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C Ahn

Publications and source records attributed to C Ahn.

At least 19 recordsLinked to original sources
PubMed1997

Association between plasma homocysteine and coronary artery disease in older persons.

The data demonstrate that high plasma homocysteine levels and low plasma folate and vitamin B12 levels are associated with a higher prevalence of coronary artery disease (CAD) in older men and women. Elevated plasma homocysteine levels were observed in 43% of the older men with CAD versus 18% of the older men without CAD, and in 37% of the older women with CAD versus 12% of the older women without CAD.

Age Factors↗
PubMed1997

Effect of propranolol versus no propranolol on total mortality plus nonfatal myocardial infarction in older patients with prior myocardial infarction, congestive heart failure, and left ventricular ejection fraction > or = 40% treated with diuretics plus angiotensin-converting enzyme inhibitors.

At 32-month follow-up of older patients with prior myocardial infarction, congestive heart failure, and a left ventricular ejection fraction > or = 40% treated with diuretics plus angiotensin-converting enzyme inhibitors, and also with digoxin if atrial fibrillation was present, propranolol caused a 35% significant reduction in total mortality and a 37% significant decrease in total mortality plus nonfatal myocardial infarction compared with no propranolol. At 1-year follow-up, propranolol caused a significantly greater increase in left ventricular ejection fraction (6%) and a significantly greater reduction in left ventricular mass (34 g) than did no propranolol (2% and 20 g, respectively).

Adrenergic beta-Antagonists↗
PubMed1997

Purification, cloning, and functional expression of dihydroneopterin triphosphate 2'-epimerase from Escherichia coli.

Dihydroneopterin triphosphate (H2NTP) 2'-epimerase from Escherichia coli catalyzes the epimerization of H2NTP to dihydromonapterin triphosphate (H2MTP). The enzyme was purified 954-fold to apparent homogeneity by a combination of ammonium sulfate fractionation and column chromatography of Cibacron blue 3GA dye ligand, phenyl-Sepharose CL-4B, methotrexate-agarose, and Superdex 200 HR 10/30 FPLC column. The molecular mass of the epimerase determined on a Superdex column was 82.6 kDa, while the subunit molecular mass determined on SDS-polyacrylamide gel electrophoresis was 13.7 kDa. This implies that the epimerase most probably exists as homohexamer. The 20-amino acid sequence from the N terminus was determined (AQPAAIIRIKNLRLRTFIGI). Based on this sequence, the gene encoding the epimerase was cloned using a simple polymerase chain reaction approach. Translation of the nucleotide sequence of the cloned gene revealed the presence of an open reading frame containing 120 amino acids with a predicted molecular mass of 13,993 Da. The epimerase gene located in a 2.3-kilobase BamHI-EcoRI fragment from Kohara's clone 406 was overexpressed 300-fold, which was confirmed by the prominent increase in the 14-kDa protein band on SDS-polyacrylamide electrophoresis gels. It showed no homology with the sequences of isomerases or other enzymes in GenBank/EMBL data bases.

Amino Acid Sequence↗
PubMed1997

Association of plasma renin activity and echocardiographic left ventricular hypertrophy with frequency of new coronary events and new atherothrombotic brain infarction in older persons with systemic hypertension.

In older hypertensive persons, male gender, prior coronary artery disease, prior atherothrombotic brain infarction (ABI), and echocardiographic left ventricular (LV) hypertrophy are independent risk factors for new coronary events; age, prior ABI, and echocardiographic LV hypertrophy are independent risk factors for new ABI. The data suggest that high plasma renin activity in hypertensive older persons is associated with a high risk of new coronary events and of new ABI through its association with echocardiographic LV hypertrophy.

Aged↗
PubMed1997

Association between plasma homocysteine and extracranial carotid arterial disease in older persons.

The data demonstrate that high plasma homocysteine levels and low plasma folate and vitamin B12 levels are associated with a higher prevalence of 40% to 100% extracranial carotid arterial disease (ECAD) in older men and women. Elevated plasma homocysteine levels were observed in 45% of the older men with 40% to 100% ECAD versus 20% of the older men with 0% to 39% ECAD, and in 40% of the older women with 40% to 100% ECAD versus 18% of the older women with 0% to 39% ECAD.

Aged↗
PubMed1997

Association of extracranial carotid arterial disease, prior atherothrombotic brain infarction, systemic hypertension, and left ventricular hypertrophy with the incidence of new atherothrombotic brain infarction at 45-month follow-up in 1,482 older patients.

