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Biomedical subjects

R Andersson

Publications and source records attributed to R Andersson.

At least 181 records · Page 10Linked to original sources
PubMed1994

Obstructive jaundice impairs reticuloendothelial function and promotes bacterial translocation in the rat.

Septic complications and renal insufficiency following biliary tract surgery are frequently seen in patients with obstructive jaundice. The precise mechanisms for understanding the susceptibility of the jaundiced patients to sepsis are, however, not clear. The present study aimed at investigating the influence of biliary obstruction on the reticuloendothelial function and bacterial translocation at various time intervals in the rat. Reticuloendothelial system (RES) function, as evaluated by measuring blood clearance of intravenously injected 125I-labeled Escherichia coli, and bacterial translocation were studied 3 days and 1, 2, and 3 weeks following either sham operation or common bile duct ligation (CBDL) and transection in the rat. RES function was significantly impaired and renal uptake of radiolabeled E. coli was significantly higher in jaundiced animals from Day 3 and on after CBDL (P < 0.01) concomitant with elevation of plasma levels of bilirubin and liver enzymes (P < 0.001) compared with their corresponding controls. The incidence of bacterial translocation 3 days and 1 and 2 weeks after biliary obstruction significantly increased (P < 0.05). We conclude that RES phagocytic function is impaired and the incidence of bacterial translocation is increased in jaundiced rats. These findings might contribute to explain the high susceptibility of postoperative septic complications and renal dysfunction in patients with obstructive jaundice.

Acute Kidney Injury↗
PubMed1994

Bacterial translocation after intraperitoneal implantation of rubber fragments in the splenectomized rat.

The aim of the present study was to determine the influence of splenectomy on the incidence of enteric bacterial translocation in rats with intraperitoneal rubber drain implantation. Male Sprague-Dawley rats (250-300 g) underwent splenectomy or sham operation 7 days prior to the intraperitoneal implantation of rubber drain fragments (7 cm2). Bacterial translocation was measured 2 days after rubber drain implantation. The incidence of bacterial translocation was significantly higher in the group with intraperitoneal rubber drain implantation plus sham splenectomy than in the groups with sham splenectomy plus sham implantation, splenectomy plus sham implantation or splenectomy plus rubber drain implantation. An increase in ileal permeability of 125I-human serum albumin was induced by intraperitoneal rubber drain implantation and ameliorated by splenectomy. Splenectomy also improved the impaired intestinal motility induced by intraperitoneal rubber drain implantation. Histological examination revealed a preserved normal mucosal architecture in splenectomized rats. Thus, splenectomy reduced the rate of enteric bacterial translocation induced by intraperitoneal biomaterial implantation.

Animals↗
PubMed1994

B- and T-cell responses in congenic mice to repeat sequences of the malaria antigen Pf332: effects of the number of repeats.

The Plasmodium falciparum antigen Pf332 comprises degenerated 11-amino-acid repeats with regularly spaced pairs of glutamic acid. Epitopes formed by such repeats are recognized by polyclonal and monoclonal antibodies that interfere with the life cycle of the blood stages of the malaria parasite. In order to study the immunogenicity of one such Pf332 repeat sequence (SVTEEIAEEDK), fusion proteins containing ZZ (two IgG binding domains of staphylococcal protein A) and dimers, trimers or tetramers of the malarial sequence were injected into mice. To analyse possible major histocompatibility complex class II restrictions of the immune response, mice of different H-2 haplotypes were used. A significant antibody response was elicited by administration of all the three fusion proteins in mice expressing the I-Ak allele (B10.BR, B10.A(2R) and B10.A(4R)) whereas B10 and C57BL/6 (H-2b) mice were low responders. In comparison, B10.D2 (H-2d) mice were low responders to fusion proteins with 2 or 3 repeats but responded well to the protein containing 4 repeats. Lymph node cells from B10.BR (H-2k) mice, primed in vivo with ZZ-fusion proteins containing either 2 or 4 repeats, proliferated in vitro in response to repeat sequences fused to ZZ or to an unrelated fusion partner, as well as to a synthetic peptide containing less than two repeats. In contrast, a response of lymph node cells from B10.D2 (H-2d) mice was only obtained when a fusion protein containing 4 repeats was used both for in vivo priming and in vitro restimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Nonrandom T-cell receptor J beta usage pattern in human CD4+ and CD8+ peripheral T cells.

