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Biomedical subjects

G Torri

Publications and source records attributed to G Torri.

At least 127 records · Page 7Linked to original sources
PubMed1995

Pharmacologic profile of a low-molecular-weight heparin depolymerized by gamma-irradiation.

Low molecular weight heparins (LMWHs) are considered to be the agent of choice for the prophylaxis of DVT in medical and surgical patients. Conventionally, these agents have been produced by fractionation of or by chemical or enzymatic depolymerization of native heparin. The fractionated heparin retains many of its biological properties such as AT III affinity and sulfate content gamma-irradiation (60Co) has been used to depolymerize GAGs (De Ambrosi et al. In: biomedical and Biotechnological Advances in Industrial Polysaccharides, pp. 45-53). This procedures has now been used for the preparation of LMWH derivatives of varying molecular weight. The current studies examine the biochemical and pharmacologic profile of one such gamma-irradiated depolymerized heparin. In standard clotting and amidolytic antiprotease assays (PT, APTT, AXa, Alla), gamma-irradiated depolymerized heparin produced equal or stronger activity when compared to a LMWH produced by nitrous acid depolymerization and retained the ability to active AT III and HCHII. Initial results indicate that LMWHs produced by gamma-irradiation exhibit comparable antithrombotic actions to those produced by chemical depolymerization when measured in animal models of thrombosis. gamma-Irradiation may be a useful method for the production of LMWHs.

Animals↗
PubMed1995

Regional cerebral metabolism of glucose in comatose and vegetative state patients.

Regional cerebral metabolism of glucose (rCMRglu) was evaluated in patients who were in a coma and vegetative state to determine the level of brain function during these conditions. rCMRglu was measured in 17 discrete brain regions with (/-) [18F] -fluoro-2-deoxy-D-glucose (FDG) and positrn emission tomography (PET) in 15 patients with ;brain pathology subsequent to cardiorespiratory arrest (CA), head trauma (HT), or brain ischemia (BI) resulting from cerebrovascular accident or brain surgery. Five comatose patients (Coma group, n = 5), and 10 vegetative state patients (VS, patients awake but not aware) were studied. The VA patients were subdivided, according to the length of their VS condition, into a VS group (n = 6, < 3 months if CA or BI patients, or < 12 months if HT patients) and a persistent vegetative state group (PVS, n = 4, > 3 months if CA or BI patients of > 12 months if HT patients.) Ten normal age-matched subjects served as control. Global CMRglu was 6.72 +/- 0.93 (+/-SD) mg/100 g/min in control subjects. It was significantly (p < - 0.001) reduced to 3.70 +/- 61 in coma, to 3.45 +/- in VS, and to 2.33 +/- 0.34 mg/100 g/min in PVS patients. rCMRglu was significantly reduced (p < - 01001) from control values in all the 17 structures surveyed in every patient. In the Coma and VS groups, there was an overlapping of rCMRglu in the majority of the brain structures. (ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Quantitation of dermatan sulfate active site for heparin cofactor II by 1H nuclear magnetic resonance spectroscopy.

The sequence (IdoA2SO3-GalNAc4SO3)n contributes to the HCII-mediated inhibition of thrombin by dermatan sulfate (DS). This sequence clearly results from the 13C NMR spectrum and can be quantified by the signal C1-H of IdoA2SO3 in the 1H NMR spectrum. A linear correlation has been found between the content in the disulfated disaccharide delta Di-2,4diS obtained by enzymatic demolition with ABC lyase, the percentage content in IdoA2SO3 quantified by 1H NMR, and the HCII-mediated activity of dermatan sulfates from beef mucosa and pig skin. DSs have been obtained also from pig mucosa and contain an amount, not negligible, of delta Di-4, 6diS. This disulfate disaccharide contributes to the activity expressed by the IdoA2SO3-GalNAc4SO3 sequence. The analytical techniques HPLC and 1H NMR, applied to the currently performed analyses of DS, are described and discussed.

