Reversal of basic fibroblast growth factor-mediated autocrine cell transformation by aromatic anionic compounds.

NIH-3T3 cells transfected with basic fibroblast growth factor (bFGF) fused to a signal peptide sequence (spbFGF cells) are transformed in vitro and tumorigenic in vivo. Treatment of spbFGF cells with low and nontoxic concentrations (0.5-2.5 micrograms/ml) of negatively charged, nonsulfated aromatic compounds (e.g., aurin tricarboxylic acid, 4-hydroxyphenoxyacetic acid) resulted in restoration of their normal proliferative rate, morphological appearance, and adhesion properties. Binding and cross-linking experiments using 125I-labeled bFGF revealed that these alterations were associated with an up-regulation of high affinity receptors bFGF receptors was induced by these compounds in spbFGF cells that were seeded on fibronectin to enforce a firm cell attachment and flattening. Thus, induction of spbFGF cell adhesion and spreading may not be related to restoration of normal bFGF-receptor interactions. Although the negatively charged aromatic compounds mimic many of the effects of heparin in other systems (e.g., release of heparin- and heparan sulfate-bound proteins, inhibition of heparanase), heparin, heparan sulfate, and dextran sulfate were not effective at the low concentrations of the anionic compounds used in the present study. Likewise, suramin, a sulfated aromatic molecule, was effective at toxic concentrations, 400-600-fold higher than the nonsulfated aromatic compounds. The development of defined, nontoxic anionic compounds may provide a new strategy to interfere with the autonomous and anchorage independent mode of cell growth involved in autocrine cell transformation and cancer.     

Switching yeast from meiosis to mitosis: double-strand break repair, recombination and synaptonemal complex

Background:

When Saccharomyces cerevisiae cells that have begun meiosis are transferred to mitotic growth conditions (‘return-to-growth’, RTG), they can complete recombination at high meiotic frequencies, but undergo mitotic cell division and remain diploid. It was not known how meiotic recombination intermediates are repaired following RTG. Using molecular and cytological methods, we investigated whether the usual meiotic apparatus could repair meiotically induced DSBs during RTG, or whether other mechanisms are invoked when the developmental context changes.

Results:

Upon RTG, the rapid disappearance of meiotic features—double-strand breaks in DNA (DSBs), synaptonemal complex (SC), and SC related structures—was striking. In wild-type diploids, the repair of meiotic DSBs during RTG was quick and efficient, resulting in homologous recombination. Kinetic analysis of double-strand breakage and recombination indicated that meiotic DSB formation precedes the commitment to meiotic levels of recombination. DSBs were repaired in RTG in dmc1, but not rad51 mutants, hence repair did not occur by the usual meiotic mechanism which requires the Dmc1 gene product. In haploids, DSBs were also repaired quickly and efficiently upon RTG, showing that DSB repair did not require the presence of a homologous chromosome. In all strains examined, SC and related structures were not required for DSB repair or recombination following RTG.

Conclusions:

At least two pathways of DSB repair, which differ from the primary meiotic pathway(s), can occur during RTG: One involving interhomologue recombination, and another involving sister-chromatid exchange. DSB formation precedes commitment to recombination. SC elements appear to prevent sister chromatid exchange in meiosis.

     

The antiatherogenic effect of allicin: possible mode of action.

OBJECTIVE: Garlic (Allium sativum) has been suggested to affect several cardiovascular risk factors. Its antiatherosclerotic properties are mainly attributed to allicin that is produced upon crushing of the garlic clove. Most previous studies used various garlic preparations in which allicin levels were not well defined. In the present study, we evaluated the effects of pure allicin on atherogenesis in experimental mouse models. METHODS AND RESULTS: Daily dietary supplement of allicin, 9 mg/kg body weight, reduced the atherosclerotic plaque area by 68.9 and 56.8% in apolipoprotein E-deficient and low-density lipoprotein (LDL) receptor knockout mice, respectively, as compared with control mice. LDL isolated from allicin-treated groups was more resistant to CuSO(4)-induced oxidation ex vivo than LDL isolated from control mice. Incubation of mouse plasma with (3)H-labeled allicin showed binding of allicin to lipoproteins. By using electron spin resonance, we demonstrated reduced Cu(2+) binding to LDL following allicin treatment. LDL treatment with allicin significantly inhibited both native LDL and oxidized LDL degradation by isolated mouse macrophages. CONCLUSIONS: By using a pure allicin preparation, we were able to show that allicin may affect atherosclerosis not only by acting as an antioxidant, but also by other mechanisms, such as lipoprotein modification and inhibition of LDL uptake and degradation by macrophages.     

