Publications by authors named "Irene Cho"

7 Publications

  • Page 1 of 1

A combinatorial cis-regulatory logic restricts color-sensing Rhodopsins to specific photoreceptor subsets in Drosophila.

PLoS Genet 2021 Jun 23;17(6):e1009613. Epub 2021 Jun 23.

Department of Biology, Integrated Sciences Complex, University of Massachusetts Boston, Boston, Massachusetts, United States of America.

Color vision in Drosophila melanogaster is based on the expression of five different color-sensing Rhodopsin proteins in distinct subtypes of photoreceptor neurons. Promoter regions of less than 300 base pairs are sufficient to reproduce the unique, photoreceptor subtype-specific rhodopsin expression patterns. The underlying cis-regulatory logic remains poorly understood, but it has been proposed that the rhodopsin promoters have a bipartite structure: the distal promoter region directs the highly restricted expression in a specific photoreceptor subtype, while the proximal core promoter region provides general activation in all photoreceptors. Here, we investigate whether the rhodopsin promoters exhibit a strict specialization of their distal (subtype specificity) and proximal (general activation) promoter regions, or if both promoter regions contribute to generating the photoreceptor subtype-specific expression pattern. To distinguish between these two models, we analyze the expression patterns of a set of hybrid promoters that combine the distal promoter region of one rhodopsin with the proximal core promoter region of another rhodopsin. We find that the function of the proximal core promoter regions extends beyond providing general activation: these regions play a previously underappreciated role in generating the non-overlapping expression patterns of the different rhodopsins. Therefore, cis-regulatory motifs in both the distal and the proximal core promoter regions recruit transcription factors that generate the unique rhodopsin patterns in a combinatorial manner. We compare this combinatorial regulatory logic to the regulatory logic of olfactory receptor genes and discuss potential implications for the evolution of rhodopsins.
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June 2021

Waste production from phacoemulsification surgery.

J Cataract Refract Surg 2020 02;46(2):215-221

From the Department of Ophthalmology, Miri Hospital, Ministry of Health, Sarawak, Malaysia.

Purpose: To determine the amount of waste produced from phacoemulsification surgeries and ways to curtail the problem.

Setting: Miri Hospital, Sarawak, Malaysia.

Design: Prospective study.

Methods: Phacoemulsification surgery cases were included in this study; nonphacoemulsification surgeries were excluded. The waste was subdivided into 3 main categories, general waste, clinical waste, and sharps. The waste produced by ophthalmologists and trainees was accounted for separately. The mean weight of waste per case was obtained by dividing the total weight of waste produced with the total number of cases.

Results: The total waste produced from a total of 203 cases of phacoemulsification surgeries was 167.965 kg, of which, 95.063 kg (56.6%) were clinical waste, 63.197 kg (37.6%) were general waste, and 9.705 kg (5.8%) were sharps; 32.193 kg (50.9%) out of the general waste pool were recyclable waste products. The mean waste production per case of phacoemulsification surgery for an ophthalmologist was 0.814 kg, 1.086 kg per case for a trainee. A case of phacoemulsification surgery would produce 0.282 kg of carbon dioxide equivalents in the setup based on the recyclable general waste.

Conclusions: The average waste produced per case of phacoemulsification surgery in Miri Hospital was 0.827 kg. After excluding the recyclable material, the average waste produced per case was 0.669 kg. Following the 3 R's principles (reduce, reuse, and recycle) in the handling of waste production might reduce environmental impact.
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February 2020

Spectrum of Microbial Keratitis Encountered in the Tropics.

Eye Contact Lens 2020 Jan;46(1):17-23

Department of Ophthalmology, Miri Hospital, Sarawak, Malaysia.

Purpose: To report the predisposing factors, microorganisms, antibiotic sensitivity associated with bacterial keratitis, and treatment outcomes in Miri, Borneo which has a tropical climate.

Methods: This is a retrospective study on patients presenting with microbial keratitis in Miri, Sarawak, Borneo over a 7-year period from January 1, 2010 until December 31, 2016. Demographic data, predisposing factors, culture and sensitivity results together with treatment outcomes were studied.

