Showing papers by "University of Siena published in 1991"

The Aeromonas hydrophila cphA gene: molecular heterogeneity among class B metallo-beta-lactamases.

Abstract: An Aeromonas hydrophila gene, named cphA, coding for a carbapenem-hydrolyzing metallo-beta-lactamase, was cloned in Escherichia coli by screening an Aeromonas genomic library for clones able to grow on imipenem-containing medium From sequencing data, the cloned cphA gene appeared able to code for a polypeptide of 254 amino acids whose sequence includes a potential N-terminal leader sequence for targeting the protein to the periplasmic space These data were in agreement with the molecular mass of the original Aeromonas enzyme and of the recombinant enzyme produced in E coli, evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of crude beta-lactamase preparations followed by renaturation treatment for proteins separated in the gel and localization of protein bands showing carbapenem-hydrolyzing beta-lactamase activity by a modified iodometric technique The deduced amino acid sequence of the CphA enzyme showed regions of partial homology with both the beta-lactamase II of Bacillus cereus and the CfiA beta-lactamase of Bacteroides fragilis Sequence homologies were more pronounced in the regions encompassing the amino acid residues known in the enzyme of B cereus to function as ligand-binding residues for the metal cofactor The CphA enzyme, however, appeared to share a lower degree of similarity with the two other enzymes, which, in turn, seemed more closely related to each other These results, therefore, suggest the existence of at least two molecular subclasses within molecular class B metallo-beta-lactamases

Pollen viability and pollen vigor

Abstract: Investigations were carried out to correlate pollen viability, assessed on the basis of a fluorochromatic reaction (FCR) test, with pollen vigor, assessed on the basis of the time taken for in vitro germination in pollen grains subjected to high humidity (>95% RH) and temperature (38 °C) or storage stress of Nicotiana tabacum, Agave sp., Tradescantia virginiana, and Iris sp. Both high RH and temperature, as well as storage stresses, affected pollen vigor before affecting pollen viability. The results are discussed in the light of available data on the viability and vigor of stressed pollen and of aged seeds. The need for consideration of pollen vigor, particularly in stored pollen, the inadequacy of the methods presently used, and some of the methods suitable to assess pollen vigor are elaborated.

The role of bacteria in pigment gallstone disease.

Abstract: One hundred ten of nine hundred sixty consecutive patients who underwent surgery for gallstones (GS) had pigment stones (PS) (11.45%). Fifty brown PSs contained calcium bilirubinate, small amounts of cholesterol, and always calcium palmitate, were usually found in the common duct (96%), and were almost always associated with bile infection (98%) and diffuse erosion of the biliary mucosa. Fifty-one black PSs contained bilirubin polymers, calcium carbonate, and/or phosphate, seldom cholesterol, and never evident amounts of calcium palmitate, were mostly found in the gallbladder, and were associated with hemolysis or liver damage and with hyperplastic cholecystosis. Bile infection was found in 19.6% of cases, but bacteria were never found in the center of black PSs by scanning electron microscopy. Nine additional patients (8.2% of PSs, 0.9% of GSs) had concomitant black and brown PSs that were mostly found in the common duct and were always associated with bile infection. It is suggested that, even if PSs with concomitant black and brown material can be found, black and brown PSs greatly differ not only in pathogenesis but also in clinical behavior and treatment. In particular bacterial infection is important only in the pathogenesis of brown PSs while it plays no role in the initial formation of cholesterol, mixed or black GSs.

Interleukins. Clinical pharmacokinetics and practical implications.