Antigen-induced proliferation of murine T-lymphocytes in vitro. II. The effect of different macrophage populations on the antigen-induced proliferative response

Various macrophage-containing preparations were tested for their ability to increase the antigen-specific proliferative response of murine T-lymphocytes. The preparations examined included: peritoneal exudate cells (PEC) from mice injected with mineral oil or thioglycolate; fresh bone-marrow cells; bone-marrow cells grown in culture for up to 11 days; normal spleen cells, and spleen cells from mice injected with mineral oil. The best proliferative response was obtained when the lymphocytes were supplemented with 30% spleen cells from mice injected with mineral oil.When spleen cells from mineral oil injected mice are compared with those of spleen cells from normal mice, it is evident that mineral oil given i.p. activates the spleen macrophages. Although the number and percentage of macrophages in the spleen does not increase following mineral oil injection, the activities of some of their enzymes (acid phosphatase and β-glucuronidase) increase while others do not change (Cathepsin D and lysozyme). Furthermore, the Fc-dependent phagocytic activity of spleen macrophages and their spreading on plastic culture dishes is increased after mineral oil treatment.We conclude that the activation of spleen macrophages caused by an i.p. injection of mineral oil also induced changes in their antigen-presenting apparatus. Consequently, macrophages from spleens of mineral oil-injected mice are most suitable cell preparations for antigen presentation to T-lymphocytes.     

Nutrient Intake following Vertical Banded Gastroplasty or Gastric Bypass

Background: This study explored eating habits, nutrient intake, and blood vitamin and mineral levels to determine whether severely obese subjects (BMI 40-50 kg m⁻²) post-vertical banded gastroplasty (VBG) or gastric bypass Roux-en-Y (GBR) are at risk of developing compounded under-nutrition. Methods: A dietary follow-up of 36 VBG and 19 GBR was maintained for 18 months via 7-day food intake diaries and 24-h recalls. Food intake was analysed for energy and nutrient composition and for its relative amount to recommended dietary allowances (RDA). Results: Weight loss was greatest during the first 6 months, continued at a slower rate for the next 6 months, nearly ceasing thereafter. The results following GBR were not substantially different from those following VBG 18 months postoperatively. The median weight loss at 1 year postoperatively was 48, 46, 48 and 36 kg; expressed as residual excess body weight: 0.2, 16, 13 and 22% for GBR Men, Women, VBG Men, Women, respectively. According to the classification proposed by Reinhold, all subjects achieved excellent treatment outcomes 18 months postoperatively. Despite the relatively low reported energy intake (20-50% below RDA), no correlation was found between rate of weight loss and energy intake at 6 months postoperatively. The intake of most vitamins and minerals was below 50% of RDA during the 18 months follow-up. The increase in energy intake did not improve the level of the nonenergy-contributing nutrients. Compliance to multivitamin and mineral supplement intake deteriorated with time. Conclusion: The low to within-normal range of blood vitamin and mineral levels 12 months postoperatively suggests the slow development of subclinical nutritional deficiency which could jeopardize the subjects' long-term health status.     

The elephant in the room: talking race in medical education

The deaths of black men and women while in police custody, rising anti-immigrant sentiment and rhetoric in high-income countries, and the continued health disparities experienced by Indigenous communities globally have brought race and racism to the forefront of public discourse in recent years. In a context where academic health science centres are increasingly called to be “socially accountable,” ignoring the larger social context of race and racism is something that medical education institutions can little afford to do. However, many such institutions have largely remained silent on the issue of race and racism, both within and outside of healthcare. Most medical education continues to emphasize a primarily biological understanding of race. We argue that a different approach is needed. Highlighting the social construction of race is an essential starting point for educators and trainees to tackle racialized health disparities in our clinics and to challenge racism in our classrooms, educational and research institutions, and communities.