Daniel S. Strasser

Genetic screening for Niemann-Pick disease type C in adults with neurological and psychiatric symptoms: findings from the ZOOM study.

Niemann–Pick disease type C (NP-C) is a rare, autosomal-recessive, progressive neurological disease caused by mutations in either the NPC1 gene (in 95% of cases) or the NPC2 gene. This observational, multicentre genetic screening study evaluated the frequency and phenotypes of NP-C in consecutive adult patients with neurological and psychiatric symptoms. Diagnostic testing for NP-C involved NPC1 and NPC2 exonic gene sequencing and gene dosage analysis. When available, results of filipin staining, plasma cholestane-3β,5α,6β-triol assays and measurements of relevant sphingolipids were also collected. NPC1 and NPC2 gene sequencing was completed in 250/256 patients from 30 psychiatric and neurological reference centres across the EU and USA [median (range) age 38 (18–90) years]. Three patients had a confirmed diagnosis of NP-C; two based on gene sequencing alone (two known causal disease alleles) and one based on gene sequencing and positive filipin staining. A further 12 patients displayed either single mutant NP-C alleles (8 with NPC1 mutations and 3 with NPC2 mutations) or a known causal disease mutation and an unclassified NPC1 allele variant (1 patient). Notably, high plasma cholestane-3β,5α,6β-triol levels were observed for all NP-C cases (n = 3). Overall, the frequency of NP-C patients in this study [1.2% (95% CI; 0.3%, 3.5%)] suggests that there may be an underdiagnosed pool of NP-C patients among adults who share common neurological and psychiatric symptoms.

Differential Effects of the Dual Orexin Receptor Antagonist Almorexant and the GABAA-α1 Receptor Modulator Zolpidem, Alone or Combined with Ethanol, on Motor Performance in the Rat

Current insomnia treatments such as γ-aminobutyric acid (GABA) receptor modulators are associated with sedative and muscle-relaxant effects, which increase when drug intake is combined with alcohol. This study compared the novel sleep-enabling compound almorexant (ACT-078573-hydrochloride), a dual orexin receptor antagonist, with the positive GABAA-α1 receptor modulator zolpidem. Both compounds were administered alone or in combination with ethanol, and their effects on forced motor performance were determined in Wistar rats upon waking after treatment. To detect substance-induced sedation and myorelaxation, time spent on an accelerating rotating rod (rotarod) and forepaw grip strength were measured. Zolpidem (10, 30, and 100 mg/kg, p.o.) and ethanol (0.32, 1, and 1.5 g/kg, i.p.) dose-dependently decreased rotarod performance and grip strength, whereas almorexant (30, 100, and 300 mg/kg, p.o.) did not. Doses of ethanol (0.32 and 1 g/kg), which were ineffective when administered alone, showed interactions with zolpidem (10 and 30 mg/kg) leading to reduced rotarod performance and grip strength; in contrast, combination of ethanol (0.32 and 1 g/kg) with almorexant (100 and 300 mg/kg) did not reduce performance or grip strength below ethanol alone. We conclude that unlike zolpidem, almorexant does not interfere with forced motor performance or grip strength in the rat, nor does it further increase the sedative effects of ethanol. Our results suggest that the effect of almorexant can be immediately reversed to full alertness like under physiological sleep, and that almorexant is less likely to show strong sedation, excessive myorelaxation, or interaction with alcohol than commonly prescribed hypnotics such as zolpidem.

Structure-guided design, synthesis and biological evaluation of novel DNA ligase inhibitors with in vitro and in vivo anti-staphylococcal activity.

A series of 2-amino-[1,8]-naphthyridine-3-carboxamides (ANCs) with potent inhibition of bacterial NAD(+)-dependent DNA ligases (LigAs) evolved from a 2,4-diaminopteridine derivative discovered by HTS. The design was guided by several highly resolved X-ray structures of our inhibitors in complex with either Streptococcus pneumoniae or Escherichia coli LigA. The structure-activity-relationship based on the ANC scaffold is discussed. The in-depth characterization of 2-amino-6-bromo-7-(trifluoromethyl)-[1,8]-naphthyridine-3-carboxamide, which displayed promising in vitro (MIC Staphylococcus aureus 1 mg/L) and in vivo anti-staphylococcal activity, is presented.

