Biomedical subjects

F Conti

Publications and source records attributed to F Conti.

At least 37 records · Page 2Linked to original sources

PubMed2002

Assessing the environmental impact of WWTP expansion: odour nuisance and its minimization.

As part of the effort to provide proper wastewater disposal for the City of Milan, the expansion of the WWTP located in Peschiera Borromeo has been planned and is currently under completion. The plant, sized for a population of less than 300,000, will soon treat the wastes from the south-east areas of Milan for a total capacity of over 500,000 p.e. The paper describes the approach to find a satisfactory solution of an alleged odour problem that is slowing down the completion of the plant restructuring. This included a survey of the existing plant and analysis of its final design, identification of odour emission sources and their quantification, and the examination of different alternatives for odour abatement. These were carried out using air quality modelling techniques consisting of dynamic, continuous "puff" models capable of reproducing diffusion even at very low pollutant concentrations. Several intervention hypotheses were tested and compared with the few existing regulatory norms and guidelines for odour pollution. In all but the minimum and the no-action hypotheses, proposed actions would results in a drastic reduction of nuisance effects at the receptors. Under the strongest intervention hypothesis (the one adopted by the WWTP agency), odour impact would be virtually eliminated.

Data Collection↗

PubMed2001

Skeletal muscle sodium channel is affected by an epileptogenic beta1 subunit mutation.

The syndrome of generalized epilepsy with febrile seizures plus type 1 (GEFS+) has been associated to the gene SCN1B coding for the sodium channel beta1 subunit (Wallace, R. H. et al. (1998) Nature Genetics 19, 366-370). In patients, a mutation of the cysteine 121 to trpyptophane (C121W) would cause a lack of modulatory activity of the beta1 subunit on sodium channels expressed in the brain, rendering neurons hyperexcitable. We have confirmed that the normal beta1-modulation of type-IIA adult brain alpha subunits (BIIA) expressed in frog oocytes is defective in C121W. We observed that the mixture of wild-type and mutant beta1 subunits is less effective than wild-type alone, suggesting that the mutant beta1 subunit does bind the alpha subunit. However, we also observed a similar lack of modulation by C121W of the in adult skeletal muscle alpha subunit (SkM1). This finding is in contrast with the simple idea that the mutational effect observed in the oocyte expression system is the principal physiopathological correlate of GEFS+, because no skeletal muscle symptoms have been reported in GEFS+ patients. We conclude that the manifestation of the pathological phenotype is conditioned by the presence of susceptibility genes and/or that the frog oocyte expression system is inadequate for the study of the mutant beta1 subunit physiopathology.

Animals↗

PubMed2001

Generating diversity at GABAergic synapses.

GABA-mediated transmission is characterized by high variability of synaptic responses. Major contributors to this variability are: presynaptic factors, including release probability and number of release sites; factors that determine synaptic GABA transients in the cleft, including diffusion and the actions of GABA transporters; and postsynaptic factors, including GABA(A) receptors subtypes, their location and number, their modulation by endogenous and exogenous factors, and their interactions with postsynaptic-anchoring proteins.

Animals↗

PubMed2001

The glial glutamate transporter GLT-1 is localized both in the vicinity of and at distance from axon terminals in the rat cerebral cortex.

Glutamate transporter-1 (GLT-1) is responsible for the largest proportion of glutamate transport in the brain and the density of GLT-1 molecules inserted in the plasma membrane is highest in regions of high demand. Previous electron microscopic studies in the hippocampus and cerebellum have shown that GLT-1 is concentrated both in the vicinity of and at considerable distance from the synaptic cleft [Chaudry et al., Neuron 15 (1995) 711-721], but little is known about its distribution in the neocortex. We therefore studied the spatial relationships between elements expressing the presynaptic marker synaptophysin and those containing GLT-1 in the rat cerebral cortex using confocal microscopy. Preliminary studies confirmed that GLT-1 positive puncta were exclusively astrocytic processes; moreover, they showed that in most cases GLT-1 positive processes either completely surrounded asymmetric synapses or had no apparent relationship with synapses; occasionally, they were apposed to terminals containing pleomorphic vesicles. In sections double-labeled for GLT-1 and synaptophysin, codistribution analysis revealed that 61.2% of pixels detecting fluorescent emission for GLT-1 immunoreactivity overlapped with pixels detecting synaptophysin. The percentages of GLT-1/synaptophysin codistribution were significantly different from controls. In sections double-labeled for GLT-1 and the vesicular GABA transporter, codistribution analysis revealed that 27% of pixels detecting GLT-1 overlapped with those revealing the vesicular GABA transporter.The remarkable 'synaptic' localization of GLT-1 provides anatomical support for the hypothesis that in the cerebral cortex GLT-1 contributes to shaping fast, point-to-point, excitatory synaptic transmission. Moreover, the considerable fraction of GLT-1 immunoreactivity localized at sites distant from axon terminals supports the notion that glutamate spillout occurs also in the intact brain and suggests that 'extrasynaptic' GLT-1 regulates the diffusion of glutamate escaped from the cleft.

