Electromyography as a measure of peak and cumulative workload in intermediate care and its relationship to musculoskeletal injury: an exploratory ergonomic study

Injury rates in Intermediate Care (IC) facilities are high and the factors related to these injuries are unclear. The objectives of this exploratory sub-study, which is part of a large multi-faceted study in 8 IC facilities are to: (1) evaluate EMG measured over a full-shift in the back and shoulders of 32 care aides (CAs) as an indicator of peak and cumulative workload (n = 4 x 8 facilities); investigate the relationship between EMG measures and injury indicators; and explore the relationship between EMG measures and other workload measurements. Lumbar EMG was converted to predicted cumulative spinal compression and ranged in CAs from 11.7 to 22.8 MNs with a mean of 16.4 MNs. Average compression was significantly different during different periods of the day (p < 0.001) with highest compression during pre-breakfast when CAs assist most with activities of daily living. Significant differences were found in average compression between low and high injury facilities for 3 of 5 periods of the day (p < 0.010). Peak compressions exceeding 3400 N occurred for very little of the workday (e.g. 11.25s during the 75 min period pre-breakfast). Peak neck/shoulder muscle activity is low (99% APDF ranged from 8.33% to 28% MVC). Peak and cumulative spinal compression were significantly correlated with lost-time and musculoskeletal injury rates as well as with total tasks observed in the CAs (p < 0.01). Perceived exertion was only correlated with peak compressions (p < 0.01). Facilities with low injury rates provided significantly more CAs (p < 0.01) to meet resident needs, and subsequently CAs performed fewer tasks, resulting in less peak and cumulative spinal loading over the day.

Finite element contact stress analysis of the RPD abutment tooth and periodontal ligament

OBJECTIVES

The purpose of this study was to determine the influence of the occlusal rest position in removable partial dentures on the displacement of the abutment tooth and the stress distribution in the periodontal ligament (PL).

METHODS

We constructed three-dimensional finite element models of the mandibular first and second premolars. A layer of the PL and a mesial or distal occlusal rest were produced on the second premolar as an abutment. A zero displacement was prescribed on the outer surface of the PL and the first premolar. In each simulation, the rest was moved 0.05 mm vertically to the apical direction, with or without restriction of horizontal movements. We simulated the contact phenomena on the abutment surfaces, and calculated the movements of the abutment and stress distributions in the PL.

RESULTS

We observed a maximum distal displacement of 42 microm at the buccal cusp of the abutment and a principal compressive stress of 0.35 MPa in the PL when the abutment was vertically loaded by a distal rest that was allowed to move horizontally. However, the displacements and stresses were relatively small, and were all within the physiological limitations of the tissues. The restriction of the horizontal movement of the rests was effective in reducing the horizontal displacements of the abutment, regardless of the rest position.

CONCLUSIONS

The single vertical load exerted from either the mesial or distal rest on the abutment was unlikely to cause any mechanical damage to its supporting tissues.

Work organization and patient care staff injuries: the impact of different care models for "alternate level of care" patients

BACKGROUND

The number of elderly patients who do not have acute-care needs has increased in many North American hospitals. These alternate level care (ALC) patients are often cognitively impaired or physically dependent. The physical and psychosocial demands on caregivers may be growing with the increased presence of ALC patients leading to greater risk for injury among staff.

METHODS

This prospective cohort study characterized several models for ALC care in four acute-care hospitals in British Columbia, Canada. A cohort of 2,854 patient care staff was identified and followed for 6 months. The association between ALC model of care and type and severity of injury was examined using multinomial and ordinal logistic regression.

RESULTS

Regression models demonstrated that the workers on ALC/medical nursing units with "high" ALC patient loads and specialized geriatric assessment units had the greatest risk for injury and the greatest risk for incurring serious injury. Among staff caring for ALC patients, those on dedicated ALC units had the least risk for injury and the least risk for incurring serious injury.

CONCLUSIONS

The way in which ALC care is organized in hospitals affects the risk and severity of injuries among patient care staff.

