Clinical assessment of the activity of tumor necrosis factor (TNF) against human cancer has been limited by a dose-dependent cardiovascular toxicity, most frequently hypotension. TNF is also thought to mediate the vascular collapse resulting from bacterial endotoxin. The present studies address the mechanism by which TNF causes hypotension and provide evidence for elevated production of nitric oxide, a potent vasodilator initially characterized as endotheliumderived relaxing factor. Nitric oxide is synthesized by several cell types, including endothelial cells and macrophages, from the guanidino nitrogen of L-arginine; the enzymatic pathway is competitively inhibited by -me yl-L-arginine. We found that hypotension induced in pentobarbital-anesthetized dogs by TNF (10 ,ug/kg, i.v., resulting in a fall in mean systemic arterial pressure from 124.7 ± 7 to 62.0 ± 22.9 mmHg; 1 mmHg = 133 Pa) was completely reversed within 2 min following administration ofNG-methyl-L-arginine (4.4 mg/kg, i.v.). In contrast, NG-methyl-L-arginine failed to reverse the hypotensive response to an equivalent depressor dose of nitroglycerin, a compound that acts by forming nitric oxide by a nonenzymatic, arginine-independent mechanism. The effect of NG-methyl-L-arginine on TNF-induced hypotension was antagonized, and the hypotension restored, by administration of excess L-arginine (100 mg/kg, i.v.). Our rmdings suggest that excessive nitric oxide production mediates the hypotensive effect of TNF.Tumor necrosis factor (TNF) is a cytotoxic protein produced by macrophages upon activation by bacterial endotoxin (1, 2). In addition to a spectrum of cytotoxic and immunologic actions, TNF causes marked hypotension in mammals (1, 3). The observations that bacterial endotoxin elicits TNF production (4, 5) and that pretreatment of animals with anti-TNF antibodies abolishes the hypotensive action of endotoxin (6) suggest that TNF is the key mediator of endotoxic shock in vivo. Although TNF is known to promote hemorrhagic necrosis of some animal tumors (7), its clinical promise as an antineoplastic agent is limited by severe dose-dependent side effects, predominantly hypotension (8, 9). Despite the clinical importance of TNF-induced hypotension, its mechanism is unknown.The present study addresses the possibility that increased nitric oxide production accounts for TNF-induced hypotension. Earlier studies established that endothelium-derived nitric oxide is a labile modulator of vascular tone (10, 11). Originally termed endothelium-derived relaxing factor (EDRF, ref. 12), nitric oxide is responsible for the vascular smooth muscle relaxation elicited by acetylcholine, bradykinin, and many other endogenous vasorelaxants. L-Arginine is the biosynthetic precursor of endothelium-derived nitric oxide (13)(14)(15)(16), and NG-methyl-L-arginine (L-MeArg) is a competitive inhibitor of this pathway (14, 15). The finding that administration of L-MeArg causes a moderate increase in blood pressure by an arginine-reversible mechanism in the anesthetized guine...

No abstract

SummaryBackgroundBullous pemphigoid is a blistering skin disorder with increased mortality. We tested whether a strategy of starting treatment with doxycycline gives acceptable short-term blister control while conferring long-term safety advantages over starting treatment with oral corticosteroids.MethodsWe did a pragmatic, multicentre, parallel-group randomised controlled trial of adults with bullous pemphigoid (three or more blisters at two or more sites and linear basement membrane IgG or C3). Participants were randomly assigned to doxycycline (200 mg per day) or prednisolone (0·5 mg/kg per day) using random permuted blocks of randomly varying size, and stratified by baseline severity (3–9, 10–30, and >30 blisters for mild, moderate, and severe disease, respectively). Localised adjuvant potent topical corticosteroids (<30 g per week) were permitted during weeks 1–3. The non-inferiority primary effectiveness outcome was the proportion of participants with three or fewer blisters at 6 weeks. We assumed that doxycycline would be 25% less effective than corticosteroids with a 37% acceptable margin of non-inferiority. The primary safety outcome was the proportion with severe, life-threatening, or fatal (grade 3–5) treatment-related adverse events by 52 weeks. Analysis (modified intention to treat [mITT] for the superiority safety analysis and mITT and per protocol for non-inferiority effectiveness analysis) used a regression model adjusting for baseline disease severity, age, and Karnofsky score, with missing data imputed. The trial is registered at ISRCTN, number ISRCTN13704604.FindingsBetween March 1, 2009, and Oct 31, 2013, 132 patients were randomly assigned to doxycycline and 121 to prednisolone from 54 UK and seven German dermatology centres. Mean age was 77·7 years (SD 9·7) and 173 (68%) of 253 patients had moderate-to-severe baseline disease. For those starting doxycycline, 83 (74%) of 112 patients had three or fewer blisters at 6 weeks compared with 92 (91%) of 101 patients on prednisolone, an adjusted difference of 18·6% (90% CI 11·1–26·1) favouring prednisolone (upper limit of 90% CI, 26·1%, within the predefined 37% margin). Related severe, life-threatening, and fatal events at 52 weeks were 18% (22 of 121) for those starting doxycycline and 36% (41 of 113) for prednisolone (mITT), an adjusted difference of 19·0% (95% CI 7·9–30·1), p=0·001.InterpretationStarting patients on doxycycline is non-inferior to standard treatment with oral prednisolone for short-term blister control in bullous pemphigoid and significantly safer in the long-term.FundingNIHR Health Technology Assessment Programme.

In patients who are haemodynamically stable, the RRT modality does not appear to influence important patient outcomes, and therefore the preference for CRRT over IRRT in such patients does not appear justified in the light of available evidence. CRRT was shown to achieve better haemodynamic parameters such as MAP. Future research should focus on factors such as the dose of dialysis and evaluation of newer promising hybrid technologies such as SLED. Triallists should follow the recommendations regarding clinical endpoints assessment in RCTs in ARF made by the Working Group of the Acute Dialysis Quality Initiative Working Group.