Periodic isorhythmic dissociation during enflurane anesthesia in a patient with Sinus Bradycardia

Key words  dysrhythmia - isorhythmic dissociation - oscillation     

Study on the developing potentiality of mouse morula produced in vitro or in vivo after vitrification

Great horovement haS been made in the cryopreservation Of inalnlnalian elnbmp since wnttingham['] reported his Pioneering wold about successful cryOPreservationof mouse embryo. It results in the availability of cryOPreserVation of embryos of all stages[']. HOwever, cryopreserved embryos can not avoid the damages by ice crystal,which is a major cause of cen death in the freezing andthawing ProceduresL',']. SO it is necesseq to seareh for anew and more efficient method for embryO cryOPrese…     

Inhibition of Ca2+ channel current by μ- and κ-opioid receptors coexpressed in Xenopus oocytes: desensitization dependence on Ca2+ channel α1 subunits

1. Desensitization of μ- and κ-opioid receptor-mediated inhibition of voltage-dependent Ca²⁺ channels was studied in a Xenopus oocyte translation system.
2. In the oocytes coexpressing κ-opioid receptors with N- or Q-type Ca²⁺ channel α₁ and β subunits, the κ-agonist, U50488H, inhibited both neuronal Ca²⁺ channel current responses in a pertussis toxin-sensitive manner and the inhibition was reduced by prolonged agonist exposure.
3. More than 10 min was required to halve the inhibition of Q-type channels by the κ-agonist. However, the half-life for the inhibition of N-type channels was only 6±1 min. In addition, in the oocytes coexpressing μ-opioid receptors with N-type or Q-type channels, the uncoupling rate of the μ-receptor-mediated inhibition of N-channels was also faster than that of Q-type channels.
4. In the oocytes coexpressing both μ- and κ-receptors with N-type channels, stimulation of either receptor resulted in a cross-desensitization of the subsequent response to the other agonist. Treatment of oocytes with either H-8 (100 μM), staurosporine (400 nM), okadaic acid (200 nM), phorbol myristate acetate (5 nM) or forskolin (50 μM) plus phosphodiesterase inhibitor did not affect either the desensitization or the agonist-evoked inhibition of Ca²⁺ channels.
5. These results suggest that the rate of rapid desensitization is dependent on the α₁ subtype of the neuronal Ca²⁺ channel, and that a common phosphorylation-independent mechanism underlies the heterologous desensitization between opioid receptor subtypes.

     

Evaluation of a compressive-type skeletal muscle pump for cardiac assistance

BACKGROUND: Recent investigations have focused on using the latissimus dorsi muscle for cardiac assistance. Although cardiomyoplasty has been applied clinically, other procedures remain experimental, but promising, modes of cardiac assistance. We assessed the latissimus dorsi muscle as an in situ energy source for circulatory assist devices. METHODS: We developed a pneumatic chamber as a compressive-type muscle actuator. The chamber was implanted under the latissimus dorsi muscle and converted contractile power into pneumatic pressure. The effect of chamber position and size and the influence on muscle blood flow were examined. After muscle conditioning, the pump performance of a circulatory assist device driven by the chamber was evaluated. RESULTS: The chamber functioned better when placed in the proximal position of the latissimus dorsi muscle. The size affected the generated pneumatic pressure, and the higher resting pressure of the chamber reduced the muscle blood flow. The maximum stroke work of the circulatory assist device was greater than that of the right ventricle but less than that of the left ventricle. The chamber could drive the circulatory assist device against the systemic range of afterload in which a high preload was available. Long-term adhesion surrounding the chamber reduced the pressure generation capability. CONCLUSIONS: The compressive-type muscle actuator using the latissimus dorsi muscle generated acceptable hemodynamic work for right ventricular bypass or aortic counterpulsation.     

