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Biomedical subjects

K Inoue

Publications and source records attributed to K Inoue.

At least 955 records · Page 53Linked to original sources
PubMed1997

Epitope regions in the heavy chain of Clostridium botulinum type E neurotoxin recognized by monoclonal antibodies.

Seventeen monoclonal antibodies (MAbs) were previously established against the heavy chain (Hc) of botulinum type E neurotoxin in BALB/c mice immunized with the type E toxoid. Five MAbs (LE15-5, LE34-6, EK19-7, EK21-4, and AE27-9) showed toxin-neutralizing activity in mice. Two of the five MAbs, EK19-7 and EK21-4, recognized the regions located at amino acid positions 731 to 787 and 811 to 897, respectively. One of the remaining three antibodies (LE34-6) reacted with the amino acid sequence VIKAIN, at amino acid positions 663 to 668, closed by the ion channel-forming domain. It is suggested that the ion channel-forming domain may also be associated with the blocking of acetylcholine release. Furthermore, the amino acid sequence YLTHMRD within 30 residues of the C-terminal region of the Hc component seemed to be recognized by LE15-5. It has been reported that the binding domain of the type E toxin is located on the C-terminal half of the Hc component. Therefore, the neutralizing activity of LE15-5 antibody may be attributed to its ability to block the binding of neurotoxin to the receptor of target cells.

Amino Acid Sequence↗
PubMed1997

Unbalanced membrane phospholipid compositions affect transcriptional expression of certain regulatory genes in Escherichia coli.

The amount of porin protein OmpF in the outer membrane of Escherichia coli was reduced to one-third by the pgsA3 mutation that diminishes the amount of phosphatidylglycerol and cardiolipin in the membrane, whereas a cls (cardiolipin synthase) null mutation had no effect. Osmoregulation of OmpF was functional in the pgsA3 mutant. As assessed by the beta-galactosidase activities of lacZ fusions, the ompF expression was not reduced at the transcriptional level but was reduced about threefold at the posttranscriptional level by pgsA3. This reduction was mostly restored by a micF null mutation, and the micF RNA that inhibits the ompF mRNA translation was present 1.3 to 1.4 times more in the pgsA3 mutant, as assayed by RNase protection and Northern blot analyses. Elevation of the level of micF RNA was not restricted to acidic-phospholipid deficiency: OmpF was hardly detected and micF RNA was present 2.7 to 2.8 times more in a pssA null mutant that lacked phosphatidylethanolamine. Other common phenotypes of pgsA3 and pssA null mutants, reduced rates of cell growth and phospholipid synthesis, were not the cause of micF activation. Salicylate, which activates micF expression and inhibits cell motility, did not repress the flagellar master operon. These results imply that an unbalanced phospholipid composition, rather than a decrease or increase in the amount of specific phospholipid species, induces a phospholipid-specific stress signal to which certain regulatory genes respond positively or negatively according to their intrinsic mechanisms.

Bacterial Outer Membrane Proteins↗
PubMed1997

Increase in age at onset of rheumatoid arthritis in Japan over a 30 year period.

OBJECTIVES: To determine changes in demographic variables and severity of rheumatoid arthritis (RA) that may have occurred during the 30 year period from 1960 to 1990 in Japan. METHODS: Using records of patients diagnosed with RA from two hospitals, demographic and clinical features at initial visit were compared between two groups, one from 1960 to 1965 (group I) and the other from 1985 to 1990 (group II). RESULTS: Mean age at the time of onset of the disease increased significantly from 37.5 years in group I to 46.9 in group II. The peak age at onset of RA shifted from the third to the fifth decade between group I and group II. There was no obvious change in morbidity as determined by seropositivity, rheumatoid nodules, and assessments of hip involvement. CONCLUSION: The age at onset of RA was delayed during a recent 30 year period in Japan. This increase in age at onset might result from environmental changes that occurred in Japan or may reflect a birth cohort phenomenon. Improvement of severity of disease was not found in this study.

Adolescent↗
PubMed1997

Voltage-dependent gating of ATP-activated channels in PC12 cells.

