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Biomedical subjects

H Aoki

Publications and source records attributed to H Aoki.

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

The ribosome as affinity matrix': efficient purification scheme for translation factors.

A convenient method to purify each of the non-ribosomal proteins required to translate a native mRNA in vitro is described. In this scheme, the ribosome is used as an 'affinity' matrix to selectively elute the non-ribosomal proteins required for translation that are bound to these particles. Different sets of these proteins can be eluted with solutions of Mg2+ and NH4+ of various concentrations from either 70S, or 30S and 50S particles. A scheme for the purification of each initiation, elongation and release factor and 20 aminoacyl-tRNA synthetases is described. Specific examples of the purification of the initiation (IF-1, IF-2, IF-3) and elongation (EF-Tu and EF-G) factors and for a protein called 'rescue', which affects the association of native ribosomal subunits, are given. A scheme for the purification of EF-P, which stimulates peptide-bond synthesis and one of the W proteins, which permit reconstitution of translation is also described. The procedure markedly simplifies the isolation, in homogeneous form, of all the non-ribosomal proteins required to reconstruct translation.

Amino Acyl-tRNA Synthetases↗
PubMed1996

Plasma brain natriuretic peptide concentrations predict survival after acute myocardial infarction.

OBJECTIVES: This study sought to examine whether plasma brain natriuretic peptide levels can predict prognosis after myocardial infarction. BACKGROUND: It has been suggested that concentrations of plasma brain natriuretic peptide reflect left ventricular function. Although the prognosis after myocardial infarction depends on residual left ventricular function, it is not known whether plasma levels of brain natriuretic peptide after the onset of myocardial infarction can be used to predict long-term outcome. METHODS: Plasma brain natriuretic peptide and atrial natriuretic peptide levels as well as invasive hemodynamic variables were measured in 70 patients with acute myocardial infarction (53 men, 17 women; mean age 65 years). Measurements were obtained on admission (mean 6 h after onset) and on day 2 after onset. Mean follow-up period was 18 months. RESULTS: Plasma brain natriuretic peptide levels measured on admission and day 2 correlated significantly with hemodynamic variables, which are influenced by left ventricular function. However, plasma atrial natriuretic peptide levels correlated with none of the hemodynamic variables measured on admission; and of those measured on day 2, plasma atrial natriuretic peptide levels correlated only with left atrial filling pressure. During the follow-up period (mean 18 +/- 7 months), 11 patients died of cardiac causes. By Kaplan-Meier analysis, it was found that patients with plasma brain natriuretic peptide levels higher than the median level, both on admission and on day 2, had significantly higher mortality rates than those with the submedian level (on admission, p < 0.01; on day 2, p < 0.05). However, only the plasma atrial natriuretic peptide level obtained immediately after admission was significantly related to survival (p < 0.01). By Cox proportional hazards model analysis of the noninvasive variables, it was found that plasma brain natriuretic peptide concentration was more closely related to survival after myocardial infarction (p = 0.0001). CONCLUSIONS: Increased plasma brain natriuretic peptide concentrations in the early or subacute phase of myocardial infarction are a powerful noninvasive indicator of poor prognosis, possibly reflecting residual left ventricular function after myocardial infarction.

Aged↗
PubMed1996

Studies on the site of ethanol action in inducing prolactin release in male rats.

Hypersecretion of prolactin (PRL) has been implicated as one of the factors that mediate ethanol-induced hypogonadism, but the site(s) in the central nervous system where ethanol acts to lead to the stimulation of PRL secretion is unknown. To clarify the site(s) of ethanol action, medial basal hypothalamic deafferentation (MBHD) or medial basal hypothalamic ablation (MBHA) were performed stereotaxically in male rats, and their PRL secretory capacity in response to acute ethanol administration was compared with that of intact or sham-operated controls. In intact control rats, plasma immunoreactive PRL concentration increased markedly (P < .001 v saline injection) following ethanol 400 to 500 mg/100 g body weight (BW) intraperitoneally (IP). The PRL response was dose-related and reached a maximum plateau level at 15 minutes. Plasma PRL returned to a near-basal level by 60 minutes. The response was blocked completely (P < .001) by pretreatment with dopamine (1 mg per rat), a specific inhibitor of adenohypophyseal PRL secretion. In sham-operated rats and in MBHD and MBHA rats, ethanol (500 mg/100 g BW IP) induced a significant (P < .001 to .05) elevation of PRL relative to the respective saline treatment. The basal level was significantly (P < .005) lower in the MBHD group (5.3 +/- 0.9 ng/mL) and significantly (P < .001) higher in the MBHA group (101.1 +/- 15.7 ng/mL) than in the sham group (17.2 +/- 5.9 ng/mL). These results suggest the following: (1) acute ethanol administration stimulates PRL secretion from the pituitary in a dose-related manner, (2) ethanol appears to have direct stimulatory effects on adenohypophyseal PRL secretion, and (3) extrahypothalamic brain areas exert a stimulatory influence and the hypothalamus an inhibitory influence on basal PRL secretion.

