Significant Decrease In Slope Research Articles

Effect of police action on low-barrier substance use disorder service utilization

BackgroundPolice action can increase risky substance use patterns by people who use drugs (PWUD), but it is not known how increased police presence affects utilization of low-barrier substance use disorder bridge clinics. Increased police presence may increase or decrease treatment-seeking behavior. We examined the association between Operation Clean Sweep (OCS), a 2-week police action in Boston, MA, and visit volume in BMC’s low-barrier buprenorphine bridge clinic.MethodsIn this retrospective cohort, we used segmented regression to investigate whether the increased police presence during OCS was associated with changes in bridge clinic visits. We used General Internal Medicine (GIM) clinic visit volume as a negative control. We examined visits during the 6 weeks prior, 2 weeks during, and 4 weeks after OCS (June 18–September 11, 2019).ResultsBridge clinic visits were 2.8 per provider session before, 2.0 during, and 3.0 after OCS. The mean number of GIM clinic visits per provider session before OCS was 7.0, 6.8 during, and 7.0 after OCS. In adjusted segmented regression models for bridge clinic visits per provider session, there was a nonsignificant level increase (0.643 P = 0.171) and significant decrease in slope (0.100, P = 0.045) during OCS. After OCS completed, there was a significant level increase (1.442, P = 0.003) and slope increase in visits per provider session (0.141, P = 0.007). There was no significant change in GIM clinic volume during the study period.ConclusionsThe increased policing during OCS was associated with a significant decrease in bridge clinic visits. Following the completion of OCS, there was a significant increase in clinic visits, suggesting pent-up demand for medications for opioid use disorder, a life-saving treatment.

Arterial Baroreceptor Physiology: Differences Between Normal Subjects and Pediatric Patients with Postural Tachycardia and Neurocardiogenic Syncope

The arterial baroreceptor reflex in children and adolescents has not been well studied in the current literature with a lack of agreed upon normal values, particularly in postural orthostatic tachycardia syndrome (POTS) or neurocardiogenic syncope (NCS). We used the sequence method and head-up tilt test (HUTT) to evaluate baroreceptor function in 3 phases: baseline supine position for 10min, head-up position at 70° for 30min or until syncope, and post-tilt supine reposition for 10min. We measured the number of baroreceptor events, baroreceptor effectiveness index (BEI), and the magnitude of sensitivity of the events at each phase of HUTT. We studied 198 individuals (49 normal subjects, 67 POTS, 82 NCS) with age ranges from 8 to 21years. The data show a statistically significant decrease in slope and BEI in patients with POTS and NCS during the head-up phase, with an increase in activity in the lag 1 and 2 portions of all phases in patients with POTS. This study provides terminology to describe baroreceptor function and identifies the slope and BEI portions of the baroreceptor reflex as the most useful objective measures to differentiate pediatric patients with POTS and NCS from normal subjects.

Beta-adrenergic glaucoma drugs reduce lymphatic clearance from the eye: A sequential photoacoustic imaging study

Our study aims to determine whether the beta-adrenergic system is involved in the regulation of lymphatic drainage from the eye. For this purpose, we assessed the effect of 2 topical beta-adrenergic blockers, timolol and betaxolol, commonly used as glaucoma drugs, on lymphatic clearance of albumin from the aqueous humor to neck lymph nodes. Adult mice were treated with either topical timolol, a non-selective β-blocker, 0.5% (n = 8), or topical betaxolol, a selective β1-adrenergic blocker, 0.5% (n = 6) twice daily for 14 days and compared to respective control groups (n = 5 and n = 7). Changes in lymphatic clearance from the eye were assessed using a quantitative in vivo photoacoustic imaging approach. In all subjects, right eye and neck lymph nodes were longitudinally assessed by sequential photoacoustic imaging just prior to near-infrared dye injection into the anterior chamber of the eye, and 20 min, 2 and 4 h after injection. Repeat measurements of mean pixel intensities (MPIs) of right eyes and nodes were performed at all timepoints. The areas under the curves (AUC) were calculated and the AUC of the treated-group was compared to that of controls using the Mann-Whitney U test. The slopes of MPI of each region of interest over time were compared using the linear mixed model after adjusting for IOP decrease after treatment and other parameters such as sex and body weight. In the timolol-treated group, right neck nodes showed significant decrease in AUC signal intensity compared with controls (P = 0.003), and significant decrease in slope of MPI compared with controls (P = 0.0025). In the betaxolol-treated group, right neck nodes showed significant decrease in AUC signal intensity compared with controls (P = 0.02), and significant decrease in slope of MPI compared with controls (P = 0.0069).Topical treatment with timolol and betaxolol reduced lymphatic clearance of albumin from the aqueous humor to the neck lymph nodes. This finding may be relevant for the management of secondary glaucomas and inflammatory eye disease in which the clearance of accumulated proteins and antigen from the eye is important to disease recovery and sight protection. This study suggests that the beta-adrenergic system plays a role in the regulation of lymphatic clearance from the eye.

