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Biomedical subjects

G Woo

Publications and source records attributed to G Woo.

9 recordsLinked to original sources
PubMed1999

The intermolecular disulfide bridge of human glial cell line-derived neurotrophic factor: its selective reduction and biological activity of the modified protein.

Recombinant human glial cell line-derived neurotrophic factor has been implicated to have therapeutic potential in the treatment of neurodegenerative diseases. The mature protein is a single polypeptide of 134 amino acid residues and functions as a disulfide-linked dimer. Reduction of the protein with dithiothreitol at pH 7.0 and in the absence of denaturant showed that the single intermolecular cystine bridge was reduced preferentially. Direct alkylation of the generated free sulfhydryl group using iodoacetamide or iodoacetate without denaturant was incomplete. Unfolding the protein in 6 M guanidine hydrochloride prior to the modification showed rapid disulfide scrambling. However, the sulfhydryl-modifying reagent N-ethylmaleimide was able to label quantitatively the free cysteinyl residue in the absence of any added chaotropic agent. By a combination of peptide mapping, Edman degradation, and mass spectrometric analysis, the labeled residue was identified to be Cys101, hence verifying the location of the intermolecular disulfide bond. The modified protein behaved as a noncovalent dimer when chromatographed through a Superdex 75 column under nondenaturing conditions and was comparable in biological activity to an unmodified control sample. The results therefore indicate that the intermolecular disulfide bridge of the protein is not essential for its biological function.

Alkylation↗
PubMed1999

Ethnicity and social support during pregnancy.

Data from two multi-ethnic prospective studies of African American, Latina, and non-Hispanic White pregnant women were used to examine the influence of contextual factors on social support processes during pregnancy. Multiple types of support (perceived support, received support, support satisfaction, network support) and sources of support (baby's father, family, friends) were assessed. The role of ethnicity in social support was examined after controlling for the contribution of related contextual factors (SES, marital status, age, parity, employment) to these processes. The impact of ethnicity and related contextual factors differed across sources of social support. Ethnic differences in support from family and friends, but not from the baby's father, emerged. However, marital status was a consistent predictor of support from the baby's father, and SES was a consistent predictor of support from friends. Overall, the findings of two studies suggest that although ethnicity is associated with support from friends and family, other contextual factors, such as marital status and SES, influence support processes during pregnancy.

Acculturation↗
PubMed1990

The influence of frequent ingestion of acids in the diet on treatment for dentin sensitivity.

For many patients with severe and persistent pain from dentin sensitivity, therapeutic interventions often produce unsatisfactory results. Eighteen patients with persistent dentin sensitivity following a two-month clinical trial of a desensitizing dentifrice and a two-week treatment of four applications of a topical fluoride varnish participated in post-hoc evaluation of the association between the frequency of acid ingestions in the diet and the persistence of pain. A specific food frequency assessment was performed and tested for association against longitudinal, clinical and subjective patient assessments. There was a negative association (r = 0.49) between the frequency of ingestion of specific acid foods and beverages and the persistence of dentin sensitivity. Findings suggest that nutritional counselling should be part of the treatment offered for patients with these problems.

Acids↗
PubMed1989

A review of the prevalence and causes of myopia.

In this study, we reviewed the prevalence of myopia by country. Different types of myopia are elaborated and the causes of myopia are presented. It appears that the origin of myopia is due to both environmental and genetic factors.

Animals↗
PubMed1978

Vision through cataracts.

Contrast thresholds for a range of different spatial frequencies were compared with "acuity" tests for 10 subjects with uniocular senile cataract. The results indicate that the magnitude and extent of the intra-resolution limit abnormality vary dramatically in cataract subjects and that, for some subjects, vision is abnormal for objects of all sizes. This finding indicates that the present acuity evaluation of vision with cataracts is inadequate because, in some cases, it grossly overestimates the nature of the visual world of the cataract patient.

Aged↗
PubMedDate not supplied

Excimer photorefractive keratectomy after undercorrected radial keratotomy.

Radial keratotomy has been used for the treatment of myopia since 1979. Until recently, patients with undercorrected myopia had recourse only to repeated keratotomy. Now patients undercorrected after two or more radial keratotomy procedures can be treated with the excimer laser to reduce the residual myopia. Nineteen eyes of 17 patients with undercorrected myopia after repeated radial had excimer photoradial keratectomy performed. The mean residual spherical equivalent refractive error after radial keratotomy was -2.74 +/- 1.06 diopters (D). This was further reduced after PRK. Final uncorrected visual acuity ranged from 20/20 to 20/70. Excimer laser PRK offers a safe and more controlled method of treating residual after radial keratotomy.

Adolescent↗