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301.
Hyperinsulinism-hyperammonemia syndrome caused by mutant glutamate dehydrogenase accompanied by novel enzyme kinetics 总被引:2,自引:0,他引:2
T. Yorifuji Junko Muroi Ayumi Uematsu Hidefumi Hiramatsu Toru Momoi 《Human genetics》1999,104(6):476-479
Hyperinsulinism-hyperammonemia syndrome (HHS) is a recently identified genetic disorder characterized by hyperinsulinemic
hypoglycemia with concomitant hyperammonemia. In patients with HHS, activating mutations in the glutamate dehydrogenase (GDH)
gene have been identified. GDH is a key enzyme linking glutamate metabolism with the Krebs cycle and catalyzes the conversion
of glutamate to α-ketoglutarate. The activity of GDH is controlled by allosteric inhibition by GTP and, so far, all the mutations
of HHS patients have been located within the GTP-binding site. Characteristically, GDH from these individuals have therefore
normal basal activity in conjunction with a loss of GTP inhibition. In this study, however, we have identified a novel variant
GDH in a patient with a more severe form of HHS. The mutation is located outside the GTP-binding site and the patient’s GDH
shows consistently higher activity, even in the absence of allosteric effectors. These results further support the hypothesis
that the activating mutation of GDH is the cause of HHS. The mechanism leading to the activation of GDH, however, is not always
related to the loss of GTP inhibition as was originally suggested.
Received: 4 January 1999 / Accepted: 11 March 1999 相似文献
302.
The morphofunctional development of Sertoli cells defines the testicular differentiation. These somatic cells are mostly of mesonephric origin and can be first recognized in 7 week-old embryos altogether with the formation of testicular cords. The latter organize as primordial germ cells surrounded by pre-Sertoli cells. Due to the great synthetic activity of pre-Sertoli cells the rough endoplasmic reticulum develops. The basal lamina of the cords becomes distinguishable at 7 to 8 weeks of development. Either prespermatogonia and pre-Sertoli cells actively proliferate but the latter greatly outnumber prespermatogonia. Many interdigitations and cytoplasmic processes are observed between neighboring pre-Sertoli cells. Due to the proliferative activity a sort of compartmentalization is established inside the cords in which pre-Sertoli cells tend to localize closer to the basal membrane embracing the prespermatogonia with long and thin cytoplasmic processes. One of the main features typical of differentiating pre-Sertoli cells is the irregular nucleus and the prominent nucleolus. When the embryo is 14 to 20 weeks-old the most significative change is the maximum development of the Leydig cells. Testicular cords do not show lumen at all, so they cannot be termed “tubules” 相似文献
303.
Shintaro Onishi Hidefumi Kitazawa Ichiro Tokimitsu 《Bioscience, biotechnology, and biochemistry》2018,82(9):1568-1575
Epidemiological studies suggest that green tea extracts (GTEs), including catechins such as epigallocatechin gallate and epicatechin gallate, have a beneficial effect on obesity, hyperglycemia, insulin resistance, endothelial dysfunction, and inflammation. Although several studies have shown that catechins directly modulate the cellular and molecular alterations in the liver tissue, the contributions of indirect mechanisms underlying these systemic effects of catechins remain unclear. In this study, we report that, in the C57BL/6J mouse liver, GTEs reduce high-fat diet-induced increases in the levels of hepatokines, liver-derived secretary proteins such as leukocyte cell-derived chemotaxin 2 and selenoprotein P production, which have been shown to induce systemic adverse effects, including several metabolic diseases. These findings suggest that the systemic effects of GTEs involve the regulation of hepatokine production as an indirect mechanism. 相似文献
304.
Hidefumi Maeda 《World journal of stem cells》2020,12(9):1023-1031
The periodontal ligament (PDL) is an essential fibrous tissue for tooth retention in the alveolar bone socket. PDL tissue further functions to cushion occlusal force, maintain alveolar bone height, allow orthodontic tooth movement, and connect tooth roots with bone. Severe periodontitis, deep caries, and trauma cause irreversible damage to this tissue, eventually leading to tooth loss through the destruction of tooth retention. Many patients suffer from these diseases worldwide, and its prevalence increases with age. To address this issue, regenerative medicine for damaged PDL tissue as well as the surrounding tissues has been extensively investigated regarding the potential and effectiveness of stem cells, scaffolds, and cytokines as well as their combined applications. In particular, PDL stem cells (PDLSCs) have been well studied. In this review, I discuss comprehensive studies on PDLSCs performed in vivo and contemporary reports focusing on the acquisition of large numbers of PDLSCs for therapeutic applications because of the very small number of PDLSCs available in vivo. 相似文献
305.
