Loss of CNFY toxin-induced inflammation drives Yersinia pseudotuberculosis into persistency

Gastrointestinal infections caused by enteric yersiniae can become persistent and complicated by relapsing enteritis and severe autoimmune disorders. To establish a persistent infection, the bacteria have to cope with hostile surroundings when they transmigrate through the intestinal epithelium and colonize underlying gut-associated lymphatic tissues. How the bacteria gain a foothold in the face of host immune responses is poorly understood. Here, we show that the CNFY toxin, which enhances translocation of the antiphagocytic Yop effectors, induces inflammatory responses. This results in extensive tissue destruction, alteration of the intestinal microbiota and bacterial clearance. Suppression of CNFY function, however, increases interferon-γ-mediated responses, comprising non-inflammatory antimicrobial activities and tolerogenesis. This process is accompanied by a preterm reprogramming of the pathogen's transcriptional response towards persistence, which gives the bacteria a fitness edge against host responses and facilitates establishment of a commensal-type life style.

Impact of CCR7 on T-Cell Response and Susceptibility to Yersinia pseudotuberculosis Infection

Background

To successfully limit pathogen dissemination, an immunological link between the entry tissue of the pathogen and the underlying secondary lymphoid organs (SLOs) needs to be established to prime adaptive immune responses. Here, the prerequisite of CCR7 to mount host immune responses within SLOs during gastrointestinal Yersinia pseudotuberculosis infection to limit pathogen spread was investigated.

Methods

Survival, bacterial dissemination, and intestinal and systemic pathology of wild-type and CCR7-/- mice were assessed and correlated to the presence of immune cell subsets and cytokine responses throughout the course of infection.

Results

The CCR7-/- mice show a significantly higher morbidity and are more prone to pathogen dissemination and intestinal and systemic inflammation during the oral route of infection. Significant impact of CCR7 deficiency over the course of infection on several immunological parameters were observed (ie, elevated neutrophil-dominated innate immune response in Peyer's patches, limited dendritic cell migration to mesenteric lymph nodes [mLNs] causing reduced T cell-mediated adaptive immune responses (in particular Th17-like responses) in mLNs).

Conclusions

Our work indicates that CCR7 is required to mount a robust immune response against enteropathogenic Y. pseudotuberculosis by promoting Th17-like responses in mLNs.

Natural Killer Cells Mediate Protection against Yersinia pseudotuberculosis in the Mesenteric Lymph Nodes

Natural killer cells play a crucial role in the initial defense against bacterial pathogens. The crosstalk between host cells infected with intracellular pathogens and NK cells has been studied intensively, but not much attention has been given to characterize the role of NK cells in the response to extracellular bacterial pathogens such as yersiniae. In this study we used antibody-mediated NK cell depletion to address the importance of this immune cell type in controlling a Y. pseudotuberculosis infection. Analysis of the bacterial counts was used to follow the infection and flow cytometry was performed to characterize the composition and dynamic of immune cells. Depletion of NK cells led to higher bacterial loads within the mesenteric lymph nodes. We further show that in particular CD11b⁺ CD27⁺ NK cells which express higher levels of the activation marker CD69 increase within the mesenteric lymph nodes during a Y. pseudotuberculosis infection. Moreover, in response to the activation NK cells secrete higher levels of IFNy, which in turn triggers the production of the proinflammatory cytokine TNFα. These results suggest, that NK cells aid in the clearance of Y. pseudotuberculosis infections mainly by triggering the expression of proinflammatory cytokines manipulating the host immune response.

15N tracer kinetic investigations on the protein metabolism in a child with chronic renal failure fed a protein-restricted diet

Administration of EAA and KA in patients with CRF on a protein-restricted diet led to a favourable influence on the plasma protein turnover. This was demonstrated by an increase in the half-life and a decrease in the breakdown rate of plasma proteins measured by the 15N tracer technique.

A direct link between the global regulator PhoP and the Csr regulon in Y. pseudotuberculosis through the small regulatory RNA CsrC

In this study we investigated the influence of the global response regulator PhoP on the complex regulatory cascade controlling expression of early stage virulence genes of Yersinia pseudotuberculosis via the virulence regulator RovA. Our analysis revealed the following novel features: (1) PhoP activates expression of the CsrC RNA in Y. pseudotuberculosis, leading to activation of RovA synthesis through the CsrABC-RovM cascade, (2) activation of csrC transcription is direct and PhoP is shown to bind to two separate PhoP box-like sites, (3) PhoP-mediated activation results in transcription from two different promoters closely downstream of the PhoP binding sites, leading to two distinct CsrC RNAs, and (4) the stability of the CsrC RNAs differs significantly between the Y. pseudotuberculosis strains YPIII and IP32953 due to a 20 nucleotides insertion in CsrC(IP32953), which renders the transcript more susceptible to degradation. In summary, our study showed that PhoP-mediated influence on the regulatory cascade controlling the Csr system and RovA in Y. pseudotuberculosis varies within the species, suggesting that the Csr system is a focal point to readjust and adapt the genus to different hosts and reservoirs.

