Insulin-degrading enzyme higher in subjects with metabolic syndrome.

Metabolic syndrome (MS) is comprised of a cluster of abnormalities in glucose, lipid, and vascular homeostasis, which is most commonly linked to abdominal obesity. MS heralds increased risk for development of diabetes and is linked to impairment in insulin signaling. Insulin-degrading enzyme (IDE) is one of the mechanisms through which insulin blood levels are maintained. It has been previously suggested that controlling IDE levels could provide yet another potential therapeutic approach in diabetes. Here we aim to investigate whether changes in serum IDE levels correlate with the severity of MS. Using a highly sensitive ELISA assay of active IDE in human serum, we found a strong correlation between circulating IDE levels and circulating levels of triglycerides, insulin, and c-peptide and an inverse correlation with HDL cholesterol (HDLc). Serum IDE levels were higher in MS subjects than in control subjects. Hence, circulating IDE may serve as a tool to identify subjects with abnormal insulin metabolism, possibly those with MS that are at risk to develop diabetes.

Two novel exonic point mutations in HEXA identified in a juvenile Tay-Sachs patient: role of alternative splicing and nonsense-mediated mRNA decay.

We have identified three mutations in the beta-hexoseaminidase A (HEXA) gene in a juvenile Tay-Sachs disease (TSD) patient, which exhibited a reduced level of HEXA mRNA. Two mutations are novel, c.814G>A (p.Gly272Arg) and c.1305C>T (p.=), located in exon 8 and in exon 11, respectively. The third mutation, c.1195A>G (p.Asn399Asp) in exon 11, has been previously characterized as a common polymorphism in African-Americans. Hex A activity measured in TSD Glial cells, transfected with HEXA cDNA constructs bearing these mutations, was unaltered from the activity level measured in normal HEXA cDNA. Analysis of RT-PCR products revealed three aberrant transcripts in the patient, one where exon 8 was absent, one where exon 11 was absent and a third lacking both exons 10 and 11. All three novel transcripts contain frameshifts resulting in premature termination codons (PTCs). Transfection of mini-gene constructs carrying the c.814G>A and c.1305C>T mutations proved that the two mutations result in exon skipping. mRNAs that harbor a PTC are detected and degraded by the nonsense-mediated mRNA decay (NMD) pathway to prevent synthesis of abnormal proteins. However, although NMD is functional in the patient's fibroblasts, aberrant transcripts are still present. We suggest that the level of correctly spliced transcripts as well as the efficiency in which NMD degrade the PTC-containing transcripts, apparently plays an important role in the phenotype severity of the unique patient and thus should be considered as a potential target for drug therapy.

The low-dose (1 microg) adrenocorticotropin stimulation test in kidney and kidney-pancreas transplant patients: a potential guideline for steroid withdrawal.

Chronic steroid treatment is known to impair the hypothalamic-pituitary adrenal axis (HPA) but the need to assess HPA function prior to withdrawal of steroid therapy in post-transplant patients has not been uniformly accepted. We evaluated the status of the HPA axis in 48 kidney or kidney-pancreas transplant patients who were considered for possible discontinuation of glucocorticoid therapy using a recently validated dynamic test of HPA integrity, the low-dose (1 microg) adrenocorticotropin (ACTH) test. HPA suppression was detected in 29 (60%) of the patients, four of which had severe hypoadrenalism prohibitive of steroid withdrawal. Neither the duration of steroid treatment nor 8:00 am serum cortisol was a useful marker of hypoadrenalism. 8:00 am cortisol in subjects with normal HPA reserve and subjects with partial hypoadrenalism overlapped considerably but levels <5 microg/dL were indicative of severe hypoadrenalism. Pre-withdrawal diagnosis of partial hypoadrenalism allowed the identification of subjects requiring no further steroid replacement under regular daily circumstances. However glucocorticoid supplementation was prescribed in the event of stress such as infection, exceptional effort, trauma or surgery. Individuals with partial HPA impairment, but not patients with severe HPA suppression, improved upon retesting 3 months later. Patients exhibiting normal response to 1 mcg ACTH enjoyed an uneventful course following steroid withdrawal. Since hypoadrenalism is extremely common in post-transplant patients, we recommend the use of the low-dose ACTH test as a convenient method to identify patients with various degrees of hypoadrenalism prior to steroid withdrawal.

