Biomedical subjects

V Pavone

Publications and source records attributed to V Pavone.

At least 73 records · Page 4Linked to original sources

PubMed1996

Delayed bilateral median nerve injury due to low-tension electric current.

A 6-year-old boy inserted an opened metal clip into a domestic electric outlet using the thumb and index fingers of both hands. He suffered low tension electrical shock with mild cutaneous signs. After a few weeks, he developed bilateral numbness and weakness of both hands. Electrophysiologic studies revealed bilateral median nerve sensorimotor axonal loss. Low tension electric shock could have produced delayed bilateral median nerve damage indirectly via spasm and thermal coagulation of the vasa nervorum. The pinching position of the fingers, the "circuit" of the metal clip, and the low resistance due to the thinness and moistness of child's skin may account for: 1) the absence of an electrical cutaneous burn and 2) easy volume conduction of current along the neurovascular bundle containing the median nerve.

Child↗

PubMed1996

Preconceptional and gestational evaluation of insulin secretion in patients with polycystic ovary syndrome.

The relationship between insulinaemia and obesity and glucose tolerance and the impact of pregnancy as risk factor for carbohydrate abnormalities were investigated in 91 consecutive patients with polycystic ovary syndrome (PCOS) aged 26-32 years. Fifteen normoglycaemic patients became pregnant within 6 months of the pregestational study using pharmacological induction of ovulation. Plasma concentrations of insulin and glucose after an oral glucose tolerance test (OGTT) were determined by immunoradiometric assay and glucose oxidase technique respectively. OGTT patients were classified according to their response as normoinsulinaemic (n = 46) or hyperinsulinaemic (n = 45). Impairment of glucose metabolism occurred in 12.1% (n = 11, 10 obese and one lean) of all PCOS subjects. Based on insulin secretion, 6.5% of normoinsulinaemic and 13.3% of hyperinsulinaemic patients had an impaired glucose tolerance and 2.3 and 2.2% respectively a non-insulin-dependent diabetes mellitus. Obese patients had higher values for area under the curve for insulin response to OGTT (I-AUC values) than lean patients, and the percentage above ideal body weight was greater in hyperinsulinaemic than in normoinsulinaemic patients. All hyperinsulinaemic (7/15) subjects who became pregnant developed an impairment of glucose metabolism during pregnancy. It is concluded that the PCOS population was at higher risk of developing carbohydrate abnormalities than the normal population of a similar reproductive age. Furthermore, those with abnormal insulin secretion at the pregestational stage may, during pregnancy, develop an impaired gestational glucose tolerance or gestational diabetes.

Adult↗

PubMed1996

In vitro activities of A-gliadin-related synthetic peptides: damaging effect on the atrophic coeliac mucosa and activation of mucosal immune response in the treated coeliac mucosa.

BACKGROUND: Gliadin amino acid sequence(s) responsible for toxicity in susceptible individuals have not been fully elucidated. Previous in vitro studies have suggested the presence of active sequences in the NH(2)-terminal part of the A-gliadin molecule. In this paper the in vitro activity of A-gliadin synthetic peptides 31-55, 31-43, and 44-55 has been investigated. METHODS: Organ culture of jejunal mucosa from untreated and treated coeliac patients was used. In the first system enterocyte height was used as a measure of peptide toxicity; in the second system evidence of activated mucosal cell-mediated immune response was sought. RESULTS: Peptides 31-55 and 31-43 were active on untreated coeliac mucosa at a concentration of 0.5 mg/ml and peptide 44-55 only at a concentration of 3 mg/ml. In in vitro-cultured treated coeliac mucosa peptides 31-55 and 31-43 at 1 mg/ml and peptide 44-55 at 3 mg/ml were able to induce enhanced epithelial expression of HLA-DR and 4F2 molecules and the appearance of CD25 positive cells. CONCLUSIONS: Our results suggest that 31-43 and 44-55 A-gliadin peptides are both active, even if to different extents. In vitro systems remain essential tools to screen material to be subsequently tested in vivo.

