Microplastic accumulation and ecological impacts on benthic invertebrates: Insights from a microcosm experiment

Microplastic (MP) pollution poses a global concern, especially for benthic invertebrates. This one-month study investigated the accumulation of small MP polymers (polypropylene and polyester resin, 3-500 μm, 250 μg L-1) in benthic invertebrates and on one alga species. Results revealed species-specific preferences for MP size and type, driven by ingestion, adhesion, or avoidance behaviours. Polyester resin accumulated in Mytilus galloprovincialis, Chamelea gallina, Hexaplex trunculus, and Paranemonia cinerea, while polypropylene accumulated on Ulva rigida. Over time, MP accumulation decreased in count but not size, averaging 6.2 ± 5.0 particles per individual after a month. MP were mainly found inside of the organisms, especially in the gut, gills, and gonads and externally adherent MP ranged from 11 to 35 % of the total. Biochemical energy assessments after two weeks of MP exposure indicated energy gains for water column species but energy loss for sediment-associated species, highlighting the susceptibility of infaunal benthic communities to MP contamination.

Molecular and Morphometric Update on Italian Salicornia (Chenopodiaceae), with a Focus on the Species S. procumbens s. l

Salicornia is a highly taxonomically problematic genus due to the reduced morphological observable characters. Ten Eurasian species are currently recognized: S. alpini, S. europaea, S. fruticosa, S. hispanica, S. lagascae, S. perennans, S. perennis, S. persica, S. procumbens, and S. pruinosa. In addition, eleven subspecies are accepted, mainly based on their distribution areas. Along the Venetian coasts and in Sardinia, in the past, an endemic species called S. veneta was recognized, but this name was later synonymized with S. procumbens subsp. procumbens. The aim of the present research is investigating different Italian Salicornia populations by a molecular point of view, using the nuclear ribosomal external transcribed spacer ETS and the plastid psbA-trnH intergenic spacer. A particular focus is on the comparison between Venetian (including those occurring in locus classicus of S. veneta) and Sardinian S. procumbens and other Italian populations of this species. The molecular analyses based on the plastid marker highlight that the Italian S. procumbens populations form two well distinct groups. In particular, some of the Venetian (Locus classicus of S. veneta) and all the Sardinian specimens are genetically distinct (=plastid haplotype 1) from the other investigated populations (=plastid haplotype 2). This indicates that the psbA-trnH haplotype 1 glassworts represent a distinct entity, which we suppose to coincide with the former S. veneta. Therefore, we suggest to recognize this taxonomic entity at the subspecies rank, as S. procumbens subsp. veneta comb. and stat. nov. However, contrary to the results found with the plastid psbA-trnH intergenic spacer, the ETS locus does not show a separation into two distinct clades for S. procumbens, probably due to a different evolution of the two loci. Nevertheless, in the ETS phylogenetic reconstruction, the Sardinian specimens (=ribotypes 2 and 3) are placed, together with a Moroccan sample, in a subclade separated from all the other S. procumbens. These results suggest that the Sardinian populations can represent a subspecies/incipient speciation process, probably due to geographic isolation. In the light of this, morphometric analyses (k-means, MANOVA, PCA, DA, and Box-Plot) have been carried out on the Sardinian and Venetian populations to verify if this distinction is detectable also by a morphological point of view. The morphometric analyses highlight the existence of two groups, concerning both the nuclear and plastid trees. Six characters were found to be diagnostic.

Conservation actions for restoring the coastal lagoon habitats: Strategy and multidisciplinary approach of LIFE Lagoon Refresh

The Habitat Directive of European Union lists Costal Lagoons (habitat code 1150*) among priority habitats because they are in danger of disappearance. Natural ecosystems may recover from anthropogenic perturbations; however, the recovery can follow natural restoration or it can be redirected through ecological restoration by anthropogenic intervention. Accordingly, by collecting the available theoretical indications for restoration of estuarine and coastal areas, a methodological approach was detailed andit can be summarised into five issues: (i) Environmental context from which it began; (ii) Desired state to be achieved; (iii) Policies and socio-economic context; (iv) Typology of recovery and/or improvement of habitats and ecosystems; and (v) Methods for monitoring the impact of the project. The project strategy, management and measures of LIFE Lagoon Refresh were also presented and discussed, as a case study for the implementation of the multidisciplinary approach for restoration ecology in transitional waters. The project takes place in the northern Venice Lagoon (Italy), started in 2017 and it lasts 5 years. In the Venice Lagoon, since the 20th century, strong reductions of the typical salinity gradient of buffer areas between lagoon and mainland, and of reedbed extensions have occurred due to historic human interventions, with negative consequences on coastal lagoon habitats. To improve the conservation status of habitats and biodiversity of the area, the LIFE Lagoon Refresh project included several conservative actions, which are (i) the diversion of a freshwater flow from the Sile River into the lagoon; (ii) the restoration of intertidal morphology, through biodegradable structures; (iii) the reed and aquatic angiosperm transplantations with the involvement of local fishermen and hunters, and (iv) the reduction of hunting and fishing pressures in the intervention area. To achieve the restoration of the lagoon environment, the strategy of the project covered a combination of different aspects and tools, such as planning activities, through the involvement of local Institutions and communities; stakeholder’s involvement to increase awareness of environment conservation and socioeconomic value improvement; an ecological engineering approach; numerical models as supporting tool for planning and managing of conservation actions; environmental monitoring performed before and after the conservation actions.

Habitat heterogeneity: A confounding factor for the effect of pollutants on macrobenthic community in coastal waters

Discrepancies were found between Ecological Status of sediments evaluated though the analysis of macrobenthic community and chemical analyses along a heavily trafficked and contaminated maritime seaway in Tyrrhenian Sea. Chemical analyses showed some sites highly contaminated by PAHs and metals with values exceeding thresholds for Good Chemical status and representing potential toxicological risk for benthic animals. Conversely, macrobenthic communities were highly rich and diverse, with Ecological Status (through M-AMBI) Good and High at each site. Sampling depth, total organic carbon, and total nitrogen were the major factors influencing biotic indices (AMBI, M-AMBI, S, H), even if concentrations of PAHs and metals (V, As, and Fe) contributed in explaining a part of indices variability. Habitat heterogeneity of sampled sites is likely acting as a confounding factor for two reasons: (1) high variability of environmental parameters leads to high richness and diversity, to which M-AMBI is sensitive, and (2) environmental parameters explained part of the variability of indices, together with contaminants. Our results suggested the importance of considering natural variability as a fundamental step of environmental impact assessment, for the correct interpretation of biotic indices.

Environmental restoration by aquatic angiosperm transplants in transitional water systems: The Venice Lagoon as a case study

The paper reports the results obtained after 4 years of aquatic angiosperm transplants in areas of the Venice Lagoon (North Adriatic Sea, Mediterranean) where meadows almost disappeared due to eutrophication, pollution and overexploitation of clam resources. The project LIFE12 NAT/IT/000331-SeResto, funded by the European Union, allowed to recolonize the Habitat 1150* (coastal lagoons) in the northernmost part of the lagoon, by extensive manual transplants of small sods or single rhizomes of Zostera marina, Zostera noltei, Ruppia cirrhosa and, in some stations also of Cymodocea nodosa. Over the 4 years of the project more than 75,000 rhizomes were transplanted in 35 stations with the support of local stakeholders (fishermen, hunters and sport clubs). Plants took root in 32 stations forming extensive meadows on a surface of approx. 10 km² even if some failures were recorded in areas affected by outflows of freshwater rich in nutrients and suspended particulate matter. The rapid recovery of the ecological status of the involved areas was the result of this meadow restoration, which was in compliance with Water Framework Directive (WFD 2000/60/EC) objectives. Moreover, the monitoring of environmental parameters in the water column and in surface sediments allowed to identify the best conditions for successful transplants. Small, widespread interventions and the participation of local stakeholders in the environmental recovery, make this action economically cheap and easily transposable in other similar environments.

Temporal variation of floatable plastic particles in the largest Italian river, the Po

We investigated the temporal concentration of floatable plastic particles in the Po river, the largest contributor of freshwater to the Adriatic Sea. Surface waters were sampled in 2019 with a Manta trawl, with almost bimonthly frequency. In total, 5063 plastic particles were collected, 80.6% of which were microplastics (<5 mm). Characterization through FT-IR spectroscopy evidenced 7 polymers, of which polyethylene, polypropylene and polystyrene accounted for 40.5%, 25.7%, and 14.9%, respectively. The highest plastic concentration was recorded in December (3.47 particles m^-3; 5.89 mg m^-3), while the lowest in August (0.29 ± 0.01 particles m^-3; 0.22 ± 0.08 mg m^-3). We estimated the annual load of floatable plastic particles carried by the Po river to be 145 tons. Plastic particle load was correlated with the hydraulic regime, and was higher in autumn and spring months.

Microplastic accumulation in benthic invertebrates in Terra Nova Bay (Ross Sea, Antarctica)

Microplastic contamination of the benthic invertebrate fauna in Terra Nova Bay (Ross Sea, Antarctica) was determined. Twelve macrobenthic species, characterized by different feeding strategies, were selected at 3 sampling sites at increasing distance from the Italian Scientific Base (Mario Zucchelli, Camp Icarus, Adelie Cove). The 83% of the analyzed macrobenthic species contained microplastics (0.01-3.29 items mg^-1). The size of the particles, measured by Feret diameter, ranged from 33 to 1000 µm with the highest relative abundance between 50 and 100 µm. Filter-feeders and grazers displayed values of microplastic contamination from 3 to 5 times higher than omnivores and predators, leading to the hypothesis that there is no evident bioaccumulation through the food web. The prevalent polymers identified by micro-FTIR were nylon (86%) and polyethylene (5%); other polymers identified in Antarctic benthos were polytetrafluoroethylene, polyoxymethylene, phenolic resin, polypropylene, polystyrene resin and XT polymer.

Hazardous effects of silver nanoparticles for primary producers in transitional water systems: The case of the seaweed Ulva rigida C. Agardh

The acute toxicity of citrate capped silver nanoparticles (AgNP) and silver nitrate was evaluated on the marine macroalga Ulva rigida C. Agardh (1823). Silver bioaccumulation, ultrastructural chloroplast damages verified by TEM microscopy, inhibition of primary production, neutral lipid production and oxidative stress were observed after 24 h of exposure to AgNP. The toxic effects of silver nitrate in artificial seawater started from a concentration of 0.05 ppm and was more toxic than AgNP that produced effects from a concentration of 0.1 ppm. However only AgNP induced lipid peroxidation in U. rigida. The addition of natural organic and inorganic ligands, represented by transparent exopolymer particles (TEP) and clay, drastically reduced AgNP acute toxicity in a ratio AgNP:ligand of 1:100 and 1:200, respectively. The findings suggest a marked toxicity of Ag on marine macroalgae which however should be mitigated by the high natural ligand concentrations of the transitional environments.

The difficulty of disentangling natural from anthropogenic forcing factors makes the evaluation of ecological quality problematic: A case study from Adriatic lagoons

The complex and dynamic nature of transitional ecosystems pose problems for the assessment of the Ecological Quality Status required by the European Water Framework Directive (WFD; 2000/60/EC). In six Adriatic lagoons, Ecological Quality Status was studied by comparing a biotic index based on macrophytes (MaQI), and three indices based on invertebrates (M-AMBI, M-bAMBI, and ISD). Ecological Status evaluated though MaQI and ISD resulted in quite degraded ecosystems (moderate/poor/bad), with only opportunistic algae and macrobenthic communities dominated by small size classes. Those results were supported by physico-chemical parameters, indicating high nutrients inputs, and anthropogenic pressures related with agriculture and fishery activities. Ecological Status obtained with M-AMBI and M-bAMBI was higher, with some sites reaching even the "good" status. The best response to anthropogenic pressures, in terms of a pressure index, was obtained by M-AMBI and M-bAMBI. Nevertheless, the response of used metrics (such as AMBI and bAMBI) to environmental variables not related to anthropogenic impact, and the high heterogeneity of physical-chemical conditions within lagoons, represent potential problems for the correct evaluation of Ecological Status of transitional waters. When different metrics give different responses it becomes a problem for managers who cannot easily make a decision on the remedial measures. The disagreement among indices arose because of the different response of biological elements to different stressors, and because the different indices based on macroinvertebrates focused on different aspects of the community, providing complementary information. So urge the need to find alternative approaches for a correct assessment of Ecological Status, with the combination of different biological elements, and considering the development of new indices (e.g. M-bAMBI) or refinement of the existing ones.

Benthic studies in LTER sites: the use of taxonomy surrogates in the detection of long-term changes in lagoonal benthic assemblages

In benthic studies, the identification of organisms at the species level is known to be the best source for ecological and biological information even if time-consuming and expensive. However, taxonomic sufficiency (TS) has been proposed as a short-cut method for quantifying changes in biological assemblages in environmental monitoring. In this paper, we set out to determine whether and how the taxonomic complexity of a benthic assemblage influences the results of TS at two different long-term ecological research (LTER) sites in the Po delta region (north-eastern Italy). Specifically, we investigated whether TS can be used to detect natural and human-driven patterns of variation in benthic assemblages from lagoonal soft bottoms. The first benthic dataset was collected from 1996 to 2015 in a “choked” lagoon, the Valli di Comacchio, a lagoon characterised by long water residence times and heavy eutrophication, while the second was collected from 2004 to 2010 in a “leaky” lagoon, the Sacca di Goro, a coastal area with human pressure limited to aquaculture. Univariate and multivariate statistical analyses were used to assess differences in the taxonomic structure of benthic assemblages and to test TS on the two different datasets. TS seemed to work from species to family level at both sites, despite a higher natural variability of environmental conditions combined with multiple anthropogenic stressors. Therefore, TS at the family level may represent effective taxonomic surrogates across a range of environmental contexts in lagoon environments. Since the structure of the community and the magnitude of changes could influence the efficiency of taxonomic surrogates and data transformations in long-term monitoring, we also suggest periodic analyses at finer taxonomic levels in order to check the efficiency of the application of taxonomic substitutes in routine monitoring programmes in lagoon systems.

Long-term changes of the trophic status in transitional ecosystems of the northern Adriatic Sea, key parameters and future expectations: The lagoon of Venice as a study case

The determination of the trophic status of transitional ecosystems from the physico-chemical and biological point of view is one of the requirements of the European Water Framework Directive (WFD 2000/60/EC). In Italy, its determination is implemented by the Regional Agencies for Environmental Protection (ARPAs) that have activated multi-annual monitoring programs. However, as the availability of funds is increasingly scarce, the number of environmental parameters to detect environmental changes should be conveniently managed.

The high number of environmental parameters, nutrient and macrophyte datasets available for the LTER-Italia site “Venice lagoon” can be an useful tool to analyze the trophic changes over recent years and to foresee environmental evolutions. Nutrient data on a spatial basis have been available since 1948, whereas macroalgal maps date back to 1980. The aim of this paper is to highlight the changes of the trophic status of the lagoon since the middle of the 20th century by considering the concentrations of nutrients in the surface sediments and in the water column, the variation of some physico-chemical parameters and the biomass of macroalgae and also to foresee the way it will possibly evolve. In fact, after many anthropogenic impacts that in the second half of the 20th century affected the lagoon, starting from the year 2010, the ecological status is progressively improving. Nutrients show a significant reduction both in the water column and in surface sediments, and the macrophytes are represented by species of higher ecological value while the opportunistic species such as the Ulvaceae are in strong regression.

Spatial distribution, bioaccumulation profiles and risk for consumption of edible bivalves: a comparison among razor clam, Manila clam and cockles in the Venice Lagoon

Despite their ecological and economical relevance, a lack of data is still occurring about the distribution, abundance, bioaccumulation and risks for consumption of some edible bivalves. The present study has been carried out in the Venice Lagoon taking into account three bivalve species to investigate i) the possible relationship among the biological features-distribution, abundance and bioaccumulation patterns- of razor clams (Solen marginatus Pulteney, 1799), Manila clams (Ruditapes philippinarum Adams and Reeve, 1850) and lagoon cockles (Cerastoderma glaucum Poiret, 1789) and the hydrological features, namely sediment physico-chemical characteristics and contamination; ii) their specific role as bioindicators of inorganic contamination; iii) the possible risks for human health associated with the consumption of these edible bivalves. Results showed that species distribution and abundance, especially for razor clams, was mainly influenced by environmental conditions and sediment granulometric composition, above metal(loid) contamination. The contamination patterns were different among species, as Manila clam generally showed higher bioaccumulation values for most of the metal(loid)s, whilst lagoon cockles preferentially accumulated Ni. Eventually, a serious concern exists for the human consumption, for all species and investigated sites regarding As. This study will raise attention on the effects of bioaccumulation of inorganic pollutants by edible bivalves and risks for consumers' safety, especially concerning razor clams and cockles, for which a critical lack of data on metal(loid) bioaccumulation occurs from the Northern Adriatic Sea.

Macrophyte assemblage composition as a simple tool to assess global change in coastal areas. Freshwater impacts and climatic changes

Macrophyte assemblages are one of the most sensitive biological communities to assess anthropogenic impacts and climate changes. Community composition responds very quickly to environmental changes driving towards a predictable composition. The increase or decrease of the trophic status (i.e. nutrient concentrations, suspended particulate matter, Chlorophyll-a) and temperature are the most important factors responsible for the replacement of taxa of high ecological value (sensitive taxa) with opportunistic species. A qualitative and quantitative study of macrophytes in 4 areas along the coasts of the Northern Adriatic Sea, from Venice (Italy) to Savudrija (Croatia) and the analysis of river outflows in this region during one year (May 2012-April 2013) provided information about their spatial variability. The coasts of the Veneto Region and Friuli-Venezia Giulia, which are affected by significant freshwater inputs, showed a strong biodiversity reduction or a dominance of thionitrophilic taxa. No seagrasses colonized these areas. On the other hand, the coasts of Croatia had negligible fresh water inputs and macrophyte communities were dominated by sensitive taxa such as the seagrass Cymodocea nodosa and some species belonging to genus Cystoseira.

Preliminary Results On the Efficacy of Macroalgal Extracts Against Larvae of Aedes albopictus

Activity of ethanolic extracts of the algae Ulva rigida, Asparagopsis taxiformis, Dictyota dichotoma, and Cystoseira barbata, collected along Italian coasts, was tested against larvae of the Asian tiger mosquito ( Aedes albopictus), a vector of pathogens for animals and humans. Tests were carried out using 10 specimens of 3rd-stage larvae per test, following the World Health Organization standard protocol with minor modifications. Among algal extracts, only D. dichotoma was active against the larvae of Ae. albopictus. Ethanolic extracts of that species showed LC₉₀ (the concentration that kills 90% of larvae) and LC₅₀ (the concentration that kills 50% of larvae) values at 44.32 and 85.92 mg/liter, respectively. Based on the data obtained, D. dichotoma biometabolic extracts could be potential candidates as larvicide compounds to control Ae. albopictus, encouraging the use of macroalgae as natural resources in integrated vector management strategies.

Interannual heavy element and nutrient concentration trends in the top sediments of Venice Lagoon (Italy)

The elemental composition of surficial sediments of Venice Lagoon (Italy) in 1987, 1993, 1998 and 2003 were investigated. Zn and Cr concentrations resulted in higher than background levels, but only Cd and Hg were higher than legal quality standards (Italian Decree 2010/260 and Water Framework Directive 2000/60/EC). Contaminants with similar spatial distribution are sorted into three groups by means of correlation analysis: (i) As, Co, Cd, Cu, Fe, Pb, Zn; (ii) Ni, Cr; (iii) Hg. Interannual concentrations are compared by applying a factor analysis to the matrix of differences between subsequent samplings. A general decrease of heavy metal levels is observed from 1987 to 1993, whereas particularly high concentrations of Ni and Cr are recorded in 1998 as a consequence of intense clam fishing, subsequently mitigated by better prevention of illegal harvesting. Due to the major role played by anthropogenic sediment resuspension, bathymetric variations are also considered.

Linking food web functioning and habitat diversity for an ecosystem based management: a Mediterranean lagoon case-study

We propose a modelling approach relating the functioning of a transitional ecosystem with the spatial extension of its habitats. A test case is presented for the lagoon of Venice, discussing the results in the context of the application of current EU directives. The effects on food web functioning due to changes related to manageable and unmanageable drivers were investigated. The modelling procedure involved the use of steady-state food web models and network analysis, respectively applied to estimate the fluxes of energy associated with trophic interactions, and to compute indices of food web functioning. On the long term (hundred years) temporal scale, the model indicated that the expected loss of salt marshes will produce further changes at the system level, with a lagoon showing a decrease in the energy processing efficiency. On the short term scale, simulation results indicated that fishery management accompanied by seagrass restoration measures would produce a slight transition towards a more healthy system, with higher energy cycling, and maintaining a good balance between processing efficiency and resilience. Scenarios presented suggest that the effectiveness of short term management strategies can be better evaluated when contextualized in the long term trends of evolution of a system. We also remark the need for further studying the relationship between habitat diversity and indicators of food web functioning.

Description of a Multimetric Phytoplankton Index (MPI) for the assessment of transitional waters

A Multimetric Phytoplankton Index (MPI) is proposed to support management policies for the assessment of transitional ecosystems and the implementation of the European Water Framework Directive. The MPI incorporates Hulburt's dominance index, bloom frequency and Menhinick's diversity index, calculated on the basis of phytoplankton species composition. Chlorophyll a concentrations were also included, to provide biomass data and to guarantee continuity and comparison with past evaluations. The MPI was calculated by averaging the ratios of the resulting values of each metric to those of a reference site characterised by low anthropogenic impact. The MPI was set up using data from over a 10-year period in several stations in Venice Lagoon (North-western Adriatic region), a highly valuable and heterogeneous transitional environment, subject to significant anthropogenic pressures. The dataset included physico-chemical data, nutrient and contaminant concentrations. Statistical analyses allowed us to gauge the MPI's responses to anthropogenic pressures and to verify its reliability.

PCDD/F and dioxin-like PCB bioaccumulation by Manila clam from polluted areas of Venice lagoon (Italy)

POP bioaccumulation pathways in the clam Tapes philippinarum were examined for two years from juveniles to adult size. Two polluted sites, one with sandy sediment, the other muddy were compared with a reference site characterized by low contamination levels. Juvenile clams coming from a hatchery were reared both on the sediment and in nets suspended at 30 cm from the bottom. POP changes in clam tissue were related to the concentrations recorded in sediments and in the particulate matter during the entire fattening period. Results provided interesting data on the relationships between environmental contamination and bioaccumulation. Contrary to studies on the decontamination times of the clams collected in polluted areas, this work investigates the preferential clam bioaccumulation pathways during growth under different environmental conditions. In general POP bioaccumulation resulted to be correlated to concentrations in SPM rather than in sediments and was higher in S-clams rather than in B-clams.

The changing state of contamination in the Lagoon of Venice. Part 2: heavy metals

In order to verify whether pollution is increasing or decreasing, in 25 locations uniformly distributed in the central part of the Lagoon of Venice, a transitional environment suffering from man's urban and industrial activities, the same sampling scheme was repeated three times (in 1987, 1993 and 1998) over a 12-year period during which the lagoonal environment underwent substantial changes. Superficial sediments were sampled and analysed for heavy metals and total organic carbon contents, grain size and density. In general heavy metal contents were found to be correlated, with concentrations above the background level, e.g., for Hg, a concentration factor of 24 was observed in 1987. A temporal decrease in concentrations was observed for most of the metals. Detailed analysis on a smaller spatial scale showed that contamination significantly decreases from the inner border of the lagoon seawards, as highlighted in contour maps. The role of the Porto Marghera industrial zone as a source of pollutants at the border of the Lagoon was confirmed. The decrease in contamination could not be attributed only to a decrease in the intensity of sources, but also to erosion processes, worsened by intensive harvesting of clams with hydraulic dredges.

Sedimentation rates and erosion processes in the lagoon of Venice

Since the early 1990s in the lagoon of Venice, especially in the central basin, the surface sediment underwent high re-suspension and sedimentation changes and water turbidity increased both because of the disappearance of the macroalgal coverage and the harvesting of the Manila clam Tapes philippinarum Adams and Reeve, which had rapidly colonised the bottom free of macrophytes. Clams are harvested with hydraulic and mechanical dredges which remove and re-suspend surface sediments causing the transport and loss of the finest materials. Sediment transport and re-deposition in the lagoon have been monitored with sediment traps placed onto the bottoms near the Malamocco mouth (st. A), the Lido watershed (st. B) and the mainland (sts. C and D). From 1989-1993 to 1998-1999 sedimentation rates increased significantly at st. A (from 41 to 228 kg DW m(-2) year(-1)), st. B (from 65 to 760 kg DW m(-2) year(-1)) and st. C (from 140 to 721 kg DW m(-2) year(-1)), while at st. D sedimentation rates increased only by ca. 20%. In parallel sediment grain-size changed with a loss of the finest fraction especially near the mainland. The erosion or sedimentation status, acquired by utilizing sedimentation devices placed onto the bottoms, showed that sts. B, C, D were affected by sediment losses, while st. A, populated by seagrasses and characterised by seasonal variations which depend on the shoot development, did not show any significant bathymetric change on an annual basis. The highest sediment erosion was recorded at st. D (ca. 3.6 cm year(-1)) whereas a loss of ca. 1.5 and 0.5 cm year(-1) was found at sts. C and B, respectively, which accounted for a mean loss in the central lagoon of ca. 1.2 million tonnes year(-1). Those data agree with the previous indirect estimation of sediment loss which was based on the number of fishing boats operating in the lagoon on an annual basis.

Organic carbon changes in the surface sediments of the Venice lagoon

The concentrations of total, inorganic and organic carbon in the surface sediment of the central part of the Venice lagoon (31-55 stations) during the month of June in 1987, 1993 and 1998 were recorded. In two stations: San Giuliano and Lido, samples were collected on a monthly basis for 1 year also in different periods. On an average, by considering the whole central lagoon, inorganic carbon (IC) and total carbon (TC) did not show significant changes. In contrast organic carbon (OC) had alternating trends showing a decrease from 1987 to 1993, due to the almost complete disappearance of huge macroalgal biomasses, and a marked increase from 1993 to 1998, because of the high sediment disturbance caused by the catching of the clam Tapes philippinarum Adams & Reeve which had colonised the sediment free of macrophytes. The carbon changes monitored in the two stations studied on a seasonal basis during different years not only confirmed such results, but also enhanced the effects of fishing activities at Lido station and those depending on the disappearance of macroalgae at S. Giuliano. Moreover, this paper underlines the importance of seagrass beds. In fact in the areas colonised by those plants the percentage of fine sediments and organic matter is on the increase, while erosive processes are contrasted.

Recording the occurrence of trophic level changes in the lagoon of Venice over the '90s

Four areas of the Venice lagoon, placed near the Malamocco mouth (Alberoni, st. A), in the Lido watershed (Sacca Sessola, st. B) and near the mainland under the influence of freshwater and urban (San Giuliano, st. C) or industrial (Fusina, st. D) effluents were monitored in two periods: 1989-92 and 1998-99 in order to quantify some environmental changes (macroalgal and phytoplankton biomass, nutrient concentrations, physico-chemical variables) occurred in both the water column and the surface sediment over the '90s. Stations B and C, two areas particularly affected by macroalgae exhibited a biomass of ca. 20 and 8 kg WW m(-2), respectively, during 1989-90. In 1998-99 maximum densities decreased to ca. 0.3 and 0.01 kg WW m(-2). During that period, phytoplankton also decreased significantly both in peaks (Chl a: from 58-86 to 4.0-3.5 microg dm(-3)) and mean values (Chl a: from 9.1-10.3 to 1.3-1.4 microg dm(-3)), especially at sts. C and D. As far as nutrient concentrations are concerned, a different trend was observed in the water column and in the surface sediment, mainly because of the reduction of the primary producers and the disappearance of anoxic crises. In 1998-99 reactive phosphorus (RP) in the water column was up to ca. 3 times as high as in 1989-92. Conversely, dissolved inorganic nitrogen (DIN) was not significantly changed. In 1998-99 the 5 cm sediment top layer at sts. B, C, displayed a significant total nitrogen (TN) and total phosphorus (TP) decrease (TN annual mean: from 1.29 and 2.79 mg DW g(-1) to 0.69 and 1.47 mg DW g(-1), respectively; TP: from 401 and 626 microg DW g(-1) to 360 and 455 microg DW g(-1)). A different result was found at st. A which in 1998-99 was colonised by the seagrass Zostera marina L. That station showed a TN sediment increase from 0.25 to 0.67 mg DW g(-1) and a TP decrease from 455 to 350 microg DW g(-1). Station D, which did not show any macrophyte biomass coverage either in 1992-93 or in 1998-99, exhibited negligible differences. Besides the monitoring of biomasses and nutrients, significant changes related to oxygen concentration, water transparency, pH and E(h) and sediment rates were also recorded.

The changing state of contamination in the Lagoon of Venice. Part 1: organic pollutants

The Lagoon of Venice is a transitional environment suffering from industrial, urban and agricultural impact. Recently the mechanical clam fishing, preventing a regular deposition of sediments has made sampling of cores suitable for radiodating very problematic. Therefore, in this study, in order to assess temporal and spatial trends of contamination, the same sampling scheme was repeated three times over a 12-year period. The concentrations of PCBs, PAHs and organochlorine pesticides were measured in the uppermost 5 cm of sediments collected in 25 sites in the central portion of the lagoon during three campaigns conducted in 1987, 1993 and 1998. Analytical results, validated statistically, indicated that, while PCB and pesticide concentrations tend to decrease during the considered period of time, PAH do not, showing that the input rate of these compounds to the lagoon environment is still important. A spatial trend of pollution was also found in the lagoon for PCBs and pesticides, which decrease from the sources, namely the industrial zone and the mouths of rivers, to areas closer to the sea: a reduction up to 80% and 90%, respectively, was monitored. PAH contamination, originating chiefly from incomplete combustion of fossil fuels, as inferred from ratios of congeners, was mainly located around the historical center of Venice, where most of the boat traffic is concentrated and has an increasing trend.

Seasonal evolution of heavy metal concentrations in the surface sediments of two Mediterranean Zostera marina L. beds at Thau lagoon (France) and Venice lagoon (Italy)

The concentrations and the seasonal changes of heavy metals and organic carbon in the sediments underlying a Zostera marina L. bed were measured monthly during one year, in two Mediterranean lagoons: Thau (France) and Venice (Italy). While at Thau sediments showed Cu (18.7+/-3.9 microg g-1) and Pb (13.8+/-3.8 microg g-1) average concentrations twofold higher than at Venice (Cu: 8.4+/-4.8 microg g-1; Pb: 6.1+/-0.70 microg g-1), the Italian site exhibited average concentrations of Fe (13383+/-955 microg g-1 versus 6098+/-1089 microg g-1 at Thau), Mn (339+/-12 microg g-1 versus 190+/-23 microg g-1 at Thau), Zn (61.6+/-12.7 microgg -1 versus 36.1+/-7.4 microg g-1 at Thau), Cr (47.3+/-7.3 microg g-1 versus 21.8+/-8.0 microg g-1 at Thau) and Ni (12.7+/-1.7 microg g-1 versus 8.9+/-3.1 microg g-1 at Thau) approximately 1.5-2 times as high as the French site. The organic carbon concentration was systematically higher at Thau (1.0+/-0.3) than at Venice (0.7+/-0.2). A significant seasonal fluctuation was found for Zn, Cu, Ni, Cr in both lagoons while no significant variations were recorded for Pb at Venice and for Cd at Thau. Some of those changes appeared to be significantly correlated with the biomass of Zostera at Thau and the concentration of organic carbon at Venice.

Temporal and spatial changes of macroalgae and phytoplankton in a Mediterranean coastal area: the Venice lagoon as a case study

Since the late 1980s the lagoon of Venice, a shallow Mediterranean coastal area, has experienced strong environmental changes. Macroalgae, which were the predominant primary producers of the lagoon, reduced markedly, but neither phytoplankton nor seagrasses replaced them. Temporal and spatial changes in macroalgal standing crop (SC) and phytoplankton concentration were investigated between 1987 and 1998. Maps of macroalgal SC show a marked declining trend. Biomass in fresh weight decreased from: 558 ktonnes in 1987, to 85 ktonnes in 1993 and to 8.7 ktonnes in 1998. As a whole, the biomass in 1998 was only 1.6% of the biomass recorded in 1987. Similarly the macroalgal net (NPP) and gross (GPP) primary production decreased from ca. 1502 and 9721 ktonnes year(-1) to ca. 44 and 229 ktonnes year(-1), respectively. In the early 1990s the clam Tapes philippinarum Adams & Reeve and seagrasses, especially Zostera marina Linnaeus, colonised the bottoms free of macroalgae, but the development of intense clam-fishing activities prevented both phytoplankton blooms and seagrass spreading. Maps of chlorophyll a drawn according to data collected in parallel to macroalgal standing crop show unchanged concentrations. Macroalgae changes are enhanced by comparing annual trends in four areas of the central lagoon during 1989-1992 and 1998-1999. In those areas phytoplankton also decreased significantly. Marked changes of some environmental variables strongly associated with the primary production were recorded both during the lagoon mapping and in the areas studied on a yearly basis.

