Symmetrical drug-related intertriginous and flexural exanthema/baboon syndrome induced by traditional Chinese medicine.

BACKGROUND: Symmetrical drug-related intertriginous and flexural exanthema (SDRIFE) refers to an uncommon cutaneous adverse reaction that symmetrically involves the buttock and intertriginous areas after systemic exposure to the offending drug and is previously known as baboon syndrome. SDRIFE related with traditional Chinese medicine (TCM) has not been reported. OBJECTIVE: We presented a case of SDRIFE /baboon syndrome induced by TCM, Xi-Huang capsule. METHODS: A 57-years-old man presented with macular erythematous rash mainly on his intergluteal, inguinal, axillary, popliteal regions for a duration of 5 days. The lesions appeared a day after an oral Chinese patent medicine Xi-Huang capsule for arthralgia. Drug eruption was diagnosed. The rash disappeared completely within a week with immediate discontinuation of Xi-Huang capsule and a short term of systemic therapy with glucocorticosteroids. Patch testing was performed on the patient 1 month after complete resolution. He was patch tested with Xi-Huang capsule (5% and 10% in petroleum) using Finn Chambers on Scanpor tape and T.R.U.E. test system. Five heathy volunteers were also patch tested with the same Xi-Huang capsule. RESULTS: Patch testing to 20 common contact allergens including nickel and fragrance were negative. TCM patch test was positive. No positive results were found in five volunteers. Months later, the patient relapsed after an oral herbal Chinese medicine challenge for arthralgia. To avoid the rash recurrence, he stopped taking any Chinese herbal medicine and had complete resolution of disease. CONCLUSION: The Chinese patent drugs for external and oral have unique advantages and have been widely used in many diseases. It is important that dermatologists monitor for clinically significant manifestations of TCM, such as baboon syndrome. Patch testing could help make a definitive diagnosis.

Hemochromatosis in Two Female Olive Baboons (Papio anubis).

This report describes hemochromatosis associated with chronic parenteral iron dextran administration in 2 female olive baboons (Papio anubis). These baboons were enrolled on an experimental protocol that induced and maintained anemia by periodic phlebotomy for use in studying potential treatments for sickle cell anemia. The 2 baboons both presented with clinical signs consistent with iron overload, including decreased appetite, weight loss, elevated liver enzymes, and hepatosplenomegaly. Histopathologic findings supported a morphologic diagnosis of systemic hemosiderosis, as evidenced by the overwhelming presence of iron in the reticuloendothelial system and liver after the application of Prussian blue stain. This finding, combined with the clinical presentation, lead to a final diagnosis of hemochromatosis. This case report suggests that providing anemic patients with chronic parenteral iron supplementation in the absence of iron deficiency can result in iatrogenic iron overload and subsequent systemic toxicity. Furthermore, these subjects may present with hemochromatosis and its associated clinical signs many years after cessation of iron supplementation.

In Vitro Screening of the Open-Source Medicines for Malaria Venture Malaria and Pathogen Boxes To Discover Novel Compounds with Activity against Balamuthia mandrillaris.

Balamuthia mandrillaris is an under-reported, pathogenic free-living amoeba that causes Balamuthia amoebic encephalitis (BAE) and cutaneous skin infections. Although cutaneous infections are not typically lethal, BAE with or without cutaneous involvement is usually fatal. This is due to the lack of drugs that are both efficacious and can cross the blood-brain barrier. We aimed to discover new leads for drug discovery by screening the open-source Medicines for Malaria Venture (MMV) Malaria Box and MMV Pathogen Box, with 800 compounds total. From an initial single point screen at 1 and 10 µM, we identified 54 hits that significantly inhibited the growth of B. mandrillarisin vitro Hits were reconfirmed in quantitative dose-response assays and 23 compounds (42.6%) were confirmed with activity greater than miltefosine, the current standard of care.

Costs and drivers of helminth parasite infection in wild female baboons.

