De novo germline pathogenic variant in Lynch Syndrome: A rare event or the tip of the iceberg?

Lynch Syndrome is an autosomal dominant cancer predisposition syndrome caused by germline pathogenic variants or epimutation in one of the DNA mismatch repair genes. De novo pathogenic variants in mismatch repair genes have been described as a rare event in Lynch Syndrome (1-5%), although the prevalence of de novo pathogenic variants in Lynch Syndrome is probably underestimated. The de novo pathogenic variant was identified in a 26-year-old woman diagnosed with an adenocarcinoma of the caecum with mismatch repair protein deficiency at immunohistochemistry and a synchronous neuroendocrine tumor of the appendix with normal expression of mismatch repair proteins. DNA testing revealed deletion of exon 6 of the MLH1 gene. It appeared to be a de novo event, as the deletion was not detected in the patient's parents. The presence of a mosaicism in the patient was excluded and haplotype analysis demonstrated the paternal origin of the chromosome harboring the deletion. The de novo deletion probably originated either from a very early postzygotic or a single prezygotic mutational event, or from a gonadal mosaicism. In conclusion, the identification of de novo pathogenic variants is crucial to allow proper genetic counseling and appropriate management of the patient's family.

Whole exome sequencing identifies driver mutations in asymptomatic computed tomography-detected lung cancers with normal karyotype

The efficacy of curative surgery for lung cancer could be largely improved by non-invasive screening programs, which can detect the disease at early stages. We previously showed that 18% of screening-identified lung cancers demonstrate a normal karyotype and, following high-density genome scanning, can be subdivided into samples with 1) numerous; 2) none; and 3) few copy number alterations. Whole exome sequencing was applied to the two normal karyotype, screening-detected lung cancers, constituting group 2, as well as normal controls. We identified mutations in both tumors, including KEAP1 (commonly mutated in lung cancers) in one, and TP53, PMS1, and MSH3 (well-characterized DNA-repair genes) in the other. The two normal karyotype screening-detected lung tumors displayed a typical lung cancer mutational profile that only next generation sequencing could reveal, which offered an additional contribution to the over-diagnosis bias concept hypothesized within lung cancer screening programs.

PALB2 sequencing in Italian familial breast cancer cases reveals a high-risk mutation recurrent in the province of Bergamo

PURPOSE

Monoallelic germ-line deleterious mutations of PALB2 (partner and localizer of BRCA2) are associated with breast cancer risk and have been found in several populations, with carrier frequencies of ~1-2%. Initially, these mutations were considered to have moderate penetrance, but accumulating evidence now indicates that they are associated with much higher risk.

METHODS

In this study, we sequenced the PALB2 coding regions unlinked to BRCA (breast cancer) genes in 575 probands from Italian breast cancer families recruited in Milan.

RESULTS

We found 12 carriers (2.1%) of deleterious mutations, and none of the mutations was found in 784 controls collected in Milan. One of these mutations, the c.1027C>T (p.Gln343X), was found to be recurrent in the province of Bergamo in northern Italy, being detected in 6/113 (5.3%) familial breast cancer cases and 2/477 (0.4%) controls recruited in this area (Fisher's exact test: P < 0.01).

CONCLUSIONS

Our data provide confirmatory findings that, in the Italian population also, deleterious mutations of PALB2 are relatively frequent predisposing factors for breast cancer and may be associated with high risk of the disease.

A non-redundant function of cyclin E1 in hematopoietic stem cells

A precise balance between quiescence and proliferation is crucial for the lifelong function of hematopoietic stem cells (HSCs). Cyclins E1 and E2 regulate exit from quiescence in fibroblasts, but their role in HSCs remains unknown. Here, we report a non-redundant role for cyclin E1 in mouse HSCs. A long-term culture-initiating cell (LTC-IC) assay indicated that the loss of cyclin E1, but not E2, compromised the colony-forming activity of primitive hematopoietic progenitors. Ccne1^−/− mice showed normal hematopoiesis in vivo under homeostatic conditions but a severe impairment following myeloablative stress induced by 5-fluorouracil (5-FU). Under these conditions, Ccne1^−/− HSCs were less efficient in entering the cell cycle, resulting in decreased hematopoiesis and reduced survival of mutant mice upon weekly 5-FU treatment. The role of cyclin E1 in homeostatic conditions became apparent in aged mice, where HSC quiescence was increased in Ccne1^−/− animals. On the other hand, loss of cyclin E1 provided HSCs with a competitive advantage in bone marrow serial transplantation assays, suggesting that a partial impairment of cell cycle entry may exert a protective role by preventing premature depletion of the HSC compartment. Our data support a role for cyclin E1 in controlling the exit from quiescence in HSCs. This activity, depending on the physiological context, can either jeopardize or protect the maintenance of hematopoiesis.

