Residual risk of transmission of HIV through blood transfusion in South Africa

Despite the ongoing review of donor recruitment criteria by local blood transfusion services and the developmnt of highly sensitive and specific testing for the presence of antibodies to HIV in blood and blood products, there remains a residue of HIV in donated blood. This is because of donors who are in the 'window period' between acquisition of HIV and seroconversion, human errors and limits to the sensitivity and specificity of current tests. Data available from a national survey of HIV seroprevalence in South African blood donors allowed for the estimation of the number of units screened negative but likely to be infected with HIV. Assuming window periods of 4,8 and 14 weeks, a test sensitivity of 99,9%, a specificity of 98,5% and a human error rate of 0,1%, the likely rate of HIV-infected blood in the South African blood transfusion supply ranges from 1,1 to 3,9/ 100 000 units, with a likely estimate of 2,2/100 000 units. In the current South African blood transfusion setting, between 8,1 and 28,2 units of blood per annum. will be HIV-positive with a likely estimate of 15,9 units. This corresponds to an odds ratio of between 1:90 909 and 1:25 641 units infected with HIV. These data are comparable with the risk in developed countries. The expected increase in the incidence and prevalence of HIV infection in all adult South African populations necessitates additional measures to ensure a blood supply which is as safe as possible. Some of these measures have already been taken by local blood transfusion services

J/Psi Production from Electromagnetic Fragmentation in Z decay

The rate for $Z^{0}\to J/ \psi + \ell^{+}\ell^{-}$ is suprisingly large with about one event for every million $Z^{0}$ decays. The reason for this is that there is a fragmentation contribution that is not suppressed by a factor of $M^{2}_{\psi}/M^{2}_{Z}$. In the fragmentation limit $M_{Z}\to\infty$ with $E_{\psi}/M_{Z}$ fixed, the differential decay rate for $Z^{0}\to J/ \psi + \ell^{+}\ell^{-}$ factors into electromagnetic decay rates and universal fragmentation functions. The fragmentation functions for lepton fragmentation and photon fragmentation into $J/\psi$ are calculated to lowest order in $\alpha$. The fragmentation approximation to the rate is shown to match the full calculation for $E_{\psi}$ greater than about $3 M_{\psi}$.Comment: 16 pages and 8 figure

Structure and properties of a novel fulleride Sm6C60

A novel fulleride Sm6C60 has been synthesized using high temperature solid state reaction. The Rietveld refinement on high resolution synchrotron X-ray powder diffraction data shows that Sm6C60 is isostructural with body-centered cubic A6C60 (A=K, Ba). Raman spectrum of Sm6C60 is similar to that of Ba6C60, and the frequencies of two Ag modes in Sm6C60 are nearly the same as that of Ba6C60, suggesting that Sm is divalent and hybridization between C60 molecules and the Sm atom could exist in Sm6C60. Resistivity measurement shows a weak T-linear behavior above 180 K, the transport at low temperature is mainly dominated by granular-metal theory.Comment: 9 pages, 3 figures, submitted to Phys. Rev. B (March 12, 1999

Insulating and Conducting Phases of RbC60

Optical measurements were performed on thin films of Rb$_{x}$C$_{60}$, identified by X-ray diffraction as mostly $x=1$ material. The samples were subjected to various heat treatments, including quenching and slow cooling from 400K. The dramatic increase in the transmission of the quenched samples, and the relaxation towards the transmission observed in slow cooled samples provides direct evidence for the existence of a metastable insulating phase. Slow cooling results in a phase transition between two electrically conducting phases.Comment: Minor revisions. Submitted to PRB, RevTeX 3.0 file, 2 postscript figures included, ir_dop

Structural and electronic properties of (NH3)xK3C60

We have investigated the synthesis, structure, and electronic properties of (NH3)xK3C60 by exposing preformed K3C60 to NH3 vapor. Measurements were made on bulk powders and films with a variety of techniques including in-situ x-ray diffraction and monitoring of NH3 pressure, Raman scattering and ac susceptibility. The reaction of NH3 with K3C60 is completely reversible and leaves the (C60)3- charge state intact, while allowing the distance between the C60 molecules to vary. We observe two different crystallographic structures at x=1 and x=8-10. The x=1 structure is face-centered orthorhombic with a single NH3 on the octahedral interstitial site. It is single phase at 100°C and NH3 pressures 400 torr and remains single phase at 0 torr if the temperature is reduced to 25°C. Although (NH3)K3C60 exhibits no superconductivity at ambient pressure, superconductivity can be induced by hydrostatic pressure with an onset at 28 K. The details of the x=8-10 structure are uncertain, however it appears that this phase is body-centered tetragonal with NH3 on both the octahedral and tetrahedral sites. It occurs at room temperature and NH3 pressures 500 torr, but is not stable at lower NH3 pressures. Resistivity measurements of NH3-doped K3C60 films show that the formation of the new structure results in a rapid increase of the resistivity to values exceeding 1 cm

Electron-phonon interaction in C70

The matrix elements of the deformation potential of C$_{70}$ are calculated by means of a simple, yet accurate solution of the electron-phonon coupling problem in fullerenes, based on a parametrization of the ground state electronic density of the system in terms of $sp^{2+x}$ hybridized orbitals. The value of the calculated dimensionless total electron-phonon coupling constant is $\lambda\approx0.1$, an order of magnitude smaller than in C$_{60}$, consistent with the lack of a superconducting phase transition in C$_{70}$A$_3$ fullerite, and in overall agreement with measurements of the broadening of Raman peaks in C$_{70}$K$_4$. We also calculate the photoemission cross section of C$_{70}^-$, which is found to display less structure than that associated with C$_{60}^-$, in overall agreement with the experimental findings.Comment: To be published in Phys. Rev.

