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Biomedical subjects

H Sakaue

Publications and source records attributed to H Sakaue.

At least 37 records · Page 2Linked to original sources
PubMed1994

Electroretinogram b/a wave ratio improvement in central retinal vein obstruction.

The electroretinogram (ERG), especially the b/a wave ratio, is considered a good indicator of retinal ischaemia in central retinal vein obstruction (CRVO). Seven CRVO patients who showed b/a wave ratio improvement from < 1.0 [negative type (-) ERG] to > or = 1.0 and one from 1.07 to 1.53 were studied. Three mechanisms of change were observed: firstly, the b-wave amplitude increased without an a-wave amplitude decrease (group A, n = 2); secondly, the b-wave amplitude increased with an a-wave amplitude decrease (group B, n = 4); and, thirdly, both decreased, but the a-wave amplitude decreased more markedly (group C, n = 2). In group A, the visual acuities improved markedly. In group B, the visual acuities improved in two cases in which the b-wave amplitude reached the normal range; the visual acuities did not improve in two cases in which the b-wave amplitude did not reach the normal range. In group C, the visual acuities remained poor. The negative (-) ERG or significantly reduced b/a wave ratio is associated with ischaemic CRVO and did not occur because of the filtering effect of the haemorrhage, which may reduce the stimulus light for the ERG. Improvement of the reduced b/a wave ratio with an increased b-wave amplitude was accompanied by improvements in fundus appearance and visual acuity in CRVO. The results suggest that the retinal ischaemia in CRVO, as revealed by the ERG and fluorescein angiogram, may be reversible in some cases.

Adult↗
PubMed1994

[Gastroduodenal lesions in patients with liver cirrhosis--pathogenesis and management].

Gastroduodenal lesions are a common complication in patients with liver cirrhosis. The etiology of this problem has been investigated from the standpoint of both mucosal protective factors and aggressive factors. Among the various mucosal protective factors, much emphasis has been placed on the disturbance of microcirculation in the gastric mucosa as a result of stasis in the portal vein. Duodenogastric reflux may be involved in the etiology of the gastric mucosal changes. And, Phospholipids levels in the gastric mucosa were reduced in cirrhosis. Regarding aggressive factors, there have been many reports of diminished secretion of gastric acid. But, patients with ulcer had a tendency to be higher gastric acidity than those without ulcer. Drugs increased mucosal defense might be effective in healing gastroduodenal lesions in cirrhosis. Despite the observation that acid secretion decreased in cirrhosis, inhibition of acid secretion induces ulcer healing. In cirrhosis, a high incidence of gastric cancer was reported, so that patients should be undergo periodic screening with endoscopy.

Animals↗
PubMed1994

[Manometric study of the biliary sphincter zone: a comparison between the length of phasic activity and the narrow distal segment].

Motor activity of the sphincter of Oddi has been evaluated in 26 patients who underwent ERCP examination. Manometric recordings from the common bile duct and the sphincter of Oddi were performed with a single end-lumen perfused catheter. The number of successive 3 mm spaced black marks, observed during the pull-through from the first appearance of the proximal sphincter activity to that of duodenal pressure, was used to measure the length of the sphincter zone. In 14 of 26 patients, the length of phasic activity zone of the sphincter of Oddi was 9 mm. However, the narrow distal segment of the common bile duct was 15.1 +/- 3.6 mm in length. In same patients, the length of phasic activity zone was shorter than the anatomical one. The mean sphincter of Oddi pressure (SOP) at the distance of 6 mm from the papillary pore (77.8 +/- 22.1 mmHg) was greater than that of 9 mm (58.4 +/- 27.0 mmHg) and 12 mm (51.0 +/- 16.9 mmHg). These results suggest that the location of the orifice of catheter should be taken into consideration when comparing the SOP.

Adult↗
PubMed1993

A 3-year follow-up study of ocular hypertension by pattern electroretinogram.

