Tuning the Sensing Properties of N and S Co-Doped Carbon Dots for Colorimetric Detection of Copper and Cobalt in Water.

In this study, nitrogen and sulfur co-doped carbon dots (NS-CDs) were investigated for the detection of heavy metals in water through absorption-based colorimetric response. NS-CDs were synthesized by a simple one-pot hydrothermal method and characterized by TEM, STEM-coupled with energy dispersive X-ray analysis, NMR, and IR spectroscopy. Addition of Cu(II) ions to NS-CD aqueous solutions gave origin to a distinct absorption band at 660 nm which was attributed to the formation of cuprammonium complexes through coordination with amino functional groups of NS-CDs. Absorbance increased linearly with Cu(II) concentration in the range 1-100 µM and enabled a limit of detection of 200 nM. No response was observed with the other tested metals, including Fe(III) which, however, appreciably decreased sensitivity to copper. Increase of pH of the NS-CD solution up to 9.5 greatly reduced this interference effect and enhanced the response to Cu(II), thus confirming the different nature of the two interactions. In addition, a concurrent response to Co(II) appeared in a different spectral region, thus suggesting the possibility of dual-species multiple sensitivity. The present method neither requires any other reagents nor any previous assay treatment and thus can be a promising candidate for low-cost monitoring of copper onsite and by unskilled personnel.

Influence of Atmospheric Cold Plasma Exposure on Naturally Present Fungal Spores and Physicochemical Characteristics of Sundried Tomatoes (Solanum lycopersicum L.).

This research aimed to evaluate the impact of atmospheric cold plasma (ACP) treatment on the fungal spores naturally present in sundried tomatoes, as well as their influence on the physico-chemical properties and antioxidant activity. ACP was performed with a Surface Dielectric Barrier Discharge (SDBD), applying 6 kV at 23 kHz and exposure times up to 30 min. The results showed a significant reduction of mesophilic aerobic bacteria population and of filamentous fungi after the longer ACP exposure. In particular, the effect of the treatment was assessed on Aspergillus rugulovalvus (as sensible strain) and Aspergillus niger (as resistant strain). The germination of the spores was observed to be reliant on the species, with nearly 88% and 32% of non-germinated spores for A. rugulovalvus and A. niger, respectively. Fluorescence probes revealed that ACP affects spore viability promoting strong damage to the wall and cellular membrane. For the first time, the sporicidal effect of ACP against A. rugulovalvus is reported. Physicochemical parameters of sundried tomatoes such as pH and water activity (aw) were not affected by the ACP treatment; on the contrary, the antioxidant activity was not affected while the lycopene content was significantly increased with the increase in ACP exposure time (p ≤ 0.05) probably due to increased extractability.

Effect of the Distillation Time on the Chemical Composition, Antioxidant Potential and Antimicrobial Activity of Essential Oils from Different Cannabis sativa L. Cultivars.

Within the unavoidable variability of various origins in the characteristics of essential oils, the aim of this study was to evaluate the effect of the distillation time on the chemical composition and biological activity of Cannabis sativa essential oils (EOs). The dry inflorescences came from Carmagnola, Kompolti, Futura 75, Gran Sasso Kush and Carmagnola Lemon varieties from Abruzzo region (Central Italy), the last two being new cultivar here described for the first time. EOs were collected at 2 h and 4 h of distillation; GC/MS technique was applied to characterize their volatile fraction. The EOs were evaluated for total polyphenol content (TPC), antioxidant capacity (AOC) and antimicrobial activity against food-borne pathogens and spoilage bacteria. The time of distillation particularly influenced EOs chemical composition, extracting more or less terpenic components, but generally enriching with minor sesquiterpenes and cannabidiol. A logical response in ratio of time was observed for antioxidant potential, being the essential oils at 4 h of distillation more active than those distilled for 2 h, and particularly Futura 75. Conversely, except for Futura 75, the effect of time on the antimicrobial activity was variable and requires further investigations; nevertheless, the inhibitory activity of all EOs against Pseudomonas fluorescens P34 was an interesting result.

Characterization of Coffee Silver Skin as Potential Food-Safe Ingredient.

