Biomedical subjects

A Yamanaka

Publications and source records attributed to A Yamanaka.

At least 19 recordsLinked to original sources

PubMed2004

Improved conception in timed-artificial insemination using a progesterone-releasing intravaginal device and Ovsynch protocol in postpartum suckled Japanese Black beef cows.

The primary objective was to determine the effect of supplemental progesterone, administered via an intravaginal device (CIDR), on conception rates to timed-artificial insemination (timed-AI) in postpartum suckled Japanese Black beef cows treated with the Ovsynch protocol. A secondary objective was to compare the effects of treatments on plasma concentrations of progesterone and estradiol. Cows in the control group (Ovsynch, n=38) received a standard Ovsynch protocol (100 microg GnRH analogue on Day 0, 500 microg PGF2alpha analogue on Day 7, and 100 microg GnRH analogue on Day 9), with AI on Day 10, approximately 20 h after the second GnRH treatment. Cows in the treatment group (Ovsynch+CIDR; n=40) received a standard Ovsynch protocol plus a CIDR for 7 days (starting on Day 0). Plasma progesterone concentrations were determined on Days 0, 1, 7, 9, 10, and 17 and plasma estradiol-17beta concentrations were determined on Days 7, 9, 10, and 17. The odds ratio for likelihood of conception was 3.29 times greater (P=0.02) in the Ovsynch+CIDR group compared to Ovsynch group. The conception rate was greater (P=0.03) in the Ovsynch+CIDR group than in the Ovsynch group (72.5% versus 47.7%). Insertion of a CIDR device significantly increased plasma progesterone concentrations only on Days 1 and 7 (P<0.001 and P=0.05, respectively), but had no significant effect on plasma estradiol-17beta concentrations. Including a CIDR with the Ovsynch protocol significantly improved conception rates in postpartum suckled Japanese Black beef cows.

Administration, Intravaginal↗

PubMed2003

c-Axis Raman scattering spectra of MgB2: observation of a dirty-limit gap in the pi bands.

Raman scattering spectra from the ac face of thick MgB2 single crystals were measured in zz, xz, and xx polarizations. In zz and xz polarizations a threshold at around 29 cm(-1) forms in the below T(c) continuum but no pair-breaking peak is seen, in contrast to the sharp pair-breaking peak at around 100 cm(-1) in xx polarization. The zz and xz spectra are consistent with Raman scattering from a dirty superconductor while the sharp peak in the xx spectra argues for a clean system. Analysis of the spectra resolves this contradiction, placing the larger and smaller gap magnitudes in the sigma and pi bands and indicating that relatively strong impurity scattering is restricted to the pi bands.

Journal Article↗

PubMed2002

Orexin-mediated feeding behavior involves both leptin-sensitive and -insensitive pathways.

Orexin-A and -B are neuropeptides that are implicated in the regulation of vigilance states and energy homeostasis. Orexins are specifically produced by neurons located within the lateral hypothalamic area (LHA), a region implicated in the regulation of feeding behavior. Here, we examined the functional interactions between orexins and anorectic factors [leptin, alpha-melanocyte-stimulating hormone (alpha-MSH) and glucagon-like peptide-1 (GLP-1)] in rats. Intracerebroventricular injection of orexin-A (10 nmol) potently augmented food intake in rats. Neuropeptide Y (NPY) (0.3 nmol) and galanin (3 nmol) also induced a transient increase in food intake. Both NPY- and galanin-induced feeding behaviors were completely inhibited by preadministration of leptin (3 microg), while the same or a higher dose (10 microg) of leptin only partially inhibited orexin-A or -B-induced increase of food intake. Preadministration of anorectic peptides (alpha-MSH and GLP-1), which are shown to be regulated by leptin, abolished NPY-induced feeding; however, orexin-induced feeding was only partially inhibited by these anorectic peptides. These observations suggest that NPY- and galanin-induced increases of feeding involve a leptin-sensitive pathway, while orexin-induced feeding involves both leptin-sensitive and -insensitive pathways.

