Measurement uncertainty of 25-OH vitamin D determination with different commercially available kits: impact on the clinical cut offs

SUMMARY

Due to "measurement uncertainty", the "true" 25-OH vitamin D (25(OH)D) of a patient (whatever the commercially available assay tested) will be >80 nmol/L if its measured concentration is >100 nmol/L. Thus, if a physician considers that a normal VTD status is a 25(OH)D level >or=80 nmol/L, he should ensure that the patient's results are >or=100 nmol/L.

INTRODUCTION

Many experts recommend that serum levels of 25(OH)D should be above a lower normal limit of 75-80 nmol/L. However, the value delivered by laboratories is only an estimation of the "true" value due to "measurement uncertainty." When using a cut off, measurement uncertainty around the cut off is important because therapeutic actions may differ if the measured value is below or above the limit. We aimed to establish the "measurement uncertainty" at different levels of concentration for several commercially available 25(OH)D analytical techniques.

METHODS

We constituted three pools of serum with different 25(OH)D concentrations. Each pool was assayed in triplicate during 5 days with the DiaSorin RIA, Liaison, Elecsys, and Chromsystems-HPLC assays.

RESULTS

We report a relatively high "measurement uncertainty" for the measurement of 25(OH)D for the four different techniques: the mean relative uncertainties, all techniques confounded were 19.4%, 16.0%, and 11.3% for pool 1 (35.3 nmol/L), pool 2 (79.5 nmol/L), and pool 3 (126.1 nmol/L), respectively.

CONCLUSIONS

Our results show that, whatever the assay, the "true" 25(OH)D of a patient will be >80 nmol/L if its measured concentration is >100 nmol/L. In other words, if a physician considers that a normal VTD status is defined by a 25(OH)D level >or=80 nmol/L, he should ensure that the patients present a 25(OH)D >or=100 nmol/L.

Novel molecular profiles of endometrial cancer-new light through old windows

Endometrial carcinoma (EC) is the most common gynecological malignancy in the western world. A widely accepted dualistic model, which has been established on a morphological basis, differentiates EC into two broad categories: Type I oestrogen-dependent adenocarcinoma with an endometrioid morphology and Type II non-oestrogen-dependent EC with a serous papillary or clear cell morphology. Molecular genetic evidence indicates that endometrial carcinoma, as described in other malignancies, likely develops as the result of a stepwise accumulation of alterations in cellular regulatory pathways, such as oncogene activation and tumor suppressor gene inactivation, which lead to dysfunctional cell growth. These molecular alterations appear to be specific in Type I and Type II cancers. In type I endometrioid endometrial cancer, PTEN gene silencing in conjunction with defects in DNA mismatch repair genes, as evidenced by the microsatellite instability phenotype, or mutations in the K-ras and/or beta-catenin genes, are recognized major alterations, which define the progression of the normal endometrium to hyperplasia, to endometrial intraepithelial neoplasia, and then on to carcinoma. In contrast, Type II cancers show mutations of TP53 and Her-2/neu and seem to arise from a background of atrophic endometrium. Nevertheless, despite the great effort made to establish a molecularly-based histological classification, the following issues must still be clarified: what triggers the tumor cells to invade the myometrium and what causes vascular or lymphatic dissemination, finally culminating in metastasis? RUNX1, a transcription factor, was recently identified as one of the most highly over-expressed genes in a microarray study of invasive endometrial carcinoma. Another candidate gene, which may be associated with an initial switch to myometrial infiltration, is the transcription factor ETV5/ERM. These studies, as well as those conducted for other genes possibly involved in the mitotic checkpoint as a major mechanism of carcinogenesis in non-endometrioid endometrial cancer, could help in understanding the differences in the biology and the clinical outcome among histological types.

Molecular determinants of invasion in endometrial cancer

Endometrial carcinoma is the most common gynaecological malignancy in the western world and the most frequent among infiltrating tumours of the female genital tract. Despite the characterisation of molecular events associated with the development of endometrial carcinoma, those associated with the early steps of infiltration and invasion in endometrial cancer are less known. Deep myometrial invasion correlates with more undifferentiated tumours, lymph-vascular invasion, node affectation and decreased global survival. In this review we present an overview of the molecular pathology of myometrial infiltration that defines the initial steps of invasion in endometrial cancer. Down-regulation of E-cadherin as a main player of epithelial to mesenchymal transition, as well as modifications on other molecules involved in cell-cell contacts, render cells with a migratory phenotype. In addition, altered signalling pathways and transcription factors associate with myometrial invasion, histologic grade and metastasis.

