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Biomedical subjects

K Yamafuji

Publications and source records attributed to K Yamafuji.

At least 19 recordsLinked to original sources
PubMed2001

Fetal DNA diagnosis from maternal blood: PEP-TaqMan PCR analysis of a single nucleated erythrocyte (NRBC).

Development of a real-time quantitative TaqMan PCR assay permits the high-quality analysis of DNA or RNA. This study demonstrates the successful detection of single locus genes from single NRBCs, retrieved by micromanipulation of cells on a blood smear slide. Quantitative data in relation to the concentration of a single locus DNA amplified by PEP from a single NRBC are also provided. In summary, a PEP-TaqMan system can potentially be a powerful tool for noninvasive fetal DNA diagnosis through the use of maternal blood.

Cell Nucleus↗
PubMed2000

Successful treatment of recurrent liver metastases from gastric cancer by repeated hepatic resections: report of a case.

We describe herein the case of a patient in whom recurrent liver metastases from gastric cancer were successfully treated by performing repeated hepatic resections. A 63-year-old man underwent a total gastrectomy with regional lymph node dissection for an advanced gastric cancer on November 17, 1992, the pathological findings of which confirmed a diagnosis of well-differentiated tubular adenocarcinoma, ss, INFalpha, ly1, v0, n1(+). Follow-up computer tomography (CT) and ultrasonography scans done 7 months after the gastrectomy revealed a metastasis in the liver S5, and a partial resection of S5 was performed on July 5, 1993. Subsequently, on November 17, 1994, an anterior segmentectomy of the liver was performed for a liver metastasis in the liver S8, then on August 11, 1998, a partial resection of the liver S6 was performed for a metastasis in the liver S6. The pathological findings of each liver specimen resected were compatible with metastatic adenocarcinoma from the primary gastric cancer. The liver tumors were expansive-growing tumors with capsules and massive necrosis. The patient is currently well with no evidence of recurrence on repeat CT scans, 6 years 6 months since-the initial gastrectomy, and 5 years 10 months since the first hepatic resection.

Adenocarcinoma↗
PubMed1999

Cathepsin Y (a novel thiol enzyme) produces kinin potentiating peptide from the component protein of rat plasma.

Rat spleen cathepsin Y (a novel enzyme) that produces bradykinin (BK) potentiating peptide (BPP) from rat plasma was isolated, characterized and its amino acid sequence was deduced from cDNA cloned by reverse transcription-polymerase chain reaction (RT-PCR). We propose the name cathepsin Y for this enzyme considering its origin, characteristics and the amino acid sequence. BPP potentiates not only BK but also lysyl-BK (lysBK) and T-kinin (TK) action on uterus contraction. The structure of BPP is Pro-Pro-Pro-Leu-Gly-Pro-Gly-Ser. The magnitude of the potentiation of BK activity by synthesized BPP was seven-fold when equivalent quantities added to BK and 23-fold when the level is doubled. The precursor proteins that produce BPP by the action of cathepsin Y are eluted into two fractions when the heated plasma was applied to a negative ion exchange column. Structure relationships between these two proteins are now under investigation. In this paper, we report on the characteristics and the amino acid sequence of rat spleen cathepsin Y, its structure and the potentiating activity of BPP, and isolation of the precursor protein.

Amino Acid Sequence↗
PubMed1996

The thiol enzyme from rat spleen that produces bradykinin potentiating peptide from rat plasma.

We have focused our studies on a thiol-dependent enzyme of 37 kilodaltons (kDa) that produces a bradykinin (BK) potentiating peptide. The molecular mass of the peptide was estimated to be around 750 Da and its amino acid composition was Pro4 Gly2 Leu1 Ser1 with a proline and a serine at the N- and C-terminals, respectively. Biological activity was assayed by means of uterus contraction. The enzyme differs from Cathepsin L or B by virtue of its immunological reactivity and enzyme kinetics. The inhibitors used were leupeptin, antipain, E-64 and chymostatin in order of effectiveness. The low molecular SH reagents also diminished the enzyme activity. Among the metal ions tested, Cu2+ and Zn2+ inhibited the reaction.

Animals↗
PubMed1995

Development of non-invasive fetal DNA diagnosis from maternal blood.

Several attempts have been made to detect and retrieve fetal nucleated cells including nucleated erythrocytes (NRBCs), leukocytes, and trophoblasts in maternal blood. We have recently developed a new method for non-invasive fetal DNA diagnosis from maternal blood. Peripheral blood granulocytes including NRBCs were isolated by a discontinuous density gradient method using Percoll (Pharmasia). NRBCs were found and retrieved at a single cell level using a micromanipulator under a microscope. To determine whether the origin of the NRBCs was maternal or fetal, the NRBCs were analysed by polymerase chain reaction (PCR) amplification to determine the presence of a Y-chromosome-specific repeat sequence in mothers carrying male fetuses. We were successful in predicting fetal sex accurately in 10 out of 11 samples taken from maternal blood. This new technique opens up fetal DNA diagnosis from maternal blood during the first trimester of pregnancy to the whole population because there is no risk to the fetus or the mother.

