Safety and adequacy of an optimized formula for pediatric patients with cow's milk-sensitive enteropathy

AIM

Infants and children with cow's milk-sensitive enteropathy are treated with extensively hydrolyzed formulas. A formula (New Alfaré) was developed by a protein hydrolysis method that yields an amino acid profile that more closely resembles human milk compared to previous formulas, and contains nucleotides.

METHODS

The current study was a prospective, open trial aimed at evaluating the safety and nutritional adequacy of this formula for pediatric patients with clinical indications for the enteral use of semi-elemental diet. Safety was measured as normal growth based on Euro-growth standards for body mass index (BMI)-for-age z-scores, and nutritional adequacy was evaluated based on measurements of blood parameters. Forty-seven patients <32 months old, having a gestational age of ≥ 26 weeks, and weighing ≥ 1,500 g were enrolled, and fed with New Alfaré for four weeks. Weight, length and blood parameters were measured at the beginning and end of the study. Signs of tolerance to the formula (amount of formula intake, gastrointestinal symptoms and stool characteristics) were recorded daily by the parents. Twenty-five patients completed the study with all measurements.

RESULTS

There was a significant increase in the mean BMI-for-age z-score (P<0.05) and albumin concentration (P<0.01) after four weeks. Mean plasma threonine concentration decreased significantly (P=0.01) and the mean tryptophan concentration tended to increase by the end of the study (P=0.06). No adverse events related to the study formula were reported.

CONCLUSION

These results show that New Alfaré is safe and nutritionally adequate for pediatric patients with cow's milk-sensitive enteropathy.

Protein kinase C regulates alpha(2A/D)-adrenoceptor constitutive activity

We investigated a possible role for protein kinases in the constitutive activity of alpha(2A/D) adrenoceptors in membranes from transfected PC12 cells, using a [35S]GTPgammaS binding assay. After treatment of intact cells with various protein kinase inhibitors, constitutive activity was assessed by the reduction in basal GTP binding caused by the inverse agonist rauwolscine (RAU). Inhibitors of protein kinase C (PKC) caused the loss of RAU-sensitive GTP binding, while inhibitors of other protein kinases were ineffective. Anti-G(alpha) antibody treatments showed that constitutive alpha(2A/D)-receptor activity is directed toward different G proteins than agonist-stimulated activity. T373A mutant receptors exhibited increased constitutive activity, including a component that was insensitive to PKC inhibition. Since T373 is located within a putative G(i/o) activator sequence, these results suggest that PKC-dependent phosphorylation of T373 increases alpha(2A/D)-adrenergic receptor constitutive activity and causes a switch in G protein preference.

The effects of sarin-like and soman-like organophosphorus agents on MAPK and JNK in rat brains

One sarin-like and one soman-like organophosphorus agent [bis(isopropyl methyl)phosphonate, BIMP and bis(pinacolyl methyl)phosphonate, BPMP] were injected intravenously (iv) in rats. An increase in the tyrosine phosphorylation of several proteins in the cytosol fraction of the brain was observed. Activation of c-Jun N-terminal kinase (JNK) and slight activation of mitogen-activated protein kinase (MAPK) in the cytosol were also observed. The activation of these enzymes may be related to the high toxicity of these nerve agents.

Habutobin recognizes Thr(7) in the sequence of fibrinopeptide A of rabbit fibrinogen

Habutobin, a thrombin-like enzyme from Trimeresurus flavoviridis venom, cleaves only the Arg(16)-Gly(17) bond in the rabbit Aalpha chain and releases fibrinopeptide A (FPA). To investigate the role of amino acid residues in the rabbit FPA sequence upon habutobin action, we examined the inhibitory effects of FPA and peptides containing partial sequences of FPA on the habutobin action. Fibrinopeptides from rabbit, human, bovine and dog were isolated and rabbit FPA was fragmented using dilute HCl. Rabbit FPA inhibited the action of habutobin although FPA from human, bovine and dog did not. Among the fragments of rabbit FPA, a heptapeptide Aalpha 3-9, the N-terminal region of rabbit FPA, competitively inhibited the release of FPA by habutobin, whereas the C-terminal hexapeptide of FPA (Aalpha 11-16) exerted no effect on the habutobin action. Synthetic tripeptides Ser-Thr-Phe corresponding to Aalpha 6-8 and Ala-Thr-Phe also inhibited the habutobin action, but Ser-Asp-Phe and Ala-Thr-Gly did not. It is concluded that habutobin would recognize the region around Thr(7)-Phe(8) in the sequence of rabbit FPA (Aalpha 1-16) prior to the cleavage of the Arg(16)-Gly(17) bond.

