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Biomedical subjects

Jill Erickson

Publications and source records attributed to Jill Erickson.

9 recordsLinked to original sources
PubMed2006

Intramedullary total femoral replacement for salvage of the compromised femur associated with hip and knee arthroplasty.

Severely compromised femora because of prosthetic loosening, osteolysis, or periprosthetic fracture around total hip and knee arthroplasties are increasing. Two approaches that create an intramedullary total femoral (IMTF) replacement are reported. Twenty-three IMTF replacements in 22 patients were performed at 2 institutions. Seven revision total knee arthroplasties with a stemmed component were linked to a well-fixed hip stem with a custom intramedullary sleeve. Sixteen IMTF replacements involved revision of both hip and knee arthroplasties which were connected via an intercalary segment with morse taper junctions. Follow-up averaged 36 months. Complications included 2 dislocations, 2 deep infections, and 2 knee revisions for tibial loosening. Advantages over conventional total femoral replacement or ORIF include less dissection, maintenance of soft tissue attachments, and immediate component stability to allow for early mobilization.

Aged↗
PubMed2006

The effect of a new multimodal perioperative anesthetic regimen on postoperative pain, side effects, rehabilitation, and length of hospital stay after total joint arthroplasty.

This study evaluated the effect of a new multimodal perioperative anesthetic and pain management strategy for primary total hip (THA) and total knee arthroplasty (TKA). Two cohorts of 50 consecutive THA and 50 TKA patients from before and after initiation of the new protocol were compared. The protocol involved scheduled oral narcotics, cyclooxygenase-2 inhibitors, no intrathecal narcotics, femoral nerve catheters for TKAs, and local anesthetic wound infiltration. Use of patient-controlled analgesia was discouraged. Physical therapy was attempted on the day of surgery. The demographic data, surgical procedure, and implants were similar. There were statistically significant improvements after the protocol regarding rest-pain scores post-operative day (POD) 1 and 2, total narcotic consumption, distance walked POD 1 and 2, and length of stay. There were no significant differences in complications. Implementation of this new multimodal perioperative protocol combined with early mobilization for TKA and THA patients has shortened length of stay, improved pain control, and accomplished therapy goals sooner with less narcotic consumption.

Anesthesia, Epidural↗
PubMed2005

Revision total knee arthroplasty with modular components inserted with metaphyseal cement and stems without cement.

The clinical and radiographic outcomes of 50 consecutive revision total knee arthroplasties in 47 patients, placed with metaphyseal cemented femoral and tibial components with press-fit cementless stems, were reviewed at 36-month average follow-up. Revision was performed for aseptic loosening (11/50), infection (17/50), periprosthetic fracture (8/50), component failure (6/50), instability (6/50), and malalignment (2/50). The press-fit cementless stems were 80 to 160 mm in length and tightly contacted the endosteum of the metadiaphyseal areas. Four (9%) knees were re-revised for infection, zero for aseptic loosening. The average modified Hospital for Special Surgery knee score improved from 49 to 87. One patient (2%) reported thigh pain, and 1 reported leg pain. Metaphyseal cemented revision total knee components with press-fit cementless femoral and tibial stems were not associated with significant thigh and leg pain.

Adult↗
PubMed2005

Heterologous expression of hexaheme fragments of a multidomain cytochrome from Geobacter sulfurreducens representing a novel class of cytochromes c.

Multiheme cytochromes c are of great interest for researchers for a variety of reasons but difficult to obtain in quantities sufficient for the majority of studies. The genome of delta-proteobacterium Geobacter sulfurreducens contains more than a hundred genes coding for c-type cytochromes. Three of them represent a new class of multiheme cytochromes characterized by a mixed type of heme coordination and multidomain organization. We cloned and expressed in Escherichia coli three hexaheme fragments corresponding to two-domain fragments of one such protein containing 12 heme binding motifs and believed to consist of four triheme domains. Despite high sequence similarity among the fragments, expression levels varied significantly. Expression was optimized either by host strain variation or by reducing the rate of apoprotein synthesis. All three fragments were purified by cation exchange followed by gel filtration and were shown to contain six covalently attached hemes as confirmed by mass spectrometry. Their visible spectra are typical of c-type cytochromes. One of the fragments was crystallized and its preliminary X-ray structure shows two separate domains.

Amino Acid Sequence↗
PubMed2004

Redox characterization of Geobacter sulfurreducens cytochrome c7: physiological relevance of the conserved residue F15 probed by site-specific mutagenesis.

