Showing papers by "University of Alcalá published in 1990"

Footprint analysis between three and seventeen years of age.

Abstract: Footprints of both feet were analyzed from 1676 schoolchildren of both sexes (1013 girls and 663 boys), aged between 3 and 17 years. The sample was divided into five age groups. In each footprint the Footprint Angle and the Chippaux-Smirak Index were obtained. Classification of individual shapes of foot arches and different types of foot morphology followed that used by Jaworski and Puch in 1987. A high percentage of lowered longitudinal medial arch in the youngest age group of the study was found. The percentage is lower in the older age groups. The longitudinal medial arch has a physiological development in the earlier years of growth.

Comprehension evaluation and regulation in learning from science texts

Abstract: Metacognitive variables influence students' learning from science texts. This article deals with the comprehension monitoring abilities of secondary school science students, one of the areas of metacognition which has drawn considerable attention from researchers. The aims of the study are, in particular: (a) to know the extent to which comprehension is monitored by secondary science students as revealed by inconsistency detection in manipulated science texts, and (b) to identify the strategies used to regulate comprehension by the students who detect the inconsistencies. The results indicate that knowing that one understands or fails to understand science texts could be as important a problem as understanding proper. Besides, some incorrect regulatory strategies used by students who notice the inconsistencies in the texts are identified. These could also have an annoying influence in the regulatory behavior of students when studying regular science texts.

Alcohol and bone disease.

Abstract: Alcohol is considered to be an important risk factor for various bone diseases but recent studies have shown that moderate alcohol intake can be beneficial to bone structure. Alcohol decreases osteoblastic activity, leading to decreased bone formation and defective mineralization. The changes reported in calciotropic hormones, mainly vitamin D and parathyroid hormone, are observed due in part to a deficient intestinal absorption of vitamin D and an inadequate synthesis of its hepatic metabolite, although greater emphasis has been given to dietary deficiencies or lack of exposure to sun. The changes in parathyroid hormone are not consistent and since there is no greater incidence of hyperparathyroidism in alcoholic patients, it suggests that alcohol does not have a long-term effect on the parathyroid glands. Alcohol increases calcitonin secretion acutely; calcitonin is an inhibitor of bone resorption and may be the mechanism by which moderate alcohol intake protects bone structure. Alcohol increases urinary calcium, magnesium and zinc excretion. Zinc deficiency has been postulated as a cause of oesteoporisis because it causes hypogonadism. The decrease in the levels of the gonadal hormones and the increase of cortisol, observed in chronic alcoholics, may indirectly cause osteopenia and aseptic necrosis. To these actions must be added the acidosis due to alcohol and the greater tendency of the alcoholic to fall, all of which influence bone changes and increase the incidence of bone fractures.

Macrozoobenthic community structure in the Ría de Foz, an intertidal estuary (Galicia, Northwest Spain)

Abstract: The community structure of the macrobenthic (>1 mm) fauna of an intertidal soft-bottom estuary, the Ria de Foz (Galicia, Northwest Spain) was investigated on 99 occasions during June, September and December 1984 and March 1985. The infaunal data were subjected to classification and ordination techniques. The analyses indicated that sediment characteristics (grain size, percentage silt-clay and organic-matter content) and tidal height are the most important factors governing the distribution and abundance of the intertidal communities. Three faunal assemblages were identified and examined in terms of species dominance, constancy and fidelity. In the clean sands of the outer estuary two main assemblages were distinguished; one, corresponding to the “boreal LusitanianTellina community”, inhabited the middle and lower tidal levels; the other, typical of a biocoenosis of sands and slightly muddy mediolittoral sands, inhabited the upper tidal level. The third benthic assemblage occupied the muddy sands and mud of the inner estuary and displayed some features in common with theCardium edule-Scrobicularia community described by Thorson.

Effects of photoperiod and temperature on testicular function in amphibians.

