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F Paoletti

Publications and source records attributed to F Paoletti.

At least 55 records · Page 3Linked to original sources
PubMed1995

Identification and conditions for selective expression of megakaryocytic markers in Friend erythroleukemia cells.

Friend murine erythroleukemia cells (MELCs) have been reevaluated in terms of their nature and potential pathways of differentiation. MELC induced with 5 mmol/L hexamethylene bisacetamide (HMBA), in addition to expression of known markers of the erythroid phenotype, were also found to exhibit traits of the megakaryocytic lineage. Erythroid differentiation was shown by the typical synthesis and accumulation of hemoglobin (Hb); megakaryoblastoid differentiation of MELCs upon induction was shown by increased specific activity of acetylcholinesterase (AChE). Incubation of MELCs with 5 mmol/L HMBA in RPMI supplemented with 1% fetal calf serum (FCS) (instead of the usual 5%), induced cells to selectively express high levels of AChE (up to approximately 170 mU/mg protein) with little activation of Hb synthesis (less than 5% B+ cells). The increase in AChE levels was a general phenomenon affecting the whole cell population and approached its maximum within 3 days of incubation with the inducer. Subsequently, MELCs become committed to terminal division, undergoing growth arrest and expression of the megakaryocytic phenotype even after the removal of HMBA. There were no appreciable changes of basal AChE levels in MELCs that were either made resistant to HMBA or treated with 0.1 mmol/L hemin that activated differentiated erythroid function without commitment. Phorbol 12-myristate 13-acetate (PMA), known to repress induced Hb synthesis in these cells, did not prevent the full increase in AChE when incubated with MELCs 2 days before HMBA addition. HMBA-induced MELCs always underwent AChE increase that was more or less pronounced depending on the low or high serum content in culture, respectively. Conversely, Hb expression was permitted only when MELCs were transferred in the late phase or at the end of commitment from low to high serum media. Variations of FCS content in culture media proved to be a simple and reliable approach to change the MELC response to inducers and to modulate expression of either megakaryocytic or mixed erythromegakaryocytic phenotype. These findings suggested that MELC might be considered, at least, as a bipotential model of differentiation to be used for studies on regulation of either megakaryocytic or erythroid markers and on competition between the two hematopoietic lineages. In this regard, it was intriguing that AChE levels attained under selective induction (low serum) were always higher than under conditions allowing coexpression of both AChE and Hb (high serum). Moreover, MELCs were also found to bind the specific rat-antimouse platelet monoclonal antibody 4A5.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetamides↗
PubMed1995

Induction, effects, and quantification of sublethal oxidative stress by hydrogen peroxide on cultured human fibroblasts.

Conditions to induce and parameters to evaluate sublethal oxidative stress of cultured human fibroblasts have been investigated in the attempt to identify markers for a more accurate quantification of cell injury. Sublethal oxidative stress was obtained by treating fibroblasts with 0.5 mM H2O2 in DMEM plus 5% FCS for times not exceeding 60 min. Under these conditions cells remained viable throughout long-term incubation, showing no appreciable release of cytosolic enzymes into the medium. On the contrary, exposures of fibroblasts to 0.5 mM H2O2 for times > 60 min induced a lethal cell injury which was fully expressed 2 days later by massive monolayer wasting and leakage of cytosolic components. Early metabolic effects of sublethal stress consisted of a rapid and significant fall of both ATP and NAD+ pools. Concomitantly, there was a moderate increase (about threefold) in both ADP-ribosyl transferase activity and free [Ca2+]i, while the specific activity of glyceraldehyde-3-phosphate dehydrogenase was partially decreased upon treatment. Oxidative injury also caused delayed effects consisting of a large depression of both protein and DNA synthesis. However, while the former was partially restored within 10 days of incubation, the latter remained severely impaired, as encountered in a growth-arrested population. Microfilaments of H2O2-treated cells appeared to be morphologically altered due to partial fragmentation of cytoskeleton actin which, however, was still maintained in the polymerized form as F-actin. Moreover, sublethally injured fibroblasts exhibited a reduced adhesiveness to plastic once they were detached and reseeded into new dishes. Relative adhesion efficiencies (number of adherent cells at 16 h as a percentage of seeded cells) were found to correlate inversely with times of exposure to H2O2. This finding allowed the identification of a biological parameter which showed itself to be very sensitive to oxidative stress and was also useful for developing an assay to grade sublethal injury to fibroblasts.