Functional variants at the 11q13 risk locus for breast cancer regulate cyclin D1 expression through long-range enhancers

Analysis of 4,405 variants in 89,050 European subjects from 41 case-control studies identified three independent association signals for estrogen-receptor-positive tumors at 11q13. The strongest signal maps to a transcriptional enhancer element in which the G allele of the best candidate causative variant rs554219 increases risk of breast cancer, reduces both binding of ELK4 transcription factor and luciferase activity in reporter assays, and may be associated with low cyclin D1 protein levels in tumors. Another candidate variant, rs78540526, lies in the same enhancer element. Risk association signal 2, rs75915166, creates a GATA3 binding site within a silencer element. Chromatin conformation studies demonstrate that these enhancer and silencer elements interact with each other and with their likely target gene, CCND1.

Tip60 is a haplo-insufficient tumour suppressor required for an oncogene-induced DNA damage response

The acetyl-transferase Tip60 might influence tumorigenesis in multiple ways. First, Tip60 is a co-regulator of transcription factors that either promote or suppress tumorigenesis, such as Myc and p53. Second, Tip60 modulates DNA-damage response (DDR) signalling, and a DDR triggered by oncogenes can counteract tumour progression. Using E(mu)-myc transgenic mice that are heterozygous for a Tip60 gene (Htatip) knockout allele (hereafter denoted as Tip60+/- mice), we show that Tip60 counteracts Myc-induced lymphomagenesis in a haplo-insufficient manner and in a time window that is restricted to a pre- or early-tumoral stage. Tip60 heterozygosity severely impaired the Myc-induced DDR but caused no general DDR defect in B cells. Myc- and p53-dependent transcription were not affected, and neither were Myc-induced proliferation, activation of the ARF-p53 tumour suppressor pathway or the resulting apoptotic response. We found that the human TIP60 gene (HTATIP) is a frequent target for mono-allelic loss in human lymphomas and head-and-neck and mammary carcinomas, with concomitant reduction in mRNA levels. Immunohistochemical analysis also demonstrated loss of nuclear TIP60 staining in mammary carcinomas. These events correlated with disease grade and frequently concurred with mutation of p53. Thus, in both mouse and human, Tip60 has a haplo-insufficient tumour suppressor activity that is independent from-but not contradictory with-its role within the ARF-p53 pathway. We suggest that this is because critical levels of Tip60 are required for mounting an oncogene-induced DDR in incipient tumour cells, the failure of which might synergize with p53 mutation towards tumour progression.

Atherosclerotic ischemic renal disease

AIM

Atherosclerotic ischemic renal disease is a frequent cause of end-stage renal failure leading to dialysis among the elderly; its prevalence is inferred from autopsy or retrospective arteriographic studies. Screening investigation for ischemic nephropathy on large cohorts, based on non invasive diagnostic techniques, have not so far been published. This study has been conducted on 269 subjects over 50 with hypertension and/or chronic renal failure, unrelated to other known causes of renal disease.

METHODS

All 269 patients were studied either by color-flow duplex sonography (n=238) or by renal scintigraphy (n=224), and 199 of the 269 patients were evaluated using both of these techniques. Forty patients, found to have renal artery stenosis, were subjected to 3D-contrast enhancement magnetic resonance angiography (MRA) and/or digital selective angiography (DSA). An additional 23 cases, negative both to scintigraphy and to ultrasound study, underwent renal angiography (MRA and/or DSA).

RESULTS

Color-duplex sonography, carried out in 238 patients, revealed 49 cases of renal artery stenosis. MR or DSA was carried out in 35 of these 49 patients, and confirmed the diagnosis in 33. Color-duplex sonography was 91.7% sensitive and 90.9% specific, with positive predictive value of 94.2% and negative predictive value of 86.9%. Specificity and sensitivity of renal scintigraphy, carried out in 224 patients, was significantly lower. Patients with renal artery stenosis showed a higher degree of renal insufficiency compared to non stenotic patients while there were no differences in the extent of proteinuria between the two groups. Renal artery stenosis, based on color-duplex sonography studies, was present in 11% of patients in the age group 50-59, 18% in the 60-69 and 23% at age 70 and above.

CONCLUSION

A relatively large percentage of the elderly population with renal insufficiency and/or hypertension is affected by renal artery stenosis and is at risk of developing end-stage renal failure. Color-duplex ultrasonography is a valid routine method of investigation of population at risk for renal artery stenosis.

