Apical cytoplasm

About: Apical cytoplasm is a research topic. Over the lifetime, 1080 publications have been published within this topic receiving 36131 citations.

Ultrastructural, Immunofluorescence, and RNA Evidence Support the Hypothesis of a “New” Virus Associated With Kawasaki Disease

Abstract: Kawasaki disease (KD) is a systemic vasculitis of young childhood that most significantly affects the coronary arteries. Although fatality rates are relatively low in countries attuned to the signs and symptoms and thus the diagnosis, the worldwide mortality and morbidity rates are unknown. Although the cause is unknown, clinical and epidemiologic data support the hypothesis of a ubiquitous etiologic agent that likely causes an inconsequential respiratory infection in the vast majority of children but disseminates and results in KD in a subset of children who are genetically predisposed [1]. An antigen-driven IgA immune response was detected in the walls of coronary and other arteries in the weeks following the onset of illness, leading to the hypothesis that the etiologic agent is microbial [2]. The beneficial or deleterious effect of the IgA antibodies remains to be ascertained. Synthetic versions of the IgA antibodies detect intracytoplasmic inclusion bodies (ICI) consistent with aggregates of viral protein and RNA in the apical region of ciliated epithelial cells of predominantly mid-sized bronchi of 85% of children with fatal KD, but not of infant controls [3–5]. With experience, the ICI can also be identified by light microscopy in hematoxylin-eosin stain sections. Cytoplasmic inclusions can be seen in a variety of virus and bacterial infections. They can also result from overproduced or misfolded aggregates of human proteins (ie, “aggresomes”[6]) in chronic neurodegenerative diseases such as Alzheimer's [7]. A primary feature of aggresomes is that they are surrounded by an intermediate filament “cage” [7]. Bacterial inclusion bodies contain bacterial forms that reflect their life cycle [8], in contrast to KD ICI, which are homogeneous. To determine whether the ICI seen in KD have a cage characteristic of an aggresome, we performed colocalization experiments using KD synthetic antibody plus an antibody to human cytokeratin, the intermediate filament present in bronchial epithelium [9]. To determine the nature of the RNAs in the apical cytoplasm of bronchial epithelium containing ICI, we performed laser-capture microdissection, isolated RNA, and synthesized and sequenced complementary DNA (cDNA) using high-throughput methods. We performed real-time reverse transcription–polymerase chain reaction (RT-PCR) for selected genes on lung RNA from KD patients and infant controls. We analyzed the bronchial epithelium of formalin-fixed, non–paraffin embedded lung tissue from autopsies of 3 KD patients by transmission electron microscopy (TEM) to determine if any microbial forms could be observed in specimens containing ICI.

Interferon-gamma gene and protein are spontaneously expressed by the porcine trophectoderm early in gestation.

Abstract: The nature and the source of the antiviral activity found in the reproductive tract of pregnant gilts early in gestation were analyzed. Two antigenically distinct antiviral activities were found in uterine flushings and in supernatants of conceptus-conditioned culture medium between days 12 and 20 of gestation, using Madin Darby bovine kidney cells and vesicular stomatitis virus as a challenge in the antiviral bioassay. One component was antigenically identified as interferon-gamma (IFN-gamma). Northern blot analysis of conceptus poly(A)+ RNA with a human IFN-gamma cDNA probe revealed two mRNA of 1.3 and 1.4 kb. In addition, immunoprecipitation of metabolically labeled conceptus secretory proteins with an antiserum raised against purified porcine rIFN-gamma resulted in four bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with molecular mass 18.5 to 24.5 kDa. Pre-electrophoresis incubation of the immunoprecipitate with glycopeptidase F, which removes N-linked carbohydrates, yielded a single band of 16.5 kDa. Finally, staining of ultrathin sections by indirect immunofluorescence using the same antiserum to rIFN-gamma revealed that all cells of extra-embryonic trophectoderm contained intensely fluorescent granules in their apical cytoplasm. Neither endoderm nor embryonic cells stained positive. These results clearly show that IFN-gamma, known so far as a T or NK cell-derived lymphokine, is spontaneously and intensively secreted by the porcine trophectoderm, an embryonic tissue not related to the hematopoietic lineage. They also suggest that the implanting conceptus, at least in the porcine species, could play an active role in immune interactions with the mother.

Differential localization of villin and fimbrin during development of the mouse visceral endoderm and intestinal epithelium.

Abstract: The apical surface of transporting epithelia is specially modified to absorb nutrients efficiently by amplifying its surface area as microvilli. Each microvillus is supported by an underlying core of bundled actin filaments. Villin and fimbrin are two actin-binding proteins that bundle actin filaments in the intestine and kidney brush border epithelium. To better understand their function in the assembly of the cytoskeleton during epithelial differentiation, we examined the pattern of villin and fimbrin expression in the developing mouse using immunofluorescence and immunoelectron microscopy. Villin is first detected at day 5 in the primitive endoderm of the postimplantation embryo and is later restricted to the visceral endoderm. By day 8.5, villin becomes redistributed to the apical surface in the visceral endoderm, appearing in the gut at day 10 and concentrating in the apical cytoplasm of the differentiating intestinal epithelium 2–3 days later. In contrast, fimbrin is found in the oocyte and in all tissues of the early embryo. In both the visceral endoderm and gut epithelium, fimbrin concentrates at the apical surface 2–3 days after villin; this redistribution occurs when the visceral endoderm microvilli first contain organized microfilament bundles and when microvilli first begin to appear in the gut. These results suggest a common mechanism of assembly of the absorptive surface of two different tissues in the embryo and identify villin as a useful marker for the visceral endoderm.

Ultrastructure of human labial salivary glands. III. Myoepithelium and ducts

Abstract: Myoepithelial cells were present between the basal lamina and the acinar secretory cells of human labial salivary glands. In form and disposition, they resembled myoepithelial cells in the major salivary glands. Many of these cells possessed single cilia on their upper surfaces. Such cilia occasionally extended into invaginations of the overlying secretory cell. The intercalated ducts were variable in occurrence. Their epithelium ranged from columnar to squamous, and showed few signs of secretory activity. Few intralobular ducts possessed basal striations. While mitochondria were abundant in non-striated cells, they were randomly disposed in both basal and apical cytoplasm, and the basal plasmalemma showed only occasional infoldings. The paucity of true striated ducts in labial salivary glands may be responsible for the high concentration of sodium and chloride in unstimulated labial gland salivary secretions.