First measurement of neutrino oscillation parameters using neutrinos and antineutrinos by NOvA

The NOvA experiment has seen a 4.4σ signal of ν[over ¯]_{e} appearance in a 2 GeV ν[over ¯]_{μ} beam at a distance of 810 km. Using 12.33×10^{20} protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ν[over ¯]_{μ}→ν[over ¯]_{e} candidates with a background of 10.3 and 102 ν[over ¯]_{μ}→ν[over ¯]_{μ} candidates. This new antineutrino data are combined with neutrino data to measure the parameters |Δm_{32}^{2}|=2.48_{-0.06}^{+0.11}×10^{-3}  eV^{2}/c^{4} and sin^{2}θ_{23} in the ranges from (0.53-0.60) and (0.45-0.48) in the normal neutrino mass hierarchy. The data exclude most values near δ_{CP}=π/2 for the inverted mass hierarchy by more than 3σ and favor the normal neutrino mass hierarchy by 1.9σ and θ_{23} values in the upper octant by 1.6σ.

Measurement of the Neutrino Mixing Angle θ_{23} in NOvA

This Letter reports new results on muon neutrino disappearance from NOvA, using a 14 kton detector equivalent exposure of 6.05×10^{20} protons on target from the NuMI beam at the Fermi National Accelerator Laboratory. The measurement probes the muon-tau symmetry hypothesis that requires maximal θ_{23} mixing (θ_{23}=π/4). Assuming the normal mass hierarchy, we find Δm_{32}^{2}=(2.67±0.11)×10^{-3}  eV^{2} and sin^{2}θ_{23} at the two statistically degenerate values 0.404_{-0.022}^{+0.030} and 0.624_{-0.030}^{+0.022}, both at the 68% confidence level. Our data disfavor the maximal mixing scenario with 2.6σ significance.

First Measurement of Electron Neutrino Appearance in NOvA

We report results from the first search for ν_{μ}→ν_{e} transitions by the NOvA experiment. In an exposure equivalent to 2.74×10^{20} protons on target in the upgraded NuMI beam at Fermilab, we observe 6 events in the Far Detector, compared to a background expectation of 0.99±0.11(syst) events based on the Near Detector measurement. A secondary analysis observes 11 events with a background of 1.07±0.14(syst). The 3.3σ excess of events observed in the primary analysis disfavors 0.1π<δ_{CP}<0.5π in the inverted mass hierarchy at the 90% C.L.

Strengthening the argument for rapid brain MR imaging: estimation of reduction in lifetime attributable risk of developing fatal cancer in children with shunted hydrocephalus by instituting a rapid brain MR imaging protocol in lieu of Head CT

BACKGROUND AND PURPOSE

Children with shunted hydrocephalus have been undergoing surveillance neuroimaging, generally in the form of head CT, for evaluation of ventricular size. As the life expectancy of these children has improved due to better shunt technology and medical care, risks related to the ionizing radiation incurred during multiple head CT examinations that they are expected to undergo throughout their lifetime have become a concern. The purpose of this study is to estimate the LAR of developing fatal cancer due to head CT for ventricular size assessment in children with shunted hydrocephalus and to assess the impact of instituting a rapid brain MR imaging protocol in reducing radiation exposure.

MATERIALS AND METHODS

Retrospective review of medical records yielded 182 patients who underwent neuroimaging for assessment of ventricular size. Available neuroimaging studies (head CT and rapid brain MR) were counted and annual neuroimaging frequency was calculated. It was assumed that these patients undergo a similar number of neuroimaging studies annually through 20 years of age. A risk estimate was calculated based on the BEIR VII report and effective doses obtained using the International Commission on Radiologic Protection Report 103 organ weighting factors.

RESULTS

The mean annual neuroimaging study frequency was 2.1. Based on the average age of 1.89 years, it was assumed neuroimaging surveillance commences in the second year of life. LAR was calculated assuming that a patient undergoes neuroimaging in the form of head CT at this frequency (2/year) through 20 years of age. Assuming 2 scans are performed per year and the low-dose head CT protocol is used, approximately 1 excess lifetime fatal cancer would be generated per 230 patients; with standard head CT, there would be 1 excess lifetime fatal cancer per 97 patients.

