Impaired hospitalized patient mobility is associated with nurse injuries.

BACKGROUND: Staff injuries adversely affect the health of staff members as well the ability of health care teams to effectively care for patients. Identifying patients who pose an increased risk of injury may allow for the planning of risk mitigation strategies, but few studies have examined patient factors associated with staff injury risk. AIMS: Examine the relationship between staff injury and patient mobility, which has been linked to other key hospital outcomes. METHODS: Linking occupational health and electronic medical record data, we examined documented patient mobility levels, based on the Activity Measure for Post-Acute Care (AM-PAC) and the Johns Hopkins Highest Level of Mobility (JH-HLM) Scale, on the day prior to injury. In addition, we created a matched cohort of control patients not associated with staff injury to examine the influence of patient mobility on the odds of staff injury. RESULTS: We identified 199 staff injuries associated with 181 patients with 1063 matched controls. Patients had median scores of 11 and 3 on the AM-PAC and JH-HLM, respectively, indicating moderate-severe mobility impairments. In addition, scores in the lowest AM-PAC tertile (6-15) and lowest JH-HLM tertile (1-4) were associated with a 4.46-fold and 2.90-fold increase in the odds of nurse injury, respectively. CONCLUSIONS: These results indicate that moderate-severe mobility impairments are associated with increased risk of nurse injury. Hospitals and clinical care teams should consider documenting mobility routinely and utilizing these values to identify patients who pose an increased risk of nurse injury.

Hypersingular meshless method using double-layer potentials for three-dimensional exterior acoustic problems.

Three-dimensional exterior acoustic problems with irregular domains are solved using a hypersingular meshless method. In particular, the method of fundamental solutions (MFS) is used to formulate and analyze such acoustic problems. It is well known that source points for MFS cannot be located on the real boundary due to the singularity of the kernel functions. Thus, the diagonal terms of the influence matrices are unobtainable when source points are located on the boundary. An efficient approach is proposed to overcome such difficulties, when the MFS is used for three-dimensional exterior acoustic problems. This work is an extension of previous research on two-dimensional problems. The solution of the problem is expressed in terms of a double-layer potential representation on the physical boundary. Three examples are presented in which the proposed method is compared to the MFS and boundary element method. Good numerical performance is demonstrated by the proposed hypersingular meshless method.

Copepods' Response to Burgers' Vortex: Deconstructing Interactions of Copepods with Turbulence.

This study examined the behavioral response of two marine copepods, Acartia tonsa and Temora longicornis, to a Burgers' vortex intended to mimic the characteristics of a turbulent vortex that a copepod is likely to encounter in the coastal or near-surface zone. Behavioral assays of copepods were conducted for two vortices that correspond to turbulent conditions with mean dissipation rates of turbulence of 0.009 and 0.096 cm(2) s(-3) (denoted turbulence level 2 and level 3, respectively). In particular, the Burgers' vortex parameters (i.e., circulation and rate of axial strain rate) were specified to match a vortex corresponding to the median rate of dissipation due to viscosity for each target level of turbulence. Three-dimensional trajectories were quantified for analysis of swimming kinematics and response to hydrodynamic cues. Acartia tonsa did not significantly respond to the vortex corresponding to turbulence level 2. In contrast, A. tonsa significantly altered their swimming behavior in the turbulence-level-3 vortex, including increased relative speed of swimming, angle of alignment of the trajectory with the axis of the vortex, ratio of net-to-gross displacement, and acceleration during escape, along with decreased turn frequency (relative to stagnant control conditions). Further, the location of A. tonsa escapes was preferentially in the core of the stronger vortex, indicating that the hydrodynamic cue triggering the distinctive escape behavior was vorticity. In contrast, T. longicornis did not reveal a behavioral response to either the turbulence level 2 or the level 3 vortex.

Matrix stimulates the proliferation of human corneal endothelial cells in culture.

