Showing papers by "University of Siena published in 1987"
TL;DR: The ultrastructure of the cytoskeleton in Nicotiana alata pollen tubes grownin vitro has been examined after rapid freeze fixation and freeze substitution and it is suggested that they are composed of actin and are responsible for generating the vigorous cytoplasmic streaming characteristic of living pollen tubes.
Abstract: The ultrastructure of the cytoskeleton inNicotiana alata pollen tubes grownin vitro has been examined after rapid freeze fixation and freeze substitution (RF-FS). Whereas cytoplasmic microtubules (MTs) and especially microfilaments (MFs) are infrequently observed after conventional chemical fixation, they occur in all samples prepared by RF-FS. Cortical MTs are oriented parallel to the long axis of the pollen tube and usually appear evenly spaced around the circumference of the cell. They are always observed with other components in a structural complex that includes the following: 1. a system of MFs, in which individual elements are aligned along the sides of the MTs and crossbridged to them; 2. a system of cooriented tubular endoplasmic reticulum (ER) lying beneath the MTs, and 3. the plasma membrane (PM) to which the MTs appear to be extensively linked. The cortical cytoskeleton is thus structurally complex, and contains elements such as MFs and ER that must be considered together with the MTs in any attempt to elucidate cytoskeletal function. MTs are also observed within the vegetative cytoplasm either singly or in small groups. Observations reveal that some of these may be closely associated with the envelope of the vegetative nucleus. MTs of the generative cell, in contrast to those of the vegetative cytoplasm, occur tightly clustered in bundles and show extensive cross-bridging. These bundles, especially in the distal tail of the generative cell, are markedly undulated. MFs are observed commonly in the cytoplasm of the vegetative cell. They occur in bundles oriented predominantly parallel to the pollen tube axis. Although proof is not provided, we suggest that they are composed of actin and are responsible for generating the vigorous cytoplasmic streaming characteristic of living pollen tubes.
260 citations
01 Jan 1987
TL;DR: The notion of formal space was introduced by Fourman and Grayson [FG] only a few years ago, but it is only a recent though important step of a long story whose roots involve such names as Brouwer and Stone and whose development is due to mathematicians from different fields, mainly algebraic geometry, category theory and logic.
Abstract: The notion of formal space was introduced by Fourman and Grayson [FG] only a few years ago, but it is only a recent though important step of a long story whose roots involve such names as Brouwer and Stone and whose development is due to mathematicians from different fields, mainly algebraic geometry, category theory and logic.
189 citations
TL;DR: In the bromobenzene-induced liver injury loss of protein thiols as well as impairment of mitochondrial and microsomal Ca2+ sequestration activities are related to lipid peroxidation, however, some redox active compounds such as menadione and t-butylhydroperoxide produce direct oxidation of proteinThiols.
174 citations
TL;DR: Investigating whether some of the methods commonly used to detect lipid peroxidation of cellular membranes in vivo correlate with each other found that they appeared to correlate when applied to in vitro microsomal lipidperoxidation.
Abstract: A study was undertaken to investigate whether some of the methods commonly used to detect lipid peroxidation of cellular membranes in vivo correlate with each other. The study was performed with the livers of bromobenzene-intoxicated mice, in which lipid peroxidation develops when the depletion of glutathione (GSH) reaches a threshold value. The methods tested and compared were the following: i) measurement of the malondialdehyde (MDA) content of the liver; ii) detection of diene conjugation absorption in liver phospholipids; iii) measurement of the loss of polyunsaturated fatty acids in liver phospholipids; and iv) determination of carbonyl functions formed in acyl residues of membrane phospholipids as a result of the peroxidative breakdown of phospholipid fatty acids. Correlations among the values obtained with these methods showed high statistical significances, indicating that the procedures measure lipid peroxidation in vivo with comparable reliability. Analogously, the four methods appeared also to correlate when applied to in vitro microsomal lipid peroxidation.
144 citations
Journal Article•
TL;DR: In vitro studies in which liver sections were incubated in the presence of NADPH-Fe2+, showed a Schiff positivity which increased with the incubation time, confirming the reliability of the histochemical method.
