Parvalbumin is reduced in the peripheral nerves of diabetic rats.

Parvalbumin (PA), one of the Ca2+-binding neuronal marker proteins, has been revealed to exist in the myelinated axons of the posterior root of the spinal cord and the peripheral nerve of rats. To investigate the role of PA for the genesis of diabetic neuropathy, the levels of PA in the sciatic nerve of normal and streptozotocin-induced diabetic rats were measured by radioimmunoassay (RIA) for PA. The immunohistochemical distribution of PA in the sciatic nerve from both groups was also studied. The RIA for PA revealed that the levels of PA in the sciatic nerve of diabetic rats were significantly decreased when compared with those of normal rats. However, the contents of S-100 protein, another type of Ca2+-binding glial marker protein, did not show any significant difference in the sciatic nerve from both groups. Immunohistochemically, the amount of PA containing myelinated axons of the diabetic nerve was markedly decreased when compared with nondiabetic subjects. These results suggest that the decreased level of PA in the peripheral nerve might contribute to the genesis of diabetic neuropathy.     

Altered responsiveness to thyrotropin in thyroid slices of Graves' disease preoperatively treated with excess iodide.

In a previous paper, we demonstrated that the acute administration of excess iodide inhibits the adenylate cyclase-cAMP system in mouse thyroid lobes. In the present study, we examined whether presurgical therapy with stable iodide reduces the responsiveness to TSH in thyroid tissues from patients with Graves' disease. Eight patients with Graves' disease were presurgically treated with methimazole and stable iodide and six were given methimazole alone. Normal tissues from five patients with thyroid nodules were also tested. We have found that stimulation by TSH (5 and 50 mU/ml) of cAMP formation in thyroid slices from patients preoperatively treated with methimazole and iodide is significantly less than in slices from patients treated with methimazole alone. Similar observations were also made with other thyroid stimulators, such as prostaglandin E2 and 4-methylhistamine. Furthermore, thyroid slices from patients treated with methimazole alone responded to TSH to the same degree as slices of normal tissues. The data suggest that one of the reasons for the hyporesponsiveness to TSH in thyroids from patients with Graves' disease is preoperative treatment with stable iodide.     

Rqh1 blocks recombination between sister chromatids during double strand break repair, independent of its helicase activity

Many questions remain about the process of DNA double strand break (DSB) repair by homologous recombination (HR), particularly concerning the exact function played by individual proteins and the details of specific steps in this process. Some recent studies have shown that RecQ DNA helicases have a function in HR. We studied the role of the RecQ helicase Rqh1 with HR proteins in the repair of a DSB created at a unique site within the Schizosaccharomyces pombe genome. We found that DSBs in rqh1(+) cells, are predominantly repaired by interchromosomal gene conversion, with HR between sister chromatids [sister-chromatid conversion (SCC)], occurring less frequently. In Deltarqh1 cells, repair by SCC is favored, and gene conversion rates slow significantly. When we limited the potential for SCC in Deltarqh1 cells by reducing the length of the G2 phase of the cell cycle, DSB repair continued to be predominated by SCC, whereas it was essentially eliminated in wild-type cells. These data indicate that Rqh1 acts to regulate DSB repair by blocking SCC. Interestingly, we found that this role for Rqh1 is independent of its helicase activity. In the course of these studies, we also found nonhomologous end joining to be largely faithful in S. pombe, contrary to current belief. These findings provide insight into the regulation of DSB repair by RecQ helicases.     

Immunization with human thyrotrophin receptor peptide induces an increase in thyroid hormone in rabbits.

Eight rabbits were immunized with a synthetic peptide corresponding to the unique N-terminal region (termed N peptide; amino acid residues 29-57) in the extracellular domain of the human thyrotrophin (TSH) receptor. After 10 weeks, all of the eight rabbits produced anti-N peptide antibodies. Western blot analysis revealed that the antibodies recognized rabbit TSH receptor as an approximately 100 kDa protein. We compared the level of thyroid hormone in serum taken before immunization (preimmune sera) with that of serum taken after immunization (postimmune sera) in these immunized rabbits. Postimmune sera from the eight rabbits had higher mean (+/- S.D.) levels of tri-iodothyronine (T3) and thyroxine (T4) than did preimmune sera (T3, preimmune 0.82 +/- 0.26 micrograms/l vs postimmune 1.33 +/- 0.35, P < 0.01; T4, preimmune 33.7 +/- 10.0 micrograms/l vs postimmune 41.0 +/- 6.0, P < 0.05). T3 levels in four rabbits and T4 levels in four rabbits after immunization were over the normal range obtained from six age-matched control rabbits. Seven rabbits exhibited thyroid-stimulating antibody (TSAb) activity with various degrees (241-545%). The concentration of T3 and T4 did not increase over 10 weeks in either non-immunized rabbits (T3, preimmune 0.89 +/- 0.34 micrograms/l vs postimmune 0.82 +/- 0.22; T4, preimmune 31.1 +/- 7.3 micrograms/l vs postimmune 30.3 +/- 5.1) or other peptide-immunized rabbits (T3, preimmune 0.68 micrograms/l (n = 2) vs postimmune 0.69; T4, preimmune 33.1 micrograms/l vs postimmune 26.4). These results indicate that experimentally produced anti-TSH receptor antibody with TSAb activity induces an increase in thyroid hormone in rabbits.     

