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Biomedical subjects

E Di Paolo

Publications and source records attributed to E Di Paolo.

At least 19 recordsLinked to original sources
PubMed2001

[Food intake and nutritional status in a group of healthy elderly residing in a nursing home].

BACKGROUND: Aging is accompanied by a variety of economic, psychologic, and social changes that can compromise the nutritional status. Nutrition is an important aspect of healthful behaviour and a major component of general wellbeing of individuals throughout their life cycle. Nutritional intake appears to be an important factor contributing to aging. So, the purpose of this project was to evaluate diet and nutritional status. METHODS: Fifty-one healthy elderly subjects aged 70 years and older (31 F and 20 M), residing in a nursing home have been studied. Nutrient intake was assessed using 24-hour recalls; nutritional status was assessed using anthropometric measurements. The nutrient intakes for individuals were compared with the Italian Recommended Dietary Allowances (RDAs). RESULTS: Mean energy intake was 1,625 kcal; the average percentages of carbohydrate, protein, and fat were 54%, 16%, and 30%, respectively. The mean vitamin and mineral intake for participants met the RDAs except for calcium and selenium intakes. The mean fibre intake was low. The analysis of food products intake indicated that the above mentioned inadequacy in nutrient intake was the result of low consumption of milk and milk products containing calcium and a low consumption of integral foods or fruits containing fibre. CONCLUSIONS: The significance of sound nutrition education and the adverse impact of consumer misinformation about the benefits of these food choices becomes clear with the recognition that nutritional status influences the rate of physiologic and functional declines with age. This approach will require new efforts in consumer education sensitive to the needs and beliefs of older people.

English Abstract↗
PubMed1999

Role of charged amino acids conserved in the vasoactive intestinal polypeptide/secretin family of receptors on the secretin receptor functionality.

The secretin receptor is a member of a large family of G-protein-coupled receptors that recognize polypeptide hormone and/or neuropeptides. Charged, conserved residues might play a key role in their function, either by interacting with the ligand or by stabilizing the receptor structure. Of the four charged amino acids that are conserved in the whole secretin receptor family, D49 and R83 (in the N-terminal domain) were probably important for the secretin receptor structure: replacement of D49 by H or R and of R83 by D severely reduced both the maximal response to secretin and its potency. No functional secretin receptor could be detected after replacement of R83 by L. Mutation of D49 to E, A, or N had no effect or reduced 5-fold the potency of secretin. The highly conserved positive charges found at the extracellular ends of TM III (K194) and IV (R255) were important for the secretin receptor function, as K194 mutation to A or Q and R255 mutation to Q or D decreased the secretin's affinity 15- to 1000-fold, respectively. Six extracellular charged residues are conserved in closely related receptors but not in the whole family. K121 (TM I) and R277 (TM V) were not important for functional secretin receptor expression. D174 (TM II) was necessary to stabilize the active receptor structure: the D174N mutant receptors were unable to stimulate normally the adenylate cyclase in response to secretin, and functional D174A receptors could not be found. Mutation of R255, E259 (second extracellular loop), and E351 (third extracellular loop) to uncharged residues reduced only 10- to 100-fold the secretin potency without changing its efficacy: these residues either stabilized the active receptor conformation or formed hydrogen rather than ionic bonds with secretin. Mutation of K121 (TM I) to Q or L and of R277 (TM V) to E or Q did not affect the receptor functional properties.

Adenylyl Cyclases↗
PubMed1999

Mutations of aromatic residues in the first transmembrane helix impair signalling by the secretin receptor.

