Observation of the effect of gravity on the motion of antimatter

Einstein's general theory of relativity from 19151 remains the most successful description of gravitation. From the 1919 solar eclipse2 to the observation of gravitational waves3, the theory has passed many crucial experimental tests. However, the evolving concepts of dark matter and dark energy illustrate that there is much to be learned about the gravitating content of the universe. Singularities in the general theory of relativity and the lack of a quantum theory of gravity suggest that our picture is incomplete. It is thus prudent to explore gravity in exotic physical systems. Antimatter was unknown to Einstein in 1915. Dirac's theory4 appeared in 1928; the positron was observed5 in 1932. There has since been much speculation about gravity and antimatter. The theoretical consensus is that any laboratory mass must be attracted6 by the Earth, although some authors have considered the cosmological consequences if antimatter should be repelled by matter7-10. In the general theory of relativity, the weak equivalence principle (WEP) requires that all masses react identically to gravity, independent of their internal structure. Here we show that antihydrogen atoms, released from magnetic confinement in the ALPHA-g apparatus, behave in a way consistent with gravitational attraction to the Earth. Repulsive 'antigravity' is ruled out in this case. This experiment paves the way for precision studies of the magnitude of the gravitational acceleration between anti-atoms and the Earth to test the WEP.

Human Echolocators Have Better Localization Off Axis

Here, we report novel empirical results from a psychophysical experiment in which we tested the echolocation abilities of nine blind adult human experts in click-based echolocation. We found that they had better acuity in localizing a target and used lower intensity emissions (i.e., mouth clicks) when a target was placed 45° off to the side compared with when it was placed at 0° (straight ahead). We provide a possible explanation of the behavioral result in terms of binaural-intensity signals, which appear to change more rapidly around 45°. The finding that echolocators have better echo-localization off axis is surprising, because for human source localization (i.e., regular spatial hearing), it is well known that performance is best when targets are straight ahead (0°) and decreases as targets move farther to the side. This may suggest that human echolocation and source hearing rely on different acoustic cues and that human spatial hearing has more facets than previously thought.

Global COVID-19 lockdown highlights humans as both threats and custodians of the environment

The global lockdown to mitigate COVID-19 pandemic health risks has altered human interactions with nature. Here, we report immediate impacts of changes in human activities on wildlife and environmental threats during the early lockdown months of 2020, based on 877 qualitative reports and 332 quantitative assessments from 89 different studies. Hundreds of reports of unusual species observations from around the world suggest that animals quickly responded to the reductions in human presence. However, negative effects of lockdown on conservation also emerged, as confinement resulted in some park officials being unable to perform conservation, restoration and enforcement tasks, resulting in local increases in illegal activities such as hunting. Overall, there is a complex mixture of positive and negative effects of the pandemic lockdown on nature, all of which have the potential to lead to cascading responses which in turn impact wildlife and nature conservation. While the net effect of the lockdown will need to be assessed over years as data becomes available and persistent effects emerge, immediate responses were detected across the world. Thus, initial qualitative and quantitative data arising from this serendipitous global quasi-experimental perturbation highlights the dual role that humans play in threatening and protecting species and ecosystems. Pathways to favorably tilt this delicate balance include reducing impacts and increasing conservation effectiveness.

Crocodile social environments dictated by male philopatry

Examining the social behaviors of solitary species can be challenging due to the rarity in which interactions occur and the large and often inaccessible areas which these animals inhabit. As shared space-use is a prerequisite for the expression of social behaviors, we can gain insights into the social environments of solitary species by examining the degree of spatial overlap between individuals. Over a 10-year period, we examined how spatial overlap amongst 105 estuarine crocodiles Crocodylus porosus was influenced by season, sex, and movement tactic. We discovered that crocodiles displayed highly consistent spatial overlaps with conspecifics between months and across years. Furthermore, male crocodiles that exhibited a greater degree of site fidelity displayed more stable social environments, while females and males that were less site-attached had more dynamic social environments with spatial overlaps between conspecifics peaking during the mating season. Our results demonstrate how long-term tracking of multiple individuals within the same population can be used to quantify the spatial structure and social environment of cryptic and solitary species.

Sympathetic cooling of positrons to cryogenic temperatures for antihydrogen production

The positron, the antiparticle of the electron, predicted by Dirac in 1931 and discovered by Anderson in 1933, plays a key role in many scientific and everyday endeavours. Notably, the positron is a constituent of antihydrogen, the only long-lived neutral antimatter bound state that can currently be synthesized at low energy, presenting a prominent system for testing fundamental symmetries with high precision. Here, we report on the use of laser cooled Be+ ions to sympathetically cool a large and dense plasma of positrons to directly measured temperatures below 7 K in a Penning trap for antihydrogen synthesis. This will likely herald a significant increase in the amount of antihydrogen available for experimentation, thus facilitating further improvements in studies of fundamental symmetries.

Laser cooling of antihydrogen atoms

The photon-the quantum excitation of the electromagnetic field-is massless but carries momentum. A photon can therefore exert a force on an object upon collision1. Slowing the translational motion of atoms and ions by application of such a force2,3, known as laser cooling, was first demonstrated 40 years ago4,5. It revolutionized atomic physics over the following decades6-8, and it is now a workhorse in many fields, including studies on quantum degenerate gases, quantum information, atomic clocks and tests of fundamental physics. However, this technique has not yet been applied to antimatter. Here we demonstrate laser cooling of antihydrogen9, the antimatter atom consisting of an antiproton and a positron. By exciting the 1S-2P transition in antihydrogen with pulsed, narrow-linewidth, Lyman-α laser radiation10,11, we Doppler-cool a sample of magnetically trapped antihydrogen. Although we apply laser cooling in only one dimension, the trap couples the longitudinal and transverse motions of the anti-atoms, leading to cooling in all three dimensions. We observe a reduction in the median transverse energy by more than an order of magnitude-with a substantial fraction of the anti-atoms attaining submicroelectronvolt transverse kinetic energies. We also report the observation of the laser-driven 1S-2S transition in samples of laser-cooled antihydrogen atoms. The observed spectral line is approximately four times narrower than that obtained without laser cooling. The demonstration of laser cooling and its immediate application has far-reaching implications for antimatter studies. A more localized, denser and colder sample of antihydrogen will drastically improve spectroscopic11-13 and gravitational14 studies of antihydrogen in ongoing experiments. Furthermore, the demonstrated ability to manipulate the motion of antimatter atoms by laser light will potentially provide ground-breaking opportunities for future experiments, such as anti-atomic fountains, anti-atom interferometry and the creation of antimatter molecules.

