Effect of proinflammatory cytokines (IL-6, TNF-alpha, IL-1beta) on hemodynamic performance during orthotopic liver transplantation.

BACKGROUND: Proinflammatory cytokines (IL-6, IL-1beta, TNF-alpha) released during liver transplantation may affect hemodynamic stability. The aim of the present study was to analyze the association between IL-6, TNF-alpha, and IL-1beta and systemic vascular resistance during the phases of liver transplantation. MATERIAL AND METHODS: The proinflammatory cytokines IL-6, IL-1beta, and TNF-alpha were analyzed in the blood of 20 consecutive patients who underwent transplantation. Blood samples were drawn from the pulmonary artery at serial times during surgery. Hemodynamic parameters were determined using a cardiac output monitor. Correlations between parameters were analyzed using the Spearman's rho and Kendall's tau-b methods. RESULTS: Both in the vena cava and the pulmonary artery, significant association was observed between basal values of IL-6 during hepatectomy and systemic vascular resistance during the phases of liver transplantation: hepatectomy phase (r=.76, P=.02), anhepatic phase (r=.78, P=.03) and reperfusion phase (r=.87, P=.005). CONCLUSIONS: Basal values of IL-6 may be considered a prognostic factor for hemodynamic performance during the phases of liver transplantation.

Association between anatomopathologic graft disorders during reperfusion and vena cava sIL-2r in orthotopic liver transplantation.

UNLABELLED: Graft ischemia-reperfusion injury during orthotopic liver transplantation (OLT) is associated with anatomic and pathologic disorders in the graft, which may cause initial dysfunction. The object of this paper was to evaluate sIL-2r as an indicator of liver damage during graft reperfusion. MATERIAL AND METHODS: Blood samples were drawn from 20 consecutive patients who required OLT secondary to chronic end-stage insufficiency various sites (portal vein, vena cava, pulmonary artery) and during different surgical phases. Following centrifugation and storage at -70 degrees C, sIL-2r was quantitated by chemiluminescence (Immulite, EURO/DPC). In addition biopsies were graded from 0 to III according to the anatomic and pathologic findings. Base excess and ammonia were measured to evaluate the function of the new liver. STATISTICAL ANALYSES: Parameter associations were explored using Spearman's Rho and Kendall's Tau-b methods. RESULTS: There was a correlation between the degree of graft preservation and sIL-2R both during vena cava reperfusion (r=.0591, P=.05) and for the initial 2 hours after reperfusion (r=0.61, P=.062). CONCLUSION: sIL-2r levels drawn from the vena cava after graft reperfusion are associated with its degree of injury.

Mineral metabolism in healthy geriatric dogs.

To study mineral metabolism in geriatric dogs, parathyroid hormone, calcitriol, ionised calcium, phosphorus, blood urea nitrogen and creatinine were evaluated in 35 geriatric dogs (> 10 years) and in 20 young adult dogs (2-5 years). Parathyroid hormone levels were within the normal range in both groups, but values (mean +/- SEM) were greater in the old dogs (34.8 +/- 3.6 vs 21.2 +/- 2.3 pg ml(-1), P=0.005). Calcitriol and ionised calcium were similar in the two groups, and the values for both parameters were within the normal reference range. Plasma phosphorus levels were in the normal range in both groups but tended to be greater in the older dogs (P=0.09). While blood urea nitrogen was similar in the two groups, creatinine levels (mean +/- SEM) were higher in the young dogs (82.2 +/- 3.5 vs 101.7 +/- 4.4 micromol litre(-1)). Even when the dogs were matched for weight, plasma creatinine concentration was still greater in the younger dogs. In conclusion, an increase in parathyroid hormone without changes in calcium, phosphorus and calcitriol has been identified in geriatric dogs.

The effect of a high phosphorus diet on the parathyroid cell cycle.

