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G Chirico

Publications and source records attributed to G Chirico.

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

Two-photon microscopy and spectroscopy based on a compact confocal scanning head.

We have combined a confocal laser scanning head modified for TPE (two-photon excitation) microscopy with some spectroscopic modules to study single molecules and molecular aggregates. The behavior of the TPE microscope unit has been characterized by means of point spread function measurements and of the demonstration of its micropatterning abilities. One-photon and two-photon mode can be simply accomplished by switching from a mono-mode optical fiber (one-photon) coupled to conventional laser sources to an optical module that allows IR laser beam (two-photon/TPE) delivery to the confocal laser scanning head. We have then described the characterization of the two-photon microscope for spectroscopic applications: fluorescence correlation, lifetime and fluorescence polarization anisotropy measurements. We describe the measurement of the response of the two-photon microscope to the light polarization and discuss fluorescence polarization anisotropy measurements on Rhodamine 6G as a function of the viscosity and on a globular protein, the Beta-lactoglobulin B labeled with Alexa 532 at very high dilutions. The average rotational and translational diffusion coefficients measured with fluorescence polarization anisotropy and fluorescence correlation methods are in good agreement with the protein size, therefore validating the use of the microscope for two-photon spectroscopy on biomolecules.

Animals↗
PubMed2000

Role of pyridoxal 5'-phosphate in the structural stabilization of O-acetylserine sulfhydrylase.

Proteins belonging to the superfamily of pyridoxal 5'-phosphate-dependent enzymes are currently classified into three functional groups and five distinct structural fold types. The variation within this enzyme group creates an ideal system to investigate the relationships among amino acid sequences, folding pathways, and enzymatic functions. The number of known three-dimensional structures of pyridoxal 5'-phosphate-dependent enzymes is rapidly increasing, but only for relatively few have the folding mechanisms been characterized in detail. The dimeric O-acetylserine sulfhydrylase from Salmonella typhimurium belongs to the beta-family and fold type II group. Here we report the guanidine hydrochloride-induced unfolding of the apo- and holoprotein, investigated using a variety of spectroscopic techniques. Data from absorption, fluorescence, circular dichroism, (31)P nuclear magnetic resonance, time-resolved fluorescence anisotropy, and photon correlation spectroscopy indicate that the O-acetylserine sulfhydrylase undergoes extensive disruption of native secondary and tertiary structure before monomerization. Also, we have observed that the holo-O-acetylserine sulfhydrylase exhibits a greater conformational stability than the apoenzyme form. The data are discussed in light of the fact that the role of the coenzyme in structural stabilization varies among the pyridoxal 5'-phosphate-dependent enzymes and does not seem to be linked to the particular enzyme fold type.

Cysteine Synthase↗
PubMed2000

Early immunisation with hepatitis B vaccine: a five-year study.

We evaluated the response to the recombinant Hepatitis B vaccine using an accelerated schedule versus the traditional schedule by studying the immunologic memory induced in 200 children with HBs-Ag negative mothers. At seroconversion, the traditional schedule presented a higher percentage of children with serum HBs-Ag concentrations over 100 mIU/ml than the accelerated schedule. After five years this difference was no longer statistically significant and children who presented anti-HBsAg concentrations below 10 mUI/ml received an additional booster dose which stimulated the antibody concentration to exceed 100 mIU/ml in all cases. Recombinant HBV vaccine induced better long term immunologic memory when it was administered earlier.

Antibodies↗
PubMed2000

Unusual polyarthritis as a unique clinical manifestation of coeliac disease.

This report describes a patient who presented with an unusual polyarthritis accompanied by myalgia, fever and anxiety. After extensive clinical and serological evaluation, duodenal biopsy and serological tests provided evidence for the diagnosis of coeliac disease (CD). The patient was promptly put on a gluten-free diet, which led to an improvement in the clinical abnormalities.

Adult↗
PubMed2000

Immunophenotypic changes of fetal cord blood hematopoietic progenitor cells during gestation.

