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Biomedical subjects

Chul Ahn

Publications and source records attributed to Chul Ahn.

At least 19 recordsLinked to original sources
PubMed2024

The phosphatidylserine targeting antibody bavituximab plus pembrolizumab in unresectable hepatocellular carcinoma: a phase 2 trial.

Immune checkpoint inhibitors targeting PD-1/L1 have modest efficacy in hepatocellular carcinoma as single agents. Targeting membranous phosphatidylserine may induce pro-inflammatory and -immune stimulating effects that enhance immunotherapy activity. This hypothesis was tested in a single-arm phase 2 trial evaluating frontline bavituximab, a phosphatidylserine targeting antibody, plus pembrolizumab (anti-PD-1) in patients with unresectable hepatocellular carcinoma (NCT03519997). The primary endpoint was investigator-assessed objective response rate among evaluable patients, and secondary end points included progression-free survival, incidence of adverse events, overall survival, and duration of response. Among 28 evaluable patients, the confirmed response rate was 32.1%, which met the pre-specified endpoint, and the median progression-free survival was 6.3 months (95% CI, 1.3-11.3 months). Treatment related-adverse events of any grade occurred in 45.7% of patients, with grade 3 or greater adverse events in 14.3% of patients. Adverse events of any cause were observed in 33 patients (94.3%), with grade 3 or greater adverse events in 11 patients (31.4%). Prespecified exploratory analyses of baseline tumor specimens showed that a depletion of B cells, and the presence of fibrotic tissue and expression of immune checkpoints in stroma was associated with tumor response. These results suggest that targeting phosphatidylserine may lead to synergistic effects with PD-1 blockade without increasing toxicity rates, and future studies on this therapeutic strategy may be guided by biomarkers characterizing the pre-treatment tumor microenvironment.

Humans↗
PubMed2007

Voluntary childlessness is increased in women with inflammatory bowel disease.

BACKGROUND: The women's health aspect of inflammatory bowel disease (IBD) is a newer area of study; childbearing issues have received little attention despite the fact that IBD affects women predominantly during their childbearing years. The aim of this study was to better understand patients' considerations about pregnancy-related issues and to examine trends in childbearing so that physicians are able to better tailor their advice to IBD-specific concerns. METHODS: Data were gathered from specific questions in 3147 surveys mailed anonymously to all members of the Crohn's and Colitis Foundation of America (CCFA) Illinois Carol Fisher chapter. The subjects were provided a pre-addressed, pre-stamped return envelope and were instructed to return their completed surveys with no identifying information. Subjects were from the Illinois community. Females IBD patients were 15-44 of age and were members of the CCFA Illinois Carol Fisher chapter. RESULTS: In this study, 169 females age 15-44 years with IBD, 110 with Crohn's disease (CD) and 59 with ulcerative colitis (UC), were identified. Most subjects were white. IBD patients had a higher rate of voluntary childlessness (CD 18%, UC 14%) than the 6.2% seen in the general population (P = 0.001 for CD, P = 0.08 for UC). Women with UC had a lower rate of temporary childlessness (CD 28%, UC 13.6%) than the general population (33%) (P = NS and P < 0.0001 for UC). The rates of nonvoluntary childlessness in IBD were similar to the general population. Women with IBD also had fewer children than their state and national counterparts. The state of the patients' IBD, including those who had gone through a previous pregnancy with IBD, did not alter their resolve to have children. The educational level of our subjects was higher than the nationwide and statewide levels; 76% of the subjects used contraception before diagnosis of IBD, and 82% used it after diagnosis. The most common choices were oral contraception, barrier methods, and abstinence. This study was unable to compare the lifetime rates of complications of pregnancy with population-based controls because such data were unavailable. Furthermore, their findings in this study may not be generalized to all ethnic groups because our population was mostly white. CONCLUSIONS: Women with IBD had a higher rate of voluntary childlessness and fewer children than the general population. These observations are likely attributable to a higher educational achievement and to racial background of the patients rather than to IBD-related reasons. Although contraception use in patients with IBD was lower that in the general population, use was higher after the diagnosis of IBD than before the diagnosis. Contraceptive choices and adoption rates were similar to the general population. Women with CD were more affected by miscarriages after diagnosis with IBD than those with UC.

