Technetium-99m dimercaptosuccinic acid scintigraphy and pyelonephritic scarring in newborn children.
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Acute Disease↗
Biomedical subjects
L Silvestro
Publications and source records attributed to L Silvestro.
High incidence of adverse reactions to egg challenge on first known exposure in young atopic dermatitis children: predictive value of skin prick test and radioallergosorbent test to egg proteins.
BACKGROUND: Egg skin prick test (SPT) and/or radioallergosorbent test (RAST) positivity has been described in infants and children with a food allergy, or in infants at high risk of atopy who have never eaten eggs. Clinical reactions are also observed when some of these children or infants eat eggs for the first time. OBJECTIVE AND METHOD: A prospective study was made of 107 atopic dermatitis (AD) children (66 boys, 41 girls) aged 1-19 months (median 5 months) who had never ingested egg, to compare the outcome of a first oral egg challenge and the results of albumen and yolk SPTs and RASTs. RESULTS: The egg challenge (conducted at age 12-24 months: mean 16 months, median 15 months) was positive in 72/107 children (67.3%). The reactions were immediate or early (first 6 h) in 56/72 (77.8%). The most severe (all within the first 6 h) were one case of anaphylactic shock (1.4%), three cases of laryngeal oedema (4.1%) and one serious attack of asthma (1.4%). The skin weal diameter at and above which reactions always occurred was 5 mm for both albumen and yolk. They were, however, also observed in the complete absence of a weal. The outcome of the challenge was always positive when the specific IgEs (sIgE) for albumen and yolk were > 99 KU/L and > or = 17.5 KU/L, respectively. Here, too, reactions were noted even when sIgE levels were < 0.35 KU/L. CONCLUSION: AD children who have never eaten eggs may be sensitized and display reactions at the first ingestion. The percentage of reactions in this series was by no means negligible. These findings were observed in children with mild as well as moderate-severe AD when first examined. SPT for albumen and yolk diameter > or = 5 mm, and sIgE for albumen > 99 KU/L and for yolk > or = 17.5 KU/L were 100% specific in predicting the outcome of the challenge. It may thus be concluded that children with AD whose SPT and/or RAST for albumen and/or yolk are equal to or higher than these cut-off values should not be subjected to the oral challenge when consideration is given to the introduction of egg in their diet. Even when these cut-offs are not reached, however, clinical reactions to the challenge cannot be ruled out a priori, and it should be preferably performed in a protected environment, such as a hospital.
Dermatitis, Atopic↗
Leptin levels in breast-fed and formula-fed infants.
AIM: Leptin, a hormone that regulates food intake and energy metabolism, is present in breast milk and thus may be involved in body composition differences between breastfed and formula-fed infants. The aim of this study was to evaluate whether diet and gender affect plasma leptin concentration in breastfed and formula-fed infants during the first months of life. METHODS: Anthropometric and bioelectrical impedance measurements [total body water (TBW) calculated with the Fjeld equation] were made and venous blood plasma samples were analysed for leptin concentration in healthy, exclusively breastfed or formula-fed Italian infants in the first year of life. Infants were subdivided in two ways: three groups (periods) in relation to age, and five groups in relation to weight. RESULTS: The average serum concentration of leptin was 7.35 ng x ml(-1). Serum leptin values were higher in breastfed than in formula-fed infants. Breastfed infants in group I had a statistically higher serum leptin concentration (2,500-3,749 g). There were no significant differences in anthropometric measurements, body mass index or skinfold thickness between breastfed and formula-fed infants. In the periods I and II, breastfed infants had a significantly higher TBW than formula-fed infants. Males had a significantly higher TBW than females in periods I and II. Breastfed infants in group 2 (3,750-4,999 g) had a significantly higher TBW than formula-fed infants. CONCLUSION: The data on TBW, weight and skinfold thickness suggest that the higher leptin concentration observed in breastfed infants in the first months of life may be due not only to adipose tissue production but also to human milk.
