Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 109 records · Page 6Linked to original sources

PubMed2000

Morphological and functional changes of rabbit mesenteric artery cultured with fetal bovine serum.

The aim of this study was to examine the morphological and functional changes in rabbit mesenteric arterial tissue cultured with fetal bovine serum. In the endothelium-denuded arteries cultured under a serum-free condition for one week (serum-free arteries), morphology of the smooth muscle layer was intact. In the serum-free arteries, high K+ -induced contraction did not change but norepinephrine-induced contraction slightly decreased compared with that in the freshly isolated arteries, whereas the sensitivity to these stimulants was significantly augmented. In the medial layer of the arteries cultured with 10% fetal bovine serum for one week (serum-treated arteries), proliferation, disorientation and death of smooth muscle cells were observed. In the serum-treated arteries, both the amplitude of contractions induced by high K+ and norepinephrine and the sensitivity to these stimulants were significantly reduced compared with those of the serum-free arteries. The reduced norepinephrine-induced contraction in the serum-treated arteries was partially recovered by adding NG-monomethyl-L-arginine (L-NMMA), a nitric oxide (NO) synthase inhibitor, to the assay medium. In alpha-toxin permeabilized arteries, the amplitude of Ca2+ -induced contraction and the sensitivity of the contractile apparatus to Ca2+ were significantly reduced after serum-treatment. These results suggest that chronic serum-treatment of rabbit mesenteric arteries impairs muscle contractility by the morphological and phenotypic changes in smooth muscle cells. NO production in smooth muscle cells is also responsible for the decreased contractility after the serum-treatment.

Animals↗

PubMed2000

Inhibition of rho-associated kinase results in suppression of neointimal formation of balloon-injured arteries.

BACKGROUND: Rho-associated kinase (ROCK), an effector of small GTPase Rho, regulates vascular tone via a calcium sensitization mechanism and plays a key role in the pathogenesis of hypertension. However, its role in vascular growth remains unclear. METHODS AND RESULTS: Y-27632, a specific ROCK inhibitor, and the overexpression of dominant-negative ROCK suppressed the mitogen-induced DNA synthesis of cultured vascular smooth muscle cells (VSMCs), which indicates the essential role of ROCK in the control of VSMC proliferation in vitro. Y-27632 also suppressed the chemotaxis of VSMCs. Male Wistar rats were systemically given Y-27632 (35 to 70 mg. kg(-1). day(-1)) through an intraperitoneal infusion. The neointimal formation of balloon-injured carotid arteries was significantly suppressed in Y-27632-treated rats (intima/media ratio, 0.22+/-0.02) compared with vehicle-treated rats (intima/media ratio, 0.92+/-0.21) or hydralazine-treated rats with a similar blood pressure decrease (intima/media ratio, 1.03+/-0.15). The phosphorylation of myosin phosphatase and myosin light chain was elevated in injured arteries in a Y-27632-sensitive manner, indicating the augmentation of ROCK activity in neointimal formation. The downregulation of the cyclin-dependent kinase inhibitor p27(kip1) in injured vessels was reversed by Y-27632 treatment, reflecting the antiproliferative effect of ROCK inhibition in vivo. CONCLUSIONS: We conclude that ROCK plays a key role in the process of neointimal formation after balloon injury. Thus, the inhibition of ROCK may be a potential therapeutic strategy for treating vascular proliferative disorders and hypertension.

Amides↗

PubMed2000

Neural plasticity detected in short- and long-term cochlear implant users using PET.

The interaction of listening to words and watching sign language in short-term and long-term cochlear implant (CI) users who have learned sign language after becoming deaf was measured using PET. In short-term CI users the auditory cortex was inactive while in long-term CI users it was fully activated with the simultaneous presentation of auditory and visual input. The result suggests the possibility that the interference of rival modalities may be diminished with experience and the preference switchover from the visual input to the auditory input could be accomplished by means of the neural plasticity persisting in the mature human auditory cortex.

Adolescent↗

PubMed2000

Anchoring proteins confer G protein sensitivity to an inward-rectifier K(+) channel through the GK domain.

