Showing papers by "University of Bologna published in 1982"

Polar wandering and the forced responses of a rotating, multilayered, viscoelastic planet

Abstract: Changes in the earth's rotation produced by the waxing and waning of large mobile ice sheets can be used to infer the viscosity of the mantle from a comparison with the recent secular polar drift as revealed in the International Latitude Service data and also in the estimates of the nontidal acceleration of the length of the day. We have developed by using an analytical approach a physical model of a rotating earth consisting of an elastic lithosphere, a viscoelastic mantle, and an inviscid core. Forcings from the two major ice sheets, Laurentide and Fennoscandia, have been considered. Sensitivity analysis of the parameters governing the external forcings, such as the length and the time of termination of the deglaciation phase, show in general that there exist two families of mean mantle viscosities, 0(1022 P) and 0(1023 P), which can match the data satisfactorily. However, we find it an improvement to incorporate some amount of shrinkage from the Antarctic ice sheet, obtaining simultaneously a better fit with the two rotational data sets to the lower viscosity solutions. Hence forcings from the southern hemisphere may be able to remove the ambiguity associated with the extraction of mantle viscosity from rotational data. We have also solved the initial value problem of the components of instantaneous angular velocity by means of the Laplace transform for applied loads characterizing the continental ice sheets, which since the mid-Pliocene have periodically expanded and contracted over the northern hemisphere. In consequence of this continual forcing, polar wander of around 5–10 degrees can take place for a mean mantle viscosity 0 (1022 P). Recent reanalysis of paleomagnetic data in conjunction with hot spot tracks have revealed that several degrees of true polar wander could have occurred in the last 5 m.y. These calculations thus provide a physical explanation for the observed movement of the rotation axis. Membrane stresses of 0 (10) bars can develop from this secular polar motion.

Features of the photochemically active state surfaces of azobenzene

Abstract: To discuss the main features of the potential energy curves of azobenzene along the two possible isomerization paths ab initio and cofiguration-interaction (CI) computations have been performed for the cis and trans isomers and for the intermediate geometries along the rotational and the inversion isomerization paths. From the expression of the excited states, we propose a correlation diagram and potential energy curves for the ground and lowest excited states. These curves, integrated with the available experimental data, provide a basis for interpreting the photochemical and photophysical properties of azobenzene.

No classical type IIB fibres in dog skeletal muscle.

Abstract: To analyse the fibre type composition of adult dog skeletal muscle, enzyme histochemistry, immunohistochemistry for type I, IIA and IIB myosins, and peptide mapping of myosin heavy chains isolated from typed single fibres were combined. Subdivision of type II fibres into two main classes according to the activity of the m-ATPase after acidic and alkaline preincubation proved to be rather difficult and was only consistently achieved after a very careful adjustment of the systems used. One of these sub-classes of type II fibres stained more strongly for m-ATPase activity after acidic and alkaline preincubation, was oxidative-glycolytic and showed a strong reaction with an anti-type IIA myosin. The other one, however, although unreactive with anti-IIA myosin, was also oxidative-glycolytic, and only showed a faint reaction with an anti-type IIB myosin. Peptide mapping of the myosin heavy chains of typed single fibres revealed two populations of heavy chains among the type II fibre group. Thus, in dog muscle, we are confronted with the presence of two main classes of type II fibres, both oxidative-glycolytic, but differing in the structure of their myosin heavy chains. In contrast to some reports in the literature, no classical type IIB fibres could be detected.

'Carcinoid' tumours of the breast: the morphological spectrum of argyrophil carcinomas.

Abstract: Fourteen 'carcinoid' tumours of the breast are described. They are separable into five with and nine without intracellular mucin. All the tumours are argyrophil, but none is argentaffin. Four tumours studied ultrastructurally contain dense-core granules. Argyrophil carcinomas represent the endocrine analogues of ductal carcinoma in situ, of invasive ductal carcinoma and probably of lobular carcinoma also. Current views vary between the one that the so-called carcinoid is a rare and totally distinct entity to the view, at the other extreme, that it is a very common variant of conventional breast cancer. On the basis of our findings, an intermediate view is justified: argyrophil carcinomas constitute about 5% of breast carcinomas and some varieties at least have non-argyrophil analogues. Factors influencing the prognosis in individual cases are discussed. Argyrophil carcinomas of the breast form a tumour spectrum with a wide range of morphological and histochemical appearances and a variable prognosis.

