A model of human neural networks reveals NPTX2 pathology in ALS and FTLD

Human cellular models of neurodegeneration require reproducibility and longevity, which is necessary for simulating age-dependent diseases. Such systems are particularly needed for TDP-43 proteinopathies1, which involve human-specific mechanisms2-5 that cannot be directly studied in animal models. Here, to explore the emergence and consequences of TDP-43 pathologies, we generated induced pluripotent stem cell-derived, colony morphology neural stem cells (iCoMoNSCs) via manual selection of neural precursors6. Single-cell transcriptomics and comparison to independent neural stem cells7 showed that iCoMoNSCs are uniquely homogenous and self-renewing. Differentiated iCoMoNSCs formed a self-organized multicellular system consisting of synaptically connected and electrophysiologically active neurons, which matured into long-lived functional networks (which we designate iNets). Neuronal and glial maturation in iNets was similar to that of cortical organoids8. Overexpression of wild-type TDP-43 in a minority of neurons within iNets led to progressive fragmentation and aggregation of the protein, resulting in a partial loss of function and neurotoxicity. Single-cell transcriptomics revealed a novel set of misregulated RNA targets in TDP-43-overexpressing neurons and in patients with TDP-43 proteinopathies exhibiting a loss of nuclear TDP-43. The strongest misregulated target encoded the synaptic protein NPTX2, the levels of which are controlled by TDP-43 binding on its 3' untranslated region. When NPTX2 was overexpressed in iNets, it exhibited neurotoxicity, whereas correcting NPTX2 misregulation partially rescued neurons from TDP-43-induced neurodegeneration. Notably, NPTX2 was consistently misaccumulated in neurons from patients with amyotrophic lateral sclerosis and frontotemporal lobar degeneration with TDP-43 pathology. Our work directly links TDP-43 misregulation and NPTX2 accumulation, thereby revealing a TDP-43-dependent pathway of neurotoxicity.

Erythropoietin levels in endocrinopathies

BACKGROUND

Erythropoietin (EPO) is an oxygenregulated hormone promoting the differentiation of erythroid progenitor cells. Apart fromhypoxia, few data is available about release by secretagogues including hormones.

AIM

To investigate EPO serum concentration in subjects with endocrine diseases.

MATERIAL AND METHODS

A retrospective study evaluating serumEPO concentrations in serumleftovers fromsubjects with various endocrine disorders.

RESULTS

EPO is not noticeably influenced by thyroid hormone or cortisol concentrations and the relationship with hemoglobin concentration is preserved. In acromegalic patients, the latter is lost but EPO is neither statistically influenced by GH/IGF-I. This may reflect a dual action of GH and/or IGF-I on erythroid progenitors proliferation as well as on EPO synthesis.

CONCLUSION

EPO is not noticeably modified by endocrine disorders although GH and or IGF-I may alter EPO relationship with blood hemoglobin concentration.

[Surgical excision of subclinical cortisol secreting incidentalomas: Impact on blood pressure, BMI and glucose metabolism]

OBJECTIVES

To compare clinical, vascular and metabolic parameters before and after surgery in patients with subclinical cortisol secreting incidentalomas.

PATIENTS AND METHODS

Eight patients were investigated before and 12 months after removal of the mass on hemodynamic (blood pressure by MAPA procedure), anthropometric (body weight, body mass index), and metabolic parameters (glucose level, HbA(1c)).

RESULTS

In the whole group, 75% of patients displayed decrease in blood pressure (cessation of at least one hypotensive medication) and 33% of them were definitely cured of hypertension. Seventy-one percent of patients lost body weight and 37.5% lost more than 5%. In the whole group of patients, glucose level decreased by 1.1% and medical treatment was discontinuated in two of three diabetic patients.

CONCLUSION

Subclinical cortisol secreting adrenal incidentalomas are associated with cardiovascular risk factors that may be corrected after removal of the mass. Therefore, surgery may be an appropriate choice in patients with subclinical Cushing's syndrome to improve hypertension, body weight and impaired glucose level. Controlled studies comparing surgical treatment to a medical follow-up including optimal cardiovascular risk factors treatment are needed to define the usefulness of surgery in hypertensive patients with subclinical cortisol secreting incidentalomas.

