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Biomedical subjects

H Imai

Publications and source records attributed to H Imai.

At least 19 recordsLinked to original sources
PubMed1995

Effect of chloride on the thermal reverse reaction of intermediates of iodopsin.

Among the intermediates in the bleaching process of iodopsin, a chicken red-sensitive cone visual pigment, the batho and meta I intermediates (batho and meta I) formed at low temperatures revert to the original iodopsin by thermal reactions [Yoshizawa & Wald (1967) Nature 214, 566-571; Imamoto, Imai, Yoshizawa, & Shichida (1994) FEBS Lett. 354, 165-168]. In order to elucidate the relationship between Cl- binding to iodopsin and these reverse reactions, we have prepared a sample of iodopsin whose Cl(-)-binding site is vacant (anion-unbound iodopsin) and compared the thermal reactions of its batho and meta I intermediates with those of Cl(-)-bound (native) and nitrate-bound iodopsins. The reverse reaction from batho is observed in both Cl(-)-bound and anion-unbound iodopsins, while the reaction from meta I is observed only in Cl(-)-bound iodopsin. These results indicate that Cl- binding is indispensable for the reverse reaction from meta I, but not from batho. The reverse reaction from meta I has been further investigated as a function of Cl- concentration, and the dissociation constant of Cl- in meta I is estimated to be approximately 20 mM. This value is about 200 times larger than that of iodopsin (0.1 mM), and close to the physiological Cl- concentration in photoreceptor cells, suggesting that Cl- could be released from the protein moiety during the bleaching of iodopsin.

Animals↗
PubMed1995

Difference in molecular properties between chicken green and rhodopsin as related to the functional difference between cone and rod photoreceptor cells.

Using low-temperature spectroscopy, we have investigated the photobleaching process of chicken green, a green-sensitive cone visual pigment present in chicken retina, and compared it to that of rhodopsin, a rod visual pigment. Like rhodopsin, chicken green converts to all-trans-retinal and opsin through batho, lumi, and meta I, II, and III intermediates. However, all of the intermediates of chicken green except lumi, are less stable than the corresponding intermediates of rhodopsin. While early intermediates, batho and lumi are similar in absorption maxima between chicken green and rhodopsin, the meta intermediates of chicken green are about 20 nm blue shifted from those of rhodopsin. Low-temperature time-resolved spectroscopy was applied to estimate the thermodynamic properties of meta intermediates, and it indicated that the less stable properties of meta II and III intermediates of chicken green originate from the smaller activation enthalpies. The decay of the meta II intermediate of chicken green is greatly suppressed when a chicken green sample is irradiated at alkaline conditions while the net charge becomes similar to that of rhodopsin at neutral conditions. These results strongly suggest that the functional properties of chicken green that are different from those of rhodopsin are regulated by the dissociative amino acid residue(s).

Avian Proteins↗
PubMed1995

Age-related change in redox state of human serum albumin.

Human serum albumin (HSA) is the mixture of human mercaptalbumin (HMA, reduced form) and human nonmercaptalbumin (HNA, oxidized form). We developed a rapid and concise HPLC system to obtain the clear resolution of HSA into HMA and HNA, using an Asahipak GS-520H column. The mean value of the fraction of HMA (f(HMA)) for healthy young male subjects was 0.76 +/- 0.04 (n = 54). However, the f(HMA, 60-90) value for healthy elderly subjects (where the numbers in brackets indicate the range of ages) was 0.48 +/- 0.06 (n = 183). In healthy elderly subjects, f(HMA) was significantly lower than in healthy young male subjects, indicating that HSA in the elderly becomes more oxidized than in the young subjects. Consequently, we suggest that one of the important functions of serum albumin could be to participate in the maintenance of a constant redox potential in the extracellular fluids, thus securing a certain redox buffer capacity. f(HMA) on HSA might reflect this redox buffer capacity with age.

Adult↗
PubMed1995

Purification and low temperature spectroscopy of gecko visual pigments green and blue.