Cell Nucleus↗
PubMed1995

Castleman's disease of the abdomen and pelvis: report of three cases and a review of the literature.

Three cases of Castleman's disease (CD) of the abdomen and pelvis are reported. Tumoral lesions were located in the lymph nodes of the head of the pancreas, the gastropancreatic fold, and around the left iliac artery. Histologically, all the tumoral lesions demonstrated the hyalinevascular type of CD. This unusual presentation made CD difficult to diagnose preoperatively, since these lesions more closely resembled malignant tumors on computed tomography and angiography. We discuss the problems of diagnosing and classifying CD, together with a review of the literature.

Abdomen↗
PubMed1994

Multichannel taste sensor using electric potential changes in lipid membranes.

A taste sensor with a multichannel electrode was developed by using lipid membranes as a transducer of taste substances. The sensor can detect the taste in a similar manner to the human gustatory sensation by response patterns of electric potential to taste substances. The sensitivity, reproducibility and durability were superior to those of humans. The same taste as that elicited by some commercial aqueous drink was reproduced by making aqueous solution mixed from four kinds of basic taste substances, the concentrations of which were determined so that the electric-potential pattern of this mixed solution could agree well with the pattern by the drink. Different brands of beer were easily distinguished by the electric-potential patterns.

Biosensing Techniques↗
PubMed1994

Responses of lipid membranes of taste sensor to astringent and pungent substances.

Astringent substances and pungent substances were studied using a multichannel taste sensor with lipid membranes. The electric-potential pattern constructed of eight outputs from the membranes has information of taste quality and intensity. Pungent substances, such as capsaicin, piperine and allyl isothiocyanate, had no effect on the membrane potentials of the lipid membranes. On the other hand, astringent substances such as tannic acid, catechin, gallic acid and chlorogenic acid changed the potentials remarkably. A principal component analysis of the patterns in electric potential changes caused by the taste substances revealed the astringency is located between bitterness and sourness.

Astringents↗
PubMed1992

Electric current precedes emergence of a lateral root in higher plants.

Stable electrochemical patterns appear spontaneously around roots of higher plants and are closely related to growth. An electric potential pattern accompanied by lateral root emergence was measured along the surface of the primary root of adzuki bean (Phaseolus angularis) over 21 h using a microelectrode manipulated by a newly developed apparatus. The electric potential became lower at the point where a lateral root emerged. This change preceded the emergence of the lateral root by about 10 h. A theory is presented for calculating two-dimensional patterns of electric potential and electric current density around the primary root (and a lateral root) using only data on the one-dimensional electric potential measured near the surface of the primary root. The development of the lateral root inside the primary root is associated with the influx of electric current of about 0.7 muA.cm(-2) at the surface.

Journal Article↗
PubMed1992

Isolation of a thiol-dependent acid kininogenase from rat spleen.

The enzyme which could produce kinin-like peptides from rat plasma at acidic condition and at coexistence of thiol compound was separated from acid extract of rat spleen. The isolation procedure of this enzyme was established. Substrate specificity was examined against fluologenic substrates and two types of collagen. The purified enzyme was proved to have kinin-forming activity and also collagenlytic activity.

Animals↗
PubMed1991

Electrical characteristics in an excitable element of lipid membrane.

Electrical characteristics in a membrane constructed from a porous filter adsorbed with a lipid analogue, dioleoyl phosphate (DOPH), were investigated in a situation interposed between 100 mM NaCl + 3 mM CaCl2 and 100 mM KCl. Calcium ions affected significantly the membrane characteristics. The membrane potential was negative on the KCl side, which implies the higher permeability to K+ than Na+; this tendency was increased by a tiny amount of Ca2+. While the membrane showed a low electrical resistance of several k omega . cm2 under K+/Na+ gradient, it showed several M omega . cm2 by Ca2+. The surface structure of the membrane exhibited many voids in the low-resistance state, but the surface was covered by oil droplets in the high-resistance state. Oscillations of the membrane potential appeared spontaneously with application of the electrical current from the KCl side to the NaCl + CaCl2 side. The frequency was increased with the electrical current. All these results were explained comprehensively using an electrochemical kinetic model taking account of the Ca2+ binding effect, where DOPH assemblies make a phase transition between oil droplets due to Ca2+ and multi-bilayers with excess K+. The oscillation arises from coupling of the phase transition to accumulation and release of K+ or Ca2+. This membrane can be used as an excitable element regulated by Ca2+ in neuro-computer devices.

