Osteocalcin serum levels in patients following renal transplantation

Summary Osteocalcin serum levels reflect bone turnover. In renal insufficiency secondary hyperparathyroidism and reduced renal clearance might be responsible for elevated serum levels of osteocalcin. Renal transplantation might improve renal osteodystrophy and therefore could influence osteocalcin serum levels.We determined the influence of renal transplantation on osteocalcin levels in 37 consecutive patients (25m/12f) by RIA. Blood samples were collected prior to, 3 days, 28 days, 6 months and 12 months after renal transplantation.Prior to renal transplantation osteocalcin levels were significantly elevated (x±s: 23.4±12.8 ng/ml) compared to healthy volunteers (4.1±1.4 ng/ml). Following renal transplantation osteocalcin decreased significantly (9.4±8.9 ng/ml) 3 days and (7.1±7.8 ng/ml) 28 days. However, 6 and 12 months following renal transplantation the mean osteocalcin level increased again (8.3±5.7 ng/ml, 12.1±15.4 ng/ml). At 6 months 11 and at 12 months only 6 of 37 patients had osteocalcin levels in the normal range. 12 months following renal transplantation 21 out of 37 patients with elevated osteocalcin levels had parathyroid hormone levels above the normal range. Additionally to increased osteocalcin levels patients prior to renal transplantation had elevated alkaline phosphatase. Alkaline phosphatase had following renal transplantation a similar pattern as osteocalcin with initial decrease and secondary increase 6 and 12 months after renal transplantation. Parathyroid hormone was elevated in all patients before renal transplantation. Following renal transplantation mean parathyroid hormone levels fell significantly, however remained above normal range in 57% of these 37 patients. Osteocalcin serum levels correlated positively with alkaline phosphatase (rs=0.43–0.62;p<0.011) and parathyroid hormone (0.3–0.66p<0.07). This correlation of osteocalcin with alkaline phosphatase and parathyroid hormone prior to and after renal transplantation suggests that osteocalcin may be a confirmative parameter in renal osteodystrophy in patients on chronic intermittent hemodialysis and following renal transplantation.Abbreviations RIA radio immuno assay - OC Osteocalcin - rtx renal transplantation - GLA gammacarboxyglutamic acid - PTH parathyroid hormone - AP alkaline phosphatase - GLA gamma-carboxyglutamic acid     

Bone changes in hemodialyzed uremic subjects

Summary Needle biopsies from the iliac crest of 40 uremic patients treated with hemodialysis have been compared by light and electron microscopy. The most obvious bone changes were represented by an increased amount of osteoid tissue (osteomalacic changes) and by enhanced bone resorption. The osteomalacic changes were chiefly characterized by the presence of thick osteoid borders whose collagen fibrils were often completely uncalcified. In a few cases, small roundish aggregates of crystals were irregularly present through the osteoid matrix; some of them were closely related to roundish, electron-dense bodies surrounded by a membrane.The increased rate of bone resorption, which was often comparable to that which occurs in the most severe cases of plimary hyperparathyroidism, was due to both osteoclastic activity and osteocytic osteolysis. Electron microscopy showed that the enlargement and irregularity of the osteocytic lacunae were not always due to osteocytic osteolysis; the same effect might be due to defective calcification of the lacunar wall. The advantages of comparing the same specimens under the light and electron microscopes are discussed.Supported in part by the Italian National Research Council.The authors are very grateful to Miss Giuliana Silvestrini and Mr. Lucio Virgilii for their expert technical assistance.     

Trabecular bone morphometry in beagles with chronic renal failure

Summary A morphometric study was performed on undecalcified sections of trabecular bone from the ribs of adult dogs that were controls (n=8), or had various degrees of renal failure as a result of perinatal irradiation (n=16). In a group identified as markedly uremic there was an increase in the proportion of surface with osteoid seams (P<0.01), osteoblasts (P<0.01) and osteoclastic resorption (P<0.01) as well as the % osteoid volume (P<0.01). Aside from a decrease in the % trabecular bone which was of unclear significance, the results agree well with those of similar studies in man. Within this group, 6 of the samples had a histologic pattern that was principally that of hyperparathyroidism and in the remaining 2 there was evidence of a mineralization defect and osteomalacic changes. These 2 dogs had the poorest renal function and one that had been biopsied 5 months earlier, when its renal function was less impaired, had had a hyperparathyroid pattern.     

