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Biomedical subjects

Osamu Igarashi

Publications and source records attributed to Osamu Igarashi.

At least 19 recordsLinked to original sources
PubMed2006

Reduction in the motor unit number estimate (MUNE) after cerebral infarction.

BACKGROUND: The mechanism of the decrease in motor unit number estimates (MUNEs) after cerebral infarction has not been studied systematically. We examined the relationship between the degree to which MUNEs decreased and the other clinical features of patients with the infarction. METHODS: Using a multiple point stimulation technique, we obtained the MUNE of the hypothenar muscle group in 13 age-matched control subjects and 30 patients with cerebral infarction. In all patients, we obtained the Japan Stroke Scale (JSS) and head MR images. In eight patients with acute cerebral infarction, admitted within 24 h after onset, we also obtained head MR angiograms and single-photon emission CT. FINDINGS: There was a decrease in the MUNE of the hypothenar muscle group on the affected side of 24 patients with cerebral infarction and hand weakness. The decrease in the MUNE started from 4 to 30 h after the infarction, when T1-weighted MR images of the brain involved were normal. The degree to which the MUNE decreased correlated with the part of the JSS showing the upper extremity weakness. INTERPRETATIONS: A decrease in the MUNE of the hypothenar muscle group within 30 h after cerebral infarction may be due to trans-synaptic inhibition of the spinal alpha motor neurons innervating this muscle.

Action Potentials↗
PubMed2005

Cheiro-oral-pedal syndrome due to brainstem hemorrhage.

Cheiro-oral-pedal syndrome is characterized by specific sensory disturbance around the corner of the mouth, in the hand and in the foot on the same side. Lesions responsible for causing this syndrome vary. We report two cases of cheiro-oral-pedal syndrome due to midbrain and pontine hemorrhage, respectively. Pontine hemorrhage producing cheiro-oral-pedal syndrome has been reported in three cases, but this is the first case that midbrain hematoma exhibits this syndrome. Damage in the sensory pathway can cause cheiro-oral-pedal syndrome. Difference in the threshold may explain the specific sensory pattern in this syndrome. Cheiro-oral-pedal syndrome is caused by lacunar infarction in majority of the cases. However, it should be kept in mind that hematomas can cause cheiro-oral-pedal syndrome.

Cerebral Hemorrhage↗
PubMed2005

Cheiro-pedal syndrome following pontine infarction.

We report the case of a 64-year-old man with sudden onset of numbness in the right hand and foot. Neurological examinations were normal except for hypersthesia, and hyperalgesia of the right hand and foot. Brain MRI demonstrated a high signal intensity on T2-weighted image and a low signal intensity on T1-weighted image in the left tegmetum of the pons. He was diagnosed with pontine infarction presenting with cheiro-pedal syndrome (CPS). Damage in the sensory pathways can cause CPS. Difference in the threshold may explain the specific sensory pattern in this syndrome. Further examination of the relationship between sensory symptoms and localization on MRI is needed to clarify this syndrome.

Brain Stem Infarctions↗
PubMed2004

Intracellularly expressed TLR2s and TLR4s contribution to an immunosilent environment at the ocular mucosal epithelium.

Epithelial cells are key players in the first line of defense offered by the mucosal immune system against invading pathogens. In the present study we sought to determine whether human corneal epithelial cells expressing Toll-like receptors (TLRs) function as pattern-recognition receptors in the innate immune system and, if so, whether these TLRs act as a first line of defense in ocular mucosal immunity. Incubation of human primary corneal epithelial cells and the human corneal epithelial cell line (HCE-T) with peptidoglycan or LPS did not lead to activation, at the level of DNA transcription, of NF-kappaB or the secretion of inflammation-associated molecules such as IL-6, IL-8, and human beta-defensin-2. However, when incubated with IL-1alpha to activate NF-kappaB, the production by these cells of such inflammatory mediators was enhanced. Human corneal epithelial cells were observed to express both TLR2- and TLR4-specific mRNA as well as their corresponding proteins intracellularly, but not at the cell surface. However, even when LPS was artificially introduced into the cytoplasm, it did not lead to the activation of epithelial cells. Taken together, our results demonstrate that the intracellular expression of TLR2 and TLR4 in human corneal epithelial cells fails to elicit innate immune responses and therefore, perhaps purposely, contributes to an immunosilent environment at the ocular mucosal epithelium.

