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How the epidemic obesity appeared in the United States during the eighties. Respective intake of fats, proteins and saccharides in the diet is notified. Sugars such as sucrose provide pleasure and reward specially by infants and children. Lactose occurs in the life of the newborn with a peculiar situation; its sweetening effect is weak and devoid of any neurochemical stimulation. The amounts of lipids and sugars in the daily diet are frequently excessive if physical activity is inappropriate. TV dinners are specially endangered. Eating too much snacks disrupts the physiological rhythm of the digestive economy. The carbonated soft beverages' are used instead of water, affording large amounts of inapparent sugars. Ice creams are often too rich in sugars and lipids. Fruits and vegetable fibers fail in the diet.

Lactose is the main source of energy supplied to the newborn mammalian in its mother's milk. Because of its lower sweeting power, lactose is unable to induce a reaction as does dextrose. Lactose does not lead to release of mediators such as endorphins or dopamine and is free of reward effects.

Health effects of lactic acid bacteria ingested in fermented milk. Many recent studies have shown the health effects of various strains of lactic acid bacteria in humans and animals and have tried to describe their action mechanism in the digestive tract. A number and a variety of potential beneficial effects have been published. Some of these effects have already been described such as the improvement of lactose digestion and the treatment of diarrheal disorders. Other health effects are still a subject of controversy such as the decrease of serum cholesterol and the reduction of tumor formation. The aim of this article is to summarize the probiotic effects of lactic acid bacteria, their mechanisms, and the fate of these microorganisms during their transit in the digestive tract.

Secondary active transport is defined as the transport of a solute in the direction of its increasing electrochemical potential coupled to the facilitated diffusion of a second solute (usually an ion) in the direction of its decreasing electrochemical potential. The coupling agents are membrane proteins (carriers), each of which catalyzes simultaneously the facilitated diffusion of the driving ion and the active transport of a given solute. The review starts with some considerations on the energetics followed by a presentation of the kinetics of secondary active transport. Examples of information which may be gained by such studies are discussed. In the second part, some examples of secondary transport are given; we also describe the characteristics of the corresponding carriers. The various transport systems presented are: the D-glucose/Na+ symport in brush-border membranes, the lactose/H+ symport in E. coli, the Na+/H+ antiport, the different transport systems in the inner mitochondrial membrane.

In this study, we used fasted, preruminant calves fitted with a double proximal cannula in the duodenum; gastric evacuation was investigated by recovering products leaving the abomasum after a test meal. Five types of meal were given: whole milk, skimmed milk, casein solution in water, casein solution in a mineral medium simulating the permeate of highly-filtered milk, and whey. Gastric emptying of nitrogen was relatively slow. The coagulation of "milk diets" slowed down this emptying. Precipitation of "casein diets" at acid pH also slowed down emptying, but to a lesser degree. The "casein diets", more proteolyzed than the "milk diets", released larger amounts of non-protein nitrogen (NPN) into the intestine. Calcium emptying was highly related to NPN emptying, demonstrating the important role of acid peptides (phosphopeptides) from casein hydrolysis.

The incidence of lactose intolerance was determined in 31 women with idiopathic postmenopausal osteoporosis. Nine subjects exhibited a pathological rise in blood glucose (less than 20 mg/100 ml) after receiving 50 g lactose. The absorption of glucose and galactose, xylose, and fat was normal in the 31 patients. Daily intake of calcium was below the normal range in 3 subjects with and in 6 subjects without lactose intolerance. The association between lactase deficiency and osteoporosis is stressed.