The investigation of age-specific PSA reference range as the cut-off values in the mass screening for prostatic cancer

BACKGROUND: The objective of this study is to determine age-specific PSA reference ranges in Japanese healthy men and investigate the effectiveness of these ranges as the cut-off values in the mas screening for prostatic cancer. METHODS: The study included a total of 5,206 male aged from 55 to 89 years old who wished to submit the mass screening for prostatic cancer in an urban area of Kyoto in 1995-1997, but had no evident prostatic cancer. We measured serum PSA levels by the filter paper method (Delfia PSA kit). RESULTS: We found the increase in serum PSA levels with the advancing age. With the 95th percentile for serum PSA as the upper limit, the age-specific PSA reference ranges were determined to be 2.1 ng/ml for patients aged 55 to 59 years old, 3.2 ng/ml for 60 to 69 years old, 4.4 ng/ml for 70 to 79 years old, 6.5 ng/ml for 80 to 89 years old. If we used these ranges as the cut-off values in the mass screening this time, five cases from 76 to 89 years old of prostatic cancer were overlooked. CONCLUSIONS: We found the increase in serum PSA levels with advancing age. But the positive proof of using this range to a mass screening for prostatic cancer was not certified, because time incidence of prostatic cancer in the examinees was uncertain and there is a possibility of overlooking some cases.     

Roles of CD4+ and CD8+ T cells in discordant skin xenograft rejection

An essential role of murine CD4+ T cells in immune reactivity and skin graft rejection in discordant xenogeneic combinations have been reported. Our study was conducted to further clarify the roles of CD4+ and CD8+ T cells in discordant skin xenograft rejection, by using CD4 and CD8 knockout [C57BL/6 Cr Slc (B6; H-2b) background] mice. When human skins were grafted on CD8 knockout mice or B6 mice, both hosts rejected human skin grafts within 12 days after grafting. By contrast, survival of human skin grafts was significantly prolonged in CD4 knockout mice (mean survival times=19.3+/-(SD) 1.6 days; median 19 days). Fully allogeneic C3H/He Slc (H-2k) skin grafts were rejected within 14 days in CD4 knockout mice, suggesting that non-CD4+ T cells in CD4 knockout mice were immunocompetent for allograft rejection. In spleens of these recipient mice, CD8+ T cells seemed to be activated 10 days after human skin grafting. Immunohistological analysis revealed the infiltration of CD8+ T cells at the site of transplanted human skin on CD4 knockout mice. To further examine the role of CD8+ T cells in CD4 knockout mice, human skin grafting was performed on day 0 followed by administration of anti-CD8 monoclonal antibody on days 0, 5, and 14. The administration of anti-CD8 monoclonal antibodies caused the significant prolongation of human skin graft survival. These results indicate the following two conclusions: (1) CD4+ T cells have an essential role in rejecting discordant human skin xenografts rapidly and (2) however, CD8+ T cells also are capable of rejecting discordant human skin xenografts.     

Improvement of brain single photon emission tomography (SPET) using transmission data acquisition in a four-head SPET scanner

Attenuation coefficient maps (-maps) are a useful way to compensate for non-uniform attenuation when performing single photon emission tomography (SPET). A new method was developed to record single photon transmission data and a-map for the brain was produced using a four-head SPET scanner. Transmission data were acquired by a gamma camera opposite to a flood radioactive source attached to one of four gamma cameras in the four-head SPET scanner. Attenuation correction was performed using the iterative expectation maximization algorithm and the-map. Phantom studies demonstrated that this method could reconstruct the distribution of radioactivity more accurately than conventional methods, even for a severely non-uniform-map, and could improve the quality of SPET images. Clinical application to technetium-99m hexamethylpropylene amine oxime (HMPAO) brain SPET also demonstrated the usefulness of this method. Thus, this method appears to be promising for improvement in the image quality and quantitative accuracy of brain SPET.This work was presented in part at the World Congress on Medical Physics and Biomedical Engineering, 7–12 July 1991, Kyoto, Japan