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At least 1,207 records · Page 67Linked to original sources

When back pain becomes disabling: a regional analysis.

Back pain is a common condition and in most cases is not disabling. We have investigated disabling back pain that leads to health care utilization, time lost from work, and high costs. Disabling back pain remains of obscure origin because the focus in studying it has been too narrow. Our indicator of disability is the industrial insurance claim rate for back sprain by county (N = 39) in the State of Washington. After controlling for the size of the labor force and the proportion of workers in occupations that are particularly at risk of back sprain, we determined the effect of 3 socioeconomic factors on the claim rate: the unemployment rate, percentage receiving food stamps, and per capita income. For 2 of the 3 years studied, socioeconomic factors accounted for about one-third of the variance in the claim rate. Even though claimants of industrial insurance are employed, the unemployment rate was significantly related to the claim rate in the 3 years studied. Our interpretation is that disability is a symptom of distress. Where there is a rise in job insecurity and an attendant rise in economic insecurity, there is a greater likelihood that back pain will become disabling.

Back Pain↗

Refinement of the scrap technique of skin grafting.

A technique to obtain a sheet of meshed skin by assembling many small skin grafts is described. The merits of this technique are that a meshed skin graft of desired size and shape is obtained using many small pieces of skin, and moreover, these pieces of skin do not break down when meshed or when applied to the recipient bed, since the graft is reinforced by a plastic film. Graft survivals and epithelialization of the wound are excellent. This technique is especially useful in extensively burned patients with a limited and scattered donor area, and also for patients who require stamp grafts but are not cooperative enough to keep still for prolonged periods after surgery.

Burns↗

Determination of the Lewis blood group substances in stains of forensically relevant body fluids.

Forensic investigations often demand a clear definition of secretor status. Lewis-typing of secretion stains may help to verify non-secretor results and to identify mixtures of secretions from Le (a-b-) persons and secretors (or non-secretors). Furthermore it gives an additional check on secretor status, determined by ABO-grouping. Few problems may arise, when testing prepared saliva or semen stains. Therefore our interest was focussed on the possibility of Lewis-typing in stains appearing in forensic case work such as cigarette tips, stamps and envelope flaps, semen stains and vaginal swabs, nasal secretion, sweat and urine stains. All stains with the exception of sweat and urine were successfully Lewis-typed. In saliva stains Lewis substances could be determined even after 5 years and in semen stains for at least up to 40 days.

Body Fluids↗

Biomechanical properties of the human tibia: fracture behavior and morphology.

Standardized biomechanical dynamic load tests were performed to obtain fundamental information on the fracture behavior and morphology of the human tibia. After preparation, the specimens (n = 32) were loaded to breakage by ventral (one side alternately), dorsal, medial or lateral loading on a servo-hydraulic testing machine (Walter und Bai, Löhningen, Switzerland). Primary and secondary fracture lines and fissures were marked differently on the three surfaces of the tibia specimens. They were then videoscanned and digitized on a flatbed scanner to give two-dimensional fracture-line images. Load limits were 2475 to 12,206 Newton. The study revealed both direct fracture patterns with the fracture lines originating from the opposite site of impact, and indirect fracture patterns originating from the distal third of the specimens. Direct fractures occurred in 46% of the specimens after ventral loading, in 80% after medial or lateral loading, and in 100% after dorsal loading. Ventral, medial or lateral loading frequently produced direct wedge fractures of the Messerer type. Dorsal loading resulted in different direct patterns characterized by transverse fractures with longitudinal fissures at the impact site of the loading stamp. Direct transverse fractures also often showed a wedge-shaped pattern due to additional fissures. These were, however, identifiable only after maceration of the specimens and should receive closer attention in forensic practice.

Adolescent↗

Anemia as an indicator of nutrition in children enrolled in a Head Start program.

