PubMed Health⌕ Search

Biomedical subjects

F De Luca

Publications and source records attributed to F De Luca.

At least 19 recordsLinked to original sources
PubMed1992

Alteration of the passive electrical properties of lymphocyte membranes induced by GM1 and GM3 glycolipids.

The electrical conductivity of normal human lymphocyte suspensions has been measured in the frequency range from 10 kHz to 100 MHz, where a well-pronounced conductivity dispersion occurs, caused by the surface polarization at the interface between the cell membrane and the extracellular solution. We have investigated the alteration of the passive electrical properties of the cytoplasmatic cell membrane induced by two different gangliosides (GM1 and GM3) inserted, at various concentrations, into the outer leaflet of membrane double layer. The alterations observed in the dielectric parameters (the membrane conductivity and the membrane permittivity) derived on the basis of a 'double-shell' model, result in an overall increase of the ion permeation across the membrane and an enhanced polarizability of its hydrophilic region for both gangliosides investigated. The relevance of these alterations is discussed.

Cell Membrane↗
PubMed1992

[Acute intestinal ischemia. Our experience].

Acute intestinal ischemia is a pathology which is relatively often encountered in elderly patients where the concomitance of other diseases make its prognosis more severe, especially since diagnosis is usually late. Laboratory tests and imaging techniques are not of great value to diagnosis since they do not provide pathognomonic data, but together with a careful anamnesis they contribute a series of findings which, taken as a whole, lead to the diagnosis of intestinal ischemia. The sole therapy is surgery--when still possible and the best results are obtained when surgery is performed at an early stage. The authors report a series of 12 cases of acute intestinal ischemia and underline the difficulty of diagnosing this subtle pathology and the advantages of aggressive surgical techniques.

Abdomen↗
PubMed1992

Spin-lattice relaxation in murine tumors after in vivo treatment with interferon alpha/beta or tumor necrosis factor alpha.

1H NMR spin-lattice relaxation times (T1) were measured in vitro and in vivo in Friend leukemia cell tumors during subcutaneous tumor growth in syngeneic mice and after in vivo administration of either purified murine interferon alpha/beta (IFN) or recombinant tumor necrosis factor alpha (TNF). Untreated tumors exhibited monoexponential T1 relaxation independently of tumor age at least until Day 16 after implantation. Histological examinations showed that under these conditions tumors were highly homogeneous and substantially free of necrotic areas. Peritumoral administrations of either IFN or TNF did not significantly alter the tumor relaxation properties at early stages of inhibition of tumor growth. The longitudinal relaxation decay became instead clearly biexponential at later stages (more than 7 days of IFN treatment or 2 days after TNF administration). While the T1 relaxation behavior could be unequivocally correlated with the presence of necrotic areas in these tumors, it could not be considered as an early marker of the altered growth capability, induced by administration of either IFN or TNF.

Animals↗
PubMed1992

Diagnostic value of growth hormone-releasing hormone test in children and adolescents with idiopathic growth hormone deficiency.

Average growth hormone (GH) peaks following an i.v. growth hormone releasing hormone (GHRH) 1-29 stimulation test were significantly lower in 48 children and adolescents with GH deficiency (GHD) than in 20 age-matched controls (15.2 + 12.7 vs 37.5 + 28.1 ng/ml, 2 P less than 0.001). Twelve patients exhibited a low GH peak (less than 5 ng/ml), 27 demonstrated a normal response (greater than 10 ng/ml) and 9 showed an intermediate rise in plasma GH (5-10 ng/ml). Six of the 12 patients with low GH response to the first GHRH stimulation failed to respond to two other tests immediately before and after a 1 week priming with s.c. GHRH. These subjects with subnormal GH increase at repeat testing had total GHD (TGHD) and multiple pituitary hormone deficiency (MPHD) and had suffered from perinatal distress. On the contrary, 26 of 27 patients with normal GH response to the first test had isolated GHD and only a minority (8/27) had signs of perinatal distress. It is concluded that perinatal injuries primarily damage pituitary structures and that a pituitary defect more probably underlies more severe forms (TGHD and MPHD) of GHD.

Adolescent↗
PubMed1992

Lee-Goldburg solid-state imaging.

A new approach to solid-state imaging (SSI) is presented. The method relies on narrowing the resonance line using the Lee-Goldburg sequence. The technique is easy to implement in practice and may find widespread applications in materials science.

Magnetic Resonance Spectroscopy↗
PubMed1992

Partial cerebral ischemia assessed by "in vivo" 31P NMR spectroscopy in rats.

31P NMR spectroscopy was used to assess the cerebral ischemia status in rats by measuring the relative levels of phosphate metabolites. Partial cerebral ischemia was induced in 49 rats by reversible occlusion of the carotid arteries. Rats were intubated and mechanically ventilated on a hypoxic gas mixture. Physiological parameters such as temperature and arterial pressure were strictly controlled during the experiments. 31P spectra were acquired at 7 T during basal observation, for 15-20 min after the induction of ischemia, and for 1 hr after reperfusion. Depletion and increase in PCr and Pi levels, respectively, were already observable in the collected spectra within few minutes after the onset of ischemia. No appreciable changes were found in the ATP levels.