Purification, characterization, and molecular cloning of a novel amine:pyruvate transaminase from Vibrio fluvialis JS17

A transaminase from Vibrio fluvialis JS17 showing activity toward chiral amines was purified to homogeneity and its enzymatic properties were characterized. The transaminase showed an apparent molecular mass of 100 kDa as determined by gel filtration chromatography and a subunit mass of 50 kDa by MALDI-TOF mass spectrometry, suggesting a dimeric structure. The enzyme had an isoelectric point of 5.4 and its absorption spectrum exhibited maxima at 320 and 405 nm. The optimal pH and temperature for enzyme activity were 9.2 and 37 degrees C, respectively. Pyruvate and pyridoxal 5'-phosphate increased enzyme stability whereas (S)-alpha-methylbenzylamine reversibly inactivated the enzyme. The transaminase gene was cloned from a V. fluvialis JS17 genomic library. The deduced amino acid sequence (453 residues) showed significant homology with omega-amino acid:pyruvate transaminases (omega-APT) from various bacterial strains (80 identical residues with four omega-APTs). However, of 159 conserved residues in the four omega-APTs, 79 were not conserved in the transaminase from V. fluvialis JS17. Taken together with the sequence homology results, and the lack of activity toward beta-alanine (a typical amino donor for the omega-APT), the results suggest that the transaminase is a novel amine:pyruvate transaminase that has not been reported to date.

Anterior cingulotomy for refractory obsessive-compulsive disorder

OBJECTIVE

This study was designed to prospectively investigate the efficacy and cognitive adverse effects of stereotactic bilateral anterior cingulotomy as a treatment for refractory obsessive-compulsive (OCD) patients for 12 months.

METHOD

Patients were eligible if they had severe OCD and rigorous treatments had been unsuccessful. Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Clinical Global Impression (CGI) and neuropsychological tests were used to assess the efficacy and cognitive changes of cingulotomy before and 12 months after operation.

RESULTS

The mean improvement rate of the Y-BOCS scores achieved from baseline was 36.0%. Out of 14 patients six met responder criteria; 35% or higher improvement rate on Y-BOCS and CGI improvement of very much or much better at 12-month follow-up. There was no significant cognitive dysfunction after cingulotomy.

CONCLUSION

Anterior cingulotomy shows few cognitive adverse effects, with about half of the OCD patients demonstrating significant symptomatic improvement.

High bifurcation of median nerve at the wrist causing common digital nerve injury in endoscopic carpal tunnel release

A 45-year-old right-handed woman was treated by endoscopic carpal tunnel release under local anaesthetic. When cutting the proximal half of the flexor retinaculum with the retrograde blade, she complained of an electric shock-like pain in her middle and ring fingers. Open exploration of the carpal tunnel was performed and a laceration of the middle/ring common digital nerve, which bifurcated at the unusually high level of the wrist crease, was found.

Dynamic retentive force of a mandibular unilateral removable partial denture framework with a back-action clasp

PURPOSE

The purpose of this study was to investigate the dynamic retentive force of a mandibular unilateral distal-extension partial denture framework with a back-action clasp that was designed in a buccally tilted cast on a dental surveyor. The retention mechanism of this framework was analyzed in comparison with other typical unilateral and bilateral frameworks for the mandibular Kennedy class II case.

MATERIALS AND METHODS

Experimental gold alloy frameworks of three designs were repositioned to the master cast, and lifted upward to the vertical direction to the occlusal plane. The load required to dislodge each framework was recorded. The retentive force of each framework was determined by the maximum load in a dislodgment cycle. The bending strength of a plain clasp pattern of the same length as the clasp arm used in each framework was also measured by cantilever beam test.

RESULTS

The mean retentive force of the unilateral framework with a back-action clasp of relatively low bending strength was significantly higher (P < 0.01) than that of the unilateral framework with two Akers clasps of relatively high bending strength, and 70 to 80% of the bilateral framework with two Akers clasps on the edentulous side and a double Akers clasp on the contralateral side. The unilateral framework with a back-action clasp showed the greatest early load resistance in the dislodgment cycle among the three designs.

CONCLUSION

The reasonable retention mechanism was demonstrated by the unilateral framework with a back-action clasp.

Identification of a structural motif of 23S rRNA interacting with 5S rRNA

To identify RNA motifs interacting with 5S rRNA, a systematic evolution of ligands by exponential enrichment experiment was applied. Some of the resulting RNA aptamers contained a consensus sequence similar to the sequence in the loop region of helix 89 of 23S rRNA. We show that the synthetic helix 89 RNA motif indeed interacted with 5S rRNA and that the region around loop B of 5S rRNA was involved in this interaction. These results suggest the presence of a novel RNA-RNA interaction between 23S rRNA and 5S rRNA which may play an important role in the ribosome function.

