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Biomedical subjects

K Masuda

Publications and source records attributed to K Masuda.

At least 667 records · Page 37Linked to original sources
PubMed1985

Reassembly of a regularly arranged protein in the cell wall of Lactobacillus buchneri and its reattachment to cell walls: chemical modification studies.

Regularly arranged protein (RA protein) isolated from the cell wall of Lactobacillus buchneri was chemically modified by amidination, acetylation, succinylation, and amidation. The modified RA proteins were examined for their ability to reassemble into a regular array and to reattach to the cell walls from which the regular array had been detached. Only amidinated RA protein could be either reassembled into a regular array or reattached to the cell walls; RA proteins modified by the other methods lost the ability for both reassembly and reattachment. The unmodified RA protein could be reattached to periodate-oxidized cell walls, but not to methylated ones. These results suggest that the positive charge of the amino group as well as the negative charge of the carboxyl group of RA protein plays an important role(s) in morphogenesis of the hexagonal array and in its attachment to the underlying cell wall layer. The periodate-insensitive lone hydroxyl groups of the neutral polysaccharide molecule in the cell wall seem to be the receptor sites for RA protein in the attachment to the cell wall.

Bacterial Proteins↗
PubMed1984

Second report of an experimental study of cerebrocardiopulmonary resuscitation (CCPR) in dogs with reference to a new continuous brain cooling method, using a Resusci Pump TM-1.

In our previous report, the effect of CCPR (an intracarotid hypothermic infusion combined with the existing CPR) has been described by the authors on dogs in which cardiac arrest had been induced by the inhalation of nitrous oxide. This report contains a new continuous brain cooling method, using a Resusci Pump TM-1 which has been newly devised by us and which has a carotid-carotid bypass in order to reduce oxygen consumption and cerebral metabolism while maintaining a continuous cerebral blood flow. Cardiac arrest was induced experimentally by electrical stimulation. The duration of cardiac arrest was 5 to 10 min duration. The continuous brain cooling was carried out during the period of 10-30 min. Through the experiment, we have investigated vital signs, acid base balance, cardiac output, carotid arterial blood flow, oxygen availability of the brain tissue, and regional cerebral blood flow in both groups of CPR and CCPR . As for the clinical signs and cardiac output, there were no significant differences between two groups. Oxygen availability of the brain tissue and regional blood flow were much more improved in CCPR group than in CPR group. The brain was selectively cooled by means of the continuous brain cooling. This resulted in the minimum effect on circulatory and respiratory system as compared to the effects caused by general hypothermia. Furthermore, the continuous brain cooling decreased cerebral metabolism and CMRO2, and prevented a progressive development of cerebral hypoxia Cerebral perfusion at a given constant pressure may protect the brain tissue from the disturbance of cerebral microcirculation. Therefore, we might expect the continuous brain cooling to have a beneficial effect on cerebral respiration, circulation and metabolism.

Acid-Base Equilibrium↗
PubMed1984

The effects of acetylcholine, carbamylcholine and gamma-aminobutyric acid on uropod motoneurons in the crayfish Procambarus clarkii and Cambaroides japonicus.

The effects of acetylcholine (ACh), carbamylcholine and gamma-aminobutyric acid (GABA) on the spike activity of uropod motoneurons were investigated electrophysiologically in the crayfish Procambarus clarkii Girard and Cambaroides japonicus de Haan. High concentrations of ACh were required to bring about an increase in the spike discharge of uropod motoneurons while carbamylcholine, which is not destroyed by cholinesterase, caused a marked increase in the motoneuron spike discharge even in low concentrations. Application of GABA in concentrations of 10(-5)-10(-2) M caused the decrease in the spike discharge of uropod motoneurons. Under the condition that the synaptic transmission onto uropod motoneurons was blocked by perfusing EGTA containing Ca2+-free saline with high-Mg2+, ACh increased the spike discharge of uropod motoneurons whereas GABA decreased it. The results suggested that ACh and GABA function as excitatory and inhibitory transmitters, respectively, in the crayfish central nervous system.

