Reproducibility of food atopy patch tests over time in the general child population

Background  The atopy patch test (APT) is no longer an experimental method; it is increasingly being used as a standard diagnostic tool for the characterization of patients with aeroallergen- and food-triggered disorders. Some technical aspects of this test still remain to be answered. We aimed to study the reproducibility of this test over time in the general child population.
Methods  In a general population of 118 children, we investigated the reproducibility of duplicate APTs with four food allergens in their native form, which were repeated at set intervals from the first test: 7 days (group 1), 14 days (group 2), and 21 days (group 3).
Results  We observed very poor reproducibility on both sides of the back in all three studied subgroups. The reproducibility rates and Cohen's κ values did not improve when we did not consider the side of the back. There were no differences in the prevalence of atopy between the subjects with reproducible and nonreproducible APT results. All three groups studied showed no difference in the prevalence rates of atopy. There was no relationship between APT and skin prick test positivity for the same allergen. Questionnaire-derived data about previous food-related reactions did not help in the evaluation of the doubtful nonreproducible APT results with food allergens.
Conclusions  Our results show that the reproducibility of food APTs is poor and unsatisfactory over time, and there is an urgent need for the development of optimal, stable, and good-quality APT testing substances.     

Comparative study of four wound dressings on epithelization of partial-thickness wounds in pigs

Sixteen shallow wounds were inflicted in each of five Yorkshire white female piglets, 18-20 kg body weight, by a 2-cm diameter, fast-rotating abrasive disc. The injury is similar to a second-degree burn. The wounds were dressed with one of four dressings: Duoderm (Squibb), Op-Site (Smith & Nephew) [corrected], and collagen sponge, covered with either occlusive or semiocclusive polyurethane film (Datascope Corp.). The last two dressings were moistened with saline before application. The rate of epithelization by planimetric quantitation after 3 to 5 days was the same regardless of the dressing used, although the epithelium layer was thicker in wounds treated with Duoderm. Wounds dressed by either of the collagen sponge materials showed a better appearance when visually scored. Wounds dressed with Duoderm or Op-Site were often macerated; Duoderm's paste-like material remained on the wound and was difficult to remove without inflicting discomfort to the patient. Duoderm, and also Op-Site, adhered much more strongly to the intact skin than either type of collagen sponge dressing.     

Development of a "leak-proof," knitted Dacron vascular prosthesis

We have developed a technique to render knitted Dacron prostheses totally impervious to blood leak by impregnating the cloth with collagen. These grafts were prepared by the manufacturer, sterilized, and have an indefinite shelf life. The objective of this study was to determine whether collagen impregnation has a deleterious effect on surface thrombogenicity and graft healing. The infrarenal aortas of 30 mongrel dogs were replaced with 6 cm X 6 mm Dacron grafts (15 collagen-impregnated and 15 control). The collagen-impregnated prostheses were visibly indistinguishable from the control. After blood flow was restored, no interstitial bleeding occurred in the collagen grafts, in contrast to the control grafts that initially leaked profusely. When they recovered, the dogs were divided into three groups: group I (five collagen, five control), group II (five collagen, four control), and group III (five collagen, three control). The grafts were harvested at 3, 6, and 9 months, respectively. Retroperitoneal healing response, capsular thickness and adherence, completeness of neointimal healing, surface fibrinolytic activator activity, and sections taken for light and scanning electron microscopy were studied and compared in a blinded fashion. In a separate set of experiments, experimental and control grafts were compared for in vivo surface thrombogenicity. The healing data were identical in the experimental and control prostheses in all parameters. Of particular interest was that initial capsule adherence was better and surface thrombogenicity less in the collagen-impregnated prosthesis. We conclude that collagen impregnation of a knitted Dacron prosthesis has no deleterious effect for the term of observation of this experiment.     

