MR弥散加权成像对鉴别诊断良恶性椎体压缩性骨折的临床价值研究

目的：探讨MR弥散加权成像（DWI）鉴别诊断良恶性椎体压缩性骨折的临床价值。方法：对57例经临床或病理证实的椎体良恶性压缩性骨折患者行矢状位T1M、T2WI、T2WI／FS及DWI扫描,研究其在常规序列和DWI序列上的表现,将常规MR序列和DWI序列检出率进行比较,测量正常椎体及病变椎体的表观弥散系数（ADC）值,并进行统计学分析。结果：（1）MR常规序列和DWI序列（b=500s／mm2）表现：良性椎体压缩性骨折呈长T1长或等T2改变,T2WI／FS呈高信号,DWI可以呈高信号、等信号及低信号;恶性椎体压缩性骨折呈长T1长T2信号,大部分病灶T2WUFS及DWI呈高信号,少数变现为低信号;（2）MR常规序列和DWI序列（b=500s／mm2）病灶检出率的比较：T1WI、T2WI／FS及DWI序列病灶检出率均高于T2WI序列,其间的差别有显著性意义（P〈0．01）,T1WI、T2WI／FS及DWI序列病灶检出率之间无显著性差异（P〉0．01）;（3）ADC值比较：在DWI（b=500s／mm2）上,良性组ADC值为（2．03±0．83）×10^3mm^2/s,恶性组ADC值为（1．37±0．75）×10^-3mm^2/s,正常组ADC值为（0．36±0．21）×10^-3mm^2／s,成像条件相同时,良性组高于恶性组,两组间有明显的统计学意义（P〈0．05）。结论：DWI可较好的反映椎体的弥散特征,ADC值作为量化指标可对良恶性椎体压缩性骨折进行可靠鉴别。     

Refinement of the MHC Risk Map in a Scandinavian Primary Sclerosing Cholangitis Population

Background

Genetic variants within the major histocompatibility complex (MHC) represent the strongest genetic susceptibility factors for primary sclerosing cholangitis (PSC). Identifying the causal variants within this genetic complex represents a major challenge due to strong linkage disequilibrium and an overall high physical density of candidate variants. We aimed to refine the MHC association in a geographically restricted PSC patient panel.

Methodology/Principal Findings

A total of 365 PSC cases and 368 healthy controls of Scandinavian ancestry were included in the study. We incorporated data from HLA typing (HLA-A, -B, -C, -DRB3, -DRB1, -DQB1) and single nucleotide polymorphisms across the MHC (n = 18,644; genotyped and imputed) alongside previously suggested PSC risk determinants in the MHC, i.e. amino acid variation of DRβ, a MICA microsatellite polymorphism and HLA-C and HLA-B according to their ligand properties for killer immunoglobulin-like receptors. Breakdowns of the association signal by unconditional and conditional logistic regression analyses demarcated multiple PSC associated MHC haplotypes, and for eight of these classical HLA class I and II alleles represented the strongest association. A novel independent risk locus was detected near NOTCH4 in the HLA class III region, tagged by rs116212904 (odds ratio [95% confidence interval] = 2.32 [1.80, 3.00], P = 1.35×10⁻¹¹).

Conclusions/Significance

Our study shows that classical HLA class I and II alleles, predominantly at HLA-B and HLA-DRB1, are the main risk factors for PSC in the MHC. In addition, the present assessments demonstrated for the first time an association near NOTCH4 in the HLA class III region.     

Nitrogen fixation of lucerne (Medicago sativa) in an acid soil: The use of rhizotrons as a model system to simulate field conditions

The effect of pelleting seeds of lucerne with lime was studied in an acid sandy soil. In pot experiments, the fraction of seedlings with crown nodules, i.e. nodules on the upper 10 mm of the taproot, increased from 26% to 71%. In rhizotrons, the application of CaCO₃ resulted in an even stronger response.An agar-contact method was used to study pH changes in the rhizosphere during a period up to 12 days. Application of 1.0 µmol of CaCO₃, in drops of 12 µL volume, resulted in an initial soil pH of 6.1 and yielded 75% crown nodulation. In the absence of CaCO₃, roots induced a pH increase from 5.1 (day 0) to 5.7 (day 12). However, this did not increase nodulation (5%). Obviously, this type of alkalinization does not overcome the acid-sensitive step of the nodulation process.     