A 3-year following-up study of the pattern electroretinogram (PERG) was performed in 15 eyes of 8 ocular hypertensive (OHT) patients. At first PERG recording, the amplitude of the first positive wave P1 was statistically significantly reduced in the OHT patients compared with age-matched controls (p < 0.05). There was no difference in the amplitude of the second negative wave N2 (p > 0.05). At 40 months, the amplitude of both P1 and N2 decreased and the latency of P1 was elongated. Among the changes, the decrease in N2 amplitude was the most drastic (p = 0.0001 compared with the control, p < 0.05, compared with the first recording). Glaucomatous visual field defects developed 5 years after the first PERG recording and 2 years after the reduction in N2 amplitude in 1 patient. Decreased N2 amplitude of the PERG may be an important warning sign predicting the development of glaucoma in OHT patients.

Adult↗
PubMed1992

[Effects of endothelin on retinal blood vessels].

Endothelins (ETs), which are one of the most potent vasoconstrictors, were discovered in 1988. ETs are involved in the regulation of vascular smooth muscle and are thought to function like a local hormone. In this study, we measured changes in the caliber of retinal blood vessels caused by the intravitreal injection of ET 1 in rabbits, using fundus photography. The retinal artery showed an immediate vasoconstriction after the injection (0.1 ml) of ET 1 at 10(-6)M. However, ET 1 in lower concentrations (10(-7)M and 10(-8)M) caused vasodilations initially and subsequently vasoconstrictions. A dose-response relation was found. The blood vessel caliber reduced maximumly to 53% the value before injection. The vasoconstriction due to ET 1 may induce retinal ischemia and hypoxia. We speculate that ET 1 may be involved in the regulation of retinal blood vessels.

Animals↗
PubMed1991

Retinal function in birdshot retinochoroidopathy.

The electroretinograms (ERGs) of 15 patients with birdshot retinochoroidopathy varied from super-normal to non-recordable, depending upon the severity and the stage of the disease. The abnormal ERGs were characterized by a disproportionate decrease of the b-wave amplitude compared with the a-wave amplitude, demonstrating the negative (-) type response. This distinct ERG pattern has not been observed in any other type of uveitis or chorioretinitis, and appears specific to birdshot retinochoroidopathy. ERG findings indicate that in birdshot retinochoroidopathy the neural layers of the retina are more diffusely and severely involved than the receptor-retinal pigment epithelium-choroid complex. In the most advanced stage, the patients becomes night blind with a non-recordable ERG, a situation that is essentially the same as retinitis pigmentosa, except that pigmentation is conspicuously absent in the fundus.

Adult↗
PubMed1990

Simultaneous pattern reversal ERG and VER recordings. Effect of stimulus field and central scotoma.

The effects of the sizes of the stimulus field and of an artificially created central scotoma on simultaneously recorded pattern-reversal electroretinogram (P-ERG) and pattern-reversal visual-evoked response (P-VER) were investigated. With an increase in the stimulus field from 4 degrees X 4 degrees to 12 degrees X 12 degrees, the amplitude of the P-ERG increased steadily. The amplitude of the P-VER also showed an increase up to a stimulus field of 6 degrees X 6 degrees or 8 degrees X 8 degrees, but showed no increase with further expansion of the stimulus field. A central scotoma, created by placing a square of black paper at the center of the 12 degrees X 12 degrees stimulus field, was increased from 4 degrees X 4 degrees to 10 degrees X 10 degrees by 2-degree increments. Amplitudes of both the P-ERG and the P-VER decreased with increasing central scotoma size. The P-VER decreased significantly with a 4 degrees X 4 degrees central scotoma. Although both the P-ERG and the P-VER were influenced by the overall stimulus field and the central scotoma, there was a distinct difference in their behavior. The P-VER showed saturation above a certain stimulus field size and, with a central scotoma of 4 degrees X 4 degrees, much more reduction than the P-ERG, suggesting that the P-VER depends more on the macular area than does the P-ERG. The P-ERG also exhibited a substantial macular dependency, which, however, was not as great as that of the P-VER. The greater macular dependency of the P-VER compared to the P-ERG, as observed in our study, reflects the larger anatomic representation of the macula at the higher visual level.

