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Biomedical subjects

T Mitsuhashi

Publications and source records attributed to T Mitsuhashi.

At least 73 records · Page 4Linked to original sources
PubMed1997

Depletion of reactive advanced glycation endproducts from diabetic uremic sera using a lysozyme-linked matrix.

Diabetic uremic sera contain excessive amounts of reactive advanced glycation endproducts (AGEs), which accelerate the vasculopathy of diabetes and end-stage renal disease. To capture in vivo-derived toxic AGEs, high affinity AGE-binding protein lysozyme (LZ) was linked to a Sepharose 4B matrix. Initial studies showed that > 80% of 125I-AGE-BSA was retained by the LZ matrix, compared with < 10% retained by a control matrix. More than 60% of AGE-lysine was captured by the LZ matrix, and the LZ-bound fraction retained immunoreactivity and cross-linking activity, but had little intrinsic fluorescence (370/440 nm). After passage through the LZ matrix, AGE levels in diabetic sera (0.37+/-0.04 U/mg) were significantly reduced to a level (0.09+/-0.01 U/mg; n = 10; P < 0. 0001) comparable with the level of normal human serum, whereas total protein absorption was < 3%. The AGE-enriched serum fraction exhibited cross-linking activity, which was completely prevented by aminoguanidine. Among numerous LZ-bound proteins in diabetic uremic sera, three major proteins "susceptible" to AGE modification were identified: the immunoglobulin G light chain, apolipoprotein J (clusterin/SP-40,40), and the complement 3b beta chain. These findings indicate that the LZ-linked AGE affinity column may serve as an efficient method for the depletion of toxic AGEs from sera, including specific AGE-modified proteins that may be linked to altered immunity, lipoprotein metabolism, and accelerated vasculopathy in renal failure patients with or without diabetes.

Adult↗
PubMed1997

Orally absorbed reactive glycation products (glycotoxins): an environmental risk factor in diabetic nephropathy.

Endogenous advanced glycation endproducts (AGEs) include chemically crosslinking species (glycotoxins) that contribute to the vascular and renal complications of diabetes mellitus (DM). Renal excretion of the catabolic products of endogenous AGEs is impaired in patients with diabetic or nondiabetic kidney disease (KD). The aim of this study was to examine the oral absorption and renal clearance kinetics of food AGEs in DM with KD and whether circulating diet-derived AGEs contain active glycotoxins. Thirty-eight diabetics (DM) with or without KD and five healthy subjects (NL) received a single meal of egg white (56 g protein), cooked with (AGE-diet) or without fructose (100 g) (CL-diet). Serum and urine samples, collected for 48 hr, were monitored for AGE immunoreactivity by ELISA and for AGE-specific crosslinking reactivity, based on complex formation with 125I-labeled fibronectin. The AGE-diet, but not the CL-diet, produced distinct elevations in serum AGE levels in direct proportion to amount ingested (r = 0.8, P < 0.05): the area under the curve for serum ( approximately 10% of ingested AGE) correlated directly with severity of KD; renal excretion of dietary AGE, although normally incomplete (only approximately 30% of amount absorbed), in DM it correlated inversely with degree of albuminuria, and directly with creatinine clearance (r = 0.8, P < 0.05), reduced to <5% in DM with renal failure. Post-AGE-meal serum exhibited increased AGE-crosslinking activity (two times above baseline serum AGE, three times above negative control), which was inhibited by aminoguanidine. In conclusion, (i) the renal excretion of orally absorbed AGEs is markedly suppressed in diabetic nephropathy patients, (ii) daily influx of dietary AGEs includes glycotoxins that may constitute an added chronic risk for renal-vascular injury in DM, and (iii) dietary restriction of AGE food intake may greatly reduce the burden of AGEs in diabetic patients and possibly improve prognosis.

Adolescent↗
PubMed1997

Glycation products in aged thioglycollate medium enhance the elicitation of peritoneal macrophages.