PURPOSE: Extracellular matrices were tested for their ability to support the adhesion and proliferation of human corneal endothelial cells. METHODS: Human corneal endothelial cells were plated onto tissue culture dishes coated with purified fibronectin or a matrix elaborated by cultured bovine corneal endothelial cells. The presence of human cells in the cultures was confirmed by karyotyping. Cell size at increasing passage number was analyzed, and cellular response to growth factors was assessed using a 96-well microtiter plate assay. RESULTS: When tissue culture dishes were coated with fibronectin, the cells attached to the dish but grew slowly. Human corneal endothelial cells plated onto the matrices elaborated by bovine corneal endothelial cells attached to the culture dish and grew to fill the flask. At confluence, the cells had a hexagonal morphology similar to that seen in vivo. Karyotype analysis showed that the cells were of human and not bovine origin. The time required for senescence in culture was dependent on the age of the donor cornea. The bovine matrices enhanced the proliferative response of human corneal endothelial cell cultures to endothelial cell growth supplement and keratinocyte growth factor. Epidermal growth factor and hepatocyte growth factor stimulated human cell proliferation in a dose-dependent fashion, regardless of the substratum on which the cells were plated. CONCLUSIONS: The use of substratum elaborated by bovine corneal endothelial cells has proved useful in the preparation of human endothelial cell cultures from juvenile and adult donors. The method has been used to establish cultures from more than 50 donors from age 1 day to 76 years.

Short-term potentiation of carotid chemoreflex: an NMDAR-dependent neural integrator.

Repetitive stimulation of the carotid sinus nerve (CSN) elicits a short-term potentiation (STP) of the reflex response in respiratory motor output in mammals. The input-output transformation approximates a leaky integrator with a time constant of several seconds. Here, we showed that STP induced by CSN stimulation in rats was manifested in the reflex response in the amplitude of rhythmic phrenic nerve activity as well as its duration. Moreover, pharmacological blockade of NMDA receptors (NMDAR) resulted in marked increases in the time constants of the equivalent neural integrator in both the STP induction phase (by 10- to 20-fold) and recovery phase (by 1- to 5-fold). Thus, NMDAR serves as a molecular switch that facilitates the integrative processing of CSN inputs by STP.

High-pass filtering of carotid-vagal influences on expiration in rat: role of N-methyl-D-aspartate receptors.

Repetitive electrical stimulation of the carotid sinus nerve or vagus nerve in rats elicited abrupt reflex shortening or prolongation, respectively, of the inter-burst interval of phrenic nerve activity followed by exponential decay from the initial response. Removal of the stimuli resulted in transient post-stimulus rebound excitation or inhibition that mirrored the corresponding stimulus-evoked responses. The biphasic responses to these complementary inputs approximate the on- and off-transients of full-wave differentiators or high-pass filters. Blockade of N-methyl-D-aspartate (NMDA) receptors abolished the post-stimulus rebounds and transformed both signal pathways into integrators or low-pass filters, thus switching off part or all of the high-pass filters. We suggest that such NMDA receptor-dependent high-pass filtering effects may serve to increase the dynamic range and response speed of sensory neurotransmission to the brain, thereby enhancing closed-loop stability of sensorimotor reflex.

Practical immunochemical method for determination of 3,5, 6-trichloro-2-pyridinol in human urine: applications and considerations for exposure assessment.

An analytical method is described for the quantitative determination of 3,5,6-trichloro-2-pyridinol (3,5,6-TCP) in human urine. This is the primary analyte found in urine as a result of exposure to chlorpyrifos, chlorpyrifos-methyl, triclopyr, or 3,5,6-TCP. Conjugates of 3,5,6-TCP are released from urine by acid hydrolysis. The free 3,5,6-TCP is purified using C(18) solid-phase extraction, eluting the analyte with 1-chlorobutane. An aliquot of 1-chlorobutane is placed in a vial containing Trichloropyridinol Sample Diluent and evaporated, leaving the 3,5,6-TCP in the aqueous sample diluent. The samples are assayed using the Trichloropyridinol RaPID Assay immunoassay test kit. Final results are calculated using a standard curve constructed by linear regression after a ln/Logit data transformation is performed of the concentration and the absorbance readings, respectively. The calculated lower limit of quantitation for 3,5,6-TCP in fortified control urine samples is 2. 96 ng/mL (2.96 ppb). Residues of 3,5,6-TCP determined using both immunochemical and gas chromatography with mass spectrometric detection correlate well.

