Molecular analysis and genotype-phenotype correlation of Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) features hypoplastic anemia and congenital malformations, largely caused by mutations in various ribosomal proteins. The aim of this study was to characterize the spectrum of genetic lesions causing DBA and identify genotypes that correlate with phenotypes of clinical significance. Seventy-four patients with DBA from across Canada were included. Nucleotide-level mutations or large deletions were identified in 10 ribosomal genes in 45 cases. The RPS19 mutation group was associated with higher requirement for chronic treatment for anemia than other DBA groups. Patients with RPS19 mutations, however, were more likely to maintain long-term corticosteroid response without requirement for further chronic transfusions. Conversely, patients with RPL11 mutations were less likely to need chronic treatment. Birth defects, including cardiac, skeletal, hand, cleft lip or palate and genitourinary malformations, also varied among the various genetic groups. Patients with RPS19 mutations had the fewest number of defects, while patients with RPL5 had the greatest number of birth defects. This is the first study to show differences between DBA genetic groups with regards to treatment. Previously unreported differences in the rate and types of birth defects were also identified. These data allow better patient counseling, a more personalized monitoring plan, and may also suggest differential functions of DBA genes on ribosome and extra-ribosomal functions.

Embryonal tumors in Canadian children less than 36 months of age: results from the Canadian Pediatric Brain Tumor Consortium (CPBTC).

Embryonal tumors are a heterogeneous group of central nervous system (CNS) tumors whose subgroups have varying incidence and outcome. Despite these differences, they are often grouped as a single entity for study purposes. To date, there are no Canadian multi-institutional studies examining the incidence and outcome of all embryonal subtypes. The current study is an observational study reviewing embryonal tumors in all patients less than 36 months of age diagnosed with a CNS tumor in Canada from 1990 to 2005. Embryonal tumors accounted for 26.9% of all CNS tumors. Medulloblastomas were the highest proportion of the embryonal tumors at 61.5%. Atypical teratoid/rhabdoid tumors (AT/RT) had the second highest proportion of embryonal tumors at 18%. The proportion of primitive neuroectodermal tumors (PNET) was 16%, with 2.6 and 1.9% for congenital medulloepithelioma and ependymoblastoma tumors, respectively. AT/RT and PNET were more common in younger age groups. Medulloblastoma became more prevalent with increasing age, with its highest prevalence in the 25 to 36 month age group. Survival rates for our Canadian population at 18 and 24 months were 0.74 and 0.68 for medulloblastoma, 0.64 and 0.60 for PNET, and 0.36 and 0.29 for AT/RT, respectively. Overall, our data are comparable with published international rates for embryonal tumors. These incidence and outcome figures can guide future research into these rare tumors.

Silicon micromachined ultrasonic scalpel for the dissection and coagulation of tissue.

This work presents a planar, longitudinal mode ultrasonic scalpel microfabricated from monocrystalline silicon wafers. Silicon was selected as the material for the ultrasonic horn due to its high speed of sound and thermal conductivity as well as its low density compared to commonly used titanium based alloys. Combined with a relatively high Young's modulus, a lighter, more efficient design for the ultrasonic scalpel can be implemented which, due to silicon batch manufacturing, can be fabricated at a lower cost. Transverse displacement of the piezoelectric actuators is coupled into the planar silicon structure and amplified by its horn-like geometry. Using finite element modeling and experimental displacement and velocity data as well as cutting tests, key design parameters have been identified that directly influence the power efficiency and robustness of the device as well as its ease of controllability when driven in resonance. Designs in which the full- and half-wave transverse modes of the transducer are matched or not matched to the natural frequencies of the piezoelectric actuators have been evaluated. The performance of the Si micromachined scalpels has been found to be comparable to existing commercial titanium based ultrasonic scalpels used in surgical operations for efficient dissection of tissue as well as coaptation and coagulation of tissue for hemostasis. Tip displacements (peak-to-peak) of the scalpels in the range of 10-50 µm with velocities ranging from 4 to 11 m/s have been achieved. The frequency of operation is in the range of 50-100 kHz depending on the transverse operating mode and the length of the scalpel. The cutting ability of the micromachined scalpels has been successfully demonstrated on chicken tissue.

A sustainable approach toward mechanical recycling unsortable post-consumer WEEE: Reactive and non-reactive compatibilization.

