Low Limb Research Articles

Cardiac strain among women workers in an industrial laundry.

Occupational heat exposure standards define permissible thermal conditions on the basis of metabolic heat production. However, even when energy expenditure is low, upright posture and repetitive upper limb motion may influence thermoregulatory behaviour through increased cardiovascular stress. The present study was undertaken to examine the relationship between work activity, thermal exposure and cardiac strain among women laundry workers engaged in sedentary, repetitive work activity. Ambient temperatures, work activity and heart rate were recorded during complete work shifts for 11 women over three days in summer and three days in winter. Workstation temperatures were significantly higher in summer. Analysis of continuous recordings of heart rate with respect to work activity showed (i) parallel increases in pulse rate and dominant arm movement frequency; (ii) different patterns of heart rate fluctuations for the two work cycles, with peaks during particular sub-tasks and when arms were in elevated positions. Recommended limits for cardiac strain indices were surpassed in both seasons, although in summer they were exceeded significantly more frequently. The part of cardiac effort attributable to thermoregulatory adjustments was also higher in summer while the fraction reflecting metabolic needs did not change with the season. These findings demonstrate high levels of cardiac strain in this work situation and raise the question of redefining heat exposure standards to include the prevention of excessive cardiac strain resulting from cumulative effects of heat load and ergonomic stressors.

Center-surround, orientation, and directional properties of turtle retinal horizontal cells.

The spatial transfer functions (STF) of L-type horizontal cells (HC) in turtle retina were measured using drifting sine wave grafting stimuli. Two classes of STF were identified: low-pass and band-pass. A low-pass STF corresponds to a linespread function (LSF) having an excitatory center that attenuates monotonically with distance; a band-pass STF corresponds to a LSF with an excitatory center and an inhibitory surround. Two models of the surround inhibitory mechanism, based on retinal outer plexiform layer (OPL) anatomy, are tested experimentally: surround mediated lateral inhibition and surround modulated self-inhibition. In both types, sign inverting pathways are based on GABA feedback synapses, and sign conserving pathways are based on excitatory synapses and gap junctions. Temperature variation was used to modify synaptic properties and study their effect on STF. The low frequency limb of band-pass STF was most sensitive to temperature changes; its slope increased with decreasing temperature. Synaptic properties were also manipulated pharmacologically. Cutoff frequency of low-pass STF decreased from 0.5 to 0.4 cpmm during exogenous GABA. Picrotoxin (PTX) increases upper cutoff frequency and decreases low frequency limb slope in band-pass STF. Band-pass STF of a ganglion cell (GC) has higher upper and lower cutoff frequencies than a HC in the same retinal region, which corresponds to strong spatial convergence from HC to GC. Orientation sensitivity and directional selectivity were found in some HC. Differences between major and minor response axes in orientation sensitive HC were small, ca. 2 dB; orientation differences in directionally selective HC were also small (ca. 1-2 dB) but directional asymmetry was large (ca. 10-12 dB).

Strain studies of cleavage development in the Chelmsford Formation, Sudbury Basin, Ontario

Cleavage formation in the Precambrian Chelmsford Formation of the Sudbury Basin, Ontario, is directly related to the finite strain and deformation path. Finite strain was measured at the outcrop scale from the shapes and orientations of deformed concretions within sandstones, at the microscopic scale from the relative positions of quartz grain centers, and via quantitative correlations between the anisotropy of magnetic susceptibility and strain. Two-dimensional strains measured in different sections at each site were combined into three-dimensional strain ellipsoids at 16 sites distributed throughout the Chelmsford Formation outcrop. Using the magnetic susceptibility correlation, a further 527 individual strain ellipsoids were obtained throughout the sites. A prominent strain gradient is mirrored by the progressive development of cleavage in the Chelmsford Formation, with strain and fabric development increasing in intensity from NW to SE. At the least deformed sites, cleavage is weak or absent. The finite strain reflects a combination of vertical compaction followed by coaxial, tectonic layer-parallel shortening acting in a subhorizontal, NW-SE direction. Pressure solution is the dominant deformation mechanism responsible for the formation of cleavage. Material removed by pressure solution is redeposited as pressure fringes on quartz grains, an observation which is compatible with the form of the deformation path which indicates little effect due to volume loss in cleavage formation in these sandstones. Folds within the Chelmsford Formation indicate formation by buckling but have very low limb dips. Decomposition of the finite strain tensor into a compactional part and a layer-parallel shortening part suggests that fold initiation and amplification was preceded by about 38% layer-parallel shortening. The large number of strain ellipsoids obtained from the Chelmsford Formation provide a significant data base from which a number of important tectonic problems can be examined including the predeformational shape of the Sudbury structure.