Abstract: The possibility of detecting lipid peroxidation histochemically was investigated in liver tissue in vivo, in conditions in which the process has been demonstrated by biochemical methods. The technique was based on the detection of aldehyde functions with the use of the Schiff's reagent. The study was carried out on bromobenzene-intoxicated mice, which generally exhibit levels of lipid peroxidation considerably higher than those observed in the case of other hepatotoxins. Liver sections from control animals were unstainable by the reagent, while sections from bromobenzene-poisoned mice showed a purple stain of various intensity, unhomogeneously distributed, sometimes with a mediolobular localization. Microphotometric measurements were performed at 565 nm by means of a computer-controlled microscope photometer. The ratios of Schiff-positive area relative to total section area, as well as the total extinctions referred to 100 sq mu of the sections, showed a high correlation with the corresponding hepatic contents of malonic dialdehyde, chosen as biochemical index of lipid peroxidation. In vitro studies in which liver sections were incubated in the presence of NADPH-Fe2+, showed a Schiff positivity which increased with the incubation time, confirming the reliability of the histochemical method. Another procedure, based on the use of 2-OH-3-naphtoic acid hydrazide coupled with fast blue B, was also developed and proved to be possibly more sensitive than Schiff's reagent in the detection of lipid peroxidation in liver tissue.
137 citations
01 Nov 1987-International Journal of Human-computer Studies \/ International Journal of Man-machine Studies
TL;DR: Data is presented on the relationship between types of errors and behavioural patterns of error detection and suggests that different kinds of psychological mechanisms are involved in the detection of different types of error.
Abstract: The way in which humans detect their own errors has been a relatively neglected issue. The following study presents data on the relationship between types of errors and behavioural patterns of error detection, with the aim to define the psychological mechanism that allows the detection of errors. The results suggest that different kinds of psychological mechanisms are involved in the detection of different types of error. Effect of practice as a function of the distribution of attentional resources among levels of control of human behaviour is also discussed.
88 citations
TL;DR: Using rapid freeze fixation and freeze substitution, the ultrastructure of the generative cell wall complex from pollen tubes grown in vitro is re-examined, and the differences are striking.
Abstract: The mature generative cell in pollen grains and pollen tubes is surrounded by a wall complex that includes two plasma membranes, one facing the generative cell cytoplasm and one facing the vegetative cell cytoplasm, and usually some intervening wall material. After conventional chemical fixation, the two plasma membranes are very uneven and often appear to be joined, giving the impression that numerous plasmodesmata connect the vegetative and generative cells. These areas alternate with swollen, distorted areas, which give the wall complex the appearance of being composed of a chain of vesicles. Utilizing rapid freeze fixation and freeze substitution, we have re-examined the ultrastructure of the generative cell wall complex from pollen tubes grown in vitro , and the differences are striking. The two plasma membranes are very smooth and closely appressed to a layer of wall material. Occasionally the wall complex contains swollen areas, or varicosities, and these may contain pockets of lightly stained material, but again the surrounding plasma membranes are tightly appressed to these areas. Plasmodesmata are not seen, but this does not eliminate the possibility that they may exist at an earlier stage of development.
74 citations
TL;DR: In this article, the existence of solutions for the Cauchy problem in a Banach space was proved under hypotheses on F that exclude compactness entirely, assuming that for each (t, X) E Q the closed convex hull of F has a nonempty interior.
73 citations
TL;DR: It seems likely that the liver damage seen during the first phase of bromobenzene-intoxication is strictly related to lipid peroxidation, and it is, however, possible that in some animals in which for some reason lipid per oxidation does not develop, another mechanism of liver necrosis unrelated to lipidperoxidation occurs at later times.
67 citations
TL;DR: The in vivo formation of aldehydes in the liver of animals intoxicated with agents that promote lipid peroxidation has been shown and the biological implications of the finding of 4-hydroxynonenal and other toxic aldeHydes in experimental models of cell injury induced by pro-oxidants are discussed.
