Evidence for down-regulation of beta-2-adreno-ceptors in cirrhotic patients with severe ascites

The density and affinity of beta-2-adrenoceptors on mononuclear cells from peripheral blood were studied in fifteen patients with cirrhosis of different severity and in thirteen controls. There was no significant difference between cirrhotic patients and controls in density or affinity of beta-2 binding sites. Within the cirrhotic group, however, the number of binding sites per cell was significantly lower in patients with severe ascites than in patients with mild to moderate or no ascites. This down-regulation of beta-adrenoceptors could influence the haemodynamic response to beta-blockers

Down Regulation of Beta Adrenergic Receptors in S49 Lymphoma Cells Induced by Atypical Agonists'

ABSTRAC

Dopamine-B-Hydroxylase activity in rat hypothalamus during the estrus cycle

This experiment provides a direct test of our previous suggestion that estradiol regulates dopamine-B-hydroxylase (DBH) activity in hypothalamic loci. Anterior, medial and posterior hypothalamic slices from triplets of rats were taken during estrus and diestrus and assayed for DBH activity using the technique of Molinoff et al. [15]. DBH activity was measured in hypothalamic slices on three different occasions from the three triplets during the estrous phase of thecycle and also from separate triplets during the diestrous stage of the cycle. Results showed a significant increase in DBH activity during the estrous phase of the cycle. Increased activity did not appear to be anatomically localized within the tissue slices. Explanation of the results has been discussed in terms of possible mechanisms of action.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22032/1/0000450.pd

Unraveling the Genetics of Human Obesity

The use of modern molecular biology tools in deciphering the perturbed biochemistry and physiology underlying the obese state has proven invaluable. Identifying the hypothalamic leptin/melanocortin pathway as critical in many cases of monogenic obesity has permitted targeted, hypothesis-driven experiments to be performed, and has implicated new candidates as causative for previously uncharacterized clinical cases of obesity. Meanwhile, the effects of mutations in the melanocortin-4 receptor gene, for which the obese phenotype varies in the degree of severity among individuals, are now thought to be influenced by one's environmental surroundings. Molecular approaches have revealed that syndromes (Prader-Willi and Bardet-Biedl) previously assumed to be controlled by a single gene are, conversely, regulated by multiple elements. Finally, the application of comprehensive profiling technologies coupled with creative statistical analyses has revealed that interactions between genetic and environmental factors are responsible for the common obesity currently challenging many Westernized societies. As such, an improved understanding of the different “types” of obesity not only permits the development of potential therapies, but also proposes novel and often unexpected directions in deciphering the dysfunctional state of obesity

The effect of Young's modulus on the neuronal differentiation of mouse embryonic stem cells

There is substantial evidence that cells produce a diverse response to changes in ECM stiffness depending on their identity. Our aim was to understand how stiffness impacts neuronal differentiation of embryonic stem cells (ESC's), and how this varies at three specific stages of the differentiation process. In this investigation, three effects of stiffness on cells were considered; attachment, expansion and phenotypic changes during differentiation. Stiffness was varied from 2 kPa to 18 kPa to finally 35 kPa. Attachment was found to decrease with increasing stiffness for both ESC's (with a 95% decrease on 35 kPa compared to 2 kPa) and neural precursors (with a 83% decrease on 35 kPa). The attachment of immature neurons was unaffected by stiffness. Expansion was independent of stiffness for all cell types, implying that the proliferation of cells during this differentiation process was independent of Young's modulus. Stiffness had no effect upon phenotypic changes during differentiation for mESC's and neural precursors. 2 kPa increased the proportion of cells that differentiated from immature into mature neurons. Taken together our findings imply that the impact of Young's modulus on attachment diminishes as neuronal cells become more mature. Conversely, the impact of Young's modulus on changes in phenotype increased as cells became more mature

Characteristics of an adenosine A1 binding site in human placental membranes

Binding sites were solubilized from human placental membrane using 1.5% sodium cholate and were assayed using polyethylene glycol precipitation. These soluble binding sites had properties of an adenosine A1 binding site. 2-[3H]Chloroadenosine and N-[3H]-ethylcarboxamidoadenosine (NECA) binding were time dependent and reversible. Scatchard plots indicate two classes of binding sites with Kd values of 6 and 357 n for 2-chloro[8-3H]adenosine and 0.1 and 26 n with [3H]NECA. The specificity of [3H]NECA binding was assessed by the ability of adenosine analogs to compete for binding sites. Using this approach the estimated IC50 values were 60 n for N6-((R)-1-methyl-2-phenylethyl)adenosine (R-PIA), 160 n for S-PIA, 80 n for NECA, and 20 n for 2-chloroadenosine. Binding of [3H]NECA to the soluble sites is inhibited to 48% of the control value by 100 [mu] guanylyl-5'-imidodiphosphate (Gpp(NH)p). The IC50 value for NECA binding to the soluble binding site was increased from 80 n to 1500 by Gpp(NH)p. There was a shift of binding affinity from a mixture of high and low affinity to only low affinity with 100 [mu] Gpp(NH)p. Despite these alterations a NECA prelabeled molecular species of 150 kDa did not decrease in molecular weight upon the addition of 100 [mu] Gpp(NH)p during high-performance liquid chromatography on a Superose 12 column. Other evidence to support the concept of preferential solubilization and assay of a small population of A1 binding sites was obtained. Following solubilization adenosine A2-like binding sites could be detected only in reconstituted vesicles. The existence of small amounts of A1 binding sites in intact human placental membranes was directly demonstrated using the A1 agonist ligand N6-[3H]cyclohexyladenosine and the A1 antagonist ligand 8-[3H]cyclopentyl-1,3-dipropylxanthine. JAR choriocarcinoma cells have "A2-like" membrane binding sites. In contrast to placental membranes, only A2-like binding sites could be solubilized from JAR choriocarcinoma cells. These observations indicate that human placental membranes contain adenosine A1 binding sites in addition to A2-like binding sites. These sites are guanine nucleotide sensitive, but do not shift to a lower molecular weight form upon assumption of a low affinity state.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28151/1/0000603.pd