Comparison of 239 older patients with 40% to 100% extracranial carotid arterial disease (ECAD) with 1,243 older patients with no significant ECAD showed a higher prevalence of systemic hypertension, left ventricular (LV) hypertrophy, and prior atherothrombotic brain infarction (ABI) and a higher incidence of new ABI in patients with ECAD than in patients without ECAD. A multivariate Cox regression model showed that independent predictors of new ABI were ECAD (risk ratio = 2.5), systemic hypertension (risk ratio = 2.3), prior ABI (risk ratio = 2.3), LV hypertrophy (risk ratio = 2.3), and male sex (risk ratio = 1.3).

Aged↗
PubMed1997

Serum ferritin is not a risk factor for extracranial carotid arterial disease in men and women aged > or = 60 years.

In a prospective study of 236 men and 568 women aged > or = 60 years, 40% to 100% extracranial carotid arterial disease (ECAD) was present in 46 men (19%) and in 83 women (15%) (p = NS). The percentage of patients with increased serum ferritin levels and the mean serum ferritin levels were not significantly different between men with and without 40% to 100% ECAD, or between women with and without 40% to 100% ECAD.

Aged↗
PubMed1997

Prevalence of echocardiographic findings in 554 men and in 1,243 women aged > 60 years in a long-term health care facility.

The prevalence of mitral regurgitation, valvular aortic stenosis, aortic regurgitation, hypertrophic cardiomyopathy, idiopathic dilated cardiomyopathy, and of left ventricular hypertrophy was not significantly different in older men and women. Older women had a significantly higher prevalence of rheumatic mitral stenosis, mitral annular calcium, and left atrial enlargement than older men, and older men had a significantly higher prevalence of abnormal left ventricular ejection fraction than older women.

Aged↗
PubMed1997

Local recurrence in breast cancer: implications for systemic disease.

BACKGROUND: Recurrence in breast carcinoma follows a pattern of growth marked by local, regional, or widespread dissemination. Local recurrence may be the harbinger of systemic disease or failure of local control. Delineation of these processes may have implications in treatment. METHODS: A retrospective review found 1,171 patients with stages I and II breast cancer from 1978 to 1990 treated at the City of Hope Medical Center. RESULTS: Twenty-seven percent (n = 313) of patients developed recurrences. These were classified as local, including chest wall and regional nodes (n = 40), local and distant (n = 63), and distant (n = 210). Mean follow-up was 60 months. Multivariate analysis demonstrates tumor size was not different between the three groups, but the presence of positive lymph nodes was: local = 51%, local and distant = 78%, and distant = 64%. The disease-free interval was longest in the local group (42 months) versus the local and distant group (23 months) and distant group (39 months). Median survival was calculated from the time of recurrence: local = 90 months, local and distant = 26 months, and distant = 16 months. CONCLUSIONS: A group of patients with local recurrence have improved survival and do not develop distant disease. This group may benefit from aggressive surgical treatment to control local disease. These data suggest that a subset of breast tumors can act locally aggressive without metastatic potential.

Breast Neoplasms↗
PubMed1997

A computer program for the analysis of over-dispersed counts and proportions.

Over-dispersed binary and count data occur frequently in many fields of application. Examples include occurrence of cavities in one or more teeth, and development of tumors in one or more animals of a litter. Methods of statistical analyses that ignore correlation between observations underestimate the standard errors. Consequently, coverage proportions of confidence intervals and significance levels of tests are distorted. To implement methods for the analysis of correlated binary or count data requires a level of sophistication for data analysis such that one can specify a model for over-dispersion and the correlation between observations. To analyze the over-dispersed binary or count data, one could postulate a specific statistical model and use maximum likelihood methods for the estimation of parameters. However, it may be preferable to employ an approach that does not rely on modeling because the true model is hard to know with confidence. Rao and Scott (J.N.K. Rao and A.J. Scott, Biometrics 48 (1992) 577-585)y and Scott and Rao (A.J. Scott and J.N.K. Rao, submitted for publication, 1995) proposed simple methods for analyzing correlated binary and count data exhibiting over-dispersion relative to a binomial and homogeneous Poisson model. This paper presents the SAS program to implement their methods to analyze over-dispersed binary and count data. To demonstrate the implementation and the usefulness of their methods, we present an application involving sensitivity of a monoclonal antibody and the number of mammary tumors developing in rats.

Animals↗
PubMed1997

Temporal changes and reversibility of carbamylated hemoglobin in renal failure.