Analysis of Variance↗
Dog bites in children less than fourteen years old in Turin.
BACKGROUND: The purpose of this study was to describe the epidemiology of injuries caused by dog bites treated in the emergency department of OIRM from January 1, 1997 to December 31, 2000. METHODS: Data on dog's attacks were obtained from declaration forms filled in the emergency department. RESULTS: 253 children were observed: 145 boys and 118 girls. The mean age was 6.4 years. The peak incidence was in children aged 3 to 8 years old. Fifty-six children (22.31%) required admission to the hospital. Thirty-five were younger than 5 years. Injuries to the face (29.48%), hands (14.55%), legs (9.33%) were more common. The prognosis was 5 (18.97%), 7 (21.74%) and 10 (16.6%) days. Twenty-five children had prognosis over fifteen days (9.88%). Children aged 5 or younger presented most face and hand lesions while children aged 6 to 14 years had most hand, legs and arms injuries. Tetanus and rabies prophylaxis were administered only in 4 and 2 cases respectively, while immunoglobulin anti tetanus were administered in 5 children. The great number of attacks occurred during the summer months, with a peak in June and July. CONCLUSIONS: More attention should be paid to the prevention of dog bites. Pediatricians should advice parents about the risks of interactions with dogs.
Adolescent↗
MAP kinases.
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Mitogen-Activated Protein Kinases↗
Use of an amino-acid formula in the treatment of colicky breastfed infants.
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Amino Acids↗
Influence of thyroid in nervous system growth.
Nervous system growth and differentiation are closely correlated with the presence of iodine and thyroid hormones in initial development stages. In the human species, encephalon maturation during the first quarter of pregnancy is affected according to recent studies by the transplacenta passage of maternal thyroid hormones while it depends on initial iodiothyronin secretion by the foetal gland after the 12th week of pregnancy. Thyroid hormone deficiency during nervous system development causes altered noble nervous cells, such as the pyramidal cortical and Purkinje cells, during glial cell proliferation and differentiation alike. Neurons present cell hypoplasia with reduced axon count, dendritic branching, synaptic spikes and interneuron connections. Oligodendrocytes decrease in number and average myelin content consequently drops. Biochemical studies on hypothyroid rats have demonstrated alterations to neuron intraplasmatic microtubule content and organisation, changed mitochondria number and arrangement and anomalies in T3 nuclear and citoplasmatic receptor maturation. Alterations to microtubules are probably responsible for involvement of the axon-dendrite system, and are the consequence of deficient thyroid hormone action on the mitochondria, the mitochondria enzymes and proteins associated with microtubules. Nuclear and citoplasmatic receptors have been identified and gene clonation studies have shown two families of nuclear receptors that include several sub-groups in their turn. A complex scheme of temporal and spatial expression of these receptors exists, so they probably contribute with one complementary function, although their physiological role differs. The action of thyroid hormones occurs by changing cell protein levels because of their regulation at the transcriptional or post-transcriptional level. Genes submitted to thyroid hormone control are either expressed by oligodendrytes, which are myelin protein coders or glial differentiation mediators, or are nervous cell specific, genes coding neurotropins or proteins involved in synaptic excitation. The use of new PMRS and MRI non-invasive techniques has enabled identification of metabolic and biochemical markers for alterations in the encephalon of untreated hypothyroid children. Even an excess of thyroid hormones during early nervous system development can cause permanent effects. Hyperthyroidism in fact initially induces accelerated maturation process including cell migration and differentiation, extension of dendritic processes and synaptogenesis but a later excess of thyroid hormones causes reduction of the total number of dendritic spikes, due to early interruption of neuron proliferation. Experimental studies and clinical research have clarified not only the correlation between nervous system maturation and thyroid function during early development stages and the certain finding from this research is that both excess and deficient thyroid hormones can cause permanent anatomo-functional alterations to the nervous system.
Animals↗
Membrane-induced folding of cecropin A.
