Gametocyte carriage in Plasmodium falciparum-infected travellers.

BACKGROUND: Gametocytes are the sexual stage of Plasmodium parasites. The determinants of gametocyte carriage have been studied extensively in endemic areas, but have rarely been explored in travellers with malaria. The incidence of gametocytaemia, and factors associated with gametocyte emergence in adult travellers with Plasmodium falciparum malaria was investigated at the Hospital for Tropical Diseases in London. METHODS: Clinical, parasitological and demographic data for all patients presenting with P. falciparum malaria between January 2001 and December 2011 were extracted from a prospective database. These data were supplemented by manual searches of laboratory records and patient case notes. RESULTS: Seven hundred and seventy three adult patients with laboratory-confirmed P. falciparum malaria were identified. Four hundred and sixty five (60%) were born in a country where malaria is endemic. Patients presented to hospital a median of four days into their illness. The median maximum parasite count was 0.4%. One hundred and ninety six patients (25%) had gametocytes; 94 (12%) on admission, and 102 (13%) developing during treatment. Gametocytaemia on admission was associated with anaemia and a lower maximum parasitaemia. Patients with gametocytes at presentation were less likely to have thrombocytopenia or severe malaria. Patients who developed gametocytes during treatment were more likely to have had parasitaemia of long duration, a high maximum parasitaemia and to have had severe malaria. There was no apparent association between the appearance of gametocytes and treatment regimen. CONCLUSIONS: The development of gametocytaemia in travellers with P. falciparum is associated with factors similar to those reported among populations in endemic areas. These data suggest that acquired immunity to malaria is not the only determinant of patterns of gametocyte carriage among patients with the disease

Delayed diagnosis of neuroschistosomiasis in a non-endemic country: A tertiary referral centre experience

BACKGROUND: Neuroschistosomiasis is a severe complication of schistosomiasis, triggered by the local immune reaction to egg deposition, with spinal cord involvement the most well recognised form. Early treatment with praziquantel and high dose steroids leads to a reduction of neurological sequelae. The rarity of this condition in returning travellers to high income countries can result in delayed diagnosis and treatment. We aimed to evaluate the diagnosis and management of neuroschistosomiasis in a UK national referral centre. MATERIALS AND METHODS: A retrospective review of confirmed clinical cases of spinal schistosomiasis referred to the Hospital for Tropical Diseases, UK, between January 2016 and January 2020 was undertaken. Electronic referral records were interrogated and patient demographic, clinical, laboratory, and radiological data collected. RESULTS: Four cases of neuroschistosomiasis were identified. The median age at diagnosis was 28 (range 21 to 50) with three male patients. All patients had epidemiological risk factors for schistosomiasis based on travel history and freshwater exposure; two in Uganda (River Nile), one in Malawi and one in Nigeria. All patients presented with features of transverse myelitis including back pain, leg weakness, paraesthesia and urinary dysfunction. The mean time from presentation to health services to definitive treatment was 42.5 days (range 16–74 days). Diagnosis was confirmed with CSF serology for schistosomiasis in all cases. Radiological features on MRI spine included enhancement focused predominantly in the lower thoracic spinal cord in three cases and the conus in one patient. All patients received a minimum of three days of oral praziquantel and high dose steroids. At three-month follow-up, one patient had complete resolution of symptoms and three had residual deficit; one patient was left with urinary and faecal incontinence, another had urinary retention, and the final patient has persistent leg pains and constipation. CONCLUSION: We observed a marked delay in diagnosis of neuroschistosomiasis in a non-endemic country. We advocate undertaking a thorough travel history, early use of imaging and CSF schistosomal serology to ensure early diagnosis of neuroschistosomiasis in patients presenting with consistent symptoms. If schistosomal diagnostics are not immediately available, presumptive treatment under the guidance of a tropical medicine specialist should be considered to minimize the risk of residual disability. We advocate for consensus guidelines to be produced and reporting to be performed in a uniform way for patients with spinal schistosomiasis

Stability of Ge-related point defects and complexes in Ge-doped SiO_2

We analyze Ge-related defects in Ge-doped SiO_2 using first-principles density functional techniques. Ge is incorporated at the level of ~ 1 mol % and above. The growth conditions of Ge:SiO_2 naturally set up oxygen deficiency, with vacancy concentration increasing by a factor 10^5 over undoped SiO_2, and O vacancies binding strongly to Ge impurities. All the centers considered exhibit potentially EPR-active states, candidates for the identification of the Ge(n) centers. Substitutional Ge produces an apparent gap shrinking via its extrinsic levels.Comment: RevTeX 4 pages, 2 ps figure

Beam Test Results of the BTeV Silicon Pixel Detector

The results of the BTeV silicon pixel detector beam test carried out at Fermilab in 1999-2000 are reported. The pixel detector spatial resolution has been studied as a function of track inclination, sensor bias, and readout threshold.Comment: 8 pages of text, 8 figures, Proceedings paper of Pixel 2000: International Workshop on Semiconductor Pixel Detectors for Particles and X-Rays, Genova, June 5-8, 200

Adrenal Hypercortisolism: A Closer Look at Screening, Diagnosis, and Important Considerations of Different Testing Modalities

