Massive shelf dense water flow influences plankton community structure and particle transport over long distance.

Dense waters (DW) formation in shelf areas and their cascading off the shelf break play a major role in ventilating deep waters, thus potentially affecting ecosystem functioning and biogeochemical cycles. However, whether DW flow across shelves may affect the composition and structure of plankton communities down to the seafloor and the particles transport over long distances has not been fully investigated. Following the 2012 north Adriatic Sea cold outbreak, DW masses were intercepted at ca. 460 km south the area of origin and compared to resident ones in term of plankton biomass partitioning (pico to micro size) and phytoplankton species composition. Results indicated a relatively higher contribution of heterotrophs in DW than in deep resident water masses, probably as result of DW-mediated advection of fresh organic matter available to consumers. DWs showed unusual high abundances of Skeletonema sp., a diatom that bloomed in the north Adriatic during DW formation. The Lagrangian numerical model set up on this diatom confirmed that DW flow could be an important mechanism for plankton/particles export to deep waters. We conclude that the predicted climate-induced variability in DW formation events could have the potential to affect the ecosystem functioning of the deeper part of the Mediterranean basin, even at significant distance from generation sites.

Phytoplankton cell lysis associated with polyunsaturated aldehyde release in the Northern Adriatic Sea.

Diatoms are able to react to biotic and abiotic stress, such as competition, predation and unfavorable growth conditions, by producing bioactive compounds including polyunsaturated aldehydes (PUAs). PUAs have been shown to act against grazers and either enhance or inhibit the growth of different phytoplankton and bacteria both in culture and in the field. Presence of nanomolar concentrations of dissolved PUAs in seawater has been reported in the North Adriatic Sea (Mediterranean), suggesting that these compounds are released in seawater following diatom cell lysis. However, the origin of the PUAs and their effects on natural phytoplankton assemblages remain unclear. Here we present data from four oceanographic cruises that took place during diatom blooms in the northern Adriatic Sea where concentrations of particulate and dissolved PUAs were monitored along with phytoplankton cell lysis. Cell lysis was positively correlated with both concentrations of particulate and dissolved PUAs (R = 0.69 and R = 0.77, respectively), supporting the hypothesis that these compounds are released by cell lysis. However, the highest concentration of dissolved PUAs (2.53 nM) was measured when cell lysis was high (0.24 d(-1)) but no known PUA-producing diatoms were detected, suggesting either that other organisms can produce PUAs or that PUA-producing enzymes retain activity extracellularly after diatom cells have lysed. Although in situ concentrations of dissolved PUAs were one to three orders of magnitude lower than those typically used in laboratory culture experiments, we argue that concentrations produced in the field could induce similar effects to those observed in culture and therefore may help shape plankton community composition and function in the oceans.

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.

Can selective soft tissue release and cuboid osteotomy correct neglected clubfoot?

BACKGROUND: Neglected clubfoot in older children is characterized by a stiff, nonreducible deformity with relative elongation of the lateral column of the foot with respect to the medial column. Surgical correction often has involved a double osteotomy with elongation of the medial column and shortening of the lateral column, or the use of an external fixator to achieve more gradual correction. Both approaches have shortcomings. QUESTIONS/PURPOSES: We therefore (1) used objective physical examination measurements and a functional assessment to evaluate the effectiveness of cuboid osteotomy combined with a selective soft tissue release to achieve correction of neglected clubfoot in older children, (2) determined the rate of complications, and (3) ascertained whether the initial correction achieved was maintained. METHODS: We reviewed 31 patients (56 feet) older than 5 years with severe, neglected nonreducible clubfoot deformity who underwent the index procedure. Minimum followup was 2 years (average, 6 years; range, 2-9 years). Postoperatively, the Laaveg and Ponseti classification and Dimeglio score were used to grade correction. Complication rates were tallied. RESULTS: According to the Laaveg and Ponseti classification, 24 feet showed excellent correction, 20 good, nine fair, and three poor at 1-year followup. These results were maintained up to the latest followup. Patients showed significant improvement of Dimeglio score after surgery (p < 0.0001). Two patients had postoperative skin-related complications that healed without additional surgery. CONCLUSIONS: Cuboid subtraction osteotomy combined with posteromedial release is an effective approach to manage a stiff nonreducible neglected clubfoot deformity in older children.

