Formaldehyde in pathology departments.

Toxic effects of formaldehyde in humans are discussed in relation to occupational exposure and tolerance to this agent. Carcinogenic and mutagenic properties of formaldehyde have been reported in animals and this has led to concern about a possible role in human cancer. The current state of affairs is reviewed in the light of a lack of direct evidence linking formaldehyde with cancer in man and in relation to recommended exposure levels. It is important to employ effective means of containment and practical methods for reducing exposure to formaldehyde in pathology departments and post-mortem rooms are described.

An electroblotting technique for assessing the integrity of the major immunogenic protein in foot-and-mouth disease virus vaccines.

A method has been developed whereby VP1, the major immunogenic protein of foot-and-mouth disease virus can be detected after electroblotting on nitrocellulose paper. Proteins can be examined in unfractionated virus harvests and after formulation as aluminium hydroxide-adjuvanted vaccines. The limit of detection is approximately 10 ng of VP1 and up to 20 samples can be analysed simultaneously. The technique allows the integrity of VP1 to be examined in fully formulated vaccines.

Botulinum toxin: a treatment for facial asymmetry caused by facial nerve paralysis.

Injury to the frontal or other facial nerve branches can result in an asymmetry that can be very distressful to both patient and surgeon. This is especially true following cosmetic procedures such as rhytidectomy. We propose a means to create temporary symmetry while awaiting the possible return of nerve function. Botulinum neurotoxin causes a muscle paralysis lasting for approximately 3 months, and it is well established as the preferred treatment for blepharospasm. A case is presented in which botulinum toxin type A was injected into the opposite functioning frontalis muscle of a patient with unilateral frontal nerve paralysis. The patient experienced satisfactory relief of the asymmetry caused by onesided forehead wrinkling and brow elevation. Botulinum toxin therapy should be considered for both temporary and permanent facial asymmetries due to facial nerve paralysis as well as spasm.

A method for determining the heat transfer and water vapour permeability of patient support systems.

The formation of pressure ulcers can be exacerbated by a breakdown in the integrity of the patient's skin caused by poor maintenance of the skin microclimate. Patient support systems (PSSs-specialised beds, mattresses, chairs, cushions and pads) play an important role in the dissipation of heat and moisture away from the skin/support interface which is necessary in order to maintain the physiological skin microclimate. This paper reports a laboratory method and theory for the simultaneous measurement of the heat and water vapour dissipating properties of PSSs. The results demonstrate that the method is extremely selective, exhibiting very significant differences between the PSSs tested. It also shows that assessing PSS covers independently does not necessarily indicate the overall performance of the complete PSS.

Five-year agreement for equipment acquisition.

A three-hospital system in western Canada had decided to replace its old imaging processing equipment but wrestled with the most effective way to purchase it. As Mr. Clark describes in this practical guide to the process, the hospitals combined their buying power, negotiated a long-term agreement and found a supplier committed to total quality management.

Thrust production and wake structure of a batoid-inspired oscillating fin.

Experiments are reported on the hydrodynamic performance of a flexible fin. The fin replicates some features of the pectoral fin of a batoid fish (such as a ray or skate) in that it is actuated in a travelling wave motion, with the amplitude of the motion increasing linearly along the span from root to tip. Thrust is found to increase with non-dimensional frequency, and an optimal oscillatory gait is identified. Power consumption measurements lead to the computation of propulsive efficiency, and an optimal efficiency condition is evaluated. Wake visualizations are presented, and a vortex model of the wake near zero net thrust is suggested. Strouhal number effects on the wake topology are also illustrated.

A particle detector for use in ventilation engineering.

An electronic particle counting device is described, based on a constant-temperature hot-wire anemometer probe. The device has found application in tracing the motions of droplets and measuring their concentration within ventilated areas when subjected to different types of ventilation. In this way the effectiveness of various systems may be determined.

Skin scales among airborne particles.

