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Biomedical subjects

K Sakamoto

Publications and source records attributed to K Sakamoto.

At least 271 records · Page 15Linked to original sources
PubMed1998

Two visual pigments in a single photoreceptor cell: identification and histological localization of three mRNAs encoding visual pigment opsins in the retina of the butterfly Papilio xuthus.

This paper describes the localization of newly identified visual pigment opsins in the tiered retina of the Japanese yellow swallowtail Papilio xuthus. We first cloned three cDNAs encoding visual pigment opsins, PxRh1, PxRh2 and PxRh3, and then carried out histological in situ hybridization to localize their mRNAs in the retina. By combining the present data with our previous electrophysiological results, we concluded that both PxRh1 and PxRh2 correspond to visual pigments expressed in photoreceptor cells sensitive in the green wavelength region (green receptors), whereas PxRh3 corresponds to a pigment in red receptors. The in situ hybridization studies showed that some photoreceptor cells express two opsin mRNAs. In the ventral half of the eye, all green receptors in the distal tier were labelled by both PxRh1 and PxRh2 probes. The labelling by the PxRh2 and PxRh3 probes was detected throughout the eye in the proximal tier; in 18 % of ommatidia, the probes labelled the same photoreceptor cell. These results suggest that the possible co-localization of two different visual pigments will broaden the sensitivity spectrum of the photoreceptor cells.

Amino Acid Sequence↗
PubMed1998

Alteration in levels of unsaturated fatty acids in mutants of Escherichia coli defective in DNA replication.

We previously reported that mutations in the dnaA gene which encodes the initiator of chromosomal DNA replication in Escherichia coli caused an alteration in the levels of unsaturated fatty acids of phospholipids in membranes. In this study, we examined fatty acid compositions in other mutants which are defective in DNA replication. As in the case of temperature-sensitive dnaA mutants, temperature-sensitive dnaC and dnaE mutants, which have defects in initiation and elongation, respectively, of DNA replication showed a lower level of unsaturation of fatty acids (ratio of unsaturated to saturated fatty acids) compared with the wild-type strain, especially at high temperatures. On the other hand, temperature-sensitive mutants defective in cellular processes other than DNA replication, such as RNA synthesis and cell division, did not show a lower level of unsaturation of fatty acids compared with the wild-type strain. These results suggest that the inhibition of DNA replication causes a lower level of unsaturation of fatty acids in Escherichia coli cells.

Bacterial Proteins↗
PubMed1998

Nonpeptide arginine vasopressin antagonists for both V1A and V2 receptors: synthesis and pharmacological properties of 2-phenyl-4'-(2,3,4,5-tetrahydro-1H-1,5-benzodiazepine-1-carbonyl) benzanilide derivatives.

A series of compounds structurally related to 2-phenyl-4'-(2,3,4,5-tetrahydro-1H-1,5-benzodiazepine-1-carbonyl) benzanilide was synthesized and demonstrated to have arginine vasopressin (AVP) antagonist activity for both V1A and V2 receptors. The introduction of a hydrophilic substituent group into the 5-position of the benzodiazepine ring resulted in an increase in oral availability. Especially, the (3-pyridyl)methyl (31b), the 2-(4-methyl-1,4-diazepan-1-yl)-2-oxoethyl (32i), and the 2-(4-methylpiperazin-1-yl)ethyl (33g) derivatives exhibited high antagonist activities and high oral availability. Details of the synthesis and pharmacological properties of this series are presented.

Anilides↗
PubMed1998

New apparatus stimulating the region of tongue innervated by glossopharyngeal nerve and its application to monosodium glutamate (MSG) solution.

Some apparatuses stimulating the region of tongue innervated by chorda tympani nerve were well known and they were used popularly, but the apparatuses for glossopharyngeal nerve were not produced yet. In the study, the apparatus for the stimulations of glossopharyngeal nerve was trially produced. It was known that the substance of "Umami" was responded well in the tongue region innervated by glossopharyngeal nerve. The evoked potential for the stimulations of monosodium glutamate (MSG) solution which was known as substance of Umami was measured with the use of the trial stimulating apparatus. The evoked potential was detected by monopolar lead for the positions between Cz and A1 (left lobe) with the ground at Fpz. The evoked potential of MSG consisted of a positive peak wave with the latency at approximately 250 ms. The amplitudes increased and the latency decreased as the concentration of MSG increased. The evoked potential stimulating the tongue innervated by this glossopharyngeal nerve could be detected for the first time by the use of the trial apparatus.