Ultrasonography methods in the diagnosis of renal osteodystrophy

Bone disease, i.e. renal osteodystrophy, is commonly seen in patients with chronic renal failure. It encompasses all the disorders of mineral and bone metabolism associated with chronic renal insufficiency, i.e. secondary hyperparathyroidism, retention and accumulation of beta 2 microglobulin and aluminum. The most frequent cause of renal osteodystrophy is secondary hyperthyroidism, with a consequence of high turnover bone disease. Secondary hyperparathyroidism, i.e. increased parathyroid hormone (PTH) secretion and parathyroid gland hyperplasia, develops early in the course of chronic renal insufficiency. Hypocalcemia, phosphate retention and deficiency of calcitriol stimulate PTH synthesis and secretion and parathyroid cell proliferation, i.e. hyperplasia. Parathyroid cell proliferation is initially polyclonal (diffuse hyperplasia), and later it is monoclonal or multiclonal (nodular hyperplasia). Calcitriol receptors as well as calcium-sensing receptors are significantly reduced in parathyroid glands in nodular hyperplasia. Patients with such parathyroid gland hyperplasia are often resistant to vitamin D therapy. A specific form of bone disease is beta 2 amyloidosis. Destructive arthropathy, cystic changes and carpal tunnel syndrome are clinical manifestations of dialysis-related amyloidosis, which is one of the major complications in patients on longterm hemodialysis. Aluminum intoxication leads to the low turnover bone disease and consequential osteomalacia or aplastic bone lesions, the cause of which has not yet been fully clarified. Ultrasound can be a useful, economical and noninvasive method in the evaluation of renal osteodystrophy. Ultrasound waves are very important for noninvasive imaging of soft tissue, especially parathyroid glands, pathologic changes of the joints, and for detection of metastatic calcifications. They are also useful in the evaluation of skeletal status in dialysis patients. Ultrasound waves of a frequency above the limit of human hearing are used in the morphological diagnosis of parathyroid gland. Today, because of its simplicity and non-invasiveness, it is a generally accepted method for the detection of enlarged parathyroid gland in patients with secondary hyperparathyroidism, for the monitoring of pathologic changes, and for making decisions on the method of treatment based on the size and number of parathyroid glands. Ultrasound can distinguish nodal from diffuse parathyroid hyperplasia. Under ultrasound guidance it is possible to perform fine needle aspiration biopsy, to confirm ultrasound findings, and percutaneous inactivation of parathyroid gland (PEI) with alcohol. Ultrasound is useful in the diagnosis of pathologic changes of the musculoskeletal system in patients with beta 2 amyloidosis, to assess the process of its spread, especially in the shoulder joint where the changes are most pronounced (rotator cuff thickness, amyloid deposits as hyperechogenic pads, and detection of fluid in the joint), but it can also be used to examine other joints as well as soft tissue in which metastatic calcifications may occur. Standard ultrasound equipment (pulse-echo) and linear probe of 5-13 MHz are used, also serving for ultrasound examination of the neck, joints and soft tissue. Quantitative bone ultrasonometry is based on different physical characteristics of the ultrasound including: transmission, Speed Of Sound (SOS) in meters/sec and Broad Band Attenuation (BUA) in dB/MHz, and different concepts of the apparatus. These parameters depend on the strength and architecture of the bones and describe better the changes in bone structure in dialysis patients by calculation of the Stiffness Index (QUI), better than the standard bone densitometry by dual-energy x-ray absorptiometry, which only measures bone density. Combined ultrasound measurement of the bone in several locations may be successful in monitoring dialysis patients.     

The ultrastructure of bone cells and bone matrix in human primary hyperparathyroidism

Summary An electron microscope investigation has been carried out on needle biopsies of the iliac crest of 8 patients suffering from primary hyperparathyroidism.A marked increase in bone resorption was the most conspicuous finding. It was due both to increased osteoclastic activity and to periosteocytic osteolysis. The osteoclasts had a more strongly developed brush border and contained more cytoplasmic vacuoles than those in controls. Many osteocytes were found within enlarged, irregular lacunae, and were surrounded by a space containing amorphous, granular and filamentous material. Their mitochondria were sometimes calcified. Osteoblasts were more active than in controls as shown by the developed rough ergastoplasmic cysternae and thick osteoid borders found near some of them. The osteoid tissue, however, was uncalcified; ultrastructurally, lack of the calcification front and incomplete matrix calcification were demonstrable. Mast cells, and osteoclast- and macrophage-like giant cells were often found in the fibrotic marrow spaces.These results confirm that both the resorption and the formation of bone are stimulated in hyperparathyroidism. The calcification process is delayed and often remains incomplete.     

