterize allergy patterns and the relationship between total serum immunoglobulin E (IgE) and airflow in young patients with severe or difficult‐to‐treat asthma. A total of 1261 patients from the TENOR study were stratified into four age groups at baseline (6–8, 9–11, 12–14, and 15–17 yr). The objective was to characterize allergy patterns and the relationship between total serum immunoglobulin E (IgE) and ratio of pre‐bronchodilator forced expiratory volume in 1 second to forced vital capacity (FEV₁/FVC) in young patients with severe or difficult‐to‐treat asthma. The chi‐square test for categorical variables and analysis of variance for continuous variables were used to identify significant differences among age groups. Multivariable linear regression was used to evaluate the association between IgE and FEV₁/FVC. Allergic rhinitis was reported in approximately two‐thirds of patients. Up to 25% of patients had atopic dermatitis, which differed across age groups in boys (p < 0.05). Positive allergen skin test rate differed across age groups in boys (p < 0.05). Rates of asthma triggers were higher and differed across age groups in girls (p < 0.05), particularly around menarche (12–14 yr). IgE levels were higher in boys and differed across age groups in boys (p < 0.01) and girls (p < 0.05). IgE was associated with a lower FEV₁/FVC after adjusting for age and sex (p < 0.01). Severe or difficult‐to‐treat asthma in children and adolescents is characterized by high frequencies of comorbid allergic diseases, allergen sensitization, and high IgE levels. This burden is amplified by the association of more airflow limitation with higher IgE levels, suggesting the need for allergy evaluations.     

Characteristics of contraceptive acceptors in an urban Nigerian setting

Intensive efforts in promoting family planning concepts and contraceptive delivery in the Third World over the past two- and one-half decades have yielded only token dividends . This has occurred in Nigeria, despite the favorable government attitude. A study of the characteristics of current contraceptive acceptors showed an overwhelming percentage of acceptors are uneducated , married and from the lower socioeconomic class, a striking departure from usual expectations. Most acceptors prefer oral contraceptives. The status of acceptance of modern contraception by the educated population is still undetermined. Contraceptives appeared to be used primarily by women aged 30 and older in our population.     

Mental health problems, obstructive lung disease and lung function: findings from the general population

Objective

There is cumulative evidence for a strong association of obstructive lung disease, i.e. asthma and COPD, with poor mental health, particularly with anxiety disorders and major depression. However, studies relating mental health problems to objective measures of lung function as assessed by spirometry are lacking.

Methods

The 12-month prevalence of specific psychopathological syndromes among 1772 adults from the general population was estimated by a structured interview. Additionally, participants underwent spirometry and were asked about obstructive lung disease in the year prior to the study. Logistic and linear regression models were used to relate obstructive lung disease and spirometrically defined airway obstruction to mental health problems.

Results

Mental health problems were found in 35.7% of the participants. After adjusted for sociodemographic, clinical and life-style factors, asthma and chronic bronchitis were associated with almost all domains of mental health problems. In contrast, independent of its definition, spirometric airflow limitation was only related to generalized anxiety (odds ratios ranging from 2.3 to 2.7). A reduced ratio of forced expiratory volume in one second to forced vital capacity was associated with mental health problems in general and panic and general anxiety in particular.

Conclusion

Our findings suggest an association of objective measure of airflow limitation to generalized anxiety and panic. While the causal relationship between obstructive lung disease, airflow limitation and anxiety remains to be determined, clinicians should pay diagnostic attention to the significant overlap of these conditions.     

“有诸内，必形诸外”的价值及其局限性

在明确“有诸内,必形诸外”哲学命题的本质、肯定该命题的中医学应用价值的基础上,从哲学与临床的角度全面剖析了“有诸内者,必形诸外”的局限性,即统一仅仅是内与外、现象与本质之间相互关系的一个方面,既对立又统一才是两者关系的全部和本质,这就是为什么临床上有“有诸内不形诸外”的情形存在;另一方面,内与外、现象与本质之间的统一又存在着一定程度的复杂性。以“有诸内,必形诸外”为前提的中医学“以表知里”方法有其自身利弊短长,医者当扬长而避短。     