Amino Acid Sequence↗

PubMed1996

Ossifying fibroma of the skull in a patient with neurofibromatosis type 1. Case report.

Ossifying fibroma is a rare, benign, primary bone tumor that occurs most commonly in the mandible; a cranial vault location is extremely rare. In this report a case of symptomatic frontoparietotemporal ossifying fibroma with intracranial growth and cerebral displacement in a 12-year-old boy with neurofibromatosis type 1 (NF1) is described. Once excised the lesion did not recur. The skeletal system is frequently affected in NF1, and bone abnormalities are present in 50% to 70% of patients with this condition. The etiology of such lesions in NF1 is still controversial. To the authors' knowledge, ossifying fibromas of calvarial bones have not been described in NF1.

Child↗

PubMed1996

Evidence of a disturbance of the hypothalamic-pituitary-adrenal axis in polycystic ovary syndrome: effect of naloxone.

DESIGN: There are conflicting data on hypothalamic-pituitary-adrenal (HPA) axis function in women with polycystic ovary syndrome (PCOS). We have evaluated the HPA axis responses to naloxone in patients with PCOS compared to control subjects. PATIENTS: Twenty PCOS patients and 10 control women participated in the study. MEASUREMENTS: On days 5-6 of a spontaneous or progestin induced cycle each patient received an intravenous bolus (5 mg) of naloxone (time 0 min), followed by a 2-mg naloxone infusion in 100 ml of 0.9% saline over one hour. Samples were collected at -30, 0, 15, 30, 60, 90 and 120 minutes. ACTH and cortisol levels were measured in all plasma samples. RESULTS: PCOS patients showed significantly greater response than controls to naloxone of ACTH (peak value 261 vs 172% of basal value) and cortisol (peak value 237 vs 165% of basal value); also, ACTH and cortisol incremental areas were higher in PCOS patients (P < 0.05 and P < 0.04 respectively). The cortisol/ACTH ratio of AUCs percentage increase was found to be near unity for all patients without significant difference between PCOS and control groups, suggesting a direct correspondence between ACTH circulating levels and adrenal cortisol production. CONCLUSIONS: Polycystic ovary syndrome patients showed a hypothalamic-pituitary-adrenal axis hyper-responsiveness to naloxone infusion compared with control subjects. These data support the hypothesis that this disturbance could be central in origin.

Adolescent↗

PubMed1995

Proximal femoral focal deficiency (PFFD) and fibular A/hypoplasia (FA/H): a model of a developmental field defect.

Proximal femoral focal deficiency (PFFD) and fibular a/hypoplasia (FAH) are distinct malformations of the lower limbs. Both can occur as isolated defects or in association with other limb malformations. In fact, fibular defects frequently are present in PFFD, and, conversely, femoral abnormalities can be found in the presence of a typical FAH picture. We report on 5 patients with a variable combination of femoral and fibular defects. In one of them unilateral PFFD was associated with lateral foot defects, in the absence of fibular abnormalities, and with a phenotype similar to that observed in the femoral hypoplasia/unusual face syndrome (FH/UFS). Another patient had isolated PFFD on one side, with controlateral absence of femur, fibula, and tibia. Another patient had a PFFD, fibular hypoplasia, and abnormalities of fibular foot rays, and the last 2 patients, a father and son, had, respectively, bilateral foot malformations plus fibular and tibial hypoplasia in the father and a PFFD in the son. These observations represent a further demonstration of the existence of a fibular developmental field, and contribute to the definition of its spatial boundaries. The variable involvement of elements comprised in the developmental field can be explained by multifactorial etiology.

Abnormalities, Multiple↗

PubMed1995

Specific interaction between cyclophilin and cyclic peptides.