Thioglycollate medium (TGM) is widely used as a stimulatory agent to induce non-infectious peritoneal inflammation for elicitation of macrophages from mice and rats. It has been known for a long time that aged, autoclaved TGM is more efficient than freshly prepared TGM, however, the mechanism responsible for this enhanced activity of aged TGM remains obscure. The aging of TGM apparently favors the non-enzymatic reactions between proteins and reducing sugars in TGM that may lead to the generation of advanced glycation endproducts (AGEs). We have found that aged TGM contains 40-fold more AGEs than fresh TGM. The formation of AGEs in TGM was completely blocked by co-incubation with an AGE inhibitor, aminoguanidine. Intraperitoneal injection of aged TGM into rats elicited approximately 2-fold more macrophages than fresh TGM. However, the addition of AGE-modified proteins to fresh TGM increased the yield of peritoneal cells to a level which was significantly higher than both fresh and aged TGM. The injection of AGE-modified proteins alone did not elicit significantly more macrophages than the level of resident peritoneal cells. These results suggest that the formation of AGEs during aging of TGM is responsible for the enhanced macrophage-eliciting activity in aged TGM. AGEs may act as an enhancing agent to augment the existing inflammatory responses. AGE-supplemented TGM may provide an efficient method for eliciting peritoneal macrophages or establishing an inflammatory animal model.

Animals↗
PubMed1997

Autonomic nervous system dysfunction in elderly hypertensive patients with abnormal diurnal blood pressure variation: relation to silent cerebrovascular disease.

To investigate the relationships among diurnal blood pressure (BP) variations and autonomic nervous system dysfunction, we assessed heart rate variability (HRV) using power spectral analysis of the 24-hour RR interval in 51 asymptomatic elderly hypertensive patients with various patterns of nocturnal BP fall. The extreme-dippers with marked nocturnal BP fall (n=16) had lower asleep low-frequency power (LF)/high-frequency power (HF) ratios (a relative index of sympathetic nervous system activity), while the nondippers without nocturnal BP fall (n=18) had lower awake LF/HF ratios and asleep/awake ratio for HF (an index of parasympathetic nervous activity), when compared with dippers with appropriate nocturnal BP fall (n=17). The incidence of multiple lacunar infarction detected by brain magnetic resonance imaging was 56% in the extreme-dippers and 38% in the nondippers, and both were markedly higher than that (6.3%) in the dippers (both P<.01). There was no significant relationship between the BP level and any HRV parameter for either the daytime or nighttime period. The asleep/awake ratio for systolic BP was significantly correlated with the asleep/awake ratio for HF (r= -.363, P<.01) and with the asleep/awake ratio for the LF/HF ratio (r=.540, P<.001), regardless of whether multiple lacunar infarction was present. In conclusion, the autonomic nervous system activity is not related to high BP level per se, rather its diurnal variation is more important as a determinant of the diurnal BP patterns, regardless of the presence or absence of cerebrovascular disease.

Aged↗
PubMed1996

Molecular identity and cellular distribution of advanced glycation endproduct receptors: relationship of p60 to OST-48 and p90 to 80K-H membrane proteins.

Advanced glycation endproducts (AGEs) are derivatives of nonenzymatic reactions between sugars and protein or lipids, and together with AGE-specific receptors are involved in numerous pathogenic processes associated with aging and hyperglycemia. Two of the known AGE-binding proteins isolated from rat liver membranes, p60 and p90, have been partially sequenced. We now report that the N-terminal sequence of p60 exhibits 95% identity to OST-48, a 48-kDa member of the oligosaccharyltransferase complex found in microsomal membranes, while sequence analysis of p90 revealed 73% and 85% identity to the N-terminal and internal sequences, respectively, of human 80K-H, a 80- to 87-kDa protein substrate for protein kinase C. AGE-ligand and Western analyses of purified oligosaccharyltransferase complex, enriched rough endoplasmic reticulum, smooth endoplasmic reticulum, and plasma membranes from rat liver or RAW 264.7 macrophages yielded a single protein of approximately 50 kDa recognized by both anti-p60 and anti-OST-48 antibodies, and also exhibited AGE-specific binding. Immunoprecipitated OST-48 from rat rough endoplasmic reticulum fractions exhibited both AGE binding and immunoreactivity to an anti-p60 antibody. Immune IgG raised to recombinant OST-48 and 80K-H inhibited binding of AGE-bovine serum albumin to cell membranes in a dose-dependent manner. Immunostaining and flow cytometry demonstrated the surface expression of OST-48 and 80K-H on numerous cell types and tissues, including mononuclear, endothelial, renal, and brain neuronal and glial cells. We conclude that the AGE receptor components p60 and p90 are identical to OST-48, and 80K-H, respectively, and that they together contribute to the processing of AGEs from extra- and intracellular compartments and in the cellular responses associated with these pathogenic substances.