The possibility that P2X receptors exhibit voltage-dependent gating in a similar manner to nicotinic receptors was investigated in rat pheochromocytoma cells with the use of whole cell voltage-clamp techniques. In the presence of extracellular ATP, slowly activating inward currents were elicited by stepping from -50 mV to potentials more negative than -80 mV; these currents had a time constant of approximately 60 ms at -120 mV. This slowly activating component (as a fraction of the total ATP-induced current) increased with membrane hyperpolarization from -80 to -100 mV and was much increased when depolarizing prepulses were applied, although the time constant of activation was not altered by depolarizations. The fraction of the slowly activating current and its time constant were decreased as the ATP concentration was increased from 10 to 300 microM. Thus it has been demonstrated that voltage-dependent gating of ATP-activated channels does occur in PC12 cells, and that this gating is modified by agonist concentration. It is possible that such gating may serve as a postsynaptic mechanism to facilitate excitatory neurotransmission by contributing to the inward rectification of the ATP-activated currents.

Adenosine Triphosphate↗
PubMed1997

Proteolytic processing of pro-opiomelanocortin occurs in acidifying secretory granules of AtT-20 cells.

Using antibodies specific for pro-opiomelanocortin (POMC), amidated joining peptide (JP), and the prohormone convertase PC1, we showed immunocytochemically that PC1 in a corticotrophic tumor cell line, AtT-20, was co-localized either with POMC or with amidated JP in secretory granules, and also confirmed that POMC was cleaved mainly in secretory granules. Analysis using DAMP (3- [2,4-dinitroanilino]-3'-amino-N-methyldipropylamine) as the pH probe suggested a correlation between POMC processing and acidic pH in the secretory granules. Bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPase, completely inhibited POMC processing and caused constitutive secretion of the unprocessed precursor. By contrast, chloroquine, a weak base that is known to neutralize acidic organelles, was unable to inhibit POMC processing. Electron microscopic analysis revealed that, in AtT-20 cells treated with bafilomycin A1, the trans-Golgi cisternae were dilated and few secretory granules were present in the cytoplasm. These observations suggest that acidic pH provides a favorable environment for proteolytic processing of POMC by PC1 but is not required, and that integrity of the trans-Golgi network and sorting of POMC into secretory granules are important for POMC processing.

Animals↗
PubMed1997

Regulation of K+ channels by cell contact in a cloned folliculo-stellate cell (TtT/GF).

Membrane currents in a folliculo-stellate cell line (TtT/GF) were examined using the whole-cell clamp technique. The cultured cells were morphologically categorized as isolated spread cells, isolated round cells, contact spread cells, and contact round cells. A distinct outward current was observed in isolated spread cells, contact round cells, and contact spread cells, whereas the outward current detected in isolated round cells was barely perceivable. The reversal potentials of the outward tail current obeyed the Nernst equation, indicating that the outward current was carried by K+ ions. The activation and deactivation processes of the K+ current could be fitted by single exponential curves. 4-aminopyridine, tetraethylammonium, and Ba2+ inhibited the K+ current. The concentrations for half-maximal inhibition of these agents to block the K+ current were 0.2 mM, 0.8 mM, and 8 mM, respectively. The biophysical and pharmacological characteristics of the K+ current in TtT/GF cells were similar to those of the K+ current in glial and Schwann cells. According to the results of the present study, it was concluded that TtT/GF cells possessed outward K+ channels, characteristics of which were similar to those of the K+ channels in glial and Schwann cells, and that the amplitude of the K+ current in TtT/GF cells seemed to be regulated by the condition of the cell contact.

4-Aminopyridine↗
PubMed1997

Involvement of glucocorticoid-induced factor(s) in the stimulation of growth hormone expression in the fetal rat pituitary gland in vitro.