[SGB IX - Magna Charta of a Functional Participation Philosophy]

Further development of needs-based, efficient health care structures in particular for people with chronic illness, and in conjunction with them, is the paramount objective of SGB IX, book 9 of the German social code. To achieve this it is necessary to define treatment sequences across sectoral boundaries in health care, and to establish cooperation between community-practice physicians, hospitals, rehab and long-term care facilities, cost carriers, and people with disabilities. In this context, the article discusses the current rank of rehabilitation and participation, points out the underlying conflicting issues and interests, and posits the preventive-integrative rehabilitation paradigm at the very centre of health protection networking.

Early warning-system for operation-failures in biological stages of WWTPs by on-line image analysis

By the observation and evaluation of the microscopic picture of activated sludge samples it is possible to introduce another biological parameter additional to conventional physico-chemical parameters for the control of biological stages of waste water treatment plants. Considering the fact that parameters like floc size and floc size distribution, structure of the flocs (compact/open), shape of the flocs (round/irregular) allow perceptions of the adjusted operation conditions of the biological stages, evidence for changing operation conditions or threatening operation disturbances can be recognised. This recognition takes place at a very early phase, because the morphology of activated sludge flocs reacts very fast to changing conditions. An automatic image analysis of activated sludge floc pictures would enable the introduction of a new sum parameter to enhance operation control of aeration tanks. By a statistical evaluation of the processed sludge images several parameters can be used to describe the alteration of activated sludge flocs characteristics. With these biological parameters it is possible to detect altered operation conditions or threatening or existing operation problems at an early phase. Thus it is possible to plan suitable countermeasures. Furthermore, the microscopic picture is the only parameter, that gives important information about the structure of the activated sludge flocs and the biozenosis. In comparison with the mainly used physico-chemical parameters, that just give information about the inlet and outlet of the wastewater treatment plants, the microscopic picture is the only parameter that gives information about the biology of the wastewater treatment process. By means of this biological parameter an improved control and regulation of the biological stages of wastewater treatment plants can be obtained.

[Effects of oral administration of bifidobacteria on intestinal microflora in premature and newborn infants]

In a prospective, randomised study the effects of orally administered bifidobacteria on the intestinal microflora were investigated in 100 preterm and term neonates under intensive care conditions during the first 21 days of life. The 50 infants (group with bifidobacteria) received lyophilized bifidobacteria (Töpfer Bifidus) via nasogastral tube with an initial dosage of 3 times daily 1.25 x 10(8) bifidobacteria on day 2 of life and a daily dosage of 6 times 1.25 x 10(8) bifidobacteria on day 3 until day 21 of life. The other 50 infants (control group) did not receive bifidobacteria. The preterm and term neonates were fed either with pasteurized mother's milk or milk from healthy female donors (n = 79) or with an infant formula (Alfaré, n = 13) or initially with Alfaré and thereafter with mother's milk (n = 8). The intestinal microflora of preterm and term neonates under intensive care conditions could be influenced by the oral administration of bifidobacteria. The administration of bifidobacteria resulted in the group of inoculated infants in a significantly earlier colonization of bifidobacteria (8.1 +/- 3.9 days of life) than in the control group (11.3 +/- 4.7 days of life). On day 7 a bifidobacterial dominance (> 90% of the intestinal microflora) could be found in 26% of infants with inoculation of bifidobacteria and only in 2% of the control group (p < 0.001). These significant differences could be shown until day 21 of life. A difference in septicemia frequency between the two groups could not be demonstrated. At the beginning of the infection a bifidobacterial dominance was found in only one of 23 cases of septicemia.

Uterine bleeding in postmenopausal women on continuous therapy with estradiol and norethindrone acetate. Endometrium Study Group

OBJECTIVE

To investigate the incidence of uterine bleeding during 12 months of treatment with 17beta-estradiol (E2) 1 mg, unopposed or in combination with three doses of norethindrone acetate.

METHODS

This study was a prospective, double-masked, randomized, multicenter trial. A total of 1176 healthy postmenopausal women age 45 years and older without evidence of endometrial abnormalities were randomly assigned to receive either unopposed E2 1 mg, or continuous-combined formulations of E2 1 mg and norethindrone acetate 0.1 mg, 0.25 mg, or 0.5 mg. Any spotting or bleeding episodes during the treatment period were recorded in a daily diary and reported by weekly telephone calls.

