Showing papers by "University of Florence published in 1982"

Philosophy of quantum mechanics

Abstract: In the recent literature the use of the term “Philosophy of Quantum Mechanics” is very similar to that of the corresponding term “Philosophy of Mathematics”. Its denotation includes a vast class of research: from very technical investigations about the logical foundations of the theory up to general discussions of some traditional gnoseological and metaphysical questions (such as “idealismus” versus “realismus”, etc.).

Lesions of cholinergic forebrain nuclei: changes in avoidance behavior and scopolamine actions.

Abstract: The acquisition of active (shuttle-box) and passive avoidance conditioned responses and the effects of scopolamine on acetylcholine (ACh) output in freely moving rats and on conditioned responses were investigated 20 days after placing a unilateral lesion in the magnocellular forebrain nuclei (MFN) In the lesioned rats spontaneous ACh output from the cerebral cortex ipsilateral to the lesion was slightly decreased, while on the other hand the increase in ACh output elicited by scopolamine was strongly reduced Sham operated rats always performed more active avoidance responses than MFN lesioned rats in the daily training shuttle-box sessions, and the facilitating effect of scopolamine (1 mg/kg IP) on the shuttle-box performance was suppressed However the lesion did not disrupt the shuttle-box performance whenever training had taken place before the lesion In the lesioned rats retested 30 min after the training trial, an impairment of the passive avoidance response was found The effect of the lesion was potentiated by scopolamine The results show therefore that MFN lesions impair the cortical cholinergic mechanisms, whose activity seems to play an important role in cognitive functions

Paleogene magnetic stratigraphy in Umbrian pelagic carbonate rocks: The Contessa sections, Gubbio

Abstract: The Umbrian sequence of pelagic carbonate rocks provides an opportunity for precise correlation between Paleogene biostratigraphy and geomagnetic polarity history. The red-to-pink, Paleocene to middle Eocene Scaglia Rossa limestone, the varicolored upper Eocene Scaglia Variegata limestone, and the gray-green Oligocene Scaglia Cinerea marlstone form a 250-m-thick, continuous exposure in the Contessa Valley near Gubbio, Italy. Magnetostratigraphic, lithostratigraphic, and biostratigraphic investigations in three sections covering the entire Paleogene have confirmed and dated the geomagnetic reversal sequence for most of this period. The ferromagnetic mineral in the Scaglia Cinerea is magnetite and AF demagnetization to peak fields of 20 mT is sufficient to define the characteristic remanent magnetization. The Scaglia Variegata and pink Scaglia Rossa samples contain an additional hematite component which is very pronounced in dark red Paleocene Scaglia Rossa samples. Changes of magnetic mineralogy take place in these limestones during heating, especially above 500 °C. However, thermal demagnetization is effective in isolating the characteristic remanence vectors, which form almost antipodal clusters of directions representing normal and reversed polarities. The directions are rotated counterclockwise, partly due to post-Oligocene tectonism. Paleontological zonations of planktic foraminifera and calcareous nannofossils were hampered by poor preservation, but the major epoch and stage 29, as in the Gubbio Bottaccione section; Paleocene-Eocene, just above anomaly 25; Eocene-Oligocene, between anomalies 13 and 15; Oligocene-Miocene, just below anomaly 6C. These correlations require slight modifications to previous conclusions on Paleogene sea-floor spreading rates.

Latent dysautonomic pupillary lateralization in cluster headache. A pupillometric study.

Abstract: Forty-five patients with cluster headache in the asymptomatic phase were studied by electronic pupillography, testing autonomic function of both pupils pharmacologically. Topical sympathetically-acting mydriatics, tyramine and cocaine and the cholinoceptor blocker, homatropine, induced defective mydriatic responses on the symptomatic side, indicating latent impairment of sympathetic function. The abnormality was found in interattack intervals of the cluster period or during intercluster phases. The tyramine test can be proposed for objective diagnosis of cluster headache. We postulate that cluster attacks are triggered and lateralized by a permanent latent unilateral sympathetic dysfunction. Lithium reduced the mydriatic response to tyramine of the pupil contralateral to the pain, thus restoring the equilibrium between both pupils; this therapy may correct the asymmetric sympathetic function by attenuating the activity in the asymptomatic side.

