Atypical presentation of angiosarcoma of the scalp in the setting of Human Immunodeficiency Virus (HIV)

Background

Splenosis is a heterotropic implantation of splenic fragments onto exposed vascularised peritoneal and intrathoracic surfaces, following splenic injury or elective splenectomy.

Case presentation

A 60 year old cirrhotic patient was referred to us with a hepatic mass, suspected to be HCC in a cirrhotic liver. A computerized tomography scan (CT) demonstrated a cirrhotic liver with a 2 × 2.7 cm focal hypervascular nodule, lying peripherally at the junction of segment 7 and 8. Diagnostic laparoscopy demonstrated a 3 cm exofitic dark brown splenunculus attached to the diaphragm and indenting the surface of segment 7 of the liver. The lesion was easily resected laparoscopically and shaved from the live surface with no need for a liver resection. The histopathological assessment confirmed the diagnosis of splenunculus, with no evidence of neoplasia.

Conclusion

Hepatic splenosis is not a rare event and should be suspected in patients with a history of splenic trauma or splenectomy. Correct diagnosis is essential and will determine subsequent management plans. In doubtful cases laparoscopic investigation can offere essential information and should be part of the standard protocol for investigating suspected splenosis.     

The influence of fire frequency on the structure and botanical composition of savanna ecosystems

Savannas cover 60% of the land surface in Southern Africa, with fires and herbivory playing a key role in their ecology. The Limpopo National Park (LNP) is a 10,000 km² conservation area in southern Mozambique and key to protecting savannas in the region. Fire is an important factor in LNP's landscapes, but little is known about its role in the park's ecology. In this study, we explored the interaction between fire frequency (FF), landscape type, and vegetation. To assess the FF, we analyzed ten years of the Moderate resolution Imaging Spectroradiometer (MODIS) burned area product (2003–2013). A stratified random sampling approach was used to assess biodiversity across three dominant landscapes (Nwambia Sandveld‐NS, Lebombo North‐LN, and Shrubveld Mopane on Calcrete‐C) and two FF levels (low—twice or less; and high—3 times or more, during 10 years). Six ha were sampled in each stratum, except for the LN versus high FF in which low accessibility allowed only 3 ha sampling. FF was higher in NS and LN landscapes, where 25% and 34% of the area, respectively, burned more than three times in 10 years. The landscape type was the main determinant of grass composition and biomass. However, in the sandy NS biomass was higher under high FF. The three landscapes supported three different tree/shrub communities, but FF resulted in compositional variations in NS and LN. Fire frequency had no marked influence on woody structural parameters (height, density, and phytomass). We concluded that the savannas in LNP are mainly driven by landscape type (geology), but FF may impose specific modifications. We recommend a fire laissez‐faire management system for most of the park and a long‐term monitoring system of vegetation to address vegetation changes related to fire. Fire management should be coordinated with the neighboring Kruger National Park, given its long history of fire management. Synthesis: This study revealed that grass and tree/shrub density, biomass, and composition in LNP are determined by the landscape type, but FF determines some important modifications. We conclude that at the current levels FF is not dramatically affecting the savanna ecosystem in the LNP (Figure 1). However, an increase in FF may drive key ecosystem changes in grass biomass and tree/shrub species composition, height, phytomass, and density.     

Solid-phase peptide synthesis (SPPS), C-terminal vs. side-chain anchoring: a reality or a myth

Here we review the strategies for the solid-phase synthesis of peptides starting from the side chain of the C-terminal amino acid. Furthermore, we provide experimental data to support that C-terminal and side-chain syntheses give similar results in terms of purity. However, the stability of the two bonds that anchor the peptide to the polymer may determine the overall yield and this should be considered for the large-scale production of peptides. In addition, resins/linkers which do not subject to side reactions can be preferred for some peptides.     

A test of two mechanisms proposed to optimize grassland aboveground primary productivity in response to grazing