Animals↗
PubMed1996

In vitro contraction of the canine corpus cavernosum penis by direct perfusion with prolactin or growth hormone.

PURPOSE: It is well established that hyperprolactinemia, most typically seen in prolactinoma patients, causes hypogonadism and impotence. There seems to be a good possibility that hyperprolactinemia causes impotence, at least partially via some intrinsic property of prolactin (PRL), rather than through its suppressive effects on the hypothalamic-pituitary-gonadal testosterone dynamics. In the present investigation, we used an in vitro canine model to attempt to clarify whether direct action of PRL on the corpus cavernosum penis may lead to erectile insufficiency. Growth hormone (GH) and placental lactogen (PL), both having close structural and functional homologies to PRL, were also studied. MATERIALS AND METHODS: Isometric tension measurement with cavernous strips was performed in the presence or absence of 10(-5) to 10(-9) M. PRL, GH, or PL in the perfusion medium. The tension change induced by the test substances was normalized relative to that induced by 120 mEq KCl. RESULTS: Both PRL and GH produced dose-related elevations (p < 0.01) of the cavernous tension, whereas PL and thiol-cleaved PRL in comparable doses were without effect (p > 0.05). When the tension rise produced by 120 mEq KCl was taken as 100%, the maximum contractions produced by PRL and GH were 80% and 110%. The minimum effective concentration was 10(-8) to 10(-7) M. for both PRL and GH. Pretreatment with indomethacin (10(-5) M.), but not tetrodotoxin (10(-5) M., partially suppressed (p < 0.05) the effects of PRL. CONCLUSION: These results suggest that PRL and GH directly and specifically produced contraction of the corpus cavernosum penis, resulting in erectile insufficiency, and that the effect of PRL is partially mediated by prostaglandin.

Animals↗
PubMed1996

Elevation of interleukin 1 receptor antagonist in the stratum corneum of sun-exposed and ultraviolet B-irradiated human skin.

Keratinocytes produce not only interleukin 1 (IL-1) but also IL-1 receptor antagonist (IL-1ra), a competitive inhibitor of IL-1. Because little is known about the presence of IL-1ra in the stratum corneum, we examined the content of IL-1ra in the stratum corneum, especially the balance between IL-1 and IL-1ra. IL-1 alpha and IL-1ra, but not IL-1 beta, were detected in the tape-stripped stratum corneum of healthy volunteers by enzyme-linked immunosorbent assays. IL-1 alpha and IL-1ra were bioactive as determined by thymocyte co-stimulation assay, and their molecular masses were 17 and 20 kDa, respectively, suggesting that the stratum corneum contains active forms of IL-1 alpha and IL-1ra produced by keratinocytes. The stratum corneum of an unexposed area, the inner side of the upper arm. contained more IL-1 alpha than a sun-exposed area, the face. In contrast, the stratum corneum of the sun-exposed area contained a markedly higher amount of IL-1ra than that of the unexposed area. The ratio of IL-1ra to IL-1 alpha was 8 in the unexposed area, and over 100 in the sun-exposed area. Therefore, IL-1 alpha activity was dominant in the unexposed area, and in contrast, IL-1ra activity was dominant in the sun-exposed area. An elevated level of IL-1ra was detected in the stratum corneum of the sun-exposed area independently of age. In the unexposed area, however, IL-1a increased, but IL-1ra decreased, with age, resulting in a significant decline of the ratio of IL-1ra to IL-1a with increasing age. Irradiation of 2 MED of ultraviolet B to the back skin, an unexposed area, resulted in striking elevation of IL-1ra in the stratum corneum in desquamating scales. These data suggest that IL-1ra in the epidermis may be inducible by chronic UV irradiation, although IL-1ra production in the epidermis may decrease with aging in the absence of any stimulus. IL-1ra in the epidermis may play a role in the regulation of IL-1-induced inflammatory responses, and an appropriate balance between IL-1 and IL-1ra may help to maintain homeostasis of the skin.

