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Biomedical subjects

M Miyamoto

Publications and source records attributed to M Miyamoto.

At least 469 records · Page 26Linked to original sources
PubMed1988

[Levels of plasma cyclic AMP in cardiac surgery].

The actions of hormones such as catecholamines, vasopressin and growth hormones are mediated by a common intracellular second messenger, cyclic AMP (adenosine 3',5'-monophosphate). The effects of cardiac surgery on plasma cyclic AMP were studied in 32 adults patients with aorta-coronary bypass or with valvular disease. Blood specimens were obtained before operation, at the beginning and at the end of the cardiopulmonary bypass, 1, 3, 6, 9, 12, 24, 48, 72, 168 hours after surgery. The plasma cyclic AMP level during cardiac operation was elevated above the preoperative level. High levels of plasma cyclic AMP were found both in the aorta-coronary bypass and in the valvular disease immediately after the end of cardiopulmonary bypass. The plasma cyclic AMP level in patients undergoing aorta-coronary bypass with aortic clamping time more than 60 minutes was 38.6 +/- 11.7 pmol/ml, compared to 25.6 +/- 6.6 pmol/ml with aortic clamping time less than 60 minutes immediately after the end of cardiopulmonary bypass. In patients undergoing valve replacement and/or commissurotomy with aortic clamping time more than 60 minutes, the plasma cyclic AMP level immediately after the end of cardiopulmonary bypass was 113 +/- 63.3 pmol/ml, compared to 45.4 +/- 10.3 pmol/ml with aortic clamping time less than 60 minutes (p less than 0.01, Student's t test). During 24 hours after cardiac surgery, the plasma cyclic AMP concentration returned to normal range. It is considered that the plasma cyclic AMP level reflects the risk of cardiac surgery in response to homeostatic derangement.

Cardiac Surgical Procedures↗
PubMed1988

Lumbar degenerative kyphosis. Clinical, radiological and epidemiological studies.

We suggest that lumbar degenerative kyphosis be included as one of the abnormal sagittal curvatures in which a kyphosis or a marked loss of lordosis is seen in the lumbar spine, caused by degenerative changes in middle-aged and elderly. One hundred and five consecutive patients were investigated, most of whom complained of low-back pain, often with a long history. They all walked in a forward bending posture, either all the time or only when exhausted. In roentgenograms, most cases showed a marked loss of the sacral inclination, as well as multiple disc narrowing and/or vertebral wedging in the lumbar region. These subjects showed a definite weakness of the lumbar extensors compared to the flexors, and therefore a reversed ratio of extensors/flexors muscle power compared with normal controls and other types of spinal curvatures. Weakness of the lumbar extensors was clearly shown by isokinetic measurement and a marked atrophy of these muscles with fatty infiltration was demonstrated by CT scanning.

Aged↗
PubMed1988

Cardiac transplantation without cardiopulmonary bypass: experimental model to study growth of the transplanted heart.

An experimental model using surface-induced (20 degrees C) deep hypothermia and total circulatory arrest instead of cardiopulmonary bypass was developed for the study of growth of the transplanted heart. Autotransplantation of the heart was performed in 42 young dogs weighing from 4.4 to 9.0 kg (mean, 6.9 kg). Time of ischemia ranged from 26.0 to 60 minutes (mean, 43.4 minutes). Return of satisfactory cardiac function occurred in all but one animal. An early high mortality rate was due primarily to pulmonary complications, but with modifications to the technique, long-term survival increased to 70%. Early deaths (5 days to 13 weeks) of five dogs during preliminary trials were due to pleural effusion (2), sepsis (1), endocarditis (1), and ascites (1). There have been 14 long-term survivors (range, 194 to 498 days; mean, 264 days). Long-term survivors appear well, are active, and show satisfactory growth. This experimental model eliminates the need for heparinization and reduces the potential for complications associated with cardiopulmonary bypass in the dog. It avoids cannulations that might impinge on anastomotic sites. This model appears to be suited for studying growth of the transplanted heart.

Animals↗
PubMed1988

Regulation of cytokine gene expression: gene activation in type I IFN and IL-2 systems.

Cytokines represent essential soluble mediators in cell-to-cell communication and they are known to play crucial roles in many biological processes, including viral infection, inflammation and immunity. We have been focusing on two cytokine systems, the interferon (IFN) and interleukin 2 (IL-2) systems each of which respectively plays a key role in viral infections and the immune response. In both cases, expression of those cytokines and, in the case of IL-2 system, the receptor is tightly regulated at the transcriptional level. Recent studies in our laboratory as well as others have uncovered the mechanism(s) operating in the regulation of those genes and have provided further insights on how the two cytokine systems operate and what is the biological significance of gene regulation in these systems. Here, we summarize the current understanding of the IFN system and IL-2 system in the context of host defense against viral infections and T cell neoplasms, respectively.

