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1.
Relationship Between Lateral Root Primordia in Different Ranks   总被引:2,自引:0,他引:2  
CHARLTON  W. A. 《Annals of botany》1987,60(4):455-458
Comparisons with theoretical random distributions indicate thatthe longitudinal positional relationships between lateral rootsin different ranks are random in roots of Musa acuminata, Pistiastratiotes and i, species in which lateral root primordia arisein the root tip. In Potentilla palustris, where lateral rootprimordia arise further back in the root, there is a deficiencyof close spacings, which indicates that there is some interactionbetween ranks. Musa acuminata, Pistia stratiotes, Pontederia cordat, Potentilla palustris, roots, lateral roots, pattern  相似文献   

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Because approximately 70% of uric acid is excreted from the kidney, hyperuricemia occurs when renal function deteriorates. Until now, it has not been clear if the hyperuricemia seen in such renal diseases plays a role in the progression of renal disease. However, recent clinical studies show that the serum uric acid value is closely associated with hypertension in hyperuricemic patients (cross-sectional study), and also with the onset of hypertension (longitudinal study). Furthermore, one interesting report shows that treatment of hyperuricemia with allopurinol lowers blood pressure in juvenile essential hypertension patients with hyperuricemia. In addition, it is well known that hyperuricemia is closely associated with chronic kidney disease (CKD), is a risk factor for renal insufficiency in general populations, and is a poor prognostic factor of renal function in patients who also have IgA nephropathy. On the other hand, in intervention studies on hyperuricemia, the treatment of hyperuricemia with allopurinol in CKD has resulted in a fall in blood pressure and inhibition of the progression of renal damage. Conversely, the cessation of allopurinol treatment in CKD was followed by a rise in blood pressure and the development of renal damage. Furthermore, the rise of blood pressure and development of renal damage following cessation of allopurinol treatment are only seen in patients not receiving angiotensin converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB). This suggests that the renin angiotensin (RA) system plays an important role in the development of hypertension and renal damage from hyperuricemia.  相似文献   

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《BMJ (Clinical research ed.)》1959,2(5159):1091-1092,1093
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胰岛素抵抗(IR)是许多疾病的独立危险因素。胰岛素抵抗与脂肪代谢紊乱非常密切,研究发现它在脂肪肝的发生、发展过程中起了很大的作用。近年来,越来越多的人已经意识到脂肪肝与胰岛素抵抗之间的密切关系。在胰岛素抵抗与脂肪肝的研究中关于瘦素及瘦素抵抗在胰岛素抵抗及脂肪肝的关系中的作用是研究比较多的,本文主要介绍了胰岛素抵抗、脂肪肝的发生机制及瘦素、瘦素抵抗在其中的催化作用。  相似文献   

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阿尔茨海默病(Alzheimer’s disease, AD)是一种神经退行性疾病,过度磷酸化tau异常聚集形成的神经纤维缠结是其主要病理特征之一。线粒体损伤在AD发病机制中发挥重要作用,是AD的早期病理事件,而其又与tau蛋白密切相关。文中总结了AD中病理性tau蛋白对线粒体动力学、形态、自噬、功能等方面造成的损伤,并展望了从保护线粒体损伤角度研发防治AD药物的可行性。  相似文献   

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大豆生理生态特性与产量的关系(英文)   总被引:11,自引:0,他引:11  
比较研究了 1 970s、1 980s和 1 990s期间不同大豆 (Glycinemax (L .)Merr.)品种的生理生态特性 :光合作用、蒸腾作用、气孔导度、水分利用效率、胞间CO2 浓度和叶片水势 ,分析了各生理生态特性之间以及与产量在不同生育期的关系。研究表明光合速率和产量之间存在显著的相关关系 ,高产大豆同时具有高的气孔导度和水势 ,胞间CO2 浓度则很低 ,特别是在鼓粒期关系更为显著。高产大豆的光合作用在鼓粒期达到最高值 ,光合作用日变化呈双峰曲线。在鼓粒期高产大豆的光合产物大量运往籽粒中 ,对于高产品种和高光效_“源”固然重要 ,而“流”_光合产物的合理运转和分配对产量则更为重要  相似文献   

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Background and aims

The contribution of arterial calcification (AC) in peripheral arterial disease (PAD) and arterial wall compressibility is a matter of debate. Pseudoxanthoma elasticum (PXE), an inherited metabolic disease due to ABCC6 gene mutations, combines elastic fiber fragmentation and calcification in various soft tissues including the arterial wall. Since AC is associated with PAD, a frequent complication of PXE, we sought to determine the role of AC in PAD and arterial wall compressibility in this group of patients.

