Search PubMed⌕ Search

Biomedical subjects

A Torricelli

Publications and source records attributed to A Torricelli.

17 recordsLinked to original sources
PubMed1997

From flow cytometric BrdUrd data to cell population growth and doubling time.

We describe a direct way to use flow cytometric data for measuring the growth curve of a cell population. The starting point is analysis of the intrinsic informative content of the time course, after bromodeoxyuridine (BrdUrd) labeling, of the percentages of cells detected within four windows of biparametric BrdUrd-DNA histograms. We did not introduce a particular cell cycle model or use the hypothesis of exponential growth. We obtained a simple formal proof of the existence of four independent formulae connecting the flow cytometric data and the relative growth curve of the cell population. The formulae were then challenged in a number of simulated kinetic scenarios, moving away from their expected limits of validity. The results suggest additional uses of the formulae and a way of estimating cell-cycle-phase durations. Considering exponential growth in the presence of cell loss, the formulae were used to estimate the potential doubling time from a single flow cytometric measure vs. other procedures that additionally require an estimate of the duration of the phase S. The theoretical precision of the procedures may differ depending on how cell loss occurs.

Antimetabolites↗
PubMed1997

A solid tissue phantom for photon migration studies.

A solid tissue phantom made of agar, Intralipid and black ink is described and characterized. The preparation procedure is fast and easily implemented with standard laboratory equipment. An instrumentation for time-resolved transmittance measurements was used to determine the optical properties of the phantom. The absorption and the reduced scattering coefficients are linear with the ink and Intralipid concentrations, respectively. A systematic decrease of the reduced scattering coefficient dependent on the agar content is observed, but can easily be managed. The phantom is highly homogeneous and shows good repeatability among different preparations. Moreover, agar inclusions can be easily embedded in either solid or liquid matrixes, and no artefacts are caused by the solid-solid or solid-liquid interfaces. This allows one to produce reliable and realistic inhomogeneous phantoms with known optical properties, particularly interesting for studies on optical imaging through turbid media.

Agar↗
PubMed1996

Experimental test of theoretical models for time-resolved reflectance.

Four different expressions, derived from the diffusion theory or the random walk model, were used to fit time-resolved reflectance data for the evaluation of tissue optical properties. The experimental reflectance curves were obtained from phantoms of known optical parameters (absorption and transport scattering coefficients) covering the range of typical values for biological tissues between 600 and 900 nm. The measurements were performed using an instrumentation for time-correlated single-photon counting. The potential of the four methods in the assessment of the absorption and transport scattering coefficients was evaluated in terms of absolute error, linearity error, and dispersion of data. Each method showed different performances depending on the optical properties of the sample and the experimental conditions. We propose some criteria for the optimal choice of the fitting method to be used in different applications.

Biophysical Phenomena↗
PubMed1992

Bioelectric brain maturation in fullterm infants and in healthy and pathological preterm infants at term post-menstrual age.

At the same post-menstrual age (39-41 weeks), EEG maturation assessed according to the Nolte and Haas method (Nolte, R. and Haas, H.G. (1978) Dev. Med. Child Neurol., 20, 167-182) was studied in 16 fullterm infants (FT), 17 healthy preterm infants (HP) and 18 pathological preterm infants (PP) affected by brain lesions (haemorrhage and/or leucomalacia). There were no significant differences in respect to EEG maturational codes, EEG types or bioelectrical age between the FT and HP groups. The preterm infants affected by brain lesions presented higher percentages of younger EEG codes (i.e. 36 weeks) in State 1 and a higher number of fluctuations between one maturation code and another in both State 1 and State 2, with respect to the HP group. Also, although the PP infants with young EEG codes did not present serious background EEG abnormalities, they did reveal minor EEG abnormalities, such as excessive asynchrony of the 'tracé alternant', lack of frontal sharp transients and monomorphic TA 'bouffees' with little activity at 2-6 c/s. However, no relationship between young EEG codes and onset-offset or duration of the states was found: young codes were often randomly distributed in successive State 1-State 2 epochs, regardless of groupings. Bioelectric age appropriate to the post-menstrual age precedes a normal development or only minor handicap at 24 months, while EEG immaturity of more than 2 weeks corresponds to later major handicaps. The prognostic value of EEG immaturity of between 1.1 and 2 weeks is uncertain.

Brain↗
PubMed1990

Intravenous lidocaine in the treatment of convulsions in the neonatal period: monitoring plasma levels.

