A British Society for Haematology Guideline: Diagnosis and management of thrombotic thrombocytopenic purpura and thrombotic microangiopathies

The objective of this guideline is to provide healthcare professionals with clear, up-to-date and practical guidance on the management of thrombotic thrombocytopenic purpura (TTP) and related thrombotic microangiopathies (TMAs), including complement-mediated haemolytic uraemic syndrome (CM HUS); these are defined by thrombocytopenia, microangiopathic haemolytic anaemia (MAHA) and small vessel thrombosis. Within England, all TTP cases should be managed within designated regional centres as per NHSE commissioning for highly specialised services.

Accidental lipid overdose in a preterm infant: A case report

BACKGROUND

Intravenous lipid emulsions (ILEs) provide essential fatty acids during parenteral nutrition (PN). Serious adverse events including death can occur from overdose. We report an accidental overdose in a preterm infant.

METHOD

On Day 2 of life, a 29-week gestational age (GA) twin was accidentally given 47.5 mL of Intralipid20% (≈3x daily amount) in 50-minutes.

RESULTS

No apparent clinical deterioration occurred, although blood samples were lipaemic. Outcomes at 2 years corrected GA were similar to that of his twin. Service changes were made to infusion packaging and administration to avoid similar errors.

CONCLUSIONS

Medication errors in neonates are unfortunately common. Published articles usually focus on poor outcomes, which can increase the distress for parents of children where errors have occurred. Publishing the full spectrum of outcomes instead allows parents and professionals to be aware of all possibilities and lessons learnt, even if serious harm was avoided.

Measurements of Argon-39 from locations near historic underground nuclear explosions

Measurement of radioactive gas seepage from an underground nuclear explosion is one of the primary methods to confirm whether an event was nuclear in nature. Radioactive noble gas indicators that are commonly targeted by such measurements (e.g. ¹³³Xe, ³⁷Ar) have half-lives of 35 days or less. Argon-39, an activation product similar to ³⁷Ar, is produced by the interaction between neutrons and potassium in the surrounding geology and has a half-life of 269 years. Measurements taken at three sites near three historic underground nuclear test locations at the Nevada National Security Site have all shown highly elevated levels of ³⁹Ar in soil gas decades after the test events. Elevated levels of ³⁹Ar were also detected in atmospheric air collected near two of these sites, and outside the entrance of the one tunnel site. These measurements demonstrate that ³⁹Ar has the potential to be a long-term signature of an underground nuclear event which can be reliably detected at the surface or in the shallow subsurface. This radionuclide detection of an underground nuclear event decades after the event takes place is in contrast to the commonly held assumption that detecting underground nuclear events via radionuclides at the surface needs to be done in a matter of months. Depending upon what further studies show about the robustness of this signature in a variety of geological settings, it may in fact be easy to detect underground nuclear events at the surface for a very long time post-detonation.

Evidence review of physical distancing and partition screens to reduce healthcare acquired SARS-CoV-2

We review the evidence base for two newly introduced Infection prevention and control strategies within UK hospitals. The new standard infection control precaution of 2 metres physical distancing and the use of partition screens as a means of source control of infection for SARS-CoV-2. Following review of Ovid-MEDLINE and governmental SAGE outputs there is limited evidence to support the use of 2 metres physical distancing and partition screens within healthcare.

Distinct adaptation patterns between grip dynamics and arm kinematics when the body is upside-down

In humans, practically all movements are learnt and performed in a constant gravitational field. Yet, studies on arm movements and object manipulation in parabolic flight have highlighted very fast sensorimotor adaptations to altered gravity environments. Here, we wondered if the motor adjustments observed in those altered gravity environments could also be observed on Earth in a situation where the body is upside-down. To address this question, we asked participants to perform rhythmic arm movements in two different body postures (right-side-up and upside-down) while holding an object in precision grip. Analyses of grip-load force coordination and of movement kinematics revealed distinct adaptation patterns between grip and arm control. Grip force and load force were tightly synchronized from the first movements performed in upside-down posture, reflecting a malleable allocentric grip control. In contrast, velocity profiles showed a more progressive adaptation to the upside-down posture and reflected an egocentric planning of arm kinematics. In addition to suggesting distinct mechanisms between grip dynamics and arm kinematics for adaptation to novel contexts, these results also suggest the existence of general mechanisms underlying gravity-dependent motor adaptation that can be used for fast sensorimotor coordination across different postures on Earth and, incidentally, across different gravitational conditions in parabolic flights, in human centrifuges, or in Space.NEW & NOTEWORTHY During rhythmic arm movements performed in an upside-down posture, grip control adapted very quickly, but kinematics adaptation was more progressive. Our results suggest that grip control and movement kinematics planning might operate in different reference frames. Moreover, by comparing our results with previous results from parabolic flight studies, we propose that a common mechanism underlies adaptation to unfamiliar body postures and adaptation to altered gravity.