Urinary composition and lithogenic risk in normal subjects following oligomineral versus bicarbonate-alkaline high calcium mineral water intake

OBJECTIVE

A normal dietary calcium intake to reduce intestinal oxalate absorption is essential to avoid recurrence of calcium oxalate stone formation. It is also important in the prevention of osteopenia in idiopathic hypercalciuria. The calcium content of waters used for hydration may vary from very low to relatively high and is an important factor in prevention or additional risk of stone formation. Therefore, the effect of drinking mineral waters of different calcium concentrations on lithogenic risk factors was studied in normal volunteers.

MATERIALS AND METHODS

Normal subjects were divided into two groups of 11 and 10 individuals each. All followed a prescribed diet with an average calcium content of 800 mg/day. The water intake for hydration consisted of 2 liters of an oligomineral water with a low calcium content, <20 mg/l (group A) or of a bicarbonate alkaline water with a high calcium content, 370 mg/l (group B).

RESULTS

Diuresis increased similarly in both groups; urine calcium increased by about 80 mg/day in group B. A rise in urine oxalate was observed in both groups, along with the increased urine volume. Osmolar excretion increased in group B; urine osmolality decreased significantly only in group A. In spite of the increase in calciuria in group B, Ca/citrate ratio was constant, due to an increase in citrate excretion. Inter-group differences in terms of activity products of calcium phosphate, calculated according with Tiselius's methods, were found. The differences in AP(CaP) index 1 and AP(CaP) index 2 were significant, with higher values in group B, who drank the bicarbonate alkaline mineral water.

CONCLUSIONS

Increased water intake between meals to prevent renal stone recurrence should preferably be achieved with a relatively low calcium water and calcium-rich mineral waters should be avoided.

Parathyroidectomy in chronic renal failure: short- and long-term results on parathyroid function, blood pressure and anemia

To evaluate the long-term results of parathyroidectomy (PTX) on parathyroid function, blood pressure and anemia, data of 45 patients with secondary Hyperparathyroidism in dialysis who had undergone PTX were collected retrospectively from 8 different dialysis units. The patients, 25 M and 20 F, mean age 56 +/- 11 years, who were followed up for an average period of 3.3 +/- 2.3 years, were divided into four groups according to the surgical procedure: 19 patients had had a subtotal PTX; 10 patients had undergone total PTX with autotransplantation (AT); 10 patients had had total PTX without AT, and 6 patients had undergone partial PTX. Taking a reduction in intact PTH > 50% as sign of successful PTX, only 5 patients did not attain this result. Considering values of PTH between 20 and 200 pg/ml at the mid-term observation (1-2 years) as the optimal result, values under 20 pg/ml as an expression of permanent hypoparathyroidism, and those above 200 pg/ml as indicating persistent/recurrent hyperparathyroidism, 65.5% of patients operated with subtotal PTX and total PTX + AT had a therapeutic success, versus 31.2% of patients in the other two groups, due to excess permanent hypoparathyroidism and persistent/recurrent hyperparathyroidism; 20 of 45 patients with preoperative hypertension experienced a statistically and clinically significant decrease in blood pressure levels. An increase in serum hemoglobin was also observed, despite a reduction of administered erythropoietin. In conclusion, the results of PTX obtained from this multicenter study are comparable to those reported by single leading centers. Recommended surgical procedures are subtotal PTX and total PTX with AT. The fall in blood pressure in hypertensive patients is clinically significant, and improvement in anemia is also observed with a reduction in erythropoietin dosage.

Calcitriol per os once, twice or three times a week: effect of different schedules of administration in hemodialysis patients

Administration of a single dose of 1,25-OH(2)D(3) can lower PTH levels for up to 4 days in chronic hemodialysis patients. Our purpose was to verify the effects of the same weekly dose of calcitriol per os given in one, two or three administrations, to patients on dialysis with secondary hyperparathyroidism. Thirty patients were studied, divided in to three groups each of 10 patients. Calcitriol therapy in group A was given as a single weekly dose of 0.08 microg/kg b.w. In group B the same total weekly dose was divided in two equal doses. In group C the same total weekly dose was divided in three times. Treatment lasted 2 months. After 8 weeks of therapy the fall in intact PTH was statistically significant in each group, respectively with one-way ANOVA: p<0.02 (A); p<0.002 (B); p<0.001 (c). Two-way ANOVA for comparison of PTH % variation among the three groups was statistically significant p<0.003. Significance was due to difference between group A and groups B and C. The present study confirms the efficacy of single dose in suppressing significantly intact PTH. However, when the same weekly dose is divided into two or in three time-spaced administrations, the suppressive effects are definitely increased.

