RESUMEN
Determining the death burden for prioritising public health interventions necessitates detailed data on the causal pathways to death. Postmortem minimally invasive tissue sampling (MITS), incorporating histology, molecular and microbial culture diagnostics, enhances cause-of-death attribution, particularly for infectious deaths. MITS proves a valid alternative to full diagnostic autopsies, especially in low- and middle-income countries. In Soweto, South Africa (SA), the Child Health and Mortality Prevention Surveillance (CHAMPS) programme has delineated over 1 000 child and stillbirth deaths since 2017. This SA CHAMPS site supports advocating for the use of postmortem MITS as routine practice, for more granular insights into under-5 mortality causes. This knowledge is crucial for SA's pursuit of Sustainable Development Goal 3.2, targeting reduced neonatal and under-5 mortality rates. This commentary explores the public health advantages and ethicolegal considerations surrounding implementing MITS as standard of care for stillbirths, neonatal and paediatric deaths in SA. Furthermore, based on the data from CHAMPS, we present three pragmatic algorithmic approaches to the wide array of testing options for cost-effectiveness and scalability of postmortem MITS in South African state facilities.
Asunto(s)
Mortalidad del Niño , Nivel de Atención , Niño , Recién Nacido , Embarazo , Femenino , Humanos , Sudáfrica , Causas de Muerte , Mortinato , AutopsiaRESUMEN
Photosynthetic microorganisms have a wide range of biotechnical applications, through the application of their versatile metabolisms. However, their use in industry has been extremely limited to date, partially because of the additional complexities associated with their cultivation in comparison to other organisms. Strategies and developments in photobioreactors (PBRs) designed for their culture and applications are needed to drive the field forward. One particular area which bears examination is the use of strategies to separate solid- and hydraulic-residence times (SRT and HRT), to facilitate flow-through systems and continuous processing. The aim of this review is to discuss the various types of PBRs and methods which are currently demonstrated in the literature and industry, with a focus on the separation of HRT and SRT. The use of an efficient method of biomass retention in a PBR may be advantageous as it unlocks the option for continuous operation, which may improve efficiency, and improve economic feasibility of large-scale implementation of photosynthetic biocatalysts, especially where biomass is not the primary product. Due to the underexplored nature of the separation of HRT and SRT in reactors using photosynthetic microorganisms, limited literature is available regarding their performance, efficiencies, and potential issues. This review first introduces an overview into photosynthetic microorganisms cultivated and commonly exploited for use in biotechnological applications, with reference to bioreactor considerations specific to each organism. Following this, the existing technologies used for the separation of HRT and SRT in PBRs are explored. The respective advantages and disadvantages are discussed for each PBR design, which may inform an interested bioprocess engineer.
Asunto(s)
Reactores Biológicos , Fotobiorreactores , Fotosíntesis , BiomasaRESUMEN
PURPOSE: Pulmonary emboli (PE) contribute substantially to coronavirus disease 2019 (COVID-19) related mortality and morbidity. Immune cell-mediated hyperinflammation drives the procoagulant state in COVID-19 patients, resulting in immunothrombosis. To study the role of peripheral blood mononuclear cells (PBMC) in the procoagulant state of COVID-19 patients, we performed a functional bioassay and related outcomes to the occurrence of PE. Secondary aims were to relate this functional assay to plasma D-dimer levels, ventilation perfusion mismatch and TF expression on monocyte subsets. METHODS: PBMC from an ICU biobank were obtained from 20 patients with a computed tomography angiograph (CTA) proven PE and compared to 15 COVID-19 controls without a proven PE. Functional procoagulant properties of PBMC were measured using a modified fibrin generation time (MC-FGT) assay. Tissue factor (TF) expression on monocyte subsets were measured by flow cytometry. Additional clinical data were obtained from patient records including end-tidal to arterial carbon dioxide gradient. RESULTS: MC-FGT levels were highest in the samples taken closest to the PE detection, similar to the end-tidal to arterial carbon dioxide gradient (ETCO2 - PaCO2), a measurement to quantify ventilation-perfusion mismatch. In patients without proven PE, peak MC-FGT relates to an increase in end-tidal to arterial carbon dioxide gradient. We identified non-classical, CD16 positive monocytes as the subset with increased TF expression. CONCLUSION: We show that the procoagulant state of PBMC could aid in early detection of PE in COVID-19 ICU patients. Combined with end-tidal to ETCO2 - PaCO2 gradient, these tests could improve early detection of PE on the ICU.
