ABSTRACT
Sugarcane is an economically important crop plant across the globe as it is the primary source of sugar and biofuel. Its growth and development are greatly influenced by water availability; therefore, in periods of water scarcity, yields are severely compromised. Small Ubiquitin-Like Modifier (SUMO) proteases play an important role in stress responses by regulating the SUMO-related post-translational modification of proteins. In an attempt to enhance drought tolerance in sugarcane, this crop was genetically transformed with a cysteine protease (OVERLY TOLERANT TO SALT-1; OTS1) from Arabidopsis thaliana using particle bombardment. Transgenic plants were analysed in terms of photosynthetic capacity, oxidative damage, antioxidant accumulation and the SUMO-enrich protein profile was assessed. Sugarcane transformed with the AtOTS1 gene displayed enhanced drought tolerance and delayed leaf senescence under water deficit compared to the untransformed wild type (WT). The AtOTS1 transgenic plants maintained a high relative moisture content and higher photosynthesis rate when compared to the WT. In addition, when the transgene was expressed at high levels, the transformed plants were able to maintain higher stomatal conductance and chlorophyl content under moderate stress compared to the WT. Under severe water deficit stress, the transgenic plants accumulated less malondialdehyde and maintained membrane integrity. SUMOylation of total protein and protease activity was lower in the AtOTS1 transformed plants compared to the WT, with several SUMO-enriched proteins exclusively expressed in the transgenics when exposed to water deficit stress. SUMOylation of proteins likely influenced various mechanisms contributing to enhanced drought tolerance in sugarcane.
Subject(s)
Arabidopsis , Saccharum , Saccharum/genetics , Peptide Hydrolases/metabolism , Ubiquitin/metabolism , Drought Resistance , Plants, Genetically Modified/metabolism , Arabidopsis/metabolism , Endopeptidases/metabolism , Ubiquitins/genetics , Ubiquitins/metabolism , Water/metabolism , Droughts , Plant Proteins/genetics , Plant Proteins/metabolism , Gene Expression Regulation, Plant , Stress, Physiological/geneticsABSTRACT
The ordinary (superconductor-insulator-superconductor) Josephson junction cannot exhibit chaos in the absence of an external ac drive, whereas in the superconductor-ferromagnet-superconductor Josephson junction, known as the φ_{0} junction, the magnetic layer effectively provides two extra degrees of freedom that can facilitate chaotic dynamics in the resulting four-dimensional autonomous system. In this work, we use the Landau-Lifshitz-Gilbert model for the magnetic moment of the ferromagnetic weak link, while the Josephson junction is described by the resistively capacitively shunted-junction model. We study the chaotic dynamics of the system for parameters surrounding the ferromagnetic resonance region, i.e., for which the Josephson frequency is reasonably close to the ferromagnetic frequency. We show that, due to the conservation of magnetic moment magnitude, two of the numerically computed full spectrum Lyapunov characteristic exponents are trivially zero. One-parameter bifurcation diagrams are used to investigate various transitions that occur between quasiperiodic, chaotic, and regular regions as the dc-bias current through the junction, I, is varied. We also compute two-dimensional bifurcation diagrams, which are similar to traditional isospike diagrams, to display the different periodicities and synchronization properties in the I-G parameter space, where G is the ratio between the Josephson energy and the magnetic anisotropy energy. We find that as I is reduced the onset of chaos occurs shortly before the transition to the superconducting state. This onset of chaos is signaled by a rapid rise in supercurrent (I_{S}â¶I) which corresponds, dynamically, to increasing anharmonicity in phase rotations of the junction.
