Biomechanical evaluation of the impact of collared cementless total hip arthroplasty stems on implant subsidence: a cadaveric study in German Shepherd.

Background: With the increasing use of cementless total hip arthroplasty (THA), stem subsidence has emerged as one of the primary complications. Although electron beam melting (EBM)-manufactured stems have been demonstrated to prevent subsidence, there has been limited investigation into the comparative biomechanical impact of collarless and collared EBM cementless stems on stem subsidence in veterinary medicine. Aims: This study aimed to compare the stem implant resistance and failure mechanical properties between collarless and collared EBM-manufactured stems. Methods: Seven pairs of femurs were harvested from canine cadavers. In each pair of femurs, the left femur was implanted with a collarless, and the right femur with a same-sized collared cementless stem. Specimen constructs were mounted to the loading frame of a testing machine and load was transferred to the femoral stem parallel to the longitudinal axis of the femur until the stem subsided 5 mm. Load and stem displacement data acquired during the tests were used to generate load-displacement curves and obtain stiffness, yield, and failure data for each specimen construct. Yield and failure energies were calculated as the areas under the load-displacement curves to the respective points. The effects of implant type and load during subsidence were analyzed using paired t-tests. Results: The yield and failure loads for the collared stems were approximately 40% greater than for the collarless stems (156.39 ± 43.63 kgf vs. 112.01 ± 59.83 kgf, P<0.05). Conclusion: This study supported the advantages of collared EBM stems, including subsidence prevention and better initial stability for early osteointegration.

Multi-level anomalous Hall resistance in a single Hall cross for the applications of neuromorphic device.

We demonstrate the process of obtaining memristive multi-states Hall resistance (RH) change in a single Hall cross (SHC) structure. Otherwise, the working mechanism successfully mimics the behavior of biological neural systems. The motion of domain wall (DW) in the SHC was used to control the ascend (or descend) of the RH amplitude. The primary synaptic functions such as long-term potentiation (LTP), long-term depression (LTD), and spike-time-dependent plasticity (STDP) could then be emulated by regulating RH. Applied programmable magnetic field pulses are in varying conditions such as intensity and duration to adjust RH. These results show that analog readings of DW movement can be closely resembled with the change of synaptic weight and have great potentials for bioinspired neuromorphic computing.

Investigation of structural transition of dsDNA on various substrates studied by atomic force microscopy.

Structural transition of single dsDNA molecule which is immobilized on 3-aminopropyltriethoxysilane (APTES) treated substrate (APTES/substrate) or alkylthiol treated substrate (alkylthiol/substrate) has been investigated by atomic force microscopy (AFM). The obtained force versus distance (F-D) curves are used to dissect the transition from B-form to S-form, the melting from double stranded (ds) to single stranded (ss) DNA, and its Young's modulus as well as persistence length. The melt from dsDNA to ssDNA is evidenced by fitting with freely jointed chain (FJC) model. FJC fit and Young's modulus or persistence length values when the molecules are fixed on alkylthiol/substrate are more agreeable with other studies than those on APTES. We have clarified the different results of those experiments by analyzing the binding force between DNA molecules and APTES or alkylthiol linkers on the substrate. The DNA binding to APTES linker is much stronger than that on alkylthiol/substrate.

Emergency recognition system based on multimodal information.

This paper aims to propose an emergency recognition system using multimodal information extracted by an image processing module, a voice processing module, and a gravity sensor processing module. Each processing module detects predefined events such as moving, stopping, fainting, and transfer them to the multimodal integration module. Multimodal integration module recognizes emergency situation by using the transferred events and rechecks it by asking the user some question and recognizing the answer. The experiment was conducted for a faint motion in the living room and bathroom. The results of the experiment show that the proposed system is robust than previous methods and effectively recognizes emergency situations at various situations.

Changes in ultraweak photon emission and heart rate variability of epinephrine-injected rats.