Animals↗

PubMed2001

Serum tissue polypeptide specific antigen (TPS): a complementary tumor marker to CA 15-3 in the management of breast cancer.

The efficacy of CEA and CA15-3 tumor markers in monitoring breast cancer was evaluated in 1365 patients with either benign (n = 534) or malignant (n = 831) breast diseases. Thirty-nine breast cancer patients were monitored before and after neoadjuvant chemotherapy. Three hundred forty-nine patients were monitored during post-surgical follow-up for either a minimum of 5 years or until time of recurrence. Twenty-one patients with metastases were also monitored during chemotherapy. Elevated CA 15-3 and TPS levels were found in 28.6% and 30.0% of patients. CA 15-3 and TPS sensitivities rose to 71.9% and 66.3% in metastatic patients, respectively. The addition of TPS to CA 15-3 increased the sensitivity up to 44.4% in the overall population, and to 87.6% in patients with metastases. During post-surgical follow-up CA 15-3 was elevated in 65.7% and TPS in 61.3% of patients with recurrence. The combination of TPS and CA 15-3 increased the overall sensitivity by 12.7%. Longitudinal monitoring of metastatic patients undergoing chemotherapy demonstrated that, when positive, both CA 15-3 and TPS paralleled response to treatment. TPS monitoring may provide additional value when used in combination with CA15-3 during post-surgical follow-up of breast cancer patients.

Adolescent↗

PubMed2001

Claude Bernard: primer of the second biomedical revolution.

Claude Bernard, the son of a Beaujolais winegrower, moved to Paris to pursue his literary ambitions and went on to become one of the fathers of modern life sciences. What did Bernard do to earn universal renown? And are his teachings relevant to modern science?

Animal Welfare↗

PubMed2001

The expression of glutamate transporter GLT-1 in the rat cerebral cortex is down-regulated by the antipsychotic drug clozapine.

We show here that clozapine, a beneficial antipsychotic, down-regulates the expression of the glutamate transporter GLT-1 in the rat cerebral cortex, thereby reducing glutamate transport and raising extracellular glutamate levels. Clozapine treatment (25--35 mg kg(-1) day(-1) orally) reduced GLT-1 immunoreactivity in several brain regions after 3 weeks; this effect was most prominent after 9 weeks and most evident in the frontal cortex. GLT-1 protein levels were reduced in the cerebral cortex of treated rats compared with controls and were more severely affected in the anterior (71.9 +/- 4.5%) than in the posterior (53.2 +/- 15.4%) cortex. L-[(3)H]-glutamate uptake in Xenopus laevis oocytes injected with mRNA extracted from the anterior cerebral cortex of rats treated for 9 weeks was remarkably reduced (to 30.6 +/- 8.6%) as compared to controls. In addition, electrophysiological recordings from oocytes following application of glutamate revealed a strong reduction in glutamate uptake currents (46.3 +/- 10.2%) as compared to controls. Finally, clozapine treatment led to increases in both the mean basal (8.1 +/- 0.7 microM) and the KCl-evoked (28.7 +/- 7.7 microM) output of glutamate that were 3.1 and 3.5, respectively, higher than in control rats. These findings indicate that clozapine may potentiate glutamatergic synaptic transmission by regulating glutamate transport.

ATP-Binding Cassette Transporters↗

PubMed2001

Effects of bile salts and aliphatic ionic surfactants on human lymphocyte proliferation.

BACKGROUND: The molecular mechanisms involved in the immunosuppressive properties of bile salts are partly unknown. METHODS: The aim of the study was to compare the effects of bile salts to those of various compounds with a steroid structure, or straight-chain hydrocarbons of different lengths and polar groups in the human mixed lymphocyte reaction. RESULTS: We showed a significant correlation between the effects of bile salts and a low critical micellar concentration, a high surface activity index, and the absence of conjugation. In addition to mixed lymphocyte reaction (MLR) inhibition, chenodeoxycholate (CDC) inhibit ConA-induced IL2 production without any effect on IL2 R expression. Fusidate, a negatively charged steroid, with physical properties comparable to those of deoxycholate, had similar effects. Cetyltrimethylammonium bromide (CTAB), which exhibited a very low critical micellar concentration, inhibited mixed lymphocyte reaction in an extent comparable to cyclosporin A. In contrast, aliphatic compounds with critical micellar concentrations in the same range as bile salts but with a lower molecular area had no effect. CONCLUSIONS: Amphiphilic negatively charged molecules inhibit T-cell proliferation to an extent that is dependent upon their hydrophobicity. These results may be explained, at least in part, by a modification in the cell membrane lipid bilayer structure.

