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Biomedical subjects

D Ricci

Publications and source records attributed to D Ricci.

At least 19 recordsLinked to original sources
PubMed2006

Maturation of cerebral electrical activity and development of cortical folding in young very preterm infants.

OBJECTIVE: The aim of this study was to examine the relationship between cortical development and cerebral electrical activity at early gestational ages. METHODS: We obtained EEGs (7.2+/-3.8 days) and MR brain images (3.2+/-2.9 days) after birth in 17<30 week gestation infants without evidence of focal brain injury The EEGs were assessed for discontinuity and characteristic maturational features (delta brush, occipital and temporal sawtooth); cortical development was quantified from MR scans using a specially designed computer programme to measure cortical folding. RESULTS: The inter-burst interval shortened and cortical folding increased with increasing post-menstrual age (PMA). In contrast, the minimum duration of bursts was independent of PMA and cortical folding. Delta brush (8-20 Hz activities) was seen at all PMAs; temporal and occipital sawtooth activities were always more prominent than delta brush but were seen less frequently with increasing PMA and complexity of cortical folding. CONCLUSION: There was a positive correlation between some but not all maturational features of the preterm neonatal EEG and the complexity of whole brain cortical folding and PMA. These relationships were strong for the inter-burst interval, a global measure of maturation, but not strongly seen for regional features such as occipital and temporal sawtooth within this gestational age range. SIGNIFICANCE: Combining neurophysiological examination with detailed neuroimaging gives insights into developmental changes occurring in the very preterm brains and suggests further comparative studies focusing on measures of focal brain development at different gestational ages.

Cerebral Cortex↗
PubMed2006

Effects of intracellular pH and Ca2+ on the activity of stretch-sensitive cation channels in leech neurons.

The effects of intracellular pH and calcium on the activity of the leech mechanosensitive cation channels have been studied. These channels exhibited two activity modes denoted as spike-like (SL) and multiconductance (MC). In the absence of mechanical stimulation, acidification of the intracellular side of membrane patches from 7.2 to 6.2 reversibly increased the mean channel open time as well as the opening frequency in the SL mode. Channels in MC mode were activated by a pH(i) reduction from 7.2 to 6.2, but were inhibited at pH(i) 5.5. Unlike MC mode, SL mode was strongly activated by intracellular Ca(2+). Fura-2 imaging experiments showed that intracellular calcium was induced to increase by hypotonic cell swelling. The major component of this response did not require extracellular calcium. A component of the swelling-induced calcium response was sensitive to blockers of stretch-sensitive cation channels. The results indicate that the two activity modes of mechanosensitive channels of leech neurons respond differently to changes of intracellular pH and calcium. The sensitivity of the channel to micromolar concentrations of internal free calcium, along with its permeability to this ion, is consistent with a role in the amplification of mechanically induced Ca(2+) signals in leech neurons.

Action Potentials↗
PubMed2006

Auditory attention at the onset of West syndrome: correlation with EEG patterns and visual function.

At the onset of West syndrome a specific impairment of visual function has been clearly demonstrated, while other aspects of sensorial development, and in particular of the auditory function, have been less studied. The aim of this study was to evaluate auditory function and orienting responses at the onset of West syndrome, and to relate the results with EEG patterns, visual function and neurodevelopmental competence. A prospective multicentric study was performed on 25 successively enrolled infants with West syndrome; all the patients underwent a full clinical assessment, including MRI and video-EEG, visual function and auditory orienting responses (AORs) as well as Griffiths' developmental scales. The whole assessment performed at the onset of spasms (T0) was repeated after two months (T1). AORs resulted significantly impaired both at T0 and T1. At the onset of spasms a highly significant relationship of auditory attention with visual function and neurodevelopmental competence was shown in both cryptogenic and symptomatic forms, but it was no longer present after two months. Our results may suggest a possible pervasive effect of the epileptic disorder on sensory processing, associated to a deficit of neurodevelopment. Although we failed to show a significant correlation between auditory orienting responses and EEG patterns, some evidence seems to support at least partially an influence of the epileptic disorder per se on the genesis of the sensorial impairment. A longer follow up and a larger cohort will be useful for a better clarification of these findings.

Acoustic Stimulation↗
PubMed2006

Sequential neurological examinations in infants with neonatal encephalopathy and low apgar scores: relationship with brain MRI.