Tomomi Nakao Tsuyoshi Otsuka Zaw Lin Thein Hue Thi Le Hidefumi Waki 《Chronobiology international》2018,35(4):499-510
The daily rhythm of glucose metabolism is governed by the circadian clock, which consists of cell-autonomous clock machineries residing in nearly every tissue in the body. Disruption of these clock machineries either environmentally or genetically induces the dysregulation of glucose metabolism. Although the roles of clock machineries in the regulation of glucose metabolism have been uncovered in major metabolic tissues, such as the pancreas, liver, and skeletal muscle, it remains unknown whether clock function in non-major metabolic tissues also affects systemic glucose metabolism. Here, we tested the hypothesis that disruption of the clock machinery in the heart might also affect systemic glucose metabolism, because heart function is known to be associated with glucose tolerance. We examined glucose and insulin tolerance as well as heart phenotypes in mice with heart-specific deletion of Bmal1, a core clock gene. Bmal1 deletion in the heart not only decreased heart function but also led to systemic insulin resistance. Moreover, hyperglycemia was induced with age. Furthermore, heart-specific Bmal1-deficient mice exhibited decreased insulin-induced phosphorylation of Akt in the liver, thus indicating that Bmal1 deletion in the heart causes hepatic insulin resistance. Our findings revealed an unexpected effect of the function of clock machinery in a non-major metabolic tissue, the heart, on systemic glucose metabolism in mammals. 相似文献
306.
Hidefumi Yamakawa Toshiaki Ishibashi Takayuki Abe Toshifumi Hatta Kazuyuki Takai Hiroshi Takaku 《Nucleosides, nucleotides & nucleic acids》2013,32(7-9):1713-1716
Abstract We have designed a new type of antisense oligonucleotide, containing two hairpin loop structures with RNA/DNA base pairs (sense (RNA) and antisense (DNA)) in the double helical stem (nicked and circular dumbbell DNA/RNA chimeric oligonucleotides). The reaction of the nicked and circular dumbbell DNA/RNA chimeric oligonucleotides with RNase H gave the corresponding anti-DNA together with the sense RNA cleavage products. These oligonucleotides were more resistant to exonuclease attack. We also describe the anti-Fluv activities of nicked and circular dumbbell DNMA chimeric oligonucleotides. 相似文献
307.
Although there have been several studies on the structure of the ocellus photoreceptors in ascidian tadpole larvae using electron microscopy, the overall structure of these photoreceptor cells, especially the projection sites of the axons, has not been revealed completely. The number of photoreceptor cells is also controversial. Here, the whole structure of the ocellus photoreceptors in the larvae of the ascidian Ciona intestinalis was revealed by using an anti‐arrestin (anti–Ci‐Arr) antibody. The cell bodies of 30 photoreceptor cells covered the right side of the ocellus pigment cell and their outer segments extended through the pigment cell into the pigment cup. The axons of the photoreceptor cells were bundled together ventro‐posteriorly in a single tract extending towards the midline. The nerve terminals diverged antero‐posteriorly at the midline of the posterior sensory vesicle (SV). The Ci‐arr gene was expressed throughout the SV at the embryonic mid‐tailbud stage and it became restricted to the neighborhood of the ocellus pigment when ocellus pigmentation occurred. At the same time, the Ci‐Arr protein was first detected, suggesting that the photoreceptor cells began to differentiate. The development of photoreceptor cells after hatching was also investigated using the anti–Ci‐Arr antibody. Three hours after hatching, the photoreceptor terminals began to ramify and then expanded. Previous behavioral analysis showed that the larvae did not respond to the step‐down of light until 2 h after hatching and then the photoresponse became robust. Accordingly, our results suggest that growth of the photoreceptor terminal is critical for the larvae to become photoresponsive. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2005 相似文献