No evidence for naturally occurring mutations resistant to HIV-1 reverse-transcriptase inhibitors among South African HIV-1 subtype C isolates

[No abstract available

Intra- and Inter-clade Cross-reactivity by HIV-1 Gag Specific T-Cells Reveals Exclusive and Commonly Targeted Regions: Implications for Current Vaccine Trials

The genetic diversity of HIV-1 across the globe is a major challenge for developing an HIV vaccine. To facilitate immunogen design, it is important to characterize clusters of commonly targeted T-cell epitopes across different HIV clades. To address this, we examined 39 HIV-1 clade C infected individuals for IFN-γ Gag-specific T-cell responses using five sets of overlapping peptides, two sets matching clade C vaccine candidates derived from strains from South Africa and China, and three peptide sets corresponding to consensus clades A, B, and D sequences. The magnitude and breadth of T-cell responses against the two clade C peptide sets did not differ, however clade C peptides were preferentially recognized compared to the other peptide sets. A total of 84 peptides were recognized, of which 19 were exclusively from clade C, 8 exclusively from clade B, one peptide each from A and D and 17 were commonly recognized by clade A, B, C and D. The entropy of the exclusively recognized peptides was significantly higher than that of commonly recognized peptides (p = 0.0128) and the median peptide processing scores were significantly higher for the peptide variants recognized versus those not recognized (p = 0.0001). Consistent with these results, the predicted Major Histocompatibility Complex Class I IC50 values were significantly lower for the recognized peptide variants compared to those not recognized in the ELISPOT assay (p<0.0001), suggesting that peptide variation between clades, resulting in lack of cross-clade recognition, has been shaped by host immune selection pressure. Overall, our study shows that clade C infected individuals recognize clade C peptides with greater frequency and higher magnitude than other clades, and that a selection of highly conserved epitope regions within Gag are commonly recognized and give rise to cross-clade reactivities

Hardness Evaluation of Porous Hydroxyapatite Coating

The extensive use of appropriate coatings to improve wear resistance, friction coefficient, electrical properties, corrosion resistance and biomedical application has stimulated a growing interest in their mechanical properties and especially hardness testing that is routinely used for coating evaluation. In this study Jönsson and Hogmark model is applied for the porous hydroxyapatite produced by plasma spraying on Ti6A14V substrate. Firstly, the effect of indentation load on hardness values of coating and substrate are studied. The modified Jönsson and Hogmark model is used to explain the composite hardness behavior and the effect of coating porosity

Nanocolloidal albumin-IRDye 800CW: a near-infrared fluorescent tracer with optimal retention in the sentinel lymph node

Purpose: At present, the only approved fluorescent tracer for clinical near-infrared fluorescence-guided sentinel node (SN) detection is indocyanine green (ICG), but the use of this tracer is limited due to its poor retention in the SN resulting in the detection of higher tier nodes. We describe the development and characterization of a next-generation fluorescent tracer, nanocolloidal albumin-IRDye 800CW that has optimal properties for clinical SN detection Methods: The fluorescent dye IRDye 800CW was covalently coupled to colloidal human serum albumin (HSA) particles present in the labelling kit Nanocoll in a manner compliant with current Good Manufacturing Practice. Characterization of nanocolloidal albumin-IRDye 800CW included determination of conjugation efficiency, purity, stability and particle size. Quantum yield was determined in serum and compared to that of ICG. For in vivo evaluation a lymphogenic metastatic tumour model in rabbits was used. Fluorescence imaging was performed directly after peritumoral injection of nanocolloidal albumin-IRDye 800CW or the reference ICG/HSA (i.e. ICG mixed with HSA), and was repeated after 24 h, after which fluorescent lymph nodes were excised. Results: Conjugation of IRDye 800CW to nanocolloidal albumin was always about 50% efficient and resulted in a stable and pure product without affecting the particle size of the nanocolloidal albumin. The quantum yield of nanocolloidal albumin-IRDye 800CW was similar to that of ICG. In vivo evaluation revealed noninvasive detection of the SN within 5 min of injection of either nanocolloidal albumin-IRDye 800CW or ICG/HSA. No decrease in the fluorescence signal from SN was observed 24 h after injection of the nanocolloidal albumin-IRDye 800CW, while a strong decrease or complete disappearance of the fluorescence signal was seen 24 h after injection of ICG/HSA. Fluorescence-guided SN biopsy was very easy. Conclusion: Nanocolloidal albumin-IRDye 800CW is a promising fluorescent tracer with optimal kinetic features for SN detection. © The Author(s) 2012

The Ahlmannryggen group, the viddalen formation and the associated igneous rocks in the viddalen area, western droning Maud land, Antarctica

