Influence of chronic lactulose ingestion on the colonic metabolism of lactulose in man (an in vivo study).

The effects of a chronic load of nonabsorbable sugars on intracolonic bacterial metabolism of carbohydrates and on H2 breath excretion are disputed. However, most of the discussion relies on indirect evidence or on results of in vitro studies. Thus, we attempted to assess directly and in vivo the effects on intracolonic metabolism of lactulose of a chronic oral load of this nonabsorbable disaccharide. 20 g of lactulose was given orally twice daily during 8 d to eight normal volunteers. In all, breath H2 concentration was measured on days 1 and 8 after ingestion of the morning lactulose dose. In four subjects, stools were collected during 2 d at the beginning and at the end of the lactulose maintenance period to measure fecal pH and daily outputs of carbohydrates and beta-galactosidase. The four other subjects were intubated on days 1 and 8 to measure the pH and the concentrations of carbohydrates, lactic acid, and volatile fatty acids (VFA) in the distal ileum and cecal contents. Moreover, 14C-lactulose was added to cold lactulose and 14CO2 breath outputs determined. Pulmonary H2 excretion fell from day 1 to day 8 (P less than 0.05), whereas 14CO2 excretion increased (P less than 0.01). Fecal water pH, lactic acid, and VFA concentrations did not vary between the two stool collection periods. 24-h fecal weight, fecal water, and carbohydrate outputs showed a trend to decrease between days 1 and 2 and days 7-8, whereas beta-galactosidase activity rose markedly (P less than 0.01). No significant variations were observed for all parameters measured in ileal fluid. In the cecum, areas under the concentration curves decreased from day 1 to day 8 for lactulose, galactose, and fructose (P less than 0.01), while an increase was found for lactic acid (P less than 0.001), acetic acid (P less than 0.0001), and total VFA (P less than 0.001). Cecal fluid pH dropped faster (P less than 0.05) and to a lower level (P less than 0.05) on day 8 than on day 1. These data clearly show that a chronic load of a nonabsorbable sugar induces changes in colonic bacterial metabolic pathways resulting in a better efficiency of the flora to digest the carbohydrate.

[Comparison of the implantation and metabolic activity of human and rat fecal flora administered to axenic rats]. / Comparaison de l'implantation et de l'activité métabolique d'une flore fécale de rat et d'une flore fécale humaine inoculées chez le rat axénique.

Gnotobiotic rodents are increasingly used as a model for studying in vivo the characteristics of human colonic flora. However, the value of this model has been poorly assessed. In this study fecal bacterial flora provided either by a conventional rat (group RFR) or by man (group RFH) was administered orally to two groups of 6 germ-free rats. One month later, quantitative bacteriological analyses of feces revealed that bacterial populations were close to those of donors in both groups. The metabolic activity of the genuine flora was further compared in groups RFR and RFH with that of the implanted flora: a) concentrations of each fecal volatile fatty acid and of fecal bile acids were similar in conventional and RFR rats as well as the percentage of transformation of cholesterol into coprostanol (48 p. 100 and 54 +/- 5 p. 100 respectively; m +/- SD); b) similar concentrations of fecal volatile fatty acids were obtained from the human donor and RFH rats. Alpha, beta and omega muricholic acids absent in human donor's feces were found in RFH feces. Cholesterol transformation was lower in RFH rats (48 +/- 9 p. 100) than in man (85 p. 100); c) a single dose of lactulose (3 g/kg) increased breath hydrogen excretion in man but not in conventional or in RFR rats and RFH. Chronic lactulose ingestion (3 g/kg d.i.b. for 8 days) had no effect in conventional or RFR rats. Hydrogen excretion was decreased in man, whereas it was significantly increased in RFH rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Aqueous solubilisation of vitamin D3 in normal man.

Jejunal aqueous solubilisation of vitamin D3 was assessed in eight normal subjects, after ingestion of a standard liquid test meal. Percentages and total concentrations of vitamin D3 in the aqueous phase were significantly higher in the first post-prandial 30 minutes than during the following two hours, as were bile salts, total lipids, and free fatty acids. As shown by partial correlation analysis, a statistically significant relationship was found between aqueous concentrations of free fatty acids and of vitamin D3 in the jejunal content during all the 2 1/2 hours of the study. From these data it is concluded that, in healthy man, vitamin D3 is solubilised in vivo in mixed micelles only, and is governed in the aqueous phase.

Bovine lactoferrin induces both mucosal and systemic immune response in mice.

