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Biomedical subjects

G Orlandini

Publications and source records attributed to G Orlandini.

At least 73 records · Page 4Linked to original sources
PubMed1989

Adequacy of haemodiafiltration.

In this study we have evaluated the influence of blood and ultrafiltration flow rate on the performance of five different high-flux membrane dialysers during haemodiafiltration. On the basis of clearance data we optimised the haemodiafiltration schedule of six uraemic patients to maintain an adequate midweek blood urea nitrogen concentration, while reducing the treatment time from 285 +/- 23 min to 210 min. After a follow-up of 6 months, we observed no difference in the clinical tolerance or in the biochemical parameters, compared to those found during the preceding haemodialysis period. Our data confirm the suggestions of other authors that haemodiafiltration is an effective alternative to conventional haemodialysis.

Adult↗
PubMed1989

Fine structure of bat deep posterior lingual glands (von Ebner's)

We studied the morphology and ultrastructure of the bat (Pipistrellus k.k. and Rhinolophus f.e.) deep posterior lingual glands (Ebner's glands) during hibernation, summer and after stimulation with pilocarpine. Ebner's glands are formed by serous tubulo-alveolar adenomeres and by an excretory system organized in intercalated ducts, long excretory ducts and a main excretory duct. The latter opens in the vallum which surrounds the circumvallate papillae and in the groove of the foliate papillae. The secretory cells, which lack basal folds, show abundant and dense granules (PAS+, Alcian blue -), microvilli (scarce during hibernation), a Golgi apparatus (well developed during summer and after stimulation with pilocarpine), a large nucleus and RER cisternae stacked at the basal pole. Centrioles, lipid droplets, heterogeneous bodies (in content and density, probably lipofuscin bodies), lysosomal multivesicular bodies and large, dense granules with a microcrystalline structure were also encountered. The lateral membranes of adjacent cells are joined by desmosomes; their interdigitations are neither numerous nor prominent during summer. Microfilaments, often gathered in small bundles, lie in the lateral, peripheral cytoplasm without any relation with desmosomes. In summer and particularly after stimulation with pilocarpine, the apical pole of the secretory cells is characterized by many long microvilli, pedunculated hyaloplasmic protrusions and secretory granules. During hibernation the lumen is filled with secretory material. Myoepithelial cells are arranged among secretory cells or between them and the basal lamina. The short intercalated ducts show similarities with the analogous ducts of the parotid gland. Striated ducts are absent. Excretory ducts are endowed with: a) an inner layer of cuboidal cells characterized by poorly developed cytoplasmic organelles, rare dense granules and a few small microvilli; b) an outer layer of basal cells lying on the basal lamina. Myoepithelial cells are absent. The main excretory duct is lined by a stratified epithelium with an inner layer of conical-pyramidal cells surrounded by two-three rows of basal cells. The conical-pyramidal cells show poorly developed organelles, an apical border with small short microvilli and a prominent terminal web.

Animals↗
PubMed1988

Effect of GnRH administration on blood polyamines and LH levels in normal and obese children.

Blood polyamines (spermidine and spermine) and LH levels have been studied after acute GnRH injection both in obese and normal weight children. In both groups LH values significantly increased after stimulation but reached higher peaks in normal children than in obese ones (P less than 0.05). On the contrary, polyamine levels increased significantly only in the normal weight children. LH peaked at 30 min and polyamines at 60 min after GnRH injection. On the basis of the proposed role of polyamines in hormone action and of our results, we suggest that polyamines may play a pivotal role in hormone responsiveness of hypothalamic-hypophyseal axis.

Adolescent↗
PubMed1988

The vasodilator effect of human atrial natriuretic factor (99-126) on human omental arteries.

The effect of synthetic human atrial natriuretic factor [ANF-(99-126)] on human omental arteries was investigated. The compound produced concentration-dependent relaxation, 10, 50 and 90% of maximum effect being observed at about 1, 10 and 100 nmol/l, respectively. These concentrations are considerably higher than those measured by radio-immunoassay in human plasma, even under extreme conditions (0.001-0.3 nmol/l). Therefore, ANF can dilate human resistance-size arteries, but whether it does so under physiological conditions has not been established.

Adult↗
PubMed1988

Dietary sodium change in primary aldosteronism. Atrial natriuretic factor, hormonal, and vascular responses.

