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Biomedical subjects

G Giordano

Publications and source records attributed to G Giordano.

At least 37 records · Page 2Linked to original sources
PubMed2001

The coordination and function of the redox centres of the membrane-bound nitrate reductases.

Under anaerobic conditions and in the presence of nitrate, the facultative anaerobe Escherichia coli synthesises an electron-transport chain comprising a primary dehydrogenase and the terminal membrane-bound nitrate reductase A (NarGHI). This review focuses on recent advances obtained on the structure and function of the three protein subunits of membrane-bound nitrate reductases. We discuss a global architecture for the Mo-bisMGD-containing subunit (NarG) and a coordination model for the four [Fe-S] centres of the electron-transfer subunit (NarH) and for the two b-type haems of the anchor subunit NarI.

Cell Membrane↗
PubMed2001

Molecular and clinical follow-up after stem cell transplantation for multiple myeloma.

Molecular follow-up has been carried out using immunoglobulin heavy-chain (IgH) gene finger-printing, a polymerase chain reaction (PCR)-based technique with a sensitivity of 0.1-0.01% (10(-3)-10(-4)), in 22 patients affected by multiple myeloma and submitted to stem cell transplantation (SCT). Twelve patients were submitted to either single or double autologous unselected peripheral blood progenitor cell transplantation, eight patients were submitted to autologous CD34+ immunoselected transplantation and two patients were submitted to allogeneic bone marrow (one patient) or peripheral blood CD34+ stem cell (one patient) transplantation. At diagnosis, all patients showed clonal CDIII rearrangement. The molecular analysis performed on leukapheresis products and CD34+ purified fractions proved to be contaminated by myeloma cells. During follow-up after autografting, all but one patient retained clonal rearrangement despite clinical complete remission (CR) in ten of them. These ten patients either relapsed (Rel) or showed progressive disease (PD) after transplantation; four of them died. Only one patient did not retain clonal rearrangement after autologous transplantation; she is currently alive in CR after a follow-up of 100 months. One patient submitted to allogeneic transplantation is currently alive with no evidence of the disease, but still retains clonal rearrangement after a follow-up of 47 months. Another patient died 4 months after transplantation after succumbing to fatal pneumonia showing myeloma progression.

Adult↗
PubMed2001

Clonal hemopoiesis and risk of thrombosis in young female patients with essential thrombocythemia.

OBJECTIVE: Several studies demonstrated a high prevalence of nonrandom X-chromosome inactivation pattern (X-CIP) in essential thrombocythemia (ET). This study explored the incidence of clonal hemopoiesis in myeloid precursors and endogenous erythroid colonies (EECs) in ET patients and its correlation with thrombotic manifestations. MATERIALS AND METHODS: Clonal analysis of hemopoiesis using X-CIP was performed in 40 female patients with ET. Median age was 40.5 years (range 20-64), and median platelet count at testing time was 700 x 10(9)/L (range 220-1300 x 10(9)/L). Patients older than 65 years were excluded to reduce age-related skewing. Clonality was assessed on neutrophils, platelets, EECs, and bone marrow CD34(+) cells. RESULTS: Eight (20%) of 40 patients developed thrombosis mainly at diagnosis. Clonal hemopoiesis was found in 17 (42.5%) patients, 15 (37.5%) had polyclonal hemopoiesis, and 8 (20%) were considered uninterpretable due to constitutive skewing. Clonality was confirmed on purified CD34(+) subpopulations from bone marrow, documenting that clonality does not appear lineage-restricted. There were no statistical differences in age at diagnosis, median platelet count at testing time, and length of follow-up. Thrombotic episodes were significantly more frequent in the monoclonal group (p = 0.04, Fisher exact test). CONCLUSIONS: Young female patients with ET exhibiting a clonal pattern of hemopoiesis by X-CIP analysis are at higher risk for thrombosis. X-CIP analysis may contribute to defining the individual risk leading to appropriate treatment. X-CIP will allow a correct diagnosis in patients with latent myeloproliferative disorders and thrombosis in unusual sites. Clonal hemopoiesis is easily recognized by X-CIP, but its applicability is limited to the female sex and is hampered by the presence of age-related or constitutive skewing.

