Limb Salvage by Means of Hindfoot Arthrodesis Utilizing Bulk Allograft and External Fixation.

FORMAT: Retrospective Review. LENGTH OF FOLLOW-UP: 18 months. CLASSIFICATION: Rearfoot and Ankle Reconstruction. METHODOLOGY: Level 4 Retrospective Review. PROCEDURES: A retrospective review was performed of 6 patients who had undergone limb salvage procedures between January 2016 and April 2019. Patients underwent surgery due to severe limb-threatening diagnosis including Charcot and/or osteomyelitis. Salvage arthrodesis was performed with bulk femoral head allograft incorporation using a hexapod external fixation system. The external fixation was retained for an average of 16 weeks. All patients were followed for a postoperative period of 16 months. RESULTS: Successful rearfoot arthrodesis and limb salvage was achieved in ⅚ (83%) of patients. DISCUSSION: This review demonstrates that limb salvage and arthrodesis are possible using femoral head allograft incorporation by external fixation alone. The involved patients had resolution of the osteomyelitis and Charcot deformity, salvage arthrodesis of the rearfoot and avoidance of a major limb amputation. LEVELS OF EVIDENCE: IV.

Influence of iron precipitated condition and light intensity on microalgae activated sludge based wastewater remediation.

The indigenous microalgae-activated sludge (MAAS) process during remediation of municipal wastewater was investigated by studying the influence of iron flocculation step and light intensity. In addition, availability of total phosphorous (P) and photosynthetic activity was examined in fed-batch and batch mode under northern climatic conditions and limited lighting. This was followed by a semi-continuous operation with 4 d of hydraulic retention time and mean cell residence time of 6.75 d in a photo-bioreactor (PBR) with varying P availability. The fed-batch condition showed that P concentrations of 3-4 mg L-1 were effective for photosynthetic chl. a development in iron flocculated conditions. In the PBR, the oxygen evolution rate increased with increase in the concentration of MAAS (from 258 to 573 mg TSS L-1) at higher surface photosynthetic active radiation (250 and 500 µmol m-2 s-1). Additionally, the rate approached a saturation phase at low MAAS (110 mg L-1) with higher light intensities. Semi-continuous operation with luxury P uptake and effective P condition showed stable average total nitrogen removal of 88 and 92% respectively, with residual concentrations of 3.77 and 2.21 mg L-1. The corresponding average P removal was 68 and 59% with residual concentrations of 2.32 and 1.75 mg L-1. The semi-continuous operation produced a rapidly settleable MAAS under iron flocculated condition with a settling velocity of 92-106 m h-1 and sludge volume index of 31-43 ml g-1 in the studied cases.

Influence of hydraulic retention time on indigenous microalgae and activated sludge process.

Integration of the microalgae and activated sludge (MAAS) process in municipal wastewater treatment and biogas production from recovered MAAS was investigated by studying the hydraulic retention time (HRT) of semi-continuous photo-bioreactors. An average total nitrogen (TN) removal efficiency (RE) of maximum 81.5 ± 5.1 and 64.6 ± 16.2% was achieved at 6 and 4 days HRT. RE of total phosphorous (TP) increased slightly at 6 days (80 ± 12%) HRT and stabilized at 4 days (56 ± 5%) and 2 days (55.5 ± 5.5%) HRT due to the fluctuations in COD and N/P mass ratio of the periodic wastewater. COD and organic carbon were removed efficiently and a rapidly settleable MAAS with a sludge volume index (SVI_10) of less than 117 mL g(-1) was observed at all HRTs. The anaerobic digestion of the untreated MAAS showed a higher biogas yield of 349 ± 10 mL g VS(-1) with 2 days HRT due to a low solids retention time (SRT). Thermal pretreatment of the MAAS (120 °C, 120 min) did not show any improvement with biogas production at 6 days (269 ± 3 (untreated) and 266 ± 16 (treated) mL gVS(-1)), 4 days (258 ± 11(untreated) and 263 ± 10 (treated) mL gVS(-1)) and 2 days (308 ± 19 mL (treated) gVS(-1)) HRT. Hence, the biogas potential tests showed that the untreated MAAS was a feasible substrate for biogas production. Results from this proof of concept support the application of MAAS in wastewater treatment for Swedish conditions to reduce aeration, precipitation chemicals and CO2 emissions.

Steady state protein levels in Geobacter metallireducens grown with iron (III) citrate or nitrate as terminal electron acceptor.

Geobacter species predominate in aquatic sediments and submerged soils where organic carbon sources are oxidized with the reduction of Fe(III). The natural occurrence of Geobacter in some waste sites suggests this microorganism could be useful for bioremediation if growth and metabolic activity can be regulated. 2-DE was used to monitor the steady state protein levels of Geobacter metallireducens grown with either Fe(III) citrate or nitrate to elucidate metabolic differences in response to different terminal electron acceptors present in natural environments populated by Geobacter. Forty-six protein spots varied significantly in abundance (p<0.05) between the two growth conditions; proteins were identified by tryptic peptide mass and peptide sequence determined by MS/MS. Enzymes involved in pyruvate metabolism and the tricarboxylic acid (TCA) cycle were more abundant in cells grown with Fe(III) citrate, while proteins associated with nitrate metabolism and sensing cellular redox status along with several proteins of unknown function were more abundant in cells grown with nitrate. These results indicate a higher level of flux through the TCA cycle in the presence of Fe(III) compared to nitrate. The oxidative stress response observed in previous studies of Geobacter sulfurreducens grown with Fe(III) citrate was not seen in G. metallireducens.

Detection of in situ derivatized peptides in microbial biofilms by laser desorption 7.87 eV postionizaton mass spectrometry.

A novel analytical method based on laser desorption postionization mass spectrometry (LDPI-MS) was developed to investigate the competence and sporulation factor-a pentapeptide of amino acid sequence ERGMT-within intact Bacillus subtilis biofilms. Derivatization of the neat ERGMT peptide with quinoline- and anthracene-based tags was separately used to lower the peptide ionization potential and permit direct ionization by 7.87-eV vacuum ultraviolet radiation. The techniques of mass shifting and selective ionization of the derivatized peptide were combined here to permit detection of ERGMT peptide within intact biofilms by LDPI-MS, without any prior extraction or chromatographic separation. Finally, imaging MS specific to the derivatized peptide was demonstrated on an intact biofilm using LDPI-MS. The presence of ERGMT in the biofilms was verified by bulk extraction/LC-MS. However, MALDI imaging MS analyses were unable to detect ERGMT within intact biofilms.