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Biomedical subjects

Masaki Yoshida

Publications and source records attributed to Masaki Yoshida.

At least 19 recordsLinked to original sources

An algorithm for detecting startle state based on physiological signals.

To construct safe workspaces or daily life environments, it is important to develop a technology for automatically recording dangerous environmental situations. Based on increased finger skin conductance and decreased instantaneous heart (pulse) rate, we developed an algorithm for detecting the startle state of humans when encountering dangerous situations. The parameter values in the algorithm were optimized by tuning them with experimental results obtained in a virtual reality system, in which dangerous scenarios were presented to 21 subjects. The detection sensitivity of the optimized algorithm was 100% during a static standing condition and also while cycling. The detection specificity attained 90% and 87% for the static and exercising conditions, respectively. The optimized algorithm was applied to a real world situation such as car driving, and relatively high sensitivity of 87% and specificity of 80% were obtained.

Adolescent↗

Molecular cloning of a murine glycerol-3-phosphate acyltransferase-like protein 1 (xGPAT1).

A novel murine glycerol-3-phosphate acyltransferase-like protein 1 (named xGPAT1) has been cloned. The mouse xGPAT1 gene is located on mouse Chromosome 2, spans >19 kb, and consists of at least 23 exons. The protein is 32% identical and 72% similar to mouse mitochondrial GPAT (mtGPAT) on the amino acid level. Sequencing analysis confirmed that xGPAT1 has a 2403-bp open reading frame (ORF) that encodes an 801-amino acid protein with an estimated molecular mass of 89.1 kDa. A hydropathy plot of the deduced xGPAT1 protein showed a high degree of similarity with that of the mtGPAT protein. Using 5'-rapid amplification of cDNA ends, two alternate, untranslated exon 1 (1a and b) isoforms were obtained, generating variants xGPAT1-v1 and xGPAT1-v2. xGPAT1-v1 is expressed in mouse heart, liver, spleen, kidney and murine inner medullary collecting duct 3 (mIMCD3) cells, while xGPAT1-v2 is expressed in mouse liver, spleen, kidney, white and brown adipose tissues and 3T3-L1 pre- and post-adipocytes. xGPAT1 was distributed in the membrane fraction and showed GPAT activity when epitope-tagged xGPAT1 was expressed in Chinese hamster ovary (CHO)-K1 cells.

Amino Acid Sequence↗

Silodosin, a new alpha1A-adrenoceptor-selective antagonist for treating benign prostatic hyperplasia: results of a phase III randomized, placebo-controlled, double-blind study in Japanese men.

OBJECTIVE: To verify the efficacy and safety of the new alpha1A-adrenoceptor-selective antagonist silodosin compared with tamsulosin and placebo in patients with lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: This randomized, double-blind, placebo-controlled study was conducted at 88 centres in Japan. Men aged > or = 50 years with an International Prostate Symptom Score (IPSS) of > or = 8, a quality-of-life (QoL) score of > or = 3, a maximum urinary flow rate (Qmax) of < 15 mL/s, a prostate volume of > or = 20 mL and a postvoid residual urine volume of < 100 mL were eligible for enrolment. Patients were randomized to receive silodosin 4 mg twice daily, tamsulosin 0.2 mg once daily, or placebo, for 12 weeks. The primary endpoint was the change in IPSS from baseline. Safety was assessed by adverse events, physical examination, vital signs and laboratory tests. RESULTS: In all, 457 patients were randomized (silodosin 176, tamsulosin 192 and placebo 89). The change in the total IPSS from baseline in the silodosin, tamsulosin and placebo groups was -8.3, -6.8 and -5.3, respectively. There was a significant decrease in the IPSS vs placebo in the silodosin group from 1 week. In the early-stage comparison, silodosin showed a significant decrease in IPSS vs tamsulosin at 2 weeks. The change in QoL from baseline was -1.7, -1.4 and -1.1 in the silodosin, tamsulosin and placebo groups, respectively; silodosin showed a significant improvement in the QoL score vs placebo. In the subgroup of patients with severe symptoms (IPSS > or = 20) silodosin also gave a significantly better improvement than placebo (-12.4 vs -8.7). The incidence rates of adverse events and drug-related adverse events were, respectively, 88.6%, 82.3% and 71.6% and 69.7%, 47.4% and 36.4%, respectively. The most common adverse event in the silodosin group was abnormal ejaculation, which occurred more often in the silodosin than in the tamsulosin group (22.3% vs 1.6%). However, only five men (2.9%) discontinued treatment for abnormal ejaculation. CONCLUSION: Silodosin was generally effective in the absence of obtrusive side-effects. This study suggests that silodosin is clinically useful for treating LUTS associated with BPH.

