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Biomedical subjects

T Midtvedt

Publications and source records attributed to T Midtvedt.

At least 145 records · Page 8Linked to original sources
PubMed1985

The establishment of some microflora associated biochemical characteristics in feces from children during the first years of life.

This report presents a new approach to the study of the colonization of the digestive tract after birth. We have examined the development of four microflora associated characteristics, MACs, defined as the recording of any anatomical structure, biochemical or physiological function in the macroorganism, which has been influenced by the microflora. These MACs may create a basis for later investigations into the impact of diarrheal diseases and antibiotic therapy. The following biochemical characteristics were studied in feces from children of 0-61 months of age: conversion of cholesterol to coprostanol and bilirubin to urobilins, inactivation of trypsin and degradation of mucin. These results indicate establishment of microbes capable of converting bilirubin to urobilins within the second year of life. The mucin degrading and cholesterol converting microbes are established in most of the children during the same period. Tryptic activity was found to be absent in meconium, present in feces from all children up to 21 months of age, and absent in 6 out of 15 children in the age group 46-61 months. The study indicates that the establishment of the MACs in the digestive tract is a remarkably long drawn out process.

Age Factors↗
PubMed1985

Age-related changes of human serum antibodies to dietary and colonic bacterial antigens measured by an enzyme-linked immunosorbent assay.

IgG, IgA and IgM antibody activities in human serum to six dietary and eight gut-related microbial antigens were measured by an enzyme-linked immunosorbent assay (ELISA). IgG activities to five of the dietary antigens decreased with age; IgM activities to four of them were weaker in old people than in children. Old people showed weaker IgM but stronger IgG activities to some of the microbial antigens than children did. A decline in IgG and IgM antibody titres to most dietary antigens with increasing age is consistent with the development of systemic hyporesponsiveness due to continuous antigenic stimulation of the intestinal immune system. Persistence of microbial antigens in the gut, moreover, may lead to systemic hyporesponsiveness of IgM-producing cells. Concurrently raised IgG titres to three of the bacteria might be explained by antigenic stimulation outside the intestinal immune system.

Adolescent↗
PubMed1985

Clindamycin-induced alterations in intestinal microflora-associated characteristics in rats.

Conventional Sprague-Dawley rats were treated with clindamycin, 40 mg/kg/day and 0.04 mg/kg/day, for 5 days. At a dose of 40 mg/kg/day, microflora-associated characteristics (MACs), such as shape, color, and consistency of feces, proteolytic activity, electrophoretic pattern, and cholesterol and bilirubin metabolism were transformed into values like those found in germfree rats: germfree animal characteristics (GACs). The effect on the proteolytic activity lasted longest. It did not disappear until one or two enemas with cecal contents from intact conventional rats were administered. At a dose of 0.04 mg/kg/day, effects on the proteolytic activity and cholesterol metabolism were seen. With the exception of one rat, the effect on proteolytic activity did not disappear until one or two enemas were given. The results indicate that clindamycin, even in very small daily doses, has a profound and long-lasting influence on many intestinal MACs in rats.

Animals↗
PubMed1985

Short-chain fatty acids in the small-bowel bacterial overgrowth syndrome.

The short-chain fatty acids (SCFAs) have been measured by gas chromatography in fasting jejunal secretions, saliva, and feces from 8 patients with the small-bowel bacterial overgrowth syndrome (BO) and 9 control patients; in jejunal secretions and saliva from 6 healthy subjects; and in feces from 20 healthy subjects. The concentrations of SCFAs (median (range), mumol/l) in jejunal secretions of BO patients were as follows: total, 990 (210-12,370); acetic acid, 650 (170-6770); propionic acid, 110 (16-3070); isobutyric acid, 26 (1-310); n-butyric acid, 90 (12-1340); isovaleric acid, 35 (2-680); n-valeric acid, 7 (3-200). In BO patients the total concentration of SCFAs in jejunal secretions was approximately four times higher than in control patients (p less than 0.01) and in healthy subjects (p less than 0.025). The relative distribution of the acids resembled the distribution found in feces more than that of saliva or the normal jejunal secretions. These findings indicate that patients with BO have a colon-like flora in the small intestine and that the main part of the SCFAs in the jejunal secretions of these patients is produced by the altered microbial flora in the jejunum. Combined with other tests, analyses of intestinal SCFAs may prove to be valuable in the diagnosis of small-bowel bacterial overgrowth.

Adult↗
PubMed1985

Short-chain fatty acids in intestinal content of germfree mice monocontaminated with Escherichia coli or Clostridium difficile.

