An Osmotic Model of the Growing Pollen Tube

Pollen tube growth is central to the sexual reproduction of plants and is a longstanding model for cellular tip growth. For rapid tip growth, cell wall deposition and hardening must balance the rate of osmotic water uptake, and this involves the control of turgor pressure. Pressure contributes directly to both the driving force for water entry and tip expansion causing thinning of wall material. Understanding tip growth requires an analysis of the coordination of these processes and their regulation. Here we develop a quantitative physiological model which includes water entry by osmosis, the incorporation of cell wall material and the spreading of that material as a film at the tip. Parameters of the model have been determined from the literature and from measurements, by light, confocal and electron microscopy, together with results from experiments made on dye entry and plasmolysis in Lilium longiflorum. The model yields values of variables such as osmotic and turgor pressure, growth rates and wall thickness. The model and its predictive capacity were tested by comparing programmed simulations with experimental observations following perturbations of the growth medium. The model explains the role of turgor pressure and its observed constancy during oscillations; the stability of wall thickness under different conditions, without which the cell would burst; and some surprising properties such as the need for restricting osmotic permeability to a constant area near the tip, which was experimentally confirmed. To achieve both constancy of pressure and wall thickness under the range of conditions observed in steady-state growth the model reveals the need for a sensor that detects the driving potential for water entry and controls the deposition rate of wall material at the tip

Progressive skin fibrosis is associated with a decline in lung function and worse survival in patients with diffuse cutaneous systemic sclerosis in the European Scleroderma Trials and Research (EUSTAR) cohort.

Objectives To determine whether progressive skin fibrosis is associated with visceral organ progression and mortality during follow-up in patients with diffuse cutaneous systemic sclerosis (dcSSc). Methods We evaluated patients from the European Scleroderma Trials and Research database with dcSSc, baseline modified Rodnan skin score (mRSS) ≥7, valid mRSS at 12±3 months after baseline and ≥1 annual follow-up visit. Progressive skin fibrosis was defined as an increase in mRSS >5 and ≥25% from baseline to 12±3 months. Outcomes were pulmonary, cardiovascular and renal progression, and all-cause death. Associations between skin progression and outcomes were evaluated by Kaplan-Meier survival analysis and multivariable Cox regression. Results Of 1021 included patients, 78 (7.6%) had progressive skin fibrosis (skin progressors). Median follow-up was 3.4 years. Survival analyses indicated that skin progressors had a significantly higher probability of FVC decline ≥10% (53.6% vs 34.4%; p<0.001) and all-cause death (15.4% vs 7.3%; p=0.003) than non-progressors. These significant associations were also found in subgroup analyses of patients with either low baseline mRSS (≤22/51) or short disease duration (≤15 months). In multivariable analyses, skin progression within 1 year was independently associated with FVC decline ≥10% (HR 1.79, 95% CI 1.20 to 2.65) and all-cause death (HR 2.58, 95% CI 1.31 to 5.09). Conclusions Progressive skin fibrosis within 1 year is associated with decline in lung function and worse survival in dcSSc during follow-up. These results confirm mRSS as a surrogate marker in dcSSc, which will be helpful for cohort enrichment in future trials and risk stratification in clinical practice

Untreated 24-Hour Intraocular Pressure Measured by Goldmann Applanation Tonometry Compared to Nightime Supine Pressures With Perkins' Applanation Tonometry

