Ceftazidime pharmacokinetics in preterm infants: effect of postnatal age and postnatal exposure to indomethacin.

1. The effects of postnatal age and postnatal exposure to indomethacin on the pharmacokinetic parameters of ceftazidime (CAZ) were investigated in 23 preterm infants (gestational age 28.7 +/- 1.7 weeks; weight 1086 +/- 311 g) on day 3 and day 10 after birth. 2. CAZ (25 mg kg-1) was administered by intravenous bolus injection. Blood samples were drawn from an arterial catheter at 0, 0.5, 1, 2, 4, 8, and 12 h after the dose and CAZ concentrations in serum were determined by h.p.l.c. CAZ pharmacokinetics followed a one-compartment open model. 3. The glomerular filtration rate (GFR) of all infants was studied by means of the 24 h continuous inulin infusion technique. 4. The total body clearance of CAZ (34.7 +/- 9.2 vs 50.6 +/- 19.6 ml h-1, P < 0.05; 30.7 +/- 5.9 vs 41.6 +/- 9.0 ml h-1 kg-1, P < 0.05) and GFR (0.72 +/- 0.11 vs 0.91 +/- 0.15 ml min-1, P < 0.05) increased, whereas the apparent volume of distribution (425 +/- 147 vs 352 +/- 108 ml, P < 0.05; 363 +/- 59 vs 292 +/- 44 ml kg-1, P < 0.005) and the elimination half-life (8.7 +/- 2.8 vs 5.0 +/- 0.9 h, P < 0.005) decreased significantly between day 3 and day 10 after birth. Clearance of CAZ increased with increasing GFR (r = 0.81, P < 0.001). 5. In infants with postnatal exposure to indomethacin the changes in CAZ pharmacokinetics were markedly reduced. 6. These results indicate that the dosage regimen of CAZ should be adjusted after the first week of life except in infants who were postnatally exposed to indomethacin.     

RSV-induced bronchiolitis but not upper respiratory tract infection is accompanied by an increased nasal IL-18 response

The aim of this study was to investigate potential differences in the local nasal immune response between bronchiolitis and upper respiratory tract infection induced by respiratory syncytial virus (RSV). Nasal brush samples were obtained from 14 infants with RSV bronchiolitis and from 8 infants with RSV upper respiratory tract infection. The samples were taken during infection (acute phase) and 2-4 weeks later (convalescent phase). Cytospin preparations were stained immunohistochemically for T cells, macrophages, and eosinophils. Staining also took place for intercellular adhesion molecule-1 (ICAM-1), T-helper 1 (Th1)-like (interleukin-12 [IL-12], interferon-gamma [IFN-gamma]), Th2-like (IL-4, IL-10), and proinflammatory cytokines (IL-6, IL-8, IL-18). During both RSV-induced bronchiolitis and upper respiratory tract infection, cellular inflammation was observed. This was characterised by an increase in the numbers of nasal macrophages, which tended to be higher in bronchiolitis than in upper respiratory tract infection. Numbers of T lymphocytes and ICAM-1 positive cells increased during both bronchiolitis and upper respiratory tract infection. There were no differences between numbers in the groups. Interestingly, a distinct nasal proinflammatory cytokine response was observed in RSV-induced bronchiolitis. This is characterised by an increase in the number of IL-18 positive cells. This increase is specific for bronchiolitis, as a similar increase could not be detected in RSV-induced upper respiratory tract infection. Numbers of IL-6 and IL-12 positive cells were higher in both bronchiolitis and upper respiratory tract infection, and there were no differences between the groups. By contrast, the number of IL-8, IFN-gamma, IL-4, and IL-10-positive cells remained constant. In conclusion, clear differences were found in nasal immune responses of children with RSV-induced upper respiratory tract infection or bronchiolitis. The induction of a strong IL-18 response was typical for bronchiolitis, as this could not be observed in RSV-induced upper respiratory tract infection, and could explain the eosinophilia that is observed frequently during bronchiolitis.     

Respiratory syncytial virus infections in children admitted to the intensive care unit

During the winter of 1986-1987, 64 children with respiratory syncytial virus (RSV) infection were admitted to our hospital. The diagnosis was made by direct immunofluorescent antibody technique. Twenty-three children (36%) needed intensive care treatment. Nearly 11 (52%) had a preexisting disease state, identified as a risk factor i.e., prematurity (n = 8), bronchopulmonary dysplasia (n = 2), congenital heart disease (n = 1). Twelve patients (50%) were intubated and ventilated. Conditions for intubation and ventilation were repetitive apnea with or without bradycardia (n = 4), clinical deterioration (n = 3) or hypercarbia (n = 5). Seventy-five percent of the patients who needed intensive care management were under three months of age compared to 34% of the children who were admitted to the clinical ward. The mean age for ventilated patients was 7.9 weeks. The mean duration of ventilation was 5.5 days. Volume controlled ventilation was initially applied to all patients. Pulmonary complications (atelectasis, pneumonia, pneumothorax or adult respiratory distress syndrome) were present in 15 (65%) IC patients. Nine (39%) of them also had symptoms of inappropriate antidiuretic hormone secretion (IADHS). Only two patients had symptoms of IADHS and two others had convulsions. Three children (5%) died as a result of respiratory insufficiency. Two of these infants belonged to the risk group.     