MO188RECONSIDERING THE EDELMAN EQUATION: IMPACT OF INDIVIDUAL TOTAL BODY CATION CONTENT AND BODY WEIGHT

Abstract Background and Aims Treatment of dysnatremias is guided by formulas that are based on the Edelman equation, including Adrogue-Madias’ and others. Edelman’s equation is the result of a unique study in which serum sodium concentration ([Na+]), total body exchangeable sodium (Nae+) and potassium (Ke+) and total body water (TBW) were measured in a highly heterogeneous population. Because these observations resulted from steady state observations, the equation might not account for the recently uncovered highly dynamic Na+ body compartment where Na+ is temporarily stored and released without affecting TBW. Various factors that influence this Na+ body compartment have been identified and we questioned as to what extent these factors affect associations between serum [Na+] and [Nae+Ke]/TBW. Method We performed a post-hoc analysis of original data published by Edelman. In the linear regression model, effects of sex, edema (y/n), age and body weight (>/< median split) were examined. Serum [Na+] was calculated by multiplying serum water [Na+] of the original data set by 0.93. Using piecewise regression, we analyzed differences in slope and y-intercept for the regression between serum [Na+] and increasing values of (Nae+Ke)/TBW, in which the clinical characteristics from the subgroups were included as interaction factors . Results Data was available for 85 measurements in 82 patients; 57 males and 25 females. The median age (range) age was 58 (27-90) years and median weight (range) was 59.6 (36.4 – 168.2) kilograms. Median serum [Na+] (range) was 131.4 (103.4 – 150.2) mmol/L. The association between serum [Na+] and (Nae+Ke)/TBW was different for high and low weight categories (figure 1A). Sex, age or presence of edema did not alter the relationship. Piecewise regression showed a significant decrease in slope in the regression between serum [Na+] and (Nae+Ke)/TBW above 149 mmol/L (Nae+Ke)/TBW (figure 1B). Conclusion Edelman equation’s coefficients are significantly affected by weight and total body cation content. In subjects with a low weight and low total body cation content, the Edelman equation seems to adequately predict the course of serum [Na+]. However, the clinical use of the Edelman-based formulas may be hampered in subjects with higher weight and higher total body cation content, which may reflect increased tissue Na+ storage. Our analysis underlines the importance of further research into the role of osmotically inactive Na+ storage in osmoregulation.

Effect of Payor-Mandated Review of Prescription Drug Monitoring Program on Opioid Prescriber Rates

To evaluate the effect of a 2016 South Carolina payor mandate to query the state prescription drug monitoring program (PDMP) before prescribing controlled substances on the rate of opioid prescribers in South Carolina. South Carolina PDMP datasets from 2010-2017 were evaluated using interrupted time series regression to compare changes in the rate of opioid prescribers before and after the 2016 mandate. The rate of opioid prescribers was defined as the number of prescribers who prescribed class II to IV opioids on any one prescription in each quarter divided by the total number of South Carolina prescribers who prescribed any one class II to IV medication. The rate of high-dose opioid prescribers was defined as the number of prescribers who prescribed ≥90-morphine milligram equivalent per day on any one prescription in each quarter divided by all of the prescribers who prescribed an opioid analgesic prescription. The rates of South Carolina opioid prescribers decreased from 75% in 2010 to 60% in 2017, with no significant change in slope (P = 0.24) after the 2016 payor mandates. The rates of South Carolina high-dose opioid prescribers decreased from 40% in 2010 to 32% in 2017, with a significant decrease in slope (P < 0.001) after the payor mandate. The slope of the South Carolina high-dose opioid prescriber rate significantly decreased after the 2016 South Carolina payor mandate, while the slope of the South Carolina opioid prescriber rate did not. The long-term outcomes related to the change in opioid prescriber rates are unknown and warrant further study.