While near-infrared (NIR) spectroscopy in post-consumer waste electrical and electronic equipment (WEEE) recycling accurately separates white or clear polymers, 40% containing dark plastics, termed 'unsortable WEEE,' are excluded from sorting lines and therefore incinerated or landfilled, causing environmental concerns. This study investigates the potential of using non-reactive and reactive copolymers as compatibilizers to enhance the performance of unsortable WEEE plastics free of brominated flame retardants. To the best of our knowledge, this is the first time that such copolymers have been explored as a solution for improving the compatibility of unsortable WEEE polymer blends. Initial trials with 4% of styrene-ethylene-butylene-styrene copolymer (SEBS-13) and SEBS-30-g-(maleic anhydride) copolymer (SEBS-30-g-MA MA) as compatibilizers showed insufficient results compared to virgin commercial polymers. However, the addition of higher concentrations of compatibilizers (i.e. up to 20 wt%) and the use of a SEBS having a higher styrene content (i.e. SEBS-30) improved the mechanical properties of the material, causing it to transition from brittle to ductile. This behavior was found more pronounced for the 20% non-reactive SEBS-30, for which the SEM analysis showed reduced phase segregation and revealed a more homogeneous fracture surface. This was further supported by Differential Scanning Calorimetry (DSC) analysis, which showed evidence of an interaction between one or more polymer phases. With a room temperature performance equivalent to that of virgin conventional polymers, the SEBS-30 compatibilization approach has made it possible to consider using unsortable WEEE streams as recycled materials in commercial applications.

Invasive fungal infections in paediatric acute myeloid leukaemia.

Invasive fungal infections (IFIs) are a major cause of morbidity and mortality in paediatric acute myeloid leukaemia (AML). This study describes risk factors for IFI and IFI-related sepsis in this population. We conducted a population-based, retrospective cohort study of children with AML in Canada. IFIs during chemotherapy and prior to haematopoietic stem cell transplantation, relapse, persistent disease or death were identified. Risk factors for proven or probable IFI were examined. Among courses complicated by IFI, risk factors for sepsis were also evaluated. There were 341 children with AML included of which 41 (12.0%) experienced 46 different episodes of IFI. Candida species accounted for 23 (50.0%) of IFIs and Aspergillus spp. accounted for 14 (30.4%). Days of broad-spectrum antibiotics, days of corticosteroids and neutropenia at start of the course were independently associated with IFI. Only days of fever were independently associated with IFI-related sepsis. Invasive fungal infections occurred in 12.0% of paediatric AML patients. Risk factors for IFI and IFI-related sepsis were identified. This knowledge may help to consider targeted strategies.

Genetic analysis of inherited bone marrow failure syndromes from one prospective, comprehensive and population-based cohort and identification of novel mutations.

INTRODUCTION: Inherited bone marrow failure syndromes (IBMFSs) often have substantial phenotypic overlap, thus genotyping is often critical for establishing a diagnosis. OBJECTIVES AND METHODS: To determine the genetic characteristics and mutation profiles of IBMFSs, a comprehensive population-based study that prospectively enrols all typical and atypical cases without bias is required. The Canadian Inherited Marrow Failure Study is such a study, and was used to extract clinical and genetic information for patients enrolled up to May 2010. RESULTS: Among the 259 primary patients with IBMFS enrolled in the study, the most prevalent categories were Diamond-Blackfan anaemia (44 patients), Fanconi anaemia (39) and Shwachman-Diamond syndrome (35). The estimated incidence of the primary IBMFSs was 64.5 per 10(6) births, with Fanconi anaemia having the highest incidence (11.4 cases per 10(6) births). A large number of patients (70) had haematological and non-haematological features that did not fulfil the diagnostic criteria of any specific IBMFS category. Disease-causing mutations were identified in 53.5% of the 142 patients tested, and in 16 different genes. Ten novel mutations in SBDS, RPL5, FANCA, FANCG, MPL and G6PT were identified. The most common mutations were nonsense (31 alleles) and splice site (28). Genetic heterogeneity of most IBMFSs was evident; however, the most commonly mutated gene was SBDS, followed by FANCA and RPS19. CONCLUSION: From this the largest published comprehensive cohort of IBMFSs, it can be concluded that recent advances have led to successful genotyping of about half of the patients. Establishing a genetic diagnosis is still challenging and there is a critical need to develop novel diagnostic tools.

Comparative analysis of Shwachman-Diamond syndrome to other inherited bone marrow failure syndromes and genotype-phenotype correlation.

Our knowledge of the phenotypes of inherited bone marrow failure syndromes (IBMFSs) derives from case reports or case series in which only one IBMFS was studied. However, the substantial phenotypic overlap necessitates comparative analysis between the IBMFSs. Shwachman-Diamond syndrome (SDS) is an IBMFS that the appreciation of what comprises its clinical phenotype is still evolving. In this analysis we used data on 125 patients from the Canadian Inherited Marrow Failure Study (CIMFS), which is a prospective multicenter population-based study. Thirty-four cases of SDS patients were analyzed and compared to other patients with the four most common IBMFSs on the CIMFS: Diamond Blackfan anemia, Fanconi anemia (FA), Kostmann/severe congenital neutropenia and dyskeratosis congenita (DC). The diagnosis of SDS, FA and DC was often delayed relative to symptoms onset; indicating a major need for improving tools to establish a rapid diagnosis. We identified multiple phenotypic differences between SDS and other IBMFSs, including several novel differences. SBDS biallelic mutations were less frequent than in previous reports (81%). Importantly, compared to patients with biallelic mutations, patients with wild type SBDS had more severe hematological disease but milder pancreatic disease. In conclusion, comprehensive study of the IBMFSs can provide useful comparative data between the disorders. SBDS-negative SDS patients may have more severe hematological failure and milder pancreatic disease.