Adult↗
PubMed2001

Changes in binding of iodomelatonin to membranes of Leydig cells and steroidogenesis after prolonged in vitro exposure to melatonin.

The aim of the present study was to investigate the effects of prolonged exposure to melatonin (MLT) on the binding of iodomelatonin to membranes of rat Leydig cells and the subsequent modulation of testosterone and cyclic adenocine monophosphate (cAMP) secretion from these cells by MLT itself. Leydig cells were Percoll-purified from adult rats and cultured in vitro with MLT (1--100 nmol/L) for 16 h. Binding assays with 2(125I)iodomelatonin were then performed; moreover, testosterone and cAMP secretion during an acute challenge with lutenizing hormone (LH) (20 mIU/mL for 3 h) was assayed by RIA. As a result of prolonged MLT administration, a decrease in maximum binding density (Bmax) and equilibrium dissociation constant (Kd) of the binding of 2(125I)iodomelatonin to purified cell membranes was noted. Higher testosterone and cAMP secretion during LH challenge were recorded in cells pre-incubated with MLT; notwithstanding, the inhibitory effect of acutely administered MLT on LH-challenged secretions was not only retained but also reinforced, as the IC50 was 30% lower in cells pre-treated with the higher concentration of MLT (100 nM). Cycloheximide administration (10 microg/mL for 16 h) did not prevent hyper-sensitization to LH challenge or to acute MLT administration on LH challenge. Pertussis toxin (180 ng/mL for 16 h) prevented hyper-sensitization to LH, but not to acutely administered MLT. Forskolin (10 nmol/L) administration abolished either phenomena. In conclusion, prolonged exposure to MLT modulates the secretion of testosterone by cultured rat Leydig cells. Although MLT receptors were reduced, hyper-sensitization to LH challenge and to acutely administered MLT on LH challenge were observed with the higher concentration of MLT. Reduction in intracellular cAMP as a result of prolonged administration of MLT, could be the primary cause of both phenomena. On the one hand, reduced cAMP could start re-arrangement of the G-proteins and thus LH-dependent adenylate cyclase sensitization. On the other hand, reduced cAMP could render the Leydig cells more responsive to MLT itself through a mechanism which does not involve G-protein re-arrangement.

Animals↗
PubMed2001

Effects of dietary protein restriction on fibrinogen and albumin metabolism in nephrotic patients.

BACKGROUND: Nephrotic syndrome (NS) is characterized by profound changes in albumin and fibrinogen levels. Dietary protein restriction has been advocated in the treatment of patients with NS, but its effects on albumin and fibrinogen metabolism have not been fully elucidated. METHODS: We evaluated the effects of dietary protein restriction on endogenous leucine flux (ELF), fibrinogen and albumin metabolism in seven patients with NS who consumed either a normal protein diet (NPD; 1.20 +/- 0.06 g/kg/day), or a low protein diet (LPS; 0.66 +/- 0.04 g/kg/day) for four weeks. Seven normal subjects served as controls. The postabsorptive ELF value, fractional synthesis rate (FSR) and absolute synthesis rate (ASR) of both albumin and fibrinogen were evaluated during the last 120 minutes of a five-hour 5,5,5-D3-L-leucine infusion. RESULTS: During the NPD regimen. ELF was increased, serum albumin was reduced, plasma fibrinogen was increased, albumin FSR and ASR were both increased, fibrinogen FSR was normal, and fibrinogen ASR was greater in patients with NS compared to controls. In patients with NS the LPD regimen reduced proteinuria, ELF, albumin FSR and ASR, plasma fibrinogen levels, fibrinogen ASR, and increased serum ulbumin levels. Dietary-induced changes in albumin and fibrinogen synthesis were significantly correlated (r = 0.719, P < 0.05). CONCLUSIONS: Patients with NS treated with LPD show: (1) a reduction of proteinuria, albumin ASR and FSR, with an increase in serum albumin levels and its intravascular pool; (2) a decrease of fibrinogen ASR, with a reduction in both plasma fibrinogen levels and intravascular pool; and (3) a reduced rate of whole body proteolysis.

