A continuum description of the buckling of a line of spheres in a transverse harmonic confining potential.

A line of contacting hard spheres, placed in a transverse confining potential, buckles under compression or when tilted away from the horizontal, once a critical tilt angle is exceeded. This interesting nonlinear problem is enriched by the combined application of both compression and tilt. In a continuous formulation, the profile of transverse sphere displacement is well described by numerical solutions of a second-order differential equation (provided that buckling is not of large amplitude). Here we provide a detailed discussion of these solutions, which are approximated by analytic expressions in terms of Jacobi, Whittaker and Airy functions. The analysis in terms of Whittaker functions yields an exact result for the critical tilt for buckling without compression.

Evidence of soft dipole resonance in

The first conclusive evidence of a dipole resonance in ^{11}Li having isoscalar character observed from inelastic scattering with a novel solid deuteron target is reported. The experiment was performed at the newly commissioned IRIS facility at TRIUMF. The results show a resonance peak at an excitation energy of 1.03±0.03 MeV with a width of 0.51±0.11 MeV (FWHM). The angular distribution is consistent with a dipole excitation in the distorted-wave Born approximation framework. The observed resonance energy together with shell model calculations show the first signature that the monopole tensor interaction is important in ^{11}Li. The first ab initio calculations in the coupled cluster framework are also presented.

The expression and impact of antifungal grooming in ants.

Parasites can cause extensive damage to animal societies in which many related individuals frequently interact. In response, social animals have evolved diverse individual and collective defences. Here, we measured the expression and efficiency of self-grooming and allo-grooming when workers of the ant Formica selysi were contaminated with spores of the fungal entomopathogen Metarhizium anisopliae. The amount of self-grooming increased in the presence of fungal spores, which shows that the ants are able to detect the risk of infection. In contrast, the amount of allo-grooming did not depend on fungal contamination. Workers groomed all nestmate workers that were re-introduced into their groups. The amount of allo-grooming towards noncontaminated individuals was higher when the group had been previously exposed to the pathogen. Allo-grooming decreased the number of fungal spores on the surface of contaminated workers, but did not prevent infection in the conditions tested (high dose of spores and late allo-grooming). The rate of disease transmission to groomers and other nestmates was extremely low. The systematic allo-grooming of all individuals returning to the colony, be they contaminated or not, is probably a simple but robust prophylactic defence preventing the spread of fungal diseases in insect societies.

Mixed mould species in laboratory cultures of respiratory specimens: how should they be reported, and what are the indications for susceptibility testing?

AIMS: To investigate how clinical microbiology laboratories should report and interpret mixed mould isolates including Aspergillus species from clinical samples and the criteria for susceptibility testing of the isolates. METHODS: Retrospectively collected data from our laboratory information system of moulds isolated between January 2005 and December 2007. Patient case notes were also reviewed. RESULTS: A total of 502 isolates (from 273 patients) were found. 20 patients with clinical diagnosis of a probable fungal infection had mixed Aspergillus species. CONCLUSIONS: In most instances, the isolation of Aspergillus species from non-sterile sites does not represent clinical disease, but only colonisation/contamination. However, for high-risk patients including transplant recipients, a positive culture is associated with invasive disease. Our tertiary centre routinely reports single fungal isolates and mixed cultures with appropriate comments, and those considered significant will also have susceptibility testing carried out. The correlation of culture results with clinical features can differentiate between invasive disease and contamination.

Population structure in a common Caribbean coral-reef fish: implications for larval dispersal and early life-history traits.

Genetic population structure throughout the Caribbean Basin for one of the most common and widespread reef fish species, the bicolour damselfish Stegastes partitus was examined using microsatellite DNA markers. Spatial autocorrelation analysis showed a significant positive correlation between genetic and geographic distance (isolation by distance) over distances <1000 km, suggesting that populations are connected genetically but probably not demographically, i.e. over shorter time scales. A difference in spatial patterns of populations in the eastern v. the western Caribbean also raises the probability of an important role for meso-scale oceanographic features and landscape complexity within the same species. A comparison of S. partitus population structure and life-history traits with those of two other species of Caribbean reef fish studied earlier showed the findings to be concordant with a common hypothesis that shorter pelagic larval dispersal periods are associated with smaller larval dispersal scales.

