Sensitivity of Different ACTH and Cortisol Concentration Values in Corticotropin-Releasing Hormone Based Tests in Cushing's Disease

PURPOSE

In Cushing's disease (CD) patients, the aim of the present study is to confirm sensitivity of several ACTH and cortisol concentration values in different time points, during corticotropin-releasing hormone (CRH) stimulation test and during CRH stimulation following dexamethasone suppression (DEX-CRH) test.

METHODS

We retrospectively analyzed cortisol and ACTH concentration increment during CRH and DEX-CRH tests in 23 patients with confirmed CD. Cortisol and ACTH concentrations were determined immediately before, 15 min and 30 min after CRH stimulation. We evaluated the sensitivity of different cutoff values including those reported in previous studies, in the diagnosis of CD.

RESULTS

During DEX-CRH test, 15 min serum cortisol concentration of 1.4 μg/dl (38 nmol/L) had a sensitivity of 90.9%, and serum cortisol concentration ≥1.27 μg/dl (35 nmol/L) had a sensitivity of 100%. For plasma ACTH, sensitivity of 100% was obtained using ACTH ≥3.5pmol/L (16 pg/ml) at 30 min. During CRH test, 35% increase from baseline in ACTH concentration had a sensitivity of 72.7%. Twenty percent increase in cortisol 30 minutes after stimulation yielded a sensitivity of 85.7%. The best sensitivity of ACTH and cortisol increment was obtained 15 min after stimulation, using 19% and 9% increase, respectively (sensitivity of 100% and 92.8%, respectively).

CONCLUSION

During CRH and DEX-CRH tests, the study findings agree with the good sensitivity of ACTH and cortisol cutoff values suggested in previous studies; yet, other cutoff values may give a higher diagnostic sensitivity.

The correlation between testosterone, inflammation and cytokine status in type-2 diabetes men

Type 2 diabetes mellitus (T2DM) is believed to cause hypogonadism through increasing pro-inflammatory cytokines. Tumour necrosis factor-α (TNF-α) is a primary cytokine associated with T2DM. The study explored the association between total testosterone (TT) level and cytokines status in 53 adult males, 27 T2DM (T2DM group) and 26 non-T2DM (control group). Blood samples evaluated fasting plasma glucose, HbA1c, insulin, HOMA-IR, FSH, LH, TT, prolactin, estradiol, cortisol, cortisol-binding globulin, C-reactive protein and eight cytokines (Interferon-gamma, IL-10, IL-13, IL-17A, IL-4, IL-23, IL-6, TNF-α). Data are presented as a median with interquartile interval. TT concentration was lower in the T2DM group [10.9 nmol/L (7.1-12.2) vs. 12.3 nmol/L (10.7-14.9) in control, p = 0.008]. CRP and cortisol in T2DM patients were higher than in control (p = 0.031 and 0.041 respectively). TT was negatively correlated with HOMA-IR, body mass index (BMI) and FSH (p = 0.028, 0.019 and 0.006 respectively). Multiple linear regression models showed that lower TT values were predictable by a linear combination of the independent variables: TNF-α, BMI and T2DM (p = 0.047, 0.023 and 0.019 respectively). High CRP and cortisol levels in T2DM patients suggest an inflammatory state. TT levels associated with TNF-α suggest a role of this cytokine in the aetiology of hypogonadism in T2DM patients.

Performance of low-dose cosyntropin stimulation test in the afternoon

BACKGROUND

Earlier research on 1 μg low-dose test (LDT) performed using 20.3 cm plastic IV tubing on healthy volunteers, has shown that afternoon testing was associated with a sevenfold increased likelihood of failing the test. Nevertheless, it has been claimed that subnormal cortisol response using plastic tubes might have resulted from cosyntropin adherence to the tube and, thus, loss of the delivered dosage. Following from our previous study, which showed that using a short (2.5 cm) plastic tube does not alter in-vitro-cosyntropin dosage delivery or healthy-volunteers' morning cortisol responses, we predicted that, when using the same short plastic tube, LDT would show comparable morning and afternoon cortisol stimulation. The current study was designed to investigate this prediction by comparing morning and afternoon cortisol responses in healthy volunteers during LDT, using a short plastic tube.

