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Biomedical subjects

K Iwata

Publications and source records attributed to K Iwata.

At least 451 records · Page 25Linked to original sources
PubMed1979

Adult T-cell leukemia with generalized cytomegalic inclusion disease and pneumocystis carinii pneumonia.

An autopsy case of adult T-cell leukemia with generalized cytomegalic inclusion disease and pneumocystis carinii pneumonia is reported. Tumor cells had T-cell characteristics (E-rosette) and cerebriform nucleus similar to Sèzary cells. Generalized lymphadenopathy, hepatosplenomegaly and an ectopic pancreas in the ileum were found at the time of autopsy. Histologically, leukemic infiltration was observed in almost every organ, and perivascular infiltration, vascular invasion were conspicuous findings. Cytomegalic inclusion bodies were observed in most organs (lungs, salivary glands, pancreas, liver, ectopic pancreas, sweat gland, stomach, thyroid gland, pituitary body, etc.). An acute hepatitis, probably caused by cytomegalovirus, was also noted. Presumed correlation of adult T-cell leukemia, cutaneous T-cell lymphoma and T-cell lymphoma was discussed.

Adult↗
PubMed1979

Effect of fatty acyl group and sterol composition on sensitivity of lecithin liposomes to imidazole antimycotics.

The specific affinity for membrane lipids and the membrane selectivity of three imidazole derivatives, clotrimazole, miconazole, and econazole, were studied using various types of liposomes with respect to the lecithin fatty acyl group composition and the liposome content and composition of sterol as membrane models. The sensitivity of liposomes to these drugs was primarily dependent upon the lecithin fatty acyl group composition. With sterol-free liposome systems, each imidazole induced maximum release of trapped glucose as a marker from the unsaturated dioleoyl lecithin liposomes, minimum release from the saturated dipalmitoyl lecithin liposomes, and intermediate release from egg lecithin liposomes. The sensitivity of the dipalmitoyl lecithin liposomes to any imidazole drug was not influenced by the incorporation of cholesterol or ergosterol. On the other hand, clotrimazole-induced permeability changes of liposomes prepared from unsaturated dioleoyl lecithin or egg lecithin were greatly enhanced by the incorporation of ergosterol, whereas they were suppressed by cholesterol incorporation. The sensitivity of liposomes prepared from these unsaturated lecithins to miconazole and econazole was also augmented by ergosterol incorporation, although it was scarcely altered by cholesterol incorporation. Negatively charged liposomes were more sensitive to the three imidazole drugs than positively charged liposomes.

Antifungal Agents↗
PubMed1978

Fungal toxins as a parasitic factor responsible for the establishment of fungal infections.

Although the mechanism of fungal infections, particularly that of opportunistic fungus infections, has been studied extensively, much still remains to be clarified. As is the case of certain bacterial infections, it has long been assumed by numerous investigators that some toxins, enzymes and other metabolites produced in vitro as well as in vivo by pathogenic fungi or their cellular constituents might be responsible for the establishment of fungal infections. However, there are very few papers which deal with isolation and/or characterization of pathogenic fungus-derived toxins, particularly those of high molecular weight, to sufficiently meet various criteria for toxins including etiopathological ability. Likewise, it has been speculated that certain enzymes produced by pathogenic fungi are related to the pathogenesis of infections with the fungi implicated, but no direct evidence has been provided. It is commonly held by researchers concerned with medical mycology that the lowering of specific and/or nonspecific resistance of a host to pathogenic fungi is a prerequisite for the establishment of infections, particularly opportunistic infections. However, it is also accepted that if a given fungus possesses no parasite factors (e.g. toxigenicity, invasiveness and others), it would be unable to initiate infection even when the host is in a severe immunodeficient state. This is supported by our recent studies working with Saccharomyces cerevisiae and some other so-called nonpathogenic yeasts (unpublished data). Based on these considerations, the author and his co-workers have attempted to isolate several high and low molecular weight toxins in a pure state from virulent strains of Candida albicans and Aspergillus fumigatus as opportunist. Studies have also been made on the etiopathological roles of some successfully isolated toxins in infections with the fungi implicated (46). In addition to our experimental results, general concepts in fungal toxins, particularly those related to such toxins as isolated in our laboratory are outlined. Since opportunistic fungus infections have created a global problem because of their world-wide prevalence, a sharp demarcation between the so-called pathogenic and nonpathogenic fungi has become vague. Despite this situation, two terms are conventionally used throughout this paper.

Aspergillus fumigatus↗
PubMed1978

Interaction of Escherichia coli glutaminyl-tRNA synthesis with noncognate tRNA's.

