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Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 37 records · Page 2Linked to original sources
PubMed1995

Encephalomyocarditis (EMC) virus infection in the common vole, Microtus arvalis.

Encephalomyocarditis (EMC) virus infection in the common vole was examined for the first time. Sixteen 8-week-old males inoculated intraperitoneally with 10(5) plaque-forming units (pfu)/animal of the D variant of EMC virus were killed 3 and 7 days after inoculation (3 and 7 DAI). Viral replication was detected in the brain (10(5) pfu/g), heart (10(4) pfu/g) and pancreas (10(7) pfu/g) of all 8 animals at 3DAI. It was found in the pancreas (10(3) pfu/g) of all 8 animals and in the brain (10(4) pfu/g) of 2 of 8 animals at 7 DAI. Histopathological changes were observed in the brain (mild mononuclear cell infiltration around capillaries and sporadic pyknosis of neurons), heart (minimal myocardial necrosis) and pancreas (prominent acinar cell necrosis with inflammatory exudation) at 3DAI. At 7 DAI, replacement of necrotic tissues by mesenchymal cells and regeneration of acinar cells were conspicuous in the pancreas. Throughout the experimental period, no evidence for diabetogenic effect was found.

Animals↗
PubMed1995

Long-term effects of dietary fiber supplementation on serum glucose and lipoprotein levels in diabetic rats fed a high cholesterol diet.

We have shown that cholesterol-fed diabetic rats developed atheromatous lesions in the aorta and coronary arteries, which were not observed in cholesterol-fed diabetic rats receiving concomitant supplementation with 15% glucomannan, a soluble dietary fiber concentrate. The present study was designed to examine the effects of the dietary fiber supplementation on serum levels of glucose and lipoproteins in cholesterol-fed diabetic rats. Feeding a diet containing 1.5% cholesterol (wt/wt) and 0.37% cholic acid for 18 weeks to rats made diabetic by streptozotocin (35 mg/kg body weight, iv) produced moderate hyperglycemia and moderate hypercholesterolemia, the latter being characterized by high concentrations not only of low density lipoproteins but also intermediate density lipoproteins and very low density lipoproteins. These changes in serum lipoproteins and hyperglycemia were substantially reduced by 18 weeks of supplementation with glucomannan but high density lipoprotein cholesterol and triglyceride levels did not change after feeding a cholesterol-rich diet in the presence or absence of glucomannan supplementation. These results suggest that amelioration in hyperlipoproteinemia and hyperglycemia induced by the dietary fiber supplementation may help retard or prevent the atheromatous formation found in cholesterol-fed diabetic rats.

Animals↗
PubMed1995

Ca2+ increase and pH decrease induced by hypochlorous acid in single quiescent myocytes isolated from rat ventricles.

Cytosolic free calcium concentration ([Ca2+]i) and intracellular pH (pHi) were simultaneously measured with a fluorescence technique using fura-2 and BCECF. Hypochlorous acid (HOC1) increased [Ca2+]i and decreased pHi of single quiescent myocytes isolated from rat ventricles. The HOC1-induced changes in [Ca2+]i and pHi (delta [Ca2+]i and delta pHi) were 129 +/- 18nM and 0.18 +/- 0.02 (mean +/- SD), respectively, with 200 microM HOC1. A positive linear correlation was obtained between delta [Ca2+]i and delta pHi under various extracellular Ca2+, pH, and Na+ conditions. Chelation of extracellular Ca2+ depressed only one-fourth of delta [Ca2+]i, and Ca2+ antagonists (verapamil and nifedipine) did not reduce delta [Ca2+]i, indicating that delta [Ca2+]i originates mainly from intracellular Ca2+ stores. A disulfide-reducing reagent, 1,4-dithiothreitol (DTT), recovered the increased [Ca2+]i and decreased pHi to the control levels. The simultaneous changes in [Ca2+]i and pHi induced by HOC1 and the simultaneous restoration of the normal [Ca2+]i and pHi in cardiac myocytes.