Helminth parasites can have wide-ranging, detrimental effects on host reproduction and survival. These effects are best documented in humans and domestic animals, while only a few studies in wild mammals have identified both the forces that drive helminth infection risk and their costs to individual fitness. Working in a well-studied population of wild baboons (Papio cynocephalus) in the Amboseli ecosystem in Kenya, we pursued two goals, to (a) examine the costs of helminth infections in terms of female fertility and glucocorticoid hormone levels and (b) test how processes operating at multiple scales-from individual hosts to social groups and the population at large-work together to predict variation in female infection risk. To accomplish these goals, we measured helminth parasite burdens in 745 faecal samples collected over 5 years from 122 female baboons. We combine these data with detailed observations of host environments, social behaviours, hormone levels and interbirth intervals (IBIs). We found that helminths are costly to female fertility: females infected with more diverse parasite communities (i.e., higher parasite richness) exhibited longer IBIs than females infected by fewer parasite taxa. We also found that females exhibiting high Trichuris trichiura egg counts also had high glucocorticoid levels. Female infection risk was best predicted by factors at the host, social group and population level: females facing the highest risk were old, socially isolated, living in dry conditions and infected with other helminths. Our results provide an unusually holistic understanding of the factors that contribute to inter-individual differences in parasite infection, and they contribute to just a handful of studies linking helminths to host fitness in wild mammals.

High Branched-Chain Amino Acid Concentrations Are Found in Preterm Baboons Receiving Intravenous Amino Acid Solutions and Mimic Alterations Found in Preterm Infants.

BACKGROUND: Parenteral amino acid (AA) nutrition administration after premature birth is necessary to ensure adequate growth and neurodevelopment. However, optimizing safety and efficacy remains a major challenge. This study investigated the effects of intravenous AA administration on plasma AA profiles in premature baboons and infants. METHODS: Premature baboons were delivered by cesarean section at 125 days (67% gestation) and chronically ventilated. At 24 hours of life, a parenteral AA protocol comparable to the early and high AA regimens used in premature infants was initiated. Serial plasma AA concentrations were obtained on days of life (DOLs) 1, 3, and 7 and compared with concentrations at similar DOLs from preterm infants. Fetal baboon (165 ± 2 days; 89% gestation) and term baboon plasma AA concentrations were obtained for comparison. RESULTS: Premature baboons receiving early and high parenteral AA supplementation exhibited significant differences in plasma AA concentrations compared with fetuses. In particular, concentrations of leucine, isoleucine, valine, and ornithine were elevated (fold increase: 2.14, 2.03, 1.95, and 16.5, respectively; P < 0.001) on DOL 3 vs fetuses. These alterations mimicked those found in preterm infants. CONCLUSION: Early and high AA supplementation in extremely premature baboons significantly disrupted plasma AA concentrations. Elevated concentrations of branched-chain AAs and ornithine raise concerns for adverse neurodevelopmental outcomes. These results are consistent with those found in premature human infants and emphasize the need to optimize parenteral AA solutions for the unique metabolic requirements of premature infants. Improved technologies for rapid monitoring of AA concentrations during treatment are essential.

Amino acid and lipid profiles following pig-to-primate liver xenotransplantation.

As outcomes in clinical liver transplantation steadily improve, demand continues to exceed supply, leading to a substantial disparity in organ availability. The translation of porcine liver xenotransplantation (LXT) into a clinical reality aims to address this dilemma. Our laboratory has previously established an applicable model of α-1,3-galactosyltransferase knockout (GalT-KO) pig-to-primate LXT with continuous human coagulation factor infusion and costimulation blockade. This report aims to further investigate the post-LXT lipid and amino acid metabolism profile in our longest surviving recipients (25 and 29 days). Experimental samples and control samples, consisting of pre-transplant porcine and baboon serum and plasma, were analyzed for standard lipid profiles and for amino acid levels. Lipid profiles of LXT recipients remained stable following xenotransplantation compared to donor porcine baseline levels. Amino acid concentrations also remained similar to baseline controls, with the exception of a 3-fold increase in l-ornithine and more than a 10-fold decrease in l-arginine post-transplant when compared to both porcine and baboon baseline levels. The observed changes in l-arginine are consistent with prior studies investigating the effects of graft preservation injury following liver transplantation. These results indicate that the porcine liver can maintain most biochemical profiles stably post-operatively in baboons and suggest that arginine supplementation post-LXT may potentially be useful for further prolongation of xenograft survival.

Comparison of vitamin D metabolites in wild and captive baboons.

