Biomedical subjects

C Ahn

Publications and source records attributed to C Ahn.

At least 91 records · Page 5Linked to original sources

PubMed2000

Risk factors for symptomatic peripheral arterial disease in older persons in an academic hospital-based geriatrics practice.

OBJECTIVE: To investigate risk factors for symptomatic peripheral arterial disease (PAD) in older persons. DESIGN: A retrospective analysis of charts from all older persons seen from January 1, 1998, through June 15, 1999, at an academic, hospital-based geriatrics practice. SETTING: An academic, hospital-based geriatrics practice staffed by fellows in a geriatrics training program and full-time faculty geriatricians. PATIENTS: A total of 467 men, mean age 80 +/- 8 years, and 1444 women, mean age 81 +/- 8 years, were included in the study. MEASUREMENTS AND MAIN RESULTS: Symptomatic PAD was present in 93 of 467 men (20%) and in 191 of 1444 women (13%) (P = .001). Significant risk factors for symptomatic PAD by univariate analysis were: age (P = .021 in women); cigarette smoking, hypertension, diabetes mellitus, serum total cholesterol, serum high-density lipoprotein (HDL) cholesterol (inverse association), and serum low-density lipoprotein (LDL) cholesterol (P < .001 in men and women); obesity (P = .013 in men and .002 in women); and serum triglycerides (P = .027 in women). Significant independent risk factors for symptomatic PAD by stepwise logistic regression analysis were: age (odds ratio = 1.052 in men and 1.025 in women); cigarette smoking (odds ratio = 2.552 in men and 4.634 in women); hypertension (odds ratio = 2.196 in men and 2.777 in women); diabetes mellitus (odds ratio = 6.054 in men and 3.594 in women); serum HDL cholesterol (odds ratio = .948 in men and .965 in women); and serum LDL cholesterol (odds ratio = 1.019 in men and women). CONCLUSIONS: Significant independent risk factors for symptomatic PAD in older men and women were age, cigarette smoking, hypertension, diabetes mellitus, serum HDL cholesterol (inverse association), and serum LDL cholesterol.

Academic Medical Centers↗

PubMed2000

Effect of high or low frequency electroacupuncture on the cellular activity of catecholaminergic neurons in the brain stem.

Although the opioid system plays a pivotal role in the analgesic effect of electroacupuncture (EA), it has been suggested that other peptidergic systems also may be involved in the therapeutic effect of EA. Among several peptides for EA-induced analgesia, catecholamine (CA) is associated with the descending pain inhibitory system. We evaluated whether the different frequencies of EA modified the cellular activity of central CA synthesizing neurons using double labeling immunohistochemistry between Fos-like immunoreactive (FLI) neurons and dopamine-beta-hydroxylase (DBH)/tyrosine hydroxylase (TH)-positive neurons. We observed that different frequencies of EA increased the number of FLI neurons in catecholaminergic neurons, such as the dorsal raphe (DR), hypothalamic arcuate nucleus (Arc), locus coeruleus (LC), A5 noradrenaline cells (A5), and A7 noradrenaline cells (A7). In addition, different frequencies of EA significantly increased the ratio of colocalization between FLI neurons and TH positive neurons in DR, LC and Arc. Only low frequency EA increased the neuronal activity in Arc. The ratio of double labeling between FLI and DBH positive neurons was also elevated at both LC and A5. These data demonstrate that different frequencies of EA increase the cellular activity of central CA synthesizing neurons, suggesting that the CA system plays an important role in EA-induced analgesia.

Animals↗

PubMed2000

Urinary mercury levels in patients with autoantibodies to U3-RNP (fibrillarin).

OBJECTIVE: Autoantibodies to the U3 nucleolar ribonucleoprotein (RNP) fibrillarin occur in some patients with systemic sclerosis (SSc) or other connective tissue diseases and can be induced in certain mouse strains by injections of mercuric chloride, perhaps due to antigenic alteration of fibrillarin by mercury (Hg). Thus, potential occult exposure to Hg was explored in patients with SSc. METHODS: Urinary Hg levels were measured by cold vapor atomic absorption in 13 patients with antifibrillarin antibodies (11 with SSc), 39 SSc patients without antifibrillarin antibodies, and 32 healthy controls. RESULTS: Mean urinary Hg levels were significantly elevated in the antifibrillarin antibody positive patients compared to those in other patients with SSc and controls. After correction for urinary creatinine levels, mean urinary Hg levels remained significantly different than in the other 2 groups, although Hg levels in all were still within the normal or "unexposed" range. When patients and controls with low urinary creatinine levels were excluded from analysis, there were no significant differences in mean urinary Hg levels among the 3 groups. CONCLUSION: These findings suggest that further epidemiological and basic research studies of mercury are warranted in patients with SSc, especially those expressing antifibrillarin antibodies.