Amino Acid Sequence↗
PubMed1996

Relationship between severity of mitral regurgitation and prognosis of mitral valve prolapse: echocardiographic follow-up study.

We investigated the relation between the severity of mitral regurgitation and the development of complications and cardiac events by using two-dimensional and color Doppler echocardiography in 229 consecutive patients with mitral valve prolapse. The frequency of moderate and severe mitral regurgitation was significantly higher in patients with a prolapsed posterior leaflet (61%) than in patients with a prolapsed anterior leaflet (25%), and the older the patient, the greater the severity of mitral regurgitation. The occurrence of complications, such as atrial fibrillation, congestive heart failure, and chordal rupture, was significantly greater in prolapsed posterior leaflet cases than in prolapsed anterior leaflet cases, and the occurrence was closely associated with the degree of severity of mitral regurgitation. Multiple logistic regression analysis showed that the severity of mitral regurgitation is a strong prognostic indicator for developing complications. Furthermore in a subgroup of 49 patients tracked for a mean of 4.8 years, the new development of complications was significantly higher in patients who showed a progression in the severity of mitral regurgitation (52%) that in patients without progression in severity (8%). The initial severity of mitral regurgitation was related to the occurrence of cardiac events (mitral valve replacement, infective endocarditis, cerebral embolism and death). The data indicated that the progression of mitral regurgitation is closely associated with the development of complications and cardiac events and suggest that the severity of mitral regurgitation is an important prognostic indicator for the development of complications and cardiac events in patients with mitral valve prolapse.

Adolescent↗
PubMed1996

Evaluation of stereoscopic picture quality with CFF.

The method of binocular stereoscopic imaging has attracted attention as a simple and technically feasible means of three-dimensional (3-D) display. It has been said, however, that the binocular picture system is more fatiguing to view than a conventional two-dimensional picture, much as the current television picture. The main objective of this paper is to evaluate quantitatively fatigue caused by binocular stereoscopic picture viewing, to clarify the basic characteristics of this type of picture. Various measurement methods of fatigue have been proposed, and that using the critical flicker frequency (CFF) has found wide use in measurement of mental fatigue and is easy to make. Actual measurement in this study used the CFF value obtained in a descending series of the method of limits, normalized to the value at the start of measurement for each observer, and the CFFs of all observers then averaged. It was found that the measurements produced stable and highly accurate results. CFFs of the observers of a current television picture and a binocular stereoscopic television picture were measured. It was found that the conventional television did not cause a statistically significant decrease in CFF--even over 1 h of viewing--but that the stereoscopic television did cause a significant CFF decrease within 30 min. It was also found that the CFF decreases are related to a subjective feeling of fatigue. From these results, it was concluded that CFF is an effective measure for objectively measuring the fatigue of television observers, including observers of binocular stereoscopic television. Also, the binocular stereoscopic television produced higher fatigue in observers than did the conventional television picture, but it was found that with respect to CFF viewing of around 30 min was allowable.

Accommodation, Ocular↗
PubMed1996

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blotting comparisons of purified myofibrils and whole muscle preparations for evaluating titin and nebulin in postmortem bovine muscle.

Purified myofibril (MF) and homogenized whole muscle (WM) samples were prepared from A maturity market steers. Samples were removed at 0, 1, 3, 7, 14, and 28 d postmortem. The MF and WM samples from all steers were analyzed by SDS-PAGE (5% gels) and by Western blot analysis using monoclonal antibodies to titin and nebulin. The rates of degradation of the intact forms of titin and nebulin, with regard to differences dependent on sample type (MF vs WM), were examined. The results showed that there was very little difference in the rate of postmortem degradation of the intact form of titin or of intact nebulin with respect to the two types of samples examined. Analysis of MF and WM preparations revealed that titin and nebulin were progressively degraded, each at its own rate, with nebulin degrading faster, as postmortem storage time increased. Examination of MF and WM samples showed that the intact form of titin (T1) was absent at the same time postmortem in both sample types. Intact nebulin was not detected in MF and WM preparations at the same time postmortem with respect to sample type examined. Our results indicate that either purified MF or WM samples can be used satisfactorily to analyze the rate of degradation of the intact forms of both titin and nebulin.