The mechanism by which glucocorticoids induce GH expression between embryonic days 18 and 19 (E18-19) in the fetal rat pituitary gland was examined with an in vitro organ culture system. Twenty-four hour incubation of E18 pituitary glands in serum-free medium containing either dexamethasone (DEX, 5-50 nM) or corticosterone (0.55 microM) resulted in a conspicuous accumulation of GH messenger RNA (mRNA), whereas no spontaneous expression of GH mRNA was noted without glucocorticoid. Triiodothyronine (1 nM) alone weakly induced GH mRNA but increased the effect of DEX 2-fold. The GH mRNA accumulation was not observed after 5 or 10 h incubation with DEX. However, a 10-h incubation with DEX followed by 14 h chase incubation without DEX resulted in apparent induction of GH mRNA. The induction of GH mRNA by DEX was completely inhibited by puromycin. These data, taken as a whole, suggest that the induction of GH mRNA by DEX in the fetal pituitary gland is not a direct effect of DEX on the GH gene but is mediated by a factor that is synthesized in the pituitary gland in response to DEX. Both immunoblot and RNase protection assays suggested that this factor is not pit-1, which is known to be required for GH mRNA expression.

Animals↗
PubMed1997

Mutations in the proteolipid protein gene in Japanese families with Pelizaeus-Merzbacher disease.

Pelizaeus-Merzbacher disease (PMD) is a rare X-linked dysmyelinating disorder of the CNS resulting from abnormalities in the proteolipid protein (PLP) gene. Exonic mutations in the PLP gene are present in 10 to 25% of all cases. In investigating genotype-phenotype correlations, we screened five Japanese families with PMD for PLP gene mutations and compared their clinical manifestations. We identified two novel nucleotide substitutions in exon 5, at V208N and at P210L, in two families. In the remaining three families, there were no mutations detected. Although all patients satisfied the criteria for the classical form of PMD, two families not carrying the mutations showed milder clinical manifestations than those with the mutations. Since linkage analysis has shown homogeneity at the PLP locus in patients with PMD, our findings suggest that there may be genetic abnormalities other than exonic mutations that cause milder forms of PMD.

Apoproteins↗
PubMed1997

Influence of diet on the single-dose pharmacokinetics of isosorbide 5-mononitrate and sustained-release isosorbide dinitrate.

The influence of diet on the single-dose pharmacokinetics of isosorbide 5-mononitrate (IS-5-MN) and sustained-release isosorbide dinitrate (ISDN) was studied in 8 healthy male volunteers. The subjects received either a low-calorie/low-fat diet (LCFD) or a high-calorie/high-fat diet (HCFD) according to a cross-over schedule and were administered the drug in tablet form after breakfast. The study was conducted first in 8 subjects who received a 20 mg IS-5-MN tablet and then in 6 of these individuals who received a 20 mg sustained-release ISDN tablet. After oral doses of IS-5-MN, the plasma drug levels declined monoexponentially and could be described by a one-compartment open model. There were no significant differences in the pharmacokinetic parameters for IS-5-MN between the LCFD and the HCFD. After administration of sustained-release ISDN, the plasma ISDN levels showed marked variations both between and within individuals. The increase in the mean AUC0-12 values for ISDN with the HCFD was found to exceed 60%, although there was no significant difference between the two diets.

Administration, Oral↗
PubMed1997

[ATP receptors in the central nervous system].

ATP receptors in the central nervous system (CNS) are divided into 2 major classes, ionotropic (P2Xn) and G protein-coupled (P2Yn) ATP receptors. P2Xn receptors, a member of the 2-transmembrane family, contain non-selective cation channels that may play a role in rapid synaptic transmission. Seven subtypes of P2Xn were reported so far. Although all of these subtypes are distributed in the CNS, P2X4 and P2X6 are most abundantly and widely distributed. P2X3 is distributed only in trigeminal ganglia neurons as well as in small-diameter DRG neurons, suggesting their relation to pain. P2Yn receptors, a member of the 7-transmembrane superfamily, are coupled with Gq/11 to activate PLC beta. These receptors are thought to play an important role in the modulation of synaptic efficacy. Seven subtypes of P2Yn were reported so far. P2Y1, P2Y2, P2Y3 and P2Y4 are distributed in the CNS. Neither selective agonists nor antagonists to P2Xn and P2Yn are known.

