Oral beta2-agonist use by preschool children with asthma in East and Central Harlem, New York.

Although studies have documented underuse of controller medications and overuse of short-acting inhaled ss(2)-agonist among children with persistent asthma in disadvantaged communities, the persistence of oral ss(2)-agonist use in pediatric practice has not been studied since inhaled short-acting ss(2)-agonists became widespread. We describe medications used to treat asthma among children 3 to 5 years of age at 10 Head Start and other subsidized preschool centers in East and Central Harlem, New York City. We interviewed 149 parents/guardians of children who were identified as having probable asthma based on physician's diagnosis, persistent symptoms, hospitalization, and medication use. We classified 86 of the 149 children (58%) as having current persistent asthma. Only 15 of them (17%) were reported to have used controller medications at least 5 days/week in the last 4 weeks-only 2 of whom used inhaled corticosteroids. By contrast, 53 children (62%) used oral ss(2)-agonist in the last 4 weeks, often (72%) in conjunction with nebulized or inhaled short-acting ss(2)-agonist. Use of oral ss(2)-agonist was associated with more severe symptoms. This study documents the continued widespread use of oral ss(2)-agonist for treatment of children in a low-income community with high prevalence of asthma.     

Inhibition of ligand binding to g protein-coupled receptors by arachidonic acid

Arachidonic acid (AA), released in response to muscarinic acetylcholine receptor (mAChR) stimulation, previously has been reported to function as a reversible feedback inhibitor of the mAChR. To determine if the effects of AA on binding to the mAChR are subtype specific and whether AA inhibits ligand binding to other G protein-coupled receptors (GPCRs), the effects of AA on ligand binding to the mAChR subtypes (M₁, M₂, M₃, M₄, and M₅) and to the μ-opioid receptor, β₂-adrenergic receptor (β₂-AR), 5-hydroxytryptamine receptor (5-HTR), and nicotinic receptors were examined. AA was found to inhibit ligand binding to all mAChR subtypes, to the β₂-AR, the 5-HTR, and to the μ-opioid receptor. However, AA does not inhibit ligand binding to the nicotinic receptor, even at high concentrations of AA. Thus, AA inhibits several types of GPCRs, with 50% inhibition occurring at 3–25 μM, whereas the nicotinic receptor, a non-GPCR, remains unaffected. Further research is needed to determine the mechanism by which AA inhibits GPCR function.     

Antagonist binding properties of five cloned muscarinic receptors expressed in CHO-K1 cells

A family of five cholinergic muscarinic receptor genes (m1, m2, m3, m4, and m5) has recently been identified and cloned. In order to investigate the pharmacological properties of the individual muscarinic receptors, we have transfected each of these genes into Chinese hamster ovary cells (CHO-K1) and have established stable cell lines expressing each receptor. In the present study we have examined the antagonist binding properties of each muscarinic receptor. Antagonists were chosen that had previously been proposed to be selective for muscarinic receptor subtypes and included pirenzepine, AF-DX 116, methoctramine, dicyclomine, hexohydrodifenidol, hexahydrosiladifenidol, hexocyclium, and silahexocyclium. m1, m2, and m3 receptors express binding properties similar to those expected of high affinity pirenzepine-type receptors of cerebral cortex ("M1"), low affinity pirenzepine-type receptors of atria ("M2 cardiac type"), and the intermediate affinity pirenzepine-type receptors found in exocrine glands ("M2 glandular type"), respectively. The M1/M2 schema cannot readily accommodate the binding properties of the m4 and m5 receptors. Pirenzepine, methoctramine, and hexahydrosiladifenidol were the most selective agents for the m1, m2, and m3 receptors, respectively. None of the antagonists used in this study were uniquely selective for either the m4 or m5 receptors. The diverse binding profiles of individual cloned receptors and the widespread distribution of m1-m4 mRNAs indicate that radioligand binding studies performed on primary tissues may actually be assessing the composite properties of a heterogeneous mixture of muscarinic receptor subtypes.     

Biochemical characterisation of para-aminophenol-induced nephrotoxic lesions in the F344 rat

The acute biochemical effects of the nephrotoxin p-aminophenol (PAP) were studied in detail using a combination of conventional bioanalytical and ¹H-NMR spectroscopic methods. Dosing PAP (25–100 mg/kg) to male F344 rats resulted in a dose-related proximal nephropathy with consequent elevations in urinary enzymes, glucose, and urine total protein as shown by conventional methodology. ¹H-NMR spectroscopy at 400 MHz of urine from PAP-treated rats also revealed a characteristic glycosuria, with concomitant amino aciduria. The increased excretion of these compounds indicates functional defects in the proximal tubule and reduced solute reabsorption efficiency. In addition, ¹H-NMR urinalysis and conventional enzymatic analysis showed a dose-related lactic aciduria. Other changes detected by ¹H-NMR included a dose-related reduction in the excretion of citrate (confirmed by a conventional biochemical method) and an increase in the excretion of acetate. The degree of abnormalities shown by ¹H-NMR urinalysis agreed well with histopathological observations and conventional biochemical indices of nephrotoxicity. ¹H-NMR urinalysis therefore serves to highlight changes in the excretion of low MW urine components not routinely studied by conventional biochemical analysis.Abbreviations ALP alkaline phosphatase - APAP paracetamol - BUN blood urea nitrogen - GFR glomerular filtration rate - GOT glutamate oxaloacetate transaminase - LAP leucine aminopeptidase - LDH lactate dehydrogenase - MW molecular weight - NAG N-acetyl--D-glucosaminidase - PAP p-aminophenol - ppm parts per million - TMAO trimethylamine N-oxide - UFR urine flow rate     

Expression microdissection: operator-independent retrieval of cells for molecular profiling.

Tissue microdissection is an important method for the study of disease states. However, it is difficult to perform high-throughput molecular analysis with current techniques. We describe here a prototype version of a novel technique (expression microdissection) that allows for the procurement of desired cells via molecular targeting. Expression microdissection (xMD) offers significant advantages over available methods, including an increase in dissection speed of several orders of magnitude. xMD may become a valuable tool for investigators studying cancer or other disease states in patient specimens and animal models.     

The evolution of baboon endogenous type C virus: related sequences in the DNA of distant species

The cellular DNA of species distantly related to the baboon have been tested for the presence of sequences related to baboon endogenous type C virus. Hybrids between viral cDNA and cellular DNA were detected using very low stringency hydroxyapatite conditions. The results confirm and extend the observation that the related sequences are more conserved in African primates than in non-African primates. Our data suggest that this result is due to unusual conservation of viral sequences in the African primates. Our assay is sufficiently sensitive to detect distantly related sequences in mouse type C viruses and in other primate endogenous viruses, including both the type C virus isolated from macaques (MAC-1) and the type D virus isolated from langurs (LAD-1). However, using baboon viral cDNA, we cannot distinguish human DNA from the DNA of several non-primate mammalian species.