Torsional constant of 27-mer DNA oligomers of different sequences.

We have studied the torsional elastic constant (alpha) of short DNA (27mer) oligomers of various sequence by fluorescence polarization anysotropy (FPA) measurements. The lowest alpha values were found in samples with sequence rich in AA dinucleotides or containing the alternating d(A-T) x d(A-T) motif. The torsional rigidity of our DNA samples was compared to that calculated according to the current values of twist angle fluctuations derived for ten dinucleotide steps by recent analyses of DNA crystal structure database. The values of torsional rigidity derived from crystals are higher than our experimental ones, obtained by FPA analysis, suggesting that packing force in crystals may notably hinder the dinucleotide twist angle fluctuations that occur in solution. This behaviour is more evident for samples containing AA, TA and AT steps. In all the samples there is about a twofold change of the alpha value in the 10-40 degrees C range. An activation enthalpy (Delta H (#)) of about 17.4 kJ mol(-1), on average, was obtained for the temperature dependence of eight of the ten samples studied. A correlation with the stacking energy is discussed.     

Simultaneous analysis of skin response to the different L.E.T. regions of a 55 MeV helium ion beam

Summary Rat tail epidermis was used to analyze the in vivo response of a biological system to heavy particle irradiation. The conical configuration of the rat tail gives rise to a variable energy degradation of the beam thus yielding information on the damage elicited by 2 different L.E.T. regions of the helium beam at different sites on the same sample. Cytochrome oxidase activity and epidermal thickness were used to analyze the metabolic and structural radioinduced response. Quantitative evaluation of radiation damage revealed marked variations within a few micrometers of tissue.     

Release of diamine oxidase into plasma by glycosaminoglycans in rats

Plasma diamine oxidase (DAO) values are enhanced by intravenous injection of heparin which releases the enzyme, synthesized in small bowel enterocytes, from binding sites located on endothelial cells of the intestinal microvasculature. Intestinal DAO, in analogy with lipoprotein lipase (another heparin-released enzyme), is believed to be electrostatically linked to endothelial binding sites composed of a glycosaminoglycan (GAG) which is presumably heparan sulphate, but the complete mechanism of enzyme release is not known. In this study we assayed in rats the DAO-releasing capability of heparan sulphate, dermatan sulphate, chondroitin sulphate A and hyaluronic acid, all heparin related compounds. Heparan sulphate, a compound with the same hexosamine as heparin but with a lower concentration of sulphated iduronic acid, induced a very high release of DAO (3-fold less than heparin), while the other tested GAGs, composed of higher proportions of non sulphated uronic acid and with galactosamine instead of glucosamine, induced a significantly lower release. In rats treated with 60 mg heparan sulphate the significant decrease in ileal mucosal DAO activity indicates that, in analogy with heparin, the high plasma enzymatic activity induced is of enterocytic origin. It is suggested that the high charge density of the compounds tested, due to the degree of sulphatation, is the decisive factor in promoting the release of intestinal DAO.     

Diffusione pollinica e caratteristiche immunologiche e broncoreattive di soggetti atopici in Pietra Ligure (Savona)

Riassunto Sono state rilevate durante un monitoraggio aerobiologico effettuato a Pietra Ligure (Savona) nel corso del 1987 le concentrazioni polliniche di 50 taxa ed è stata valutata l'influenza relativa dei fattori meteorologici. Le osservazioni palinologiche sono state rapportate alle concentrazioni sieriche delle IgE specifiche, alla reattività bronchiale specifica ed aspecifica valutate in 101 pazienti allergici (rinitici ed asmatici), sensibilizzati a Graminaceae ed Urticaceae (Parietaria) al fine di riconoscere correlazioni tra le caratteristiche aerobiologiche di questi allergeni edi meccanismi patogenetici che sostengono la reattività bronchiale.      

Incidence of sensitisation to the pollens of urticaceae (Parietaria), Poaceae and Oleaceae (Olea europea) and pollen rain in Liguria (Italy)

Summary The authors examined 734 sensitised patients living in four localities in Liguria (Genoa, Savona, Pietra Ligure and Sanremo). The commonest source of sensitisation (62.7%) was Urticaceae (Parietaria), followed by Poaceae (52.5%) andOlea europaea L. (24.0%). A survey of airborne pollens revealed a greater presence of Urticaceae and Poaceae in Genoa and of Oleaceae in Pietra Ligure and Sanremo.     

Amino Acid Analysis Demonstrates that Increased Plasma Free Tryptophan Causes the Increase of Brain Tryptophan During Exercise in the Rat

Rats were trained to run on a horizontal treadmill for 2 h at 20 m/min. This activity considerably increased plasma free tryptophan (TRP) (+70%) but did not alter plasma total TRP levels and had little or no effect on plasma concentrations of the other large neutral amino acids (LNAAs) that compete with TRP for entry into the brain. Brain TRP levels increased by 80%. The only other brain LNAA to be affected by exercise was threonine, which rose moderately. The results indicate that increased plasma free TRP was specifically responsible for the increase of brain TRP after 2 h of exercise. Brain lysine was also increased whereas glycine, alanine, and gamma-aminobutyric acid were decreased. The differences between the present findings and those previously obtained following 2 h immobilization stress are discussed.