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Biomedical subjects

J C Tsai

Publications and source records attributed to J C Tsai.

At least 19 recordsLinked to original sources
PubMed1992

An experimental animal model of adenovirus-induced ocular disease. The cotton rat.

The adenoviruses are a common cause of eye disease in humans and clinically cause three basic syndromes: epidemic keratoconjunctivitis, pharyngo-conjunctival fever, and nonspecific follicular conjunctivitis. Although many serotypes of the adenovirus have been implicated, types 8, 19, and 37 are associated most commonly with ocular disease. There has not been a well-defined and reproducible animal model of this disease. The eyes of cotton rats inoculated with either adenovirus type 5 or type 8 developed clinical features similar to those seen in epidemic keratoconjunctivitis, with subepithelial corneal opacities, seroconversion, and virus shedding. The infectivity of adenovirus type 8 in a control animal illustrated the highly contagious nature of the disease. We conclude that ocular inoculation of at least some adenoviruses (ie, types 5 and 8) in the cotton rat produces an in vivo model for the study of adenovirus-induced ocular disease in humans.

Adenoviridae↗
PubMed1992

Drug and vehicle deposition from topical applications: use of in vitro mass balance technique with minoxidil solutions.

The disposition of minoxidil and propylene glycol from topical solutions was measured by using an in vitro mass balance technique. The experimental approach included assessment of the following compartments of the skin and the diffusion cell as a function of time: (1) donor compartment; (2) hairless mouse skin surface, epidermis, and dermis; and (3) receiver compartment. Excellent mass balance was achieved for minoxidil at three doses. However, the recovery of propylene glycol depended on both application volume and time. The experiment involving the evaporation of propylene glycol and water from the propylene glycol:ethanol:water (20:60:20, v/v) mixture, which was placed in the well of a tissue culture plate at room temperature and 37 degrees C, substantiated the loss of vehicles to the air. When a thin application of 20 microL/cm2 was used, 60% of the propylene glycol was unaccounted for after 16 h. The evaporation of propylene glycol concentrated the solution to supersaturation, precipitated out the drug, and then stabilized the thermodynamic activity of the drug in the vehicle. The amount of formulation applied influences the rate of concentration and, thus, the time at which minoxidil precipitates. The precipitation limits the amount of minoxidil that can be absorbed and leads to poor percutaneous absorption of drug from the formulation.

Administration, Topical↗
PubMed1992

Posterior continuous curvilinear capsulorhexis. An experimental study with clinical applications.

The posterior continuous curvilinear capsulorhexis technique has been advocated in cases of posterior capsule rupture during extracapsular cataract extraction. The authors compared posterior continuous curvilinear capsulorhexis with posterior capsular sharp-edged tears. Two different types of forces were experimentally created on the posterior capsule of 30 human eyes obtained after death: (1) implantation and dialing of posterior chamber intraocular lenses (PC IOLs) and (2) increased intravitreal pressure by injection of balanced salt solution. All posterior capsular tears extended toward the equator, causing major capsular defects. In contrast, the posterior continuous curvilinear capsulorhexis remained intact in all cases. This experimental study proves that in cases where an inadvertent posterior capsular tear occurs, a posterior continuous curvilinear capsulorhexis is useful in preventing further capsular damage. Also, in cases where a posterior capsulotomy is indicated, a smooth edge created by a posterior continuous curvilinear capsulorhexis may be useful to maintain the integrity of the capsular bag for PC IOL capsular implantation.

Aged↗
PubMed1992

Removal of viscoelastic materials after experimental cataract surgery in vitro.

The one significant complication of viscoelastic materials is that they may cause postoperative intraocular pressure rise. We investigated the rate and ease of removal of various viscoelastics using the Miyake video technique. Five viscoelastics were investigated: sodium hyaluronate (Healon), Healon GV, chondroitin sulfatesodium hyaluronate (Viscoat), hydroxypropylmethylcellulose (Occucoat), and polyacrylamide (Orcolon). The viscoelastics were dyed with fluorescein and, after filling the capsular bag with a viscoelastic material, a posterior chamber intraocular lens (IOL) was implanted. The viscoelastic was then aspirated using an automated irrigation/aspiration device. Healon and Healon GV were completely removed within 20 to 25 seconds. Viscoat adhered to the lens capsule and to the posterior surface of the IOL and cooplete removal required approximately 3.5 minutes. Most Occucoat and Orcolon was aspirated within one minute; however, removal was completed only after three minutes. Removal of Healon and Healon GV was faster and more complete than removal of the other viscoelastics. Whether a small amount of viscoelastic left in the eye or trapped behind the IOL optic has any clinical significance has to be studied.