By-products from the coffee industry are produced in large amounts each year. Among other wastes, coffee silver skin (CSS) is highly available and more stable due to its lower content of water. This research aimed to characterize coffee silver skin composition and evidence its potentiality for use as a food-safe ingredient in new formulations. Results showed an average total dietary fiber content of 50% but with a higher ratio for insoluble than soluble fiber. A high content of total phenolic compounds, chlorogenic acid, caffeine, and caffeic acid was found and correlated with the high measured antioxidant capacity. Moreover, minerals (e.g., calcium, magnesium, phosphorous, potassium, copper, iron, manganese) important for human wellbeing were found at a high level in CSS, while toxic minerals (e.g., nickel) were found at low levels. In conclusion, coffee silver skin could have an advantageous role for the recovery of valuable compounds and as a potential food-safe ingredient.

In vitro antioxidant and antimicrobial activity of Cannabis sativa L. cv 'Futura 75' essential oil.

In the present work, Cannabis sativa L. cv Futura 75 inflorescences, cultivated in the Abruzzo territory, were characterized for their volatile fraction through SPME-GC-MS. In addition, the essential oil extracted from these inflorescences was investigated for the antioxidant potentialities and for the terpenic profile. The antibacterial activity of hemp essential oil (HEO) against some pathogenic and spoilage microorganisms isolated from food was also evaluated by determining the minimal inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The results showed significant antioxidant capacity (DPPH: 63.38 ± 0.08 mg TE/g HEO; FRAP: 438.52 ± 6.92 mg TE/g HEO) alongside good antibacterial activity against Gram-positive bacteria such as S. aureus and L. monocytogenes (MIC 1.25-5 µL/mL). The results obtained suggest that hemp essential oil can inhibit or reduce bacterial growth, also exerting antioxidant activity, and therefore it can find an advantageous application in the food processing field.

Chemical Composition and Antioxidant Activity of Thyme, Hemp and Coriander Extracts: A Comparison Study of Maceration, Soxhlet, UAE and RSLDE Techniques.

Appropriate and standardized techniques for the extraction of secondary metabolites with interesting biological activity from plants are required. In this work, a comparison of different conventional and unconventional extraction techniques (maceration-M, Soxhlet-S, ultrasound assisted extraction-UAE, and rapid solid-liquid dynamic extraction-RSLDE) was investigated. Bioactive compounds were extracted from Thymus vulgaris L. (thyme), Cannabis sativa L. (industrial hemp) and Coriandrum sativum L. (coriander) and chemically characterized for their volatile fraction and polyphenolic content by means of gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography-ultraviolet (HPLC-UV). Linalool (48.19%, RSLDE) and carvacrol (21.30%, M) for thyme, caryophyllene (54.78%, S) and humulene (14.13%, S) for hemp, and linalool (84.16%, RSLDE) for coriander seeds were the main compounds among terpenes, while thyme was the richest source of polyphenols with rosmarinic acid (51.7 mg/g dry extract-S), apigenin (7.6 mg/g dry extract-S), and luteolin (4.1 mg/g dry extract-UAE) being the most abundant. In order to shed light on their potential as natural food preservatives, the biological activity of the extracts was assessed in terms of antioxidant activity (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid-ABTS˙+, ferric reducing antioxidant power-FRAP, 2,2-diphenyl-1-picrylhydrazyl-DPPH˙ assays) and phenolic content (Folin-Ciocâlteu method). For thyme, Soxhlet extracts showed best performances in FRAP and ABTS˙+ assays (74 mg TE/g dry extract and 134 mg TE/g dry extract, respectively), while Soxhlet and RSLDE extracts recorded similar activity in DPPH˙ (107-109 mg TE/g dry extract). For hemp and coriander, indeed, RSLDE extracts accounted for higher antioxidant activity as evidenced by FRAP (80 mg TE/g dry extract and 18 mg TE/g dry extract, respectively) and ABTS˙+ (557 mg TE/g dry extract and 48 mg TE/g dry extract, respectively) assays. With respect to DPPH˙, the best results were observed for UAE extracts (45 mg TE/g dry extract and 220 mg TE/g dry extract, respectively). Our findings suggest that all the investigated techniques are valid extraction methods to retain bioactive compounds and preserve their activity for application in food and pharmaceutical formulations. Among them, the innovative RSLDE stands out for the slightly higher antioxidant performances of the extracts, coupled with the facility of use and standardization of the extraction process.

