Showing papers by "University of Siena published in 1976"
TL;DR: The authors distinguish the keratin-like proteins of sperm accessory fibers of mammals and cephalopods with the new name of parergins withThe occurrence of low-Sulfur and high-sulfur polypeptides, the zinc-binding properties, and the analogous localization in wave-generating flagella prompt the authors to distinguish.
77 citations
TL;DR: The accessory fibers account for the highest percentage of sulfhydryl groups in both mammalian and cephalopod sperm and are involved in the binding of zinc, according to electron probe microanalysis and biochemical studies on fibers purified by density step centrifugation.
71 citations
TL;DR: The role of sialic acid in determining the life of circulating cells and glycoproteins is reviewed and an attempt is made to assess its real importance and to interpret the desialylation pathway.
Abstract: The role of sialic acid in determining the life of circulating cells and glycoproteins is reviewed and an attempt is made to assess its real importance and to interpret the desialylation pathway. An overall view of factors, including desialylated glycoprotein fragments, that may regulate hepatic synthesis of glycoproteins is presented.
70 citations
TL;DR: Within the technical frame supplied by the algebraic variety of diagonalizable algebras, defined by R. Magari in this paper, it is shown that the following can be obtained:
Abstract: Within the technical frame supplied by the algebraic variety of diagonalizable algebras, defined by R. Magari in [2], we prove the following:
69 citations
TL;DR: The development of the transmitting tissue of the style of Lycopersicon peruvianum goes, after the completion of cell division and cell wall formation, through two distinct phases, and a possible role of these proteins in the incompatibility reaction is proposed.
Abstract: The development of the transmitting tissue of the style of Lycopersicon peruvianum goes, after the completion of cell division and cell wall formation, through two distinct phases. During the first phase, the cells enlarge and the main part of the intercellular substance, consisting of pectins, is formed. During the second phase, the cells form an extensive rough endoplasmic reticulum (RER) and proteins are incorporated in the intercellular substance. A possible role of these proteins in the incompatibility reaction is proposed.
58 citations
TL;DR: The results suggest that flagellar movement is dependent on the presence of dynein arms but is independent of the ninefold symmetry pattern of a sperm tail.
54 citations
TL;DR: The outer surface of the plasma membrane in the egg of Xenopus laevis is described by means of scanning electron microscopy and freeze-etching techniques: extensive rearrangement of the surface occurs following fertilization and during the first cleavage divisions.
49 citations
43 citations
TL;DR: Elements resistent to alteration and metamorphism from metabasalts samples belonging to the north Apennine ophiolites have been determined in order to investigate the primary tectonic environment of these rocks.
41 citations
TL;DR: The giant size of the spermatozoon of Divales bipustulatus prompted an investigation of its ultrastructure and found that most of the tail is occupied by 2 symmetrical mitochondrial derivatives with a complex inner organization.
Abstract: The giant size of the spermatozoon of Divales bipustulatus prompted an investigation of its ultrastructure. The sperm tail is about 10 mn long and has a maximal thickness of 3.5 μm near its distal end. Most of the tail is occupied by 2 symmetrical mitochondrial derivatives with a complex inner organization. There are also 2 accessory bodies, 2 accessory sheaths and an axoneme, all of which extend together with the mitochondrial derivatives throughout the length of the sperm tail.
30 citations
TL;DR: In this article, it is known that in Peano arithmetic, there exists a formulaTheor (x) which numerates the set of theorems and, up to provable equivalence, only one solution.
Abstract: It is well known that, in Peano arithmetic, there exists a formulaTheor (x) which numerates the set of theorems. By Godel's and Lob's results, we have that
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Therefore, the considered «equations» admit, up to provable equivalence, only one solution.
TL;DR: Cell surface changes occurring before and during gastrulation in Xenopus laevis embryos have been examined by scanning electron microscopy to discuss changes in cell-to-cell connections and to the role of cell surface organization in the morphogenetic movements of gastrulations.
TL;DR: The electrochemical reduction of triphenyltin chloride at mercury electrodes in acetonitrile solution has been studied by cyclic voltammetry, polarography and controlled potential coulometry.
TL;DR: The pyloric region of Eosentomon and Acerentomon (Insecta, Protura) is described and it is suggested that the R2 region represents a basic excretory region, common to Protura, whereas the R1 region, in EOSentomon, may be a specialized area performing supplementary excreteory functions.
