The Gardos channel is responsible for CDNB-induced dense sickle cell formation

The red blood cells (RBCs) derived from blood taken from homozygous sickle cell (SS) patients demonstrate densities that are inversely proportional to the intracellular reduced glutathione (GSH) content. Addition of 1 mM 1-chloro-2,4-dinitrobenzene (CDNB) to low-density sickle cells (LDSS), at 4 degrees C, results in a shift of LDSS erythrocytes to high-density sickle cells (HDSS), with corresponding decreases in GSH. We have previously demonstrated that this CDNB effect was due to increased K(+) leakage and that dense cell formation could be inhibited by clotrimazole (specific for the Gardos channel) but not DIOA (specific for the K(+)-Cl(-) co-transport system) at pH 7.4 (Shartava et al. Am. J. Hematol. 1999;62:19-24). Here we demonstrate that clotrimazole (10 microM) inhibits dense cell formation at pH 7.1 and 6.8, while DIOA (1 mM) has no effect. As pH 6.8 is the optimal pH for the K(+)-Cl(-) co-transport system, we can now reasonably conclude that damage to the Gardos channel is responsible for CDNB-induced dense cell formation.

In vitro assessment of the structural integrity of the female condom after multiple wash, dry, and re-lubrication cycles

Since the introduction of the female condom in the early 90s, there have been numerous reports of reuse of the device. In response to these reports, studies were undertaken to evaluate the safety of female condom reuse. If reuse were shown to be safe, then programmatic costs of introduction of the female condom would be reduced allowing it to be more widely available. This article outlines the results of in vitro structural integrity testing of the female condom after multiple wash, dry, and re-lubrication cycles. Devices were tested up to 10 washes using water leakage, burst, and tensile seam testing. All results were compared to the United States Food and Drug Administration (US FDA) standards for an unused female condom. The results of the structural integrity tests for all 6 washing procedures examined in this study were above the FDA minimum standards for seam strength and burst tests. For the water leakage test, 3 of 6 washing procedures tested passed the required FDA minimum standards (no holes detected). From the results of the study, it seems that washing, drying, and re-lubricating the female condom up to 10 times leads to some deterioration in the structural integrity of the device for specified washing procedures. Further studies are currently being conducted to establish the safety of female condom reuse with respect to microbial retention, structural integrity after in vivo use, and viral permeability.

Spatial, not temporal cues drive predictive orienting movements during navigation: a virtual reality study

A fundamental property of the human brain is the ability to make predictions of future sensory and motor events. We have recently found that steering manoeuvres when walking along curvilinear trajectories are controlled by an anticipatory guidance of the direction of head (and eyes). However it is unclear whether a time-related or space-related signal triggers such anticipatory head orienting movements. By simulating navigation along a multi-legged virtual corridor we show that anticipatory orienting movements are triggered (in standing subjects) by reaching specific locations rather than by the time to the approaching corridor's bend. Similar to what happens in car driving, specific spatial features of the route rather than time to collision seem to drive steering.

Viewer-centered and body-centered frames of reference in direct visuomotor transformations

It has been hypothesized that the end-point position of reaching may be specified in an egocentric frame of reference. In most previous studies, however, reaching was toward a memorized target, rather than an actual target. Thus, the role played by sensorimotor transformation could not be disassociated from the role played by storage in short-term memory. In the present study the direct process of sensorimotor transformation was investigated in reaching toward continuously visible targets that need not be stored in memory. A virtual reality system was used to present visual targets in different three-dimensional (3D) locations in two different tasks, one with visual feedback of the hand and arm position (Seen Hand) and the other without such feedback (Unseen Hand). In the Seen Hand task, the axes of maximum variability and of maximum contraction converge toward the mid-point between the eyes. In the Unseen Hand task only the maximum contraction correlates with the sight-line and the axes of maximum variability are not viewer-centered but rotate anti-clockwise around the body and the effector arm during the move from the right to the left workspace. The bulk of findings from these and previous experiments support the hypothesis of a two-stage process, with a gradual transformation from viewer-centered to body-centered and arm-centered coordinates. Retinal, extra-retinal and arm-related signals appear to be progressively combined in superior and inferior parietal areas, giving rise to egocentric representations of the end-point position of reaching.

