Showing papers by "University of Perugia published in 1985"

Characterization of the soluble alkaline phosphatase from hepatopancreas of Squilla mantis L.

Abstract: 1. 1. A soluble alkaline phosphatase (AP) present in the hepatopancreas of Squilla mantis was extracted. 2. 2. The enzyme was purified by acetone fractionation and then by DEAE-cellulose and Sephadex G-200 chromatography; a single AP form was obtained, which was characterized by studying molecular and catalytic properties. 3. 3. Kinetic studies were carried out using phosphoesters as inhibitors; all these substances led to competitive inhibition. The enzyme shows a higher affinity for ADP and ATP; glucose phosphoesters are weak inhibitors. 4. 4. Possible roles of the studied AP in vivo are discussed.

Role of hepatic autoregulation in defense against hypoglycemia in humans.

Abstract: To assess the role of hepatic autoregulation in defense against hypoglycemia, we compared the effects of complete blockade of glucose counterregulation with those of blockade of only neurohumoral counterregulation during moderate (approximately 50 mg/dl) and severe (approximately 30 mg/dl) hypoglycemia induced by physiologic hyperinsulinemia during subcutaneous infusion of insulin in normal volunteers. Compared with observations in control experiments, neurohumoral counterregulatory blockade (somatostatin, propranolol, phentolamine, and metyrapone), during which identical moderate hypoglycemia was achieved using the glucose clamp technique, resulted in suppressed glucose production (0.62 +/- 0.08 vs. 1.56 +/- 0.07 mg/kg per min at 12 h, P less than 0.01) and augmented glucose utilization (2.17 +/- 0.18 vs. 1.57 +/- 0.07 mg/kg per min at 12 h, P less than 0.01). Complete blockade of counterregulation (neurohumoral blockade plus prevention of hypoglycemia) did not further enhance the suppressive effects of insulin on glucose production. However, when severe hypoglycemia was induced during neurohumoral counterregulatory blockade, glucose production was nearly two times greater (1.05 +/- 0.05 mg/kg per min at 9 h) than that observed during complete counterregulatory blockade (0.58 +/- 0.08 mg/kg per min at 9 h, P less than 0.01) and that observed during mere neurohumoral blockade with moderate hypoglycemia (0.59 +/- 0.06 mg/kg per min at 9 h, P less than 0.01). These results demonstrate that glucose counterregulation involves both neurohumoral and hepatic autoregulatory components: neurohumoral factors, which require only moderate hypoglycemia for their activation, augment glucose production and reduce glucose utilization; hepatic autoregulation requires severe hypoglycemia for its activation and may thus serve as an emergency system to protect the brain when other counterregulatory factors fail to prevent threatening hypoglycemia.

Modulation of natural killer activity by thymosin alpha 1 and interferon.

Abstract: A single injection of alpha beta-interferon (alpha beta-IFN) (30000 units/mouse), a major biological modifier of natural killer (NK) cytolytic activity, strongly stimulated NK activity in normal mice, as expected, while the same treatment did not statistically alter the NK response in cyclophosphamide (CY)-suppressed animals. We investigated the possibility of thymosin alpha 1 cooperating with alpha beta-IFN in boosting NK activity in CY-suppressed animals. The results show that treatment with thymosin alpha 1 (200 micrograms/kg) for 4 days, followed by a single injection of alpha beta-IFN 24 h before testing, strongly restored NK activity in CY-suppressed mice. Thymosin alpha 1 was, moreover, able to accelerate the recovery rate of NK activity in bone marrow reconstituted murine chimeras. Taken together the data support the concept that the synergic effect between thymosin alpha 1 and alpha beta-IFN could be the result of effects on differentiation of the NK lineage at different levels.

A new bond-order functional form for triatomic molecules

Abstract: A generalization to the triatomic systems of a Bond Order approach developed in the preceding paper for the diatomic molecules is discussed. The new global fitting procedure is first tested against other methods for the H3 molecule and then applied to the BeHF system.

Diatomic potential functions for triatomic scattering

Abstract: The use of a bond-order-like functional form within the framework of a procedure designed for fitting both experimental and ab initio diatomic data is discussed. The advantage of using such a functional form for describing the two body component of a polyatomic interaction is illustrated. Its accuracy is tested by fitting spectroscopic and scattering information relative to several diatomic systems.

Production, purification and partial characterization of an endo-polygalacturonase from Cryptococcus albidus var. albidus.

