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.     

Shwachman syndrome: Exocrine pancreatic dysfunction and variable phenotypic expression

BACKGROUND & AIMS: Shwachman syndrome is an inherited condition with multisystemic abnormalities, including exocrine pancreatic dysfunction. The aim of this study was to evaluate the occurrence and progression of features in a large cohort of patients. METHODS: Clinical records of 25 patients with Shwachman syndrome were reviewed. RESULTS: Mean birth weight (2.92 +/- 0.51 kg) was at the 25th percentile. However, by 6 months of age, mean heights and weights were less than the 5th percentile. After 6 months of age, growth velocity was normal. Severe fat maldigestion due to pancreatic insufficiency was present in early life (fecal fat, 26% +/- 17% of fat intake; age, < 2 years). Serial assessment of exocrine pancreatic function showed persistent deficits of enzyme secretion, but 45% of patients showed moderate age-related improvements leading to pancreatic sufficiency. Neutropenia was the most common hematologic abnormality (88%), but leukopenia, thrombocytopenia, and anemia were also frequently encountered. Patients with hypoplasia of all three bone marrow cellular lines (n = 11) had the worst prognosis; 5 patients died, 2 of sepsis and 3 of acute myelogenous leukemia. Other findings included hepatomegaly and/or abnormal liver function test results and skeletal abnormalities. CONCLUSIONS: A wide and varied spectrum of phenotypic abnormalities among patients with Shwachman syndrome is described. Pancreatic acinar dysfunction is an invariable abnormality. Patients with severe bone marrow involvement may have a guarded prognosis. (Gastroenterology 1996 Dec;111(6):1593-602)     

Red cell membrane stiffness in iron deficiency

The purpose of this study was to characterize red blood cell (RBC) deformability by iron deficiency. We measured RBC deformability to ektacytometry, a laser diffraction method for determining the elongation of suspended red cells subjected to shear stress. Isotonic deformability of RBC from iron-deficient human subjects was consistently and significantly lower than that of normal controls. In groups of rats with severe and moderate dietary iron deficiency, RBC deformability was also reduced in proportion to the severity of iron deficiency. At any given shear stress value, deformability of resealed RBC ghosts from both iron-deficient humans and rats was lower than that of control ghosts. However, increase of applied shear stress resulted in progressive increase in ghost deformation, indicating that ghost deformability was primarily limited by membrane stiffness rather than by reduced surface area-to-volume ratio. This was consistent with the finding that iron-deficient cells had a normal membrane surface area. In addition, the reduced mean corpuscular hemoglobin concentration (MCHC) and buoyant density of the iron-deficient rat cells indicated that a high hemoglobin concentration was not responsible for impaired whole cell deformability. Biochemical studies of rat RBC showed increased membrane lipid and protein crosslinking and reduced intracellular cation content, findings that are consistent with in vivo peroxidative damage. RBC from iron-deficient rats incubated in vitro with hydrogen peroxide showed increased generation of malonyldialdehyde, an end-product of lipid peroxidation, compared to control RBC. Taken together, these findings suggest that peroxidation could contribute in part to increased membrane stiffness in iron- deficient RBC. This reduced membrane deformability may in turn contribute to impaired red cell survival in iron deficiency.     

Evaluation of retinopathy of prematurity screening in reverse Kangaroo Mother Care: a pilot study

Purpose

To evaluate retinopathy of prematurity (ROP) screening practice in reverse Kangaroo Mother Care (R-KMC) with respect to stress and pain to the infant.

Methods

In a pilot study we evaluated ROP screening practice in R-KMC in 20 babies at risk of ROP. The R-KMC differed from the conventional KMC with respect to the baby position where the baby lay supine on mother''s chest. With the mother lying supine and the baby in R-KMC position, screening examinations were done with indirect ophthalmoscope. The outcome measures included stress (quantified by pulse, respiration, and oxygen saturation) and pain to the baby by observing facial expression (eye squeezing, crying, and brow bulge). The heart rate, respiratory rate, and SpO2 (%) were compared before and immediately after the procedure using paired t-test.

