Baseline brain function in the preadolescents of the ABCD Study.

The Adolescent Brain Cognitive Development (ABCD) Study® is a 10-year longitudinal study of children recruited at ages 9 and 10. A battery of neuroimaging tasks are administered biennially to track neurodevelopment and identify individual differences in brain function. This study reports activation patterns from functional MRI (fMRI) tasks completed at baseline, which were designed to measure cognitive impulse control with a stop signal task (SST; N = 5,547), reward anticipation and receipt with a monetary incentive delay (MID) task (N = 6,657) and working memory and emotion reactivity with an emotional N-back (EN-back) task (N = 6,009). Further, we report the spatial reproducibility of activation patterns by assessing between-group vertex/voxelwise correlations of blood oxygen level-dependent (BOLD) activation. Analyses reveal robust brain activations that are consistent with the published literature, vary across fMRI tasks/contrasts and slightly correlate with individual behavioral performance on the tasks. These results establish the preadolescent brain function baseline, guide interpretation of cross-sectional analyses and will enable the investigation of longitudinal changes during adolescent development.

Mitochondrial participation in the intracellular Ca2+ network.

Calcium can activate mitochondrial metabolism, and the possibility that mitochondrial Ca2+ uptake and extrusion modulate free cytosolic [Ca2+] (Cac) now has renewed interest. We use whole-cell and perforated patch clamp methods together with rapid local perfusion to introduce probes and inhibitors to rat chromaffin cells, to evoke Ca2+ entry, and to monitor Ca2+-activated currents that report near-surface [Ca2+]. We show that rapid recovery from elevations of Cac requires both the mitochondrial Ca2+ uniporter and the mitochondrial energization that drives Ca2+ uptake through it. Applying imaging and single-cell photometric methods, we find that the probe rhod-2 selectively localizes to mitochondria and uses its responses to quantify mitochondrial free [Ca2+] (Cam). The indicated resting Cam of 100-200 nM is similar to the resting Cac reported by the probes indo-1 and Calcium Green, or its dextran conjugate in the cytoplasm. Simultaneous monitoring of Cam and Cac at high temporal resolution shows that, although Cam increases less than Cac, mitochondrial sequestration of Ca2+ is fast and has high capacity. We find that mitochondrial Ca2+ uptake limits the rise and underlies the rapid decay of Cac excursions produced by Ca2+ entry or by mobilization of reticular stores. We also find that subsequent export of Ca2+ from mitochondria, seen as declining Cam, prolongs complete Cac recovery and that suppressing export of Ca2+, by inhibition of the mitochondrial Na+/ Ca2+ exchanger, reversibly hastens final recovery of Cac. We conclude that mitochondria are active participants in cellular Ca2+ signaling, whose unique role is determined by their ability to rapidly accumulate and then release large quantities of Ca2+.

Dominant role of mitochondria in clearance of large Ca2+ loads from rat adrenal chromaffin cells.

Cytosolic Ca2+ (Ca2+c) clearance from adrenal chromaffin cells was studied by whole-cell patch clamp and indo-1 Ca2+ photometry after influx of Ca2+ through voltage-dependent Ca2+ channels. We isolated the rates of Ca2+c clearance by several mechanisms using combinations of the following agents (with their expected targets): Li+ or TEA substituted for Na+ (Na(+)-Ca2+ exchange), 1 mM La3+ applied after the depolarization (Na(+)-Ca2+ exchange and plasma membrane Ca(2+)-ATPase), 1 microM thapsigargin (pumping into reticular stores), and 2 microM carbonyl cyanide m-chlorophenylhydrazone (uptake into mitochondria). Remarkably, whenever [Ca2+]c rose above approximately 500 nM, Ca2+c clearance by mitochondria exceeded clearance by either Na(+)-Ca2+ exchange or the Ca2+ pumps of the plasma and reticular membranes. As [Ca2+]c fell again, Ca2+ reemerged from mitochondria, prolonging the final return to basal levels.

Rapid screening of a large insert BAC library for specific 16S rRNA genes using TRFLP.

