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Biomedical subjects

M Ichikawa

Publications and source records attributed to M Ichikawa.

At least 37 records · Page 2Linked to original sources
PubMed2001

Plasma thrombin-antithrombin III complex is associated with the severity of experimental autoimmune encephalomyelitis.

Previous studies have shown that activation of blood coagulation and fibrin depositions around CNS vessels are observed in animals with experimental autoimmune encephalomyelitis (EAE), which provides an animal model for human autoimmune demyelinating disorders. We examined the values of peripheral blood fibrinogen, thrombin-antithrombin III complex (TAT), fibrinolytic activity, and fibrin degradation products in Lewis rats with EAE to elucidate the role of the blood coagulation-fibrinolysis system in EAE. Plasma TAT values increased immediately prior to development of symptoms, and decreased according to the improvement of symptoms. There was significant correlation between TAT values and clinical scores of EAE; other markers were not correlated with the symptoms of EAE. These results suggest that plasma TAT levels are sensitive markers of the severity of EAE, and may be useful clinical indicators for the severity of human autoimmune demyelinating disorders.

Animals↗
PubMed2001

Metabolic activation of mitomycin C by NADPH-ferredoxin reductase in vitro.

Mammalian NADPH-ferredoxin reductase (EC 1.18.1.2) functions in the mitochondrial electron transport chain for cytochrome P-450-dependent steroid hydroxylation. Significant homology of three-dimensional structure exists in the surroundings of FAD between NADPH-ferredoxin reductase and NADH-cytochrome b5 reductase. The latter is involved in the bioreduction of mitomycin C (MC), a prototype antitumor agent. In this study, we assessed the capacity of NADPH-ferredoxin reductase to activate MC. Mitomycin C increased the NADPH oxidase activity of NADPH-ferredoxin reductase. In the absence of ferredoxin, the Km value of NADPH-ferredoxin reductase for MC was 73.5 +/- 2.3 microM. While in the presence of 500 nM ferredoxin, a Lineweaver-Burk plot exhibited a biphasic curve. NADPH-ferredoxin reductase-mediated reduction of MC resulted in the formation of an alkylated complex of 4-(p-nitrobenzyl) pyridine and an increase in plasmide DNA single-strand breaks under hypoxic conditions. With the addition of 500 nM ferredoxin, the amount of the alkylated complex of 4-(p-nitrobenzyl) pyridine and the plasmide DNA single-strand breaks increased by 40% and 37%, respectively. However, neither alkylated complex of 4-(p-nitrobenzyl) pyridine nor DNA strand breaks was observed in the presence of SOD and catalase under aerobic conditions. These findings demonstrate that NADPH-ferredoxin reductase is capable of catalyzing the bioactivation of mitomycin C under hypoxic conditions in vitro.

Alkylation↗
PubMed2001

A primary culture system of rat olfactory bulb forming many synapses similar to intact ones and spontaneously generating synchronous intracellular calcium oscillations.

Previously, several studies attempting to analyze olfactory functions using dissociated culture systems of the olfactory bulb (OB) have been reported. Reciprocal dendrodendritic synapses between secondary neurons (mitral/tufted cells) and interneurons (periglomerular/granule cells) are considered to play the most important role in signal processing in the OB. However, it is unclear whether these reciprocal synapses are formed in vitro in the same way as they are in the intact OB. Thus, we synaptologically investigated the nature of cultured OB neurons. These neurons from embryonic rats were classified into four groups based on the size of their somata and their glutamic acid decarboxylase (GAD) immunoreactivity. At 14 days in vitro, most of the neurons synchronously showed spontaneous intracellular Ca2+ oscillations that were reversibly inhibited by application of D-APV and CNQX. Moreover, the frequency of the oscillations decreased and their amplitude became larger following application of bicuculline. These results suggest functional glutamatergic synaptic coupling and inhibitory GABAergic synaptic modulation. Immunocytochemical staining revealed many dot-like products (puncta) that were immunoreactive to GAD as well as to synaptophysin surrounding the cultured neurons. These results strongly indicate the presence of GABAergic synapses. The existence of synaptic contacts in OB neuron cultures was also confirmed by electron microscopy. Two types of synapses, symmetrical and asymmetrical, were morphologically recognizable. Moreover, we could also identify peculiar synapses resembling the in vivo reciprocal dendrodendritic synapses. The use of these primary culture systems will facilitate the elucidation of mechanisms underlying olfactory functions.

Animals↗
PubMed2001

Simultaneous multi-site recordings of neural activity with an inline multi-electrode array and optical measurement in rat hippocampal slices.

