Monoclonal Antibody Therapy for Gram-Negative Sepsis: Principles,Applications, and Controversies

Gram-negative sepsis is a common event in hospitalized patients and is a leading cause of death in the United States. Endotoxin (lipopolysaccharide, LPS), a component of the cell wall of gram-negative microorganisms, is responsible for the cascade of events leading to the sepsis syndrome consisting of fever, tachycardia, tachypnea, and evidence of organ hypoperfusion. The lipid A region of endotoxin produces most of these biologic and toxic effects. Monoclonal IgM antibodies directed against the lipid A portion of endotoxin (anti-LPS MoAb) have been developed for the treatment of gram-negative sepsis. Results of two large-scale clinical trials suggest that these antibodies offer clinically and statistically significant reductions in mortality by a factor of about one-third. However, in both trials, this apparent beneficial effect was limited to particular subsets of patients, and no overall benefit was seen. These considerations, in addition to the likely high cost of the agents, pose questions about their ultimate use in the treatment of patients with gram-negative sepsis. Nevertheless, the logic of the approach, the demonstration of efficacy in disease models, and the advances in modern techniques of molecular biology all suggest that these or other closely related products will play a significant role in the treatment of this disorder.     

Investigation of adrenergic and prostaglandin influences in the endotoxin alteration of hepatic heme oxygenase, microsomal mixed-function oxidase, and glucocorticoid-induced tryptophan oxygenase activities

The possible role for adrenergic influences or prostaglandins in the effects of endotoxin to inhibit the glucocorticoid induction of hepatic tryptophan oxygenase (TO) activity, to decrease the hepatic microsomal cytochrome P--450-dependent drug-metabolizing activity, and to induce heme oxygenase activity was examined. Administration of the alpha-adrenergic locking agents phenoxybenzamine or phentolamine attenuated the inhibitory effect of the bacterial lipopolysaccharide on the induction of TO activity by dexamethasone. Injection of a beta-adrenergic blocker, propranolol, or of indomethacin, an inhibitor of prostaglandin biosynthesis, accentuated the effect of endotoxin to inhibit TO induction. Neither phenoxybenzamine, propranolol, nor indomethacin altered the effect of endotoxin to decrease aniline hydroxylase activity, ethylmorphine N-demethylase activity, or the levels of cytochrome P--450. Also, dexamethasone administration did not significantly protect against the effects of endotoxin on the hepatic microsomal drug metabolizing enzyme system, and none of the pharmacological agents diminished the effects of endotoxin to induce hepatic heme oxygenase activity. Endotoxin administration was also shown to diminish, but not prevent, the induction of cytochrome P--450 and ethylmorphine N-demethylase activity produced by phenobarbital. The results indicate that alpha-adrenergic mechanisms are involved in the endotoxic inhibition of the glucocorticoid induction of TO activity and suggest that neither adrenergic influences nor prostaglandins play a significant role in the effect of endotoxin to decrease hepatic mixed-function oxidase activity.     

微生态调节剂及其在肝病治疗中的应用

微生态调节剂的开发与研究受到人们的普遍重视。肝炎后肝硬化患者肠道中的有益菌(双岐杆菌等)减少或消失,大肠杆菌等增加并转为优势菌,导致血内毒素升高。肠道菌群紊乱与肝功能损害程度密切相关。因此,正确使用微生态调节剂可以维护肝硬化患者的肠道微生态平衡,减少内毒素的产生与吸收,对稳定病情起着积极的作用     

Further observations on mesenteric vasoconstriction, survival and the clotting defect after endotoxin administration