Selective synthesis of the C3v isomer of C60h18.

[chemical structure: see text]. C60H18 has been produced by hydrogenation of C60 at 100 bar H2 pressure and 673 K for 10 h. We have investigated the crude material without any purification by use of 1H NMR, 13C NMR, and IR spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry. We show that the crude material consists of 95% of the C3v isomer of C60H18.

Airway cellularity, lipid laden macrophages and microbiology of gastric juice and airways in children with reflux oesophagitis.

BACKGROUND: Gastroesophageal reflux disease (GORD) can cause respiratory disease in children from recurrent aspiration of gastric contents. GORD can be defined in several ways and one of the most common method is presence of reflux oesophagitis. In children with GORD and respiratory disease, airway neutrophilia has been described. However, there are no prospective studies that have examined airway cellularity in children with GORD but without respiratory disease. The aims of the study were to compare (1) BAL cellularity and lipid laden macrophage index (LLMI) and, (2) microbiology of BAL and gastric juices of children with GORD (G+) to those without (G-). METHODS: In 150 children aged < 14-years, gastric aspirates and bronchoscopic airway lavage (BAL) were obtained during elective flexible upper endoscopy. GORD was defined as presence of reflux oesophagitis on distal oesophageal biopsies. RESULTS: BAL neutrophil% in G- group (n = 63) was marginally but significantly higher than that in the G+ group (n = 77), (median of 7.5 and 5 respectively, p = 0.002). Lipid laden macrophage index (LLMI), BAL percentages of lymphocyte, eosinophil and macrophage were similar between groups. Viral studies were negative in all, bacterial cultures positive in 20.7% of BALs and in 5.3% of gastric aspirates. BAL cultures did not reflect gastric aspirate cultures in all but one child. CONCLUSION: In children without respiratory disease, GORD defined by presence of reflux oesophagitis, is not associated with BAL cellular profile or LLMI abnormality. Abnormal microbiology of the airways, when present, is not related to reflux oesophagitis and does not reflect that of gastric juices.

Leptin receptor expression in fetal lung increases in late gestation in the baboon: a model for human pregnancy.

Leptin produced by both adipose tissue and the placental trophoblast, has been proposed to regulate numerous aspects of human conceptus development. Although recent animal studies have suggested an additional role for the polypeptide in fetal lung maturation, no evidence has been reported in primates. Therefore, we employed the baboon (Papio sp.), a well-characterized primate model for human pregnancy, to determine the presence and ontogeny of leptin receptor in fetal lung with advancing gestation. Lungs were collected from fetal baboons, early in gestation (days 58-62, n = 4), at mid gestation (days 98-102, n = 4), and late in gestation (days 158-165, n = 4) (term 184 days). mRNA transcripts for leptin (LEP) and both long and short intracellular domain isoforms of the leptin receptor (LEP-R(L) and LEP-R(S)) were assessed by RT-PCR. leptin receptor protein was evaluated by immunoblotting and cell types expressing leptin receptor were identified in late pregnancy by immunohistochemistry. Fetal serum leptin concentrations, determined by RIA, remained relatively unchanged at 5.7 +/- 1.1 ng/ml (mean +/- s.e.m.) in mid pregnancy and 8.4 +/- 3.0 ng/ml in late pregnancy (P > 0.05). Although leptin were detectable in fetal lung, no changes in transcript abundance were apparent with advancing gestation. However, transcripts for both LEP-R(L) and LEP-R(S) receptor isoforms increased several-fold (P < 0.05) in fetal lung between mid and late gestation, while leptin receptor protein was detectable only in late pregnancy. leptin receptor was localized in distal pulmonary epithelial cells, including type II pneumocytes. In conclusion, leptin is present in the fetal baboon and its receptor is enhanced during late gestation in cells responsible for the synthesis of pulmonary surfactant. Collectively, these and past findings may suggest a modulatory role for the polypeptide in pulmonary development and/or may identify leptin receptor as a physiological marker of primate fetal lung maturity.