Adrenergic alpha-Antagonists↗

A haptophyte bearing siliceous scales: ultrastructure and phylogenetic position of Hyalolithus neolepis gen. et sp. nov. (Prymnesiophyceae, Haptophyta).

A haptophyte alga bearing hyaline but conspicuous scales was discovered in surface water samples of Shiribeshi Seamount, Japan. X-ray elemental analysis confirmed that silica was the major element in these scales. These scales were hat-shaped, ellipsoidal in top view, 4-6mum wide and 5-7mum long, perforated by several small pores, and were deposited on cells in several layers. Beneath the siliceous scale layers, organic scales were present, which are typical of haptophytes. The cells were non-motile despite having two short flagella hidden in the scale case. The haptonema, extended over the scale case, and one and a half times the cell length. The intracellular features were typical of haptophytes, including the peripheral endoplasmic reticulum (PER), Golgi cisternae with peculiar dilations, and the flagellar apparatus. The siliceous scales were produced in vesicles in the posterior region of the cell. Motile cells lacking silica scales were observed occasionally when cultures were maintained at lower temperatures and under oligotrophic conditions. This alga was described as Hyalolithus neolepis gen. et sp. nov. Phylogenetic analysis using the SSU rDNA and rbcL gene sequences indicated that Hyalolithus is a member of the Prymnesiales and falls in a clade including Prymnesium, Platychrysis, and Chrysochromulina polylepis. Based on these results, the evolutionary implications of the presence of silicified scales in haptophytes is discussed.

Animals↗

ATP2C1 is specifically localized in the basal layer of normal epidermis and its depletion triggers keratinocyte differentiation.

BACKGROUND: ATP2C1 is a calcium/manganese-ATPase localized in the Golgi apparatus and known as responsible gene for Hailey-Hailey disease. But its localization and roles in the epidermis are not fully elucidated. OBJECTIVE: To explore the localization and biological role of ATP2C1 in normal epidermis in terms of differentiation states. METHODS: We examined the immunohistochemical distribution of ATP2C1 in normal epidermis and measured the expression of ATP2C1 in cultured keratinocytes following forced detachment from culture dish or following treatment with high concentrations of calcium. Furthermore, we knockdown ATP2C1 expression in cultured keratinocytes by using RNA interference procedure to abrogate cation accumulation in cell organelles. RESULTS: ATP2C1 is specifically localized at the basal cell layer in normal epidermis. Neither detachment of keratinocyte from culture dish nor treatment with high concentrations of calcium suppressed ATP2C1 expression, while both procedures induced differentiation markers, K10 keratin and involucrin. In contrast, knockdown of ATP2C1 induced these differentiation markers of cultured keratinocytes. Furthermore, treatment of keratinocytes with a calcium ionophore, A23187, did not up-regulate differentiation markers of keratinocytes, while a more manganese selective ionophore Br-A23187 up-regulated these differentiation markers. CONCLUSION: Our results suggest that ATP2C1 plays an essential role for basal keratinocytes to keep in the undifferentiated state and that its reduction evokes differentiation and up-localization to suprabasal layers most likely via the manganese starvation in the Golgi apparatus of keratinocytes.

Base Sequence↗

Phase-dependent chronotropic response of the heart during running in humans.