Ultraweak photons which are spontaneously emitted from a living body may be applicable as a non-invasive tool to characterize the physiological state of the living body. We investigated changes in the intensity of ultraweak photon emission, body temperature and the cardiovascular autonomic activity induced by epinephrine injection to rats. A high dose of epinephrine can make changes to the cardiovascular autonomic activity or body temperature. Photon emission of the dorsal part, rectal temperature and heart rate variability (HRV) were measured from eight Sprague-Dawley rats. The intensities of photon emissions for saline injections, which were used as a control, decreased from 13042+/-71 counts/min at the start of measurements to 8709+/-915 counts/min at 1 h after the injections. In the case with epinephrine injections, the intensity of photon emission reduced slowly from 13361+/-354 counts/min to 11040+/-433 counts/min. Rectal temperature increased in both saline- and epinephrine-injected rats, but one hour after the injections the temperature in the epinephrine case was slightly higher than that in the saline case. The standard deviation of the QRS wave complex interval (RR interval) increased from 1 to 4 (p<0.05) and the spectral ratio of the low frequency component to the high frequency component in the HRV data LF (0.19 approximately 0.74 Hz) / HF (0.78 approximately 2.50 Hz) decreased from 0.81 to 0.26 (p<0.05) in the case of epinephrine injection while no change was found in the case of saline injection. Thus, ultraweak photon emission was closely related to the cardiovascular autonomic activity.

Effect of ultrasound on oil removal from soils.

The soil-flushing method enhanced by ultrasonic waves is a new technique that potentially can become an effective method for in situ remediation of the ground contaminated by NAPL hydrocarbons. This study investigated the effectiveness of ultrasound enhancement in the soil-flushing method for a range of conditions involving soil type, soil density, flushing rate, and sonication power. The study was conducted in the laboratory using specially designed and fabricated equipment. The test results indicated that the rate of contaminant extraction increased considerably with increasing sonication power up to the level where cavitation occurred. The effectiveness of sonication-enhanced soil-flushing can be expressed as a function of (D(10))(2)*i, in which D(10) is the effective grain size, and i is the hydraulic gradient.

Effects of presurgical and post-surgical irradiation on the healing process of Medpor in dogs.

The purpose of this study was to determine the effect of irradiation on the healing process and the effect on the contact surface of Medpor and bone. Eighteen dogs were studied. The animals were divided into three groups. Six non-irradiated dogs served as controls (Group 1). Twelve dogs irradiated on the left femur, before and after implantation of Medpor, were studied. The dogs were euthanized 4 and 8 weeks after Medpor was implanted in presurgical irradiation subgroup animals (Group 2) and after the completion of irradiation in post-surgical irradiation subgroup animals (Group 3). Light microscopic and scanning electron microscopic examinations were performed. The appearance of osteoblasts and bone matrix formation were remarkably late and manifest slight reactions in post-surgical irradiation group compared to the control group presenting the osteoblasts at 4 weeks, and those osteoblasts were not visible in presurgical irradiation group in both the 4-week and 8-week observation. We concluded that the bone remodeling was delayed in the irradiated bone, especially in the presurgical group.

Testosterone 5 alpha-reductase inhibitors, menaquinone 7 produced by a Bacillus and phenazine methosulfate.

Menaquinone 7 (MW: 649, C46H64O2), a natural electron acceptor for steroid ring A dehydrogenations, produced by Bacillus sp. SNU-299, was isolated as a rat prostate testosterone 5 alpha-reductase inhibitor with an IC50 value of 4.0 x 10(-5) M from the cultured broth. Phylloquinone was as active as the purified microbial metabolite with an IC50 value of 6.6 x 10(-4) M. On the basis of this evidence, the inhibitory activities of electron carriers, menadione, phenazine methosulfate, and 2,6-dichlorophenolindophenol, for rat prostate testosterone 5 alpha-reductase were tested, and the IC50 values were 3.1 x 10(-6) M, 4.9 x 10(-8) M, 8.9 x 10(-5) M, respectively. A product of the 5 alpha-reductase enzyme reaction and an electron and proton carrier, NADP+, inhibited the 5 alpha-reduction by rat prostate testosterone 5 alpha-reductase with an IC50 value of 9.2 x 10(-5) M. However, the inhibition effect of a proton carrier, carbonylcyanide-m-chlorophenylhydrazone, for rat prostate testosterone 5 alpha-reductase was substantially inactive.

