A model-based approach for the rational design of the freeze-thawing of a protein-based formulation

Proteins are unstable molecules that may be severely injured by stresses encountered during freeze-thawing. Despite this, the selection of freeze-thaw conditions is currently empirical, and this results in reduced process control. Here we propose a mathematical model that takes into account the leading causes of protein instability during freeze-thawing, i.e. cold denaturation and surface-induced unfolding, and may guide the selection of optimal operating conditions. It is observed that a high cooling rate is beneficial for molecules that are extremely sensitive to cold denaturation, while the opposite is true when ice-induced unfolding is dominant. In all cases, a fast thawing rate is observed to be beneficial. The simulation outputs are confirmed by experimental data for myoglobin and lactate dehydrogenase, suggesting that the proposed modeling approach can reproduce the main features of protein behavior during freeze-thawing. This approach can therefore guide the selection of optimal conditions for protein-based formulations that are stored in a frozen or freeze-dried state

Neuronavigation and intraoperative imaging system in orbital tumor surgery: a review of recent literature

Orbit is a small complex anatomic space that contains important structures, ocular globe, extrinsic muscles, cranial nerves, blood vessels, fat, lacrimal gland. In presence of orbital tumors it is mandatory to use a surgical approach that allows to achieve an adequate surgical field while preserving neurological function. Neuronavigation is the set of computer-assisted technologies used to guide or "navigate” the edges of the tumor to allow the surgeon during resection or biopsy. This technology started with use of CT data to get some landmarks of human anatomy defined “targets” that could be readily used in surgery. Finally, the evolution of modern neuroimaging technologies such intraoperative CT and MRI boosted the surgery accuracy. In order to identify advantages and practical use of these technologies we performed a nonsystematic review of the current literature using the keywords “orbital tumor or orbital neoplasia or orbital mass or orbital lesion” and “neuronavigation or navigation” published in last 10 years. We evaluated 29 papers and we can conclude that navigation in orbital surgery helps to reduce surgical damage while at the same time, allowing a more radical tumor resection. CT and MRI scans are complementary in diagnosing and in intraoperative navigation allow the surgeon to avoid and preserve vital structures, particularly in a complex surgical procedure without real anatomical landmarks for intraoperative orientation. Future is going towards rapid changes and the integration with intraoperative procedures is carrying on to new technologies further our contemporary bounds

Photosynthesis and biomass accumulation in carapa surinamensis (Meliaceae) in response to water stress at ambient and elevated CO2

Climate models predict an increase in atmospheric CO2 concentration and prolonged droughts in some parts of the Amazon, but the effect of elevated CO2 is still unknown. Two experiments (ambient CO2 ‒ 400 ppm and elevated CO2 ‒ 700 ppm) were conducted to assess the effect of drought (soil at 50% field capacity) on physiological parameters of Carapa. At ambient CO2 concentration, light-saturated net photosynthetic rate (PNsat) was reduced by 33.5% and stomatal conductance (gs) by 46.4% under drought, but the effect of drought on PNsat and gs was nullified at elevated CO2. Total plant biomass and leaf area production were also reduced (42‒47%) by drought. By changing leaf traits, Carapa is able to endure drought, as the consumptive use of water was reduced under drought (32‒40%). The improvement of PNsat under elevated CO2 and water stress and the leaf plasticity of Carapa broaden our understanding of the physiology of Amazonian trees. © The authors

Características foliares e trocas gasosas em arvoretas de espécies nativas da Amazônia Central

Global climate models predict changes on the length of the dry season in the Amazon which may affect tree physiology. The aims of this work were to determine the effect of the rainfall regime and fraction of sky visible (FSV) at the forest understory on leaf traits and gas exchange of ten rainforest tree species in the Central Amazon, Brazil. We also examined the relationship between specific leaf area (SLA), leaf thickness (LT), and leaf nitrogen content on photosynthetic parameters. Data were collected in January (rainy season) and August (dry season) of 2008. A diurnal pattern was observed for light saturated photosynthesis (Amax) and stomatal conductance (gs), and irrespective of species, Amax was lower in the dry season. However, no effect of the rainfall regime was observed on gs nor on the photosynthetic capacity (Apot, measured at saturating [CO2]). Apot and leaf thickness increased with FSV, the converse was true for the FSV-SLA relationship. Also, a positive relationship was observed between Apot per unit leaf area and leaf nitrogen content, and between Apot per unit mass and SLA. Although the rainfall regime only slightly affects soil moisture, photosynthetic traits seem to be responsive to rainfall-related environmental factors, which eventually lead to an effect on Amax. Finally, we report that little variation in FSV seems to affect leaf physiology (Apot) and leaf anatomy (leaf thickness)

