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Biomedical subjects

T Midtvedt

Publications and source records attributed to T Midtvedt.

At least 109 records · Page 6Linked to original sources
PubMed1989

Short-chain fatty acids and other intestinal microflora-associated characteristics in faeces of patients with severe B-cell immunodeficiency.

The intestinal microflora of 18 patients with severe B-cell immunodeficiency was studied by determination of short-chain fatty acids (SCFAs) and other intestinal microflora-associated characteristics in the faeces. Glucose-hydrogen (H2) breath test was also performed. The results were within normal values in most of the patients, indicating no major pathologic changes in the intestinal bacterial microflora. These findings do not indicate any important role of the mucosa-associated B-cell system in the regulation of the composition and metabolic activity of the intestinal microflora.

Adolescent↗
PubMed1989

[Preventive antibiotics in elective colorectal surgery].

At least every third patient undergoing elective colorectal surgery without antibiotic cover will develop one or more postoperative infectious complications. Using appropriate antimicrobial prophylaxis with agents effective against both aerobe and anaerobe microorganisms less than 4 per cent of the patients will have such problems. Systemic (i.v.) prophylaxis started immediately before or at induction of anaesthesia is the preferred method, giving maximal tissue concentrations of the agents during the contamination process. Short term prophylaxis, at least as effective as 5 days prophylaxis, will reduce toxicity, cost and resistance problems. Using agents with long half-lives (for instance doxycycline and tinidazole) single-dose prophylaxis is sufficient. Clinical resistance problems or reduced efficacy could not be demonstrated even after 10 years routine use of these agents in prophylaxis. Antibiotics necessary for treatment of serious infections should not be used in routine prophylaxis. Nitroimidazoles (metronidazole, tinidazole) represent an exception since development of resistance to these agents is extremely rare.

Anti-Bacterial Agents↗
PubMed1988

In vivo formation of omega-oxidized metabolites of leukotriene C4 in the rat.

[3H8]Leukotriene C4 was administered to germfree rats and to conventional rats having a bile duct cannula. Several radioactive metabolites were isolated. Two polar biliary metabolites from conventional rats were identified as N-acetyl-omega-carboxy-leukotriene E4 and N-acetyl-omega-hydroxy-leukotriene E4. A polar fecal metabolite from germfree rats was found to be N-acetyl-omega-carboxy-leukotriene E4. Chemical identities were established using UV spectroscopy and cochromatographies with authentic compounds in several HPLC systems. The fecal metabolite was further characterized by reductive desulfurization followed by gas-liquid-radiochromatography. The yield of the two biliary metabolites was 5% of the administered tritium after three hours and the yield of fecal N-acetyl-omega-carboxy-leukotriene E4 was 3.5% after three days.

Animals↗
PubMed1988

The role of the intestinal microflora in the formation of mutagenic metabolites from the carcinogenic air pollutant 2-nitrofluorene.

After a single oral dose of 2-nitro[9-14C]fluorene (NF) to germfree and conventional rats, radioactivity with associated mutagenic activity was rapidly excreted in both urine and feces. The mutagenicity excreted from germfree animals exceeded the mutagenicity excreted from conventional animals. Absence of the microflora resulted in lack of nitroreduction and excreted metabolites from germfree rats were mono- or dihydroxylated nitrofluorenes, as assessed by liquid chromatography/mass spectrometry (LC/MS). These hydroxy-NFs were associated with the high direct-acting mutagenicity that was excreted in germfree animals. Only traces of NF were found in urine from germfree rats and no NF was detected in urine from conventional animals. Thus, in contrast to a number of reports on other mutagenic compounds, these results would tend to indicate that the intestinal microflora causes a reduced excretion of mutagenic metabolites of NF.

Air Pollutants↗
PubMed1988

Carbonic anhydrase isoenzymes in the caecum and colon of normal and germ-free rats.

Histochemical and immunocytochemical methods were used to study the presence of carbonic anhydrase (CA) isoenzymes in the caecum and colon of normal and germ-free rats. Very high enzyme activity was demonstrated by histochemistry in the caecum and proximal colon of normal rats, while the activity decreased in the distal colon. Very strong immunostaining for the isoenzyme CA I was found in the cytoplasm of surface cells and upper gland cells in the caecum and colon of normal rats. In the distal colon the staining was less intense with a marked cell-to-cell variation. Ca II was found in the apical (luminal) cell region of the surface epithelium in all regions. Ca III was possibly present in small amounts, but this could not be judged with certainty. There was no difference in carbonic anhydrase between normal and germ-free rats (except for less staining of the mucosal capillaries in germ-free animals). Therefore, our data give no support to the hypothesis that CA I participates in the absorption of microbial fermentation products. The location of CA II in the apical cell region suggests a role for this isoenzyme in regulation of the microclimate close to the epithelial cells.

