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Biomedical subjects

M Sawa

Publications and source records attributed to M Sawa.

At least 109 records · Page 6Linked to original sources
PubMed1991

[The present status and the future of artificial liver support].

Orthotopic liver transplantation, started by Dr. Starzl in 1963, has already become an well established therapeutic method for the treatment of fulminant hepatic failure especially since the introduction of Cyclosporin A. On the other hand, hemoadsorption using charcoal, PAN membrane hemodialysis and plasma exchange were actively applied for clinical cases with fulminant hepatic failure between 1960 and 1970, but the survival rates were not so improved as expected due to the lack of metabolic functions. Hybrid artificial liver has been therefore investigated experimentally to support metabolic functions by using biomaterials such as isolated hepatocytes. Today many efforts are being made to keep hepatocytes highly viable for a long period of time by calcium alginate entrapment, spheroid formation, or by using biomatrix, some polymers, and microcarriers, etc. In the future, xeno-hepatocytes or so-called super cell will be realized and applied for artificial liver support with the development of gene operation techniques.

Artificial Organs↗
PubMed1990

New wound-healing model using cultured corneal endothelial cells. 1. Quantitative study of healing process.

A new in vitro model to evaluate the corneal endothelial wound-healing process was developed. Confluent monolayer cell sheets of either rabbit or bovine corneal endothelial cells were cultured on cover slips, the surface of which had been precoated with hydroxyethyl methacrylate (HEMA) except for the 8 mm-diameter area for cell culture. Wounds were made by scraping off cells in the center of the cell sheets using a rotating silicone tip. The areas of these wounds were measured by a method of computed planimetry. The average wound area was 3.00 +/- 0.21 mm2 in rabbit cell cultures and 3.18 +/- 0.28 mm2 in bovine. The healing process after the wounding was observed using an inverted phase contrast microscope and wound-healing rates (healed area per hour) were calculated. Wounded areas were recovered by 60 hours in rabbit experiments, and by 84 hours in bovine experiments. Wound-healing rates were different among the observation periods and showed differences between the two species. The healing rates in the rabbit were higher than those in the bovine in the early phase. This in vitro model can be used for quantitative evaluation of the wound-healing process of the corneal endothelium.

Animals↗
PubMed1990

New wound-healing model using cultured bovine corneal endothelial cells. 2. Role of migration and mitosis studied by immunohistochemistry.

The roles of migration and mitosis in the in vitro corneal endothelial wound-healing process were studied using an immunohistochemical method. The in vitro wound-healing model was a cultured cell sheet prepared using bovine corneal endothelium, and the wound was made at the center of the cell sheet using a rotating silicon tip. Following the wounding, specimens were incubated with bromodeoxyuridine (BrdU) for 12 hours. After the fixation with 10% phosphate-buffered formalin, the cells incorporating BrdU were stained by the avidin biotin peroxidase complex method. In 12 hours after the wounding, no stained cells were observed. In 24 hours, cell migration had started and a few cells were stained; the average number of stained cells was 14.6 +/- 4.0 cells/mm2. In 48 hours, the number of stained cells increased. The maximum number of stained cells was observed between 48 and 60 hours after the wounding. The number of stained cells decreased rapidly after 72 hours when the wound was almost closed. Stained cells were most numerous in the area within 0.8 mm of the wound edge throughout the wound-healing. The endothelial wound-healing process in this model could be divided into four phases, latent, migration, concurrence of migration and mitosis, and inhibition phases. This in vitro wound-healing model could simulate the wound-healing process in vivo and will be useful for a quantitative evaluation of drug effects on the corneal endothelial wound-healing.

Animals↗
PubMed1990

Clinical application of laser flare-cell meter.