An assessment of OH airglow interference on the remote sensing of stratospheric HC1 via limb sounding in the near-I.R.

Abstract Chemiluminescent emission from the formation of vibrationally excited OH at an altitude of approximately 85 km presents a barrier to Earth limb measurements of near-infrared emissions originating in the stratosphere. High resolution measured spectra of OH airglow in the region of interest have not been reported, and thus it is difficult to assess its impact on moderately high resolution Earth limb spectroscopy capable of looking between strong OH lines. Low resolution rocket-borne spectrometer Earth limb measurements of OH airglow arc mathematically inverted to recover vibrational state populations that are used to simulate a higher resolution spectrum in the neighbourhood of 2843cm-1, Implications for remote sensing HCI are presented.

Diagnostic techniques in the investigation of shoulder lameness

Summary Methods of investigating horses with suspected shoulder lameness are described and discussed. The gait of shoulder lameness is characterised and compared with that of lower forelimb lameness. If lameness is slight, differentiation may be difficult, but if moderate, upper forelimb lameness usually results in shortening of the cranial phase of the stride and a low limb flight. Clinically, it may not be possible to differentiate between shoulder and elbow lameness without intra-articular anaesthesia. Practical aspects of intra-articular anaesthesia of the shoulder joint are reviewed. Synovial fluid must be retrieved to ensure that the needle is intra-articular. Up to 60 mins may elapse after injection of local anaesthetic before significant improvement occurs. Lameness is often improved rather than eliminated. A technique for standing radiography of the shoulder is described and the limitations of assessing a joint only by lateral projections are highlighted. There may be difficulties in positioning weanling foals and yearlings, resulting in superimposition of the shoulder joint, cervical and thoracic vertebra and ribs. It is concluded that a combination of a thorough clinical examination, faradism, local anaesthesia, synovial fluid analysis and radiography usually enables an accurate diagnosis to be reached.

Diagnostic techniques in the investigation of shoulder lameness.

Methods of investigating horses with suspected shoulder lameness are described and discussed. The gait of shoulder lameness is characterised and compared with that of lower forelimb lameness. If lameness is slight, differentiation may be difficult, but if moderate, upper forelimb lameness usually results in shortening of the cranial phase of the stride and a low limb flight. Clinically, it may not be possible to differentiate between shoulder and elbow lameness without intra-articular anaesthesia. Practical aspects of intra-articular anaesthesia of the shoulder joint are reviewed. Synovial fluid must be retrieved to ensure that the needle is intra-articular. Up to 60 mins may elapse after injection of local anaesthetic before significant improvement occurs. Lameness is often improved rather than eliminated. A technique for standing radiography of the shoulder is described and the limitations of assessing a joint only by lateral projections are highlighted. There may be difficulties in positioning weanling foals and yearlings, resulting in superimposition of the shoulder joint, cervical and thoracic vertebra and ribs. It is concluded that a combination of a thorough clinical examination, faradism, local anaesthesia, synovial fluid analysis and radiography usually enables an accurate diagnosis to be reached.

Peroneal Nerve Injury as a Complication of Acupuncture Needle

A Rare case of peroneal nerve injury is reported. A 37-year-old man had been treated with acupuncture for low back pain and right lower limb pain. One year after the treatment, the patient became aware of dysesthesis in the lateral aspect of the right lower leg. Radiological examination revealed a lot of acupuncture needles in lumbar and lower leg. After extraction of the needles, symptoms improved and clinical course was satisfactory.

