Insulinoma induces a hyperinsulinemia-mediated decrease of GLUT2 and GLP1 receptor in normal pancreatic β-cells

There have been several clinical reports of transient postoperative hyperglycemia in patients with insulinoma, but the effect of insulinoma on normal β-cells has not been investigated. We examined the glucose transporter 2 (GLUT2) and glucagon-like peptide 1 receptor (GLP1R) expression in normal pancreatic β-cells of five patients with insulinoma and five patients with normal glucose tolerance (NGT) as controls. The positive rate of GLUT2-or GLP1R-positive islets in the nontumor area was calculated by the ratio with the analyzed islets. For functional in vitro analyses, q-PCR and Western blotting were performed after insulin loading on MIN6 cells. The expression rates of both GLUT2 and GLP1R were significantly lower in nontumor area islets of insulinoma patients than in patients with NGT (GLUT2: 31.6 ± 15.3% vs 95.9 ± 6.7%, p < 0.01, GLP1R: 66.8 ± 15.0% vs 96.7 ± 5.0%, p < 0.01). Exposure of MIN6 cells to high concentrations of insulin resulted in a significant decrease in GLUT2 protein for 12 h and GLP1R protein for 24 h (GLUT2; 1.00 ± 0.079 vs 0.81 ± 0.04. p = 0.02, GLP1R; 1.00 ± 0.10 vs 0.50 ± 0.24, p = 0.03) but not in those mRNAs. Our findings show that insulinoma is associated with the downregulation of GLUT2 and GLP1R expression in nontumor area islets. These phenomena may be caused by high levels of insulin.

Influence of morphology and polymorphic transformation of fat crystals on the freeze-thaw stability of mayonnaise-type oil-in-water emulsions

This study examined the destabilization of an oil-in-water (O/W) emulsion by freeze-thawing with a focus on the influence of the morphology and polymorph of fat crystals. For a model of food emulsion, this study used a mayonnaise-type O/W emulsion containing 70wt% canola oil (canola emulsion) or soybean oil (soybean emulsion) stored at -15, -20, and -30°C. The freeze-thaw stabilities of the emulsions were evaluated by measuring the upper oil layer after freeze-thawing. The soybean emulsion kept at -20°C had the highest stability; the other emulsions were destabilized during 6h of storage. Crystallization in the emulsions was determined using differential scanning calorimetry (DSC), time variation of temperature, X-ray diffraction measurement, and polarized light microscopy. DSC thermograms indicated that crystallization in emulsions occurred first in the high-melting fraction of oil, followed by water and, last, in the low-melting fraction of oil during cooling to -40°C. In the canola emulsion, the amount of fat crystals derived from the low-melting fraction of oil increased during storage at all temperatures, resulting in partial coalescence. The soybean emulsion was expected to be destabilized by polymorphic transformation (sub-α to β' and β) of fat crystals derived from the high-melting fraction during storage at -15 and -20°C. However, the soybean emulsion did not exhibit polymorphic transformation stored at -30°C, and the amount of fat crystals did not increase during freezing; thus, it was destabilized via a different mechanism.

Precise frequency-difference measurement between the 1.66-mum transitions of methane

We determined 66 frequency differences (FD's) between rovibrational lines of methane at the 1.66-mum region. Following the technique developed by Nakagawa et al.[Opt.Lett.20, 410 (1995)], we measured the FD's as the optical beat frequency between two external-cavity diode lasers locked at 1-MHz-wide saturated absorption dips of the methane lines. Even though the methane lines often overlap in Doppler-limited resolution, the spectrometer that we use resolves them and determines their FD's with better than 40-kHz precision. This fact demonstrates that the methane lines are promising candidates for frequency reference and that this technique has great potential for high-resolution molecular spectroscopy.

Permanent Dipole Moments of Methane-Type Molecules: Calculation of the DeltaJ = 0 Matrix Elements in the l = 1 Vibrational State

We examined permanent dipole moments (PDMs) of methane-type molecules induced by molecular internal motions which are expanded in terms of the vibrational coordinate operator q , total angular momentum operator J , and vibrational angular momentum operator l . The qq -, JJ -, Jl -, and ll -type quadratic terms of these operators contribute to the production of PDMs. The DeltaJ = 0 matrix elements of the four PDMs are calculated for the first excited state of the triply degenerate vibrational mode; a portion are numerically given in a table for the J </= 6 levels. We have also compared them with the PDM represented by the rotational angular momentum operator R = J - l and discussed an application of the present calculations to the v 3 = 2 state of methane.