Association frequencies of TCR J beta gene segments with six V beta families (V beta 3, 6.1-3, 8, 9, 12, and 18) were analyzed in T-cell populations obtained from healthy blood donors. The six selected V beta families are located at various chromosomal positions relative to other recombinatorial elements (D beta, J beta, C beta). We report here that in CD4+ as well as CD8+ T-cell subsets, all 13 J beta gene segments were used in combination with all the V beta s tested and that no correlation between the genomic position of the individual V beta s and J beta gene segment usage was observed. J beta gene segment usage was found to be nonrandom in general, with J beta 2.7 and J beta 2.4 exhibiting highest and lowest frequency of utilization, respectively. J beta family 2 was used more frequently than J beta family 1 by the two T-cell subsets. Some individual J beta gene segments were skewed toward either CD4+ or CD8+ T cells. Thus, J beta 1.3 and J beta 1.6 were consistently biased toward expression in CD4+ T cells. In contrast, when combined with V beta 8 or V beta 9, J beta 2.1 results were skewed dramatically toward expression in CD8+ T cells. We also found 70 cases of expanded individual V beta/J beta associations in a total of 1092 investigated combinations, 62 of which were confined to the CD8+ T-cell populations. CD8+ T-cell populations are thus much more likely to contain TCR V beta/J beta-restricted expansions than CD4+ T cells.

Blotting, Southern↗
PubMed1994

Inhibition of bacterial translocation in obstructive jaundice by muramyl tripeptide phosphatidylethanolamine in the rat.

Obstructive jaundice is frequently associated with septic complications and enteric bacteria have been isolated from both the infectious focus and bile in jaundiced patients. The present study aimed to evaluate bacterial translocation and the influence of a macrophage-stimulant (muramyl tripeptide phosphatidylethanolamine) on bacterial translocation in obstructive jaundice. Male Sprague-Dawley rats were subjected to sham operation (n = 10) or common bile-duct ligation and transection (n = 35). Two weeks later, jaundiced animals received either physiological saline (n = 15), muramyl tripeptide phosphatidylethanolamine liposomes (n = 10) or placebo (empty) liposomes (n = 10) orally, while sham-operated rats received physiological saline, 48 h prior to evaluation of enteric bacterial translocation. Blood, bile and caecal contents were collected and cultured aerobically and anaerobically, as were tissue samples from the liver, spleen and mesenteric lymph nodes. Positive mesenteric lymph node cultures in animals with jaundice + saline (7/15; 47%) and jaundice + placebo liposomes (4/10; 40%) significantly differed (p < 0.05) from sham-operated animals (1/10; 10%) and muramyl tripeptide phosphatidylethanolamine treated animals (0/10). Caecal counts (CFU/g) of Escherichia coli, Lactobacilli and aerobic and microaerobic bacteria did not differ statistically among the groups, although the number of E. coli tended to be higher in jaundiced animals. Thus, liposomal muramyl tripeptide phosphatidylethanolamine inhibits bacterial translocation, probably by activating mucosal macrophages and enhancing reticuloendothelial system function in rats with biliary obstruction.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1994

Formation of DNA adducts by the food mutagen 2-amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (4,8-DiMeIQx) in vitro and in vivo. Identification of a N2-(2'-deoxyguanosin-8-yl)-4,8-DiMeIQx adduct.

The covalent binding of the mutagenic N2-hydroxy metabolite of the food mutagen 2-amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (4,8-DiMeIQx) to 2'-deoxynucleosides and DNA was investigated in vitro and in vivo. N2-Hydroxy-4,8-DiMeIQx reacted to a small extent spontaneously with 2-deoxyguanosine. However, acetylation of N2-hydroxy-4,8-DiMeIQx with acetic anhydride to form the N2-acetoxy derivative prior to reaction with 2-deoxyguanosine resulted in much higher yield of adduct. N2-Acetoxy-4,8-DiMeIQx did not form adducts with 2'-deoxyadenosine, 2'-deoxycytidine or 2'-deoxythymidine. The adduct formed between the N2-OH metabolite of 4,8-DiMeIQx and 2-deoxyguanosine was analysed by mass spectrometry and NMR spectroscopy and the structure of the adduct was shown to be N2-(2'-deoxyguanosin-8-yl)-4,8-DiMeIQx. N2-Acetoxy-4,8-DiMeIQx reacted with calf thymus DNA and formed a covalently bound 4,8-DiMeIQx residue, which could not be removed by repeated precipitations or solvent extractions. The 4,8-DiMeIQx-DNA was hydrolysed enzymatically with nuclease P1/acid phosphatase and HPLC analysis showed that 70% of the bound mutagen was recovered as N2-(2'-deoxyguanosin-8-yl)-4,8-DiMeIQx. An additional minor adduct accounting for approximately 15% of the bound mutagen showed UV spectral characteristics similar to N2-(2'-deoxyguanosin-8-yl)-4,8-DiMeIQx and is probably an undigested oligomer. 32P-Postlabelling analysis of calf thymus DNA modified with 4,8-DiMeIQx in vitro and liver DNA from rats dosed with 50 mg/kg 4,8-DiMeIQx showed a similar adduct pattern. In both samples N2-(2'-deoxyguanosin-8-yl)-4,8-DiMeIQx accounted for 60-70% of the bound mutagen. Thus, these results show that 4,8-DiMeIQx similar to other heterocyclic amines form adducts with C-8 of guanine both in vitro and in vivo via its N2-OH metabolite.

