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1.
J Neurosci Methods ; 407: 110158, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38703797

RESUMEN

BACKGROUND: The serotonergic system modulates brain processes via functionally distinct subpopulations of neurons with heterogeneous properties, including their electrophysiological activity. In extracellular recordings, serotonergic neurons to be investigated for their functional properties are commonly identified on the basis of "typical" features of their activity, i.e. slow regular firing and relatively long duration of action potentials. Thus, due to the lack of equally robust criteria for discriminating serotonergic neurons with "atypical" features from non-serotonergic cells, the physiological relevance of the diversity of serotonergic neuron activities results largely understudied. NEW METHODS: We propose deep learning models capable of discriminating typical and atypical serotonergic neurons from non-serotonergic cells with high accuracy. The research utilized electrophysiological in vitro recordings from serotonergic neurons identified by the expression of fluorescent proteins specific to the serotonergic system and non-serotonergic cells. These recordings formed the basis of the training, validation, and testing data for the deep learning models. The study employed convolutional neural networks (CNNs), known for their efficiency in pattern recognition, to classify neurons based on the specific characteristics of their action potentials. RESULTS: The models were trained on a dataset comprising 27,108 original action potential samples, alongside an extensive set of 12 million synthetic action potential samples, designed to mitigate the risk of overfitting the background noise in the recordings, a potential source of bias. Results show that the models achieved high accuracy and were further validated on "non-homogeneous" data, i.e., data unknown to the model and collected on different days from those used for the training of the model, to confirm their robustness and reliability in real-world experimental conditions. COMPARISON WITH EXISTING METHODS: Conventional methods for identifying serotonergic neurons allow recognition of serotonergic neurons defined as typical. Our model based on the analysis of the sole action potential reliably recognizes over 94% of serotonergic neurons including those with atypical features of spike and activity. CONCLUSION: The model is ready for use in experiments conducted with the here described recording parameters. We release the codes and procedures allowing to adapt the model to different acquisition parameters or for identification of other classes of spontaneously active neurons.


Asunto(s)
Potenciales de Acción , Aprendizaje Profundo , Neuronas Serotoninérgicas , Neuronas Serotoninérgicas/fisiología , Animales , Potenciales de Acción/fisiología , Modelos Neurológicos , Ratones
2.
G Ital Cardiol (Rome) ; 21(6 Suppl 1): 15S-20S, 2020 06.
Artículo en Italiano | MEDLINE | ID: mdl-32469340

RESUMEN

Device loss or entrapment during percutaneous coronary interventions (PCI) is a rare circumstance whose incidence has decreased over time mainly because of device improvements. Nevertheless, they still represent fearful complications also and above all because the operators may be unfamiliar with rescue and retrieval techniques. The devices that most frequently experience loss or entrapment are stents, followed by angioplasty balloons, burrs for rotational atherectomy, guidewires and microcatheters. In this review we will illustrate the risk factors for device loss and the main retrieval techniques, as described in the literature or stemmed from our experience as high-volume PCI center.


Asunto(s)
Remoción de Dispositivos/métodos , Cuerpos Extraños/terapia , Intervención Coronaria Percutánea/efectos adversos , Falla de Equipo , Cuerpos Extraños/complicaciones , Humanos , Intervención Coronaria Percutánea/instrumentación , Factores de Riesgo , Stents/efectos adversos
3.
Circ Cardiovasc Interv ; 13(3): e008325, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-32102566

RESUMEN

BACKGROUND: There are limited data regarding the impact of final kissing balloon (FKI) in patients treated with percutaneous coronary intervention using ultrathin stents in left main or bifurcations. METHODS: All patients undergoing left main or bifurcations percutaneous coronary intervention enrolled in the RAIN registry (Very Thin Stents for Patients With MAIN or BiF in Real Life: The RAIN, a Multicenter Study) evaluating ultrathin stents were included. Major adverse cardiac event (a composite of all-cause death, myocardial infarction, target lesion revascularization, and stent thrombosis) was the primary end point, while its components, along with target vessel revascularization, were the secondary end points. The main analysis was performed comparing patients with and without FKI after adjustment with inverse probability of treatment weighting. Subgroup analyses were performed according to FKI (short [<3 mm] versus long overlap), strategy (provisional versus 2-stent), routine versus bail-out FKI, and the use of imaging and proximal optimization technique. RESULTS: Two thousand seven hundred forty-two patients were included. At 16 months (8-20) follow-up, inverse probability of treatment weighting adjusted rates of major adverse cardiac event were similar between FKI and no-FKI group (15.1% versus 15.5%; P=0.967), this result did not change with use of imaging, proximal optimization technique, or routine versus bail-out FKI. In the 2-stent subgroup, FKI was associated with lower rates of target vessel revascularization (7.8% versus 15.9%; P=0.030) and target lesion revascularization (7.3% versus 15.2%; P=0.032). Short overlap FKI was associated with a lower rate of target lesion revascularization compared with no FKI (2.6% versus 5.4%; P=0.034), while long overlap was not (6.8% versus 5.4%; P=0.567). CONCLUSIONS: In patients with bifurcations or unprotected left main treated with ultrathin stents, short overlap FKI is associated with less restenosis. In a 2-stent strategy, FKI was associated with less target vessel revascularization and restenosis. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03544294.


