Orthopedic Surgery and Anesthesiology Surgical Improvement Strategies Project-Phase II Outcomes

BACKGROUND

Our institution previously initiated a perioperative surgical home initiative to improve quality and efficiency across the hospital arc of care of primary total knee arthroplasty and total hip arthroplasty patients. Phase II of this project aimed to (1) expand the perioperative surgical home to include revision total hip arthroplasties and total knee arthroplasties, hip preservation procedures, and reconstructions after oncologic resections; (2) expand the project to include the preoperative phase; and (3) further refine the perioperative surgical home goals accomplished in phase I.

METHODS

Phase II of the Orthopedic Surgery and Anesthesiology Surgical Improvement Strategies project ran from July 2018 to July 2019. The evaluated arc of care spanned from the preoperative surgical consult visit through 90 days postoperative in the expanded population described above.

RESULTS

Mean length of stay decreased from 2.2 days to 2.0 days (P < .001), 90-day readmission decreased from 3.0% to 1.6% (P < .001), and Press-Ganey scores increased from 77.1 to 79.2 (97th percentile). Mean and maximum pain scores and opioid consumption remained unchanged (lowest P = .31). Annual surgical volume increased by 10%. Composite changes in surgical volume and cost reductions equaled $5 million.

CONCLUSION

Application of previously successful health systems engineering tools and methods in phase I of Orthopedic Surgery and Anesthesiology Surgical Improvement Strategies enabled additional evolution of an orthopedic perioperative surgical home to encompass more diverse and complex patient populations while increasing system-wide quality, safety, and financial outcomes. Improved process and outcomes metrics reflected increased efficiency across the episode of care without untoward effects.

LEVEL OF EVIDENCE

III Therapeutic.

Orthopedic Surgery and Anesthesiology Surgical Improvement Strategies Project: Phase I Outcomes

BACKGROUND

This study aimed to improve institutional value-based patient care processes, provider collaboration, and continuous process improvement mechanisms for primary total hip arthroplasties and total knee arthroplasties through establishment of a perioperative orthopedic surgical home.

METHODS

On June 1, 2017, an institutionally sponsored initiative commenced known as the orthopedic surgery and anesthesiology surgical improvement strategy project. A multidisciplinary team consisting of orthopedic surgeons, anesthesiologists, advanced practice providers, nurses, pharmacists, physical therapists, social workers, and hospital administration met regularly to identify areas for improvement in the preoperative, intraoperative, and post-anesthesia care unit, and postoperative phases of care.

RESULTS

Mean hospital length of stay decreased from 2.7 to 2.2 days (P < .001), incidence of discharge to a skilled nursing facility decreased from 24% to 17% (P = .008), and the number of patients receiving physical therapy on the day of surgery increased from 10% to 100% (P < .001). Press-Ganey scores increased from 74.9 to 75.8 (94th percentile), while mean and maximum pain scores, opioid consumption, and hospital readmission rates remained unchanged (lowest P = .29). Annual total hip arthroplasty and total knee arthroplasty surgical volume increased by 11.4%. Decreased hospital length of stay and increased surgical volume yielded a combined annual savings of $2.5 million across the 9 involved orthopedic surgeons.

CONCLUSION

Through application of perioperative surgical home tools and concepts, key advances included phase of care integration, enhanced data management, decreased length of stay, coordinated perioperative management, increased surgical volume without personnel additions, and more efficient communication and patient care flow across preoperative, intraoperative, and postoperative phases.

LEVEL OF EVIDENCE

III Therapeutic.

The impact of effective paediatric adherence promotion interventions: systematic review and meta-analysis

BACKGROUND

Understanding the impact of effective paediatric adherence promotion interventions on patients, families and the healthcare system is necessary to inform efforts to improve healthcare quality and control costs. Building on previous research suggesting that improving adherence may have far-reaching benefits, the objective of this study was to quantify the impact of effective adherence promotion interventions for children and adolescents with a chronic medical condition on patients, families and the healthcare system.

METHODS

Authors systematically reviewed articles indexed in PubMed, PsycINFO and CINAHL to identify randomized controlled trials of paediatric adherence promotion interventions. Interventions that improved paediatric adherence and examined patient-level, family-level or healthcare system-level outcomes in children and adolescents (M age ≤ 18 years) with a chronic medical condition were included. Two authors independently extracted and classified outcome variables as patient-level (quality of life and disease-related activity restrictions), micro-level (family functioning, family conflict, caregiver quality of life, caregiver sleep interruption, caregiver days away from work and patient missed school days) or macro-level variables (emergency department visits, hospitalizations, outpatient visits and urgent care visits). Outcome variables detailed in previously published reviews (i.e. disease severity) were excluded.