Mechanisms of Orthopnea in Stable Obese Subjects.

The present study explored the role of closing volume as a determinant of orthopnea in stable obese subjects. We hypothesized that: (1) increase in closing volume in supine position would be greater in orthopneic than in non-orthopneic subjects, and (2) the relationship of change in closing volume to change in dyspnea with position would be dependent on expiratory flow limitation in the sitting position. In stable obese subjects, in sitting and supine positions, we measured the Borg dyspnea score, static lung volumes, expiratory flow limitation during tidal breathing, and single-breath nitrogen expiration test. From the latter, we determined closing volume and closing capacity, slope of phase III, and opening capacity. Orthopnea was defined as any increase in the Borg score in the supine position from its value in the sitting position. Twenty-one subjects (13 women), median age (interquartile range) 55 (49-57) y and with body mass index of 39 (38-42) kg/m(2) were included, of whom 12 were orthopneic and 11 had expiratory flow limitation while seated. In the sitting position, orthopneic and non-orthopneic subjects were similar for age, body mass index, and pulmonary function tests, including single-breath nitrogen expiration test-derived variables. In the orthopneic subjects, there were no changes in any respiratory variable between positions. In the non-orthopneic subjects, there was a significant decrease in slope of phase III in the supine position from 1.67 (1.33-3.60) to 1.40 (1.25-1.66)%/L (P = .008). Overall, the subjects' Borg score significantly correlated with the slope of phase III (r = 0.63, P = .002) and opening capacity (r = -0.47, P = .03). In 10 subjects without expiratory flow limitation, it correlated with slope of phase III (r = 0.68, P = .03). In stable obese subjects, magnitude of orthopnea correlated with an increase in the slope of phase III in subjects without expiratory flow limitation. Expiratory flow limitation should be taken into account in obese patients.

Responses of iliac conduit artery and hindlimb resistance vessels to luminal hyperfructosemia in the anaesthetized pig

High fructose levels are found in diabetes mellitus, associated with high corn syrup diets, and have been claimed to cause hypertension. As the direct effects on conduit and resistance arteries have not been previously reported, we measured these in vivo in the anaesthetized pig with instrumented iliac arteries. Experiments were performed on the iliac artery preparation in the anaesthetized pig: blood flow, diameter and pressure were measured in the iliac. The change in diameter of an occluded iliac artery segment filled with hyperfructosemic (15 μm) blood was 89.5 ± 22.1 μm (mean ± SE), contrasted with 7.7 ± 13.06 μm control (P = 0.005, paired t-test, n = 6). There was no significant difference when compared with blood containing both hyperfructosemic blood and the nitric oxide synthesis inhibitor, N(G)-nitro-l-arginine methyl ester (250 μg mL(-1)). Step changes in pressure and flow were achieved by progressive arterial stenosis during control saline and 15 μm min(-1) fructose downstream intra-arterial infusions. Linear regression of the step changes in blood pressure versus the instantaneous step changes in blood flow showed a statistically significant decrease in slope of the conductance (P < 0.001, analysis of covariance), indicating an increase in instantaneous peripheral vascular resistance. Peripheral autoregulation and conduit artery shear-stress-mediated dilatation were not significantly altered. An elevated level of fructose caused dilatation of a conduit artery but constriction of resistance vessels. The latter effect could account, if maintained long-term, for the hypertension claimed to be due to hyperfuctosemia.

