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Biomedical subjects

C Ahn

Publications and source records attributed to C Ahn.

At least 127 records · Page 7Linked to original sources
PubMed1998

Normal left ventricular ejection fraction in older persons with congestive heart failure.

STUDY OBJECTIVES: To investigate in older patients with congestive heart failure (CHF) associated with prior myocardial infarction or hypertension the relationship between normal left ventricular (LV) ejection fraction and age, gender, hypertension, prior myocardial infarction, and atrial fibrillation. DESIGN: A prospective study was performed in 572 older patients (age >60 years) with CHF associated with prior myocardial infarction or hypertension and technically adequate two-dimensional echocardiograms for measuring LV ejection fraction. SETTING: A long-term health-care facility. PATIENTS: One hundred seventy-seven men and 395 women, mean age 82+/-8 years, with CHF associated with prior myocardial infarction or hypertension. MEASUREMENTS AND RESULTS: Normal LV ejection fraction (> or = 50%) occurred in 66 of 177 men (37%) and in 221 of 395 women (56%) (p<0.0001). Multiple logistic regression analysis showed that independent risk factors for normal LV ejection fraction in patients with CHF were no prior myocardial infarction (p=0.0001; odds ratio=3.048), female gender (p=0.0004; odds ratio=1.978), and age (p=0.016; odds ratio=1.029). CONCLUSIONS: Normal LV ejection fraction occurred in 50% of 572 older patients with CHF associated with prior myocardial infarction or hypertension. Independent risk factors for normal LV ejection fraction in patients with CHF were no prior myocardial infarction, female gender, and age.

Aged↗
PubMed1998

Metabolic acidosis and urinary acidification defect during the course of hemorrhagic fever with renal syndrome.

To evaluate urinary acidification defect and its contribution to metabolic acidosis (MA) during hemorrhagic fever with renal syndrome (HFRS), we serially analyzed acid-base balance and urinary acidification indices in 10 HFRS patients. Data of the patients were compared with those of 8 normal volunteers (NC). MA was observed in 6 of 8 patients in the oliguric phase, 5 of 7 in the early diuretic phase, 8 of 10 in the late diuretic phase and 2 of 9 in the convalescent phase. HFRS patients with MA had a higher plasma anion gap in the oliguric and early diuretic phases than NC and a higher plasma Cl/Na ratio in the late diuretic phase than NC. As compared with acid-loaded NC, HFRS patients had a higher urine pH in the oliguric, early diuretic and late diuretic phases, a higher urine anion gap (UAG) in the oliguric and early diuretic phases and a lower urinary NH4+ excretory rate in the oliguric, early diuretic and late diuretic phases. Overt distal acidification defect was observed in 6 of 8 patients in the oliguric phase, 3 of 7 in the early diuretic phase, 5 of 10 in the late diuretic phase and none of 9 in the convalescent phase. None of the convalescent patients had latent acidification defect. In conclusion, urinary acidification defect is marked in the oliguric and diuretic phases of severe HFRS and may play a role in the development of a high anion gap (AG) metabolic acidosis in the earlier phase and hyperchloremic MA in the later phase, but rapidly recovers in the convalescent phase.

Acidosis, Renal Tubular↗
PubMed1998

Autoantibodies to beta2-glycoprotein I in systemic lupus erythematosus and primary antiphospholipid antibody syndrome: clinical correlations in comparison with other antiphospholipid antibody tests.