Retroperitoneal hematoma compressing a single functioning kidney: an unusual cause of obstructive renal failure

We report a case of a retroperitoneal hematoma occurring in a patient under anticoagulation therapy for deep-venous thrombosis and presenting as an anuric acute renal failure. A coexisting polycythemia vera led to misdiagnosis that could have been life-threatening. A woman, known for polycythemia vera and a single functioning right kidney, was admitted with mild abdominal pain in a context of recent deep venous thrombosis under low-molecular weight heparin. Clinical examination revealed hepatomegaly associated with polycythemia vera. Biochemical evaluation disclosed an acute renal failure, and renal ultrasonography showed no dilation of the renal pelvis. Retroperitoneal hematoma resulted in shock, progressive anemia and obstructive renal failure, related to renal pelvic compression. A right renal indwelling catheter was introduced to restore urine flow after one hemodialysis session, and an inferior vena cava filter was placed because of anti-coagulation contra-indication. However, pulmonary embolism occurred, so that oral anticoagulants were introduced. The hematoma resorbed spontaneously, and a year after this episode, the patient is still alive and well. Retroperitoneal hematoma is a rare cause of obstructive acute renal failure and a life-threatening complication of anti-coagulation therapy.

Hostility and helper T-cells in patients with bulimia nervosa

OBJECTIVE

The study aimed to analyze the correlation between lymphocyte counts and several psychopathological variables associated with psychological instability (depression, hostility, impulsivity, self-defeating personality traits, and borderline personality symptoms) in patients with bulimia nervosa (BN).

METHOD

Sixty BN patients were assessed, using specific scales for eating pathology, general psychopathology, impulsivity, depression, and borderline personality features. Lymphocyte and lymphocyte subset counts were performed. Plasma cortisol at 8:00, before and after administration of 1 mg of dexamethasone at 23:00, was determined. The influence of body weight, and the use of tobacco, alcohol, and caffeine was controlled. The relationship between each isolated variable and the number of immune cells was analyzed. In a second step, supplementary post-hoc analysis of the variables was introduced to confirm the accuracy of the psychopathological assessment.

RESULTS

Hostility was negatively correlated with the number of helper T-cells (CD4+). Patients with high hostility had lower CD4+ cell counts and lower CD4+/CD8+ ratios. In the post-hoc control study, hostility was significantly related with other "interpersonal" items.

CONCLUSIONS

These results support the idea that hostility, as an expression of disturbed interpersonal relationships, could play a role as a modulator of immune activity in patients with BN.

Inter-method variability in PTH measurement: implication for the care of CKD patients

The National Kidney Foundation/Kidney-Dialysis Outcome Quality Initiative guidelines recommend to maintain the serum intact parathyroid hormone (PTH) concentration between 150 and 300 ng/l in chronic kidney disease (CKD) stage 5 patients. As these limits were derived from studies that used the Allegro intact PTH assay, we aimed to evaluate whether they were applicable to other PTH assays. We compared the PTH concentrations measured with 15 commercial immunoassays in 47 serum pools from dialysis patients, using the Allegro intact PTH assay as the reference. We also evaluated the recovery of graded amounts of synthetic 1-84 and 7-84 PTH added separately to a serum pool. Although the assays were highly correlated, the concentrations differed from one assay to another. The median bias between the tested assays and the Allegro intact PTH assay ranged from -44.9 to 123.0%. When the PTH concentrations were 150 or 300 ng/l with the Allegro intact PTH assay, they ranged with other assays from 83 to 323 ng/l and from 160 to 638 ng/l, respectively. The tested assays recognized 7-84 PTH with various cross-reactivities, whereas a given amount of 1-84 PTH was recovered differently by these assays. We found important inter-method variability in PTH results owing to both antibody specificity and standardization reasons. The unacceptable consequence is that opposite therapeutic attitudes may be reached in a single patient depending on the PTH assay used. We propose to use assay-specific decision limits for CKD patients, or to apply a correcting factor to the PTH results obtained with a given assay.