1. The initial response after endotoxin administration (3 mg/kg) in cats involved pulmonary vasoconstriction. This was not seen when endotoxin was given by slow infusion and it could be prevented after a bolus injection of endotoxin by pretreatment of the cats with aspirin (10 mg/kg). Intense mesenteric vasoconstriction occurred in all the cats.2. The mesenteric vasoconstriction was a specific response of the mesenteric blood vessels. At the time the mesenteric bed constricted, the renal bed dilated, the hepatic arterial bed remained unchanged and the smooth muscle of the intestinal wall relaxed.3. Arterial blood from cats with a fully developed mesenteric vasoconstriction after endotoxin administration was perfused through a normal intestine. No immediate vasoconstriction developed but the perfused intestine constricted slowly over 60 minutes. This suggests that mesenteric constriction was not due to circulating vasoconstrictor factors or the intestinal innervation, but involved a slow local mechanism within the intestine. It could not be prevented or reversed by a variety of pharmacological agents.4. These observations suggest that endotoxin caused a unique type of mesenteric vasoconstriction in cats by a local mechanism which took up to 60 min to develop, was sufficiently potent to reduce mesenteric flow to <30% control, and was maintained until death of the cats. Blood from these animals did not clot when placed in a glass tube.5. The mesenteric constriction and the clotting defect could be prevented by repeated administration of aminophylline and dextran solution before and after a bolus intravenous injection of endotoxin. Arterial pressure and mesenteric flow were maintained for at least 10 h in these experiments. Inadequate treatment intensified rather than reduced the intestinal mucosal damage.6. Cats were treated with aspirin, endotoxin and the optimal regimen for prevention of the mesenteric constriction and allowed to recover from the anaesthetic agent. In this series, 63% survived indefinitely compared to 25% after aspirin and endotoxin treatment and 0% after endotoxin alone.7. The possible mechanisms of action of aspirin and aminophylline-dextran solution are discussed. Our failure to obtain 100% survival is probably due to pulmonary damage which develops 10-24 h after endotoxin administration. This delayed pulmonary action of endotoxin is not prevented by aspirin treatment and it seems unlikely that aspirin will be of any value in the treatment of the pulmonary lesion in man.     

Characterization of CYP4A induction in rat liver by inflammatory stimuli: dependence on sex, strain, and inflammation-evoked hypophagia.

Acute treatment of rats with bacterial endotoxin or particulate irritants induces the expression of CYP4A mRNAs in rat liver and kidney. To determine whether all or part of these effects could be caused by hypophagia associated with the treatments, we pair-fed saline-injected rats to rats injected with endotoxin or the particulate irritant BaSO(4). The effects of endotoxin on hepatic or renal CYP4A1, CYP4A2, or CYP4A3 expression 24 h after injection were clearly distinguishable in kinetics and magnitude from those of pair feeding, indicating that the effects of endotoxin are not caused by hypophagia. Conversely, BaSO(4) treatment caused a more profound hypophagia, and pair feeding to these animals produced effects similar to those of the irritant treatment, indicating that CYP4A induction by BaSO(4) is mainly caused by reduced food intake. To gain further insight into the mechanism of induction of CYP4A by these inflammatory agents, we studied the sex dependence of their effects in Fischer 344 and Sprague-Dawley rats. No significant strain differences were observed, but the induction of hepatic CYP4A mRNAs by endotoxin or BaSO(4) was either absent in females or significantly lower than in males. This sex specificity of induction of hepatic CYP4As has been reported previously for peroxisome proliferators, and thus our results are consistent with a role for the peroxisome proliferator-activated receptor-alpha in the induction of hepatic CYP4As by inflammatory agents.     

Comparison of antibacterial potencies of oral and parenteral antibiotic preparations against Escherichia coli, Klebsiella, Citrobacter, and Proteus isolated from urinary tract infections (3: 1981) 1. Susceptibility distribution

In vitro activities of antibacterial agents against E. coli, Klebsiella, Citrobacter and Proteus which were isolated from patients with urinary tract infections at 8 hospitals in Japan, were investigated by dilution broth method using MIC 2000 (Dynatec) during July to October in 1981. The summarized results are as follows: Among oral antibacterial agents, MPC and PPA have showed potent antibacterial activities against E. coli and Klebsiella. In vitro activities of oral antibacterial agents against Proteus and Citrobacter showed not so potent. Among the first and second generation's parenteral antibacterial agents, CTM has showed potent antibacterial activities against E. coli and Klebsiella. Among the third generation's parenteral antibacterial agents, CMX, CTX and CZX have showed potent antibacterial activities against E. coli, Klebsiella, Proteus and Citrobacter.     

Lung cancer: detection, prevention, and therapeutics

Lung cancer remains the leading cause of cancer death in the U.S. adult population, and the American Cancer Society estimates that cigarette smoking is responsible for about 83% of all lung cancer cases. It is unlikely that significant reductions in the incidence and mortality associated with lung cancer will be realized without effective antismoking campaigns. Surgery, radiation therapy, and chemotherapy all play a role in the management of lung cancer. At the current time, NSCLC is generally curable only if it is diagnosed while the tumor is small and localized and can be surgically removed. Radiation therapy may also be effective in localized cases. Combination chemotherapy regimens have not consistently produced quality responses in patients with advanced tumors; however, newer regimens utilizing high doses of cisplatin, mitomycin and vinca alkaloids, or cisplatin and etoposide have produced encouraging results. In contrast to NSCLC, SCLC is responsive to combination chemotherapy regimens. Although many different agents are effective in this disease, most small-cell tumors eventually become refractory to chemotherapy and most patients do not survive longer than two years. Although progress has been made in the understanding and management of lung cancer, effective therapies that consistently produce major and durable responses are still lacking. Clinical trials must continue to evaluate therapeutic modalities for all types of lung cancer.     

