A monoclonal antibody to recombinant murine tumor necrosis factor-alpha (TNF alpha), TN3-19.12, was used to explore pathogenetic mechanisms and therapeutic strategies in gram-negative shock. In mice receiving an LD90 dose of Escherichia coli O111, TN3-19.12 prevented death if given 1.5 h before or 30 min after challenge. Less protection was conferred if the antibody was given 2.5 h after challenge. In control mice receiving an irrelevant antibody, L2-3D9, TNF alpha levels rose (less than or equal to 185.1 +/- 26.1 ng/ml) by 90 min and had returned to baseline by 5 h. Mice receiving TN3-19.12 did not have this response. TN3-19.12 was of limited benefit in mice receiving Pseudomonas aeruginosa but had no protective effect in cyclophosphamide-treated mice receiving Klebsiella pneumoniae. In L2-3D9-treated mice, TNF alpha levels were elevated to 61.8 +/- 27.9 and 49.7 +/- 5.1 ng/ml by 90 min in the two models, respectively. TNF alpha levels in TN3-19.12-treated mice in these two models were very low (3.9-5.5 ng/ml). TNF alpha is a mediator in gram-negative shock; antibody to TNF alpha can be of value in prophylaxis and treatment, but its clinical use remains to be established.
To study the role of interferon-gamma (IFN-gamma) in gram-negative shock, mortality was compared in mice receiving either a monoclonal antibody to IFN-gamma (H22) or an irrelevant monoclonal antibody (L2-3D9) before or after an LD90 dose of Escherichia coli O111:B4. H22 given either 1 h before or 0.5 h after bacterial challenge protected mice from death (mortality at 48 h, 28% vs. 83%, P less than .001). Serum tumor necrosis factor-alpha (TNF alpha) levels and bacterial counts in blood and organs (liver, spleen, heart, and brain) were similar in H22-treated animals and controls. The peak serum TNF alpha levels were 95.7 +/- 16.4 ng/mL and 80.7 +/- 14.9 ng/mL in the H22 and control groups, respectively. These results indicate that IFN-gamma plays a significant role in the pathogenesis of gram-negative sepsis.
1.A method was developed for extracting enzymes from micro-organisms closely associated with ammoniatreated straw (NH,-S) that had been incubated in nylon bags in the rumen. Incubation of washed straw with 125 ml carbon tetrachloride/l and 20 pg lysozyme/ml for 3 h at 37 gave carboxymethylcellulase (EC 3 . 2 . 1 . 4 ; CMCase) and NAD-linked glutamate dehydrogenase (EC 1 . 4 . 1 .2; GDH) activities greater than those extracted by sonication.2. GDH associated with NH,-S increased with incubation time and was highest in sheep receiving a high-barley diet. Particle-bound CMCase activity reached a peak between 16 and 24 h and declined thereafter.3. Particle-bound GDH activity showed no correlation with dry matter (DM) degradation in the rumens of sheep fed on a range of diets. In contrast, CMCase activity after 24 h was highly correlated with DM degradability of the same samples at 24 h (r 0.98) and 48 h (r 0.94).4. It was concluded that GDH and CMCase can be used as indices of the total population of colonizing rumen micro-organisms and of the fibre-degrading population respectively, and that these enzymes can therefore be used to assess rapidly and with great sensitivity variations in the rumen environment that affect the rate of fibre breakdown.
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