Actin Cytoskeleton↗
PubMed1995

Heterogeneous expression of transketolase in rat brain.

Transketolase (TK; EC 2.2.1.1) is a key pentose phosphate shunt enzyme that plays an important role in the production of reducing equivalents and pentose sugars. TK activity declines in the brains of patients with Alzheimer's disease or Wernicke-Korsakoff syndrome, as well as in thiamine-deficient rats. Understanding the role of TK in the pathophysiology of these neurodegenerative conditions requires knowledge of its regional, cellular, and subcellular distribution within the brain. The current study employed in situ hybridization and immunocytochemistry to examine the distribution of TK mRNA and its encoded protein in adult rat brain. TK mRNA and protein were widely distributed throughout the brain. However, they were enriched in selective perikarya in the piriform cortex, nucleus of the diagonal band, red nucleus, dorsal raphe, pontine nucleus, locus coeruleus, trapezoid, inferior olive, and several cranial nerve nuclei. Lower expression of TK mRNA and protein occurred in layer V of cortex, olfactory tubercle, ventral pallidum, medial septal nucleus, hippocampus, thalamic and hypothalamic nuclei, mammillary body, central gray, and the substantia nigra. TK immunoreactivity also occurred in the nuclei of ubiquitously distributed glial cells, as well as ependymal cells. The heterogeneous distribution of TK may reflect a variety of metabolic activities among different brain regions but does not provide a simple molecular explanation for selective cell death in either thiamine deficiency or other conditions where TK is reduced.

Animals↗
PubMed1995

Percutaneous balloon mitral valvuloplasty: early and late results according to surgical risk and echocardiographic score.

OBJECTIVE AND DESIGN: Early results, complications and follow-up of 70 patients undergoing percutaneous balloon mitral valvuloplasty (BMV) were retrospectively analyzed to establish whether an increased surgical risk or an unfavourable echocardiographic score influenced the results. PATIENTS: The patients were divided into two groups according to the presence (group A, n = 31) or absence (group B, n = 38) of high surgical risk factors. The patients were also divided into two other groups according to the presence (group C, n = 46) or absence (group D, n = 20) of favourable mitral valve anatomy. Group A (high surgical risk) included patients fulfilling at least one of the following criteria: 65 years of age or older; previous surgical commissurotomy; depressed left ventricular function; respiratory or hepatic insufficiency; or previous aortic valve replacement. Mitral valve anatomy was classified as 4 to 16, according to the echocardiographic score established by Abascal et al. Group C patients had echocardiographic score below 8 and group D had echocardiographic scores of 8 or greater. INTERVENTIONS: Mean mitral valve gradient (MVG) and area (MVA) were Doppler-estimated immediately before and 48 h after the BMV. MAIN RESULTS: There were no differences in the early results and complications between groups A and B (MVA 1.8 +/- 0.5 versus 1.9 +/- 0.4 cm2). Final MVA was significantly greater in group C than in group D (MVA 1.9 +/- 0.4 versus 1.6 +/- 0.4 cm2; P = 0.03). There was no difference in the incidence of complications. Over a follow-up period averaging 19.1 months (range 1 to 55), 90.7% of the patients were in New York Heart Association functional class I or II. Four patients had a mitral valve replacement, one had a surgical commissurotomy and one had a second BMV. Two unrelated deaths occurred. There were no differences in the characteristics of the study population and the incidence of events in the follow-up period between groups. CONCLUSIONS: The results and outcome of BMV were unrelated to the general surgical risk, suggesting that this procedure may be used with particular benefit in this group of patients. In contrast, mitral valve anatomy must be considered as an important determinant of the results.

Adult↗
PubMed1994

Characteristic transketolase alterations in dermal fibroblasts of Alzheimer patients are modulated by culture conditions.

