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Biomedical subjects

A Esposito

Publications and source records attributed to A Esposito.

At least 37 records · Page 2Linked to original sources
PubMed2002

Investigation of naphtalene sulfonate compounds sorption in a soil artificially contaminated using batch and column assays.

In the present work desorption tests of an artificially contaminated soil by naphatelene sulphonated compounds have been carried out by soil washing realised by water at different pH: Naphtalene-1,5-disulfonic acid (1-5 NDS), 2-naphthol-6,8 disulphonic acid (G-acid) and sodium beta-naphtalene-sulphonate (beta-salt) have been selected as more representative organic compounds present in the ex industrial site of ACNA (Cengio, SV, Italy) in which very serious contamination levels of several pollutants are present both in the soils and surface waters. Equilibrium batch tests have been carried out in order to find the best operative condition in column washing tests. The obtained results can be considered very preliminary but useful to arrange a next experimental work that will be realised on real contaminated soils.

Adsorption↗
PubMed2002

Energy dependence of TLD-300 response from 6 keV up to 1250 keV.

The energy dependence of the response function S(E), of CaF2:Tm (TLD-300) thermoluminescent material (3.2 x 3.2 x 0.90 mm3 ribbons) was measured from 6 keV up to 1250 keV (60Co) using 55Fe, 137Cs and 60Co gamma ray sources as well as X ray ISO reference beams. To the best knowledge of the authors the data for energies below 45 keV are reported for the first time. The S(E) function was also calculated in the energy range from 1 keV up to 20 MeV and compared with the experimental data relative to the total glow curve. The comparison shows good agreement from 1250 keV down to 40 keV. At lower energy the discrepancy increases. This is interpreted in terms of the X ray attenuation within the thickness of TLD-300. Finally, measurements point out the effects of different reading and annealing treatments on the measured function S(E).

Calcium Fluoride↗
PubMed2002

Expression of sarco(endo)plasmic reticulum Ca(2+)-ATPase slow (SERCA2) isoform in regenerating rat soleus skeletal muscle depends on nerve impulses.

We have examined the influence of innervation on the expression of different isoforms of sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) in regenerating rat slow twitch muscle. The process of degeneration/regeneration was induced by injection of bupivacaine into rat soleus muscle under four different conditions: (1) in the presence of intact motor nerves, (2) after surgical denervation, (3) with nerve impulse conduction blocked by the Na(+)-channel blocker tetrodotoxin (TTX), and (4) with the axoplasmic flow blocked by vinblastine. Expression of SERCA isoforms was visualized by immunohistochemical and Western blot analysis. In regenerating innervated muscle, SERCA1, the isoform normally expressed in fast twitch fibres, was present after 5 days and was then progressively replaced by SERCA2, the isoform typical of slow twitch fibres. The maximum Ca(2+) uptake, measured in single skinned fibres regenerating for 10-21 days, was similar to that of slow adult fibres and significantly lower than that of fast adult fibres. Denervation or TTX treatment prevented the expression of the SERCA2 isoform. Conversely, vinblastine did not affect the expression of SERCA isoforms. These data indicate that nerve impulses play a determinant role in the expression of the SERCA2 isoform.

Anesthetics, Local↗
PubMed2001

First stereocontrolled synthesis of (S)-cleonin and related cyclopropyl-substituted amino acids.

[reaction: see text]. Enantiomerically pure (S)-cleonin, a key component of the antitumor antibiotic cleomycin, was prepared starting from (R)-serine. The Kulinkovich cyclopropanation of the methyl ester of N-Cbz serine acetonide gave the hydroxycyclopropyl moiety. The amino alcohol region was further oxidized to amino acid. The Kulinkovich cyclopropanation allowed also the preparation of other non-natural substituted cyclopropylglycines.

Amino Acids↗
PubMed2001

Delayed glial cell death following wallerian degeneration in white matter tracts after spinal cord dorsal column cordotomy in adult rats.

