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Biomedical subjects

L Esposito

Publications and source records attributed to L Esposito.

At least 37 records · Page 2Linked to original sources
PubMed2001

Hematological and molecular analysis of beta-thalassemia and Hb Lepore in Campania, Italy.

This epidemiological study was based on a hematological and a molecular analysis of 310 heterozygous beta thalassemic and 75 carriers of Hb Lepore out of 3,000 microcythemic subjects from the Campania region of Italy. The molecular analysis of beta chains and the deltabeta hybrid gene has shown different beta chain defects, but only the Hb Lepore-Boston-Washington type in association with haplotypes I and V. The prevalence and distribution of these molecular defects in Campania show that they are linked to historical events and to the geographical characteristics of this region.

Cluster Analysis↗
PubMed2001

Cytokeratins as markers of follicular differentiation: an immunohistochemical study of trichoblastoma and basal cell carcinoma.

Trichoblastoma(s) (TB) are benign neoplasms of follicular differentiation frequently found in nevus sebaceus. Many morphologic features are shared with nodular basal cell carcinoma(s) (BCC), sometimes rendering the differential diagnosis difficult. Because both neoplasms can simulate components of mature hair follicles histologically, we attempted to corroborate this by immunohistochemical examination of cytokeratins and hair keratins differentially expressed in the hair follicle. Trichoblastoma(s) and BCC showed homogenous expression of CK14 and CK17. The innermost cells of the tumor nodules in all TB and in 72% of BCC were positive for CK6hf. Using a specific CK15 antibody, 38% of TB showed a focal labeling and all BCC remained negative; 70% of TB and 22% of BCC expressed CK19. CK8 was expressed by numerous Merkel cells present in all TB but in none of the BCC examined. All type I and II hair keratins tested, (especially hHa1, hHa5, and hHa8) remained negative in all tumors examined. Trichoblastoma(s) and BCC show consistent expression of CK6hf, CK14, and CK17; variable expression of CK15 and CK19; and absence of hair keratins. This indicates a differentiation toward the outer root sheath epithelium or the companion layer and not toward the inner root sheath, matrix, or cortex.

Biomarkers, Tumor↗
PubMed2000

The ultrahigh resolution crystal structure of ribonuclease A containing an isoaspartyl residue: hydration and sterochemical analysis.

Crystals of the deamidated form of bovine pancreatic ribonuclease which contains an isoaspartyl residue in position 67 diffract to 0. 87 A at 100 K. We have refined the crystallographic model using anisotropic displacement parameters for all atoms to a conventional crystallographic residual R=0.101 for all observed reflections in the resolution range 61.0-0.87 A. The ratio observations/parameters is 7.2 for the final model. This structure represents one of the highest resolution protein structures to date and interestingly, it is the only example containing more than one molecule in the asymmetric unit with a resolution better than 1.0 A. The non-crystallographic symmetry has been used as a validation check of the geometrical parameters and it has allowed an estimate for an upper limit of errors associated with this high resolution model. In the present structure it was possible to obtain a more accurate picture of the active site whose electron density was not clearly interpretable in the previous 1.9 A resolution structure. In particular, the P1 site is alternatively occupied either by a sulphate anion or by a water molecule network. Most of hydrogen atoms were visible in the electron density maps, including those involved in C(alpha)-H(alpha).O interactions. Analysis of protein-solvent interactions has revealed the occurrence of an extensive cluster of water molecules, predominantly arranged in pentagonal fused rings and surrounding hydrophobic moiety of side-chains. Finally, in spite of the limited sample of residues, we have detected a clear dependence of backbone N-C(alpha)-C angle on residue conformation. This correlation can be fruitfully used as a valuable tool in protein structure validation.

Amides↗
PubMed2000

Protection of intrinsic nerves of guinea-pig detrusor strips against anoxia/glucopenia and reperfusion injury by taurine.

