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Biomedical subjects

R Yamamoto

Publications and source records attributed to R Yamamoto.

At least 181 records · Page 10Linked to original sources
PubMed1996

Plant growth processes in Arabidopsis under microgravity conditions simulated by a clinostat.

The life cycle of Arabidopsis plants was examined by growing them on a horizontal clinostat. Seeds on agar media were allowed to germinate and seedlings were grown under a simulated microgravity on a horizontal clinostat. Clinorotation (3 rpm) did not appear to interfere with germination of plant seeds and development of cotyledons and leaves. Stress relaxation parameters of the cell wall, the minimum relaxation time and the relaxation rate did not appear to be affected by clinostat rotation. On the other hand, the length of inflorescences was reduced to 61-62% by clinostat rotation. Rotation was found to inhibit the polar transport of auxin, although inflorescence growth and auxin transport were not completely inhibited. From these facts, it is possible that the life cycle in Arabidopsis plants could be accomplished in space, although growth phenomena involving auxin transport and its action may be disturbed. Plants may have a capacity to grow in space and we may be able to cultivate crops in space.

Arabidopsis↗
PubMed1996

[Trial of bladder sparing for patients with invasive bladder cancer by transurethral resection and intra-arterial chemotherapy].

BACKGROUND: We reviewed our experience with bladder conservative treatment for invasive bladder cancer in 20 patients to investigate which type of tumor was suitable for organ conservation. METHODS: We performed radical transurethral resection with dissection to deep layer of the muscle plus intra-arterial chemoinfusion of the cis-platinum at a dose of 80-100 mg/body twice at least, and the recurrent tumor was treated by the same procedure. There were 13 cases of stage T2 and 7 cases of stage T3a. All patients were pathologically diagnosed transitional cell carcinoma with 9 cases of grade 2 and 11 cases of grade 3. RESULTS: With a follow-up of 36 months (range 18 to 82), 15 (75%) of 20 patients were survived and 10 (50%) of 20 patients were free of tumor. Of 5 patients with residual or recurrent tumor, 2 patient underwent cystectomy and the others were required transurethral resection. Of 5 patients died, 4 patients died of cancer all with distant metastasis (lung meta: 2 cases, liver meta: 2 cases). In reference to tumor characteristics, all 4 patients had over 3 cm diameter tumors with non-papillary surface and 3 of 4 patients had invasive tumors extended to bladder neck and prostatic urethra. Of 15 patients alive, 7 (47%) patients had non-papillary tumors, 9 (60%) had grade 3 tumors, 5 (33%) had T3a tumors, but invasion of the prostate urethra was recognized in only 3 patients (20%). CONCLUSION: We had possibility of doing organ prevention therapy for the patients with invasive bladder cancer, even though it was non-papillary or grade 3 tumor. On the other hand, it was thought that a conservative approach should not be considered in patients with large non-papillary tumors that extended to bladder neck and prostatic urethra.

Adult↗
PubMed1996

Nitric oxide-sensitive and -insensitive contractions of the isolated rabbit iris sphincter muscle.

PURPOSE: The rabbit iris sphincter muscle is innervated by cholinergic and tachykinergic nerves that regulate its tone. To clarify the involvement of nitric oxide (NO) in the postsynaptic regulation of the rabbit iris sphincter muscle tone, the authors examined the effects of NO-related agents on the cholinergic contraction induced by carbamylcholine (carbachol) and the tachykinergic contraction induced by neurokinin A. METHODS: The motor activity of the ring-shaped rabbit iris sphincter muscle was measured isometrically. Sodium nitroprusside (SNP, a NO donor) was administered between the first and second administrations of carbachol and neurokinin A, each of which induced sustained contraction. The effects of carboxy-2-phenyl-4,4,5,5,-tetramethyl-imidazoline-l-oxyl-3-oxide (carboxy-PTIO, a scavenger of NO radicals), NG-monomethyl-L-arginine (L-NAME, an inhibitor of NO formation from L-arginine), and methylene blue (an inhibitor of soluble guanylate cyclase) on contractions induced by carbachol and neurokinin A also were studied. Cyclic guanosine monophosphate (GMP) content in the muscle was determined by radioimmunoassay. RESULTS: Sodium nitroprusside inhibited carbachol-induced contractions of the iris sphincter muscle in a concentration-dependent manner but had no effect on neurokinin A-induced muscle contractions. Carboxy-PTIO and methylene blue significantly diminished the inhibitory effect of SNP on carbachol-induced contractions. L-NAME had no effect on contractions induced by either carbachol or neurokinin A. Sodium nitroprusside alone increased cyclic GMP accumulation in a concentration-dependent manner. CONCLUSIONS: This study showed that SNP inhibited cholinergic contractions mainly through a cyclic GMP-dependent mechanism but did not affect the tachykinergic contractions, indicating that cholinergic contraction is NO sensitive, whereas tachykinergic contraction is NO insensitive. These findings suggest that in rabbits, the cholinergic and tachykinergic responses have distinct features for the fine adjustment of the iris sphincter muscle tone.

