Determinants of elephant spatial use, habitat selection and daily movement patterns in Hluhluwe-iMfolozi Park.

Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.The ecological role of large herbivores is increasingly recognized due to their ability to influence ecosystem functioning and their impacts on faunal and floral assemblages. Knowledge on the determinants of spatial utilization is crucial towards the successful management of these species according to objectives set for the conservation of biodiversity. While numerous studies have investigated the factors influencing the movements and habitat preferences of large northern hemisphere herbivores, few have focused on members of the African megaherbivore guild. In the context of fenced reserves, elephants have been implicated in the degradation of habitat resulting in negative impacts on biodiversity. Using a kernel analysis approach, I calculated home range size and utilization distributions for five separate herds from an elephant population in Hluhluwe-iMfolozi Park and examined possible determinants. I explored differences in utilization intensity between herds and seasons by comparing the rugosity of utilization distributions. I used a utilization distribution-weighted composition analysis to determine seasonal habitat preferences within the home range and examined the factors influencing daily movement characteristics within different habitats in different seasons. Substantial variation in home range size and location, utilization intensity, habitat preferences and movement responses was evident between herds. Spatial and temporal variation in resource distribution and intra-specific competition explained differences in home range size and utilization intensity. Larger herds underwent more fission-fusion events than small herds, possibly due to resource scarcity and greater competitive interactions. Elephants preferred greener habitats during the dry season and appeared to conform to optimal foraging principles. They utilized forest habitats more than others, selected larger patches with high densities of favoured food items and included greater proportions of common woody species in their diet. Large groups foraged close to rivers in the wet season and appeared to broaden foraging choices in the dry season by moving further away. Restricted displacements in the early morning and evening suggested crepuscular foraging activity while greater displacements at midday could not be explained by the need for water. This study highlights the importance of considering variation in animal movements and habitat utilization in overall conservation planning and when evaluating threats to sensitive habitats, particularly in fenced protected areas

Regulation of nitrogen metabolism in vibrio alginolyticus

Bibliography: pages 125-135.Aerated cultures of Vibrio alginolyticus produced histidase at 30°C but production of histidase was repressed by either incubation at 37°C or a lack of oxygen. A similar regulation system by temperature and oxygen has been reported for collagenase and prntease production by V. alginolyticus (Hare et al., 1981). V. alginolyticus had identical growth rates at 30 and 37°C. The histidine-utilization (hut) enzymes were coordinately induced by histidine. The inducible nitrogen catabolic enzymes arginase, alanine dehydrogenase and histidase were not subject to nitrogen catabolite repression. Various amino acids and ammonium ions stimulated the production of histidase and arginase. Urocanase and formiminoglutamate hydrolase were repressed by nitrogen-containing compounds. Tryptophan, glutamine and isoleucine either repressed or had little effect on the production of histidase and urocanase. The hut enzymes and alanine dehydrogenase were sensitive to catabolite repression by glucose. The addition of (NH₄)₂SO₄ stimulated histidase production. Cyclic AMP did npt relieve repression by glucose. Catabolite repression by glucose of collagenase and protease production in V. alginolyticus was also not relieved by cyclic AMP (Reid, 1981; Long et al., 1981)

Proximate factors influencing dispersal in the social spider, Stegodyphus mimosarum (Araneae, Eresidae)

Thesis (M.Sc.)-University of Natal, Durban, 2002.Stegodyphus mimosarum Pavesi,1883 and S. dumicola Pocock, 1898 are two species of philopatric, inbred, permanently communal, non-territorial spiders that co-occur in parts of South Africa. The patchiness of colony distribution, limited dispersal capabilities and the observation of periodic, but rare mass dispersal events raised interest in factors influencing dispersal. The aim of this project was firstly, to determine which factors influence the spiders' readiness to leave a colony (two laboratory experiments), and secondly, to map nest dispersion in Weenen Nature Reserve, Kwa-Zulu Natal, and to use this to explain nest distribution. The first experiment assessed whether group size and variance in access to resources influenced the decision to disperse. Four colony sizes (8, 16,32 and 64) of S. mimosarum were established under a proportional feeding regime. I expected more spiders to leave larger colonies due to intra-group competition. However, there was no significant increase in the number of spiders leaving with increasing group size. Significantly more spiders left a colony during spring and when spiders were large. In the second experiment, I assessed whether the mean amount of food available, in liberally fed or starved colonies influenced the decision to disperse. Five colonies were fed daily on an abundance of prey items and five were starved. I expected more spiders to leave the starved colonies. However, a significant number of spiders left colonies where food was abundant. During a field survey nests were tagged within 40 plots of 50 m radius, and randomly. Retreat dimensions, height above ground, nest position, nearest neighbouring nests, and species were recorded. Nest status was tracked over six months to three years. I confirmed that nest height above ground was significantly higher for S. mimosarum. The two species differed in retreat volume and nearest neighbour distances. Most nests occurred on the northern aspect of trees. Few nests survived beyond three years, although many new nests were established. Access to resources influenced the decision to disperse. However, only well-fed (larger) spiders had the resources to relocate. Patchy nest distribution could be a consequence of nest site selection, short distance dispersal by budding and bridging, and long distance dispersal by ballooning