OBJECTIVE: The aims of this study were to (a) describe the evolution of neurological signs after the neonatal period in infants with neonatal encephalopathy and abnormal outcome and (b) to establish the relationship between the evolution of neurological signs and patterns of lesions on brain MRI. PATIENTS: Fifteen children with low Apgar scores, abnormal neurological signs at the end of the neonatal period, and abnormal outcome were examined at 1 - 2 weeks, 5 - 7 weeks, and 6 months. All the infants had at least one MRI scan performed in the neonatal period. RESULTS: All infants had persistent abnormalities on all examinations performed but the severity of neurological impairment was variable and was related to the pattern of brain lesions. Infants with severe basal ganglia and white matter lesions showed abnormal axial and limb tone, movements, and visual function on all the examinations and none achieved independent sitting. In infants with moderate basal ganglia lesions and/or severe white matter changes, visual function and feeding improved by 5 - 7 weeks and were still normal at 6 months while limb tone, which was reduced in the first weeks, appeared to be normal at 5 - 6 weeks but was found to be increased at 6 months; all were able to sit unsupported at 2 years and most of them achieved the ability to walk with support. CONCLUSIONS: Our results suggest that the evolution of the neurological patterns after the neonatal period in infants with persisting neonatal abnormalities depends on their pattern of brain lesions.

Apgar Score↗
PubMed2006

Neurological examination at 6 to 9 months in infants with cystic periventricular leukomalacia.

The Hammersmith Infant Neurological Examination was performed in 24 infants with cystic periventricular leukomalacia whose gestational age ranged between 26-38 weeks. The infants were examined between 6 and 9.5 months corrected age. The aim of the study was to establish the different patterns of neurological abnormality as well as the optimality scores that predict the severity of motor sequelae at 2 years. Increased neck and trunk extensor tone, and a posture of flexed arms and extended legs between 6 and 9 months were always associated with the inability to sit unsupported at 2 years, whilst truncal hypotonia and extended arms and legs were associated with unsupported sitting but not walking. Optimality scores between 41 and 60 were generally associated with sitting but not walking at 2 years whilst scores below 40 were always associated with the inability to sit independently at 2 years. All infants who did not develop cerebral palsy at 2 years had scores > 60. Our results suggest that the pattern of findings on neurological examination performed between 6 and 9 months as well as the calculated optimality score helps to predict motor impairment in infants with PVL.

Female↗
PubMed2006

Molecular adsorbent recirculating system (MARS) application in liver failure: clinical and hemodepurative results in 22 patients.

PURPOSE: Acute liver failure (ALF) and acute on chronic liver failure (ACLF) still show a poor prognosis. MARS was used in 22 patients with ALF or ACLF to prolong patient survival for liver function recovery or as a bridge to transplantation. DESIGN: Evaluation of depurative efficiency, biocompatibility, hemodynamics, encephalopathy (HE) and clinical outcome. PROCEDURES: During 71 five-hour sessions we evaluated (0', 60', 120', 180', 240', 300'): bilirubin, ammonia, cholic acid (CCA), chenodeoxycholic acid (CCDCA), leukocytes, platelets, hemoglobin and mean arterial pressure (MAP). Serum creatinine, electrolytes, cardiac output, cardiac index (bioimpedence) and HE (West Haven Criteria score) were evaluated at 0' and 300'. STATISTICAL METHODS AND OUTCOME MEASURES: Student's t-test for pre- vs. end-session values was used. For bilirubin and ammonia the correlation test was made between pre- and end-session values and between pre-session values and removal rates (RRS). MAIN FINDINGS: Survival was 90.9% at 7 days, 40.9% at 30 days. Pre- vs. end-session: bilirubin from 37.2 +/- 12.5 mg/dL to 24.9 +/- 8.9 mg/dL (p < 0.01), ammonia from 88.0 +/- 60.4 micromol/L to 43.6 +/- 32.9 micromol/L (p < 0.01), CCA from 42.8 +/- 21.0 micromol/L 18.2 +/- 9.8 micromol/L (p < 0.01), CCDCA from 26.3 +/- 6.3 micromol/L to 15.7+/-7.6 micromol/L (p<0.01). The correlation test between pre-session values of bilirubin and ammonia vs. RR S was respectively 0.32 (p = 0.01) and 0.30 (p = 0.04). Leukocytes, platelets and hemoglobin remained stable. MAP increased from 82.0 +/- 12.0 mmHg to 87.0 +/- 13.0 mmHg (p < 0.05), West Haven Criteria score decreased from 2.7 +/- 0.7 to 0.7 +/- 0.7 (p < 0.001). CONCLUSION: MARS treatment led in all patients to an improvement of clinical, hemodynamic and neurological conditions, with significant reduction in the hepatic toxins blood level. Treatment biocompatibility and tolerance were satisfactory.