Determination of spinosad and its metabolites in food and environmental matrices. 3. Immunoassay methods.

Spinosad is an insect control agent that is derived from a naturally occurring soil bacterium and is effective on several classes of insects, especially Lepidopteran larvae. Spinosad is registered in many countries for use on a variety of crops, including cotton, corn, soybeans, fruits, and vegetables. Residue methods utilizing a magnetic particle-based immunoassay (IA) test kit have been developed and validated for determining spinosad in environmental and food matrices. These methods involve an extraction of the residues from the matrices with appropriate solvents. For some matrices, the sample extracts can be diluted and measured directly by IA without any cleanup. For other matrices, sample extracts are purified using liquid-liquid partitioning and/or solid phase extraction prior to measurement by IA. The methods determine the total residue of spinosad, which includes the active ingredients (spinosyns A and D) and several minor metabolites, including spinosyn B, spinosyn K, and N-demethylspinosyn D. The methods have validated limits of quantitation of 0.0001 microgram/mL in water, 0.05 microgram/g in sediment, and 0.010 microgram/g in crops, crop processed commodities, and animal tissues. This paper briefly summarizes the residue methodology and method validation data for spinosad in 34 food, feed, and environmental matrices.

Fine structure of the retinal epithelial regions of the red kangaroo (Macropus rufus).

The fine structure of the retinal epithelium, Bruch's membrane, and choriocapillaris has been studied by electron microscopy in the red kangaroo (Macropus rufus). The retinal epithelium consists of a single layer of pigmented, squamous cells. The epithelial cells are joined laterally by tight junctions and throughout the retina, display numerous basal infoldings and apical processes that enclose photoreceptor outer segments. The retinal epithelial cells are rich in smooth endoplasmic reticulum and mitochondria. Polysomes are a constant feature and the cells contain few profiles of rough endoplasmic reticulum. Membrane bound phagosomes of outer segment discs are frequently seen. All cells examined contain spherical to oval shaped pigment granules. We find no evidence of a tapetum either in the retinal epithelium or the choroid. Wandering phagocytes are occasionally observed at the photoreceptor-retinal epithelial junction. The presence of these cells has been reported in lower vertebrates but less frequently in mammals. Bruch's membrane displays the typical pentalaminate structure described for most vertebrates. The endothelium of the choriocapillaris is very thin and is highly fenestrated facing Bruch's membrane with a few fenestrations also present on the side bordering the choroid.

Seasonality of Chlamydia trachomatis genital infections in university women.

Previous studies have shown seasonal fluctuations in the incidence of most sexually transmitted diseases, with a peak in the third quarter, but none have specifically evaluated Chlamydia trachomatis genital infections. From 1989 to 1991, 8,234 women presenting to the student health centers of Florida's two largest universities for routine gynecologic care and diagnosis of sexually transmitted diseases were tested for Chlamydia trachomatis genital infections. The bimonthly variation in incidence was statistically significant, with a significant peak in the months of August and September of 10.70%, compared with the yearly average of 8.74%. Because the pattern of incidence of chlamydia in university women is seasonal, those concerned with healthcare should increase their efforts during the third quarter to identify infected individuals and to provide preventive programs.

Comparison of the cytology brush with the Dacron swab for detecting Chlamydia trachomatis by enzyme immunoassay in female university students.

Previous studies comparing the cytology brush (Cytobrush) with swabs for the detection of Chlamydia trachomatis from the uterine cervix have yielded divided results. The authors carried out a retrospective analysis at the University of South Florida Student Health Service to evaluate the effect of a change in specimen collection technique on C trachomatis prevalence estimates in female university students. Samples were collected from 1,003 women in 1989, using a small Dacron swab, and 1,229 women in 1990, using a brush; the samples were tested by means of the Pathfinder Enzyme Immunoassay (EIA) detection kit. Positive test results were 5.88% for 1989 and 11.66% for 1990. Actual C trachomatis prevalence for 1989 and 1990 was stable, as determined by three control groups. The results suggest that the cytology brush is more effective than the Dacron swab for the detection of C trachomatis in the uterine cervix when it is used with the Pathfinder EIA test kit.

