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Biomedical subjects

J Masuda

Publications and source records attributed to J Masuda.

At least 55 records · Page 3Linked to original sources
PubMed1998

High oxygen delivery and extraction by perfluorocarbon-primed extracorporeal membrane oxygenation do not prevent anaerobic metabolism in rabbits.

PURPOSE: This study was designed to evaluate the advantage of perfluorocarbon (PFC) emulsion priming for venoarterial extracorporeal membrane oxygenation (ECMO) by comparison with hydroxyethyl starch (HES) solution in rabbits (2.8 to 3.9 kg). RESULTS: ECMO initiation was accompanied by a profound decrease in hematocrit (from 40.1% to 14.9%) in both groups. The arterial and the right atrial oxygen contents in the PFC group (n = 4; 38.5 and 11.5 mL/dL) were greater than in the HES group (n = 5; 7.0 and 5.1 mL/dL). Right atrial oxygen tension in the PFC group increased at the beginning of ECMO (from 38.4 to 51.2 mm Hg; P = .031) and remained higher than in the HES group for 60 minutes. These results indicate that oxygen supply and extraction in the PFC group were much greater than in the HES group. However, plasma lactate increased progressively during the 120-minute ECMO procedure in both groups (from 1.8 to 14.5 in the HES group, and from 2.3 to 12.2 in the PFC group). CONCLUSION: Perfluorocarbon priming for ECMO, although providing high oxygen delivery and extraction, does not prevent anaerobic metabolism.

Anaerobiosis↗
PubMed1998

Transient neurologic syndrome in one thousand forty-five patients after 3% lidocaine spinal anesthesia.

UNLABELLED: Recent reports have discussed the potential risk of transient radicular irritation (TRI) after spinal anesthesia with lidocaine. Because we have not encountered such neurologic sequelae with the high incidence reported, we prospectively examined the incidence of TRI after spinal anesthesia with lidocaine. One thousand forty-five adult patients (aged 47 +/- 15 yr) receiving spinal anesthesia with 3% hyperbaric lidocaine (1.0-1.5 mL) for anorectal surgery were consecutively studied. After the induction of spinal anesthesia, all patients were placed in the prone position for surgery. Patients were evaluated for neurologic symptoms in the buttocks, thighs, or lower extremities using a checklist to standardize data collection. Although there was no complaint of neurologic symptoms on Postoperative Day (POD) 1, four patients (0.4%) reported aching, hypesthesia, numbness, or dull pain of both lower extremities and buttocks by the morning of POD 3. In three patients, the symptoms resolved without any treatment by POD 5, whereas in one patient, numbness of the lower extremities lasted until POD 7. We conclude that a combination of lidocaine with surgical position or leg manipulation during surgery might be a major contributing factor in the development of transient neurologic syndrome. IMPLICATIONS: Recent studies have reported the potential risk of transient neurologic syndrome after lidocaine spinal anesthesia. The current study reports a low incidence of such sequelae in 1045 patients undergoing anorectal surgery during the prone position. Other factors, such as surgical position, may be important in the development of this syndrome.

Adult↗
PubMed1998

Abscopal regression of hepatocellular carcinoma after radiotherapy for bone metastasis.

Spontaneous regression of hepatocellular carcinoma is a rare phenomenon. Abscopal regression of tumours resulting from the effect of irradiation of a tissue on a remote non-irradiated tissue is also rare. The case of a 76 year old Japanese man with hepatocellular carcinoma that regressed after radiotherapy for thoracic vertebral bone metastasis is described. Serum levels of tumour necrosis factor-alpha increased after radiotherapy. The findings suggests that such abscopal related regression may be associated with host immune response, involving cytokines such as tumour necrosis factor-alpha.

Aged↗
PubMed1998

Effect of regular aerobic exercise on cerebrovascular tone in young women.

