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Biomedical subjects

Y Kitazawa

Publications and source records attributed to Y Kitazawa.

At least 109 records · Page 6Linked to original sources
PubMed1996

The effects of the beta-adrenergic-blocking agents, timolol and carteolol, on plasma lipids and lipoproteins in Japanese glaucoma patients.

PURPOSE: To determine whether two topical beta-blockers, timolol and carteolol, differently affect plasma lipids and lipoproteins in normolipidemic Japanese patients with glaucoma. PATIENTS AND METHODS: Thirty-three normolipidemic patients with primary open-angle glaucoma or ocular hypertension were randomly allocated to and completed 16 weeks of bilateral treatment with 0.5% timolol, 1.0% carteolol, or 2.0% carteolol twice daily in a three-center, prospective study. Patients using any drugs affecting plasma lipids or with a history of beta-blocker use of hyperlipoproteinemia were excluded. Fasting blood lipids and lipoproteins, including total cholesterol, high-density lipoprotein cholesterol, triglyceride, and apoproteins, were measured three times before therapy was initiated. These measurements were repeated every 4 weeks during the treatment period. RESULTS: The level of high-density lipoprotein cholesterol significantly decreased in the timolol treatment group but did not change in the carteolol treatment groups. The ratio of total cholesterol minus high-density lipoprotein cholesterol to high-density lipoprotein cholesterol increased in the timolol treatment group. CONCLUSIONS: Topical beta-blockers do affect plasma lipids in Japanese patients with glaucoma. The effects of timolol are greater than those of carteolol.

Adrenergic beta-Antagonists↗
PubMed1996

Relationship of nerve fiber layer defects and parafoveal visual field defects in glaucomatous eyes.

To evaluate the relationship between nerve fiber layer defects (NFLD) and parafoveal visual field defects in glaucomatous eyes, 23 eyes of 20 patients with open-angle glaucoma were studied by scanning laser ophthalmoscope (SLO). Only eyes in which the NFLD reached the temporal raphe in either hemisphere were used. We defined three topographic parameters of NFLD: 1) the angle (theta, degrees) of line 'A' from the optic disc center to the foveal pit, and line 'B' from the disc center to a point of the NFLD at the disc edge nearest line 'A'; 2) a horizontal distance (D1, mm) along the temporal raphe between the foveal pit and the internal edge of the NFLD; and 3) a vertical distance (D2, mm) between the foveal pit and either the superior or inferior internal edge of the NFLD. We defined the nearest defect location (in degrees from the fovea) as the nearest location with sensitivity loss of at least 6 dB (Humphrey visual field program 10-2). A highly significant correlation was found between each of the NFLD parameters and the nearest defect location (P < 0.001). The NFLD parameters we defined may be helpful for evaluating parafoveal visual function in glaucoma.

Adult↗
PubMed1995

An ultrasound biomicroscopic study of filtering blebs after mitomycin C trabeculectomy.

PURPOSES: To investigate the relation between filtering bleb function and ultrasound biomicroscopic images, and to establish a new classification system for filtering blebs according to these images. METHODS: After trabeculectomy with mitomycin C, the filtering blebs of 117 eyes from 117 patients with various types of glaucoma were examined using ultrasound biomicroscopy. Four parameters of the images-intrableb reflectivity, visibility of the route under the scleral flap, formation of a cavernous fluid-filled space, and bleb height-were correlated with the level of intraocular pressure (IOP). RESULTS: Reflectivity inside the bleb and visibility of a route under the scleral flap were highly associated with IOP control. Blebs were classified into four categories according to the four measured parameters: type L (low-reflective), type H (high-reflective), type E (encapsulated), and type F (flattened). Eyes with good IOP control had mainly type L blebs. Type E and type F blebs were seen mostly in eyes requiring additional medication. CONCLUSION: The structure inside a filtering bleb is visible by ultrasound biomicroscopy, and bleb function is significantly associated with its ultrasound biomicroscopic image in eyes trabeculectomized with adjunctive mitomycin C.

