PubMed Health⌕ Search

Biomedical subjects

S Coppola

Publications and source records attributed to S Coppola.

At least 19 recordsLinked to original sources
PubMed1999

Magnetic fields increase cell survival by inhibiting apoptosis via modulation of Ca2+ influx.

Static magnetic fields with intensities starting from 6 gauss (6x10(-4) tesla, T) were found to decrease in an intensity-dependent fashion, reaching a plateau at 6 x 10(-3) T, the extent of cell death by apoptosis induced by several agents in different human cell systems. This is not due to a change in the mode of cell death (i.e., to necrosis) or to a delay of the process itself; rather, the presence of magnetic fields allows the indefinite survival and replication of the cells hit by apoptogenic agents. The protective effect was found to be mediated by the ability of the fields to enhance Ca2+ influx from the extracellular medium; accordingly, it was limited to those cell systems where Ca2+ influx was shown to have an antiapoptotic effect. Magnetic fields thus might interfere with human health by altering/restoring the equilibrium between cell death and proliferation; indeed, the rescue of damaged cells may be the mechanism explaining why magnetic fields that are not mutagenic per se are often able to increase mutation and tumor frequencies.

Animals↗
PubMed1998

Random amplified polymorphic DNA and amplified ribosomal DNA spacer polymorphism: powerful methods to differentiate Streptococcus thermophilus strains.

Streptococci from different collections and dairy materials were characterized by conventional and molecular methods. After amplification of the 16S-23S rDNA spacer region, all the strains referable to the genus Streptococcus exhibited a single polymerase chain reaction (PCR) product, allowing their differentiation from enterococci. Cleaving this PCR product with Hae III, two different restriction patterns could be observed, allowing Streptococcus salivarius DSM 20560T, Strep. thermophilus NCDO 822 and two strains of Streptococcus spp. to be gathered in one group and all the other strains in another. In order to achieve strain typing, all the cultures were investigated by random amplified polymorphic DNA (RAPD)-PCR analysis employing two selected primers. The results were treated by cluster analysis, appearing significantly consistent with both the taxonomic position and the origin of the strains. Pulsed-field gel electrophoresis (PFGE) of Sma I digests of the genomic DNA from 11 representative strains with decreasing levels of RAPD similarity allowed their diversity to be confirmed, even though RAPD-PCR proved to be less discriminating than PFGE analysis. The results are discussed with reference to the capability of the analytical procedures used to aid both identification and strain typing of streptococci, as well as the taxonomic structure of the species Strep. thermophilus.

Bacterial Typing Techniques↗
PubMed1998

Effect of leavening microflora on pizza dough properties.

Fourteen different starter cultures containing one strain of Saccharomyces cerevisiae with and without individual or combinations of lactic acid bacteria (Lactobacillus plantarum, Lact. sanfrancisco, Enterococcus faecium, Leuconostoc mesenteroides) were employed to investigate the role of leavening microflora on the properties of pizza doughs. Microbiological, chemical and physical characteristics of doughs prepared with the same flour and under the same processing conditions were determined. Leavening times and acidification properties depended on the microbial association used. The proportions of lactic and acetic acid produced by lactic acid bacteria were consistent with the metabolic properties of the strains employed. The bacteria/yeast ratios arising from microbial counts at the end of the leavening process were always lower in comparison to sour- or bread-doughs. The size of the yeast population did not change much, while bacteria showed from one to four duplications. Rheologically, the fermented doughs could only be significantly distinguished from the control dough with regard to the elastic modulus. Principal Component Analysis was applied to the acidimetric data. The scattergram of the two principal components effectively discriminated 13 of the 14 pizza dough types.

Acetic Acid↗
PubMed1998

Fluconazole susceptibility and strain variation of Candida albicans isolates from HIV-infected patients with oropharyngeal candidosis.

