ABSTRACT
Abstract Isolated sulfite oxidase deficiency (ISOD) is a devastating, neurometabolic disorder caused by mutations in the SUOX gene necessary for the final step in the sulfur-containing amino acid catabolic pathway. Patients classically present in the neonatal period with neurologic manifestations. Biochemical findings include elevated sulfocysteine, low cystine and undetectable homocysteine with normal uric acid levels. Other associated biochemical markers include elevated plasma alpha-aminoadipic semialdehyde and piperideine-6-carboxylic acid. We report a patient with classic neonatal onset ISOD (refractory seizures, hypertonicity, brain abnormalities, pathogenic SUOX mutations). Her clinical course was marked by extreme irritability, prompting the use of a low methionine and cystine diet to decrease toxic metabolites thought to be contributing to her symptoms. Biochemical markers and extreme irritability improved with dietary treatment (methionine=30mg/kg/day). She died of sepsis in early infancy, precluding long term follow-up. This case reviews the potential benefits and limitations of diet therapy in this rare disorder.
ABSTRACT
Objective To study the impact of methionine restriction (MetR) on mucosal histopathology,permeability and tight junction composition in a dextran sulfate sodium (DSS)-induced colitis model,and to explore its underlying mechanism.Methods SD rats were randomly divided into 4 groups:normal rats fed by a complete amino acid (AA group) diet,normal rats fed by MetR diet (MetR group),DSS treated rats fed by a complete amino acid (DSS + AA group) and DSS treated rats fed by MetR diet (DSS + MetR group),each group had 15 rats.Abdominal aorta blood sampling was taken at day 21 after DSS model been established to analyze blood routine examination,liver and kidney function and level of electrolyte.Morphological changes in colonic mucosa were evaluated and scored by light microscopy.Myeloperoxidase (MPO) activity was measured.The effect of MetR on mucosal permeability of colon strips was detected by Ussing chamber.Claudin2,occludin,claudin3,ZO-1 expression were quantified by Western blot.Results The early clinical manifestation in the DSS treated rats were loose stool or diarrhea,hematochezia positive and bleeding,and weight losing.HE observation showed prominent colitis in distal colon with manifestations of crypt abscess and infiltration of inflammatory cells.Although MPO activity and WBC account between the DSS + MetR and DSS + AA group did not significantly changed,treatment with MetR diet significantly decreased the extent and severity of epithelial injury of DSS + MetR group (10.55 ± 3.62 vs 15.00 ± 4.89,P =0.003).There were no significant difference in PCNA immunohistochemical result between the DSS + MetR group and DSS + AA group.Compared to the rats on AA diet,transepithelial electrical resistance(TEER) in DSS + AA group was obvious lower [(28.40 ± 6.78) Ω · cm2 vs (46.53 ± 4.03)Ω · cm2,P ＜0.05],and TEER in MetR group were obviously higher[(60.64 ± 8.40)Ω · cm2 vs (46.53 ±4.03)Ω · cm2,P ＜0.05].However,short-circuit current (Isc) in DSS + MetR group was obviously higher that of DSS + AA group [(35.01 ± 2.19) μA/cm2 vs (29.61 ± 1.19) μA/cm2,P ＜0.05].Western blot suggested that colon claudin2 expression was not found in colon epithelium of normal rats,and an obviously increase expression of claudin3 protein was found in the MetR group,compared to AA group; and an significantly increase in the abundance of claudin3 was found in the DSS + MetR group,but amount of claudin2 was decreased,compared with the DSS + MetR group.Conclusion The MetR diet has obvious therapeutic effect on ulcerative colitis model rats induced by DSS,and its mechanism may not by regnlating inflammatory cell infiltration and the way of promoting intestinal cell growth to alleviate inflammatory injury,but probably by changing the structure and function of tight junction protein and improve the intestinal mucosal barrier function,and promote the repair of damaged intestinal mucosa.