Animals↗
PubMed1988

Reconstitution of the gastrointestinal microflora of lactobacillus-free mice.

A colony of mice that do not harbor lactobacilli in their digestive tracts but whose intestinal microflora is otherwise functionally similar to that of conventional animals was derived. Methods used to reconstitute the intestinal microflora of the mice included inoculation of the animals with cultures of specific microbes, noncultivable microbes attached to epithelial cells, and cecal contents from conventional mice treated with chloramphenicol. Twenty-six microflora-associated characteristics were monitored by using relatively simple tests to determine the microflora status of the mice.

Animals↗
PubMed1988

Comparison of tinidazole given as a single dose and on 2 consecutive days for the treatment of nonspecific bacterial vaginosis.

Nonspecific bacterial vaginosis, defined as the presence of clue cells, was treated in a randomized, double-blind study with (1) tinidazole 2 g as a single dose (82 patients), (2) tinidazole 2 g on 2 consecutive days (84 patients), and (3) with placebo (81 patients). The cure rates, both clue cells and Gardnerella vaginalis absent, were 51, 74 and 4%, respectively. A closer clinical and microbiological evaluation showed the 2-day regimen to be superior.

Adult↗
PubMed1988

Total parenteral nutrition and the function of the intestinal microflora in Crohn's disease.

The effect of total parenteral nutrition (TPN) on the following six intestinal microflora-associated characteristics (MACs) was studied in patients with Crohn's disease: faecal tryptic activity (FTA), formation of coprostanol, urobilinogen, and deoxycholic acid, and degradation of mucin and beta-aspartylglycine. The FTA showed high levels before TPN, in accordance with previous findings, and decreased during TPN. Formation of coprostanol, urobilinogen, and deoxycholic acid was reduced in some patients, whereas no changes were found in the mucin and beta-aspartylglycine degradation.

Adult↗
PubMed1988

Fundamentals in the prophylaxis of septic surgical complications.

An operation in which the colonic/rectal wall is opened represents a destruction of a complicated balance between the patient and his intestinal micro-flora, giving way for infective micro-organisms to become established. The surgeon should try to minimize the number of organisms reaching the operation field and reduce their possibilities of establishment. Some strategical and tactical guide-lines for achieving these goals are given.

Anti-Bacterial Agents↗
PubMed1987

Deconjugation of glycine-amidated bile salts does not occur in germfree rats.

After oral administration to germfree rats of cholyl-glycine-1-14C, deoxycholyl-glycine-1-14C and nor-ursocholyl-glycine-1-14C no significant amounts of 14CO2 are expired. This indicates that these bile salts are not significantly deamidated under physiological conditions in the rat organism outside the gastro-intestinal tract.

Administration, Oral↗
PubMed1987

Short-chain fatty acids in seven sterile thioglycollate media.

Short-chain fatty acids (SCFAs) were analysed by gas chromatography in 7 sterile fluid thioglycollate media. The total SCFA concentration varied from 250 mumol/l to 1720 mumol/l. Acetic acid (52.0%-91.3% of total SCFA concentration) and n-butyric acid (5.8%-48.0% of total concentration) were the main acids in all sterile media; low concentrations of propionic, isobutyric, isovaleric, and n-valeric acid were present in most media. In studies of bacterial metabolism, or when analyses of SCFAs are used for identification of bacteria, testing of the sterile medium is necessary.

Chromatography, Gas↗
PubMed1987

In vitro activity of ceftazidime, cefotaxime and gentamicin against 11,521 clinical isolates of bacteria.

The in vitro activity of ceftazidime has been compared with those of another third-generation cephalosporin, cefotaxime, and the aminocyclitol aminoglycoside, gentamicin. A total of 11,521 clinical isolates of aerobic bacteria were employed, and an agar diffusion method was used for sensitivity testing. The MIC-values were calculated from regression lines. The mean inhibition zones for ceftazidime against Gram-positive organisms were significantly less than those against Gram-negative isolates (23 mm vs. 33 mm, p less than 0.0001). Cefotaxime inhibited 74.0%, gentamicin 66.3% and ceftazidime 20.4% of the Gram-positive isolates at a concentration of less than or equal to 2 mg/ml. Ceftazidime and cefotaxime were equally active against fermentative Gram-negative rods, inhibiting 92.7% of each of these isolates at 2 mg/l. Against Ps. aeruginosa, ceftazidime (MIC90 2.2 mg/l) was found to be almost as active as gentamicin (MIC90 1.2 mg/l), and far more active than cefotaxime (MIC90 434 mg/l). Gentamicin was the most active agent against Acinetobacter sp. (MIC90 6.0 mg/l), followed by ceftazidime (MIC90 18 mg/l) and cefotaxime (MIC90 83 mg/l).

