Cost-effectiveness of FDA variance for blood collection from individuals with hereditary hemochromatosis at a 398-bed hospital-based donor center.

Hereditary hemochromatosis (HH) is treated by therapeutic phlebotomy to reduce excess body iron. This 398-bed, hospital-based donor center wanted to determine whether there was a financial advantage to requesting FDA approval to allow transfusion of blood components from eligible individuals with HH. Donor center records from 2008 were reviewed to identify all therapeutic phlebotomy patients with a diagnosis of HH. HH patients were contacted and asked to complete the AABB Uniform Donor History Questionnaire (UDHQ) to determine their eligibility as potential allogeneic blood donors. Financial ramifications attributable to loss of revenue from the therapeutic phlebotomies($100/collection) were compared with the potential gain in revenue from collecting units for transfusion ($429/collection) in a 12-month period. Nineteen HH patients were identified and screened for allogeneic eligibility. Seventeen patients (89%) met the eligibility criteria for allogeneic donors, and two patients (11%) did not. Retrospective review of donor records indicated that a total of 60 units were collected from these HH patients from January 2008 through December 2008. Fifty-five of the 60 units collected (92%) were eligible for allogeneic use, potentially generating gross revenue of $23,595. After deducting expenses for infectious disease testing and loss of revenue for the nonqualified therapeutic phlebotomies, the net revenue from the collection of 55 RBC units that could have potentially been used for allogeneic transfusion was $20,345. In contrast, the current revenue generated by the collection of 60 therapeutic phlebotomies was only $6,000. In 2008, using eligible HH individuals as allogeneic blood donors would have resulted in an increase in revenue of $14,345 for our blood center.This study demonstrates that even at a medium-size, hospital-based donor center, obtaining a variance from the FDA to establish an HH blood donor program is a cost-effective endeavor, which does not compromise donor or patient safety.

Selective provision of asthma self-management tools to families.

OBJECTIVE: Providing asthma education in a primary care setting can be challenging because of time and resource constraints. The purpose of this work was to determine factors associated with the provision of different asthma self-management tools. METHODS: We conducted a cross-sectional survey with 896 parents of children with asthma (age 2-12 years). We collected information regarding demographics and asthma care, including parent receipt of an asthma action plan, a symptom diary, and asthma information materials; whether an asthma management plan was sent to the child's school; and whether the physician reviewed written instructions on use of a metered-dose inhaler. We used multivariate logistic regression methods to determine factors associated with receipt of different asthma self-management tools controlling for demographic factors. RESULTS: For families where parents only completed high school, there was greater likelihood of receipt of an asthma action plan and physician review of written instructions about how to use an inhaler. For families with a household income less than twice the poverty line, there was greater likelihood of receipt of an asthma action plan, the physician sending a letter to the child's school regarding the child's asthma, and receipt of an asthma symptom diary. CONCLUSIONS: In our sample, primary care pediatricians do not routinely provide asthma education in accordance with National Heart, Lung, and Blood Institute asthma guidelines and "triage" which families receive additional asthma education. We believe that the use of targeted asthma education is a symptom of the limited time and competing demands during a typical visit. As a result, those involved in quality improvement need to help physicians become more efficient and effective at providing asthma education within such time constraints or develop alternative systems of providing asthma education.

Predictors of perceived effort in the shoulder during load transfer tasks.

The mechanism of muscular effort perception in the shoulder was examined in this experiment. Two shoulder biomechanical models and experimental muscle activity data were used to assess physical exposure for a series of reaching tasks. Effort perception was quantitatively correlated to these measures of physical loading, both at the resultant torque (r(2) = 0.50) and muscle activity model-based muscle force predictions (MFPs): r(2) = 0.42, electromyography (EMG): r(2) = 0.26) levels. Muscle data did not explain variation in effort perception more fully than torque data. The inclusion of subject and task variables improved the ability of each model to explain variability in effort perception (torque: r(2) = 0.74; MFP: r(2) = 0.67, EMG: r(2) = 0.64). These results suggest that effort perception may not be fully explained by only an image of the motor command, but is rather a complex integrative quantity that is affected by other factors, such as posture and task goals, which may be dependent on sensory feedback.

Center of pressure excursion capability in performance of seated lateral-reaching tasks.