High extracellular phosphorus directly increases parathyroid hormone (PTH) secretion and gene transcription. The present study evaluates the effect of high phosphorus diet on the parathyroid cell cycle in rats with normal renal function. Rats were divided into two groups, receiving either a high phosphorus diet (HPD, P=1.2%) or a normal phosphorus diet (NPD, P=0.6%). The dietary calcium content was 0.6% in both diets. Rats were pair fed and sacrificed on days 0, 1, 5, 10 and 15 after initiation of the diet. The parathyroid glands were removed and parathyroid cells dispersed for evaluation of cell cycle and apoptosis by flow cytometry. Serum calcium, phosphorus, PTH and calcitriol were measured. As compared with NPD, the ingestion of a HPD resulted in an increased number of cells in the S phase of the cell cycle from day 1 to 10 (1.2+/-0.09% vs 0.6+/-0.04% for day 1, 1.2+/-0.11% vs 0.6+/-0.06% for day 5 and 1.0+/-0.09% vs 0.5+/-0.04% for day 10, P<0.01). By day 15, the percentage of cells in the S phase in NPD and HPD were not different. In the rats fed the HPD, serum PTH increased significantly from day 5 through 15 (P<0.01). Parathyroid cell apoptosis was minimal and unaffected by the diet. At day 15, the parathyroid gland size in HPD was increased by 27% as compared with NPD (P<0.05). This increase should be attributed to cell proliferation since parathyroid cell size remained unchanged. Serum calcitriol and calcium were not significantly different in the two groups. In HPD, an increase in serum phosphorus was observed only on day 1. The results show that an HPD results in the stimulation of the parathyroid cell cycle independently of changes in calcium and calcitriol.

Parathyroid function in long-term renal transplant patients: importance of pre-transplant PTH concentrations.

Lack of resolution of hyperparathyroidism after long-term renal transplantation is common. The relative roles of the graft function attained and the degree of pre-transplant hyperparathyroidism have not been established. Intact parathyroid hormone (iPTH) and several clinical parameters were studied before and 68.6+/-26.8 months (range: 30-124) after renal transplantation in 62 patients (20 females/42 males) with good renal function (creatinine <2 mg/dl). iPTH decreased from 214+/-229 pre-transplantation to 116+/-70 pg/ml post-transplantation (P<0.01). However, only 22.6% of patients had PTH concentrations in the normal range, and values greater than twice the upper normal limit were not uncommon (27.4%). Of the many variables analysed, creatinine (r=0.43; P=0.001) and pre-transplant PTH (r=0.31; P=0.02) significantly correlated with post-transplant PTH. After selecting patients with serum creatinine <1.5 mg/dl (n=46), pre-transplant PTH emerged as the more important predictor of post-transplant PTH (r=0.58; P<0.0001). After controlling for creatinine, the partial correlation was r=0.53, P<0.0001. We concluded that spontaneous resolution of hyperparathyroidism after renal transplantation is uncommon. In addition, the magnitude of pre-transplant hyperparathyroidism and the renal function determine the long-term post-transplant parathyroid function.

Evidence for adaptation of the entire PTH-calcium curve to sustained changes in the serum calcium in haemodialysis patients.

BACKGROUND: Based on in vitro studies, the set point of calcium has often been considered to represent an intrinsic property of parathyroid gland function. However, in the dialysis patient, the serum calcium does not consistently reflect the magnitude of hyperparathyroidism; in addition, little information is available on whether the PTH-calcium curve is modified by sustained changes in the serum calcium. The present study in haemodialysis patients was designed to evaluate whether the set point of calcium and the dynamics of PTH secretion were modified by sustained changes in the serum calcium. METHODS: To accomplish the goal of the study and obtain a wide range of changes in the serum calcium, haemodialysis patients were dialysed with either a 1.75 mM (group I) or a 1.25 mM (group II) calcium dialysate for 2 weeks, and were then changed to a 1.25 mM (group I) or a 1.75 mM (group II) calcium dialysate for an additional 2 weeks. At the end of the first and second 2-week periods, low and high calcium studies were performed to obtain PTH-calcium curves. RESULTS: In group I, the serum ionized calcium decreased with the lower calcium dialysate (P < 0.02) and the set point of calcium was reduced (P < 0.02); in group II, the serum calcium did not change and the set point of calcium was not modified. When both groups were evaluated together, the delta serum calcium correlated directly with the delta set point of calcium (r = 0.87, P < 0.001) and inversely with the delta PTH (r = -0.73, P < 0.005); at the same time, an inverse correlation was observed between the delta PTH and the delta set point of calcium (r = -0.67, P < 0.01). Moreover, the delta serum calcium correlated with both the delta ratio of basal/maximal PTH (r = -0.71, P < 0.005) and the change in predialysis serum calcium necessary to maximally stimulate PTH (r = 0.84, P < 0.001); these latter two are indicators of the position of PTH along the PTH-calcium curve. Finally, in group I the entire PTH-calcium curve shifted to the left on the 1.25 mM calcium dialysate as compared with the 1.75 mM calcium dialysate. CONCLUSION: The findings of the present study indicate that: (1) the set point of calcium followed sustained changes in the serum calcium independently of PTH secretion, and (2) the parathyroid gland was able both to adjust the position of PTH secretion on the PTH-calcium curve and to adapt PTH secretion to the existing serum calcium concentration.