Absence of p53 gene mutations in primary neuroblastomas.

Neuroblastoma is a common childhood malignancy of the sympathetic nervous system. Mutations in p53, a tumor suppressor gene located on the short arm of chromosome 17, are one of the most common genetic lesions in human cancers. The evidence for trisomies of 17q with loss of 17p in some cases of neuroblastoma led us to consider whether p53 mutations might contribute to the onset and progression of this malignancy. In this study, primary tumors from 38 neuroblastoma patients were screened for mutations within the coding exons of the p53 gene by single-strand conformation polymorphism analysis, and potential mutations were further analyzed by nucleotide sequence analysis. Previously described sequence variations were detected in many of the tumors, including a silent polymorphism at codon 213 (CGA to CGG) and the nontransforming Pro to Arg substitution at codon 72 (CCC to CGC). However, no other sequence variations were detected within the coding portions of the p53 gene. This finding suggests that p53 mutations do not contribute to the etiology of neuroblastoma and that the chromosome 17 alterations observed in neuroblastoma involve genes which are distinct from the p53 locus.

Lack of involution of hyperplastic parathyroid glands in dogs: adaptation via a decrease in the calcium stimulation set point and a change in secretion profile.

This study analyzes the parathyroid function in four dogs before and after 2 years of a low-calcium, high-sodium, vitamin D-deficient diet and the involution of the same function following (1) correction of dietary calcium deficiency and administration of i.v. 1,25-(OH)2D (0.25 micrograms twice per day) during 1 month, (2) after an additional month of normal dog chow supplemented with oral vitamin D (25 micrograms per day), and, finally, (3) after 5 and 17 months of a diet with normal levels of calcium and vitamin D. The parathyroid function was evaluated through i.v. infusion of CaCl2 and Na2 EDTA with measurement of intact (I) and carboxyl-terminal (C) immunoreactive parathyroid hormone (iPTH). The C-iPTH/I-iPTH ratio was calculated to assess the modulation of molecular forms of iPTH induced by the various treatments. The 2 years of calcium and vitamin D deprivation lowered ionized calcium (1.23 +/- 0.04, p < 0.05) and 25-OHD (4.02 +/- 2.06 nM, p < 0.005) and tended to decrease 1,25-(OH)2D (80.8 +/- 8.6 pM); it increased basal I- and C-iPTH levels approximately eightfold (I-iPTH, 40.2 +/- 20.7, p < 0.05; C-iPTH, 185.4 +/- 94.9, p < 0.05) and stimulated I-iPTH (60.2 +/- 23.0 pM, p < 0.05) and C-iPTH (239.6 +/- 80.7 pM, p < 0.05) fivefold. A greater rise in nonsuppressible I-iPTH levels than in C-iPTH levels led to a decreased C-iPTH/I-iPTH ratio in hypercalcemia (12.5 +/- 2.8 versus 27.8 +/- 6.05 pM, p < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Synthetic carboxyl-terminal fragments of parathyroid hormone (PTH) decrease ionized calcium concentration in rats by acting on a receptor different from the PTH/PTH-related peptide receptor.