Understanding neuronal network function requires multi-site recording. An optical imaging method using voltage-sensitive dyes (VSD) is one such suitable method. It is also important to complement this technique with methods that measure other physiological parameters of neuronal network activity. We aimed to develop a multi-channel electrode method that would easily permit the simultaneous optical imaging of neural activity in vitro. There are several multi-electrode systems; some of these are commercially available, but they are not easy to use and are also expensive. We developed a novel, less expensive, stainless steel inline electrode array that utilizes the standard etching method of circuit board manufacturing. This method, along with widely available computer drawing software, allowed us to produce electrode arrays with uniform quality in electrical characteristics and shapes. The electrode array was designed so that it could easily substitute for single electrode systems without modifying the conventional set-up used for electrophysiological measurements and optical recordings. Simultaneous measurement of evoked neural activities in area CA1 of the rat hippocampal slice with our optical imaging method using the VSD Di-4-ANEPPS is demonstrated in this paper. The electrode array was also used as a stimulating electrode, and the evoked response was measured by the optical recording method. The results demonstrate the advantages of simultaneous recordings obtained by these complementary multi-site recording methods in vitro.

Animals↗
PubMed2001

The optical interconversion of the P-450 and P-420 forms of neuronal nitric oxide synthase: effects of sodium cholate, mercury chloride and urea.

We investigated whether or not neuronal nitric oxide synthase (nNOS) (EC 1.14.13.39) was converted to the P-420 form on exposure to sodium cholate, mercury chloride or urea, and the reconversion of the P-420 to the P-450 form. Sodium cholate and mercury chloride induced the conversion of nNOS from the P-450 to the P-420 form in concentration- and incubation time-dependent manners, and the nNOS activity decreased. In the presence of glycerol, L-arginine and/or tetrahydrobiopterin, the sodium cholate-treated P-420 form could be reconverted to the P-450 form under constant experimental conditions, and the nNOS activity could also be restored. The mercury chloride-treated P-420 form of nNOS could be reconverted to the P-450 form on incubation with reduced glutathione (GSH) or L-cysteine, and the nNOS activity was recovered. However, no reconversion of the mercury chloride-treated P-420 form to the P-450 form was observed in the presence of glycerol, L-arginine, or tetrahydrobiopterin. Urea (4.0 M) dissociated nNOS into its subunits, but nNOS remained in the P-450 form. The nNOS monomer was more susceptible to sodium cholate. After removing the urea by dialysis, and supplementation of the nNOS solution with glycerol, L-arginine or BH(4), the P-420 was reconverted to the P-450 form, and the reassociation of nNOS monomers was also observed. These results suggested that nNOS was more stable as to exposure to sodium cholate, mercury chloride or urea in comparison to microsomal cytochrome P-450, which may be due to the different heme environment and protein structure.

Animals↗
PubMed2001

Low synthesis of retinoic acid due to impaired cytochrome P450 1a1 expression in mouse xeroderma pigmentosum fibroblasts.

New tumor formation was suppressed by retinoic acid (RA) administration in xeroderma pigmentosum (XP) patients who have a defect in nuclear excision repair. However, the inhibition is not due to enhanced removal of UV-damaged DNA. These results prompted us to investigate whether or not RA metabolism is abnormal in XP fibroblasts and what the underlying mechanism is. Compared with wild type fibroblasts, low activities of RA synthesis were determined on HPLC in mouse fibroblasts lacking XP group A (XPA) gene and UV-induced XPA deficient cancer cells. Moreover, we observed an impaired expression of cytochrome P450 1a1 in XPA deficient fibroblasts by RT-PCR and a decreased expression of retinoic acid receptor gamma in XPA deficient cancer cells by Western blotting. Finally, pre-treatment of RA isoforms significantly protected the XPA deficient fibroblasts from UV-induced death. These results suggest that decreased structure activity of RA synthesis, resulting from impaired mRNA expression of cytochrome P450 1a1 may, at least together with UV irradiation, involve in skin carcinogenesis in XP patients.

Alitretinoin↗
PubMed2001

Killer T-cell induction in patients with blastic natural killer cell lymphoma/leukaemia: implications for successful treatment and possible therapeutic strategies.

