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Biomedical subjects

C W Chen

Publications and source records attributed to C W Chen.

At least 127 records · Page 7Linked to original sources
PubMed1991

The effects of epidermal growth factor and chondroitin sulfate on the animal corneal endothelial cell culture.

In order to investigate the effects of different culture media containing various concentrations of epidermal growth factor (EGF) and chondroitin sulfate (CDS) on the growth of cultured corneal endothelial cell, pig corneal endothelial cells were used for this study. The cells were divided into 7 groups and each group was cultured with a medium containing: 1. Eagle's minimal essential medium with Earle's salt (EMEM) only; 2. EMEM + EGF (10 ng/ml); 3. EMEM + EGF (100 ng/ml); 4. EMEM + CDS (1 mg/ml); 5. EMEM + CDS (25 mg/ml); 6. EMEM + EGF (10 ng/ml) + CDS (1 mg/ml); 7. EMEM + EGF (100 ng/ml) + CDS (25 mg/ml), respectively. The results are shown below: (1) High concentration of EGF (100 ng/ml) stimulated the growth of pig corneal endothelial cells, shortened doubling time and the cells reached confluence earliest in group 3. But a low concentration of EGF (10 ng/ml) showed no effects on the growth of pig corneal endothelial cells. (2) A high concentration of CDS (25 mg/ml) might retard the growth of pig corneal endothelial cell, but a low concentration of CDS (1 mg/ml) has no retarding effects on the growth of pig corneal endothelial cells. (3) A high concentration of EGF could "antagonize" the CDS induced growth retarding effects of endothelial cells. (4) Those cells cultured with a medium containing high concentrations of EGF had more mitotic activity, including many prominent binuclear and polynucleolar cells. (5) The cells cultured with a medium containing high concentrations of CDS showed a more flat-shaped morphology under observation with a phase contrast microscope.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Ocular refraction and its components among younger children in Kaohsiung: a 4-year longitudinal study.

A four-year longitudinal study was made on refraction and its components among 50 children of Kaohsiung, Taiwan, R.O.C. aged from 7 to 10.6 years. The methods of examination of the eyes were the same as that of four years ago, including Mydriacyl refraction, keratometry for corneal curvature radius, and ultrasonic measurement of the refractive components. One eye with amblyopia was excluded. The results of our study showed that all of our cases over 6 years of age had a corrected visual acuity of 0.8 or better, and that the refractive state shifted to myopia in our 4-year follow up. The rate of myopia increased from 2% to 27.3%. Comparisons of refractive components between the years 1983 and 1987 showed significant increases in refractive power, length of vitreous cavity and total axial length of the eyes. Corneal refractive power and lens thickness, however decreased significantly. As for differences in gender, several results were the same for both 1983 and 1987: corneal curvature radius, the length from anterior corneal surface to anterior lens surface, length of vitreous cavity and total axial length were larger in males than females. Finally, total axial length and corneal curvature radius were the factors most affecting the refractive state in younger children.

Child↗
PubMed1990

The melanin operon of Streptomyces antibioticus: expression and use as a marker in gram-negative bacteria.

The melC operon of Streptomyces antibioticus contains two genes, melC1 and melC2, necessary for the production of melanin pigment. We transferred the coding sequence of melC1 and melC2 to Escherichia coli plasmid pMTL23 such that its transcription was under the control of the lac promoter and melC1 was translationally fused to the lacZ alpha fragment. E. coli cultures containing this plasmid, pIF413, produced melanin after overnight incubation on 2YT agar supplemented with 0.1 mM CuCl2, 0.36 mM IPTG (or 0.2% lactose), and 2 mM tyrosine. Erwina carotovora could also be transformed by pIF413 to produce melanin. Two shuttle vectors were constructed: pLUS415 for E. coli and Streptomyces, and pLAF413 for E. coli and Xanthomonas campestris. These vectors confer melanin pigmentation in all the hosts that harbor them. The melC sequence provides the vectors with a convenient cloning marker for insertional or replacement inactivation.

Catechol Oxidase↗
PubMed1990

Evolutionary study on the Coxsackievirus A 24 variant causing acute hemorrhagic conjunctivitis by oligonucleotide mapping analysis of RNA genome.

