Sensitive detection of hemodynamic failure during orthostatic stress in patients with diabetic polyneuropathy using a mini laser Doppler blood flowmeter.

Autonomic dysfunction in diabetes is serious but often underestimated. The purpose of this study was to evaluate hemodynamics within the important initial phase just after standing, which cannot be evaluated by conventional instruments for orthostatic hypotension. Earlobe blood flow (EBF), which indirectly reflects the blood pressure response on standing, was evaluated using a mini laser Doppler flowmeter during standing from the sitting position in 58 healthy controls and 56 diabetic patients categorized as without (11), mild (27), and advanced diabetic polyneuropathy (18). The response area of the EBF waveform within 30 seconds after standing was calculated. An increased response area indicates poor recovery of EBF. Response area increased significantly with the degree of neuropathy (P < .001 for linear trend). Orthostatic hypotension was detected in two patients in the mild neuropathy group. The present approach may be sensitive and practical for detecting autonomic dysfunction not detected with the conventional orthostatic test.

Predictive value of titer of GAD antibodies for further progression of beta cell dysfunction in slowly progressive insulin-dependent (type 1) diabetes (SPIDDM).

AIMS: Whether the titer of glutamic acid decarboxylase antibodies (GADAs), especially a low titer, is a marker of progression of beta cell dysfunction in patients with slowly progressive insulin-dependent (type 1) diabetes (SPIDDM) is unclear. MATERIALS AND METHODS: Patients were subdivided as follows: patients with high GADA titers [≥10 U/ml (≥180 WHO U/ml): high GADA] (group 1, n = 37); those with low GADA titers [<10 U/ml (<180 WHO U/ml): low GADA] (group 2, n = 33); those without GADA and with islet cell antibodies (ICA) (group 3, n = 8); those without both GADA and ICA and with insulinoma-associated antigen 2 antibodies (IA-2A) (group 4, n = 6). We also allocated 198 type 2 diabetic patients without any GADA, ICA or IA-2A as group 5. Serum C-peptide responses to annual oral glucose tolerance tests (OGTTs) were followed up for a mean of 107 months from entry. RESULTS: The proportion of patients progressing to an insulin-dependent state in groups 1, 2, 3 and 4 was significantly higher than in group 5. C-peptide responses in OGTTs of patients in groups 1 and 2 were decreased at a significantly higher rate than in group 5. Multivariate Cox proportional hazard analysis revealed that factors including high GADA, low GADA, onset age <45 years, duration of diabetes <24 months, body mass index (BMI) <22.0 kg/m2, low degree of preserved beta cell function and ICA were independent risk factors for progression to an insulin-dependent state. CONCLUSIONS: SPIDDM patients with low GADA titers have a significantly higher risk of progression to an insulin-dependent state than type 2 diabetic patients, suggesting that the presence of GADA, irrespective of the titer, is a hallmark of beta cell failure. Other risk factors for further progression to an insulin-dependent state in SPIDDM patients were ICA, onset age, duration of diabetes, BMI and residual beta cell function.

Activation of the RhoB signaling pathway by thyroid hormone receptor ß in thyroid cancer cells.

Thyroid hormone receptor (TR) mediates the crucial effects of the thyroid hormone (T3) on cellular growth, development, and differentiation. Decreased expression or inactivating somatic mutations of TRs have been found in human cancers of the liver, breast, lung, and thyroid. The mechanisms of TR-associated carcinogenesis are still not clear. To establish the function of TRß in thyroid cancer cell proliferation, we constructed a recombinant adenovirus vector, AdTRß, which expresses human TRß1 cDNA. Thyroid cancer cell lines in which TRß protein levels were significantly decreased as compared to intact thyroid tissues were infected with AdTRß and the function of TRß on cell proliferation and migration was analyzed. Ligand-bound TRß induced HDAC1 and HDAC3 dissociation from, and histone acetylation associated with the RhoB promoter and enhanced the expression of RhoB mRNA and protein. In AdTRß-infected cells, T3 and farnesyl transferase inhibitor (FTI)-treatment induced the distribution of RhoB on the cell membrane and enhanced the abundance of active GTP-bound RhoB. This RhoB protein led to p21-associated cell-cycle arrest in the G0/G1 phase, following inhibition of cell proliferation and invasion. Conversely, lowering cellular RhoB by small interfering RNA knockdown in AdTRß-infected cells led to downregulation of p21 and inhibited cell-cycle arrest. The growth of BHP18-21v tumor xenografts in vivo was significantly inhibited by AdTRß injection with FTIs-treatment, as compared to control virus-injected tumors. This novel signaling pathway triggered by ligand-bound TRß provides insight into possible mechanisms of proliferation and invasion of thyroid cancer and may provide new therapeutic targets for thyroid cancers.