Acute Kidney Injury↗
PubMed2005

Lapine rotaviruses of the genotype P[22] are widespread in Italian rabbitries.

An epidemiological survey was carried out to investigate the distribution of the VP7 and VP4 specificities of lapine rotaviruses (LRVs) in rabbitries from different geographical regions of Italy. Almost all the strains were characterized as P[22],G3, confirming the presence of the newly-recognized rotavirus P[22] VP4 allele in Italian rabbits. Only one P[14],G3 LRV strain was identified and two samples contained a mixed (P[14] + [22],G3) rotavirus infection. All the LRV strains analyzed exhibited a genogroup I VP6 specificity and a long dsRNA electropherotype. However, one of the P[14],G3 strains possessed a super-short pattern. Altogether, these data highlight the epidemiological relevance of the P[22] LRVs in Italian rabbitries.

Amino Acid Sequence↗
PubMed2005

Assessment of visual function in children with methylmalonic aciduria and homocystinuria.

The aim of this study was to assess various aspects of visual function in 6 patients (age range: 9 months to 7 years and 8 months) with methylmalonic aciduria and homocystinuria. All patients had an ophthalmological examination and were tested with a battery of age-appropriate tests assessing various aspects of visual function such as acuity, visual fields and visual attention. None of the patients had significant retinal abnormalities but all 6 had nystagmus which was associated with strabismus in 3 of the 6. They all had some abnormalities on the behavioral tests assessing visual function which appeared to be related to the age of the patients. Visual impairment was more severe in the 3 patients below 3 years of age and milder in the older patients. The presence and the severity of abnormalities, in contrast, did not depend on the age at onset or the age when treatment was started and were only partly related to brain MRI findings. Severe hydrocephalus and basal ganglia involvement were associated with severe visual impairment, but abnormal visual findings were also present in the children with normal MRI and isolated mild periventricular changes. Our results suggest that age, brain lesions and other factors may be responsible for visual abnormalities in methylmalonic aciduria and homocystinuria. Further studies using early and sequential assessment of visual function are needed to establish whether the differences observed between younger and older children may be related to the duration of therapy.

Attention↗
PubMed2005

Does cranial ultrasound imaging identify arterial cerebral infarction in term neonates?

OBJECTIVE: To evaluate the diagnostic accuracy of cranial ultrasound (CUS) for detection of neonatal arterial territory cerebral infarction in term infants. METHODS: CUS scans from term infants with neonatal magnetic resonance imaging (MRI) evidence of neonatal infarction were reviewed. The scans were grouped by acquisition time after birth: 1-3 days (early) or 4-14 days (late). RESULTS: Brain MRI showed infarction in the territory of the middle cerebral artery in 43 of 47 infants, anterior cerebral artery in one, and posterior cerebral artery in three. Twelve of the 47 had minor changes on MRI in the white matter in the contralateral hemisphere, and four infants had bilateral infarctions. The early CUS scans were abnormal in 68% of the infants; the late CUS scans were abnormal in 87%. The late CUS scans were correct for laterality and site of lesion in 25/47 (53%) infants. In six infants with smaller lesions of the cortical middle cerebral artery branch or lesions in the posterior cerebral artery territory, the CUS scans were persistently normal. CONCLUSION: Normal early CUS scans do not exclude a diagnosis of neonatal stroke, although most scans are abnormal. CUS scans performed after day 3 were abnormal in 87% of infants. CUS scan findings were accurate for lesion laterality and site in 53%, and, in 34%, the scans showed abnormality strongly suggestive of infarction but not always site specific. For optimal prognostic information, infants with clinical histories or CUS scan findings suggestive of infarction should have a neonatal brain MRI scan.

