Adult-Onset Myopathy with Constitutive Activation of Akt following the Loss of hnRNP-U

Skeletal muscle has the remarkable ability to modulate its mass in response to changes in nutritional input, functional utilization, systemic disease, and age. This is achieved by the coordination of transcriptional and post-transcriptional networks and the signaling cascades balancing anabolic and catabolic processes with energy and nutrient availability. The extent to which alternative splicing regulates these signaling networks is uncertain. Here we investigate the role of the RNA-binding protein hnRNP-U on the expression and splicing of genes and the signaling processes regulating skeletal muscle hypertrophic growth. Muscle-specific Hnrnpu knockout (mKO) mice develop an adult-onset myopathy characterized by the selective atrophy of glycolytic muscle, the constitutive activation of Akt, increases in cellular and metabolic stress gene expression, and changes in the expression and splicing of metabolic and signal transduction genes. These findings link Hnrnpu with the balance between anabolic signaling, cellular and metabolic stress, and physiological growth.

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Hnrnpu mKO mice develop adult-onset myopathy with selective glycolytic muscle atrophy

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Akt is constitutively active in the atrophied muscles of Hnrnpu mKO mice

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Hnrnpu mutants show altered gene expression and alternative splicing patterns

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Induction of genes associated with cellular and metabolic stress

Effects of tricyclic antidepressants on cardiovascular responses to norepinephrine and phenylephrine during pregnancy

The effects of imipramine and amitriptyline on the responses of the uteroplacental vasculature to norepinephrine and phenylephrine were investigated in the pregnant ewe. Experiments were performed on conscious animals in which electromagnetic flow transducers were chronically implanted on the uterine arteries. Administered alone, the tricyclic antidepressants had no effect on mean arterial pressure (MAP) or estimated uteroplacental vascular conductance (UPVCe). Following intravenous infusion of either imipramine (1 mg. per kilogram) or amitriptyline (2.5 mg. per kilogram), the pressor response to norepinephrine (1 microgram per kilogram) and the duration of that response were significantly increased (p less than 0.05). In addition, both the duration of the norepinephrine-produced decrease in uteroplacental blood flow (UPBF) and the amplitude of the decrease in UPVCe were enhanced. In contrast, responses to phenylephrine (2.5 microgram per kilogram) were unaffected by prior administration of either imipramine or amitriptyline. Of additional interest were findings suggesting differential sensitivities to alpha-agonists of the uteroplacental compared with other vascular beds. These observations bring attention to the possibility of interactions between endogenous or exogenous norepinephrine and the tricyclic antidepressants and suggest that the possibly unique sensitivities of the uteroplacental bed should be considered when prescribing drugs during pregnancy.

Oestrone and oestradiol in jugular vein plasma during the oestrous cycle of the cow

The concentrations of oestrone and oestradiol in jugular vein plasma during the bovine oestrous cycle were measured using a fluorescence assay. The highest levels of both oestrogens were found on the 19th and 20th days of a standardized 21-day cycle, with the peak of oestrone occurring slightly before that of oestradiol. Oestrone values ranged from 23·1 to 226·9 ng/100ml and oestradiol varied between 17·6 and 117·5 ng/100 ml. Relatively high values for oestrone concentrations were found on days 6, 7 and 8. These values are comparable to those observed in the ovarian vein blood of the ewe, using both the present method and radioimmunoassay.

The relationship between the oestrogen concentrations reported here and the levels of other hormones during the bovine oestrous cycle is discussed.

Dielectrophoretic separation of living cells

Dielectrophoretic separation studies were undertaken to investigate the possibility of separating cells with varying physiological character. An attempt was made to define the importance of size in the determination of separability. Living cells of Saccharomyces cerevisiae var. ellipsoideus were separated from the same cells killed by heating, using a batch separation. Cells cultured in wort broth were separated from cells grown in yeast nitrogen base – 1% glucose using both batch and continuous separators. Size analyses of separated fractions were performed using a Coulter transducer/multichannel pulse height analyzer. A size differential in cell separability was demonstrated, although it is clear that a complex function of both size and polarizability is instrumental in determining the separation of cell types.