Acetylation↗
PubMed1994

Promotion of Escherichia coli adherence to rubber slices by adsorbed fibronectin.

Biomaterial-associated infections are a problem in the use of endoprosthetic materials in the palliative treatment of malignant obstructive jaundice. Fibronectin has been reported to mediate adherence of bacteria to host tissue and biomaterials. Adsorption of fibronectin to rubber--representing material used for biliary drainage--and subsequent adherence of Escherichia coli strain PSS1 and E. coli strain NG7C (which binds to immobilised fibronectin) were investigated. Quantitative adsorption of fibronectin to rubber slices was studied with 125I-labelled, purified human plasma fibronectin. In buffer solutions, fibronectin showed a high affinity for rubber slices. Adherence of the E. coli strains to uncoated rubber slices was similar and was significantly inhibited by the presence of plasma components and bile. Adherence of E. coli PSS1 to fibronectin-coated slices was poor. In contrast, E. coli NG7C adhered efficiently to coated slices in proportion to the amount of adsorbed fibronectin; adherence was not reduced by the presence of albumin or bile, or the fibronectin-binding ligands gelatin, heparin and fibrinogen. However, pre-digestion of coated slices with trypsin significantly reduced adherence.

Adsorption↗
PubMed1994

Abdominal rubber drain piece aggravates intra-abdominal sepsis in the rat.

Biomaterials in the peritoneal cavity disrupt the physiology of the host and may cause bacterial translocation. The current study was performed to determine whether biomaterials exacerbate intra-abdominal infections. Adult male rats were divided into four groups: group 1, celiotomy+intraperitoneal (i.p.) saline; group 2, celiotomy+i.p. Escherichia coli (3 x 10(8) cfu); group 3, i.p. rubber+i.p. saline; and group 4, i.p. rubber+i.p. E. coli (3 x 10(8) cfu). Twelve h after the challenge, enteric bacterial translocation, bacterial population levels in the cecum and serum levels of IL-6 and TNF were measured. Bacterial translocation to mesenteric lymph nodes and the liver was observed in animals from groups 2 and 3, but significantly increased in group 4 with a concomitant elevation of serum levels of TNF and IL-6, as compared with group 1. Histological examination revealed a more pronounced inflammatory reaction in the peritoneum and distal ileum in group 4 than in groups 2 and 3. These results suggest that the presence of rubbers in the peritoneal cavity aggravates intra-abdominal sepsis.

Abdomen↗
PubMed1994

Plasma acetylsalicylic acid and salicylic acid levels during aspirin provocation in aspirin-sensitive subjects.

The ability of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) to inhibit the cyclo-oxygenase which catalyzes formation of prostaglandins appears to be central to the mechanisms involved in aspirin sensitivity. We have investigated whether the plasma levels of acetylsalicylic acid (ASA) and its main metabolite salicylic acid (SA) at the time of intolerance reactions correspond with the concentrations required for enzyme inhibition in vitro. Twelve aspirin-sensitive and 15 aspirin-tolerant subjects were followed during provocation with aspirin. ASA and SA concentrations in plasma were determined by HPLC. After oral provocation (up to 460 mg cumulative dose), the levels of ASA and SA in plasma were equivalent in aspirin-sensitive and aspirin-tolerant subjects. For the aspirin-sensitive subjects, at the time of adverse reaction, the concentration range was 2.9-33.3 microM for ASA and 18.1-245 microM for SA. Oral provocation with sodium salicylate yielding 10-fold higher SA levels did not elicit intolerance reactions. Statistically significantly lower levels of ASA and SA (P < or = 0.01) evoked airway obstruction, as compared with merely extrapulmonary symptoms. Bronchial absorption of aspirin was found after inhalation of lysine-aspirin and was comparable in asthmatic and nonasthmatic subjects. In three aspirin-sensitive subjects who developed airway obstruction, the plasma levels for ASA and SA were 0.9-2.6 microM and 0.0-6.7 microM, respectively. In conclusion, the plasma levels of ASA reached at the time of a positive reaction are of the magnitude known to inhibit cyclo-oxygenases. Neither differences in bioavailability of ASA nor the formation of SA seems to contribute to the aspirin-elicited reactions.

