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Biomedical subjects

N Yoshimura

Publications and source records attributed to N Yoshimura.

At least 217 records · Page 12Linked to original sources
PubMed1998

[Pulmonary edema due to acute airway obstruction immediately after tracheal extubation].

A 33-year-old male was scheduled for tonsillectomy and pharyngoplasty due to sleep apnea syndrome. The intubation was uneventful following induction with thiamylal and vecuronium. Anesthesia was maintained with O2-N2O-sevoflurane. No complications were observed during the 90 min operation. After the termination of the anesthesia, a hyperadrenergic state was observed: arterial pressure and heart rate rose to 230/135 mmHg and 135 bpm, respectively. Immediately after extubation, he developed dyspnea with tracheal tag and stridor, and became cyanotic despite the use of a simple oxygen mask and assisted ventilation. Laryngospasm was suspected. The patient was reintubated and suctioned; pink, frothy sputum was not obtained. Arterial blood gases 5 minutes after reintubation revealed a pH of 7.24, Pao2 86 mmHg (FIo2 1.0), and Paco2 54 mmHg. Chest X-ray 30 minutes after reintubation revealed bilateral diffuse alveolar infiltration. The diagnosis was interstitial pulmonary edema. The patient was ventilated mechanically by applying a positive end-expiratory pressure of 5cm H2O, and furosemide and dopamine were administered intravenously. The patient was extubated the next day, and discharged from hospital ten days later. We considered that the lung edema was induced by the severe negative pressure generated by inspirating against a closed upper airway, as well as by the hyperadrenergic state and severe hypoxemia observed during and after extubation.

Acute Disease↗
PubMed1998

[Difference between transcortical sensory aphasia following the left frontal lesion and transcortical sensory aphasia following the left posterior lesion].

We assessed the difference between transcortical sensory aphasia (TCSA) following the left frontal lesions (F-TCSA) and TCSA following the left posterior lesions (P-TCSA). All the patients were right-handed and the 7 patients had the lesions in the only frontal lobe and the 10 patients had the lesions only in the left temporo-parieto-occipital regions. We administered pointing tasks, using 90 line drawings representing single nouns. We presented 6 line drawings a pointing board, and we used two kinds of pointing boards: one showed the line drawings each belonging to different categories (random categorized pointing task), the other showed the line drawings each belonging to only either two different categories (two categorized pointing task) and we presented 15 pointing boards each alternatively. The result was that regarding the patients of P-TCSA showed different number of correct answers between the random categorized pointing task and the two categorized pointing task with statistical significance. Regarding the patients of F-TCSA showed no difference between them. The results indicated that disturbance of P-TCSA on the pointing task was the disturbance of semantic process per se. And the disturbance of F-TCSA on the pointing task was that of not only semantic process but also the whole process including comprehending the presented words, searching the line drawings, comparing the line drawings with the presented word and final selection, which demanded persistent multiple memory process consistent with working memory.

Aphasia, Wernicke↗
PubMed1997

Plasticity of Na+ channels in afferent neurones innervating rat urinary bladder following spinal cord injury.

1. Whole-cell patch-clamp recordings in combination with axonal tracing techniques were used to investigate the effects of chronic spinal cord injury on the electrical properties of dorsal root ganglion neurones innervating the urinary bladder or colon of the adult rat. 2. In spinal intact animals, the majority (73-74%) of bladder and colon neurones which were small in size exhibited high-threshold humped spikes mediated by tetrodotoxin (TTX)-resistant Na+ channels, whereas large neurones had low-threshold narrow spikes mediated by TTX-sensitive Na+ channels. 3. In chronic spinal transected animals, 60% of bladder afferent neurones exhibited TTX-sensitive low-threshold spikes. The average diameter and input capacitance of the cells were significantly larger than those of cells obtained from spinal intact animals. 4. In bladder afferent neurones from chronic spinal transected rats, the density of TTX-resistant Na+ currents significantly decreased from 60.5 to 17.9 pA pF-1, whereas that of TTX-sensitive currents increased from 32.1 to 80.6 pA pF-1. 5. These changes in action potential and Na+ current characteristics were not detected in colon afferent neurones following spinal cord injury. 6. The results indicate that spinal cord injury increases bladder afferent neurone excitability by shifting the expression of Na+ channels from a high-threshold TTX-resistant type to a low-threshold TTX-sensitive type. This change in properties may occur in response to alterations in neurotrophic signals originating in the hypertrophied bladder.

Action Potentials↗
PubMed1997

A novel gene suppressed in the ventricle of carnitine-deficient juvenile visceral steatosis mice.

