Biomedical subjects

S Onoe

Publications and source records attributed to S Onoe.

At least 37 records · Page 2Linked to original sources

PubMed1992

Changes in glucose level affect rod function more than cone function in the isolated, perfused cat eye.

The glucose concentration (gl) in mammalian serum incorporates a normal range of variation of several millimoles. We studied the effects of such variations on light-evoked electrical signals in the in vitro arterially perfused cat eye, avoiding extraocular regulatory mechanisms that might confound data interpretation. Changes in gl from the nominal control value of 5 mmol/l were maintained for 5-40 min. Stimuli of near rod threshold intensity were presented in full dark adaptation, and stimuli of higher intensity were presented in the presence of a white background for cone responses. We recorded the dc-electroretinogram (ERG), the scotopic threshold response (STR), the optic nerve response (ONR), and the transretinal slow P-III and transepithelial retinal pigment epithelium c-wave from the subretinal space. The ocular standing potential changed by up to +/- 2 mV in parallel with an increase and decrease in gl, independent of the adaptation condition. Our results show that the rod-ERG, STR, and rod-driven optic nerve response (ONR) have a marked sensitivity to small changes in gl (+/- 1 to 3 mmol/l). The field potentials increased and decreased in parallel with changes in gl. The cone ERG and cone ONR, in contrast, failed to respond consistently to increases in gl and revealed decreases in amplitudes only with an extreme decrease in gl. Decrease in gl, down to 2 mmol/l and less, is known to induce drastic behavioral and electrophysiologic phenomena in the central nervous system. Our results imply that the "normal" glucose level, at least in the cat, could be marginal for rod-mediated retinal function. The results also suggest a marked difference in metabolic mechanisms for cone versus rod photoreceptors.

Animals↗

PubMed1992

[Changing glucose concentration affects rod-mediated response in the perfused cat eye].

The effects of changing glucose concentration on the ERG b-wave and optic nerve response (ONR) were studied in dark adapted, arterially perfused cat eyes. Changes in glucose concentration in the perfusate induced remarkable effects on both electrical responses. The ERG b-wave and ONR amplitudes were enhanced with increasing the glucose concentration above the standard level (5.5 mM), and were transiently decreased below the control after termination of the increase in glucose. Furthermore, a control perfusate with higher glucose concentrations (8-10 mM) was used, transient addition of glucose failed to elicit consistent increase in amplitudes of the b-wave and ONR. We conclude that the optimal supply of glucose to the mammalian retina is crucial for recording b-wave and ONR in-vitro under dark adaptation. A higher glucose level (8-10 mM) than 5.5 mM in the standard tissue culture medium is suggested for maintaining the retinal function in-vitro.

Action Potentials↗

PubMed1991

Purification of bicarbonate-sensitive sperm adenylylcyclase by 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid-affinity chromatography.

Anion transport inhibitors, such as SITS (4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid) and heparin, inhibit reversibly the bicarbonate-sensitive adenylylcyclase of porcine sperm plasma membrane. In the light of this, SITS- and heparin-affinity chromatographies were applied in order to purify sperm adenylylcyclase. SITS-Affi-Gel 102 binds proteins extracted from the porcine cauda epididymal sperm plasma membrane by Lubrol-PX, more selectively than heparin-agarose. However, recovery of adenylylcyclase activity is higher when heparin-agarose is used. The hormone-sensitive liver adenylylcyclase, which is less sensitive to bicarbonate than sperm enzyme, has less affinity for these affinity resins than sperm enzyme. Adenylylcyclase can be purified to apparent homogeneity on two-dimensional gel electrophoresis (isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis) from the Lubrol-PX extract of the purified sperm plasma membrane by using SITS-affinity chromatography at the first step of the purification followed by preparative isoelectric focusing and gel filtration. The molecular weight and pI of the purified enzyme are 46,300 and 6.9, respectively. The purified enzyme activity is highly dependent on Mn2+. Bicarbonate activates even the purified enzyme both by decreasing Km and by increasing Vmax.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗

PubMed1991

Water insoluble fraction of egg yolk maintains porcine sperm motility by activating adenylate cyclase.

