New Insights into Dose-Dependent Effects of Curcumin on ARPE-19 Cells

Opposing dose-dependent effects of curcumin (Cur) have been documented in Retinal Pigment Epithelium (RPE); therefore, to shed the light on the mechanisms of action is crucial for ophthalmic applications. On this basis we explored new insights about the dose-dependent mechanisms triggered by Cur in human retinal pigment epithelial cells (ARPE-19). Three concentrations (0.01 mM; 0.05 mM; 0.1 mM) of Cur were tested, followed by morphological, molecular, and functional analysis of the cells. Cur 0.01 mM promotes a significant increase in cell proliferation, not affecting cell cycle progression and apoptosis; by contrast, Cur 0.05 mM and 0.1 mM block cellular proliferation and trigger S-phase cell cycle arrest without inducing apoptosis. The observation of neuronal-like morphological changes in Cur 0.05 mM and 0.1 mM were not associated with neuronal differentiation, as observed by the quantification of Neurofilament-200 and by the analysis of voltage-dependent currents by patch clamp. Evaluation of autophagic markers LC3BII and p62 revealed significant modulations, suggesting an important activation of autophagy in ARPE-19 cells treated with Cur 0.05 mM and Cur 0.1 mM; conversely, Cur 0.01 mM did not affect autophagy. Altogether, our findings show new dose-dependent mechanisms of action of Cur that suggest a wide therapeutic application in ocular diseases with different pathogenesis (i.e., proliferative vitreoretinopathy or Age-Related Macular Degeneration).

Neuromuscular Strategies in Stretch-Shortening Exercises with Increasing Drop Heights: The Role of Muscle Coactivation in Leg Stiffness and Power Propulsion

When applying drop jump exercises, knowing the magnitude of the stimulus is fundamental to stabilize the leg joints and to generate movements with the highest power. The effects of different drop heights on leg muscles coactivation, leg stiffness and power propulsion were investigated in fifteen sport science students. Drop jumps from heights of 20, 30, 40, 50, and 60 cm in a random order were performed on a force platform. During each drop jump, the ground reaction force, knee angle displacement, and synchronized surface-electromyography root-mean-square (sEMG_RMS) activity (vastus lateralis, VL; vastus medialis, VM; rectus femoris, RF; biceps femoris, BF; tibialis anterior, TA and lateral gastrocnemius, LG) were recorded. The coactivation in the pre-contact phase, between VL and BF, VM and BF as well as RF and BF, was dependent on the drop height (p < 0.01; effect size (ES) ranged from 0.45 to 0.90). Leg stiffness was dependent on the drop height (p < 0.001; ES = 0.27-0.28) and was modulated by the coactivation of VM-BF (p = 0.034) and RF-BF (p = 0.046) during the braking phase. Power propulsion was also dependent on the drop height (p < 0.001; ES = 0.34); however, it was primarily modulated by the coactivation of LG-TA during the braking phase (p = 0.002). The coactivation of thigh muscles explains leg stiffness adjustments at different drop heights. On the contrary, the coactivation of shank muscles is mostly responsible for the power propulsion.

Toward stomatal-flux based forest protection against ozone: The MOTTLES approach

European standards for the protection of forests from ozone (O₃) are based on atmospheric exposure (AOT40) that is not always representative of O₃ effects since it is not a proxy of gas uptake through stomata (stomatal flux). MOTTLES "MOnitoring ozone injury for seTTing new critical LEvelS" is a LIFE project aimed at establishing a permanent network of forest sites based on active O₃ monitoring at remote areas at high and medium risk of O₃ injury, in order to define new standards based on stomatal flux, i.e. POD_Y (Phytotoxic Ozone Dose above a threshold Y of uptake). Based on the first year of data collected at MOTTLES sites, we describe the MOTTLES monitoring station, together with protocols and metric calculation methods. AOT40 and POD_Y, computed with different methods, are then compared and correlated with forest-health indicators (radial growth, crown defoliation, visible foliar O₃ injury). For the year 2017, the average AOT40 calculated according to the European Directive was even 5 times (on average 1.7 times) the European legislative standard for the protection of forests. When the metrics were calculated according to the European protocols (EU Directive 2008/50/EC or Modelling and Mapping Manual LTRAP Convention), the values were well correlated to those obtained on the basis of the real duration of the growing season (i.e. MOTTLES method) and were thus representative of the actual exposure/flux. AOT40 showed opposite direction relative to PODY. Visible foliar O₃ injury appeared as the best forest-health indicator for O₃ under field conditions and was more frequently detected at forest edge than inside the forest. The present work may help the set-up of further long-term forest monitoring sites dedicated to O₃ assessment in forests, especially because flux-based assessments are recommended as part of monitoring air pollution impacts on ecosystems in the revised EU National Emissions Ceilings Directive.

