Accumulation of methotrexate and methotrexate polyglutamates in lymphoblasts at diagnosis of childhood acute lymphoblastic leukemia: a pilot prognostic factor analysis

Lymphoblasts in bone marrow samples, obtained from 43 children with acute lymphoblastic leukemia at diagnosis, were incubated with 1.0 mumols/L [3H] methotrexate for 24 hours in vitro. Nonexchangeable methotrexate and methotrexate polyglutamates were separated and quantitated. Event-free survival at 5 years was 38% +/- 9% for all 43 patients (27 failures), and 44% +/- 10% for the 35 with non-T, non-B- cell acute lymphoblastic leukemia (20 failures). Of these 35 children, those whose lymphoblasts accumulated more than 100 pmol methotrexate and 500 pmol methotrexate polyglutamates per billion cells experienced better 5-year event-free survival than those whose lymphoblasts did not (65% +/- 12% v 22% +/- 9%, P = .010). This difference characterized "good-risk" patients who were female (P = .014), less than age 7 at diagnosis (P = .005), or had low initial white blood cell counts (less than 20 X 10(9)/L, P = .018). Findings were similar for the 43 children with acute lymphoblastic leukemia and for the "good-risk" children in this total group. Thus, the ability of lymphoblasts to accumulate methotrexate and form methotrexate polyglutamates may be important to the curative properties of current therapy of acute lymphoblastic leukemia in children, particularly for "good-risk" patients. In such patients, inherent rather than acquired drug resistance may be the initial event leading to treatment failure.     

Expression of protocadherin-γC4 protein in the rat brain

It has been proposed that the combinatorial expression of γ-protocadherins (Pcdh-γs) and other clustered protocadherins (Pcdhs) provides a code of molecular identity and individuality to neurons, which plays a major role in the establishment of specific synaptic connectivity and formation of neuronal circuits. Particular attention has been directed to the Pcdh-γ family, for which experimental evidence derived from Pcdh-γ-deficient mice shows that they are involved in dendrite self-avoidance, synapse development, dendritic arborization, spine maturation, and prevention of apoptosis of some neurons. Moreover, a triple-mutant mouse deficient in the three C-type members of the Pcdh-γ family (Pcdh-γC3, Pcdh-γC4, and Pcdh-γC5) shows a phenotype similar to the mouse deficient in whole Pcdh-γ family, indicating that the latter is largely due to the absence of C-type Pcdh-γs. The role of each individual C-type Pcdh-γ is not known. We have developed a specific antibody to Pcdh-γC4 to reveal the expression of this protein in the rat brain. The results show that although Pcdh-γC4 is expressed at higher levels in the embryo and earlier postnatal weeks, it is also expressed in the adult rat brain. Pcdh-γC4 is expressed in both neurons and astrocytes. In the adult brain, the regional distribution of Pcdh-γC4 immunoreactivity is similar to that of Pcdh-γC4 mRNA, being highest in the olfactory bulb, dentate gyrus, and cerebellum. Pcdh-γC4 forms puncta that are frequently apposed to glutamatergic and GABAergic synapses. They are also frequently associated with neuron-astrocyte contacts. The results provide new insights into the cell recognition function of Pcdh-γC4 in neurons and astrocytes.     

Changes in the contractile response of arteires and veins from hypertensive rabbits to sympathetic nerve activity: assessment of some postsynaptic influences.

Contractile responses to field stimulation of intramural nerves of arteries and veins taken from rabbits made hypertensive by partial constriction of the abdominal aorta have been related to the carotid artery pressure. The increase in contraction of cephalic and short saphenous veins with rise in carotid artery pressure can be accounted for by an increase in sensitivity of the alpha-adrenergic receptor. The neurogenic contraction of the ear artery increased with carotid artery pressure rise. Changes in some of the extraneuronal factors that influence transmitter distribution and disposition in the tunica media were examined. In hypertensive animals, the percentage of released adrenergic transmitter entering the vessel wall might be expected to decrease due to an increase in medial thickness. However, this percentage was not significantly altered in the ear artery probably due, in part, to a concomitant increase in medial permeability to the transmitter. Extraneuronal transmitter disposition factors, i.e. extraneuronal uptake, monoamine oxidase, and catechol-O-methyltransferase activity are directly related to the wet weight of the vessel wall. Thus, their contribution to transmitter disposition would be expected to increase with increase in vessel wall thickness and tend to reduce the response to sympathetic activity. As the contractile response increased in the hypertensive vessels despite such changes, the increase in effector cell mass and density of neuronal terminal plexus, shown previously to increase with hypertension, are more important than these other considerations.     

