Stathmin levels in growth plate chondrocytes are modulated by vitamin D3 metabolites and transforming growth factor-beta1 and are associated with proliferation

Stathmin is a highly conserved, phosphorylated cytosolic protein that is found at decreased levels in all cells as they become more terminally differentiated, or when they decrease in their rate of proliferation. This study examined the hypothesis that stathmin levels in growth plate chondrocytes decreases as endochondral maturation increases. To test this hypothesis, we used a costochondral growth plate chondrocyte cell culture model. Cells derived from the resting zone (RC) express twice as much stathmin mRNA in culture and have twice as much stathmin protein as cells derived from the post proliferative growth zone ([GC];prehypertrophic and upper hypertrophic cell zones). Stathmin levels in vivo were assessed by immunohistochemistry. To assess the effects of agents that modulate proliferation and differentiation, RC and GC chondrocytes were cultured in the presence of 10⁻¹⁰ to 10⁻⁸ M 1α,25-(OH)₂D₃, which regulates proliferation in both cell types but affects differentiation of only GC cells, or 10⁻⁹ to 10⁻⁷ M 24R,25-(OH)₂D₃, which regulates differentiation and maturation of RC cells, but decreases proliferation of GC cells. In addition, RC cells were treated with 0.44 or 0.88 ng/mL of recombinant human transforming growth factor β1 (rhTGF-β1), which stimulates proliferation of RC cells and regulates proteoglycan production, but not alkaline phosphatase activity. Stathmin protein levels were determined using quantitative immunoblots, with recombinant human stathmin as a standard. The results show that stathmin levels are associated with proliferation. Proliferating chondrocytes in vivo exhibited higher levels of immunoreactive stathmin than either RC or GC cells in the growth plate. In culture, 1α,25-(OH)₂D₃ caused a dose-dependent de-crease in stathmin in RC and GC cells within 24 h. 24 R, 25-(OH)₂D₃ also reduced stathmin levels in GC cells within 24 h but only affected RC cells after prolonged exposures (96 h), at which time RC cells express a GC-like phenotype. rhTGF-β1 caused an increase in stathmin levels in RC cells. Stathmin levels are sensitive to protein kinase C (PKC) in other cells. Inhibition of PKC with chelerythrine had no effect on the response of RC cells to 1α,25-(OH)₂D₃ but it blocked the effect of rhTGF-β1, indicating that decreases in stathmin by vitamin D₃ metabolites may not be modulated by PKC, whereas increases in stathmin via rhTGF-β1 may be regulated via a PKC-dependent mechanism. These results support the hypothesis that constitutively expressed levels of stathmin are related to cell maturation state and that they are modulated by factors that regulate proliferation.     

1,25-(OH)2D3对糖尿病大鼠肾脏Nephrin蛋白表达的影响

目的探讨1,25-(OH)2D3对糖尿病(DM)大鼠肾脏Nephrin蛋白表达的影响。方法Wistar大鼠分为对照组、DM组、1,25-(OH)2D3组。建立糖尿病大鼠模型,实验12周末观察各组血尿、蛋白尿、肾组织光镜电镜、免疫组织化学,采用反转录聚合酶链反应(RT-PCR)检测其肾皮质NephrinmRNA及蛋白的表达。结果与对照组及1,25-(OH)2D3组相比,DM组大鼠尿红细胞及尿蛋白排泄明显增多,肾小球细胞数亦增加(P<0.01,0.05),NephrinmRNA及蛋白质表达明显下调(Pa<0.01)。1,25-(OH)2D3组肾小球细胞数、NephrinmRNA及蛋白质表达与对照组相比无统计学差异(Pa>0.05)。结论1,25-(OH)2D3可减轻血尿、蛋白尿,上调NephrinmRNA及蛋白质的表达而有肾保护作用。     

Idiopathic rapidly progressive glomerulonephritis with C3 nephritic factor and hypocomplementemia.

A 7-year-old boy with mild renal failure and signs and symptoms of acute poststreptococcal glomerulonephritis including severe hypocomplementemia had, by renal biopsy, numerous crescents but no deposits in the glomerular capillary loops. Instead, deposits identical in location and composition to those described for children with idiopathic rapidly progressive glomerulonephritis were present. The severe hypocomplementemia was found to be due to high levels of C3 nephritic factor; niether nephritic factor nor hypocomplementemia has been reported in rapidly progressive glomerulonephritis of the idiopathic type. Following prompt therapy with methylprednisolone intravenously, serologic abnormalities disappeared and renal function greatly improved, but a later biopsy showed 50% of the glomeruli obliterated by scarring. The case is of importance not only in indicating that severe hypocomplementemia does not rule out idiopathic rapidly progressive glomerulonephritis but also in adding to the list of diseases in which nephritic factor can be found.     

