Intracellular immunohistochemical detection of tetrodotoxin in Pleurobranchaea maculata (Gastropoda) and Stylochoplana sp. (Turbellaria)

Tetrodotoxin (TTX), is a potent neurotoxin targeting sodium channels that has been identified in multiple marine and terrestrial organisms. It was recently detected in the Opisthobranch Pleurobranchaea maculata and a Platyhelminthes Stylochoplana sp. from New Zealand. Knowledge on the distribution of TTX within these organisms is important to assist in elucidating the origin and ecological role of this toxin. Intracellular micro-distribution of TTX was investigated using a monoclonal antibody-based immunoenzymatic technique. Tetrodotoxin was strongly localized in neutral mucin cells and the basement membrane of the mantle, the oocytes and follicles of the gonad tissue, and in the digestive tissue of P. maculata. The ova and pharynx were the only two structures to contain TTX in Stylochoplana sp. Using liquid chromatography-mass spectrometry, TTX was identified in the larvae and eggs, but not the gelatinous egg cases of P. maculata. Tetrodotoxin was present in egg masses of Stylochoplana sp. These data suggest that TTX has a defensive function in adult P. maculata, who then invest this in their progeny for protection. Localization in the digestive tissue of P. maculata potentially indicates a dietary source of TTX. Stylochoplana sp. may use TTX in prey capture and for the protection of offspring

An Atomic Force Microscopy Nanoindentation Study of Size Effects in Face-Centered Cubic Metal and Bimetallic Nanowires

The enhancement of strength of nanoscale materials such as face-centered cubic metal nanowires is well known and arises largely from processes mediated by high energy surface atoms. This leads to strong size effects in nanoscale plasticity; ,smaller is stronger. Yet, other factors, such as crystalline defects also contribute greatly to the mechanical properties. In particular, twin boundaries, which are pervasive and energetically favorable defects in face-centered cubic metal nanowires, have been shown to greatly enhance the strength, furthermore this increase in strength has been shown to be directly influenced by the twin density. However, attempts to control the introduction of beneficial defects remains challenging. Additionally, even minor local variations in the crystalline structure or size of metal nanowires may have drastic effects on the yielding of metal nanowires, which are difficult to measure through tensile and bending tests. In this study, atomic force microscopy based nanoindentation techniques are used to measure the local plasticity of Ni-Au bimetallic as well as Cu and Ag metallic nanowires. In the first part of the thesis the hardness of bimetallic nanowires synthesized through template-assisted electrodeposition is measured and found to show significant size-effects. It was found that the nanoindentation hardness was governed by materials properties, the observed indentation size effects were dependent on geometrical factors. The second part of this thesis presents a methodology to control the crystal structure of Ag and Cu nanowires through direct electrodeposition techniques, which were tested directly as grown on the substrate to limit effects of pre-straining. Ag nanowires showed marked size-effects as well as two distinct modes of deformation which we attribute to the defects that arise during crystalline growth. We also show control of the surface microstructure in Cu nanowires which leads to strengths that are more than doubled compared to single crystalline Cu nanowires. Finally, we present support from classic crystal growth theory to justify that the observed plasticity in Ag and Cu nanowires is largely dependent on defects that are nucleated through changes in the growth environment

Preparing for the transition to professional work

This paper looks at the final outcome of a science degree program, and considers what happens when students leave university as graduates and the skills they have acquired (or should have acquired). In studying this area we are hampered by lack of data. To study the experience of the large numbers of students entering first year we have good data on students’ entry levels (HSC results and so on), on students’ demographic backgrounds and on their progress through university. This is available at our fingertips on most university computer systems. In contrast, data on graduates are much less extensive. Firstly, many departments do not keep information on their alumni, who are, in any case, spread far and wide. Graduates are no longer a captive audience and any data that are collected will be voluntary. One such source is the course experience questionnaire (CEQ), answered by students a few months after they finish their degree: about 70% of students complete the CEQ each year. In particular, there is no clear indication that students in science courses leave university with welldeveloped ‘generic skills’ such as concepts of ethics (professional or personal), sustainability, creativity, computing skills, information skills, communication skills, interpersonal skills and teamwork skills. This raises many questions: should we as science lecturers be teaching this material, should students be learning it as part of life, should graduates learn the skills on the job, should the careers services of the university be teaching these skills along with résumé writing? This paper also looks at research on students’ perceptions of their future work and career and the current research that is investigating the connections between these perceptions and their learning at university. We consider ways that professional work can be modelled in classroom activities so that students develop realistic ideas of the workforce and extend their range of proficiency in other areas