Late diagnosis among our ageing HIV population: a cohort study

INTRODUCTION: With the advent of combined antiretroviral therapy (cART), more people infected with HIV are living into older age; 22% of adults receiving care in the UK are aged over 50 years [1]. Age influences HIV infection; the likelihood of seroconversion illness, mean CD4 count and time from infection to development of AIDs defining illnesses decreases with increasing age. A UK study estimates that half of HIV infections in persons over 50 years are acquired at an age over 50 [2]. Studies exploring sexual practices in older persons have repeatedly shown that we cannot assume there is no risk of STI and HIV infection [3,4]. Physicians should be alert to risk of HIV even in the older cohort, where nearly half diagnoses are made late [2]. Local audit has demonstrated poor testing rates in the over 50's on the Acute Medical Unit. Late diagnosis (CD4<350) results in poorer outcomes and age confounds further; older late presenters are 2.4 times more likely to die within the first year of diagnosis than younger counterparts [2]. MATERIALS AND METHODS: A retrospective case notes review was conducted of all patients aged 60 years and over attending HIV clinic in the last 2 years. Outcomes audited included features around diagnosis; age, presentation, missed testing opportunities and CD4 count at diagnosis. RESULTS: Of the current cohort of 442 patients, 34 were over 60 years old (8%). Age at diagnosis in this group ranged from 36 to 80 years, mean 56.6 years. Presentation triggers included opportunistic infections or malignancies (n=10), constitutional symptoms (n=6), diagnosis of another STI (n=4), seroconversion illness (n=2), partner status (n=3). Eight patients were diagnosed through asymptomatic screening at Sexual Health. We identified missed opportunities in five patients who were not tested despite diagnoses or symptoms defined as clinical indicators for HIV. Half of older patients had a CD4 count of <200 at diagnosis. CONCLUSIONS: It is imperative that general medical physicians and geriatricians are alert to enquiring about risk and testing for HIV where clinical indicators are present, irrespective of age. The oldest patient in the cohort was diagnosed with HIV aged 80 years. All patients with missed opportunities for testing were over 47 years old

Convalescent plasma in patients admitted to hospital with COVID-19 (RECOVERY): a randomised controlled, open-label, platform trial

SummaryBackground Azithromycin has been proposed as a treatment for COVID-19 on the basis of its immunomodulatoryactions. We aimed to evaluate the safety and efficacy of azithromycin in patients admitted to hospital with COVID-19.Methods In this randomised, controlled, open-label, adaptive platform trial (Randomised Evaluation of COVID-19Therapy [RECOVERY]), several possible treatments were compared with usual care in patients admitted to hospitalwith COVID-19 in the UK. The trial is underway at 176 hospitals in the UK. Eligible and consenting patients wererandomly allocated to either usual standard of care alone or usual standard of care plus azithromycin 500 mg once perday by mouth or intravenously for 10 days or until discharge (or allocation to one of the other RECOVERY treatmentgroups). Patients were assigned via web-based simple (unstratified) randomisation with allocation concealment andwere twice as likely to be randomly assigned to usual care than to any of the active treatment groups. Participants andlocal study staff were not masked to the allocated treatment, but all others involved in the trial were masked to theoutcome data during the trial. The primary outcome was 28-day all-cause mortality, assessed in the intention-to-treatpopulation. The trial is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936.Findings Between April 7 and Nov 27, 2020, of 16 442 patients enrolled in the RECOVERY trial, 9433 (57%) wereeligible and 7763 were included in the assessment of azithromycin. The mean age of these study participants was65·3 years (SD 15·7) and approximately a third were women (2944 [38%] of 7763). 2582 patients were randomlyallocated to receive azithromycin and 5181 patients were randomly allocated to usual care alone. Overall,561 (22%) patients allocated to azithromycin and 1162 (22%) patients allocated to usual care died within 28 days(rate ratio 0·97, 95% CI 0·87–1·07; p=0·50). No significant difference was seen in duration of hospital stay (median10 days [IQR 5 to >28] vs 11 days [5 to >28]) or the proportion of patients discharged from hospital alive within 28 days(rate ratio 1·04, 95% CI 0·98–1·10; p=0·19). Among those not on invasive mechanical ventilation at baseline, nosignificant difference was seen in the proportion meeting the composite endpoint of invasive mechanical ventilationor death (risk ratio 0·95, 95% CI 0·87–1·03; p=0·24).Interpretation In patients admitted to hospital with COVID-19, azithromycin did not improve survival or otherprespecified clinical outcomes. Azithromycin use in patients admitted to hospital with COVID-19 should be restrictedto patients in whom there is a clear antimicrobial indication