Administration, Oral↗
PubMed1994

Orally administered phospholipids inhibit abdominal rubber-drain-induced bacterial translocation in the rat.

In order to determine the influence of phospholipid on abdominal biomaterial-induced bacterial translocation (BT), phsophatidylcholine (PC) or phosphatidylinositol (PI) was administered orally or intraperitoneally in rats with intraperitoneal implantation of 7-cm2 rubber drain pieces. Two days after surgery, the incidence of translocation to mesenteric lymph nodes and liver significantly decreased, the adherence of 3H-labeled Escherichia coli to the ileal mucosa was significantly inhibited and the phagocytic and bactericidal capacity of peritoneal macrophages increased in animals with PC or PI administered orally, but not intraperitoneally, as compared with rats without phospholipid administration. Scanning electron microscopy revealed a coating layer on the surface of the intestinal mucosa in phospholipid-gavaged rats. Thus, the results in the present study imply that oral, but not intraperitoneal, PC of PI administration reduces enteric BT induced by intraperitoneal drain implantation.

Administration, Oral↗
PubMed1994

Giant cell arteritis. Epidemiology and treatment.

Giant cell arteritis (GCA) was considered a rare disease 50 years ago; however, it is now known to be an important and significant cause of morbidity and mortality in elderly people. GCA is a generalised arteritis, although the aetiology and pathogenesis of this disorder are poorly understood. It is likely that there are environmental or genetic factors that significantly influence the risk for the disease in different populations. Epidemiological studies have shown the highest incidence in Northern Europe and in Minnesota, US; which are populations of the same descent. Much lower incidence figures have been reported from more Southern regions of Europe and elsewhere. Possibly, the incidence of the disease is increasing as suggested by recent surveys. Glucocorticosteroids are the drugs of choice in all clinical types of GCA. Most studies have been performed with prednisolone. There is no general agreement concerning the initial dosage, but 10 to 40 mg/day is commonly recommended. After a few months the majority of patients can be treated with a low maintenance dosage of prednisolone 5 to 7.5 mg/day. Because of the low dosage required, the frequency of corticosteroid-related adverse effects is relatively low. The median duration of treatment is about 5 years. Nonsteroidal anti-inflammatory drugs, in contrast to corticosteroids, have no proven preventive effect on vascular complications of GCA, and cannot be recommended.

Adrenal Cortex Hormones↗
PubMed1994

Water-soluble ethylhydroxyethyl cellulose: a new agent against bacterial translocation from the gut after major liver resection.

BACKGROUND: Bacterial translocation from the gut to extraintestinal sites has been demonstrated as a mechanism explaining bacterial infectious complications after various insults. METHODS: To explore the potential therapeutic value of water-soluble ethylhydroxyethyl cellulose (EHEC). Its effects on macrophage phagocytic capacity, bacterial adherence on the intestinal surface, and bacterial growth were evaluated both in vivo and in vitro. RESULTS: Preoperative administration of EHEC reduced the incidence of bacterial translocation from the gut to mesenteric lymph nodes and blood and prevented overgrowth by enteric bacteria after 70% or 90% hepatectomy. Uptake of macrophages harvested from blood decreased after intravenous administration of EHEC. EHEC diminished the otherwise increased bacterial adherence on the intestinal surface induced by major liver resection. EHEC in bacterial cultures for over 1 h was capable of inhibiting bacterial growth and delaying bacterial DNA synthesis in vitro. CONCLUSIONS: The present study indicates that EHEC could be a potential agent for the prevention of gut-origin sepsis.

Animals↗
PubMed1994

Phospholipids prevent enteric bacterial translocation in the early stage of experimental acute liver failure in the rat.

