Preclinical to Clinical Translation of CNS Transporter Occupancy of TD-9855, a Novel Norepinephrine and Serotonin Reuptake Inhibitor

Background:

Monoamine reuptake inhibitors exhibit unique clinical profiles that reflect distinct engagement of the central nervous system (CNS) transporters.

Methods:

We used a translational strategy, including rodent pharmacokinetic/pharmacodynamic modeling and positron emission tomography (PET) imaging in humans, to establish the transporter profile of TD-9855, a novel norepinephrine and serotonin reuptake inhibitor.

Results:

TD-9855 was a potent inhibitor of norepinephrine (NE) and serotonin 5-HT uptake in vitro with an inhibitory selectivity of 4- to 10-fold for NE at human and rat transporters. TD-9855 engaged norepinephrine transporters (NET) and serotonin transporters (SERT) in rat spinal cord, with a plasma EC₅₀ of 11.7ng/mL and 50.8ng/mL, respectively, consistent with modest selectivity for NET in vivo.Accounting for species differences in protein binding, the projected human NET and SERT plasma EC₅₀ values were 5.5ng/mL and 23.9ng/mL, respectively. A single-dose, open-label PET study (4–20mg TD-9855, oral) was conducted in eight healthy males using the radiotracers [¹¹C]-3-amino-4- [2-[(di(methyl)amino)methyl]phenyl]sulfanylbenzonitrile for SERT and [¹¹C]-(S,S)-methylreboxetine for NET. The long pharmacokinetic half-life (30–40h) of TD-9855 allowed for sequential assessment of SERT and NET occupancy in the same subject. The plasma EC₅₀ for NET was estimated to be 1.21ng/mL, and at doses of greater than 4mg the projected steady-state NET occupancy is high (>75%). After a single oral dose of 20mg, SERT occupancy was 25 (±8)% at a plasma level of 6.35ng/mL.

Conclusions:

These data establish the CNS penetration and transporter profile of TD-9855 and inform the selection of potential doses for future clinical evaluation.     

Discrepancies in reverse ABO typing due to prozone

Three group O sera manifesting prozone in reverse ABO tests are reported. All were implicated in erroneous blood typing results. One sample failed to react with A1 red cells (RBCs) in immediate-spin (IS) tests, had anti-A and -B titers of 8192 and 2048, respectively, by indirect antiglobulin technique (IAT), and was from a diabetic patient; the parenteral administration of A substance present in porcine insulin is a possible cause of hyperimmunity in this case. The second sample was from the recipient of a single unit of group B fresh-frozen plasma; the serum anti-A and -B titers were 10,240 by IAT, but only weak reactions with A1 and B RBCs were noted in routine IS reverse typing tests; the hyperimmunity in the patient concerned was likely due to crossreacting anti-A, B stimulated by B-active glycoproteins and/or glycolipids in the transfused plasma. The third serum also had anti-A and anti-B IAT titers of 10,240 but did not react with A1 and B RBCs by IS; the hyperimmunity in this case may be related to sepsis from intestinal flora carrying A- and/or B-like antigens. These antibodies lysed A1 and/or B RBCs in tests incubated at room temperature (RT) and strongly agglutinated those RBCs by IS when diluted 10-fold with saline. The absence of the prozone phenomenon in tests with RBCs suspended in diluents containing EDTA is consistent with the previously published mechanism for anti-A prozone: namely, the steric hindrance of agglutination by the C1 component of human complement.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electronic verification of donor-recipient compatibility: the computer crossmatch

