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Biomedical subjects

K Machii

Publications and source records attributed to K Machii.

At least 19 recordsLinked to original sources
PubMed1998

Physiological analyses of a patient with extreme widening of Virchow-Robin spaces.

We report on a 60-year-old woman with extreme widening of Virchow-Robin spaces who showed neither neurological symptoms nor signs. Magnetic resonance imagings (MRIs) of her brain disclosed multiple abnormalities located along the perforating medullary arteries in the white matter. Central sensory and motor conduction studies (sensory evoked potentials (SEPs) and magnetic stimulation) showed no conduction delays and several modulatory inputs normally influenced the motor and sensory cortical excitability, as expected from clinical features. These physiological analyses confirmed the functional integrity of the central sensory and motor systems, even though imaging studies showed seemingly serious abnormalities.

Brain↗
PubMed1998

Paired-pulse magnetic stimulation of the human motor cortex: differences among I waves.

1. In paired-pulse cortical stimulation experiments, conditioning subthreshold stimuli suppress the electromyographic (EMG) responses of relaxed muscles to suprathreshold magnetic test stimuli at short interstimulus intervals (ISIs) (1-5 ms) and facilitate them at long ISIs (8-15 ms). 2. We made paired-pulse magnetic stimulation studies on the response of the first dorsal interosseous muscle (FDI) produced by I1 or I3 waves using our previously reported method which preferentially elicits one group of I waves when subjects make a slight voluntary contraction. In some experiments the conditioning and test stimuli were oppositely directed, in the others they were oriented in the same direction. Single motor unit responses were recorded with a concentric needle electrode, and surface EMG responses with cup electrodes. 3. In post-stimulus time histograms (PSTHs) of the firing probability of motor units, the peaks produced by I3 waves were decreased by a subthreshold conditioning stimulus that preferentially elicited I1 or I3 waves at an ISI of 4 ms. The amount of decrement depended on the intensity of the conditioning stimulus. The stronger the conditioning stimulus, the greater the suppression. In contrast, the peaks produced by I1 waves were little affected by any type of subthreshold conditioning stimulus, given 4 ms prior to the test stimulus. At an ISI of 10 ms, a subthreshold conditioning stimulus slightly decreased the size of the peak produced by the I3 waves, but did not affect the peaks evoked by I1 waves. 4. Surface EMGs showed that a subthreshold conditioning stimulus suppressed the responses produced by I3 waves irrespective of its current direction (anterior or posterior). Both the amount and duration of suppression depended on the intensity of the conditioning stimulus, but not on its current direction. Both parameters increased when the intensity increased. At a high intensity conditioning stimulus, suppression was evoked at ISIs of 1-20 ms, compatible with the duration of GABA-mediated inhibition found in animal experiments. Responses produced by I1 waves were little affected by any type of subthreshold conditioning stimulus. 5. We conclude that a subthreshold conditioning stimulus given over the motor cortex moderately suppresses I3 waves but does not affect I1 waves. The duration of suppression of the I3 waves supports the idea that this is an effect of GABAergic inhibition within the motor cortex.

Adult↗
PubMed1998

MHV-induced fatal peritonitis in mice lacking IFN-gamma.

IFN-gamma gene was disrupted by homologous recombination in A3-1 embryonic stem cells. Germinally transmitted chimeric mice were successfully obtained and backcrossed with C57BL/6 (B6) mice 5 or 6 times. Deficiency of IFN-gamma in homozygous mice was confirmed by northern blot analysis of spleen cells stimulated with phorbor esther and calcium ionophore and also by IFN-gamma production in the culture supernatant of spleen cells stimulated with the same reagents. B6 mice lacking IFN-gamma were infected intraperitoneally (ip) with 10(6) PFU of JHMV and monitored for their survival. Approximately 90% of the mice died at 50 days post-infection (pi) and the mean survival time was 28 days. Mice sacrificed at 3 weeks pi showed severe peritonitis accompanying the accumulation of a viscous fluid in the abdominal and thoracic cavities. Microscopically, the disease was characterized by disseminated granulomatous inflammation and exudative fibrinous serositis in the abdominal cavity. Infectious virus was isolated in most tissues including the liver, spleen, kidney, pancreas and lung during the experimental periods. The disease was not observed in wild-type or heterozygous littermates infected i.p. with JHMV. These results suggest that IFN-gamma plays a critical role in MHV infection in mice. This experimental model may provide a unique opportunity to address the pathogenesis of virus-induced peritonitis such as feline infectious peritonitis in cats.

Acute Disease↗
PubMed1998

Cortico-cortical inhibition of the motor cortical area projecting to sternocleidomastoid muscle in normals and patients with spasmodic torticollis or essential tremor.