Binding Sites↗
PubMed1994

Heparin-like compounds prepared by chemical modification of capsular polysaccharide from E. coli K5.

O-Sulfation of sulfaminoheparosan SAH, a glycosaminoglucuronan with the structure-->4)-beta-D-GlcA(1-->4)-beta-D-GlcNSO3(-)-(1-->, obtained by N-deacetylation and N-sulfation of the capsular polysaccharide from E. coli K5, was investigated in order to characterize the sulfation pattern eliciting heparin-like activities. SAH was reacted (as the tributylammonium salt in N,N-dimethylformamide) with pyridine-sulfur trioxide under systematically different experimental conditions. The structure of O-sulfated products (SAHS), as determined by mono- and two-dimensional 1H and 13C NMR, varied with variation of reaction parameters. Sulfation of SAH preferentially occurred at O-6 of the GlcNSO3- residues. Further sulfation occurred either at O-3 or at O-2 of the GlcA residues, depending on the experimental conditions. Products with significantly high affinity for antithrombin and antifactor Xa activity were obtained under well-defined conditions. These products contained the trisulfated aminosugar GlcNSO3-3,6SO3-, which is a marker component of the pentasaccharide sequence through which heparin binds to antithrombin.

Carbohydrate Conformation↗
PubMed1994

Synthesis of a N'-alkylamine anticoagulant active low-molecular-mass heparin for radioactive and fluorescent labeling.

Heparin plays an important role in anticoagulation and several other biological processes. Cleavage of heparin by nitrous acid results in a reactive 2,5-anhydromannose (Am) which can be used to selectively insert primary and secondary amines by reductive amination. Low-molecular-mass heparin (LMMH) was bound to 4-(2-aminoethylphenol) as shown by nuclear magnetic resonance spectroscopy (NMR), high-performance size-exclusion chromatography (HPSEC), polyacrylamide gel electrophoresis (PAGE), and ultraviolet/visible (uv/vis) spectroscopy. 1H NMR spectra revealed an average sequence of (IdoA2SO3-GlcNSO36SO3)9-IdoA2SO3-Am-tyramine and a 50% binding rate of tyramine to LMMH. LMMH-Tyr had an anticoagulant activity of 108 antifactor Xa activity (aXa) U/mg and 42 antifactor IIa activity (aIIa) U/mg. The compound was neutralized by protamine. The N-alkylamine derivative was adopted to label LMMH with iodine-125 by oxidation with chloramine T. Fluorescein-5-isothiocyanate (Fitc) was used to label LMMH-Tyr with fluorescence. NMR, HPSEC, PAGE, and uv/vis spectroscopy demonstrated the binding of Fitc to LMMH-Tyr. 1H NMR spectra indicated that about 80% of the LMMH-Tyr was labeled at the secondary amino group. The fluorescent compound exhibited 70 aXa and 5 aIIa U/mg and was neutralized by protamine. The selectively bound labeled heparin derivatives are "endpoint attached" and have intact anticoagulant activity.

Anticoagulants↗
PubMed1994

Preparation and characterization of deuterium-labeled glycosaminoglycans.

Heparin, NAcHep, DS, and CS were labeled with deuterium by N-reacetylating, with the deuterated acetic anhydride (CD3CO)2O, GAGs previously N-deacetylated (by hydrazinolysis) to the desired extent. Degrees of deuteration of the present preparations, as determined by 2H- and 1H-NMR were 15%, 51%, 49%, and 79% for heparin, NAcHep, DS, and CS, respectively. The NMR analysis (including the 13C spectra) of the labeled products indicated that deuterium labeling did not involve any substantial modification of the GAG structures. Also NMR signals associated with specific sequences of heparin for antithrombin and of DS for heparin cofactor II were essentially the same in the unlabeled and in the deuterated GAGs. The substantial retention of the original structure was confirmed by data on the degree of sulfation (by conductimetry) and on the electrophoretic mobility in acid buffer. On the other hand, HPLC/SEC data indicated some depolymerization of heparin and DS in the N-deacetylation step of the labeling reactions. HPLC/MS spectrometry permitted a clear identification of disaccharide and tetrasaccharide fragments obtained from deuterated GAGs by enzymic (heparinase, chondroitinase ABC) or chemical depolymerization (deaminative cleavage, Smith degradation), opening new prospects for studies of human pharmacokinetics, with differentiation of exogenous from endogenous GAGs.

