Showing papers by "RMIT University published in 1990"

Laser in situ keratomileusis.

Abstract: A new laser refractive procedure is being developed in a rabbit model. With a modified microkeratome, central corneal flaps were created. An ArF excimer laser was used to produce 3-mm-diameter circular ablations on the central part of the exposed stromal bed. One group of animals was sacrificed immediately postoperatively, and both the dissected and ablated areas were studied using scanning electron microscopy. A second group of animals was sacrificed 4 weeks postoperatively. In this group, the subsequent healing of the corneas was studied using light microscopy. At 3 days, the wounded stromal areas showed some degree of haze. Haze was progressively reduced over 1 month, but it could be still discerned biomicroscopically. A hemicircular opacification corresponding to the flap edges was also apparent on slit-lamp examination. Microscopic observation showed that the epithelium was normal, except at the flap margins, where it was thickened. An increased number of keratocytes was observed in the interface between the flap stroma and the ablated area. The procedure might induce stable corneal changes because of the preservation of the anterior layers of the cornea.

The Constitution of Poverty: Toward a Genealogy of Liberal Governance

Abstract: The discourse of the poor the problem of idleness the policing of the poor population, subsistence, poverty the Malthusian effect from morality to economy the moral economy of Adam Smith the condition of poverty pauperism and the labour-market pauper-land the mechanisms of prevention.

Human circadian rhythms and exercise.

Abstract: Many biological functions change cyclically over a 24-h period, such cycles being referred to as circadian rhythms. The major rhythms of relevance to examine performance are those of body temperature and the sleep-wake cycle. Many components of exercise performance are closely related to the body temperature curve which peaks in the early evening. Exercise with predominantly neuromotor and cognitive components depend also on the underlying sleep-wake cycle. Some performance measures are subject to ultradian cycles and show a transient decline in the early afternoon. Optimal time of day for exercise is determined not just by endogenous rhythms but also by the nature and intensity of exercise, the population concerned, environmental conditions, and individual phase types. Environmental factors impinging on circadian rhythms include light, heat, air ionization, activity and eating patterns, and social activities. Endogenous rhythms are desynchronized when perturbed by nocturnal shift work or time-zone transitions. Coping with desynchronosis involves behavioral, dietary, or pharmacological treatments. Sleep loss interacts with circadian rhythmicity but affects cognitive function more so than gross motor actions. The existence of self-sustaining rhythms should be recognized by athletic practitioners, sports scientists concerned with experimental work and fitness testing, sports injury specialists, and sports organizers concerned with the travel plans of athletes.

Clinical teaching in physical therapy: student and teacher perceptions.

Abstract: Many practicing physical therapists participate in the most crucial phase of a student's education by serving as Clinical Instructors. The purposes of this study were to identify the clinical teaching behaviors perceived as most effective and most hindering by students and CIs and to compare the response rates of students in bachelor's and master's degree programs. A published 58-item questionnaire was completed by 172 participants from eight physical therapy education programs. The results were analyzed by multivariate analysis of variance. The perceived most helpful teaching behaviors pertained to providing information through feedback. The perceived most hindering behaviors were intimidating questioning and correcting student errors in the presence of patients. The different student and CI ratings for the item "leaves student alone until asked to supervise" has important ethical and educational implications. Master's and bachelor's degree students' ratings differed significantly on four teaching behaviors. Different instructional methods might be necessary for educating these students.

Prevalence of a transferable SHV-5 type beta-lactamase in clinical isolates of Klebsiella pneumoniae and Escherichia coli in Greece.