Anchoring proteins cluster receptors and ion channels at postsynaptic membranes in the brain. They also act as scaffolds for intracellular signaling molecules including synGAP and NO synthase. Here we report a new function for intracellular anchoring proteins: the regulation of synaptic ion channel function. A neuronal G protein-gated inwardly rectifying K(+) channel, Kir3.2c, can not be activated either by M(2)-muscarinic receptor stimulation or by G(betagamma) overexpression. When coexpressed with SAP97, a member of the PSD/SAP anchoring protein family, the channel became sensitive to G protein stimulation. Although the C-terminus of Kir3. 2c bound to the second PDZ domain of SAP97, functional analyses revealed that the guanylate kinase (GK) domain of SAP97 is crucial for sensitization of the Kir3.2c channel to G protein stimulation. Furthermore, SAPAP1/GKAP, which binds specifically to the GK domain of membrane-associated guanylate kinases, prevented the SAP97-induced sensitization. The function of a synaptic ion channel can therefore be controlled by a network of various intracellular proteins.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Effects of aging on inositol 1,4,5-triphosphate-induced Ca(2+) release in unfertilized mouse oocytes.

We previously demonstrated in the mouse oocyte that in vivo postovulatory aging significantly suppresses activity of the endoplasmic reticulum (ER) Ca(2+)-ATPase (Igarashi et al. 1997. Mol Reprod Dev 48:383-390). We undertook the present study to further examine the effects of oocyte aging on Ca(2+) release from the inositol 1,4,5-triphosphate (InsP(3))-sensitive Ca(2+) channels of the ER membrane, because not only Ca(2+) reuptake, but also Ca(2+) release from the ER, substantially affect Ca(2+) oscillations in fertilized oocytes. A transient increase in cytosolic free Ca(2+) concentration ([Ca(2+)](i)) was induced by photolysis of caged InsP(3) microinjected into the cytoplasm in both fresh (14 hr post hCG) and aged (20 hr or 24 hr post hCG) oocytes, where the maximum rate of increase in [Ca(2+)](i) significantly decreased in the aged oocytes. Reduced ER Ca(2+) release in the aged oocyte may not be attributable to aging-related desensitization of the InsP(3)-sensitive Ca(2+) channels in the ER because concentrations of caged InsP(3) for half maximal [Ca(2+)](i) increase were identical for fresh and aged oocytes. The peak [Ca(2+)](i) response following administration of 5 microM thapsigargin, a specific ER Ca(2+)-ATPase inhibitor, was significantly reduced in the aged oocyte, suggesting reduction of the ER Ca(2+) stores. We conclude from these results that reduction of Ca(2+) release from the InsP(3)-sensitive Ca(2+) stores in the aged oocyte arises from depletion of the ER Ca(2+) stores with aging. These aging-related changes in Ca(2+) release and reuptake may account for alterations in Ca(2+) oscillations in aged fertilized oocytes.

Adenosine Triphosphatases↗

PubMed2000

Serial changes in N-isopropyl-p[125I]-iodoamphetamine in mouse lung observed with a confocal laser scanning microscope.

Serial changes in N-isopropyl-p[125I]-iodoamphetamine (125I-IMP) in mouse lungs were observed with a confocal laser scanning microscope. Male mice were intravenously injected with 125I-IMP and subjected to autoradiographic procedures 20 minutes, and 3 and 24 hours after injection. Differential interference contrast (DIC) images and confocal images were obtained with a confocal laser scanning microscope, and superimposed images were evaluated. Large numbers of silver grains were observed in the interstitium, bronchioles, and alveolar sacs 20 minutes after the injection, and lamellar distribution of the grains was observed on the ciliary surface. The numbers of silver grains in the interstitium and bronchioles had decreased 3 hours after the injection of 125I-IMP, but the numbers of silver grains in the alveolar spaces had not. Although small numbers of silver grains remained in both the bronchioles and alveolar sacs 24 hours after the injection, most of them had washed out. Confocal laser scanning microscopy is considered to be a useful procedure for studying the distribution of radioisotopes by microautoradiography, because it allows clear autoradiographs to be obtained in which tissues and silver grains are perfectly matched and all silver grains are in focus.

Animals↗

PubMed2000

Clinical experience of Argatroban for anticoagulation in cardiovascular surgery.

