Disseminated mucormycosis and necrotizing fasciitis in immune-compromised patients: Two case reports

We present two case reports of disseminated mucormycosis and necrotizing fasciitis in an immunecompromised patient. First, a 3-month-old with untreated HIV infection presented in septic shock with abdominal wall-necrotizing fasciitis. Laparotomy  revealed extensive abdominal wall necrosis, bowel, liver, kidney and subsequent retroperitoneal, posterior diaphragm and inferior vena cava involvement. Second, a  3-year-old on chemotherapy for Burkitt’s lymphoma presented with pancytopenia, sepsis, abdominal wall-necrotizing fasciitis and left lower limb ischaemia. At surgery, there was necrosis of the abdominal wall, the large bowel and the ureter and thrombosis of the iliac vessels. Histology in both cases showed necrosis with fungal invasion consistent with mucormycosis. Both patients suffered mortality. We discuss  mucormycosis and review the literature regarding mucormycosis in immune-compromised paediatric patients.Keywords: child, immune-compromised, mucormycosis, necrotizing fasciitis, paediatri

The evolving management of Burkitt's lymphoma at Red Cross Children's Hospital

No Abstract. South African Medical Journal Vol. 96(9) (Part 2) 2006: 950-95

The evolving management of Burkitt's lymphoma at Red CrossChildren's Hospital

Background. Treatment for Burkitt’s lymphoma at Red Cross Children’s Hospital has evolved from the use of aggressive surgery and less intensive chemotherapy to a conservative surgical approach with more intensive chemotherapy. Methods. The study was a retrospective folder review of patients diagnosed with Burkitt’s lymphoma at RCCH between 1984 and 2004. Results. Ninety-two children were treated for Burkitt’s lymphoma at RCCH between 1984 and 2004. There were 10 patients with group A or fully resected disease, 52 with group B or extensive localised disease, and 30 with dissemination to the bone marrow and/or central nervous system or group C disease. Protocol 1 (less intensive chemotherapy based on the COMP regimen) was used from 1984, with protocol 2 (more intensive chemotherapy based on the LMB regimen) introduced in 1988 for group C disease, 1991 for group B disease and 1996 for group A disease. Overall 5-year survival increased from 20% with protocol 1 to 66% with protocol 2 for group C disease, and from 76.5% with protocol 1 to 88.2% with protocol 2 for group B disease. There were more admissions for neutropenic fever in patients on protocol 2 and more episodes of mucositis, and these patients required more red cell and platelet transfusions. With a more conservative surgical approach, biopsy largely replaced attempts to partially resect the tumour at primary surgery, and there was a consequent decline in surgical complications. Conclusions. Intensive chemotherapy with protocol 2 has resulted in improved survival for group C and group B patients, but with more morbidity. Protocol 1, which is less intensive with less morbidity, remains a viable strategy for group A and group B disease in resource-poor settings

Comparison in the incidence of anorectal malformations between a first- and third-world referral center

PURPOSE : Aim of study was to evaluate the differences in incidence and presentation of anorectal malformations (ARMs) between selected Pediatric Surgery Divisions in the Republic of South Africa (ZAR) and Italy. METHODS : A retrospective cohort study involved analysis of clinical records of patients with ARM born between 2005 and 2012. Type of ARM, maternal age, birth weight, gestational age, presence of associated anomalies and delayed diagnosis were analyzed. RESULTS : 335 patients were included in this study. Of note, statistically significant differences between the African and European patient groups were observed in a male predominance in the ZAR patient population. In addition, female recto-perineal fistulas were diagnosed in significantly more Italian patients than in ZAR. Furthermore, a more advanced maternal age and a lower gestational age was noted in the European cohort with a minimal delay in initial diagnosis as opposed to the African counterpart. Both centers reported recto-perineal fistula as the most common malformation in male patients. CONCLUSION : With the exception of perineal fistulas in females, the incidence of specific subtypes of ARMs was similar in the two groups. This may be of importance when extrapolating European study conclusion to the South African setting.http://link.springer.com/journal/3832016-08-31hb201

Salvageability of renal function following renal revascularisation in children with Takayasu’s arteritis-induced renal artery stenosis