OBJECTIVE: To examine relationships between anti-beta2-glycoprotein (beta2-GPI) antibodies and other antiphospholipid antibody (aPL) tests (aPL ELISA and the lupus anticoagulant or LAC) and the associations of each of these aPL tests with individual clinical manifestations of the antiphospholipid antibody syndrome (APS). METHODS: IgG and IgM anti-beta2-GPI antibodies were determined by ELISA in 281 patients with SLE, primary APS, or other connective tissue diseases. Frequencies, sensitivities, specificities, and predictive values and correlations of anti-beta2-GPI were compared to the aPL ELISA (IgG and IgM) and LAC for individual (and combined) features of APS. RESULTS: Among 139 patients with positive aPL ELISA and/or LAC tests, 57 (41%) had anti-beta2-GPI antibodies (IgG and/or IgM) compared to 11% of patients with SLE negative for these tests (p = 0.00001). In 130 patients with APS, anti-beta2-GPI occurred in 42% and tended to be more specific but less sensitive than the aPL ELISA or LAC. When all 3 aPL tests were combined, the best sensitivities and negative predictive values were achieved; however, specificity and positive predictive values remained low. Anti-beta2-GPI antibodies occurred more frequently in primary APS (58%) vs secondary antiphospholipid syndromes (33%) (p = 0.008, OR = 2.9). Among 79 patients with SLE negative by both aPL ELISA and LAC, 9 (11 %) were positive for anti-beta2-GPI, 7 of whom had clinical features consistent with APS (representing 5% of all with APS). Stepwise multiple logistic regression analysis revealed beta2-GPI to be most strongly associated with neurological syndromes other than stroke, deep venous thrombosis, and recurrent fetal loss, while LAC was most strongly correlated with stroke and thrombocytopenia. IgM aPL antibodies also were independently associated with neurological syndromes and recurrent fetal loss. CONCLUSION: Testing for beta2-GPI antibodies may be clinically useful in the diagnosis of APS but cannot supplant other aPL ELISA or LAC. Multivariate analyses suggest that anti-beta2-GPI antibodies may play a more central role in certain clinical manifestations of APS than antibodies detected by the aPL ELISA or LAC.

Antibodies, Antiphospholipid↗
PubMed1998

Absence of H(+)-ATPase in the intercalated cells of renal tissues in classic distal renal tubular acidosis.

Proton-secretory defect is thought to be a major pathophysiologic mechanism leading to classic distal renal tubular acidosis (dRTA). However, there have been only two case reports demonstrating the absence of proton pump in renal tissues of the patients with Sjögren's syndrome. This study presents two cases of classic dRTA in which the absence of intact H(+)-ATPase was shown in their renal biopsy tissues by immunohistochemistry using a rabbit polyclonal antibody against the 70 kDa catalytic subunit of H(+)-ATPase from bovine brain clathrin-coated vesicles; one of the cases is diagnosed as subclinical Sjögren's syndrome and the other is idiopathic dRTA. A normal human kidney (NC) and the renal biopsy tissues from a patient with chronic tubulointerstitial nephritus whose proton secretory capacity was intact (DC) were compared as controls. The first patient, a 26-year-old woman, presented with quadriparesis. Her serologic tests revealed positive autoantibodies (ANA, SSA; SSB & RF), and a lower lip biopsy confirmed the diagnosis of Sjögren's syndrome. The second patient, a 43-year-old woman, who initially presented with a pathologic fracture of both femoral necks was referred for an evaluation for hypokalemia by the Department of Orthopedic Surgery. Her renal ultrasonography showed medullary calcification, and no autoantibodies were positive. Serum electrolytes and blood gas analyses of the two patients indicated severe hypokalemia and metabolic acidosis, and proton secretory defects were shown by a failure to lower the urine pH during marked acidemia induced by NH4Cl loading and an abnormally low urine-blood pCO2 difference during bicarbonate administration. While stainings with the anti-H(+)-ATPase antibody in NC and DC were strongly positive in intercalated cells in the connecting tubules and collecting ducts, the tissues from both patients with dRTA were devoid of any anti-H(+)-ATPase staining in the intercalated cells. These results support that the pathophysiologic basis of impaired H+ secretion in idiopathic classic dRTA as well as Sjögren's syndrome is the absence of intact H(+)-ATPase pumps in the intercalated cells.

Acidosis, Renal Tubular↗
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↗