Identification of Cannabis sativa L. (hemp) Retailers by Means of Multivariate Analysis of Cannabinoids.

In this work, the concentration of nine cannabinoids, six neutral cannabinoids (THC, CBD, CBC, CBG, CBN and CBDV) and three acidic cannabinoids (THCA CBGA and CBDA), was used to identify the Italian retailers of Cannabis sativa L. (hemp), reinforcing the idea that the practice of categorizing hemp samples only using THC and CBD is inadequate. A high-performance liquid chromatography/high-resolution mass spectrometry (HPLC-MS/MS) method was developed for screening and simultaneously analyzing the nine cannabinoids in 161 hemp samples sold by four retailers located in different Italian cities. The hemp samples dataset was analyzed by univariate and multivariate analysis with the aim to identify the hemp retailers without any other information on the hemp samples like Cannabis strains, seeds, soil and cultivation characteristics, geographical origin, product storage, etc. The univariate analysis highlighted that the hemp samples could not be differentiated by using any of the nine cannabinoids analyzed. To evaluate the real efficiency of the discrimination among the four hemp retailers a partial least squares discriminant analysis (PLS-DA) was applied. The PLS-DA results showed a very good discrimination between the four hemp retailers with an explained variance of 100% and low classification errors in both calibration (5%) and cross validation (6%). A total of 92% of the hemp samples were correctly classified by the cannabinoid variables in both fitting and cross validation. This work contributed to show that an analytical method coupled with multivariate analysis can be used as a powerful tool for forensic purposes.

ß-Arylethynyl substituted silver corrole complexes.

Silver corrolates are attractive compounds from both practical and theoretical points of view. Indeed, they play a key role in peripheral functionalization reactions occurring at the macrocycle, enabling high-yield and regioselective group insertions useful to further elaborate the molecular skeleton. In parallel, the Janus innocent or noninnocent behavior of the corrole ligand in these complexes makes their description particularly challenging. Herein, we report properties for a series of silver 3,17-disubstituted triarylcorrole complexes with various functionalities (halogens or different phenylethynyl units) that deeply affect the electron density in the macrocyclic ligand, with obvious repercussions on the observed spectral characteristics. The compounds were obtained in yields of 54-92% by applying the Stille coupling reaction with the appropriate tributylethynyl stannane. Among the complexes prepared was a derivative bearing two terminal acetylenic units which opens the way to "click" reactions for new corrole-based architectures. This corrole was structurally characterized by single crystal X-ray crystallography. The addition of substituted ethynyl groups resulted in red-shifts of the electronic absorption spectra, the largest of which was observed for the compound with two ß-NO2-Ph-C[triple bond, length as m-dash]C substituents. The remarkable influence of the NO2 groups on the electron density of this macrocycle was further demonstrated by electrochemical measurements, where an easier reduction of this complex derivative was observed as compared to the others. DFT calculations showed full delocalization over the entire p-nitrophenylethynyl unit of 5, largely affecting orbital distributions and the corresponding electronic absorptions. Although a variation of the ß-substituents dramatically modifies the Soret- and Q-band positions towards lower energies for all the examined complexes, the saddling of the macrocycle resulting from functionalization is only moderate. The collected results suggest the description of these compounds as AgIII-corrolate3-, a metallocorrole with an innocent macrocyclic ligand.

Characterization of Essential Oils Obtained from Abruzzo Autochthonous Plants: Antioxidant and Antimicrobial Activities Assessment for Food Application.

In the present study, the essential oils (EOs) of some officinal plants from Abruzzo territory (Italy) were evaluated for their antimicrobial and antioxidant activities and their volatile fraction chemical characterization. The EOs were extracted from Rosmarinus officinalis, Origanum vulgare, Salvia officinalis, Mentha piperita, Allium sativum, Foeniculum vulgare, Satureja montana, Thymus vulgaris and Coriandrum sativum seeds. The antimicrobial activity was screened against thirteen Gram-positive and Gram-negative strains to determine the Minimal Inhibitory Concentration (MIC). The total phenolic content (TPC) and the antioxidant capacity (AOC) were assessed by means of Folin-Ciocâlteu method, and Trolox Equivalent Antioxidant Capacity with 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (TEAC/ABTS), Ferric Reducing Antioxidant Power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays respectively. Among the nine EOs tested, T. vulgaris, S. montana, O. vulgare and C. sativum EOs showed MIC values ranging from 0.625 to 5 µL/mL. The AOC and TPC results for these species were also interesting. The major components for these EOs were thymol for T. vulgaris (44%) and O. vulgare (40%), linalool (77%) for C. sativum, and carvacrol for S. montana (54%). The results allowed the study to establish that these EOs are good candidates for potential application as biopreservatives in foods and/or food manufacture environments.