Animals↗

PubMed2001

Two-photon resonant third-harmonic generation in La2CuO4.

Combining linear absorption and nonlinear third harmonic generation (THG) experiments, we investigate details of the electronic structure of the highly correlated electronic system in La2CuO4. We demonstrate strong THG mainly due to the charge transfer excitation from O (2p(sigma)) to Cu (3d(x2-y2)). The THG spectrum shows pronounced features due to three-photon and two-photon resonance enhancement as well as quantum interference effects. We obtain excellent agreement with a THG spectrum calculated in terms of the excitonic cluster model and can identify both odd and even symmetry excitation modes.

Journal Article↗

PubMed2001

Mice lacking the M3 muscarinic acetylcholine receptor are hypophagic and lean.

Members of the muscarinic acetylcholine receptor family (M1-M5) have central roles in the regulation of many fundamental physiological functions. Identifying the specific receptor subtype(s) that mediate the diverse muscarinic actions of acetylcholine is of considerable therapeutic interest, but has proved difficult primarily because of a lack of subtype-selective ligands. Here we show that mice deficient in the M3 muscarinic receptor (M3R-/- mice) display a significant decrease in food intake, reduced body weight and peripheral fat deposits, and very low levels of serum leptin and insulin. Paradoxically, hypothalamic messenger RNA levels of melanin-concentrating hormone (MCH), which are normally upregulated in fasted animals leading to an increase in food intake, are significantly reduced in M3R-/- mice. Intra-cerebroventricular injection studies show that an agouti-related peptide analogue lacked orexigenic (appetite-stimulating) activity in M3R-/- mice. However, M3R-/- mice remained responsive to the orexigenic effects of MCH. Our data indicate that there may be a cholinergic pathway that involves M3-receptor-mediated facilitation of food intake at a site downstream of the hypothalamic leptin/melanocortin system and upstream of the MCH system.

Animals↗

PubMed2001

Multiple thymoma with myotonic dystrophy.

A case of multiple thymoma associated with myotonic dystrophy is reported. The patient was a 42-year-old man who had two separate encapsulated thymoma in the anterior mediastinum, at 3 cm in diameter on the right side, and at 4 cm in diameter on the left. Extended thymo-thymomectomy was performed. Microscopically, the tumor in the right thymic lobe was predominantly mixed type, and that in the left predominantly epithelial type. Neuromuscular disease appeared to develop, with severe sputum retention in the larynx and he was referred to neurology at 6 months after surgery. On examination, he presented a characteristic hatchet face, muscle atrophy, muscle weakness, percussion myotonia and grip myotonia, and diagnosis was revised to be multiple thymoma associated with myotonic dystrophy. This association is extremely rare. It is difficult to clarify whether this association was a syndrome or coincidence.

Adult↗

PubMed2001

Alteration of the ocular surface with recurrence of granular/avellino corneal dystrophy after phototherapeutic keratectomy: report of five cases and literature review.

PURPOSE: To study the changes in ocular surface findings with recurrence after phototherapeutic keratectomy (PTK) in patients with Avellino and granular dystrophy. DESIGN: Observational case series. PARTICIPANTS: Five eyes of five patients with recurrent granular/Avellino corneal dystrophy after PTK seen at Kobe Kaisei Hospital were studied. INTERVENTION: The patients underwent routine ophthalmic examinations, corneal sensitivity measurements, tear film breakup time (BUT), Schirmer test, tear film lipid layer interferometry, and conjunctival impression cytology. MAIN OUTCOME MEASURES: The alterations of clinical features, tear function, and conjunctival impression cytology parameters with a recurrence after PTK were investigated. RESULTS: The average pre-PTK corneal sensitivity and tear film breakup time were low in all five patients. Tear film lipid layer interferometry grade and conjunctival squamous metaplasia displayed higher grades before PTK. All of these parameters improved gradually after PTK and were maintained until a recurrence, which was associated with further worsening of the corneal sensitivity, tear function, and impression cytology parameters. CONCLUSIONS: Although PTK improves the ocular surface health in granular/Avellino corneal dystrophies, recurrence of the initial dystrophy is associated with decline of the ocular surface health parameters. Our findings also suggest that corneal epithelium is most probably involved in the recurrence of the disease process in Avellino/granular corneal dystrophy.

