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Biomedical subjects

Y Asano

Publications and source records attributed to Y Asano.

At least 685 records · Page 38Linked to original sources
PubMed1985

Dopaminergic inhibition of the action of vasopressin on the cortical collecting tubule.

The dopaminergic inhibition of the hydrosmotic effect of vasopressin was studied by in vitro perfusion of the cortical collecting tubule isolated from the rabbit kidney. Arginine vasopressin (AVP) 100 microU/ml increased hydrosmotic water permeability (Pf, 10(-3) cm/s) by 11.4 +/- 1.59. Although dopamine 10(-5) M added alone to the bath did not affect Pf, the combined administration of 10(-5) M dopamine and 100 microU/ml AVP reduced the hydrosmotic effect of AVP to to 2.37 +/- 0.34. This inhibitory effect of dopamine was reversed by the simultaneous addition of 10(-5) M metoclopramide, a D2-antagonist. These observations suggest that dopaminergic receptors also exist in the cortical collecting tubule. The dopaminergic inhibition of the hydrosmotic action of AVP may be at least in part responsible for the diuretic action of dopamine.

Animals↗
PubMed1985

T cell regulation of B cell activation. Lyt-1+,2-T cells modify the MHC-restricted function of heterogeneous and cloned T suppressor cells.

Previous studies have shown the existence of both heterogeneous Lyt-1-,2+ suppressor (Ts) cells and cloned Lyt-1+,2- Ts cells which, despite the difference in their Lyt phenotypes, functioned in a similar antigen-specific and major histocompatibility complex (MHC)-restricted fashion to suppress the antibody responses generated by cloned helper T (Th) cells and hapten-primed B cells. Our studies were carried out to assess in further detail the genetically restricted cell interactions that mediate this immune response suppression. We show that the activation of both heterogeneous and cloned Ts cells is antigen-specific and MHC-restricted under our experimental conditions. After appropriate activation, the effector function of both cloned Lyt-1+,2-Ts cells and heterogeneous Lyt-1-,2+ Ts cells was also antigen-specific. In contrast, once activated, Ts cells suppressed the responses generated by cloned Th cells and hapten-primed B cells in an MHC-unrestricted fashion. We also showed, however, that a population of unprimed Lyt-1+,2-T cells was able to significantly alter the genetic restriction requirements for Ts cell function. The activity of this population was itself MHC-restricted, and was observed only when the unprimed Lyt-1+,2-T cells shared the MHC restriction specificity of the cloned Th cells functioning in a given response. When these requirements were satisfied, Lyt-1+,2- T cells significantly modified the suppression mediated by both heterogeneous and cloned Ts cells, resulting in suppression that was then MHC restricted in its effector function as well as in its activation requirements. Thus, our findings suggest that the observed MHC restriction in Ts function is the result of a complex interaction involving Ts cells, Th cells, and an additional population of MHC-restricted Lyt-1+,2- T cells. This newly characterized activity of Lyt-1+,2- T cells functionally resembles that of an MHC-restricted contrasuppressor population that selectively blocks a pathway of MHC-unrestricted Ts activity, while leaving intact susceptibility to MHC-restricted Ts effects.

Animals↗
PubMed1985

Localization of thyroxine 5'-monodeiodinase activity in the renal proximal tubules in rabbits and rats.

To determine the localization of T4 5'-monodeiodinase activity in rabbit and rat nephron segments, the formation of tri-iodothyronine (T3) from thyroxine (T4) was measured in kidney homogenate and in isolated nephron segments obtained by the microdissection method. In order of decreasing activity, homogenates of rabbit renal cortex, outer medulla and inner medulla were capable of converting T4 to T3. In the isolated nephron segments of the rabbit cortex, the activities were noted in both proximal convoluted and proximal straight tubules. On the other hand, the activities were not detected in segments including the cortical thick ascending limb of Henle's loop, the distal convoluted tubule, the connecting tubule, and the cortical collecting tubule. It is concluded that both the convoluted and the straight tubules are the sites of T3 production in the kidney.

Animals↗
PubMed1985

Viral replication and immunologic responses in children naturally infected with varicella-zoster virus and in varicella vaccine recipients.

Replication of varicella-zoster virus (VZV) and immunologic responses to VZV were examined by a sensitive culture technique for viral isolation and standard immunologic assays in children after close exposure to wild-type VZV or after inoculation with strain Oka varicella vaccine. Naturally infected children who developed clinical varicella had viremia between five days before and one day after clinical onset of disease, with the highest isolation rate one and two days before onset, and seroconversion followed two days later. Virus was not isolated from blood 12 and 13 days after contact in subclinically infected children. In the vaccine recipients a positive skin test reaction to VZV was observed as early as four to five days after immunization, and antibody appeared later. Virus was not isolated from blood and throat of the vaccinees from three to 14 days after immunization.

Antibodies, Viral↗
PubMed1985

On some properties of 222Rn short-lived decay products in air.