Human Click-Based Echolocation of Distance: Superfine Acuity and Dynamic Clicking Behaviour

Some people who are blind have trained themselves in echolocation using mouth clicks. Here, we provide the first report of psychophysical and clicking data during echolocation of distance from a group of 8 blind people with experience in mouth click-based echolocation (daily use for > 3 years). We found that experienced echolocators can detect changes in distance of 3 cm at a reference distance of 50 cm, and a change of 7 cm at a reference distance of 150 cm, regardless of object size (i.e. 28.5 cm vs. 80 cm diameter disk). Participants made mouth clicks that were more intense and they made more clicks for weaker reflectors (i.e. same object at farther distance, or smaller object at same distance), but number and intensity of clicks were adjusted independently from one another. The acuity we found is better than previous estimates based on samples of sighted participants without experience in echolocation or individual experienced participants (i.e. single blind echolocators tested) and highlights adaptation of the perceptual system in blind human echolocators. Further, the dynamic adaptive clicking behaviour we observed suggests that number and intensity of emissions serve separate functions to increase SNR. The data may serve as an inspiration for low-cost (i.e. non-array based) artificial ‘cognitive’ sonar and radar systems, i.e. signal design, adaptive pulse repetition rate and intensity. It will also be useful for instruction and guidance for new users of echolocation.

Ontogenetic shifts in the nesting behaviour of female crocodiles

Body size and age are crucial factors influencing reproductive capacity and success. As females grow, their reproductive investment and success often increase due to improved overall physiological condition and experience gained through successive reproductive events. While much of this work has been conducted on birds and mammals, surprisingly little is known on how body size affects nesting decisions in other long-lived vertebrates. We monitored the movements and nesting behaviour of 57 wild female estuarine crocodiles Crocodylus porosus over a 10-year period (and across consecutive nesting seasons) using externally mounted satellite tags, implanted acoustic transmitters and a network of submerged acoustic receivers. Applying Hidden Markov models to the telemetry-derived location data revealed that female nesting behaviours could be split into three distinct states: (i) ranging movements within home ranges and at nesting sites; (ii) migrations to and from nesting sites; (iii) and nesting/nest guarding. We found that during migration events, larger females migrated further and remained away from dry season territories for longer periods than smaller individuals. Furthermore, not only were migratory movements stimulated by increases in rainfall, larger females migrated to nest sites at lower rainfall thresholds than smaller females. We provide some of the first evidence of body size influencing nesting decisions in an ectothermic vertebrate, with shifts likely resulting from an increased willingness to invest in nest protection among larger and more experienced females.

Observation of the 1S-2P Lyman-α transition in antihydrogen

In 1906, Theodore Lyman discovered his eponymous series of transitions in the extreme-ultraviolet region of the atomic hydrogen spectrum1,2. The patterns in the hydrogen spectrum helped to establish the emerging theory of quantum mechanics, which we now know governs the world at the atomic scale. Since then, studies involving the Lyman-α line-the 1S-2P transition at a wavelength of 121.6 nanometres-have played an important part in physics and astronomy, as one of the most fundamental atomic transitions in the Universe. For example, this transition has long been used by astronomers studying the intergalactic medium and testing cosmological models via the so-called 'Lyman-α forest'3 of absorption lines at different redshifts. Here we report the observation of the Lyman-α transition in the antihydrogen atom, the antimatter counterpart of hydrogen. Using narrow-line-width, nanosecond-pulsed laser radiation, the 1S-2P transition was excited in magnetically trapped antihydrogen. The transition frequency at a field of 1.033 tesla was determined to be 2,466,051.7 ± 0.12 gigahertz (1σ uncertainty) and agrees with the prediction for hydrogen to a precision of 5 × 10-8. Comparisons of the properties of antihydrogen with those of its well-studied matter equivalent allow precision tests of fundamental symmetries between matter and antimatter. Alongside the ground-state hyperfine4,5 and 1S-2S transitions6,7 recently observed in antihydrogen, the Lyman-α transition will permit laser cooling of antihydrogen8,9, thus providing a cold and dense sample of anti-atoms for precision spectroscopy and gravity measurements10. In addition to the observation of this fundamental transition, this work represents both a decisive technological step towards laser cooling of antihydrogen, and the extension of antimatter spectroscopy to quantum states possessing orbital angular momentum.

Evaluation of air quality at the Birmingham New Street Railway Station

Air pollution from diesel emissions is becoming an increased international concern, and whilst attention has been primarily focused on the automotive industry, concerns have also been raised about emissions from diesel rail vehicles. This paper reports an extensive series of measurements made at the Birmingham New Street station, a major rail interchange in the Midlands of England, with a mix of diesel and electric train movements, which is of particular concern because of the enclosed nature of the platforms. This study was undertaken in collaboration with Network Rail to better understand the environment in and around the station over a longer period to provide a more detailed analysis of the complex environment at the station. The station environment has been considered in terms of the European Union (EU) and Department of Environment, Food and Rural Affairs (DEFRA) limits as part of the monitoring methodology, but it should be noted that these limits do not apply in this environment as the Management of Health and Safety at Work Regulation 1999 and the Control of Substances Hazardous to Health Regulations 2002 are applicable. The monitoring campaign consisted of diffusion tube measurements to measure nitrogen dioxide at a large number of different locations throughout and around the station. These were followed by detailed measurements of oxides of nitrogen, particulate matter, carbon dioxide and black carbon (a diesel tracer) at a smaller number of sites at the platform level. The results are analysed to give concentrations over a wide variety of time scales, and long- and short-term averages. The effects of ambient wind conditions and individual train movements are also considered. Recommendations are made for possible remedial measures and for future work to more fully understand the physical mechanisms involved.

Characterization of the 1S-2S transition in antihydrogen

In 1928, Dirac published an equation 1 that combined quantum mechanics and special relativity. Negative-energy solutions to this equation, rather than being unphysical as initially thought, represented a class of hitherto unobserved and unimagined particles-antimatter. The existence of particles of antimatter was confirmed with the discovery of the positron 2 (or anti-electron) by Anderson in 1932, but it is still unknown why matter, rather than antimatter, survived after the Big Bang. As a result, experimental studies of antimatter3-7, including tests of fundamental symmetries such as charge-parity and charge-parity-time, and searches for evidence of primordial antimatter, such as antihelium nuclei, have high priority in contemporary physics research. The fundamental role of the hydrogen atom in the evolution of the Universe and in the historical development of our understanding of quantum physics makes its antimatter counterpart-the antihydrogen atom-of particular interest. Current standard-model physics requires that hydrogen and antihydrogen have the same energy levels and spectral lines. The laser-driven 1S-2S transition was recently observed 8 in antihydrogen. Here we characterize one of the hyperfine components of this transition using magnetically trapped atoms of antihydrogen and compare it to model calculations for hydrogen in our apparatus. We find that the shape of the spectral line agrees very well with that expected for hydrogen and that the resonance frequency agrees with that in hydrogen to about 5 kilohertz out of 2.5 × 1015 hertz. This is consistent with charge-parity-time invariance at a relative precision of 2 × 10-12-two orders of magnitude more precise than the previous determination 8 -corresponding to an absolute energy sensitivity of 2 × 10-20 GeV.