Tocilizumab in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial

Background: In this study, we aimed to evaluate the effects of tocilizumab in adult patients admitted to hospital with COVID-19 with both hypoxia and systemic inflammation. Methods: This randomised, controlled, open-label, platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]), is assessing several possible treatments in patients hospitalised with COVID-19 in the UK. Those trial participants with hypoxia (oxygen saturation &lt;92% on air or requiring oxygen therapy) and evidence of systemic inflammation (C-reactive protein ≥75 mg/L) were eligible for random assignment in a 1:1 ratio to usual standard of care alone versus usual standard of care plus tocilizumab at a dose of 400 mg–800 mg (depending on weight) given intravenously. A second dose could be given 12–24 h later if the patient's condition had not improved. The primary outcome was 28-day mortality, assessed in the intention-to-treat population. The trial is registered with ISRCTN (50189673) and ClinicalTrials.gov (NCT04381936). Findings: Between April 23, 2020, and Jan 24, 2021, 4116 adults of 21 550 patients enrolled into the RECOVERY trial were included in the assessment of tocilizumab, including 3385 (82%) patients receiving systemic corticosteroids. Overall, 621 (31%) of the 2022 patients allocated tocilizumab and 729 (35%) of the 2094 patients allocated to usual care died within 28 days (rate ratio 0·85; 95% CI 0·76–0·94; p=0·0028). Consistent results were seen in all prespecified subgroups of patients, including those receiving systemic corticosteroids. Patients allocated to tocilizumab were more likely to be discharged from hospital within 28 days (57% vs 50%; rate ratio 1·22; 1·12–1·33; p&lt;0·0001). Among those not receiving invasive mechanical ventilation at baseline, patients allocated tocilizumab were less likely to reach the composite endpoint of invasive mechanical ventilation or death (35% vs 42%; risk ratio 0·84; 95% CI 0·77–0·92; p&lt;0·0001). Interpretation: In hospitalised COVID-19 patients with hypoxia and systemic inflammation, tocilizumab improved survival and other clinical outcomes. These benefits were seen regardless of the amount of respiratory support and were additional to the benefits of systemic corticosteroids. Funding: UK Research and Innovation (Medical Research Council) and National Institute of Health Research

Convalescent plasma in patients admitted to hospital with COVID-19 (RECOVERY): a randomised controlled, open-label, platform trial

Background: Many patients with COVID-19 have been treated with plasma containing anti-SARS-CoV-2 antibodies. We aimed to evaluate the safety and efficacy of convalescent plasma therapy in patients admitted to hospital with COVID-19. Methods: This randomised, controlled, open-label, platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]) is assessing several possible treatments in patients hospitalised with COVID-19 in the UK. The trial is underway at 177 NHS hospitals from across the UK. Eligible and consenting patients were randomly assigned (1:1) to receive either usual care alone (usual care group) or usual care plus high-titre convalescent plasma (convalescent plasma group). The primary outcome was 28-day mortality, analysed on an intention-to-treat basis. The trial is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936. Findings: Between May 28, 2020, and Jan 15, 2021, 11558 (71%) of 16287 patients enrolled in RECOVERY were eligible to receive convalescent plasma and were assigned to either the convalescent plasma group or the usual care group. There was no significant difference in 28-day mortality between the two groups: 1399 (24%) of 5795 patients in the convalescent plasma group and 1408 (24%) of 5763 patients in the usual care group died within 28 days (rate ratio 1·00, 95% CI 0·93–1·07; p=0·95). The 28-day mortality rate ratio was similar in all prespecified subgroups of patients, including in those patients without detectable SARS-CoV-2 antibodies at randomisation. Allocation to convalescent plasma had no significant effect on the proportion of patients discharged from hospital within 28 days (3832 [66%] patients in the convalescent plasma group vs 3822 [66%] patients in the usual care group; rate ratio 0·99, 95% CI 0·94–1·03; p=0·57). Among those not on invasive mechanical ventilation at randomisation, there was no significant difference in the proportion of patients meeting the composite endpoint of progression to invasive mechanical ventilation or death (1568 [29%] of 5493 patients in the convalescent plasma group vs 1568 [29%] of 5448 patients in the usual care group; rate ratio 0·99, 95% CI 0·93–1·05; p=0·79). Interpretation: In patients hospitalised with COVID-19, high-titre convalescent plasma did not improve survival or other prespecified clinical outcomes. Funding: UK Research and Innovation (Medical Research Council) and National Institute of Health Research