Stem cell factor-induced leukotriene B4 production cooperates with eotaxin to mediate the recruitment of eosinophils during allergic pleurisy in mice.

The understanding of the mechanisms underlying eosinophil recruitment in vivo may aid in the development of novel strategies for the treatment of allergic disorders. In this study, we investigated the role of chemokines in the cascade of events leading to eosinophil recruitment in a stem cell factor (SCF)- and leukotriene B(4) (LTB(4))-dependent allergic pleurisy model in mice. The intrapleural administration of the eosinophil-active chemokines eotaxin, RANTES, and macrophage-inflammatory protein 1alpha (MIP-1alpha) induced a time- and dose-dependent eosinophil recruitment. Pretreatment with anti-eotaxin, but not anti-RANTES or anti-MIP-1alpha, blocked the recruitment of eosinophils following Ag challenge of sensitized animals, and significant eotaxin immunoreactivity was detected in the pleural cavity of these animals. Similarly, only the anti-eotaxin inhibited the eosinophil recruitment induced by injection of SCF in naive animals. However, blockade of SCF did not inhibit the release of eotaxin after Ag challenge of sensitized mice. Akin to its effects on SCF and in the allergic reaction, eotaxin-induced eosinophil recruitment was blocked by the LTB(4) receptor antagonist CP105696. Nevertheless, SCF, but not eotaxin, appeared to regulate the endogenous release of LTB(4) after Ag challenge. Finally, we show that low doses of eotaxin synergized with LTB(4) to induce eosinophil recruitment in the pleural cavity. Overall, the present results show that eotaxin and SCF-induced LTB(4) cooperate to induce eosinophil recruitment into sites of allergic inflammation. Cooperation between inflammatory mediators must be an important phenomenon in vivo, explaining both the ability of lower concentrations of mediators to induce a full-blown functional response and the effectiveness of different strategies at inhibiting these responses.

Frequency of HLA-DQB*06 in Caucasian,African American, and Mexican American patients with a positive direct antiglobulin test.

A reduced frequency of HLA-DQ6 in patients with a positive direct antiglobulin test (DAT) was previously reported but race was undisclosed. Therefore, we investigated a total of 275 patients (80 Caucasian, 113 African American, and 82 Mexican American) and 518 normal controls (205 Caucasian, 208 African American, and 105 Mexican American). These were typed for class II HLA antigens using molecular techniques. A DAT was performed on each patient's red cells drawn into EDTA using both mouse and rabbit polyspecific reagents. Of 275 patients tested, 73 (27%) had a positive DAT (12 Caucasians, 35 African Americans, and 26 Mexican Americans). We found that 5 (42%) Caucasian patients and 103 (50%) Caucasian controls possessed the DQB*06 allele (p =.56). In the African American group, 15 (43%) patients and 91 controls (44%) were DQB*06 positive (p =.92). Six Mexican American patients (23%) and 21 controls (20%) had the DQB*06 allele (p =.72). This article underscores the need to use race-matched controls when genetic disease associations are sought.

Comparative characterization of antigenic epitopes in the immunodominant region of the protein encoded by open reading frame 3 in Burmese and Mexican strains of hepatitis E virus.

To analyse the effect of strain-specific sequence variation on the antigenic properties of the protein encoded by the open reading frame 3 (ORF 3) of hepatitis E virus (HEV), two sets of short overlapping peptides spanning amino acids 91 to 123 of this protein from Burmese and Mexican strains were synthesized and tested with sera obtained from outbreaks of enterically transmitted non-A, non-B hepatitis in three different regions of the world (Mexico, Turkmenistan and Kenya). The data suggest strain-specific variation in the antigenic reactivity of the ORF 3 protein. The C-terminal region of this protein contains several antigenic epitopes located in the most variable positions. Individual sera were found to interact with different groups of epitopes from each set of peptides. The antigenic epitopes of the Mexican strain appear to be less conformation-dependent than those of the Burmese strain. The most immunoreactive epitope of the ORF 3 protein from the Mexican strain was localized at amino acid positions 95 to 101. The ORF 3 protein of the Burmese strain contains an immunodominant epitope at amino acid positions 112 to 117. Some of these short peptides may be useful for the development of a diagnostic assay to discriminate between the Burmese and Mexican strains.

Pharmacokinetics and pharmacodynamics of bumetanide in neonates treated with extracorporeal membrane oxygenation.