Erythropoietin Increases GABAA Currents in Human Cortex from TLE Patients

Erythropoietin (EPO) is a hematopoietic growth factor that has an important role in the erythropoiesis. EPO and its receptor (EPO-R) are expressed all over in the mammalian brain. Furthermore, it has been reported that EPO may exert neuroprotective effect in animal models of brain disorders as ischemia and epilepsy. Here, we investigate whether EPO could modulate the GABA-evoked currents (I_GABA) in both human epileptic and non-epileptic control brain tissues. Therefore, we transplanted in Xenopus oocytes cell membranes obtained from autoptic and surgical brain tissues (cortex) of seven temporal lope epilepsy (TLE) patients and of five control patients. Two microelectrodes voltage-clamp technique has been used to record I_GABA. Moreover, qRT-PCR assay was performed in the same human tissues to quantify the relative gene expression levels of EPO/EPO-R. To further confirm experiments in oocytes, we performed additional experiments using patch-clamp recording in slices obtained from rat cerebellum. We show that exposure to EPO significantly increased the amplitude of the I_GABA in all the patients analyzed. No differences in the expression of EPO and EPO-R in both TLE and control patients have been found. Notably, the increase of I_GABA has been recorded also in rat cerebellar slices. Our findings show a new modulatory action of EPO on GABA_A receptors (GABA_A-Rs). This effect could be relevant to balance the GABAergic dysfunction in human TLE. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.

Interferon-free therapy in hepatitis C virus mixed cryoglobulinaemia: a prospective, controlled, clinical and quality of life analysis

BACKGROUND

Cryoglobulinaemic vasculitis (CV) is a lymphoproliferative disorder related to hepatitis C virus (HCV) infection; anti-viral therapy is the first therapeutic option. CV can be incapacitating, compromising the patients' quality of life (QoL). In a controlled study, interferon-based therapy was associated with a lower virological response in vasculitic patients than in patients without vasculitis. Limited, uncontrolled data on direct-acting anti-virals are available.

AIM

To evaluate safety, clinical efficacy, virological response and the impact of interferon-free treatment on QoL in HCV patients with and without mixed cryoglobulinaemia (MC).

METHODS

We prospectively studied HCV patients with cryoglobulinaemia (with vasculitis-CV- and without vasculitis-MC-) and without cryoglobulinaemia (controls), treated with direct-acting anti-virals. Hepato-virological parameters, CV clinical response and impact on QoL were assessed.

RESULTS

One hundred and eighty-two HCV patients were recruited (85 with CV, 54 with MC and 43 controls). A sustained virological response at 12 weeks (SVR12) was achieved in 166 (91.2%) patients (77/85 CV, 48/54 MC, 41/43 controls). In CV SVR patients, cryocrit levels progressively decreased and clinical response progressively improved, reaching 96.7%, 24 weeks after treatment. QoL, baseline physical and mental component summaries were lower in the CV group compared to the other groups (P < 0.05). Scores improved in all groups, and significantly in CV patients after SVR.

CONCLUSIONS

No significant differences in SVR rates were recorded between cryoglobulinaemic patients and controls and a high clinical and immunological efficacy was confirmed in CV, supporting the role of interferon-free therapy as the first therapeutic option. Interestingly, CV patients had worse baseline QoL than other HCV-positive groups and interferon-free therapy was effective in significantly increasing QoL, suggesting the important role of direct-acting anti-viral-based therapy in improving CV's individual and social burden.