Atrial natriuretic factor (ANF) may be physiopathologically involved in several clinical conditions including human hypertension. However, few data are available regarding this putative hormone and its relationship to aldosterone, blood pressure, and vascular responsiveness to alpha-adrenergic receptor stimulation in primary aldosteronism, a volume-expanded, low-renin model of human hypertension. For this reason, the behavior of supine and upright plasma ANF as related to aldosterone, blood pressure, and forearm alpha-adrenergic sensitivity (plethysmographic technique) to intra-arterial norepinephrine infusion was studied in eight patients with primary aldosteronism (five with adenomas, three with hyperplasia) before and at the end of two sequential 1-week low (20 mmol/day) and high sodium (200 mmol/day) diet periods. Basal, predict ANF concentrations decreased and increased after low and high sodium intakes, respectively. Furthermore, highly significant postural ANF decrements after 1 hour of standing occurred with each diet, although they were lower after the low than after the high sodium diet. Plasma aldosterone, either supine or upright, was insensitive to dietary sodium manipulations, suggesting the absence of ANF-mediated control of aldosterone secretion in our patients. In spite of about twofold higher ANF concentrations during the high than during the low sodium diet, forearm vascular sensitivity to intra-arterial norepinephrine infusion did not change during the study. Furthermore, systemic arterial blood pressure rose to a highly significant extent after dietary sodium content was increased, thus casting doubt on a role for ANF as an endogenous long-term modulator of systemic blood pressure and peripheral alpha-adrenergic sensitivity in patients with primary aldosteronism.

Adult↗
PubMed1988

The ultrastructure of the thyroid parafollicular cells of the marmot (Marmota marmota). Immunocytochemical localization of calcitonin and somatostatin.

We studied the topographical and ultrastructural characteristics of the parafollicular cells in the Marmota marmota and their seasonal changes. The parafollicular cells, together with the follicular cells, form the follicular epithelium occupying a peculiar basal position. Furthermore these cells are characterized by a clear cytoplasmic matrix and well developed cytoplasmic organelles. The latter synthesize and condense the secretory product which ultrastructurally is organized in secretory granule-vesicles with a scarcely electron-dense cottony content. Histochemically the secretion consists in a proteic complex (rich in alpha-amino acids and sulphonate proteins) with a minor glucidic component. The above metabolic activity closely relates with the seasonal metabolic changes and namely with calcium metabolism. The immunocytochemical reactions revealed the presence of calcitonin and, to a lesser extent, somatostatin. The morphological findings were compared with those observed in other hibernating mammalians and related to the calcium homeostasis.

Animals↗
PubMed1988

[The hypothalamic-hypophyseal neurosecretory system of the Alosa fallax nilotica. A histological and ultrastructural study].

We studied the morphological, histochemical and ultrastructural aspects of the hypothalamic-pituitary system in the Alosa fallax nilotica. The secretory activity of the preoptic nucleus and of the lateral tuberal nucleus was also investigated with regard to the gonadal growth and development during the reproductive sexual cycle and the changing migrational environmental conditions (anadromous and catadromous phases). The hypothalamic-pituitary system is formed by: centers of neurosecretion synthesis (parvo and magnocellular preoptic nucleus and lateral tuberal nucleus), a conduit system (preoptic infundibular-neurohypophyseal tract) and a collecting center (neurohypophysis intermediate lobe). The neurosecretory cells show two distinct types of secretory granules with different ultrastructural features probably representing the morphological expression of two distinct hormones. These cells show also characterizations of cytoplasmic areas related to peculiar cyclic functional stages concerned with the reproductive sexual cycle. We observed significant quantitative and qualitative changes of the neurons both in the parvo- and magnocellular preoptic nucleus and in the lateral tuberal nucleus during anadromous migration and during spawning and fertilization. Almost insignificant changes of the neurosecretory material were observed in the preoptic-pituitary tract and in the intermediate-neurohypophyseal lobe. The results show that the hypothalamic-pituitary neurosecretory system play an important role in the osmoregulation (magnocellular preoptic nucleus) and on the reproductive cycle (lateral tuberal nucleus). The system probably also controls some other metabolic activities (utilization of the stored material) linked to peculiar environmental and feeding conditions.

Animals↗
PubMed1988

Topography and ultrastructure of kidney lymphatics in some hibernating bats.

The kidney lymphatic system of some bats consists of intraparenchymal (interlobar, arcuate, and interlobular) and extraparenchymal vessels (capsular and prehilar connective). These vessels drain lymph via precollecting and prenodal collecting lymphatics into a hilar lymph node. There are no lymphatics in the renal medulla. The lymphatic vasculature (precollecting vessels excluded) is characterized by an endothelial wall lacking basal lamina and fenestrations. The endothelial cells, mostly rectangular in shape, are joined together by overlapping, end-to-end, and complex interdigitating junctions. Cytoplasmic expansions profile and thickness, intercellular junctions and particularly the different categories of uncoated vesicles (free or opened on luminal or abluminal surface) show qualitative and quantitative seasonal variations. Luminal and abluminal cytoplasmic processes appear (when analyzed in tridimensional reconstructions) as "intraendothelial channels." The increased number of these structures during summer characterizes them as dynamic elements and supports the concept of an active role played by them in transendothelial transport. Nevertheless, the main functional role is still ascribed (in addition to membrane transport mechanisms) to the vesicular system, also defined as the "vesicular route." We did not find any open intercellular junctions.

Animals↗
PubMed1987

Physiological stimuli to atrial natriuretic peptide secretion in normal humans.

