The rapid assembly of an elliptical galaxy of 400 billion solar masses at a redshift of 2.3.

Stellar archaeology shows that massive elliptical galaxies formed rapidly about ten billion years ago with star-formation rates of above several hundred solar masses per year. Their progenitors are probably the submillimetre bright galaxies at redshifts z greater than 2. Although the mean molecular gas mass (5 × 10(10) solar masses) of the submillimetre bright galaxies can explain the formation of typical elliptical galaxies, it is inadequate to form elliptical galaxies that already have stellar masses above 2 × 10(11) solar masses at z ≈ 2. Here we report multi-wavelength high-resolution observations of a rare merger of two massive submillimetre bright galaxies at z = 2.3. The system is seen to be forming stars at a rate of 2,000 solar masses per year. The star-formation efficiency is an order of magnitude greater than that of normal galaxies, so the gas reservoir will be exhausted and star formation will be quenched in only around 200 million years. At a projected separation of 19 kiloparsecs, the two massive starbursts are about to merge and form a passive elliptical galaxy with a stellar mass of about 4 × 10(11) solar masses. We conclude that gas-rich major galaxy mergers with intense star formation can form the most massive elliptical galaxies by z ≈ 1.5.

A dust-obscured massive maximum-starburst galaxy at a redshift of 6.34.

Massive present-day early-type (elliptical and lenticular) galaxies probably gained the bulk of their stellar mass and heavy elements through intense, dust-enshrouded starbursts--that is, increased rates of star formation--in the most massive dark-matter haloes at early epochs. However, it remains unknown how soon after the Big Bang massive starburst progenitors exist. The measured redshift (z) distribution of dusty, massive starbursts has long been suspected to be biased low in z owing to selection effects, as confirmed by recent findings of systems with redshifts as high as ~5 (refs 2-4). Here we report the identification of a massive starburst galaxy at z = 6.34 through a submillimetre colour-selection technique. We unambiguously determined the redshift from a suite of molecular and atomic fine-structure cooling lines. These measurements reveal a hundred billion solar masses of highly excited, chemically evolved interstellar medium in this galaxy, which constitutes at least 40 per cent of the baryonic mass. A 'maximum starburst' converts the gas into stars at a rate more than 2,000 times that of the Milky Way, a rate among the highest observed at any epoch. Despite the overall downturn in cosmic star formation towards the highest redshifts, it seems that environments mature enough to form the most massive, intense starbursts existed at least as early as 880 million years after the Big Bang.

Histopathology of the muscle in rheumatic diseases.

The presence of muscular symptoms is common in rheumatological clinical practice, but often the differential diagnosis between muscular involvement in connective tissue diseases, vasculitis and drug-induced myopathy may be difficult. In addition to clinical assessment, laboratory analysis and instrumental examinations, muscle biopsy may help to clarify the diagnosis in patients with muscular involvement. The purpose of this review is to provide a critical analysis of the current medical literature on muscular histopathology, to help clinicians to identify when to perform muscular biopsy and to provide a practical guide to a better understanding of the pathology report. Moreover, we provide an overview of the muscular involvement and the most common histopathological findings in rheumatic diseases.

The use of rituximab in idiopathic inflammatory myopathies: description of a monocentric cohort and review of the literature.

Rituximab (RTX), a chimeric monoclonal antibody targeted against CD20, has been used to treat refractory inflammatory myopathies (IIM). The primary objective of this study was to retrospectively assess the efficacy of RTX in reducing disease activity in patients with IIM refractory to conventional therapy. Secondary aim was the evaluation of adverse events (AE) during the treatment period. We examined 26 patients with a diagnosis of IIM, referred to our Rheumatology Unit and treated with RTX for active refractory disease. Patients were treated with RTX 1000 mg i.v., twice, with a 2-week interval. RTX treatment was associated with a significant reduction of creatine kinase (p=0.001) after six months compared to the baseline, an improved muscular strength measured with MMT8 (p<0.001) and a reduction of the extramuscular activity of the disease measured with MYOACT (p<0.001). In particular, RTX improved DM skin rash, arthritis and pulmonary manifestations. Autoantibody positivity (in particular antisynthetase, anti- SRP and antiRo/SSA), and a disease duration <36 months at the moment of the treatment are associated with a better response rate. Treatment with RTX was also associated with a reduction of the mean daily dose of steroids needed to control disease activity (p=0.002). Our results have confirmed that RTX is efficacious in the treatment of refractory IIM. Ad hoc controlled trials are needed to better clarify the specific subset of patients who may better respond to the treatment and the optimal therapeutic schedule.

