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Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 451 records · Page 25Linked to original sources
PubMed1995

Dermal histology of hairless rat derived from Wistar strain.

The dermal histology of 9-week-old hairless rats derived from Wistar rats was investigated and compared with that of age-matched Wistar rats. Skin samples were taken from 4 portions: the head, dorsal and ventral skin, and foot pad. The epidermis of the 3 portions other than the foot pad was thicker in hairless rats than in Wistar rats. The hair canals of hairless rats contained lamellar cornified tissues instead of hair, and some of the hair follicles deep in the dermis exhibited cyst formation. S-100-immunoreactive cells were detected in the basal layer of epidermis and their number in hairless rats was greater than that in Wistar rats. Ultrastructurally, electron-lucent cells, i.e. Langerhans cells, which contained Birbeck granules and/or cored tubules, were observed more frequently in the epidermis of hairless rats than in that of Wistar rats. Some cells in one hairless rat, which had similar characteristics to Langerhans cells without Birbeck granules, contained confronting cisternae.

Animals↗
PubMed1995

Dorsal skin reactions to sunlight and artificial ultraviolet light in hairless descendants of Mexican hairless dogs.

Dorsal skin reactions to irradiation with two different types of ultraviolet (UV) light sources (sunlight and artificial UV light) were investigated in hairless descendants of Mexican hairless dogs. The total energy dose of solar UV exposure and artificial UV irradiation was 90 kJ/m2 and 40 kJ/m2, respectively. Histological examinations were done up to 7 days after UV irradiation (7 DAI). At 1 DAI, the solar UV-exposed skin did not show marked changes, while artificial UV irradiated skin exhibited a visible erythematous reaction and prominent histological alterations such as epidermal thickening, appearance of sunburn cells and deformation elastic fibers. At 4 DAI of solar UV-exposure, the skin color became moderately dark and noticeable pigmentation developed in the epidermis. In contrast, at 4 DAI of artificial UV irradiation, there still remained moderate degeneration in the epidermis and dermis, and delayed tanning was weak. At 7 DAI of solar exposure, delayed suntan reactions became more prominent. Histologically, there were heavy pigmentation of melanin granules mainly in the stratum basale. On the other hand, artificial UV irradiated skin showed less pigmentation. Thus, solar exposure provoked remarkable pigmentation while artificial UV irradiation brought about severe sunburn reactions in the dorsal skin of hairless dogs.

Animals↗
PubMed1995

Ultrastructure of the dorsal skins of hairless descendants derived from Mexican hairless dogs.

Ultrastructural characteristics of the dorsal skin of hairless descendants derived from Mexican hairless dogs (3-month-, 1-year- and 5-year-old) were investigated and compared with those of age-matched beagles. Except that beagles had no melanocytes in epidermis, there was no essential difference in ultrastructural characteristics of epidermis between hairless dogs and beagles. In the Stratum basale of epidermis of hairless dogs, a small number of melanocytes and a few Langerhans cell (LC)-like cells were observed among keratinocytes. Melanocytes contained many melanosomes and a few premelanosomes. LC-like cells were characterized by electron-lucent cytoplasm and lobulated nucleus and lacked melanin granules, tonofilaments and desmosomal attachments. Unlike LC in humans and rodents, these LC-like cells did not contain Birbeck granules. Although age-related ultrastructural changes of dorsal skin were generally not clear both in hairless dogs and in beagles, cells containing melanin granules were not infrequently observed among dermal collagen bundles in 5-year-old hairless dogs.

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

Nystagmus measured by ENG after stapes surgery.

Much attention has been paid to hearing results after stapes surgery, but the risks of vestibular disturbance has not been extensively studied. Postoperative spontaneous nystagmus was measured daily at bedside by portable ENG in order to evaluate the vestibular damage from stapes surgery. Thirteen patients underwent primary stapedotomy or stapedectomy from August 1, 1992 to June 30, 1993. Nystagmus toward the operated ear was observed in 3 cases, that toward the opposite ear in 2 cases, that changing from toward the operated ear to toward the opposite ear in 2 cases, that changing from toward the opposite ear to toward the operated ear in 2 cases and no nystagmus in 4 cases. There was no relationship between duration of nystagmus and that of dizziness. Nystagmus was thought to be due to the following: i) inner ear damage by operation, ii) postoperative perilymphatic fistula, iii) floating footplate, and iv) stimulation of hair cells by high potassium ion in the perilymph due to blood flow into the inner ear.

Adolescent↗
PubMed1995

Glutamate receptor gene family expressed in vestibular Scarpa's ganglion of rat.

