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Biomedical subjects

G Fumagalli

Publications and source records attributed to G Fumagalli.

At least 55 records · Page 3Linked to original sources
PubMed1990

Morphology and neurophysiology of focal axonal injury experimentally induced in the guinea pig optic nerve.

A new model of focal axonal injury was reproduced by rapid and controlled elongation (uniaxial stretch) of the guinea pig optic nerve. Light microscopy study of optic nerve specimens after horseradish peroxidase injection into the vitreous of the animal's eye showed that axonal lesions were identical to those seen in human and primate post-traumatic diffuse axonal injury (DAI). The lesions were characterized by the formation of terminal clubs in severed axons and focal axonal enlargements in those axons that were lesioned-in-continuity. Visual-evoked potentials upon flash stimulation were recorded before and after injury. Mean amplitude and mean latency of occipital peaks were significantly elongated in the acute post-traumatic phase. Electron microscopy examination showed that the main axonal changes observed in this model were cytoskeleton disorganization, accumulation of axoplasm membrane-bound bodies at the site of terminal balls and dilatations-in-continuity and detachment of the axolemma from the myelin sheath. Such axonal alterations were similar to those found in many other biological models of central and peripheral axonal injuries in which the lesion was produced by invasive methods. This model is unique since it reproduces the same mechanism of injury and the identical lesions that have been demonstrated in humans and primates with post-traumatic (DAI).

Animals↗
PubMed1990

Developmentally regulated expression of calcitonin gene-related peptide at mammalian neuromuscular junction.

Using indirect immunofluorescence techniques, we have found that calcitonin gene-related peptide-like immunoreactivity is present in the neuromuscular junctions of somatic muscles as well as in almost all motor neurons of the lumbar enlargement of 1-week-old rats. It gradually decreases in both motor neurons and motor nerve endings as the animal grows up and completely disappears from the neuromuscular junctions in adult rats, persisting only in the motor nerve endings on the intrafusal fibers. In situ hybridization experiments have shown that the down-regulation of calcitonin gene-related peptide-like immunoreactivity is strictly related to a reduction in CGRP mRNA levels in the spinal motor neurons. These results indicate that the expression of CGRP is developmentally regulated in spinal cord alpha motor neurons. They also suggest that the peptide may play an important role at the immature neuromuscular junction.

Aging↗
PubMed1990

Regulation of turnover and number of acetylcholine receptors at neuromuscular junctions.

The number and metabolic stability of acetylcholine receptors (AChRs) at neuromuscular junctions of rat tibialis anterior (TA) and soleus (SOL) muscles were examined after denervation, paralysis by continuous application of tetrodotoxin to the nerve, or denervation and direct stimulation of the muscle through implanted electrodes. After 18 days of denervation AChR half-life declined from about 10 days to 2.3 days (TA) or 3.6 days (SOL) and after 18 days of nerve conduction block to 3.1 days (TA). In contrast, the total number of AChRs per endplate was unaffected by these treatments. Denervation for 33 days had no further effect on AChR half-life but reduced the total number of AChRs to about 54% (SOL) or 38% (TA) of normal. Direct stimulation of the 33-day denervated SOL from day 18 restored normal AChR stability and counteracted muscle atrophy but had no effect on the decline in AChR number. The results indicate that motoneurons control the stability of junctional AChRs through evoked muscle activity and the number of junctional AChRs through trophic factors.

Acetylcholine↗
PubMed1990

Deprivation of growth hormone-releasing hormone early in the rat's neonatal life permanently affects somatotropic function.