Acrylic Resins↗
PubMed1992

Scanning electron microscopic study of modern silicone intraocular lenses.

Silicone, as manufactured today, appears to be a biocompatible material. The safety and efficacy of silicone lenses are primarily related to the intraocular lens (IOL) design. We compared the edge finish of two three-piece polypropylene loop foldable silicone IOL designs (Allergan Medical Optics) and three one-piece designs (Staar Surgical Co., CooperVision-Cilco). Except for an early Staar one-piece design, all lenses including the more recent Staar lenses had acceptably smooth edges with minimal molding flash.

Biocompatible Materials↗
PubMed1991

The elastic properties of the lens capsule in capsulorhexis.

We investigated the ability of the anterior lens capsule to stretch and allow removal of lens substance and intraocular lens implantation through a continuous circular capsulorhexis. Capsulorhexis of various sizes (2.5 to 7.5 mm) were performed in 50 eyes obtained post mortem from 31 patients. The nucleus and cortex were removed by either phacoemulsification (35 eyes) or manual extracapsular cataract extraction (15 eyes). The opening of the capsule was then gradually enlarged, using a modified caliper with two pins attached to its tips, until the margins were torn. The capsule was torn when the circumference at the time of rupture was 1.6 times larger than the circumference of the original circular capsulectomy or 5.0 times larger than the diameter of the capsulectomy. Manual extraction of a lens nucleus with profile circumference (sagittal or anteroposterior) of 18.0 to 22.0 mm can be performed through a 5.5-mm opening and a 6.0- to 7.0-mm optic intraocular lens (profile circumference of 13.0 to 17.0 mm) can be implanted through a 4.5-mm capsulectomy.

Aged↗
PubMed1991

An experimental study comparing various anterior capsulectomy techniques.

Radial tears at the margin of an anterior capsulectomy may be associated with the exit of at least one loop of an intraocular lens out of the capsular bag ("pea pod" effect) and subsequent decentration. Many ophthalmologists have gained a clinical impression that the anterior capsule is more likely to remain intact if the continuous circular capsulorhexis (CCC) technique is used. However, controlled comparison of the incidence of radial tears with the use of different capsulectomies under standardized conditions has not been performed, to date. In this study, we analyzed the incidence of radial tear formation in 40 human eyes that were obtained post mortem. These eyes were randomized to four technique groups: (1) "can opener," (2) linear capsulotomy, (3) capsulopuncture, and (4) CCC. We demonstrated that the CCC technique is much less likely to cause or be associated with anterior capsular radial tears as opposed to the other three techniques. With the technique of nuclear expression used in this study, radial tears occurred in 100% of cases treated with the can opener, linear capsulotomy, and capsulopuncture techniques, whereas no tears occurred with the CCC technique. This study provides convincing evidence that the CCC is the best available anterior capsulectomy procedure to minimize the incidence of radial tears.

Aged↗
PubMed1991

A retrospective study of disposable extended-wear lenses in 100 patients.

A retrospective evaluation of 100 patients who wore disposable extended-wear contact lenses is presented. The patients were selected at random and were fitted with one of three lens brands approved for extended wear. There were 37 males and 63 females in the study. The mean age was 40.1 years (range, 14 to 76 years). Sixty-seven of the patients wore nondisposable extended-wear soft contact lenses before being fitted with disposable lenses. Complications were noted and included two instances of infectious ulcerative keratitis and six cases of peripheral corneal infiltrates. It is believed that the rate of complications is due to the ongoing hypoxic effect of prolonged use of extended-wear or other contact lenses and may be improved by providing a greater variety of lens fitting parameters. Disposable extended-wear lenses may be a reasonable means of vision correction in the appropriately selected patient and with proper follow-up. At the same time, caution should be exercised in the fitting and wear of disposable extended-wear lenses.

Adolescent↗
PubMed1991

Mechanism of radial tear formation and extension after anterior capsulectomy.