ABSTRACT
Wastewater stabilization ponds (WSPs) rely on the metabolic activities of the inhabiting microbiota to treat wastewater. A selected consortium of Chlorella vulgaris and Chlorella protothecoides were used to manipulate the natural resident microalgae assemblage to improve the treatment performance of a domestic wastewater pond treatment system in a coastal region. Since information is lacking about the resulting influence on the composition or succession of the phytoplankton or associated microbiota assemblage, the current study aimed to determine how dosing with the microalgae C. vulgaris and C. protothecoides change the efficiency of wastewater effluent treatment, as well as the composition and succession of the natural occurring phytoplankton and microbial assemblage throughout WSP system. After a year of specific microalgae inoculations, the effluent in part complied with the standards set by the Department of Water Affairs and Forestry (DWAF) and the USA, Environmental Protection Agency (EPA). The cyanobacteria Microcystis aeruginosa dominated the sixth (75%) and seventh pond (97%) before the inoculation with C. vulgaris and C. protothecoide commenced. After 12 inoculation events C. vulgaris and C. protothecoides were dominant in ponds three to seven while the dominant microbial groups were Bacteroidetes, Cyanobacteria, Firmicutes, Planctomycetes, Proteobacteria, Spirochaetes, Synergistetes and Verrucomicrobia. After the microalgae treatment, the WSP effluent were more compliant regarding to the set guidelines for effluent than prior to microalgae treatment. Based on the ability of the C. vulgaris and C. protothecoides to improve the effluent water quality, it was evident that the consortium of microalgae can be use improve domestic wastewater effluent in rural nutrient sensitive catchments. Supplementary Information: The online version contains supplementary material available at 10.1007/s40201-022-00840-z.
ABSTRACT
Irregular easy axis reorientation features are observed in numerical simulations of the nanomagnet coupled to the Josephson junction. We study magnetization bifurcations and chaos that appear in this system due to the interplay of superconductivity and magnetism. The bifurcation structure of magnetization under the variation of Josephson to magnetic energy ratio as a control parameter demonstrates several precessional motions that are related to chaotic behavior and orbits with different periodicities in the ferromagnetic resonance region. The effect of an external periodic signal on the bifurcation structure is also investigated. The results demonstrate high-frequency modes of a periodic motion and a chaotic response near resonance. Far from the ferromagnetic resonance, we observe a quasiperiodic behavior. The obtained results explain the irregular reorientation of the easy axis and the transitions between different types of motion.
ABSTRACT
The union of the Kuramoto-Sakaguchi model and the Hebb dynamics reproduces the Lisman switch through a bistability in synchronized states. Here, we show that, within certain ranges of the frustration parameter, the chimera pattern can emerge, causing a different, time-evolving, distribution in the Hebbian synaptic strengths. We study the stability range of the chimera as a function of the frustration (phase-lag) parameter. Depending on the range of the frustration, two different types of chimeras can appear spontaneously, i.e., from randomized initial conditions. In the first type, the oscillators in the coherent region rotate, on average, slower than those in the incoherent region; while in the second type, the average rotational frequencies of the two regions are reversed, i.e., the coherent region runs, on average, faster than the incoherent region. We also show that non-stationary behavior at finite N can be controlled by adjusting the natural frequency of a single pacemaker oscillator. By slowly cycling the frequency of the pacemaker, we observe hysteresis in the system. Finally, we discuss how we can have a model for learning and memory.
ABSTRACT
SUMMARY: Gestational gigantomastia is rare and characterised by rapid and disproportionate enlargement of the breast during pregnancy. It often requires surgical removal of more than 1500 g of breast tissue. Of the 50 case reports published worldwide, not one was in South African literature. This unusual case report is of a female presenting with gigantomastia at five weeks gestational age. The patient was multiparous and decided to terminate the pregnancy due to the physical and emotional effects of the large, pendulous breasts. Management included breast reduction and free nipple grafting in a staged approach. The complications are briefly outlined. Despite rare presentation, patient satisfaction was achieved.
