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Biomedical subjects

T Yamane

Publications and source records attributed to T Yamane.

At least 271 records · Page 15Linked to original sources
PubMed1995

Rapid and accurate method for delineating cancer lesions in laparoscopic colectomy using activated carbon injection.

The aim of our study was to evaluate the clinical efficacy of preoperative injection of activated carbon in delineation of cancer location in laparoscopic colectomy. Activated carbon particles were injected during endoscopy into the normal colonic wall surrounding cancer lesions in five cases of early colon cancer, prior to laparoscopic surgery. The carbon-stained area was clearly recognizable as a blackened patch on the serosal surface of the colon. Using the carbon-stained area as a reference point, partial colectomies were successfully performed on all five patients. The preoperative injection of activated carbon assisted in the intraoperative delineation of early colonic cancer lesions. This method is recommended for the rapid and accurate delineation of early colonic cancers in laparoscopic surgery.

Aged↗
PubMed1995

Ultrastructural changes in the lung in Niemann-Pick type C mouse.

The biochemical and morphological aspects of BALB/c mice with many features of the Niemann-Pick disease type C in man (NP-C mouse) have been studied extensively. However, the pulmonary pathology has not been studied extensively and we describe here some unique ultrastructural features of the lung in the NP-C mouse. Ultrastructurally, macrophages in younger mice contained osmiophilic dense granules and annulolamellar structures, but larger multilamellar concentric structures increased in the macrophages of older mice. In contrast, endothelial cells and type I pneumocytes showed membrane-bound bodies with dense granules and vesicular or vesiculogranular structures as well as amorphous materials. Type II pneumocytes were unremarkable throughout. Our study suggests that endothelial cells and type I pneumocytes are the major site of metabolic derangement resulting in pronounced morphological changes with granular and round membranous structures in the lungs of NP-C mouse. Alveolar macrophages with multilamellar concentric structures may be a result of disturbed disposal of surfactant material from type II pneumocytes rather than that from storage material of type I pneumocyte.

Animals↗
PubMed1995

How safe are the xenogeneic hemostats?--Report of a case of severe systemic allergic reaction.

We report herein the unusual case of a 55-year-old woman who developed a severe systemic allergy to Avitene (microfibrillar collagen hydrochloride), a xenogeneic agent sometimes used for topical hemostasis in laparoscopic cholecystectomy. The patient developed fever, general fatigue, mild liver dysfunction, and prominent eosinophilia postoperatively. A skin allergy test confirmed that these abnormal findings were attributable to an allergic reaction to Avitene.

Abdominal Abscess↗
PubMed1995

Biochemical and pharmacological studies on a lethal neurotoxic polypeptide from Phoneutria nigriventer spider venom.

Fractionation of Phoneutria nigriventer spider venom by gel filtration and HPLC yielded a few fractions that induced different effects when administered intraperitoneally in mice. One of these fractions, PF3, was chemically characterized as a cysteine-rich polypeptide of approximately 8360 MW. Administered at 0.1 mg/kg, i.p., PF3 induced a progressive paralysis and death of mice within 30 minutes. Partial sequence analysis of PF3 revealed certain homologies with other spider toxins already described, particularly omega-AGAIIA (60%) from Agelenopsis aperta. Pharmacological characterization carried out in superfused chopped rat striatal tissues preloaded with [3H]-Dopamine ([3H]-DA) showed that PF3 (0.1 microgram/ml) decreased the [3H]-DA release induced by 20 mM K+ or 100 microM glutamate without changing the basal release. At 1 microgram/ml, PF3 inhibited 33% of the basal release of [3H]-DA; the transmitter release stimulated by K+ or by glutamate was reduced by respectively, 87% and 77% of corresponding control values. PF3 (0.1 micrograms/ml) altered the dose-response curves of glutamate (1 microM-10 mM), by reducing by 36% of its maximal effect. Naloxone (1 microM) did not influence the effect of PF3. The results indicate that PF3 inhibits the [3H]-DA release induced by membrane depolarization or that mediated by NMDA glutamate receptors. These data suggest that the mechanism of action of PF3 may involve a blockade of Ca2+ channels as well as a direct effect on the exocytotic machinery.