First Measurement of Near-Threshold J/ψ Exclusive Photoproduction off the Proton

We report on the measurement of the γp→J/ψp cross section from E_{γ}=11.8  GeV down to the threshold at 8.2 GeV using a tagged photon beam with the GlueX experiment. We find that the total cross section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section dσ/dt has an exponential slope of 1.67±0.39  GeV^{-2} at 10.7 GeV average energy. The LHCb pentaquark candidates P_{c}^{+} can be produced in the s channel of this reaction. We see no evidence for them and set model-dependent upper limits on their branching fractions B(P_{c}^{+}→J/ψp) and cross sections σ(γp→P_{c}^{+})×B(P_{c}^{+}→J/ψp).

Validation of a national hand hygiene proxy measure in NHS Scotland

The Scottish national hand hygiene proxy measure uses the volume of alcohol-based hand rub (ABHR) purchased by NHS Scotland boards as an indicator of the number of hand hygiene moments being performed per patient-bed-day. The proxy measure calculation is based on the assumption that 3 mL of ABHR is used per hand hygiene moment. This study aimed to validate the volume of ABHR being used per hand hygiene moment. It found that the median volume of ABHR being used in practice is approximately 1 mL per hand hygiene moment, and that using this validated volume in the calculation substantially increases the proxy measure of hand hygiene compliance.

Preliminary Results of USA-European Field Trial on the Use of Patient-reported Measures in a Mobile Application and Potential Uses in Refugee Populations

Introduction

The use of patient-reported outcome measures in psychiatric practices in the United States is still in its beginning phases. More research is need to determine the usefulness of such measures and the optimal methods to present them to patients and practitioners in routine care settings.

Objectives

This presentation will describe the research plan for testing a group of patient-reported outcome measures using digital applications. Potential opportunities for use in underserved refugee populations will be presented.

Methods

The outcome measures were selected from those recommended in DSM-5 Section III, including cross-cutting symptom and disability measures. A user-friendly digital application was developed for data collection, synthesis, and presentation. The research plan has three phases: focus groups with patients and clinicians, piloting of methods, and the main study, a pragmatic trial comparing treatment outcomes using outcome measurement versus usual care.

Results

Results of the focus group sessions will be presented, along with changes made to the measures and the digital application in response to these results. Current status of the research project will be discussed.

Conclusions

The results of this research project will bring greater clarity to questions on the role of outcome measurements in improving quality of care and patient outcomes. With ever greater use of smart phones, tablets, and personal computers, digital technology has the potential to facilitate psychiatric assessment and treatment for underserved, difficult-to-reach populations such as refugees.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Physiological mechanisms for stabilizing the limb when acting against physical constraints

Smooth physical interaction with our environment, such as when working with tools, requires adaptability to unpredictable perturbations that can be achieved through impedance control of multi-joint limbs. Modulation of arm stiffness can be achieved either increasing co-contraction of antagonistic muscles or by increasing the gain of spinal reflex loops. According to the "automatic gain scaling" principle, the spinal reflex gain, as measured via the H-reflex, scales with muscle activation. A previous experiment from our labs suggested, however, that reflex gains might instead be scaled to the force exerted by the limb, perhaps as a means to counteract destabilizing external forces. The goal of our experiment was to test whether force output, rather than the muscular activity per se, could be the critical factor determining reflex gain. Five subjects generated different levels of force at the wrist with or without assistance to dissociate applied force from agonist muscular activity. We recorded contact force, EMG and H-reflex response from a wrist flexor. We did not find a strict relationship between reflex gain and contact force but nor did we observe consistent modulation of reflex gain simply as a function of agonist muscle activity. These results are discussed in relation to the stability of the task constraints.

"Cerebellar contribution to visuo-attentional alpha rhythm: insights from weightlessness"

Human brain adaptation in weightlessness follows the necessity to reshape the dynamic integration of the neural information acquired in the new environment. This basic aspect was here studied by the electroencephalogram (EEG) dynamics where oscillatory modulations were measured during a visuo-attentional state preceding a visuo-motor docking task. Astronauts in microgravity conducted the experiment in free-floating aboard the International Space Station, before the space flight and afterwards. We observed stronger power decrease (~ERD: event related desynchronization) of the ~10 Hz oscillation from the occipital-parietal (alpha ERD) to the central areas (mu ERD). Inverse source modelling of the stronger alpha ERD revealed a shift from the posterior cingulate cortex (BA31, from the default mode network) on Earth to the precentral cortex (BA4, primary motor cortex) in weightlessness. We also observed significant contribution of the vestibular network (BA40, BA32, and BA39) and cerebellum (lobule V, VI). We suggest that due to the high demands for the continuous readjustment of an appropriate body posture in free-floating, this visuo-attentional state required more contribution from the motor cortex. The cerebellum and the vestibular network involvement in weightlessness might support the correction signals processing necessary for postural stabilization, and the increased demand to integrate incongruent vestibular information.