The role of cyclic adenosine 3',5'-monophosphate and polyol metabolism in diabetic neuropathy.

The effects of a stable prostacyclin analog, Iloprost, and aldose reductase inhibitors (ONO-2235 and isoliquiritigenin) were studied to elucidate the role of cAMP in diabetic neuropathy in relation to polyol metabolism. In in vivo experiments, the cAMP and myoinositol contents in sciatic nerves and motor nerve conduction velocity were significantly reduced in diabetic rats. Iloprost significantly restored the reduced cAMP content in sciatic nerves and improved motor nerve conduction velocity in diabetic rats. However, the contents of sorbitol or myoinositol in sciatic nerves were not affected by Iloprost in diabetic rats. On the other hand, aldose reductase inhibitors significantly reduced the sorbitol content and increased the cAMP and myoinositol contents in the sciatic nerves of diabetic rats. The motor nerve conduction velocity was also slightly but significantly improved by treatment with aldose reductase inhibitors. There was a negative correlation between cAMP and sorbitol in the sciatic nerves of diabetic rats treated with aldose reductase inhibitors and a positive correlation between cAMP and motor nerve conduction velocity. In in vitro experiments, Iloprost significantly increased cAMP, but did not affect the sorbitol content in sciatic nerves. Aldose reductase inhibitors inhibited sorbitol accumulation and increased cAMP in sciatic nerves. Our data suggest that polyol pathway activation somehow results in cAMP reduction in sciatic nerves and that the reduction of cAMP in peripheral nerves may be closely related to the pathogenesis of diabetic neuropathy.     

Amyotrophic lateral sclerosis and neurosarcoidosis: A case report

Amyotrophic lateral sclerosis (ALS) remains a clinical diagnosis without definable biomarkers. The pathomechanism of motor neuron degeneration in ALS has yet to be elucidated. Here we present a case of limb‐onset ALS, with autopsy findings of Bunina bodies and skein‐like inclusions, as well as sarcoid granulomas predominating among motor neurons. The targeting of the motor neurons by the sarcoid inflammation raises questions regarding the role of cellular immunity in the pathomechanisms for ALS. Muscle Nerve, 2009     

The regulation of two distinct glucose transporter (GLUT1 and GLUT4) gene expressions in cultured rat thyroid cells by thyrotropin.

We investigated the glucose transporter mRNAs expressed in FRTL5, a rat thyroid cell line, and their regulation by TSH by means of the polymerase chain reaction. FRTL5 cells as well as rat thyroid tissue expressed three types of glucose transporter mRNAs: GLUT1 or erythrocyte/HepG2/brain isoform, GLUT2 or pancreatic beta-cell/liver isoform, and GLUT4 or muscle/fat isoform. GLUT1 mRNA predominated, GLUT4 mRNA was minor, and GLUT2 mRNA expression was faint. Incubation of FRTL5 cells with TSH induced a time- and concentration-dependent increase in GLUT1 mRNA levels, while GLUT4 mRNA levels were decreased. The response of GLUT1 mRNA to TSH was evident at 3 h, and the maximal response was achieved at 12 h. TSH at a dose of 1 mU/ml elicited an approximately 3-fold increase in GLUT1 mRNA levels. (Bu)2cAMP (1 mM), 8-bromo-cAMP (1 mM), and forskolin (50 microM) mimicked the effect of TSH on GLUT1 and GLUT4 mRNA levels. The increase in GLUT1 mRNA by TSH was correlated with the increase in GLUT1 protein and the increase in 2-deoxyglucose transport activity. These observations suggest that in thyroid cells, TSH stimulates glucose transport at least in part by enhancing GLUT1 gene expression, and that the effect of TSH on GLUT1 and GLUT4 mRNA levels is mediated by a cAMP-dependent pathway.