The growth-related gene product beta induces sphingomyelin hydrolysis and activation of c-Jun N-terminal kinase in rat cerebellar granule neurones

The growth-related gene product beta (GRObeta) is a small chemoattractant cytokine that belongs to the CXC chemokine family, and GRObeta receptors are expressed in the brain, including the cerebellum. We demonstrate that rat cerebellar granule neurones express the GRObeta receptor CXCR2. We also show that, in addition to the known stimulation of a phosphoinositide-specific phospholipase C, GRObeta activates both neutral (N-) and acidic (A-) sphingomyelinases (SMase) and the stress-activated c-Jun N-terminal kinase 1 (JNK1). Although both exogenous ceramide and bacterial SMase stimulate JNK1, GRObeta-induced JNK1 activation is an event probably independent of ceramide generated by A-SMase, since it is maintained in the presence of compounds that block A-SMase activity. This is the first report on the activation of the SMase pathway by chemokines.

CXC chemokines interleukin-8 (IL-8) and growth-related gene product alpha (GROalpha) modulate Purkinje neuron activity in mouse cerebellum

We give here evidence that Purkinje neurons (PNs) of mouse cerebellar slices studied with patch clamp technique combined with laser confocal microscopy, respond to human IL-8 and GROalpha by (i) a cytosolic Ca2+ transient compatible with inositol (1,4,5) trisphosphate (InsP3) formation; (ii) an enhancement of the neurotransmitter release; and (iii) an impairment of the long-term depression of synaptic strength (LTD). It was also found the expression of IL-8 receptor type 2 in PN and granule cells by immunofluorescence, immunoblotting and RT-PCR analysis. Considered together these findings suggest that IL-8 and GROalpha may play a neuromodulatory role on mouse cerebellum.

Modulation of the neurotransmitter release in rat cerebellar neurons by GRO beta

We report here that, in cultured cerebellar granule cells, the CXC chemokine GRObeta stimulates the signaling pathway of the extracellular signal-regulated kinases, and enhances both evoked and spontaneous postsynaptic currents in patch clamped Purkinje neurons from rat cerebellar slices. The GRObeta-induced enhancement of the excitatory post-synaptic currents evoked by stimulating the parallel fibres is blocked by the inhibitor of the extracellular signal-regulated kinases pathway PD98059, which also reduces both basal frequency of spontaneous post-synaptic currents and mean amplitude of evoked excitatory post-synaptic currents. Our results suggest that GRObeta modulates neurotransmitter release in the cerebellum through the activation of the extracellular signal-regulated kinases pathway.

Platelet activation and cytokine production during hypothermic cardiopulmonary bypass--a possible correlation?

Cardiopulmonary bypass (CPB) is associated with impaired platelet function and a systemic inflammatory response. The present study was designed to evaluate whether any correlation between platelet activation and inflammatory response during CPB exists. The results obtained from 8 patients undergoing hypothermic CPB for cardiac surgery showed the occurrence of a moderate degree of platelet activation during CPB, demonstrated by an increase of platelet CD62P expression in correlation with an increase of beta-thromboglobulin levels, with a concomitant decrease of in vitro platelet response. Plasma IL-1beta levels significantly increased during CPB, with a peak between 1 and 4 h after CPB. Similarly, IL-6 levels were elevated 30 min from CPB starting, peaked at 4 h, and remained elevated after 24 h. A direct correlation was found between plasma IL-1beta and IL-6 levels. A significant correlation between plasma IL-1beta and beta-thromboglobulin levels was also found. In turn, plasma beta-thromboglobulin levels correlated with CD62P expression on activated platelets. An inverse correlation was found between in vitro platelet aggregation and plasma IL-1beta or IL-6 levels. From the present results it may be speculated that platelet activation during CPB may contribute, through the release of IL-1beta, to activation of endothelial cells and subsequent release of other cytokines with chemotactic and pro-inflammatory properties, thus playing an important role in the inflammatory response associated with CPB.

Aluminum site structure in serum transferrin and lactoferrin revealed by synchrotron radiation X-ray spectroscopy

The Al site structure of serum transferrin and lactoferrin is investigated using X-ray absorption near edge structure (XANES) spectroscopy. Al K-edge spectra in the mono- and dialuminum forms of the proteins have been recorded for the first time. Our results show that the aluminium ion is hexa-coordinated in an octahedral-like symmetry and that the monoaluminum form, where only the C-terminal binding site is saturated, has an increased structural distortion around the metal site.

