Biomedical subjects

Marie-Christine Vantyghem

Publications and source records attributed to Marie-Christine Vantyghem.

10 recordsLinked to original sources

PubMed2006

A PRKAR1A mutation associated with primary pigmented nodular adrenocortical disease in 12 kindreds.

CONTEXT: Primary pigmented nodular adrenocortical disease (PPNAD), a rare cause of corticotropin-independent Cushing syndrome, can be part of Carney complex (CNC), an autosomal dominant multiple neoplasia syndrome characterized by spotty skin pigmentation, cardiac myxomas, and endocrine tumors or be isolated (i). Germline PRKAR1A-inactivating mutations have been observed in both CNC and iPPNAD, but with no apparent genotype-phenotype correlation. OBJECTIVE: The objectives of the study were a detailed phenotyping for CNC manifestations in 12 kindreds bearing the same PRKAR1A mutation and a study of the consequences of the mutation and a potential founder effect. DESIGN: The study consisted of descriptive case reports. SETTING: The study was conducted at two referral centers. PATIENTS: The patients described in this study were referred for PRKAR1A gene mutation analysis because of a diagnosis of apparently iPPNAD. RESULTS: We describe a 6-bp polypyrimidine tract deletion [exon 7 IVS del (-7-->-2)] in 12 unrelated kindreds that were referred for Cushing syndrome due to PPNAD. Nine of the patients had no family history; in two, there was a family history of iPPNAD. Only one patient met the criteria for CNC. Relatives carrying the same mutation had no manifestations of CNC or PPNAD, suggesting a low penetrance of this PRKAR1A defect. A founder effect was excluded by extensive genotyping of chromosome 17 markers. CONCLUSIONS: In conclusion, a small intronic deletion of the PRKAR1A gene is a low-penetrance cause of mainly iPPNAD; it is the first PRKAR1A genetic defect to have an association with a specific phenotype.

Adolescent↗

PubMed2006

Responses of the steroid circadian system to alcohol in humans: Importance of the time and duration of intake.

Reports provide conflicting data about the effects of alcohol consumption on the hormonal system. Any study of these effects must control for a number of variables, including sex, alcohol status (alcoholic addiction vs. non-addiction), medical status (malnutrition, liver disease), and conditions of alcohol exposure, including an acute or continuous pattern of intake. The latter appears to be an especially critical factor in interpreting these effects. The authors therefore conducted a trial with a circadian design in which alcohol was administered repeatedly and regularly over a 26 h period for a total dose of 256 g. Because this protocol involves continuous alcohol administration, it is similar to administration among alcoholics and thus sheds new light on alcohol's effect on hormone secretion. Using healthy volunteers rather than alcoholics, however, prevents any confounding due to liver disorders and nutritional deficiencies, and thus makes it possible to focus on the direct role of alcohol in hormonal modifications. In these conditions, the continuous administration of alcohol did not affect cortisol secretion, but serum testosterone levels were significantly higher at all time points during the alcohol session than at the corresponding time points during the control session. These data are not consistent with previously reported findings for the relation between alcohol and both cortisol and testosterone, because in the current experiment the action of ethanol on steroid secretion should involve the circadian clock more than the hormonal system itself.

Adolescent↗

PubMed2006

Phenotype and HFE genotype in a population with abnormal iron markers recruited from an Endocrinology Department.

OBJECTIVE: The aim of this study was to describe HFE genotype in a population of patients with altered iron markers recruited in an Endocrinology Department and to define the possible phenotype-genotype relationships. METHODS: A total of 156 patients with high serum ferritin concentrations (>300 ng/ml) or transferrin saturation (>45%) (I group), and a control group of 106 healthy subjects (C group) underwent HFE genotyping (classical C282Y and H63D mutations). We also examined the main genetic features of subgroups in I according to the presence (D) or the absence (ND) of diabetes. RESULTS: (1) The genotypes were significantly different in the I and C groups (P<0.001), with an increased frequency of major 282Y allele in the I group (35% vs 7.5%), but not of minor 63D allele (17 vs 18.5%). (2) The genotype of D and ND groups also differed (P<0.0001), with a lower frequency of C282 heterozygosity (P<0.0001) in the D group, and a higher prevalence of H63D heterozygosity in the D vs ND groups (P<0.01). (3) The phenotypic comparison of D and ND groups also showed a higher mean body mass index, age, and serum ferritin concentration, as well as an increased proportion of males with increased liver enzymes in the D group. CONCLUSION: This population harboring abnormal iron markers had a different HFE genotype and a higher 282Y allele frequency than the control population. This suggests that blood iron markers could be checked in etiological investigations of metabolic disturbances to identify patients who should undergo genotyping, since approximately 20% were diagnosed with C282Y homozygosity.

