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Biomedical subjects

T Koga

Publications and source records attributed to T Koga.

At least 757 records · Page 42Linked to original sources
PubMed1977

Some physical properties of free and esterified cholesterol mixtures: studies on relative stability of cholesterol ester ratio in blood plasma.

Some physical properties of the mixtures composed of esterified and free cholesterol at various ratios were measured. Addition of a small proportion of free cholesterol, lowered slightly the melting point of the esterified cholesterol fraction from human plasma and it was kept nearly constant at this level by the addition of 30-40% of free cholesterol. Further addition of free cholesterol resulted in an abrupt rise in the melting point. The ranges of the stable plateau were clearly wider in esterified cholesterol with more polyunsaturated acids. The extent of inhibition of monolayer formation of free cholesterol with cholesterol palmitate was found to be greatest at a mixture ratio of 60-70%. In the case where cholesterol palmitate was added to an equimolar mixture of dipalmitoyl glycerophosphocholine and free cholesterol, a trimolecular mixed monolayer was formed above the mixing ratio, 7.5:2.5, of esterified and free cholesterol. The present studies clearly showed that there were distinct changes in some physical properties examined at the molar ratio of esterified cholesterol:free cholesterol of about 7:3.

Cholesterol↗
PubMed1977

Arthritogenicity of wax D from various mycobacteria related to oil vehicle composition and to the combination with poly I:C, cord factor and acetylated wax D.

Most of wax D (peptidoglycolipid) used here appeared to be ineffective for production of arthritis when given in a water-in-oil emulsion, while the same wax D in squalane was very effective for production of arthritis. Arlacel A as an emulsifier appeared to suppress the arthritogenicity of wax D in squalane, probably through some interaction with the arthritogenic portion of wax D. Poly 1:C seemed to remarkedly enhance the arthritogenicity of wax D, even in water-in-oil emulsion. Acetylated wax D and cord factor (trehalsoe-dimycolate) were much less effective than poly 1:C. Delayed skin hypersensitivity to PPD, peptidoglycan and poly 1:C was also remarkedly affected by oil composition. However, there was no correlation between these delayed hypersensitivities and development of arthritis.

Adjuvants, Immunologic↗
PubMed1976

Induction of adjuvant arthritis in the rat by various bacterial cell walls and their water-soluble components.

A number of purified cell walls of various gram-positive bacteria had arthritogenic activity in the rat. The water-soluble adjuvant-active component(s), which were isolated from some of these cell walls by utilizing a peptidoglycan-degrading enzyme, did produce severe adjuvant arthritis. However, the components obtained by digestion with glycan-degrading enzymes failed to produce arthritis. Thus, the present finding indicates the importance of a peptidoglycan portion, especially its intact glycan chain, for induction of adjuvant arthritis.

Animals↗
PubMed1976

Reevaluation of inguinal lymph node injection for production of adjuvant arthritis in the rat.

An experiment was designed to compare the efficiency of lymph node injection for the induction of adjuvant arthritis (AA) with that of conventional footpad injection in the rat. Quantitative studies revealed that the minimal dose required for induction of AA by the lymph node route is one fifth of that by the footpad route. Thus, the lymph node route was found to be more efficient than the footpad method in terms of higher incidence and earlier onset of AA. PPD in Freund's incomplete adjuvant was able to produce tuberculin sensitization in the rat. The lymph node route again proved to be superior in terms of consistent appearance of the 24-hour reaction on days 8 and 14 and prolongation of the skin reaction over 48 h. These findings show that the lymph node method is so efficient in the rat that it will be especially useful for the trial induction of AA with various materials of unknown potency as well as for production of delayed hypersensitivity. In addition, this injection method appears to be a simple and efficient technique for assay of other immunological reactions.

Animals↗
PubMed1976

Effect of degradation of the arabinogalactan portionof a water-soluble component from M. tuberculosis wax D on polyarthritis induction in the rat.

In order to explore a possible role of the arabinogalactin (AG) portion of the water-soluble arthritogenic component (WAC) from M. tuberculosis wax D for induction of adjuvant arthritis (AA) in the rat, this component was digested with an AG-degrading enzyme. The enzyme-digested WAC was able to produce AA. The severity of AA was almost comparable to that of the nondigested WAC. This finding suggests that the AG portion of the WAC does not seem to be essential for AA induction and indirectly points the importance of the peptidoglycan portion.

Animals↗
PubMed1976

Synergism of immunogenic and adjuvant-active components of mycobacterial wax D in the induction of adjuvant arthritis.

Two derivatives of wax D, one possessing immunogenicity and the other adjuvant activity, were tested for the possible role in the induction of adjuvant arthritis (AA) in rats. The former, a water-soluble arthritogenic and immunogenic component (WAC), in incomplete Freund's adjuvant, was able to induce delayed hypersensitivity (DH) and mild AA, but failed to function as an adjuvant in rats. The latter, an acetylated wax D (AD) and its subfraction, AD6, did exert adjuvant activity, but were free from immunogenicity and arthritogenicity. The addition of AD or AD6 to the WAC in incomplete Freund's adjuvant, when injected into inguinal lymph nodes, resulted in the production of severe AA with high incidence. Other adjuvants such as pertussis vaccine and lipopolysaccharide could not replace AD6; they failed to enhance AA when combined with the WAC. Also, other mycobacterial antigen, PPD, could not replace wax D-derived WAC; it did not induce AA when coupled with AD6, although it did induce DH to PPD.

Adjuvants, Immunologic↗
PubMed1976

Structural requirements for arthritogenicity of peptidoglycans from Staphylococcus aureus and Lactobacillus plant arum and analogous synthetic compounds.