This work investigated in rats whether passive immunization against the endogenous GHRF in the early postnatal period led to permanent alterations of somatotropic function, similar to those observed in several human growth disorders, e.g. constitutional growth delay (CGD). On postnatal days 1, 2, 4, 6, 8, and 10, rats were given an anti-GHRF-serum (GHRH-Ab, 100 microliters/rat, sc) and were tested 1, 30, and 60 days after this treatment for basal and GHRH-stimulated GH secretion both in vivo and in vitro. GHRH-Ab reduced both basal and GHRF-stimulated GH secretion at all intervals and induced marked and chronic impairment of growth rate. The following differences were observed in the GHRH-Ab treated rats compared to normal rabbit serum-treated controls: 1) GH biosynthesis (incorporation of L-[3H]leucine into the electrophoretic band of GH): reduction of about 70%, 1 day but not 30 days after treatment; 2) Pituitary weight: significant reduction in absolute weight (30-40%) at all posttreatment intervals, and relative weight, 1 and 30 days after treatment. 3) Pituitary GH concentration: significant reduction in GH content (about 40%) but not concentration, at all posttreatment intervals; 4) Percentage of somatotrophs (immunocytochemistry): about 40% reduction 1 day, but not 30 and 60 days after treatment; 5) Hypothalamic somatostatin messenger RNA (mRNA) levels in situ hybridization): selective reduction (40%) in the periventricular nucleus 1 day but not 30 days after treatment; 6) Hypothalamic somatostatin cell number (immunocytochemistry): no significant changes in any hypothalamic area at any interval; 7) Pituitary somatostatin binding (in situ autoradiography): significant reduction, 1 day and 30 days after treatment; 8) Somatostatin inhibition of GH release "in vitro": somatostatin effect on GH release was reduced 30 days after treatment. These and previous data indicate that: 1) Transient deprivation of GHRF in the immediate postnatal period of the rat leads to permanent impairment of growth rate and somatotropic function; 2) GHRF deficiency itself or through reduction of GH secretion impairs somatostatin functions temporarily in the hypothalamus and permanently in the pituitary; 3) This rat model may mimic some forms of growth disorders in humans and holds promise as useful tools for investigating the underlying pathophysiological mechanisms.

Animals↗
PubMed1989

Ultrastructural localization of neuropeptides and GABA in rat dorsal horn: a comparison of different immunogold labeling techniques.

Several immunogold techniques were used to determine the ultrastructural localization of calcitonin gene-related peptide (CGRP), tachykinin, somatostatin, and gamma-amino-butyric acid (GABA) immunoreactivity in the dorsal horn of rat spinal cord. The immunocytochemical reactions were carried out directly on ultrathin sections from non-osmicated frozen tissue, non-osmicated low temperature-embedded (Lowicryl K4M) tissue, and osmicated epoxy-embedded material. Preservation of ultrastructural morphology and immuno-labeling efficiency were compared. Morphology of subcellular organelles was relatively good in ultra-thin frozen sections, which showed the highest immunoreactivity. However, only very small samples of tissue could be examined. Although there was relatively good immunolabeling in the Lowicryl K4M-embedded tissue, the ultrastructure of the neuropil, and particularly that of synapses, was poorly maintained. In contrast, the osmicated epoxy-embedded material offered optimal morphological preservation together with accurate subcellular localization of all antigens under study. The latter approach thus enabled clear visualization of CGRP, tachykinin, and somatostatin immunoreactivity restricted to large dense-cored vesicles (90-150 nm diameter) in many axonal and synaptic profiles in the superficial layers of the dorsal horn. CGRP- and tachykinin-positive profiles were also present in the tract of Lissauer. GABA immunoreactivity was present mainly in axons and terminals, and less frequently in somatic and dendritic profiles. In terminals, which often formed symmetrical synapses on immunonegative dendritic profiles, it was associated with small (30-60 nm diameter) clear vesicles and mitochondria. Double immunolabeling was possible on all preparations, but the osmicated, epoxy-embedded material clearly showed co-localization of peptides, especially of CGRP and tachykinins, within the same dense-cored vesicles in axonal fibers and/or terminals. On the other hand, peptide and GABA immunoreactivity were consistently seen in different nerve profiles. In a few cases, GABAnergic terminals were seen to synapse on tachykinin-positive fibers.

Animals↗
PubMed1989

Identification of subpopulations of bronchitic patients for suitable therapy by a dynamic rheological test.

The rheological properties of bronchial mucus samples, collected from randomly selected patients with chronic bronchitis by protected expectoration, under steady-state conditions without any exacerbation, were investigated in a double-blind multicentre study before and after five days of treatment with 4.5 g/day carbocysteine or with glucose as a placebo. Viscous and elastic properties of the mucus were measured with a rheometer fitted with coaxial cylinders set up in an oscillating instead of a rotating mode. The shapes of the ellipses obtained characterized the rheological properties of each bronchial mucus sample before and after treatment. Two different rheological patterns were observed. In the group of patients with initial viscosity greater than or equal to 10,000 mPa.s-1, carbocysteine treatment reduced viscosity and elasticity more than those of the placebo-treated patients. In the group of patients with viscosity lower than 10,000 mPa.s-1, the rheological modifications were the same for both groups. These results are discussed in terms of both the efficacy of carbocysteine and the necessity of rheological characterization of the patients before treatment into different groups, according to the rheological properties of their secretions, for better and targetted therapy with mucus modifying drugs.