Teamwork in the viscous oceanic microscale

Nutrient acquisition is crucial for oceanic microbes, and competitive solutions to solve this challenge have evolved among a range of unicellular protists. However, solitary solutions are not the only approach found in natural populations. A diverse array of oceanic protists form temporary or even long-lasting attachments to other protists and marine aggregates. Do these planktonic consortia provide benefits to their members? Here, we use empirical and modeling approaches to evaluate whether the relationship between a large centric diatom, Coscinodiscus wailesii, and a ciliate epibiont, Pseudovorticella coscinodisci, provides nutrient flux benefits to the host diatom. We find that fluid flows generated by ciliary beating can increase nutrient flux to a diatom cell surface four to 10 times that of a still cell without ciliate epibionts. This cosmopolitan species of diatom does not form consortia in all environments but frequently joins such consortia in nutrient-depleted waters. Our results demonstrate that symbiotic consortia provide a cooperative alternative of comparable or greater magnitude to sinking for enhancement of nutrient acquisition in challenging environments.

Global models of oxygen and carbon dioxide alterations depend upon transfer rates between small phytoplankton cells and surrounding surface waters of the world’s oceans (1–3). Although these cells are important on large scales, their individual interactions occur at microscopic dimensions that are dominated by viscosity. In this viscous environment, critical cellular processes, such as the exchange of nutrients, metabolites, and wastes, rely upon diffusion (4). While diffusion is an effective means of nutrient transport for the smallest microbes (5), it also creates a depleted region around the cell surface, referred to as the diffusion boundary layer (DBL), that limits nutrient consumption and cell growth (6, 7). The DBL for a cell at rest extends nine cell radii from the cell surface before the nutrient concentration reaches 90% of ambient levels (8), creating formidable disadvantages for nutrient acquisition by large cells requiring nutrient diffusion across large distances relative to their cell size (9). Phytoplankton have evolved mechanisms to mitigate the limitations of diffusive transfer rates by swimming or sinking (10) to generate relative motion between the cell and surrounding fluid. Diatoms—barrel-shaped, nonmotile eukaryotes—are considered to be one of the most ecologically important groups of phytoplankton (11–14) that absorb nutrients across their whole cell surface (15) but often increase sinking rates when experiencing nutrient limitation (16). Sinking thins the DBL surrounding the diatom cell and reduces the distance over which diffusion limits nutrient transport (8, 17). One potential disadvantage of this mechanism for DBL reduction is the high probability for a cell to sink out of sunlit regions, and sinking diatoms are major contributors to organic mass flux from surface to deep oceanic waters (1). A widespread but unevaluated alternative for such large cells involves teamwork with other smaller, motile cells that combine to form multicell consortia. Consortia are typically comprised of larger nonmotile host cells with smaller, surface-adhering motile cells termed epibionts. Although infrequently studied, epibionts are ubiquitous in the micrometer-scale world of planktonic organisms (18), and flagellated or ciliated epibionts often attach to larger objects (19) or marine snow (20). The selective forces favoring epibiont attachment remain in question. A range of fluid dynamic effects on prey encounter as well as biological factors such as reduced predator encounter risk or elevated prey availability surrounding host attachment sites have been proposed to explain the widespread nature of epibiont attachment (21, 22). However, the movement of motile epibiont cilia or flagella alters flows and, hence, creates an altered fluid dynamic environment surrounding the consortia. What are the consequences for the consortium host—does a larger, nonmotile cell benefit by membership in consortia? While advantages to the epibiont have been examined, the impacts on the host cells within a consortium have remained largely unconsidered. One reason for this is that physical associations between members of consortia are often temporary, and the short time scales of these relationships have hampered direct evaluation of the fluid mechanical interactions between consortium members.Here, we describe experimental work in combination with mathematical models that quantify the effect of the epibiont’s advective currents on nutrient availability to host cells within consortia formed by a large diatom, Coscinodiscus wailesii, and its peritrich ciliate epibiont, Pseudovorticella coscinodisci (Fig. 1A). Consortia composed of C. wailesii and P. coscinodisci are common along the Atlantic coast of South America (23, 24) and have provided a valuable opportunity for measuring fluid interactions characterizing a planktonic host–epibiont association.Open in a separate windowFig. 1.Diatom–ciliate association: (A) diatom C. wailesii and its epibiont P. coscinodisci. Scale bars represent 100 microns in length. (B) Flow around a single ciliate directed toward the diatom cell surface. (C) Velocity field for the same diatom–ciliate pair with a blue line indicating the transect line used for measurement of flow field velocities. The magenta segment represents the microcurrent component that directly intercepts the ciliary crown.     