It is widely believed that the vast majority of microbes in the environment have-yet-to-be cultured using standard techniques. Bulk DNA from microbial communities is therefore often cloned into large insert vectors (e.g. bacterial artificial chromosomes [BAC] or cosmids) in order to study the genetic properties of these as yet (un)-cultured bacteria. In a typical BAC experiment, tens of thousands of clones are generated with only a small fraction of colonies containing the target(s) of interest. Efficient screening methodologies are therefore needed to allow targeted clone isolation. In this paper, we describe a rapid, inexpensive protocol that allows for the identification of specific 16S ribosomal RNA genes in a metagenomic library arrayed into 384-well microtiter plates. The rapid screening protocol employs Terminal Restriction Fragment Length Polymorphism (TRFLP) analysis to identify wells containing specific T-RF peaks. A nested approach using multiplexed samples of 384, 48, 8, and single colony analysis is described and applied in order to survey a BAC library generated from a marine microbial community off the coast of New Jersey. Screening revealed a total of 50 different 16 rRNA genes within the BAC library. Overall, the multiplexing format provided a simple, cost effective methodology for detecting clones bearing a target gene of interest in a large clone library. However, the limitations of screening BAC libraries using PCR methodologies and recommendations for improved screening efficiency using this approach are also discussed.

Fibrinolytic properties of lysine-derivatized polyethylene in contact with flowing whole blood (Chandler loop model).

This article reports on the concept of a fibrinolytic surface based on the preferential adsorption of endogenous plasminogen from blood. Data are presented indicating that such a surface, when pretreated with tissue-type plasminogen activator (tPA), is able to dissolve nascent thrombus generated in contact with flowing whole blood. Polyethylene (PE) surfaces were modified by attaching a lysine-containing polymer using photochemical methods as reported previously (McClung et al., J Biomed Mater Res 2000;49:409-414). The lysine residues were bound chemically to the polymer via the alpha-amino groups leaving the epsilon-amino groups free (epsilon-Lys surface). Control surfaces were (a) unmodified PE, (b) PE modified with the coating polymer containing no lysine, and (c) PE modified with the polymer containing lysine bound via the epsilon-amino group. The materials in tubing form were evaluated in contact with nonanticoagulated flowing human whole blood in a modified Chandler Loop experiment. They were first treated with tPA to allow activation of adsorbed plasminogen to plasmin. It was found that thrombus formation was initiated within 15-25 min (depending on donor blood) on all surfaces, as indicated by the formation of platelet aggregates. On the controls (including the lysine-containing material in which the epsilon-amino group was used in the binding reaction) thrombogenesis continued till the tubing was occluded and blood flow ceased. On the epsilon-Lys surface, thrombogenesis was interrupted at various stages depending on the donor blood; in all cases any thrombus generated was dissolved within minutes. It was shown that thrombolysis was due to the fibrinolytic action of plasmin generated at the surface and not to plasmin formed by traces of tPA released into the blood. This work provides further evidence of the efficacy of this approach to the development of a fibrinolytic surface.

Mitochondrial oversight of cellular Ca2+ signaling.

Mitochondria, the metabolic powerhouses of the cell, can sequester and release large amounts of Ca2+. This import and export of Ca2+ helps to adjust energy production to cellular needs. Recent advances show that mitochondrial Ca2+ fluxes play a major role in normal Ca2+ signaling.

Role of cellular RNA polymerases in virus-induced leukemogenesis.

Friend murine leukemia virus induces splenic enlargement and an increase in RNA polymerase activity of spleen nuclei. Actinomycin D, administered at 60 mug/kg body weight/day prevents the development os splenomegaly and the elevation of polymerase activity following infection, but it has only a slight effect on the production of virus in spleen tissue. Thus, the alteration of RNA synthesis is not a result of virus proliferation, but instead may be a manifestation of leukemic erythropoiesis. Normal erythropoiesis, stimulated by erythropoietin administration, produces a similar but transient increase in RNA polymerase activity in spleen nuclei. Erythropoietin administered before, but not after, Friend virus infection results in an enhancement of RNA polymerase activity, as measured 9 days after inoculation. This effect is most simply explained by assuming that there is a common target cell pool for both erythropoietin and Friend virus, and that this pool becomes refractory to the influence of the hormone as a result of the leukemic process.

