Morphological profiling in human neural progenitor cells classifies hits in a pilot drug screen for Alzheimer's disease

Alzheimer's disease accounts for 60-70% of dementia cases. Current treatments are inadequate and there is a need to develop new approaches to drug discovery. Recently, in cancer, morphological profiling has been used in combination with high-throughput screening of small-molecule libraries in human cells in vitro. To test feasibility of this approach for Alzheimer's disease, we developed a cell morphology-based drug screen centred on the risk gene, SORL1 (which encodes the protein SORLA). Increased Alzheimer's disease risk has been repeatedly linked to variants in SORL1, particularly those conferring loss or decreased expression of SORLA, and lower SORL1 levels are observed in post-mortem brain samples from individuals with Alzheimer's disease. Consistent with its role in the endolysosomal pathway, SORL1 deletion is associated with enlarged endosomes in neural progenitor cells and neurons. We, therefore, hypothesized that multi-parametric, image-based cell phenotyping would identify features characteristic of SORL1 deletion. An automated morphological profiling method (Cell Painting) was adapted to neural progenitor cells and used to determine the phenotypic response of SORL1-/- neural progenitor cells to treatment with compounds from a small internationally approved drug library (TargetMol, 330 compounds). We detected distinct phenotypic signatures for SORL1-/- neural progenitor cells compared to isogenic wild-type controls. Furthermore, we identified 16 compounds (representing 14 drugs) that reversed the mutant morphological signatures in neural progenitor cells derived from three SORL1-/- induced pluripotent stem cell sub-clones. Network pharmacology analysis revealed the 16 compounds belonged to five mechanistic groups: 20S proteasome, aldehyde dehydrogenase, topoisomerase I and II, and DNA synthesis inhibitors. Enrichment analysis identified DNA synthesis/damage/repair, proteases/proteasome and metabolism as key pathways/biological processes. Prediction of novel targets revealed enrichment in pathways associated with neural cell function and Alzheimer's disease. Overall, this work suggests that (i) a quantitative phenotypic metric can distinguish induced pluripotent stem cell-derived SORL1-/- neural progenitor cells from isogenic wild-type controls and (ii) phenotypic screening combined with multi-parametric high-content image analysis is a viable option for drug repurposing and discovery in this human neural cell model of Alzheimer's disease.

A cautionary note on the use of N-acetylcysteine as a reactive oxygen species antagonist to assess copper mediated cell death

A new form of cell death has recently been proposed involving copper-induced cell death, termed cuproptosis. This new form of cell death has been widely studied in relation to a novel class of copper ionophores, including elesclomol and disulfiram. However, the exact mechanism leading to cell death remains contentious. The oldest and most widely accepted biological mechanism is that the accumulated intracellular copper leads to excessive build-up of reactive oxygen species and that this is what ultimately leads to cell death. Most of this evidence is largely based on studies using N-acetylcysteine (NAC), an antioxidant, to relieve the oxidative stress and prevent cell death. However, here we have demonstrated using inductively coupled mass-spectrometry, that NAC pretreatment significantly reduces intracellular copper uptake triggered by the ionophores, elesclomol and disulfiram, suggesting that reduction in copper uptake, rather than the antioxidant activity of NAC, is responsible for the diminished cell death. We present further data showing that key mediators of reactive oxygen species are not upregulated in response to elesclomol treatment, and further that sensitivity of cancer cell lines to reactive oxygen species does not correlate with sensitivity to these copper ionophores. Our findings are in line with several recent studies proposing the mechanism of cuproptosis is instead via copper mediated aggregation of proteins, resulting in proteotoxic stress leading to cell death. Overall, it is vital to disseminate this key piece of information regarding NAC's activity on copper uptake since new research attributing the effect of NAC on copper ionophore activity to quenching of reactive oxygen species is being published regularly and our studies suggest their conclusions may be misleading.