Animals↗
PubMed1995

Proliferative activity in breast carcinoma evaluated by BrdU and PCNA. Correlation with expression of p53, c-erbB-2, estrogen receptor and P-glycoprotein.

The proliferative activity in 35 cases of breast carcinoma was evaluated by bromodeoxyuridine (BrdU) and proliferating cell nuclear antigen (PCNA) and was compared with benign breast lesion. Overexpression of p53 and c-erbB-2 oncoprotein, presence of estrogen receptor (ER) and cellular localization of multidrug resistance gene product P-glycoprotein (P-gp) were immunohistochemically examined to investigate the relation with the proliferative activity and clinicopathologic characteristics. The mean BrdU labeling index (LI) was 12.6% and PCNA labeling rate (LR) was 33.5% in breast carcinomas, and good correlation was found between them. The proliferative activity of breast carcinomas was significantly higher than that of benign lesions. The BrdU LI correlated positively with tumor size, histologic grade, TNM stage and p53 immunoreactivity, and negatively with the presence of ER. PCNA LR correlated with histologic grade and expression of p53. p53 protein was demonstrated in 43% of the breast carcinomas and correlated with proliferative activity. The extent of p53 immunoreactivity on carcinoma cells was also related to BrdU LI. c-erbB-2 oncoprotein was demonstrated in 51% of the breast carcinomas and correlated with histologic grade. ER was found in 34% of the breast carcinomas and correlated negatively with histologic grade, lymph node metastasis and TNM stage. P-gp was observed in 49% of the breast carcinomas and no correlation was found with clinicopathologic characteristics. None of the benign lesions expressed p53 protein, c-erbB-2 oncoprotein and P-gp. BrdU is a reliable standard and a more useful tool for the evaluation of proliferative activity of breast tumors. High proliferative activity, overexpression of p53 protein and the absence of ER are considered as a high grade malignancy of breast carcinoma. Expression of c-erbB-2 oncoprotein and P-gp may be related to malignant transformation of breast tumors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Crystal structure of Streptomyces erythraeus trypsin at 1.9 A resolution.

A trypsin-like serine protease from Streptomyces erythraeus (abbreviated as SET) has been crystallized at pH 7, which is within its active pH range. The crystal structure of SET has been solved by molecular replacement using the atomic model of Streptomyces griseus trypsin (SGT), which is 37% homologous with SET, and refined to the crystallographic R factor of 0.199 for 15,878 reflections with Fo/sigma(F) > 3 between 7 and 1.9 A resolution. The final model of SET contains 1,619 protein atoms and 97 water molecules. No Ca2+ ion is present in SET apparently because (i) the two carboxylate groups from two Glu residues, which bind a Ca2+ ion in bovine trypsin (BT) or SGT, have disappeared; and (ii) a guanidino group from an Arg residue is unfavorably present in the potential binding region. There is an unusual type II beta-turn in which the third residue is Asp instead of Gly. This Asp residue is the only non-Gly residue significantly outside the allowed regions in the Ramachandran map. The three-dimensional structure of SET is essentially the same as those of other trypsins of mammalian origin. The 211 C alpha atoms of SET exhibit an r.m.s. deviation of 1.16 A with equivalent atoms of BT, and the 208 equivalent C alpha atoms between SET and SGT exhibit an r.m.s. deviation of 1.09 A. The large deviations in C alpha positions between SET and BT or between SET and SGT are mainly observed in the first domain. The conformations of the side-chains of the catalytic triad are mutually similar to each other in these three proteases. Each of the chi 1 torsion angles of the three residues is distributed within +/- 5 degrees from each corresponding mean value. The hydrogen bond distances related to the side-chains in the triad coincide fairly well, though the relative disposition of the side-chains differs by 0.1-0.6 A among SET, BT, and SGT. The hydrogen bond network concerned with Ser(195), Asp(189), and water molecules in the substrate binding pocket differs from that in BT or SGT.

Amino Acid Sequence↗
PubMed1995

Crystal structure analysis of phospholipase A2 from trimeresurus flavoviridis (Habu snake) venom at 1.5 A resolution.