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 β-thromboglobulin levels, with a concomitant decrease of in vitro platelet response. Plasma IL-1β 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-1β and IL-6 levels. A significant correlation between plasma IL-1β and β-thromboglobulin levels was also found. In turn, plasma β-thromboglobulin levels correlated with CD62P expression on activated platelets. An inverse correlation was found between in vitro platelet aggregation and plasma IL-1β or IL-6 levels. From the present results it may be speculated that platelet activation during CPB may contribute, through the release of IL-1β, 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.

Effects of long-term ambient ozone exposure on biomass and wood traits in poplar treated with ethylenediurea (EDU)

This is the longest continuous experiment where ethylenediurea (EDU) was used to protect plants from ozone (O3). Effects of long-term ambient O3 exposure (23 ppm h AOT40) on biomass of an O3 sensitive poplar clone (Oxford) were examined after six years from in-ground planting. Trees were irrigated with either water or 450 ppm EDU. Above (-51%) and below-ground biomass (-47%) was reduced by O3 although the effect was significant only for stem and coarse roots. Ambient O3 decreased diameter of the lower stem, and increased moisture content along the stem of not-protected plants (+16%). No other change in the physical wood structure was observed. A comparison with a previous assessment in the same experiment suggested that O3 effects on biomass partitioning to above-ground organs depend on the tree ontogenetic stage. The root/shoot ratios did not change, suggesting that previous short-term observations of reduced allocation to tree roots may be overestimated.

Hormonal and neuromuscular responses to mechanical vibration applied to upper extremity muscles

Objective

To investigate the acute residual hormonal and neuromuscular responses exhibited following a single session of mechanical vibration applied to the upper extremities among different acceleration loads.

Methods

Thirty male students were randomly assigned to a high vibration group (HVG), a low vibration group (LVG), or a control group (CG). A randomized double-blind, controlled-parallel study design was employed. The measurements and interventions were performed at the Laboratory of Biomechanics of the University of L'Aquila. The HVG and LVG participants were exposed to a series of 20 trials ×10 s of synchronous whole-body vibration (WBV) with a 10-s pause between each trial and a 4-min pause after the first 10 trials. The CG participants assumed an isometric push-up position without WBV. The outcome measures were growth hormone (GH), testosterone, maximal voluntary isometric contraction during bench-press, maximal voluntary isometric contraction during handgrip, and electromyography root-mean-square (EMG_rms) muscle activity (pectoralis major [PM], triceps brachii [TB], anterior deltoid [DE], and flexor carpi radialis [FCR]).

Results

The GH increased significantly over time only in the HVG (P = 0.003). Additionally, the testosterone levels changed significantly over time in the LVG (P = 0.011) and the HVG (P = 0.001). MVC during bench press decreased significantly in the LVG (P = 0.001) and the HVG (P = 0.002). In the HVG, the EMG_rms decreased significantly in the TB (P = 0.006) muscle. In the LVG, the EMG_rms decreased significantly in the DE (P = 0.009) and FCR (P = 0.006) muscles.

Conclusion

Synchronous WBV acutely increased GH and testosterone serum concentrations and decreased the MVC and their respective maximal EMG_rms activities, which indicated a possible central fatigue effect. Interestingly, only the GH response was dependent on the acceleration with respect to the subjects' responsiveness.

Corticotrophin-releasing factor and urocortin inhibit system A activity in term human placental villous explants

Plasma corticotrophin-releasing factor (CRF) and urocortin are elevated in preterm labour and/or fetal growth restriction (FGR). FGR is associated with reduced placental system A amino acid transporter activity and in vitro data suggest altered endocrine status could be responsible. Here we test the hypothesis that CRF and urocortin inhibit placental system A activity. Chronic (48h) exposure of term placental villous explants to these hormones (10(-7)M) significantly reduced system A activity (Na(+)-dependent (14)C-methylaminoisobutyric acid uptake), whereas 1h exposure had no effect. We propose elevated CRF and urocortin contribute to FGR through negative regulation of placental system A activity.

Transcriptome changes in the cambial region of poplar (Populus alba L.) in response to water deficit

A transcriptome analysis of the Populus alba cambial region was performed with the aim of elucidating the gene network underlying the response to water deficit within the cambium and differentiating derivative cambial cells. Water stress was induced in 1-year-old P. alba plants by withholding water for 9 days. At that time, leaf predawn water potential fell to -0.8 MPa, resulting in a significant reduction in stomatal conductance, CO(2) assimilation and a consistent increment of stem shrinkage. These effects were almost fully reversed by re-hydration. The water deficit resulted in changes in gene expression that affected several functional categories, such as protein metabolism, cell wall metabolism, stress response, transporters and transcriptional regulation. The function of up- and down-regulated genes is discussed considering the physiological response of the plants to water deficit.

