Search PubMed⌕ Search

Biomedical subjects

M Ceccarelli

Publications and source records attributed to M Ceccarelli.

At least 19 recordsLinked to original sources
PubMed2006

Chromosome endoreduplication as a factor of salt adaptation in Sorghum bicolor.

Nuclear DNA amounts were measured by Feulgen cytophotometry in Sorghum bicolor cv. 610 plants early exposed to 150 mM NaCl, a treatment known to induce an increased tolerance to salinity in plants carrying this genotype. In salt-treated plants, the percentages of 8C, 16C, and 32C nuclei in roots in the primary state of growth were 21.9%, 13.3%, and 4.3%, respectively. By contrast, in nonsalinized plants, only 3.5% of the nuclei had an 8C content and no higher DNA contents were observed. The salt treatment induced chromosome endoreduplication during the differentiation of cells in the root cortex, where 41.2% of the cells displayed a DNA content higher than 4C (versus 1.3% in control plants). No enhancement of endopolyploidy was observed in cells of the root vascular cylinder or the leaves of the salt-treated plants. In another S. bicolor genotype (DK 34-Alabama), noncompetent for salt adaptation, the same NaCl treatment did not induce chromosome endoreduplication in root cortex cells. Endopolyploidy may be considered as a part of the adaptive response of S. bicolor competent genotypes to salinity.

Adaptation, Physiological↗
PubMed2005

The microscopic switching mechanism of a [2]catenane.

We apply numerical simulations at an all-atom level to investigate the switching mechanism of a [2]catenane, a prototype of a molecular machine. This system is able to switch reversibly between two different stable states, upon external stimuli, with a time scale ranging from microseconds up to milliseconds, well over the typical domain of molecular dynamics (MD) computer simulations. However, combining a strategy recently developed for investigating rare events with ordinary MD, we are able to unravel the microscopic mechanism of the conformational rearrangements involved in the switching process, including dynamical effects. Along the path that connects the product and reactant state, we find several intermediate states characterized by pi-pi stacking interactions and hydrogen bonds. Moreover, counterions interact strongly with the system in a correlated way, in agreement with recent static calculations performed on [2]rotaxanes.

Journal Article↗
PubMed2005

Cytogenetics of Triticum x Dasypyrum hybrids and derived lines.

Genomic in situ hybridization was used to study Triticum x Dasypyrum wide hybrids and derived lines. A cytogenetic investigation was carried out in progenies of (i) amphiploids derived from T. turgidum var. durum (T. durum; 2n = 14; genomes AABB) x D. villosum (2n = 14; genome VV), (ii) three-parental hybrids (T. durum x D. villosum) x T. aestivum (2n = 42, genomes A'A'B'B'D'D'), and (iii) T. aestivum aneuploid lines carrying D. villosum chromosomes or chromatin. The amphiploids derived from T. durum x D. villosum showed a stable chromosomal constitution, made up of 14 V chromosomes, 14 chromosomes carrying the wheat A genome and 14 chromosomes carrying the B genome. High karyological instability was observed in the progenies of three-parental hybrids ([T. durum x D. villosum] x T. aestivum). Plants having the expected 14 A chromosomes, 14 B chromosomes, 7 D chromosomes, and 7 V chromosomes were rather rare (4.5%). Many progeny plants (45.5%) had the hexaploid wheat genome with 42 chromosomes and lacked any detectable D. villosum chromatin. Other plants (50%) had 14 A chromosomes and 14 B chromosomes, plus variable numbers of D and V chromosomes, the former being better retained than the latter in most cases. Some T. aestivum lines carrying D. villosum chromosomes or chromatin, as the result of addition, substitution, or recombination events or even a combination of these karyological events, were found to be stable. Other lines were unstable, and these lines carried 1V, 3V, or 5V chromosomes or their portions. Substitution or recombination events where 1V chromosomes were involved could concern the homeologous counterparts in both the A and B and D genomes of wheat. No line could be recovered where the shorter arm of 3V chromosomes was present. Changes in the morphology and banding pattern of V chromosomes were observed in hybrids that did not carry the entire D. villosum complement. By comparing the results of our cytogenetic analyses with certain phenotypic characteristics of the lines studied, genes for discrete traits could be assigned to specific V chromosomes or V chromosome arms. From the frequency of V chromosomes that were involved in chromatin exchanges with or substituted for one of their homeologous counterparts in the A, B, and D wheat genomes, it was inferred that D. villosum belongs to the same phyletic lineage as T. urartu (donor of the A genome of wheat) and Aegilops speltoides (B genome), and that Ae. squarrosa (D genome) diverged earlier from D. villosum.

