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Biomedical subjects

Y Asano

Publications and source records attributed to Y Asano.

At least 505 records · Page 28Linked to original sources
PubMed1992

Suppression of immune responses by cloned T cells and their products.

We have established a number of IL-2 dependent T cell clones with a definite suppressor function for the antibody response. Our collection included CD4+ helper (Th) and suppressor T cell (CD4+ Ts), and CD8+ cytotoxic (Tc) and suppressor T cell (CD8+ Ts) clones. Ts clones were defined by their suppressive activity on antigen-induced proliferative response and on helper functions of other CD4+ Th clones without detectable cytotoxicity and production of known helper type interleukins. The I-J expression was found to be present on both Th and Ts clones, and was generally associated with the H-2 restriction specificity of TcR of these clones. We have shown that the activated CD4+ Ts cells could inhibit the increase of intracellular Ca2+ of Th clones induced by antigen-pulsed antigen-presenting cells (APC). The identity of MHC restriction-specificities was required for the instant suppression of Ca2+ influx of Th clones, while a longer period of activation of Ts clones was needed to suppress the response of Th clones having different MHC restrictions. A strict selectivity was found in the suppressive activity of Ts clones in that Ts clones could suppress the Ca2+ responses of Th1 or Th2 clones but not of other CD4+ Ts clones. Ts clones could suppress the Ca2+ influx of Th clones induced only by antigen-pulsed APC or anti-TcR antibody but not by Con A or IL-2. Both CD4+ and CD8+ Ts clones released soluble immunosuppressive factors upon stimulation with immobilized anti-CD3 antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Effects of Nd:YAG laser irradiation on ventricular myocardium in dogs using an artificial sapphire tip contact laser catheter].

To apply Nd:YAG laser irradiation through a new sapphire tip contact laser method to catheter ablation in treatment of tachy-arrhythmias, effects of laser irradiation on ventricular myocardium were investigated in 10 mongrel dogs. Nd:YAG lase (1064nm) discharges were delivered to different sites on the endomyocardium at power of 5, 10, 15, 20 or 25w with duration of 3, 5, or 10 seconds (sec.) respectively in closed beating hearts. Histopathologically, the lesion irradiated was clearly demarcated from the normal myocardium by the construction band necrosis zone. The depth of injured myocardium was less than 2mm with 3 sec. irradiations, with 5 sec. from 1 mm to 4 mm in proportion to power increase, with 10 sec. from 3mm to 8 mm in proportion to the power from 5w to 15w and could not be measured in cases of more than 20w irradiations. Although with every irradiation duration, the depth of injury increased in proportion to the power increase. With the same total energy, a longer time of irradiation produced deeper injury than a shorter time. This method makes it easier to keep the laser positioned to target than bare laser, and is suitable for use in catheter ablation.

Animals↗
PubMed1992

[Recurrent cases of chronic subdural hematoma--its clinical review and serial CT findings].

Eighty-eight cases (114 hematomas) of chronic subdural hematoma (SDH) were treated surgically using irrigation with or without drainage. 13 cases (14.8%), 13 hematomas (11.4%) showed recurrence after the 1st operation. They were compared with non-recurrent cases using clinical reviews and serial CT findings. The result of the study showed that all of the patients in whom recurrence occurred were male and elderly (mean age 70.4 years). Many of these recurrences occurred in cases of bilateral SDH, on the left hematoma side, and at intervals within 7 days from the onset of clinical symptoms after the 1st operation. All recurrent cases were treated surgically using irrigation without drainage. In preoperative CT findings, it was shown that high density areas and small-sized hematomas were detected at a slightly higher rate in recurrent cases than in non recurrent cases. In postoperative CT findings, it was shown that many of the recurrent patients deteriorated during an interval from 2 weeks to 2 months. It was shown that non-recurrent patients had become almost normal by 3 months after the operation. Residual air volume into the subdural space within 7 days in recurrent cases was greater than in non-recurrent cases. Therefore, using irrigation with drainage, planning the operative timing, and reduction of residual air volume into subdural space are proposed as suitable means to avoid recurrence of SDH. Patients of SDH need postoperative follow-up during an interval up to 3 months.

Adult↗
PubMed1992

[An assessment of nosocomial infections of methicillin-resistant Staphylococcus aureus based on coagulase typing and phage typing].