We measured cell surface expression of CD34, HLA-DR, CD38, CD19, CD33, CD71, and CD45 antigens in the hematopoietic progenitor cells of fetal cord blood to investigate immunophenotypic changes at different gestational ages. These antigens were identified by flow cytometry in 11 fetuses (gestational age 19-24 wk, in 12 preterm (25-28 wk) and in ten newborn infants born at term. The frequency and number of CD34+ cells were higher in the blood of the 11 fetuses; in addition, a statistically significant inverse correlation between number of CD34+ cells and advancing gestational age was noted. The numbers of CD34+ CD19+, CD34+ CD33+, and CD34+ CD45+ coexpressing cells were significantly higher in the fetuses, whereas CD34+ CD38+ cells were more represented in the neonates at term. Gestational age was inversely correlated with the number of CD34+ CD19+ and CD34+ CD33+ coexpressing cells. A positive correlation between gestational age and CD34+ CD38+ cells was noted. The number of CD34- CD19+, CD34- CD38+, and CD34- CD45+ cells was higher in term infants; furthermore, a significant correlation between advancing gestational age and CD34- CD38+ or CD34- CD45+ cells was demonstrated. The proliferative capacity was also higher at lower gestational ages. These data suggest that the development and lineage commitment of fetal cord blood hematopoietic progenitor cells are very active during the last two trimesters of pregnancy. The most significant changes of hematopoietic cells maturation seem to occur within 25 wk of gestation.

Antigens, CD↗
PubMed1999

Hematopoietic growth factor levels in term and preterm infants.

The problems of immunologic adaptation during the transitional period from intra- to extrauterine life are responsible for the physiologic immaturity of the immune function in newborn infants. In preterm neonates the immunodeficiency is more severe and prolonged and is associated with a higher incidence of infections and sepsis. Furthermore, due to immaturity of the hematologic system, anemia, thrombocytopenia, and neutropenia are frequently observed in very low birth weight infants. The dysregulation of cytokine and hematopoietic growth factor synthesis is an important contributory factor to the complex deficiency of immunologic and hematologic function in the neonate and may explain the reduced incidence of acute graft-versus-host disease observed after cord blood transplantation in children. Human milk is a rich source of most of the cytokines that are reduced in the neonate. Granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and erythropoietin are currently under evaluation in newborn infants with septic neutropenia or anemia of prematurity.

Granulocyte Colony-Stimulating Factor↗
PubMed1999

Polyion character of globular proteins detected by translational and rotational diffusion.

Photon correlation spectroscopy measurements are performed on a solution of lysozyme, a small, highly charged protein at pH=4, in glycerol-buffer mixtures. From the correlation functions of the polarized and depolarized scattered intensity, we derive an effective protein radius by inverting the Stokes Einstein relation for either the translational or the rotational diffusion, as a function of the protein concentration 0< or =C< or =40 g/L. The translational radius decreases with the protein concentration and extrapolates at C approximately 0 to a value slightly larger than the mean rotational radius, which is independent of the protein concentration. By employing recent calculations on electrolyte friction effects (eletrolyte-protein interactions) on both the translational and rotational radius and by keeping also into account the protein-protein electrostatic interactions, we are able to account for the observed differences, suggesting also that lysozyme is more highly hydrated in glycerol mixtures than in the pure buffer. These results indicate that depolarized photon correlation spectroscopy measurements can be used as a valuable tool to detect small changes in the overall protein size.

Acetates↗
PubMed1999

Leukocyte counts in relation to the method of delivery during the first five days of life.

The goal of the present study was to evaluate total and differential leukocyte counts during the first 5 days of life in relation to the method of delivery. We included 203 healthy term infants; of these, 114 were born by vaginal delivery, and 89 by elective cesarean section. Total and differential leukocyte counts were evaluated at the following intervals: 0-6, 7-12, 13-24, 25-48, 49-72, 73-96, and 97-120 h after birth. The cord serum cortisol level was measured as an indicator of the degree of delivery-related stress. Mean leukocyte and neutrophil counts were higher in infants born by vaginal delivery in cord blood and up to 12 h of life. No significant differences were observed in the immature: total neutrophil ratios between the two groups of infants. The cord serum cortisol level was higher in vaginally delivered infants. A significant correlation was found between cortisol and leukocyte, neutrophil, or lymphocyte counts. The method of delivery produces significantly different total leukocyte and neutrophil counts during the first 12 h after birth; after this time, there appears to be no more variation of leukocyte counts during the first 5 days of life.

Cesarean Section↗
PubMed1999

Natural killer cell activity and delivery: possible influence of cortisol and anesthetic agents. A study on newborn cord blood.