A retrospective chart review was conducted on the records of 467 children who were enrolled in the Head Start program in Alachua County, Florida, which is one of four counties in Florida cited among the 150 worst "hunger counties" in the United States by the Harvard University School of Public Health. The children were examined in the 1989-1990 school year by a team of nurse practitioners, and the data were analyzed to determine the incidence and distribution of anemia. Twenty-five percent of the sample was white, and 75% was black. One half of the white children and 20% of the black children attended schools in rural areas. The mean sample hematocrit value was 35.7%. Twenty-one percent of the sample had hematocrit values of less than 34.0%. More black children were anemic in both rural and urban groups. Black males had the highest rate of anemia at 27.3%; white females had the lowest rate of anemia at 9.8%. These data show that anemia is a serious problem among children from low-income families and suggest that government nutrition programs such as food stamps and WIC are not meeting the needs of these children.

Anemia, Hypochromic↗

Knowledge-based temporal abstraction in clinical domains.

We have defined a knowledge-based framework for the creation of abstract, interval-based concepts from time-stamped clinical data, the knowledge-based temporal-abstraction (KBTA) method. The KBTA method decomposes its task into five subtasks; for each subtask we propose a formal solving mechanism. Our framework emphasizes explicit representation of knowledge required for abstraction of time-oriented clinical data, and facilitates its acquisition, maintenance, reuse and sharing. The RESUME system implements the KBTA method. We tested RESUME in several clinical-monitoring domains, including the domain of monitoring patients who have insulin-dependent diabetes. We acquired from a diabetes-therapy expert diabetes-therapy temporal-abstraction knowledge. Two diabetes-therapy experts (including the first one) created temporal abstractions from about 800 points of diabetic-patients' data. RESUME generated about 80% of the abstractions agreed by both experts; about 97% of the generated abstractions were valid. We discuss the advantages and limitations of the current architecture.

Artificial Intelligence↗

Computer system for the acquisition and analysis of vascular contractility. Application to a bioassay of endothelial cell function.

A system for the digital acquisition and subsequent analysis of the tension developed by isolated blood vessels in response to an endothelial cell superfusate is reported. Tension of the isolated rat aortic rings was measured by strain gauge. Strain-gauge output was then amplified, and the analog signal was digitized on a 16-channel A/D board. Lab tech Notebook software was used to display and store the data. The sampling rate was 0.1 Hz, and the data was written concurrently to hard disk and printer. Both disk and printer output were accompanied by a time stamp for subsequent ease of retrieval. The endothelial cell bioassay system allowed measurement of changes in vascular tension after the release of endothelium-dependent relaxing factor, nitric oxide (EDRF-NO) from cultured cells. Cells were cultured on microcarrier beads, formed into columns, and perfused with physiological salt solution. Significant (p < 0.05) relaxant responses occurred after agonist stimulation with bradykinin (10(-8) M; Emax -31.0% +/- 8.2%), acetylcholine (10(-8) M; Emax -33.2% +/- 5.0%), and calcium ionophore A 23187 (10(-6) M; Emax -55.7% +/- 15.4%). These responses were dependent on EDRF-NO, as shown by both the lack of relaxation in the absence of endothelial cells, and that relaxation to A 23187 was overcome by hemoglobin (3 x 10(-6) M). Results were manipulated graphically to allow the superimposition of data and thereby provide a mean and standard error of the mean for the entire time course of each response. Thus, a system was produced where fidelity of data expression was not dependent on measurements made at single points, but on the sampling frequency of the acquisition system.

Animals↗

Empirical Bayes before-after safety studies: lessons learned from two decades of experience and future directions.