Purpose:To use Perkins\u2019 applanation tonometry to measure supine nighttime intraocular pressures and to compare these values to sitting day and nighttime Goldmann applanation intraocular pressures. Methods:Prospective, untreated, uncontrolled, observational cohort. Qualified patients underwent an appropriate washout period of their current ocular hypotensive medications. Patients with pressures of 22 mm Hg at 10:00, in at least one eye, underwent pressure measurements over 24 hours at 10:00, 14:00, 18:00, 22:00, 02:00 and 06:00 by Goldmann applanation tonometry in a sitting position. In addition, patients had their pressures measured at 10:00, 22:00, 02:00 and 06:00 by Perkins\u2019 applanation tonometry in a supine position Results:In total, 100 patients completed the study. The mean intraocular pressures at 10:00, 22:00, 02:00 and 06:00, while sitting was 23.1\ub13.6 ,and in the supine position, 23.5\ub14.3 (P<0.001). Further, the difference in pressure was significantly different between sitting and supine groups at 3 individual time points (10:00, 22:00, 02:00, P0.006) but not at 06:00 (P=0.30). Glaucoma patients (n=35) had a mean change of 22.7\ub13.5 to 23.6\ub14.0 mmHg, while ocular hypertensives (n=65) had a mean change of 22.5\ub13.6 to 23.4\ub14.4 mmHg, moving from a sitting to a supine position (P=0.07). The mean sitting Goldmann intraocular pressures across the three diurnal time points (10:00, 14:00 and 18:00) was 23.9\ub16.2 and across the three night time points (22:00, 02:00 and 06:00) was 21.4\ub10.2(P<0.001). In contrast, the mean daytime sitting Goldmann pressures were not statistically different than nighttime supine Perkins\u2019 pressures (22.8\ub14.4,P=0.07). However, only 90% of patients were within 5.7 mmHg of the highest daytime reading for all nighttime supine and sitting pressures. Conclusions:This study suggests that by Goldmann applanation tonometry, untreated supine or sitting intraocular pressures are not higher at night than daytime sitting pressures. However, the highest daytime sitting pressures do not predict well the highest nighttime sitting or supine pressure values

Avaliação sensorial em carnes pse (mole, pàlida e exsudativa) de suínos.

O atual sistema de produção de suínos, tem levado a mudanças na composição da carcaça,caumentando consideravelmente o percentual de carne magra, ocasionando com isso modificações evidentes tanto na percepção sensorial, como bioquímica do músculo. Um dos efeitos desse processo é o aumento na ocorrência da síndrome PSE (do Inglês pale, soft, exudative). A carne PSE representa um grande problema de qualidade para a indústria de carne suína, devido às perdas econômicas que pode acarretar, principalmente por afetar os músculos de maior valor comercial. O objetivo desse estudo foi avaliar as características sensoriais da carne PSE em suínos. Em um abatedouro comercial foram avaliadas 964 carcaças por aferição de pH aos 45 minutos após o abate (pH45). Carcaças com pH45 ≤ 5,8 foram classificadas como PSE e aquelas cujo pH45 foi > 5,8 foram classificadas como normais. Foram coletadas amostras do músculo Longissimus dorsi de 13 carcaças diagnosticadas como PSE e 13 consideradas normais, após 24 horas de resfriamento. Foi realizada a avaliação sensorial dos dois tipos de carne para os seguintes parâmetros - maciez, palatabilidade e suculência - por um painel de cinco degustadores treinados, que atribuíram valores de 01 (carne extremamente dura, sem suculência e sabor extremamente desagradável) a 09 (carne extremamente macia, suculenta e saborosa). Não foram observadas diferenças significativas (P>0,05), entre os dois tipos de carne para os parâmetros avaliados. Ambas as carnes foram consideradas como macias (6,85 e 6,33, P>0,1308), com suculência abaixo da média (4,67 e 4,60, P>0,5695) e palatabilidade acima de média (6,11 e 6,33, P>0,7013), respectivamente para normais e PSE. Conclui-se que, as conhecidas alterações nas propriedades físicas sofridas pela carne PSE ao longo do processo de transformação do músculo em carne não foram perceptíveis pelo painel de degustação

Prospecção de genes diferencialmente expressos associados com a resistência de bovinos de corte ao carrapato Rhipicephalus (Boophilus) microplus.

Comissão organizadora: Grácia Maria Soares Rosinha, Alexandra Rocha de Oliveir, Rodrigo Carvalho Alva