Quinupristin-dalfopristin: an overview

Synercid (RP 59500), the first injectable streptogramin antibiotic, is composed of two semisynthetic pristinamycin derivatives, quinupristin and dalfopristin. Individually, each component has bacteriostatic activity against staphylococci and streptococci, but together, the agents exhibit synergy, leading to bactericidal activity. The combination drug, however, is bacteriostatic against Enterococcus faecium and has poor activity against Enterococcus faecalis. Despite a short half-life, an extended postantibiotic effect allows the agent to be dosed every 8-12 hours. Both drugs are largely hepatically metabolized and excreted in bile. Although not metabolized by cytochrome P450 3A4, quinupristin-dalfopristin can inhibit agents that are metabolized through this pathway. Dosage adjustments may be necessary in patients with hepatic dysfunction. Alterations in renal function have minimal effects on the agent's pharmacokinetics. Adverse events include arthralgia, myalgias, and infusion-related pain. Based on available data, quinupristin-dalfopristin appears to have a role in treating severely ill patients with infections due to multiresistant gram-positive pathogens.     

Foam fractionation as a method to separate endotoxin from recombinant biotechnology products.

The objective of this study was to evaluate the feasibility of foam fractionation for removal of contaminating endotoxin from biotechnology products, including plasmid DNA and recombinant proteins. After foam fractionation, alone and with bovine serum albumin and Triton X-100 as pro-foaming agents, FITC-labeled endotoxin remains in the bulk solution. These studies suggest that foam fractionation will be ineffective in the purification of plasmid DNA solutions, which are not surface-active and remain in the bulk solution with endotoxin. These data support the use of foam fractionation as an effective method for separating surface-active recombinant proteins, which will concentrate in the foam, away from endotoxin.     

Anti-inflammatory therapies in sepsis and septic shock

Despite advances in supportive care, the morbidity and mortality rate resulting from sepsis and septic shock remain high (30 - 50%). A central hypothesis driving sepsis research in recent years is that this syndrome is the result of excessive inflammation. Therapies designed to inhibit the inflammatory response were first shown to be markedly beneficial in animal models of sepsis and then tested in numerous clinical trials involving thousands of patients. Three broad anti-inflammatory strategies have been investigated. First, glucocorticoids in high doses administered at the onset of sepsis were studied. This approach proved unsuccessful. More recently, however, glucocorticoids in lower doses have been found to have a beneficial effect in patients with septic shock. Whether the mechanism of this treatment benefit is through inhibition of inflammation, or by counteracting a relative steroid refractoriness occurring during sepsis, remains unknown. The next focus of research were agents active against the endotoxin molecule. However, as with the experience with glucocorticoids, this approach lacked a consistent pattern of efficacy. It is unclear if this lack of efficacy is the result of endotoxin being a poor therapeutic target, or from testing agents which lacked the appropriate biological activity. Most recently, clinical trials in sepsis have focused on inhibiting specific host pro-inflammatory mediators (e.g., TNF, interleukins). While individual trials of inhibitors of these pro-inflammatory mediators failed to show a convincing benefit, pooling the results of these trials suggest that this approach has a marginal effect, supporting a role for excessive inflammation in sepsis. An unanswered question is reconcilling the very favourable effects obtained with anti-inflammatory treatments in animal models with the marginal results in humans. Further clinical and laboratory research is needed and may provide insight into more effective ways to use the anti-inflammatory agents already tested, or to investigate other potentially more effective anti-inflammatory agents in this syndrome.     