Perceived Exertion During Incremental Cycling is not Influenced by the Type A Behavior Pattern

Recent publications have perpetuated a concern that the Type A Behavior Pattern (TABP) influences ratings of perceived exertion (RPE) during exercise testing. Previous studies of this topic used the Jenkins Activity Survey (JAS) which lacks validity for predicting the criterion Structured Interview (SI) for TABP and used exercise protocols that were unstandardized or yielded results that were uninterpretable for clinical exercise prescription. We used the SI to classify 44 normotensive men (18-35 y) according to TABP and compared their RPE during an incremental cycling test to peak oxygen uptake (VO2peak). Groups did not differ on maximal test performance or RPE at any stage of the test, even after adjusting RPE for small group variations in % VO2peak and ventilatory equivalent for oxygen, which are strong correlates of RPE during incremental exercise. The findings agree with our prior report [14] that no relationship existed between RPE and several self-report measures of TABP. We conclude that there is no empirical basis for the view that the Type A Behavior Pattern affects cycling performance or ratings of perceived exertion during standard exercise testing in young white men.

Bradycardia during baroreflex stimulation and active or passive stressor tasks: cardiorespiratory fitness and hostility

We examined whether the resting bradycardia associated with cardiorespiratory fitness extends to lowered heart rate (HR) and mean arterial pressure during novel passive or active laboratory stressors and to a longer heart period during stimulation of the carotid-cardiac vagal baroreflex, independently of the Type A behavior pattern (TABP) and hostility. Forty-four normotensive Caucasian men (18-35 years of age) completed the Structured Interview for TABP, the Cook-Medley Hostility Scale, and a peak oxygen uptake (Vo2peak) test. Vo2peak was inversely related to HR prior to, during, and after each stressor and was positively related to heart period during baroreflex testing. Hostility was inversely related to heart period during baroreflex testing. TABP had no effects. Our findings indicate that cardiorespiratory fitness and low hostility are independently associated with a bradycardia during stimulation of the carotid-cardiac baroreflex, consistent with a possible enhancement of cardiac vagal tone.

Absence of enhanced sympathoadrenal activity and behaviorally evoked cardiovascular reactivity among offspring of hypertensives

To determine whether offspring of hypertensives show enhanced sympathetic nervous system activity, we evaluated several indices of sympathoadrenal activation and cardiovascular responsiveness to behavioral stimuli among 90 normotensive, young adult men having either one or two hypertensive parents (PH+(-), PH++) or normotensive parents only (PH--) (n = 30/group). Measurements included heart rate (HR) and blood pressure (BP) reactions to three mental stressors (the Stroop test, mental arithmetic, mirror tracing), a cold pressor test, postural adjustment (60 degrees upright tilt), isometric exercise and bicycle ergometry, as well as the 24-h excretion of catecholamines (epinephrine [E], norepinephrine [NE]) and venous plasma catecholamine concentrations, both at rest (seated and supine) and in response to the Stroop test and upright tilt. The three groups did not differ in age, education, body mass index (BMI), estimated aerobic fitness, resting HR, cardiac preejection period (PEP) and PEP:LVET (left ventricular ejection time) ratio, 24-h Na or K excretion, or fasting lipids, insulin or plasma renin activity. Resting systolic and diastolic BP varied as a function of parental hypertension, and were significantly higher in PH++ than among PH-- subjects (P < .05). No significant group difference was observed on any measure of plasma or urinary catecholamines, nor did offspring of hypertensives (PH++ or PH+-) showed greater HR or BP reactions than PH-- subjects to any of the several laboratory challenges. In sum, we find no evidence of enhanced sympathetic activity or heightened cardiovascular responsiveness among normotensive young adults who are familially predisposed to essential hypertension.