Our objective was to evaluate the effect of regular aerobic exercise on cerebrovascular tone in young women. Color and pulsed Doppler ultrasonography were used to determine the pulsatility index in the ophthalmic artery in 20 normotensive, nonpregnant young women (aged 19 to 26 years) with a regular menstrual cycle on cycle day 5. Blood pressure and heart rate were recorded at each examination. Blood samples were collected from all the subjects to measure serum estradiol levels and serum lipid profiles. Ten of the 20 women (exercise group) have maintained aerobic exercise for 50 min, 3 to 5 days a week, for at least a year. The other 10 women (nonexercise group) never did regular exercise. There were no significant differences between the two groups regarding age, body mass index, mean blood pressure, and heart rate and serum estradiol, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglyceride levels. The pulsatility index value (mean, 1.89; standard deviation, 0.33) of the ophthalmic artery in the exercise group was significantly lower than that (mean, 2.53; standard deviation, 0.26) in the nonexercise group. Regular aerobic exercise in young women significantly decreases the peripheral cerebrovascular tone, and this might be a favorable adaptation for early prevention of cerebrovascular disease, which is common in older women.

Adaptation, Physiological↗
PubMed1998

[Severe pulmonary hypertension due to mitral regurgitation without overt sign of congestive heart failure: a case report].

A 49-year-old man was found to have a heart murmur at a local hospital and was referred to our hospital for further examination. Although he had no signs of congestive heart failure, echocardiography and cardiac catheterization showed severe pulmonary hypertension caused by severe mitral regurgitation. Mitral valve replacement was performed, followed by reduction of pulmonary artery pressure. This patient had an unusual combination of no signs of lung congestion despite severe mitral regurgitation with pulmonary hypertension.

Echocardiography↗
PubMed1997

Mechanism of cardiac involvement in the WBN/Kob rat.

The cardiac characteristics of the WBN/Kob rat resemble those of rats with catecholamine-induced myocarditis. To determine the etiology of these WBN cardiac characteristics, we assessed the number and affinity of beta-adrenergic receptors, and investigated adenylate cyclase activity, the cardiac myocyte cyclic adenosine monophosphate (cAMP) concentration and the activity of guanosine triphosphate (GTP)-binding protein in 3-month-old WBN/Kob rats. Age-matched Wistar rats served as controls. The mean number of beta-adrenergic receptors was similar in WBN/Kob and Wistar rats (28.0+/-9.1 v 28.3+/-8.9 fmol/mg protein), and there was no significant difference in beta-adrenergic receptor affinity between groups (1.09+/-0.54 v 1.26+/-0.60 nM). The mean cAMP concentration in cardiac myocytes was significantly higher in WBN/Kob rats than in Wistar rats 1975.6+/-247.8 v 344.9+/-83.6 pmol/g wet tissue), (P=0.0112) as was adenylate cyclase activity (33.61+/-8.32 v 24.3+/-12.78 pmol/mg/min), (P=0.0174). The activity of GTP-binding protein was significantly higher in WBN/Kob rats than in Wistar rats. After a beta-agonist binds to a beta-adrenergic receptor, activated adenylate cyclase produces cAMP in myocytes, which in turn opens the Ca2+ channel, leading to an influx of Ca2+ into myocytes. Our results suggest that the increase in adenylate cyclase activity in WBN/Kob rats have led to an increase in the cAMP concentration in myocytes. This process may have resulted in excessive beta-adrenergic activity due to high activity of GTP binding protein in WBN/Kob rats, which may explain the hypersensitivity of WBN/Kob rats to isoproterenol and the development of catecholamine-induced myocarditis.

Adenylyl Cyclases↗
PubMed1997

Cardiac output and circulating blood volume analysis by pulse dye-densitometry.