Decreased expression of retinoid nuclear receptor (RAR alpha and RAR gamma) mRNA determined by real-time quantitative RT-PCR in peripheral blood mononuclear cells of hypothyroid patients

In vivo assessment of the cellular impact of thyroid hormones on target tissues might be of help for physiological studies and to evaluate the consequences of various diseases of the thyroid gland in humans. Given the tenuous relationship between retinoid and tri-iodothyronine (T3) status and that retinoids have also intracellular roles, the aim of this study was to determine the effect of hypothyroidism on the expression of T3 nuclear receptors (TR) and retinoic acid nuclear receptors (RAR, RXR) in human peripheral blood mononuclear cells (PBMC). Using real time RT-PCR, we quantified the relative amount of mRNA of the thyroid (TR alpha and TR beta) and retinoid (RAR alpha, RAR gamma, and RXR alpha) nuclear receptors in PBMC of euthyroid (n = 22) compared with hypothyroid (n = 22) subjects. Classical plasma parameters (free T3 (FT3), free thyroxine (T4) (FT4), thyroid-stimulating hormone (TSH), retinol (ROH), retinol-binding protein (RBP) and transthyretin (TTR)) were also measured. In hypothyroid subjects, the concentration of TSH was elevated, and dramatically low T3 and T4 concentrations were associated with a decrease in the expression of TR beta. Expression of RAR alpha and RAR gamma significantly decreased in hypothyroid versus control subjects, while an increased concentration of ROH was emphasised by hypothyroidism. These results first indicated that primary hypothyroidism induces hypoactivation of the retinoid nuclear pathway in PBMC, which was not predicted by the plasma ROH level. Further investigations will be necessary to evaluate these parameters in very small changes in thyroid hormone production such as mild (subclinical) hypothyroidism.

Fat distribution in obese women is associated with subtle alterations of the hypothalamic-pituitary-adrenal axis activity and sensitivity to glucocorticoids

OBJECTIVES

Obesity with abdominal body fat distribution (A-BFD) and hypothalamic-pituitary-adrenal (HPA) axis activity are somehow linked, but the exact interactions still need clarification. Obese subjects display normal circulating plasma cortisol concentrations with normal circadian rhythms. However, when the HPA axis is pharmacologically challenged, body fat distribution matters and then A-BFD obese women differ from those with subcutaneous body fat distribution (P-BFD). We hypothesized that lower dose provocative and suppressive tests than those used to diagnose hypercortisolism of tumour origin or adrenal insufficiency would shed some light on the characteristics of the HPA axis activity in relation with body fat distribution.

PATIENTS AND METHODS

Fifty premenopausal obese women were grouped according to their body fat mass distribution. Their plasma cortisol responses to (i) two low doses of dexamethasone (0.25 and 0.5 mg) with (ii) low dose of the ACTH analogue tetracosactrin (1 microg) were assessed. Salivary cortisol was also determined during the ACTH test.

RESULTS

A-BFD differed from P-BFD women in terms of HPA axis responsiveness. They had comparatively: (i) increased nocturnal cortisol excretion (9.38 +/- 2.2 vs. 6.82 +/- 0.91 nmol/micromol creatinine, A-BFD vs. P-BFD, respectively, P = 0.03); (ii) increased salivary cortisol response to ACTH stimulation (1 microg) [salivary cortisol peak: 33.4 (14.1-129) vs. 28.5 (13.2-42.8) nmol/l; salivary AUC: 825 (235-44738) vs. 537 (69-1420) nmol/min/l; A-BFD vs. P-BFD, P = 0.04 for both]; and (iii) increased pituitary sensitivity to dexamethasone testing [postdexamethasone (0.25 mg) plasma cortisol levels: 163 (26-472) vs. 318 (26-652) nmol/l and postdexamethasone (0.5 mg) plasma cortisol levels: 26 (26-79) vs. 33 (26-402) nmol/l; A-BFD vs. P-BFD, P = 0.01 for both).

