Endotoxin may cause abnormal deposition of platelet-endotoxin aggregates, and this event could have damaging effects. We compared the aggregation characteristics of platelets from rabbits made tolerant to the lethal effects of endotoxin with those of platelets from normal rabbits. Platelets from tolerant rabbits aggregated more rapidly (greater than 90 s faster) in the presence of endotoxin than did platelets from nontolerant animals. Furthermore, platelets from tolerant animals aggregated reversibly. These characteristics of platelets from tolerant animals are due to humoral factors in the plasma, because 1:1 dilution of normal platelet-rich plasma with plasma from tolerant rabbits caused the normal platelets to behave like those from tolerant animals. Survival after challenge with lethal quantities of endotoxin was enhanced in tolerant rabbits; this may be due to promotion of more efficient removal of endotoxin-platelet complexes from the blood by the reticuloendothelial system.

Animals↗

PubMed1978

Disruption of the permeability barrier (zonula occludens) between intestinal epithelial cells by lethal doses of endotoxin.

A freeze-fracture technique was used to examine the most apical intercellular junctional complex between intestinal epithelial cells (the tight or occluding junction) in mice after challenge with endotoxin. Some of these junctions were disrupted after challenge and may be a site for leakage of microbial agents from the lumen.

Animals↗

PubMed1978

Biologic properties of bacterial lipopolysaccharides treated with chromium chloride.

Addition of small amounts of chromium chloride to a saline suspension of Salmonella typhosa lipopolysaccharide (LPD; Difco) caused a marked reduction in several of the biologic activities of this substance including toxicity, B-cell mitogenicity, plasma colony-stimulating activity (CSA), radioprotective effect, and induction of the dermal Shwartzman reaction. Nevertheless, LPS treated with chromium chloride was found to be at least as effective as untreated LPS in enhancing resistance of B6CBF1 mice to the lethal effects of Klebsiella pneumoniae infection.

Adjuvants, Immunologic↗

PubMed1978

Possible association of granulocyte mobilization to the peritoneal cavity with ZnCl2-induced protection against endotoxin.

We have attempted to determine which components of the inflammatory response are responsible for ZnCl2-induced retention of endotoxin in the peritoneal cavity and enhancement of survival following challange with the toxin. ZnCl2 injected intraperitoneally into mice caused accumulation of granulocytes in the peritoneal cavity, but these cells were apparently not responsible for the trapping process. This contention in supported by our observation that reduction of hepatosplenic uptake of 51CR-labeled endotonxin was similar in unirradiated mice and in mice made by irradiation (1000 rad 60 Co) 1 rad = 10 (-2) J/kg). Hepatosplenic uptake was also depressed when untreated mice were injected with endotoxin suspended in cell-free plasma. Furthermore, zinc did not protect irradiated mice challanged with endotoxin, although it enhanced survival in urirradiated animals. Lack of protection in irradiated mice may be due to a deficiency in the cellular response in the peritoneal cavity.

Animals↗

PubMed1978

The contribution of intestinal endotoxin to mortality in hosts with compromised resistance: a review.

Sepsis, particularly with endotoxin-containing Gram-negative bacilli, is a serious complication in hosts whose defenses are compromised. This review examines work from our laboratory and others concerning infectious processes which may be critical to the survival of compromised individuals. Several avenues for control of sepsis are proposed. Gram-negative bacteria and their endotoxins can escape from the intestines of compromised animals to contaminate normally sterile host tissues. Endotoxins are especially toxic to compromised hosts because essential components of their inflammatory responses are missing (i.e., leukocytes and platelets in irradiated animals). Therefore, regulation of host responses to endotoxin is no longer possible. It is recommended that sepsis be controlled in compromised individuals through elimination of endogenous microbial agents. Should infection occur in these individuals, they should be transfused with blood cells necessary for clearance of bacteria and endotoxin and restoration of homeostasis.

Animals↗

PubMed1978

Antibiotic decontamination of the dog and its consequences.

An isolation-decontamination regimen was developed which effectively reduced the numbers of resident flora of the dog. Bacterial counts in four dogs before treatment were 3.8 X 10(9) per gram of feces; no organisms were detectable in these same dogs after treatment, however, the intestinal flora had returned to slightly above normal levels 1 week after treatment. Decontamination was accomplished in a laminar air flow system designed to minimize the area that had to be under controlled conditions. By determining the antibiotic sensitivities of 67 isolated organisms representing eight species or groups of bacteria recovered from the four dogs, a standardized antibiotic regimen was developed consisting of bacitracin and neomycin administered as a dry powder in the food. The decontamination treatment apparently did not affect host metabolism because no alterations in serum levels of urea nitrogen, glucose, phosphate, total protein, chloride, sodium, potassium, serum glutamic oxalacetic transaminase, or serum glutamic pyruvic transaminase were found in the antibiotic-treated dogs. The decontamination process did, however, reduce normal granulopoietic stimulation.

