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Biomedical subjects

Y Hotta

Publications and source records attributed to Y Hotta.

At least 217 records · Page 12Linked to original sources
PubMed1985

Evidence that arachidonic acid is deficient in phosphatidylinositol of Drosophila heads.

We have found that arachidonic (20 : 4) acid is indetectable in phosphatidylinositol and diacyglycerol extracted from Drosophila heads. After careful examinations of the lipid extraction processes and fatty acid detection system (gas-liquid chromatography), we excluded the possibility of the oxidation of polyunsaturated fatty acids or of having overlooked a trace amount of the fatty acid. The precursors of arachidonic, dihomo gamma-linolenic (20 : 3), and gamma-linolenic (18 : 3) acid, were also indetectable in these lipids. On the basis of these results, it appears that the arachidonic acid cascade is essentially absent in Drosophila head, including the brain and compound eyes. Since arachidonic acid is considered to be a key molecule in phosphatidylinositol turnover in the brain, it is of interest that Drosophila brain and eyes do not require arachidonic acid for their functions.

Animals↗
PubMed1985

[Anatomical study of the yellow ligament of the spine with special reference to its ossification].

In thoracolumbar spine, the interlaminar and the capsular portion of the yellow ligament differed in their location and direction of elastic fibers. However, the capsular portion in most cervical spines were not considered to represent elastic tissues. At the ligament-osseous junction (enthesis) in the thoracolumbar spine, decreased elastic fibers, hyalinized collagen fibers, emergence of fibrocartilaginoid cells and intra-ligamentous calcification were noted. In the cervical spine and in part of the thoracolumbar spin, however, elastic fibers were close to the bony tissue partially penetrating it without the above-mentioned histological findings. Small ossification in the yellow ligament of a cadaver was considered to be "degenerative enthesopathy (enthesophyte)" originating from "enthesis". But in operative cases, the ossification had the same direction and location as those of the small ossification seen in a cadaver, but endogenous factors were strongly suggested because of the extensive change in matrix prior to ossification.

Adult↗
PubMed1985

[The natural course of osteoarthritis of the hip. Indication of conservative treatment in relation to osteophyte formation at the acetabular rim].

One hundred and eighty-five hips from 152 patients with primary or secondary osteoarthritis were studied in an attempt to assess the degrees of hip pain in contrast to radiological and other clinical findings. In 30.8% and 26.4% of the primary and secondary osteoarthritic hips respectively, hip pain showed some gradual decrease as time elapsed. Pain relief probably in association with osteophyte formation at the craniolateral acetabular rim occurred in 62.5% and 33.3% of the primary and secondary osteoarthritic hips respectively. Significant parameters observed in the primary osteoarthritic cases of the decreasing pain group were as follows: A lesser extent of cranial displacement of the femoral head, poor capital drop development, well developed floor osteophyte. On the other hand significant parameters in the decreasing pain group of secondary osteoarthritis were as follows: Well developed floor osteophyte, a small size of cyst in both the femoral head and the acetabulum, few "b" or "d" type of bony sclerosis in the acetabulum. Careful observation of radiographic changes (cyst and sourcil) would be most important, especially in secondary osteoarthritis, to decide the indication of surgery. On the basis of histological studies of osteophyte at the craniolateral acetabular rim obtained at the operation, it was assumed that the osteophyte formation had initiated from metaplasia of the labrum or synovial membrane and progressed by a form of chondral ossification after the process of fibrous tissue formation. A well developed trabecular density in the osteophyte at the craniolateral acetabular rim was determined by the use of Muto digigrammer system, Model G-002.

Acetabulum↗
PubMed1984

Absence of diglyceride kinase activity in the photoreceptor cells of Drosophila mutants.

Diglyceride kinase (DG) activity was found to be almost absent in the photoreceptor cells of Drosophila vision mutants, norpA (no receptor potential A). Other enzymes related to the phosphatidic acid (PA) metabolism, such as monoacyl-glycerophosphate acyltransferase and PA phosphatase, were normal in the mutant. The deficiency in PA content in the retinular cells of norpA, demonstrated by 32P incorporation in vivo is, therefore, due to abnormal reduction in DG kinase activity. The DG kinase was found to be localized in the retinular cell by assaying its activity in the mutants rdgA (receptor cells degenerated) and sine oculis (compound eyes absent).

Animals↗
PubMed1984

Replication and nicking of zygotene DNA sequences. Control by a meiosis-specific protein.