The localization of aluminium and other elements inbone tissue of a case of renal osteodystrophy with an associated dialysis encephalopathy syndrome

Bone tissue from a patient with chronic renal failure and a dialysis encephalopathy syndrome has been studied by histological and histochemical means, by flame emission spectroscopy and by electron probe X-ray microanalysis. There was significant renal osteodystrophy manifest as an osteomalacia. Emission spectroscopy showed the presence of iron (Fe), aluminium (Al), silicon (Si), zinc (Zn), strontium (Sr), lead (Pb) and copper (Cu) in the concentration range 100–1000 parts per million (ppm). Electron probe X-ray microanalysis showed focal concentrations of Fe and Si in the marrow tissue only, whereas Al was localized to the calcification front zones at the junction of osteoid and mineralized tissue of both trabecular and cortical bone. It is concluded that the presence of Al at these sites could interfere with the mineralization process and significantly contribute to the pathogenesis of haemodialysis-related osteomalacia and that it is unlikely that the other elements detected are significant in this regard.     

25-hydroxycholecalciferol in the treatment of renal osteodystrophy in haemodialysed patients

The effects of 25-OHD3 on renal osteodystrophy have been studied in 6 patients on maintenance haemodialysis. Administration of 25-OHD3, 50 microgram/day, did not improve biochemical data and intestinal absorption of calcium. With a dose of 100 microgram/day in all patients an increase in blood calcium levels eventually reaching hypercalcemic values was observed. In two cases a fall in alkaline phosphatase toward normal values was noted. In the same cases the treatment-induced hyperphosphatemia, uncontrolled by AI(OH)3 supplementation and similarly high iPTH levels were observed. In two cases repeated bone biopsy following 8 months treatment and not show substantial improvement of bone lesions. In one case addition of 1,25-(OH)2D3 to the treatment with 25-OHD3 led to a more rapid improvement in biochemical parameters and iPTH serum levels. Doses of 25-OHD3 capable to correct blood calcium levels and intestinal absorption of calcium, may have minimal benefit on the osteitis fibrosa component of the bone lesion.     

Tubular ultrastructure in rejected human renal allografts

Twenty percutaneous renal transplant biopsies and 20 removed allografts were investigated ultrastructurally. Most of the detected alterations were of a degenerative or regenerative nature and not specific of rejection. The most interesting phenomenon was the tubulitis, namely, the migration of the interstitial inflammatory cells (IC) through the tubular basement membrane (BM) and the invasion of the tubular epithelium in this way. Tubular epithelial cells (TEC) in the vicinity of IC were often necrotic. The composition of cells invading the tubules corresponded to those infiltrating the interstitium. The distal tubule was more frequently infiltrated than the proximal tubule. The TEC were always in very close contact with the BM. The invading IC were in direct contact with the inner surface of the BM only while passing through it. IC that passed the BM were immediately separated from it by a thin epithelial layer. The tubular ultrastructural changes did not reveal substantial differences between the various rejection types, except for the pronounced thickening and lamellation of the BM in chronic rejection.     

Immunohistochemical study of nodular hyperplastic parathyroid glands in patients with secondary hyperparathyroidism

Summary Thirty-seven nodular hyperplastic parathyroid glands obtained by subtotal parathyroidectomy from 11 haemodialysed patients with secondary hyperparathyroidism were examined both pathologically and immunohistochemically. Four consecutive sections of the largest section-surface of each gland were subject to 4 different stains (haematoxyline-eosin, Grimelius, and the immunohistochemical stains for parathyroid hormone and chromogranin A) for comparison of each nodule.It was found that the major part of each nodule consisted of a single cell type with a single pattern of cells. These reacted uniformly to each stain. The mechanism involved in the storage and secretion of the secretory granule appeared to be regulated at the nodule and not at the cell level. The results suggest that the nodules may come from a monoclonal proliferation of a single parathyroid cell.Our present light microscopic immunohistochemical study, failed to demonstrate completely identical immunoreactive positivity of each nodule or each parathyroid cell to PTH. Chromogranin A or secretory protein-I did not indicate the coexistence of PTH and SP-I in the same secretory granule, which was in good agreement with the electron microscopic immunocytochemical study of Arps using bovine parathyroid glands. Our present study, however, provides good evidence that chromogranin A positivity is demonstrable in the human parathyroid gland outside the adrenal medulla and sympathetic nerves.     