Asunto(s)
COVID-19 , Embolia Pulmonar , Humanos , Leucocitos Mononucleares , Dióxido de Carbono , Estudios Prospectivos , Embolia Pulmonar/diagnóstico , PerfusiónRESUMEN
BACKGROUND: In South Africa (SA), district hospitals (DHs) have limited capacity to manage the high burden of traumatic injuries. Scaling up decentralised orthopaedic care could strengthen trauma systems and improve timely access to essential and emergency surgical care (EESC). Khayelitsha township in Cape Town, SA, has the highest trauma burden in the Cape Metro East health district. OBJECTIVES: The primary objective of this study was to describe the impact of Khayelitsha District Hospital (KDH) on acute orthopaedic services in the health district, with a focus on the volume and type of orthopaedic services provided without tertiary referral. METHODS: This retrospective analysis described acute orthopaedic cases from Khayelitsha and their management between 1 January 2018 and 31 December 2019. Orthopaedic resources and the proportion of cases referred to the tertiary hospital by all DHs in the Cape Metro East health district are described. RESULTS: In 2018 - 2019, KDH performed 2 040 orthopaedic operations, of which 91.3% were urgent or emergencies. KDH had the most orthopaedic resources and the lowest referral ratio (0.18) compared with other DHs (0.92 - 1.35). In Khayelitsha, 2 402 acute orthopaedic cases presented to community health clinics. Trauma (86.1%) was the most common mechanism of injury for acute orthopaedic referrals. Of clinic cases, 2 229 (92.8%) were referred to KDH and 173 (7.2%) directly to the tertiary hospital. The most common reason for direct tertiary referral was condition related (n=157; 90.8%). CONCLUSION: This study outlines a successful example of a decentralised orthopaedic surgical service that increased EESC accessibility and alleviated the high burden of tertiary referrals compared with other DHs with fewer resources. Further research on the barriers to scaling up orthopaedic DH capacity in SA is needed to improve equitable access to surgical care.
Asunto(s)
Ortopedia , Humanos , Sudáfrica/epidemiología , Estudios Retrospectivos , Derivación y Consulta , Centros de Atención TerciariaRESUMEN
BACKGROUND: There has been a steady increase in the use of electronic media and instant messaging among healthcare professionals, where it has been almost universally adopted in the workplace. The use of WhatsApp and its perceived benefits in healthcare have been extensively studied; however, there are concerns regarding the potential for ethical breaches in confidentiality through shared electronic patient information. OBJECTIVES: To identify the usage characteristics and incidence of shared patient information with WhatsApp use in a team of medical doctors in an unobserved and unregulated setting. METHODS: We conducted a retrospective cross-sectional content analysis of WhatsApp messages (n=3 340) among a team of 20 doctors in a South African district hospital over 6 months. All messages found within this time period were allocated unique identifiers. The text and image messages were thematically grouped into four categories, i.e. clinical care, resource allocation, social and administrative. Messages that contained patient-identifying information were included in the analysis. RESULTS: Of a total of 3 340 messages sent, 220 (6.6%) contained patient-identifying information. Of these, 109 (3.3%) contained non-anonymised patient information, while in 111 (3.3%) messages, the information was anonymised. The likelihood of sharing patient identifiers was proportionally much higher in shared images (odds ratio (OR) 5.1; 95% confidence interval (CI) 3.2 - 8.2; p<0.0001) compared with text messages, and in messages that related to clinical care (OR 9.3; 95% CI 2.2 - 38.8; p=0.0023) compared with those sent for resource allocation, and social or administrative purposes. CONCLUSIONS: Non-anonymised patient identifiers were found in 3.3% of messages, constituting the potential for breaching patient confidentiality. While WhatsApp groups have significant utility in co-ordinating aspects of clinical care, resource allocation, as well as social and administrative functions, the safe use of WhatsApp should be promoted to ensure that patient confidentiality is maintained.