The empirical Bayes (EB) methodology has been applied for over 20 years now in conducting statistically defendable before-after studies of the safety effect of treatments applied to roadway sites. The appeal of the methodology is that it corrects for regression to the mean and traffic volume and other changes not due to the measure. There is, therefore, a natural tendency to put a stamp of approval on any study that uses this methodology, and to assume that the results can then be used in specifying crash modification factors for use in developing treatments for hazardous locations, or in designing new roads using tools such as the interactive highway safety design model (IHSDM). At the other extreme are skeptics who suggest that the increased sophistication and data needs of the EB methodology are not worth the effort since alternative, less complex methods can produce equally valid results. The primary objective of this paper is to capitalize on experience gained from two decades of conducting EB studies around the world to illustrate that the EB methodology, if properly undertaken, produces results that could be substantially different and less biased than those from more conventional types of studies. A secondary objective is to emphasize that caution is needed in assessing the validity of studies undertaken with the EB methodology and in using these results for providing crash modification factors. To this end, a number of issues that are critical to the proper conduct and interpretation of EB evaluations are raised and illustrated based on lessons learned from recent experience with these studies. These include: amalgamating the effects on different crash types; the specification of the reference/comparison groups; and accounting for traffic volume changes. Current and future directions, including the improvements offered by a full Bayes approach, are discussed.

Accidents, Traffic↗

Concept for an off-line gain stabilisation method.

Conceptual ideas are presented for an off-line gain stabilisation method for spectrometry, in particular for alpha-particle spectrometry at low count rate. The method involves list mode storage of individual energy and time stamp data pairs. The 'Stieltjes integral' of measured spectra with respect to a reference spectrum is proposed as an indicator for gain instability. 'Exponentially moving averages' of the latter show the gain shift as a function of time. With this information, the data are relocated stochastically on a point-by-point basis.

Algorithms↗

Circadian modulation of performance on an aversion-based place learning task in hamsters.

In golden hamsters, the expression of a reward-conditioned place preference (CPP) is regulated in a circadian pattern such that the preference is exhibited strongly at the circadian time of prior training but not at other circadian times. We now report that the same "time-stamp" phenomenon is expressed following context conditioning with an aversive stimulus (conditioned place avoidance, CPA). Animals that were trained at a specific circadian time to discriminate between a "safe" context and one paired with foot shock, showed strong avoidance of the paired context at 24 and 48 h following the last training session, and showed no avoidance at 32 and 40 h following training. Circadian time is a feature that is learned during conditioning even though timing itself is not an explicit discriminative cue in these experiments. The results suggest that in hamsters, the emotional valence associated with the place where arousing stimulation (rewarding and aversive) is encountered is highest at the circadian time of occurrence. The golden hamster may be predisposed to anticipate the recurrence of arousing events at circa-24 h intervals.

Animals↗

Non-capsid proteins to identify foot-and-mouth disease viral circulation in cattle irrespective of vaccination.

The ability of foot-and-mouth disease virus (FMDV) to establish subclinical and even persistent infection, the so called carrier state, imposes the need to reliably demonstrate absence of viral circulation, to monitor the progress of control measures, either during eradication programs or after reintroduction of virus in free areas. This demonstration becomes critical in immunized populations, because of the concern that silent viral circulation could be hidden by immunization. This concern originates from the fact that vaccination against foot-and-mouth disease (FMD) protects against clinical disease, but not necessarily against subclinical infection or establishment of the carrier state in cattle. A novel approach, developed and validated at PANAFTOSA during the 1990s, based on an immunoenzymatic system for detection of antibodies against non-capsid proteins (NCP) has proven valuable for monitoring viral circulation within and between herds, irrespective of the vaccination status. Antibodies against NCP are induced during infection but, in principle, not upon vaccination. The validation of this system led to its international recognition as the OIE index test. The fitness of this serosurvey tool to assess viral circulation in systematically vaccinated populations was demonstrated through its extensive application in most regions in South America. The experience attained in these regions supported the incorporation of the "free of FMD with vaccination" provisions into the OIE code. Likewise, it opened the way to alternatives to the "stamping out" policy. The results gave input to an old controversy related to the real epidemiological significance, if any, of carrier animals under the vaccination conditions in South America, and supported the development of recommendations and guidelines that are being implemented for serosurveys that go with control measures in vaccinated populations.

Animals↗

Ordered growth of neurons on diamond.