Animals↗
PubMed1995

Assessment of auditory and vestibular functions after vestibular neurectomy for Menière's disease.

Fourteen patients (12 Meniere's disease, one delayed endolymphatic hydrops and one labyrinthitis) suffering from intractable vertigo were treated with retrosigmoid vestibular neurectomy (RSVN) in our institute. Dizziness was controlled completely in all patients. Hearing was preserved in 91.7% of the cases with pure tone threshold deteriorating by more than 10 dB in one case, remained unchanged in 10 cases and improved in one case during long term observation. Substantial decrease of tinnitus was observed in 78.6%. Vestibular compensation was chronologically analyzed with a stabilometer, ENG and vestibular rotation test (0.01-0.64 Hz). Vestibular compensation under static conditions was accomplished within 2 weeks, except for spontaneous nystagmus measured in the dark. Asymmetry of vestibulo-ocular reflex was noted 2 weeks after the operation but had disappeared after 4 weeks. However, for over 2 years the VOR time constant remained lower (4.3-5.2 s) than the pre-operative value (8.2 s). Electro-cochleogram (ECoG) was recorded before and after RSVN. The -SP/AP ratio tended to increase after RSVN in the operated ear, though there was no change in the contralateral ear. The efferent olivo-cochlear bundle was thought to play a potential role in this increase of the -SP/AP ratio.

Adult↗
PubMed1995

Age-related changes of aorta in Syrian hamsters of APA strain.

Age related changes in thoracic aorta (TA) and abdominal aorta (AA) of male APA hamsters from 3 to 12 months of age were examined morphometrically and ultrastructurally. The nuclear density of smooth muscle cells (SMCs) was larger in AA than in TA, and it decreased with advancing age. In contrast, the collagen fibre density was larger in TA than in AA, and it increased correlatively with aging, especially in TA. Electron microscopic examinations revealed that subendothelial cystic spaces and aggregations of fragments of elastic and collagen fibres were found at 3 months of age and progressed with advancing age in TA, while they were not evident in AA even at 12 months of age. Irregularity of medial SMC contours and an amount of SMC-associated collagen fibres were more prominent in TA than in AA throughout the experimental period. Degenerative changes of endothelial cells and medial SMCs progressed with aging in both TA and AA, and degenerated SMCs were characterized by aggregations of swollen mitochondria.

Aging↗
PubMed1995

Vascularized allogeneic joint, muscle, and peripheral nerve transplantation.

Joint, muscle, and peripheral nerve allotransplantation was done with short-term cyclosporine immunosuppression. To investigate the effectiveness of this regimen, the allografts were examined after withdrawal of cyclosporine. Using inbred rats, vascularized orthotopic allotransplantation of the knee joint, rectus femoris muscle, and great saphenous nerve was done across a major histocompatibility complex barrier. Cyclosporine was administered for 4 to 6 weeks postoperatively, and the grafts were observed until Week 12. Long-term administration of cyclosporine and nonvascularized transplantation were used as controls. Although rejection of the allografts could be delayed for 2 to 3 weeks after the withdrawal of cyclosporine, all transplanted joints, muscles, and nerves eventually were rejected completely and immunotolerance could not be induced. The joint allografts at first achieved bony union, but eventually were destroyed because of pathologic fractures. In the group treated with long-term immunosuppression, the allografts showed no rejection and functional improvement was obtained. However, rats given a high dose (10 mg/kg per day) of cyclosporine died from adverse effects of the drug by Week 12. In the nonvascularized treatment group, the results were poor in every patient, and the need for graft vascularization for skeletal tissue allotransplantation was confirmed.

Animals↗
PubMed1995

[A case of simultaneous treatment with mitral valve replacement and aorto-coronary bypass grafting of hypertrophic obstructive cardiomyopathy and coronary artery disease].

