Search PubMed⌕ Search

Biomedical subjects

C Ahn

Publications and source records attributed to C Ahn.

At least 73 records · Page 4Linked to original sources
PubMed2000

Increased plasma homocysteine is an independent predictor of new atherothrombotic brain infarction in older persons.

A prospective study investigated the association of plasma homocysteine and other risk factors with the incidence of atherothrombotic brain infarction (ABI) at 31 +/- 9 month follow-up in 153 men and 347 women (mean age 81 +/- 9 years, median age 82). The stepwise Cox regression model showed that significant independent predictors of new ABI in older persons were age (risk ratio 1.060 for each 1-year increase of age), plasma homocysteine (risk ratio 1.079 for each 1 micromol/L increase), prior ABI infarction (risk ratio 3.282), current cigarette smoking (risk ratio 2.687), hypertension (risk ratio 2.965), and diabetes mellitus (risk ratio 2.015).

Aged↗
PubMed2000

Increased plasma homocysteine is an independent predictor of new coronary events in older persons.

A prospective study investigated the association of plasma homocysteine and other risk factors with the incidence of new coronary events at 31 +/- 9 month follow-up in 153 men and 347 women, mean age 81 +/- 9 years. The stepwise Cox regression model showed that significant independent predictors of new coronary events in older persons were age (risk ratio 1.041), plasma homocysteine (risk ratio 1.073), current cigarette smoking (risk ratio 2.524), hypertension (risk ratio 2.032), diabetes mellitus (risk ratio 2.022), serum total cholesterol (risk ratio 1.013), serum high-density lipoprotein cholesterol (risk ratio 0.925), and serum triglycerides (risk ratio 1.004).

Aged↗
PubMed2000

Association of mitral annular calcium with prior thromboembolic stroke in older White, African-American, and Hispanic men and women.

Prior thromboembolic stroke was present in 57 of 188 white men (30%) with mitral annular calcium (MAC) and in 62 of 303 white men (20%) without MAC, in 42 of 65 African-American men (65%) with MAC and in 50 of 123 African-American men (41%) without MAC, and in 13 of 27 Hispanic men (48%) with MAC and in 21 of 58 Hispanic (36%) without MAC. Prior thromboembolic stroke was present in 164 of 614 white women (27%) with MAC and in 85 of 516 white women (16%) without MAC, in 111 of 193 African-American women (58%) with MAC and in 77 of 225 African-American women (34%) without MAC, and in 36 of 69 Hispanic women (52%) with MAC, and in 17 of 58 Hispanic women (29%) without MAC.

Aged↗
PubMed2000

Association of diabetes mellitus using old and new diagnostic criteria with incidence of new coronary events in older men and women.

A prospective study investigated in 952 men (mean age 79 years) and in 2,014 women (mean age 81 years), the association of diabetes mellitus using the old and new diagnostic criteria with the incidence of new coronary events. At 40-month follow-up for men and 44-month follow-up for women, whether the old or the new criteria for diagnosing diabetes mellitus were used, diabetes mellitus was significantly associated with the incidence of new coronary events (p <0.0001) in older men and women.

Aged↗
PubMed2000

Accuracy of clinical judgment in neonatal jaundice.

CONTEXT: Recommendations for management of jaundice in newborns presume thatjaundice is a reliable clinical finding and that the pattern and intensity of jaundice reflects the degree of elevation of the serum bilirubin level. OBJECTIVES: To determine whether experienced observers agree in describing the extent of jaundice and to evaluate the reliability of visual assessment as an indication for the measurement of serum bilirubin levels. DESIGN: Comparison of independent judgments of the extent of jaundice between examiners and with actual serum bilirubin measurements. SETTING: Well-newborn nursery in an urban public hospital. PARTICIPANTS: A convenience sample of 122 healthy term newborns whose bilirubin concentration was measured in the course of standard newborn care. Observers were experienced pediatric nurse practitioners, pediatric house staff, and pediatric attending physicians. RESULTS: Agreement was moderately good for whether an infant's skin was darkly pigmented (K = 0.56). However, agreement between observers regarding the presence of jaundice at each specific body site was poor (0%-23% agreement beyond chance); correlation between estimated bilirubin concentrations was similarly poor (Pearson correlation coefficient, 0.37). Correlation between estimated and actual bilirubin values was slightly better (Pearson correlation coefficient, 0.43-0.54). CONCLUSIONS: Clinical examination with visual assessment for jaundice in newborns is neither reliable nor accurate. The decision to perform serum bilirubin testing should be based on additional factors.