Controlled trial of thyrotropin releasing hormone in amyotrophic lateral sclerosis.

A double-blind controlled trial of thyrotropin releasing hormone (TRH) 150 mg IM daily in 30 patients with amyotrophic lateral sclerosis is reported. The drug/placebo was administered for 2 months, followed by a 2-month "wash-out". Evaluation of strength, functional ability, and respiratory functions was performed. A temporary increase in the strength of some muscles was detected following the administration of TRH, but no change in functional performance was noted. Neither the patients nor the investigators believed the effects were of any marked clinical significance. The course of the illness was not altered.

Abdominoscrotal hydrocele--cause of abdominal mass in children.

Abdominoscrotal hydrocele is relatively uncommon in adults and rare in children. The case presented typifies the classic features of the clinical presentation and the satisfactory response to conservative surgical therapy.

T-cell receptor variable beta genes show differential expression in CD4 and CD8 T cells.

Studies in transgenic and inbred strains of mice have shown that the critical molecular interactions controlling positive selection involve major histocompatibility complex (MHC), T-cell receptor (TCR), and CD4 or CD8 coreceptor molecules. Correlations have been established between MHC gene products and the percentage of CD4 or CD8 T cells that express specific variable (V) beta-gene products as part of the alpha beta heterodimer. These studies have important implications regarding potential mechanisms of HLA-linked autoimmune diseases in humans. If similar interactions are required for positive selection in humans, one would predict that the TCR repertoire expressed by mature, peripheral blood CD4 and CD8 T cells would vary. To test this hypothesis the expression of specific TCR V beta-region genes by CD4 and CD8 T cells from healthy individuals was compared using both triple-color flow cytometry and polymerase chain reaction based experimental approaches. The results show that the TCR repertoire does vary as a function of CD4 and CD8 T-cell subsets. Among unrelated individuals certain V beta genes were consistently overrepresented in the CD4 population (V beta-5.1, -6.7a, and -18); some were skewed to the CD8 population (V beta-14) while others showed variable patterns (V beta-12 and -17). Deletion of entire V beta gene families was not observed suggesting that this is a rare event in humans. Attempts to correlate the expressed TCR repertoire in humans with HLA alleles will require consideration of these differences in expression as a function of subset.

Neuronal apoptosis after CNS injury: the roles of glutamate and calcium.

While a role has been well established for excitotoxic necrosis in the pathogenesis of traumatic or ischemic damage to the CNS, accumulating evidence now suggests that apoptosis may also be a prominent contributor. In this review we focus on the role of glutamate and attendant intracellular calcium influx in triggering or modifying excitotoxic necrosis and apoptosis, raising the possibility that calcium influx may affect these two death pathways in opposite directions. Incorporating consideration of both pathways will probably be needed to develop the most effective neuroprotective treatments for CNS injury.

Use of intraoperative ultrasonography to localize a hepatic abscess.

Intraoperative real-time ultrasonography can be a valuable tool for a surgeon. In a patient with hepatic abscesses, intraoperative ultrasonography assisted in the localization of an abscess cavity situated deep in the parenchyma of an enlarged liver, allowing surgical drainage.

The locomotor effects of a putative dopamine D3 receptor agonist in developing rats.

Dopamine receptors have been categorized into subfamilies D1 and D2, each with separate roles in dopamine-mediated behaviors. Of the D2 subfamily, the dopamine D3 receptor has been cloned, but the behavioral effects of selectively stimulating the D3 receptor are largely unknown. The purpose of this study was to quantify the locomotor responses of developing rats to the putative dopamine D3 receptor agonist, 7-hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OH-DPAT). One of three doses of 7-OH-DPAT (0.01, 0.10, 1.00 mg/kg) or saline was injected subcutaneously into rats at the age of 10,20,30, or 60 days. Five minutes after the injection, rats were placed in automated activity monitors which recorded locomotor behavior at 5 min intervals for 2 h. The high dose of 7-OH-DPAT increased locomotor activity in rats of all ages. The medium and low doses increased activity in 10- and 20-day-old rats but not in 30- or 60-day-old rats. The level of drug-induced activation peaked at 20 days of age. In 30- and 60-day-old rats, but not 10- and 20-day-old rats, a period of locomotor suppression preceded the activation in response to the high dose of 7-OH-DPAT. In rats aged 20 days and older, the middle and low doses decreased locomotion early in the test session, but activation did not ensue. This dose-response pattern across ontogeny closely resembles that induced by quinpirole, an agonist at the dopamine D2 receptor subfamily.

