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Biomedical subjects

S Yamaguchi

Publications and source records attributed to S Yamaguchi.

At least 397 records · Page 22Linked to original sources
PubMed1998

Stability of the C-terminal alpha-helical domain of bacteriorhodopsin that protrudes from the membrane surface, as studied by high-resolution solid-state 13C NMR.

We have recorded 13C NMR spectra of [1-(13)C]Ala- and [3-(13)C]Ala-bacteriorhodopsin (bR), [1-(13)C]Ala- and [3-(13)C]Ala-papain-cleaved bR, and [3-(13)C]Ala-labeled R227Q bR mutant by cross polarization-magic angle spinning (CP-MAS) and dipolar decoupled-magic angle spinning (DD-MAS) methods. The pH and temperature were varied, and Arg 227 was replaced with Gln (R227Q), in order to clarify their effects on the stability of the alpha-helical domain of the C-terminus that protrudes from the membrane surface. The comparative 13C CP- and DD-MAS NMR study of [3-(13)C]Ala-bR, rather than [1-(13)C]Ala-bR, turned out to be the best means to distinguish the 13C NMR signals of the C-terminus from those of the rest of the transmembrane helices or loops. The inner segment of the C-terminus, from Ala 228 to Ala 235, forms an alpha-helical domain (resonated at 15.9 ppm) either at neutral pH and/or at 10 to -10 degrees C. The alpha-helical peak was not seen, however, after either cleavage of the C-terminus with papain or lowering the pH to 4.25. This alpha-helical structure, and a part of the random coil which was produced from the helix at pH 4.25, were further converted to a low-temperature-type alpha-helix, as indicated by an upfield displacement of the 13C NMR signal, when the temperature was lowered to 10- -10 degrees C. Surprisingly, the corresponding helical structure in R227Q is more stable than in the wild type at the acidic pH. This alpha-helical peak was classified as an alphaII-helix from the 13C chemical shifts of Cbeta carbon, although it was ascribed to an alphaI-helix on the basis of the carbonyl shifts. This is in contrast to Ala 53 which adopts the alphaII-helix as judged from the 13C chemical shifts of Cbeta and the carbonyl carbons. Therefore, this discrepancy might be caused by differential sensitivity of the two types of carbon signals to conformation and to modes of hydrogen bonding when motional fluctuation is involved. It is likely that the alphaII-helix form present at the C-terminus is not always the type originally proposed but should be considered as a form undergoing large-amplitude conformational fluctuation around alpha-helix.

Amino Acid Sequence↗
PubMed1998

Association between carotid atherosclerosis and hemostatic markers in patients with cerebral small artery disease.

The purposes of this study were to investigate the association between carotid atherosclerosis and hemostatic markers, and to elucidate the difference in hemostatic markers between intima-media thickening and plaque formation in patients with cerebral small artery disease. We investigated carotid atherosclerosis by assessing diffuse intima-media thickness measurements and localized plaque using B-mode ultrasonography, and we measured the concentrations of plasma fibrinogen, beta-thromboglobulin and platelet factor 4 as markers for platelet activation, and the activity of plasma von Willebrand factor as a marker for endothelial damage. The intima-media thickness was significantly associated with age, male sex, the concentrations of plasma beta-thromboglobulin and platelet factor 4, and the activity of plasma von Willebrand factor. The plaque score showed a significant association with male sex, the concentration of fibrinogen, and the activity of plasma von Willebrand factor. These results may indicate that underlying mechanisms are not the same between the intima-media thickness and plaque formation. We suggest that hemostatic markers could reflect the severity of carotid atherosclerosis in patients with cerebral small artery disease, and that preventive antiplatelet therapies against brain infarction might be necessary for patients with severe carotid atherosclerosis.

Adult↗
PubMed1998

The GA2 locus of Arabidopsis thaliana encodes ent-kaurene synthase of gibberellin biosynthesis.

The ga2 mutant of Arabidopsis thaliana is a gibberellin-deficient dwarf. Previous biochemical studies have suggested that the ga2 mutant is impaired in the conversion of copalyl diphosphate to ent-kaurene, which is catalyzed by ent-kaurene synthase (KS). Overexpression of the previously isolated KS cDNA from pumpkin (Cucurbita maxima) (CmKS) in the ga2 mutant was able to complement the mutant phenotype. A genomic clone coding for KS, AtKS, was isolated from A. thaliana using CmKS cDNA as a heterologous probe. The corresponding A. thaliana cDNA was isolated and expressed in Escherichia coli as a fusion protein. The fusion protein showed enzymatic activity that converted [3H]copalyl diphosphate to [3H]ent-kaurene. The recombinant AtKS protein derived from the ga2-1 mutant is truncated by 14 kD at the C-terminal end and does not contain significant KS activity in vitro. Sequence analysis revealed that a C-2099 to T base substitution, which converts Gln-678 codon to a stop codon, is present in the AtKS cDNA from the ga2-1 mutant. Taken together, our results show that the GA2 locus encodes KS.