High molecular gas fractions in normal massive star-forming galaxies in the young Universe.

Stars form from cold molecular interstellar gas. As this is relatively rare in the local Universe, galaxies like the Milky Way form only a few new stars per year. Typical massive galaxies in the distant Universe formed stars an order of magnitude more rapidly. Unless star formation was significantly more efficient, this difference suggests that young galaxies were much more molecular-gas rich. Molecular gas observations in the distant Universe have so far largely been restricted to very luminous, rare objects, including mergers and quasars, and accordingly we do not yet have a clear idea about the gas content of more normal (albeit massive) galaxies. Here we report the results of a survey of molecular gas in samples of typical massive-star-forming galaxies at mean redshifts of about 1.2 and 2.3, when the Universe was respectively 40% and 24% of its current age. Our measurements reveal that distant star forming galaxies were indeed gas rich, and that the star formation efficiency is not strongly dependent on cosmic epoch. The average fraction of cold gas relative to total galaxy baryonic mass at z = 2.3 and z = 1.2 is respectively about 44% and 34%, three to ten times higher than in today's massive spiral galaxies. The slow decrease between z approximately 2 and z approximately 1 probably requires a mechanism of semi-continuous replenishment of fresh gas to the young galaxies.

Intense star formation within resolved compact regions in a galaxy at z = 2.3.

Massive galaxies in the early Universe have been shown to be forming stars at surprisingly high rates. Prominent examples are dust-obscured galaxies which are luminous when observed at sub-millimetre wavelengths and which may be forming stars at a rate of 1,000 solar masses (M(middle dot in circle)) per year. These intense bursts of star formation are believed to be driven by mergers between gas-rich galaxies. Probing the properties of individual star-forming regions within these galaxies, however, is beyond the spatial resolution and sensitivity of even the largest telescopes at present. Here we report observations of the sub-millimetre galaxy SMMJ2135-0102 at redshift z = 2.3259, which has been gravitationally magnified by a factor of 32 by a massive foreground galaxy cluster lens. This magnification, when combined with high-resolution sub-millimetre imaging, resolves the star-forming regions at a linear scale of only 100 parsecs. We find that the luminosity densities of these star-forming regions are comparable to the dense cores of giant molecular clouds in the local Universe, but they are about a hundred times larger and 10(7) times more luminous. Although vigorously star-forming, the underlying physics of the star-formation processes at z approximately 2 appears to be similar to that seen in local galaxies, although the energetics are unlike anything found in the present-day Universe.

Bone density assessment in a cohort of pediatric patients affected by 22q11DS.

OBJECTIVE: Hypoparathyroidism and hypocalcemia are two of the most frequent clinical characteristics of 22q11-deletion syndrome (22q11DS). The aim of this study was to evaluate bone metabolism and density in a cohort of patients affected by 22q11DS. METHODS: In 8 pediatric patients (mean age 11.5 years; range 7-16.4) affected by 22q11DS, creatinine, albumin, total and ionized calcium, phosphate, 25(OH) vitamin D, parathyroid hormone, osteocalcin, C-terminal telopeptide and interleukin 6 were assessed. Furthermore, bone mineral density (BMD) was determined by dual-energy X-ray absorptiometry procedure. 14 healthy children were considered as controls. RESULTS: Most of the studied subjects were overweight and lacked quality physical activity. 40 % of the subjects had reduced calcium levels in the absence of related clinical symptoms and all patients also had inadequate levels of Vitamin D. The values of L1-L4 BMD were within the reference range in all patients (z score <2). However, after comparing the age-matched indexes of bone mineralization of patients with those of controls, the former had lower bone mineralization indexes than the latter. CONCLUSIONS: In pediatric patients with 22q11DS, an initial and slight bone loss is evident. The incidence of hypocalcemia is underestimated because hypocalcemia is asymptomatic. Several factors contribute to bone impairment in children who still have to achieve bone mass peak. Therefore, we suggest strict monitoring of bone metabolism as well as BMD measurement in patients affected by 22q11DS.

Annular subacute cutaneous lupus erythematosus lesions and polymyositis onset in a patient with primary Sjogren's syndrome: how should this unusual association be classified?