Ca2+-mediated activation of c-Jun N-terminal kinase and nuclear factor kappa B by NMDA in cortical cell cultures.

We examined the possibility that c-Jun N-terminal kinase (JNK) and nuclear factor kappaB (NF-kappaB) might be involved in intracellular signaling cascades that mediate NMDA-initiated neuronal events. Exposure of cortical neurons to 100 microM NMDA induced activation of JNK within 1 min. Activity of JNK was further increased over the next 5 min and then declined by 30 min. Similarly, ionomycin, a selective Ca2+ ionophore, induced activation of JNK. The NMDA-induced activation of JNK was abrogated in the absence of extracellular Ca2+, suggesting that Ca2+ entry is necessary and sufficient for the JNK activation. Immunohistochemistry with anti-NF-kappaB antibody demonstrated nuclear translocation of NF-kappaB within 5 min following NMDA treatment. NMDA treatment also enhanced the DNA binding activity of nuclear NF-kappaB in a Ca2+-dependent manner. Treatment with 3 mM aspirin blocked the NMDA-induced activation of JNK and NF-kappaB. Neuronal death following a brief exposure to 100 microM NMDA was Ca2+ dependent and attenuated by addition of aspirin or sodium salicylate. The present study suggests that Ca2+ influx is required for NMDA-induced activation of JNK and NF-kappaB as well as NMDA neurotoxicity. This study also implies that aspirin may exert its neuroprotective action against NMDA through blocking the NMDA-induced activation of NF-kappaB and JNK.

Binding of a protein to an AU-rich domain of tumour necrosis factor alpha mRNA as a 35 kDa complex and its regulation in primary rat astrocytes.

Newcastle disease virus (NDV) induces tumour necrosis factor alpha (TNF alpha) gene transcription and increases the mRNA stability. NDV stabilizes TNF alpha mRNA by preventing poly(A) shortening in a protein kinase C-dependent manner. TNF alpha 3'-untranslated region (UTR) contains an AU-rich domain (ARD) with seven AUUUA pentamers, a motif implicated in poly(A) removal and mRNA degradation. In this report, protein binding to TNF alpha ARD and the effects of NDV and kinases on ARD-binding activity were investigated in primary rat astrocytes. Both nuclear and cytoplasmic extracts contained proteins binding to centrally located 27 nt AUUUAUUAUUUAUUUAUUAUUUAUUUA, within TNF alpha ARD. Portions of ARD with a single AUUUA did not show ARD-binding activity. The ARD-protein complexes migrated as two bands on electrophoretic mobility-shift assay. The slower moving complexes appeared either as a broader band or doublets. The UV cross-linked ARD-protein complexes, however, migrated as a single 35 kDa band on SDS/PAGE. In cytoplasmic extracts treated with alkaline phosphatase there was a decrease in the faster moving complex and an increase in the slower moving complex, whereas NDV infection produced the reverse effect. In addition, the faster moving complex was decreased when cytoplasmic extracts from NDV-infected cells were treated with protein phosphatase 1 or 2A. Neither NDV infection nor phosphatase treatment affected the mobility pattern of nuclear extracts. The data indicate that a protein of molecular mass less than 35 kDa binds to a segment of TNF alpha ARD containing primarily UUAUUUAUU motifs, and the ARD-binding activity in cytoplasmic compartment is post-transcriptionally modified.

Mouse complement regulatory protein Crry/p65 uses the specific mechanisms of both human decay-accelerating factor and membrane cofactor protein.