Urinary deoxypyridinoline excretion for the evaluation of bone turnover in chronic renal failure

BACKGROUND

The urinary excretion of deoxypyridinoline (DPD) was evaluated in predialysis chronic renal failure (CRF), together with intact PTH and several classic markers of bone turnover in order to assess whether urine free and total DPD excretion are equivalent parameters of bone turnover in CRF, and to evaluate the relationship between urine DPD excretion, PTH and the other bone markers.

METHODS

The study was carried out in 94 patients with different degrees of renal failure due to various kidney diseases. Besides urinary DPD expressed as free DPD, total DPD, free/total DPD, free DPD/Cr and total DPD/Cr, the following determinations were made: intact PTH, bone alkaline phosphatase (BALP), total alkaline phosphatase (AP), osteocalcin (BGP), serum C-terminal telopeptide of collagen type I (ICTP) and hydroxyproline (OHpro). The patients were divided into 3 groups according to the increasing severity of renal failure (Ccr >40, 40-20, <20 ml/min).

RESULTS

The ratio free/total DPD decreased (NS) with advancing renal failure, and was inversely correlated with total DPD excretion. While PTH increased progressively to about four times the values observed in the Ccr >40 group, there was a parallel increase only in BGP and ICTP, parameters retained in the serum with decreasing renal function, while AP, BALP, total DPD and OHpro did not change. However, significant correlations between total DPD/Cr and PTH, BALP, BGP and ICTP were also found.

CONCLUSIONS

In CRF free DPD is an unreliable index of bone turnover due to a probable interference in its production from the peptide-bound DPD. Total DPD or total DPD/Cr are better used. In spite of the significant correlations observed in advanced renal failure between PTH and most of the parameters examined, a resistance of bone tissue to PTH action in CRF must be considered.

Bone markers in the diagnosis of low turnover osteodystrophy in haemodialysis patients

BACKGROUND

Renal osteodystrophy includes a number of low and high turnover bone histologic patterns which require a bone biopsy for their full identification. The role of intact PTH and several classical and more recent bone markers in the non-invasive diagnosis of renal bone disease in patients with CRF in HD requires further definition since available published data are limited.

METHODS

In addition to intact PTH, alkaline phosphatase (AP) and osteocalcin (BGP), bone alkaline phosphatase isoenzyme (BALP), tartrate resistant acid phosphatase (TRAP), C-terminal cross-linked peptide of collagen type 1 (ICTP) and deoxypyridinoline (DPD) were measured in the serum of 41 patients on haemodialysis, subjected at the same time to transiliac bone biopsy for histomorphometric, histodynamic and aluminium histochemical examination. Histodynamic evaluation following double tetracycline label, was carried out in 37 patients. The patients had no evidence of active cytolytic and cholestatic liver disease and a history of very limited aluminium exposure.

RESULTS

The patients had differing degrees of hyper-parathyroidism, with intact PTH ranging from normal to very elevated levels. Serum values of the markers BGP, ICTP and DPD, normally excreted through the kidneys, were on average very high. The correlation coefficients of the humoral parameters vs dynamic variables, such as BFR/BS, were high. The highest values were: intact PTH 0.798, AP 0.900, BALP 0.891, ICTP 0.807. The patients, grouped in low turnover osteodystrophy (LTO; 9), mixed osteodystrophy (MO; 9) and prevalent hyperparathyroidism (HP; 23), showed significant difference in the levels of most humoral and static and dynamic parameters (ANOVA). Bone aluminium histochemistry was negative in all cases. Discrimination of LTO patients from the other groups by humoral parameters, at the highest value of accuracy, showed 100% sensitivity and 93.7% specificity with a cut-off of 12.9 ng/ml for BALP; 88.9% sensitivity and 93.7% specificity with a cut-off of 21.5 ng/ml for DPD, and 88.9% sensitivity and 90.6% specificity with a cut-off of 79.7 pg/ml for intact PTH. The other markers had lower values. A standardized z-score approach for evaluation of all humoral parameters was also carried out. Using all variables, a correct classification of MO/HP and of LTO was possible in 93.8 and 88.9% of the cases, respectively. Predictive power was 96.8 and 80%, respectively for MO/HP and LTO. When the only variables used were intact PTH and BALP, a correct classification of MO/HP and LTO was possible in 90.6% and 88.9%, respectively. Predictive value of MO/HP was 96.7% and for LTO 72.7%. Predictive values using PTH and AP were 96.3% and 57.2%, respectively.