The devastating consequences of spinal cord injury (SCI) result primarily from damage to long tracts in the spinal white matter. To elucidate the secondary injury processes occurring after SCI, we investigated the relationship between apoptosis and Wallerian degeneration in spinal white matter tracts. In the rat spinal cord, the corticospinal tract (CST) and the dorsal ascending tract (DAT) are separated from each other in the dorsal column and relay information in opposite directions. A dorsal column cordotomy at the eighth thoracic (T8) level simultaneously induces Wallerian degeneration in the CST caudal to and in the DAT rostral to the injury. Using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) method, we demonstrate that apoptosis occurred in areas of Wallerian degeneration in both tracts throughout the length of the cord segments studied (from T3 to T12). This delayed cell death, more apparent in the DAT, began at 7 days after injury and peaked at 14 days for the DAT and 28 days for the CST. Although a few TUNEL+ cells, slightly above the noninjury control level, were found in intact areas of both tracts, statistically significant differences in the number of TUNEL+ cells were found between the intact and the lesioned tract segments (CST, F < 0.01; DAT, F < 0.001). Within a particular spinal segment, a mean number of 64 and 939 TUNEL+ cells in the degenerating CST and DAT, respectively, were estimated stereologically at 14 days postinjury. TUNEL+ cells in degenerating tracts outnumber their intact counterparts by 3.8:1 in the CST and 4.1:1 in the DAT, although a statistically significant difference between the two was only found in the DAT at this time point (P < 0.05). Finally, we demonstrated that oligodendrocytes, the myelin-forming cells in the central nervous system, constitute at least a portion of the cells undergoing apoptosis within areas of Wallerian degeneration.

Animals↗
PubMed2001

Measurement of the mass attenuation coefficient for elemental materials in the range 6 < or = Z < or = 82 using X-rays from 13 up to 50 kev.

The mass attenuation coefficients for 22 high purity elemental materials (C, Al, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Rh, Pd, Ag, Cd, In, Ta, Pt, Au, Pb) were measured in the X-ray energy range from 13 up to 50 keV using a high purity germanium detector with thin (50 microm) Be window and a variable-energy X-ray source. The measured values are compared with the theoretical ones obtained using the XCOM code and data base, as well as with other experimental data showing a general agreement within +/- 5%. The mass attenuation cross-sections were thus derived and compared with other experimental data available on the 1988 NBS database of X-ray attenuation cross-sections. The agreement is always within +/- 8%, but for a few points the discrepancies are up to +/- 18%. The data analysis has also shown that some measurements performed at 50.65 keV as well as at 36.65 keV are to be considered as new data for most of the measured materials.

Journal Article↗
PubMed2001

Cardiac betaARK1 upregulation induced by chronic salt deprivation in rats.

The beta-adrenergic receptor (betaAR) kinase (betaARK1) is a G protein-coupled receptor kinase (GRK) that controls cardiac betaAR signaling via receptor phosphorylation, leading to desensitization. We have observed in mice that chronic isoproterenol administration results in increased myocardial levels of betaARK1 activity, suggesting that adrenergic activation can regulate cardiac betaARK1 expression. Thus, we evaluated left ventricular (LV) betaARK1 levels and activity in response to 3 weeks of a low-sodium (0.05%) diet, which is known to chronically activate the sympathetic nervous system. Wistar-Kyoto rats were subjected to either low or regular sodium (2%) intake. To prove the association of betaARK1 expression and low sodium-induced adrenergic activation, a group of rats was subjected to atenolol treatment (1 mg/kg per day) during the low-sodium diet. LV betaARK1 expression was assessed by protein immunoblotting and betaARK1 activity by in vitro GRK phosphorylation assays. We verified the LV protein levels of GRK5, which is abundantly expressed in the heart. A low-sodium diet reduced body weight and cardiac size so that the heart-to-body weight ratio did not change. On the contrary, low-sodium diet increased by 50% both LV betaARK1 protein (densitometry units: normal sodium, 26.5+/-0.9; low sodium, 35.7+/-1.6; P<0.05) and activity (fmol/mg per minute: normal sodium, 6.49+/-1.17; low sodium, 9.15+/-0.93; P<0.05). Atenolol treatment prevented the increase in both protein expression (low sodium plus atenolol, 27.6+/-5.33, P=NS versus normal sodium) and activity (6.54+/-1.19, P=NS versus normal sodium). GRK5 expression was not affected by a low-sodium diet (17.2+/-0.2 versus 18.4+/-0.4, P=NS). Our data indicate that cardiac betaARK1 is regulated by sympathetic action on betaARs as tested by reducing dietary salt and betaAR blockade.

Adrenergic beta-Antagonists↗
PubMed2001

[Guideline for the hemodialytic treatment of chronic uremia].

In this review we have summarized the guidelines on hemodialysis prescription and dose in order to attempt of simplify an issue often difficult to understand for the majority of physicians. In brief, we start from the results of National Cooperative Dialysis Study and then we describe the Urea Kinetic Model, the KT/V and the Protein Catabolic Rate (PCR). Simplified formulas to obtain KT/V and PCR are also reported. At the end, the modalities related to postdialytic blood samples and connected problems are described.