Animals↗
PubMed1996

Proteolysis of specific muscle structural proteins by mu-calpain at low pH and temperature is similar to degradation in postmortem bovine muscle.

Postmortem (PM) and mu-calpain-induced degradation of specific skeletal muscle proteins was monitored by SDS-PAGE and Western blotting. Samples were removed from bovine longissimus thoracis (LT) at approximately 45 min PM for the preparation of at-death (0-d) myofibrils (MF). The LT was excised at 1 d PM, vacuum-packaged, and stored at 2 degrees C. Samples were removed for Warner-Bratzler shear force analysis and biochemical analysis at 1, 3, 7, 14, 28, and 56 d PM. The protease mu-calpain was purified from bovine skeletal muscle and used to digest at-death MF at pH 5.6, 4 degrees C, 100 microM CaCl2. Degradation of the proteins titin, nebulin, filamin, desmin, and troponin-T was monitored in the PM and mu-calpain-digested samples by using SDS-PAGE and Western blotting. The PM samples that had significantly lower shear force (LSF) values (P < .05) at 1 d PM exhibited faster degradation of these five proteins than the higher shear force (HSF) samples. In LSF samples, the intact titin band (T1) was absent by 7 d PM and nebulin was absent by 3 d PM. In LSF samples, some filamin was degraded by 3 d PM, but in HSF samples degradation was not apparent until 14 d PM. In LSF samples, desmin was degraded more rapidly PM than in HSF samples. Troponin-T was broken down PM to yield two major polypeptides of approximately 28 and 30 kDa; these polypeptides appeared earlier PM in LSF samples. Degradation products, similar to those observed PM, for all five proteins also were detected in Western blots of mu-calpain-digested MF, suggesting the calpain system plays a key role in PM protein degradation.

Animals↗
PubMed1995

Correlation between lipoprotein(a) and aortic valve sclerosis assessed by echocardiography (the JMS Cardiac Echo and Cohort Study).

An elevated serum level of lipoprotein(a) (Lp[a]) may be an independent risk factor for atherosclerotic disease, but the relation of Lp(a) to aortic valve (AV) sclerosis has not been determined. We measured serum concentrations of Lp(a) and investigated their relation to the presence of echocardiographic AV sclerosis in residents of a rural village in Japan. We measured serum Lp(a) levels in 347 men and 437 women aged 35 to 90 years (mean +/- SD: 62 +/- 11 years) who participated in mass screening examinations in Wara village, Gifu, Japan. AV sclerosis was assessed by long- and short-axis 2-dimensional echocardiographic views and continuous-wave Doppler echocardiography. AV sclerosis was graded as follows: 0 = normal AV; 1 = increased echo density; 2 = thickening or calcific deposits > or = 3 mm; and 3 = same as 2 with mildly restricted motion (pressure gradient < 16 mm Hg). Lp(a) levels ranged from < 1 mg/dl to 153 mg/dl. The 25th, 50th, and 75th percentile values were 7, 16, and 28 mg/dl, respectively. Lp(a) levels were significantly higher in women than in men (p < 0.01), and did not increase significantly with age. The prevalence of AV sclerosis (grades 2 and 3) increased significantly with age (p < 0.001). AV sclerosis was present in 65 (36.1%) of 180 subjects with Lp(a) levels > or = 30 mg/dl and in 77 (12.7%) of 604 subjects with Lp(a) levels < 30 mg/dl (p < 0.001). There were no significant differences in the prevalence of AV sclerosis in terms of sex, blood pressure, or levels of total cholesterol, high-density lipoprotein cholesterol, triglycerides, or blood sugar. We conclude that increased serum levels of Lp(a), as well as aging, are closely related to AV sclerosis.

Adult↗
PubMed1995

Prion disease with 144 base pair insertion in a Japanese family line.