Simultaneous measurements were made of such properties as the fraction of charged and uncharged atoms, the balance of radioactive equilibrium between 222Rn and its daughters, and the concentration of aerosol particles and their mean radii in tunnel air. It became clear that the behavior of 222Rn decay products in tunnel air could be expressed well by equations based on a simple model, taking the following into account: the attachment of free atoms to aerosol particles, the deposition of radioactive particles on the tunnel wall, emission of alpha recoils from aerosol particles and the surface of the tunnel wall, and radioactive decay. In addition, the effective attachment coefficient of an observed RaA-atom was found to agree well with that calculated. The results obtained should facilitate in the future estimation of the relation between 222Rn daughters and the lung dose to the population.

Aerosols↗
PubMed1985

Hypergastrinemia and achlorhydria in chronic renal failure.

In 68 patients with chronic renal failure (CRF), 15 patients with duodenal ulcer and 15 normal subjects, basal plasma gastrin levels and basal and stimulated gastric acid secretion were measured. Two antisera were used: antiserum R2702 with specificity for human G34 and its N-terminal fragments [G34] and antiserum 2604 with specificity for the four main components of gastrin (total gastrin). Basal gastrin concentrations of both total gastrin and G34-like immunoreactivity (G34LI) were significantly higher in the CRF patients than in the other two groups, irrespective of dialysis. Total gastrin levels were not correlated with serum creatinine levels. Total gastrin levels were significantly decreased during hemodialysis, but G34LI levels showed no significant change. A small amount of total gastrin was detected in the dialysate by antiserum 2604. As to the postprandial gastrin release, in the first 30 min, the pattern of response in the patients with CRF was similar to that of the normal subjects, but the peak value was attained later, and the response was more rather prolonged. Gastric analysis showed a low basal acid out put and impaired acid secretion in response to secretagogue. It is concluded that (1) one of the predominant circulating forms of gastrin in CRF is G34LI, and (2) the hypergastrinemia in the CRF patients is probably due to reduced removal of gastrin by kidneys, increased gastrin production by impairment of the negative acid feedback mechanism induced by parietal cell dysfunction or reduced parietal cell sensitivity to gastrin by atrophic gastritis.

Achlorhydria↗
PubMed1985

Human alpha 1-microglobulin and its relationship to renal function.

To evaluate the clinical usefulness in terms of estimation for glomerular filtration rate (GFR), we determined the levels of alpha 1-microglobulin (alpha 1m) in the serum and urine of patients with various renal diseases and compared with those of beta 2-microglobulin (beta 2m) and creatinine. Serum and urinary alpha 1m levels were measured by using single-radial immunodiffusion method. 24-hour creatinine clearance (Ccr) was used as a indicator of GFR. There was a significant positive correlation between serum alpha 1m and creatinine levels (r = 0.75, p less than 0.001). Serum alpha 1m, beta 2m and creatinine inversely correlated and logarithmically correlated to Ccr as shown in the following equations: log alpha 1m = 2.30 - 0.42 X log Ccr (r = -0.74); log beta 2m = 2.06 - 0.91 X log Ccr (r = -0.92); log creatinine = 1.57 - 0.78 X log Ccr (r = -0.94). Both correlation coefficient and regression coefficient for alpha 1m were rather poor compared to those for beta 2m and creatinine. However, alpha 1m levels started to increase over normal range when Ccr fell below 80 liters/day, while beta 2m and creatinine remained within normal ranges. The daily urinary excretion of alpha 1m was increased in the patients whose Ccr was within normal limits compared to that of healthy control subjects (15.2 +/- 3.2 mg/day, n = 19, vs. 5.7 +/- 0.7, n = 7, p less than 0.001). Fractional clearance of alpha 1m increased proportionally to the decrease of Ccr. These data suggest that combined measurements of alpha 1m in the serum and urine seem to be useful to estimate GFR, especially to detect the mild reduction of CFR.

Adolescent↗
PubMed1985

Varicella vaccine: case studies.

A live varicella vaccine (Oka strain) has been developed. Clinical trials in normal and high-risk children have been carried out successfully in Japan, the USA and Europe, leading to recent licensing of this vaccine in several countries. Characterization of the vaccine and the results of clinical trials are reviewed in this article.

Animals↗
PubMed1985

Long-term protective immunity of recipients of the OKA strain of live varicella vaccine.

In spite of close contacts with patients who had varicella, 101 of 106 (95%) healthy and sick children (142 of 147 (97%) exposures of these children) who had received the OKA strain of live varicella vaccine 7 to 10 years earlier were protected against the disease completely. Among them, 37 of 38 (97%) vaccine recipients who received immunologic testing had varicella-zoster virus (VZV) antibodies tested by fluorescent antibody to membrane antigen method with a geometric mean titer of 1:9.3, and 37 of the 38 (97%) showed positive skin reaction to varicella-zoster virus antigen with erythema (mean diameter 13.4 mm). These findings were compared with those for 29 children who had contracted typical varicella 7 to 10 years earlier, whose seropositive rate was 100% with a geometric mean titer of 1:10.5, and 97% of whom (28/29) had positive skin reaction with mean diameter of 12.9 mm. These results indicate that the vaccine-induced protective immunity persists for approximately one decade and is almost equal to the long-term immunity following natural infection.