Chromosomes, Plant↗
PubMed2001

Dynamics of hydration in hen egg white lysozyme.

We investigate the hydration dynamics of a small globular protein, hen egg-white lysozyme. Extensive simulations (two trajectories of 9 ns each) were carried out to identify the time-scales and mechanism of water attachment to this protein. The location of the surface and integral water molecules in lysozyme was also investigated. Three peculiar temporal scales of the hydration dynamics can be discerned: two among these, with sub-nanosecond mean residence time, tau(w), are characteristic of surface hydration water; the slower time-scale (tau(w) approximately 2/3 ns) is associated with buried water molecules in hydrophilic pores and in superficial clefts. The computed tau(w) values in the two independent runs fall in a similar range and are consistent with each other, thus adding extra weight to our result. The tau(w) of surface water obtained from the two independent trajectories is 20 and 24 ps. In both simulations only three water molecules are bound to lysozyme for the entire length of the trajectories, in agreement with nuclear magnetic relaxation dispersion estimates. Locations other than those identified in the protein crystal are found to be possible for these long-residing water molecules. The dynamics of the hydration water molecules observed in our simulations implies that each water molecule visits a multitude of residues during the lifetime of its bound with the protein. The number of residues seen by a single water molecule increases with the time-scale of its residence time and, on average, is equal to one only for the water molecules with shorter residence time. Thus, tau(w) values obtained from inelastic neutron scattering and based on jump-diffusion models are likely not to account for the contribution of water molecules with longer residence time.

Animals↗
PubMed1999

A family of dispersed repeats in the genome of Vicia faba: structure, chromosomal organization, redundancy modulation, and evolution.

A family of repeated DNA sequences of about 1200 bp in length and bordered by well-conserved, 18 bp inverted repeats (VfB family) was found in the nuclear genome of Vicia faba. The structure, chromosomal organization, redundancy modulation and evolution of these sequences were investigated. They are enriched in A+T base pairs (about 40% G+C) and lack any obvious internally repeated motif. A 64%-73% nucleotide sequence identity was found when pairwise comparisons between VfB sequences were carried out (average 69%). Direct repeats were not found to flank the inverted repeats that border these DNA sequences. The results obtained by hybridizing VfB repeats to Southern blots of V. faba genomic DNA digested with EcoRI indicated that these DNA elements are interspersed in the genome. The appearance of bands in these Southern blots and comparison of the structure of the sequences that flank different VfB elements showed that these repeats might be part of other, longer repeated DNA sequences. A high degree of dispersion throughout the genome was confirmed by cytological hybridization, which showed VfB sequences to be scattered along the length of all chromosomes and to be absent or rare only at heterochromatic chromosomal regions. These sequences contribute to intraspecific alterations of genomic size. Indeed, dot-blot hybridizations proved that their redundancy, which is positively correlated with the overall amount of nuclear DNA in each accession, varies between V. faba land races (27x10(3)-230x10(3) copies per 1C DNA). Southern blot hybridization of VfB repeats to restriction endonuclease-digested genomic DNAs of V. faba, V. narbonensis, V. sativa, Phaseolus coccineus, Populus deltoides, and Triticum durum revealed nucleotide sequence homology of these DNA elements, whatever the stringency conditions, only to the DNAs of Vicia species, and to a reduced extent to the DNAs of V. narbonensis and V. sativa compared with that of V. faba. It is concluded that VfB repeats might be descended from mobile DNA elements and contribute to change genomic size and organization during evolution.