Asunto(s)
Confidencialidad , Relaciones Interprofesionales/ética , Grupo de Atención al Paciente/organización & administración , Relaciones Profesional-Paciente/ética , Envío de Mensajes de Texto/estadística & datos numéricos , Estudios Transversales , Ética Médica , Hospitales de Distrito , Humanos , Estudios Retrospectivos , SudáfricaRESUMEN
Acquired haemophilia A is a rare coagulation disorder, which can lead to life-threatening haemorrhages if not identified and treated promptly. It is characterised by the presence of autoantibodies (inhibitors) to factor VIII. Acquired haemophilia A associated with HIV is a rare but well described phenomenon with limited directions to its management. We comparatively describe four patients - two with HIV and two without - that presented with unusual bleeding episodes with a prolonged activated partial thromboplastin time secondary to factor VIII inhibitors. An empiric observation is that the patients with acquired haemophilia A associated with HIV had higher antibody titres at presentation, that required more prolonged immunosuppressive therapy to induce remission.
Asunto(s)
Autoanticuerpos/sangre , Infecciones por VIH/inmunología , VIH/inmunología , Hemofilia A/tratamiento farmacológico , Hemofilia A/virología , Adulto , Anciano de 80 o más Años , Femenino , Infecciones por VIH/sangre , Infecciones por VIH/virología , Hemofilia A/inmunología , Humanos , Inmunosupresores/uso terapéutico , Quimioterapia de Inducción , Masculino , Persona de Mediana Edad , Tiempo de Tromboplastina Parcial , SudáfricaRESUMEN
Background. It is well established that South Africa (SA) suffers an immense burden of violence and injuries. The responsibility of providing care for these injuries falls mainly on public health services, resulting in overloading of the health system. Prior to a recent intervention, the large burden had been exacerbated by limitations in the traditional referral system that highlighted the need for a better referral system. Vula's smartphone app was introduced at Tygerberg Hospital in August 2016. This study evaluated the uptake, response times and outcomes using this app.Objectives. The main objectives of the study were to describe: (i) the number of referrals; (ii) referral response times; (iii) referring facilities; and (iv) referral outcomes. Secondary objectives were to: (i) evaluate whether the referral outcome pathway was appropriate; and (ii) assess professional conduct and evidence of upskilling.Methods. This retrospective, descriptive study investigated Vula app referrals to the Division of Orthopaedic Surgery at Tygerberg Hospital between 1 August 2016 and 31 March 2017. Vula was advertised to key facilities in the hospital's referral network. All referrals to the division during the study period were systematically included in the analysis of operational outcomes, although some were excluded from the subsequent referral outcome analysis. Operational outcomes included the number of referrals, referring facilities and referral response times. Referral outcome analysis included the clinical diagnosis, referral pathway, whether the referral was used for upskilling and whether it was conducted in a professional manner.Results. A total of 2 275 referrals from 39 different facilities were received during the study period from 238 individual users; 50% of referrals received a response within 11 minutes, while a small percentage received no response. Clinical and demographic characteristics of 1 985 patients included in the referral outcome analysis indicated that the majority of trauma and emergency referrals involved males, with closed fractures being the most frequent clinical presentation. Although the most common referral outcome was immediate transfer, one-third of the patients were treated at the referring hospital with advice only.Conclusions. The large volume of orthopaedic referrals received through the Vula app suggests that Vula represents a successful alternative to traditional referral methods. Referrals managed by advice only could suggest that Vula facilitates some relief for the overburdened trauma services. Future research could further explore Vula's role in strengthening the public health system, including interventions for high-volume referral areas and upskilling of referring health workers
Asunto(s)
Derivación y Consulta , Teléfono Inteligente , Sudáfrica , Telemedicina , Heridas y LesionesRESUMEN
The aim of this retrospective review was to assess the overall burden and trend in spinal tuberculosis (TB) at tertiary hospitals in the Western Cape Province of South Africa. All spinal TB cases seen at the province's three tertiary hospitals between 2012 and 2015 were identified and clinical records of each case assessed. Cases were subsequently classified as bacteriologically confirmed or clinically diagnosed and reported with accompanying clinical and demographic information. Odds ratios (OR) for severe spinal disease and corrective surgery in child vs. adult cases were calculated. A total of 393 cases were identified (319 adults, 74 children), of which 283 (72%) were bacteriologically confirmed. Adult cases decreased year-on-year (P = 0.04), however there was no clear trend in child cases. Kyphosis was present in 60/74 (81%) children and 243/315 (77%) adults with available imaging. Corrective spinal surgery was performed in 35/74 (47%) children and 80/319 (25%) adults (OR 2.7, 95% confidence interval 1.6-4.5, P = 0.0003). These findings suggest that Western Cape tertiary hospitals have experienced a substantial burden of spinal TB cases in recent years with a high proportion of severe presentation, particularly among children. Spinal TB remains a public health concern with increased vigilance required for earlier diagnosis, especially of child cases.