Eleven term neonates treated with extracorporeal membrane oxygenation received bumetanide to treat volume overload. All patients had stable renal function, no history of prior diuretic therapy, and no overt evidence of hepatobiliary disease or hypoalbuminemia. Pretreatment creatinine clearance was 35.2 +/- 4.5 ml/min per 1.73 m2 (range, 20.3 to 57.5). Bumetanide, 0.095 +/- 0.003 mg/kg, was administered for 2 minutes into the postmembrane side of the extracorporeal membrane oxygenation circuit. Serial plasma and urine samples were collected for measurement of bumetanide and electrolyte concentrations. Total plasma and renal clearances for bumetanide were 0.63 +/- 0.11 and 0.16 +/- 0.04 ml/min per kilogram, respectively. The steady-state volume of distribution (0.44 +/- 0.03 L/kg) and the elimination half-life (13.2 +/- 3.8 hours) were greater than similar values reported in previous studies of bumetanide disposition in premature and term neonates who were not treated with extracorporeal membrane oxygenation. At observed rates of bumetanide excretion, the diuretic, natriuretic, and kaliuretic responses were linear. Significant diuresis, natriuresis, and kaliuresis were observed, although the duration of these effects was less than expected given the prolonged renal elimination of bumetanide. Nonrenal elimination of bumetanide was variable (47.2% to 96.9%) but higher than expected; this may explain the relatively brief diuretic and kaliuretic response.

Antihypertensive effect and pharmacokinetics of nitrendipine in children.

Nitrendipine, a new calcium-channel antagonist, was used to treat 25 children (aged 6 months to 17 years) with severe hypertension. Systolic and diastolic blood pressures (mean +/- SEM) fell from 148 +/- 2/99 +/- 2 mm Hg to 128 +/- 4/77 +/- 3 mm Hg after 24 hours and to 121 +/- 2/75 +/- 2 mm Hg after 2 weeks. No further reductions in systolic or diastolic blood pressure were observed after continued therapy. Transient reflex tachycardia occurred during the first week of therapy. Other adverse effects were uncommon and included headaches, flushing, palpitations, and edema. Pharmacokinetic parameters were estimated at steady state after an oral dose of 0.56 +/- 0.04 mg/kg in 13 children. Although absolute oral bioavailability could not be determined, estimates of the area under the plasma concentration versus time curve, the apparent peak serum concentration, and the apparent time at which the peak serum concentration occurred indicated that both the rate of absorption and oral bioavailability are variable. Coadministration of nitrendipine with food decreased the rate of absorption and may have reduced oral bioavailability. A relationship between age and the apparent plasma elimination half-life of nitrendipine was not observed. Nitrendipine, 0.25 to 0.5 mg/kg per dose administered orally every 6 to 12 hours, appeared to be an effective and safe treatment for resistant hypertension in infants and children.

Hypoglycemia in pediatric renal allograft recipients.

Symptomatic hypoglycemia developed 5 to 45 months after transplantation in nine children who had renal transplants before 6 years of age. During hypoglycemia, serum glucose levels ranged from 14 to 39 mg/dl (0.8 to 2.1 mmol/L). Hypoglycemic episodes occurred between 1.7 and 7.5 years of age. Six patients had generalized seizures; the remaining three had diaphoresis with stupor or lethargy. None of the children had serious infections, diabetes, congenital defects of glucose metabolism, or a history of treatment with insulin or oral hypoglycemic agents. Six patients had hypoglycemic symptoms after a prolonged fast, and at least four had ketosis. Eight of the nine patients were receiving propranolol when hypoglycemia occurred. No differences in the daily prednisone dose, the number of transplant rejection episodes, or the frequency of treatment with medications other than propranolol were noted between hypoglycemic patients and 56 normoglycemic age-matched renal transplant recipients. All hypoglycemic patients were subsequently treated with frequent feedings and discontinuation of propranolol. No further hypoglycemic episodes have occurred in eight of nine patients. Symptomatic hypoglycemia should be recognized as a potentially devastating complication of pediatric renal transplantation.

A prospective randomized comparison of cefotaxime vs ampicillin and chloramphenicol for bacterial meningitis in children.

Fifty children with bacterial meningitis were prospectively randomized to receive cefotaxime (50 mg/kg/dose every 6 hours) or ampicillin and chloramphenicol in standard doses. Twenty-three patients received cefotaxime and 27 received standard therapy. Bacterial isolates included: Haemophilus influenzae (29), Streptococcus pneumoniae (eight), Neisseria meningitidis (eight), group B streptococci (three), and Salmonella enteritidis (two). Ten (34%) of the H. influenzae isolates were resistant to ampicillin, nine on the basis of beta-lactamase production. All strains were susceptible to cefotaxime. Clinical cure rates for the cefotaxime (100%) and standard therapy (96%) groups were similar; survival without detectable sequelae was similar, at 78% and 77%, respectively. The duration of therapy, 11.1 +/- 2.4 days (range 10 to 21 days) vs 11.9 +/- 3.9 days (range 10 to 21 days), and days to defervescence, 4.7 +/- 2.6 days (range 1 to 14 days) vs 5.6 +/- 2.9 days (range 2 to 17 days), were similar in the cefotaxime and standard therapy groups, respectively. No adverse drug reactions or side effects were noted in either group. Cefotaxime was found to be as safe and effective as standard therapy for the treatment of bacterial meningitis in children.