The effect of augmenting early nutritional energy delivery on quality of life and employment status one year after ICU admission

Augmenting energy delivery during the acute phase of critical illness may reduce mortality and improve functional outcomes. The objective of this sub-study was to evaluate the effect of early augmented enteral nutrition (EN) during critical illness, on outcomes one year later. We performed prospective longitudinal evaluation of study participants, initially enrolled in The Augmented versus Routine approach to Giving Energy Trial (TARGET), a feasibility study that randomised critically ill patients to 1.5 kcal/ml (augmented) or 1.0 kcal/ml (routine) EN administered at the same rate for up to ten days, who were alive at one year. One year after randomisation Short Form-36 version 2 (SF-36v2) and EuroQol-5D-5L quality of life surveys, and employment status were assessed via telephone survey. At one year there were 71 survivors (1.5 kcal/ml 38 versus 1.0 kcal/ml 33; P=0.55). Thirty-nine (55%) patients consented to this follow-up study and completed the surveys (n = 23 and 16, respectively). The SF-36v2 physical and mental component summary scores were below normal population means but were similar in 1.5 kcal/ml and 1.0 kcal/ml groups (P=0.90 and P=0.71). EuroQol-5D-5L data were also comparable between groups (P=0.70). However, at one-year follow-up, more patients who received 1.5 kcal/ml were employed (7 versus 2; P=0.022). The delivery of 1.5 kcal/ml for a maximum of ten days did not affect self-rated quality of life one year later.

Inertial torque during reaching directly impacts grip-force adaptation to weightless objects

A hallmark of movement control expressed by healthy humans is the ability to gradually improve motor performance through learning. In the context of object manipulation, previous work has shown that the presence of a torque load has a direct impact on grip-force control, characterized by a significantly slower grip-force adjustment across lifting movements. The origin of this slower adaptation rate remains unclear. On the one hand, information about tangential constraints during stationary holding may be difficult to extract in the presence of a torque. On the other hand, inertial torque experienced during movement may also potentially disrupt the grip-force adjustments, as the dynamical constraints clearly differ from the situation when no torque load is present. To address the influence of inertial torque loads, we instructed healthy adults to perform visually guided reaching movements in weightlessness while holding an unbalanced object relative to the grip axis. Weightlessness offered the possibility to remove gravitational constraints and isolate the effect of movement-related feedback on grip force adjustments. Grip-force adaptation rates were compared with a control group who manipulated a balanced object without any torque load and also in weightlessness. Our results clearly show that grip-force adaptation in the presence of a torque load is significantly slower, which suggests that the presence of torque loads experienced during movement may alter our internal estimates of how much force is required to hold an unbalanced object stable. This observation may explain why grasping objects around the expected location of the center of mass is such an important component of planning and control of manipulation tasks.

Hair and bone as predictors of tissular mercury concentration in the western Alaska red fox, Vulpes vulpes

We evaluated if total mercury (THg) concentrations of keratin-based and bone-based tissues can predict THg concentrations in skeletal muscle, renal medulla, renal cortex, and liver. The THg concentration in matched tissues of 65 red foxes, Vulpes vulpes, from western Alaska was determined. Hair THg concentration had a significant positive correlation with liver, renal medulla, renal cortex, and muscle. The THg concentration for males and females is moderately predictive of THg concentration in the renal cortex and liver for these foxes based on R(2) values (R(2)=0.61 and 0.63, respectively). Bone is weakly predictive of THg concentration in muscle (R(2)=0.40), but not a reliable tissue to predict THg concentration in liver (R(2)=0.24), renal cortex (R(2)=0.35), or renal medulla (R(2)=0.25). These results confirm the potential use of trapped animals, specifically foxes, as useful Arctic sentinel species to inform researchers about patterns in THg levels over time as industrialization of the Arctic continues.

Timing of antenatal care and ART initiation in HIV-infected pregnant women before and after introduction of NIMART

In this review of routinely collected data from five community health centres in the Johannesburg Health District, we assess timing of antenatal care and antiretroviral therapy (ART) initiation in HIV-infected pregnant women before and after the introduction of nurse-initiated management of ART in antenatal clinics. There are important lessons to be learnt as we reflect on the South African prevention of mother-to-child transmission of HIV programme.

Gravity-dependent estimates of object mass underlie the generation of motor commands for horizontal limb movements

Moving requires handling gravitational and inertial constraints pulling on our body and on the objects that we manipulate. Although previous work emphasized that the brain uses internal models of each type of mechanical load, little is known about their interaction during motor planning and execution. In this report, we examine visually guided reaching movements in the horizontal plane performed by naive participants exposed to changes in gravity during parabolic flight. This approach allowed us to isolate the effect of gravity because the environmental dynamics along the horizontal axis remained unchanged. We show that gravity has a direct effect on movement kinematics, with faster movements observed after transitions from normal gravity to hypergravity (1.8g), followed by significant movement slowing after the transition from hypergravity to zero gravity. We recorded finger forces applied on an object held in precision grip and found that the coupling between grip force and inertial loads displayed a similar effect, with an increase in grip force modulation gain under hypergravity followed by a reduction of modulation gain after entering the zero-gravity environment. We present a computational model to illustrate that these effects are compatible with the hypothesis that participants partially attribute changes in weight to changes in mass and scale incorrectly their motor commands with changes in gravity. These results highlight a rather direct internal mapping between the force generated during stationary holding against gravity and the estimation of inertial loads that limb and hand motor commands must overcome.

‘Feedback: Where data finally get thrilling’ – tools for facility managers to use data for improved health outcomes in the prevention of mother-to-child transmission of HIV and antiretroviral therapy

Data use and data quality continue to be a challenge for government sector health facilities and districts across South Africa. Led by the National Department of Health, key stakeholders, such as the Anova Health Institute and district health management teams, are aligning efforts to address these gaps. Coverage and correct implementation of existing tools – including TIER.net, routine data collection forms and the South African District Health Information System – must be ensured. This conference report provides an overview of such tools and summarises suggestions for quality improvement, data use and systematic evaluation of data-related interventions.