Asunto(s)
Angioplastia Coronaria con Balón/instrumentación , Enfermedad de la Arteria Coronaria/terapia , Diseño de Prótesis , Stents , Anciano , Anciano de 80 o más Años , Angioplastia Coronaria con Balón/mortalidad , Enfermedad de la Arteria Coronaria/mortalidad , Reestenosis Coronaria/etiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Sistema de Registros , Estudios Retrospectivos , Factores de Riesgo , Resultado del Tratamiento
4.
Catheter Cardiovasc Interv ; 95(3): 522-529, 2020 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-31385427

RESUMEN

OBJECTIVES: Evaluate safety and efficacy of polymer-free biolimus-eluting stents (PF-BESs) versus ultrathin stents in unprotected left main (ULM) or bifurcation. BACKGROUND: PF-BESs due to reduced length of dual antiplatelet therapy (DAPT) are increasingly used. However, there are limited data about safety and efficacy for ULM or bifurcation. METHODS: We selected all-patients treated for ULM or bifurcation from two multicenter real life registries (RAIN [NCT03544294] evaluating ultrathin stents, CHANCE [NCT03622203] appraising PF-BES). After propensity score with matching, the primary endpoint was major adverse cardiac events (MACE; a composite of all-cause death, myocardial infarction, target lesion revascularization [TLR], and stent thrombosis [ST]), while its components along with target vessel revascularization (TVR) secondary endpoints. RESULTS: Three thousand and three patients treated with ultrathin stents and 446 with PF-BESs, resulting respectively in 562 and 281 after propensity score with matching (33 and 22%, respectively, with ULM disease). After 12 (8-20) months, rates of MACE were similar (9 vs. 8%, p = 0.56) without difference in TLR and ST (3.0 vs. 1.7%, p = .19 and 1.8 vs. 1.1%, p = .42). These results were consistent for ULM group (3 vs. 1.7% and 1.8 vs. 1.1%, p = .49 and .76), for non-ULM group (2.1 vs. 3.4%, p = .56 and 1.2 vs. 1.7%, p = .78) and for two-stent strategy (8.7 vs. 4.5% and 4.3 vs. 3.2%, p = .75 and .91). Among patients treated with 1 month of DAPT in both groups, those with ultrathin stents experienced higher rates of MACE related to all-cause death (22 vs. 12%, p = .04) with higher although not significant rates of ST (3 vs. 0%, p = .45). CONCLUSIONS: PF-BES implanted on ULM or BiF offered freedom from TLR and ST comparable to ultrathin stents. PF-BESs patients assuming DAPT for 1 month experienced a lower despite not significant incidence of ST.


Asunto(s)
Fármacos Cardiovasculares/administración & dosificación , Enfermedad de la Arteria Coronaria/terapia , Stents Liberadores de Fármacos , Intervención Coronaria Percutánea/instrumentación , Sirolimus/análogos & derivados , Anciano , Anciano de 80 o más Años , Fármacos Cardiovasculares/efectos adversos , Protocolos Clínicos , Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Enfermedad de la Arteria Coronaria/mortalidad , Enfermedad de la Arteria Coronaria/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Intervención Coronaria Percutánea/efectos adversos , Intervención Coronaria Percutánea/mortalidad , Puntaje de Propensión , Diseño de Prótesis , Sistema de Registros , Estudios Retrospectivos , Medición de Riesgo , Factores de Riesgo , Sirolimus/administración & dosificación , Sirolimus/efectos adversos , Factores de Tiempo
5.
Int J Cardiol ; 301: 200-206, 2020 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-31785951