Alkyl and Aryl Transferases↗
PubMed1998

The first step of gibberellin biosynthesis in pumpkin is catalyzed by at least two copalyl diphosphate synthases encoded by differentially regulated genes.

The first step in gibberellin biosynthesis is catalyzed by copalyl diphosphate synthase (CPS) and ent-kaurene synthase. We have cloned from pumpkin (Cucurbita maxima L.) two cDNAs, CmCPS1 and CmCPS2, that each encode a CPS. Both recombinant fusion CmCPS proteins were active in vitro. CPS are translocated into plastids and processed by cleavage of transit peptides. For CmCPS1 and CmCPS2, the putative transit peptides cannot exceed the first 99 and 107 amino acids, respectively, because longer N-terminal deletions abolished activity. Levels of both CmCPS transcripts were strictly regulated in an organ-specific and developmental manner. Both transcripts were almost undetectable in leaves and were abundant in petioles. CmCPS1 transcript levels were high in young cotyledons and low in roots. In contrast, CmCPS2 transcripts were undetectable in cotyledons but present at significant levels in roots. In hypocotyls, apices, and petioles, CmCPS1 transcript levels decreased with age much more rapidly than those of CmCPS2. We speculate that CmCPS1 expression is correlated with the early stages of organ development, whereas CmCPS2 expression is correlated with subsequent growth. In contrast, C. maxima ent-kaurene synthase transcripts were detected in every organ at almost constant levels. Thus, ent-kaurene biosynthesis may be regulated through control of CPS expression.

Alkyl and Aryl Transferases↗
PubMed1998

Phytochrome regulation and differential expression of gibberellin 3beta-hydroxylase genes in germinating Arabidopsis seeds.

Despite extensive studies on the roles of phytochrome in photostimulated seed germination, the mechanisms downstream of the photoreceptor that promote germination are largely unknown. Previous studies have indicated that light-induced germination of Arabidopsis seeds is mediated by the hormone gibberellin (GA). Using RNA gel blot analyses, we studied the regulation of two Arabidopsis genes, GA4 and GA4H (for GA4 homolog), both of which encode GA 3beta-hydroxylases that catalyze the final biosynthetic step to produce bioactive GAs. The newly isolated GA4H gene was expressed predominantly during seed germination. We show that expression of both GA4 and GA4H genes in imbibed seeds was induced within 1 hr after a brief red (R) light treatment. In the phytochrome B-deficient phyB-1 mutant, GA4H expression was not induced by R light, but GA4 expression still was, indicating that R light-induced GA4 and GA4H expression is mediated by different phytochromes. In contrast to the GA4 gene, the GA4H gene was not regulated by the feedback inhibition mechanism in germinating seeds. Our data demonstrate that expression of GA 3beta-hydroxylase genes is elevated by R light, which may result in an increase in biosynthesis of active GAs to promote seed germination. Furthermore, our results suggest that each GA 3beta-hydroxylase gene plays a unique physiological role during light-induced seed germination.

Amino Acid Sequence↗
PubMed1998

Coronary risk factors in acute Kawasaki disease: correlation of serum immunoglobulin levels with coronary complications.

BACKGROUND: To determine the usefulness of the IgG z-score (age and sex-standardized serum IgG level) before intravenous gamma globulin therapy (IVGG) in predicting the occurrence or severity of coronary complications in Kawasaki disease (KD). METHODS: A case-control study of clinical and laboratory findings with 88 children in the early stage of acute KD who received IVGG (100 or 200 mg/kg for 2-5 days) therapy. Of these, 20 cases had persistent coronary arterial lesions (small aneurysm, moderate aneurysm or large aneurysm persisting more than 1 month). The controls comprised 68 children with no coronary aneurysms or transient small aneurysm only observed within 1 month after the onset of KD. The association between serum levels of immunoglobulin G (IgG). IgM, IgA as well as other coronary risk factors previously reported and the occurrence of the coronary arterial lesions was evaluated using logistic regression analysis. RESULTS: After adjustment for age, gender, total IVGG dose before the 9th illness day and other traditional coronary risk factors, the odds ratio for the persistent coronary aneurysm associated with lower serum IgG z-score (< -0.7485 vs > or = -0.7485), was 30.3 (95% confidence interval, 3.8-243.2). Furthermore, the serum IgG z-score was inversely correlated with the severity of the coronary arterial lesion. CONCLUSIONS: The IgG z-score before IVGG therapy in the early stage of KD provides useful information on the risk factors for persistent coronary aneurysm and is a novel, additional indicator for therapy to prevent the coronary complications in acute KD.