Bone biopsy as a diagnostic tool in the assessment of renal osteodystrophy

When renal disease develops, mineral and vitamin D homeostasis is disrupted, resulting in diverse modifications in bone cells, bone structure and the rate of bone turnover. In end stage renal failure (ESRF) when patients require chronic maintenance dialysis, nearly all of them have abnormal bone histology known as renal osteodystrophy (ROD). Moreover, survival rates of patients on dialysis have increased because of therapeutic improvement and the resultant increase in duration of dialysis has led to a further rise in renal osteodystrophy. Because metabolic bone disease can produce fractures, bone pain, and deformities late in the course of the disease, prevention and early treatment are essential. Serum PTH and various bone markers are commonly used to assess bone changes in ESRF patients, but the diagnosis of underlying bone disease is still rather uncertain. To date, bone biopsy is the most powerful and informative diagnostic tool to provide precise information on the type and severity of renal osteodystrophy, and on the presence and amount of aluminum and strontium deposited in the bone. Bone biopsy is not only useful in clinical settings but also in research to assess the effects of therapies on bone. Although considered an invasive procedure, bone biopsy has been proven to be safe and free from major complications, but the operator's experience and skill is important in further minimizing morbidity. Alternatives to bone biopsy continue to be sought, but the non-invasive bone markers have not been proven to be sufficient in diagnostic performance related to bone turnover, mineralization process and bone cell abnormality. Hence, transiliac bone biopsy remains the gold standard for the diagnosis of renal osteodystrophy.     

Increased whole blood chemiluminescence in patients with chronic renal failure independent of hemodialysis treatment

Introduction: The luminol-enhanced whole blood chemiluminescence (LBCL) assay is a rapid assay for the measurement of reactive oxygen species (ROS) generation by circulating phagocytes. This study’s aim was to determine if patients on maintenance hemodialysis (HD) and non-dialyzed patients with chronic renal failure (CRF) have altered LBCL and if dialysis itself affects ROS production in the blood. Materials and Methods: Twenty-six HD patients, 11 non-dialyzed patients with CRF, and 20 gender- and age-matched healthy controls were studied. Resting (rCl) and 2 × 10⁻⁵ M n-formyl-methionyl-leucyl-phenylalanine-stimulated LBCL (peak chemiluminescence: pCl, total light emission after agonist addition: tCl) calculated per 10⁴ phagocytes present in the 3-μl blood samples were measured with a Bio-Orbit^? 1251 luminometer at 37°C for 11 min. Results: Prior to the HD session, median rCL, pCL, and tCL were 1.5, 3.0, and 2.8 times higher in HD patients than in healthy controls (p<0.01) and tended to increase at the end of the session. Significant increases in tCl were observed at 30 min and 240 min (end) of HD (1023.5 vs. 1810.6 vs. 2006.8 arbitrary units × s/10⁴ phagocytes, n=9, p<0.05). Median pCl and tCl were 5.0 and 4.3 times higher in non-dialyzed patients with CRF than in healthy controls (p<0.001). However, no significant differences were found between pre- and post-HD LBCL of HD patients and the LBCL of non-dialyzed patients with renal failure. Conclusions: Blood from patients with renal failure generates elevated amounts of oxidants independently of HD treatment. This may add to the understanding of the nature of oxidative stress and suggests the need of anti-oxidant treatment in these patients.     