Clinical application of the laser flare-cell meter was described. The instrument was developed for concurrent quantitative determinations of the flare and number of cells in the aqueous humor. Diurnal variations were demonstrated in the aqueous flare, and also an increase in the flare with increasing age. The effects of drugs on aqueous humor dynamics were also studied. Orally administered 500 mg of carbonic anhydrase inhibitor reduced the aqueous humor formation by one-third. Concurrent study with the laser flare-cell meter and slit-lamp microscopy in uveitis cases has revealed that the former instrument is superior to the latter in making a quantitative evaluation of inflammation in the anterior segment of the eye. A follow-up study of postoperative inflammation was performed in patients undergoing extracapsular cataract extraction with posterior chamber intraocular lens implantation. Cases with uneventful postoperative course showed intense flare on the first postoperative day followed by a rapid decrease. Cases with inflammation and fibrin had high aqueous flare which showed an increase even before detection of fibrin in the aqueous by slit-lamp microscopy. Topical 0.5% indomethacin treatment was shown to be effective in suppressing the postoperative increase in aqueous flare but had little effect on cell count. In cases undergoing Argon laser trabeculoplasty, the aqueous flare in the treated eyes was determined to be significantly higher than that in the fellow eyes for four weeks postoperatively (P less than 0.05). The laser flare-cell meter has made it possible to determine the flare and number of cells in the aqueous humor quantitatively. This capability differentiates the instrument from the slit-lamp microscope as well as the instruments previously developed for similar purposes. The laser flare-cell meter is a newly developed useful tool to investigate the pathophysiology of the eye.

Acetazolamide↗
PubMed1990

[Isotonic contraction of rabbit superior rectus muscle].

It is well known that the mammalian extraocular muscle has slow muscle fiber morphologically. But the contraction speed of slow muscle fiber has not been mentioned in previous reports. We studied the isotonic contraction of slow muscle fiber and compared it with fast muscle fiber. Each fiber bundle was isolated from the rabbit superior rectus muscle. Both light microscopic findings and the reaction to isotonic contraction in Ca2+ free Ringer's solution could identify each of the two muscle fiber types. Contraction speed depended on the frequency of stimuli (40-200 Hz) in both slow and fast muscle fiber. Maximum velocities of slow and fast fiber bundles were 4.3 +/- 1.53 mm/sec and 26.9 +/- 3.48mm/sec at 200Hz, respectively. It was suggested that the relaxation of slow muscle fiber did not interfere with the contraction of the fast muscle fiber. The relation between contraction velocity and afterload showed an approximately right angle hyperbolic curve.

Animals↗
PubMed1990

Endothelial specular microscopy in children with retrolental fibroplasia undergoing open-sky vitrectomy.

Thirty-three patients aged 4 to 63 months with extensive retinal detachment due to cicatricial retrolental fibroplasia (RLF) and two non-RLF patients aged 26 and 81 months with normal corneas underwent specular microscopy and ultrasonic pachymetry during examination under anesthesia. Thirty-six eyes of preoperative RLF patients without anterior synechiae and 4 eyes of the two non-RLF patients had high endothelial cell density (ECD) of 5,105 +/- 790.4/mm2 (mean +/- SD) and 4,377 +/- 141.7/mm2, respectively, and increased corneal thickness. The ECD value showed significant negative correlation with vertical corneal diameter (P less than 0.005), but not with age. The ECD values, corrected to average adult corneal size, were 3,900 +/- 550/mm2, which were close to values extrapolated from adult ECD data. The average cell loss for 10 eyes undergoing specular microscopy before and after open-sky vitrectomy was 15%, but 8 of these eyes showed an unchanged ECD ratio of 0.79-1.3 between the two measurements. Furthermore, 17 eyes which were examined only postoperatively also showed a high average ECD of 4,175 +/- 1,012/mm2.

Cell Count↗
PubMed1989

Accuracy of memory-guided saccades.

