Thermal expansion modular femoral head extractor for revision total hip arthroplasty

Removal of a prosthetic modular femoral head is sometimes desirable during revision hip arthroplasty. A femoral head extractor was designed to heat and expand the prosthetic femoral head, apply a gentle distraction load, and remove the femoral head without injury to the femoral neck, taper, or bone-prosthesis interface. The device was used clinically in six hip revision cases. In five hips with cobalt-chrome heads and titanium alloy tapers, femoral heads were removed successfully; femoral fixation was maintained and femoral components were not visibly damaged. In the sixth case, the female portion of the taper junction was contained in a long femoral head sleeve. Heating the ball did not adequately expand the sleeve to allow easy ball removal.     

Inner ear perfusion and the role of round window patency

OBJECTIVE: To report two cases of seizures associated with the use of muromonab-CD3. CASE SUMMARY: Two uremic cadaveric kidney transplant recipients had developed generalized seizures following administration of muromonab-CD3 within the first 2 days after transplantation. Seizures were treated successfully with intravenous phenytoin, and muromonab-CD3 administration was discontinued. DISCUSSION: The overall frequency of seizures during muromonab-CD3 administration is 6%. Uremia in patients in the early posttransplant period appears to predispose them to seizures. Seizures that happened to our two uremic patients after transplant suggest that they had been induced by muromonab-CD3 administration. The mechanism of how this could have induced seizures is unknown. CONCLUSIONS: Prophylactic muromonab-CD3 should be used carefully in uremic kidney transplant recipients following surgery. If therapy with muromonab-CD3 is necessary early hemodialysis should be considered in an effort to lower the risk of seizures.     

Visual immunoprecipitate assay (VIP) for detection of enterohemorrhagic Escherichia coli (EHEC) O157:H7 in selected foods: collaborative study

Protein transport in eukaryotic cells requires the selective docking and fusion of transport intermediates with the appropriate target membrane. t-SNARE molecules that are associated with distinct intracellular compartments may serve as receptors for transport vesicle docking and membrane fusion through interactions with specific v-SNARE molecules on vesicle membranes, providing the inherent specificity of these reactions. VAM3 encodes a 283-amino acid protein that shares homology with the syntaxin family of t-SNARE molecules. Polyclonal antiserum raised against Vam3p recognized a 35-kD protein that was associated with vacuolar membranes by subcellular fractionation. Null mutants of vam3 exhibited defects in the maturation of multiple vacuolar proteins and contained numerous aberrant membrane-enclosed compartments. To study the primary function of Vam3p, a temperature-sensitive allele of vam3 was generated (vam3(tsf)). Upon shifting the vam3(tsf) mutant cells to nonpermissive temperature, an immediate block in protein transport through two distinct biosynthetic routes to the vacuole was observed: transport via both the carboxypeptidase Y pathway and the alkaline phosphatase pathway was inhibited. In addition, vam3(tsf) cells also exhibited defects in autophagy. Both the delivery of aminopeptidase I and the docking/ fusion of autophagosomes with the vacuole were defective at high temperature. Upon temperature shift, vam3(tsf) cells accumulated novel membrane compartments, including multivesicular bodies, which may represent blocked transport intermediates. Genetic interactions between VAM3 and a SEC1 family member, VPS33, suggest the two proteins may act together to direct the docking and/or fusion of multiple transport intermediates with the vacuole. Thus, Vam3p appears to function as a multispecificity receptor in heterotypic membrane docking and fusion reactions with the vacuole. Surprisingly, we also found that overexpression of the endosomal t-SNARE, Pep12p, suppressed vam3Delta mutant phenotypes and, likewise, overexpression of Vam3p suppressed the pep12Delta mutant phenotypes. This result indicated that SNAREs alone do not define the specificity of vesicle docking reactions.     

