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G Salvi

Publications and source records attributed to G Salvi.

At least 19 recordsLinked to original sources
PubMed2006

Skeleton and fractal scaling in complex networks.

We find that the fractal scaling in a class of scale-free networks originates from the underlying tree structure called a skeleton, a special type of spanning tree based on the edge betweenness centrality. The fractal skeleton has the property of the critical branching tree. The original fractal networks are viewed as a fractal skeleton dressed with local shortcuts. An in silico model with both the fractal scaling and the scale-invariance properties is also constructed. The framework of fractal networks is useful in understanding the utility and the redundancy in networked systems.

Escherichia coli↗
PubMed2003

Effective interactions cannot replace solvent effects in a lattice model of proteins.

Protein folding and protein design are among the most challenging problems of the past ten years in biophysics and molecular biology. For a given protein, it is possible to extract, from existing protein databases, a set of specific (i.e., belonging to the investigated protein) effective amino-acid (AA) interactions able to stabilize the native state. On the other hand, attempts to find global effective AA interactions, which would be able to stabilize all proteins at once, failed. Using a simple lattice model where the solvent degrees of freedom are (semi)explicitly taken into account, we show that the absence of global effective AA interactions is due to the solvent and that on this lattice model the solvent effects cannot be reproduced by amino-acid effective interactions.

Hydrophobic and Hydrophilic Interactions↗
PubMed2003

The crystal structure of polygalacturonase-inhibiting protein (PGIP), a leucine-rich repeat protein involved in plant defense.

Polygalacturonase-inhibiting proteins (PGIPs) are plant cell wall proteins that protect plants from fungal invasion. They interact with endopolygalacturonases secreted by phytopathogenic fungi, inhibit their enzymatic activity, and favor the accumulation of oligogalacturonides, which activate plant defense responses. PGIPs are members of the leucine-rich repeat (LRR) protein family that in plants play crucial roles in development, defense against pathogens, and recognition of beneficial microbes. Here we report the crystal structure at 1.7-A resolution of a PGIP from Phaseolus vulgaris. The structure is characterized by the presence of two beta-sheets instead of the single one originally predicted by modeling studies. The structure also reveals a negatively charged surface on the LRR concave face, likely involved in binding polygalacturonases. The structural information on PGIP provides a basis for designing more efficient inhibitors for plant protection.

Amino Acid Sequence↗
PubMed2002

Design of lattice proteins with explicit solvent.

Protein design is important to develop new drugs. As such, a knowledge of the correct model to use to design novel proteins is of the utmost importance. Here we show that a simple model where the solvent degrees of freedom are (semi)explicitly taken into account performs better than other existing models when compared to real data. Some consequences on the criteria to be used for protein design are discussed.

Journal Article↗
PubMed2002

A computerized version of EBIS evaluation chart and its opportunities in the rehabilitation program of TBI patients.

The need of rehabilitation programs for severely traumatic brain injured (TBI) patients is great and is growing, but these programs are long, costly and it would be very useful if we could demonstrate and quantify the benefits of our approaches. We think that scarcity of literature in this field is a consequence of the well known and real difficulty in this kind of investigations (too many variability factors, groups of population not homogeneous, ethical problems for double blind studies and so on). It is our opinion that EBIS Protocol could be a very useful instrument for the evaluation of rehabilitation programs benefits, provided that the protocol is used regularly for a long time after the acute phase and in many different TBI centres: in this way it would be possible to compare and to elaborate data concerning a large number of patients. This instrument could also become an opportunity for a continuous and more coordinated collaboration between rehabilitation centres of different countries. We think that this target is realistic only if we dispose of a commonly accepted computerized version of EBIS Protocol with a data exchange via Internet. Since 1996 we have been using a computerized version of the EBIS protocol for data archivation and follow up of TBI patients treated in our centre. The data bank concerns actually n. 341 TBI patients. Objective of the present research is the presentation of a computerized version of EBIS protocol. This program is freely available and it could contribute to a more common use of this evaluation tool. We thank particularly Prof. Truelle and Prof. Brooks who gave us the permission for the use of EBIS document.

