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S Cavallaro

Publications and source records attributed to S Cavallaro.

At least 37 records · Page 2Linked to original sources
PubMed1998

Time domains of neuronal Ca2+ signaling and associative memory: steps through a calexcitin, ryanodine receptor, K+ channel cascade.

Synaptic changes that underlie associative learning and memory begin with temporally related activity of two or more independent synaptic inputs to common postsynaptic targets. In turn, temporally related molecular events regulate cytosolic Ca2+ during progressively longer-lasting time domains. Associative learning behaviors of living animals have been correlated with changes of neuronal voltage-dependent K+ currents, protein kinase C-mediated phosphorylation and synthesis of the Ca2+ and GTP-binding protein, calexcitin (CE),and increased expression of the Ca2+-releasing ryanodine receptor (type II). These molecular events, some of which have been found to be dysfunctional in Alzheimer's disease, provide means of altering dendritic excitability and thus synaptic efficacy during induction, consolidation and storage of associative memory. Apparently, such stages of behavioral learning correspond to sequential differences of Ca2+ signaling that could occur in spatially segregated dendritic compartments distributed across brain structures, such as the hippocampus.

Animals↗
PubMed1998

Functional and molecular expression of PACAP/VIP receptors in the rat retina.

Receptor binding sites for pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP), positively coupled to adenylate cyclase, have been previously described in the retina of different mammalian species. In the present study, we determined the mRNA expression of PACAP/VIP receptor variants in the rat retina and investigated their coupling to phospholipase C in addition to adenylate cyclase. The two forms of PACAP, PACAP27 and PACAP38, induced a dose-dependent (1-100 nM) increase of cAMP and [3H]inositol monophosphate levels, whereas VIP stimulated, with lower potency and efficacy, cAMP formation only. Reverse transcription-PCR analysis in the rat retina detected both type-I (PACAP-R and PACAP-HOP splice variants) and type-II (VIP-I and -2) receptor-mRNAs. These data indicate that PACAP and VIP may interact with multiple receptor subtypes and activate one (VIP) or two (PACAP) signal transduction mechanisms in the rat retina.

Adenylyl Cyclases↗
PubMed1998

[Venous thrombosis. Experience in treatment, problems and perspectives].

BACKGROUND: Venous thromboembolic disease is a recurring reason for death, it is often well-known but sometimes misunderstood. The right treatment for this pathology should not follow one approach only, but several strategies with respect to the seriousness and extension of the several clinical pictures. In particular the pharmacological therapy tries to find the balance between risks and benefits. It is well-known that a weak treatment may cause an increase in the risk of the pathology extension or of recurrence; on the other hand, a therapy exceeding the well known ranges exposes to important hemorrhagic risk. METHODS: This work presents the personal seven years' experience in patients affected by limb venous thrombosis, in some cases combined with pulmonary embolism. For all patients the pathology seriousness has been assessed by echoduplex scanner and angio-CT, and routine serum electrolite and enzymes analysis and blood counts have been carried out. Different therapies have been investigated, their evolution over the years (on the basis of international and personal experience) and the follow-ups. RESULTS AND CONCLUSIONS: The foudamental implications of this experience are: the more remarkable use of vena cava filters do not improve clinical findings' follow-up. On the contrary, it can cause the extension of pathology; heparin therapy must start early and the therapeutic range must be reached as soon as possible. Any delay, together with immobilization, can cause the extension of the pathology; diagnosis research cannot stop at the acuity moment but it should study also the etiopathogenetic picture. This affects the future therapeutic strategy in the follow-up; fibrinolitic therapy, once recommended for extended femoral-iliac thrombosis, should be used for serious levels of the same pathology and only for patients with low haemorrhage risk, or for patients affected by periodic pulmonary thromboembolism which may compromise haemodynamic system.

Anticoagulants↗
PubMed1997

Late memory-related genes in the hippocampus revealed by RNA fingerprinting.

Although long-term memory is thought to require a cellular program of gene expression and increased protein synthesis, the identity of proteins critical for associative memory is largely unknown. We used RNA fingerprinting to identify candidate memory-related genes (MRGs), which were up-regulated in the hippocampus of water maze-trained rats, a brain area that is critically involved in spatial learning. Two of the original 10 candidate genes implicated by RNA fingerprinting, the rat homolog of the ryanodine receptor type-2 and glutamate dehydrogenase (EC 1.4.1.3), were further investigated by Northern blot analysis, reverse transcription-PCR, and in situ hybridization and confirmed as MRGs with distinct temporal and regional expression. Successive RNA screening as illustrated here may help to reveal a spectrum of MRGs as they appear in distinct domains of memory storage.