We purified two kinds of visual pigments, gecko green and gecko blue, from retinas of Tokay geckos (Gekko gekko) by two steps of column chromatography, and investigated their photobleaching processes by means of low temperature spectroscopy. Absorption maxima of gecko green and blue solubilized in a mixture of 3-[(3-cholamidopropyl)dimethylammonio]-1- propanesulfonate (CHAPS) and phosphatidylcholine were 522 and 465 nm, respectively, which are close to those observed in the photoreceptor cells. Low temperature spectroscopy identified six intermediates in the photobleaching process of gecko green; batho (lambda max = 569 nm), BL (lambda max = 519 nm), lumi (507 nm), meta I (approximately 486 nm), meta II (approximately 384 nm), and meta III intermediates (approximately 500 nm). In contrast to the high similarity in amino acid sequence between gecko green and iodopsin [Kojima, D., et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 6841-6845], the batho-green did not revert thermally to original gecko green but converts to the next intermediate. The photobleaching process of gecko blue was investigated by low temperature spectroscopy, and three intermediates, meta I (lambda max = approximately 470 nm), meta II (lambda max = approximately 370 nm) and meta III (lambda max = approximately 475 nm), were identified. A comparative study on the thermal behavior of meta intermediates revealed that the thermal stability of meta II intermediate of both of the gecko visual pigments is lower than that of metarhodopsin II. The result supports the idea that both the gecko visual pigments are cone-type ones.

Animals↗
PubMed1995

A combination of livedo racemosa, occlusion of cerebral blood vessels, and nephropathy: kidney involvement in Sneddon's syndrome.

A 59-year-old woman with retinal vein thrombosis and livedo racemosa had hematuria (4+) and proteinuria (1.7 g/day). Skin biopsy showed swollen blood vessel walls with infiltration of mononuclear cells, which were compatible with livedo racemosa (vasculitis). Magnetic resonance imaging (MRI) of the brain demonstrated multiple lacunar infarctions in the basal ganglia and white matter. Renal biopsy showed that small round cells had infiltrated into the interstitium, and a reticular structure was observed in the glomerular hilus. An amorphous substance composed of a single cell was present in the glomerular capillary lumen. Immunofluorescent study demonstrated the deposition of only IgA, in a segmental pattern differing from the diffuse global mesangial pattern seen in IgA nephropathy. After combined therapy including 40 mg/day prednisolone, 50 mg/day cyclophosphamide, antiplatelet drug, and anticoagulant was started, proteinuria and hematuria improved to 0.5 g/day and 2+, respectively, at the time of discharge. Sneddon's syndrome is a rare entity characterized by livedo racemosa and cerebrovascular lesions. In our patient with livedo racemosa, occlusion of cerebral blood vessels, and nephropathy with segmental immunoglobulin A (IgA) deposition, no antiphospholipid antibodies were detected on routine examination. Dermatologists, neurologists, psychiatrists, and nephrologists should be aware of the existence of Sneddon's syndrome with nephropathy (LI-O-N).

Antibodies, Antiphospholipid↗
PubMed1995

Microsatellite instability in human prostate cancer.

Microsatellite instability (MSI) was examined at 36 loci, and found in 9 (43%) of the 21 prostatic cancers. A loss of heterozygosity had occurred in five cases (24%). MSI did not correlate with clinical stage, but might play a role in the development of a subset of prostate cancers.

Adult↗
PubMed1995

Non-muscle myosin as target antigen for human autoantibodies in patients with hepatitis C virus-associated chronic liver diseases.

Three patients with hepatitis C virus (HCV)-related chronic liver disease were shown to have autoantibodies strongly reacting with cytoskeletal fibres of non-muscle cells. The heavy chain of non-muscle myosin microfilament was the main target for those autoantibodies, as determined by (i) cell and tissue immunofluorescence studies showing colocalization with an anti-myosin antibody prototype; (ii) primary reactivity in immunoblotting with a 200-kD protein, using either MOLT-4 cells, human platelets, or affinity-purified non-muscle myosin as antigen extract; and (iii) immunoblotting of similar immunoreactive fragments in papain-digested MOLT-4 cell extracts, by using those human sera and antibody prototype. Autoantibodies to non-muscle myosin heavy chain were not previously reported in patients with chronic liver diseases, especially in those associated with HCV infection.

Aged↗
PubMed1995

Diagnosis and treatment of brainstem abscess using magnetic resonance imaging and microsurgical aspiration--case report.