Reading Statistics

There has been a substantial increase in the cultural and academic diversity of commencing tertiary students over the previous decade. From 1990 to 2000 the total number of students in higher education increased by 43% (to just under 700,000), while the number of overseas students increased by a factor of four (to just under 100,000), raising the ratio to one-in-seven students (Department of Education, Science and Training, 2002). With this increase in number and cultural diversity comes an increase in their academic diversity. At the same time, changes in the nature and scope of professional work are placing an increasing demand on the range of skills, linguistic and numerical, that are needed by a successful graduate. A challenge for mathematics and statistics educators is the development of curriculum that addresses the language-related difficulties of language minority students, the numerical difficulties of students with diverse mathematical backgrounds, and enhances the learning outcomes for all students. This paper describes our approach to this challenge, based on our research in student conceptions of statistics and the language needs of professionals in the mathematical sciences, and embodied in the learning materials that we are currently developing. Australian government and professional bodies have recognised the importance of this area. A recent review with a scope of ‘the 15 years from 1995–2010’, finds ‘unequivocal evidence that, as an economic and social instrument, advanced mathematical services relying on the mathematical sciences are critically important to Australia’ (National Committee for Mathematics, 1996). Recent government initiatives have targeted declining interest, standards and resourcing in mathematics (see for example Thomas, 2000). Similarly, universities are moving towards the integration of ‘generic skills’ within the curriculum, loosely equating statistical study with a higher-level ‘numeracy’

Laboratory marker profile of patients with Juvenile Idiopathic Arthritis in a paediatric rheumatology outpatient clinic service at Tygerberg Hospital

Thesis (MMed)--Stellenbosch, 2020.ENGLISH ABSTRACT: Background: Juvenile idiopathic arthritis (JIA) is the most commonly occurring chronic rheumatic disease of childhood. The diagnosis is currently a clinical one with Rheumatoid factor and HLA-B27 antigen as the only laboratory markers included in the International League of Associations for Rheumatology’s classification (ILAR). Aim: The primary aim of the study was to examine the laboratory marker profile of patients with JIA at entry into the clinic. The secondary aim was to describe the distribution of the profile in the 7 JIA subgroups. Method: A retrospective, descriptive study was done at Tygerberg Hospital. It included all patients who met the diagnostic criteria (ILAR) for JIA seen at the paediatric rheumatology clinic between the clinic’s inception in 1995 to July 2017. Exclusion criteria were an age older than 16 years, HIV infection or another rheumatological condition. Results: A total of 165 patients were recorded, with an overall predominance of female gender (58.2%), however for the subgroups of Enthesitis Related JIA, Psoriatic JIA and unspecified JIA there was a higher male to female ratio. Polyarticular JIA at 39% made up the largest subgroup, of which 15.8% were classified as poly RF positive and 23.6% as poly RF negative, closely followed by Oligoarthritis JIA, which made up 23% and which also had the youngest median age of presentation at 5 years (IQR 2-8) and 31.4% had positive antinuclear antigen (ANA). ANA positivity across the other subgroups was 23% for poly RF positive, 7.9% for poly RF negative, 8% for systemic JIA, 5% enthesitis related JIA, 100% psoriatic JIA and none in the undifferentiated group. Some studies report up to 15% of the healthy population are low grade ANA positive. [1] Patients diagnosed with systemic JIA had significantly raised C-reactive protein (CRP) levels with a median of 150 ug/dL (IQR 95-205) with 50% having both a raised CRP and Erythrocyte sedimentation rate (ESR) with a median ESR 98 mm/hr (IQR 51-145). Furthermore 21.4% had a positive anti-streptolysin O titer (ASOT), 28% had raised Alanine aminotransferase (ALT) and all had raised platelet counts which is in keeping with the published literature of laboratory parameters indicative that systemic JIA is an autoinflammatory syndrome. For patients with Enthesitis related JIA, 53.8% tested positive for HLA-B27 antigen. Across the 7 subgroups the ASOT was positive in 12.7% of patients which is suggestive of a background burden of Streptococcal infection in some of our cohort. 79.4% of the study cohort had a normal BMI as defined by the WHO BMI Z score charts, with 9.1% of patients classified as underweight and 4.8% classified as obese. Polyarticular JIA, as the commonest subgroup in our cohort, was Rheumatoid factor negative predominant and systemic JIA demonstrated a significant inflammatory profile, with a significantly elevated CRP (P value 0.025) and elevated platelet counts, however not statistically significant. Nonspecific ASOT elevation was seen in 12.7% of patients, most commonly in the systemic JIA subgroup, followed by poly RF negative subgroup. ANA positivity was present in all subgroups, in varying percentages, except for the undifferentiated group where all patients tested had negative ANA. 9% of patients were underweight, 9% were overweight and 4.8% were obese. As nutrition is a critical determinant of immune responses, with both micro and macronutrient deficiency altering immunocompetence and increasing risk for infection, together with the knowledge that malnutrition is the most common cause of immunodeficiency worldwide, we need to consider the impact of malnutrition on the laboratory marker profile of patients due to immune modulation of nutrient deficiency. Conversely it is appreciated that overnutrition and obesity also contribute to an altered immunity. [2,3] Raised ASOT marker profile of our patients is suggestive of an associated Streptococcal infection burden. Baseline normal ranges of ASOT need to be established so that we may interpret the results in the context of our population where positive ranges in otherwise healthy patients may be higher. Further studies are needed to elucidate the impact of immune activation and the resultant effect on the local reference ranges of baseline autoantibodies, namely rheumatoid factor (RF) and anti-nuclear antibodies (ANA). Baseline normal ranges of ASOT need to be established so that we may interpret the results in the context of our population where positive ranges in otherwise healthy patients may well be higher."Geen opsomming beskikbaar."Master

