Subcellular organization of camkii in rat hippocampal pyramidal neurons

Calcium/calmodulin‐dependent protein kinase II (CaMKII) plays a key role in N‐methyl‐D‐aspartate (NMDA) receptor‐dependent long‐term synaptic plasticity; its location is critical for signal transduction, and may provide clues that further elucidate its function. We therefore examined the subcellular localization of CaMKII in CA1 stratum radiatum of adult rat hippocampus, by using immuno‐electron microscopy after chemical fixation. When tissue was fixed quickly, the concentration of CaMKIIα (assessed by pre‐embedding immunogold) was significantly higher in dendritic shafts than in spine heads. However, when tissue was fixed 5 minutes after perfusion with normal saline, the density of labeling decreased in dendritic shaft while increasing in spine heads, implying rapid translocation into the spine during brief perimortem stress. Likewise, in quickly fixed tissue, CaMKII within spine heads was found at comparable concentrations in the “proximal” half (adjacent to the spine neck) and the “distal” half (containing the postsynaptic density [PSD]), whereas after delayed fixation, label density increased in the distal side of the spine head, suggesting that CaMKII within the spine head moves toward the PSD during this interval. To estimate its distribution at the synapse in vivo, we performed postembedding immunogold staining for CaMKII in quick‐fixed tissue, and found that the enzyme did not concentrate primarily within the central matrix of the PSD. Instead, labeling density peaked ～40 nm inside the postsynaptic membrane, at the cytoplasmic fringe of the PSD. Labeling within 25 nm of the postsynaptic membrane concentrated at the lateral edge of the synapse. This lateral “PSD core” pool of CaMKII may play a special role in synaptic plasticity. J. Comp. Neurol. 521:3570‐3583, 2013. © 2013 Wiley Periodicals, Inc.     

Familial pseudomembranous colitis and its relation to lincomycin therapy

Severe pseudomembranous colitis was observed in 3 members of a single family: the father and 2 of his children. 2 of the affected family members received the antibiotic lincomycin prior to the onset of their symptoms. The findings in this family raise the possibility that antibiotic-induced pseudomembranous colitis in some patients may be the result of a pharmacogenetic interaction.Supported by grants from the National Institutes of Health (GM 19258) and from the Upjohn Co. Dr. Brown is an Established Investigator of The American Heart Association. Dr. Goldstein is the recipient of USPHS Research Career Development Award 5 KO4 GM 70277.     

Newborn Screening for SCID in New York State: Experience from the First Two Years

Purpose

To describe the process and assess outcomes for the first 2 years of newborn screening for severe combined immunodeficiency (SCID NBS) in New York State (NYS).

Methods

The NYS algorithm utilizes a first-tier molecular screen for TRECs (T-cell receptor excision circles), the absence of which is indicative of increased risk of immunodeficiency.

Results

During the first 2 years, 485,912 infants were screened for SCID. Repeat specimens were requested from 561 premature and 746 non-premature infants with low or borderline TRECs. A total of 531 infants were referred for diagnostic evaluation leading to identification of 10 infants with SCID and 87 with a clinically significant non-SCID abnormality based on flow cytometry or CBC results (positive predictive value 20.3 %). Nine infants were diagnosed with typical SCID and one with leaky SCID. SCID diagnoses included two patients with adenosine deaminase deficiency, three patients with typical and one with leaky IL2RG-related SCID, one patient with IL7Rα-related SCID, and three cases of typical SCID, etiology unknown. TRECs were undetectable in eight of the nine babies with typical SCID. Infants with other non-SCID conditions included 27 patients with a syndrome that included T-cell impairment, 18 of which had DiGeorge syndrome. Seventeen infants had T-cell impairment secondary to another clinically significant condition, and 13 were classified as ‘other’. Among 30 infants classified as idiopathic T-cell lymphopenia, 11 have since resolved, and the remainder continues to be followed. One infant with undetectable TRECs had normal follow-up studies. Molecular studies revealed the presence of two changes in the infant’s DNA.

Conclusions

Overall, ten infants with SCID were identified during the first 2 years of screening in NYS, yielding an incidence of approximately 1 in 48,500 live births, which is consistent with the incidence observed by other states screening for SCID. The incidence of any clinically significant laboratory abnormality was approximately 1 in 5,000; both estimates are higher than estimates prior to the onset of newborn screening for SCID. Improvements to the NYS algorithm included the addition of a borderline category that reduced the proportion of infants referred for flow cytometric analysis, without decreasing sensitivity. We identified a large number of infants with abnormal TRECs and subsequent idiopathic T-cell lymphopenia. Long-term follow-up studies are needed to determine the prognosis and optimal treatment for this group of patients, some of whom may present with previously unrecognized, transient lymphopenia of infancy.