Examining the role of endogenous orexins in hypothalamus-pituitary-adrenal axis endocrine function using transient dual orexin receptor antagonism in the rat.

The orexin neuropeptide system regulates wakefulness and contributes to physiological and behavioral stress responses. Moreover, a role for orexins in modulating hypothalamus-pituitary-adrenal (HPA) axis activity has been proposed. Brain penetrating dual orexin receptor (OXR) antagonists such as almorexant decrease vigilance and have emerged as a novel therapeutic class for the treatment of insomnia. Almorexant was used here as a pharmacological tool to examine the role of endogenous orexin signaling in HPA axis endocrine function under natural conditions. After confirming the expression of prepro-orexin and OXR-1 and OXR-2 mRNA in hypothalamus, pituitary and adrenal glands, the effects of systemic almorexant were investigated on peripheral HPA axis hormone release in the rat under baseline, stress and pharmacological challenge conditions. Almorexant did not alter basal or stress-induced corticosterone release despite affecting wake and sleep stages (detected by radiotelemetric electroencephalography/electromyography) during the stress exposure. Moreover, almorexant did not affect the release of adrenocorticotropin (ACTH) and corticosterone at different time points along the diurnal rhythm, nor corticotrophin-releasing hormone (CRH)- and ACTH-stimulated neuroendocrine responses, measured in vivo under stress-free conditions. These results illustrate that dual OXR antagonists, despite modulating stress-induced wakefulness, do not interfere with endocrine HPA axis function in the rat. They converge to suggest that endogenous orexin signaling plays a minor role in stress hormone release under basal conditions and under challenge.

Serum IL-5 and IL-13 consistently serve as the best predictors for the blood eosinophilia phenotype in adult asthmatics

Molecular biomarkers that identify the phenotype of blood eosinophilia were evaluated in adult asthmatics, and their relationship with clinically significant asthma outcomes was assessed. Patients were clustered based on their molecular fingerprint.

Identification of Cathepsin L as a Potential Sex-Specific Biomarker for Renal Damage

The renin-angiotensin system is a well-known regulator of blood pressure and plays an important role in the pathogenesis of cardiovascular disease and renal damage. Genetic factors, including single nucleotide polymorphisms and sex, are increasingly recognized as potential risk factors for the development of cardiovascular disease. Double transgenic rats (dTGRs), harboring human renin and angiotensinogen genes, were used in this study to investigate potential sex differences influencing renal function and renal gene expression. dTGR males and females had comparable increases in blood pressure, whereas body weight, albuminuria/proteinuria, and urine flow rate were higher in males. At 8 weeks of age, renal plasma flow and glomerular filtration rate were proportionally lower in males, and renal vascular resistance tended to be higher. Males developed more severe tubulointerstitial and vascular lesions. By the end of week 8, 40%of the males but none of the females had died. Genome expression studies were performed with RNA from kidneys of 7-week–old male and female dTGRs and control rats to further investigate the sex-related differences on a molecular level. Forty-five genes showed sex-dependent expression patterns in dTGRs that were significantly different compared to controls. Cathepsin L, one of the genes differentially expressed between the sexes, was also shown to be strongly associated with the degree of renal injury. In dTGRs, urinary cathepsin L at week 7 was higher in males (nanograms per 24 hours: male, 512±163; female, 132±70). These results reveal a potential new biomarker for the personalized diagnosis and management of chronic kidney disease.

A novel CRTH2 antagonist: Single- and multiple-dose tolerability, pharmacokinetics, and pharmacodynamics of ACT-453859 in healthy subjects.

The chemoattractant receptor‐homologous molecule expressed on T‐helper 2 cells (CRTH2) is a G‐protein‐coupled receptor for prostaglandin D2, a key mediator in inflammatory disorders. In this randomized, double‐blind, placebo‐controlled study we investigated the single‐ and multiple‐dose tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) up to a dose of 800 mg once a day of ACT‐453859, a potent and selective CRTH2 antagonist. ACT‐453859 was moderately rapidly absorbed and followed a biphasic elimination pattern, with an elimination half‐life between 11 and 20 hours. Steady‐state conditions were reached after 1 day, and ACT‐453859 did not accumulate. Urinary excretion of unchanged ACT‐453859 did not exceed 1.4% of the administered dose. Administration of ACT‐453859 resulted in a dose‐dependent blockadeof CRTH2 on the surface of eosinophils. The maximum PD effect of ACT‐453859 was reached about 2.0 hours after dosing, which corresponded to the highest concentration at which PD were assessed. At steady state, 100 and 800 mg ACT‐453859 once a day resulted in blockade of CRTH2 over 24 hours. In this entry‐into‐humans study, ACT‐453859 showed good tolerability at all doses and a PK and PD profile compatible with once‐daily dosing.