Over a 16 month period we conducted a prospective study in a cohort of 45 HIV-positive patients to detect the development of resistance to fluconazole and to analyse the epidemiology of oropharyngeal candidosis (OPC). Each episode was treated with fluconazole 100 mg/day po for 10 days. All yeast isolates were tested for their in-vitro susceptibility to fluconazole. Multiple strains of Candida albicans simultaneously isolated from a given patient were typed by electrophoretic karyotyping. Overall, 106 episodes of OPC were diagnosed among the 45 patients: 18/45 patients (40%) had only one episode, 11/45 (24%) had two episodes, and the remaining 16/45 (36%) had three or more episodes (range 3-7). Cure (complete resolution of signs and symptoms and negative post-treatment cultures) and improvement (complete resolution of signs and symptoms but positive post-treatment cultures) were observed in 30/106 (28%) and 69/106 (65%) episodes of OPC, respectively. Failure (absence of improvement or exacerbation of signs and symptoms) was observed in seven episodes (7%) from four patients. In two of these four patients a significant and progressive increase in fluconazole MICs was observed: from 0.25 to 16 mg/L in one patient, and from < or = 0.125 to 32 mg/L in the second one. Tests on multiple colonies from individual isolation plates showed that it was not unusual to obtain different fluconazole MICs, indicating that, in order to avoid misleading results, one should perform in-vitro susceptibility testing by using a multiple colony inoculum rather than an inoculum made from a single colony. A total of 213 strains of C. albicans isolated from seven patients who suffered from four or more episodes of OPC through the course of the study were typed by electrophoretic karyotyping. Five individuals (71%) were infected with yeasts with only one DNA type, while the other two patients showed the presence of two or three different DNA types. The simultaneous presence of multiple types was found only in one of the seven subjects. Our data confirm the efficacy of fluconazole 100 mg/day for the treatment of OPC in HIV patients. Isolation of fluconazole-resistant strains of C. albicans with this regimen is rare. The vast majority of HIV patients are infected with a unique strain of C. albicans throughout each episode of infection. A minority of patients, however, can harbour strains of C. albicans with variable patterns of fluconazole susceptibility simultaneously.

AIDS-Related Opportunistic Infections↗
PubMed1998

Rescue of cells from apoptosis by inhibition of active GSH extrusion.

Cells induced to apoptosis extrude glutathione in the reduced form concomitantly with (U937 cells) or before (HepG2 cells) the development of apoptosis, much earlier than plasma membrane leakage. Two specific inhibitors of carrier-mediated GSH extrusion, methionine or cystathionine, are able to decrease apoptotic GSH efflux across the intact plasma membrane, demonstrating that in these cell systems GSH extrusion occurs via a specific mechanism. While decreasing GSH efflux, cystathionine or methionine also decrease the extent of apoptosis. They fail to exert anti-apoptotic activity in cells previously deprived of GSH, indicating that the target of the protection is indeed GSH efflux. The cells rescued by methionine or cystathionine remained viable after removal of the apoptogenic inducers and were even able to replicate. This shows that a real rescue to perfect viability and not just a delay of apoptosis is achieved by forcing GSH to stay within the cells during apoptogenic treatment. All this evidence indicates that extrusion of reduced glutathione precedes and is responsible for the irreversible morphofunctional changes of apoptosis, probably by altering the intracellular redox state without intervention of reactive oxygen species, thus giving a rationale for the development of redox-dependent apoptosis under anaerobic conditions.

Apoptosis↗
PubMed1998

Pregnancy-associated breast cancer.

Pregnancy-associated breast cancer, which is defined as all breast cancer diagnosed during pregnancy or within the following year, is a relatively rare finding. Due to the particular difficulties in the diagnosis of breast cancer during this period, pregnant women tend to present more advanced disease at diagnosis. Four cases of pregnancy-associated breast cancer referred to our Institute are described as a contribution to the knowledge of this disease.

Adult↗
PubMed1997

Partial recovery of in vivo function by improved incubation conditions of isolated renal proximal tubule. I. Change of amiloride-inhibitable K+ conductance.