Aged↗

PubMed2001

Refractive changes after excimer laser phototherapeutic keratectomy.

PURPOSE: To study the visual and refractive changes in patients with superficial corneal opacities after excimer laser phototherapeutic keratectomy (PTK). SETTING: Eye Clinic, Kobe Kaisei Hospital, Kobe, Japan. METHODS: One hundred twelve eyes of 80 patients with superficial corneal opacities had PTK with the Nidek EC-5000 excimer laser system. All patients had routine ophthalmic examinations including uncorrected and Landolt best corrected visual acuity (BCVA) measurements, subjective and objective refractions, keratometry, EyeSys (Premier Laser Systems, Inc.) corneal topography performed before and 1 week and 1, 3, 6, and 12 months after PTK, and pachymetry performed before and 12 months after PTK. The change in refractive status within 12 months of PTK and the relationship between factors such as ablation depth, transition zone (TZ) setting, and use of masking agents and the amount of hyperopic shift were also assessed. RESULTS: The BCVA increased by more than 2 lines in 65.1% of eyes and by 1 line in 24.1%. The BCVA did not change in 12 eyes (10.8%) because of cataract or underlying retinal disease. A mean hyperopic shift of 3.42 +/- 1.15 diopters (D) (range 1.00 to 5.25 D) was seen in all eyes at 12 months. The hyperopic shift peaked 1 month after PTK and tended to decline after that; it stabilized at 12 months. CONCLUSION: Although PTK is a safe and efficient method for the treatment of superficial corneal opacities, induced hyperopia after the procedure remains a major problem. A shallow ablation depth (less than 100 microm), presence of a TZ setting, and use of a masking agent decrease the hyperopic shift significantly.

Adult↗

PubMed2001

Involvement of different activator Ca(2+) in the rate-dependent stretch-induced contractions of canine basilar artery.

Stretch evoked a contraction in a rate-dependent manner in canine basilar artery; slow stretch at rates less than 3 mm/s produced no active tension, whereas quick stretch at rates over 5 mm/s did. Large conductance Ca(2+)-activated K(+) channel blockers, including charybdotoxin, iberiotoxin, and tetraethylammonium (TEA) sensitized the basilar artery to mechanical stimulation. TEA shifted the stretch rate-tension relationship toward the left. Thus, in the presence of TEA, the slow stretch (0.1-3 mm/s) could increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) and active tension. The contraction in response to slow stretch (1 mm/s) was abolished by nicardipine and Gd(3+). Quick stretch (100 mm/s) increased [Ca(2+)](i) and active tension, both of which were partially inhibited by nicardipine or Gd(3+). The Gd(3+)-insensitive component of quick stretch-induced contraction was eliminated by thapsigargin, but not by nicardipine. Ryanodine, cyclopiazonic acid, thapsigargin, U-73122, and calphostin C also abolished the nicardipine-insensitive component of quick stretch-induced contraction. These results suggest that the slow stretch-induced contraction was exclusively dependent on the Ca(2+) influx through L-type voltage-dependent Ca(2+) channels (VDCs), whereas the quick stretch-induced contraction was dependent on Ca(2+) release from sarcoplasmic reticulum (SR) and Ca(2+) influx through L-type VDCs.

Animals↗

PubMed2000

A putative binding protein for lipophilic substances related to butterfly oviposition.