Brain Injuries↗
PubMed2000

Extracellular H(2)O(2) induced by oligogalacturonides is not involved in the inhibition of the auxin-regulated rolB gene expression in tobacco leaf explants.

alpha-1,4-Linked oligogalacturonides (OGs) inhibit auxin-regulated transcriptional activation of a rolB-beta-glucuronidase (GUS) gene fusion in tobacco (Nicotiana tabacum) leaf explants (D. Bellincampi, M. Cardarelli, D. Zaghi, G. Serino, G. Salvi, C. Gatz, F. Cervone, M. M. Altamura, P. Costantino, G. De Lorenzo [1996] Plant Cell 8: 477-487). In this paper we show that inhibition by OGs is very rapid, with a short lag time, and takes place even after rolB promoter activation has initiated. OGs also induce a transient and catalase-sensitive accumulation of H(2)O(2) in the leaf explant culture medium. OGs with a degree of polymerization from 12 to 15 are required for both the inhibition of the auxin-induced rolB-driven accumulation of GUS and the induction of H(2)O(2) accumulation(.) However, OG concentration for half-maximal induction of H(2)O(2) accumulation is approximately 3-fold higher than that for half-maximal inhibition of rolB promoter activity. The inhibition of rolB promoter activity is not influenced by the addition of catalase or superoxide dismutase, suggesting that H(2)O(2) and superoxide are not involved in this effect. A fungal oligo-beta-glucan elicitor induces extracellular H(2)O(2) accumulation at comparable or higher levels than those observed with OGs, but does not prevent the auxin-induced accumulation of GUS. We conclude that H(2)O(2) produced upon treatment with OGs is not involved in the inhibition of the auxin-induced expression of the rolB gene.

Gene Expression Regulation, Plant↗
PubMed1998

Repolarization abnormalities in patients with idiopathic ventricular tachycardias.

STUDY POPULATION: Twenty patients without laboratory evidence of cardiac disease who underwent electrophysiological study because of recurrent ventricular tachyarrhythmias. PATIENTS AND METHODS: The study population was divided into two groups: group A (20 patients [six males and 14 females] mean age 42.2 +/- 13 years), with idiopathic ventricular tachycardia (VT), and group B (30 controls [10 males and 20 females] mean age 43.6 +/- 16 years). Noninvasive multiparametric analysis of the ventricular repolarization phase was performed on the standard 12-lead electrocardiogram by using a digitizer connected with a computerized system. The intervals JT, heart rate-corrected JT (JTc), JT apex (JTa), heart rate-corrected JTa (JTac), T apex T end (TaTe) and heart rate-corrected TaTe (TaTec) were measured and considered to be representative of the whole depolarization process. QT dispersions (QTeD) and QTc dispersions (QTecD) were calculated to assess the degree of spatial inhomogeneity of action potential duration. RESULTS: Patients in group A had higher JT (272 +/- 36 ms versus 265 +/- 25 ms, P = 0.01), JTc (336 +/- 28 ms versus 318 +/- 18 ms, P = 0.01), JTa (210 +/- 28 ms versus 185 +/- 28 ms, P = 0.001) and JTac (240 +/- 20 ms versus 215 +/- 13 ms, P < 0.001) values than those of patients in group B, despite shorter TaTe (71 +/- 10 ms versus 90 +/- 18 ms, P < 0.001) and TaTec (88 +/- 12 ms versus 110 +/- 12 ms, P < 0.001). Moreover, QTeD and QTecD were significantly longer in group A than in group B (55 +/- 18 ms versus 42 +/- 19 ms [P = 0.01] and 80 +/- 18 ms versus 55 +/- 28 ms [P = 0.001], respectively). CONCLUSIONS: Patients with idiopathic VT exhibit inhomogeneous prolongation of ventricular repolarization, due to a considerable increase in the initial part in association with a shorter terminal phase, as well as a greater dispersion of ventricular repolarization.

Adult↗
PubMed1997

Is chemoradiation feasible in elderly patients? A study of 17 patients with anorectal carcinoma.