Abstract: Cryptococcus albidus var.albidus produced an extracellular endo-polygalacturonase (poly (1,4-α-d-galacturonide) glycanohydrolase EC 3.2.1.15) when grown in a synthetic medium containing one of a variety of pectic substances or galacturonic acid. The highest level of enzyme activity (15.5 VU-ml−1) was obtained after 72 h of growth on 1.0% low-methoxyl pectin. The enzyme, purified by gel filtration (Sephadex G-100) after repeated ammonium sulphate precipitation and dialysis, showed only one band by polyacrylamide gel electrophoresis and had the following properties: mol wt (MWr) 41000 dal; isoelectric point (pl) = 8.10 ± 0.10; optimum temperature and pH for activity around 37°C and pH 3.75, respectively; pH stability in the pH range 4.0 to 8.0; complete heat inactivation after 10 min at 55°C; Km and Vmax values 5.7· 10−1 mg·ml−1 and 5.1 · 10−1 mmoles·min−1, respectively.

Antagonistic activity of fungi isolated from sclerotia of Sclerotinia sclerotiorum

Abstract: Fungi isolated from soils in central Italy by a baiting technique with sclerotia of Sclerotinia sclerotiorum were evaluated for their antagonism in vitro to this fungus using dual cultures and tests with sclerotia. Trichoderma spp., Coniothyrium minitans and species of Fusarium and Penicillium all showed strong antagonistic activity. Morphological alterations were observed in the mycelium of S. sclerotiorum. Trichoderma spp. and Gliocladium catenulatum killed a very high percentage (96–100%) of the sclerotia.

Platelet activation in psoriasis.

Abstract: Recent epidemiological studies have suggested that psoriasis represents a risk factor for thrombotic vascular diseases In order to evaluate the possible role of hemostatic changes in the development of thrombotic episodes in psoriasis, some parameters of the hemostatic "balance" were investigated in 22 male psoriatic patients and compared to those of 22 male control subjects Incidence of known risk factors for vascular diseases (diabetes, hypertension, smoking, dyslipidemia) was comparable in the two study groups There were no statistically significant differences in platelet count, circulating platelet aggregates, platelet production of malondialdehyde (MDA), total plasma antithrombin and fibrinolytic activities In patients with psoriasis the incidence of spontaneous platelet hyperaggregability and plasma levels of beta-thromboglobulin were significantly higher than in control subjects Platelet regeneration time, measured as MDA recovery after aspirin ingestion, was significantly shorter in psoriatic patients These data suggest that an in vivo platelet activation occurs in patients with psoriasis and could contribute to the development of thrombotic complications The release of mitogenic and inflammatory substances by activated platelets may play a role in the histogenesis of psoriatic lesions

Immunoadjuvant activity of amphotericin B as displayed in mice infected with Candida albicans.

Abstract: Mice receiving a single intraperitoneal injection of amphotericin B showed increased resistance to subsequent challenge with either Candida albicans or Staphylococcus aureus. This enhancement of resistance was obvious in terms of both survival criteria and clearance of the intravenously injected organism from different organs. The protective effect of amphotericin B was conditioned by dose, time of drug administration, and size of yeast or bacterial inoculum and was reversed by cyclophosphamide. Effector cells from mice treated with amphotericin B displayed enhanced fungicidal activity in vitro as measured in a short-term 51Cr release assay. Macrophages from intact animals exposed in vitro to amphotericin B also acquired strong candidacidal reactivity.

Phospholipids in plant and animal chromatin.

Abstract: Isolated hepatic nuclei and hepatic chromatin have been analysed for their DNA, RNA, protein and phospholipid content. The protein/DNA ratio is 3 for nuclei and 1.95 for chromatin extracted from Triton X-100 treated nuclei. The phospholipids, (2.36 +/- 0.91 (S.D.) per cent of the total nuclear material), are lost during the chromatin preparation mainly during the Triton X-100 washings of the nuclei. Nevertheless, 10 per cent of the total nuclear phospholipids remain bound to the chromatin. The comparative analysis of both nuclei and chromatin shows a difference in phospholipids and fatty acid composition. Thus, the chromatin-associated phospholipid cannot be attributed simply to contaminating nuclear membrane. This is supported by the autoradiographic study of semi-thin sections of interphase nuclei from root apices of Vicia faba in which [3H] ethanolamine is clearly localized in the chromatin and nucleolar regions of the nuclei.

