The adaptive modulation hypothesis posits that the expression of digestive proteins should be modulated in response to intake of their respective substrates. A corollary of this hypothesis suggests that dietary flexibility and digestive plasticity should be correlated. We examined these two hypotheses in two granivorous Chilean birds (Zonotrichia capensis and Diuca diuca) that differ in dietary breadth. D. diuca is a strict granivore, whereas Z. capensis also eats insects. In field-caught birds, the activity of the intestinal dipeptidase aminopeptidase-N was positively correlated with intake of insects in Z. capensis but not in D. diuca. This is the first field documentation of modulation of intestinal enzymes by diet in birds. Intestinal maltase and sucrase activities were not correlated with seed (vs. insect) intake in either species. In the laboratory, captive birds of both species exhibited similar modulation of membrane-bound intestinal hydrolases when fed on synthetic diets of contrasting carbohydrate and protein composition. Maltase, sucrase, and aminopeptidase-N activities were significantly higher in birds fed on the carbohydrate-free than those on the carbohydrate-containing diet. Activities of the three enzymes were positively correlated. Therefore, this increase probably resulted from nonspecific increases of all enzymes resulting from intake of the carbohydrate-free diet. Principal components analysis separating the effect of diet on specific and on nonspecific modulation revealed that diet had a strong effect on nonspecific activity of intestinal enzymes in both Z. capensis and D. diuca. Diet also significantly affected aminopeptidase-N activities when the effect of diet on nonspecific modulation was removed. Birds fed on the carbohydrate-free, high-protein diet had significantly higher specific aminopeptidase-N activities than those fed on the carbohydrate-containing diet. Our results cast doubts on the notion that dietary flexibility and the plasticity of the gut's enzymes are necessarily correlated and on the general validity of the adaptive modulation hypothesis.

Adaptation, Biological↗

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[Treatment of massive spasms with synthetic ACTH].

Ten infants with infantile spasms (IS) and hypoarrhythmic EEG, received 0.5 mg i.m. of synthetic ACTH, three times a week for 2 weeks. Six of them showed complete remission of seizures and dramatic EEG changes, and 3 cases resulted in a partial response. Spasms were controlled during the first week in 5/6 cases where treatment was successful. A significant relationship was observed between treatment precocity and favourable outcome (Fisher p < 0.02). Synthetic ACTH treatment did not produce severe side effects in any patient. During follow up (X 6.2 m) relapse occurred in one case, with 5 patients maintaining the initial positive response and a normal or mildly retarded psychomotor development. The other five patients show severe psychomotor retardation and intractable spasms and/or other seizures. Future research should focus on the efficacy of other treatment schedules, equilibrating success and side effects.

Adrenocorticotropic Hormone↗

PubMedDate not supplied

[Etiologic research in massive spasms].

A systematic clinical protocol was applied in 16 infants that suffered from infantile spasms (IS) in order to identify etiologic factors. A positive family history was present in 2/16 patients and relevant perinatal or postnatal pathology in 5/16. Psychomotor retardation and other seizures anteceded IS in 10/16 and 8/16 infants respectively. Physical and neurologic examination revealed microcephalia (4/16), dysmorphic features (2/16), hypopigmented skin lesions (1/16) and pyramidal syndrome (8/16). Neuroimaging technics yielded positive findings in 9/16 patients, diffuse or localized atrophy (7/16), porencephalic cysts (3/16), periventricular calcifications (1/16), callosal agenesis (1/16). Laboratory examination allowed diagnosis of two metabolic diseases: congenital hyperlactatemia an maple syrup urine disease. Two patients were classified as cryptogenetic and fourteen as symptomatic. Within the latter an etiologic factor was identified in 12/14. This study underlines the value of etiologic search in IS, because it may contribute substantially to specific treatment and genetic counselling.

Clinical Protocols↗

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