Fluorescence characteristics and photoinhibition in saplings of manwood on clear days and under overcast conditions

High irradiance may reduce the productivity of tropical plants by exacerbating photoinhibition of photosynthesis, particularly in the case of shade-adapted plants. The aim of this study was to determine the effect of cloud cover on the fluorescence characteristics and photoinhibition on saplings of manwood (Minquartia guianensis Aubl.). Three-year-old saplings were exposed to full irradiance either on clear days (10, 45 and 90 min) or under overcast conditions (120, 180, and 420 min). Changes in the population of functional photosystem II (PSII), the initial (F o) and maximum fluorescences (F m), and the F v/F m ratio (maximum potential quantum yield of PSII) were monitored after plant exposure to full irradiance and during recovery (within 48 h) at low light intensity. Although photoinhibition of PSII (F v/F m) was determined by the number of photons reaching the leaf surface (photon fluence), cloudiness tended to reduce the photoinhibitory effect of irradiance. F o increased with fluence on cloudy days and was unaffected by irradiance on clear days, except for a sharp rise during the first 10 min of exposure to full sunlight. For a given photon fluence, F m was lower on clear days. Recovery from photoinhibition was similar in both light environments. Although photon fluence is the preponderant factor determining the extent of photoinhibition, cloudiness might alleviate the photoinhibitory effect of irradiance

Gas exchange, biomass allocation and water-use efficiency in response to elevated CO 2 and drought in andiroba (Carapa surinamensis, Meliaceae)

Prolonged droughts are predicted for some parts of the Amazon; however, it is still unclear how Amazonian trees will respond to water stress under the ongoing increase in CO 2 concentration. The aim of this study was to assess the effect of elevated CO 2 (eCO 2 ) and drought on photosynthetic rates, water-use efficiency, and biomass allocation in andiroba (Carapa surinamensis). The plants were grown in pots at ambient (400 ppm CO 2 ) and eCO 2 (700 ppm) at two water regimes, soil at 50% field capacity, FC (drought) and soil at 100% FC for 163 days. We measured light saturated photosynthesis on a mass basis (A sat-mass ), stomatal conductance to CO 2 on a mass basis (g sCO2-mass ), whole-plant water-use efficiency (WUE P ), biomass accumulation, specific leaf area (SLA) and total leaf area. At eCO 2 , A sat-mass increased 28% in well-watered plants and 93% under drought, whereas g sCO2-mass declined 39% in well-watered plants at eCO 2 , with no effect of drought on g sCO2-mass at eCO 2 . The total biomass gain improved 73% at eCO 2 and over CO 2 levels it was reduced (54%) by drought. WUE P improved (188%) at eCO 2 in well-watered plants and 262% under drought. SLA declined 23% at eCO 2 , but the effect of drought on SLA was null. On the contrary, total leaf area was greatly reduced (67%) by drought, but it was not affected by eCO 2 . The large increase in total biomass and the substantial improvement in WUE P under eCO 2 , and the sharp decline in leaf area under water stress widen our knowledge on the physiology of this important species for the forest management of large areas in the Amazon region. © SISEF

Crescimento e eficiência fotossintética de uso do nitrogênio e fósforo em espécies florestais da amazônia na fase juvenil

In the Amazon Rainforest, photosynthesis and tree growth may be limited by the availability of nutrient. Thus, the objectives of this study were to determine the effect of leaf N and P content on photosynthesis, and to assess plant growth in response to understory light in ten tree species in Central Amazonia. Data were collected in January 2008. The photosynthetic capacity (Apot) of leaves positively increased with foliar N and P content, but it was only responsive to P use efficiency. The contents of N and P increased as understory irradiance increased. In addition, we found a positive relationship between N content and the N/P ratio. On the contrary, the relationship between P content and the N/P ratio was negative. Specific leaf area was negatively correlated with N and P. N use efficiency declined with increases with the N/P ratio, but the N/P ratio had no significant effect on P use efficiency. Growth in diameter increased with understory light. In conclusion, saplings were highly sensitive to variations in light intensity, and P was used with high efficiency in studied species