The practice and prevalence of dry sex among men and women in South Africa: a risk factor for sexually transmitted infections?

OBJECTIVES

To establish the prevalence of "dry sex" practice in a South African periurban population. To investigate the reasons for and factors influencing the practice of dry sex and to evaluate dry sex practice as a risk factor for sexually transmitted disease (STD).

DESIGN

Cross sectional sample survey.

METHODS

A random community sample of men and women aged between 16 and 35 in Gauteng Province, South Africa, were interviewed regarding the practice of dry sex using a structured interviewer administered questionnaire.

RESULTS

Dry sex practices were reported by 60% of men and 46% of women. Among younger individuals dry sex practice is far more common among the less educated, but there was no significant difference between education groups in the older respondents. A higher proportion of men practising dry sex than not practising dry sex reported having a past history of STD infection (56% versus 41%) although this difference was only marginally significant (p = 0.05). There was no difference in reported history of STD between women who practised dry sex and those who did not.

CONCLUSIONS

This study shows that dry sex practice is common in this community. The younger less educated group were the most likely to practise dry sex. Dry sex practice was associated with an increased prevalence of self reported STDs in men but not in women.

Respiratory depression in children receiving diazepam for acute seizures: a prospective study

The aim of this study was to determine the incidence of respiratory depression following the use of diazepam in children presenting with seizures. All children presenting with seizures to a children's A & E department over a period of 9 months were studied prospectively. Respiratory depression was defined as a fall in respiratory rate or oxygen saturation, or apnoea resulting in ventilation or resuscitation with bag-and-mask oxygen. There were 130 patient episodes involving 97 children who received treatment for their seizures before admission and/or in the A & E department. Administration of diazepam resulted in 122 patient episodes. The route of administration was rectal in 91 episodes, intravenous in 12 episodes, and both rectal and intravenous in 19 episodes. Eleven children had respiratory depression in relation to diazepam administration. Eight of these children required ventilation. The overall incidence of respiratory depression following the use of diazepam was 9%. The incidence of respiratory depression following diazepam given intravenously or rectally is high. The use of diazepam as first-line therapy for children with acute seizures needs to be reviewed.

Gravity affects the preferred vertical and horizontal in visual perception of orientation

The aim of this study was to evaluate the influence of gravity on the representation and storage of visual orientation information. On earth, measurements of response time and variability for a task of aligning remembered visual stimuli showed a distinct preference for horizontally and vertically oriented stimuli when the body and gravitational axes were aligned. This preference was markedly decreased or disappeared when the body axis was tilted with respect to gravity but was maintained for tests performed in microgravity. We conclude that subjects acquire and store visual orientation in a multi-modal reference frame that combines proprioceptive and gravitational information when both are available.

Unlicensed and off label drug use in neonates

AIM

To determine the extent of use of drugs that are either not licensed (unlicensed), or are outside the terms of their product licence (off label) in a neonatal intensive care unit.

METHODS

A prospective study was conducted over 13 weeks.

RESULTS

455 prescription episodes were administered to 70 babies. 63 (90%) patients were given a drug that was either unlicensed or used in an off label way. 54.7% prescription episodes were off label, many for more than one reason, and 9.9% (45) were unlicensed; 35.4% (161) prescription episodes were licensed.

CONCLUSION

The use of unlicensed and off label drugs in neonatal intensive care seems to be far greater than other paediatric settings. This highlights the difficulties faced by those trying to ensure safe and effective prescribing for neonates. Urgent action is required to resolve this situation.

Child extrafamilial sexual abuse: predicting parent and child functioning

OBJECTIVE

This study evaluated the emotional and behavioral adjustment of parents and children within 3 months and 1 year after the discovery of child extrafamilial sexual abuse.