A 6-year-old boy presented with a pontine abscess initially misdiagnosed as brainstem glioma, but he deteriorated rapidly and developed new symptoms of respiratory distress. Magnetic resonance (MR) imaging revealed a rapidly growing mass lesion in the pons. Microsurgical evacuation of the abscess via a suboccipital retromastoid approach resulted in neurological improvement and resolution of the lesion on MR images. Brainstem abscess can be successfully treated with early, accurate diagnosis based on MR imaging and appropriate microsurgical and antibiotic management.

Brain Abscess↗
PubMed1995

Selenium levels and glutathione peroxidase activities in blood in an andean high-altitude population.

Selenium (Se) levels in blood (whole blood, erythrocytes and serum) and blood glutathione peroxidase (GSH-Px) activity were investigated in people living at high altitude in Bolivia (4,000 m above sea level). These parameters were compared to those of people living at low altitude (300 m above sea level). The Se levels in whole blood of the high-altitude subjects did not differ significantly from those of the low-altitude subjects. However, the Se levels in erythrocytes were significantly lower in the high-altitude subjects than in the low-altitude subjects, whereas serum Se levels were higher in the high-altitude subjects than in the low-altitude subjects. GSH-Px activity (Unit/g Hb) was significantly lower in the high-altitude subjects than in the low-altitude subjects. The mean corpuscular Hb concentration (MCHC), an indicator of the age of erythrocytes, in the high-altitude subjects was significantly higher than in the low-altitude subjects. These results show that the GSH-Px activity in the blood of the high-altitude subjects is relatively low. This may be due to their aged erythrocytes and/or to relatively low Se intake in the high-altitude population compared with low-altitude population.

Adolescent↗
PubMed1995

[Semantic/syntactic priming effects and their processing stages].

Three priming experiments were conducted to investigate associative and syntactic information processing in the Japanese language. Unlike in English, associative relation and syntactic plausibility can be manipulated independently. Subjects were given either a lexical decision or naming task because previous studies suggest that these tasks are sensitive to different processing stages. Two prime-target SOAs. 250 ms and 700 ms, were used. The results revealed that syntactic plausibility of associated prime-target pairs was processed differently from that of unassociated ones. When prime-target pairs were unassociated, syntactic plausibility priming was found with the 700 ms SOA in the lexical decision task, but no priming was found in the naming task. This result supports the previous claim that syntactic information is processed post-lexically. In contrast, when prime-target pairs were associated, syntactic plausibility priming was found both with 250 ms and 700 ms SOAs not only in the lexical decision but in the naming task. This suggests that syntactic plausibility of associated prime-target pairs is processed at the lexical rather than post-lexical stage.

Adult↗
PubMed1995

[Endovascular treatment of cerebral vasospasm with intra-arterial papaverine infusion].

Thirty-one cases of cerebral vasospasm following subarachnoid hemorrhage were treated with intraarterial papaverine infusion. Symptomatic cases were nineteen, and asymptomatic cases were twelve. Papaverine (120 mg/saline 50 ml, 30 min) was injected superselectively to vasospastic vessels through a microcatheter. The rate of symptomatically improved cases was 63% initially, but about two thirds of those cases had recurrence within a day. The 63% of symptomatic cases showed infarction in spite of papaverine infusion. Three cases of recurrent vasospasm after intra-arterial papaverine underwent PTA and showed good dilatation of vasospastic vessels. The complications of our intra-arterial papaverine were hypotension in two cases, convulsion in one case and transient disturbed consciousness in one case. We experienced no fatal complications. Overall outcome was ADL1 (19%), ADL2 (25%), ADL3 (44%), ADL4 (0%), ADL5 (6%), and death (6%). Since the effect of intra-arterial papaverine infusion is of short duration and weak, combination of PTA and papaverine may be necessary. It is recommended to use papaverine for vasospasm in distal arteries such as M2, A1, A2, and to carry out PTA for proximal arteries such as ICA and M1.

Adult↗
PubMed1995

Streptococcal pneumoniae polysaccharide increases IgA-class antibody activity under the immunological memory of a protein antigen: two signals on experimental IgA nephropathy.