The short-chain fatty acids (SCFAs) have been analysed in coecal and small-intestinal content of conventional (CONV) and germfree (GF) mice, in germfree mice monocontaminated with Escherichia coli (MEC) or Clostridium difficile (MCD), and in germfree mice conventionalized by the visitor technique (EXG). The total concentrations of SCFAs in coecal content, measured by gas chromatography, were (mean (SD), mmol/kg): CONV, 125.2 (32.9); GF, 1.02 (0.39); MEC, 6.88 (0.76); MCD, 4.50 (0.12); and EXG, 115.6 (17.4). The concentrations of SCFAs were 3- to 25-fold higher in the coecum than in the small intestine in CONV, MEC, and EXG mice (p less than 0.05). The fermentation patterns (that is, the relative composition of the acids) of E. coli and Cl. difficile were distinctively different under defined in vitro conditions and similar to those found in intestinal content of monocontaminated animals. Combined gas chromatography and mass spectrometry showed that Cl. difficile produced an unusual metabolite, 2-methylbutyric acid, in vitro and in vivo. The findings indicate that the fermentation patterns are closely related to the bacteria. Variations in the bacterial flora may be more important in determining the concentrations and patterns of SCFAs in intestinal content than variations in the intake of substrate for SCFAs formation as dietary fibre.

Animals↗
PubMed1985

Rapid determination of antibiotic susceptibility by a disc diffusion test for urgent clinical situations.

Employing the PDM method, disc diffusion antibiotic susceptibility tests were read after 4 and 8 h and compared to traditional readings after 18 h. Four hours of incubation was not found suitable. After 8 h of incubation, all the 74 strains tested showed visible growth and more than 75% of the readings fell in the same sensitivity groups. Nearly all the discrepancies observed could be classified as minor, and reading the plates after 8 h of incubation should be considered as a valuable alternative when the clinical need for rapid information is obvious.

Anti-Bacterial Agents↗
PubMed1985

Dissociated effect of amphotericin B and desoxycholate on phagocytosis of Escherichia coli by human polymorphonuclear neutrophils.

The influence of commercial amphotericin B-desoxycholate (Fungizone) and desoxycholate alone on phagocytosis of Escherichia coli by human polymorphonuclear neutrophils in vitro was studied. A dissociated effect of amphotericin B and desoxycholate was observed. Amphotericin B was shown to stimulate the ingestion of Escherichia coli through an effect on the bacteria as well as on the neutrophils. Desoxycholate inhibited phagocytosis through an effect on the neutrophils and also, at low concentrations (0.08 microgram/ml), through an effect on the bacteria. On the other hand, pretreatment of Escherichia coli with high concentrations (8.2 micrograms/ml) of desoxycholate rendered it more susceptible to phagocytosis. The elimination of bacterial breakdown products from the neutrophils after ingestion of Escherichia coli was also inhibited by desoxycholate and stimulated by amphotericin B. Most of these effects disappeared in the presence of 10% serum. An alteration of bacterial hydrophobicity could only partly explain the effect of amphotericin B.

Amphotericin B↗
PubMed1984

Methods for determination of conjugated bilirubin in rat faeces.

Conjugated bilirubin was prepared from the faeces of germ-free (GF) rats by three different preparative methods. The bilirubin conjugate preparations were coupled with diazotized ethyl anthranilate and the formed ethyl anthranilate azopigments were quantified spectrophotometrically and separated by thin-layer chromatography (tlc). The most polar azopigment was purified by tlc and subjected to ammonolysis followed by tlc of the released saccaride. As a result of this procedure, only glucuronic acid was detected as the conjugating saccaride thus indicating that the most polar azopigment prepared from GF rat faeces was the delta ethyl anthranilate azopigment. Reference azopigments were prepared from GF rat small intestinal contents and subjected to separation by tlc. The azopigment pattern was very similar to the pattern obtained with the faecal azopigment preparations and a maximum of ten separated azopigment spots were detected. The findings indicated that, in addition to bilirubin glucuronides, other bilirubin conjugates with unknown structure are excreted with the faeces of GF rats. One of the preparative methods used for the preparation of conjugated bilirubin from GF rat faeces was tested on faeces from conventional (CONV) rats. From these preparations, no ethyl anthranilate azopigments were formed, thus indicating that faeces from CONV rats is devoid of conjugated bilirubin.

Animals↗
PubMed1984

Deconjugation of bilirubin conjugates and urobilin formation by conventionalized germ-free rats.

The amounts of conjugated bilirubin and urobilins/urobilinogen were determined semiquantitatively in faeces of germ-free (GF) rats during GF condition and after conventionalization by oral administration of faeces suspension from conventional (CONV) rats. The amount of bilirubin conjugates, detected as their ethyl anthranilate azopigments, decreased rapidly 1 day after conventionalization. Thin-layer chromatography analysis of the corresponding faecal azopigment preparations showed that some azopigments started to disappear a few days after the conventionalization, indicating that their corresponding bilirubin conjugates were deconjugated by the bacteria in the intestine. On day 21 after conventionalization, only two azopigments were detected, namely the unconjugated and glucuronic acid conjugated dipyrroles of bilirubin, respectively, thus indicating the presence of only one bilirubin conjugate, the monoglucuronide. After 69 days no azopigments could be detected, indicating the total absence of conjugated bilirubin in these faeces samples. No urobilins were detected in faeces of the rats during their GF state, but these metabolites appeared in faeces one day after conventionalization and increased during a few days to a CONV level.