Clustered p53 immunostaining: a novel pattern associated with prostate cancer progression

Abnormal p53 protein accumulation is typically defined as present when greater than 5 or 10% of cancer cells stain positively. We present a novel approach whereby immunopositivity is defined when 15 or more cells within a 300 x 400-micrometer(2) field exhibit p53 protein accumulation; a feature that we have called "clustered" staining. We assessed p53 immunostaining of moderately differentiated, clinically localized prostate cancers derived from two patient groups: those without cancer recurrence 5 years after radical prostatectomy, and those in whom cancer had recurred following radical prostatectomy. Clustered p53 immunopositivity was present in 10 (63%) of 16 patients in the recurrent group and in only 7 (21%) of 33 in the nonrecurrent group. Clustered p53 staining was clearly associated with cancer recurrence (P < 0.01). This refinement of a commonly used assay may help define the biological aggressiveness of a cancer.     

Thiol ester hydrolysis catalyzed by glutathione S-transferase A1-1

rGSTA1-1 has been shown to catalyze the hydrolysis of the thiol ester glutathionyl ethacrynate (E-SG). In contrast, neither the retro-Michael addition with the substrate EA-SG, to yield GSH and ethacrynic acid (EA), nor the conjugation reaction between GSH and EA to yield the thiol ester E-SG was catalyzed to any measurable extent under similar conditions. The steady state kcat and KM for hydrolysis of E-SG by wild type rGSTA1-1 were 0.11 +/- 0.009 min-1 and 15.7 +/- 1.6 mM, respectively. The site-directed mutant, Y9F, in which the catalytic Tyr-9 is substituted with Phe, was completely inactive in this reaction. To uncover a mechanistic signature that would distinguish between direct hydrolysis and covalent catalysis involving acylation of Tyr-9, solvent isotope exchange and mass spectrometry experiments were performed. No 18O incorporation into the starting thiol ester was detected with initial velocity solvent isotope exchange experiments. However, covalent adducts corresponding to acylated protein also were not observed by electrospray ionization mass spectrometry, even with an assay that minimized the experimental dead time and which allowed for detection of N-acetyltyrosine acylated with EA in a chemical model system. The kon and koff rate constants for association and dissociation of E-SG were determined, by stopped flow fluorescence, to be 5 x 10(5) s-1 M-1 and 6.7 s-1, respectively. Together with the isotope partitioning results, these rate constants were used to construct partial free energy profiles for the GST-catalyzed hydrolysis of E-SG, assuming that Tyr-9 acts as a general acid-base catalyst. The "one-way flux" of the thiol esterase reaction results directly from the thermodynamic stability of the products after rate-limiting attack of the thiol ester by H2O or Tyr-9, and is sufficient to drive the hydrolysis to completion, in contrast to GST-catalyzed breakdown of other GSH conjugates.     

Biaxial monotonic and fatigue fracture of some commercial ABS and PVC sheets

Biaxial loading of pre-cracked cruciform testpieces has been preformed in a novel rig attached to a uniaxial testing machine. Fracture toughness R or c of the ductile acrylonitride butadiene styrene (ABS) and polyvinyl chloride (PVC) determined by the Cotterell–Mai method is dependent on remote biaxiality. Least toughness is shown for equibiaxial tension; greatest for uniaxial tension. These monotonic fracture results may be modelled using void growth mechanics. Fatigue crack growth rates also depend on remote biaxiality. Paris/Walker representation of the data shows that the slopes n of log (da/dN) versus log K do not change much, but the constant of proportionality C decreases as the tensile mean stress increases. There may be a connection between the biaxial-dependent C and R or c. © 1998 Kluwer Academic Publishers     

用于县本地电话网的交换设备

本文介绍了用于县本地电话网交换设备的主要技术要求,给出了邮电部批准入网的此类设备的主要机型,并指出其发展趋势。     

多媒体通信技术

多媒体通信技术综合了通信和计算机以及网络领域的许多高新技术,是目前世界各界共同关心的热门话题。本文就多媒体通信技术的定义,多媒体通信系统的特征、关键技术、系统构成、设备功能等方面给出较为详尽的论述。