RESULTS

Twenty studies representing 19 unique samples met inclusion criteria. An additional eight articles representing trials that did not significantly improve adherence were included in post hoc analyses. Compared with control interventions, effective paediatric adherence promotion interventions improved patient quality of life and family-level outcomes and decreased healthcare utilization among children and adolescents with a chronic medical condition.

CONCLUSIONS

Interdisciplinary efforts to improve healthcare quality and reduce spending among children and adolescents with a chronic medical condition may be enhanced by incorporating effective paediatric adherence promotion interventions. As relatively few chronic medical conditions were represented in included studies, future research should examine the impact of paediatric adherence promotion interventions in other populations.

Clinical and economic outcomes after introduction of drug-eluting stents

BACKGROUND

In clinical trials, drug-eluting stents (DES) improve clinical outcomes but are more expensive than bare-metal stents (BMS).

OBJECTIVE

To assess clinical and economic outcomes of all percutaneous coronary intervention (PCI) procedures in a general interventional cardiology practice before and after DES introduction in 2003.

METHODS

We identified all patients undergoing PCI in 2000-2002 (early cohort, pre-DES era) and from 2004 through April 31, 2006 (late cohort, DES era) in a large PCI registry. Logistic and Cox proportional hazard models estimated the risk of adverse events; generalized linear modeling predicted economic outcomes.

RESULTS

We compared 4303 early-cohort patients with 3422 late-cohort patients. Most early-cohort patients (90%) had BMS implanted; the rest had atherectomy or balloon angioplasty only. Among late-cohort patients, 83% had DES, 14% BMS, and 6% balloon angioplasty or atherectomy only. In-hospital adverse-event rates and incidence of death or myocardial infarction (during a median follow-up of 22 months) were similar. Follow-up procedures were significantly fewer in the later era (hazard ratio for target lesion revascularization: 0.58; 95% confidence interval [CI], 0.50-0.68). Although catheterization lab supply costs were higher in the DES era, length of stay following index PCI and overall practice costs were reduced, on average, 0.40 days and $2053 in the late cohort (95% bootstrapped CI of adjusted mean difference, -$2937 to -$1197). Follow-up cardiac hospitalization costs were similar at 1 year.

CONCLUSIONS

Patients undergoing PCI following DES introduction experienced improved clinical outcomes during follow-up and reduced overall procedural costs, despite higher stent acquisition costs.

Health-related quality of life in college students with and without childhood-onset asthma

OBJECTIVE

The current study investigated whether differences existed in health-related quality of life between individuals who self-identified as having childhood-onset asthma and individuals without a chronic illness. Additionally, the relationship between perceived illness intrusiveness and illness uncertainty to health-related quality of life was explored.

METHODS

College undergraduates at least 18 years of age who self-identified as having childhood asthma were randomly matched by age and gender to healthy control participants. Participants completed a demographic form, the Mishel Uncertainty in Illness Scale-Community Form, the Illness Intrusiveness Scale, and the SF-36 Health Survey, a measure of health-related quality of life.

RESULTS

Participants with asthma had significantly lower scores on the total and mental health-related quality of life scales than did healthy control subjects. There were no significant differences between self-identified participants with asthma and matched healthy control subjects on physical health-related quality of life scales. Illness intrusiveness was not related to either the physical (e.g., physical functioning, general health) or mental health-related quality of life. Higher levels of illness uncertainty were significantly related to higher levels of mental health-related quality of life (e.g., vitality, mental health). In addition, participants with asthma scored significantly lower than healthy controls on the social functioning and role-emotional subscales.

CONCLUSION

The current study adds to the extant literature by examining the relationships between illness intrusiveness, illness uncertainty, and health-related quality of life among a young adult population. College students with asthma appear to be at risk for diminished quality of life compared to a healthy comparison group. Further examination of various domains of health-related quality of life among older adolescents and young adults with childhood asthma is needed.

Post-treatment skin reactions reported by cancer patients differ by race, not by treatment or expectations

Cancer patients may experience skin problems while undergoing chemotherapy and radiation therapy. Frequency of skin reactions may be influenced by skin pigmentation and psychological factors. A Symptom Inventory completed by 656 cancer patients nationwide before and after chemotherapy, radiation therapy, or chemotherapy plus radiation therapy was analysed to determine if treatment type, race (Black vs White), and pretreatment expectations influenced post-treatment skin reactions. Subsequent analysis of a local Symptom Inventory completed weekly for 5 weeks by 308 patients receiving radiation therapy examined severity of reported skin reactions. Significantly more patients receiving radiation therapy had stronger expectations of skin problems (62%) than patients receiving chemotherapy (40%, P=0.001) or chemotherapy plus radiation therapy (45%, P=0.003). Overall, expectations did not correlate with patient reported post-treatment skin problems in white (r=0.014, P=0.781) or black (r=0.021, P=0.936) patients. Although no significant difference was found between black and white patients in their pretreatment expectations of skin problems (P=0.32), black patients (10 out of 18, 56%) reported more skin problems than white patients (90 out of 393, 23%, P=0.001). Similarly, the local study showed that significantly more black patients (1 out of 5, 20%) reported severe skin reactions at the treatment site than white patients (12 out of 161, 8%). A direct correlation was observed between severity of skin problems and pain at the treatment site (r=0.541, P<0.001). Total radiation exposure did not significantly correlate with the report of skin problems at the treatment site for white or black patients. Overall, black patients reported more severe post-treatment skin problems than white patients. Our results suggest that symptom management for post-treatment skin reactions in cancer patients receiving radiation treatment could differ depending on their racial background.