Abstract: Most amphibians present an annual testicular cycle characterized by a quiescent period (late autumn-winter) and a spermatogenic period (spring and summer). At the end of the period of spermatogenesis undifferentiated interstitial cells transform into steroid-secreting Leydig cells which regress in spring at the beginning of the new spermatogenetic cycle. The testicular cycle is controlled by the pituitary gonadotropin levels which are high in autumn and winter, low in spring and increase temporarily in the middle of summer. Photoperiod and temperature seem to be the most important external factors involved in the regulation of this cycle in many amphibian species since the colder the geographic area, the longer the quiescent period and the shorter the spermatogenic period. This suggests the occurrence of a potentially continuous cycle in these species, in contrast with that which occurs in other species having an endogenous rhythm of testicular function which is much less sensitive to environmental factors. Although the specific response to temperature can vary widely between species, the most frequent observation in amphibians with a potentially continuous cycle is that exposure to mild temperatures (15-20 degrees C, according to the spring temperatures of the different geographic areas) stimulates spermatogenesis even during the period of testicular quiescence. If this mild temperature is combined with a long photoperiod, complete spermatogenesis is attained. Experiments performed during the period of germ-cell proliferation (development from spermatogonia to round spermatids) indicated that low temperatures (below 11 degrees C) as well as short photoperiods (less than 8 h of light) hinder germ-cell proliferation. Moderately high temperatures (about 30 degrees C) do not impair this proliferation. In the newt Triturus marmoratus, it has been shown that an excessively long photoperiod (over 16 h) has the same effect as a short photoperiod. In this species eyes are not required for the testicular photoperiodic response. Photoperiod appears to have no effect on spermiogenesis (differentiation of round spermatids into spermatozoa), because once round spermatids are formed, spermiogenesis will occur even in total darkness. Mild temperatures seem to be necessary for spermiogenesis as well as for androgen biosynthesis because neither process will take place at extreme temperatures. Results on the effect of photoperiod in steroidogenesis differ between species.

Laminin, type IV collagen, and fibronectin in normal and cryptorchid human testes. An immunohistochemical study.

Abstract: Summary An immunohistochemical study of laminin, type IV collagen, and fibronectin was carried out in the testes of normal men and in the cryptorchid and contralateral scrotal testes of cryptorchid men from 2 to 40 years of age. The integrated optical density (IOD) per unit area of the lamina propria was measured in the immuno-stained sections. Fibronectin was found throughout the thickness of the lamina propria of the seminiferous tubules and in the interstitial connective tissue. No differences between normal and cryptorchid testes were found. Laminin was observed in the innermost part of the lamina propria of the seminiferous tubules and surrounding the endothelium of blood capillaries from infancy. No differences were found between normal and cryptorchid testes in the prepubertal period. In adult cryptorchid testes, laminin formed more numerous and deeper invaginations towards the seminiferous epithelium than in normal adult testes. Type IV collagen appeared throughout the thickness of the lamina propria of normal testes as well as in the wall of interstitial blood vessels. From infancy, the lamina propria of seminiferous tubules, but not blood vessel walls, showed lesser immunostaining for type IV collagen and a lower IOD of this component than did control tests from men of the same age. No differences between unilateral and bilateral cryptorchid-ism were found. The contralateral scrotal testes of cryptorchid males showed intermediate immunostaining for type IV collagen between that of normal control testes and that of cryptorchid testes. These findings suggest that the lamina propria of seminiferous tubules is lesioned at an early age in both cryptorchid and contralateral scrotal testes of cryptorchid men.

Cellulose Acetate Membrane Improves Some Aspects of Red Blood Cell Function in Haemodialysis Patients

Abstract: The present study was designed to evaluate the influence of two haemodialysis membranes of different biocompatibility on red blood cell function. Twelve patients were studied in two consecutive dialyses, with cuprophan and cellulose acetate. Blood was extracted at 0, 20 and 180 min after the beginning of the haemodialysis session and general haematological parameters, osmotic fragility, deformability, methaemoglobin concentration and malonyldialdehyde (MDA) red blood cell content were determined. Osmotic fragility improved with both membranes, but this improvement was more marked with cellulose acetate. MDA red blood cell content showed a tendency to increase after 3 h with cuprophan (114 +/- 11% of the basal value), whereas it tended to decrease with cellulose acetate (92 +/- 12%), the differences between the two groups being statistically significant. These results suggest that red cell function may improve by changing the characteristics of haemodialysis membranes. This phenomenon could be related to a better biocompatibility.

Functional anatomy of the human saccus lacrimalis.