Adult↗
PubMed2001

Endogenous surfactant turnover in preterm infants with respiratory distress syndrome studied with stable isotope lipids.

We studied surfactant kinetics on Day 1 of life in 11 preterm infants on mechanical ventilation by infusing stable isotope labeled palmitic (PA) and linoleic acid (LLA). Six infants received exogenous surfactant for the treatment of respiratory distress syndrome (RDS) and five did not meet treatment criteria because of minimal or no disease. The isotopic enrichment of plasma free PA and LLA and of surfactant phosphatidylcholine PA (PC-PA) and LLA (PC-LLA) from tracheal aspirates was measured by mass spectrometry. Significant isotopic enrichment could be measured in PC-PA and PC-LLA from all patients. The fractional synthesis rate (FSR) of PC-LLA was higher than that of PC-PA (22.7 +/- 15.9 versus 12.1 +/- 7.7% per day, p = 0.018). Half-life (HL) of PC-PA was longer than that of PC-LLA (94.7 +/- 18.8 versus 46.6 +/- 32.6 h, p = 0.028). Patients who received exogenous surfactant had longer secretion times (ST) and delayed peak times (PK) but FSR and HL were unaffected. We concluded that: (1) surfactant kinetics can be measured in preterm infants with stable isotope labeled lipids; (2) surfactant FSR and HL calculated with PA and LLA gave different results; (3) patients treated with exogenous surfactant had similar FSRs compared with the nontreated subjects but had longer ST and delayed PK; (4) FSR from plasma free fatty acids (present study) was higher than that from plasma glucose in our previous work (Bunt JEH, Zimmermann LJI, Wattimena D, van Beek R, Sauer PJJ, Carnielli VP. Am J Respir Crit Care Med 1998;157:810-814) in a comparable population of preterm infants with RDS.

Humans↗
PubMed2001

[An autopsy case of neonatal lactic acidosis].

Defects in mitochondrial enzymes, such as pyruvate dehydrogenase and cytochrome oxidase, cause hereditary disorders which lead to modifications in cellular pH due to the accumulation of pyruvate and lactic acid. Mitochondrial diseases include severe neonatal diseases and less severe forms of adult diseases. We report the case of lactic acidosis in a newborn girl who was delivered at 36 weeks of gestation and who died 3 months after birth. Her family history revealed a relative with tetraparesis and mental retardation. Her clinical findings, such as tonic-clonic convulsions and accumulation of pyruvate and lactic acid in blood, urine and cerebrospinal fluid, were refractory to treatment and developed soon after birth. Ultrasound scans of the brain some days before death revealed cerebral atrophy with ventricular dilatation and thinning of the corpus callosum and septum pellucidum. The clinical diagnosis of metabolic lactic acidosis was confirmed by macroscopic, microscopic and ultrastructural findings seen at autopsy. On macroscopic examination, the heart was hypertrophic, and the brain was atrophic with ventricular dilatation and thinning of corpus callosum. Small cystic lesions were present in the basal ganglia. On microscopic examination, the latter were characterized by loss of neurons, gliosis and capillary proliferation. Ultrastructural examination of the heart and skeletal muscle showed lysis of myofibrils, mitochondrial pleomorphism and hyperplasia, and crystalline inclusion in mitochondria and in the matrix compartment. In reporting this case, we emphasize the importance of accurate postmortem examination and clinical data for the diagnosis of metabolic lactic acidosis.

Acidosis, Lactic↗
PubMed2000

Rapid and simple determination of inulin in biological fluids by high-performance liquid chromatography with light-scattering detection.