METHOD

Ninety-two case parents (63 mothers, 29 fathers) and 56 children were compared to a nonclinical comparison group of 136 parents (74 mothers, 62 fathers) and 75 children. Parent adjustment was assessed using self-report measures while child functioning was assessed using a combination of child-, parent- and teacher-report measures.

RESULTS

Mothers, fathers and sexually abused children experienced clinically significant effects both initially and at 12 months post-disclosure. Children's perceptions of self-blame and guilt for the abuse and the extent of traumatization predicted their self-reported symtomatology at 3 months and 1 year post-disclosure. Child age and gender also significantly contributed to the prediction of many of the child outcome measures. No abuse-related variable was related to any child self-report measure. Mothers' satisfaction in the parenting role, perceived support and intrusive symptoms predicted their initial emotional functioning. Avoidant symptoms, child's internalizing behavior and mothers' initial emotional functioning were significant predictors of longer-term emotional functioning.

CONCLUSIONS

Results emphasize the need to address children's abuse-related attributions and underscore the need to expand our focus beyond the child victims to the traumatized families.

Reference frames and internal models for visuo-manual coordination: what can we learn from microgravity experiments?

Gravity plays a role in many different levels of human motor behavior. It dictates the laws of motion of our body and limbs, as well as of the objects in the external world with which we wish to interact. The dynamic interaction of our body with the world is molded within gravity's constraints. The task of catching a ball that has been thrown toward a human subject typifies the kind of constraints that the nervous system must take into consideration during visuo-manual coordination on earth. By dissecting and examining the components of this task, one can see what kinds of problems must be solved by the central nervous system to generate coordinated motor actions in response to incoming sensory information. In this review, we use the example of a ball catching task to outline various issues in the field of human motor control and to ask the question as to how the microgravity environment of lower earth orbit can be used to probe the functioning of the human motor system.

Short-term memory for reaching to visual targets: psychophysical evidence for body-centered reference frames

Pointing to a remembered visual target involves the transformation of visual information into an appropriate motor output, with a passage through short-term memory storage. In an attempt to identify the reference frames used to represent the target position during the memory period, we measured errors in pointing to remembered three-dimensional (3D) targets. Subjects pointed after a fixed delay to remembered targets distributed within a 22 mm radius volume. Conditions varied in terms of lighting (dim light or total darkness), delay duration (0.5, 5.0, and 8.0 sec), effector hand (left or right), and workspace location. Pointing errors were quantified by 3D constant and variable errors and by a novel measure of local distortion in the mapping from target to endpoint positions. The orientation of variable errors differed significantly between light and dark conditions. Increasing the memory delay in darkness evoked a reorientation of variable errors, whereas in the light, the viewer-centered variability changed only in magnitude. Local distortion measurements revealed an anisotropic contraction of endpoint positions toward an "average" response along an axis that points between the eyes and the effector arm. This local contraction was present in both lighting conditions. The magnitude of the contraction remained constant for the two memory delays in the light but increased significantly for the longer delays in darkness. These data argue for the separate storage of distance and direction information within short-term memory, in a reference frame tied to the eyes and the effector arm.

Arm end-point trajectories under normal and micro-gravity environments

The purpose of the present experiment was to study the way in which the CNS represents gravitational force during vertical arm pointing movements. Movements in upward and downward directions were executed by two cosmonauts in normal-gravity and weightlessness. Analyses focused upon finger kinematics in the sagittal plane. In normal-gravity, downward direction movements showed smaller curvatures and greater relative times to peak velocity (AT/MT) when compared with upward direction movements. Data from the weightlessness experiments showed that whilst downward movements decreased their curvature during space flight, curvatures of upward movements changed slightly. Furthermore, AT/MT was modified during the first days in micro-gravity for both directions, recovering, however, to pre-flight values after 18 days in space. Results from the present study, provide evidence that gravitational force is centrally treated constituting an important component of the motor plan for vertical arm movements.