Sex comparison on long-lasting behavioral and physiological disturbances induced by single shock experience in rats.

Enhanced female vulnerability and symptom severity are described in post-traumatic stress disorder (PTSD). It remains largely unknown whether females present with more pronounced PTSD-like symptoms than males in rodent models of PTSD. A model of single electric foot-shock followed by situational reminders was used to investigate in rats the impact of sex on potential long-lasting changes in anxiety-like behavior, and in endocrine and physiological responses to stress and fearful situations. Three weeks after single shock exposure (in the dark side of a shuttle box) both male and female rats spent less time in the dark compartment of a dark-light box and in the closed arms of an elevated plus maze than non-shocked controls. Both behaviors were likely due to avoidance of places reminiscent of the initial shock context. The shock exposure had no long-term impact on social interaction behavior or on basal and restraint stress-induced increases in plasma corticosterone. Shock exposure increased sudden silence-induced freezing responses and hyperthermia during novelty stress and fear to a similar extent in both males and females and left heart rate responses unaffected. Non-shocked females generally showed a reduced response or faster recovery to baseline under stress- or fearful test conditions as compared to non-shocked males, which was likely due to differential sex-specific coping strategies. Taken together, our results suggest that, despite some baseline sex differences, both male and female rats are similarly affected in the long-term by the initial foot-shock exposure used in this particular simulation of PTSD.

Endothelin ET A Receptor Blockade, by Activating ET B Receptors, Increases Vascular Permeability and Induces Exaggerated Fluid Retention

Endothelin (ET) receptor antagonists have been associated with fluid retention. It has been suggested that, of the two endothelin receptor subtypes, ETB receptors should not be blocked, because of their involvement in natriuresis and diuresis. Surprisingly, clinical data suggest that ETA-selective antagonists pose a greater risk of fluid overload than dual antagonists. The purpose of this study was to evaluate the contribution of each endothelin receptor to fluid retention and vascular permeability in rats. Sitaxentan and ambrisentan as ETA-selective antagonists and bosentan and macitentan as dual antagonists were used as representatives of each class, respectively. ETA-selective antagonism caused a dose-dependent hematocrit/hemoglobin decrease that was prevented by ETB-selective receptor antagonism. ETA-selective antagonism led to a significant blood pressure reduction, plasma volume expansion, and a greater increase in vascular permeability than dual antagonism. Isolated vessel experiments showed that ETA-selective antagonism increased vascular permeability via ETB receptor overstimulation. Acutely, ETA-selective but not dual antagonism activated sympathetic activity and increased plasma arginine vasopressin and aldosterone concentrations. The hematocrit/hemoglobin decrease induced by ETA-selective antagonism was reduced in Brattleboro rats and in Wistar rats treated with an arginine vasopressin receptor antagonist. Finally, the decrease in hematocrit/hemoglobin was larger in the venous than in the arterial side, suggesting fluid redistribution. In conclusion, by activating ETB receptors, endothelin receptor antagonists (particularly ETA-selective antagonists) favor edema formation by causing: 1) fluid retention resulting from arginine vasopressin and aldosterone activation secondary to vasodilation, and 2) increased vascular permeability. Plasma volume redistribution may explain the clinical observation of a hematocrit/hemoglobin decrease even in the absence of signs of fluid retention.

Eosinophilic oesophagitis: relevance of mast cell infiltration

Eosinophilic oesophagitis (EoE) is a chronic inflammatory disease characterised clinically by symptoms of oesophageal dysfunction and histopathologically by a prominent eosinophilic inflammation. Despite eosinophils having a histologically predominant position, their role in the immunopathogenesis of the disease is still questionable. Several other inflammatory cells are involved and may also play a critical role. The purpose of this study was to characterise the mast cell infiltration, and to correlate it with the clinical state of EoE.