DNA polymerase ␣-primase is known to be phosphorylated in human and yeast cells in a cell cycledependent manner on the p180 and p68 subunits. Here we show that phosphorylation of purified human DNA polymerase ␣-primase by purified cyclin A/cdk2 in vitro reduced its ability to initiate simian virus 40 (SV40) DNA replication in vitro, while phosphorylation by cyclin E/cdk2 stimulated its initiation activity. Tryptic phosphopeptide mapping revealed a family of p68 peptides that was modified well by cyclin A/cdk2 and poorly by cyclin E/cdk2. The p180 phosphopeptides were identical with both kinases. By mass spectrometry, the p68 peptide family was identified as residues 141 to 160. Cyclin A/cdk2-and cyclin A/cdc2-modified p68 also displayed a phosphorylation-dependent shift to slower electrophoretic mobility. Mutation of the four putative phosphorylation sites within p68 peptide residues 141 to 160 prevented its phosphorylation by cyclin A/cdk2 and the inhibition of replication activity. Phosphopeptide maps of the p68 subunit of DNA polymerase ␣-primase from human cells, synchronized and labeled in G 1 /S and in G 2 , revealed a cyclin E/cdk2-like pattern in G 1 /S and a cyclin A/cdk2-like pattern in G 2 . The slower-electrophoretic-mobility form of p68 was absent in human cells in G 1 /S and appeared as the cells entered G 2 /M. Consistent with this, the ability of DNA polymerase ␣-primase isolated from synchronized human cells to initiate SV40 replication was maximal in G 1 /S, decreased as the cells completed S phase, and reached a minimum in G 2 /M. These results suggest that the replication activity of DNA polymerase ␣-primase in human cells is regulated by phosphorylation in a cell cycle-dependent manner.DNA replication in eukaryotic cells takes place during a restricted period of the cell cycle, the S phase. The transition from G 1 into S phase in vertebrate cells is regulated by at least two cyclin-dependent kinases, cyclin E/cdk2 and cyclin A/cdk2 (reviewed in references 37 and 38). Cyclin E/cdk2 activity peaks in late G 1 (14, 26), while cyclin A/cdk2 activity appears later, with the onset of DNA synthesis (42,44,54). Microinjection of either an anti-cyclin A antibody, an antisense cyclin A expression plasmid (18,40,55,63), or an anti-cyclin E antibody (39) prevented the entry of cells into S phase, documenting the importance of these cyclins for the G 1 -to-S transition. Interestingly, microinjection of anti-cyclin A antibodies after S-phase entry appeared to have no effect on DNA synthesis or S-phase progression (40), despite evidence that cyclin A/cdk2 resides in replication foci (5, 6, 47). However, cyclin A/cdk2 activity rises throughout S phase, and cyclin A is required again for the S/G 2 transition (40). The requirement for cyclin E/cdk2 and cyclin A/cdk2 activities for entry into S phase implies that they are needed to modify protein substrates involved in initiation of DNA replication, but relatively little is known about how phosphorylation of physiological substrates triggers initiation of vert...

This study investigated the temporal dynamics of pancreas volume and microstructure in children and adolescents with recent-onset type 1 diabetes (T1D) and individuals without diabetes, including a subset expressing autoantibodies associated with the early stages of T1D. RESEARCH DESIGN AND METHODS MRI was performed in individuals with recent-onset stage 3 T1D (n = 51; median age 13 years) within 100 days after diagnosis (mean 67 days), 6 months, and 1 year postdiagnosis. Longitudinal MRI measurements were also made in similarly aged control participants (n = 57) and in autoantibody-positive individuals without diabetes (n = 20). The MRI protocol consisted of anatomical imaging to determine pancreas volume and quantitative MRI protocols interrogating tissue microstructure and composition. RESULTS Within 100 days of diabetes onset, individuals with T1D had a smaller pancreas (median volume 28.6 mL) than control participants (median volume 48.4 mL; P < 0.001), including when normalized by individual weight (P < 0.001). Longitudinal measurements of pancreas volume increased in control participants over the year, consistent with adolescent growth, but pancreas volume declined over the first year after T1D diagnosis (P < 0.001). In multiple autoantibody-positive individuals, the pancreas volume was significantly larger than that of the T1D cohort (P = 0.017) but smaller than that of the control cohort (P = 0.04). Diffusion-weighted MRI showed that individuals with recent-onset T1D had a higher apparent diffusion coefficient (P = 0.012), suggesting a loss of cellular structural integrity, with heterogeneous pancreatic distribution. CONCLUSIONS These results indicate that pancreas volume is decreased in stages 1, 2, and 3 of T1D and decreases during the first year after diabetes onset and that this loss of pancreatic volume is accompanied by microstructural changes. Reduced pancreas size has been noted in individuals with long-standing type 1 diabetes (T1D) (1-3). Because pancreatic islets comprise only 1-2% of the pancreatic mass, the reason for the smaller pancreas in T1D is not known, but changes in the exocrine pancreas are implicated. More recently, studies in adults with recent-onset

WHAT'S KNOWN ON THIS SUBJECT: Childhood interstitial lung diseases occur in a variety of clinical contexts and are associated with high morbidity and mortality. Advances in the understanding of disease pathogenesis and use of standardized terminology have facilitated increased case ascertainment. WHAT THIS STUDY ADDS:This study demonstrates that cases of newly described forms of childhood interstitial lung diseases likely occur at all children' s hospitals. With advances in genetic testing and recognition of imaging patterns, a significant portion of cases are identifiable with noninvasive evaluations. abstract OBJECTIVE: Childhood interstitial lung diseases (ILD) occur in a variety of clinical contexts. Advances in the understanding of disease pathogenesis and use of standardized terminology have facilitated increased case ascertainment. However, as all studies have been performed at specialized referral centers, the applicability of these findings to general pulmonary practice has been uncertain. The objective of this study was to determine the historical occurrence of childhood ILD to provide information reflecting general pediatric pulmonary practice patterns. METHODS:Childhood ILD cases seen at Vanderbilt Children' s Hospital from 1994 to 2011 were retrospectively reviewed and classified according to the current pediatric diffuse lung disease histopathologic classification system. RESULTS:A total of 93 cases were identified, of which 91.4% were classifiable. A total of 68.8% (64/93) of subjects underwent lung biopsy in their evaluations. The largest classification categories were disorders related to systemic disease processes (24.7%), disorders of the immunocompromised host (24.7%), and disorders more prevalent in infancy (22.6%). Eight cases of neuroendocrine cell hyperplasia of infancy (NEHI) were identified, including 5 that were previously unrecognized before this review.CONCLUSIONS: Our findings demonstrate the general scope of childhood ILD and that these cases present within a variety of pediatric subspecialties. Retrospective review was valuable in recognizing more recently described forms of childhood ILD. As a significant portion of cases were classifiable based on clinical, genetic, and/or radiographic criteria, we urge greater consideration to noninvasive diagnostic approaches and suggest modification to the current childhood ILD classification scheme to accommodate the increasing number of cases diagnosed without lung biopsy. Pediatrics 2013;132:684-691

Renal leukemic involvement in children can present with a variety of CT imaging findings. Focal renal abnormalities as well as nephromegaly are frequently observed. Most commonly, renal leukemic involvement does not appear to impair renal function.