Asunto(s)
Costo de Enfermedad , Cifosis/epidemiología , Tuberculosis de la Columna Vertebral/epidemiología , Adolescente , Adulto , Niño , Preescolar , Femenino , Humanos , Lactante , Cifosis/patología , Masculino , Persona de Mediana Edad , Prevalencia , Estudios Retrospectivos , Sudáfrica/epidemiología , Centros de Atención Terciaria , Tuberculosis de la Columna Vertebral/complicaciones , Tuberculosis de la Columna Vertebral/patología , Adulto JovenRESUMEN
BACKGROUND: Little is known about how basic soil properties respond to contrasting grazing intensities in the Karoo biome, South Africa. The aim of this study was to investigate impacts of long-term (>75 years) grazing at 1.18 heads ha(-1) (heavy; CGH), 0.78 heads ha(-1) (light; CGL), and exclosure on selected soil properties. Soil samples were collected to a depth of 60 cm from the long-term experimental site of Grootfontein Agricultural Development Institute, Eastern Cape. The samples were analyzed for C, N, bulk density and infiltration rate, among others. RESULTS: Generally, heavy and light grazing reduced soil N storage by 27.5% and 22.6%, respectively, compared with the exclosure. Animal exclusion improved water infiltration rate and C stocks significantly (P < 0.05), which was 0.128, 0.097, and 0.093 Mg ha(-1) yr(-1) for exclosure, CGL and CGH, respectively. Soil penetration resistance was higher for grazing treatments in the top 3-7 cm soil layer but for exclosure at the top 1 cm soil surface. CONCLUSION: Although livestock exclusion has the potential to improve C sequestration, a sufficient resting period for 1-2 years followed by three consecutive grazing years at light stocking rate would be ideal for sustainable livestock production in this arid region of South Africa.
Asunto(s)
Carbono/química , Ecosistema , Conducta Alimentaria , Ganado/fisiología , Suelo/química , Animales , Nitrógeno/química , Plantas/clasificación , Sudáfrica , Factores de TiempoAsunto(s)
Implantes Dentales de Diente Único/ética , Odontólogos/ética , Ética Odontológica , Adulto , Discusiones Bioéticas , Implantes Dentales de Diente Único/economía , Relaciones Dentista-Paciente/ética , Femenino , Costos de la Atención en Salud/ética , Humanos , Incisivo/lesiones , Consentimiento Informado/ética , Planificación de Atención al Paciente/economía , Planificación de Atención al Paciente/ética , Medición de Riesgo/ética , Resorción Radicular/terapia , Extracción Dental/éticaAsunto(s)
Ética Odontológica , Xenoinjertos/trasplante , Procedimientos Quirúrgicos Orales/ética , Religión y Medicina , Aloinjertos/trasplante , Sustitutos de Huesos/uso terapéutico , Trasplante Óseo , Toma de Decisiones/ética , Implantación Dental Endoósea , Odontólogos/ética , Femenino , Humanos , Consentimiento Informado/ética , Membranas Artificiales , Sudáfrica , Adulto JovenAsunto(s)
Atención Odontológica/ética , Ética Odontológica , Planificación de Atención al Paciente/ética , Toma de Decisiones , Atención Odontológica/economía , Honorarios Odontológicos , Financiación Personal , Costos de la Atención en Salud , Humanos , Consentimiento Informado/ética , Educación del Paciente como Asunto , Participación del Paciente , Autonomía Personal , SudáfricaRESUMEN
Methylation of DNA in eukaryotic cells, global as well as gene-specific, is affected by endogenous and endogenous factors. In this paper, it is reported that deviations in DNA methylation and expression of genes involved in DNA repair and the cell cycle are affected in 143B cultured cells containing an expression vector. Global DNA methylation analysis with cytosine-extension assay revealed a decreased global DNA methylation in the presence of the expression vector. Less promoter-specific methylation, as measured by bisulfite-MS PCR, was observed for MGMT and p16INK4a in vector-containing cells. Comet assay investigations revealed a negative effect on the DNA repair capacity of both BER and NER in Complex III compromised cells. This was reflected in the down-regulation of hOGG1 and ERCC1 expression. The results presented in this paper support the existence of a strong relationship between impaired mitochondrial function and deviations in DNA methylation and extend this relationship to impaired DNA repair.