Heartbeat modulation by muscle contraction during rhythmic exercise involving a small muscle mass is phase-dependent, reflecting the timing of the muscle contraction within the cardiac cycle, but it remains unclear whether such modulation occurs during whole body exercise. To determine whether phase-dependent chronotropic changes in the heart would occur during running, we investigated the relationship between R-R interval (RRI) and the timing of vastus lateralis muscle contractions within the cardiac cycle. Seven healthy subjects were examined during high intensity running where the target heart rate was 160 beats . min(-1). The running pitch was made to wax and wane periodically in the neighborhood of the target heart rate to scan the effect of footfall timing within the cardiac cycle on heart period. We found that when muscle contraction occurred early in the cardiac cycle, RRI was reduced from the mean RRI (P<0.05). Conversely, when muscle contraction occurred in the latter half of the cardiac cycle, RRI tended to increase (P>0.05). Thus, the curve reflecting this phase-dependent relationship between heart period and timing of muscle contraction showed a positive slope within the first one-quarter to three-quarters of the cardiac cycle. Our results suggest the existence of a mechanism that provides beat-by-beat regulation of RRI even when it is very short (approximately 375 ms), i.e., a cardio-locomotor synchronization develops during running, when the frequencies of the two rhythms approach one another.

Adult↗

Interpretation of visual field defects respecting the vertical meridian and not related to distinct chiasmal or postchiasmal lesions.

Hemianopia respecting the vertical meridian generally results from a disturbance in the optic chiasm or the postchiasmal visual pathway. We present five unusual patients with visual field defects respecting the vertical meridian that were not related to distinct chiasmal or postchiasmal lesions, as determined by magnetic resonance imaging (MRI). Optic neuritis, plus the influence of the testing algorithm for perimetry, was a possible cause in two cases. The symptoms of one patient with homonymous hemianopia were a functional deficit. In the two other cases, the visual field defects may have been caused by optic disc abnormalities. Although visual field defects respecting the vertical meridian, and without any evidence of distinct disease, are uncommon, neurologists and neuro-ophthalmologists should consider the differential diagnosis if MRI is negative for distinct lesions in the optic chiasm or the postchiasmal visual pathway.

Adult↗

Non-neuronal cholinergic system in human bladder urothelium.

OBJECTIVES: To evaluate the non-neuronal cholinergic system in the isolated human bladder. Recently, several reports have demonstrated that non-nerve-evoked acetylcholine (ACh) release may contribute to various pathophysiologic conditions. METHODS: Human bladders were obtained from 15 patients. Bladder strips with or without urothelium were suspended in an organ bath filled with Krebs-Henseleit solution. ACh release was measured using microdialysis and high-performance liquid chromatography. The contribution of urothelium to non-nerve-evoked ACh release was tested, and the effects of age and elevation of the resting tension (0 to 40 mN) on ACh release were also evaluated. Furthermore, choline acetyltransferase (ChAT) immunohistochemical staining of bladder was performed. RESULTS: Immunohistochemistry showed marked ChAT-positive staining in the urothelium and suburothelial region. Tetrodotoxin-insensitive non-nerve-evoked ACh release occurred and was significantly greater in strips with than without urothelium. The non-nerve-evoked ACh release from strips with urothelium increased with age, and the positive correlation between age and release was significant. Stretching of the strips caused increases in non-nerve-evoked ACh release that was significantly greater in strips with than without urothelium. The stretch-induced release of non-nerve-evoked ACh increased with age. CONCLUSIONS: These data have demonstrated that a non-neuronal cholinergic system is present in the human bladder and that the urothelium/suburothelium partially releases ACh. We found a significant age-related and stretch-induced increase in non-nerve-evoked ACh release. This suggests that the non-neuronal cholinergic system may contribute to the physiology and pathophysiology of human bladder function.

Acetylcholine↗

Symptom assessment tool for overactive bladder syndrome--overactive bladder symptom score.

OBJECTIVES: Overactive bladder (OAB) is a common symptom syndrome with urgency, urinary frequency, and urgency incontinence. To collectively express OAB symptoms, we developed the overactive bladder symptom score (OABSS). METHODS: Four symptoms--daytime frequency, nighttime frequency, urgency, and urgency incontinence--were scored. The weighing score was based on a secondary analysis of an epidemiologic database. Psychometric properties were examined in five patient groups: OAB (n = 83), asymptomatic controls (n = 34), stress incontinence (n = 29), benign prostatic hyperplasia (n = 28), and other diseases with urinary symptoms (n = 26). RESULTS: The maximal score was defined as 2, 3, 5, and 5 for daytime frequency, nighttime frequency, urgency, and urgency incontinence, respectively. The sum score (OABSS 0 to 15) was significantly greater in the patients with OAB (8.36) than in the other patient groups (1.82 to 5.14). The distribution of the OABSS showed a clear separation between those with OAB and asymptomatic controls. The OABSS correlated positively with the individual scores (Spearman's r = 0.10 to 0.78) and quality-of-life scores assessed by the King's Health Questionnaire (Spearman's r = 0.20 to 0.49). The weighted kappa coefficients were 0.804 to 1.0 for each symptom score and 0.861 for OABSS. The posttreatment reduction in the OABSS was consistent with the global impression of patients of the therapeutic efficacy. CONCLUSIONS: The OABSS, the sum score of four symptoms (daytime frequency, nighttime frequency, urgency, and urgency incontinence), has been developed and validated. OABSS may be a useful tool for research and clinical practice.

