Validation of crystal structure of 2-acetamidophenyl acetate: an experimental and theoretical study.

In this present study, we have determined the crystal structure of 2-acetamidophenyl acetate (2-AAPA) commonly used as influenza neuraminidase inhibitor, to analyze the polymorphism. Molecular docking and molecular dynamics have been performed for the 2-AAPA-neuraminidase complex as the ester-derived benzoic group shows several biological properties. The X-ray diffraction studies confirmed that the 2-AAPA crystals are stabilized by N-H···O type of intermolecular interactions. Possible conformers of 2-AAPA crystal structures were computationally predicted by ab initio methods and the stable crystal structure was identified. Hirshfeld surface analysis of both experimental and predicted crystal structure exhibits the intermolecular interactions associated with 2D fingerprint plots. The lowest docking score and intermolecular interactions of 2-AAPA molecule against influenza neuraminidase confirm the binding affinity of the 2-AAPA crystals. The quantum theory of atoms in molecules analysis of these intermolecular interactions was implemented to understand the charge density redistribution of the molecule in the active site of influenza neuraminidase to validate the strength of the interactions.Communicated by Ramaswamy H. Sarma.

Pharmacokinetics of single daily dose gentamicin in children with cancer.

PURPOSE: To study the pharmacokinetics of single daily dose (SDD) gentamicin in children with cancer. METHODS: Serum concentrations of gentamicin were prospectively measured at 0.5, 8, 16, and 24 hours after a single daily dose of gentamicin 6 mg/kg, given as a 30-minute infusion in 18 febrile children with cancer and a central venous catheter. Then the peak (0.5-hour) and 12-hour serum concentrations of gentamicin were prospectively measured after a SDD of 7 mg/kg during 73 febrile episodes in 54 pediatric cancer patients with suspected infections. The aim was to achieve a peak serum concentration of 15 to 20 microg/mL 10 times the minimum inhibitory concentration (MIC) for sensitive Pseudomonas strains, resulting in good bactericidal activity and a long post-antibiotic effect (PAE) after a SDD of gentamicin. RESULTS: The mean serum peak gentamicin concentration 30 minutes after the end of the infusion of 6 mg/kg was 13.3 +/- 4.0 microg/mL. The mean serum concentration 16 hours after the infusion was 0.3 +/- 0.2 microg/mL. The mean peak and 12-hour serum concentration after SDD of 7 mg/kg was 17.2 +/- 3.9 microg/mL and 0.9 +/- 0.7 microg/mL, respectively. The mean peak serum concentration after SDD of 7 mg/kg in children younger than 5 years of age (16.1 +/- 3.5 microg/mL ) was significantly lower than that of children over 5 years of age (18.2 +/- 3.9 microg/mL; P = 0.02). The desired peak serum concentration was achieved in 67% of children younger and 84% of those older than 5 years of age. CONCLUSION: Adequate peak serum concentrations of gentamicin in children may be obtained with a SDD of 7 mg/kg. Children younger than 5 years of age achieve lower peak serum gentamicin concentration after SDD of 7 mg/kg than those older than 5 years.

Growth in children undergoing bone marrow transplantation after busulfan and cyclophosphamide conditioning.

PURPOSE: The purpose of this study was to evaluate the effect of busulfan and cyclophosphamide (BUCY) as conditioning regimen for bone marrow transplantation (BMT) on growth of children following BMT. PATIENTS AND METHODS: Growth assessment was prospectively done in all 25 children who underwent BMT following BUCY conditioning from 1989 to 1994 at Children's Hospital of Philadelphia. The height and growth rates were expressed as standard deviation scores (SDS). The height SDS prior to BMT were compared with 1, 2, and 3 years post-BMT. The growth rate SDS 1 year and 2 years post-BMT were also compared. Pubertal children were excluded from the analysis of growth rate. Median age of patients was 7 years (range, 1.3-15 years). A total of 22/25 patients were transplanted for AML, and three patients had myelodysplastic syndrome. Equal numbers of patients had autologous and allogeneic transplants. Seven patients received corticosteroids for varying lengths of time. The pre-BMT height SDS (mean +/- SD) for the group was -0.4 +/- 1.3. The mean height SDS for 19 children at 1 year post-BMT was +/- 0.1 +/- 1.2 and for 10 children, 2 years post-BMT was -0.3 +/- 1.6. Seven children who were 3 years post-BMT had the mean height SDS of -0.2 +/- 1.5. There was no statistically significant difference between pre-BMT height SDS and 1 year post-BMT (p = 0.49) and 2 years post-BMT (p = 0.42). The mean growth rate at 1 year post-BMT was -0.1 +/- 2.7 and at 2 years post-BMT was -0.9 +/- 2.3. The difference was not statistically different (p = 0.15). Somatomedin-C (insulin growth factor 1, IGF-1) levels were normal in all 13 children tested at 1 year post-BMT. IGF binding protein (BP)-3 levels were done in 10 children at 1 year and were found to be normal in all. Thyroid function studies were done in all patients pre-BMT and 1 year post-BMT and were normal for all. Bone age assessment was appropriate for age in all 14 patients tested at 1 year post-BMT. CONCLUSIONS: There was no evidence of growth failure following BMT with BUCY conditioning in this group of patients.

Dysgenesis of thyroid is the common type of childhood hypothyroidism in environmentally iodine deficient areas of north India.

Forty-five children (28 girls and 17 boys; mean age 4.5 years) with hypothyroidism referred to us from January 1989 to November 1990 were evaluated prospectively for the pattern of hypothyroidism by hormone assays, scintiscan and urinary iodine estimation. Among the 6 children from non-endemic areas, athyreosis and/or hypoplasia were seen in 3, ectopia in 2 and dyshormonogenesis in 1. Of 39 children from moderate to severe environmentally iodine deficient regions, 18 (46%) had athyreosis and/or hypoplasia and 10 (26%) ectopic thyroid. Iodine deficiency was seen in 4, dyshormonogenesis in 4, secondary/tertiary hypothyroidism in 2 and thyroiditis in 1. The mean age of these children at the onset of symptoms was 1.4 years and at clinical presentation 4.5 years. There was significant growth retardation with 54% of children being below the 5th centile of Indian standards. There was no significant difference in the age at onset of symptoms and presentation, clinical features and bone age for the different types. The levels of serum total T4 were significantly low in dysgenesis (athyreosis, hypoplasia and ectopia, p < 0.001). Dysgenesis of the thyroid is the most common type of childhood hypothyroidism in iodine deficiency endemias. We postulate that severe iodine deficiency in the intrauterine and early neonatal period may lead to dysgenesis of the thyroid.