Inflation of 430-parsec bipolar radio bubbles in the Galactic Centre by an energetic event.

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.

Evaluating the genetic consequences of population subdivision as it unfolds and how to best mitigate them: A rare story about koalas.

The genetic consequences of the subdivision of populations are regarded as significant to long-term evolution, and research has shown that the scale and speed at which this is now occurring is critically reducing the adaptive potential of most species which inhabit human-impacted landscapes. Here, we provide a rare and, to our knowledge, the first analysis of this process while it is happening and demonstrate a method of evaluating the effect of mitigation measures such as fauna crossings. We did this by using an extensive genetic data set collected from a koala population which was intensely monitored during the construction of linear transport infrastructure which resulted in the subdivision of their population. First, we found that both allelic richness and effective population size decreased through the process of population subdivision. Second, we predicted the extent to which genetic drift could impact genetic diversity over time and showed that after only 10 generations the resulting two subdivided populations could experience between 12% and 69% loss in genetic diversity. Lastly, using forward simulations we estimated that a minimum of eight koalas would need to disperse from each side of the subdivision per generation to maintain genetic connectivity close to zero but that 16 koalas would ensure that both genetic connectivity and diversity remained unchanged. These results have important consequences for the genetic management of species in human-impacted landscapes by showing which genetic metrics are best to identify immediate loss in genetic diversity and how to evaluate the effectiveness of any mitigation measures.

Challenges of implementing an integrated electronic health record system in the Breast and Endocrine Clinic at Tygerberg Hospital, Cape Town, South Africa.

To the Editor: In low- to middle-income countries, the majority of patients with breast cancer are diagnosed with locally advanced disease. This remains a problem at the Tygerberg Hospital breast clinic in Cape Town, South Africa, with ~60% of all patients presenting with stage 3 or 4 disease at the time of diagnosis. The reasons cited are multiple and include fear, unawareness of disease severity, concerns surrounding losing a breast, unreliable transportation, referral difficulties and financial constraints.[1].

Geometric Variations of Modular Head-Stem Taper Junctions of Total Hip Replacements.

Taper degradation in Total Hip Replacements (THR) has been identified as a clinical concern, and the degradation occurring at these interfaces has received increased interest in recent years. Wear and corrosion products produced at the taper junction are associated with adverse local tissue responses, leading to early failure and revision surgery. Retrieval and in-vitro studies have found that variations in taper design affect degradation. However, there is a lack of consistent understanding within the literature of what makes a good taper interface. Previous studies assessed different design variations using their global parameters assuming a perfect cone such as: taper length, cone angle and diameters. This study assessed geometrical variations of as-manufactured head and stem tapers and any local deviations from their geometry. The purpose of this study was to provide a greater insight into possible engagement, a key performance influencing parameter predicted by Morse taper connection theory. This was achieved by taking measurements of twelve different commercially available male tapers and six female tapers using a coordinate measurement machine (CMM). The results suggested that engagement is specific to a particular head-stem couple. This is subject to both their micro-scale deviations, superimposed on their macro-scale differences. Differences in cone angles between female and male tapers from the same manufacturer was found to create a predominately proximal contact. However, distally mismatched couples are present in some metal-on-metal head-stem couples. On a local scale, different deviation patterns were observed from the geometry which appeared to be linked to the manufacturing process. Future work will look at using this measurement methodology to fully characterise an optimal modular taper junction for a THR prosthesis.

Provision of acute and elective general surgical care at a tertiary facility in the era of subspecialisation.

BACKGROUND: The need for an acute care and general surgical unit (ACGSU) to provide care for patients previously managed on an ad hoc basis by subspecialist units was recognised by the provincial government of the Western Cape Province, South Africa, the management of Groote Schuur Hospital (GSH) and the Department of Surgery. OBJECTIVE: To describe the resulting ACGSU and its functioning. METHODS: Data available from administrative records, patient files and operating room forms were collected in spreadsheet form for the period July 2013 - November 2016 inclusive. RESULTS: The ACGSU comprised a medical care team of four consultants and four to five trainees. A total of 7 571 patients were seen during the study period, the majority (66.1%) referred from the GSH Emergency Centre. Skin and soft-tissue infections formed the major disease complex. A total of 3 144 operative records were available. The most common procedures were wound debridement and inguinal hernia repairs. Trainees acted as primary surgeon in most cases. Complications (Clavien-Dindo grades I - V) were noted in 25.0% of patients. CONCLUSIONS: The ACGSU provides patient management that would otherwise complicate care in the subspecialist surgical units. It serves as a training ground for registrars and stands as a model for other institutions. Further research into the effect on patient care is planned.