A new completely flexible ring for mitral valve annuloplasty: the "Rama-Valvuloplasty-Ring". Five-year Pitié Salpétrière experience

The aim of this study was to analyze the effects about the use of a new completely flexible ring for mitral valve anuloplasty, the "Rama-Valvuloplasty-ring", in 182 patients operated on in the Pitié-Salpétrière Hospital, Paris, France for mitral valve regurgitation (MVR). From January 1998 to December 2003, 182 patients with mitral regurgitation (MR) underwent mitral reconstructive surgery at our institution with the "Rama-Valvuloplasty-Ring". This group was made up of 117 men (64.3%) and 65 women (35.7%). The age ranged from 19 to 87 years (mean 62.51 +/- 8.2 years). The patients surviving the operation were the subject of a prospective follow-up. In the preoperative stage sinus rhythm was found in 71.97% (131) of patients and atrial fibrillation in the remaining 28.03% (51) of patients. The mean NYHA FC was 2.9 +/- 1.7 and subdivided as follows: 65 patients in FC I-II (35.72%), 104 patients in FC III (57.14%) and 13 patients in FC IV (7.14%). Most of the patients have shown, in the preoperative echocardiogram, grade II M.R. (46.15% N. 84) and grade III M.R. (29.12%, N.53); 24.72% of the patients (N. 45) had grade IV M.R. The mean E.F. was 42.8 +/- 9.7%. Left ventricular end diastolic diameter (LVEDD) was 57.7 +/- 9.7 mm. The causes of mitral valve insufficiency were degenerative disease in 141 patients (77.47%), post-ischemic disease in 21 patients (11.53%), rheumatic valvular disease in 11 patients (6.05%) and infectious endocarditis in 9 patients (4.95%). All the patients were operated using the Rama-Valvuloplasty-Ring. Ring sizes most commonly used were 30 mm and 32 mm, respectively in 92 patients (50.55%) and 41 patients (22.54%), followed by 28 mm (43 patients, 23.62%), 34 mm (5 patients, 2.74%), 36 mm (1 patient, 0.55%). The surgical tecnique was valve quadrangular resection in 103 patients (56.60%), triangular resection in 57 patients (31.32%) and no valve resection in 22 patients (12.08%). Among the above, 89 patients (48.90%) underwent an associated intervention as follows: 44 patients (24.18%) underwent coronary revascularization: 18 patients (9.89%) with single by-pass surgery, 21 patients (11.54%) with double by-pass, 5 patients with triple by-pass (2.75%); 42 patients (23.07) underwent aortic valve replacement (AVR); 3 patients (1.65%) underwent aortic repair. Early postoperative mortality was 2.19% (4 of 182 patients). Early postoperative echocardiographic control showed MR grade 0 in 142 patients (79.78%) and grade I in 36 (20.22%) with mean grade 0.4 +/- 0.12; no patients with grade III or IV. Therefore, there was no mitral annuloplasty failure requiring valve replacement (MVR). During the follow-up there were 12 late deaths (12 of 178 patients, 6.74%). Only one death was valve-related (thrombosis) whereas the other 11 ones were non cardiac-related deaths (subdural frontal haematoma, septic shock). Postoperative transthoracic echocardiogram data were available in 166 patients at 5 years: the presence of postoperative MR was evaluated and severity was graded as mild in 33 patients (19.88%), moderate in 18 patients (10.84%), severe in 3 (1.81%) patients. There was no MR in the other 112 patients (67.47%); LVEDD was 49.4 +/- 6.5 mm; EF was 51.8 +/- 4.3%. The mean NYHA FC was 0.8 +/- 0.4. Only one patient was reoperated on during the follow-up because of mitral annuloplasty failure with MVR. In conclusion, mid-term 5-years follow up is good for patients operated on with the new completely flexible Rama-Valvuloplasty-Ring for mitral annuloplasty. This study has also verified the advantage about the Rama-Valvuloplasty-Ring use in the preservation of native valve apparatus.