Erratum: Observation of the hyperfine spectrum of antihydrogen

This corrects the article DOI: 10.1038/nature23446.

Enhanced Control and Reproducibility of Non-Neutral Plasmas

The simultaneous control of the density and particle number of non-neutral plasmas confined in Penning-Malmberg traps is demonstrated. Control is achieved by setting the plasma's density by applying a rotating electric field while simultaneously fixing its axial potential via evaporative cooling. This novel method is particularly useful for stabilizing positron plasmas, as the procedures used to collect positrons from radioactive sources typically yield plasmas with variable densities and particle numbers; it also simplifies optimization studies that require plasma parameter scans. The reproducibility achieved by applying this technique to the positron and electron plasmas used by the ALPHA antihydrogen experiment at CERN, combined with other developments, contributed to a 10-fold increase in the antiatom trapping rate.

Observation of the hyperfine spectrum of antihydrogen

The observation of hyperfine structure in atomic hydrogen by Rabi and co-workers and the measurement of the zero-field ground-state splitting at the level of seven parts in 10¹³ are important achievements of mid-twentieth-century physics. The work that led to these achievements also provided the first evidence for the anomalous magnetic moment of the electron, inspired Schwinger's relativistic theory of quantum electrodynamics and gave rise to the hydrogen maser, which is a critical component of modern navigation, geo-positioning and very-long-baseline interferometry systems. Research at the Antiproton Decelerator at CERN by the ALPHA collaboration extends these enquiries into the antimatter sector. Recently, tools have been developed that enable studies of the hyperfine structure of antihydrogen-the antimatter counterpart of hydrogen. The goal of such studies is to search for any differences that might exist between this archetypal pair of atoms, and thereby to test the fundamental principles on which quantum field theory is constructed. Magnetic trapping of antihydrogen atoms provides a means of studying them by combining electromagnetic interaction with detection techniques that are unique to antimatter. Here we report the results of a microwave spectroscopy experiment in which we probe the response of antihydrogen over a controlled range of frequencies. The data reveal clear and distinct signatures of two allowed transitions, from which we obtain a direct, magnetic-field-independent measurement of the hyperfine splitting. From a set of trials involving 194 detected atoms, we determine a splitting of 1,420.4 ± 0.5 megahertz, consistent with expectations for atomic hydrogen at the level of four parts in 10⁴. This observation of the detailed behaviour of a quantum transition in an atom of antihydrogen exemplifies tests of fundamental symmetries such as charge-parity-time in antimatter, and the techniques developed here will enable more-precise such tests.

Antihydrogen accumulation for fundamental symmetry tests

Antihydrogen, a positron bound to an antiproton, is the simplest anti-atom. Its structure and properties are expected to mirror those of the hydrogen atom. Prospects for precision comparisons of the two, as tests of fundamental symmetries, are driving a vibrant programme of research. In this regard, a limiting factor in most experiments is the availability of large numbers of cold ground state antihydrogen atoms. Here, we describe how an improved synthesis process results in a maximum rate of 10.5 ± 0.6 atoms trapped and detected per cycle, corresponding to more than an order of magnitude improvement over previous work. Additionally, we demonstrate how detailed control of electron, positron and antiproton plasmas enables repeated formation and trapping of antihydrogen atoms, with the simultaneous retention of atoms produced in previous cycles. We report a record of 54 detected annihilation events from a single release of the trapped anti-atoms accumulated from five consecutive cycles.

Antihydrogen studies are important in testing the fundamental principles of physics but producing antihydrogen in large amounts is challenging. Here the authors demonstrate an efficient and high-precision method for trapping and stacking antihydrogen by using controlled plasma.

Electron plasma orbits from competing diocotron drifts

The perpendicular dynamics of a pure electron plasma column are investigated when the plasma spans two Penning-Malmberg traps with noncoinciding axes. The plasma executes noncircular orbits described by competing image-charge electric-field (diocotron) drifts from the two traps. A simple model is presented that predicts a set of nested orbits in agreement with observed plasma trajectories.

Compression of positron clouds in the independent particle regime

The application of an asymmetric dipolar electric field rotating at a frequency close to that of the axial bounce of a collection of trapped positrons has, in the presence of a low pressure molecular gas to provide cooling, been used to achieve compression of the cloud. A theory of this effect has been developed for a Penning trap potential, with the cooling modeled in the Stokes viscous drag approximation. Good agreement between the theory and measurements of the frequency dependence of the cloud compression rate has been found, establishing that the phenomenon is a new form of sideband cooling.

Natural Occurrence of Phytophthora infestans Causing Late Blight on Woody Nightshade (Solanum dulcamara) in New York

Woody nightshade (Solanum dulcamara) is a common hedgerow herbaceous perennial in the United States, one of only three native Solanum spp. S. dulcamara is a known host of Phytophthora infestans (3), but infection is rarely reported. There is a U.S. record from Maryland (2); in 1947, Peterson (4) stated that this species had never been found blighted in its natural habitat, although in 1960 it was listed as a host of P. infestans in New York (1). The A2 mating type has not been reported on this host. On 2 July, 2009, leaf lesions similar to those of P. infestans on potato were found on wild S. dulcamara at Riverhead, NY. The plant was growing in a home garden within 10 m of potato and tomato plants infected with P. infestans. When two infected leaves of S. dulcamara were incubated for 24 h under high humidity, a pathogen growth developed around the lesion margins that was characterized by hyaline mycelium bearing lemon-shaped sporangia that released motile zoospores after chilling in water, which is consistent with P. infestans. The caducous and limoniform to ovoid sporangia were 39 to 50 μm (average 45 μm) × 26 to 28 μm (average 27 μm) with a length/breadth ratio of 1.66. No oospores were observed. Three isolates were obtained from this plant during July 2009. Growth on rye agar was indistinguishable from that of local tomato isolates of P. infestans. Detached leaflets of S. dulcamara and S. tuberosum, inoculated with the woody nightshade isolates and kept in a humid chamber, became infected and developed profuse sporulation within 5 days. The pathogen isolated was confirmed as P. infestans by morphological, biochemical, and molecular characteristics. Inoculations of attached leaves of potted S. dulcamara plants resulted in necrotic lesions with many sporangia; sporulation also developed on inoculated, attached, and detached tomato leaves. P. infestans was reisolated and identity confirmed as before. The three isolates were A2 mating type, metalaxyl-resistant, mitochondrial haplotype Ia. All were glucose-6-phosphate isomerase 100/122 and peptidase 100/100, as confirmed with single-spore isolates. RG57 fingerprint analysis confirmed that isolates from woody nightshade, tomato, and potato obtained from the same and nearby sites were identical. Although P. infestans in the United States belongs to the new population, which may infect a wider host range than the old US-1 clonal lineage, S. dulcamara infections have only been found when late blight is already widespread in neighboring fields and there is no evidence to suggest that woody nightshade acts as an overwintering host in the United States. References: (1) Anonymous. Index of Plant Diseases in the United States. Page 456 in: Agric. Handb. No. 165, 1960 (2) C. Cox. Phytopathology 38:575, 1948. (3) D. C. Erwin and O. K. Ribeiro. Page 190 in: Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (4) L. C. Peterson. Am. Potato J. 24:188, 1947.