Methods and Results

Arterial compressibility and patency were determined by ankle-brachial pressure index (ABI) in a cohort of 71 PXE patients (mean age 48±SD 14 yrs, 45 women) and compared to 30 controls without PAD. Lower limb arterial calcification (LLAC) was determined by non-contrast enhanced helicoidal CT-scan. A calcification score (Ca-score) was computed for the femoral, popliteal and sub-popliteal artery segments of both legs. Forty patients with PXE had an ABI<0.90 and none had an ABI>1.40. LLAC increased with age, significantly more in PXE subjects than controls. A negative association was found between LLAC and ABI (r = −0.363, p = 0.002). The LLAC was independently associated with PXE and age, and ABI was not linked to cardiovascular risk factors.

Conclusions

The presence of AC was associated with PAD and PXE without affecting arterial compressibility. PAD in PXE patients is probably due to proximal obstructive lesions developing independently from cardiovascular risk factors.  相似文献   

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In chronic kidney disease (CKD), osteodystrophy and arterial calcification often coexist. However, arterial alterations have not been addressed in CKD unaccompanied by evidence of calcification. We investigated the association of phosphate (P) and calcium (Ca) accumulation in calcification-free aortas with CKD-induced osteodystrophy. Aortic accumulation of magnesium (Mg), an inhibitor of calcification, was also examined. Male mice aged 26?weeks with CKD characterized by hyperparathyroidism and hyperphosphatemia (Nx, n?=?8) and age-matched healthy male mice (shams, n?=?8) were sampled for blood, and thoracic vertebrae and aortas were harvested. Bone structure and chemicals were analyzed by microcomputed tomography and infrared microspectroscopy, respectively, and aortic accumulation of P, Ca, and Mg was evaluated by plasma-atomic emission spectrometry. Volume fractions of cortical and trabecular bones were smaller in Nx than in sham animals (P?<?0.05), attributed to cortical thinning and reduction in trabecular number, respectively. Bone chemicals were not different between the groups. No calcification was found in either group, but P, Ca, and Mg contents were higher in Nx than in shams (P?<?0.05). The mass ratio of Ca/P was lower in Nx than in shams (P?<?0.05), but that of Mg/Ca and Mg/P was not different between the groups. Aortic P and Ca contents were inversely correlated with the volume fraction of cortical bone (P?<?0.05). In conclusion, the relationship of osteodystrophy with aortic P and Ca accumulation suggests the existence of a bone-vascular axis, even in calcification-free arteries in CKD. The preservation of ratios of Mg/Ca and Mg/P despite CKD development might contribute to calcification resistance.  相似文献   

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高尔基体是一个非常重要的细胞器,最近研究表明,它除了蛋白加工外,还能参与细胞分化、细胞间信号传导和细胞凋亡,其功能障碍也许和疾病的发生、发展有着某种联系。随着蛋白组学技术的发展,使得筛选新的肿瘤标志物成为可能,其中高尔基体蛋白73(GP73)被认为是最值得期待的血清标志物之一,尤其是早期肝癌的血清标志物。本文对近年来有关GP73结构、表达分布以与及消化系统疾病的研究进展进行综述。  相似文献   

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The mutations in human glucosylceramidase lead to Gaucher disease, which is the most prevalent lysosomal storage disease. So far 153 point mutations have been recorded in human glucosylceramidase, resulting in a wide variability in clinical presentations. In this study, we use the amino-acid distribution probability to quantify each mutation, and use the cross-impact analysis with Bayes’ law to build a quantitative relationship between mutated primary structure of human glucosylceramidase and status of Gaucher disease. The results demonstrate that we can build a quantitative relationship between changed structure and changed function of protein, which is useful for understanding the genotype–phenotype relationship of disease.  相似文献   

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阿尔次海默病易溶型胞浆tau和难溶型双螺旋丝中的tau均被异常磷酸化和异常糖基化修饰。异常修饰的tau丧失其促微管组装生,用不同蛋白磷酸酯酶对难溶型双螺旋丝中的tau磷酸化处理后可不同程度恢复其促微管组装生物学活性。  相似文献   

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