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G Serafini

Publications and source records attributed to G Serafini.

At least 37 records · Page 2Linked to original sources
PubMed1998

Expression, purification, and characterization of a recombinant erythroid-specific hexokinase isozyme.

Hexokinase type I (HK I; ATP: D-hexose 6-phosphotransferase, EC 2.7.1.1), the predominant glucose-phosphorylating enzyme in red blood cells, exists in human erythrocytes in multiple molecular forms that differ in isoelectric point and are separable by ion-exchange chromatography. The major forms, designated HK Ia, Ib and Ic, have similar kinetic properties but are characterized by different age-dependent decay and different intracellular distribution in reticulocytes. HK Ib, which elutes between HK I and HK II in the DEAE ion-exchange chromatography, appears to be unique to RBCs and different from any other hexokinase isozyme previously described. Indeed, Murakami and Piomelli recently reported the presence of a specific HK isozyme (named HKr) expressed in K562 cells and in human reticulocytes and, moreover, the resolution of the human HK I gene structure provided the direct evidence of an erythroid-specific exon 1. To further investigate the microheterogeneity of HK I in human RBCs we established a prokaryotic expression system for the HKr isozyme, using the pET plasmid, inducible with IPTG. The recombinant HKr, expressed in bacterial cells as a catalytically active enzyme, was purified to homogeneity by a combination of DEAE ionexchange chromatography followed by hydrophobic interaction chromatography and dye-ligand affinity chromatography. The kinetic and chromatographic properties of the homogeneous recombinant HKr suggest that this erythroid-specific HK isozyme in fact corresponds to the HK isoform previously described in human RBCs and referred to as HK Ib.

Erythrocytes↗
PubMed1998

Role of surgical techniques and operative findings in cranial and cervical nerve injuries during carotid endarterectomy.

OBJECTIVE: To establish the incidence of cranial and cervical nerve injuries during CEA and their relationship to different surgical techniques and operative findings. DESIGN: A prospective study. PATIENTS AND METHODS: From January 1994 to April 1995, 187 consecutive patients undergoing 190 CEAs were evaluated. Pre- and postoperative cranial and cervical nerve assessments were carried out by a single otolaryngologist, blinded to the operative technique and findings. Deficits lasting more than 12 months were defined as permanent. Logistic regression analysis was performed to evaluate the influence of surgical technique, type of anaesthesia, neck haematoma, and plaque extension on the onset of nerve injuries. RESULTS: Postoperatively, nerve lesions were identified in 51 CEAs (27%) and non-neurological injuries (hemilaryngeal ecchymosis or oedema) causing postoperative dysphonia were present in 80 CEAs (42%). All non-neurological injuries were transient and 98% disappeared within 1 month of surgery. Thirteen (7%) nerve lesions were permanent, but none were disabling. Vagus nerve lesions were significantly associated with long (> 2 cm) carotid plaque (OR = 3.5; CI 1.09-12.37; p = 0.03). Cervical branch lesions were associated with the presence of neck haematoma (OR = 1.9; CI 0.7-4.7; p = 0.05). The incidence of single cranial nerve injuries was higher in patch (OR = 2.7) and eversion (OR = 1.9) procedures than in primary closure. Multiple deficits (2 or more) were most frequent in eversion CEAs (OR = 2.8) and in cases complicated by neck haematoma (OR = 3.8). CONCLUSIONS: Cranial and cervical nerve lesions during CEA are common. However, our data showed that the majority of local complications are related to transient hemilaryngeal ecchymosis or oedema and, when permanent, are neither clinically relevant nor disabling at 1 year of follow up. Carotid plaque extension and neck haematoma appear to increase the incidence of cranial and cervical nerve lesions during CEA.

Adult↗
PubMed1998

Enzymatic properties of overexpressed human hexokinase fragments.