62 citations
TL;DR: In this paper, a new compartment, the terrestrial plant biomass, is proposed for inclusion in the fugacity model, and two possibilities of calculation have been developed and exemplified: the first considers the plant as a whole, the second takes into account foliage, trunk and roots separately.
TL;DR: In this paper, the use of plant foliage as an air contamination indicator is discussed and the accumulation and release kinetics from azalea leaves exposed at vapours of (γ- and γ-HCH, p,p′-DDT and DDE, and a PCB mixture (Fenclor 64) are reported.
TL;DR: These studies provide a rational approach to the production of anti-protein MAbs by synthetic peptide immunization and offer the opportunity to obtain MAbs of the desired isotype and affinity.
TL;DR: The total Hg content in soil and in the epiphytic lichen Parmelia sulcata was determined in a former cinnabar mining area on Mt. Amiata as mentioned in this paper.
Abstract: The total Hg content in soil and in the epiphytic lichen Parmelia sulcata was determined in a former cinnabar mining area on Mt. Amiata. Metal concentrations in soil and in lichen are significantly related and decrease at increasing distances from the zone most affected by minespoil and by air which is still vented from mine shafts. On the basis of these results and of Al analysis, it seems likely that anomalous Hg content in Mt. Amiata lichens is mainly due to the out-gassing of volatile Hg from soil, from vegetation and, in the most heavily polluted zone, to the air from mine shafts.
TL;DR: A single dose double‐blind crossover study was performed to compare the efficacy of nedocromil sodium and placebo administered from pressurized aerosols against bronchoconstriction induced by the inhalation of ultrasonically nebulized distilled water (fog).
Abstract: Summary
A single dose double-blind crossover study was performed to compare the efficacy of nedocromil sodium (4 mg) and placebo administered from pressurized aerosols against bronchoconstriction induced by the inhalation of ultrasonically nebulized distilled water (fog) in twelve asthmatic subjects. Neither active nor placebo pre-treatment produced any significant change in baseline FEV1 and SRaw. Nedocromil sodium significantly attenuated fog-induced falls in FEV1 (P < 0.001) and increased specific airways resistance (SRaw, P < 0.01). The results provide further evidence of the potential therapeutic usefulness of nedocromil sodium in the management of chronic obstructive airways disease.
TL;DR: Small all-male groups of rabbits were studied for periods of 15–20 days in a seminatural setting, giving the animals the possibility of initiating and pacing their social interactions, indicating the two as district rather than simply reciprocal traits.
Abstract: Small all-male groups of rabbits were studied for periods of 15–20 days in a seminatural setting, giving the animals the possibility of initiating and pacing their social interactions. Behavioral observations included: intermale activity recorded daily and the reactions to the occasional introduction of an intruder female. Hormones were measured in blood samples taken at the beginning and at the end of the experimental period. A combination of behavioral and endocrine parameters, rather than single measures, was used to assign each individual its social rank within each group. Tables of concordance between behavioral and endocrine parameters were compiled to evaluate the dominance and the subordination hierarchy. Different behavioral categories and elements characterized dominance and subordination, indicating the two as district rather than simply reciprocal traits. Their endocrine basis is also different, final levels of testosterone and estradiol being associated with dominance, and corticosterone, ACTH, and androstenedione with subordination. The same hormones in the initial samples were unrelated to the subsequent social status, indicating that hormones are not prerequisites of status. The relevance of specific behavioral and endocrine parameters is discussed.
TL;DR: The grading systems of gastric dysplasia suffer from the lack of criteria that separate the changes with an acceptable reproducibility, so repeatable and objective grading can be obtained by morphometrically measuring histological criteria normally employed in qualitative grading.
Abstract: The grading systems of gastric dysplasia suffer from the lack of criteria that separate the changes with an acceptable reproducibility. Repeatable and objective grading of the lesion can be obtained by morphometrically measuring histological criteria normally employed in qualitative grading.