Even if the carboxyl-terminal (C-) fragments/intact (I-) PTH ratio is tightly regulated by the ionized calcium (Ca(2+)) concentration in humans and animals, in health and in disease, the physiological roles of C-PTH fragments and of the C-PTH receptor remain elusive. To explore these issues, we studied the influence of synthetic C-PTH peptides of various lengths on Ca(2+) concentration and on the calcemic response to human (h) PTH-(1-34) and hPTH-(1-84) in anesthetized thyroparathyroidectomized (TPTX) rats. We also looked at the capacity of these PTH preparations to react with the PTH/PTHrP receptor and with a receptor for the carboxyl (C)-terminal portion of PTH (C-PTH receptor) in rat osteosarcoma cells, ROS 17/2.8. The Ca(2+) concentration was reduced by 0.19 +/- 0.03 mmol/liter over 2 h in all TPTX groups. Infusion of solvent over 2 more h had no further effect on the Ca(2+) concentration (-0.01 +/- 0.01 mmol/liter), whereas infusion of hPTH-(7-84) or a fragment mixture [10% hPTH-(7-84) and 45% each of hPTH-(39-84) and hPTH-(53-84)] 10 nmol/h further decreased the Ca(2+) concentration by 0.18 +/- 0.02 (P<0.001) and 0.07+/-0.04 mmol/liter (P< 0.001), respectively. Infusion of hPTH-(1-84) or hPTH-(1-34) (1 nmol/h) increased the Ca(2+) concentration by 0.16 +/- 0.03 (P < 0.001) and 0.19 +/- 0.03 mmol/liter (P < 0.001), respectively. Adding hPTH-(7-84) (10 nmol/h) to these preparations prevented the calcemic response and maintained Ca(2+) concentrations equal to or below levels observed in TPTX animals infused with solvent alone. Adding the fragment mixture (10 nmol/h) to hPTH-(1-84) did not prevent a normal calcemic response, but partially blocked the response to hPTH-(1-34), and more than 3 nmol/h hPTH-(7-84) prevented it. Both hPTH-(1-84) and hPTH-(1-34) stimulated cAMP production in ROS 17/2.8 clonal cells, whereas hPTH-(7-84) was ineffective in this respect. Both hPTH-(1-84) and hPTH-(1-34) displaced (125)I-[Nle(8,18),Tyr(34)]hPTH-(1-34) amide from the PTH/PTHrP receptor, whereas hPTH-(7-84) had no such influence. Both hPTH-(1-84) and hPTH-(7-84) displaced (125)I-[Tyr(34)]hPTH-(19-84) from the C-PTH receptor, the former preparation being more potent on a molar basis, whereas hPTH-(1-34) had no effect. These results suggest that C-PTH fragments, particularly hPTH-(7-84), can influence the Ca(2+) concentration negatively in vivo and limit in such a way the calcemic responses to hPTH-(1-84) and hPTH-(1-34) by interacting with a receptor different from the PTH/PTHrP receptor, possibly a C-PTH receptor.

Carboxyl-terminal fragments of parathyroid hormone are not secreted preferentially in primary hyperparathyroidism as they are in other hypercalcemic conditions.

Calcium infusion in normal men decreases immunoreactive PTH (iPTH). Intact iPTH (I) shows the greatest decline, and there is a greater decrease in carboxyl-terminal iPTH (C) than in midcarboxyl-terminal iPTH (M); thus, C/I, M/I, and M/C ratios are increased. To verify whether this adaptive mechanism to hypercalcemia was present in patients with primary hyperparathyroidism (PHP), we measured total serum calcium (Ca), I, C, and M as well as C/I, M/I, and M/C ratios in 32 normocalcemic normal subjects (NN), in the same normal subjects made hypercalcemic (HN), in 31 patients with PHP, and in 12 patients with nonparathyroid hypercalcemia (NPHN). Eight patients with PHP and the 32 NN were submitted to CaCl2 and Na2 EDTA infusions to evaluate their parathyroid function. Ca was lower (P < 0.005) in NN (2.21 +/- 0.06 mmol/L) than in PHP (2.80 +/- 0.25 mmol/L) or NPHN (2.83 +/- 0.20 mmol/L). The HN Ca value (2.80 +/- 0.18 mmol/L) was similar to those in PHP and NPHN subjects. C, M, and I were increased in PHP compared to the other groups (P < 0.005). PHP had C/I and M/I ratios of 2.03 +/- 0.72 and 9.04 +/- 7.69, values similar to NN (2.29 +/- 0.55 and 8.70 +/- 3.0), but lower than HN (5.36 +/- 2.48 and 25.93 +/- 13.86; P < 0.005) and NPHN (11.91 +/- 13.06 and 18.69 +/- 10.81; P < 0.005). NPHN also had a lower M/C ratio than HN (2.76 +/- 2.02 vs. 4.99 +/- 1.81; P < 0.05). PHP and NN could increase their C/I ratio to the same maximum (4.71 +/- 1.26 vs. 5.70 +/- 2.94), but PHP did so at a much higher set-point (2.67 +/- 0.19 vs. 2.24 +/- 0.10 mmol/L; P < 0.005). PHP also had higher set-points for M/I, and M/C ratios even if they failed to increase the ratios to the high values in NN [M/I 11.6 +/- 6.4 vs. 29.3 +/- 18.3 (P < 0.005); M/C, 2.16 +/- 1.20 vs. 5.0 +/- 1.93 (P < 0.005)]. Thus, carboxyl-terminal fragments are not secreted preferentially in PHP as they are in other hypercalcemic conditions. This relates to a higher set-point for the regulation of C/I and M/I ratios, permitting the secretion of more intact hormone relative to C or M fragments. The lower M/C ratio in NPHN and in PHP made more hypercalcemic compared to HN suggests a lower production or a higher clearance of midcarboxyl-terminal fragments in chronic hypercalcemia.