Adolescent↗
PubMed2006

Incidence of new stroke or new myocardial infarction or death in patients with severe carotid arterial disease treated with and without statins.

We investigated in 449 patients with severe carotid arterial disease, who did not undergo revascularization, the incidence of new stroke or new myocardial infarction (MI) or death in patients treated with statins (66%) and in patients not treated with lipid-lowering therapy (34%). Hypercholesterolemia was present in all of the 298 patients (100%) treated with statins and in 145 of 151 patients (96%) not treated with statins (p = 0.001). Follow-up was 26 +/- 18 months in patients treated with statins and 21 +/- 17 months in patients not treated with statins (p <0.0001). New stroke or new MI or death occurred in 45 of 298 patients (15%) treated with statins and in 102 of 151 patients (68%) not treated with statins (p <0.0001). Stepwise Cox regression analysis showed that significant independent prognostic factors for time to development of new stroke or new MI or death were use of statins (risk ratio 0.13, p <0.0001), smoking (risk ratio 1.45, p = 0.0329), systemic hypertension (risk ratio 1.81, p = 0.0011), diabetes mellitus (risk ratio 2.87, p <0.0001), previous stroke (risk ratio 3.18, p <0.0001), and previous MI (risk ratio 2.15, p <0.0001). In conclusion, statins decrease the incidence of new stroke or MI or death in patients with severe carotid arterial disease who do not undergo revascularization.

Aged↗
PubMed2006

Association of hemoglobin A(1c) level with the severity of coronary artery disease in patients with diabetes mellitus.

Coronary angiography was performed in 152 men and 163 women with diabetes mellitus (mean age 55 +/- 8 years) because of chest pain. The mean hemoglobin A(1c) level was 6.66 +/- 0.58% in 132 patients with 0-vessel coronary artery disease (CAD), 8.00 +/- 0.84% in 40 patients with 1-vessel CAD, 8.83 +/- 1.45% in 76 patients with 2-vessel CAD, and 10.40 +/- 2.28% in 67 patients with 3- or 4-vessel CAD. There was a significant increasing trend of hemoglobin A(1c) levels over the increasing number of vessels with CAD (p <0.0001).

Angina Pectoris↗
PubMed2006

Brief report: physicians and their personal prostate cancer-screening practices with prostate-specific antigen. A national survey.

BACKGROUND: There is inconclusive evidence that prostate cancer screening with prostate-specific antigen (PSA) reduces mortality. Although PSA testing is widespread, it is unknown how many physicians have taken the PSA test themselves. OBJECTIVE: To determine the prevalence of PSA testing among physicians. DESIGN: Cross-sectional survey. SUBJECTS: A nationwide stratified random sample of urologists (response rate 61%, n=247), Internists (response rate 51%, n=273), and family physicians (response rate 64%, n=249) were surveyed by mail in 2000. After excluding female respondents and men who either reported a positive history of prostate cancer or did not respond to that query, there were 146 urologists, 96 Internists, and 118 family physicians. MEASUREMENTS: Whether physicians had undergone prostate cancer screening with PSA. RESULTS: Eighty-seven percent (155/178) of male physicians aged, 50 and older and 21% (31/150) of white male physicians under age 50 reported having had a PSA test. More urologists than nonurologists in both age groups reported having had a screening PSA test. CONCLUSION: Most physicians aged 50 and older report undergoing PSA testing. This may reflect a belief in its efficacy and contribute to its widespread use.

Confidence Intervals↗
PubMed2005

Electrocardiographic abnormalities in patients with right ventricular dilation due to acute pulmonary embolism.

In a study of 190 patients with acute pulmonary embolism, right ventricular dilation was present in 64 (34%), mean age 58 +/- 15 years. The 18 electrocardiographic abnormalities on the 12-lead electrocardiogram had a sensitivity of 8-69%, a specificity of 70-98%, a positive predictive value of 23-69%, a negative predictive value of 64-83%, a likelihood ratio for a positive test of 1.3-4.4, and a likelihood ratio for a negative test of 0.41-1.10 in predicting right ventricular dilation in patients with acute pulmonary embolism.