RESUMEN

BACKGROUND: The PRECISE-DAPT and PARIS risk scores (RSs) were recently developed to help clinicians at individualizing the optimal dual antiplatelet therapy duration (DAPT) after percutaneous coronary intervention (PCI). Nevertheless, external validation of these RSs it has not yet been performed in ACS (acute coronary syndrome) patients treated with prasugrel or ticagrelor in a real- world scenario. METHODS: 4424 ACS patients who underwent PCI and survived to hospital discharge, from January 2012 to December 2016 at 12 European centers, were included. PRECISE-DAPT and PARIS bleeding RS, as well as PARIS ischemic RS, were computed, and their performance at predicting major bleeding (MB; BARC type 3 or 5) and ischemic events (MI and stent thrombosis) during follow up was compared. RESULTS: After a median follow-up of 14 (interquartile range 12-20.9) months, 83 (1.88%) patients developed MB and 133 (3.0%) suffered an ischemic episode. PRECISE-DAPT performed better than PARIS bleeding RS (c-statistic = 0.653 vs. 0.593; p = .01 for comparison) in predicting MB. The RSs performance for MB prediction remained consistent in STEMI patients (c-statistic = 0.632 vs 0.575) or in those treated with prasugrel (c-statistic = 0.623 vs 0.586). PARIS ischemic RS exhibited superior discrimination in predicting ischemic complications compared to PRECISE-DAPT (c-statistic = 0.604 vs 0.568 p = .05 for comparison). CONCLUSION: Our data provide support to the use of PRECISE-DAPT in MB risk stratification for patients receiving DAPT in form of aspirin and prasugrel or ticagrelor whereas the PARIS ischemic RS has potential to complement the risk prediction with respect to ischemic events.


Asunto(s)
Síndrome Coronario Agudo/cirugía , Intervención Coronaria Percutánea/efectos adversos , Inhibidores de Agregación Plaquetaria/uso terapéutico , Complicaciones Posoperatorias/epidemiología , Clorhidrato de Prasugrel/uso terapéutico , Ticagrelor/uso terapéutico , Anciano , Aspirina/uso terapéutico , Quimioterapia Combinada , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Estudios Retrospectivos , Medición de Riesgo , Resultado del Tratamiento
6.
J Cardiovasc Med (Hagerstown) ; 19(10): 586-596, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30045086

RESUMEN

INTRODUCTION: Different devices have been released for closure of femoral vascular access after coronary angiography or percutaneous coronary intervention, whereas evidence about their efficacy and safety when compared with manual compression or head to head is lacking, especially across different diameters of sheaths, age and sex. RESULTS: A total of 30 studies were included in the analysis. Manual compression was evaluated as the control group in all of the included studies (5620 patients), Angioseal in 15 studies (17-29) (1812 patients), Exoseal in two studies (30-31) (1773 patients), Perclose in six (29, 32-37) (849 patients), Vasoseal in eight (36, 38-43) (699 patients), DUETT in one study (44) (392 patients), StarClose in two studies (23, 45) (334 patients), Techstar in two studies (37, 46) (252 patients) and extravascular staple in one study (47) (242 patients). At network meta-analysis, all the devices resulted as not superior to manual compression to reduce all vascular complications, and these results did not vary at metaregression for age, sex and diameter of sheaths. Manual compression significantly increased time to hemostasis when compared with Femoseal (5.72; 1.91-19.10), Vasoseal (5.11; 2.32-11.33), Perclose (3.46; 1.70-7.06), Angioseal (14.95; 7.84-28.57) and Techstar (9.78; 1.81-53.65), while was similar to StarClose, DUETT and Exoseal. CONCLUSION: Different vascular devices for closure of femoral access did not results superior to manual compression to reduce complications, whereas offered a shorted time to hemostasis. StarClose was the device with the highest probability to perform best in terms of complication, whereas Angioseal was superior in terms of reduction of time to hemostasis.