Animals↗
PubMed1996

[Case of benign metastaxsizing leiomyoma of the lungs].

A 51-year-old woman with bilateral multiple pulmonary metastases of uterine leiomyoma was reported. The patient had undergone a hysterectomy for uterine myoma in 1976. In 1981, routine chest roentgenograms showed three nodular lesions in the right lung with well-defined margins. The patient received no treatment because she was asymptomatic. In January 1993, she consulted a gynecologist because of acute lower abdominal pain and an abdominal mass, and bilateral pulmonary tumors were found. The retroperitoneal solid tumor was extirpated in the first operation, and histological findings showed that it was a benign leiomyoma. The pulmonary tumors, extirpated in the second operation, were benign leiomyoma, also. The clinical course and histological findings suggested that this was a case of benign metastasizing leiomyoma. This disease is rare, 21 case have been reported in Japan.

Female↗
PubMed1996

[Successful repair of right atrial rupture due to nonpenetrating trauma of the chest].

A 24-year-old male was brought to our hospital after being injured in a traffic accident. On arrival, his blood pressure was 70/44 mmHg and his pulse rate was 135/min and regular. Chest X-p revealed cardiomegaly but there was no pleural effusion or bone fracture. Echocardiogram revealed cardiac tamponade and he was diagnosed as cardiac rupture due to non penetrating trauma. Under midline sternotomy, right atrial rupture was repaired. The patient developed cardiac arrest lasting approximately 8 minutes during anesthetic induction, so he needed to be ventilated for 8 days. However his postoperative course was not so eventful and he was discharged 38 days after surgery without any neurophysiological disturbance.

Accidents, Traffic↗
PubMed1996

[An analysis of pelvic and para-aortic lymph node metastasis in ovarian carcinoma by systematic retroperitoneal lymph node dissection].

We performed a systematic retroperitoneal lymph node dissection (RPLND) on 137 patients with primary ovarian carcinoma, of whom 97 had undergone RPLND during the primary surgery before chemotherapy and 40 had undergone RPLND during the secondary cytoreductive surgery after preoperative chemotherapy. The tentative staging of the ovarian carcinoma used in this study was determined according to the FIGO criteria without considering the pathologic findings of retroperitoneal lymph nodes. Nodal metastasis was seen in 21.9% (30/137) of them. Thirteen had positive pelvic lymph nodes (PLN) but no positive para-aortic nodes (PAN). Eleven had both positive PLN and positive PAN. Six had positive PAN but no positive PLN. The PAN was the most frequent site of metastasis (17/137). Next were the common iliac, obturator, and lateral group of deep inguinal nodes. Solitary metastasis in the patients who had undergone RPLND during the primary surgery was seen in a PAN and a common iliac node. Among 24 patients with PLN metastasis, there was a significant (p < 0.05) difference in the number of positive PLN between the patients with PAN metastasis (5.27 +/- 3.00) and the patients without PAN metastasis (2.62 +/- 1.66). These results indicate that the PAN and common iliac nodes are the most important site of nodal metastasis in ovarian carcinoma. The metastasis to PLN such as obturator node and internal iliac node seems to occur independently of the PAN metastasis, and the PAN metastasis occurs not only through the direct route but also as a consequence of extension of PLN metastases. Systematic retroperitoneal lymph node exploration therefore seems to be necessary to clarify the lymph node status.