The decrease in motility of porcine cauda epididymal sperm was less than that of caput epididymal sperm in the medium containing bicarbonate. This may be due to the difference of sensitivity of adenylate cyclase to bicarbonate between mature and immature sperm; activation of mature sperm enzyme by bicarbonate was higher than that of immature sperm. Nondialysable fraction of egg yolk prevented the decrease in motility of immature sperm in the presence of bicarbonate, but it was not effective for the motility of mature sperm under the same condition, because only bicarbonate is sufficient for the maintenance of its motility. In the absence of bicarbonate, both mature and immature sperm required egg yolk to maintain motility. The favorable effect of egg yolk on the motility is ascribed to the enhancement of intracellular cAMP level. Partial fractionation of egg yolk showed that water-insoluble lipoprotein fraction contains factor(s) which activates adenylate cyclase in sperm plasma membrane. This is the first report in which high molecular weight activator of the sperm enzyme was demonstrated.

Adenylyl Cyclases↗

PubMed1991

[The effect of glucose on rod function in the isolated, perfused cat eye].

Effects of changing glucose concentration on light-evoked, rod-matched electrophysiological responses were studied in isolated, arterially perfused cat eyes. 1. changes in glucose concentration in the perfusate induced remarkable effects in the electrical responses of retinal pigment epithelium neural retina, and optic nerve. 2. The ERG b-wave and the optic nerve response (ONR) were enhanced when glucose concentrations were increased above the standard level (5.5 mM), and were less than normal after termination of the increase in glucose, prior to recovery. 3. Decreasing glucose from the standard led to attenuation of b-wave and ONR. Both responses recovered completely upon returning to 5.5 mM glucose 4. When the control perfusate contained higher glucose concentrations (8-10 mM), additional glucose failed to elicit significant effects on the b-wave and on the ONR. 5. Increasing glucose induced a small transient decrease in standing potential, followed by a marked and maintained increase. Decreasing glucose induced changes of similar magnitude but opposite polarity. 6. Supply of glucose to mammalian retina in vitro is crucial for optimal sensitivity as shown in rod-matched signals from the perfused cat retina.

Animals↗

PubMed1991

Isolation of bovine coronavirus from feces and nasal swabs of calves with diarrhea.

Fecal and nasal samples were collected from 180 calves with diarrhea and 36 clinically normal co-habitants, and tested for virus using HRT-18 cell cultures derived from human rectal adenocarcinoma. A cytopathic virus was isolated from 5 fecal and 56 nasal samples obtained from diarrheic calves. All calves in which the virus was isolated from diarrheic feces were positive for virus isolation from nasal swabs. The virus was also isolated from the nasal swabs of 10 clinically normal calves that were co-habitants with diarrheic calves. Because they were morphologically similar to coronavirus, agglutinated mouse erythrocytes and serologically identical with the Nebraska calf diarrhea coronavirus, new isolates were identified as bovine coronavirus. The demonstration of viral antigens in nasal epithelial cells by a direct immunofluorescence was in close agreement with the virus isolation in HRT-18 cell cultures. This is the first report on the isolation of bovine coronavirus from newborn calves with diarrhea in Japan. The evidence that the virus was frequently isolated from nasal swabs is of great interest for understanding the pathogenesis of bovine coronavirus infection.

Adenocarcinoma↗

PubMed1990

Effects of a membrane-bound trypsin-like proteinase and seminal proteinase inhibitors on the bicarbonate-sensitive adenylate cyclase in porcine sperm plasma membranes.

Plasma membranes were purified from flagella of porcine cauda epididymal sperm and proteolytic regulation of bicarbonate-sensitive adenylate cyclase was studied. It was found that the epididymal sperm plasma membrane contained a trypsin-like proteinase which inactivated adenylate cyclase. Bicarbonate activates adenylate cyclase as reported previously, but, at the same time, the anions enhance the inactivation of the enzyme by the membrane-bound trypsin-like proteinase. This phenomenon is not due to the direct activation of the proteinase, but closely related to the activation of adenylate cyclase by bicarbonate. It was also found that seminal proteinase inhibitors blocked the inactivation of adenylate cyclase and maintained the bicarbonate activation of the enzyme at high level. Actually, bicarbonate keeps adenylate cyclase fully active in ejaculated sperm, because membrane-bound proteinase is completely inhibited by the seminal proteinase inhibitors. These results suggest that the interactions between membrane-bound proteinase and seminal proteinase inhibitor are involved in the regulation of the bicarbonate-sensitive adenylate cyclase system.

Adenylyl Cyclase Inhibitors↗

PubMed1990

[Effects of adenosine on the electrophysiology of the retina].