Spontaneous and repetitive calcium transients in C2C12 mouse myotubes during in vitro myogenesis

Fluorescence videomicroscopy was used to monitor changes in the cytosolic free Ca2+ concentration ([Ca2+]i) in the mouse muscle cell line C2Cl2 during in vitro myogenesis. Three different patterns of changes in [Ca2+]i were observed: (i) [Ca2+]i oscillations; (ii) faster Ca2+ events confined to subcellular regions (localized [Ca2+]i spikes) and (iii) [Ca2+]i spikes detectable in the entire myotube (global [Ca2+]i spikes). [Ca2+]i oscillations and localized [Ca2+]i spikes were detectable following the appearance of caffeine-sensitivity in differentiating C2Cl2 cells. Global [Ca2+]i spikes appeared later in the process of myogenesis in cells exhibiting coupling between voltage-operated Ca2+ channels and ryanodine receptors. In contrast to [Ca2+]i oscillations and localized [Ca2+]i spikes, the global events immediately stopped when cells were perfused either with a Ca2+-free solution, or a solution with TTX, TEA and verapamil. To explore further the mechanism of the global [Ca2+]i spikes, membrane currents and fluorescence signals were measured simultaneously. These experiments revealed that global [Ca2+]i spikes were correlated with an inward current. Moreover, while the depletion of the Ca2+ stores blocked [Ca2+]i oscillations and localized [Ca2+]i spikes, it only reduced the amplitude of global [Ca2+]i spikes. It is suggested that, during the earlier stages of the myogenesis, spontaneous and repetitive [Ca2+]i changes may be based on cytosolic oscillatory mechanisms. The coupling between voltage-operated Ca2+ channels and ryanodine receptors seems to be the prerequisite for the appearance of global [Ca2+]i spikes triggered by a membrane oscillatory mechanism, which characterizes the later phases of the myogenic process.

Geographical variation in water relations, hydraulic architecture and terpene composition of Aleppo pine seedlings from Italian provinces

Ecotypic variations in leaf conductance, soil-to-leaf hydraulic conductance, components of tissue water potential, hydraulic architecture parameters and xylem embolism were examined in greenhouse-grown two-year-old Aleppo pine (Pinus halepensis Mill.) seedlings from six origins representing the geographic range of the species in Italy. Cortical resin composition of the seedlings was also determined. Measurements were made on well-watered seedlings and on seedlings subjected to recurring severe drought. Drought-stressed seedlings had lower mean leaf conductances, transpiration rates and soil-to-leaf hydraulic conductances than well-watered seedlings. They also exhibited more negative osmotic potentials, higher relative water deficit at incipient plasmolysis, but a similar maximum modulus of elasticity. Drought-stressed seedlings showed a higher degree of xylem embolism, a lower Huber value, lower leaf specific conductivity and lower specific conductivity than well-watered seedlings. Drought-stressed seedlings of provenances from more xeric habitats (Tremiti, Porto Pino and Mottola) had greater leaf conductances, transpiration rates and soil-to-leaf hydraulic conductances than drought-stressed seedlings of provenances from more mesic habitats (Imperia, Otricoli and Vico del Gargano). They also showed higher osmotic adjustment and a lower degree of xylem embolism. Among provenances, there were no significant differences in hydraulic architecture parameters in response to the drought treatment; however, Tremiti and Porto Pino seedlings displayed smaller drought-induced reductions in specific conductivity and leaf specific conductivity, respectively, than seedlings from other provenances. These differences suggest that seedlings from xeric provenances, especially Tremiti, have greater resistance to desiccation than seedlings from mesic provenances. No clear association was found between terpene variability and the other traits investigated, although terpene composition was related to the geographical distribution of the provenances. We conclude that the drought-tolerance responses of Tremiti make it a more suitable provenance than the others for establishment on sites prone to severe soil water deficits.

Functional properties of neuronal nicotinic acetylcholine receptor channels expressed in transfected human cells

To study how subunit composition affects the functional properties of neuronal nicotinic acetylcholine receptors (nAChRs), we examined the behaviour of acetylcholine (ACh)-induced single-channel currents in human BOSC 23 cells transiently transfected with various subunit cDNA combinations. For all nAChRs examined (chick and rat alpha 3 beta 4, chick alpha 3 beta 2, alpha 4 beta 2, alpha 7 and alpha 8), expression levels were high enough to allow measurements of acetylcholine-evoked whole-cell currents and nicotine-elicited Ca2+ transients as well as the functional characterization of nAChR channels. Unitary acetylcholine-evoked events of alpha 8 nAChR had a slope conductance of 23 pS, whereas two conductance classes (19-23 and 32-45 pS) were identified for all other nAChR channels. The mean channel open times were significantly longer for homomeric alpha 7 and alpha 8 nAChRs (6-7 ms) than for heteromeric nAChRs (1-3 ms), with the exception of alpha 3 beta 4 nAChRs (8.4 ms for rat, 7 ms for chick). At least two species of heterologously expressed nAChRs (alpha 3 beta 4 and alpha 3 beta 2) exhibited single-channel characteristics similar to those reported for native receptors. The variety of nAChR channel conductance and kinetic properties encountered in human cells transfected with nAChR subunits contributes to the functional diversity of nAChRs in nerve cells.