A reverse Hölder inequality for the eigenfunctions of linear second order elliptic operators

Abstract: An integral inequality for the eigenfunctions of linear second order elliptic operators in divergence form is proved. The result is a generalization of the Payner-Rayner inequality.

THE RECENT (MIOCENE‐QUATERNARY) REGMATIC SYSTEM OF THE WESTERN MEDITERRANEAN REGION: A New Model of Ensialic Geodynamic Evolution, in a Context of Plastic/Rigid Deformation

Abstract: By comparing the features observed on Landsat images with the known geological data, a regmatic system that controlled the entire Neogene to Recent structural evolution of the Western Mediterranean area has been recognized.

Reduced prostacyclin production in patients with different manifestations of ischemic heart disease

Abstract: Prostacyclin, a substance produced by vessel wall, has a sustained vasodilating and platelet antiaggregating activity and therefore the variations in its production in patients with ischemic heart disease are of interest. Prostacyclin production was assessed in 59 patients with ischemic heart disease and 59 control subjects matched for age, sex, body weight, smoking habits, blood pressure and serum cholesterol levels. Of the 59 patients examined, 23 had had a myocardial infarction 3 to 12 months earlier; 21 had had spontaneous angina and 15 effort angina for at least 3 months. Patients with myocardial infarction and spontaneous angina were also classified in subgroups with and without acute coronary insufficiency, according to the occurrence of ischemic attacks in the week preceding the study. Both circulating prostacyclin levels and prostacyclin produced after 3 minutes of ischemia were measured by bioassay. Circulating prostacyclin was significantly less in patients with ischemic heart disease than in matched control subjects independent of the clinical type of ischemic heart disease. Circulating prostacyclin was particularly reduced in patients with acute coronary insufficiency in comparison to patients without, both in the group with myocardial infarction (1.11 ± 0.22 ng/ml and 2.09 ± 1.32, respectively) and in the group with spontaneous angina (1.24 ± 0.42 and 2.17 ± 1.16, respectively). No differences could be found for prostacyclin produced after 3 minutes of ischemia in relation to the presence of acute coronary insufficiency. The lower level of prostacyclin production in patients with ischemic heart disease and especially in those with acute coronary insufficiency may be an important factor in the occurrence of coronary occlusion or spasm.

Atrial refractoriness and spontaneous or induced atrial fibrillation.

Abstract: Atrial refractoriness and vulnerability were studied in 10 patients with paroxysmal atrial fibrillation (PAF) and in 12 age-matched normal subjects (N). Effective and functional refractory periods were measured at three sites of the right atrium: high, middle and low in the lateral wall, both in sinus rhythm and during atrial pacing (120/min). Twice threshold stimuli were applied. Dispersion of refractoriness (D) was measured as the longest minus the shortest refractory period. Atrial fibrillation (AF) was induced in 5 of the PAF; in each of these 5 only one atrial site proved vulnerable (middle in one case, low in the other 4). In every case the shortest refractory period was located at the vulnerable atrial site. In vulnerable patients coupling intervals only slightly different from those which induced AF determined an abrupt change in the atrial electrogram recorded at the vulnerable site, suggesting a modified and in some way abnormal behaviour of the atrial activation wave. At the same time the interval between the beginning of the electrogram at the vulnerable site and of that obtained by the electrode positioned near the A-V node lengthened, suggesting a lower conduction velocity of the atrial activation wave. PAF evidenced significantly higher refractoriness and D than did N during sinus rhythm. Atrial pacing significantly reduced refractoriness but not D, which remained significantly higher than that of N at the same driven frequency. In conclusion, lower cycle length (paced rhythm), a short refractory period and the possibility of delivering extrastimulus at shorter coupling intervals seem conditions favourable to the induction of irregular activation of atrial myocardium. The increased D might be connected to the particular pathophysiological condition of our patients.

Peptide-containing innervation of the human intestinal mucosa. An immunocytochemical study on whole-mount preparations.

