Prevalence of Chlamydia trachomatis and Mycoplasma pneumoniae in children with and without pharyngitis

The prevalence of Chlamydia trachomatis, Mycoplasma pneumoniae, group A beta-hemolytic streptococcus, and other treatable organisms was studied in children with and without pharyngitis. Children aged 2 to 12 years were evaluated between November 1985 and April 1986 in three family practice offices in the Salt Lake City area. Chlamydia trachomatis was not detected in the pharynx of any of the children studied. Mycoplasma pneumoniae was cultured from 5 percent of the 242 children studied, group A beta-hemolytic streptococcus from 30 percent, non-group A beta-hemolytic streptococcus from 5 percent, Hemophilus influenzae from 4 percent, and Staphylococcus aureus from 14 percent. The symptoms reported were not statistically associated with any organism isolated, and clinical signs of pharyngitis were associated only with the presence of group A beta-hemolytic streptococcus. Based on these results, management of pharyngitis in children should continue to be based on the detection and treatment of group A beta-hemolytic streptococcus.     

Protein components specifically associated with prespliceosome and spliceosome complexes.

We have carried out a systematic analysis of the protein composition of highly purified mammalian spliceosomes. We show that > 30 distinct proteins, including 20 previously unidentified components [designated spliceosome-associated proteins (SAPs)], are specifically associated with the spliceosome in a salt-resistant complex. In contrast to these spliceosome-specific proteins, we show that hnRNP proteins are not tightly associated with purified prespliceosome and spliceosome complexes. The splicing factor U2AF65, U1 snRNP-specific proteins, and several SAPs are present in the earliest prespliceosome complex (E). A set of 10 proteins is then added to the first ATP-dependent prespliceosome complex (A), and concomitantly, a significant decrease in the level of U2AF65 is observed. The fully assembled spliceosome is formed by the addition of 12 proteins in a reaction that requires ATP and both the 5' and 3' splice sites.     

The value of CT in determining potential instability of simple wedge-compression fractures of the lumbar spine.

PURPOSETo determine whether plain films alone are sufficient in the evaluation of stability of simple wedge-compression fractures of the lumbar spine.METHODSPlain films and CT scans of 53 consecutive patients seen during a 2-year period with lumbar spine fractures were retrospectively reviewed. Six readers blinded to the CT diagnosis independently read each patient''s plain films. Plain-film findings were scored on a five-point graded response scale using criteria proposed by Gehweiler and Daffner. In addition, a fracture was considered to be possibly unstable if there was involvement of more than one vertebral level or greater than 50% loss of anterior vertebral body height. CT findings represented the standard for comparison. CT scans were independently evaluated by three additional readers. Two-column involvement, middle-column involvement alone but with retropulsion, multiple-level involvement, or greater than 50% loss of vertebral height indicated potential instability.RESULTSFor 14 stable and 39 potentially unstable lumbar spine fractures, the pooled (mean) plain-film negative predictive value for detection of potentially unstable fractures was 0.62 (95% confidence interval, 0.53 to 0.70), with a sensitivity of 0.83 (95%, confidence interval; 0.78 to 0.87), and specificity of 0.80 (95% confidence interval, 0.70 to 0.87).CONCLUSIONPlain films are not adequate for determining stability of lumbar spine fractures.     

Role of cytochrome P450IIIA4 in the metabolism of the pyrrolizidine alkaloid senecionine in human liver

Studies were carried out to investigate the metabolism of senecionine by human liver microsomes and the role of human cytochrome P450IIIA4 in this process. Human liver microsomes metabolized senecionine to two major products, (+/-)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP) and senecionine N-oxide. The rates of product formation (DHP and senecionine N-oxide) varied widely with the microsomal samples tested. There was a 30-fold difference in DHP formation and a 25-fold difference in N-oxidation between the poorest metabolizer and the highest metabolizer of senecionine. The conversion of senecionine to DHP and senecionine N-oxide in human liver microsomes was markedly inhibited by the mechanism-based inactivators of P450IIIA4, gestodene and triacetyloleandomycin. Anti-P450IIIA4 IgG, at a concentration of 1 mg/nmol of P450, was found to inhibit completely the formation of DHP and senecionine N-oxide in human liver microsomes (HL101) having low activity toward senecionine. At 5 mg IgG/nmol P450, anti-P450IIIA4 inhibited 90 and 84% respectively of the formation of DHP and senecionine N-oxide in liver microsomes (HL110) with the highest activity toward senecionine. The formation of DHP or senecionine N-oxide was highly correlated with the amount of P450IIIA4 measured in the microsomes using polyclonal anti-P450IIIA4 IgG. The rate of DHP production also had a strong correlation with the rate of senecionine N-oxide formation (r = 0.999) and with the rate of nifedipine oxidation (r = 0.998). Our present studies provide evidence that P450IIIA4 is the major enzyme catalyzing the bioactivation (DHP formation) and detoxication (senecionine N-oxide formation) of senecionine in human liver.     