Congenital hip dysplasia treated by total hip arthroplasty using cementless tapered stem in patients younger than 50 years old: results after 12-years follow-up.

BACKGROUND: Congenital hip dysplasia may lead to severe acetabular and femoral abnormalities that can make total hip arthroplasty a challenging procedure. We assessed a series of patients affected by developmental hip dysplasia treated with total hip arthroplasty using cementless tapered stem and here we report the outcomes at long-term follow-up. MATERIALS AND METHODS: Twenty-eight patients (24 women and 4 men) aged between 44 and 50 years (mean 47 years) were observed. Clinical evaluation was rated with the Harris Hip Score. Radiographic evaluation consisted in standard anteroposterior and axial view radiographs of the hip. According to Crowe's classification, 16 hips presented dysplasia grade 1, 14 grade 2, and 4 grade 3. All patients were treated with total hip arthroplasty using a cementless tapered stem (Wagner Cone Prosthesis). Six patients were operated bilaterally, with a totally of 34 hips operated. After surgery, the patients were clinically and radiographically checked at 3, 6, and 12 months and yearly thereafter until an average follow-up of 12 years (range 10-14 years). RESULTS: Average Harris Hip Score was 56 ± 9 (range 45-69) preoperatively, 90 ± 9 (range 81-100) 12 months after surgery, and 91 ± 8 (range 83-100) at last follow-up. Radiographic evaluation demonstrated excellent osteointegration of the implants. Signs of bone resorption were present in 6 hips, nevertheless no evidence of loosening was observed and none of the implants has been revised. CONCLUSIONS: Even in dysplasic femur, the tapered stem allowed adequate stability and orientation of the implant. We consider tapered stem a suitable option for total hip arthroplasty in developmental hip dysplasia, also in case of young patients, thanks to the favourable long-term results.

Total hip arthroplasty in developmental hip dysplasia using cementless tapered stem. Results after a minimum 10-year follow-up.

Acetabular and femoral abnormalities make total hip arthroplasty in developmental hip dysplasia a challenging procedure. We present details of long-term follow-up of a series of patients affected by developmental hip dysplasia treated with total hip arthroplasty using a cementless tapered stem. Thirty-five hips in 20 patients (18 women and 2 men) aged between 44 and 60 years (mean 51 years) were observed. Clinical evaluation was conducted using the Harris Hip Score (HHS). Radiographic evaluation consisted in standard anteroposterior and axial view radiographs of the hip. According to Crowe's classification, 25 hips had grade 2 and 10 hips grade 3 dysplasia. All patients were treated with total hip arthroplasty using a cementless tapered stem (Wagner Cone Prosthesis™). After surgery the patients were clinically and radiographically evaluated at 1, 2, 3, 6 and 12 months and annually thereafter. The average follow-up was 12 years (range 10-14 years). The average HHS was 57±7 (range 45-66) preoperatively, 90±7 (range 81-100) 12 months after surgery and 90±6 (range 83-100) at last follow-up. Radiographic evaluation demonstrated excellent osseointegration of the implants in most cases. Signs of bone resorption were present in 5 hips, but no evidence of loosening was observed and none of the implants have been revised. The tapered stem achieved adequate stability and orientation, and may be a suitable option for total hip arthroplasty for arthritis following developmental hip dysplasia.

Surgical treatment of post-traumatic malalignment of the ankle.