Acetic Anhydrides↗
PubMed1994

Semisynthesis and analysis of lipophilically modified unfractionated and low molecular mass heparins.

Unfractionated heparin and LMMH were substituted with different lipophilic organic compounds. Specifically endpoint attached (LMMH-tyramine and LMMH-tyramine-FITC) and nonspecifically substituted heparins (acylated heparins, and LMMH-biotin and LMMH-cholesterol hemisuccinate) were obtained. The lipophilically substituted heparins were analysed by HPSEC and showed different retention times, high peak purity, different UV/VIS absorbances, and areas under the absorbance time curve. The determination of the average molecular mass Mn, Mm, and Mz and the polydispersity P was performed by PAGE. The substituted heparins showed an increase in their molecular mass Mm, ranging from 2.9 to 129.7% unfractionated heparin and 3.9 to 224.0% (LMMH) compared with the parent compounds (unfractionated heparin and LMMH). The anticoagulant activity was measured by anti-Factor Xa. Lipophilically modified heparin had an aXa activity ranging from 52 to 168 U/mg (unfractionated) and 60 to 108 U/mg (LMMH) and antithrombin activity ranging from 31 to 270 U/mg (unfractionated) and 5 to 15 U/mg (LMMH). The thrombin generation inhibition assay demonstrated an effective anticoagulant potency of the modified compounds. They were neutralized by different amounts (1.1 to 4.1, w/w) of protamin. 1H NMR spectroscopy revealed the specific endpoint attachment of tyramine to LMMH and FITC to LMMH-tyramine. The lipophilically modified heparins showed intact anticoagulant properties and are now used for pharmacokinetic investigations.

Acylation↗
PubMed1994

Isolation of new genes in distal Xq28: transcriptional map and identification of a human homologue of the ARD1 N-acetyl transferase of Saccharomyces cerevisiae.

In this paper, we describe the physical and transcriptional organization of a region of 140 kb in Xq28, 5' to the L1CAM gene. By isolation and mapping of CpG islands to the physical map of the region, isolation of cDNAs, determination of partial nucleotide sequences and study of the pattern of expression and of the orientation of the transcripts identified we have established a transcriptional map of this region. In this map, previously identified genes (L1CAM, V2R, HCF1 and RnBP) have been positioned as well as 3 new genes. All genes in the region are rather small, ranging in size from 2 to 30 kb, and very close to one another. With the exception of the V2R gene, they are housekeeping, have a CpG island at their 5' end and the same orientation of transcription. This kind of organization is consistent with the one previously described for the more distal portion of Xq28, between the Color Vision (CV) and the G6PD genes and indicates that genes with housekeeping and tissue specific pattern of expression are interspersed in the genome but they are probably found in different 'transcriptional domains'. Among the new genes, TE2 demonstrated 40% identity with the protein N-acetyl transferase ARD1 of S. cerevisiae: TE2 may be the human homologue of the S. cerevisiae gene.

Acetyltransferases↗
PubMed1994

The occurrence of glycolipids in the lichen Ramalina celastri.

We report for the first time the detection of glycolipids in a lichen. Three glycolipids were extracted from Ramalina celastri and their carbohydrates were determined. The main component was O-alpha-D-galactopyranosyl-(1-->6)-O-beta-D-galactopyranosyl-(1-->1)-D- glyceritol, esterified with long-chain fatty acids, some of which were unsaturated.

Glycolipids↗
PubMed1994

[Respiratory exchange during laparoscopic and laparotomic cholecystectomy].

