8 research outputs found
Improved Reagents for Newborn Screening of Mucopolysaccharidosis Types I, II, and VI by Tandem Mass Spectrometry
Tandem mass spectrometry for the
multiplex and quantitative analysis
of enzyme activities in dried blood spots on newborn screening cards
has emerged as a powerful technique for early assessment of lysosomal
storage diseases. Here we report the design and process-scale synthesis
of substrates for the enzymes α-l-iduronidase, iduronate-2-sulfatase,
and <i>N</i>-acetylgalactosamine-4-sulfatase that are used
for newborn screening of mucopolysaccharidosis types I, II, and VI.
The products contain a bisamide unit that is hypothesized to readily
protonate in the gas phase, which improves detection sensitivity by
tandem mass spectrometry. The products contain a benzoyl group, which
provides a useful site for inexpensive deuteration, thus facilitating
the preparation of internal standards for the accurate quantification
of enzymatic products. Finally, the reagents are designed with ease
of synthesis in mind, thus permitting scale-up preparation to support
worldwide newborn screening of lysosomal storage diseases. The new
reagents provide the most sensitive assay for the three lysosomal
enzymes reported to date as shown by their performance in reactions
using dried blood spots as the enzyme source. Also, the ratio of assay
signal to that measured in the absence of blood (background) is superior
to all previously reported mucopolysaccharidosis types I, II, and
VI assays
Newborn Screening for Mucopolysaccharidoses: Results of a Pilot Study with 100 000 Dried Blood Spots
Pharmacological characterization, structural studies, and in vivo activities of anti-chagas disease lead compounds derived from Tipifarnib.
Chagas disease, caused by the protozoan pathogen Trypanosoma cruzi, remains a challenging infection due to the unavailability
of safe and efficacious drugs. Inhibitors of the trypanosome sterol 14 -demethylase enzyme (CYP51), including azole antifungal
drugs, are promising candidates for development as anti-Chagas disease drugs. Posaconazole is under clinical investigation for
Chagas disease, although the high cost of this drug may limit its widespread use. We have previously reported that the human
protein farnesyltransferase (PFT) inhibitor tipifarnib has potent anti-T. cruzi activity by inhibiting the CYP51 enzyme. Furthermore,
we have developed analogs that minimize the PFT-inhibitory activity and enhance the CYP51 inhibition. In this paper, we
describe the efficacy of the lead tipifarnib analog compared to that of posaconazole in a murine model of T. cruzi infection. The
plasma exposure profiles for each compound following a single oral dose in mice and estimated exposure parameters after repeated
twice-daily dosing for 20 days are also presented. The lead tipifarnib analog had potent suppressive activity on parasitemia
in mice but was unsuccessful at curing mice, whereas posaconazole as well as benznidazole cured 3 of 5 and 4 of 6 mice,
respectively. The efficacy results are consistent with posaconazole having substantially higher predicted exposure than that of
the tipifarnib analog after repeat twice-daily administration. Further changes to the tipifarnib analogs to reduce plasma clearance
are therefore likely to be important. A crystal structure of a trypanosomal CYP51 bound to a tipifarnib analog is reported
here and provides new insights to guide structure-based drug design for further optimized compounds