PubMed Health⌕ Search

Biomedical subjects

T Midtvedt

Publications and source records attributed to T Midtvedt.

At least 19 recordsLinked to original sources
PubMed1992

Cytokine responsiveness in germfree and conventional NMRI mice.

We have investigated the proliferative response of thymocytes from different mouse strains to cytokines in vitro. Interleukin 2 (IL-2), IL-4 and IL-7 induced proliferation of thymocytes from NMRI/KI (a locally bred NMRI mouse strain), NMRI/H ('traditional' NMRI mice), C3H/HeJ and C3H/HeN mice. NMRI/KI thymocytes showed the most prominent proliferation in response to IL-1 alpha and IL-1 beta. IL-3, IL-5, IL-6, IL-8, IL-10, tumour necrosis factor alpha (TNF-alpha), interferon gamma (IFN-gamma), inhibin and lipopolysaccharide (LPS) induced no thymocyte proliferation. Germfree NMRI/KI mouse thymocytes showed a significantly lower proliferation in response to IL-1 alpha and IL-1 beta than conventional mice. Rat tissues, previously shown to contain lymphocyte activating factors (LAFs), were also tested. Skin, tongue, esophagus, proventricular stomach, testis and placenta were all positive in the LAF assay utilizing NMRI/KI thymocytes, whereas none of the tissue extracts could induce proliferation in NMRI/H thymocytes. The higher cytokine responsiveness in conventional mice compared with germfree might suggest that exposure to microflora induces a higher state of activation of the immune system. The LAF assay, utilizing NMRI/KI thymocytes, is a highly sensitive IL-1 bioassay with a detection level of 1 pg/ml for IL-1 beta and 2 pg/ml for IL-1 alpha. The specificity of the assay is increased by utilizing NMRI/H mice to exclude the presence of IL-2, IL-4 and IL-7.

Animals↗
PubMed1979

Comparison of peritoneal macrophages from germfree and conventional mice.

Morphology, lysosomal enzyme activities, and phagocytosis via immunological receptors were tested in peritoneal macrophages from germfree and conventional mice. Nonstimulated macrophages from germfree mice showed less spreading and were more easily detached when seeded on glass than conventional macrophages. The activities of the lysosomal acid phosphatase and cathepsin D were similar in the two cell groups, whereas beta-glucuronidase showed higher activity in macrophages from germfree mice. F(c) receptor-mediated phagocytosis of opsonized sheep erythrocytes was equally effective in germfree and conventional macrophages, and both cell types attached but did not internalize erythrocytes via the C(3)b receptor. Intraperitoneal injections of mineral oil caused a significantly higher influx of macrophages in conventional mice than in germfree mice, whereas the influx of polymorphonuclear cells was enhanced in both animals. Stimulation in vivo with oil or Escherichia coli endotoxin increased cell size, spreading ability, membrane ruffling, and lysosomal enzyme activities in macrophages from both conventional and germfree mice. The Fc-mediated phagocytosis was not influenced by stimulation, whereas the capacity to internalize via C(3)b receptor was triggered in macrophages from conventional mice, but not in corresponding cells from germfree mice. Similar results were obtained after stimulation with endotoxin in vitro. Culture in fetal calf serum for 72 h caused intracellular rises in all three enzyme activities tested in macrophages from conventional mice, whereas only the activity of acid phosphatase was increased in macrophages from germfree mice. Stimulation with zymosan in vitro caused selective release of lysosomal enzyme activity in macrophages from both animal groups. We conclude that peritoneal macrophages from germfree mice share several properties with cells from conventional mice, however, unstimulated beta-glucuronidase activity was increased, whereas spreading on glass, chemotactic response, in vitro induction of lysosomal enzymes, and the capacity to internalize via the C(3)b receptor after stimulation were reduced or absent.

Acid Phosphatase↗
PubMed1979

A comparison of the in vitro activity of a new cephalosporin, cefuroxime, and cephalothin against 810 clinical isolates.

810 strains of eight species: Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus faecalis, Escherichia coli, Klebsiella sp, Enterobacter sp, Proteus mirabilis and Proteus vulgaris, were tested by the disc diffusion method against cephalothin and cefuroxime. The activity of the two drugs was comparable to S aureus and S epidermidis, and a little in favour of cefuroxime regarding S faecalis. Cefuroxime turned out to be superior to cephalothin against the gram negative rods investigated. This pattern was most pronounced when Enterobacter was investigated.

Bacteria↗
PubMed1979

Sensitivity patterns of bacteria and antibiotic usage at the National Hospital of Norway in 1976 and 1978.