Transient early post-inoculation anti-retroviral treatment facilitates controlled infection with sparing of CD4+ T cells in gut-associated lymphoid tissues in SIVmac239-infected rhesus macaques, but not resistance to rechallenge.

Like human immunodeficiency virus infection of humans, infection of rhesus macaques with pathogenic simian immunodeficiency virus (SIV) strains typically results in persistent progressive infection, leading to clinically significant immunosuppression. In previous studies, we administered short term anti-retroviral treatment, shortly after intravenous inoculation with SIVsmE660, in an effort to allow immunologic sensitization under conditions not characterized by overwhelming cytopathic infection compromising the developing immune response. We showed that such treatment allowed control of off treatment viremia and was associated with resistance to rechallenge. Control of off treatment viremia was associated, at least in part, with CD8+ lymphocytes, based on in vivo CD8 depletion studies. In the present study, six rhesus macaques were infected intravenously with 100 MID50 of SIVmac239; four then received 30 days of treatment with tenofovir 9-[2-(R)-(phosphonomethoxy)propyl]adenine (PMPA); 20-30 mg/kg, subcutaneously) starting 24 hours post-inoculation. Tenofovir-treated animals showed low (<500 copy Eq/ml) or undetectable (<100 copy Eq/ml) plasma SIV RNA levels during treatment, with undetectable plasma viremia following discontinuation of treatment. Plasma SIV RNA remained <100 copy Eq/ml, even after depletion of CD8+ lymphocytes, 6 weeks after discontinuation of tenofovir treatment. In contrast to untreated infected control animals that showed substantial depletion of CD4+ T cells from gut-associated lymphoid tissues (GALT), tenofovir-treated animals showed sparing of GALT CD4+ T cells both during the treatment period and in the off treatment follow-up period. However, in contrast to earlier results with animals infected with SIVsmE660, in the present study, the animals did not develop readily measurable cellular anti-SIV immune responses, and did not resist homologous rechallenge with SIVmac239, administered 44 weeks after the initial infection. Differences in the animals and virus strains employed may in part account for the differences in results observed. Comparative analysis of virologic and immunologic parameters in this model system may provide important insights for understanding the basis of effective immunologic control of SIV infection.

The time-course of the response to the FMRFamide-related peptide PF4 in Ascaris suum muscle cells indicates direct gating of a chloride ion-channel.

We investigated the effects of PF4 on Ascaris suum somatic muscle cells using a 2 electrode current-clamp technique. PF4 is a FaRP (FMRFamide-related peptide), originally isolated from the free-living nematode Panagrellus redivivus. PF4 caused hyperpolarization and an increase in chloride ion conductance when it was applied to the muscle cells of the Ascaris body wall. The delay between the application of the peptide and the appearance of the response was measured and compared with that of gamma-amino butyric acid (GABA), a compound that directly gates ion channels, and with PF1, a FaRP that acts via an intracellular signal transduction mechanism. The PF4 and GABA delay times were not significantly different; they were 1.51+/-0.11 sec and 1.22+/-0.10 sec respectively. The delay following application of PF1, 3.75+/-0.51 sec, was significantly longer. The rapid response to PF4 is consistent with direct gating of a chloride ion channel, which has not been described elsewhere in the literature.

Antibody response to IR6, a conserved immunodominant region of the VlsE lipoprotein, wanes rapidly after antibiotic treatment of Borrelia burgdorferi infection in experimental animals and in humans.

Invariable region (IR)(6), an immunodominant conserved region of VlsE, the antigenic variation protein of Borrelia burgdorferi, is currently used for the serologic diagnosis of Lyme disease in humans and canines. A longitudinal assessment of anti-IR(6) antibody levels in B. burgdorferi-infected rhesus monkeys revealed that this level diminished sharply after antibiotic treatment (within 25 weeks). In contrast, antibody levels to P39 and to whole-cell antigen extracts of B. burgdorferi either remained unchanged or diminished less. A longitudinal analysis in dogs yielded similar results. In humans, the anti-IR(6) antibody titer diminished by a factor of > or =4 in successfully treated patients and by a factor of <4 in treatment-resistant patients. This result suggests that the quantification of anti-IR(6) antibody titer as a function of time should be investigated further as a test to assess response to Lyme disease therapy or to determine whether a B. burgdorferi infection has been eliminated.

