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Biomedical subjects

H Yaguchi

Publications and source records attributed to H Yaguchi.

At least 37 records · Page 2Linked to original sources
PubMed2000

Technique to investigate the temporal phase shift between L- and M-cone inputs to the luminance mechanism

We describe a technique to estimate the intrinsic phase shift between long-wavelength-cone (L-cone) and middle-wavelength-cone (M-cone) signals in the luminance mechanism with minimal contamination by chromatic mechanism(s). The technique can also estimate, simultaneously with the phase shift, the weight ratio of L and M cones for the luminance mechanism. We measured motion identification thresholds for a 1.0 cycle/deg, 12.0-Hz sinusoidal grating representing different vector directions in L- and M-cone contrast space. The physical phase of the L- and M-cone signals was varied over a broad range between -150 deg and +150 deg to investigate the effect on the threshold contours. The slope of the threshold contour in cone contrast space varied as a function of the physical phase. Estimates of the intrinsic phase shift between L and M cones are based on the change in slope of the threshold contour. The estimates are consistent with previous reports and show that whereas the L-cone signal lags behind the M-cone signal by approximately 35 deg for an orange background, the M-cone signal lags behind the L-cone signal by approximately 8 deg for a green background.

Journal Article↗
PubMed2000

[A case of brain stem infarction with bilateral hearing loss].

The study case was a 66-year-old man who had bilateral neurosensory hearing impairment due to brain stem infarctions. He noticed mild hearing loss, frequent vertigo and tinnitus. About one month later, his hearing took a sudden turn for the worse, and he suffered from dysarthria, dysphagea and abasia. Neurological examination revealed pseudobulber palsy, left hemiparesis, cerebeller ataxia, disturbance of pain and temperature sensation on the right face and left side of the body. Brain stem auditory evoked potentials (BAEPs) showed a delayed small wave V with the abscence of previous waves on the right side and no significant waves on the left side. Brain magnetic resonance images (MRI) revealed infarctions in the bilateral middle cerebellar peduncles, including in the right lateral portions of pons, and the right lower pontine base. We believe that not only peripheral, but also central auditory pathways adjacent to infarctions were damaged. Magnetic resonance angiography (MRA) showed severe stenosis or occlusion of left vertebral artery and basilar artery. We concluded that hypoperfusion of the vertebrobasilar artery territories caused ischemia of the cochlear nerve and the auditory tracts in the brain stem, which resulted in bilateral hearing loss.

Aged↗
PubMed2000

[Polymyositis with marked paravertebral muscle atrophy in patients with primary biliary cirrhosis].

We reported two patients with polymyositis (PM) associated with primary biliary cirrhosis (PBC) who noticed head-drop as the incipient symptom. Muscle computed tomography showed marked hypodensity in the paravertebral muscles as compared with limb muscles. Patient 1, a 48-year-old female, was admitted in our hospital for the examination because of her neck and proximal limb muscle weakness, increasing fatigability, and abnormal serum liver and muscle enzyme levels. She felt her throat was so dry at age 39, and she noticed weight loss at age 41 and head-drop at age 42. A diagnosis of PM was made from symmetrical proximal limb muscle weakness, elevated creatine kinase (CK) level, and the electromyographic and muscle biopsy findings. Her illness was also diagnosed as PBC because of the increased serum alkaline phosphatase and IgM immunoglobulin levels, and liver biopsy findings. The anticentromere antibody titer was positive, though the antimitochondrial antibody titer negative. The HLA typing was DR 4, DR 8, DR53, DQ 4, DQ 6, DRB 1 (0405/0803). She was placed on 60 mg of prednisolone/day for PM and 300 mg of ursodeoxycholic acid/day for PBC. Patient 2, a 49-year-old female, presented with proximal limb muscle weakness and head-drop. Serum CK, alkaline phosphatase and IgM immunoglobulin levels were increased. The antimitochondrial antibody titer was positive. She began to have 60 mg of prednisolone/day, and 50 mg of azatioprine/day and 300 mg of ursodeoxycholic acid/day were subsequently added. PM associated with PBC seems to be rare, because only 21 cases have been described in literature. In those patients, marked paravertebral muscle atrophy has never been described. Further study is necessary to examine whether or not the preferential paravertebral muscle involvement is a striking and diagnostic finding for PM with PBC.

Atrophy↗
PubMed1999

Effect of high-density extremely low frequency magnetic field on sister chromatid exchanges in mouse m5S cells.