Lactoferrin (Lf) is a milk iron-binding glycoprotein that plays a role in iron transport and acts as both a bacteriostatic and a growth modulating agent. The aim of this study was to investigate the nature of immune responses induced by repeated oral administration of bovine milk Lf in mice. Groups of ten female BALB/c mice were fed daily for 4 weeks with two doses of protein antigen: a low (0.05 mg/g body weight per d) or high (1 mg/g body weight per d) dose of Lf, or water as a control. A fourth group was immunized intramuscularly with 0.01 mg Lf in complete Freund's adjuvant. Anti-Lf IgA and IgG were detected in the intestinal fluid and serum of mice given Lf. Total immunoglobulins were higher in the intestinal fluid in Lf groups than in the control group. No difference could be detected in the serum. IgA and IgG secretion was enhanced in Peyer's patches and spleen from Lf-fed mice, in comparison with controls. [3H]thymidine uptake into Peyer's patch and spleen cells from both control and Lf-fed mice was enhanced by 75 micrograms Lf/ml in vitro, but Lf groups had a greater proliferation rate than the control group. These findings suggested that Lf could act as an immunostimulating factor on the mucosal immune system and that activation of the mucosal immune system is dependent on the ability of Lf to bind to the intestinal mucosa.

In vitro effects of tetrodotoxin and hexamethonium on electrolyte transport in rabbit ileum treated with cholera toxin.

To determine if there was a role for the submucosal nerves in cholera toxin (CT)-induced secretion, we studied the effects of serosal addition of two neurotoxins, the nerve conduction blocking agent, tetrodotoxin (TTX), and the nicotinic ganglionic blocking agent, hexamethonium (HXM), on electrolyte secretion in control isolated rabbit ileum and in that stimulated by CT. 1). In the absence of CT, the short circuit current (Isc) decreased after TTX (10(-7) M) (P less than 0.01) and was unaltered by HXM (10(-5) M). In the presence of CT, Isc increased but was not modified by 10(-7) M TTX or 10(-5) M HXM. 2) In control tissues the mean isotopic Na+ and Cl- fluxes were not significantly altered by TTX addition. Cl- absorption alone was significantly reduced by HXM (delta JCl- = 1.95 +/- 0.81 microEq.hr-1.cm-2; P less than 0.02). After stimulation with CT, TTX significantly inhibited Na+ and Cl- secretion (delta JNa+ = 2.15 +/- 0.61 and delta JCl- = 2.15 +/- 0.76 microEq.hr-1.cm-2; P less than 0.01). Similarly, HXM significantly inhibited CT-stimulated Na+ and Cl- secretion (delta JNa+ = 1.73 +/- 0.70 and delta JCl- = 1.46 +/- 0.62 microEq.hr-1.cm-2; P less than 0.02). 3) In TTX and HXM treated tissues there was no difference in the increase in Isc caused by cAMP (2 x 10(-3) M), calcium ionophore A 23187 (4 x 10(-6) M) and glucose (10(-3) M) compared to the untreated tissues in the presence or absence of CT.(ABSTRACT TRUNCATED AT 250 WORDS)

Luminal antisecretory effects of a beta-casomorphin analogue on rabbit ileum treated with cholera toxin.

Because the physiologic significance of the presence of the opioid peptides beta-casomorphins (beta-CMs) in enzymatic digestion of milk proteins is still undetermined, the effect of the nonmetabolized beta-CM analogue beta-[DAla2,4,Tyr5]CM-5-NH2 on water and electrolyte movements was studied in vivo and in vitro in rabbit ileum untreated or treated with cholera toxin (CT). When this analogue was introduced in vivo at a concentration of 10(-3) M into the lumen of rabbit ileal loops, it significantly stimulated net water absorption in untreated loops and reduced net water secretion in CT-treated loops. In vitro addition of this analogue (10(-4) M) to the serosal compartment of untreated ileum in an Ussing chamber reduced Isc (delta Isc = 0.44 +/- 0.05 muEq.h-1/cm2) and stimulated net Na and Cl absorption to the same extent. In CT-treated ileum, both serosal (10(-4) M) and mucosal (5.10(-4) M) addition of the analogue did not further modify the rise in Isc caused by CT but also stimulated net Na and Cl absorption. On the mucosal side, the effect of the analogue was accompanied by its transfer from the luminal to the blood side of the tissue. The transferred analogue was intact as shown by HPLC (Jm----s = 2.4 +/- 0.8 nmol.h-1/cm2). These results demonstrated that the beta-CM analogue stimulates intestinal absorption of electrolytes in rabbit ileum both in the basal state and after its stimulation by CT.(ABSTRACT TRUNCATED AT 250 WORDS)

[Intestinal malabsorption of starch and gas production in the colon]. / Malabsorption intestinale de l'amidon et production gazeuse colique.