The secretin amino terminal residues are essential for high affinity binding to the cognate receptor and for the subsequent activation of adenylate cyclase. It has been already established that two basic residues of the receptor TM 2 are involved in the interaction with aspartate 3 of the ligand. The present work investigated the hypothesis that two conserved tyrosine residues of the TM 1 (Tyrosines 124 and 128) could also participate to the positioning of the amino terminus of the ligand. Tyrosines 124 and 128 were mutated into alanine and histidine residues, and the properties of the mutant receptors, expressed in CHO cells, were compared with those of the wild-type receptor. Mutation of tyrosine 124 to Ala or His decreased the affinity of the receptor for secretin, [Glu3]secretin, [Asn3]secretin and the secretin fragment 2-27, and reduced the intrinsic activity of [Asn3]secretin. Mutation of tyrosine 128 to Ala, but not to His reduced 50-fold secretin and [Asn3]secretin affinity but only 3-fold that of [Glu3]secretin. Secretin and [Glu3]Sn were equipotent in that mutant receptor. These results suggested that tyrosine 128 of the secretin receptor interacted directly with the [Asp3] residue of secretin and thus that the amino terminal domain of secretin interacts with amino acids buried in both the TM 1 and TM 2 helices.

Adenylyl Cyclases↗
PubMed1999

Properties of a recombinant human secretin receptor: a comparison with the rat and rabbit receptors.

A secretin receptor was cloned from a commercial human pancreatic complementary DNA (cDNA) bank. The amino acid sequence deduced from the nucleotide sequence differed slightly from the three different sequences previously published, suggesting a genetic polymorphism of the human receptor. The binding properties of the receptor were evaluated by testing natural secretin, related peptides, and synthetic analogs or fragments on membranes of Chinese hamster ovary (CHO) cells expressing the receptor after transfection. The second-messenger coupling was evaluated by adenylate cyclase measurement. The human secretin receptor was compared with the rat and the rabbit receptors. In the three animals species, rat and human secretin were equipotent; rabbit secretin was equipotent on human and rabbit secretin receptors and less potent on the rat receptor. Similar data were obtained for the [Arg16]-secretin analog. Deletion of histidine 1 and replacement of aspartate 3 reduced the affinity of the peptides for the three receptors; however, the reduction was more pronounced on rat than on human and rabbit secretin receptors. Finally, the low affinity of the rat and human receptors for vasoactive intestinal peptide (VIP) was identical; the rabbit receptor, however, had a 20-fold higher affinity. Thus the human secretin receptor shows properties of both rat and rabbit receptors. Evaluation of the properties of chimeric receptors will be useful to fit the ligand on the receptors.

Adenylyl Cyclases↗
PubMed1998

Contribution of the second transmembrane helix of the secretin receptor to the positioning of secretin.

The secretin amino-terminal residues are essential for high affinity binding to its cognate receptor and for its biological activity. Mutation of the [Asp3] residue of secretin to [Asn3] decreased the ligand's affinity for the rat wild-type receptor 100-300-fold. Receptor mutations in the transmembrane 2 domain and the beginning of the first extracellular loop allowed the identification of three residues involved in recognition of the [Asp3] residue: D174, K173 and R166. Mutation of K173 and D174 not only reduced the secretin and [Asn3]secretin affinities, but also changed the receptor's selectivity as judged by a decreased secretin and [Asn3]secretin potency ratio. The most striking effect was observed when R166 was mutated to Q, D or L. This led to receptors with a very low affinity for secretin but an up to 10-fold higher affinity than the wild-type receptor for [Asn3]secretin. This suggested that R166, highly conserved in that subgroup of receptor, is a major determinant for the recognition of the [Asp3] of the ligand.

Adenylyl Cyclases↗
PubMed1998

The influence of alprazolam on the monoaminergic neurotransmitter systems in dysthymic patients. Relationship to clinical response.

The effects of alprazolam (1.5 mg/die) on the levels of the monoaminergic neurotransmitter metabolites, on the activity of the hypothalamic-pituitary-adrenal axis and on clinical outcome in subjects with primary late-onset dysthymia were investigated. Drug treatment significantly decreased plasma and urinary cortisol levels, serotonin platelet-bound and urinary 3-methoxy-4-hydroxyphenylglycol concentrations, while it increased plasma homovanillic acid (HVA) concentrations. Significant relationships were observed between neurochemicals and global scores or some items of the Hamilton Depression Rating Scale, before and after treatment. Patients responded positively (73%) to the therapy; clinical outcome was significantly correlated with plasma and urinary HVA levels. Collected data seem to support the hypothesis that central monoaminergic systems are in part involved in therapeutic response to alprazolam.