Adolescent↗
PubMed1996

Frozen-section services by telepathology: experience of 100 cases in the San-in District, Japan.

The early experience is reported here of the use of intra-operative frozen-section service by telepathology using the integrated Service Digital Network (ISDN), a commercially available system that is being connected between the Department of Pathology of Tottori University and Matsue City Hospital, a distance of 30 km. The transfer rate is currently 64 kbit/s. The frozen-section service was conducted for a total of 117 tissue specimens (organs) from 100 patients between August 1993 and May 1995. The average time taken for examination of each specimen of frozen section was 13 min, ranging between 2 and 42 min. The average number of transmitted images was 6.2. Six cases necessitated more than 11 transmitted images to make a diagnosis, while 13 cases could be diagnosed from two images only. Correct and permissible diagnoses were obtained in 109 (93.2%) out of 117 specimens when comparing the telepathology diagnosis with that of direct microscopy. Improper or misdiagnosis was made for eight cases (specimens), which were misinterpreted as papillary carcinoma in Basedow's disease, adenoma and hyperplasia in two pheochromocytomas, solid-tubular carcinoma in phyllodes tumor, mastopathy in invasive carcinoma, metastatic carcinoma in astrocytoma, follicular lymphoma in reactive hyperplasia, and lymphadenitis in follicular lymphoma. In retrospect, diagnosis of these cases should have been deferred. From the results, it was concluded that the intraoperative frozen-section service by telepathology may be a worthwhile substitute for hospitals with limited accessibility to local pathology service, in spite of pitfalls in some cases. Well prepared, high-quality frozen section, sufficient verbal communication with surgeons, and a rather conservative attitude on the part of a well-trained pathologist seem to be the essential ingredients for reaching an accurate decision when using telepathology.

Computer Communication Networks↗
PubMed1996

Mechanisms of veno-occlusion within and outside the canine corpus cavernosum penis using a pressure-flow technique and cavernoso-venography.

BACKGROUND: Physiological erection of the penis requires multiple mechanisms causing an increase in the arterial blood influx into, and decrease in the venous drainage out of the cavernous space. METHODS: We investigated the extent and location of the venous occlusion that occurs with penile erection within (intrinsic mechanism) and outside (extrinsic mechanism) the corpus cavernosum penis, using 15 adult male mongrel dogs. Under controlled flows produced by a combination of aortic ligation and constant infusion of saline into the corpus cavernosum penis, or into the deep dorsal vein, pressures within the cavernous space or deep dorsal vein were measured before and after electrical stimulation of the pelvic splanchnic (pelvic nerve), the hypogastric, and pudendal nerve. An increase in pressure following nerve stimulations represented an increase in outflow resistance due to occlusion of the venous system. Pre-and post-stimulation radiologic evaluations were performed to determine the site(s) of venous occlusion. RESULTS: Unilateral stimulation of the pelvic nerve caused leftward shift of the corporeal pressure-flow curve. Bilateral stimulation of the pudendal nerve caused a marked rise in deep dorsal vein pressure. CONCLUSIONS: Both intrinsic and extrinsic venous occlusion mechanisms exist and that the former is activated primarily by unilateral stimulation of the pelvic nerve and the latter by bilateral stimulation of the pudendal nerve. The occlusion site for the extrinsic mechanism was localized to where the dorsal vein penetrates the muscles at the base of the pelvis, whereas the precise site for the intrinsic mechanism could not be determined.

Animals↗
PubMed1996

Molecular diagnosis of hepatitis C viral infection.

With the evolution of confirmatory assays for hepatitis C viral infections, bulk populations of unknown hepatitis were diagnosed as hepatitis C virus (HCV)-mediated chronic liver dysfunction throughout the world. More recently, several systems for molecular diagnosis of hepatitis C viral infections were developed. These are commonly performed for efficient antiviral therapy using interferon. Now we are at the crossroads studying hepatitis virology for the development of sensitive and powerful treatment against HCV-mediated chronic liver dysfunction. Here we introduce the current strategy for the advanced diagnosis of hepatitis C viral infection and discuss the exploration of novel hepatitis viruses.

Flaviviridae↗
PubMed1996

Angiotensin II induces ovulation and oocyte maturation in rabbit ovaries via the AT2 receptor subtype.