Abstract: The pyloric region of Eosentomon and Acerentomon (Insecta, Protura) is described. In both species the posterior cells of the midgut carry short microvilli. Beneath the epithelial cells there is a muscular pyloric sphincter for closing the intestinal lumen. Behind the sphincter is a wide pyloric chamber lined by cells with very long microvilli which point anteriorly toward the midgut. These cells regulate the passage of the intestinal contents into the hindgut. Secretions from the Malpighian papillae are emitted into the gut at this level. In Eosentomon three regions (R1 , R2 and R3 ) are visible in the Malpighian papillae, whereas in Acerentomon region R1 is lacking. The R1 region contains secretory cells with elaborate glycoprotein-containing granules. The R2 region is composed of cells somewhat resembling the secretory cells of Malpighian tubules of insects. Presumably R1 and R2 cells emit secretions into the central cavity of each papilla. Cells of R3 form a duct for the secretion. It is suggested that the R2 region represents a basic excretory region, common to Protura, whereas the R1 region, in Eosentomon, may be a specialized area performing supplementary excretory functions.
TL;DR: An association between plastids and ER cisterns (PER) was observed during a well-defined period of pollen grain development in Lycopersicon peruvianum and the meaning of these findings is discussed.
TL;DR: The fine structure of the egg shell of the neuropteran Chrysopa carnea is described by transmission and scanning electron microscopy with particular attention to the micropylar area and chorion.
Abstract: This paper describes the fine structure of the egg shell of the neuropteran Chrysopa carnea by transmission and scanning electron microscopy. Particular attention has been directed to the structure of the micropylar area and chorion. The micropylar region consists of a circular area with 30 semicircular channels, each corresponding to a micropylar orifice, localized at the apical pole of the egg. The endochorion of C. carnea consists of plurilaminar layers, each made up of subunits periodically arranged, parallel to the egg surface.
TL;DR: Mussels from the Paglia River in Italy were analyzed for mercury and found that in the larger individuals, the digestive gland had the highest concentration and the muscle the lowest.
Abstract: Mussels from the Paglia River in Italy were analyzed for mercury. Total mercury concentration in the shell of the mussel, Unio cfr. elongatulus, did not exceed 0.2 ppM with an average of 0.12 ppM. In the whole soft parts of the 15 small individuals the Hg concentration ranged from 0.192 ppM to 0.385 ppM. In the larger individuals, the digestive gland had the highest concentration and the muscle the lowest.
01 Jan 1976
TL;DR: In this article, a stratigraphic outline of the Paleozoic-Triassic is presented, based on a study of metamorphism of the region, based in particular on the bo value of the potassic mica.
Abstract: This paper present: a stratigraphic outline of the Paleozoic-Triassic. Formations that crop out south of the Arno River; a hypothesis regarding their correlation with the M.Pisano sequence north of the Arno; and conclusions about their position in the tectonic evolution of the Hercynian and Alpine cycles. These conclusions were also based on a study of the metamorphism of the region, based in particular on the bo value of the potassic mica.
01 Jan 1976
TL;DR: Variations of the size of pools during activity and rest are in part responsible for the large fluctuations of protein concentration observed for some plasma proteins.
Abstract: In steady-state conditions, the amount of protein synthesized is equivalent to the amount of protein broken down daily, so that concentration in the plasma remains fairly constant. As a matter of fact, the rate of synthesis may change considerably during the day owing to periods of digestion or sleep, or to the effect of endogenous regulatory factors, and similar changes probably occur for the catabolic process. Moreover, variations of the size of pools during activity and rest are in part responsible for the large fluctuations of protein concentration observed for some plasma proteins.
TL;DR: In this article, the cathodic behaviour of phenylbenzoate was investigated in an aprotic solvent (DMF) both at platinum and mercury electrodes and the main techniques employed were cyclic voltammetry, chronoamperometry and controlled potential coulometry.
01 Oct 1976
TL;DR: The hypothesis that certain protein characteristics are modified differently during the storage phase is discussed, and the contents of the rough endoplasmic reticulum also was found to be soluble in NaCl.
TL;DR: Bovine synthetic parathyroid hormone infused intravenously in man increased both the urinary excretion of cyclic AMP and the urinaryexcretion of phosphate whereas a Salmon synthetic calcitonin infusion increased the urinaryExcretation of phosphate without change in urinary excretions.