We tested the response of plasma atrial natriuretic peptide (ANP) levels to the following physiological stimuli: postural changes; head-out water immersion; and physical exercise. Plasma ANP (p-ANP) levels were assessed by a specific, sensitive radio-immunoassay. Plasma ANP rose significantly when posture shifted from upright to recumbent for 1 h, but fell again to basal values after 10 min standing. Circadian variations did not affect the posture study. Head-out water immersion produced a prompt and remarkable (sevenfold) increase in p-ANP, with a plateau reached after 1 h and held until the end of the experiment (2 h). Plasma ANP levels were measured in 10 normal subjects performing supine treadmill exercise at 50% of maximum aerobic capacity for 30 min. Plasma ANP rose from baseline supine values after 15 min exercise, and remained elevated during the following 15 min exercise. During the recovery phase ANP showed a trend towards baseline values, with a 38% decrease attained after 30 min. We propose that the above tests could be used as ANP-stimulating manoeuvres in physiological and clinical conditions in man.

Adult↗
PubMed1986

A possible role for polyamines in cartilage in the mechanism of calcification.

The role of polyamines in cartilage is not known: they may be somehow related to the mechanism of calcification. In epiphyseal cartilage from calf scapulas, they are more concentrated in the ossifying area, where calcification takes place, than in the resting region. Spermidine is present in greater amounts than spermine and putrescine. Since ornithine decarboxylase (EC 4.1.1.17) is measurable only in the resting region of the tissue, it is in this area that polyamine biosynthesis occurs, while they accumulate in the ossifying area. Immunohistochemical evidence is obtained that only in the ossifying zone is spermidine extracellular. It is at this level that the matrix is rearranged to become calcified, and proteoglycans are dissociated and partially removed. The effect of polyamines on solutions of proteoglycan subunits has been studied in vitro by following variations of turbidity and viscosity. While in the presence of putrescine the specific viscosity decreases to asymptotic values, in the presence of either 30 mM spermidine or 2.5-10 mM spermine, the decrement is more marked. At the same concentrations, increase of the turbidity of proteoglycan subunit solutions was observed. Only spermidine showed the capacity of displacing proteoglycan subunits from a column of Sepharose 4B-type II collagen: at 15 mM concentration, about 90% of proteoglycans were removed from the column. Alkaline phosphatase activity, which plays an important role in calcification, is enhanced by spermidine and spermine. These results obtained in vitro support the hypothesis that polyamines may be related to calcification of preosseous cartilage.

Alkaline Phosphatase↗
PubMed1986

Intracellular location of polyamines associated to red blood cells.

The polyamines associated to human erythrocytes from healthy donors are mainly localized intracellularly. In fact chromatography of the erythrocytes on a resin which has a high affinity and capacity for polyamines does not affect the amount of polyamines associated to the erythrocytes. The low ability of spermine to adsorb to the external surface of erythrocytes at physiological ionic strength is suggested also by studies conducted with sealed ghosts. Also erythrocytes from patients with hematological and dermatological diseases which contain increased levels of polyamines show an intracellular location of these amines.

Chromatography, Affinity↗
PubMed1985

Pattern of human blood spermidine and spermine in prematurity.

Blood polyamines have been determined in preterm newborns (24-37 gestation weeks) during the first hours of life and until 20 days after birth. The most elevated polyamine concentrations were found in preterm newborns from the 24th-33rd gestational week. In all preterms, however, polyamine concentrations are higher than in full term newborns. In preterm infants two different patterns of blood polyamines appear in relation to the gestational age: in infants born at 24-34 wk, spermidine reaches the peak at 12 h and spermine shows high concentrations between 12 and 48 h. In infants born at 35-37 wk maximal concentrations of polyamines were reached at 12 h. Successively, in both groups the polyamines progressively decrease up to the 20th day, with some individual variations. Our results may provide a further support to the suggestion of a fetal genesis of polyamines and their involvement in fetal growth.

Female↗
PubMed1985

Cytoplasmic free [Ca2+] is increased in the platelets of spontaneously hypertensive rats and essential hypertensive patients.

The cytoplasmic free calcium concentration [( Ca2+]i) was assessed with the fluorescent dye Quin 2 in platelets and lymphocytes of spontaneously hypertensive rats (SHR), normotensive Wistar-Kyoto rats (WKY), essential hypertensive patients (EHP) and normotensive human control subjects (NCS). [Ca2+]i was significantly higher in the platelets of 8- and 20-week-old SHR in comparison with WKY. However, no difference was evident after weaning. Changes of cellular calcium in hypertensive rats apparently evolved simultaneously with the development of high arterial pressure. [Ca2+]i was significantly higher in platelets of EHP than in NCS. In lymphocytes of SHR, [Ca2+]i was not different from WKY at 4 and 8 weeks, but was increased at 14 weeks and at older ages. In EHP, intralymphocytic [Ca2+] was only modestly higher than in controls. On the whole, the results suggest that control of cytoplasmic calcium in these blood cells is similarly affected in human and animal models of primary hypertension.

Adult↗