Case-Control Studies↗
PubMed1998

An evaluation of infants' growth in the Kingdom of Nepal.

BACKGROUND: The His Majesty's Government/Japan International Cooperation Agency Primary Health Care Project began in April 1993 in collaboration with the Saitama Prefectural Government, for the purpose of improving the health status of the people in model districts of the Kingdom of Nepal. Growth monitoring is one of the basic methods that defines the health and nutritional status of children. METHODS: Anthropometric indices were measured in 759 children in the Bhaktapur district. We used the World Health Organization prototype growth chart and national growth standard for Japanese children (1990) to analyze the growth data. RESULTS: We found that the average bodyweight growth curve of children up to 4 months of age followed the 50th percentile reference curve. For children of 5-12 months of age, there was a delay in bodyweight gain and the growth curve reached the 3rd percentile curve. For children more than 1 year old, the growth curve moved below the third percentile curve. Catch-up growth did not occur before the children reached 5 years of age. The main causes of catch-up growth being hampered were chronic undernutrition and inadequate nutritional balance. CONCLUSIONS: As this was the first opportunity to evaluate infant growth in this district, the first important consequence of the results was to analyze the causes of growth faltering and failure-to-thrive in Nepalese children. Even more important, was the need to give appropriate counseling on improving feeding and other health-related practices, and the most important consequence of all was to instruct Nepalese health workers that utilizing the growth charts is an integral part of health care.

Anthropometry↗
PubMed1998

Kanji-predominant alexia in advanced Alzheimer's disease.

OBJECTIVES: Oral reading is preserved until the late stage of Alzheimer's disease (AD). However, it is unknown whether reading of kanji and kana is differentially impaired in Japanese AD patients. The purpose of this study was to examine alexic pattern in AD as related to two script systems. MATERIAL AND METHODS: In 18 severe AD patients, reading performance was compared among kana characters, monographic kanji words, and kana-transcribed words. Auditory comprehension was also examined. RESULTS: With increased severity of dementia, kanji reading was clearly more impaired than kana reading, which was relatively unaffected. Graphic complexity and frequency of the kanji influenced the performance variously among the patients. Dissociation between kanji reading and comprehension was also noted. CONCLUSION: As a result of multiple cognitive deficits, kanji reading is more impaired than kana reading in AD, but the difference is apparent only in the very late stage. Our findings suggest that kanji can be read correctly without meaning.

Adult↗
PubMed1998

Visuospatial attention shift and motor responses in cerebellar disorders.

The cerebellum has been implicated in higher cognitive functions including learning, memory, and attention as well as its well-known role in motor programming. Recent studies have suggested that the cerebellum plays a role in shifts of attention. We investigated the contribution of the cerebellum to visuospatial attentional ability in a trial-by-trial cueing task involving the covert orienting of spatial attention. We recorded event-related evoked potentials (ERPs) and reaction times (RTs) in patients with cerebellar degenerative disorders affecting mainly the lateral cerebellum and compared them to age-matched controls. The RT data demonstrated that both the cerebellar patients and control subjects responded to the valid cues faster than to the invalid cues for both the central and the peripheral cues. Consistent with the RT data, the ERP data showed a comparable generation of attention shift-related negativities during the cue-target interval for both the central and the peripheral cue experiments. The early negative component of the ERP to the target was also comparably modulated in both groups as a function of cue validity, suggesting efficient facilitation of sensory pathways by prior allocation of spatial attention to the cued place. Conversely, the late negative deflection preceding the imperative target stimulus and the late sustained positivity following target presentation, which reflect neural activities for response preparation and selection, were reduced in the cerebellar group. These findings suggest that the lateral cerebellum makes little contribution to visuospatial attention shift in either the voluntary or automatic modes and support a role of the lateral cerebellum in the neural system required for response preparation and selection.

Adult↗
PubMed1998

Bile acids of Fel Ursi.

The first direct separation of Fel Ursi using octadecyl silica (ODS) open column chromatography has been accomplished and provided to provide several pure, free and conjugated bile acids, the structures of which were substantiated by spectroscopic methods.

Animals↗
PubMed1998

[A method of measuring eruptive movement of the rat incisor using a non-contacting displacement detector].