Amino Acid Sequence↗
PubMed1988

Ischemic myocardial protection. Comparison of nonoxygenated crystalloid, oxygenated crystalloid, and oxygenated fluorocarbon cardioplegic solutions.

This study was designed to compare myocardial protection with a nonoxygenated crystalloid solution, an oxygenated crystalloid solution, and an oxygenated fluorocarbon cardioplegic solution. Postischemic ventricular performance was studied in three equal (N = 7) groups of dogs subjected to 120 minutes of global ischemia induced at an average myocardial temperature of 18.5 degrees +/- 1.4 degrees C (range 17.0 degrees to 21.0 degrees C). Left ventricular global and regional function was evaluated by sonomicrometry and micromanometers before ischemia and at 45 and 60 minutes after ischemia. Stroke volume index, left ventricular pressure-minor external diameter loop area, percent shortening, first derivative of left ventricular pressure, mean velocity of circumferential fiber shortening, and the slope of the end-systolic pressure were used to evaluate myocardial contractility. In vitro oxygen content of the three cardioplegic solutions was measured at a mean injection temperature of 8.3 degrees +/- 0.6 degrees C: 0.8 +/- 0.1 vol% (nonoxygenated crystalloid cardioplegia), 3.2 +/- 0.2 vol% (oxygenated crystalloid cardioplegia), and 6.2 +/- 0.2 vol% (oxygenated fluorocarbon cardioplegia). Recovery of global and regional function was significantly (p less than 0.05) better with both oxygenated solutions than with the nonoxygenated solution. Differences between the oxygenated crystalloid and fluorocarbon groups were not significant. We conclude: (1) Compared to nonoxygenated crystalloid cardioplegia, oxygenated crystalloid and oxygenated fluorocarbon cardioplegic solutions gave superior myocardial protection during 2 hours of ischemic arrest; (2) no difference was found in protective effects between an oxygenated crystalloid and an oxygenated fluorocarbon solution.

Animals↗
PubMed1987

Characteristics of memory impairment following lesioning of the basal forebrain and medial septal nucleus in rats.

Memory impairment in rats with lesions of the basal forebrain (BF) and medial septal nucleus (MS) including cell bodies of the cortical and septohippocampal cholinergic systems, respectively, were compared in order to evaluate the functional contribution of the two cholinergic systems to memory. Biochemical assay revealed that lesioning of the BF and MS resulted in marked and selective decreases in both choline acetyltransferase and acetylcholinesterase activities in the cerebral cortex and hippocampus, respectively. Rats with BF lesions exhibited a severe deficit in a passive avoidance task; acquisition of passive avoidance by repeated training was sluggish, and the acquired response was rapidly eliminated in a subsequent extinction test. However, only slight impairment of passive avoidance was observed in rats with MS lesions. Memory impairment in rats with BF or MS lesions was also investigated using two spatial localization tasks, the Morris water task and the 8-arm radial maze task. Both BF and MS lesions elicited a significant impairment in the Morris water task that required reference memory, as demonstrated by an apparent increase in the latency to escape onto a hidden platform in a large water tank. The impairment was much more obvious in the BF-lesioned rats. In contrast, in the radial maze task primarily requiring working memory, rats with lesions of the MS showed severe disruption, exhibiting a marked increase in total errors, a decrease in the number of initial correct responses, and an apparent change in the strategy pattern. However, corresponding changes in the rats with BF lesions were slight. These results suggest that BF lesions may lead to substantial long-term memory impairment while MS lesions may primarily produce short-term or working memory impairment, indicating a qualitatively different contribution of the two cholinergic systems to memory. It is also suggested that these two experimental animal models may be useful for evaluation of therapeutic drugs for senile dementia of the Alzheimer type.

Acetylcholinesterase↗
PubMed1987

Biological effect of anti-fucosyl GM1 ganglioside antibody on cyclic adenosine 3',5'-monophosphate production in FRTL5 rat thyroid cells.

Addition of specific anti-fucosyl GM1 antibody raised in a rabbit caused dose-dependent inhibition of endogenous and thyrotropin (TSH)- or thyroid stimulating antibody-stimulated cyclic adenosine 3',5'-monophosphate (cAMP) production in cultured FRTL5 rat thyroid cells. Further, the antibody inhibited the cAMP increase induced by prostaglandin E1 and forskolin. However, anti-fucosyl GM1 antibody did not affect the binding of [125I]bovine TSH to solubilized porcine thyroid TSH receptor or to FRTL5 cells. In conclusion, fucosyl GM1 is one of the specific membrane components of thyrocytes and appears to be involved in adenylate cyclase stimulation or cAMP generation. Further, the biological effects of the ganglioside do not seem to be mediated by the TSH receptor, suggesting a post receptor mechanism.

Alprostadil↗