Breathlessness predicts perceived exertion in young women with mild asthma

We examined ratings of breathlessness (BRE) as a predictor of perceived exertion (RPE) during incremental cycling at power outputs of 50, 75, and 100 W. Young females (21 yr +/- 1.9) diagnosed with mild asthma (N = 25) were compared with females having normal lung function (N = 25) matched for age, VO2peak, trait anxiety, activity history (7-d recall), and BMI (kg.m-2). Relative oxygen consumption (%VO2peak), blood lactate concentration, VE.VO2(-1), and state anxiety were statistically controlled in hierarchical multiple linear regression analyses. For each group, %VO2peak explained 60% of the variance in RPE across power outputs (P less than 0.001); R2 was unchanged (P greater than 0.10) with the addition of blood lactate, VE.VO2(-1), and state anxiety. Absolute RPE and BRE did not differ between groups at any power output, but partial standardized (beta) and unstandardized (b) regression coefficients and increases in R2 showed that BRE had a greater effect (P less than 0.01) on RPE for asthmatics [adjusted R2 increased to 0.89; (beta) = 0.75; (b) = 0.79 +/- 0.06] than for controls [adjusted R2 increased to 0.74; (beta) = 0.52; (b) = 0.51 +/- 0.09]. The standard error of the prediction was 0.79 for asthmatics and 1.16 for controls. The prediction of RPE by BRE was not moderated by variation in forced expiratory volume for 1 s (FEV1), forced vital capacity (FVC) or peak inspiratory flow (VI). Physiological responses were similar for the groups, but blood lactate was higher in asthmatics at rest, at each power output, and at VO2peak.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of regular voluntary exercise on resting cardiovascular responses in SHR and WKY pregnant rats

The purpose of this study was to assess the influence of regular voluntary exercise in pregnant normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats on 1) uteroplacental perfusion and mean arterial pressure in the resting conscious condition and 2) fetal number, fetal weight, and number of fetal resorptions. WKYs and SHRs were randomly assigned to standard cages [CWKY (n = 10); CSHR (n = 6)] or cages with activity wheels [EWKY (n = 7); ESHR (n = 8)]. EWKYs and ESHRs exercised for 12 wk, and then all rats were bred and experiments were conducted on gestational day 17. Resting blood flow (microspheres), heart rate (HR), and mean arterial pressure (Pa) were measured. No significant difference was found in Pa, HR, uterine blood flow (ESHRs 52 +/- 8 ml.min-1.100 g-1; CSHRs 28 +/- 6 ml.min-1.100 g-1), or maternal placental blood flow (ESHRs, 122 +/- 31 ml.min-1.100 g-1; CSHRs 78 +/- 21 ml.min-1.100 g-1) among the groups. Exercise altered the relationship between maternal placental and uterine blood flow and Pa in the SHR; SHRs with lower Pa maintained higher placental and uterine blood flow after training. Before gestation ESHRs ran on average more kilometers per week than EWKYs (43 +/- 3 vs. 34 +/- 4), but during gestation ESHRs averaged fewer kilometers per week than EWKYs (16 +/- 4 vs. 22 +/- 4). Succinate dehydrogenase activity was higher in the white vastus lateralis (1.02 +/- 0.2 mumol cytochrome c reduced.min-1.g wet wt-1) and vastus intermedius (3.1 +/- 0.5 mumol cytochrome c reduced.min-1.g wet wt-1) muscles of ESHRs.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of dietary carbohydrate on RPE at the lactate and ventilatory thresholds

This study used manipulation of dietary intake and substrate utilization to dissociate the ventilatory (TVE) and lactate (TLAC) thresholds, and investigated the role of the thresholds in perception of effort as measured by the Borg 15-category rating of perceived exertion (RPE) scale. Thirteen males performed graded exercise tests following: a) glycogen depletion (GD) and 3 d on a high-carbohydrate diet (HC, 93% total daily energy intake as carbohydrate), b) GD and 3 d on a low-carbohydrate diet (LC, 21%), and c) a mixed-carbohydrate diet (NC, 51%). During submaximal exercise at intensities between 30 and 90% of peak oxygen uptake (VO2peak), significant differences among conditions (P less than 0.05) were obtained for carbon dioxide elimination, respiratory exchange ratio, and plasma lactate, with HC greater than NC greater than LC. Mean (+/- SD) TLAC occurred at different (P less than 0.05) percentages of VO2peak, with HC (55.6 +/- 2.9%) less than NC (59.6 +/- 2.9%) less than LC (63.8 +/- 2.8%). Means for TVE were not different. RPE at TLAC were significantly different (P less than 0.01) among conditions, with HC (12.6 +/- 0.6) less than NC (13.8 +/- 0.6) less than LC (14.3 +/- 0.7), but RPE at TVE were not different. It was concluded that the perception of exertion as becoming "somewhat hard" to "hard" is more closely linked to TVE than to TLAC.