[Analysis of risk factors in patients undergoing closed heart mitral commissurotomy]

The aim of this study was to analyse the risk factors in patients undergoing closed heart commissurotomy (CHC). From 1956 to 1978 a total of 630 patients with severe mitral stenosis underwent CHC at this Institute. The study was performed on a sample of 100 patients. Follow-up was performed using data taken from the Institute archives, questionnaires sent to the doctors in charge, telephone interviews or visits to outpatient clinics by the Institute's medical staff. The mortality rate 30 days after surgery was 2.9%. Re-CHC was necessary in 11 patients after a mean interval of 7.2 years. The overall probability of survival was 83%, 71%, 48% an 33% respectively at 10, 20, 30 and 40 years. Survival free from mitral re-operation at 10, 20, 30 and 40 years was 76%, 39%, 29% and 11% respectively. The probability of incidence for central and peripheral thromboembolism was 38%, 26%, 11% and 4% at 10, 20, 30 and 40 years. Mitral valve replacement surgery (MVR) was performed in a total of 64 patients. Operative mortality was 0.6% (1 patient). The mean duration of follow-up in patients undergoing post-CHC MVR was 10 years. The probability os survival in overall terms and free of cardiac decompensation was 79 and 53% respectively. From this study it is clear the CHC is a surgical procedure that offers excellent long-term results with a low incidence od thromboembolic events, very low costs and a good quality of life. CHC currently represents a valid alternative o mitral valve replacement in selected patients.

Acetylcholine-activated inward current induces cytosolic Ca2+ mobilization in mouse C2C12 myotubes

We examined the spatiotemporal pattern of intracellular Ca2+ liberation in mouse myotubes by means of fluorescence imaging of cytosolic free Ca2+ together with the simultaneous recording of membrane whole-cell currents. Acetylcholine (ACh) applications to C2C12 myotubes equilibrated in Ca(2+)-free medium and voltage clamped at -50 mV evoked localized fluorescence transients of variable amplitude with less than 0.5 s delay. Under the same experimental conditions, fluorescence transients were elicited by ACh also in mouse primary myotubes. Ca2+ transients were inhibited in myotubes clamped at depolarized potentials (-10 mV to +50 mV), or equilibrated in a Na+,Ca(2+)-free medium as well as in cells loaded with heparin, or with inositol (1,4,5) trisphosphate (InsP3). To investigate whether InsP3 could induce Ca2+ mobilization, [Ca2+]i determinations were carried out in myotubes loaded with InsP3 through the whole-cell patch-clamp recording pipette or by extracellular application in permeabilized cells. InsP3 diffusion into the myoplasm caused Ca2+ spikes with 5 +/- 1 s (mean +/- SEM) delay from the rupture of the membrane patch. Spikes were followed by sustained increases in fluorescence or by damped oscillations. In permeabilized myotubes, InsP3 induced the release of sequestered 45Ca2+ with a half-maximally effective concentration (EC50) of 0.28 +/- 0.05 microM, and Hill coefficient of 0.79 +/- 0.09. It is concluded that the ACh-activated inward current in mouse myotubes is coupled to cytosolic Ca2+ mobilization from internal InsP3-sensitive pools.

Cholinergic responses in cloned human TE671/RD tumour cells

The cholinergic responses of the human tumour cell line TE671/RD were examined using digital Ca2+ imaging fluorescence microscopy and patch-clamp measurements. In response to stimulation of the muscarinic acetylcholine (ACh) receptor (mAChR), the intracellular concentration of Ca2+ ([Ca2+]i) rose about two-fold, in parallel with inositol 1,4,5-trisphosphate accumulation, measured by chromatographic techniques. By contrast, there was no increment of [Ca2+]i upon stimulation of the nicotinic ACh receptor (nAChR), nor after caffeine application. Electrophysiological experiments showed that TE671/RD cells lack functional voltage-activated Ca2+ channels. The stimulation of the nAChR induced transient whole-cell currents (IACh). Little or no current was detected in isotonic extracellular Ca2+, with Cs+ in the patch pipette. Cell pretreatment with muscarine reduced IACh by about 20%, without consistent modifications of current kinetics. Muscarine applied to the extra-patch membrane under the cell-attached configuration had no obvious effect on ACh-evoked unitary events. In conclusion, in human TE671/RD cells, muscarinic stimulation increases [Ca2+]i, while nicotinic stimulation does not. In addition, the nAChR exhibits peculiar ion permeability properties and is not functionally regulated by the breakdown of phosphoinositides.