The aim of this study was to evaluate the influence of the method of delivery, the level of cord blood lidocaine, and the cortisol concentration on the cord blood natural killer (NK) activity in the full-term healthy newborn. We studied healthy newborns delivered by elective cesarean section without labor under general anesthesia (n = 24), delivered by cesarean section under epidural anesthesia (n = 21), and delivered vaginally with uncomplicated labor (n = 19). The NK cell activity was significantly lower in newborns delivered by cesarean section under epidural anesthesia than it was in the general anesthesia group, while it was similar to the levels found in vaginally delivered newborns. The cortisol concentration was highest in the vaginal delivery group (589.2 +/- 200 mmol/l) and lowest in the general anesthesia group (199.2 +/- 81.9 mmol/l). The mean serum lidocaine concentration was 414.1 +/- 370 microgram/l in the epidural anesthesia group and undetectable in the other groups. In conclusion, our data suggest that the cord blood NK activity was significantly influenced by the method of delivery. This effect could be related to anesthetics given to the mother for general or epidural anesthesia or to the endocrine-metabolic variations observed after different degrees of delivery-related stress. The NK cells being a first-line defense mechanism against viral infections, the results of this study suggest an association with the occurrence of early perinatal infections, especially in preterm infants.

Anesthesia, Epidural↗
PubMed1998

Triple helix DNA oligomer melting measured by fluorescence polarization anisotropy.

A synthetic DNA triple helix sequence was formed by annealing a pyrimidinic 21 mer single strand sequence onto the complementary purinic sequence centred on a 27 mer duplex DNA. Melting of the third strand was monitored by UV spectrophotometry in the temperature range 10-90 degrees C. The T(m) of the triplex, 37 degrees C, was well separated from the onset of duplex melting. When the same triple helix was formed on the duplex bearing one nick in the center of the pyrimidinic sequence the T(m) of the triplex was shifted to approximately 32 degrees C and overlapped the melting of the duplex. We have used fluorescence polarization anisotropy (FPA) measurements of ethidium bromide (EB) intercalated in duplex and triplex samples to determine the hydrodynamic parameters in the temperature range 10-40 degrees C. The fluorescence lifetime of EB in the samples of double and triple stranded DNA is the same (21.3 +/- 0.5 ns) at 20 degrees C, indicating that the geometries of the intercalation sites are similar. The values for the hydration radii of the duplex, normal triplex, and nicked triplex samples were 10.7 +/- 0.2, 12.2 +/- 0.2, and 12.0 +/- 0.2 A. FPA measurements on normal triplex DNA as a function of temperature gave a melting profile very similar to that derived by UV absorption spectroscopy. For the triplex carrying a nick, the melting curve obtained using FPA showed a clear shift compared with that obtained for the normal triplex sample. The torsional rigidity of the triplex forms was found to be higher than that of the duplex form.

Base Sequence↗
PubMed1998

Revaccination against hepatitis B virus of non-responding and low-responding infants immunised at birth. A parallel evaluation of rubella and tetanus vaccine.

The aim of the present study was to identify the true extent of the non-responsiveness in infants born from HBsAg-negative mothers, vaccinated against Hepatitis B Virus (HBV) at birth. Sixty-four non- and low-responding infants, selected from an initial cohort of 2009, were given two additional doses of recombinant HBV vaccine between the tenth and the twelfth month of age. A parallel evaluation was conducted on the response to anti-rubella and anti-tetanus vaccine. Only two infants remained non-responders, whereas 68% of the non-responders and 94% of the low responders after the primary vaccination schedule developed antibody titres over 100 mIU ml-1. No significant relationship between the specific antibody level against HBV and against rubella or tetanus 1 month after vaccination was observed.

Hepatitis B↗
PubMed1998

The influence of race on breast feeding.

We evaluated the beginning of lactogenesis and the milk quantity until the fifth post-delivery day, before discharge, in 10 primiparae and 11 pluriparae Gypsies, as compared to 12 primiparae and 11 pluriparae Italian women. The results showed that both in primiparae and in pluriparae Gypsies, the lactogenesis started significantly earlier and the milk quantity was significantly greater than in Italian women.

Adult↗
PubMed1998

Effect of lidocaine on neutrophil chemotaxis in newborn infants.

Anesthetic drugs can influence the immune system, particularly granulocyte function. The goal of the present study was to evaluate if lidocaine used for epidural anesthesia during cesarean section can influence neonatal neutrophil chemotaxis. We measured chemotaxis and plasma cord lidocaine and cortisol levels in (A) 15 infants born by cesarean section with epidural anesthesia, (B) 15 infants born by vaginal delivery, and (C) 20 infants born by cesarean section with general anesthesia. Chemotaxis levels were significantly lower in group A infants (35.5 +/- 16.1 microns) compared to groups B (54.6 +/- 10.5 microns) and C (71.4 +/- 23 microns). The highest cortisol levels were observed in vaginally delivered infants. A significant inverse relationship was observed between chemotaxis and lidocaine levels (r = -0.6, P = 0.016) in infants born by cesarean section after epidural anesthesia, while no significant correlation was observed between chemotaxis and cortisol level. In conclusion, lidocaine, transferred through the placenta to the fetus during epidural anesthesia, may have an inhibitory effect on chemotaxis.