Base Composition↗
PubMed1999

Amount and organization of the heterochromatin in Olea europaea and related species.

The amount and spatial organization of the heterochromatin in nuclei of the shoot meristem and the frequency in the nuclear DNA of sequences belonging to a family of tandem repeats were investigated in cultivars of Olea europaea and related species. Significant differences between Olea species and between cultivars of O. europaea were observed: (i) in the spatial organization of the heterochromatin in interphase nuclei as determined by the number and surface area of the chromocentres; (ii) in genome size; and (iii) in the amount of condensed chromatin as measured by cytophotometry carried out at different thresholds of optical density. DNA elements belonging to a family of tandem repeats about 80 bp in length (OeTaq80 repeats) were isolated from the genomic DNA of an olive cultivar. It was shown: (i) by nucleotide sequence comparisons, that these repeats display variability in structure even within the same array, where different elements may share no more than 74% homology; (ii) by in situ hybridization, that OeTaq80-related DNA sequences are mainly localized in the heterochromatin at the chromosome ends; (iii) by dot-blot hybridization experiments, that these sequences are highly represented in the genome of all the olive cultivars and the majority of Olea species studied, and that their frequency may differ significantly even between olive cultivars; and (iv) by calculating the copy number of OeTaq80-related sequences per haploid (1C) genome, that the redundancy of these DNA elements may differ significantly between the genomes tested. It is suggested that the inter- and intraspecific changes in the nuclear and genomic traits observed can contribute to the understanding of the phylogenetic relationships between Olea species and in defining parameters to be exploited in varietal identification within cultivated olives.

Base Sequence↗
PubMed1997

Platelet serotonin transporter in coeliac disease.

We investigated a peripheral serotonergic marker, i.e. platelet tritiated imipramine (3H-IMI) binding sites, which are part of the 5-HT transporter complex similar to that present in the brain, in 20 patients affected by coeliac disease (CD), as compared with 20 healthy controls. Platelet membranes and 3H-IMI binding were carried out according to a standardized protocol. The results showed that coeliac patients had significantly lower 3H-IMI binding sites than controls. This finding would suggest the presence of a dysfunction at the level of the 5-HT transporter that might underline the psychic disturbances frequently observed in coeliac patients.

Adolescent↗
PubMed1997

[Atypical and incomplete Kawasaki disease].

Kawasaki Disease (KD) is an acute systemic vasculitic disorder of childhood of unknown etiology. Initially KD was thought to be a benign disease, but later on it became obvious that cardiac manifestations are present in about 25-30% of patients and lead to death in about 0.5-2% of them. An early diagnosis and treatment are important to avoid an unfavourable prognosis. In recent years, a number of publications described patients in which the diagnosis was delayed because they did not fulfil the required criteria of KD. These forms of KD are known as atypical or incomplete KD. The aim of this work is to describe two cases of atypical KD observed at the Department of Pediatrics, University of Pisa during the year 1992.

Aspirin↗
PubMed1995

FokI DNA repeats in the genome of Vicia faba: species specificity, structure, redundancy modulation, and nuclear organization.