Three diets rich in inulin, saccharose and lactose, respectively, were given to 10 rumen-fistulated sheep. Two animals were defaunated, two were inoculated with either Polyplastron multivesibulatum or Entodinium sp., and two others were inoculated with both. The latter two were bred in conventional conditions. All animals ingested the same amounts of carbohydrates in the three diets (21-22 g/kg P0.75/day). Dietary nitrogen content was similar (table 1). The ciliate population was improved with the inulin diet (fig. 1; table 2). With a mixed population, the Entodinium improved with the inulin diet (fig 1; table 2). With a mixed population, the Entodinium sp. genus was always predominant. Holotrich protozoa (mainly Isotricha) in the rumen of the conventional sheep represented 15 to 30% of the total ciliate biomass, indicating that they were able to metabolize these soluble sugars. We also observed that P. multivesiculatum can ferment cellulose and all the soluble carbohydrates proposed in these diets. However, Entodinium sp. development occurred mainly in the presence of the sugard produced during carbohydrate hydrolysis by other ciliates or bacteria. The highest organic matter digestibility, noted in faunated animals (table 3) was confirmed by the VFA concentration in the rumen (table 4). This could be explained either by an activation of bacterial metabolism due to predation or by the direct effect of ciliates on fermentations, or both. Modifications in the VFA composition varied with ciliate inoculation, showing that ciliate metabolism may vary with the nature of the energy in the diet or that the observed results depended on various opposite effects in which the intensity of each component was influenced by the diet. In general, the acetic acid molar proportion increased and propionic acid decreased when there was a considerable Entodinium sp. population. The effect on butyric acid was low with these diets. Higher ammonia and lactic acid concentrations were observed in the rumen of faunated than defaunated sheep, irrespective of the ciliate inoculum.

Gastric digestion of milk proteins has been studied in the preruminant calf by analysing gastric effluents in the duodenum after the ingestion of 5 different diets: whole milk, skim milk, casein solution in water, casein solution with minerals, whey. The amino acid composition of the gastric effluents and HPLC analysis of the latter show that the major part of the whey proteins were evacuated rapidly without any proteolysis and after milk ingestion. On the contrary, all the caseins were largely proteolysed and arrived slowly in the gut. The major part of the peptides obtained came from alpha s1 casein. Only a few peptides, principally CMP, were quickly emptied from the stomach.

To determine the sensitivity and specificity of breath hydrogen (H2) in detecting lactase deficiency, breath H2 collected by end-expiratory sampling and capillary blood glucose were measured after ingestion of 50 g of lactose in 36 patients with biopsy-proved isolated lactase deficiency, 42 with normal lactase activity and 6 with lactase deficiency secondary to mucosal lesions. All patients had digestive symptoms clinically compatible with lactose malabsorption. The maximum increase in breath H2 concentration was more than 1.1 mumol/l (25 ppm) in all patients with isolated lactase deficiency, and less than 0.88 mumol/l (20 ppm) in 88% of patients with normal lactase activity; there were 5 false-positive results, attributed in one case to small bowel colonization and in another case to rapid transit after gastric surgery. Secondary lactase deficiency was accurately detected by neither breath H2 nor blood glucose.

The purpose of the present article is to give a survey of present knowledge of the ecological relationships between the various bacterial populations composing the microflora of the digestive tract of the host animal. Analysis of the relationships can be made with the aid of recent techniques: utilization of axenic animals (germ-free) and of gnotoxenic animals inoculated with known bacterial populations; perfecting of bacteriological techniques for the quantitative differential analysis of the various bacterial populations in the digestive tract, especially in the case of strictly anaerobic species. Some characteristics of the equilibrium between the various bacterial populations in the different segments of the gastro-intestinal tract have been described as well as some of the mechanisms which regulate this equilibrium. These mechanisms either imply interactions between bacteria or the action of the host animal and the environment on the microflora. Lastly, various examples concerning the action of the microflora in the digestive tract on the nutritional physiology of the host animal are given; action on the anatomy of the digestive tract and on the metabolism of carbohydrates, proteins, lipids and vitamins.

Effect of Prolonged Consumption of Lactose or Hydrolyzed Lactose in Rats.--5. Intestinal Metabolism of Glucose and Galactose. The intestinal metabolism of galactose is different according to the form of ingestion. With a lactose diet (L), the galactose is abundant in intestinal contents (Tab. I), since neither the intestinal flora (Tab. II), nor the epithelial tissue (Tab. III) can easily metabolize the galactose. The glucose disappears more rapidly than the galactose (Tab. I). With a hydrolyzed lactose diet (LH), the intestinal contents of two hexoses are identical (Tab. I). In this case, the enzymic activity of epithelium metabolizes an amount of galactose 6 times as big as with the lactose diet (Tab. III).