Proximal versus distal screw placement for biceps tenodesis: a biomechanical study.

PURPOSE: To assess the maximum and end torque of a fourth-generation composite humerus model with no screw inserted or with a screw inserted in the distal (subpectoral) position or proximal (suprapectoral) position. METHODS: 24 large-size, fourth-generation composite humeri were randomised to the control (n=8), proximal (n=8), or distal (n=8) group. For the latter 2 groups, an 8-mm-head interference screw (7x25 mm) was inserted at 1 cm proximal and 1 cm distal to the superior aspect of the insertion of the pectoralis major tendon, respectively. The maximum and end torque of each humerus was assessed. RESULTS: Respectively for the control, proximal, and distal groups, the maximum torque was 81.8, 78.7, and 74.3 Nm, and the end torque was 80.7, 78.6, and 71.8 Nm; only the difference between control and distal groups was significant (p=0.005 for maximum torque and p=0.033 for end torque). All fractures in both control and proximal groups involved the distal 1/3 humerus. In the distal group, the fractures involved either the distal 1/3 humerus (n=6) or the screw-hole (n=2); the difference between the 2 types of fracture was not significant in terms of maximum torque (75.7 vs. 70.0, p=0.086) or end torque (75.3 vs. 61.4, p=0.40). CONCLUSION: Compared with proximal placement of an interference screw, distal placement decreased the maximum torque (though not significantly) and may increase the risk of proximal humeral fracture.

Clinical and laboratory characteristics of HIV-1 infection in Zimbabwe.

To define the impact of human immunodeficiency virus (HIV) infection in Africa, clinical and laboratory investigations were conducted on 265 HIV-seropositive outpatients in Zimbabwe. Twenty-four of the study subjects were asymptomatic (ASX), 124 had persistent generalized lymphadenopathy (PGL), and 117 had AIDS-related complex (ARC). HIV infection was assessed by commercial ELISA, Western blots, synthetic peptide ELISA, and measurement of p24 antigen. Serum immunoglobulins, lymphocyte mitogen responses, and CD4+ cell numbers were obtained in 54 sequential patients. Compared to seronegative subjects, mean CD4+ cell numbers were decreased and serum immunoglobulins, particularly IgM and IgG, were increased in all groups of seropositive subjects. Lymphocyte proliferative responses to phytohemagglutinin and concanavalin A decreased progressively in ASX, PGL, and ARC patients and were significantly lower in PGL and ARC patients compared to seronegative controls. Generalized lymphadenopathy was present in 234/265 (88%) of patients. Lymph node biopsies in 100 patients demonstrated follicular hyperplasia in 97 and Mycobacterium tuberculosis in 3. Of 165 patients followed for a median of 6 months, 5 developed the acquired immune deficiency syndrome (AIDS). Symptoms of ARC, low CD4+ cell number, and p24 antigen were predictive of the development of AIDS in Zimbabwe.

Photocatalytic degradation of cyanobacterial microcystin toxins in water.

The microcystins are hepatotoxins produced by a number of cyanobacterial species (blue green algae) in fresh water systems. The increasing eutrophication of natural waters has led to an increase in the incidence of algal blooms and the consequent increased risk of microcystin contamination of water resources. The removal of microcystins LR, YR and YA from contaminated water was investigated using an experimental laboratory-scale photocatalytic 'falling film' reactor in which an oxygen purge, UV radiation and semiconductor titanium dioxide (TiO2) catalyst were used to oxidatively decompose the microcystin pollutants. Preliminary studies, using algal extracts spiked into distilled water, indicated that the microcystins were rapidly decomposed in this reactor. The decomposition followed first order reaction kinetics with half-lives of less than 5 min with the reactor operating in a closed-loop mode. Reaction rates were strongly dependent on the amount of TiO2 catalyst (O-5 g/l), but only marginally influenced by a change in gas purge from oxygen to compressed air. The use of lake water, rather than distilled water, showed that this process is feasible in natural waters, although increased levels of catalyst (up to 5 g/l) were required to achieve comparable decomposition rates.

The natBr(p,x) (73,75)Se nuclear processes: a convenient route for the production of radioselenium tracers relevant to amino acid labelling.

