Smooth at one end and rough at the other: influence of object texture on grasping behaviour.

When picking up objects using a pinch grip, there are usually numerous places at which one could place the thumb and index finger. Yet, people seem to consistently place them at or close to the centre of mass (COM), presumably to minimize torque and therefore the required grip force. People also prefer to grasp objects by parallel surfaces and ones with higher friction coefficients (rough surfaces), to prevent the object from slipping when they lift it. Here, we examine the trade-off between friction and COM. Participants were asked to grasp and lift aluminium bars of which one end was polished and therefore smooth and the other was rough. Their finger positions were recorded to determine how they grasped the objects. The bars were oriented horizontally in the frontal plane, with the centre aligned with the participants' body midline. The bars varied in the horizontal offset between the COM and the edge of the rough region. The offset could be 0, 1 or 2 cm. We expected participants to grasp closer to the rough area than the centre of the bar. Completely rough bars and completely smooth bars served as control conditions. The slipperiness of the surface that was grasped affected the height of the grasping points, indicating that participants adjusted their grasping behaviour to the slipperiness of the surface. However, the tendency to grasp closer to the rough area was minimal. This shows that the judged COM largely determines how an object is grasped. Friction has very limited influence.

Central retinal vein occlusion as an uncommon complication of sarcoidosis.

A 23-year-old black women with acute blurred vision of the right eye was referred for ophthalmological examination. Fundus examination and fluorescence angiography showed a non-ischaemic central retinal vein occlusion (papillophlebitis). The diagnosis of sarcoidosis, suggested by the presence of bilateral hilar and mediastinal lymphadenopathy, was confirmed by transbronchial biopsy of the lymphadenopathy demonstrating noncaseating granulomas. The eye problems were successfully treated with systemic corticosteroids. Central retinal vein occlusion is a rare complication of sarcoidosis.

Visually Guided Haptic Search.

In this study, we investigate the influence of visual feedback on haptic exploration. A haptic search task was designed in which subjects had to haptically explore a virtual display using a force-feedback device and to determine whether a target was present among distractor items. Although the target was recognizable only haptically, visual feedback of finger position or possible target positions could be given. Our results show that subjects could use visual feedback on possible target positions even in the absence of feedback on finger position. When there was no feedback on possible target locations, subjects scanned the whole display systematically. When feedback on finger position was present, subjects could make well-directed movements back to areas of interest. This was not the case without feedback on finger position, indicating that showing finger position helps to form a spatial representation of the display. In addition, we show that response time models of visual serial search do not generally apply for haptic serial search. Consequently, in teleoperation systems, for instance, it is helpful to show the position of the probe even if visual information on the scene is poor.

Decidual vascularization and the expression of angiogenic growth factors and proteases in first trimester spontaneous abortions.

BACKGROUND: Decidual vascular development is important for implantation. This study analysed decidual vascular adaptation to implantation in correlation with miscarriage in decidual secretory endometrium (DSE), decidua parietalis (DP) and decidua basalis (DB) of miscarriage patients and matched controls. METHODS: Decidua was obtained during first trimester termination of pregnancy (controls) and vacuum aspiration in case of missed abortion (cases). Vascularization and the expression of VEGF-A, placental growth factor, Flt-1, KDR, angiopoietin (Ang)-1, Ang-2, TIE-2, and membrane-type matrix metalloproteinases MT1-, MT2-, MT3- and MT5-MMP were determined at mRNA and protein level. Uterine natural killer cells (CD56), macrophages (CD68), proliferation (Ki67) and apoptosis (activated caspase-3) were evaluated in consecutive sections. RESULTS: Decidual vascularization showed differences between cases and controls, i.e. fewer vessels with larger circumference in cases. This correlated with the differential expressions of various factors at mRNA/antigen level and with increased endothelial flt1, KDR, MT2- and MT5-MMP expression in miscarriage patients. The differences between cases and controls were probably not based on altered proliferation and/or apoptosis, since Ki67 and active Caspase-3 showed comparable expression levels in both groups. Although DB of cases and controls showed similar amounts of CD56- and CD68-positive cells, the case group did show elevated levels of CD56 in DSE (P < 0.05) and of CD68 in DP compared with the control group (P < 0.05). CONCLUSIONS: The differences in vascularization and in the expression of angiogenic factors and proteases between groups suggest a correlation between decidual vascularization and the occurrence of miscarriages.

Angiogenic growth factors and their receptors in first-trimester human decidua of pregnancies further complicated by preeclampsia or fetal growth restriction.

Disturbances in decidual and placental vascular development may play a role in the pathogenesis of pregnancy complications. This study focused on the role of angiogenic factors in the first trimester in the pathogenesis of preeclampsia (PE) and/or fetal growth restriction (FGR). First-trimester decidua was obtained during chorionic villous sampling.The expression of the angiogenic factors was determined by reverse transcriptase polymerase chain reaction and related to the pregnancy outcome. First-trimester decidua expressed all angiogenic factors.The differential expression of angiogenic factors appeared to be more prominent in FGR than in PE. These first-trimester samples provided a unique opportunity to obtain information regarding the onset of PE and FGR. First-trimester changes in angiogenic factor expression may well occur as a compensatory mechanism. This, in turn, may unintentionally set the stage for increased angiogenesis and altered decidual/placental vascular adaptation, which may be part of the pathogenesis of PE and/or FGR.

The natural course of Gaucher disease in The Netherlands: implications for monitoring of disease manifestations.

This retrospective study in 20 untreated type I Gaucher disease patients shows that in Dutch patients clinical manifestations of Gaucher disease type I are progressive in the majority of patients, children as well as adults. This is in contrast with studies among Jewish patients. Our results emphasize the need for a regular follow-up to enable timely initiation of enzyme therapy.

Phenylketonuria in The Netherlands: 93% of the mutations are detected by single-strand conformation analysis.

Single-strand conformational analysis was used to screen for genetic defects in all thirteen exons of the phenylalanine hydroxylase gene (PAH) in phenylketonuria and hyperphenylalaninemia patients in the Netherlands. Exons that showed a bandshift were sequenced directly. In this way, we were able to identify 93% of the PAH mutations in a panel of 34 patients. Twenty-one different mutations were found: 4 of these gene aberrations are novel.