Keep your head on straight: facilitating sensori-motor transformations for eye-hand coordination

In many day-to-day situations humans manifest a marked tendency to hold the head vertical while performing sensori-motor actions. For instance, when performing coordinated whole-body motor tasks, such as skiing, gymnastics or simply walking, and even when driving a car, human subjects will strive to keep the head aligned with the gravito-inertial vector. Until now, this phenomenon has been thought of as a means to limit variations of sensory signals emanating from the eyes and inner ears. Recent theories suggest that for the task of aligning the hand to a target, the CNS compares target and hand concurrently in both visual and kinesthetic domains, rather than combining sensory data into a single, multimodal reference frame. This implies that when sensory information is lacking in one modality, it must be 'reconstructed' based on information from the other. Here we asked subjects to reach to a visual target with the unseen hand. In this situation, the CNS might reconstruct the orientation of the target in kinesthetic space or reconstruct the orientation of the hand in visual space, or both. By having subjects tilt the head during target acquisition or during movement execution, we show a greater propensity to perform the sensory reconstruction that can be achieved when the head is held upright. These results suggest that the reason humans tend to keep their head upright may also have to do with how the brain manipulates and stores spatial information between reference frames and between sensory modalities, rather than only being tied to the specific problem of stabilizing visual and vestibular inputs.

The provision of critical care in emergency departments at Canada

Introduction:

Critically ill patients are common in emergency medicine, and require expert care to maximize patient outcomes. However, little data is available on the provision of critical care in the ED. The goal of this study is to describe the management of critically ill patients in the ED via a survey of Canadian emergency physicians.

Materials and Methods:

A survey of attending physician members of CAEP was conducted by email. The survey was developed by the authors and internal validity was established prior to survey deployment. Data on physician demographics, hospital resources, use of invasive procedures, vasopressor/inotropic medications, length of stay in the ED and patient responsibility were assessed.

Results:

The survey response rate was 22.9%, with the majority of respondents possessing speciality training in EM (73.5%). Respondents indicated that critically ill patients were commonly managed in the ED, with 68.5% reporting >6 critically ill patients per month, and 12.4% indicating > 20 patients per month. Respondents indicated that the majority of critically ill patients remained in the ED for 1-4 hours (70%) after resuscitation, yet 18% remained in the ED for >5 hours. Patients with a “respiratory” etiology were the most common critically ill patient population reported, followed by “cardiovascular”, “infectious” and “traumatic illness”. Direct laryngoscopy was frequently performed (66.9%> 11 in the year prior to the survey) in the year prior to the survey, while other invasive procedures and vasopressor/inotropic medications were utilized less often. EM physicians were responsible for the management of critically ill patients in the ED, even after consultation to an inpatient service, and were often required to provided acute care to critically ill patients admitted to an ICU, yet remaining in the ED prior to transfer (20% reported > 50% of the time).

Conclusion:

Our survey demonstrates that critically ill patients are common in Canadian ED's, and that EMP's are often responsible to provide care for prolonged period of time. In addition, the use of invasive procedures other then direct laryngoscopy was variable. Further research is warranted to determine the impact of delayed transfer and ED physician management of critically ill patients in the ED.

Tuberculosis in HIV programmes in lower-income countries: practices and risk factors

BACKGROUND

Tuberculosis (TB) is a common diagnosis in human immunodeficiency virus (HIV) infected patients on antiretroviral treatment (ART).

OBJECTIVE

To describe TB-related practices in ART programmes in lower-income countries and identify risk factors for TB in the first year of ART.

METHODS

Programme characteristics were assessed using standardised electronic questionnaire. Patient data from 2003 to 2008 were analysed and incidence rate ratios (IRRs) calculated using Poisson regression models.

RESULTS

Fifteen ART programmes in 12 countries in Africa, South America and Asia were included. Chest X-ray, sputum microscopy and culture were available free of charge in respectively 13 (86.7%), 14 (93.3%) and eight (53.3%) programmes. Eight sites (53.3%) used directly observed treatment and five (33.3%) routinely administered isoniazid preventive treatment (IPT). A total of 19 413 patients aged ≥ 16 years contributed 13,227 person-years of follow-up; 1081 new TB events were diagnosed. Risk factors included CD4 cell count (>350 cells/μl vs. <25 cells/μl, adjusted IRR 0.46, 95%CI 0.33-0.64, P < 0.0001), sex (women vs. men, adjusted IRR 0.77, 95%CI 0.68-0.88, P = 0.0001) and use of IPT (IRR 0.24, 95%CI 0.19-0.31, P < 0.0001).

CONCLUSIONS

Diagnostic capacity and practices vary widely across ART programmes. IPT prevented TB, but was used in few programmes. More efforts are needed to reduce the burden of TB in HIV co-infected patients in lower income countries.

