A unified method for calculating the center of pressure during wheelchair propulsion

The measurement of the center of pressure (COP) has been and continues to be a successful tool for gait analysis. The definition of a similar COP for wheelchair propulsion. however, is not straightforward. Previously, a COP definition similar to that used in force plate analysis had been proposed. Unfortunately, this solution has the disadvantage of requiring a separate COP definition for each plane of analysis. A definition of the generalized center of pressure (GCOP) which is consistent in all planes of analysis is derived here. This definition is based on the placement of a force-moment system, equivalent to the force-moment system at the hub, on a line in space where the moment vector (wrench moment) is parallel to the force vector. The parallel force-moment system is then intersected with three planes defined by anatomical landmarks on the hand. Data were collected using eight subjects at propulsion speeds of 1.34 m/s and 2.24 m/s (1.34 m/s only for subject 1, 0.894 m/s and 1.79 m/s for subject 8). Each subject propelled a wheelchair instrumented with a SMARTwheel. A PEAK 5 video system was used to determine the position of anatomical markers attached to each subject's upper extremity. The GCOP in the transverse plane of the wrist formed clusters for all subject's except subject 2 at 1.34 m/s. The clustering of the GCOP indicates that the line of action for the force applied by the hand is approximately perpendicular to the transverse plane through the wrist. When comparing the magnitude of the moment vector part of the wrench with the moment of the force vector of the wrench about the hub, the wrench moment is approximately an order of magnitude smaller. This indicates that the role of the wrist for wheelchair propulsion is primarily to stabilize the force applied by the arm and shoulder.     

Control of fibroblast populated collagen lattice contraction by antibody targeted photolysis of fibroblasts

BACKGROUND AND OBJECTIVE: Hypertrophic scarring and rigid scar contracture are disorders of wound healing for which there is presently no effective therapy. The dermal fibroblast plays a major role in scar fibrillogenesis and contracture. The objective of this study was to establish a selective and effective method to destroy fibroblasts. STUDY DESIGN/MATERIALS AND METHODS: An antifibroblast conjugate was synthesized by covalent attachment of the antifibroblast antibody PR2D3 to the photosensitizer Sn-chlorin e6. Fibroblasts were cultured in fibroblast-populated collagen lattices (FPCLs), incubated with the conjugate and exposed to light. The effect of the treatment on cell viability and the rate of contraction of the FPCL were assessed. RESULTS: The toxicity of antifibroblast conjugates increased with increasing conjugate concentration, light dose, and number of photosensitizers per antibody molecule, until nearly complete killing was achieved. The rate of lattice contraction after irradiation linearly correlated with the remaining viable fraction of fibroblasts. These conjugates were not cytotoxic to keratinocytes cultured on collagen lattices, and nonspecific conjugates could not cause significant fibroblast killing. Spatial selectivity was demonstrated using a light mask. CONCLUSIONS: Antibody-targeted photolysis is an effective and selective technique for controlling FPCL contraction in vitro and may have potential in vivo applications to modulate extracellular matrix remodeling by connective tissue cells.     

Aims, processes and problems of antenatal education as identified by three groups of childbirth teachers

OBJECTIVE: To establish whether variations exist in the philosophy and approach of three groups of childbirth teachers working in different organisations in the UK. PARTICIPANTS: Two midwifery Parentcraft Sisters working in the UK maternity services, three National Childbirth Trust Antenatal Teachers and two Active Birth Teachers working in the voluntary sector, and two Midwife Teachers. METHOD: Semi-structured interviews were tape-recorded, transcribed and analysed using a grounded theory approach to identify common categories. FINDINGS: All three groups of teachers identified similar aims for antenatal education, with the need to build clients' confidence in their ability to give birth and care for their babies as the most important. However, the process by which the various teachers attempted to realise their aims appeared to be very different. IMPLICATIONS FOR PRACTICE: In order to ensure the prioritization of antenatal education with purchasers and providers, childbirth teachers need to define more clearly the criteria by which it can be audited.     

First degree atrioventricular block caused by a calcified tumor of the atrioventricular septum

First degree atrioventricular block occurred in a 69-year-old patient with a calcified atrioventricular septum tumour. The patient suffered several episodes of syncope and the only abnormality found in the routine clinical work-up was a remarkable first degree atrioventricular block. The echocardiogram, computed tomography (CT) and the magnetic resonance imaging (MRI) procedure showed a calcified tumour in the posterior part of the left ventricle, between the left atrium and left ventricle, just beneath the aortic root spreading to the interventricular septum. It was suggested that the first degree atrioventricular block was caused by the tumour. The symptoms were relieved by implantation of permanent cardiac pacemaker.     

