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Biomedical subjects

F Ahrens

Publications and source records attributed to F Ahrens.

At least 19 recordsLinked to original sources
PubMed2006

Release and permeation of histamine in isolated caecum epithelia of pigs.

OBJECTIVE: The objective was to investigate the role of histamine in the porcine caecum with special regard to its release and permeation. MATERIAL AND METHODS: Caecal epithelia were mounted in Ussing chambers. Mast cells were stimulated by A23187 (1 micromol/l). Permeation and changes in short-circuit current (Isc) were assessed after unilateral application of 3H-labelled histamine (100 micromol/l). Mucosal-to-serosal (ms) and serosal- to-mucosal (sm) flux rates were calculated based on the contralateral appearance of radioactive histamine label (hist-rad; representing histamine plus catabolites) as well as histamine. 14C-mannitol fluxes were measured to assess paracellular permeability. RESULTS: Both A23187 and serosal addition of histamine increased Isc of caecal epithelia. The Isc increase due to A23187 was associated with an elevated histamine release from epithelia. A discrepancy between hist-rad and histamine fluxes (P<0.05) indicated efficient histamine catabolism (ca. 85%), which was decreased by blockage of diamine oxidase through aminoguanidine. Fluxes of histamine were correlated to 14C-mannitol fluxes. Fluxes of hist-rad and histamine were higher in the sm direction. CONCLUSIONS: Histamine can be released from endogenous stores and acts on the epithelium. The absorption of luminal histamine is predominantly restricted by paracellular permeability and catabolism. The latter is only partially catalysed by diamine oxidase.

Animals↗
PubMed2003

Effect of potentially probiotic lactobacilli on faecal enzyme activity in minipigs on a high-fat, high-cholesterol diet-a preliminary in vivo trial.

Minipigs were fed a "Western-style", high-cholesterol diet for a baseline period, followed by the diet containing a mixture of three Lactobacillus strains with potential probiotic features, after which a normal pig diet was followed. The faecal enzyme activity for beta-glucuronidase and azoreductase, which are commonly considered as markers for procarcinogenic activity, was significantly reduced during the 5 weeks of "probiotic" supplementation. During the period of Lactobacillus administration, the cell counts for total anaerobes increased, whereas the total number of aerobes showed no change.

Animals↗
PubMed2003

Effect of nitric oxide on electrolyte transport across the porcine proximal colon.

The effect of nitric oxide (NO) on ion transport in the porcine proximal colon was investigated in slide-stripped epithelia mounted in Ussing chambers. The serosal addition of the NO-donors sodium nitroprusside (SNP, 0.5 mM) or S-nitroso-N-acetylpenicillamine (SNAP, 0.5 mM) induced a steep increase of short-circuit current ( I(sc)). The stimulatory effect of SNP on I(sc) could not be blocked by piroxicam or tetrodotoxin. Potassium channel inhibitors (quinidine, tetraethylammonium or barium) added serosally reduced the SNP- or SNAP-induced increases of I(sc). In chloride-free solutions, the SNP-induced increase of I(sc) was smaller than in chloride-containing solutions. Cl(- )and Na(+) flux measurements demonstrated that SNP diminished Cl(-) and Na(+) net absorption. Pre-treatment with barium was able to block the inhibitory effect of SNP on NaCl net absorption totally. NO effects on paracellular pathways were assessed by measuring flux rates of [(14)C]-D-mannitol. SNP did not change unidirectional D-mannitol flux rates. In conclusion, NO inhibits NaCl net absorption in the proximal colon of pigs by acting directly on the enterocyte. The antiabsorptive (and/or prosecretory) effect of NO depends on a functional basolateral potassium conductance.

Animals↗
PubMed2003

Histamine-induced chloride secretion is mediated via H2-receptors in the pig proximal colon.

OBJECTIVE: The aim of this study was to investigate the action of histamine on function of epithelia in the pig proximal colon. MATERIAL AND METHODS: Isolated epithelia of the pig proximal colon were prepared by slide-stripping and mounted in Ussing chambers. Short-circuit current (Isc) was measured after serosal addition of histamine (20 micromol/l) with or without pretreatment with histamine receptor antagonists (H1: chlorpyramine, 10 micromol/l; H2: famotidine, 100 micromol/l; H3: thioperamide, 10 micromol/l), a cyclooxygenase inhibitor (indomethacin, 10 micromol/l), or a neuronal conduction blocker (tetrodotoxin, 1 micromol/l). Alternatively, histamine receptor agonists (H1: 2-pyridylethylamine; H2: dimaprit; H3: R-alpha-methylhistamine, each 100 micromol/l) were added to the serosal side. Flux studies using 14C-mannitol, 22Na+ and 36Cl- were performed in the presence of 100 micromol/l histamine on the serosal side. RESULTS: Serosal application of histamine induced a rapid rise in Isc with a maximum 3 min after addition, followed by a slow decrease. Only pretreatment with famotidine decreased the epithelial response to histamine. Pretreatments with chlorpyramine, thioperamide, indomethacin or tetrodotoxin did not change histamine-induced increases in Isc. Action of histamine could be simulated by dimaprit, but not by 2-pyridylethylamine or R-alpha-methylhistamine. Histamine induced an increase in serosal-to-mucosal chloride flux leading to a decrease of chloride net absorption. Fluxes of sodium and mannitol were not affected by histamine. CONCLUSIONS: In contrast to the importance of H1-receptors in other gut epithelia, histamine acts directly via H2-receptors in the porcine proximal colon. Changes in Isc after histamine addition are primarily due to chloride secretion. The paracellular permeability is not influenced by histamine.