Chronic Disease↗
PubMed2000

Gene structure of human and mouse NKLAM, a gene associated with cellular cytotoxicity.

A novel gene involved in cytotoxicity, NKLAM [for "natural killer (NK) lytic-associated molecule"], has recently been identified in human NK cells. Its expression correlates with the cytolytic activity of both NK cells and cytotoxic T cells (CTLs); treatment of these cells with NKLAM-specific antisense oligonucleotides inhibits their cytotoxic function. NKLAM encodes a zinc finger protein that resides in NK cytolytic granules. Here, we identified a second human NKLAM transcript that differs from the original only at the 3' end, extending the open reading frame, and therefore encoding a significantly longer protein (731 residues compared with 587). The genomic structure of human NKLAM indicates that these two isoforms are products of alternative splicing. Both forms of NKLAM protein are expressed in NK cells, with the larger protein predominant. Human NKLAM cDNA was used to isolate mouse NKLAM from a C57BL/6 spleen cDNA library. There is a single NKLAM isoform in the mouse which shares over 89% nucleotide and 94% amino acid homology with the larger human form of NKLAM. The genomic organization of NKLAM is similar in both mouse and human. As with human NKLAM, mouse NKLAM mRNA is selectively expressed in CD8+ T cells NK cells, and activated peritoneal macrophages and further induced by cytokines that enhance the cytotoxic activity of these cells. These results indicate that human and mouse NKLAM are highly conserved both structurally and functionally, reinforcing the premise that this gene plays an important role in cellular cytotoxicity.

Amino Acid Sequence↗
PubMed2000

Approximation of continuous and discontinuous mappings by a growing neural RBF-based algorithm.

In this paper a neural network for approximating continuous and discontinuous mappings is described. The activation functions of the hidden nodes are the Radial Basis Functions (RBF) whose variances are learnt by means of an evolutionary optimization strategy. A new incremental learning strategy is used in order to improve the net performances. The learning strategy is able to save computational time because of the selective growing of the net structure and the capability of the learning algorithm to keep the effects of the activation functions local. Further, it does not require high order derivatives. An analysis of the learning capabilities and a comparison of the net performances with other approaches reported in literature have been performed. It is shown that the resulting network improves the approximation results reported for continuous mappings and for those exhibiting a finite number of discontinuities.

Algorithms↗
PubMed2000

Cellulose-based hydrogels as body water retainers.

In this work the possibility of using hydrogels as body water retainers for a therapeutic aid in pathologies such as oedemas of various origins was explored. For such a purpose, the material requires a good compatibility and a controlled swelling capacity without altering the body electrolyte homeostasis. The hydrogel was designed to meet the swelling requirements with the physiological constraints and its biocompatibility was assessed either in vitro or in vivo. Absorption tests were performed in order to define the swelling behavior by varying the pH and ion content of the external solution. The hydrogel swelling capacity was assessed in the presence of various solvents, in order to evaluate its absorption capacity in solutions similar to biological fluids. In addition, the capacity of the gel to modify electrolyte homeostasis by adsorbing ions such as calcium, potassium and sodium was tested. In order to assess the gel biocompatibility after contact of the hydrogel with intestinal cells, arachidonic acid relase was determined. No significant intracellular increase of free arachidonic acid was found in the cells after up to 2 h of contact with the gel. The results suggest that, as far as brief periods are concerned, the gel does not cause an inflammatory response in intestinal cells.

Journal Article↗
PubMed2000

Effects of fatigue on sarcoplasmic reticulum and myofibrillar properties of rat single muscle fibers.

Force decline during fatigue in skeletal muscle is attributed mainly to progressive alterations of the intracellular milieu. Metabolite changes and the decline in free myoplasmic calcium influence the activation and contractile processes. This study was aimed at evaluating whether fatigue also causes persistent modifications of key myofibrillar and sarcoplasmic reticulum (SR) proteins that contribute to tension reduction. The presence of such modifications was investigated in chemically skinned fibers, a procedure that replaces the fatigued cytoplasm from the muscle fiber with a normal medium. Myofibrillar Ca(2+) sensitivity was reduced in slow-twitch muscle (for example, the pCa value corresponding to 50% of maximum tension was 6.23 +/- 0.03 vs. 5.99 + 0.05, P < 0.01, in rested and fatigued fibers) and not modified in fast-twitch muscle. Phosphorylation of the regulatory myosin light chain isoform increased in fast-twitch muscle. The rate of SR Ca(2+) uptake was increased in slow-twitch muscle fibers (14.2 +/- 1.0 vs. 19.6 +/- 2. 5 nmol. min(-1). mg fiber protein(-1), P < 0.05) and not altered in fast-twitch fibers. No persistent modifications of SR Ca(2+) release properties were found. These results indicate that persistent modifications of myofibrillar and SR properties contribute to fatigue-induced muscle force decline only in slow fibers. These alterations may be either enhanced or counteracted, in vivo, by the metabolic changes that normally occur during fatigue development.