The use of β-galactosidase as a tracer in immunocytochemistry

Abstract: A new immunocytochemical method using β-galactosidase as a tracer is described. The positive staining appears blue on an unstained background. The present method has the high sensitivity and specificity of the immunoperoxidase method and appears to be a practical alternative. The substrate has no carcinogenic activity. Staining is permanent and the sections can be dehydrated and mounted in synthetic media. Enzyme and substrate solutions are stable for several months.

Isolation of putative benzodiazepine receptors from rat brain membranes by affinity chromatography.

Abstract: The benzodiazepine receptor from rat brain was solubilised and purified 5200-fold by affinity chromatography. The affinity column contained an immobilized benzodiazepine (delorazepam) and biospecific elution with 6 mm-chlorazepate was achieved. The purified receptor is apparently homogeneous in SDS-polyacrylamide gel electrophoresis. The native protein had a molecular weight of 240,000, and the subunit one of 60,000. The dissociation constant (KD) is 8 nm for [3H]diazepam. A correlation exists between the value of affinity obtained for benzodiazepine derivatives and their known pharmacological effectiveness.

The treatment of localized Ewing's sarcoma: the experience at the Istituto Ortopedico Rizzoli in 163 cases treated with and without adjuvant chemotherapy.

Abstract: Eighty consecutive patients with localized Ewing's tumor treated with adjuvant chemotherapy for two years plus local tumor control were retrospectively reviewed. Adjuvant chemotherapy protocol was constant for all patients, but local treatment consisted of amputation, resection (complete or incomplete) plus radiotherapy, or radiotherapy alone. The follow-up ranged from 21–101 months (x = 50 months). The mortality rate and incidence of metastasis were significantly lower than in a comparable group of 83 patients previously treated by radiotherapy, or surgery plus radiotherapy but without chemotherapy. The percentage of local recurrence was not significantly different between the two groups. Of the patients treated with adjuvant chemotherapy, the percentage of local recurrence and metastases was much lower when the primary lesion was located in the extremeties and when this lesion was treated by conservative surgery followed by irradiation. This was also true when the resection was not complete. Little discrepancy in functional results was observed using either resection plus radiotherapy or radiotherapy alonea. The above data suggest that in treating Ewing's sarcoma, conservative surgery, even incomplete, can play an important role when associated with radiotherapy and adjuvant chemotherapy.

Application of fracture mechanics to concrete structures

Abstract: Material properties (heterogeneity and non-linearity) and disturbing phenomena (slow crack growth and microcracking) cause several research-workers to be pessimistic about the applicability of fracture mechanics to concrete structures. A critical review of the preceding works dealing with concrete fracture is presented. During the 1960’s and 1970’s it became more and more evident that notch sensitivity is not a material property but only a phenomenon dependent on the specimen and crack sizes, and that the degree of heterogeneity is only a matter of scale. A true fracture collapse can occur only with very large structures. On the other hand a real ultimate strength collapse can occur only with very small fracture specimens. Usually, with the sizes of the structures built by man and the lengths of the natural cracks, the two collapses are interacting.

Bile acid malabsorption and bile acid diarrhea in intestinal resection.

Abstract: Bile acid fecal excretion and dihydroxy bile acid concentration in the fecal water of patients with large (N = 6) and small (N = 8) ileal resection, colectomy (N = 5), and healthy controls (N = 10) have been studied in order to evaluate the degree of bile acid malabsorption and the occurrence of bile acid diarrhea in intestinal resections of different extent. Bile acid malabsorption was severe in large ileal resections, mild in small ones, and slight in colectomy. The fecal pH seems to be a limiting factor in the occurrence of a bile acid diarrhea, playing a critical role in determining the dihydroxy bile acid solubility in the fecal water. These results seem to suggest that the bile acids may induce water secretion in the colon not only in small but also in large ileal resections.

The morphological relationship in electron microscopy between nor-silver proteins and intranucleolar chromatin

Abstract: The relative distribution of NOR proteins and chromatin fibers in the nucleoli was visualized in human cell line. The chromatin was revealed by a Feulgen-like procedure using osmium-ammine as DNA tracer. This selective staining was combined with NOR-silver staining. We provide morphological evidence for constant overlapping of the silver deposit sites with dispersed intranucleolar chromatin fibers. Silver stained proteins were sometimes observed in contact with the chromatin fibers, suggesting that at least some of the Ag-NOR proteins might be closely connected with the dispersed nucleolar DNA.