Bile Acids and Salts↗

PubMed2001

Mechanism of block of single protopores of the Torpedo chloride channel ClC-0 by 2-(p-chlorophenoxy)butyric acid (CPB).

We investigated in detail the mechanism of inhibition by the S(-) enantiomer of 2-(p-chlorophenoxy)butyric acid (CPB) of the Torpedo Cl(-)channel, ClC-0. The substance has been previously shown to inhibit the homologous skeletal muscle channel, CLC-1. ClC-0 is a homodimer with probably two independently gated protopores that are conductive only if an additional common gate is open. As a simplification, we used a mutant of ClC-0 (C212S) that has the common gate "locked open" (Lin, Y.W., C.W. Lin, and T.Y. Chen. 1999. J. Gen. Physiol. 114:1-12). CPB inhibits C212S currents only when applied to the cytoplasmic side, and single-channel recordings at voltages (V) between -120 and -80 mV demonstrate that it acts independently on individual protopores by introducing a long-lived nonconductive state with no effect on the conductance and little effect on the lifetime of the open state. Steady-state macroscopic currents at -140 mV are half-inhibited by approximately 0.5 mM CPB, but the inhibition decreases with V and vanishes for V > or = 40 mV. Relaxations of CPB inhibition after voltage steps are seen in the current responses as an additional exponential component that is much slower than the gating of drug-free protopores. For V = 60 mV) with an IC50 of approximately 30-40 mM. Altogether, these findings support a model for the mechanism of CPB inhibition in which the drug competes with Cl(-) for binding to a site of the pore where it blocks permeation. CPB binds preferentially to closed channels, and thereby also strongly alters the gating of the single protopore. Since the affinity of CPB for open WT pores is extremely low, we cannot decide in this case if it acts also as an open pore blocker. However, the experiments with the mutant K519E strongly support this interpretation. CPB block may become a useful tool to study the pore of ClC channels. As a first application, our results provide additional evidence for a double-barreled structure of ClC-0 and ClC-1.

Animals↗

PubMed2001

Docetaxel in patients with anthracycline-resistant advanced breast cancer.

OBJECTIVE: To better determine docetaxel activity in patients with well-defined anthracycline-resistant breast cancer. METHODS: From October 1996, we carried out a phase II trial in 69 heavily pretreated patients with advanced breast cancer with docetaxel 100 mg/m(2) by a 1-hour infusion on day 1, with cycles repeated every 3 weeks. Patients were classified as having primary anthracycline resistance (n = 32), secondary anthracycline resistance (n = 7), anthracycline pretreatment (n = 22) or no anthracycline pretreatment (n = 8). RESULTS: Among 68 evaluable patients, we observed 6 (9%) complete responses and 27 (40%) partial responses, for an overall response rate of 49% (95% confidence interval 37-61%); the disease remained stable in 17 patients (25%). Responses according to the above subgroups were as follows: primary anthracycline resistance 41%, secondary anthracycline resistance 43%, anthracycline pretreatment 64% and no anthracycline pretreatment 43%. The median time to response, median time to progression and median overall survival were 2, 7 and 10 months, respectively. Myelosuppression was the dose-limiting toxicity, with grade 4 neutropenia occurring in 47% of the patients and neutropenic fever in 12%. G-CSF was added in the case of grade 4 febrile neutropenia; a 25% reduction in the dose of docetaxel was required in 4 patients. Other side effects were mild. CONCLUSIONS: The results of the present trial confirm the high activity of docetaxel in heavily pretreated patients with advanced breast cancer, including those with strictly defined anthracycline resistance.

Adult↗

PubMed2001

Increased cell surface expression of histocompatibility class II I-A(d) in c-fos transfected clones of the P388D1 murine macrophage cell line.

