Dual compartment (bicameral) culture: role of basement membrane in epithelial differentiation

A number of years ago we reported that tight junctions between adjacent Sertoli cells subdivide the seminiferous epithelium into two compartments, basal and adluminal, thus forming the morphological basis of the blood-testis barrier. It is now generally believed that the special milieu created by the Sertoli cells in the adluminal compartment is essential for germ cell differentiation. In order to duplicate the compartmentalization that occurs in vivo, Sertoli cells were cultured in bicameral chambers on Millipore filters impregnated with a reconstituted basement membrane. Confluent monolayers of these cells were tall columnar (40–60 µ in height) and highly polarized. These Sertoli cell monolayers established electrical resistance that peaked when the Sertoli-Sertoli tight junctions developed in culture. In addition, the monolayers formed a permeability barrier to ³H-inulin and lanthanum nitrate. The bicameral chambers were utilized in a number of studies on protein secretion, and it was revealed that numerous proteens are secreted in a polarized manner. In another study, hormone- stimulated aromatase activity was measured in Sertoli cells grown on plastic culture dishes, plastic dishes coated with laminin or Matrigel, and in the bicameral chambers. Cell culture on basement membrane substrate decreased the FSH-dependent estrogen production. No estrogen production was observed when the Sertoli cells were cultured in the bicameral chambers. These results are in accord with the hypothesis that differentiated Sertoli cells lose their ability to metabolize androgen to estrogen in an hormone-dependent manner, whereas undifferentiated cells in culture, or in vivo, have a very active FSH-dependent aromatase activity. This bicameral culture system could serve as an important model system to examine various functions of Sertoli cells including interactions of Sertoli cells with germ, Leydig, and myoid cells.     

Quinidine: an “Endangered Species” Drug Appropriate for Management of Electrical Storm in Brugada Syndrome

Brugada syndrome is an inherited channelopathy associated with an increased risk of syncope and sudden cardiac death. In rare cases it can be manifested with electrical storm. We report two cases of Brugada syndrome that presented with electrical storm and were treated successfully with oral quinidine, an "endangered species" drug.     

Mapping functional associations in the entire genome of Drosophila melanogaster using fusion analysis

We have previously shown that the detection of gene fusion events can contribute towards the elucidation of functional associations of proteins within entire genomes. Here we have analysed the entire genome of Drosophila melanogaster using fusion analysis and two additional constraints that improve the reliability of the predictions, viz. low sequence similarity and low degree of paralogy of the component proteins involved in a fusion event. Imposing these constraints, the total number of unique component pairs is reduced from 18 654 to a mere 220 cases, which are expected to represent some of the most reliably detected functionally associated proteins. Using additional information from sequence databases, we have been able to detect pairs of functionally associated proteins with important functions in cellular and developmental pathways, such as spermatogenesis and programmed cell death.     

Diterpenes from the brown algae Dictyota dichotoma and Dictyota linearis

Nineteen secondary metabolites of the brown alga Dictyota dichotoma (Huds.) Lam. and fifteen metabolites of the brown alga D. linearis (Ag.) Grev. were isolated and their chemical structures were elucidated on the basis of their NMR and mass spectral data. The diterpenes isopachydictyolal (1) from D. dichotoma and 4alpha-acetyldictyodial (2) from D. linearis are new natural products. The antiviral activity of metabolites isolated in adequate amounts was evaluated in laboratory assays against Herpes simplex virus I (HSV I) and Poliomyelitis Virus I, using Vero cells as hosts.     

Lipids of Pinus halepensis pollen

The total lipids of Pinus halepensis pollen were separated into individual classes of neutral and polar lipids and the components of each class were identified and determined quantitatively. Free fatty acids, waxes and triacylglycerols were found as the main constituents of neutral lipids and phosphatidylcholine and phosphatidylethanolamine of polar lipids. Glycerylether derivatives were detected in neutral and polar lipid fractions. Free and esterified volatile fatty acids were also found in pollen and its neutral lipid fraction.     

Deleterious mutations in LRBA are associated with a syndrome of immune deficiency and autoimmunity

Most autosomal genetic causes of childhood-onset hypogammaglobulinemia are currently not well understood. Most affected individuals are simplex cases, but both autosomal-dominant and autosomal-recessive inheritance have been described. We performed genetic linkage analysis in consanguineous families affected by hypogammaglobulinemia. Four consanguineous families with childhood-onset humoral immune deficiency and features of autoimmunity shared genotype evidence for a linkage interval on chromosome 4q. Sequencing of positional candidate genes revealed that in each family, affected individuals had a distinct homozygous mutation in LRBA (lipopolysaccharide responsive beige-like anchor protein). All LRBA mutations segregated with the disease because homozygous individuals showed hypogammaglobulinemia and autoimmunity, whereas heterozygous individuals were healthy. These mutations were absent in healthy controls. Individuals with homozygous LRBA mutations had no LRBA, had disturbed B cell development, defective in vitro B cell activation, plasmablast formation, and immunoglobulin secretion, and had low proliferative responses. We conclude that mutations in LRBA cause an immune deficiency characterized by defects in B cell activation and autophagy and by susceptibility to apoptosis, all of which are associated with a clinical phenotype of hypogammaglobulinemia and autoimmunity.     

Isolation and characterization of a carcinoma-associated antigen

GA733 is a murine IgG2a monoclonal antibody (MAb) against human gastric carcinoma and is highly tumoricidal in nude mice. The GA733 antigen is a cell surface protein with two subunits of 30,000 and 40,000 daltons. The antigen isolated by immunoaffinity chromatography consists mainly of the 30,000-dalton subunit which bears the GA733 epitope. This subunit displayed several isoelectric points between 6.9 and 7.7. Anti-colon carcinoma MAb 17-1A also detects this antigen, but probably binds to a different epitope.