Adolescent↗
PubMed1995

Effect of occlusion on human skin.

In order to investigate the effect of occlusion on the skin, the flexor sides of both upper arms were covered with column-shaped with column-shaped closed chambers, 30 mm in outer diameter, 20 mm in inner diameter, and 5 mm in height, which were made of polyethylene foam. The tops of the chambers were sealed by plastic films with various levels of water vapor permeability to control moisture in each chamber. The raised chamber walls prevented direct contact between the skin and the plastic film. After 24 h of application, morphological changes of the skin surface were observed microscopically by the nitrocellulose-replica method. Although no visual alterations were found on all areas of occluded skin, microscopic evaluation showed that simple occlusion by films induced an increase in the number of deepened skin furrows on the skin surface. this increase was associated with lower water vapor permeability of the films, as well as with higher values of both temperature and humidity of the test day. Thus, since conditions which facilitate perspiration from the skin tend to cause skin irritation, prolonged exposure of the skin to sweat by simple occlusion may act as a primary skin irritant.

Adult↗
PubMed1995

Xanthine oxidase mediates paraquat-induced toxicity on cultured endothelial cell.

The role of xanthine oxidase in paraquat toxicity was investigated using cultured bovine pulmonary artery endothelial cells. Exposure to paraquat 0.1 mM was done for 24 hr with or without tungsten pretreatment and in the presence or absence of xanthine oxidase inhibitors. Exposure to paraquat significantly increased O2- production and relative xanthine oxidase activity (xanthine oxidase activity divided by total xanthine dehydrogenase plus xanthine oxidase) while depressing cell growth. In contrast, tungsten and allopurinol inhibited the increase of xanthine oxidase activity and decreased O2- release. Cell injury was assessed by leakage of lactate dehydrogenase and by fluorescein diacetate staining; it was found that oxidase inhibitors (both allopurinol and tungsten) reduced paraquat cytotoxicity. Thus the toxicity of paraquat was at least partly due to intracellular O2- production mediated by xanthine oxidase and the subsequent formation of other free radicals.

Allopurinol↗
PubMed1995

[A case of AIDS patient who was hard to diagnose from an initial symptom of interstitial pneumonitis].

A thirty-six year old male was admitted to the hospital because of fever and dyspnea. On the eighth day the patient turned out to be HIV positive. Although aggressive therapy was performed, the patient died of HIV related disease such as Pneumocystis carinii pneumonitis and CMV infection which led to multiple organ failure seventeen days after admission. We reported a case of AIDS patient who was hard to diagnose from an initial symptom of interstitial pneumonitis.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Intraocular pressure response to intravitreal injection of endothelin-1 and the mediatory role of ETA receptor, ETB receptor, and cyclooxygenase products in rabbits.

Endothelin-1 (ET-1) affects intraocular pressure (IOP) in rabbits. First, we studied IOP responses to the intravitreal injection of various doses of ET-1 ranging from 5 ng to 5 micrograms in unanesthetized rabbits, and observed a transient rise in IOP, from 0.5 to 2 h in duration, invariably followed by a prolonged IOP reduction, lasting for more than 72 h in rabbits treated with 0.5 microgram and 5 micrograms of ET-1. ET-1 (0.05 microgram and 0.15 microgram) resulted in a prolonged IOP reduction without an early IOP rise. Both IOP rise and reduction were significantly related to the dose of ET-1. A masked, randomized, study revealed that the intraperitoneal administration of indomethacin (50 mg/kg) prior to ET-1 injection significantly reduced the ocular hypertensive response, but not th ocular hypotensive response, to ET-1. The ETA receptor selective antagonist, 97-139 (155 micrograms) had no effect on IOP when used alone. However, when used in combination with 0.5 microgram of ET-1, 97-139 significantly inhibited both the IOP rise (0.5-2 h) and reduction (8-96 h) caused by ET-1. The ETB receptor selective agonist, sarafotoxin S6c (0.5 microgram), caused a sustained IOP reduction of 2 to 96 h in duration without the initial IOP rise. We also determined the concentration of prostaglandin (PG) E2 in the aqueous humor using radioimmunoassay techniques on samples obtained at 1 and 24 h after ET-1 injection, and examined the effects of pretreatment with indomethacin or 97-139 on PGE2 concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Hypoxia alters the energy metabolism and aggregation of washed human platelets.