High phosphorus diet increases preproPTH mRNA independent of calcium and calcitriol in normal rats.

Phosphorus retention favors secondary hyperparathyroidism by decreasing calcitriol synthesis and serum calcium levels. However, a direct effect of high extracellular phosphorus on parathyroid (PTH) function, gene expression, and cell proliferation is still controversial. Normal rats were fed standard (St; 0.6% calcium, 0.6% phosphorus) or high phosphate (HP) diet (0.6% calcium, 1.2% phosphorus) for 18 days. To rule out transient decreases in serum calcium or calcitriol levels, sets of animals were sacrificed at different time periods after the last feeding (2, 4, 8, 12 or 24 hr). The HP diet led to hyperphosphatemia and secondary hyperparathyroidism and maximum differences in PTH levels were observed eight hours after feeding (St 29.4 +/- 15 vs. HP 87.9 +/- 56 pg/ml, mean +/- SD; P = 0.01). High levels induced by the HP diet prevented both hypocalcemia and low calcitriol levels at each study point. The HP diet also promoted a significant increase of PTH mRNA levels that peaked about eight hours after feeding (100% increase). This was confirmed at the cellular level by in situ hybridization. Parathyroid glands from animals fed the HP diet showed a 25% increase in volume with respect to the St diet (P = 0.01), and a typical pattern of hyperplasia was found. Parathyroid vitamin D receptor (VDR) mRNA levels were not modified by the HP diet. In conclusion, parathyroid gene expression per cell and parathyroid cell hyperplasia are stimulated by high dietary phosphorus independently of calcium and calcitriol. This effect is not mediated by alterations in the gene expression of the parathyroid calcitriol receptor. Our findings emphasize the importance of the control of hyperphosphatemia in chronic renal failure patients.

Influence of vitamin D receptor genotype on bone mass changes after renal transplantation.

Renal transplant patients immunosuppressed with cyclosporine A (CsA) exhibit both a significant bone loss and an increased rate of bone fractures. An association between common allelic variants of the the vitamin D receptor (VDR) gene and bone mineral density and turnover has been reported in adults. However, the genetic influence on the rate of bone loss after renal transplantation has not been explored. We prospectively determined the changes in spinal mineral density in 34 consecutive nondiabetic adults who received a cadaveric renal allograft. Serum biochemical markers of bone metabolism and the vertebral mineral density (VMD) assessed by quantitative computed tomography were determined at the time of transplantation and three and twelve months later. In fifteen patients the histomorphometric features of iliac bone were analyzed at baseline and twelve months after transplantation. VDR alleles were typed by a PCR assay based on a polymorphic BsmI restriction site. Patients with the so-called "favorable" bb genotype (N = 12) were compared with those with the Bb or BB genotype (N = 22). Baseline VMD was similar in patients with or without the favorable bb genotype. Three months after transplantation the mean (+/- SD) VMD decreased 14 +/- 13.3 percent in all patients (16.5 +/- 13.1% in patients homozygous for the b allele and 13.77 +/- 13.9% in those with Bb or BB genotypes). The rate of VMD loss at this time inversely correlated with pretransplant PTH levels (r = -0.40; P < 0.05). Between 3 and 12 months after transplantation, patients with the favorable bb genotype recovered more VMD than those with Bb or BB types and showed a significantly higher Z score at the end of the follow-up (-0.37 +/- 1.16 vs. -1.10 +/- 1.20, respectively; P < 0.05). The beneficial effect of bb genotype was independent of the prevailing PTH levels and was also observed in those patients with a baseline PTH level < 250 pg/ml (final Z score: bb, -0.42 +/- 1.3, N = 11; Bb/BB, -1.35 +/- 0.8, N = 11, P < 0.05). At the end of follow-up, the histomorphometric studies showed a higher bone formation rate adjusted for PTH levels in patients with the Bb or BB genotype than in those with the favorable bb genotype (0.29 +/- 0.06 vs. 0.21 +/- 0.08 micron3/micron2/day respectively; P < 0.05). In conclusion, high pretransplant PTH levels enhance the early trabecular bone loss after renal transplantation, and functionally different alleles of the vitamin D receptor gene may condition the bone turnover and the degree of recovery of the bone mass.

Abnormal calcaemic response to PTH in the uraemic rat without secondary hyperparathyroidism.