Bilirubin↗
PubMed2000

Autoantibodies to fibrillin 1 in systemic sclerosis: ethnic differences in antigen recognition and lack of correlation with specific clinical features or HLA alleles.

OBJECTIVE: We previously reported the presence of autoantibodies to the extracellular matrix protein, fibrillin 1, in sera from patients with systemic sclerosis (SSc). These autoantibodies appeared to be highly disease-specific but had significantly different frequencies among ethnic groups. The aims of this study were 3-fold: 1) to determine whether sera from SSc patients of different ethnic backgrounds recognized different antigenic epitopes of fibrillin 1, 2) to determine whether sera from patients with polymyositis/dermatomyositis (PM/DM) with or without interstitial lung disease (ILD) also produced these antibodies, and 3) to determine any correlation of anti-fibrillin 1 antibodies with specific clinical features of SSc, other autoantibodies, or HLA class II alleles in a prospectively studied cohort of SSc patients with early (<5 years' duration) disease (the Genetics versus Environment In Scleroderma Outcome Study [GENISOS] cohort). METHODS: Three recombinant peptides accounting for the N-terminal end, proline-rich C region, and epidermal growth factor-like calcium-binding (EGF-cb) domains of fibrillin 1 were used in a radioimmunoassay to screen sera from a large group of SSc and PM/DM patients and ethnically matched controls. RESULTS: The majority of Choctaw American Indians, Japanese, and African Americans with SSc produced IgM and/or IgG autoantibodies to one or more recombinant fibrillin 1 proteins, while <50% of Caucasians with SSc showed seroreactivity. There were striking ethnic differences in fibrillin 1 antigenic epitope recognition among these ethnic groups. African American SSc sera recognized primarily the N-terminal end, and Caucasian sera mostly recognized the EGF-cb repeats and the proline-rich C region. In contrast, most Choctaw American Indian and Japanese SSc sera appeared to recognize 2 or 3 epitopes, respectively. PM/DM patient sera did not recognize any of the fibrillin 1 epitopes regardless of the presence of ILD. In the prospective, multiethnic GENISOS cohort, the presence of anti-fibrillin 1 antibodies did not correlate with any major clinical manifestations, other autoantibodies, or HLA class II alleles. CONCLUSION: There are striking ethnic differences in antigenic epitope specificity of anti-fibrillin 1 antibodies in patients with SSc, and the majority of SSc patients, except for Caucasians, produce antibodies to fibrillin 1. The antifibrillin response thus far remains specific for scleroderma syndromes, but it does not correlate with any major clinical features, other autoantibodies, or HLA class II alleles.

Alleles↗
PubMed2000

A comparison of laparoscopic Nissen fundoplication and Rossetti's modification in 239 patients.

BACKGROUND: Laparoscopic Nissen fundoplication and the Rossetti modification represent two different surgical approaches to resolving gastroesophageal reflux disease (GERD). Concerns have arisen that the Rossetti modification results in increased postoperative dysphagia. In this study, we compared a group of patients who underwent a laparoscopic Nissen fundoplication with a group who had undergone the Rossetti modification to determine if there was a significant difference in postoperative dysphagia. Additionally, we wanted to confirm that the Nissen procedure performed laparoscopically could resolve GERD as successfully as the Rossetti modification, with no difference in operative complications. METHODS: We prospectively collected data on 101 patients who underwent laparoscopic Nissen fundoplication and compared outcomes with those of 138 patients who had undergone the laparoscopic Rossetti modification in a previous series. RESULTS: All patients experienced resolution of reflux symptoms. No statistically significant differences were found between the groups in terms of intraoperative or postoperative complications, conversions to open procedure, or length of hospitalization. Paradoxically, there was a significant difference in operating time between the Rossetti and the Nissen groups (70.6 min vs 45.6 min, p = 0.006). Postoperative dysphagia requiring dilation was significantly higher in the Rossetti group (21.7% vs 8.9%, p = 0.008). However, there was a significantly higher percentage of patients in the Rossetti group who had had esophagitis preoperatively (95.7% vs 86.1%, p = 0.009), although the proportion of patients having Barrett's esophagus was higher in the Nissen group (9.4% vs 24.8%, p = 0.001). CONCLUSIONS: Both approaches resolved reflux symptoms without significant differences in complications, conversions, or length of stay. Preoperative differences between groups, as well as the method of sequentially comparing the two different procedures, prevent us from attributing greater postoperative dysphagia in the Rossetti group solely to the choice of surgical approach. Prospective randomized studies are needed to control for variables, such as surgical team experience and patient differences.