Aged↗

Monitoring daily living activities of elderly people in a nursing home using an infrared motion-detection system.

We examined whether we could identify activity patterns of elderly people in a nursing home from sensor outputs of an infrared monitoring system. The subjects consisted of three elderly people. A single passive infrared sensor installed on the ceiling of each subject's usual dwelling room provided digital output whenever the subject moved. The subjects' actual daily activities were established from questionnaires with which patients documented their living patterns for each of 7 days. Activities were classed as sleeping, getting up/breakfast, indoor activities/going out, and dinner/going to bed. The mean +/- 2 standard deviations (SDs) of the sensor outputs on each day for each period of indoor activity was used to distinguish between normal and aberrant activities. Days on which sensor outputs exceeded the means +/- 2 SDs were regarded as atypical and were identified for each subject over a 28-day period. We were unable to determine the physical condition of the subjects on these atypical days. We were able to identify the pattern of daily indoor living activities and the duration of each class of activity using sensor outputs and a questionnaire. Days were assumed to be atypical when sensor outputs deviated from the normal pattern.

Activities of Daily Living↗

Resolution of homonymous visual field loss documented with functional magnetic resonance and diffusion tensor imaging.

A 68-year-old man developed right homonymous hemianopic paracentral scotomas from acute infarction of the left extrastriate area. He was studied over the ensuing 12 months with visual fields, conventional MRI, functional MRI (fMRI), and diffusion tensor imaging (DTI). As the visual field defect became smaller, fMRI demonstrated progressively larger areas of cortical activation. DTI initially showed that the lesioned posterior optic radiations were completely interrupted. This interruption lessened in time and had disappeared by one year after onset. fMRI and DTI are innovative measures to follow functional and structural recovery in the central nervous system. This is the first reported application of these imaging techniques to acute cerebral visual field disorders.

Aged↗

Prostaglandin E2 release from isolated bladder strips in rats with spinal cord injury.

AIM: Recent studies have shown that various factors contribute to the increased excitability into the bladder afferent nerves in spinal cord injury (SCI) rats. It has been reported that prostaglandins (PG) act as local modulators of reflex micturition in pathological conditions. In the present study, we measured the amount of PGE2 release from the bladder of chronic SCI rats. METHODS: Spinal cord was transected at the level of T8-9 in adult female Sprague-Dawley rats. After 10 weeks, specimens of the urinary bladder were obtained from SCI rats and sham-injured control rats, and bladder strips were dissected from the bladder. Using an muscle-bath technique and a microdialysis procedure, the dialysate, containing substance released from bladder strips, was collected. Then the amount of PGE2 in the dialysate was measured by radioimmunoassay. RESULTS: Excretion of urinary PGE2 was significantly higher in SCI rats than in control rats. PGE2 release from bladder strips was significantly higher in SCI rats than in control rats. Removal of urothelium caused significant decreases in PGE2 release in both control and SCI rats. Stretches of the bladder strips caused significant resting tension-dependent increases in PGE2 release from the strips with urothelium. CONCLUSIONS: The present data suggest that bladder urothelium partly contributes to the increase in PGE2 release from the bladder, and that bladder distension may cause increases in PGE2 release in SCI rats.

Animals↗

Human epidermal basal cell responses to ultraviolet-B differ according to their location in the undulating epidermis.

