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Biomedical subjects

P Benedetti

Publications and source records attributed to P Benedetti.

At least 55 records · Page 3Linked to original sources
PubMed1990

Template supercoiling by a chimera of yeast GAL4 protein and phage T7 RNA polymerase.

Fusion of the DNA-binding domain of yeast GAL4 protein to the amino terminus of bacteriophage T7 RNA polymerase yields a chimera that retains the characteristics of its components. The presence of the GAL4 peptide allows the chimeric enzyme to anchor itself on the DNA template, and this anchoring in turn drives the formation of a supercoiled DNA loop, in linear or circular templates, when RNA synthesis at the polymerase site forces a translocation of the DNA relative to the site. Nonspecific interaction between the chimeric enzyme and DNA appears to be sufficient to effect supercoiling during transcription. Transcription by the chimeric polymerase is strictly dependent on the presence of a T7 promoter; thus it provides a tool in vitro and in vivo for specifically supercoiling DNA segments containing T7 promoter sequences.

Amino Acid Sequence↗
PubMed1989

Expression of human DNA topoisomerase I in yeast cells lacking yeast DNA topoisomerase I: restoration of sensitivity of the cells to the antitumor drug camptothecin.

Yeast Saccharomyces cerevisiae strains that are permeable to the antitumor alkaloid camptothecin are killed by the drug if they express DNA topoisomerase I, the cellular target of the drug (J. Nitiss and J.C. Wang, Proc. Natl. Acad. Sci. USA, 85: 7501-7505, 1988). We show that in a yeast strain permeable to camptothecin but lacking DNA topoisomerase I, sensitivity to the drug was restored upon expression of human DNA topoisomerase I from a plasmid-borne human complementary DNA clone. When the human enzyme was expressed from a galactose-inducible, glucose-repressible yeast promoter, PGAL1, sensitivity to camptothecin was observed in the presence of galactose but not in the presence of glucose. Expression of human DNA topoisomerase I in Escherichia coli was also demonstrated by the complementation of a conditional lethal E. coli DNA topoisomerase I mutant. These systems can be used in the study of human DNA topoisomerase I-camptothecin interactions and in the screening of additional therapeutics targeting the enzyme.

Base Sequence↗
PubMed1989

A national voice for information about HIV infections: the Italian state AIDS hot-line.

Because of the variety of problems connected with the AIDS epidemic, there is an urgent need for qualified information and counselling. In June 1987, The Italian Ministry of Health established a hot-line, acting within the National AIDS Operational Centre. Through the analysis of more than 39,000 calls received during the first year of activity, a clear outline has been obtained of the emotional impact of the disease on Italian public opinion, and of the problems raised. 67% of callers belong to 20-39 age group; the male/female ratio is 2:1. Interesting correlations have been found between the content of the questions and the sex, age, and type of caller. The vast majority of questions concerning basic concepts and notions about HIV infections are asked by no-risk-related subjects. During the first year, the percentage of questions asked by subjects actually at risk increased, and the questions themselves have become more specific.

Adult↗
PubMed1989

[Continuous localized EEG discharges during sleep in children].

Continuous generalized spike-and-wave complexes occurring during slow-sleep were first observed in some children by Patry et al. (1971). A general review of the reported cases was made by Tassinari et al. (1984). We have observed a new clinical-EEGraphic picture. Spikes and spike-and-wave complexes localized to one hemisphere were recorded during at least 85% non-REM sleep both in 3 quadriplegic and in 3 hemiplegic mentally retarded children, aged from 2 years and 10 months to 11 years (mean age: 5 years and 2 months). Cyclic organization of sleep was almost normal. Wake EEG showed an epileptic focus. Brain CT showed midline defect and brain atrophy in quadriplegic patients, and a wide temporal-parietal porencephalic cyst in hemiplegic patients. This EEGraphic pattern was associated with a more pronounced mental impairment: neuropsychological improvement was observed in 2 cases, when continuous sleep discharges disappeared. As aforesaid, this picture seems to be related either to hemispheric or to midline brain defects. In our cases, sleep phase organization could be examined, while continuous generalized discharges occurring during sleep do not allow such a study.

Child↗
PubMed1989

The Italian AIDS 'hot-line': providing information to the people.