Accuracy of saccades toward a remembered target positions in the dark (memory-guided saccades) was studied in 11 normal subjects. The subjects were instructed to execute saccades with amplitudes of 20, 40, 60, and 80 degrees, centering on the primary position. Saccades were initially performed for 30 s with visual fixation targets. The targets were then switched off. The subjects continued saccades in the dark with the given amplitude. Most memory-guided saccades overshot the target. Saccades with an amplitude error of 12.7 +/- 7.3 degrees (mean +/- SD) were followed by corrective saccades, while no corrective saccades occurred following saccades with an error of 4.3 +/- 4.0 degrees. The accuracy of initial memory-guided saccades decreased with time. However, the amplitude of the memory-guided saccades was corrected when the error was beyond about 5 degrees. These results suggest that memory-guided saccades are not repetitions of visually guided saccades, but nonvisual error signals relate to the control of eye movements in the dark.

Adult↗
PubMed1989

[Quantitative assessment of aqueous flare intensity and cell count in uveitis].

In an attempt to evaluate the validity of the laser flare-cell meter in in iridocyclitis, we conducted a comparative study of slit-lamp examination and flare-cell meter measurements in 251 eyes of uveitis patients. A significant correlation was observed between the two methods both in the measurement of flare intensity (Kendall tau = 0.580, p less than 0.001) and cell count (tau = 0.390, p less than 0.001). However, there were wide variations in grading within groups and large overlaps in scores between groups. These results were thought to be attributable to differences in the two examination methods. Flare-cell meter demonstrated high sensitivity for flare measurements, while there were some cases where low numbers of cells, which could be observed by a slit-lamp, were undetectable by the flare-cell meter. Patients with Behçet's disease were divided into three groups based on the interval from an ocular attack episode. Flare-cell meter examination revealed that flare intensity values remained abnormally high even in patients free from an attack episode for more than six months prior to the examination (p less than 0.001). It was considered that disruption of the blood-aqueous barrier exists permanently in patients with Behçet's disease.

Adult↗
PubMed1989

Aqueous flare intensity and age.

The influence of aging on the blood-aqueous barrier function was assessed by measuring aqueous flare intensity in 203 normal eyes of healthy human subjects aged 20 to 79 years, using the recently developed laser flare-cell meter. The flare intensity correlated well with age (r = 0.502, Spearman r = 0.503, P = 0.00), and the intensity values in the subjects with their ages in the 6th, 7th and 8th decade were significantly higher than the values in the subjects in their 3rd decade (P less than 0.01).

Adult↗
PubMed1989

[Kinetic study of cell proliferation in a new wound healing model using tissue cultured corneal endothelial cells].

We studied cell kinetics in the wound healing process using cultured bovine corneal endothelium. We cultured bovine endothelial cells on coverslips coated by hydroxyethyl methacrylate (HEMA) which had on 8 mm HEMA-free zone in diameter, and produced wounds at the center of the monolayer cell sheets using a rotating silicone tip. At various time periods after injury, we added bromodeoxyuridine (BrdU) to the medium and incubated for 12 hours. Then, the specimens with fixed 10% phosphate-buffered formalin and were incubated with a monoclonal antibody against BrdU. The cells incorporating BrdU into DNA were stained by the Avidin Biotin Peroxidase Complex (ABC) method. At 12 hours, no labeled cells were observed. At 24 hours, 14.6 +/- 4.0 cells were stained. The maximum labeling occurred during 48-60 hours after the wound. Seventy two hours after the wound, labeled cells decreased rapidly. Labeled cells were localized within 0.6mm from the wound edge throughout the wound healing process. It can be thought that the wound healing process comprised four phases, i.e., latent, migration, migration plus mitosis, and contact inhibition phases. The first is the latent phase observed during the first six hours after wound infliction. The cells respond to external expansion. The second phase in the migration phase which is last until 24 hours after wound infliction, and occurs mainly through cellular migration, while proliferation has only a minor contribution in this phase. The third is the migration plus mitosis phase. The cell proliferation shows a rapid increase after 72 hours after wound infliction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Effect of acetazolamide on aqueous flare in normal human eyes].