Zinc enhances synthesis of presenilin 1 in mouse primary cortical culture

Whether zinc interacts with presenilin 1 (PS1), one of the causative genes of familial Alzheimer's disease (AD), is not known. Here we report that zinc modulates the synthesis of PS1. Exogenous zinc enhanced the amount of C-terminal fragments of PS1 (PS1-CTF) in neonatal mouse cortical cultures in a dose-dependent manner. Zinc also induced cell death in a dose-dependent manner. These effects of zinc were not mimicked by calcium, copper, or iron, and were blocked by a zinc-specific chelator, TPEN. Experiments using metabolic labeling and cycloheximide treatment revealed that zinc increased PS1-CTF by elevating the de novo synthesis of PS1. Time course experiments revealed that cell death commenced sooner (0.5-1 h) than enhancement of PS1-CTF (1-2 h) following zinc treatment. However, the amount of PS1-CTF remained unchanged during etoposide- or H(2)O(2)-induced cell death, suggesting that enhancement of PS1 synthesis is specifically correlated with zinc-induced cell death.

Rat embryo fibroblasts require both the cell-binding and the heparin-binding domains of fibronectin for survival

Fibronectin (FN) is known to transduce signal(s) to rescue cells from detachment-induced apoptosis (anoikis) through an integrin-mediated survival pathway. However, the functions of individual FN domains have not been studied in detail. In the present study we investigated whether the interaction of the cell-binding domain of FN with integrin is sufficient to rescue rat embryo fibroblasts (REFs) from detachment-induced apoptosis. REFs attached and spread normally after plating on substrates coated with either intact FN or a FN fragment, FN120, that contains the cell-binding domain but lacks the C-terminal heparin-binding domain, HepII. REFs on FN maintained a well-spread fibroblastic shape and even proliferated in serum-free medium at 20 h after plating. In contrast, previously well-spread REFs on FN120 started losing fibroblastic shape with time and detached from FN120-coated plates after approx. 8 h. Nuclear condensation indicated apototic cell death. This was due to the decreased activity/stability of focal adhesion kinase (pp125FAK) in the absence of HepII domain. A peptide in the HepII domain [peptide V, WQPPRARI (single-letter amino acid codes)], which has previously been implicated in cytoskeletal organization, rescued apoptotic changes. Consistently, pp125FAK phosphorylation was increased, and both cleavage of pp125FAK and activation of caspase 3 on FN120 were partly blocked by peptide V. Thus the interaction of the cell-binding domain with integrin has a major role in cell survival but is itself not sufficient for cell survival. One or more additional survival signals come from the HepII domain to regulate pp125FAK activity/stability.

Activity of the APC(Cdh1) form of the anaphase-promoting complex persists until S phase and prevents the premature expression of Cdc20p

Cell cycle progression is driven by waves of cyclin expression coupled with regulated protein degradation. An essential step for initiating mitosis is the inactivation of proteolysis mediated by the anaphase-promoting complex/cyclosome (APC/C) bound to its regulator Cdh1p/Hct1p. Yeast APC(Cdh1) was proposed previously to be inactivated at Start by G1 cyclin/cyclin-dependent kinase (CDK). Here, we demonstrate that in a normal cell cycle APC(Cdh1) is inactivated in a graded manner and is not extinguished until S phase. Complete inactivation of APC(Cdh1) requires S phase cyclins. Further, persistent APC(Cdh1) activity throughout G1 helps to ensure the proper timing of Cdc20p expression. This suggests that S phase cyclins have an important role in allowing the accumulation of mitotic cyclins and further suggests a regulatory loop among S phase cyclins, APC(Cdh1), and APC(Cdc20).

Liquid chromatographic determination of less polar ginsenosides in processed ginseng

Reversed-phase LC with an evaporative light scattering detector (ELSD) is used for the determination of less polar ginsenosides in processed ginseng. These ginsenosides include ginsenosides F4, Rg3, Rg5, Rg6, Rk1, Rk3, Rs3, Rs4, and Rs5. The method used a C18-bonded silica column with a CH3CN/H2O/CH3COOH gradient elution. (20R) and (20S) epimers and geometric isomers at the C-20 position of ginsenosides, which are not generally separated by amino columns, were now clearly separated.

