1,25-Dihydroxyvitamin D3 enhances the growth of tumors in athymic mice inoculated with receptor rich osteosarcoma cells

We tested the influence of daily subcutaneous injections of 12.5 and 25 pmol of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on the growth of tumors arising from intracutaneous inoculations of athymic nude mice with rat osteogenic sarcoma cells (ROS) and human melanoma cells. Both doses of 1,25(OH)2D3 increased plasma calcium levels after 3 weeks and produced a striking enhancement in tumor weight when the mice received 1,25(OH)2D3 receptor-rich ROS17/2.8 cells. In contrast, 1,25(OH)2D3 caused no consistent effect on tumor weight in mice given G-361 melanoma cells with low receptor copy number or receptor deficient ROS 24/1 cells. Thus, 1,25(OH)2D3 stimulated tumor growth in a receptor dependent fashion, in vivo, instead of inhibiting it as predicted from the reduction of proliferation of cultured cells in the presence of 1,25(OH)2D3.     

Characterization of photosystem 1 chlorophyll a/b-binding apoprotein accumulation in developing soybean using type-specific antibodies.

The structure and supramolecular assembly of the soybean photosystem 1 (PS 1) chlorophyll a/b-binding antenna (LHC 1) was examined. We identified the subunit composition of LHC 1 in soybean and followed the accumulation of individual subunits during light-induced assembly. We observed four LHC 1 subunits, at 23, 22, 21 and 20.5 kDa, obtained partial sequence information by amino-terminal sequence analysis, and classified the 20.5, 22, and 21 kDa subunits as being encoded by type I, II, and IV chlorophyll a/b binding protein genes, respectively. Antisera against LHC 1 subunits were used to follow the accumulation of individual subunits during the light-initiated transition from etioplast to chloroplast. Several points are noteworthy. First, monospecific antibody against the 22 kDa subunit decorated a 25 kDa peptide in etiolated tissue, which declined during maturation. This decline correlated with the light-induced appearance of mature 22 kDa peptide, suggesting a precursor/product relationship. Second, the same antibody identified a 22 kDa protein in mature corn, but not a larger band in etiolated corn, suggesting that LHC 1 accumulation is regulated differently between species before the onset of chlorophyll biosynthesis. Third, the mature 22 kDa subunit appeared somewhat later than the other LHC 1 peptides during greening, implying that this subunit is less intimately associated with the PS1 core than are the subunits appearing earlier in development.     

Familial true hermaphrodism in three siblings: clinical, cytogenetic, histological and hormonal studies.

Three affected siblings with the hermaphrodism are described. The propositi showed the following characteristics: male phenotype and gender role, hypospadias, bilateral scrotal ovotestes with palpable nodules, and absence of müllerian structures. The X chromatin was positive and the Y chromatin was negative in the 3 affected subjects. Their karyotype in peripheral blood lymphocytes and in gonadal fibroblasts was 46,XX and no Y chromosome fluorescence was observed. Plasma FSH was elevated in the 2 older patients and plasma LH was elevated only in the oldest. Plasma testosterone was low and plasma estradiol high in the 3 siblings; plasma progesterone was elevated in 2, but normal in 1 sibling. Since some of the clinical characteristics of these 3 affected siblings are not the most common features in the majority of sporadic cases of true hermaphrodism, it is suggested that the presence of all of them may be the first clue for the clinical suspicion of the familial type of true hermaphrodism.     

Consortium diversity of a sulfate‐reducing biofilm developed at acidic pH influent conditions in a down‐flow fluidized bed reactor

Sulfate reduction is an appropriate approach for the treatment of effluents with sulfate and dissolved metals. In sulfate‐reducing reactors, acetate may largely contribute to the residual organic matter, because not all sulfate reducers are able to couple the oxidation of acetate to the reduction of sulfate, limiting the treatment efficiency. In this study, we investigated the diversity of a bacterial community in the biofilm of a laboratory scale down‐flow fluidized bed reactor, which was developed under sulfidogenic conditions at an influent pH between 4 and 6. The sequence analysis of the microbial community showed that the 16S rRNA gene sequence of almost 50% of the clones had a high similarity with Anaerolineaceae. At second place, 33% of the 16S rRNA phylotypes were affiliated with the sulfate‐reducing bacteria Desulfobacca acetoxidans and Desulfatirhabdium butyrativorans, suggesting that acetotrophic sulfate reduction was occurring in the system. The remaining bacterial phylotypes were related to fermenting bacteria found at the advanced stage of reactor operation. The results indicate that the acetotrophic sulfate‐reducing bacteria were able to remain within the biofilm, which is a significant result because few natural consortia harbor complete oxidizing sulfate‐reducers, improving the acetate removal via sulfate reduction in the reactor.     