BACKGROUND: Seated center of pressure excursion capability can be used for patient evaluation in a clinical setting and in universal design. A quantification of excursion capability across age and anthropometry has not been previously reported, although some research suggests that the ischial tuberosities are the support structure limiting the excursion. METHODS: Thirty-eight neurologically healthy adults ranging in age from 21 to 74 years and including 12 obese persons performed a series of 6 lateral-reaching tasks. Participants sat on a platform such that their feet did not touch the ground, leaving their legs free to provide counterbalancing support. Data recorded from a force plate under the platform allowed calculation of the center of pressure throughout the trial and the maximum excursion for each condition was recorded. FINDINGS: The average excursion capability for the healthy, experimental population was 148 mm or 37% of seated hip breadth. Taller participants had larger maximum excursions, on average, than shorter participants, and older participants had smaller excursions than younger participants. INTERPRETATION: The greater trochanter of the femur-rather than the ischial tuberosities-appears to be the primary support structure limiting center of pressure excursion in lateral, balance-limited reaches without contralateral support. These measures and concepts can be used for design, accommodation, and clinically for patient assessment.

Improving digital human modelling for proactive ergonomics in design.

This paper presents the need to improve existing digital human models (DHMs) so they are better able to serve as effective ergonomics analysis and design tools. Existing DHMs are meant to be used by a designer early in a product development process when attempting to improve the physical design of vehicle interiors and manufacturing workplaces. The emphasis in this paper is placed on developing future DHMs that include valid posture and motion prediction models for various populations. It is argued that existing posture and motion prediction models now used in DHMs must be changed to become based on real motion data to assure validity for complex dynamic task simulations. It is further speculated that if valid human posture and motion prediction models are developed and used, these can be combined with psychophysical and biomechanical models to provide a much greater understanding of dynamic human performance and population specific limitations and that these new DHM models will ultimately provide a powerful ergonomics design tool.

Sialylation of group B streptococcal capsular polysaccharide is mediated by cpsK and is required for optimal capsule polymerization and expression.

Several bacterial pathogens have evolved the means to escape immune detection by mimicking host cell surface carbohydrates that are crucial for self/non-self recognition. Sialic acid, a terminal residue on these carbohydrates, inhibits activation of the alternate pathway of complement by recruiting the immune modulating molecule factors H, I, and iC3b. Sialylation of capsular polysaccharide (CPS) is important for virulence of group B streptococci (GBS), a significant human pathogen. We previously reported that cpsK, a gene within the cps locus of type III GBS, could complement a sialyltransferase deficient lst mutant of Haemophilus ducreyi, implicating its role in sialylation of the GBS capsule. To explore the function of cpsK in GBS capsule production, we created a mutant in cpsK. Immunoblot analysis and enzyme-linked immunosorbent assay using anti-type III CPS antisera demonstrated that the mutant CPS did not contain sialic acid. This was confirmed by high-performance liquid chromatography after mild acid hydrolysis of the CPS. Although increased CPS chain length was seen for this strain, CPS production was <20% of the parental isolate. An episomal cpsK copy restored synthesis of sialo-CPS to wild-type levels. These data support our hypothesis that cpsK encodes the GBS CPS sialyltransferase and provide further evidence that lack of CPS oligosaccharide sialylation reduces the amount of CPS expressed on the cell surface. These observations also imply that one or more of the components involved in synthesis or transport of oligosaccharide repeating units requires a sialo-oligosaccharide for complete activity.

Differences in innate immunologic response to group B streptococcus between colonized and noncolonized women.

OBJECTIVE: To evaluate the functional capacity of granulocytes and monocytes from pregnant and nonpregnant women in relation to group B streptococcus (GBS) colonization status. METHODS: Engulfment of fluorescent GBS by peripheral blood phagocytes from GBS-colonized and noncolonized women was measured by flow cytometry. Intracellular superoxiode generated in response to GBS challenge to monocytes and granulocytes enriched from peripheral blood of these women was also measured by flow cytometry, and extracellular superoxide was determined by colorimetric assay. RESULTS: Monocytes and granulocytes from pregnant, GBS-colonized women engulfed significantly greater numbers of GBS than phagocytes from pregnant, noncolonized women. No difference in intracellular superoxide production was detected between any of the groups of women; however, monocytes from pregnant, colonized women released significantly more superoxide into the extracellular milieu than did granulocytes from the same women. No differences in extracellular release of superoxide were observed among noncolonized women whether they were pregnant or not. CONCLUSIONS: Monocytes from pregnant, colonized women engulf more GBS and release more of the superoxide into the extracellular environment, where it is unlikely to be an effective defense mechanism against intracellular bacteria. This suggests that components of the innate immune system that should serve in a protective role may function suboptimally, thereby contributing to the colonization process by GBS.