A possible route for the production of no-carrier-added (n.c.a.) 73Se (T(1/2) = 7.1 h) and 75Se (120 d) is introduced. D,L-2-Amino-4-([73Se]methyl-seleno) butanoic acid (D,L-[73Se]selenomethionine) with an overall radiochemical yield of > 40% could be prepared via a 3-step polymer-supported synthesis after successful separation of 73Se from KBr targets. Excitation functions for the natBr(p,x) (72,73,75)Se processes were measured from threshold up to 100 MeV utilizing pellets of pressed KBr. Targets were irradiated at the NAC cyclotron with proton beams having primary energies of 40.4, 66.8 and 100.9 MeV. The calculated 73Se yield (EOB) for 1 h irradiation in 1 microA of beam at the optimum proton energy range of 62-->42 MeV is 81.4 MBq (2.2 mCi), and the calculated 75Se yield (EOB) for the overall range 62 MeV-->threshold for the same irradiation conditions is 0.97 MBq (0.026 mCi).

The prevalence of Herpes simplex virus type-2 infection in blood donors in Harare, Zimbabwe.

OBJECTIVE: To determine the prevalence of HSV-2 infections in a population of blood donors. DESIGN: Cross sectional study. SETTING: Harare Blood Transfusion Service (BTS) Centre. SUBJECTS: 314 serum specimens of voluntary blood donors. MAIN OUTCOME MEASURES: HSV-2 sero-prevalence. RESULTS: The median age (Q1, Q3) of the blood donors was 18 (17,27) years and 65% of them were males. HSV-2 infection was detected in 29 (9.7%) of the 299 specimens that were analyzed. There was a strong association between age of blood donors and HSV-2 seropositivity (p < 0.001). Older blood donors tended to be positive while younger donors tended to be negative for HSV-2 antibodies. Though not as strong, there was also an association between HSV-2 and HIV seropositivity (p = 0.048). CONCLUSION: The prevalence of HSV-2 infections in blood donors in Harare is high, considering the nature of the population studied. Therefore, the testing for HSV-2 in the serum of prospective blood donors should be included in the screening profiles used at the BTS centre in Harare, Zimbabwe to improve blood and blood products.

Nocardiosis. Case report and review of the diagnosis and treatment.

Purulent draining skin sinuses are a striking clinical finding when Nocardia organisms infect skin or deeper tissues and the lesion is often mistakenly ascribed to actinomycotic infection. This distinction is important because in contrast to actinomycosis, nocardiosis does not respond to treatment with penicillin or most antibiotics, and a fulminating systemic infection may occur. Smears made from purulent discharges do not always show the organism and microbiological culture may likewise prove fruitless. This article reports a patient suffering from nocardiosis and the pitfalls in diagnosis are illustrated. Successful culture of the organism was obtained by inoculating media with fresh biopsy material and a plea is made for routine use of this method. The need to use sulphadiazine in high doses initially, followed by maintenance treatment for considerable time, is emphasized.

Malignant melanoma in a child. A case report.

The rare occurrence of malignant melanoma in a child is reported. Differentiation on histopathological grounds between this tumour and the more common juvenile melanoma may be difficult, but this important distinction should be possible in almost all cases.

Interaction and inhibition of acetylcholinesterase from Electrophorus electricus by nitrosamines.

Kinetic analysis has shown that dimethylnitrosamine, dipropylnitrosamine, dibutylnitrosamine, and diphenylnitrosamine initially act as reversible competitive inhibitors with respect to the substrate, acetylthiocholine chloride. The inhibitor constants Ki vary from 21-30 microM for the aliphatic nitrosamines to 8.2 microM for the aromatic diphenylnitrosamine. With time they act as irreversible covalent inhibitors with dimethylnitrosamine producing 82% inactivation after 40 min. Pseudo-first-order kinetics are observed with the rate constant being proportional to the concentration of the nitrosamine and the order of reaction being equal to one. Fluorometry, gel chromatography, and equilibrium dialysis have been used to study the binding of the nitrosamines with acetylcholinesterase. Scatchard analysis indicates that dimethyl-, dipropyl-, and dibutylnitrosamine have a weaker affinity for the enzyme (Kd 5.6-8.08 microM) compared to diphenylnitrosamine (Kd 2.32 microM). In all cases the number of binding sites was four.

Kaposi's sarcoma in Zimbabwe. II. Peripheral lymphocytes, immunoglobulin G levels and HIV antibody positivity.

Patients with Kaposi's Sarcoma (KS) were grouped according to their clinical symptoms into "indolent", "locally aggressive", "endemic generalised aggressive" and "epidemic generalised aggressive" disease. Only the patients in the epidemic generalised aggressive disease group had serum antibodies to HIV. Complete peripheral blood counts, including lymphocyte subsets, and serum IgG assays were performed on all patients before treatment was initiated. In all the aggressive disease groups there was evidence of immune deficiency in that T helper/inducer (T4) cells were reduced leading to reduced T4,T8 (suppresser/cytotoxic) ratio. All patient groups had increased levels of serum IgG. Although immune deficiency and aggressive KS can be explained in the HIV infected patients no underlying cause has been found in the HIV negative patients with aggressive KS.