During the first three months of 1976 and 1978 the sensitivity patterns of bacteria and the antibiotic usage at the National Hospital of Norway was recorded. The computerized results showed that bacteria isolated at the department of pediatrics was more resistant to penicillins. Isolates from two other departments did not differ very much in their sensitivity patterns. Comparing the sensitivity patterns, a tendency of increased sensitivity to antibiotics from 1976 to 1978 was seen. Exception was the increasing resistance to gentamicin. Furthermore, tobramycin was found less effective than gentamicin on our isolates. The antibiotics most widely used at the hospital are the penicillins which account for more than 50 per cent of the usage. From 1976 to 1978 the usage of antibiotics increased about 30 per cent. A more extensive use of penicillin V and G, and sulfamethoxazole/trimethoprim was responsible for most of the increase. No clear cut relationship between the antibiotic usage and the changes in sensitivity patterns of the bacteria from 1976 to 1978 was seen. Our work confirms, the usefulness of using "daily defined doses", as recommended by WHO, for estimating the antibiotic usage in a hospital.

Anti-Bacterial Agents↗
PubMed1978

Effect of rat intestinal glycoprotein on complement lytic activity of 32P-labelled Escherichia coli.

Evidence for complement activation by an intestinal glycoprotein fraction from germfree rats is presented. The lowering effect on human serum bactericidal activity of E. coli was 28% for the intestinal glycoprotein fraction, 31% for zymosan, and 25% for inulin, while the lowering effect on conventional rat serum bactericidal activity was 65%, 53% and 21%, respectively. 32P-releasing activity of serum from germfree rats and from man on labelled E. coli amounted to 8% and 28%, respectively, of the release exerted by serum from conventional rats.

Animals↗
PubMed1978

Endoscopy-related bacteremia.

A prospective study was undertaken to investigate the frequency of bacteremia after endoscopy of the gastrointestinal tract. In one out of 100 patients undergoing gastroscopy and in one out of 25 patients undergoing coloscopy, positive blood cultures could be demonstrated. In both cases anaerobe lactobacilli were recovered. No bacteremia was demonstrated in 25 patients undergoing endoscopic retrograde cholangiopancreatography (ERCP).

Cholangiography↗
PubMed1977

A glycoprotein of high molecular weight in the urine of germ-free rats.

A carbohydrate-rich glycoprotein fraction was obtained by purification of the non-dialysable material of germ-free rat urine. This procedure involved proteolytic digestion with pronase, presipitation of the acidic glycoprotein with cetyltrimethyl-ammonium bromide (CTAB), and chromatography on DEAE-Sephadex and finally on Sepharose 4B from which it was partly excluded. The purified glycoprotein contained fucose (10.1%), galactose (12.2%).N-acetylglucosamine (16.6%), N-acetylgalactosamine (19.8%), sialic acid (11.9%), and sulphate ester groups (0.7%). The amino acid content was 19%, threonine, serine and proline being the predominating amino acids. Gel electrophoresis and gel chromatography revealed a pronounced poly-dispersity of the material. Treatment of the glycoprotein with alkali in the presence of borohydride led to partial degradation of the polymer with the formation of fragments containing N-acetylgalactosaminitol. The chemical properties of the purified glycoprotein are characteristic of a mucin. The presence of this glycoprotein could not be demonstrated in conventional rat urine.

Amino Acids↗
PubMed1977

Origin of intestinal beta-glucuronidase in germfree, monocontaminated and conventional rats.

The intestinal beta-glucoronidase was studied in germfree, monocontaminated and conventional rats. The greater part of the beta-glucuronidase of the caecum and the large intestine of the contaminated animals was of bacterial origin. No bacterial beta-glucuronidase was found in the small intestine. Monocontamination with Escherichia coli gave activities corresponding to those of the conventional rats, whereas content from the caecum and the large intestine of the rats monocontaminated with Streptococcus pyogenes showed an activity approximately 10 per cent of that of the conventional rats.

Animals↗
PubMed1977

The effect of eight antibacterial agents on the phagocytosis of 32P-labelled Escherichia coli by rat polymorphonuclear cells.

Using 32P-labelled Escherichia coli, the effect of 8 antibacterial agents on the ability of rat polymorphonuclear cells to ingest the labelled bacteria was studied with and without serum present during the ingestion phase. No impairment of ingestion was observed when testing gentamicin, cephalothin and trimethoprim. High doses of oxytetracycline, doxycycline, colistin, erythromycin and chloramphenicol seemed to impair ingestion. The effect was most pronounced when applying 100 mug/ml of doxycycline: the ingestive capability was reduced to 25% without serum and 24% with serum present compared to untreated controls. 83 mug/ml of colistin reduced theingestion to 39% without serum present, this effect being totally eliminated when serum was present during the ingestion phase.

Anti-Bacterial Agents↗
PubMed1976

A computer system for handling data from bacterial sensitivity testing.

A computer system for handling data collected from antibiotic sensitivity testing of clinical bacterial isolates is described. The system allows a rapid handling of the information collected, supplying the ward and laboratory with cummulative data on each patient. The bacteriologist and the clinician are thus suitably armed when creating a rational antibiotic therapy.

Computers↗