Result

Mean (±SD) gestational age and birth weight were 30.8±2.3 weeks and 1362.5±253.9 g, respectively. During examination in R- KMC position 8 babies (40%) were completely relaxed (no eye squeezing and crying), 10 (50%) were partially relaxed (no brow bulge) and 2 babies (10%) were not relaxed. A change in heart and respiration rate both by 10 per minute was recorded in 12 (60%) and 10 (50%) babies, respectively. Five babies (25%) had reduction in blood oxygen concentration below 92%. The majority of the mothers (19 of 20) were relaxed.

Conclusion

ROP screening in R-KMC can be a baby friendly screening practice with respect to stress and pain to the infant and needs further evaluation in a larger cohort.     

Nosocomial diarrhoea

Toroviruses have been reported as a new cause of nosocomial viral diarrhoea, and the role of astroviruses has been further elucidated. Polymerase chain reaction methods promise to improve the diagnosis and understanding of the aetiology and control of hospital-acquired viral gastroenteritis. A clearer picture of the impact and extent of Clostridium difficile diarrhoea has emerged, and several control measures have been described. An epidemic Clostridium difficile strain and toxin A-deficient strains have been reported. There is growing evidence that enterotoxin-producing Clostridium perfringens can also cause antibiotic-associated diarrhoea.     

Laparoscopic Transplantation Following Transvaginal Insertion of the Kidney: Description of Technique and Outcome

Laparoscopic kidney transplantation (LKT) is well accepted modality of treatment for ESRD patients at our center. Usually, the kidney is inserted through small Pfannenstiel incision. With the permission of the Internal Review Board, we carried out LKT in eight female recipients following insertion of the kidney through the vagina. The kidney was procured by the retroperitoneoscopic approach. Antibiotic prophylaxis was given. All cases were carried out successfully with immediate graft function and 100% graft and patient survival at 1 year of follow‐up. Estimated glomerular filtration rate at 1 month and 1 year was similar to eight randomly selected female recipients who underwent open kidney transplantation (OKT). No analgesia was required in seven out of eight patients after the 3rd postoperative day. In summary, vaginal insertion of kidney and LKT is safe and feasible in a selected group of patients. It is associated with better analgesia and has similar allograft function as compare to OKT.     

Assessment of Mediastinal Lymph Node Size in Pneumococcal Pneumonia with Bacteremia

Introduction

The significance of mediastinal lymphadenopathy in bacterial pneumonia is unclear.

Methods

We performed a retrospective analysis of mediastinal lymph node size determined by chest CT in patients with bacteremic pneumococcal pneumonia. All patients who had positive blood cultures for streptococcus pneumonia over an 11-year period and had a chest CT scan (index CT) within 2 weeks of the positive blood culture were included in the study. Two thoracic radiologists and one pulmonologist independently examined the index CT plus any chest CT scans performed prior (pre-CT) or after (post-CT) the bacteremic episode.

Results

The study cohort of 49 patients was 57% male, 65% White, with mean age of 53 (SD = 20) years. Mediastinal lymphadenopathy was detected in 25/49 (51%) of the cases. The mean size of the largest mediastinal lymph node in short axis was 0.99 (SD = 0.71), ranging from 0.0 to 2.05 cm. There was no correlation noted between the number of lobes involved with pneumonia, and the size of the largest mediastinal lymph node (p = 0.33) or the number of pathologically enlarged mediastinal lymph nodes (p = 0.08). There was a statistically significant increase in the mean size of the largest lymph node between the pre-CT and index-CT group (p = 0.02), and decrease between the index-CT group and the post-CT (p = 0.03).

Conclusion

Pneumococcal pneumonia with bacteremia is associated with mild mediastinal lymph node enlargement. The presence of marked mediastinal lymphadenopathy (short axis LN size > 2 cm) should not be assumed from pneumococcal pneumonia.