Growth regulatory peptide production by human breast carcinoma cells

The mechanisms by which human breast cancers regulate their own growth have been studied by us in an in vitro model system. We showed that specific growth factors (IGF-I, TGF alpha, PDGF) are secreted by human breast cancer cells. A variety of experiments suggest that they are involved in tumor growth and progression. These activities are induced by estradiol in hormone-dependent breast cancer cells and secreted constitutively by estrogen-independent cells. Concentrates of conditioned medium derived from breast cancer cells can induce the growth of hormone-dependent cells in vivo in athymic nude mice. Hormone-dependent breast cancer cells also secrete TGF beta. TGF beta is growth inhibitory. Growth inhibitors such as antiestrogens or glucocorticoids increase TGF beta secretion. An antiestrogen-resistant mutant of MCF-7 cells does not secrete TGF beta when treated with antiestrogen, but is growth inhibited when treated with exogenous TGF beta. Thus, TGF beta functions as a negative autocrine growth regulator and is probably responsible for some of the growth inhibitory effects of antiestrogens.     

Combination treatment with cholestyramine and bezafibrate for heterozygous familial hypercholesterolaemia.

Cholestyramine and bezafibrate were compared individually and in combination in the treatment of 18 patients with heterozygous familial hypercholesterolaemia. The study used a double blind, placebo controlled block design with a placebo run in period of two months followed by three phases of active treatment, each of two months'' duration. Patients were randomly allocated to one of the six possible sequences of medication so that three patients would be treated with each sequence. Two patients withdrew from the study before completion. The median concentration of total cholesterol decreased from 9.65 mmol/l (interquartile range 8.62 to 8.72) to 7.24 mmol/l (6.70 to 7.52) with cholestyramine, to 8.09 mmol/l (7.18 to 8.68) with bezafibrate, and to 6.31 mmol/l (5.84 to 7.27) with the combination. This fall was due almost entirely to a decrease in the low density lipoprotein cholesterol concentration, and the combination was significantly more effective than either drug alone. The 98% confidence intervals for the median differences between the combination and cholestyramine and the combination and bezafibrate were 0.04 to 1.49 mmol/l and 0.51 to 2.18 mmol/l respectively. These results suggest that this combination is an effective and useful treatment in heterozygous familial hypercholesterolaemia.     

Trichinella spiralis: Proteins and antigens isolated from a large-particle fraction derived from the muscle larva

Proteins and antigens derived from a large-particle fraction of muscle larvae of Trichinella spiralis (i.e., the S₃ fraction) were characterized in terms of their molecular weights, isoelectric points, carbohydrate contents, electrophoretic mobilities, antigenicity, and their ability to induce protection in mice. Gel filtration on Sephacryl S-200 yielded 5 major peaks of material while electrophoresis in polyacrylamide gel with sodium dodecyl sulfate revealed a minimum of 28 proteins ranging in MW from 11,000 to 200,000. Analytical isoelectric focusing on acrylamide gel yielded 37 bands of protein, while the periodic acid-Schiff reaction performed on a similar gel revealed 22 glycoproteins. Most proteins were within a pI range of 4.0–7.0, while all of the glycoproteins had pI ranging from 4.0 to 6.5. Immunoelectrophoresis of the S₃ fraction using hyperimmune rabbit serum demonstrated a minimum of 19 precipitin arcs, while crossed immunoelectrophoresis yielded 16 peaks. These determinations were made on several batches of material isolated in the same fashion and gave the same results. Preparative isoelectric focusing yielded 30 fractions. These fractions were assayed for the presence of antigens, then pooled and tested for their ability to induce protection in mice against an oral challenge infection. Fused rocket immunoelectrophoresis of all 30 fractions revealed the presence of a minimum of 18 antigens with pI ranging from 4.0 to 9.0. The pooled fractions (i.e., 1–9; 10–20; 21–30) all protected mice against oral challenge infection, while fraction 5 (pI = 4.3) protected best.     

Structural basis for hemoglobin capture by Staphylococcus aureus cell-surface protein, IsdH

Pathogens must steal iron from their hosts to establish infection. In mammals, hemoglobin (Hb) represents the largest reservoir of iron, and pathogens express Hb-binding proteins to access this source. Here, we show how one of the commonest and most significant human pathogens, Staphylococcus aureus, captures Hb as the first step of an iron-scavenging pathway. The x-ray crystal structure of Hb bound to a domain from the Isd (iron-regulated surface determinant) protein, IsdH, is the first structure of a Hb capture complex to be determined. Surface mutations in Hb that reduce binding to the Hb-receptor limit the capacity of S. aureus to utilize Hb as an iron source, suggesting that Hb sequence is a factor in host susceptibility to infection. The demonstration that pathogens make highly specific recognition complexes with Hb raises the possibility of developing inhibitors of Hb binding as antibacterial agents.     