Evoked Potentials↗
PubMed1998

Influence of sweet suppressing agent on gustatory brain evoked potentials generated by taste stimuli.

A measurement system was employed to detect gustatory evoked potentials from human scalp by stimulus of a taste solution with the use of a laser beam device. The evoked potentials for four taste qualities (i.e., sweet-sucrose, salty-sodium chloride, sour-tartaric acid, and bitter-quinine-HCl) were measured before and after treatment with a sweet suppressing agent (i.e., gymnema sylvestre extract) to the tongue of a human. The solution was given to the chorda tympani nerve located 20 mm from the apex of the tongue and 15 mm from the left side of the center line. The maximum potential level and its latency were evaluated. Artificial saliva was used as a control solution. The evoked potentials obtained were averaged by eight evoked potentials to detect the peak of the evoked potential more clearly. The latencies for taste stimuli were found on two kinds of peaks at approximately 50 ms and 180 ms. These peaks are P1 and P2. The purpose of this study is to investigate the influence of sweet suppressing agent on P1 and P2. The influence of the sweet suppressing agent to evoked potential by salty, sour, and bitter taste stimuli was not recognized, but the responses to sweet (sucrose) were abolished after treatment with a sweet suppressing agent. It was recognized that the peak P2 originated from the taste stimulus. The peak P1 did not suffer the influence of the sweet suppression, so it was considered that the response to P1 was due to sensations other than the gustatory response, such as somatosense.

Adult↗
PubMed1998

Double infection with Giardia lamblia and Salmonella paratyphi A associated with acute renal failure.

While traveling in India, a previously healthy twenty-year-old man had febrile diarrhea. The patient was prescribed medical therapy, and all symptoms were resolved. Fourteen days later, however, similar symptoms recurred. The patient was admitted to a local hospital, but was transferred to our department because of oliguria. Salmonella paratyphi A was isolated from blood and stool specimens, and Giardia lamblia was identified in his stool. The patient's condition was complicated by acute renal failure. The patient received tosufloxacin and metronidazole. Renal function recovered completely without hemodialysis. Paratyphoid fever and giardiasis were resolved. It is suggested that giardiasis exacerbated the paratyphoid fever.

Acute Kidney Injury↗
PubMed1998

Mechanism of impaired left ventricular wall motion in the diabetic heart without coronary artery disease.

OBJECTIVE: To elucidate whether impairment of the myocardial free fatty acid (FFA) metabolism and small vessel abnormalities in the myocardium are etiologic or contributory factors of myocardial dysfunction in patients with NIDDM without any significant coronary artery disease. RESEARCH DESIGN AND METHODS: We performed myocardial imaging with 123I-labeled beta-methyl-p-iodophenyl pentadecanoic acid (BMIPP), a branched analog of FFA, and dipyridamole-infusion 201thallium scintigraphy (Dip) in nine patients who demonstrated left ventricular wall motion abnormalities without any significant coronary artery disease and in fifteen control cases. As an index of myocardial FFA metabolism, the heart-to-mediastinum count ratio (H/M) of BMIPP was calculated from the mean count in the regions of interest at the heart and the upper mediastinum. RESULTS: Nine patients with reduced wall motion documented by left ventriculography (LVG), (hypokinetic group) demonstrated significantly lower BMIPP uptake (2.1 +/- 0.2, mean +/- SD) than fifteen patients with normal wall motion (normokinetic group) (2.3 +/- 0.2, P < 0.05). Regional ventricular wall motion observed by LVG, regional BMIPP uptake, and regional redistribution phenomenon (RD) were evaluated for five regions of the left ventricle: anterior, septal, apical, lateral, and inferoposterior regions. Wall motion was abnormal in 24 out of 120 regions. Regional BMIPP uptake was reduced in 47 regions. RD in Dip was observed in 23 regions. In regional analysis, the existence of defect in the BMIPP image showed significant correlation with wall motion abnormality (P < 0.01), but there was no significant relationship between the RD in Dip and regional wall motion abnormality (P = 0.16). Myocardial biopsy specimens obtained from the right ventricle of 20 patients showed no pathologic changes, with the exception of two patients. CONCLUSIONS: Our findings suggest that impairment of myocardial FFA metabolism rather than small vessel abnormalities in the myocardium is responsible for modest left ventricular dysfunction in patients with diabetes.

Adult↗
PubMed1998

Effect of captopril on the time-dependent variation of kaolin-induced writhing reaction.