Components of Royal Jelly II. The Lipid Fraction, Hydrocarbons and Sterols

Abstract: SummaryQuantitative differences were found in the chemical composition of royal jelly samples collected in spring and summer by the same producer. The main difference was in the free fatty acids, which showed a marked increase in 10-hydroxydecanoic acid in summer. The sterol and hydrocarbon fractions were also investigated. The most significant sterols were identified by gas chromatography—mass spectrometry. The hydrocarbon components, identified by their retention times, were a homologous series of straight-chain compounds, from C16 to C33, with even and odd numbers of carbon atoms. Considerable amounts of some hydrocarbons were found. Of the sterols identified, the most abundant was 24-methylene cholesterol; stigmasterol, β-sitosterol, Δ5-avenasterol, Δ7-avenasterol and cholesterol were also present.

Effect of ribosome-inactivating proteins on virus-infected cells. Inhibition of virus multiplication and of protein synthesis.

Abstract: HEp-2 cells were infected with herpes simplex virus-1 (HSV-1) or with polio-virus I in the presence of plant proteins which inactivate ribosomes in cell-free systems, while exerting scarce effect on whole cells. Ribosome-inactivating proteins used were gelonin, from seeds of Gelonium multiflorum, an inhibitor from the seeds of Momordica charantia, dianthin 32, from the leaves of Dianthus caryophyllus (carnation), and PAP-S, from the seeds of Phytolacca americana (pokeweed). All proteins tested had the following effects: 1. They reduced viral yield; 2. They decreased HSV-1 plaque-forming efficiency; 3. They inhibited protein synthesis more in infected than in uninfected cells. These results strongly suggest that ribosome-inactivating proteins impair viral replication by inhibiting protein synthesis in virus-infected cells, in which presumably they enter more easily than in uninfected cells.

Self-bounded controlled invariant subspaces: A straightforward approach to constrained controllability

Abstract: A lattice-type structure is shown to exist in a particular subset of the set of all (A, ℱ)-controlled invariants contained in\(\mathcal{N}\) and containing\(\mathcal{N}\), whereA denotes a linear map inR n ; ℱ,\(\mathcal{N}\) are arbitrary subspaces ofR n ; andD is an arbitrary subspace ofJ, the maximum (A, ℱ)-controlled invariant contained in\(\mathcal{N}\). In linear system theory, this property can be used for a more direct theoretical and algorithmic approach to constrained controllability and disturbance rejection problems.

Myofibrillar protein catabolic rates in cirrhotic patients with and without muscle wasting.

Abstract: 1. The urinary excretion of 3-methylhistidine and creatinine was measured in 15 controls and in two groups of 15 patients with liver cirrhosis, with and without severe muscle wasting. All subjects were on a meat-free diet. The values obtained were used to calculate the fractional catabolic rate of myofibrillar protein. 2. In patients without muscle wasting 3-methylhistidine excretion was high in the presence of normal urinary creatinine. The fractional breakdown rate was significantly increased as compared with that of controls. 3. In patients with severe muscle wasting 3-methylhistidine excretion was normal and urinary creatinine was remarkably reduced. The myofibrillar catabolic rate was further increased compared with that of controls and of the other group of patients. 4. 3-Methylhistidine and creatinine excretion allow a complete evaluation of myofibrillar protein degradation, which appears to be remarkably increased in cirrhotic patients. The relevance of increased myofibrillar protein turnover in muscle wasting of subjects with advanced cirrhosis remains to be determined.

Histochemical fibre types in the lateral muscle of fishes in fresh, brackish and salt water

Abstract: The histochemical pattern of red, pink and white muscle of fish living in fresh, brackish, and salt water is reported. The muscle fibres were stained routinely during the year for lactate dehydrogenase (LDH), menadione α-glycerophosphate dehydrogenase (Mα—GPDH), succinic dehydrogenase (SDH), myosin adenosine triphosphatase (myosin ATPase), phosphorylase, lipids and glycogen. The pink and red muscles contain more glycogen and lipids and have a higher SDH activity, which is in accord with their aerobic metabolism and function in sustained swimming activity. The acid labile myosin ATPase activity characteristic of fast twitch fibres is present in the white fibres of most species, however in the white muscle of Gobius paganellus the enzyme activity is stable to both acid and alkali and, in addition, there is a scattered distribution of different fibre types in red and, especially, pink muscle. A study of seasonal variation patterns of myosin ATPase in white muscle of mugilidae over a period of two years has demonstrated, in late summer, the appearance of new small diameter fibres, with a high acid stable enzyme activity, that develop into the large diameter acid labile fibres.

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.