RESULTS

The incidence of bleeding was low in the combination groups, even during the initial 3 months of treatment (24-28%), after which it decreased with increasing doses of norethindrone acetate. Conversely, the incidence of bleeding increased over time with unopposed E2 1 mg. After the initial 3 months, the incidence of bleeding among the combination groups was lowest in the norethindrone acetate 0.5 mg group. Among women initiating therapy close to menopause, fewer reported bleeding with norethindrone acetate 0.5 mg than with the other combination groups. There was a significantly (P<.05) lower discontinuation rate due to bleeding in the norethindrone acetate 0.5 mg group compared with all other treatment groups.

CONCLUSION

Continuous-combined formulations of E2 1 mg with norethindrone acetate 0.1, 0.25, or 0.5 mg are associated with a low incidence of uterine bleeding. After the initial 3 months of treatment, bleeding profiles improved with increasing doses of norethindrone acetate.

[Persistent Lactobacillus casei subspecies rhamnosus bacteremia in a 14 year old girl with acute myeloid leukemia. A case report]

The present clinical observation is related to a 14-year-old girl suffering from acute myeloid leukemia. The clinical course was complicated by episodes of severe enterocolitis, E. coli- septicemia, pancreatitis and pneumonia. In the course of continued cytostatic and antibiotic treatment a persistent asymptomatic Lactobacillus casei subsp. rhamnosus-bacteremia became detectable by a total of 18 blood cultures. Microbial cultures of the faeces revealed colony-forming unites of this germ in orders of 10(9)/g. Antibiotic eradication attempts according to the resistogram were not successful. The Lactobacillus-bacteremia disappeared only after 13 months when the cytostatic therapy was terminated. An adjuvant influence of the Lactobacillus infection on the outcome of the underlying disease cannot be excluded.

[Comparison of gastric emptying, blood glucose, and oro-cecal transit times after a conventional morning meal and a Kollath breakfast]

Blood glucose kinetics and intestinal transit times were investigated in 12 adult volunteers aged 28 to 52 years after ingestion of a conventional morning meal made up of white flour rolls, butter, marmalade, and coffee with sugar as compared with an isocaloric Kollath-breakfast consisting of whole wheat flakes as a basis. For estimation of gastric emptying time the sodium-[13C]acetate breath test technique was used. Oro-coecal transit time and gastric emptying were determined by simultaneous administration of lactose-[13C]ureide and consecutive drawings of breath samples in intervals of 15, 30, and 60 min through 12 h. The 13CO2-excess of the breath test samples was measured by continuous flow isotope ratio mass spectrometry. The postprandial rise in blood glucose following the ingestion of the Kollath-breakfast was lower as compared with the conventional morning meal, showing significant differences between the 90 min values and the area below the blood glucose curve. The half time of gastric emptying was not different between the two breakfast versions (1.7 vs. 1.6 h). The oro-coecal transit time averaged out at 4.2 h after the Kollath-breakfast and 5.3 h following the conventional morning meal. Likewise, there were no significant differences in the coecal retention time nor in the cumulative percentage of 13CO2-exhalation between the two breakfast versions. Concerning the blood glucose kinetics the differences in the nutritional physiology between the breakfast based on whole wheat flakes and the conventional breakfast as claimed by Kollath were only detectable in outlines in our study. Gastric emptying time showed no differences between the two breakfast versions.

15N-tracer studies in formula-fed preterm infants: the role of glycine supply in protein turnover

In preterm infants, protein-turnover rates obtained by [15N]glycine as a tracer are known to be overestimated. This may reflect the insufficient supply of dietary glycine. In this randomized study, the influence of a glycine-rich diet on whole body protein turnover rates in eight male preterm infants (29-32 weeks, 1,200-2,540 g birthweight) using the 15N-tracer technique on days 21 and 28 of life was investigated to evaluate the necessity of supplementing preterm infant formulas with proteins rich in glycine. Before and during the study, the infants were alternately fed with a commercial available preterm infant formula (I, 2% protein, 40 mg glycine/dl) and a variety of this formulation with glycine-rich proteins (II, 2% protein, 130 mg glycine/dl). The protein-turnover rates were computed after 15N-single-pulse labeling with the help of the three-compartment model (TCM) and the urinary ammonia end-product method (AEPM). The tracer used was [15N]glycine (dosage: 2 mg 15N/kg). For the determination of 15N-excess-excretion kinetics, fractionated urine specimens were collected over a 36-h period. The protein-turnover rate calculated by TCM was 8.8 +/- 1.6 g/kg/day (formula I) and 7.7 +/- 2.0 g/kg/day (formula II); using AEPM, the rate was 8.7 +/- 2.5 g/kg/day and 7.5 +/- 1.5 g/kg/day, respectively. We conclude that the presaturation of the precursor pool by an adequate glycine intake minimizes drawbacks that may arise when using [15N]-glycine as a tracer in preterm infants, and a protein concentration of 2%, as in formula I, and consequently, a 170% glycine content when compared with the same human milk volume, meets the glycine requirement.