A specific ECG triad associated with congestive heart failure.

No specific ECG sign of congestive heart failure has been described. This report deiineales a new triad consisting of 1) High precordial QRS voltage (SV1 or SV2 + RV5 or RV6 ≥ 3.5 mV); 2) Relatively low limb lead voltage (total QRS amplitude ≤ 0.8 m V in the limb leads); 3) Poor precordial R wave progression (R/S ratio < 3 in V4). In a retrospective study of 27 patients with idiopathic congestive cardiomyopathy, this triad was noted on at least one occasion in 19 cases (70%). This pattern was not noted at all in a control group of 100 adults without heart disease or in a separate control group of 30 preoperative patients with left venlricular hypertrophy due to aortic valve disease and normal left ventricular function. Three of these patients subsequently developed this pattern as a false positive sign immediately following aortic valve replacement. In a prospective survey of ECGs from 2000 consecutive patients, this triad appeared in 32 cases (1.6% prevalence). Definite evidence of current or previous left ventricular failure, usually severe, was noted in 29 of these cases (91% predictive valuel as evidenced by pulmonary venous hypertension or pulmonary edema on chest x‐ray, left ventricular ejection fraction ≤ 40%, or echocardiographic left ventricular end‐diastolic dimension ≥ 6.0 cm. The pathophysiology of this highly specific ECG triad probably relates to a number of mechanical and vectorial factors associated with congestive heart failure of a variety of etiologies. Left ventricular enlargement causes increased precordial voltage. In addition, the horizontal plane vector shifts posteriorly, orthogonal to the frontal plane, causing poor R wave progression and low limb lead voltage. Finally, increased extracellular fluid may preferentially attenuate QRS voltage in the more distal (limb) leads. (PAGE, Vol. 5, July‐August, 1982)

Membrane transport by guinea pig peritoneal exudate leukocytes: effect of phagocytosis on hexose and amino acid transport.

Short term, carrier mediated transport of D-glucose, L-leucine and L-lysine by guinea pig peritoneal macrophages was characterized. Analysis of the amino acid transport demonstrated two-limbed double reciprocal plots suggesting two transport systems for each amino acid. The low concentration limb of the curves established a Km of 0.1 mM for L-leucine and 0.05 mM for L-lysine; Vmax values were 2.0 and 2.85 nmole/mg protein/90 seconds, respectively. Leucine and lysine were shown to be competitive inhibitors of each other. Further competition studies revealed that other amino acids also had affinity for these carriers. Amino acid transport was found to be sensitive to sulfhydryl active compounds. Colchicine treatment of peritoneal macrophages did not inhibit the transport of the amino acids tested. Preloading macrophages with latex beads or heat-killed staphylococci by phagocytosis stimulated 2-deoxy-D-glucose (2-dOG) uptake markedly, but had no measurable effect on amino acid transport. Although total transport of 2-dOG increased in post-phagocytic macrophages, the kinetics of the system were not altered significantly. The Km for both pre- and post-phagocytic transport of 2-dOG was shown to be 1.2 mM and the Vmax was shown to increase from a pre-phagocytic value of 20 nmoles/mg protein/90 seconds to a post-phagocytic 27 nmoles/mg protein/90 seconds. Phagocytosis of heat-killed staphylococci by guinea pig polymorphonuclear leukocytes (PMNs), however, did not cause an augmentation in hexose transport in the cells. The presence of colchicine during phagocytosis did not alter subsequent uptake of amino acids by the macrophages.

A method to optimise the use of a grayshade scale in nuclear medicine images

We developed an algorithm which increases the effectiveness of any grayshade scaling system. This algorithm transforms the data in such a way that each level of gray is used to the same extent except the zero level (blank), which is used for a predetermined fraction of the picture elements. The detectors used are either a whole-body scanner or a scintillation camera, interfaced to a dedicated digital minicomputer (HP 5407A). The images obtained are framed in a 64 × 64 or 256 × 128 array of numbers. Programming is performed in Fortran II, under BCS (Basic Control System). In a first step the frequency distribution of countrates is determined, after which countrate limits are defined in this distribution in such a way that a first interval contains a preset number of the picture elements, while subsequent intervals are considered filled when they contain 1 29 of the residual elements. In a third step, correction factors are defined for each countrate, which make the limits of those intervals equidistant. Finally, those correction factors are applied to the original data array. This method has been applied with varying results to different scintigraphic images. Processing of bone scintigraphies in this way helps to overcome the problem of high bladder activity versus low limb activity. Liver scintigraphies are generally not modified. Myocardial images with 99mTc-pyrophosphate improve dramatically.