Bacteria, Aerobic↗
PubMed1987

Establishment of a biochemically active intestinal ecosystem in ex-germfree rats.

A time course study for the establishment of some biochemical microbial intestinal functions was undertaken in ex-germfree rats conventionalized, i.e., colonized with conventional flora, in three different ways: untreated (group 1); contact with visitor rats (group 2); inoculated with intestinal contents from conventional rats (group 3). The first two groups of rats were inoculated with the intestinal contents from conventional rats after being out of the germfree isolators for 4 weeks. The biochemical parameters studied were degradation of mucin, inactivation of tryptic activity, conversion of cholesterol to coprostanol and of bilirubin to urobilinogen, degradation of beta-aspartylglycine, and formation of short-chain fatty acids. The results showed that the way in which the microbes were introduced and the microbial biochemical functions themselves were of importance. In several cases, social contacts, i.e., contact with visitor rats, were just as effective for the functionally adequate establishment of microbial intestinal functions as was inoculation with intestinal contents from conventional rats. Some of the biochemical parameters studied were established after a few days, whereas the establishment of others was markedly delayed. When inoculated after 4 weeks, all rats in the first two groups were colonized with conventional flora within 1 week. The results indicate that the model system described is suitable when studying buildup mechanisms in intestinal ecosystem(s).

Animals↗
PubMed1987

Influence of ofloxacin on the faecal flora.

In a continuing, Norwegian-Swedish collaborative study, the effects of several antimicrobials upon intestinal biochemical microflora-associated characteristics are being investigated. In the present study, 7 healthy volunteers were given ofloxacin 200mg bid for 6 days. Faecal sampling was performed twice before, on days 3 and 6 during treatment, and weekly to monthly afterwards. Blood sampling was performed on day 6 during treatment. The concentrations of ofloxacin were measured in faeces and serum on day 6. Additionally, the following microflora-associated characteristics were studied in all the faecal samples: presence of short chain fatty acids, absence of beta-aspartylglycine, production of coprostanol, formation of urobilinogen, inactivation of tryptic activity and breakdown of mucin. The mean concentrations of ofloxacin in faeces and serum were 44.0 mg/kg and 2.1 mg/L, respectively. In contrast to most of the other antimicrobials so far tested, ofloxacin exerted almost no influence upon the microflora-associated characteristics investigated.

Adult↗
PubMed1987

Intestinal bacteria and rheumatic disease.

The striking clinical and pathological similarities between certain naturally occurring infectious diseases in animal species and those of some human rheumatic diseases, such as rheumatoid arthritis (RA), have stimulated the search for a microbial etiology of the latter syndrome. A long series of microbial species, including aerobic and anaerobic intestinal bacteria, mycoplasma and several viruses have been put into focus. Most often, however, an initially positive report has been followed by several reports denying an etiological role of the microbial species in focus. However, the concept of a microbial trigger in the etiology and symptomatology of RA is still a subject of intense debate. Recent results have indicated a reversed effect of gram-positive vs. gram-negative intestinal bacteria on adjuvant-induced arthritis in germfree rats and microbial peptidoglycans have been shown to play a major role in this experimental model. It has been shown that the intestinal flora may include bacteria containing antigenic determinant(s) cross-reacting with some markers within the HLA-system. The intestinal flora may also influence upon several digestive and absorptive functions and thereby acting upon parameters of importance in the development of rheumatic disease.

Animals↗
PubMed1987

The influence of high and low pressure on phagocytosis of Escherichia coli by human neutrophils in vitro.

Human polymorphonuclear neutrophils were exposed to high (4 atm) and low (0.4 atm) pressures in vitro before and during phagocytosis of radiolabelled Escherichia coli. Preexposure of the neutrophils to high pressure before phagocytosis did not influence uptake. However, when phagocytosis took place at 4 atm the uptake of bacteria opsonized by active serum and IgG was significantly depressed. On the other hand, uptake in the presence of heat-inactivated serum or albumin and uptake of non-opsonized E. coli was not changed at high pressure. The results suggest an influence on uptake mechanisms related to receptors in the cell membrane. When the neutrophils were exposed to hypobaric pressure both before and during phagocytosis, the uptake of nonopsonized E. coli was slightly depressed. However, neither preexposure nor exposure during phagocytosis was sufficient alone to elicit this inhibiting effect. The uptake of E. coli opsonized by active serum or IgG was not influenced by low pressure.

Atmospheric Pressure↗