OBJECTIVES: To investigate whether the cortico-cortical inhibition originally reported for the human hand motor area is present in the motor cortex for sternocleidomastoid muscle (SCM) and to evaluate the amount of inhibition in spasmodic torticollis and essential tremor. METHODS: Subjects were 14 normal healthy volunteers, 10 patients with spasmodic torticollis and 5 with essential tremor involving neck muscles. A paired-pulse magnetic stimulation was performed for the SCMs and first dorsal interosseous muscles (FDIs). RESULTS: In normal subjects, a subthreshold magnetic conditioning stimulus suppressed responses to a suprathreshold magnetic test stimulus when their interval was 1-5 ms in SCM. This indicates that the similar cortico-cortical inhibitory mechanism is present in the motor cortex for SCM as in the hand motor area. In the patients with spasmodic torticollis, the cortico-cortical inhibitory effect was reduced or absent in SCM, but normal in the FDI. In contrast, in patients with essential tremor, normal cortico-cortical inhibition was seen in both the SCM and FDI. CONCLUSIONS: The cortico-cortical inhibitory mechanisms of the motor cortex for SCM can be studied by a paired-pulse magnetic stimulation method. Our result of reduced cortico-cortical inhibition in torticollis patients suggests abnormal excitability (hyperexcitable or disinhibited) of the motor cortex for SCM in spasmodic torticollis.

Adult↗
PubMed1998

Murine coronavirus-induced subacute fatal peritonitis in C57BL/6 mice deficient in gamma interferon.

Gamma interferon-deficient (IFN-gamma-/-) mice with a C57BL/6 background were infected intraperitoneally with mouse hepatitis virus strain JHM (JHMV). In contrast to IFN-gamma-+/- and IFN-gamma+/+ mice, JHMV persisted in IFN-gamma-/- mice and induced death during the subacute phase of the infection. Unexpectedly, infected IFN-gamma-/- mice showed severe peritonitis accompanying the accumulation of a viscous fluid in the abdominal and thoracic cavities in the subacute phase. Destructive changes of hepatocytes were not observed. Administration of recombinant IFN-gamma protracted the survival time of IFN-gamma-/- mice after JHMV infection. These results demonstrate that IFN-gamma plays a critical role in viral clearance in JHMV infection. They also show that a resultant persistent JHMV infection induces another form of disease in IFN-gamma-/- mice, which bears a resemblance to feline infectious peritonitis in cats.

Alanine Transaminase↗
PubMed1997

Magnetic stimulation over the cerebellum in patients with ataxia.

We studied 20 patients with ataxia caused by various disorders using magnetic stimulation over the cerebellum. Results were compared with normal values found for 12 normal volunteers. In normal subjects, a magnetic stimulus over the cerebellum reduced the size of responses evoked by magnetic cortical stimulation when it preceded cortical stimulus by 5, 6 and 7 ms. The grand average of the ratios of the areas of conditioned responses at intervals of 5, 6 and 7 ms to those of control responses was designated the average area ratio (5-7 ms). Suppression of motor cortical excitability was reduced or absent in patients with a lesion in the cerebellum or cerebellothalamocortical pathway, but was normal in patients with a lesion in the afferent pathway to the cerebellum. Normal suppression was observed in Fisher's syndrome. The average area ratio (5-7 ms) correlated well with the severity of ataxia in patients with degenerative late-onset ataxia. These results are consistent with those for electrical stimulation of the cerebellum reported previously. We conclude that magnetic stimulation over the cerebellum produces the same effect as electrical stimulation even in ataxic patients. This less painful method can be used clinically to clarify the pathomechanisms for ataxia. Two other clinical uses of this technique were that it revealed clinically undetectable cerebellar dysfunction in patients whose extrapyramidal signs masked cerebellar signs, and that the slow progression of ataxia could be followed quantitatively in patients with degenerative late-onset ataxia.

Adult↗
PubMed1996

Maintenance of pluripotency in mouse embryonic stem cells persistently infected with murine coronavirus.

A persistently coronavirus-infected embryonic stem (ES) cell line A3/MHV was established by infecting an ES cell line, A3-1, with mouse hepatitis virus type-2. Although almost all A3/MHV cells were found infected, both A3/MHV and A3-1 cells expressed comparable levels of cell surface differentiation markers. In addition, A3/MHV cells retained the ability to form embryoid bodies. These results suggest that persistent coronavirus infection does not affect the differentiation of ES cells.

Animals↗
PubMed1996

Characterization of T cells expanded in vivo during primary mouse hepatitis virus infection in mice.