Molecular pathology of endometrial carcinoma: transcriptional signature in endometrioid tumors

A dualistic model, which has been established on a morphological basis and that differentiates type I endometrioid from type II non-endometrioid endometrial cancer, is widely accepted. Molecular genetics have provided us with data supporting the dualistic model of endometrial tumorigenesis and with some clues to speculate about the sequence of the molecular alterations defining the tumorigenesis pathways. In type I endometrioid endometrial cancer, PTEN gene silencing, microsatellite instability associated with defects in DNA mismatch repair genes, or mutations in the K-ras gene are the known major alterations defining the progression from normal endometrium to hyperplasia and then on to carcinoma. Recently, cDNA microarray technology for identifying the differences in gene expression patterns between the histological types of endometrial cancer have permitted the identification of differentially expressed genes that could help us to understand differences in the biology and the clinical outcome between histiotypes. Genes involved in the mitotic checkpoint as a major mechanism of carcinogenesis in non-endometrioid endometrial cancer, or altered genes associated with the initial steps of myometrial infiltration in endometrioid endometrial cancer, represent examples of how useful large genetic screenings can be for understanding the tumorigenesis process and the future directions in the molecular pathogenesis of endometrial cancer.

[Study of the renal acidification capacity in children diagnosed of idiopathic hypercalciuria]

OBJECTIVE

To study the capacity of renal acidification in a group of children diagnosed of idiopathic hypercalciuria.

PATIENT AND METHODS

36 children were studied, to those that were determined the pCO2 (UpCO2) maximum urinary with two different stimuli, acetazolamide and sodium bicarbonate (NaHCO3). At 33 of them, was performed an acidification test with frusemide stimulus. We studied a control group of 13 healthy children so much for the first one as the second tests and other 14 healthy children for the acidification test with frusemide.

RESULTS

In the tests performed with NaHCO3 and acetazolamide stimulus, they were not proven differences in the values of UpCO2 neither in the urinary concentration of HCO3- (UHCO3-) than control children. Nevertheless, the UpCO2 and the concentration of UHCO3- in the patients were significantly lower with acetazolamide with regard to the NaHCO3 stimulus. In the acidification test with frusemide, significantly lower values of titratable acid and ammonium were obtained than control children.

CONCLUSIONS

In children with idiopathic hypercalciuria, the capacity of secretion of H+ is normal, what is evidenced, especially, when studying the maximum UpCO2 after stimulus with NaHCO3. When diuretics are used as stimuli, exists more negative results that can be due to a certain partial resistance to the action of the same ones or to that are less potent to induce the secretion of H+.

[Purging behaviors and nutritional status in anorexia nervosa and bulimia nervosa]

AIMS

The aim of the study was to investigate whether the use of purgative methods in patients with eating disorders (anorexia nervosa [AN] and bulimia nervosa [BN]) could be capable of producing changes in the nutritional status of the patients.

SETTING AND PATIENTS

The group under study was composed of 184 female eating disordered outpatients. One hundred and sixteen patients (63.0%) fulfilled the DSM-IV diagnostic criteria for BN (90 purging type, 26 nonpurging type). Sixty eight patients (37.0%) fulfilled the DSM-IV criteria for the diagnosis of AN (48 restricting type, 20 binging-purging type).

METHODS

The assessment process included anthropometry (body circumferences and skinfold thickness) and body impedance analysis.

RESULTS

The two subgroups of AN patients significantly differed from each of the BN subgroups. From a nutritional point of view, some significant differences between the two DSM-IV subtypes of AN existed, but not between the purging type and the nonpurging type of BN.

CONCLUSIONS

The paper discusses the clinical significance of these findings. An alternative subtypification of AN patients is proposed: 1) restricting type [patients who control their food intake and do not purge]; 2) purging type [patient with true episodes of binging which are followed by purgative behaviors]; and 3) pseudopurging type [patients with subjective binging episodes who use purging methods].

[Randomized trials in the prevention of recurrent calcium oxalate stones]

Kidney stone, with or without lumbar pain, is a major health care problem because of its prevalence and cost for both the patient and the society. Although, surgical procedures are well known, medical treatment and recurrences prophylaxis are uncodified. Fifteen stone recurrence prevention studies have been reviewed, evaluating dietary intake and drugs. The most important factor is a daily diuresis of at least 2 liters. Calcium intake shouldn't be restricted, whereas oxalate, sodium, and protein intakes have to be limited. Hyper and normocalciuretic kidney stone formers improve their outcome with thiazide or indapamide treatment. Hyperuricosuria justifies allopurinol. Potassium citrate (without sodium) may decrease recurrence risk, even in patients without hypocitraturia.

[In contrast to captopril and enalapril, losartan does not increase mortality of gerbils after carotid ligation]

OBJECTIVE

To check wether the deleterious effect of enalaprilat administered before unilateral caroid ligation in the gerbil reported by Fernandez et al. (J Cardiovasc Pharmacol 1994; 24: 937) is not a molecule specific effect but an angiotensin converting enzyme inhibitor class effect.