BACKGROUND: Cancer in the elderly is becoming an increasing public health problem. Nevertheless, several authors have noted the relative lack of information regarding the treatment of cancer in the elderly. The aim of this study was to determine the tolerance of concomitant chemoradiation in patients age > or = 75 years with anorectal carcinoma. METHODS: The patients were selected for treatment on the basis of the absence of major concurrent diseases, normal blood count values, good cardiac and renal function, and good general condition (defined as not requiring personal assistance). Seventeen patients (8 men and 9 women with a median age of 79 years [range, 75-90 years]) were treated with concomitant chemoradiation (bolus mitomycin C, 10 mg/m2 on Day 1 and continuous infusion 5-fluorouracil [5-FU], 1000 mg/m2 for 24 hours on Days 1-4 [FUMIR]). The doses and volumes of pelvic radiation therapy ranged between 38-45 grays according to the primary tumor site and the intent of treatment (curative vs. palliative). RESULTS: The total incidence of Radiation Therapy Oncology Group Grade 3 acute toxicity was 18% (3 of 17 patients). Only 1 patient (6%) was unable to complete the treatment course. With a median follow-up of 26 months, no severe late toxicity was recorded. Sixteen of 17 had >50% reduction in the greatest dimension of the lesion, 6 patients had a complete response (2 rectal and 4 anal tumors), and 12 patients preserved their sphincter function. Of the four patients who had presented with pelvic pain, all had pain relief. Of the six patients who had presented with rectal bleeding, the bleeding was controlled in five patients. CONCLUSIONS: Concomitant chemoradiation according to the FUMIR schedule used in selected patients age > or = 75 years with anorectal carcinoma can be performed safely.

Aged↗
PubMed1997

Polygalacturonase-inhibiting proteins (PGIPs) with different specificities are expressed in Phaseolus vulgaris.

The pgip-1 gene of Phaseolus vulgaris, encoding a polygalacturonase-inhibiting protein (PGIP), PGIP-1 (P. Toubart, A. Desiderio, G. Salvi, F. Cervone, L. Daroda, G. De Lorenzo, C. Bergmann, A. G. Darvill, and P. Albersheim, Plant J. 2:367-373, 1992), was expressed under control of the cauliflower mosaic virus 35S promoter in tomato plants via Agrobacterium tumefaciens-mediated transformation. Transgenic tomato plants with different expression levels of PGIP-1 were used in infection experiments with the pathogenic fungi Fusarium oxysporum f. sp. lycopersici, Botrytis cinerea, and Alternaria solani. No evident enhanced resistance, compared with the resistance of untransformed plants, was observed. The pgip-1 gene was also transiently expressed in Nicotiana benthamiana with potato virus X (PVX) as a vector. PGIP-1 purified from transgenic tomatoes and PGIP-1 in crude protein extracts of PVX-infected N. benthamiana plants were tested with several fungal polygalacturonases (PGs). PGIP-1 from both plant sources exhibited a specificity different from that of PGIP purified from P. vulgaris (bulk bean PGIP). Notably, PGIP-1 was unable to interact with a homogeneous PG from Fusarium moniliforme, as determined by surface plasmon resonance analysis, while the bulk bean PGIP interacted with and inhibited this enzyme. Moreover, PGIP-1 expressed in tomato and N. benthamiana had only a limited capacity to inhibit crude PG preparations from F. oxysporum f. sp. lycopersici, B. cinerea, and A. solani. Differential affinity chromatography was used to separate PGIP proteins present in P. vulgaris extracts. A PGIP-A with specificity similar to that of PGIP-1 was separated from a PGIP-B able to interact with both Aspergillus niger and F. moniliforme PGs. Our data show that PGIPs with different specificities are expressed in P. vulgaris and that the high-level expression of one member (pgip-1) of the PGIP gene family in transgenic plants is not sufficient to confer general, enhanced resistance to fungi.

Enzyme Inhibitors↗
PubMed1997

[Neoadjuvant combined hormonal therapy and radiotherapy with external beam irradiation in prostatic carcinoma].