Acetylcholine↗
PubMed1984

Types of ocular attacks and lysosomal enzymes in Behçet's disease.

The activities of the lysosomal enzymes of leukocytes were correlated with the types of ocular attacks of Behcet's disease, ie, the anterior or posterior types. No significant correlation was found between the types of attacks and the activities of acid phosphatase and beta-glucuronidase. Myeloperoxidase (MPO) activity in the neutrophils, however, was significantly lower in the posterior type than in the anterior type. In selected cases, the time-course of the MPO activity was studied: the activity decreased at attacks and showed a recovery as the symptoms subsided. The recovery after the attacks was faster in the anterior type than in the posterior type. The difference between the MPO activities in the two types of attacks was thought to be due to the fact that the posterior type attack shows more severe ocular inflammation than the anterior type attack. It is possible that the MPO is released from the neutrophils just before the onset of the ocular attacks.

Acid Phosphatase↗
PubMed1984

[Assessment of the exposure of pest control operators to organophosphorus pesticides. Organophosphorus pesticides in blood and alkyl phosphate metabolites in urine].

Pest control operators usually spray pesticides in small areas such as a kitchen in a restaurant and are exposed to various pesticides, especially those of the organophosphorus (OP) type. In order to evaluate their occupational exposure to OP pesticides during the work, OP pesticides in blood and alkyl phosphate metabolites in urine of these operators were analyzed and the relationship between pesticide exposure and analytical results were studied. OP pesticides in blood were analyzed by gas chromatography with flame photometric detector (FPD-GC) after separation of phospholipid in blood with silicagel column chromatography. OP pesticides were not detected in any blood samples (the limit of detection was 1 ng/ml). Dimethylphosphate (DMP) and dimethylthiophosphate (DMTP), being urinary metabolites of OP pesticides, were analyzed by FPD-GC after benzyl derivatization. This method eliminated interfering peaks in gas chromatograms. The ratio of two isomeric derivatives of DMTP was found to be constant. Both DMP and DMTP of the exposed group were significantly higher than those of the non-exposed group, DMP being higher than DMTP. The ratio of DMP to DMTP in the fenitrothion-dichlorvos-exposed group was significantly higher than that in the fenitrothion-exposed group. It was considered that the ratio might reflect a result of pesticide exposure. The urinary metabolites of OP pesticides tended to become lower with the lapse of time since the last exposure. However, small amounts were detected in a few samples even 5 days after the last exposure.

Adult↗
PubMed1984

Resistance to tolerance induction is not prerequisite to development of murine SLE.

Four different SLE-prone mice, NZB, (NZB x NZW)F1, MRL/MpJ-lpr/lpr, and male BXSB/MpJ, resisted the induction of tolerance to human IgG (HGG) at 5 wk, but not before 3 wk of age. However, female F1 hybrids between NZW and BXSB mice were easily made tolerant to HGG, although they develop an acute form of typical SLE similar to that seen in (NZB x NZW)F1 hybrid females. In addition, C57BL/6 mice bearing a mutant gene, lpr (lymphoproliferation), which produced significant amounts of various autoantibodies characteristic of murine SLE, were still as susceptible to tolerance induction as control C57BL/6 mice. In contrast, both (NZW x BXSB)F1 and (C3H x BXSB)F1 hybrid males carrying the abnormal Y chromosome of BXSB mice failed to become tolerant to HGG, although the extent of resistance to tolerance induction was less significant in (C3H x BXSB)F1 males than in (NZW x BXSB)F1 males. Our results suggest that 1) the defect in tolerance induction to heterologous IgG such as HGG is not necessarily required for the development of an SLE-like syndrome in mice; 2) the induction or enhanced production of autoantibodies by the lpr gene is not related to this cellular abnormality; but 3) a Y chromosome-associated factor from BXSB mice plays a significant role in the abnormality to resist tolerance induction as well as the acceleration of SLE. Our observations are consistent with the hypothesis that SLE may be based on highly specific abnormalities of immune responses to particular autoantigens, but not on a generalized breakdown of a tolerance mechanism.

