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Biomedical subjects

M Ohashi

Publications and source records attributed to M Ohashi.

At least 469 records · Page 26Linked to original sources
PubMed1982

Ganglioside patterns of frog nervous tissues.

Frog gangliosides were prepared from the brain and the peripheral nerves and investigated by neuraminidase treatment. The precise distribution patterns of the total gangliosides and their hydrolysis products were analyzed by multiple two-dimensional thin-layer chromatography. It was found that frog nervous tissues contained unique gangliosides which were easily hydrolyzed by neuraminidase and converted into asialo-GM1, suggesting the presence of new linkages of the sialic acids.

Animals↗
PubMed1982

Studies on the neutralizing antibody to herpes simplex virus. III. Detection of type-specific antibody by slow-reacting complement-requiring neutralizing antibody assay.

The type-specific antibody responses in rabbits immunized with both types of herpes simplex virus (HSV), measured by complement-requiring neutralizing (CRN) and slow-reacting CRN (s-CRN) antibody assays were compared. Titers of type-specific antibody measured by s-CRN antibody assay were always markedly higher than those measured by CRN antibody assay. The s-CRN antibody assay was so sensitive that even an undetectable level of CRN antibody could be readily detected by this method. The detection of type-specific antibody by s-CRN antibody assay may be useful when attempting to analyze human HSV infection.

Animals↗
PubMed1981

Low-density lipoprotein as a potential vehicle for chemotherapeutic agents and radionucleotides in the management of gynecologic neoplasms.

Cholesterol metabolism was studied in cells from two established gynecologic cancer cell lines which were maintained in monolayer cultures. The cell lines were derived and established from poorly differentiated epidermoid cervical carcinoma (EC-50) and endometrial adenocarcinoma (AC-258). The specific activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, the rate-limiting enzyme of cholesterol de novo synthesis, in AC-258 cells (1,700 pmoles x mg-1 microsomal protein x min-1) was three times higher than that found in EC-50 cells (550 pmoles x mg-1 microsomal protein x min-1). However, epidermoid cervical cancer cells (EC-50) metabolized low-density lipoprotein (LDL), the major transport vehicle for cholesterol in plasma, at a very high rate (14,000 ng x mg-1 cell protein x 6 hours). This rate is fifteen times greater than the rate observed in fetal adrenal tissue and fifty times greater than the rate observed in nonneoplastic gynecologic tissue, each in organ culture. Both cancer cells (EC-50 and AC-258) in monolayer culture were shown to have specific receptors for LDL. These cancer cells demonstrate no defect in LDL metabolism, and lysosomal degradation of LDL was blocked by chloroquine. From the results of studies of specific binding of LDL in tissues obtained from nude mice it was demonstrated that membrane fractions prepared from EC-50 cells, after propagation in the mice, contained fifteen to thirty times more specific binding capacity for [125I]iodo-LDL than vital organs of the mouse, such as the liver, heart, lung, kidney, or brain. The results of these studies are suggestive that certain tumor cells might have a higher affinity for LDL than normal tissues and cytotoxic drugs or radionucleotides ligated to the LDL macromolecule may be utilized for the specific delivery of these agents.

Adenocarcinoma↗
PubMed1981

Studies on the neutralizing antibody to herpes simplex virus. I. Effect of heterotypic antigenic stimulus on the type specificity of neutralizing antibody in rabbits.

Effect of heterotypic antigenic stimulus on the antibody response in rabbits previously exposed to only one type of virus was investigated. The complement requiring neutralizing antibody (CRN) was found in the IgM fraction as well as the IgG, but the conventional neutralizing antibody (N) was detected only in the fraction containing IgG. The CRN antibody found in the IgM fraction was most predominantly modified by the inoculation of heterotypic virus, and resulted in a relative increase of CRN antibody titres against the heterotypic virus, whereas antibodies in the IgG fraction, either CRN or N, were slightly affected by the heterotypic stimulus. When the heterotypic virus was given 9 months after the initial inoculation of homotypic virus, the antibody response in teh IgM fraction formed the same pattern as seen in the primary response against the type of virus inoculated as the booster. These findings should pave the way for making accurate serological assessments, including the type of virus in present infections, irrespective of involvement of a superinfection with the heterotypic virus.

Animals↗
PubMed1981

Studies on the neutralizing antibody to herpes simplex virus. II. Quantitative analysis of type specific antibodies in rabbits immunized with both types of virus.

A quantitative analysis was carried out on type specific antibody developed in rabbits primed with three doses of one type of herpes simplex virus at two week intervals, followed by administration of another type of virus. Complement-requiring neutralizing antibody assay and mutual absorbing methods were used. The homotype specific antibody produced against the type of virus used for priming persisted at a constant level for a long period, despite the lack of antigenic stimuli by the same type after priming. The homotype specific antibody was not affected by the heterotypic antigenic stimuli. On the other hand, the heterotype specific antibody developed after the first or second injection of heterotypic virus, and the titer tended to decline, reaching undetectable levels at 9 months. However, the heterotype specific antibody was produced rapidly after the third injection of virus at 9 months and the titers exceeded or closed to those of the homotype specific antibody. The homotype specific antibodies were mainly distributed in the IgG fraction, while the IgM fraction contained mainly the heterotype specific antibodies. In relationship between type specific antibody response and the values of II/I index, the coexistence of both type specific antibodies was apparent in sera with the values of 91 to 117 of II/I index and in the IgG fraction with the values of 90 to 115, respectively.

Animals↗
PubMed1981

Experimental studies on the effect of artificial respiration after lightning accidents.

