Showing papers by "University of Siena published in 1984"

Ideals in universal algebras

Abstract: In many familiar classes of algebraic structures kernels of congruence relations are uniquely specified by the inverse images q~-l(0)= {x [ q~(x)= 0} of a specified constant 0. On the one hand, q~-l(0) is nothing else but the 0-class of the kernel congruence of q~, on the other hand q~-~(0) can be axiomatized intrinsically, namely q l (0 ) is an ideal (in rings, Boolean algebras, or more generally in Heyt ing algebras), a normal subgroup, resp. normal subloop (in groups, resp. loops) or a filter (in Implicat ion algebras or Boolean algebras again, where 0 is replaced by the unit). In this paper we investigate common features of all the above structures by using a general notion of " ideal" , which makes sense in all universal algebras having a constant 0 and which specializes to the familar concepts of ideal, normal subgroup or filter in each of the algebras quoted above. In all universal algebras the 0-classes of congruence relations are easily seen to be ideals, but we shall require that conversely each ideal is the 0-class of a unique congruence relation. Such algebras, or ra ther classes of algebras with this proper ty will be called "classes with ideal determined congruences" or shortly ideal determined. In Part 1, after presenting the precise definitions, we shall show that the ideal determined varieties are characterized by a Mal 'cev condition, which turns out to be a combination of Fichtner 's condition for 0-regularity together with a ternary te rm r(x, y, z) which is a weakened form of Mal 'cev 's permutabil i ty term. From a result of Hagem ann it follows that ideal-determined varieties have modular congruence lattices, so the theory of commutators becomes readily available. In

Effects of prednisone and deflazacort on mineral metabolism and parathyroid hormone activity in humans

Abstract: The effects of two different glucocorticoids, prednisone and deflazacort, (an oxazoline derivative of prednisolone) on bone metabolism were analyzed in 10 patients with disorders that required glucocorticoid therapy. Significant elevations in blood immunoreactive parathyroid hormone, alkaline phosphatase and urinary calcium, phosphate, hydroxyproline and nephrogenous cyclic AMP were observed during prednisone therapy in addition to an increase in the exchangeable calcium pool as estimated by 47Ca-kinetic analyses. In contrast to these changes, deflazacort therapy induced minimal, and in some instances, no changes in these indices. In fact, in studies wherein prednisone therapy was followed by deflazacort alterations in bone metabolism, iPTH, and nephrogenous cAMP observed during prednisone were reversed. The data are consistent with the fact that the skeletal effects of prednisone therapy are mediated, at least in part, by increased parathyroid hormone activity, and that deflazacort is less potent in this regard.

Fish germinal cells. I. Comparative spermatology of seven Cyprinid species

Abstract: The spermatozoa of seven fishes belonging to Cyprinid family are examined They have no acrosome, like all Teleost fishes, a spheroidal or slightly elliptic nucleus, always eccentrically placed on the tail, two variously oriented centrioles, and a postnuclear cytoplasmic region of various size that contains some mitochondria (2 to 10) and surrounds a periaxonemal postnuclear canal The tail is of moderate length (from 36 to 60 μm) and contains a “9 + 2” axoneme: both dynein arms are present Comparative examination of the spermatozoa in the seven species shows that significant differences occur among them, even when they belong to the same genus These concern the tail length; the position of the centrioles, the proximal with respect to the central one and with respect to the nucleus; the number of mitochondria, which is in relationship to the depth of the postnuclear canal In the uniform general pattern of the ultrastructure of the Cyprinid spermatozoa, each species is characterized by a particular organization of the sperm organelles; in this respect, the two species examined by us, Leuciscus cephalus and souffia, are more closely related, even if easily recognizable one from the other From a phylogenetic point of view, the comparative spermatology of the Cyprinid fishes suggests that the mitochondrial number is a good character, which enables us to order them in a phylogenetic arrangement

The Ultrastructure of Pollen Grain Development in Lycopersicum Peruvianum

Abstract: The ultrastructure of the development of the pollen grain is described from the first meiotic division to the binucleate phase. The first meiotic division is synchronous in all the microspore mothe...

Calcium ultrastructural localization in Xenopus laevis eggs following activation by pricking or by calcium ionophore A 23187.