CONCLUSION

Intact PTH and several relatively new bone markers are of certain value in the non-invasive diagnosis of renal osteodystrophy. However some of the humoral markers carry the same quality of information and the use of intact PTH and BALP may be adequate in the discrimination of bone histologic patterns. In cases exempt from liver disease, PTH and AP may be used as a less costly alternative. Bone biopsy could be chiefly limited to cases with borderline humoral values and to all those with a suspected aluminium overload.

Relative roles of intestinal absorption and dialysis-fluid-related exposure in the accumulation of aluminium in haemodialysis patients

BACKGROUND

A recent retrospective study has clearly demonstrated a reduction of cases with positive bone aluminium (Al) staining in the Italian dialysis population, which in general has had a low prevalence of bone Al toxicity. In the present study we tried to better address the relative role played, in our study population, by enteral and parenteral exposure to Al in reducing bone accumulation.

METHODS

We retrospectively examined the data of 105 DFO tests and bone Al determinations performed in dialysis patients from 1984 to 1995. Enternal exposure was analysed by accurate anamnestic records, while parenteral exposure was evaluated by the determination of Al content in dialysis fluids. Bone Al content was assayed chemically and histochemically, while serum Al was assayed spectrophotometrically. Data pertinent to the patients were allotted into three period groups: 1984-1987; 1988-1991; 1992-1995. As for Al concentrations in dialysis fluids, the interval 1980-1983 (immediately before the start of our study), which could clearly have influenced bone Al content, was also considered.

RESULTS

Basal serum Al showed some fluctuations (42.7 +/- 34.1; 24.8 +/- 21.9 and 38.9 +/- 34.9 micrograms/l respectively in the three groups, ANOVA P < 0.01) but only values of the period 1988-1991 were significantly lower than those of the period 1984-1987 (P < 0.05). Increments after DFO did not differ in the three periods (136.5 +/- 105.7; vs 98.7 +/- 91.7 and 106.1 +/- 96.2 micrograms/l respectively, P = n.s.). Enteral exposure to drugs containing Al was comparable (4.1 +/- 2.9 vs 4.0 +/- 4.6 and 5.8 +/- 7.9 total kg ingested respectively; P = n.s.), but bone Al was dramatically reduced (from 60.7 +/- 43.0 to 29.0 +/- 24.4 and 31.9 +/- 29.9 mg/kg/dw respectively; P < 0.0001), along with the definite disappearance of Aluminon-positive cases and Al-related bone disease (ARBD) after 1991. Parenteral exposure through the dialysate dropped from a mean of 26 +/- 14 micrograms/l in the 4-year period prior the start of the study (1980-1983) to 9 +/- 6 micrograms/l in the period 1984-1987 and to 4.9 +/- 2.1 micrograms/l and 5.0 +/- 2.0 micrograms/l respectively thereafter (P < 0.0001).

CONCLUSIONS

Despite the persistence of oral exposure to Al, responsible for the observed stability of serum Al levels, a definite reduction of bone Al content has been recorded in our dialysis population, and ARBD has disappeared. This result has to be referred essentially to the optimal control of Al content in dialysis fluids, which is confirmed as a major factor for Al intoxication.

Renal bone disease in 76 patients with varying degrees of predialysis chronic renal failure: a cross-sectional study

BACKGROUND

Renal osteodystrophy has been studied less extensively in predialysis than in dialysis patients. Different types or histological patterns in their natural evolution from moderate to advanced severity of renal insufficiency are only partially known, with special regard to adynamic bone disease and its relationship with osteomalacia.

METHODS

We conducted a cross-sectional retrospective study on 76 unselected patients with chronic renal failure undergoing conservative treatment, with a wide range of severity of renal insufficiency. All the patients were subjected to bone biopsy for histological and histomorphometric evaluation. The patients, 44 males and 32 females ranging in age from 18 to 72 years and with serum creatinine 1.2-11.4 mg/dl, had not been exposed to aluminium-containing drugs and had never been treated with vitamin D or calcitriol.

RESULTS

Ten patients had normal bone, nine were diagnosed with adynamic bone disease, 26 with mild mixed osteodystrophy, seven with predominant osteomalacia, 22 with advance mixed osteodystrophy, and two with predominant hyperparathyroidism. Patients with adynamic bone disease had less severe chronic renal failure than the other pathological subgroups, intact PTH above the upper limit of normal, normocalcaemia, and reduced serum osteocalcin in line with a significantly lower ObS/BS. Osteomalacia was found in a more advanced stage of chronic renal failure with relative hypocalcaemia and more severe metabolic acidosis. A creatinine clearance of 20 ml/min served as a clear demarcation between this histological group and adynamic bone disease.