Linear and nonlinear analysis of pressure and flow during mechanical ventilation

Objective: Linear modeling as a method of exploring respiratory mechanics during mechanical ventilation, was compared to nonlinear modeling for flow dependence of resistance in three distinct groups of patients, those with: (a) normal respiratory function (NRF), (b) chronic obstructive pulmonary disease (COPD), or (c) adult respiratory distress syndrome (ARDS). Design and patients: Airways opening pressure (Pao), flow (V′), and volume (V) signals were recorded in 32 ICU mechanically ventilated patients, under sedation and muscle relaxation (10 NRF, 11 COPD, 11 ARDS). All patients were ventilated with controlled mandatory ventilation mode at three levels of end-expiratory pressure (PEEPe): 0, 5, and 10 hPa. Data were analyzed according to: (a) Pao = PE + Ers V + Rrs V′ and (b) Pao = PE + Ers V + k ₁V′ + k ₂|V′|V′, where Ers and Rrs represent the intubated respiratory system (RS) elastance and resistance, k ₁ and k ₂ the linear and the nonlinear RS resistive coefficients, and PE the end-expiratory pressure. The model's goodness of fit to the data was evaluated by the root mean square difference of predicted minus measured Pao values. Results: NRF data fit both models well at all PEEPe levels. ARDS and particularly COPD data fit the nonlinear model better. Values of k ₂ were often negative in COPD and ARDS groups, and they increased in parallel with PEEPe. A gradual increase in PEEPe resulted in better fit of ARDS and COPD data to both models. Conclusions: The model of V′ dependence of resistance is more suitable for the ARDS and particularly the COPD groups. PEEP tends to diminish the V′ dependence of respiratory resistance during the respiratory cycle, particularly in the COPD group, probably through an indirect effect of the increased lung volume. Received: 14 June 1999 Final revision received: 19 November 1999 Accepted: 11 April 2000     

Cardiorespiratory and sensory responses to exercise in well-controlled asthmatics

Objectives: The purpose of this study was to evaluate detailed ventilatory, cardiovascular and sensory responses to cycle exercise in sedentary patients with well-controlled asthma and healthy controls. Methods: Subjects included sedentary patients meeting criteria for well-controlled asthma (n?=?14), and healthy age- and activity-matched controls (n?=?14). Visit 1 included screening for eligibility, medical history, anthropometrics, physical activity assessment, and pre- and post-bronchodilator spirometry. Visit 2 included spirometry and a symptom limited incremental cycle exercise test. Detailed ventilatory, cardiovascular and sensory responses were measured at rest and throughout exercise. Results: Asthmatics and controls were well matched for age, body mass index and physical activity levels. Baseline forced expiratory volume in 1?second (FEV₁) was similar between asthmatics and controls (98?±?10 versus 95?±?9% predicted, respectively, p?>?0.05). No significant differences were observed between asthmatics and controls for maximal oxygen uptake (31.8?±?5.6 versus 30.6?±?5.9?ml/kg/min, respectively, p?>?0.05) and power output (134?±?35 versus 144?±?32?W, respectively, p?>?0.05). Minute ventilation (V_E) relative to maximum voluntary ventilation (V_E/MVV) was similar between groups at maximal exercise with no subjects showing evidence of ventilatory limitation. Asthmatics and controls achieved similar age-predicted maximum heart rates (92?±?7 versus 93?±?8% predicted, respectively, p?>?0.05). Ratings of perceived breathing discomfort and leg fatigue were not different between groups throughout exercise. Conclusions: The results of this study indicate that sedentary patients with well-controlled asthma have preserved sensory and cardiorespiratory responses to exercise with no evidence of exercise impairment or ventilatory limitation.