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Study design: Retrospective cohort study. Objectives: This study investigates postoperative urinary retention (POUR) following posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) and the effects of postoperative analgesia and mobility on retention. Summary of background data: High opioid use and decreased postoperative mobility are proposed risk factors for retention in adults. There is a paucity of literature on POUR in the adolescent population undergoing surgery for AIS. The impact of pain control and mobility on POUR in these patients is unknown. Methods: A retrospective cohort study was conducted of adolescents (11–18 years) undergoing elective PSF for AIS at a single institution (2012–2018). POUR was defined as the inability to void > 8 h after catheter removal. Possible risk factors for retention including opioid usage and ambulatory status at the time of catheter removal were assessed on univariate and binomial logistic regression analyses. Results: One hundred and thirty-six patients were included, with 21 (15.4%) experiencing POUR. On the day of catheter removal, 24 patients had not attempted ambulation; these patients had 2.5 times higher rate of POUR than those who were walking (30% vs. 12%, p= 0.04). Patients who developed retention ambulated a mean threefold shorter distance than those without POUR (45 vs. 136 feet, p= 0.04). On binomial logistic regression, decreased ambulation distance was associated with retention (p= 0.038). While opioid use was not significant on univariate analysis, higher opioid use on the day of catheter removal predicted retention on logistic regression (p= 0.001). POUR resolved in all patients (median duration 0.5 days, range 0–12 days). Conclusions: The development of POUR after PSF for AIS affects one in six patients but resolves quickly. Non-ambulatory patients and patients who received large doses of opioids on the day of catheter removal were more likely to develop POUR. Level of evidence: III.

Acute appendicitis is the most common surgical emergency in children. Differentiation of acute appendicitis from conditions that do not require operative management can be challenging in children. This study aimed to identify the optimum risk prediction model to stratify acute appendicitis risk in children.

PURPOSE: To characterize the population of ventilator-dependent patients transferred to long term hospitals (LTHs) for continued weaning from prolonged mechanical ventilation (PMV). METHODS: De-identified data from 22 hospitals were submitted [...]

The article presents a discussion on the involvement of the U.S. Navy in the historic siege and reduction of Fort Pulaski, Georgia on April 10-11, 1862 contrary to the general reports about it. It presents historical evidence, including military reports and correspondence, of the U.S. Navy providing equipment, intelligence, manpower, supplies and transport for the siege.

There are three main approaches to the representationof temporal information in AI literature: theso-called method of temporal argumentsthatsimply extends functions and predicates of first-orderlanguage to include time as the additional argument;modal temporal logicswhich are extensions ofthe propositional or predicate calculus with modaltemporal operators; and reified temporal logicswhich reify standard propositions of some initiallanguage (e.g., the classical first-order or modallogic) as objects denoting propositional terms. Theobjective of this paper is to provide an overview onthe temporal reified approach by looking closely atsome representative existing systems featuring reifiedpropositions, including those of Allen, McDermott,Shoham, Reichgelt, Galton, and Ma and Knight. We shalldemonstrate that, although reified logics might bemore complicated in expressing assertions about somegiven objects with respect to different times, theyaccord a special status to time and therefore haveseveral distinct advantages in talking about someimportant issues which would be difficult (if notimpossible) to express in other approaches.

Peroxisome proliferator-activated receptor alpha (PPAR alpha)-null mice were used to investigate the nature of the relationship between the normal circadian rhythm of hepatic PPAR alpha expression and the expression of the lipogenic and cholesterogenic sterol regulatory element-binding protein (SREBP)-regulated genes, acetyl-CoA carboxylase, fatty acid synthase (FAS), and 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoAR). The expression of FAS and HMG-CoAR varied rhythmically over the diurnal cycle in the normal mice, with patterns that were the opposite of that of PPAR alpha. The diurnal variation of lipogenic and cholesterogenic gene expression was attenuated or abolished in the PPAR alpha-null mice. This resulted in decreased expression compared with normal mice, but only during the dark phase of the cycle, when food intake was high. The diurnal variation in hepatic fatty acid and cholesterol synthesis was also abolished in the PPAR alpha-null animals and the variations in the concentration of plasma triacylglycerol, nonesterified fatty acids, and cholesterol were all attenuated. The failure of HMG-CoAR expression to increase during the feeding period in the PPAR alpha-null mice was associated with a decrease in hepatic nonesterified cholesterol content and an increase in cholesteryl ester compared with normal mice. There was no defect in the downregulation of hepatic HMG-CoAR mRNA in response to dietary cholesterol in the PPAR alpha-null mice. Under these conditions, hepatic PPAR gamma expression increased in both the control and PPAR alpha-deficient mice. The results suggest that PPAR alpha-deficiency disturbs the normal circadian regulation of certain SREBP-sensitive genes in the liver, but does not affect their response to dietary cholesterol. -- Patel, D. D., B. L. Knight, D. Wiggins, S. M. Humphreys, and G. F. Gibbons. Disturbances in the normal regulation of SREBP-sensitive genes in PPAR alpha-deficient mice. J. Lipid Res. 2001. 42: 328--337.