The compatibility groups of eleven plasmids determining metabolic characters used in taxonomy and isolated from naturally-occurring strains were examined. Seven of these plasmids determined lactose fermentation. Two were fi+: one of these belonged to group FI and the other to a novel group. Of the remainder, which were fi-, one (which also determined chloramphenicol resistance) belonged to group H; the others were compatible with representative plasmids from every group so far recognized. Two plasmids determined sucrose fermentation. Both were fi-: one belonged to group H, the other was compatible with plasmids of every group. Two plasmids determined haemolysin production. One was fi+ and belonged to group FIII; the other was fi- and belonged to group I2. Plasmids belonging to known compatibility groups and determining metabolic characters only should prove particularly useful in the classification of plasmids determining antibiotic resistance.

A Gram positive bacillus, strictly anaerobic, was isolated from the viscera of all diseased birds showing lesions of necrotic enteritis. Its morphology and biochemical reactions, the presence of alpha and thêta hemolysins and the production of a lecithinase-C in vitro, all these characteristics indicated a similarity to those belonging to the group of Clostridium perfringens. The two hemolysins were neutralized in vitro only by the antitoxin A. Broiler chickens injected I.V. with a Viande-Foie (VF) broth culture of Clostridium perfringens together with the antitoxin A survived, whereas those receiving antitoxin C died. These results seem to indicate that this organism belongs to the type A. This bacillus was sensitive to a great variety of antibiotics, except neomycin.

The absorption of calcium corresponds to a strictly determined mechanism inhibited by phosphates and activited by carbohydrates. We investigate in what extent the absorption of milk calcium from various species has the same proceeding. 4 months old rats are given orally solutions of CaCl2 alone or in combination with sodium dihydrogen phosphate or lactose or these both compounds. We compare calcium absorption of these solutions to that of milk from woman, cow or sow, or to dilutions of these two latter milks. All these fluids are dosed so that they correspond each other by their respective content in total calcium, total phosphorus and lactose. Each solution contains 45Ca. Blood samples 1,30, 4, 6 and 24 hours after ingestion allow establishing the variations of plasma radioactivity. Rats are sacrified after 24 hours. In certain cases, samples from digestive tube contents and feces provide a coefficient of calcium absorption. The osseous retention is obtained from femur radioactivity. In breif, we may consider that milks from cow and sow provide calcium the absorption of which is settled after their respective content of total phosphorus and lactose. Opposed effects of these inhibitors and activators of calcium absorption compensate so that calcium from these milks is just a little better utilized by adult rat than calcium from an isocalcic solution of CaCl2. Calcium from woman milk, rich in carbohydrates, poor in total phosphorus is better absorbed than that from the two latters, however less than we might expect from its high lactose content. We may wonder that calcium utilization from cow milk is as moderate as that of a solution of CaCl2. But skeleton mineralization which may be fulfilled by milk is made better because of that: it is not chloride but calcium phosphate which ensures this mineralization, a phosphate which alone would impair this mineralization without the compensative role of lactose.

Lactase activity has been measured in the pancreas, the small and large intestine of 79 pigs varying in age from 6-7 months. The endogenous enzyme level fluctuated along the small intestine but the activity did not vary according to the level of lactose fed in the diet either just after weaning or from 25 to 100 kg of live weight. Measurements performed in the content of the intestine showed that lactose could be digested by the enzymes of the microflora mostly active in the ileum, the caecum and the large intestine.