Interaction between calcium and zinc on L-threonine absorption in rabbit jejunum

The essential minerals calcium and zinc serve unique functions in higher organisms, and it is well recognized that homeostatic mechanisms are involved in regulating their metabolism. However, it has been reported that zinc, at higher concentrations (1 mM), inhibits intestinal absorption of sugars and amino acids. The aim of the present work was to determine whether the inhibitory effect on L-threonine absorption across the rabbit jejunum could be modified by calcium. In media with Ca2+, zinc significantly reduced L-threonine absorption. In Ca(2+)-free media, where calcium chloride was omitted and replaced isotonically with choline chloride, the amino acid transport was not modified by zinc, but when calcium chloride was replaced isotonically with magnesium chloride, the inhibition was observed. Verapamil (blocking mainly Ca2+ transport) did not modify the inhibitory effect of zinc on L-threonine transport. When A23187 (Ca(2+)-specific ionophore) was added in media with and without Ca2+, zinc produced no change in L-threonine transport. These results suggest that calcium and zinc could have an affinity with the same chemical groups of the enterocyte membrane, which would be related to the intestinal absorption of amino acids.

Inhibition of proteasome activities and subunit-specific amino-terminal threonine modification by lactacystin

Lactacystin is a Streptomyces metabolite that inhibits cell cycle progression and induces neurite outgrowth in a murine neuroblastoma cell line. Tritium-labeled lactacystin was used to identify the 20S proteasome as its specific cellular target. Three distinct peptidase activities of this enzyme complex (trypsin-like, chymotrypsin-like, and peptidylglutamyl-peptide hydrolyzing activities) were inhibited by lactacystin, the first two irreversibly and all at different rates. None of five other proteases were inhibited, and the ability of lactacystin analogs to inhibit cell cycle progression and induce neurite outgrowth correlated with their ability to inhibit the proteasome. Lactacystin appears to modify covalently the highly conserved amino-terminal threonine of the mammalian proteasome subunit X (also called MB1), a close homolog of the LMP7 proteasome subunit encoded by the major histocompatibility complex. This threonine residue may therefore have a catalytic role, and subunit X/MB1 may be a core component of an amino-terminal-threonine protease activity of the proteasome.

Insulin regulates serine/threonine phosphorylation in activated human B lymphocytes

Activation of either dense tonsilar B lymphocytes or the B lymphoblastoid cell line T5-1 with Staphylococcus aureus, Cowan strain I, induced surface expression of insulin receptors. Addition of insulin to these activated cells resulted in subsequent phosphorylation of the B cell surface protein CD20, the functions to regulate B cell activation. The cytoplasmic domains of CD20 contain multiple serine and threonine residues, of which at least two are followed by acidic sequences typical of substrate sites favored by casein kinase II. Tryptic mapping of CD20 isolated from intact cells treated with insulin showed increased phosphorylation on peptides having similar migration to those phosphorylated by casein kinase II in vitro. Treatment of tonsilar B cells or T5-1 cells with phorbol esters or in vitro phosphorylation by purified protein kinase C did not result in phosphorylation of peptides phosphorylated by casein kinase II, suggesting that protein kinase C is not directly involved in CD20 phosphorylation in the response to insulin. Phosphorylation of CD20 cannot be triggered by insulin in resting B cells, as the insulin receptor is expressed only after entry into the G1 phase of the cell cycle. Thus, distinct regulation of activation pathways are available to resting as opposed to activated B lymphocytes.