There is ample evidence that ischaemia is associated with partial denervation of the detrusor muscle and that this is responsible for much of its abnormal contractile behaviour, resulting in bladder dysfunction (instability). In guinea-pig nerves are very susceptible to the ischaemic damage as compared to the muscle cells. The purpose of this study was to assess the neuroprotection afforded by taurine on guinea-pig detrusor under ischaemic-like conditions. Guinea-pig detrusor strips were subjected for 60 min to ischaemic-like conditions, followed by 150 min reperfusion. Intrinsic nerves underwent every 30 min electrical field stimulation (EFS) by 5-s trains of square voltage pulses of 0.05 ms duration (15 Hz, 50 V). Detrusor strips were perfused with 0.1, 1, 3 or 10 mM taurine during the ischaemia-like exposure and the first 30 min of reperfusion. Taurine (1 and 3 mM) significantly improved the response of the strips to EFS both at the end of ischaemia and reperfusion. On the contrary, neither 0.1 nor 10 mM taurine had significant effects. It is concluded that taurine can partially counteract the ischaemia-reperfusion injury in the guinea-pig urinary bladder.

Aminoethylphosphonic Acid↗
PubMed2000

Experimental evidence for the correlation of bond distances in peptide groups detected in ultrahigh-resolution protein structures.

The structural analysis of a deamidated derivative of ribonuclease A, determined at 0.87 A resolution, reveals a highly significant negative correlation between CN and CO bond distances in peptide groups. This trend, i.e. the CO bond lengthens when the CN bond shortens, is also found in seven out of eight protein structures, determined at ultrahigh resolution (<0.95 A). In five of them the linear correlation is statistically significant at the 95% confidence level. The present findings are consistent with the traditional view of amide resonance and, although already found in small peptide structures, they represent a new and important result. In fact, in a protein structure the fine details of the peptide geometry are only marginally affected by the crystal field and they are mostly produced by intramolecular and solvent interactions. The analysis of very high-resolution protein structures can reveal subtle information about local electronic features of proteins which may be critical to folding, function or ligand binding.

Carbon↗
PubMed2000

Evaluation of single nucleotide polymorphism typing with invader on PCR amplicons and its automation.

Large-scale pharmacogenetics and complex disease association studies will require typing of thousands of single-nucleotide polymorphisms (SNPs) in thousands of individuals. Such projects would benefit from a genotyping system with accuracy >99% and a failure rate <5% on a simple, reliable, and flexible platform. However, such a system is not yet available for routine laboratory use. We have evaluated a modification of the previously reported Invader SNP-typing chemistry for use in a genotyping laboratory and tested its automation. The Invader technology uses a Flap Endonuclease for allele discrimination and a universal fluorescence resonance energy transfer (FRET) reporter system. Three hundred and eighty-four individuals were genotyped across a panel of 36 SNPs and one insertion/deletion polymorphism with Invader assays using PCR product as template, a total of 14,208 genotypes. An average failure rate of 2.3% was recorded, mostly associated with PCR failure, and the typing was 99.2% accurate when compared with genotypes generated with established techniques. An average signal-to-noise ratio (9:1) was obtained. The high degree of discrimination for single base changes, coupled with homogeneous format, has allowed us to deploy liquid handling robots in a 384-well microtitre plate format and an automated end-point capture of fluorescent signal. Simple semiautomated data interpretation allows the generation of approximately 25,000 genotypes per person per week, which is 10-fold greater than gel-based SNP typing and microsatellite typing in our laboratory. Savings on labor costs are considerable. We conclude that Invader chemistry using PCR products as template represents a useful technology for typing large numbers of SNPs rapidly and efficiently.

Base Sequence↗
PubMed2000

Effect of deamidation on folding of ribonuclease A.

The folding of ribonuclease A (RNase A) has been extensively studied by characterizing the disulfide containing intermediates using different experimental conditions and analytical techniques. So far, some aspects still remain unclear such as the role of the loop 65-72 in the folding pathway. We have studied the oxidative folding of a RNase A derivative containing at position 67 the substitution Asn --> isoAsp where the local structure of the loop 65-72 has been modified keeping intact the C65-C72 disulfide bond. By comparing the folding behavior of this mutant to that of the wild-type protein, we found that the deamidation significantly decreases the folding rate and alters the folding pathway of RNase A. Results presented here shed light on the role of the 65-72 region in the folding process of RNase A and also clarifies the effect of the deamidation on the folding/unfolding processes. On a more general ground, this study represents the first characterization of the intermediates produced along the folding of a deamidated protein.

