Corrigendum to: The Horton-Rogers-Lapwood problem for an inclined porous layer with permeable boundaries.

[This corrects the article DOI: 10.1098/rspa.2018.0021.].

Unstable wave-packet perturbations in an advective Cahn-Hilliard process.

A study of the perturbation dynamics in a one-dimensional advective Cahn-Hilliard system, characterized by a nonvanishing driving force, is carried out to test the stability of a uniform basic solution. The linear stability of small-amplitude perturbations is analyzed both in the case of normal Fourier modes, with a given wave number, and in the case of wave packets localized in space. The dual nature of the instability, either of convective or absolute type, is studied, revealing that the driving force creates a gap between the parametric threshold to instability of normal modes and that to instability of wave packets. When the driving force is zero, also the gap between such thresholds disappears.

Effects of an High-Fat Diet Enriched in Lard or in Fish Oil on the Hypothalamic Amp-Activated Protein Kinase and Inflammatory Mediators.

The high fat diet (HFD) rich in lard induces obesity, inflammation and oxidative stress, and the deregulation of hypothalamic nuclei plays an important role in this mechanism. One important factor involved in the food intake and inflammation is adenosine monophosphate-dependent kinase (AMPK), a serine/threonine kinase activated by phosphorylation. Omega (ω)3-polyunsaturated fatty acids (PUFA) are dietary compounds known to attenuate the obesity-related diseases, although the molecular mechanisms underlying their actions in the hypothalamus are not completely understood. We hypothesized that the beneficial effects of PUFA may be mediated by AMPK in the hypothalamus. To this aim, rats were fed a control diet (CD), or isocaloric HFD containing either fish oil (FD; rich in ω3-PUFA) or lard for 6 weeks, and the activation of AMPK, inflammatory state (IKKß, TNF-α) and oxidative stress were analyzed in the hypothalamus. In addition, we also studied serum lipid profile, homeostatic model assessment (HOMA) index, and pro-inflammatory parameters. Our results showed, at the hypothalamic level of LD-fed rats, an increase of AMPK activation, inflammation and oxidative stress, while no modifications were detected in FD-fed animals compared to CD. In addition body weight gain, serum lipid profile, pro-inflammatory parameters and insulin resistance were reduced in FD animals compared to LD. In conclusion, our data indicate that the substitution of saturated by unsaturated fatty acids in the diet has beneficial effects on modulation of hypothalamic inflammation and function in obesity, underlying, at hypothalamic level, the interaction among insulin and/or leptin resistance, AMPK activation and hyperphagia.

Nonlinear stability analysis of Darcy's flow with viscous heating.

The nonlinear stability of a rectangular porous channel saturated by a fluid is here investigated. The aspect ratio of the channel is assumed to be variable. The channel walls are considered impermeable and adiabatic except for the horizontal top which is assumed to be isothermal. The viscous dissipation is acting inside the channel as internal heat generator. A basic throughflow is imposed, and the nonlinear convective stability is investigated by means of the generalized integral transform technique. The neutral stability curve is compared with the one obtained by the linear stability analysis already present in the literature. The growth rate analysis of different unstable modes is performed. The Nusselt number is investigated for several supercritical configurations in order to better understand how the system behaves when conditions far away from neutral stability are considered. The patterns of the neutrally stable convective cells are also reported. Nonlinear simulations support the results obtained by means of the linear stability analysis, confirming that viscous dissipation alone is indeed capable of inducing mixed convection. Low Gebhart or high Péclet numbers lead to a transient overheating of the originally motionless fluid before it settles in its convective steady state.

Marangoni instability of a liquid film flow with viscous dissipation.

A linear stability analysis of a thin liquid film flowing over a plate is performed. The plate is considered as impermeable and adiabatic. The upper surface of the film is assumed to be a free boundary with a non-negligible surface tension, characterized by a Robin thermal boundary condition. The thermoconvective instability is generated by the interplay between the heating due to viscous dissipation and the temperature-dependent surface tension at the free boundary. A basic parallel flow, arbitrarily oriented, is assumed and the basic temperature profile is determined analytically. In order to investigate the linear stability of the system, the normal mode method is employed. A system of ordinary differential equations defining an eigenvalue problem is thus obtained. The case of longitudinal rolls, where the base flow velocity is parallel to the axis rolls, is solved both analytically and numerically. Other possible inclinations of the base flow are investigated by means of a numerical procedure based on combining the Runge-Kutta and the shooting methods.

Diet supplementation with donkey milk upregulates liver mitochondrial uncoupling, reduces energy efficiency and improves antioxidant and antiinflammatory defences in rats.