Estimates of Type A behavior do not predict perceived exertion during graded exercise

Earlier studies have concluded that exercise tolerance during graded stress testing is overestimated in males showing the Type A Behavior Pattern (TABP) because of high motivation and suppressed ratings of perceived exertion (RPE). However, the studies used the Jenkins Activity Survey (JAS) to assess TABP and employed exercise protocols that were unstandardized or uninterpretable for clinical prescription. Because the JAS lacks validity for predicting the criterion Structured Interview (SI) for TABP, the usefulness of concurrent self-report estimates of TABP for predicting RPE during standard exercise testing warrants additional study. During clinical treadmill testing of 86 asymptomatic Caucasian men (45 +/- 9 yr), we examined three standard estimates of TABP (JAS, Bortner, Framingham) as predictors of: 1) the covariance (RPE') of RPE (Borg Category Scale) with VO2 (ml.kg-1.min-1) during 5 min of graded walking (5.47 km.h-1, 2.25%.min-1); 2) VO2 and RPE (11.6 +/- 2.2) at a preferred level of exertion (approximately 65% +/- 10% VO2PEAK); 3) VO2PEAK and RPE at VO2PEAK. Multiple linear regression analyses found no relations (P greater than 0.10) between estimates of TABP and treadmill responses. Discriminant analyses of Type A and Type B groups formed from tertiles consistent with population norms showed no differences (P greater than 0.01) for RPE of treadmill performance. Our findings question prior reports of RPE suppression associated with TABP estimates. We conclude that practically implementable estimates of TABP do not offer useful information for clinical predictions of RPE, preferred exertion level, or VO2PEAK in asymptomatic middle-aged Caucasian men.

Prediction of oxygen uptake on a bicycle wind-loaded simulator

The primary purpose of this study was to determine the accuracy of estimating oxygen uptake (VO2) from the flywheel revolution rate of a bicycle wind-loaded simulator. VO2 at four different flywheel revolution rates was measured on a Findlay Road Machine (FRM). Ten male trained cyclists, 10 male untrained cyclists, 10 female trained cyclists and 10 female untrained cyclists served as subjects. Significant curvilinear relationships (P less than 0.01) were found between road speed estimated from flywheel revolution rate and VO2 expressed as 1.min-1, ml.kg-1.min-1, 1.min-1.m-2 (r = 0.97, 0.96, 0.98, respectively). The absolute standard error of the mean VO2 was 0.21 l.min-1 (9.6%), 3.71 ml.kg-1.min-1 (11.5%) and 0.10 l.min-1.m-2 (7.9%), respectively. The relationship between VO2 and speed was similar to that reported during road cycling. To determine the magnitude of between-machine differences in VO2, six subjects randomly performed cycling using two different FMR. Significant (P less than 0.05) differences between machines were found at only the highest speed. The present study indicates that it is possible to accurately predict VO2 from flywheel revolution rate using a FRM. Since the FRM appears to approximate the resistance a cyclist experiences on the road and allows cyclists to use their own bicycle, it provides a good alternative to traditional laboratory ergometers.

Is the gender difference in peak VO2 greater for arm than leg exercise?

Based on observations that the difference between men and women in estimates of arm musculature is greater than the difference in leg musculature, it was hypothesized that the gender difference in peak oxygen uptake (VO2; l.min-1) would be greater for arm exercise than leg exercise. To test this hypothesis, 19 (10 men, 9 women) highly trained swimmers (HT) and 20 (10 men, 10 women) untrained students (UT) were tested for peak VO2 on cycle and arm-crank ergometers. Arm and leg fat-free volumes (FFV) were measured to provide an estimate of muscle distribution. No gender difference was observed in either the arm-to-leg peak VO2 ratio (0.699 for the men vs 0.696 for the women) or in the arm-to-leg FFV ratio (0.410 for the men vs 0.402 for the women). Although the proportion of musculature in the arms as assessed by the FFV appeared to be the same in men and women, the similarity in muscle distribution was probably not responsible for the identical average arm-to-leg peak VO2 ratios. The variance in the muscle distribution accounted for only 2-4% of the variance in the arm-to-leg peak VO2 differences within individuals. We conclude that factors other than arm and leg muscle dimensions account for the variability in the arm-to-leg peak VO2 ratio and that the gender difference in peak VO2 is the same for arm and leg exercise.