Anti-inflammatory therapies in sepsis and septic shock

Despite advances in supportive care, the morbidity and mortality rate resulting from sepsis and septic shock remain high (30 - 50%). A central hypothesis driving sepsis research in recent years is that this syndrome is the result of excessive inflammation. Therapies designed to inhibit the inflammatory response were first shown to be markedly beneficial in animal models of sepsis and then tested in numerous clinical trials involving thousands of patients. Three broad anti-inflammatory strategies have been investigated. First, glucocorticoids in high doses administered at the onset of sepsis were studied. This approach proved unsuccessful. More recently, however, glucocorticoids in lower doses have been found to have a beneficial effect in patients with septic shock. Whether the mechanism of this treatment benefit is through inhibition of inflammation, or by counteracting a relative steroid refractoriness occurring during sepsis, remains unknown. The next focus of research were agents active against the endotoxin molecule. However, as with the experience with glucocorticoids, this approach lacked a consistent pattern of efficacy. It is unclear if this lack of efficacy is the result of endotoxin being a poor therapeutic target, or from testing agents which lacked the appropriate biological activity. Most recently, clinical trials in sepsis have focused on inhibiting specific host pro-inflammatory mediators (e.g., TNF, interleukins). While individual trials of inhibitors of these pro-inflammatory mediators failed to show a convincing benefit, pooling the results of these trials suggest that this approach has a marginal effect, supporting a role for excessive inflammation in sepsis. An unanswered question is reconcilling the very favourable effects obtained with anti-inflammatory treatments in animal models with the marginal results in humans. Further clinical and laboratory research is needed and may provide insight into more effective ways to use the anti-inflammatory agents already tested, or to investigate other potentially more effective anti-inflammatory agents in this syndrome.     

Compared studies of antimicrobial agents against E. coli, Klebsiella, Citrobacter and Proteus isolated from urinary tract infections

In vitro activities of antibacterial agents against E. coli, Klebsiella, Citrobacter and Proteus which were isolated from patients urinary tract infections at 8 hospitals in Japan, were investigated by agar dilution method from July to October in 1979. The summarized results are as follows. 1. Among oral antibacterial agents, MPC and PPA have showed potent antibacterial activities against E. coli and Klebsiella. Among parenteral antibiotics, CTM was the most active against E. coli and Klebsiella. However, ABPC-resistant E. coli and Klebsiella have appeared to occupy about 40% and 96% of bacteria isolated from urinary tract infections, respectively. 2. In vitro activities of antibacterial agents against Proteus and Citrobacter showed not so potent. 3. Causative organisms in female patients with simple urinary tract infections were mainly E. coli and Klebsiella. 4. Among oral antibacterial agents, PPA have shown similar antimicrobial activities against E. coli isolated from simple and complicated urinary tract infections. ABPC and MPC have been influenced in some degree by these factors. However, parenteral antibiotics are not influenced by these factors. On the other hand, in vitro activities of antibacterial agents against Klebsiella isolated from simple and complicated urinary tract infections were similar.     

The effect of streptozotocin diabetes on endotoxicosis in mice

Repeated injections of streptozotocin (SZN), to a total of 5 mg, produced a state of diabetes in mice without alteration in various parameters of the reticuloendothelial system (RES). This was associated with hyperreactivity to endotoxin lethality which decreased with time and which could not be correlated with blood glucose levels in SZN injected animals. One single injection of SZN, too, sensitized animals to endotoxin death, albeit less effectively than after repeated administration of small doses, although the effect was dose dependent. Impairment of protection by cortisol against endotoxin lethality in mice was less severe after a single injection of SZN vs administration of an equivalent amount of SZN divided over a 5 day period. Blood glucose levels diminished very rapidly after endotoxin administration and were only partially reversed during cortisol protection against the lethal effects of endotoxin in SZN pretreated animals. Streptozotocin impaired the induction of tolerance to endotoxin but not the activation of the RES that accompanies tolerance. It is suggested that the influence of various pharmacological agents that reverse SZN diabetes may form a new model to elucidate the pathophysiology of endotoxicosis.     

Protective effects of urinary trypsin inhibitor in experimental shock

The effects of human urinary trypsin inhibitor (UTI) were studied in experimental shock models. Administration of 50,000 U/kg, i.v., of UTI protected against mortality from shock induced by burn, endotoxin or trauma. Aprotinin at a dose of 50,000 U/kg improved only endotoxin shock and showed a moderate but not significant effect on burn and traumatic shock. Administration of 50,000 U/kg, i.v., of UTI protected against the aggravation in systemic hemodynamics in canine hemorrhagic shock. Furthermore, in rat traumatic shock, 50,000 U/kg, i.v., administration of UTI significantly reversed the increased serum beta-glucuronidase and trypsin activities and the decreased hepatic ATP level, and it moderately suppressed the increased serum uric acid level. Aprotinin failed to affect all these biochemical changes induced by drum trauma. These results suggest that the protective effect of UTI against experimental shock is possibly exerted through lowering the elevated enzyme activities in the serum during shock.     