Normal host cells are protected from the destructive action of complement by cell surface complement regulatory proteins. In humans, decay-accelerating factor (DAF) and membrane cofactor protein (MCP) play such a biologic role by inhibiting C3 and C5 convertases. DAF and MCP accomplish this task by specific mechanisms designated decay-accelerating activity and factor I cofactor activity, respectively. In other species, including mice, structural and/or functional homologues of these proteins are not yet well characterized. Previous studies have shown that the mouse protein Crry/p65 has certain characteristics of self-protecting complement regulatory proteins. For example, Crry/p65 is expressed on a wide variety of murine cells, and when expressed on human K562 erythroleukemic cells, it prevents deposition of mouse C3 fragments on the cell surface during activation of either the classical or alternative complement pathway. We have now studied factor I cofactor and decay-accelerating activities of Crry/p65. Recombinant Crry/p65 demonstrates cofactor activity for factor I-mediated cleavage of both mouse C3b and C4b. Surprisingly, Crry/p65 also exhibits decay-accelerating activity for the classical pathway C3 convertase strongly and for the alternative pathway C3 convertase weakly. Therefore, mouse Crry/p65 uses the specific mechanisms of both human MCP and DAF. Although Crry/p65, like MCP and DAF, contains tandem short consensus repeats (SCR) characteristic of C3/C4 binding proteins, Crry/p65 is not considered to be a genetic homologue of either MCP or DAF. Thus, Crry/p65 is an example of evolutionary conservation of two specific activities in a single unique protein in one species that are dispersed to individual proteins in another. We propose that the repeating SCR motif in this family has allowed this unusual process of evolution to occur, perhaps driven by the use of MCP and DAF as receptors by human pathogens such as the measles virus.

Tyrosine kinase activation by Newcastle disease virus is required for TNF-alpha gene induction in astrocytes.

Astrocytes, when appropriately stimulated, produce a variety of cytokines including TNF-alpha. Production of TNF-alpha by astrocytes stimulated with Newcastle disease virus (NDV) is achieved by transcriptional activation and mRNA stabilization. A PKC-dependent pathway is responsible for a 10-fold increase in TNF-alpha mRNA stability by reducing poly(A) tail removal. The present study examined signal pathways induced by NDV in primary rat astrocytes that are responsible for TNF-alpha gene transcription as well as the possible source of kinase activity required for mRNA stabilization. Transcription of TNF-alpha gene in astrocytes stimulated by NDV or LPS and IFN-gamma was inhibited completely by the tyrosine kinase inhibitor herbimycin, and partially by a PKC inhibitor H7, as determined by nuclear run-on assay. HA-1004, a cyclic nucleotide-dependent kinase inhibitor, showed no effect. These results indicated that tyrosine kinase signaling pathways seemed to precede the activation of PKC in induction of TNF-alpha gene. Increase in tyrosine kinase activity in NDV-infected astrocytes was demonstrated by a two- to threefold increase in tyrosine phosphorylation of Pl-PLC gamma 1. Because astrocytes contain minimal Pl-PLC beta, and NDV-induced TNF-alpha mRNA was affected by pertussis toxin only modestly, Pl-PLC gamma 1 is likely the enzyme responsible for DAG generation and the PKC-dependent mRNA stabilization in response to NDV.

Ligand specificities of mouse complement receptor types 1 (CR1) and 2 (CR2) purified from spleen cells.