Gene duplication event in family 12 glycosyl hydrolase from Phytophthora spp

A total of 18 paralogs of xyloglucan-specific endoglucanases (EGLs) from the glycosyl hydrolase family 12 were identified and characterized in Phytophthora sojae and Phytophthora ramorum. These genes encode predicted extracellular enzymes, with sizes ranging from 189 to 435 amino acid residues, that would be capable of hydrolyzing the xyloglucan component of the host cell wall. In two cases, four and six functional copies of these genes were found in tight succession within a region of 5 and 18 kb, respectively. The overall gene copy number and relative organization appeared well conserved between P. sojae and P. ramorum, with apparent synteny in this region of their respective genomes. Phylogenetic analyses of Phytophthora endoglucanases of family 12 and other known members of EGL 12, revealed a close relatedness with a fairly conserved gene sub-family containing, among others, sequences from the fungi Emericella desertorum and Aspergillus aculeatus. This is the first report of family 12 EGLs present in plant pathogenic eukaryotes.

Diversity of surface protein expression in group B streptococcal colonizing & invasive isolates

BACKGROUND & OBJECTIVES

The classification of group B streptococcal (GBS) isolates is based on the capsular polysaccharides (Ia-VIII), and antigenic characterization of clinical isolates is augmented by the detection of various surface-localized protein antigens. In our laboratory, all GBS isolates are routinely analysed for the alpha trypsin-resistant and the beta trypsin-sensitive c protein antigens, as well as other trypsin-resistant proteins R1, R3, and R4, as well as BPS. The purpose of this work was to study diversity of protein expression in colonizing isolates (vaginal and rectal sites) from nonpregnant women and from invasive isolates (blood or CSF) from mothers and their less than seven day old newborn infants.

METHODS

A total of 289 invasive isolates and 2660 colonizing isolates were collected between 1993-2002. All isolates were tested for polysaccharide serotype and cell surface-expressed protein profile by double immunoprecipation in agarose using monospecific antisera.

RESULTS

Among the 289 invasive isolates, 89.6 per cent expressed one or more trypsin-resistant proteins; 93 per cent of the colonizing isolates expressed one or more of these proteins. Overall, the most common surface protein expression profile by GBS serotype was: alpha in type Ia; alpha plus beta in type Ib; alpha and R4 in type II; R4 in type III; and co-expression of R1 plus R4 in isolates of type V. BPS was found in five (1.7%) invasive isolates, alone in two isolates and with other proteins in three isolates. Among 2660 colonizing isolates, BPS was found alone in 15 (0.6%) and in 57 additional isolates with other proteins. Among the total isolates, BPS was found predominantly in serotype Ia isolates, also expressing R1. Uncommon protein profiles of known serotypes included 11 type III isolates expressing alpha plus beta. Among 72 nontypable colonizing isolates, expression of R1 plus R4 was the commonest (33.3%) profile.

INTERPRETATION & CONCLUSION

The GBS surface proteins and the common serotypes were distributed comparably in colonizing and invasive isolates. Trypsin-resistant, alpha and alpha-like proteins, R1 and R4 were the most prevalent. The phenotypic diversity of the surface-localized protein antigens of GBS is intriguing, and genotypic analysis will permit consensus in nomenclature from laboratory to laboratory.

Group B streptococcal conjugate vaccines

Linkage of bacterial capsular polysaccharides to proteins to create conjugate vaccines has had a dramatic impact on the health of children. Although unconjugated polysaccharides are poorly immunogenic in infants and some older children and adults, their covalent coupling with proteins stimulates T cell dependent antigenic recognition that profoundly enhances immunogenicity. In the decade since the introduction and widespread use of Haemophilus influenzae type b polysaccharide conjugate vaccines in the United States, invasive H influenzae infections have become a rarity in childhood. Similarly, the conjugation of polysaccharides of Streptococcus pneumoniae to a derivative of diphtheria toxoid and the addition of pneumococcal conjugate vaccine to infant immunisation schedules carries with it promise for a similar decline in the incidence of invasive pneumococcal disease in paediatric patients.

Neonatal meningitis

Twelve years ago an annotation was published in Archives of Disease in Childhood regarding the antibiotic treatment of suspected neonatal meningitis. The authors recommended the use of cephalosporins rather than chloramphenicol and advocated intraventricular aminoglycoside treatment in selected cases. They noted the absence of clinical trials with third generation cephalosporins that showed an improvement in mortality or neurological outcome.

Effects of alum adjuvant or a booster dose on immunogenicity during clinical trials of group B streptococcal type III conjugate vaccines

Phase 1 and 2 clinical trials of group B streptococcal (GBS) capsular polysaccharide (CPS)-protein conjugate vaccines in healthy adults have demonstrated their safety and improved immunogenicity compared with uncoupled CPSs. Two recent trials sought to determine (i) whether adsorption of conjugate vaccine to aluminum hydroxide would improve immunogenicity and (ii) whether the CPS-specific immunoglobulin G (IgG) response could be boosted by administration of a second dose. Adsorption of GBS type III CPS-tetanus toxoid (III-TT) conjugate vaccine to alum did not improve the immune response to a 12.5-microg dose in healthy adult recipients. Four weeks after vaccination, the geometric mean antibody concentrations (GMCs) for the 15 recipients of III-TT with or without alum were 3.3 and 3.6 microg/ml, respectively. In the second trial, 36 healthy adults vaccinated previously with GBS III-TT conjugate were given a second 12.5-microg dose 21 months later. At 4 weeks after the second dose, the GMCs of type III CPS-specific IgG were similar to those measured 4 weeks after the primary vaccination, suggesting a lack of a booster response. However, 8 (22%) of the 36 participants who had undetectable III CPS-specific IgG (<0.05 microg/ml) before the first dose of III-TT conjugate exhibited a booster response to the second dose, with a fourfold-greater GMC of type III CPS-specific IgG than after the initial immunization. These results suggest that prior natural exposure to type III GBS or a related antigen may be responsible for the brisk IgG response to CPS noted in most adults after vaccination. However, a second dose of GBS III-TT conjugate vaccine may be required for adults whose initial CPS-specific IgG concentrations are very low and would also restore the initial peak-specific III CPS-IgG in responders to previous vaccination.

Regional topical hypothermia of the beating heart: preservation of function and tissue

BACKGROUND

Protection of the myocardium during beating heart operations is paramount. The goal of this study is to determine if regional topical hypothermia (RTH) preserves myocardial viability and function during periods of temporary coronary artery occlusion.