Divergent changes in survival for histological types of non-small-cell lung cancer in the southeastern area of The Netherlands since 1975

We studied the incidence and survival rates for the histological subtypes of non-small-cell lung cancer, using data from the Eindhoven Cancer Registry over the period 1975-94. The proportions with adenocarcinoma and large-cell undifferentiated carcinoma increased from 11% to 21% and from 11% to 15%, respectively, while those with squamous cell carcinoma decreased from 78% to 62%. The increase in the proportion with adenocarcinoma was only found among men. Although the overall prognosis for patients with non-small-cell lung cancer has remained unchanged, there have been divergent changes between morphological subtypes. Relative 1- and 5-year survival rates for squamous cell carcinoma have improved slightly from 48% to 51% and from 14% to 16%, respectively, because of an increase in the proportion with localized tumours, while relative 1- and 5-year survival rates for adenocarcinoma have decreased from 59% to 45% and from 28% to 18%, respectively, because of a decrease in localized tumours. The proportion with localized tumours and the relative 1-year survival for large-cell undifferentiated carcinoma (about 18% and 30% respectively) were markedly lower. The divergent trends could partly be explained by changes in the histological classification of tumours, but changes in patterns of risk and biological behaviour of adenocarcinoma cannot be excluded.     

Absorption, disposition kinetics, and metabolic pathways of cyclohexene oxide in the male Fischer 344 rat and female B6C3F1 mouse

Cyclohexene oxide (CHO) is a monomer intermediate used in the synthesis of pesticides, pharmaceuticals, and perfumes. Although CHO has a variety of industrial uses where direct human exposure is possible, very little is known about its fate in the body. Therefore, the objectives of this study were to determine the absorption, distribution, metabolism, and excretion of cyclohexene oxide after oral, intravenous, and dermal exposure in male Fischer 344 rats and female B6C3F, mice. After intravenous administration of [14C]CHO (50 mg/kg), CHO was rapidly distributed, metabolized, and excreted into the urine. Plasma concentrations of CHO rapidly declined and were below the limit of detection within 60 min. Average (+/- SD) values for terminal disposition half-life, apparent volume of distribution at steady-state, and systemic body clearance were: 19.3 +/- 1.6 min; 0.44 +/- 0.08 liter/kg; and 31.3 +/- 0.5 ml/kg * min, respectively. After oral administration of [14C]CHO (10 and 100 mg/kg), it was found that 14C-equivalents were rapidly excreted in the urine of both species. At 48 hr, the majority of the dose (73-93%) was recovered in urine, whereas fecal elimination accounted for only 2-5% of the dose. At no time after oral administration was parent CHO detected in the blood. However, its primary metabolite cyclohexane-1,2-diol was present for different lengths of time depending on the dose. Four metabolites were detected and identified in mouse urine by MS: cyclohexane-1,2-diol; cyclohexane-1,2-diol-O-glucuronide; N-acetyl-S-(2-hydroxycyclohexyl)-L-cysteine; and cyclohexane-1,2-diol-O-sulfate. The sulfate conjugate was not present in rat urine. Topical application of [14C]CHO (60 mg/kg) provided poor absorption in both species. The majority of 14C-equivalents applied dermally were recovered from the charcoal skin trap (approximately 90% of the dose). Only 4% of the dose was absorbed, and the major route of elimination was via the urine. To evaluate the toxicity of CHO, animals were given daily doses of CHO orally and topically for 28 days. No statistically significant changes in final body weights or relative organ weights were noted in rats or mice treated orally with CHO up to 100 mg/kg or up to 60 mg/kg when given topically. Very few lesions were found at necropsy, and none were considered compound related. In conclusion, regardless of route, CHO is rapidly eliminated and excreted into the urine. Furthermore, after either oral or dermal administration, it is unlikely that CHO reaches the systemic circulation intact due to its rapid metabolism, and is therefore unable to cause toxicity in the whole animal under the test conditions used in this study.     

Decrease of rotenone inhibition is a sensitive parameter of complex I damage in brain non-synaptic mitochondria of aged rats

We investigated NADH oxidation in non-synaptic and synaptic mitochondria from brain cortex of 4- and 24-month-old rats. The NADH oxidase activity was significantly lower in non-synaptic mitochondria from aged rats; we also found a significant decrease of sensitivity of NADH oxidation to the specific Complex I inhibitor, rotenone. Since the rotenone-binding site encompasses Complex I subunits encoded by mtDNA, these results are in accordance with the mitochondrial theory of aging, whereby somatic mtDNA mutations are at the basis of cellular senescence. Accordingly, a 5 kb deletion was detected only in the cortex of the aged animals.