Showing papers by "Sapienza University of Rome published in 1973"

Existence Theorems in Elasticity

Abstract: The subject to be developed in this article covers a very large field of existence theory for linear and nonlinear partial differential equations. Indeed, problems of static elasticity, of the propagation of waves in elastic media, and of the thermodynamics of continua require existence theorems for elliptic, hyperbolic and parabolic equations both linear and nonlinear. Even if one restricts oneself to linear elasticity, there are several kinds of partial differential equations to be considered. In static problems we encounter second order systems, either with constant or with variable coefficients (homogeneous and non-homogeneous bodies), scalar second order equations (for instance either in the St. Venant torsion problems or in the membrane theory), fourth order equations (equilibrium of thin plates), eighth order equations (equilibrium of shells). Each case must be considered with several kinds of boundary conditions, corresponding to different physical situations. On the other hand, to every problem of static elasticity corresponds a dynamical one, connected with the study of vibrations in the elastic system under consideration. Moreover, problems of thermodynamics require the study of certain diffusion problems of parabolic type. In addition to that, the study of materials with memory requires existence theorems for certain integro-differential equations, first considered by Volterra.

Boundary Value Problems of Elasticity with Unilateral Constraints

Abstract: In the preceding article “Existence Theorems in Elasticity”, which henceforth will be cited as E.T.E.1, I have treated boundary value problems of Elasticity in the case when the side conditions to be associated with the differential equations of equilibrium correspond to bilateral constraints imposed upon the elastic body. In this article I will treat the analytical problems which arise when unilateral constraints are imposed.

Human lymphocyte subpopulations: classification according to surface markers and-or functional characteristics.

Abstract: Lymphocytes of birds and mammals can be subdivided into two major groups according to origin and function. If classified according to dependence or origin they are called thymus-dependent or T lymphocytes and bursa-derived or B lymphocytes (Raff 1973). Whereas in animal model systems the functional role of these cells have been assessed under varying experimental conditions, analogies have been provided for by the experiment of nature in human beings suffering from immunodeficiency disorders (Gatti 1972, Cooper e al. 1973). Such comparisons have made it possible to state quite emphatically that the human T and B lymphocyte populations exist with similar functional characteristics as in the other mammals. Whereas especially in the mouse, progress into the functional characteristics of the subpopulations of lymphocytes have been made largely on the basis of development of surface markers allowing actual physical separation of the various groups of cells, less is known about such ptossibilities in the human system. It is the purpose of the present article to present some of the surface markers we have used in our analysis of human lymphocytes under varying clinical and experimental conditions. The present article has no ambition to make a complete review of this field but will merely cover our own results and present views on human lymphocytes, their functional characteristics and distinguishing markers in healthy or diseased human beings. The reader is referred to the other articles in this issue to receive a more complete and maybe more objective picture.

Hemoglobins from trout - structural and functional properties

Abstract: The diversity of the structural and functional properties of the various components of trout blood may be taken as a type case of molecular adaptation to physiological requirements. Studies on this system yield, in addition, information which appears relevant to the interpretation of the behavior of mammalian hemoglobins.

The use of preparations of urinary bladder smooth muscle for bioassay of and discrimination between polypeptides.

Abstract: Eleven polypeptides, two prostaglandins and three amines were assayed, in parallel, by measurement of their spasmogenic effect on the isolated urinary bladder of eight animal species, the in situ bladder of three species and the isolated ureter of three species. Several of the smooth muscle preparations examined proved to be sensitive and suitable test-objects for the quantitative bioassay of different peptides. At the same time they appeared to be useful for discriminating not only between peptides belonging to different groups, but also between members of the same peptide family. It is tentatively suggested that biogenic peptides may interfere in the physiological control of motility and tone of the urinary tract smooth muscle.

Food avoidances of pregnant women in Tamilnad

Abstract: Over a period of six months, 1200 Tamilnad women were interviewed about food avoidances during pregnancy. Practically all types of food were avoided but the most important were those of fruits and grains. The main reason for abstaining from certain foods during pregnancy was fear of abortion caused by heating the body or by inducing uterine hemorrhage. The latter property was most frequently ascribed to foods like pawpaw and sesame grains which were supposed to have a positive as well as a negative stimulating effect on the female organism. High protein foods may be avoided because they were thought to cause exaggerated growth of the baby which would be undesirable for an easy delivery. The author attempted to find psychological explanations for the major avoidances.

Plasma testosterone and androstenedione after orchiectomy in prostatic adenocarcinoma.