Nunataks within an area of approximately 3 400 km2 between latitudes 71°50' and 72°35' south and longitudes 1°30' and 4°00' west were mapped geologically by the 12th South African National Antarctic Expedition during the summer of 1971-72. The area is underlain mainly by subhorizontal arenaceous and argillaceous sediments, extensively intruded by thick mafic sills and dykes of Precambrian age. An isolated succession comprising agglomerate, tuff and lava flows with intercalated sediments in its upper part is exposed in the east and south. A new lithostratigraphic subdivision is proposed, based on detailed investigation of field relationships combined with subsequent petrological studies and radiometric age determinations. The oldest rocks in the area belong to the Pyramiden Formation which consists mostly of feldspathic graywacke and siltstone. Correlates of this formation were discovered at Kjolrabbane, Babordsranten and at Nashornet and Viddalskollen. At the latter locality the sequence is subdivided into a Lower Member, 140 m thick, deposited under low-energy, deep-water conditions, and an Upper Member, 250 m thick, which was deposited in shallower water under higher energy conditions .. The overlying Grunehogna Formation has the widest distribution of all sedimentary formations in the area and consists of alternating persistent beds of light-coloured arenite and dark-coloured argillite. This succession is conformably overlain by the H6gfonna Formation which is subdivided into a lower, Borgmassivet Member, consisting of feldspathic quartzite, shale and jasper-bearing conglomerate, and an upper, Jekselen Member which consists of calcareous, jasperbearing arenaceous sediments. All the formations mentioned above are assigned to the Ahlmannryggen Group. It is suggested that the Raudberget Formation, which is not exposed in the area investigated, is also included in this Group. The volcanic-sedimentary succession at Tindeklypa and Istind is believed to overlie the Hogfonna Formation conformably and is collectively called the Viddalen Formation. It is subdivided into two conformable members: a lower, Tindeklypa Member, some 500 m thick, which consists of agglomerate with subordinate tuff and andesitic lava flows, and an upper, Istind Member, 340 m thick, consisting of alternating feldspathic quartzite, agglomerate, tuff and lava flows. (ii) A continuous upward gradation from plutonic through hypabyssal to volcanic rock (near-surface intrusions) was detected in the 1 700 My mafic sill (Krylen Intrusions) at Jekselen. The lava flows in the Viddalen Formation are believed to be the volcanic equivalent of the Krylen Intrusions. Two samples of Krylen Intrusions from Jekselen and Istind were submitted for 40 Ar/39 Ar wholerock age determinations. Ages of 1 339 ±. 55 My and 603 ±.. 12 My respectively were computed, both being minimum ages resulting from complete overprinting by metamorphism. The majority of the large mafic intrusions in the area are believed to have an age of around 1 000 My and are called Ytstenut Intrusions. Minor felsic intrusions are also included under this heading as they were found to represent only local remobilised differentiation products formed by the reaction between the mafic intrusions and the sediments. Two samples of Ytstenut Intrusions from Grunehogna and Ytstenut were submitted for 40 Ar/39 Ar whole-rock age determinations. Minimum ages of 83 2 .±. 2 and 924 .± 4 My respectively were obtained; the latter age was regarded by the analysts as being close to the real date of intrusion. The youngest rocks in the area are represented by minor dolerite dykes of Jurassic age and are called Post-Ytstenut Intrusions.Dissertation (MSc)--University of Pretoria, 1976.GeologyMScUnrestricte

THE GENUS <i>ELYONURUS</i> Humb. and Bonpl. IN SOUTH AFRICA.

No abstract availabl

A new species of <i>Phaeoramularia</i> (Fungi Imperfecti: Dematiaceae) from South Africa

A dematiaceous Hyphomycete isolated fro n wheat and oat straw, as well as lucerne seed in South Africa, is described as Phaeoramularia kellermaniana Marasas & Bred ill, sp. nov. The relationships ofP. kellermaniana to  Cladosporium resinae (Lindau) de Vries and other species of Phaeoramularia are discussed

Human herpesvirus-8 antibodies and DNA in HIV-1 infected patients in South Africa

HIV-infected individuals with high levels of IgG antibodies against human herpesvirus-8 (HHV-8) are at increased risk of developing Kaposi's sarcoma. The aim of this study was to measure the association between HHV-8 viraemia and IgG antibody responses (by immunofluorescence) in a group of 201 HIV-infected individuals attending outpatient clinics, 91 in-patients with AIDS and 87 HIV-infected patients admitted with Kaposi's sarcoma. Compared to HIV-infected outpatients, the adjusted odds ratio in relation to Kaposi's sarcoma was 15.4 (95% CI 4.4-54.2) in those with viraemia, 25.1 (95% CI 6.6-95.6) in those with a positive immunofluorescent signal and infinity (lower exact CI 33.6) in those with a high immunofluorescent signal (all P trend < 0.001). Among those without HHV-8 viraemia, 23% were IgG-positive, but only 5.5% had a high immunofluorescent signal. In those who were viraemic, 89.1% were IgG-positive, and 28.2% had a high immunofluorescent signal, suggesting viraemia is associated with high HHV-8 immunofluorescence IgG signa

Comparison between umbilical artery and vein endogenous digoxin-like immuno-active factor levels in normal and pre-eclamptic patients

CITATION: Schabort, I. et al. 1991. Comparison between umbilical artery and vein endogenous digoxin-like immuno-active factor levels in normal and pre-eclamptic patients. South African Medical Journal, 71:197-199.The original publication is available at http://www.samj.org.zaRecent studies have pointed to the existence of an endogenous digoxin-like immuno-active factor (DLIF), which may be associated with hypertension and pre-eclampsia. The DLIF levels in the umbilical venous and umbilical arterial blood of neonates, as well as the maternal serum of primigravidas and multigravidas with and without pre-eclampsia, were determined by means of a commercially available radioimmunoassay kit, which is cross-reactive with DLIF, in 44 mothers and their babies in search for a possible placental, fetal or maternal origin of the DLIF. The mean placental and neonatal masses were significantly lower in the pre-eclampsia group than in the control group (P < 0,01). However, the DLIF levels in the maternal serum, umbilical cord venous and umbilical cord arterial serum were statistically significantly higher in the pre-eclampsia group than in the control pregnant group (P < 0,05). A very strong correlation was found between umbulical cord venous and arterial DLIF levels (r = 0,90; P = 0,001, Spearman rank-correlation coefficient). Although the mean DLIF level in cord arterial serum was lower than that of cord venous serum, statistical significance was not reached if the Bonferroni adjustment was applied to the P value.Publisher’s versio