Viral agents associated with acute gastroenteritis in Seoul, Korea.

BACKGROUND: The present study was carried out to describe the epidemiologic characteristics of viral gastroenteritis and determine the phylogenetic composition of norovirus strains detected in hospitalized children with acute gastroenteritis in Seoul, Korea. METHODS AND RESULTS: In total, 10,603 stool samples were collected from 2004 to 2008 and tested by RT-PCR or ELISA. In 4,170 (39.3%) samples at least one viral pathogen was present. Rotavirus (RoV) (1,864, 17.5%) was found to be the causative agent followed by norovirus (NoV) (1,845, 17.4%), human adenovirus (HAdV) (266, 2.5%), human astrovirus (HAstV) (194, 1.8%), and sapovirus (SV) (1, 0.009%). Five GI genotypes (GI-1, GI-3, GI-4, GI-8, and GI-9) and eight GII genotypes (GII-2, GII-3, GII-4, GII-6, GII-7, GII-12, GII-16, and GII-17) of NoV were identified in acute gastroenteritis patients in 2008. CONCLUSIONS: The genetic characteristics of norovirus and the epidemiologic patterns of a viral pathogen from acute gastroenteritis patients may give potentially effective data for epidemiological studies in Seoul, Korea.

Molecular characterization of hepatitis A virus isolated from acute gastroenteritis patients in the Seoul region of Korea.

Hepatitis A virus (HAV) is a major public health problem throughout the world. As a result of declining HAV endemic in Korea, an increasing number of children and adolescents have become susceptible to HAV infection. HAV is related with sanitation conditions of the environment and is transmitted via the fecal-oral route, either through person-to-person contact or by contaminated water and food. The present study has been carried out to determine the phylogenetic analysis and circulating patterns of HAV strains detected from hospitalized patients with acute gastroenteritis (AGE) in the Seoul region of Korea. In total, 2,782 stool specimens from hospitalized patients with AGE collected in October 2006 to September 2007 in Seoul were tested for HAV. A pair comparison of the nucleic acid sequence of a 159-bp base region at the putative VP1/2A junction of 85 Seoul isolates revealed that the most common HAV strain circulating in the region during 2006-2007 was subgenotype IA. HAV phylogenetic studies can provide important information on the genetic characteristics of HAV from AGE patients who may subsequently become the source of infection in Korea.

A prospective analysis of the incidence and risk factors associated with junctional ectopic tachycardia following surgery for congenital heart disease.

This study was designed to evaluate the incidence and risk factors associated with the occurrence of junctional ectopic tachycardia (JET) in patients after congenital heart surgery. We prospectively analyzed cardiac rhythm status in 336 consecutive patients undergoing surgery for congenital heart disease at our institution during a 1-year period. The incidence of JET was 8% (27/336). Repairs with the highest incidence of JET were arterial switch operation (3/13, 23%), atrioventricular (AV) canal repair (4/19, 21%), and Norwood repair (2/10, 20%). Compared to patients with no arrhythmias, patients with JET were more likely to be younger (2.75 +/- 2.44 vs 5.38 +/- 7.25 years, p < 0.01), have had longer cardiopulmonary bypass times (126 +/- 50 vs 85 +/- 73, p < 0.01), and have a higher inotrope score (6.26 +/- 7.55 vs 2.41 +/- 8.11, p < 0.01). By multivariate analysis, ischemic time was the only factor associated with JET [odds ratio, 1.01 (confidence interval, 1.005-1.02); p = 0.0014). The presence of JET did not correlate with electrolyte abnormalities. JET is not necessarily related to surgery near the His bundle or hypomagnesemia. Longer ischemic time is the best predictor of JET. Patients undergoing arterial switch operation, AV canal repair, and Norwood repair are at highest risk of postoperative JET and should be considered for prophylactic therapy.

Distress, jaw habits, and connective tissue laxity as predisposing factors to TMJ sounds in adolescents.

Immediately before a craniomandibular examination and measurement of wrist laxity, 96 adolescents answered a questionnaire about jaw habits, jaw activities, symptoms of stress, facial trauma, and TMJ sounds. The sample was divided into five subgroups on the basis of history and stethoscopically detected TMJ sounds. Some groups with TMJ sounds had significantly more jaw habits, jaw activities, and symptoms of stress than the control group (without history and clinically detected TMJ sounds). No significant differences emerged in angular measurement of wrist laxity between groups with TMJ sounds and the control group. This preliminary study indicates that an adolescent's distress may be associated with TMJ sounds. Further studies on subgroups of adolescents with different TMJ-related symptoms and signs are urged.

Effect of posture, hydralazine, and nifedipine on hemodynamics, ventilation, and gas exchange in patients with chronic obstructive pulmonary disease.

A transient relationship between change in cardiac output (CO) and ventilation and a steady-state relationship between VCO2 and ventilation has been documented. We sought to evaluate the steady-state relationship between CO, and minute ventilation (VE) after positional change and after vasodilator administration in 24 patients with chronic obstructive pulmonary disease (COPD) and mild pulmonary hypertension. Cardiac output was 25% higher (p = 0.003) and VE was 25% lower (p = 0.0001) in the supine position. The change in VE showed a strong correlation with the change in VCO2 (r = 0.693; p = 0.0004), but not with the change in CO. Twelve patients received hydralazine 200 mg orally over 24 h, and 12 patients received nifedipine as a single 10-mg oral dose. Cardiac output increased from 5.05 +/- 1.25 L/min to 6.91 +/- 2.07 L/min (p = 0.008) after hydralazine and increased from 4.34 +/- 1.47 L/min to 5.85 +/- 2.15 L/min (p = 0.001) after nifedipine. Minute ventilation increased from 14.8 +/- 3.0 L/min to 17.3 +/- 4.4 L/min (p = 0.008) after hydralazine, but did not change after nifedipine. The change in VE showed a strong correlation with the change in VCO2 after hydralazine (r = 0.889; p = 0.0004) and after nifedipine (r = 0.756; p = 0.005), but did not correlate with the change in CO. These data demonstrate that the change in VE that accompanies positional change or vasodilator administration in patients with COPD is strongly correlated with the change in VCO2 but not with the change in CO when measured under steady-state conditions.