Diamond has a number of unique properties that make it an attractive electronic and bio-electronic material. Here we show the ordered growth of mammalian neurons, the principal electrogenic cells of the nervous system, on diamond. Proteins were specifically patterned on diamond surfaces by micro-contact printing. Mouse cortical neurons were then cultured on these substrates. Neuron adhesion and outgrowth was specific for those areas of the diamond that had been stamped with laminin, resulting in ordered growth of high resolution. Neurons survived in culture for the duration of the experiment, and laminin patterns were stable for at least 1 week in culture. The relative biocompatibility of diamond and the suitability of neuron interfacing with the hydrogen surface conductivity layer make this an interesting model for the formation of defined neuronal networks and for implants.

Adsorption↗

Patterned networks of mouse hippocampal neurons on peptide-coated gold surfaces.

Patterned networks of hippocampal neurons were generated on peptide-coated gold substrates prepared by microscope projection photolithography and microcontact printing. A 19 amino acid peptide fragment of laminin A (PA22-2) that includes the IKVAV cell adhesion domain was used to direct patterns of cell adhesion in primary culture. Microscale grid patterns of peptide were deposited on gold-coated glass cover slips by soft lithography using "stamps" fashioned from polydimethylsiloxane. Strong coordination bonding between gold atoms on the surface and the sulfur atoms of the N-terminal cysteine residues supported stable adhesion of the peptide, which was confirmed by immunofluorescence using anti-IKVAV antiserum. Dispersed hippocampal cells isolated from neonatal mouse pups were grown on peptide-patterned gold substrates for 7 days. Neurons preferentially adhered to peptide-coated regions of the gold surface and restricted their processes to the peptide patterns. Whole cell recordings of neurons grown in patterned arrays revealed an average membrane potential of -50 mV, as well as the presence of voltage-gated ion conductances. Peptide-modified gold surfaces serve as convenient and effective substrates for growing ordered neural networks that are compatible with existing multi-electrode array recording technology.

Animals↗

Patterning cells in highly deformable microstructures: effect of plastic deformation of substrate on cellular phenotype and gene expression.

We describe the fabrication of deformable microstructures by low-pressure-soft-microembossing (muSEmb) that provides in vitro experimental "test-beds" to investigate the interplay of mechanical and chemical stimuli on cell behavior in a highly controlled environment. Soft microembossing exploits the softness and plasticity of parafilm to fabricate microstructures by pressing a silicon master or an elastomeric poly(dimethylsiloxane) stamp into the parafilm. We demonstrate that a protein-resistant comb polymer can be printed into the raised features of the embossed microstructures, which imparts protein, and hence cell resistance to those regions of the microstructures. These two features of our fabrication methodology-microembossing followed by spatially selective transfer of a nonfouling polymer-forms the core of our strategy to pattern cells within the parafilm microstructures, such that the cells are confined within bottoms of the microstructures. Cell culture experiments demonstrated the preferential cell attachment of NIH 3T3 fibroblasts to the fibronectin (FN) micropatterns by immunofluorescence microscopy. The actin cytoskeleton realigned along the axis of applied mechanical stress, and stretched cells showed altered gene expression of cytoskeletal and matrix proteins in response to mechanical deformation. The use of parafilm as a substrate and muSEmb as a fabrication method provides a simple and widely accessible methodology to investigate cellular behavior under well-defined conditions of plastic deformation and surface ligand density.

Animals↗

Rapid localized cell trapping on biodegradable polymers using cell surface derivatization and microfluidic networking.

Spatial control over cell attachment is essential for controlling cell behavior and engineering cell-based sensor arrays. Here we report on a patterning procedure that can be utilized on a wide range of adherent and non-adherent cell types without the need to identify the exact peptide sequence or extracellular matrix (ECM) necessary for optimal cell attachment. This is achieved by converting native sialic residues present on the surface of most cells into non-native aldehydes using a mild sodium periodate treatment. The aldehyde groups are then reacted with biotin hydrazide to produce biotinylated cells. Avidin is patterned onto the surface of a biotinylated biodegradable block copolymer, polylactide-poly(ethylene glycol)-biotin (PLA-PEG-biotin) by microfluidic networking using a PDMS stamp. The biotinylated cells then bind specifically to the patterned avidin regions. The PEG that is presented from the PLA-PEG-biotin copolymer in the regions without avidin immobilization minimizes cell binding in the non-patterned regions.