The crystal structure of dimeric phospholipase A2 (PLA2) from the venom of Habu snake, Trimeresurus flavoviridis, has been determined by the molecular replacement method, and has been refined at 1.5 A resolution to an R-factor of 0.175. In the crystal, T. flavoviridis PLA2 forms a dimer using two 14 kDa subunits related by a pseudo 2-fold axis. Along the axis, the dimer has a narrow channel passing through it. Although no calcium ion is present in the calcium binding site, the peptide-chain folding of the subunits, the conformation of the catalytic residues, and the hydrogen-bonding network around the active sites are almost identical to those of the group I/II monomeric or dimeric PLA2s. The catalytic residues in both subunits are buried in the interior of the dimer and are inaccessible to substrate from the bulk solvent. In addition, the subunits of the dimer interact with each other at the hydrophobic region of the molecular surface where the entrance to the active site opens and where PLA2 is presumed to interact with the phospholipid of the substrate. Therefore, it is inferred that dimerization of T. flavoviridis PLA2 is the result of free-energy minimization by excluding the hydrophobic molecular surface from the aqueous solvent, rather than being required for the enzymatic function.

Amino Acid Sequence↗
PubMed1995

Inhibition of 1,2-dimethylhydrazine-induced oxidative DNA damage by green tea extract in rat.

Following subcutaneous injection of 1,2-dimethylhydrazine (DMH), which is carcinogenic to rat colon and liver, to Sprague-Dawley rats, a significant increase of 8-hydroxydeoxyguanosine (8-OHdG) was observed in the DNA of colonic mucosa and liver. The 8-OHdG formation reached the maximal level at about 24 h after the DMII injection. On the other hand, no increase of 8-OHdG was observed in the DNA of the kidney. Drinking green tea extract (GTE) for ten days prior to the DMH injection significantly inhibited the formation of 8-OHdG in the colon. These findings demonstrate that DMH causes oxidative damage to the DNA of its target organ, and that GTE protects colonic mucosa from this oxidative damage.

1,2-Dimethylhydrazine↗
PubMed1995

Establishment and characterization of IRTA17 and IRTA21, two novel acute non-lymphocytic leukaemia cell lines with t(16;21) translocation.

The t(16;21)(p11;q22) translocation is an infrequent chromosomal abnormality, but seems specific to acute non-lymphocytic leukaemia (ANLL). We established two cell lines with t(16;21)(p11;q22) from the bone marrow of a patient with ANL in relapse. Their morphological, karyotypic, immunohistochemical and genetic features are examined. Although both cell lines show monocytoid features morphologically, they express only CD13 (My7) and CD34, and neither expressed monocytoid or lymphoid markers. Reverse transcription-polymerase chain reaction showed that both cell lines expressed a similar TLS-ERG chimaeric mRNA as a result of the t(16;21)(p11;q22) translocation. As far as we know, there is no report of a leukaemia cell line with t(16;21). These cell lines represent a useful tool for leukaemia research.

Adult↗
PubMed1995

Design of a centrifugal blood pump with magnetic suspension.

A new concept blood pump, whose impeller is suspended by permanent magnets and a mechanical pivot without seals or ball bearings, is presented in this paper. The primary aim of the blood pump is an application to implantable artificial hearts. The prototype model is of a centrifugal type with a four-vaned semiopen impeller 50 mm in diameter. Since this mechanism has no seals or ball bearings, flow stagnation or heat generation that might cause blood cell denaturation is expected to be small. The results of performance testing for the prototype model 2 were satisfactory regarding pump head and efficiency. The radial-suspension magnets and the magnetic coupling were stable. As a result, the present mechanism has been verified to be a candidate applicable to implantable artificial hearts.

Biomechanical Phenomena↗
PubMed1995

4-Aminopyridine block of the noninactivating cloned K+ channel Kv1.5 expressed in Xenopus oocytes.