Abstract: Interleukins and tumour necrosis factor (TNF) are a complex group of proteins and glycoproteins able to exert pleiotropic effects with respect to a number of different target cells. In physiological conditions, they are induced and released in basal amounts only in restricted microenvironments where they have paracrine activity. Any small amounts reaching the circulation do not disturb homoeostasis. During therapy, particularly when these cytokines are administered via conventional routes, it has become apparent that their presence in nonphysiological plasma concentrations and their unselective action cause toxic effects with small benefits. The pharmacokinetics of interleukins-1, -2, -3 and -6 and TNF have been evaluated, and their disappearance from plasma after intravenous administration is very rapid (i.e. the distribution half-life is measured in minutes; the elimination half-life is several hours). The efficiency of catabolic pathways such as renal filtration and/or liver uptake is interpreted as a salutary mechanism for extracting proteins that should not be in the circulation. However, because these cytokines are very potent immunomodulatory agents there is a need to improve their therapeutic index, and to this end a number of possible formulations and routes of administration are now available and may eventually be of practical use.

Isolation of male and female gametes in higher plants.

Abstract: The availability of generative cells, sperm cells, embryo sacs and egg cells from angiosperm plants in isolated conditions has opened up many prospects: study of the mechanism of recognition and fusion between gametes of opposite sex and detailed observation of the process of fertilization, biochemical and genetic analysis of gamete-specific components and genetic engineering in combination with in vitro fertilization. This review provides a list of about ninety publications, in which the isolation of male or female angiosperm gametes and the closely related generative cells and embryo sacs is reported. The species used are summarized in two tables. A description is given of the diverse isolation techniques, which consist of enzymatic digestion, bursting of pollen by osmotic shock, squashing, grinding and micro-dissection. Viability of isolated cells and yield, two important aspects of biotechnological manipulation, are emphasized. A critical evaluation of the most significant results obtained so far with isolated material is presented together with notes on prospects for the future.

Glutathione depletion: its effects on other antioxidant systems and hepatocellular damage.

Abstract: 1. The mechanisms of the liver damage produced by three glutathione (GSH)-depleting agents, bromobenzene, allyl alcohol and diethyl maleate, were investigated. 2. With each toxin liver necrosis was accompanied by lipid peroxidation that developed only after severe depletion of GSH. 3. Changes in antioxidant systems by alpha-tocopherol (vitamin E) and ascorbic acid were studied. A decrease in the hepatic level of vitamin E, and a change in the redox state of vitamin C (increase in oxidized over reduced form) were evident whenever extensive lipid peroxidation developed. However, in the case of bromobenzene intoxication these alterations preceded lipid peroxidation, and may be an index of oxidative stress leading to subsequent membrane damage. 4. Experiments carried out with vitamin E-deficient or supplemented diets indicated that pathological phenomena occurring as a consequence of GSH depletion depend on hepatic levels of vitamin E. In vitamin E-deficient animals, lipid peroxidation and liver necrosis appeared earlier than in animals fed the control diet. In animals fed a vitamin E-supplemented diet, bromobenzene and allyl alcohol had only limited toxicity, and diethyl maleate none, in spite of similar hepatic GSH depletion. Thus, vitamin E may largely modulate the expression of toxicity by GSH-depleting agents.

A case-control study of gastric cancer and diet in Italy. III. Risk patterns by histologic type.

Abstract: In a case-control study of gastric cancer (GC) in high-risk and low-risk areas of Italy, 923 GCs were systematically categorized by one pathologist according to the Lauren classification distinguishing 2 main histologic types, intestinal (55%) and diffuse (23%). Intestinal types outnumbered diffuse types by a 3 to I margin in high-risk regions in the north-central part of the country, while both types occurred at nearly equal rates in low-risk areas. Intestinal types also occurred relatively more frequently at older ages and among males. Relative risks of each type of GC were evaluated In relation to dietary and other data obtained from interviews with the cancer patients and controls. The risk patterns for intestinal and diffuse types were remarkably similar. Increased risks of both types were associated with high intake of meat, salted/dried fish, seasoned cheeses and traditional soups, while decreased risks of both types were found among heavy consumers of fresh vegetables and fruits. Correspondingly similar patterns were seen with indices of nutrients, with risks of both intestinal and diffuse GC rising with animal protein Intake and declining with consumption of vitamins C and E. Both types were inversely related to socio-economic status, and neither was associated with cigarette smoking. A familial history of GC was reported more frequently by patients with each type than by controls, although the highest risk was for unclassified GC, a group of poorly differentiated and medullary carcinomas accounting for 15% of all GCs in this study. The findings suggest that, despite differences in geographic and demographic patterns, the intestinal and diffuse types of GC have etiologic factors in common.