Accumulation of a non-(1-84) molecular form of parathyroid hormone (PTH) detected by intact PTH assay in renal failure: importance in the interpretation of PTH values.

A molecular form of PTH different from PTH-(1-84) and present in normal serum is recognized by two-site intact (I-) PTH assays; it responds to Ca2+ changes in the same way that PTH carboxyl-terminal fragments do. To evaluate the impact of this finding, we have compared basal, stimulated, and nonsuppressible I-PTH values in 14 normal subjects and 15 renal failure patients, subdivided into 8 patients with low (< 12 pmol/L; LBI) and 7 with high (> 12 pmol/L; HBI) basal I-PTH. Samples obtained under various calcemic conditions in these 3 groups were further fractionated by high performance liquid chromatography (HPLC) and assayed for I-PTH, and the various peaks observed were quantitated by planimetry. Differences among the 3 groups were reinterpreted knowing the exact composition of I-PTH. Basal I-PTH was greatly increased in HBI (mean +/- SD, 44.1 +/- 38.6 pmol/L) compared to that in normal subjects (2.5 +/- 0.8 pmol/L; P < 0.001) or LBI (6.1 +/- 2.4 pmol/L; P < 0.001); the difference was less in these last 2 groups (P < 0.01). Similar differences were observed for stimulated and nonsuppressible I-PTH, except for stimulated I-PTH, which was similar in normal and LBI subjects. Two I-PTH HPLC molecular forms accounted for I-PTH immunoreactivity in the 3 groups. In normal subjects, PTH-(1-84) accounted for 74.9 +/- 4.3%, 79.0 +/- 3.0%, and 87.2 +/- 1.0% of I-PTH in hyper-, normo-, and hypocalcemia, respectively, but only for 44.6 +/- 2.5%, 50.5 +/- 0.7%, and 63.6 +/- 0.1% in renal failure patients, with similar results in HBI and LBI. The accumulation of a non-(1-84) PTH peak accounted for the difference between normal subjects and renal failure patients. When basal, stimulated, and nonsuppressible I-PTH values were separated into their 2 components, prior differences between HBI and LBI or normal subjects remained unchanged because of very high I-PTH values in HBI, but differences between normal and LBI subjects were entirely explained by the accumulation of the non-(1-84) PTH peak [basal, 3.0 +/- 1.2 vs. 0.5 +/- 0.2 pmol/L (P < 0.001); stimulated, 6.8 +/- 2.3 vs. 2.3 +/- 1.0 pmol/L (P < 0.001); nonsuppressible, 1.3 +/- 0.7 vs. 0.2 +/- 0.08 pmol/L (P < 0.001)]; PTH-(1-84) values were similar (basal, 3.1 +/- 1.2 vs. 2.0 +/- 0.6 pmol/L; stimulated, 12.0 +/- 3.9 vs. 15.5 +/- 6.6 pmol/L; nonsuppressible, 1.1 +/- 0.6 vs. 0.52 +/- 0.22 pmol/L). Thus, a non-(1-84) PTH molecular form detected by two-site I-PTH assays accumulates in renal failure and accounts for a larger proportion of I-PTH than that in normal subjects. Levels of I-PTH 1.57 times higher than those in normocalcemic subjects are thus required in renal failure to achieve similar PTH-(1-84) concentrations. The composition of I-PTH is also identical in all hemodialyzed patients.

Hypocalcemia induced during major and minor abdominal surgery in humans.

Hypocalcemia has only been rarely reported during surgical procedures not involving massive blood transfusions. The frequent observation in our hospital of a low serum ionized calcium level during surgery in nonacutely ill patients prompted us to investigate the calcium-PTH axis in three groups of subjects undergoing major (hepatectomy; n = 10), moderately severe, or minor surgery under general anesthesia (colectomy; n = 7, herniorrhaphy; n = 9) compared to that in one group of minor surgery cases under epidural anesthesia (herniorrhaphy; n = 15). Serum samples were obtained before anesthesia, after anesthesia but before surgery, and 40 and 120 min after the beginning of surgery in all groups of patients and for up to 3 days in major and moderately severe cases. Significant falls (P < 0.01), always proportional to the severity of the surgical/anesthesia procedure, were observed for ionized calcium (6-20%), total calcium (8-19%), and albumin (8-23%) accompanied by increases in intact PTH (105-635%). The decrease in ionized and total calcium correlated with a decrease in albumin (P < 0.001). Phosphorus, pH, and magnesium levels remained within the normal range. Adjustment of ionized calcium for variation in albumin revealed that 50-100% of the variation in ionized calcium could be attributed to a fall in albumin resulting from fluid administration to patients before admission to the surgery ward and between the onset of anesthesia and the end of surgery (1.2-5.6 L). Albumin- and pH-independent residual ionized calcium decreases of 12.2% in the hepatectomy group, 4.6% in the group of moderately severe and minor cases under general anesthesia, and 3.7% in the control group reflected the severity of the surgical/anesthesia procedure.