BACKGROUND: Bacterial infections and bacteremia in acute liver failure may at least partly be attributed to translocation of enteric bacteria. Attempts to prevent or treat such infections by the use of antibiotics may instead result in overgrowth of surviving microbes. METHODS: In the present study, normal saline (1.5 ml/100 g body weight), phosphatidylcholine (1.5 ml/100 g body weight), and phosphatidylinositol (1.5 ml/100 g body weight) were orally administered by means of a gastric tube both 12 h and 30 min before operation. Effects of enteric administration of phospholipids on the prevention of enteric bacterial translocation, intestinal and mucosal mass, and enterocyte protein contents in acute liver failure induced by subtotal liver resection in the rat were evaluated. RESULTS: The incidence of bacterial translocation increased significantly 2 and 4 h after 90% hepatectomy as compared with sham-operated animals. Enteric administration of phospholipids, however, significantly reduced the incidence of bacterial translocation after 90% hepatectomy. Phospholipid treatment prevented the postoperative decrease in intestinal mucosal mass and enterocyte protein content. CONCLUSIONS: Enteral administration of phospholipids thus seems to protect against translocation of enteric bacteria and prevent against a decrease in intestinal mucosal mass and enterocyte protein content after subtotal hepatectomy in the rat.

Animals↗
PubMed1994

The association between enteric bacterial overgrowth and gastrointestinal motility after subtotal liver resection or portal vein obstruction in rats.

OBJECTIVE: To test the hypothesis that intestinal motility is delayed after hepatectomy, which alters the ecology of the enteric microflora and contributes to the development of bacterial translocation from the gut. DESIGN: Open experimental study. SETTING: University department of surgery. MATERIAL: Adult male Sprague-Dawley rats (n = 6 in each group at each time point). INTERVENTIONS: Sham operation, 90% hepatectomy, and portal venous obstruction. MAIN OUTCOME MEASURES: Intestinal morphology, immunocytochemistry of the enteric nervous system, enteric bacterial growth in the small intestine and colon, and intestinal transit time. RESULTS: Intestinal transit was already delayed one hour after 90% hepatectomy, and histopathological alterations and overgrowth by Escherichia Coli had developed after two hours. There were significant differences in intestinal transit time between sham operated rats and those subjected to portal venous obstruction on the one hand, and those that underwent 90% hepatectomy on the other. There was no difference in intestinal transit time between rats with portal venous obstruction and the sham operated animals. CONCLUSION: Delayed intestinal transit after 90% hepatectomy may contribute to enteric bacterial overgrowth and thereby contribute to the development of bacterial translocation from the gut.

Animals↗
PubMed1994

Macrophage phagocytic dysfunction and reduced metabolic response in experimental obstructive jaundice.

OBJECTIVE: To investigate the metabolic response as measured by microcalorimetry and the phagocytic activity or peritoneal macrophages that had been harvested from jaundiced and normal rats and incubated with Escherichia coli in vitro. DESIGN: Open laboratory study. SETTING: University departments of surgery and immunology. MATERIAL: 12 Male Sprague-Dawley rats. INTERVENTIONS: Ligation and transsection of the common bile duct (n = 6) or sham operation (n = 6). MAIN OUTCOME MEASURES: Metabolic response (pW/cell) measured by microcalorimetry and phagocytic function assessed by light microscopy after Giemsa stain two weeks after operation. RESULTS: The mean (SEM) maximal metabolic response of macrophages and the metabolic rate one hour after inoculation with E coli were significantly reduced in jaundiced rats compared with controls (6.95 (1.95) compared with 27.39 (7.24), p = 0.005, and 5.50 (1.05) compared with 20.10 (3.35) p = 0.016, respectively) as were the number of E coli phagocytosed by macrophages harvested from jaundiced animals (p = 0.0002). CONCLUSION: The reduced metabolic response and phagocytosis of E coli by peritoneal macrophages in rats by biliary obstruction is a sign of depressed reticuloendothelial function. This mechanism may explain the high incidence of infective complications inpatients with obstructive jaundice.

Animals↗
PubMed1994

The role of septic complications in aortic aneurysm surgery.

Out of 229 patients operated due to abdominal aortic aneurysms, 51 (22.3%) had prolonged (> 120 hours) postoperative intensive care stay. The mortality rate in this group was 27% representing 46% of the total mortality. Twenty-five of these 51 patients had postoperative septic complications, meaning positive blood cultures. Clinically wound infections (11), acalculous cholecystitis (9), urinary tract infections (9), septicemia (6), and diffuse peritonitis or abdominal abscess were found (4). Reoperations, time for ventilatory support, incidence of renal failure and dialysis, gastrointestinal complications and mortality were all frequent in patients with septic postoperative complications as compared to those with non-septic complications, the latter mainly of cardiovascular origin. Signs of organ dysfunction should raise a suspicion of a septic complication and prompt insertion of diagnostic procedures and therapeutic interventions are necessary in order to minimize morbidity and mortality.

Abdominal Abscess↗