Expression and chloroplast targeting of cholesterol oxidase in transgenic tobacco plants.

Cholesterol oxidase represents a novel type of insecticidal protein with potent activity against the cotton boll weevil (Anthonomus grandis grandis Boheman). We transformed tobacco (Nicotiana tabacum) plants with the cholesterol oxidase choM gene and expressed cytosolic and chloroplast-targeted versions of the ChoM protein. Transgenic leaf tissues expressing cholesterol oxidase exerted insecticidal activity against boll weevil larvae. Our results indicate that cholesterol oxidase can metabolize phytosterols in vivo when produced cytosolically or when targeted to chloroplasts. The transgenic plants exhibiting cytosolic expression accumulated low levels of saturated sterols known as stanols, and displayed severe developmental aberrations. In contrast, the transgenic plants expressing chloroplast-targeted cholesterol oxidase maintained a greater accumulation of stanols, and appeared phenotypically and developmentally normal. These results are discussed within the context of plant sterol distribution and metabolism.

Expanded polyglutamine peptides alone are intrinsically cytotoxic and cause neurodegeneration in Drosophila.

Several dominant, late-onset neurodegenerative diseases (e.g. Huntington's disease) are caused by expansion of polyglutamine (polyQ) repeats within specific proteins. The diverse, yet overlapping, pathology of these diseases could be due to novel deleterious functions unique to each protein or to a common pathophysiology mediated by the long polyQ chains themselves. By engineering Drosophila to express different polyQ peptides, we find that expanded polyQ chains alone are intrinsically cytotoxic and cause neuronal degeneration and early adult death. We further find that this intrinsic toxicity is dependent on cell type and polyQ length and that the inclusion of other amino acids modifies and reduces toxicity. This is the first in vivo evidence that polyQs, when removed from their disease gene context, cause neurotoxicity. These studies provide a basis for understanding the diverse clinical presentations in terms of the intrinsic cytotoxic effect of polyQ peptides being modulated by protein context. Parallel experiments in which cytotoxic polyQ expansions were engineered into Dishevelled, a Drosophila protein containing a naturally occurring polyQ tract, strongly suggest that the effect of a toxic polyQ peptide can be neutralized by protein context. This animal model provides a simple and effective means of screening for therapeutics that relieves the polyQ-induced lethality, independent of any particular disease gene. By quantifying the degree of lethality in several transgenic lines, we have identified a number of genetically modified strains that are suitable for eventual testing of compounds or genes that ameliorate the pathology of polyQ peptides.

Factors associated with outcomes 3 months after implantable cardioverter defibrillator insertion.

BACKGROUND: Adjustment to living with an implantable cardioverter defibrillator (ICD) is a dynamic process that varies among individuals. The purpose of this study was to describe patterns of recovery and to examine the relationships among demographic and clinical factors, illness appraisal and coping behaviors, and outcomes of physical and emotional function in the early recovery period of the first 3 months after initial ICD insertion. METHODS: Data were collected in the acute care setting and again at 1 and 3 months after ICD insertion. Subjects were 213 patients (83% men), ages 24-85 (mean 59.6) years. Demographic and clinical variables representing personal and situational factors, illness appraisal, and coping variables were examined using hierarchical multiple-regression analyses to predict outcomes of mood disturbance and functional status. RESULTS: The data revealed that symptoms, illness appraisal, and coping behaviors significantly explained additional variance in both functional status and mood disturbance above that accounted for by the less modifiable demographic and clinical variables. CONCLUSIONS: Symptoms, illness appraisal, and coping behaviors were predictors of outcomes in ICD patients. These factors are modifiable aspects of the recovery process, and interventions aimed at symptom management, appraisal reframing, and coping training should be tested to improve mood and functional outcomes for ICD patients.

Gradient of microglial activation in the brain of SIV infected macaques.

