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Biomedical subjects

C Ahn

Publications and source records attributed to C Ahn.

At least 145 records · Page 8Linked to original sources
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

Idiopathic retroperitoneal fibrosis presented as an abdominal mass and nephrotic syndrome.

We present a 30-year-old male patient who was initially diagnosed as minimal change nephrotic syndrome, 5 years later, the patient developed a localized form of idiopathic retroperitoneal fibrosis (IRF). An elevated ESR and concomitant nephrotic syndrome in the patient suggested the immunologic nature of IRF, IRF has been reported in association with collagen diseases and rarely with proliferative and nonproliferative glomerulopathies. To our knowledge, the association between minimal change lesion (MC) and IRF has not been reported. Furthermore, the fact that IRF presented itself as an abdominal mass and lacked systemic symptoms was also unusual.

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↗
PubMed1997

High-dose infusional doxorubicin and cyclophosphamide: a feasibility study of tandem high-dose chemotherapy cycles without stem cell support.

The purpose of this study was to determine the maximally tolerated dose of doxorubicin administered during two cycles of intensive chemotherapy with cyclophosphamide and doxorubicin without stem cell support in patients with advanced cancer and to assess the cumulative cardiac toxicity of the regimen by noninvasive radionuclide imaging and by pre-and postchemotherapy endomyocardial biopsies. Thirty-eight patients (thirty-six with high risk or metastatic breast cancer) were treated in a dose-escalation trial using a fixed dose of i.v. cyclophosphamide (4.2 g/m2) administered over 2 h on day 5 and escalating doses of doxorubicin (50-175 mg/m2) given as a 96-h continuous i.v. infusion on days 1-4, using Filgrastim (granulocyte colony-stimulating factor) for hematological support beginning on day 6. All patients underwent pretreatment, and 28 patients underwent postchemotherapy endomyocardial biopsies. Twenty-nine of 38 patients received two cycles of treatment (median number of days between cycles, 44; range, 34-62). Twenty-one patients had received doxorubicin previously at cumulative dose levels </=150 mg/m2; all patients had pretreatment endomyocardial biopsy scores less than 1. One patient treated at the highest dose level of doxorubicin (175 mg/m2) developed symptoms of mild congestive heart failure following two cycles of chemotherapy. Pre- and posttreatment radionuclide ejection fractions were 65 and 45%, respectively; this patient had a posttreatment endomyocardial biopsy score of 1 (damage to <5% of myocytes). One additional patient at this dose level had an asymptomatic biopsy score of 1, with a decrease in ejection fraction from 62 to 43%; this recovered to 58% 5 months after completion of chemotherapy. Six additional patients treated at lower dose levels had abnormal posttreatment endomyocardial biopsies without abnormal posttreatment ejection fractions. Nine patients received only one cycle of chemotherapy: five patients due to decreased cardiac ejection fraction following cycle 1 (two of these patients had normal endomyocardial biopsies, and two patients had biopsy scores of 1); one patient secondary to tumor progression following cycle one; one patient due to persistently detectable Clostridium difficile toxin in the stool; one patient refused cycle two; and one patient died following cycle one of complications related to sepsis. A single patient experienced a grand mal seizure associated with orthostatic hypotension, which was considered the dose-limiting toxicity. The median duration (over two cycles) of granulocytopenia (absolute granulocyte count <500/microliter) at the maximally tolerated dose level of 150 mg/m2 was 8.5 days (range, 5-13 days), and the median duration of thrombocytopenia (platelets <20,000/microliter) was 2.5 days (range, 0-9 days). The median duration of hospitalization including chemotherapy administration was 23 days (range, 19-36 days). Other toxicities included stomatitis, fever, diarrhea, and emesis. One patient developed acute leukemia 54 months posttreatment. We conclude that two courses of high-dose cyclophosphamide and doxorubicin using granulocyte colony-stimulating factor are feasible and safe with tolerable myocardial toxicity as evidenced by serial endomyocardial biopsies. The dose-limiting toxicity encountered was a grand mal seizure. The recommended Phase II dose is doxorubicin 150 mg/m2 administered as a 96-h infusion on days 1-4, with cyclophosphamide 4. 2 g/m2 on day 5 and G-CSF 5 microgram/kg/day started on day 6 and administered until the total WBC is above 10,000/microliter for three consecutive days.

