Isoelectric focusing studies of human pancreatic secretion

Pure bile, pancreatic and duodenal human juices have been analyzed by isoelectric focusing, either at rest or upon stimulation with caerulein. In rats, stimulation has also been performed with secretin. Twenty bands have been resolved and quantified in the pancreatic secretion. By developing zymograms, a number of isozymes have been identified: 6 isoamylases [pI's 7.2, 7.1 and 6.6 (major) and pI's 7.4, 6.7 and 5.8 (minor)], 3 lipases [pI's 7.0 and 6.8 (major) and 6.4 (minor)], two major alkaline proteases (pI's 9.8 and 8.4) and one major acidic protease (pI 4.3) and one band of RNAase activity (pI 8.6). The stimulation kinetics follow a mechanism according to Palade, indicating uniform response to secretogogues, parallel intracellular transport and parallel discharge of pancreatic exocrine proteins.     

Characterization of a basic transthyretin variant - TTR Arg 102 - in the German population

A basic transthyretin (TTR) variant, apparently non-pathogenic, has been reported in a German family. Protein analysis of this TTR variant revealed the substitution of arginine for proline at position 102 of the TTR polypeptide chain. This result was confirmed by DNA analysis of PCR amplified DNA.     

Degradation and mineralization of 3-chlorobiphenyl by a mixed aerobic bacterial culture

Summary A mixed bacterial culture obtained from polychlorinated-biphenyl-contaminated river sediments proved capable of degrading 3-chlorobiphenyl (3-CB) under aerobic laboratory conditions. Almost total mineralization of 150 mg/l of 3-CB occurred when, after 3 days of incubation, the mineral medium was supplied with benzoic acid as a carbon source. Two strains of Pseudomonas capable of degrading the substrate to 3-chlorobenzoic acid and a strain of Pseudomonas fluorescens capable of co-metabolizing this metabolite were selected from the mixed culture. A nearly stoichiometric amount of chloride, which defines the percentage of total mineralization, was eliminated during mixed culture growth. Offprint requests to: F. Fava     

Can sister chromatid intercrossings be considered as prelesions?

Summary In a study of the expression of folate-sensitive fragile sites in five normal individuals using RPMI medium containing methotrexate (MTX), we observed a high frequency of sister chromatid intercrossings (SCI) that is, the intersection of sister chromatids. The location of SCIs corresponded to fragile sites in 54.2% of the cases. Of the SCIs observed in each individual, 43%–53% were located at the same bands as their expressed fragile sites. Furthermore when RPMI+MTX medium was used instead of F-10 medium, the incidence of SCIs increased tenfold. We suggest that SCIs could indicate the existence of a pre-lesion.     

Decorin Protein Core Affects the Global Gene Expression Profile of the Tumor Microenvironment in a Triple-Negative Orthotopic Breast Carcinoma Xenograft Model

Decorin, a member of the small leucine-rich proteoglycan gene family, exists and functions wholly within the tumor microenvironment to suppress tumorigenesis by directly targeting and antagonizing multiple receptor tyrosine kinases, such as the EGFR and Met. This leads to potent and sustained signal attenuation, growth arrest, and angiostasis. We thus sought to evaluate the tumoricidal benefits of systemic decorin on a triple-negative orthotopic breast carcinoma xenograft model. To this end, we employed a novel high-density mixed expression array capable of differentiating and simultaneously measuring gene signatures of both Mus musculus (stromal) and Homo sapiens (epithelial) tissue origins. We found that decorin protein core modulated the differential expression of 374 genes within the stromal compartment of the tumor xenograft. Further, our top gene ontology classes strongly suggests an unexpected and preferential role for decorin protein core to inhibit genes necessary for immunomodulatory responses while simultaneously inducing expression of those possessing cellular adhesion and tumor suppressive gene properties. Rigorous verification of the top scoring candidates led to the discovery of three genes heretofore unlinked to malignant breast cancer that were reproducibly found to be induced in several models of tumor stroma. Collectively, our data provide highly novel and unexpected stromal gene signatures as a direct function of systemic administration of decorin protein core and reveals a fundamental basis of action for decorin to modulate the tumor stroma as a biological mechanism for the ascribed anti-tumorigenic properties.     