CONCLUSIONS

Children with shunted hydrocephalus are at increased risk of developing fatal cancer if they are to undergo surveillance using head CT. Implementation of a rapid brain MR imaging protocol with no radiation detriment will reduce this risk.

SU-E-I-10: Putting Teeth into Your CT Dosimetry Program: Approaches to Cone- Beam Dental/Maxillofacial CT Dosimetry

PURPOSE

To review and compare different approaches to the problem of dosimetry for limited field-of-view (FOV) cone beam CT devices for dental and maxillofacial applications.

METHODS

The determination of patient doses from specialized, cone-beam CT devices for dental and maxillofacial work requires medical physicists to re-evaluate their dosimetry methods. These devices work in cone-beam geometry, with an axial field dimension on the order of the lengths of the standard head CTDI phantom and pencil ionization chamber. They may also utilize less than 360 degree scans, resulting in asymmetrical radiation distributions. This operating regime is far from that for which conventional CT dosimetry was designed, and alternative approaches must be considered. The alternatives include extensions of conventional CT dosimetry currently used for large axial FOV scanners (e.g. the extended CTDI parameter (CTDIe) for the Toshiba Aquillion One with 160 mm axial FOV) and the new method based on point dosimetry measurements recently formalized in AAPM Report TG-111. Conventional, modified-conventional, and TG-111 dosimetry measurements are used in two CT dose phantoms (adult head and pediatric head) to obtain dose indices for the Planmeca ProMax 3D Max dental CT scanner. Surface dose maps are generated using radiochromic film for correlation with the chamber dosimetry.

RESULTS

Results for the three dosimetry approaches are compared for the specific case of the ProMax 3D Max scanner. Strengths and weaknesses of the three measurement paradigms for this type of application are compared.

CONCLUSIONS

The increasing availability of specialized scanners operating in full cone-beam mode will require the clinical medical physicist to be conversant with extensions to the CT dose index methodology suitable for this equipment.

Studies on the role of 5-HT2C and 5-HT2B receptors in regulating generalised seizure threshold in rodents

The present studies were conducted to investigate the role of 5-HT2C and 5-HT2B receptors in the generation of pentylenetetrazol and electroshock-evoked seizures. The 5-HT2C/2B receptor-preferring agonist 1-(m-chlorophenyl)-piperazine (mCPP; 2.5-7 mg/kg i.p.) weakly elevated seizure threshold in the mouse (but not the rat) electroshock test and also provided appreciable protection against pentylenetetrazol-induced myoclonic and/or tonic seizures in mice and rats, an action that was inhibited by the 5-HT2C/2B receptor antagonist 5-methyl-1-(3-pyridylcarbomoyl)-1,2,3,5-tetrahydropyrrolo[2, 3-f]indole (SB-206553; 10-20 mg/kg p.o.). In contrast, the 5-HT2B receptor agonist 1-[5-(2-thienylmethoxy)-1H-3-indoyl]propan-2-amine hydrochloride (BW-723C86; 3-30 mg/kg s.c.) had no effect on the threshold for generalised seizures in any of the models employed. These results indicate that the observed anticonvulsant effects of mCPP are likely to be mediated by activation of 5-HT2C receptors. However, blockade of these receptors in mice (or rats) by SB-206553 (5-20 mg/kg p.o.) did not result in the reduced seizure threshold characteristic of mutant mice deficient of 5-HT2C receptors, suggesting that in normal adult animals this receptor subtype may usually be subjected to only a low level of 5-hydroxytryptamine tone.

