Allergen-driven limiting dilution analysis of human IL-4 and IFN-gamma production in allergic rhinitis and clinically tolerant individuals

Difficulties in detecting human IL-4 synthesis in antigen-driven primary culture have led to widespread reliance on less physiologic approaches to T cell activation. Although there is general agreement of a Th2-like bias, the precise defects in cytokine responsiveness remain controversial. Analysis of cytokine protein production by fresh, unselected cell populations in response to cognate, antigen-driven stimulation remains an important goal. Here, limiting dilution analysis (LDA) was used to evaluate antigen-stimulated cytokine gene expression by fresh peripheral blood mononuclear cells (PBMC). PBMC from 19 grass pollen sensitive, allergic rhinitis subjects and normal, non-atopic controls were evaluated 1 month after natural reimmunization (the peak of the local grass pollen season). Surprisingly, highly atopic subjects and clinically non-allergic individuals exhibited virtually equivalent antigen-specific, CD4-dependent cytokine production in response to short-term culture with these common environmental antigens. As anticipated, pronounced increases in Th2-like activity were evident in the circulating immune repertoire of grass pollen sensitive individuals, leading to a median ratio of antigen-stimulated IFN-gamma:IL-4 frequencies of 117:1 among normal subjects versus 4:1 among those with allergic rhinitis (Mann-Whitney U-test, P = 0. 00067). This Th2-like bias reflected both a lower frequency of IFN-gamma-producing cells and a markedly increased frequency of IL-4-producing cells in the circulating grass-pollen specific repertoire of atopic donors. The observation that every atopic and normal subject produced IFN-gamma (+/-IL-4) following antigen re-stimulation argues that the decision as to whether allergy or (clinical) tolerance results, hinges not on a genetically determined capacity of whether allergen-reactive T cells can be stimulated in any given individual by chronic exposure to ubiquitous environmental antigens, but on the nature of the cytokine response that comes to dominate that individual's response.     

Onchocerca volvulus-mediated keratitis: cytokine production by IL-4-deficient mice

Corneal inflammation similar to human onchocercal keratitis can be induced in mice by subcutaneous immunization of a soluble extract of Onchocerca volvulus (OvAg) followed by direct injection of OvAg into the corneal stroma. Previous studies have shown that corneal pathology is associated with increased systemic and corneal Th2 cytokine expression and that IL-4 gene knockout (IL-4-/-) mice develop less severe or no O. volvulus-mediated keratitis. The current study examined the contribution of Th2 cytokines to the diminished OvAg-induced corneal immunopathology observed in IL-4-/- mice. IL-4-/- mice (129Sv x C57B1/6), wild-type F2 littermates (IL-4+/+), and C57B1/6 mice were sensitized by repeated subcutaneous immunization with OvAg. Ten days after the final immunization, mice were sacrificed, spleens were removed, and cells were incubated with OvAg. Cells from immunocompetent C57B1/6 and IL-4+/+ mice produced IL-4 and IL-5, but no IFN-gamma, whereas cells from IL-4-/- mice had elevated IFN-gamma and no IL-4. Interestingly, cells from these animals produced levels of IL-5 protein equivalent to those of C57B1/6 and IL-4+/+ mice. To determine cytokine production in corneas during the onset of onchocercal keratitis, OvAg-immunized mice were injected intracorneally with OvAg, and cytokine gene expression in the cornea was determined by RT-PCR. Temporal analysis of cytokine gene expression in corneas of immunocompetent mice showed that the Th2-associated cytokines IL-4, IL-5, IL-10, and IL-13 were produced within 1 day of intrastromal injection, with sustained elevations for 10 days. Maximal IFN-gamma mRNA levels were not detected until Day 10. This was in contrast to IL-4-/- mice in which IFN-gamma appeared at Day 1 and remained elevated for at least 10 days. Moreover, in corneas from IL-4-/- mice, all Th2 cytokines with the exception of IL-4 were up-regulated and expressed with kinetics similar to that of IL-4+/+ littermates. Histologically, corneas from IL-4-/- mice were less edematous and contained fewer eosinophils and other inflammatory cells than those from immunocompetent controls. As there was no difference in peripheral eosinophil levels, these data indicate that the diminished severity of onchocercal keratitis in IL-4-/- mice is not due to failure to develop systemic or local Th2 cytokine responses or to produce eosinophils, but that IL-4 may be involved in recruitment of eosinophils and other inflammatory cells into the corneal stroma.     