The evolution of the variant of Coxsackievirus A 24 (CA 24 v) which causes acute hemorrhagic conjunctivitis was explored. Using 15 isolates obtained from Southeast Asia during the period 1970-1986, the genetic distance between isolates was estimated from pairwise comparison of nucleotide changes deduced from common spots on oligonucleotide maps of the isolates. From regression analysis of the genetic distance and the time of isolation of the isolates, the evolutionary rate of CA 24 v was estimated to be 3.44 x 10(-4)/nucleotide/month. The phylogenetic relationship of these isolates was explored using the neighbor-joining method and the modified unweighted pair group method using arithmetic averages (UPGMA). The phylogenetic tree constructed indicates that CA 24 v appeared from one focal place in July 1968 +/- 25 months, very close to the time of the first world epidemic of, then newly recognized, acute hemorrhagic conjunctivitis.

Asia, Southeastern↗
PubMed1990

Trabeculectomy with simultaneous topical application of mitomycin-C in refractory glaucoma.

From May 1981 to Feb. 1989 trabeculectomy with per-operative topical application of mitomycin C was performed on eyes with refractory glaucoma. All eyes had undergone prior one, two or more than two antiglaucoma surgeries without success for IOP control. Other risk factors in the present series of eyes included young age, aphakia, rubeosis and glaucoma secondary to trauma or associated with anterior uveitis. 59 eyes underwent trabeculectomy with mitomycin application. 14 eyes were lost. 45 eyes of 42 cases, 33 eyes of 31 males and 12 eyes of 11 females were followed for a period of 1 to 8 years, an average 3.0 +/- 1.9 years. The success for IOP control less than 21 mmHg was 77.8%, 35/45 eyes. The success rates were 92%, 11/12 eyes in females and 73%, 24/33 eyes in males. Complications reported in 5-fluorouracil studies such as corneal epithelial toxicity and delayed healing of conjunctival wound were not encountered. The histo-pathological changes of wound healing after trabeculectomy with topical mitomycin application was discussed. In the healing process success to achieve filtration is more likely by pharmacolocally interferring with earlier steps in the process. We recommend the use of per-operative topical application of mitomycin C during trabeculectomy in eyes with uncontrolled glaucoma and poor prognosis, specifically after previous cataract extraction or unsuccessful antiglaucoma surgery.

Adolescent↗
PubMed1990

Increased plasma prolactin levels in ovariectomized thyroidectomized rats treated with estrogen.

It is well established that TRH exerts a stimulatory effect on the secretion of both TSH and PRL. Clinically, hyperprolactinemia is usually present in hypothyroid women, but not men. In experimental studies, results vary because of the sexes, and treatments of animals differ. The purpose of this study was to further investigate the physiological control of PRL secretion in hypothyroid female rats. Adult female Sprague-Dawley rats that were surgically ovariectomized (OVX) and/or thyroidectomized (Tx) for 2 weeks were used. Serial blood samples were collected through indwelling intraatrial catheters, and plasma PRL and TSH levels were measured by RIA. We found that OVX + Tx and polyestradiol phosphate (PEP; 0.1 mg/rat, sc)-treated rats exhibited significantly higher basal PRL and TSH levels and afternoon surge PRL levels than sham Tx rats with the same treatments. On the other hand, if OVX + Tx rats were not treated with estrogen, their plasma PRL levels were not significantly different from those in sham Tx controls. If challenged with TRH (1 microgram/rat, iv), significantly higher PRL responses were found in OVX + Tx + PEP rats than in sham Tx rats. The contents of TRH in the median eminence of Tx rats, however, were not different from those in sham Tx rats. When challenged with domperidone (10 micrograms/rat, iv), a dopamine antagonist, no difference in PRL increments was found in the two groups of animals. Treatment with CB154, a potent dopamine agonist, did not eliminate the difference in basal PRL levels between the two groups. Pretreatment with a smaller dose of domperidone (1 microgram/rat), however, enhanced the PRL-releasing effect of TRH more in Tx than in sham Tx rats. When T4 (2 or 10 micrograms/100 g BW.day for 21 days) was replaced in Tx rats starting the second day after Tx, both basal and TRH-stimulated PRL secretion were significantly decreased in a dose-dependent manner. In conclusion, the increased PRL levels in OVX + Tx + PEP rats may be due to increased responsiveness of the anterior pituitary gland to TRH, and not to a decreased responsiveness to dopamine. In addition, the elevation of plasma PRL in OVX + Tx + PEP rats is negatively correlated with plasma levels of thyroid hormone.

Animals↗
PubMed1990

[Menkes' kinky hair disease: report of 2 cases].

