Biomedical subjects

A Guzzetta

Publications and source records attributed to A Guzzetta.

At least 19 recordsLinked to original sources

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↗

PubMed2005

Distribution of sleep and wakefulness EEG patterns in 24-h recordings of preterm and full-term newborns.

The aim of this study was to evaluate the organisation of EEG patterns in 24-h recordings of preterm and near-term neonates. In particular, the distribution of the different EEG codes at different postmenstrual ages (PMA) and the variations of sleep-related EEG pattern organisation was studied, during day (8.00 a.m.-8.00 p.m.) and night (8.00 p.m.-8.00 a.m.) time. The age of appearance of different neonatal EEG patterns, previously described in literature for short lasting records, was confirmed in this 24-h study. The medium-voltage continuous EEG pattern (pattern "3") was less represented approaching term age, in coincidence with the appearance of the two low-voltage continuous patterns ("1" and "2"), which are also related to active sleep and wakefulness. Discontinuous pattern ("7") was also less represented with age, but in day-time only. The percentage of time occupied by this pattern, related to quiet sleep, was significantly higher during day-time hours, than at night.

Circadian Rhythm↗

PubMed2004

Can the Griffiths scales predict neuromotor and perceptual-motor impairment in term infants with neonatal encephalopathy?

AIMS: To examine the predictive value of early developmental testing for identifying neuromotor and perceptual-motor impairment at school age in children with neonatal encephalopathy (NE). METHODS: Eighty full term infants with NE were followed longitudinally. Where possible, children were tested on the Griffiths scales at 1 and 2 years and at 5-6 years, on the Touwen Examination, Movement ABC, and WPPSI. The relation between the Griffiths scores and later outcome measures was examined using correlation coefficients and sensitivity and specificity values. RESULTS: By 2 years, 25 children with cerebral palsy were too severely impaired to be formally assessed and remained so at 5-6 years. Abnormal Griffiths scores were obtained by 12% and 7% of the children at 1 and 2 years respectively. At 5-6 years, 33% had poor Movement ABC scores and 15% poor WPPSI scores. The highest correlation between Griffiths scores and the outcome measures was for the Movement ABC (0.72), although this accounted for only 50% of the variance. Sensitivity scores for the Movement ABC were below 70% but specificity was 100%. CONCLUSIONS: A poor score on the Griffiths scales at 1 and/or 2 years is a good predictor of impairment at school age. However, a normal score in the early years cannot preclude later neurological, perceptual-motor, or cognitive abnormalities.

Brain Diseases↗

PubMed2004

Visual function at school age in children with neonatal encephalopathy and low Apgar scores.

OBJECTIVE: To assess different aspects of visual function at school age in children who suffered from neonatal encephalopathy. METHOD: Thirty nine full term infants with neonatal encephalopathy, low Apgar scores, and early neonatal imaging were studied using a battery of tests assessing different aspects of visual function (crowding acuity, stereopsis, visual fields) at school age. The results were compared with brain magnetic resonance imaging (MRI) findings and, when possible, with the results of the assessment of visual function performed at 5 and 12 months, available in 24 of the 39 children examined at school age. RESULTS: Sixteen of the 39 children (41%) had abnormal results at school age in at least one of the visual tests used. Seven of these 16 were untestable on all tests. The remaining 23 children (59%) had normal results. CONCLUSIONS: The presence and severity of visual impairment was related to the severity of brain lesions. Moderate or severe basal ganglia lesions and severe white matter changes were always associated with abnormal visual function. Infants with normal MRI, minimal basal ganglia lesions, and minimal or moderate white matter involvement tended to have normal vision. It was also found that the assessment of visual function performed in the first year was a reliable indicator of visual function at school age. With two exceptions, the results on the 5 month visual assessment were predictive of visual outcome at school age. In the remaining two cases, a normal visual outcome at 5 years was associated with visual abnormalities at 5 months but these had already normalised by the age of 1 year.

Apgar Score↗

PubMed2003

General movements detect early signs of hemiplegia in term infants with neonatal cerebral infarction.

Background. Studies have reported that infants with hemiplegia of congenital origin may have a period between birth and up to 12 months when clinical signs of hemiplegia are not evident. The aim of this study was to establish whether the assessment of general movements (GMs) may help in the earlier detection of signs of hemiplegia. Subjects and Methods. Eleven infants with cerebral infarction on brain MRI, and eleven normal controls were enrolled in the study. Quality of GMs was assessed from videotapes between 3 and 6 weeks and between 9 and 16 weeks. Neurological outcome was evaluated at least at two years. Results. Seven of the 11 infants had an assessment performed between 3 and 6 weeks: abnormal GMs were observed in all the infants who developed hemiplegia, but one child had abnormal GMs and a normal outcome. All 11 infants had a scorable assessment between 9 and 16 weeks. In all a specific type of GMs, fidgety movements (FMs), were predictive of neurological outcome. The presence of early asymmetries at both 3 - 6 and 9 - 16 weeks was also significantly associated with later signs of hemiplegia. Conclusions. The assessment of GMs after the neonatal period appears to be very useful in the early identification of hemiplegia in infants with cerebral infarction. Whilst the prediction of hemiplegia should be possible from early neonatal MRI brain scans, this facility is not always available. Observation of GMs is a bedside clinical approach that allows confirmation of early prediction from MRI, early rehabilitation if needed and reassurance that neurological outcome will be good where that is appropriate.