Adult↗
PubMed1988

Increased level of soluble interleukin-2 receptor in advanced solid tumors: a preliminary study.

Both activated normal and transformed lymphocytes produce not only cell-associated but also cell-free IL-2R. Evidence of high serum concentrations of IL-2R appears to serve as a tumor marker in patients with lymphomas On the contrary, the role of soluble IL-2R in solid neoplasms has still to be defined. This investigation was carried out to analyze soluble IL-2R production in human solid tumors. The study included 35 patients with solid tumors (12 without and 23 with metastases), 58 healthy subjects and 6 lymphoma patients. Among cancer patients, lung and breast carcinoma were the two most frequent neoplasms. In each subject or patient, serum levels of IL-2R were measured by using an enzyme immunoassay. Moreover, in 14/23 patients with metastatic solid tumors, lymphocyte subpopulations were also evaluated. Serum levels of IL-2R were significantly higher in the cancer patients than in the normal subjects. The patients with metastatic solid tumors showed significantly higher mean levels than those without metastases, and similar to those observed in the lymphoma patients. Finally, there was no correlation between serum levels of IL-2R and the T4/T8 ratio, which was reduced in 5/14 cancer patients. Further studies will be needed to establish if elevated concentrations of IL-2R in the serum can contribute to the immunoincompetence of patients with disseminated solid neoplasms.

Adult↗
PubMed1988

Reduced platelet aggregability and increased vascular prostacyclin formation in a variant rat strain (IVA-SIV) with endogenous hypertriglyceridemia.

The Ivanovas-Sieve (IVA-SIV) rat represents the only available animal model of endogenous hypertriglyceridemia, in the absence of obesity and/or overt diabetes. Since plasma lipids/lipoproteins can modulate platelet reactivity and eicosanoid metabolism, these were examined in two groups of Charles River (CR) and IVA-SIV rats of identical age. The IVA-SIV rats had 2-fold higher plasma triglycerides and a 55% higher number of circulating platelets; the number of platelets was significantly correlated with triglyceridemia. Platelet reactivity to ADP and to collagen was significantly reduced in these animals, whereas the formation of thromboxane B2 did not differ from that of the CR. After perfusion of platelet-rich plasma (PRP) through the aortas of animals of the two strains, platelet aggregability, already lower in the IVA-SIV, was reduced to a higher extent compared to the CR. Increased levels of the prostacyclin metabolite 6-keto-PGF1 alpha were identified in the perfusate from the aortas of IVA-SIV rats. Platelets from these animals also showed an increased sensitivity to Iloprost, a stable prostacyclin analogue, with an IC50 1.7-fold lower compared to CR rats. Spontaneous hypertriglyceridemia in the IVA-SIV model is not associated with platelet hyperresponsiveness, but rather with a reduced sensitivity to major aggregants.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Acute effects of various chemotherapeutic combinations on hypophyseal and pineal hormone secretions in cancer patients.

It is known that prolonged therapy with cytotoxic drugs may affect the endocrine system. The present study was carried out to establish whether administration of chemotherapeutic drugs acutely influences hypophyseal and pineal activities. Nineteen patients affected by solid tumors were included in the study, 5 of whom were treated with CMF, 4 with FEC, 4 with CEV, and 6 with CDDP. Cytotoxic drugs were intravenously administered. Venous blood samples were collected at zero time and at 30, 60, 120 and 180 min after drug administration. On a separate occasion, venous blood samples were drawn during a saline infusion only. In each sample FSH, LH, GH, PRL, TSH, cortisol, melatonin and beta-endorphin were determined by the RIA method. The only significant changes observed in this study were a rise in PRL and a decrease in beta-endorphin after CDDP administration. Melatonin was enhanced after CDDP and CMF, and cortisol decreased after CMF and FEC, but their variations were not statistically significant with respect to those seen during saline infusion.

Adult↗
PubMed1987

Sorting of three secretory proteins to distinct secretory granules in acidophilic cells of cow anterior pituitary.