Thirteen newborn infants (five premature, eight full term) with severe seizures and not responding to phenobarbital and diazepam received a lidocaine (LD) infusion. The schedule was 4 mg/kg/h on the 1st day, 3 mg/kg/h on the 2nd day, 2 mg/kg/h on the 3rd day, and 1 mg/kg/h on the 4th day. The LD plasma levels were measured every 24 h just before decreasing the dose. The control of seizures was achieved in 11 of 13 patients, with plasma LD concentration ranging from 2.8 to 10.5 mg/L. The LD concentration was linearly correlated with the dose in each group. In the premature group, LD clearance was always smaller than in the full-term group. Although no side effects were observed on heart rate and blood pressure, it is suggested that the dose of LD be adjusted to maintain the LD concentrations between 3-6 mg/L.

Diazepam↗
PubMed1986

Visual orientation to the human face in the premature and fullterm newborn.

Visual orientation to the human face was studied by the method of Brazelton in 15 fullterm newborns on the 4th-5th day of life and in 21 premature newborns (gestational age 27-37 weeks) tested weekly up to 40 weeks conceptional age. No evidence of visual orientation was found before 33 weeks. Performances on a par with those of fullterm newborns were not attained until 37-38 weeks on average, though in a few cases this was achieved at 35 weeks. The quality of orientation improved gradually from 32-33 weeks to 38 weeks, but with wide inter- and intra-individual variations. Noteworthy were the discontinuity and transient worsening of visual orientation of the extremely premature subjects (gestational age less than or equal to 31 weeks) in the weeks following birth. Neurological status at the time of the test, rather than pre-and perinatal risk factors, correlated positively with the quality of the visual responses. No statistically significant differences in orientation were found between premature newborns at term age and fullterm newborns.

Age Factors↗
PubMedDate not supplied

[Follow-up of children born from gestosis mothers].

Seventy children, born from mothers affected from EPH gestosis during pregnancy, were examined. They were two-ten years old, forty females and thirty males, nineteen preterms and fifty-one born at term. Their weight, and head circumference were estimated. Thirty-two children were submitted to terman Merril test and further thirty-eight to Picq Vayer test. The findings were evaluated according to term or preterm birth and to importance of mother's gestosis (EPH1, EPH2, EPH3). The auxological outcomes were satisfactory, particularly after the five-six years of age. Two children were heavily retarded. The others had a normal I.Q., but there was evident failure in immediate memory and in vocabulary's subtest. Moreover fifty % of heavier gestosis children revealed a discordant psycomotor behaviour due to specific failures.

Body Height↗
PubMedDate not supplied

[Up-date on the subject of neonatal convulsions].

New experimental, clinical and therapeutic results in the field of convulsive disorders of the newborn have recently come to light. Experimental studies on animals have shown that, contrary to what was assumed in the past, the immature brain is highly excitable, and during the first weeks of life excitation processes predominate over inhibitory processes. Over the last ten years, benign idiopathic convulsions in newborns, familial convulsions and benign convulsions on the fifth day of life, have been defined. Both types develop and disappear spontaneously during the first week of life and have a favourable prognosis, although they may appear at the start (especially the benign fifth-day convulsions) as status epilepticus. Recently, two types of convulsive status epilepticus in newborns have been identified: a severe idiopathic status epilepticus and focal status epilepticus. The myoclonic syndromes which occur during quiet sleep and which are not accompanied by EEG discharges should be distinguished from convulsions and do not require anti-convulsive therapy. The various EEG monitoring techniques have shown an unexpectedly high number of convulsions, especially in the form of sub-clinical convulsions and/or atypical convulsive seizures. The atypical seizures distinctly predominate in status epilepticus. The clinical evidence of the seizures in reduced by administration of anti-convulsants, which seem to block typical seizures and, viceversa, to be less active for atypical seizures and EEG seizures. In the therapeutic field, the use of phenobarbital and/or phenytoin at a high initial dosage (20 mg/kg) has been well affirmed. Drugs such as lidocaine and thiopental are currently being experimented and have given encouraging results in severe status epilepticus.

Animals↗
PubMedDate not supplied

[Traumatic extradural hematoma in a newborn: a case report].

The authors report the case of a twenty-six-day-old patient presenting a traumatic extradural haematoma. The main clinical aspects of this feature are illustrated and the approach to diagnosis and management is discussed.

Accidental Falls↗