Probability of freezing in the freeze-avoiding beetle larvae Cucujus clavipes puniceus (Coleoptera: Cucujidae) from interior Alaska

Freeze-avoiding insects must resist freezing or die. A suite of adaptations to low temperatures, including the production of antifreeze proteins, colligative antifreezes (polyols), and dehydration allows most individuals to prevent freezing below the lowest ambient temperatures experienced in situ; however, there can be a wide variance in the minimum temperatures that individuals of freeze-avoiding species reach before freezing. We used logistic regression to explore factors that affect this variance and to estimate the probability of freezing in larvae of the freeze-avoiding beetle Cucujus clavipes puniceus. We hypothesized that water content ≤0.5 mg mg(-1) dry mass would lead to deep supercooling (avoidance of freezing below -58°C). We found a significant interaction between water content and ambient below-snow temperature and a significant difference between individuals collected from two locations in Alaska: Wiseman and Fairbanks. Individuals collected in Wiseman deep supercooled with greater water content and to a greater range of ambient temperatures than individuals collected in Fairbanks, leading to significantly different lethal water contents associated with 50% probability of freezing.

Prioritising prevention strategies for patients in antiretroviral treatment programmes in resource-limited settings

Expanded access to antiretroviral therapy (ART) offers opportunities to strengthen HIV prevention in resource-limited settings. We invited 27 ART programmes from urban settings in Africa, Asia and South America to participate in a survey, with the aim to examine what preventive services had been integrated in ART programmes. Twenty-two programmes participated; eight (36%) from South Africa, two from Brazil, two from Zambia and one each from Argentina, India, Thailand, Botswana, Ivory Coast, Malawi, Morocco, Uganda and Zimbabwe and one occupational programme of a brewery company included five countries (Nigeria, Republic of Congo, Democratic Republic of Congo, Rwanda and Burundi). Twenty-one sites (96%) provided health education and social support, and 18 (82%) provided HIV testing and counselling. All sites encouraged disclosure of HIV infection to spouses and partners, but only 11 (50%) had a protocol for partner notification. Twenty-one sites (96%) supplied male condoms, seven (32%) female condoms and 20 (91%) provided prophylactic ART for the prevention of mother-to child transmission. Seven sites (33%) regularly screened for sexually transmitted infections (STI). Twelve sites (55%) were involved in activities aimed at women or adolescents, and 10 sites (46%) in activities aimed at serodiscordant couples. Stigma and discrimination, gender roles and funding constraints were perceived as the main obstacles to effective prevention in ART programmes. We conclude that preventive services in ART programmes in lower income countries focus on health education and the provision of social support and male condoms. Strategies that might be equally or more important in this setting, including partner notification, prompt diagnosis and treatment of STI and reduction of stigma in the community, have not been implemented widely.

Movement Stability Under Uncertain Internal Models of Dynamics

Sensory noise and feedback delay are potential sources of instability and variability for the on-line control of movement. It is commonly assumed that predictions based on internal models allow the CNS to anticipate the consequences of motor actions and protect the movements from uncertainty and instability. However, during motor learning and exposure to unknown dynamics, these predictions can be inaccurate. Therefore a distinct strategy is necessary to preserve movement stability. This study tests the hypothesis that in such situations, subjects adapt the speed and accuracy constraints on the movement, yielding a control policy that is less prone to undesirable variability in the outcome. This hypothesis was tested by asking subjects to hold a manipulandum in precision grip and to perform single-joint, discrete arm rotations during short-term exposure to weightlessness (0 g), where the internal models of the limb dynamics must be updated. Measurements of grip force adjustments indicated that the internal predictions were altered during early exposure to the 0 g condition. Indeed, the grip force/load force coupling reflected that the grip force was less finely tuned to the load-force variations at the beginning of the exposure to the novel gravitational condition. During this learning period, movements were slower with asymmetric velocity profiles and target undershooting. This effect was compared with theoretical results obtained in the context of optimal feedback control, where changing the movement objective can be directly tested by adjusting the cost parameters. The effect on the simulated movements quantitatively supported the hypothesis of a change in cost function during early exposure to a novel environment. The modified optimization criterion reduces the trial-to-trial variability in spite of the fact that noise affects the internal prediction. These observations support the idea that the CNS adjusts the movement objective to stabilize the movement when internal models are uncertain.

Clinical trials: the viewpoint of children with a chronic illness compared with healthy children

The views of over 200 children (11-16 years old, who were either healthy or attending paediatric medical clinics with a chronic illness) on issues relating to paediatric clinical trials were determined by a questionnaire. Children with a chronic illness had a better understanding of the concept of dosing of medicines (40% vs 23%) and placebo (34% vs 20%). They were more likely to support children's involvement in clinical trials (51% vs 37%). The altruistic nature of children in both groups was similar. It was of concern, however, that 57-63% children would participate as healthy volunteers in a cancer drug trial. Both groups were able to differentiate between the different types of illnesses where it is appropriate to study medicines in children (86-89% for illness where there is no treatment; 34-40% for 'me-too' drugs). Young people should be given more opportunities to be involved in decision-making regarding clinical trials of medicines.

Neck dissection: past and present

The presence of lymph node metastasis to the neck is accepted as one of the single most important adverse prognostic indicators of survival in squamous cell carcinoma of the head and neck. Neck dissection in its various forms is the standard surgical treatment for clinical and subclinical metastatic cancer to the neck. This paper is a review of the anatomy of the neck, history and specific types of neck dissection, indications, therapeutic options, and current challenges in the treatment of metastatic neck disease.