Intracranial hemorrhage in premature infants: sonographic-pathologic correlation.

Spontaneous intracranial hemorrhage is the most common central nervous system abnormality in premature infants. In this report the cranial sonographic and pathologic findings of 25 autopsied premature infants are correlated. The presence and size of subependymal, intraventricular, and intraparenchymal hemorrhage were well documented by sonography. Cerebellar, choroid plexus, and cortical hemorrhage, though less frequent, were also recognized. There was good correlation as to the presence and degree of hydrocephalus. Prominent subarachnoid spaces on sonography correlated poorly with subarachnoid hemorrhage at autopsy and may be a normal variant in the premature infant. Anoxic brain damage was not diagnosed early by sonography unless associated with hemorrhage, but diffuse brain atrophy with hydrocephalus exvacuo was detected by sonography.

Ultrasonography and computed tomography in the evaluation of the acutely ill pediatric patient.

The use of diagnostic ultrasonography and CT in the investigation of the acutely ill pediatric patient has been steadily increasing because of the relative noninvasiveness of these imaging modalities and because of improvements in resolving capabilities and scanning speed of the latest equipment. In the examination of the pediatric patient, special emphasis must be given to immobilization, sedation, or both in those children too young or too ill to cooperate. Close monitoring and observation of the child throughout sedation is important and requires special personnel and equipment. The usual indications are the search for an abscess or occult infection, trauma, and acute renal failure. Because ultrasonography uses nonionizing radiation and is less expensive, it is usually the initial modality of choice for evaluating the pediatric patient. CT is reserved for situations in which greater anatomic detail and lack of compromise by the presence of bowel gas or bone are necessary. These situations include multiple abscess collections, particularly interloop abdominal abscesses, mediastinal masses and collections obscured by overlying lung, osteomyelitis, older patients with meningomyelocele and with spinal deformity when evaluating the urinary tract, and major multiorgan abdominal trauma.

Interactions of fibrinolytic system proteins with lysine-containing surfaces.

Studies on the interactions of tissue plasminogen activator (tPA) and plasminogen with polyurethane surfaces containing epsilon-lysine moieties (epsilon-amino group free) are reported. These surfaces are considered to have the potential to dissolve nascent clots that may be formed on them. For adsorption from both single protein solutions and plasma, the surfaces were found to have a high capacity for tPA as well as plasminogen. A significant fraction of preadsorbed tPA was displaced from the epsilon-lysine surfaces upon contact with plasma. These surfaces, when preadsorbed with tPA and then incubated with plasma, were able to dissolve incipient clots formed around them. However, the clot-dissolving capacity diminished as the time of plasma incubation increased, presumably due to loss of tPA. It was also shown that in plasma, preadsorbed tPA is displaced from these surfaces largely by plasminogen, which thus appears to have a greater binding affinity than tPA for the epsilon-lysine moieties. Finally, it was found that in plasma, the epsilon-lysine surfaces interact with plasminogen in a dynamic manner, and that about 70% of the bound plasminogen is exchanging continuously with plasminogen in the plasma.

Effects of imipramine, chlorimipramine, and fluoxetine on cataplexy in dogs.