Abstract: In the egg of Xenopus laevis a cortical network of smooth endoplasmic reticulum (SER) surrounds and interconnects each cortical granule (CG) (Campanella and Andreuccetti, '77). This network is a possible intracellular site of calcium storage to be called into action for CG exocytosis. In our experiments, Xenopus eggs, unfertilized or activated by pricking or by calcium ionophore A 23187, have been fixed in osmium-pyroantimonate for calcium localization. Our data show that deposits can be detected only in activated egs. The calcium chelator edetate (EGTA) and x-ray microprobe analysis demonstrate that they contain calcium. Deposits are found on liposomes and on all intraovular cytomembranes, which therefore appear to be possible sites of calcium sequestration. In the case of ionophore-activated eggs, deposits are detectable independently of the presence of extracellular calcium. These data show that in Xenopus at activation an intracellular liberation of calcium occurs similar to that described in other species. Furthermore, the fact that antimony deposits are observed only after activation makes Xenopus eggs appropriate material in which to follow the temporal and spatial sequence of appearance of the deposits during the early stages of activation. Our results show that antimony deposits appear first in SER vesicles between the plasma membrane and CGs and then spread to the rest of the egg cytomembranes. These data corroborate our hypothesis that in Xenopus the cortical SER network is the first intracellular site where calcium is released at activation. The possible mechanism of calcium release and propagation along the egg cortex is discussed.

The hormonal form of vitamin D in the pathophysiology and therapy of postmenopausal osteoporosis.

Abstract: Sixty-two women with symptomatic postmenopausal osteoporosis underwent longterm treatment with 1,25-dihydroxyvitamin D3. The following results were obtained: i) a dramatic improvement of the intestinal transport of radioactive calcium, which was impaired prior to the treatment; ii) non significant increases in fasting serum calcium; iii) significant increases in the24 h urinary excretion of calcium and phosphate, resulting from the improvement of intestinal calcium absorption, and a decrease in the urinary cAMP/Cr ratio; iv) non significant changes in serum phosphate, serum alkaline phosphatase, urinary hydroxyproline; v) non significant increases in bone mineral content; vi) relief from pain and improvement of motility in all the patients; vii) no side effect was noticed. In conclusion the treatment with 1,25-dihydroxyvitamin D3 was shown to be useful in postmenopausal osteoporosis.

A Versatile Identification Method Applied to Analysis of Respiratory Mechanics

Abstract: A method for the straightforward estimation of the param eters in lumped continuous linear models of respiratory mechanics is presented in this paper. First, a discrete-time model is obtained from the samples of input-output data and then transformed into a conuous-time model.

The spermatozoon of three species of Phlebotomus (Phlebotominae) and the acrosomal evolution in nematoceran dipterans

Abstract: In this paper the spermatozoon of the dipteran Phlebotomus is described. This sperm shows a “9+9+0” flagellar pattern and an acrosomal complex, including a vesicular acrosome and a perforatorium. This last model seems to be the most primitive in Diptera, having in almost all families a simple acrosome, devoid of perforatorium. To substantiate this view, the acrosomes in Trichoceridae, Ceratopogonidae, Tipulidae, Chironomidae, Mycetophilidae and Culicidae are described. The evolutionary trends of the dipteran acrosome are compared with those of the flagellum. The 2 organelles seem to have followed different evolutionary pathways. These results suggest Psychodidae to be a well-defined family, and Phlebotominae, which is highly divergent, possibly belonging to a different family.

Infantile spasms--long term results of ACTH treatment.

Abstract: From a series of 230 subjects with infantile spasms (I.S.) observed from 1955 to 1982, 191 cases with sufficient data on follow-up and evaluation were selected. The period of follow-up in 100 subjects ranged from 3 months to 3 years and was more than 3 years in the remaining 91 patients. Disappearance of spasms and normal psychomotor development was observed in 34 of the 61 idiopathic and post-infectious cases. In 130 subjects with secondary forms normal psychomotor development was observed in only two patients; disappearance of spasms was noted in 54 and normalisation of the EEG in 13 subjects. Satisfactory long term results can be obtained with a relatively low dose of corticotropin in a considerable number of patients having idiopathic and post-infectious forms of I.S. To obtain the best results treatment should be started as soon as possible.

A comparative analysis of the evolution of the egg envelopes and the origin of the yolk

Abstract: In this paper, the evolution of egg envelope is examined from a structural point of view. The structurally simplest eggs are found in Sponges and Cnidarians where reproduction is ensured by external fertilization. In these instances, the oocyte plasma membrane is protected by only a thin glycocalyx. A more structurally complex envelope is present in triblastic Metazoa where the vitelline membrane makes its first appearance. With the emergence of internal fertilization, the egg envelope is modified as to face the constraints imposed by the terrestrial environment. However the pursuit of such defensive strategy would have made eggs practically impermeable to spermatozoa Eggs with a thick chorion are thus endowed with a proper micropyle to allow fertilization. With the acquisition of viviparity egg envelopes have undergone marked reduction. In this paper particular attention has also been paid to the relationship of the oocyte with accessory cells and to the nature and function of the reserve materi...