高通量血液透析与常规血液透析治疗后 慢性尿毒症患者的指标分析

目的 探讨高通量血液透析与常规血液透析治疗慢性尿毒症患者的临床疗效。方法 选取2015年7月~2017年10月我院收治的慢性尿毒症患者55例为研究对象,按数字随机分为观察组27例和对照组28例,对照组给予常规血液透析,观察组给予高通量血液透析,对比两组治疗后β2-MG、Cer、Urea、KT/V各指标变化。结果 两组透析后β2-MG指标变化低于透析前,差异有统计学意义（P＜0.05）,观察组透析后β2-MG指标变化优于对照组,差异有统计学意义（P＜0.05）,两组透析前后各项指标均下降,差异有统计学意义（P＜0.05）,观察组透析后各项指标变化和对照组对比,差异无统计学意义（P＞0.05）,两组透析前后Cer、Urea等指标变化低于透析前,差异有统计学意义（P＜0.05）,观察组透析后Cer、Urea和KT/V等指标和对照组对比,差异无统计学意义（P＞0.05）。结论 将高通量透析用于慢性尿毒症患者的治疗中可以维持患者电解质平衡,促进患者身体恢复,改善患者症状。     

内毒素血症犬肾功能和超微结构的变化

我们研究了内毒素对狗肾脏功能和超微结构的影响。实验结果表明,注射后肾功能立即减退。在注射后4小时,血尿素氮、肌酐与对照组相比明显增高,尿渗透压尿钠,尿/血渗透压比值均明显降低。在注射内毒素后1、2、8小时也出现类似变化。电镜观察肾小球基本正常。近曲小管变化有局部的刷状缘微绒毛歪曲、部分脱落入管腔。腺粒体肿胀并伴小块雾状致密影。近曲小管细胞基底和侧突减少、变平。     

西那卡塞对维持性血液透析继发性甲状旁腺功能亢进患者FGF-23的影响

目的 研究西那卡塞对维持性血液透析继发性甲状旁腺功能亢进患者FGF-23的影响。方法 选取2015年1月~2016年10月在天津市第一中心医院血液净化中心行维持性血液透析治疗合并继发性甲状旁腺功能亢进的患者,按入院顺序随机分为观察组及对照组,对照组40例,给予骨化三醇治疗,观察组39例,给予对照组患者相同的骨化三醇治疗的基础上,再加用盐酸西那卡塞片,两组均连续治疗3个月。监测两组治疗前后的尿素氮、血肌酐、KT/V、血清钙、血清磷、碱性磷酸酶、钙磷乘积、全段甲状旁腺激素 (iPTH)及血清FGF-23。结果 治疗后,两组患者的BUN、SCr和Kt/V 较治疗前,差异无统计学意义（P＞0.05）;血清钙观察组治疗后低于对照组（P＜0.05）,对照组治疗前后,差异无统计学意义（P＞0.05）;两组血清磷、ALP、钙磷乘积、iPTH、FGF-23治疗后降低,且治疗后观察组优于对照组,差异有统计学意义 (P<0.05)。结论 西那卡塞对于维持性血液透析合并继发性甲状旁腺功能亢进的患者能够降低甲状旁腺激素及FGF-23水平,缩小甲状旁腺体积。     

Experimental osteodystrophy of chronic renal failure induced by aluminum- and ferric-nitrilotriacetate in Wistar rats

The aluminum (Al) and iron (Fe) chelate complexes of nitrilotriacetate (NTA) cause renal insufficiency when they are administered intraperitoneally to rats. Their effects on bone metabolism were studied in 4 week old Wistar rats. Daily intraperitoneal administration of Al-NTA (3 mg Al/kg for 11 weeks) induced osteomalacia, impaired bone growth, decreased bone mineral density, lower serum PTH levels than normal as well as renal insufficiency. Al staining showed diffuse deposition in the trabecula and a strong linear band of aluminum deposited at the mineralization front and along the cement line. The osteoid seen markedly within the trabecula was probably the decalcified portion of the bone, the calcium apatite of which was defectively fabricated because of diffuse Al deposition in the trabecula. Al deposition along the cement line would make it much more susceptible to external shear stress than normal. Although daily intraperitoneal administration of Fe-NTA (6 mg Fe/kg for 11 weeks) caused impaired bone growth, decreased bone mineral content and renal insufficiency, the osteoid volume did not increase. Fe staining showed that Fe was deposited diffusely in the cytoplasm of osteoblasts. The results of this study demonstrated that during renal insufficiency, different minerals exhibi different modes of action on bone metabolism, and that AI-NTA is useful for experimental animal models of Al-induced osteomalacia in renal insufficiency.