Adult↗
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↗
PubMed1996

Risk factors for new atherothrombotic brain infarction in 664 older men and 1,488 older women.

The relation between obesity and new ABI is also unclear. The Framingham Study found that relative weight was not a risk factor for new ABI in older men but was a weak risk factor for new ABI in older women. Barrett-Connor and Khaw found no association between body mass index and new ABI in older men or women. The present study showed that obesity was not a risk factor for new ABI in older men. Obesity was a risk factor for new ABI in older women by univariate analysis but not by multivariate analysis. However, because obesity is associated with other risk factors for ABI and new coronary events, we would try to lower weight in obese older men and women.

Age Factors↗
PubMed1996

Polygenic inheritance of Tourette syndrome, stuttering, attention deficit hyperactivity, conduct, and oppositional defiant disorder: the additive and subtractive effect of the three dopaminergic genes--DRD2, D beta H, and DAT1.

Polymorphisms of three different dopaminergic genes, dopamine D2 receptor (DRD2), dopamine beta-hydroxylase (D beta H), and dopamine transporter (DAT1), were examined in Tourette syndrome (TS) probands, their relatives, and controls. Each gene individually showed a significant correlation with various behavioral variables in these subjects. The additive and substractive effects of the three genes were examined by genotyping all three genes in the same set of subjects. For 9 of 20 TS associated comorbid behaviors there was a significant linear association between the degree of loading for markers of three genes and the mean behavior scores. The behavior variables showing the significant associations were, in order attention deficit hyperactivity disorder (ADHD), stuttering oppositional defiant, tics, conduct, obsessive-compulsive, mania, alcohol abuse and general anxiety-behaviors that constitute the most overt clinical aspects of TS. For 16 of the 20 behavior scores there was a linear progressive decrease in the mean score with progressively lesser loading for the three gene markers. These results suggest that TS, ADHD, stuttering oppositional defiant and conduct disorder, and other behaviors associated with TS, are polygenic, due in part to these three dopaminergic genes, and that the genetics of other polygenic psychiatric disorders may be deciphered using this technique.

Adolescent↗
PubMed1996

Endothelial area as a prognostic indicator for invasive breast carcinoma.

BACKGROUND: Vascular enumeration using antibodies to Factor VIII has been reported to be an independent prognostic indicator of invasive breast carcinoma. METHODS: To eliminate potential subjectivity in distinguishing between individual vessels, especially in areas of tangled capillaries, total endothelial area (EA) was assessed using a Samba 4000 image analyzer. One hundred seventy-eight invasive breast carcinomas (Stage 1 and 2, mean follow-up: 71 months) were immumostained for the presence of CD34, the human hematopoietic progenitor cell antigen also present in endothelium, and EA was quantitated within 5 adjacent 20X fields (0.74 mm2). Additionally, these same vessels were manually counted from the image analyzer. Manual counts were also made from a photomicrograph representative of a single 10X field (1.06 mm2). RESULTS: High grade carcinomas contained greater endothelial area than low grade carcinomas (P = 0.0001). Endothelial area was prognostically significant (P = 0.004) in univariate analysis of disease-free survival (DFS) and overall survival (OS), as were stage of disease, tumor size, and combined histologic grade (P < or = 0.024). Manual vessel counts from the monitor were significant for OS only. Manual vessel counts from photomicrographs showed no statistically significant association with DFS or OS. In multivariate analysis, EA, but not vessel enumeration, remained as an independent predictor for OS (lymph node negative patients only, n = 87) and for DFS (lymph node positive patients only, n = 91). For the entire group of patients (lymph node negative and lymph node positive) independent predictors of DFS and OS were tumor grade and size (P < or = 0.006). CONCLUSIONS: Of the three methods used to evaluate tumor angiogenesis, total endothelial area, as objectively evaluated by image analysis, was the only independent prognostic indicator for OS for patients with lymph node negative invasive breast carcinoma.