The comparative studies on the arthritogenicity of chemically well defined peptidoglycans (PG)2 from the cell walls of Staphylococcus aureus (FDA 209P) and Lactobacillus plantarum (ATCC 8014) showed that 1) a polymer of disaccharide-peptide with or without the presence of N-acetylglucosaminyl-ribitol-teichoic acid produced severe arthritis; 2) oligosaccharide-peptides with or without the special structure (N-acetylglucosaminyl-ribitol-teichoic acid in S. aureus, a polymer of rhamnose and glucose in L. plantarum) produced severe disease; 3) disaccharide-heptapeptide-disaccharide with or without the presence of either glucose-ribitol-teichoic acid or a polymer of rhamnose and glucose appeared to be arthritogenic but much less effective for disease production; 4) N-acetylmuramyl-heptapeptide-N-acetylmuramic acid and disaccharide-hexapeptide were non-arthritogenic; 5) none of the synthetic N-acetylmuramyl-peptides, including tetrapeptide, produced the disease. Thus it is concluded that arthritis-inducing activity is related to the peptidoglycan moiety but not to the special structure, and the most important moiety responsible for disease production may be located in a chain length of two or more disaccharide units on PG subunits. However, it is discussed that non-arthritogenicity of peptidoglycans, including synthetic compounds, may be due to a lack of adjuvanticity in rats rather than a lack of antigenic determinant(s) responsible for production of arthritis.

Animals↗
PubMed1976

Role of T lymphocytes in adjuvant arthritis. I. Evidence for the regulatory function of thymus-derived cells in the induction of the disease.

Rats of Wistar King Aptekman (WKA) were thymectomized at 4 weeks of age and injected with Mycobacterium tuberculosis wax D 6 weeks after the operation to induce adjuvant arthritis. The development of this disease was strikingly enhanced by this treatment. Further experiments showed that a 4- to 6-week interval between thymectomy and wax D injection was necessary to show the enhancing effect. Such enhancement by thymectomy was also shown in rats of another strain, Sprague-Dawley (SD). The enhancing effect of thymectomy was abolished when thymocytes of normal syngeneic rats were transferred to thymectomized rats 7 days before the wax D inoculation. Furthermore, severe arthritis was also produced in WKA rats that were pretreated with low dose (200 R) whole body irradiation, but not in those treated with higher doses (400 to 700 R). These results seem to indicate that the enhancing effect is brought about by selective depletion of a certain population of T lymphocytes. The population depleted may be thymus dependent, short-lived and radiosensitive, the properties of which agree whith those known for suppressor T lymphocytes. Thus, it appears that thymus-derived cells could normally exert a regulatory effect on the development of adjuvant arthritis which might render these rat strains relatively less susceptible to this disease.

Animals↗
PubMed1976

[Increase of brain serotonin and its metabolite in rats caused by meclofenoxate].

Influence of meclofenoxate (MF) on the 5-HT and 5-HIAA contents in the cortex, diencephalon and brain stem of the rat was studied with the following results. MF caused a dose-dependent elevation of 5-HIAA level in the three different brain regions and particularly in the brain stem. An increase of 5-HT was also noted in the brain stem, whereas 5-HT in the diencephalon tended to decrease. The increase of 5-HT after pargyline was accelerated and the pargyline-induced decrease of 5-HIAA was equally inhibited by MF and probenecid, which suggests that MF blocks the efflux of 5-HIAA from the brain. The effects of MF on the brain 5-HT and 5-HIAA contents were identical with those of its hydrolysate, p-chlorophenoxyacetic acid.

Animals↗
PubMed1975

Ultrasonographic determination of the splenic size and its clinical usefulness in various liver diseases.

Contact ultrasonic tomography was employed to obtain the size of the spleen in vivo. The scanning was done parallel to the ribs, and the splenotomograms obtained by this method showed three basic patterns of enlargement: a soft, bulging spleen, splenic congestion, or a firm spleen. Of the 96 patients with liver disease studied by this technique, 95% gave evidence of splenic enlargement. Useful information on prognosis may be obtained by observing the changes in the sectional areas of the spleen.

Acute Disease↗
PubMed1975

Correlation between brain monoamine levels and postictal coma following electroshock.

Duration of postictal coma following maximal electroshock seizure and monoamine levels in the whole brain were measured in mice. Pretreatment with intraperitoneal alpha-methyl-p-tyrosine (alpha-MT), 5-hydroxytryptophane (5-HTP), or intraventricular 6-hydroxydopamine (6-OHDA) prolonged the coma duration, whereas p-chlorophenylalanine (PCPA) did not affect the coma, and L-DOPA tended to shorten the coma and counteracted the effect of alpha-MT. When the shock was repeated five times with one hour intervals, the duration of coma was progressively increased being accompanied by elevated serotonin (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) levels in the brain. In alpha-MT treated group, a striking parallelism was remarked between coma prolongation and norepinephrine (NE) or dopamine (DA) reduction. These data suggest that prolongation of postictal coma is correlated with reduced NE and DA levels and/or with elevated 5-HT and 5-HIAA levels in the brain.

Animals↗
PubMed1975

The adjuvant activity of a non-toxic, water-soluble glycopeptide present in large quantities in the culture filtrate of Mycobacterium tuberculosis strain DT.

A water-soluble mycobacterial glycopeptide was obtained in large quantities from the culture supernatant fluid of M. tuberculosis strain DT. This glycopeptide was strongly adjuvant-active when injected, in a water-in-oil emulsion contianing ovalbumin, into guinea-pigs. In addition, it was devoid of cord factor toxicity in mice, polyarthritogenic activity in rats and cavity stimulating activity in rabbit lungs.

Adjuvants, Immunologic↗