Biomedical subjects

D Monteleone

Publications and source records attributed to D Monteleone.

8 recordsLinked to original sources

PubMed2001

Clustered DNA damages induced by high and low LET radiation, including heavy ions.

Clustered DNA damages--here defined as two or more lesions (strand breaks, oxidized purines, oxidized pyrimidines or abasic sites) within a few helical turns--have been postulated as difficult to repair accurately, and thus highly significant biological lesions. Further, attempted repair of clusters may produce double strand breaks (DSBs). However, until recently, there was no way to measure ionizing radiation-induced clustered damages, except DSB. We recently described an approach for measuring classes of clustered damages (oxidized purine clusters, oxidized pyrimidine clusters, abasic clusters, along with DSB). We showed that ionizing radiation (gamma rays and Fe ions, 1 GeV/amu) does induce such clusters in genomic DNA in solution and in human cells. These studies also showed that each damage cluster results from one radiation hit (and its track), thus indicating that they can be induced by very low doses of radiation, i.e. two independent hits are not required for cluster induction. Further, among all complex damages, double strand breaks comprise--at most-- ~20%, with the other clustered damages being at least 80%.

Cells, Cultured↗

PubMed1996

Automatic semantic facilitation in Alzheimer's disease.

To explore the nature of semantic deficit in Alzheimer's disease patients (AD patients) we compared two tasks that are known to be very different with respect to the type of attentional demand and conscious effort they require: lexical decision (automatic) in a semantic priming paradigm and semantic relatedness judgements (intentional). In order to minimise post-lexical facilitation we devised a semantic priming experiment that met an automatic condition as much as possible, and we selected patients without severe word recognition deficits. AD patients showed reduced accuracy in the semantic relatedness judgements as compared to controls. Some effect of priming was found, but this was weaker than in normals. AD patients also differed from controls on targets preceded by a nonlinguistic prime (neutral condition) where their reaction times were slower as compared to neutral condition.

Aged↗

PubMed1995

Low serum tryptophan to large neutral amino acids ratio in idiopathic infantile autism.

The serum tryptophan to large neutral amino acids ratio (Try/LNAA) is considered a reliable marker of tryptophan availability for brain serotonin synthesis. A dysfunction of brain serotonergic activity has been postulated to exist in autistic disorder and supported by recent studies. On this basis, we determined the serum amino acids levels in 40 children with idiopathic infantile autism as well as in 46 control children. A significantly lower serum Try/LNAA ratio was observed in the autistic subjects compared to the normal controls. In 14 autistic children (35%) this ratio was 2 SD below the mean value obtained in the control group. These results suggest that a low brain tryptophan availability due to a low serum Try/LNAA ratio could be one of the possible mechanisms involved in the alteration of serotonergic function in autism.

Adolescent↗

PubMed1994

Identification of a protein encoded by a mouse simple repeated sequence.

In order to study the possibility that a mouse repeated 'simple sequence', containing an ORF, could encode a protein, we inserted a fragment of a cDNA clone into the expression vector pEX31C. The fragment containing the short sequence 'CAGAGAGG' was expressed as MS2 polymerase fusion protein in Escherichia coli. This fusion protein (H5fp) was injected subcutaneously into rabbit and the corresponding polyclonal antibodies generated. Western blot analysis of proteins extracted from different mouse tissues established that anti H5fp antibodies recognized, in vivo, an antigen of 28 KDa. Immunolocalization with anti H5fp antibodies showed the presence of the related antigen in the cytoplasm of the examined sections. An hypothetical secondary structure for the protein was predicted by the Chou and Fasman method.

Amino Acid Sequence↗

PubMed1993

Neuropsychological abnormalities in AIDS and asymptomatic HIV seropositive patients.