Adult↗

PubMed2005

Autosomal dominant resistance to thyrotropin as a distinct entity in five multigenerational kindreds: clinical characterization and exclusion of candidate loci.

CONTEXT: Resistance to TSH (RTSH) is an inherited disorder of variable hyposensitivity to TSH. The metabolic consequences can range from euthyroid hyperthyrotropinemia to severe congenital hypothyroidism with thyroid hypoplasia. Although subclinical and mild hypothyroidism fitting the RTSH phenotype is common in the population, the role of genetic factors is far from being understood. Only in rare cases has RTSH been attributed to TSHR or PAX8 gene mutations. OBJECTIVE, SETTING, AND PARTICIPANTS: Toward the identification of novel RTSH genes, we studied five large, unrelated families comprising 102 individuals, 56 of whom were affected. RESULTS: Inheritance of RTSH in these families followed an autosomal dominant pattern without evidence for incomplete penetrance, yet expressivity was variable. Considering only fully phenotyped generations, 64% of the progeny was affected, with a 1:1.4 male-to-female ratio. Of 18 affected individuals tested in the neonatal period, two were undetected because of borderline results. The thyroid phenotype was indistinguishable from that observed with PAX8 and TSHR defects. In four families, untreated affected subjects of all ages had elevated serum thyroglobulin levels, consistent with a defect in the thyroid follicle cells. Linkage of RTSH to TSHR and PAX8 was excluded in all five families. For the largest families, we likewise excluded a contribution of genes previously only associated with syndromic forms of RTSH, namely TITF1, GNAS, and FOXE1. CONCLUSIONS: These kindreds represent a distinct etiological entity of autosomal dominant RTSH. According to the clinical presentation of these families, genetic causes of mild hyperthyrotropinemia in the general population may be more common than currently appreciated.

DNA-Binding Proteins↗

PubMed2005

Viral protein VP4 is a target of human antibodies enhancing coxsackievirus B4- and B3-induced synthesis of alpha interferon.

Coxsackievirus B4 (CVB4)-induced production of alpha interferon (IFN-alpha) by peripheral blood mononuclear cells (PBMC) is enhanced in vitro by nonneutralizing anti-CVB4 antibodies from healthy subjects and, to a higher extent, from patients with insulin-dependent diabetes mellitus. In this study, we focused on identification of the viral target of these antibodies in CVB systems. High levels of IFN-alpha were obtained in supernatants of PBMC incubated with CVB4E2 or CVB3 and plasma from healthy subjects and, to a higher extent, from patients. The VP4 capsid proteins dissociated by heating at 56 degrees C from CVB4E2 (VP4(CVB4)) and CVB3 (VP4(CVB3)) but not H antigen preincubated with plasma from healthy subjects or patients inhibited the plasma-dependent enhancement of CVB4E2- and CVB3-induced IFN-alpha synthesis. There was no cross-reaction between VP4(CVB4) and VP4(CVB3) in the inhibiting effect. IFN-alpha levels in culture supernatants showed dose-dependent correlation with anti-VP4 antibodies eluted from plasma specimens using VP4-coated plates. There were higher index values for anti-VP4 antibodies detected by enzyme-linked immunosorbent assay (ELISA) and higher proportions of positive detection in 40 patients than in 40 healthy subjects (80% versus 15% for anti-VP4(CVB4)). There was no relationship between the levels of anti-CVB neutralizing antibodies and the detection of anti-VP4 antibodies by ELISA. The CVB plasma-induced IFN-alpha levels obtained in PBMC cultures in the anti-VP4 antibody-positive groups were significantly higher than those obtained in the anti-VP4 antibody-negative groups regardless of the titers of anti-CVB neutralizing antibodies. These results show that VP4 is the target of antibodies involved in the plasma-dependent enhancement of CVB4E2- and CVB3-induced IFN-alpha synthesis by PBMC.

Adult↗

PubMed2004

[Congenital hypomagnesemia].

MORE PRECISE IDENTIFICATION: The progress in molecular genetics has led to better understanding of primitive magnesium deficiency. Transporters of this cation have been identified in the intestines and kidneys. The majority of congential hypomanesemia phenotypes have been correlated with a defect in magnesium transport. The primary deficiency of intestinal absorption of magnesium is responsible for hypomagnesemia and subsequent hypocalcemia. DEPENDING ON THE MECHANISM: Magnesium absorption defects in Henle's loop induce hypomagnesemia with hypercalciuria and nephrocalcinosis, autosomal dominant hypocalcemia or Bartter syndrome. In isolated dominant hypomagnesemia and Gitelman syndrome, an abnormality in the distal convoluted tubule explains the primitive hypomagnesemia, through renal leaking. Conversely, the mechanisms of recessive isolated hypomagnesemia remains unknown. ORIENTING GENETIC DIAGNOSIS: In a context of primitive hypomagnesemia, the clinical and biological presentation will orient genetic research leading to correct diagnosis. However, there are many border-line phenotypes and the pheno-genotype correlation is still imperfect.

Absorption↗

PubMed2004

[Pseudo-hypoaldosteronisms].

TWO FORMS: Pseudohypoaldosteronisms (PHA) are characterized by end-organ resistance to aldosterone inducing hyperkalemia and hyperaldosteronism. There are two forms of PHA classified according to the level of blood pressure with either hypotension (Type 1 PHA or PHA 1) or hypertension (Type 2 PHA or PHA 2). PHA 1: The association with hypotension and high renin level (PHA 1) is responsible for type 4 tubular acidosis and should suggest congenital or acquired excessive salt loss. Acquired forms are associated with salt wasting of urinary (nephropathy) or digestive (colon resection + ileostomy) origin. Congenital neonatal forms are either sporadic or autosomal dominant or recessive. Sporadic or autosomal dominant forms are caused by mutations in the mineralocorticoid receptor gene and generally remit with age. Autosomal recessive forms are caused by mutations in the gene encoding the amiloride-sensitive sodium channel and are clinically more severe with pulmonary symptoms. PHA 2: The association of hyperkalemia/hyperaldosteronism with high blood pressure should suggest PHA 2 or Gordon's syndrome, still called familial hyperkalemic hypertension. This form of low-renin hypertension is caused by mutations in the WNK genes (WNK 1 for PHA 2C and WNK 4 for PHA 2B), but other genes located on different loci are also involved. These WNK kinases constitute a new signalisation pathway that would regulate blood pressure and homeostasy of Na+, K+, H+ and Cl- ions.

Blood Pressure↗

PubMed2004

Profile and outcome of pure androgen-secreting adrenal tumors in women: experience of 21 cases.

BACKGROUND: The aim of the study was to determine the outcome and possible prognostic factors of pure androgen-secreting adrenal tumors (PASATs). METHODS: In a review of 801 adrenal operations from 1970 through 2003, 21 women with PASATs were divided into 2 groups, benign and undetermined tumors (Weiss score < or = 3) (BT = 11) and malignant tumors (Weiss > or =4 or nonresectable) (MT = 10). RESULTS: In both groups, age at presentation was similar. There were no differences concerning type of secretion, but increase in testosterone level was 2.6-fold greater in malignant tumors (MT) than benign tumors (BT). Imaging studies allowed diagnosis of malignancy in 4 of 10 MT. Size and weight were greater for MT than for BT (average, 13.7 vs 9.2 cm and 1462 vs 206 g). At follow-up (median, 17 y; range, 1 to 33 y) 2 of 11 patients with BT died of unrelated causes, and 9 of 11 are alive without recurrence; 5 of 10 patients with MT died of disease, and 3 are alive with disease; 7 of those 8 patients had stage III or IV disease and/or had a Weiss score of 6 or greater. Two patients with MT are alive without disease; both were Weiss 7, stage II and received mitotane postoperatively. CONCLUSIONS: PASATs of undetermined benign condition share the good prognosis of BT. Weiss score is diagnostic of malignancy. MacFarlane classification determines the prognosis, and long-term disease-free survivors at stages III/IV are never observed after operation only. Postoperative mitotane therapy might be beneficial at stage II.

Adolescent↗

PubMed2004

Assessment of the severity of hypoglycemia and glycemic lability in type 1 diabetic subjects undergoing islet transplantation.

Currently, the major indications for solitary islet transplantation are recurrent severe hypoglycemia and labile glucose control. Quantifying these problems remains subjective. We have developed a scoring system for both hypoglycemia and glycemic lability, established normative data, and used them in patients who have undergone islet transplantation. A composite hypoglycemic score (HYPO score) was devised based on the frequency, severity, and degree of unawareness of the hypoglycemia. In addition, using 4 weeks of glucose records, a lability index (LI) was calculated based on the change in glucose levels over time and compared with a clinical assessment of glycemic lability. A mean amplitude of glycemic excursions (MAGE) was also calculated based on 2 consecutive days of seven readings each day. These scores were determined in 100 randomly selected subjects with type 1 diabetes from our general clinic to serve as a control group and in patients before and after islet transplantation. The mean age of the control diabetic subjects was 38.4 +/- 1.3 years (+/-SE), with a duration of diabetes of 21.5 +/- 1.1 years. The median HYPO score in the control subjects was 143 (25th to 75th interquartile range: 46-423). The LI in the diabetic control subjects was 223 (25th to 75th interquartile range: 130-329 mmol/l(2)/h.week(-1)). The LI correlated much more closely than the MAGE with the clinical assessment of lability. A HYPO score of > or = 1,047 (90th percentile) or an LI > or = 433 mmol/l(2)/h.week(-1) (90th percentile) indicated serious problems with hypoglycemia or glycemic lability, respectively. The islet transplant patients (n = 51) were 42.1 +/- 1.4 years old, with a duration of diabetes of 25.7 +/- 1.4 years. Islet transplant patients had a mean HYPO score of 1,234 +/- 184 pretransplant, which was significantly higher than that of the control subjects (P < 0.001), which became negligible posttransplantation with the elimination of hypoglycemia. The median LI pretransplant was 497 mmol/l(2)/h.week(-1) (25th to 75th interquartile range: 330-692), significantly higher than that of control subjects (P < 0.001), and fell to 40 (25th to 75th interquartile range: 14-83) within a month after the final transplant. In those who had lost graft function, the LI rose again. The HYPO score and LI provide measures of the extent of problems with hypoglycemia and glycemic lability, respectively, complement the clinical assessment of the problems with glucose control before islet transplantation, and will allow comparison of selection of subjects for transplants between centers.

Awareness↗

PubMed2002

Circulating and cell-bound antibodies increase coxsackievirus B4-induced production of IFN-alpha by peripheral blood mononuclear cells from patients with type 1 diabetes.

Increased levels of IFN-alpha have been found in patients with type 1 diabetes who have detectable levels of coxsackievirus B4 (CVB4) RNA in their blood. The IFN-alpha-inducing activity of CVB4 in vitro is weak but can be enhanced by human IgGs. Therefore, it was investigated in vitro whether a preferential IFN-alpha response of peripheral blood mononuclear cells (PBMCs) to CVB4 exists in patients with type 1 diabetes (n=56) compared with healthy subjects (n=20) and whether antibodies play a role. In patients, the levels of IFN-alpha obtained after stimulation by PBMCs with CVB4 were higher (P=0.008), an individual IFN-alpha response by PBMCs to CVB4 was more frequent (P=0.0004) and increased levels of IFN-alpha were observed in CVB4-infected whole blood cultures. The IFN-alpha-inducing activity of patients plasma and IgGs mixed with CVB4 and then added to PBMCs was high in comparison with healthy subjects (P<0.001) and was inhibited by preincubating the cells with anti-FcgammaRII, anti-FcgammaRIII and anti-CAR (coxsackievirus and adenovirus receptor) antibodies. The strong IFN-alpha responsiveness of PBMCs to CVB4 suggested that IgGs bound to the cell surface might play a role. A short 56 degrees C incubation of PBMCs from patients responsive to CVB4 generated supernatants, which, when added to cells, exhibited IFN-alpha-enhancing activity in combination with CVB4, whereas those of controls did not. Specific antibodies for FcgammaRI, FcgammaRII and CAR inhibited this activity. These studies demonstrate that CVB4, through interactions with circulating and/or cell-bound IgGs, can strongly induce the production of IFN-alpha by PBMCs from patients with type 1 diabetes.

Adenoviridae↗