Four narcoleptic dogs with cataplexy were given trials with the serotonin uptake blockers imipramine and chlorimipramine (known to be effective in treating cataplexy in humans). An even more selective serotonin uptake blocker, fluoxetine, was also tested. Injections of placebo, test compound, and placebo were given respectively on 3 successive days. Anticataplectic effects were measured approximately 30 min, 3 hr, and 6 hr postinjection by recording elapsed time and number of cataplectic episodes during the dogs' attempts to eat ten pieces of a desired food presented in a standard fashion. Imipramine (1 mg/kg) and fluoxetine (1.5 and 3.0 mg/kg)significantly improved performance, while chlorimipramine (0.5-5 mg/kg) had no clear effect. Data were not totally consistent with the notion that serotonin uptake blockers improve cataplexy in dogs, since chlorimipramine was not effective in these animals.

Quantification of intravenous contrast-enhanced Doppler power spectrum in the rabbit carotid artery.

In vivo evaluation of Doppler contrast agent (DCA) enhancement has been principally qualitative. To quantitate the enhancement of the Doppler signal by perflubron emulsion, an investigational DCA, the audio-Doppler signal from the rabbit carotid artery was recorded during 0.5-ml/kg incremental doses to a total dose of 2.5 ml/kg. A representation of the recorded signal intensity, the Doppler power spectrum (DPS), was determined using a personal computer and commercially available software package. The dose related enhancement from perflubron emulsion was linear (r = 0.986, p = 0.0124) with a 710% (8.5 dB) overall enhancement at 2.5 ml/kg (p = 0.0001). Significant differences in enhancement could be detected with doses as low as 1.0 ml/kg and compared favorably with observer assessment of dose-related enhancement. This relatively simple method of computer analysis can quantify in vivo Doppler signal intensity and enhancement by perflubron emulsion and may enable quantitative comparisons between different DCAs.

Comparison of color Doppler sonography and radionuclide imaging in different degrees of torsion in rabbit testes.

RATIONALE AND OBJECTIVES: We compared color Doppler sonography and radionuclide imaging in an animal model of variable torsion of the testes. METHODS: The testes of 19 rabbits with unilateral 0 degree (nontorsion), 180 degrees, 360 degrees, or 540 degrees torsion and contralateral nontorsion were evaluated by sonography serially over 24 hr. Color Doppler sonography and radionuclide imaging at 24 hr were compared and correlated with pathology in a subset of testes. RESULTS: Nontorsion (n = 16 testes) and 540 degrees torsion (n = 7 testes) were always correctly diagnosed at 24 hr by color Doppler sonography and radionuclide imaging. Torsion at 180 degrees (n = 2) was indistinguishable from nontorsion. With 360 degrees torsion (n = 6 testes), four testes had reduced or absent flow with color Doppler sonography, whereas only one testis was abnormal with radionuclide imaging. CONCLUSION: Nontorsion and extreme torsion of rabbit testes are well documented by radionuclide imaging and color Doppler sonography. Torsion at 360 degrees can result in variable flow alterations that are better detected by color Doppler sonography than by radionuclide imaging.

Doppler contrast sonography for detecting reduced perfusion in experimental ischemia of prepubertal rabbit testes.

RATIONALE AND OBJECTIVES: We examined whether the intravenous (IV) Doppler ultrasound contrast agent SHU 508 would improve the detection of reduced perfusion of rabbit testes when normal flow was otherwise difficult to detect. METHODS: Seventeen anesthetized prepubertal rabbits underwent random unilateral spermatic cord ligation and a contralateral sham operation. Immediate, blinded, and systematic color Doppler examination of each pair of testes was recorded before and after IV administration of 1 ml (300 mg) SHU 508, a gas-containing microparticle. Recorded examinations were reviewed by two pediatric radiologists who were unaware of experimental conditions and who graded intratesticular flow. RESULTS: For 34 pairs of observations (17 animals x 2 observers), intratesticular flow was absent in the sham-operated testes in 18 precontrast and two postcontrast images. The false-positive rate in this group decreased from 53% to 6%. This improvement in the detection of normal blood flow was statistically significant. The absence of flow in the ischemic testis was not significantly different before or after contrast agent administration. CONCLUSION: IV SHU 508 enhances color Doppler ultrasound detection of flow not otherwise evident in prepubertal rabbit testes. Doppler ultrasound contrast agents may be used in a setting of suspected torsion when routine Doppler sonography is indeterminate.