A three-dimensional dynamic posture prediction model for simulating in-vehicle seated reaching movements: development and validation.

A three-dimensional dynamic posture prediction model for simulating in-vehicle seated reaching movements is presented. The model employs a four-segment 7-degrees-of-freedom linkage structure to represent the torso, clavicle and right upper extremity. It relies on an optimization-based differential inverse kinematics approach to estimate a set of four weighting parameters that quantify a time-constant, inter-segment motion apportionment strategy. In the development phase, 100 seated reaching movements performed by 10 subjects towards five typical in-vehicle targets were modelled, resulting in 100 sets of weighting parameters. Statistical analysis was then conducted to relate these parameters to target and individual attributes. In the validation phase, the generalized model, with parameter values statistically synthesized, was applied to novel data sets containing 700 different reaching movements (towards different targets and/or by different subjects). The results demonstrated the model's ability to generate close representations in prediction: the overall mean time-averaged error in joint angle was 5.2 degrees, and the median was 4.7 degrees, excluding reaches towards two extreme targets (for which modelling errors were excessive). The model's general success in prediction and its unique characteristics led to implications with regard to the performance and underlying control strategies of human reaching movements.

Shoulder disorders and postural stress in automobile assembly work.

OBJECTIVES: A case-referent study was conducted in an automobile assembly plant to evaluate the risk of shoulder disorders associated with nonneutral postures. METHODS: The cases were workers who reported shoulder pain to the plant clinic during a 10-month period and met symptom criteria (pain frequency or duration in the past year) in an interview; more than one-half also had positive findings in a physical examination. The referents were randomly selected workers who were free of shoulder disorders according to the clinic records, the interview, and the physical examination. For each of the 79 cases and 124 referents, 1 job was analyzed for postural and biomechanical demands by an analyst blinded to the case-referent status. RESULTS: Forty-one percent of the subjects flexed or abducted the right arm "severely" (above 90 degrees) during the job cycle, and 35% did so with the left arm. The peak torques at the shoulder were rather low. Shoulder disorders were associated with severe flexion or abduction of the left [odds ratio (OR) 3.2, 95% confidence interval (95% CI) 1.5-6.5] and the right (OR 2.3, 95% CI 1.2-4.8) shoulder. The risk increased as the proportion of the work cycle exposed increased. The relationships were similar for the cases with and without physical findings. Use of hand-held tools increased the risk and also modified the association with postural stress, although the joint exposure distributions limited full analysis of this finding. CONCLUSIONS: The findings support the conclusion that severe shoulder flexion or abduction, especially for 10% or more of the work cycle, is predictive of chronic or recurrent shoulder disorders.

NeuD plays a role in the synthesis of sialic acid in Escherichia coli K1.

The polysialic acid capsule of Escherichia coli K1 is an essential virulence determinant. The kps gene cluster, which encodes the proteins necessary for polymer synthesis and transport, is divided into three functional regions. In this report, we present evidence that the neuD gene from region 2 is involved in sialic acid synthesis. A non-polar chromosomal deletion in neuD was constructed. The defect was complemented by neuD in trans or by the addition of exogenous sialic acid. A NeuD homologue, Neu(III)D, from serotype III Streptococcus agalactiae (GBS) also restored capsule expression to the neuD deletion strain. These data confirm the role of neuD in E. coli sialic acid capsule synthesis and demonstrate that the neu(III)D homologue from GBS shares a similar enzymatic function.

The serotype of type Ia and III group B streptococci is determined by the polymerase gene within the polycistronic capsule operon.