Adolescent↗
PubMed2000

Comparison of visual results in initial and re-treatment laser in situ keratomileusis procedures for myopia and astigmatism.

PURPOSE: To report the results of initial and re-treatment laser in situ keratomileusis procedures for myopia and astigmatism. METHODS: A total of 1161 consecutive inital and retreatment laser in situ keratomileusis procedures in 697 patients performed between September 19, 1996, and June 20, 1998, were retrospectively analyzed. Baseline and postoperative best spectacle-corrected visual acuity, uncorrected visual acuity, spherical and cylindrical refractions, computerized video keratography, and biomicroscopy were measured or performed on each eye. RESULTS: Of 1,071 eyes, 900 (84%) underwent a single-laser in situ keratomileusis procedure, and 171 of 1,071 eyes (16%) underwent one or two re-treatment procedures. The preoperative mean +/- SD spherical equivalent was -5.09 +/- 3.15 diopters (range, -0.75 to -14.38 diopters) and the cylinder was 0.97 +/- 1.09 diopters (range, 0.00 to 3.25 diopters) in the group that underwent a single laser in situ keratomileusis treatment. The preoperative mean +/- SD spherical equivalent was -6.26 +/- 3.04 diopters (range, -1.75 to -12.88 diopters) and the cylinder was 1.53 +/- 1.11 diopters (range, 0.00 to 3.50 diopters) in the group that underwent re-treatment. Before re-treatment, 110 eyes (64.3%) in the group that underwent re-treatment achieved 20/40 or better uncorrected visual acuity and 23 eyes (13.5%) achieved 20/25 or better. Three months after re-treatment, 155 eyes (90.6%) achieved 20/40 or better, and 80 eyes (46.8%) achieved 20/25 or better. In the single-procedure group, uncorrected visual acuity at 3 months revealed 20/40 vision or better in 856 eyes (95.1%) and 20/25 vision or better in 572 eyes (63.6%). In this study group, 23.6% of eyes with a preoperative spherical equivalent greater than -6.0 diopters underwent re-treatment compared with 11.8% of eyes with a preoperative spherical equivalent of -6.0 diopters or less. CONCLUSIONS: Laser in situ keratomileusis appears to be an effective procedure for mild, moderate, and severe myopia. In eyes with residual refractive error, re-treatment laser in situ keratomileusis procedures can result in good visual outcomes.

Astigmatism↗
PubMed2000

Novel mutations of the PKD1 gene in Korean patients with autosomal dominant polycystic kidney disease.

The gene for the most common form of autosomal dominant polycystic kidney disease (ADPKD), PKD1, has recently been characterized and shown to encode an integral membrane protein, polycystin-1, which is involved in cell-cell and cell-matrix interactions. Until now, approximately 30 mutations of the 3' single copy region of the PKD1 gene have been reported in European and American populations. However, there is no report of mutations in Asian populations. Using the polymerase chain reaction and single-strand conformation polymorphism (SSCP) analysis, 91 Korean patients with ADPKD were screened for mutation in the 3' single copy region of the PKD1 gene. As a result, we have identified and characterized six mutations: three frameshift mutations (11548del8bp, 11674insG and 12722delT), a nonsense mutation (Q4010X), and two missense mutations (R3752W and D3814N). Five mutations except for Q4010X are reported here for the first time. Our findings also indicate that many different mutations are likely to be responsible for ADPKD in the Korean population. The detection of additional disease-causing PKD1 mutations will help in identifying the location of the important functional regions of polycystin-1 and help us to better understand the pathophysiology of ADPKD.