Murine complement receptor type 2 (MCR2) is homologous to human CR2, whereas murine CR1 (MCR1) is structurally and evolutionary different from human CR1. Since ligand specificities of MCR1 and MCR2 are not completely clarified, we analyzed their functional characteristics to correlate them with structural information obtained in molecular biological studies. MCR1 and MCR2 purified from spleen cells were incubated with thiol-Sepharose bearing murine C3b, iC3b, or C3d in the presence or absence of various anti-MCR1 or -MCR1/MCR2 mAbs. Bound and free MCR1 and MCR2 were quantitated by Western blotting or two-site immunoradiometric assay. MCR2 bound to C3d and iC3b similarly efficiently, and 5-fold less efficiently to C3b. These bindings were completely inhibited by MCR1/MCR2-crossreactive antibodies 7G6 and 4E3. MCR1 bound to C3b efficiently and this was partially inhibited by MCR1-monospecific antibody 8C12, but not by 7G6 and 4E3. Combinations of 8C12 and 7G6 or 4E3 completely inhibited MCR1 binding to C3b. Therefore, two binding sites, one unique to MCR1 and the other shared with MCR2, are involved in MCR1 binding to C3b. MCR1 bound also to C3d and this was completely inhibited by 7G6 and 4E3. The binding of this solubilized MCR1 to C3d was as efficient as that of MCR2 to C3d. It seems, therefore, that the site shared by MCR1 and MCR2 that is recognized by both 7G6 and 4E3 binds to C3d and less efficiently to C3b. These results clarify the ligand specificities of MCR1 and MCR2.

Deficient surface expression of glycosylphosphatidylinositol-anchored proteins in B cell lines established from patients with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired type hemolytic disorder. Hematopoietic cells of patients with PNH are deficient in glycosylphosphatidylinositol (GPI) anchored membrane proteins. Since some membrane-bound complement inhibitors, such as CD59 and decay accelerating factor (DAF), are GPI anchored proteins, abnormal cells from patients with PNH are sensitive to complement attack. Their myeloid and erythroid cells are affected more than their lymphoid cells. Patients whose B cells were severely deficient in GPI anchored proteins were chosen to establish cell lines by Epstein-Barr virus mediated transformation. The lines established (SS-1-, TK-1-, and TK-14- cell lines) had the following characteristics of PNH. First, GPI anchored proteins were completely absent from the surface of SS-1- and TK-14- cells, and were expressed at very low levels on TK-1- cells, whereas polypeptide anchored proteins were normally expressed on these three lines. Secondly, DAF mRNAs of the SS-1- cell line were qualitatively and quantitatively indistinguishable from those of a control, wild-type cell line. Third, pro-CD59 and pro-DAF molecules were detected intracellularly in these cell lines, their pro-CD59 being smaller and more hydrophilic than that from a wild-type cell line. These cell lines should be useful in further studies on the pathogenesis of PNH.

Covalent binding of C3b to C4b within the classical complement pathway C5 convertase. Determination of amino acid residues involved in ester linkage formation.

C5 convertase of the classical complement pathway is a protein complex consisting of C4b, C2a, and C3b. Within this complex C3b binds to C4b via an ester linkage. We now present evidence that the covalent C3b-binding site on human C4b is Ser at position 1217 of C4. We also show that formation of the covalently linked C4b.C3b complex occurs in the mouse complement system and that the C3b-binding site on mouse C4b is Ser at position 1213 which is homologous to Ser-1217 of human C4. Therefore, covalent binding of C3b to a single specific site on C4b within the classical pathway C5 convertase is likely a common phenomenon in the mammalian complement system. Specific noncovalent association of metastable C3b with C4b would occur first, leading to reaction of the thioester with a specific hydroxy group. This is supported by two lines of experimental evidence, one which shows that a mutant C4 that does not make a covalent linkage with C3b is still capable of forming C5 convertase and a second in which the C4b.C3b complex has been demonstrated by cross-linking erythrocytes bearing this C5 convertase.

Reconstitution of C5 convertase of the alternative complement pathway with isolated C3b dimer and factors B and D.