Abstract: Bovine synthetic parathyroid hormone infused intravenously in man increased both the urinary excretion of cyclic AMP and the urinary excretion of phosphate whereas a Salmon synthetic calcitonin infusion increased the urinary excretion of phosphate without change in urinary excretion of cyclic AMP. These data are consistent with the hypothesis that different renal mechanisms are involved in the response to each hormone.
TL;DR: The number of mitoses as well as the number of the cells of the adrenal medulla was determined in the mouse at various ages and after unilateral adrenalectomy and found that a decrease in the mitoses and an increase in the cell number occurs up to 4 months.
Abstract: The number of mitoses as well as the number of the cells of the adrenal medulla was determined in the mouse at various ages and after unilateral adrenalectomy. It was found that a decrease in the mitoses and an increase in the cell number occurs up to 4 months. In 12-month-old rats, mitoses, although rare, are still present. No changes in the mitosis and cell number was observed after unilateral adrenalectomy.
TL;DR: The wave corresponding to the reduction of uranium(VI) to uranium(IV) is well shaped, diffusion-controlled, and can be used for the determination of uranium down to 2 x 10 (-5)M or 3 x 10(-6)M if a rotating electrode is used.
01 Jan 1976
TL;DR: The health autorities in the different countries require a detailed pharmacokinetics analysis for accepting a new drug and most of the leading drug companies have developed laboratories of Pharmacokinetics.
Abstract: The theory of compartments represents the mathematical basis of the study of pharmacokinetics. The application of such a theory to the problems of drug kinetics, that is to the study of the movements followed by drug in the organism, in isolated organs or apparatuses, began with the paper of Gehlen (1), followed by those of Teorell (2) and of Beccari (3). After the second world war the theory was clearly stated and applied with its different derivations by several Authors: Dost (14), Rescigno and Segre (5), Atkins (6), Notari (7), Wagner (8), Jaquez (9), Gladtke (10). Symposia have been held on this topic (11,12) and scientific journals have been published on pharmacokinetics (J. of Pharmacokinetics and Biopharmaceutics, Clinical Pharmacokinetics), whereas a high proportion of the papers which appear in the journals of clinical pharmacology are dealing essentially with problems of pharmacokinetics. The health autorities in the different countries require a detailed pharmacokinetics analysis for accepting a new drug and most of the leading drug companies have developed laboratories of pharmacokinetics.
TL;DR: The results are compatible with the evidence that there is a weak intestinal transport mechanism for EHDP, a high rate of urinary excretion and a sustained retention within the body in a compartment outside the blood.
TL;DR: The plasma level of cAMP increased sharply in all subjects within 10min of the start of the bPTH infusion, and the urinary cAMP/Cr ratio and the CcAMP/CCr ratio increased in all cases within 20min.
Abstract: Infusion of bovine parathyroid hormone (bPTH): The effects of bPTH (1-34) infused intravenously (200-400 units infused over 10rain) on plasma calcium, urinary calcium (expressed as the Ca/Cr ratio), urinary phosphate (expressed as the PO4/Cr ratio), plasma cAMP, urinary cAMP (expressed as the cAMP/Cr ratio) and the ratio between the clearance of cAMP and endogenous creatinine clearance (CcAMP/CCr) were measured in 6 normal subjects, in 1 patient with idiopathic hypoparathyroidism and in 1 patient with Paget's disease. The hypercalcemic effect of the bPTH was evident in all subjects, the maximum effect occurring within 2-4h. A sharp increase in plasma calcium was observed within the first 5min followed by a decrease within 10rain in 7 of the 8 subjects. Urinary Ca/Cr ratio did not change significantly in. 7 patients and a clear-cut diminution was observed in 1. The plasma level of cAMP increased sharply in all subjects within 10min of the start of the bPTH infusion. Both the urinary cAMP/Cr ratio and the CcAMP/CCr ratio increased in all cases within 20min. The PO4/Cr ratio rose progressively following the peak in urinary cAMP (from about 20-30 min). It paralleled a slight fall in plasma PO4 level.
TL;DR: 56 main areas are discussed which are in urgent need of protection from commercial speculation and the threat of irreparable damage and the authors hope that national and international public opinion will encourage the Italian Government to establish many more protected territories and to provide the resources for realistic management.