Biomedical subjects

K Imamura

Publications and source records attributed to K Imamura.

At least 73 records · Page 4Linked to original sources

PubMed1999

Analysis for partition equilibrium of amino acid derivatives in aqueous/organic biphasic systems.

The overall partition coefficients of the acid and amine components of amino acid derivatives, the substrates for proteinase-catalyzed synthesis of oligopeptide precursors, in an aqueous/organic biphasic system were studied both experimentally and theoretically. In a single-component system containing either an acid or amine component, the overall partition coefficient was well expressed by a model using the acid dissociation constant and partition coefficients for the non-ionized and ionized forms of the component. The overall partition coefficient in a binary-component system containing both acid and amine components was well simulated by the model when the formation of ion-pair complexes in the organic solvent phase was taken into consideration in addition to the partitioning of the non-ionized and ionized forms of the components. The formation of ion-pair complexes in the organic solvent phase was indicated by an analysis using Fourier transform infrared ray spectroscopy (FT-IR). In addition to the partition equilibrium, the aqueous-phase pH change after partitioning could be predicted by the model.

Journal Article↗

PubMed1999

Adsorption characteristics of tryptic fragments of bovine beta-lactoglobulin on a stainless steel surface.

As a strategy for the analysis of the mode of protein adsorption onto stainless steel surfaces, peptides obtained by tryptic digestion of bovine beta-lactoglobulin were subjected to adsorption experiments after identification of their primary structures. In the presence of 1 mM KOH, the peptides were scarcely adsorbed onto the surfaces of stainless steel particles from the peptide mixture. The adsorption experiments on isolated peptides showed that the affinities of the peptides for stainless steel surfaces in the presence of 1 mM HNO3 were significantly different from each other. Peptides without any acidic amino acid residues were scarcely adsorbed onto the surface, whereas some peptides with acidic amino acid residues were found to be irreversibly adsorbed onto the surfaces in the acidic pH region. As for the latter peptides, the amount adsorbed on the surface increased with increasing ionic strength. These results indicated that the carboxyl groups on the side chains of the peptides play an important role in the adsorption. Furthermore, the adsorption behavior of beta-lactoglobulin itself was found to be very similar to that of one of the latter peptides.

Journal Article↗

PubMed1999

Stability of immobilized thermolysin in organic solvents.

Various factors affecting the stability of thermolysin immobilized by cross-linking with glutaraldehyde were elucidated, particularly in the water-immiscible organic solvents such as ethyl acetate and tert-amyl alcohol. The main reason for enzyme inactivation in water-immiscible organic solvents was found to be autolysis in the water phase, which may surround the enzyme immobilized inside the support. By contrast, in water-miscible organic solvents thermal denaturation was the predominant cause of enzyme inactivation. Courses of inactivation were expressed by second-order kinetics in the initial stage, after which inactivation proceeded at a slower rate. The extent of autolysis was found to strongly depend on the kind of organic solvent, the water content, and type of support and these dependencies were explained by the difference in the amount and state of water inside the support. Thermolysin was immobilized onto Amberlite XAD-7 as a compact aggregate inside the support which may increase the stability of the enzyme. Finally, it was shown that the stability of the immobilized enzyme could be correlated with the logP value for water-miscible organic solvents and with the solubility of water for water-immiscible organic solvents.

Journal Article↗

PubMed1999

Occurrence and significance of decahydroquinolines from dendrobatid poison frogs and a myrmicine ant: use of 1H and 13C NMR in their conformational analysis

Structures for 2,5-disubstituted decahydroquinolines (DHQs) are reported for the two diastereomeric pairs cis-275B (14) and cis-275B' (15) and 5-epi-trans-269AB (18) and trans-269AB (19), all isolated from skin extracts of dendrobatid frogs, and for 5-epi-cis-275B' (16) and 5-epi-trans-275B (17) found in the extracts of virgin queens of a myrmicine ant [Solenopsis (Diplorhoptrum) azteca]. Detection of such DHQs in an ant, their first reported occurrence, strengthens a dietary hypothesis for the origin of the approximately 30 DHQs that have been detected in extracts of frog skin. NMR data on the two conformers of cis-decahydroquinoline permit assignment of ring conformations and stereochemistry to cis-DHQs of the "N-endo" type or the "N-exo" type. These conformations are also assigned on whether H-8a is equatorial or axial as determined with E-COSY or 1D-HOHAHA spectra.