A typical functional region in cortex contains thousands of neurons, therefore direct neuronal simulation of the dynamics of such a region necessarily involves massive computation. A recent efficient alternative formulation is in terms of kinetic equations that describe the collective activity of the whole population of similar neurons. A previous paper has shown that these equations produce results that agree well with detailed direct simulations. Here we illustrate the power of this new technique by applying it to the investigation of the effect of recurrent connections upon the dynamics of orientation tuning in the visual cortex. Our equations express the kinetic counterpart of the hypercolumn model from which Somers et al(Somers  D, Nelson S and Sur M 1995 J. Neurosci.155448––65) computed steady-state cortical responses to static stimuli by direct simulation. We confirm their static results. Our method presents the opportunity to simulate the data-intensive dynamical experiments of Ringach et al(Ringach D, Hawken M and Shapley R 1997 Nature387281––4), in which 60 randomly oriented stimuli were presented each second for 15  min, to gather adequate statistics of responses to multiple presentations. Without readjustment of the previously defined parameters, our simulations yield substantial agreement with the experimental results. Our calculations suggest that differences in the experimental dynamical responses of cells in different cortical layers originate from differences in their recurrent connections with other cells. Thus our method of efficient simulation furnishes a variety of information that is not available from experiment alone.

AbstractThis paper describes the successful bulk heat-treatment of wooden artifacts infested with furniture beetle Anobium punctatumand death watch beetle Xestohium rufovillosum, without direct humidity control. A chamber was constructed in a store and equipped with four fan-assisted heaters. Core temperatures of between 52 and 55°C were achieved after heating the chamber for eight hours. The heating and cooling cycles were completed over 23 hours. The relative humidity (RH) remained acceptable, ranging from 43 to 75% depending on the location of the sensors. However, the RH inside three sealed bags containing fragile objects was unacceptably high. Equilibrium moisture content and dimensional movement of one object were measured, indicating minimal movement. All live insects, including furniture beetle and death watch beetle in the infested timbers, were killed by the treatment.

Contact-evoked changes in EMG activity during human grasp. 2215 Cutaneous receptors in the digits discharge bursts of activity on contact with an object during human grasp. In this study, we investigated the contribution of this sensory activity to the responses of muscles involved in the task. Twelve subjects performed a standardized precision grasp task without the aid of vision. Electromyographic (EMG) responses in trials when the object was present were compared with those in which the object, and hence the associated afferent responses, were unexpectedly absent. Significant differences in EMG amplitude occurred in the interval 50–100 ms after contact in all subjects and in 33/46 of the muscles sampled. The differences emerged as early as 34 ms after contact and comprised as much as a fourfold change in EMG from 50 to 100 ms after contact with the object. Typically, EMG responses were larger when the object was present (OP), though there were cases, particularly in the thenar muscles, in which the responses increased when the object was absent (OA). Local anesthesia of the thumb and index finger attenuated contact-evoked EMG activity in at least one muscle in all four subjects tested. In one subject, contact-evoked responses were abolished completely during the anesthesia in all four muscles sampled. The results indicate that the sensory activity signaling contact plays a key role in regulating EMG activity during human grasp. Much of this feedback action is attributable to cutaneous receptors in the digits and probably involves both spinal and supraspinal pathways.

Presented in this paper are the initial results involving the use of trachea temperatures as a means of determining the post-mortem period. A simple mathematical model is developed based on the cooling curves of five corpses. Errors between actual and calculated post-mortem periods may be due to an initial temperature plateau or lack of knowledge of body temperature at time of death.

Using non-identifiable data supplied by the Department of Health and Social Security (DHSS), claims for state social security benefits by fathers and sons were compared. Criminal records of the same fathers and sons were also compared. It is concluded that the habit of making unusually frequent social security claims is transmitted from one generation to the next, and is a characteristic feature of the delinquent minority.