The detection of carbamylated hemoglobin (CarHb) is known to be useful in determination of the chronicity of uremia. However, the time course of the in vivo reaction between isocyanic acid and terminal valine residues of the hemoglobin chain is not clearly defined. To assess the temporal relationship and reversibility of carbamylation, we prospectively measured CarHb as micrograms of valine hydantoin per gram of hemoglobin (microg VH/g Hb) by high-performance liquid chromatography in 37 patients with acute renal failure (ARF), 53 patients with chronic renal failure (CRF), and six patients with successful kidney transplant. Patients with ARF had a lower median CarHb concentration (53.2 microg VH/g Hb; range, 24.6 to 97.1 microg VH/g Hb) than those with CRF (115.0 microg VH/g Hb; range, 34.6 to 286.5 microg VH/g Hb; P < 0.01), but had a higher value (53.2 microg VH/g Hb; range, 24.6 to 97.1 microg VH/g Hb) than 31 normal controls (36.6 microg VH/g Hb; range, 19.9 to 62.9 microg VH/g Hb; P < 0.05). In patients with ARF, the CarHb concentration positively correlated with the number of days of illness (r = 0.74; P < 0.01). The patients with ARF of 10 or more days' duration had a higher CarHb concentration (68.7 microg VH/g Hb; range, 36.0 to 93.9 microg VH/g Hb) than those with a shorter duration of ARF (33.7 microg VH/g Hb; range, 24.6 to 55.8 microg VH/g Hb; P < 0.01) despite similar blood urea nitrogen and serum creatinine values. However, they had a lower concentration of CarHb (68.7 microg VH/g Hb; range, 36.0 to 93.9 microg VH/g Hb) than CRF patients with comparable serum creatinine values (112.5 microg VH/g Hb; range, 34.6 to 286.5 microg VH/g Hb; P < 0.01). In patients with a kidney transplant, CarHb concentration declined by 19.7% (range, 12.3% to 35.6%) within 2 to 3 weeks after receiving the graft, while the level of hemoglobin increased by 25% (range, 4.0% to 46.6%) during the same period. Therefore, the total blood CarHb (CarHb x hemoglobin concentration) was not significantly changed. We concluded that the in vivo reaction of carbamylation of hemoglobin progressed during the period of uremia, and there might exist some irreversible preformed CarHb in advanced stages of CRF.

Acute Kidney Injury↗
PubMed1997

Association of postprandial hypotension with incidence of falls, syncope, coronary events, stroke, and total mortality at 29-month follow-up in 499 older nursing home residents.

OBJECTIVE: To investigate whether a marked decrease in postprandial systolic blood pressure correlates with a higher incidence of falls, syncope, new coronary events, new stroke, and total mortality at long-term follow-up in older nursing home residents. DESIGN: In a prospective study of 499 nursing home residents aged 62 years or older, at 29-month mean follow-up, the maximal reduction in postprandial systolic blood pressure was correlated with the incidence of falls, syncope, new coronary events, new stroke, and total mortality. SETTING: A large long-term health care facility. PATIENTS: The 499 ambulatory or wheelchair-bound residents included 354 women and 145 men, mean age 80 +/- 9 years (range 62-100). MEASUREMENTS AND MAIN RESULTS: The mean follow-up was 29 +/- 10 months (range 1-36). At follow-up, falls had occurred in 199 persons (40%), syncope in 72 persons (14%), new coronary events in 139 persons (28%), new stroke in 61 persons (12%), and total mortality in 199 persons (40%). The mean maximal decrease in postprandial systolic blood pressure was 20 +/- 5 mm Hg for persons with falls and 12 +/- 4 mm Hg in persons without falls (P < 0.001); 23 +/- 5 mm Hg in persons with syncope and 14 +/- 5 mm Hg in persons without syncope (P < 0.001); 18 +/- 6 mm Hg in persons with coronary events and 14 +/- 5 mm Hg in persons without coronary events (P < 0.001); 21 +/- 6 mm Hg in persons with stroke and 15 +/- 5 mm Hg in persons without stroke (P < 0.001); and 17 +/- 6 mm Hg in persons who died and 15 +/- 5 mm Hg in persons who did not die (P < 0.001). Maximal decrease in postprandial systolic blood pressure was an independent risk factor for falls, syncope, new coronary events, new stroke, and total mortality. Age was an independent risk factor for new coronary events and for total mortality. Male sex was an independent risk factor for syncope, new coronary events, stroke, and total mortality. Prior falls was an independent risk factor for new falls. Prior syncope was an independent risk factor for new syncope. Prior stroke was an independent risk factor for new stroke. CONCLUSIONS: A marked reduction in postprandial systolic blood pressure in older nursing home residents was associated at long-term follow-up with a higher incidence of falls, syncope, new coronary events, new stroke, and total mortality.