A protein having a molecular weight of 73,000 daltons has been purified from the nuclear membranes of preleptotene, leptotene, and zygotene cells. It has been named the leptotene protein (L-protein) because of its role in suppressing the replication of zygotene DNA sequences through leptotene until the initiation of zygotene DNA synthesis. The protein has been found to be highly specific in its inhibitory activity. S-phase replication in somatic nuclei and in microspore nuclei are unaffected by the protein. Only zygotene DNA sequences appear to be affected. L-protein binds specifically to zygotene DNA. The binding is limited to a relatively short DNA segment, probably no longer than 90 base pairs (bp). Chloroplast and mitochondrial DNA do not bind to the protein, but a low level of binding is displayed by DNA from several other eukaryotic species. The L-protein also has the capacity to nick the bound DNA in the presence of ATP. Nicking does not occur in the absence of binding. Using supercoiled plasmids with zygotene DNA inserts as substrates, the nicking has been found to be confined to a small region of the plasmid and to occur in only one of the strands. The L-protein is considered to be one of the principal factors responsible for the irreversible commitment of cells to meiosis at the end of the preleptotene S-phase. It is also proposed that its endonucleolytic activity plays a role in the initiation of synapsis.

Cell Cycle Proteins↗
PubMed1984

Relationship between the inotropy speeds in guinea-pig myocardium and lipophilic character of cardenolides and ericaceous toxins.

Interrelation between lipophilic characters and speeds of positive inotropic effect (PIE) of cardenolides and ericaceous toxins was studied by determining both parameters of lipophilicity and inotropy speeds. The lipophilic characters of 8 kinds of cardenolides, evaluated from Rm or log k' values by means of thin layer chromatography (Rf) or high performance liquid chromatography (retention time), increased in the order of ouabain, digoxin, digitoxigenin, digitoxigenin-monodigitoxoside, digitoxigenin-bis-digitoxoside, digitoxin, alpha-acetyl-digitoxin, triacetyl-digitoxin. Lipophilic character, evaluated from Rm values of 6 kinds of ericaceous toxins, was in decreasing order of 10S-grayanotoxin II, 6-acetyl grayanotoxin I, asebotoxin I, grayanotoxin I, asebotoxin III, asebotoxin X. The speed with which PIE developed was evaluated from the time to half maximum PIE (T50) of cardenolides and ericaceous toxins at a pD2 concentration. The speed of positive inotropy of cardenolides was independent of their concentration tested in the range from half to twice the concentration of pD2, while the speeds of PIE of ericaceous toxins depended on their concentration in the same range used in case of cardenolides. Inotropy speed of these two classes of cardiotoxins correlated well with the lipophilic character: a) In the case of cardenolides, a positive and close correlation (r = 0.98) was observed between T50 and Rm. The more lipophilic the cardenolides, the more time was required to reach the fully development of PIE. b) In contrast, a negative correlation (r = -0.82, between Rm and T50) was obtained in the case of ericaceous toxins; Toxins with more lipophilic nature caused faster development of PIE. The present results can be interpreted to mean that the PIE receptor for cardenolides in myocardial cells is located on the outer surface of the sarcolemma, while that for ericaceous toxins is located on the inside of the myocardial cell.

Animals↗
PubMed1984

Construction of plasmid vectors from Streptomyces kasugaensis plasmids, pSK1 and pSK2.

Streptomyces kasugaensis G3 was transformed by pIJ702 DNA carrying the thiostrepton-resistance gene at a frequency of 2 X 10(5) transformants/micrograms DNA, but it was found that the introduced pIJ702 was very unstable in this strain. This result led us to make useful vectors using the stable plasmids resident in S. kasugaensis. The Bcl I-fragment, containing the thiostrepton-resistance gene obtained from pIJ702, was inserted into the pSK1 and pSK2 plasmids isolated from S. kasugaensis. Two composite plasmids, pSK11-1 (8.0 Md) and pSK21-1 (4.8 Md), were isolated from the thiostrepton-resistant transformants of strain Ge. The constructed pSK11-1 consisted of the entire pSK1 molecule and the thiostrepton-resistance gene fragment. pSK21-1 consisted of the large Bcl I-fragment of pSK2 (4.1 Md) and the same thiostrepton-resistance gene. These plasmids were stably maintained in S. kasugaensis G3. Small derivatives of these composite plasmids were prepared by restriction enzyme cleavage and self-ligation, and several unique insertion sites were also constructed in these small plasmids. By analysis of the physical maps of these plasmids, the essential regions of pSK1 and pSK2 were determined from their DNA segments to be 2.5 Md in pSK11-1 and 1.9 Md in pSK21-1. pSK21-B5, one of these plasmid vectors, showed a wide host range in the genus Streptomyces and was stably maintained in all streptomycete species tested, except S. kasugaensis M338.