PURPOSE: We have reviewed our experience with Argatroban-a direct thrombin inhibitor for anticoagulation--in a variety of cardiovascular operations, and in extracorporeal circulation, as a substitute for heparin. SUBJECTS AND METHODS: 60 patients receiving anticoagulation with Argatroban were classified into the following four groups. Group 1; 20 patients with anticoagulation therapy after cardiac surgery. Group 2; 8 patients with extracorporeal circulation for continuous hemofiltration for either pre- or post-operative control of acute renal failure. Argatroban was used alone or in combination with nafamostat mesilate. Group 3, one patient with replacement of the descending aorta with left heart assist and 15 patients with percutaneous cardiopulmonary support. And Group 4, 16 patients undergoing vascular surgery including the abdominal aorta. The target activated clotting time was individually set for each group. In Group 1, the coagulofibrinolytic activity and platelet function were measured precisely. Bleeding and complications were examined in all groups. RESULTS: Group 1; the targeted activated clotting time of 150-180 seconds was achieved by a dosage of 0.4-0.8 microgram/kg/min Argatroban. Group 2; the activated clotting time of 150-180 seconds was achieved by 0.05-1.6 micrograms/kg/min (concomitance), or by 0.02-2.5 micrograms/kg/min (alone). Group 3; the activated clotting time of 180-200 seconds by 0.05-3.86 micrograms/kg/min. And Group 4; the activated clotting time of around 150 seconds by 2.0 micrograms/kg/min with initial bolus infusion of 0.1 mg/kg. Argatroban did not promote post-surgery bleeding and had no unfavorable effect on coagulo-fibrinolysis or on platelet activity. CONCLUSION: Argatroban may be useful as an anticoagulant in the field of cardiovascular surgery as a substitute for heparin, without causing any post-surgery bleeding complication, or influencing the fibrinolytic activities or platelet functions.

Aged↗

PubMed2000

Abnormal neuronal and glial argyrophilic fibrillary structures in the brain of an aged albino cynomolgus monkey (Macaca fascicularis).

An aged albino male cynomolgus monkey (Macaca fascicularis) more than 35 years old died after showing neurological signs including gait disturbance, trembling, drowsing tendency and a decrease in activity. Neuropathological examination revealed glial fibrillary tangles (GFTs) mainly distributed in the putamen, caudate nucleus, thalamic nuclei, substantia nigra, red nucleus, globus pallidus, trapezoid body, pyramid, pons and medulla oblongata of the brain, and neurofibrillary tangles (NFTs) in the thalamic nuclei. These structures were positively stained by the modified Gallyas-Braak (GB) method and immunostained for tau. The tau-positive argyrophilic GFTs were morphologically classified into four types, as in human cases, i.e., tufts of abnormal fibers (TAFs), thornshaped astrocytes (TSAs), glial coiled bodies (GCBs) and argyrophilic threads (ATs) depending on their GB profiles, and GCBs were the major structures in this case. Some of these structures were also immunoreactive for alpha-synuclein. The glial cells possessing the structures were negative for glial fibrillary acidic protein, a marker for astrocytes, indicating that the argyrophilic GFTs were present in oligodendroglia. In addition, marked neuronal loss and ubiquitin-positive spheroid bodies were observed in the substantia nigra and globus pallidus. According to the characteristic distribution of the argyrophilic structures in neurons and glial cells as well as clinical signs, the monkey might have suffered from a neurodegenerative disease such as progressive supranuclear palsy (PSP). This is the first report of the occurrence of a neurodegenerative disease in a nonhuman animal.

Adult↗

PubMed2000

Visualization of myoglobin-facilitated mitochondrial O(2) delivery in a single isolated cardiomyocyte.

The purpose of the present study was to visualize myoglobin-facilitated oxygen delivery to mitochondria at a critical mitochondrial oxygen supply in single isolated cardiomyocytes of rats. Using the autofluorescence of mitochondrial reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H), the mitochondrial oxygen supply was imaged from approximately 1.4 microm inside the cell surface at a subcellular spatial resolution. Significant radial gradients of intracellular oxygenation were produced by superfusing the cell suspension with a mixed gas containing 2-4% oxygen while stimulating mitochondrial respiration with an uncoupler of oxidative phosphorylation. Augmentation of the NAD(P)H fluorescence started from the core of the cell (anoxic core) and progressively expanded toward the plasma membrane, as the extracellular Po(2) was lowered. Inactivation of cytosolic myoglobin by 5 mM NaNO(2) significantly enlarged such anoxic regions. Nitrite affected neither mitochondrial respiration in uncoupled cells nor the relationship between Po(2) and the NAD(P)H fluorescence in coupled cells. Thus we conclude that myoglobin significantly facilitates intracellular oxygen transport at a critical level of mitochondrial oxygen supply in single cardiomyocytes.