Role of reduced expression of SMAD4 in papillary thyroid carcinoma.

It has been demonstrated that transforming growth factor-ß (TGFß) and other members of TGFß superfamily play an important role in thyroid proliferative diseases. The deficiencies of SMAD4 are responsible to accelerate the malignant progression of neoplastic lesions in several types of tumors. Therefore, the objective of the present study was to determine the functional role of reduced expression of SMAD4 in human papillary thyroid carcinogenesis. For this purpose, we examined the TGFß response in two cell lines, TPC-1 and BCPAP. Our data demonstrated for the first time that these cells showed a strong reduction in the level of SMAD4 protein, which was responsible for an alteration of TGFß signaling and for some of the TGFß-mediated biological effects. The overexpression of SMAD4, restoring TGFß transduction, determined a significant increase of antiproliferative response to TGFß, and reduced the invasive behavior of these cells. Therefore, our data indicated that reduction of SMAD4 may play a significant role in thyroid carcinogenesis.

The Golgi alpha-1,6 mannosyltransferase KlOch1p of Kluyveromyces lactis is required for Ca2+/calmodulin-based signaling and for proper mitochondrial functionality.

BACKGROUND: Protein N-glycosylation is a relevant metabolic pathway in eukaryotes and plays key roles in cell processes. In yeasts, outer chain branching is initiated in the Golgi apparatus by the alpha-1,6-mannosyltransferase Och1p. RESULTS: Here we report that, in Kluyveromyces lactis, this glycosyltransferase is also required to maintain functional mitochondria and calcium homeostasis. Cells carrying a mutation in KlOCH1 gene showed altered mitochondrial morphology, increased accumulation of ROS and reduced expression of calcium signalling genes such as calmodulin and calcineurin. Intracellular calcium concentration was also reduced in the mutant cells with respect to the wild type counterparts.Phenotypes that occur in cells lacking the alpha-1,6-mannosyltransferase, including oxidative stress and impaired mitochondria functionality, were suppressed by increased dosage of KlCmd1p. This, in turn, acts through the action of calcineurin. CONCLUSIONS: Proper functioning of the alpha-1,6-mannosyltransferase in the N-glycosylation pathway of K. lactis is required for maintaining normal calcium homeostasis; this is necessary for physiological mitochondria dynamics and functionality.

Dead blood under my skin.

The diagnostic attitude of western physicians toward migrants' complaints is often an unstable balance between the obstinate search for exotic tropical diseases and the overappreciation of the cultural dimensions of symptoms. Such attitude may divert attention from organic diseases. The careful assessment of all levels of possible misunderstandings (prelinguistic, linguistic, metalinguistic, cultural, and metacultural) may help the physician to discriminate between illness and disease. The long and difficult itinerary leading to the correct diagnosis of congenital myopathy in a migrant from Senegal is described, together with the barriers encountered by the caring staff.

Functional trajectories during hospitalization: a prognostic sign for elderly patients.

BACKGROUND: Clinicians have used measurements of pathological conditions and functional status to capture the heterogeneity of older individuals for prognostic purposes. However, the literature pays low attention to physical functional changes. METHODS: A retrospective cohort study to investigate the association between functional changes during hospitalization and 3-month mortality. A total of 1,119 acutely ill elderly patients admitted to four beds arranged like a high-dependency area in a geriatric unit (mean age 80.6 +/- 7.8 years) were subdivided into four groups according to degree of functional decline at admission in comparison with the premorbid level and ability or inability to regain function at discharge: with moderate loss, able to regain (group a) and unable to regain function (group b); and with severe loss, able to regain (group c) and unable to regain function (group d) during hospitalization. Age, gender, cognitive and functional status (basic activities of daily living -[BADL]), serum albumin, Acute Physiology Score, Acute Physiology and Chronic Health Evaluation II score, comorbid conditions, number of drugs, and length of stay were collected. RESULTS: Total 3-month mortality was 17.9%. Mortality rate was 10.7%, 17.6%, 14.5%, and 36.7% in groups a, b, c, and d, respectively. In three different multivariate Cox models including BADLs before admission, at admission, and at discharge, inability to regain function during hospitalization was an independent factor associated with 3-month mortality. CONCLUSIONS: In acutely ill elderly patients, lack of function regain during hospitalization is associated with higher mortality rate at 3 months, compared with those capable to regain the baseline functional status.