The endovascular treatment of traumatic isthmic aortic rupture: three years follow-up

The isthmic aortic rupture represents the main cause of death in car crash accidents, because of closed chest trauma. Early medical and surgical care and endovascular prosthesis treatment with semi-invasive method can improve short and mid term survival. Nine patients with traumatic isthmic aortic rupture underwent endoprosthesis aortic implantation. All the patients were male, mean age 42.48 +/- 17.66 years. Operations included 5 acute cases and 4 chronic cases (chance diagnosis). In all cases the diagnosis was performed by tomodensitometric exam. Cloth prostheses were used (self-expansible Goretex- or Dacron-stent). Three years after the endoprosthesis implantation, we obtained the complete thrombosis of the false aortic lumen in all patients, both acute and chronic, as well as the levelling of the false aneurysms without complications of any kind.

Long-term dark rearing induces permanent reorganization in retinal circuitry

Recent data challenged the assumption that light has little effect on retina development. Here, we report evidence that dark rearing permanently changes the synaptic input to GCs. A reduced spontaneous postsynaptic currents (SPSCs) frequency was found in retinal GCs from rats born and raised in the dark for three months. Glutamate antagonists (CNQX and AP-5) reversibly reduced SPSCs frequency in control and dark-reared (DR) retinae. The GABA antagonist picrotoxin (PTX) reduced SPSCs frequency in control retinas, but increased SPSCs frequency in DR, mainly by presynaptic action on excitatory currents. In DR animals exposed to normal cyclic light for 3 months, SPSCs frequency remained lower then in control rats and increased following PTX, suggesting that long-term dark rearing induces permanent modifications of the retinal circuitry. Our results strongly support the idea that light stimulation plays a role in establishing normal synaptic input to GCs.

Maternal plasma corticotropin-releasing factor (CRF) and CRF-binding protein (CRF-BP) levels in post-term pregnancy: effect of prostaglandin administration

OBJECTIVE

Placental corticotropin-releasing factor (CRF) affects myometrial contractility and the secretion of several uterotonins such as prostaglandins (PGs); however, the activity of CRF is counteracted by CRF-binding protein (CRF-BP). At term and pre-term labor, CRF levels in maternal plasma are highest whereas those of CRF-BP are falling, and the cause of this fall is unknown. Thus, in this study, we investigated the effect of PG administration for labor induction on maternal plasma CRF and CRF-BP concentrations.

DESIGN

Maternal plasma CRF and CRF-BP levels were assayed before and after (2 h later) induction of labor by intracervical administration of prostaglandin E(2) (PGE(2)), and at delivery in a group of healthy post-term pregnancies (n=18). Controls were women at term out of labor (n=22), who subsequently progressed to deliver a healthy singleton baby.

METHODS

CRF was measured by two-site immunoradiometric assay, and CRF-BP was assayed by radioimmunoassay.

RESULTS

Maternal plasma CRF levels were significantly (P<0.0001) lower and CRF-BP significantly (P<0.0005) higher in post-term than in term pregnancies. With respect to induction of labor, 2 mg PGE(2) were sufficient to increase maternal plasma CRF levels at delivery (P<0.005). While 0.5 mg PGE(2) significantly decreased maternal plasma CRF-BP levels at delivery (P<0.001), 2.0 mg PGE(2) significantly reduced CRF-BP concentrations both after 2 h (P<0.05) and at delivery (P<0.0001).

CONCLUSIONS

In the light of the well-known stimulation of prostaglandin release by CRF, these data suggest a positive feedback effect of PGE(2) on maternal CRF release during induced labor.

Placental neurokinin B mRNA expression increases at preterm labor

INTRODUCTION

Neurokinin B (NKB) is a neuropeptide belonging to the family of tachykinins-related peptides that elicits contractility of human myometrial strips in vitro. The present study evaluates whether placental mRNA and peptide expression of NKB change in women at preterm labor.

METHODS

A group of 26 women with singleton pregnancies were enrolled in the study. Placental tissue specimens were collected from pregnant women delivering after elective cesarean section, after labor at term, or after preterm labor. Changes in placental NKB mRNA and protein expression were evaluated by real-time quantitative RT-PCR analysis and by immunofluorescence respectively.