After intraperitoneal infection with mouse hepatitis virus, strain JHM (JHMV), JHMV replicated in the spleen of C57BL/6 mice for a few days but cleared within a week. The acute viral clearance coincided with moderate expansion of CD8+T cells and modest expansion of CD4+T cells, and was impaired moderately in mice depleted of CD8+T cells and completely in mice depleted of both CD4+ and CD8+T cell subsets. Flow cytometric analysis showed that expression of cell surface markers on the spleen T cells changed during JHMV infection. CD8+T cells expressing increased amounts of CD11a, CD43, CD44 and CD49d, and those expressing decreased levels of T cell receptor alpha beta, CD8, CD45RB and L-selectin were expanded in the spleen after JHMV infection. However, they did not express CD11b, CD25 or NK1.1. They used highly heterogenous V beta chains for their T cell receptors. In addition to CD11ahighCD8+T cells, CD11ahighCD4+T cells were detected transiently after JHMV infection. The virus-specific cytotoxic T lymphocyte (CTL) activity was observed in both CD4+ and CD8+ spleen T cells from mice 7 days post-infection. The present study shows the dynamics of CD8+ and CD4+T cells in the spleen during JHMV infection in mice and suggests that CD11ahighT cells may be involved in JHMV clearance in vivo because their appearance was temporally correlated with T cell-mediated viral clearance in vivo and antiviral CTL activity in vitro.

Animals↗
PubMed1996

Generation of antiviral CD11ahigh T cells in CD4+ T cell-depleted mice and adult thymectomized mice after mouse hepatitis virus infection.

The mechanism of CD11ahighCD8+ T cell induction after mouse hepatitis virus infection, which has been suggested to play a key role in the elimination of infectious virus from the spleen in C57BL/6 mice, was studied. In CD4+ T cell-depleted mice, CD11ahighCD8+ T cells were induced in the spleen and spleen cells showed virus-specific cytotoxic T lymphocyte activity after mouse hepatitis virus infection. The same results were obtained in adult thymectomized mice. These results indicate that CD11ahighCD8+ T cells can be generated after mouse hepatitis virus infection in the absence of either CD4+ T cells or the thymus.

Aging↗
PubMed1996

Role of CD4+ and CD8+ T cells in mouse hepatitis virus infection in mice.

Viral growth and histopathological changes in the liver after intraperitoneal infection with mouse hepatitis virus, strain JHM were compared among normal C57BL/6 mice, those depleted of CD4+ T cells, CD8+ T cells and both T cell subsets. Viral growth in mice depleted of CD4+ T cells increased slightly, but pathological changes resembled those in normal mice. In contrast, the hepatitis was exacerbated in mice depleted of CD8+ T cells and those depleted of both T cell subsets. These results suggest that CD8+ T cells play a key role although both T cell subsets are involved in protection against mouse hepatitis virus infection in mice.

Animals↗
PubMed1995

[A case report of pyomyositis--early diagnosis and follow-up by MRI].

We report a rare case of pyomyositis in a 28-year-old Japanese woman who was not immunocompromised. She was admitted because of high fever, sore throat, and severe tenderness and swelling of the right calf. Redness, swelling, and tenderness indicated presence of acute inflammation in the calf. CT of the lower extremities demonstrated low density areas in the right soleus muscle and surrounding fascia with marked swelling, which were of high signal on T2 weighted images of MRI. There was no finding of abscess formation. A tentative clinical diagnosis of acute pyomyositis was made, and antibiotics therapy with a combination of fosfomycin and sulbactam/cefoperazone was started although the arterial blood culture was negative for bacteria. Associated acute tonsilitis was the most probable focus of pyomyositis. Antibiotics relieved her symptoms, and the inflammation subsided in several weeks. No surgical procedure was necessary. MRI taken tree weeks after the onset demonstrated abscess formation between the soleus and gastrocnemius muscles. Slight high intensity indicating scar formation remained in the area of the former abscess six weeks after the onset. MRI was very useful not only in making the early diagnosis but also in the follow-up of pyomyositis.

Adult↗
PubMed1994

[123I-IMP SPECT findings of visual perseveration in a patient with old hemorrhage in the right occipital lobe].

We report a case of visual presevertation in a 67-year-old man. He had been well until 66 years of age when he had brain hemorrhage in the right occipital lobe. After an operation for removal of the hematoma, visual hallucination occurred and persisted for about 6 months. One year and a half later, he had a convulsive seizure and diphenylhydantoin was started. During the two weeks following the convulsion, he several times experienced episodes of visual preservation, visual hallucination and metamorphopsia. MRI revealed an old hemorrhage in the right occipital lobe. 123I-IMP SPECT demonstrated increase of cerebral blood flow of the right medial occipital lobe one day after the episode of visual perseveration and decrease about three weeks after the episode. The mechanism which causes visual perseveration still remains to be clarified. The findings of 123I-IMP SPECT of the present case suggest that visual perseveration may be generated by postictal transient functional excitation of the right occipital lobe.