Isolated microperfused rabbit renal proximal tubule S2 segments, if incubated in conventional substrate containing HCO3- Ringer solution, exhibit lower cell membrane potentials (Vb) and elevated intracellular Na+ concentrations ([Na]i) compared to rat tubules in vivo. Assuming that these and other differences reflect insufficient metabolic and/or hormonal stimulation of the cells, we have used microelectrode techniques to test whether improving substrate supply and applying norepinephrine (NE, to compensate for the missing nerve supply) reverts Vb and [Na]i to values observed in vivo. Application of D-glucose (5.5 mmol/l) and additional application of pyruvate, lactate, or L-alanine (each 10 mmol/l), or bathing the tubules in Dulbecco's modified Eagle's tissue culture medium (DMEM) significantly increased Vb and, whenever tested, reduced [Na]i as compared to substrate-free or D-glucose-containing control solution and these effects could be prevented - as tested in the case of pyruvate - by inhibition of the Na/K pump with ouabain. However, high concentrations of acetate, beta-hydroxybutyrate, or L-glutamine had no significant effect. The largest effect was obtained with joint application of DMEM and NE (10 micromol/l) which increased Vb from -42.8 +/- 1.3 mV (SEM) to -55.3 +/- 2.5 mV (n = 11). Interestingly we noticed that under the latter conditions the Vb response to bath application of 1 mmol/l amiloride virtually disappeared, i.e. it changed from a depolarization of +14.6 +/- 1.4 mV (in D-glucose Ringer solution) to +0.6 +/- 0.7 mV (in DMEM plus NE) (n = 8), with some tubules showing even a small hyperpolarization. The latter implies partial restoration of the in vivo behaviour, since in experiments on rat proximal tubules in vivo amiloride regularly hyperpolarized the cells (by -3.4 +/- 0.76 mV, n = 5). Obviously under conventional in vitro conditions an amiloride-inhibitable K+ conductance is activated which is inactive in vivo and also inactivates under improved conditions in vitro. In agreement with observations reported in the subsequent publication our results demonstrate that isolated proximal tubules undergo functional alterations which may be largely prevented by improved metabolic and stimulatory incubation conditions.

Amiloride↗
PubMed1997

Characterization of strains of Leuconostoc mesenteroides by analysis of soluble whole-cell protein pattern, DNA fingerprinting and restriction of ribosomal DNA.

Of 215 leuconostocs isolated from field grass, natural whey cultures and water-buffalo milk, 178 were identified as Leuconostoc mesenteroides ssp. mesenteroides while 37 strains could not be identified. Biochemical characterization allowed seven groups to be defined. Representative strains of each group and different habitat and nine reference strains were selected for further analyses. Protein profiles appeared suitable for species discrimination, but did not differentiate between the three subspecies of Leuc. mesenteroides. The technique also showed some differences among equivocal strains. DNA fingerprinting for most strains of Leuc. mesenteroides ssp. mesenteroides examined showed a different restriction pattern from that of the type strain. Ribotyping was not useful for discriminating species and subspecies of the genus Leuconostoc: Leuc. mesenteroides ssp. mesenteroides and ssp. dextranicum showed the same ribopattern as Leuc. lactis while Leuc. mesenteroides ssp. cremoris exhibited a pattern distinct from all the other species examined. On the basis of ARDRA-PCR, two main groups could be distinguished: the larger group included Leuc. mesenteroides, Leuc. lactis, Leuc. pseudomesenteroides and some unidentifiable strains; the second one included Leuc. citreum, Leuc. fallax, Weissella paramesenteroides and some unidentified strains.

Animals↗
PubMed1996

Protease involvement in fodrin cleavage and phosphatidylserine exposure in apoptosis.