The Italian AIDS hot-line has recently completed its first two operational years. Established as an emergency service, it was initially overloaded with calls, under the emotional impact of a new disease. As the average number of calls settled to around a hundred per day, a wider approach aimed at the concerns raised by callers has been possible. A particular effort has been made to handle psychological and social aspects of HIV infections. A large proportion of the questions analyzed (62,500) deal with doubts about transmission (30%), reliability of diagnostic tests (15%), and handling individual situations. Some categories of callers, such as drug users, parents or relatives of HIV-infected people, and seropositives often require experienced telephone counselling. HIV-positive callers follow the proportional distribution of AIDS cases in Italy: intravenous drug users forming the majority, followed by homosexuals and finally heterosexual subjects (reaching 10%, a value in accordance with trend projections). The demand for advice has increased over time, together with an evident refinement of question content.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Functional and surface phenotype study of lymphocyte subsets in peripheral blood and lymph nodes of breast cancer patients.

In an attempt to identify lymphocyte subsets possibly involved in the response to malignant cells, we have studied the lymphocyte surface phenotype by using a panel of monoclonal antibodies on both peripheral blood lymphocytes (PBL) and histologically proven metastatic and nonmetastatic (i.e., "hyperplastic") axillary lymph node lymphocytes (LNL) from eight breast cancer patients. Furthermore, we carried out a functional study by evaluating the response to polyclonal mitogens of the PBL and of the LNL of the same patients. A group of 30 healthy subjects, age and sex matched, were selected as controls for PBL. Six of them, who underwent surgery for nonneoplastic conditions, were selected as controls for LNL. The responsiveness of breast cancer patients' PBL to polyclonal mitogens phytohemagglutinin (PHA) and concanavalin A (Con A) was significantly lower as compared with the control response. The responsiveness of breast cancer patients' metastatic LNL was not different from control LNL for PHA, and it was lower than control LNL for Con A, while the responsiveness of the same metastatic LNL was higher than that of nonmetastatic (i.e., hyperplastic) LNL of patients. Furthermore, the response of hyperplastic LNL was always lower than that of control LNL. The responsiveness of patients' PBL was always lower than that of metastatic LNL, while the responsiveness of patients' PBL vs. hyperplastic LNL was at variance. Regarding the surface phenotype of PBL, there was no difference between those of breast cancer patients and controls concerning the T-cells subsets, while the Leu 7, CD 21 and DR antigens were significantly higher among the breast cancer patients. No significant differences were found between patient metastatic and hyperplastic LNL or between control LNL and patient metastatic or hyperplastic LNL, respectively; only the CD 4 antigen was higher in metastatic than in hyperplastic LNL. A comparison of this surface phenotype between PBL and either metastatic or hyperplastic LNL of breast cancer patients showed values almost constantly significantly higher for PBL vs. either metastatic or hyperplastic LNL, respectively. The results of our study suggest that there is no change in the local-regional immunocompetent cell subsets that may be related to metastasis of breast cancer to regional nodes and to the progression of disease and that circulating T cells in breast cancer include cells expressing activation markers but not showing significant changes in the proportion of entire subpopulations.

Adult↗
PubMed1988

Prognosis of partial epilepsy.

The prognosis of partial epilepsy in childhood (excluding cases of benign partial epilepsy) was studied; the average follow up period was 7.4 years. Improvement rate of seizure status was 82.3%. We studied favourable prognostic factors and found that those most often associated with seizure improvement were familial convulsions and idiopathic forms, no generalised seizures before partial onset, low frequency of seizures after 12 months of treatment, short duration of epilepsy, and no background activity abnormalities on electroencephalography. We also observed such factors as mental retardation, neurological abnormalities, and behaviour and cognitive disorders. Factors that determined the prognosis for social adjustment were similar to those for seizure improvement. We discuss the favourable prognosis of partial seizures in childhood and the predictive factors.

Adolescent↗
PubMed1987

Comparative mutational analysis of wild-type and stretched tRNA3(Leu) gene promoters.

We demonstrate that, when the yeast tRNA(3Leu) gene is stretched so that the distance between the two portions of the intragenic promoter is increased to 365 base pairs, the A and B blocks remain functional. Mutations in the A block, which show a weak phenotype when inserted in the wild type, exert a dramatic effect when inserted into the stretched gene. Experiments with extensively purified transcription factor tau indicate that the tau B-B block interaction is not influenced by A-B distance; only the ability of tau A to interact with A block sequences is affected, possibly because of the additional free-energy cost of forming a large loop of the intervening DNA.