Cerebral Infarction↗

PubMed2003

Neonatal cerebral infarction and visual function at school age.

OBJECTIVE: To assess various aspects of visual function at school age in children with neonatal cerebral infarction. PATIENTS AND METHODS: Sixteen children born at term, who had cerebral infarction of perinatal onset on neonatal magnetic resonance imaging (MRI) were assessed using a battery of visual tests. This included measures of crowding acuity (Cambridge Crowding Cards), stereopsis (TNO test), and visual fields. The results of the visual assessment were compared with the type and the extent of the lesion observed on neonatal MRI. RESULTS: Only six of the 16 children (28%) had some abnormalities of visual function on these tests. Visual abnormalities were more common in children with more extensive lesions involving the main branch of the middle cerebral artery and were less often associated with lesions in the territory of one of the cortical branches of the middle cerebral artery. The presence of visual abnormalities was not always associated with the involvement of optic radiations or occipital primary visual cortex. Abnormal visual fields were only found in children who also developed hemiplegia. CONCLUSIONS: Abnormality of visual function is not common in children who had neonatal infarction and, when present, tends to be associated with hemiplegia and more extensive lesions.

Cerebral Infarction↗

PubMed2002

Visual function and EEG reactivity in infants with perinatal brain lesions at 1 year.

The aim of this study was to examine the correlation between EEG, visual, and brain MRI findings in 19 term infants with perinatal brain lesions. All 19 had their visual acuity and visual fields assessed and had an EEG and a brain MRI performed at 1 year of age. Four of the five infants with normal optic radiations and occipital cortices on MRI had normal vision. Involvement of optic radiations and occipital cortices was only associated with visual abnormalities in eight of 14 infants. The correlation between visual abnormalities and EEG findings was stronger. All infants with a completely normal EEG from the posterior regions had normal vision and all those with an EEG non-reactive to eye closure had visual abnormalities, irrespective of MRI data. A reactive EEG with other abnormal features (such as spikes, rapid or slow activities) was accompanied by abnormal vision in five of eight participants. Results suggest that there is a better correlation between visual function and EEG activity than between visual function and involvement of the classical visual areas of the occipital cortex and optic radiations on brain MRI at 1 year of age.

Action Potentials↗

PubMed2001

Visual function in children with hemiplegia in the first years of life.

The aim of this study was to evaluate the incidence of visual function abnormalities in children with infantile hemiplegia, and the relation between visual abnormalities and type of lesion, as shown by brain MRI. Visual function was tested (grating acuity, visual field size, binocular optokinetic nystagmus [OKN], and ocular movements) in a group of 47 children with congenital or early acquired hemiplegic cerebral palsy (mean age 25 months, range 8 to 52 months). The cohort was subdivided into four groups according to MRI findings: brain malformations (n=5), abnormalities of the periventricular white matter (n=20), cortical-subcortical lesions (n=16), and non-progressive postnatal brain injuries (n=6). More than 80% of the children showed abnormal results in at least one visual test: acuity was the least impaired function, while visual field and OKN were abnormal in more than 50% of the cohort. No specific correlation could be identified between the type and timing of the lesions and visual function. Unlike adults with stroke, visual field defects were not always related to contralateral damage in the optic radiations or in the visual cortex. These results indicate that visual abnormalities are common in children with hemiplegia, and that they cannot always be predicted by MRI. All children with hemiplegia need a detailed assessment of visual function.

Age Factors↗

PubMed2001

Visual disorders in children with brain lesions: 1. Maturation of visual function in infants with neonatal brain lesions: correlation with neuroimaging.

In the last two decades there has been a considerable increase in the understanding of visual maturation in the young infant and it has been possible to develop methods for testing visual function that are applicable in the neonatal period and early infancy. Several studies have reported that various aspects of visual function, such as visual acuity, visual fields and optokinetic nystagmus are often impaired in infants with brain lesions of antenatal and perinatal onset. We report our experience with such infants and a more general review of the literature on the maturation of visual function in the first years after birth in normal and brain damaged children.

Brain Damage, Chronic↗

PubMed2001

Visual disorders in children with brain lesions: 2. Visual impairment associated with cerebral palsy.