A newly developed instrument for the quantitative measurement of aqueous flare, the laser flare-cell meter, is now being introduced clinically. The present experiment was designed to assess the effect of a commonly administered drug, acetazolamide, on measurements obtained in normal, healthy subjects. Control measurements were taken over a 24 hr period, from 0900 hrs to 0900 hrs of the next day in 12 drug-free, normal, healthy subjects. A second, similar time-course measurement was conducted in the same subjects on another day after oral administration of 500 mg acetazolamide. Results revealed that acetazolamide increased aqueous flare from 2 hrs to 10 hrs post-administration. The peak effect was observed approximately 6 hrs after acetazolamide administration, reaching a level 41% greater than that on the control day. Anterior chamber volume and serum protein concentration were not affected by the drug treatment. The use of the laser flare-cell meter in the clinic and possible mechanisms contributing to the effect of the drug are discussed.

Acetazolamide↗
PubMed1989

[Increasing of aqueous flare intensity with aging in normal human eyes].

An attempt was made to evaluate the influence of aging on aqueous flare intensity by measuring 203 normal human eyes. Subjects were divided into six age groups from twenty years to seventy nine years old, and the values for aqueous flare intensity were then determined by a flare-cell meter. Flare values were higher in the older age groups and correlated well with age (linear correlation coefficient r = 0.506, Spearman r = 0.510, p = 0.000). Subjects in their fifties, sixties and seventies showed statistically significant differences to those in their twenties (p less than 0.01). A preliminary in vitro experiment was performed to convert the flare-cell meter reading (photon count/msec) into bovine albumin concentration (mg/dl), which is necessary to compare measurements of different flare-cell meters. The three flare-cell meters employed in this study all showed good linear relationships between photon count and albumin concentration (r = 0.99-1.00), giving converting equations of Y = -0.72 + 0.969 X, Y = -0.68 + 0.958 X, Y = -0.84 + 1.017 X less than Y = log (photon count), X = log (albumin concentration) greater than, respectively. In this report, flare values are expressed in albumin concentrations for each age group, which will then serve as control values in future studies.

Adult↗
PubMed1989

Quantitative assessment of aqueous flare and cells in uveitis.

Validity of the laser flare-cell meter in uveitis was evaluated. A comparative study of slit-lamp examination and flare-cell meter measurements was carried out in the evaluation of iridocyclitis in a total of 251 measurements in patients with uveitis of various etiologies, including Behçet's disease, Vogt-Koyanagi-Harada's disease and sarcoidosis. The data obtained by these two methods showed a significant overall correlation both in the measurement of flare intensity (Kendall tau = 0.580, P less than 0.001) and cell count (tau = 0.390, P less than 0.001). Problems inherent to the slit-lamp examination were marked in terms of wide variations in grading within groups and large overlaps in scores between groups. The flare-cell meter was highly reliable in the measurement of flare intensity; whereas it could not detect low numbers of cells in some cases. Ninety-one eyes of patients with Behçet's disease were divided into three groups based on the interval from the last ocular attack episode. The flare-cell meter examination revealed that values for flare intensity remained abnormally high even in patients free from an attack episode for more than six months prior to the examination. It was considered that deterioration or breakdown of the blood-aqueous barrier function persists in patients with Behçet's disease.

Aqueous Humor↗
PubMed1988

Respiratory fluctuations of the human pupil.

We simultaneously recorded respiration and pupil size in six normal subjects with an age range of 23-40 years (mean = 30.1), to study the relationship between the respiratory rhythm and changes in pupil size. In all subjects, respiratory fluctuations of the pupil (inspiratory mydriasis and expiratory miosis) were observed during normal spontaneous respirations. The amplitude of these pupillary changes was closely proportional to the tidal volume.

Adult↗
PubMed1988

A study of liver regeneration using fetal rat liver tissue transplanted into the spleen.