Abstract: Plasma testosterone produced mainly by the testes is considered a major factor in the stimulation of the growth of tumor tissue in carcinoma of the prostate. Therefore orchiectomy is considered the treatment of choice. However after a period of time tumor growth recommences but can be delayed by the administration of estrogens or compounds with antiandrogenic activity. Study was made of 27 patients with prostatic adenocarcinoma aged 37 to 74 years who had orchiectomy to determine whether circulating androgens of either adrenal or extraglandular origin might be present. They were not given hormone therapy. The assay 17-ketosteroids (17KS) and 17-hydroxycorticosteroids (17-OHCS) in 24-hour urine specimens and the assay of testosterone and androstenedione in blood were done on samples collected before and 10 30 and 60 days after operation. Details of technique are given. Before orchiectomy test results were within normal limits. In 17 patients marked reduction of plasma testosterone was found; these men benefitted from the operation. In 10 patients plasma testosterone and androstenedione remained 5 times higher than in the others and the operation did not improve symptoms. The adrenal cortex is considered the source of the product of androgens in these patients. Suppression of adrenal function with dexamethasone was done. A drop in testosterone and androstenedione levels was observed. In orchiectomized patients the adrenal cortex appears to be the source of testosterone and other weaker androgens. The prostatic adenocarcinoma tissue may be capable of transforming weak endrogens into more active compounds.

Surface Markers on Lymphocytes of Patients with Infectious Diseases

Abstract: Peripheral blood lymphocytes from normal subjects and patients with viral and bacterial infectious diseases were examined for the presence of three surface markers: (i) surface immunoglobulins, (ii) receptor for C3 complement component (EAC test), and (iii) spontaneous binding of sheep red blood cells (E rosette formation). The first two markers are used to detect bone marrow-derived lymphocytes (B cells); the E rosette formation is dependent on thymus-derived lymphocytes (T cells). We demonstrated these assumptions, as defined by others, by the fractionation of lymphocytes on bead columns coated with immunoglobulin plus anti-immunoglobulin. The peripheral blood lymphocytes of normal individuals consisted of 52% T cells, 23% B cells with EAC receptor, and 21% B cells with membrane immunoglobulin. There was no significant difference in these values from those obtained in viral or bacterial diseases. Only a few cases of infectious mononucleosis had an increase in T cells. These results give us a partial picture of the T- and B-cell frequency in normal subjects and in patients with infectious diseases.

A Generalization of the Phillips Curve for a Developing Country

Abstract: The aim of the present study is to propose and test a generalization of the Phillips curve for a developing country which starts out with a substantial volume of structural unemployment and gradually works it down in the development process. The central conclusion of the paper is that, while an expansion of effective demand and employment beyond the previous crest gives rise in the short run to inflationary pressures on the labour market, it also induces an on-the-job training effect for the labour force previously excluded from the productive process. The resulting permanent improvement in the skill and competitiveness of the labour force thereafter reduces the inflationary pressure associated with any given level of employment. Accordingly, in a developing country, the Phillips curve can be pictured as a frontier which in the process of development tends to the left and downwards. This inference will be shown to be supported by empirical data drawn from the experience of the Italian post-war period. In this analysis we focus on the industrial sector on the ground that in a developing country the latter tends to set the pace for the entire wage structure. The pioneering studies of Stigler [14] and [15], Alchian [1], Holt and David [4], and Phelps [11] have recently laid the foundations for a new micro-economic theory of employment and inflation and stimulated a growing literature on the theoretical basis of the Phillips curve.3 These studies, however, have the common characteristic of dealing with a labour market close to full employment. Thus, like the previous work on the Phillips curve, they are directly relevant only to already developed countries. We propose to show, however, that the new approach and, in particular, the formulation of C. C. Holt can be readily generalized to analyze the labour market of a developing economy. Part I briefly reviews Holt's analysis. Part II extends its implications to a developing system. In Part III, the central hypothesis of the paper is tested. Some implications are

Pathogenicity of the Y form as compared to M form in experimentally induced Candida albicans infections

Abstract: Experimental pathogenicity of the Y form and the M form ofC. albicans separated with a high degree of purity has been evaluated. Experiments are described in which the two morphological forms ofC. albicans were separately inoculated intradermally, intraperitoneally and intravenously in mice and rabbits. In suitable conditions, higher pathogenicity was significantly provoked by the Y form ofC. albicans.

Shiver-Audiometry in the Conditioned Guinea-Pig (Simplified Anderson-Wedenberg Test)

Abstract: The hearing test of Anderson and Wedenberg has been simplified and called Shiver-audiometry, in reference to its characteristics. Easy to conduct and economical, it has proved highly versatile, as the experiments carried out on albino and pigmented guinea-pigs have demonstrated. It has actually made it possible to identify really normally-hearing animals, and to establish that the albino guinea-pig has, in the experimental conditions adopted, a greater hearing capacity than the pigmented one; moreover it has revealed that the albino guinea-pig has greater cochlear sensitivity to acoustic hyper stimulation. Shiver-audiometry has proved important in the dynamic study of hearing in experiments of short and medium duration, in that it indicates the location and degree of the lesions, as well as their evolution. For these reasons, it has been most useful in directing morphological research towards the more damaged cochlear sectors, for instance during intoxication (kanamycin) or the aftermath of an acoustic tr...