Adult↗
PubMed1990

Effect of optical defocus on the steady state pattern reversal visual-evoked response.

The effects of optical defocusing with convex lenses on the amplitudes of pattern reversal visual-evoked response (PVER) were investigated. With the large check size and high-contrast pattern, PVER amplitudes showed a linear decrease in response to initial defocusing up to +5 to +6 dptr. As the degree of defocus increased, the PVER amplitude, though irregular, continued to show reliable, definite responses up to +25 dptr. With the intermediate check size and pattern contrast, PVER amplitudes displayed a linear decrease, but unlike the large-check/high-contrast condition, diminished to noise level after a defocus of greater than +4 to +5 dptr. From these results, we speculate that two phases in this function curve derive from the large-check/high-contrast condition: first, the contrast- or contour-dependent phase, and, second, the luminosity/movement-dependent phase.

Adult↗
PubMed1989

Electroretinographic findings in fellow eyes of patients with central retinal vein occlusion.

In the study of 50 patients with unilateral central retinal vein occlusion, abnormal electroretinograms were observed in the fellow eyes of 18 patients (36%). The abnormal electroretinograms were supernormal in 15 patients (30%) and negative (+) in the fellow eyes of 3 patients (6%). The amplitudes of a and b waves were significantly greater in the fellow eye than those in normal controls. During a 1- to 9-year follow-up, central retinal vein occlusion developed in three fellow eyes (6%). The abnormal electroretinograms in the fellow eyes reflected such factors as circulatory disturbance of the retina that might have led to central retinal vein occlusion in the affected eye.

Adult↗
PubMed1989

Recording pattern reversal visual evoked response with the scanning laser ophthalmoscope.

We recorded visual evoked responses (VERs) to alternating, checkerboard pattern stimuli using the scanning laser ophthalmoscope (SLO). Retinal position and focus of checkerboard stimuli were monitored on the SLO video monitor throughout testing. Checkerboard size, check size, and retinal positions were varied. Consistent with other, well-established pattern reversal techniques, the SLO method produced: 1) reliable VERs with amplitudes of 2 to 10 microvolts, 2) maximum amplitudes at an intermediate check size for a fixed overall pattern size, and 3) variations in VER amplitude depending on stimulus retinal position relative to the fovea. Hence, the SLO-VER technique would be useful for clinical VER measurements when precise retinal stimulus position and focus are desired.

Computer Systems↗
PubMed1989

Measurement of vitreous oxygen tension in human eyes.

The vitreous oxygen tension in the human vitreous body was measured using a polarographic oxygen electrode during vitreous surgery. To the best of the authors' knowledge, this is the first time these measurements have been taken in the human eye. The vitreous oxygen tensions in the anterior peripheral vitreous body, central vitreous body, and posterior vitreous body were 16.7 +/- 3.7 mmHg (mean +/- SD, n = 9), 15.9 +/- 2.8 mmHg and 19.9 +/- 4.8 mmHg, respectively. The preretinal oxygen tensions over the detached retina and detached macula were 30.0 +/- 4.8 mmHg (n = 5) and 15.3 +/- 2.1 mmHg (n = 3), respectively, with the latter significantly lower than the former (P less than 0.01). In one case, after inhalation of 100% oxygen the oxygen tension over the retinal scar resulting from cryoretinopexy in a previous retinal detachment surgery increased remarkably to 160 mmHg.

Diabetic Retinopathy↗
PubMed1989

Comparative study of vitreous oxygen tension in human and rabbit eyes.

For the first time, vitreous oxygen tension in the human vitreous body was measured using a polarographic oxygen electrode during vitreous surgery. The same method was used in a rabbit experimental model. In the human eye, the mean oxygen tensions of the anterior peripheral vitreous body, central vitreous body and posterior vitreous body were 16.7 +/- 3.7 mm Hg (mean +/- 1 SD), 15.9 +/- 2.8 mmHg and 19.9 +/- 4.8 mm Hg, respectively, while the preretinal oxygen tension of the detached retina was 30.0 +/- 4.8 mm Hg. In the rabbit eye, the mean oxygen tensions of the anterior peripheral vitreous body, central vitreous body and posterior vitreous body were 13.9 +/- 4.3 mm Hg, 16.0 +/- 3.5 mm Hg and 22.5 +/- 2.1 mm Hg, respectively. The preretinal oxygen tension of the attached retina in the rabbit eye was 39.5 +/- 3.4 mm Hg, while that of the detached retina decreased to 4.3 mm Hg. When comparing human with rabbit eyes, it appears that the vitreous oxygen tensions are similar, except over the detached retina, even though the ocular circulation differs. We believe that human retinal vasculature plays an important role in perfusing the detached retina with relatively high levels of oxygen.

Animals↗
PubMed1988

The developmental changes of ERGs on spontaneous retinal degeneration of Celestial goldfish.

The Celestial goldfish, which belongs to the family of telescope-eye goldfish, displays unique spontaneous retinal degeneration associated with developmental anterodorsal protrusion of the eyeball. We observed concurrent changes in the electroretinogram. At the age of 75 days, the retinal layer was developed fully and the electroretinogram exhibited b-wave dominance similar to that of adult common goldfish. At the age of 105 days, when the eyeball began to protrude laterally, the b-wave amplitude decreased to 52% of its earlier developmental stage, with a prolonged peak time. Histologic change was observed in the retinal pigment epithelium and photoreceptor layers. At the age of 135 days, when the eyeball protruded further anterodorsally, the histologic changes extended to all retinal layers and the ERG b-wave was extinguished. Electrophysiologic and histologic changes in the Celestial goldfish eye were found to be proportional to the grade of eye protrusion. Since similar goldfish do not show these changes, however, the Celestial goldfish may be a new model of hereditary retinal degeneration.

Animals↗
PubMed1987

Effects of prolonged oral cimetidine, ranitidine, and famotidine therapy on antipyrine elimination.

The effects of three histamine H2-receptor antagonists on the antipyrine metabolizing capacity of the liver were studied in 32 patients with gastrointestinal disorders and in three healthy volunteers. The drugs studied were 800 mg and 400 mg of cimetidine, 300 mg of ranitidine, and 40 mg of famotidine daily. Only cimetidine at 800 mg/day inhibited hepatic antipyrine metabolism, and the inhibitory effects disappeared rapidly with no accumulation.

Administration, Oral↗
PubMed1987

Electrophysiological studies of spontaneous retinal degeneration in celestial goldfish (chotengan).

Spontaneous retinal degeneration of Celestial goldfish was studied histologically and electrophysiologically. Retinal degeneration was divided into three stages. Until the age of 75 days (Stage 0) the retina showed normal histological development and the electroretinograms (ERGs) exhibited dominant b-waves similar to those of adult common goldfish. By the age of 105 days (Stage 1), when the eyeballs began to protrude laterally, histological changes were first observed in the retinal pigment epithelium and photoreceptor layer. The b-wave amplitude decreased to 52% of that of Stage 0 with a prolongation of the peak latency. By the age of 135 days (Stage 2), when eyeballs protruded further anterodorsally, the retinal degeneration extended to the entire retinal layers and no b-waves were detected. The deterioration of the b-wave amplitude was closely correlated to the histological findings of retinal degeneration. The Celestial goldfish is considered to be a new model of hereditary retinal degeneration.

Animals↗
PubMed1983

A case report of abetalipoproteinemia (Bassen-Kornzweig syndrome)--the first case in Japan.

The clinical and pathophysiological features of a case of abetalipoproteinemia in a 34-year-old patient are described. This patient is the first case reported in Japan. The patient was diagnosed as abetalipoproteinemia by confirming the Apo-B deficiency in the patient's serum and the slightly high cholesterol level in his mother's and borderline normal level in his father's. The patient had remarkably low lipid levels, acanthocytosis, and lipid malabsorption. An unusual feature of this case was that the patient had no neuromuscular or ocular manifestations. This was possibly related to his normal plasma vitamin A and E levels.

Abetalipoproteinemia↗