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Samuel C Yiu

Publications and source records attributed to Samuel C Yiu.

7 recordsLinked to original sources
PubMed2007

Tissue-engineered tear secretory system: functional lacrimal gland acinar cells cultured on matrix protein-coated substrata.

Dry eye is a general term that refers to a myriad of ophthalmic disorders resulting in the inadequate wetting of the corneal surface by the tear film. Dry eyes are typically treated by the application of artificial tears. However, patients with lacrimal insufficiencies such as Stevens-Johnson syndrome, chemical and thermal injuries, or ocular cicatricial pemphigoid have very limited options because of the short duration and action of lubricating agents. As a therapeutic strategy, we are working to develop a bioengineered tear secretory system for such patients. This article describes the growth and physiological properties of purified rabbit lacrimal gland acinar cells (pLGACs) on several matrix protein-coated polymers such as silicone, collagen I, copolymers of poly-D,L-lactide-co-glycolide (PLGA; 85:15 and 50:50), poly-L-lactic acid (PLLA), and Thermanox plastic cell culture coverslips. Monolayers of acinar cells were established on all of the polymeric substrata. An assay of beta-hexosaminidase activity in the supernatant medium showed significant increases in protein secretion, following stimulation with 100 microM carbachol on matrix protein-coated and uncoated polymers such as silicone, PLGA 85:15, and PLLA. Our study demonstrates that PLLA supported the morphological and physiological properties of purified rabbit lacrimal gland epithelial cells more successfully than the others.

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PubMed2006

Esterified estrogens combined with methyltestosterone raise intraocular pressure in postmenopausal women.

PURPOSE: To investigate the effect of esterified estrogens combined with methyltestosterone (EECM) (Estratest, Solvay, Pharmaceuticals, Inc, Baudette, Minnesota, USA) on intraocular pressure (IOP) in postmenopausal women. DESIGN: Observational case series. METHODS: The IOP of 13 consecutive postmenopausal women with dry eye syndrome were recorded before and during EECM therapy (1.25 mg of esterified estrogens and 2.5 mg of methyltestosterone for several months). RESULTS: The mean IOP increased from a baseline of 15.0 mm Hg before treatment to 18.2 mm Hg on EECM therapy (P < .0001) after a median duration of 11.3 months (range, 0.9 to 24 months). The increase in IOP was statistically significant at the 0.05 level of significance within three months and continued over 12 months. Two patients whose pressures increased (>4 mm Hg) returned to baseline levels after EECM was discontinued. CONCLUSIONS: Esterified estrogens combined with methyltestosterone produce a clinically significant increase in IOP in postmenopausal women with dry eye syndrome.

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PubMed2006

Tissue engineering: current and future approaches to ocular surface reconstruction.

Although cells have been cultured outside the body for many years, research has only recently begun to develop complex three-dimensional tissue constructs that will, ideally, mature into fully functional tissues and organs. Tissue engineering is an emerging field in the area of biotechnology that combines the principles and methods of life sciences with those of engineering for the purpose of regenerating, repairing, or replacing diseased tissues. In this review, we describe the recent advances and current development of tissue engineering approaches as related to the ocular surface system, which comprises the three main integrated tissue units: conjunctiva, cornea and lacrimal glands.

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PubMed2006

Dysfunctional tear syndrome: a Delphi approach to treatment recommendations.

PURPOSE: To develop current treatment recommendations for dry eye disease from consensus of expert advice. METHODS: Of 25 preselected international specialists on dry eye, 17 agreed to participate in a modified, 2-round Delphi panel approach. Based on available literature and standards of care, a survey was presented to each panelist. A two-thirds majority was used for consensus building from responses obtained. Treatment algorithms were created. Treatment recommendations for different types and severity levels of dry eye disease were the main outcome. RESULTS: A new term for dry eye disease was proposed: dysfunctional tear syndrome (DTS). Treatment recommendations were based primarily on patient symptoms and signs. Available diagnostic tests were considered of secondary importance in guiding therapy. Development of algorithms was based on the presence or absence of lid margin disease and disturbances of tear distribution and clearance. Disease severity was considered the most important factor for treatment decision-making and was categorized into 4 levels. Severity was assessed on the basis of tear substitute requirements, symptoms of ocular discomfort, and visual disturbance. Clinical signs present in lids, tear film, conjunctiva, and cornea were also used for categorization of severity. Consensus was reached on treatment algorithms for DTS with and without concurrent lid disease. CONCLUSION: Panelist opinion relied on symptoms and signs (not tests) for selection of treatment strategies. Therapy is chosen to match disease severity and presence versus absence of lid margin disease or tear distribution and clearance disturbances.

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PubMed2005

Combined esterified estrogen and methyltestosterone treatment for dry eye syndrome in postmenopausal women.

PURPOSE: To determine whether systemic replacement with combined esterified estrogen (EE) and methyltestosterone (MT) (EE + MT) would reduce symptoms and promote clinical improvement in postmenopausal women with dry eye syndrome (DES). DESIGN: Retrospective, noncomparative, interventional case series. METHODS: Investigators reviewed the charts of 11 postmenopausal women treated within the last 3 years with EE + MT. RESULTS: The mean patient age was 65.2 years (standard deviation [SD] 11.4, range 48-84 years). The mean treatment duration was 12.2 months (SD 6.2 months, range 4-24 months). Ten (91%) of 11 patients reported improvement in dry eye symptoms while receiving treatment. For these 10, relief occurred after an average of 4.1 months of treatment (SD 3.2, range, 1-9 months). CONCLUSIONS: Treatment with EE + MT may be efficacious for DES of various etiologies. A randomized placebo-controlled trial is planned to further evaluate these encouraging findings.

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