The axial movements of rat incisors were recorded continuously for over 20 hr. The rats were anesthetized with halothane delivered by intratracheal intubation using an artificial respirator. A hemostatic clamp was used to immobilize the jaw. The displacement detector that detects changes in the electric eddy current exhibited high resolution, good linearity and low drift. The average eruption rates of the rat incisor were estimated to be 406 and 516 microns/ 24 hr at 34 and 37 degrees C of the rectal temperature, respectively. The values were within the normal range. We also measured the force needed to restrain eruptive movement of the rat incisor using the same apparatus combined with a load cell. The maximum pushing force was estimated to be 9 mN or 29 mmHg (converted value) on average. Then the effects of adrenaline on axial movement of the incisor and arterial blood pressure were examined. Adrenaline caused a rapid extrusive tooth movement with a nearly simultaneous increase in the blood pressure, followed by a marked intrusive tooth movement and a decrease in blood pressure. These results support the view that the systemic arterial blood pressure and vasculature in the tooth socket play important roles to determine the position of teeth. We assume that our method would be useful to clarify the precise relationship between tooth displacement and vascular change in the tooth socket.

Alveolar Process↗
PubMed1998

Developmental changes in expression of angiotensinogen mRNA in rat nephron segments.

We studied the localization of angiotensinogen mRNA in rat nephron segments and the differences in angiotensinogen mRNA levels between male Sprague-Dawley rats at 6 and 12 wk of age using reverse transcription and polymerase chain reaction (RT-PCR). Each nephron segment of the rat kidney was microdissected. Total RNA was prepared and used in the following RT-PCR assay. The PCR products were size-fractionated by agarose gel electrophoresis, visualized with ethidium bromide staining, and identified by Southern blot analysis. The relative amounts of products were determined by densitometry. Strong bands corresponding to angiotensinogen mRNA were detected from proximal convoluted and straight tubules, and weaker bands were found in glomeruli. The signals in all tissues in 12-wk-old rats were weaker than those in 6-wk-old rats. Since local angiotensinogen is the unique substrate of the tissue renin-angiotensin system and exerts an autocrine-paracrine influence on renal function, the changes in tubular angiotensinogen may be related to physiological and morphological changes in the rat kidney during development.

Angiotensinogen↗
PubMed1998

Hemagglutination with crane herpesvirus.

A crane herpesvirus (CrHV) grown in chicken embryo fibroblast (CEF) cells was tested for hemagglutination (HA) with erythrocytes from a variety of species at 4 degrees C, room temperature and 37 degrees C. HA was observed at all temperatures with erythrocytes from mouse, ddY and BALB/c strains, but not with those from cattle, sheep and chicken. Mice, ddY strain, showed an individual variation in agglutinability of their erythrocytes and erythrocytes from BALB/c gave a higher HA titer. The HA activity was inhibited by the sera obtained from naturally infected cranes, experimentally infected duck and immunized rabbit with CrHV. HI antibody titers of these sera showed a closely positive correlation with their neutralizing antibody titers.

Animals↗
PubMed1998

Practical assay method of cytosolic acetoacetyl-CoA thiolase by rapid release of cytosolic enzymes from cultured lymphocytes using digitonin.

We designed a simple approach to determine cytosolic acetoacetyl-CoA thiolase (CT) activity for differential diagnosis of ketone body catabolic defects, using rapid cell-subfractionation of cultured lymphocytes with digitonin. Efficiency of cell subfractionation was determined by measurement of lactate dehydrogenase and citrate synthetase as marker enzymes for cytosol and organelle fractions, respectively, and confirmed by immunotitration and immunoblotting using antibodies against cytosolic and mitochondrial thiolases, respectively. In the condition of best separation taken in the presence of 1 mg/ml digitonin, acetoacetyl-CoA thiolase activities in the presence of K+ ion in the cytosol and organelle fractions were 138.3+/-39.2 and 84.0+/-16.2 nmol/min/ml, respectively. The thiolase activity in the organelle fraction was doubled by the presence of K+ ion, whereas that in the cytosol fraction was not affected. The thiolase activity in the organelle fraction was reduced by the treatment of anti-mitochondrial acetoacetyl-CoA thiolase (T2) antibody but not by anti-CT antibody. On the other hand, that in the cytosol fraction was significantly decreased by anti-CT antibody but not by anti-T2 antibody. These data suggested that T2 was collected in the organelle fraction, and that CT activity could be assessed by measurement of the thiolase activity in the cytosolic fraction. Succinyl-CoA: 3-ketoacid CoA transferase (SCOT), whose defect is the third inherited disorder of ketone body catabolism, was collected in the organelle fraction. Hence, this method will prove to be useful for accurate assessment of defects of CT as well as T2 or SCOT, all involved in ketone body catabolism.