Aorta↗
PubMed1996

[Prognostic factors of resected pulmonary metastases of osteogenic sarcoma].

From December 1979 to December 1994, 22 patients with osteogenic sarcoma underwent a total of 34 thoracotomies for resection of pulmonary metastases in our department. We did a retrospective study to identify prognostic factors. The tumor doubling time (TDT) calculated for 21 patients before the first (if multiple) resection was not correlated with days of survival after resection of the primary tumor, nor was it correlated with days of survival after the first (if multiple) resection of the pulmonary metastatic tumors. Of the nine patients who underwent at least two thoracotomies, the TDT calculated from X-ray films taken before the second (or later) thoracotomy was significantly shorter than the TDT calculated before the preceding thoracotomy (p < 0.05). The disease-free interval (DFI) after resection of the primary tumor was correlated with the days of survival after that resection (p < 0.001) and also with survival after resection of the pulmonary metastatic tumors (p < 0.01). This DFI of patients who survived at least 2 years from the date of the resection of the primary tumor was significantly longer than in patients who survived less than 2 years from that date (p < 0.05). The most significant prognostic factor was this DFI. The cumulative survival rate was 42.4% at three years and 33.9% at five years, with an operative mortality of 0%.

Adolescent↗
PubMed1996

Pseudoaneurysm of the left ventricle following repair for ventricular septal perforation.

The patient was a 64-year-old man who was treated surgically for an infarct-related ventricular septal perforation. Pseudoaneurysm of the left ventricle was recognized on the 38th postoperative day. Emergency surgery was performed. It seemed that insufficient resection of the infarcted myocardium was performed during the initial surgery to avoid narrowing the ventricular dimension by direct closure of the left ventricle, but this resulted in pseudoaneurysm of the left ventricle. Left ventricular free wall plasty with a patch should be performed during the initial surgery.

Aneurysm, False↗
PubMed1995

Attenuation of vasoactive intestinal peptide enhancement of colon carcinogenesis by ornithine decarboxylase inhibitor.

The effects of combined administration of vasoactive intestinal peptide (VIP) and the ornithine decarboxylase (ODC) inhibitor, 1,3-diaminopropane (DAP), on development of colon tumors induced by azoxymethane (AOM), on ODC activity of the colon wall, and on the labelling index of colon epithelial cells were investigated in inbred Wistar rats. Rats received weekly subcutaneous injections of AOM for 10 weeks and subcutaneous injections of VIP every other day and drinking water containing DAP (2.5 milligrams) ad libitum until the end of the experiment at week 45. Administration of VIP significantly increased the incidence of colon tumors at week 45. It also resulted in significant increases in colon ODC activity and in the labelling index during administration of AOM, but not after its cessation. Administration of both DAP and VIP significantly reduced the enhanced colon carcinogenesis by VIP. The DAP significantly attenuated the VIP enhancement of colon ODC activity and of the labelling index during AOM administration. These findings indicate that ODC inhibition attenuated enhancement of colon carcinogenesis, and suggest that enhancement of colon carcinogenesis by VIP may be mediated through its polyamine biosynthesis.

Adenocarcinoma↗
PubMed1995

Apoptosis of cultured mouse luteal cells induced by tumor necrosis factor-alpha and interferon-gamma.

