CNS myelin and sertoli cell tight junction strands are absent in Osp/claudin-11 null mice.

Oligodendrocyte-specific protein (OSP)/claudin-11 is a recently identified transmembrane protein found in CNS myelin and testis with unknown function. Herein we demonstrate that Osp null mice exhibit both neurological and reproductive deficits: CNS nerve conduction is slowed, hindlimb weakness is conspicuous, and males are sterile. Freeze fracture reveals that tight junction intramembranous strands are absent in CNS myelin and between Sertoli cells of mutant mice. Our results demonstrate that OSP is the mediator of parallel-array tight junction strands and distinguishes this protein from other intrinsic membrane proteins in tight junctions. These novel results provide direct evidence of the pivotal role of the claudin family in generating the paracellular physical barrier of tight junctions necessary for spermatogenesis and normal CNS function.

A comparison of the effect of growth factors on intestinal function and structure in short bowel syndrome.

BACKGROUND/PURPOSE: Epidermal growth factor (EGF) and Insulin like growth factor-1 (IGF-1) increase substrate absorption beyond the normal adaptive response after massive small bowel resection in the rat. However, the mechanism for this response is unknown. This study was designed to evaluate the ultrastructural features of the rat small intestine epithelium after exposure to EGF and IGF-1 and correlate any changes with a possible hypothesis regarding the mechanism for the increased absorption. METHODS: Male Sprague-Dawley rats underwent an 80% small bowel resection and jejunostomy tube placement. Seven days later an osmotic pump placed subcutaneously and containing the test substance was connected to the jejunostomy tube. The rats were assigned to one of three groups: group 1 received normal saline (control, n = 5); group 2 received EGF at 150 microg/kg/d (n = 5); and group 3 received IGF-1 at 20 mg/kg/d (n = 5). After a 14-day infusion, a portion of mid-small bowel was resected for light and electron microscopic evaluation from each of the animals. The following features were compared between the groups: villous length, crypt length, villous-crypt ratio, villi per millimeter mucosa, goblet cell distribution, eosinophilic infiltrates, number and distribution of organelles, length of microvilli, and completeness of microvillous surface. RESULTS: Ultrastructurally, the bowel epithelium was well preserved in all animals. There were no objective ultrastructural differences between the controls and growth factor-exposed animals. The mean villous-crypt ratio, mean number of villi per millimeter of mucosa (cross section), and mean microvillous height were not significantly different among the groups. However, there was a subjective increase in the number of lysosomes in the enterocytes exposed to EGF and IGF-1. CONCLUSIONS: Administration of EGF and IGF-1 after massive small bowel resection does not appear to significantly alter the small intestine epithelial ultrastructure when compared with the control group. The increase in lysosomes in some of the enterocytes of the animals exposed to growth factors may be important because this finding was not seen in any of the control electron photomicrographs. Studies to evaluate enterocyte gene and protein expression are necessary to determine the mechanism of EGF and IGF-1 enhancement of substrate absorption beyond intestinal adaptation.

Estrogen and progesterone receptors in salivary gland adenoid cystic carcinoma.

Adenoid cystic carcinomas of salivary glands occur more frequently in women and bear remarkable similarity to adenoid cystic carcinomas of the breast. In addition, breast carcinomas express estrogen and progesterone receptors that impact prognostic significance. This suggests a possible role for sex steroid hormones in the development and progression of salivary gland adenoid cystic carcinoma. On this basis, 12 samples of formalin-fixed, paraffin-embedded salivary gland adenoid cystic carcinomas and 12 samples of normal salivary gland tissue were immunohistochemically evaluated for estrogen and progesterone receptor protein expression. Estrogen receptors were not detected in either group; however, a significantly higher progesterone receptor level was evident in the neoplastic group compared with normal tissue (p < 0.01). These data confirm the presence of progesterone receptors within normal and neoplastic salivary gland tissue. Progesterone receptor expression may be of possible prognostic and therapeutic value in some cases of adenoid cystic carcinoma.

Estrogen receptor detection in paraffin sections of adenocarcinoma of the colon, pancreas, and lung.