Calcium↗
PubMed1991

Electrical Potentials during Gravitropism in Bean Epicotyls.

An apparatus for measuring simultaneously the surface electrical potentials along epicotyl was developed to study the largely bending situation by gravity. Potentials increased on the upper side and decreased on the lower side after the horizontal placement. The time course of electrical changes consisted of two components which correspond to growth movements observed during gravitropism.

Journal Article↗
PubMed1991

[Experimental study on carcinogenesis in the vagotomized stomach].

The susceptibility to cancer in the vagotomized stomach which was assigned either to selective vagotomy (SV) or selective proximal vagotomy (SPV) was studied by gastric carcinoma model of male Wistar rat on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) administration. Predilection for cancer of the remnant stomach was also studied. Four groups of the rats submitted to either one of the SV, SPV, antrectomy (Billroth-I reconstruction) or control (simple laparotomy) group, were prepared. The techniques of SV and SPV in rat was originally developed. MNNG in drinking water was given as carcinogen. Gastric acid output, gastric stasis, serum gastrin levels together with the number and the invasiveness of the atypical glands those were recognized in the glandular stomach of rats were examined. The results were as follows: (1) the reduction rate of gastric acid output was the most conspicuous at antrectomy group followed by SV and SPV groups, (2) gastric stasis was observed in almost the same degree in SV and SPV groups, (3) serum gastrin level was the highest in SV group followed by SPV, control and antrectomy groups in this order and (4) the susceptibility to malignancy was significantly high at SV group but not high at SPV and antrectomy group as compared with control group.

Animals↗
PubMed1990

Effect of local anesthetics on the electrical characteristics of an excitable model membrane composed of dioleyl phosphate I. Static and steady-state response.

The local anesthetics, tetracaine, procaine and lidocaine, interacted with a negatively charged lipid membrane composed of dioleyl phosphate (DOPH), which exhibited a self-sustained oscillation of the membrane potential. The anesthetics depolarized the membrane potential when present in increasing concentrations, whereas they increased the membrane resistance at low concentrations and decreased it at high concentrations. The above results were analyzed on the basis of electrochemical theory taking into account ion flux across the membrane. The electrical characteristics are affected by both the hydrophobicity and the diffusion constant of local anesthetics within the membrane.

Journal Article↗
PubMed1990

Effect of local anesthetics on the electrical characteristics of an excitable model membrane composed of dioleyl phosphate II. Dynamic response.

The effects of local anesthetics (tetracaine, procaine and lidocaine) on self-sustained electrical oscillations were studied for a lipid membrane comprising dioleyl phosphate (DOPH). This model membrane exhibits oscillation of the membrane potential in a manner similar to that of nerve membranes, i.e., repetitive firing, in the presence of an ion-concentration gradient, on the application of d.c. electric current. Relatively weak anesthetics such as procaine and lidocaine increased the frequency of self-sustained oscillation, and finally induced aperiodic, rapid oscillation. The strong anesthetic tetracaine inhibited oscillation.

Journal Article↗
PubMed1990

Relationship between Growth and Electric Oscillations in Bean Roots.

Extracellular and intracellular electric potentials in bean roots are known to show electric oscillations along the longitudinal axis with a period of several minutes. The relationship between growth and the electric oscillations was studied using roots of adzuki (Phaseolus chrysanthos). We measured surface electric potentials with a multielectrode apparatus while simultaneously measuring elongation using a CCD camera and monitor. Roots having an electric oscillation grew faster than roots with no oscillation. Furthermore, elongation rate was higher in roots with higher oscillation frequency. Oscillation frequency had a strong dependence on temperature; i.e. Q(10) was estimated at 1.7. These results suggest a correlation between electric oscillation and elongation.

Journal Article↗
PubMed1989

Growth and electric current loops in plants.

A theory is presented for a relationship between ion accumulation and electric current loops in multicellular systems such as the roots and stems of higher plants. A network of electric circuits shows that the electric current transported across the cell membrane flows between an elongating region and a mature region, not only in roots but also in stems. In roots, ions constituting the extracellular electric current flow in the external aqueous medium, while in stems an electric current of comparable density flows within the epidermal cell wall. Based on this theoretical result, electric isolation between the elongating and mature regions was made in the case of both roots and stems. The speed of growth during the initial stage was greatly decreased due to a change in the distribution of protons around the surfaces of the plant by cutting off the electric current loop. Electrochemical calculation shows that ions are not always accumulated at the efflux site, since the ion distribution is strongly affected by the relation of the magnitudes between the electric field and electric current. The results calculated for the electric potential and pH distributions around the root agree with experimental data.

Journal Article↗