To the authors' knowledge, adenosine has not yet been shown to play any functional role in the mammalian retina, although it has been shown that it induces neuromodulation and an antiepileptogenic action of the purine in the brain. In order to test effects on retinal function, adenosine was administered intraarterially, in micromolar concentrations, to dark-adapted, isolated, perfused cat eyes. Light-evoked (rod-matched) electrical signals were recorded. Adenosine induced a marked increase in the amplitude of the ERG b-wave, a dose-dependent depression of the optic nerve response, and an increase in the flow rate of the perfusate - indicative of vasodilation. These data, together with autoradiographically demonstrated uptake of adenosine (2) are the first evidence that adenosine plays a functional role at several sites in the cat retina.

Adenosine↗

PubMed1989

Protection against bovine rotaviruses in newborn calves by continuous feeding of immune colostrum.

Three pregnant cows were inoculated intramuscularly with inactivated vaccine to bovine rotavirus (BRV) serotype 1 (BRV-1) and serotype 2 (BRV-2). Serum neutralizing antibody (NA) titers against both serotypes increased significantly after immunization. NA titers of colostrum obtained from immunized cows against BRV-1 and BRV-2 were 29286 and 38109, respectively, which were significantly higher than those from non-immunized control cows. Nine and 6 colostrum deprived calves were orally challenged with BRV-1 and BRV-2, respectively, and monitored for clinical manifestation and viral shedding. Five calves of them, 3 with BRV-1 and 2 with BRV-2, received 2 l of milk replacer supplemented with 10% immune colostrum 2 hr before challenge and twice daily for the first 5 days after challenge. Other 10 calves, 6 with BRV-1 and 4 with BRV-2, were fed only milk replacer as controls. All control calves developed severe diarrhea and shed a large amount of BRV in feces, beginning from 24 to 48 hr after challenge inoculation. On the contrary, all calves but one fed colostrum supplement remained clinically healthy after challenge, and BRV was not detected in their feces during feeding immune colostrum. The possibility that continuous feeding of immune colostrum is capable of preventing newborn calves from diarrhea associated with BRV and viral shedding was suggested.

Animals↗

PubMed1988

Electroretinogram c-wave and slow PIII of the rabbit: changes in peak time and amplitude under various stimulus durations.

Changes in peak time and amplitude of the direct current registered c-wave of the electroretinogram of the albino rabbit were investigated with various stimuli of duration ranging from 0.25 to 10 sec. The stimulus intensity was 500 lux at the surface of the cornea. Slow PIII was isolated by administrations of sodium iodate and sodium aspartate. The peak time of the c-wave was longer than that of the slow PIII in the range of stimulus duration less than 3.5 sec, but peak times were almost the same in the range above 3.5 sec. The amplitude of the c-wave at peak was larger than the corresponding amplitude of the slow PIII in the range less than 1 sec, but the slow PIII became larger than the c-wave at more than 1 sec. For stimuli less than 4 sec, the smaller the stimulus duration, the smaller was the negative slow PIII which affected the height of the c-wave. We conclude that in order to minimize the influence of the slow PIII on the c-wave, the duration of stimuli with intensity of 500 lux for recording the c-wave of the rabbit should be less than 4 sec.

Animals↗

PubMed1988

Incomplete congenital stationary night blindness: electroretinogram c-wave and electrooculogram light rise.

Three cases of congenital stationary night blindness are reported. In all patients a negative electroretinogram was recorded by single bright flash stimulation and changed to positive on sequential reduction of the stimulus intensities. Oscillatory potentials were recognized. Biphasic dark adaptation curves and moderate elevation of the relative logarithmic final threshold of dark adaptation were also found. Values of critical flicker fusion frequency were reduced to a mild or moderate extent. VEP latency was prolonged beyond the normal range in two cases. In all three the electroretinogram c-wave was extinguished despite a normal electrooculogram light-dark ratio. It is hypothesized that in congenital stationary night blindness some disorder may exist in the apical membrane of the retinal pigment epithelium but not in the basal membrane in view of dissociation between the c-wave response and the light rise in the electrooculogram.

Child↗

PubMed1988

Delayed bone development in epileptic children assessed by microdensitometer.

Bone development of metacarpal bones was assessed by microdensitometer analysis of hand X-rays from 101 epileptic outpatients. Most of the patients were treated with two or three anticonvulsant drugs; however, 27 patients were treated with only one. A significantly larger number of patients showed a delay in bone development of 2 or more years when compared with either handicapped or normal control children. In epileptic children, physical activity and the duration of anticonvulsant therapy were correlated with bone development. Patients with delayed bone development had reduced levels of serum 25-OH-D (p less than 0.005) and elevated levels of 1,25-(OH)2D (p less than 0.01). Microdensitometer analysis of metacarpal bone radiographs is useful for detecting mild impairment of bone in groups of epileptic children.

Adolescent↗

PubMed1986