Acetyl-CoA C-Acetyltransferase↗
PubMed1998

[Association between social environment and aging of the brain: evaluation with the event-related potential P300].

PURPOSE AND METHODS: To investigate the association between social environment and aging of the brain, we studied P300 event-related evoked potentials in 95 normal elderly subjects living in different social environments. The subjects were divided into two groups: 22 healthy people living in old-age homes (average age 76.5 +/- 5.6 years, average Hasegawa Dementia Scale-Revised 27.4 +/- 2.5), and 93 healthy people living in their own homes (average age 74.1 +/- 5.4 years, average Hasegawa Dementia Scale-Revised 28.3 +/- 2.3). Target and Novelty P300 were recorded by using an auditory oddball paradigm. There were no differences in risk factors for strokes or in findings on magnetic resonance imaging between the two groups. RESULTS: Cognitive function (Okabe's Score and Koh's Block Design Test) were lower in those living in an old-age home than in those living in their own homes. Both target and novelty N100 examinations showed no significant differences in amplitude or latencies between the two groups. However, P300 latencies were larger among those living in an old-age home than among those living in their own homes; P300 amplitudes in the two groups were similar. Those living in an old-age home also had greater age-associated declines in function, as shown by longer latencies in target P300 than in novelty P300. CONCLUSION: Social-environmental factors are closely associated with the aging of the brain.

Aged↗
PubMed1998

[A study of the differences between the sexes in epidemiology of urolithiasis].

PURPOSE: Uroithiasis seems to be the dominant disease for male. In the recent Japanese epidemiological report, the sexual ratio was reported 2.3:1. This sexual ratio is almost stable from 1960. We studied epidemiologically based on age and stone components the differences between the sexes. PATIENTS AND METHOD: From 1977 to 1996 the upper urinary tract stones which spontaneous excretion or surgical removal in our hospital were the subjects of study, Stone analysis was carried out infrared spectrometer. The statistical analyses were performed by the chi-square test and Mann-Whitney's U test. Significance was declared for a probability value of less than 0.05. RESULTS: In the epidemiology of our treated patients sexual ratio was 1.83:1. We studied sexual ration in age and stone components. The sexual ratio of the patients, 60 years and over was decreased compared with that of the patients under 60 years of age. We found the tendency that the sexual ratio was decreased at 60 years old and over. In the female urolithiasis patients less than 60 years old the frequency of calcium oxalate contained stone patients was predominantly smaller than male. In the female urolithiasis patients of 60 years and over the stone component ratio was similar to male urolithiasis patients. CONCLUSION: In point of frequency sexual ratio was decreased at 60 years old and over. In the female patients less than 60 years old the frequency of calcium oxalate contained stone was predominantly small. This low frequency of calcium oxalate contained stone in the female less than 60 years old seemed to be a factor of the sex differences of frequency.

Adolescent↗
PubMed1998

[A case of hereditary motor and sensory neuropathy with pyramidal tract sign, optic nerve atrophy and mental retardation].

The patient was a 61-year-old man who suffered from gait disturbance since childhood. He also had mental retardation. Gait disturbance was slowly progressive. His mother, sister, brother and son of his sister suffered from gait disturbance. On neurological examination, he showed mental retardation, optic nerve atrophy and neural deafness. He also showed severe muscle atrophy and weakness of bilateral lower limbs associated with pes cavus. Muscle tonus of lower limbs and patellar tendon reflex were increased bilaterally. Achilles tendon reflex was absent. Babinski and Chaddock signs were positive. Superficial and deep sensations were almost normal. There were no cerebellar signs. Blood chemistry was normal. On nerve conduction studies, motor nerve conduction velocity of the upper limbs was normal and that of the posterior tibial nerve was decreased; right 36.0m/sec, left 29.7m/sec. Sensory nerve conduction velocity of the median nerve was slightly decreased; right 36.5m/sec, left 45.2m/sec and sural nerve did not respond to electric stimuli. On sural nerve biopsy, the density of myelinated fibers was severely decreased. Onion bulb formation was not observed. We classified this case as hereditary motor and sensory neuropathy (HMSN) type II based on nerve conduction studies and findings from sural nerve biopsy. HMSN with pyramidal tract sign has been classified as type V and HMSN with optic nerve atrophy as type VI. This case had characteristic symptoms as type V and VI. Histopathological findings of HMSN type V and VI have not been established yet. This case might provide an important clue for classification of HMSN.

Hereditary Sensory and Motor Neuropathy↗