The liver morphology of fetal hepatic tissue transplanted into an ectopic location was investigated over one year period. Fetal liver fragments prepared from a maternal rat on the 18th or 19th day of pregnancy were injected into the splenic parenchyma of syngeneic rats using a 21 gauge needle. Histologically, the fetal liver did not essentially show any apparent lobular architecture or cord structure. The transplanted fetal hepatic tissues survived and formed hepatic cords in the spleen instead of undergoing degeneration and necrosis. Three characteristic features became complete during the 4 weeks following transplantation, namely; clumps of hepatocytes with obvious hepatic cords and sinusoids, markedly proliferating bile ducts and proliferating individual hepatocytes. Macroscopic nodules of the hepatocytes on the spleen were seen at about 6 months after transplantation. When the differentiation of the transplanted fetal hepatic tissue was compared with the development of a normal neonatal liver after birth, it was delayed by only about one week, while there was no proliferation of bile ducts in the normal neonatal liver. This experimental model provides a useful system for investigating liver regeneration and the mechanism of cell growth.

Animals↗
PubMed1988

Nonvisual eye position control in a patient with ocular lateropulsion.

For elucidating the nonvisual eye position control system, we studied the accuracy of saccades toward the remembered position (memory-guided saccades) in a patient with ocular lateropulsion having tonic bias of the eye position. Although the saccadic dysmetria caused by ocular lateropulsion was recorded during memory-guided saccades in the same manner as visually guided saccades, the eyes reached precisely the intended position by corrective saccades. The mean latency of corrective saccades was significantly longer than that of corrective saccades observed for visually guided saccades. This long latency of corrective saccades supports the assumption that feedback information of the eye position is a signal generated by orbital afferents rather than a copy of the motor command.

Eye Movements↗
PubMed1988

New quantitative method to determine protein concentration and cell number in aqueous in vivo.

We have developed a new quantitative method to determine protein concentration and number of cells in the aqueous in vivo. The principal instruments in the system were a He-Ne laser and a detection system for measuring scattered light intensity. The power of the He-Ne laser was 25 microW and the focused beam diameter was 20 microns. The laser beam was operated by an optical scanner. The sampling window, 0.3 X 0.5 mm, was fixed in the center of the laser path. For the protein concentration measurement, the laser beam was scanned for a length of 0.6 mm vertically, covering the sampling window. To minimize signal contamination by background laser scattering, scattered light intensity produced by aqueous protein (Sp) was calculated as follows. Sp = Si - (S'o + S''o)/2, where Si indicates scattered light intensity when the beam passed in the sampling window and S'o and S''o indicate scattered light intensity when the beam passed above and below the sampling window. For the cell counts, the laser beam (0.25 X 0.6 mm) was scanned over the sampling window and the detected peaks were counted. Each measurement mode took 0.5 seconds. The operation of the instrument and data analysis were performed by a personal computer. In in vitro measurements with human plasma solution in diluting factors ranging from 1/50 to 1/10(4), and bovine serum albumin solution in concentrations ranging from 1 g/100 ml to 1 mg/100 ml, significant linear correlations between the values for concentration and photon counts (/msec) were obtained in each solution (r, ranging from 0.987 to 0.998, P = 0.000). In in vitro experiments with latex particles with diameters of 2.02 or 2.95 microns, significant correlations between the number of detected peaks and latex particles were also obtained. However, as the number of latex particles decreased, the variation in the number of detected peaks was large. In 31 normal young adults, with an average age of 23 years, the average photon count was 4.1 +/- 1.0, which corresponded to 27 mg/100 ml according to the in vitro bovine albumin solution measurement, and there was no definite relation in photon counts between eyes with and without mydriatics. Twenty patients with incipient or immature cataract, whose ages averager 70 years, showed significantly higher average photon counts, 6.2 +/-2.5, than the above young adults.We concluded that this new method of determining protein concentration and cell number in the aqueous enabled us to make a noninvasive and quantitative evaluation of the inflammation in the anterior segment of the eye.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