Lipid membranes manifest a diverse array of surface forces that can fold and orient an approaching protein. To better understand these forces and their ability to influence protein function, we have used infrared spectroscopy with isotopic editing to characterize the 37-residue membrane-active antimicrobial polypeptide cecropin A as it approached, adsorbed onto, and finally penetrated various lipid membranes. Intermediate stages in this process were isolated for study by the use of internal reflection and Langmuir trough techniques. Results indicate that this peptide adopts well-ordered secondary structure while superficially adsorbed to a membrane surface. Its conformation is predominantly alpha-helical, although some beta structure is likely to be present. The longitudinal axis of the helical structure, and the transverse axes of any beta structure, are preferentially oriented parallel to the membrane surface. The peptide expands the membrane against pressure when it penetrates the membrane surface, but its structure and orientation do not change. These observations indicate that interactions between the peptide and deeper hydrophobic regions of the membrane provide energy to perform thermodynamic work, but separate and distinct interactions between the peptide and superficial components of the membrane are responsible for peptide folding. These results have broad implications for our understanding of the mechanism of action and the specificity of these antimicrobial peptides.
Amino Acid Sequence↗
Antibacterial and antimembrane activities of cecropin A in Escherichia coli.
The ability of cecropin A to permeabilize and depolarize the membranes of Escherichia coli ML-35p bacteria has been compared to its bactericidal activity in an extension of earlier studies performed on synthetic lipid vesicle membranes (L. Silvestro, K. Gupta, J. H. Weiser, and P. H. Axelsen, Biochemistry 36:11452-11460, 1997). Our results indicate that differences in the concentration dependences of membrane permeabilization and depolarization seen in synthetic vesicles are not manifested in whole bacteria. The concentration dependences of both phenomena roughly correlate with bactericidal activity, suggesting that the bactericidal mechanism of cecropin A is related to membrane permeabilization.
Anti-Bacterial Agents↗
HPLC with on-line mass spectrometry detection application to elucidate erdosteine metabolism: preliminary study.
A newer technique, HPLC with mass spectrometry (MS) detection has been used to evaluate the pharmacokinetics of a new mucoactive compound, erdosteine and its metabolites (N-thioglycolilhomocysteine and homocysteine). To this aim a population of 12 patients of both genders with mean age 52.1+/-6.34 years was enrolled in a trial after protocol approval from Ethics Committee and informed consent obtainment. The patients were treated with erdosteine for 7 days and blood samples were obtained at baseline and on 8th day for analytical purposes. The obtained results are discussed in correlation with those of two previous existing trials on the same product.
Chromatography, High Pressure Liquid↗
The structure of human lipoprotein A-I. Evidence for the "belt" model.
The two main competing models for the structure of discoidal lipoprotein A-I complexes both presume that the protein component is helical and situated around the perimeter of a lipid bilayer disc. However, the more popular "picket fence" model orients the protein helices perpendicular to the surface of the lipid bilayer, while the alternative "belt" model orients them parallel to the bilayer surface. To distinguish between these models, we have investigated the structure of human lipoprotein A-I using a novel form of polarized internal reflection infrared spectroscopy that can characterize the relative orientation of protein and lipid components in the lipoprotein complexes under native conditions. Our results verify lipid bilayer structure in the complexes and point unambiguously to the belt model.
Humans↗
The concentration-dependent membrane activity of cecropin A
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Journal Article↗
Fourier transform infrared linked analysis of conformational changes in annexin V upon membrane binding.
Annexins are ubiquitous cellular proteins of unknown primary function that bind to anionic phospholipid membranes in a calcium-dependent manner. Correlative studies involving X-ray crystallography and electron microscopy suggest that annexins undergo a structural change upon binding to supported lipid monolayer membranes. In this investigation, novel spectroscopic and analytical techniques have been applied to verify and characterize this change. Soluble annexin V was examined with ordinary transmission infrared spectroscopy, while membrane-bound annexin V was examined with both transmission and internal reflection infrared spectroscopy. Spectra were processed by linked analysis, whereby multiple spectra are fit simultaneously with component bands that are constrained to share common fitting parameters. This approach is shown to enhance the sensitivity and accuracy of the bandfitting procedure. Our results are consistent with the general mode of membrane binding inferred from electron microscopy studies, and they provide independent support for the conclusion that annexin V undergoes a conformational change upon binding to lipid monolayer membranes. Most likely, this change involves the formation of new beta structure in which interstrand hydrogen bonds orient parallel to the membrane surface.