Food avoidances at puberty and menstruation in Tamilnad: An anthropological study

Abstract: One thousand and two hundred women of 54 castes and 55 tribal women in Tamilnad (South India) were interviewed during a period of six months on food avoidances during puberty and subsequent menstruation Avoidances referred to different types of food, but the most significant were those of animal origin This practice could be explained by the concept of purity and pollution Even non‐vegetarians held animal foods to be impure and, as women during menstruation are considered impure also, they should abstain from consuming them to prevent the pollution increasing Eggs, though coming under the impure category, were nevertheless eaten at puberty, because of their reputed “strengthening” effect on the girl's body for future pregnancies Avoidances during ordinary menstruation were much rarer than at puberty indicating a decreased concern with habituation

The action of bombesin on the kidney of the anaesthetized dog

Abstract: Summary 1 In the anaesthetized dog bombesin had a potent antidiuretic effect, and sometimes arrested urine flow completely. Threshold doses, by i.v. infusion, were of the order of 0·5–1 (ng/kg)/minute. Antidiuresis was the result of a reduction in glomerular filtration rate provoked by a fall in intraglomerular hydrostatic pressure. This, in its turn, was due to afferent vasoconstriction. 2 The spasmogenic effect of bombesin on the smooth muscle of the afferent arterioles was directly demonstrated by the radioactive microspheres technique and indirectly by the 85Kr washout method and by [3H]-p-aminohippurate clearance. The vascular compartment most sensitive to bombesin was that of the outer cortical zone, especially in its external half. 3 Filtration fraction decreased under the influence of bombesin, indicating that the effect of the polypeptide on postglomerular arterioles was, if present, only of minor importance. 4 At high infusion rates (above 6 (ng/kg)/min), bombesin produced a decrease in [3H]-p-aminohippurate extraction. The effect of the polypeptide on fractional distal delivery of sodium varied with the dose: at moderate infusion rates it decreased, at high infusion rates it increased. The total glucose appearing in urine following a glucose load was sharply reduced by bombesin. However, the glomerular filtration rate/maximum tubular glucose transport ratio did not show any appreciable change. 5 Afferent vasoconstriction produced by bombesin was accompanied by an intense activation of the renin-angiotensin system, as shown by a conspicuous increase in renin secretion, followed by increases in renin activity and angiotensin II concentration in arterial blood. When bombesin was infused into one renal artery only the infused kidney showed afferent vasoconstriction and increased renin secretion. The time-course of renin secretion produced by bombesin depended upon the rate of infusion of the polypeptide. At low rates an increased renin secretion was observed throughout the infusion period, at high rates two peaks of renin secretion could be seen, one at the beginning of the infusion, the other soon after the infusion had finished. 6 The mechanism of action of bombesin is discussed and the interest of the polypeptide as a possible hormonal regulator of the circulation and function of the kidney is pointed out.

Hydration of Beta Dicalcium Silicate Alone and in the Presence of CaCl2 or C2H5OH

Abstract: Beta C2S was hydrated at room temperature with and without added CaCl2 or C2H5OH by methods previously studied for the hydration of C3S, i.e. paste, bottle, and ball-mill hydration. The amount of reacted β-C2S, the Ca(OH)2 concentration in the liquid phase, the CaO/SiO2 molar ratio, and the specific surface area of the hydrate were investigated. A topochemical reaction occurs between water and β-C2S, resulting in the appearance of solid Ca(OH)2 and a hydrated silicate with a CaO/SiO2 molar ratio of ≃1. As the liquid phase becomes richer in Ca(OH)2, the first hydrate transforms to one with a higher CaO/SiO2 ratio. Addition of CaCl2 increases the reaction rate and the surface area of the hydrate but to a much lesser extent than in the hydration of C3S, whereas C2H6OH strongly depresses the hydration rate of β-C2S, as observed for C3S hydration.

On Allosteric Models

Abstract: The basic idea of the allosteric interpretation of macromolecular behaviour is that the various ligand binding sites of the macromolecule interact not directly but indirectly as a result of ligand linked conformational equilibria, but within this general framework many different models are possible. It can be shown that the two models most commonly employed, namely the MWC model and the induced-fit model of Koshland and Nemethy, are in reality both special cases of a more general parent model. The MWC model is always cooperative. In contrast the induced-fit model may be either cooperative or anticooperative, depending on the choice of constants. An example of allosteric behaviour which illustrates these ideas is provided by the components of trout hemoglobin.

Action of caerulein and caerulein-like peptides on "short-circuit current" and acid secretion in the isolated gastric mucosa of amphibians.

Abstract: Caerulein produced an increase of the “short-circuit current” in the isolated gastric mucosa of Rana esculenta and Bufo viridis. Threshold concentrations were of the order of 10−10 M and 3×10−11 M, respectively. A dose-response relationship was observed for concentrations of the polypeptide up to 10 to 20 times the threshold. At the same time, the polypeptide also caused an increase in the secretion of hydrochloric acid by the isolated mucosa, as measured by a direct titrimetric method. The effects of caerulein were atropine-resistant, and hence not mediated through a cholinergic mechanism.