The expression of glutamate receptor gene family in the vestibular Scarpa's ganglion (VG) of rat was determined using molecular biological techniques including reverse transcription (RT), polymerase chain reaction (PCR), amplification, DNA sequencing, and immunocytochemistry. Oligonucleotide primers were designed from the previously cloned sequences of the AMPA-selective glutamate receptors (GluR1-4), KA-selective glutamate receptors (GluR5-7, KA1&2), NMDA-selective glutamate receptors (NMDAR1&2), and metabotropic glutamate receptors (mGluR1-4). The cDNAs synthesized from the VG mRNAs were amplified with the specific primers for the subunits of each glutamate receptor gene family. Analysis of the nucleotide sequences of the amplified cDNAs identified the expression of GluR1-4, GluR5, and NMDAR1 in the VG. Sequence analysis identified the expression of all the four subunits of GluR1-4 in two alternative spliced versions named "flip" and "flop" in the VG. In an immunocytochemical study, a large number of VG neurons showed only GluR2/3-like immunoreactivity (IR) while GluR1- or GluR4-IR could not be determined in the VG. The present study suggested that the subunits of GluR1-4, GluR5, and NMDAR1 may be assembled into the hetero-oligomeric glutamate receptor complex in the VG and that the VG neuron-specific stoichiometry of the receptor complex may be functionally significant for the afferent signal transduction in the rat peripheral vestibular system.

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↗
PubMed1995

Distribution of viral RNA in the spinal cord of DBA/2 mice developing biphasic paralysis following infection with the D variant of encephalomyocarditis virus (EMC-D).

DBA/2 mice infected with the D variant of encephalomyocarditis virus (EMC-D) (10(1) PFU/head) developed biphasic hind limb paralysis. As a first step in clarifying its pathogenesis, we examined the distribution of viral RNA in the spinal cord using in situ hybridization. At 3 days post inoculation (DPI), in the spinal cord of mice showing slight paralysis, viral RNA was observed in capillary endothelial cells and a few adjacent glia cells in the funiculus lateralis from thoracic to lumbar enlargement. At 7 DPI, in the spinal cord of mice showing apparent paralysis, viral RNA was observed in a larger number of glia cells in the demyelinated lesion associated with infiltration of macrophages in the funiculus lateralis and in a small number of degenerated neurons in the cornu ventrale. In the funiculus lateralis, viral RNA could not be observed after 28 DPI. On the other hand, viral RNA was observed in degenerated neurons in the cornu ventrale of mice showing the second phase paralysis at 42 DPI. Many CD4+T cells infiltrated around these degenerated neurons. These results suggest that: (1) the viral entry zone was the capillary endothelial cells in the funiculus lateralis; (2) first phase paralysis was due to demyelination caused by EMC-D and associated with macrophage infiltration; (3) second phase paralysis was due to degeneration of motor neurons bearing viral RNA associated with infiltration by CD4+T cells.

Animals↗
PubMed1995

[Imaging science and technology in diagnostic radiology: expectations in the second century of Roentgen's discovery of X-rays].

During the first century since the discovery of X-rays by Roentgen in 1885, imaging technology has contributed significantly to the progress of diagnostic radiology, mainly by providing various methods and techniques for production of diagnostic images. In the next century, it is expected that imaging science and technology will contribute to the most important process of diagnostic decision makings by radiologists and physicians by providing quantitative analyses of medical images using high-speed computers. The computer output may be used as a "second opinion" to assist radiologists' interpretation of images. This concept has been investigated as computer-aided diagnosis (CAD) during the last ten years in chest radiography and mammography for detection of lesions and characterization of normal and abnormal patterns. The aim of CAD is to improve the accuracy and the consistency of radiologic diagnoses. In this article, recent results are presented on the detection of lung nodules and pneumothoraces as well as quantitative analyses of interstitial infiltrates and cardiomegaly in chest radiographs. In mammography, CAD schemes are being developed for detection of clustered microcalcifications and masses. Recently, the prototype mammography intelligent workstation has been implemented in the clinical section of our department and initial clinical results from screening cases appear promising.

Diagnosis, Computer-Assisted↗
PubMed1995

Protective effects of macrophage-derived interferon against encephalomyocarditis virus-induced diabetes mellitus in mice.

The involvement of macrophages in protection against diabetes mellitus in mice of BALB/c (susceptible) and C57BL (resistant) strains infected with the B (non-diabetogenic) or D (highly diabetogenic) variant of encephalomyocarditis (EMC) virus was examined. Pretreatment with the B variant of EMC virus (EMC-B), avirulent interferon (IFN) inducer, or Corynebacterium parvum inhibited diabetes in BALB/c mice infected with the D variant of EMC virus (EMC-D). Treatment of C57BL mice with carrageenan to compromise macrophage function rendered C57BL mice susceptible to EMC-D-induced diabetes. In macrophage culture for BALB/c mice, EMC-B induced IFN at an earlier stage than did EMC-D. The C57BL mouse-derived macrophages produced more IFN than did BALB/c mouse-derived macrophages after stimulation with EMC-D. Moreover, C. parvum increased IFN production in macrophage cultures from BALB/c mice, whereas carrageenan inhibited that in macrophage cultures from C57BL mice. These results suggest that IFN derived from macrophages may have an important role in protecting mice against EMC virus infection.

Animals↗
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↗