Abstract: The relations between the saccus lacrimalis and different portions of the musculus orbicularis oculi were studied in orbital regions of human fetuses sectioned into numbered series. No insertions of the pars lacrimalis or Horner’s muscle on the saccus were found. These muscular fibres pass along the dorsal wall of the saccus and are separated from it by the reflex tendon of the ligamentum palpebrale mediale. The only muscular fibres that insert on the saccus are those that approach the anterior face of the saccus and the fornix. The fibres that insert on the anterior face proceed from the deep bundles of the pars preseptalis of the lower eyelids, and those that insert on the fornix derive from the deep bundles of the pars preseptalis of the upper eyelid.

Distribution and characteristics of the different astroglial cell types in the adult lizard (Lacerta lepida) spinal cord.

Abstract: The astroglial cells have been studied in the lizard spinal cord by means of metallic impregnations, immunohistochemical (glial fibrillary acidic protein) and ultrastructural methods. Three astroglial cell types have been immunohistochemically identified: ependymocytes, radial astrocytes and astrocytes. Transitional forms have also been observed. Scarce immunopositive ependymocytes were located in the dorsal and ventral regions of the ependyma. The radial astrocytic somata were located around the ependymal layer and their processes reached the subpial glia limitans. Typical astrocytes were the most abundant astroglial cell type; astrocytes located in the ventral horn showed a greater development than those of the dorsal horn. In the white matter, the astrocytes were large and their processes formed part of the subpial glia limitans; on some occasions, astrocytic cell bodies also formed part of this subpial limitans. Transitional elements between astrocytes and radial astrocytes were observed in both grey and white matter. The perivascular and subpial glia limitans were continuous and showed a strong immunoreactivity. The comparative analysis of our results in the lizard spinal cord with those in other vertebrate groups leads us to conclude that reptiles could represent the key group in the phylogenetic evolution of the astroglial cells in vertebrates.

Impulse control in obsessive-compulsive disorder: a biopsychopathological approach.

Abstract: 1 1 The dichotomy between behaviors (some pathological, some falling into the realm of criminality) characterized by an excessive impulsivity and others, such as obsessive-compulsive diserder (OCD), in which a high resistance towards inner or outer impulses dominate, can not be sustained any more 2 2 Classical descriptions of OCD include behavior patterns of low control of impulses, and individuals showing “low control of impulse disorders” are, more often than not, high controllers in the periods of time when the impulsivity is in the packground 3 3 Evidence from biological research and from treatment outcome studies also suggest common traits in the “hyponomic” ( impulsive) and “hypernomic” (obsessive) individuals, related to scretenin (5-HT) metabolism disturbances

Role of epithelium in agonist-induced contractile responses of guinea-pig trachealis: influence of the surface through which drug enters the tissue.

Abstract: 1. A method has been used in guinea-pig isolated tracheal rings to achieve selective drug entry from the adventitial or mucosal surface. A study has been made of the effects of epithelium removal on responses to spasmogens entering the tissue solely from the adventitial or the mucosal surface. 2. Cumulative concentration-response curves for KCl (1 to 100 mM), acetylcholine (0.1 microM to 10 mM) and histamine (1 microM to 1 mM) were constructed in intact and epithelium-denuded tracheal rings in circumstances where drug entry was unrestricted or restricted to the adventitial or mucosal surface. 3. Epithelium removal did not alter the responsiveness or sensitivity of tracheal rings to KCl either when drug entry was unrestricted or when drug entry was restricted to the adventitial or mucosal surface. 4. When acetylcholine entered from the mucosal or adventitial surfaces of intact tracheal rings its concentration-response curve was displaced to the right with respect to that obtained for unrestricted drug entry. A greater rightward shift was observed for mucosal drug entry than for adventitial drug entry. Epithelium removal potentiated acetylcholine entering from the mucosal surface to a greater extent (27.5 fold) than it potentiated acetylcholine entering from both surfaces (4 fold). Epithelium removal did not potentiate effects of acetylcholine entering from the adventitial surface alone. 5. In intact tracheal segments, concentration-response curves for histamine entering from the mucosal surface were displaced to the right compared with those for histamine entering in an unrestricted fashion or from the adventitial surface alone. This displacement was absent in epithelium-denuded preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetic and thermodynamic parameters for Schiff‐rase formation between 5′‐deoxypyridoxal and hexylamine

Abstract: The thermodynamic parameters involved in the formation of Schiff bases between 5′-deoxypyridoxal and hexylamine were determined at different pH values and a constant ionic strength (0.1 M). The overall and individual rale constants of formation and hydrolysis at 10, 15, 20, 25, and 30° were also determined. The enthalpy of the overall formation process was found to be negative at all the pH values assayed except the neutral, while its entropy was always positive. The results obtained show the great relevance of the phosphate group at C(5′) to the stabilization of the Schiff bases of pyridoxal 5′-phosphate.