An epidemiologic investigation was carried out in Ogaki Municipal Hospital to clarify the status of nosocomial MRSA Infection between 1989 and 1991. In 1989, coagulase type IV, enterotoxin A-producing, and phage group I strains, which were highly resistant to multiple antibiotics and isolated in the internal wards, accounted for 43.4% of all MRSA strains clinically isolated in the entire hospital. In 1990, coagulase type II strains that were sensitive to GM but resistant to FMOX and IPM increased. There were significant differences in the frequency of detection of various strains among wards, suggesting an inter-ward variation in MRSA strains. Changes in environmental strains reflected those in clinical strains. The findings suggest the necessity of measures not only for long-hospitalized MRSA carriers themselves but also for the environment of patients, medical staff, and those taking care of patients.

Bacteriophage Typing↗
PubMed1992

Elevation of levels of carcinogenic tryptophan pyrolysis products in plasma and red blood cells of patients with uremia.

The carcinogenic tryptophan pyrolysis products, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), have been measured in plasma and red blood cells (RBC) of patients with uremia and normal subjects by using a high-performance liquid chromatography (HPLC) method. In both uremic patients and normal subjects, these carcinogens have been detected in RBC as well as plasma. Trp-P-1 and Trp-P-2 levels in plasma of uremic patients were significantly higher than those of normal subjects. Moreover, these carcinogen levels in RBC (per hemoglobin) were significantly elevated in uremic patients in spite of the presence of severe anemia. These results suggest that patients with uremia are continuously exposed to higher levels of these carcinogens as compared with normal subjects. Our data also support the idea that these carcinogens in plasma and RBC are suitable for monitoring exposure levels in humans.

Adult↗
PubMed1992

[Therapeutic evaluation of imipenem/cilastatin sodium for bacterial infections in patients with hematological diseases].

1. To evaluate the efficacy and tolerance of imipenem/cilastatin sodium (IPM/CS) in severe infections associated with hematopoietic disorders, IPM/CS was administered to a total of 105 patients. 2. Out of 96 patients evaluable for efficacy, clinical responses were excellent in 23 patients, good in 30, fair in 15, poor in 19 and unknown in 9, and the overall response rate was 60.9%. 3. The most common underlying hematopoietic disease was acute non-lymphocytic leukemia and the most common infections were sepsis and suspected sepsis. 4. Daily dose, severity of infection and neutrophil count had effects on the clinical response. 5. The overall eradication rate of bacteria was 83.7%. 6. Side effects were observed in 10 patients (9.5%) and abnormal laboratory test results in 12 (11.4%). From the above findings, we have concluded that IPM/CS is very useful for the treatment of severe infections in compromised patients with hematopoietic diseases.

Adult↗
PubMed1991

Molecular events in the T cell-mediated suppression of the immune response.

To understand the mechanism of T cell-mediated suppression, we have established a number of suppressor T cell (Ts) clones of both CD4+ and CD8+ phenotypes that exert a definite suppressive effect on antigen-induced proliferative response of normal and cloned CD4+ helper T cells (Th). When an antigen-activated Ts clone was added to Th clones that were subsequently stimulated with antigen and APC, the increase of intracellular Ca2+ in the latter was greatly inhibited. The suppression was unidirectional where Ts suppressed Th but not vice versa. A Ts clone could not suppress other Ts clones. Exactly the same suppression of Ca2+ response could be induced by the treatment of T cells with an anti-I-J antibody. The anti-I-J suppressed the Ca2+ response of Th clones induced by antigen-pulsed APC and anti-TcR alpha beta antibody, whereas the responses to anti-CD3 and Con A were not inhibited. The difference in the effect of anti-TcR alpha beta and anti-CD3 suggests that the suppression is caused by a functional uncoupling of TcR alpha beta and CD3. The stimulation of Ts clones with anti-CD3, on the other hand, induced a unique suppressor factor that potently inhibits the antigen- and anti-TcR induced proliferation of CD4+ Th clones.

Animals↗
PubMed1991

Human herpesvirus-6 infection in bone marrow transplantation.

Twenty-five pediatric patients who received bone marrow transplantation (BMT) were studied prospectively to determine the relationship between BMT and human herpesvirus-6 (HHV-6) infection by the virus isolation from peripheral blood and/or bone marrow and by determining neutralizing antibodies to HHV-6 during the 2 months following BMT. All of the 25 donors and the recipients were immune to HHV-6 at the time of BMT and the virus was not isolated from them. HHV-6 was isolated from peripheral blood and/or bone marrow mononuclear cells in ten (40%) of the 25 recipients between day 14 and day 22 of BMT, but not from any other day. Two additional recipients showed a significant increase in the antibody titer. Thus, infection with HHV-6 was confirmed in 12 (48%) of the 25 recipients. Four of the 12 developed skin rashes; three of these four had a febrile episode when the virus was isolated, whereas none of the remaining 13 developed the skin rash. These results suggest a frequent infection with HHV-6 only a few weeks after BMT and a close association between the infection with the virus and the development of skin rashes.