LITHIUM CARBONATE POISONING

A case of manic-depressive illness with sever lithium carbonate poisoning taking a long time to recovery, is reported.In this case, symptoms consisted of lethargy, fever, vomiting, tremor, lateral rotation of the head, upward gaze, conjugate lateral deviation of the eyes, anisocoria, nystagmus, muscle fasciculation, clonic contractions of large muscle groups, hyperactive tendon reflexes, Babinski sign positive, ataxia, and snout and grasp reflexes.Laboratory studies showed the following, leucocytosis and the elevated levels of serum GOT, GPT, LDH, BUN. Electroencephalograms showed generalized slowing. Cerebrospinal fluid examinations were normal.Within one month period, these acute toxic symptoms disappeared. EEG became normal after five months. The maximum serum level of lithium ion reached to 5.03 mEq / L. Twenty one days later, serum level of lithium ion was no longer presented. Six months later, a pneumoencephalogram showed slight dilatation of the lateral ventricles and widened cortical sulci in the frontal area.We also recognized mask-like facies, dysarthric, monotonous and low pitches speech, limb ataxia, dementia and change in personality. These clinical symptoms are gradually improving.In this case, in spite of lowere dosages as 400 mg/day lithium carbonate, it showed high serum lithium ion level as 5.08 mEq/L, when clinical toxic symptoms appeared.We thought, during the transition from mania to depression, the total body water was decreased, moreover the diet and liquid intake was reduced, in consequence serum lithium ion level increased and severe intoxication appeared.Prevention of intoxication required administration of proper dosage and maintaining laboratory and clinical control during treatment.

Layer shortening and fold-shape development in the buckling of single layers

The progressive development of folds by buckling in single isolated viscous layers compressed parallel to the layering and embedded in a less viscous host is examined in several ways; by use of experiments, an analogue model to simulate simultaneous buckling and flattening and by an application of finite-element analysis. The appearance of folds with a characteristic wavelength in an initially flat layer occurs in the experiments for viscosity ratios ( μ layer μ host = μ 1 μ 2 ) of between 11 and 100; progressive fold development after the initial folds have appeared is similar in the experiments and in the finite-element models. Except for the finite-element model for μ 1 μ 2 = 1,000 layer-parallel shortening occurs in the early stages of folding and a stage is reached where little further changes in arc length occur. The amount of layer-parallel shortening increases with decreasing viscosity contrast, and becomes relatively unimportant after the folds have attained limb dips of about 15°–25°. Thickness variations with dip are only significant here for the finite-element model with μ 1 μ 2 = 10 , and in experiments for μ 1 μ 2 = 5 where the layer is initially in the form of a moderate-amplitude sine wave. The variations range from a parallel to a near-similar fold geometry, and in general depend on the viscosity contrast, the degree of shortening and the initial wavelength/thickness ratio. They are very similar to the variations predicted by the analogue model of combined buckling and flattening. The difference between the thickness/dip variations in a fold produced by buckling at low viscosity contrast and one produced by flattening a parallel fold is marked at high limb dips and very slight at low limb dips. Many natural folds in isolated rock layers or veins show thickness/dip relationships expected for a flattened parallel fold, and some show relationships expected for buckling at low viscosity contrasts. Studies of the wavelength/thickness ratios in natural folds have suggested that competence contrast is often low. Many folds in isolated rock layers or veins whose geometry may vary between parallel and almost similar, and may be indistinguishable from those of flattened parallel folds, have probably developed by a process of buckling at low viscosity contrasts.