Purification and properties of a β-glucosidase from Penicillium oxalicum autolysates

Abstract: A beta-glucosidase from the medium of an autolyzed culture of Penicillium oxalicum has been purified by tannic acid precipitation, sephacryl S-200, DEAE-Biogel, CM-Biogel and Mono Q successively. The purification process produced a homogeneous band in the SDS-PAGE that correspond to a Mr of 133,500. The enzyme had a pl of 4, and the active optima were found at pH 5.5 and 55 degrees C. The enzyme hydrolyzed different substrates showing maximum affinity against p-nitrophenyl-beta-D-glucoside with a Km value of 0.37 mM. The beta-glucosidase was inhibited by Glucono-D-lactone but not by glucose in the concentration range of 1 to 10 mM. The enzyme was adsorbed by Concanavalin-A-Sepharose.

Differences in kinetic characteristics and in sensitivity to inhibitors between human and rat liver alcohol dehydrogenase and aldehyde dehydrogenase

Abstract: 1. On the basis of kinetic properties and sensitivity to pyrazole inhibition, it is shown that liver alcohol dehydrogenase present in human mainly corresponded to class I and in rat to class ADH-3 which differed in a number of parameters. 2. Two different aldehyde dehydrogenase (ALDH) isoenzymes were detected in both human and rat liver. The human isoenzymes corresponded to the ALDH-I and ALDH-II type. 3. In the rat, one isoenzyme had low K m and showed similar activity than in human liver but differed in their sensitivity to both disulfiran and nitrofazole inhibition whereas the other presented high K m and showed greater activity than the human one. 4. Caution must be therefore paid when extrapolating to human subjects the data on ethanol metabolism obtained with rats.

High-density lipoprotein subpopulations as substrates for the transfer of cholesteryl esters to very-low-density lipoproteins.

Abstract: 1. Human total HDL (high-density lipoprotein), HDL2 and HDL3 were labelled in vitro by incubation with lipoprotein-deficient serum (LPDS) which contained either [3H]cholesteryl oleate or [14C]cholesterol under different conditions. The lipoproteins were then subfractionated by heparin-Sepharose column chromatography, and three subfractions (A, B and C) were successively eluted from each preparation of HDL, HDL2 and HDL3. When the labelling was done at 37 degrees C for 17 h, the subfractions were homogeneously labelled with [3H]cholesteryl oleate. However, when it was performed for only 30 min at 4 degrees C, the subfractions showed marked differences in the 3H specific radioactivity, which was much higher in the C fractions than in the others. 2. 3H-labelled HDL2 and HDL3 subfractions behaved differently under the precipitant action of heparin-Mn2+; fraction C (the richest in apolipoprotein E) produced the largest amount of radioactive and chemical precipitate. More 3H radioactivity, but not the cholesterol, was precipitated from HDL2 or HDL3 by the reagent, demonstrating that 3H-labelled HDL2 and HDL3 behave like their fraction C, which becomes labelled to the highest specific radioactivity despite having the smallest mass. 3. The incubation of 3H-labelled HDL subfractions with human LPDS and very-low-density lipoprotein (VLDL) at 37 degrees C increased the quantity of 3H radioactivity that was precipitated, in proportion to the amount of VLDL present in the media. These changes were attributable to the action of cholesterol ester transfer protein, since they did not occur at 4 degrees C or when human LPDS was replaced with rat LPDS. 4. Kinetics of the transfer of HDL [3H]cholesteryl oleate to VLDL showed a greater apparent Vmax for fractions A than for fractions B from either HDL2 or HDL3, whereas the apparent Km values were very similar, which suggest that this transfer process is influenced by the apoprotein composition of the donor lipoprotein.