Amides↗
Allergy to carob gum in an infant.
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Female↗
IGF-1 and IGFBP in congenital and acquired hypothyroidism after long-term replacement treatment.
BACKGROUND: Thyroid hormones are involved in the regulation of the GH/IGF axis. Hypothyroidism is associated with a reduction in GH pulsatility and in GH-response to stimulatory tests. In hypothyroidism, serum levels of IGF-1 and IGFBP-3 fall and these changes are reversed after short term replacement with L-T4. This study was undertaken to determine the effect of long term replacement therapy with T4 in IGF-1 and IGFBP-3 serum levels. METHODS: The study included 12 patients affected with hypothyroidism and in replacement treatment with T4. They were divided into 3 groups according to age at the beginning of treatment. Group A consisted of 4 pre-pubertal subjects with Congenital Hypothyroidism (CH) diagnosed with neonatal screening, where T4 treatment was started within 15 days of life. Group B consisted of 5 young adults where CH was clinically diagnosed at the median age of 6 months and replacement therapy started at this age. Group C consisted of 3 subjects affected with hypothyroidism secondary to thyroiditis where diagnosis and replacement treatment were delayed at age 11, 12 and 14 respectively. All subjects were matched with a control of the same age, sex, weight and pubertal stage. RESULTS: FT3, FT4 and TSH were in the normal range both in patients and in controls. No correlation was found between FT3 or FT4 and IGF-1 or IGFBP-3 serum levels. IGF-1 serum levels in group A (198 +/- 122 ng/ml) were significantly lower than that in group B (624 +/- 105, p < 0.001) and in group C (649 +/- 98, p = 0.003). IGFBP-3 serum levels in group A (1.98 +/- 0.56 micrograms/ml) were significantly lower than in group B (3.65 +/- 1.10, p = 0.03) and in group C (4.13 +/- 0.49, p = 0.003). The increase in IGF-1 and IGFBP-3 levels was seen also in control groups B and C when compared with control group A. IGF-1 and IGFBP-3 were positively correlated with age both in patients and in controls. A linear correlation was found between IGF-1 and IGFBP-3 which was positive for controls (r = 0.946, p < 0.001) and patient group A and B (r = 0.839, p = 0.005) but tended to be negative for patient group C (r = -0.65, n.s.). CONCLUSIONS: Our data demonstrate that long term replacement therapy in children with hypothyroidism is associated with a physiological increase in IGF-1 and IGFBP-3. The positive correlation between IGF-1 and IGFBP-3 levels in group A and B confirm the efficacy of long term replacement treatment on the IGF-1/BP-3 axis in pre- and post-pubertal patients treated for CH. However, this correlation tended to be negative in patients with hypothyroidism secondary to thyroiditis, suggesting that the cause of thyroid insufficiency and/or the age at the beginning of replacement therapy may have a role in the post-pubertal hormonal status in IGF-1 and IGFBP-3 balance.
Adolescent↗
Folding of beta-sheet membrane proteins: a hydrophobic hexapeptide model.