Accidental Falls↗
PubMed1997

Statistical methods for the estimation of sensitivity and specificity of site-specific diagnostic tests.

The performance of periodontal diagnostic tests is often evaluated by estimating their sensitivity and specificity with respect to a traditionally accepted standard test regarded as a "gold standard" in making the diagnosis. Correlated samples of binary data arise in dental research. The fundamental unit for analysis is occasionally the site rather than the patient in site-specific dental studies. Statistical methods that take into account the within-patient correlation should be employed to estimate the sensitivity and the specificity of diagnostic tests since site-specific results within a patient can be highly correlated. Several statistical methods are introduced for the estimation of the sensitivity and the specificity of site-specific diagnostic tests; these techniques are applied to the data from a study involving an enzymatic diagnostic test to motivate and illustrate the estimation of the sensitivity and the specificity of periodontal diagnostic tests.

Analysis of Variance↗
PubMed1997

Magnetic resonance imaging of the kidney in hemorrhagic fever with renal syndrome: its histopathologic correlation.

We present 2 cases of magnetic resonance imaging in hemorrhagic fever with renal syndrome and their histopathologic findings. The low signal intensities along the renal outer medulla in T2-weighted images are persistent ex vivo as well as in vivo, and these are the radiologic counterpart of medullary congestion and hemorrhage. We will discuss the significance of the imaging in the fields of the medical renal disease such as acute renal failure and review the mechanisms of acute renal failure in hemorrhagic fever with renal syndrome.

Adult↗
PubMed1997

Electrochemical treatment of mouse and rat fibrosarcomas with direct current.

Electrochemical treatment (ECT) of cancer utilizes direct current to produce chemical changes in tumors. ECT has been suggested as an effective alternative local cancer therapy. However, a methodology is not established, and mechanisms are not well studied. In vivo studies were conducted to evaluate the effectiveness of ECT on animal tumor models. Radiation-induced fibrosarcomas were implanted subcutaneously in 157 female C3H/HeJ mice. Larger rat fibrosarcomas were implanted on 34 female Fisher 344 rats. When the spheroidal tumors reached 10 mm in the mice, two to five platinum electrodes were inserted into the tumors at various spacings and orientations. Ten rats in a pilot group were treated when their ellipsoidal tumors were about 25 mm long; electrode insertion was similar to the later part of the mouse study, i.e., two at the base and two at the center. A second group of 24 rats was treated with six or seven electrodes when their tumors were about 20 mm long; all electrodes were inserted at the tumor base. Of the 24 rats, 12 of these were treated once, 10 were treated twice. and 2 were treated thrice. All treated tumors showed necrosis and regression for both mice and rats; however, later tumor recurrence reduced long-term survival. When multiple treatments were implemented, the best 3 month mouse tumor cure rate was 59.3%, and the best 6 month rat tumor cure rate was 75.0%. These preliminary results indicate that ECT is effective on the radiation-induced fibrosarcoma (RIF-1) mouse tumor and rat fibrosarcoma. The effectiveness is dependent on electrode placement and dosage.

Animals↗
PubMed1996

Association of average heart rate on 24-hour ambulatory electrocardiograms with incidence of new coronary events at 48-month follow-up in 1,311 patients (mean age 81 years) with heart disease and sinus rhythm.

A prospective study performed in 1,311 men and women, mean age 81 years, with heart disease and sinus rhythm showed at 48-month follow-up that male sex, increasing age, and average 24-hour heart rate measured from 24-hour ambulatory electrocardiograms were independent risk factors for new coronary events. There was a 1.14 times higher chance of developing new coronary events for an increment of 5 beats/min of heart rate after controlling the confounding effect of other risk factors.

Age Distribution↗
PubMed1996

Three-year follow-up shows no association of serum ferritin levels with incidence of new coronary events in 577 persons aged > or = 62 years.

A prospective study of 171 men and 406 women aged > or = 62 years showed that, at 3-year follow-up, increased serum ferritin levels did not increase the incidence of new coronary events in men or women with or without coronary artery disease. The mean serum ferritin levels were not significantly different in men with or without and in women with or without new coronary events.

Aged↗