Classification of the wide variety of autoimmune diseases that can occur before or after the onset of Sjögren's syndrome (SS) is currently debated within the conventional SS criteria or as primary SS (pSS) developing autoimmune disease or as 'associated-overlap' with other systemic autoimmune diseases. There is also debate on whether or not to consider annular polycyclic subacute cutaneous lupus erythematosus (SCLE) and annular erythema associated with Sjögren's syndrome (AESS) as a spectrum linked to Ro-SSA and/or La-SSB auto-antibodies (SSA/SSB auto-ab). We present the case of a 55-year-old female patient, with pSS positive for SSA and SSB auto-ab, who developed chronic relapsing polymyositis and atypical annular non-polycyclic SCLE lesions resembling AESS, which seemed to suggest a common spectrum. While a chronic-progressive polymyositis may be generally accepted as a relatively rare myositis complicating pSS, interpretation of annular lesions of non-systemic SCLE in SS patients might actually be underestimated as pSS skin manifestation likely related to SSA/SSB auto-ab.

Extraction and characterization of collagen from the skin of Amazonian freshwater fish pirarucu.

The need to fully exploit fishing resources due to increasing production and consequent waste generation requires research to promote the sustainability of the fishing industry. Fish waste from the industry is responsible for relevant environmental contamination. However, these raw materials contain high amounts of collagen and other biomolecules, being attractive due to their industrial and biotechnological applicability. Thus, to reduce the waste from pirarucu (Arapaima gigas) processing, this study aimed to obtain collagen from pirarucu skin tissue. The extraction process used 0.05 M sodium hydroxide, 10% butyl alcohol, and 0.5 M acetic acid, with extraction temperature of 20°C. The obtained yield was 27.8%, and through sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), it was determined that the collagen obtained was type I. This study showed that collagen solubility was highest at pH 3 and the lowest solubility was at concentrations of 3% sodium chloride. The denaturation temperature of collagen was 38.1°C, and its intact molecular structure was observed using the Fourier transform infrared spectrophotometry technique with an absorption radius of 1. The results showed that it was possible to obtain collagen from pirarucu skin at 20°C, which has the typical characteristics of commercial type I collagen. In conclusion, the procedures used may be considered to be an interesting alternative for collagen extraction, a new product obtained from the processing of fish waste.

[Long term outcome of treatment of diffuse proliferative glomerulonephritis with pulse steroids and short course pulse cyclophosphamide]. / Outcome a lungo termine di pazienti con glomerulonefrite lupica proliferativa diffusa trattati con boli di steroidi e un breve ciclo di ciclofosfamide.

OBJECTIVES: To evaluate the long- term outcome of a group of systemic lupus erythematosus (SLE) patients with diffuse proliferative glomerulonephritis (DPGN) treated with pulse steroids and a short course of pulse cyclophosphamide (Cyc) in order to find out baseline predictor variables of disease outcome at the end of the follow-up. METHODS: Female SLE patients fulfilling ACR criteria with active DPGN treated with pulse steroids and pulse Cyc were enrolled in the study and retrospectively analyzed with particular interest to renal flares and poor renal outcome at the end of follow- up as outcome measures. RESULTS: 30 female patients with DPGN were included, of these 20 (66,7%) patients are actually in follow-up at our unit, 4 (13.3%) died and 6 (20%) were lost during the follow-up. Fourteen patients (46.6%) presented at least one renal flare (RF) during the follow up for a total of 21 flares. At our last observation, 18 (60%) presented a good renal outcome while 12 (40%) had a poor outcome. Lower age at kidney biopsy resulted an important prognostic factor for the occurrence of both RF and poor long- term renal outcome; additionally, a poor renal outcome resulted significantly correlated with an inadequate response at the end of the protocol and with the number of renal flares after remission. CONCLUSIONS: These data suggest that, in general, a short course therapy with Cyc might be effective in controlling disease activity but demonstrated high rate of RF and poor renal outcome over time; however, this protocol might represent an effective therapeutic strategy in a subgroup of patients with specific epidemiological and clinical characteristics and suggest the possibility of tailoring immunosuppressive therapy on the basis of prognostic factor at baseline.

Cast iron street furniture: A historical review.

The term "street furniture" indicates objects mostly made of cast iron alloys and aimed to improve the quality of life in urban settlements, such as street lamps, fountains and gazebos. These objects are often ancient and relevant as cultural heritage. Despite the constant presence of street furniture in urban settlements, studies of its evolution along centuries are limited. Since functional aspects have been often considered prevalent against artistic and historical values, many objects have been considered obsolete, thus replaced or re-melted. Street furniture rarely received attention by scholars, and studies on this topic have been often incomplete. This study reviews the history of street furniture made of cast iron (CI street furniture), first examining the reasons behind the choice of this material, closely related to its diffusion during the First Industrial Revolution. The review discusses the relationship between CI street furniture and cultural heritage based on artistic, aesthetic and ethical issues, also examining historical catalogs. The development of CI street furniture in United Kingdom, France and Italy is reported, together with their local aspects. The production technique is discussed and the importance of preservation of CI street furniture is highlighted, emphasizing the need for globally planned interventions in this field.