Frameshift Mutation↗
PubMed2000

Thirteen novel mutations of the replicated region of PKD1 in an Asian population.

BACKGROUND: Mutations of PKD1 are thought to account for approximately 85% of all mutations in autosomal dominant polycystic kidney disease (ADPKD). The search for PKD1 mutations has been hindered by both its large size and complicated genomic structure. To date, few mutations that affect the replicated segment of PKD1 have been described, and virtually all have been reported in Caucasian patients. METHODS: In the present study, we have used a long-range polymerase chain reaction (PCR)-based strategy previously developed by our laboratory to analyze exons in the replicated region of PKD1 in a population of 41 unrelated Thai and 6 unrelated Korean families with ADPKD. We have amplified approximately 3.5 and approximately 5 kb PKD1 gene-specific fragments (5'MR and 5'LR) containing exons 13 to 15 and 15 to 21 and performed single-stand conformation analysis (SSCA) on nested PCR products. RESULTS: Nine novel pathogenic mutations were detected, including six nonsense and three frameshift mutations. One of the deletions was shown to be a de novo mutation. Four potentially pathogenic variants, including one 3 bp insertion and three missense mutations, were also discovered. Two of the nonconservative amino acid substitutions were predicted to disrupt the three-dimensional structure of the PKD repeats. In addition, six polymorphisms, including two missense and four silent nucleotide substitutions, were identified. Approximately 25% of both the pathogenic and normal variants were found to be present in at least one of the homologous loci. CONCLUSION: To our knowledge, this is the first report of mutation analysis of the replicated region of PKD1 in a non-Caucasian population. The methods used in this study are widely applicable and can be used to characterize PKD1 in a number of ethnic groups using DNA samples prepared using standard techniques. Our data suggest that gene conversion may play a significant role in producing variability of the PKD1 sequence in this population. The identification of additional mutations will help guide the study of polycystin-1 and better help us to understand the pathophysiology of this common disease.

Amino Acid Sequence↗
PubMed2000

Issues in use of SAS PROC.MIXED to test the significance of treatment effects in controlled clinical trials.

A project that originated with the aim of documenting the implications of dropouts for tests of significance based on general linear mixed model procedures resulted in recognition of problems in the use of SAS PROC.MIXED for this purpose. In responding to suggestions and criticisms, we have further analyzed simulated clinical trial data with realistic autoregressive structure, using alternative error model formulations, different approaches to the use of covariates to model dropout patterns, and different ways to include the critical time variable in the mixed model. Results emphasize the sensitivity of the PROC.MIXED tests of significance for GROUP and TIME x GROUP equal slopes hypothesis to less than optimal modeling of the error covariance structure. Even with the authoritatively recommended best available modeling of the error structure, model formulations that made use of the REPEATED statement did not maintain conservative test sizes when covariates were required to model dropout data patterns. Random coefficients models that employed the RANDOM statement did permit appropriate covariate controls, but the tests of significance for treatment effects were lacking in power. After examining a variety of alternative PROC.MIXED model formulations, it is concluded that none provided both Type I error protection and power comparable to that of simple two-stage analysis of covariance (ANCOVA) procedures for confirming the presence of true treatment effects in controlled clinical trials. Other issues examined in this article concern treating baseline scores as both covariate and initial repeated measurement to which a linear means model is fitted, failure to take advantage of the regression of repeated measurements on time in modeling time as an unordered categorical variable, and fitting linear regression models to nonlinear response patterns.

Algorithms↗
PubMed2000

Risk factors for coronary artery disease in old persons in an academic hospital-based geriatrics practice.