Open-field behavior is not related to treadmill performance in exercising rats

We examined the association between open-field behavior and treadmill performance in 39 adult male Sprague-Dawley rats. Three daily, five-minute trials were conducted in an open field of 49 19 cm squares. The objectivity of the open-field test was established by intraclass correlations (R) for observer agreement on total squares traversed (R = .99) and a subjective behavioral rating scale for anxiety (R = .92). As expected, total squares were inversely correlated (r = -.86) with the subjective anxiety ratings. An independent observer also rated animals on treadmill performance across six daily, five-minute trials of level running at 15 m/min. Performance ratings were objective (rs = .89) and reproducible (R = .91). A volitional endurance run at 30 m/min on level grade was also conducted on a subsequent day. Extreme groups of low anxious (N = 7) and high anxious (N = 7) animals were then identified from convergent responses on total square traversals and the subjective behavioral ratings that were reproducible (R = .72 to .78) of trials two and three of the open-field test. Repeated measures ANOVA showed no group differences (p greater than 0.10) on mean treadmill performance across trials. Endurance was also the same for each group (p greater than 0.05). Our findings indicate that the open-field test is objective and reliable, and it does not reveal a selection bias effect on treadmill performance or endurance. Thus, open-field behavior can be used as a dependent or subject-matching variable in studies of adult male Sprague-Dawley rats when motor-driven treadmill running is a behavioral intervention or outcome measure.

High pressure liquid chromatographic assay for prednisone in bulk drug substances and tablets

A high pressure liquid chromatographic (HPLC) method was developed for the assay of prednisone in bulk drug substances and tablets. The sample was dissolved in water-methanol and an aliquot was analyzed by using HPLC. The average recovery of prednisone added to a prednisone tablet composite was 99.5% with a coefficient of variation of 1.07%. Prednisone was determined in 46 tablets (1-50 mg prednisone/tablet) formulated by 22 manufacturers, using the HPLC method and the USP blue tetrazolium assay. The results show that the HPLC method is more specific and faster than the USP method.

Separation and determination of testosterone and testosterone esters in selected pharmaceutical formulations

A rapid quantitative procedure is presented for the separation of testosterone esters from their hydrolysis products through the use of the acetonitrile-infusorial earth column. The method was applied to testosterone cypionate, testosterone enanthate, and testosterone propionate. Recovery and replication of reference standard testosterone and its three esters through the proposed method ranged from 99.1 to 100.3%, and the percent relative standard deviation ranged from 0.6 to 1.0%. Two samples can be separated into testosterone and testosterone ester fractions in about 1.5 hr. The analyses of 20 injectable and one buccal tablet formulations made by 12 different manufacturers are reported.

Kinetic and mechanistic studies of blue tetrazolium reaction with phenylhydrazines

The reaction kinetics of blue tetrazolium with selected arylhydrazines were investigated under pseudo-first-order conditions. The reaction rate constants were obtained at various temperatures, and the enthalpy (8.4-11.2 kcal/mole) and entropy (-38--45 eu) of activations were calculated. A Hammett plot yielded a straight line with a slope of 0.52. The reaction was inhibited by atmospheric oxygen and iodine. A free radical mechanism is presented.

Rapid blue tetrazolium procedure for analysis of corticosteroids in pharmaceutical preparations

A rapid quantitative analysis of nine selected corticosteroids and corticosteroid esters at room temperature is described. The procedure is similar to the official blue tetrazolium reaction for corticosteroids, except that methylene chloride instead of alcohol USP is used as a solvent and the reagents are dissolved in or diluted with nonaqueous solvents. These two modifications reduce the medium polarity, which increases the reaction rate. The reactions are complete in 7-18 min, and the formazans are stable for at least 90 min. The results from 15 different pharmaceutical formulations, 12 containing hydrocortisone and three containing prednisolone acetate, show that the proposed method gives results that compare favorably with those obtained by the official blue tetrazolium, isoniazid, and phenylhydrazine procedures.