The mechanisms of anterior capsular radial tear formation and extension around the equator onto the posterior capsule were investigated in 57 eyes obtained postmortem. Experimental radial tears were created by gradual opening of a caliper. In 95% of cases, the tear immediately reached the equator but none extended to the posterior capsule. The elastic forces of the zonules attached to or crossing the edges of the tear resisted a widening of the gap between the edges and thus limited the radial progression of the rupture. A significantly stronger force and severing of the zonules were necessary for a tear to extend around the equator. The authors have determined that radial tears in the anterior capsule seldom extend around the equator, providing the zonules bridging the tear are intact. There is a diminution of the tearing force when the flaps are widely open. Careful surgery with preservation of the integrity of the capsular-zonular apparatus is a major factor in preventing major complications such as posterior capsular ruptures.

Aged↗
PubMed1991

Anterior capsular tears and loop fixation of posterior chamber intraocular lenses.

Two hundred fifty consecutive postmortem eyes containing posterior chamber intraocular lenses (PC IOLs) were analyzed according to the presence and number of radial anterior capsular tears. Over 90% of cases had been done with the "can opener" technique. A surprisingly high percentage of cases, 86%, had one to five radial tears. Furthermore, our analysis showed that the most consistent and most permanent in-the-bag fixation was achieved when only one tear or less was present in the anterior capsule. Because this study shows that the incidence of radial tears is very high after nuclear expression with "can opener" capsulectomy, it provides a scientific basis supporting the transition toward the continuous circular capsulorhexis technique that is slowly evolving. The latter technique has been shown to minimize the incidence of anterior capsular radial tears. This may ultimately serve to decrease the incidence of PC IOL decentration, an important goal if the use of bimultifocal IOLs and IOLs with small or aspheric optics is to be successful.

Aged↗
PubMed1991

An analysis of flexible anterior chamber lenses with special reference to the normalized rate of lens explantation.

A survey of 1204 closed-loop anterior chamber intraocular lenses (AC-IOLs) and 310 open-loop AC-IOLs accessioned between November 1982 and January 1990 was conducted at the Center for Intraocular Lens Research. An analysis of complication rates was done after normalization of data with respect to market share totals. The results establish that an unacceptable complication rate is associated with the closed-loop design when compared with either the tripod or quadripod lens styles. Furthermore, the closed-loop designs, while comprising an estimated 45% of the total number of AC-IOLs estimated to be implanted in the United States (n = 674,000), were responsible for 80% of the AC-IOLs explanted after complications and accessioned at the authors' center. A rethinking of the extreme condemnation of all anterior chamber IOLs that has surfaced in recent years is warranted. This is particularly true with respect to indications for use of sutured posterior chamber (PC) IOLs as well as with regard to possible use of open-loop AC-IOLs in less-industrialized nations.

Anterior Chamber↗
PubMed1991

[An epidemiological study of head injury in Hualien County, Taiwan].

An epidemiological study of head injuries in Hualien County, Taiwan, was undertaken from July 1, 1987 to June 30, 1988. Clinical records, including emergency room (ER) charts, inpatient charts from the four major hospitals and coroner or medical examiner reports in this county, were reviewed. A formulated definition was used in identifying patients with head injury. A total of 1,183 cases were identified. They included 975 hospital inpatients and 208 nonhospital deaths. The age-adjusted incidence rate for head injuries was 333/100,000 for all, 450/100,000 for males and 194/100,000 for females, with a male-to-female ratio of 2.32. The cumulative incidence rate from 0 to 69 years of age was 27.6% for males and 13.7% for females. The highest incidence rate was observed in the elderly group, whereas in other published reports the highest occurrence has been noted in the young adult group. An extraordinary 82% of the head injuries were associated with traffic accidents, 71% of which directly involved motorcycle riders. The age-adjusted mortality rate was 89/100,000 per year, 127/100,000 for males and 44/100,000 for females. The cumulative mortality rate was 8.7% for males and 3.2% for females. These are the highest rates ever reported. Sixty percent of the 1,183 patients had a moderate to severe injury or were dead. In the remaining 40%, the injury was considered mild. The elderly group presented with the highest percentage of moderate to severe degrees of injury, as well as mortality. Among traffic accident victims, those from motorcycle accidents and pedestrians had the highest percentage of severe head injuries.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Clinical efficacy of recombinant human erythropoietin in the treatment of anemia in hemodialysis patients: influence of dosing regimen, iron status, and serum aluminum.