Use of calcitonin in the treatment of bone pain associated with osteoporosis.

Abstract: In osteoporosis, calcitonin exerts an analgesic effect that is unrelated to its effect on bone. Although the precise mechanism has yet to be clarified, there is some evidence that the analgesic effect of calcitonin may be mediated through the endogenous opioid system. The intranasal administration of calcitonin seems to be more effective in producing analgesia than parenteral administration.

Property rights, asset specificity, and the division of labour under alternative capitalist relations

Abstract: Is the division of labor under capitalism because of transaction and technological efficiency or because of inefficient capitalist property rights? The answer of this paper is that under "classical" capitalism there is an inefficient division of labor because of underinvestment in asset-specific labor which can be improved by expanding workers' rights in two different ways defining "company workers" and "unionized" capitalism. An implication of the analysis is that markets, far from being the selection mechanism where efficient institutions evolve, may imply the reproduction of inefficient property rights and be shaped by them. Copyright 1991 by Oxford University Press.

The Reactivity of the Sh Group of Bovine Serum Albumin with Free Radicals

Abstract: The reactivity of the SH group of bovine serum albumin (BSA) towards free radicals generated by several different systems including gamma-radiolysis and hydrogen peroxide/metal salt mixtures was investigated. On exposure of BSA (1 mg/ml and 5 mg/ml) to HO. radicals generated radiolytically the protein-SH concentration was found to decrease in a dose-dependent manner. At 40 mg/ml albumin no loss of SH was observed. O2-. and HO2. radicals were much less aggressive towards the SH group. The effect of divalent metal salts (copper or iron) plus hydrogen peroxide was studied separately and in combination. H2O2 alone caused a decrease in SH group concentration the rate of which was not decreased by the presence of desferrioxamine and so was apparently not due to reactions catalysed by adventitious metal ions. Copper alone caused a dose-dependent decrease in SH group concentration and the mixture of the two agents caused a greater loss of SH than each separate component. However, this latter effect was again resistant to the effects of desferrioxamine. The SH group of BSA was only moderately sensitive to the presence of ferrous iron alone and in a system containing both ferrous iron and H2O2 rates of SH oxidation were obtained that were identical to those obtained with H2O2 alone. Desferrioxamine again did not alter the rate of SH oxidation in these experiments. We suggest that the highly reactive free radical HO. is not able to reach and to oxidize the SH group of BSA when generated by metal/H2O2 mixtures, in contrast to HO. generated radiolytically. Less reactive radicals and non-radical species such as H2O2 have more potential for doing so.

Studies on the biological effects of ozone: 2. Induction of tumor necrosis factor (TNF-alpha) on human leucocytes.

Abstract: The effect of ozone as a probable inducer of tumor necrosis factor (TNF-alpha) has been investigated on human blood and on Ficoll-purified blood mononuclear cells (PBMC). Samples were exposed at different ozone concentrations ranging from 2.2 to 108 micrograms/ml and incubated at 37 degrees C in an 95% air-5% CO2 atmosphere. At predetermined times, all cell supernatants were tested for TNF activity and some PBMC cultures were examined for DNA synthesis. The authors have shown that ozone concentration is critical in terms of TNF production and of cell mitogenesis and that, owing to the presence of erythrocytes, higher ozone concentrations are required to be effective in blood than in PBMC. Because ozonization of blood is a procedure followed in several European countries for the treatment of viral diseases and tumors, the release of factors with antiviral and immunomodulatory activities by leukocytes may explain the mechanism of action of ozone and of autohemotherapy.