Effects of simplifying choice tasks on estimates of taste heterogeneity in stated-choice surveys

Researchers usually employ orthogonal arrays or D-optimal designs with little or no attribute overlap in stated-choice surveys. The challenge is to balance statistical efficiency and respondent burden to minimize the overall error in the survey responses. This study examined whether simplifying the choice task, by using a design with more overlap, provides advantages over standard minimum-overlap methods. We administered two designs for eliciting HIV test preferences to split samples. Surveys were undertaken at four HIV testing locations in San Francisco, California. Personal characteristics had different effects on willingness to pay for the two treatments, and gains in statistical efficiency in the minimal-overlap version more than compensated for possible imprecision from increased measurement error.     

Cognitive and neuroimaging predictors of instrumental activities of daily living.

Impaired ability to conduct daily activities is a diagnostic criterion for dementia and a determinant of healthcare services utilization and caregiver burden. What predicts decline in instrumental activities of daily living (IADLs) is not well understood. This study examined measures of episodic memory, executive function, and MRI brain volumes in relation to baseline IADLs and as predictors of rate of IADL change. Participants were 124 elderly persons with cognitive function between normal and moderate dementia both with and without significant small vessel cerebrovascular disease. Random effects modeling showed that baseline memory and executive function (EXEC) were associated with baseline IADL scores, but only EXEC was independently associated with rate of change in IADLs. Whereas hippocampal and cortical gray matter volumes were significantly associated with baseline IADL scores, only hippocampal volume was associated with IADL change. In a model including cognitive and neuroimaging predictors, only EXEC independently predicted rate of decline in IADL scores. These findings indicate that greater executive dysfunction at initial assessment is associated with more rapid decline in IADLs. Perhaps executive function is particularly important with respect to maintaining IADLs. Alternatively, executive dysfunction may be a sentinel event indicating widespread cortical involvement and poor prognosis.     

Molecular cloning and characterization of a Ca2+/calmodulin-insensitive adenylyl cyclase from rat brain.

Biochemical, immunological, and molecular cloning studies have suggested the existence of multiple forms of adenylyl cyclase (EC 4.6.1.1). An adenylyl cyclase cDNA clone (type II) was isolated from a rat brain library and found to encode a protein of 1090 amino acids that was homologous to but distinct from the previously described Ca2+/calmodulin-stimulated adenylyl cyclase from bovine brain. Expression of the type II cDNA in an insect cell line resulted in an increased level of adenylyl cyclase activity that was insensitive to Ca2+/calmodulin. Addition of activated Gs alpha protein to type II-containing membranes increased enzyme activity. The mRNA encoding the type II protein was expressed at high levels in brain tissue and at low levels in olfactory epithelium and lung. The existence of multiple adenylyl cyclase enzymes may provide for complex and distinct modes of biochemical regulation of cAMP levels in the brain.     

Leukopenia, neutropenia, and reduced hemoglobin levels in healthy American blacks

Hematologic profiles of 462 persons, mostly active-duty service members, were studied to determine whether hematologic differences between blacks and whites exist in a healthy population. Whites had significantly greater mean concentrations of leukocytes (6.73 vs 5.95 x 10(9)/L), neutrophils (3.96 vs 3.16 x 10(9)/L), and hemoglobin (153 vs 135 g/L for men, 147 vs 125 g/L for women). The mean differences were largely due to relatively symmetric shifts in the frequency distributions for these cell concentrations. No significant correlation was found between neutrophil count and morbidity from infection as measured by a standardized questionnaire. The use of separate hematologic reference values for blacks and whites should be considered.