METHODS

Sixteen pigs were divided into two groups (RTH and control). Each group received 40 minutes of midleft anterior descending coronary occlusion followed by 3 hours of reperfusion. The RTH group (n = 10) received RTH and the control group (n = 6) received no cooling. Myocardial and core temperatures were measured with thermistors. Sonomicrometers and micromonameters were used to determine load independent indices of myocardial function. These indices were measured at base line, during coronary occlusion, and at 3 hours of reperfusion. The myocardium at risk and the infarct area were determined with monastral blue dye and triphenyl tetrazolium chloride staining.

RESULTS

The mean myocardial temperature in the risk zone during coronary occlusion was significantly less in the RTH group (29.4 degrees C +/- 5.6 degrees C versus 35.7 degrees C +/- 1.1 degrees C, p < 0.05). After 40 minutes of coronary occlusion, both the RTH group and control had a significant reduction in regional elastance (9.38 +/- 3.54 and 11.05 +/- 1.67 mm Hg/mm) compared with base line measurements (14.70 +/- 2.42 and 16.80 +/- 4.79 mm Hg/mm), p < 0.05. However, after 3 hours of reperfusion, the elastance returned to base line levels in the RTH group (15.83 +/- 3.06 mm Hg/mm) but remained significantly depressed in the control group (9.97 +/- 3.63 mm Hg/mm, p < 0.04). Myocardial necrosis as a percentage of the risk zone was significantly less in the hypothermia group (25% +/- 2% versus 62% +/- 5%, p < 0.001).

CONCLUSIONS

Regional topical hypothermia during isolated temporary coronary occlusion provides regional myocardial protection expressed as a return of function and decreased necrosis. Regional topical hypothermia may be clinically applicable to myocardial preservation during beating heart operations.

Antibodies to capsular polysaccharides of group B Streptococcus in pregnant Canadian women: relationship to colonization status and infection in the neonate

In a cohort study of 1207 pregnant women in Alberta, Canada, the serotype distributions of vaginal-rectal group B Streptococcus (GBS) isolates were compared with all isolates from neonates with invasive GBS disease identified by population-based surveillance. Serum concentrations of Ia, Ib, II, III, and V capsular polysaccharide (CPS)-specific IgG also were determined, according to serotype of the vaginal-rectal colonizing GBS strain. GBS colonization was detected in 19.5% (235 of 1207) of women. Serotype III accounted for 20.6% (48 of 233) of colonizing strains available for typing but for 37% (27 of 73) of invasive isolates from neonates (P<.01). Maternal colonization with type III was least likely to be associated with moderate concentrations of III CPS-specific IgG. Serotype III GBS is more invasive than other serotypes in this population; this may be due, at least in part, to poor maternal type III CPS-specific antibody response.

A novel paracorporeal method for isolated rodent lung reperfusion

BACKGROUND

The isolated perfused lung model is commonly used in small animals to study lung function after preservation and cold storage. Measurements of oxygenation, compliance, and capillary filtration coefficient (Kf) permit analysis of preservation solutions or modifications of these solutions. However, inter-investigator variability using different perfusates makes comparisons difficult. Whole blood perfusion more closely mimics the in vivo situation, but extracorporeal circulation may alter the physiologic integrity of the model. Paracorporeal support has been used, but this technique required mechanical ventilation of the support rodent and did not incorporate a method for determining Kf. We evaluated a less-invasive technique, of providing cross-circulatory syngeneic support, maintaining the ability to compute Kf.

METHODS

Angiocatheters were inserted into both femoral arteries and one femoral vein of the support rat. The venous cannula was connected to the pulmonary artery of the ex vivo lung block to provide inflow. Pulmonary effluent blood from the lung block was collected via a left atrial cannula and returned to the support rat via the femoral artery. A separate, height-adjustable column was included in the circuit for measurement of Kf.

RESULTS

Each support rat was used to sequentially perfuse three double-lung blocks. The inflow sample to each lung block was analyzed for pH, pO2, pCO2, and hematocrit to follow alterations in support rat physiology. There were no statistical differences in the pH, PO2, or hematocrit. No significant differences were noted in the pO2 of the pulmonary effluent blood or the Kf; analyzed to determine whether the sequence of reperfusion affected the pulmonary function assessment.

CONCLUSIONS

The syngeneic support rat delivers constant pressure systemic venous blood at stable physiologic parameters to the ex vivo lung block. Recirculation of the perfusate through the support rat diminishes the need to pool blood from donors, detoxifies and deoxygenates pulmonary effluent blood, and permits examination of sequential lung blocks. This technique represents a hybrid model between isolated perfused and orthotopic transplant models, maintaining Kf determination, a sensitive indicator of reperfusion injury. This technique could be applicable to reperfusion injury models of other organs (using arterial inflow instead) and may permit increased standardization among investigators.

Midterm results of the Ross procedure

BACKGROUND

The optimal hemodynamic performance and potential growth of the pulmonary autograft has led to expanded indications for the Ross procedure. We reviewed our institutional experience to assess midterm results with the Ross operation.

METHODS

In a 7-year period (1992 to 1999), 111 patients with a median age of 15.7 years (range 2 days to 67 years), underwent the Ross procedure. Ninety-five patients had isolated aortic valve disease and 16 pediatric patients had a more complex left ventricular outflow tract obstruction.

RESULTS

There were 3 early (2.7%) and 3 late deaths over a median follow-up of 3.6 years (range 6 months to 7.6 years). Actuarial survival at 5 years was 94%+/-2%. In pediatric patients, the pulmonary autograft annulus enlarged from 14.7+/-6.2 mm to 22+/-6.3 mm. This growth followed the expected increase in pulmonary valve diameter based on body surface area. Eight reoperations were necessary for autograft insufficiency at a median interval of 14 months (range 2 days to 31 months). Freedom from replacement of the pulmonary autograft was 91%+/-3% at 5 years. Three patients developed important obstruction of the pulmonary homograft requiring reoperation at a median of 29 months (range 9 to 31 months).

CONCLUSIONS

The Ross procedure can be performed with good midterm results. In pediatric patients, autograft growth has been appropriate. The potential for development of important autograft insufficiency suggests close follow-up through the intermediate and late term.

Magnetic resonance imaging in a child with primary sternal osteomyelitis

Primary sternal osteomyelitis (PSO) is rare. In a 9-year-old boy with Staphylococcus aureus bacteremia, magnetic resonance imaging helped to promptly establish the diagnosis of PSO. Eleven previously reported cases are reviewed, emphasiz ing surgical drainage and antimicrobial therapy for optimal outcome. Magnetic resonance imaging may be superior to other imaging studies for the diagnosis of PSO.

Failure of rifampin to eradicate group B streptococcal colonization in infants

BACKGROUND

Mucous membrane colonization with group B streptococci (GBS) frequently persists in infants after treatment of invasive infection and may be associated with recurrent disease.

OBJECTIVE

To determine the frequency with which GBS colonization persists at mucous membrane sites after treatment of invasive early or late onset infection and to determine the efficacy of oral rifampin in eradicating colonization in these infants and their mothers.