alpha-Lactalbumin-enriched low-protein infant formulas: a comparison to breast milk feeding

Tryptophan (TRP) is the limiting amino acid in low-protein infant formulas. This is mainly due to lower alpha-lactalbumin (alpha LA) content in cow's milk whey as compared with human milk protein. To study the effect of alpha LA-enrichment on the TRP supply, cross-over studies were carried out in 20 healthy infants up to 3 months of age. In this study, two protein-reduced (1.3%) infant formulas (moderate TRP content of 1.88% and higher TRP content of 2.10%) were alternately fed over a 2 week period in two groups of infants. Serum TRP levels of the formula-fed infants with the higher TRP content did not differ significantly from an exclusively breastfed control group of 11 infants (10.5 +/- 4.8 versus 10.9 +/- 4.7 mg l-1, p = 0.841), whereas levels of the formula-fed infants with the moderate TRP content were significantly lower (7.4 +/- 3.9, p = 0.038). The supplementation of alpha LA resulting in a higher TRP supply to low-protein diets is a further step towards the production of infant formulas more closely adapted to human breast milk.

Tracer kinetic studies on a methionine-supplemented soy-based infant formula using 1-13C- and 15N-methionine as tracers

A tracer-kinetic study using 1-13C- and 15N-labeled L-methionine was conducted in order to measure the retention rate of free methionine added to commercially-produced soy-based infant formulas. Twelve male infants, fed on a soy formula, received a single-pulse labeling by oral administration of L-1-13C-methionine (5 mg/kg) and L-15N-methionine (10 mg/kg). The abundance of expired 13C-labeled CO2 was measured up to 7 h after administration at 15-, 30-, and 60-min intervals. Additionally, enrichment of total 15N and 15N in urinary ammonia were determined up to 48 h after administration. Retention rates of the labeled carboxyl group amounted to an average of 91.2% (SD 4.1) of the intake. A similar retention rate was measured for the 15N-label of methionine (90.0%, SD 4.3). The data point at the efficacy of methionine supplementation of soy-based infant formulas.

Enhancement of lysozyme trypsin-mediated decay of intestinal bifidobacteria and lactobacilli

Lysozyme-mediated lysis of Bifidobacteria and Lactobacilli was studied in in vitro tests using the agar gel plate and turbidometric Micrococcus luteus (lysodeikticus) procedure as a standard. Suspensions of the strains Bifidobacterium infantis, B. infantis liberorum, B. breve, B. longum, B. ssp, and Lactobacillus acidophilus proved to be resistant to egg white lysozyme and human milk lysozyme when incubated at 37 degrees C in concentrations of 5, 50, and 500 mg lysozyme/L, respectively, through 30 and 60 min. Heat treatment at 100 degrees C for 1 h and pretreatment with ether, acetone, ascorbic acid, and hydrogen peroxide failed to incline the bacteria to the lytic effects of lysozyme. Consecutive incubation of the lysozyme-pretreated bacteria with trypsin resulted in a significantly enhanced bacteriolysis in all strains of bacteria, with the exception of B. longum. The mode of action of lysozyme and proteolytic enzymes on Bifidobacteria and Lactobacilli offers an explanation for the release of microbial building blocks and their colonic absorption and retention in the breast-fed baby.

Committee report: childhood diet and prevention of coronary heart disease. ESPGAN Committee on Nutrition. European Society of Pediatric Gastroenterology and Nutrition

Coronary heart disease is a major cause of morbidity and mortality in Europe, particularly northern, central, and eastern Europe. Several strategies have been recommended for children and adolescents to promote a healthy lifestyle and thereby reduce the risk of coronary heart disease in later life. The European Society of Pediatric Gastroenterology and Nutrition (ESPGAN) Committee on Nutrition reviewed some of these strategies, and our conclusions and recommendations are reported herein.

[Sialic acid in breast milk and infant formula food]

OBJECTIVE

Sialic acid (N-acetylneuraminic acid, NANA) is an essential component of mucins, glycoproteins and gangliosides and therefore important for the function of cell membranes, membrane receptors and the normal development of the brain. The capacity of the metabolic pathway for the synthesis of sialic acid from glucose and other carbohydrate sources in preterm infants and term-born neonates is currently unknown.

