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Biomedical subjects

E A Carter

Publications and source records attributed to E A Carter.

At least 19 recordsLinked to original sources
PubMed1992

Ontogeny of class II MHC mRNA in the mouse small intestinal epithelium.

MHC Class II (Ia) and invariant chain cooperate in the presentation of exogenous antigen by antigen presenting cells to T-helper cells. Both glycoproteins have been identified in the small intestine of the mature mouse. In this study, we examine the ontogeny of mRNA for three molecules; (Ii31, Ii41 and I-A beta) in whole intestine and in isolated epithelial cells. When RNA from whole intestine was analysed in northern blots using cDNA probe, Ii31 mRNA was present in Day 10 mice and at each 5 day time point thereafter; Ii41 and I-A beta were not detected by this technique. To examine ontogeny of Ii chain mRNA in enterocytes, RNA was purified from an enriched population of epithelial cells isolated after systemic perfusion with 30 mM EDTA in Day 21 and Day 28 and adult mice. Ii chain mRNA was not detected until Day 28 by blot hybridization. Reverse transcription of mRNA and amplification of the resultant cDNA by PCR revealed Ii41 and I-A beta as well as Ii31. RNA from Day 21 epithelial cells required five additional amplification cycles to attain cDNA levels equivalent to those found in Day 28 cells for Ii chain, and 10 additional cycles for I-A beta. In conclusion, Ii31, Ii41 and I-A beta mRNA increase rapidly in the enterocyte after weaning.

Aging↗
PubMed1992

Effect of acute and chronic lipopolysaccharide (LPS) administration on reticuloendothelial system (RES) phagocytic activity in vivo.

The effect of injection or chronic infusion of lipopolysaccharide (LPS) into unanaesthetized rats on the distribution of [99Tcm-]SC has been determined. At a dose of 2.5 mg/kg, LPS injection caused a marked alteration in the distribution of the radiolabelled material, with more uptake being achieved in the lung while less was taken up by the spleen. Kidney and liver uptake were also changed. Chronic infusion of LPS at a similar dose (3 mg/kg in 24 h) caused a marked increase in the uptake of the radioactive material by the lung only. These data are consistent with a working hypothesis that the alterations in RES phagocytic activity of the lung observed in rats subjected to burn trauma could be related in part to LPS, either coming as a bolus, or being continuously presented.

Animals↗
PubMed1992

Increased transcellular permeability of rat small intestine after thermal injury.

The pathway which results in a loss of intestinal barrier function and transepithelial transfer of macromolecules after cutaneous thermal injury is unknown. To determine the enhanced absorption pathway, transepithelial transport of horseradish peroxidase (HRP) was examined ultrastructurally after a thermal injury. Within 6 h after the injury, increased HRP uptake was seen in the portal and systemic blood with the maximal increase in uptake measured at 18 h postinjury; permeability returned to normal by 72 h postinjury. Morphologically, the increased uptake was found to be transcellular through ultrastructurally normal intestinal absorptive cells. Occasional focal regions of enhanced HRP uptake were found and this enhanced uptake was attributed to focal intestinal epithelial disruptions. This increase in intestinal permeability represents a transient loss of intestinal barrier function and potentially allows absorption of macromolecules such as endotoxin from the intestinal lumen into the portal circulation early after thermal injury.

Animals↗
PubMed1992

Effect of chronic interleukin-2 treatment on RES phagocytic activity in the rat.

The effect of chronic interleukin-2 (IL-2) injection upon reticuloendothelial system (RES) function in the rat has been determined. Seven-day treatments with two doses of human recombinant IL-2 resulted in a dramatic reduction in the phagocytic uptake of the liver and spleen, while increasing the weight of both organs. There were dramatic histological changes in the intestine, liver and spleen as well. These results suggest that the chronic use of IL-2 can result in hepatic dysfunction, which is associated with altered RES phagocytic function.

Animals↗
PubMed1992

Effect of heta-starch colloidal solutions on reticuloendothelial phagocytic system (RES) function in burned and infected rats.