Analysis of betamethasone and its organic esters in pharmaceutical products

A rapid, quantitative analysis for betamethasone and its organic esters at room temperature is described. The method is similar to the official blue tetrazolium reaction for corticosteroids, except that methylene chloride is used as the solvent. The reaction is complete in 27-69 min, and the formazans produced are stable for at least 90 min after the addition of tetramethylammonium hydroxide. The results of the analysis of 13 different pharmaceutical formulations by the proposed method are reported. The degradation of betamethasone and its esters caused by strong bases is a pseudo-first-order reaction in methylene chloride. The average half-life of the corticosteroids studied is 56 min under the basic conditions described.

Kinetics and mechanism of blue tetrazolium reaction with corticosteroids

The kinetics of the reaction of blue tetrazolium with corticosteroids were investigated under pseudo-first-order conditions. The reaction rates for various corticosteroids were determined at various temperatures, and the enthalpy and entropy of activation for these compounds were determined. A mechanism is proposed in which an electron pair and a proton are transferred to blue tetrazolium from the anion formed by the action of tetramethylammonium hydroxide on the alpha-carbonyl moiety of the corticosteroid. The proposed mechanism is consistent with previous experimental results.

Effect of solvent on tetrazolium reaction

The rate of color development of a tetrazolium formazan is shown to be inversely proportional to the dielectric constant of the solvent medium and directly proportional to the hydrogen-bonding capability of solvent mixtures having the same dielectric constant. The geometric isomers of the formazans have different absorbance maxima, and the wavelength of maximum absorbance of a mixture of formazans in different solvents depends upon which isomer predominates in that solvent. The trans-syn-isomer (blue form) of blue tetrazolium has a maximum absorbance at 625 nm in dimethylformamide while the trans-anti-isomer (red form) absorbs at 517 nm in methanol. The absorbance maxima of the corresponding isomers of the formazans of triphenyltetrazolium occur at 535 and 485 nm, respectively. Water and/or methanol (to a lesser extent) are important in the stabilization of the trans-anti-isomer, since the small size of these two substances allows them to form strong intermolecular hydrogen bonds with one or both nitrogen atoms of the azo linkage, thereby preventing the formation of the intramolecular hydrogen bonding exhibited by the trans-syn-isomer. The formazan produced by the reaction of corticosteroids with tetrazolium in strongly basic media can lose a reduction unit and be reoxidized to the tetrazolium. This reaction is solvent dependent and occurs at a much faster rate in chloroform than in alcohol USP.

Determination of iodochlorhydroxyquin and corticosteroids in pharmaceutical formulations

Iodochlorhydroxyquin was separated from various corticosteroids using an acetonitrile-diatomaceous earth column. Iodochlorhydroxyquin was eluted with cyclohexane, and the corticosteroid was eluted with chloroform. Iodochlorhydroxyquin was determined by both a UV absorbance method and a new compleximetric method using the nickel chelate of iodochlorhydroxyquin. The corticosteroid was determined by the blue tetrazolium and isoniazid procedures. The average percent recovery for these four methods was 100.8, 99.4,100.7, and 99.9, respectively, for 10 known mixtures. The standard deviation for the absorbance for 10 determinations of the nickel complex was 0.002 absorbance unit (0.31%). Various characteristics of the nickel and other complexes were evaluated, including the sensitivity, solubility, and wavelength of maximum absorbance in 14 different solvents. The analyses of 23 typical products are reported, for which the standard deviation, expressed as a percentage of the amount declared, was 1.31% for the UV, 1.34% for the compleximetric, 1.49% for the blue tetrazolium, and 1.22% for the isoniazid procedures. Methods of determination in the presence of interferences are discussed.

Reduction of blue tetrazolium by corticosteroids

Pseudo-first-order rate constants were observed for the reaction of corticosteroid or corticosteroid esters with blue tetrazolium. The data indicate that the reactivity of corticosteroids is, in part, a function of their geometry in that corticosteroid reactivity toward blue tetrazolium increases with increasing planarity of the steroid molecule and that corticosteroid esters must be hydrolyzed as a necessary prerequisite to reaction with blue tetrazolium. Evidence is presented indicating that free radicals are not involved in the blue tetrazoliun reaction with corticosteroids. Certain pharmaceutically important compounds such as pyrocatechol derivatives and hydroquinone appear to reduce blue tetrazolium by the anion free radical mechanism proposed previously. A spectrophotometric method for determining the number of reduction units transferred to blue tetrazolium per molecule is described.