Protein Kinase C (Pkc)-δ Mediates Arginine-Induced Glucagon Secretion in Pancreatic α-Cells

The pathophysiology of type 2 diabetes involves insulin and glucagon. Protein kinase C (Pkc)-δ, a serine-threonine kinase, is ubiquitously expressed and involved in regulating cell death and proliferation. However, the role of Pkcδ in regulating glucagon secretion in pancreatic α-cells remains unclear. Therefore, this study aimed to elucidate the physiological role of Pkcδ in glucagon secretion from pancreatic α-cells. Glucagon secretions were investigated in Pkcδ-knockdown InR1G9 cells and pancreatic α-cell-specific Pkcδ-knockout (αPkcδKO) mice. Knockdown of Pkcδ in the glucagon-secreting cell line InR1G9 cells reduced glucagon secretion. The basic amino acid arginine enhances glucagon secretion via voltage-dependent calcium channels (VDCC). Furthermore, we showed that arginine increased Pkcδ phosphorylation at Thr505, which is critical for Pkcδ activation. Interestingly, the knockdown of Pkcδ in InR1G9 cells reduced arginine-induced glucagon secretion. Moreover, arginine-induced glucagon secretions were decreased in αPkcδKO mice and islets from αPkcδKO mice. Pkcδ is essential for arginine-induced glucagon secretion in pancreatic α-cells. Therefore, this study may contribute to the elucidation of the molecular mechanism of amino acid-induced glucagon secretion and the development of novel antidiabetic drugs targeting Pkcδ and glucagon.

Combined damage to the right hemispheric hand area in the primary motor and sensory area plays a critical role in motor hemineglect

Direct evidence of the anatomical localization of brain function is provided by functional neurological changes during awake surgery combined with data from preoperative functional magnetic resonance imaging and diffusion tensor imaging studies. The goal of the present study was to analyze the etiology and mechanism of motor hemineglect using these techniques. Of 29 patients with brain tumors within and near the primary motor area (M1) in whom awake surgery was employed from April 2004 through March 2007, 2 patients evinced motor hemineglect of the left hand during awake surgery. The brain tumors in these 2 cases alone were located just beside the hand area of M1 and the primary sensory area (S1) in the right hemisphere. In case 1, the U fibers that connected the areas activated by hand clenching in M1 with S1 were compressed by the brain tumor. These results suggest that the combination of damage to the right hemispheric hand area in M1 and S1 plays a critical role in the development of motor hemineglect.

Damage to the right superior longitudinal fasciculus in the inferior parietal lobe plays a role in spatial neglect

Functional neurological changes after surgery combined with data from diffusion tensor imaging (DTI) studies can provide direct evidence of anatomical localization of brain function. The goal of the present study was to characterize mechanisms of spatial neglect using these techniques by analyzing two patients with development or worsening of left neglect after surgery at our hospital in 2008. In both cases, the surgical approach was via the right inferior parietal lobes, and damage to the superior longitudinal fasciculus (SLF) was demonstrated after surgery by DTI tractography. By contrast, neither the inferior longitudinal fasciculus (ILF) nor the inferior fronto-occipital fasciculus (IFOF) was damaged. These results suggest that damage to the right SLF in the inferior parietal lobe plays a critical role in the development of spatial neglect.

Assessment of the corona radiata sensory tract using awake surgery and tractography

Anatomical localization of brain function can be achieved by functional changes during awake surgery combined with tractography constructed by diffusion tensor imaging studies. We aimed to use these techniques to characterize the sensory tract in the corona radiata in patients with closely associated brain tumors. Of nine patients who had brain tumors in the primary sensory area (S1) and who underwent awake surgery between October 2004 and July 2007, two patients showed deterioration in deep sensation during and after awake surgery. Both of these patients also developed involuntary movements (for patient 1 this was myoclonus of the left hand, while patient 2 experienced unintentional lifting of the arm). In these two patients, tumors were located just beside the sensory tract in the corona radiata of the right hemisphere. In patient 2, Wallerian degeneration of the sensory tract and concomitant deterioration of superficial and deep sensation were observed at 6 months after awake surgery. These results suggest that damage to a closely associated sensory tract in the corona radiata is critical to the development of sensory deficits and involuntary movements. For patients who undergo surgical resection of S1 brain tumors, pre-operative tractography to detect the sensory tract in the corona radiata may allow protection of the sensory tract during awake surgery, thereby preventing post-operative sensory deficits.

A novel amino acid substitution at the receptor-binding site on the hemagglutinin of H3N2 influenza A viruses isolated from 6 cases with acute encephalopathy during the 1997-1998 season in Tokyo

We analyzed the hemagglutinin (HA) genes of influenza A viruses consisting of 6 strains isolated from cerebrospinal fluids of patients with encephalopathy and 3 isolates from throat washes of patients without central nervous system symptoms during the 1997-1998 season in Tokyo. Aligned 9 amino acid sequences showed 7 common substitutions compared with A/Wuhan/359/95 (vaccine strain used in the season in Japan), which were allocated to three different antigenic sites on the H3 HA molecule. It is noted that a novel substitution at the receptor-binding site (Tyr-137 to Phe) was found exclusively in the isolates from the patients with encephalopathy.

[Increased IL-2 and sIL-2R in sera of infants with HTLV-I infection from mother]

In our laboratory, children born to women are known to be infected with Human T-cell Leukemia Virus type-1 (HTLV-I) have been followed using, detect of gene by PCR and antibody by Western Blot Assay (WB) and Immunofluorescence Assay (IFA) test from 1990 through 1996. Four children out of 123 delivery cases have been confirmed to be infected with HTLV-I. We analyzed the correlation between the concentration of cytokines (IL-2, sIL-2R, IFN-gamma) and HTLV-I infection. IL-2 and sIL-2R in sera increased after HTLV-I infection. There was no correlation between the concentration of IFN-gamma and HTLV-I infection. These result suggested that detection of IL-2 and sIL-2R might be the marker of HTLV-I infection.