Cornea↗
PubMed2004

T-588 protects motor neuron death following axotomy.

R(-)-1-(benzo [b] thiophen-5-yl)-2-[2-(N,N-diethylamino)ethoxy] ethanol hydrochloride) (T-588) enhances acetylcholine release. This compound slows the motor deterioration of wobbler mouse motor neuron disease and enhances neurite outgrowth and choline acetyltransferase activity in cultured rat spinal motor neurons. We examined the ability of T-588 on axotomized spinal motor neuron death in the rat spinal cord. After the postnatal unilateral section of sciatic nerve, there was approximately a 50% survival of motor neurons in the fourth lumbar segment. In comparison with vehicle, intraperitoneal injection of T-588 for 14 consecutive days rescued spinal motor neuron death. Our results showing in vivo neurotrophic activity of T-588 for motor neurons support the applicability of T-588 for the treatment of motor neuron diseases, such as amyotrophic lateral sclerosis and motor neuropathies.

Animals↗
PubMed2004

Gamma-tocopherol enhances sodium excretion as a natriuretic hormone precursor.

Endogenous natriuretic factors are believed to be responsible for extracellular fluid homeostasis in mammals. A new endogenous natriuretic factor, Loma Linda University-alpha (LLU-alpha) has recently been proven to be a 2,7,8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman (gamma-CEHC), which is a metabolite of gamma-tocopherol (gamma-Toc). The purpose of this study was to investigate whether gamma-Toc could accelerate sodium excretion into rat urine as a natriuretic hormone precursor. Male SD strain rats were divided into two groups; one was a control diet group, while the other was a high NaCl group (50 g/kg diet). Next, the two groups were each subdivided into two groups consisting of a placebo group and a gamma-Toc group. After the oral administration of one experimental dose of 20 mg gamma-Toc or placebo, rat urine was collected at 6 h intervals for 24 h, and then the urine volume, sodium and potassium and gamma-CEHC content were determined. gamma-Toc increased in the urine volume of the high-NaCl intake group. The sodium excretion in the high-NaCl group given gamma-Toc was 8.29+/-2.20 g, while in the control group given gamma-Toc it was 6.24+/-1.49 g from 12-18 h. In contrast, the potassium excretion in the rat urine did not change in any of the groups. Our findings suggested that gamma-Toc accelerates the degree of sodium excretion in rats with a high sodium intake.

Administration, Oral↗
PubMed2004

Lymphatic absorption of structured triacylglycerols, 1(3)-stearoyl-2,3 (1)-dilinoleoylglycerol and 2-linoleoyl-1,3-distearoylglycerol in rats.

Lymphatic recovery of 1(3)-stearoyl-2,3(1)-dilinoleoylglycerol (SLL) and 2-linoleoyl-1,3-distearoylglycerol (SLS) which had been enzymatically synthesized were compared with those of trilinoleoylglycerol (LLL) and the randomly esterified triacylglycerol which contained stearic acid and linoleic acid at 1:2. Recoveries of linoleic acid in all of the triacylglycerols were more than 94.0%. Lymphatic 24 h-recoveries of stearic acid given as SLL and SLS were significantly lower than that of stearic acid given as the randomly esterified triacylglycerol. Recoveries of stearic acid from SLL, SLS and the randomly esterified triacylglycerol were 88.49%, 68.3% and 101%. respectively.

Absorption↗
PubMed2003

Gamma-tocotrienol, a vitamin E homolog, is a natriuretic hormone precursor.