Adolescent↗
PubMed1991

Differentiation of oka varicella vaccine strain from wild varicella-zoster virus strains isolated from vaccinees and household contact.

The Oka varicella vaccine strain can be differentiated from wild-type strains by its unique restriction endonuclease fingerprinting (REFP: HpaI-K and EcoRI-P) pattern of the gpV-coding region of the varicella-zoster virus (VZV) genome. VZV-DNAs from patients with complicated clinical courses related to vaccination were examined to determine whether they were vaccine-derived or wild-type. A virus was isolated from a one year-old boy with acute lymphocytic leukemia (ALL) who developed typical varicella 28 days after vaccination (case A). Another virus was isolated from a four-year-old boy without clinical symptoms following household contact with varicella patients at the age of two months, and he developed zoster 14 months after vaccination (case B). Also, two strains (OK1 and OK2) were isolated from household contacts (mother and sister) with a vaccine with ALL in Oklahoma who developed varicella 18 days after vaccination (case C). In case C, BgII-REFP did not determine conclusively whether the two strains (OK1 and OK2) were vaccine-derived or wild-type because the patterns obtained were different from both the Oka varicella vaccine strain and American wild-type strains [Gelb et al., Journal of Infectious Diseases, 155:633-640, 1987]. All VZV strains examined in the present study were identified as wild-type by our method using HpaI-K and EcoRI-P fragments as marker fragments. Thus it is becoming evident that REFP using HpaI and EcoRI endonucleases is a convenient and reliable means of distinguishing between the Oka vaccine virus strain and wild-type viruses isolated from individuals developing vesicular rashes shortly and long after varicella vaccination.

Biomarkers↗
PubMed1991

Surgical treatment of cavernous angioma involving the brainstem and review of the literature.

Five cases of symptomatic cavernous angioma involving the brainstem are reported. Magnetic resonance (MR) imaging is of greatest value in the diagnosis and for surgical indication. All cases were treated by radical extirpation. All of them improved postoperatively. The surgical indications for this lesion of the brainstem are briefly discussed with a review of the literature, including 28 previous cases, operated on directly.

Adolescent↗
PubMed1991

Low-dose aclarubicin in blastic transformation of essential thrombocythemia.

We attempted treatment with low-dose aclarubicin (ACR), a new anthracycline, in a 66-year-old man with blastic transformation of essential thrombocythemia (ET). Two courses of ACR (20 mg/day x 7 days) were given intravenously. He showed a good response to this therapy without severe side effects. He has since maintained a state of prolonged remission. These observations indicate that low-dose ACR may be beneficial for management of the blastic transformation of ET.

Aclarubicin↗
PubMed1991

Single photon emission computed tomography with Tc-99m-dimercaptosuccinic acid in patients with upper urinary tract infection and/or vesicoureteral reflux.

By means of Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy, an established method for assessing renal cortical damage, we evaluated the pick-up rate for renal defects (scars) by single photon computed tomography (SPECT) and planar images of 10 normal volunteers, and 58 patients (70 scintigrams) with upper urinary tract infections, most of whom had a history of vesicoureteral reflux (VUR). The positive study rate for renal defects depended on the severity of VUR. The overall positive rates for renal cortical defects obtained by DMSA SPECT imaging and DMSA planar imaging were 60% and 43%, respectively, and the difference between these was significant (p less than 0.005). The mean absolute individual renal uptake (/injected dose) at 2 hours post-injection was decreased in kidneys with defects detected by SPECT alone. The positive study rate for intravenous urography (IVU) depended on the grade of VUR and was 15% overall. DMSA SPECT imaging detects renal cortical defects at greater frequency than previously achieved.

Adolescent↗
PubMed1991

Effects of aprindine on monophasic action potentials.

Using a catheter electrode developed by the authors for recording monophasic action potentials (MAPs), the atrial and ventricular MAPs of seven mongrel dogs were simultaneously recorded. The results were used to evaluate the effect of the new antiarrhythmic drug aprindine on MAPs. An electrophysiologic study was also carried out to evaluate the effect of aprindine on the conduction system. Aprindine caused a significant increase in both the AH interval (at a basic cycle length of 400 ms) and the HV interval (at basic cycle lengths of 400 and 500 ms). The effective refractory period increased in both the right atrium and the right ventricle. Although an increase in MAP duration at repolarizations to 90% MAP (MAPD90) was not observed in the right atrium, a significant increase was noted in MAPD90 in the right ventricle. There were no significant changes in the ratio between the effective refractory period and MAPD90 of the right ventricle before and after administration of aprindine. This result suggests that increases in MAPD90 contribute to an increase in the effective refractory period of the right ventricle.

Action Potentials↗