BACKGROUND: Exposure of skin to excessive ultraviolet-B (UVB) radiation causes epidermal hyperproliferation that leads to epidermal hyperplasia, however, it is not yet clear exactly how these responses progress. OBJECTIVES: We attempted to clarify the response patterns involved with epidermal hyperproliferation following UVB radiation. METHODS: UVB was irradiated at 2 minimal erythema doses (MED) to human back skin and epidermal morphologic changes were evaluated using in vivo confocal laser microscopy. Skin biopsy specimens were collected from exposed and from non-exposed regions, and were subjected to histochemical and immunohistochemical analysis. RESULTS: The in vivo confocal laser microscopic analysis showed that UVB-induced epidermal hyperplasia was prominent at the epidermal rete ridges. Further, 3 days after UVB exposure, numerous Ki67-positive epidermal cells were observed in the epidermal rete ridges, but not in the epidermis at the top of the dermal papilla. These results suggest that cells highly responsive to UVB exist in the epidermal rete ridges and that their hyperproliferation leads to elongation of the epidermal rete ridges. In contrast, the number of keratin 10-positive basal cells, known as transitional cells, was increased throughout the epidermis, suggesting that an upward migration of keratinocytes from the epidermal basal layer occurred regardless of their location. However, diffusion of melanin to the suprabasal layers was markedly observed in epidermal regions above the dermal papillae, suggesting the occurrence of strong upper cell movement at this position. CONCLUSION: Based on our results, we conclude that differences in keratinocyte responses to UVB radiation exist in cells located in the undulating epidermal basal layer.

Adult↗

VapB-positive Rhodococcus equi infection in an HIV-infected patient in Japan.

Rhodococcus equi, a bacterium present in soil, is a common cause of pneumonia in foals. This organism has been recognized as an opportunistic pathogen in humans, typically causing infection in immunocompromised hosts such as HIV-infected patients and organ transplant recipients. However, human infection with R. equi has not been reported in Japan except in a case involving a laboratory worker. We report the first human case of VapB-positive R. equi pneumonia, which involved an HIV-infected patient living in an urban area in Japan. The patient was treated successfully with 450 mg rifampicin and 600 mg tosufloxacin, even though his CD4+ lymphocyte count at the time of diagnosis was 10/microl. The patient's dogs were suspected in the epidemiology of this infection, but unfortunately we could not isolate the organism from canine-associated specimens in this case. R. equi infections in companion animals have been thought to be very rare, but they may be increasing in dogs. Therefore, further epidemiological research may clarify the prevalence of R. equi infection and the factors predisposing dogs to this infection.

AIDS-Related Opportunistic Infections↗

Effects in vitro and in vivo by apomorphine in the rat corpus cavernosum.

The study was performed to clarify if apomorphine at the level of the rat corpus cavernosum can produce erectile responses or interfere with nerve-induced penile erection. Apomorphine (10(-9)-10(-4) M) exhibited a 10-fold higher potency to relax phenylephrine (Phe)- than endothelin-1 (ET-1)-induced contractions. Relaxant effects of apomorphine in Phe-activated corpus cavernosum did not change tissue levels of cyclic nucleotides, and were unaffected by inhibition of the synthesis of nitric oxide, or by inhibition of the soluble guanylate cyclase. Relaxations by apomorphine of ET-1-contracted rat corpus cavernosum were not influenced by alpha2-adrenoceptor blockade (yohimbine, 10(-7) M), or by the dopamine D1-like receptor antagonist SCH 23390 (10(-6) M). Clozapine (10(-6) M), a proposed dopamine D2-like receptor antagonist, partly reduced apomorphine-induced relaxations, and significantly altered the -log IC50 value for apomorphine. Nerve-induced contractions of the rat corpus cavernosum were attenuated by apomorphine in a concentration-dependent and biphasic manner. Yohimbine (10(-7) M) abolished the biphasic concentration-response pattern. SCH 23390 (10(-6) M) attenuated the inhibitory effects of apomorphine on contractions, and significantly altered the -log IC50 value for the compound. In anesthetized rats (50 mg kg(-1) pentobarbital sodium, 10 mg kg(-1) ketamine), intracavernous apomorphine (100, 300, or 1000 nmol) did not have effects on basal cavernous pressure under resting conditions, and did not affect filling or emptying rates, or peak pressures of the rat corpus cavernosum during submaximal activation of the cavernous nerve. In awake rats, apomorphine produced a maximal number of erections at 300 nmol kg(-1). In the rat isolated corpus cavernosum, pre- and postjunctional effects of apomorphine appear to involve dopamine D1- and D2-like receptors, as well as alpha-adrenoceptors. At relevant systemic doses of apomorphine, peripheral effects of the compound are unlikely to contribute to its proerectile effects in rats.