Animals↗

PubMed1978

Endotoxin-induced alterations in canine granulopoiesis: colony-stimulating factor, colony-forming cells in culture, and growth of cells in diffusion chambers.

Salmonella typhosa endotoxin injected into dogs produced elevated plasma CSF levels, transient leukopenia followed by leukocytosis, and stimulation of marrow granulopoiesis and mobilization of granulocyte-macrophage progenitors cells into the the peripheral circulation. The number of marrow CFU-c decreased to 65% of the control number within 6 h, returned to control levels by 24 h, and increased to 370% of the control number by 48h after endotoxin. The granulopoietic response was supported by a concomitant increase in the M:E ratio, an increased fraction of marrow-derived CFU-c susceptible to 3H-TdR suicide, and increased granulo-monocytopoietic activity of marrow- and peripheral blood-derived cells grown in diffusion chamber cultures. These results are consistent with the concept that endotoxin-induced CSF is a physiologic regulator of canine granulopoiesis, and that canine marrow responds to endotoxin with a significant increase in the concentration of marrow-derived granulocytic progenitors and with mobilization of granulocyte-macrophage progenitors into the peripheral circulation.

Animals↗

PubMed1978

Canine granulopoiesis: alterations induced by suppression of gram-negative flora.

We investigated alterations in canine granulopoiesis following suppression of bacterial flora by antibiotic treatment. Beagles were decontaminated in sterile isolation with laminar air flow, by an antifungal and antibiotic regimen. Skin and fecal specimen cultures were usually negative after 4 days. The reduction of gram-negative bacteria resulted in a significant decrease in plasma colony-stimulating factor (CSF) levels, marrow CFU-c concentration, and the cytopoietic activity of marrow-derived diffusion chamber (DC) progenitor cells. The period of conventionalization was characterized by a significant although delayed increase in plasma CSF as well as marked increases in marrow CFU-c concentration and cytopoietic activity of marrow DC progenitors. There was also mobilization of marrow DC progenitors into the circulation. All parameters returned to control values within 7 days of conventionalization. These data supported the hypothesis that the gram-negative bacteria of the gut play a significant role in the regulation of normal canine granulopoiesis.

Animals↗

PubMed1978

Marrow culture in diffusion chambers in rabbits. I. Effect of mature granulocytes on cell production.

Factors influencing granulopoiesis have been evaluated using diffusion chambers implanted in the peritoneal cavity of rabbits. An increase in granulopoiesis in chambers implanted in hosts made neutropenic by nitrogen mustard occurs in mice made neutropenic by x-ray or drug. The intraperitoneal injection of leukocytes inhibited the growth of cells in chambers implanted in rabbits. Removal of mature granulocytes from marrow prior to chamber inoculation produced a marked in-increase in cell growth, especially of granulocytes. Mature granulocytes clearly inhibited cell replication and this inhibition involved both myeloid and erythroid elements, although the data suggest a greater effect on myelopoiesis. In contrast to the mouse, erythropoiesis in chambers in rabbits remained prominent for over 1 wk.

Animals↗

PubMed1978

Marrow culture in diffusion chambers in rabbits. II. Effect of competing demands for red cell and white cell production on cell growth.

Studies were done of cell production by marrow in diffusion chambers implanted in the peritoneal cavity of rabbits subjected to various stimuli to hematopoiesis. In chambers in neutropenic hosts and in hosts injected with endotoxin, animals presumed to have an increased stimulus to granulopoiesis, there was increased production of granulocytes but there was also increased production of red cells. Although red cell production was decreased in chambers in polycythemic hosts, granulocyte production was not different from that in controls. Stimulation of erythropoiesis by erythropoietin injections or by exposure to hypoxia increased red cell production by marrow in the implanted diffusion chambers without diminishing granulopoiesis. Only in chambers in hosts made anemic by bleeding was there an increase in red cell production accompanied by a decrease in granulocyte production. In these anemic hosts induction of neutropenia led to an increase in granulopoiesis without any depression of erythropoiesis.

Anemia↗

PubMed1978

Effect of cycloheximide on the bone marrow toxicity of nitrogen mustard.