The set point of parathyroid hormone stimulation by calcium is normal in progressive renal failure.

An increased set point of PTH stimulation by ionized calcium (Ca++) has been observed in renal failure patients with severe secondary hyperparathyroidism. The extension of this concept to all renal failure patients has remained problematic, even if it could explain elevated PTH levels in the absence of other biochemical abnormalities. We were particularly interested in seeing whether the concept could fit patients with progressive renal failure (PRF). To achieve this, we studied 26 normals (N), 9 patients with PRF, and 12 hemodialyzed patients (HD) in the basal state and during parathyroid function tests. The latter two groups were studied at the end of winter and end of summer, respectively. Patients with PRF had normal levels of Ca++, PO4, and 1,25(OH)2D, and they had low-normal concentrations of 25(OH)D; their basal I- and C-PTH levels were 3- and 4-fold higher than N, as were their creatinine levels. HD had significantly lower levels of Ca++ and 1,25(OH)2D, and they had higher levels of phosphate, creatinine, I-PTH, and C-PTH than N or PRF. Stimulated levels of I-PTH were similar in N (13.6 +/- 4.3 pmol/L) and PFR (18 +/- 3.3 pmol/L) and elevated in HD (37.1 +/- 28.7 pmol/L; P < 0.001 vs. N, and P < 0.05 vs. PRF). Nonsuppressible I-PTH was increased 2-fold in PRF (N = 0.64 +/- 0.19 vs. PRF = 1.28 +/- 0.46 pmol/L; P < 0.01) and 6-fold in HD (3.95 +/- 2.85 pmol/L; P < 0.001 vs. others). But the set point of I-PTH stimulation by Ca++ was normal in PRF (N = 1.18 +/- 0.03 vs. PRF = 1.20 +/- 0.04 mmol/L; not significant) and decreased in HD (1.09 +/- 0.04 mmol/L; P < 0.001 vs. others). Similar results were obtained with the set point of C-PTH and of the C-PTH/I-PTH ratio. A positive correlation was observed between serum Ca++ concentration and the set point value when all three populations were analyzed together (r = 0.759, n = 47, P < 0.0001). These results indicate that the set point of PTH stimulation is normal in PRF and decreased in hypocalcemic HD. The set point seems to adjust to the ambient Ca++ concentration of the patients, by mechanisms yet to be elucidated. This does not suggest participation of this factor to the genesis of the secondary hyperparathyroidism of PRF.

Acebutolol and hydrochlorothiazide in essential hypertension.

Acebutolol (ABL) and hydrochlorothiazide (HCT) were compared in patients with mild to moderate essential hypertension and low or normal peripheral renin activity. ABL reduced mean supine blood pressure from 151/97 to 140/87 mm Hg and HCT reduced the mean supine blood pressure from 153/98 to 143/92 mm Hg. ABL reduced heart rate from 73 to 67 beats/min; during HCT therapy it rose from 74 to 77 beats/min. Although the same proportion of patients achieved normal diastolic pressures with ABL (11/19) and with HCT (10/19), tension-time indices were lower during ABL than during HCT therapy. The average daily dose was 621 mg of ABL and 168 mg of HCT. Stimulated peripheral renin activity increased with HCT and was the same or lower with ABL. ABL did not induce adverse effects on serum potassium or uric acid. ABL was as effective in lowering blood pressure HCT but induced larger reductions in tension-time index as a result of the lowerered heart rate.

Screening for neuroblastoma is ineffective in reducing the incidence of unfavourable advanced stage disease in older children.

Neuroblastoma exhibits many characteristics which would suggest that preclinical detection may improve outcome. The Quebec Neuroblastoma Screening Project was initiated to determine whether mass screening could reduce mortality in a large cohort of infants. All 476,603 children born in the province of Quebec during a 5-year period of time (1 May 1989 to 30 April 1994) were eligible for determinations of urinary catecholamine metabolites at 3 weeks and 6 months of age. Children with positive screening were referred to one of four paediatric cancer centres in Quebec for uniform evaluation and treatment. Standardised incidence ratios (SIRs) were calculated for neuroblastoma in Quebec and two comparable population-based controls during the same period of time using similar ascertainment procedures. Compliance with screening in Quebec was 91% at 3 weeks (n = 425,816) and 74% at 6 months (n = 349,706). Up to 31 July 1995 with a follow-up of the birth cohort of 15-75 months, 118 cases of neuroblastoma were diagnosed, 43 detected preclinically by screening, 20 detected clinically prior to screening at 3 weeks of age and 55 detected clinically after 3 weeks of age having normal screens (n = 52) or never screened (n = 3). Based on data from concurrent control populations, 54.5 cases of neuroblastoma would have been expected in Quebec during the study period for an SIR of 2.17 (95% CI 1.79-2.57, P < 0.0001). For the two control groups, the overall SIR was 1.00 (NS). SIRs for Quebec by age at diagnosis in yearly intervals show a marked increased incidence under 1 year of age (SIR = 2.85, 95% CI 2.26-3.50), with no reduction in incidence in subsequent years. We conclude that screening for neuroblastoma markedly increases the incidence in infants without decreasing the incidence of unfavourable advanced stage disease in older children. It is unlikely that screening for neuroblastoma in infants will reduce the mortality of this disease.