A case of surgical treatment of coexistent hypertrophic obstructive cardiomyopathy (HOCM) and coronary artery disease (CAD) in a 65-year-old male patient is reported. He had been diagnosed as HOCM and treated conservatively with beta-blocker and Ca-antagonist, but his complaints of chest oppression and palpitation had increased. Echocardiography revealed a systolic anterior motion of the mitral valve and mitral regurgitation. Cardiac catheterization showed a severe mitral regurgitation and peak systolic pressure gradient of 35 mmHg between the left ventricular and systemic artery. In addition, selective coronary angiography demonstrated a 99% stenosis in segment 7. He underwent aortocoronary bypass grafting and concomitant mitral valve replacement, and marked symptomatic and hemodynamic benefit could be achieved. This case shows the coexistence of HOCM and CAD in the same patient and suggest not only HOCM but also CAD should be routinely examined in the patient with angina, particularly when operative management is contempted. This case further suggests that simultaneous treatment of both diseases is more beneficial than single treatment of CAD or HOCM.

Aged↗
PubMed1995

In vivo 31P magnetic resonance spectroscopy for evaluation of testicular function in cryptorchid rats.

PURPOSE: To assess in vivo metabolism of rat testicles in experimental cryptorchidism, we used 31P magnetic resonance (MR) spectroscopy and compared testicular MR spectroscopic parameters with flow cytometric DNA analysis. MATERIALS AND METHODS: In vivo 31P MR spectroscopy and flow cytometric DNA analysis of rat testis were performed before and during 14 days of experimental cryptorchidism. RESULTS: The testicular phosphomonoester (PM)/ATP ratio showed a transient increase when multinuclear giant cells appeared in the seminiferous tubules. However, the ratio returned to the preoperative level when these cells disappeared. The phosphodiester (PD)/ATP ratio gradually decreased and the inorganic phosphate (Pi)/ATP ratio slowly increased. DNA flow cytometry showed a decrease in the percentage of haploid cells and an increase in the percentage of diploid cells from 7 days after cryptorchidism. The percentage of tetraploid cells did not change before and during cryptorchidism. CONCLUSION: This study indicates that in vivo 31P MR spectroscopy in combination with flow cytometric DNA analysis provides useful biochemical and histological information for evaluation of testicular function.

Animals↗
PubMed1995

Comparison of plasma total plasmin activities in male and female hypertensive rats.

Plasma total plasmin activity in spontaneously hypertensive rats (SHR) was lower than in normal Wistar rats, and in male SHR, plasmin activity was higher than that in females. However, this sex-related difference in SHR was less than that observed in our previous study in normal Wistar rats. Furthermore, we and others have reported higher levels of coagulant functions in male than in female rats. These studies were taken to indicate that there is a greater necessity for higher fibrinolytic activity in males than in females. The results of the present study suggest that hypertension is a risk factor of thrombosis in view of the increased fibrinolytic activity, and in SHR there is also a sex-related difference in plasma total plasmin activity.

Amino Acid Sequence↗
PubMed1995

[Surgical treatment of ruptured aneurysm of the sinus Valsalva].

A case of 31-year-old man with ruptured aneurysm of the sinus Valsalva into right atrium originating from noncoronary sinus (Konno's classification type IV) was presented. Patch closure of the defect was carried out through aortotomy followed by resection and direct closure of the aneurysm from right atrium. When placing the patch, pledgetted mattress sutures were passed to the aortic annulus from left ventricle to aorta. It could avoid distortion of aortic valve cusp. Attempting surgical treatment for this type of aneurysm, repair of the defect should be performed through aortotomy to ensure the repair and avoid recurrence of aneurysm, injury to aortic valve and conduction system. Repair from aorta is mandatory, and it is also necessary to open right atrium for the exact inspection of tricuspid valve.