Impairment of pupillary responses and optokinetic nystagmus in the mGluR6-deficient mouse

Retinal bipolar cells receive glutamatergic transmission from photoreceptors and mediate a key process in segregating visual signals into ON-center and OFF-center pathways. The segregation of ON responses involves a G protein-coupled metabotropic glutamate receptor (mGluR). The mGluR6 subtype is expressed restrictedly at the postsynaptic site of retinal ON-bipolar cells. Ablation of mGluR6 in the ON-bipolar cells by gene targeting results in a loss of ON responses but unchanged OFF responses in visual transmission. Thus, mGluR6 is essential for inducing ON responses. The aims of this study are analyses of visual responsiveness and possible visual dysfunction in mGluR6-deficient mice. We report here that mGluR6-deficient mice have unaltered locomotor activity in a daily light-dark cycle and exhibit light-stimulated induction of Fos immunoreactivity in the suprachiasmatic nucleus. These findings indicate that mGluR6-deficient mice are capable or responding to light stimulation. The mGluR6 deficiency, however, markedly reduces the sensitivity of pupillary responses to light stimulus and severely impairs the ability to drive optokinetic nystagmus in response to visual contrasts. This study thus demonstrates that mGluR6 contributes to discrimination of visual contrasts.

[Preliminary study of radiological image transmission with B-ISDN]

We evaluated the utility of image transmission using broad band ISDN (B-ISDN). The B-ISDN network links Tohoku University Hospital (TUH), interfaced with CDDI, and Tohoku University Department of Technology, interfaced with FDDI (including Tohoku University Computer Center interfaced with Ethernet), at 10km distance interfaced to a Unix workstation. Voluminous radiographic images like MRI 3-D images of the pelvic organs digitized at 5-20 megabytes were transmitted at mean data rates of 1.03Mbps (CDDI-Ethernet) and 30.1Mbps (FDDI-CDDI) with no image distortion. Initially the image data are transmitted to the Computer Center & Department of Technology, then processed and relayed to TUH. B-ISDN can provide fast, accurate image transmission.

Behavioral and electroencephalographic properties of duloxetine (LY248686), a reuptake inhibitor of norepinephrine and serotonin, in mice and rats

Duloxetine is a dual inhibitor of norepinephrine and serotonin reuptake. Duloxetine (3.13-50 mg/kg p.o.) significantly prevented tetrabenazine (1 and 50 mg/kg s.c.)-induced ptosis in mice and rats. Moreover, duloxetine (1.56-12.5 mg/kg p.o.) also inhibited reserpine (1 mg/kg s.c.)-induced hypothermia in mice. When duloxetine (12.5-100 mg/kg p.o.) and 5-hydroxytryptophan (80 and 100 mg/kg i.p.), a precursor of serotonin, were administered simultaneously to mice and rats, head movement behavior and tremor were observed. In addition, duloxetine (25-100 mg/kg p.o.) significantly attenuated immobility in forced swimming in mice, as equally effective as commonly used antidepressant drugs. Duloxetine (12.5-25 mg/kg p.o.) significantly decreased rapid eye movement sleep and slow-wave deep sleep and increased the awake period, as shown in the rat EEG. However, duloxetine (25-200 mg/kg p.o.) did not affect salivation and lacrimation induced by oxotremorine (1 mg/kg s.c.), a cholinergic agonist, whereas it (25-50 mg/kg) reduced the oxotremorine-induced tremor in part. These results indicated that duloxetine produced behavioral and electroencephalographic responses resulting from the inhibition of norepinephrine and serotonin reuptake in vivo, and that it had a weak anticholinergic action. Therefore, duloxetine may be clinically useful as an antidepressant.