Asunto(s)
Cateterismo Periférico/métodos , Arteria Femoral , Hemorragia/prevención & control , Técnicas Hemostáticas/instrumentación , Intervención Coronaria Percutánea/métodos , Dispositivos de Cierre Vascular , Adulto , Anciano , Cateterismo Periférico/efectos adversos , Diseño de Equipo , Femenino , Hemorragia/sangre , Hemorragia/etiología , Hemostasis , Técnicas Hemostáticas/efectos adversos , Humanos , Masculino , Persona de Mediana Edad , Intervención Coronaria Percutánea/efectos adversos , Punciones , Factores de Riesgo , Factores de Tiempo , Resultado del Tratamiento
7.
Am J Cardiol ; 117(11): 1714-23, 2016 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-27134057

RESUMEN

The purpose of the study was to evaluate the optimal duration of dual antiplatelet therapy (DAPT) after percutaneous coronary intervention, especially in the era of second-generation drug-eluting stents (DES). The work was conducted from November 2014 to April 2015. All randomized controlled trials comparing short (<12 months) versus long (≥12 months) DAPT in patients treated with second-generation DES were analyzed. Sensitivity analyses were performed for length of DAPT and type of DES. All-cause death was the primary end point, whereas cardiovascular death, myocardial infarction (MI), stent thrombosis (ST), and major bleeding were secondary end points. Results were pooled and compared with random-effect models and meta-regression analysis. Eight randomized controlled trials with 18,810 randomized patients were included. The studies compared 3 versus 12 months of DAPT (2 trials), 6 versus 12 months (3 trials), 6 versus 24 months (1 trial), 12 versus 24 months (1 trial), and 12 versus 30 months (1 trial). Comparing short versus long DAPT, there were no significant differences in all-cause death (odds ratio [OR] 0.87; 95% confidence interval [CI] 0.66 to 1.44), cardiovascular death (OR 0.95; 95% CI 0.65 to 1.37), and ST (OR 1.20; 95% CI 0.79 to 1.83), and no differences were present when considering everolimus-eluting and fast-release zotarolimus-eluting stents separately. Shorter DAPT was inferior to longer DAPT in preventing MI (OR 1.35; 95% CI 1.03 to 1.77). Conversely, major bleeding was reduced by shorter DAPT (OR 0.60; 95% CI 0.42 to 0.96). Baseline features did not influence these results in meta-regression analysis. In conclusion, DAPT for ≤6 months is reasonable for patients treated with everolimus-eluting and fast-release zotarolimus-eluting stents, with the benefit of less major bleeding at the cost of increased MI, with similar survival and ST rates. An individualized patient approach to DAPT duration should take into account the competing risks of bleeding and ischemic complications after present-generation DES.


Asunto(s)
Enfermedad de la Arteria Coronaria/terapia , Stents Liberadores de Fármacos , Hemorragia/inducido químicamente , Inhibidores de Agregación Plaquetaria/administración & dosificación , Quimioterapia Combinada , Salud Global , Hemorragia/epidemiología , Humanos , Incidencia , Intervención Coronaria Percutánea , Inhibidores de Agregación Plaquetaria/efectos adversos , Diseño de Prótesis
8.
Circ Cardiovasc Interv ; 9(1): e002896, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26755572

RESUMEN

BACKGROUND: The most suitable approach for patients with aspirin hypersensitivity undergoing percutaneous coronary intervention remains to be assessed. METHODS AND RESULTS: Pubmed, Google Scholar, and Cochrane were systematically searched for papers describing protocols about aspirin hypersensitivity in the percutaneous coronary intervention setting. Discharge from hospital with aspirin was the primary end point, whereas rates of adverse reactions being a secondary outcome. An online international survey was performed to critically analyze rates of aspirin hypersensitivity and its medical and interventional management. Eleven studies with 283 patients were included. An endovenous desensitization protocol was performed on one of them, with high efficacy rate (98%) and a low adverse reaction rate when compared with oral administration. No significant differences were reported among the oral protocols in terms of efficacy (less versus more fractionated [95.8% {95.4%-96.2%} versus 95.9% {95.2-96.5%}]), whereas higher incidence of rash and angioedema were reported for protocols with <6 doses escalation (2.6% [1.1%-4.1%] versus 2.6% [1.9%-3.2%]). In the survey, we collected answer from 86 physician of the 100 interviewed. Fifty-six percent of them managed aspirin hypersensitivity changing the therapeutic regimen (eg, clopidogrel monotherapy and indobufen). Despite the previous safety data, desensitization protocols were adopted by only 42% of surveyed cardiologist. CONCLUSIONS: Available protocols for aspirin hypersensitivity are effective and safe, representing a feasible approach for patients needing dual antiplatelet therapy.