Adaptation of parathyroid function to intravenous 1,25-dihydroxyvitamin D3 or partial parathyroidectomy in normal dogs.

Parathyroid function was studied in 14 normal dogs 1 month before and after daily i.v. administration of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) (eight dogs), or about 50% parathyroidectomy (six dogs), to test the hypothesis that degradation of newly synthesized intact parathyroid hormone (I-PTH) is involved in parathyroid gland adjustment to a modified demand for I-PTH. Parathyroid function was studied through i.v. infusions of Na2EDTA and CaCl2 and measurement of ionized calcium (Ca2+), I-PTH and carboxyl-terminal PTH (C-PTH) at various time points. The C-PTH/I-PTH ratio was used as an index for change in the relative proportion of circulating C-PTH vs I-PTH, 1 month prior to and following each intervention. This ratio was further validated by looking at the HPLC profile of I- and C-PTH in hypo- and hypercalcemia under experimental conditions. Basal Ca2+ was unaltered 1 month after surgery, and was maintained constant in the 1,25-(OH)2D3-treated group by gradually decreasing 1,25-(OH)2D3 doses over time from 0.25 to 0.13 microgram twice daily during the last week of the experimental protocol. In this same group, basal 1,25-(OH)2D3 was increased by 65% (P < 0.0001) and basal I-PTH was decreased by 40% (P < 0.05), while basal C-PTH and the C-PTH/I-PTH ratio remained unchanged. Stimulated and non-suppressible I- and C-PTH followed the same pattern with, this time, an increase of stimulated and non-suppressible C-PTH/I-PTH ratio of 60% (P < 0.05) and 85% (P < 0.05) respectively. There was no change in basal I-PTH, C-PTH, or C-PTH/I-PTH ratio after surgery. However, stimulated I- and C-PTH were decreased by 45% (P < 0.005) and 65% (P < 0.005) respectively, with a 30% (P < 0.005) decrease of stimulated C-PTH/I-PTH ratio. There was no change in non-suppressible I-PTH, while non-suppressible C-PTH decreased by 55% (P < 0.005), with a 55% (P < 0.05) decrease in non-suppressible C-PTH/I-PTH ratio. The HPLC profiles of I- and C-PTH obtained in hypo- and hypercalcemia disclosed a similar distribution of the immuno-reactivity into peaks before and after i.v. administration of 1,25-(OH)2D3 as well as partial parathyroidectomy. This indicated that C-PTH/I-PTH ratio changes were related to different circulating levels of I- and C-PTH rather than to a different composition of I- and C-PTH. These data indicate a shift in the circulating PTH profile toward more PTH carboxyl-terminal fragments after 1 month of i.v. 1,25-(OH)2D3, but toward more intact PTH 1 month after about 50% parathyroidectomy, possibly reflecting adjustments in PTH degradation induced by a modified demand for I-PTH. Although these changes are most likely modulated at the parathyroid gland level, we cannot formally eliminate participation of the hormone's peripheral metabolism.

Origin of parathyroid hormone (PTH) fragments detected by intact-PTH assays.