Full-length hexokinase (HK; ATP: D-hexose 6-phosphotransferase, EC 2.7.1.1), a truncate form of the enzyme lacking the first 11 amino acids (HK-11aa) and the 50 kDa C-terminal half ('mini'-HK) containing the catalytic domain, were overexpressed and purified to homogeneity to investigate the influence of the N-terminal region of human hexokinase type I (HK) on its regulatory properties. All forms of the enzyme are catalytically active with the HK-11aa being the most active. All the forms of HK showed the same affinity for glucose and MgATP and were also inhibited by glucose 6-phosphate (Glc 6-P) competitively vs. MgATP with similar Kis (28.5-37 microM). Glucose 1,6-bisphosphate (Glc 1,6-P2) was also a strong inhibitor of all HKs without significant differences among the different truncate forms of the enzyme (Kis 49.5-59 microM). At low concentrations (0-3 mM), Pi was able to reverse the sugar phosphate inhibition of the full-length HK and HK-11aa but not of the 'mini'-HK. In contrast, at high concentrations Pi was an inhibitor of all the hexokinases investigated. These findings confirm that Pi has a low affinity binding site on the C-terminal of HK while counteracts glucose 6-phosphate inhibition by binding to or requiring the N-terminal half of the enzyme. The first 11 N-terminal amino acids influence the specific activity of HK but are unable to affect the kinetic properties investigated.

Dose-Response Relationship, Drug↗
PubMed1998

[Sudden idiopathic hearing loss. Case reports in the course of ten years].

The authors present a retrospective case study of 132 subjects with sudden-onset hearing loss who had been observed during the course of 10 years. The results were compared with those available in the literature. These patients were divided into two subgroups based on age: over or under 40. The hearing loss was divided into 4 subgroups according to audiogram morphology. Then the presence, and entity, of any recovery in hearing was evaluated. There was no preference for sex while the greatest incidence was found in the VI and VII decade of life. The audiohistograms obtained when the patients were admitted to the hospital and 2 months later indicated an improvement in the hearing threshold localized above-all in the medium-low frequencies. This confirms a better evolution in those forms localized in the apex of the cochlea. The threshold of 60 dB HL is the dividing line between a totally favorable prognosis and a partially or totally unfavorable prognosis. This indirectly confirms that the intensity of the initial hearing damage is an important prognostic factor. From the morphological point of view the forms with the best evolution appear to be those with a flat or rising morphology. The forms with descending morphology do not present a favorable evolution although those with a threshold around 8000 Hz are worse than those with a threshold of 4000 Hz. As regards age no significant differences were found in the evolution of hearing loss between subjects under and over 40. In conclusion, the essential characteristics of sudden-onset hearing loss are as yet poorly defined. There are so many variables affecting the onset and evolution of hearing loss that it proves impossible to perform any statistically valid analysis which includes them all. To date the elements able to provide some degree of prognostic prediction are the audiogram morphology and the entity of the initial hearing loss.

Adolescent↗
PubMed1998

ABR and HIV-induced impairment of the central nervous system.

This in vivo study used Auditory Brainstem Responses (ABR) to evaluate nerve transmission integrity in the course of HIV infection. 48 normoacoustic HIV+ patients (40 men, 8 women) and 10 healthy age, sex and risk-factor matched controls underwent Brainstem Evoked Auditory potentials using a standard technique. Potentials were tested at cadences of 11 and 51 stimuli per second. ANOVA and Student's T test were used for inter Center for disease Control (CDC) classes and CDC classes vs control analysis of the values of the principal wave latencies (I, III, V) and interpeak intervals (I-III, III-V, I-V). Significant impairments in nerve transmission, shown best at the 51 pps cadence, were present from the earliest stages of HIV infection and worsened as the disease progressed. These results suggest that the upper part of the brainstem may be the main target of involvement in the tract being tested. Since electrophysiological tests allow detection of nervous dysfunction in subjects while still asymptomatic, these procedures could be usefully employed in order to better define the real onset of brain damage in HIV-1 seropositive patients and monitor the speed with which these lesions evolve.

Adult↗
PubMed1997

Molecular bases of hexokinase deficiency.

Hexokinase (ATP: D-hexose 6-phosphotransferase, EC 2.7.1.1; HK) deficiency is a rare disease where the predominant clinical effect is nonspherocytic hemolytic anemia. We have previously shown that the only patient for which hexokinase deficiency has been so far investigated at molecular level is a double heterozygote carrying a T1667 --> C substitution on one HK type I allele and a 96 bp deletion (concerning nucleotides 577 to 672 in the HK cDNA sequence) in the other allele. To investigate whether these mutations found in the patient with the hexokinase variant referred to as 'HK-Melzo' could be associated with hexokinase deficiency, we have expressed in E. coli the wild-type human hexokinase type I and two different mutants carrying the T --> C nucleotide substitution at position 1667 and the nt 577-672 deletion, respectively. Wild-type human recombinant hexokinase is expressed in bacterial cells as a soluble catalytically active enzyme that, upon purification to homogeneity, exhibited the same kinetic properties of human placenta hexokinase type I. Both mutant hexokinases were also expressed as soluble recombinant proteins under the same conditions, but they showed an impaired catalytic activity with respect to the wild-type enzyme. In particular, the T1667 --> C substitution, causing the amino acid change from Leu529 to Ser, is responsible for the complete loss of the hexokinase catalytic activity, while the 96 bp deletion causes a drastic reduction of the hexokinase activity. Taken together, both mutations explain the hexokinase deficiency found in the patient with the 'HK-Melzo' variant.

Amino Acid Sequence↗
PubMed1997

Isometric handgrip exercise increases endothelin-1 plasma levels in patients with chronic congestive heart failure.

This study demonstrated an immediate and short-lasting endothelin-1 release in the circulation of patients with severe chronic congestive heart failure during isometric handgrip exercise, but not in normal subjects. Our data suggest that endothelin-1 levels may increase transiently during daily physical activity, thus contributing to progressive deterioration of left ventricular function.

Adult↗
PubMed1997

[The role of MRI in the valuation of disorders involving the bone marrow].

MR is the most accurate imaging technique in bone marrow evaluation since it allows to recognize and distinguish its red and yellow components. MR shows high sensitivity but low specificity. At present, its role in bone marrow diseases evaluation is that of depicting the extent of the disease process and monitoring the effects of treatment.

Bone Marrow↗
PubMed1997

[Sensitivity of spiral volumetric TC in the diagnosis of hepatic metastases: advantages of the dual phase technic].

In this report the diagnostic possibilities of volumetric Spiral CT in hepatic metastases detection are discussed. Spiral CT presents numerous advantages when compared to the conventional one; these increase its sensitivity in hepatic metastases diagnosis of approximately 10% (Conventional CT sensitivity 80-85%; Spiral CT sensitivity 90-95%). "Dual phase" technique allows hypervascular metastases diagnosis, often isodense during portal venous phase, hence not detectable with conventional CT. Nonetheless, helical CT for hepatic metastases detection is not yet common, due to high exams costs and more often due to the limited availability of equipment.

Humans↗
PubMed1996

High-level expression and purification of a human "mini"-hexokinase.

Human hexokinase type I is a 100-kDa enzyme with the catalytic site located in the C-terminal domain. We had previously expressed this domain in Escherichia coli, however only a small amount of the recombinant enzyme was catalytically active. To overcome this problem we have now expressed the "mini"-hexokinase using the pET expression system. An average of 1000 U of enzyme per liter of culture was obtained. The recombinant enzyme was purified to homogeneity by a combination of ion-exchange chromatography, affinity chromatography, and dye-ligand chromatography. The enzyme was unstable under ultrafiltration; thus, a multicolumn purification procedure was developed in order to avoid the ultrafiltration steps. The recombinant "mini"-hexokinase was found to have the same kinetic properties as the entire enzyme. Using the method described, the enzyme can be obtained in sufficient quantities for biophysical and biochemical investigations.

Blotting, Western↗
PubMed1996

Benign paroxysmal positional vertigo of posterior semicircular canal: results in 160 cases treated with Semont's maneuver.

One hundred sixty patients affected by benign paroxysmal positional vertigo of the posterior semicircular canal were treated with Semont's maneuver. Complete recovery after only one session was achieved in more than 50% of cases. After a maximum of five sessions, almost all patients had recovered; only 8 needed another kind of rehabilitation. No drug therapy was required for any patient.

Female↗
PubMed1996

Lipomatous tumors of the uterus: ultrasonographic findings in 11 cases.

We reviewed the ultrasonographic findings in eight patients with 11 lipomatous uterine tumors studied with transabdominal (eight cases) and transvaginal (six cases) techniques. A transvaginal color Doppler study was obtained in five patients. Two patients had more than one nodule (two and three uterine nodules, respectively). All lipomatous tumors had regular margins and were hyperechoic. Transvaginal sonography allowed the identification of one small previously undetected tumor but was not able to image the entire extent of two large lipomatous masses. In one case, it helped to establish the actual uterine origin of an eccentric pelvic mass. Color Doppler sonography showed complete absence of flow in all tumors examined. We believe that lipomatous tumors of the uterus can be diagnosed with a high degree of certainty by ultrasonography if a homogeneously hyperechoic avascular mass can be clearly identified to be of uterine origin.

Adult↗
PubMed1996

High resolution sonography of the flexor tendons in trigger fingers.

A sonographic study was conducted to analyze changes of the flexor tendons in patients with trigger fingers. We evaluated thickness and echotexture of the flexor tendons of the fingers in 54 patients with 66 symptomatic digits using 10 and 13 MHz "small parts" transducers; the results were compared with those observed in 20 normal controls. Images were obtained on the volar surface of the hand, at the head of metacarpals, and at the base of first phalanx, where the first annular pulley of the digital canal is located and where the changes occurring during passive assisted extension of the fingers were evaluated. Normal tendons were 2.9 to 4.4 mm thick (mean, 3.71 +/- 0.46) and had fibrillar echotexture. Patients had tendons ranging from 3.8 to 6.7 mm (mean, 5.41 +/- 0.94); the difference from controls was highly significant (P < 0.001). A cyst was attached on the volar surface of the involved tendons in 15 cases. Diffuse thickening of the synovial sheath was present in 20 tendons, whereas 17 tendons had irregular internal echotexture. Extension movements caused changes in shape of both cysts and peritendinous envelopes. In conclusion, sonography seems able to identify a variety of pathologic changes affecting tendons in these patients and may help both to explain the pathophysiology of their clinical situation and guide therapeutic decisions.

Adolescent↗
PubMed1996

Ultrasonography of peripheral nerves.

During sonographic examination of the extremities using high frequency "small-parts" equipment, peripheral nerves may be identified in virtually all patients. Peripheral nerves have a typical ultrasonographic pattern that correlates well with histologic structure and facilitates differentiation between nerves and tendons. The ability of this technique to depict peripheral nerves makes it possible, in many instances, to study nerve abnormalities in trauma, entrapment syndromes and tumors. Ultrasound can enable differentiation of an endoneural from an extraneural space-occupying lesion and evaluation of the extent and consistency of the lesion, as well as the integrity and dynamic behavior of the nerve involved at follow-up study. The purpose of this review article is to describe the normal ultrasonographic appearance of peripheral nerves and to discuss the potential role of this technique to image nerve lesions noninvasively. A series of paradigmatic ultrasound images of diverse pathologic processes involving peripheral nerves is presented. Although the ultrasound study of peripheral nerves remains in its infancy, with further refinement of ultrasound technology and a more precise knowledge of the ultrasound appearance of the extremities we may be optimistic to the future impact of this technique on diagnosis, treatment and prognosis in patients clinically suspected to have a nerve lesion.

Humans↗
PubMed1996

[Artificial ventilation in children during anesthesia].

The authors describe the advantages and disadvantages, the indications and benefits on gas exchange as a result of mechanical ventilation during anaesthesia. The two models of ventilation most commonly used have been analyzed: pressure ventilators and volume preset ventilators. The former are used only in cases of short-term anaesthesia or when volume ventilators are not available. Both the most appropriate settings and ventilatory modes have been discussed regarding different paediatric ages. Particular attention has been given to the oxygen concentration in the ventilated gases (oxygen toxicity > 40%) and to barotrauma connected with high peak pressure (> 30 cm H2O). The authors suggest the type and caliber of endotracheal tube and the tidal volume for paediatric ages.

Anesthesia, General↗
PubMed1995

Compliance to compulsory vaccination: strategies and results.

This report is devoted to analyze the effect that compulsory vaccination has on the compliance of the population, compared with the results obtained by massive campaigns for optional vaccinations. The implementation of a specific software for the management of individual schedules helps to reach a substantial complete coverage of the individuals for the first ones, while improving but incomplete results regard the vaccines against pertussis and measles-mumps-rubella, optional in Italy. The optimization of data management at the local health unit level improves the quality and the satisfaction of the work performed by the personnel, but has a limited effect on the already nearly complete coverage for the compulsory immunizations. The mounting percentage of children immunized with optional vaccines can be explained both by the massive campaigns of information conducted in recent years and by the better tracking of individual immunization schedules.

Humans↗