The induction of sister chromatid exchanges (SCEs) was evaluated in the cultured mouse m5S cells after exposure to extremely low frequency magnetic field (ELFMF; 5, 50 and 400 mT). Exposure to 5 mT and 50 mT ELFMF led to a very small increase in the frequency of SCEs, but no significant difference was observed between exposed and unexposed control cells. The cells exposed to 400 mT ELFMF exhibited a significant elevation of the SCE frequencies. There was no significant difference between data from treatments with mitomycin-C (MMC) alone and from combined treatments of MMC plus ELFMF (400 mT) at any MMC concentrations from 4 to 40 nM. These results suggest that exposure to highest-density ELFMF of 400 mT may induce DNA damage, resulting in an elevation of the SCE frequencies. We suppose that there may be a threshold for the elevation of the SCE frequencies, that is at least over the magnetic density of 50 mT.

Animals↗
PubMed1999

Lipoprotein lipase promoting agent, NO-1886, modulates adrenal functions: species difference in effects of NO-1886 on steroidogenesis.

A novel compound, NO-1886, which possesses a powerful lipoprotein lipase activity-increasing action, induces hypertrophy of adrenals in rats and hyperplasia of cortical cells in dogs. However, these effects were not observed in monkeys. We examined the effects of NO- 1886 on steroid hormone production by adrenocortical cells to clarify its effects on adrenal steroidogenesis. NO-1886 did not inhibit the steroid synthetic enzymes, including 3beta-hydroxysteroid dehydrogenase, 21-hydroxylase, 11beta-hydroxylase, or cholesterol side-chain cleavage enzymes. However, NO-1886 affected steroid production from adrenocortical cells in rats, dogs, monkeys, and humans in in vitro studies. These effects were almost completely reversed by the addition of 25-hydroxycholesterol or low-density lipoproteins to the reaction medium, but not reversed by the addition of high-density lipoproteins. These results suggest that NO-1886 affects the cholesterol pathways within the adrenocortical cells and inhibits steroidogenesis, causing a reduction of steroid hormone release from adrenocortical cells and resulting in hypertrophy of adrenals via feed-back mechanisms. However, its effect is not apparent in animals that use low-density lipoproteins as a source of adrenocortical steroidogenesis.

Adrenal Cortex↗
PubMed1999

Selective cone suppression by the L-M- and M-L-cone-opponent mechanisms in the luminance pathway.

We investigated how transient changes of background color influence the L- and M- (long- and middle-wavelength-sensitive-) cone signals in the luminance pathway. Motion identification thresholds were measured for a drifting sinusoidal grating (1 cycle/deg) modulated along different vector directions in L- and M-cone contrast space. The color of a central 4-deg-diameter region was briefly altered (500 ms) by incrementing or decrementing either L- or M-cone excitation. Incrementing L-cone and decrementing M-cone excitation produced a field that appeared reddish relative to the yellow surround. Likewise, incrementing M-cone and decrementing L-cone produced a field that appeared greenish. Motion identification thresholds were obtained on the yellow field following the brief color transitions. The results show that the threshold for the L-cone direction was selectively elevated by the background substitution of incrementing L-cone and decrementing M-cone excitation (shift toward reddish color). The same substitution, however, did not affect the threshold in the M-cone direction. Similarly, the threshold for the M-cone direction was selectively elevated by the background substitution of incrementing M-cone, decrementing L-cone excitation (shift toward greenish) without affecting the threshold in the L-cone direction. Experiments using the motion quadrature paradigm confirmed that these effects occur within the luminance mechanisms. These results indicate that the activation of L-on plus M-off signals suppresses the L-cone signal and that the activation of L-off plus M-on signals suppresses the M-cone signals in the luminance pathway. We propose a retinal model based on the experimental results.

Color↗
PubMed1998

Bladder cancer in a patient on long-term haemodialysis.

We report a case of bladder cancer on long-term haemodialysis. The relationship between bladder cancer and haemodialysis, and the necessity of periodic cytology of bladder washing are discussed.

Carcinoma, Transitional Cell↗
PubMed1998

The effect of triathlon on urinary excretion of enzymes and proteins.

In order to investigate the effect of triathlon and renal function of normal subjects, we evaluated the excretion of urinary enzymes and proteins before and after triathlon. From 6 subjects samples were obtained 24 hours after the first urine collection. We performed quantification of urinary total protein, beta2-microglobulin (beta2-M), N-acetyl-beta-D-glucosaminidase activity (NAG), and concentration of urinary creatinine from each participant. There was a significant increase in urinary total protein excretion immediately after triathlon (p<0.01). The urinary beta2-M and NAG excretions after triathlon were higher than the initial values. Post-exercise proteinuria in one subject persisted until the next morning, whereas the increased excretion of urinary beta2-M and NAG returned to the pre-exercise level at least 24 hours after triathlon. It appears to be reasonable to presume that glomerular damage may persist in some subjects who do heavy exercise.