Treatment of articular cartilage defects of the knee with autologous chondrocyte implantation

The treatment of focal full thickness articular defects in the knee has continued to present a challenge, with no traditional treatment method providing consistent acceptable long-term clinical results. Patients with significant chondral defects frequently have persistent joint line pain, swelling, and catching in the knee. In contrast to marrow stimulation treatment techniques, such as abrasion arthroplasty, drilling, or microfracture which populate the defect with pluripotential stem cells, the use of cultured autologous chondrocytes fills the defect with cells of a committed pathway to develop hyaline-like cartilage. This hyaline-like cartilage more closely recreates the wear characteristics and durability of normal hyaline cartilage than the fibrous or fibrocartilage repair tissue formed by pluripotential stem cells. The purpose of this paper is to review the efficacy of available treatment options as well as the basic science rationale, indications, technique, postoperative rehabilitation, and clinical results of using cultured autologous chondrocytes in the treatment of focal full thickness chondral defects of the knee.

An investigation of the mechanism responsible for fluoxetine-induced hypophagia in rats

The effect of fluoxetine on feeding in p-chlorophenylalanine (PCPA) pretreated rats and the nature of its interaction with 5-HT2C receptors have been investigated. Animals that received 3 days PCPA (150 mg/kg i.p.) pretreatment and vehicle on the test day consumed a similar amount as control, saline pretreated animals under the test paradigm used in this study. Fluoxetine (20 and 30 mg/kg p.o.) significantly reduced food intake in PCPA and control pretreated animals to a similar extent, despite an approximately 90% reduction in the levels of brain 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) in the PCPA-pretreated animals. Thus, hypophagia is unlikely to be caused by inhibition of 5-HT reuptake. In the pig choroid plexus in vitro, fluoxetine and norfluoxetine inhibited specific [3H] mesulergine binding with pKI's (+/- S.E.M.) of 6.45 +/- 0.09 (n = 4) and 6.05 +/- 0.05 (n = 3), and slope factors (+/- S.E.M.) of 1.06 +/- 0.14 and 0.99 +/- 0.13, respectively. In slices of piglet choroid plexus fluoxetine (1, 10 and 33 microM) caused a rightward shift in the dose-response curve produced by 5-HT with no effect on the maximal response, and a mean pKB of 5.94 +/- 0.09. Norfluoxetine (10 microM) also produced a rightward shift in the 5-HT dose-response curve with no effect on the maximal response, and a pKB of 6.20. Thus, both compounds acted as surmountable antagonists with no agonist efficacy at 5-HT2C receptors present in choroid plexus. The hypophagic effect of fluoxetine (20 mg/kg p.o.) was also unaffected by the non-specific 5-HT2C receptor antagonist metergoline (2 and 5 mg/kg i.p.). These findings suggest that the hypophagic effect of fluoxetine is not likely to be dependent upon intact brain 5-hydroxytryptaminergic presynaptic function, nor is it mediated by an agonist action at the 5-HT2C receptor, but by an additional, unknown mechanism.

5-HT2 receptor subtypes: a family re-united?

The current classification for 5-HT2 receptors accommodates three subtypes. In addition to the originally defined 5-HT2 receptor, sanctuary is now provided for the structurally related 5-HT1c receptor (now 5-HT2c) and at least one atypical 5-HT receptor subtype. The strong functional union of this family is reflected in the paucity of ligands that will discriminate between its subtypes and prompts some re-evaluation of the activities of compounds which may now be regarded as nonselective for the receptor subtypes in this class. In this article, Gordon Baxter and colleagues examine the pharmacology of both officially recognized and atypical 5-HT2 receptor subtypes. A number of novel selective agents are highlighted, some of which may prove useful for 5-HT2 receptor classification and, ultimately, clarify the mechanistic basis for current and future therapeutic strategies which target this receptor family.