Streptococcus agalactiae is a primary cause of neonatal morbidity and mortality. Essential to the virulence of this pathogen is the production of a type-specific capsular polysaccharide (CPS) that enables the bacteria to evade host immune defenses. The identification, cloning, sequencing, and functional characterization of seven genes involved in type III capsule production have been previously reported. Here, we describe the cloning and sequencing of nine additional adjacent genes, cps(III)FGHIJKL, neu(III)B, and neu(III)C. Sequence comparisons suggested that these genes are involved in sialic acid synthesis, pentasaccharide repeating unit formation, and oligosaccharide transport and polymerization. The type III CPS (cpsIII) locus was comprised of 16 genes within 15.5 kb of contiguous chromosomal DNA. Primer extension analysis and investigation of mRNA from mutants with polar insertions in their cpsIII loci supported the hypothesis that the operon is transcribed as a single polycistronic message. The translated cpsIII sequences were compared to those of the S. agalactiae cpsIa locus, and the primary difference between the operons was found to reside in cps(III)H, the putative CPS polymerase gene. Expression of cps(III)H in a type Ia strain resulted in suppression of CPS Ia synthesis and in production of a CPS which reacted with type III-specific polyclonal antibody. Likewise, expression of the putative type Ia polymerase gene in a type III strain reduced synthesis of type III CPS with production of a type Ia immunoreactive capsule. Based on the similar structures of the oligosaccharide repeating units of the type Ia and III capsules, our observations demonstrated that cps(Ia)H and cps(III)H encoded the type Ia and III CPS polymerases, respectively. Additionally, these findings suggested that a single gene can confer serotype specificity in organisms that produce complex polysaccharides.

Motion times, hand forces, and trunk kinematics when using material handling manipulators in short-distance transfers of moderate mass objects.

The risk of musculoskeletal injury associated with manual materials handling tasks has led in part to the use of material handling manipulators, yet there is limited empirical data to facilitate selection, design, and evaluation of these devices. A laboratory study of two types of mechanical manipulators (articulated arm and overhead hoist) was conducted of short-distance transfers of moderate loads, and the influence of various task parameters and transfer method on motion times, peak hand forces, and torso kinematics was obtained. Use of manipulators increased elemental motion times for symmetric sagittal plane transfers by 36-63%, and asymmetric transfers (in the frontal plane) by 62-115%, compared to similar transfers performed manually. Peak hand forces were significantly lower with both manipulators (40-50%), and approximately 10% higher for asymmetric versus symmetric transfers. Overall torso kinematics were grossly similar with and without a manipulator. These results suggest that for self-paced job tasks, moderate mass objects will be transferred slower over short distances and with lower levels of external (hand) forces when using mechanical aids. These simple effects, however, were influenced by object mass and transfer height.

Computer-aided ergonomics: a case study of incorporating ergonomics analyses into workplace design.

One of the primary goals of computer-aided ergonomics is to develop software tools that allow ergonomics information to be accessed at the earliest stages of design. This case study discusses a PC-based software program that allows a designer to quantify a worker's biomechanical risk for injury based on a proposed workplace design. The program couples an established software tool for biomechanical analysis, the Three-Dimensional Static Strength Prediction Program (3DSSPP), with a widely used computer-aided design software package, AutoCAD. The use of this "3DSSPP/AutoCAD interface" in the proactive analysis of an automotive assembly task is described and the results compared with an independent assessment using observations of workers performing the same task. Both studies yield similar conclusions, suggesting that proactive use of software such as the 3DSSPP/AutoCAD interface may be a valid tool in evaluating proposed workplace designs. In this context, issues in the analysis of workplace designs regarding the use of supporting ergonomic tools, assumptions, and posture selection are discussed.

Back lift versus leg lift: an index and visualization of dynamic lifting strategies.

The description of a lifting strategy is typically provided in qualitative terms. A quantitative static descriptor or index differentiates the starting postures but not the primary moving segments. This technical note proposes an index that quantitatively characterizes different dynamic postural strategies employed during sagittal plane lifting. Dynamic lifting strategies are modeled in the velocity domain as different schemes of partitioning postural changes between the torso and leg segments. The index consists of two parameters, assigned to two leg segments, quantifying their contributions relative to the torso. Given a measured lifting movement, its index parameters values, ranging from 0.1 to 10, are estimated through an enumeration search process with the objective of minimizing the fitting error. The use of this index is illustrated by applying it to 24 lifting movements performed by six subjects assuming either a back-lift or a leg-lift strategy. Results indicate that a lifting strategy, in terms of whether the leg or the back is generally the prime mover, can be differentiated and visualized using this simple two-parameter index. In addition, indistinct intermediate strategies are also discerned, as the involvement of each segment in a lifting movement is quantified. The index is however limited in that it does not accommodate arm motion contributions to a lift nor possible time-dependent strategic changes during a lift. Potential future applications include time-efficient movement prediction and simulation for computerized biomechanical or ergonomic analysis.