Background. Renal artery revascularisation procedures are usually carried out on children with renal artery stenosis from varied causes, including Takayasu’s arteritis. Reports on the outcome of such procedures in children usually refer to the improvement in blood pressure, with only minimal mention of effects on renal function.Objective. Salvageability of renal function in children who underwent renal revascularisation for Takayasu’s arteritis-induced renal artery stenosis (TARAS) was the focus of this study.Methods. We undertook a retrospective analysis of children aged ≤16 years with angiographically confirmed TARAS who underwent renal artery revascularisation procedures between 1990 and 2010. Outcomes of renal function were studied over a period of 2 years and were defined as: (i) improvement: >20% increase in estimated glomerular filtration rate (e-GFR) from presurgery value; (ii) stabilisation: e-GFR within 20% of presurgery value; and (iii) failure: >20% deterioration in e-GFR from presurgery value. The GFR was estimated using the Schwartz formula.Results. Twenty children (9 males and 11 females, age range 2 - 14 years) had 27 renal artery revascularisation procedures. Thirteen of the patients (65.0%) had bilateral renal artery stenosis. The baseline mean e-GFR was 88.6 (standard deviation (SD) 25.4) mL/min/1.73 m2 and the mean duration of follow-up was 28.80 (SD 25.62) months. All the patients had stable or improved renal function until the 2-year follow-up, when the proportion decreased to 92.3% (12/13), as failure was recorded in one child. Bilateral revascularisation was found to be significantly associated with improvement in renal function in the early postoperative period (p=0.04).Conclusion. Renal artery revascularisation procedures are successful in salvaging renal function in children with TARAS

Numerical modeling and simulation of seismic settlements on dense sands

Heavy components of nuclear power plant structures, in absence of rock stratum, may be founded on dense compacted granular materials. The seismic performance of such structures constructed on natural or compacted, dense sands depends on the cyclic shear stress - shear strain – volumetric strain response of the underlying soil. Dense natural or compacted coarse-grained soils are not expected to liquefy during an earthquake. However, accumulated volumetric strains within a deep deposit during multi-directional seismic loadings may lead to non-trivial settlements. In these situations, reliable estimations of seismic settlements are essential for assessing safety and serviceability of the structures. However, such settlements are not yet well understood due to limited number of studies for dense sands and the effects of multi-directionality. This dissertation describes the development of a new, three-dimensional constitutive model and application of three-dimensional nonlinear finite element analyses to estimate settlements in sands with and without structure conditions under uni/bi-directional seismic loadings. Constitutive model performance for liquefaction problems is also evaluated. The first part (Chapter 1 and Chapter 2) defines the engineering problem and reviews selected existing constitutive models, and a new, three-dimensional, distributed element plasticity-based, effective mean stress-dependent constitutive model (I-soil) is introduced for dense to very dense sands (Chapter 3). This constitutive model captures: (1) both Masing and non-Masing type hysteretic behavior; (2) small strain nonlinearity; and (3) shear-induced volumetric behavior including seismic settlements and excess porewater pressure generation/dissipation. I-soil uses distributed element plasticity (DEP) framework and does not require kinematic hardening rule. Thus, the mathematical formulation and numerical implementation is simple and efficient. The model is implemented in soil-fluid coupled dynamic finite element analysis platform LS-DYNA. The model parameters, defining shear stress – shear strain behavior, are determined using soil index properties, shear wave velocity, a normalized strain-dependent modulus reduction curve, and damping curve. Shear induced volumetric response is modelled using two additional parameters. Calibration of these parameters were achieved using 168 laboratory tests and 2730 calibration simulations utilizing statistical method for generating a near-random sample of parameter values (Chapter 4). Part two presents application of the developed model for boundary value problems including shear beam type free-field (Chapter 5) and three-dimensional soil -structure interaction (SSI) conditions with fluid coupling (Chapter 6). A single calibration was used for both free-field and SSI simulations. A unique centrifuge “case histories” were used to evaluate the model performance. The results show that the numerical models capture the uni and bi-directional responses in a shear beam and SSI in terms of energy intensities, peak ground accelerations and spectral acceleration with depth. Only two additional parameters for shear induced volumetric response allows finite element simulations to capture measured settlements, excess porewater pressures and effect of multi-directional loading on shear and volumetric behavior. In addition, energy intensities and three-dimensional strain information extracted from finite element analyses are shown to provide reliable information to proposed hybrid empirical and semi-empirical models on estimation of seismic settlements in free-field and with structure conditions. Run times for 3-D SSI simulations are within 6-22 hours using two logical core per event in a computer server. Part three (Chapter 7) presents finite element analysis of a liquefying site. Port Island case history was used to assess the constitutive and numerical model performance on estimating recorded response in a downhole array. The selected case history is the Port Island array response during the 1995 Kobe Earthquake. The recorded acceleration time histories and spectral response were compared to the computed counterparts. The numerical model was observed to capture the certain recorded behavior such as long period acceleration time histories and amplification in spectral accelerations at longer periods as well as de-amplification of PGA due to liquefaction. Stress-strain behavior observed from computed response show that the constitutive model is capable of producing “banana loops” which is result of effective mean stress dependent response of the constitutive model along with its capability of representing contractive-dilative tendency.LimitedAuthor requested closed access (OA after 2yrs) in Vireo ETD syste

