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Biomedical subjects

M Mogi

Publications and source records attributed to M Mogi.

At least 91 records · Page 5Linked to original sources
PubMed1991

Okadaic acid stimulates the activity of the nerve growth factor-sensitive S6 kinase of PC12 cells.

PC12 pheochromocytoma cells contain at least two different and separable kinases that phosphorylate the S6 protein of the ribosomes. The activity of one of these S6 kinases is increased by treatment of the cells with nerve growth factor and of the other by treatment with epidermal growth factor. Okadaic acid increases the activity of the nerve growth factor-sensitive S6 kinase. The data suggest that the nerve growth factor-sensitive S6 kinase is activated by phosphorylation on serine or threonine residues and is inactivated by either phosphatase 1 or phosphatase 2A, probably the latter.

Animals↗
PubMed1991

Effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration in prenatal stage on the dopamine system in the postnatal mouse brain.

A dopaminergic neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine (MPTP), administered to a pregnant female was found to affect postnatally the catecholamine metabolism of the pups. MPTP (5 mg/kg body weight/day) was administered to pregnant C57 Black BYA mice daily for 7 days between the 12th and 18th day of gestation. Dopamine levels and tyrosine hydroxylase (TH) activity were measured in the whole brain from the pups sacrificed after birth. In MPTP-treated pups at 7 days of age, TH total activity (TH activity/brain) did not change (92% of the control value), while TH specific activity (TH activity/mg protein) was increased to 163% of that in control mice. Thus, TH homospecific activity (TH activity/mg TH protein) doubled compared to the control mice. At 28 days of age, both the total activity and the specific activity of TH in the brains of postnatal mice were reduced to 50% and 78% of the control, respectively. Dopamine concentration in the striatum was also reduced significantly. Reduction in the TH activity and dopamine concentration were also observed at the age of 12 weeks. These data suggest that the prenatal exposure to MPTP induced a prolonged reduction of TH activity in the brains of mice with a transient increase of TH homospecific activity during the postnatal period.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1991

Distribution of biting Culex tritaeniorhynchus (Diptera: Culicidae) among pigs: effects of host size and behavior.

The distribution of biting Culex tritaeniorhynchus Giles females among pigs was analyzed to determine the effect of host size and behavior on host selection by the mosquitoes. The number of Cx. tritaeniorhynchus collected per sow was significantly greater than that on her piglets. Sleeping piglets were attacked more frequently by mosquitoes than wakeful ones. The distribution of biting mosquitoes among different-sized piglets was aggregated compared with expected random distribution, and one of four data sets showed significant host size-dependence. Pig activity (including mosquito defensive behavior) significantly reduced the number of attacking mosquitoes, but total pig activity score was not related significantly to total mosquito counts during the early half of the night or the entire night. Data on the residence times of mosquitoes on pigs indicated that interrupted (and consequently multiple feedings) were frequent. The effects of size-dependent (age-dependent) host selection by Cx. tritaeniorhynchus on the amplification of Japanese encephalitis virus were discussed in relation to control programs.

Analysis of Variance↗
PubMed1991

Gastric microcirculation and its regulating factors in stress.

Gastric mucosal blood flow and its regulating factors were studied in normal and stressed rats. In addition, vascular regulating factors and the role of CoQ10 anion radical and SOD (superoxide dismutase) level in gastric mucosa were also investigated as well as the influence of 5-HT (5-hydroxytryptamine) on gastric mucosal blood flow. Gastric mucosal blood flow was measured by the hydrogen gas clearance method. The vascular pattern of the stomach was investigated by the infusion method with two-colored silicon rubber. CoQ10 anion radical and SOD levels in gastric tissue were assayed by electron spin resonance (ESR) and radioimmunoassay. The gastric mucosal blood flow decreased significantly early after the induction of stress. Impairment of gastric mucosal blood flow was highly correlated with 5-HT and CoQ10 anion radical and SOD levels. Reduction in gastric mucosal blood flow was consequently due to opening of arteriovenular shunt and hyperpermeability of true capillaries influenced by 5-HT. These results demonstrate that ischemia and reperfusion after reduction of the gastric mucosal blood flow resulted in the sequence of events that led to formation of acute gastric mucosal lesions.

Animals↗
PubMed1991

Pharmacokinetics of nizatidine in dogs and rats.

1. Plasma levels of nizatidine and two metabolites (N-desmethyl nizatidine and nizatidine S-oxide) were studied in dogs and rats. 2. The time-courses of plasma concentration of nizatidine after i.v. and oral administration to dogs well fitted a two-compartment model. Absorption after oral administration was rapid, and the peak plasma level (Cmax) and area under the plasma concentration-time curve (AUC) were proportional to doses. Absolute bioavailability was close to 100%, indicating that nizatidine has a negligible first-pass effect. 3. Nizatidine was eliminated by apparent first-order kinetics after i.v. administration to rats, and the elimination in rats was faster than in dogs. Bioavailability in rats was 72.4%, indicating a slight first-pass effect in rats. 4. When plasma clearance (Clp), or volume of distribution (Vd.beta), of nizatidine were plotted against animal body weight on a log-log scale, good correlations were obtained for rats, dogs and humans. 5. Peak levels (Cmax) of two metabolites were reached at 0.5-1.0 h after oral and i.v. administration of nizatidine to dogs. The elimination curves of the two metabolites were similar to that of nizatidine. Significant relationships were found between doses of nizatidine and Cmax or AUC of both metabolites.