Determinants of change in airway reactivity over 11 years in the SAPALDIA population study

We investigated determinants of change in bronchial reactivity in the Swiss Cohort Study on Air Pollution and Lung Diseases in Adults (SAPALDIA), a population-based cohort with wide age range (29-72 yrs at follow-up). The role of sex, age, atopic status, smoking and body mass index (BMI) on percentage change in bronchial reactivity slope from the baseline value was analysed in 3,005 participants with methacholine tests in 1991 and 2002, and complete covariate data. Slope was defined as percentage decline in forced expiratory volume in 1 s from its maximal value per micromole of methacholine. Bronchial hyperreactivity prevalence fell from 14.3 to 12.5% during follow-up. Baseline age was nonlinearly associated with change in reactivity slope: participants aged <50 yrs experienced a decline and those above an increase during follow-up. Atopy was not associated with change, but accentuated the age pattern (p-value for interaction = 0.038). Smoking significantly increased slope by 21.2%, as did weight gain (2.7% increase per BMI unit). Compared with persistent smokers, those who ceased smoking before baseline or during follow-up experienced a significant decrease in slope (-27.7 and -23.9%, respectively). Differing, but not statistically different, age relationships and effect sizes for smoking and BMI between sexes were found. Mean bronchial reactivity increases after 50 yrs of age, possibly due to airway remodelling or ventilation-perfusion disturbances related to cumulative lifetime exposures.

A possible role for phospholipase A2 in the action of general anesthetics.

General anesthetics inhibit Ca(2+)-activated potassium (BK) channels at clinically relevant concentrations. This study examined the possibility that general anesthetics produce their effect on BK channels by disrupting the phospholipase A2 (PLA2)-arachidonic acid signal transduction pathway. Treatment of excised patches with exogenous arachidonic acid (2.5 microM) resulted in a 3.6 +/- 1.3-fold increase in BK channel activity. Subsequent exposure of these patches to concentrations of halothane (0.6 mM), ketamine (100 microM), or etomidate (10 microM) that would normally block the channel by approximately 60-80% in the absence of arachidonic acid did not reduce the channel activity. Arachidonic acid resulted in a significant increase in the 50% effective concentration for the ketamine dose-response curve from 3.4 +/- 0.4 to 693 +/- 379 microM (P < 0.001) as well as a significant decrease in slope from 1.40 +/- 0.21 to 0.59 +/- 0.05 (P < 0.001). The PLA2 inhibitors quinacrine (1 microM), aristolochic acid (250 microM), and octadecylbenzoylacrylic acid (7 microM) inhibited BK channels by 61 +/- 6, 47 +/- 2, and 30 +/- 9%, respectively, and in a manner indistinguishable from general anesthetics inhibition. Aristolochic acid and ketamine significantly inhibit the PLA2-mediated production of arachidonic acid in GH3 cells.

Effect of soil loosening on the hydraulic properties of a duplex soil

In a duplex, transitional red-brown earth, the relationships between hydraulic conductivity K, diffusivity D, soil water potential (�) and volumetric water content (�) in different soil layers were evaluated. Changes in these relationships and in the derived parameters; macroscopic capillary length and characteristic microscopic pore radius due to soil loosening were examined. Replicated large undisturbed and repacked cores of 0.75 m diameter and 1.35 m deep, located in a lysimeter, were used in this study. The K- � relationships were measured during steady upward flow from a watertable at different depths. The � � relationships were measured during a soil drying cycle. The undisturbed soil showed similar soil water characteristics (�-� curves) in all soil layers, at depths greater than 0.25 m. In contrast, K at high � was significantly lower in the upper subsoil, 'throttle' layer with high clay content, compared with the deeper soil layers. However, previous studies on a similar soil have also shown that factors other than pore size distribution, such as tortuosity and pore connectivity, markedly influence the hydraulic conductivity properties of clay soils. Coefficients in the log � on log� and in the log K(�) on log � relationships for all soil layers combined differed markedly from the coefficients for individual layers, indicating the need to measure these properties separately for different subsoil clay layers of this duplex soil. The repacking of the soil to a lower bulk density caused an increase in K at high � values. This was accompanied by a significant decrease in slope of the log � -log � relationship, from 17-21 to around 7, in the subsoil layers. The slope of the regression of log � - K(�) on log� changed from 24 in undisturbed soil to 9 in the repacked soil. This was mainly due to large changes in the � -�relationship, in combination with smaller changes in the K- � relationship. The decrease in diffusivity D with reduction in 0 was less marked in the repacked soil compared with the undisturbed soil. Thus, soil repacking shifted D(�) towards a constant value, for the range of � measured. This was mainly due to a slower rate of change in K with decrease in � on the repacked soil, combined with a compensating increase in d � /d� values. The calculated values of macroscopic capillary length decreased and characteristic pore radius increased, reflecting the changes in pore sizes and hydraulic conductivities due to soil loosening. However, at any given supply and antecedent �, the sorptivity was greater in the loosened soil due to larger changes in water content and hydraulic conductivities. The potential application of these soil properties in evaluating water flow in undisturbed or loosened soils is briefly discussed.