A Hebbian feedback covariance learning paradigm for self-tuning optimal control.

We propose a novel adaptive optimal control paradigm inspired by Hebbian covariance synaptic adaptation, a preeminent model of learning and memory as well as other malleable functions in the brain. The adaptation is driven by the spontaneous fluctuations in the system input and output, the covariance of which provides useful information about the changes in the system behavior. The control structure represents a novel form of associative reinforcement learning in which the reinforcement signal is implicitly given by the covariance of the input-output (I/O) signals. Theoretical foundations for the paradigm are derived using Lyapunov theory and are verified by means of computer simulations. The learning algorithm is applicable to a general class of nonlinear adaptive control problems. This on-line direct adaptive control method benefits from a computationally straightforward design, proof of convergence, no need for complete system identification, robustness to noise and uncertainties, and the ability to optimize a general performance criterion in terms of system states and control signals. These attractive properties of Hebbian feedback covariance learning control lend themselves to future investigations into the computational functions of synaptic plasticity in biological neurons.

Generalized neuromuscular hypoplasia, reduced smooth muscle myosin and altered gut motility in the klotho model of premature aging.

BACKGROUND: Gastrointestinal symptoms, particularly constipation, increase with aging, but their underlying mechanisms are poorly understood due to lack of experimental models. Previously we established the progeric klotho mouse as a model of aging-associated anorexia and gastric dysmotility. We also detected reduced fecal output in these animals; therefore, the aim of this study was to investigate in vivo function and cellular make-up of the small intestinal and colonic neuromuscular apparatus. METHODS: Klotho expression was studied by RT-PCR and immunohistochemistry. Motility was assessed by dye transit and bead expulsion. Smooth muscle and neuron-specific gene expression was studied by Western immunoblotting. Interstitial cells of Cajal (ICC) and precursors were analyzed by flow cytometry, confocal microscopy, and three-dimensional reconstruction. HuC/D(+) myenteric neurons were enumerated by fluorescent microscopy. KEY RESULTS: Klotho protein was detected in neurons, smooth muscle cells, and some ICC classes. Small intestinal transit was slower but whole-gut transit of klotho mice was accelerated due to faster colonic transit and shorter intestinal lengths, apparent only after weaning. Fecal water content remained normal despite reduced output. Smooth muscle myosin expression was reduced. ICC, ICC precursors, as well as nitrergic and cholinergic neurons maintained their normal proportions in the shorter intestines. CONCLUSIONS & INFERENCES: Progeric klotho mice express less contractile proteins and develop generalized intestinal neuromuscular hypoplasia mainly arising from stunted postweaning growth. As reduced fecal output in these mice occurs in the presence of accelerated colonic and whole-gut transit, it likely reflects reduced food intake rather than intestinal dysmotility.

Singular meshless method using double layer potentials for exterior acoustics.

Time-harmonic exterior acoustic problems are solved by using a singular meshless method in this paper. It is well known that the source points cannot be located on the real boundary, when the method of fundamental solutions (MFS) is used due to the singularity of the adopted kernel functions. Hence, if the source points are right on the boundary the diagonal terms of the influence matrices cannot be derived. Herein we present an approach to obtain the diagonal terms of the influence matrices of the MFS for the numerical treatment of exterior acoustics. By using the regularization technique to regularize the singularity and hypersingularity of the proposed kernel functions, the source points can be located on the real boundary and therefore the diagonal terms of influence matrices are determined. We also maintain the prominent features of the MFS, that it is free from mesh, singularity, and numerical integration. The normal derivative of the fundamental solution of the Helmholtz equation is composed of a two-point function, which is one of the radial basis functions. The solution of the problem is expressed in terms of a double-layer potential representation on the physical boundary based on the potential theory. The solutions of three selected examples are used to compare with the results of the exact solution, conventional MFS, boundary element method, and Dirichlet-to-Neumann finite element method. Good numerical performance is demonstrated by close agreement with other solutions.

Estradiol- and testosterone-induced alterations in phosphatidylcholine and triglyceride synthesis in hepatic endoplasmic reticulum.