Subject(s)
Mammaplasty , Breast/abnormalities , Female , Humans , Hypertrophy/surgery , Mammaplasty/adverse effects , Nipples/surgery , PregnancyABSTRACT
Fluctuation theorems allow one to obtain equilibrium information from nonequilibrium experiments. The probability distribution function of the relevant magnitude measured along the irreversible nonequilibrium trajectories is an essential ingredient of fluctuation theorems. In small systems, where fluctuations can be larger than average values, probability distribution functions often deviate from being Gaussian, showing long tails, mostly exponential, and usually strongly asymmetric. Recently, the probability distribution function of the van Hove correlation function of the relevant magnitude was calculated, instead of that of the magnitude itself. The resulting probability distribution function is highly symmetric, obscuring the application of fluctuation theorems. Here, the discussion is illustrated with the help of results for the heat exchanged during plastic deformation of aluminum nanowires, obtained from molecular dynamics calculations. We find that the probability distribution function for the heat exchanged is centrally Gaussian, with asymmetric exponential tails further out. By calculating the symmetry function we show that this distribution is consistent with fluctuation theorems relating the differences between two equilibrium states to an infinite number of nonequilibrium paths connecting those two states.
ABSTRACT
The newer beta-lactam-inhibitor combination (BLIC) antibiotics are available in South Africa (SA) for the treatment of carbapenem-resistant Enterobacterales infections. We describe the successful use of ceftazidime-avibactam (CA) for the treatment of a child with persistent carbapenem-resistant Serratia marcescens bacteraemia, and the challenges faced using this lifesaving antibiotic, including access to susceptibility testing, procurement process, cost and complexity of deciding when, how and for how long to use it. Furthermore, the burden of carbapenem resistance is increasing in SA, and inappropriate use of CA and other newer BLIC antibiotics, such as ceftolozane-tazobactam, will inevitably endanger their longevity. A careful balance must be struck between removing unnecessary obstacles and delays in initiating these antibiotics for life-threatening infections, and additional antimicrobial stewardship-guided interventions aimed at preserving their therapeutic use.
Subject(s)
Azabicyclo Compounds/pharmacology , Ceftazidime/pharmacology , Serratia Infections/drug therapy , Serratia marcescens/drug effects , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Antimicrobial Stewardship/methods , Antimicrobial Stewardship/statistics & numerical data , Azabicyclo Compounds/therapeutic use , Burns/drug therapy , Burns/physiopathology , Carbapenems/pharmacology , Carbapenems/therapeutic use , Ceftazidime/therapeutic use , Drug Combinations , Female , Humans , Infant , Serratia Infections/physiopathology , Serratia marcescens/pathogenicity , South AfricaABSTRACT
The study presents an evaluation of nitrogen removal efficiency of a pilot-scale rhizofiltration system in Pretoria, South Africa. The rhizofiltration system was divided into two sections, one side planted with common reeds (Phragmites australis) and the other side was without plants kept as a control. The objective of the study was to evaluate the influence of seasonal temperature on the removal of nitrogen species from the simulated urban runoff using the rhizofiltration system. The final effluent from the filter was collected bimonthly at different sampling points for 10 months after an application time of 5 min and 25 min. Duplicate samples were taken to determine the concentrations of TKN (Total Kjeldahl nitrogen), ammonium, nitrate and chemical oxygen demand (COD) for the raw influent and final effluent from the rhizofiltration system. Temperature and pH were determined on-site. During the monitoring period, there was no significant difference in the inflow concentration of ammonium in colder and warmer months for both planted and control sides. Furthermore, the composition of the feed medium to the rhizofilter was kept the same in both cold and warm season and for both planted and control sides. The removal of ammonium in colder and warmer months was not significant in both systems. At an average temperature increase of 5.2 °C in the warmer months, the ammonium removal efficiency in the planted side increased by 7.5%, while for the control side the removal efficiency increased by 2.4%. The difference in removal was not significant between the averages of effluent ammonium after an application time of 25 min in colder versus warmer months for the planted and control sides of the system. Furthermore, an increased nitrification rate was more evident in the planted than in the control side, which was subsequently denitrified. It was observed that 60.4% of nitrate concentration was potentially removed in the planted side whereas 45.4% was potentially denitrified in the control side. These results suggest positive correlation between nitrate concentration and the potential for denitrification. The nitrate removal efficiency dropped to 32.2% for the planted site and to 26.1% for the control system in colder months. Temperature had an effect on nitrogen removal, since nitrogen removal efficiency decreased in colder months. Complete nitrogen removal could not be achieved under the operating conditions.
