Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector

Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon neutrinos. This search yielded no excess events above those expected from background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux measured at the earth. For an assumed E-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E2Phi(E)=8.4 x 10(-7) cm(-2) s(-1) sr(-1) GeV (for a predominant neutrino energy range 6-1000 TeV), which is the most restrictive bound placed by any neutrino detector. Some specific predicted model spectra are excluded. Interpreting these limits in terms of the flux from a cosmological distributions of sources requires the incorporation of neutrino oscillations, typically weakening the limits by a factor of 2.

The association of age and semen quality in healthy men

BACKGROUND

Although the effect of maternal age on fertility is well known, it is unclear whether paternal age also affects fertility. This cross-sectional study sought to characterize the association between age and semen quality, a well-known proxy of fertility status.

METHODS

A convenience sample of 97 non-smoking men (aged 22-80 years) without known fertility problems was recruited from a national government laboratory. The men provided semen samples and information relating to lifestyle, diet, medical and occupational details. Semen volume (ml), sperm concentration (x10(6)/ml), total sperm count (x10(6)), motility (%), progressive motility (%) and total progressively motile sperm count (x10(6)) were measured.

RESULTS

After adjusting for covariates, semen volume decreased by 0.03 ml per year of age (95% CI: -0.05, -0.01); motility decreased by 0.7% per year (95% CI: -0.92, -0.43); progressive motility decreased by 3.1% per year (95% CI: -4.5, -1.6); and total progressively motile sperm count decreased by 4.7% per year (95% CI: -7.2, -2.2). There was a suggested decrease in sperm concentration and count. The proportion of men with abnormal volume, concentration and motility was significantly increased across the age decades.

CONCLUSIONS

In a convenience sample of healthy men from a non-clinical setting, semen volume and sperm motility decreased continuously between 22-80 years of age, with no evidence of a threshold.

Evaluation of high fidelity patient simulator in assessment of performance of anaesthetists

BACKGROUND

There is increasing emphasis on performance-based assessment of clinical competence. The High Fidelity Patient Simulator (HPS) may be useful for assessment of clinical practice in anaesthesia, but needs formal evaluation of validity, reliability, feasibility and effect on learning. We set out to assess the reliability of a global rating scale for scoring simulator performance in crisis management.

METHODS

Using a global rating scale, three judges independently rated videotapes of anaesthetists in simulated crises in the operating theatre. Five anaesthetists then independently rated subsets of these videotapes.

RESULTS

There was good agreement between raters for medical management, behavioural attributes and overall performance. Agreement was high for both the initial judges and the five additional raters.

CONCLUSIONS

Using a global scale to assess simulator performance, we found good inter-rater reliability for scoring performance in a crisis. We estimate that two judges should provide a reliable assessment. High fidelity simulation should be studied further for assessing clinical performance.

Isolation and molecular characterization of Musca domestica delta-9 desaturase sequences

We have isolated fatty acyl-CoA desaturase cDNA (Mdomd9) and genomic sequences from the housefly, Musca domestica. Two approximately 1.66 kb cDNAs were recovered. They had identical coding regions and 3' untranslated regions (UTRs), but differed in their 5' UTRs. The open reading frame encodes a 380 amino acid (aa) protein with 82% identity to Drosophila melanogaster desat1, and significant (> 50%) identity with other insect delta-9 desaturases. Functional analyses in a yeast expression system confirmed the cDNA encodes a delta9 desaturase. Northern analysis indicated two transcripts of 1.7 and 2.9 kb that hybridized specifically to the open reading frame. PCR amplification of genomic templates revealed three intron sites that are conserved among other insect species. Southern analysis of genomic DNA indicated at least two desaturase gene copies per haploid genome. There is a high degree of polymorphism, most of which appears to be due to variable intron sequences; curiously, individual flies had varying morphs of intron II and intron III. Together, the data suggest that there are more delta9 desaturase alleles within the population studied than there are loci within the genome, and support other studies suggesting that insect fatty acyl-CoA desaturases are a dynamically evolving gene family.

Reduced lung function both before bronchiolitis and at 11 years

BACKGROUND AND AIMS

We have previously shown an association between reduced premorbid lung function (V'maxFRC) and bronchiolitis. We hypothesised that individuals with bronchiolitis will go on to have reduced lung function and increased respiratory symptoms in childhood.

METHODS

V'maxFRC was measured at 1 month of age; individuals with bronchiolitis were prospectively identified. Annual symptom questionnaires were completed from 3 to 6 years. At 11 years of age, children underwent an assessment including questionnaire, lung function, airway response to histamine (AR), and skin prick testing.