Aims Mesic grasslands have a long evolutionary history of grazing by large herbivores and as a consequence, grassland species have numerous adaptations allowing them to respond favourably to grazing. Although empirical evidence has been equivocal, theory predicts that such adaptations combined with alterations in resources can lead to grazing-induced overcompensation in aboveground net primary production (ANPP; grazed ANPP> ungrazed ANPP) under certain conditions. We tested two specific predictions from theory. First, overcompensation is more likely to occur in annually burned grasslands because limiting nutrients that would be lost with frequent fires are recycled through grazers and stimulate ANPP. Second, overcompensation of biomass lost to grazers is more likely to occur in unburned sites where grazing has the greatest effect on increasing light availability through alterations in canopy structure.Methods We tested these nutrient versus light-based predictions in grazed grasslands that had been annually burned or protected from fire for>20 years. We assessed responses in ANPP to grazing by large ungulates using both permanent and moveable grazing exclosures (252 exclosures from which biomass was harvested from 3192 quadrats) in a 2-year study. Study sites were located at the Konza Prairie Biological Station (KPBS) in North America and at Kruger National Park (KNP) in South Africa. At KPBS, sites were grazed by North American bison whereas in KNP sites were grazed either by a diverse suite of herbivores (e.g. blue wildebeest, Burchell's zebra, African buffalo) or by a single large ungulate (African buffalo).Important findings We found no evidence for overcompensation in either burned or unburned sites, regardless of grazer type. Thus, there was no support for either mechanism leading to overcompensation. Instead, complete compensation of total biomass lost to grazers was the most common response characterizing grazing–ANPP relationships with, in some cases, undercompensation of grass ANPP being offset by increased ANPP of forbs likely due to competitive release. The capability of these very different grass-dominated systems to maintain ANPP while being grazed has important implications for energy flow, ecosystem function and the trophic dynamics of grasslands.     

Molecular type distribution and fluconazole susceptibility of clinical Cryptococcus gattii isolates from South African laboratory-based surveillance, 2005–2013

As is the case globally, Cryptococcus gattii is a less frequent cause of cryptococcosis than Cryptococcus neoformans in South Africa. We performed multilocus sequence typing (MLST) and fluconazole susceptibility testing of 146 isolates randomly selected from 750 South African patients with C. gattii disease identified through enhanced laboratory surveillance, 2005 to 2013. The dominant molecular type was VGIV (101/146, 70%), followed by VGI (40/146, 27%), VGII (3/146, 2%) and VGIII (2/146, 1%). Among the 146 C. gattii isolates, 99 different sequence types (STs) were identified, with ST294 (14/146, 10%) and ST155 (10/146, 7%) being most commonly observed. The fluconazole MIC₅₀ and MIC₉₀ values of 105 (of 146) randomly selected C. gattii isolates were 4 μg/ml and 16 μg/ml, respectively. VGIV isolates had a lower MIC₅₀ value compared to non-VGIV isolates, but these values were within one double-dilution of each other. HIV-seropositive patients had a ten-fold increased adjusted odds of a VGIV infection compared to HIV-seronegative patients, though with small numbers (99/136; 73% vs. 2/10; 20%), the confidence interval (CI) was wide (95% CI: 1.93–55.31, p = 0.006). Whole genome phylogeny of 98 isolates of South Africa’s most prevalent molecular type, VGIV, identified that this molecular type is highly diverse, with two interesting clusters of ten and six closely related isolates being identified, respectively. One of these clusters consisted only of patients from the Mpumalanga Province in South Africa, suggesting a similar environmental source. This study contributed new insights into the global population structure of this important human pathogen.     

Analysis of the conformational profile of trishomocubane amino acid dipeptide

4-Amino-(D3)-trishomocubane-4-carboxylic acid is a constrained alpha-amino acid residue that exhibits promising conformational characteristics, i.e., helical and beta-turns. As part of the development of conformational guidelines for the design of peptides and protein surrogates, the conformational energy calculations on trishomocubane using molecular mechanics and ab initio methods are presented. The C(alpha) carbon of trishomocubane forms part of the cyclic structure, and consequently a peptidic environment was simulated with an acetyl group on its N-terminus and a methylamide group on its C-terminus. Ramachandran maps computed at the molecular mechanics level using the standard AMBER (parm94) force field libraries compared reasonably well with the corresponding maps computed at the Hartree Fock level, using the 6-31G* basis set. Trishomocubane peptide (Ac-Tris-NHMe) is characterized by four low energy conformers corresponding to the C7ax, C7eq, 3(10), and alpha(L) helical structures.     

Reproductive biology of longnose trevally (Carangoides chrysophrys) in the Arabian Sea, Oman

The reproductive pattern of longnose trevally (Carangoides chrysophrys) in the Arabian Sea, off the coast of Oman, is described. Samples were collected on a monthly base between April 2005 and September 2006 from two landing sites (ALlakbi and Raysuot). A single peak of the gonadosomatic index (GSI) started from September and ended in February signalling the spawning period. Values of the relative condition factor (K _n ) were fairly constant throughout the year for both males and females and no significantly difference was found in the average K _n values between males and females during sampling period. Male and female lengths-at 50% maturity were 46.90 and 42.08 cm, respectively and were significantly different. This study thus increases our understanding of the reproductive biology of an important commercial and artisanal fish species in one of its major distribution areas.