Adult↗
PubMed1994

Normal differentiation of rat brown adipocytes in primary culture judged by their expressions of uncoupling protein and the physiological isoform of glucose transporter.

We examined the effects of dexamethasone (DEX) on the expressions of key proteins concerned with energy metabolism in brown adipocytes during their differentiation in primary culture. Transcripts of the uncoupling protein (UCP), lipoprotein lipase (LPL) and CCAAT enhancer binding protein alpha (C/EBP alpha) genes were observed in brown adipocytes cultured in the presence of insulin and thyroid hormones but in the absence of DEX. However, the mRNA level of UCP decreased with the culture period after confluence, and significant mRNA encoding type-1 glucose transporter (GLUT1) was detected in brown adipocytes cultured without DEX, whereas type-4 glucose transporter (GLUT4) was predominantly expressed in mature brown adipocytes in vivo. In contrast, DEX added after confluence consistently elevated the mRNA levels of UCP, LPL and C/EBP alpha, and repressed the level of GLUT1 in a manner synchronized with increase in the level of GLUT4. Therefore, it is concluded that DEX as well as insulin and thyroid hormones is essential for differentiation of brown adipose precursor cells into mature cells that are similar to brown adipocytes in vivo.

Adipocytes↗
PubMed1994

Therapeutic effect of adriamycin encapsulated in long-circulating liposomes on Meth-A-sarcoma-bearing mice.

Long-circulating liposomes modified with a uronic-acid derivative, palmityl-D-glucuronide (PGIcUA), have been developed previously for the passive targeting of liposomes to tumor tissues. In this study, we examined the therapeutic effect of adriamycin (ADM) encapsulated in PGIcUA liposomes composed of dipalmitoylphosphatidylcholine (DPPC), cholesterol (Chol) and PGIcUA (molar ratio, 40/40/10) since this amount of PGIcUA was enough to endow liposomes with long-circulating activity. Long-circulating activity was also observed with palmityl-D-galacturonide (PGalUA) modified liposomes, suggesting that uronic acid plays an important role in preventing liposomes from being trapped in the reticuloendothelial system (RES). ADM was loaded in liposomes by a remote-loading method. Free or liposomal ADM was injected i.v. into BALB/c mice bearing s.c.-implanted Meth-A sarcoma. The liposomal formulation was efficient for reducing tumors, prolonging survival time and curing the animals, especially in the case of large tumors where free ADM was not. Furthermore, PGlcUA liposomes were more effective than conventional liposomes containing dipalmitoylphosphatidylglycerol (DPPG) instead of PGlcUA for prolonging survival time in mice. It might therefore be appropriate to use PGlcUA liposomes as the carriers of anticancer drugs.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1994

Existence of an enzymatic pathway furnishing arachidonic acid for prostaglandin synthesis from arachidonoyl CoA in rabbit kidney medulla.

We examined whether arachidonoyl CoA (AA-CoA) can be a possible supplier of arachidonic acid (AA) for prostaglandin (PG) synthesis in rabbit kidney medulla. AA-CoA was preincubated with or without the 105,000 g supernatant (cytosol) fraction from the kidney medulla for 5 min at 37 degrees C followed by the incubation with the microsomal fraction (0.5 mg protein) (a rich source of PG synthesizing enzymes) in the presence of reduced glutathione and hydroquinone for 5 min at 37 degrees C, and the formed PGE2, F2 alpha and D2 were measured by high-pressure liquid chromatography using 9-anthryldiazomethane for derivatization. The addition of AA-CoA (20 nmol) alone changed the total PG formation (the sum of PGE2, F2 alpha and D2) from 0.14 to 1.55 ng. When the cytosolic fraction (10-100 microliters) was added together with 20 nmol-AA-CoA in the preincubation mixture, total PG formation was further increased 2- to 3-fold compared to AA-CoA alone. Experiments utilizing AA, instead of AA-CoA and boiled cytosolic fraction revealed that the stimulatory action of the cytosolic fraction on the AA-CoA-induced PG synthesis may not be due to the effect on cyclooxygenase activity and due to long-chain acyl CoA hydrolase. These results show that long-chain acyl CoA hydrolase which hydrolyzes AA-CoA to AA is present in the cytosol of rabbit kidney medulla and suggest that this enzyme activity is a potential mediator of supply of AA for PG synthesis in this region.