METHODS

Cultures for isolation of GBS were obtained from infants and their mothers after completion of the infant's parenteral therapy, 1 week later when rifampin therapy was initiated and at approximately 1 and 4 weeks after completion of rifampin therapy. Rifampin was administered (10-mg/kg dose; maximum, 600 mg) twice daily for 4 days.

RESULTS

Ten of 21 infants (48%) and 13 (65%) of their 20 mothers were colonized with GBS at throat or rectal (infant) or vaginal, rectal or breast milk (mother) sites before rifampin was initiated. One week or less after rifampin treatment, 7 (70%) infants and 4 (31%) mothers remained colonized with GBS. At study completion 6 infants and 7 mothers had GBS colonization. Persistent colonization was not related to GBS serotype, to initial rifampin minimal inhibitory concentration or to the development of rifampin resistant strains.

CONCLUSIONS

Rifampin treatment for four days utilized as a single agent after completion of parenteral therapy failed to reliably eradicate GBS colonization in infants.

Ophthalmologic, visceral, and cardiac involvement in neonates with candidemia

A retrospective review of 86 neonates with candidemia hospitalized from January 1989 through June 1999 was conducted to determine the frequency of ophthalmologic, visceral, or cardiac involvement. Retinal abnormalities were observed in 4 (6%) of the 67 infants in whom indirect ophthalmoscopy examination was performed. Abdominal ultrasound abnormalities were detected in 5 (7.7%) of 65 infants. Echocardiogram revealed thrombi or vegetations in 11 (15.2%) of 72 infants. Age at onset, presence of central venous catheters, and species of Candida were not predictors for involvement at these sites. Infants with candidemia that lasted > or =5 days were more likely to demonstrate ophthalmologic, renal, or cardiac abnormalities than those with a shorter duration. Infants with involvement of these organs received larger cumulative doses of amphotericin B than those without detectable abnormalities. Because complication of disseminated candidiasis by eye, renal, or cardiac involvement has therapeutic implications, and because risk factors for candidemia inadequately predict these complications, evaluations are indicated for all neonates with candidemia.

Bayesian inference on protective antibody levels using case-control data

In the study of immune responses to infectious pathogens, the minimum protective antibody concentration (MPAC) is a quantity of great interest. We use case-control data to estimate the posterior distribution of the conditional risk of disease given a lower bound on antibody concentration in an at-risk subject. The concentration bound beyond which there is high credibility that infection risk is zero or nearly so is a candidate for the MPAC. A very simple Gibbs sampling procedure that permits inference on the risk of disease given antibody level is presented. In problems involving small numbers of patients, the procedure is shown to have favorable accuracy and robustness to choice/misspecification of priors. Frequentist evaluation indicates good coverage probabilities of credibility intervals for antibody-dependent risk, and rules for estimation of the MPAC are illustrated with epidemiological data.

Predicting HIV disease progression in children using measures of neuropsychological and neurological functioning. Pediatric AIDS clinical trials 152 study team

BACKGROUND

Neuropsychological testing and 2 measures of neurological status, cortical atrophy, and motor dysfunction were assessed for their usefulness in predicting human immunodeficiency virus (HIV) disease progression in infants, children, and adolescents who participated in Pediatric AIDS Clinical Trials Group Protocol 152 (PACTG 152).

METHODS

A cohort of 722 antiretroviral therapy-naive children with symptomatic HIV infection were assessed at study entry and at later intervals. Assessments included neurodevelopmental testing, neuroradiologic imaging, and neurological examination of motor function. CD4 cell count and plasma RNA viral load also were measured.

RESULTS

Children with the lowest neuropsychological functioning (IQ < 70) at baseline had the highest risk for later HIV disease progression (56%), compared with those with borderline/low (IQ = 70-89) functioning (26%), or with average or above (IQ > 90) functioning (18%). This was also true of week 48 neuropsychological functioning. Motor dysfunction (especially reduced muscle mass) at entry also predicted disease progression. Furthermore, motor dysfunction and week 48 neuropsychological functioning provided predictive information beyond that obtainable from surrogate markers of HIV disease status (eg, CD4 count, HIV RNA level). Children with cortical atrophy also were at higher risk for later disease progression, but when CD4 count and RNA viral load were known, cortical atrophy information provided no additional predictive information.

CONCLUSIONS

Measures of neuropsychological and motor function status provide unique information regarding pediatric HIV disease progression. As such, these findings have important implications for predicting long-term outcomes (eg, longevity) in pediatric patients.

Metal substitution in transferrins: specific binding of cerium(IV) revealed by the crystal structure of cerium-substituted human lactoferrin

Proteins of the transferrin family play a key role in iron homeostasis through their extremely strong binding of iron, as Fe3+. They are nevertheless able to bind a surprisingly wide variety of other metal ions. To investigate how metal ions of different size, charge and coordination characteristics are accommodated, we have determined the crystal structure of human lactoferrin (Lf) complexed with Ce4+. The structure, refined at 2.2 A resolution (R=20.2%, Rfree=25.7%) shows that the two Ce4+ ions occupy essentially the same positions as do Fe3+, and that the overall protein structure is unchanged; the same closed structure is formed for Ce2Lf as for Fe2Lf. The larger metal ion is accommodated by small shifts in the protein ligands, made possible by the presence of water molecules adjacent to each binding site. The two Ce4+ sites are equally occupied, indicating that the known difference in the pH-dependent release of Ce4+ arises from a specific protonation event, possibly of the His ligand in one of the binding sites. Comparing the effects of binding Ce4+ with those for the binding of other metal ions, we conclude that the ability of transferrins to accommodate metal ions other than Fe3+ depends on an interplay of charge, size, coordination and geometrical preferences of the bound metal ion. However, it is the ability to accept the six-coordinate, approximately octahedral, site provided by the protein that is of greatest importance.

Treatment-mediated changes in human immunodeficiency virus (HIV) type 1 RNA and CD4 cell counts as predictors of weight growth failure, cognitive decline, and survival in HIV-infected children

This meta-analysis of 5 large studies of the Pediatric AIDS Clinical Trials Group was undertaken to evaluate the predictive value of antiretroviral treatment-mediated changes in 3 markers of human immunodeficiency virus (HIV) type 1 disease progression-HIV-1 RNA level, CD4 cell count, and CD4 percentage-for weight growth failure, cognitive decline, and survival in HIV-infected children. Proportional hazards models were used to assess the prognostic value of the markers at baseline and after 24 weeks of treatment, with data from 1089 children. Among children receiving nucleoside with or without nonnucleoside reverse-transcriptase inhibitors, higher immunologic and lower virologic markers at baseline and after 24 weeks were significant independent predictors of survival, whereas virologic markers were significant predictors of weight growth and cognitive failure in children >1 year old. The finding of differential age effects on pediatric-specific clinical outcomes emphasizes the need for continued investigation of treatment effects in children.