Effect of captopril, an angiotensin-converting enzyme (ACE) inhibitor, on the time-dependent variation of kaolin-induced writhing reactions was examined in mice kept under conditions of light from 07:00 to 19:00 and dark from 19:00 to 07:00. The number of writhes was counted for 60 minutes after a single intraperitoneal injection of kaolin at 01:00, 07:00, 13:00, and 19:00. The number of writhes showed a time-dependent variation, with a peak at 19:00 and a trough at 07:00 in the control group. Captopril significantly increased the number of writhes after dosing at 01:00 and 07:00 (during the active period). The ACE activity following captopril dosing was significantly lower in the 07:00 than the 19:00 trial. These results suggest that the pharmacological effect of captopril varies with the dosing time, and the enhancement of the kaolin-induced writhing reaction is greater following dosing of the agent at nighttime in mice.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

[Significance of accumulation of arteriosclerotic risk factors in elderly people: from a study conducted in Tanno-Sobetsz].

Data from an 18-year prospective study were used to investigate the effect of accumulation of arteriosclerotic risk factors in elderly people on cerebrovascular and cardiovascular disease mortality rates. Risk factors include smoking, hypertension, diabetes mellitus, hyperlipidemia, and obesity. We compared survival rates between a group with few risk factors (< two risk factors) and a group with many risk factors (> or = two risk factors) in four groups of subjects: middle-aged men (< 61-years-old) and middle-aged women and elderly men (> or = 61-years-old) and elderly women. In the elderly male group, the survival rate was lower in subjects with many risk factors than in those with few risk factors. In the middle-aged male group, however, there was no difference between the two risk groups. On the other hand, in the middle-aged female group, the survival rate was lower in subjects with many risk factors than in those with few risk factors, while no difference was found between the two risk groups in the elderly female group. The results indicated that the effects of an accumulation of risk factors are different in men and women and greater in elderly men than in elderly women.

Adult↗
PubMed1998

Molecular cloning of the chick Nau gene and analysis of its expression patterns during neurogenesis.

We have previously identified a novel gene, Nau (Neuron-specific gene, which has a number of AU-rich RNA instability motifs), from a quail spinal cord cDNA library. Nau expression was observed mainly in post-mitotic neuroblasts, especially in the stage of axonogenesis. In this study, we cloned its chick orthologue (cNau, 5069 bp), which encodes 369 amino acid residues. cNau's open reading frame has three highly conserved regions with rat STOP (stable tubule-only polypeptide). cNau may be an orthologue of STOP gene considering its uniqueness in zoo blot analysis and its sequence similarity. Both the genetic structure and temporo-spatial expression patterns indicate that the cNau gene may be related to axonogenesis. In the hindbrain, cNau mRNA was accumulated in rhombomere boundary regions and in the rhombomere 2, 4 and 6. These observations suggest a specific role of cNau in the hindbrain or the difference in development between the hindbrain and spinal cord.

Amino Acid Sequence↗
PubMed1998

Analysis of interaction of spinal and supraspinal reflex pathways involved in physiological tremor.

A model of feedback type in which physiological tremor are produced by both muscular skeletal system and reflex action is described. Analysis of this model shows that the interaction between the spinal and the supraspinal reflex pathways is important in responsible for low and high frequency oscillations of physiological tremor. Particularly the effect of gain ratio of the two pathways is studied in order to examine the role for the two reflex pathways in controlling neuromuscular oscillations. The existence of a critical point of the gain ratio at which one oscillating frequency transitions to two ones is predicted theoretically. A shift of the critical point with variations of weight load is found and suggests a changeable correlation relation between the spinal and the supraspinal pathways due to loading conditions. Our computations for physiological tremor demonstrate the results that the high frequency component of about 25 Hz is produced by the muscle-spinal reflex loop, and the low frequency component of about 10 Hz originates from the central nervous system or from supraspinal reflex loop. Several relations derived in this study are described, and they can be compared with experimental observations. Our model sheds considerable light on the details of the possible mechanism for physiological tremor. In addition, a possibility arising from our study is that the tremulous oscillation associated with some pathological states, say Parkinson's disease, may arise from modified gains in one or more of the reflex pathways.

Humans↗
PubMed1998

[Color Doppler signal enhancement with SH/TH-508 in pancreatic tumors].