Subject(s)
Denitrification , Nitrogen/analysis , Nitrification , Seasons , South Africa , TemperatureABSTRACT
Background. Medical students are at risk of burnout owing to various challenges.Objectives. To investigate burnout and associated factors among undergraduate students at a South African medical school.Methods. In this cross-sectional study, findings of the Copenhagen Burnout Inventory (CBI), demographic data and information related to resilience were collected by means of an anonymous self-administered questionnaire. Associations between burnout subscales and various factors were determined.Results. Five-hundred students (preclinical, n=270; clinical, n=230) completed the questionnaire. CBI mean scores for preclinical and clinical students were 17.9 and 17.4 (personal), 22.3 and 21.9 (work related) and 24.8 (patient related; clinical students only), respectively. High scores on the subscale reflect low levels of burnout in related areas. Male students and students with high self-reported resilience and low stress had significantly lower burnout levels. White preclinical students had lower levels of personal and work-related burnout, and black clinical students had less patient-related burnout.High mean scores in all three burnout subscales indicated low burnout levels among students. Academic and personal stress, as well as perceived poor support from institutional structures, were associated with significantly higher personal and work-related burnout, but not patient-related burnout in clinical students
Subject(s)
Burnout, Psychological , Equipment and Supplies , Resilience, Psychological , Students, MedicalABSTRACT
The Galactic Centre contains a supermassive black hole with a mass of four million Suns1 within an environment that differs markedly from that of the Galactic disk. Although the black hole is essentially quiescent in the broader context of active galactic nuclei, X-ray observations have provided evidence for energetic outbursts from its surroundings2. Also, although the levels of star formation in the Galactic Centre have been approximately constant over the past few hundred million years, there is evidence of increased short-duration bursts3, strongly influenced by the interaction of the black hole with the enhanced gas density present within the ring-like central molecular zone4 at Galactic longitude |l| < 0.7 degrees and latitude |b| < 0.2 degrees. The inner 200-parsec region is characterized by large amounts of warm molecular gas5, a high cosmic-ray ionization rate6, unusual gas chemistry, enhanced synchrotron emission7,8, and a multitude of radio-emitting magnetized filaments9, the origin of which has not been established. Here we report radio imaging that reveals a bipolar bubble structure, with an overall span of 1 degree by 3 degrees (140 parsecs × 430 parsecs), extending above and below the Galactic plane and apparently associated with the Galactic Centre. The structure is edge-brightened and bounded, with symmetry implying creation by an energetic event in the Galactic Centre. We estimate the age of the bubbles to be a few million years, with a total energy of 7 × 1052 ergs. We postulate that the progenitor event was a major contributor to the increased cosmic-ray density in the Galactic Centre, and is in turn the principal source of the relativistic particles required to power the synchrotron emission of the radio filaments within and in the vicinity of the bubble cavities.
ABSTRACT
The effects of inertial terms on the dynamics of the dc+ac driven Frenkel-Kontorova model were examined. As the mass of particles was varied, the response of the system to the driving forces and appearance of the Shapiro steps were analyzed in detail. Unlike in the overdamped case, the increase of mass led to the appearance of the whole series of subharmonic steps in the staircase of the average velocity as a function of average driving force in any commensurate structure. At certain values of parameters, the subharmonic steps became separated by chaotic windows while the whole structure retained scaling similar to the original staircase. The mass of the particles also determined their sensitivity to the forces governing their dynamics. Depending on their mass, they were found to exhibit three types of dynamics, from dynamical mode-locking with chaotic windows, through to a typical dc response, to essentially a free-particle response. Examination of this dynamics in both the upforce and downforce directions showed that the system may not only exhibit hysteresis, but also that large Shapiro steps may appear in the downforce direction, even in cases for which no dynamical mode-locking occurred in the upforce direction.