In order to clarify the pathogenesis and pathophysiology of cardiac hypertrophy in carnitine-deficient juvenile visceral steatosis (JVS) mice, we performed mRNA differential display analysis with total RNA extracted from the ventricles of control and JVS mice at 14 days of age. We identified four up-regulated genes, two known and two unknown, and a novel down-regulated gene. Northern blot analysis with a novel cDNA probe derived from the down-regulated gene fragment 8A2 revealed three mRNA species of 1.1-, 1.3-, and 2.6-kb. The 1.1- and 1.3-kb mRNA species were found only in the heart, and the 2.6-kb species was found in the heart, kidney and brain, but not in skeletal muscle or liver. The 1.1- and 1.3-kb species were down-regulated in the ventricles of JVS mice, but not in the auricles, and increased to the control level with carnitine treatment. We isolated cDNA clones from ventricle RNA, termed CDV-1 (carnitine deficiency-associated gene expressed in ventricle) and from brain RNA, termed CDV-1R (CDV-1-related gene) by 5'- and 3'-RACE analyses. The entire nucleotide sequence except the 5'-terminal 64 bp of CDV-1 cDNA was completely identical to the 992 bp sequence from the 3'-end of CDV-1R cDNA. The CDV-1 cDNA contained an open reading frame predicting a peptide of 107 amino acids, which composed the C-terminal portion of CDV-1R peptide consisting of 414 amino acids.

Amino Acid Sequence↗
PubMed1997

The central neural pathways involved in micturition in the neonatal rat as revealed by the injection of pseudorabies virus into the urinary bladder.

Pseudorabies virus was injected into the wall of the urinary bladder in 2- and 12-day-old rats in order to examine developmental changes in the central neural pathways controlling micturition. Forty-eight hours after virus injection, virus-labeled neurons were identified in the lumbosacral spinal cord but not in the brain. Sixty to seventy-two hours after virus injection in both 2- and 12-day-old rats, infected neurons were detected in Barrington's nucleus, nucleus paragigantocellularis, nucleus reticularis gigantocellularis, A5 area, nucleus raphe obscurus, locus subcoeruleus, periaquaductal gray, red nucleus, paraventricular nucleus and cerebral cortex. These results in neonatal rats are similar to those reported in adult rats. Thus, it is likely that the supraspinal neural circuitry which underlies micturition in the adult animal is already organized in the neonatal rat during the early postnatal period even though the supraspinal micturition reflex pathway does not become functional until the third postnatal week.

Aging↗
PubMed1997

Electron microscopic immunohistochemistry of ocular and extraocular pseudoexfoliative material.

To investigate the nature of extraocular pseudoexfoliative (PSX) material, and to validate the hypothesis that the PSX syndrome is a systemic disorder, we studied the immunoreactivity of intraocular and extraocular PSX material from patients with the PSX syndrome using antibodies against proteins of extracellular matrices. Surgical specimens of four different tissues were obtained from human eyes with the PSX syndrome: nine trabecular tissues, three cataractous lenses, six bulbar conjunctivas, and seven lid skins. These tissues were processed for electron microscopic immunohistochemistry, and stained with antibodies against vitronectin, fibronectin, laminin, and elastin, by an indirect immunogold procedure. Density of the gold particles located on the PSX material was estimated by video image analysis. Statistical analysis of the data revealed that the PSX material from trabecular tissues, lenses, bulbar conjunctivas, and lid skins had almost identical immunoreactivity to the antibodies studied. PSX materials of trabecular tissues, lenses, bulbar conjunctivas, and lid skins were found to have not only a similar ultrastructure, but also almost identical immunohistochemical characteristics. These results support the hypothesis that the PSX syndrome is a systemic disorder.

Aged↗
PubMed1997

Diagnosis of intraocular lymphoma by polymerase chain reaction.

BACKGROUND: Cytopathological examinations have been used in the diagnosis of intraocular lymphoma. However, sometimes it is not easy to detect malignant cells in the biopsy specimens. We applied a method that identified monoclonal proliferation of B lymphocytes by using polymerase chain reaction (PCR) in the diagnosis of patients suspected to have intraocular B-cell lymphoma. METHODS: Three specimens of the diagnostic vitrectomy were studied by cytological examination and by PCR to amplify the complementary determining region (CDR3) of immunoglobulin heavy chain (IgH) gene. As a positive control, a biopsy specimen of an orbital lymphoma was examined; four vitrectomy specimens from patients with diabetic retinopathy, proliferative vitreo-retinopathy, acute retinal necrosis (ARN) and macular hole were negative controls. RESULTS: On cytologic examination, no malignant cells were found in three specimens: suspected intraocular lymphoma and one ARN. In contrast, a discrete band that reflected monoclonal proliferation of B lymphocytes was detected by PCR in specimens from two patients and the positive control. Vitrectomy specimens from the negative controls, including ARN, did not show a discrete band on PCR. CONCLUSIONS: Two cases of ocular malignant lymphoma were diagnosed by PCR identification of monoclonal proliferation of B lymphocytes. This method may be an additional diagnostic tool in the diagnosis of intraocular B-cell lymphoma.