Administration, Oral↗
PubMed1990

Right-left asymmetry of tyrosine hydroxylase in rat median eminence: influence of arterial baroreflex nerves.

Arterial baroreceptor nerves consist of 2 pairs of nerves, carotid sinus and aortic. The latter nerves differ bilaterally as to size and origin suggesting that central baroreceptor activity could be asymmetrical. This was tested by studying activity of tyrosine hydroxylase (TH), the rate limiting enzyme for catecholamine synthesis, on right and left sides of the brain in median eminence (ME), arcuate nucleus (ARCN), paraventricular nucleus (PVN) and supraoptic nucleus (SON). Seven days after right or left sinoaortic denervation (SAD), bilateral SAD or sham-operation (SO), in situ TH activity was determined by the rate of dihydroxyphenylalanine (DOPA) accumulation following administration of a dopa decarboxylase inhibitor. Unexpectedly, the intact, SO rats had significantly lower DOPA concentrations on the left than right sides of ME in two separate studies; right-left differences averaged 24% and 38%. Evidence supporting asymmetry of TH activity was the lower concentrations of catecholamines on left than right sides of the brain in intact SO rats, namely, dopamine in ME and ARCN and norepinephrine and epinephrine in ARCN. Unilateral and bilateral SAD further suppressed TH activity on the left side of the ME; the maximum right-left difference was 58% in rats with right SAD. Their ARCN also showed asymmetry of TH activity. Asymmetry of TH activity was attributable to asymmetry of TH protein which was significantly lower on the left sides of ME and ARCN. This is the first demonstration of bilateral asymmetry of TH in mediobasal hypothalamus and its enhancement by interruption of left or right afferents from the arterial vascular system.

Animals↗
PubMed1990

Applicability of presence-absence and sequential sampling for ovitrap surveillance of Aedes (Diptera: Culicidae) in Chiang Mai, northern Thailand.

Applicability of presence or absence sampling for ovitrap surveillance of Aedes aegypti (L.) and Aedes albopictus (Skuse) was examined for data collected in Chiang Mai, northern Thailand. Distribution of eggs per trap was contagious but did not fit the negative binomial distribution with a common k. The relationship between the mean number of eggs per trap and the proportion of positive traps was described using Gerrard & Chiang's model, which does not assume particular distribution patterns. Using this relation, the mean number of eggs per trap with confidence limits can be estimated without egg counts. Potential usefulness of presence or absence sequential sampling for decision making (when to initiate vector control for prevention of dengue hemorrhagic fever) was shown.

Aedes↗
PubMed1990

Colonization of rice fields by mosquitoes (Diptera: Culicidae) and larvivorous predators in asynchronous rice cultivation areas in the Philippines.

Colonization of rice fields by mosquitoes and larvivorous predators was studied in asynchronous rice cultivation areas in the Philippines. Dipper samples were taken from rice fields at six phases of maturity (fallow, ploughed, nursery, newly transplanted, after tillering, mature). All phases were present concurrently at each of two study sites. Abundance levels of the vishnui subgroup of Culex and of the genus Anopheles were high in ploughed fields, nurseries, and newly transplanted fields; this was primarily because of the concentration of Culex vishnui. Theobald and Anopheles vagus Doenitz in those fields with short, sparse vegetation. Dytiscidae, Anisoptera, and Zygoptera were more abundant in fallow or mature fields. The abundance of aquatic predators decreased at the onset of ploughing and then recovered slowly as rice plants grew. The abundance of surface predators showed a similar pattern, but less conspicuously. The abundance of nonpredators (other than mosquitoes) was relatively stable with regard to rice field phases. Alleviation of mortality by predation was considered to be a secondary cause of increased mosquito abundance in the fields under early phases of rice cultivation.

Animals↗
PubMed1990

Alternation of gastric mucosal glycoprotein (lectin-binding pattern) in gastric mucosa in stress. A light and electron microscopic study.

Gastric mucosal cells of the rat glandular stomach were studied by light and electron microscopic procedures by use of lectins in the development of acute gastric mucosal lesions. Effects of the H2-receptor antagonist sofalcone (2'carboxymethoxy-4,4'-bis 3-methyl-2) and truncal vagotomy with pyloroplasty on lectin binding sites and distribution were also investigated. Biotinylated lectins in combination with ABC (avidin-biotinyl peroxidase complex) method were used for light and horseradish peroxidase (HRP)-labeled lectins for electron microscopic studies. Gastric mucosal cells showed the specific binding pattern for each lectin by light microscopy. Especially, binding sites and distribution of peanut agglutinin (PNA) were characteristic after induction of stress, truncal vagotomy, and administration of each drug. Staining and distribution increased in the gastric mucosa upward and downward after that. In electron microscopic studies, PNA strongly stained the membranes of the intracellular secretory canaliculi of a parietal cell. These results suggested that alternation of binding sites and distribution was regulated by change of gastric mucosal blood flow and of acidity in the parietal cells. Therefore, increase of glycoconjugate distribution is supposed to be a possibility of cytoprotective effect for a change of environment in the parietal cells.