ABSTRACT
Spodoptera frugiperda (J.E. Smith) is an invasive pest species that threatens maize production by small holder farmers in Africa. Bt maize that express Cry proteins have been used effectively for control of this pest in the United States, Canada, and several countries in South America. Spodoptera frugiperda has evolved resistance to Cry1F Bt maize in Puerto Rico, Brazil and United States, and Cry1Ab Bt maize in Brazil. This study provides the first data on the efficacy of Bt maize for the control of S. frugiperda in Africa. Susceptibility levels of nine S. frugiperda populations were evaluated between January 2018 and May 2018, including a laboratory reared reference population. Larval feeding bioassays were conducted in which plant tissue of maize expressing Cry1Ab (single-toxin event - designated Bt1) or Cry1A.105 + Cry2Ab2 (pyramid-toxin event - designated Bt2), were fed to larvae. Survival and different life history parameters were recorded. Results indicate moderate survival on Bt1 maize, which supports field observations of commercial level control provided by this event. Very high levels of S. frugiperda larval mortality occurred on Bt2 maize (<1% survival). The moderate susceptibility of S. frugiperda to Cry1Ab could be ascribed to the latter being a low-dose event for this pest, as well as the fact that the individuals which initially arrived on the continent may have carried alleles with resistance to this protein. Moderate overall survivorship (4-35%) of S. frugiperda on Cry1Ab maize in South Africa reflects the possible presence of alleles resistant to this toxin, indicating the importance of future resistance monitoring.
Subject(s)
Hemolysin Proteins , Zea mays , Animals , Bacterial Proteins , Brazil , Canada , Endotoxins , Insecticide Resistance , Larva , Plants, Genetically Modified , Puerto Rico , South Africa , SpodopteraABSTRACT
The success and long term effectiveness of extensive and expensive engineering solutions to restore streams impacted by Acid Mine Drainage (AMD) is rarely tested. Concentrations of pollutants were measured in water along a longitudinal gradient from a stretch of the Tweelopie stream, South Africa, that receives pH-treated acid mine drainage (AMD) from an abandoned gold mine. The biotoxic effects of treated AMD were determined through macroinvertebrate biotic indices (SASS5) and a battery of toxicity bioassays. These included the L. sativa, A. cepa, D. magna toxicity and Ames mutagenicity tests, as well as an in vitro human liver cancer cell line HepG2. Even though the Tweelopie stream was moderately to severely degraded by multiple anthropogenic stressors, the impact of the treated AMD was masked by the improvement in the system downstream after mixing with the domestic wastewater effluent receiving stream, and subsequent further dilution as a result of the karst springs downstream. The general improvement of the system downstream was clearly shown by the decrease in the ecotoxicity and mutagenicity in relation to the in-stream macroinvertebrates. PCA multivariate analysis successfully displayed associations between the different environmental variables and the decrease in toxicity and subsequent ecosystem improvement downstream. This study indicated that environmental management of AMD remediation should consider long term assessment strategies, including multiple factors, to promote biological ecosystem recovery.
Subject(s)
Ecosystem , Water Pollutants, Chemical , Biological Assay , Environmental Monitoring , Invertebrates , Mining , South AfricaABSTRACT
BACKGROUND: Diaphragmatic and hiatus hernias can cause mild chronic symptoms or have an acute presentation with gastric volvulus and obstruction. Elective or emergency surgery is indicated in symptomatic patients and nowadays is generally performed laparoscopically. METHODS: We report four different types of hernias: a giant hiatus hernia following a gastric pull-up for recurrent congenital diaphragmatic hernia; a Bochdalek hernia in a pregnant young woman; concomitant hiatus and Morgagni hernias; and a giant hiatus hernia occupying the right chest. All were approached laparoscopically, either electively or as an emergency. RESULTS: Surgery led to a resolution of symptoms in all the cases. We had no any intraoperative complications. Two patients developed minor postoperative complications (chest infection). No recurrences were found during a mean follow-up of 18 months. CONCLUSIONS: Transabdominal laparoscopic approach is a safe and feasible approach to all cases of symptomatic hiatus and diaphragmatic hernia.