Animals↗
PubMed1992

Immiscible fluids permeability by T1 imaging.

Soil pollution by hydrocarbon compounds is an important part of the more general pollution problem. Some analogies with research problems encountered in studies of oil reservoirs in rocks suggested to us the opportunity to study the pollution dynamics by imaging the spatial distribution of the pollutant in a wet soil model by an NMR imaging technique. Some preliminary results using T1-weighted imaging are reported here.

Magnetic Resonance Spectroscopy↗
PubMed1992

The effect of feeding on plasma immunoreactive ACTH and beta-endorphin levels in newborn infant.

In order to clarify whether an interaction between endogenous opioids and feeding occurs at birth, we studied Beta-endorphin (beta-EP) and ACTH plasma levels in response to a feed of 10% glucose, or formula, in 120 healthy full-term infants. Neither postprandial beta-EP nor ACTH increases were found at the 24th hour or on the fourth day of life. beta-EP physiology in newborn infants seems to be different from adults.

Adrenocorticotropic Hormone↗
PubMed1992

Comparison between serum CA 125 and CA 19-9 assays and tissular OC 125 and 1116NS 19-9 reactivity in malignant and benign ovarian tumors.

This preliminary study included 25 patients with primary epithelial ovarian cancer (EOC) (18 serous, 3 serous-mucinous, 1 endometrioid, 2 undifferentiated carcinomas and 1 malignant Brenner carcinoma); 2 patients with borderline ovarian tumors and 20 patients with benign ovarian tumors (9 benign cystic teratomas, 6 serous cystoadenomas and 5 mucinous cystoadenomas). Blood samples for the measurement of CA 125 and CA 19-9 were drawn from all patients before surgery. Serum CA 125 (Reference Value-RV = 65 U/ml) and CA 19-9 (RV = 40 U/ml) were measured with IRMAs using the monoclonal antibodies (MoAbs) OC 125 and 1116NS 19-9. The same antigens were detected on paraffin-embedded tissue sections by immunocytochemistry with the avidin-biotin complex method employing the same MoAbs used for serum IRMAs. Among the 25 patients with EOC serum CA 125 levels were elevated in 20: tissular OC 125 reactivity was observed in 15 (75%) of them. Of the 5 EOC patients with normal CA 125 levels, 4 showed OC 125 reactivity. Only 2 of the 25 EOC patients had elevated serum CA 19-9 levels: one of them had tissular 1116 NS 19-9 reactivity. Among the 23 patients with normal serum CA 19-9 levels only 5 had immunocytochemical reactivity for this antigen. The 2 patients with borderline ovarian tumors had negative serum CA 125 and CA 19-9 assay: tissular OC 125 reactivity was observed in both patients, while 1116 NS 19-9 reactivity was detected in only one.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1992

[Left ventricular false tendon: the most frequent cause of "innocent" murmur in childhood?].

BACKGROUND: The left ventricular false tendon (FT) is an anomalous fibrous or fibromuscular band stretching across the left ventricle. The false tendons extend from the septum to the left ventricular free wall or, more rarely, from the septum to a papillary muscle. The association between FT and innocent cardiac murmur has been pointed out. The aim of the present study was to assess the incidence of FTs in children with a murmur classified as innocent. METHODS: Two groups of subjects were selected. Group A consisted of 253 children with: 1) systolic ejection murmur; 2) normal electrocardiogram and 3) absence of clinical data suggesting cardiac disease. Group B consisted of 240 children clinically free of cardiac disease, and without any cardiac murmur. A FT was diagnosed by means of 2D echocardiogram whenever a linear band stretching across the left ventricular chamber was evident in at least two sections. RESULTS: One hundred and sixty-one children of group A (63.6%) reflected a left ventricular FT; only in 3 patients out of 161 the FT was associated with a small ventricular septal defect, whereas in 158 children the FT was the only abnormal finding. A normal echocardiogram was observed in 71 children (28.1%) of group A; whereas in 21 patients (8.3%) a congenital heart disease was diagnosed. In group B, only 33 subjects (13.8%) had a FT. The different incidence of FT in the two groups (63.6% versus 13.8%) was statistically significant (p less than 0.01). CONCLUSIONS: The study shows that about two thirds of children with innocent heart murmur reflect a left ventricular FT. Furthermore, FT is far more common in subjects with innocent cardiac murmur than in normal subjects. The relationship between FT and murmur thus appears very likely, although not definitely proven.

Adolescent↗
PubMed1991

Mitochondrial DNA in the sea urchin Arbacia lixula: nucleotide sequence differences between two polymorphic molecules indicate asymmetry of mutations.