Asunto(s)
Metilación de ADN , Reparación del ADN , Células Eucariotas/metabolismo , Línea Celular , Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Metilasas de Modificación del ADN/genética , Epigénesis Genética , Regulación de la Expresión Génica , Regiones Promotoras GenéticasRESUMEN
Scat analysis is one of the most frequently used methods to assess carnivoran diets and Global Positioning System (GPS) cluster methods are increasingly being used to locate feeding sites for large carnivorans. However, both methods have inherent biases that limit their use. GPS methods to locate kill sites are biased towards large carcasses, while scat analysis over-estimates the biomass consumed from smaller prey. We combined carcass observations and scats collected along known movement routes, assessed using GPS data from four African lion (Panthera leo) prides in the Kruger National Park, South Africa, to determine how a combination of these two datasets change diet estimates. As expected, using carcasses alone under-estimated the number of feeding events on small species, primarily impala (Aepyceros melampus) and warthog (Phacochoerus africanus), in our case by more than 50% and thus significantly under-estimated the biomass consumed per pride per day in comparison to when the diet was assessed using carcass observations alone. We show that an approach that supplements carcass observations with scats that enables the identification of potentially missed feeding events increases the estimates of food intake rates for large carnivorans, with possible ramifications for predator-prey interaction studies dealing with biomass intake rate.
RESUMEN
Although many people welcome the recent move by the United States to give its Food and Drug Administration (FDA) the authority to regulate the content of tobacco, some worry that such regulation constitutes unwarranted interference with the freedom of competent adult tobacco consumers. The concern for protecting the autonomy of individuals is valuable indeed, but given the highly addictive nature of tobacco products (and especially the nicotine in tobacco products), the continued use of tobacco by smokers cannot -without straining credulity-be said to be autonomous. This fact, combined with a proper construal of the FDA's role and an appreciation of the substantial morbidity and mortality associated with tobacco use, makes a strong case for content regulation.
RESUMEN
The Mkuze Game Reserve (MGR), in north-eastern KwaZulu-Natal Province, South Africa is an African swine fever virus (ASF) controlled area. In a survey conducted in 1978, ASF prevalence in warthogs and Ornithodoros ticks in MGR was determined to be 2% and 0.06%, respectively. These values, acknowledged as being unusually low compared to other East and southern African ASF-positive sylvatic-cycle host populations, have not been assessed since. The availability of a sensitive PCR-based virus detection method, developed specifically for the sylvatic tampan host, prompted a re-evaluation of ASF virus (ASFV) prevalence in MGR ticks. Of the 98 warthog burrows inspected for Ornithodoros presence, 59 (60.2%) were found to contain tampans and tick sampling was significantly male-biased. Whilst gender sampling-bias is not unusual, the 27% increase in infestation rate of warthog burrows since the 1978 survey is noteworthy as it anticipates a concomitant increase in ASFV prevalence, particularly in light of the high proportion (75%) of adult ticks sampled. However, despite DNA integrity being confirmed by internal control amplification of the host 16S gene, PCR screening failed to detect ASFV. These results suggest that ASFV has either disappeared from MGR or if present, is localized, occurring at exceptionally low levels. Further extensive surveys are required to establish the ASFV status of sylvatic hosts in this controlled area.
Asunto(s)
Virus de la Fiebre Porcina Africana/aislamiento & purificación , Fiebre Porcina Africana/epidemiología , Vectores Arácnidos/virología , Ornithodoros/virología , Infestaciones por Garrapatas/veterinaria , Fiebre Porcina Africana/virología , Virus de la Fiebre Porcina Africana/clasificación , Virus de la Fiebre Porcina Africana/genética , Animales , ADN Viral/análisis , Femenino , Genotipo , Masculino , Filogenia , Reacción en Cadena de la Polimerasa/veterinaria , Factores Sexuales , Sudáfrica/epidemiología , Porcinos , Infestaciones por Garrapatas/epidemiologíaRESUMEN
We measured browsing-induced responses of Acacia trees to investigate "browsing lawns" as an analogy to grazing lawns in a semiarid eutrophic African savanna. During the two-year field study, we measured plant tolerance, resistance, and phenological traits, while comparing variation in leaf nitrogen and specific leaf area (SLA) across stands of Acacia nigrescens, Miller, that had experienced markedly different histories of attack from large herbivores. Trees in heavily browsed stands developed (1) tolerance traits such as high regrowth abilities in shoots and leaves, high annual branch growth rates, extensive tree branching and evidence of internal N translocation, and (2) resistance traits such as close thorn spacing. However, phenological "escape" responses were weak even in heavily browsed stands. Overall, browsing strongly affected plant morpho-functional traits and decreased both the number of trees carrying pods and the number of pods per tree in heavily browsed stands. Hence, there is experimental evidence that tolerance and resistance traits may occur simultaneously at heavily browsed sites, but this comes at the expense of reproductive success. Such tolerance and resistance traits may coexist if browsers trigger and maintain a positive feedback loop in which trees are continually investing in regrowth (tolerance), and if the plant's physical defenses (resistance) are not nutritionally costly and are long-lived. Our results confirm that chronic browsing by ungulates can maintain A. nigrescens trees in a hedged state that is analogous to a grazing lawn. Further research is needed to fully understand the long-term effects of chronic browsing on reproduction within such tree populations, as well as the overall effects on nutrient cycling at the ecosystem level.