Thioguanine, mercaptopurine: their analogs and nucleosides as antimetabolites

6-Mercaptopurine (6MP) and 6-thioguanine (6TG) are analogs of the natural purines: hypoxanthine and guanine. Both mercaptopurine and thioguanine are substrates for hypoxanthine-guanine phosphoribosyltransferase and are converted into the ribonucleotides 6-thioguanosine monophosphate (6-thioGMP) and 6-thioinosine monophosphate (T-IMP) respectively. The accumulation of these monophosphates inhibits several vital metabolic reactions. Today, these thiopurine bases remain valuable agents for the induction and maintenance of remissions in patients with myelocytic and acute lymphocytic leukemia. Despite their proved clinical importance, 6MP and 6TG have certain therapeutic disadvantages, which have continued to stimulate the search for purine derivatives enhancing therapeutic efficacy. Considerable efforts have been made to prepare other novel mercaptopurine and thioguanine analogs and their nucleosides to improve the antitumor efficacy. The effectiveness of these thiopurines against certain tumor cell lines suggested that some of these mercaptopurine analogs and their nucleosides would be worthy of consideration in order to determine whether they exert a more selective effect against neoplastic cells than against normal cells or they might be useful in patients whose disease has become resistant to 6MP or 6TG. This review will focus on mercaptopurine analogs and their nucleosides as antimetabolite agents.     

麻醉药的抗炎抗感染功效及其作用靶点研究进展

除在手术中发挥止痛与肌松弛等作用外,麻醉药的抗急性炎症和抗感染的功效日益受到关注,尤其是对内毒素血症及内毒素性休克动物的保护作用.研究显示不同的麻醉药具有不同的精确作用靶点,因此推测麻醉药的抗炎抗感染作用机制也不完全一样.本文主要介绍麻醉药的抗炎抗感染功效及其作用靶点研究进展.     

Drug-induced oesophageal disorders: pathogenesis, incidence, prevention and management.

Drug-induced injury of the oesophagus is a common cause of oesophageal complaints. 'Pill-induced' oesophagitis is associated with the ingestion of certain drugs and accounts for many cases of erosive oesophagitis. To date, more than 70 drugs have been reported to induce oesophageal disorders. Antibacterials such as doxycycline, tetracycline and clindamycin are the offending agents in more than 50% of cases. Other commonly prescribed drugs that cause oesophageal injury include aspirin (acetylsalicylic acid), potassium chloride, ferrous sulfate, quinidine, alprenolol and various steroidal and nonsteroidal anti-inflammatory agents. However, many physicians and even more patients are not aware of this problem. Capsules or tablets are commonly delayed in their passage through the oesophagus. Highly caustic coatings, direct medication injury and poor oesophageal clearance of pills can lead to acute inflammation. Oesophageal damage occurs when the caustic contents of a drug remain in the oesophagus long enough to produce mucosal lesions. Taking medications at bedtime or without fluids is a common cause of oesophagitis. The possibility of drug-related damage should be suspected in all cases of oesophagitis, chest pain and dysphagia. History and gastrointestinal endoscopy will confirm the diagnosis. Treatment is supportive, although acid reduction is used frequently as an adjunct. This review reflects the current state of knowledge in this field.     

Antibody immunotherapy of gram-negative bacterial sepsis

Gram-negative bacterial sepsis continues to represent a significant cause of morbidity and mortality in hospitalized patients. Currently available medical therapy (antimicrobial agents, hemodynamic monitoring, aggressive fluid resuscitation, and nutritional support) for this disease process has reduced but not eliminated the severe consequences that may ensue. Recent investigations have demonstrated the ability of antibody directed against gram-negative bacterial lipopolysaccharide (LPS or endotoxin) to afford protection during experimental gram-negative bacillary sepsis. The core LPS-lipid A portion of endotoxin represents a determinant shared by many common gram-negative microorganisms that is luxuriantly expressed on the cell surface of rough mutants of Escherichia coli and Salmonella minnesota. These organisms or the outer membrane LPS isolated from them thus represent suitable immunogens for the development of cross-protective antibody preparations. Large quantities of highly cross-reactive antibody may potentially be obtained from several sources: murine or human monoclonal antibodies, immunization of large animals or humans with subsequent plasmapharesis and antibody isolation, affinity purification of large amounts of normal antibody, and pooling of prescreened lots of normal animal or human antibody that react to a particular bacterial antigen.