Genetic polymorphism of CCR5 gene and HIV disease: The heterozygous (CCR5/Δccr5) genotype is neither essential nor sufficient for protection against disease progression

Homozygous (Δccr5/Δccr5) and heterozygous (CCR5/Δccr5) deletions in the β-chemokine receptor 5 (CCR5) gene, which encodes for the major co-receptor for macrophage-tropic HIV-1 entry, have been implicated in resistance to HIV infection and in protection against disease progression, respectively. The CCR5/Δccr5 genotype was found more frequently in long-term nonprogressors (LTNP) (31.0%) than in progressors (10.6%, p < 0.0001), in agreement with previous studies. Kaplan-Meier survival analyses showed that a slower progression of disease, i.e. higher proportion of subjects with CD4⁺ T cell counts >500/μl (p = 0.0006) and a trend toward a slower progression to AIDS (p = 0.077), was associated with the CCR5/Δccr5 genotype. However, when LTNP were analyzed separetely, no significant differences in CD4⁺ T cell counts (p = 0.12) and viremia levels (p = 0.65) were observed between the wild-type (69 % of LTNP) and the heterozygous (31.0 %) genotypes. Therefore, there are other factors which play a major role in determining the status of nonprogression in the majority of LTNP. Furthermore, there was no evidence that the CCR5/Δccr5 genotype was associated with different rates of disease progression in the group of progressors. Taken together, these results indicate that the CCR5/Δccr5 genotype is neither essential nor sufficient for protection against the progression of HIV disease.     

HIV-1 p24 antigen is a significant inverse correlate of CD4 T-cell change in patients with suppressed viremia under long-term antiretroviral therapy

An HIV-1 p24 antigen test involving signal amplification-boosted ELISA of heat-denatured plasma was evaluated prospectively in 55 patients whose viral RNA in plasma had previously been suppressed for at least 6 months under antiretroviral combination therapy. During a median follow-up of 504 days, CD4 counts increased by a median of 62 cells per year. By univariate and multivariate linear regression analysis, the level of p24 antigen as expressed by the absorbance/cutoff ratio was a significant inverse correlate of both the CD4 count in a sample (p =.013) and its annual change in a patient (p <.0001). The p24 antigen retained significance even among 48 individuals whose HIV-1 RNA, apart from occasional blips, remained below 400 copies/mL. Batch-wise retesting of 70 samples from 5 such patients with a further improved procedure showed measurable p24 antigen in all but 1 sample and an inverse correlation with both the CD4 count (p =.0331) and percentage (p <.0001), thus confirming the prospectively generated data. Comparison of p24 antigen and HIV-1 RNA concentrations indicate that the p24 antigen detected in these samples is not associated with viral RNA-containing particles and may originate from other compartments of virus expression.     

Localization of endogenous galactoside-binding lectin during morphogenesis ofXenopus laevis

Summary A monoclonal antibody has been produced againstXenopus laevis galactoside-binding neural-creststage lectin. This antibody inhibits lectin-mediated hemagglutination. Using this antibody in conjunction with immunohistochemical techniques, lectin deposition has been studied in embryos and tadpoles at different stages of morphogenesis, from initial neural crest migration, up to the formation of a swimming tadpole. Lectin levels change during development in different regions of the embryo and tadpole, decreasing in migratory cells, and increasing in sites where cells become more adhesive to one another. The results suggest that galactoside-binding lectins may be an important class of cellular adhesion molecules during these stages of development.     

Effect of long-term sympathectomy on the arterial wall in rabbits and rats

The effect of chemical sympathectomy with 6-hydroxydopamine (6-OH-DA) on collagen formation in the aortic wall was investigated in rabbits and rats. Eight weeks after 6-OH-DA treatment of rabbits, there was a significant increase an collagen content in aortas and histologic changes in the elastic elements within the media. The possibility of a direct effect of 6-OH-DA on connective tissue formation was investigated in a subsequent experiment in rats. The rates of collagen synthesis and prolyl hydroxylase activity (PHA) were determined in aortas and in the fibrotic granuloma around subcutaneously implanted polyvinylalcohol sponges. Rates of collagen synthesis and PHA were significantly increased in the aortas of 6-OH-DA treated rats, but not in fibrotic granuloma, confirming the changes seen in the aorta of rabbits and suggesting that 6-OH-DA does not directly affect collagen synthesis. We conclude that the sympathetic nervous system influences the metabolic activity of the aorta. Our data indicate that when the aortic wall is deprived of adrenergic nervous stimulation, changes occur which resemble those seen in natural aging of the aorta. It is plausible to assume that such a metabolic derangement in the vessel wall will make these vessels more vulnerable to additional stresses.