Animals↗
PubMed1997

Reversible antisense inhibition of Shaker-like Kv1.1 potassium channel expression impairs associative memory in mouse and rat.

Long-term memory is thought to be subserved by functional remodeling of neuronal circuits. Changes in the weights of existing synapses in networks might depend on voltage-gated potassium currents. We therefore studied the physiological role of potassium channels in memory, concentrating on the Shaker-like Kv1.1, a late rectifying potassium channel that is highly localized within dendrites of hippocampal CA3 pyramidal and dentate gyrus granular cells. Repeated intracerebroventricular injection of antisense oligodeoxyribonucleotide to Kv1.1 reduces expression of its particular intracellular mRNA target, decreases late rectifying K+ current(s) in dentate granule cells, and impairs memory but not other motor or sensory behaviors, in two different learning paradigms, mouse passive avoidance and rat spatial memory. The latter, hippocampal-dependent memory loss occurred in the absence of long-term potentiation changes recorded both from the dentate gyrus or CA1. The specificity of the reversible antisense targeting of mRNA in adult animal brains may avoid irreversible developmental and genetic background effects that accompany transgenic "knockouts".

Animals↗
PubMed1997

Liver is not the unique site of synthesis of beta 2-glycoprotein I (apolipoprotein H): evidence for an intestinal localization.

Apolipoprotein H is a protein of about 50 kilodaltons, structurally related to the regulators of the complement activation family. Its physiological function is poorly understood but it has been implicated in lipid metabolism and coagulative pathways. The major site of synthesis is thought to be the liver. Several reports indicate that apolipoprotein H is the antigen of the antiphospholipid antibodies and also behaves as an acute-phase reactant. Moreover, 40% of plasma apolipoprotein H is associated with very low-density lipoprotein, high-density lipoprotein, and postprandial chylomicrons. In this study we investigated other sites of synthesis by reverse transcription/polymerase chain reaction and we found apolipoprotein H mRNA expression in intestinal cell lines and tissues. Immunohistochemistry was performed on various fresh and paraffin-embedded tissues and apolipoprotein H was immunolocalized in the cytoplasm of hepatocytes and epithelial cells from colon and jejunum. This study indicates that apolipoprotein H is expressed at both mRNA and protein levels in enterocytes.

Apolipoproteins↗
PubMed1996

Calexcitin: a signaling protein that binds calcium and GTP, inhibits potassium channels, and enhances membrane excitability.

A previously uncharacterized 22-kDa Ca(2+)-binding protein that also binds guanosine nucleotides was characterized, cloned, and analyzed by electrophysiological techniques. The cloned protein, calexcitin, contains two EF-hands and also has homology with GTP-binding proteins in the ADP ribosylation factor family. In addition to binding two molecules of Ca2+, calexcitin bound GTP and possessed GTPase activity. Calexictin is also a high affinity substrate for protein kinase C. Application of calexcitin to the inner surface of inside-out patches of human fibroblast membranes, in the presence of Ca2+ and the absence of endogenous Ca2+/calmodulin kinase type II or protein kinase C activity, reduced the mean open time and mean open probability of 115 +/- 6 pS K+ channels. Calexcitin thus appears to directly regulate K+ channels. When microinjected into molluscan neurons or rabbit cerebellar Purkinje cell dendrites, calexcitin was highly effective in enhancing membrane excitability. Because calexcitin translocates to the cell membrane after phosphorylation, calexcitin could serve as a Ca(2+)-activated signaling molecule that increases cellular excitability, which would in turn increase Ca2+ influx through the membrane. This is also the first known instance of a GTP-binding protein that binds Ca2+.

Amino Acid Sequence↗
PubMed1996

Tissue-specific and developmental expression of pituitary adenylate cyclase-activating polypeptide (PACAP) receptors in rat brain.