METHODS

In the present study the overall nutritional sialic acid supply of infants was analysed by means of HPLC-based determination of sialic acid concentrations in a total of 51 human milk samples obtained from nursing mothers at different stages of lactation. The data were compared with 3 commercial preterm infant formulas, 7 adapted infant formulas, 11 partially adapted infant formulas, 4 follow-up and 2 soy-based formulas.

RESULTS

The sialic acid concentration in colostrum and transitory human milk was 1300 +/- 322 mg/l. After the 10th day of lactation the concentration dropped to 983 +/- 455 mg/l (p < 0.01). Preterm infant formulas contained 197 +/- 31, adapted formulas 190 +/- 31, partially adapted formulas 100 +/- 33, follow-up formulas 100 +/- 33 and soy-based formulas 34 +/- 9 mg sialic acid/l, respectively.

CONCLUSIONS

Formula-fed infants obtain less than 20% of the amount of sialic acid supplied if breast-fed. A sufficient sialic acid supply may be essential in very-low-birth-weight infants and neonates at risk for the normal development of brain function.

[Quo vadis--infant nutrition in the European Community? A comment on the guideline of the EC Commission on initial infant and subsequent nutrition]

The new European Community guidelines on infant nutrition formulas, their contents and their declaration, effective since January 1993, do not indicate a scientifically sound progress in infant nutrition. Several of the contents listed (i.e. carbohydrates) may be of potential risk to health. In the future, European paediatricians will have to occupy themselves more concisely with the contents of marketed infant formulas. Individual solutions may have to be found for some patients.

[Phosphate concentration. Does reduction in infant formula feeding modify the micro-ecology of the intestine?]

The potential influence of phosphates in formulas on intestinal microflora was studied in 25 infants, aged 8 days to 12 weeks. The babies were either fed an infant formula with the usual phosphate concentration (n = 10) or an infant formula with reduced phosphate and protein concentrations (n = 7). The microbiological findings were compared with those obtained from breastfed infants (n = 8). Low-phosphate concentrations did not correlate with a predominance of bifidobacteria or suppression of putrefactive bacteria in the feces. The fecal excretion of phosphates and fat was found to be significantly lower with mother's milk compared to formulas both rich and poor in phosphate. Protein synthesis and breakdown rates, as well as the net protein gain, did not have a significant correlation with protein intake.

Is mother's milk the most suitable food for very low birth weight infants?

Human milk feeding (HMF) as compared with formula feeding (FF) has the advantage of more effective utilization of proteins, fat, minerals and trace elements. HMF provides passive immunologic protection and active immunostimulation. It prevents the VLBWI from antigenic and toxic loads. The disadvantage of HMF is the high volume required tomeet the energy and protein needs of the VLBWI and the growing potential risk of AIDS, hepatitis and cytomegaly infections which makes human milk banking increasingly difficult. The current concept of VLBWI formula feeding (FF) is based on high protein, energy and mineral concentrations to compensate for the lower biological value, for lower bioavailability and for side effects related to the antigenicity of food proteins. FF as compared with HMF results is increased mineral and water retention, in high renal load and in a completely different body composition. The risk of necrotizing enteritis is significantly higher. All this has to be considered a challenge to further adapt LBWI formulas to the amino acid composition of human milk protein to induce bifidogenic effects and to provide sufficient amounts of essential fatty acids and carbohydrates which serve as building stones for normal brain development.

Whole-body protein parameters in premature infants: a comparison of different 15N tracer substances and different methods

[15N]glycine, [15N]leucine, and [15N]yeast protein thermitase hydrolysate (YPTH) as tracers for investigating the protein turnover rates in premature infants were studied in nine human milk-fed neonates (born after 32 to 34 wk of gestation) by paired comparison of the tracers. The 15N enrichment of total urinary nitrogen and ammonia after administration of a single oral dose of 15N was measured by emission spectrometry. Flux rates were calculated using a three-compartment model and the ammonia end product method. The mean whole-body protein synthesis rates, as determined by the three-compartment model derived from the three 15N tracers, differed significantly (p less than 0.01) among [15N]glycine (15.9 g/kg/d), [15N] leucine (9.1 g/kg/d), and 15N-YPTH (5.9 g/kg/d). When the corresponding rates were determined from the excretion of label in ammonia, the results showed the opposite tendency; the lowest apparent synthesis rates were found after [15N]glycine (7.5 g/kg/d), followed by [15N]leucine (14.4 g/kg/d), and the highest figure resulted after [15N] YPTH (16.7 g/kg/d). The results of this comparison substantiate the assumption that there are methodologic errors in connection with the use of different tracers and models for the calculation of whole-body protein parameters in preterm infants, with respect to the main requirement for tracer kinetic studies; the tracer nitrogen must be representative of total amino acid nitrogen. Seen in this light, mixtures of completely labeled amino acids such as YPTH may represent the most reliable tracer substance.(ABSTRACT TRUNCATED AT 250 WORDS)