To evaluate the clinical efficacy of recombinant human erythropoietin (EPO) and its influencing factors in the treatment of anemia in hemodialysis (HD) patients, 17 chronic stable HD patients (10 males, 7 females; mean age: 46.0 +/- 2.6 years) with severe anemia were enrolled in this study. The study period (ranging from 5 to 11 months) was divided into the initial 12 weeks of correction phase and the subsequent maintenance phase. EPO, 1500 U initially, was administered intravenously twice weekly (BIW group, n = 10) or thrice weekly (TIW group, n = 7) at the end of each HD. Dose was doubled every 4 weeks until up to a maximum dose of 6000 U if increment of hematocrit (Hct) was less than 3%. At the end of correction phase, anemia was markedly improved. Hct and hemoglobin (Hb) increased from 19.3 +/- 0.8 to 28.7 +/- 1.1% and from 6.5 +/- 0.3 to 9.6 +/- 0.4 g/dl, respectively. Fifteen patients (88%) reached to the target Hct of 30% at 13.7 +/- 1.2 weeks. At the end of study, Hct and Hb was maintained at 29.1 +/- 0.7% and 9.6 +/- 0.3 g/dl, respectively. Requirement of EPO dose to reach the target and maintain the stable Hct (greater than or equal to 28%) was 99 +/- 14 and 62 +/- 11 U/kg/week, respectively. Laboratory parameters showed that serum iron, transferrin saturation, sugar and triglyceride decreased significantly and uric acid and aluminum (Al) increased significantly. There was no significant change in predialysis blood pressure, body weight, cardiac ratio, and ECG. Quality of life was markedly improved with the better subjective feelings, physical activity and Karnorfsky index. Common adverse effects included exacerbated hypertension (23%), hyperphosphatemia (18%), hyperkalemia (18%), and flu-like syndrome (12%). All of them could be managed by medical and dialysis treatment. Investigation of influencing factors on response to EPO suggests that 1) TIW group had a better response than BIW group 2) Response was better in patients with more adequate iron status and less severe Al burden. 3) Time to target Hct correlated approximately with basal serum Al levels but did not correlate with basal serum parathyroid hormone levels. In conclusion, low dose of EPO therapy corrects anemia effectively with minimal adverse effects in HD patients. Dosing regimen, iron status, and serum Al will influence the response to EPO.

Adult↗
PubMed1990

Preparation and study of human eyes obtained postmortem with the Miyake posterior photographic technique.

A modification of the original Miyake technique of posterior photography of human eyes obtained postmortem is presented. A detailed description of globe preparation and equipment is described. Use of modern technology including a high magnification microscope system and video camera permits dynamic or realtime observations of tissue effects of various surgical procedures such as the cataract operation. This technique provides both a research and educational tool that can be used by ophthalmologists to improve the quality of surgery. Most important, it is an instructional tool that should reduce the "learning curve" that is inherent when modifying one's surgical technique.

Eye↗
PubMed1990

Fluid-fluid level: a nonspecific finding in tumors of bone and soft tissue.

Fluid-fluid levels have commonly been reported to occur in aneurysmal bone cysts but have also been seen in telangiectatic osteosarcoma, chondroblastoma, and giant cell tumor of bone. The authors reviewed their experience with nine bone and three soft-tissue tumors that showed fluid-fluid levels on computed tomographic or magnetic resonance images. The bone tumors included fibrous dysplasia, simple bone cyst, recurrent malignant fibrous histiocytoma of bone, two classical osteosarcomas, and four aneurysmal bone cysts. The soft-tissue tumors included soft-tissue hemangioma and two synovial sarcomas. Except for aneurysmal bone cysts, these types of tumors have not been reported to be associated with fluid-fluid levels. Radiologic-pathologic correlation was available in seven patients; in all seven, the fluid-fluid levels indicated prior hemorrhage. The authors conclude that the presence of fluid-fluid levels in bone or soft-tissue tumors cannot be considered diagnostic of any particular tumor.

Adolescent↗
PubMed1990

Magnetic resonance imaging of the shoulder.

Magnetic resonance imaging is rapidly becoming the procedure of choice to evaluate the shoulder. This article reviews the relevant technical, anatomic, and pathologic features important in imaging the joint with magnetic resonance, with an emphasis on rotator cuff disease and shoulder instability.

Humans↗