We designed the following experiment in order to clarify the factors that induce a hyper-immune state of IgA. Six-week-old Balb/c mice were immunized with bovine gammaglobulin (BGG) at 0 and 2 weeks, followed by the administration of phosphorylcholine-BGG (PC-BGG) at 3 and 5 weeks to obtain an immunological memory. At 6 weeks, we divided the mice into three groups: one was a saline group used as a control, another was a PC-BGG group used to investigate T-cell dependent antigen, and the last was a streptococcal pneumoniae polysaccharide (R36A) group used to investigate T-cell independent antigen. We compared the antibody activity in response to BGG, and glomerular immune deposition among the groups. In the control group, antibody activities did not change, and all stainings on glomerular immune deposits were negative. In the PC-BGG group, IgG-class antibody activity was significantly suppressed (p < 0.05), but IgA- and IgM-class antibodies were not affected. The intensity of glomerular deposition of IgM was level one positivity (TFS: 116.7 +/- 20.2 (mean +/- SD)). In the R36A group, polysaccharide produced significant increases (almost four times) in IgA-class and IgM-class antibody activity under the condition of immunological memory (IgA: p < 0.05, IgM: p < 0.005). The intensity of IgA was between weak and level one positivity (TFS: 60.8 +/- 6.3), but the intensity of IgM was weak positive (TFS: 36.7 +/- 10.4). This became a predominant glomerular deposition of IgA in the R36A group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

IgA nephropathy associated with hyper IgAnemia, psoriasis or pustulosis and ossification.

This is a report on two cases of IgA nephropathy associated with psoriasis vulgaris, having hyper IgAnemia (above 500 mg/dl) and ossification. Case 1 is a 47-year-old woman with a 7-year history of psoriasis vulgaris, and case 2 is a 57-year-old man with a 17-year history of this disease. IgA was 526 and 1,356 mg/dl, respectively. HLA analysis showed A2, A26 (10), Bw62 (15), Bw46, Cw3, DRw12 (5), and DRw8 in the former, and A2, A11, B13, Bw46, Cw11, DR4, and DRw8 in the latter. Renal biopsy specimens disclosed mild mesangial proliferative glomerulonephritis and moderate mesangial proliferative glomerulonephritis with predominant IgA deposition in mesangial area, respectively. A bone-scintigraphy revealed a high uptake of radioisotopes in the left shoulder, the vertebra, the sacroiliac joint, both sides of the knees and ankles, and the sterno-cost-clavicular area. An X-ray study showed ossification of the posterior longitudinal ligament (OPLL) in the former, and ankylosing spinal hyperostosis (ASH) in the latter. A review of the literature discloses three other case reports of hyper IgAnemia, IgA nephropathy, psoriasis or pustulosis, and ossification. The alertness of dermatologists, orthopedic surgeons, rheumatologists, and general practitioners will be required to attain to a more frequent diagnosis of the above combination.

Female↗
PubMed1995

[A 51-year-old man with early onset parkinsonism].

We report of 51-year-old man with early onset parkinsonism. The patient was well until 38 years of age, when he noted a difficulty in the use of his right leg; this difficulty improved after he received a medicine from his physician. He did not take medicine regularly, and he noted difficulty in standing up from a chair and in rolling over at age 40. Tremor was not a feature, but he noted slowness in his movements at age 42; at age 49, he noted diurnal fluctuation in his symptoms and at times he experienced hallucination. He was admitted to our hospital in September of 1992 for the first time when he was 50-year-old. At that time, neurologic examination revealed an alert and somewhat bradyphrenic man; Hasegawa dementia rating scale was 20/30. Cranial nerves were intact except for masked face and small voice. He showed stooped posture and small step gait cogwheel rigidity was noted in the four limbs more on the left; tremor was absent. Deep reflexes were within normal range and the sensation was intact. As he showed diurnal fluctuation in his symptoms, his medication was switched to levodopa 3,000 mg/day without a peripheral decarboxylase inhibitor. He was discharged for out patient follow up. But he did not take drugs regularly, and his neurologic condition deteriorated; he was admitted to another hospital. Neurologic examination at that time was essentially similar to that of his first admission to our hospital, except that he showed more severe rigidity and akinesia; again tremor was not detected. His cranial CT scan showed a mild ventricular dilatation without cortical or brain stem atrophy. During his hospital stay, he developed episodes of oculogyric crisis during peak dose of levodopa, and orthostatic hypotension. He developed pneumonia and expired on October 28, 1993. He was discussed in a neurological CPC, and the chief discussion arrived at the conclusion that the patient had early onset Parkinson's disease of Lewy body type. As differential diagnoses, early onset parkinsonism without Lewy body, pure form of diffuse Lewy body disease, pallidoluysian atrophy, and other conditions were considered; however, all of those possibilities were excluded. Early onset parkinsonism without Lewy body would have much earlier onset than this patient, and diffuse Lewy body disease would show more profound dementia 13 years after the onset. Pallidoluysian atrophy would be complicated with some dystonic features. Post-mortem examination showed marked discoloration and degeneration of the substantia nigra. The degeneration was most prominent in the ventrolateral tier of the substantia nigra.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain↗
PubMed1995

[Neurological involvements with transient gait disturbance in subacute phase of Kawasaki disease; a case report].

A 1-year-and-9-months old boy with gait disturbance during the 3rd week of Kawasaki disease (KD) was described. He had been previously healthy, and developed high fever and rash. The diagnosis of KD was based on 5 of 6 major criteria on the 3rd clinical day. He was initially treated with intravenous gamma-globulin 400 mg/kg/day for five days. On the 17th clinical day, the patient developed gait disturbance after most clinical signs disappeared. His gait was wide- based and unstable. Generalized hypotonia with poor traction response was also seen. Pyramidal tract signs including exaggerated patellar and Achilles tendon reflexes and positive bilateral Mendel-Bechterew reflex were presented. Cerebrospinal fluid was normal. Brain CT, MRI, and 123I-IMP SPECT images were normal without broad hemorrhage or infarction of the cerebral parenchyma. Gait disturbance recovered spontaneously within one month without any sequelae.

Central Nervous System Diseases↗
PubMed1995

[A 57-year-old woman with gait disturbance, headache, character change, convulsion, and coma].

We report a 57-year-old woman with progressive gait disturbance, headache, character change, convulsion and coma. She was well until 55 years of age, when she noted an onset of unsteady gait. At times she experienced transient weakness in her right hand, which was followed some difficulty in articulation. She was admitted to our service for the work up on April 6, 1992. Neurologic examination at that time revealed an alert Japanese lady in no acute distress. She was oriented to all spheres, however, she was somewhat bradyphrenic and had some disturbance in recent memory. Higher cerebral functions appeared intact. The visual acuity and visual fields were normal as were the optic fundi. Pupils were round and isocoric reacting promptly to light. Ocular movement was full, however, horizontal nystagmus was noted upon right lateral gaze. The sensation of the face was intact. She showed right facial paresis of the central type. Hearing was intact. She showed slurred speech and some difficulty in swallowing. The tongue was deviated to the right. Her gait was wide based and unsteady; tandem gait was difficult, however, walking on toes and on heels were performed well. No cerebellar ataxia was noted, but she showed some clumsiness in her right hand. Deep reflexes were symmetric and normally reactive; plantar response was extensor bilaterally. Sensation was intact; no meningeal sign was elicited. Routine laboratory work up was unremarkable; the CSF was under a borderline pressure (180 mmH2O) and contained 39 mg/dl of protein and 59 mg/dl of sugar. Cranial CT scan revealed diffuse low density areas involving bilateral cerebral white matter as well as the brain stem; MRI revealed high signal intensity lesions in those areas; gadolinium enhancement was negative; cortical sulci were effaced and the anterior part of the left lateral ventricle was compressed without deviation of the midline structure. The patient was treated with steroid pulse therapy without effect. She was discharged for out patient follow up, however, she developed a convulsion which was followed by loss of consciousness, and was admitted again to our service. She had never gained consciousness after this episode, and remained in the state of akinetic mutism. Follow-up CT and MRI did not show much change, although the area of high signal density lesions slightly enlarged on June 1, 1993. Her clinical course was complicated by drug induced bone marrow suppression and nephrotic syndrome. She expired on September 8, 1993 after developing sudden drop of blood pressure and bradycardia.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain Neoplasms↗