The Kinelite Project: a new powerful motion analyser for Spacelab and space station

The goal of the Kinelite Project is to develop a space qualified motion analysis system to be used in space by the scientific community, mainly to support neuroscience protocols. The measurement principle of the Kinelite is to determine, by triangulation mean, the 3D position of small, lightweight, reflective markers positioned at the different points of interest. The scene is illuminated by Infra Red flashes and the reflected light is acquired by up to 8 precalibrated and synchronized CCD cameras. The main characteristics of the system are: Camera field of view: 45 degrees; Number of cameras: 2 to 8; Acquisition frequency: 25, 50, 100, or 200 Hz; CCD format: 256 x 256; Number of markers: up to 64; 3D accuracy: 2mm; Main dimensions: 45 cm x 45 cm x 30 cm; Mass: 23 kg; Power consumption: less than 200 W. The Kinelite will first fly aboard the NASA Spacelab; it will be used, during the NEUROLAB mission (4/98), to support the "Frames of References and Internal Models" (Principal Investigator: Pr. A. Berthoz, Co Investigators: J. McIntyre, F. Lacquaniti).

Monitoring utilisation, quality & effectiveness of free antenatal care in an informal settlement in Gauteng

The aim of this study was to monitor utilisation, quality and effectiveness of free antenatal care from a review of clinic records. Starting randomly, 197 clinic records from four clinics were reviewed. Antenatal care was initiated at the end of the second trimester or in the third trimester, in an inadequate quantity (64% had made less than three visits). Teenagers were significantly more likely to attend only once than the older age groups (Chi-square = 12.5, df = 6, p = 0.05). Standard tasks such as age, weight, blood pressure, foetal heart monitoring, estimated gestational age and urine test results were recorded correctly. However, the effectiveness of care was difficult to assess due to incomplete records and the lack of blood test results. It was concluded that the provision of a free antenatal care service does not automatically increase utilisation; timing and quantity of care obtained were inadequate; and improvements in record keeping are essential for assessing the quality and effectiveness of care.

Hand trajectories of vertical arm movements in one-G and zero-G environments. Evidence for a central representation of gravitational force

The purpose of the present experiment was to study the way in which the central nervous system (CNS), represents gravitational force during vertical arm pointing movements. Movements in upward (against gravity) and downward (with gravity) directions, with two different mass loads (hand empty and with a hand-held 0.5-kg weight) were executed by eight subjects in a normal gravitational environment. Movements by two cosmonauts, in the two directions, were also tested in a state of weightlessness. Analyses focused upon finger trajectories in the sagittal plane. Subjects in a normal gravitational environment showed curved paths for both directions and weight conditions. In addition, downward movements showed significantly smaller curvatures than upward movements. Movement times were approximately the same for all the experimental conditions. Curvature differences between upward and downward movements persisted during space flight and immediately postflight. Movement times from both cosmonauts increased slightly during flight, but returned to normal immediately on reentry in a one-G environment. Results from the present study provide evidence that gravity is centrally represented in an anticipatory fashion as a driving force during vertical arm movement planning.

The efficacy of reducing agents or antioxidants in blocking the formation of dense cells and irreversibly sickled cells in vitro

We show that N-acetylcysteine (NAC) has the ability to cause statistically significant diminishment in the in vitro formation of irreversibly sickled cells (ISCs) at concentrations greater than 250 micromol/L. Other antioxidants, approved for human use (cysteamine, succimer, dimercaprol), were not efficacious. NAC had the ability to cause statistically significant conversion of ISCs formed in vivo back to the biconcave shape. NAC was also shown to reduce the formation of dense cells and increase the available thiols in beta-actin. We showed that diminishing reduced glutathione (GSH), by treatment with 1-chloro-2,4-dinitrobenzene, resulted in increased dense cells. We conclude the NAC blocks dense cell formation and ISC formation by targeting channels involved in cellular dehydration and beta-actin, respectively. The efficacy of NAC is probably due to its combined antioxidant activity and ability to increase intracellular GSH.