Animals↗
PubMed1997

Chronotoxicity of methotrexate in mice and its relation to circadian rhythm of DNA synthesis and pharmacokinetics.

The mechanisms underlying the circadian rhythm of methotrexate (MTX)-induced toxicity (body weight loss and leukopenia) were investigated from the viewpoints of the sensitivity of living organisms to the drug and the pharmacokinetics of the drug. ICR male mice were housed in a standardized light-dark cycle (lights on at 0700, off at 1900) with food and water ad libitum. The body weight loss after an intraperitoneal injection of MTX (400 mg/kg) was more serious in the late dark period and the early light period and milder in the late light period and the early dark period. The MTX-induced leukopenia was more serious in the late dark period and the light period and milder in the early dark period. Lower toxicity was observed when DNA synthesis, dihydrofolate reductase (DHFR) activity in bone marrow cells and folate level in plasma decreased, and higher toxicity was observed when they increased. There was a significant circadian rhythm in plasma MTX concentration, with a higher level in the light period and a lower level in the dark period. The circadian rhythm of plasma MTX concentration was associated with that of MTX-induced toxicity. The present study suggests that the circadian rhythm of MTX-induced toxicity is caused by that of the sensitivity of living organisms to the drug and the pharmacokinetics of the drug.

Animals↗
PubMed1997

Increase in swimming endurance capacity of mice by capsaicin-induced adrenal catecholamine secretion.

Increase in endurance swimming capacity caused by capsaicin (CAP), a pungent component of red pepper, -induced increase of fat metabolism in mice was investigated using an adjustable-current water pool. The mice administered CAP via a stomach tube, showed longer swimming time until exhaustion than the control group of mice, in a dose-dependent manner. The maximal effect was observed at a dose of 10 mg/kg while more than 15 mg/kg had no effect. The increase of endurance was observed only when CAP was administered two hours before swimming. After the administration of CAP, the serum glucose concentration rapidly increased and then decreased within 60 min, while the concentration of serum-free fatty acids gradually increased through 3 hours. The residual glycogen concentration of the gastrocnemius muscle after 30 min of swimming was significantly higher in the CAP-administered mice than in control mice, suggesting that use of the serum free fatty acids spared muscle glycogen consumption. The serum adrenaline concentration significantly increased with twin peaks at 30 min and two hours after administration of CAP. An experiment using adrenalectomized mice was done to confirm that the effect of CAP is due to increased energy metabolism through the secretion of adrenaline from the adrenal gland. The swimming endurance capacity of the adrenalectomized mice was not increased by CAP administration, although adrenaline injection induced a 58% increase in the endurance time. These results suggest that the increase of swimming endurance induced by CAP in mice is caused by an increase in fatty acid utilization due to CAP-induced adrenal catecholamine secretion.

Animals↗
PubMed1997

Secretory production of erythropoietin and the extracellular domain of the erythropoietin receptor by Bacillus brevis: affinity purification and characterization.

Bacillus brevis secretes a large amount of cell wall proteins into the culture medium. For construction of Bacillus brevis expression-secretion vectors of human erythropoietin (EPO) and the extracellular domain of mouse erythropoietin receptor (sEPOR), cDNA for each mature form was inserted into a plasmid containing the promoter region and the signal-peptide encoding region of a cell wall protein. Culture supernatants of transformants were affinity purified using a monoclonal antibody-fixed gel for EPO and and EPO-fixed gel for sEPOR. The affinity purification efficiently removed unwanted proteins, giving samples with sufficiently high purity to analyze amino acid sequences of N-terminal regions and biological activities. Combination of this secretory production and affinity purification may facilitate isolation of a large amount of pure EPO and sEPOR, and is useful for further understanding the molecular mechanism of interaction between EPO and EPOR.

Amino Acid Sequence↗
PubMed1997

The effect of aging on bone formation in porous hydroxyapatite: biochemical and histological analysis.