Distinct cell clusters touching islet cells induce islet cell replication in association with over-expression of Regenerating Gene (REG) protein in fulminant type 1 diabetes.

BACKGROUND: Pancreatic islet endocrine cell-supporting architectures, including islet encapsulating basement membranes (BMs), extracellular matrix (ECM), and possible cell clusters, are unclear. PROCEDURES: The architectures around islet cell clusters, including BMs, ECM, and pancreatic acinar-like cell clusters, were studied in the non-diabetic state and in the inflamed milieu of fulminant type 1 diabetes in humans. RESULT: Immunohistochemical and electron microscopy analyses demonstrated that human islet cell clusters and acinar-like cell clusters adhere directly to each other with desmosomal structures and coated-pit-like structures between the two cell clusters. The two cell-clusters are encapsulated by a continuous capsule composed of common BMs/ECM. The acinar-like cell clusters have vesicles containing regenerating (REG) Iα protein. The vesicles containing REG Iα protein are directly secreted to islet cells. In the inflamed milieu of fulminant type 1 diabetes, the acinar-like cell clusters over-expressed REG Iα protein. Islet endocrine cells, including beta-cells and non-beta cells, which were packed with the acinar-like cell clusters, show self-replication with a markedly increased number of Ki67-positive cells. CONCLUSION: The acinar-like cell clusters touching islet endocrine cells are distinct, because the cell clusters are packed with pancreatic islet clusters and surrounded by common BMs/ECM. Furthermore, the acinar-like cell clusters express REG Iα protein and secrete directly to neighboring islet endocrine cells in the non-diabetic state, and the cell clusters over-express REG Iα in the inflamed milieu of fulminant type 1 diabetes with marked self-replication of islet cells.

Ligand-bound thyroid hormone receptor contributes to reprogramming of pancreatic acinar cells into insulin-producing cells.

One goal of diabetic regenerative medicine is to instructively convert mature pancreatic exocrine cells into insulin-producing cells. We recently reported that ligand-bound thyroid hormone receptor α (TRα) plays a critical role in expansion of the ß-cell mass during postnatal development. Here, we used an adenovirus vector that expresses TRα driven by the amylase 2 promoter (AdAmy2TRα) to induce the reprogramming of pancreatic acinar cells into insulin-producing cells. Treatment with l-3,5,3-triiodothyronine increases the association of TRα with the p85α subunit of phosphatidylinositol 3-kinase (PI3K), leading to the phosphorylation and activation of Akt and the expression of Pdx1, Ngn3, and MafA in purified acinar cells. Analyses performed with the lectin-associated cell lineage tracing system and the Cre/loxP-based direct cell lineage tracing system indicate that newly synthesized insulin-producing cells originate from elastase-expressing pancreatic acinar cells. Insulin-containing secretory granules were identified in these cells by electron microscopy. The inhibition of p85α expression by siRNA or the inhibition of PI3K by LY294002 prevents the expression of Pdx1, Ngn3, and MafA and the reprogramming to insulin-producing cells. In immunodeficient mice with streptozotocin-induced hyperglycemia, treatment with AdAmy2TRα leads to the reprogramming of pancreatic acinar cells to insulin-producing cells in vivo. Our findings suggest that ligand-bound TRα plays a critical role in ß-cell regeneration during postnatal development via activation of PI3K signaling.

Absorption of radionuclides from the Fukushima nuclear accident by a novel algal strain.

Large quantities of radionuclides have leaked from the Fukushima Daiichi Nuclear Power Plant into the surrounding environment. Effective prevention of health hazards resulting from radiation exposure will require the development of efficient and economical methods for decontaminating radioactive wastewater and aquatic ecosystems. Here we describe the accumulation of water-soluble radionuclides released by nuclear reactors by a novel strain of alga. The newly discovered green microalgae, Parachlorella sp. binos (Binos) has a thick alginate-containing extracellular matrix and abundant chloroplasts. When this strain was cultured with radioiodine, a light-dependent uptake of radioiodine was observed. In dark conditions, radioiodine uptake was induced by addition of hydrogen superoxide. High-resolution secondary ion mass spectrometry (SIMS) showed a localization of accumulated iodine in the cytosol. This alga also exhibited highly efficient incorporation of the radioactive isotopes strontium and cesium in a light-independent manner. SIMS analysis showed that strontium was distributed in the extracellular matrix of Binos. Finally we also showed the ability of this strain to accumulate radioactive nuclides from water and soil samples collected from a heavily contaminated area in Fukushima. Our results demonstrate that Binos could be applied to the decontamination of iodine, strontium and cesium radioisotopes, which are most commonly encountered after nuclear reactor accidents.