"They see you as a different thing": the experiences of men who have sex with men with healthcare workers in South African township communities

OBJECTIVES

To describe interactions between men who have sex with men (MSM) and healthcare workers (HCW) in peri-urban township communities in South Africa.

METHOD

Qualitative study using semistructured in-depth interviews and focus group discussions in the Gauteng province townships of Soweto and Mamelodi. 32 MSM were purposively sampled for in-depth interviews and 15 for focus group discussions. Topics explored included identity, sexuality, community life, use of health services and experiences of stigma and discrimination.

RESULTS

MSM felt their options for non-stigmatising sexual healthcare services were limited by homophobic verbal harassment by HCW. Gay-identified men sought out clinics with reputations for employing HCW who respected their privacy and their sexuality and challenged those HCW who mistreated them. Non-gay-identified MSM presented masculine, heterosexual identities when presenting for sexual health problems and avoided discussing their sexuality with HCW.

CONCLUSIONS

The strategies MSM employ to confront or avoid homophobia from HCW may not be conducive to sexual health promotion in this population. Interventions that increase the capacity of public sector HCW to provide appropriate sexual health services to MSM are urgently needed.

Population pharmacokinetics of tenofovir in HIV-1-infected pregnant women and their neonates (ANRS 12109)

Thirty-eight human immunodeficiency virus-1 (HIV-1)-infected pregnant women were administered tenofovir disoproxil fumarate (TDF; 300 mg)-emtricitabine (FTC; 200 mg) tablets: two at labor initiation and one daily for 7 days postpartum. Maternal, umbilical, and neonatal plasma tenofovir concentrations were measured by high-performance liquid chromatography and analyzed using a population approach. Data were described using a two-compartment model for the mother, an effect compartment linked to maternal circulation for cord, and a neonatal compartment disconnected after delivery. Absorption was greater for women delivering by caesarian section than for those delivering vaginally. The maternal 600 mg TDF administration before delivery produces the same concentrations as 300 mg administration in other adults. If the time elapsed between maternal administration and delivery is >or=12 h, two tablets of TDF-FTC should be readministered. Tenofovir showed good placental transfer (60%). Administering 13 mg/kg of TDF as soon as possible after birth should produce neonatal concentrations comparable with those observed in adults.

The relationship between HAART use and sexual activity among HIV-positive women of reproductive age in Brazil, South Africa, and Uganda

The purpose of this study was to determine whether current HAART use is associated with recent sexual intercourse among HIV-infected women (18-49 years) from Brazil, South Africa and Uganda. We conducted an analysis of survey data from a cross-sectional study, which enrolled 179 HIV-infected women receiving regular care from the Mbarara Hospital HIV Clinic in Uganda (n=85); the Perinatal HIV Research Unit in Soweto, South Africa (n=50); and the IPEC-Fiocruz cohort in Rio de Janeiro, Brazil (n=44). The primary outcome was sexual intercourse in the previous month. Secondary outcomes were protected sex and contraceptive use. We found that overall, 46% reported recent sexual intercourse. After adjusting for covariates, recent sexual intercourse was not associated with HAART use (AOR: 0.76; 95%CI: 0.34-1.72); however, it was significantly associated with being currently married, wanting to have more children and having higher HAART optimism. Among women reporting recent sexual intercourse (n=83), HAART users were significantly more likely to practice protected sex (crude OR: 3.64; 95%CI: 1.41-9.38) and non-significantly more likely to use contraceptive methods (crude OR: 2.15; 95%CI: 0.77-5.99). In summary, self-reported recent sexual intercourse is not more likely among women on HAART. Moreover, sexually active HAART users may be more likely to practice protected sex and use contraceptives.

Effect of remineralization/demineralization cycles on mineral profiles of Fuji IX Fast in vitro using electron probe microanalysis

BACKGROUND

There have been cononcerns about the dissolution of conventional glass ionomer cement (GIC) and its possible degradation when exposed to an acidic environment over time. The objective of this study was to investigate the effects of exposure of Fuji IX Fast to the simulated acidic aspects of the oral environment in terms of any change in the elemental composition of strontium (Sr), phosphorus (P), calcium (Ca) and fluorine (F) which resulted at the surface of this material.

METHODS

Sixty-five cylindrical block of Fuji IX Fast were prepared using split moulds. The demineralizing solution was an acetate buffered demineralizing solution at pH 403. The remineralizing solution was a buffered solution containing 1.5 mM Ca, 0.9 mM P and 10 ppm F at pH 7. The blocks of Fuji IX Fast were subjected either to two-day alternating cycles of remineralization and demineralization for up to 24 days (test); 6 two-day cycles of demineralizing or remineralizing solution separately, or deionized distilled water alone (controls) or were left untreated (base line control). Mineral profiles of Ca, P, Sr and F within 100 microm of the material surface were assessed following 8, 16 and 24 days of treatment (test); 4, 8 or 12 days (controls) or for baseline control samples, using electron probe microanalysis (EPMA).