The effect of aging on osteoblastic differentiation of marrow stromal stem cells was examined. Porous hydroxyapatite (HA) disks were soaked in cells suspensions of bone marrow cells from young (8 weeks) and old rats (60 weeks) and then implanted subcutaneously in syngeneic young and old rats. The bone marrow/HA composites were harvested 8 weeks later, and the contents of bone Gla protein (BGP) and alkaline phosphatase (ALP) activity in them were determined. Histologically, bone formation could be detected in all the composites in young recipient rats; however, some old bone marrow/HA composites in old recipients did not show bone formation and the bone volume in the young bone marrow/HA composites was greater than in the old bone marrow/HA composites. The ratios of ALP activities of young bone marrow/HA composites to old bone marrow/HA composites in young and old recipients were about five times and four times, respectively. The ratios of BGP contents of young bone marrow/HA to old bone marrow/HA composite in young and old recipients were about nine and eight times, respectively. The results suggest that the decreased bone formation observed in old bone marrow cells was due to a smaller population of stromal cells and/or decreased capacity of differentiation of stromal stem cells into osteogenic cells.

Aging↗
PubMed1997

Histopathological improvement of acromegalic cardiomyopathy by intermittent subcutaneous infusion of octreotide.

We studied functional and histopathological changes in acromegalic cardiomyopathy following intermittent subcutaneous infusion of octreotide. A 68-year-old female patient with acromegaly associated with congestive heart failure due to dilated cardiomyopathy was initially treated with cardioactive medication for three months, but it was not effective in correcting echocardiographic abnormalities. Further treatment with intermittent subcutaneous infusion of octreotide (20 microg/2 h) for 12 months not only reduced circulating GH and insulin-like growth factor-I (IGF-I) levels but also considerably improved histopathological changes in the myocardial specimen biopsied. These findings provide the first evidence of the favorable effect of octreotide on histopathological changes in acromegalic cardiomyopathy.

Acromegaly↗
PubMed1997

Sarcoid reaction in thyroid diseases: report of a case of thyroid carcinoma demonstrating sarcoid reaction in regional lymph nodes.

We describe an extremely rare case of thyroid carcinoma accompanied by sarcoid reaction in regional lymph nodes. The patient, a 40-year-old woman, was found to have anterior neck swelling during a routine medical examination. Physical examination revealed a bad movable and firm nodule measuring 3.5 x 2.5 cm in the right thyroid lobe. Examination of a fine-needle aspiration cytology of the nodule suggested papillary carcinoma of class V. Right lobectomy and isthmectomy with neck dissection were performed. Histopathological examination of the resected specimens revealed papillary carcinoma accompanied by metastatic foci in right perithyroidal lymph nodes and non-caseous sarcoid-like granulomas in pretracheal, right upper internal deep cervical and submandibular lymph nodes. We concluded that these granulomas were due to a sarcoid reaction associated with thyroid carcinoma, after performing examinations to rule out the possibility of systemic sarcoidosis.

Adult↗
PubMed1997

Regulatory functions of phospholipase A2.

Phospholipase A2 (PLA2) plays crucial roles in diverse cellular responses, including phospholipid digestion and metabolism, host defense and signal transduction. PLA2 provides precursors for generation of eicosanoids, such as prostaglandins (PGa) and leukotrienes (LTs), when the cleaved fatty acid is arachidonic acid, platelet-activating factor (PAF) when the sn-1 position of the phosphatidylcholine contains an alkyl ether linkage and some bioactive lysophospholipids, such as lysophosphatidic acid (lysoPA). As overproduction of these lipid mediators causes inflammation and tissue disorders, it is extremely important to understand the mechanisms regulating the expression and functions of PLA2. Recent advances in molecular and cellular biology have enabled us to understand the molecular nature, possible function, and regulation of a variety of PLA2 isozymes. Mammalian tissues and cells generally contain more than one enzyme, each of which is regulated independently and exerts distinct functions. Here we classify mammalian PLA2s into there large groups, namely, secretory (sPLA2), cytosolic (cPLA2), and Ca(2+)-independent PLA2s, on the basis of their enzymatic properties and structures and focus on the general understanding of the possible regulatory functions of each PLA2 isozyme. In particular, the roles of type II sPLA2 and cPLA2 in lipid mediator generation are discussed.

Amino Acid Sequence↗