Beta-sheets, in the form of the beta-barrel folding motif, are found in several constitutive membrane proteins (porins) and in several microbial toxins that assemble on membranes to form oligomeric transmembrane channels. We report here a first step towards understanding the principles of beta-sheet formation in membranes. In particular, we describe the properties of a simple hydrophobic hexapeptide, acetyl-Trp-Leu5 (AcWL5), that assembles cooperatively into beta-sheet aggregates upon partitioning into lipid bilayer membranes from the aqueous phase where the peptide is strictly monomeric and random coil. The aggregates, containing 10 to 20 monomers, undergo a relatively sharp and reversible thermal unfolding at approximately 60 degreesC. No pores are formed by the aggregates, but they do induce graded leakage of vesicle contents at very high peptide to lipid ratios. Because beta-sheet structure is not observed when the peptide is dissolved in n-octanol, trifluoroethanol or sodium dodecyl sulfate micelles, aggregation into beta-sheets appears to be an exclusive property of the peptide in the bilayer membrane interface. This is an expected consequence of the hypothesis that a reduction in the free energy of partitioning of peptide bonds caused by hydrogen bonding drives secondary structure formation in membrane interfaces. But, other features of interfacial partitioning, such as side-chain interactions and reduction of dimensionality, must also contribute. We estimate from our partitioning data that the free energy reduction per residue for aggregation is about 0.5 kcal mol-1. Although modest, its aggregate effect on the free energy of assembling beta-sheet proteins can be huge. This surprising finding, that a simple hydrophobic hexapeptide readily assembles into oligomeric beta-sheets in membranes, reveals the potent ability of membranes to promote secondary structure in peptides, and shows that the formation of beta-sheets in membranes is more facile than expected. Furthermore, it provides a basis for understanding the observation that membranes promote self-association of beta-amyloid peptides. AcWL5 and related peptides thus provide a good starting point for designing peptide models for exploring the principles of beta-sheet formation in membranes.
Circular Dichroism↗
Potential angiogenic role of platelet-activating factor in human breast cancer.
This study investigated the presence of platelet-activating factor (PAF) in the lipid extracts of 18 primary breast carcinomas and 20 control breast tissues. The amount of PAF detected in breast carcinomas was significantly higher than in controls. The mass spectrometric analysis of PAF-bioactive lipid extract from breast carcinomas showed the presence of several molecular species of PAF, including C16-alkylPAF, C18-lysophosphatidylcholine (LPC), C16-LPC, lyso-PAF, and C16-acylPAF. The amount of bioactive PAF extracted from breast specimens significantly correlated with tumor vascularization revealed by the number of CD34-and CD31-positive cells. As C16-alkylPAF was previously shown to induce angiogenesis in vivo, we evaluated whether the thin layer chromatography-purified lipid extracts of breast specimens elicited neoangiogenesis in a murine model of subcutaneous Matrigel injection. The lipid extracts from specimens of breast carcinoma containing high levels of PAF bioactivity, but not from breast carcinomas containing low levels of PAF bioactivity or from normal breast tissue, induced a significant angiogenic response. This angiogenic response was significantly inhibited by the PAF receptor antagonist WEB 2170. T47D and MCF7 breast cancer cell lines, but not an immortalized nontumor breast cell line (MCF10), released PAF in the culture medium. A significant in vivo neoangiogenic response, inhibited by WEB 2170, was elicited by T47D and MCF7 but not by MCF10 culture medium. These results indicate that an increased concentration of PAF is present in tumors with high microvessel density and that PAF may account for the neoangiogenic activity induced in mice by the lipid extracts obtained from breast cancer. A contribution of PAF in the neovascularization of human breast cancer is suggested.
Aged↗
Infrared spectroscopy of supported lipid monolayer, bilayer, and multibilayer membranes.
Cecropin A was examined in supported monolayer, bilayer, and multibilayer lipid membranes using attenuated total internal reflection Fourier-transform infrared spectroscopy. The spectral features provide an abundance of information about the conformation and orientation of the peptide, as well as about the effects of the peptide on lipid order. In this case, they serve to contrast results from the three preparations. The results of monolayer and bilayer studies are generally similar, although differences in the nature of the membranes appear to cause minor changes in the conformation and orientation of the peptide. The results of the multibilayer studies are different in many respects from those of the monolayer and bilayer studies, suggesting that fundamentally different peptide-lipid interactions occur in multibilayers.
Chemical Phenomena↗