Nutritional balances are made with groups of 12 rats Wistar receiving well-balanced diets with 40 p. 100 of sucrose (T), or 40 p. 100 of lactose (L and P), or hydrolyzed lactose (LH and PH). Whey (L) and ultrafiltration permeate (P) are used in crude state or after enzymic industrial lactase hydrolysis (LH and PH). The animals consume diets during eight months. Faeces contain neither lactose nor galactose, but glucose in small quantities. In all urines occurs about 0,5 mg/day of glucose. The lactose diets (L and P) provoke a week lactosury (0,36 p. 100 of ingestion). Galactose and galactitol are abundant in urines: with lactose diets (L and P), the urinary excretion is equal to 4 p. 100 of ingested galactose. In urines of hydrolyzed lactose diets (LH and PH) the excretion reaches 26 p. 100 of ingestion. In this case the excretion is remarkably invariable from third day of eighth month: the urinary galactose corresponds to 23 p. 100 and galactitol to 3 p. 100 of consumed galactose. The urines of lactose diets (L and P) and hydrolyzed lactose diets (LH and PH) contain 100 and 300 mg/day of non sugar reducing substances respectively, i.e. 40 p. 100 of total urinary reducing power. The apparent retention of lactose (L and P) is 95,5 p. 100 and that of the hydrolyzed lactose (LH and PH) is 86 p. 100 after 8 months of experiment but it is estimated that digestive flora consumes 40 p. 100 of dietary lactose (L and P).

Lac- mutants of Escherichia coli which presented a growth triggered by adding glycine betaine to the medium were isolated and characterized. Glycine betaine restores beta-galactosidase (strain AM 12) and lactose permease (strain AT42) activities. It is suggested that the right and active conformation of these enzymes, lost during mutagenesis, is restored, in vivo, in presence of this betaine.

The beta-galactosidase (EC 3.2.1.23) activities of wild-type Rhizobium meliloti and its lactose slow-hydrolyzing mutant have been compared. The properties of the enzyme are very different in each strain. These differences allow us to prove that two enzymes with a beta-galactosidase activity can be found in the wild-type whereas only one enzyme remains in the mutant strain.

Lac+ variants of Salmonella montevideo were recovered from mating with an Escherichia coli strain harbouring the thermosensitive sex-factor Ft114-lac+. The properties of these variants suggest that this F' factor behaves identically in Salmonella and Escherichia. From these variants, it is possible to select mutants in which lac expression is stable at high temperature (42 degrees C) and it was proved that they behave as Hfr's. Twelve independently isolated Hfr's were similar with respect to both point of origin and sequence of markers transferred. These results suggest that our strain of S. montevideo carries an F-factor affinity site near met C gene.

Among 17 lactose-fermenting species of Enterobacteriaceae (735 strains studied), only Escherichia coli could grow at 44 degrees C in brilliant green/ bile/lactose/L-tryptophan broth (BLBVB-T) with production of gas and indole. When the inoculum was from a lactose+ colony developed on selective or differential agar media commonly used in enteric bacteriology, detection of gas and indole in BLBVB-T after 8 to 18 h incubation at 44 degrees C allowed good identification of E. coli. The use of a single-test medium for the identification of lactose+ E. coli saves time and money.

At the steady-state of accumulation of intracellular lactose by the beta-galactoside permease of Escherichia coli, the rate of efflux of the substrate is equal to its rate of influx. An original experimental method and a mathematical processing of the experimental data are proposed to evaluate the relative involvements of the permease-mediated pathway and of the diffusion component in this efflux. The method consists of inducing the lac operon of the bacteria, and then of removing the inducer and allowing the cells to grow further. The permease content and the membrane surface of diffusion are thus varying independently in such a "de-induction" experiment, along which lactose uptake has been monitored at different times. The analysis of the experimental data show that, under conditions of maximal induction, over 95% of the efflux passes through the energized permease. The relevant parameters of the efflux of lactose have been computed and their values allow the prediction of most classical observations, as well as the prediction, never checked, that under physiological conditions, the higher the external substrate concentration, the higher the permease-mediated efflux, according to a saturation kinetics.

The atypical lactose positive characters have been found to be plasmidmediated in 6 strains of Enterobacter hafniae and 2 strains of Proteus morganii. One of the P. morganii plasmid possesses the fi+ character, all the other plasmids belonging to the fi-group. Both plasmids of P. morganii could be transduced and remained then readily transferably by conjugation. Two of the E. hafniae plasmids were found unstable when harboured in Salmonella typhi grown at 40 degrees centigrade, when they were stable in the same strain grown at 37 degrees. The other plasmids were stable in the original strains, in S. typhi, in Escherichia coli both at 37 degrees and 40 degrees. These results are discussed according to investigation about (lactose plasmids) of which a bibliographic review is presented here.