Animals↗
PubMed1999

Complete mutism after midbrain periaqueductal gray lesion.

Several neurophysiological studies have highlighted the role of the midbrain periaqueductal gray matter (PAG) in the initiation of vocalization in various animal species, from frogs to primates. With regard to humans, only two cases of complete mutism following a lesion to the PAG have been reported so far. This article describes a new case of a patient (GM) who, following an ischemic lesion to the periaqueductal gray region of the midbrain, presented with complete and irreversible mutism, though her language comprehension functions and her non-verbal expression capacity were preserved. This clinical case provides evidence that in humans the PAG also acts as a link between different vocalization-eliciting external and internal stimuli (which reach the PAG from sensory and emotional structures) and the vocal-motor coordinating mechanisms in the lower brain stem.

Aged↗
PubMed1999

Neglect-associated constructional disorders: a paradoxical phenomenon?

Five neglect patients without diffuse cognitive impairment or overt constructional disabilities were asked to bisect lines and rectangles and to copy rectangles bisected in their midplane. As a group, patients showed the usual rightward bias in bisecting lines and a milder deviation in bisecting horizontally-aligned rectangles, but showed a leftward deviation of the subjective midline in the copying task. This was due to drawing the left half shorter with respect to normal controls but three patients also drew the right half longer (the total length was the same as that of controls). A possible interpretation of rectangle copying results in these three patients is that they could create a representation of the stimulus to be copied accurately enough to reproduce its total length correctly but the subjective distribution of right and left space within that representation was unbalanced. However, specific experimental work is needed to verify why our patients with mild to moderate unilateral spatial neglect overrepresented the left side in a line bisection task and underrepresented it in a copying task.

Aged↗
PubMed1999

Degradation and transformation of a potential natural herbicide in three soils.

The methyl ester of fusaric acid (ME) is one of four toxins produced by the fungus Fusarium nygamai, which could be used as a natural herbicide against Striga hermonthica, a parasitic weed of sorghum and corn in a vast zone of West and Central Africa. A laboratory study was performed to measure the degradation of ME in three soil types and under different temperature and soil moisture conditions, so as to ascertain whether a single ME treatment would protect the crops against this weed during the critical phases of growth. The results show that the persistence in all soils and under all incubation conditions is long enough to protect the crops for the first week of growth, excluding the trial at 30 degrees C in the humic soil, where the half-life of 6 days would require more than one treatment. A degradation product of ME (butylpyridine, BP) was identified by gas chromatography/mass spectrometry and its degradation measured. The sum of ME and BP residues for the first 7 days was almost 100% of the applied compound in all soils and incubation conditions, thus indicating that BP may be the only transformation product of ME at this stage.

Africa↗
PubMed1999

Acoustical and perceptual study of gemination in Italian stops.

On the basis of theoretical considerations and results from acoustic and perceptual analyses, it is hypothesized that closure duration is the primary cue for gemination in Italian. Results of an acoustic analysis of a large number of single and geminate Italian utterances show two acoustic correlates of gemination: the length of the closure and the length of the vowel preceding the consonant. Other acoustic parameters were not systematically related to gemination. These results were validated perceptually. At the perceptual level, the above cues were used by the listeners in the geminate/nongeminate discrimination; however, closure duration played a major role. Moreover, it was found that the significant lengthening of consonant was only partially compensated by the shortening of the previous vowel and by a small lengthening of the geminate utterance with respect to the nongeminate one. This result suggests that speakers follow a sort of timing (rhythm) which is fixed in duration and depends on the number of syllables in the word: words with equal numbers of syllables do not change in utterance length, an elongated segment being partly compensated by the shortening of another. This process seems to be applied also perceptually suggesting that the timing (rhythm) of a language is also an auditory attitude.

Adult↗