Genetic Vectors↗
PubMed1984

Chromosome organization in the regulation of meiotic prophase.

The prophase stages of meiosis, particularly zygotene and pachytene, are organized to sustain the events required for recombination between homologous chromosomes. Three categories of DNA sequences are believed to function in the control of these events. One category comprises the sites of transcription for meiosis-specific proteins. The other two categories are related to the structural organization of chromosomes at meiotic prophase. Sequences that are delayed in replication until zygotene may provide the sites for chromosome alignment in securing the synapsis of homologues. General chromosome synapsis is presumed to be functionally distinct from the synapsis of DNA strands that occurs in localized regions at which recombination may take place. Recombinational synapsis probably involves families of moderately repeated sequences, here designated as PDNA. PDNA segments have a compound organization. Each of their ends is occupied by a moderately repeated sequence that belongs to one of several hundred families designated as 'PsnDNA'. The latter range from 150-300 bp in length and do not hybridize with the internal PDNA regions. PsnDNA sequences are the sites at which most of the programmed nicking, gapping and repair syntheses occur during pachytene. They are also the sites at which histones are displaced by a meiotic prophase-specific protein that somehow renders the PsnDNA accessible to the action of meiotic endonuclease. This structural change in the chromatin is partly controlled by a meiosis-specific small nuclear RNA (PsnRNA) that is homologous with PsnDNA and also has a specific affinity for the histone-replacing protein. The complex of events associated with the transformation in PsnDNA chromatin regions is also subject to control by homologous chromosome pairing.

Base Sequence↗
PubMed1983

Defective phospholipid metabolism in the retinular cell membrane of norpA (no receptor potential) visual transduction mutants of Drosophila.

The phosphorylation of photoreceptor phospholipids in the three alleles of Drosophila visual mutants (norpA: no receptor potential A gene) was studied. In the normal strain, the gamma-32P of ATP was transferred mainly to phosphatidic acid (PA) and diphosphoinositide (DPI), while, in the mutants, we found that the phosphorylation of PA was drastically reduced, but that of DPI was not. The radioactivity incorporation into PA closely parallels with the degree of the mutant genes' expressivity among the three alleles of norpA tested. Therefore, the abnormality found in the phosphorylation of diglycerol to PA may be closely related to the primary mutant defect in the phototransduction mechanism.

Alleles↗
PubMed1983

Quantitative structure-inotropy relationship applied to substituted grayanotoxins.

Nine 14 beta-O-acylated grayanotoxins were synthesized by ozonolysis of 14,16-alkylidenegrayanotoxin III. The correlation between positive inotropic potency (PIE) in guinea pigs and physicochemical parameters (Vw, Mw, and Rm50) in 14 14-substituted grayanotoxins were quantitatively analyzed. It became clear that a parabolic relation existed between the bulkiness of the 14-substituents and PIE and that some electronic factor and the hydrophilic-hydrophobic balance would be related to the development of PIE.

Animals↗
PubMed1983

Electron microscopic study on the floating lipids of human liver. Lysosomal involvement in the fatty liver associated with diabetes mellitus.

Using fractionation, subcellular pathogenesis of the fatty liver was investigated. Floating lipids were isolated from a small amount of the liver obtained by needle biopsy. The volume of the floating lipids was correlated to the grading of fat infiltration of the intact tissue. Of lipid-rich particles bound by membranous structures, the volume of lipolysosomes in the patients with liver damage associated with diabetes mellitus was greater than that of alcoholics. Hypercholesterolemia was another feature characteristic of the liver disease exhibiting lipolysosome proliferation. These observations suggest a lysosomal involvement in fatty degeneration of the liver in diabetics through an overload of cholesterol.

Adult↗
PubMed1982

Identification of Drosophila indirect flight muscle myofibrillar proteins by means of two-dimensional electrophoresis.