Animals↗

PubMed2000

Immunopathological study on the development of swine serum-induced bile duct lesions in BALB/c and DBA/2 mice.

To compare the difference in the development of swine serum (SS)-induced bile duct lesion (BDL) between high responder BALB/c and low responder DBA/2 mice, the mice of both strains injected with SS twice a week for up to 4 weeks were killed and examined immunopathologically after the 2nd, 4th, 6th and 8th SS-injection, respectively. In BALB/c mice, BDL developed rapidly following the SS-injections, and a slight enlargement of common bile ducts accompanied with infiltration of T helper cells and eosinophils was detected after the 2nd SS-injection. From the 4th injection on, BDL was characterized by proliferation of mucous glands, hyperplasia and hypertrophy of biliary and glandular epithelial cells, periductal fibrosis, infiltration of eosinophils, plasma cells and T helper cells, and increase of mast cells, resulting in more apparent enlargement of common bile ducts. Several hypertrophied biliary and glandular epithelial cells were positive for mouse immunoglobulins and SS. BDL subsided after cessation of the SS-treatment. On the other hand, in DBA/2 mice, immune response and inflammatory reaction were very weak, and only slight BDL were detected.

Animals↗

PubMed2000

Picryl chloride-induced allergic dermatitis in IQI/Jic female mice.

IQI/Jic (IQI) mice are an ICR-derived inbred strain developed in Japan, and it is known that aged females of this strain develop allergic dermatitis of spontaneous nature. In the present study, young IQI female mice which were sensitized with picryl chloride (PCL) to the shaved skin of abdomen and then topically applied with PCL to the ear at 4, 11, 18 and 25 days after the sensitization were examined. The ear swelling response increased rapidly after the 1st application, peaked after the 2nd one, and then gradually decreased. Histopathologically, edema with inflammatory cell infiltration developed after the 1st application and progressed after the 2nd one. The number of mast cells, CD4-positive cells and MHC class II-positive cells became prominent accompanied with epidermal thickening and dermal fibroplasia after the 4th application when clear elevation of total serum IgE levels was observed in many mice. Compared with the dermatitis induced in the same way in BALB/c female mice, the nature was similar with each other but the degree was obviously severer in IQI female mice. IQI female mice are considered to be a useful laboratory animal for the investigation of allergic dermatitis.

Animals↗

PubMed2000

Kinetics and distribution of transforming growth factor (TGF)-beta 1 mRNA in the dorsal skin of hypotrichotic WBN/ILA-Ht rats following topical application of T-2 toxin.

Depression of basal cell proliferating activity and subsequent induction of basal cell apoptosis in the epidermis and infiltration of inflammatory cells including mast cells in the dermis were observed in the dorsal skin of hypotrichotic WBN/ILA-Ht rats following the topical application of T-2 toxin in our previous study (ALBARENQUE et al. 1999). In the present study, kinetics of TGF-beta 1 mRNA was investigated using the same experimental system. The level of TGF-beta 1 mRNA of the whole skin tissue measured by competitive RT-PCR method showed a slight elevation from 6 to 12 hours after treatment (HAT) and reached the significantly higher level at 24HAT compared with the control skin. The increase in signals of TGF-beta 1 mRNA detected by in situ hybridization method started at 3HAT in the epidermis and progressed thereafter both in the epidermis and in the dermis. These results suggest that the elevated level of TGF-beta 1 mRNA may have a close relation to the induction of epidermal basal cell apoptosis as well as to the intradermal infiltration of mast cells and fibroblasts following the topical application of T-2 toxin.

Animals↗

PubMed2000

Ultrastructural study on the follicle-associated epithelium of nasal-associated lymphoid tissue in specific pathogen-free (SPF) and conventional environment-adapted (SPF-CV) rats.