Navigating the career transition from industry to academia

Transitions from ‘industry’ to ‘academia’ represent a unique type of career change. Although such transitions are becoming increasingly common in Australian universities and beyond, there is no coherent framework for making sense of the multiple and intersecting factors involved in these inter-domain movements. This form of occupational transition challenges the traditional and increasingly outdated conception of the linear academic tenure track. Thus, in order to revise the notion of the tenure track and gain a fuller understanding of these career trajectories, we must seek to understand the motivations for such occupational movements as well as the short-term, medium-term and long-term social, emotional and professional needs and preferences of practitioner-academics having made this transition. This article presents an attempt to re-think the imagery and language that have come to characterize this type of career movement as well as the attitudes within and between industry and academia. The authors advocate that transitions from industry to academia do not require the dismantling of linkages between the two fields, but rather are made more meaningful and effective when pre-existing professional and personal linkages are maintained and encouraged

An exploration of patients’ experience of nurses’ use of point-of-care information technology in acute care

The rapid introduction of technology into acute healthcare settings, specifically the presence of point-of-care health information technology at patients’ bedsides, is expected to impact patients’ healthcare experience by altering nurse-patient interactions. This research was a multi-method naturalistic pilot study designed to explore patients’ perception of their interactions with nurses using bedside point-of-care health information technology in acute care. Data were collected using observation, interviews and surveys. Twenty-four participants were purposefully recruited from medical and surgical wards, to capture variability in their self-reported confidence with information technology; 29% were not confident, 38% were somewhat confident and 33% were completely confident with information technology. Participants’ mean age was 68.6 years (SD 11.1) and 63% were male. Qualitative observation, interview and survey data showed some nurses directly involved patients and explained or demonstrated how the point-of-care health information technology was being used to complement and enhance their care; while others used the point-of-care health information technology as an electronic documentation tool without engaging their patients. Patients’ experiences of point-of-care health information technology differed with their self-reported confidence with information technology; those with complete information technology confidence were better at recognising the potential and opportunities for point-of-care health information technology to support self-directed care than those with less confidence using information technology. Some participants reported that the use of point-of-care health information technology impeded interpersonal communication with nurses. Participants recognised the benefits of point-of-care health information technology to support clinical practice but generally desired greater engagement with the nurses when they used the system