Brains of macaques inoculated with macrophage-tropic, neurovirulent virus 7F, with lymphocyte-tropic SIV mac239, or with dual-tropic SIVmac239/1yE, were examined for microglial activation, astrocyte activation, apoptosis and neuron loss. The brain one animal inoculated with neurovirulent virus 7f showed massive microglial activation as assessed by expression of the major histo-compatibility complex class II (MHC-II). In this animal very numerous, large microglial nodules expressing MHC-II were concentrated in the basal pons and internal capsule. These microglial nodules contained cells undergoing apoptosis detected by in situ end labeling of fragmented DNA. In this animal, neuron loss was apparent near the microglial nodules. In the animals inoculated with SIVmac239 or SIVmac239/17E, pathologic changes such as perivascular cuffing and formation of microglial nodules were absent. However, increased expression of MHC-11 by microglial cells was also concentrated in white matter of the basal pons, midbrain and internal capsule. These results indicate the microglial activation in SIV-infected macaques follows a ventral to dorsal gradient regardless of viral tropism. These results also show that the type and severity of neuropathological changes in SIV-infected macaques is highly dependent on the tropism of the inoculated virus.

Interviewing techniques with adolescents in primary care.

PURPOSE: Privacy is of utmost concern to adolescents seeking advice regarding life-style and behavior choices. Lack of privacy and confidential health services are barriers to adolescents' access to health care. This study describes primary care physicians' practices with regard to inviting parent(s) to leave the room in order to interview the teen alone, and the factors associated with use of this technique. METHOD: A cross-sectional random survey of 1,630 pediatricians, internists, and family practitioners in a large metropolitan area was performed using a confidential mailed questionnaire. RESULTS: The majority of the physicians were in private practice, male, board certified, Caucasian, and did not have a subspecialty. Forty-nine percent of the respondents "almost always" or "always" invite parent(s) to leave the room in order to interview the teen alone. Physicians who were female, board certified, and completed residency from 1974-94 were most likely to use this technique. Among physicians who frequently employ this strategy, the decision to interview the teen alone varied according to the clinical scenario. Using logistic regression analysis, only gender and board certification were significantly related to use of this interviewing method. CONCLUSION: A large proportion of physicians do not interview their adolescent patients alone, therefore, not affording them privacy to discuss confidential health concerns. Future research should focus on developing and validating methods to teach physicians skills to interview adolescents privately.

Effect of Salinity on Ionic Shifts in Mesohaline Scyphomedusae, Chrysaora quinquecirrha.

Mesohaline populations of the scyphomedusae Chrysaora quinquecirrha are found in salinities ranging from 5{permill} to 25{permill}. Osmotic and ionic adjustments within this salinity range were investigated using C. quinquecirrha ephyrae budded from polyps in the laboratory and young medusae collected from the mid-salinity region of the Patuxent River, Maryland. When medusae were transferred from 20{permill} salinity to lower salinities (8{permill}, 12{permill}), concentrations of sodium and magnesium in tissue and mesogleal fluid fell rapidly and approached those of dilute seawater within 6 hours. There was some recovery of these levels relative to the 8{permill} medium, and they were significantly higher than the dilute seawater concentration after 1 week. Tissue concentrations of calcium showed no evidence of being regulated, whereas potassium was strongly regulated such that levels did not fall significantly following transfer of medusae to lower salinities. However, after 1 week, the concentration of potassium in mesogleal fluid approached that of the dilute medium. Extracellular space measured by direct blotting and weighing or using 35S was about 40%. As a result, estimates for intracellular potassium were revised to 17 mM1-1. The concentration of potassium in tissue remained stable following transfer to lower salinity, despite a substantial osmotic influx of water. This influx was measured as a >20% gain in body weight over 24 h following transfer of medusae from 16{permill} to 8{permill}. Mesogleal fluid was slightly hypo-osmolar to the medium at 15% and 20{permill} and slightly hyperosmolar to the medium at 5{permill} and 12{permill}. Sulfate concentrations in mesogleal fluid were 66%-70% those of the external medium. Medusae died or were unable to achieve positive buoyancy at 5%{permill}, which is probably very close to a lower salinity limit for C. quinquecirrha in the mesohaline Chesapeake Bay.