Membranous (M) cells in follicle-associated epithelium (FAE) play an important role in the mucosal immunity through transport of a variety of foreign antigens to the underlying mucosa-associated lymphoid tissue (MALT). We aimed to investigate the ultrastructure of M cells in the FAE covering nasal-associated lymphoid tissue (NALT) both in specific pathogen-free (SPF) rats and in conventional environment-adapted (SPF-CV) rats aged 8-38 wk. In NALT of both SPF and SPF-CV rats, FAE included the nonciliated microvillous cell, which appears to be an analogue of M cell previously described in other MALT. In SPF rats, M cells increased in number only slightly with age, and they maintained morphological uniformity irrespective of age. In SPF-CV rats, M cells selectively increased in number resulting in prominent expansion of FAE surface area in parallel with the duration of maintenance in a conventional environment. In addition, M cells in SPF-CV rats showed heterogeneity in their surface morphology such as the length and number of microvilli and cell surface area and outline. In addition, the FAE was stratified by various subtypes of M cells, which were characterised by several subcellular alterations including the presence of many keratin filaments, homogeneous dark bodies and extensive cytoplasmic interfoliation with wide intercellular spaces filled with amorphous proteinaceous material. These characteristics of M cells in SPF-CV rat were intimately related with a preferential influx of immunocompetent cells into the FAE, which was not seen or was very rare in SPF rats irrespective of age. The results suggest the possibility that NALT may effectively carry out the mucosal immune response against antigenic stimuli of different magnitude through the unique dynamics of M cells which seem to be influenced by the infiltration of immunocompetent cells.

Animals↗

PubMed2000

Free vascularized bone graft for nonunion of the scaphoid.

We used a free vascularized small periosteal bone graft to treat scaphoid nonunion. The graft consisted of periosteum, full-thickness cortex, and the underlying cancellous bone and was harvested from the supracondylar region of the femur. The graft was nourished by the articular branch of the descending geniculate artery and vein. Unlike the currently used vascularized bone grafts, this graft can be easily harvested and shaped to accommodate the bone defect of the scaphoid without disturbing its vascularity and can then be transferred with microvascular anastomosis of the nutrient vessels to the radial artery and its venae commitantes. Ten patients with longstanding nonunion of the scaphoid secondary to avascular necrosis, confirmed by radiologic and intraoperative findings, were treated with this vascularized bone graft. Union was achieved in all 10 patients at an average of 12 weeks after surgery. The average follow-up period for all fractures was 3.5 years. The scores for overall outcome, according to the Mayo wrist scoring system, were excellent in 4 patients, good in 4, and fair in 2. Two unsatisfied patients had preoperative signs of early periscaphoid osteoarthrosis. This free vascularized small bone graft from the supracondylar region of the femur is an attractive alternative to the conventional vascularized bone grafting procedures.

Adolescent↗

PubMed2000

Experience with the pedicled latissimus dorsi flap for finger reconstruction.

The pedicled latissimus dorsi flap was used for the reconstruction of finger function in 12 patients with severely disabled hands. The fascial origin of the muscle was sutured directly to finger flexors in 6 patients, and to extensors in the other 6 patients in the forearm without severing the neurovascular pedicle. Voluntary contraction of the muscle was obtained in all patients. Useful tendon gliding was achieved in 6 patients, thereby providing total active motion of fingers of >100 degrees. In the remaining 6 patients, however, several problems such as stiff finger joints prevented appropriate tendon gliding, resulting in total active motion of <60 degrees. When these problems are overcome, the pedicled latissimus dorsi muscle can yield satisfactory excursion for extrinsic tendons of the fingers. In contrast to free muscle transplantation, early and predictable recovery of function can be obtained using this particular technique without any risk of denervation of the muscle.

Adolescent↗

PubMed2000

The role of the body mass index and triglyceride levels in identifying insulin-sensitive and insulin-resistant variants in Japanese non-insulin-dependent diabetic patients.