Activation of the nicotinic acetylcholine receptor mobilizes calcium from caffeine-insensitive stores in C2C12 mouse myotubes

In cultured mouse C2C12 myotubes, digital Ca2+ imaging fluorescence microscopy using the acetoxymethyl ester of Fura-2, Fura-2-AM, showed that, in the absence of extracellular Ca2+, acetylcholine (ACh) and nicotine, but not muscarine, raised the intracellular concentration of Ca2+ ([Ca2+]i) by about tenfold. ACh-induced Ca2+ mobilization was prevented by thapsigargin, a drug known to deplete inositol 1,4,5-trisphosphate (InsP3)-sensitive stores, and was concomitant with InsP3 accumulation. Caffeine, which releases Ca2+ from the ryanodine-sensitive stores of the sarcoplasmic reticulum, did not interfere with the ACh-induced [Ca2+]i increase. Ca2+ mobilization was also inhibited when myotubes were depolarized by high K+, or when extracellular Na+ was omitted. Nicotinic ACh receptor (nAChR) stimulation lowered intracellular pH with a time course slower than the [Ca2+]i increase. Possible mechanisms linking the current flowing through the nAChR pore to [Ca2+]i increase are discussed.

[Primary malignant lymphoma of the parotid gland. Report of a case]

Primary malignant lymphoma of the parotid gland is often correlated, in literature data, with inflammatory autoimmunological disease of the salivary gland. Finding of blasticlymphoid cells in myoepithelial scialoadenitic areas in a case of parotid disease is described by the Authors. Needle may be useful in detecting these high radio-chemosensitive neoplasms to reduce the occurrence of complications of total parotidectomy.

Acetylcholine induces voltage-independent increase of cytosolic calcium in mouse myotubes

Electrophysiological, biochemical, and Ca2+ imaging studies of cultured mouse myotubes were used to investigate whether the neurotransmitter acetylcholine causes an increase in intracellular Ca2+ concentration ([Ca2+]i) through activation of a second messenger system. Bath applications of acetylcholine to myotubes (i) elicited a significant membrane current even in a Na(+)-free Ca2+ medium, when the current was carried mainly by calcium ions; (ii) caused a rapid and transient cytosolic accumulation of inositol 1,4,5-trisphosphate; (iii) evoked a conspicuous alpha-bungarotoxin-sensitive long-lasting [Ca2+]i enhancement even in the presence of Cd2+; and (iv) transiently increased [Ca2+]i when cells were equilibrated in a Ca(2+)-free atropine-containing medium. We propose that, in addition to opening ion channels, the nicotinic action of acetylcholine on the muscle cell membrane increases [Ca2+]i through activation of the inositol 1,4,5-trisphosphate second messenger system and mobilization of Ca2+ from intracellular stores.

Interleukin-2 lengthens extrajunctional acetylcholine receptor channel open time in mammalian muscle cells

The effect of interleukin-2 (rIL-2) on nicotinic acetylcholine receptors (nAChR) was examined on cultured muscle fibres isolated from the flexor digitorum brevis muscle (FDB) of the rat and on aneural mouse cultured C2 myotubes. Intracellular measurement of the sensitivity to iontophoretically applied ACh demonstrated that the sensitivity of the extrajunctional nAChRs in cultured fibres showed a transient increase after application of rIL-2 (2,000-3,000 units/ml). Cell-attached patch-clamp experiments on the same fibres proved that rIL-2 (2,000 units/ml) induces a significant increase in the mean open time of the extrajunctional nAChR channel. The other channel parameters were not significantly modified. The same applied also to aneural mouse patch-clamped C2 myotubes exposed to rIL-2 (2,000 units/ml). In freshly dissociated fibres no effects on nAChR channels were observed following rIL-2 application. 125I-rIL-2 binding experiments on either 7-day cultured or freshly dissociated adult muscle fibres showed that a specific binding with a Kd of 2.07 +/- 0.4 nM develops in cultured fibres but fails to occur immediately after dissociation. It is concluded that rIL-2 modulates the duration of extrajunctional nAChR channels in both myotubes and adult muscle cells, and that this effect is probably due to the activation of a second messenger system.

