The sld genetic defect: two intronic CA repeats promote insertion of the subsequent intron and mRNA decay.

The autosomal recessive mutation, sld, attenuates mucous cell expression in murine sublingual glands with corresponding effects on mucin 19 (Muc19). We conducted a systematic study including genetic mapping, sequencing, and functional analyses to elucidate a mutation to explain the sld phenotype in neonatal mice. Genetic mapping and gene expression analyses localized the sld mutation within the gene Muc19/Smgc, specifically attenuating Muc19 transcripts, and Muc19 knock-out mice mimic the sld phenotype in neonates. Muc19 transcription is unaffected in sld mice, whereas mRNA stability is markedly decreased. Decreased mRNA stability is not due to a defect in 3'-end processing nor to sequence differences in Muc19 transcripts. Comparative sequencing of the Muc19/Smgc gene identified four candidate intronic mutations within the Muc19 coding region. Minigene splicing assays revealed a novel splicing event in which insertion of two additional repeats within a CA repeat region of intron 53 of the sld genome enhances retention of intron 54, decreasing the levels of correctly spliced transcripts. Moreover, pateamine A, an inhibitor of nonsense-mediated mRNA decay, inhibits degradation of aberrant Muc19 transcripts. The mutation in intron 53 thus enhances aberrant splicing leading to degradation of aberrant transcripts and decreased Muc19 message stability, consistent with the sld phenotype. We propose a working model of the unique splicing event enhanced by the mutation, as well as putative explanations for the gradual but limited increase in Muc19 glycoprotein expression and its restricted localization to subpopulations of mucous cells in sld mice during postnatal gland development.

Ovarian frozen section diagnosis: use of whole-slide imaging shows excellent correlation between virtual slide and original interpretations in a large series of cases.

CONTEXT: Whole-slide images (WSI) are a tool for remote interpretation, archiving, and teaching. Ovarian frozen sections (FS) are common and hence determination of the operating characteristics of the interpretation of these specimens using WSI is important. OBJECTIVES: To test the reproducibility and accuracy of ovarian FS interpretation using WSI, as compared with routine analog interpretation, to understand the technology limits and unique interpretive pitfalls. DESIGN: A sequential series of ovarian FS slides, representative of routine practice, were converted to WSI. Whole-slide images were examined by 2 pathologists, masked to all prior results. Correlation characteristics among the WSI, the original, and the final interpretations were analyzed. RESULTS: A total of 52 cases, consisting of 71 FS slides, were included; 34 cases (65%) were benign, and 18 cases (35%) were malignant, borderline, and of uncertain potential (9 [17%], 7 [13%], and 2 [4%] of 52 cases, respectively). The correlation between WSI and FS interpretations was 96% (50 of 52) for each pathologist for benign versus malignant, borderline, and uncertain entities. Each pathologist undercalled 2 borderline malignant cases (4%) as benign cysts on WSI. There were no overcalls of benign cases. Specific issues within the benign and malignant groups involved endometriosis versus hemorrhagic corpora lutea, and granulosa cell tumor versus carcinoma, respectively. CONCLUSIONS: The correlation between original FS and WSI interpretations was very high. The few discordant cases represent recognized differential diagnostic issues. Ability to examine gross pathology and real-time consultation with surgeons might be expected to improve performance. Ovarian FS diagnosis by WSI is accurate and reproducible, and thus, remote interpretation, teaching, and digital archiving of ovarian FS specimens by this method can be reliable.

Immunohistochemical assessment of fractalkine, inflammatory cells, and human herpesvirus 7 in human salivary glands.

Human fractalkine (CX3CL1), a delta-chemokine, is implicated in the mediation of multiple cell functions. In addition to serving as a chemotactic factor for mononuclear cell subtypes, membrane-bound fractalkine may promote viral infection by interacting with virions that encode putative fractalkine-binding proteins. Fractalkine expression in normal epithelial tissues studied to date is either constitutive or is upregulated with inflammation. In salivary glands, the expression of fractalkine is unknown. Moreover, salivary glands are a major site for the persistent and productive infection by human herpesvirus (HHV)-7, which encodes two putative fractalkine-binding gene products, U12 and U51. Surprisingly, the cellular distribution of HHV-7 in major salivary glands has not been explored. We therefore determined by immunohistochemistry the cellular localization of fractalkine in three different salivary glands: parotid, submandibular, and labial glands. Fractalkine expression was highly variable, ranging from high to undetectable levels. We further examined the association of fractalkine with inflammatory cell infiltration or HHV-7 infection of salivary epithelial cells. Inflammatory cells were always adjacent to epithelial cells expressing fractalkine, consistent with a function of fractalkine in inflammatory cell recruitment and/or retention in salivary glands. In contrast, HHV-7-infected epithelial cells did not always express fractalkine, suggesting that fractalkine may not be an absolute requirement for viral entry.