Transgenic cucumber plants harboring a rice chitinase gene exhibit enhanced resistance to gray mold (Botrytis cinerea)

A rice chitinase cDNA (RCC2) driven by the CaMV 35S promoter was introduced into cucumber (Cucumis sativus L.) through Agrobacterium mediation. More than 200 putative transgenic shoots were regenerated and grown on MS medium supplemented with 100 mg/l kanamycin. Sixty elongated shoots were examined for the presence of the integrated RCC2 gene and subsequently confirmed to have it. Of these, 20 were tested for resistance against gray mold (Botrytis cinerea) by infection with the conidia: 15 strains out of the 20 independent shoots exhibited a higher resistance than the control (non-transgenic plants). Three transgenic cucumber strains (designated CR29, CR32 and CR33) showed the highest resistance against B. cinerea: the spread of disease was inhibited completely in these strains. Chitinase gene expression in highly resistant transgenic strains (CR32 and CR33) was compared to that of a susceptible transgenic strain (CR20) and a control. Different responses for disease resistance were observed among the highly resistant strains. CR33 inhibited appressoria formation and penetration of hyphae. Although CR32 permitted penetration of hyphae, invasion of the infection hyphae was restricted. Furthermore, progenies of CR32 showed a segregation ratio of 3:1 (resistant:susceptible). As the disease resistance against gray mold was confirmed to be inheritable, these highly resistant transgenic cucumber strains would serve as good breeding materials for disease resistance.

Combination of thidiazuron and basal media with low salt concentrations increases the frequency of shoot organogenesis in soybeans [Glycine max (L.) Merr.]

A successful, efficient system for multiple soybean shoot induction of soybean [Glycine max (L.) Merr.] is reported. Multiple shoots were induced from cotyledonary nodes and hypocotyl segments cultured on media supplemented with 2 mg/l thidiazuron (TDZ) or 1.15 mg/l benzyladenine (BA). It was found that TDZ induced adventitious shoots more efficiently than BA and that hypocotyl segments promoted more adventitious shoots than cotyledonary nodes. The optimal TDZ concentrations for shoot organogenesis from hypocotyl segments were between 1 and 2 mg/l. Basal media also influenced the efficiency of shoot organogenesis. The frequency of adventitious shoot formation tended to increase when the salt concentration in the basal media supplemented with 2 mg/l TDZ was reduced. Two media (1/2B5 and 1/2L2) stimulated shoot organogenesis efficiently from hypocotyl segments. This method can thus be advantageously applied in the production of transgenic soybean plants.

Differential display identifies developmentally regulated genes during somatic embryogenesis in eggplant (Solanum melongena L.)

Changes in gene expression patterns during early somatic embryogenesis of eggplant (Solanum melongena L.) were characterized by means of differential display. Eight products of polymerase chain reaction (PCR) derived from newly expressed mRNAs after four days of culture were identified and cloned. One clone, pTM002, was found to contain a 416 bp insert and identical to the proximal arbitrary primer at both ends. Based on the terminal sequences, reverse-transcription PCR (RT-PCR) was carried out to monitor the expression level of pTM002. The results indicated that the message of pTM002 was increased to correlate with the intensities obtained in the differential display. The significance of this method in investigation of differentially expressed genes is also discussed.

[Studies on maternal transmission of HIV-1]

To investigate HIV-1 transmission from mother to child, samples taken from 3 HIV-1 sero-positive pregnant mothers, 3 children born by caesareans from their mothers and therapeutic abortion from 2 HIV-1 sero-positive mothers were tested for HIV-1 antibody by westernblot, p24 antigen by antigen captured ELISA, proviral DNA by Nested-PCR and isolation of HIV-1 virus from peripheral blood, cord blood, amniotic fluid and placenta. HIV-1 proviral DNA was detected in the peripheral blood of all mothers, but p24 antigen and virus isolation were not detected. None of the HIV-1 markers, except for antibody, was detected in the samples from their children and placenta. These facts strongly suggest that there was no HIV-1 transmission from mother to child.

Regulation of organogenesis and somatic embryogenesis by auxin in melon, Cucumis melo L

Various tissues of seeds and seedlings of melon were cultured in vitro to study the effects of auxin concentration on organogenesis and embryogenesis. Adventitious shoots and somatic embryos were formed from explants of cotyledons of mature seeds, hypocotyls of seedlings, and leaves and petioles of young plantlets. Expanded cotyledons of seedlings formed only adventitious shoots. All tissues responded similarly to the 2,4-D concentration in the media, that is, adventitious shoots were formed at low concentration, callus proliferated without differentiation at intermediate concentration and somatic embryos were induced at high concentration. Cotyledons of mature seeds formed both adventitious shoots and somatic embryos more efficiently than any other tissues cultured.Effects of three auxins, 2,4-D, NAA and IAA, on organogenesis and embryogenesis were compared using cotyledons of mature seeds. Adventitious shoots were formed at low level of auxins (0 to 0.01 mg/l 2,4-D; 0 to 0.1 mg/l NAA; 0 to 1.0 mg/l IAA), and embryos were formed at high level of auxins (1.0 to 2.0 mg/l 2,4-D; 3.0 to 10.0 mg/l NAA; 20.0 to 100.0 mg/l IAA). IAA gave more efficient shoot formation and embryogenesis than the other auxins.