Animals↗
PubMed1990

[Basic study on the chemosensitivity test by miniaturized improved nucleic acid precursor incorporation assay (MINI assay)].

UNLABELLED: Miniaturized improved nucleic acid precursor incorporation assay (MINI assay) has been developed by Kern D. H. and Tanigawa N. et al since 1985. We investigated in vitro effects of mitomycin C (MMC), cisplatin (CDDP) and bleomycin (BLM) against A 549 lung cancer cells and HeLa cells by MINI assay. RESULTS: 3H-thymidine (3H-TdR) uptake in the positive control was 734.2 cpm +/- 10 cpm. The cut-off level for in vitro sensitivity was defined as more than 80% inhibition of 3H-TdR uptake in the drug treated cells compared to the positive controls. A 549 cells were sensitive to MMC (81.6%), CDDP (78.6%), but not to BLM (-57%). HeLa cells were sensitive to MMC (91%), CDDP (79.4%), but not to BLM (43%). MINI assay could be done with fewer cells than other methods and the results were obtained within 5 days. This method was considered to be useful for the chemosensitivity test with human tumors.

Antineoplastic Agents↗
PubMed1990

[Alteration of the gastric mucosal glycoprotein in stress].

Many studies have postulated the role of gastric acid and mucosal microcirculation in the development of gastric ulcer. We considered that gastric mucosal glycoprotein played one of the most important roles as the defensive factors of te gastric mucosa. The purpose of this study is to investigate te location and distribution of glycoprotein in the gastric mucosa in normal and stressful condition. Male Wistar rats, weighing 250 g were used as the experimental animals. Alternation and distribution of glycoprotein in the gastric mucosa were studied by light and electron microscopic examination employing HRP-labeled lectin such as PNA, DBA, ConA, RCA, SBA, WGA and UEA-1 as a parameter before and after the development of stress ulcer. Around Thirty percent scalding burn of the rat body surface area was created. At 2, 5 and 24 hours after burn induction, the gastric mucosa was examined. PNA-binding sites which were primarily localized to the generative cell zone in the control rat appeared to extend from the upper layer to the intermediate or the basal layer of the gastric mucosa in accordance with the development of stress ulcer after burn. Most of the binding sites was detected in the parietal cells particularly along microvilli in the intracellular secretory canaliculi. The tubulovesicular system in the parietal cells became stainable with PNA in the stress-loaded rats. Alternation and binding pattern of lectin, especially of PNA may indicate the local response of the parietal cells of the gastric mucosa against the stress.

Animals↗
PubMed1989

Beta 2-microglobulin decrease in cerebrospinal fluid from parkinsonian patients.

A sandwich enzyme immunoassay (EIA) was established by using purified beta 2-microglobulin (beta 2-MG) as a standard protein and a polyclonal antibody raised against human beta 2-MG. The EIA was applied for the measurement of beta 2-MG levels in human cerebrospinal fluid (CSF) from parkinsonian patients and control patients devoid of neurological diseases. beta 2-MG contents in CSF of the control group and the parkinsonian group were 1.81 +/- 0.11 micrograms/ml CSF and 0.63 +/- 0.09 microgram/ml CSF, respectively. Thus, beta 2-MG content in CSF was reduced in parkinsonian patients to less than 35% of the control value (P less than 0.005). We had previously reported that the activity and content of dopamine beta-hydroxylase (DBH) were decreased in CSF from parkinsonian patients. A significant positive correlation (r = 0.87) was observed between the beta 2-MG content and DBH activity for CSF from 45 patients. These results suggest a probable link between an immunological change and the changes in catecholaminergic neurons in Parkinson's disease.

Adult↗
PubMed1989

Effectiveness of zooprophylaxis in malaria control: a theoretical inquiry, with a model for mosquito populations with two bloodmeal hosts.

A model for a vector mosquito population with two bloodmeal hosts (man and a domestic animal) was developed to study the influences of domestic animals on the frequency of mosquito bites on man and the endemicity of human malaria. The vector population model, including blood-feeding success in the adult stage (depending on host density and biting efficiency) and density-dependent regulation in the larval stage, was combined with the Ross-Macdonald malaria transmission model. Model analyses suggested that introduction of domestic animals easily fed upon by mosquitoes increases mosquito density and, in some situations, frequency of mosquito bites on man and the infection rate of malaria through increased success of blood-feeding. Extinction of malaria was predicted only when an extremely large number of easily accessible (as compared to man) domestic animals are introduced. Limitations in the concept of zooprophylaxis and problems of livestock management in malaria control are discussed.

Animals↗