RESULTS

Eighteen individuals with bronchiolitis were ascertained from 253 cohort members. Children with bronchiolitis had increased viral induced wheeze at 3 (OR 5.8, 95% CI 1.4 to 25.2; n = 103) and 5 years (OR 5.3, 95% CI 1.1 to 25.5; n = 101). At 11 years of age, 194 children were assessed including 16 with past bronchiolitis. These 16 individuals had reduced mean z scores for % V'maxFRC compared with other children (-0.56 and 0.06 respectively) and mean z scores for % FEF(25-75) at 11 years (-0.53 and 0.06 respectively). At 11 years, FEV(1), FVC PEF, AR, atopy, wheeze, and diagnosed asthma were not different between groups.

CONCLUSIONS

Reduced lung function is present before and after bronchiolitis; the level of reduction is comparable. The mechanism for wheeze and reduced lung function after bronchiolitis appears to be related to premorbid lung function and not bronchiolitis per se.

Randomised controlled trial of short bursts of a potent topical corticosteroid versus prolonged use of a mild preparation for children with mild or moderate atopic eczema

OBJECTIVE

To determine whether a three day burst of a potent corticosteroid is more effective than a mild preparation used for seven days in children with mild or moderate atopic eczema.

DESIGN

Randomised, double blind, parallel group study of 18 weeks' duration.

SETTING

13 general practices and a teaching hospital in the Nottingham area.

PARTICIPANTS

174 children with mild or moderate atopic eczema recruited from general practices and 33 from a hospital outpatient clinic.

INTERVENTIONS

0.1% betamethasone valerate applied for three days followed by the base ointment for four days versus 1% hydrocortisone applied for seven days.

MAIN OUTCOME MEASURES

Primary outcomes were total number of scratch-free days and number of relapses. Secondary outcomes were median duration of relapses, number of undisturbed nights, disease severity (six area, six sign atopic dermatitis severity scale), scores on two quality of life measures (children's life quality index and dermatitis family impact questionnaire), and number of patients in whom treatment failed in each arm.

RESULTS

No differences were found between the two groups. This was consistent for all outcomes. The median number of scratch-free days was 118.0 for the mild group and 117.5 for the potent group (difference 0.5, 95% confidence interval -2.0 to 4.0, P=0.53). The median number of relapses for both groups was 1.0. Both groups showed clinically important improvements in disease severity and quality of life compared with baseline.

CONCLUSION

A short burst of a potent topical corticosteroid is just as effective as prolonged use of a milder preparation for controlling mild or moderate atopic eczema in children.

The Localio approach: a technical note for a large sacral chordoma

Whenvever possible, radical resection of retrorectal tumours should be performed.(1) We describe the Localio technique (abdominosacral approach) in a case of a large malignant sacral chordoma. We emphasise the necessity to perform such an approach to achieve a radical resection for these tumours which have little chemosensitivity and minimal radiosensitivity. We highlight clinical features which suggest the presence of a spinal tumour and reiterate the absolute importance of rectal examination.

Maintaining standard scales of reproduction in patient photography using digital cameras

The use of standard representational photography of patients and the control of the variables in that process, have long been the factor that separates the professional medical photographer from the DIY enthusiast. The published recommendations on how standard representational photography can be set up and maintained have been based on the use of 35-mm film cameras. The common use of digital cameras in departments of medical illustration have brought with them new problems, one of which is the variability of size of the CCD fitted to these cameras. As CCDs are, at the time of writing, smaller than the 35-mm frame size, established protocols need to be changed. This problem can be compounded if a department uses more than one type of camera, each with a different CCD. This paper sets out a method for calculating and calibrating the new scales of reproduction required for digital cameras.

Failure of antiretroviral therapy to control Varicella zoster retinitis

The term necrotizing herpetic retinopathies encompasses a spectrum of diseases which includes cytomegalovirus (CMV) retinitis, acute retinal necrosis (ARN) and Varicella zoster retinitis (VZR). Varicella zoster retinitis is a rapidly progressive, necrotizing condition most commonly reported in patients with AIDS. A case of vitreous biopsy-proven VZR is reported in a patient with AIDS that progressed despite immune recovery on highly active antiretroviral therapy (HAART) to a viral load < 50 copies/mL and a CD4 count of 230 cells/microL. This is in contrast to CMV retinitis in which maintenance therapy appears unnecessary once the CD4 count rises and the viral load falls on HAART. Patients with VZR and AIDS should therefore be monitored for reactivation of retinal disease despite HAART-induced remission.