Washed human platelets were incubated under hypoxic and normoxic conditions to investigate the influence of oxygen deprivation on energy metabolism and aggregation. The maximum aggregation rate, oxygen consumption, lactate production, and adenine nucleotide content were measured. Hypoxic incubation decreased the oxygen burst and maximum aggregation induced by thrombin, and accelerated anaerobic glycolysis. ATP and ADP levels were preserved, but the hypoxanthine level increased in the incubation medium and the platelet AMP level and adenylate energy charge decreased compared with normoxic incubation. Thus, anaerobic glycolysis failed to compensate for impaired oxidative phosphorylation during hypoxic incubation, suggesting that oxidative energy is essential for full platelet function.

Adenine Nucleotides↗
PubMed1995

[Observation of the chamber angle in primary angle-closure glaucoma with an ultrasound biomicroscope].

We observed the chamber angle in 47 eyes of 29 patients with primary angle-closure glaucoma using ultrasound biomicroscopy in dark and illuminated conditions. All observations were made before surgical intervention and without any drugs affecting pupillary reaction. Ultrasound biomicroscopy was repeated following laser iridotomy in 23 of the eyes. Out of 115 angle locations examined where no synechiae had been found by pressure gonioscopy, appositional angle closure was seen at 65 locations (57%) in 33 eyes (70%) in dark conditions. At 30 angle locations in 18 eyes, the appositional closure began in the vicinity of Schwalbe's line. After iridotomy, appositional closure was not observed even in dark conditions. Ultrasound biomicroscopy in dark conditions seems to be a promising procedure to visualize appositional angle closure in eyes with a narrow angle.

Aged↗
PubMed1995

The ocular hypotensive effect of the ETB receptor selective agonist, sarafotoxin S6c, in rabbits.

PURPOSE: Endothelin-1 (ET-1) is known to affect intraocular pressure (IOP) in rabbits, and the IOP response is likely to be mediated by the receptors ETA, ETB, or both. Sarafotoxin S6c (STX-S6c) is a selective agonist to ETB receptors. The authors attempted to clarify the role of ETB receptors in changes in IOP induced by ET-1 in rabbits using STX-S6c and to determine the relationship between the IOP response and various doses of STX-S6c. METHODS: Each concentration (10(-4) to 10(-7) M) of STX-S6c was injected intravitreally (20 microliters/eye) into one eye. The contralateral eye of each was used as a control. The IOP was measured periodically using a calibrated pneumatonometer. Indomethacin (50 mg kg-1) or vehicle (10 ml kg-1; 0.05 M phosphate buffer) was administered intraperitoneally twice, before and after intravitreal injection of STX-S6c (10(-5) M), and IOP was measured in the same protocol for 24 hours. RESULTS: In the STX-S6c (10(-4) and 10(-5) M) group, the IOP reduction was significant compared with the baseline (P < 0.05 to P < 0.01), starting from 6 and 4 hours and continuing until 192 and 72 hours after injection, respectively. A solution of 10(-6) M STX-S6c also resulted in significant reduction of IOP observed from 24 to 72 hours after injection (P < 0.05). The 10(-7) M solution of STX-S6c failed to affect IOP. The area under the curve of IOP response exhibited a significant correlation with the doses of STX-S6c (r = -0.856; P = 0.0001) in the treated eyes. Treatment with indomethacin failed to affect the IOP reduction caused by STX-S6c (10(-5) M). Ciliary injection and some dilatation of the iridial vessels were observed in eyes that received higher doses of STX-S6c. CONCLUSION: STX-S6c reduces the IOP in rabbits in a dose-dependent fashion, presumably mediated through the ETB receptors.

Amino Acid Sequence↗
PubMed1995

[The effect of an endothelin receptor antagonist, 97-139, on intraocular pressure in rabbits].

We studied intraocular pressure (IOP) response to an intravitreal injection of 10(-5)M (20 microliters) endothelin-1 (ET-1) in unanesthetized rabbits, and found a transient IOP rise followed by a prolonged IOP reduction. ET-1 (10(-6)M) caused a sustained IOP reduction without an initial IOP rise. The ETA receptor selective antagonist, 97-139 (10(-2)M, 20 microliters), had no effect when used alone; however, when used in combination with ET-1 (10(-5)M), 97-139 (10(-2)M) significantly blocked the ocular hypotensive response to ET-1. 97-139 (10(-3)M), when used with 10(-6)M ET-1, also suppressed the IOP reduction induced by ET-1. Aqueous prostaglandin (PG) E2, determined by radioimmunoassay, was significantly elevated following intravitreal injection of ET-1 (10(-5)M). Prior injection of 97-139 (10(-2)M) significantly suppressed the elevation of aqueous PGE2 concentration caused by ET-1 (10(-5)M). These results suggest that both the IOP response and the elevation of aqueous PGE2 following ET-1 injection are at least partially mediated by ETA receptor.

Animals↗
PubMed1995

[Hypotonous maculopathy following trabeculectomy with mitomycin C].

We retrospectively studied incidence, prognosis and predictive factors of hypotonous maculopathy following trabeculectomy with adjunctive mitomycin C. The subjects were 208 cases (208 eyes) with various types of glaucoma with clear media, who were followed up for at least three months postoperatively. The follow up periods ranged from 3 to 44 months with a mean of 21.1 months. The incidence of the maculopahy was 9.1% (19/208). The postoperative intraocular pressures (IOPs) varied between 1 and 6 mmHg in the presence of maculopathy. The maculopathy disappeared in 14 eyes (74%) spontaneously or following ocular hypertensive therapy including application of trichloracetic acid and subconjunctival injection of autologous blood. The final visual acuity deteriorated two lines or more in 8 eyes (42%). A discriminant analysis showed that age, history of intraocular surgery, preoperative maximum IOP, and mean deviation are the predictive factors for maculopathy. As compared with the hypotonous eyes without maculopathy, those with maculopathy tended to be younger and to have less severe visual field changes.

Adolescent↗
PubMed1995

[Relationship between the nerve fiber layer defect and parafoveal visual field defects in glaucomatous eyes].

We evaluated the nerve fiber layer defect (NFLD) in glaucomatous eyes imaged by a scanning laser ophthalmoscope (SLO, Rodenstock Gm BH, Munich, Germany) and its relationship to parafoveal visual field defects. Twenty-three eyes of 20 patients with open angle glaucoma were studied. Only those eyes were used in which NFLD reaching the temporal raphe of the nerve fiber layer was observed by the SLO in either the superior or the inferior hemisphere. We defined three topographic parameters of the NFLD: 1. the angle (0, degree) generated by a line A passing through the foveal pit and the disc center, and a line through the disc center to the point of the NFLD at the disc edge and closest to line A, 2. the horizontal distance (D1, mm) along the temporal raphe between the foveal pit and the point of the NFLD nearest to the foveal pit, and 3. the vertical distance (D2, mm) between the foveal pit and the point of NFLD nearest to the foveal pit. We also defined the nearest defect location (in degrees from the fovea) as the stimulus point with sensitivity loss greater than 6 dB in the Humphrey visual field (program central 10-2). A highly significant correlation was observed between each of the three NFLD parameters and the nearest defect location (p < 0.001). The NFLD parameters we have newly defined here may be helpful for evaluating parafoveal visual functional damages in open angle glaucoma.

Female↗
PubMed1995

The effects of endothelin-1 on intraocular pressure and pupillary diameter in rabbits.

Endothelin-1 (ET-1) reduced intraocular pressure (IOP) in animals when administered topically. The time-course of IOP changes induced by ET-1, however, has not been fully documented. We studied the IOP response to different doses of intravitreally injected ET-1 ranging from 10(-7) to 10(-4) M in rabbits. In each animal one eye received 20 muL of ET-1 solution and the contralateral eye received the same amount of vehicle in a randomized, masked fashion. IOP was measured by a pneumatonometer prior to and periodically for at least 72 hours after the intravitreal injection. ET-1 in 10(-4) and 10(-5) M concentration elicited an IOP response consisting of an initial rise of 1- to 2-hour duration, and a subsequent prolonged reduction lasting for more than 72 hours. The use of 3 x 10(-6) and 10(-6) M solutions resulted in a prolonged IOP reduction without an early IOP rise. No significant IOP change was induced by 10(-7) M solution or the vehicle. No change was observed in pupillary diameters after injection of ET-1 in any dose. The aqueous prostaglandin E2 concentration was significantly increased at both 1 and 24 hours after 10(-5) M ET-1 injection.

Animals↗
PubMed1995

The effects of ETB receptor-selective agonist on IOP and blood-aqueous barrier in rabbit eyes: role of cyclooxygenase products.

The authors have reported that ET-1 and ETB receptor agonist, sarafotoxin S6c (STX-S6c), caused prolonged intraocular pressure (IOP) reduction in rabbit eyes in a dose-dependent fashion when injected intravitreally. The purpose of this study was to determine the effects of STX-S6c on the blood-aqueous barrier and also the possible role of cyclooxygenase products in modulating IOP. Indomethacin, a cyclooxygenase inhibitor (50 mg/kg), or its placebo was administered intraperitoneally 1 hour before or 1 hour before and 4 hours after the intravitreal injection of 0.5 micrograms of STX-S6c into one eye in a group of albino rabbits. The fellow eye received the vehicle only. IOP was measured prior to and periodically up to 120 hours after the injection using a calibrated pneumatonometer. One hour and 24 hours following the injection of STX-S6c (0.5 micrograms) with or without indomethacin, approximately 100 microL of aqueous humor was withdrawn by paracentesis. Protein concentration was measured by Lowry's method and PGE2 concentration was determined by radioimmunoassay. Both single and double dosings of indomethacin failed to prevent the IOP reduction caused by STX-S6c. The eyes injected with STX-S6c exhibited a significant elevation of both PGE2 and protein concentration at both 1 and 24 hours after injection. Pretreatment with indomethacin could significantly suppress the PGE2 and protein content of aqueous humor at both 1 and 24 hours after injection. ETB receptor agonist, STX-S6c, appears to induce the IOP reduction without affecting the cyclooxygenase pathway or disrupting the blood-aqueous barrier.

Animals↗
PubMed1994

Pituitary adenoma and unexpected sudden infant death: a case report.

Pituitary adenomas can cause sudden death in adults, but they are quite rare during infancy. Herein we present an unusual case of sudden infant death associated with a pituitary adenoma. The clinical presentations were "quietness" complained of by the parents and probable gigantism with accelerated growth rate during the first 2 months of life. The female infants had been in good health until one day when, at the age of 3 months, she was found immobile in bed. Microscopic examination showed that the cells of the entire pituitary gland were replaced by bizarre undifferentiated tumor cells. There were no invasive lesions in the surrounding brain tissue. It was also found that the cortex of the adrenal glands was atrophic. No metastatic lesions were observed in any organ. While the mechanism leading our infant to death is both controversial and unknown, we speculated that insufficient secretion of steroid hormones might have caused cardiovascular collapse.

Adenoma↗