Tandemly repeated DNA sequences about 60 bp in length, which may be isolated by digestion with FokI restriction endonuclease, were studied by means of molecular and cytological hybridization in Vicia faba and other Vicia species. The results obtained can be summarized as follows: (i) FokI repeats are almost species specific to V. faba, since they hybridize to a minimum extent to genomic DNA of only two out of five related species; (ii) these tandemly repeated elements display variability in structure even within one and the same array, where different repeats may share not more than 71% homology; (iii) their redundancy in the genome of V. faba is remarkably high and varies largely between land races (copy numbers per haploid, 1C, genome range from 21.51 x 10(6) to 5.39 x 10(6)); (iv) FokI repeats are clustered in differing amounts in each subtelocentric pair of the chromosome complement and are missing or present in a nondetectable amount in the submetacentric pair; (vi) chromosome regions that bear these repeats associate closely to varying degrees in interphase nuclei. These results are discussed in relation to possible functional roles that tandemly repeated DNA sequences such as the FokI elements might play.

Base Sequence↗
PubMed1995

Varicella in immunocompetent children in the first two years of life: role of treatment with oral acyclovir. Italian Acyclovir-Chickenpox Study Group.

An open multicenter study has been carried out to evaluate efficacy and tolerability of oral acyclovir in the treatment of varicella in immunocompetent patients in the first two years of life. Fifty-three children aged 3-24 months received acyclovir at 80 mg/Kg/day in four divided doses for 4 to 6 days; 24 of them were treated in the first 24 hours following disease onset, while the remaining 29 patients were enrolled within 48 hours. The assessment of evolution of disease signs and symptoms showed a rapid resolution of fever, itching and other constitutional symptoms, with interruption of vesicle formation and acceleration of cutaneous healing processes. No statistically significant differences have been demonstrated as to disease progression between patients treated in the first 24 hours, when compared with subjects receiving acyclovir in the following 24 hours. Acyclovir confirmed its excellent clinical and laboratory safety profile. By acting favorably on both the duration and severity of disease signs and symptoms, acyclovir treatment should be recommended in young children and infants with varicella, since a higher incidence of severe and complicated disease has been observed in these patient groups.

Acyclovir↗
PubMed1995

[Intestinal intussusception in children].

Enteric intussusception is one f the most frequent causes of acute abdomen in early childhood, with an incidence of 1.3-2/1000 children born and higher frequency from the third to the twelfth month. Primary intussusception is related to predisponsing factors such as peristalsis disorders or Peyer's patch hypertrophy induced by viral infection. Secondary intussusception is due to organic injury in the intestinal wall. The most involved sites are the terminal ileum and the ileocecum, the most frequent type is ileocolic intussusception. Many clinical forms exist, including acute enteric intussusception with its pathognomonic triad intermittent abdominal pain, emesis and rectal bleeding and the atypical form with a neurological presentation, where sopor, myosis and muscular atonicity are dominating, Intussusception can also present in a subacute or chronic form with a slow and apsecific onset. In a retrospective investigation we examined 30 cases of intussusception in children hospitalized at the Pediatric Clinic of Pisa from the 1960s up to today. Our patients (16 males and 14 females) were aged between one month and two years. Clinical presentations resulted in; typical forms (60%), atypical forms (16%), subacute forms 13%) and recurrent forms (10%). Clinical suspicion was confirmed either by the presence of blood observed during rectal exploration, which is a pathognomonic sign, or by the opaque enema which led to recovery by means of hydrostatic reduction in 40% of the cases. The remaining patients (60%) underwent surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen, Acute↗
PubMed1995

[Description of two cases of Munchausen syndrome by proxy].

The Munchausen syndrome by proxy, or Polle syndrome can be considered as a form of child abuse in which parents falsify or even produce a real pathology in their children submitting them to frequent hospitalizations and pointless medical examinations. The authors discuss two cases and emphasize the importance of an early identification of these cases to avoid psychical impairments that inevitably stem from this "new" form of child abuse.

Child↗
PubMed1995

[Apparent life threatening events (ALTE): prelude to SIDS? Description of 14 cases].

The peak incidence of the Sudden Infant Death Syndrome (SIDS) is between 2 and 4 months of age. Its pathology is extremely heterogenous, infection, hypoxia and many others factors are all implicated. We examine here the possible relation between SIDS and Apparent Life Threatening Event (ALTE). We describe 14 cases that we have observed to establish a primary connection between these two situations and to identify a risk-group for an accurate follow-up.