The blocking action of 4-aminopyridine (4-AP) on the cloned K+ channel Kv1.5 expressed in Xenopus oocytes was studied using the two-microelectrode voltage-clamp method. Application of 4-AP to the bath solution reversibly suppressed the expressed current in a voltage- and concentration-dependent manner decreasing with membrane depolarization and with a half-maximal inhibitory concentration of 0.14 mM (at +40 mV). Both block and unblock occurred mainly during a depolarization when channels were activated. With successive depolarizations, 4-AP decreased not only the peak amplitudes of the current in successive pulses, but also the current during a depolarization. Upon washout of 4-AP, the current recovered with successive depolarizations, whereas no recovery of the current was noted in the absence of depolarizations. The extent of block markedly increased with alkalization of the external solution and decreased with acidification. External application of 4-amino-pyridine methiodide, a charged form of a quaternary 4-AP derivative, did not affect the current, but internal application markedly suppressed the current, indicating the drug gained access to the channel from the cytoplasmic side. These data suggest that 4-AP crosses the membrane in its uncharged form and acts from inside of the cell in its charged form, resulting in block of the channels with higher affinity to the open state.

4-Aminopyridine↗
PubMed1995

The role of the left atrial appendage. A volume loading study in open-chest dogs.

Although the left atrial appendage has a quite unique structure, its function remains unclear. To clarify the function of the left atrial appendage, changes in its anteroposterior, transverse and longitudinal dimensions, and in the anteroposterior dimension of the left atrial body were measured by a sonomicrometer during volume loading in open chest dogs. In the control state, fractional shortening of the transverse dimension of the appendage was greater than that of the atrial body. After dextran infusion, each dimension of the appendage and body, measured just before atrial contraction, increased curvilinearly. The percent increase in appendage dimensions was greater than that of the atrial body dimension (p < 0.05). Systolic shortenings of the appendage increased until mean left atrial pressure reached approximately 15 mmHg but after further pressure elevation, it decreased. In postmortem isolated hearts, the appendage volume was 17.2 +/- 4.4% of the whole left atrial volume. These findings indicate that the appendage has a considerable volume with a greater compliance and assists left ventricular filling during atrial contraction by a Frank-Starling mechanism.

Animals↗
PubMed1995

Effects of heart rate on left atrial contractile performance and left ventricular filling during atrial systole in dogs.

Left ventricular (LV) diastolic filling and left atrial (LA) contribution have been investigated in patients with heart disease. However, many of these studies were not conducted at a constant heart rate, and the effects of heart rate remain unclear. The purpose of this study was to clarify the effects of the heart rate on left atrial contractile performance and left ventricular filling during atrial systole. The changes in LA and LV dimensions and pulmonary venous (PV) flow were determined in 9 open-chest dogs by a sonomicrometer and an electromagnetic flowmeter. With a stepwise decrease in the pacing rate from 110 beats/minute to 70 beats/minute, the LA dimension just before atrial contraction increased from 21.4 +/- 0.6 mm to 23.1 +/- 0.7 mm (p < 0.01), and the LA systolic shortening increased from 1.6 +/- 0.1 mm to 2.1 +/- 0.1 mm (p < 0.01). However, the calculated LV filling volume during atrial systole decreased from 1.9 +/- 0.3 ml to 1.4 +/- 0.2 ml (p < 0.01). The PV flow during atrial systole was directed toward the LA, and the LA influx volume from PV decreased from 0.6 +/- 0.1 ml to 0.2 +/- 0.04 ml (p < 0.01). With a decrease in the pacing rate, the LA Frank-Starling mechanism operated. However, LV filling during atrial systole decreased because of the decrease in PV flow to the LV via the LA. Thus, LA contractile performance cannot always be evaluated from LV filling.

Animals↗
PubMed1995

Choroid plexus carcinoma in the lateral ventricle--case report.

A 68-year-old male presented with choroid plexus carcinoma in the left lateral ventricle manifesting as dysarthria and gait disturbance. Magnetic resonance imaging showed a homogeneously enhanced mass in the trigone of the left lateral ventricle. Selective left posterior cerebral arteriography showed the tumor was fed by the left medial posterior choroidal artery. Detailed examinations found no evidence of an extraneural primary focus. He underwent partial removal of the tumor followed by local Lineac irradiation (50 Gy). After irradiation, the serum level of carcinoembryonic antigen decreased and the size of the residual tumor was reduced.

Adenocarcinoma↗