Disorders of visual function are a common finding in children with cerebral palsy. In some cases they are secondary to ophthalmologic abnormalities such as cataract or retinopathy, but more often they are due to damage of the central visual pathway. We review the literature on the prevalence and distribution of visual abnormalities in children with cerebral palsy and their relation to cognitive, motor and emotional development.

Cerebral Palsy↗

PubMed2001

Neurologic examination in infants with hypoxic-ischemic encephalopathy at age 9 to 14 months: use of optimality scores and correlation with magnetic resonance imaging findings.

OBJECTIVES: To evaluate whether a structured and scorable neurologic examination (The Hammersmith Infant Neurological Examination) correlates with early magnetic resonance imaging findings in a group of infants with hypoxic-ischemic encephalopathy (HIE) and whether the scores of this assessment can predict the locomotor function in these children. STUDY DESIGN: A total of 53 term infants fulfilling the criteria for HIE underwent scanning within 4 weeks from delivery with a 1 Tesla HPQ magnet. The scores from the neurologic examination performed between 9 to 14 months were correlated to the neonatal magnetic resonance imaging findings and to the maximal locomotor function defined at the ages of 2 and 4 years. RESULTS: The scores were always optimal in the infants with normal or minor neonatal magnetic resonance imaging findings. The lowest scores were associated with severe basal ganglia and white matter lesions. All the infants who had a global score between 67 and 78 at 1 year were able to walk independently at 2 years and without restrictions at 4 years. Scores between 40 and 67 were associated with restricted mobility and scores <40 with severely limited self-mobility at 2 and 4 years. CONCLUSIONS: The use of a standardized neurologic optimality scoring system gives additional prognostic information, easily available in the clinic, on the severity of the functional motor outcome in infants with HIE.

Female↗

PubMed2001

[Role of neurologic assessment in the evaluation and prognosis of full-term newborns with asphyxia].

Hypoxic-ischaemic encephalopathy, the clinical neurological syndrome that follows birth asphyxia, is one of the main causes of neurological sequelae in term newborns. Despite the advent of new imaging and neurophysiological techniques in the last two decades, the value of the neurological assessment of the newborn has not been reduced. The possibility to perform easily serial neurological evaluations allows a detailed and non-invasive follow up of the early developmental processes, providing reliable prognostic information. In this paper we report our experience and a more general review of the literature on the prognostic value of the neurological assessment in term newborns with hypoxic-ischaemic encephalopathy.

Asphyxia Neonatorum↗

PubMed2000

The formation and mechanism of multimerization in a freeze-dried peptide.

Atrial natriuretic peptide (ANP) is a peptide with 25 amino acid residues (hANP 4-28) and one intra-chain disulfide bond. We used the size-exclusion chromatography (SEC), sodium dodecyl sulfate in polyacrylamide gel electrophoresis (SDS-PAGE), and reversed-phase liquid chromatography with electrospray mass spectrometry (LC-MS) methods to examine the freeze-dried products of ANP to determine the types, sizes, and amounts of the multimer formation in different stability protocols (by varying the conditions with lyophilization cycles, excipients, storage temperatures, and times). Under the non-annealing lyophilization cycle or lyophilization with high concentration of bulking agent (mannitol), multimer formation increased with increasing storage times. Two kinds of multimers were observed; the major portion is reducible and the minor portion is non-reducible. The reducible multimers are disulfide-linked multimers as determined by LC-MS. The non-reducible multimer was mainly a dimer, possibly linked by a covalent bond between the side chain of tyrosine in one molecule and the dehydroalanine intermediate in another molecule, based on the evidences of the mass of the non-reducible dimer along with the elution position in SEC, and the change of the UV spectrum in the aromatic region. The analysis of degradants suggests that the mechanism start from an beta-elimination of disulfide linkage to form a free thiolate ion (HS-) and a dehydroalanine-type peptide intermediate. The HS- then catalyzed ANP to form the disulfide-linked multimers. The dehydroalanine-type ANP intermediate then reacted with another ANP molecule to form a non-disulfide-linked dimer through reaction with the side chain of tyrosine. These results suggest that the source of multimer formation be initiated by phase transition (from amorphous to crystalline phase) either in the freeze-dried process or during storage. That phase change may induce a drastic change in pH and moisture to damage the peptide. The detailed mechanism and the kinetics of ANP multimerization are discussed. The formation of the multimers was diminished by using the thermal treatment (the annealing step) with a proper ratio of mannitol to ANP peptide in the lyophilization, and/or increase of the acetate buffer concentration in the formulation.

Amino Acid Sequence↗

PubMed2000

Correlation between visual function, neurodevelopmental outcome, and magnetic resonance imaging findings in infants with periventricular leucomalacia.