Adult↗
PubMed1997

Mutational analysis of extracellular cysteine residues of rat secretin receptor shows that disulfide bridges are essential for receptor function.

We attempted to express point-mutant secretin receptors where each of the 10 extracellular Cys residues was replaced by a Ser residue, in Chinese hamster ovary (CHO) cells. Six of the point-mutant receptors (C24-->S, C44-->S, C53-->S, C67-->S, C85-->S and C101-->S) could not be detected by binding or functional studies: the mutations resulted in functional inactivation of the receptor. In contrast, the four other point-mutant receptors (C11-->S, C186-->S, C193-->S and C263-->S) were able to bind poorly 125I-secretin, and to activate adenylate cyclase with high secretin EC50 values. These results suggest that cysteine residues 24, 44, 53, 67, 85 and 101 are necessary for receptor function, and that the two putative disulfide bridges formed by cysteine residues 11, 186, 193 and 263 are functionally relevant, but not essential for receptor expression. Secretin activated the adenylate cyclase through the quadruple mutant (C11,186,193,263-->S), the four triple mutants, and through double mutants C186,193-->S and C186,263-->S with a very high (microM) EC50 value, suggesting that, in the wild-type receptor, disulfide bridges are formed between C11-C186, and between C193-C263. Prior treatment with dithiothreitol resulted in a marked EC50 increase of the wild-type receptor and of those receptors with at least the two cysteine residues in positions 11 and 186, suggesting that the C11-C186 (but not the C193-C263) disulfide bridge was accessible to this reducing agent. Several results nevertheless indicated that, in mutant receptors, alternative disulfide bridges can be formed between cysteine 186 and cysteine 193 or 263, suggesting that these three residues are in close spatial proximity in the wild-type receptor.

Adenylyl Cyclases↗
PubMed1997

HLA-B44 subtypes and the chance of finding HLA compatible donor/recipient pairs for bone marrow transplantation: a haplotype study of 303 Italian families.

A total of 1176 HLA-A,B,DR haplotypes were reconstructed by typing 303 unrelated families referred to our laboratory during the last seven years for the search of HLA identical sibs in view of bone marrow transplantation. A total of 614 different three-locus haplotypes were found. Most of them (83.6%) were present only once or twice, whereas 24/614 (3.9%) were found 6-28 times each. HLA-B44 was present in 4 of these most frequent haplotypes. HLA-B44 has been implicated as the molecular target for bone marrow allograft rejection. Therefore, a better knowledge of the HLA-B44 haplotype relationships might prove useful for the programming of registries of unrelated bone marrow donors. Eighty five serologically defined HLA-B44 unrelated subjects, either one or both parents from the above families, were subtyped by a high-resolution sequence-specific oligonucleotide probing approach. Moreover, 34 unrelated potential donors recruited for those patients that did not find a suitable donor among their siblings were subtyped also for HLA-B44. B*4403, which accounted for 47/85 (55.3%) serologically defined B44 alleles, appeared in strong, statistically significant, linkage disequilibrium with HLA-A29, -A23 and -DR7. On the other hand, B*4402, which covered virtually all other B44 alleles, showed prevalent gametic associations with HLA-A2 and HLA-A24. The linkage disequilibrium between HLA alleles is the key for the low frequency of HLA-B44 mismatches in donors selected as HLA-A,B,DRB1 identical to patients waiting for unrelated bone marrow transplantation. If a given patient presents unusual haplotypes, the chance of finding HLA-B44 mismatches may be higher because of the presence of different haplotype relationships in the donors.

Bone Marrow Transplantation↗
PubMed1997

High prevalence of myocardial ischemia and vasoconstrictive hormonal release in hypertension during chronic renal failure.