OBJECTIVE: Pulse dye-densitometry (PDD) is a newly developed method for monitoring the indocyanine green (ICG) concentration in an artery with which cardiac output (CO) and circulating blood volume (CBV) can be determined. We evaluated its accuracy for clinical use. METHODS: In 7 patients under general anesthesia, ICG-sensitive optical probes (805 and 890 nm) were attached to a finger. Following injection of ICG, the arterial concentration of dye was recorded optically by the non-invasive test instrument and sampled arterial blood ICG concentration was also measured photometrically for comparison. In order to validate the PDD analysis, CO was also measured by both the dye dilution cuvette method and by thermodilution in 8 patients scheduled for coronary artery bypass grafting. In 30 other patients, CBV assessed by PDD was compared with its value estimated from body size. RESULTS: The blood dye concentration correlated well with the values obtained by PDD (r = 0.953, p < 0.01). Mean bias for the test PDD CO was +0.15 +/- 0.72 min l-1 (not significant (n.s.)) compared with the cuvette method while the mean bias of the thermodilution method vs the cuvette method was +0.79 +/- 0.84 min l-1 (p < 0.0001.). The average value of CBV obtained by PDD was 3.81 +/- 1.39 L compared with that estimated value, 3.72 +/- 0.77 L (n.s.). CONCLUSIONS: CO determined by PDD agrees well with cuvette densitometry, and somewhat less well with CO by thermodilution. The new method, by not requiring a pulmonary arterial catheter, is less invasive than either older method, and yields in addition a value of CBV.

Blood Volume↗
PubMed1997

[Apo(a) phenotype as a risk factor for the silent brain infarction].

Silent brain infarction (SBI) in the penetrating arteries is thought to be one of risk factors for overt cerebral stroke and vascular dementia. Although both Lp(a) concentration and apo(a) phenotype have been reported as risk factors for atherothrombotic infarction in cortical arteries, the roles of Lp(a) in the pathogenesis of lacunar infarction in the penetrating arteries remains controversial. We assessed the importance of apo(a) phenotype as a risk for SBI using a case control analysis. The frequency of low molecular weight phenotype (allele a) of apo(a) was significantly higher in subjects with SBI than in those without SBI. Relative risk for SBI was significantly higher in subjects with allele a than in subjects without allele a. Apo(a) phenotype was indicated to be one of the risk factors for SBI.

Adult↗
PubMed1997

Three-dimensional reconstruction of intravascular ultrasound images of coronary stents using an ECG-gated pull-back device.

Three-dimensional reconstruction (3D-R) of intravascular ultrasound (IVUS) images is not yet satisfactory because of artifacts caused by cardiac movement. This problem can be overcome with a new device, an electrocardiographic (ECG)-gated pull-back system. Using this device a catheter is pulled back stepwise gated by the ECG, and IVUS dynamic images of an entire cardiac cycle are acquired at each step. We performed 3D-R of IVUS images of stents using this new device in six patients with Palmaz-Schatz coronary stent implantation. We obtained precise 3D images in all cases, and stent structure was visualized in detail. In conclusion, use of an ECG-gated pull-back device enables precise 3D-R of IVUS images and provides useful information on the coronary artery.

Aged↗
PubMed1996

A second double-stranded RNA virus from yeast.

Two double-stranded RNA viruses exist as permanent persistent infections of the yeast Saccharomyces cerevisiae: ScVL1 and ScVLa. Both belong to the Totiviridae, which include a number of fungal and protozoan double-stranded RNA viruses. Although ScVL1 and ScVLa share the same genomic organization and mode of expression and coexist in the same cells, they show no evidence of recombination: with one limited exception, sequence conservation is detectable only in regions conserved in all totiviruses. Both have two open reading frames on their single essential RNAs: cap (encoding a capsid polypeptide) and pol (encoding an RNA-dependent RNA polymerase). The ScVLa virus, like ScVL1, appears to express its Pol domain by a -1 translational frameshift.

Amino Acid Sequence↗
PubMed1996

Wound infiltration with lidocaine prolongs postoperative analgesia after haemorrhoidectomy with spinal anaesthesia.