In 54 consecutive antrum biopsy specimens in which a blind, independent agreement on the grade of dysplasia had been reached between four independent pathologists, stereological and nuclear morphometrical features have been studied. Single variate, bivariate and multivariate analyses have been performed. Architectural parameters, such as volume and surface densities of glands and epithelium, are especially good discriminators both between mild and moderate, and between moderate and severe dysplasia. Features describing arrangement and shape of nuclei, and nucleolar size are of additional help in improving the objective distinction between moderate and severe dysplasia.
TL;DR: The results suggest that the amount of sleep depends on sleep debt and on the level of pain intensity and sleep stages are differentially sensitive to persistent pain.
Journal Article•
TL;DR: The body distribution of 125I-RTNF shows that most of the radioactivity is concentrated in the kidneys, while lungs do not catabolize TNF at all, while the kidney appears to be the main catabolic organ.
Abstract: We have evaluated the fate of cold and 125I- human recombinant tumor necrosis factor (RTNF) using isolated organs such as rabbit and monkey livers and rabbit kidney and lungs. We have also evaluated the body distribution of the total radioactivity after iv administration of 125I-RTNF in the rabbits. Monkey and rabbit livers play little catabolic role for RTNF. Lungs do not catabolize TNF at all, while the kidney appears to be the main catabolic organ. Accordingly, the body distribution of 125I-RTNF shows that most of the radioactivity is concentrated in the kidneys.
TL;DR: The egg chorion of the Italian species of the genus Electrogena was investigated using the scanning electron microscope (SEM) and showed distinctive chorionic patterns that allowed specific identifications.
Abstract: The egg chorion of the Italian species of the genus Electrogena was investigated using the scanning electron microscope (SEM). The eggs examined showed distinctive chorionic patterns. Electrogena grandiae, E. lateralis and E. zebrata showed attachment structures characterized by knob‐terminated coiled threads (KCTs). These structures were uniformly scattered over the egg surface in E. grandiae, while in E. lateralis they differed in size and position. In E. zebrata, the attachment structures were of uniform size and formed a dense mat over the whole egg surface. In contrast, no specialized sculptures were found in E. fallax and E. gridellii. The different chorionic patterns allowed specific identifications. The affinities and the taxonomic position of the species examined are discussed.
TL;DR: Age, smoking and history of hypertension were the best predictors of the extent and severity of cerebral vessel atherosclerosis.
TL;DR: The epiphytic lichen Parmelia caperata collected in San Rossore park was analyzed for trace elements and the contrast with the results of previous pine needle biomonitoring is discussed.
Abstract: The epiphytic lichen Parmelia caperata collected in San Rossore park was analyzed for trace elements. Metal deposition in the park was found to be low throughout the year. A slight increase in Cu, Co, and Ni occurred at the east-southeastern edge of the park adjacent to Pisa. Lichens ware not affected by the sea-spray which has destroyed the coastal vegetation. The contrast with the results of previous pine needle biomonitoring is discussed.
TL;DR: Evidence, from comparison of observed and calculated spectra, is given to support the existence of a conformational equilibrium between a beta-II and abeta-III reverse turn.
TL;DR: Tissues from the epidermis, alimentary tract and notochord of the cephalochordate Branchiostoma lanceolatum have been examined in both thin sections and freeze-fracture replicas to ascertain the nature of the intercellular junctions that characterize their cell borders.