Acute Disease↗
PubMed2005

Growth hormone treatment enhances nutrition and growth in children with cystic fibrosis receiving enteral nutrition.

OBJECTIVES: Impaired longitudinal growth and poor weight gain are common and important problems in children with cystic fibrosis. This study evaluates the hypothesis that adjunctive growth hormone (GH) therapy augments the growth response to nutritional supplementation. STUDY DESIGN: We recruited 18 prepubertal children who received enteral nutritional supplementation for at least 2 years before enrollment. Nine were randomly assigned to receive no GH for 1 year, followed by 1 year of GH. Nine were randomly assigned to receive 1 year of GH followed by a second year of GH. Measurements included height, weight, pulmonary function, lean tissue mass, bone mineral content, hospitalizations, outpatient antibiotic use, and caloric intake. RESULTS: Growth hormone resulted in significant improvement in height, weight, bone mineral content, lean tissue mass, and number of hospitalizations. Pulmonary function was similar at baseline. Absolute forced vital capacity and forced expiratory volume in 1 minute significantly increased in GH treatment, but there was no significant change in percent predicted pulmonary function. Caloric intake was similar in both groups during both years. CONCLUSIONS: These results suggest that GH is a useful for enhancing growth in children with cystic fibrosis receiving enteral nutritional supplementation.

Blood Glucose↗
PubMed2005

Effect of dropouts on sample size estimates for test on trends across repeated measurements.

Sample size calculation is an important component at the design stage of clinical trials. We investigate the implications of dropouts for the sample size estimates in testing differences in the rates of changes produced by two treatments in a randomized parallel-groups repeated measurement design. Statistical models for calculating sample sizes for repeated measurement designs often fail to take into account the impact of dropouts correctly. In this article, we examine the impact of dropouts on sample size estimate and compare the power with the approach of Jung and Ahn [Jung, S. H., Ahn, C. (2003). Sample size estimation for GEE method for comparing slopes in repeated measurements data. Stat. Med. 22: 1305-1315] with that suggested by Patel and Rowe [Patel, H., Rowe, E. (1999). Sample size for comparing linear growth curves. J. Biopharm. Stat. 9:339-350] through a simulation study.

Clinical Trials as Topic↗
PubMed2005

A retrospective study of growth hormone use in adolescents with cystic fibrosis.

OBJECTIVES: Studies of growth hormone (GH) effectiveness in prepubertal children with cystic fibrosis (CF) have been published previously. We present a retrospective study of GH treatment in adolescents with CF. STUDY DESIGN: We performed a retrospective evaluation of data from 25 pubertal adolescents (ages 13 years 4 months to 16 years 11 months, Tanner stage III or IV). Thirteen (4 F) were followed for 1 year, then received 1 year of treatment with GH (GHTX). We compared the results with a 'control' group of 12 (4 F) whose growth was followed for 1 year (NonTX) but who were not treated with GH at the time of this review. Anthropometric data included: height, weight, lean tissue mass (LTM) and bone mineral content (BMC). Pulmonary function, number of hospitalizations, glycosylated haemoglobin (HbA1c), random blood glucose levels, IGF-I, oestradiol and testosterone levels are also reported. RESULTS: There was no difference between the groups at baseline. After 1 year, GHTX had significantly greater height and weight velocity, height and weight Z-scores, body mass index (BMI), LTM and BMC. Absolute pulmonary function was better and hospitalizations were fewer in the GHTX. No subject developed glucose intolerance or had any other side-effects. CONCLUSION: These results suggest that GH use in pubertal adolescents with CF safely improves height, body weight, bone mineralization and clinical status.

Adolescent↗
PubMed2005

Growth hormone improves bone mineral content in children with cystic fibrosis.