Involvement of early embryonic miR‐409‐3p in the establishment of anxiety levels in female mice

Small RNA molecules in early embryos, delivered from sperm to zygotes upon fertilization, are required for normal mouse embryonic development. Even modest changes in the levels of sperm‐derived miRNAs appear to influence early embryos and subsequent development. For example, stress‐associated behaviors develop in mice after injection into normal zygotes sets of sperm miRNAs elevated in stressed male mice. Here, we implicate early embryonic miR‐409‐3p in establishing anxiety levels in adult female, but not male mice. First, we found that exposure of male mice to chronic social instability stress, which leads to elevated anxiety in their female offspring across at least three generations through the paternal lineage, elevates sperm miR‐409‐3p levels not only in exposed males, but also in sperm of their F1 and F2 male offspring. Second, we observed that while injection of a mimic of miR‐409‐3p into zygotes from mating control males was incapable of mimicking this effect in offspring derived from them, injection of a specific inhibitor of this miRNA led to the opposite, anxiolytic effect in female, but not male, and offspring. These findings imply that baseline miR‐409‐3p activity in early female embryos is necessary for the expression of normal anxiety levels when they develop into adult females. In addition, elevated embryo miR‐409‐3p activity, possibly as a consequence of stress‐induced elevation of its expression in sperm, may participate in, but may not be sufficient for, the induction of enhanced anxiety.     

Gut Peptide GLP-1 and Its Analogue,Exendin-4, Decrease Alcohol Intake and Reward

Glucagon-like-peptide-1 (GLP-1) is a gut- and neuro-peptide with an important role in the regulation of food intake and glucose metabolism. Interestingly, GLP-1 receptors (GLP-1R) are expressed in key mesolimbic reward areas (including the ventral tegmental area, VTA), innervated by hindbrain GLP-1 neurons. Recently GLP-1 has emerged as a potential regulator of food reward behavior, an effect driven by the mesolimbic GLP-1Rs. Its role in other reward behaviors remains largely unexplored. Since a considerable overlap has been suggested for circuitry controlling reward behavior derived from food and alcohol we hypothesized that GLP-1 and GLP-1Rs could regulate alcohol intake and alcohol reward. We sought to determine whether GLP-1 or its clinically safe stable analogue, Exendin-4, reduce alcohol intake and reward. To determine the potential role of the endogenous GLP-1 in alcohol intake we evaluated whether GLP-1R antagonist, Exendin 9-39, can increase alcohol intake. Furthermore, we set out to evaluate whether VTA GLP-1R activation is sufficient to reduce alcohol intake. Male Wistar rats injected peripherally with GLP-1 or Exendin-4 reduced their alcohol intake in an intermittent access two bottle free choice drinking model. Importantly, a contribution of endogenously released GLP-1 is highlighted by our observation that blockade of GLP-1 receptors alone resulted in an increased alcohol intake. Furthermore, GLP-1 injection reduced alcohol reward in the alcohol conditioned place preference test in mice. To evaluate the neuroanatomical substrate linking GLP-1 with alcohol intake/reward, we selectively microinjected GLP-1 or Exendin 4 into the VTA. This direct stimulation of the VTA GLP-1 receptors potently reduced alcohol intake. Our findings implicate GLP-1R signaling as a novel modulator of alcohol intake and reward. We show for the first time that VTA GLP-1R stimulation leads to reduced alcohol intake. Considering that GLP-1 analogues are already approved for clinical use, this places the GLP system as an exciting new potential therapeutic target for alcohol use disorders.     

Reducing sphingolipid synthesis orchestrates global changes to extend yeast lifespan

Studies of aging and longevity are revealing how diseases that shorten life can be controlled to improve the quality of life and lifespan itself. Two strategies under intense study to accomplish these goals are rapamycin treatment and calorie restriction. New strategies are being discovered including one that uses low‐dose myriocin treatment. Myriocin inhibits the first enzyme in sphingolipid synthesis in all eukaryotes, and we showed recently that low‐dose myriocin treatment increases yeast lifespan at least in part by down‐regulating the sphingolipid‐controlled Pkh1/2‐Sch9 (ortholog of mammalian S6 kinase) signaling pathway. Here we show that myriocin treatment induces global effects and changes expression of approximately forty percent of the yeast genome with 1252 genes up‐regulated and 1497 down‐regulated (P < 0.05) compared with untreated cells. These changes are due to modulation of evolutionarily conserved signaling pathways including activation of the Snf1/AMPK pathway and down‐regulation of the protein kinase A (PKA) and target of rapamycin complex 1 (TORC1) pathways. Many processes that enhance lifespan are regulated by these pathways in response to myriocin treatment including respiration, carbon metabolism, stress resistance, protein synthesis, and autophagy. These extensive effects of myriocin match those of rapamycin and calorie restriction. Our studies in yeast together with other studies in mammals reveal the potential of myriocin or related compounds to lower the incidence of age‐related diseases in humans and improve health span.