Hepatocyte growth factor pathway expression in breast cancer by race and subtype

Background: African American women have the highest risk of breast cancer mortality compared to other racial groups. Differences in tumor characteristics have been implicated as a possible cause; however, the tumor microenvironment may also contribute to this disparity in mortality. Hepatocyte growth factor (HGF) is a stroma-derived marker of the tumor microenvironment that may affect tumor progression differentially by race. Objective: To examine whether an HGF gene expression signature is differentially expressed by race and tumor characteristics. Methods: Invasive breast tumors from 1957 patients were assessed for a 38-gene RNA-based HGF gene expression signature. Participants were black (n = 1033) and non-black (n = 924) women from the population-based Carolina Breast Cancer Study (1993–2013). Generalized linear models were used to estimate the relative frequency differences (RFD) in HGF status by race, clinical, and demographic factors. Results: Thirty-two percent of tumors were positive for the HGF signature. Black women were more likely [42% vs. 21%; RFD = + 19.93% (95% CI 16.00, 23.87)] to have HGF-positive tumors compared to non-black women. Triple-negative patients had a higher frequency of HGF positivity [82% vs. 13% in non-triple-negative; RFD = + 65.85% (95% CI 61.71, 69.98)], and HGF positivity was a defining feature of basal-like subtype [92% vs. 8% in non-basal; RFD = + 81.84% (95% CI 78.84, 84.83)]. HGF positivity was associated with younger age, stage, higher grade, and high genomic risk of recurrence (ROR-PT) score. Conclusion: HGF expression is a defining feature of basal-like tumors, and its association with black race and young women suggests it may be a candidate pathway for understanding breast cancer disparities

Counting the bodies: Estimating the numbers and spatial variation of Australian reptiles, birds and mammals killed by two invasive mesopredators

Aim Introduced predators negatively impact biodiversity globally, with insular fauna often most severely affected. Here, we assess spatial variation in the number of terrestrial vertebrates (excluding amphibians) killed by two mammalian mesopredators introduced to Australia, the red fox (Vulpes vulpes) and feral cat (Felis catus). We aim to identify prey groups that suffer especially high rates of predation, and regions where losses to foxes and/or cats are most substantial. Location Australia. Methods We draw information on the spatial variation in tallies of reptiles, birds and mammals killed by cats in Australia from published studies. We derive tallies for fox predation by (i) modelling continental-scale spatial variation in fox density, (ii) modelling spatial variation in the frequency of occurrence of prey groups in fox diet, (iii) analysing the number of prey individuals within dietary samples and (iv) discounting animals taken as carrion. We derive point estimates of the numbers of individuals killed annually by foxes and by cats and map spatial variation in these tallies. Results Foxes kill more reptiles, birds and mammals (peaking at 1071 km−2 year−1) than cats (55 km−2 year−1) across most of the unmodified temperate and forested areas of mainland Australia, reflecting the generally higher density of foxes than cats in these environments. However, across most of the continent – mainly the arid central and tropical northern regions (and on most Australian islands) – cats kill more animals than foxes. We estimate that foxes and cats together kill 697 million reptiles annually in Australia, 510 million birds and 1435 million mammals. Main conclusions This continental-scale analysis demonstrates that predation by two introduced species takes a substantial and ongoing toll on Australian reptiles, birds and mammals. Continuing population declines and potential extinctions of some of these species threatens to further compound Australia's poor contemporary conservation record

‘I can die today, I can die tomorrow’: lay perceptions of sickle cell disease in Kumasi, Ghana at a point of transition

Objective. To describe the lay meanings of sickle cell disease (SCD) in the Ashanti region of Ghana

Racial differences in breast cancer outcomes by hepatocyte growth factor pathway expression

Purpose: Black women have a 40% increased risk of breast cancer-related mortality. These outcome disparities may reflect differences in tumor pathways and a lack of targetable therapies for specific subtypes that are more common in Black women. Hepatocyte growth factor (HGF) is a targetable pathway that promotes breast cancer tumorigenesis, is associated with basal-like breast cancer, and is differentially expressed by race. This study assessed whether a 38-gene HGF expression signature is associated with recurrence and survival in Black and non-Black women. Methods: Study participants included 1957 invasive breast cancer cases from the Carolina Breast Cancer Study. The HGF signature was evaluated in association with recurrence (n = 1251, 171 recurrences), overall, and breast cancer-specific mortality (n = 706, 190/328 breast cancer/overall deaths) using Cox proportional hazard models. Results: Women with HGF-positive tumors had higher recurrence rates [HR 1.88, 95% CI (1.19, 2.98)], breast cancer-specific mortality [HR 1.90, 95% CI (1.26, 2.85)], and overall mortality [HR 1.69; 95% CI (1.17, 2.43)]. Among Black women, HGF positivity was significantly associated with higher 5-year rate of recurrence [HR 1.73; 95% CI (1.01, 2.99)], but this association was not significant in non-Black women [HR 1.68; 95% CI (0.72, 3.90)]. Among Black women, HGF-positive tumors had elevated breast cancer-specific mortality [HR 1.80, 95% CI (1.05, 3.09)], which was not significant in non-Black women [HR 1.52; 95% CI (0.78, 2.99)]. Conclusion: This multi-gene HGF signature is a poor-prognosis feature for breast cancer and may identify patients who could benefit from HGF-targeted treatments, an unmet need for Black and triple-negative patients