Respiratory tract disease in systemic lupus erythematosus.

Respiratory tract involvement is common in adults with systemic lupus erythematosus (SLE). Although SLE in children usually follows a more severe course than in adults, there are few reports on pulmonary disease and lung function in children with SLE. We performed lung function tests and chest x ray examinations in eight children with SLE (mean age 11.1 years), three of whom presented with pulmonary symptoms. A high prevalence of lung involvement was found, including interstitial or localised infiltrations, pleural effusion, a restrictive impairment of lung function, and dysfunction of the diaphragm. Three patients required artificial ventilation. Two main mechanisms of ventilatory impairment seem to occur in children with SLE: firstly, acute interstitial pneumonia, which rapidly improves on treatment with steroids, and, secondly, restriction of lung volume, mainly due to respiratory muscle weakness.     

Oligoclonal T cell proliferative disorder in combined immunodeficiency

Oligoclonal lymphoid proliferations may occur in immunocompromised patients and in the elderly. So far these proliferations have been shown to be of B cell origin. We describe a patient with a combined immunodeficiency, characterized by profound hypogammaglobulinemia and the initial absence of T lymphocytes in the peripheral blood (PB). From the age of 4 yr CD3+ T cells appeared in PB in rising numbers. These cells mainly expressed the CD4-/CD8+ phenotype (CD4/CD8 ratio: 0.1). Despite the emergence of T lymphocytes no proliferation of PB mononuclear cells could be induced with phytohemagglutinin, concanavalin A, or pokeweed mitogen. Between the ages of 4 and 6 yr the patient gradually developed hepatosplenomegaly and an interstitial pulmonary infiltrate of unknown origin, necessitating biopsies of both liver and lung. Infiltrates consisting of CD8+ T lymphocytes were found in the liver as well as the lung. CD8+ T cells were also abundant in the bronchoalveolar lavage fluid. Southern blot analysis of mononuclear cells from PB and of a lung biopsy specimen was performed to investigate if a clonal T cell population was involved. Analysis of the T cell receptor beta genes revealed that at least three expanded T cell clones were present in PB, one of which had invaded the lung. Thus far, i.e. 2 yr after the initial detection of clonal T cell receptor beta gene rearrangements, there have been no clinical or histologic signs of malignant behavior. We conclude that this combined immunodeficiency patient has a benign oligoclonal T cell lymphoproliferative disorder. Similar proliferations might well occur in other immunodeficiency states, whether primary or acquired.     

Vitamin B12 absorption in cystic fibrosis

Vitamin B12 absorption was measured in 30 patients with cystic fibrosis by means of the urinary excretion method and found to be impaired, i.e. less than 10%, in 25. The mean urinary excretion amounted to 4.7 +/- 0.8%. In all patients vitamin B12 absorption improved by the addition of trypsin (18.9 +/- 2.1%). Addition of the vitamin B12 analogue cobinamide, which prevents vitamin B12-binding by R-binders, raised the vitamin B12 absorption to 15.0 +/- 2.2%. A further improvement was obtained by the simultaneous addition of cobinamide and trypsin, 18.2 +/- 2.6%, the same value as with trypsin alone. Assuming that cobinamide addition was effective in suppressing all R-binder activity, the additional effect of trypsin suggests a second, stimulatory function of trypsin on vitamin B12 absorption, separate from R-binder-inactivation. In 5 patients only marginal improvement of vitamin B12 absorption was gained by the addition of either trypsin or cobinamide. The deficient serum vitamin B12 (110 pmol/l) in one of them indicates that the normal pancreas-substitution therapy not always implies sufficient restoration of vitamin B12 absorption.     

Elevated serum vitamin B12 in cystic fibrosis

In 62 patients with cystic fibrosis the serum vitamin B12 concentration ranged from 160-2600 pmol/l with a mean of 1 105 pmol/l. Both vitamin B12-binding proteins in the serum, transcobalamin II and R-binders, carried increased amounts of vitamin B12, but showed relatively normal levels of unsaturated vitamin B12-binding capacity. This combination is rather typical for hepatic dysfunction, although the recurrent pulmonary infections might exert an upward effect on plasma R-binder concentration through increased turnover of myeloid cells. A significant positive correlation between transcobalamin II-vitamin B12 and serum alkaline phosphatase suggests that transcobalamin II-bound vitamin B12 might be an early indicator of focal biliary cirrhosis, which is known to occur in these patients.