Vitamin D adequacy is essential for multiple physiologic processes. With limited exposure to sunlight for vitamin D3 synthesis, captive primates are supplemented with vitamin D3 (cholecalciferol). Vitamin D metabolite data from wild primates living indigenously could suggest optimum levels. The purpose of this study was to: 1) to explore whether baboons, a speciose genus whose members have significant exposed skin, coat color variation and wide geographical distribution, mirrors the skin pigmentation-vitamin D relationship found in humans; 2) compare vitamin D metabolite levels in wild and captive members of the same or similar baboon species; and 3) apply a recently developed method currently used in humans for measuring multiple vitamin D metabolites as a panel to explore if/how these metabolites can inform us on vitamin D sufficiency. Serum samples from males of three baboon species in the wild: Papio anubis (olive baboon, dark exposed skin), P. cynocephalus (yellow baboon, brown exposed skin), and P. hamadryas (hamadryas baboon, pink exposed skin), were compared with vitamin D supplemented captive olive baboons with sun exposure. Liquid chromatography/tandem mass spectrometry (LC/MS/MS) measured vitamin D and its main metabolites. Cholecalciferol, 25 hydroxyvitamin D2&3 (25(OH)D2&3 ), and 24,25 dihydroxyvitamin D2&3 (24,25(OH)2 D2&3 ), showed significant differences by species. The levels of cholecalciferol due to supplements in the captive olive baboons did not convert to higher 25(OH)D3 while the wild olive baboons exhibited the lowest levels for both cholecalciferol and 25(OH)D3 . Further metabolic conversion of 25(OH)D3 to 24,25(OH)2 D3 indicated that all baboons had more similar conversion ratios and these were within the same range found for humans that are depicted as having adequate vitamin D levels. This study provided evidence that exposed skin color does influence vitamin D3 levels, with lower levels in darker skinned species, but these differences are eliminated in the downstream metabolite conversion indicating strong regulatory control.

Preclinical IV busulfan dose-finding study to induce reversible myeloablation in a non-human primate model.

In this study we utilized a large animal model to identify a dose of intravenous busulfan that can cause reversible myelosuppression. Nine baboons (Papio anubis) were treated with IV busulfan at 6.4 (Group A), 8 (Group B), or 9.6 mg/kg (Group C). Peripheral blood counts were measured up to 90 days after treatment and serial bone marrow samples were obtained to analyze CD34+ cell content and colony forming units. Overall, the highest grade of peripheral blood cytopenia was observed 15 days after treatment in all three groups (n = 3/group). In particular, we observed a notable reduction of neutrophil and platelet counts in the blood and the number of marrow CD34+ cells and colony forming units. In contrast, the effect of busulfan on hemoglobin levels was mild. Baboons who received the highest dose of busulfan showed only a 25-35% recovery of marrow CD34+ cells and colony forming units after 90 days of busulfan administration. However, all three groups of animals showed a full recovery of peripheral blood counts and normal marrow cellularity and tri-lineage hematopoiesis after treatment. Notably, all three doses of busulfan were tolerated well without significant extra-medullary toxicity. These results validate the hierarchy of blood cells likely targeted by busulfan, and based on these findings, clinical trials using myelotoxic but not myeloablative doses of intravenous busulfan will be designed for patients with myeloid malignancies.

Ceftriaxone Absorption Enhancement for Noninvasive Administration as an Alternative to Injectable Solutions.

Neonatal sepsis is a major cause of infant mortality in developing countries because of delayed injectable treatment, making it urgent to develop noninjectable formulations that can reduce treatment delays in resource-limited settings. Ceftriaxone, available only for injection, needs absorption enhancers to achieve adequate bioavailability via nonparenteral administration. This article presents all available data on the nonparenteral absorption of ceftriaxone in humans and animals, including unpublished work carried out by F. Hoffmann-La Roche (Roche) in the 1980s and new data from preclinical studies with rabbits, and discusses the importance of these data for the development of noninjectable formulations for noninvasive treatment. The combined results indicate that the rectal absorption of ceftriaxone is feasible and likely to lead to a bioavailable formulation that can reduce treatment delays in neonatal sepsis. A bile salt, chenodeoxycholate sodium salt (Na-CDC), used as an absorption enhancer at a 125-mg dose, together with a 500-mg dose of ceftriaxone provided 24% rectal absorption of ceftriaxone and a maximal plasma concentration of 21 µg/ml with good tolerance in human subjects. The rabbit model developed can also be used to screen for the bioavailability of other formulations before assessment in humans.

Oral administration of the LSD1 inhibitor ORY-3001 increases fetal hemoglobin in sickle cell mice and baboons.