The two forms of pituitary adenylate cyclase-activating polypeptide, PACAP27,and PACAP38, are novel members of the vasoactive intestinal peptide (VIP)/secretin/glucagon family of peptides. PACAP receptors that are positively coupled to adenylate cyclase and phospholipase C have been recently identified. We examined the expression of PACAP receptors in the rat cortex, hippocampus, cerebellum and hypothalamus during postnatal development. Functional studies revealed PACAP stimulation of cAMP formation in all the brain areas examined and [3H]inositol monophosphate ([3H]InsP) accumulation only in the cerebellum and hypothalamus. Throughout development, the efficacy or PACAP in stimulating cAMP formation slightly increased in the cortex and hypothalamus and decreased in the hippocampus and cerebellum; PACAP stimulation of [3H]InsP formation decreased in the cerebellum and remained steady in the hypothalamus. The effects of PACAP27 and PACAP38 on cAMP levels and inositol phospholipid hydrolysis were dose-dependent between 1 and 100 nM. In the same brain areas, treatment with VIP increased cAMP formation at doses greater than 100nM and failed to affect [3H]InsP content, thus suggesting the existence of type-1 PACAP receptors. The reverse transcription polymerase chain reaction (RT-PCR) was used to analyse the mRNA expression of type-1 PACAP receptor splice variants. PACAP receptor gene expression in the central nervous system was regulated in a developmental- and tissue-specific manner. The PACAP-R transcript was detected in all the brain areas examined whereas PACAP-R-hop mRNA ocurred only in the cerebellum and hypothalamus. The different expression profiles and functional properties of PACAP receptors in the developing rat brain suggest an involvement of PACAP in histogenesis, maturation and neurotransmission.

Adenylyl Cyclases↗
PubMed1996

Characterization of vasoactive intestinal peptide/pituitary adenylate cyclase-activating peptide receptors in human benign hyperplastic prostate.

Vasoactive intestinal peptide (VIP) is an important member of the group of neuropeptides that appears to be involved in the regulation of prostatic growth and function. Here we studied VIP receptors in membranes from human benign hyperplastic prostate. Accordingly to observations in rat prostatic membranes, [125I]VIP binding to human prostatic membranes suggested two classes of binding sites with high Kd = 0.22 nM) and low (Kd = 37.7 nM) affinities. VIP bound in human and rat membrane preparations to a common VIP/pituitary adenylate cyclase-activating peptide (PACAP) receptor, as VIP, PACAP-27, and PACAP-38 were equipotent for competition of [125I]VIP binding. A PACAP-preferring receptor appears to be expressed in human prostate, since [125I]PACAP binding was displaced with more potency by PACAP than by VIP, and a messenger RNA corresponding to type I PACAP receptor was found. Cross-linking experiments suggested a VIP receptor of about 71 kDa in human and 52 kDa in rat prostates. The binding of [125I]VIP to membranes and the labeling of the bands observed after electrophoresis were competitively inhibited by GTP, suggesting the coupling of VIP receptors to a G protein. Moreover, after solubilization and cross-linking, we observed a 120-kDa band that corresponded to the VIP receptor-alpha s association. VIP stimulated adenylyl cyclase activity in a dose-dependent manner, but the potency and/or the efficacy of VIP were lower in all human preparations studied than in rat prostatic membranes. In conclusion, this study clearly demonstrates the expression of VIP/PACAP common receptors associated with alpha s protein in human prostate and suggests that these neuropeptides could play an important and complex role in the physiology and pathophysiology of this human gland.

Adenylyl Cyclases↗
PubMed1996

Pituitary adenylate cyclase activating polypeptide prevents apoptosis in cultured cerebellar granule neurons.

The two forms of pituitary adenylate cyclase-activating polypeptide, PACAP27 and PACAP38, are two neuropeptide hormones related to the vasoactive intestinal peptide/secretin/ glucagon family of peptides. PACAP receptors that are positively coupled to adenylyl cyclase and phospholipase C have been identified in cultured cerebellar granule cells. Using the reverse transcription-polymerase chain reaction methodology, we demonstrated the expression of the PACAP-R and PACAP-R-hop mRNAs in cultured granule cells. When grown in the absence of serum or in low K+ concentrations, these neurons underwent apoptosis, a naturally occurring process characterized by cell shrinkage and internucleosomal DNA cleavage. We used these models of programmed cell death to study the relationship between PACAP receptor activation and neuronal apoptosis. Treatment with PACAP27 and PACAP38 reduced the development of apoptosis in a dose-dependent manner. The neuroprotective activity of PACAP was mimicked by high concentrations of vasoactive intestinal peptide or forskolin but not by carbamylcholine. Thus, we suggest that the activation of type I PACAP receptors may contribute to the survival of cerebellar granule neurons.

Animals↗
PubMed1995

Differentiation induces pituitary adenylate cyclase-activating polypeptide receptor expression in PC-12 cells.