2,7,8-Trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman (gamma-CEHC), a metabolite of gamma-tocopherol and gamma-tocotrienol, was identified as a new endogenous natriuretic factor. However, gamma-tocopherol and gamma-tocotrienol, both precursors of gamma-CEHC, have never directly been observed to have natriuretic potency. Thus, we investigated whether gamma-tocotrienol could cause natriuresis and diuresis in rats. The rats were divided into two groups that were given a control or a high-sodium diet for 4 weeks, and then subdivided into placebo and gamma-tocotrienol subgroups given only corn oil-removed vitamin E and oil supplemented with gamma-tocotrienol, respectively. After oral administration of three experimental doses, rat urine was collected and gamma-CEHC, urine volume, sodium, and potassium content were determined. Only in rats given a high-NaCl diet did gamma-tocotrienol accelerate and increase sodium excretion, showing no effect on potassium excretion. Sodium excretion in the high-NaCl group given gamma-tocotrienol was 5.06 +/- 2.70 g/day, and in the control group given gamma-tocotrienol, 0.11 +/- 0.06 g/day. Furthermore, gamma-tocotrienol affected urine volume in the specific condition of high-NaCl body stores and gamma-tocotrienol supplementation. In this study, we found that gamma-tocotrienol, one of the natural vitamin E homologs, stimulates sodium excretion in vivo, suggesting that gamma-tocotrienol possesses a hormone-like natriuretic function.

Animals↗
PubMed2003

The relation of clinical symptoms and anti-ganglioside antibodies to MEPPs frequency increase in 8 cases of variant type Guillain-Barré syndrome.

Many patients with variant forms of Guillain-Barré syndrome (vGBS) associated with anti-ganglioside antibodies, including Miller Fisher syndrome (MFS), sometimes exhibit miniature endplate potential (MEPP) frequency increases (MFI, described as alpha-latrotoxin-like effects in a previous report) and the factor to produce this effect is present in their sera. MFI-positive sera increase the frequency of MEPPs, then block neuromuscular transmission at the mouse neuromuscular junction. A connection between this effect at the neuromuscular junction and some vGBS symptoms is suspected. We measured MFI directly at several points during the clinical course of 8 vGBS patients who had various symptoms and courses. Six patients had confirmed MFI and this activity decreased with convalescence. In 3 clinically mild cases, we were able to elicit MFI using normal serum to supply complement after exposure to the patient's serum. The anti-GQ1b/GT1a IgG titer, the extent of ophthalmoplegia and the extent of MFI were significantly correlated. They did not correlate with the severity of limb weakness or the occurrence of respiratory failure. These results support the hypothesis that MFI caused by anti-ganglioside antibodies is the pathogenic mechanism responsible for ophthalmoplegia in vGBS; different mechanisms or antibodies may explain limb weakness and respiratory failure. Furthermore, MFI may be an important indicator of how serum injures the nerve terminals. The symptoms of vGBS may result from multiple pathogenic factors.

Adult↗
PubMed2003

Temocapril prevents motor neuron damage and upregulation of cyclooxygenase-II in glutamate-induced neurotoxicity.

To examine the possible neuroprotective effect of temocapril, one kind of angiotensin-converting enzyme inhibitor, against glutamate-induced neurotoxicity, we analyzed the pharmacologic utility of temocapril in a post-natal organotypic culture model of motor neuron degeneration. Treatment with 10(-5) M of glutamate resulted in a motor neuron loss and decreased activity of choline acetyltransferase (ChAT). Cotreatment of 10(-5) M of glutamate and temocapril revealed protective effect on motor neuron death and decreased activity of ChAT. Next we performed reverse transcription-PCR analysis for cyclooxygenase-II (COX-II). COD-II mRNA was upregulated in glutamate-treated culture. Cotreatment with temocapril and glutamate inhibited upregulation of COX-II. Taken together, temocapril may have therapeutic potential for diseases which associate with upregulation of COX-II, in addition to its role in glutamate excitotoxicity.

Angiotensin-Converting Enzyme Inhibitors↗