In this report, we showed the efficacy of a new contrast agent (SH/TA-508, Schering AG, Germany) for color Doppler imaging of the pancreatic tumors. In pancreatic ductal cancer, no enhancement of the lesion was observed, but vascular invasion by cancer became to be easily evaluated. On the other hand, hypervascular tumors such as islet cell tumor and cystadenocarcinoma, were increased in color Doppler signals of vessels by SH/TA-508. We concluded that SH/TA-508 was useful for evaluating the vascular invasion by pancreatic cancer as well as vascularity of hypervascular mass and solid component of cystic neoplasma.

Adenoma, Islet Cell↗
PubMed1998

[Spinal cord stimulation therapy at an early stage for unresponsive patients with hypoxic encephalopathy].

Recently, spinal cord stimulation (SCS) has been used for the treatment of patients in prolonged coma. However, the results of SCS in unresponsive patients with hypoxic encephalopathy at the chronic stage have not been satisfactory. Considering these circumstances, we began SCS from one month after the onset of hypoxic encephalopathy and evaluated its effect. Twelve patients (5 males and 7 females) with hypoxic encephalopathy, ranging in age from 7 to 72 years, were treated with SCS. The causes of hypoxia were acute cardiac failure in 4, automobile exhaust gas poisoning in 2, and asthma, pneumothorax, anaphylaxis, asphyxia, drowning and hypotension during aortic surgery in one patient each. One month after the onset, an electrode for electrical stimulation was implanted in the epidural space at the C2-C4 level under general anesthesia. The spinal cord was stimulated for 8 hours each day, starting on the day after implantation, and was continued for 3 months. Magnetic resonance imaging (MRI), cerebral blood flow (CBF) measurement using xenon-computed tomography (Xe-CT), and measurement of auditory evoked potential (AEP) and somatosensory evoked potential (SEP) were carried out 3 weeks after the onset for presurgical evaluation. Among the 12 patients, 7 (58%) showed clinical improvement, beginning within two weeks after starting stimulation. They were able to communicate with others and to express their emotion. However, disturbance of writing, picture drawing and calculation were not improved by stimulation. From presurgical evaluation, cases in which SCS therapy was effective had the following features: 1) No hemorrhagic infarction in the basal ganglia was demonstrable by MRI. 2) Mean hemispheric CBF measured by the Xe-CT method exceeded 25 ml/100 g per min. 3) The mean increase in hemispheric CBF 20 min after acetazolamide administration exceeded 5 ml/100 g per min. 4) An N20 peak was evident on the median nerve SEP, SCS appears to be an effective supplementary for unresponsive patients with hypoxic encephalopathy at the subacute stage, in addition to rehabilitation and drug therapy.

Adolescent↗
PubMed1998

Immunohistochemical study of human advanced glycation end-products (AGE) and growth factors in cardiac tissues of patients on maintenance dialysis and with kidney transplantation.

Cardiovascular disease is one of the most common complications of dialysis and renal transplant patients, and high levels of AGE are present in end-stage renal failure. To address the potential involvement of AGE and growth factors in the pathophysiology of cardiovascular complications, we performed immunostaining using cardiac tissues from autopsy cases of patients on maintenance dialysis (10 cases), long-term surviving renal transplant patients with functioning grafts (8 cases), control subjects with normal renal function (7 cases) and non diabetic subjects with mild renal insufficiency (8 cases). We used two types of AGE-antibodies, 6D12 [monoclonal anti-AGE antibody, recognizing N epsilon-(carboxymethyl) lysine(CML)-modified AGE] (oxidative AGE) and non-CML-PA [polyclonal, not recognizing CML], and antibodies against PDGFs, PDGF receptors and TGF beta. Positive 6D12 staining was observed in the coronary arterial walls and in macrophages. The accumulation of 6D12-reactive AGE in the coronary arterial walls of maintenance dialysis patients was significantly greater than that of control subjects (p < 0.05). Renal transplantation significantly reduced this accumulation (p < 0.05). On the other hand non-CML-PA mainly detected AGE in intracardiac arterioles and neural tissues. There was little difference in the accumulation of non-CML-AGE among the four groups. PDGFs and PDGF receptors were mainly detected in vascular endothelial cells and infiltrating cells of cardiac tissues of renal transplant patients, but not of maintenance dialysis patients. TGF beta was not detected in cardiovascular tissue of transplant patients. Our results indicated that the accumulation of oxidative AGE (CML-AGE) in the cardiac vascular tissue is one of the factors for cardiovascular complications of maintenance dialysis patients, and also that renal transplantation has a reducing effect on CML-AGE accumulation. PDGFs may be involved in the cardiovascular complications after renal transplantation.

