Imaging Mutant Huntingtin Aggregates: Development of a Potential PET Ligand

Mutant huntingtin (mHTT) protein carrying the elongated N-terminal polyglutamine (polyQ) tract misfolds and forms protein aggregates characteristic of Huntington's disease (HD) pathology. A high-affinity ligand specific for mHTT aggregates could serve as a positron emission tomography (PET) imaging biomarker for HD therapeutic development and disease progression. To identify such compounds with binding affinity for polyQ aggregates, we embarked on systematic structural activity studies; lead optimization of aggregate-binding affinity, unbound fractions in brain, permeability, and low efflux culminated in the discovery of compound 1, which exhibited target engagement in autoradiography (ARG) studies in brain slices from HD mouse models and postmortem human HD samples. PET imaging studies with ¹¹C-labeled 1 in both HD mice and WT nonhuman primates (NHPs) demonstrated that the right-hand-side labeled ligand [¹¹C]-1R (CHDI-180R) is a suitable PET tracer for imaging of mHTT aggregates. [¹¹C]-1R is now being advanced to human trials as a first-in-class HD PET radiotracer.

[Model of eradication of tuberculosis in children in an area with high epidemiological potential]

In the territory of the Drajna TB dispensary, in the Prahova County, a series of complex measures have been experimented in the course of the second trimester of 1972, intending to prevent and to eliminate tuberculosis in children. Of the 31,731 children aged between 1 and 14 years, 29,496 have been tested with 2 units of PPD-IC65 (93 percent). A proportion of 12,6 percent of those tested presented reactions of more than 10 mm in diameter and 22,779 were vaccinated with BCG (Pasteur-Paris strain). The radiological pulmonary control of the reactors allowed for the detection of 24 cases of tuberculosis all of them new and asymptomatic. The efficiency of the detection was of 0,8 new cases per 1,000 tuberculin tested children or of 0,4 new cases per 100 of reactors that had been x-ray examined. This prophylactic action was repeated in 1973 in 2,219 children aged between 1 and 2-1/2 years that had been ommited in the preceding year and 4 new cases of tuberculosis were detected. In the medical districts in which there was a high prevalence of the children infection total radiophotographic case finding of the adult population was carried out. The result was a doubling of the TB incidence in children in 1972 followed by a 5-fold reduction of the indicators in 1973. The severe forms and death through tuberculosis in children have disappeared. The risk to develop the disease in BCG vaccinated children was reduced to 4,4 0/0000 per year. It is estimated that a generalization over the whole of the county of these prophylactic measures, as applied in the Drajna territory, under the form of a mass campaign, will allow for an improvement of the epidemiometric indicators in children in a relatively short time.