We performed a retrospective analysis for the presence of estrogen receptors (ERs) in known cases of adenocarcinoma of the colon, pancreas, and lung. Estrogen receptor status was determined by immunohistochemical methods using the ER-ICA (Abbott Laboratories, North Chicago, Ill) antibody on paraffin sections. None of 43 colon and 18 pancreatic adenocarcinomas demonstrated ERs by this method. Three of 42 lung adenocarcinomas exhibited some degree of nuclear staining for ERs. When evaluating an adenocarcinoma of unknown primary site, the ER-ICA antibody can be useful when included in a panel of antibodies. Positive results tend to exclude colonic or pancreatic, but not pulmonary, primary sites.

Diagnosis of oral hairy leukoplakia by ultrastructural examination of exfoliative cytologic specimens.

Lingual exfoliative cytologic specimens (scrapings) were obtained from 18 patients positive for human immunodeficiency virus with clinical oral hairy leukoplakia. Buccal mucosal scrapings were obtained from 12 of these patients. The specimens were processed for examination by transmission electron microscopy (TEM). Sixteen (89%) of the lingual specimens revealed infection of keratinocytes by herpes-type virus. There was no evidence of virus infection in the 12 buccal mucosal scrapings. Fungal hyphae were seen by TEM in 14 (78%) of the lingual scrapings and two (17%) of the buccal scrapings. One exfoliative specimen and two biopsy specimens were stained for Epstein-Barr virus DNA with a DNA probe. The demonstration of herpes-type virions by TEM in keratinocytes from a lesion clinically suspected to be hairy leukoplakia provides direct, objective diagnosis. Furthermore, use of exfoliative cytologic specimens provides a clinically simple, noninvasive technique.

Cytomegalovirus-infected cells express Leu-M1 antigen. A potential source of diagnostic error.

The authors examined cytomegalovirus (CMV)-infected tissues and Hodgkin's Disease (HD) cases with immunohistochemical assays for Leu-M1 and CMV. The cytologic characteristics were correlated with immunostaining patterns. Cytomegalovirus-infected cells in lymph node, lung, and esophagus sections showed Cowdry type A inclusions, and many had granular cytoplasmic inclusions. All infected cells showed nuclear staining with an anti-CMV antibody. Leu-M1 reacted with CMV-infected cells in cytoplasmic areas, particularly near the nucleus simulating the characteristic staining pattern of Reed-Sternberg (R-S) cells. Cytoplasmic staining intensified as the intranuclear inclusions increased in size. Reed-Sternberg cells showed characteristic Leu-M1 positivity along the cell membrane and golgi zone. At times, Leu-M1 staining of CMV-infected cells was indistinguishable from that of R-S cells. None of the R-S cells reacted with the antibody to CMV. Recognition of the reactivity of Leu-M1 with CMV-infected cells is important in avoiding misdiagnosis of CMV lymphadenitis as HD.

Fine-structural alterations in Leishmania tropica within human macrophages exposed to antileishmanial drugs in vitro.

The mechanism of action of antileishmanial compounds is poorly understood. Ultrastructural changes in Leishmania tropica within human macrophages exposed in vitro to Pentostam, pentamidine, amphotericin B, WR 6026, ketoconazole, and Formycin B were examined in these experiments. In Pentostam-treated cultures, some organisms exhibited diminished definition of mitochondrial and other membranes, while other organisms had completely disintegrated. Pentostam-exposed macrophages demonstrated loss of membrane definition in the absence of further alterations; it is therefore hypothesized that impaired macrophage membrane function may contribute towards the effect of this drug against macrophage-contained organisms. Leishmania parasites in pentamidine-treated cultures initially demonstrated swollen kinetoplasts and fragmentation of the kinetoplast DNA core. The initial observed effect of the other four drugs on the parasites was cytoplasmic condensation. These ultrastructural studies suggest that all five non-antimonial drugs may have different mechanisms of action than antimony (Pentostam) against Leishmania.

The T-axial membrane system in striated muscles of the horseshoe crab.

Cardiac muscle and skeletal muscles powering walking leg, tailspine and gill movements in Limulus polyphemus were studied by transmission electron microscopy. All muscles examined had extensive invaginations of the sarcolemma at the Z disc and at the lateral margins of the A band. Invaginations at the Z disc were often branched in the transverse and longitudinal planes, but branching was not observed at other locations within a sarcomere. Dyads, and occasional triads, were observed at the A band in all muscles examined.