The effect of DL-propranolol on γ-aminolevulinic acid synthetase activity and urinary excretion of porphyrins in allylisopropylacetamide-induced experimental porphyria

Experimental porphyria was induced in rats by allylisopropylacetamide. DL-Propranolol, a β-adrenergic-receptor blocking agent, significantly reduced the elevated urinary excretion of δ-aminolevulinic acid, porphobilinogen and total porphyrins. DL-Propranolol also partially prevented the increased activity of δ-aminolevulinic acid synthesis in liver homogenates of allylisopropylacetamide-treated rats. It had no effect on the above parameters in normal rats. These findings support the hypothesis that δ-aminolevulinic acid exists in two forms, a constitutive and an inducible one.In order to examine whether the action of the drug was caused by its membrane effect. D-propranolol and quinidine sulphate were used in similar sets of experiments. These drugs had no effect on the abnormal porphyrin metabolism of allylisoprpyl-acetamide-treated rats, indicating that the results obtained with DL-propranolol were not due to its membrane action.     

Lipopolysaccharide size and distribution determine serum resistance in Salmonella montevideo.

The survival of Salmonella montevideo during serum treatment depends on the presence of an O antigen (O-Ag) associated with the lipopolysaccharide molecule. In this organism, the O antigen is a polysaccharide composed of 0 to more than 55 subunits, each containing 4 mannose residues together with glucose and n-acetylglucosamine. We used a mutant strain of S. montevideo that requires exogenous mannose for the synthesis of O-Ag. Lipopolysaccharide (LPS) was prepared from these cells grown under three different conditions where the availability of exogenous mannose was regulated such that the average number of O-Ag units per LPS molecule, the percentage of LPS molecules bearing long O-Ag side chains, and the percentage of lipid A cores bearing O-Ag were all varied. These changes in LPS profiles were monitored on sodium dodecyl sulfate-polyacrylamide gels, and cells with different LPS profiles were tested for their ability to survive treatment with pooled normal human serum. Survival in serum was associated with LPS that contained an average of 4 to 5 O-Ag units per LPS molecule, and 20 to 23% of the LPS molecules had more than 14 O-Ag units per LPS molecule. Serum survival was less clearly associated with the percentage of lipid A cores covered with O-Ag. We propose, based on these data and on previous work, that the O-Ag polysaccharide provides the cell protection from serum killing by sterically hindering access of the C5b-9 complex to the outer membrane and that a critical density of long O-Ag polysaccharide is necessary to provide protection.     

Cutaneous blood supply of the penis

Twelve male cadaver specimens were injected with a latex solution to define the cutaneous blood supply of the penis. The cutaneous blood supply of the penile shaft is derived solely from a pair of axial arteries running in the dartos layer. Additional deep perforating arteries from the dorsal penile artery and corporal vessels supply the glans and subcoronal region. An understanding of this anatomy allows one to develop safely a variety of penile skin flaps for difficult reconstructive problems.