[Churg-Strauss syndrome: outcome and long-term follow-up of 38 patients from a single Italian centre]. / Caratteristiche clinico-sierologiche e dati di out come di una casistica monocentrica di pazienti affetti da sindrome di Churg-Strauss.

OBJECTIVE: This study was aimed at verifying any potential correlation between anti-myeloperoxidase antineutrophil cytoplasmic antibodies (ANCA-MPO) and clinical features and outcome indices in Churg-Strauss Syndrome (CSS). METHODS: Thirty-eight Churg-Strauss syndrome patients were selected from the medical records of all vasculitis patients attending the Rheumatology and Immunology Unit at the Department of Internal Medicine of the University of Pisa in the decades between 1989 and 2008. Data were analysed retrospectively. Statistical analyses of the results were carried out using the Mann-Whitney test to determine the correlations between the clinical and serological parameters. Qualitative variables were compared using contingency table analysis and Fisher's exact test. RESULTS: ANCA-MPO were detected in15/38 (39%) patients. Positive ANCA status was associated with peripheral neuropathy (p=0.0006), whereas negative ANCA status was associated with lung involvement (p=0.002). Relapses were strongly associated with positive ANCA status (p=0.01) and with an increase in- or a reappearance of ANCA-MPO levels (p=0.006). Finally, ANCA-MPO were significantly associated with neurological damage (p=0.003). CONCLUSIONS: The presence or absence of ANCA-MPO identify different clinical subsets in CSS. Overall, ANCA-MPO appears as a useful tool in the monitoring of CSS and in particular a good predictor of CSS relapses.

Characterization of digestive enzymes from captive Brazilian flounder Paralichthys orbignyanus.

Knowledge of specific enzyme activity, along with animal habits and digestive capacity is essential in formulating an appropriate diet for any species. In this study, we evaluated and characterized the activity of digestive enzymes present in the liver, intestine, and stomach of Paralichthys orbignyanus. The effects of pH and temperature on enzyme activity were also evaluated via the use of specific substrates. The use of specific substrates and inhibitors showed strong evidence of the presence of trypsin (BApNA= 0.51 ± 0.2 mU mg-1), chimotrypsin (SApNA= 2.62 ± 1.8 mU mg-1), and aminopeptidases (Leu-p-Nan =0.9709 ± 0.83 mU mg-1) in the intestine. Optimum pH for the activity of trypsin, chemotrypsin, leucino aminopeptidase, amilase, and pepsin were 9.5, 9.0, 8.0, 7.5, and 3.5, respectively, while optimum temperatures were 50, 50, 50, 40, and 45 °C, respectively. These results provide additional information regarding the biology of Brazilian flounder and can be used as a basis for further studies regarding fish feeding physiology.

Extraction and characterization of collagen from the skin of Amazonian freshwater fish pirarucu

The need to fully exploit fishing resources due to increasing production and consequent waste generation requires research to promote the sustainability of the fishing industry. Fish waste from the industry is responsible for relevant environmental contamination. However, these raw materials contain high amounts of collagen and other biomolecules, being attractive due to their industrial and biotechnological applicability. Thus, to reduce the waste from pirarucu (Arapaima gigas) processing, this study aimed to obtain collagen from pirarucu skin tissue. The extraction process used 0.05 M sodium hydroxide, 10% butyl alcohol, and 0.5 M acetic acid, with extraction temperature of 20°C. The obtained yield was 27.8%, and through sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), it was determined that the collagen obtained was type I. This study showed that collagen solubility was highest at pH 3 and the lowest solubility was at concentrations of 3% sodium chloride. The denaturation temperature of collagen was 38.1°C, and its intact molecular structure was observed using the Fourier transform infrared spectrophotometry technique with an absorption radius of 1. The results showed that it was possible to obtain collagen from pirarucu skin at 20°C, which has the typical characteristics of commercial type I collagen. In conclusion, the procedures used may be considered to be an interesting alternative for collagen extraction, a new product obtained from the processing of fish waste.

ALMA high spatial resolution observations of the dense molecular region of NGC 6302.

CONTEXT: The mechanism behind the shaping of bipolar planetary nebulae is still poorly understood. It is becoming increasingly clear that the main agents must operate at their innermost regions, where a significant equatorial density enhancement should be present and related to the collimation of light and jet launching from the central star preferentially towards the polar directions. Most of the material in this equatorial condensation must be lost during the asymptotic giant branch as stellar wind and later released from the surface of dust grains to the gas phase in molecular form. Accurately tracing the molecule-rich regions of these objects can give valuable insight into the ejection mechanisms themselves. AIMS: We investigate the physical conditions, structure and velocity field of the dense molecular region of the planetary nebula NGC 6302 by means of ALMA band 7 interferometric maps. METHODS: The high spatial resolution of the 12CO and 13CO J=3-2 ALMA data allows for an analysis of the geometry of the ejecta in unprecedented detail. We built a spatio-kinematical model of the molecular region with the software SHAPE and performed detailed non-LTE calculations of excitation and radiative transfer with the shapemol plug-in. RESULTS: We find that the molecular region consists of a massive ring out of which a system of fragments of lobe walls emerge and enclose the base of the lobes visible in the optical. The general properties of this region are in agreement with previous works, although the much greater spatial resolution of the data allows for a very detailed description. We confirm that the mass of the molecular region is 0.1 M⊙. Additionally, we report a previously undetected component at the nebular equator, an inner, younger ring inclined ~60° with respect to the main ring, showing a characteristic radius of 7.5×1016 cm, a mass of 2.7×10-3 M⊙, and a counterpart in optical images of the nebula. This inner ring has the same kinematical age as the northwest optical lobes, implying it was ejected approximately at the same time, hundreds of years after the ejection of the bulk of the molecular ring-like region. We discuss a sequence of events leading to the formation of the molecular and optical nebulae, and briefly speculate on the origin of this intriguing inner ring.

Sub-arcsecond imaging of the water emission in Arp 220.

AIMS: Extragalactic observations of water emission can provide valuable insights into the excitation of the interstellar medium. In particular they allow us to investigate the excitation mechanisms in obscured nuclei, i.e. whether an active galactic nucleus or a starburst dominate. METHODS: We use sub-arcsecond resolution observations to tackle the nature of the water emission in Arp 220. ALMA Band 5 science verification observations of the 183 GHz H2O 313-220 line, in conjunction with new ALMA Band 7 H2O 515-422 data at 325 GHz, and supplementary 22 GHz H2O 616 - 523 VLA observations, are used to better constrain the parameter space in the excitation modelling of the water lines. RESULTS: We detect 183 GHz H2O and 325 GHz water emission towards the two compact nuclei at the center of Arp 220, being brighter in Arp 220 West. The emission at these two frequencies is compared to previous single-dish data and does not show evidence of variability. The 183 and 325 GHz lines show similar spectra and kinematics, but the 22 GHz profile is significantly different in both nuclei due to a blend with an NH3 absorption line. CONCLUSIONS: Our findings suggest that the most likely scenario to cause the observed water emission in Arp 220 is a large number of independent masers originating from numerous star-forming regions.

Functional and isokinetic assessment of muscle strength in patients with idiopathic inflammatory myopathies.

OBJECTIVE: To assess muscle strength in patients with idiopathic inflammatory myopathies (IIM) using neuromuscular scales and isokinetic testing. METHODS: Muscle function was evaluated in 27 IIM patients being followed at the Rheumatology Unit of the University of Pisa using: (i) a modified version of the grading system used to assess Duchenne dystrophy, (ii) the four-stage grading system of Henriksson and Sandstedt, (iii) an isokinetic muscle strength test (Kin Com, Chatanooga) and (iv) the Health Assessment Questionnaire (HAQ). RESULTS: The neuromuscular scales showed normal or only mildly impaired muscle strength in 60% (Duchenne scale) and 80% (Henriksson and Sandstedt scale) of the patients, respectively, whereas isokinetic testing detected moderate to severe reductions in muscle strength in almost 70% of the patients. No correlations were observed between muscle strength and disease activity, therapy, age at evaluation and disease duration. There was a correlation between the results of the HAQ and neuromuscular testing, but not the isokinetic test. CONCLUSIONS: Although less easy and more expensive to administer, isokinetic testing appears to be a more sensitive instrument than the standard neuromuscular tests for assessing muscle function in IIM patients. In particular, it can detect small reductions in muscle strength.

The alexander surgical technique for the treatment of severe burns.