Abstract: Analysis with a double-disc synergy test (DDST) of clinical isolates of Klebsiella pneumoniae and Escherichia coli during the period October 1988-September 1989 revealed that 24% of the former and 4% of the latter, mainly isolated from urine, possessed an extended-spectrum beta-lactamase. During this period no DDST was positive for isolates of other enterobacterial species. Transfer of ceftazidime resistance was demonstrated from six K. pneumoniae and two E. coli isolates resistant to third generation cephalosporins and aztreonam. Apart from one strain of K. pneumoniae, these strains harboured self-transferable multiresistance plasmids (c. 91 kb) with closely related EcoRI, HindIII, AvaII and PstI restriction patterns. These plasmids encoded an extended-spectrum beta-lactamase that conferred an unusually high level of resistance to ceftazidime and aztreonam (MIC greater than or equal to 64 mg/l). This enzyme had a pI of 8.2 and a substrate profile similar to that of the SHV-5 enzyme isolated initially in Chile, and later in France (CAZ-4). The remaining K. pneumoniae isolate harboured a transmissible multiresistance plasmid (c. 182 kb) that encoded the widely distributed SHV-2 enzyme. The resistance to cefoxitin that was observed in some of these strains was associated with outer membrane protein alterations.

Antioxidant effect of naturally occurring furan fatty acids on oxidation of linoleic acid in aqueous dispersion

Abstract: Naturally occurring furan fatty acids were synthesized and their antioxidant activity has been studied during the oxidation of linoleic acid in the phosphate buffer, pH 6.9, in the dark. The extent of the oxidation was followed both by the accumulation of conjugated diene and by the measurement of the residual amounts of linoleic acid. The tetra-alkylsubstituted furan fatty acids were found to suppress the oxidation. The trialkylsubstituted compound also showed antioxidant activity, being about 50% as effective as the tetra-alkylsubstituted ones. The di-alkylsubstituted one revealed no significant activity. The antioxidant activity of furan fatty acids depended on the number of substituents on the furan ring. Therefore, a tetra-alkylsubstituted furan ring may be necessary for the antioxidant action of furan fatty acids. The tetra-alkylsubstituted furan fatty acids reduced 1,1-diphenyl-2-picrylhydrazyl, reacted with the peroxyl radical generated from the thermal decomposition of a radical initiator, 2,2′-azobis(2-amidinopropane)hydrochloride (AAPH), and also suppressed the AAPH-induced oxidation of linoleic acid, indicating that, by scavenging, the peroxyl radical furan fatty acids inhibit the oxidation.

Adherence measured by microtiter assay as a virulence marker for Staphylococcus epidermidis infections.

Abstract: Staphylococcus epidermidis strains isolated from clinical sources showed a wide range of abilities to adhere to glass and plastic materials. The degree of adherence depended on a number of factors, most notably, the composition of the growth medium. Adherence was enhanced by the addition of glucose or oleic acid to the growth medium and inhibited by serum. We have demonstrated a statistically significant association between the quantitative assessment of adherence to polystyrene tissue culture plates and clinical relevance. No such association was found when adherence was assessed by the qualitative adherence assay. Possible new approaches for assessing the clinical relevance of coagulase-negative staphylococcal isolates are discussed.

The application of SAXS to determine the fractal properties of porous carbon−based materials

Abstract: A simple derivation of Bale and Schmidt's equation for the intensity of X-rays scattered through small angles (SAXS) by a porous solid with a fractal surface is given. This expression is then used in conjunction with experimental SAXS data to estimate the surface fractal dimension, D, of a wide range of porous, carbon-based solids. The measured values of D vary over virtually the whole theoretically allowable range. Further, we show that for a black coal sample both the fractal dimension and the extent of the surface are a function of the degree of oxidation of the coal sample. Thus, this method may be used to follow processes in porous solids and, given appropriate apparatus, the technique could be adapted to follow such processes in situ.

Postural control in standing following stroke: test-retest reliability of some quantitative clinical tests.