DESIGN AND METHOD

Survival rate of gerbils (an animal with incomplete Willis hexagona) was measured after unilateral carotid ligation with preadministration (2 hours before by gavage) of saline (0.75 ml) (n = 37); losartan (20 mg/kg) (n = 37), enalaparil (10 mg/kg) (n = 37); a combination of losartan and enalapril at the same dose (n = 37); and of captopril (75 mg/kg) (n = 35).

RESULTS

The survival rate of the gerbils 72 hours after carotid ligation was 65% in control, 62% in losartan, 30% in enalapril, 32% in enalapril + losartan, and 32% in captopril groups. Statistical analysis (log rank test) of the Kaplan-Meier survival curves over 72 hours showed no difference between losartan and controls nor between the various groups treated with ACEI. However survival was significantly lower in the ACEI groups than in the group treated by losartan alone (p < 0.02) or controls (p < 0.02). Intraaortic mean arterial pressure was measured in 6 controls, 6 animals treated with losartan and 6 other treated with enalapril. It was comparable in the losartan and enalapril treated animals (65 +/- 2 mm Hg vs 64 +/- 2) but significantly lower than in the controls (77 +/- 2 mmHg) (p < 0.02).

CONCLUSIONS

In contrast to oral preadministration of enalapril and captopril that of losartan does not increase the mortality of the gerbil after unilateral carotid ligation in spite of the same decrease in systemic blood pressure. Although a lower mortality than in controls was not observed with losartan as in the princeps study of Fernandez, these data are consistent with the demonstration by this author that angiotensin II plays a critical protective role in acute ischemia probably by promoting collateral circulation recruitment through non-AT1 receptors stimulation.

Comparison between IgG and F(ab')(2) polyvalent antivenoms: neutralization of systemic effects induced by Bothrops asper venom in mice, extravasation to muscle tissue, and potential for induction of adverse reactions

Whole IgG and F(ab')(2) equine-derived polyvalent (Crotalinae) antivenoms, prepared from the same batch of hyperimmune plasma, were compared in terms of neutralization of the lethal and defibrinating activities induced by Bothrops asper venom, their ability to reach the muscle tissue compartment in envenomated mice, and their potential for the induction of adverse reactions. Both preparations were adjusted to the same potency against the lethal effect of B. asper venom in experiments involving preincubation of venom and antivenom. Then, "rescue" experiments were performed, i.e. antivenom was administered either intravenously or intramuscularly at various times after envenomation. IgG and F(ab')(2) antivenoms were equally effective in the neutralization of lethality, both being more effective when administered i.v. than after i.m. injection. Neutralization decreased as the time lapse between envenomation and treatment increased. No significant differences were observed in the ability of antivenoms to neutralize defibrinating activity of B. asper venom in experiments involving independent injection of venom and antivenoms. There was a much higher accumulation of equine antibodies in muscle tissue that had been injected with B. asper venom than in non-envenomated tissue, indicating that venom-induced microvessel damage probably favors a prominent and similar extravasation of both IgG and F(ab')(2) antibodies. This may explain the similar effectiveness of both types of antivenom in previously reported studies on the neutralization of venom-induced local tissue damage. Both IgG and F(ab')(2) antivenoms activate human complement in vitro and induce an anti-equine immunoglobulin response in mice, indicating that Fc removal per se does not eliminate the potential for inducing adverse reactions. However, IgG antivenom had higher anticomplementary activity and induced a stronger anti-immunoglobulin response than F(ab')(2) antivenom.

Experimental and theoretical studies of the d8-d10 interaction between Pd(II) and Au(I): bis(chloro[(phenylthiomethyl)diphenylphosphine]gold(I))- dichloropalladium(II) and related systems

The reaction between thioether phosphine gold(I) precursors such as [AuCl(Ph2PCH2SPh)], 1, or [Au(Ph2PCH2SPh)2]CF3SO3 and PdCl2(NCPh)2 affords the new compounds [(AuCl(Ph2PCH2SPh)2PdCl2], 2, and [AuPdCl2(Ph2PCH2SPh)2]CF3SO3, 3. The crystal structure of complex 2 has the sterically unhindered Pd(II) and Au(I) at a distance of 314 pm. Quasirelativistic pseudopotential calculations on [AuPdCl3(PH2CH2SH)(SH2)] models give short Au-Pd distances at the second-order Møller-Plesset (MP2) level and long Au-Pd distances at Hartree-Fock (HF) level. A detailed analysis of the Au-Pd interaction shows dominant dispersion, some ionic contributions, and no net charge transfer between the metals.

Study of renal metabolic disturbances related to renal lithiasis at school age in very-low-birth-weight children

We studied 34 asymptomatic children who were born with a very-low-birth-weight (VLBW) and had no perinatal history of acute renal failure nor treatment with furosemide. The study was done at preschool or school age, looking for echographic changes and renal tubular disturbances which are known to predispose to renal lithiasis. The results were compared with those of a control group of 18 children who had been born at term with a body weight >2,500 g. One or more renal tubular disturbances were found in 64.70% of the VLBW children. Most frequently found were decreased ammonium excretion in response to furosemide (38.23%), enhanced N-acetylglucosaminidase excretion (35.29%), hypercalciuria (26.47%), and hypocitraturia (23.53%). Echography revealed renal cortical hyperechogenicity (17.65%) and renal lithiasis (8.82 %) in some of the VLBW children. We found a significant positive correlation (r = 0.7) between the perinatal level of plasma phosphate and the total amount of H+ excreted in response to furosemide at preschool or school age. Because these renal tubular anomalies may be precursors of future lithiasis, and the renal function and echography tests are not invasive, we suggest that renal tubular function be measured and followed up in every VLBW child, particularly when perinatal hypophosphatemia has occurred.

Gastric adenocarcinoma in a patient with X-linked agammaglobulinaemia

Patients with primary immunodeficiencies are at high risk for developing haematological malignancies and, to a lesser degree, carcinoma. We report a patient with ascertained X-linked agammaglobulinaemia who developed a gastric carcinoma involving the distal part of the stomach associated with chronic atrophic gastritis and intestinal metaplasia. These latter conditions are considered to be precursor conditions and the role of chronic infections is likely. Patients with X-linked agammaglobulinaemia, as with other primary immunodeficiencies, could benefit from regular gastrointestinal evaluation, leading to early diagnosis and treatment of carcinoma.

[Vegetal foreign body in the airway: an unusual cause of hemoptysis in childhood. Clinical case]

Hemoptysis is an infrequent symptom in childhood and potentially life threatening. The most common causes in this age group are bronchiectasis secondary to cystic fibrosis, cardiovascular and pulmonary congenital anomalies and a miscellaneous group of causes including retained intrabronchial aspirated foreign bodies. We report a previously healthy 5-year-old girl with recurrent pneumonias associated with episodes of hemoptysis. She was admitted in our institution to investigate the persistence of hemoptysis. Based on clinical history, aspiration of a vegetal foreign body was postulated as the etiology and it was confirmed in the pathological examination after surgical exploration, with pulmonary lobe resection. The importance of a good history taking in pediatric hemoptysis is emphasized.

Heteropolynuclear complexes with the ligand Ph2PCH2SPh: theoretical evidence for metallophilic Au-M attractions

Addition of two equivalents of diphenylthiomethylphosphine (PPh2-CH2SPh) to the starting materials [Au(tht)2]A (tht = tetrahydrothiophene), AgCF3SO3, or [Cu(CH3CN)4]CF3SO3 produces the mononuclear derivatives [M(PPh2CH2SPh)2]A (M = Au, A = CF3SO3 (1a); M = Au, A = ClO4 (1b); M = Ag, A = CF3SO3 (4); M = Cu, A = CF3SO3 (5)) which are able to form the heterodinuclear complexes [AuM'(PPh2CH2SPh)2](CF3SO3)2 (M' = Ag (2), Cu (3)) with a P-Au-P environment. If the starting gold complex is [Au(C6F5)(tht)], reaction with the phosphine produces [Au(C6F5)-(PPh2CH2SPh)] (6) from which, by reaction with AgCF3SO3 or [Cu(CH3CN)4]CF3SO3, the "snake"-type linear complexes [Au2M(C6F5)2-(PPh2CH2SPh)2]CF3SO3 (M = Ag (7), Cu (8)) are obtained. If the silver starting complex is AgCF3CO2, reaction in a 1:1 ratio gives the tetranuclear complex [Au2Ag2(C6F5)2(PPh2CH2SPh)2-(CF3CO2)2] (9). When the molar ratio is 1:2 the trinuclear complex [AuAg2(C6F5) (CF3CO2)2(PPh2CH2SPh)] (10) is obtained. According to ab initio calculations, the presence of only one gold atom is enough to induce metallophilic attractions in the group congeners, and this effect can be modulated depending on the gold ligand.