Impaired proliferative response of V alpha 24 NKT cells from cancer patients against alpha-galactosylceramide

Human invariant V alpha 24(+) NKT cells are a relatively new subpopulation of lymphocytes. It has been reported that V alpha 24 NKT cells are significantly involved in some human diseases. We have evaluated the number and function of V alpha 24 NKT cells in both healthy volunteers and cancer patients. In this study we found that V alpha 24 NKT cells in unfractionated PBMCs obtained from cancer patients did not respond efficiently to alpha-galactosylceramide (alpha-GalCer) in vitro. Thus, their proportion after stimulation with alpha-GalCer was smaller than that found in healthy volunteers. However, the cancer patients' V alpha 24 NKT cells retained cytotoxic activity against malignant target cells, and they could efficiently proliferate to alpha-GalCer when fractionated by sorting. Furthermore, we found that addition of G-CSF to the culture could restore the low proliferative response of V alpha 24 NKT cells from cancer patients. These results suggest that some functions of NKT cells in cancer patients are impaired, and this observation carries significant implications for immunotherapy-based cancer treatments.     

Mouse model of Prinzmetal angina by disruption of the inward rectifier Kir6.1

The inwardly rectifying K(+) channel Kir6.1 forms K(+) channels by coupling with a sulfonylurea receptor in reconstituted systems, but the physiological roles of Kir6.1-containing K(+) channels have not been determined. We report here that mice lacking the gene encoding Kir6.1 (known as Kcnj8) have a high rate of sudden death associated with spontaneous ST elevation followed by atrioventricular block as seen on an electrocardiogram. The K(+) channel opener pinacidil did not induce K(+) currents in vascular smooth-muscle cells of Kir6.1-null mice, and there was no vasodilation response to pinacidil. The administration of methylergometrine, a vasoconstrictive agent, elicited ST elevation followed by cardiac death in Kir6.1-null mice but not in wild-type mice, indicating a phenotype characterized by hypercontractility of coronary arteries and resembling Prinzmetal (or variant) angina in humans. The Kir6.1-containing K(+) channel is critical in the regulation of vascular tonus, especially in the coronary arteries, and its disruption may cause Prinzmetal angina.     

Mutagenicities of quinoline and its derivatives.

Quinoline, recently reported to be carcinogenic in rats [12], was mutagenic to Salmonella typhimurium tester strains TA100 and TA98 in the presence of the metabolic activation system S-9 mix. 2-Chloroquinoline, a non-carcinogen [12], was non-mutagenic with or without S-9 mix. 8-Hydroxyquinoline, which is t known to be carcinogenic, was mutagenic with S-9 mix to both bacterial strains. The mutagenicities of 17 other quinoline derivatives that are not known to be carcinogenic were tested, and 12 of these compounds were mutagenic.     

A novel GIP receptor splice variant influences GIP sensitivity of pancreatic beta-cells in obese mice

Gastric inhibitory polypeptide (GIP) is an incretin that potentiates insulin secretion from pancreatic beta-cells by binding to GIP receptor (GIPR) and subsequently increasing the level of intracellular adenosine 3',5'-cyclic monophosphate (cAMP). We have identified a novel GIPR splice variant in mouse beta-cells that retains intron 8, resulting in a COOH-terminal truncated form (truncated GIPR). This isoform was coexpressed with full-length GIPR (wild-type GIPR) in normal GIPR-expressing tissues. In an experiment using cells transfected with both GIPRs, truncated GIPR did not lead to cAMP production induced by GIP but inhibited GIP-induced cAMP production through wild-type GIPR (n = 3-4, P < 0.05). Wild-type GIPR was normally located on the cell surface, but its expression was decreased in the presence of truncated GIPR, suggesting a dominant negative effect of truncated GIPR against wild-type GIPR. The functional relevance of truncated GIPR in vivo was investigated. In high-fat diet-fed obese mice (HFD mice), blood glucose levels were maintained by compensatory increased insulin secretion (n = 8, P < 0.05), and cAMP production (n = 6, P < 0.01) and insulin secretion (n = 10, P < 0.05) induced by GIP were significantly increased in isolated islets, suggesting hypersensitivity of the GIPR. Total GIPR mRNA expression was not increased in the islets of HFD mice, but the expression ratio of truncated GIPR to total GIPR was reduced by 32% compared with that of control mice (n = 6, P < 0.05). These results indicate that a relative reduction of truncated GIPR expression may be involved in hypersensitivity of GIPR and hyperinsulinemia in diet-induced obese mice.     