Pathways of phosphatidylcholine and triglyceride biosynthesis were studied in hepatic endoplasmic reticulum from castrated and noncastrated male rats pretreated with estradiol or testosterone. In vitro measurements of hepatic microsomal enzymes which catalyze phosphatidylcholine biosynthesis revealed a significant increase in the specific activity of the enzyme governing phosphatidylcholine biosynthesis by the sequential methylation of phosphatidylethanolamine in the estradiol-treated castrate animals. The specific activity of phosphorylcholine-glyceride transferase was decreased by estradiol treatment in both castrate and noncastrate animals. The specific activity of diglyceride acyltransferase, which catalyzes triglyceride biosynthesis, was decreased by estradiol pretreatment in both castrate and noncastrate animals and was increased by testosterone in the castrate animals. The changes in specific activity of the enzymes governing phosphatidylcholine biosynthesis may account for the previously noted increased in vivo incorporation of methyl groups of l-methionine into hepatic phosphatidylcholine in female and estradiol-treated animals; the data suggest that in female and estradiol-treated rats a greater proportion of hepatic phosphatidylcholine is synthesized by the stepwise methylation of phosphatidylethanolamine. The decrease in diglyceride acyltransferase specific activity seen after estradiol administration may account for the lipotropic-like effect of estradiol.

Retinal pigment epithelial fine structure in the great blue heron (Ardea herodias).

The fine structure of the retinal epithelium (RPE), choriocapillaris and Bruch's membrane (complexus basalis) has been studied by light and electron microscopy in the great blue heron (Ardea herodias). In this species the RPE consists of a single layer of cuboidal cells which display numerous basal (scleral) infoldings and plentiful apical (vitreal) processes which surround photoreceptor outer segments. These epithelial cells are joined laterally by a series of tight junctions located in the mid to basal region. Within the epithelial cells, smooth endoplasmic reticulum is very abundant while rough ER is not. Mitochondria (some of which are ring-shaped) and polysomes are abundant. In light-adaptation the RPE nuclei are large vesicular and basally located while the melanosomes of these cells are almost exclusively located within the apical processes. Myeloid bodies are large and numerous and often show ribosomes on their outer surface. Bruch's membrane (complexus basalis) shows the typical pentalaminate structure noted in the majority of vertebrates except teleosts. The choriocapillary endothelium is very thin facing Bruch's membrane but is only moderately fenestrated. The majority of these fenestrations show a single-layered diaphragm but double-layered diaphragms are also noted.

Effect of bile salts on hepatic phosphatidylcholine synthesis and transport into rat bile.

The effect of transport of micelle-forming and non-micelle-forming conjugated bile salts on phosphatidylcholine synthesis and transport into bile was studied in the ex vivo perfused rat liver. Single additions of sodium taurocholate, a good micelle-forming conjugated bile salt, caused an increase in bile flow associated with increased phosphatidylcholine and taurocholate concentration. The specific activity of phosphatidylcholine with respect to incorporated [1,2-(14)C]choline and [(3)H]methyl of l-[Me-(3)H]methionine was not significantly altered by the increased transport of phosphatidylcholine. The data suggested that bile phosphatidylcholine is synthesized to a great extent, although not exclusively, by phosphorylcholine glyceride transferase. Single additions of the glycine conjugate of dehydrocholate, a poor micelle-forming bile salt, caused an increase in bile flow comparable to that seen with sodium taurocholate administration. However, the concentrations of phosphatidylcholine in bile decreased. Thin-layer and gas-liquid chromatographic analyses of bile secreted before and after glycodehydrocholate administration revealed no significant increase in bile salt secretion other than the administered glycodehydrocholate. Investigations utilizing radiochemically pure [(14)C]glycine dehydrocholate revealed that increased bile flow after [(14)C]-glycine dehydrocholate administration occurs concomitantly with the secretion of 75-95% of the administered [(14)C]glycine dehydrocholate as a single peak into bile. Thus the increased bile flow without increased phosphatidylcholine concentration noted after glycodehydrocholate administration is due to transport of an intact, nonmetabolized, conjugated bile salt with poor micelle-forming properties. The data indicate that the formation of a bile salt-phosphatidylcholine micelle is responsible for phosphatidylcholine transport into bile.