The biodistribution of the plasma expander colloidal solution, heta-starch (HES), has been examined in rats, subjected to thermal injury or sepsis. The ability of these solutions to alter RES phagocytic function of [99mTc]-sulphur colloid ([99mTc]SC) uptake in vivo has been examined. The biodistribution of radiolabelled HES has been determined in normal rats. The HES colloidal solution has no deleterious effect upon RES function in vivo in the thermally injured animals or the septic animals as compared to sham controls. In addition, the HES colloidal solution seemed to be distributed primarily within the liver, spleen and kidney, with a small amount residing in the lung. Thermal injury did not increase the uptake of this material by the lung. These results suggest that the use of HES in thermally injured and septic individuals has no deleterious effects on RES function, nor does it accumulate in the lungs, and hence, should be advocated for use in these situations.

Animals↗
PubMed1992

Reduction in biliary IgA after burn injury. Role of diminished delivery via the thoracic duct and of enhanced loss from the systemic circulation.

The concentration of biliary IgA is greatly reduced after scald burn injury in the rat, thereby contributing to a deficiency in upper intestinal immune defense. This reduction in biliary IgA might have several explanations, including failure of the transhepatic transport of polymeric IgA (pIgA) from the circulation, decreased delivery of pIgA to the hepatocyte, or decreased local synthesis of IgA in the liver. The authors examined whether burn injury reduces circulating pIgA available for delivery to the hepatocyte. In initial studies, they demonstrated that burn injury induces a decrease in circulating pIgA in bile-duct-ligated rats. They then sought to determine whether this decrease in pIgA was due to increased loss from the circulation or to a decreased supply of pIgA to the circulation through the thoracic duct. After injection of purified 125I-pIgA into bile duct-ligated rats, radioactivity was removed more rapidly from the circulation of burn-injured compared with control rats. The radioactivity localized in the skin and muscle at the site of burn injury. In another group of rats with patent bile ducts, the thoracic duct was cannulated and lymph collected for 12 hours. The total amount of IgA protein in lymph was found to be reduced in burn-injured compared with control animals. Thus, burn injury is accompanied by reduced circulating pIgA, which may be attributed to its enhanced loss from the circulation and to decreased delivery of pIgA from the intestinal mucosa to the systemic circulation via the thoracic duct.

Animals↗
PubMed1992

Percutaneous drainage of a thigh haematoma: case report of an unusual radiographic appearance.

We present a case of fat necrosis in the thigh of a ten year old girl, resulting in unusual multiple, ovoid filling defects seen in the residual cavity following drainage of a subcutaneous haematoma. No similar cases have been found on review of the literature. The appearance is described to aid diagnosis at the time of initial cavity drainage, avoiding the need for further investigation.

Child↗
PubMed1992

Effect of thermal injury on transfer of IR22 IgA myeloma protein into bile in the rat.

We previously observed a 75-90% decrease in concentration of biliary IgA after thermal injury to rat skin. Decrease in biliary IgA might result from an alteration in supply of polymeric IgA delivered to the hepatocyte or from an alteration in hepatocyte transfer of polymeric IgA into bile. In the present study, we examined the transfer of intravenously administered 125I-IgA into bile. Purified IR22 rat IgA myeloma protein consisting of both monomeric and polymeric IgA was labelled with 125I. Sprague-Dawley rats (140-180 g) received a 20-30% body surface area scald-burn or sham treatment. The bile duct was cannulated 18-24 h later and 125I-IgA preparations were injected into the tail vein. Bile was collected under light ether anesthesia for 3 h. In rats injected with 125I-IR22 IgA myeloma protein there were no significant differences in total, TCA-precipitable, or immunoprecipitable radioactivity in bile from burn-injured or sham-treated animals. On Bio-Gel A-1.5 m gel permeation, the radioactivity in bile from sham-treated animals eluted in the region of polymeric IgA as expected; the radioactivity in the bile from burn-injured animals eluted equally in the same regions as polymeric IgA and monomeric IgA. In sham-treated rats injected with isolated polymeric IgA only, bile contained primarily polymeric IgA. In burn-injured rats injected with polymeric IgA only, bile contained a mixture of polymeric IgA and monomeric IgA. These findings suggest that hepatocyte processing of polymeric IgA is altered after thermal injury, resulting in the transformation of some polymeric IgA into its monomeric form.