Hyperglycemia as a predictor of in-hospital mortality in elderly patients without diabetes mellitus admitted to a sub-intensive care unit.

OBJECTIVES: To investigate the association between hyperglycemia and in-hospital and 45-day mortality in acutely ill elderly patients. DESIGN: Retrospective cohort. SETTING: Hospital medical patients admitted to a sub-intensive care unit (sub-ICU) for elderly patients, which is a level of care between ordinary wards and intensive care. PARTICIPANTS: One thousand two hundred twenty-nine patients (mean age 79.6+/-8.4) admitted to the sub-ICU from January 2003 to January 2006. Forty patients with acute myocardial infarction and 34 patients with extreme fasting glucose values (<60 or >500 mg/dL) were excluded. Eight hundred twenty-two patients without a history of diabetes mellitus (DM) and 333 patients with a diagnosis of DM were selected and subdivided into three categories according to serum fasting blood glucose: 60 to 126 mg/dL (Group A), 127 to 180 mg/dL (Group B), and 181 to 500 mg/dL (Group C). MEASUREMENTS: Age, sex, mental and functional status, Acute Physiology Score, comorbid conditions, serum albumin, serum cholesterol, fasting serum glucose, and length of stay. In-hospital mortality was the primary outcome, and 45-day mortality was the secondary outcome. RESULTS: Total in-hospital mortality was 14.5%. In patients with and without DM, mortality was 8.8% and 11.3%, respectively, in Group A; 13.6% and 17.3% in Group B, and 12.6% and 34.3% in Group C. After controlling for confounders, newly recognized hyperglycemia (>181 mg/dL) was independently associated with in-hospital mortality (adjusted odds ratio=2.7, 95% confidence interval=1.6-4.8). Forty-five-day mortality in newly recognized hyperglycemic patients was 17.5%, 25.7%, and 42% in Groups A, B, and C, respectively, whereas it was 21.2% in patients with DM. CONCLUSION: In elderly patients, newly recognized hyperglycemia was associated with a higher mortality rate than in those with a prior history of DM. These data suggest that further randomized clinical trials are needed to assess the efficacy and the risk of a target glucose of greater than 180 mg/dL.

Insulin resistance impairs rapid virologic response in HIV/hepatitis C virus coinfected patients on peginterferon-alfa-2a.

OBJECTIVES: To investigate the association between insulin resistance and rapid virologic response. DESIGN: All consecutive HIV/hepatitis C virus coinfected patients who started peg-interferon alpha-2a (180 microg/week) and ribavirin 1000-1200 mg/day were analysed. METHODS: Insulin resistance was defined according to the homeostasis model of assessment-insulin resistance calculated as fasting insulin (mIU/l) x fasting glucose (mmol/l)/22.5. Rapid virologic response was defined as testing negative for hepatitis C virus-RNA after 4 weeks of therapy. Fasting levels of insulin and glucose in plasma were measured in all patients on the first day of treatment. Hepatitis C virus-RNA was determined by quantitative PCR assay (version 3.0). Hepatitis C virus-RNA was measured by qualitative PCR assay (COBAS 2.0) after 4 weeks of treatment. RESULTS: Seventy-four HIV/hepatitis C virus coinfected patients were enrolled [mean age 41.7 years (SD 5.3), 61 men, 54.1% with advanced fibrosis (F3-4 according to METAVIR classification), 52.4% with infection by hepatitis C virus genotype 1 or 4]. Rapid virologic response was reached by 30 subjects. In the multivariate analysis the independent predictors of rapid virologic response were: genotype 1 or 4 [adjusted odds ratio 0.18 (0.06-0.55)], hepatitis C virus-RNA < 400.000 UI/ml [adjusted odds ratio 0.229 (0.09-0.92)] and homeostasis model of assessment-insulin resistance more than 3.00 [adjusted odds ratio 0.1 (0.05-0.6)]. CONCLUSION: The homeostasis model of assessment-insulin resistance score should be evaluated and possibly corrected before starting anti-hepatitis C virus therapy.