Regulation of acetylcholine receptor desensitization in mouse myotubes by cytosolic cyclic AMP

Whole-cell currents activated by bath applications of acetylcholine (ACh) (10-30 microM) were recorded from patch-clamped myotubes of the mouse C2 cell line. Increasing concentrations of forskolin caused a dose-dependent fast decay of ACh-activated currents as compared to the long-lasting ACh-currents in control cells. The forskolin-induced modulation of nicotinic ACh receptor (nAChR) desensitization was proportional to the drug-induced elevation in the cyclic AMP (cAMP) cellular content. Furthermore, an increase in the rate of decay of the ACh-current response, which paralleled an elevation in cAMP cellular content, was caused by treatment with a calcitonin gene-related peptide (1 microM), 8-Br-cAMP (0.5 mM), or by loading the myotubes with cAMP. These results therefore indicate that the desensitization of nAChR is a cAMP-related process in C2-myotubes.

Influence of globin structure on the heme in dromedary carbonmonoxyhemoglobin

By use of X-ray absorption near-edge structure (XANES), circular dichroism, and visible absorption spectroscopies, dromedary carbonmonoxyhemoglobin has been characterized structurally and functionally. By consideration of the experimental results the following view emerges: (i) the quaternary structure is not the unique factor determining the tertiary environment around the heme, and (ii) the multiplicity of interactions between hemoglobin and solvent components induces a large number of globin conformations, which somehow affect the conformation of the heme such that the structural parameters (i.e., the doming of porphyrins, the movements of the iron relative to the heme plane, the distortion of the ligand field, and the change in the Fe-C-O angle) can be uncoupled.

Heterogeneity of the isolated subunits of the fetal and adult human hemoglobin in solution, detected by XANES spectroscopy

Differences in the local structure of the heme in the isolated alpha-, beta- and gamma-chains of the adult and fetal human hemoglobin are detected by XANES (X-ray absorption near-edge structure) spectroscopy. The ligand bonding angle to the iron ion in the ligated forms and the displacement of the Fe respect to the porphyrin plane in the deoxy forms are found to be different for each chain.

Oxygen bonding in human hemoglobin and its isolated subunits: a XANES study

The X-ray absorption near edge structure (XANES) spectra of the human adult and foetal hemoglobin, of the isolated alpha and beta chains, in the oxygenated forms, and of the oxymyoglobin and carp oxyhemoglobin have been measured at the wiggler beam line of the Frascati Synchrotron radiation facility. The bonding angle of oxygen molecule at the iron site in these hemoproteins in solution, has been measured using the multiple scattering theory for data analysis.

Local Fe site structure in the tense-to-relaxed transition in carp deoxyhemoglobin: a XANES (x-ray absorption near edge structure) study

The Fe-site structure variation in the transition from the low-affinity tense (T) quaternary structure to the high-affinity relaxed (R) structure in carp deoxyhemoglobin was studied by analysis of multiple scattering resonances in the XANES (x-ray absorption near edge structure) spectra. High signal-to-noise XANES spectra were measured at the Frascati "wiggler" synchrotron radiation facility. We find that the forces on the Fe active site due to the change of quaternary protein conformation do not induce variations greater than 0.01 A in interatomic Fe-N distances, variations greater than 0.1 A in the Fe displacement toward the heme plane, or the "doming" of the heme. The relevance of these results to the mechanism of protein control of ligand binding is discussed.

XANES of carboxy and cyanomet-myoglobin. The role of the distal histidine in the bent Fe-C-O configuration

The ligand bonding geometry of carboxy- and cyanomet-myoglobin (MbCO and MbCN) has been measured by the XANES method (X-ray Absorption Near Edge Structure). A comparison between the ligand bonding geometry of carboxy- and cyanomet-myoglobin and of chelated protoheme methyl ester shows that the bent Fe-C-O configuration is the same in both systems. Therefore, we suggest that this configuration is not associated with any steric constraint imposed by the side chains of the aminoacid residues at the distal side of the heme pocket.

Changes in Fe site structure from fetal to adult hemoglobin probed by XANES

Iron X-ray absorption near edge structure (XANES) spectra of human fetal (F) and adult (A) deoxyhemoglobin (deoxyHb) measured at the Frascati synchrotron radiation facility reveal the different geometrical structure of the Fe-porphyrin complexes in the two proteins. By this method, having determined for the first time the variation of atomic positions in fetal and adult hemoglobin in solution (close to the 'in vivo' situation), we give further insight into the structure-function relationship in hemoglobins.