The thymus gland

This article reviews the embryology, physiology, and pathophysiology of the thymus. The anatomy of this lymphoid organ, the significance of the presence or absence of the thymus radiographically, and the role of the thymus in immunity are also reviewed. Finally, the pathologic presentation of thymic hypoplasia (DiGeorge syndrome) is discussed. Despite advances in modern science, little was known about the thymus, one of the body's key organs in the immune system, until 1961, when Dr. Jacques Miller performed thymectomies in mice. Then it became evident that the thymus played a key role in the body's defense against infection. Since that time, researchers have continued to examine the role of the thymus from fetal life through adulthood.

A senior elective: promoting health in underserved communities

OBJECTIVES

A fourth-year service-learning elective was developed to teach medical students about the social, economic, and culturalfactors that affect health and health-seeking behavior

DESCRIPTION

The elective provides students with didactic material and educational experiences in public housing sites in the community. Students work closely with community members to implement a community health care intervention.

EVALUATION

Students respond to 10 reflection questions that assess their understanding of the important community factors that affect health.

CONCLUSIONS

Reflection responses demonstrate that the course has challenged assumptions, dispelled stereotypes, and enhanced awareness of the role of socialfactors in maintaining health.

Immunopathology of the noninfectious posterior and intermediate uveitides

The posterior and intermediate uveitides share an underlying immune etiology; however, they can be clinically and immunopathologically distinguished. Although the initiating stimuli for posterior and intermediate uveities are not known, it is believed that an exogenous agent (such as a bacterium or a virus) or an endogenous molecule may induce disease. In either case, T-helper lymphocytes in conjunction with human leukocyte antigens are likely to be involved. This review examines the epidemiology, histology, immunopathology, and theories of pathogenesis of several posterior and intermediate uveitides, including sympathetic ophthalmia, Vogt-Koyanagi-Harada syndrome, Behçet's disease, sarcoidosis, intermediate uveitis, white dot syndromes, and birdshot retinochoroidopathy.

Isolated sonographic markers for detection of fetal Down syndrome in the second trimester of pregnancy

OBJECTIVE

To determine whether sonographic "markers" are associated with fetal Down syndrome during the second trimester and to estimate the degree of risk of individual markers using likelihood ratios.

METHODS

Second-trimester (14-20 weeks) sonographic findings in 186 fetuses with trisomy 21 were compared with a control group of 8728 consecutive control fetuses. Six markers were evaluated: nuchal thickening, hyperechoic bowel, shortened femur, shortened humerus, echogenic intracardiac focus, and renal pyelectasis.

RESULTS

Major or structural abnormalities were observed in 31 fetuses with trisomy 21 (16.7%) and 53 control fetuses (0.6%) (P< .001). Some type of sonographic finding (major abnormality, minor marker, or both) was observed in 68.8% of fetuses with trisomy 21 compared with 13.6% of control fetuses (P < .001). An isolated minor or "soft" marker was the only sonographic finding in 42 (22.6%) of 186 fetuses with trisomy 21 compared with 987 (11.3%) of 8728 control fetuses (P < .001). Nuchal thickening (P < .001; likelihood ratio, 11) and hyperechoic bowel (P < .001; likelihood ratio, 6.7) showed the strongest association with trisomy 21 as isolated markers, followed by shortened humerus (likelihood ratio, 5.1), echogenic intracardiac focus (likelihood ratio, 1.8), shortened femur (likelihood ratio, 1.5), and pyelectasis (likelihood ratio, 1.5). Echogenic intracardiac focus was the single most common isolated marker in both affected fetuses (7.1%) and control fetuses (3.9%) but carried a low risk (P= .046; likelihood ratio, 1.8).

CONCLUSIONS

A single soft marker is commonly encountered during the second trimester among fetuses with trisomy 21. The risk of fetal Down syndrome, reflected by likelihood ratios, was determined for 6 individual markers. This information can be combined with the a priori risk to estimate the individual patient risk for fetal Down syndrome.

Phosphatidylinositol 3 kinase contributes to the transformation of hematopoietic cells by the D816V c-Kit mutant

Stem cell factor (SCF) binds the receptor tyrosine kinase c-Kit and is critical for normal hematopoiesis. Substitution of valine for aspartic acid 816 (D816V) constitutively actives human c-Kit, and this mutation is found in patients with mastocytosis, leukemia, and germ cell tumors. Immortalized murine progenitor cells (MIHCs) transduced with wild-type c-Kit proliferate in response to SCF, whereas cells expressing D816V c-Kit (MIHC-D816V) are factor-independent and tumorigenic. However, the mechanisms mediating transformation by D816V c-Kit are unknown. The objective of this study was to identify signaling components that contribute to D816V c-Kit-mediated transformation. SCF stimulates association of p85PI3K with phosphorylated tyrosine 721 of wild-type c-Kit. Phosphatidylinositol 3 kinase (PI3K) subsequently contributes to the activation of Akt and Jnks. In contrast, these studies demonstrated that the D816V c-Kit mutant was constitutively associated with phosphorylated p85PI3K, and, downstream of PI3K, Jnk 1 and Jnk 2 were activated but Akt was not. Interestingly, Erks 1 and 2 were not constitutively activated by D816V c-Kit. Thus, D816V c-Kit maintains the activity of PI3K but not of all signaling pathways activated by wild-type c-Kit. Further, all pathways downstream of PI3K are not constitutively active in MIHC-D816V cells. Studies with a PI3K inhibitor and D816V/Y721F c-Kit, a mutant incapable of recruiting PI3K, indicate that constitutive activation of PI3K through direct recruitment by D816V c-Kit plays a role in factor-independent growth of MIHC and is critical for tumorigenicity.