Estimation of PCDD/F distribution and fluxes in the Venice Lagoon, Italy: combining measurement and modelling approaches

The available experimental information on the occurrence of PCDD/Fs in the Venice Lagoon, Italy, was compiled and used to calculate fugacities for the environmental compartments of sediment, suspended particulate matter (SPM), water and air and then used to estimate fugacity ratios and assess the likely net direction of flux between media. The bottom sediment: SPM fugacity ratios for different PCDD/Fs indicate conditions close to equilibrium, suggestive of the close coupling of SPM with re-suspended sediment. Sediment/water and the sediment/air fugacity ratios suggest that net flux directions vary depending on the congener and the location within the lagoon. Net sediment-water-air movement (i.e. re-mobilisation/volatilisation) is suggested for the lighter congeners from the industrial canals, where the highest PCDD/F concentrations in the lagoon occur. The tendency to volatilise increases with decreasing congener molecular weight. In contrast, net deposition (air-water-sediment) appears to be occurring for the heaviest (hepta- and octa-) substituted PCDD/Fs. OCDF represents a marker of the industrial district of the lagoon, decreasing in concentration and as a fraction of total PCDD/Fs with increasing distance. The fugacity-based quantitative water air sediment interaction (QWASI) mass-balance model was applied to the central part of the lagoon. The key parameters for the determination of the model output, identified by a sensitivity analysis, were: the sediment active depth, the sediment re-suspension and deposition rates, and the total input of PCDD/Fs to the system. The QWASI model also indicates the tendency for the lighter PCDD/Fs to be released from surface sediment to the water column.

Heavy metal contamination in the seaweeds of the Venice lagoon

The concentrations of heavy metals (Fe, Zn, Cu, Cd, Ni, Pb, Cr, As) were determined in seven seaweeds of environmental and commercial relevance (Ulva rigida C. Ag., Gracilaria gracilis (Stackhouse) Steentoft, L. Irvine and Farnham, Porphyra leucosticta Thuret, Grateloupia doryphora (Montagne) Howe., Undaria pinnatifida (Harv.) Suringar, Fucus virsoides J. Agardh, Cystoseira barbata (Good. et Wood.) Ag.) collected in four sampling sites in the lagoon of Venice, in spring and autumn 1999. Metals were extracted using hot concentrated acids in a Microwave Digestion Rotor and analysed by absorption spectrophotometry using a flame mode for Fe and Zn and a graphite furnace for Pb, Cr, Cd, Cu, Ni and As. High contamination levels, especially for Pb, were detected in Ulva and to a lesser extent in Gracilaria. Brown seaweeds, especially Cystoseira was highly contaminated by As. The least contaminated genera with all metals except As were Porphyra and Undaria. A concentration decrease for Zn and Cd was observed from the inner parts of the central lagoon, close to the industrial district, towards the lagoon openings to the sea.

Growth rate of Ulva rigida in different Mediterranean eutrophicated sites

The growth of juvenile populations of Ulva rigida C. Agardh was measured by means of immersion in in situ cages against environmental parameters (temperature, incident light, salinity, dissolved inorganic nitrogen and dissolved reactive phosphorus) in four different eutrophicated southern sites: Channel of the Thau lagoon (France), Lido, Sacca Sessola and Fusina stations (Venice lagoon, Italy). The growth curves as a function of temperature showed that, in all cases, the maximal temperature for Ulva growth was 17 degrees C (limitation in growth below 7 degrees C and above around 25 degrees C). The growth analysis of these four sites showed seasonal differences. In the least eutrophicated and calmest Lido station, grazing and dissolved reactive phosphorus (seven times lower at Lido than at Thau) played a key role. At Thau and Fusina, which are eutrophicated and turbid environments, the incident light had a strong impact on growth. Sacca Sessola, with an intermediate position between the above two mentioned situations, showed the highest growth rate. The values and relative growth rate (RGR) curves of the Mediterranean and open-sea northern sites are discussed. In particular, the temperature defines the type of growth curve (unimodal or bimodal) and the incident light is responsible for the low Mediterranean RGR values (<10% day(-1)).

Evidence of a threshold value of glycated hemoglobin to improve the course of renal function in type 2 diabetes with typical diabetic glomerulopathy

We recently observed that the course of glomerular filtration rate (GFR) rapidly declines in a subgroup of Type 2 diabetic patients (D) with abnormalities of albumin excretion rate (AER) and typical diabetic nephropathy, despite tight blood pressure control. The aim of this study was to evaluate whether amelioration of blood glucose control, using insulin, improves the course of GFR. GFR decay was measured by spline modeling analysis of the plasma clearance rate of 51CR-EDTA, assessed every 6 months. We identified two groups of D using morphometric analysis of renal biopsy, who had values of glomerular basement membrane (GBM) and fractional mesangial volume (Vv mes/glom) respectively below (Group A: 38) or above (Group B: 50) the mean+2SD of values found in 27 kidney donors (GBM: 389 nm; Vv mes/glom: 0.25), as previously described in detail. Median AER was similar at base line in the 2 groups (109 microg/min, 29-1950, in Group A, 113 microg/min, 37-1845, in Group B; n.s.). Conventional metabolic therapy (sulphonylureas and/or biguanides) was used both in Group A and B during a 3 year follow-up period (Period 1). Group B was further divided in two subgroups with body mass index below (Group B, a) and above (Group B, b) the value of 30 kg/m2. Mean +/- SD HbA1c was 8.2 +/- 1.6% in Group A, 8.3 +/- 1.7% in Group B (a) (n.s.) and 9.1 +/- 1.7% in Group B (b) (n.s.). Tight blood pressure control was achieved and maintained using angiotensin converting enzyme inhibitors and/or beta blockers and/or calcium antagonists and/or thiazides. The mean arterial blood pressure (MAP) was 92 +/- 3 mmHg in Group A and 91 +/- 4 mmHg in Group B (n.s.). GFR decay was significantly greater in Group B than in Group A (Group A vs B: +1.21 +/- 0.71 vs -5.86 +/- 1.61 ml/min/1.73 m2/year). Median AER significantly rose in Group B (177 microg/min, p<0.05 vs base line) but not in Group A (134 microg/min, n.s.) during the third year of follow-up. Groups A and B were then followed over 4.1 years (range 3.1-4.4) (Period 2) maintaining the above described antihypertensive regimen, resulting in MAP values similar to those described during Period 1. Group A patients were treated with the same conventional glycemic control during Period 2. Group B (a) was conversely treated with intensive insulin therapy to achieve a HbA1c value below 7.5% (3 daily injections of regular and 1 or 2 daily injections of intermediate acting insulin associated with metformin 500 mg twice daily in 64% of the patients). Group B (b) patients were only treated by metformin (850 mg thrice daily) to achieve a HbA1c value below 7.5%. HbA1c decreased below the 7.5% target value in Group B (a) (7.0 +/- 1.6%, p<0.01 vs Period 1), but not in Group B (b) (8.0 +/- 1.6%, p<0.05 vs Period 1) and in Group A (8.3 +/- 1.7%, n.s. vs Period 1). The GFR decay of Group B, a during Period 2 was lower than that during Period 1 (Period 1 vs Period 2: -5.9 +/- 1.8 vs -1.8 +/- 0.7 ml/min/1.73 m2/year, p<0.01). GFR decay during Period 2 was similar to that observed during Period 1 in Group A (Period 1 vs Period 2: +1.21 +/- 0.71 vs +0.7 +/- 0.6 ml/min/1.73 ml/year, n.s.) and in Group B (b) (Period 1 vs Period 2: -4.4 +/- 0.71 vs -4.2 +/- 0.6 ml/min/1.73 m2/year, n.s.). Median AER did not significantly change in the fourth year of Period 2 , either in Group A or B (Group A vs B: 141 vs 152 microg/min, n.s.). In conclusion, our findings seem to suggest that amelioration of blood glucose control is attained both by insulin and metformin intensive treatment, but only insulin decreases and maintains HbA1c levels below 7.5%. These pattens of HbA1c appear to be a threshold value in order to significantly blunt GFR decay in a subgroup of Type 2 diabetic patients with typical diabetic glomerular lesions, who are less responsive to tight blood pressure control alone. Conversely, the cohort of patients with less severe diabetic glomerulopathy steadily show constant GFR patterns, despite similar abnormalities of albumin excretion rate, and HbA1c average values above 7.5%.