RESULTS

There were significant changes in mineral profile in the test specimens in terms of Sr and Ca concentrations. A molecule for molecule exchange of these elements resulted between GIC and eluant solutions. Fluoride loss from the GIC occurredto the level comparable with uptake levels recorded in eluant solutions from previous studies. The ionic exchanges appeared to be the result of dissolution followed by an equilibrium-driven diffusion. These exchanges were superficial though substantial.

CONCLUSIONS

Simulated exposure of Fuji IX to the oral environment resulted in an exchange of Ca from the bathing solutions into Fuji IX to replace any Sr which was lost to the GIC. Fluorine loss from the GIC followed previously described patterns. The possible clinical significance of this exchange was discussed.

Clinical trials: the viewpoint of children

The views of 30 children (8-16 years old) attending paediatric medical clinics on paediatric clinical trials were determined by semi-structured interviews. Nineteen children recognised that there were risks involved with taking part in clinical trials. Risks concerned with being paid were recognised by all children.

Comparative uptake of fluoride ion into enamel from various topical fluorides in vitro

BACKGROUND

There are many forms of topical fluoride available today, making the decision as to which is most effective to manage the immediate caries risk problem at hand, very difficult. The objective of this project was to determine the concentration and pattern of fluoride ion uptake into enamel from a variety of categories of topical fluoride recently available in Australia.

METHODS

Extracted, intact molar teeth were sectioned to provide six plates of smooth surface enamel. Windows of enamel 2 x 6 mm were exposed to a variety of topical fluorides for periods simulating those used in vivo. Following drying, the slates of enamel were exposed to 2 ml of 0.1 M HCl as a chemical biopsy agent for incremental periods of time. The concentrations of fluoride ion in the biopsy solutions for both test and background (control) slates of enamel were determined directly using a fluoride combination selective electrode in conjunction with a high impedance pH meter. Cumulative amounts of fluoride were determined for each topical fluoride agent.

RESULTS

The concentrations of fluoride ion taken up into enamel were generally proportional to those present in each agent. However, those from APF gel greatly exceeded the amounts taken up from NaF gel. Also, the concentrations taken up from some of the highly concentrated metal fluorides were surprisingly low. Prior etching of enamel increased uptake and prolonged application of APF gel provided no extra benefit.

CONCLUSIONS

Some topical fluorides, e.g., APF gel, provided a greatly increased uptake and to a greater depth than other self-application products. However, the frequency of its use should be considered with caution where patients have glass-based restorations.

Enhancement of fluoride release from glass ionomer cement following a coating of silver fluoride

BACKGROUND

This study investigated the extent to which a coating of 10% silver fluoride (AgF) on discs of glass jonomer cements (GIGs) would enhance the release of fluoride ion into eluting solutions at varying pH.

MATERIALS AND METHODS

Forty discs each of Fuji LX, Fuji VII and of Vitrebond were prepared in a plastic mould. Twenty discs of each material were coated for 30 seconds with a 10% solution of AgF. Five discs each of coated and uncoated material were placed individually in 4m1 of differing eluant solutions. The eluant solutions comprised deionized distilled water (DDW) and three separate acetate buffered solutions at pH 7, pH 5 and pH 3. After 30 minutes the discs were removed and placed in five vials containing 4m1 of the various solutions for a further 30 minutes. This was repeated for further intervals of time up to 216 hours, and all eluant solutions were stored. Fluoride concentrations in the eluant solutions were estimated using a fluoride specific electrode, with TISAB IV as a metal ion complexing and ionic concentration adjustment agent. Cumulative fluoride release patterns were determined from the incremental data.

RESULTS

The coating of AgF greatly enhanced the level of fluoride ion release from all materials tested. Of the uncoated samples, Vitrehond released the greater concentrations of fluoride ion, followed by Fuji VII. However, cumulative levels of fluoride released from coated samples of the GICs almost matched those from coated Vitrebond.

CONCLUSIONS

It was concluded that a coating of 10% AgF on GICs and a resin modified GIC greatly enhanced the concentration of fluoride released from these materials. This finding might be applied to improving protection against recurrent caries, particularly in high caries risk patients, and in the atraumatic restorative technique (ART) of restoration placement.

The potential for dental plaque to protect against erosion using an in vivo-in vitro model--a pilot study

BACKGROUND

Tooth erosion is a problem for professional wine tasters (exogenous erosion from frequent exposure to wine acids) and for people with gastro oesophageal reflux disease (GORD) and bulimia who experience frequent reflux of gastric contents into the mouth (endogenous erosion from mainly HCl). The objective in this study was to determine whether plaque/pellicle could provide teeth with any protection from two common erosive acids, using an in vivo-in vitro technique.

METHODS

Tiles of human tooth enamel and root surfaces were prepared from six extracted, unerupted third molar teeth and sterilized. Mandibular stents were prepared for six volunteer subjects and the tiles bonded to the buccal flanges of these stents. They were worn initially for three days to permit a layer of pellicle and plaque to form over the tile surfaces, and for a further 10 days of experimentation. Following cleaning of the plaque/ pellicle layer from the tiles on the right side flange, all the tiles were submerged in either 0.06M HCl or white wine for an accumulated time of 600 and 1500 minutes, respectively. Depths of erosion were determined using light microscopy of sections of the enamel and root tiles. SEM of the lesion surfaces was carried out to investigate the nature of erosive damage and of plaque/pellicle remnants.