[Carbohydrates in parenteral nutrition solutions in pediatrics--a critical evaluation]

Application of carbohydrates in pediatric infusion therapy has recently been limited to glucose and xylitol. Fructose and sorbitol, which formerly had been used widely as energy sources in parenteral nutrition, have meanwhile been banned in order to prevent fatal complications in patients with undiscovered hereditary disturbances in fructose metabolism. The aim of this review is to focus the attention on potential side effects and limitations of glucose administration in pediatric infusion therapy. With special regard to total parenteral nutrition in preterm infants, sufficient glucose conversion to N-acetylneuraminic acid and other carbohydrate building blocks of glycoproteins and gangliosides is to be placed in question. This might have consequences for normal brain development and can be considered a challenge for future research work in this field.

Kohlenhydrate in parenteralen Nährlösungen für die Pädiatrie – eine kritische Bewertung

Die Anwendung von Kohlenhydraten in der pädiatrischen Infusionstherapie ist neuerdings auf Glukose und Xylitol eingegrenzt worden. Fruktose und Sorbitol, die früher in großem Umfang als Energiequellen in der parenteralen Ernährung genutzt wurden, sind inzwischen wegen der Gefahr tödlicher Komplikationen bei Kindern mit unentdeckten angeborenen Fruktosestoffwechselstörungen aus dem Infusionsprogramm verbannt worden. Der Sinn und Zweck dieser Übersicht liegt darin, die potentiellen Nebenwirkungen und Grenzen der Glukose in der pädiatrischen Infusionstherapie zu umreißen. So muß z.B. speziell in Frage gestellt werden, ob Frühgeborene unter den Bedingungen der totalen parenteralen Ernährung in ausreichender Menge N-Azetylneuraminsäure und andere Kohlenhydratbausteine von Glykoproteinen und Gangliosiden aus Glukose als einziger Kohlenhydratquelle synthetisieren können. Dies hätte u.a. Konsequenzen für die Hirnentwicklung und stellt eine Herausforderung für zukünftige Forschungen auf diesem Gebiet dar.

Symbiotic interactions between colonic microflora and protein metabolism in infants

The utilization of 15N nitrogen from 15N-labelled bifidobacteria for whole body protein synthesis was studied in 4 infants by oral single-pulse labellings and in 3 other infants, who had colostomies, by colonic pulse labellings. The bifidobacteria were harvested from a modified Petuely culture medium containing 15N ammonium chloride and 15N cystine as the only sources of nitrogen. The tracer dose chosen for the balance studies was 3 mg 15N/kg. 15N concentrations in urine and feces collected over 48 hours after the pulse labellings were determined by emission spectrometry. Oral administration of 15N-labelled bifidobacteria resulted in absorption of approximately 90% renal excretion of 15%, and fecal excretion of 12% of the tracer dose, respectively. Retention in the protein pool averaged 73%. After colonic single pulse labelling with 15N-labelled bifidobacteria, the corresponding values were 85.5%, 2.2%, 14.5% and 83.0%, respectively. Absorption and incorporation of the heavy nitrogen into body proteins were directly demonstrated by increased 15N atom percent excess values within the trichloroacetic acid (TCA) supernatants and the proteins of the plasma, 0.25 and 0.04 atom%, respectively, at 24 hours after oral pulse labellings. One half of the total 15N excreted in urine consisted of urea and approximately 8% was eliminated as ammonia.

[Fecal sIgS and lysozyme excretion in breast feeding and formula feeding]

The bioavailability of sIgA and lysozyme from human milk was investigated in a total of 41 infants by radial immunodiffusion and by the Micrococcus lysodeicticus method, respectively. In four different pools of human milk used for balance studies the sIgA concentrations ranged between 2,200 and 17,850 mg/l. The lysozyme concentration varied from 64.5 to 283.5 mg/l. On human milk feeding the excretion of sIgA in 19 infants was 3,200 (0-8,200) mg per litre and 9.7 (0-131) mg lysozyme per litre, respectively. Corresponding values on formula feeding in 22 infants were 1030 (0-6400) and 2.6 (0-9) mg/l. Fecal sIgA excretion was significantly higher on human milk than on formula feeding. Balances of sIgA and lysozyme intake and excretion as performed in 9 infants revealed a less than 1% fecal excretion of both the protective substances. In vitro digestion of raw human milk with pepsin at pH 2 and 3 resulted in a rapid disappearance of immunologically reactive sIgA within 30 minutes after starting the incubation, while no changes in sIgA content were detectable at pH 4. Lysozyme proved to be resistant against peptic digestion. Tryptic digestion at pH 8 did not result in a decrease of human milk sIgA within 120 minutes of incubation at 37 degrees C while under analogous conditions lysozyme concentration approached to 0. These results point at the full bioavailability of both sIgA and lysozyme from human milk. The differing resistance of these protective substances against pepsin and trypsin is apparently adapted to physiological particularities of the digestive tract in early infancy.