We analyze the kinetics of a pigment system with thermal and photochemical transitions among its states. The general mathematical description is obtained and is then specialized to systems with two stable states (states with negligible thermal outlets) in which the total amount of pigment is conserved. We describe the properties of the pigment state populations and of their kinetics in not-too bright lights. The wavelength dependence of the population distribution following saturating light is called the saturation spectrum. The populations are shown to relax to this saturation distribution exponentially with amount of light; the wavelength dependence of the relaxation constant is called the relaxation spectrum. The specialized description of the pigment kinetics is applied to the six-state, two-stable-state model of Minke et al. (1974) for the barnacle visual pigment. The immediate spur for this analysis was a problem which has recently become acute: That of deciding between a single bistable pigment system and two separate systems as the possible origin of various abnormally-shaped or nonmatching action or absorption spectra or wavelengthdependent response forms which have been observed in many invertebrate photoreceptors. We show that these two possibilities may be distinguished quite generally by saturation and relaxation measurements, and describe such measurements in the following article.

We examine consequences of image-forming inhomogeneity in the form of a point-spread function that changes with position on the image plane. The familiar self-replicating sinusoids, which a homogeneous system simply multiplies by its spatial modulation-transfer function, generalize to eigenfunctions, which the system multiplies by eigenvalues. We give a way to calculate the eigenfunctions and eigenvalues from the variable point-spread function. We illustrate this with data from the visual system and show that these lead to a discrete set of most-sensitive eigenfunctions, which we construct.

Two methods are described for the assay of low-density-lipoprotein (LDL) receptor protein based on the binding of receptor to microtitre plate wells coated with a specific monoclonal antibody or with LDL, followed by detection with radioactive antibody that recognizes a different part of the molecule. The two-antibody procedure detected approx. 2 ng of pure bovine receptor at twice background, and there was a linear relationship on a double-logarithm plot between radioactive antibody bound and the amount of receptor added, up to at least 500 ng of receptor protein per well. The procedure using immobilized LDL was less sensitive and the binding of receptor was inhibited by low concentrations of NaCl, which restricted its usefulness for routine assay of tissue extracts. LDL receptor protein could be readily assayed using the two-antibody procedure in normal human skin fibroblast extracts prepared by bulk-elution from small columns of DEAE-cellulose followed by rapid desalting. No radioactive antibody bound with extracts of cells from a receptor-negative familial hypercholesterolaemic subject. The LDL receptor content of normal fibroblasts preincubated with lipoprotein-deficient serum was estimated, using bovine receptor as standard, to be approx. 60 ng of receptor protein/mg of cell protein.

A new technique has been developed to identify low-density-lipoprotein (LDL) receptors on nitrocellulose membranes, after transfer from SDS/polyacrylamide gels, by ligand blotting with biotin-modified LDL. Modification with biotin hydrazide of periodate-oxidized lipoprotein sugar residues does not affect the ability of the lipoprotein to bind to the LDL receptor. Bound lipoprotein is detected with high sensitivity by a streptavidin-biotin-peroxidase complex, and thus this method eliminates the need for specific antibodies directed against the ligand. The density of the bands obtained is proportional to the amount of pure LDL receptor protein applied to the SDS/polyacrylamide gel, so that it is possible to quantify LDL receptor protein in cell extracts. Biotin can be attached to other lipoproteins, for example very-low-density lipoproteins with beta-mobility, and thus the method will be useful in the identification and isolation of other lipoprotein receptors.

Membranes prepared from cultured fibroblasts were assayed for acyl-coenzyme A: cholesterol acyltransferase (ACAT) by a method that relied exclusively on the cholesterol already present on the membranes as the sterol substrate. Changes in membrane ACAT activity during incubation of fibroblasts under a variety of conditions were similar to the changes in the rate of incorporation of oleic acid into cholesteryl esters by the intact cells. The addition of low-density lipoprotein (LDL) to fibroblasts pre-incubated with lipoprotein-deficient serum led to a transient increase in membrane ACAT activity, which reached its peak after 7h and was related to the receptor-mediated uptake and degradation of the lipoprotein by the cells. However, after incubation of the membranes with a cholesterol-rich donor lipoprotein, which resulted in an equilibration of cholesterol between membranes and donor, each preparation exhibited the same activity. In contrast with these effects of LDL, incubation of the cells with non-esterified cholesterol produced a prolonged increase in ACAT activity and an increase in the activity observed after equilibration. Furthermore, ACAT activity in cells grown with linoleic acid was higher, both before and after the addition of LDL, than that of cells grown in normal medium or with palmitate. The increase in activity produced by LDL was also greater, reflecting the greater rate of degradation of LDL by the cells, and was associated with an increase in the activity observed after equilibration with donor. The results suggest that although fibroblasts can increase the amount of active enzyme on their membranes to accommodate an exceptionally high or prolonged supply of cholesterol, under normal circumstances the increase in membrane ACAT activity produced by LDL can be explained entirely by an increase in the amount of cholesterol in the substrate pool.