Age Factors↗
PubMed1994

[Bacterial meningitis. Review of literature and retrospective study of 208 cases observed].

Bacterial meningitis is a particularly dangerous infection of the central nervous system involving quite a number of mortal cases and frequent neurological sequelae. Etiology varies in relation to the patient's age. In the first 2 months of life Streptococcus B, Listeria monocytogenes, Escherichia coli and other Gram negative enteric bacilli are more frequently isolated while in older children Haemophilus influenzae, Neisseria meningitidis and Streptococcus pneumoniae are more common. Clinical symptoms take a different form according to the patient's age: symptoms of a general kind prevail in the first 2 months of life while in older children signs of meningeal irritation predominate. In a review of the survey of cases of bacterial meningitis observed at the Clinica Pediatrica in Pisa from 1970 to July 1993, with a retrospective research, 208 patients have been examined, considering age, etiology, clinical course especially observing the course of temperature, liquor characteristics, normalisation of the index of phlogosis, mortality and neurological sequelae. In the last ten years the availability of 3rd generation cephalosporin has provided the possibility of comparing two groups of patients of an age ranging between 1 month and 14 years. Twenty cases were treated with ampicillin and chloramphenicol and 30 cases with cephalosporins the evaluation made considering the course of temperature, the normalization of the liquor index has revealed a more favourable clinical course in the second group of patients.

Adolescent↗
PubMed1993

[Diencephalic syndrome. Case report and review of literature].

We report the case of a twenty-three month old, normally eating child, affected by organic macies and severe dystrophy. After the negative response of blood and laboratory examinations let us exclude a malabsorption syndrome, only the performance of neuro-radiologic exams showed evidence of a subthalamic tumor as the cause of a "Diencephalic syndrome". Diencephalic syndrome or Russel's syndrome is a diencephalic tumor induced disease, which sets in the first three years of life. The disease clinical markers are a severe emaciation with appetite preservation and absence or very scarce evidence of any telltale neurological sign. the tumoral histo-pathology most frequently shows a low grade of malignancy astrocytoma, whose eradication is very often difficult because of the particular anatomic site. Choice treatment includes an excisional biopsy associated to chemotherapy and to radiotherapy.

Astrocytoma↗
PubMed1992

The unbalanced offspring of the male carriers of the 11q;22q translocation: nondisjunction at meiosis II in a balanced spermatocyte.

Carriers of the standard translocation t(11;22) (q23.3;q11.2) produce only one type of unbalanced offspring, a tertiary trisomy resulting into the karyotype 47,XX or XY, +der(22)t(11;22)(q23.3;q11.2), usually derived from the mother. The exception is one single patient 47,XY,t(11;22)(q23.3;q11.2), +der(22)t(11;22) (q23.3;q11.2)pat. We report a second case with the same karyotype, also of paternal origin. Thus, the rare unbalanced offspring of a carrier father (only 5 cases known) may receive a supernumerary der(22), as a consequence of tertiary trisomy, but also as a consequence of nondisjunction at meiosis II of a balanced spermatocyte.

Chromosome Banding↗
PubMed1992

Clinical and electrophysiological reports in a case of early onset myotonia congenita (Thomsen's disease) successfully treated with mexiletine.

A sporadic event of myotonia congenita in a infant admitted to the Paediatric Clinic for frequent crises of apnoea, cyanosis, vomiting and difficult feeding is reported. EMG analysis was consistent with the dominant variety of myotonia congenita. Mexiletine therapy showed excellent results in reducing myotonic activity. It is worthwhile stressing that early symptoms may go unnoticed or may be misinterpreted and that information on the genetic form of the disease can be obtained also from the EMG analysis through a repetitive stimulation test.

Electromyography↗