Inhibin and activin modulate human monocyte chemotaxis and human lymphocyte interferon-gamma production.

Abstract: Inhibin and activin are referred to as gonadal glycoprotein hormones whose function is the control of FSH release from the pituitary gland. However, several observations indicate that inhibin and activin are produced in various organs and serve multiple functions. Because bone marrow and spleen produce inhibin and activin, our aim was to evaluate their possible effect on cell-mediated immune function. For this reason we studied 1) monocyte chemotaxis, 2) lymphocyte interferon-gamma production, 3) phytohemagglutinin-induced lymphocyte proliferation, and 4) nonmajor histocompatibility complex-restricted and lymphokine-activated lymphocyte cytotoxicity. All studies were performed on human peripheral blood cells in the absence or presence of various doses of inhibin, activin, or inhibin plus activin. A significant dose-related increase in monocyte chemotaxis was induced by inhibin. Activin increased the migrational activity of monocytes, but via random, not directed, migration. Inhibin significantly decreased interferon-gamma production, and its effect was reversed by activin. Inhibin and/or activin had no significant effect on either phytohemagglutinin-induced lymphocyte proliferation or lymphocyte cytotoxic capability. The present demonstration that inhibin and activin may affect some immune parameters suggests a possible involvement of these hormones in regulating cell-mediated immune function.

Secretory tapetum of Brassica oleracea L.: polarity and ultrastructural features

Abstract: The ultrastructure of the secretory, binucleate tapetum of Brassica oleracea in the micro spore mother cell (MMC) stage through to the mature pollen stage is reported The tapetal cells differentiate as highly specialized cells whose development is involved in lipid accumulation in their final stage They start breaking down just before anther dehiscence Nuclei with dispersed chromatin, large nucleoli and many ribosomes in the cytoplasm characterize the tapetal cells The wall-bearing tapetum phase ends at the tetrade stage The dissolution of tapetal walls begins from the inner tangential wall oriented towards the loculus and proceeds gradually along the radial walls to the outer tangential one The plasmodesmata transversing the radial walls between tapetal cells persist until the mature microspore, long after loss of the inner tangential wall After wall dissolution, the tapetal protoplasts retain their integrity and position within the anther locule The tapetal cell membrane is in direct contact with the exine of the microspores/pollen grains and forms tubular evaginations that increase its surface area and appear to be involved in the translocation of solutes from the tapetal cells to the microspores/ pollen grains The tapetal cells exhibit a polarity expressed by spatial differentiation in the radial direction

Photosensitizing action of furocoumarins on membrane components and consequent intracellular events

Abstract: The photodamage induced in membrane components by furocoumarins is reviewed. The oxygen-dependent photoreactions between furocoumarins and cell membrane constituents lead mainly to lipid peroxidation and the formation of cross-linking in ghost proteins, whereas the oxygen-independent photoreactions lead essentially to a C4 cycloaddition between the furocoumarin and the unsaturated fatty acids. In the latter, cycloadducts are formed between the 3,4 double bond of the furocoumarin and the olefinic double bond of the unsaturated fatty acid. The stereochemical structures of these cycloadducts and the reaction mechanism of the cycloaddition are discussed. Finally, the modulation of several membrane systems by furocoumarins and the consequent intracellular events are reviewed.

Lichen biomonitoring of mercury emission and deposition in mining geothermal and volcanic areas of italy

Abstract: Natural emissions of Hg are attracting increased interest both for their environmental implications and for possible applications in the exploration of mineral, petroleum and geothermal fields. However, daily and seasonal fluctuations in concentrations of Hg in the atmosphere, caused by meteorological and environmental variables, has made it very difficult to assess Hg anomalies by conventional analytical procedures. Some species of widespread foliose lichens from an abandoned cinnabar mining and smelting area (Mt. Amiata), geothermal fields (Larderello, Bagnore and Piancastagnaio, Central Italy), and active volcanic areas (Mt. Etna and Vulcano, Southern Italy) seem to be very suitable biomonitors of gaseous Hg; especially as lichen thalli have an Hg content which reflects average values measured in air samples. We discuss the advantages of quantitative biological monitoring by lichens with respect to conventional air sampling in large-scale monitoring.