Adult↗
PubMed1996

Risk factors for new coronary events in a large cohort of very elderly patients with and without coronary artery disease.

Independent risk factors for new coronary events in older men include age, prior coronary artery disease, cigarette smoking, systemic hypertension, diabetes mellitus, serum total cholesterol, and serum high-density lipoprotein cholesterol (inverse association). Independent risk factors for new coronary events in older women include age, prior coronary artery disease, cigarette smoking, systemic hypertension, diabetes mellitus, serum total cholesterol, serum high-density lipoprotein cholesterol (inverse association), and serum triglycerides (weak association).

Aged↗
PubMed1996

Correlation of paroxysmal supraventricular tachycardia, atrial fibrillation, and sinus rhythm with incidences of new thromboembolic stroke in 1476 old-old patients.

The relationship between supraventricular tachycardia and the incidence of thromboembolic stroke has not been previously reported. We investigated in a prospective study the incidence of new thromboembolic stroke in 1476 patients, mean age 81 years, with atrial fibrillation, paroxysmal supraventricular tachycardia, or sinus rhythm detected by 24-hour ambulatory electrocardiograms. New thromboembolic stroke developed at 31-month follow-up in 87 of 201 patients (43%) with atrial fibrillation, at 43-month follow-up in 84 of 493 patients (17%) with paroxysmal supraventricular tachycardia, and at 45-month follow-up in 143 of 782 patients (18%) with sinus rhythm (p < 0.0001 comparing atrial fibrillation with paroxysmal supraventricular tachycardia or sinus rhythm). Kaplan-Meier survival curves showed a higher significance of thromboembolic stroke in patients with atrial fibrillation, compared to patients with paroxysmal supraventricular tachycardia or sinus rhythm (log-rank: p < 0.0001). Multivariate Cox regression model showed that independent significant predictors of thromboembolic stroke were: a) atrial fibrillation (relative risk = 3.31); b) prior thromboembolic stroke (relative risk = 2.85); c) sex (relative risk for women = 0.75); and d) age (relative risk = 1.02). These data show that atrial fibrillation is an independent predictor of thromboembolic stroke in elderly patients, and that paroxysmal supraventricular tachycardia is not associated with thromboembolic stroke.

Aged↗
PubMed1996

Delayed primary repair of intrathoracic esophageal perforation: is it safe?

The management of intrathoracic esophageal perforation with delayed diagnosis is a subject of controversy. Because of the obvious advantages of primary repair as a simple single-stage operation, this technique was preferentially used to treat 18 of 22 consecutive patients with esophageal perforation. These patients were stratified into three groups according to the time interval between perforation and repair: group A, less than 6 hours, five patients (28%); group B, 6 to 24 hours, six patients (33%); and group C, more than 24 hours, seven patients (39%). Group A patients were older (p < 0.05) and group B had fewer iatrogenic perforations (B, 17%; A, 80%; C, 57%, p < 0.1). Additional tissue was used to buttress the repair site in all three groups (A, 3/5 patients, 60%; B, 4/6 patients, 67%; C, 6/7 patients, 86%; p = not significant). In seven patients (39%), a fundic wrap was used to reinforce the site of primary repair. The outcomes of the three groups were analyzed. Group A had the lowest proportion of postoperative leaks (A, 0/4 patients, 0%; B, 4/6 patients, 67%; C, 5/6 patients, 83%; p < 0.05) and postoperative morbidity (A, 2/5 patients, 40%; B, 6/6 patients, 100%; C, 6/7 patients, 86%; p < 0.1). However the increased incidence of leak and morbidity did not lead to an increase in mortality. One death occurred in each group, with an overall mortality of 17% (A, 1/5 patients, 20%; B, 1/6 patients, 17%; C, 1/7 patients, 14%; p = not significant). We conclude that in the era of advanced intensive care capabilities, primary repair of intrathoracic esophageal perforation can be safely accomplished in most patients regardless of the time interval between perforation and operation. Leakage at the suture site is common unless primary repair is carried out without delay. Postoperative leakage, however, is usually inconsequential and does not necessarily result in an adverse outcome.