Avidin↗

Stimulation of mu and delta opioid receptors induces hyperalgesia while stimulation of kappa receptors induces antinociception in the hot plate test in the naked mole-rat (Heterocephalus glaber).

The antinociceptive effects of highly selective mu (DAMGO), delta (DPDPE) and kappa (U-50488 and U-69593) opioid agonists were evaluated following intraperitoneal (i.p.) administration in the naked mole-rat. A hot plate test set at 60 degrees C was used as a nociceptive test and the latency to the stamping of the right hind paw (response latency) was used as the end-point. DAMGO (5-10 mg/kg) and DPDPE (2.5-5 mg/kg) caused a naloxone-reversible significant decrease in the mean response latency. Subcutaneous injection of naloxonazine (20 mg/kg) 24h prior to the administration of DAMGO (5 mg/kg) also blocked the reduction in the response latency observed when DAMGO was injected alone. On the contrary, U-50488 (2.5-5 mg/kg) or U-69593 (0.08 or 0.1 mg/kg) caused a naloxone-reversible significant increase in the mean response latency. These results showed that activation of mu or delta receptors caused hyperalgesia, whereas activation of kappa receptors caused antinociception in the hot plate test in naked mole-rat. This suggests that mu and delta receptors modulate thermal pain in a different way than kappa receptors in the naked mole-rat. It is not possible at the moment to point out how they modulate thermal pain as little is known about the neuropharmacology of the naked mole-rat.

Analgesics, Opioid↗

Bite force measurement in awake rats.

This report describes the implementation of bite force measurement in awake rats and software instruments (Spike 2 script programs) that quantify and analyze the bite force data. One script program employs user-defined control of threshold bite force, which allows an easy adjustment of target force prior to training the rat. Furthermore, the interactive program allows on-line control of threshold bite force at anytime during the training session. Upon detection of the bite force crossing the threshold, it automatically triggers the external water delivery system for reinforcement. Another script program detects successful biting attempts, compiles times stamps and force level for each attempted bite, and calculates the total number of bites, success rate and mean bite force per training session. Using the new methodology, we trained five adult rats to produce the bite force of 1300 g. Our results demonstrated that all rats achieved the target force with a similar time course and exhibited little variability in success rate and mean bite force. The script programs provided instant review and analyses of the captured data. These techniques simplify assessment of bite force in behaving rats.

Algorithms↗

Poly(ethylene glycol) micro-patterns as environmentally sensitive template for selective or non-selective adsorption.

Poly(ethylene glycol) (PEG), a hydrophilic and repulsive polymer to non-specific adsorption, was stamped onto carboxylic acid-enriched polymer surfaces using the micro-contact printing technique. The patterns are stabilized via hydrogen bonds. Areas printed with PEG were then shown to be non-adsorbed with fluorescein isothiocyanate (FITC)-labeled dextran, while the poly(methacrylic acid) (PMAA) regions could via hydrogen bonding. Due to this contrast, well defined dextran patterns were obtained. Tuned with pH and temperature, the PEG molecules could be detached from the surfaces, erasing the template. Moreover, ionization of PMAA at higher pH induced an abrupt transition to an extended conformation, weakening the interactions between PMAA and dextran. Not only the dextran patterns lose their spatial selectivity, but also the overall adsorption amount is much lower. The pH sensitivity was in a quite narrow range, i.e. around pH 5. As the hydrogen bonds are also temperature sensitive, the attach points of PEG molecules on the surfaces disappeared at higher temperature. For poly(acrylic acid) (PAA) photografted surfaces, the pH sensitivity was more complicated due to the formation of the compact complexes of PEG and PAA molecules.

Adsorption↗