The utility of laparoscopic cholecystectomy in reducing postoperative pain and patient's hospital discharge is already known. Nevertheless peritoneal gas insufflation required by surgical procedure can modify respiratory homeostasis during general anesthesia. The aim of this study was to evaluate the effect of laparoscopic cholecystectomy on pulmonary dead spaces and alveolar gas exchange during inhalation anesthesia compared with traditional laparotomic cholecystectomy. With the approval of Hospital Ethical Committee, thirty-one patients undergoing isoflurane general anesthesia for laparoscopic (CL-S, n = 16) and open (CL-T, n = 15) cholecystectomy were prospectively evaluated in order to asses modifications in physiological (VDphy/VT), anatomical (VDan/VT) and alveolar (VDalv/VT) dead space to tidal volume ratio, arterial to end-tidal carbon dioxide partial pressure difference [P(a-Et)CO2] and alveolar to arterial oxygen partial pressure difference (A-aDO2). Patients, 21-64 years-old, ASA I-II, had no cardiopulmonary diseases. The CL-S group required peritoneal insufflation of carbon dioxide with an intraabdominal pressure (IAP) of about 10-14 mmHg and antitrendelenburg positioning (15-20 degree). Expired gas measurements and arterial blood gas sample for pulmonary dead spaces and arterial to alveolar CO2 and O2 gradient calculation were performed 20 min after a steady state condition. VDphy/VT, VDalv/VT, P(a-Et)CO2 and A-aDO2 increased significantly in the CL-S compared to the CL-T group (p < 0.05). No differences were found in the VDan/VT. These results can be explained by analteration of the ventilation to perfusion ratio (VA/Q) with an increase of high VA/Q regions due to the antitrendelenburg positioning with a redistribution of blood flow towards basal zones.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Streptococcus pyogenes toxic shock. A clinical case].

Toxic shock-like syndrome (TSLS) due to Streptococcus pyogenes has been recently reported in both children and adults. This syndrome is characterized by hypotension or shock, fever, multiorgan system involvement and death in 30 to 60% of patients. This syndrome closely resembles the more frequent staphylococcal TSLS. Only one case of TSLS caused by streptococcus has been reported, up to now, in our Country. We describe a second case of fatal streptococcus pyogenes TSLS in a 64-year-old man, in which the site of infection was in the soft tissues. The illness was characterized by rapid progression of shock, erythematous rash, multisystem organ involvement and finally death. Clinicians must be aware of the presentation of this disease as its incidence appears to be increasing.

Humans↗
PubMed1993

Structure and contribution to the heparin cofactor II-mediated inhibition of thrombin of naturally oversulphated sequences of dermatan sulphate.

Dermatan sulphate (DS) obtained from bovine and pig mucosa and pig skin, and charge-enriched fractions of a selected DS preparation, were characterized in terms of charge density, M(r) and disaccharide composition of chondroitin ABC lyase digests, and by 13C-n.m.r. spectroscopy. Besides the major IdoA-GalNAc4SO3 sequences, all DS preparations contain about 10% disulphated disaccharide sequences (mostly IdoA2SO3-GalNAc4SO3, with minor amounts of IdoA-GalNAc4,6SO3). DS fragments (prepared by radical-catalysed depolymerization of DS and retaining the internal structure of the parent polysaccharide) as well as Smith degraded fragments [SD-DS, obtained by controlled degradation of periodate-oxidized and borohydride-reduced DS (RO-DS)] with the general structure GalNAc4SO3(IdoA2SO3-GalNAc4SO3)n-R (where R is the remnant of a glycol-split uronic acid, and n = 2-3 and 3-4) were characterized by one- and two-dimensional 1H-n.m.r., 13C-n.m.r. and disaccharide composition analysis. In accordance with previous findings [Maimone and Tollefsen (1990) J. Biol. Chem. 265, 18263-18271], only fragments with n > or = 3 significantly enhance the heparin cofactor II-mediated inhibition of thrombin. In natural DS preparations and their fractions, this activity (as well as the antithrombotic activity in an animal model) appears to require IdoA2SO3-containing sequences. The heparin cofactor II activity of DS, RO-DS and SD-DS fragments decreases with decreasing M(r). However, RO-DS fragments are more active than DS fragments of similar M(r), probably because of the extra flexibility endowed by glycol-split IdoA residues.