Circulating progesterone concentrations and ovarian functional anatomy in the African elephant (Loxodonta africana).

Mean plasma progesterone concentrations measured in pregnant and non-pregnant elephants did not differ significantly from each other because of considerable variation, particularly for stage of pregnancy. Maximum progesterone values were recorded during pregnancy (5-8 months) and declined towards term (22 months). The numbers of corpora lutea or total luteal tissue volume were not critical in maintaining progesterone secretion. An increase in plasma progesterone concentrations with the luteal phase of the ovarian cycle was evident. A possible role of the placenta in the second half of gestation is indicated by an increase in fetal progesterone concentrations towards term.

Complement activation in chronic liver disease.

Patients with HBsAg positive chronic active liver disease (CALD) and primary biliary cirrhosis (PBC) exhibit increased C3d concentrations and changes in the serum concentrations of the complement components consistent with activation of the classical and alternative pathways. In these patients the concentrations of the regulatory proteins, C3b inactivator (C3bINA) and beta IH globulin, are normal. Patients with HBsAg negative CALD and alcohol induced liver disease (ALD) exhibit no evidence of an increased level of complement system activation. In these patients diminished serum concentrations of complement components appear to be related to diminished hepatic synthetic function. C4 synthesis may be specifically reduced in autoimmune chronic active liver disease.

Monomeric (7S) IgM in chronic liver disease.

Monomeric (7S) IgM was detected by polyacrylamide/agarose gell immunodiffusion and Sephadex G200 gel filtration in 33% of sera from patients with primary biliary cirrhosis (PBC) and 5% of patients with HBsAg-negative chronic active liver disease (CALD). It was not found in the sera of patients with extrahepatic cholestasis, alcoholic liver disease (ALD), HBsAg-positive CALD and normal control subjects. In the PBC group the presence of 7S IgM was associated with significantly higher IgM concentrations and Clq binding activity (P less than 0.001; P less than 0.01 respectively). The antibody specificity of the 7S IgM is unknown. Its presence in patients with high serum IgM concentrations probably reflects failure of complete polymerisation of 7S IgM because of an increased rate of synthesis of the protein. The association of the presence of 7S IgM and high total IgM with immune complexes suggests that the increased rate of synthesis of IgM and formation of immune complexes probably are a result of the same antigenic (or mitogenic) stimulus.

Relationship between non-antigen-specific immunodepression and persisting immune complexes induced by pertussis in mice.

A temporal relationship has been demonstrated between persisting immune complexes and non-antigen-specific immunodepression. Mice were given intraperitoneal injections of Bordetella pertussis at weekly intervals. After 7 weeks they developed circulating immune complexes, the levels of which increased with continued administration of pertussis. The increase in immune complex levels was accompanied by a diminished primary immune response to intraperitoneally injected sheep erythrocytes (SRBC) as judged by a reduction in their direct and indirect plaque-forming cell response and serum agglutination titres. Spleen cells from immunodepressed pertussis-treated mice were transferred to irradiated normal recipients and displayed a normal response to SRBC. By contrast, spleen cells transferred from normal donors to irradiated pertussis-treated recipients had an impaired response to SRBC. Thus, the immunodepression caused by pertussis treatment is a property of the environment and not the lymphocytes themselves. It is considered that chronic circulating immune complexes induced by pertussis administration may cause non-antigen-specific immunodepression.

[The effect of bonded and nonbonded posts on the fracture resistance of dentin]. / Die effek van gebonde en ongebonde stiwwe op die fraktuurweerstand van dentien.

This in vitro study determined the effect of bonded and non-bonded cast, serrated, tin plated, parallel gold posts on the fracture resistance of surrounding dentine walls. Specimens were divided into two groups. One group's posts were luted with zinc phosphate cement and the other group's posts were tin-plated and adhesively bonded with an adhesive resin cement. Three different dentine wall thicknesses, namely 0.5 mm, 0.75 mm and 1.0 mm were prepared, subdividing the specimens of each main group into three subgroups. Specimens were subjected to a 50 degrees oblique force. The force required to fracture the dentinal walls was registered. There was no statistically significant differences in the fracture resistance of dentine with the two different cements or of the different dentine wall thicknesses.