C5 convertase of the alternative complement pathway is a trimolecular complex consisting of two molecules of C3b and one molecule of Bb. We previously proposed a model of the alternative pathway C5 convertase in which the second C3b molecule binds covalently to the first C3b molecule bearing Bb, and the C5 molecule binds to each C3b molecule of the covalently linked C3b dimer, resulting in its appropriate presentation to the catalytic site on Bb. In the present study, we purified the covalently linked C3b dimer and reconstituted the C5 convertase with the C3b dimer and factors B and D to obtain evidence in support of this model. An insoluble glucan, OMZ-176, was incubated with human serum to activate the alternative pathway and to allow formation of the alternative C5 convertase on the surface of the glucan, and the glucan bearing the C5 convertase was then solubilized by incubation with glucosidases. In this way, the covalently linked C3b dimer was obtained in solution without using a detergent. The C3b dimer was then separated from enzymes, C3b monomer, C3b oligomer, and other materials by chromatographies. SDS-PAGE analysis demonstrated that the purified C3b dimer had intact alpha'-chains. Alternative pathway C5 convertase was reconstituted when the isolated C3b dimer was incubated with factors B and D. The presence of P enhanced C5 convertase formation threefold. These results support the notions that the formation of the covalently linked C3b dimer is a general phenomenon associated with activation of the alternative pathway and that the C3b dimer acts as a part of the C5 convertase.

Localization of the covalent C3b-binding site on C4b within the complement classical pathway C5 convertase, C4b2a3b.

C5 convertase of the classical complement pathway is a trimolecular protein complex consisting of C4b, C2a, and C3b. In the complex there is an ester bond between C3b and C4b. We analyzed the C5 convertase formed on erythrocytes and localized the covalent binding site of C3b to a small region on C4b. The covalently linked C4b.C3b complex was purified from a detergent extract of the erythrocytes and digested with lysyl endopeptidase. An Mr 17,000 fragment containing the ester linkage between C4b and C3b was purified and its amino-terminal sequence was examined. Two amino acids were obtained at each cycle and identified with those in the sequences of C3 and C4. The sequence derived from C3 corresponded to the thioester region. The sequence derived from C4 started at Ala-1186. Alkali treatment of the fragment yielded an Mr 7,000 peptide derived from C4, which thus appeared to span the region of C4 from Ala-1186 to Lys-1259. Therefore, the covalent C3b-binding site on C4b is located within a 74-residue region of the primary structure. This finding supports the notion that after cleavage of C3 by the C4b2a complex, the covalent binding of metastable C3b to C4b is a specific reaction to form a trimolecular complex with a defined quaternary structure.

Inhibition of the alternative C3 convertase and classical C5 convertase of complement by group A streptococcal M protein.

When Streptococcus pyogenes group A type 3 strain C203 (M+) and its M-protein-lacking derivative, strain C203S (M-), were treated with normal human serum in the presence of magnesium-EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid], virulent M+ bacteria bound only 10 to 30% as much C3 and factors B and P as did avirulent M- bacteria. After treatment of M+ bacteria with trypsin, which inactivates M protein, their binding of these substances was similar to that of M- bacteria. Pretreatment of M+ bacteria with the Fab fragment of rabbit immunoglobulin G anti-M antibody also increased their binding of C3 in the absence of Ca2+. Therefore, M protein inhibits the alternative C3 convertase. In contrast, in the presence of Ca2+ and Mg2+, M+ bacteria bound 75% as much C3 as M- bacteria. This binding was mostly mediated by classical pathway activation, because M+ bacteria bound much smaller amounts of factors B and P than did M- bacteria but consumed amounts of C4 and C2 comparable to those consumed by M- bacteria. On the other hand, the amount of C5 bound to M+ bacteria was much less than that bound to M- bacteria, and the consumption of C5 and C8 by M+ bacteria was also much less than that by M- bacteria. Therefore, M protein does not inhibit the classical C3 convertase but does inhibit the classical C5 convertase. When M+ and M- streptococci were incubated with normal human serum containing radiolabeled C3 in the presence of Ca2+ and Mg2+, more than 85% of the C3 bound to either type of streptococcus was extractable by sodium dodecyl sulfate and alkali treatment. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the C3 extracted from both strains showed that it was mostly C3b and iC3b. The proportions of C3b and iC3b, respectively, were 7.5 and 71.9% on M+ bacteria and 18.9 and 58.4% on M- bacteria. These results support and extend previous findings that the antiphagocytic activity of streptococcal M protein may be due to complement inhibition mediated by the binding of factor H.