Base Sequence↗
PubMed1986

Increased chromosomal breakage in epileptic children after long-term treatment.

To investigate the mutagenic effects of antiepileptic drugs (AED), 39 epileptic children treated by long-term monotherapy (10 cases with Pb, 11 with Cbz, 9 with Vpa, 8 with Pht) have been studied. The long-term administration was monitored by measurement of AED serum concentrations by gaschromatography. Metaphase chromosome observations were performed using short time culture of peripheral blood lymphocytes and 100 mitoses from each proband were analyzed. A significant increase of CA in the group of patients with Pb (0.23), Cbz (0.19), Vpa (0.25), Pht (0.18) as compared with those of nine epileptic children without treatment (0.08) has been found. Because unrepaired damage of DNA may act as a possible carcinogenic potential, the shortest possible duration of AED treatment is recommended.

Adolescent↗
PubMed1986

Upper limb movements in the emergence of object cognition.

Previous studies showed that 40% of fullterm newborns with "anterior plane hypotonia" (APH) neuromotor anomaly present retarded development of object cognition. To understand the possible motor dynamics of this retardation, we studied the principal upper limb movements in a group of normal newborns and in one of APH newborns, with and without stimulus. The total quantity of movement proved to be similar in the two groups but there were differences in the frequencies of the various types of movement, to the detriment in the APH subjects of the movements considered most relevant to object relations. These data underline the importance of the qualitative integrity of newborn movement to the emergence of object cognition.

Arm↗
PubMed1983

Purification and characterization of Xenopus laevis topoisomerase II.

We have purified to apparent homogeneity a type II DNA topoisomerase from Xenopus laevis oocyte nuclei (germinal vesicles, or GV). The most pure preparations contain a single polypeptide of 175,000 daltons as determined by SDS-gel electrophoresis. The enzyme changes the linking number of DNA circles in steps of two and reversibly knots or catenates DNA rings. No gyrase activity is detectable and ATP is required.

Animals↗
PubMed1980

In vitro catenation and decatenation of DNA and a novel eucaryotic ATP-dependent topoisomerase.

Extracts from X. laevis germinal vesicles interlock duplex DNA circles to form catenanes. The catenation activity requires Mg++ and ATP. Negatively supercoiled or relaxed DNA can be used as substrates for the catenation reaction. Homology between donor and acceptor DNA is not required, since catenanes are formed between DNA molecules with unrelated sequences. In the course of the isolation of the activity responsible for the catenation reaction, we discovered a new ATP-dependent topoisomerase. The fractions containing the novel topoisomerase catenate and decatenate DNA, the ionic strength dictating which of the two opposing reactions will occur.

Adenosine Triphosphate↗
PubMed1979

Separation of RNA transcription and processing activities from X. laevis germinal vesicles.

A procedure suitable for en masse preparation of germinal vesicles (GV) from X.laevis oocytes (Scalenghe et al., 1978) has been adapted for studies of transcription. Extracts from GV contain activities for transcription of tRNA genes and for processing the transcription product. The two activities have been separated by column chromatography. One fraction allows synthesis of tRNA precursor molecules in the presence of X.laevis RNA polymerase III. Another fraction contains the activity that cuts and splices those precursors which contain an intervening sequence. Transcription occurs faithfully on linear DNA fragments.

Animals↗
PubMedDate not supplied

Six cases of travel-associated Legionnaires' disease in Ischia involving four countries.

The detection of travel-associated legionellosis can be extremely difficult; hence, an extensive case investigation is recommended in pneumonia-striken travellers and tourists, who are particularly at risk of acquiring the disease. On the Island of Ischia (Isola d'Ischia, Naples, Italy) a total of six cases of Legionnaires' disease occurred from 1986 to 1990. All patients (one man and two women from Germany, one Austrian woman, one Swiss man, and one Italian woman) had taken thermal baths and stayed in local hotels; they all experienced severe pneumonia, and three of them died. These cases were associated with hotels, and the hot-water supply was presumed to have transmitted the infection. Remedial procedures were applied to the hot-water plumbing of the hotels according to the WHO recommendations and were proved to be effective. The occurrences described in this paper stress the importance of rapid and accurate reporting of diagnosed cases to the country where the infection was probably acquired, in order to ensure early detection of endemic foci and emerging clusters of legionellosis.

Aged↗