Expression of α‐sooth‐muscle actin in stromal cells of the uterine cervix during epithlial neoplastic changes

Abstract: A total of 55 formalin-fixed and paraffin-embedded specimens of normal, inflamed and neoplastic uterine cervix have been studied in order to correlate the epithelial changes with the expression of alpha-smooth-muscle actin in stromal cells. This actin isoform is typical of smooth-muscle cells, but appears also temporarily in fibroblasts during wound healing and permanently during fibrocontractive diseases and stromal reaction to epithelial tumors. While positive stromal cells were absent in normal and inflamed cervix, they accumulated in relation to neoplastic tissues. The number of alpha-smooth-muscle actin positive cells and the intensity of stain were related to the increasing grading of cervical intra-epithelial neoplasia. Our results suggest that alpha-smooth-muscle actin is a marker of stromal-cell reaction to the development of neoplastic lesions. The evaluation of alpha-smooth-muscle actin in stromal cells of the uterine cervix may be a useful adjunct to diagnostic criteria of cervical intra-epithelial neoplasia and may help understanding of the mechanisms of mesenchymal-epithelial interactions during neoplasia.

Responses of tobacco pollen to high humidity and heat stress: viability and germinability in vitro and in vivo

Abstract: Responses of pollen grains of Nicotiana tabacum to high humidity (95% RH, 4 h) and temperature (38°/45° C, 4 h) stresses were investigated. Pollen grains were subjected to only RH or only temperature, or to both of these stresses. Their viability was assessed on the basis of the fluorochromatic reaction (FCR) test, and vigour was assessed on the basis of the time taken for in vitro germination as well as on the emergence of pollen tubes through the cut end of semi-vivo implanted styles. None of the stress conditions affected pollen viability and high RH or high temperature stress did not individually affect pollen vigour. However, pollen vigour was markedly affected when both the stresses were given together. Pollen grains subjected to high RH at 38° C took a longer time to germinate in vitro and the pollen tubes emerged later from the cut end of the semi-vivo styles; division of the generative cell was also delayed. Pollen grains subjected to high RH at 45° C failed to germinate in vitro, but did germinate on the stigma. Many pollen tubes subjected to this treatment showed abnormalities, and the growth of pollen tubes in the pistil was much slower than that observed in other treatments. Pollen samples subjected to all of the stress conditions were able to induce fruit and seed set. The implications of these results on the relationship between the FCR test and viability, and between viability and vigour, especially in stressed pollen, are discussed.

Absorption of cytokines via oropharyngeal-associated lymphoid tissues. Does an unorthodox route improve the therapeutic index of interferon?

Abstract: Recent data have suggested the possibility of stimulating the immune system by administering physiological doses of IFN via the oropharyngeal tissues. If these results can be confirmed, there will be millions of patients with acute and chronic viral diseases, residual minimal disease and immune depression able to take advantage of an extremely simple, inexpensive and well tolerated therapeutic modality. This approach only appears to be new and probably operates in the development of the immature immune system during the breast-feeding period. However, despite this and despite a rational background reviewed here, since this proposal does not fit conventional schemes, it has (correctly) been met with remarkable scepticism and prejudice. The aim of this article has been to point out that there are anatomical, immunological and pharmacological data suggesting that the approach is meaningful. Appropriate double-blind clinical trials are needed to prove its validity.

Central beta-endorphin system involvement in the reaction to acute tonic pain.