Modulation of pulmonary NA+ pump gene expression during cold storage and reperfusion

BACKGROUND

Reperfusion injury with pulmonary edema continues to be a major complication after lung transplantation. Alveolar fluid homeostasis is regulated by Na+/K+-ATPase activity on the basolateral surface of alveolar epithelial cells. Intact Na+/K+-ATPase is essential to the resolution of pulmonary edema. We characterized the effects of cold ischemia and reperfusion on expression of Na+/K+-ATPase mRNA and protein.

METHODS

Baseline values for Na+/K+-ATPase mRNA and protein were determined from freshly harvested lungs with no cold storage time or reperfusion (group I). Group II lungs were analyzed after cold storage times of 12 or 24 hr without subsequent reperfusion. Group III lungs were analyzed after cold storage times of 12 or 24 hr with subsequent reperfusion. Lungs were flushed with either Euro-Collins (EC) or University of Wisconsin (UW) solution in each group. All samples were quantified for Na+/K+-ATPase mRNA and Na+/K+-ATPase protein. Physiological parameters including oxygenation and compliance were also measured.

RESULTS

There were no significant differences in the level of mRNA and protein for samples that were cold stored without reperfusion (group II). With reperfusion (group III) there was a significant increase in the level of the Na+/K+-ATPase mRNA after 12 hr of storage for both EC and UW. After 24 hr of storage and subsequent reperfusion, lungs flushed with EC had significantly decreased Na+/K+-ATPase protein and mRNA, although lungs preserved with UW maintained their increased levels of Na+/K+-ATPase protein and mRNA.

CONCLUSIONS

Our data suggest that ischemia-reperfusion injury results in an initial up-regulation of Na+/K+-ATPase mRNA. With prolonged injury in lungs preserved with EC, the level of the mRNA decreased with a corresponding decrease in the Na+/K+-ATPase protein. The different response seen in EC versus UW may be explained by better preservation of pump function with UW than EC and correlates with improved physiological function in lungs preserved with UW solution.

Scavenging of H2O2 and production of oxygen by horseradish peroxidase

Peroxidases catalyze many reactions, the most common being the utilization of H2O2 to oxidize numerous substrates (peroxidative mode). Peroxidases have also been proposed to produce H2O2 via utilization of NAD(P)H, thus providing oxidant either for the first step of lignification or for the "oxidative burst" associated with plant-pathogen interactions. The current study with horseradish peroxidase characterizes a third type of peroxidase activity that mimics the action of catalase; molecular oxygen is produced at the expense of H2O2 in the absence of other reactants. The oxygen production and H2O2-scavenging activities had temperature coefficients, Q10, of nearly 3 and 2, which is consistent with enzymatic reactions. Both activities were inhibited by autoclaving the enzyme and both activities had fairly broad pH optima in the neutral-to-alkaline region. The apparent Km values for the oxygen production and H2O2-scavenging reactions were near 1.0 mM H2O2. Irreversible inactivation of horseradish peroxidase by exposure to high concentrations of H2O2 coincided with the formation of an absorbance peak at 670 nm. Addition of superoxide dismutase (SOD) to reaction mixtures accelerated the reaction, suggesting that superoxide intermediates were involved. It appears that horseradish peroxidase is capable of using H2O2 both as an oxidant and as a reductant. A model is proposed and the relevance of the mechanism in plant-bacterial systems is discussed.

Use of capsular polysaccharide-tetanus toxoid conjugate vaccine for type II group B Streptococcus in healthy women

An estimated 15% of invasive group B streptococcal (GBS) disease is caused by type II capsular polysaccharide (II CPS). In developing a pentavalent vaccine for the prevention of GBS infections, individual GBS CPSs have been coupled to tetanus toxoid (TT) to prepare vaccines with enhanced immunogenicity. Type II GBS (GBS II) vaccine was created by direct, covalent coupling of II CPS to TT by reductive amination. In 2 clinical trials, 75 healthy nonpregnant women 18-45 years old were randomized to receive II CPS-TT (II-TT) conjugate (dose range, 3.6-57 microg of CPS component) or uncoupled II CPS vaccine. Both vaccines were well tolerated. II CPS-specific IgG serum concentrations (as well as IgM and IgA) peaked 2 weeks after immunization, being significantly higher in recipients of conjugated vaccine than in recipients of uncoupled CPS. Immunological responses to conjugate were dose dependent and correlated with opsonophagocytosis in vitro. These results support inclusion of II-TT conjugate when preparing a multivalent GBS vaccine.

Group B streptococcal colonization and serotype-specific immunity in pregnant women at delivery

OBJECTIVE

To describe the relationship between serum concentration of group B streptococcal capsular polysaccharide-specific immunoglobulin (Ig) G, colonization status, race or ethnicity, and age in pregnant women.

METHODS

Pregnant women (n = 3307) were enrolled from geographically and ethnically diverse populations. At the time of admission for delivery, swabs of the lower vagina and rectum were obtained for isolation of group B streptococci. In a subset of women whose sera were available, capsular polysaccharide-specific IgG concentrations were quantified by serotype-specific (Ia, Ib, II, III, and V) enzyme-linked immunosorbent assay and compared by group B streptococcal colonization status.

RESULTS

Group B streptococcal colonization was detected in 856 women (26%), and the rate was significantly higher among black women (37%) than in other racial or ethnic groups (odds ratio 1.7, 95% confidence interval 1.4, 2.1). Colonization status did not differ by study site or age. Colonization with serotypes Ia, II, III, or V was associated with significantly higher serum concentrations of IgG specific for the capsular polysaccharide of the colonizing serotype compared with noncolonization. However, 48% of colonized women had low capsular polysaccharide-specific IgG levels (less than 0.5 microg/mL) in their delivery sera. Colonized teenagers had the lowest median concentration.

CONCLUSION

Colonization with group B streptococcus can elicit a systemic immune response, with a cumulative increase in the prevalence of capsular polysaccharide-specific IgG with increasing age. Conversely, low antibody levels in colonized teenagers might account in part for the reported increased risk of group B streptococcal disease in neonates born to these patients.

Candidal meningitis in neonates: a 10-year review

Candidal meningitis may complicate systemic candidiasis in the premature neonate. We conducted a 10-year retrospective review of 106 cases of systemic candidiasis in neonates to define the incidence, clinical features, laboratory findings, treatment, and outcome of candidal meningitis. Twenty-three of the 106 neonates had candidal meningitis (0.4% of admissions to the neonatal intensive care unit). The median gestational age was 26.2 weeks, the median birth weight was 820 g, and the median age at the onset of illness was 8 days. Clinical disease was severe and commonly was manifested by respiratory decompensation. Findings of cerebrospinal fluid (CSF) analyses varied: pleocytosis was inconsistent, hypoglycorrhachia was common, gram staining was uniformly negative, and Candida was isolated from 17 neonates (74%). Each infant was treated with amphotericin B (median cumulative dose, 30 mg/kg); 5 also received flucytosine therapy. In conclusion, initial clinical features of candidal meningitis are indistinguishable from those of other causes of systemic infection in premature neonates, and normal CSF parameters do not exclude meningitis. Timely initiation of amphotericin B monotherapy was associated with an excellent outcome.

