To sterilise or disinfect--that is the question

Few hospitals have the in-house technology to sterilise heat and moisture sensitive reusable devices, yet the use of this type of equipment is increasing in all types of surgery. In general terms and because of limitations of existing technology, instruments and equipment have been divided into three categories based on the degree of risk of infection involved in their use: 1. Instruments and equipment which come into contact with intact skin must be cleaned before they are used. 2. Instruments and equipment which come into contact with non-sterile tissue (other than intact skin) must be disinfected before they are used. 3. Instruments and equipment which enter, or are capable of entering, the vascular system or tissue that would be sterile under normal circumstances must be sterilised before they are used. Unfortunately, some devices that should be sterilised are only disinfected in liquid chemical disinfectants. Traditional low-temperature sterilisation systems such as ethylene oxide (EtO) and low temperature steam and formaldehyde (LTSF) have many disadvantages and it is undoubtedly for this reason they have been relegated to a few specialist sterile service departments in the UK.     

Gas-liquid chromatography-mass spectrometry of hydroxy fatty acids as their methyl esters tert.-butyldimethylsilyl ethers

BACKGROUND: The objective of this paper is to illustrate the effect of a gap of 5 mm, an overlap of 5 mm and a perfect match on the dose distribution across the junction of tangential breast fields and adjacent supraclavicular and axillary fields. MATERIALS AND METHODS: For this purpose film dosimetry was applied to measure relative dose distributions in two sagittal planes in an anthropomorphic breast phantom having cork lungs, simulating a radiation therapy treatment of the breast and adjacent supraclavicular lymph nodes. Two different treatment techniques, an SSD match technique and a geometrically exact isocentric match technique, as routinely applied in the two institutes were examined. The three-dimensional treatment planning system of each institute was used to calculate the dose distribution in the match region of the supraclavicular fields and the two opposing tangential fields. The measured and calculated dose distributions were evaluated and compared along lines in two sagittal planes from the supraclavicular fields down to the tangential fields crossing the match planes. These dose distributions in the match region were extremely dependent on the set-up of the fields. RESULTS: Although the reproducibility of the film measurements was within 2%, it became clear that the set-up of the fields to achieve a gap of 5 mm, a perfect match or an overlap of 5 mm required a lot of attention, even when using a phantom. CONCLUSIONS: It can be concluded that in clinical practice, these set-up difficulties do influence the dose distribution in the match region much more than the systematic uncertainties in the dose calculation algorithms of the treatment planning systems and the type of treatment technique.     

Analytical solution using a pore diffusion model for a pseudoirreversible isotherm for the adsorption of basic dye on silica

An analytical solution for a two resistance mass transfer model explaining the adsorption of Astrazone Blue dye (Basic Blue 69) onto Sorbsil silica has been developed. The model includes a film mass transfer coefficient, k_f1 = 80 × 10⁻⁶cm·s−1, and an internal effective diffusivity, D_eff = 18×10⁻⁹cm²·s⁻¹ which controls the internal mass transport processes based on a pore diffusion mechanism.     

Serious infections due to Pseudomonas aeruginosa

Infections due to Ps. aeruginosa are a problem in the tropics as in other parts of the world. Over a four year period, 15 patients attending University College Hospital, Ibadan, were proved to have septicaemia due to this organism and 13 patients died rapidly as a direct result of the infection. The two patients who survived the acute episode had received immediate treatment with at least one antibiotic active against Ps. aeruginosa: a third patient, who received immediate appropriate antibiotic therapy, was already suffering from aplastic anaemia and died rapidly despite treatment. The remaining patients received inappropriate antibiotic therapy because pseudomonas infection was not suspected at the time the diagnosis of septicaemia was made. Patients most at risk appear to be the very young and those with pre-existing malignant or other conditions affecting the defence mechanisms of the body: it is suggested that routine initial management of such patients should include a blood culture, followed by immediate treatment with an antibiotic combination that includes at least one agent likely to be active against Ps. aeruginosa. The development of medical services can lead to the introduction of ophthalmic or other operations on tissues that are highly susceptible to infection before facilities are provided for the maintenance of a pathogen-free environment. Following an outbreak of eye infection after cataract extractions, carried out in an old and unsatisfactory theatre, wide-spread room contamination was demonstrated with the same strains of Ps. aeruginosa that had been responsible for the clinical infections. Chemical disinfection of the theatre floor failed to eliminate the organisms, although other experiments suggested that the drying effect of air-conditioning would be successful in this respect. The wisdom of introducing such operations before the provision of adequate facilities is seriously questioned.     

Changes in the secretion of growth hormone in severely injured persons (author's transl)

The secretion of growth hormone was studied in 25 severely injured persons during the adaptive and convalescent stage. The ages of the patients varied between 9--65 years. During the first few days after the trauma hormone concentrations rose to up to 7--15 times their normal upper limits (about 10 mU/l). In some cases the hormone levels subsequently fell to the lower limits of normal. No attempt was made to calculate average values and the reasons for the omission are stated. The results are discussed with reference to the metabolic condition of the severely injured persons.     

Compact range reflector analysis using the plane wave spectrumapproach with an adjustable sampling rate

An improved method for determining the test zone field of compact range reflectors is presented. The plane wave spectrum (PWS) approach is used to obtain the test zone field from knowledge of the reflector aperture field distribution. The method is particularly well suited to the analysis of reflectors with a linearly serrated rim for reduced edge diffraction. Computation of the PWS of the reflector aperture field is facilitated by a closed-form expression for the Fourier transform of a polygonal window function. Inverse transformation in the test zone region is accomplished using a fast Fourier transform (FFT) algorithm with a properly adjusted sampling rate (which is a function of both the reflector size and the distance from the reflector). The method is validated by comparison with results obtained using surface current and aperture field integration techniques. The performance of several serrated reflectors is evaluated in order to observe the effects of edge diffraction on the test zone fields     

Contractile cells of the kidney in primary glomerular disorders: an immunohistochemical study using an anti-alpha-smooth muscle actin monoclonal antibody

Mesangial cells of the renal glomerulus are thought to have contractile properties, resembling those of smooth muscle cells. Since actin synthesis in mesangial cells is increased in selected animal models of glomerulonephritis, we evaluated the expression of alpha-smooth muscle actin (ASMA), the principal actin isoform found in smooth muscle cells, in biopsy specimens from patients with primary glomerular disorders and in control tissues. Normal glomeruli and glomeruli in acute tubulointerstitial disorders showed few or no ASMA-positive cells in the glomeruli. In contrast, ASMA expression in mesangial cells was increased in minimal change disease, focal segmental glomerulosclerosis, mesangial proliferative glomerulonephritis, membranous glomerulonephritis, and immunoglobulin A nephropathy. In membranoproliferative glomerulonephritis and cryoglobulinemic glomerulonephritis both mesangial and capillary loop ASMA-positive cells were observed with a segmental distribution. In addition, ASMA-positive interstitial cells were seen in many biopsy specimens and often were increased in number in biopsy specimens showing early interstitial fibrosis and tubular atrophy. We conclude that ASMA synthesis in mesangial cells is upregulated in a variety of glomerular disorders, frequently associated with increased cell proliferation and mesangial matrix production. This phenotypic change may be an indicator of mesangial cell activation after injury and may have important pathophysiologic consequences.