A specific enzyme assay for aminopeptidase M in rat brain

Gillespie, T. J.; Konings, P. N. M.; Merrill, Bradley J.; Davis, Thomas P.

doi:10.1016/0024-3205(92)90161-h

Cited by 26 publications

(14 citation statements)

References 15 publications

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“…The supernatant was separated and stored at À80 C until required. The 15% mouse brain homogenate was prepared following a previously reported protocol (Gillespie et al, 1992;Mallareddy et al, 2011). Briefly, mouse brains were isolated, pooled, homogenized with 50 mM Tris-HCl (pH 7.4), and stored at À80 C until used.…”

Section: Metabolic Stability Studiesmentioning

confidence: 99%

The improved blood–brain barrier permeability of endomorphin-1 using the cell-penetrating peptide synB3 with three different linkages

Liu¹,

Zhang²,

Ma³

et al. 2014

International Journal of Pharmaceutics

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Section: Metabolic Stability Studiesmentioning

confidence: 99%

The improved blood–brain barrier permeability of endomorphin-1 using the cell-penetrating peptide synB3 with three different linkages

Liu¹,

Zhang²,

Ma³

et al. 2014

International Journal of Pharmaceutics

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“…The effect of brain membraneassociated enzymes on the degradation of nifurtimox was examined over 3 h at 37°C (Thomas et al, 1997). Adult BALB/c mice were anesthetized as described earlier, and twice-washed membranes were prepared from whole brains (minus the cerebellum) as described previously (Gillespie et al, 1992). Brain homogenate was suspended in 50 mM Tris buffer to a final protein concentration of 3.51 mg/ml and frozen until use.…”

Section: Octanol-saline Partition Coefficient and Protein Binding Meamentioning

confidence: 99%

The Distribution of Nifurtimox Across the Healthy and Trypanosome-Infected Murine Blood-Brain and Blood-Cerebrospinal Fluid Barriers

Jeganathan¹,

Sanderson²,

Dogruel³

et al. 2010

J Pharmacol Exp Ther

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Nifurtimox, an antiparasitic drug, is used to treat American trypanosomiasis (Chagas disease) and has shown promise in treating central nervous system (CNS)-stage human African trypanosomiasis (HAT; sleeping sickness). In combination with other antiparasitic drugs, the efficacy of nifurtimox against HAT improves, although why this happens is unclear. Studying how nifurtimox crosses the blood-brain barrier (BBB) and reaches the CNS may clarify this issue and is the focus of this study. To study the interaction of nifurtimox with the blood-CNS interfaces, we used the in situ brain/choroid plexus perfusion technique in healthy and trypanosome-infected mice and the isolated incubated choroid plexus. Results revealed that nifurtimox could cross the healthy and infected blood-brain and blood-cerebrospinal fluid (CSF) barriers (K in brain parenchyma was 50.8 Ϯ 9.0 l ⅐ min Ϫ1 ⅐ g Ϫ1 ). In fact, the loss of barrier integrity associated with trypanosome infection failed to change the distribution of [ 3 H]nifurtimox to any significant extent, suggesting there is not an effective paracellular barrier for [ 3 H]nifurtimox entry into the CNS. Our studies also indicate that [ 3 H]nifurtimox is not a substrate for P-glycoprotein, an efflux transporter expressed on the luminal membrane of the BBB. However, there was evidence of [ 3 H]nifurtimox interaction with transporters at both the blood-brain and blood-CSF barriers as demonstrated by cross-competition studies with the other antitrypanosomal agents, eflornithine, suramin, melarsoprol, and pentamidine. Consequently, CNS efficacy may be improved with nifurtimox-pentamidine combinations, but over time may be reduced when nifurtimox is combined with eflornithine, suramin, or melarsoprol.

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“…The supernatant was separated and stored at Ϫ80°C. The 15% mouse brain homogenate was prepared as described previously (Gillespie et al, 1992). Protein content of the suspension was confirmed by the method of Bradford (1976).…”

Section: Chemicalsmentioning

confidence: 99%

Utilization of Combined Chemical Modifications to Enhance the Blood-Brain Barrier Permeability and Pharmacological Activity of Endomorphin-1

Liu²,

Yao³

et al. 2006

J Pharmacol Exp Ther

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The endogenous -opioid receptor agonist, endomorphin (EM)-1, cannot be delivered into the central nervous system (CNS) in sufficient quantity to elicit analgesia when given systemically because it is severely restricted by the blood-brain barrier (BBB). To improve the physicochemical characteristics of EM-1 and subsequently achieve greater BBB permeation, we synthesized a series of EM-1 analogs by combining successful chemical modifications, including N-terminal cationization, Cterminal chloro-halogenation, and unnatural amino acid (D-Ala, Sar, and D-Pro-Gly) substitutions in position 2. Presently, their binding and bioassay activity, lipophilicity, stability, and antinociceptive activity were determined and compared. Guanidinoaddition and chloro-halogenation attenuated the -receptor affinity to some extent, but they demonstrated differences in the influence on stability. It appeared that guanidino-addition contributed to brain stability enhancement for the greater part, whereas chloro-halogenation together with amino acid substitutions in position 2 was of more importance for the stability enhancement in serum than in brain. Determination of the octanol/buffer coefficient revealed that chloro-halogenation did compromise the decreased lipophilicity caused by guanidinoaddition, and introduction of D-Ala as well as D-Pro-Gly, but not Sar, in place of L-Pro 2 , also increased the overall lipophilicity to some extent. Among the peptides tested, intracerebroventricular injection of guanidino-[D-Ala 2 , p-Cl-Phe 4 ]EM-1 showed the strongest analgesia, being 3 times more potent than the parent peptide. We also found that in comparison with EM-1, the four D-Ala-containing tetrapeptides and the chloro-halogenated DPro-Gly-containing pentapeptide elicited significant and prolonged central-mediated analgesia upon subcutaneous administration, indicating that more peptides reached the CNS, eliciting greater analgesic effect.

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A specific enzyme assay for aminopeptidase M in rat brain

Cited by 26 publications

References 15 publications

The improved blood–brain barrier permeability of endomorphin-1 using the cell-penetrating peptide synB3 with three different linkages

The improved blood–brain barrier permeability of endomorphin-1 using the cell-penetrating peptide synB3 with three different linkages

The Distribution of Nifurtimox Across the Healthy and Trypanosome-Infected Murine Blood-Brain and Blood-Cerebrospinal Fluid Barriers

Utilization of Combined Chemical Modifications to Enhance the Blood-Brain Barrier Permeability and Pharmacological Activity of Endomorphin-1

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