Asunto(s)
Aspirina/efectos adversos , Protocolos Clínicos , Enfermedad de la Arteria Coronaria/terapia , Hipersensibilidad a las Drogas/epidemiología , Intervención Coronaria Percutánea , Cuidados Preoperatorios , Encuestas y Cuestionarios , Humanos , Incidencia , Inhibidores de Agregación Plaquetaria/efectos adversos
9.
Dalton Trans ; 42(2): 407-21, 2013 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-23069730

RESUMEN

The reaction of [Ni(9)C(CO)(17)](2-) with [Cu(CH(3)CN)(4)][BF(4)] (1.1-1.5 equiv.) afforded the first Ni-Cu carbide carbonyl cluster, i.e., [H(2)Ni(30)C(4)(CO)(34){Cu(CH(3)CN)}(2)](4-) ([H(2)1](4-)). This has been crystallised in a pure form with miscellaneous [NR(4)](+) (R = Me, Et) cations, as well as co-crystallised with [H(2)Ni(29)C(4)(CO)(33){Cu(CH(3)CN)}(2)](4-) ([H(2)2](4-)) which differs from [H(2)1](4-) by a missing Ni(CO) fragment. By increasing the [Cu(CH(3)CN)(4)](+)/[Ni(9)C(CO)(17)](2-) ratio to 1.7-1.8, the closely related [H(2)Ni(30)C(4)(CO)(35){Cu(CH(3)CN)}(2)](2-) ([H(2)3](2-)), [H(2)Ni(29)C(4)(CO)(34){Cu(CH(3)CN)}(2)](2-) ([H(2)4](2-)), and [H(2)Ni(29)C(4)(CO)(32)(CH(3)CN)(2){Cu(CH(3)CN)}(2)](2-) ([H(2)5](2-)) dianions have been obtained. Replacement of Cu-bonded CH(3)CN with p-NCC(6)H(4)CN afforded, after protonation of the tetra-anion, mixtures of [H(3)Ni(30)C(4)(CO)(34){Cu(NCC(6)H(4)CN)}(2)](3-) ([H(3)6](3-)) and [H(3)Ni(29)C(4)(CO)(33){Cu(NCC(6)H(4)CN)}(2)](3-) ([H(3)7](3-)). The species 1-7 display a common Ni(28)C(4)Cu(2) core and differ for the charge, the presence of additional Ni atoms, the number and nature of the ligands, even though they are obtained under similar experimental conditions and often in mixtures. Their nature in solution has been investigated via FT-IR, chemical and electrochemical methods. Electrochemical studies, besides confirming the poly-hydride nature of these clusters, show that they undergo different redox processes with features of chemical reversibility, and this might be taken as proof of the incipient metallisation of their metal cores.

10.
Intensive Care Med ; 36(12): 2125-31, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-20689922

RESUMEN

PURPOSE: To demonstrate in a two-compartment heterogeneous mechanical model of the lung how different loads applied to one compartment, while the other is kept constant, would modify gas distribution between the two pathways under high-frequency percussive ventilation (HFPV). Additionally, these results were compared with those generated in the same model by pressure-controlled ventilation (PCV). METHODS: Analysis was based on a Siemens lung simulator, representing a fixed branch of the system with an elastance equal to 45 cmH(2)O/L and a resistance of 20 cmH(2)O/L/s, and a single-compartment lung simulator, representing a variable pathway of the model, presenting three elastic loads varying between 35 and 85 cmH(2)O/L and three resistive loads varying between 5 and 50 cmH(2)O/L/s. Each simulator represented one compartment of the model connected to a central airway that was ventilated with either a volumetric diffusive respirator (VDR-4; Percussionaire Corporation, Sandpoint, ID, USA) or a Siemens Servo 900c ventilator. Flow and pressures were measured in each branch of the model under nine conditions representing the combinations of three elastic and three resistive loads (variable branch) while the loads in the other pathway were kept constant. RESULTS: HFPV was able to avoid hyperinflation and reduce tidal volume in a bicompartmental heterogeneous lung model. Under HFPV, gas distribution between the two compartments was not constrained by their time constants. PCV yielded gas distribution as determined by the time constant of each compartment. CONCLUSIONS: HFPV accommodated volume distribution without overinflating compartments with low time constants, thus possibly presenting a potential protective behavior in mechanically heterogeneous lungs.