AIM: To evaluate the correlation between visual function and neurodevelopmental outcome in children with periventricular leucomalacia at 1 and 3 years. METHOD: Visual acuity, visual field, ocular motility, and optokinetic nystagmus were tested in 29 infants with periventricular leucomalacia by brain magnetic resonance imaging. All infants also had a structured neurological examination and a Griffiths developmental assessment. RESULTS: 21 of the infants showed at least one abnormality of visual function. The degree of visual impairment-that is, the number of visual tests showing abnormal results-correlated well with the results on developmental assessment at both ages. CONCLUSION: Multivariate analysis showed that visual impairment was the most important variable in determining the neurodevelopmental scores of these infants, more than their motor disability and the extent of their lesions on magnetic resonance imaging.

Child, Preschool↗

PubMed1999

Neonatal neurological examination in infants with hypoxic ischaemic encephalopathy: correlation with MRI findings.

Neurological examination and magnetic resonance imaging were performed in the neonatal period in 58 full-term infants who presented with hypoxic-ischaemic encephalopathy. The aim of this study was to evaluate the patterns of neurological abnormalities and their correlation to brain lesions on MRI. The prognostic value of the neurological examination performed at different times in the neonatal period was also evaluated. Our results showed that specific clinical patterns can be observed in infants with HIE and these can be related to the pattern of lesion on brain MRI. In particular, while infants with normal MRI or minimal changes tend to show only minor tone abnormalities after the first week of life, infants with more severe lesions such as basal ganglia lesions show persistent and diffuse neurological abnormalities. Infants with white matter changes but intact basal ganglia show a different clinical pattern with improved sucking reflex and behaviour and less severe tone abnormalities. Our results also suggested that the neurological examination performed after the second week of life is a reliable indicator of outcome in these infants.

Asphyxia Neonatorum↗

PubMed1999

Visual function in term infants with hypoxic-ischaemic insults: correlation with neurodevelopment at 2 years of age.

AIMS: To determine if there is any association between the findings of visual assessment performed at the age of 5 months and neurodevelopmental outcome at the age of 2 years in children who have sustained hypoxic-ischaemic insults. METHODS: Twenty nine term infants with hypoxic-ischaemic encephalopathy and/or brain lesions on neonatal magnetic resonance imaging (MRI) were prospectively evaluated. At 5 months of age all the infants had their visual function assessed using the Atkinson Battery of Child Development for Examining Functional Vision, which includes the assessments of optokinetic nystagmus (OKN), acuity, visual fields, fixation shift and phase and orientation reversal visual evoked potentials. At 2 years of age the children had a structured neurological evaluation and a Griffiths developmental assessment. RESULTS: There was good correlation between the extent of the early detected visual impairment and both neuromotor and global development. Children with more than three out of five abnormal visual tests at 5 months of age tended to have abnormal neurological examination results and abnormal developmental quotients. Children with three or fewer abnormalities tended to have developmental quotients in the normal range; the level of their performance, however, was still related to the number of visual tests passed. CONCLUSIONS: Individual visual tests can provide important prognostic information. While abnormal OKN and acuity were always associated with abnormal outcome, normal results on visual evoked potentials and fixation shift tended to be associated with normal outcome.

Brain↗

PubMed1998

Peptides derived from the complementarity-determining regions of anti-Mac-1 antibodies block intercellular adhesion molecule-1 interaction with Mac-1.

Peptides or small molecules that can block the interaction of the integrin Mac-1 with its receptor, intercellular adhesion molecule-1 (ICAM-1), have not previously been developed. We studied this interaction by measuring the adherence of ICAM-1-expressing Chinese hamster ovary (CHO) cells to immobilized, purified Mac-1. Nucleotide sequence information was obtained for the complementarity determining regions (CDRs) of three antibodies (44aacb, MY904, and 118.1) shown to block Mac-1-mediated cell adherence. Peptides were synthesized based on the predicted amino acid sequences of the CDRs and tested for the ability to block cell adhesion to Mac-1. Peptides derived from CDR1 of 44aacb, CDR2 of 118.1, and CDRs 1 and 3 of MY904 heavy chains were found to possess blocking activity at 10-100 muM. This may indicate that one or two CDRs contribute disproportionately to the antibody binding affinity. The binding of ligands to Mac-1 has been shown to require a region of the alpha-chain known as the I- or A-domain. We have recombinantly produced Mac-1 I-domain, and show that it is also capable of supporting the adherence of ICAM-1-expressing CHO cells. The adherence of ICAM-1-CHO cells to the I-domain is inhibited by 44aacb and 118.1 and by the CDR peptides from 44aacb and 118.1. By using phage display of peptide libraries based on the 118.1 CDR peptide with five residues randomized, we were able to identify a novel peptide inhibitor of Mac-1 with substitutions at all five positions. These peptides provide lead structures for development of Mac-1 antagonists.

Amino Acid Sequence↗