Increased levels of fetal hemoglobin (HbF) lessen the severity of symptoms and increase the life span of patients with sickle cell disease (SCD). More effective strategies to increase HbF are needed because the current standard of care, hydroxyurea, is not effective in a significant proportion of patients. Treatment of the millions of patients projected worldwide would best be accomplished with an orally administered drug therapy that increased HbF. LSD1 is a component of corepressor complexes that repress γ-globin gene expression and are a therapeutic target for HbF reactivation. We have shown that subcutaneous administration of RN-1, a pharmacological LSD1 inhibitor, increased γ-globin expression in SCD mice and baboons, which are widely acknowledged as the best animal model in which to test the activity of HbF-inducing drugs. The objective of this investigation was to test the effect of oral administration of a new LSD1 inhibitor, ORY-3001. Oral administration of ORY-3001 to SCD mice (n = 3 groups) increased γ-globin expression, Fetal Hemoglobin (HbF)-containing (F) cells, and F reticulocytes (retics). In normal baboons (n = 7 experiments) treated with ORY-3001, increased F retics, γ-globin chain synthesis, and γ-globin mRNA were observed. Experiments in anemic baboons (n = 2) showed that ORY-3001 increased F retics (PA8695, predose = 24%, postdose = 66.8%; PA8698: predose = 13%, postdose = 93.6%), γ-globin chain synthesis (PA8695: predose = 0.07 γ/γ+ß, postdose = 0.20 γ/γ+ß; PA8698: predose = 0.02 γ/γ+ß, postdose = 0.44 γ/γ+ß), and γ-globin mRNA (PA8695: predose = 0.06 γ/γ+ß, postdose = 0.18 γ/γ+ß; PA8698: predose = 0.03 γ/γ+ß, postdose = 0.33 γ/γ+ß). We conclude that oral administration of ORY-3001 increases F retics, γ-globin chain synthesis, and γ-globin mRNA in baboons and SCD mice, supporting further efforts toward the development of this drug for SCD therapy.

A Manganese-based Alternative to Gadolinium: Contrast-enhanced MR Angiography, Excretion, Pharmacokinetics, and Metabolism.

Purpose To compare intravascular contrast enhancement produced by the manganese-based magnetic resonance (MR) imaging contrast agent manganese-N-picolyl-N,N',N'-trans-1,2-cyclohexenediaminetriacetate (Mn-PyC3A) to gadopentetate dimeglumine (Gd-DTPA) and to evaluate the excretion, pharmacokinetics, and metabolism of Mn-PyC3A. Materials and Methods Contrast material-enhanced MR angiography was performed in baboons (Papio anubis; n = 4) by using Mn-PyC3A and Gd-DTPA. Dynamic imaging was performed for 60 minutes following Mn-PyC3A injection to monitor distribution and elimination. Serial blood sampling was performed to quantify manganese and gadolinium plasma clearance by using inductively coupled plasma mass spectrometry and to characterize Mn-PyC3A metabolism by using high-performance liquid chromatography. Intravascular contrast enhancement in the abdominal aorta and brachiocephalic artery was quantified by measuring contrast-to-noise ratios (CNRs) versus muscle at 9 seconds following Mn-PyC3A or Gd-DTPA injection. Plasma pharmacokinetics were modeled with a biexponential function, and data were compared with a paired t test. Results Aorta versus muscle CNR (mean ± standard deviation) with Mn-PyC3A and Gd-DTPA was 476 ± 77 and 538 ± 120, respectively (P = .11). Brachiocephalic artery versus muscle CNR was 524 ± 55 versus 518 ± 140, respectively (P = .95). Mn-PyC3A was eliminated via renal and hepatobiliary excretion with similar pharmacokinetics to Gd-DTPA (area under the curve between 0 and 30 minutes, 20.2 ± 3.1 and 17.0 ± 2.4, respectively; P = .23). High-performance liquid chromatography revealed no evidence of Mn-PyC3A biotransformation. Conclusion Mn-PyC3A enables contrast-enhanced MR angiography with comparable contrast enhancement to gadolinium-based agents and may overcome concerns regarding gadolinium-associated toxicity and retention. © RSNA, 2017 Online supplemental material is available for this article.

Downregulation of miR­146a promotes proliferation and migration of AOB­treated embryoid body via PDGFRA induction.