Purification and structural analysis of the hepatitis B virus preS1 expressed from Escherichia coli

The preS1 of hepatitis B virus (HBV) is located at the outermost part of the envelope protein and possesses several functionally important regions such as hepatocyte receptor-binding site and virus-neutralizing epitopes. As the first step to understand the structure-function relationship for the preS1 antigen, we have purified the preS1 and performed its structural characterization by circular dichroism (CD) spectroscopy. The preS1 was purified to near homogeneity from bacterially expressed glutathione S-transferase (GST)-preS1 fusion protein by two-step purification, affinity chromatography on glutathione-agarose column, and cation-exchange chromatography on Mono S column. The CD analysis showed that the purified preS1, which was largely unstructured in aqueous solution, acquired a significant (16%) alpha-helical structure when analyzed in 50% trifluoroethanol or 20 mM SDS. The results suggest that the preS1 assumes a mainly unstructured conformation and may form induced secondary structures upon binding to target proteins or under hydrophobic environment.

Five cases of ocular toxocariasis confirmed by serology

We report 5 cases of ocular toxocariasis in Korean adults complaining of visual impairment along with floating or bubbling sensation. Fundoscopic examination revealed a retinal detachment along with exudate in 4 cases. They all showed typical reaction by ELISA and immunoblot against Toxocra excretory-secretory antigen. One case showed high level of anti-Toxocara IgE antibodies (34,000 Toxocara units/L) as well as increased level of serum total IgE antibodies and the specific IgE antibodies for 3 inhalant antigens, suggesting that high level of anti-Toxocara IgE antibodies was associated with an atopic status. Clinical manifestations were improved after the sequential use of steroids then mebendazole. We also suggest that ocular toxocariasis should be thoroughly investigated even when an evocative uniocular inflammatory lesion is encountered in peripheral retina without a systematic disease.

Tumor suppressor p53 is required to modulate BRCA1 expression

Individuals carrying mutations in BRCA1 or p53 genes are predisposed to a variety of cancers, and both tumor suppressor genes have been implicated in DNA damage response pathways. We have analyzed a possible functional link between p53 and BRCA1 genes. Here we show that BRCA1 expression levels are down-regulated in response to p53 induction in cells that undergo either growth arrest, senescence, or apoptosis. Physiological stimuli, such as exposure to DNA-damaging agents, also result in negative regulation of BRCA1 levels in a p53-dependent manner prior to causing cell cycle arrest. Nuclear run-on experiments and luciferase reporter assays demonstrate that the changes in BRCA1 expression are mainly due to transcriptional repression induced by p53. In conclusion, the data show that BRCA1 expression levels are controlled by the presence and activity of wild-type p53 and suggest the existence of an intracellular p53/BRCA1 pathway in the response of cells to stress conditions.

Cytokines secreted by lymphokine-activated killer cells induce endogenous nitric oxide synthesis and apoptosis in DLD-1 colon cancer cells

IL-2-activated killer lymphocytes (LAK cells) secrete inflammatory cytokines such as interferon-gamma (IFN-gamma) and tumor necrosis factor alpha (TNFalpha) that can induce nitric oxide (NO) synthesis. We evaluated whether LAK cells could activate NO synthesis in human cancer cells. LAK cells and their culture supernatants induced NO synthesis in DLD-1 colon cancer cells in a dose-dependent manner. NO synthesis was inhibited completely by blocking antibodies to IFN-gamma, demonstrating a key role for this LAK cell cytokine in regulating NO synthesis. The addition of TNFalpha antibodies resulted in partial inhibition. Induction of iNOS mRNA and protein expression in DLD-1 cells was detected. Endogenous NO production inhibited DLD-1 cell proliferation and induced apoptosis, processes that were inhibitable by the NO synthase inhibitor N(G)-monomethyl-l-arginine. Our study has identified a novel, non-contact-dependent LAK cell cytotoxic mechanism: induction of growth inhibition and programmed cell death due to endogenous NO synthesis in susceptible human cancer cells.

Translational suppression by hammerhead ribozymes and inactive variants in S. cerevisiae

The activity of hammerhead ribozymes in S. cerevisiae was assessed using two ribozymes that were designed to intramolecularly attack the hepatitis B viral X mRNA. The ribozymes effectively suppressed the expression of the X-lacZ fusion gene, when they were inserted at the 5' end of the X mRNA. The ribozymes cleaved the target RNA efficiently at the targeted phosphodiester bond, but the inactive mutants carrying G5-to-A substitution in the core did not, as the total RNA preparations of yeast extracts was assayed by primer extension. These G5A mutants, however, exerted the suppression as effectively as the wild-type ribozymes. The results, with several mutations introduced to a ribozyme, suggested that either mere formation of hammerhead-like structures with the three stems, or the formation of any two stems, could inhibit translation. Thus, the hammerhead-like structures, leading to cleavage or not, could effectively suppress translation, especially when formed around the initiation codon. The G5-to-A and U7-to-G mutations and replacement of the stem-II hairpin tetraloop did not appear to affect the formation of the inhibitory structure(s). The inhibition that was observed when stems I and III were directly connected without a loop or with a stem II hairpin was completely relieved when they were connected with only the loop of stem II (not containing the stem portion).