The present study was undertaken to investigate the role of angiotensin II (Ang II) in ovulation and ovarian steroidogenesis and prostaglandin (PG) production via the Ang II receptors in rabbit ovaries. In in vitro perfused rabbit ovaries, PD123319, a selective nonpeptide antagonist for AT2 receptors, reduced the Ang II-induced ovulation in a dose-dependent manner, whereas CV-11974, a selective nonpeptide antagonist for AT1 receptor, did not affect the Ang II-induced ovulation. Ang II also significantly stimulated the meiotic maturation of ovulated ova and follicular oocytes in the absence of gonadotropin. The addition of PD123319 at 10 (-6) M to the perfusate significantly inhibited the Ang II-induced oocyte maturation. Ang II did not stimulate the production of progesterone by perfused rabbit ovaries but significantly stimulated the production of estradiol (E2) and PGs. When PD123319 at 10(-6) M was added to the perfusate 30 min before the onset of Ang II administration, the Ang II-stimulated production of E2 and PGs was significantly blocked. Saralasin, a peptide analog of Ang II, inhibited the specific binding of [125I] iodo-[Sar1, Ile8] Ang II to rabbit ovarian membranes in a concentration-dependent manner, yielding an inhibitory constant (IC50) value of 1.58 x 10(-9) M. PD123319 and CV-11974 also inhibited the binding of [125I]iodo-[Sar1, Ile8] Ang II; however, PD123319 and CV-11974 were 15 and 40 times less potent than saralasin, respectively. Autoradiographic study revealed that an intense localization of Ang II receptors in the rabbit ovaries was present in the granulosa cell layers and the stroma of the preovulatory follicles. AT2 receptors were predominantly located in granulosa cells, whereas AT1 receptors were more concentrated in the stroma and thecal cell layers. In summary, Ang II induced ovulation and oocyte maturation and stimulated the production of E2 and PG by perfused rabbit ovary in vitro via the AT2 receptor. Thus, locally produced Ang II may be part of a novel intraovarian paracrine or autocrine control mechanism during the ovulatory process.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1996

Two components of cell-bound isopullulanase from Aspergillus niger ATCC 9642--their purification and enzymatic properties.

Cell-bound isopullulanase (pullulan 4-glucanohydrolase: EC 3.2.1.57, IPU) from Aspergillus niger ATCC9642 [Y. Sakano et al., Denpun Kagaku, 37, 39-41 (1990)] was separated into two active components, IPU F1 (pI = 5.0) and IPU F2 (pI = 4.9), using a Mono-P HR 5/20 column. The substrate specificity on pullulan and panose, specific activity, optimum pH, pH stability, and susceptibility to certain chemical reagents were similar between IPU F1 and IPU F2. IPU F1 and F2 had an identical N-terminal amino acid sequence, A-V-T-A-D-N-S-Q-L-L. However, IPU F1 contained more total carbohydrate (15.3%) than IPU F2 (12.4%). SDS-polyacrylamide gel electrophoresis showed that the molecular weight of IPU F1 (71,000) was greater than that of IPU F2 (69,000). After deglycosylation of IPU F1 and F2 with peptide-N-glycosidase F, the molecular weights of IPU F1 and F2 became 59,000.

Amino Acid Sequence↗
PubMed1996

Immunohistochemical characterization of monoclonal antibodies (PDs) as markers of the periderm in the developing chicken embryo.

The outermost surface cell layer of the developing embryo, the periderm, arises from the initial single layer of ectoderm and is eventually exfoliated from the stratified epidermis, which has the same ectodermal origin. In this study, monoclonal antibodies against chicken limb bud ectoderm were generated and screened for those which stained the periderm. Four separate antibodies termed PD2, 3, 7 and 9 were obtained from 180 mixed hybridomas. These PD antibodies stained the periderm selectively at all stages examined (stage 20-42). By correlating the results of immunohistochemistry with observations made by transmission electron microscopy, it was revealed that PD antibodies stained both the squamous periderm at an early stage and rounded bulging peridermal cells just before exfoliation. Therefore we feel that PD antibodies may be useful in further systematic investigations of the development and function of the chicken embryonic periderm.

Animals↗
PubMed1996

[Etiology and hemodynamics of esophago-gastric varices].