Animals↗

Age-related alterations in the biochemical and functional properties of the bladder in type 2 diabetic GK rats.

Previous studies have demonstrated that experimental type 1 diabetes induced by streptozotocin causes alterations in the biochemical and functional properties of several receptor systems in the rat bladder. However, the exact mechanism involved in the pathophysiology of voiding dysfunction in type 2 diabetic patients is unknown. Because the GK rat is a widely accepted genetically determined rodent model for human type 2 diabetes, we investigated diabetes-induced changes in the bladder smooth muscle of the GK rats at several time points. Male GK rats and age-matched Wistar rats, as controls, were maintained for 4, 8, 16, and 32 weeks. Contractile responses to KCl, carbachol, ATP, and electrical field stimulation (EFS) were measured by using the isolated muscle bath techniques. Acetylcholine (ACh) release induced by EFS from bladder muscle strips was measured by using high-performance liquid chromatography coupled with a microdialysis procedure. Maximum contractile responses to carbachol and ATP, the release of ACh, and tissue sorbitol levels were similar in bladders from GK and control rats until 8 weeks of age. At 16 weeks of age, however, the contractile responses to carbachol and ATP, and tissue sorbitol levels were increased, and the EFS-induced ACh release was decreased in GK rats compared with controls. Although the maximum contractile responses to EFS were unchanged until 16 weeks of age, they were decreased in 32-week-old GK rats, compared with controls. Our data indicate the presence of age-related alterations in the biochemical and functional properties of the bladder in type 2 diabetic GK rats.

Acetylcholine↗

[A case of leptospirosis caused by Leptospira borgpetersenii serovar sejroe infected in Bali Island, Indonesia].

We report a patient with leptospirosis caused by Leptospira borgpetersenii serovar Sejroe infection on Bali Island, Indonesia. This 33-year-old Japanese man had stayed at a resort hotel on the island from July 8 to July 13 2004. At the hotel, he swam in the pool, walked barefoot, and lied down in the grass. He developed a high fever and headache 7 days after completing his trip, and was admitted to our hospital on July 23. On admission he showed conjunctival suffusion and complained of myalgias. Laboratory findings included granulocytosis and elevated CRP. Plasmodium spp. were not found in blood smears, and no pathogenic bacteria were isolated from blood or fecal cultures. We diagnosed the patient as leptospirosis upon detection of slender coiled organisms with characteristic morphology by darkfield examination of blood sample. Minocycline 100 mg i.v.b.i.d. showed excellent efficacy. A microscopic agglutination test (MAT) during the convalescent stage demonstrated a significant increase in antibodies against L. borgpetersenii serovar Sejroe, confirming the diagnosis of leptospirosis. Despite occurrence of a pandemic of leptospirosis in certain Southeast Asian countries including Indonesia, information concerning pandemic disease is limited. In addition serovars of "imported" cases representing infection in pandemic areas differ widely from those in domestic cases. Adequate laboratory support therefore is crucial for accurate diagnosis of leptospirosis.

Adult↗

Age-dependent plasticity in the superior temporal sulcus in deaf humans: a functional MRI study.

BACKGROUND: Sign-language comprehension activates the auditory cortex in deaf subjects. It is not known whether this functional plasticity in the temporal cortex is age dependent. We conducted functional magnetic-resonance imaging in six deaf signers who lost their hearing before the age of 2 years, five deaf signers who were >5 years of age at the time of hearing loss and six signers with normal hearing. The task was sentence comprehension in Japanese sign language. RESULTS: The sign-comprehension tasks activated the planum temporale of both early- and late-deaf subjects, but not that of hearing signers. In early-deaf subjects, the middle superior temporal sulcus was more prominently activated than in late-deaf subjects. CONCLUSIONS: As the middle superior temporal sulcus is known to respond selectively to human voices, our findings suggest that this subregion of the auditory-association cortex, when deprived of its proper input, might make a functional shift from human voice processing to visual processing in an age-dependent manner.

Adult↗