From January, 1991, to December, 1995, forty-two patients with prostatic cancer (T2-T4: 40 patients) were treated with a luteinizing hormone-releasing hormone (LHRH) analog (2 administrations before and 3 during irradiation), Flutamide (1 month) and external beam radiation therapy (45 Gy to the whole pelvis and a 20 Gy boost). All patients completed the protocol and the LHRH analog was continued for 1-6 months in 5 patients with partial response at the end of radiotherapy. The incidence of acute toxicity was low according to the Radiation Therapy Oncology Group and European Organization for Research and Treatment in Cancer score (grades 1-2; 19% hematologic, 36% intestinal and 38% urological toxicity). At a median follow-up of 21 months (range: 1-60 months), one patient had local disease progression and lung metastases and two had bone metastases; the three relapsing patients were given the LHRH analog and exhibited partial response to rectal examination (1 case) and to bone scan (2 cases). Pain disappeared completely in both the patients with bone metastases. Overall 3-year survival and disease-free survival rates were 97% and 79%, respectively. Disease-free survival was significantly related to cT (at 3 years: cT2: 100%; cT3: 81.2%; log rank test: 0.0081). Late toxicity was observed in two patients: rectal bleeding in one case and chronic diarrhea in the other. The combined protocol used in this study was feasible and well tolerated. Our results seem to confirm the promising preliminary results of Radiation Therapy Oncology Group 8610 study.

Adenocarcinoma↗
PubMed1996

Mutagenesis of endopolygalacturonase from Fusarium moniliforme: histidine residue 234 is critical for enzymatic and macerating activities and not for binding to polygalacturonase-inhibiting protein (PGIP).

The sequence encoding the endopolygalacturonase (PG) of Fusarium moniliforme was cloned into the E. coli/yeast shuttle vector Yepsec1 for secretion in yeast. The recombinant plasmid (pCC6) was used to transform Saccharomyces cerevisiae strain S150-2B; transformed yeast cells were able to secrete PG activity into the culture medium. The enzyme (wtY-PG) was purified, characterized, and shown to possess biochemical properties similar to those of the PG purified from F. moniliforme. The wtY-PG was able to macerate potato medullary tissue disks and was inhibited by the polygalacturonase-inhibiting protein (PGIP) purified from Phaseolus vulgaris. The sequence encoding PG in pCC6 was subjected to site-directed mutagenesis. Three residues in a region highly conserved in all the sequences known to encode PGs were separately mutated: His 234 was mutated into Lys (H 234-->K), and Ser 237 and Ser 240 into Gly (S 237-->G and S 240-->G). Each of the mutated sequences was used to transform S. cerevisiae and the mutated enzymes were purified and characterized. Replacement of His 234 with Lys abolished the enzymatic activity, confirming the biochemical evidence that a His residue is critical for enzyme activity. Replacement of either Ser 237 or Ser 240 with Gly reduced the enzymatic activity to 48% and 6%, respectively, of the wtY-PG. When applied to potato medullary tissue, F. moniliforme PG and wtY-PG caused comparable maceration, while the variant PGs exhibited a limited (S 234-->G and S 240-->G) or null (H 234-->K) macerating activity. The interaction between the variant enzymes and the P. vulgaris PGIP was investigated using a biosensor based on surface plasmon resonance (BIAlite). The three variant enzymes were still able to interact and bind to PGIP with association constants comparable to that of the wild type enzyme.

Amino Acid Sequence↗
PubMed1995

Prolonged continuous infusion of carboplatin and concomitant radiotherapy in advanced head and neck cancer. A phase I study.

A Phase I study on conventional radiotherapy and concomitant infusional chemotherapy with carboplatin (CBDCA) was initiated in order to evaluate the toxicity and feasibility of this combined treatment. Twenty-one patients with advanced head and neck carcinoma entered the study: 9 patients (Group A) received a 14-day infusion of 30 mg/m2 of CBDCA daily and 12 (Group B), a 21-day infusion beginning from the first day of radiotherapy. Total doses of 420 and 630 mg/m2 were given to group A and B, respectively. RT total dose ranged from 65 to 70 Gy with standard fractionation (180 cGy/5d/w). Major side effects observed were hematologic and mucosal. In group A grade 3 leukopenia was observed in five patients, grade 3 thrombocytopenia in one, and grade 3 mucositis in 2. In group B hematologic toxicity was severe: grade 3 and 4 leukopenia was seen in 4 and 3 patients, respectively; 3 patients had grade 3 and 2 patients grade 4 thrombocytopenia with a late appearance of nadir. Severe grade 3 mucositis was observed in 6 patients. Nineteen patients were evaluable for tumor response: 7/17 patients with stage III-IV disease achieved a CR and 8 a PR. According to our experience, prolonged infusion with CBDCA during conventional RT courses is feasible, though a certain level of toxicity remains. A 30 mg/m2 daily dose for 21-day infusion is associated with severe hematologic toxicity, while 14-day infusion can be considered the maximum tolerable dose. Whether CBDCA infusion has any advantage over bolus is yet to be confirmed.