In-vitro killing of Candida species by murine immunoeffectors and its relationship to the experimental pathogenicity

Abstract: Killing of yeast cells of several species of Candida by murine phagocytic cells was assessed in vitro by a radiolabel release microassay and measurement of colony forming units. The most effective candidacidal phagocytes, i.e. polymorphonuclear and bone marrow cells, were able to kill equally well cells of any species or isolate tested, given sufficient time (4 h) and an appropriate effector: target ratio. However, C. guilliermondii, C. krusei and C. parapsilosis were killed by polymorphonuclear and bone marrow cells much more promptly (1 h) and at a significantly lower effector:target ratio than C. albicans, C. tropicalis and C. viswanathii. Moreover, there were immune effectors such as peritoneal resident macrophages and, mostly, spleen cells which were practically ineffective against C. albicans and C. tropicalis but showed significant activity against C. guilliermondii, C. krusei and C. parapsilosis, even in mice immuno-depressed with cyclophosphamide. Three isolates of C. albicans, differing in the capacity to form germ tubes, also differed in mouse virulence: the germ-tube forming isolate was the most virulent. However, they showed an identical pattern of susceptibility to killing by mouse immunoeffectors, suggesting that virulence is probably not due to the resistance of hyphal cell to phagocytosis.

Mutagenicity assessment of different drinking water supplies before and after treatments

Abstract: In this study, three qualitatively different raw water supplies together with their correspondent chlorinated drinking waters were investigated for their mutagenic properties using the Salmonella/microsome assay. A drinking water supply distributed through two different types of pipelines was chosen in order to study the effect of the distribution systems on water mutagenicity. A sequential liquid-liquid extraction at three different pHs and an in situ XAD-2 adsorption technique were used to prepare extracts and adsorbates from both untreated and treated water samples to compare mutagen recovery by these widely used methods and with a view to selecting a routine screening technique for evaluating the effect of treatments on drinking water mutagenicity.

Contribution to the differentiation of peripheral versus central tinnitus via auditory brain stem response evaluation.

Abstract: Auditory brain stem response (ABR) parameters were evaluated in 54 subjects with unilateral idiopathic subjective tinnitus in order to verify the possibility of detecting its site of origin. All the subjects had normal hearing or a symmetrical bilateral sensorineural hearing loss. All the cases in whom middle or inner ear disease had been diagnosed, were excluded. Subjects, classified on the basis of their mean auditory threshold and masking curves according to Feldmann, underwent a residual inhibition (RI) test and ipsilateral narrow-band noise masking before a second ABR test was performed. Patients with positive RI made up the A+ group, while those with negative RI made up the A-group. The main characteristics observed were an increase of the mean latency values of wave I in the tinnitus ear in the A+ group while, after masking, the values of the affected and unaffected ears almost overlapped. An increase in the latency values of wave V, unaffected by the masking procedure, could be observed in A- pati...

Inclusive particle production in the transverse momentum range between 0.25 and 40 GeV/c at the CERN $$Sp\bar pS$$ collider

Abstract: Inclusive particle production cross-sections have been measured at the $$Sp\bar pS$$ collider using the UA2 detector in various ranges of transverse momentum (P T ) and pseudo-rapidity (η). Cross-section measurements are presented forπ 0 production (P T ≦15 GeV/c, |η|≦0.85 andP T ≦40 GeV/c, 1.0≦|η|≦1.8), for η meson production (3≦P T ≦6 GeV/c, |η|≦0.85) and for charged particle production (P T ≦10 GeV/c, 1.0≦|η|≦1.8). Results are compared with the predictions of QCD calculations.

Identification of muscarinic receptor subtype mediating colonic response to eating.

Abstract: The colonic motor response to eating requires cholinergic transmission. Recent studies have identified two subclasses of muscarinic receptor, the M1 and the M2 subtype. The aim of this study was to evaluate the muscarinic receptor subtype responsible for mediating the gastrocolonic response. Spike potential (SP) activity and intraluminal pressure were recorded, during fasting and after eating a 1000-kcal mixed meal, from the distal colon of 10 healthy volunteers. In each subject three paired studies were carried out: either atropine (a nonselective antimuscarinic, 1 mg), pirenzepine (a selective M1 antimuscarinic, 10 mg), or saline were infused intravenously before eating, using a double-blind crossover design. The meal significantly increased colonic spike potential activity (17.6±3.9, SP/30 min) above fasting values (2.7±0.6,P<0.01) in the control study. There was no postprandial increase in spike potential activity (3.3±0.9, SP/30 min) after atropine. The meal also significantly increased spike potential activity (15.4±3.3 SP/30 min,P<0.01) above fasting levels and equal to that of the controls, in the pirenzepine study. These data suggest that the colonic motor response to eating is mediated through the M2 but not the M1 subtype of muscarinic receptors.