PURPOSE: There are few clinical data examining whether sensitization of peripheral nerves contributes to postoperative pain when the entry of noxious impulses to the central nervous system is blocked. We hypothesized that wound infiltration with lidocaine would provide better postoperative analgesia than with normal saline following haemorrhoidectomy with spinal blockade. METHODS: In a randomized, placebo-controlled, blinded study, 168 adults undergoing haemorrhoidectomy were allocated to two groups. In Group L (n = 88) local infiltration was provided with lidocaine 1% and in Group S (n = 80) with normal saline. Following spinal anaesthesia with lidocaine 3%, the surgeon infiltrated 15 ml of either infiltration solution to the surgical area. Postoperative analgesia was obtained by continuous epidural administration of 90 mg eptazocine in normal saline for 48 hr. Supplemental analgesics were given on request. Postoperative pain control was assessed at rest and during coughing with a 10 cm VAS on the 1st, 2nd, and 3rd postoperative days (POD). RESULTS: The VAS scores at rest in Group L were lower than those in Group S throughout the postoperative period. During coughing, VAS scores in Group S were increased on the 3rd postoperative day, while those in Group L remained constant (4.42 +/- 0.27 vs 3.14 +/- 0.28, P < 0.05). Fewer patients in Group L than in Group S required supplemental analgesics. CONCLUSION: Preoperative lidocaine infiltration to the surgical area provided prolonged postoperative analgesia in patients receiving haemorrhoidectomy with spinal anaesthesia.

Adult↗
PubMed1996

Monocyte-derived macrophages prime peripheral T cells to undergo apoptosis by cell-cell contact via ICAM-1/LFA-1-dependent mechanism.

We designed the present study to clarify the mechanism of superantigen-induced apoptosis of human mature T cells and to elucidate the pivotal roles of monocyte-derived macrophages in induction of T cell apoptosis. Exposure of unfractionated human peripheral blood mononuclear cells to SEA, SEB or PHA elicited apoptosis in T cells after 5-day culture. In purified T cell preparations, SEB was unable to induce apoptosis, but was inductive when the purified T cells were cocultured with monocyte-derived macrophages adhering to plastic culture dishes. Placing the T cells in the insert wells which physically separated them from the adhering macrophages resulted in a complete loss of SEB-induced apoptosis. The addition of blocking antibodies against LFA-1, ICAM-1 and CD2 to the cocultures significantly inhibited the SEB-induced T cell apoptosis. We concluded therefore that direct contact of macrophages with T cells is critical in SEB-induced T cell apoptosis, and that adhesion molecules such as LFA-1/ICAM-1 and CD2 may be involved in the mechanism of this effect.

Apoptosis↗
PubMed1996

Exercise beta-methyl iodophenyl acid (BMIPP) and resting thalium delayed single photon emission computed tomography (SPECT) in the assessment of ischemia and viability.

To clarify the significance of exercise BMIPP (beta-methyl iodophenyl pentadecanoic acid) and resting T1 delayed single photon emission computed tomography (SPECT) in the assessment of ischemia and viability, we studied maximal exercise-loading BMIPP SPECT following rest-injected T1 3 h SPECT in 11 control subjects, 20 patients with effort angina and 38 patients with old myocardial infarction. The left ventricular wall on ECT was divided into 9 segments. BMIPP and T1 uptake were scored as 0 = normal, 1 = reduced, 2 = severely reduced, or 3 = absent. Discordance was defined as when segments with a reduced BMIPP uptake had a better resting T1 uptake. Significant coronary artery stenosis was defined as stenosis of 75% or greater on coronary arteriogram. Left ventricular wall motion was assessed as either normokinesis, hypokinesis, severe hypokinesis, akinesis or dyskinesis on left ventriculogram. When discordance was considered to be a marker of ischemia, the sensitivity and specificity in effort angina and control subjects were 95.2% and 84.6% for patients and 83.9% and 94.4% for diseased vessels, respectively. There were no differences between the sensitivity and specificity in left anterior descending artery (LAD), left circumflex artery (LCx) and right coronary artery (RCA) lesions (83.3%, 95.5% in LAD, 83.3%, 95.5% in LCx, 85.7%, 92.6% in RCA, respectively). All of the patients with old myocardial infarction had reduced exercise BMIPP uptake in infarcted regions. In old myocardial infarction, 35 patients had segments with discordant uptake. Discordance was observed in 75 (91.5%) of 82 segments with hypokinesis, and in 24 (92.3%) of 26 segments with severe hypokinesis. Even among the 36 segments with akinesis or dyskinesis, 25 (69.0%) had discordant uptake. When discordance in the infarcted region was considered to be a marker of viability, regions with severe asynergy showed a high possibility of viability. Thus, discordant uptake on exercise BMIPP and resting T1 delayed SPECT may be a useful marker of ischemia in effort angina and of viability in old myocardial infarction.