Animals↗

PubMed2000

Fewer women than men have positive SPECT and PET cardiac findings among patients with no history of heart disease.

UNLABELLED: A lower detection rate of coronary artery disease (CAD) has been reported for SPECT imaging in women, despite the fact that similar numbers of women and men die each year of heart disease. Ruling out instrumentation as a possible source of this low detection rate for CAD in women could be important in determining the root cause of this difference. METHODS: Patients were referred by cardiologists and randomized to PET or SPECT by the imaging center. A total of 210 patients (106 women, 104 men) were enrolled in this study, with 105 imaged by dual-isotope SPECT and 105 imaged by 82Rb PET. Rest/stress scanning was performed using dipyridamole. The effects of sex, prior history of CAD, and instrumentation on the detection of positive scans were determined using multiple logistic regression analysis with positive scans as the endpoint. RESULTS: For the total study population, sex and prior history of CAD are significantly associated with positive scans, whereas imaging modality and age are not. There was no significant interaction between sex and prior history of CAD. Men have 4.1-fold greater odds of having a positive nuclear scan than women, and patients with prior history of CAD have 5.2-fold greater odds of a positive scan after controlling for the confounding effects of age and imaging modality. In the subgroup of patients with no prior history of heart disease, men have 3.9-fold greater odds of a positive scan than women, and the odds ratio of a positive scan is 2.5-fold greater for PET than for SPECT. There was no statistical difference in the number of positive scans by SPECT or PET, or positive scans by sex in patients with documented history of CAD. CONCLUSION: Fewer women than men have positive nuclear cardiology scans by both PET and SPECT, despite similar symptoms. Instrumentation characteristics alone do not account for this sex-based difference and suggest the possibility that early CAD may present differently in women than in men.

Aged↗

PubMed2000

Detection of Hantaan and Seoul viruses by reverse transcriptase-polymerase chain reaction (RT-PCR) and restriction fragment length polymorphism (RFLP) in renal syndrome patients with hemorrhagic fever.

BACKGROUND: Hemorrhagic fever with renal syndrome (HFRS), also called Korean hemorrhagic fever (KHF), is the most common cause of acute renal failure in the Far East. Two serotypes of hantavirus, Hantaan and Seoul viruses are known pathogens for HFRS in Korea. PURPOSE: To elucidate the diagnostic applicability for the serotype diagnosis in HFRS patients, we used nested reverse transcriptase-PCR and restriction fragment length polymorphism (nRT-PCR/RFLP) to screen 2 prototype viruses, 11 virus isolates from HFRS patients, and 69 specimens obtained from 31 HFRS patients. METHODS: The nRT-PCR was performed using primers specific for the G1 segments of the Hantaan (HF3 1140-1163, HB14 1363-1342) and Seoul (SF2 809-832, SB3 1200-1177) viruses. The initial PCR products were then further amplified using nested primers for the Hantaan (HF4 1141-1164, HB13 1360-1339) and Seoul (SF7 863-884, SB1 1165-1142 ) viruses. Amplified segments were then digested with restriction enzymes specific for either Hantaan (C1a I) or Seoul (Sac I) virus sequences. RESULTS: In all cultured viruses, the serotypes identified by nRT-PCR/RFLP were consistent with those of PRNT. nRT-PCR/RFLP results indicated the presence of Hantaan virus in 10 patients and of Seoul virus in 15 patients. In 3 patients, both Hantaan- and Seoul-specific amplified bands were visualized in serially collected samples, and in 4 patients no amplicon was detected. Among 69 specimens, 55 were positive; these positive specimens were obtained between days 3 and days 33 of illness. The positive rate was not affected by the clinical phase, day of illness, or severity of HFRS. CONCLUSIONS: nRT-PCR/RFLP is a rapid and convenient method for serotype diagnosis in most HFRS patients. It could also allow detection of genetic variation of hantavirus within the same serotype.

Adult↗

PubMed1999

Association of mitral annular calcium and of aortic cuspal calcium with coronary artery disease in older patients.