Asunto(s)
Ventilación de Alta Frecuencia , Modelos Biológicos , Respiración
11.
Dalton Trans ; (21): 4245-51, 2009 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-19452075

RESUMEN

The new tetra-acetylide carbonyl clusters [H(4-n)Ni(22)(C(2))(4)(CO)(28)(CdBr)(2)](n-) (n = 2-4) have been prepared by reacting [Ni(10)C(2)(CO)(15)](2-) with a large excess of CdBr(2).xH(2)O and the molecular structure of the di-anion [H(2)Ni(22)(C(2))(4)(CO)(28)(CdBr)(2)](2-) has been fully elucidated by means of X-ray crystallography. The corresponding [HNi(22)(C(2))(4)(CO)(28)(CdBr)(2)](3-) and [Ni(22)(C(2))(4)(CO)(28)(CdBr)(2)](4-) conjugated bases are quantitatively obtained upon dissolution of [H(2)Ni(22)(C(2))(4)(CO)(28)(CdBr)(2)](2-) salts in more basic solvents such as acetonitrile and DMSO, respectively. The hydride nature of both [H(2)Ni(22)(C(2))(4)(CO)(28)(CdBr)(2)](2-) and [HNi(22)(C(2))(4)(CO)(28)(CdBr)(2)](3-) has been directly proved by (1)H NMR spectroscopy. Their resonances are very broad under all experimental conditions and their chemical shift greatly depends on solvent as well as temperature. Observation of the hydride resonances in [H(4-n)Ni(22)(C(2))(4)(CO)(28)(CdBr)(2)](n-) (n = 2, 3) makes these clusters a case study of the phenomena behind the loss of any NMR signal in higher-nuclearity metal carbonyl cluster anions (MCCA). In the attempt to obtain a better insight on this experimental spectroscopic behaviour, solutions of [NMe(4)](3)[HNi(22)(C(2))(4)(CO)(28)(CdBr)(2)] have been investigated by dynamic light scattering (DLS) at various concentrations. The DLS experiments point out the presence in solution of a distribution of particles with nominal hydrodynamic diameters enormously greater than those of the free cluster ions resulting, probably, from aggregation in solution. This could formally justify the observed NMR behaviour, even if the present observations are preliminary and their quantitative assessment requires further systematic studies on MCCA aggregation in solution.

12.
Chemistry ; 14(6): 1924-34, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18080263

RESUMEN

Reaction of the [Ni(9)C(CO)(17)](2-) dianion with CdCl(2)2.5 H(2)O in THF affords the novel bimetallic Ni--Cd carbide carbonyl clusters [H(6-n)Ni(30)C(4)(CO)(34)(micro(5)-CdCl)(2)](n-) (n=3-6), which undergo several protonation-deprotonation equilibria in solution depending on the basicity of the solvent or upon addition of acids or bases. Although the occurrence in solution of these equilibria complicates the pertinent electrochemical studies on their electron-transfer activity, they clearly indicate that the clusters [H(6-n)Ni(30)C(4)(CO)(34)(micro(5)-CdCl)(2)](n-) (n=3-6), as well as the structurally related [H(6-n)Ni(34)C(4)(CO)(38)](n-) (n=4-6), undergo reversible or partially reversible redox processes and provide circumstantial and unambiguous evidence for the presence of hydrides for n=3, 4 and 5. Three of the [H(6-n)Ni(30)C(4)(CO)(34)(micro(5)-CdCl)(2)](n-) anions (n=4-6) have been structurally characterized in their [NMe(3)(CH(2)Ph)](4)[H(2)Ni(30)C(4)(CO)(34)(CdCl)(2)]2 COMe(2), [NEt(4)](5)[HNi(30)C(4)(CO)(34)(CdCl)(2)]2 MeCN and [NMe(4)](6)[Ni(30)C(4)(CO)(34)(CdCl)(2)]6 MeCN salts, respectively. All three anions display almost identical geometries and bonding parameters, probably because charge effects are minimized by delocalization over such a large metal carbonyl anion. Moreover, the Ni(30)C(4) core in these Ni-Cd carbide clusters is identical within experimental error to those present in the [HNi(34)C(4)(CO)(38)](5-) and [Ni(35)C(4)(CO)(39)](6-) species, suggesting that the stepwise assembly of their nickel carbide cores may represent a general pathway of growth of nickel polycarbide clusters. The fact that the [H(6-n)Ni(30)C(4)(CO)(34)(micro(5)-CdCl)(2)](n-)(n=4-6) anions display two valence electrons more than the structurally related [H(6-n)Ni(34)C(4)(CO)(38)](n-) (n=4-6) species has been rationalized by extended Hückel molecular orbital (EHMO) analysis.

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