Several noncognate tRNA's from Escherichia coli were mischarged with glutamine by E. coli glutaminyl-tRNA synthetase if dimethylsulfoxide was present in the reaction mixture. Kinetic analysis of the mischarging revealed that dimethyl sulfoxide stimulated the misacylation by affecting the maximum velocity. Several noncognate tRNA's were shown to interact with glutaminyl-tRNA synthetase as measured by their ability to protect the enzyme against thermal inactivation or to replace cognate tRNA in stimulating glutamine-dependent ATP-PPi exchange reaction. These tRNA's, however, did not coincide with those which were mischargeable with glutamine.

Amino Acids↗
PubMed1978

Electron microscopic study on phagocytosis of staphylococci by mouse peritoneal macrophages.

Macrophages from the mouse peritoneal cavity were examined by electron microscopy at various time intervals up to 24 h after intraperitoneal administration of each of three strains of staphylococci different in virulence for mice: high-virulent, low-virulent, and avirulent strains. After engulfment, avirulent bacteria were highly liable to intracellular digestion, resulting in almost complete degradation within 24 h after injection, whereas high-virulent bacteria were more resistant to digestion, some showing figures suggestive of a dividing process; the gross configuration of most of the ingested bacteria was relatively well preserved over the 24-h period. Time-dependent morphological changes of low-virulent bacteria were intermediate. Among the most distinct cytoplasmic responses to the ingested bacteria was the formation of phagocytic vacuoles around them, the type of which was dependent on the staphylococcal strain infected; ingestion of avirulent bacteria led to formation of vacuoles in which the bacteria were surrounded by a halo of amorphous material of moderate density, which may be the lysosomal content. In contrast, larger vacuoles developed after ingestion of high-virulent bacteria and contained only a small quantity of such amorphous materials. Both types of phagocytic vacuoles were seen around the low-virulent bacteria ingested. Some degenerative changes were found in the macrophages ingesting high- or low-virulent bacteria, but were not in those ingesting avirulent bacteria. Thus, resistance to intracellular degradation, as well as cytotoxicity toward phagocytes of staphylococcal strains, can be correlated with their virulence.

Animals↗
PubMed1978

Mode of action of 6-cyclohexyl-1-hydroxy-4-methyl-2(1H)-pyridone ethanolamine salt (Hoe 296).

Mode of action studies were made with Hoe 296, a new synthetic antimycotic, mainly in Candida albicans. The specific parameters examined included possible effects on (i) osmotic fragility, (ii) respiration, (iii) uptake and incorporation of radioactive leucine and adenine, and (iv) leakage or efflux of intracellular K+ and other materials. As a result, fungitoxic activity of Hoe 296 appears to be attributed to inhibition of uptake of precursors of macromolecular syntheses from the medium. Uptake and accumulation of leucine in the internal pool of starved cells was more susceptible to the drug than subsequent incorporation into proteins. Hoe 296 was also effective in altering the cell permeability, but greater drug concentrations were required to induce appreciable leakage of cellular constituents, such as 260 nm-absorbing materials, folin-positive substances and potassium ions, from the cells. Osmotic fragility or endogenous respiration was virtually insensitive to the drug. Partial inhibition by relatively high concentrations of Hoe 296 of the respiratory activity of yeast cells or mitochondria therefrom with exogenous substrates can be explained by decreased uptake of the substrates from the medium.

Adenine↗
PubMed1977

Intra-axonal corpora amylacea in the CNS.

The distribution of intra-axonal corpora amylacea (IACA) in the CNS was studied in 2 cases of ALS, a hepatic encephalopathy and a Shy-Drager syndrome. A total of 149 IACAs were found. IACAs were observed far most frequently in the gracile nuclei, followed by the anterior horns of the spinal cord and in descending order; lateral geniculate bodies, reticular formation, sensory and motor nuclei in the brain stem, cerebellum and cerebral cortex. The basal ganglia, including the thalamus, contained only a few. IACA were not observed in the pyramidal tracts or in the spinal roots. About 3% of the IACA were sectioned longitudinally, together with the original small nerve fibres and abrupt enlargement of the axons due to the deposits was well demonstrated.

Amyloid↗
PubMed1977

Granule-bound tyrosinase: solubilization and its relation to the soluble form of tyrosinase.

Disc gel electrophoresis of tyrosinase solubilized by sodium deoxycholate (DOC) from the particle fraction of B16 mouse melanoma was carried out in the presence of DOC. A single tyrosinase band, considered to be T3, was detected at the Rx value of 0.60 against Coomassie brilliant blue. The T3 band which is located between T1 and T2 seems to be distinct from the soluble forms of tyrosinase. Its molecular weight was estimated to be 102,000. When treated with proteolytic enzymes or refrigerated, the T3 molecule converted into a molecule whose mobility was equivalent tothat of T1.

Animals↗