Liquid Biopsy in Head and Neck Cancer: Its Present State and Future Role in Africa.

The rising mortality and morbidity rate of head and neck cancer (HNC) in Africa has been attributed to factors such as the poor state of health infrastructures, genetics, and late presentation resulting in the delayed diagnosis of these tumors. If well harnessed, emerging molecular and omics diagnostic technologies such as liquid biopsy can potentially play a major role in optimizing the management of HNC in Africa. However, to successfully apply liquid biopsy technology in the management of HNC in Africa, factors such as genetic, socioeconomic, environmental, and cultural acceptability of the technology must be given due consideration. This review outlines the role of circulating molecules such as tumor cells, tumor DNA, tumor RNA, proteins, and exosomes, in liquid biopsy technology for the management of HNC with a focus on studies conducted in Africa. The present state and the potential opportunities for the future use of liquid biopsy technology in the effective management of HNC in resource-limited settings such as Africa is further discussed.

Growth of algal biomass in laboratory and in large-scale algal photobioreactors in the temperate climate of western Germany.

Growth of Chlorella vulgaris was characterized as a function of irradiance in a laboratory turbidostat (1L) and compared to batch growth in sunlit modules (5-25L) of the commercial NOVAgreen photobioreactor. The effects of variable sunlight and culture density were deconvoluted by a mathematical model. The analysis showed that algal growth was light-limited due to shading by external construction elements and due to light attenuation within the algal bags. The model was also used to predict maximum biomass productivity. The manipulative experiments and the model predictions were confronted with data from a production season of three large-scale photobioreactors: NOVAgreen (<36,000L), IGV (2,500-3,500L), and Phytolutions (28,000L). The analysis confirmed light-limitation in all three photobioreactors. An additional limitation of the biomass productivity was caused by the nitrogen starvation that was used to induce lipid accumulation. Reduction of shading and separation of biomass and lipid production are proposed for future optimization.

Tracheal resection for laryngotracheal stenosis: A retrospective analysis.

Laryngotracheal stenosis develops when scar tissue forms in the trachea and, rarely, in the larynx itself. Symptoms depend on the degree of airway obstruction and can range from asymptomatic to upper airway obstruction severe enough to cause death. We report on 21 patients who underwent tracheal resection for severe stenosis. Resection remains a good option in this situation, and there is a minimal need for specialised postoperative care or intensive care unit admission in the majority of cases.

Microalgal biomass production: challenges and realities.

The maximum quantum yield (Φ (max)), calculated from the maximum chlorophyll a specific photosynthetic rate divided by the quantum absorption per unit chlorophyll a, is 8 photons or 0.125 mol C per mol Quanta light energy. For the average solar radiation that reaches the earth's surface this relates to a photosynthetic yield of 1.79 g(dw) m(-2) day(-1) per percentage photosynthetic efficiency and it could be doubled for sunny, dry and hot areas. Many factors determine volumetric yields of mass algal cultures and it is not simply a question of extrapolating controlled laboratory rates to large scale outdoor production systems. This is an obvious mistake many algal biotechnology start-up companies make. Closed photobioreactors should be able to outperform open raceway pond cultures because of the synergistic enhancement of a reduced boundary layer and short light/dark fluctuations at high turbulences. However, this has not been shown on any large scale and to date the industrial norm for very large production systems is open raceway production ponds. Microalgal biomass production offers real opportunities for addressing issues such as CO(2) sequestration, biofuel production and wastewater treatment, and it should be the preferred research emphasis.

Ameliorative role of nitric oxide on H2O2 toxicity to a chlorophycean alga Scenedesmus obliquus.

A concentration-dependent toxicity of hydrogen peroxide (H(2)O(2)) was observed on growth yield, chlorophyll a content and chlorophyll fluorescence characteristics of the green microalga Scenedesmus obliquus under laboratory batch culture conditions. The addition of sodium nitroprusside, a nitric oxide (NO) donor, in combination with H(2)O(2) prevented chlorophyll losses, and the inhibition level of growth yield, maximum quantum yield of photosystem II (PSII) and the light-adapted quantum yield of PSII were significantly reduced. The antioxidant compounds, penicillamine and thiourea also reduced the damage caused by H(2)O(2) exposure. The protective actions of sodium nitroprusside were, however, arrested in cultures where sodium nitroprusside was supplemented in combination with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), a specific scavenger of NO. The NO(3)(-)-grown Scenedesmus depicted less sensitivity to H(2)O(2) toxicity with respect to the quantum yields of PSII as compared to its NH(4)(1)-grown counterpart. The role of NO in providing protection against H(2)O(2) toxicity to the processes under study was discussed.