RESULTS

Retained plaque was found to significantly inhibit dental erosion on enamel, from contact with both HCl and wine, compared with that resulting following its removal. However, it was found to provide no significant protection on root surfaces. SEM analysis of the tile surfaces revealed marked etching of enamel on the cleaned surfaces, and considerable alteration to the appearance of remaining plaque and pellicle on most surfaces.

CONCLUSION

Within the limitations of numbers of specimens, dental plaque/pellicle provided a significant level of protection to tooth enamel against dental erosion from simulated gastric acids and from white wine, using an in vivo-in vitro model. It was unable to provide any significant protection to root surfaces from these erosive agents. Possible reasons for this difference are explored.

Effect of gravity on human spontaneous 10-Hz electroencephalographic oscillations during the arrest reaction

Electroencephalographic oscillations at 10 Hz (alpha and mu rhythms) are the most prominent rhythms observed in awake, relaxed (eye-closed) subjects. These oscillations may be considered as a marker of cortical inactivity or an index of the active inhibition of the sensory information. Different cortical sources may participate in the 10-Hz oscillation and appear to be modulated by the sensory context and functional demands. In microgravity, the marked reduction in multimodal graviceptive inputs to cortical networks participating in the representation of space could be expected to affect the 10-Hz activity. The effect of microgravity on this basic oscillation has heretofore not been studied quantitatively. Because the alpha rhythm has a functional role in the regulation of network properties of the visual areas, we hypothesised that the absence of gravity would affect its strength. Here, we report the results of an experiment conducted over the course of 3 space flights, in which we quantified the power of the 10-Hz activity in relation to the arrest reaction (i.e., in 2 distinct physiological states: eyes open and eyes closed). We observed that the power of the spontaneous 10-Hz oscillation recorded in the eyes-closed state in the parieto-occipital (alpha rhythm) and sensorimotor areas (mu rhythm) increased in the absence of gravity. The suppression coefficient during the arrest reaction and the related spectral perturbations produced by eye-opening/closure state transition also increased in on orbit. These results are discussed in terms of current theories on the source and the importance of the alpha rhythm for cognitive function.

Persistence of nevirapine-resistant HIV-1 in women after single-dose nevirapine therapy for prevention of maternal-to-fetal HIV-1 transmission

Single-dose nevirapine (sdNVP) for prevention of mother-to-child transmission of HIV-1 can select nevirapine (NVP)-resistant variants, but the frequency, duration, and clinical significance of this resistance is not well defined. We used a sensitive allele-specific PCR assay to assess the emergence and persistence of NVP-resistant variants in plasma samples from 22 women with HIV-1 subtype C infection who participated in a study of sdNVP for prevention of mother-to-child transmission of HIV-1. The women were categorized into three groups on the basis of detection of NVP resistance by standard genotype analysis. Group 1 (n = 6) had NVP resistance detected at 2 and 6 mo after sdNVP, but not at 12 mo. Group 2 (n = 9) had NVP resistance detected at 2 mo, but not 6 mo. Group 3 (n = 7) had no NVP resistance detected at any time point. Allele-specific PCR analysis for the two most common NVP resistance mutations (K103N and Y181C) detected NVP-resistant variants in most (16 of 21) samples that were negative for NVP resistance by standard genotype, at levels ranging from 0.1% to 20% 1 yr after treatment. The frequency of NVP-resistant mutations decreased over time, but persisted above predose levels for more than 1 yr in > or = 23% of the women. These findings highlight the urgent need for studies assessing the impact of sdNVP on the efficacy of subsequent antiretroviral therapy containing NVP or other nonnucleoside reverse transcriptase inhibitors.

Kinematic and dynamic processes for the control of pointing movements in humans revealed by short-term exposure to microgravity

The generation of accurate motor commands requires implicit knowledge of both limb and environmental dynamics. The action of gravity on moving limb segments must be taken into account within the motor command, and may affect the limb trajectory chosen to accomplish a given motor task. Exactly how the CNS deals with these gravitoinertial forces remains an open question. Does the CNS measure gravitational forces directly, or are they accommodated in the motor plan by way of internal models of physical laws? In this study five male subjects participated. We measured kinematic and dynamic parameters of upward and downward arm movements executed at two different speeds, in both normal Earth gravity and in the weightless conditions of parabolic flight. Exposure to microgravity affected velocity profiles for both directions and speeds. The shape of velocity profiles (the ratio of maximum to mean velocity) and movement duration both showed transient perturbations initially in microgravity, but returned to normal gravity values with practice in 0 x g. Differences in relative time to peak velocity between upward versus downward movements, persisted for all trial performed in weightlessness. These differences in kinematic profiles and in the torque profiles used to produce them, diminished, however, with practice in 0 x g. These findings lead to the conclusion that the CNS explicitly represents gravitational and inertial forces in the internal models used to generate and execute arm movements. Furthermore, the results suggest that the CNS adapts motor plans to novel environments on different time scales; dynamics adapt first to reproduce standard kinematics, and then kinematics patterns are adapted to optimize dynamics.