The response of cyclic 3',5'-AMP and cyclic 3',5'-GMP phosphodiesterases to experimental diabetes

Alloxan diabetes caused a decrease in cyclic AMP phosphodiesterase in all affected rat tissues. Cyclic GMP phosphodiesterase activity was, however, decreased in adipose and liver, but increased increased in heart and uterus.     

Regulation of a protein synthesis initiation factor by adenovirus virus-associated RNA

A small RNA accumulating late in adenovirus infection is required for efficient protein synthesis, although not specifically for the translation of viral proteins. This RNA maintains the activity of an initiation factor catalysing the earliest step of polypeptide chain initiation.     

A point mutation in the neu oncogene mimics ligand induction of receptor aggregation

The rat neu gene, which encodes a protein closely related to the epidermal growth factor receptor, is a proto-oncogene that can be converted into an oncogene by a point mutation. Both genes encode proteins with a relative molecular mass of 185,000 but the question of why the neu gene product, p185neu, is oncogenic, whereas the product of c-neu, p185c-neu, is not, remains unanswered. The proteins have several features common to the family of tyrosine kinase growth-factor receptors, including cysteine-rich external domains, a hydrophobic transmembrane region and a cytoplasmic tyrosine kinase domain. The oncogenic p185neu differs from p185c-neu by an amino-acid substitution in the transmembrane region of the glycoprotein: this replacement of valine by glutamic acid at position 664 induces increased intrinsic tyrosine kinase activity which is associated with transformation. Many glycoproteins with charged amino acids in the transmembrane region exist as multimeric complexes at the plasma membrane. We have therefore investigated the association state of both products of the neu gene and show that the oncoprotein p185neu is organized at the plasma membrane primarily in an aggregated form, but that p185c-neu is not. Induction of an aggregated state may mimic aspects of ligand-induced receptor aggregation resulting in enzymatic activation that leads to cellular transformation.     

Identification of angiogenic activity and the cloning and expression of platelet-derived endothelial cell growth factor

Cloning and sequencing of the complementary DNA for platelet-derived endothelial cell growth factor indicates that it is a novel factor distinct from previously characterized proteins. The factor, a protein with a relative molecular mass of about 45,000, stimulates endothelial cell growth and chemotaxis in vitro and angiogenesis in vivo.     

Muscle fluorometry: A determination of the depth of penetration

Summary Fluorometric recordings of NADH (nicotinamide adenine dinucleotide) were made on rabbit papillary muscles. The specimens were placed between the UV light source and a small window of the detection stage. As the muscle was moved over the window in a transverse direction, simultaneous measurement could be taken of transmitted UV light and fluorescent light for various thicknesses of tissue. It is concluded that a muscle thinckness of 0.65 mm, is optimal before absorption of the incident light decreases the fluorescence signal.