Continuous Uniform Finite Time Stabilization of Planar Controllable Systems

Continuous homogeneous controllers are utilized in a full state feedback setting for the uniform finite time stabilization of a perturbed double integrator in the presence of uniformly decaying piecewise continuous disturbances. Semiglobal strong $\mathcal{C}^1$ Lyapunov functions are identified to establish uniform asymptotic stability of the closed-loop planar system. Uniform finite time stability is then proved by extending the homogeneity principle of discontinuous systems to the continuous case with uniformly decaying piecewise continuous nonhomogeneous disturbances. A finite upper bound on the settling time is also computed. The results extend the existing literature on homogeneity and finite time stability by both presenting uniform finite time stabilization and dealing with a broader class of nonhomogeneous disturbances for planar controllable systems while also proposing a new class of homogeneous continuous controllers

Orthotopic liver transplantation for acute and subacute hepatic failure in adults

The role of liver transplantation in 29 patients with fulminant and subacute hepatic failure due to a variety of different causes was examined by comparing the outcome and a variety of “hospitalization” variables. Transplanted patients (n = 13) were more likely to survive (p < 0.05), were younger (p < 0.05) and spent more time in the hospital (p < 0.025) than did those who were not transplanted (n = 16). Despite spending a much longer time in the hospital, transplanted patients spent less time in the intensive care unit (p < 0.05) in coma (p < 0.01) and on a respirator (p < 0.01) than did those not transplanted. Most importantly, the survival rate for transplanted patients was significantly improved (p < 0.05) as compared to those not transplanted. We conclude that liver transplantation can be applied successfully to the difficult clinical problem of fulminant and subacute hepatic failure. Copyright © 1987 American Association for the Study of Liver Disease

Endoscopic sclerotherapy compared with no specific treatment for the primary prevention of bleeding from esophageal varices. A randomized controlled multicentre trial [ISRCTN03215899]

BACKGROUND: Since esophageal variceal bleeding is associated with a high mortality rate, prevention of bleeding might be expected to result in improved survival. The first trials to evaluate prophylactic sclerotherapy found a marked beneficial effect of prophylactic treatment. These results, however, were not generally accepted because of methodological aspects and because the reported incidence of bleeding in control subjects was considered unusually high. The objective of this study was to compare endoscopic sclerotherapy (ES) with nonactive treatment for the primary prophylaxis of esophageal variceal bleeding in patients with cirrhosis. METHODS: 166 patients with esophageal varices grade II, III of IV according to Paquet's classification, with evidence of active or progressive liver disease and without prior variceal bleeding, were randomized to groups receiving ES (n = 84) or no specific treatment (n = 82). Primary end-points were incidence of bleeding and mortality; secondary end-points were complications and costs. RESULTS: During a mean follow-up of 32 months variceal bleeding occurred in 25% of the patients of the ES group and in 28% of the control group. The incidence of variceal bleeding for the ES and control group was 16% and 16% at 1 year and 33% and 29% at 3 years, respectively. The 1-year survival rate was 87% for the ES group and 84% for the control group; the 3-year survival rate was 62% for each group. In the ES group one death occurred as a direct consequence of variceal bleeding compared to 9 in the other group (p = 0.01, log-rank test). Complications were comparable for the two groups. Health care costs for patients assigned to ES were estimated to be higher. Meta-analysis of a large number of trials showed that the effect of prophylactic sclerotherapy is significantly related to the baseline bleeding risk. CONCLUSION: In the present trial, prophylactic sclerotherapy did not reduce the incidence of bleeding from varices in patients with liver cirrhosis and a low to moderate bleeding risk. Although sclerotherapy lowered mortality attributable to variceal bleeding, overall survival was not affected. The effect of prophylactic sclerotherapy seems dependent on the underlying bleeding risk. A beneficial effect can only be expected for patients with a high risk for bleeding

Adverse effects of the antimalaria drug, mefloquine: due to primary liver damage with secondary thyroid involvement?

BACKGROUND: Mefloquine is a clinically important antimalaria drug, which is often not well tolerated. We critically reviewed 516 published case reports of mefloquine adverse effects, to clarify the phenomenology of the harms associated with mefloquine, and to make recommendations for safer prescribing. PRESENTATION: We postulate that many of the adverse effects of mefloquine are a post-hepatic syndrome caused by primary liver damage. In some users we believe that symptomatic thyroid disturbance occurs, either independently or as a secondary consequence of the hepatocellular injury. The mefloquine syndrome presents in a variety of ways including headache, gastrointestinal disturbances, nervousness, fatigue, disorders of sleep, mood, memory and concentration, and occasionally frank psychosis. Previous liver or thyroid disease, and concurrent insults to the liver (such as from alcohol, dehydration, an oral contraceptive pill, recreational drugs, and other liver-damaging drugs) may be related to the development of severe or prolonged adverse reactions to mefloquine. IMPLICATIONS: We believe that people with active liver or thyroid disease should not take mefloquine, whereas those with fully resolved neuropsychiatric illness may do so safely. Mefloquine users should avoid alcohol, recreational drugs, hormonal contraception and co-medications known to cause liver damage or thyroid damage. With these caveats, we believe that mefloquine may be safely prescribed in pregnancy, and also to occupational groups who carry out safety-critical tasks. TESTING: Mefloquine's adverse effects need to be investigated through a multicentre cohort study, with small controlled studies testing specific elements of the hypothesis

