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Biomedical subjects

L Federici

Publications and source records attributed to L Federici.

At least 19 recordsLinked to original sources
PubMed2006

[Update of clinical findings in cobalamin deficiency: personal data and review of the literature].

PURPOSE: During last decades, several progresses have been made in the diagnosis of cobalamin (vitamin B12) deficiency. Routine used of cobalamin standardized assays have potentially modified the frequency and the type of hematologic abnormalities. CURRENT KNOWLEDGE AND KEY POINTS: Current studies on cobalamin deficiency, including more precise definitions and the description of new etiologies of cobalamin deficiency in adults, as the food-cobalamin malabsorption syndrome, show that hematological abnormalities are generally incomplete compared to historical descriptions of megaloblastic anemia. Nevertheless, they include severe manifestations in 10% of the patients: pancytopenia, severe anemia (hemoglobin < 6 g/dl) or hemolytic anemia and pseudo thrombotic microangiopathy related to cobalamin deficiency. These studies also show the efficacy of new treatment modalities including oral cobalamin administration. PROSPECTS AND PROJECTS: Future studies will confirm these data with the routine use of the new cobalamin assay: holotranscobalamin and validate the usefulness of oral cobalamin therapy.

Administration, Oral↗
PubMed2006

A decision tree for genetic diagnosis of hereditary periodic fever in unselected patients.

BACKGROUND: The diagnostic value of molecular analysis of the familial Mediterranean fever (FMF) gene (Mediterranean fever (MEFV)) has been well established only in patients selected on the basis of ethnic background or clinical criteria. Genetic diagnosis for other hereditary periodic fever syndromes has been poorly evaluated. OBJECTIVE: To determine the diagnostic contribution of genetic tests for hereditary periodic syndromes in a large, unselected series of patients. METHODS: A retrospective study was conducted on 1941 patients referred to us for FMF genetic tests between 1997 and 2005. MEFV genotypes were compared with clinical data to appraise criteria for FMF diagnosis. Genetic tests for tumour necrosis factor receptor-associated periodic syndrome (TRAPS), hyperimmunoglobulinaemia D syndrome (HIDS) and cryopyrin-associated periodic syndromes (CAPS) were also reviewed. RESULTS: 71% of the 1574 patients with enough data had a clinical diagnosis of FMF according to the widely used Israeli criteria. Two MEFV mutations were found in only 409 patients of this subgroup (sensitivity = 37%) and in 15 (3.3%) of the patients with an improbable clinical diagnosis of FMF (specificity = 97%). Molecular diagnosis for alternate hereditary periodic syndromes was carried out in 456 of the patients having a non-conclusive FMF genetic test. A positive diagnosis was obtained in 31 of these patients (TRAPS (n = 19), HIDS (n = 4) and CAPS (n = 8)). CONCLUSIONS: First-line MEFV mutation screening in patients with clinically typical FMF may be appropriate only in particular areas. To optimise genetic diagnosis, we propose a decision tree, which, with the advice of an expert practitioner, could help redirect test indications towards non-FMF hereditary periodic syndromes.

Adolescent↗
PubMed2006

[Bilateral corneal endothelial decompensation after postsepticemia coma].

We report a case of unexplained bilateral corneal endothelial decompensation after a coma. A 71-year-old man with no medical history presented with bilateral endothelial decompensation that required penetrating keratoplasty of the left eye combined with cataract surgery. This coma was caused by septicemia originally due to staphylococcus infection following catheter placement in preparation for a CT scan. Visual acuity of the left eye was 20/400 and 20/100 in the right eye when the patient awoke from the coma. After examination, we noted only stromal thickening and Descemet membrane folds causing corneal edema predominating OS. The rest of the exam was normal. Six months after surgery, visual acuity improved to 20/25. The most probable physiopathological mechanism of this decompensation is an iatrogenic complication from drugs administered during the patient's stay in intensive care (oxacillin), but we cannot rule out direct aggression of a bacterium or its toxin or the decompensation of a preexisting pathology.