Abstract: Tissues from the epidermis, alimentary tract and notochord of the cephalochordate Branchiostoma lanceolatum have been examined in both thin sections and freeze-fracture replicas to ascertain the nature of the intercellular junctions that characterize their cell borders. The columnar epithelial cells from the branchial chamber (pharynx), as well as from the anterior and posterior intestine, all feature cilia and microvilli on their luminal surfaces. However, their lateral surfaces exhibit zonulae adhaerentes only. No gap junctions have been observed, nor any tight junctions (as are a feature of the gut of urochordates and higher vertebrates), nor unequivocal septate junctions (as are typical of the gut of invertebrates). The basal intercellular borders are likewise held together by zonulae adhaerentes while hemidesmosomes occur along the basal surface where the cells abut against the basal lamina. The lateral cell surfaces, where the adhesive junctions occur, at both luminal and basal borders, do not exhibit any specialized arrangement of intramembrane particles (IMPs), as visualized by freeze-fracture. The IMPs are scattered at random over the cell membranes, being particularly prevalent on the P-face. The only distinctive IMPs arrays are those found on the ciliary shafts in the form of ciliary necklaces and IMP clusters. With regard to these ciliary modifications, cephalochordates closely resemble the cells of the branchial tract of ascidians (urochordates). However, the absence of distinct junctions other than zonulae adhaerentes makes them exceptions to the situation generally encountered in both vertebrates and urochordates, as well as in the invertebrates. Infiltration with tracers such as lanthanum corroborates this finding; the lanthanum fills the extracellular spaces between the cells of the intestine since there are no junctions present to restrict its entry or to act even as a partial barrier. Junctions are likewise absent from the membranes of the notochord; the membranes of its lamellae and vesicles exhibit irregular clusters of IMPs which may be related to the association between the membranes and the notochordal filaments. Epidermis and glial cells from the nervous system possess extensive desmosomal-like associations or zonulae adhaerentes, but no other junctional type is obvious in thin sections, apart from very occasional cross-striations deemed by some previous investigators to represent ‘poorly developed’ septate junctions.
TL;DR: In chronic liver disease no severe impairment of vitamin D-25-hydroxylation has been observed, except in the latest stages: this is probably due to the great functional reserve of the liver, so that normal levels of serum 25OHD can be maintained on condition that the vitamin D supply is adequate.
TL;DR: Several pathological states such as diabetes, shock, surgery, and rheumatic disease have been described in which an increase of blood viscosity can be observed, and the term ‘syndromes associated with blood hyperviscosity’ could be proposed.
Abstract: Despite the methodological difficulties of evaluating the role of a single rheological component, some clinical situations characterised by an increase of blood viscosity can be identified. These are classified as 'blood hyperviscosity syndromes' and can be divided into 2 groups. The first includes pathophysiological conditions in which a primary blood abnormality causes a decrease of blood flow, as occurs in polycythaemic, sclerocythaemic and seric hyperviscosity syndromes, and may be referred to as 'primary blood hyperviscosity syndromes'. The second group includes pathological conditions in which a primary reduction of blood supply to tissue provokes tissue ischaemia, and an impairment of rheological properties of blood can be observed at microcirculatory level. Thus, these situations have been described as 'secondary blood hyperviscosity syndromes'. Patients with peripheral obliterative arterial disease, ischaemic cardiopathies and cerebrovascular insufficiencies show a diminution in blood fluidity during spontaneous or provoked ischaemic conditions which disappears after reperfusion of the tissue. The pathogenesis of this rheological damage is unclear, but may arise from the complex relationship among blood cells (red cells, leucocytes, platelets), endothelium and plasma components. In addition to these 2 groups of blood hyperviscosity syndromes, several pathological states such as diabetes, shock, surgery, and rheumatic disease have been described in which an increase of blood viscosity can be observed. For these situations, which require much further investigation, the term 'syndromes associated with blood hyperviscosity' could be proposed.
TL;DR: Evidence for defective transport of sialic acid across the lysosomal membrane has been demonstrated in the patient's fibroblasts, and it is possible that this might represent the metabolic abnormality.
Abstract: Increased amounts of free sialic acid were found in cultured fibroblasts and urine of a 4-year-7-month-old Italian boy with mental retardation, hypotonia, failure to thrive, coarse facial features, convergent strabismus, pale skin and fair hair. Ultramicroscopic examination of conjunctival and skin tissues showed a number of membrane-bound vacuoles containing low-density granular material in the cytoplasm of the fibroblasts. The clinical, biochemical and ultrastructural findings are similar to those described in Salla disease. Neuraminidase activity is normal.
TL;DR: The relationships between Ca2+ transport and glucose-6-phosphatase activity, previously studied in isolated liver microsomes, were investigated in permeabilized hepatocytes in the presence of mitochondrial inhibitors and it was found that the addition of glucose 6-ph phosphate to the cells markedly stimulates the MgATP-dependent Ca2-dependent uptake.