Treatment of Post-Menopausal Osteoporosis

Abstract: I should like to thank Professor Barbagallo-Sangiorgi for inviting me to speak again on a topic I discussed here some years ago During this time our knowledge of the pathophysiology of postmenopausal osteoporosis has advanced consistently and several therapeutic trials have been undertaken The main scheme I proposed then has not changed substantially: nevertheless at present it must be integrated with more recent results, particularly those in the field of vitamin D metabolites and I shall communicate now the status of the art

Pollen grain viability in Parietaria judaica L. during the long blooming period and correlation with meteorological conditions and allergic diseases

Abstract: Pollen grain viability and starch presence in pollen were followed during the long blooming period (May-November) of Parietaria judaica, the most widespread pellitory in Italy, responsible for many cases of allergic diseases. Observations were carried out near Siena (Tuscany), in the years 1978 and 1979. Viability is high in late spring and early autumn, and pollen grains are starchy. The presence of starchless grains is always related to low viability: a production of pollen with a low viability occurs at the beginning and end of blooming, and also in summer, during drought periods. Pollen grain viability varies widely during the blooming period, and its variations are correlated to meteorological conditions, mainly rainfall and temperature. Allergic diseases due to pellitory, however, are mainly reported between April and July, and on the other hand a small amount of patients states that they suffer all the year round. The discrepancies between the periods of viable pollen production and of dec...

The human spermatozoon

Abstract: In recent years numerous studies have carried our knowledge of the human spermatozoon to a high level, and constitute a basis for the understanding of many cases of partial or complete infertility, as well as for a useful approach to the general problem of fertility control. Many of the investigations have involved electron microscopy, others have used chemical analysis of isolated cellular components. Useful data, first obtained on sperm in animals, recently has been confirmed in the human. This perhaps is an appropriate moment to gather these results together in a single review.

Evolution of the spermatozoon

Abstract: In the marine invertebrates which practise external fertilization, the spermatozoon is a flagellate cell, possessing an acrosomal complex made up of acrosome and perforatorium. In the animal phyla which adapted to the land after having achieved the internal fertilization, the spermatozoon acquires an elongate shape and develops accessory cytoskeletal organelles in the tail. In the highest forms, the flagellum seems to have become too long for a perfect motility; in such a condition, aberrant axonemal patterns can appear and aflagellate spermatozoa can also be found. At the apex of the terrestrial phyla, alternative motile apparatuses are achieved and also the acrosomal complex varies, according to the different structures of egg envelopes.

Non-enzymatic glycosylation of urinary proteins in type 1 (insulin-dependent) diabetes: correlation with metabolic control and the degree of proteinuria.

Abstract: In 18 control subjects and in 41 Type 1 (insulin-dependent) diabetic patients (13 with normal proteinuria, group A; 15 with microproteinuria, group B; and 13 with clinical proteinuria, group C), mean blood glucose, glycosylated haemoglobin and non-enzymatic glycosylated serum and urinary proteins, expressed as 5-hydroxymethylfurfural (5-HMF), were measured. In each group of diabetic patients, the levels of mean daily blood glucose, glycosylated haemoglobin and serum 5-HMF/mg protein were higher than in the control subjects. The urinary 5-HMF/mg proteinuria and the urinary/serum 5-HMF concentration ratio values were raised in group A and reduced in groups B and C. Moreover, they showed a negative correlation with 24-h urinary protein excretion in the control subjects and in each group of diabetic patients. The urinary 5-HMF/day in groups A, B and C was greater than in the control subjects. The urinary 5-HMF/day did not correlate with the mean daily blood glucose levels and, only in group A, did it correlate with serum 5-HMF and glycosylated haemoglobin. This suggests that, in this group, functional factors result in the increased renal elimination of 5-HMF and, therefore, of non-enzymatically glycosylated proteins. However, in the other groups of patients, this elimination depends on the degree of proteinuria.

Blood glutathione as a measure of exposure to toxic compounds

Abstract: Blood and liver glutathione levels were measured under the effect of an acute exposure to high doses of glutathione-depleting substances. Among direct-acting glutathione-depleting substances, diethyl maleate (0.3, 0.7 and 1.4 ml kg-1) caused a marked reduction of both blood and liver glutathione, whereas methyl iodide (320 mg kg-1) led to a decrease in liver glutathione stores immediately and in blood stores with a longer latency. Indirectly glutathione-depleting substances, like paracetamol (0.5-1.0 g kg-1) and styrene (250 mg kg-1), caused a reduction of liver glutathione, but not a similar reduction of blood glutathione. Blood glutathione is not a good measure of organ glutathione stores when dealing with indirect-acting glutathione-depleting substances.