Aged↗
PubMed1993

Vascular relaxing mechanism of denopamine in isolated canine coronary, femoral, mesenteric, and renal arteries.

We investigated the mechanism of vascular relaxation produced by denopamine (deno), an oral positive inotropic agent that has selective beta 1-adrenergic action. Deno concentration-dependently (0.1 microM-30 microM) relaxed ring segments of canine femoral, mesenteric, and renal arteries which were partially precontracted with 1 micron phenylephrine or norepinephrine, but did not relax those precontracted with 5 microM prostaglandin F2 alpha or 40 mM K+. The relaxation was not significantly inhibited by pretreatment with 10 microM propranolol or metoprolol. Deno produced a parallel rightward shift in concentration-response curves to phenylephrine in femoral and renal arteries. The Schild plot yielded linear regressions of slopes of 1.301 +/- 0.106 and 0.823 +/- 0.122, respectively, which were not significantly different from unity. The pA2 values of Deno against phenylephrine in femoral and renal arteries were 5.41 +/- 0.03 and 5.76 +/- 0.06, respectively. On the other hand, Deno concentration-dependently (10 nM-10 microM) relaxed ring segments of canine coronary arteries which were partially precontracted with 5 microM prostaglandin F2 alpha. The relaxation was significantly inhibited by pretreatment with 10 microM metoprolol. In conclusion, vascular smooth muscle relaxation by Deno was mediated through beta 1-adrenergic action in canine coronary arteries and through the blocking effect of alpha-adrenoceptors in canine femoral, mesenteric, and renal arteries.

Adrenergic beta-Agonists↗
PubMed1993

Effects of rHuEPO therapy on exercise capacity in hemodialysis patients with coronary artery disease.

We investigated the effects of recombinant human erythropoietin (rHuEPO) therapy on exercise capacity by symptom-limited maximal treadmill exercise testing in 9 patients with coronary artery disease who were receiving maintenance hemodialysis. The initial hemoglobin concentration of 7.9 +/- 0.7 g/dl, (mean +/- S.D.) rose to 10.4 +/- 1.1 g/dl, (p < 0.01) after three months of rHuEPO therapy. The partial correction of renal anemia resulted in a significant increase in exercise duration (from 278 +/- 84 sec to 384 +/- 74 sec, p < 0.01) and maximum pressure-rate product (from 228.3 +/- 50.3 mmHg.bpm/10(2) to 262.8 +/- 40.4 mmHg.bpm/10(2), p < 0.01). The maximum exercise-induced ST segment depression significantly decreased after treatment (from 1.3 +/- 0.5 mm to 0.5 +/- 0.5 mm, p < 0.05). These results suggest that the improvement in maximum coronary oxygen supply exceeded the increased maximum myocardial oxygen requirements after the partial correction of renal anemia by rHuEPO therapy in hemodialysis patients with coronary artery disease.

Adult↗
PubMed1993

[Evaluation of left ventricular systolic function by pulsed Doppler echocardiography in patients with acute myocardial infarction].

Left ventricular systolic function in patients with acute myocardial infarction was assessed by Doppler echocardiographic measurement of left ventricular ejection flow velocity and maximum acceleration in 20 patients with initial acute anteroseptal myocardial infarction (group A) and 15 age-matched normal subjects. All patients underwent emergency reperfusion therapy by direct percutaneous transluminal coronary angioplasty (direct PTCA). Pulsed Doppler echocardiograms were obtained from sample volume immediately below the aortic valve in the apical long-axis view. Three parameters, peak velocity, ratio of acceleration time to ejection time (AT/ET) and maximum acceleration, were measured by the Doppler analysis program. Changes in the 3 parameters from the day of admission to the 3rd post-admission day were also observed in 15 patients. Although no significant difference was observed in AT/ET in the 2 groups, peak velocity and maximum acceleration in the patient group were significantly lower than those in the normal group (peak velocity: 90.8 +/- 13.1 vs 99.4 +/- 9.7 cm/sec, p < 0.05, maximum acceleration: 2,692.4 +/- 604.5 vs 3,410.2 +/- 712.5 cm/sec2, p < 0.01, respectively). Between the admission and 3rd day, peak velocity and AT/ET did not change significantly, but maximum acceleration increased significantly (2,720.5 +/- 676.7, 1st day vs 3,313.9 +/- 947.5 cm/sec2, 3rd day, p < 0.05). These results indicate that the maximum acceleration measured by pulsed Doppler echocardiography is useful for assessing global left ventricular systolic function in acute myocardial infarction. Direct PTCA results in improved ventricular systolic function on the 3rd post-operative day.

Adult↗