Generation of insulin-secreting cells from pancreatic acinar cells of animal models of type 1 diabetes

We recently found that pancreatic acinar cells isolated from normal adult mouse can transdifferentiate into insulin-secreting cells in vitro. Using two different animal models of type 1 diabetes, we show here that insulin-secreting cells can also be generated from pancreatic acinar cells of rodents in the diabetic state with absolute insulin deficiency. When pancreatic acinar cells of streptozotocin-treated mice were cultured in suspension in the presence of epidermal growth factor and nicotinamide under low-serum condition, expressions of insulin genes gradually increased. In addition, expressions of other pancreatic hormones, including glucagon, somatostatin, and pancreatic polypeptide, were also induced. Analysis by the Cre/loxP-based direct cell lineage tracing system revealed that these newly made cells originated from amylase-expressing pancreatic acinar cells. Insulin secretion from the newly made cells was significantly stimulated by high glucose and other secretagogues. In addition, insulin-secreting cells were generated from pancreatic acinar cells of Komeda diabetes-prone rats, another animal model of type 1 diabetes. The present study demonstrates that insulin-secreting cells can be generated by transdifferentiation from pancreatic acinar cells of rodents in the diabetic state and further suggests that pancreatic acinar cells represent a potential source of autologous transplantable insulin-secreting cells for treatment of type 1 diabetes.     

The clinical usefulness of liquid human growth hormone (hGH) (Norditropin SimpleXx in the treatment of GH deficiency

Human growth hormone (hGH) is an essential therapeutic drug for the treatment of GH deficiency. The development of recombinant GH using a pen injection system has enabled easy and safe treatment of GH-deficient patients; however, the process of dissolving hGH in the powder form is complicated and dangerous. In this study, we investigated the usefulness of a newly developed liquid form of hGH (Norditropin((R)) SimpleXx(TM)) in the treatment of 51 patients with GH deficiency. Fifteen previously untreated patients with GH deficiency were treated with liquid hGH (group A), and 36 patients who had previously used hGH in the powder form were changed to the liquid form (group B). Both groups were treated with liquid hGH 0.5 IU/kg per week for 6 months. The growth rate of patients in group A increased from 4.0 +/- 2.4 cm/year to 9.2 +/- 2.9 cm/year. The patients in group B continued to grow at the same rate as before using the liquid hGH therapy. Questionnaires to the patients in group B demonstrated that 85% preferred the convenience of using the new liquid form of hGH. Our results indicate that liquid hGH has similar efficacy to that of powder hGH, but its improved convenience may have a beneficial effect on patient compliance.     

Plastic changes of leaf mass per area and leaf nitrogen content in response to canopy openings in saplings of eight deciduous broad-leaved tree species

Leaf nitrogen content per area (N_area) is a good indicator of assimilative capacity of leaves of deciduous broad-leaved trees. This study examined the degrees of increase in N_area in response to canopy openings as leaf mass per area (LMA) and leaf nitrogen content per mass (N_mass) in saplings of eight deciduous broad-leaved tree species in Hokkaido, northern Japan. Five of the species were well-branched species with a large number of small leaves (lateral-growth type), and the other three species were less-branched species with a small number of large leaves (vertical-growth type). The degrees of increase in N_area were compared between the two crown types. In closed-canopy conditions, leaves of the vertical-growth species tended to have a lower LMA and higher N_mass than those of the lateral-growth species, which resulted in similar N_area for both. LMA increased in canopy openings in the eight species, and the degrees of increase were not largely different between the lateral- and vertical-growth species. On the contrary, N_mass was unchanged in canopy openings in the eight species. As a result, N_area of each species increased in canopy openings in proportion to the increase in LMA, and the degrees of increase in N_area were similar in the lateral- and vertical-growth species. Therefore, this study showed that the degrees of increase in N_area were not correlated with the crown architecture (i.e., the lateral- and vertical-growth types).