Cyclophilin A, a peptidyl-prolyl cis-trans is isomerase that catalyzes the otherwise slow isomerization of Xaa-Pro imidic bond, specifically binds the immunosuppressant cyclosporin A. Herein we report evidence on binding of cyclolinopeptide A and its synthetic analogue, [Aib5,6-D-Ala8]cyclolinopeptide, to bovine cyclophilin A. Binding experiments were monitored by fluorescence, CD, and second-derivative spectroscopies, evidencing no remarkable rearrangement of protein structure organization. The possibility that cyclolinopeptide A could act as a substitute of cyclosporin A in the immunosuppression modulation is also briefly discussed.

Amino Acid Isomerases↗

PubMed1995

Design of metal ion binding peptides.

Two cyclic and branched peptides (PLA and AZU) were synthesized with the aim of reproducing the active site of the blue copper proteins plastocyanin and azurin. Both peptides, designed on the basis of the x-ray structures of Poplar plastocyanin and Alcaligenes denitrificans azurin, contain the same coordinating residues of the parent native proteins. The visible spectra of PLA in the presence of equimolar amount of Cu(II) strongly support the interaction between the peptide and copper(II) ion. The CD titration of AZU with the Hg(II) ion indicates for the formation of two species, [AZUHg]+ and [AZUHg2]3+ having binding constants (Keq) of 3.10(6) and 2.10(4) M-1, respectively.

Amino Acid Sequence↗

PubMed1995

Primary osteoma cutis--multiple café-au-lait spots and woolly hair anomaly.

An 11-year-old girl with typical features of primary osteoma cutis is reported. She demonstrated multiple areas of subcutaneous, asymptomatic, slow-growing nodules, mostly localized at the extremities. Radiographic evidence of soft tissue calcification and histologic confirmation of ectopic bone formation was obtained. She also showed café-au-lait spots, woolly hair and intrauterine growth deficiency.

Bone and Bones↗

PubMed1995

Intrafamilial phenotypic heterogeneity of the Poland complex: a case report.

Three cases of familial unilateral gluteal hypoplasia are reported. The index case in addition to having gluteal hypoplasia also has unilateral pectoral muscle hypoplasia. Another relative has unilateral symbrachydactyly of the distal phalanges of one foot. All four affected individuals in our pedigree were female. We propose that our cases are best classified as part of the Poland complex of anomalies. Our cases emphasize that intrafamilial phenotypic heterogeneity is possible within the Poland complex.

Buttocks↗

PubMed1995

The growth hormone response to growth hormone-releasing hormone is blunted in polycystic ovary syndrome: relationship with obesity and hyperinsulinaemia.

This study was designed to investigate the growth hormone (GH) secretory response to the growth hormone-releasing hormone (GHRH) test in women with polycystic ovary syndrome (PCOS). A total of 25 patients with PCOS (13 obese and 12 non-obese) and 15 normal ovulatory women (seven obese and eight non-obese) were included in this study. In the follicular phase patients were subjected to an oral glucose tolerance test (OGTT); 2 days later they underwent a GHRH test. Basal plasma concentrations of gonadotrophins, steroids and sex hormone-binding globulin were measured. Insulin and GH were assayed under the OGTT and GHRH test respectively. Based on the insulin response to OGTT in the PCOS group, nine patients were classified as normoinsulinaemic and 16 as hyperinsulinaemic; none of the patients of the control group had a hyperinsulinaemic response to OGTT. Obese patients showed a trend towards a lower GH response to GHRH. Moreover, hyperinsulinaemic patients showed a significantly (P < 0.05) lower area under the curve for secretion of GH (AUC-GH) as compared to normo-insulinaemic patients. All PCOS patients exhibited a markedly decreased response of GH to GHRH compared with the control population. Obese and hyperinsulinaemic PCOS patients were both found to have a lower response of GH to GHRH than all other groups. Despite the fact that obesity and hyperinsulinaemia have an additive influence on the impairment of GH secretion, our results suggest that other factors may also negatively affect GH secretion in PCOS.

Adult↗

PubMed1995

Effect of corticotropin-releasing factor on the pituitary-ovary axis in human luteal phase.