A rare form of putative natural killer (NK) cell lymphoma called blastic NK cell lymphoma appears to be clinicopathologically distinctive in showing a homogenous lymphoblast, variable expression of CD2, CD4, CD56 and TdT, negative for surface CD3, T-cell receptor antigen, CD16, CD34 and lack of association with Epstein-Barr virus (EBV). We report two patients with blastic NK cell lymphoma and describe the interesting clinical studies. The patients presented with cutaneous plaques. Both patients had adenopathy, and one had marrow involvement at presentation. Unlike in many NK and NK-like T-cell disorders, azurophilic cytoplasmic granules were absent. They expressed intermediate density CD45. In addition, the cells were positive for HLA-DR, CD2, CD4, CD56 and TdT, and negative for EBV transcripts. In spite of the advanced clinical stage, complete remission was achieved by conventional chemotherapy. After interleukin 2 expansion of tumour-infiltrating bone marrow and lymph node cells from the patients, cytotoxic T-cell lines with rearranged T-cell receptor genes were established. They showed specific killing activity against autologous tumour cells in an MHC-restricted fashion, with possible implications for treatment. In addition, upon cessation of maintenance chemotherapy, one patient developed overt leukaemia with blasts expressing CD33 antigens, suggesting a continuous spectrum of blastic NK cell lymphoma to myeloid/NK cell precursor acute leukaemia.

Aged↗
PubMed2001

Free vascularized toe joint transfer to the hand. A technique for simultaneous reconstruction of the soft tissue.

Twelve patients underwent reconstruction of injured finger joints using our technique of a vascularized transfer of the second toe proximal interphalangeal joint. The age of the patients at operation ranged from 7 to 47 years and the postoperative follow-up was 9 to 48 months. All the joint transfers survived and united with resolution of the preoperative joint pain, deformity and instability. The average range of motion of the reconstructed joints was 59 degrees in the proximal interphalangeal and 54 degrees in the metacarpophalangeal joints. No patient complained of pain or functional deficits in the donor foot.

Adolescent↗
PubMed2001

Immunocytochemical study of G(i)2alpha and G(o)alpha on the epithelium surface of the rat vomeronasal organ.

To investigate in detail the distribution of G protein subtypes G(i)2alpha and G(o)alpha along the surface of the vomeronasal epithelium, we used double labeling immunocytochemical methods and electron microscopy. We examined the immunoreactivity of these surface structures with antibodies against G(i)2alpha and G(o)alpha. G(i)2alpha- and G(o)alpha-positive cells were observed at the epithelial surface and were evenly distributed. Electron microscopy revealed that strong immunoreactivities to both antibodies were observed on the microvilli and knob-like surface structures of receptor cells. No immunoreactivity was found on the microvilli or surface membranes of supporting cells. This expression pattern is similar to that reported for putative pheromone receptors. These data confirm that there are two distinct classes of vomeronasal receptor cells expressed at the surface of the epithelium. These two classes of receptors correspond to the same G(i)2alpha- and G(o)alpha-positive cells distributed in cell body layers of the epithelium and in the axon terminals in the accessory olfactory bulb.

Animals↗
PubMed2001

How to distinguish garlic from the other Allium vegetables.

The establishment of international monographs for herbs is in progress. Here, we propose both a marker compound and a method for its analysis for the identification of garlic bulbs and their products. The constituents in 26 kinds of fresh edible parts of Allium vegetables and three types of garlic preparations were analyzed. Sulfur compounds are the most characteristic constituents in garlic, but manufacturing processes of garlic products dramatically affect these constituents. Thus, no sulfur compound could be specified as a universal marker of identification applicable for any type of garlic. On the other hand, garlic contains other characteristic compounds, namely, saponins. After analyzing Allium vegetables and garlic preparations, we concluded that sapogenins, especially beta-chlorogenin, may be a viable candidate for identifying and distinguishing garlic from other Allium vegetables.

Allium↗
PubMed2001

The mouse putative pheromone receptor was specifically activated by stimulation with male mouse urine.

To detect the biological activity of mammalian putative pheromone receptors (V1Rs and V2Rs), the mouse V1R gene was introduced into a primary culture of vomeronasal cells using the adenovirus expression system, and the response of these cells to mouse urine was analyzed by calcium imaging. These cells specifically responded to male but not female mouse urine. This response was attenuated by pertussis toxin, a specific inhibitor of G-protein G(ialpha)/G(oalpha) coupling from receptors. Our findings indicate that a putative pheromone receptor was specifically activated by mouse urine, a major source of mouse pheromones, and suggest that G(i)/G(o) are functionally coupled with the receptor.

Amino Acid Sequence↗
PubMed2001

[Clinical evaluation of an immunochromatography test for rapid diagnosis of influenza].