Journal Article↗

PubMed1999

Use of urine samples from healthy humans, nephritis patients or other animals as an alternative to foetal calf serum in the culture of Leishmania (L.) donovani in vitro.

The effect of supplementing in-vitro cultures of Leishmania donovani with urine was investigated. The parasites were isolated from Bangladeshi patients with visceral leishmaniasis. The urine samples used were collected from healthy human donors, patients with nephrotic syndrome, diabetic nephritis (DN) or diabetes mellitus, a dog and a cow. Promastigotes from blood-agar cultures were inoculated into RPMI-1640 basal medium with 10% heat-inactivated foetal calf serum (FCS) and/or 1%-20% urine. The parasites were then counted in a haemocytometer, on days 2, 4, 5, 6, 7, 8, 10, 12 and 14 post-inoculation. From day 4, the numbers of parasites/ml in cultures containing 5% healthy-human urine but no FCS were at least as high as those in cultures containing 10% FCS but no urine (P = 0.191). The wet weights of parasites harvested from mass cultures of the parasites in RPMI-1640 plus 5% healthy-human urine and in RPMI-1640 plus 10% FCS were practically the same. Multiplication of the parasites in the presence of 5% urine from a DN patient was significantly greater (P < 0.01) than that seen with other urine samples at the same concentration or with 10% FCS. The multiplication seen with 8% canine urine was almost the same as with 5% healthy-human urine. Parasites could be maintained in RPMI-1640 plus 5% healthy-human urine for at least 40 days, sub-culturing every 4 days. Urine may be a better and much cheaper stimulant of Leishmania multiplication in vitro than FCS.

Animals↗

PubMed1999

Study on pancreatic insufficiency (chronic pancreatitis) and steatorrhea in Japanese patients with low fat intake.

The incidence of steatorrhea is said to be lower and its grade milder in Japanese because their fat intake is lower than that of Europeans and Americans. Failure to take this into account creates difficulties when attempting to compare data on pancreatic exocrine insufficiency in different countries. The authors examined the incidence and grade of steatorrhea in Japanese chronic pancreatitis (CP) patients whose daily fat intake was <40 g (25 patients) or > or =40 g (35 patients). In addition, 23 CP patients with steatorrhea and daily fecal fat excretion > or =5 g were given a pancreatic enzyme preparation at a dose 3-8 times higher than the usual dose to investigate its effect on fecal fat excretion. Among CP patients whose fat intake was <40 g, the incidence of fecal fat excretion <5 g was 56% and that of fecal fat excretion > or =10 g (severe steatorrhea) was 8%. In CP patients whose fat intake was > or =40 g, the incidences were 27.9 and 34.9%, respectively; a significant increase in the number of affected patients was noted when fat intake was > or =40 g. The fat absorption rate was 76.2% among patients whose fat intake was <40 g and 77.8% among patients whose fat intake was > or =40 g, revealing no significant difference between the two groups. The proportion of CP patients whose fat absorption rate < or =80% was 32% at a fat intake <40 g and 39% at a fat intake > or =40 g, revealing no significant difference between the two groups.

Adult↗

PubMed1999

Endosaccular aneurysm occlusion with Guglielmi detachable coils for obstructive hydrocephalus caused by a large basilar tip aneurysm. Case report.

The authors present the case of a 60-year-old man with obstructive hydrocephalus caused by a large basilar artery tip aneurysm, in whom direct surgical clipping of the aneurysm neck was considered hazardous. After endosaccular aneurysm occlusion, his symptoms (headache, intellectual impairment, and gait disturbance) and ventricular dilation immediately improved without placement of a ventricular shunt. To the authors' knowledge, this is the first case of its kind treated solely endovascularly.

Basilar Artery↗

PubMed1999

[Cardiac events in vasospastic angina: site and morphology of coronary artery spasm is related to the long-term prognosis of vasospastic angina].