Dietary PUFA, mainly those of the n-3 family, are known to play essential roles in the maintenance of energy balance and in the reduction of body fat deposition through the upregulation of mitochondrial uncoupling that is the main source of reactive oxygen species. We hypothesized that rat supplementation with raw donkey's milk (DM), characterized by low-fat content and higher n3:n6 ratio, may affect energy balance, lipid metabolism, and prooxidant status as compared to animals treated with cow's milk. In the present study, the effects of drinking raw DM (for 4 weeks) on energy balance, lipid metabolism, antiinflammatory, and antioxidant/detoxifying defences was compared to that produced by rat intake of an iso-energetic amount of raw cow's milk. The hypolipidemic effect produced by DM paralleled with the enhanced mitochondrial activity/proton leakage and with the increased activity or expression of mitochondrial markers namely, carnitine palmitoyl transferase and uncoupling protein 2. The association of decreased energy efficiency with reduced proinflammatory signs (TNF-α and LPS levels) with the significant increase antioxidant (total thiols) and detoxifying enzyme activities (glutathione-S-transferase NADH quinone oxidoreductase) in DM-treated animals, indicated that beneficial effects were attributable, at least in part, to the activation of nuclear factor 2 erythroid-related factor 2 pathway.

3,5-diiodo-l-thyronine, by modulating mitochondrial functions, reverses hepatic fat accumulation in rats fed a high-fat diet.

BACKGROUND/AIMS: Mitochondrial dysfunction is central to the physiopathology of steatosis and/or non-alcoholic fatty liver disease. In this study on rats we investigated whether 3,5-diiodo-l-thyronine (T2), a biologically active iodothyronine, acting at mitochondrial level is able to reverse hepatic steatosis after its induction through a high-fat diet. METHODS: Hepatic steatosis was induced by long-term high-fat feeding of rats for six weeks which were then fed the same high-fat diet for the next 4 weeks and were simultaneously treated or not treated with T2. Histological analyses were performed on liver sections (by staining with Sudan black B). In liver mitochondria fatty acid oxidation rate, mitochondrial efficiency (by measuring proton conductance) and mitochondrial oxidative stress (by measuring H(2)O(2) release, aconitase and SOD activity) were detected. RESULTS: Stained sections showed that T2 treatment reduced hepatic fatty accumulation induced by a high-fat diet. At the mitochondrial level, the fatty acid oxidation rate and carnitine palmitoyl transferase activity were enhanced by T2 treatment. Moreover, by stimulating mitochondrial uncoupling, T2 caused less efficient utilization of fatty acid substrates and ameliorated mitochondrial oxidative stress. CONCLUSION: These data demonstrate that T2, by activating mitochondrial processes, markedly reverses hepatic steatosis in vivo.

Cold exposure differently influences mitochondrial energy efficiency in rat liver and skeletal muscle.

This study deals with mitochondrial energy efficiency in liver and skeletal muscle mitochondria in 15 days cold exposed rats. Cold exposure strongly increases the sensitivity to uncoupling by added palmitate of skeletal muscle but not liver mitochondria, while mitochondrial energy coupling in the absence of fatty acids is only slightly affected by cold in liver and skeletal muscle. In addition, uncoupling protein 3 content does not follow changes in skeletal muscle mitochondrial coupling. It is therefore concluded that skeletal muscle could play a direct thermogenic role based on fatty acid-induced mild uncoupling of mitochondrial oxidative phosphorylation.

Protective effect of alpha-tocopherol in head and neck cancer radiation-induced mucositis: a double-blind randomized trial.

BACKGROUND: the study was designed to test whether vitamin E (VE) provides oral mucosal protection in patients with irradiated cancers of the head and neck. METHODS: Fifty-four patients with cancer of the oral cavity and oropharynx were randomly assigned to rinse the oral cavity in an oil solution containing either VE or placebo before every conventional fraction of 2 Gy and again 8 to 12 hours later during the 5 to 7 weeks of radiotherapy (RT). RESULTS: Thirty-six events/167 patient-weeks (21.6%) and 54 events/161 patient-weeks (33.5%) of symptomatic mucositis were observed in VE and placebo groups, respectively (p =.038). VE reduced the risk by 36%. Subjective data at the end of the treatment revealed that VE decreased pain grades 2 to 3 during RT (3 of 28 patients vs 14 of 26 patients, p =.0001). No significant influence was detected in survival. CONCLUSION: VE decreased the incidence of symptomatic oral radio-induced mucositis in patients with cancer of the oropharynx and oral cavity.

Effect of high-fat feeding on metabolic efficiency and mitochondrial oxidative capacity in adult rats.

The changes in metabolic efficiency, body composition, and nutrient partitioning induced by high-fat feeding were evaluated in adult rats (90 d of age). The alterations in serum free triiodothyronine, insulin, and leptin levels, as well as in hepatic and skeletal muscle metabolism, were also assessed. Rats were fed either a low- or a high-fat diet for 2 weeks. Relative to the low-fat feeding, energy intake and expenditure, as well as body-energy gain, lipid gain, and energetic efficiency, were increased by the high-fat feeding. Increased serum leptin levels accompanied these variations. A positive correlation between serum leptin levels and percentage of body fat was found in the rats fed the low- or high-fat diet, with a significant divergence between the slope of the regression lines. Furthermore, a negative correlation between serum leptin level and energy intake was found in the rats fed the low-fat diet, while a positive correlation was found in the rats fed the high-fat diet. Finally, the high-fat feeding decreased the hepatic and skeletal muscle mitochondrial oxidative capacity. It is concluded that, in adult rats, a nutritional factor such as a high level of fat in the diet induces obesity, leptin resistance, and impairment of mitochondrial capacity, all phenomena typical of unrestrained aged rats.