AIM: Osteoporosis and osteopenia have been reported as common complications of cystic fibrosis (CF); however, little is known about accrual of bone mineral in CF. The goal of our study was to measure bone mineral content (BMC) in non-acutely-ill, but poorly growing children with CF, and to determine the relationship between height, lean body mass and BMC. Our second aim was to evaluate the effect of one year of treatment with human recombinant growth hormone (GH) on total body BMC. METHODS: We measured total-body BMC using dual energy X-ray absorptiometry in 32 poorly growing (height < or =10th percentile for age) prepubertal Caucasian children (ages 7 years 6 months-12 years 9 months, 17 M and 15, F) with CF. BMC and lean tissue mass (LTM) were measured at baseline, at 6 months and one year. One half of the children were randomly assigned to receive treatment with GH (GHTX). Results were compared to reference data maintained for healthy children matched for age and ethnicity. Sex steroid and IGF-I levels were also measured. RESULTS: Children with CF exhibited lower total body BMC and LTM than age-, ethnicity- and gender-matched controls. This was still apparent when the data were matched for height and bone age. BMC correlated with height, LTM, and IGF-I levels. Although at baseline the groups were similar, the GHTX group demonstrated significantly greater increase in height, weight, LTM and BMC than the NonTX group. These differences remained despite correction for increase in height CONCLUSION: Our study is the first to evaluate BMC in children with CF and suggests that poor accumulation of bone mineral is a problem. We have further demonstrated that GH treatment improves accumulation of bone mineral.

Absorptiometry, Photon↗
PubMed2004

Elderly nursing home patients with congestive heart failure after myocardial infarction living in new york city have a higher prevalence of mortality in cold weather and warm weather months.

BACKGROUND: Some studies have found an increase in cardiac events in the winter months. Other studies, from cities in the southern half of the United States, have shown an increase in cardiac events during the summer months. METHODS: We investigated in a prospective study of 517 patients, mean age 81 +/- 8 years, with congestive heart failure (CHF) after prior myocardial infarction who died in a nursing home in New York City with 24-hour on-site physician coverage, whether there was a seasonal variation in mortality from CHF. The exact binomial test was used to see if the number of deaths from CHF in the cold weather and warm weather months was significantly different from those in the spring and fall. RESULTS: Of 517 patients who died, 321 deaths (62%) occurred during the months of December, January, February, March, July, and August, and 196 deaths (38%) occurred during the other 6 months (p <.0001). CONCLUSION: The number of deaths in patients with CHF after prior myocardial infarction in cold weather and warm weather months is significantly higher than those in spring and fall months (p <.0001).

Aged↗
PubMed2004

Videocapsule endoscopy versus barium contrast studies for the diagnosis of Crohn's disease recurrence involving the small intestine.

OBJECTIVES: Historically, suspected Crohn's disease (CD) has been evaluated with small bowel follow-through (SBFT) or enteroclysis (equally accurate). This study was undertaken to determine the accuracy of videocapsule endoscopy (VCE) in the diagnosis of CD relative to SBFT and clinical/laboratory indices of CD activity. Previous investigations have used VCE for the diagnosis of suspected CD in patients presenting with a variety of gastrointestinal symptoms. This is the first study to evaluate the occurrence of active disease in patients with known CD. METHODS: Thirty subjects (22 female, 8 male, aged 36.9 +/- 14.2 yr); all with prior CD diagnosis made on the basis of standard criteria (5.5 +/- 6.5 yr prior to study), in whom recurrent CD was suspected based on abdominal pain, diarrhea, anemia, and/or arthralgias. Subjects were studied in a prospective, blinded evaluation of VCE versus SBFT. SBFT was performed first; those with stricture and proximal bowel dilation were excluded from further study. For SBFT, studies were graded as grade 0 (normal), grade 1 (minimal nodularity, ulcerations, normal luminal diameter, < 5 cm involved), grade 2 (more extensive ulcers, minimal luminal narrowing, 5-10 cm involved), or grade 3 (fistula, skip areas, extensive ulceration, >10 cm involved). VCE was performed within 1 wk of SBFT. Serum was obtained for ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein), stool was obtained for alpha-1 antitrypsin, and the Harvey Bradshaw index of CD severity was calculated. VCE (digitalized video) was graded as grade 0 (normal), grade 1 (erythema, isolated villi loss), grade 2 (erosion, no ulcer), or grade 3 (ulcers, spontaneous bleeding, and/or stricture). RESULTS: Twelve patients were excluded for small bowel obstruction. VCE and SBFT scores highly correlated (r = 0.65; p= 0.001). Active CD was visualized in 21 of 30 patients with videocapsule endoscopy and in 20 of 30 patients with SBFT. Complete agreement occurred in 13 of 30 studies; 13 of 17 studies differed by one grade. SBFT found mucosal disease in 20 of 30 patients and VCE found mucosal disease in 21 of 30 patients. VCE found mucosal disease in 6 patients (5 in grade 1, 1 in grade 3) with normal SBFT. SBFT showed CD in 5 patients (all grade 1) with normal VCE. Neither VCE nor SBFT scores correlated with biological or clinical indices. Patient satisfaction was superior for VCE. CONCLUSIONS: VCE and SBFT are complementary for the diagnosis of CD. SBFT may be required to detect strictures as the videocapsule may not pass. However, some strictures may also be missed with SBFT. VCE is less invasive, less time-consuming for the patient than SBFT, and avoids radiation exposure, although reading time is greater for the gastroenterologist than the radiologist. Given that patients with clinically suspected CD recurrence may not have active disease, unnecessary and potentially harmful empiric therapy is not warranted without imaging.