BACKGROUND: Skeletal resistance to the calcaemic action of parathyroid hormone (PTH) is an important pathogenic factor in the development of secondary hyperparathyroidism. Since parathyroidectomy normalizes the calcaemic response to PTH in uraemic animals, the increase in PTH levels has been advanced as a cause of skeletal resistance to the calcaemic action of PTH. This study was designed to evaluate in uraemic rats the effect of normal PTH levels on the calcaemic response to PTH. METHODS: To maintain normal PTH levels, rats were parathyroidectomized (PTX) and rat 1-34 PTH was infused at a rate of 0.022 microg/100 g per hour via a subcutaneously implanted miniosmotic pump; this rate of infusion was considered to be the normal PTH replacement dose since it normalized serum calcium and phosphorus in PTX rats with normal renal function. Two separate studies were performed. In the first study, rats were maintained on a moderate-phosphorus (0.6%) diet and rats were divided into four groups: (I) normal; (II) uraemic; (III) PTX with normal PTH replacement; and (IV) uraemic with PTX and normal PTH replacement. In a second study, the groups were the same except that a high-phosphorus (1.2%) diet was given to increase the magnitude of hyperparathyroidism in rats with intact parathyroid glands; an additional group (V) identical to group IV except that rats received daily calcitriol was included. After 14 days, rats received a 48-h infusion of high-dose rat 1-34 PTH (0.11 microg/100 g per hour) to evaluate the calcaemic response to PTH. Results. The calcaemic response to PTH was similar in normal rats and PTX rats replacement on both a moderate and high-phosphorus diet. In uraemic rats, the calcaemic response to PTH was decreased and the maintenance of normal PTH levels by PTH replacement did not correct the decreased calcaemic response to PTH; moreover, calcitriol supplementation did not improve the calcaemic response to PTH. Finally, hypocalcaemia was observed in uraemic rats with PTH replacement and was more profound than in rats on a high-phosphorus diet. CONCLUSIONS: This study demonstrates that the maintenance of a normal PTH level in uraemic rats did not correct the impaired calcaemic response to PTH, suggesting that factors intrinsic to uraemia, independent of phosphorus, calcitriol, and PTH participate in the decreased calcaemic response to PTH in uraemia.

Relative effects of PTH and dietary phosphorus on calcitriol production in normal and azotemic rats.

In moderate renal failure, the serum calcitriol level is influenced by the stimulatory effect of high PTH and the inhibitory action of phosphorus retention. Our goal was to evaluate the relative effect that high PTH levels and increased dietary phosphorus had on calcitriol production in normal rats (N) and rats with moderate renal failure (Nx). Normal and Nx (3/4 nephrectomy) rats were divided into two groups: (1) rats with intact parathyroid glands (IPTG) and (2) parathyroidectomized rats in which PTH was replaced (PTHR) by the continuous infusion of rat 1-34 PTH, 0.022 microgram/hr/100 g body wt, using a miniosmotic Alzet pump. To test the effect of dietary phosphorus, rats received either a moderate (MPD, 0.6% P) or a high phosphorus (HPD, 1.2%) diet for 14 days. The experimental design included pair-fed N and Nx rats with either IPTG or PTHR. Serum calcitriol and PTH levels in N rats fed a MPD were 69 +/- 3 and 40 +/- 5 pg/ml, respectively. In Nx rats on a MPD, serum calcitriol levels decreased only if hyperparathyroidism was not allowed to occur (76 +/- 4 vs. 62 +/- 4 pg/ml in Nx-IPTG-MPD and Nx-PTHR-MPD groups respectively, P < 0.05). Even in N rats on a HPD, high PTH levels (67 +/- 8 pg/ml in the N-IPTG-HPD group) were required to maintain normal serum calcitriol levels (69 +/- 4 vs. 56 +/- 6 pg/ml in Nx-IPTG-HPD and Nx-PTHR-HPD groups, respectively; P < 0.05). In Nx rats on a HPD, the development of secondary hyperparathyroidism (286 +/- 19 pg/ml in the Nx-IPTG-HPD group) prevented a decrease in serum calcitriol levels (68 +/- 7 pg/ml). In contrast, serum calcitriol levels were low in the Nx-PTHR-HPD group (52 +/- 4 pg/ml, P < 0.05), which were deprived of the adaptative increase in endogenous PTH production. In conclusion, our results in rats indicate that in moderate renal failure, an elevated PTH level maintains calcitriol production and overcomes the inhibitory action of phosphorus retention.

Parathyroid gland calcium receptor gene expression is not regulated by increased dietary phosphorus in normal and renal failure rats.

