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Author

Kunihiko Tanaka

Other affiliations: Gifu University
Bio: Kunihiko Tanaka is an academic researcher from Gifu University of Medical Science. The author has contributed to research in topics: Vestibular system & Galvanic vestibular stimulation. The author has an hindex of 18, co-authored 95 publications receiving 938 citations. Previous affiliations of Kunihiko Tanaka include Gifu University.


Papers
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Journal ArticleDOI
TL;DR: During spaceflight or exposure to microgravity, the load on the musculoskeletal system and hydrostatic pressure difference is diminished, and skeletal muscle, particularly in the lower limbs, is atrophied, and bone minerals are lost via urinary excretion.
Abstract: Humans are generally in standing or sitting positions on Earth during the day. The musculoskeletal system supports these positions and also allows motion. Gravity acting in the longitudinal direction of the body generates a hydrostatic pressure difference and induces footward fluid shift. The vestibular system senses the gravity of the body and reflexively controls the organs. During spaceflight or exposure to microgravity, the load on the musculoskeletal system and hydrostatic pressure difference is diminished. Thus, the skeletal muscle, particularly in the lower limbs, is atrophied, and bone minerals are lost via urinary excretion. In addition, the heart is atrophied, and the plasma volume is decreased, which may induce orthostatic intolerance. Vestibular-related control also declines; in particular, the otolith organs are more susceptible to exposure to microgravity than the semicircular canals. Using an advanced resistive exercise device with administration of bisphosphonate is an effective countermeasure against bone deconditioning. However, atrophy of skeletal muscle and the heart has not been completely prevented. Further ingenuity is needed in designing countermeasures for muscular, cardiovascular, and vestibular dysfunctions.

79 citations

Journal ArticleDOI
TL;DR: Ground-based results support spaceflight evaluation of postexercise orthostatic stress as a time-efficient countermeasure against postflight Orthostatic intolerance.
Abstract: Orthostatic intolerance follows actual weightlessness and weightlessness simulated by bed rest. Orthostasis immediately after acute exercise imposes greater cardiovascular stress than orthostasis without prior exercise. We hypothesized that 5 min/day of simulated orthostasis [supine lower body negative pressure (LBNP)] immediately following LBNP exercise maintains orthostatic tolerance during bed rest. Identical twins (14 women, 16 men) underwent 30 days of 6° head-down tilt bed rest. One of each pair was randomly selected as a control, and their sibling performed 40 min/day of treadmill exercise while supine in 53 mmHg (SD 4) [7.05 kPa (SD 0.50)] LBNP. LBNP continued for 5 min after exercise stopped. Head-up tilt at 60° plus graded LBNP assessed orthostatic tolerance before and after bed rest. Hemodynamic measurements accompanied these tests. Bed rest decreased orthostatic tolerance time to a greater extent in control [34% (SD 10)] than in countermeasure subjects [13% (SD 20); P < 0.004]. Controls exhibited cardiac stroke volume reduction and relative cardioacceleration typically seen after bed rest, yet no such changes occurred in the countermeasure group. These findings demonstrate that 40 min/day of supine LBNP treadmill exercise followed immediately by 5 min of resting LBNP attenuates, but does not fully prevent, the orthostatic intolerance associated with 30 days of bed rest. We speculate that longer postexercise LBNP may improve results. Together with our earlier related studies, these ground-based results support spaceflight evaluation of postexercise orthostatic stress as a time-efficient countermeasure against postflight orthostatic intolerance.

55 citations

Journal ArticleDOI
TL;DR: Results indicate that Mn(2+) contrasted MRI is a useful technique for investigating the autonomic center in the hypothalamus, and are consistent with the Fos expression results.

42 citations

Journal ArticleDOI
TL;DR: In this article, the authors describe the Reaktion der Ester (III) with Bortribromid and Aminen (II) bzw. anderen A1?′ koholen (IV) entstehen die Amide (I) bzzw.

40 citations

Journal ArticleDOI
TL;DR: GVS modified the AP responses in young subjects during HUT but not during LBNP, suggesting that the vestibular system plays an important role in initial AP control during posture transition in young Subjects, however, this function might be impaired in aged subjects.
Abstract: We recently demonstrated that galvanic vestibular stimulation (GVS) obscured the vestibulo-cardiovascular reflex in rats during gravitational change. Here, we used GVS to examine the role of the vestibular-mediated arterial pressure (AP) control during a 60° head-up tilt (HUT) in young and aged subjects (19–24 years old, 12 males and 3 females for young subjects, 63–91 years old, 5 males and 5 females for aged subjects). In young subjects, the AP did not change during posture transition from the supine position to HUT when GVS was not applied. When GVS was applied, AP immediately and significantly decreased by 17 ± 2 mmHg upon HUT. When they were exposed to lower-body negative pressure (LBNP) in the supine position, the degree of footward fluid shift induced was the same as that induced by HUT. LBNP elicited only a footward fluid shift without alteration of vestibular input, while HUT elicited both. LBNP decreased the AP significantly, and the decrease was similar to that observed in the HUT with GVS. Thus, GVS modified the AP responses in young subjects during HUT but not during LBNP. In contrast, in aged subjects, the AP decreased during HUT regardless of whether GVS was applied. The vestibular system plays an important role in initial AP control during posture transition in young subjects. However, this function might be impaired in aged subjects.