The distribution of three proteins discharged by regulated exocytosis--growth hormone (GH), prolactin (PRL), and secretogranin II (SgII)--was investigated by double immunolabeling of ultrathin frozen sections in the acidophilic cells of the bovine pituitary. In mammotrophs, heavy PRL labeling was observed over secretory granule matrices (including the immature matrices at the trans Golgi surface) and also over Golgi cisternae. In contrast, in somatotrophs heavy GH labeling was restricted to the granule matrices; vesicles and tubules at the trans Golgi region showed some and the Golgi cisternae only sparse labeling. All somatotrophs and mammotrophs were heavily positive for GH and PRL, respectively, and were found to contain small amounts of the other hormone as well, which, however, was almost completely absent from granules, and was more concentrated in the Golgi complex, admixed with the predominant hormone. Mixed somatomammotrophs (approximately 26% of the acidophilic cells) were heavily positive for both GH and PRL. Although admixed within Golgi cisternae, the two hormones were stored separately within distinct granule types. A third type of granule was found to contain SgII. Spillage of small amounts of each of the three secretory proteins into granules containing predominantly another protein was common, but true intermixing (i.e., coexistence within single granules of comparable amounts of two proteins) was very rare. It is concluded that in the regulated pathway of acidophilic pituitary, cell mechanisms exist that cause sorting of the three secretory proteins investigated. Such mechanisms operate beyond the Golgi cisternae, possibly at the sites where condensation of secretion products into granule matrices takes place.

Animals↗
PubMed1987

Morphometric and ultrastructural study of experimental venous thrombosis. Effects of defibrotide, an antithrombotic agent.

Defibrotide is a profibrinolytic agent which has potent stimulatory effects on vascular prostacyclin (PGI2) production and secretion. We have studied the effects of this substance on the morphological organization of venous thrombi by combining ultrastructural evaluation with histometric analysis. Thrombosis was induced by inserting a collagen-coated thread into the femoral vein of rabbits 2 h before sacrifice. The results show that Defibrotide is highly effective in reducing the size of the thrombus. This is due to combined profibrinolytic action and interference with platelet and leukocyte adhesion as indicated by results showing that: (i) large deposits of fibrin-like material are smaller and less abundant; (ii) platelet aggregates are smaller, and (iii) the density of leukocytes in thrombus is strongly decreased. Polymorphism is prominent in platelets which are indistinguishable from control suggesting that the primary site of action of Defibrotide is on adhesion. The inhibitory effect on leukocyte participation to the thrombotic process is probably due to PGI2 release and may be of relevance on maturation and aging of the thrombus.

Animals↗
PubMed1987

Role of endogenous prostaglandins in protection of rat gastric mucosa by tripotassium dicitrate bismuthate.

Gross and microscopic examination of rat gastric mucosa demonstrated that intragastric administration to rats of tripotassium dicitrate bismuthate (TDB), a colloidal bismuth compound, protects against gastric lesions induced by 85% ethanol. Indomethacin, a prostaglandin synthetase inhibitor, significantly blocked the gastric mucosal protective effect of TDB. The release of gastric mucosal prostaglandins was greater in animals treated with TDB than in control animals, both time- and dose-dependently. These results seem to indicate involvement of prostaglandins in the action of TDB.

Animals↗
PubMed1986

Prolactin response to thyrotropin-releasing hormone in early and advanced human breast cancer.

While prolactin (PRL) has been shown to stimulate the development of mammary carcinoma in several animal species, its role in human breast cancer remains to be established. To further investigate PRL secretion in human breast cancer, its basal levels and response to thyrotropin-releasing hormone (TRH) were evaluated in 16 patients (6 with no metastases and 10 with metastatic locations). The control group consisted of 19 healthy women. High PRL basal concentrations were seen in 2 patients only; no significant differences were found between the other patients and the normal subjects. The PRL increase induced by TRH administration was significantly higher in patients than in controls. Finally a change in the hormonal secretion was found after chemotherapy in 3 of the 5 patients in whom PRL response to TRH was evaluated either before or 10-12 days after a cycle of intravenous CMF adjuvant chemotherapy. These results demonstrate the existence of an exaggerated response of PRL to TRH in patients with breast cancer, even in the presence of normal basal levels. Moreover, they would seem to suggest a possible influence of CMF on PRL response to TRH stimulation.

Adult↗
PubMed1986

Purification and characterization of two plasma membrane domains from ejaculated bull spermatozoa.

Plasma membranes were detached from ejaculated bull spermatozoa by a brief sonication in a moderately hypotonic medium, and the released plasma membranes were partially purified by differential centrifugation. The resulting fraction was enriched 8- and 15-fold in alkaline phosphatase and 5' nucleotidase activities, respectively, compared with the starting sonicated spermatozoa. This total plasma membrane fraction was separated into two distinct fractions by equilibrium density centrifugation on a continuous linear sucrose gradient. Two peaks of light scattering material were formed at densities of 1.117 and 1.148 g/ml. The denser peak contained most of the protein of the plasma membrane fraction, whereas nearly all the concanavalin A binding activity was found in the lighter peak. The two bands had distinctly different polypeptide compositions when analyzed by SDS PAGE. Polyclonal antibodies were raised in rabbits against a major integral membrane glycoprotein of each fraction (Mr of 92,000 in the light peak and 98,000 in the dense peak). The two antigens were detected on the surface of intact spermatozoa by indirect immunofluorescence microscopy. The 92-kD protein (present in the lighter band) was detected only on the plasma membrane of the acrosomal and anterior postacrosomal regions of the head. The 98-kD antigen, present in the heavier band, was localized to the surface of the postacrosomal region of the head, to the principal piece of the tail, and to the connecting piece between the head and tail. The exclusive localization of the 92-kD polypeptide to the surface of the anterior portion of the head was confirmed by immunoelectron microscopy. These data show that the two fractions isolated on the sucrose gradient originate from different regions of the sperm cell plasma membrane.

Animals↗
PubMed1986

Ontogeny of growth hormone-releasing factor in the rat hypothalamus.

Using immunohistochemical techniques, we have studied the ontogenetic development of growth hormone-releasing factor (GRF) immunoreactive structures in the rat hypothalamus. Frozen sections of rat hypothalami were stained by the avidin-biotin complex (ABC) method using a specific antiserum against rat GRF. Immunoreactive GRF nerve terminals but not perikarya were first detected in rat fetuses on the 20th day of gestation in the external layer of the median eminence (ME). An increased number of immunoreactive nerve terminals in the ME were observed at 1 and 2 days of age. In addition, perikarya containing immunoreactive GRF-like material were observed in the arcuate nucleus (ARC). Rats at 5 days of age showed a further increase in GRF immunoreactive terminals, which now were also present in the internal layer of the ME. In 10- and 20-day-old rats immunoreactive nerve terminals were only moderately increased in the ME. GRF immunoreactive perikarya were observed in the ARC and also in proximity to the ventromedial nucleus. Moreover, GRF containing fibers were seen projecting from the ARC to the ME. Colchicine treatment of postnatal rats reduced immunostaining of the nerve animals in the ME, but did not affect that of the perikarya. These results are consistent with the view that the neural control of growth hormone secretion develops in the rat during late gestation and continues to mature during the early postnatal period.

Animals↗
PubMed1985

The major tyrosine-sulfated protein of the bovine anterior pituitary is a secretory protein present in gonadotrophs, thyrotrophs, mammotrophs, and corticotrophs.

The anterior pituitary is a complex secretory tissue known to contain several sulfated macromolecules. In the present study, we identified the major tyrosine-sulfated protein of the bovine anterior pituitary and investigated its cellular and subcellular localization. This protein consisted of two tyrosine-sulfated polypeptides of molecular weight 86,000 and 84,000 that were highly homologous to each other. In agreement with previous biochemical studies, the tyrosine-sulfated protein of Mr 86,000/84,000 was found to be secretory, as it was observed in the matrix of secretory granules by immunoelectron microscopy. Immunofluorescence studies indicated that the tyrosine-sulfated, secretory protein of Mr 86,000/84,000, referred to as TSP 86/84, was present in all endocrine cells except for some somatotrophic cells. Higher levels of immunoreactivity for TSP 86/84 were observed in gonadotrophic and thyrotrophic than in mammotrophic and corticotrophic cells. This appeared to result from the occurrence of TSP 86/84 in all secretory granules of the former cells and in only some secretory granules of the latter cells. We discuss the possibility that TSP 86/84 may have a role in the packaging of several distinct peptides hormones into secretory granules. One, though not the only, possible function of tyrosine sulfation may concern the sorting of this protein in the Golgi complex.

Animals↗