The extracellular calcium regulation of parathyroid hormone (PTH) secretion is mediated by a cell surface G-protein-coupled calcium receptor (PCaR). The abnormal calcium sensing in renal failure could be the result of abnormalities of the PCaR. However, PCaR gene expression has been shown to be unaffected by 5/6 nephrectomy in the rat. Whether factors that enhance secondary hyperparathyroidism in renal failure affect the PCaR gene expression is not known. We studied normal rats (sham) (n = 40) and renal failure rats (3/4 nephrectomy) (n = 40). Half of the rats in each group received standard (0.6% calcium, 0.6% phosphorus) and half high phosphorus (0.6% calcium, 1.2% phosphorus) diet. Compared to the standard diet, the high phosphorus diet induced secondary hyperparathyroidism both in sham and in renal failure rats (intact PTH: 22.3 +/- 2.03 vs 54.3 +/- 7.6, P < 0.01, and 26.2 +/- 3.9 vs 178.7 +/- 23.2 pg/ml, P < 0.01, respectively). After the cloning of a rat PCaR cDNA fragment corresponding to the extracellular domain which showed an 89% homology with its bovine counterpart, a probe for Northern blot analysis was obtained. No differences in the PCaR mRNA/18s RNA ratio in high phosphorus compared to the standard diet group were observed, both in sham and in renal failure rats. In conclusion, PCaR gene expression is not involved in the genesis of the secondary hyperparathyroidism induced by a high phosphorus diet. An alternative means of increasing PTH secretion by phosphorus loading could be an alteration of the sensitivity of the PCaR to activation by extracellular calcium.

Bone disease in predialysis, hemodialysis, and CAPD patients: evidence of a better bone response to PTH.

The spectrum of bone disease in predialysis and dialysis patients has changed during the last decade. The incidence of aplastic bone disease has increased and this can not be attributed to bone aluminum deposition; moreover, low bone cellular activity is present despite a moderate elevation in PTH levels. This study compares PTH levels and types of bone disease in both predialysis and dialysis patients from the same geographical area. We prospectively studied 119 unselected end-stage renal disease patients: 38 were immediately predialysis (PreD), 49 on hemodialysis (HD), and 32 on CAPD. A bone biopsy was performed in all patients. Aplastic bone disease with < 5% bone surface aluminum was a common finding (48%, 32%, and 48%, in PreD, HD, and CAPD, respectively). In all groups, an intact PTH level below 120 pg/ml was highly predictive of low bone turnover. Conversely, a PTH level above 450 pg/ml was always associated with histologic features of hyperparathyroid bone disease. Among the bone histomorphometric parameters, osteoblast surface showed the best correlation with intact PTH in each group, and the slope of the regression line for this correlation was significantly steeper in HD and CAPD than PreD patients. Thus, the range of PTH (95% confidence limit bands) needed to obtain a normal osteoblast surface of 1.5% was greater in preD than in HD and CAPD patients (300 to 500 vs. 75 to 260 pg/ml, respectively). In all groups some degree of marrow fibrosis was observed when PTH levels were greater than 250 pg/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Adynamic bone disease with negative aluminium staining in predialysis patients: prevalence and evolution after maintenance dialysis.

Aplastic bone disease (ABD) is a common form of renal osteodystrophy and is characterized by a defect in bone matrix formation and mineralization without an increase in osteoid thickness. The prevalence and pathogenesis of ABD in predialysis patients is largely unknown. We prospectively studied 92 unselected predialysis patients with a creatinine clearance < 10 ml/min/1.73 m2 and a mean age of 45 +/- 2 years (61 M, 31 F). None of the study patients had received any form of vitamin D therapy, and CaCO3 was the primary phosphate binder. Aplastic bone disease was observed in 30 (32%) patients. Stainable bone aluminium surface was < 3% in all ABD patients. Patients with ABD were older (52 +/- 3 versus 42 +/- 2 years; P < 0.01) and had reduced serum intact PTH compared to non-ABD patients (199 +/- 25 versus 561 +/- 87 pg/ml; P < 0.001). Patients with diabetes mellitus showed lower PTH values (179 +/- 31 versus 432 +/- 62 pg/ml; P < 0.001) and a lower incidence of advanced hyperparathyroidism bone lesions (16% versus 46%; P < 0.05) than non-diabetic patients. However, diabetes was not clearly associated with low bone turnover disease (56% in diabetics versus 41% in non-diabetics; P = 0.1). A second bone biopsy was obtained in eleven ABD patients after a period of 16.6 +/- 2.2 months on maintenance dialysis with a dialysate calcium of 7 mg/dl. Bone histology was unchanged in 10 patients, and one evolved to mild hyperparathyroidism. Trabecular bone volume did not change (22.7 +/- 1.7 versus 20.7 +/- 1.7%), and the stainable bone aluminium surface remained < 3%.(ABSTRACT TRUNCATED AT 250 WORDS)