BACKGROUND: Risk factors for coronary artery disease (CAD) in old men and women include age, cigarette smoking, hypertension, diabetes mellitus, dyslipidemia, and obesity. OBJECTIVE: To investigate the association of risk factors with prevalence of CAD. METHODS: We performed a retrospective analysis of charts for all old persons seen during the period from 1 January 1998 through 15 June 1999 at an academic hospital-based geriatric practice to investigate associations of risk factors with prevalence of CAD among old persons. We studied 467 men, mean age 80 +/- 8 years, and 1444 women, mean age 81 +/- 8 years. RESULTS: CAD was present in 201 of 467 men (43%) and in 473 of 1444 women (33%; P < 0.0001). Risk factors for CAD according to univariate analysis were age (P < 0.0001 for women), cigarette smoking (P < 0.0001 for men and women), hypertension (P < 0.0001 for men and women), diabetes mellitus (P < 0.0001 for men and women), obesity (P < 0.0001 for men and women), and serum levels of total cholesterol (P < 0.0001 for men and P = 0.0001 for women), low-density lipoprotein (LDL) cholesterol (P < 0.0001 for men and P = 0.001 for women), and high-density lipoprotein (HDL) cholesterol (inverse association; P = 0.0001 for men and women). Stepwise logistic regression analysis showed that significant independent risk factors for CAD were cigarette smoking (odds ratio 6.7 for men), hypertension (odds ratios 3.3 for men and 2.7 for women), and serum levels of HDL cholesterol (odds ratio 0.83 for men and women) and LDL cholesterol (odds ratios 1.10 for men and 1.09 for women). CONCLUSIONS: Significant independent risk associations with prevalence of CAD among old persons were found for cigarette smoking by men, hypertension in men and women, and serum levels of HDL cholesterol (inverse association) in men and women, and of LDL cholesterol in men and women.

Age Factors↗
PubMed2000

Risk factors for ischemic stroke in older persons in an academic hospital based geriatrics practice.

We performed a retrospective analysis of charts investigating risk factors for ischemic stroke in 467 men (mean age 80±8 years) and 1444 women (mean age 81±8 years) seen in an academic geriatrics practice. Ischemic stroke was present in 126 of 467 men (27%) and in 296 of 1444 women (20%) (p=0.003). Stepwise logistic regression analysis showed that significant independent risk factors for ischemic stroke were age (p=0.005 in men and 0.010 in women, odds ratio=1.04 in men and 1.03 in women); cigarette smoking (p=0.006, odds ratio=1.7 in women); hypertension (p<0.001 in men and women, odds ratio=4.6 in men and 3.9 in women); diabetes mellitus (p=0.018 in men and <0.001 in women, odds ratio=1.9 in men and 2.0 in women); serum low-density lipoprotein cholesterol (p<0.001 in men and women, odds ratio=1.02 in men and 1.01 in women); and serum high-density lipoprotein cholesterol (p<0.001, odds ratio=0.97 in women). Significant independent risk factors for ischemic stroke in both sexes were: age, hypertension, diabetes mellitus, and serum low-density cholesterol; and in older women: cigarette smoking and serum high-density lipoprotein cholesterol (inverse association). (c) 2000 by CHF, Inc.

Journal Article↗
PubMed2000

Prevalence of coronary artery disease, ischemic stroke, and symptomatic peripheral arterial disease and of associated risk factors in older men and women with and without diabetes mellitus.

The authors performed a retrospective analysis of the prevalence of coronary artery disease, ischemic stroke, and symptomatic peripheral arterial disease and of associated risk factors in 99 men (mean age 79±8 years) with diabetes mellitus vs. 368 men (mean age 81±8 years) without diabetes mellitus, and in 260 women (mean age 80±8 years) with diabetes mellitus vs. 1184 women (mean age 81±8 years) without diabetes mellitus. All patients were seen in an academic outpatient geriatrics practice. Diabetic men had a higher prevalence of coronary artery disease, ischemic stroke, and symptomatic peripheral arterial disease (p<0.0001); a higher prevalence of smoking (p=0.023), hypertension (p<0.0001), and obesity (p=0.0007); higher levels of serum total and low density lipoprotein cholesterol (p<0.0001) and triglycerides (p=0.003); and lower levels of serum high density lipoprotein cholesterol (p=0.0001) than men without diabetes mellitus. Diabetic women had a higher prevalence of coronary artery disease, ischemic stroke, and symptomatic peripheral arterial disease (p<0.0001); a higher prevalence of hypertension and obesity (p<0.0001); higher levels of serum total and low density lipoprotein cholesterol (p=0.0001) and triglycerides (p=0.005); and lower levels of serum high density lipoprotein cholesterol (p=0.0001) than women without diabetes mellitus. (c) 2000 by CHF, Inc.

Journal Article↗