Results: There were a total of 221 cases treated as microbial keratitis with a peak age group of 21 to 30 years. The predisposing factors were trauma (49.3%), improper contact lens usage (29.1%), ocular surface diseases (5.9%), ocular surgeries (0.9%), drugs (1.8%), and other factors (19.0%). Occupational injuries among oil palm plantation workers was the leading cause within the trauma cohort (28.8%). Corneal scraping was performed in 189 cases, 61.4% of them yielded positive cultures. The cultures demonstrated that 49.1% were of bacterial origin, 46.6% were fungal, and 4.3% showed mixed growth. The most common bacteria isolated was Pseudomonas aeruginosa, which was sensitive toward ceftazidime and gentamicin antibiotics. One hundred ninety-two cases (86.9%) were treated with purely topical medication, whereas 29 cases (13.1%) required further interventions.

Conclusion: The commonest predisposing factor for microbial keratitis was trauma. With the nearby oil palm industries, we report a corresponding increase of incidence in fungal keratitis at our center. Culture and sensitivity reports from corneal scrapings are essential in treatment guidance; however, more than a third of the microbial keratitis cases studied were culture-negative. The organisms cultured reflect the profile expected in tropical climates. Fortunately, there was no increase in resistance rates observed for the commonly used antibiotics.
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January 2020

Effect of lipid-based dry eye supplements on the tear film in wearers of eye cosmetics.

Cont Lens Anterior Eye 2017 Aug 11;40(4):236-241. Epub 2017 Mar 11.

Department of Ophthalmology, New Zealand National Eye Centre, The University of Auckland, New Zealand. Electronic address:

Purpose: To compare the effects on tear film parameters and contamination in cosmetic eyeliner wearers, after single application of two lipid-based dry eye treatments: a lipid-containing lubricant eye drop and a phospholipid liposomal spray.

Methods: Fifty participants were enrolled in a prospective, randomised, paired-eye, investigator-masked trial. Pencil eyeliner (Body Shop Crayon Eye Definer) was applied to the upper eyelid periocular skin of both eyes, anterior to the lash line. Baseline tear film quality was assessed fifteen minutes after eyeliner application. A lubricant drop (Systane Balance) was then applied to one eye (randomised), and liposomal spray (Tears Again) to the contralateral eye. Tear film contamination, lipid layer grade, non-invasive tear film break-up time and tear evaporation rate were evaluated fifteen minutes post-treatment and compared to pre-treatment values.

Results: Pre-treatment measurements did not differ between eyes assigned to lubricant drop and liposomal spray. Tear film contamination was observed in a greater proportion of eyes following both treatments (both p<0.05), with no significant difference between treatments (p=0.41). Both treatments improved lipid layer thickness (both p≤0.01), but effected no significant change in non-invasive tear film break-up time or tear evaporation rate (all p>0.05). Changes in tear film parameters did not differ between treatments (all p>0.05).

Conclusions: Both the lipid-containing lubricant eye drop and phospholipid liposomal spray result in clinically apparent tear film contamination in eyeliner cosmetic wearers. Although both treatments effected an increase in lipid layer thickness, neither displayed clinical efficacy in improving tear film stability.
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August 2017

Donor lymphocyte count and thymic activity predict lymphocyte recovery and outcomes after matched-sibling hematopoietic stem cell transplant.

Haematologica 2013 Mar 12;98(3):346-52. Epub 2012 Oct 12.

Allogeneic Stem Cell Transplantation Section, Hematology Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA.