Asunto(s)
Acacia , Ecosistema , Mamíferos , Árboles , Acacia/crecimiento & desarrollo , Acacia/fisiología , Adaptación Fisiológica , Animales , Hojas de la Planta/crecimiento & desarrollo , Brotes de la Planta/crecimiento & desarrollo , Plantas Comestibles , SudáfricaRESUMEN
Counselling about antiretroviral therapy (ART) is thought important to prepare patients for treatment and enhance adherence. A workplace-based HIV care programme in South Africa instituted a three-step ART counselling protocol with guidelines prompting issues to be covered at each step. We carried out an early evaluation of ART counselling to determine whether patients understood key information about ART, and the perceptions that patients and health care professionals (HCP) had of the process. Among 40 patients (median time on ART 83 days), over 90% answered 6/7 HIV/ART knowledge-related questions correctly. 95% thought counselling sessions were good. 93% thought ongoing counselling was important. Recommendations included the need for continuing education about HIV/ART, being respectful, promoting HIV testing and addressing the issues of infected partners and stigma. 24 participating HCP identified additional training needs including counselling of family and friends, family planning, sexually transmitted infections and running support groups. 90% of HCP thought that counselling guidelines were helpful. The programme appears to be preparing patients well for ART. Counselling should be offered at every clinic visit. Counselling guidelines were a valuable tool and may be useful elsewhere. The evaluation helped to assess the quality of the programme and to suggest areas for improvement.
Asunto(s)
Terapia Antirretroviral Altamente Activa , Actitud del Personal de Salud , Consejo/normas , Infecciones por VIH/psicología , Educación del Paciente como Asunto/métodos , Adulto , Consejo/organización & administración , Femenino , Guías como Asunto , Infecciones por VIH/tratamiento farmacológico , Humanos , Masculino , Persona de Mediana Edad , Aceptación de la Atención de Salud , Evaluación de Programas y Proyectos de Salud , Sudáfrica , Encuestas y Cuestionarios , Lugar de TrabajoRESUMEN
We compared the diurnal activity budgets of four syntopic species of African browsing ruminant that differ widely in body size. These were concurrently studied through all phases of the seasonal cycle, in the same area, using the same methods. We tested five predictions from the literature on how body size is expected to influence the behaviour of tropical ungulates: the smallest members of the browsing ruminant guild exhibit (1) the lowest allocation of diurnal time to activity; (2) the greatest hour-to-hour variation in activity and resting time; (3) the greatest reduction in activity time during the hottest days; (4) the least change between wet and the dry seasons in the ratio of feeding: ruminating time; and (5) the greatest time budget allocation to vigilance. Prediction 1 was supported in that the smaller species spent less time being active during the day. Prediction 2 was also supported in that the smaller species were more variable in their relative allocations of time to activity and resting through successive hours of the day. Contrary to Prediction 3, however, the greatest reduction in activity with increasing temperature was found for the largest guild member. The smaller species can achieve their daily food intake requirements by feeding at night and in the cool hours of the day, while the larger species have to feed during all hours of the day and are thus more susceptible to thermoregulatory constraints on foraging. Prediction 4 was partially upheld in that the largest species (giraffe) displayed the widest variation in feeding: ruminating time through the seasonal cycle. Prediction 5 was not supported, indicating that multiple factors interact with body size in determining vigilance behaviour.