Background: This article describes standard operating procedures (SOPs) for a computer crossmatch to replace the immediate-spin crossmatch for ABO incompatibility between patient blood samples submitted for pretransfusion testing and the blood component selected for transfusion. These SOPs were developed following recent changes to the Standards for Blood Banks and Transfusion Services of the American Association of Blood Banks (AABB). Study Design and Methods: SOPs were developed, utilizing currently available software, for pretransfusion testing. The SOP for donor unit processing entails bar code entry of the unit number, component name, and ABO/Rh type; computer entry and interpretation of serologic reactions; warning of discrepancies between bar code-entered blood type and result interpretation; and quarantine of the donor unit in such instances. The SOP for patient sample testing requires bar code entry of specimen accession number, which accesses patient demographics; computer entry and interpretation of ABO/Rh tests; repeat blood typing at the time of crossmatch if only one patient blood type is on record; and warning if there are nonconcordant current and historical blood types. The computer crossmatch SOP requires bar code entry of specimen accession and donor unit numbers; release of group O red cells pending resolution of discrepancies; and immediate-spin crossmatch during computer downtime. Tables validated on- site prompt warning messages and prevent both computer crossmatch and release if blood components of the wrong ABO type are selected. Results: These SOPs meet the requirements of the 15th edition of the AABB Standards. Projected annual time savings at this institution are > 100,000 workload recording units. Further benefits include reduced patient sample volume requirements, less handling of biohazardous material, and elimination of unwanted positive or negative reactions associated with the immediate-spin crossmatch. Release of incompatible blood components when the wrong patient blood type is on record is addressed by requiring the use of group O red cells in the absence of two concordant blood types, one of which must be from a current sample. Conclusion: A combination of existing computer programs and carefully developed SOPs can provide a safe and efficient means of detecting donor-recipient incompatibility without performance of serologic crossmatch.     

干细胞诱导分化与糖尿病治疗

学术背景：对于丧失胰岛细胞功能的糖尿病患者来说，最根本的治疗方法是行胰腺移植或胰岛移植，但此法存在胰岛来源短缺及需要终生服用免疫抑制剂等问题。目的：充分认识干细胞在定向分化胰岛素分泌细胞及其在糖尿病细胞替代疗法中的作用。检索策略：由论文的研究人员应用计算机检索Pubmed、ISI Web of Knowledge、Blackwell Synergy数据库2000—01／2006—12的相关文献，检索词“stem cell，insulin producing cells，diabetes”，并限定文章语言种类为English。同时计算机检索中国期刊全文数据库2000—01/2006—12的相关文献，检索词“干细胞，胰岛素分泌细胞，糖尿病”，并限定文章语言种类为中文。此外手工检索相关干细胞中文书籍。共检索到111篇文献，对资料进行初审，纳入标准：人/鼠胚胎干细胞、成体干细胞定向分化胰岛素分泌细胞的研究，整理不同的诱导方法包括基因修饰、序贯的诱导因子等。排除标准：明显不随机的文献、Meta分析、重复性文献。文献评价：文献的来源主要是通过对人，鼠胚胎干细胞、成体干细胞定向分化胰岛素分泌细胞的研究进行汇总分析。所选用的30篇文献中，1篇为综述，其余均为临床或基础实验研究。资料综合：①干细胞以其极强的自我更新能力及多向分化潜能成为获得大量胰岛β细胞的最佳种子细胞来源。②目前已证实人／鼠胚胎干细胞可以在基因调控或条件诱导分化培养等情况下被诱导分化为胰岛素分泌细胞。③扩增及诱导胰腺干细胞分化是获得β细胞替代物的更直接的途径。但若将胰腺干细胞应用于临床，还需要做很多工作，如寻找最佳的扩增及诱导方案、最佳移植部位等。④胰腺外组织的前体细胞也因其可作为成体干细胞来源而受到关注，如肝干细胞、骨髓间充质干细胞。（函更新的研究着手于骨髓来源的干细胞、胎儿脐带血、脐带间充质干细胞及胎盘多潜能细胞等定向分化，以寻求更多的种子细胞来源应用于细胞替代疗法。结论：尽管目前应用干细胞治疗糖尿病研究处于动物实验阶段，但各种干细胞定向分化为胰岛β细胞的可能性为糖尿病患者点燃新的希望。深入了解胰腺个体发生机制及干细胞定向分化为胰岛β细胞分子调控机制，将加快糖尿病细胞治疗的研究进展。