Animals↗
PubMed1991

Platelet-activating factor induces intestinal necrosis, but not septic shock, in germ-free and specific-pathogen-free rodents.

Platelet-activating factor (PAF) was injected into conventional mice, endotoxin-resistant mice (C3H/HEJ), conventional rats, germ-free rats and specific-pathogen-free (SPF) mice. The PAF resulted in significant necrosis and damage to the small intestines of all the animals tested. In general, the frequency and severity of the lesions were similar in all groups. All the conventional rats and mice, as well as the endotoxin-resistant HEJ mice, were dead 18 h after the injection of the PAF, while all the germ-free rats and the SPF mice survived. These data demonstrate that development of massive intestinal lesions, in the absence of aerobic bacteria, is not sufficient to cause the death of the host from septic shock and endotoxaemia.

Animals↗
PubMed1991

Effect of haemolysis on reticuloendothelial system (RES) phagocytic activity in rats.

The role of haemolysis of blood in the alterations in the uptake of [99mTc]SC ([99mTc]-sulphur colloid) in vivo in the rat has been examined. When the haemolysed blood (produced by first freezing the blood in liquid nitrogen) was infused into synergenic Lewis rats via the tail vein, there was a significant reduction in the uptake of the [99mTc]SC by the spleen, but lung, liver and kidney uptake remained constant. These results suggest that haemolysis of the blood may play a role in the alterations in RES phagocytic activity observed in the spleen following thermal injury.

Animals↗
PubMed1991

Proteoglycan synthesis in human skin and burn scar explant cultures.

The synthesis of proteoglycans (PG) by normal human skin, and normal and hypertrophic scars were compared using tissue explants in culture. Newly synthesized PG were labelled with [35S]Na2SO4. Significant differences were found in the proportion of [35S]-radio-labelled incorporation of PG in the tissue and accumulation of [35S]PG in culture medium in the different tissues. The rate of PG biosynthesis in all three tissue types occurred in two phases. There was an initial phase of PG synthesis occurring at 0-3 h and a later phase that occurred at 3-18 h [35S]-labelled PG were isolated and characterized by Sepharose CL-6B chromatography and cellulose acetate electrophoresis. The results showed that the hypertrophic scar tissue and its culture medium contained higher proportions of dermatan sulphate (DS), chondroitin sulphate (CS) and DS' PG than the normal skin fractions. These results suggest that abnormal scarring is related to a change in the level of PG synthesis during the burn injury repair process.

Burns↗
PubMed1991

Effect of platelet activating factor on reticuloendothelial system function.

The effect of platelet activating factor (PAF) injections on the uptake of 99mTc-SC (99mTc-SC (99mTc-sulphur colloid) was determined in vivo. PAF (2 micrograms) injected intravenously into unanaesthetized, unrestrained rats was associated with the development of lesions in the small intestine and alteration of 99mTc-SC uptake in vivo. 99mTc-SC uptake into the lung was increased while spleen uptake was decreased. Pretreatment of the animals with a PAF antagonist, SRI-64-441, prevented the intestinal lesions and alterations of 99mTc-SC uptake. Macrophages, isolated from lung lavage of the PAF-treated rats, demonstrated a decreased generation of hydrogen peroxide in vitro. The present results suggest that, in addition to its other effects on the immune system, PAF can also alter the in vivo phagocytic activity of the reticuloendothelial system in the rat.

Animals↗
PubMed1991

The rat lung organotypic culture: an in vitro model for studying surfactant metabolism abnormalities.