In order to test the possible negative effect of corticotropin-releasing factor (CRF) on the pituitary-gonadal axis, two gonadotropin-releasing hormone (GnRH) tests, on two consecutive days, were performed in five normally cycling women in the midluteal phase of the menstrual cycle. The first GnRH test was performed after 2 h during which time basal blood samples were collected every 10 min. On the second day, the GnRH test was repeated after a 2-h CRF infusion which was continued throughout the GnRH test. Our results demonstrate that while CRF increases cortisol levels it affects neither the basal nor the GnRH-stimulated gonadotropin levels. Similarly, both basal and luteinizing hormone (LH)-stimulated progesterone concentrations were not modified by the CRF infusion thereby also excluding a possible direct effect of the peptide on corpus luteum steroidogenesis.

Adult↗

PubMed1995

Aneurysmal bone cyst of the acromion: a case report.

The case of 6-year-old girl with an asymptomatic aneurysmal bone cyst of the acromion is reported. Such tumors are rarely located in the scapula and are especially rare in the acromion. The diagnosis was confirmed by biopsy and surgical resection of the lesion. Roentgenographic, CT and histologic features of the cyst are discussed.

Acromion↗

PubMed1994

Influence of lipophilicity on the biological activity of cyclic pseudopeptide NK-2 receptor antagonists.

A series of cyclic pseudopeptides of the formula cyclo(Leu psi[CH2NH]Xaa-Gln-Trp-Phe-beta Ala), where Xaa represents the residue of an alpha-amino acid, has been synthesized in order to establish the role of the Xaa side chain for tachykinin NK-2 receptor antagonist activity. Syntheses have been carried out in solid phase with either Fmoc or Boc strategy. The antagonist potency on NK-2 receptors in the hamster isolated trachea (HT) and the rabbit isolated pulmonary artery (RPA) bioassays increases with Xaa lipophilicity; cyclo(Leu psi[CH2NH]Cha-Gln-Trp-Phe-beta Ala) and cyclo(Leu psi[CH2NH]Asp(NHBzl)-Gln-Trp-Phe-beta Ala) resulted in being the two most active antagonists (pA2 = 9.06 and 9.26 on HT, respectively). A significant linear correlation was found between pA2 values determined in HT and RPA bioassays and capacity factors measured in reversed phase HPLC. The comparison between the biological activities of cyclic hexapeptides containing or not containing the aminomethylene moiety proved the crucial role of the pseudopeptide bond for determining high antagonist potency at the NK-2 receptor.

Alkylation↗

PubMed1994

Defect peptide chemistry: perturbations in the structure of a homopentapeptide induced by a guest residue interrupting side-chain regularity.

The fully blocked pentapeptide Tfa-(Deg)2-L-Abu-(Deg)2-OtBu (Tfa: triflouroacetyl; Deg: C alpha, alpha-diethylglycine; Otbu: tert-butoxy) adopts in the crystal state a regular, right-handed 3(10)-helical structure stabilized by three N--H...O=C intramolecular 1 < 4 (or C10) H bonds, as determined by an x-ray diffraction analysis. However, a Fourier transform ir absorption and 1H-nmr study strongly supports the view that in deuterochloroform solution the four Deg residues at both termini of the peptide main chain are involved in successive, fully extended C5 forms. A comparison with the stable, fully developed, multiple C5 conformation of Tfa-(Deg)5-OtBu indicates that incorporation of an Abu guest residue, interrupting the side-chain uniformity of the host (Deg)5 homopeptide, while altering only marginally the conformation in a solvent of low polarity, is responsible for a dramatic perturbation of the crystal-state structure.

Amino Acid Sequence↗

PubMed1994

Beta-alanine containing cyclic peptides with predetermined turned structure. V.

