Peter Brian Medawar

Patients with coccidioidomycosis manifest a wide variety of severity of infection. Patients with unifocal and particularly multifocal dissemination manifest a defect in host defense mechanisms. This study focuses on the in vitro response to PHA as an indicator of immunoregulatory mechanisms. Study subjects are divided into four groups: Group I—17, patients with active disseminated coccidioidomycosis and lesions in multiple organs; Group II—15, patients with active disseminated coccidioidomycosis and a single lesion; Group III—16, patients with active coccidioidomycosis confined to the lungs; and Group IV—18, patients in whom coccidioidomycosis is inactive. The response to PHA was heterogeneous, even within groups. When cells were cultured in the presence of indomethacin or R020-5720, Group I cells demonstrated highly significant augmentation of the response to PHA (P < 0.002), whereas cells from Groups II to IV were unaffected. When adherent cells were removed by passage through a nylon wool column, the effect of indomethacin could no longer be demonstrated. Direct measurement of prostaglandin production (PGE₂ and PGF_2α) and thromboxane suggest that there is no difference in the quantity of these compounds produced by unstimulated or PHA-stimulated cells by Group I versus Group IV cells (P = 0.2-0.4). Indomethacin or R020-5720 markedly inhibit the production of these compounds. Studies of the effect of exogenous prostaglandin on PHA-stimulated cells suggest that Group I cells may be more inhibited by PGF_1α and PGF_2α compared to Group IV cells. The data demonstrate that PHA cultures of cells from Group I patients are suppressed. The suppressor cell can be removed by adherence to nylon wool and is inhibited by indomethacin or R020-5720.     

Emergence and Phylodynamics of Citrus tristeza virus in Sicily,Italy

Citrus tristeza virus (CTV) outbreaks were detected in Sicily island, Italy for the first time in 2002. To gain insight into the evolutionary forces driving the emergence and phylogeography of these CTV populations, we determined and analyzed the nucleotide sequences of the p20 gene from 108 CTV isolates collected from 2002 to 2009. Bayesian phylogenetic analysis revealed that mild and severe CTV isolates belonging to five different clades (lineages) were introduced in Sicily in 2002. Phylogeographic analysis showed that four lineages co-circulated in the main citrus growing area located in Eastern Sicily. However, only one lineage (composed of mild isolates) spread to distant areas of Sicily and was detected after 2007. No correlation was found between genetic variation and citrus host, indicating that citrus cultivars did not exert differential selective pressures on the virus. The genetic variation of CTV was not structured according to geographical location or sampling time, likely due to the multiple introduction events and a complex migration pattern with intense co- and re-circulation of different lineages in the same area. The phylogenetic structure, statistical tests of neutrality and comparison of synonymous and nonsynonymous substitution rates suggest that weak negative selection and genetic drift following a rapid expansion may be the main causes of the CTV variability observed today in Sicily. Nonetheless, three adjacent amino acids at the p20 N-terminal region were found to be under positive selection, likely resulting from adaptation events.     

Biotransformation of 5α-androstane-3,17-dione by microalgal cultures.

Twenty-four different strains of unicellular algae have been used in the bioconversion of 5α-androstane-3,17-dione.5_α-androstane-3,17-dione has been bioconverted by twenty-four microalgae The activity of algae seems to be species-specific. Reducted, hydroxylated or more unsaturated steroids have been isolated from the cultures.     

Le Stipule e la Fillotassi di “Tropaeolum Majus” L

Riassunto

Le stipule della plantula di Tropacolum majus L. sono emergenze occasionali, che nella pianta adulta sono sostituite nella loro funzione dalla lamina dei nomofilli. La sua fillotassi sparsifolia è derivata dalla oppositifolia per crescenza asimmetrica spiralata della periferia dell'asse.     

Respiration during isometric contraction of the flexor or extensor muscles of the arm in humans

An increase in the instantaneous pulmonary flow and a decrease in the respiratory frequency has been found in man as a consequence of isometric contraction of either flexor or extensor muscles of the elbow. The delay of 200 to 900msec between the onset of the muscle contraction and the beginning of the flow increment suggests that the respiratory system increases its activity due to the proprioreceptor activation. As there is no significant difference in the results obtained during flexor or extensor contraction, the contribution of the two different receptor groups appears to be the same.     

Daily Modifications of 3h-Naloxone Binding Sites in the Rat Brain: A Quantitative Autoradiographic Study

The endogenous opioid peptides, the opiate receptors and several related behaviours, like opioid-mediated analgesia, show daily variations in different animal species including rats. The attempt to correlate the daily rhythm of opiate receptors in the central nervous system (CNS) to opiate related rhythmic phenomena requires an experimental approach with a high anatomical resolution, as the opioid distribution is very heterogeneous. In this paper we present the study of daily variations of 3H-naloxone binding sites in the different regions of the adult male rat brain, performed by means of quantitative autoradiography. Five rats are sacrificed at each investigated time of the day (0200, 0600,1000,1400,1800 and 2200). The ligand is 3H-naloxone(4nM), the quantification is performed by means of densitometric procedures (image analyzer Tesak VDC 501, computer Digital PDP11,3H-microscale). The statistical analysis is performed according to the single Cosinor method and the one-way analysis of variance followed by the multiple range test of Duncan. We analysed 33 different regions of the rat CNS, and the daily variations of opiate receptors are regionally selective. A circadian rhythm is found in the anterior cingulate cortex, hippocampal cortex, periventricular, medial, ventral, reticular and posterior nuclei of the thalamus, rhomboid, gelatinosus and rheuniens nuclei, lateral hypothalamus, locus coeruleus, grey substance of the pons, reticular formation of medulla oblongata, inferior olivary complex, medial part of the nucleus of the solitary tract and nucleus of the spinal tract of the trigeminal nerve. An ultradian rhythm is found in the medial and lateral preoptic areas, in the medial hypothalamus, in the medial and in the lateral nuclei of habenula. No significant variations during 24 hr according to the Cosinor analysis are found in the dorsal and lateral cerebral cortex, striatum, globus pallidus, bed nucleus of the stria terminalis, septal nuclei, lateral nucleus of the thalamus, cochlear nuclei, nucleus of the solitary tract, lateral and caudal parts, dorsal motor nucleus of the vagal nerve, XII and IX nerve nuclei. The amplitude of the daily variations observed ranges from 10 to 40%. Our results demonstrate the high anatomical selectivity of the daily modifications of 3H-naloxone binding sites in the rat CNS. They also indicate that quantitative autoradiography is a suitable and sensitive technique for these studies.