A detailed kinetic analysis of three extranuclear end points of apoptosis, phosphatidylserine exposure, alpha-fodrin degradation, and plasma membrane blebbing, was performed and compared with nuclear fragmentation and the activation of the interleukin-1beta-converting enzyme (ICE)-like proteases in Jurkat T lymphocytes stimulated by anti-Fas monoclonal antibody (anti-Fas mAb) and in monocytic U937 cells stimulated by tumor necrosis factor (TNF) and cycloheximide. Phosphatidylserine exposure was quantitated by plasma clotting time, as well as annexin V-fluorescein isothiocyanate binding, and the ICE-like protease activity was examined by the cleavage of a specific fluorogenic peptide substrate Ac-Asp-Glu-Val-Asp-amino-4-methylcoumarin. VAD-chloromethylketone (VAD-cmk), an inhibitor of ICE-like proteases, effectively inhibited ICE-like activity in both cell types studied, whereas the calpain inhibitor calpeptin was ineffective. VAD-cmk also effectively inhibited all three extranuclear events, as well as nuclear fragmentation, in Jurkat cells stimulated by anti-Fas monoclonal antibody, indicating that ICE-like proteases play an important role in the regulation of this apoptotic system. Calpain inhibitors were ineffective in this system. TNF-induced extranuclear and nuclear changes in U937 cells were inhibited by calpeptin but were not as effectively inhibited by VAD-cmk as in Jurkat cells. This suggests that ICE-like enzymes predominate in anti-Fas monoclonal antibody-stimulated Jurkat cells, whereas proteases affected by calpain inhibitors as well as the ICE-like enzymes are involved in the signaling of apoptotic events in TNF-induced U937 cells. Importantly, the two apoptotic systems seem to be regulated by different proteases.

Antibodies, Monoclonal↗
PubMed1996

Presence of non-functional nisin genes in Lactococcus lactis subsp. lactis isolated from natural starters.

Sixty-four lactococcal strains isolated from natural whey starters were screened for the presence of the nisin structural gene by polymerase chain reaction. Seven of them showed a specific PCR product of 320 bp; only two produced antagonistic activity and were resistant to nisin. Southern blots of SmaI-digested DNA from PCR-positive strains hybridized with a nisA probe displayed a location of the gene on different SmaI fragments. Among PCR-positive strains, nisin producers showed specific transcript after reverse transcriptase-PCR, as well as some non-nisin-producing strains. The RT-PCR product could not be shown in one non-nisin-producing PCR-positive strain.

Animals↗
PubMed1996

Multiple pathways for apoptotic nuclear fragmentation.

We analyzed the ultrastructure of apoptotic nuclear fragmentation in U937 cells treated with many different apoptogenic agents. We found that this characteristic apoptotic feature can be achieved through multiple alternative pathways, depending on the apoptogenic inducer, leading to slightly different final nuclear morphologies. In most instances, the irregularly shaped nucleus of U937 rounds up; then, chromatin condenses at the nuclear periphery. Condensed chromatin can form protruding patches, which eventually bud from the nucleus in sealed vesicles through a process which is actin-dependent, since it could be blocked by cytochalasins. Alternatively, chromatin condenses in tiny, nonprotruding crescents, and a cleavage in the nuclear sap forms, beginning from the inner nuclear membrane and growing inward, thus splitting the nucleus. In U937 induced to apoptosis by hydrogen peroxide in the presence of ADP-ribosylation inhibitors, the nuclei fragment in many vesicles before chromatin even begins to condense: chromatin condensation probably occurs as a consequence. While all the apoptotic morphologies described above evolve from interphase cells, a peculiar apoptotic morphology, possibly deriving from mitotic cells, is detected upon oxidative stress, recalling the formation of micronuclei by clastogenic treatments; it shows partially membrane-bound chromatin patches, which look midway between condensed chromosomes and apoptotic condensed chromatin. The existence of these multiple pathways for nuclear fragmentation may indicate an evolutionary convergence, suggesting that this event may play an important physiological role in apoptosis.

Adenosine Diphosphate Ribose↗
PubMed1996

On the mechanism of bicarbonate exit from renal proximal tubular cells.