To determine whether the site and morphology of coronary artery spasm provoked with acetylcholine can predict the long-term prognosis of vasospastic angina, coronary artery spasm (more than 90% narrowing) provoked with acetylcholine was studied in 66 consecutive patients (56 males, 10 females, mean age 56 +/- 9 years) with vasospastic angina. All patients were followed for 6.7 +/- 0.9 years and the incidence of cardiac events such as sudden death, myocardial infarction or worsened unstable angina was compared with the site and morphology of provoked spasm. The site of spasm was regarded as proximal when spasm occurred in the proximal site of 3 major coronary arteries which was designated as segment 1, 6 or 11, according to the classification of the American Heart Association, and distal in other segments. The morphology of spasm was classified into 3 types, focal (12 cases, localized more than 90% narrowing with adjoining parts constricting less than 25%), diffuse (17 cases, diffuse more than 90% narrowing), and intermediate (37 cases, localized more than 90% narrowing with adjoining parts constricting 25-90%). The site of spasm was classified into 2 types, the proximal group (24 cases) and the distal group (42 cases). Cardiac events occurred in 7 patients during the follow-up period: sudden death in 2, myocardial infarction in 2, and worsened unstable angina in 3. As to the site of spasm, the incidence of cardiac events was 21% (5/24 patients) in the proximal group, significantly higher than 5% (2/42) in the distal group (p < 0.05). As to the site of spasm, the incidence of cardiac events was 41% (5/12) in the focal group, significantly higher than 3% (1/37) in the intermediate group and 6% (1/17) in the diffuse group (p < 0.001). The presence of proximal and focal coronary artery spasm was associated with a significantly higher incidence of cardiac events. The site and morphology of coronary artery spasm provoked with acetylcholine is related to the long-term prognosis of vasospastic angina.

Acetylcholine↗

PubMed1999

[Trends in comprehensive treatment for gynecologic malignancies].

Advances in many areas, including oncology-epidemiology, chemotherapy, diagnosis, surgery, radiology, and clinical research have all had a positive impact on the treatment of gynecologic malignancies, so that today we have achieved an improved quality of life concomitant with increased survival rates in patients. The improvements in therapy for gynecologic malignancies have been in diagnostic procedures, such as tumor markers, molecular biologic methods, and image analysis. Considerable progress has been made in surgical management, from focal excision of primary lesions to minimal debulking surgery after the initial chemotherapy for advanced cancer. Chemotherapy has advanced markedly after the introduction of cisplatin, and various regimens or anticancer drug-analogs of cisplatin, camptotesin, and paclitaxel have been introduced. In recent years, the quality of life of patients with malignancies has been one of the most important factors in treatment. Intensive and combination therapies will be put to greater use for gynecologic malignancy in the future.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1999

Effects of monocular enucleation on parvalbumin in rat visual system during postnatal development.

PURPOSE: To evaluate the hypothesis that the expression of the calcium-binding protein parvalbumin (PV) in a subpopulation of gamma-aminobutyric acid (GABA)ergic neurons is an appropriate molecular marker for the effect on ocular dominance plasticity of monocular deprivation during the postnatal sensitive period. METHODS: Long-Evans rats underwent monocular enucleation immediately before eye opening (postnatal day [P] 14). Immunohistochemical analysis using anti-PV antibody was performed on the superior colliculus (SC) and lateral geniculate nucleus (LGN) at P45. In the visual cortex (VC) developmental changes in immunoreactivity were also examined at the ages of P17, P20, P27, and P45. Northern blot analysis for PV mRNA was also performed at P45. Changes in PV expression in the visual system of these rats were evaluated by use of a computer-based quantitative technique. RESULTS: PV-immunoreactive neurons were present in the SC and VC, whereas only a few were found in the LGN. The monocular enucleation at the onset of the sensitive period markedly reduced PV immunoreactivity in the neuropil of the SC, contralateral to the enucleated eye when examined one month later. No consistent and significant change in PV immunoreactivity was found in either the LGN or the VC. The number of PV-immunoreactive neurons in the VC rapidly decreased to the adult level during the middle of the sensitive period. The expression of PV mRNA in these central visual structures was not affected by early monocular enucleation. CONCLUSIONS: Expression of PV is developmentally regulated, and marked changes in its protein expression in the SC can be induced by monocular enucleation. Contrary to the original hypothesis, monocular enucleation did not consistently affect the expression of PV in the rat VC. The expression of PV is probably regulated by multiple factors, not merely by binocular competition.

Animals↗

PubMed1998

Prognostic and Therapeutic Implications of the MIB-1 Labeling Index in Breast Cancer.