Age Factors↗
PubMed2004

Evaluation of lactogenic immunity to canine parvovirus in pups.

Maternally-derived antibodies (MDA) transferred to pups through colostrum and milk are known as lactogenic immunity. In this report, we describe the kinetics of transfer of lactogenic immunity to canine parvovirus type 2 (CPV-2) from two bitches (A and B) to their offspring. At day 7 before parturition, bitches A and B had high serum antibody titers, which decreased rapidly within a few hours after parturition, in concomitance with the appearance of high HI titers in colostrum. Subsequently, the serum antibodies of the two dogs increased again, reaching approximately the initial titers. CPV-specific antibodies were observed in milk, with decreasing values, throughout the lactation period. The kinetics of MDA observed in the pups was consistent with the patterns of absorption and decline previously described.

Animals↗
PubMed2003

Modulation of pro-apoptotic (Bax) and anti-apoptotic (Bcl-2) gene expression in isolated porcine hepatocytes perfused within a radial-flow bioreactor after low-temperature storing.

Due to the scarcity of available human livers, porcine hepatocytes are currently being evaluated as a xenogeneic cell source for extracorporeal bioartificial liver (BAL). Hypothermic storage of isolated porcine hepatocytes could support stocking of cell-loaded bioreactors for BAL use and may provide bioreactors ready to be used at the patient's bedside. For the development of this technology, it is of utmost importance to ensure cell viability and differentiated functions after low-temperature storage and following warm reperfusion. We compared cell viability, functional activity and apoptosis in isolated porcine hepatocytes which were perfused within a radial-flow bioreactor (RFB), stored at 4 degrees C and then reperfused at 37 degrees C. RFBs were loaded with 8 x 10(9), > or = 90% viable hepatocytes at 37 degrees C for 3 h. RFBs were then flushed with 4 degrees C University of Wisconsin solution (UW) and subsequently stored for 24 h or 48 h. RFBs were then reperfused for 8 h with recirculating medium plus serum at 37 degrees C . Cytochrome P450 (CYP) activity was studied before and after cold storage by means of monoethylglycinexylide (MEGX) detection in the effluent medium, after repeated lidocaine injections. After reperfusion experiments, hepatocytes were harvested for total RNA isolation. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used in order to amplify specific mRNAs for Bcl-2 and Bax genes, by using appropriate primers; beta-actin primers were used as control. Total RNA was extracted by northern blotting analysis and for Bcl-2, Bax and beta-actin RNA messenger detection, RT-PCR amplification was used. Freshly isolated hepatocytes perfused into the RFB showed a progressive increase of MEGX while a loss in Bax expression was paralleled by an increase in Bcl-2 expression, in comparison to starting hepatocytes. After 4 degrees C storage and warm reperfusion, MEGX production was preserved in 24 h- and 48 h-stored bioreactors as well as a sharp increase of Bcl-2 and a decrease of Bax mRNAs. Our study suggests that refrigeration of hepatocyte-bioreactors is a suitable strategy to maintain both viability and function of isolated hepatocytes, for up to 48 h a time-length that is compatible with long-distance delivery of ready-to-use bioreactors.

Animals↗
PubMed2003

Morphostructural damage and the inhibition of bacterial adhesiveness of Staphylococcus aureus and Moraxella catarrhalis induced by moxifloxacin.

The aim of this study was to investigate the ability of moxifloxacin to interfere with the mechanism of bacterial adhesion and disrupt the morphological and structural integrity of bacteria. Three Staphylococcus aureus and three Moraxella catarrhalis strains were grown in the presence of 1/2-1/128 minimum inhibitory concentration (MIC) serial dilutions and incubated with human epithelial cells. A significant decrease in adhesion was observed from 1/2 MIC to 1/64 MIC for S. aureus, and from 1/2 MIC to 1/16 MIC for M. catarrhalis. The use of atomic force microscopy, a new technique capable of revealing surface structures in three-dimensional detail and at very high resolution, showed the rapid onset and time course of the sequence of disruptive morphostructural events following the incubation of both S. aureus and M. catarrhalis with sub-MICs of moxifloxacin. Our findings suggest that less than conventional MIC moxifloxacin concentrations may be effective in reducing bacterial adhesiveness and structural integrity on which the maintenance of bacterial activity depends.