[MR imaging findings of nonketotic hyperglycinemia. 2 cases of neonatal onset]

We presented MR (magnetic resonance) images findings of the brain in nonketotic hyperglycinemia (NKH) from 2 patients of neonatal onset. MR findings in our cases of NKH are compatible with the pathological alterations described in the literature; MR images revealed delayed myelination of the cerebral white matter and hypoplasia of the corps callosum. The latter finding particularly seemed to be relatively characteristic to NKH. MR examination is the imaging modality of choice for this disease because it can demonstrate the degree of myelination, and development of the corpus callosum particularly on sagittal section.

Pharmacological studies on a new dihydrothienopyridine calcium antagonist, S-312-d. 5th communication: anticonvulsant effects in mice

S-312, S-312-d, but not S-312-l, L-type calcium channel antagonists, showed anticonvulsant effects on the audiogenic tonic convulsions in DBA/2 mice; and their ED50 values were 18.4 (12.8-27.1) mg/kg, p.o. and 15.0 (10.2-23.7) mg/kg, p.o., respectively, while that of flunarizine was 34.0 (26.0-44.8) mg/kg, p.o. Although moderate anticonvulsant effects of S-312-d in higher doses were observed against the clonic convulsions induced by pentylenetetrazole (85 mg/kg, s.c.) or bemegride (40 mg/kg, s.c.), no effects were observed in convulsions induced by N-methyl-D-aspartate, picrotoxin, or electroshock in Slc:ddY mice. S-312-d may be useful in the therapy of certain types of human epilepsy.

Ischemia-induced irreversible deficit of memory function in gerbils

Ischemia for 5 min temporarily increased locomotor activity in gerbils after 1 and 3 days. Temporary increases were also noted within 7 and 5 days after 20-min ischemia and repeated ischemia (three 2-min ischemia at 1-h intervals), respectively. In a passive avoidance task, gerbils were trained 2 or 14 days before the occlusion and then tested 1 day after it. Shortened step-through latency was observed in the retention test 3 days after 5-min ischemia, but not after 15 days (reversible deficit). In contrast, following 20-min ischemia, the step-through latency was significantly lower after 3 days and also after 15 days (irreversible deficit). Working memory was also tested with gerbils trained for an 8-arm radial maze task. A significantly higher working error was observed 1 day after 5-min ischemia but not after 5 days (reversible deficit). However, ischemia for 20-min and repeated ischemia led to markedly increase working error 1 day after the occlusion, with significant increases even after 14 and 28 days (irreversible deficit). In addition, while 5-min ischemia occurred the neuronal death in the hippocampal CA1 subfield, 20-min ischemia produced it not only in the CA1 subfield but also in the CA2-4 subfield and dorsal striatum. These results indicated that 5-min ischemia led to a reversible memory deficit, while 20-min and repeated ischemia produced an irreversible deficit.

[Effects of a new minor tranquilizer, 10-chloro-3-methyl-1 1b-(2-chlorophenyl)-2,3,5,6,7,11b-hexahydrobenzo [6,7]-1,4-diazepino [5,4-b]-oxazol-6-one (CS-386), on the after-discharge and behavior induced by electrical stimulation of the amygdala in freely-moving cats (author's transl)]

Effects of a new minor tranquilizer, CS-386, on the after-discharge(AD) and behavior induced by amygdaloid electrical stimulation in freely-moving cats were compared with those of cloxazolam, oxazolam, diazepam, chlordiazepoxide, phenobarbital and chlorphromazine. Effects on change of the AD threshold and duration and on facial twitching, salivation and tonic-clonic convulsion were investigated. CS-386, cloxazolam and oxazolam inhibited amygdaloid AD. CS-386 had the most potent inhibitory effect. These drugs depressed all behavior described above. Diazepam had no effects on the AD threshold, but decreased the AD duration and inhibited the behavior. Chlordiazepoxide had no apparent effects on amygdaloid AD and on facial twitching. Salivation was inhibited with high doses of administration. Phenobarbital shortened the AD duration and at a high dose elevated the AD threshold. This drug also inhibited salivation, but inhibitory effects on other behavior required doses as high as 90 mg/kg. These results suggest that CS-386, cloxazolam and oxazolam are compounds belonging to a classification different from that of chlorpromazine. CS-386 in particular, is a more potent drug chlordiazepoxide, diazepam and phenobarbital and acts on the amygdala itself.