Neuropsychological and immunological parameters were studied in 36 AIDS patients with early disease and without clinical, laboratory, and neuroradiological signs of CNS impairment, and also in 33 asymptomatic HIV seropositive subjects. Many AIDS patients performed abnormally on timed psychomotor tasks, tasks involving sequencing and "set-shifting", and memory tasks stressing attention, learning, active retrieval, and monitoring of information. Asymptomatic HIV seropositive subjects as a group did not perform significantly worse than controls. However, on the basis of a cut off number of pathological performances on neuropsychological tasks, 52.8% of AIDS and 30.3% of asymptomatic HIV seropositive subjects had cognitive impairment, compared with 3.9% of HIV seronegative controls. Low values of CD4+ cells and of CD4+/CD8+ ratio and high titres of P-24 antigen in the blood prevailed among subjects with cognitive impairment, especially in the asymptomatic HIV seropositive group.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Neuropsychological markers of dementia on visual-spatial tasks: a comparison between Alzheimer's type and vascular forms of dementia.

The incidence of the "closing-in" phenomenon and of the tendency to give "primitive answers" on the Raven's Colored Matrices was studied in 50 normal subjects and in two groups of Alzheimer's type (n = 41) and of vascular (n = 35) dementia patients, carefully matched as for the overall severity of dementia and the degree of visual-spatial impairment. The aims of this research were to determine if these patterns of behavior can be considered as neuropsychological markers of dementia and if their incidence is similar in the two dementia groups. Results show that both the closing-in phenomenon and the tendency to give globalistic and odd responses on the Raven's Colored Matrices are good markers of dementia and that, in particular, they point to a degenerative, rather than to a vascular form of dementia. From the clinical point of view, these data suggest that a qualitative analysis of the patient's behavior can increase the diagnostic efficacy of neuropsychological tests and that neuropsychological markers of dementia point more to Alzheimer's disease (considered as the most prototypic form of dementia) than to a vascular form of dementia even when the two groups of patients are well balanced in terms of visual-spatial impairment and the overall severity of dementia.

Aged↗

PubMed1992

A mouse repeat sequence conserved in eukaryotic genomes.

To study the biological role of simple repetitive DNA sequences, we analysed a clone isolated from a mouse macrophage cDNA library called T2. This clone contains two simple repetitive sequences: a new sequence, 'CAGAGAGG', and a sequence previously described, 'GATA'. By sequencing analysis, an open reading frame, coding for 225 amino acids, is detected in the T2 clone. The new simple sequence is present thousands of time in the mouse genome, associated or not with the sequence 'GATA'. The sequence 'CAGAGAGG' is transcribed in messenger RNAs. Northern blots of RNAs extracted from adult tissues and from differentiated or non differentiated cell lines show a large number of transcripts that quantitatively decrease when in vitro differentiation occurs. Moreover, Southern blots of DNA extracted from different organisms, hybridize with a fragment containing only the 'CAGAGAGG' sequence, demonstrating that this sequence is represented in the genome of phylogenetically distant eukaryotes, and is highly conserved during eukaryotic evolution.

Amino Acid Sequence↗

PubMed1986

Mechanisms of unilateral spatial neglect in relation to laterality of cerebral lesions.

An Overlapping Figures test, considered as appropriate to study focusing of attention on small but complex stimuli falling in the central parts of visual field and a Searching for Animals test, designed to study the exploration of large parts of extrapersonal space, were administered to 38 controls, and 90 right and 82 left brain-damaged patients. The investigation was designed to test the hypothesis that the extent of space to be explored may have a different influence on unilateral spatial neglect of right and left brain-damaged patients. Both right and left brain-damaged patients showed an asymmetric exploration of space on the Searching for Animals test, making more omissions on the side contralateral to the damaged hemisphere than on the ipsilateral one. On the Overlapping Figures test, however, only right brain-damaged patients showed a clear tendency to omit figures lying on the left side of the composite pattern. This finding suggests that inability to extract visual information from one side of the stimuli during single eye fixations may be the most characteristic feature of unilateral spatial neglect resulting from right hemisphere lesions.

Attention↗