BACKGROUND: Macrophages and T lymphocytes have been identified in the regressing corpus luteum, and they are thought to participate in structural luteolysis (destruction and removal of luteal cells). Since these cells produce cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), we investigated the effects of these two cytokines on death of luteal cells in vitro. METHODS: Mouse luteal cells were cultured in serum-free medium with TNF-alpha at 0, 500, 1,000, 3,000, or 5,000 U/ml in the presence or absence of IFN-gamma at 1,000 U/ml for 3 or 6 days. Then, for estimation of the actions of these cytokines on induction of luteal cell death, we determined the number of viable cells, the percentage of fragmented DNA in total DNA extracted from cultured cells, and the percentage of cells with fragmented DNA in their nuclei by the trypan blue exclusion test, the sensitive micromethod for DNA assay, and the in situ DNA 3' end labeling method, respectively. DNA fragmentation was also analysed by agarose gel electrophoresis, and cultured cells were examined by electron microscopy. RESULTS: On day 3 of culture, IFN-gamma alone at 1,000 U/ml or TNF-alpha alone at 500-5,000 U/ml did not decrease the number of viable cells, but a combination of IFN-gamma (1,000 U/ml) and TNF-alpha (5,000 U/ml) did. On day 6, IFN-gamma alone at 1,000 U/ml or TNF-alpha alone at 500, 1,000 and 3,000 U/ml did not decrease the number of viable cells, whereas TNF-alpha alone at 5,000 U/ml did, and combinations of IFN-gamma and TNF-alpha at 1,000, 3,000, and 5,000 U/ml decreased the number of viable cells in proportion to the concentration of TNF-alpha. On days 3-6 of culture, combinations of IFN-gamma and TNF-alpha that decreased the number of viable cells also increased the percentages of fragmented DNA in total DNA of cultured luteal cells and the percentages of luteal cells with fragmented DNA in their nuclei. Agarose gel electrophoresis of fragmented DNA showed a ladder-like pattern, and electron microscopic examination showed luteal cells with the characteristics of apoptosis. CONCLUSIONS: The presence of IFN-gamma modulates the ability of TNF-alpha to induce a reduction in the number of viable cells, although TNF-alpha alone at high concentrations can induce a reduction in the number of viable cells.

Animals↗
PubMed1995

Cloning and properties of a rice gene encoding phenylalanine ammonia-lyase.

Phenylalanine ammonia-lyase (PAL) genomic sequences were isolated from a rice (Oryza sativa L.) genomic library using a PCR-amplified rice PAL DNA fragment as a probe. There is a small family of PAL genes in the rice genome. The nucleotide sequence of one PAL gene, ZB8, was determined. The ZB8 gene is 4660 bp in length and consists of two exons and one intron. It encodes a polypeptide of 710 amino acids. The transcription start site was 137 bp upstream from the translation initiation site. Rice PAL transcripts accumulated to a high level in stems, with lower levels in roots and leaves. Wounding of leaf tissues induced ZB8 PAL transcripts to a high level. In rice suspension-cultured cells treated with fungal cell wall elicitors, the ZB8 PAL transcript increased within 30 min and reached maximum levels in 1-2 h. The transcription of the ZB8 gene was investigated by fusing its promoter to the reporter gene beta-glucuronidase (GUS) and transforming the construct into rice and tobacco plants, as well as rice suspension-cultured cells. High levels of GUS activity were observed in stems, moderate levels in roots and low levels in leaves of transgenic rice and tobacco plants. Histochemical analysis indicated that in transgenic rice the promoter was active in root apical tips, lateral root initiation sites, and vascular and epidermal tissues of stems and roots. In rice flowers, high GUS activity was observed in floral shoots, receptacles, anthers and filaments, occasionally GUS activity was also detected in lemma and awn tissues. In tobacco flowers, high GUS activity was detected in the pink part of petals. Consistent with the activity of endogenous PAL transcripts, wounding of rice and tobacco leaf tissues induced GUS activity from low basal levels. Tobacco mosaic virus (TMV) infection of tobacco leaves induced GUS activity to a high level. Fungal cell wall elicitors strongly induced GUS activity and GUS transcripts to high levels in transgenic rice suspension-cultured cells. We demonstrated that the promoter of ZB8 gene is both developmentally regulated and stress-inducible.

Amino Acid Sequence↗
PubMed1995

Large- and small-conductance Ca(2+)-activated K+ channels: their role in the nicotinic receptor-mediated catecholamine secretion in bovine adrenal medulla.