Aged↗
PubMed1996

Cost and outcome of osteocutaneous free-tissue transfer versus pedicled soft-tissue reconstruction for composite mandibular defects.

Thirty-nine patients underwent reconstruction of composite mandibular defects following resection for squamous cell carcinoma. Thirty-four underwent immediate reconstruction, while 5 were reconstructed secondarily. Twenty-one received soft-tissue reconstruction only with a pectoralis major myocutaneous flap, 14 underwent osteocutaneous free-tissue transfer, and 4 received a reconstruction plate with free-tissue transfer for soft-tissue coverage. The mandibular defects in the pectoralis major myocutaneous flap group tended to be posterolateral, while free-tissue transfer defects were more severe, usually involving the anterior mandible. Length of surgery and duration of intensive care unit care were significantly longer for free-tissue transfer patients, while flap complications were more common in the pectoralis major myocutaneous flap patients. Facial appearance scores were higher for the free-tissue transfer group by both patient and physician assessment. Social function, speech, and oral function did not differ significantly. Patients reconstructed secondarily with free-tissue transfer reported significant improvement in appearance, oral continence, and social function, with little change in speech intelligibility, deglutition, or diet tolerance. The cost of the main hospitalization was significantly higher in the free-tissue transfer group than in the pectoralis major myocutaneous flap group, although when the costs of subsequent hospitalizations are included, the difference in total cost narrows. Despite more adverse defects, free-tissue transfer provided more predictable aesthetic results and expeditious return to normal social function than did pectoralis major myocutaneous flap reconstruction. The fiscal impact of these complex reconstructions is, however, significant. Cost-containment issues are presented and recommendations are made.

Aged↗
PubMed1996

Prevalence of atrial fibrillation and association of atrial fibrillation with prior and new thromboembolic stroke in older patients.

OBJECTIVE: To correlate atrial fibrillation with the incidence of new thromboembolic (TE) stroke in older patients with and without prior TE stroke. DESIGN: In a prospective study of 2101 older patients, electrocardiograms showed that atrial fibrillation was present in 283 patients (13%). At 42-month mean follow-up, atrial fibrillation was associated with the incidence of new TE stroke in patients with and without prior TE stroke. SETTING: A large long-term health care facility where 2101 older patients were studied. PATIENTS: The 2101 patients included 1451 women and 650 men, mean age 81 +/- 8 years (range 60 to 103). MEASUREMENTS AND MAIN RESULTS: Atrial fibrillation was present in 283 of 2101 patients (13%). The mean age was 84 +/- 7 years in patients with atrial fibrillation and 81 +/- 8 years in patients with sinus rhythm (P = .0001). The prevalence of atrial fibrillation was 5% in patients aged 60 to 70 years, 14% in patients aged 71 to 80 years, 13% in patients aged 81 to 90 years, and 22% in patients aged 91 to 103 years (P < .0001). Mean follow-up was 31 +/- 18 months in patients with atrial fibrillation and 44 +/- 27 months in patients with sinus rhythm (P = .0001). Previous TE stroke occurred in 123 of 283 patients (43%) with atrial fibrillation and in 431 of 1818 patients (24%) with sinus rhythm (P < .0001). New TE stroke occurred in 131 of 283 patients (46%) with atrial fibrillation and in 303 of 1818 patients (17%) with sinus rhythm (P < .0001). The log-rank test showed that patients with atrial fibrillation had a significantly higher probability of developing new TE stroke than those with sinus rhythm (P < .0001). The multivariate Cox regression model showed that independent risk factors for new TE stroke were male sex (relative risk = 1.3), prior TE stroke (relative risk = 3.1), and atrial fibrillation (relative risk = 3.3). CONCLUSIONS: Atrial fibrillation, prior TE stroke, and male sex are independent risk factors for the development of new TE stroke in older patients.

Age Factors↗
PubMed1996

Treatment of germ cell cancer with two cycles of high-dose ifosfamide, carboplatin, and etoposide with autologous stem-cell support.