Subject(s)
Hernia, Hiatal/surgery , Hernias, Diaphragmatic, Congenital/complications , Herniorrhaphy/methods , Laparoscopy/methods , Pregnancy Complications/surgery , Adult , Aged , Diaphragm/surgery , Female , Hernia, Hiatal/etiology , Herniorrhaphy/adverse effects , Humans , Laparoscopy/adverse effects , Middle Aged , Postoperative Complications/epidemiology , Postoperative Complications/etiology , Pregnancy , Pregnancy Complications/etiology , Recurrence , Treatment Outcome , Young AdultABSTRACT
BACKGROUND: The incidence of learner teenage pregnancies can be reduced, provided that the major stakeholders, which include the Department of Education and the Department of Health, combine to address this issue. Despite the implementation of Life Orientation as a school subject, which focuses on sexual behaviour, health, decision-making, pregnancy risk, sexually transmitted infections and HIV and AIDS, the prevalence of learner teenage pregnancies at secondary schools remains alarmingly high. AIM: The purpose of this study was to explore and describe teachers' experiences of learner teenage pregnancies in secondary schools in a province in South Africa. SETTING: Secondary schools in KwaZulu-Natal. METHOD: A qualitative approach with exploratory, descriptive and contextual strategies was used in this research. Semi-structured interviews were conducted with teachers who had been selected through purposive sampling. Tesch's steps of systematic open coding were used to analyse all of the interviews. RESULTS: The results that emerged during the data analysis indicate that firstly, teachers' experiences of having pregnant learners in their classrooms are negative as these learners are frequently absent from school, perform badly and drop out of school. Secondly, teachers' experiences related to unexpected deliveries are coloured by their lack of the necessary skills and competencies to deal and their resultant insecurity. Thirdly, the teachers feel that they do not receive the assistance they need to deal with teenage pregnancies as well as unexpected deliveries. CONCLUSIONS: Collaboration between and continuous support from the Department of Health and the Department of Education are crucial if teenage pregnancies at secondary schools are to be handled with greater success. Support from health care personnel should include guidance on contraception and health campaigns should target both the teachers and secondary school learners. Furthermore, coping strategies for the teachers should form part of the preservice curriculum of teachers.
ABSTRACT
Background: The incidence of learner teenage pregnancies can be reduced, provided that the major stakeholders, which include the Department of Education and the Department of Health, combine to address this issue. Despite the implementation of Life Orientation as a school subject, which focuses on sexual behaviour, health, decision-making, pregnancy risk, sexually transmitted infections and HIV and AIDS, the prevalence of learner teenage pregnancies at secondary schools remains alarmingly high.Aim: The purpose of this study was to explore and describe teachers' experiences of learner teenage pregnancies in secondary schools in a province in South Africa.Setting: Secondary schools in KwaZulu-Natal.Method: A qualitative approach with exploratory, descriptive and contextual strategies was used in this research. Semi-structured interviews were conducted with teachers who had been selected through purposive sampling. Tesch's steps of systematic open coding were used to analyse all of the interviews.Results: The results that emerged during the data analysis indicate that firstly, teachers' experiences of having pregnant learners in their classrooms are negative as these learners are frequently absent from school, perform badly and drop out of school. Secondly, teachers' experiences related to unexpected deliveries are coloured by their lack of the necessary skills and competencies to deal and their resultant insecurity. Thirdly, the teachers feel that they do not receive the assistance they need to deal with teenage pregnancies as well as unexpected deliveries.Conclusions: Collaboration between and continuous support from the Department of Health and the Department of Education are crucial if teenage pregnancies at secondary schools are to be handled with greater success. Support from health care personnel should include guidance on contraception and health campaigns should target both the teachers and secondary school learners. Furthermore, coping strategies for the teachers should form part of the preservice curriculum of teachers