The effect of a low continuous positive airway pressure on the reflex control of respiration in the preterm infant

The airway occlusion technique was used to measure the strength of the Hering-Breuer inflation reflex before and during the administration of low pressure CPAP. In five of 12 preterm infants studied in the first two weeks of life, CPAP did not alter the inflation reflex. In the other seven premature infants, shortened rather than lengthened inspiratory efforts were observed on occlusion 32 times of CPAP but only twice on CPAP. In seven term infants at 1 to 2.5 hours of age this shortening was noted only twice in 58 occlusions. In the preterm infants exhibiting short responses, the peak inspiratory pressure generated in response to occlusion rose on CPAP from 3.4 to 7.1 cm H2O (p less than 0.005), while respiratory rate fell from 61 to 49 breaths/minute (p less than 0.025). This data suggests that CPAP enhances these infants' ability to adjust to increased respiratory loads, possibly by the elimination of a Hering-Breuer deflation reflex.     

High 1,25-Dihydroxyvitamin D and Low 25-Hydroxyvitamin D Concentrations in Plasma in Patients Receiving Antiepileptic Drugs

Abstract: Plasma 25-hydroxyvitamin D (25-OH D), 1,25-dihydroxy vitamin D (1,25-(OH)₂ D) and parathyroid hormone (PTH) concentrations were determined in 30 outpatients receiving various antiepileptic drugs (AED). None of the patients exhibited high plasma PTH levels. The plasma 1,25-(OH) ₂ D levels were normal or high, a'though in a third of the patients the 25-OH D levels were reduced. There was a corre'ation between the 25-OH D and serum calcium levels. These findings suggest that the low plasma concentrations of 25-OH D, not 1,25-(OH)₂ D, might play an important part in the occurrence of AED-induced disturbances of bone metabolism.     

从三元混合溶剂中回收二氯甲烷的试验

采用0．15g/ml醋酸钾乙二醇溶液作为分离剂，用加盐萃取精馏法对某抗生素原药合成所产生的二氯甲烷－甲醇－水三元体系的母液进行分离，找到了合适的试验条件，并得到纯度为99．6％的二氯甲烷。结果表明醋酸钾乙二醇溶液是一种来源方便、价格便宜、易于回收、分离效果较理想的加盐萃取剂。     

Older Mayan residents of the western highlands of Guatemala lack sufficient levels of vitamin D

Vitamin D (VitD) levels in older Mayans are currently unknown. Geographic factors, for example, residences in areas receiving ample sunlight at high altitudes and latitudes near the equator, would favor optimum VitD levels, whereas demographic factors, for example, darker skin pigmentation, clothing practices, and older age, would favor low 25-hydroxy-vitamin D, or 25(OH)D, levels. Conjecturing that demographic factors affecting VitD status might outweigh geographic factors in this population, we hypothesized that older Mayans have suboptimal values of 25(OH)D. We also hypothesized that older Mayans in rural areas would have higher VitD levels than would their urban counterparts. Blood samples were collected from 108 healthy older Mayans (mean age, 69 years) from urban (n = 84, 50% male) and rural settings (n = 24, 50% male) during the summer of 2008 in the highlands of Quetzaltenango, Guatemala. We assessed 25(OH)D concentrations by radioimmunoassay in a US-based laboratory. Mean (SD) serum 25(OH)D values were 53.3 (15.0) nmol/L, and lower 25(OH)D values were associated with increasing age (r = −0.58, P = .004). Of all subjects, 3.7% (n = 4) maintained an optimal status of 25(OH)D (>80 nmol/L), 50% (n = 54) had values between 50 and 80 nmol/L, and 46.3% (n = 50) had levels less than 50 nmol/L. Urban subjects had nonsignificantly higher 25(OH)D values (55.0 ± 15.3 nmol/L) than did rural subjects (47.4 ± 12.4 nmol/L, P = .228). Men had significantly higher values (58.2 ± 16.5 nmol/L) than did women (48.4 ± 11.6 nmol/L, P = .001). We conclude that despite residing in an optimal geographic location to receive adequate sunlight exposure, most older Guatemalan Mayans in Quetzaltenango have suboptimal levels of VitD.