Abstract: Despite their importance to stroke rehabilitation, appropriate clinical tests of postural control in standing appear to be inadequately developed. Several quantitative clinical tests, therefore, were constructed. These tests were used to measure functionally relevant aspects of postural control in standing in 24 stroke patients within a mean time interval of two months following a cerebrovascular accident. Subjects were tested in two stance positions (step and parallel) for five tasks that assessed their ability to withstand perturbations produced by self-generated body movements during functional activities. Intrasession reliability coefficients were very high ( r = .94–.99). Intersession reliability coefficients were also high ( r = .85–.94). Because the test battery requires minimal training and equipment, it can be easily applied in the clinical setting. The high reliability obtained justifies further evaluation of these tests, which appear to be very promising for use in stroke rehabilitation.

A Signature File Scheme Based on Multiple Organizations for Indexing Very Large Text Databases.

Abstract: A new signature file method for accessing information from large databases containing both formatted and free text data is presented. The new method, called the multiorganizational scheme is proposed for indexing very large databases containing hundreds of thousands or possibly millions of records. With this method, records are grouped into blocks and signatures are formed for each block of records. These signatures are stored in a block descriptor file using a storage device called the bit slice organization. By forming multiple block descriptor files, each based on a possibly different grouping of records into blocks, it is possible to efficiently determine record matches on query. Both computational results based on a mathematical model as well as experimental results using a library database are presented. These results show that the method provides effective access to large text databases. © 1990 John Wiley & Sons, Inc.

Changes in stature following drop jumping and post-exercise gravity inversion.

Abstract: Spinal shrinkage, measured by changes in stature, is used as an index of spinal loading as alterations reflect changes in intervertebral disc height. Shrinkage induced by various physical activities may be reversed using gravity inversion. The present purpose was to examine the shrinkage induced by a drop jumping regimen and evaluate gravity inversion post-exercise. Eight males, aged 20-31, performed two separate experimental protocols, each on different dates at 1400 h. Subjects stood for 30 min before undertaking an exercise regimen, consisting of five sets of five drop jumps from a height of 1 m, rebounding over a hurdle 0.5 m high. For 20 min, directly following the exercise regimen, subjects on one occasion stood and on a second occasion undertook gravity inversion. Shrinkage was monitored for 40 min after this post-exercise treatment. The stadiometer used to measure shrinkage was accurate to 0.05 mm. The exercise regimen caused a mean shrinkage of 1.68 and 1.81 mm for the two testing sessions. Post-exercise inversion and standing for 20 min increased stature by 5.18 and 0.76 mm, respectively (P less than 0.01). The 40-min standing period following inversion caused a rapid loss in stature (4.07 mm). At 30 min into this recovery period, there was no significant difference in shrinkage for either of the regimens. Results suggest that effects of an inversion treatment are short-lasting.

Resistance mechanisms of multiresistant serotype 012 Pseudomonas aeruginosa isolated in Europe

Abstract: Serotype 012 Pseudomonas aeruginosa resistant to gentamicin (MIC greater than 4 mg/l) and carbenicillin (MIC greater than 128 mg/l) occur widely in Europe and are homogeneous in their phenotypic and genetic properties. It has been suggested that a single multiresistant strain of this serotype has become widespread. This study examined the resistance mechanisms present in multiresistant serotype 012 P. aeruginosa isolates from Austria, Belgium, France, Greece, Italy, Holland, West Germany and the UK. Disseminated isolates produced a PSE-1 type beta-lactamase, correlating with their resistance to the known substrates of this enzyme (carbenicillin, azlocillin and cefsulodin). These isolates also reacted with gene probes for the aminoglycoside modifying enzymes AAC(6')I and ANT(3'). The probe for AAC(6')I is known to cross-react with the gene for AAC(6')II. The fact that the organisms were resistant to netilmicin, gentamicin, sisomicin and tobramycin, but less so to amikacin, suggested that the latter enzyme was produced rather than AAC(6')I. PSE-1 beta-lactamase and the gene for AAC(6')I/AAC(6')II were absent from the International Antigenic Typing Scheme 012 reference strain, which was sensitive to beta-lactams and aminoglycosides, and also from a multiresistant serotype 012 strain isolated at a London burns unit in 1987. These organisms have been shown previously to be distinct from the disseminated multiresistant strain in their phenotypic properties. Two 012 isolates appeared to have additional resistance determinants to amikacin and isepamicin.