PURPOSE: To evaluate the activity of two cycles of high-dose ifosfamide, carboplatin, and etoposide (ICE) with autologous hematopoietic progenitor cell support (aHPCS) in patients with poor-prognosis, chemotherapeutically sensitive germ cell cancer. PATIENTS AND METHODS: Twenty patients with germ cell tumor who had persistent disease or relapse from standard-risk or high-risk presentation were entered on this pilot study. The entry criteria included relapsed gonadal and extragonadal germ cell cancer unlikely to be cured by standard salvage therapy but without proven refractoriness to chemotherapy. Treatment consisted of two cycles of ICE chemotherapy with mesna uroprotection and aHPCS. On the first cycle, ifosfamide (IFX), 2 gm/m2; carboplatin, 400 mg/m2; and etoposide, 20 mg/kg, were administered on days -6, -5, and -4. On the second cycle, the doses and schedule of carboplatin and etoposide were identical, and patients with normal renal function received additional IFX, 2 g/m2 on day -3 and 1 g/ m2 on day -2. Mesna, 600 mg/m2 every 6 hours, was given until 24 hours following the final dose of IFX on each cycle, and autologous bone marrow and/or peripheral stem-cells were infused on day 0. RESULTS: All twenty patients are assessable for toxicity and current disease status. Two patients received only one cycle of therapy, one because of the development of active hepatitis C following cycle 1, and one because of renal insufficiency. No patient died as a result of protocol therapy, and no patient developed debilitating peripheral neuropathy, symptomatic hearing loss, or severe renal insufficiency requiring dialysis. The median time to recovery of > or = 500 neutrophils/microL and platelets > or = 50,000/microL was day +11 and day +15, respectively. The median maximum creatinine was 1.6 mg/dL on each treatment cycle, and there was no other significant organ toxicity. With a median follow-up of 45 months, nine patients are alive and disease-free following protocol chemotherapy. One patient with embryonal cancer developed progressive pulmonary metastases 3 months after completing high-dose therapy, underwent complete resection of lung metastases, and remains disease-free at 63+ months. Eight patients are continuously disease free at 23+ to 70+ months after protocol therapy. Eleven patients died of progressive disease between 4 and 23 months following completion of treatment. CONCLUSION: These results compare favorably to other studies in similarly selected patients undergoing salvage therapy with one or two cycles of chemotherapy containing high-dose carboplatin and etoposide with or without cyclophosphamide (CTX) or IFX. The excellent safety and tolerability profile of this regimen and its encouraging activity in poor-prognosis patients make it worthy of further study as part of initial therapy in randomized protocols for high-risk disease and early in the treatment of relapsed germ cell cancer.

Adult↗
PubMed1996

On-call workday cardiovascular response. A study of medical residents.

OBJECTIVE: To compare 24 h blood pressure changes in medical residents when on call with those of a normal workday. DESIGN: Ambulatory blood pressure was recorded in 30 normotensive residents (14 men and 16 women) aged 27+/-2 years, during on-call workdays (24 h in the hospital) and then compared with values obtained during a normal 8 h workday. Ambulatory blood pressure was recorded every 15 min during the day (0700-2200 h) and every 20 min during the night (2200-0700 h). RESULTS: The normal workday 24 h ambulatory mean blood pressure rose from 85.0 mmHg to the on-call mean blood pressure of 88.9 mmHg (P < 0.001). During the daytime, ambulatory systolic and diastolic blood pressures rose by 4.6 mmHg (P < 0.001) and 2.7 mmHg (P < 0.001), respectively. During the night-time period, systolic and diastolic blood pressures rose by 5.4 mmHg (P < 0.01) and 4.6 mmHg (P < 0.01), respectively. The nocturnal systolic and diastolic blood pressure elevation was not related to gender, body mass index, waist: hip ratio, physical exercise or smoking habits. CONCLUSION: The on-call workday causes an elevation in mean 24 h blood pressure and only minimal changes in the 24 h blood pressure pattern.

Journal Article↗