METHODS

Thirteen healthy adult volunteers were recruited for the study. Each subject underwent morning and afternoon LDT via 25 mm plastic intravenous line tube. Baseline serum cortisol (SC) in addition to SC and salivary free cortisol (SFC) 30-minute responses were determined.

RESULTS

Mean baseline morning SC concentration was higher in the morning than in the afternoon (13.63±3.42 and 9.18±2.78 μg/dL, respectively; P<0.001); however, mean absolute SC-concentration increment between baseline and 30-minute time point was higher in the afternoon than in the morning (11.89±3.50 and 7.71±3.12 μg/dL, respectively; P=0.002). Subsequently, LDT resulted in comparable morning and afternoon 30-minute SC (21.33±3.08 and 21.08±3.43 μg/dL, respectively; P=0.782) and SFC concentration (0.939±0.256 and 1.036±0.372 μg/dL, respectively; P=0.463).

CONCLUSIONS

In healthy volunteers, using a 2.5 cm plastic tube, LDT provides comparable morning and afternoon 30-minute stimulated SC and SFC concentration.

Performance of low-dose cosyntropin stimulation test handled via plastic tube

PURPOSE

Studies on 1 μg low-dose test showed that among 1 μg cosyntropin samples pushed through long IV plastic tubing, some adrenocorticotropic hormone dosage was not recovered, and in healthy volunteers it provided subnormal cortisol responses. The aim of the current study is to assess whether there is any loss in adrenocorticotropic hormone 1-24 concentration when pushed through a short plastic tube, and to assess serum and salivary cortisol responses in low-dose test among healthy volunteers, using a similar short plastic tube vs. direct intravenous consyntropin injection.

METHODS

We evaluated in vitro if adrenocorticotropic hormone was absorbed in a 2.5 cm plastic tube by measuring adrenocorticotropic hormone 1-24 concentration in a 1 μg/ml adrenocorticotropic hormone aliquot solution before and after being flushed through the plastic tube. For the in vivo study, we recruited 20 healthy adult volunteers. Each subject underwent low-dose test via 2.5 cm plastic tube via plastic tube and via direct intravenous injection by a metal syringe via direct intravenous injection, and cortisol responses were determined.

RESULTS

Mean adrenocorticotropic hormone 1-24 concentration did not differ significantly when flushed via plastic tube or measured in the aliquot solution (P = 0.25). In vivo, mean 30-min serum cortisol concentrations were 20.47 ± 2.87 and 21.62 ± 3.89 μg/dl in via plastic tube and in via direct intravenous injection tests, respectively, and did not show a significant difference (P = 0.16).

CONCLUSIONS

In low-dose test, using a 2.5 cm plastic tube ensures completeness of the intravenous adrenocorticotropic hormone injection dosage and provides equivalent cortisol responses.

Tensile forces applied on a cell-embedded three-dimensional scaffold can direct early differentiation of embryonic stem cells toward the mesoderm germ layer