BACKGROUND: Intact parathyroid hormone (I-PTH) assays react with non-(1-84)PTH, large carboxyl-terminal (C) fragments with a partially preserved amino-terminal (N) structure. They account for up to 50% of I-PTH in renal failure and may be implicated in PTH resistance. We wanted to know if they were secreted by the parathyroid glands and generated by peripheral metabolism of PTH(1-84). METHODS: Anesthetized normal and nephrectomized (NPX) rats were injected i.v. with 1.5 microg human (h) PTH(1-84). Blood was obtained from 8 rats at 2, 4, 6, 8, 12, 24, 48 and 96 min. I-PTH (Allegro I-PTH) was measured in all samples. Pools of serum were fractionated by HPLC at each time point and the fractions assayed to quantitate hPTH(1-84) and non-(1-84)PTH. Secretion studies were performed with dispersed cells from 5 parathyroid adenomas. The serum of 10 patients with primary hyperparathyroidism and cell supernatants were fractionated by HPLC and were analyzed as described. RESULTS: hPTH(1-84) disappeared from serum biexponentially. The half-life of the first exponential was similar in normal (2.08 min) and NPX (1.94 min) rats, while that of the second was longer in NPX rats (32.4 vs 20.9 min). The residual quantity of hPTH(1-84) under the curve was greater in NPX (6964+/-2392 pmol) than in normal rats (3229+/-561 pmol; P<0.001). Non-(1-84)PTH concentration was maximal at 8 min in both groups and was higher in NPX (92.8+/-13.8 pmol/l) than in normal rats (38.8+/-7.2 pmol/l; P<0.01). The area under the curve of non-(1-84)PTH was also greater in NPX (1904+/-405 pmol) than in normal rats (664+/-168 pmol; P<0.001). All parathyroid adenomas secreted non-(1-84)PTH. It represented 21.1+/-3.9% of secreted and 32.5+/-1.3% of circulating I-PTH in primary hyperparathyroidism. CONCLUSIONS: Non-(1-84)PTH, like other C-PTH fragments, originates from both the peripheral metabolism of hPTH(1-84) and from parathyroid gland secretion. Renal failure influences its concentration by increasing the amount of substrate available and by reducing non-(1-84)PTH clearance. Its higher proportion in serum relative to cell supernatants in primary hyperparathyroidism reflects the added role of peripheral metabolism and the longer half-life of fragments.

Merits of adding a beta blocker (acebutolol) to a diuretic (hydrochlorothiazide) in the treatment of hypertension.

In a double-blind crossover study, the antihypertensive effect of hydrochlorothiazide alone and in combination with the beta blocker acebutolol was assessed in 18 patients suffering from mild to moderate hypertension. After a placebo period, the patients were placed on hydrochlorothiazide alone for four weeks at a dose of 50 mg daily. Acebutolol was than gradually titrated into the regimen until the optimum dose was established. The average dose was 555 mg per day, with the usual optimum dose 200 mg b.i.d. The patients then entered the crossover portion of the trial during which patients received either hydrocholorothiazide with acebutolol or hydrochlorothiazide with placebo. Each treatment period lasted six weeks. Blood pressure and heart rate were significantly lower with the combination treatment than with hydrochlorothiazide alone. At the end of each treatment period, the mean diastolic blood pressure (erect) was 90.5 mm Hg with hydrochlorothiazide-acebutolol but remained above 100 mm Hg with the diuretic alone. Neither hydrochlorothiazide nor acebutolol produced any significant changes in plasma renin activity or plasma aldosterone. There were very few side effects and no reports of bradycardia.

Normal parathyroid function with decreased bone mineral density in treated celiac disease.

Decreased bone mineral density (BMD) has been reported in patients with celiac disease in association with secondary hyperparathyroidism. The present study investigated whether basal parathyroid hormone (PTH) remained elevated and whether abnormalities of parathyroid function were still present in celiac disease patients treated with a gluten-free diet. Basal seric measurements of calcium and phosphate homeostasis and BMD were obtained in 17 biopsy-proven patients under treatment for a mean period of 5.7+/-3.7 years (range 1.1 to 15.9). In addition, parathyroid function was studied with calcium chloride and sodium citrate infusions in seven patients. Basal measurements of patients were compared with those of 26 normal individuals, while parathyroid function results were compared with those of seven sex- and age-matched controls. Basal results were similar in patients and controls except for intact PTH (I-PTH) (3.77+/-0.88 pmol/L versus 2.28+/-0.63 pmol/L, P<0.001), which was higher in the former group but still within normal limits. Mean 25-hydroxy vitamin D and 1,25-dihydroxy vitamin D values were normal in patients. Parathyroid function results were also found to be similar in both groups. Compared with a reference population of the same age (Z score), patients had significantly lower BMDs of the hip (-0.60+/-0.96 SDs, P<0.05) and lumbar spine (-0.76+/-1.15 SDs, P<0.05). T scores were also decreased for the hip (-1.3+/-0.9 SDs, P<0.0001) and lumbar spine (-1.4+/-1.35 SDs, P<0.0001), with two to three patients being osteoporotic (T score less than -2.5 SDs) and seven to eight osteopenic (T score less than -1 SDs but greater than or equal to -2.5 SDs) in at least one site. Height and weight were the only important determinants of BMD values by multivariate or logistical regression analysis in these patients. The results show higher basal I-PTH values with normal parathyroid function in treated celiac disease. Height and weight values are, but I-PTH values are not, an important determinant of the actual bone mass of patients. Normal parathyroid function in treated patients suggests a lack of previous severe secondary hyperparathyroidism and/or complete adaptation to prior changes in parathyroid function.