Efficacy of a Vaccine Formula against Tuberculosis in Cattle

“Test-and-slaughter” has been successful in industrialized countries to control and eradicate tuberculosis from cattle; however, this strategy is too expensive for developing nations, where the prevalence is especially high. Vaccination with the Calmette-Guérin (BCG) strain has been shown to protect against the development of lesions in vaccinated animals: mouse, cattle and wildlife species. In this study, the immune response and the pathology of vaccinated (BCG-prime and BCG prime-CFP-boosted) and unvaccinated (controls) calves were evaluated under experimental settings. A 10⁶ CFU dose of the BCG strain was inoculated subcutaneously on the neck to two groups of ten animas each. Thirty days after vaccination, one of the vaccinated groups was boosted with an M. bovis culture filtrate protein (CFP). Three months after vaccination, the three groups of animals were challenged with 5×10⁵ CFU via intranasal by aerosol with a field strain of M. bovis. The immune response was monitored throughout the study. Protection was assessed based on immune response (IFN-g release) prechallenge, presence of visible lesions in lymph nodes and lungs at slaughter, and presence of bacilli in lymph nodes and lung samples in histological analysis. Vaccinated cattle, either with the BCG alone or with BCG and boosted with CFP showed higher IFN-g response, fewer lesions, and fewer bacilli per lesion than unvaccinated controls after challenge. Animals with low levels of IFN-g postvaccine-prechallenge showed more lesions than animals with high levels. Results from this study support the argument that vaccination could be incorporated into control programs to reduce the incidence of TB in cattle in countries with high prevalence.     

Sterol carrier protein-2 expression alters plasma membrane lipid distribution and cholesterol dynamics

Although sterol carrier protein-2 (SCP-2) binds, transfers, and/or enhances the metabolism of many membrane lipid species (fatty acids, cholesterol, phospholipids), it is not known if SCP-2 expression actually alters the membrane distribution of lipids in living cells or tissues. As shown herein for the first time, expression of SCP-2 in transfected L-cell fibroblasts reduced the plasma membrane levels of lipid species known to traffic through the HDL-receptor-mediated efflux pathway: cholesterol, cholesteryl esters, and phospholipids. While the ratio of cholesterol/phospholipid in plasma membranes of intact cells was not changed by SCP-2 expression, phosphatidylinositol, a molecule important to intracellular signaling and vesicular trafficking, and anionic phospholipids were selectively retained. Only modest alterations in plasma membrane phospholipid percent fatty acid composition but no overall change in the proportion of saturated, unsaturated, monounsaturated, or polyunsaturated fatty acids were observed. The reduced plasma membrane content of cholesterol was not due to SCP-2 inhibition of sterol transfer from the lysosomes to the plasma membranes. SCP-2 dramatically enhanced sterol transfer from isolated lysosomal membranes to plasma membranes by eliciting detectable sterol transfer within 30 s, decreasing the t(1/2) for sterol transfer 364-fold from >4 days to 7-15 min, and inducing formation of rapidly transferable sterol domains. In summary, data obtained with intact transfected cells and in vitro sterol transfer assays showed that SCP-2 expression (i) selectively modulated plasma membrane lipid composition and (ii) decreased the plasma membrane content cholesterol, an effect potentially due to more rapid SCP-2-mediated cholesterol transfer from versus to the plasma membrane.     

Pro-sterol carrier protein-2: role of the N-terminal presequence in structure, function, and peroxisomal targeting

Although the 20-amino acid presequence present in 15-kDa pro-sterol carrier protein-2 (pro-SCP-2, the precursor of the mature 13-kDa SCP-2) alters the function of SCP-2 in lipid metabolism, the molecular basis for this effect is unresolved. The presequence dramatically altered SCP-2 structure as determined by circular dichroism, mass spectroscopy, and antibody accessibility such that pro-SCP-2 had 3-fold less alpha-helix, 7-fold more beta-structure, 6-fold more reactive C terminus to carboxypeptidase A, 2-fold less binding of anti-SCP-2, and did not enhance sterol transfer from plasma membranes. These differences were not due to protein stability since (i) the same concentration of guanidine hydrochloride was required for 50% unfolding, and (ii) the ligand binding sites displayed the same high affinity (nanomolar K(d) values) in the order: cholesterol straight chain fatty acid > kinked chain fatty acid. Laser scanning confocal microscopy and double immunofluorescence demonstrated that pro-SCP-2 was more efficiently targeted to peroxisomes. Transfection of l-cells or McAR7777 hepatoma cells with cDNA encoding pro-SCP-2 resulted in 45% and 59% of SCP-2, respectively, colocalizing with the peroxisomal marker PMP70. In contrast, l-cells transfected with cDNA encoding SCP-2 exhibited 3-fold lower colocalization of SCP-2 with PMP70. In summary, the data suggest for the first time that the 20-amino acid presequence of pro-SCP-2 alters SCP-2 structure to facilitate peroxisomal targeting mediated by the C-terminal SKL peroxisomal targeting sequence.