Cultured Alzheimer fibroblasts were found to present peculiar alterations of transketolase (TK) ascribed to enhanced proteolytic activities in these cells and tentatively proposed as a marker of the disease. TK abnormalities, consisting of enzyme forms (alkaline bands) with unusually high alkaline pI, were investigated with respect to the mechanism of their generation and modulation by culture conditions. Alzheimer fibroblasts propagated at different pH, within a range of 7.3-7.8, exhibited TK abnormalities whose expression correlated directly with increases in medium pH values. Alterations were mostly evident in cells grown at 5% CO2 saturation in the atmosphere and with 3.7 g/liter NaHCO3 in the medium to yield an initial pH of about 7.75. Alkaline bands were not detected in either Alzheimer fibroblasts incubated at 10% CO2 or in control cells under any of the other conditions tested. Changes in initial medium pH also affected the morphology of fibroblasts, which shifted from a relatively large to an elongated shape as the medium pH decreased. The formation of alkaline bands was abolished by the addition of E-64, a known cysteine protease inhibitor, to cells just prior to extraction. On the contrary, Alzheimer fibroblasts cultured for 2 days in the presence of the inhibitor maintained the typically altered TK pattern. The establishment of conditions suitable for the expression of TK alterations in Alzheimer fibroblasts might be of help for diagnostic purposes and provide information on still elusive pathogenetic mechanisms of the disease.

Alzheimer Disease↗
PubMed1993

High dose L-carnitine improves immunologic and metabolic parameters in AIDS patients.

Several reports indicate that systemic carnitine deficiency could occur in acquired immunodeficiency disease syndrome (AIDS), and that primary and secondary carnitine deficiency leads to critical metabolic dysfunctions. L-carnitine supplementation to peripheral blood mononuclear cells (PBMCs) of AIDS patients resulted in significant enhancement of the phytohemagglutinin (PHA)-driven proliferative response. High dose L-carnitine administration (6 gr per day for two weeks) to AIDS patients treated with zidovudine also led to increased PBMCs proliferation and reduced blood levels of triglycerides. In addition, a reduction of beta 2-microglobulin serum levels as well as circulating tumor necrosis factor (TNF)-alpha, mostly in patients exhibiting highly elevated levels, were found at the end of the treatment period. Our data suggest that in vivo L-carnitine could prove useful in ameliorating both the immune response and lipid metabolism in patients with AIDS, irrespective of initial serum carnitines levels. The mechanism(s) accounting for the observed results are currently not clear. Further studies are needed to confirm the hypothesis that L-carnitine affects the expression of HIV-induced cytokine.

Acquired Immunodeficiency Syndrome↗
PubMed1993

[Postoperative intravenous analgesia].

The authors report the results of two clinical studies on postoperative pain relief with PCA. In the first clinical study 44 patients, undergoing gynecologic surgery, were assigned at random to two groups. The first was treated by PCA (infusor Baxter) with morphine i.v. (basal bolus 0.05 mg/kg, loading doses 1 mg every 6-15'), the second with 10 mg morphine i.m. at the end of surgery and then on demand with a lock-out of 6h at least. In the 2nd clinical study, 40 elder patients submitted to orthopedic surgery, were assigned at random to two groups treated with PCA (morphine i.v., basal bolus 0.07 mg/kg, bolus PCA 0.007 mg/kg lock-out 15') and with continuous infusion (i.c.) (basal bolus 0.07 mg/kg, i.c. 0.02 mg/kg/h). Our data were analyzed with Student's "t" unpaired test and showed lower doses of the drug in the groups PCA (1st study PCA 25.98 mg/48h, i.m. 45.45 mg/48h, 2nd study PCA 0.155 mg/kg/12h, i.c. 0.311 mg/kg/12h) and lower rate of side effects in the same groups. Side effects were well controlled using symptomatic drugs. We proposed to our patients, at the end of observation, a questionnaire about general conditions, sleep, pain evaluation using a descriptive scale and retrospective evaluation. Patients and nurses agree PCA. Nursing staff expressed a positive opinion and patients said they benefitted from PCA. As reported, PCA appears from our results, valid and safe in postoperative pain relief.

Adult↗
PubMed1992

Acetylcholinesterase in murine erythroleukemia (Friend) cells: evidence for megakaryocyte-like expression and potential growth-regulatory role of enzyme activity.