Embryonic fat-cell lineage in Drosophila melanogaster

The Drosophila adipose tissue, or fat body, and the bodywall muscle are two major tissues derived from the mesoderm. Although much is known about the lineage of muscle cells, little is known about the development of the fat body. Using known genes and an enhancer trap (29D), we have begun to trace the lineage of the cells comprising the fat body. The genes Adh (alcohol dehydrogenase) and DCg1 (type IV collagen) code for gene products involved in fat-cell metabolism and therefore serve as terminal fat-cell differentiation markers. The expression of these genes was used to identify the fat body at stage 17 and to identify the start of terminal fat-cell differentiation at stage 15. We found that the steroid-hormone receptor gene, svp (seven-up), was expressed transiently within the fat-cell lineage from stages 12 to 14. We suggest that stage 12 marks the beginning of early fat-cell differentiation and that the svp-positive cells within the mesoderm are early precursor fat cells. To confirm the identity of these cells and to establish the role of svp in the developing fat cell, we examined svp mutant embryos for alterations in the expression of the two terminal fat-cell differentiation markers, Adh and DCg1. Loss of svp function resulted in the loss of Adh transcript and a reduction of DCg1 expression specifically in the fat body. Thus, svp plays a role in fat-body-specific expression of at least two terminal fat-cell differentiation genes. In contrast to svp, we found no evidence that the steroid receptor HNF-4(D) gene was expressed in the fat body nor that it was involved in the development of this tissue. Using an enhancer-trap line (29D), we further traced the fat-cell lineage to nine bilateral clusters of cells within the mesoderm at germ-band extension. We suggest these 29D-positive cells represent the progenitor fat cells. In stage-12 embryos, the 29D-positive cell clusters can be identified within the mesoderm internal to nautilus-expressing cells. These data suggest that the precursor fat cells may be derived from the inner mesoderm, or spanchnopleura. Embryos deficient for the DNA region surrounding the site of the 29D enhancer trap lack most, if not all, of the cells in the fat-cell lineage. These embryos exhibit the loss of svp-positive precursor fat cells and concomitant loss of fat-body-specific expression of Adh and DCg1.(ABSTRACT TRUNCATED AT 400 WORDS)

5-hydroxytryptamine antagonistic effects of ICI 169,369, ICI 170,809 and methysergide in human temporal and cerebral arteries

ICI 169,369 and ICI 170,809 are two chemically novel 5-HT antagonists that have high affinity for the 5-HT2 binding site in rat cortex (Ki 1.79 x 10(-8)M and 6.6 x 10(-10)M, respectively). In human temporal artery preparations ICI 169,369 was shown to cause a progressive rightward shift of the 5-HT-response curve over the range 10(-7)-10(-5)M, while ICI 170,809 in these concentrations shifted the curve to the same degree (no dose dependency). In human cerebral vessels no effect was observed until a high concentration (10(-5)M) was used for either compounds. The mixed 5-HT1/5-HT2 antagonist, methysergide, induced a non parallel rightward shift of the 5-HT-induced concentration-effect curve with a depression of the maximum achievable response in both the temporal and cerebral artery. The mode of effect of ICI 169,369 and ICI 170,809 to block the 5-HT-induced contractions in human temporal vessels resembles that of the pure 5-HT2 antagonist ketanserin, thus suggesting that the two ICI compounds are mainly 5-HT2 antagonists. In high concentrations both ICI 169,369 and ICI 170,809 have vasorelaxant properties, explaining the reduction in maximum 5-HT-induced contraction seen at high antagonist concentrations.

Cystocerebral syndrome. Acute urinary retention presenting as confusion in elderly patients

The diagnosis of acute mental status changes in the elderly patient is often very difficult. Many causes are possible, and there is often little history obtainable. The physical examination occasionally provides the essential clues needed to discover the source of the sudden deterioration. We have recently evaluated four episodes of acute delirium in three elderly patients who presented with no readily apparent cause for these changes. On further evaluation, the patients were found to have marked bladder distention associated with acute urinary retention. None of these patients complained of discomfort, and none had any awareness or recollection of their deterioration. Each patient had rapid resolution of symptoms on bladder decompression. To our knowledge, this "cystocerebral syndrome" has not been previously described, and we suggest that it be considered in the evaluation of acute confusional states in elderly men.

Prevention of ankle sprains

Ankles are sprained when supported on an unstable foundation, while too rididly fixed to the playing surface, or when forced into unnatural positions by extrinsic muscle tightness. The unstable foundation may be the shoe itself, a chuck-hole, or another player's foot. Undue fixation may be by 1-inch mud cleats, baseball spikes, or a modern wrestling mat. When these circumstances occur, heel cord tightness may alter the ankle's response. Thus, prevention of ankle sprains may be by modification of any of these factors.