Animals↗
PubMed1993

Transcriptional organization of a 450-kb region of the human X chromosome in Xq28.

In this paper, we report the transcriptional organization of a 450-kb gene cluster in Xq28, flanked by the glucose-6-phosphate dehydrogenase and the color vision genes. CpG islands previously identified and mapped to distal Xq28 have helped in construction of a continuous contig of cosmids and in identification of cDNAs corresponding to eight transcripts. Thirteen to 16 small genes with CpG islands are clustered in a region of 250-300 kb. Many are highly expressed in muscle or brain and may be the genes responsible for muscle or neurological disorders mapped to distal Xq28. Our analysis indicates that, in this region of the genome, genes not related in sequence are organized in transcriptional domains of 100 kb and that this organization may be important for establishing and regulating gene expression in relation to tissue distribution and X chromosome inactivation.

Base Sequence↗
PubMed1993

Characterization of the chemical structure of sulphated glycosaminoglycans after enzymatic digestion. Application of liquid chromatography-mass spectrometry with an atmospheric pressure interface.

Pneumatically assisted electrospray was demonstrated to be a powerful ionization source for the analysis of oligosaccharides. A mass spectrometer was interfaced to an HPLC system, using this interface, to determine oligosaccharides from the enzymatic digestion of heparin separated on a reversed-phase column. To set up the technique, and particularly to clarify the ionization process, purified disaccharides, from enzymatic digestion of chondroitin sulphates, were measured. The use of a suitable counter ion in the mobile phase, tetrapropylammonium (TPA), to optimize the HPLC separation, gave, with sulphated di- and oligosaccharides, adducts [M + nTPA - (n + m)H]m-, which were unexpectedly stable to fragmentation; molecular ions [M - (n + 1)H]n-, in the presence of the counter ion, were observed only with desulphated or monosulphated disaccharides. The stability of the adducts and the use of a deuterated ion-pair reagent permitted an exact evaluation of the molecular masses of disaccharides and oligosaccharides of unknown structure. Spectra obtained in the absence of the counter ion contained singly or multiply charged molecular ions and fragmentation ions mainly from loss of the sulphate groups; under these ionization conditions the exact mass determination and interpretation of the spectra were difficult. After removal of the counter ion, tandem mass spectra could be obtained with some interesting data for the characterization of these molecules. Complete spectral analyses were performed with amounts of samples of 50 micrograms but, using microbore columns, one twentieth of this amount may give good spectra.

Atmospheric Pressure↗
PubMed1993

A comparative study of low-density lipoprotein interaction with glycosaminoglycans.

The association between low-density lipoprotein (LDL) and a series of well characterized dermatan and chondroitin sulfates has been investigated by means of the fluorescence anisotropy technique with competition experiments using a fluorescein-labeled high LDL-affinity heparin fraction as a reference. Preparations of glycosaminoglycan (GAG) with sulfation degrees varying over a wide range, as obtained by fractionation or by chemical modification, were chosen for this study. The influence of chain length, which had been found sizeable in a former study of heparin affinity for LDL, was taken into account with an empirical correction of dissociation constants. After this correction, a linear relationship was found between the logarithm of dissociation constants and the number of sulfate groups per disaccharide unit, ns, both for dermatan and chondroitin sulfates, and for heparins. At comparable ns values, however, dermatan sulfates and heparins, which contain L-iduronic acid in their backbone, show higher LDL-affinity than chondroitin sulfates, which contain only D-glucuronic acid. Though confirming a non-specific, predominantly electrostatic interaction between GAGs and LDL, these results indicate modulation of LDL affinity by the polysaccharide backbone.

Binding Sites↗