OBJECTIVE: Indexes of myocardial ischemia and vasoconstrictive hormonal release were evaluated in order to investigate the difference between essential hypertension and hypertension during chronic renal failure. BACKGROUND: Arterial hypertension induces several cardiovascular alterations that reflect themselves either on the heart and/or on the coronary blood flow enhancing the cardiovascular risk. Since chronic renal failure can influence the neuroendocrine response, various mechanisms involved in hypertension during chronic renal failure are still unclear. High endothelin 1 (ET-1) levels have been found both in arterial hypertension and during chronic renal failure. Interestingly, either ET-1 or catecholamines seem also to be implied in the pathogenesis of myocardial ischemia. METHODS: 20 hypertensive uremic and 20 essentially hypertensive patients underwent echocardiographic wall motion and wall thickening analysis performed at baseline and immediately after the end of exercise. Simultaneously, myocardial perfusion was evaluated by 99mTc-MIBI-SPECT. In addition, plasma norepinephrine and ET-1 concentrations were measured at baseline and at peak exercise. RESULTS: The segmental radionuclide analysis showed a greater ischemic degree in hypertensive uremic patients. Yet, we were able to identify one or more regions of the left ventricle in which both systolic thickening measurements and wall motion after exercise were impaired. After exercise, wall thickening impairment was correlated with both wall motion abnormalities (r = 0.72, p < 0.01) and MIBI ischemic grade (r = 0.82, p < 0.001). Basal and after-exercise plasmatic norepinephrine and endothelin levels were higher in hypertensive uremic than in essentially hypertensive patients. Moreover, there was a significant correlation between increments in norepinephrine concentration and MIBI perfusion defects, and between the increment in ET-1 concentration and both MIBI perfusion defects, or kinetic alterations assessed by wall motion as well as by wall thickening. CONCLUSIONS: This is the first cross-sectional study in which a higher degree of myocardial ischemia has been observed in hypertensive uremic patients combined with an enhanced plasma release of both norepinephrine and ET-1. This phenomenon may contribute to enhance the cardiovascular risk of these patients.

Aged↗
PubMed1995

Properties of chimeric secretin and VIP receptor proteins indicate the importance of the N-terminal domain for ligand discrimination.

Two chimeras were obtained by substituting the DNA sequence encoding the N-terminal extracellular domain of the VIP and secretin receptors by the homologous DNA sequence encoding the secretin (N-Sn/VIP.r) and VIP receptor (N-VIP/Sn.r), respectively. These chimeric receptors were transfected and stably expressed in CHO cells. Their pharmacological properties were then compared to the corresponding recombinant "wild type" receptors, expressed in the same cell line. Binding data were obtained for the wild types and the N-VIP/Sn.r but not for the N-Sn/VIP receptor. Functional data (adenylate cyclase activation) were obtained in all cases. In order to minimize the effects of an excess of receptors and thus, to compare validly binding and functional data, we determined agonists EC50 values after down regulation of the receptors (i.e. after a pretreatment of the cells for 24 h with VIP or secretin). The order of potency of the peptides for receptor occupancy and adenylate cyclase activation indicated that the N-terminal extracellular domain of each receptor was the key element for discrimination between secretin and VIP.

Adenylyl Cyclases↗
PubMed1995

Pharmacological properties of two recombinant splice variants of the PACAP type I receptor, transfected and stably expressed in CHO cells.

Two splice variants of the pituitary adenylate cyclase activating polypeptide (PACAP) type I receptor (PACAP receptor and PACAP/HOP receptor isoform) were stably expressed in Chinese hamster ovary (CHO) cells that did not express constitutively receptors for this family of peptides. The PACAP/HOP receptor protein had a 28 amino acid extension in the C-terminal part of the third intracellular loop. The two cell lines studied, CHO 2-10 (PACAP receptor) and CHO 4-12 (PACAP/HOP receptor) expressed a receptor density of 4.6 +/- 0.3 and 2.6 +/- 0.2 pmol/mg protein, respectively, with corresponding Kd values of 14.2 +/- 2.0 and 8.2 +/- 1.0 nM for [Ac-His1]PACAP-27 used as a tracer. Tracer binding was slightly decreased by GTP in both clones. The Kd values of PACAP-27, PACAP-38, vasoactive intestinal peptide (VIP), PACAP-27 fragments and analogues evaluated by binding competition curves, were higher in CHO 2-10 than in CHO 4-12, whereas the Kd for PACAP-38 fragments did not differ. The receptors were coupled to adenylate cyclase and the EC50 values were lower than the Kd values in both cell lines, suggesting an amplification process due to the existence of spare receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1994

Properties of the VIP-PACAP type II receptor stably expressed in CHO cells.