Subject(s)
Delivery, Obstetric , Pregnancy in Adolescence/epidemiology , Pregnancy in Adolescence/statistics & numerical data , Schools , South AfricaABSTRACT
Background: The incidence of learner teenage pregnancies can be reduced, provided that the major stakeholders, which include the Department of Education and the Department of Health, combine to address this issue. Despite the implementation of Life Orientation as a school subject, which focuses on sexual behaviour, health, decision-making, pregnancy risk,sexually transmitted infections and HIV and AIDS, the prevalence of learner teenage pregnancies at secondary schools remains alarmingly high. Aim: The purpose of this study was to explore and describe teachers' experiences of learner teenage pregnancies in secondary schools in a province in South Africa. Setting: Secondary schools in KwaZulu-Natal. Method: A qualitative approach with exploratory, descriptive and contextual strategies was used in this research. Semi-structured interviews were conducted with teachers who had been selected through purposive sampling. Tesch's steps of systematic open coding were used to analyse all of the interviews. Results: The results that emerged during the data analysis indicate that firstly, teachers' experiences of having pregnant learners in their classrooms are negative as these learners are frequently absent from school, perform badly and drop out of school. Secondly, teachers' experiences related to unexpected deliveries are coloured by their lack of the necessary skills and competencies to deal and their resultant insecurity. Thirdly, the teachers feel that they do not receive the assistance they need to deal with teenage pregnancies as well as unexpected deliveries. Conclusions: Collaboration between and continuous support from the Department of Health and the Department of Education are crucial if teenage pregnancies at secondary schools are to be handled with greater success. Support from health care personnel should include guidance on contraception and health campaigns should target both the teachers and secondary school learners. Furthermore, coping strategies for the teachers should form part of the preservice curriculum of teachers
Subject(s)
Pregnancy in Adolescence , School Teachers , Schools , South AfricaABSTRACT
Long gap oesophageal atresia presents a surgical challenge as there is insufficient length of the oesophagus to restore continuity. Oesophageal replacement is generally achieved using a conduit, taken from the stomach, jejunum or colon. Preferences of approach vary between and within surgical centres. Specific to colonic interposition, the continued growth and dilation of the interposed segment may lead to redundancy. Revision surgery in these cases is challenging and has been sparsely described in adult patients. We present two patients who had colonic interposition for long gap oesophageal atresia in infancy and who then underwent successful revision surgery in their fifth decade.
Subject(s)
Anastomosis, Surgical/adverse effects , Colon/surgery , Digestive System Surgical Procedures/methods , Esophageal Atresia/surgery , Reoperation/methods , Digestive System Surgical Procedures/adverse effects , Dilatation , Female , Humans , Middle Aged , Postoperative Complications/surgery , Tomography, X-Ray ComputedABSTRACT
Obligate scavengers such as vultures provide critical ecosystem services and their populations have undergone severe declines in Asia and Africa. Intentional poisoning is a major threat to vultures in Africa, yet the impact on vulture populations of where poisoned carcasses are positioned is not known. We used re-sightings of 183 African white-backed vultures captured and tagged in two regions of South Africa, some 200 km apart, to estimate spatial differences in relative survival rates across life stages. Juvenile survival rates were similar in the two regions, whilst subadult and adult survival rates differed significantly. Using agent-based modelling, we show that this pattern of relative survival rates is consistent between regions that differ in intensity of poisoning, despite the proximity of the two regions. This may have important consequences for vulture conservation and the targeting of conservation efforts, particularly with regard to the efficacy of "vulture safe zones" around vulture breeding populations.