The two forms of pituitary adenylate cyclase-activating polypeptide (PACAP), PACAP27 and PACAP38, are neuropeptide hormones related to the vasoactive intestinal peptide/secretin/glucagon family of peptides. PACAP receptors that are positively coupled to adenylyl cyclase and phospholipase C have been recently identified. We have investigated the expression of PACAP-Rs in undifferentiated and differentiated PC-12 cells. PACAP27 and PACAP38 failed to significantly increase cAMP or [3H]inositol monophosphate levels in undifferentiated PC-12 cells treated with vehicle, insulin-like growth factor I, or epidermal growth factor but greatly elevated levels after differentiation with nerve growth factor (NGF) or basic fibroblast growth factor. PACAP responsiveness increased significantly after 24 hr of NGF treatment, reaching a maximum within 4 days. At this time of differentiation, the effect of PACAP was dose dependent between 1 nM and 0.1 microM, whereas vasoactive intestinal peptide, at the maximal dose of 10 microM, slightly increased cAMP formation and failed to affect [3H]inositol monophosphate content. Radioreceptor assays, performed with 125I-PACAP27, revealed the induction of high affinity type I PACAP receptors in differentiated PC-12 cells. Using reverse transcription-polymerase chain reaction methodology, we showed the absence of type I PACAP receptor mRNAs in undifferentiated PC-12 cells and the expression of PACAP-R-hop mRNA after NGF or basic fibroblast growth factor treatment. The increased PACAP responsiveness induced by these growth factors in PC-12 cells may therefore result from the expression of the PACAP-R-hop isoform, positively coupled to both adenylyl cyclase and phospholipase C.

Animals↗
PubMed1993

Ectopic neuroblastoma of the thoracic wall: a case report.

A case of thoracic neuroblastoma arising at the anterior mammillary line from the inner surface of the second and third right rib in a 17-month-old male child is reported. Primary surgery allowed excision of the mass. According to the histologic, histochemical, and molecular features of the tumor, all consistent with the diagnosis of neuroblastoma stage 2, the patient underwent adjuvant chemotherapy and, after 2 years, he is alive and disease free at follow-up. In view of different clinical and therapeutical approaches, only a strict adherence to histopathologic criteria allows differentiation of neuroblastoma, even in a very unusual anatomical site, from other small-cell, peripheral neoplasms presumably arising from the embryonic neural crest, such as Askin's tumor, neuroepithelioma, and ectomesenchymoma. The site of origin of these tumors is an important diagnostic clue but can be misleading: only careful microscopic evaluation and molecular analysis lead to incontrovertible diagnosis and yield correct clinical management.

Diagnosis, Differential↗
PubMed1993

ACTH-induced mitochondrial DBI receptor (MDR) and diazepam binding inhibitor (DBI) expression in adrenals of hypophysectomized rats is not cause-effect related to its immediate steroidogenic action.

Diazepam binding inhibitor (DBI) is a 10-kDa polypeptide that is enriched in steroidogenic cells such as adrenocortical, Leydig, and glial cells. In these cells, DBI and some of its processing products bind to the mitochondrial DBI receptor (MDR), located on the outer mitochondrial membrane, and stimulate pregnenolone formation by facilitating cholesterol access to the inner mitochondrial membrane where the cytochrome P-450 side chain cleavage enzyme is located. To determine whether the ACTH-induced increase in adrenal steroidogenesis occurs via changes in DBI and MDR expression the adrenal content of DBI-like immunoreactivity (DBI-LI), the MDR density, and the expression of mRNAs encoding for DBI and MDR were studied in hypophysectomized rats treated with vehicle or ACTH. After 9 days from the hypophysectomy, the levels of DBI-like immunoreactivity (DBI-LI) and DBI-mRNA declined to approximately 20% of their normal value; in contrast MDR-density and MDR-mRNA levels were reduced by 50-60% and were associated to a similar decrease in the activity of type A monoamine oxidase, a marker for mitochondrial proteins. Prolonged administration of ACTH-R (ACTH in saline containing 16% gelatin, 15 U/kg/day, from day 7 after surgery) to hypophysectomized rats, completely restored DBI and MDR adrenal expression to values similar to those of sham-operated rats. Our results indicate that ACTH, probably acting at the transcriptional level, is required for the normal expression of DBI and MDR in adrenal cortex. Changes in DBI and MDR expression after ACTH administration were not temporally related to the immediate steroidogenesis induced by ACTH, and may reflect its long-term trophic action on adrenocortical cells.

Adrenal Glands↗