Human blood monocyte-derived macrophages that had been cultured for 7 days in the presence of 20% whole human serum exhibited saturable degradation of low-density lipoprotein (LDL). This degradation could be abolished by pre-incubating the cells with a high concentration of LDL in the medium and increased by pre-incubating the cells in medium containing lipoprotein-deficient serum. Cells obtained from the blood of homozygous familial-hypercholesterolaemic (FH) patients only exhibited a low rate of non-saturable degradation of LDL, even when pre-incubated without lipoproteins. Thus the saturable degradation of LDL by normal cells was mediated by the LDL receptors that are defective in FH patients and little LDL was taken up and degraded through any of the other endocytotic processes present in macrophages. Degradation by normal cells pre-incubated with lipoprotein-deficient serum had a higher apparent affinity for LDL than that of cells maintained in whole serum, which suggests that incubation with lipoprotein-deficient serum may not only induce the formation of LDL receptors but may also have a direct effect on the receptors themselves. Monocyte-derived macrophages from normal and FH subjects showed similar saturable degradation of acetylated LDL and also of LDL complexed with dextran sulphate. Maximal degradation of each was in the same range as the degradation of unmodified LDL by normal cells, and was not increased if the cells were pre-incubated with lipoprotein-deficient serum.

The nonlinear performance of a single-nut, preloaded ball screw actuator is analyzed in this paper. The study identifies the source of nonlinear torque in the ball screw and subsequently maps that torque into the nonlinear displacement response due to windup in the shaft. The study is complemented with an experimental verification using a small angle rotation fixture (ARC) to input very small amplitude angular displacements to the screw while measuring induced torque and displacements. The experimental results are obtained from a Precision Linear Optimization Testbed (PLOT) which was developed to study the ability of different actuator systems to provide long range motion with nanometer accuracy. The analysis is conducted for the case of no axial loading. The study shows that the nonlinearities in the ball screw originate in the rolling friction between the balls and the races which induces torque in the nut and subsequently windup in the shaft. It also shows that the torque can be deduced from a relationship of the torque between a ball spinning in a race.

The clinical expression of disease in patients with conditions in which autoimmunity is thought to contribute to the pathogenesis of disease is the result of an unfortunate combination of predisposing and environmental factors. The presence of autoantibodies showing a variety of antigen specificities in sera from many of these patients has been closely correlated with particular spectra of organ involvement or tissue destruction. Their precise role in the disease process is as yet unclear. Sera from patients with paraproteinaemia also often contain autoantibodies to a variety of cell components, although symptoms of autoimune disease are rarely found in this group of individuals. In this study of 42 sera from patients with paraproteinaemia we have confirmed the presence of autoantibodies in 33% (13/42) of samples. Amongst the autoantibodies detected were those to human neutrophils (3), U1RNP (8) and cardiolipin (4). In five sera, the immunoglobulin class of autoantibody did not correlate with that of the monoclonal band. This study extends previous reports of the repertoire of autoantibodies present in sera from patients with paraproteinaemia.

Subthreshold solutions of the Hodgkin-Huxley equations are considered here by means of the linearized forms of these equations. An asymptotic theory is obtained, based on dimensional analysis and scaling arguments. Explicit expressions for the crest speed are obtained and are shown to be in good agreement with experiment, with computation, and with an exact asymptotic value which is also obtained here.