Pulmonary hypertension in chronic obstructive pulmonary disease. Multivariate analysis.

The severity of pulmonary hypertension was evaluated by right cardiac catheterization in 89 patients with stable chronic obstructive pulmonary disease, both at rest and during maximum treadmill exercise. Thirty-one patients were found to have pulmonary hypertension at rest, defined as a mean pulmonary arterial pressure of 20 mm Hg or more. Although the remaining 58 patients had normal mean pulmonary arterial pressure at rest, three developed pulmonary hypertension during exercise (mean pulmonary arterial pressure greater than or equal to 35 mm Hg). Multiple anthropometric, spirometric, radiographic, and gas-exchange variables were analyzed and correlated with the hemodynamic data to define their value in predicting mean pulmonary arterial pressure. While arterial oxygen pressure (PaO2) at maximum exercise was the variable most highly correlated with resting mean pulmonary arterial pressure (r = -0.67), stepwise multiple linear regression analysis indicated that measurement of the diameter of the right descending pulmonary artery and arterial carbon dioxide tension (PaCO2) also contributed to the prediction of mean pulmonary arterial pressure. Spirometric indices of airflow obstruction, hyperinflation, and the diffusing capacity of the lung for carbon monoxide correlated poorly with the severity of pulmonary hypertension and consequently were not useful predictors of mean pulmonary arterial pressure. The threshold criteria of a PaO2 less than 60 mm Hg or a PaCO2 more than 40 mm Hg were reasonably accurate for a diagnosis of pulmonary hypertension. These arterial blood gas criteria were superior to the spirometric and radiographic variables examined in predicting pulmonary hypertension prior to the development of clinically overt cor pulmonale.

Effects of hydralazine on hemodynamics, ventilation, and gas exchange in patients with chronic obstructive pulmonary disease and pulmonary hypertension.

Reports on hemodynamic effects of hydralazine on pulmonary hypertension (primary or secondary) usually include cases with severe disease or with mixed varieties of pulmonary vascular disease. Serious side effects and death have been reported. Effects of this drug on ventilation and gas exchange are unknown. We investigated the short-term effects of hydralazine treatment on hemodynamics, ventilation, and gas exchange in a relatively homogeneous group of patients with severe chronic obstructive pulmonary disease and moderate exertional pulmonary hypertension (mean pulmonary artery pressure, 43 +/- 3 mmHg). Hydralazine produced significant improvement in cardiac index, total pulmonary resistance, and oxygen transport. We also observed significant improvement in alveolar ventilation (mean PaCO2, decreased from 47 +/- 2 to 40 +/- 3 mmHg at rest and from 51 +/- 3 to 43 +/- 3 mmHg during exercise). The severe exertional hypoxemia of the group (mean PaO2, 48 +/- 2 mmHg) improved significantly (mean PaO2, 57 +/- 3 mmHg). Four of 11 patients showed increased exercise tolerance after hydralazine. This change is probably related to a combined improvement in hemodynamics plus a newly observed improvement in gas exchange and ventilation. Three of 14 patients could not tolerate hydralazine because of marked tachycardia. Serious side effects were not observed in the remaining group.

Myocardial stress. Exercise versus sleep in patients with COPD.

Epidemiologic investigation has revealed that patients with pulmonary disease are at increased risk of dying during the early morning hours. To provide a pathophysiologic explanation for these excessive nocturnal mortality statistics, we tested the hypothesis that episodes of arterial O2 desaturation during sleep can produce as severe a stress on the maintenance of myocardial O2 balance as maximal exercise in patients with chronic obstructive pulmonary disease (COPD). Thirty-one subjects with COPD underwent both overnight sleep and treadmill exercise study to their dyspnea-limited maximum. During both activities, systemic blood pressure was directly recorded and myocardial oxygen consumption (MVO2) estimated from the pulse rate (HR) - systolic blood pressure (SBP) product. Arterial O2 content (CaO2) was calculated from hemoglobin concentration and arterial O2 saturation (SaO2) measured by ear oximetry. Using these data and the Fick principle, myocardial blood flow (MBF) was continuously estimated during both exercise and sleep. During sleep, mean SaO2 was 88 +/- 7 percent while the average of the lowest SaO2 recorded for each subject was 71 +/- 14 percent. Episodes of nocturnal oxyhemoglobin desaturation produced consistent elevations in SBP frequently accompanied by an increase in HR. Because this hemodynamic response resulted in increased MVO2 at precisely the times when arterial O2 contents were low, high demands for MBF were generated. The average of the highest individual values for MBF during sleep was 244 +/- 144 (ml/100 g LV/min). This value was not significantly different from the value of MBF = 281 +/- 91 (ml/100 g LV/min) determined for maximal exercise. This finding suggests that the demand for coronary blood flow during episodes of nocturnal hypoxemia can be transiently as great as during maximal exercise in patients with COPD.