In the present paper we describe the synthesis, purification, single crystal x-ray analysis, and solution structural characterization by nmr spectroscopy, combined with restrained molecular dynamic simulations, of the cyclic hexapeptide cyclo-(Pro-Phe-beta-Ala-Phe-Phe-beta-Ala). The peptide was synthesized by classical solution methods and the cyclization of the free hexapeptide was accomplished in good yields in diluted methylenechloride solution using N,N-dicyclohexyl-carbodiimide. The compound crystallizes in the monoclinic space group P2(1) from methanol/ethyl acetate. The molecule adopts in the solid state a conformation characterized by cis beta-Ala6-Pro1 peptide bond. The alpha-amino acid residues are at the corner positions of turned structures. The Pro1-Phe2 segment is incorporated in a pseudo type I beta-turn, while Phe4-Phe5 is in a typical type I beta-turn. Assignment of all 1H and 13C resonances was achieved by homo- and heteronuclear two-dimensional techniques in dimethylsulfoxide (DMSO) solutions. The conformational analysis was based on interproton distances derived from rotating frame nuclear Overhauser effect spectroscopy spectra and homonuclear coupling constants. Restrained molecular dynamic simulation in vacuo was also performed to built refined molecular models. The molecule is present in DMSO solution as two slowly interconverting conformers, characterized by a cis-trans isomerism around the beta-Ala6-Pro1 peptide bond. This work confirms our expectations on the low propensity of beta-alanyl residues to be positioned at the corners of turned structure.

Amino Acid Sequence↗

PubMed1994

Beta-alanine containing cyclic peptides with turned structure: the "pseudo type II beta-turn." VI.

In the present paper we describe the synthesis, purification, single crystal x-ray analysis, and nmr solution characterization, combined with restrained molecular dynamic simulations, of the cyclic hexapeptide cyclo-(L-Pro-L-Phe-beta-Ala)2. The peptide was synthesized by classical solution methods and the cyclization of the free hexapeptide was accomplished in good yields in diluted methylene chloride solution using N,N-dicyclohexyl-carbodiimide. The compound crystallizes in the monoclinic space group P2(1) from methanol-dichloromethane solution. The two identical halves of the molecule adopt in the solid state two different conformations. One beta-Ala-L-Pro peptide bond is trans, while the second is cis. The molecule is present in dimethylsulfoxide d6 solutions as a mixture of conformational families. One of these corresponds to a C2 symmetrical molecule with both beta-Ala-Pro cis peptide bonds, while the second major conformation is very similar to that observed in the solid state. All Pro-Phe segments, both in the solid state and the symmetrical and unsymmetrical solution conformations, display phi, psi angles close to that of position i + 1 and i + 2 of type II beta-turns. In addition, the segments preceded by a trans beta-Ala-Pro peptide bond are characterized by a typical i<--i + 3 hydrogen bond, which is absent in the conformer containing a cis beta-Ala-Pro peptide bond. The latter conformation corresponds to a new structural domain we define as the "pseudo type II beta-turn."

Amino Acid Sequence↗

PubMed1994

Mixed conformation in C alpha, alpha-disubstituted tripeptides: x-ray crystal structures of Z-Aib-Dph-Gly-OMe and Bz-Dph-Dph-Gly-OMe.

We report here the synthesis and molecular structure in the solid state of fully protected tripeptides containing C alpha, alpha-diphenylglycine (Dph), namely Z-Aib-Dph-Gly-OMe (Aib: C alpha, alpha-dimethylglycine) and Bz-Dph-Dph-Gly-OMe. The molecular conformation around the Dph residue, containing two bulky substituents, is fully extended, while the Aib residue, containing two smaller groups on the C alpha atom, adopts the typical 3(10)/alpha-helical conformation. Gly residues, without substituents on the C alpha atom, show different conformational preferences. Each residue seems to behave, from a conformational point of view, independently from the presence of the other residues, and thus mixed local conformations (folded and extended) are present in the crystals. The nonconventional peptide synthesis, using the Ugi reaction, is also reported.

Amino Acid Sequence↗