Antioxidant of bamboo leaves (AOB) has been proven to have antioxidant activity and an inhibitory effect on free radicals that induce deterioration of macromolecules. The multi­target regulation of microRNAs (miRs) in the complicated process of vasculogenesis and angiogenesis lead to the use of miRNA therapy in vascular development. In the present study, the role of miRNAs on early embryo vascular development upon AOB stimulation was investigated. For this purpose, mouse embryonic stem cells were spontaneously differentiated as embryoid bodies (EBs) and were examined by phase contrast microscopy. miR­146a mimic and scramble control were transfected into EBs and potential targets of miR­146a were predicted. Cell proliferation and migration were detected by cell viability and wound­healing and migration assays, respectively. Angiogenesis was determined by the Spheroid sprouting assay. It was demonstrated that EBs transfected with miR­146a mimic had an increased growth rate compared with the control cells. miR­146a­transfected cells were very susceptible to AOB treatment. Furthermore, among the predicted miR­146a targets, platelet­derived growth factor receptor alpha (PDGFRA) was identified as a bona fide target of miR­146a. In conclusion, PDGFRA was demonstrated to participate in the modulation of cell migration and proliferation of mouse EBs. The present study expanded the current understanding of AOB biology and elucidated the mechanisms underlying early embryo vascular development upon AOB stimulation.

Soil eaten by chacma baboons adsorbs polar plant secondary metabolites representative of those found in their diet.

Geophagy, the deliberate consumption of earth materials, is common among humans and animals. However, its etiology and function(s) remain poorly understood. The major hypotheses about its adaptive functions are the supplementation of essential elements and the protection against temporary and chronic gastrointestinal (GI) distress. Because much less work has been done on the protection hypothesis, we investigated whether soil eaten by baboons protected their GI tract from plant secondary metabolites (PSMs) and described best laboratory practices for doing so. We tested a soil that baboons eat/preferred, a soil that baboons never eat/non-preferred, and two clay minerals, montmorillonite a 2:1 clay and kaolinite a 1:1 clay. These were processed using a technique that simulated physiological digestion. The phytochemical concentration of 10 compounds representative of three biosynthetic classes of compounds found in the baboon diet was then assessed with and without earth materials using high-performance liquid chromatography with diode-array detection (HPLC-DAD). The preferred soil was white, contained 1% halite, 45% illite/mica, 14% kaolinite, and 0.8% sand; the non-preferred soil was pink, contained 1% goethite and 1% hematite but no halite, 40% illite/mica, 19% kaolinite, and 3% sand. Polar phenolics and alkaloids were generally adsorbed at levels 10× higher than less polar terpenes. In terms of PSM adsorption, the montmorillonite was more effective than the kaolinite, which was more effective than the non-preferred soil, which was more effective than the preferred soil. Our findings suggest that HPLC-DAD is best practice for the assessment of PSM adsorption of earth materials due to its reproducibility and accuracy. Further, soil selection was not based on adsorption of PSMs, but on other criteria such as color, mouth feel, and taste. However, the consumption of earth containing clay minerals could be an effective strategy for protecting the GI tract from PSMs.

Preclinical in vivo and in vitro comparison of the translocator protein PET ligands [18F]PBR102 and [18F]PBR111.

PURPOSE: To determine the metabolic profiles of the translocator protein ligands PBR102 and PBR111 in rat and human microsomes and compare their in vivo binding and metabolite uptake in the brain of non-human primates (Papio hamadryas) using PET-CT. METHODS: In vitro metabolic profiles of PBR102 and PBR111 in rat and human liver microsomes were assessed by liquid chromatography-tandem mass spectrometry. [18F]PBR102 and [18F]PBR111 were prepared by nucleophilic substitution of their corresponding p-toluenesulfonyl precursors with [18F]fluoride. List mode PET-CT brain imaging with arterial blood sampling was performed in non-human primates. Blood plasma measurements and metabolite analysis, using solid-phase extraction, provided the metabolite profile and metabolite-corrected input functions for kinetic model fitting. Blocking and displacement PET-CT scans, using PK11195, were performed. RESULTS: Microsomal analyses identified the O-de-alkylated, hydroxylated and N-de-ethyl derivatives of PBR102 and PBR111 as the main metabolites. The O-de-alkylated compounds were the major metabolites in both species; human liver microsomes were less active than those from rat. Metabolic profiles in vivo in non-human primates and previously published rat experiments were consistent with the microsomal results. PET-CT studies showed that K1 was similar for baseline and blocking studies for both radiotracers; VT was reduced during the blocking study, suggesting low non-specific binding and lack of appreciable metabolite uptake in the brain. CONCLUSIONS: [18F]PBR102 and [18F]PBR111 have distinct metabolic profiles in rat and non-human primates. Radiometabolites contributed to non-specific binding and confounded in vivo brain analysis of [18F]PBR102 in rodents; the impact in primates was less pronounced. Both [18F]PBR102 and [18F]PBR111 are suitable for PET imaging of TSPO in vivo. In vitro metabolite studies can be used to predict in vivo radioligand metabolism and can assist in the design and development of better radioligands.