Bronchoconstrictor reactivity to NKA in allergic dogs: a comparison to histamine and methacholine

Airway hyperresponsiveness to neurokinin A (NKA) occurs in inflammatory airway diseases like asthma. In this study, bronchoconstrictor reactivity to NKA was measured in beagle dogs neonatally sensitized to and challenged with ragweed. Comparisons were made to histamine and methacholine. Lung resistance (R(L)) and dynamic lung compliance (C(Dyn)) were measured in anesthetized, spontaneously breathing dogs before and after aerosol challenge with NKA, histamine or methacholine. The concentration of these agents increasing R(L)by 25% above baseline (PC(25)) was calculated before and 24 h after aerosolized ragweed challenge. Before ragweed, the bronchoconstrictor reactivity to NKA was four-fold higher in ragweed-sensitized dogs (PC(25)=0.036+/-0.006%) compared to non-sensitized controls (PC(25)=0.177+/-0.030%, P<0.05). On the other hand, there was no difference in the bronchoconstrictor reactivity to histamine or methacholine between these two groups. Twenty-four hours after ragweed challenge to sensitized dogs, NKA reactivity was unchanged from pre-ragweed values but histamine and methacholine reactivity was increased by 2-3-fold. These results demonstrate airway hyperresponsiveness to NKA, histamine and methacholine in allergic beagle dogs although hyperresponsiveness to NKA exists in these allergic dogs before an antigen challenge. This animal model may prove to be useful to evaluate the role of tachykinins in hyperractive airway diseases.

Impact of breast pumping on lactogenesis stage II after cesarean delivery: a randomized clinical trial

OBJECTIVE

Women at risk for delayed onset of lactation are often advised to pump their breasts before lactogenesis stage II to hasten the timing of this process. The effectiveness of this clinical practice has not been previously evaluated. This study investigates the effects of breast pumping before the onset of lactation on early milk transfer and subsequent breastfeeding duration among women giving birth by cesarean delivery.

METHODOLOGY

Sixty women were randomly assigned to either the pumping group (n = 30), which used a double electric breast pump for six 10- to 15-minute sessions from 24 to 72 hours postpartum, or to the control group (n = 30), which held the pump to their breasts without suction for the same amount of time. Milk transfer was assessed by test weighing infants before and after 3 breastfeeding sessions daily. Test weight data were fitted to a second-order polynomial curve, to predict milk transfer over time.

RESULTS

Breast pumping between 24 and 72 hours after cesarean delivery did not improve milk transfer. Participants in the pumping group tended to have lower milk transfer than did controls. Primiparae in the pumping group breastfed for ~5 months less than their counterparts in the control group; however, this difference was not statistically significant.

CONCLUSIONS

Breast pumping did not improve milk transfer during the first 72 hours postpartum and may negatively affect breastfeeding duration among primiparous women. lactation, lactogenesis, breast milk, breast pumping, milk expression, breastfeeding, cesarean delivery.

[Cellular mechanisms of regulation of the inflammatory response in atherosclerosis: the role of cell contact-mediated signaling]

The regulatory mechanisms of the inflammatory process in the atherosclerotic plaque are still not clearly understood. Stimulated T cells may have a key role in enhancing and perpetuating inflammation at the atherosclerotic site. They activate endothelial cells, macrophages and smooth muscle cells in the atherosclerotic plaque, not only via the production of soluble mediators, but also through cell-cell contact-mediated interactions (via membrane receptors and their ligands). Cell/cell contact between stimulated T lymphocytes and monocytes/macrophages and endothelial cells induces the production of pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin-6) and chemokines (interleukin-8, monocyte chemotactic factor-1). Thus, these interactions could play a relevant role in the disregulation of the inflammatory process in the atherosclerotic plaque, representing a novel mechanism of progression and complication of the atherosclerotic disease. Understanding the key ligands and receptors involved may permit the definition of new therapeutic targets.

Observation of high-energy neutrinos using Cerenkov detectors embedded deep in Antarctic ice

Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water or ice. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations.