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Biomedical subjects

E Pompili

Publications and source records attributed to E Pompili.

10 recordsLinked to original sources
PubMed1997

Identification of a short sequence highly divergent between beta-adrenergic-receptor kinases 1 and 2 that determines the affinity of binding to betagamma subunits of heterotrimeric guanine-nucleotide-binding regulatory proteins.

A 28-residue peptide (peptide G), derived from the C-terminal (W643-S670) of the beta-adrenergic receptor kinase (betaARK), was previously identified as the critical domain for binding to the betagamma subunits of the heterotrimeric guanine-nucleotide-binding regulatory protein (G betagamma). We observed that the 18-amino-acid core of this domain is poorly conserved between betaARK1 and betaARK2 and so may provide the basis for differences in G betagamma-binding properties. Specific antibodies raised against 18-residue peptides derived from the divergent sequences (peptides P1 and P2 for betaARK1 and betaARK2, respectively) competitively inhibited G betagamma-activation of the related betaARK subtype, confirming the involvement of this region in binding to G betagamma. Peptides P1 and P2 inhibited G betagamma-stimulated activity of both betaARK1 and betaARK2, with P2 being significantly more potent than P1 (IC50 of 179+/-5 microM for P2 and >500 microM for P1). The 28-residue peptides G showed the same relative inhibitory activities (IC50 = 48+/-5 microM for G2 and 146+/-8 microM for G1). This relative order of potency G2 > G1 approximately P2 > P1 was confirmed in a direct G betagamma-binding assay. No binding selectivity for the beta1, beta2, beta3 and beta4 G beta subtypes was observed. The EC50 value for G betagamma-activation of betaARK1 was about double of that for betaARK2, indicating a higher affinity between G betagamma and betaARK2, which is the expected result based on the findings with the peptides. These findings show that the 18-residue peptides P represent the shortest sequence of betaARK that can bind to G betagamma and provide a demonstration of a functional difference between the G betagamma binding domains of betaARK1 and betaARK2.

Amino Acid Sequence↗
PubMed1996

Marked decrease of plasma neuroactive steroids during alcohol withdrawal.

The neuroactive steroids allopregnanolone (ALLO) and allotet-rahydrodeoxycorticosterone (THDOC) are the most potent endogens positive modulators of gamma-aminobutyric acid (GABA) on GABAA receptors, a receptor system presumably responsible for some behavioral responses to alcohol withdrawal. In a group of nine alcoholic subjects, the levels of plasma ALLO and THDOC were markedly lower than those of control subjects during the early withdrawal phase (day 4 and 5), when anxiety and depression scores were higher. In contrast ALLO and THDOC plasma levels did not differ from those of control subjects during the late withdrawal phase when anxiety and depression scores were low. These results suggest that the decrease of neuroactive steroid biosynthesis may contribute to the withdrawal symptoms.

Adult↗
PubMed1996

Protease inhibitors in mouse skeletal muscle: tissue-associated components of serum inhibitors and calpastatin.

The proteinase inhibitor set in skeletal muscle is poorly characterized at present. This study was aimed to investigate in mouse skeletal muscle 1) the tissue-associated counterpart, if any, of serum protease inhibitors (which may also play antiproteolytic functions in tissues) and 2) calpastatin, a tissue inhibitor of calcium-activated neutral proteases (calpains). Triton-extracts were prepared from muscle homogenates of mice, which had been perfused extensively with phosphate buffered saline (PBS) (under deep anesthesia) to remove blood inhibitors. Among various inhibitors tested, the following muscle-associated inhibitors were identified by western-blotting: alpha-2-macroglobulin (185, 165, 35 kDa), alpha-1-antitrypsin (52 kDa), inter-alpha-trypsin inhibitor (220, 180 kDa) and calpastatin (70 kDa). Combined light microscope and confocal immunohistochemical experiments revealed that, in all muscles examined (soleus, plantaris, extensor digitorum longus) the above specific immunoreactivities were localized outside the muscle fibers (in periendomysium, blood vessel wall) as well as within them. Inter-alpha-trypsin inhibitor, however, completely lacked the intracellular localization. This wide distribution of proteinase inhibitors suggests that numerous muscular structures may be normally protected from unwanted proteolysis, thus providing an essential background for further studies on pathological models with altered proteolysis (m. dystrophy, denervation atrophy, etc.).

Animals↗
PubMed1995

[Immunochemical and immunohistochemical study of calpastatin, an endogenous calpain inhibitor, in the masseter muscle of the rabbit].

The calpains-calpastatin system (calcium-activated neutral proteases and endogenous inhibitor) seems to be, in the skeletal muscle, a fine enzymatic system of myofibrillar turnover regulation, in normal as well as pathological conditions (for ex., dystrophic muscle). The purpose of the research is to establish in qualitative and quantitative terms whether the level of calpastatin can evidence differences between a muscle in normal activity conditions and one having dysfunctional alterations experimentally induced. So the masseter muscle of rabbit in normal conditions and with experimentally modified occlusal plane has been used. Our results confirm the presence of the 68 KDa calpastatin in the masseter muscle. The presence of the inhibitor in the same subcellular structures in which the calpains have been detected (myofibrillars, sarcolemma, endomysial connective) has been confirmed. Finally, variations in calpastatin amount in the muscle of animals experimentally treated with respect to the controls have been found. Thus, calpastatin seems to act as a marker of muscle dysfunctions connected to occlusal plane alteration and to loss of vertical dimention.

Animals↗
PubMed1994

Immunohistochemical localization of serine-protease inhibitors in the human placenta.