Stature, age, and gender effects on reach motion postures.

The rapid adoption of software to simulate human reach motions in the design of vehicle interiors and manufacturing and office workstations has required a sophisticated understanding of human motions. This paper describes how more than 3,000 right-arm reaching motions of a diverse group of participants were captured and statistically modeled. The results demonstrate that stature and age have a larger effect than does gender on reach motion postures for motions chosen by the participants while reaching to targets placed throughout a typical automobile interior. We propose that these methods, models, and results can assist the further development of human motion simulation software for ergonomic purposes, such as for the design or evaluation of vehicle interiors or industrial workplaces, to ensure that various population groups are physically accommodated.

Effects of pacing when using material handling manipulators.

Common manipulator-assisted materials handling tasks were performed in a laboratory simulation at self-selected and faster (paced) speeds. The effects of pacing on peak hand forces, torso kinematics, spine moments and forces, and muscle antagonism were determined, along with any influences of several task variables on these effects. The faster trials were performed 20% more rapidly than the self-paced trials. It was found that (a) achieving this level of performance required approximately 10% higher hand forces and 5%-10% higher torso moments, (b) consistent torso postures and motions were used for both speed conditions, and (c) the faster trials resulted in approximately 10% higher spine forces and approximately 15% higher levels of lumbar muscle antagonism. On whole, these results suggest a higher risk of musculoskeletal injury associated with performance of object transfers at faster than self-selected speeds with and without a manipulator. Further analysis provided evidence that the use of manipulators involves higher levels of motor coordination than do manual tasks. Several implications regarding the use of material handling manipulators in paced operations are discussed. Results from this investigation can be used in the design, evaluation, and selection of material handling manipulators.

Rectifying postures reconstructed from joint angles to meet constraints.

Postures are often described and modeled using angles between body segments rather than joint coordinates. Models can be used to predict these angles as a function of anthropometry and postural requirements. Postural representation, however, requires the joint coordinates. The use of conventional forward kinematics to derive joint coordinates from predicted angles may violate task constraints, such as the placement of a hand on a target or a foot on a pedal. Errors arise because the anthropometry or other motion characteristics of a subject, for which the prediction is to be made, may differ from the data from which the prediction model was derived. We describe how to rectify model-predicted postures to exactly satisfy such task constraints. We require that the model used for predicting the angles also produce estimates of the variation in these predictions. We show how to alter the initial angle predictions, with the amount of perturbation at each angle dependent on the accuracy of its estimation, so as to exactly satisfy the joint coordinate constraints. Finally, we show in an empirical example that this correction usually produces better overall predictions of posture than those obtained initially.

Low-back stresses when learning to use a materials handling device.

This study examines the potential effect of short-term practice on low-back stresses during manual lifting and lowering of a 15 kg load, and while using two different types of materials handling devices (MHDs) to lift and lower a 40 kg load. The two MHDs used were an articulated balance arm and a pneumatic hoist. The expectation was that low-back dynamic moments, EMG measured torso muscle antagonism, and EMG predicted L4/L5 disc compression forces would rapidly decrease with practice, and that the manual lift-lower activities would be learned faster than the MHD-assisted exertions. Four naïve male college age subjects performed 40 lift and lower exertions, both manually and with the two MHDs for a total of 24 experiments. Non-linear regressions of the peak and average low-back moments, EMGs and disc compression values revealed only small decreases in the values (from 2 to 14%) over the 40 trials, and it was only statistically significant for five of the 48 regressions. This would seem to indicate that if learning is present in these tasks it is going to be very slow learning, and thus future studies will need to include a much larger number of trials. The effects of MHDs on the learning rates when compared to manual lifting learning rates was not statistically significant. It was shown, however, that MHDs had a particularly beneficial effect on reducing L4/L5 compression forces during load lowering activities despite the MHD load being much heavier than the manual load. It also was found that the level of torso muscle co-contraction increased significantly (2-4 times) when MHD handling was involved compared to manual lifting and lowering.