Acetylglucosaminidase↗
PubMed1998

Involvement of high density lipoprotein as substrate cholesterol for steroidogenesis by bovine adrenal fasciculo-reticularis cells.

Adrenocorticosteroids are known to be synthesized from cholesterol which may arise from de novo synthesis or from the uptake of low-density lipoproteins (LDL) or high-density lipoproteins (HDL). LDL is reported to be a main substrate for corticosteroid synthesis by bovine adrenocortical cells, although the role of HDL, which is well known to be used for steroid biosynthesis in rat adrenals, is still obscure. Therefore, we examined the role of HDL in the regulation of corticosteroidogenesis in bovine adrenals in order to clarify whether or not HDL was selectively utilized for corticosteroid synthesis in vitro. The present data demonstrated that HDL and LDL increased cortisol production in a dose-dependent manner in bovine adrenocortical cells in vitro, and also that HDL cholesterol increased cortisol production significantly higher than LDL cholesterol did. Addition of adrenocorticotrophic hormone (ACTH) with HDL to the incubation media enhanced much higher cortisol production than that with LDL in short time incubation. The present data also demonstrated that uptake of 125I-HDL was significantly greater than that of 125I-LDL. Thus, HDL rather than LDL is thought to be the preferred lipoprotein as a source of steroidogenic substrate cholesterol in bovine adrenal fasciculo-reticularis cells.

Animals↗
PubMed1998

Down's syndrome associated with seminoma in undescended testis.

In patients with Down's syndrome, the coincidence of testicular cancer with the syndrome has recently been emphasized. We present a case of Down's syndrome associated with seminoma in undescended testis and discuss the relationship between testicular cancer and Down's syndrome.

Adult↗
PubMed1998

Esophageal strictures in children with recessive dystrophic epidermolysis bullosa: experience of balloon dilatation in nine cases.

BACKGROUND: Recessive dystrophic epidermolysis bullosa is a rare disorder characterized by extreme vulnerability of the squamous epithelium and mucous membranes. Minor trauma such as is caused by swallowing solid food is followed by blistering and scarring. Stricture formation at the pharyngoesophageal junction (C6 or C7) is the severest complication of this disease. METHODS: We evaluate the effectiveness of Microvasive Rigiflex balloon dilatation and extensive nutritional support as a primary treatment for this condition. Nine of 21 recessive dystrophic epidermolysis bullosa patients developed esophageal strictures at the level of the pharyngo-esophageal junction (C6). We treated them with intensive nutritional therapy followed by balloon dilatation, which produces longitudinal pressure and provides prompt relief from esophageal stricture. Eleven balloon dilatations have been performed in 9 patients. RESULTS: All patients had poor physical development and were severely malnourished; extensive nutritional support was required before treatment could begin. Balloon dilatation was performed once in seven patients and twice in two patients. No recurrent stricture formation was observed after balloon dilatation. CONCLUSION: Intensive nutritional support followed by balloon dilatation is the first choice of treatment for esophageal strictures complicating recessive epidermolysis bullosa. By following this regime, invasive surgery can be avoided.

Adolescent↗
PubMed1998

The expression of endothelin-1 and its binding sites in mouse skin increased after ultraviolet B irradiation or local injection of tumor necrosis factor alpha.

Endothelin (ET)-1 is a 21-amino acid peptide which has vasoconstrictor and growth regulatory activity. Recently, cultured keratinocytes have been reported to express ET-1 and its receptor when irradiated by ultraviolet (UV) B. In order to further understand the role of ET-1 in vivo during UVB-induced inflammation, we examined the localization, intensity and time course of the expression levels of ET-1 and its binding sites in UVB-exposed BALB/c mouse skin. Frozen and paraffin sections prepared from mouse skin 48 h after treatment with UVB irradiation (0.36 or 0.72 J/cm2) or after injection with tumor necrosis factor (TNF)-alpha (1.0 microgram) or interleukin (IL)-1 alpha (0.05 microgram) were incubated with monoclonal anti-ET-1 IgG and then visualized by peroxidase staining. In normal skin, faint ET-1 immunoreactivity was observed in the epidermis, pilosebaceous structures and blood vessels. Upon exposure to UVB irradiation or administration of TNF-alpha injection or IL-1 alpha injection, such immunoreactivity was found to be significantly enhanced. Subsequently, the frozen sections were incubated with 125I ET-1 for 30 min, and visualized by autoradiographic technique. In normal skin, ET-1 weakly bound to the skin, while UVB irradiation and TNF-alpha injection significantly enhanced ET-1 binding in the epidermis, pilosebaceous structures and blood vessels. Time course experiments (1, 2, 4 and 7 days) indicated that ET-1 immunoreactivity and ET-1 binding peaked 1 or 2 days after UVB irradiation or TNF-alpha injection. These results suggest that the up-regulated expression of ET-1 and its binding sites in the epidermis and pilosebaceous structures may act as an autocrine/paracrine factor during UVB-induced inflammation.