In cultured bovine adrenal chromaffin cells, charybdotoxin and iberiotoxin (inhibitors of the large-conductance Ca(2+)-activated K+ channel) as well as apamin (an inhibitor of the small-conductance Ca(2+)-activated K+ channel), at 1-100 nM, suppressed carbachol-induced 86RB+ efflux, augmented carbachol-induced 45Ca2+ influx via voltage-dependent Ca2+ channels and catecholamine secretion and had no effect on carbachol-induced 22Na+ influx via nicotinic receptors, a prerequisite for Ca2+ channel activation by carbachol. 45Ca2+ influx caused by high K+ (a direct activation of voltage-dependent Ca2+ channels) was also enhanced by these K+ channel inhibitors, with the concentration-response curves being similar to those for carbachol-induced 45Ca2+ influx. Dendrotoxin and mast cell degranulating peptide (inhibitors of voltage-dependent K+ channels), on the other hand, did not alter carbachol-induced 86Rb+ efflux or 45Ca2+ influx. These results suggest that the stimulation of nicotinic receptors eventually opens large- and small-conductance Ca(2+)-activated K+ channels, and that the blockade of these Ca(2+)-activated K+ channels results in gating of voltage-dependent Ca2+ channels and thereby augments catecholamine secretion from bovine adrenal chromaffin cells.

Adrenal Medulla↗
PubMed1995

Gravitropic response in Eichhornia cressipes (Water Hyacinth) 1. Process of gravitropic bending in the peduncle.

In the last half of the anthokinetic cycle in Eichhornia cressipes the peduncle showed a two-step bending response which started after the completion of the flowering: the primary bending in the upper region and the second one in the base of the peduncle. In the present study, only the primary bending response was examined and the following results were obtained. (1) Under the condition in the Western Japan, the anthokinetic cycle completed in 36-40 hr. The inflorescence started to grow during night, reaching the full flowering stage next morning, and the bending was initiated in the evening and completed next morning. (2) The bending was a positive gravitropism since the peduncle did not show bending when it was placed on a horizontal clinostat rotating at 2-3 rpm, or when the plant was placed up-side-down. (3) Before the end of flowering phase, the peduncle showed a normal negative gravitropic response but afterward it acquired the property to show a positive gravitropic response. (4) The bending was due to the extension of convex side of the peduncle, accompanied by a shrinkage of the concave side. The extension of the upper side was caused by cell extension. At the turning point from negative to positive gravitropic response, the extension of the peduncle ceased for several hours. From the above results it is concluded that the primary bending response of the peduncle in water hyacinth was a positive gravitropism.

Biomechanical Phenomena↗
PubMed1995

Clinical significance of reverse redistribution phenomenon after coronary artery bypass grafting.

The reverse redistribution (RR) phenomenon is a decrease in thallium 201 uptake during redistribution compared with 201Tl uptake immediately after exercise. We evaluated RR in 23 patients after coronary artery bypass grafting. Postoperative RR was present in 48% and was significantly more common in patients with a history of myocardial infarction (62%). The patients were classified according to the presence (+) or absence (-) of RR. An analysis of left ventricular wall motion showed significant improvement after coronary artery bypass grafting in the RR+ group (n = 12) but not in the RR- group (n = 11). Quantitative myocardial viability was evaluated using the defect volume ratio, mean defect severity, and defect severity index. The preoperative defect volume ratio was higher in the RR+ group than in the RR- group (p < 0.05). In the RR- group, no improvement in these indices was observed after operation. In contrast, the RR+ group showed significant improvement in all three indices (p < 0.05). These results indicate that after coronary artery bypass grafting, an adequate blood supply to the remaining myocardium may induce RR. This phenomenon, therefore, may be a significant indicator of postoperative myocardial viability.

Adult↗
PubMed1995

DNA diversity among isolates of Campylobacter jejuni detected by PCR-based RAPD fingerprinting.

A PCR-based randomly amplified polymorphic DNA method was used to amplify Campylobacter jejuni DNA using a single oligonucleotide primer derived from either a homologous source or from Mycoplasma gallisepticum. The method was able to detect the heterogeneity of amplified DNA from human, chicken and turkey sources and can be used as a tool to study the epidemiology of Campylobacter jejuni infection.

Animals↗