Influence of Pacing Strategy on Oxygen Uptake During Treadmill Middle-Distance Running

The oxygen uptake (V·O2) attained during a constant speed 800-m pace trial on a treadmill is less than the maximal V·O2 (V·O2max) in male middle-distance runners with a high V·O2max (i.e., > 65 ml · kg-1 · min-1). We therefore investigated whether the V·O2 attained was influenced by the pacing strategy adopted. Eight male middle-distance runners (age 25.8 ± 3.3 years; height 1.78 ± 0.10 m; mass 67.8 ± 4.7 kg) with a personal best 800-m time of 112.0 ± 3.3 s volunteered to participate. Subjects undertook a speed ramped progressive test to determine V·O2max and three 800-m pace runs to exhaustion all in a randomised order. The three 800-m pace runs included constant speed, acceleration, and race simulation runs. Oxygen uptake was determined throughout each test using 15-s Douglas bag collections. Following the application of a 30-s rolling average, the highest V·O2 during the progressive test (i.e., V·O2max) and the highest V·O2 during the 800-m pace runs (i.e., V·O2peak) were compared. For the eight runners, V·O2max was 67.2 ± 4.3 ml · kg-1 · min-1. V·O2peak was 60.1 ± 5.1 ml · kg-1 · min-1, 61.1 ± 5.2 ml · kg-1 · min-1, and 62.2 ± 4.9 ml · kg-1 · min-1, yielding values of 89.3 ± 2.4 %, 90.8 ± 2.8 %, and 92.5 ± 3.1 % V·O2max for the constant speed, acceleration and race simulation runs, respectively. Across runs, repeated measures ANOVA revealed a significant effect (p = 0.048). Trend analysis identified a significant linear trend (p = 0.025) with the % V·O2max attained being higher for the acceleration run than the constant speed run, and higher still for the race simulation run. These results demonstrate that in middle-distance runners a) pacing strategy influences the V·O2 attained, with a race simulation run elevating the V·O2 attained compared with other pacing strategies, and b) regardless of pacing strategy the V·O2 attained in an 800-m pace run on a treadmill is less than V·O2max

Community viral load and CD4 count distribution among people living with HIV in a South African Township: implications for treatment as prevention.

INTRODUCTION: The goals of scale-up of antiretroviral therapy (ART) have expanded from prevention of morbidity and death to include prevention of transmission. Morbidity and mortality risk are associated with CD4 count; transmission risk depends on plasma viral load (VL). This study aimed to describe CD4 count and VL distributions among HIV-infected individuals in a South African township to gain insights into the potential impact of ART scale-up on community HIV transmission risk. METHODS: A random sample of 10% of the adult population was invited to attend an HIV testing service. Study procedures included a questionnaire, HIV testing, CD4 count, and VL testing. RESULTS: One thousand one hundred forty-four (88.0%) of 1300 randomly selected individuals participated in the study. Two hundred sixty tested positive, giving an HIV prevalence of 22.7% [95% confidence interval (CI): 20.3 to 25.3]. A third of all HIV-infected individuals (33.5%, 95% CI: 27.8 to 39.6) reported taking ART. The median CD4 count was 417 cells per microliter (interquartile range, 285-627); 33 (12.7%, 95% CI: 8.9 to 17.4) had a CD4 count of ≤200 cells per microliter. VL measurements were available for 219 individuals (84.2%) and were undetectable in 72 (33.9%), >1500 copies per milliliter in 127 (58.0%) and >10,000 copies per milliliter in 96 (43.8%). Of those reporting they were receiving ART, 30.4% had a VL >1500 copies per milliliter compared with 58.0% of those reporting they were not receiving ART. CONCLUSIONS: A small proportion of those living with HIV in this community had a CD4 count of <200 cells per microliter; more than half had a VL high enough to be associated with considerable transmission risk. A substantial proportion of HIV-infected individuals remained at risk of transmitting HIV even after starting ART