Many suggestions have been made regarding protective methods against lightning, without any quantitative tests of safety. As a fundamental study on lightning protection, the lethal threshold energy for the artificial lightning impulse was investigated, using 14 rabbits. The voltage and current impulse had a 1 microsecond wave front and 40 microsecond wave tail. The imposed energy was measured by simultaneous photographic recording of both voltage and current waves on separate oscilloscopes. The impulse voltage was applied to head, neck, upper chest, and lower chest while the right hind limb was grounded. Artificial lightning current impulses were fed through the skin of the animals by making the surface flash over so that the surface flash was monitored carefully to delete the data of this case which gives an erroneous energy value from the statistical analysis. The lethal threshold energy was found to be 157.6 +/- 54.1 Joule (J), and the percentage of survival was 25% when 160 J impulse energy was given. Impulses of 160 J were then applied to the heads of 21 other rabbits maintained on an artificial respirator. Under these conditions the percentage of survival increased significantly to 47.6%.

Animals↗
PubMed1981

Effect of chest wall vibration on ventilation in patients with spinal cord lesion.

Changes of respiration caused by chest wall vibration were studied in 13 patients with cervical cord lesions. Vibrators applied on the chest wall were intermittently triggered by the patient's respiratory movements. The vibrators were triggered to be applied in three ways. 1) Upper vibrations were bilaterally applied during inspiration on the 2nd or 3rd parasternal intercostal spaces (insp "in-phase" vibration). 2) Lower vibrations were bilaterally applied during expiration on the 7th-to 10th intercostal spaces anterior to midaxillary lines (exp "in-phase" vibration). 3) Inspiratory and expiratory vibrations were combined to produce alternating in phase vibration. Both inspiratory and expiratory vibrations increased tidal volume (VT), but the alternating in-phase vibration increased it to significantly higher values (P less than 0.05). Minute volume of ventilation (VE l/min) also increased with insp or exp in-phase vibration. The alternating in-phase vibration increased VE l/min to even higher values (P less than 0.05). The responses described probably depend on segmental vibration reflexes arising in the inspiratory and expiratory intercostal muscles underlying the vibrators. The alternating in-phase vibration may well be useful to improve the breathing in patients with respiratory insufficiency.

Adolescent↗
PubMed1981

Effects of adrenocorticotropic hormone on low density lipoprotein receptors of human fetal adrenal tissue.

In the present investigation, the mechanism(s) whereby ACTH stimulates low density lipoprotein (LDL) metabolism in human fetal adrenal was evaluated. Plasma membrane fractions were prepared from fetal adrenal tissue fragments incubated in lipoprotein-poor serum with or without ACTH, and the binding of [125I]iodo-LDL to such membrane fractions was examined. The mean specific binding capacity for [125I]iodo-LDL by membrane fractions prepared from four separate fresh human fetal adrenal glands was 1370 +/- 168 ng mg-1 protein (mean +/- SE), and the concentration of [125I]iodo-LDL producing half-maximal binding was 20.8 +/- 1.2 ng ml-1. Thus, the presence of high affinity, low capacity binding sites for LDL in human fetal adrenal tissue was confirmed. When human fetal adrenal tissue was maintained in organ culture for 2 days in medium containing lipoprotein-poor serum in the absence of ACTH, and plasma membrane fractions were subsequently prepared, the binding capacity for LDL in such membrane fractions was the same as or slightly greater than that in membrane fractions prepared from fresh tissue. When ACTH was present in the culture medium, the binding capacity for LDL was doubled compared to that in membrane fractions prepared from tissues incubated in the absence of ACTH. The rate of [125I]iodo-LDL degradation by human fetal adrenal tissue maintained in medium containing ACTH was also twice that of tissue maintained in the absence of ACTH. These results demonstrate that ACTH causes an increase in the number of LDL-binding sites in human fetal adrenal tissue in vitro. This is one mechanism whereby ACTH stimulates LDL metabolism in this tissue.

Adrenal Glands↗
PubMed1981

The role of cyclic adenosine 3',5'-monophosphate in cholesterol metabolism and steroidogenesis by the human fetal adrenal gland.

In the present investigation we studied the role of cAMP as a mediator of ACTH action in human fetal adrenal (HFA) tissue. We have characterized the response to ACTH, dibutyryl adenosine 3',5'-cyclic monophosphoric acid (dbcAMP), and cholera toxin (CT) with respect to steroidogenesis, low density lipoprotein (LDL) binding, degradation of LDL, and the rate of de novo synthesis of cholesterol. The rate of dehydroisoandrosterone sulfate secretion was similar in HFA tissue maintained in the presence of ACTH, dbcAMP, or CT. In contrast, cortisol secretion by HFA tissue was more sensitive to dbcAMP and CT than to ACTH. In membrane preparations obtained from HFA tissue maintained in the presence of ACTH, dbcAMP, or CT, there was a 2 to 3-fold increase of specific binding of [125I]iodo-LDL. In HFA tissue maintained in the presence of ACTH or CT, the rate of degradation of LDL was significantly increased compared to tissue maintained in the lipoprotein-poor serum alone. Finally, in HFA tissue maintained in the presence of ACTH, dbcAMP, or CT there was a 6- to 10-fold stimulation of the rate of incorporation of [14C]acetate into cholesterol. We conclude that steroidogenesis, LDL binding, and degradation, as well as de novo synthesis of cholesterol, are probably stimulated in HFA tissue via a cAMP-mediated pathway.

Adrenal Glands↗