Using the minimal model approach shown by Bergman, our group had previously shown 2 variants among non-obese mildly diabetic patients, one with normal insulin sensitivity and the other with insulin resistance. The present study examines whether these 2 variants exist in the ordinary Japanese non-insulin-dependent diabetes mellitus (NIDDM) population and compares the clinical profile between the 2 discrete forms of NIDDM. In addition, we investigated the factors responsible for insulin resistance observed in Japanese NIDDM populations. One hundred eleven untreated Japanese NIDDM subjects (fasting glucose < 10 mmol/L) were assessed for insulin action (homeostasis model assessment [HOMA-IR] = fasting serum insulin (microU/mL) x fasting plasma glucose (mmol/L)/22.5) and the fasting lipid profile. Sixty percent of these patients had normal insulin sensitivity (HOMA-IR < 2.5). The insulin-resistant patients had higher serum cholesterol (188.1 +/- 5.2 v 182.2 +/- 3.9 mg/dL, P> .05) and low-density lipoprotein (LDL) cholesterol (501.2 +/- 16.7 v 469.4 +/- 14.8 mg/dL, P > .05) than the insulin-sensitive patients, but the difference was not statistically significant. In contrast, the former group had a significantly higher body mass index ([BMI] 26.6 +/- 0.8 v 21.7 +/- 0.4 kg/m2, P < .0001) and higher serum triglycerides (181.0 +/- 16.4 (range, 79 to 545) v 95.1 +/- 4.1 (range, 36 to 204) mg/dL, P < .0001) and lower high-density lipoprotein (HDL) cholesterol (47.2 +/- 1.7 v 58.2 +/- 2.5 mg/dL, P < .005) than the latter group. HOMA-IR was related to the BMI. Fifteen of 17 (88%) NIDDM patients with a BMI greater than 27.0 were insulin-resistant, whereas 35 of 38 (92%) NIDDM patients with a BMI less than 21.5 were insulin-sensitive. In the midrange BMI (21.5 to 27.0 kg/m2), patients were equally likely to be insulin-resistant or insulin-sensitive. Analysis of the midrange BMI group showed that HOMA-IR was associated with serum triglycerides (P < .0001) but not with the BMI. These data suggest the following conclusions: (1) Japanese NIDDM patients can be classified into 2 populations, one with normal insulin sensitivity and the other with insulin resistance; (2) NIDDM patients with normal insulin action have a low cardiovascular disease risk factor, whereas those with insulin resistance have a markedly increased cardiovascular disease risk factor; and (3) the BMI and serum triglyceride level per se are associated with insulin action in Japanese NIDDM populations.

Adult↗

PubMed2000

The diagnostic value of intraoperative measurement of choline acetyltransferase activity during brachial plexus surgery.

We used the measurement of choline acetyltransferase (CAT) activity to distinguish between preganglionic and postganglionic injuries of the spinal roots during brachial plexus surgery. This study includes ten spinal roots in six patients with traumatic brachial plexus injuries. The results of CAT activity were compared with myelographic findings, the operative findings and the intraoperative evoked spinal cord potentials. The results of CAT activity and the operative findings were consistent in all roots. Whereas CAT activity in fascicles in preganglionic injured roots was below 500 cpm, it was above 2000 cpm in postganglionic injured roots. This study shows that intraoperative measurement of CAT activity can provide useful information on the site and severity of brachial plexus injuries and the assessment of the motor function status of the injured spinal root, both directly and quantitatively.

Adult↗

PubMed2000

Reconstruction of hip abduction using free muscle transplantation: a case report and description of the technique.

The authors describe a free-functioning latissimus dorsi muscle transplantation for reconstruction of hip abduction. A radical "buttockectomy" was performed on a 62-year-old patient with recurrent soft-tissue sarcoma. The patient received a muscle transplantation immediately after resection of the tumor. Until recovery of the muscle, a complete absence of hip abductors resulted in a marked lurch in the patient's gait, requiring him to use walking aids. Reinnervation of the muscle was confirmed via electromyography 6 months after surgery. Hip abduction was restored along with muscle recovery, and walking support was no longer required. Although the strength of the muscle was not sufficiently powerful to overcome gravity fully, the latissimus dorsi muscle improved markedly the performance of an otherwise unstable hip. This patient demonstrates that microsurgical reconstruction is of great value in enhancing the functional outcome of a salvaged limb after tumor surgery.

Biomechanical Phenomena↗