Cycloheximide (CHM), a potent inhibitor of protein synthesis, has been reported to protect rat intestinal crypt cells from mitotic inhibition by nitrogen mustard (HN2). For investigation of the effect of CHM on the bone marrow toxicity of HN2, CHM (1.0 mg/kg) and HN2 in doses up to 2.5 mg/kg were given i.p. to rats. Twenty-eight % (13 of 46) of rats given HN2 alone died within 5 days. Only 4% (2 of 45) of rats pretreated with CHM died within 5 days after the administration of HN2. Rats pretreated with CHM had significantly less leukopenia and granulocytopenia than did rats given HN2 alone, and their bone marrow cellularity, assessed by histological sections and total femoral marrow cell counts, was greater than that of animals given HN2 alone. Bone marrow DNA synthesis, as measured by in vitro [3H]thymidine incorporation, was decreased 2 hr after HN2 injection, appeared to recover at 4 hr, but was further decreased at 24 and 48 hr. CHM given up to 20 min before HN2 reversed the effect of HN2 on DNA synthesis at 2 and 4 hr. A variable protective effect of CHM was observed at 24 and 48 hr. These studies indicate that CHM increases the survival of HN2-treated rats and partially protects rat bone marrow cells from HN2 cytotoxicity.

Animals↗

PubMed1977

Protection against endotoxin-induced mortality in mice treated with transition metal salts.

Administration of manganese or chromium chloride 1 h before challenge with a single bolus of Salmonella typhosa endotoxin completely obviated death in endotoxin-challenged mice.

Animals↗

PubMed1977

Role of zinc in the abatement of hepatocellular damage and mortality incidence in endotoxemic rats.

Intraperitoneal administration of zinc (ZnIP) as zinc chloride prior to or simultaneously with a lethal quantity of intraperitoneally administered Salmonella typhimurium endotoxin significantly protected rats against toxin-induced mortality and hepatocellular damage. Pretreatment with amounts of zinc chloride ranging from 0.4 to 2.0 mg/100 g of body weight resulted in 80 to 100% survival compared with 10% survival in untreated control rats at 24 h after endotoxin treatment. Zinc chloride treatment in excess of 2.0 mg/100 g of body weight appeared to be toxic and provided diminished protection. In contrast with the protection obtained with ZnIP, intravenously administered zinc did not provide protection. The effectiveness of ZnIP to enhance survival if it was given after endotoxin was greatly diminished as a function of time after endotoxin. The extent of hepatocellular damage was assessed at various times after endotoxin administration in ZnIP-treated and untreated rats by measurement of plasma ornithine carbamoyltransferase activity and histological examination of liver sections. Endotoxin absorption from the peritoneal cavity and hepatic uptake were studied by using 51Cr-labeled endotoxin. ZnIP pretreatment significantly reduced 51Cr-labeled endotoxin content of blood and liver when compared to untreated controls, and effectively prevented endotoxin-induced elevations in plasma ornithine carbamoyltransferase activity and hepatic tissue necrosis. These data indicate that protection afforded by ZnIP treatment results as a consequence of the ability of zinc to diminish absorption of the toxin from the peritoneal cavity and subsequent hepatic uptake.

Absorption↗

PubMed1977

Evidence of bacteremia and endotoxemia in mice undergoing hyperbaric stress.

Swiss albino mice were exposed to normoxic (PO2 approximately 0.2 ATA) helium at 1, 20 or 35 ATA for 2 or 48 h and examined for the presence of bacteria and endotoxin in selected tissues. Among mice exposed to 35 ATA for 48 h and tested immediately after decompression for bacteria in liver and peritoneal cavities, 6 of 30 (20%) contained gram-negative rods and 27 of 30 (90%) contained gram-positive cocci. Incidence of infection was considerably less in mice exposed to 35 ATA for 2 h or exposed to 1 ATA. Evidence of presence of gram-negative rods and /or escape of free endotoxin from the intestine was provided by demonstration that limulus lysate is coagulated (presumptive evidence of endotoxin) by liver homogenates in 70% of the mice exposed to 35 ATA for 48 h, 68% of those exposed to 20 ATA and 14% of those exposed to 1 ATA. Mice subjected to the hyperbaric stress of 35 ATA for 48 h were shown to be increasingly susceptible to injection with purified lipopolysaccharide. The LD50 was 0.24 mg for hyperbaric exposed mice and 0.39 mg for the control groups. These data suggest that hyperbaric stress, but not necessarily decompression, results in a short-term presence in mouse tissues of microbial agents originating from the gut. This invasion temporarily renders that host more susceptible to additional endotoxic challenge.

Animals↗