Expression of IGF-I and IGF-II genes in the adult rat eye.

Abstract: We have investigated the transcription of IGF-I and IGF-II genes in the adult rat eye. Each eye was dissected into cornea, lens, sclera+choroid+pigment epithelium, and neural retina. Total cellular RNA was isolated from each of these tissues. Northern blot analysis using rat coding region cDNA probes revealed the presence of IGF-I and IGF-II specific transcripts in the retina and the sclera but not in the lens and cornea. Retina demonstrated the highest level of IGF-I and IGF-II expression. Our results suggest autocrine and paracrine effects of the IGFs and their possible involvement in normal eye physiology as well as in the pathogenesis of certain eye diseases.

The risks and benefits of exercise during pregnancy

Abstract: There are benefits as well as risks associated with physical activity in all individuals, but there are some special medical considerations for the pregnant woman. The purpose of this article is to review the possible risks and benefits of exercise during pregnancy as presented in the literature, and to provide appropriate recommendations. There are some potential risks to the fetus resulting from maternal exercise including hypoxia, hyperthermia, and abnormal heart rate changes. The benefits, however, appear to outweigh the risks when they are minimized by prescribing appropriate exercises and using recommended precautions. Because human studies on exercise during pregnancy are currently limited, exercise prescriptions should be conservative. Swimming, biking, and aerobic walking are not associated with reported problems. Moderate aerobic exercise is safe provided the pregnancy is known to be normal. Contraindications to aerobic exercise during pregnancy include conditions that limit cardiorespiratory reserves. If a woman has been participating in an exercise program before gestation, she may be encouraged to continue the program at a moderate level if her pregnancy is normal.

Ion-beam-induced amorphization and dynamic annealing processes in silicon

Abstract: Amorphization of (100) silicon has been studied during elevated-temperature implantation with keV heavy ions. The amorphization process is very sensitive to the balance between defect production and annihilation rates, the latter resulting from dynamic annealing during ion bombardment. Amorphous-phase production is shown to depend critically on the ion dose rate. Further measurements have indicated that the amorphous phase can be difficult to nucleate at elevated temperatures, requiring the presence of existing interfaces, surfaces or crystal defects to provide appropriate nucleation sites.

Phenylbiguanide not phenyldiguanide is used to evoke the pulmonary chemoreflex in anaesthetized rabbits.

Abstract: The pulmonary chemoreflexes evoked by phenylbiguanide (PBG), phenyldiguanide (PDG), phenylguanidine (PG) and 5-hydroxytryptamine (5-HT) have been investigated in the pentobarbitone-anaesthetized rabbit. The rank order of potency was 5-HT greater than PBG greater than PG greater than PDG. The responses evoked by all agonists were antagonized by pre-treatment with the selective 5-HT3 receptor antagonist MDL 72222, suggesting that their reflex effects are mediated by 5-HT3 receptors located on pulmonary vagal afferents. Furthermore, considering the low potency and long injection response time of PDG compared to PBG, we conclude that previous workers have used PBG and not PDG to identify non-myelinated pulmonary vagal afferents and to evoke the pulmonary chemoreflex.

Dental conditions in patients with bipolar disorder on long-term lithium maintenance therapy.

Abstract: Bipolar disorder (manic depressive disease) affects 1% of the United States population. These persons suffer from episodes of extreme elation followed by long periods of depression. Dental screening examinations of 40 patients consecutively admitted to the medical center with this diagnosis were performed. Poor oral hygiene, accumulations of supragingival and subgingival calculus, extensive dental caries, and numerous missing teeth were commonly identified. The majority of patients with bipolar disorder are treated with lithium carbonate. The physiological effects of lithium, and its interaction with drugs used in dentistry are reviewed, and disease-specific modifications in dental treatment are recommended.