BACKGROUND: Assessment of tumor proliferative activity is considered to be the most powerful prognostic factor aside from axillary lymph node status. The purpose of this study is to assess the clinical value of measurement of proliferative activity using the MIB-1 labeling index in patients with breast cancer. METHODS: Surgical specimens from 36 patients with benign breast disorders and146 patients with breast cancer were investigated. The MIB-1 labeling index wasdetermined on the specimens stained by immunohistochemical methods as much as possible. Clinical factors associated with the MIB-1 labeling index were reviewed. RESULTS: The MIB-1 labeling index for non-proliferative disorders, proliferative disorders, and breast cancer was 3.4 +/-1.9%, 8.9 +/-6.2% and 20+/-12%, respectively. The MIB-1 labeling index and tumor size, lymph node metastasis status, and clinical stage according to the TNM classification correlated significantly. Survival rate was inversely correlated with the MIB-1 labeling index. No patientwith an MIB-1 labeling index of less than 10% had lymph node metastases, and all are alive without recurrence. Patients with an MIB-1 labeling index of over 30% had an extremely poor prognosis. CONCLUSION: The MIB-1 labeling index is very useful for predicting both either extremely good or extremely poor prognosis, and axillary lymph node metastasis

Journal Article↗

PubMed1998

4q33-qter deletion and absorptive hypercalciuria: report of two unrelated girls.

We report on two unrelated girls with multiple malformations, each of whom had a der(4)t(4;?)(q33;?) chromosome--an unbalanced translocation chromosome with deletion of the 4q33-qter segment and addition of a segment of an unknown chromosome. One of the two girls had asymptomatic kidney stones. Both had excess urinary calcium excretion (0.53 and 0.84 mg/mg creatinine, respectively), exaggerated excretion on oral calcium load, and reduced but excessive excretion on restricted calcium intake. The urinary calcium excretion of their parents was normal. Both girls were thus diagnosed to have sporadic absorptive hypercalciuria. It was deduced that the 4q33-qter segment contains the putative gene for absorptive hypercalciuria.

Abnormalities, Multiple↗

PubMed1998

Clinical and cytogenetic remission induced by interferon-alpha in a patient with chronic eosinophilic leukemia associated with a unique t(3;9;5) translocation.

A patient with chronic eosinophilic leukemia and a unique complex chromosomal translocation 46,XY,t(3;9;5)(q25;q34;q33) who had elevated blood interleukin-5 is reported. Complete cytogenetic remission was induced by interferon-alpha after treatment failure with corticosteroids and cytotoxic drugs. Severe cardiopulmonary symptoms due to hypereosinophilia and thromboembolic complication improved dramatically in the first 6 months of interferon therapy. Since it is known that the gene encoding for interleukin-5 resides on the long arm of chromosome 5, it may be possible that the chromosomal translocation in our patient resulted in overproduction of this cytokine, and our findings may be helpful for understanding the pathogenesis of this disorder.

Adult↗

PubMed1998

Effects of high-lipase pancreatin on fecal fat, neutral sterol, bile acid, and short-chain fatty acid excretion in patients with pancreatic insufficiency resulting from chronic pancreatitis.

CONCLUSIONS: Steatorrhea was almost completely stopped and malabsorption of neutral sterols and short-chain fatty acids was reduced by treatment of high-lipase pancreatin in Japanese patients with pancreatic insufficiency whose dietary fat consumption is low. METHODS: Fifteen patients with chronic pancreatitis complicated by steatorrhea who consumed an average of 48 g of dietary fats a day were selected as subjects and given 3 g of high-lipase pancreatin (lipase, 379,800 USP U/g), at each meal (total daily dose is 9 g) for a mean duration of 28.5 d. Fecal output and fecal fat neutral sterol, bile acid, and short-chain fatty acid excretion were determined before and after the course of pancreatin therapy. RESULTS: Pancreatin administration resulted in significant reductions (P < 0.01) in fecal output (from 243.2 to 149.1 g), excretion of fecal fat, (from 12.3 to 3.9 g), animal sterols (from 816.3 to 604.6 mg), and short-chain fatty acids (from 52.6 to 18.5 mM). In contrast, no marked changes were recorded in fecal excretion of beta-sitosterol (a plant sterol), bile acids, or the hydroxy fatty acid fraction. Fecal fat and short-chain fatty-acid excretion showed strong correlations with fecal output.

Adult↗

PubMed1998

Genetics of obesity in KK mouse and effects of A(y) allele on quantitative regulation.