Although prolonged hypercortisolism is associated with increased mortality and substantial morbidity, the clinical signs and symptoms are wide ranging and often nonspecific, contributing to challenges in diagnosis, as well as treatment delays. Greater awareness is needed among clinicians to help identify which patients should undergo biochemical screening for excess cortisol. Several biochemical tests are available, each with important caveats that should be considered in the context of the individual patient. Cortisol secretion varies widely, further complicating the biochemical diagnosis of hypercortisolism, which relies on the use of definitive cutoff values. Patients with hypercortisolism resulting from adrenal adenomas, including those discovered incidentally, often do not present with overt Cushingoid features (plethora, striae, muscle weakness, moon facies, etc.). However, the consequences of prolonged exposure to even slight elevations in cortisol levels are profound, including increased risk of diabetes, hypertension, fractures, cardiovascular events, and mortality. Because most cases of hypercortisolism resulting from an adrenal adenoma can be managed, it is imperative to identify patients at risk and initiate testing early for the best outcomes. The aim of this report is to increase awareness of the indications for screening for hypercortisolism and to review the biochemical screening tests and diagnosis for hypercortisolism associated with adrenal adenomas

Performance of prototype BTeV silicon pixel detectors in a high energy pion beam

The silicon pixel vertex detector is a key element of the BTeV spectrometer. Sensors bump-bonded to prototype front-end devices were tested in a high energy pion beam at Fermilab. The spatial resolution and occupancies as a function of the pion incident angle were measured for various sensor-readout combinations. The data are compared with predictions from our Monte Carlo simulation and very good agreement is found.Comment: 24 pages, 20 figure

Beam Test of BTeV Pixel Detectors

The silicon pixel vertex detector is one of the key elements of the BTeV spectrometer. Detector prototypes were tested in a beam at Fermilab. We report here on the measured spatial resolution as a function of the incident angles for different sensor-readout electronics combinations. We compare the results with predictions from our Monte Carlo simulation.Comment: 7 pages, 5 figures, Invited talk given by J.C. Wang at "Vertex 2000, 9th International Workshop on Vertex Detectors", Michigan, Sept 10-15, 2000. To be published in NIM

Ambient Seismic Noise Image of the Structurally Controlled Heat and Fluid Feeder Pathway at Campi Flegrei Caldera

The TIDES-COST Action (STSM-ES1401-34011) provided a travel grant to framework the research project. The Japan Society for the Promotion of Science - Short-Term Fellowship (JSPS/OF215/022) financed the work, undertaken at Tohoku University and concluded at the University of Aberdeen. We thank Giuseppe Vilardo and Eliana Bellucci Sessa for providing the geomorphological maps, and Simona Petrosino and Paola Cusano for the P- and S-wave pickings used to localise the seismicity. Informal revisions from Guido Ventura, Nick Rawlinson and Chris Kilburn helped us improving the analyses and interpretation, respectively. We acknowledge the help of Naveed Khan in parallelising the codes and two anonymous reviewers who improved the analysis, interpretation, and readibility with their comments. All data to reproduce the maps can be downloaded from the World Data Center PANGAEA data repository, permanent link https://doi.pangaea.de/10.1594/PANGAEA.890238.Peer reviewedPublisher PD

A Measurement of the Ds+ Lifetime

A high statistics measurement of the Ds+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis of the two decay modes, Ds+ -> phi(1020)pi+ and Ds+ -> \bar{K}*(892)0K+, used for the measurement. The measured lifetime is 507.4 +/- 5.5 (stat.) +/- 5.1 (syst.) fs using 8961 +/- 105 Ds+ -> phi(1020)pi+ and 4680 +/- 90 Ds+ -> \bar{K}*(892)0K+ decays. This is a significant improvement over the present world average.Comment: 5 pages, 3 figures, 2 tables, submitted to PR

Assessing the safety of cosmetic chemicals: Consideration of a flux decision tree to predict dermally delivered systemic dose for comparison with oral TTC (Threshold of Toxicological Concern)

AbstractThreshold of Toxicological Concern (TTC) aids assessment of human health risks from exposure to low levels of chemicals when toxicity data are limited. The objective here was to explore the potential refinement of exposure for applying the oral TTC to chemicals found in cosmetic products, for which there are limited dermal absorption data. A decision tree was constructed to estimate the dermally absorbed amount of chemical, based on typical skin exposure scenarios. Dermal absorption was calculated using an established predictive algorithm to derive the maximum skin flux adjusted to the actual ‘dose’ applied. The predicted systemic availability (assuming no local metabolism), can then be ranked against the oral TTC for the relevant structural class. The predictive approach has been evaluated by deriving the experimental/prediction ratio for systemic availability for 22 cosmetic chemical exposure scenarios. These emphasise that estimation of skin penetration may be challenging for penetration enhancing formulations, short application times with incomplete rinse-off, or significant metabolism. While there were a few exceptions, the experiment-to-prediction ratios mostly fell within a factor of 10 of the ideal value of 1. It can be concluded therefore, that the approach is fit-for-purpose when used as a screening and prioritisation tool