Low-dose ACTH (1 microg) salivary test: a potential alternative to the classical blood test.

OBJECTIVES: Salivary cortisol is unaffected by cortisol binding globulin (CBG) and hence allows CBG-related variations in serum total cortisol to be bypassed. We assessed whether or not salivary cortisol can be used for the low-dose (1 microg) ACTH test in subjects with presumed normal and elevated levels of CBG. PATIENTS/METHODS: We measured serum and salivary cortisol responses to intravenous administration of 1 microg ACTH in 14 healthy volunteers, 14 'hyperoestrogenic' women [in their first or early second trimester of pregnancy, using oral contraceptives (OC) or on hormone replacement therapy (HRT)] and 10 patients with secondary hypoadrenalism. Cortisol levels were recorded before as well as 30 and 60 min (+30; +60 min) after ACTH administration. RESULTS: Baseline salivary cortisol did not differ significantly between the hypoadrenal and healthy patients (7.11+/-1.4 and 12.13+/-1.59 nmol/l; P=0.48) but there was a significant difference between hypoadrenal and hyperoestrogenic patients (18.94+/- 3.44 nmol/l; P=0.01). The largest difference between hypoadrenal patients and healthy individuals was observed at+30 min (9.16+/-2.8, 52.65+/-8.78 and 48.81+/- 6.9 nmol/l, in the hypoadrenal, healthy and hyperoestrogenic patients, respectively; P< 0.05). At this time-point values< 24.28 nmol/l were found in all hypoadrenal patients and cortisol levels >or= 27.6 nmol/l were found in 26 out of 28 healthy volunteers. ACTH-stimulated serum cortisol but not salivary cortisol was significantly higher in hyperoestrogenic women than in the healthy volunteers at either+30 or+60 min. CONCLUSIONS: The salivary low-dose ACTH test yields results that parallel the response of circulating cortisol to ACTH and may provide an alternative to the blood test, particularly in situations where increased CBG levels complicate the changes in serum cortisol levels.

Postoperative treatment of clinically nonfunctioning pituitary adenomas with dopamine agonists decreases tumour remnant growth.

OBJECTIVE: There is no consensus as to the optimal postoperative treatment of patients with clinically nonfunctioning pituitary adenomas (NFPA) in whom total tumour removal has not been achieved. In this study we assessed whether dopamine agonist (DA) treatment can prevent postoperative remnant enlargement in NFPA. DESIGN AND METHODS: Thirty-three patients (25 men/8 women; mean age, 61.7 +/- 11.2 years; mean follow-up, 40.6 +/- 4.8 months) were treated with DA, and their outcome was compared to that of 47 untreated patients (33 men/14 women; mean age, 59 +/- 2 years; mean follow-up, 42.9 +/- 4.2 months). RESULTS: Tumour mass decreased or remained stable in 18/20 patients in whom DA treatment was initiated upon detection of residual tumour on postoperative MRI (group I). In 13 subjects (group II), DA therapy was started when tumour remnant growth became evident during the course of routine follow-up. Tumour growth stabilized or decreased in 8/13 (61.5%) of these patients. In contrast, tumour size remained stable in only 38.3% (18/47) of the untreated subjects (P < 0.0001 for comparisons among the three groups) and increased in the remaining 29 patients. Tumour enlargement free mean survival time was 103.7 +/- 8.8 months (CI 86.3-121) for group I, 43.9 +/- 9.6 months (CI 25.2-62.8) for group II and 36.7 +/- 3.8 (CI 29.2-44.2) for the control group (P = 0.0017). Treatment vs. control hazard ratio for tumour enlargement was 0.135 for group I (P = 0.007, 95% CI 0.032-0.577) and 0.892 for group II (P = 0.817; 95% CI 0.34-2.34). CONCLUSIONS: Dopamine agonist therapy is associated with a decreased prevalence of residual tumour enlargement in patients with nonfunctioning pituitary adenomas, particularly when treatment is instituted before tumour remnant growth is detected.