Adolescent↗
PubMed1985

Attenuation and laboratory markers of the Oka-strain varicella-zoster virus.

A live varicella vaccine was developed by serial passages of the Oka-strain varicella-zoster virus (VZV), isolated in our laboratory, in human embryonic lung cells and guinea-pig embryonic fibroblasts (GPEF). It is slightly temperature sensitive at 39 degrees C and shows a higher ratio of infectivity in GPEF to that in human embryonic fibroblasts (HuEF) than wild-type strains, indicating that it is a variant in thermosensitivity and host dependency. A DNA digest with the HpaI enzyme of the Oka strain contained a unique fragment, denoted K. Clinical studies with VZV isolated from vaccinees indicated that the GPEF/HuEF ratio of infectivity and the profiles of HpaI DNA digests are useful tests to differentiate the vaccine from wild-type strains. Prompt vaccination of household contacts proved effective in preventing spread of clinical varicella and seemed to be related to the early appearance (4-7 days after vaccination) of cell-mediated immunity in vaccinees, assessed by the VZV skin test. VZV could be isolated from mononuclear blood cells of varicella patients shortly before or after appearance of rashes, whereas no virus could be detected in 27 vaccinees 4-14 days after vaccination, suggesting that replication of the vaccine virus in susceptible organs and blood cells in humans is far less than that of wild-type viruses, but sufficient to induce VZV immunity. This difference seems to be related to the attenuated nature of the vaccine strain.

Animals↗
PubMed1985

Clinical experience with Oka live varicella vaccine in Japan.

A live varicella vaccine (Oka strain) has been developed and used since 1974 in normal and diseased children, particularly those at high risk. Children with acute leukaemia were usually vaccinated while in remission when showing a normal cell-mediated immunity as assessed with phytohaemagglutinin (PHA) or other reagents, and during suspension of all anticancer therapy, except 6-mercaptopurine from 1 week before to 1 week after vaccination. While clinical reactions were observed in only 40 out of 263 (15.2%) of these patients, they were noted in 30 out of 72 (41.7%) children immunized without suspension of chemotherapy. Symptoms were mostly mild; only a few cases of the latter group with T-cell leukaemia or malignant lymphoma developed severe symptoms. An immune response was observed in most vaccinees, but some (11%) developed clinical symptoms after exposure to natural varicella due to immunodepression caused by continuing anticancer chemotherapy. In these cases, revaccination seems advisable. The incidence and severity of zoster in vaccinated acute leukaemic children were less than in those with natural infection. Satisfactory immune responses with few concomitant clinical reactions were observed in approximately 1,500 vaccinees having nonmalignant diseases and in about 4,000 normal children. A 7-10-year follow-up study revealed that the vaccine had conferred solid immunity on the children. These results indicate that live varicella vaccine of the Oka strain is useful in preventing varicella in high-risk as well as in normal children.

Acute Disease↗
PubMed1985

Laser trabeculoplasty and cataract surgery.

We have compared long-term intraocular pressure control in patients with open angle glaucoma, cupping and atrophy of the optic nerve head and visual field loss as well as cataract after: trabeculectomy posterior to the scleral spur and cataract extraction without implantation in 108 patients. guarded posterior lip sclerectomy, cataract extraction and Mark VIII or Mark IX anterior chamber implantation in 28 patients. argon laser trabeculoplasty followed by lens extraction and implantation in 27 patients. Approximately 75 per cent of patients achieve intraocular pressures of 18 mm Hg or less without medication after (a), and approximately 40 per cent of patients achieve similar control without medication after (b). Approximately 25 per cent of these glaucoma patients have intraocular pressure levels of less than or equal to 18 mm Hg on topical medication three months after ALT, and none achieve this control without medication. Cataract surgery with anterior or posterior chamber implantation caused loss of topical control in four of the seven patients benefiting from ALT. These data imply that combined surgery with or without implantation produces better and more significant intraocular pressure control than the presently utilized techniques of ALT subsequently followed by lens extraction and implantation.

Anterior Chamber↗
PubMed1985

Trabeculectomy, cataract extraction and intra-ocular lens implantation.

Seventeen cases of open-angle glaucoma requiring cataract extraction underwent intracapsular cataract extraction, trabeculectomy posterior to the scleral spur, and MK9 intraocular lens insertion. Approximately 50 per cent of the patients achieved intraocular pressures of 18 mm Hg or less without medication two years later. Though implantation reduces the surgical success of the combined operation, it is safe, easy to perform and does not worsen pre-operative levels of intraocular pressure and/or control.

Cataract Extraction↗