Nodulation of lucerne (Medicago sativa L.) in an acid soil: pH dynamics in the rhizosphere of seedlings growing in rhizotrons

A lime-pellet around seeds of lucerne significantly increased crown nodulation in an acid soil. To investigate whether neutralization or calcium were of importance when lime was supplied, experiments with plants were done either in pots or in rhizotrons. Crown nodulation was used to quantify the effect of these two parameters.For the neutralization of the soil, KOH (in pots) or K₂CO₃ (in rhizotrons) was added. The crown nodulation of pot-grown plants increased from 31% to 53%. In rhizotrons, the number of crown-nodulated seedlings increased from 9% to 53%. If calcium was supplied additionally (as CaCl₂ or CaSO₄), 63% crown nodulation was found in pots, and 68% in rhizotrons. These numbers are close to the crown nodulation with lime (CaCO₃) alone: 70% in pots and 71% in rhizotrons. In the soil studied, the beneficial effect of lime is largely due to neutralization (80%), and only a minor part (20%) is due to the input of calcium.Using rhizotrons, the dynamics of the pH in the rhizosphere of lime-treated and untreated seedlings was followed during a period of 12 days. It was found that, even in the absence of lime, the pH along the taproot increased from 5.1 to 5.7. However, this did not result in the formation of root nodules. Nodulation was obtained only by adding neutralizing chemicals, which increased the pH during the initial 3 days, the acid sensitive period of the process.     

Shift from facilitative to neutral interactions by the cushion plant Silene acaulis along a primary succession gradient

Background

The stress‐gradient hypothesis predicts a shift from facilitative to competitive plant interactions with decreasing abiotic stress. This has been supported by studies along elevation and temperature gradients, but also challenged by the hypothesis of a facilitation collapse at extremely harsh sites. Although facilitation is known to be important in primary succession, few studies have examined these hypotheses along primary succession gradients.

Aim

To examine whether there is a relationship between the presence of the circumpolar cushion plant Silene acaulis and other species, and if so, whether there is a shift between positive and negative interactions along a primary succession gradient in a glacier foreland.

Location

Finse, southern Norway.

Methods

We examined the performance of the common alpine forb Bistorta vivipara, species richness of vascular plants, bryophytes and lichens, and the number of seedlings and fertile vascular plants in S. acaulis cushions, and control plots without S. acaulis, along a succession gradient with increasing distance from a glacier front, and thus decreasing abiotic stress. To examine if S. acaulis cushions modify the abiotic environment, we recorded soil temperature, moisture, organic content and pH in cushions and control plots.

Results

Bistorta vivipara performed better, as shown by bigger leaves in S. acaulis cushions compared to control plots in the harshest part of the gradient close to the glacier. There were few differences in B. vivipara performance between cushion and control plots in the more benign environment further away from the glacier. This suggests a shift from facilitative to mainly neutral interactions by S. acaulis on the performance of B. vivipara with decreasing abiotic stress. A trend, although not significant, of higher vascular species richness and fertility inside S. acaulis cushions along the whole gradient, suggests that S. acaulis also facilitates community‐level species richness. The causal mechanism of this facilitation is likely that the cushions buffer extreme temperatures.

Conclusions

Our results support the stress‐gradient hypothesis for the relationship between the cushion plant S. acaulis and the performance of a single species along a primary succession gradient in a glacier foreland. S. acaulis also tended to increase vascular plant species richness and fertility regardless of stress level along the gradient, suggesting facilitation at the community level. We found no collapse of facilitation at the most stressful end of the gradient in this alpine glacier foreland.     

The association of sleepiness,insomnia, sleep disturbance and pain: a study amongst shiftworking nurses

Sleep and Biological Rhythms - Sleep problems are commonly associated with chronic pain. It is not known whether pain is more related to a particular type of sleep problem or to more composite...