A unique protein of 23 kDa (Jf23) was found in the tarsus of the female swallowtail butterfly, Atrophaneura alcinous. Jf23 has 38% identity with a bilin-binding protein, which was found in the cabbage butterfly, Pieris brassicae, and which has two consensus sequences in common with the members of the lipocalin family, suggesting that it is a binding protein for lipophilic ligands. Western blot analysis showed that Jf23 was expressed only in the female, and not in the male. Electrophysiological response of the female tarsi was stimulated by methanolic extract of their host plant, Dutchman's pipe (Aristolochia debilis). The stimulated response was depressed by the presence of Jf23 antiserum. These results suggest that Jf23 is one of the chemosensory signaling proteins, which plays one or more roles in female butterfly oviposition.

Amino Acid Sequence↗

PubMed2000

Orexins suppress catecholamine synthesis and secretion in cultured PC12 cells.

New orexigenic peptides called orexin-A and -B have recently been described in neurons of the lateral hypothalamus and perifornical area. No orexins have been found in adipose tissues or visceral organs, including the adrenal gland. However, expression of the orexin-receptor 2 (OX2R) in the rat adrenal gland has been reported. To test the effects of orexins on peripheral organs, we investigated their effects on catecholamine synthesis and secretion in the rat pheochromocytoma cell line PC12. Orexin-A and -B (100 nM) significantly reduced basal and PACAP-induced tyrosine hydroxylase (TH) (the rate-limiting enzyme in the biosynthesis of catecholamines) mRNA levels. Orexin-A and -B (100 nM) also significantly inhibited the PACAP-induced increase in the cAMP level, suggesting that the suppressive effect on TH mRNA is mediated, at least in part, by the cAMP/protein kinase A pathway. Furthermore, orexin-A and -B (100 nM) significantly suppressed basal and PACAP-induced dopamine secretion from PC12 cells. Next, we examined whether orexin receptors (OX1R, OX2R) were present in the rat adrenal gland and PC12 cells. In the adrenal glands, OX2R was as strongly expressed as in the hypothalamus, but OX1R was not detected. On the other hand, neither OX1R nor OX2R was expressed in PC12 cells. However, binding assays showed equal binding of orexin-A and -B to PC12 cells, suggesting the existence in these cells of some receptors for orexins. These results indicate that orexins suppress catecholamine release and synthesis, and that the inhibitory effect is mediated by the cAMP/protein kinase A pathway.

Adrenal Gland Neoplasms↗

PubMed2000

Hyper-raman scattering observation of the boson peak in vitreous silica

Hyper-Raman spectroscopy is used to investigate low frequency vibrations of various silica glasses. A strong boson peak is observed. The corresponding modes are inactive in infrared and Raman spectra, and are nonacoustic in nature. The shape of this boson peak essentially matches the total density of vibrational states (DOS), with a constant coupling coefficient C. This and other indications suggest that these modes actually dominate the DOS of silica.

Journal Article↗

PubMed2000

Neuroendocrine regulation of seasonal morph development in a bivoltine race (Daizo) of the silkmoth, Bombyx mori L.

We investigated the neuroendocrine regulation of the development of seasonal morphs in a bivoltine race (Daizo) of the silkmoth, Bombyx mori, by decerebration, the transplantation of brain-suboesophageal ganglion (Br-SG) complexes and the injection of active neuropeptides. When brains were removed from fresh pupae destined to develop into summer morphs (SD pupae) by embryonic and larval exposures to short days at low temperature, the pupae developed into autumn or intermediate morphs. However, in pupae destined to develop into autumn morphs (LD pupae), the operation did not show an effect on seasonal morph development. Br-SG complexes were excised from fifth-instar LD and fifth-instar SD larvae 2 days after larval ecdysis and were transplanted into the abdomen of SD larvae of the same age. The Br-SG complexes of LD larvae, but not the Br-SG complexes of SD larvae, shifted the host's seasonal morph development toward the autumn morph. Furthermore, when treated with crude pupal SGs extract and diapause hormone (DH), fresh SD pupae developed into autumn or intermediate morphs, respectively. Possibly the development of seasonal morphs in the silkmoth, B. mori, is regulated by a novel function of DH. Alternatively, DH may act on the imaginal wing disks at an earlier stage than on the ovaries.