Short-term vitamin A supplementation at therapeutic doses induces a pro-oxidative state in the hepatic environment and facilitates calcium-ion-induced oxidative stress in rat liver mitochondria independently from permeability transition pore formation

There is a growing body of evidence showing that vitamin A induces toxic effects in several experimental models and in human beings. In the present work, we have investigated the effects of short-term vitamin A supplementation on the adult rat liver redox status. We have found that vitamin A at therapeutic doses induces a hepatic oxidative insult. Furthermore, we have observed increased antioxidant enzyme activity in the liver of vitamin-A-treated rats. Additionally, some mitochondrial dysfunction was found since superoxide anion production was increased in vitamin-A-treated rat liver submitochondrial particles, which may be the result of impaired mitochondrial electron transfer chain activity, as assessed here. We have also isolated rat liver mitochondria and challenged it with 75 μM CaCl₂, a non-oxidant agent that is able to induce mitochondrial oxidative stress indirectly. We have found that mitochondria isolated from vitamin-A-treated rat liver are more sensitive to CaCl₂ than control mitochondria regarding the redox status. Importantly, vitamin A seems to alter mitochondrial redox status independently of the participation of the mitochondrial permeability transition pore, which is activated by Ca²⁺ ions since cyclosporin A did not prevent the oxidative insult elicited by Ca²⁺ addition. Overall, we show here that mitochondria are a target of vitamin-A-associated toxicity also in vivo.     

Experimental evidence of an increased leaf production in Prosopis after removal of epiphytes (Tillandsia)

The production of new leaves of host trees can be affected by the presence of epiphytic species. This experimental study was planned to evaluate the effects on the mean number of new leaves produced by Prosopis alba considering the factors site-disturbance, different epiphytes loads, and the respective zones in the tree crown. The number of new leaves produced was counted manipulating branches with originally low and high loads of epiphytes at different crown zones, in 10 trees per site. The effect of manual removal of epiphytes on the leaf production of the hosts was analyzed by comparing branch responses in short and medium periods of time (i.e., 6 months and 3 years, respectively). There were no significant differences when comparing the number of new leaves produced in the sampled trees at sites with different human disturbance intensities. By contrast, significant differences were observed between both epiphytic loads treatments and when comparing tree crown zones. Experimental results showed a higher subsequent host leaf production (>100%) in branches where epiphytes were experimentally removed, in comparison with branches with high load of epiphytes The number of new leaves produced in branches with naturally low loads of the epiphytes was higher than 1000% compared to branches with high Tillandsia loads. Finally, a higher significant production of new leaves was observed in the bottom crown zone as compared with the middle and upper crown zones. Furthermore, this trend was confirmed considering a longer time-period (3 years) after experimental removal of epiphytes. A significant increase (>100%) was observed when comparing the production of new leaves between different periods after total epiphyte removal. In consequence, Tillandsia species could be considered as “structural parasites” of Prosopis alba.     

A combined proteome and ultrastructural localization analysis of 14-3-3 proteins in transformed human amnion (AMA) cells: definition of a framework to study isoform-specific differences

The 14-3-3 proteins constitute a family of highly conserved and broadly expressed multifunctional polypeptides that are involved in a variety of important cellular processes that include cell cycle progression, growth, differentiation, and apoptosis. Although the exact cellular function(s) of 14-3-3 proteins is not fully elucidated, as a rule these proteins act by binding to protein ligands, thus regulating their activity; so far more than 300 cellular proteins have been reported to interact with 14-3-3 proteins. Binding to cognate interacting partners is isoform-specific, but redundancy also exists as several binding peptides can be recognized by all isoforms, and some functions can be carried out by any isoform indistinctly. Moreover by interacting with different ligands in a spatially and temporally regulated fashion the same isoform can play multiple possibly even opposing roles where the resultant cellular outcome will be determined by the integration of the various effects. Although there is a large body of literature on specific aspects of 14-3-3 biology, not much is known on the coordinated aspects of 14-3-3 isoform expression, post-translational modifications, and subcellular localization. To address the question of isoform-specific differences, we carried out a comparative analysis of the patterns of expression, phosphorylation, and subcellular localization of the 14-3-3 beta, epsilon, sigma, tau, and zeta protein isoforms in transformed human amnion (AMA) cells. To validate as well as broaden our observations we analyzed the occurrence of the various isoforms in a large number of established cell lines and mammary and urothelial tissue specimens. Given the systematic approach we undertook and our application of isoform-discriminating technologies to the analysis of various cellular systems, we expect the data presented in this study to serve as an enabling resource for researchers working with 14-3-3 proteins.