N-acetylcysteine in preclinical mouse and baboon models of thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura (TTP) is a microangiopathic disorder diagnosed by thrombocytopenia and hemolytic anemia, associated with a deficiency in von Willebrand factor (VWF)-cleaving protease ADAMTS13. Current treatment is based on plasma infusion for congenital TTP, or plasma exchange, often in combination with immunosuppressive agents, for acquired TTP. These treatment methods are not always effective; therefore, new treatment methods are highly necessary. N-acetylcysteine (NAC), an FDA-approved anti-mucolytic agent, is a possible new treatment strategy for TTP, as it was demonstrated to reduce disulfide bonds in VWF, thereby decreasing VWF multimers size and hence their prothrombotic potential. We investigated whether NAC, without concurrent plasma exchange and immunosuppressive therapy, is effective in preventing and resolving TTP signs, using well-established murine and baboon models for TTP. In mice, prophylactic administration of NAC was effective in preventing severe TTP signs. This in vivo finding was supported by in vitro data demonstrating the VWF multimer-reducing properties of NAC in solution. Nonetheless, in both mice and baboons, administration of NAC was not effective in resolving preexisting TTP signs; thrombocytopenia, hemolytic anemia, and organ damage could not be reversed, as thrombus resolution was not achieved. Failure to improve clinical outcome occurred even though a reduction in VWF multimers was observed, demonstrating that NAC was efficient in reducing disulfide bonds in circulating VWF multimers. In conclusion, prophylactic administration of NAC, without concurrent plasma exchange, was effective in preventing severe TTP signs in mice, but NAC was not effective in resolving preexistent acute TTP signs in mice and baboons.

Imaging α4ß2 Nicotinic Acetylcholine Receptors (nAChRs) in Baboons with [18F]XTRA, a Radioligand with Improved Specific Binding in Extra-Thalamic Regions.

PURPOSE: Currently available positron-emitting radiotracers for imaging of the α4ß2 subtype of nicotinic acetylcholine receptors (nAChRs) exhibit high and moderate specific binding in the thalamus and extra-thalamic brain regions, respectively. In many neuropsychiatric disorders, α4ß2-nAChRs are altered in the extra-thalamic brain regions, but not necessarily in the thalamus. The purpose of this study was to evaluate [18F]XTRA, a new α4ß2-nAChR positron emission tomography (PET) radioligand with improved specific binding in extra-thalamic brain regions, in non-human primates. PROCEDURES: The regional distribution of [18F]XTRA in the brain of Papio anubis baboons was evaluated in baseline and blocking experiments. Various PET modeling procedures were used for determination of volume of distribution (V T), binding potential (BPND), and receptor occupancy. Radiation dosimetry for [18F]XTRA was studied in male CD-1 mice and extrapolated to human dosimetry estimates using OLINDA/EXM software. RESULTS: [18F]XTRA was synthesized using an automated radiochemistry module with 25 % decay-corrected radiochemical yield. [18F]XTRA readily enters the baboon brain and specifically labels α4ß2-nAChRs. Mathematical modeling demonstrates high binding potential values (BPND = 7 and 1.3 in the thalamus and frontal cortex, respectively). A PET scanning time of 90-120 min was sufficient to obtain stable V T values in the extra-thalamic regions. The extrapolated human effective dose was 0.041 mSv/MBq (0.15 Rem/mCi). CONCLUSION: [18F]XTRA exhibits improved specific binding in the baboon brain including extra-thalamic regions and it is considered radiologically acceptable for human studies. Further evaluations of [18F]XTRA in human subjects are under way.

Serum Vitamin D Concentrations in Baboons (Papio spp.) during Pregnancy and Obesity.