The amount of dietary starch released in the colon, its excretion in the stools, the hydrogen and methane resulting from its fermentation, were measured in six healthy volunteers, ingesting two diets, rich and low in starch (100 and 300 grams). Regardless of the diet, approximately 5% of the ingested starch was malabsorbed in the small bowel and completely metabolized in the colon. While the amount of malabsorbed starch was 2.5 times higher with 300 g than with 100 g, the volumes of hydrogen exhaled were not different. This suggests that the responsibility of alimentary substrates in the production of colic gas is overestimated.

Starch malabsorption and breath gas excretion in healthy humans consuming low- and high-starch diets.

Dietary starch delivery to the colon and excretion in stools and the ability of unabsorbed carbohydrates to promote hydrogen and methane release in breath were evaluated in 6 volunteers during two 8-day periods on starch diets of 100 and 300 g, respectively. Significantly less starch was recovered from the terminal ileum by aspiration per 24 h during the low-starch period (4.1 +/- 0.3 vs. 9.5 +/- 1.1 g, mean +/- SEM, p less than 0.01). Unabsorbed glucose tended to rise during the high-starch period (2.7 +/- 0.8 vs. 1.1 +/- 0.3 g). Fecal outputs of starch, glucose, volatile fatty acids, and lactic acid were not significantly different during the two periods. Daily breath hydrogen excretion was unchanged (181.2 +/- 22.7 vs. 193.7 +/- 19.8 ml for the low- and high-starch periods, respectively), whereas breath methane excretion increased markedly in the three methane producers during the high-starch period (217.2 +/- 80.9 vs. 32.4 +/- 7.3 ml). Starch malabsorption in the healthy small intestine was moderate even with a high-starch diet and less than that previously estimated by indirect methods. Unabsorbed starch catabolism by the colonic flora does not seem to explain most of the breath hydrogen excretion.

Synthesis and evaluation of 4-amino-substituted 7-methoxy (and 7-hydroxy)- 11-methyl (and 5,11-dimethyl)-10H-pyrido [2,3-b] carbazoles and 4-amino- substituted 11-methyl (and 5,11-dimethyl)-10H-pyrido[3',4':4,5] pyrrolo [3,2-g] quinolines, two new series related to antitumor ellipticine derivatives.

2-Acetyl-4-chloro-3-lithiopyridine ethylene glycol ketal (6b) was reacted with 3-formyl-5-methoxy-1-methyl-indole (9) and 3-formyl-1-methyl-1H-pyrrolo [3,2-c] pyridine (12), giving the corresponding expected alcohols. Reduction of these intermediates with triethylsilane trifluoroacetic acid and subsequent cyclodehydration then led to 4-chloro-7-methoxy-10,11-dimethyl-10H-pyrido [2,3-b] carbazole (8a) and the corresponding 7-aza-analog (8b). The synthesis of 4-chloro-11-methyl (and 5,11-dimethyl)-10-unsubstituted derivatives of these two series was performed through an independent pathway, involving condensation of conveniently substituted 2-amino carbazoles (17) and 7-amino-5H-pyrido [4,3-b] indoles (18) with 5-(ethoxymethylene)-2,2-dimethyl-1,3-dioxane-4,6-dione, thermal cyclization of the resulting compounds with concomitant decarboxylation to the corresponding tetracyclic fused-4-quinolone systems and final chlorination with phosphorus oxychloride. Nucleophilic substitution of various 4-chloro derivatives was then easily performed in an excess of the required dialkylamino alkylamines at reflux and 4-amino substituted-7-hydroxy-10H- pyrido [2,3-b] carbazoles (25d-e) were obtained from 7-methoxy precursors (25a-b), by demethylation with boron tribromide in methylene chloride at -65 degrees C or with boiling 47% hydrobromic acid. Cytotoxicity determination of all new aminosubstituted derivatives and in vivo antitumor evaluation of the most active compounds clearly show that these two series of ellipticine analogs closely related to highly active products are devoid of antitumor properties in two experimental models shown to be sensitive to ellipticines. The place of the pyridinic nitrogen atom in these series has thus been demonstrated to play a crucial role in antitumor activity.

Relation between chloride secretion and intracellular cyclic adenosine monophosphate in a cloned human intestinal cell line HT-29 cl 19A.

