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Biomedical subjects

A Kitamura

Publications and source records attributed to A Kitamura.

At least 163 records · Page 9Linked to original sources
PubMed1984

Detection of early gastric cancer by panendoscopy.

With the implementation of a small-caliber panendoscope which was made according to our suggestion, we gradually replaced the conventional barium meal as the first line of the upper gastrointestinal tract examination by panendoscopy after 1976. The efficacy of panendoscopy for the early detection of gastric cancer in our 8-yr experience was investigated. In 910 matched pairs of patients subjected to "screening" fluoroscopy or panendoscopy two and six cases of early gastric cancer were detected respectively. Panendoscopy was superior to fluoroscopy in its sensitivity for detection of gastric cancer (86.4% vs. 80.0%), in its specificity (99.5% vs. 97.0%) and in its low false-positive rate (17.4% vs. 69.2%). After 1976, the detection of early gastric cancer increased year by year. The frequency of early gastric cancer detected by panendoscopy was about three times that of early gastric cancer detected by fluoroscopy (61.5% vs. 21.7% of all cancer). Early cancer located in the proximal third of the stomach and superficial esophageal cancer were detected only by panendoscopy. All gastric cancers that were overlooked by panendoscopy were in the gastric body. How to prevent such overlooking is discussed. In 24,000 panendoscopies we have encountered six complications (0.03%). The cost of panendoscopy and fluoroscopy is 6,500 yen and 11,000 yen respectively.

Adult↗
PubMed1983

Effects of protease inhibitors on early events in the conjugation of paramecium caudatum.

The effects of 11 different protease inhibitors on mating reactivity and pair formation in the conjugation process of the ciliated protozoan Paramecium caudatum were investigated. Of the 11 inhibitors tested, six microbial and three synthetic inhibitors showed no effect on either pair formation or mating reactivity even at their highest concentrations. Soybean trypsin inhibitor and ovomucoid also showed no effect on pair formation even though they temporarily repressed mating reactivity. These results indicate that the process of pair formation during the conjugation process does not involve an extracellular proteolytic reaction.

Animals↗
PubMed1983

Micelle formation of diacylglycerophosphocholines in organic solvents I. Effects of the solvents on Krafft points.

Krafft points of diacylglycerophosphocholines (PC) were measured in alkanes-cyclohexane solutions by differential scanning calorimetry, and it was found that they were regularly increased following the increase in alkane content in the solutions and the chain length of the alkanes. From these results it was deduced that the mixing of PC with alkanes occurred in the gel state of the PC, but not in micelles at higher temperatures above the Krafft points, where micellar solutions are provided. The penetration of alkanes into gel state PC was found to be dominated by Langmuir type interaction, and the affinity of alkanes increases with increasing in chain lengths. Above the Krafft points, the micelle formation was confirmed by using the fluorescence probe technique.

Calorimetry, Differential Scanning↗
PubMed1983

Attachment of Paramecium to polystyrene surfaces. II. Induction of the attachment by hydrophobic reagents or immune immunoglobulin G.

Mating-reactive cells of Paramecium multimicronucleatum attach to a polystyrene surface (Falcon 10070 culture dishes) irrespective of extracellular ion concentration and swimming velocity. This attachment is induced in cells that are not mating-reactive by treatment with purified immunoglobulin G from antiserum, which blocks cells from mating or from antiserum prepared against the surface-localized immobilization antigens. Treatment with certain hydrophobic reagents such as phenethylamine, benzylamine, amphetamine or phenylethylamine also strongly induces attachment. Similar results are obtained with P. caudatum. Micronuclear activation, which normally occurs in the conjugation process, does not occur, however, in cells that are induced to attach to the polystyrene surface.

Adhesiveness↗
PubMed1982

Avian sarcoma virus Y73 genome sequence and structural similarity of its transforming gene product to that of Rous sarcoma virus.

From the complete nucleotide sequence of the genome of the avian sarcoma virus Y73, we have predicted amino acid sequence of p90 gag-yes, the product of the transforming gene. Contrary to previous evidence from molecular hybridization studies p90 gag-yes was found to have much homology with the transforming gene product p60 src of Rous sarcoma virus, suggesting that the cellular counterparts of the two (c-yes and c-src) originated from a common prototype sequence.

Alpharetrovirus↗
PubMed1982

Attachment of Paramecium to polystyrene surfaces: a model system for the analysis of sexual cell recognition and nuclear activation.

In the ciliate Paramecium caudatum, only mating-reactive cells can attach to the polystyrene surface of Petri dishes. The attachment of mating-reactive cells occurs exclusively at the tips of ventrally located cilia (mating-reactive cilia) and appears to involve a hydrophobic interaction. An increase in the hydrophilic nature of the polystyrene surface following treatment with sulphuric acid results in the loss of attachment of reactive cells. The presence or absence of Ca ions and varying the ionic strength of the medium have no effect upon attachment. Although attachment reactivity is closely correlated with mating reactivity, the attachment sites appear distinct from the mating recognition sites, as suggested by the following experimental results: (I) cells that lose mating reactivity following treatment with trypsin are still able to attach to the polystyrene surface; (2) the attachment of cells appears temperature-dependent over a range where mating reactivity remains uneffected; (3) mating reactivity is quickly lost as a result of attachment to the surface of the dish. While the mechanism of attachment is not the same as sexual recognition, the attachment to the polystyrene surface initiates the early stages of the conjugation process. Cells that attach show micronuclear migration while unattached cells do not. The maximum rate of micronuclear migration occurs approximately 30 min after attachment. Meiosis does not occur following migration in the attached cells as in cells that are sexually mating. The relationship between the mating substance and the attachment substance is discussed, while the utilization of the attachment phenomenon for other experimental procedures is proposed.

Animals↗
PubMed1981

Theophylline reduces poly (ADP-ribose) synthetase from chick embryo liver nuclei.

The effect of theophylline on poly(ADP-ribosyl)ation was investigated. The poly(ADP-ribose) synthetase activity in vitro was markedly reduced in the liver nuclei prepared from theophylline-treated chick embryo. This reduction was not due to the enzyme inhibition by theophylline contamination in the nuclear fraction. The hydroxyapatite column chromatographic analysis of [3H]adenosine-labelled poly(ADP-ribose)molecules formed in vivo revealed that the in vivo formation of poly(ADP-ribose)molecules was also decreased by theophylline administration. The theophylline-induced reduction of poly(ADP-ribose) synthesis was not due to either low NAD levels or to a decrease in the chain length of the poly(ADP-ribose) molecule, rather this reduction was derived from a decrease in the number of poly(ADP-ribose) molecule. Possible mechanisms related to reduction of poly(ADP-ribose) synthesis in vivo are discussed.

Animals↗
PubMed1981

Effect of polyamines on purified poly(ADP-ribose) synthetase from rat liver nuclei.

Using the purified enzyme system, we investigated the spermine-induced stimulation of poly(ADP-ribose) formation. In the presence of 2 microgram DNA and 10 mM Mg2+ in a reaction mixture of 0.2 ml, the optimal concentrations of spermine, spermidine and putrescine were 10, 12.5 and 35 mM, respectively. With the omission of Mg2+, there was an increase in optimal concentrations of polyamines without changes in the rate of poly(ADP-ribose) formation. The concentrations of spermine required for maximum synthesis of poly(ADP-ribose) were increased in proportion to the increase in the amount of DNA. Kinetic analysis of poly(ADP-ribose) formation showed a decrease in Km values for NAD with the addition of spermine. The possible relationship of polyions with regard to DNA, spermine and histone in the purified enzyme system was discussed.

Animals↗