The extensive loss of skin in burned patients is a critical clinical condition, and the choice of an effective technique to cover and protect the damaged area has always been a challenge in the surgical field. Despite its wide clinical use, there is little data in the literature on using the Alexander technique to treat severe burns, while several studies have focused on alternative approaches. The present study aims to evaluate the effectiveness of the Alexander surgical technique on 117 patients with severe burns. The characteristics of the burned patients, factors related to etiology of burns as well as adverse prognostic factors and their incidence in discharged versus deceased patients were also taken into account. Finally, a comparison is made with an alternative surgical procedure described in the literature. Our results show a satisfactory level of survival for patients with severe burns surgically treated with the Alexander technique, accounting for 63% of all clinical cases reported here. This treatment is also less expensive and more rapid than the alternative approach we compared it with. The Alexander technique is a lifesaving method for the treatment of severe burns that provides a satisfactory chance of survival at lower cost than the alternative surgical procedure examined.

Une vaste perte de substance cutanée chez les brûlés détermine un état clinique critique, et le choix d'une technique efficace pour couvrir et protéger les zones détruites a toujours été un challenge chirurgical. Malgré sa large utilisation, il y a peu de références dans la littérature sur l'utilisation de la technique d'Alexander dans le traitement les brûlures graves, alors que différentes études insistent sur d'autres approches. Cette étude a pour but d'évaluer l'efficacité de la technique chirurgicale d'Alexander sur 117 patients présentant des brûlures graves. Les caractéristiques de ces brûlés (étiologie, facteurs pronostiques défavorables et leur incidence sur la sortie de l'hôpital) ont été prises en compte, comme celles des patients décédés. Enfin, la comparaison est faite avec les autres procédés alternatifs chirurgicaux décrits dans la littérature. Nos résultats montrent un taux satisfaisant de survie chez les patients présentant des brûlures graves traitées par la technique d'Alexander: 63% de tous les cas cliniques rassemblés ici. Le traitement est aussi moins cher et plus rapide que dans les techniques alternatives. La technique d'Alexander est une méthode de sauvetage pour le traitement des brûlures graves qui offre une chance satisfaisante de survie à un coût moindre que les autres techniques alternatives.

High spatial resolution imaging of SO and H2CO in AB Auriga: The first SO image in a transitional disk.

CONTEXT: Transitional disks are structures of dust and gas around young stars with large inner cavities in which planet formation may occur. Lopsided dust distributions are observed in the dust continuum emission at millimeter wavelengths. These asymmetrical structures can be explained as being the result of an enhanced gas density vortex where the dust is trapped, potentially promoting the rapid growth to the planetesimal scale. AIMS: AB Aur hosts a transitional disk with a clear horseshoe morphology which strongly suggests the presence of a dust trap. Our goal is to investigate its formation and the possible effects on the gas chemistry. METHODS: We used the NOEMA (NOrthern Extended Millimeter Array) interferometer to image the 1mm continuum dust emission and the 13CO J=2 →1, C18OJ=2 →1, SO J=56 →45, and H2CO J=303 →202 rotational lines. RESULTS: Line integrated intensity ratio images are built to investigate the chemical changes within the disk. The I(H2CO J=303 →202)/I(C18O J=2→1) ratio is fairly constant along the disk with values of ~0.15±0.05. On the contrary, the I(SO J=56 →45)/I(C18O J=2 →1) and I(SO J=56 →45)/I(H2CO J=303 →202) ratios present a clear northeast-southwest gradient (a factor of 3-6) with the minimum towards the dust trap. This gradient cannot be explained by a local change in the excitation conditions but by a decrease in the SO abundance. Gas densities up to ~109 cm-3 are expected in the disk midplane and two-three times larger in the high pressure vortex. We have used a single point (n,T) chemical model to investigate the lifetime of gaseous CO, H2CO, and SO in the dust trap. Our model shows that for densities >107 cm-3, the SO molecules are depleted (directly frozen, or converted into SO2 and then frozen out) in less than 0.1 Myr. The lower SO abundance towards the dust trap could indicate that a larger fraction of the gas is in a high density environment. CONCLUSIONS: Gas dynamics, grain growth and gas chemistry are coupled in the planet formation process. We detect a chemical signature of the presence of a dust trap in a transitional disk. Because of the strong dependence of SO abundance on the gas density, the sulfur chemistry can be used as a chemical diagnostic to detect the birthsites of future planets. However, the large uncertainties inherent to chemical models and the limited knowledge of the disk's physical structure and initial conditions are important drawbacks.