Anesthesia, Epidural↗
PubMed1998

Immunogenicity of hepatitis B vaccine in term and preterm infants.

Some studies have suggested that decreased seroconversion rates might be found in premature infants with low birthweight (< 2000g) following administration of hepatitis B vaccine at birth. The aim of the present investigation was to evaluate possible differences in seropositive rates between full-term and preterm infants after primary vaccination, in particular when gestational age or birthweight is very low. Two-thousand and nine neonates born to HBsAg-negative mothers were vaccinated with 10 microg of recombinant hepatitis B virus (HBV) vaccine, from May 1991 to October 1994. Children with infections, congenital malformations or serious illnesses were excluded. HBV vaccine was administered intramuscularly, on the fourth day of life and again at 1 and 6 months of age. A 1-ml blood sample was drawn from each infant 1 month after the third vaccine dose for determination of the level of anti-HBs antibody. The response to HBV vaccination was evaluated in 241 preterm (gestational age <38 weeks) infants and 1727 term neonates. No statistical difference was observed in the distribution of anti-HBs antibody level, either between preterm infants (<38 weeks) and newborns of normal gestational age, or between low birthweight (<2500 g) and normal weight infants. The results suggest that preterm and low birthweight infants (<2500g) respond to HBV vaccine in the same measure as normal-term infants.

Analysis of Variance↗
PubMed1998

Placental transfer favours high avidity IgG antibodies.

The aim of the present study was to evaluate if maternal-foetal antibody placental transfer may be affected by antibody avidity. We compared the avidity index (AI) of IgG antibodies to tetanus toxoid (TT) and to type 3 pneumococcal antigen (Pn) in cord blood of 10 healthy term and 8 preterm infants and in their mothers' sera at delivery. In order to evaluate whether a heavier antigenic exposure may influence the placental transfer, we also studied 15 Pakistani maternal sera and cord blood pairs. TT- and Pn-specific antibody AI was significantly higher in Italian and Pakistani term infants than in their mothers, while a significant difference in specific TT antibody AI, but not in specific Pn antibody AI was observed between preterm infants and their mothers. Italian and Pakistani cord blood/maternal serum pairs showed comparable values of AI. Our data suggest that high avidity antibodies preferentially cross the placenta; this seems to start early during gestation and appears to be related to the nature of the antigen to which the antibodies are directed, but not to the degree of antigenic exposure.

Antibody Affinity↗
PubMed1998

Effect of passive smoking on thyroid function in infants.

OBJECTIVE: To evaluate the effect of passive smoking on thyroid function in infants. DESIGN AND METHODS: Cord serum tri-iodiothyronine (T3), free T3 (fT3), thyroxine (T4), free T4 (fT4), TSH, thyroxine binding globulin (TBG), thyroglobulin (TG) and cord plasma thiocyanate were measured at birth, and serum TG and thiocyanate after 1 year of life, in 18 infants born from parents who did not smoke (group A), in 18 infants with a father who smoked (group B) and in 18 infants with parents both being smokers (group C). RESULTS: No significant differences were observed in cord serum concentrations of T3, fT3, T4, fT4, TSH and TBG among the three groups. Median (range) TG concentrations (ng/ml) were 30.2 (5.0-102.0), 56.3 (20.5-208.0) and 76.0 (26.0-199.0) at birth (P=0.009 for groups A and B compared; P=0.0002 for groups A and C compared), and 14.9 (5.4-32.0), 19.5 (10.0-57.5) and 20.0 (14.0-40.7) at 1 year (P=0.017 for groups A and C compared), in the three groups respectively, and thiocyanate concentrations (mmol/l) were 3.3 (0.0-51.4), 12.9 (0.0-122.2) and 27.8 (3.3-184.5) at birth (P=0.015 for groups A and C compared), and 3.1 (0.0-32.7), 6.0 (0.0-47.3) and 20.3 (0.0-230.8) at 1 year (P=0.01 for groups A and C compared) in the three groups respectively. CONCLUSIONS: TG and thiocyanate concentrations at birth and at 1 year of age in infants of smoking parents are greater than in infants with non-smoking parents. These results indicate that the change in thyroid function as evaluated by serum TG concentrations observed at birth can persist at least for 1 year if the exposure to passive smoking from both parents is continued. Increased TG concentrations may be due to a direct effect of thiocyanate on the thyroid gland.

Analysis of Variance↗