We report a new high-performance liquid chromatography method developed for measuring inulin in plasma and urine using ion moderated partition chromatography and evaporative light-scattering detection. Samples are deproteinized with a zinc acetate and phosphotungstic acid solution and added with melezitose as an internal standard. The chromatographic separation is carried out in 16 min at a flow-rate of 0.6 ml/min using deionized water as the mobile phase. Within-run precision, measured at four different concentrations (0.050 mg/ml, 0.150 mg/ml, 0.300 mg/ml and 1.200 mg/ml), ranges from 1.7 to 3.4% in plasma and from 1.5 to 3.5% in urine. Similarly, between-run precision is in plasma from 2.0 to 4.3% and in urine from 2.0 to 4.4%. Analytical recovery ranges from 97.9 to 100.1% in plasma and from 99.1 to 99.7% in urine, respectively. Detection limit (signal-to-noise ratio=3) is 5 microg/ml both in plasma and urine. The method is simple, sensitive, without interference due to hexoses or drugs commonly taken by patients with renal diseases, and offers the advantage of measuring inulin without previous hydrolysis of the molecule.

Adolescent↗
PubMed2000

Novel growth characteristics and high rates of nitrate reduction of an Escherichia coli strain, LCB2048, that expresses only a periplasmic nitrate reductase.

Escherichia coli strain LCB2048 is a double mutant defective in the synthesis of the two membrane-associated nitrate reductases A and Z. This strain can grow anaerobically on a non-fermentable carbon source, glycerol, in the presence of nitrate even in media supplemented with high concentrations of tungstate. This growth was totally dependent upon a highly active, periplasmic nitrate reductase (Nap). Due to the presence of a previously unreported narL mutation, synthesis of the periplasmic nitrate reductase by this strain was induced during anaerobic growth by nitrate. We have also demonstrated that methyl viologen is an ineffective electron donor to Nap: its use leads to an underestimation of the contribution of Nap activity to the rate of nitrate reduction in vivo.

Anaerobiosis↗
PubMed2000

Eversion versus conventional carotid endarterectomy: late results of a prospective multicenter randomized trial.

OBJECTIVE: The durability of carotid endarterectomy (CEA) may be affected by carotid restenosis. The data from randomized trials show that the highest incidence of restenosis after CEA occurs from 12 to 18 months after surgery. The optimal CEA technique to reduce perioperative complications and restenosis rates is still undefined. This study examines the long-term clinical outcome and incidence of recurrent stenosis in patients who undergo eversion CEA. Previously published perioperative results of this study did not show statistically significant differences in study endpoints between the eversion and standard techniques. METHODS: From October 1994 to March 1997, 1353 patients with surgical indications for carotid stenosis were randomly assigned to undergo eversion (n = 678) or standard CEA (n = 675; primary closure, 419; patch, 256). Withdrawal from the assigned treatment occurred in 1.6% of the patients (in 13 assigned to eversion CEA, and in nine assigned to standard CEA). The clinical and duplex scan follow-up examination was 99% complete, and the mean follow-up interval was 33 months (range, 12 to 55 months). The primary outcomes were perioperative and late major stroke and death, carotid restenosis (stenosis >/= 50% of the lumen diameter detected at duplex scanning), and carotid occlusion. The primary evaluation of study outcomes was conducted on the basis of an intention-to-treat analysis. RESULTS: Restenosis was found at duplex scanning in 56 patients (19 in the eversion group, and 37 in the standard group). Within the standard group, the restenosis rates were 7.9% in the primary closure population and 1.5% in the patched population. Of the patients with restenosis, 36% underwent cerebral angiography that confirmed restenosis in all cases. The cumulative restenosis risk at 4 years was significantly lower in the group that underwent treatment with eversion CEA as compared with the standard group (3.6% vs 9.2%; P =.01), with an absolute risk reduction of 5. 6% and a relative risk reduction of 62%. Eighteen patients would have had to undergo treatment with eversion CEA to prevent one restenosis during the 4-year period. The incidence rate of ipsilateral stroke was 3.3% in the eversion population and 2.2% in the standard group. There were no significant differences in the cumulative risks of ipsilateral stroke (3.9% for eversion, and 2.2% for standard; P =.2) and death (13.1% for eversion, and 12.7% for standard; P =.7)) in the two groups. Of the 18 variables that were examined for their influence on restenosis, eversion CEA (hazard ratio, 0.3; 95% confidence interval, 0.2 to 0.6; P =.0004) and patch CEA (hazard ratio, 0.2; 95% confidence interval, 0.07 to 0.6; P =. 002) were negative independent predictors of restenosis with multivariate Cox proportional hazards regression analysis. CONCLUSION: The EVEREST (EVERsion carotid Endarterectomy versus Standard Trial) showed that eversion CEA is safe, effective, and durable. No statistically significant differences were found in late outcome between the eversion and standard techniques at the available follow-up examination.