Acyl Coenzyme A↗
PubMed1994

A deletion in the second cytoplasmic loop of GluR3 produces a dominant negative mutant of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor.

We have characterized a GluR3 mutant (sGluR3) which has a 33-amino acid deletion in its second cytoplasmic loop (deficit from Tyr-715 to Gly-747 of GluR3-flop). Xenopus oocytes injected with cRNA transcribed from cDNA for this mutant did not respond to kainate and glutamate (each 100 microM) at a holding potential of -70 mV. In oocytes coinjected with cRNAs for this mutant and for normal alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor subunits, the current response to both kainate and glutamate was much weaker than that observed in oocytes injected with cRNA for the normal subunits alone. This inhibitory action was not accompanied by a significant change of ED50 value and shape of the I-V curve and was AMPA receptor-specific. A comparable deletion in GluR1 produced a mutant with properties similar to those of sGluR3, while a 33-amino acid deletion elsewhere in the second cytoplasmic loop of GluR3 (Met-674 to Phe-706) gave a mutant with a weaker effect. These results suggest that sGluR3 acts as a dominant negative mutant on the functional expression of normal AMPA receptors in oocytes by assembling with the normal subunits to produce an essentially nonfunctional receptor complex.

Amino Acid Sequence↗
PubMed1994

Potential usage of thermosensitive liposomes for macromolecule delivery.

Since transient swelling during phase transition of liposomes with hyper-osmotic internal aqueous phase may cause permeation of large molecules through the lipid bilayer, this type of liposomes can be useful for delivering macromolecules. In fact, thermosensitive liposomes containing an internal solution with osmotic pressure 2-fold higher than the physiologic level and sized through 200-nm pore, released encapsulated macromolecules such as dextran (M(r) 144,000) effectively when they were incubated at 40-42 degrees C. These liposomes were stable in the presence of serum compared to the liposomes with internal osmotic pressure more than 3-fold higher than the physiologic level.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1994

[Preliminary clinical evaluation of computer-aided diagnosis in digital chest radiography].

We are developing computer-aided diagnosis (CAD) schemes for chest radiography with which to alert radiologists to possible lesions, and thus potentially improve diagnostic accuracy. Although preliminary results of individual CAD schemes have been encouraging, CAD is still at an early stage of its development. Therefore, we applied our CAD programs in a clinical environment and evaluated its potential usefulness and limitations. CAD programs including automated detection of cardiomegaly, analysis of interstitial infiltrates, and detection of lung nodules were applied to 310 consecutive chest radiographs. CAD results for cardiomegaly and interstitial infiltrates were evaluated subjectively by radiologists and physicists for clinical accuracy and technical problems, respectively, depending on the correspondence of the CAD output to the nature and location of important findings influencing the radiologic diagnosis. CAD results for lung nodules were evaluated objectively by taking into account the number of false positives and true positives. For detection of cardiomegaly, 71% of evaluated cases were judged to be acceptably accurate in terms of clinical accuracy. For analysis of focal and diffuse interstitial infiltrates, 87% and 61% were acceptably accurate, respectively. For detection of lung nodules, 61% were acceptably accurate. More than 70% of CAD output was judged to be possibly accurate in terms of technical aspects. Technical problems were related to failure to detect subtle abnormalities and the occurrence of false positives caused by normal anatomical structures. We believe that CAD has the potential to be a valuable aid for radiologists in clinical practice, if certain technical problems can be overcome and if optimal operating points can be defined for clinical use.

Diagnosis, Computer-Assisted↗