The CCR5Delta32 allele slows disease progression of human immunodeficiency virus-1-infected children receiving antiretroviral treatment

The role of the CCR5Delta32 allele in human immunodeficiency virus (HIV)-1-related disease progression was analyzed for 457 antiretroviral-naïve children who had participated in the Pediatric AIDS Clinical Trials Group 152 study, which demonstrated that didanosine (ddI) or zidovudine + ddI treatments were superior to zidovudine alone. The CCR5Delta32 allele was detected at an overall frequency of 6.1% (28/457). At study entry, heterozygote children (wild type [wt]/Delta32) had higher baseline median CD4(+) counts/mm(3) than wt/wt children had (1035 vs. 835 cells/mm(3); P=. 043), higher mean weight-for-age Z scores (-0.15 vs. -0.84; P=.01), and a trend toward less cortical atrophy (P=.059). During antiretroviral treatment and study follow-up, there was a trend toward less disease progression and death among heterozygote children than among wt/wt children (P=.056; relative hazard, 0.28; 95% confidence interval, 0.07-1.13) independent of the antiretroviral treatment to which they were randomized.

Platelet activating factor acetylhydrolase decreases lung reperfusion injury

BACKGROUND

Ischemia-reperfusion injury involves free radical production, polymorphonuclear neutrophil chemotaxis/degranulation, and production of proteolytic enzymes, complement components, coagulation factors, and cytokines. Activated polymorphonuclear neutrophils, endothelial cells, and macrophages produce platelet activating factor, which further promotes these inflammatory reactions. The recently cloned plasma form of platelet activating factor-acetylhydrolase (PAF-AH) demonstrates antiinflammatory effects by degrading platelet activating factor. We evaluated the effects of PAF-AH in an isolated perfused rat lung model by adding it to the flush solutions or to the reperfusion blood.

METHODS

Rat lungs were isolated, flushed with EuroCollins (EC) or University of Wisconsin (UW) solution, stored at 4 degrees C for 6 or 12 hours, and reperfused using a cross-circulating syngeneic support rat. During reperfusion, oxygenation, compliance, and capillary filtration coefficient were calculated. There were four groups in the study; group I (control) had no PAF-AH added, group II had PAF-AH added to the flush solution, group III had PAF-AH added to reperfusion blood, and group IV had PAF-AH added to both flush solution and reperfusion blood.

RESULTS

After 6 hours of storage, oxygenation, compliance, and capillary filtration coefficient significantly improved for EC in group IV. For UW, oxygenation improved in group IV whereas compliance improved in groups II, III, and IV. After 12 hours of storage, compliance improved for EC in group IV and capillary filtration coefficient improved in groups III and IV. For UW, oxygenation and compliance improved in groups II and IV, whereas capillary filtration coefficient improved in group IV.

CONCLUSIONS

Addition of PAF-AH to intracellular organ preservation solutions and to the blood reperfusate significantly improves postreperfusion oxygenation and compliance, and reduces lung capillary permeability.

Discitis and vertebral osteomyelitis in children: an 18-year review

BACKGROUND

Discitis and vertebral osteomyelitis are uncommon entities, and diagnosis often is confounded by their similar clinical presentation, because characteristic radiographic findings are not evident until late in the course of illness.

OBJECTIVE

To compare the age distribution, clinical manifestations, and radiographic findings, especially magnetic resonance imaging (MRI), in children with discitis or vertebral osteomyelitis.

METHODS

A retrospective review of 57 children with a discharge diagnosis of discitis or vertebral osteomyelitis hospitalized from January 1980 through December 1998.

RESULTS

Fifty patients met inclusion criteria: 36 with discitis and 14 with vertebral osteomyelitis. The mean age at presentation was younger for children with discitis than for those with vertebral osteomyelitis (2.8 vs 7.5 years of age) and the duration of symptoms longer for children with vertebral osteomyelitis than for those with discitis (33 vs 22 days). The initial symptom for both groups of children was refusal to walk, limp, or back pain, but children with osteomyelitis more often were febrile (79% vs 28%) and ill-appearing than those with discitis. Thirty-three patients with discitis had radiographs of the spine; 25 (76%) had abnormalities that were diagnostic. Ten discitis patients had MRI; 9 (90%) had abnormalities consistent with this diagnosis. Thirteen children with vertebral osteomyelitis had radiographs of the spine, but in only 7 (54%) were these abnormal. However, 11 had MRIs, and in each the diagnosis of vertebral osteomyelitis was established.

CONCLUSION

This comparative study suggests that age and clinical presentation distinguish most patients with discitis from those with vertebral osteomyelitis. Although radiographs of the spine usually are sufficient to establish the diagnosis of discitis, MRI is the diagnostic study of choice for pediatric patients with suspected vertebral osteomyelitis.

Systemic candidiasis in extremely low birth weight infants receiving topical petrolatum ointment for skin care: a case-control study

BACKGROUND AND OBJECTIVE

An increase in the incidence of systemic candidiasis (SC) followed a change in skin care for extremely low birth weight (ELBW) infants in our neonatal intensive care unit (NICU). We sought to determine whether the use of topical petrolatum ointment (TPO) for skin care of ELBW infants was associated with risk for SC.

STUDY DESIGN

Case-control study.

SETTING

A 48-bed NICU in a private hospital in Houston, Texas.

PATIENTS

Ten ELBW infants with and 30 without SC admitted to the NICU from December 1, 1997 through July 31, 1998.

METHODS

ELBW infants with SC were identified using hospital microbiology and infectious disease consultation databases. A case was defined as an infant weighing </=1000 g at birth with Candida spp isolated from a normally sterile body site. Three infants without SC were matched to each case by birth weight, admission date, and survival to the age of SC onset for the case. Data were collected by retrospective medical record review. Molecular analysis of Candida isolates was performed by karyotyping and restriction fragment length polymorphism using pulsed-field gel electrophoresis.

RESULTS

Case infants had a mean (+/- standard deviation) age of onset of 21.5 +/- 24 days. Infants with SC and controls did not differ in birth weight, gestational age, or duration of therapy with steroids, antibiotics, insulin, or total parenteral nutrition. Although cases were more likely to be born vaginally and had a longer duration endotracheal intubation than controls, these differences were not significant. The odds ratio for skin care with TPO in case infants versus control infants was 11 (95% confidence interval: 1.9-63). Skin care with TPO was discontinued and the incidence of SC decreased to baseline. Several Candida spp and genetic profiles were identified, suggesting that there was not a common source outbreak.

CONCLUSIONS

We conclude that the use of TPO promoted an increase in the incidence of SC in ELBW infants. Additional investigation of potential infectious risks for ELBW infants receiving TPO skin care is warranted.