Aged↗
PubMed1997

Open distal anastomosis in retrograde cerebral perfusion for repair of ascending aortic dissection.

BACKGROUND: In patients with aortic dissection, a patent distal false lumen at long-term follow-up leads to complications. We investigated the feasibility of performing an open distal anastomosis using retrograde cerebral perfusion. METHODS: Over a 10-year period, 41 patients with acute type A aortic dissection underwent 43 surgical repairs. In 1991, an open distal anastomosis using retrograde cerebral perfusion (group 2) was introduced to replace the standard aortic cross-clamp method (group 1). The mean retrograde cerebral perfusion time was 47.3 minutes (range, 22 to 67 minutes), and there were no neurologic sequelae in surviving patients. RESULTS: The operative mortality rate was 18.5% in group 1 and 18.7% in group 2. At long-term follow-up, dilatation of the false lumen (more than 50 mm in diameter) occurred in 9 of 18 patients (50%) in group 1, and 2 patients died of aortic rupture. There were no deaths in group 2, and dilatation of the distal false lumen occurred in only 15.4% of patients (p < 0.05). CONCLUSIONS: The use of retrograde cerebral perfusion in patients with acute aortic dissection provides adequate time to perform a safe, open, distal anastomosis, and could decrease significantly the rate of enlarged, patent, false lumina.

Acute Disease↗
PubMed1997

Diabetic cystopathy: relationship to autonomic neuropathy detected by sympathetic skin response.

PURPOSE: The possible relationship between bladder dysfunction and autonomic neuropathy was investigated in unselected diabetic patients. MATERIALS AND METHODS: Bladder function was examined by cystometry in 53 unselected diabetic patients and 10 healthy controls. Sympathetic skin response was recorded in 23 of 53 patients and all control subjects to evaluate autonomic neuropathy associated with diabetes, and the results were compared to cystometric findings. RESULTS: Cystometrograms exhibited significant increases in bladder volume at first desire to void and maximal bladder capacity, and a decrease in detrusor contractility in diabetic patients compared to those in controls. In addition, mean residual urine was significantly larger in diabetic patients than in controls. Among the 53 diabetic patients these bladder dysfunctions were also found in each subset of patients with no sign of retinopathy (33), no subjective urinary symptoms (32) or duration of diabetes less than 1 year (12). In 23 patients in whom sympathetic skin response was measured 12 without sympathetic skin responses had increased residual urine and decreased detrusor contraction pressure. The remaining 11 patients with a lower amplitude of sympathetic skin response and more prolonged latency than controls had a significant decrease in detrusor contraction pressure. CONCLUSIONS: Bladder dysfunction, characterized by loss of sensation, increased capacity and decreased contractility, was the main observation of diabetic cystopathy regardless of the duration or severity of the disease. The association of bladder dysfunction and autonomic neuropathy detected by the sympathetic skin response might indicate that diabetic cystopathy is a manifestation of peripheral neuropathy induced by diabetes.

Adult↗
PubMed1997

Initial MRI findings of non-traumatic osteonecrosis of the femoral head in renal allograft recipients.

Fifty-one renal allograft recipients (15-62 years old, mean: 37 years) were monitored for 2.5-6.5 years (average: 4.3 years) after surgery by using magnetic resonance imaging (MRI) to find (i) initial signs of osteonecrosis of the femoral head (ONF), (ii) the presence of bone marrow edema as an initial sign of ONF, (iii) any changes of MRI patterns, and (iv) the relationship between these MRI findings and prognosis. MRI was performed preoperatively (baseline), and whenever possible during the 6-9th week, 12-16th week, 12th month, and yearly thereafter. T1- and T2-weighted images were obtained by using a spin echo technique. Abnormalities were first detected on MRI of 23 femoral heads in 13 patients between 6 weeks and 12 months. All lesions first showed a low intensity band on T1-weighted images and a high intensity band on T2-weighted images. No symptoms or diffuse patterns, such as bone marrow edema, preceded the appearance of the band pattern. After the 12th month, no new abnormal findings on MRI were detected. The lesions were classified into Type A, B, or C, according to the location. 12 of the 16 Type C femoral head lesions, which extend beyond the medial two thirds of the weight-bearing portion of the acetabulum, became symptomatic 7-14 months after transplantation and then progressed to collapse. Bone marrow edema appeared with radiological collapse and symptoms. With the exception of five lesions in three patients who failed to be MR imaged until 12 months postoperatively, all lesions were first detected on MRI within 16 weeks after transplantation. We therefore postulate that the ischemic event that causes ONF will have occurred within 12 weeks after transplantation, considering the time lag of reparative reaction to the dead bone.

Adolescent↗
PubMed1997

Case-control study of risk factors for hip fractures in the Japanese elderly by a Mediterranean Osteoporosis Study (MEDOS) questionnaire.

A case-control study of hip fracture among the Japanese elderly was carried out in order to assess the risk factors for fractures. On the data obtained from 249 cases and 498 controls matched with ethnicity, sex, age, and residential area, significant risk factors on the lifestyle by multivariate analyses included drinking more than three cups of coffee daily, living in rural areas in the past, sleep disturbance, stroke with hemiplegia, and sleeping in a (Western-type) bed. In contrast, in addition to possession of a large body mass index, moderate alcohol intake and eating fish appeared to be associated with a reduced risk of hip fracture. In conclusion, some traditional Japanese lifestyle characteristics may prevent hip fractures among the Japanese elderly.

Aged↗
PubMed1997

Possible mechanisms underlying the midazolam-induced relaxation of the noradrenaline-contraction in rabbit mesenteric resistance artery.

1. The mechanisms underlying the midazolam-induced relaxation of the noradrenaline (NA)-contraction were studied by measuring membrane potential, isometric force and intracellular concentration of Ca2+ ([Ca2+]i) in endothelium-denuded muscle strips from the rabbit mesenteric resistance artery. The actions of midazolam were compared with those of nicardipine, an L-type Ca2+-channel blocker. 2. Midazolam (30 and 100 microM) did not modify either the resting membrane potential or the membrane depolarization induced by 10 microM NA. 3. NA (10 microM) produced a phasic, followed by a tonic increase in both [Ca2+]i and force. Midazolam (10-100 microM) did not modify the resting [Ca2+]i, but attenuated the NA-induced phasic and tonic increases in [Ca2+]i and force, in a concentration-dependent manner. In contrast, nicardipine (0.3 microM) attenuated the NA-induced tonic, but not phasic, increases in [Ca2+]i and force. 4. In Ca2+-free solution containing 2 mM EGTA, NA (10 microM) transiently increased [Ca2+]i and force. Midazolam (10-100 microM), but not nicardipine (0.3 microM), attenuated this NA-induced increase in [Ca2+]i and force, in a concentration-dependent manner. However, midazolam (10 and 30 microM), had no effect on the increases in [Ca2+]i and force induced by 10 mM caffeine. 5. In ryanodine-treated strips, which have functionally lost the NA-sensitive Ca2+ storage sites, NA slowly increased [Ca2+]i and force. Nicardipine (0.3 microM) did not modify the resting [Ca2+]i but partly attenuated the NA-induced increases in [Ca2+]i and force. In the presence of nicardipine, midazolam (100 microM) lowered the resting [Ca2+]i and further attenuated the remaining NA-induced increases in [Ca2+]i and force. 6. The [Ca2+]i-force relationship was obtained in ryanodine-treated strips by the application of ascending concentrations of Ca2+ (0.16-2.6 mM) in Ca2+-free solution containing 100 mM K+. NA (10 microM) shifted the [Ca2+]i-force relationship to the left and enhanced the maximum Ca2+-induced force. Under these conditions, whether in the presence or absence of 10 microM NA, midazolam (10 and 30 microM) attenuated the increases in [Ca2+]i and force induced by Ca2+ without changing the [Ca2+]i-force relationship. 7. It was concluded that, in smooth muscle of the rabbit mesenteric resistance artery, midazolam inhibits the NA-induced contraction through its inhibitory action on NA-induced Ca2+ mobilization. Midazolam attenuates NA-induced Ca2+ influx via its inhibition of both nicardipine-sensitive and -insensitive pathways. Furthermore, midazolam attenuates the NA-induced release of Ca2+ from the storage sites. This effect contributes to the midazolam-induced inhibition of the NA-induced phasic contraction.

Animals↗
PubMed1997

Tranilast inhibits the proliferation, chemotaxis and tube formation of human microvascular endothelial cells in vitro and angiogenesis in vivo.

1. First developed as an antiallergic drug, tranilast inhibits chemical mediator release from mast cells. In the present study, we examine the effects of tranilast on angiogenesis in vitro and in vivo and discuss the application of tranilast for angiogenic diseases. 2. Tranilast inhibited significantly the proliferation (IC50: 136 microM, 95% confidence limits: 134-137 microM) and vascular endothelium growth factor (VEGF)-induced chemotaxis (IC50: 135 microM, 95% confidence limits: 124-147 microM) of human dermal microvascular endothelial cells (HDMECs) at concentrations greater than 25 micrograms ml-1. No toxicity to HDMECs measuring by LDH release and no inhibitory effects on metalloproteinase (MMP)-2 and MMP-9 activity were observed even at 100 micrograms ml-1 (306 microM). 3. Tube formation of HDMECs cultured on the matrigel as an in vitro angiogenesis model was inhibited by tranilast in a concentration-dependent manner. The IC50 value and 95% confidence limits were 175 microM and 151-204 microM, respectively. 4. In vivo angiogenesis was induced in mice by the subcutaneous injection of matrigel containing 30 ng ml-1 VEGF and 64 micrograms ml-1 heparin. Tranilast was administered orally twice a day for 3 days. Tranilast dose-dependently suppressed angiogenesis in the matrigel and a significant change was observed at a dose of 300 mg kg-1. 5. These results indicate that tranilast is an angiogenesis inhibitor which may be beneficial for the improvement of angiogenic diseases such as proliferative diabetic retinopathy, age-related macular degeneration, tumour invasion and rheumatoid arthritis.

Animals↗
PubMed1997

Expression of neurotrophic factors in cultured human retinal pigment epithelial cells.

PURPOSE: To see if cultured human retinal pigment epithelial (RPE) cells have the capacity to synthesize neurotrophins, including nerve growth factor (NGF), brain-derived growth factor (BDNF), and neurotrophin-3 (NT-3). METHODS: Expression of mRNAs for the neurotrophins was studied by the reverse transcription polymerase chain reaction (PCR) method. Quantitative analysis of the gene expression was done by using a semiquantitative PCR method. Secretion of NGF-like immunoreactivity (NGF-LI) into the culture medium was analyzed by enzyme immunoassay (EIA). RESULTS: Cultured human RPE cells were found to express mRNAs for NGF, BDNF and NT-3. In the conditioned culture medium of the human RPE, 9.44 +/- 0.62 pg/ml (mean +/- SEM, n = 6) NGF-LI was found. Pretreatment of human RPE cells with interleukin-l (IL-1) (20 ng/ml), phorbol myristate acetate (PMA) (100 ng/ml) or tumor necrosis factor-alpha (TNF-alpha) (40 ng/ml) was found to increase the mRNA expression of neurotrophins and also to increase secretion of NGF-LI into the culture medium. CONCLUSIONS: Our data demonstrate that cultured human RPE cells have the capacity to synthesize neurotrophins, and that various stimulations can up-regulate gene and protein expression of NGF by these cells.

Brain-Derived Neurotrophic Factor↗
PubMed1997

Abnormal naive and memory T lymphocyte subsets in the peripheral blood of patients with uveitis.

PURPOSE: To better define the role of lymphocytes in the pathogenesis of uveitis, we studied the expression of memory and naive cell markers on T lymphocytes from peripheral blood. METHODS: Surface antigens on T lymphocytes obtained from peripheral blood of 27 patients with uveitis, including 12 patients with Behçet's disease (BD), 7 patients with Vogt-Koyanagi-Harada disease (VKH), and 8 patients with idiopathic uveitis (IU), were detected by three-color flow cytometric analysis. Lymphocytes from 14 age-matched healthy control subjects were similarly evaluated. RESULTS: The percentage of T lymphocytes that were CD4+CD29+ lymphocytes (memory cells) was high in all patients with uveitis, while that of CD4+CD45RA+ lymphocytes (naive cells) was lower in patients with BD and VKH, although the difference was not statistically significant. The percentage of CD29+ cells within CD3+CD4+ cell population was significantly higher in patients with BD and VKH than in the controls (p < 0.01), and the percentage of CD45RA+ cells was significantly lower in BD patients than in controls (p < 0.01). The T lymphocyte subsets in patients with IU were similar to the controls. CONCLUSIONS: These results show an abnormal distribution of T lymphocytes in patients with uveitis associated with an underlying systemic disease.

Adult↗