We evaluated a rapid diagnostic kit that detects influenza type A and B viral antigens by immunochromatography, Quick Vue Influenza Test (Quidel Corp., San Diego, CA, USA), with 425 specimens collected from patients with influenza-like symptoms at three hospitals between January and March 2001. The specimens included 184 nasal aspirates, 140 nasal swabs, and 101 throat swabs. The test correctly identified 179 of the 204 culture positive specimens and 203 of the 221 culture negative specimens; the sensitivity and specificity compared with the culture were 87.7% and 91.9%, respectively. The sensitivity of the test was 92.6% (112/121) for nasal aspirates, 83.7% (41/49) for nasal swabs, and 76.5% (26/34) for throat swabs, which is similar to the results for conventional rapid enzyme immunoassay kits for influenza virus infection. The sensitivity and specificity of the QuickVue Influenza Test were equivalent to those of Flu OIA (BioStar, Inc., Boulder, CO, USA), with the agreement of 84.2%. Although the QuickVue Influenza Test does not differentiate between influenza A and B viruses, the easy-to-use kit detects both types in the physician's office, allowing physicians to make a decision on prescription of neuraminidase inhibitor therapy during the initial visit.

Evaluation Studies as Topic↗
PubMed2001

Prostacyclin inhibits the production of MMP-9 induced by phorbol ester through protein kinase A activation, but does not affect the production of MMP-2 in Human cultured mesangial cells.

BACKGROUND/AIMS: The imbalance between degradation and synthesis of the glomerular extracellular matrix (ECM) causes glomerular sclerosis in various types of glomerulonephritis. We investigated the effect of prostacyclin, which is an inflammatory mediator, on the production of matrix metalloproteinase (MMP)-9 and MMP-2 in human cultured mesangial cells. The synthesis of Jun proteins and Ets-1 proteins, which are related with MMP-9 gene, was also studied. METHODS: The production of MMP-9 and MMP-2 was investigated by gelatin zymography. Western blotting was undertaken to analyze the protein synthesis of Jun and Ets-1. RESULTS: Prostacyclin inhibited the production of MMP-9 induced by phorbol ester. The inhibitory effect by prostacyclin was reversed in part by the pretreatment with an inhibitor of protein kinase A, such as H-89. Forskolin also inhibited the production of MMP-9. The production of MMP-2 was constitutionally seen and was not influenced by prostacyclin and forskolin. The synthesis of Jun protein augmented by phorbol ester was suppressed by prostacyclin. Ets-1 protein was constitutionally synthesized and was not affected by phorbol ester and prostacyclin. CONCLUSION: Prostacyclin plays an important role in inflammatory glomerular disorders by regulating the metabolism of ECM. The production of MMP-9 and MMP-2 may be under the different control pathways.

Carcinogens↗
PubMed2001

Esophageal inflammatory pseudotumor mimicking malignancy.

A 54-year-old man with a complaint of dysphagia was found to have a prominent stricture in the proximal esophagus. A biopsy of the stenotic area indicated sarcoma, leading to subtotal esophagectomy. The surgically removed esophagus demonstrated a well-defined intramural mass, consisting of a mixture of fibroblastic cells with bland cytological appearances and inflammatory cells. Reflux esophagitis which was present distal to the stricture seemed to play a role in the development of this inflammatory pseudotumor.

Adult↗
PubMed2001

[Aortitis syndrome associated with ulcerative colitis, preceded by pulmonary infarction involvement].

A 21-year-old woman with a 6-year history of ulcerative colitis admitted to our hospital with chest pain, cough and fever of unknown origin in August 1998. On admission, laboratory data showed positive inflammatory signs. A chest radiograph and chest computed tomogram (CT) revealed nodular shadows in the right upper lung field. Fifty days after admission, hypertension developed and a bruit was audible in the neck and the upper abdomen. Digital subtraction angiography showed stenosis in carotid, renal and right upper pulmonary arteries. On the basis of these results, a diagnosis of aortitis syndrome was made. Moreover, these findings indicated pulmonary infarction in the right upper lobe due to aortitis syndrome. Aortitis syndrome preceded by pulmonary infarction involvement is very rare. Autoimmune disorders may have been involved in this case because of the association with ulcerative colitis.

Adult↗
PubMed2000

Nonredundant roles of the elongation factor MEN in postimplantation development.

The MEN/ELL gene was cloned as a fusion partner of the MLL gene in the t(11;19)(q23;p13.1) translocation, which is found in adult myeloid leukemia. MEN belongs to a family of RNA polymerase II elongation factors and dysregulated production of MEN through the MLL promoter could cause malignant transformation of myeloid cells. To pursue the physiological role and determine the requirement of the MEN gene product in mouse development, we generated knockout mice (MEN-/-) by gene targeting in embryonic stem cells. After intercrossing heterozygous mice to generate homozygous mutants, we identified no homozygotes (MEN-/-) even at E9.5, as well as after birth, by Southern analysis. Moreover, histological examinations revealed degenerative changes in nearly one-fourth of E6.5 embryos, which were gradually resorbed by E8.5. Our findings demonstrated that MEN-/- mice are embryonic lethal, and die before E6.5 and after implantation. MEN should play a nonredundant role in postimplantation development of mice.

Adult↗