Benthic macrofauna changes in areas of Venice lagoon populated by seagrasses or seaweeds

Two areas of the Venice lagoon populated by seagrasses (three stations covered by Cymodocea nodosa (Ucria) Asherson, Zostera marina Linnaeus, Zostera noltii Hornemann) or seaweeds (two stations: one covered by Ulva rigida C. Agardh and another at present without seaweed biomass) were monitored by means of six surveys over a year in order to study macrofaunal composition and seasonal changes. The seagrass stations showed a mean species richness (28-30 S m(-2)), individual abundance (1854-4018 N m(-2)) and biomass (22.3-37.7 g m(-2) ash-free-dry-weight, AFDW) ca. 3-8 times higher than those populated by seaweeds (10-15 S m(-2), 494-1395 N m(-2) and 5.6-13.7 g m(-2) AFDW). Differences among seagrass or seaweed stations were much lower. The Ulva-dominated station showed a macrofauna completely different both from the other stations and the communities recorded ca. 30 years ago, before the prolific growth of Ulva. In this station, frequent biomass decompositions and anoxic crises created critical conditions for life favouring organisms with reduced life cycles, younger individuals and the epifaunal species instead of the infaunal ones. In particular, Ulva grazers and scrapers such as Gammarus aequicauda Stock and Gibbula adriatica Philippi were found to be by far the most abundant species, whereas the taxa characteristic of the associations found in the past, in the presence of seagrasses or seaweeds and typical of low eutrophicated environments, appear strongly reduced. Marked differences in the macrophyte dominance and in the bio-physico-chemical variables which characterise the main environmental conditions of the Venice lagoon support the different distribution and composition of macrofaunal communities. Seaweed stations appear mainly governed by the seasonal cycles of these un-rooted macrophytes which, by alternating periods of production and decomposition, are responsible for the drastic reduction of macrofauna biodiversity and biomass. Conversely, seagrass stations exhibit a better oxidisation of the environment and show conditions more favourable for macrofauna colonisation, especially in the presence of macrophytes which are characterised by very well developed below-ground systems such as Cymodocea nodosa.

Macrofauna impact on Ulva rigida C. Ag. production and relationship with environmental variables in the lagoon of Venice

The grazing pressure of the macrofaunal invertebrates associated with the biomass of Ulva rigida in the Venice lagoon, their species composition and relationship with environmental variables have been studied. Fifteen sampling campaigns were carried out during different seasons both in the central basin of the lagoon, dominated by macroalgae (especially U. rigida C. Ag.) and in the southern basin, prevalently populated by seagrasses (especially Zostera marina L.). Replicate experiments were conducted in the field by exposing Ulva fronds in net cages of 10 and 1 mm (control) mesh-sizes to allow or prevent grazer entrance. The grazing pressure was determined as Ulva growth rate difference in the cages. In the absence of invertebrate herbivores, Ulva exhibited per cent relative growth rates (%RGRs) ranging from 1.5 to 9.5% day(-1), whereas in their presence the %RGRs were significantly lower (from -2.5 to 3.4% day(-1)) and frequently negative, especially in the station dominated by macroalgae. In this area, peak grazing rates and macrofauna biomasses of up to 8.6% day(-1) and 1,480 g m(-2) fwt (84.4 ash-free dry weight), respectively, were found. On the whole, during in field experiments in the Ulva-dominated station, herbivores removed an amount of biomass whose percentage ranged from 59 to 165% (mean: 103%) of the biomass yield (grazers excluded) found in the cages. These results suggest the possibility that grazers could act as an important factor affecting Ulva production in the Venice lagoon. Macrofauna populations were analysed by means of multivaliate techniques applied to biological variables only and biological and environmental variables together. Data of individual abundance, after a log(x + 1) transformation and the calculation of the Bray-Curtis matrix, were classified using the Cluster Analysis and ordinated by means of the Non-Metric Multidimensional Scaling (MDS) technique, in accordance with the strategies used in the study of multispecies distributions. Finally, biological and environmental variables were analysed together by means of correlation matrices and the Principal Component Analysis.

Course of renal function in type 2 diabetic patients with abnormalities of albumin excretion rate

Heterogeneity in renal structure has been described in type 2 diabetic patients with both microalbuminuria and proteinuria; in fact, only a subset of type 2 diabetic patients have the typical diabetic glomerulopathy. However, it is currently unknown whether abnormalities in albumin excretion rate (AER) have a different renal prognostic value depending on the underlying renal structure. Aims of this study were: 1) to study the course of renal function in type 2 diabetic patients with altered AER; 2) to evaluate the relationship between the course of glomerular filtration rate (GFR) and renal structure; and 3) to evaluate the relationship between the course of GFR and baseline AER levels, metabolic control, and blood pressure levels during a follow-up period of 4 years. A total of 108 type 2 diabetic patients, 74 with microalbuminuria (MA) and 34 with proteinuria (P), were recruited into a prospective study that encompassed: 1) a baseline kidney biopsy with morphometric measurements of glomerular parameters; 2) intensified antihypertensive treatment for an average 4-year period (blood pressure target <140/90 mmHg); and 3) determinations of GFR at baseline and every 6 months. Mean (+/- SD) GFR significantly decreased from baseline in both MA (-1.3+/-9.4 [95% CI -3.51 to +0.86], P < 0.05) and P (-3.0+/-13.0 ml x min(-1) x 1.73 m(-2) per year [-7.71 to +1.61], P < 0.01). However, the changes in GFR were quite heterogeneous. Thus, on the basis of percent GFR change per year from baseline (delta%GFR), both MA and P patients were defined as progressors or nonprogressors when they were below or above the median, respectively. Baseline parameters of glomerular structure had a strong influence on the course of GFR. Indeed, the odds ratios of being progressors significantly increased across the quartiles of baseline glomerular basement membrane (GBM) width and mesangial fractional volume [Vv(mes/glom)], being 2.71 and 2.85 higher, respectively, in the fourth quartile than in the first quartile (P < 0.01 for both). Conversely, nonprogressors outnumbered progressors in the first quartile of GBM width (odds ratio: 2.14, P < 0.05) and in the first quartile of Vv(mes/glom) (odds ratio: 2.28, P < 0.01). Baseline albumin excretion rate (AER) did not influence delta%GFR; in fact, the number of progressors did not increase across quartiles of baseline AER among either MA or P. Similarly, mean blood pressure levels during follow-up (and intensified antihypertensive therapy) did not affect the course of GFR: the number of progressors and nonprogressors did not change across quartiles of mean blood pressure. In contrast, HbA1c during follow-up had an impact on delta%GFR: the odds ratio for being a progressor increased across quartiles of HbA1c, particularly for the highest quartile (HbA1c >9.0%). In conclusion, the course of renal function is heterogeneous in type 2 diabetic patients with microalbuminuria or proteinuria. In fact, a subset of patients has a rapid decline in GFR over a 4-year follow-up period; these patients have more advanced diabetic glomerulopathy and worse metabolic control than the remaining patients, whose GFR remains stable. These two cohorts are otherwise undistinguishable as regards the degree of AER at baseline and tight blood pressure control. Kidney biopsy has an important prognostic role in these patients. Thus, tight blood pressure control, when not associated with satisfactory glycemic control, is unable to prevent rapid GFR decline in type 2 diabetic patients with typical diabetic glomerulopathy.