In a prospective study, mitral annular calcium (MAC) was present in 274 of 752 men (36%), mean age 80 years, and in 869 of 1,663 women (52%), mean age 82 years (p <0.0001); aortic cuspal calcium was present in 295 of 752 men (39%) and in 672 of 1,663 women (40%) without aortic cuspal calcium (p = NS). Coronary artery disease was present in 150 of 274 men (55%) with versus 192 of 478 men (40%) without MAC (p = 0.0001) and in 446 of 869 women (51%) with versus 276 of 794 women (35%) without MAC (p <0.0001); coronary artery disease was present in 167 of 295 men (57%) with versus 175 of 457 men (38%) without aortic cuspal calcium (p <0.0001), and in 360 of 672 women (54%) with versus 362 of 991 women (37%) without aortic cuspal calcium (p <0.0001).

Aged↗

PubMed1999

Comparison of incidences of congestive heart failure in older African-Americans, Hispanics, and whites.

In a prospective study of 2,893 African-Americans, Hispanics, and whites, mean age 81 years, at 43-month follow-up, congestive heart failure (CHF) developed in 194 of 686 African-Americans (28%), in 67 of 257 Hispanics (26%), and in 533 of 1,950 whites (27%) (p = NS). The Cox regression model showed that significant independent risk factors for CHF were male gender (risk ratio = 1.4, p = 0.0001); hypertension (risk ratio = 2.5, p = 0.0001); coronary artery disease (risk ratio = 4.0, p = 0.0001); diabetes mellitus (risk ratio = 1.6, p = 0.0001); and age (risk ratio = 1.05, p = 0.0001).

Aged↗

PubMed1999

Association of left ventricular hypertrophy and chronic atrial fibrillation with the incidence of new thromboembolic stroke in 2,384 older persons.

In a prospective study of 2,384 persons, mean age 81 years, at 44-month follow-up, new thromboembolic stroke developed in 510 of 2,384 persons (21%). The Cox regression model showed that significant independent risk factors for new thromboembolic stroke were atrial fibrillation (risk ratio 3.2), left ventricular hypertrophy (risk ratio 2.8), prior stroke (risk ratio 2.2), and male gender (risk ratio 1.2).

Aged↗

PubMed1999

Association of extracranial carotid arterial disease and chronic atrial fibrillation with the incidence of new thromboembolic stroke in 1,846 older persons.

In a prospective study of 1,846 persons, mean age 81 +/- 8 years, 281 persons (15%) had 40% to 100% extracranial carotid arterial disease and 253 persons (14%) had chronic atrial fibrillation. The Cox regression model showed that significant independent risk factors for new thromboembolic stroke were atrial fibrillation (p = 0.0001, risk ratio 3.3), 40% to 100% extracranial carotid arterial disease (p = 0.0001, risk ratio 2.5), prior stroke (p = 0.0001, risk ratio 2.1), and male gender (p = 0.045, risk ratio 1.2).

Aged↗

PubMed1999

Risk factors for new atherothrombotic brain infarction in older African-American men and women.

Independent risk factors for new atherothrombotic brain infarction (ABI) in older African-American men were hypertension (risk ratio 4.381), diabetes mellitus (risk ratio 2.872), and previous ABI (risk ratio 1.904). Independent risk factors for new coronary events in older African-American women were cigarette smoking (risk ratio 2.754), hypertension (risk ratio 5.914), diabetes mellitus (risk ratio 3.464), serum total cholesterol (risk ratio 1.008), serum high-density lipoprotein cholesterol (inverse association) (risk ratio 0.958), age (risk ratio 1.026), and previous ABI (risk ratio 2.601).

Black or African American↗

PubMed1999

Comparison of frequency of new coronary events in older subjects with and without valvular aortic sclerosis.

In a prospective study of 1,980 subjects (mean age 81 +/- 8 years) without valvular aortic stenosis, 981 (50%) had valvular aortic sclerosis diagnosed by 2-dimensional and continuous-wave Doppler echocardiography. Independent risk factors for new coronary events were prior coronary artery disease (p = 0.0001, risk ratio 2.8), male gender (p = 0.002, risk ratio 1.3), and valvular aortic sclerosis (p = 0.0001, risk ratio 1.8).

Aged↗

PubMed1999

Associations of anti-beta2-glycoprotein I autoantibodies with HLA class II alleles in three ethnic groups.