Delayed immune recovery is a characteristic feature of allogeneic hematopoietic stem cell transplantation in adult recipients. Although recipient thymic T-cell neogenesis contributes to T-cell regeneration after transplantation, thymic recovery in the transplant recipient decreases with increasing age, and is diminished by intensive preconditioning regimens and graft-versus-host disease. In adult recipients, most events that determine transplant success or failure occur during the period when the majority of circulating T cells is derived from the donor's post thymic T-cell repertoire. As a result, the make-up of the donor lymphocyte compartment may strongly influence immune recovery and transplant outcomes. The aim of this study was to examine donor lymphocyte counts in a series of patients undergoing an allogeneic hematopoietic stem cell transplant to identify the potential contribution of donor regulatory and conventional T lymphocyte populations to immune recovery and transplant outcomes. We examined donor lymphocyte subset counts in relation to post-transplant lymphocyte recovery and transplant events in 220 consecutive myeloablative, T-cell-depleted, HLA-identical sibling hematopoietic stem cell transplant recipients with hematologic malignancies. In a multivariate analysis, absolute numbers of donor CD4(+) recent thymic emigrants were associated with overall survival (P=0.032). The donors' absolute lymphocyte count and thymic production of regulatory T cells were both associated with extensive chronic graft-versus-host disease (P=0.002 and P=0.022, respectively). In conclusion, these results identify donor immune characteristics that are associated with lymphocyte recovery, extensive chronic graft-versus-host disease, and survival in the recipient following allogeneic hematopoietic stem cell transplantation. The study reported here was performed using peripheral blood samples drawn from donors and patients enrolled in the trials NCT00001623, NCT00001873, NCT00353860, NCT00066300, NCT00079391, and NCT00398346.
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March 2013

Age- and diet-specific effects of variation at S6 kinase on life history, metabolic, and immune response traits in Drosophila melanogaster.

DNA Cell Biol 2010 Sep;29(9):473-85

Department of Biological Sciences, University of Maryland Baltimore County , Baltimore, MD 21250, USA.

Life history theory hypothesizes that genetically based variation in life history traits results from alleles that alter age-specific patterns of energy allocation among the competing demands of reproduction, storage, and maintenance. Despite the important role that alleles with age-specific effects must play in life history evolution, few naturally occurring alleles with age-specific effects on life history traits have been identified. A recent mapping study identified S6 kinase (S6k) as a candidate gene affecting lipid storage in Drosophila. S6k is in the target of rapamycin pathway, which regulates cell growth in response to nutrient availability and has also been implicated to influence many life history traits from fecundity to life span. In this article, we used quantitative complementation tests to examine the effect of allelic variation at S6k on a range of phenotypes associated with metabolism and fitness in an age-, diet-, and sex-specific manner. We found that alleles of S6k have pleiotropic effects on total protein levels, glycogen storage, life span, and the immune response and demonstrate that these allelic effects are age, diet, and sex specific. As many of the genes in the target of rapamycin pathway are evolutionarily conserved, our data suggest that genes in this pathway could play a pivotal role in life history evolution in a wide range of taxa.
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September 2010

Prevalence and clinical outcome of inpatient hyperglycemia in a community pediatric hospital.

J Hosp Med 2008 May;3(3):212-7

Department of Medicine, Division of Endocrinology, Emory University School of Medicine, Atlanta, Georgia, USA.

Background: Inpatient hyperglycemia in adult patients with and without a history of diabetes is a predictor of poor clinical outcome. No previous studies, however, have examined the association of hyperglycemia and clinical outcome in children admitted to a community pediatric hospital.

Methods: The study was a retrospective observational cohort of pediatric patients admitted to a community children's hospital from January 2004 to August 2004. Medical records of 903 consecutive children admitted to critical and non-critical care areas were reviewed. Of them, 342 patients (38%) had no blood glucose measurements during their hospital stay. In the remaining patients, we determined the prevalence of hyperglycemia and examined the association of hyperglycemia with clinical outcome.

Results: A total of 406 patients (75%) had an admission blood glucose < or =120 mg/dL (mean +/- SEM 98 +/- 1 mg/dL), 103 children (19%) had an admission blood glucose level of 121-179 mg/dL (mean 143 +/- 2 mg/dL), and 32 patients (5.9%) had a blood glucose level > or =180 mg/dL (mean 260 +/- 18 mg/dL). Seventeen patients (13%) had a known history of diabetes prior to admission. Children with hyperglycemia were more likely to be admitted to the ICU (P < .001) and had a longer length of ICU stay (P < .001), but admission hyperglycemia was not associated with longer hospital stay or higher hospital mortality.

Conclusions: Hyperglycemia is present in one-fourth of children admitted to the hospital, most of them without a history of diabetes prior to admission. Hyperglycemia was associated with a greater need for ICU care and longer ICU stay but not with increased in-hospital mortality.
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May 2008