This study suggests that supplementation with FA during long-term MTX treatment reduces the efficacy of MTX in the control of psoriasis. Due to the relatively small sample size and short duration of this study, no conclusions can be drawn regarding the possibility that FA may reduce the side-effects of MTX.

Controversy continues regarding the optimal composition of glucose electrolyte oral rehydration solutions for the treatment of acute diarrhoea. Four perfusion models (normal human jejunum, normal rat small intestine, cholera toxin treated secreting rat small intestine and rotavirus infected rat small intestine) have been developed and used to compare the efficacy of a hypotonic oral rehydration solution with standard United Kingdom British National formulary and developing world oral rehydration solutions (WHO). Despite obvious physiological and pathophysiological differences between these models there was general congruence in the water and solute absorption profiles of the different oral rehydration solutions. Hypotonic oral rehydration solution promoted significantly greater water absorption than other oral rehydration solutions in all rat models (p

Rotavirus infection is the most common cause of acute diarrhoea in children worldwide. The structural and functional consequences of mammalian rotavirus infection in the small intestine have been incompletely studied and the mechanism of enterocyte damage poorly defined. This The pathophysiology of rotavirus diarrhoea, has been studied only in neonatal pigs20-21 and mice.22 The neonatal pig model has been used for both in vivo21 and in vitro20 studies.Rotavirus infected neonatal mouse intestine has been studied in vitro using isolated intestinal segments without an intact blood and nerve supply22 and thus the pathophysiological relevance of this model might be questioned.Recently, a group B rotavirus has been reported to cause symptomatic diarrhoea in neonatal rats23 and a similar virus can cause diarrhoea in humans.24 We have infected neonatal rats with group B rat rotavirus and related the clinical course of diarrhoea to virus excretion in faeces, and to structural and functional abnormalities in the small intestine. This is the first systematic characterisation of this rotavirus infection in neonatal rats, which we consider will prove to be an excellent model for studying pathogenesis of human rotavirus infection. Methods ANIMALSNeonatal rats (Bantin & Kingham Ltd, Aldbrough Hill, UK) were obtained at the age of 5 days. For the three days before inoculation, they were kept with their mother and allowed to suckle ad libitum. At the time of inoculation each animal was about 6 cm long and weighed 12-15 g. At least six to eight animals were studied in each group at each time point.

Abstract

In summary, the pathogenesis of many gut virus infections remains uncertain. However, human and animal studies indicate that the majority of gut viruses infect villous enterocytes. Viruses appear to have different affinities for enterocytes at different sites on the villus. Infection of enterocytes leads to cell death, extrusion into the lumen, and villous atrophy when the rate of cell production in the crypts cannot keep pace with the rate of enterocyte loss. This results in a reduced surface area as well as impairment of digestive and absorptive functions. This may also result in a net secretory state. All these changes, along with others such as reduced enzymatic activity and reduced epithelial integrity, may contribute to the induction of an acute but transient malabsorptive diarrhoea which may persist until the digestive/absorptive functions of the enterocyte are restored. However, if colonic compensation is sufficient to handle the increased fluid load, diarrhoea may not be evident. The roles of villous ischaemia, altered countercurrent exchanger of altered immune responses still remain uncertain and require further investigation.