The VIP receptor cloned from rat lung (VIP1 receptor from the group of the PACAP-VIP type II receptors) was inserted into a mammalian expression vector and stably transfected into Chinese hamster ovary cells (CHO). Two clones were selected, expressing respectively a high (850 +/- 50 fmol/mg protein, for clone 3) and a low (100 +/- 30 fmol/mg protein for clone 16) number of receptors. Both clones had the same apparent Kd value of binding for VIP and related peptides. The receptor expressed had the same binding properties as the natural VIP receptor, judged from the relative potency of VIP and PACAP analogues and fragments. The EC50 value of adenylate cyclase activation were 3 to 10 fold lower in clone 3 than in 16. The values observed in clone 16 were closer to the binding Kd values. The differences between the two clones were explained by the existence of spare receptors in clone 3, since: (a) the relative efficacy of some fragments were lower in clone 16 than in clone 3; (b) pretreatment of the cells with VIP reduced the number of receptors in both clones and increased the EC50 value for VIP in clone 3 but decreased peptide efficacy in clone 16 without significant change of the EC50 value.

Adenylyl Cyclases↗
PubMed1993

Effects of pyridostigmine, corticotropin-releasing hormone and growth hormone-releasing hormone on the pituitary-adrenal axis and on growth hormone secretion in dementia.

Alterations of neuroendocrinological indices determined by the impaired regulating effects of cholinergic neurotransmission have been described in primary dementia. In this study we have evaluated the effects of acetylcholinesterase inhibition by pyridostigmine on growth hormone (GH), adrenocorticotropic hormone (ACTH) and cortisol secretion and on their responses to GH-releasing hormone (GHRH) and corticotropin-releasing hormone (CRH) in 7 patients with primary degenerative dementia and in 8 sex- and age-matched controls. Demented subjects showed higher cortisol basal levels and lower ACTH levels than controls. Pyridostigmine increased the GH response to GHRH in both groups, the effect being significantly enhanced in patients. An increase of ACTH and cortisol levels was found in both groups after pyridostigmine and CRH administration. Pyridostigmine pretreatment significantly increased the ACTH response to CRH in controls but not in patients. The obtained data may indicate that a muscarinic receptor upregulation and an impairment of somatostatinergic function are operative in the regulation of GH secretion in dementia. An underlying hyperactivity of the hypothalamic-pituitary-adrenal axis impairs the responses of ACTH and cortisol to CRH in this disorder.

Adrenocorticotropic Hormone↗
PubMed1992

Glutamate and GABA levels in CSF from patients affected by dementia and olivo-ponto-cerebellar atrophy.

The modifications in the CSF content of glutamate and GABA in patients afflicted with primary degenerative dementia (PDD) and olivo-ponto-cerebellar atrophy (OPCA) have been evaluated. Control subjects (with disk herniation) were also included in the study. The amino-acids assays were carried out utilizing enzymatic-bioluminescence technique. GABA levels in controls were 803 +/- 98 (n = 7) and in demented patients 702 +/- 98 (n = 7) pmol/ml. Glutamate levels were 2067 +/- 244 (n = 10) in controls, 1190 +/- 81 (n = 16) pmol/ml (vs controls p less than 0.01) in demented patients, and 1116 +/- 146 (vs controls p less than 0.01) in OPCA patients. These results suggest that CSF glutamate levels in severely demented patients might be a result of generalized neuronal loss in the brain with a reactive gliosis.

Age Factors↗