OBJECTIVE: To determine any HLA associations with anti-beta2-glycoprotein I (anti-beta2GPI) antibodies in a large, retrospectively studied, multiethnic group of 262 patients with primary antiphospholipid antibody syndrome (APS), systemic lupus erythematosus (SLE), or another connective tissue disease. METHODS: Anti-beta2GPI antibodies were detected in sera using an enzyme-linked immunosorbent assay. HLA class II alleles (DRB1, DQA1, and DQB1) were determined by DNA oligotyping. RESULTS: The HLA-DQB1*0302 (DQ8) allele, typically carried on HLA-DR4 haplotypes, was associated with anti-beta2GPI when compared with both anti-beta2GPI-negative SLE patients and ethnically matched normal controls, especially in Mexican Americans and, to a lesser extent, in whites. Similarly, when ethnic groups were combined, HLA-DQB1*0302, as well as HLA-DQB1*03 alleles overall (DQB1*0301, *0302, and *0303), were strongly correlated with anti-beta2GPI antibodies. The HLA-DR6 (DR13) haplotype DRB1*1302; DQB1*0604/5 was also significantly increased, primarily in blacks. HLA-DR7 was not significantly increased in any of these 3 ethnic groups, and HLA-DR53 (DRB4*0101) was increased in Mexican Americans only. CONCLUSION: Certain HLA class II haplotypes genetically influence the expression of antibodies to beta2GPI, an important autoimmune response in the APS, but there are variations in HLA associations among different ethnic groups.

Alleles↗

PubMed1999

Polymorphism of beta2-glycoprotein I at codons 306 and 316 in patients with systemic lupus erythematosus and antiphospholipid syndrome.

OBJECTIVE: To determine the frequency of mutations in the phospholipid binding domain of beta2-glycoprotein I (beta2GPI) in patients with systemic lupus erythematosus (SLE) and/or antiphospholipid syndrome (APS), and to analyze the clinical correlations of such mutations with thromboembolic complications. METHODS: Exons 7 and 8 of beta2GPI, which encode for its fifth domain, were amplified by polymerase chain reaction, and the presence of mutations was determined by restriction digestion and single-strand conformation polymorphism analysis. A clinical correlation with these mutations and the presence of antiphospholipid antibodies (aPL), lupus anticoagulant (LAC), anti-beta2GPI antibody, and the development of thromboembolic complications was performed using chi-square and Fisher's exact tests. RESULTS: From a total of 143 patients studied, we found that 5.6% were heterozygous for the mutation at exon 7 (codon 306), and 7.7% were heterozygous for the mutation at exon 8 (codon 316). No homozygous subjects were found for either mutation. No significant correlation between these mutations and the presence of aPL, LAC, or anti-beta2GPI antibodies was found. In patients with SLE (n = 95), 4 of 6 patients with exon 8 mutation had thrombosis, compared with 22 of 82 patients without the mutation (P = 0.043). CONCLUSION: The prevalence of mutations in the fifth domain of beta2GPI in these patients with SLE and/or APS were similar to those previously reported for the general population. Heterozygosity for either mutation does not influence the incidence of aPL, but in patients with SLE, the mutation at exon 8 may predispose to thrombosis as an independent factor.

Adult↗

PubMed1999

Thymic selection by a single MHC/peptide ligand: autoreactive T cells are low-affinity cells.

In H2-M- mice, the presence of a single peptide, CLIP, bound to MHC class II molecules generates a diverse repertoire of CD4+ cells. In these mice, typical self-peptides are not bound to class II molecules, with the result that a very high proportion of H2-M- CD4+ cells are responsive to the various peptides displayed on normal MHC-compatible APC. We show here, however, that such "self" reactivity is controlled by low-affinity CD4+ cells. These cells give spectacularly high proliferative responses but are virtually unreactive in certain other assays, e.g., skin graft rejection; responses to MHC alloantigens, by contrast, are intense in all assays. Possible explanations for why thymic selection directed to a single peptide curtails self specificity without affecting alloreactivity are discussed.

Adoptive Transfer↗

PubMed1999

Rapidly developing T-cell posttransplantation lymphoproliferative disorder.

Posttransplantation lymphoproliferative disorder (PTLD) of T-cell origin has been rarely described in chronically immunosuppressed allograft recipients. We report a case of renal PTLD of a T lineage that occurred shortly after transplantation under a triple-immunosuppressive regimen. Renal graft biopsy performed 58 days posttransplantation showed extensive interstitial infiltrates of polymorphic lymphoid cells, which expressed the UCHL-1 and CD3 markers for T-cell lineage. The clonal nature of the T cells in renal tissue was identified by showing rearrangement of the T-cell receptor gamma chain genes using a polymerase chain reaction (PCR). DNA extracted from the graft biopsy specimen did not show the sequences of human T-cell leukemia virus type 1 (HTLV-1) by PCR. Signals for Epstein-Barr virus (EBV) infection in renal tissue were not shown by in situ hybridization. After the reduction of immunosuppressive therapy, regression of PTLD lesion and development of rejection were shown in the second graft biopsy and graftectomy specimen. The extreme rarity of rapidly developing T-cell PTLD in a renal allograft prompted us to write this report.