CONCLUSIONS

It is postulated that adynamic bone disease is a form of renal osteodystrophy, separate from osteomalacia, appearing when bone resistance to PTH develops, probably a transient stage to more hyperparathyroid histological classes with increasing severity of chronic renal failure.

Intravenous versus oral calcitriol therapy in renal osteodystrophy: results of a prospective, pulsed and dose-comparable study

Intravenous calcitriol is generally considered to be more efficient than oral administration in the treatment of secondary hyperparathyroidism of chronic renal failure, although a comparative and prospective study employing the same doses and modality of drug administration is lacking. We therefore evaluated 12 hemodialysis (HD) patients (51.7 +/- 9.4 years, mean +/- SD, HD for 8.7 +/- 4.7 years) with marked secondary hyperparathyroidism. Based on basal humoral and bone histologic parameters, we divided these patients into 2 comparable groups. Calcitriol (0.015 micrograms/kg) was given at the end of each dialysis intravenously in group A and orally in group B. Humoral parameters were evaluated basally and after 1, 2, 4 and 8 months. Ax bone biopsy was taken at the start and at the end of the study. From the first month of treatment, group A showed an increment in ionized calcium (from 1.28 +/- 0.08 to 1.37 +/- 0.12 mmol/l, p < 0.01), with a reduction in intact parathyroid hormone (from 470.1 +/- 349.5 to 255.5 +/- 256.5 pg/ml; p < 0.0003) and alkaline phosphatase (from 615.1 +/- 696.3 to 445.3 +/- 577.7 mU/ml, p < 0.001). The occurrence of hypercalcemia prompted a reduction in dialysate calcium content in 4 of 6 patients after 4 months, and of the calcitriol dose in 2 of 4 patients after 6 months. Ionized calcium then turned to 1.32 +/- 0.11 (p = n.s. compared to basal) while the intact parathyroid hormone concentration tended to revert (363.3 +/- 360 pg/ml, p = n.s. compared to basal) and alkaline phosphatase remained low (420 +/- 638 mU/ml, p < 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)

Procollagen type 1 C-terminal extension peptide serum levels following parathyroidectomy in hyperparathyroid patients

Procollagen type 1 is mainly synthesized by osteoblasts and, after cleavage of the N- and C-terminal extension peptides, is utilized for collagen fibril deposition in the osteoid tissue. Serum levels of C-terminal extension peptide (Pcoll-1-C) of the procollagen molecule has been considered a useful marker for the evaluation of the rate of osteoblastic procollagen synthesis. To appraise whether in vivo parathyroid hormone (PTH) plays a suppressive role in the synthesis of procollagen type 1, a study has been carried out in 16 patients, 10 with severe secondary hyperparathyroidism of chronic renal failure and 6 with primary hyperparathyroidism. Following parathyroidectomy (PTX), in chronic renal failure patients a 94% fall in serum intact iPTH and a decline of serum calcium to hypocalcemic levels requiring calcitriol administration were observed. Serum Pcoll-1-C increased markedly with a peak after 7 days and a subsequent decline. Similar changes were observed for alkaline phosphatase and osteocalcin. In primary hyperparathyroidism, PTX was followed by an 88% drop in iPTH and mild hypocalcemia not requiring calcitriol administration. Also in this group serum Pcoll-1-C increased significantly with the same time course, unaccompanied by changes in alkaline phosphatase and osteocalcin. In 4 unsuccessfully neck-operated control patients no change in serum Pcoll-1-C levels was recorded during a period of 2 weeks postoperatively. In conclusion, acute withholding of parathyroid hypersecretion is accompanied by an abrupt and transitory increase of serum Pcoll-1-C, not dependent on calcitriol administration. Hypocalcemia following PTX may in part be due to uncoupling of bone formation and resorption.

Two-site immunoradiometric intact parathyroid hormone assay versus C-terminal parathyroid hormone in predicting osteodystrophic bone lesions in predialysis chronic renal failure