Aged↗
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↗
PubMed2001

Structural requirements of endopolygalacturonase for the interaction with PGIP (polygalacturonase-inhibiting protein).

To invade a plant tissue, phytopathogenic fungi produce several cell wall-degrading enzymes; among them, endopolygalacturonase (PG) catalyzes the fragmentation and solubilization of homogalacturonan. Polygalacturonase-inhibiting proteins (PGIPs), found in the cell wall of many plants, counteract fungal PGs by forming specific complexes with them. We report the crystal structure at 1.73 A resolution of PG from the phytopathogenic fungus Fusarium moniliforme (FmPG). The structure of FmPG was useful to study the mode of interaction of the enzyme with PGIP-2 from Phaseolus vulgaris. Several amino acids of FmPG were mutated, and their contribution to the formation of the complex with PGIP-2 was investigated by surface plasmon resonance. The residues Lys-269 and Arg-267, located inside the active site cleft, and His-188, at the edge of the active site cleft, are critical for the formation of the complex, which is consistent with the observed competitive inhibition of the enzyme played by PGIP-2. The replacement of His-188 with a proline or the insertion of a tryptophan after position 270, variations that both occur in plant PGs, interferes with the formation of the complex. We suggest that these variations are important structural requirements of plant PGs to prevent PGIP binding.

Base Sequence↗
PubMed2001

Secondary structure and post-translational modifications of the leucine-rich repeat protein PGIP (polygalacturonase-inhibiting protein) from Phaseolus vulgaris.

A detailed analysis of the secondary structure has been carried out on the polygalacturonase-inhibiting protein (PGIP) from Phaseolus vulgaris, a leucine-rich repeat (LRR) protein present in the cell wall of many plants. Far-UV CD and infrared spectroscopies coupled to constrained secondary structure prediction methods indicated the presence of 12 alpha- and 12 beta-segments, thus allowing a schematic representation of three domains of the protein, namely, the central LRR region and the two cysteine-rich flanking domains. Peptides from endoproteinase-degraded PGIP were analyzed by mass spectrometry, and four disulfide bonds were identified. Mass spectrometric analysis in combination with glycosidase treatments revealed two N-linked oligosaccharides located on Asn 64 and Asn 141. The main structure resembled the typical complex plant N-glycan consisting of a core pentasaccharide beta1,2-xylosylated, carrying an alpha1,3-fucose linked to the innermost N-acetylglucosamine and one outer arm N-acetylglucosamine residue. The schematic representation of PGIP structural domains is discussed in the framework of the structure and function of LRR proteins.

Amino Acid Sequence↗
PubMed2000

The crystal structure of saporin SO6 from Saponaria officinalis and its interaction with the ribosome.

The 2.0 A resolution crystal structure of the ribosome inactivating protein saporin (isoform 6) from seeds of Saponaria officinalis is presented. The fold typical of other plant toxins is conserved, despite some differences in the loop regions. The loop between strands beta7 and beta8 in the C-terminal region which spans over the active site cleft appears shorter in saporin, suggesting an easier access to the substrate. Furthermore we investigated the molecular interaction between saporin and the yeast ribosome by differential chemical modifications. A contact surface inside the C-terminal region of saporin has been identified. Structural comparison between saporin and other ribosome inactivating proteins reveals that this region is conserved and represents a peculiar motif involved in ribosome recognition.

Amino Acid Motifs↗
PubMed2000

Engineering His(E7) affects the control of heme reactivity in Aplysia limacina myoglobin.

Aplysia limacina myoglobin lacks the distal histidine (His (E7)) and displays a ligand stabilization mechanism based on Arg(E10). The double mutant Val(E7)His-Arg(E10)Thr has been prepared to engineer the role of His(E7), typical of mammalian myoglobins, in a different globin framework. The 2.0 A crystal structure of Val(E7)His-Arg(E10)Thr met-Mb mutant reveals that the His(E7) side chain points out of the distal pocket, providing an explanation for the observed failure to stabilize the Fe(II) bound oxygen in the ferrous myoglobin. Moreover, spectroscopic analysis together with kinetic data on azide binding to met-myoglobin are reported and discussed in terms of the presence of a water molecule at coordination distance from the heme iron.