The air from a house and garden in a rural area has been sampled and the size distributions of the airborne particles have been determined. The particle concentrations are shown to be generally higher indoors. Changes in the particle concentration during various activities in a small room have been shown to be greatest for particles larger than 3 mum. diameter. Stereoscan microscopic observation has shown that many of the airborne particles in rooms and some from those in outside air appear to be scales of desquamated skin. The presence of protein in many of these particles complements the microscopic observations.

Neonatal skin temperature distribution using infra-red colour thermography.

1. Infra-red Colour Thermography was used to visualize skin temperatures over seven neonates nursed in a modified temperature controlled incubator. 2. Temperature distributions were recorded on cine film which was analysed to evaluate mean skin temperatures; these were subsequently compared with values obtained from multiple, weighted measurements from a thermocouple thermometer. In all cases, there was agreement to within +/- 0 . 6 degrees C. 3. Thermograms in thermo-neutral conditions (approximately 32 degrees C) showed a temperature distribution with the warmest skin overlying the central hot 'core' and temperatures falling towards the extremities. Temperature patterns in a cooler environment (approximately 28 degrees C) showed features due to the conductive or thermogenic nature of the structures underlying the skin. 4. Multiple skin temperature recordings made at two environmental temperatures were obtained from a further twelve infants. 5. Linear regression of skin temperature against rectal--environmental difference, performed for each of the measured sites, showed that the upper arm and, to a lesser extent, the upper thigh temperatures represented the mean value most closely. The upper abdomen and head were both warmer and less responsive to environmental change than the mean skin temperature. These findings were supported by the thermographic observations.

Natural convection around the human head.

1. Factors determining the convective flow patterns around the human head in 'still' conditions are discussed in relation to body posture. 2. The flow patterns have been visualized using a schlieren optical system which reveals that the head has a thicker 'insulating' layer of convecting air in the erect posture than in the supine position. 3. Local convective and radiative heat transfer measurements from the head have been using surface calorimeters. These results are seen to be closely related to the thickness of the convective boundary layer flows. 4. The total convective and radiative heat loss from the head of a subject in the erect and supine position has been evaluated from the local measurements. For the head of the supine subject the heat loss was found to be 30% more than when the subject was standing.

Forced convection around the human head.

1. The parameters determining the forced convective heat loss from a heated body in an air stream are outlined. 2. Local forced convective heat transfer distributions around the human head and a heated vertical cylinder at various wind speeds in a climatic chamber have been found to be similar and related to the aerodynamic flow patterns. 3. From the local convective coefficient distribution, values for the overall convective coefficient h-c at various wind speeds have been evaluated. These are seen to agree closely with existing whole body coefficients determined by other methods.

Clothing for use in clean-air environments.

Disposable plastic two-piece suits were compared with conventional cotton suits, gowns, and plastic aprons by nurses in a burns unit. The plastic suits allowed fewer micro-organisms to be dispersed into the environment than the other garments but were less comfortable.

Electronic particle counting for evaluating the quality of air in operating theatres: a potential basis for standards?

Airborne particle counting in eight size ranges (0.5- greater than 20 microns), by computerized electronic equipment, was compared with the numbers of bacteria-carrying particles (BCP) assessed by slit sampling in ultra-clean and turbulently ventilated operating theatres. In the ultra-clean theatre the number of particles of 5-7 microns size range correlated with BCP while peaks in the numbers of particles less than 3 microns and greater than 15 microns corresponded with activity. Comparative relationships also occurred in the turbulently ventilated theatre but the use of this equipment in that environment cannot yet replace counts of airborne bacteria. We consider that electronic particle counting in the 0-20 microns size range may be used to judge the performance of a clean air operating theatre distribution system, including efficiency and integrity of the filter/seal systems and the presence or absence of entrainment of bacteria and other particles. The sampling techniques and analysis of particle concentration results described here may be a suitable basis for standards.