Two polymorphic forms of mitochondrial DNA (mtDNA) extracted from Arbacia lixula eggs were cloned and the nucleotide sequences of specific regions determined. A comparison of the sequences of the sense strand of the two molecules demonstrates that all the differences are transitions and only of the A----G type. A change such as G----A (or A----G) on the sense mtDNA strand results from either a direct G----A (or A----G) mutation on that strand or a C----T (or T----C) on the complementary strand. None of the C----T (or T----C) changes were detected on the sense strand, which implies that the A----G mutation bias on the sense strand is not reversed for the other strand. Our observation indicates the existence of mechanisms acting asymmetrically on the two mtDNA strands, possibly during mtDNA replication.

Amino Acid Sequence↗
PubMed1991

Insulin secretion, glycosylated haemoglobin and islet cell antibodies in cystic fibrosis children and adolescents with different degrees of glucose tolerance.

In comparison with 12 weight-matched controls, 39 children and adolescents with cystic fibrosis (CF) showed higher fasting glycaemic levels and both delayed and enhanced blood glucose responses to OGTT. Glycaemic response was normal in 30/39 patients (76.9%), impaired in other 7 cases (18%) and diabetic in the remnant two (5.1%). Fasting insulin levels and total insulin output during OGTT did not differ in patients and controls, but insulin peak in CF group was delayed and sustained. In the whole CF series mean HbA1c was higher than in controls but no difference was found between patients with normal and those with impaired glucose tolerance. Islet cell antibodies were absent in the entire CF group. In conclusion, our results confirm the raised prevalence in CF of glucose tolerance abnormalities, which do not seem to depend on auto-immune factor involvement. Delayed insulin response to OGTT can be considered a very early expression of beta cell impairment in the course of CF. In our experience HbA1c assay did not constitute a sensitive and specific screening test for detection of the C patients with glucose intolerance.

Adolescent↗
PubMed1991

Atrial natriuretic peptide and renin-aldosterone relationship in healthy newborn infants.

Plasma atrial natriuretic peptide (ANP) and aldosterone concentrations, and plasma renin activity (PRA) were measured by radioimmunoassay concurrently in 20 healthy full term infants, in cord blood, at 24 hours after birth and on the 4th day of life. ANP and aldosterone increased significantly at 24 hours and was persistently elevated on the 4th day of life. PRA remained unchanged during the first four days of life. In cord blood, ANP concentrations were correlated with aldosterone concentrations (r = 0.49, p less than 0.05) and hematocrit (r = 0.58, p less than 0.02). At the 24 hours of life, plasma ANP concentrations were correlated with weight loss observed on the 4th day of life (r = -0.70, p less than 0.005), while the percentage changes in plasma aldosterone concentrations were correlated with percentage changes in systolic blood pressure (BP) (r = 0.49, p less than 0.05). These findings suggest that during the early newborn period ANP and aldosterone act as an integrated system which has a role in regulation blood pressure and intravascular volume homeostasis.

Age Factors↗
PubMed1991

Long-lasting catch-up growth under bio-methionyl growth hormone treatment in an infant with isolated growth hormone deficiency type 1A.

This case report concerns a 7-month-old infant with severe height retardation (-5.0 SD), typical growth hormone (GH)-deficient phenotype, and undetectable GH serum levels in response to three pharmacological stimuli. Diagnosis of isolated GH deficiency type 1A was confirmed by restriction endonuclease analysis of genomic DNA which pointed out GH-N gene deletion. The introduction of bio-methionyl-GH therapy in this patient was followed by a transient and clinically irrelevant appearance of low binding capacity GH antibodies as well as by a long-lasting catch-up growth (42.2 cm) which is continuing 44 months after beginning of treatment. This atypical pattern confirms that immune and growth response to exogenous GH in isolated GH deficiency 1A may be very heterogeneous.

Autoradiography↗
PubMed1991

[The clinical and histopathological findings in 110 cases of leukoplakia of the oral cavity].

The authors value the distribution of some parameters such as age, sex, life habits, kind of clinical diagnosis and its relation to histological diagnosis in a population of 110 patients heterogeneous for rank and provenance. After describing the kind of casualty department aid, they explain the meaning of the word leukoplakia and underline the difficulties of clinical diagnosis: the macroscopic appearance of the white patch (according to WHO definition) is often comparable to other oral diseases either classified as precancerous lesions or not.

Diagnosis, Differential↗
PubMed1990

Direct evidence that restriction endonucleases may under estimate the degree of divergence between molecules.

We studied two polymorphic forms of mtDNA extracted from A. lixula eggs. In order to compare and to quantitate the variability, we sequenced specific regions of the two molecules. In this way, we obtained a precise measurement of the variability within two haplotypes. We also obtained a direct demonstration that some differences in nucleotide sequence can escape detection when restriction endonuclease analysis is used. Our results underline the unreliability of the use of restriction mapping to estimate divergence between relatively short and closely related DNA sequences.

Animals↗