JAK3 mutations and mitochondrial apoptosis resistance in T-cell acute lymphoblastic leukemia

Resistance to mitochondrial apoptosis predicts inferior treatment outcomes in patients with diverse tumor types, including T-cell acute lymphoblastic leukemia (T-ALL). However, the genetic basis for variability in this mitochondrial apoptotic phenotype is poorly understood, preventing its rational therapeutic targeting. Using BH3 profiling and exon sequencing analysis of childhood T-ALL clinical specimens, we found that mitochondrial apoptosis resistance was most strongly associated with activating mutations of JAK3. Mutant JAK3 directly repressed apoptosis in leukemia cells, because its inhibition with mechanistically distinct pharmacologic inhibitors resulted in reversal of mitochondrial apoptotic blockade. Inhibition of JAK3 led to loss of MEK, ERK and BCL2 phosphorylation, and BH3 profiling revealed that JAK3-mutant primary T-ALL patient samples were characterized by a dependence on BCL2. Treatment of JAK3-mutant T-ALL cells with the JAK3 inhibitor tofacitinib in combination with a spectrum of conventional chemotherapeutics revealed synergy with glucocorticoids, in vitro and in vivo. These findings thus provide key insights into the molecular genetics of mitochondrial apoptosis resistance in childhood T-ALL, and a compelling rationale for a clinical trial of JAK3 inhibitors in combination with glucocorticoids for patients with JAK3-mutant T-ALL.

A histological study of the use of agar as a delivery vehicle for alcohol or iron to rats

The supply of ethanol and other substances to the rat has necessitated the development of quite complex dietary preparation and feeding techniques. This study reports the use of ethanol/water solutions in conjunction with normal rat chow diet to provide up to 30 g/kg/day ethanol to study animals. By additionally supplying agar gels containing ethanol, voluntary intake of ethanol was raised to a possible maximum of 48 g/kg/day. Hepatic steatosis was produced in 7/18 rats supplied ethanol in this fashion. Agar gels were also used to provide carbonyl iron to rats and it produced grade 3 to 4 hepatocyte iron loading in all study animals. The study demonstrates a practical method for administering ethanol and iron to rats without altering normal dietary intake. Ethanol supplied in this way does produce hepatic injury in the rat.

Barriers to HIV testing and confidentiality: the concerns of HIV-positive and high-risk individuals

The authors report that individuals who are at highest risk of contracting HIV indicated the greatest concern about confidentiality and the greatest knowledge of local reporting laws. Although concern about confidentiality may not be cited as the most common reason to delay or defer testing, it is an important consideration for a minority of individuals--the very segment who are at highest risk of contracting HIV and are the most important targets of campaigns to encourage HIV testing. The particular concerns of this critical segment of the population at risk must be directly and carefully addressed and not lost in a general assessment of population-wide attitudes/concerns about HIV testing. Studies that examine individuals' concerns about HIV testing and privacy and do not stratify by level of HIV risk may obscure the important and heightened concerns of this most important subpopulation.