Abstract: The involvement of the beta-endorphin (B-EP) system during acute prolonged (tonic) pain was investigated by biochemical and behavioral approaches in freely-moving rats after subcutaneous injection of a small amount of a dilute formaldehyde solution (0.08 ml, 5%) in a forepaw. Beta-endorphin-like immunoreactivity levels were increased over the respective control groups in rats killed 30, 60 and 120 min after injection in discrete regions of the rat brain, namely ventro-medial hypothalamus, ventro-basal thalamus and periaqueductal gray matter, and at 30 and 60 min in postero-medial thalamus. In a separate group of experiments a small amount of anti-B-EP or normal rabbit serum was injected in the lateral ventricle; 6 h later rats received formalin injection as in previous groups and their behavior was scored over the following 2 h. A significant hyperalgesia (as expressed by an increase in the amount of time rats spent licking or chewing the injected paw) was observed 10–50 min and 70–80 min after formalin in the anti-B-EP icv-injected group. Other behavioral parameters such as general motor activity, grooming and limb flexion were not different in the two groups, nor was animal behavior prior to formalin injection. Altogether these data suggest that the central beta-endorphin system is triggered by prolonged noxious stimulation in freely-moving animals, and in turn plays a physiological role in the modulation of the reaction to, or perception of, tonic pain.

Immunohistochemical localization of IL-1 alpha and IL-1 beta in normal human placenta.

Abstract: Many reports show that interleukin 1 (IL-1) is produced by mouse and human placenta but the cell type that is responsible for this production has yet to be identified. For this reason we attempted to localize IL-1 alpha and IL-1 beta directly on formalin-fixed paraffin-embedded normal human placentae at different stages of pregnancy using immunohistochemical techniques and specific antibodies. The results obtained show that both IL-1 forms are localized to villous syncytiotrophoblast and to extravillous trophoblast, while villous cytotrophoblast and cytotrophoblast columns are unreactive. A gradual decrease of reactivity was observed with increasing gestation age for both IL-1 forms, but the staining for IL-1 beta was in all sections higher than for IL-1 alpha. Although the physiological role of IL-1 in pregnancy has yet to be established, the presence of this cytokine in the cells facing maternal blood and tissues suggests a possible involvement in the immunoregulation of fetal acceptance.

Presence of homonymous recurrent inhibition in motoneurones supplying different lower limb muscles in humans

Abstract: The pattern of recurrent inhibition to motoneurones (MNs) innervating different lower limb muscles was investigated in ten healthy subjects. Three complementary experimental designs, all based on the electrophysiological method introduced by Bussel and Pierrot-Deseilligny in 1977, were used in Quadriceps (Qu), Pretibial (Pt), Soleus (Sol) and Abductor hallucis (Abh) motornuclei: 1) measurement of the relationship between the amplitude of conditioning H (H1) and test (H′) reflexes; 2) measurement of the effect of the intravenous administration of L-Acetylcarnitine (L-Ac) on the amplitude of the test H′ reflex after a constant H1 conditioning reflex; 3) measurement of the modifications of the test H′ reflex in relation to a reference H (Ref H) reflex during a weak tonic voluntary contraction of the homonymous muscle. A complete agreement among results obtained with the different experimental paradigms was observed. Similarly to the Sol, both Pt and Qu MNs were found to be recurrently inhibited: a) the test H′ reflex exhibited a progressive and consistent depression with increasing amplitude of the H1 conditioning reflex beyond a specific value; b) an additional decrement of the test H′ reflex was obtained after intravenous administration of L-Ac; c) a decrease in the size of the test H′ reflex, with respect to its value at rest, was observed during a weak tonic voluntary contraction, in spite of the enhanced MN excitability (as shown by the increase in the Ref H). By contrast, no evidence of recurrent inhibition to the Abh MNs was found. The amplitude of the test H′ reflex showed no further depression with increasing conditioning reflex discharge, L-Ac administration or during weak voluntary contraction. It is concluded that in the lower limb, MNs acting on the knee and ankle muscles receive recurrent inhibition, but that this is lacking in motornuclei innervating the more distal muscles, such as the intrinsic foot muscles. Some methodological and physiological implications are discussed in relation to the present findings.