RESULTS

Placental mRNA expression of NKB was significantly higher after term and preterm labor (P<0.001) than cesarean section, and highest after preterm labor. Immunofluorescent staining in placentas from preterm or term labor was more intense than after cesarean section (P<0.001). In particular, NKB protein expression was higher in placentas collected after preterm labor than those collected after term labor.

DISCUSSION

Neurokinin B mRNA and protein are highly expressed in placenta at term and preterm labor; thus, the involvement of this neuropeptide in the events cascade leading to parturition may be suggested.

Growth factors and their receptors: fundamental molecules for human placental development

In this review we present data concerning the localization of some important growth factors and their receptors in the human placenta. We focus our attention on molecules playing a fundamental role in angiogenesis and morphologic processes as beta-FGF, EGF and TGF-beta. The distribution of these growth factors and their receptors in the placental villi during gestation suggests that these molecules play a pivotal role in growth and differentiation of the villous tree.

Stimulation of chemokine CXC receptor 4 induces synaptic depression of evoked parallel fibers inputs onto Purkinje neurons in mouse cerebellum

In the present work, we studied the effects of the stimulation of the chemokine CXC receptor 4 (CXCR4) by the stromal-derived cell growth factor-1alpha (SDF-1alpha) on the evoked excitatory postsynaptic current. This was generated in Purkinje neurons (PN) from mouse cerebellar slices by the stimulation of parallel fibers. It was found that the amplitude of EPSC was reversibly reduced by SDF-1alpha application. This effect was dose-dependent (IC(50)=0.34 nM) and was abolished by the anti-CXCR4 monoclonal antibody (mAb) 12G5. This SDF-1alpha-induced synaptic depression was caused by a decrease of evoked glutamate release, rather than a decrease in the postsynaptic glutamate receptor (GluR) sensitivity, as the mean amplitude of the spontaneous EPSCs was not influenced by chemokine application. Moreover, NMDA receptors (NMDARs) are involved in EPSC depression being inhibited by the NMDAR blocker 2-amino-5-phosphonopentanoic acid (AP-5). The mechanisms by which SDF-1alpha modulates neurotransmission in the cerebellar cortex are discussed.

Zinc permeates mouse muscle ACh receptor channels expressed in BOSC 23 cells and affects channel function

1. The influx of Zn2+ through the channels of fetal and adult mouse muscle nicotinic acetylcholine receptors (gamma- and epsilon-AChRs) and its effects on receptor function were studied in transiently transfected human BOSC 23 cells, by combining patch-clamp recordings with digital fluorescence microscopy. 2. ACh-induced whole-cell currents were reversibly reduced by external ZnCl2, with half-maximal inhibitory concentrations of 3 and 1 mM for gamma- and epsilon-AChRs, respectively. 3. Both gamma- and epsilon-AChR channels were permeable to Zn2+, as shown by fluorescence measurements using Zn2+-sensitive dyes. The fractional current carried by Zn2+ (Pf,Zn; 0.5 mM Zn2+ in Ca2+- and Mg2+-free medium) through gamma- and epsilon">-AChR channels was 1.7 and 4 %, respectively. 4. Pf,Zn increased with the concentration of ZnCl2, but was little affected by physiological concentrations of Ca2+ and Mg2+ in the external medium. 5. The conductance of ACh-evoked unitary events, measured by cell-attached or outside-out recordings, decreased when the patched membrane was exposed to ZnCl2 (1 or 3 mM). Simultaneous application of ACh and Zn2+ to the extra-patch membrane lengthened channel open duration (tau op) by 50%. No obvious increment of tau op was observed following exposure of inside-out patches to Zn2+. 6. The possible physiological relevance of zinc-induced modulation of AChR channels is discussed.

Comparative XANES study of serotransferrin and ovotransferrin at Cu K-edge: evidence of interactions among the metal sites

The Cu site structure of human serotransferrin and hen ovotransferrin using XANES spectroscopy has been investigated. Although the transferrin family proteins have been extensively studied, the results reported herein are the first concerning the structure of the metal site in C-terminal and N-terminal in the whole protein. Our structural data show that these proteins differ with regard to the independence of the two binding sites and the geometry of copper coordination, ranging from a poorly to a significantly distorted octahedron.