Adult↗

PubMed1999

The effect of arginine or glycine supplementation on gastrointestinal function, muscle injury, serum amino acid concentrations and performance during a marathon run.

Gastrointestinal bleeding and increased intestinal permeability have been observed in marathon runners. We sought to determine if L-arginine would be useful for prevention of these complications. Twenty-three runners were randomized to receive L-arginine (A) or glycine (placebo) (G), 10 grams 3 times daily for 14 days prior to the 1997 Houston-Methodist Marathon. Serum, stool hemoccults and lactulose:mannitol permeabilities were obtained at baseline, immediately after completion of the marathon and approximately 48 hours later. Runners rated their symptoms of nausea and vomiting, belching and indigestion, abdominal pain and bloating, diarrhea, and extremity pain on a 1-5 scale of increasing severity. The L:M was unchanged in either group during the three collections. Occult bleeding occurred in 8%/20% in A and G groups, respectively, p = NS) immediately post-marathon. No runners had occult bleeding 48 hours post-race. Gastrointestinal symptom scores were minimal to nonexistent. Extremity pain scores were similar for groups A and G (2.1+/-1.4 and 2.8+/-1.6, respectively, (p = NS). Fluid intake was similar between both groups (1875+/-1547 vs. 1506+/-970 ml, p = NS). Serum amylase was normal at baseline and remained virtually unchanged. Serum lipase was normal at baseline and immediately post-race in both groups, but increased at 48 hours post-race (82.2+/-34.3 to 121.5+/-53.3 mg/dl [A], p = 0.02 and 114.3+/-55.7 to 181.9+/-162.2 mg/dl [G], p = 0.09). CPK increased significantly and similarly in both groups immediately post-race, and even more dramatically 48 hours post-race (130.3+/-130.8 to 738.8+/-902.9, p = 0.007 to 1966.5+/-3.166.0 mg/dl [A] and 140.9+/-77.9 to 863.0+/-772.3, p = 0.003 to 5619+/-10636.8mg/dl [G]). Modest post-race decreases were seen in most serum amino acids in both groups. Finish times were longer than predicted (23+/-21 and 9+/-7 min for A and G groups, respectively, p = 0.049). Our study failed to show a clear benefit of arginine supplementation for the prevention of intestinal ischemia/reperfusion injury associated with endurance running, but either a detrimental affect on performance with arginine, or enhanced performance with glycine. Skeletal muscle injury was unaffected by arginine or glycine supplementation. The delayed increase in serum lipase suggests mild pancreatic injury, affected by either arginine or glycine supplementation.

Adult↗

PubMed1999

Problematic formulations of SAS PROC.MIXED models for repeated measurements.

The work reported in this article was undertaken to evaluate the utility of SAS PROC.MIXED for testing hypotheses concerning GROUP and TIME x GROUP effects in repeated measurements designs with drop-outs. If dropouts are not completely at random, covariate control over informative individual differences on which dropout data patterns depend is widely recognized to be important. However, the inclusion of baseline scores and time-in-study as between-subject covariates in an otherwise well formulated SAS PROC.MIXED model resulted in inadequate control over type I error in simulated data with or without drop-outs present. The inadequate model formulations and resulting deviant test sizes are presented here as a warning for others who might be guided by the same information sources to employ similar model specifications when analyzing data from actual clinical trials. It is important that the complete model specification be provided in detail when reporting applications of the general linear mixed-model procedure. A single random-coefficients model produced appropriate test sizes, but it provided inferior power when informative covariates were added in the attempt to adjust for dropouts. As an alternative, the incorporation of covariate controls in simpler two-stage endpoint or random regression analyses is documented to be effective in dealing with dropouts under specifiable conditions.

Biopharmaceutics↗

PubMed1999

Unilateral renal cystic disease in adults.

Unilateral renal cystic disease (URCD) is morphologically indistinguishable from autosomal dominant polycystic kidney disease (ADPKD) except for its unilaterality. Unlike ADPKD, URCD patients show neither a genetic background nor progressive deterioration in renal function; thus, the differential diagnosis of URCD from ADPKD is important. Only a few cases of URCD have been reported. This study reports two cases of URCD in adults together with a literature review. We identified these two cases using abdominal computerized tomography and family screening with renal ultrasonography.

Adult↗