Intact parathyroid hormone (iPTH) radioimmunoassay represents an important advancement in the measurement of serum PTH levels, permitting the evaluation of the actual rate of secretion of the parathyroid glands. The aim of the study was to compare the value of intact and C-terminal PTH measurements in predicting the osteodystrophic bone lesion in predialysis patients with chronic renal failure (CRF). We have studied 37 subjects with CRF who were receiving conservative treatment. In each subject a transiliac bone biopsy for histomorphometric examination was performed in addition to the assay of serum intact and C-terminal PTH, osteocalcin, and alkaline phosphatase. Serum C-terminal and intact PTH levels were closely correlated, both showing a high degree of correlation with serum osteocalcin. Similar degrees of correlation were observed between the two PTH assays and the histologic parameters osteoblastic surface (ObS/BS) and osteoclastic surface (OcS/BS). The evaluation of specificity and sensitivity of the two PTH assays in selecting patients with normal or pathologic histomorphometric parameters gave an equivalent number of false positive and negative cases. Based on discriminant analysis of histomorphometric parameters, intact PTH shows a higher discriminant power when compared with C-terminal PTH assay for the parameters OcS/BS and eroded surface (ES/BS), but without practical clinical value. In conclusion, in analogy to the short lived N-terminal PTH fragment assay, prediction of elementary hyperparathyroid bone lesions in predialysis CRF is not improved by the use of intact PTH as compared to the more traditional C-terminal assay.

Biologic effect of 1,24(R)(OH)2D3 versus 1,25(OH)2D3 administration in chronic renal failure

1,24(R)(OH)2D3 is a synthetic analogue of 1,25(OH)2D3 which binds to the same receptors as the physiologic metabolite with a lower affinity. The aim of the present study was to compare the activity of 1,24(R)(OH)2D3 and 1,25(OH)2D3 on several target organs in patients with chronic renal failure. Treatment with 1,24(R)(OH)2D3 at doses of either 1 or 2 micrograms daily was carried out in two groups of 9 patients, with serum creatinine of 4.61 +/- 1.59 and 4.66 +/- 1.46 mg/dl, respectively. Doses of 1,25(OH)2D3 were 0.5 and 1 microgram daily and were administered to 9 and 13 patients, serum creatinine of 4.52 +/- 1.67 and 4.3 +/- 1.16 mg/dl, respectively. Treatment periods were of 2 weeks. Administration of 1,25(OH)2D3, 1 microgram, induced significant increments of intestinal calcium absorption (ICA), ionized calcium, osteocalcin, serum creatinine, urine Ca/GFR, and a decrease in iPTH. 1,25(OH)2D3, 0.5 microgram, induced a significant increase in ICA and osteocalcin and a decrease in iPTH. Similarly 1,24(OH)2D3, 2 micrograms daily, significantly stimulated ICA and raised serum levels of osteocalcin and creatinine while lowering serum iPTH. In addition, 1,24(R)(OH)2D3 administration induced a significant fall of serum 1,25(OH)2D3. Following 1 microgram, only osteocalcin increased. Therefore, the dose of 2 micrograms of 1,24(R)(OH)2D3 has biologic activity similar to 0.5 microgram 1,25(OH)2D3 (4:1). However the activity ratio on osteocalcin production appears to be 2:1. In addition, 1,24(R)(OH)2D3 is able to inhibit renal tubular 1 alpha-hydroxylase. In conclusion 1,24(R)(OH)2D3 may prove to be useful in the treatment of metabolic bone disease.

Procollagen type I C-terminal extension peptide in predialysis chronic renal failure

Collagen type 1 is the most abundant protein of bone. Serum levels of type 1 procollagen carboxy-terminal extension peptide (Procoll-1-C) may give a measure of the rate of synthesis of the collagen of bone and be therefore a marker of bone turnover. We have studied 38 patients with predialysis chronic renal failure; 14 of them were under long-term treatment with 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] for prevention of secondary hyperparathyroidism. In all patients a transiliac bone biopsy for histomorphometry and determination of dynamic parameters was performed following double tetracycline labeling. In addition serum Procoll-1-C, intact and C-terminal parathyroid hormone (PTH), osteocalcin and alkaline phosphatase were determined. In the patients not receiving 1,25(OH)2D3, serum levels of Procoll-1-C were higher than normal. Procoll-1-C did not correlate with any of the humoral parameters, including serum creatinine, nor with static histomorphometric parameters. Contrarily to osteocalcin, the collagen type 1 marker correlated significantly with all dynamic parameters. Treatment with 1,25(OH)2D3 was accompanied by lower levels of osteocalcin, iPTH (n.s.), osteoblastic surface and by normal levels of Procoll-1-C (p < 0.001, compared to untreated patients), without substantial change in bone formation parameters (bone formation rate). In conclusion Procoll-1-C in predialysis chronic renal failure is a marker of bone turnover unparalleled by other markers. 1,25(OH)2D3 administration is associated with lower serum levels of the peptide unaccompanied by a decrement of bone formation parameters, therefore with an apparently better utilization of collagen type 1 in the mineralization process.(ABSTRACT TRUNCATED AT 250 WORDS)

Deferoxamine test and PTH serum levels are useful not to recognize but to exclude aluminum-related bone disease