[Determination of protein nitrogen utilization with (15N) yeast protein in short bowel syndrome]

The digestive and absorptive capacity for food protein was studied in 8 infants with short bowel syndrome by means of [15N] yeast protein as a tracer substance. The extent of resection ranged from total removal of the small bowel to partial closures of the large bowel by colostomies. The tracer substance was administered as single oral pulse labeling in a dosage of 5 mg 15N/kg. The fecal losses of 15N were extremely high in cases of total and subtotal resection of the small bowel as well as after operative removal of the Bauhins valve. In the entirety they ranged between 3 and 95% of the intake. The corresponding 15N-retention in the protein pool was in the range between 0.1 and 91.6%. Operative findings, nutritional state and passage time were of limited value for the prediction of food protein assimilation. Even residual lengths of 25 cm of the small bowel turned out to be compensated, which was shown in one of the infants by an absorption of 97% and a retention rate of 84%. The oral [15N] yeast protein loading can be considered a reliable test for the evaluation of protein nitrogen absorption and utilization in short bowel syndromes.

[The bifidogenic effect of breast milk. Theories and facts]

Human milk has the unique capability to originate and maintain a predominance of bifidobacteria in the large bowel of infants. There is evidence, that besides other protective factors this special microbiologic effect may have beneficial influences on the resistance against enteral infections as well as on a symbiotic utilization of some milk components. This is the reason, why there have been many attempts in past to imitate the bifidogenic effect in infant formulas. The different theories formed for the classification of this principle focus on either the low buffer capacity of mother's milk, the mutarotation of lactose and the existence of antimicrobial and bifidus growth factors, respectively. The bifidogenic principle is, however, in all probability not related to only one of these factors. It can rather be considered a complex of interacting factors, of which rapid gastric emptying due to the relatively high concentration of free amino acids and peptides, missing bacterial colonization of the small bowel, absence of antigenic effects of the food protein and low enterocyte regeneration may play an additional role. These aspects can be looked upon as a challenge for further research on mother's milk composition and on the metabolic effects of its constituents in future.

Zur Verminderung der Immunogenität von Milchproteinen durch Desialinisierung

Die antigene Wirkung eines nativen Molkenprotein/Casein-Gemisches im Verhältnis 60:40 wurde im Vergleich zu einem durch die Warrensche Hydrolyse desialinisierten Gemisch gleicher Zusammensetzung im Immunisierungsversuch an je 3 Kaninchen untersucht. Die im Mittel 4200 g schweren Tiere erhielten je 2mg des Antigens insgesamt 6mal parenteral injiziert. Die Blutentnahme erfolgte am 80. Tag des Immunisierungsversuchs. Das Serum der mit dem nativen Molkenprotein/Casein-Gemisch immunisierten Tiere präzipitierte im Mancini-Test das injizierte Antigen intensiv. Das desialinisierte Proteingemisch zeigte demgegenüber nur eine stark abgeschwächte Präzipitation. Bei den mit desialinisiertem Kuhmilchprotein immunisierten Kaninchen lieβen sich Antikörper gegen das desialinisierte wie auch gegen das native Molkenprotein/Casein-Gemisch nur in Spuren nachweisen. Auf die Konsequenzen dieser Ergebnisse für die Säuglingsernährungspraxis und die Optimierung von Diätnahrungen wird hingewiesen.

[15N tracer kinetics of the utilization of yeast nitrogen]

The utilization of nitrogen from 15N-labeled Saccharomyces cerevisiae cells was studied in 6 infants by means of oral pulse labeling, comparing native and heat-treated yeast cells. The 15N dose used was 3 mg/kg. The body weight of the subjects varied between 5500 and 9400 g. The yeast cells were harvested from a culture medium which contained 15N ammonium chloride as the only source of nitrogen. The 15N-enrichment of the cells amounted to 95 atom-%. In the course of 48 h following the administration of the native yeast cells, 11% of the tracer dose were renally excreted. The corresponding value after labeling with heat-treated yeast cells was 17.9%. The cumulative renal excretion of the tracer tended to be faster as compared with pulse labeling of the native yeast cells. A paired comparison with labeled native and heated yeast cells in 3 subjects did not reveal any differences in the retention rate of 15N. When untreated 15N yeast cells were administered, 13.2% of the tracer dose were excreted in the urine and 10% respectively in the faeces. The retention was 76.8%. After single pulse labeling with 3 mg 15N/kg from heat-treated yeast cells the corresponding values were 19.4%, 4.4% and 76.2%, respectively. The kinetic of the renal 15N excretion points at the partial absorption of the yeast nitrogen from the colon.