From school to higher education in Australia

Abstract: This paper addresses the question of why young people go on from school to higher education in Australia. A person-situation interactionist theory to explain decisions taken in the matter is developed, and in the light of this theory a model to predict entry to higher education is advanced. The model is tested using data from separate studies in two Australian States, Victoria and Queensland. Results of bivariate and logistic regression analyses are generally consistent with expectations from the model. Certain interactive effects of variables in the model upon entry to higher education are reported.

Comparison of the effect of argon and hydrogen ion bombardment on the diamond (100) surface as studied by AES and EELS

Abstract: The influence of 15 keV argon and hydrogen ion bombardment on the diamond (100) near-surface region is reported Based on a comparison between the C(KLL) Auger and EEL spectra of different carbon allotropes it was possible to determine that irradiation doses of 16 × 1015 and 16 × 1016 H + 2 cm 2 at 15 keV were found to produce an amorphous surface region By contrast Ar+ irradiation at the same dose and energy was found to induce a surface region rich in graphite-like sp2 bonds

The Use of Momentary Time Sampling and Partial Interval Recording in Behavioural Research

Abstract: The inherent properties of momentary time sampling (MTS) and partial interval recording (PIR) are examined. Findings derived from computer simulation investigations are discussed in terms of the mode of operation of the two time-sampling techniques. It is seen that the advantage of MTS is that it can, under certain restricted circumstances, estimate absolute duration of behaviour occurring. The important disadvantage of MTS is that it is relatively insensitive when estimating degree of change of behaviour. In contrast, although PIR cannot accurately measure absolute duration it is more sensitive to behaviour change than is MTS. It is concluded that the practitioner who wishes to use one of these methods of time sampling must carefully consider the aims and possible effects of the investigation before deciding which method to use.

Transformation of animal cells with human T-cell leukemia virus type II.

Abstract: Human T-cell leukemia virus type II (HTLV-II) was tested for its ability to transform normal animal cells. The HTLV-II-infected human T-cell line, HTLV-IIA was lethally X-irradiated and cocultivated with normal leukocytes of rabbit and crab-eating monkey and spleen cells of hamster. The transformed cell lines, designated Ra-IIA, Si-IIA and Ham-IIA, were established. These cell lines were shown to be infected with HTLV-II by the polymerase chain reaction method combined with the digoxigenin-enzyme-linked immunosorbent assay method. These cell lines were examined for viral antigens by the indirect immunofluorescence method. Although the cytoplasma of over 90% of the cells of Si-IIA cell line was brilliantly stained, Ra-IIA and Ham-IIA cells were not stained. Electron microscopy of cells of the Si-IIA line revealed C-type virus particles in the extracellular spaces.

Micro-centrifugation of human spermatozoa: its effect on fertilization of hamster oocytes after micro-insemination spermatozoal transfer

Abstract: Micro-centrifugation (MC) at 6500 r.p.m. (3352 g) has not been used previously for spermatozoal concentration and subsequent fertilization. We investigated MC for micro-insemination spermatozoal transfer (MIST) of human spermatozoa from normal donors into hamster oocytes. MC resulted in reduced penetration of hamster oocytes, both after MIST [77.4% (41/53) versus 87.8% (43/49) for control; NS] and after exposure to zona-free hamster oocytes [60.8% (79/130) versus 72.7% (88/121) for control; P less than 0.05]. However, MIST under the zona resulted in better incorporation of sperm nuclei when compared with zona-free hamster oocytes, for spermatozoa exposed to micro-centrifugation (77.4 versus 60.8%, P less than 0.05) and controls (87.8 versus 72.7%, P less than 0.05). Polyspermy was higher after MIST [22.0% (9/41) versus 13.9% (11/79); NS] for MC+, and [25.6% (11/43) versus 13.6% (12/88); NS] for MC-. We conclude that MC does have a negative, but minimal effect on the fertility of human spermatozoa with respect to hamster oocytes.