SDF-1alpha-mediated modulation of synaptic transmission in rat cerebellum

The functional expression of the seven-transmembrane domain G protein-coupled chemokine receptor CXCR-4/fusin in rat nerve cell was demonstrated by staining with a polyclonal anti-CXCR-4 Ab, and by evaluating the calcium responses to the physiological agonist stromal-derived cell factor-1alpha (SDF-1alpha) in both cerebellar granule cells in culture and Purkinje neurons (PNs) in cerebellar slices. Cerebellar glial, granule and Purkinje cells showed a pronounced staining for CXCR-4. Furthermore, cultured granule cells exhibited Ca2+ transients elicited by the application of SDF-1alpha, both in cell bodies and in neuronal processes. Whole-cell patch-clamped PNs in cerebellar slices responded to SDF-1alpha application by a slow inward current followed by an increase of both intracellular Ca2+ level and spontaneous synaptic activity. In particular, the SDF-1alpha-induced slow inward current was considerably reduced by ionotropic glutamate receptor blockers, but developed fully in a medium in which synaptic transmission was inhibited, indicating that this current might be, at least in part, mediated by extrasynaptic glutamate, possibly released from the surrounding glial and/or nerve cells. Taken together, these findings indicate a functional involvement of CXCR-4 in the modulation of synaptic transmission, adding another member to the repertoire of the chemokine receptors exerting a neuromodulatory role in the cerebellum.

The chemokine growth-related gene product beta protects rat cerebellar granule cells from apoptotic cell death through alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors

Cultured cerebellar granule neurons are widely used as a cellular model to study mechanisms of neuronal cell death because they undergo programmed cell death when switched from a culture medium containing 25 mM to one containing 5 mM K(+). We have found that the growth-related gene product beta (GRObeta) partially prevents the K(+)-depletion-induced cell death, and that the neuroprotective action of GRObeta on granule cells is mediated through the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) type of ionotropic glutamate receptors. GRObeta-induced survival was suppressed by 6-cyano-7-nitroquinoxaline-2,3-dione, which is a specific antagonist of AMPA/kainate receptors; it was not affected by the inhibitor of N-methyl-D-aspartate receptors, 2-amino-5-phosphonopentanoic acid, and was comparable to the survival of granule cells induced by AMPA (10 microM) treatment. Moreover, GRObeta-induced neuroprotection was abolished when granule cells were treated with antisense oligonucleotides specific for the AMPA receptor subunits, which significantly reduced receptor expression, as verified by Western blot analysis with subunit-specific antibodies and by granule cell electrophysiological sensitivity to AMPA. Our data demonstrate that GRObeta is neurotrophic for cerebellar granule cells, and that this activity depends on AMPA receptors.

Energy metabolism of human LoVo colon carcinoma cells: correlation to drug resistance and influence of lonidamine

The relationship between modification of energy metabolism and extent of drug resistance was investigated in two sublines (LoVoDX and LoVoDX10) from human LoVo colon carcinoma cells that exhibit different degrees of resistance to doxorubicin. Results indicated that the extent of alteration in energy metabolism strictly correlated with degree of resistance. In LoVoDX cells, only 14CO2 production was enhanced, whereas in the more resistant LoVoDX10 cells, both 14CO2 and aerobic lactate production were stimulated. The basal and glucose-supported efflux rate and the amount of drug extruded by LoVoDX10 cells were significantly higher than in the resistant LoVoDX cells. Because the expression of surface P-170 glycoprotein was similar in both cell lines, this phenomenon was attributed to increased efflux pump activity resulting from greater ATP availability. Inhibition of 14CO2 production, aerobic glycolysis, and clonogenic activity by lonidamine (LND) increased with enhancement of the energy metabolism. Moreover, LND, by affecting energy-yielding processes, reduced intracellular ATP content, lowered the energy supply to the ATP-driven efflux pump, and inhibited, almost completely, doxorubicin extrusion by resistant LoVo cells. These findings strongly suggest that LND, currently used in tumor therapy, reduces drug resistance by restoring the capacity to accumulate and retain drug of cells with the MDR phenotype that overexpress P-170.

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.