The relation between the intracellular cyclic adenosine monophosphate (cAMP) content and the electrogenic chloride secretion induced by cholera toxin was studied in secretory HT-29 cl 19A cell monolayers. Cells were treated by the mucosal addition of cholera toxin (5 micrograms/ml) for 10, 45, or 90 minutes in Ussing chambers. After 10 minutes, the mean (SEM) intracellular cAMP content (3.2 (0.2) pmol/mg protein) and short circuit current (Isc) (1.9 (0.3) microA.cm-2) did not differ significantly from the corresponding basal values. At 45 minutes, a significant increase in the Isc (22.2 (5.7) microA.cm-2) was accompanied by a significant elevation in cAMP (10(1.7) pmol/mgh protein). At 90 minutes, when the stimulated Isc plateaued (35.2 (5.2) microA.cm-2), the cAMP value (99.2 (23.8) pmol/mg protein) increased further. The protein kinase C (PKC) activity of the cells was not affected by cholera toxin. Treatment of cell monolayers by different concentrations of DbcAMP (10(5), 5 x 10(-5), 10(-3) M) showed that the minimal concentration of DbcAMP (serosal) which significantly increased the Isc (delta 4.5 microA.cm-2) was 10(-4) M, and that this was accompanied by an increase in cAMP of delta 6.7 pmol/mg protein: Compared with DbcAMP, cholera toxin stimulated the Isc (at 45 minutes) to a much higher degree with a comparable elevation of cAMP. It is concluded that in cl 19A cells there is a threshold value of increase in intracellular cAMP that induces chloride secretion. Cholera toxin stimulated chloride secretion can be explained predominantly by an increase in intracellular cAMP that is unrelated to PKC activity.

Microsphere entrapped bee-venom phospholipase A2 retains specific IgE binding capacity: a possible use for oral specific immunotherapy.

The only specific treatments of allergy are long and exacting desensitization by subcutaneous injections of the allergens. While oral administration of allergens could greatly facilitate these treatments, effective delivery systems are needed to prevent allergen degradation in the gastrointestinal tract and to enable their uptake by Peyer's patches. The potential for bee-venom phospholipase A2 (PLA2) to be used in such oral immunotherapy was tested. For this purpose, PLA2 potential alterations were analysed when encapsulated into poly(D,L-lactide-co-glycolide) microspheres by double emulsion solvent evaporation. It was shown that microencapsulation had only limited effects on the integrity of the entrapped PLA2, which retained its fully specific murine IgE binding capacity. Thus, PLA2 loaded microspheres could represent a potential delivery system for bee venom allergy-specific oral immunotherapy.

[Ludo Van Bogaert's cerebro-tendinous xanthomatosis. Apropos of 2 cases]. / Xanthomatose cérébro-tendineuse de Ludo Van Bogaert. A propos de deux observations.

The authors report of two familial cases of Ludo Van Boggert cerebro-tendinous xanthomatosis. Biochemical studies carried out in one of the patients confirmed the work of Salen indicating that the disorder is due to an enzyme problem in the hepatic synthesis of primary bile acids from cholesterol (fault in the production and cholic and chenodesoxycholic acid an an increase in the synthesis of cholestanol).

Emergence of Na+-glucose cotransport in an epithelial secretory cell line sensitive to cholera toxin.

Epithelial properties and effects of cholera toxin (CT) and glucose were investigated in human rectal tumor cell line HRT-18. Addition of 10(-3) M dibutyryl adenosine 3',5'-cyclic monophosphate (DbcAMP), 10(-8) M vasoactive intestinal peptide, 10(-5) M epinephrine, and 10(-5) M forskolin to the serosal side and of 3.5 micrograms/ml CT to the mucosal side and of 2 micrograms/ml A23187 to both the serosal and mucosal sides raised short-circuit current (Isc). This rise was reversed by serosal addition of 5 x 10(-5) M bumetanide or 10(-4) M ouabain. In filters treated with CT, Isc and net chloride flux (JClnet) increased after 60 min from 0.05 +/- 0.008 and -0.04 in the Ringer to 0.32 +/- 0.05 and -0.33 mueq.h-1.cm-2, respectively. Addition of 10(-2) M glucose further raised Isc by stimulating net sodium flux (JNanet) (0.70 +/- 0.08 and + 0.58 mueq.h-1.cm-2, respectively). This additional augmentation of Isc was reversed by 0.5 mM phlorizin and was mimicked by 3-O-methyl-D-glucose. When the filters were stimulated by cAMP for 15 min, Isc was also enhanced by addition of glucose. In untreated filters, Isc, JNanet, and JClnet did not differ significantly before and after addition of glucose. It is concluded that HRT-18 cells in basal state do not display absorptive properties but secretory properties stimulated by CT. However they exhibit Na+-glucose cotransport once stimulated by either CT or cAMP.