Adult↗
PubMed2004

Do men know that they have had a prostate-specific antigen test? Accuracy of self-reports of testing at 2 sites.

This study determined the accuracy of self-reports of prostate-specific antigen (PSA) testing. Men (N = 402) attending 2 outpatient clinics were asked: "Did you have a PSA test today?" and their medical records were checked. Concordance, sensitivity, and false-negative values were 65%, 67%, and 33%, respectively, at 1 clinic site and 88%, 64%, and 36% at the other. The accuracy of self-reports of PSA testing should be interpreted with caution.

Aged↗
PubMed2003

The variable number of tandem repeat polymorphism of platelet glycoprotein Ibalpha and risk of coronary heart disease.

Glycoprotein (GP) Ib-IX-V complex plays an important role in formation of platelet-fibrin clot at the area of damaged vessel wall. One polymorphism of GP Ibalpha, the main component of GP Ib-IX-V complex, is due to variable numbers of tandem repeats (VNTRs) in the macroglycopeptide region of this molecule. We studied the association between the presence of different VNTR alleles of GP Ibalpha and the frequency of coronary heart disease (CHD) among individuals recruited to a large community-based case-cohort study (Atherosclerosis Risk in Communities [ARIC] study). We found that the distribution of VNTR alleles of GP Ibalpha is different among whites and African Americans. The B allele (with 3 repeats) of GP Ibalpha is relatively more common among African Americans compared with whites. In African Americans, the CC genotype (homozygous with 2 repeats) is associated with a lower risk of CHD events than all other genotypes.

Alleles↗
PubMed2003

Effect of simvastatin versus placebo on treadmill exercise time until the onset of intermittent claudication in older patients with peripheral arterial disease at six months and at one year after treatment.

Simvastatin significantly increased treadmill exercise time until onset of intermittent claudication from baseline by 54 seconds (a 24% increase, p <0.0001) at 6 months after treatment and by 95 seconds (a 42% increase, p <0.0001) at 1 year after treatment. At 6 months and 1 year after treatment with placebo, treadmill exercise time until onset of intermittent claudication was not significantly different from baseline exercise time.

Aged↗
PubMed2003

Sample size estimation for GEE method for comparing slopes in repeated measurements data.

Sample size calculation is an important component at the design stage of clinical trials. Controlled clinical trials often use a repeated measurement design in which individuals are randomly assigned to treatment groups and followed-up for measurements at intervals across a treatment period of fixed duration. In studies with repeated measurements, one of the popular primary interests is the comparison of the rates of change in a response variable between groups. Statistical models for calculating sample sizes for repeated measurement designs often fail to take into account the impact of missing data correctly. In this paper we propose to use the generalized estimating equation (GEE) method in comparing the rates of change in repeated measurements and introduce closed form formulae for sample size and power that can be calculated using a scientific calculator. Since the sample size formula is based on asymptotic theory, we investigate the performance of the estimated sample size in practical settings through simulations.

Data Interpretation, Statistical↗