Effects on infarct size of reperfusion and pretreatment with beta-blockade and calcium antagonists.

The "mass of tissue at risk" and the myocardial infarct developed was studied in dogs subjected to either 24-h occlusion of the left anterior descending coronary artery or 2-h occlusion followed by 22-h reperfusion. The "mass of tissue at risk" was defined under anaesthesia at the time of occlusion using the microsphere technique. Twenty-four hours later the hearts were removed, sliced transversely and stained with 2,3,5-triphenyltetrazolium chloride to define the infarcted tissue. All myocardial tissue was mapped and cut into small pieces for weighing and radioactive counting. Radioactivity was present in all tissue, including the infarct. In the centre of the infarct, counts remained low and then increased very rapidly with distance just beyond the edge. Tissue at risk from infarction was taken as that with less than 15% of the peak left ventricular (non-ischaemic) counts. A linear relationship was found between the mass of the left ventricular infarct and the left ventricular "mass of tissue at risk". The effect of 22 hours reperfusion was examined by this method and expressed by a regression equation. There was a significant decrease in slope for the regression line of the reperfusion data, (p less than 0.05, analysis of covariance), indicating less infarcted tissue for each gram of underperfused tissue. None of the drug pretreatments explored had any effect on infarct size in the 24-h occlusion model. With reperfusion, propranolol and flunarizine diminished infarct size compared with reperfusion only (p less than 0.05 for reduced slope, the new slope being not significantly different from zero). The effect of diltiazem was not so marked. Thus infarct size can be reduced with pretreatment, as long as the myocardium is reperfused.

The Enrichment of Soil Phosphorus in Runoff Sediments

AbstractThe effect of varying soil physical and chemical properties, soil slope, rainfall intensity, and source on the enrichment of soil P in runoff was evaluated under simulated rainfall conditions. The enrichment of P in runoff increased with increased P additions. The P enrichment ratio (ER) of Bernow soil increased from 2.43 to 6.29 at P additions of 0 and 100 kg P/ha, respectively. As rainfall intensity and soil slope were increased, ER decreased correspondingly. A significant linear relationship between in (ER) and in (sediment discharge) was obtained for all treatments studied. Similar slopes were obtained for soils ranging in texture from a fine sandy loam (−0.233, Bernow soil) to a clay (−0.264 and −0.252 for Houston and Pullman soils, respectively) under similar experimental conditions. In addition, the slopes were not affected by soil P status as slopes of −0.233 and −0.276 at 0 and 100 kg P/ha additions, respectively, were obtained for Bernow soil. With an increase in energy of runoff and kinetic energy of rainfall, a significant increase in slope of the relationship between In (ER) and in (sediment discharge) was obtained. In contrast, a decrease in energy of rain as in the case of overland flow and increased soil cover, resulted in a significant decrease in slope. The data indicated that runoff and rainfall energy and soil P status have a greater effect on ER than soil physical properties. A general relationship between ER and sediment discharge covering all treatments studied predicted ER values very similar to those measured in field studies and those predicted by a general relationship derived from field studies.

Experimental Zoogeography: Colonization of Marine Mini-Islands

Plastic mesh sponges, considered to be islands for a variety of marine invertebrates, are used to explore island colonization in the marine environment. Colonization of small and large sponges, simultaneously submerged either near or far from an algal bed thought to be a potential source of colonists, is compared with expectations derived from the MacArthur-Wilson equilibrium model of island colonization. Conclusions in this study are based on colonists from five phyla comprising approximately 220 species and 26,000 individuals. Inspection of colonization curves (species present vs. time) for several sponge series indicates to varying degrees a stabilization of species numbers over time when time is plotted linearly. This impression is confirmed statistically by showing that a significant decrease in slope occurs in the later portion of the colonization curve. This supports the equilibrium concept of the MacArthur-Wilson model. Data from an identical, but much shorter, set of experiments begun during a sl...