38 citations


Cited by
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01 Jan 1993
TL;DR: This work states that for many years, bone was defined anatomically and examined largely in a descriptive manner by ultrastructural analysis and by biochemical and histochemical methods, but now, complemented by an increased knowledge of molecular mechanisms that are associated with and regulate expression of genes encoding phenotypic compone...
Abstract: I. Introduction A FUNCTIONAL relationship between cell growth and the initiation and progression of events associated with differentiation has been a fundamental question challenging developmental biologists for more than a century. In the case of bone, as observed with other cells and tissue, the relationship of growth and differentiation must be maintained and stringently regulated, both during development and throughout the life of the organism, to support tissue remodeling. For many years, bone was defined anatomically and examined largely in a descriptive manner by ultrastructural analysis and by biochemical and histochemical methods. These studies provided the basis for our understanding of bone tissue organization and orchestration of the progressive recruitment, proliferation, and differentiation of the various cellular components of bone tissue. Now, complemented by an increased knowledge of molecular mechanisms that are associated with and regulate expression of genes encoding phenotypic compone...

982 citations

Journal Article
TL;DR: Inadequate training or inattention to detail during this aspect of a study may result in unintentional adverse effects on experimental animals and confounded results.
Abstract: Administration of substances to laboratory animals requires careful consideration and planning to optimize delivery of the agent to the animal while minimizing potential adverse experiences from the procedure. For all species, many different routes are available for administration of substances. The research team and IACUC members should be aware of reasons for selecting specific routes and of training and competency necessary for personnel to use these routes effectively. Once a route is selected, issues such as volume of administration, site of delivery, pH of the substance, and other factors must be considered to refine the technique. Inadequate training or inattention to detail during this aspect of a study may result in unintentional adverse effects on experimental animals and confounded results.

701 citations

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TL;DR: Recent advances in the understanding of the molecular, cellular and network mechanisms that mediate the central control of osmotic homeostasis in mammals are reviewed.
Abstract: Systemic osmoregulation is a vital process whereby changes in plasma osmolality, detected by osmoreceptors, modulate ingestive behaviour, sympathetic outflow and renal function to stabilize the tonicity and volume of the extracellular fluid. Furthermore, changes in the central processing of osmosensory signals are likely to affect the hydro-mineral balance and other related aspects of homeostasis, including thermoregulation and cardiovascular balance. Surprisingly little is known about how the brain orchestrates these responses. Here, recent advances in our understanding of the molecular, cellular and network mechanisms that mediate the central control of osmotic homeostasis in mammals are reviewed.

612 citations

Journal ArticleDOI
TL;DR: In the present work the different approaches to MEMRI are reviewed from a practical standpoint and emphasis is given to the experimental methodology of how to achieve significant, yet safe, amounts of Mn2+ to the target areas of interest.
Abstract: Manganese-enhanced MRI (MEMRI) is being increasingly used for MRI in animals due to the unique T1 contrast that is sensitive to a number of biological processes. Three specific uses of MEMRI have been demonstrated: to visualize activity in the brain and the heart; to trace neuronal specific connections in the brain; and to enhance the brain cytoarchitecture after a systemic dose. Based on an ever-growing number of applications, MEMRI is proving useful as a new molecular imaging method to visualize functional neural circuits and anatomy as well as function in the brain in vivo. Paramount to the successful application of MEMRI is the ability to deliver Mn2+ to the site of interest at an appropriate dose and in a time-efficient manner. A major drawback to the use of Mn2+ as a contrast agent is its cellular toxicity. Therefore, it is critical to use as low a dose as possible. In the present work the different approaches to MEMRI are reviewed from a practical standpoint. Emphasis is given to the experimental methodology of how to achieve significant, yet safe, amounts of Mn2+ to the target areas of interest.

479 citations

Journal ArticleDOI
TL;DR: In this review, attempts have been made to disclose various tactical approaches to synthesize pyrrole and pyr role containing analogs along with their therapeutic applications which have been reported during last decade.
Abstract: Pyrrole is widely known as a biologically active scaffold which possesses a diverse nature of activities. The combination of different pharmacophores in a pyrrole ring system has led to the formation of more active compounds. Pyrrole containing analogs are considered as a potential source of biologically active compounds that contains a significant set of advantageous properties and can be found in many natural products. The marketed drugs containing a pyrrole ring system are known to have many biological properties such as antipsychotic, β-adrenergic antagonist, anxiolytic, anticancer (leukemia, lymphoma and myelofibrosis etc.), antibacterial, antifungal, antiprotozoal, antimalarial and many more. Due to the diversity of these analogs in the therapeutic response profile, many researchers have been working to explore this skeleton to its maximum potential against several diseases or disorders. In this review, attempts have been made to disclose various tactical approaches to synthesize pyrrole and pyrrole containing analogs. The structure–activity relationship studies have been discussed along with their therapeutic applications which have been reported during last decade. Some molecules as the main components of the market and clinical trials have also been discussed.

429 citations