Subunits of neurosteroid sulfatase from bovine brain

We have purified the neurosteroid sulfatase (NSS) from Triton X-100 solubilized microsomes of bovine brain about 100-fold. The purified enzyme is composed of two catalytic units (MW: 57 kDa) and two regulatory units (MW: 38 kDa), making it an alpha(2)beta(2) heterotetramer, whose apparent molecular weight was 180 kDa by gel filtration in the presence of Triton X-100.

Origins of the first HLA specificities

Following the discovery of the first histocompatibility antigen "MAC" in 1958, numerous independent laboratories began identifying HLA specificities with allo-antibodies. During the span of about a decade, 1958-1970, virtually all of the common HLA-A and HLA-B antigens were identified by various names and presented at the International Histocompatibility Workshops by means of different serological methods. Because many of the independently discovered specificities were found to be reactive to similar determinants on lymphocytes, it became necessary to classify the antigens by means of a standard method. The micro lymphocytotoxicity test was chosen to be the basis for future antigen testing, thereby allowing the various laboratories to confidently exchange sera. At the 1968 WHO Nomenclature meeting, the naming of the first antigen ultimately gave rise to the designation "HLA" in the human MHC Class I antigen system. This paper looks back upon the origins of the early serologically identified HLA specificities and their respective founders.

Displaced intra-articular calcaneal fracture treated surgically with limited posterior incision

The incidence of calcaneal fracture has been slowly increasing; however, the ideal treatment for displaced intra-articular fracture is not available yet, even though the fracture brings frequent complication and disability. Between April 1991 and March 1998, we treated 103 displaced intra-articular calcaneal fractures of 92 patients surgically with limited posterior incision, modified Gallie approach. There were thirty-seven tongue-type fractures, fifteen tongue-type fractures with moderate comminution, nineteen joint-depression fractures, twenty-nine joint-depression fractures with moderate comminution, and three extensively comminuted fractures. The fracture fragments were fixed mainly with partly threaded small cancellous screws or Steinmann pins without any bone graft. Ankle and subtalar motion was permitted immediately if fixation were stable enough. Otherwise, a short period of cast immobilization was utilized. With a mean follow-up of 28 months (range, 12 to 66 months), eighty six percent of feet had no pain or only occasional pain not requiring medication. Using American Orthopedic Foot and Ankle Society hindfoot score system for assessment, ninety percent of feet rated as good to excellent. We used "Circle draw test" for evaluation of subtalar motion during follow-up visitation and found eight-seven percent of feet showed good to excellent correlation with the functional recovery. We recommend a limited posterior incision for reduction and internal fixation of displaced intra-articular calcaneal fractures. For displaced intra-articular fractures with three or four large fragments without further comminution and without a displaced fracture of the calcaneal cuboid joint, this method is particularly useful. We also recommend a Circle draw test for evaluation of subtalar joint motion as well as an indicator of functional recovery after displaced calcaneal fractures.

A TGF-beta-inducible cell adhesion molecule, betaig-h3, is downregulated in melorheostosis and involved in osteogenesis

Melorheostosis is a rare bone disease characterized by linear hyperostosis and associated soft tissue abnormalities. The skin overlying the involved bone lesion is often tense, shiny, erythematous, and scleodermatous. In order to look for genes differentially expressed between the normal and involved skin, we cultured skin fibroblasts from the skin lesions of several afflicted patients, and identified differentially expressed genes by reverse dot-blot hybridization. We found that the genes human TGF-beta-induced gene product (betaig-h3), osteoblast-specific factor 2, osteonectin, fibronectin, and type I collagen were all downregulated in the affected skin fibroblasts, with betaig-h3 the most significantly affected. The expression of betaig-h3 was induced by TGF-beta in both affected and normal fibroblasts. In an effort to determine the mechanism of bone and skin abnormalities in melorheostosis, we made recombinant betaig-h3. Both immobilized and soluble recombinant betaig-h3 proteins with or without an RGD motif inhibited bone nodule formation of osteoblasts in vitro. Taken together, our results suggest that altered expression of several adhesion proteins may contribute to the development of hyperostosis and concomitant soft tissue abnormalities of melorheostosis, with betaig-h3 in particular playing an important role in osteogenesis.