Journal Article↗

PubMed2000

Orexin-induced food intake involves neuropeptide Y pathway.

Orexins (orexin-A and -B) are recently identified neuropeptides, which are thought to be implicated in the regulation of feeding behavior. We used a NPY-Y1 receptor specific antagonist, BIBO3304, to examine whether NPY is involved in orexin-induced feeding behavior. Intracerebroventricular administration of orexin-A (10 nmol) induced food intake in rats (food intake for 3 h; vehicle 0.3+/-0.2 g vs. orexin-A 10 nmol, 4.0+/-0.5 g, n=4). Orexin-induced feeding behavior was partially inhibited by prior administration of BIBO3304 (3 h food intake: orexin-A 10 nmol, 4.0+/-0.5 g vs. BIBO3304 (60 microgram) + orexin-A 10 nmol, 2.2+/-0.2 g, n=4). A low dose of BIBO3304 (30 microgram) did not show a significant inhibitory effect. BIBO3457, an inactive enantiomer, used as a negative control, did not show any inhibitory effect on orexin-A-induced feeding behavior. Fos expression was observed in NPY-containing neurons in the arcuate nucleus 1 h after orexin-A (10 nmol) was administered intracerebroventricularly (control 0.3+/-0.08%, orexin-A 10.2+/-0.8%, n=5 rats/group). These observations suggest that NPY is involved in orexin-induced feeding behavior. However, BIBO3304 did not completely abolish the effect of orexin-A. These results suggest that orexin-A elicits feeding behavior partially via the NPY pathway. The NPY system could be the one of downstream pathways by which orexin-A induces feeding behavior. Another pathway may also be involved in orexin-A-induced feeding behavior, because BIBO3304 did not completely abolish orexin-A-induced feeding behavior.

Animals↗

PubMed2000

Subtype-specific trafficking of endothelin receptors.

We investigated the subcellular localization of two endothelin receptors (ET(A)R and ET(B)R). To visualize these receptors directly, the C terminus of each receptor was fused to the N terminus of enhanced green fluorescent protein (designated as ETR-EGFP). When transiently expressed in various mammalian cell lines, ET(A)R-EGFP was predominantly localized on the plasma membrane. By contrast, ET(B)R-EGFP was, independent of ligand stimulation, predominantly localized on the intracellular vesicular structures containing Lamp-1. Immunoblot analyses revealed that at steady state ET(B)R-EGFP was highly degraded, and its degradation was inhibited by bafilomycin A(1). Antibody uptake experiments suggested that the ET(B)R-EGFP molecules were internalized from the plasma membrane. It is therefore likely that ET(B)R is first transported to the plasma membrane and then internalized, irrespective of ligand stimulation, to lysosomes where it undergoes proteolytic degradation. Exchanging the C-terminal cytoplasmic tails of the two ETRs revealed that the cytoplasmic tail is responsible for both the intracellular localization and the degradation of the receptors. Deletion of the extreme C-terminal 35 amino acids from both receptors allowed the receptor proteins to localize predominantly in the intracellular vesicles and to degrade. These observations indicate that the cytoplasmic tail of ET(A)R determines its plasma membrane localization. Stimulation with endothelin-1 increased the amount of intact ETR-EGFP fusion proteins without increasing their de novo synthesis, suggesting that binding of endothelin-1 stabilizes the ETRs.

Amino Acid Sequence↗

PubMed2000

Multifocal micronodular pneumocyte hyperplasia in a postmenopausal woman with tuberous sclerosis.