Animals↗
PubMed2003

Luminal salmonella endotoxin affects epithelial and mast cell function in the proximal colon of pigs.

BACKGROUND: Salmonellosis and systemic endotoxaemia affect intestinal function. However, little is known about the functional importance of luminal Salmonella (S.) endotoxin during intestinal infection. METHODS: Pigs were either given or not given lipopolysaccharide (LPS, 30 mg day(-1)) of S. Typhimurium DT-104 orally for 14 days. Blood samples were taken weekly. After slaughter (day 14), epithelia of the proximal colon were investigated in Ussing chambers. Bacterial translocations to lung, liver, spleen and several lymph nodes were determined by culture. RESULTS: Endotoxin feeding increased plasma C-reactive protein (CRP) and histamine levels without evoking clinical signs. Postmortem, proximal colonic epithelia of LPS-treated animals showed both a decreased histamine release after mast cell stimulation with A23187 and a smaller increase in short-circuit current after A23187 application. Addition of the nitric oxide donor, sodium nitroprusside (SNP), also elicited lower increases in short-circuit current in the proximal colon of endotoxin-treated pigs. Endotoxin pre-feeding decreased colonic ion conductance, although mannitol and histamine fluxes were high in some epithelia of this group. Luminal Salmonella endotoxin increased bacterial translocation to proximal jejunal lymph nodes. LPS applied to colonic epithelia in vitro had no electrophysiological effects. CONCLUSIONS: Luminal endotoxin elicits an acute phase response and affects intestinal electrolyte transport and mast cell function. Furthermore, LPS induces epithelial spots of increased mannitol permeability that could be identical to spots of enhanced bacterial translocation.

Acute-Phase Reaction↗
PubMed2001

Congenital cystic adenomatoid malformation type 4.

A 9-day-old boy presented in respiratory distress and with failure to thrive. The chest X-ray showed a hyperlucent area of the left lung. A resection of the markedly emphysematous segment 2 of the left upper lobe was performed assuming the emphysematous tissue was due to congenital lobar emphysema (CLE). Histological examination of the lung tissue, however, revealed a pattern consistent with congenital cystic adenomatoid malformation (CCAM) type 4. The therapy for CLE as well as for CCAM is similar, i.e., resection of the emphysematous tissue. As far as the prognosis is concerned, it is important to diagnose the exact type of malformation in order to exclude associated anomalies, as well as the risk of development of malignancies in later life. The frequency of associated malformations of CCAM type 4 is unknown. Although the risk for development of malignancies from CCAM type 4 is not clear at the moment, the possible development of malignancies justifies prompt resection shortly after diagnosis, even in asymptomatic patients. A life-long follow-up in those patients who had a resection of CCAM in early childhood is recommended.

Cystic Adenomatoid Malformation of Lung, Congenita↗
PubMed1998

Characterisation and selection of probiotic lactobacilli for a preliminary minipig feeding trial and their effect on serum cholesterol levels, faeces pH and faeces moisture content.

Three out of 297 Lactobacillus strains isolated from pig faeces were selected for a feeding trial on account of their high bile-salt hydrolase (BSH) activity, bile-salt resistance, low pH tolerance and the production of antimicrobial substances. Two strains were identified as Lactobacillus johnsonii and one as Lactobacillus reuteri by DNA-DNA hybridisation. L. johnsoniii BFE 1061 produced a bacteriocin active against a range of lactic acid bacteria (LAB) and nonrelated bacteria including Clostridium perfringens. Six minipigs were maintained on a high-fat, high-cholesterol ('Western Style') diet for 17 weeks after which the diet was supplemented with the 'probiotic mixture' containing the above mentioned three Lactobacillus strains at 2 x 10(12) CFU per pig per day for five weeks. The mixture was given as a resuspended lyophilisate. During a two week follow-up period the minipigs received only the 'Western-style' diet without probiotic supplementation. A lowering effect on serum cholesterol levels was indicated after three weeks probiotic feeding, concomitant with an increase in the moisture content of the faeces and Lactobacillus cell numbers. Triglycerides, pH and number of lactic acid bacteria in faeces were not significantly influenced by probiotic supplementation.