CONCLUSIONS

These data demonstrate differences in the HPA axis activity and sensitivity to glucocorticoids between obese women differing in their body fat distribution, with both enhanced negative and positive feedback in those with abdominal obesity. Several mechanisms may explain these differences: central vs. peripheral hypotheses. Thus, abdominal obesity does not appear to be linked solely to one pathophysiological hypothesis.

Lessons from an unpleasant surprise: a biochemical strategy for the diagnosis of pheochromocytoma

OBJECTIVE

To audit the performances of the analytes used in the diagnosis of pheochromocytoma and to present a graphical guideline to help the diagnosis.

DESIGN

A 5 year retrospective study.

SETTINGS

Laboratory and departments of a university hospital.

PARTICIPANTS

In-patients, suspected of bearing a pheochromocytoma, were investigated for urinary metanephrines and catecholamines (photometric method) and vanillylmandelic acid, fractionated catecholamines and metanephrines [high pressure liquid chromatography (HPLC) coupled to electrochemical detection (ED)] urinary excretion.

MAIN OUTCOME

Patients with a pheochromocytoma (24 out of 2003 patients) were diagnosed by the combination of normetanephrine and metanephrine determination.

RESULTS

All analytes but dopamine were significantly elevated in patients with a pheochromocytoma. The area under the receiver operating characteristics (ROC) curves were the highest for total metanephrines, normetanephrine and metanephrine determinations. Because of analytical interferences in the metanephrines determination, the normetanephrine and metanephrine performed better. It is noteworthy that all pheochromocytomas had either normetanephrine or metanephrine levels above their respective optimal threshold (sensitivity 100%). The best optimal threshold performance was reached by the mean of three daily samples. Total or fractionated catecholamines or vanillylmandelic acid were less accurate tools.

CONCLUSION

Amongst urinary tests, the combined use of HPLC/ED determination of normetanephrine and metanephrine seems the most effective screening strategy for the diagnosis of pheochromocytoma. The older total metanephrine photometric assay is grieved by analytical interferences.

Diabetes as a result of atypical anti-psychotic drugs--a report of three cases

AIMS

Atypical anti-psychotic drugs (APDs) are widely used in psychotic disorders refractory to conventional neuroleptic agents.

RESULTS

Three cases of new-onset diabetes are reported in Caucasian men who were on clozapine (one) or olanzapine (two) for 3-6 months. They had a distinct presentation: weight loss, ketosis (one ketoacidosis), severe hyperglycaemia requiring insulin therapy, and relative insulin deficiency as reflected by glucagon stimulatory tests. In all cases, insulin was stopped within 1 month after the APD was discontinued.

CONCLUSIONS

Novel APDs not only induce diabetes as a result of weight gain in predisposed patients, but can also lead to a reversible state of insulin deficiency, and sometimes ketoacidosis.

Composition of insulin-induced body weight gain in diabetic patients: a bio-impedance study

Although insulin is a well-known cause of body weight gain, it is not clear whether it is due to the accumulation of fat or lean mass. We performed a 3 months Body-Impedance Analysis follow-up in 72 diabetic patients in a wide range of insulin indications: insulin introduction in young inaugural type 1 diabetics (n = 12), late-onset type 1 (n = 12), type 2 affected by intercurrent diseases (n = 12) or microangiopathic complications (n = 12), type 2 with failure of oral antidiabetic agents (n = 12), and insulin withdrawal in type 2 (n = 12). In type 1 patients, insulin led to the most important weight gain, but it was fat-free, with a major benefit on HbA1C. Type 2 patients affected by intercurrent diseases or microangiopathic complications had a mild, also fat-free weight gain, with a clear benefit on HbA1C. In type 2 patients with failure of oral agents, HbA1C declined less, weight gain was intermedia, but predominantly fat, mirrored by a predominant fat loss in type 2 patients whose insulin was stopped (without significant change in HbA1C). Both fat and lean mass contributed to insulin-induced body weight gain, but a significant negative relationship existed between their respective evolution in our patients (r = -0.23, p < 0.05 by linear regression analysis between delta fat mass and delta lean mass). Insulin-induced body weight gain is not univocal: insulin restaures or protects lean mass in its less controversial indications, whereas it leads to fat accumulation in type 2 patients with isolated failure of oral agents.