Amides↗
PubMed2000

Pyramidalization of backbone carbonyl carbon atoms in proteins.

The high accuracy of X-ray analyses at atomic resolution is now able to display subtle deformations from standard geometry of building blocks in proteins. From the analysis of nine ultra-high resolution protein structures, we derived the first experimental evidence that a significant pyramidalization at the main-chain carbonyl carbon atom occurs in proteins. Our findings also show that this pyramidalization is related to the main-chain psi torsion angle. The carbonyl carbon atoms of residues that adopt alphaR and extended conformations show a clear preference for positive and negative pyramidalization, respectively. The agreement between our data and those previously obtained from small molecule structures demonstrates that carbon pyramidalization is an intrinsic property of the peptide structure. Although small in magnitude, the pyramidalization is well preserved in the complex folded state of a macromolecular structure that results from the interplay of many different forces. In addition, this property of the peptide group may have interesting implications for the enzymatic reactions involving the carbonyl carbon atoms.

Animals↗
PubMed1999

Diagnosis of renal disease at the beginning of the 20th century.

At the beginning of this century, the diagnosis of various renal diseases was made with relative accuracy although neither plasma markers of glomerular filtration nor renal biopsy nor imaging were available. Renal edema was identified by high albuminuria, hyalin cylinders, high urine density and oliguria. Renal hematuria was detected by cylinders of erythrocytes. Hallmarks of chronic renal insufficiency, recognized at autopsy by atrophic kidneys, were hyposthenuria, polyuria and slight albuminuria without edema associated with arterial hypertension, anemia, retinopathy and left ventricular hypertrophy. The detection of increased plasma volume in experimental toxic nephritis by St. Moscati proposed the underlying mechanism of arterial hypertension. Experimental and clinical research in the preinsulin era indicated the central role of the kidney in the functional alterations induced by diabetes. Indeed, glucosuria was known to appear only when glycemia was relatively high. The kidney appeared enlarged and hyperemic, i.e. the so-called glomerular hyperfiltration. Glucosuria was directly correlated with diuresis but it markedly decreased in renal insufficiency. In diabetes complicated by nephropathy, tolerance to carbohydrates improved. Correction of glucosuria by dietary treatment was followed by a prompt rise in body weight, due to retention that counterbalanced the previous losses. Diabetic ketoacidosis, determined by the measurement of urinary ketonic body excretion, was treated with sodium bicarbonate (30-50 g/day in severe acidosis) up to achieving an alkaline urine pH. It was known that high doses of sodium bicarbonate might induce edema which gradually disappeared with a reduction in the alkaline administration. Clinical significance of sodium balance was, in fact, recognized: the external NaCl balance between alimentary ingestion and urinary excretion was neutral in normal conditions and became positive at high body temperature or negative during reabsorption of exudates.

Animals↗
PubMed1998

Protein crystal growth in the Advanced Protein Crystallization Facility on the LMS mission: a comparison of Sulfolobus solfataricus alcohol dehydrogenase crystals grown on the ground and in microgravity.

Crystals of alcohol dehydrogenase from Sulfolobus solfataricus were grown in the Advanced Protein Crystallization Facility during the Life and Microgravity Sciences Spacelab mission on the US Space Shuttle. Large diffracting crystals were obtained by dialysis, whereas only poor-quality crystals were obtained by vapour diffusion. The quality of both the microgravity and ground-based crystals was analysed by X-ray diffraction. There was some improvement in terms of size and diffraction resolution limit for the microgravity crystals. However, the twinning observed in the Earth-grown crystals was also present for those grown in microgravity.

Alcohol Dehydrogenase↗