Animals↗
PubMed2000

Crystallization and preliminary X-ray diffraction studies of a monooxygenase from Streptomyces coelicolor A3(2) involved in the biosynthesis of the polyketide actinorhodin.

The aromatic monooxygenase ActVA-Orf6 from Streptomyces coelicolor A3(2) that catalyses an unusual oxidation on the actinorhodin biosynthetic pathway has been crystallized. The crystals diffract to 1.73 A and belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 46.95, b = 59.29, c = 71.67 A. Solvent-content (44%) and self-rotation function calculations predict the presence of two molecules in the asymmetric unit. Structure determination should provide further insight into the enzyme mechanism and aid in the design of biosynthetic pathways to produce new polyketide natural products with novel functionality.

Anthraquinones↗
PubMed2000

Preliminary X-ray crystallographic analysis of a plant defence protein, the polygalacturonase-inhibiting protein from Phaseolus vulgaris.

A leucine-rich repeat plant protein involved in resistance to pathogens, a polygalacturonase-inhibiting protein (PGIP-1) from Phaseolus vulgaris, has been crystallized and preliminary X-ray characterization has been performed. The protein contains ten repeats of a short (24 amino-acid) leucine-rich repeat motif. Single crystals of the protein were grown from vapour-diffusion experiments using PEG 2K monomethylether as precipitant; these crystals diffract to at least 2.3 A resolution. The space group is P2(1), with two molecules of PGIP-1 in the asymmetric unit; the crystals contain approximately 38% solvent.

Amino Acid Sequence↗
PubMed1999

Crystallization and preliminary X-ray diffraction study of the endo-polygalacturonase from Fusarium moniliforme.

Endo-polygalacturonases catalyze the fragmentation and solubilization of the homogalacturonan of the plant cell wall. These enzymes are extracellularly targeted glycoproteins produced by a number of organisms such as fungi, bacteria and plants, and are involved in both pathological and physiological processes. Single crystals of the endo-polygalacturonase from the phytopathogenic fungus Fusarium moniliforme were obtained by the vapour-diffusion method at 294 K. The starting material as well as the crystal consist of three forms with different degrees of glycosylation. The crystals belong to the orthorhombic space group P212121 and diffract to 1.9 A resolution on a synchrotron-radiation source under cryocooling conditions.

Crystallization↗
PubMed1998

Crystallization and preliminary X-ray diffraction studies of DNA polymerase from the thermophilic archaeon Sulfolobus solfataricus.

The thermophilic and thermostable family B DNA polymerase from the archaeon Sulfolobus solfataricus (Mr of about 100 kDa) has been crystallized by the hanging-drop vapour-diffusion method at 294 K using ammonium sulfate as precipitant. The crystals belong to the monoclinic space group C2 with cell dimensions a = 187.4, b = 68.5, c = 125.8 A and beta = 107.8 degrees and diffract up to 2.7 A resolution on a rotating-anode X-ray source. Native data have been collected at 100 K. A heavy-atom derivative search is in progress.

Bacterial Proteins↗
PubMed1998

Crystallization and preliminary X-ray study of saporin, a ribosome-inactivating protein from Saponaria officinalis.

Single crystals of the protein saporin isolated from the seeds of S. officinalis have been grown by the vapor-diffusion method using ammonium sulfate as precipitant. The crystals are tetragonal, space group P4122 (P4322), with cell dimensions a = b = 67.53 and c = 119. 67 A, and diffract to 2.0 A resolution on a rotating-anode X-ray source. The asymmetric unit contains one molecule, corresponding to a volume of the asymmetric unit per unit mass (Vm) of 2.38 A3 Da-1.

Crystallization↗
PubMed1980

[Our experience with steroid anesthesia in orthopedic surgery].

Althesin (Glaxo) has been experimented clinically, on the basis of existing scientific literature on the drug, with a view to achieving a safer anaesthesiological technique, particularly as regards the elderly high risk patient, and so as to limit the use of muscle relaxants in conditions of this kind.

Adolescent↗