Animals↗
PubMed1998

A study of the efficacy of plasmapheresis for the treatment of drug induced toxic epidermal necrolysis.

The efficacy of plasmapheresis for the treatment of toxic epidermal necrolysis (TEN) in our patient and related reports in the literature were examined. The patient, a 41-year-old female, was diagnosed as having drug (Sedes-G [isopropylantipyrin, arylisopropylacetoureid, and phenacetinum]) induced TEN. Upon admission to our hospital, extensive corticostroid therapy was initiated. After 6 days, because more than 90% of the patient's body surface was affected by TEN, it was concluded that the patient was unresponsive to corticosteroid therapy. Double filtration plasmapheresis (DFPP) was therefore begun. After 2 sessions of DFPP, extensive reepithelialization rapidly occurred, and after 3 sessions of DFPP, the improvement was dramatic. The patient's condition had almost healed during 1 month's hospitalization. It has been reported in the literature that 22 patients with drug induced TEN have been treated with plasmapheresis. The mortality rate of 23 patients, including our patient, was 17.4%. The rate of effectiveness of plasmapheresis on drug induced TEN is 82.6%. It appears that some kind of necrolytic factors were removed by the plasmapheresis. This suggests that plasmapheresis may be an effective treatment for drug induced TEN.

Adult↗
PubMed1998

[A case of pure agraphia due to left parietal lobe infarction].

We reported a case of a 63-year-old right handed man with pure agraphia due to the left parietal lobe infarction. The characteristics of agraphia in the patient were as follows. 1) The written letters were generally recognizable and well formed. 2) He succeeded in pointing to single Kana letter named by the examiner from the Japanese syllabary, but missed in pointing to Kana words. 3) Further, it took more time for the patient to point to even single Kana letter than for the control. 4) Most errors in Kana writing was substitution. Errors in Kanji writing are partial lacking or no response. But his ability in Kanji writing was facilitated by visual cues. He was unable to describe the Hen (a left-hand radical) and Tsukuri (the body) of some Kanji letters and to name some Kanji letters when their Hen and Tsukuri were orally given. We classified pure agraphia into two types out of some references. In one type (Type 1), letters in writing are poorly formed, but the ability to make words with the methods other than writing, for example spelling with anagrams or typing are preserved. In another type (Type 2), letters in writing were well-formed, but spelling with anagrams or typing were abnormal. Type 1 agraphia could result from the only deficit of graphic motor engram, while type 2 agraphia could be caused by the deficits other than graphic motor engram. Agraphia in this case belongs to the type 2. The features of agraphia in this case suggested that his agraphia was caused by a disorder in recalling graphemes of letters, and in arranging at least of Kana-letters.

Agraphia↗
PubMed1997

Efficacy of enalapril after ineffective theophylline treatment on erythrocytosis after renal transplantation.

Erythrocytosis represents a common complication in renal allograft recipients. Traditional therapies including phlebotomy and bilateral native nephrectomies are cumbersome for both the clinical personnel and the patient. Recently, pharmacological agents such as angiotensin converting enzyme inhibitor and theophylline have been proposed as effective therapies for post-transplant erythrocytosis (PTE). We have treated a PTE patient successfully with enalapril without any side effects and renal dysfunction after theophylline treatment showed no improvement in PTE. A decline in Ht levels was independent of the changes in Epo levels during enalapril treatment. Although the mechanism underlying the beneficial effect of enalapril remains undetermined, enalapril is recommended for the initial treatment of PTE.

Adenosine↗
PubMed1997

Plasmapheresis for the treatment of pemphigus vulgaris and bullous pemphigoid.

Forty-two cases of pemphigus vulgaris (PV) and bullous pemphigoid (BP) were treated with plasmapheresis by one of 3 techniques: centrifugation, double filtration plasmapheresis (DFPP), or a combination of the two. Each plasmapheresis resulted in a rapid reduction in the autoantibody titer and an improvement in clinical symptoms, thereby allowing a lower dose of corticosteroid to be administered and remission to be achieved. These findings suggest that plasmapheresis is an effective treatment for PV and BP patients who have been unresponsive to conventional therapy, for those for whom conventional drugs are contraindicated due to complications, and for those who show severe clinical manifestations.

Autoantibodies↗
PubMed1997

Adrenal myelolipoma with abdominal pain.

We report a case of adrenal myelolipoma with abdominal pain. Preoperative diagnosis was correctly made by computed tomography and magnetic resonance imaging. We have reviewed the literature and discuss the contribution of modern imaging techniques to the diagnosis of this tumor.

Abdominal Pain↗