Abstract: The three-dimensional distribution of the peptide-containing innervation in the human intestinal mucosa was studied by fluorescence immunohistochemistry on whole-mount mucosal preparations. An extensive VIP-immunoreactive nerve supply was demonstrated at all levels, but was markedly increased in density in the distal intestine, where it formed a particularly rich network in close contact with the luminal epithelium. In contrast, substance P-containing nerve fibres formed a looser and evenly distributed innervation at all levels. The muscularis mucosae was richly supplied by VIP- and substance P-containing fibres. Met-enkephalin immunoreactivity was confined to a few scattered nerve bundles running in the muscularis mucosae and around the bottom of epithelial crypts.

Acid and basic late neogene volcanism in central aegean sea: Its nature and geotectonic significance

Abstract: Local eruptions of acid volcanic rocks occurred in the Central Aegean region around the Miocene-Pliocene boundary. Rhyolites outcrop on the Island of Antiparos, located in the central part of the Attic-Cycladic Massif. The age of these volcanic rocks ranges from 4.0 to 5.4 m.y., and chemical and Sr isotopic data suggest they were generated by partial melting of the continental crust. At the same time, along the border of the Attic-Cycladic Massif,i.e. on the island of Patmos and Caloyeri, local eruptions of Naalkaline basalts occurred. The whole of the eruptive activity is interpreted as an expression of the marked tensional tectonic phase which has affected the Central Aegean area since Middle Miocene. The contrasting nature of the erupted volcanic rocks (crustal and sub-crustal) is attributed to the different thermal state of the lithosphere beneath the two areas, as emphasized also by the presence of a wide granitic belt, of mainly Miocene age, which developed in the median sector of the Attic-Cycladic Massif.

Metal complexes with macrocyclic ligands. XVI. Spectrophotometric and thermodynamic studies of solvents and unidentate ligands interaction with the pentacoordinate Co2+‐, Ni2+‐ and Cu2+‐complexes of 1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclotetradecane

Abstract: The interaction of solvents and of unidentate ligands such as N, SCN−, OCN− and OH− with the Co2+-, Ni2+ and Cu2+-complexes of 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (TMC) have been studied by Spectrophotometric and calorimetric techniques. The spectra in different solvents (Table 2) show that the Ni2+- and probably also the Cu2+-complex with TMC exist as square planar or pentacoordinate species or as a mixture of both, depending on the donor properties of the solvent. The [Co(TMC)]2+-complex is pentacoordinate in all the solvents studied. Ternary complexes [M(TMC)X]n+ are also formed by the unidentate ligands X = N, OCN−, OH−, F− and NH3 and their stability constants have been determined. Interesting is the high selectivity of [Ni(TMC)]2+ towards the addition of a further donor (Table 3). Only small ligands such as those listed above form stable adducts, whereas the larger ones such as imidazole or pyridine do not. This is a consequence of the special structure of the complex and of the trans-I-(RSRS)- conformation of the ligand in these complexes. Since the four methyl groups are all on the side of the macrocycle to which the additional unidentate ligand binds, steric interaction between the four methyl groups and the larger ligands prevents the formation of the adducts. The calorimetric measurements show that the stability of the complexes [M(TMC)X]n+ is due to both an enthalpic and entropic contribution which differ in their magnitude (Table 4). This indicates that several antagonistic factors are important in determining the overall stability.

Intermittent hypoendorphinaemia in migraine attack

Abstract: Beta-endorphin (RIA method, previous chromatographic extraction) was evaluated in plasma of migraine sufferers in free periods and during attacks. Decreased levels of the endogenous opioid peptide were found in plasma sampled during the attacks but not in free periods. Even chronic headache sufferers exhibited significantly lowered levels of beta-endorphin, when compared with control subjects with a negative personal and family history of head pains. The mechanism of the hypoendorphinaemia is unknown: lowered levels of the neuropeptide, which controls nociception, vegetative functions and hedonia, could be important in a syndrome such as migraine, characterized by pain, dysautonomia and anhedonia. The impairment of monoaminergic synapses ("empty neuron" condition) constantly present in sufferers from serious headaches, could be due to the fact that opioid neuropeptides, because of a receptoral or metabolic impairment, poorly modulate the respective monoaminergic neurons, resulting in imbalance of synaptic neurotransmission.

The effect of taurine on high potassium-and noradrenaline-induced contraction in rabbit ear artery.