Numerous biological functions of the monocyte-macrophage lineage are affected by the presence of immunomodulators. Enhancement in transcription of c-fos has been shown in the murine P388D1 macrophage line treated by LPS, TPA, Ca++ ionophore or dibutyryl cAMP. In order to study the effects of an increased c-Fos protein level on macrophage functions, we previously have established stable c-fos-overexpressing clones in the P388D1 cell line. Here we report that the expression of class II MHC antigens (I-A(d) antigen) is increased in these clones, particularly after IFN-gamma treatment. No variation in the cell surface expression of IFN-gamma receptor was observed. The increase of I-A(d) cell surface expression was well correlated with the level of I-A(d) mRNA. No inducible NO synthase activity and no increase of TNF-alpha release were observed in c-fos transfected cells. A slight increase of the basal expression of the main class II MHC transcription factor CIITA which is further amplified by IFN-gamma treatment, was observed in the c-Fos overexpressing clones. This suggests that the increased I-A(d) expression in clones could result from a transactivating action of the c-Fos protein on the CIITA factor.

Animals↗

PubMed2000

Functional properties of sodium channels do not depend on the cytoskeleton integrity.

Several observations suggest an interaction of the sodium channel alpha-subunit with the cytoskeletal structures. However, there is a wide variability in the results of experiments of heterologous expression in Xenopus oocytes and studies on mammalian cells are sometimes contradictory. In general, there has been no direct demonstration that ad hoc large perturbations of the cytoskeleton modify the intrinsic properties of the sodium channels expressed endogenously or heterologously in plasma membranes. We have studied in CHO cells transfected with the rat muscle sodium channel alpha-subunit the effects of two substances expected to produce drastic perturbations of the cytoskeletal structure: Cytochalasin-D, which depolymerizes microfilaments, and Colchicine, which inhibits the microtubules polymerization. We observed no significant differences in the voltage dependence, kinetic parameters and surface density of the expressed sodium channels after treatment of the cells with these substances. We conclude that the two known main components of the cytoskeleton do not interfere directly with the sodium channel function or with the heterologous expression of channels in the cell membrane.

Animals↗

PubMed2000

Functional properties of sodium channels do not depend on the cytoskeleton integrity.

Actin Cytoskeleton↗

PubMed2000

Deficiency of the Fas apoptosis pathway without Fas gene mutations is a familial trait predisposing to development of autoimmune diseases and cancer.

Fas/Apo-1 (CD95) triggers programmed cell death (PCD) and is involved in immune response control and cell-mediated cytotoxicity. In the autoimmune/lymphoproliferative syndrome (ALPS), inherited loss-of-function mutations of the Fas gene cause nonmalignant lymphoproliferation and autoimmunity. We have recently identified an ALPS-like clinical pattern (named autoimmune lymphoproliferative disease [ALD]) in patients with decreased Fas function, but no Fas gene mutation. They also displayed decreased PCD response to ceramide, triggering a death pathway partially overlapping that used by Fas, which suggests that ALD is caused by downstream alterations of the Fas signaling pathway. Decreased Fas function is also involved in tumor development, because somatic mutations hitting the Fas system may protect neoplastic cells from immune surveillance. This work assessed the inherited component of the ALD defect by evaluating Fas- and ceramide-induced T-cell death in both parents and 4 close relatives of 10 unrelated patients with ALD. Most of them (22 of 24) displayed defective Fas- or ceramide-induced (or both) cell death. Moreover, analysis of the family histories showed that frequencies of autoimmunity and cancer were significantly increased in the paternal and maternal line, respectively. Defective Fas- or ceramide-induced T-cell death was also detected in 9 of 17 autoimmune patients from 7 families displaying more than a single case of autoimmunity within first- or second-degree relatives (multiple autoimmune syndrome [MAS] patients). Autoimmune diseases displayed by ALD and MAS families included several organ-specific and systemic forms. These data suggest that ALD is due to accumulation of several defects in the same subject and that these defects predispose to development of cancer or autoimmune diseases other than ALPS/ALD.

Adolescent↗

PubMed2000

Endogenous expression of the beta1A sodium channel subunit in HEK-293 cells.

The expression of the sole alpha-subunit of muscle or brain sodium channels in frog oocytes mediates currents with a bimodal inactivation with an abnormal slow mode that is strongly depressed only by co-expression of the beta1-subunit. In contrast, in the expression of the alpha-subunit in the human embryonic kidney cell line, HEK-293, the slow mode is almost absent, suggesting an endogenous expression of the beta1-subunit. We have tested this hypothesis by reverse transcriptase-polymerase chain reaction. We found an abundant expression of mRNA encoding the beta1A splicing of the putative regulatory sodium channel subunit but no mRNA encoding the beta1-subunit in HEK cells. This finding is consistent with the idea that the endogenous beta1A-subunit is sufficient for suppressing the slowly inactivating mode of sodium currents by co-assembly with alpha-subunits, and calls attention to the reliability of effects attributed in HEK cells to alpha-beta1 co-expression.

Animals↗

PubMed2000

Cardiac involvement in patients with Wegener's granulomatosis.