Menkes' kinky hair disease (trichopoliodystrophy) is a rare inherited X-linked recessive disease with an incidence of about 1:35,000, and is rare reported previously in Taiwan. We present 2 cases with typical features including sparse, coarse and stubby, kinky hair, depigmented skin, pudgy face, arrow-shaped upper lip, hypotonia, Babinski signs bilaterally, profound psychomotor retardation with disability of head control or rolling over, and poorly controlled myoclonic jerks. Both were male infants with a family history of male relatives died in early childhood. Their hairs showed pili torti and trichorrhexis nodosa microscopically. Serum levels of copper were 14 ug/dl and 20 ug/dl. Ceruloplasmin levels were 10.4 mg/dl and less than 7 mg/dl. Their EEG showed abnormal generalized brain polyspike waves. Brain CT scan showed generalized brain atrophy, and chronic subdural hematoma in case 1. Bilateral urinary bladder diverticula and spurs over the distal ends of the femoral diaphysis were found in case 1. Normal urinary bladder was found in case 2 initially, then diverticula developed one year later. They are currently on anticonvulsants (Rivotril) therapy. Repeated attacks of respiratory infection, myoclonic seizure, hypotonia, and static neurologic developmental status are noted.

Humans↗
PubMed1990

Time spent and satisfaction of new out-patients in Department of Internal Medicine. Kaohsiung Medical College Hospital.

To assess the time spent and the degree of satisfaction of new clinic patients, one hundred and nine new out-patients from the Internal Medicine Clinic of Kaohsiung Medical College Hospital were studied from January 30th to February 6th, 1985. Both accurate field recording and telephone interviews concerning the time spent for each procedure and satisfaction with the medical personnel and expense in their first visits were carried out. The total time spent was 152 +/- 65 minutes (mean +/- SD) from questionnaire and 126 +/- 56 minutes from field recording. According to field recording, time spent in waiting for registration was 39.8 +/- 42.9 minutes. Most (55%) of study patients spent more than one hour in waiting for consultation. The time spent in waiting for filling prescription was 17 +/- 6 minutes. The accessibility of the paramedical examination units was good. The degree of satisfaction was measured by a five point rating scale for series of questions. The response were "very satisfied" or "satisfied" with professional services but not medical expense and cashier attitude. According to our results, some of our attempts to innovate service have been done including an appointment system, colored directional arrowheads, and changing our schedule to opening 30 minutes earlier.

Appointments and Schedules↗
PubMed1990

[Intraocular lens implantation at Kaohsiung Medical College].

Between March 1984 and December 1987, 993 cataractous eyes in 884 patients (462 males, 422 females) were operated on using intraocular lens implantation at the Kaohsiung Medical College Hospital. The age of the patients ranged from half year to 93 years, with an average of 61.9 years. Primary lens implantation was performed in 98.4% of the cases, secondary implantation in 1.6% of the cases. There were 6 cases were done by using the triple procedure (combined keratoplasty with cataract extraction and intraocular lens implantation). Among these 742 eyes followed-up for from one to 43 months, final vision could be corrected to 6/12 or better in 63.5% of the cases. While 64.4% of the cases of post-operation cylinder were less than 2 diopters, the final refraction showed that the spherical equivalent diopters were within 2 diopters in 61.7% of the cases. Complications in the anterior chamber lens group included pupillary changes (21.2%), pseudophakic bullous keratopathy or decompensation (13.5%), lens subluxation or dislocation (13.5%) and cystoid macular edema (5.8%). Complications in the posterior chamber lens group included pupillary changes (16.2%), posterior capsular thickening (3.2%), anterior or posterior synechiae (2.7%) and lens subluxation or dislocation (2.8%).

Adolescent↗
PubMed1989

Incorporation of biological information in cancer risk assessment: example--vinyl chloride.

Vinyl chloride (VC) is used as an example to demonstrate how biological information can be incorporated into quantitative risk assessment. The information included is the pharmacokinetics of VC in animals and humans and the data-generated hypothesis that VC primarily affects the initiation stage of the multistage carcinogenesis. The emphasis in this paper is on the improvement of risk assessment methodology rather than the risk assessment of VC per se. Sufficient data are available to construct physiologically-based pharmacokinetic models for both animals and humans. These models are used to calculate the metabolized dose corresponding to exposure scenarios in animals and in humans. On the basis of the data on liver angiosarcomas and carcinomas in rats, the cancer risk per unit of metabolized dose is comparable, irrespective of routes (oral or inhalation) of exposure. The tumor response from an intermittent/partial lifetime exposure is shown to be consistent with that from a lifetime exposure when VC is assumed to affect the first (initiation) stage of the multistage carcinogenic process. Furthermore, the risk estimates calculated on the basis of animal data are shown to be consistent with the human experience.