Abstract: 1 Intraluminal administration of taurine (40 mM) did not affect the contractile tone of rabbit isolated ear artery 2 Taurine (10-80 mM) exerted a powerful concentration-dependent, vasodilator action in arteries contracted with high potassium medium. 3 In the same experimental conditions, the taurine analogues beta-alanine and homotaurine, had no effect. 4 Taurine (40-80 mM) did not affect in a significant manner the tonic component of the noradrenaline (5x10(-6 M)-induced contraction. 5 When noradrenaline (5x10(-6M) was followed by the administration of high potassium medium a further increase in intraluminal pressure was observed. Under these conditions taurine (40 mM) reversed specifically the component due to the high potassium medium.

Observations on the effects of protease inhibitors on the suppression of experimental allergic encephalomyelitis.

Abstract: Inhibitors of proteolytic enzymes were tested for their ability to suppress the clinical signs and CNS lesions produced by injection of purified myelin in complete Freund's adjuvant into Lewis rats. Pepstatin or a series of neutral protease inhibitors including aprotinin, soybean trypsin inhibitor, leupeptin, antipain, transaminomethyl cyclohexane carboxylic acid (AMCA), ∈-amino caproic acid (EACA) nitrophenyl guanidino benzoate (NPGB),d- andl-polylysine, or a new commercial protease inhibitor, dipropionyl Rhein (DPR) were injected daily beginning on day 7 after immunization of rats with myelin. Aprotinin and soybean trypsin inhibitor exacerbated the symptoms and lesions of experimental allergic encephalomyelitis (EAE), leupeptin and antipain had no effect, and the plasminogen activators AMCA, EACA, NPGB, as well as poly-l- and poly-d-lysine and DPR suppressed various aspects of EAE. The measurement of acid protease as a biochemical method for quantitation of the degree of cellular infiltration into the CNS is proposed, and the results with the various treatments presented. AMCA and NPGB may exert their effects at the site of entrance of the lymphoid cells into the CNS.

Laminar Flow in a Cylindrical Container With a Rotating Cover

Abstract: Unsteady and steady flow in a cylindrical chamber with a rotating cover has been studied for two Reynolds numbers and three aspect ratio values. The structure of the velocity and pressure fields in the apparatus is described. Primary and secondary volumetric flow rates and torque coefficients are also calculated for all six cases solved.

Monoclonal antibodies to the thyrotropin receptor: the identification of blocking and stimulating antibodies

Abstract: Monoclonal antibodies to the thyrotropin (TSH) receptor have been obtained from fusions of mouse myeloma cells with spleen cells immunized with solubilized thyroid membrane preparations. Two monoclonal antibodies which inhibit 125l-TSH binding and are reactive with the glycoprotein component of the bovineTSH receptor (11E8 and 13D11), are shown to inhibit basal and TSH stimulated adenylate cyclase activity in bovine thyroid membranes and human thyroid cells. Both antibodies also inhibit 125l-TSH binding in vitro, whether binding is measured at pH 6.0 in low salts and at 0–4 C or at pH 7.4 in 50 mM NaCl and at 37 C. The glycoprotein component is thus a portion of the physiologic TSH receptor in vivo and 125l-TSH binding studies apparently measure the high affinity glycoprotein component under nonphysiologic conditions and conditions more representative of the physiologic milieu. A third monoclonal antibody whose interaction with thyroid membranes is prevented by TSH is shown to stimulate adenylate cyclase activity in bovine thyroid membranes and human thyroid cells. This stimulating antibody only weakly inhibits 125l-TSH binding to thyroid membranes or to the glycoprotein component of the TSH receptor. The 22A6 antibody does, however, immunoprecipitate mixed brain gangliosides, in distinct contrast to the monoclonal antibodies to the glycoprotein receptor component, i.e., 11E8 and 13D11. The results support the speculation that autoimmune antibodies which inhibit TSH binding to thyroid membranes are not necessarily identical to antibodies which stimulate function; that antibodies directed at the high affinity initial site of TSH interaction with a cell can behave as blocking rather than stimulating antibodies and that a possible relationship exists between stimulating antibodies and the low affinity TSH binding sites (gangliosides) on thyroid membranes.