Adult↗
PubMed1998

[Evaluation of patients with cerebral infarction using transesophageal echocardiography: atherosclerotic changes in the thoracic aorta and the branches of the aortic arch].

Atherosclerotic disease of the aortic arch is thought to be a potential source of cerebral emboli, but this disease in the branch of the aortic arch has not been extensively explored. This study assessed atherosclerotic lesions in the thoracic aorta and the branches of the aortic arch using transesophageal echocardiography in patients with cerebral infarction, and simultaneously searched for potential cardiac sources for emboli. Thrombi were detected in the left atrial appendage in nine of 54 patients with cerebral infarction and these patients were excluded. The remaining 45 patients with cerebral infarction (31 males and 14 females aged 68.5 +/- 7.4 years) and 35 normal subjects (21 males and 14 females aged 69.2 +/- 9.5 years) were evaluated. The thickness of the wall was measured in the branches of the aortic arch (brachiocephalic trunk, left common carotid artery and left subclavian artery) as well as the thoracic aorta (ascending aorta, aortic arch and descending aorta). Atherosclerotic lesions were defined as increased echogenicity of the intima (intimal thickening), calcification, protruded plaque, ulceration or plaque with cystic lesion. The thicknesses of the wall in the aortic arch (3.84 +/- 1.25 vs 2.71 +/- 1.33 mm, p < 0.01), left common carotid artery (2.67 +/- 1.10 vs 2.16 +/- 0.91 mm, p < 0.05) and the left subclavian artery (2.52 +/- 0.67 vs 2.15 +/- 0.88 mm, p < 0.05) were significantly greater in patients than in the normal subjects. The incidence of plaque or ulceration was significantly increased in patients with cerebral infarction compared with the normal subjects in the aortic arch (76% vs 43%, p < 0.05) and left common carotid artery (44% vs 17%, p < 0.05). Transesophageal echocardiography can detect possible sources of emboli in the branches of the aortic arch as well as the thoracic arch in patients with cerebral infarction.

Aged↗
PubMed1998

[Thymic anaplastic carcinoma successfully controlled by combination chemotherapy].

Thymic carcinomas are rare tumors for which the main treatments have been surgery, radiotherapy, or both. However, the role of chemotherapy is less well-defined. Here, we report a case of advanced thymic anaplastic carcinoma which was suspected to be the primary lesion, yet was successfully controlled despite brain metastases by EACUM combination chemotherapy consisting of cyclophosphamide, adriamycin, cisplatin, 5-FU, and methtrexate. Pathohistological findings on metastatic lesions of the right supracuravicular lymph nodes led to a diagnosis of anaplastic carcinoma. We could not give a diagnosis of thymic carcinoma because the biopsy specimen had not been taken from the thymus. There was no evidence of a primary neoplastic tumor other than thymoma. The patient was still alive 6 years and 9 months after the start of anticancer treatment and was working normally. The findings from this case should be of value to the establishment of effective combination chemotherapy regimens for advanced thymic carcinoma.

Adult↗
PubMed1998

Mineral concentrations in the blood of male smokers and non-smoking males and females measured with fluoro-X-ray analyzer.

For clarification of the effects of smoking on mineral absorption in red blood cells (RBC) and serum, their concentrations at these sites were examined in ten male smokers and 12 male and 10 female non-smokers by fluoro-X-ray analysis. K in serum was high, and P, Ca and Fe low, compared to RBC. Mg and S in serum and RBC were essentially the same. S, Mg, P and K in RBC of smokers were higher than in male non-smokers, and Ca was lower. S and Ca in serum of smokers were significantly lower than in male non-smokers. P in smokers was higher than in non-smokers. P in RBC may possibly activate the reflux of Mg into RBC and may suppress that of Ca. In smokers, the correlation coefficient (gamma) between Fe and Ca was r = -0.68 in RBC, and r = 0.76 in serum. Also gamma between P and Mg was r = 0.4 in RBC and r = -0.48 in serum. Thus Fe in RBC may suppress the reflux of Ca. Mg and Ca in serum of females were significantly higher than in male non-smokers. Ca in RBC of females was significantly higher than in male non-smokers, and P, K and Fe were significantly lower. The product of Ca and P in RBC of females was lower than in male non-smokers, while in serum it was higher. gamma between P and Ca, and between Fe and Ca in RBC of females were negative, while they were positive in male non-smokers. The correlations in female RBC had the same pattern as in male smokers.

Adult↗