Aged↗
PubMed1996

Heterogeneity in the appearance and distribution of macrophage subsets and their possible involvement in hypertensive vascular lesions in rats.

In hypertensive vascular lesions, various pathologic changes are exhibited. To clarify the mechanisms responsible for this diversity of vascular lesions, we immunohistochemically examined hypertensive vascular lesions in stroke-prone spontaneously hypertensive rats with reference to the distribution of macrophage subsets. The brain, kidney, heart, and aorta were dissected from stroke-prone spontaneously hypertensive rats and Wistar-Kyoto rats at 8, 12, 16, and 20 weeks of age. Immunohistochemistry was performed with antibodies against the macrophage markers ED1, ED2, and OX42, the MHC class II antigen marker OX6, the T-lymphocyte markers CD4, CD5, and CD8, and other markers, such as alpha-smooth muscle actin, proliferating cell nuclear antigen, and von Willebrand factor. Fibrinoid necrosis was dominant in the brain, and fibrocellular proliferative lesions were dominant in the kidney. Immunohistochemically, the decreased intensity of alpha-smooth muscle actin immunostaining preceded the formation of vascular lesions. Although preexisting ED2-positive perivascular resident macrophages completely disappeared in fibrinoid necrosis, MHC class II-negative and ED1-positive macrophages were scattered around the lesion and showed phagocytosis in the brain, which indicates that macrophages in fibrinoid necrosis had extravasated and acted only as scavengers. In the kidney, there was extensive accumulation of MHC class II-positive and ED1-positive macrophages with T lymphocytes along the affected arteries. These inflammatory cells seemed to be supplied through the perivascular interstitial space, not through the endothelium, and the accumulation of these cells preceded the development of fibrocellular proliferative lesions. In the heart and aorta, macrophage accumulation was either absent or slight, and vascular lesions were rarely observed. These findings suggest that heterogeneity in the time course of macrophage infiltration and in the distribution of macrophage subsets among the vascular trees of various organs seems to be correlated with the diversity of hypertensive vascular lesions. Differences in the routes that supply macrophages and their functions may determine the pathologic changes in the vascular lesions.

Animals↗
PubMed1996

[Identical twin sisters with IgA nephropathy].

This report described 45-year-old identical twin sisters with IgA nephropathy. Case 1 presented with microscopic hematuria and proteinuria at the age of 39. Case 2 was found proteinuria at the age of 32. Both the physical examination and laboratory data of these cases were normal. Serum level of IgA was not elevated. The renal biopsy specimen of two cases showed slight mesangial proliferation by light microscopy and mesangial IgA deposition by immunofluorescence microscopy. Their serotype for HLA was found to be HLA-A2, A24, Bw35, Cw1, Cw3, DRw8, DRw12. Several reports indicated the familial occurrence of patients with IgA nephropathy and a strong association with HLA-Bw35 in those patients. The present cases also suggested that an abnormal immune response-linked HLA system may be involved in the development of IgA nephropathy.

Diseases in Twins↗
PubMed1996

[Left ventricular pseudoaneurysm recognized 9 years after mitral valve replacement and repeated heart failure of 3 years duration: a case report].

A 66-year-old woman had suffered from repeated heart failure beginning 6 years after mitral valve replacement. Left ventricular pseudoaneurysm was discovered 9 years after the replacement, while no evidence including histology was obtained for the cause of the pseudoaneurysm except the mitral valve replacement. The progression of aortic valve stenosis and the formation of the pseudoaneurysm may have contributed to the onset of congestive heart failure. Surgical treatment was successful. Although left ventricular pseudoaneurysm after mitral valve replacement is rare, careful echocardiographic examination is necessary for detecting such a complication in patients after surgery.

Aged↗