The use of noninvasive diagnostic tools, like the deferoxamine (DFO) test and serum iPTH, to identify aluminum-related bone disease has proved to be inadequate due to false-negative cases; therefore, bone biopsy becomes a necessary diagnostic procedure. Our purpose was to verify whether these non-invasive parameters, appropriately used, may result valid in the identification of patients not at risk of Al toxicity, therefore restricting the need for histologic evaluation. We studied 68 hemodialyzed patients, aged 49.0 +/- 11.6 years, with a M/F ratio of 37/31 and a dialytic age of 85.0 +/- 47.0 months, by means of bone biopsy, DFO test and serum C-PTH. 19.1% of the cases had positive stainable Al and/or high bone Al content (greater than 60 mg/kg/dw) and could be intoxicated. To obtain the highest sensitivity, we selected the following limit values: the lower limit of increment so far proposed for DFO test positivity (greater than 150 micrograms/l) and a value capable of selecting patients with pathologic osteoclasia for C-PTH (greater than 15 ng/ml). With these limits, four different groups of patients were recognized: group A, DFO test positive and PTH high, n = 12; group B, DFO test positive and PTH low, n = 6; group C, DFO test negative and PTH high, n = 30; group D, DFO test negative and PTH low, n = 20. In group B, which could be anticipated as being at higher risk, we actually found the highest (p less than 0.05) bone Al content as compared to other groups, associated with a reduced bone formation rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic neuropathy and secondary hyperparathyroidism in uraemia

To evaluate the relationship between autonomic neuropathy, and biochemical and X-ray parameters of secondary hyperparathyroidism, we examined 19 predialysis and 24 haemodialysis non-diabetic uraemic patients. Autonomic neuropathy was assessed using four tests: deep breathing, Valsalva manoeuvre, lying to standing, and postural hypotension. Serum Ca, Ca2+, P, Mg, alkaline phosphatase, iPTH, and osteocalcin were assayed. Hand X-ray was obtained to evaluate acro-osteolysis (score A) and subperiosteal resorption (score B). Ten predialysis patients (52%) and 15 haemodialysis patients (62%) showed one or more abnormal autonomic tests. Age, dialysis duration, and biochemical parameters of secondary hyperparathyroidism did not differ significantly in uraemic patients with and without abnormal autonomic tests. Furthermore, there was no significant relation between autonomic tests and iPTH or osteocalcin. Score A and score B was significantly greater in patients with abnormal tests than in patients without (P less than 0.009 and P less than 0.025). When predialysis and haemodialysis patients were considered separately the correlation between score A, score B, and autonomic neuropathy was confirmed only in haemodialysis patients. In conclusion, autonomic neuropathy does not seem to be related to the biochemical parameters of secondary hyperparathyroidism, while it appears significantly associated with the radiological signs of osteodystrophy, suggesting a possible pathogenetic linkage between autonomic neuropathy and secondary hyperparathyroidism.

Osteocalcin, iPTH, alkaline phosphatase and hand X-ray scores as predictive indices of histomorphometric parameters in renal osteodystrophy

To evaluate the relationship between hyperparathyroid bone X-ray lesion, biochemical parameters and bone histology in chronic renal failure, 59 patients (52 +/- 14.9 years; Crs 4.7 +/- 2.2 mg/dl, mean +/- SD) on conservative treatment and 103 (48 +/- 14 years) on hemodialysis (from 48.4 +/- 36.7 months) were studied. Right-hand X-ray was carried out for evaluation of the scores (0-3) of acroosteolysis (score A) and subperiosteal resorption (score B). Serum iPTH, osteocalcin and alkaline phosphatase (AP) were measured. In addition in a subset of 53 patients, 30 in predialysis and 23 in dialysis, a bone biopsy was performed for histomorphometry. In predialysis the scores A and B correlated with bone GLA protein (BGP) (p less than 0.01), AP (p less than 0.05) and osteoid surface (p less than 0.05) and 0.01 respectively). In hemodialysis the same level of significant correlation (p less than 0.001) was found between the scores and the three humoral parameters. Score A correlated with active osteoblastic surface and active resorption surface while score B correlated with active osteoblastic surface (p less than 0.01), osteoid surface and active resorption surface (p less than 0.05). Multiple regression analysis carried out to establish the predictive variables of bone histologic lesions (active resorption surface and active osteoblastic surface) singled out BGP in predialysis and AP and the two scores in dialysis. We conclude that serum BGP, as compared to PTH and AP, prevails as a valid marker of hyperparathyroid bone lesion in predialysis, while in dialysis it does not seem to add further information to that carried by other variables.(ABSTRACT TRUNCATED AT 250 WORDS)