Polymorphisms of angiotensin-converting enzyme and angiotensinogen genes in type 2 diabetic sibships in relation to albumin excretion rate

Familial clustering of altered albumin excretion and nephropathy risk has been described in both type 1 and type 2 diabetes; moreover, an association of micro-macroalbuminuria and diabetic retinopathy has been recently reported in a large number of white families with type 2 diabetes. Conflicting reports, mainly comparing affected with unaffected unrelated subjects, have suggested a possible role of some genotypes of the renin-angiotensin system in conferring nephropathy risk in type 2 diabetes. To examine the role of genetic factors in influencing albuminuria in families, we studied the relation of angiotensin-converting enzymes (ACE) and angiotensinogen (AGN) genotypes with albumin excretion rate in a population of affected siblings of type 2 diabetic probands. We determined ACE insertion/deletion polymorphism and two polymorphisms of the AGN gene (T174M and M235T) in 160 families with at least one affected member. Defining proband as the patient with the longest known duration of diabetes, we compared the allelic distribution in diabetic probands with and without altered albumin excretion and in their siblings. Allelic distribution of these polymorphisms was similar in the two groups of probands, as well as in their siblings. Identity-by-State (IBS) analysis showed a link between AGN locus and arterial hypertension in these siblings, which was independent from the degree of renal involvement. Thus, our findings suggest that in white families with type 2 diabetes, there is no linkage between the degree of albumin excretion and ACE and AGN polymorphisms, whereas the latter is related to arterial hypertension, as previously found in patients without diabetes but with essential hypertension.

Efficacy of antihypertensive therapy in decreasing renal and cardiovascular complications in diabetes mellitus

The mechanism underlying the pathogenesis of microangiopathy and macroangiopathy in diabetes mellitus is hypothesized to be chronic hyperglycaemia. However, the values of blood glucose at which chronic diabetic complications develop at the renal and cardiac level are quite different. It is not clear whether this is due to different responses of kidney and heart tissues to the metabolic challenge of diabetes, or to the simultaneous role of other mechanisms contributing differently to the pathogenesis of chronic diabetic complications in renal and cardiac tissues. One of these mechanisms could be the simultaneous occurrence of arterial hypertension along with hyperglycaemia in diabetic patients. We reviewed the available evidence in the recent medical literature and provide information on the relationships between hyperglycaemia and cardiovascular and renal complications in insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM). The majority of reports indicate that the values of blood glucose appearing to be at threshold level for the development of cardiovascular complications are significantly lower than those determining renal complications (5.4 vs 10.0 mmol/l blood glucose concentrations 2 h after an oral glucose tolerance test). This was the case both in cross-sectional and prospective studies and also in intervention studies aimed at decreasing blood glucose concentrations by using strict metabolic control methods (The Diabetes Control and Complications Trial Research Group), which succeeded in delaying the rate of occurrence of microangiopathic complications at the kidney and retinal level but not so effectively at the cardiac level. Therefore, alternative therapeutic or supplementary strategies to blood glucose control should be adopted in diabetes to prevent diabetic complications. To date, the most effective approach, from our point of view, is antihypertensive therapy in order to prevent end-stage renal disease. We extensively reviewed the available literature which reported comparisons between angiotensin-converting enzyme inhibitors (ACE inhibitors) and calcium channel blockers (CCBs) in the treatment of arterial hypertension in diabetes. Intensified antihypertensive therapy achieving a blood pressure level below 130/85 mmHg has been shown to be useful in decreasing the rate of occurrence of chronic diabetic complications in diabetes mellitus. Both ACE inhibitors and CCBs have been shown to significantly improve the course of renal function in diabetic patients with incipient and overt nephropathy.

Intracellular calcium handling by fibroblasts from non-insulin dependent diabetic patients with and without hypertension and microalbuminuria

Intracellular calcium ([(Ca2+)i]) plays a role in many cellular functions, and is involved in the pathogenesis of some conditions observed in non-insulin dependent diabetic patients (NIDDM), such as hypertension and insulin resistance. Hyperinsulinemia and hyperglycemia are also implicated in the pathogenesis of chronic diabetes complications. It is not clear whether disturbances in [(Ca2+)i] are accounted for only by metabolic abnormalities of diabetes or by other mechanisms. The aim of this study was to investigate [(Ca2+)i] handling by skin fibroblasts in NIDDM patients with similar features regarding diabetes duration and metabolic control, but who differ concerning blood pressure levels and albumin excretion rate. Using a fluorimetric technique with the indicator Fura-2/ AM, we investigated the effect of chronic exposure to insulin and glucose on [(Ca2+)i] after FGF stimulation in fibroblasts from NIDDM with hypertension alone (NIDDM H+M-) and with hypertension and microalbuminuria (NIDDM H+M+) in comparison with normotensive normoalbuminuric NIDDM (NIDDM H-M-) and control subjects (C). We studied also a group of hypertensive non-diabetic subjects (HYPER). We found that (1) FGF increases [(Ca2+)i] in all subjects; (2) insulin or high glucose per se increase [(Ca2+)i] in NIDDM H+M+ and NIDDM H+M- with respect to NIDDM H-M- and C; (3) HYPER show a [(Ca2+)i] response similar to that of NIDDM H+M- and NIDDM H+M+; (4) when stimuli are combined, all NIDDM have altered [(Ca2+)i] with respect to C, but NIDDM H+M-, NIDDM H+M+ and HYPER have higher values than NIDDM H-M-. This disorder in [(Ca2+)i] appears to be an intrinsic feature of a subgroup of hypertensive NIDDM patients, which persists in cultured cells, at least partially independent of the metabolic challenge of diabetes in vivo, and could contribute to the development of their renal and cardiovascular complications.