Adult↗
PubMed1995

Congenital nystagmus: fine structure of human extraocular muscles.

The ultrastructure of the extraocular muscles of patients affected by congenital nystagmus is still to be defined. Specimens obtained from patients suffering from either oculomotor congenital nystagmus or nystagmus associated with strabismus were studied and compared with specimens obtained from patients enucleated for various pathologies but not affected by any oculomotor system disorder. The scleral myotendinous junction and the muscle body (venter) were examined. In both these areas, damaged muscle fibers were found. 'Mitochondrial cores' and concentric myofibrils characterized the extraocular muscles of the patients with oculomotor congenital nystagmus. In the extraocular muscles of the patients affected by nystagmus associated with strabismus we also found mitochondria with concentric cristae surrounding a highly electron-dense spherical body and numerous, large rods. In conclusion, these data indicate that both contractile and mitochondrial modifications might be signs of an altered muscle function and seem to indicate that oculomotor congenital nystagmus should be included among the list of oculomotor myopathies.

Adolescent↗
PubMed1994

Polygalacturonase-inhibiting protein accumulates in Phaseolus vulgaris L. in response to wounding, elicitors and fungal infection.

Polygalacturonase-inhibiting protein (PGIP) is a cell wall-associated protein that specifically binds to and inhibits the activity of fungal endopolygalacturonases. The Phaseolus vulgaris gene encoding PGIP has been cloned and characterized. Using a fragment of the cloned pgip gene as a probe in Northern blot experiments, it is demonstrated that the pgip mRNA accumulates in suspension-cultured bean cells following addition of elicitor-active oligogalacturonides or fungal glucan to the medium. Rabbit polyclonal antibodies specific for PGIP were generated against a synthetic peptide designed from the N-terminal region of PGIP; the antigenicity of the peptide was enhanced by coupling to KLH. Using the antibodies and the cloned pgip gene fragment as probes in Western and Northern blot experiments, respectively, it is shown that the levels of PGIP and its mRNA are increased in P. vulgaris hypocotyls in response to wounding or treatment with salicylic acid. Using gold-labeled goat-anti-rabbit secondary antibodies in EM studies, it has also been demonstrated that, in bean hypocotyls infected with Colletotrichum lindemuthianum, the level of PGIP preferentially increases in those cells immediately surrounding the infection site. The data support the hypothesis that synthesis of PGIP constitutes an active defense mechanism of plants that is elicited by signal molecules known to induce plant defense genes.

Amino Acid Sequence↗
PubMed1994

[A case of leishmaniasis in intensive care].

A case is presented of severe visceral leishmaniasis initially misdiagnosed owing to the old age of the patient and the contemporary presence of a carcinoma of the sigmoid. Admitted in ICU for severe post operative cardiorespiratory failure. During ICU stay the patients presented a bilateral pneumothorax and a long QT syndrome, presumably due to antimonials.

Aged↗
PubMed1993

Transthyretin-related TTR hereditary amyloidosis of the vitreous body. Clinical and molecular characterization in two Italian families.

Two unrelated Italian families affected by hereditary amyloidosis are described. Molecular genetic characterization demonstrated different mutations of the transthyretin gene. In all patients belonging to the TTR Ala 49 family the vitreous body, the heart and the peripheral nervous system were massively infiltrated by amyloid matter. In the TTR Pro 36 family vitreous opacities were the long-standing isolated manifestations of the disease. Two different patterns of vitreous deposits can be observed in these two families. The authors' data support the hypothesis that different pathological transthyretin proteins may have different affinity for the connective tissue in the vitreous.

Adult↗