Astrovirus-associated gastroenteritis in children.

In a small astrovirus-associated outbreak of gastroenteritis in a ward of a local children's hospital two out of five children with symptoms excreted astrovirus particles. No astrovirus particles were found in faeces from the remaining asymptomatic child, and no other viral or bacterial pathogens were found in any of the children. Virus excretion persisted for only a few days. Rising antibody titres to the astrovirus particles were demonstrated in one child, and IgM was also demonstrated in this patient's serum.     

Drug discrimination training during chronic drug treatment affects the development of tolerance

The purpose of this experiment was to evaluate the extent to which continued drug discrimination training during chronic drug treatment affects the development of tolerance. Rats were trained to discriminate distilled water from 0.75 mg/kg amphetamine in a two-lever drug discrimination task. Two groups were then given a chronic drug regimen of 13 daily injections of either distilled water or 10 mg/kg amphetamine. Drug discrimination training was continued for half of each chronic drug group. Tolerance was apparent only in the group that was not trained during the chronic amphetamine treatment. The data support the conclusion that continued training throughout the chronic drug treatment provides the opportunity for reinforced correct responding as both nondrug- and drug-cue states are gradually shifted by the chronic drug regimen.     

Application of potassium thiocyanate as a destaining agent for confirming the specificity of viral immunofluorescence.

A study was made of the destaining effects of various agents on measles-infected monolayers which were stained by the indirect method of immunofluorescence. It was found that KSCN, a chaotropic agent, gave the required destaining but was nonspecific in its action, removing antigen as well as adsorbed immunoglobulins. By using a KSCN-EDTA destaining solution, it was shown that two sequential restainings of infected monolayers were possible, which permitted the demonstration of the specificity of the observed immunofluorescence. The technique may be of particular use with clinical specimens in which relatively few cells give immunofluorescence and when the specificity of this fluorescence is questioned.     

An outbreak of food-borne gastroenteritis in two hospitals associated with a Norwalk-like virus.

Two connected outbreaks of gastroenteritis in separate hospitals associated with a small round structured virus morphologically indistinguishable from the Norwalk virus are described. The virus was most probably introduced on chicken sandwiches prepared by a member of the kitchen staff who was incubating the disease.     

Predominant usage of the proximal poly(A) site in alpha mRNAs is not intrinsic to the 3' termini

The maturation of IgM-expressing B cells to IgM-secreting plasma cells is associated with both an increase in mu mRNA and the ratio of secreted to membrane forms of mu mRNA. In contrast, previous studies demonstrated that in vitro the secreted form of alpha mRNA (alpha s mRNA) predominates regardless of the stage of B cell differentiation. The present study demonstrates that alpha s mRNA predominates in both B cells derived from the germinal centers of murine Peyer's patches and in the functional IgA memory population, suggesting that in vitro events accurately represent the generation of a secretory IgA response in vivo. Although the predominant usage of the alpha s poly(A) site is due to RNA processing, it does not depend on either the alpha s poly(A) site, the 3' splice site associated with the exon encoding the membrane exon of IgA (alphaM) or the alphaM poly(A) sites. Analysis of the sequence of the intron between the alpha s terminus and alphaM (alpha s- alphaM intron) demonstrates the existence of several potential regulatory elements. Furthermore, the effects of deletions within the alpha s-alphaM intron on 3' terminus usage demonstrate that the predominant usage of the proximal terminus is not strictly dependent on the length of the intron. Together with previous work, these observations support the idea that choice of 3' terminus for all Ig heavy chain genes is regulated by a similar mechanism, but specific sequences within a heavy chain gene can impinge upon that mechanism.      

Vulvovaginal-swab or first-catch urine specimen to detect Chlamydia trachomatis in women in a community setting?

Screening for chlamydia in women is widely recommended. We evaluated the performance of two nucleic acid amplification tests for detecting Chlamydia trachomatis in self-collected vulvovaginal-swab and first-catch urine specimens from women in a community setting and a strategy for optimizing the sensitivity of an amplified enzyme immunoassay on vulvovaginal-swab specimens. We tested 2,745 paired vulvovaginal-swab and urine specimens by PCR (Roche Cobas) or strand displacement amplification (SDA; Becton Dickinson). There were 146 women infected with chlamydia. The assays detected 97.3% (95% confidence interval [CI], 93.1 to 99.2%) of infected patients with vulvovaginal-swab specimens and 91.8% (86.1 to 95.7%) with urine specimens. We tested 2,749 vulvovaginal-swab specimens with both a nucleic acid amplification test and a polymer conjugate-enhanced enzyme immunoassay with negative-gray-zone testing. The relative sensitivities obtained after retesting specimens in the negative gray zone were 74.3% (95% CI, 62.8 to 83.8%) with PCR and 58.3% (95% CI, 46.1 to 69.8%) with SDA. In community settings, both vulvovaginal-swab and first-catch urine specimens from women are suitable substrates for nucleic acid amplification tests, but enzyme immunoassays, even after negative-gray-zone testing, should not be used in screening programs.