Liver transplantation: indication and survival

O sucesso dos transplantes de fígado certamente seria comprometido se a avaliação pré-operatória dos pacientes não fosse realizada de forma adequada. Isto se justifica devido ao reconhecimento de que o sucesso da cirurgia depende, em princípio, do diagnóstico da doença de base, da determinação de sua extensão e do grau de repercussão sistêmica. No final das décadas de setenta a noventa os progressos da hepatologia na identificação das hepatites virais e no manejo da ascite e da síndrome hepatorrenal melhoraram sobremaneira a expectativa de vida do doente portador de doença hepática crônica. Mas, sem dúvida o transplante ortotópico do fígado (TOF) foi o espetacular avanço da hepatologia moderna. Atualmente o transplante é um tratamento eficaz das hepatopatias crônicas, e o índice de sobrevivência global aos 3 anos é ao redor de 80%. É, portanto, uma alternativa de tratamento indicada nos casos terminais, onde a mortalidade com tratamentos conservadores pode atingir até 70% ao final de 12 meses. Neste artigo, os autores comentam aspectos do TOF, relacionados à indicação e a sobrevida. _________________________________________________________________________________________ ABSTRACT: The success of liver transplantation would be certainly compromised if the pre-operative evaluation was not adequately performed. The success of the liver transplantation depends on the diagnosis of the underlying hepatic disease, the determination of its extension and the degree of systemic repercussion. In the last 30 years, the progress in hepatology, the identification of viral hepatitis and the better management of ascitis and hepatorenal syndrome have increased the life expectancy of patients with chronic liver failure. Undoubtedly, orthotopic liver transplantation represents a great advance in modern hepatology. Nowadays, liver transplantation represents a valid therapeutic option for chronic liver diseases with (and presents) a mean survival rate of about 80% in 3 years. Thus, it is an indicated treatment in situations where the conservative treatment (would) could lead to a (incur) mortality rate as high as 70% in one year. In this article the authors comment (on) various aspects of Orthotopic Liver Transplantation related to indications and survival rates

Experimental and numerical study of heat and mass transfer during contact heating of sliced potatoes

International audienceTo deal with this, kinetics of product water loss and temperature rise were recorded during contact heating of potato slices in order to examine the influence of the heating power and of the presence or not of an oil layer below the heated product. From the experimental data acquired, a 2D mathematical model based on a moving boiling-front approach was developed and validated allowing the determination of contact heat transfer coefficient values of 512.2 +/- 12.4 W m(-2).K-1 and 197.5 +/- 5.8 W m(-2).K-1 for experiments with and without oil respectively. The analysis of the simulation results showed that the overall heating of the product is limited by: (i) the evaporation of liquid water at the location of a boiling front propagating within the heated product and (ii) by the development of a dried region (crust) in the lower part of the product acting as a thermal insulating layer. It should also be noted that the determination of the contact heat transfer coefficient can become an incidental problem (especially for experiments with oil) since the thermal contact resistance is often much lower than the thermal resistance associated with conduction in the dried region of the product

Wilson's disease with severe hepatic insufficiency: beneficial effects of early administration of D-penicillamine

BACKGROUND—Wilson's disease, heralded by severe hepatic insufficiency, is a rare disorder for which emergency liver transplantation is considered to be the only effective therapy.
AIMS—To report the features of Wilson's disease with severe hepatic insufficiency in a series of 17 patients and, during the second period of the study, to assess the efficacy of a policy consisting of early administration of D-penicillamine.
PATIENTS—Seventeen consecutive patients with Wilson's disease were studied. During the first period of the study (up to 1979), none of the patients received D-penicillamine. During the second period (after 1979), all patients without encephalopathy at admission received D-penicillamine.
RESULTS—The four patients observed during the first period who did not have encephalopathy at admission and did not receive D-penicillamine progressed to encephalopathy and died. Among the 13 consecutive patients observed during the second period, two patients with encephalopathy at admission did not receive D-penicillamine and were transplanted. The 11 remaining patients all received D-penicillamine. Ten of these patients survived without the need for transplantation and returned to compensated liver disease without liver insufficiency. In one patient, liver insufficiency progressed and transplantation had to be performed.
CONCLUSIONS—In most patients with Wilson's disease heralded by severe hepatic insufficiency and without encephalopathy at admission, early administration of D-penicillamine was associated with survival without transplantation. These results suggest the importance of early diagnosis of this form of Wilson's disease before the onset of encephalopathy, and favour early administration of D-penicillamine which could avoid the need for transplantation in most cases.


Keywords: Wilson's disease; acute liver failure; liver transplantation; hepatic encephalopath