Phylogeny of species in the family Neisseriaceae isolated from human dental plaque and description of Kingella oralis sp. nov [corrected

Fourteen human periodontal isolates recovered from a purported Eikenella corrodens-selective medium containing 1 microgram of clindamycin per ml displayed biochemical traits which differed from those described for E. corrodens. These organisms were gram-negative rods which corroded agar. The isolates were oxidase positive and urease, indole, and esculin negative. They differed from E. corrodens in catalase, nitrate reduction, lysine decarboxylase, and ornithine decarboxylase activities. One isolate, strain UB-294, was presumptively identified as Kingella denitrificans. A second isolate, strain UB-204, differed from E. corrodens by being catalase positive and nitrate reduction negative. Twelve isolates, including strain UB-38T (T = type strain), were phenotypically similar to Kingella kingae except that they did not produce acid from maltose and were not beta-hemolytic. Essentially complete (1,480-base) 16S rRNA sequences were determined for strains UB-38T, UB-204, and UB-294 and the type strains of Neisseria animalis, Neisseria canis, Neisseria denitrificans, Neisseria elongata, Neisseria flavescens, Neisseria macaca, and Neisseria polysaccharea. These sequences were compared with the previously published sequences of six other species belonging to the family Neisseriaceae. On the basis of the results of the comparative sequence analysis, UB-294 was confirmed as a K. denitrificans strain, UB-204 was identified as a member of a new species which may belong in the genus Eikenella, and UB-38T was identified as a member of a new species of the genus Kingella, for which we propose the name Kingella oralis [corrected]. Since strain UB-204 was the only representative of a new species, it was not named.(ABSTRACT TRUNCATED AT 250 WORDS)     

Total anomalous pulmonary venous connection. Results of a small consecutive series

The surgical experience in 13 infants with total anomalous pulmonary venous connection (TAPVC) between 1987 and 1991 is reviewed. The age vary from 2 days to 35 months with a weight at intervention from 2.130 kg to 5.400 kg. The types of TAPVC were supracardiac in 4 patients, cardiac in 4, and infracardiac in 5. Seven patients (54%) were operated on in emergency. Cardiopulmonary bypass consisted of profound hypothermia and total circulatory arrest in 8 patients (60%) and continuous hypothermic bypass with low flow for the remaining 5 patients (40%). There was no operative death. The follow-up ranges from 21 to 58 months, mean 40 months. There was one reoperation. All the patients were asymptomatic and the height growth percentile is less than 5% in 20%, and the weight growth percentile is less than 5% in 30%. The early repair of infants born with TAPVC can be done with low morbidity with a good prospect on medium term follow-up.     

Trends in clinical dentistry skills observed by board examiners: a 15-year comparison

This study compares and analyzes the clinical performance of recent dental graduates over a 15-year period. A majority of the 981 board examiners, cumulatively surveyed, observed an increase in diagnosis/treatment planning and periodontal skills, and a decrease in operative and prosthodontic skills, while many other skills were performed at approximately the same level.     

Estimating net joint torques from kinesiological data using optimal linear system theory

Net joint torques (NJT) are frequently computed to provide insights into the motor control of dynamic biomechanical systems. An inverse dynamics approach is almost always used, whereby the NJT are computed from 1) kinematic measurements (e.g., position of the segments), 2) kinetic measurements (e.g., ground reaction forces) that are, in effect, constraints defining unmeasured kinematic quantities based on a dynamic segmental model, and 3) numerical differentiation of the measured kinematics to estimate velocities and accelerations that are, in effect, additional constraints. Due to errors in the measurements, the segmental model, and the differentiation process, estimated NJT rarely produce the observed movement in a forward simulation when the dynamics of the segmental system are inherently unstable (e.g., human walking). Forward dynamic simulations are, however, essential to studies of muscle coordination. We have developed an alternative approach, using the linear quadratic follower (LQF) algorithm, which computes the NJT such that a stable simulation of the observed movement is produced and the measurements are replicated as well as possible. The LQF algorithm does not employ constraints depending on explicit differentiation of the kinematic data, but rather employs those depending on specification of a cost function, based on quantitative assumptions about data confidence. We illustrate the usefulness of the LQF approach by using it to estimate NJT exerted by standing humans perturbed by support-surface movements. We show that unless the number of kinematic and force variables recorded is sufficiently high, the confidence that can be placed in the estimates of the NJT, obtained by any method (e.g., LQF, or the inverse dynamics approach), may be unsatisfactorily low.