KK mouse is known as a polygenic model for noninsulin-dependent diabetes mellitus with moderate obesity. To identify the quantitative trait loci (QTLs) responsible for the body weight in KK, linkage analysis with 97 microsatellite markers was carried out into 192 F2 progeny, comprising 93 mice with a/a genotype at agouti locus and 99 mice with A(y)/a genotype, of a cross between C57BL/6J female and KK-A(y) (A(y) congenic) male, thereby the influence of A(y) allele on the quantitative regulation of body weight was also examined. In F2 a/a mice, we identified a QTL on Chromosome (Chr) 4, and two loci with suggestive linkage on Chrs 15 and 18. In F2 A(y)/a mice, a QTL was identified on Chr 6, and two loci with suggestive linkage were identified on Chrs 4 and 16. That the QTL on Chr 4 was held in common between F2 a/a and F2 A(y)/a progenies implies that this locus may be a primary component regulating body weight in KK and KK-A(y). These results suggest that the body weight in KK is controlled by multiple genes, and the different combination of loci is involved in the presence of A(y) allele. The QTL on Chr 6 seemed to determine the body weight by controlling fat deposition, because the linkage was identified on body weight and adiposity, and is suggested to be a component involved in the metabolic pathway in obesity caused by the A(y) allele.

Agouti Signaling Protein↗

PubMed1998

Roles of N-methyl-D-aspartate receptors in ocular dominance plasticity in developing visual cortex: re-evaluation.

We have re-examined whether N-methyl-D-aspartate receptors play a specific role in experience-dependent plasticity in kitten visual cortex. A specific antagonist of this glutamate receptor subtype, D,L-2-amino-5-phosphonovaleric acid, was directly and continuously infused into kitten striate cortex for one week concurrently with monocular lid suture. In the hemisphere infused with 50 mM antagonist, we found the usual shift in ocular dominance toward the open eye with only a few binocular cells remaining. The changes were accompanied by an extremely high incidence (38%) of abnormal cells lacking orientation selectivity across different ocular dominance groups. In kitten cortex infused with 10 mM antagonist concurrently with monocular deprivation for a week, recording from a drug-affected region near the infusion centre, we again found the U-shaped ocular dominance distribution with the high incidence of non-selective cells. In antagonist-infused, otherwise normal striate cortex of adult cats, we found that the proportion of binocular cells decreased by one-half in two cellular populations: one recorded during the continuous infusion of 10 mM antagonist under general anaesthesia and paralysis, and the other about two days after stopping the infusion. We also established that in vivo concentrations of chronically infused 10 mM antagonist decreased, not near-exponentially, but linearly with increasing distance from the infusion site. Thus, the effects of a directly and continuously infused, concentrated antagonist of N-methyl-D-aspartate receptors on receptive-field properties of visuocortical cells are complex. The present findings strongly suggest that the antagonist effects in the developing cortex may be due primarily to blockade of normal synaptic transmission rather than specific disruption of an experience-dependent mechanism underlying ocular dominance plasticity.

2-Amino-5-phosphonovalerate↗

PubMed1998

Outcome of total hip replacement in Japan and England. Comparison of two retrospective cohorts.

Two retrospective cohorts of patients who had undergone a primary total hip replacement (THR) were studied in Japan and England. We analyzed information from hospital case notes and self-administered questionnaires. THR was highly effective in both countries, with significant improvements in morbidity and health status. There were, however, important differences in clinical management and outcome. Japanese patients were more likely to be treated under regional anesthesia by means of an anterior/anterolateral incision, to be transfused, to have a prosthesis implanted without cement, and to stay longer in the hospital. A higher rate of serious in-hospital complications occurred in England, mostly due to the high frequency of hypotension. The incidences of minor complications were consistent with known differences in risks between the two countries. The persistent postoperative perception of limping reported by the English patients was unexpected.

Aged↗

PubMed1998

A 75-kD autoantigen recognized by sera from patients with X-linked autoimmune enteropathy associated with nephropathy.

Autoimmune enteropathy (AIE) is a rare disorder characterized by intractable diarrhoea and antienterocyte autoantibody. In this study, we detected a 75-kD autoantigen which distributed through the whole intestine and the kidney, as assessed by Western blot analysis using sera from two unrelated cases of AIE associated with nephropathy. Our results suggest that the detection of the autoantibody against the 75-kD antigen has a diagnostic value in AIE and that the autoimmune reaction against the 75-kD antigen may be implicated in the development of intestinal and renal tissue damage in this rare disorder.

Antigens↗