The amount of surfactant present in the intra-alveolar space is mainly regulated by the synthesis and recycling of surfactant by type II pneumocytes. Biochemical analyses have shown that the surfactant level is frequently diminished and that protein-rich exudate can further interfere with surfactant function in the lungs of adult respiratory distress syndrome (ARDS) patients. The microenvironmental changes that occur in the alveoli of burned patients, who are prone to developing ARDS, are unclear. Therefore, using an in vitro rat lung organotypic culture, we showed that the sera of rats with a 3-day old, third-degree thermal injury (25-30% total body surface area) inhibited surfactant synthesis in organotypically cultured rat lung cells. Surfactant precursor, 3H-choline, incorporation into the surfactant was 58% of control. Using liposomes made of dipalmitoyl phosphatidylcholine and phosphatidylglycerol (8:1, v/v) or surfactant we showed that surfactant endocytosis by purified type II alveolar cells is an active, temperature-dependent process, and correlates with the quantity of surfactant present in the milieu. We also found that plasma protein-rich fluid interfered with surfactant endocytosis by the purified type II pneumocytes. These two processes of inhibition of surfactant synthesis and its reutilization by these cells may contribute to the pathogenesis of ARDS.

Animals↗
PubMed1990

Injury-induced inhibition of small intestinal protein and nucleic acid synthesis.

Small intestinal mucosal weight and nutrient absorption are significantly diminished early after cutaneous thermal injuries. Because these intestinal properties are highly dependent on rates of nucleic acid and protein synthesis, in vivo incorporation of thymidine, uridine, and leucine into small intestinal deoxyribonucleic acid, ribonucleic acid, and proteins were measured. Deoxyribonucleic acid synthesis was markedly decreased with the lowest thymidine incorporation in the jejunum (p less than 0.01); these findings were confirmed by autoradiographic identification of radiolabeled nuclei in the intestinal crypts. Protein synthesis was decreased by 6 h postinjury (p less than 0.01) but had returned to normal by 48 h. Consistent with a decreased rate of protein synthesis, ribonucleic acid synthesis was also decreased 18 h postinjury (p less than 0.01). These decreased deoxyribonucleic acid, ribonucleic acid, and protein synthesis rates are not likely a result of ischemia because in other studies of this injury model, intestinal blood flow was not significantly changed by the burn injury. Potentially, factors initiating the acute inflammatory reaction may directly inhibit nucleic acid and protein synthesis and lead to alterations in nutrient absorption and intestinal barrier function after injury.

Animals↗
PubMed1990

Prevention of necrotizing enterocolitis in the rat with prenatal cortisone.

Cortisone acetate is known to accelerate maturation of the immature intestine. The effect of prenatal administration of cortisone acetate on the morbidity and mortality of necrotizing enterocolitis was examined in a rat pup model. Pregnant rats were administered cortisone acetate, 20 mg/100 g of body weight, or normal saline by daily IP injection from day 18-21 of gestation. Rat pups were taken from the mothers before suckling was initiated, fed a simulated rat milk formula, and subjected to daily ischemic insults to produce an animal model of necrotizing enterocolitis. Both morbidity and the mortality rates were significantly improved with prenatal cortisone treatment. Maturation of the intestinal mucosal barrier was accelerated with the cortisone treatment as measured by decreased serum concentrations of a fed antigen, ovalbumin. Aerobic bacterial colonization of the small intestine and translocation of bacteria to the liver were decreased in the pups pretreated with steroids. These changes observed in a rat model of necrotizing enterocolitis may explain the decreased incidence of necrotizing enterocolitis in human infants born to mothers who received corticosteroids late in gestation.

Animals↗
PubMed1990

Role of neutrophils in the intestinal alterations associated with thermal injury.

We have examined the role of neutrophils in the alterations observed in the intestines of rats subjected to 40 per cent surface area scald injury. Histologically, there was no evidence of neutrophilia in the intestinal tissue, and myeloperoxidase activity in mucosal scrapings was not elevated. The distribution of labelled human neutrophils injected into the burned rats showed no enhancement of uptake in the intestines, although there was increased uptake by the lung. The present data suggest that neutrophil migration may not play a role in the alterations in small intestinal function and morphology seen in burn trauma in the rat, but may be a factor in lung damage associated with thermal injury.

Acute Disease↗