Numerical modeling and simulation of seismic settlements on dense sands

Heavy components of nuclear power plant structures, in absence of rock stratum, may be founded on dense compacted granular materials. The seismic performance of such structures constructed on natural or compacted, dense sands depends on the cyclic shear stress - shear strain – volumetric strain response of the underlying soil. Dense natural or compacted coarse-grained soils are not expected to liquefy during an earthquake. However, accumulated volumetric strains within a deep deposit during multi-directional seismic loadings may lead to non-trivial settlements. In these situations, reliable estimations of seismic settlements are essential for assessing safety and serviceability of the structures. However, such settlements are not yet well understood due to limited number of studies for dense sands and the effects of multi-directionality. This dissertation describes the development of a new, three-dimensional constitutive model and application of three-dimensional nonlinear finite element analyses to estimate settlements in sands with and without structure conditions under uni/bi-directional seismic loadings. Constitutive model performance for liquefaction problems is also evaluated. The first part (Chapter 1 and Chapter 2) defines the engineering problem and reviews selected existing constitutive models, and a new, three-dimensional, distributed element plasticity-based, effective mean stress-dependent constitutive model (I-soil) is introduced for dense to very dense sands (Chapter 3). This constitutive model captures: (1) both Masing and non-Masing type hysteretic behavior; (2) small strain nonlinearity; and (3) shear-induced volumetric behavior including seismic settlements and excess porewater pressure generation/dissipation. I-soil uses distributed element plasticity (DEP) framework and does not require kinematic hardening rule. Thus, the mathematical formulation and numerical implementation is simple and efficient. The model is implemented in soil-fluid coupled dynamic finite element analysis platform LS-DYNA. The model parameters, defining shear stress – shear strain behavior, are determined using soil index properties, shear wave velocity, a normalized strain-dependent modulus reduction curve, and damping curve. Shear induced volumetric response is modelled using two additional parameters. Calibration of these parameters were achieved using 168 laboratory tests and 2730 calibration simulations utilizing statistical method for generating a near-random sample of parameter values (Chapter 4). Part two presents application of the developed model for boundary value problems including shear beam type free-field (Chapter 5) and three-dimensional soil -structure interaction (SSI) conditions with fluid coupling (Chapter 6). A single calibration was used for both free-field and SSI simulations. A unique centrifuge “case histories” were used to evaluate the model performance. The results show that the numerical models capture the uni and bi-directional responses in a shear beam and SSI in terms of energy intensities, peak ground accelerations and spectral acceleration with depth. Only two additional parameters for shear induced volumetric response allows finite element simulations to capture measured settlements, excess porewater pressures and effect of multi-directional loading on shear and volumetric behavior. In addition, energy intensities and three-dimensional strain information extracted from finite element analyses are shown to provide reliable information to proposed hybrid empirical and semi-empirical models on estimation of seismic settlements in free-field and with structure conditions. Run times for 3-D SSI simulations are within 6-22 hours using two logical core per event in a computer server. Part three (Chapter 7) presents finite element analysis of a liquefying site. Port Island case history was used to assess the constitutive and numerical model performance on estimating recorded response in a downhole array. The selected case history is the Port Island array response during the 1995 Kobe Earthquake. The recorded acceleration time histories and spectral response were compared to the computed counterparts. The numerical model was observed to capture the certain recorded behavior such as long period acceleration time histories and amplification in spectral accelerations at longer periods as well as de-amplification of PGA due to liquefaction. Stress-strain behavior observed from computed response show that the constitutive model is capable of producing “banana loops” which is result of effective mean stress dependent response of the constitutive model along with its capability of representing contractive-dilative tendency.LimitedAuthor requested closed access (OA after 2yrs) in Vireo ETD syste