Animals↗
PubMed1994

Dietary pectin's effect on ileal and fecal amino acid digestibility and exocrine pancreatic secretions in growing pigs.

The effect of dietary pectin on apparent ileal and fecal digestibilities of protein and amino acids and on pancreatic secretions was studied in two experiments with growing pigs (initial weight 70 kg). Four barrows were fitted with simple T-cannulas for collection of ileal digesta; another four barrows were fitted with permanent re-entrant cannulas for collection, sampling and subsequent return of pancreatic juice. Dietary pectin included at a level of 7.5 g/100 g in a cornstarch-based diet significantly depressed apparent ileal and fecal protein and amino acid digestibilities. This depression in the small intestine could be attributed to both an increase in endogenous protein secretions and a decrease in the efficiency of digestion. In the large intestine, pectin was used by intestinal microbes as the principal energy source to catabolize nitrogenous compounds and to stimulate bacterial nitrogen assimilation, thus altering the amino acid profile of protein voided in feces. The inclusion of pectin did not affect the flow of pancreatic juice or the total secretion of protein, lipase, trypsin and chymotrypsin. However, there was a significantly lower secretion of alpha-amylase, which was a direct result of the replacement of starch by pectin. The results demonstrate that pectin may have a detrimental effect on the processes of protein digestion and absorption but does not affect the secretion of pancreatic proteolytic enzymes in pigs.

Amino Acids↗
PubMed1994

Effect of level of dietary neutral detergent fiber on ileal apparent digestibility and ileal nitrogen losses in pigs.

A study was conducted with 20 barrows (average BW 25 kg) to determine the effect of various levels of neutral detergent fiber (NDF) in the diet on the apparent ileal nutrient digestibility and ileal diaminopimelic acid (DAPA) content, and consequently on the amount of ileal endogenous nitrogen. The pigs were fitted with a post-valvular T-cecal cannula. They were fed .8 kg/d of a corn starch-based semisynthetic diet formulated to contain equal amounts of protein and starch and 0, 60, 120, or 180 g of purified NDF/kg of diet, included at the expense of glucose. The purified NDF (pNDF) was isolated from wheat bran using an incubation procedure with pancreatin. Ileal digestibility of NDF was approximately 17% and was independent of the pNDF level in the diet. By increasing the amount of pNDF in the diets, apparent ileal digestibilities of dry matter (DM), nitrogen (N), neutral detergent insoluble N (NDF-N), and ash decreased linearly (P < .05). The DAPA content of the ileal digesta (g/d) was not affected by the percentage of pNDF in the diets. Calculation of the ileal bacterial N excretion indicated that more than 50% of the ileal N was of bacterial origin. With increased percentage of dietary pNDF, both endogenous and exogenous N in ileal chyme were linearly increased (P < .05). Thus, an increase in the dietary fiber content leads to a decreased apparent ileal protein digestibility due to increased ileal losses of both endogenous and exogenous protein.

Animal Feed↗
PubMed1994

Mammary and renal excretion of purine metabolites in relation to energy intake and milk yield in dairy cows.

This investigation was conducted to quantify the purine excretion of cows and to evaluate milk allantoin as an estimator of synthesis of microbial protein in the rumen. Concentrations in plasma of allantoin and uric acid and their excretion in urine and milk were determined using 16 Holstein cows at 21 to 315 d of lactation and yielding 8 to 36 kg/d of milk. The mean daily intake of a 55:45 roughage and concentrate diet was 16.3 kg of DM with 106 MJ of NEL and 13.8 to 16.0% CP. Total urine was collected over 24 h, plasma samples collected four times, and milk samples collected twice on the same day. Analyses of purine metabolites were performed with HPLC. On average, excretion of allantoin in urine and milk was about 294 and 4.1 mmol/d for allantoin and 35 and 1.1 mmol/d for uric acid. Excretion of allantoin in milk was correlated to concentration in plasma (r = .84). As milk yield increased, percentage of milk allantoin increased from .6 to 2.4% of total allantoin excretion (r = .85). The correlations of NEL intake with allantoin excretion in milk (r = .80) and in urine (r = .84) were similar. Daily milk yield was correlated with plasma allantoin (r = .78) and milk allantoin excretion (r = .95). We concluded that determination of milk allantoin is a useful, noninvasive method to monitor rumen microbial protein synthesis.

Allantoin↗
PubMed1993

[Legionellosis in a newborn infant].