Ethical holistic thinking and practice for community health workers and nurses

If we take on board the assumption that social realities are perceived through filters of experience, social position, personality and emotion, then we accept that 'facts' can be differently construed or constructed Compassion cannot be taught as a competency, but we can be made aware through reflexive thinking that the closest we can ever get to a shared truth is through listening to and understanding the other. This paper is a modest attempt to provide some tools for community health workers and nurses who are concerned about the quality of their practice and wish to find creative solutions.

Hand trajectory formation during whole body reaching movements in man

End-effector trajectory formation was studied during a reaching movement using the whole body. The movements of various parts of the body were measured with the optoelectronic ELITE system. Wrist reaching movement paths showed noticeable curvatures. The analysis of various marker onset latencies revealed that the wrist was the last to move, always after the head, knee or trunk, suggesting a subordinate role of the focal component with respect to the primary role of the equilibrium component. These results suggest that reaching wrist movements are subjected to whole-body equilibrium constraints in addition to constraints placed upon end-effector kinematics or the dynamic optimization of upper-limb movements.

Technical evolutions of the French multipurpose instruments for Cognitive Neurosciences

Since the first French flight in space in 1982, the CNES has developed a wide range of instruments, especially in the field of Neurosciences. The design of these instruments has considerably evolved from rather simple equipment up to much more sophisticated tools that are being specially tailored for these missions. Four major phases can be identified: -a simple adaptation of an echographe leading to the first neurosciences experiments (the ARAGATZ'88 mission), -the ILLUSIONS and VIMINAL instruments used during the ANTARES'92 and ALTAIR'93 missions, -the COGNILAB instrument developed for the CASSIOPEE'96 mission, to be re-used in 1997 and in 1999, -a preliminary design of the 1999 mission payload, including virtual reality concepts, in a modular design to adapt to the European COF. Aside from the evolution of scientific requirements, the experience gained during the flights led to progressive improvements in the different technical parts, including visual system, body restraint systems, accessories, such as a force feedback joystick, computer and software, etc. This paper describes the technical evolutions in the CNES Neurosciences program.

Viewer-centered frame of reference for pointing to memorized targets in three-dimensional space

Pointing to a remembered visual target involves the transformation of binocular visual information into an appropriate motor output. Errors generated during pointing tasks may indicate the reference frames used by the CNS for the transformation and storage of the target position. Previous studies have proposed eye-, shoulder-, or hand-centered reference frames for various pointing tasks, depending on visual conditions. We asked subjects to perform pointing movements to remembered three-dimensional targets after a fixed memory delay. Pointing movements were executed under dim lighting conditions, allowing vision of the fingertip against a uniform black background. Subjects performed repeated movements to targets distributed uniformly within a small (radius 25 mm) workspace volume. In separate blocks of trials, subjects pointed to different workspace regions that varied in terms of distance and direction from the head and shoulder. Additional blocks were performed that differed in terms of starting position, effector hand, head rotation, and memory delay duration. Final pointing positions were quantified in terms of the constant and variable errors in three dimensions. The orientation of these errors was examined as a function of workspace location to identify the underlying reference frames. Subjects produced anisotropic patterns of variable error, with greater variability for endpoint distances from the body. The major axes of the variable-error tolerance ellipsoids pointed toward the eyes of the subject, independent of workspace region, effector hand (left or right), initial hand position, and head rotations. Constant errors were less consistent across subjects, but also tended to point toward the head and body. Both overshoots and undershoots of the target position were observed. Increasing the duration of the memory delay period increased the size but did not alter the orientation of the variable-error ellipsoids. Variability of the endpoint positions increased equally in all three Cartesian directions as the memory delay increased from 0.5 to 8.0 s. The anisotropy of variable errors indicates a viewer-centered reference frame for pointing to remembered visual targets with vision of the finger. The anisotropy of pointing variability stems from variability in egocentric binocular cues as opposed to reliance on allocentric visual references or to specific approximations in the sensorimotor transformation. Nevertheless, observed increases in variability with longer memory delays indicate that the short-term storage of the target position does not simply mirror the retinal and ocular sensory signals of the visually acquired target location. Thus spatial memory is carried out in an internal representation that is viewer-centered but that may be isotropic with respect to Cartesian space.