We compare here the results of electrophysiological measurements on proximal tubular cells performed on rat kidney in vivo and on isolated rabbit and rat tubules in vitro. Based on different effects of carbonic anhydrase inhibitors in the in vivo and in vitro preparation, we conclude that NaHCO3 cotransport across the basolateral cell membrane functions as Na(+)-CO3(2-)-HCO3- cotransport in vivo, but as Na(+)-HCO3(-)-HCO3- cotransport in the classical in vitro preparation. The former, but not the latter, transport mode is characterized by generation of local disequilibrium pH/CO3(2-) concentrations that oppose fluxes if membrane-bound carbonic anhydrase is inhibited. In support of this conclusion, we find that overall transport functions with a HCO3- to Na+ stoichiometry of 3:1 in vivo (since each transported CO3(2-) eventually generates 2 HCO3- ions), but 2:1 in vitro. This has been deduced from various measurements, among them super-Nernstian and reverse nernstian, potential responses to changing ion concentrations which are characteristic of obligatorily coupled cation-anion cotransporters, but are not known in classical electrochemistry. The different transport modes in vivo and in vitro suggest that isolated proximal tubules have functional deficits compared to proximal tubules in vivo.

Animals↗
PubMed1996

Behaviour of Listeria monocytogenes during the traditional manufacture of water-buffalo Mozzarella cheese.

The behaviour of a four-strains mixture of Listeria monocytogenes (strains Scott A, V7, OH and Cal) during the traditional manufacture of water-buffalo Mozzarella cheese was investigated at two levels of inoculation: ca 10(5) and 10(3) cfu ml-1 of vat milk. No significant change in Listeria counts was observed during the curd ripening (4.0-4.5 h), at the end of which the pH ranged between 4.83 and 4.91. A decrease of about 2 log was observed after stretching of the curd in hot water (95 degrees C), followed by complete elimination of Listeria after 48 and 24 h of storage of the final cheese in the conditioning liquid (skim water resulting from the stretching, pH ca 4.0) with initial high and low contamination of the cheese milk respectively. Results also indicated that a 1.7 log reduction of L. monocytogenes could be achieved during the preparation of the natural whey culture utilized as starter in cheesemaking.

Cheese↗
PubMed1996

Topical thymopentin therapy in HIV positive patients with recurrent oral candidiasis: a pilot study.

Oral candidiasis frequently occurs in HIV-positive patients especially in those with advanced disease. To date, common anti-mycotic drugs are unable to prevent relapses and alternative therapy is necessary to reduce disabling effects. With the aim of verifying whether thymic hormone extract may be efficacious in these subjects, we enrolled 10 HIV-positive patients with recurrent and/or persistent oral candidiasis to be treated with thymopentin (oral inhalations). All patients benefited from the topical use of thymopentin, and in all cases there was marked increase in salivary secretory IgA which possibly accounted for the candidiasis improvement.

AIDS-Related Opportunistic Infections↗
PubMed1996

[Screening for carcinoma of the cervix today].

A revision of the more recent literature has been made in the order to establish which are, actually, the "gold standard" procedures in the planning out and the management of screening programs for cervical cancer. The problem of the false negatives responses, which make necessary the adoption of adequate reporting systems and quality control programs, is relevant. A centralized and "organized" screening policy, involving most of the female population, is also mandatory, keeping in the mind the amount of work for the public health services. The ultimate goal is to assure a "cover" percentage higher than the actual levels, reaching an acceptable balance in terms of cost-efficiency.

False Negative Reactions↗
PubMed1995

Protease inhibitors block apoptosis at intermediate stages: a compared analysis of DNA fragmentation and apoptotic nuclear morphology.

The possible correlation between DNA digestion and changes in nuclear morphology in apoptosis was studied by blocking the apoptotic process at intermediate stages. The apoptogenic action of three drugs: etoposide, puromycin, tributyltin, was contrasted with protease inhibitors with different specificity on U937 cells. The inhibitors interfered with the development of the apoptotic features without shifting cell death to necrosis: treated cells showed abnormal morphologies, which could be recognized as intermediate stages of apoptosis; accordingly, DNA analysis showed an inhibitor-dependent block of the apoptotic DNA digestion. The comparison between size of DNA fragments and nuclear morphology suggested the following correlations: loss of normal nuclear shape with the appearance of a > or = 2 Mb DNA band; ongoing chromatin condensation with the progressive DNA digestion up to 50 kb; nuclear fragmentation with DNA laddering. Protease inhibitors in etoposide-treated cells did not allow the formation of 700-300 kb fragments, suggesting that they possibly derive from a cell-mediated effect.

Apoptosis↗