Administration, Inhalation↗
PubMed1989

A mutation of Streptomyces lividans which prevents intraplasmid recombination has no effect on chromosomal recombination.

A mutation (rec-46) of Streptomyces lividans, previously shown to prevent (or greatly diminish) homologous and illegitimate intraplasmid recombination, was shown to have no effect on generalised chromosomal recombination occurring in matings or in protoplast fusions, nor to affect homologous recombination between a recombinant plasmid and the host chromosome. By comparison with Escherichia coli mutants defective in various aspects of recombination, the rec-46 mutation is similar to those in recF, recJ, recO and topA.

Chromosome Mapping↗
PubMed1989

A dose-response analysis of skin cancer from inorganic arsenic in drinking water.

A study of the prevalence of skin cancer among 40,421 persons consuming arsenic-contaminated drinking water in Taiwan was used for a cancer dose-response assessment of ingested arsenic. The numbers of persons at risk over three dose intervals and four exposure durations were estimated from the data in order to apply the method of maximum likelihood to a multistage-Weibull time/dose-response model. A constant exposure level since birth for each of the exposure categories was assumed. It was found that the cumulative hazard increases as a power of three in age, and is linear or quadratic (with a linear coefficient) in dose. Observations from a smaller epidemiologic survey in Mexico were similar to what would be predicted from the model of the Taiwan data. Assuming that the skin cancer risk from ingested arsenic in the American population would also be similar to the Taiwan population, an American male would have a lifetime risk of developing skin cancer of 1.3 x 10(-3) (3.0 x 10(-3] if exposed to 1 microgram/kg/day for a 76-year lifespan (median lifespan in the U.S.).

Adult↗
PubMed1989

Photo-switchable ion and enzyme sensors. Photoinduced potentiometric response of glassy carbon electrode coated with polymer or polymer/enzyme dual membrane.

Photo-switchable ion and enzyme sensors were fabricated by the use of glassy carbon electrode coated with nonactindoped or enzyme modified poly(vinyl chloride) (PVC) membranes. The ion sensor with nonactin-doped PVC membrane, which contained spirobenzopyran as the photosensitive dye, exhibited a potentiometric photoresponse to NH4+ ion in the solution. The dynamic range of the NH4+ ion sensor was 10(-7)--10(-3) M. Urea, adenosine, and asparagine sensors were prepared by coating the surface of the NH4+-ion sensor with urease, adenosine deaminase, and asparaginase membranes, respectively. These enzyme sensors could be used for determining the substrates at the micro mole level. The performance characteristics of these sensors were compared with those previously prepared membrane electrode sensors.

Carbon↗
PubMed1989

Vibrio vulnificus infection.

We report 3 cases of Vibrio vulnificus infections from Taiwan. Patient 1, who manifested symptoms of primary septicemia, died after 2 days. Patient 2, who had a wound infection and signs and symptoms of sepsis but negative blood cultures, responded to tobramycin and chloramphenicol plus surgical debridement, and recovered after 26 days of hospitalization. Patient 3 had secondary septicemia originating from a wound inflicted by a shrimp. Originally, the patient seemed to respond to ceftazidime and amikacin treatment along with surgical debridement, but subsequently died from adult respiratory distress syndrome (ARDS) induced by several episodes of aspiration which occurred after initial clinical improvements. We conclude that, for patients with severe wounds and evidence of V. vulnificus infection, an appropriate, powerful antibiotic, such as one of the third generation cephalosporins should be used as initial therapy unless the nature of the infection indicates other treatment.

Adult↗
PubMed1989

[Adverse side effects caused by topically applied antiviral agents in herpetic keratitis].