Animals↗
PubMed1984

Scanning and transmission electron microscopy of the phagocytosis of Treponema denticola and Escherichia coli by human neutrophils in vitro.

In the present in vitro study, scanning and transmission electron microscopy demonstrated that human neutrophils are able to phagocytize Treponema denticola cells. Two major modes of particle engulfment were detected, both of which seemed unaffected by opsonization or atmosphere (aerobic or anaerobic). The occasional finding of rather intact treponemes as long as 2 h after onset of the phagocytosis experiment, suggested that digestion could be a relatively slow process. Expulsion of digested material from the phagolysosomes to the extracellular space seemed to occur via channel-like structures in the neutrophil cytoplasm.

Escherichia coli↗
PubMed1984

Neutrophil phagocytosis of treponema denticola as indicated by extracellular release of lactoferrin.

Lysosomal enzyme release from viable human neutrophils occurs during phagocytic activity in vivo. Phagocytosis of a strain of T. denticola, an oral spirochete, was indicated by the finding of lactoferrin in the extracellular medium of neutrophils challenged with this organism. The extracellular release of lactoferrin was dependent on duration of bacterial challenge, but peak concentration appeared at a later stage than seen in phagocytosis experiments with Escherichia coli, which served as a control. Neutrophil phagocytosis of T. denticola may be of importance as a defence factor in periodontal disease.

Escherichia coli↗
PubMed1984

Phagocytosis, peritoneal influx, and enzyme activities in peritoneal macrophages from germfree, conventional, and ex-germfree mice.

Peritoneal macrophages from germfree mice showed a higher basic activity of lysosomal enzymes than did macrophages from conventional mice, whereas oil-induced peritoneal influx, induction of lysosomal enzymes, and phagocytosis via the C3b receptor after endotoxin stimulation were reduced or absent. After germfree mice had been housed with conventional mice for 1 week, peritoneal influx and C3b receptor-mediated phagocytosis reached normal levels; after 4 weeks, enzyme activities also reached normal levels.

Acid Phosphatase↗
PubMed1984

A possible role of intestinal mucin in the pathophysiology of intestinal strangulation obstruction. Consequences of tracing a clinical observation.

In intestinal strangulation obstruction, the pathophysiology is created by factors deriving from the host as well as from the intestinal flora. This article has focused upon the importance of one host-derived factor, i.e. intestinal mucin. Based upon a long series of in vitro and in vivo experiments utilizing germfree as well as conventional animals, it is concluded that intestinal mucin plays a major role in triggering a pathological plasma proteolysis, thereby interacting with microbial products (as endotoxin) in creating the whole variety of serious symptoms found in this situation.

Animals↗
PubMed1984

Comparison of bypass and resection of the small intestine in germfree rats.

Germfree rats were subjected to: (1) 90% jejunoileal resection (15 rats) or (2) 90% end-to-side jejunoileal bypass (20 rats). The mortality rate was 67 and 75%, respectively, which is markedly higher than after the same types of operation in conventional rats. Late mortality occurred only in the bypass group. Possible reasons for the high mortality rate are discussed. 5 rats in each group survived and were followed up for 6-12 weeks. At autopsy, the liver was normal, and except for lower serum concentration of albumin in the operated rats, the other liver function tests were normal. There did not seem to be any difference in body weight between the two groups of surviving rats which may indicate that the intestinal microflora is an important factor in causing the difference in body weight after resection and bypass of the small intestine in conventional rats. The number of surviving rats was small, however, and further studies are therefore necessary to give a definite answer to this question.

Animals↗
PubMed1984

Short-chain fatty acids in the proximal gastrointestinal tract of healthy subjects.

The total concentration of short-chain fatty acids (SCFAs) in healthy subjects, measured by gas chromatography, was in saliva and jejunal aspirates (n = 6) (median (range] 4480 (2780-9940) mumol/l and 265 (185-1470) mumol/l and in gastric and duodenal aspirates (n = 7) 719 (425-1770) mumol/l and 480 (137-778) mumol/l, respectively. Acetic and propionic acid accounted for 85% and 11%, respectively, and i-butyric, n-butyric, and i-valeric for less than 2% each in jejunal aspirates. A very similar relative distribution was present also in saliva and gastric and duodenal aspirates, essentially different from that of feces. Through anaerobic culturing from jejunum, 10(3) to 10(8) bacteria/ml was obtained; there was no correlation between the log number of bacteria and the SCFAs concentration before and after ingestion of sucrose. Swallowed exogenous radiolabeled propionate was partly recovered in the jejunum. The findings indicate that the SCFAs recovered from the jejunum in healthy subjects are mainly produced in the mouth and swallowed with the saliva.

Adult↗