Excretion of 15N and incorporation into plasma proteins after high-dosage pulse labelling with various tracer substances in infants

The suitability of a biosynthetically produced [15N] yeast-protein-thermitasehydrolysate ([15N] YPTH), [15N] yeast protein and [15N] glycine for use as 15N-tracers was tested in three groups of four infants each. The [15N] YPTH was obtained by hydrolysing 15N-labelled yeast protein with thermitase, a proteinase from Thermoactinomyces vulgaris. Following oral single-pulse labelling in a dosage of 10 mg 15N/kg body weight the 15N-excretion in stools and urine as well as the 15N-abundance in plasma proteins and in the TCA-soluble plasma fraction were determined. The [15N] YPTH differs from [15N] glycine in terms of the complete distribution of 15N among all 20 amino acids. This could be demonstrated by a distinctly lower [15N]ammonia (0.5 per cent) and a higher [15N2] urea excretion (5.0 per cent) compared with [15N] glycine (1.2 and 3.4 per cent respectively). The faecal loss of 15N from the [15N] YPTH was 3.7 per cent of the tracer dose, while the corresponding value after administration of [15N] yeast protein was found to be 7.4 per cent on average. There were no differences between the tracer substances in terms of the measured 15N-abundance in the plasma proteins (mean: 0.07 atom per cent excess) and in the TCA-soluble fraction (mean: 0.21 atom per cent excess).

Evidence for colonic absorption of protein nitrogen in infants

The absorption of protein nitrogen by the colon was assessed in 6 infants with colostomy by giving 15N yeast protein in a dosage of 5-20 mg 15N/kg (92.4 atom-% 15N). The absorption of 15N ranged between 87.1 and 98.1% of the administered dose, and the retention in the protein pool ranged between 79.0 and 94.2%. The incorporation of 15N in the plasma proteins was demonstrated by 15N excess values between 0.02 and 0.10 atom-%. The results suggest that the colon can assimilate proteins when insufficient absorption of protein nitrogen in the small intestine occurs. The breakdown of protein is thought to result from the action of colonic flora.

Sperm wash in three culture media: maximization of motile sperm recovery during swim-up incubation

Three different culture media commonly used during in vitro gamete manipulations were studied for their efficacy in sperm wash procedure. Highest numbers of motile sperm were recovered at 6 hours following incubation in WT-6 and Ham's F-10 media. However, WT-6 yielded higher motile sperm numbers than Ham's F-10. Swim-up sperm number reached a peak at 3 hours following incubation in BWW. A period of 2 to 6 hours of incubation of sperm pellets overlayed with sperm wash media resulted in highly enriched motile sperm fractions free of dead spermatozoa and seminal debri.

15N tracer techniques for the differential diagnosis of dwarfism and prediction of growth hormone action in children

[15N]Glycine in a single oral dose was used to study nitrogen turnover in 18 short children, aged 3-14 yr. On the basis of their serum GH responses to insulin-induced hypoglycemia, the patients were divided into 3 groups: complete GH deficiency (GHD; n = 5); partial GH deficiency (pGHD; n = 6), and children with constitutional growth delay and familial short stature (CGD/FSS; n = 7). The mean 48-h renal excretion of 15N by patients with GHD was 66.09 +/- 14.12% (+/- SD) of the tracer dose. This decreased to 27.64 +/- 5.33% after two injections of 10 IU/m2 GH (P less than 0.001). 15N excretion by patients with pGHD was 47.19 +/- 13.42%, and it decreased after GH injection to 22.69 +/- 4.58% (P less than 0.005). Patients with CGD/FSS had 15N excretion of 37.27 +/- 5.68%, and it did not change in response to GH. The mean protein synthesis rate in GHD patients was extremely low, and it increased after GH injection from 0.99 +/- 0.46 to 3.53 +/- 0.43 g/kg X day. In pGHD patients the protein synthesis rate increased from 2.62 +/- 0.84 to 4.50 +/- 1.09 g/kg X day. The CGD/FSS patients had no change in protein synthesis rate after GH. Our results suggest that studies of the metabolism of [15N]glycine might be of value in predicting responsiveness to GH therapy.