Influence of H-2 antigen expression on killer T cell specificity, differentiation, and induction.

Murine cytotoxic T lymphocytes (CTL) and helper cells are H-2 antigen restricted in their specificity: recognition of foreign antigen by these cells requires the concomitant recognition of self-H-2 molecules. Which H-2 antigens T cells treat as "self" is determined by the particular H-2 antigens expressed on radioresistant cells of the thymus in which these T cells mature. Using tetraparental [(P1 + P2) leads to F1] radiation chimeras with in situ F1 thymuses, we have found that the H-2 genotype of the stem cells does not influence their H-2 restriction specificity. This has allowed us to use tetraparental chimeras that have been thymectomized and grafted with parental (P1, P2, or both) thymus lobes to study the requirements for H-2-restricted T--T interactions during CTL ontogeny and induction. In animals that have received thymus grafts of both parental origins, CTL display no preference for maturation within a syngeneic thymus graft, a finding that is not compatible with a suggested requirement for intrathymic H-2-restricted T--T interactions in the maturation of precursor CTL. We have also grafted thymectomized tetraparental radiation chimeras with thymus grafts from only one parent to compare the induction of P1 and P2 CTL in environments in which peripheral (extrathymic) T cell interactions are restricted to one H-2 haplotype. Again, we find no evidence for preferential induction of CTL precursors syngeneic to the thymus graft, contrary to expectation if CTL induction requires that T helper cells restricted to thymic H-2 antigens interact directly with precursor CTL. In those animals with one parental thymus graft, there is variability in the ratios of P1 and P2 cells induced with several antigens, a finding that may be indicative of an H-2-restricted suppression mechanism operating in the periphery.     

T cells respond preferentially to antigens that are similar to self H-2.

We have constructed bone marrow irradiation chimeras to investigate the influence of self antigens on the specificity of the T lymphocyte receptor repertoire. Bone marrow cells from (A X B)F1 mice heterozygous for the major histocompatibility genes were allowed to mature into T cells in irradiated parent A or parent B strains. More than 8 weeks after irradiation, when the lymphoid system had regenerated from the F1 stem cells, the degree of T cell reactivity to mutant major histocompatibility antigens, A', was assessed. It was found that T cells that had matured in the irradiated A mice, [F1 leads to A] chimeras, responded better to A' antigen than did T cells from the [F1 leads to B] chimeras. Because the mutant histocompatibility antigen A' is very similar in structure to A, differing only by one or a few residues, this suggests that the T cell repertoire in [F1 leads to parent] chimeras reacts preferentially with foreign antigens that are slight variants of the self antigens expressed on radiation-resistant cells--probably cells in the thymus.     

Precision medicine in chronic disease management: The multiple sclerosis BioScreen

We present a precision medicine application developed for multiple sclerosis (MS): the MS BioScreen. This new tool addresses the challenges of dynamic management of a complex chronic disease; the interaction of clinicians and patients with such a tool illustrates the extent to which translational digital medicine—that is, the application of information technology to medicine—has the potential to radically transform medical practice. We introduce 3 key evolutionary phases in displaying data to health care providers, patients, and researchers: visualization (accessing data), contextualization (understanding the data), and actionable interpretation (real‐time use of the data to assist decision making). Together, these form the stepping stones that are expected to accelerate standardization of data across platforms, promote evidence‐based medicine, support shared decision making, and ultimately lead to improved outcomes. Ann Neurol 2014;76:633–642     

Lymphangiomas in children: MR imaging

Seventeen lymphangiomas in 15 patients were imaged with magnetic resonance (MR) to define the nature, extent, and anatomic relationships of these lesions. The MR and pathologic findings were then compared to determine the histologic basis for the signal-intensity characteristics of these lesions. The signal intensity of 13 lesions was similar to or slightly less than that of muscle on T1-weighted images and greater than that of fat on T2-weighted images. This appearance correlated with the presence of ectatic lymphatic channels containing clear fluid on histologic section. Four lymphangiomas had high signal intensity, approximately equal to that of fat, on T1-weighted images, reflecting the presence of clotted blood or small cystic spaces with a higher ratio of fat to fluid. Sixteen of 17 lesions had visible septations on MR images. The authors' experience suggests that most lymphangiomas have a characteristic appearance on MR images. The information obtained with MR imaging can help in providing a preoperative diagnosis, in planning surgical resection, and in defining recurrence.