Animals↗
PubMed1984

Water flow in Tenon's capsule and subconjunctival tissue of rabbit.

The mode of water flow in the Tenon's capsule and the subconjunctival tissue was studied in the rabbit. Carbon-black ink injected under the Tenon's capsule was found to move along the plane of the capsule posteriorly toward the optic nerve sheath and also along the direction of the corneal limbus, but a very little amount moved through the layers of the capsule. The flow rates of physiological saline through the capsule were determined under various hydrostatic pressures, and the water flow conductivity through the capsule averaged 8.8 +/- 5.5 X 10(-12) cm4 dyne-1 sec-1 in 7 eyes. The Tenon's capsule offered a considerable resistance to water flow through its layers. The upper conjunctiva was dissected to the limbus and the wound was closed 1) after subconjunctival injection of saline and 2) after injection of concentrated sodium hyaluronate. One month later, a needle connected to a saline reservoir was inserted into the subconjunctival tissue of the treated area and the rate of water flow into the tissue was determined under various hydrostatic pressures. The results were compared with those in the normal eye. The water flow rate was significantly less in the treated eye than in the normal eye. The eyes treated with sodium hyaluronate tended to show a higher flow rate than those treated with saline. Histological examinations revealed that an intensive scar formation took place in the dissected area, indicating that scar formation greatly reduces water flow in the Tenon's capsule and subconjunctival tissue.

Animals↗
PubMed1984

Induction of various autoantibodies by mutant gene lpr in several strains of mice.

The effect of the autosomal mutant gene lpr (lymphoproliferation) on the development of various autoantibodies and immune complex (IC) glomerulonephritis was investigated in four genetically distinct strains of mice: MRL/ MpJ , C3H/HeJ, C57BL/6J, and AKR/J. The presence of the lpr gene not only enhanced the production of autoantibodies in the autoimmune MRL/ MpJ strain, but also induced the formation of various kinds of autoantibodies in the three other strains of mice without any apparent predisposition to autoimmune disease. Autoantibodies induced by the lpr gene included anti-double-stranded DNA, anti-single-stranded DNA, anti-IgG, anti-thymocyte, and anti-serum glycoprotein gp70. This indicates that the action of the lpr gene on the development of autoantibody response does not require the particular abnormalities of the MRL genome. The differences in amounts and types of autoantibodies among the lpr strains reflect the difference in the background genome of each strain, suggesting the participation of other genes or factors determining the quantity and/or specificity of autoantibodies. In addition to the development of autoantibodies, the three nonautoimmune strains of mice produced high levels of unidentified IC in the presence of the lpr gene, detectable by the C1q and the conglutinin binding tests. Their glomerular lesions, however, were relatively limited when compared with MRL/ MpJ -lpr/lpr mice, which developed severe glomerulonephritis early in their life. These results suggest that the lpr gene is able to induce the formation of various autoantibodies and IC at significant concentrations in nonautoimmune mice, but for the full manifestation of systemic lupus erythematosus there may be a requirement for supplemental genetic abnormalities or factors.

Animals↗
PubMed1984

Acute SLE in F1 hybrids between SB/Le and NZW mice; prominently enhanced formation of gp70 immune complexes by a Y chromosome-associated factor from SB/Le mice.

Both sexes of the F1 hybrids between SB/Le and NZW mice developed a spontaneous lupus-like disease. Their disease is essentially identical in time course and nature with autoimmune responses that are seen in the F1 hybrids between BXSB and NZW mice. The presence of abnormal Y chromosomes in the SB/Le strain was proved by the finding that the accelerated disease occurred in the F1 hybrid males only when the male parent was SB/Le but not NZW. The acceleration of disease in male F1 hybrids with abnormal Y chromosome was significantly associated with the enhanced formation of gp70 IC but not anti-DNA antibodies. These results indicate that all or almost all of the genetic abnormalities expressed in the BXSB strain are contributed by the SB/Le strain, and the Y chromosome-associated factor enhances the autoimmune response to serum gp70 antigen more markedly than to DNA antigens.

Acute Disease↗