The complete genome sequence of the delta-proteobacterium Geobacter sulfurreducens reveals a large abundance of multiheme cytochromes. Cytochrome c(7), isolated from this metal ion-reducing bacterium, is a triheme periplasmic electron-transfer protein with M(r) 9.6 kDa. This protein is involved in metal ion-reducing pathways and shares 56% sequence identity with a triheme cytochrome isolated from the closely related delta-proteobacterium Desulfuromonas acetoxidans (Dac(7)). In this work, two-dimensional NMR was used to monitor the heme core and the general folding in solution of the G. sulfurreducens triheme cytochrome c(7) (PpcA). NMR signals obtained for the three hemes of PpcA at different stages of oxidation were cross-assigned to the crystal structure [Pokkuluri, P. R., Londer, Y. Y., Duke, N. E. C., Long, W. C., and Schiffer, M. (2004) Biochemistry 43, 849-859] using the complete network of chemical exchange connectivities, and the order in which each heme becomes oxidized was determined at pH 6.0 and 8.2. Redox titrations followed by visible spectroscopy were also performed in order to monitor the macroscopic redox behavior of PpcA. The results obtained showed that PpcA and Dac(7) have different redox properties: (i) the order in which each heme becomes oxidized is different; (ii) the reduction potentials of the heme groups and the global redox behavior of PpcA are pH dependent (redox-Bohr effect) in the physiological pH range, which is not observed with Dac(7). The differences observed in the redox behavior of PpcA and Dac(7) may account for the different functions of these proteins and constitute an excellent example of how homologous proteins can perform different physiological functions. The redox titrations followed by visible spectroscopy of PpcA and two mutants of the conserved residue F15 (PpcAF15Y and PpcAF15W) lead to the conclusion that F15 modulates the redox behavior of PpcA, thus having an important physiological role.

Amino Acid Substitution↗
PubMed2004

Structure of a novel c7-type three-heme cytochrome domain from a multidomain cytochrome c polymer.

The structure of a novel c(7)-type cytochrome domain that has two bishistidine coordinated hemes and one heme with histidine, methionine coordination (where the sixth ligand is a methionine residue) was determined at 1.7 A resolution. This domain is a representative of domains that form three polymers encoded by the Geobacter sulfurreducens genome. Two of these polymers consist of four and one protein of nine c(7)-type domains with a total of 12 and 27 hemes, respectively. Four individual domains (termed A, B, C, and D) from one such multiheme cytochrome c (ORF03300) were cloned and expressed in Escherichia coli. The domain C produced diffraction quality crystals from 2.4 M sodium malonate (pH 7). The structure was solved by MAD method and refined to an R-factor of 19.5% and R-free of 21.8%. Unlike the two c(7) molecules with known structures, one from G. sulfurreducens (PpcA) and one from Desulfuromonas acetoxidans where all three hemes are bishistidine coordinated, this domain contains a heme which is coordinated by a methionine and a histidine residue. As a result, the corresponding heme could have a higher potential than the other two hemes. The apparent midpoint reduction potential, E(app), of domain C is -105 mV, 50 mV higher than that of PpcA.

Amino Acid Sequence↗
PubMed2004

Reconstruction of the medial femoral condyle and medial collateral ligament in total knee arthroplasty using tendoachilles allograft with a calcaneal bone block.

Absence or compromise of the medial collateral ligament (MCL) in conjunction with osseous defects of the medial femoral condyle in total knee arthroplasty (TKA) is a challenging reconstructive problem. Treatment usually requires a highly constrained TKA with or without ligamentous reconstruction. To restore the medial femoral condylar bone and to provide ligamentous stability on the medial side of the knee, the authors present a technique for reconstruction of the medial femoral condyle and MCL using a tendoachilles allograft with a calcaneal bone block. The construct also can be augmented with a semitendinosus tendon autograft. Two illustrative cases and a review of the literature are presented.

Achilles Tendon↗
PubMed2004

Acetabular revision with a modular anti-protrusio acetabular component.

Current anti-protrusio cages are non-porous-coated and 1 piece and they require liner cementation. These factors limit bone ingrowth, trials, and modularity. Results of a completely modular porous-coated anti-protrusio component (MAPC) are presented. Sixty-three acetabular revisions with MAPC were performed from 1998-2001 by 2 surgeons. Average follow-up was 29 months (range, 24-50). 30/63 (48%) had Paprosky type 3A or B defects. 55/63 (87%) MAPCs remain in place. Four components were removed for infection, 3 for loosening, and 1 for malposition. Eight hips dislocated, requiring 6 reoperations. Two MAPCs are radiographically loose but asymptomatic. At short-term follow-up, these results are comparable to conventional 1-piece anti-protrusio cages. Advantages include the potential for bone ingrowth and long-term fixation, surgical technique similar to large hemispherical components, ability to trial, and modularity.

Acetabulum↗