We describe a case of successful therapy of a neonatal Legionellosis with Erythromycin. On his 6th day of life a full term newborn with normal body weight was affected by a severe pneumonia. This was at first resistant to therapy and required mechanical ventilation. Diagnosis of Legionella pneumophila serotype 1 was made by culture from bronchial lavage. Only few cases of neonatal Legionellosis have been reported until now. In three cases diagnosis was made post mortem.

Bronchoalveolar Lavage Fluid↗
PubMed1992

[Preparatory feeding of the dry stage cow in regard to nutritional condition and the status of the rumen mucosa and rumen flora at calving].

Excessive fat deposition prior to calving and a negative energy balance post partum predispose the high producing cow for an intensive postpartal lipolysis and for the health problems resulting thereof. It was postulated that a well proliferated ruminal mucosa at the beginning of lactation could improve the energy supply by stabilizing the pH of the rumen content with energy rich feed and by providing a high absorption capacity for volatile fatty acids. Results of earlier experiments dealing with this problem are reviewed. Furthermore there is described a pilot experiment with 9 dry cows, which was directed to stimulate rumen mucosa growth ante partum by a low energy ration (roughage) during the first half of the dry period and a high energy ration during the last 3 to 4 weeks prior to calving, without inducing a fat cow. The ruminal mucosa reacted to that feeding regimen as expected and desired. The body weight of 3 cows in moderate and 4 cows in medium body condition increased by 7.2% or 3% during 8 to 11 or 7 to 9 weeks respectively. One of two fat cows lost 4.9% of her body weight within 8 to 9 weeks while the condition of the second animal remained unchanged. No problems were observed at calving. A further progress is expected by feeding the dry cows in two groups with different rations according to their body condition at the end of lactation. Results of experiments as well as practical experiences show that no more than 8 to 10 days are necessary to adapt the ruminal flora to a mixed ration (roughage + concentrates).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1992

Effect of ileo-rectal anastomosis and post-valve T-caecum cannulation on growing pigs. 1. Growth performance, N-balance and intestinal adaptation.

The effects of post-valve T-caecum (PVTC) cannulation and end-to-side ileo-rectal anastomosis (IRA) on growth performance, nitrogen retention and intestinal fermentation were measured in growing pigs by comparison with a control group of intact animals. There were no differences between PVTC-pigs and intact pigs in growth performance and N balance. In IRA-animals reduced growth (P < 0.01), less efficient feed conversion (P < 0.01) and decreased N retention (P < 0.001) were found. Indices of fermentation measured in ileal digesta of PVTC- and IRA-pigs were considerably different. In IRA-animals the concentration of volatile fatty acids (VFA) was about 112-162 mmol/l, higher (P < 0.001) than in digesta of PVTC-pigs (20-31 mmol/l). The molar proportions of acetate and propionate depended (P < 0.01 and P < 0.001 respectively) on the digesta-collection technique. Concentrations and ratios of VFA measured in PVTC-pigs were similar to reported values. Diaminopimelic acid (DAPA) concentration and N:DAPA ratios measured in digesta were significantly (P < 0.05 and P < 0.001 respectively) different between treatments. All digesta variables measured showed increased microbial activity in digesta of IRA-pigs; thus, an influence on digestibility measurement can be assumed.

Adaptation, Physiological↗
PubMed1992

Tracer studies of urea kinetics in growing pigs: II. The effect of starch infusion at the distal ileum on urea recycling and bacterial nitrogen excretion.

Six gilts, with an average BW of 70 kg, were fitted with a simple T-cannula at the distal ileum to study the effect of continuous starch infusion on urea kinetics by means of a radioisotope dilution technique. The pigs were fed twice daily 600 g of a cornstarch-based diet formulated to contain 16% CP by supplementation with isolated soy protein. Infusion of starch, compared with water, decreased (P < .05) plasma urea concentration, urea pool size, and entry, excretion, and degradation rates; urea turnover rate and urea space were not affected (P > .05). Expressed as a percentage of total entry rate, approximately 40% of urea was recycled into the digestive tract in both infusion treatments. The stimulation of microbial fermentation in the large intestine resulted in an increase (P < .05) in fecal N excretion, which was mainly due to an increased excretion of bacterial N. This increase could not be attributed to a greater secretion of urea into the large intestine and its subsequent utilization by the intestinal microflora. The increased bacterial N assimilation after starch infusion led to a reduction in ammonia absorption from the large intestine, which in turn was reflected by a reduced urinary N excretion. As a result, the overall N balance was not affected. In a second experiment, two barrows, with an average BW of 80 kg, were fed twice daily 1.4 kg of a cereal-based diet. The body urea pool of both pigs was labeled with a single injection of 1 g and 2 g of [15N]urea, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