Wegener's granulomatosis (WG) is a systemic necrotizing vasculitis, which could potentially affect any organ system. However, there have only been a few reports on cardiac involvement. We described the echocardiographic findings in nine patients affected by WG. A complete M-mode, two-dimensional, Doppler and color-Doppler transthoracic echocardiogram was performed in nine patients (seven females and two males) affected by WG. In each patient, cardiac abnormality, for example, valvular damage, left ventricular global systolic dysfunction, or pericardial effusion, was detected. In particular, heart valve disease was found in eight patients, and in three cases, aortic valve insufficiency, which was severe enough to require surgical valve replacement, was observed. Cardiac involvement in patients with WG is common. In particular, there is a high frequency of aortic valve abnormalities. Thus, an echocardiographic study should be routinely performed.

Aged↗

PubMed2000

Defective interleukin-1 receptor antagonist production is associated with resistance of acute liver graft rejection to steroid therapy.

Thirty percent of acute liver graft rejection episodes are resistant to steroids. As interleukin-1 (IL-1) is an important target of steroid therapy, we examined the possible involvement of reduced sensitivity of IL-1 production to steroids or defective production of its antagonist, IL-1Ra. Patients were assessed during steroid-sensitive or -resistant rejection and 2 years later. In situ IL-1beta and IL-1Ra expression was evaluated by immunohistochemistry; their production was assayed by enzyme-linked immunosorbent assay and the gene polymorphisms by reverse transcriptase-polymerase chain reaction on blood cells. Hepatic IL-1beta and IL-1Ra expression were enhanced during rejection. IL-1 production and its inhibition by steroids were similar in steroid-responsive and steroid-resistant rejection. However, IL-1Ra production was lower in steroid-resistant than in steroid-responsive rejection, and this difference was still observed 2 years after rejection. IL-1beta and IL-1Ra gene polymorphisms did not differ between patients with and without steroid resistance. Low IL-1Ra production is associated with steroid resistance of acute rejection and is due to a constitutional defect. The early identification of such patients might qualify them for stronger anti-rejection therapy, including IL-1Ra.

Acute Disease↗

PubMed2000

Gating and flickery block differentially affected by rubidium in homomeric KCNQ1 and heteromeric KCNQ1/KCNE1 potassium channels.

The voltage-gated potassium channel KCNQ1 associates with the small KCNE1 subunit to form the cardiac IKs delayed rectifier potassium current and mutations in both genes can lead to the long QT syndrome. KCNQ1 can form functional homotetrameric channels, however with drastically different biophysical properties compared to heteromeric KCNQ1/KCNE1 channels. We analyzed gating and conductance of these channels expressed in Xenopus oocytes using the two-electrode voltage-clamp and the patch-clamp technique and high extracellular potassium (K) and rubidium (Rb) solutions. Inward tail currents of homomeric KCNQ1 channels are increased about threefold upon substitution of 100 mM potassium with 100 mM rubidium despite a smaller rubidium permeability, suggesting an effect of rubidium on gating. However, the kinetics of tail currents and the steady-state activation curve are only slightly changed in rubidium. Single-channel amplitude at negative voltages was estimated by nonstationary noise analysis, and it was found that rubidium has only a small effect on homomeric channels (1.2-fold increase) when measured at a 5-kHz bandwidth. The apparent single-channel conductance was decreased after filtering the data at lower cutoff frequencies indicative of a relatively fast "flickery/block" process. The relative conductance in rubidium compared to potassium increased at lower cutoff frequencies (about twofold at 10 Hz), suggesting that the main effect of rubidium is to decrease the probability of channel blockage leading to an increase of inward currents without large changes in gating properties. Macroscopic inward tail currents of heteromeric KCNQ1/KCNE1 channels in rubidium are reduced by about twofold and show a pronounced sigmoidal time course that develops with a delay similar to the inactivation process of homomeric KCNQ1, and is indicative of the presence of several open states. The single channel amplitude of heteromers is about twofold smaller in rubidium than in potassium at a bandwidth of 5 kHz. Filtering at lower cutoff frequencies reduces the apparent single-channel conductance, the ratio of the conductance in rubidium versus potassium is, however, independent of the cutoff frequency. Our results suggest the presence of a relatively rapid process (flicker) that can occur almost independently of the gating state. Occupancy by rubidium at negative voltages favors the flicker-open state and slows the flickering rate in homomeric channels, whereas rubidium does not affect the flickering in heteromeric channels. The effects of KCNE1 on the conduction properties are consistent with an interaction of KCNE1 in the outer vestibule of the channel.

Animals↗