We report a peculiar case of multifocal micronodular pneumocyte hyperplasia (MMPH) without association of pulmonary lymphangioleiomyomatosis (LAM) in a 56-year-old postmenopausal woman with tuberous sclerosis. This case is surmised to be a forme fruste of tuberous sclerosis. Computed tomography demonstrated multiple micronodules, measuring up to 5 mm in size, present in the bilateral lung fields, but no cystic changes. A proliferation of pleomorphic type-II pneumocytes lining the thickened alveolar septa in an adenomatoid pattern, with an associated increase in alveolar macrophages, was observed without typical nuclear atypia. In fully developed lesions, the ingrowth of more proliferating type-II pneumocytes into the thickened alveolar septa and macrophages filling the alveolar lumens were characteristic findings. Proliferation of immature smooth muscle cells suggesting LAM was not observed. Positive immunohistochemical stains for cytokeratin, epithelial membrane antigen, and surfactant apoproteins A and B, and negative staining for HMB45, alpha-1 smooth muscle actin, desmin, and carcinoembryonic antigen confirmed the characteristics of alveolar lining cells in each MMPH lesion. MMPH associated with tuberous sclerosis in the postmenopausal woman appears to be similar to that described in premenopausal women. The present case is familial rather than sporadic and suggests no relationship between the development of MMPH and the underlying hormonal state.

Female↗

PubMed2000

Analyses of segmental lymph node metastases and intrapulmonary metastases of small lung cancer.

BACKGROUND: Curativity and indications for limited resection of small peripheral lung cancer remain controversial. METHODS: Pathologic investigations of segmental lymph node metastases and intrapulmonary metastases in the resected lobe were performed for 94 small peripheral lung cancers (3.0 cm or less in diameter). RESULTS: Nine patients had segmental lymph node metastases, 1 had intrapulmonary metastases, and 1 had both. Of these 11 patients, 5 had metastases limited to the primary tumor-bearing segments, 2 had metastases in nonprimary tumor-bearing segments, and 4 had metastases in both. Of the 10 patients with segmental lymph node metastases, 7 had metastases in both lobar-hilar and mediastinal lymph nodes, and 3 of 8 with adenocarcinoma had a tumor 2.0 cm or less. CONCLUSIONS: Segmentectomy seems more favorable than wedge resection, but the risk of remnant tumor remains as compared with lobectomy. Evaluation of lobar-hilar or mediastinal lymph nodes is helpful to determine the presence or absence of segmental lymph node metastases. Limited resection can be undertaken with smaller tumors to allow preservation of more lung function while accepting a somewhat enhanced risk of recurrence.

Adenocarcinoma↗

PubMed2000

Absolute ethanol and 5% ethanolamine oleate are comparable for sclerotherapy of esophageal varices.

BACKGROUND: Endoscopic sclerotherapy is widely accepted as an effective treatment for the eradication of esophageal varices in patients with portal hypertension and a history of upper gastrointestinal bleeding. The objective of this study was to assess the effectiveness and safety of absolute ethanol as an alternative sclerosing agent to the commonly used 5% ethanolamine oleate. METHODS: One hundred fifty-seven patients with portal hypertension and a history of variceal bleeding were randomly assigned to sclerotherapy with absolute ethanol (n = 66) or 5% ethanolamine oleate (n = 91) between January 1992 and July 1994. Once eradication was achieved, these patients were prospectively followed until September 1998. RESULTS: Sclerotherapy with both sclerosants resulted in similar eradication rates (approximately 90%), with comparable numbers of sessions required for eradication (5.4 and 5.9 sessions for absolute ethanol and 5% ethanolamine oleate, respectively). Similar complication and recurrent bleeding rates were observed among both groups. CONCLUSION: Sclerotherapy with absolute ethanol is as effective as with 5% ethanolamine oleate in preventing further bleeding in patients with portal hypertension.

Adult↗