Actuarial Analysis↗
PubMed2000

A genetic study of natural flor strains of Saccharomyces cerevisiae isolated during biological ageing from Sardinian wines.

In this study, three flor strains of Saccharomyces cerevisiae were genetically characterized. They were isolated from biofilms on Sardinian sherry-like wines produced at family-run wineries where pure cultures of yeasts were not used. The study aimed to investigate the life cycle of these naturally-occurring flor strains, using a genetic procedure supplemented by analysis of subsequent meiotic generations. A semi-homothallic life cycle was found in three strains that could be helpful in a genetic improvement programme.

Italy↗
PubMed2000

Exogenous surfactant kinetics in infant respiratory distress syndrome: A novel method with stable isotopes.

Little is known about surfactant metabolism in newborn infants, since radioactive isotopes cannot be used in humans. We describe here a new method for studying exogenous surfactant pharmacokinetics in vivo. We measured surfactant half-life, pool size, and turnover time in eight preterm infants (gestational age: 30 +/- 2 wk; birth weight: 1,416 +/- 202 g) who were mechanically ventilated because of infant respiratory distress syndrome. We administered two doses of 100 mg/kg each of a natural porcine surfactant with (13)C-labeled dipalmitoylphosphatidylcholine as a tracer. The (13)C enrichment of surfactant disaturated phosphatidylcholine (DSPC) was measured in serial tracheal aspirates by gas chromatography-mass spectrometry. The DSPC half-life was 34.2 +/- 9.4 h (mean +/- SD; range: 21.8 to 45.9 h). The apparent DSPC pool sizes were 5.8 +/- 6.1 mg/kg (range: 0.1 to 17.0 mg/kg) and 17.3 +/- 13.6 mg/kg (range: 3.3 to 41.0 mg/kg) at the time of the first and second surfactant doses, respectively. We present a novel and safe method that allows the tracing of exogenous surfactant phosphatidylcholine, the major lipid component of pulmonary surfactant, in infants who receive exogenous surfactant. This method could be a valuable tool for studying: (1) therapies that enhance lung/surfactant maturation; (2) the dosing and timing of surfactant therapy in different lung diseases; and (3) the comparison of different surfactant preparations.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2000

Serum leptin concentrations during the menstrual cycle in normal-weight women: effects of an oral triphasic estrogen-progestin medication.

OBJECTIVE: To investigate in normal-weight premenopausal women the relationship between circulating leptin and serum gonadotropins and gonadal steroids, during both spontaneous and pharmacologically induced menstrual cycles. DESIGN: Clinical longitudinal study. METHODS: Two groups of age-matched, normal-weight premenopausal volunteer women (groups I and II) were enrolled in this study. Women in group I were free of any hormonal treatment, while women in group II were taking a triphasic estrogen--progestin contraceptive preparation. Blood samples were collected daily in both groups after an overnight fast throughout a complete menstrual cycle. RESULTS: In the spontaneously cycling women, serum leptin concentration positively correlated with estradiol (P<0.03) and progesterone (P<0. 05) and was higher in the luteal than in the follicular phase (P<0. 05). However, a significant (P<0.03) short-lasting increase in circulating leptin was present in the late follicular phase of all subjects. In the women using hormonal contraception serum leptin remained unchanged throughout the cycle, along with constantly low values of circulating luteinizing hormone and follicle-stimulating hormone. CONCLUSIONS: In normal-weight premenopausal women serum leptin concentrations differ during the menstrual cycle in line with changes in gonadotropin and gonadal steroid concentrations, increasing in the luteal phase of the cycle after a peri-ovulatory peak. These findings suggest a permissive role for leptin with regard to the functioning of the corpus luteum.

Adult↗