Proteases and their inhibitors play a pivotal role in developmental and differentiative processes. In the present report we investigated the immunohistochemical localization of alpha 1-antitrypsin, alpha 1-antichymotrypsin and inter-alpha-trypsin inhibitor in first trimester as well as in term human placentas. For this purpose polyclonal antibodies against these serine-protease inhibitors were used. All inhibitors were expressed in the villous syncytiotrophoblast of first and last trimester placentas. Placental fibrinoid was positively stained for alpha 1-antitrypsin and inter-alpha-trypsin inhibitor throughout gestation. alpha 1-Antitrypsin and alpha 1-antichymotrypsin showed a strong immunostaining in the Hofbauer cells (first trimester and full term placentas). Extravillous cytotrophoblast was negative for the three protease inhibitors throughout gestation. The presence of the three inhibitors in the syncytiotrophoblast suggests a role in coagulative, invasive and immunomodulatory processes. Fibrinoid, staining for alpha 1-antitrypsin and inter-alpha-trypsin inhibitor, could also have an important immunoprotective function. The presence of protease inhibitors in the Hofbauer cells suggests an involvement of these cells in villous remodelling and differentiative processes.

Alpha-Globulins↗
PubMed1994

[The radiology of cerebral and paranasal sinus fungal lesions].

Pulmonary fungal infections have been increasingly reported in the patients with hematologic malignancies treated with aggressive chemotherapy and therefore presenting chemotherapy-induced leukopenia. The diagnosis of fungal infections in these severely immunocompromised hosts is of great importance, enabling the administration of an antifungal treatment to prevent potentially fatal fungal dissemination. This retrospective study was carried out to assess the most valuable conventional radiologic and CT features in the diagnosis of sinusal and cerebral mycosis infections. The authors reviewed their personal series of 71 patients with malignant hematologic diseases who developed a fungal lesion: twenty-eight cases were selected, 10 of them with an autoptic diagnosis of cerebral fungal lesions and 18 with a bioptic diagnosis of paranasal fungal lesions. In 10 patients with encephalic lesions, CT enabled four main types of tomodensitometric alterations with fungine etiology to be singled out--i.e., ischemic lesions, brain abscesses, granulomatoses and meningitis with possible brain parenchyma involvement. In 18 patients with fungal sinusitis, radiography and CT showed three main types of alterations: sinus opacities, pseudocystic images within the sinus and bone erosions. We conclude that in sinusal and cerebral fungal lesions no "specific criteria" can be established for the radiologic differential diagnosis between different fungine species and between fungine lesions with different etiologic agents.

Brain↗
PubMed1993

Immunogold ultrastructural localization of calpastatin, the calpain inhibitor, in rabbit skeletal muscle.

The ultrastructural localization of calpastatin, the endogenous inhibitor of the neutral calcium-dependent proteases (calpains), was investigated in rabbit skeletal muscle fibers using a polyclonal antibody against the 34 kDa form of the inhibitor isolated from rabbit. Quantitative studies by pre- and postembedding immunogold techniques revealed that the distribution pattern of the specific immunoreactivity included: 1) the sarcolemma with the adjacent cytoplasm (about 1 micron wide); 2) the myofibrils; 3) the mitochondria and 4) the nuclei (condensed as well as extended chromatin). Other cell substructures, such as lysosomes and the intermyofibrillar cytoplasm, were substantially devoid of immunoreactivity. Furthermore, in accordance to previous light microscope immunohistochemical experiments, an extracellular (endomysial) localization of specific immunoreactivity was confirmed. These results favour the view, which is also supported by a series of biochemical evidences, that calpastatin in rabbit skeletal muscle is present in cell structures also containing calpains and/or their putative substrates. The above multiple patterns of distribution also suggest that the muscular calpain-calpastatin system in skeletal muscle fibers may play different physiological roles in the various subcellular compartments.

Animals↗
PubMed1992

Calpain inhibitor in rabbit skeletal muscle: an immunochemical and histochemical study.

Calpastatin, the endogenous inhibitor of calcium-activated neutral proteases (calpains; EC 3.4.22.17), was studied in the rabbit vastus lateralis muscle by means of immunochemical and immunohistochemical techniques. Immunoaffinity chromatography using an antibody raised against the 34-kDa monomer of the 68-kDa dimeric inhibitor allowed us to isolate three main proteins (130-, 100- and 80-kDa). These proteins strongly inhibited calpain activity in muscle homogenate (I50 at about 50 micrograms/ml). Immunohistochemical experiments showed that calpastatin-related immunoreactivity was present in all fibre types (oxidative, glycolytic, oxidative-glycolytic) at both surface and cytoplasmic level. However, a few (20%) of the slow-twitch, oxidative fibres (5% of the total fibres), did not contain the cytoplasmic inhibitor. Specific immunoreactivity for calpastatin was also associated with the interstitial connective tissue. These results suggest that (i) calpastatin in skeletal muscle, as in other tissues, is present as a mixture of proteins of various molecular weights and (ii) the inhibitor may act not only in the cytoplasm but also at the surface or extracellular level.

Animals↗
PubMed1992

Inter-alpha-trypsin inhibitor-related immunoreactivity in human tissues and body fluids.

The distribution of inter-alpha-trypsin inhibitor (ITI) and related inhibitors was investigated in normal human tissues and body fluids by using an enzyme-linked immunosorbent assay (ELISA) and a streptavidin-biotin-peroxidase immunohistochemical technique. ITI-related immunoreactivity was localized in different cell types of various organs, such as liver, kidney, testis, gross intestine, cutis and brain. Specific immunoreactivity was also detected in serum, urine and bronchial mucus. This widespread, but not ubiquitous pattern of localization suggests that, in addition to the well known plasmatic role, ITI and/or ITI-related inhibitors may play a number of different physiological roles in various human tissues.

Adult↗