Treatment of normal fibroblasts with the bifunctional cross-linking reagent DTSSP [3,3′-dithiobis(sulphosuccinimidylpropionate)] at 4 degrees C converted approximately 40% of the cell-surface low-density lipoprotein (LDL) receptors into a high-M(r) form, thought to represent receptor dimers. Preincubation of the cells with anti-(LDL receptor) monoclonal antibody 10A2 increased the proportion of surface receptors in the high-M(r) form after treatment with DTSSP at 4 degrees C to over 70%. Preincubation with LDL did not affect the proportion cross-linked, but prevented the increase produced by antibody 10A2. Cross-linking at 37 degrees C was less efficient than at 4 degrees C and was not affected by preincubation with antibody 10A2. Surface LDL receptors on fibroblasts from the homozygous familial hypercholesterolaemic subject MM were not cross-linked by DTSSP, confirming that the mutation had produced a change in the conformation of the receptor molecule. Taken together, the results suggest that normal LDL receptors on at least one region of the surface membrane may be loosely associated in some form of multimeric array which alters its alignment differently in response to antibody 10A2 and to cooling. Mutations that alter the tertiary structure of the receptors could affect LDL binding by disturbing the arrangement of the array.

Two novel mutations of the low density lipoprotein (LDL)-receptor gene were found in two Italian familial hypercholesterolemia (FH)-heterozygotes. The first mutation was an 18 nucleotide duplication in exon 8 which is preceded by an A-->T transversion. The translation product of the mutant allele was predicted to be a receptor with an in-frame insertion of 6 amino acids in repeat B of the epidermal growth factor precursor homology domain. Analysis of LDL-receptor activity in the proband's fibroblasts showed a 50% reduction of 125I-labeled LDL binding and pulse-chase studies suggested that little, if any, of the mutant protein was processed to the mature form. The second mutation was a 7 kb duplication (from intron 2 to intron 6) of exons 3 through 6, predicted to encode an elongated receptor with the duplication of repeats 2-7 of the ligand binding domain. The elongated receptor was processed slightly more slowly than the normal receptor, but was converted to a mature form of the expected size. This mature, mutant receptor was degraded more rapidly than the normal receptor. On ligand blotting the elongated receptor bound twice as much LDL or beta-very low density lipoprotein (betaVLDL) as the normal receptor. In contrast, maximum binding of LDL to proband's cells was decreased to approximately 70% of the normal cells with a significant increase in apparent affinity. Cell association at 37 degrees C, internalization, and degradation showed a similar reduced maximum. Thus these mutations demonstrate that duplications of amino acid sequences in the low density lipoprotein LDL-receptor may disrupt the LDL-receptor pathway at different levels.

Plasma concentrations of the atherogenic lipoprotein(a) (Lp(a)) are predominantly determined by inherited sequences within or closely linked to the apolipoprotein(a) gene locus. Much of the interindividual variability in Lp(a) levels is likely to originate at the level of apo(a) gene transcription. However, the liver-specific apo(a) basal promoter is extremely weak and does not exhibit common functional variations that affect plasma Lp(a) concentrations. In a search for additional apo(a) gene control elements, we have identified two fragments with enhancer activity within the 40-kilobase pair apo(a)-plasminogen intergenic region that coincide with DNase I-hypersensitive sites (DHII and DHIII) observed in liver chromatin of mice expressing a human apo(a) transgene. Neither enhancer exhibits tissue specificity. DHIII activity was mapped to a 600-base pair fragment containing nine DNase I-protected elements (footprints) that stimulates luciferase expression from the apo(a) promoter 10-15-fold in HepG2 cells. Binding of the ubiquitous transcription factor Sp1 plays a major role in the function of this enhancer, but no single site was indispensable for activity. DHIII comprises part of the regulatory region of an inactive long interspersed nucleotide element 1 retrotransposon, raising the possibility that retrotransposon insertion can influence the regulation of adjacent genes. DHII enhancer activity was localized to a 180-base pair fragment that stimulates transcription from the apo(a) promoter 4-8-fold in HepG2 cells. Mutations within an Sp1 site or either of two elements composed of direct repeats of the nuclear hormone receptor half-site AGGTCA in this sequence completely abolished enhancer function. Both nuclear hormone receptor elements were shown to bind peroxisome proliferator-activated receptors and other members of the nuclear receptor family, suggesting that this enhancer may mediate drug and hormone responsiveness.

The objective of the paper is to provide a taxonomy of temporal systems according to three fundamental considerations: the assumed axiomatic theory, the expressiveness, and the mechanisms for inference which are provided. There is an discussion of the significance of the key features of the taxonomy for computer modelling of temporal events. A review considers the most significant representative systems with respect to these issues, including those due to Bruce, Allen and Hayes, Vilain, McDermott, Dechteret al., Kahn and Gorry, Kowalski and Sergot, Bacchuset al., and Knight and Ma. A tabular comparison of systems is given according to their main structural features. In conclusion, the characteristics of a general axiomatic system capable of representing all the features of these models is discussed.