Features of true acetylcholinesterase (AChE) regulation during growth and differentiation of Friend murine erythroleukemia cells (MELC) have been investigated with respect to other erythroid and nonerythroid murine elements. Enzyme levels of uninduced MELC were in between the very low AChE contents of erythroid cells and the huge amounts of activity exhibited by megakaryocytes and platelets. After MELC commitment to terminal division, the enzyme-specific activity increased largely, approaching values that were much closer to those of thrombocytic than of normal erythroid elements. The bulk of AChE activity in MELC, megakaryocytes, and platelets was found to be located in the cytosol as a free-soluble form. Moreover, during incubation, MELC actively released large amounts of AChE into the medium, like it occurs in murine thrombocytes. Conversely, the enzyme of the erythroid elements was mainly associated with the membranes and was not released extracellularly. Experiments with inducers showed that changes in AChE-specific activity of MELC correlated directly with the arrest of cell proliferation rather than with the activation of differentiated erythroid functions. The inverse relationship existing between MELC growth rates and AChE levels was further supported by the relative enzyme activities of the slow- and fast-growing subclones. We conclude that uninduced MELC potentially share properties of both the erythroid and megakaryoblastic phenotype. The latter might be revealed by typical regulation of AChE activity according to a thrombocytic-like program activated upon MELC commitment to terminal division. Eventually, the inhibition of MELC growth by exogenous pure bovine AChE suggested that the secreted murine enzyme might serve as a potential negative signal of cellular replication.

Acetylcholinesterase↗
PubMed1992

Tumour necrosis factor (TNF-alpha) and neurological disorders in HIV infection.

Tumour necrosis factor (TNF-alpha) concentrations were determined in the CSF from 42 HIV-infected patients, with or without CNS involvement. In addition, 14 subjects with various neurological disorders but without HIV antibodies were included as controls. Raised CSF concentrations of TNF-alpha (greater than 40 ng/l) were detected both in patients with AIDS dementia complex (ADC) (6/9) and with CNS opportunistic infections (10/19) and, less commonly, in HIV infected subjects without CNS diseases (2/14) and in anti-HIV negative controls (1/14). The highest CSF concentrations of TNF-alpha (greater than 100 ng/l), however, were found in seven out of eight patients with cryptococcal meningitis. Although a role for TNF-alpha in demyelinating lesions associated with ADC has been suggested, our results indicate that a clear elevation of TNF-alpha in the CSF from HIV positive patients mostly occurs in acute inflammatory disorders, such as cryptococcal meningitis.

AIDS Dementia Complex↗
PubMed1992

Constitutive expression of a megakaryocytic functional property by murine erythroleukemia (Friend) cells: the incorporation of serotonin.

Murine Friend-derived erythroleukemia cells (MEL) are generally believed to be unipotential progenitors inducible to terminal erythroid differentiation. However, we found that MEL can constitutively incorporate significant amounts of radiolabeled serotonin ([3H]5-HT). Because this process is typical of cells belonging to the megakaryocytic lineage, we investigated the significance and mechanisms of 5-HT incorporation in the MEL system. We observed that: 1) normal murine erythroid cells and erythroid progenitors do not incorporate [3H]5-HT, as well as normal murine myeloid cells and the human myeloid cell line HL-60; on the other hand, the human erythroleukemia cell lines K562 and HEL, which have been shown to constitutively express megakaryocytic features, were able to incorporate [3H]5-HT; 2) MEL incorporated 5-HT by an active and saturable mechanism, dependent on temperature and sodium concentration in the medium; and 3) 5-HT uptake was very rapid. Moreover, because about 65% of cell-associated radioactivity was no longer displaced by the cold substrate, we assumed it to represent "true" cytoplasmic internalization. Finally, 5-HT incorporation by MEL was inhibited by clomipramine, ouabain, and reserpine, which are known inhibitors of 5-HT uptake in platelets. The commitment of MEL to terminal erythroid differentiation by hexamethylene bisacetamide or dimethyl sulfoxide greatly reduced the capacity to incorporate [3H]5-HT. These results seem to suggest that the MEL system, although mainly erythroid as regards its differentiation capability, constitutively expresses features of the megakaryocytic lineage, possibly disclosed by the ability to incorporate 5-HT. This hypothesis was further supported by the findings that 30%-40% of uninduced MEL were labeled by a polyclonal antibody raised against murine platelets that selectively recognized megakaryocytes in murine bone marrow smears.

Acetamides↗
PubMed1992

Acute respiratory effects of sublingual buprenorphine: comparison with intramuscular morphine.