Subintensive care unit for the elderly: a new model of care for critically ill frail elderly medical patients.

OBJECTIVE: An increasing number of elderly patients are admitted to the hospital for critical diseases and the gap between supply and demand of intensive care resources is a growing problem. To meet this challenge, 4 beds in a 24-bed acute care for the elderly (ACE) medical unit were dedicated to a subintensive care unit (SICU). Severely ill elderly medical patients, requiring a higher level of care than provided in ordinary wards, are admitted. The aim of the study was to describe the characteristics of the setting and to discuss its usefulness based on data obtained after the first period of implementation. METHODS: This article describes the development, management, economics and patient characteristics of the SICU. Patient care combines the ACE model with a highly specialised medical care. Patients admitted to the SICU are compared with patients treated in the ordinary ACE unit before the SICU opened. All patients received a multidimensional evaluation, including demographics, main diagnosis, number of chronic somatic diseases, Charlson index, APACHE II score, APACHE-APS subscore, number of currently administered drugs, serum albumin, cognitive status (Mini-Mental State Examination), depression (Geriatric Depression Scale) and functional status (basic and instrumental activities of daily living). Ward physicians performed assessment and collection of data. RESULTS: During the first 16 months, 489 patients were admitted, 401 according to the selection criteria (60 +/- years and APACHE II score > or =5 and/or APACHE-APS score > or =3). Mean age was 78.1 years, mean APACHE II score 14.5 (moderate severity) and non-invasive mechanical ventilation was received by 87 (21.7%). The most common diagnoses were respiratory failure, cardiac disease and stroke. Mean length of stay in the SICU was 61.8 h, and 6.0 days in the hospital. Compared with ACE-unit patients admitted during 2002 (n=1380), SICU patients were obviously more seriously ill (APACHE II score 14.5 vs 6.7). When comparing patients of same illness severity (APACHE-APS score > or =3) (n=125), patients treated in the SICU had lower in-hospital mortality than those treated in the ordinary ACE ward (12.5 vs 19.2%). Only a few patients (3.5%) were transferred to the intensive care unit as a consequence of increased severity of illness. CONCLUSIONS: The SICU is an innovative method to treat frail elderly patients with more severe conditions. Low hospital mortality compared with that of severe patients in the ACE unit supports the usefulness of this model. It could be implemented in medical units of large hospitals in order to give optimal care and advanced interventions to the frail elderly and to avoid intensive care unit overcrowding.

Mechanism of the palladium-catalyzed metal-carbon bond formation. A dual pathway for the transmetalation step.

The mechanism of the transmetalation step in the metal-carbon bond-formation process catalyzed by palladium complexes has been studied by spectroscopic and kinetic methods. The reaction of properly designed model complexes [structure: see text], resulting from oxidative addition of a Mo-I moiety to a palladium center, with aryltributyltinacetylides Bu(3)Sn-C [triple bond] C-(p-XC(6)H(4)) (11a, X = H; 11b, X = Cl) yields the products of transmetalation [structure: see text] (5a,b). The reaction, which shows a strong dependence on the nature of the phosphine ligand PR(3) (Ph > Bu > Me) and less so on the nature of the p-substituent X group, proceeds through two competing pathways, depending on the initial concentration of substrate. At high [3] (approximately equal to 10(-2) M), the transmetalation proceeds through an intermediate species (12) formed by the interaction of complex 3 with 11a. This associative complex accumulates in the presence of added PPh(3) and has been characterized spectroscopically. At low [3] (approximately equal to 10(-4) M), the reaction rate shows an inverse dependence on the concentration of the complex. This is due to the formation of a solvent-coordinate species (13), in which PPh(3) has been substituted by a dimethylformamide (DMF) molecule, as shown by UV-vis and (31)P NMR spectroscopy. Values of k(obs) depend on the concentration and nature of the aryltributyltinacetylides, in agreement with the existence of a kinetically detectable intermediate. A dimeric iodide bridged complex [structure: see text](14) has been obtained during attempts at isolating 13, which changes quantitatively into 13 upon dissolution in DMF and reacts with 11a to give the transmetalation product.