The hemodynamics of the portal area, particularly of the left gastric vein in cases of esophago-gastric varices with portal hypertension have revealed that only one-third are featuring hepatofugal collateral flow (Type I), while hepatopetal and/or to and fro flow (Type II) forms make up about two-thirds. Furthermore, regarding the supply of blood to the varices, in all cases a contribution of arterial blood inflowing through the left gastric artery to the upper part of the stomach was found. Therefore, concerning the etiology of varices other than that due to hepatofugal collaterales, a hyperdynamic state of the upper part of the stomach area has been considered as an important factor. With regard to the micro-circulation of the gastric wall, it was proved that the hyperdynamic state was caused by an increase in submucosal arterio-venous anastomoses, and this was concluded to be directly responsible for the etiology of the varices. Therefore, the appropriate therapeutic approach to varices should as the rule be based on interruption both of hepatofugal collaterales and arterial flow, or the drainage of the hypertensive state of the local venous system.

Adult↗
PubMed1996

[PT-INR as a parameter for anticoagulant therapy after valve replacement surgery].

We retrospectively analyzed the intensity of anticoagulant therapy in the 195 patients who underwent valve replacement surgery with mechanical valves. An optimal level or target range of prothrombin time-international normalized ratio (PT-INR) was sought. Previously, we employed a range of 10 to 25% of thrombotest value, which corresponded to the range of 1.5 to 3.5 of PT-INR value. In one patient who underwent mitral valve replacement, PT-INR valve was 1.72 when he developed an episode of cerebral thromboembolism. There was no tendency in PT-INR value in 51 patients who developed non-critical bleeding. As a while, PT-INR value was over 4.0 in 2 patients who required a in-hospital treatment for major bleeding complications. Based on our experience, we recommend a range of 2.0 to 3.0 of PT-INR value after valve replacement surgery with mechanical valves.

Adult↗
PubMed1996

[Effects of pulmonary rehabilitation on vital capacity in patients with chronic pulmonary emphysema].

To evaluate the effects of pulmonary rehabilitation on pulmonary function, 15 patients with chronic pulmonary emphysema underwent pulmonary rehabilitation for six weeks as inpatients. Pulmonary rehabilitation consisted of relaxation techniques, breathing retraining, thoracic massage, physical exercise, and walking. In 8 of the 15 patients vital capacity increased by more than 200 ml (over 10%), and in 7 of the 15 patients the load of maximal exercise increased by more than 5 watts (over 10%). Increases in vital capacity were not associated with increases in maximal exercise load. The percent change in vital capacity associated with pulmonary rehabilitation correlated significantly with the percent change in tidal volume and the percent change in expiratory minute ventilation at the maximal load. The percent change in tidal volume at the maximal load correlated significantly with the percent change in maximum oxygen uptake. We attribute the increase in vital capacity to an improvement in thoracic cage movement. These findings suggest that pulmonary rehabilitation can increase vital capacity in some patients with chronic pulmonary emphysema, and that such an increase is not directly connected to increases in exercise capacity.

Aged↗
PubMed1996

[Psychological and physiological changes accompanying pulmonary rehabilitation in patients with chronic pulmonary emphysema].

In 14 patients with chronic pulmonary emphysema, the relations between changes in psychological status associated with pulmonary rehabilitation and exercise tolerance were studied with the Cornell Medical Index and the Yatabe-Guiford Personality Inventory. Although the scores on the latter did not change, the cardio-respiratory score on the Cornell Medical Index improved significantly (p < 0.05). The only index of exercise tolerance that improved significantly was the distance walked in 10 minutes (p < 0.05). The changes in the scores of "Lack of Objectivity" and "Rhathymia" correlated negatively with the change in the distance walked in 10 minutes (R = -0.80, p < 0.01; R = -0.81, p < 0.01). The change in psychological status that accompanied pulmonary rehabilitation has been related to the improvement in the distance walked in 10 minutes.

Aged↗
PubMed1996

[Primary right atrial hemangiosarcoma manifesting as cardiac tamponade: a case report with transesophageal echocardiography].

A 39-year-old woman presented with a right atrial hemangiosarcoma manifesting as cardiac tamponade with complaints of chest discomfort and dyspnea. Transthoracic echocardiography revealed remarkable pericardial effusion and a right atrial mass. Transesophageal echocardiography disclosed the tumor extending into the right atrial cavity. Surgery found the tumor was poorly demarcated, immobile and adhered to the adjacent right atrial wall and septum. The echocardiographic findings correlated well with the surgical and autopsy findings.

Adult↗