In this randomized, double-blind, placebo study, the respiratory effects of a single dose of sublingual buprenorphine (0.4 mg) were examined and compared with those induced by one dose of intramuscular morphine (10 mg) in a population of women, aged 25-65 years, admitted at the Hospital for Elective Surgery because of uterine fibromyomatosis. Some indices of control of breathing (P0.1, VT/TI, VE, VA, TI, TE, TI/TTot, RR), gas exchange parameters (D[A-a]O2, VD/VT, PAO2) and blood gases (PaO2, PaCO2) were measured in basal condition and at 30, 60, 90, 180 and 360 min after the administration of the drugs. No significant changes of the respiratory function were observed in patients who have received sublingual buprenorphine. In the morphine-group, however, mild PaO2 decrease and PaCO2 increase were found at 60 and 90 min (p less than 0.05), without any reduction of the respiratory drive activity, as shown by P0.1, VT/TI and VE. The significant FRC reduction, observed in the morphine-group (p less than 0.05), could have induced both TE shortening and RR increase with larger dead space ventilation and consequent fall of VA (p less than 0.05). These results suggest that the administration of one dose of sublingual buprenorphine (0.4 mg) does not cause any detrimental respiratory effect; on the other hand, an appreciable, although clinically trivial, worsening of the respiratory function results from intramuscular morphine (10 mg), in the absence of any obvious respiratory depression.

Administration, Sublingual↗
PubMed1991

Enhanced proteolytic activities in cultured fibroblasts of Alzheimer patients are revealed by peculiar transketolase alterations.

Characteristic alterations of transketolase (TK) in extracts from cultured Alzheimer fibroblasts have previously been reported (Paoletti et al. (1990) Biochem. Biophys. Res. Commun., 172: 396-401). These abnormalities, encountered in 9 out of 13 Alzheimer patients, were revealed following isoelectric focusing and consisted of enzyme forms having unusually high alkaline pI values (alkaline bands). The present work has shown that immunologically detected alkaline bands were progressively expressed when Alzheimer fibroblasts were incubated for three weeks without medium changes. Full expression of the altered enzyme pattern was not linked to relative cell density in the petri dish; rather, it appeared to be dependent directly on the time elapsed since cell confluence was reached. Alkaline bands could artificially be induced also in both crude and pure TK preparations from normal cells by a treatment with commercial proteases, particularly chymotrypsin. Moreover, specific inhibitors of endogenous cysteine-proteases were capable of abolishing TK alkaline bands in Alzheimer fibroblasts thus turning a pathological into a normal enzyme pattern. Results obtained suggest that Alzheimer fibroblasts contain enhanced Ca(2+)-independent cysteine-proteolytic activities as compared to normal and other pathological cells. These enzymes, exhibiting chymotrypsin-like activity, might exert their degradative effects at the time of cell extraction using TK and probably other cell components as potential substrates. However, peculiar TK abnormalities represent so far an useful biochemical marker detectable in fibroblasts of living Alzheimer patients and closely associated to this neurological disorder.

Alzheimer Disease↗
PubMed1991

[Isolated persistent left superior vena cava. Detection of cause during central venous catheterization].

The Authors report the causal discovery of isolated persistent left superior vena cava (IPLSVC) during a central venous incannulation with a Groshong's catheter, in a patient undergoing bone marrow transplant. After a short introduction about the IPLSVC ontogenesis, they stress the need for fluoroscopy during the central venous incannulation. The Authors conclude that the possibility of angiocardiography has been very helpful, in this case, for diagnosis and prognosis.

Angiocardiography↗
PubMed1990

Occurrence of transketolase abnormalities in extracts of foreskin fibroblasts from patients with Alzheimer's disease.

Foreskin fibroblast cell lines from healthy subjects and patients with Alzheimer's disease or other neurological disorders have been analyzed for transketolase, by means of isoelectrofocusing and specific immunostaining. The enzyme profile in 70% of Alzheimer cell cultures exhibits alterations which are not encountered in controls and in other neurological diseases examined. Enzyme abnormalities most frequently observed were the appearance of new transketolase forms having unusually high alkaline pI. Experiments carried out with intact cells and with cell extracts treated with and without phenylmethyl-sulphonyl fluoride, suggest that the peculiar transketolase abnormalities observed in Alzheimer fibroblasts are due to enhanced proteolysis occurring in these cells rather than to intrinsic enzyme lability.

Alzheimer Disease↗