We describe an insert mutation in the prion protein (PrP) gene in a Japanese family line that encodes six octapeptide repeats. This is the second report to date of an inherited prion disease with a 144-base pair insertion, although the order of the repeat sequences differ from that reported for the disease in an English family line. The clinical features, like those of the English patients, were characterized by a slowly progressive generalized dementia with some neurological signs and cortical focal symptoms. Postmortem examination disclosed diffuse atrophy of cerebral gray matter and the cerebellar cortex; histologically, there were marked patchy and regional neuronal loss with astrocytosis in the frontal cortex, amygdala and hippocampus and PrP-immunoreactive plaques in the molecular layer of the cerebellum. These plaques were different from typical kuru plaques. The prion disease in the present Japanese family line is compared with that in the English family line.

Adult↗
PubMed1995

[Influence on glycemic control of improved diabetic gastroparesis by long-term cisapride therapy].

To investigate the effect on glycemic control of improving diabetic gastroparesis, we evaluated symptoms (scored), gastric motor functions (solid and liquid gastric emptying studies and electrogastrography), and glycemic control in 11 patients with diabetic gastroparesis (5 men, 6 women, 50.4 +/- 4.5 years old) before and after treatment with cisapride (15 mg/day p.o., 12 weeks). None of the patients had organic abnormalities on gastrointestinal endoscopy. The dysmotility symptom score (maximum: 18) on cisapride significantly improved from 13.1 to 4.0 (p < 0.01). Retention rates at 15 and 80 minutes after ingestion improved in a solid-food gastric emptying study using a test meal of instant noodles labeled with 37 MBq (1 mCi) technetium-99m (both p < 0.05). Liquid gastric emptying, evaluated using a sulfamethizole technique, also improved but not significantly. Electrogastrography revealed no significant changes after treatment, but the postprandial rate of normal frequency waves tended to increase. Glycemic control was assessed based on HbA1C, fructosamine and M value. There were no significant changes in glycemic control after treatment with cisapride. We conclude that long-term administration of cisapride reduced dysmotility symptoms and improved solid and liquid gastric emptying without adversely affecting glycemic control.

Adult↗
PubMed1994

Increased production of eicosanoids, TXA2, PGI2 and LTC4 in experimental spinal cord injuries.

Arachidonate metabolites have many kinds of bioactivities. Thromboxane A2 (TXA2) stimulates platelet aggregation and vasoconstriction, whereas prostaglandin I2 (PGI2) antagonises its activities. Thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) are determined in biological materials. Production of TXB2, 6-keto-PGF1 alpha and leukotriene C4 (LTC4), which have potent vascular permeability, was measured by radioimmunoassay in experimental spinal cord injured animals. TXB2 level in the rat spinal cord reached a peak concentration of 133.6 +/- 3.8 pmol/g cord, and 6-keto-PGF1 alpha increased to 26.2 +/- 11.7 pmol/g cord 5 minutes after the injury. There was good correlation between TXB2 production and vascular damage as monitored by fluorescein uptake. When OKY-046 ((E)-3-[4-(1-imidazolylmethyl) phenyl]-2-propenoic acid), which selectively inhibits TXA2 synthetase activity, was administered 10 minutes before injury, the increase in TXB2 production was inhibited by more than 80%, but the degree of vascular damage was reduced by only 40%. In the guinea pig spinal cord, LTC4 levels reached a peak concentration of 2.2 +/- 0.4 pmol/g cord 10 minutes after compression, while that of TXB2 reached 146.8 +/- 6.2 pmol/g cord. The increased production of TXB2 was correlated with the degree of compression injury while that of LTC4 production did not. These findings suggest that vasoactive eicosanoids, TXA2, PGI2 and LTC4, play important roles in secondary damage following spinal cord injury, although their roles may be different among species of animals.

6-Ketoprostaglandin F1 alpha↗
PubMed1994

Polysplenia accompanied by major cardiovascular anomalies with prolonged survival.

A 52-year-old female with polysplenia accompanied by major cardiovascular anomalies (a ventricular septal defect, atrial septal defect, persistent left superior vena cava, absent inferior vena cava with a hemiazygos connection and visceral heterotaxia) is reported. She underwent successful surgical treatment and showed prolonged survival.

Abnormalities, Multiple↗