When proteins of whole Drosophila thorax were analyzed by two-dimensional gel electrophoresis, 186 spots were detected by protein staining with Coomassie brilliant blue R-250. Two methods were developed to identify proteins which exist in indirect flight muscle (IFM) and its myofibrils. 1) A whole fly was freeze-dried in a dry ice-acetone mixture, and indirect flight muscle fibers were cleanly dissected out from the thorax. The muscle cells and the rest of the thorax were analyzed separately. The muscle contained 146 polypeptides, of which 12 were not detected elsewhere. 2) Flies were frozen in liquid nitrogen and shaken vigorously so that their thoraces broke off from heads and abdomens. The thoraces were separated from the rest by sieving and centrifugation. After homogenization of the thorax, myofibrils were prepared by centrifugation in a discontinuous sucrose density gradient. The myofibril fraction contained at least 20 proteins. There were two types of actin (II and III), myosin heavy chain, tropomyosin and paramyosin. Nine of the other myofibrillar proteins were specific to this muscle.

Animals↗
PubMed1982

Egg yolk-induced lipolysosome proliferation and fat infiltration of rat liver.

The contribution of subcellular organelles in egg yolk-induced fatty liver was investigated in liver tissue sections and fractionated liver homogenates. When 2.0 ml. of 12.5 per cent egg yolk were administered to Wistar male rats (body weight, 250 to 350 gm.), a fatty change occurred in the liver after a 4-hour period. The acute fatty liver was characterized by intralysosomal accumulations of fat. The number of fat-containing lysosomes increased as early as 30 minutes after egg yolk administration. During this period, fat infiltration was not evident elsewhere in the cytoplasm. The increase of these lysosomes in tissue sections coincided with a selective proliferation of lipolysosomes in the heavy subfraction of floating lipids of liver homogenate. Neither Golgi-derived dense bodies of very low density lipoproteins nor vesicles of the endoplasmic reticulum increased in number throughout the experimental period. These observations indicate that hepatic lysosomes are involved in the degradation of exogenous cholesterol and that transformation of lysosomes to lipolysosomes is a direct result of cholesterol overload and not simply a manifestation of fatty liver.

Animals↗
PubMed1981

Isolation of Drosophila flightless mutants which affect myofibrillar proteins of indirect flight muscle.

A large number of dominant flightless mutants of Drosophila were chemically induced, and their thorax proteins were examined by chemically induced, and their thorax proteins were examined by means of two-dimensional gel electrophoresis (O'Farrell 1975). Among them, 26 lines were found to have deficiency or reduction of some of myofibrillar proteins in indirect flight muscle (IFM). The gel patterns of the mutants could be classified into eleven groups. In general, more than a few polypeptides were either absent or reduced in each mutant line. Although the mutations affect myofibrillar proteins in apparently complex and diverse ways, logical correlations were found among the changes. There are pairs of proteins which always change together when a number of mutants are compared. There are also many pairs in which presence of one protein is necessary, but not sufficient for presence of the other. This suggests that absence of one component leads to disappearance or reduction of others which are either spatially or functionally related to the former. The correlation is possibly due to a hierarchy of the proteins in the myofibrillar assembly processes. Chromosomal loci of eleven typical mutants were examined, and it was found that most of them are located in two small regions of the second and the third chromosomes. IFM myofibrils of these mutants are either abnormal or absent in homozygotes as well as in heterozygotes.

Animals↗
PubMed1981

Small nuclear RNA molecules that regulate nuclease accessibility in specific chromatin regions of meiotic cells.

One of the factors regulating the accessibility of specific DNA sequences to endonuclease nicking during meiosis is a group of small nuclear RNA molecules, 125 nucleotides in length and transcribed by RNA polymerase III. These molecules (referred to as PsnRNA) are synthesized during meiotic prophase, when chromosomes are undergoing homologous pairing or are already paired. Accessibility to the meiotically active DNA sequences (P DNA) depends on an as-yet-undefined alteration in chromatin structure. PsnRNA is a critical factor in the alteration; it cannot be replaced by other forms of RNA. The specificity of the chromatin sites altered by PsnRNA appears to be a function of sequence complementarity between it and P DNA. Under in vivo conditions the effective action of PsnRNA depends on homologous chromosome pairing. Chromatin sites housing P-DNA sequences in nuclei isolated from cells lacking homologous pairing are not affected by meiotic endonuclease or DNAse II. Accessibility to these sites can be effected by incubation of the nuclei with PsnRNA, but only if the nuclei are from zygotene-pachytene cells. Analyses of pachytene nuclei preincubated with PsnRNA indicate that PsnRNA renders chromatin accessible to at least two endonucleases, meiotic endonuclease and DNAase II, and that it also limits such accessibility to regions housing the complementary P-DNA sequences.

Base Sequence↗