Obesity is associated with vitamin D deficiency, which can lead to serious problems during pregnancy. However, the mechanisms of the deficiency and guidelines for vitamin D supplementation during pregnancy are not established yet, and variations in environmental exposures combined with the difficulties of performing research in pregnant women are obstacles in the evaluation of vitamin D metabolism. Baboons (Papio spp.) are an excellent, well-established model for reproductive research and represent a unique opportunity to study vitamin D metabolism in a controlled environment. This study used secondary data and specimen analysis as well as a novel experimental design to evaluate pregnant and nonpregnant baboons that were or were not exposed to sunlight while they were obese and after weight reduction. Daily D3 intake was 71% higher in nonpregnant obese baboons than in their nonobese counterparts, but serum vitamin D concentrations did not differ between these populations. In addition, serum 25-hydroxyvitamin D concentrations correlated negatively with the obesity index. This report is the first to show the effect of obesity and pregnancy on vitamin D concentrations in a NHP population. These data underline the importance of adequate vitamin D supplementation in obese animals.

Radiosynthesis and in Vivo Evaluation of Neuropeptide Y5 Receptor (NPY5R) PET Tracers.

Neuropeptide Y receptor type 5 (NPY5R) is a G-protein coupled receptor (GPCR) that belongs to the subfamily of neuropeptide receptors (NPYR) that mediate the action of endogenous neuropeptide Y (NPY). Animal models and preclinical studies indicate a role for NPY5R in the pathophysiology of depression, anxiety, and obesity and as a target of potential therapeutic drugs. To better understand the pathophysiological involvement of NPY5R, and to measure target occupancy by potential therapeutic drugs, it would be advantageous to measure NPY5R binding in vivo by positron emission tomography (PET). Four potent and selective NPY5R antagonists were radiolabeled via nucleophilic aromatic substitution reactions with [(18)F]fluoride. Of the four radioligands investigated, PET studies in anesthetized baboons showed that [(18)F]LuAE00654 ([(18)F]N-[trans-4-({[4-(2-fluoropyridin-3-yl)thiazol-2-yl]amino}methyl)cyclohexyl]propane-2-sulfonamide) penetrates blood brain barrier (BBB) and a small amount is retained in the brain. Slow metabolism of [(18)F]LuAE00654 was observed in baboon plasma. Blocking studies with a specific NPY5R antagonist demonstrated up to 60% displacement of radioactivity in striatum, the brain region with highest NPY5R binding. Our studies suggest that [(18)F]LuAE00654 can be a potential PET radiotracer for the quantification and occupancy studies of NPY5R drug candidates.

Comparative evaluation of two glycine transporter 1 radiotracers [11C]GSK931145 and [18F]MK-6577 in baboons.

Glycine transporter type-1 (GlyT1) has been proposed as a target for drug development for schizophrenia. PET imaging with a GlyT1 specific radiotracer will allow for the measurement of target occupancy of GlyT1 inhibitors, and for in vivo investigation of GlyT1 alterations in schizophrenia. We conducted a comparative evaluation of two GlyT1 radiotracers, [(11) C]GSK931145, and [(18) F]MK-6577, in baboons. Two baboons were imaged with [(11) C]GSK931145 and [(18) F]MK-6577. Blocking studies with GSK931145 (0.3 or 0.2 mg/kg) were conducted to determine the level of tracer specific binding. [(11) C]GSK931145 and [(18) F]MK-6577 were synthesized in good yield and high specific activity. Moderately fast metabolism was observed for both tracers, with ∼ 30% of parent at 30 min post-injection. In the brain, both radiotracers showed good uptake and distribution profiles consistent with regional GlyT1 densities. [(18) F]MK-6577 displayed higher uptake and faster kinetics than [(11) C]GSK931145. Time activity curves were well described by the two-tissue compartment model. Regional volume of distribution (VT ) values were higher for [(18) F]MK-6577 than [(11) C]GSK931145. Pretreatment with GSK931145 reduced tracer uptake to a homogeneous level throughout the brain, indicating in vivo binding specificity and lack of a reference region for both radiotracers. Linear regression analysis of VT estimates between tracers indicated higher specific binding for [(18) F]MK-6577 than [(11) C]GSK931145, consistent with higher regional binding potential (BPND ) values of [(18) F]MK-6577 calculated using VT from the baseline scans and non-displaceable distribution volume (VND ) derived from blocking studies. [(18) F]MK-6577 appears to be a superior radiotracer with higher brain uptake, faster kinetics, and higher specific binding signals than [(11) C]GSK931145.