Post-traumatic malalignment is evident in cases of malunion of ankle fractures. This condition predisposes to the development of chronic pain, functional impairment, and finally post-traumatic arthritis. The aim of this paper is to present a joint-saving surgical treatment of post-traumatic ankle malalignment. It is based on the review of a series of patients who developed fracture malunion and were treated with articular reconstruction. Twenty-two ankle fractures, which malunited and resulted into valgus deformity and fibular shortening are presented. Pre-reconstruction and mid-term follow-up evaluation included the AOFAS score and standard weight-bearing radiographs. Surgical treatment consisted in articular reconstruction with malleolar osteotomies. Post-operatively, the non-weight-bearing period extended to 6 weeks post-surgery, while full weight-bearing was allowed at 12 weeks on average. All osteotomies healed, while no intra-operative or early post-operative complications were reported. The average pre-operative AOFAS score was 45, while post-operatively climbed to 87. At the last follow-up, on average at 5-years post-surgery, 10 patients reported "excellent" function, 7 "good", 3 "fair" and 2 "poor" function. The correction of the malalignment was maintained in 20 cases. The two patients with poor function and loss of reduction underwent ankle fusion. Articular reconstruction with malleolar osteotomies is indicated for the treatment of ankle post-traumatic malalignment, offering reduction of pain, improvement of the ankle function, delaying the development of post-traumatic arthritis, and minimising the need of radical surgery such as ankle fusion or prosthetic replacement. Moreover, once a correct alignment of the joint is achieved, secondary surgery, if necessary, can be performed more easily, and with better results.

Nonoperative treatment of closed displaced midshaft clavicle fractures.

BACKGROUND: closed displaced midshaft clavicle fractures used to be treated nonoperatively, and many studies have reported that nonoperative treatment gave good results. However, more recent studies have reported poorer results following nonoperative treatment, whereas the results of operative treatment have improved considerably. The aim of this paper was to report the results of treating closed displaced midshaft clavicle fractures nonoperatively. MATERIALS AND METHODS: one hundred Edinburgh type 2B clavicle fractures (69 type 2B1 and 31 type 2B2) in 100 patients (78 males and 22 females) aged between 18 and 67 ears (mean 32 years) were treated. All patients were treated using a figure-of-eight bandage. Clinical and radiographic assessment was performed at the time of trauma, 1, 2 and 3 months after the trauma, and then at an average follow-up of 3 years (range 1-5 years). The outcome was rated at the last follow-up using the DASH score. RESULTS: ninety-seven of the 100 fractures healed. Three nonunions were observed. Average healing time was 9 weeks (range 8-12 weeks). No statistically significant correlation between the type of fracture and the healing time was observed. The average DASH score was 24 (range 0-78) and, based on this score, 81 patients presented excellent results, 12 good, 5 fair, and 2 poor. No statistically significant correlation between the type of the fracture and the score was observed. CONCLUSIONS: we believe that nonoperative treatment is still appropriate in most cases, as it yields good results without incurring the potential complications of surgery.

Phytoplankton-bacterioplankton interactions and carbon fluxes through microbial communities in a microtidal lagoon.

The strength of the bacteria-phytoplankton coupling and the importance of the microbially mediated carbon fluxes have been investigated in a microtidal lagoon (Lagoon of Venice), with emphasis on the trophic variations, in a within-system perspective. The large trophic heterogeneity of the three stations considered corresponded to an elevated variability of phytoplankton biomass and production (from 0.1 up to 300 microg C L(-1) h(-1)), while bacteria standing stock and production (from 2 to 8 microg C L(-1) h(-1)) appeared, in comparison, to be much more constant. The relationships between bacteria and the phytoplankton community could not be related to the trophic state in a straightforward way; rather, some patterns common to the three stations could be evidenced. In particular, the two communities appeared to be clearly uncoupled, bacterial carbon demand (BCD) always exceeding dissolved primary production (DPP) and, mostly, also total primary production, independent of the station and the season considered. The occurrence of situations in which bacterial production was larger than primary production and the continuous prevalence of BCD over DPP implied that, quite independent of the trophic variability, sources of organic carbon other than phytoplankton production were necessary and available to sustain the bacterial metabolism in the Lagoon of Venice.