Mechanical forces play an important role in the initial stages of embryo development; yet, the influence of forces, particularly of tensile forces, on embryonic stem cell differentiation is still unknown. The effects of tensile forces on mouse embryonic stem cell (mESC) differentiation within a three-dimensional (3D) environment were examined using an advanced bioreactor system. Uniaxial static or dynamic stretch was applied on cell-embedded collagen constructs. Six-day-long cyclic stretching of the seeded constructs led to a fourfold increase in Brachyury (BRACH-T) expression, associated with the primitive streak phase in gastrulation, confirmed also by immunofluorescence staining. Further examination of gene expression characteristic of mESC differentiation and pluripotency, under the same conditions, revealed changes mostly related to mesodermal processes. Additionally, downregulation of genes related to pluripotency and stemness was observed. Cyclic stretching of the 3D constructs resulted in actin fiber alignment parallel to the stretching direction. BRACH-T expression decreased under cyclic stretching with addition of myosin II inhibitor. No significant changes in gene expression were observed when mESCs were first differentiated in the form of embryoid bodies and then exposed to cyclic stretching, suggesting that forces primarily influence nondifferentiated cells. Understanding the effects of forces on stem cell differentiation provides a means of controlling their differentiation for later use in regenerative medicine applications and sheds light on their involvement in embryogenesis.

A possible analytical and clinical role of endogenous antibodies causing discrepant adrenocorticotropic hormone measurement in a case of ectopic Cushing’s syndrome

Heterophilic antibodies are well described, but poorly appreciated interferents and is often not a recognized problem affecting most immunoassays. We report a patient presented with ectopic Cushing’s syndrome (CS), but repeated plasma adrenocorticotropic hormone (ACTH) concentrations conducted by immunoassay were inappropriately within the reference range and not elevated, most probably as a result of antibody interference. A 36-year-old woman, presented with large gastric neuroendocrine carcinoma and severe ectopic CS, while repeated plasma ACTH concentrations conducted by immunoassay were inappropriately within the reference range. As we expected ACTH concentration to be higher, we performed several tests to evaluate whether there was any assay interference causing falsely lower than expected ACTH results. We measured ACTH using a different immunoassay, assayed the sample in dilution, assayed the sample after being incubated in heterophilic antibody blocking agent tube and performed recovery studies. Tests indicated the presence of interfering compounds, most probably heterophilic antibodies. When clinicians find ACTH concentrations to be lower than expected, we recommend the laboratory investigate antibody interference.

Hemodynamic Forces as a Stimulus for Arteriogenesis

Ischemic heart diseases put a heavy economical burden on Western society. They remain one of the major causes of morbidity, and preventive or postoperative treatments are lengthy and expensive. In some patients of ischemic heart diseases, there is not a direct correlation between the degree of occlusion of major arteries and the development of medical symptoms or damage to the heart function. Interestingly, these patients develop well-formed collateral vessels that compensate for the decrease in blood supply to the heart wall. Clearly, the ability to understand why and how these patients develop collateral vessels may serve as a base for a new strategy to treat ischemic heart diseases by promoting collateral formation. The current article summarizes recent advances in the understanding of how collateral vessels develop and offers the authors' point of view on the central role of biomechanical forces in this process and the molecular mechanisms that underline it.

Transcriptional and post-translation regulation of the Tie1 receptor by fluid shear stress changes in vascular endothelial cells

The interaction between the vascular endothelium and hemodynamic forces (and more specifically, fluid shear stress), induced by the flow of blood, plays a major role in vascular remodeling and in new blood vessels formation via a process termed arteriogenesis. Tie1 is an orphan tyrosine kinase receptor expressed almost exclusively in endothelial cells and is required for normal vascular development and maintenance. The present study demonstrates that Tie1 expression is rapidly down-regulated in endothelial cells exposed to shear stress, and more so to shear stress changes. This down-regulation is accompanied by a rapid cleavage of Tie1 and binding of the cleaved Tie1 45 kDa endodomain to Tie2. The rapid cleavage of Tie1 is followed by a transcriptional down-regulation in response to shear stress. The activity of the Tie1 promoter is suppressed by shear stress and by tumor necrosis factor alpha. Shear stress-induced transcriptional suppression of Tie1 is mediated by a negative shear stress response element, localized in a region of 250 bp within the promoter. The rapid down-regulation of Tie1 by shear stress changes and its rapid binding to Tie2 may be required for destabilization of endothelial cells in order to initiate the process of vascular restructuring.