Aza Compounds↗
PubMed2002

Daptomycin morphostructural damage in Bacillus cereus visualized by atomic force microscopy.

Daptomycin is a novel, rapidly bactericidal in vitro antibiotic that is under investigation for the treatment of serious Gram-positive infections. Although daptomycin appears to disrupt membrane function, the precise mechanism of action has not been fully elucidated. Atomic force microscopy (AFM) is an innovative technique that allows high-resolution visualization and digital image manipulation of cell surface structures in 3 dimensions without the use of photons and electrons. The aim of this study was to use AFM to investigate the morphostructural changes in Bacillus cereus that occur upon daptomycin administration. The effects of daptomycin at 4x and 8x the minimal inhibitory concentration were visualized during an 8-hour incubation period. Atomic force microscopy images showed aberrant bacterial surface formations, including flattening and shrinking of cells and leakage of cytoplasm through the membrane. In addition to structural changes, the destabilization of flagella was also observed. These results support previous data suggesting that daptomycin disrupts membrane function.

Anti-Bacterial Agents↗
PubMed2001

Endothelial cell adhesion on bioerodable polymers.

This paper presents the results of a preliminary screening of a new class of bioerodable polymers, partial esters of alternating copolymers of maleic anhydride and mono-methoxyoligoethyleneglycol vinyl ethers (PAM) for use in engineered vascular tissue. Different initial concentrations of PAM and human serum albumin (HSA) were spin-coated onto glass substrates and the surface properties of the resulting films and their relationship to endothelial cell adhesion was examined. An optimum PAM/HSA blend for use as the cell contact surface of a bioerodable scaffold was identified.

Journal Article↗
PubMed2001

Long-term expression of highly differentiated functions by isolated porcine hepatocytes perfused in a radial-flow bioreactor.

To overcome the limitations of standard hollow-fiber module in ensuring efficient cell perfusion and long-term expression of highly differentiated hepatocyte functions, we developed a novel bioreactor in which a three-dimensional hepatocyte culture system was perfused in radial-flow geometry. Isolated porcine hepatocytes were cultured for 2 weeks in recirculating serum-free tissue culture medium, in which NH4Cl and lidocaine were repeatedly added, and ammonia removal, urea synthesis, monoethylglycinexylide (MEGX) production, albumin secretion, Po2, Pco2, O2 consumption, and pH were measured thereafter. During the whole duration of the study, ammonia removal was paralleled by urea production, while MEGX concentration was constantly increased. Our results indicated that hepatocytes remained differentiated and metabolically active throughout the duration of the study. The radial-flow bioreactor allowed physiological contact between recirculating fluid and cells by equalizing the concentration of the perfusing components, including O2, throughout the module, suggesting a potential use of this configuration for extracorporeal liver support.

Albumins↗
PubMed2001

Spontaneous echo-contrast as an in vivo indicator of rheological imbalance in dilatative cardiomyopathy.

The aim of this study was to evaluate coagulative and hemorheologic assessment in patients with dilatative cardiomyopathy with or without spontaneous echo contrast (SEC). We studied 45 patients, 35 males and 10 females (mean age 72.1 +/- 9.2). We measured whole blood viscosity, plasmatic fibrinogen, prothrombin time (PT), activated partial thromboplastin time (aPTT), D-dimer and red cell morphology with Zipursky-Forconi method. Transthoracic and transesophageal echocardiography was performed in all patients to evaluate the presence of SEC in left atrium. We divided all the patients into two groups: the 1st group of 20 patients with SEC and Atrial Fibrillation (AF) in 80% of cases, and the 2nd group of 25 patients without SEC and AF in 31%. Our results show that in patients with SEC there is a statistically significant increase of whole blood viscosity and plasma fibrinogen in comparison with patients without SEC. Red cell morphology in all patients demonstrates a reversed EMI. D-Dimer, was out of the normal range in about 1/3 of the patients in both groups. An analysis of our results points out that in patients with SEC and AF, with a major risk factor for cardioembolic stroke, we have alterations of hemorheologic assessment with an increase of whole blood viscosity and fibrinogen that seems to be caused by an increase of red cells aggregability favoured by fibrinogen. Our conclusions are that SEC in patients with dilatative cardiomyopathy and AF is an important in vivo indicator of hemorheologic imbalance and an important marker for cardioembolic risk stroke evaluation.

Aged↗