Acetyl-L-carnitine supplementation differently influences nutrient partitioning, serum leptin concentration and skeletal muscle mitochondrial respiration in young and old rats.

Variations in energy balance, body composition, and nutrient partitioning induced by acetyl-L-carnitine (ALCAR) supplementation were studied in young (2 mo) and old (24 mo) Wistar rats. Changes in skeletal muscle metabolism as well as in serum free triiodothyronine and leptin levels were also evaluated. Rats were administered 0 (control) or 15 g/L ALCAR in their drinking water for 1 mo. ALCAR treatment significantly decreased body lipid percentage in young rats and significantly increased body protein percentage in old rats. The percentage of metabolizable energy (ME) intake stored as lipid was lower in ALCAR-treated young rats, whereas the percentage of ME intake stored as protein was greater in ALCAR-treated old rats compared with their age-matched controls. In addition, ALCAR supplementation significantly decreased serum leptin levels in old rats. Elevated skeletal muscle respiration was found in old rats treated with ALCAR, due to an increase in mitochondrial protein mass. In conclusion, ALCAR supplementation decreases efficiency of lipid deposition in young rats and increases efficiency of protein deposition in old rats. In addition, ALCAR supplementation partly reduces the leptin resistance that occurs in old rats, and improves ATP production in skeletal muscle mitochondria through an increase in mitochondrial protein content.

Biologia das metástases: o que há de novo? / Biology of metastasis: what is new?

A interpretaçäo atual do comportamento diversificado das células metastáticas, com relaçäo ao seu padräo de crescimento e sensibilidade ao tratamento, deve-se aos fenômenos de heterogeneidade. É feita uma revisäo bibliográfica dos últimos anos acerca dos mecanismos pelos quais a heterogeneidade interfere no sucesso da terapêutica e, também, sobre o rumo das pesquisas que vêm se ocupando em superar este problema.

Radioterapia experimental: avanços nos anos 80 e rumos para o futuro / Experimental radiotherapy: advances in the 80' and course for the future

A radioterapia é um dos tratamentos mais efetivos para o controle local do câncer, tendo sua eficiência prejudicada algumas vezes pela açäo antagônica causada pelas baixas concentraçöes de oxigênio ao nível do tumor. Nos anos 80 houve um impulso notável no sentido de intensificar o efeito biológico da radioterapia pelo uso de novas tecnologias, e também pela síntese de modificadores químicos da resposta a radiaçäo. Nesta revisäo, comentam-se os avanços obtidos e as implicaçöes para a próxima década

Manuseio radioterápico na síndrome de compressäo da veia cava superior

A síndrome de compressäo da veia cava superior é uma situaçäo de emergência incomum nos casos de carcinoma brônquico e linfomas, surgindo mais remotamente em doenças benignas. Um atendimento rápido e efetivo pode reverter os síntomas em poucos dias. Foram analisadas características clínicas em 29 pacientes admitidos en nosso serviço de 1981 a 1986, havendo 4 exclusöes para os estudos de respostas clínica. A dose total de radioterapia foi ao redor de 6000 cGy/6 semanas, con o emprego de altas doses iniciais ou doses convencionais. As respostas foram consideradas muito satisfatórias. Alguns pacientes receberam quimioterapia prévia ou concomitante a irradiaçäo. Näo houve vantagem do tratamento combinado nesta série. O emprego de quimioterapia é considerado de primeira escolha pela literatura no manuseio da síndrome causada pelo carcinoma avenocelular e linfomas

Radioterapia do câncer de esôfago / Radiotherapy of the esophageal cancer

O câncer de esôfago ocupa a 3ªcausa morte por neoplasia no Estado do Rio Grande do Sul na populaçäo masculina. Os autores analisam algumas características epidemiológicas e os resultados do tratamento radioterápico exclusivo em 40 pacientes tratados com Acelerador Linear de 8 MV, na dose de 6000cGy/ 6 semanas. Considerando que de uma forma geral qualquer tratamento utilizado é eminentemente paliativo, discute-se o papel da esofagectomia e a morbi-mortalidade associada. A probabilidade acumulada de sobreviver atingida com a radioterapia foi de 60,55%, 29,15% e 11,93% aos 6, 12 e 22 meses, respectivamente. Foi obtido um efeito desobstrutivo em 75% dos casos, permitindo uma deglutiçäo completamente livre ou de no mínimo 50% da capacidade normal, sem a ocorrência de efeitos colaterais significativos. Estes índices colocam a radioterapia exclusiva numa posiçäo de destque no tratamento paliativo do câncer de esôfago