The present paper reviews the adverse side effects caused by topically applied antiviral agents in herpetic keratitis. The effective treatment of herpetic keratitis with IDU, a chemotherapeutic agent, was first reported in 1962. After its introduction into ophthalmic therapy for herpetic keratitis, drops of IDU were administered every hour by day combined with ointment every two hours by night. The therapy often continued for months or in some cases, even more than one year. Numerous reports on its side effects have appeared. The side effects can be classified into two categories. The first category is allergic contact blepharodermatitis, a type IV delayed hypersensitivity reaction. Its occurrence is difficult to foresee. This category I side effect rarely results in the destruction of the ocular tissues. The second category of side effects is a drug-induced toxic side effect resulting in punctate epithelial keratitis, papillary conjunctivitis or follicular hypertrophy and lacrimal punctal obstruction. After withdrawal of IDU, these ill effects usually subside soon. When IDU is further continued, the destructive change of the tissues will ensue. Conjunctival cicatrization, symblepharon, corneal neovascularization, cicatrization and irreversible punctal occlusion have been reported in cases with prolonged IDU treatment. In addition to IDU for therapy of herpetic keratitis, we are fortunate to have F3T, Ara-A and acyclovir. They show no cross sensitivity reaction nor any cross toxic reaction to each other. However, if administered more than several times daily and continued for a prolonged period of time, these antiviral agents, like IDU, can also result in reversible side effects and, further, irreversible tissue destruction. Conjunctival cicatrization and permanent punctal occlusion caused by prolonged administration of F3T have been reported. Prompt recognition of the untoward reactions and withdrawal of the antiviral agent will result in the subsidence of the toxic reaction changes and prevent the eye from irreversible destruction. The recognition, prevention and management of the untoward side effects also are discussed.

Acyclovir↗
PubMed1989

[Clinico-etiological observation of 13 cases of mycobacterial keratitis].

We report a series of 13 cases of atypical mycobacterial keratitis encountered in 1986 and 1987. The ratio of mycobacterial keratitis to the total number of corneal ulcer cases increased recently from 1% in 1984 to 8% in 1988 at our clinic. The diagnosis was established by a positive acid-fast stain of smear and a Löwenstein-Jensen media culture. Of the 13 cases, 12 were diagnosed within one week after the first presentation. All cases had a history of corneal trauma; there was foreign body injury in 10 cases, pterygium surgery in 2 cases and penetrating keratoplasty in one case. The clinical pictures of mycobacterial keratitis mostly included anterior stromal infiltrate (100%), necrotic abscess (69.2%), migration lesion (69.2%) and Descemet's folding (61.5%), showing resemblances to fungal keratitis in their characteristics. Species identification showed 11 cases of Mycobacterium fortuitum and 2 cases of Mycobacterium chelonei. On the sensitivity test Rifampin (12 cases, mean 19 mm), Kanamycin (11 cases, mean 29 mm), Ethambutol (11 cases, mean 28 mm), Amikacin (11 cases, mean 19 mm), Netilmicin (9 cases, mean 20 mm) and Tobramycin (8 cases, mean 20 mm) were more effective. Ten of the 13 cases completely healed after treatment and remained quiet during the follow up period of more than one year. In the other 3 cases there was no follow up. We emphasize that the recognition of the clinical features of the corneal findings will facilitate an early diagnosis of this disease and is of essential importance for the salvage of the eye.

Adult↗
PubMed1989

[The ocular fundus findings in dengue fever].

From September to December of 1988, 24 cases of clinical diagnosed dengue fever accompanied by visual disturbances were studied. A detailed history and a detailed ocular examination including visual acuity, slit lamp examination, fundus examination through dilated pupil and fluorescein angiography were conducted. In some cases, Amsler grid, visual field, visual evoked potential and color vision test were also evaluated. The chief complaints of these 24 patients were blurred vision, central scotoma, floaters, photophobia and halo vision. The intervals between onset of fever and awareness of blurred vision were 2 to 15 days with an average of 7.26 days. The ocular fundus changes included macular hemorrhage, retinal hemorrhage, maculopathy, Roth's spot, diffuse retinal edema, peripapillary hemorrhage vitreous cells and blurring optic disc. The fluorescein angiographic findings included poor choroidal flushing, delayed disc filling, disc extravasation, block fluorescence, capillary obliteration, non filling of macular network, capillary leakage and window defect. Seventeen cases (30 eyes) were followed-up for 2 weeks to 3 months. Visual recovery was good in most of the cases. However, 2 cases (4 eyes) showed poor visual outcome. In this series studied, the principle ocular fundus change caused by dengue fever was macular hemorrhage. This may be due to the capillary changes near the macular area. But in some of the cases, the direct viral invasion and/or indirect changes of the optic nerve, the retinal pigment epithelium or photoreceptors should be considered.

Adolescent↗