Initial experience with the cardiva Boomerang™ vascular closure device in diagnostic catheterization

OBJECTIVES

The authors studied the safety and efficacy of the Cardiva Boomerang vascular closure device in patients undergoing diagnostic cardiac catheterization.

BACKGROUND

Conventional vascular closure devices (sutures, collagen plugs, or metal clips) have been associated with catastrophic complications including arterial occlusion and foreign body infections; furthermore, they cannot be utilized in patients with peripheral vascular disease or vascular access site in a vessel other than the common femoral artery. The Cardiva Boomerang device facilitates vascular hemostasis without leaving any foreign body behind at the access site, can be used in peripheral vascular disease, and can be used in vessels other than the common femoral artery

METHODS

A total of 96 patients undergoing transfemoral diagnostic cardiac catheterization were included in this study, including 25 (26%) patients with contraindications to conventional closure devices. Femoral angiography was performed prior to deployment of the Cardiva Boomerang closure device. Patients were ambulated at 1 hr after hemostasis was achieved.

RESULTS

The device was successfully deployed and hemostasis achieved with the device alone in 95 (99%) patients. The device failed to deploy in 1 (1%) patient and required conversion to standard manual compression. Minor complications were observed in 5 (5%) patients. No patients experienced major complications including femoral hematoma > 4 cm, red blood cell transfusion, retroperitoneal bleed, arteriovenous fistula, pseudoaneurysm, infection, arterial occlusion, or vascular surgery.

CONCLUSIONS

The Cardiva Boomerang device is safe and effective in patients undergoing diagnostic cardiac catheterization using the transfemoral approach, facilitating early ambulation with low rates of vascular complications.

Cancer immunotherapy by fusions of dendritic and tumour cells and rh-IL-12

BACKGROUND

Vaccination with fusion cells (FCs) comprising dendritic cells and tumour cells as well as administration of interleukin-12 (IL-12) showed a significant therapeutic effect against established tumours in mouse experimental models. We conducted immunotherapy against various malignant tumours using the FCs and rhIL-12, and investigated the safety and efficacy of the therapy.

MATERIALS AND METHODS

Patients' DCs were mixed with autologous irradiated tumour cells and treated with 50% polyethylene glycol to generate FCs. The FCs were inoculated intradermally, and then 30 ng kg(-1) of rhIL-12 was injected at the same sites 2 and 6 days later. This process was carried out as one cycle, and three of these cycles were repeated at 1-week intervals to comprise one course. After completing the course, its safety and therapeutic effects were estimated.

RESULTS

The most frequently observed adverse event was fever, observed in 26% of patients in the first cycle. Decrease in white blood cell and an increase in serum ALT were observed in 28% and 25%, respectively. Three out of 12 patients with a malignant brain tumour (25%) achieved a partial response (PR), but other patients with a malignant tumour showed no regression of their tumours. Thirteen out of 16 patients with a brain tumour (81%) showed cutaneous delayed hypersensitivity responses. However, only one of 16 patients (6%) with a malignant tumour other than a brain tumour developed such responses.

CONCLUSIONS

Immunotherapy using a FC vaccine and rhIL-12 induced no serious adverse reactions, and provided good therapeutic responses in some of the patients with a brain tumour.

Targeted mutagenesis of Smad1 reveals an essential role in chorioallantoic fusion

The Smad family of intracellular signaling intermediates transduce signals downstream from the transforming growth factor beta (TGF-beta) family of receptor serine threonine kinases. The original member of this family, Smad1, has been shown to mediate signals from receptors for the bone morphogenetic proteins (BMPs), a large group of ligands in the TGF-beta superfamily that mediate important developmental events. We have targeted the Smad1 gene in mice and created mutants null at this locus. Smad1 mutant mice die at approximately 9.5 days postcoitum due to defects in allantois formation. In Smad1 mutant mice, the allantois fails to fuse to the chorion, resulting in a lack of placenta and failure to establish a definitive embryonic circulation. Although vasculogenesis is initiated in the mutant allantois, the vessels formed are disorganized, and VCAM-1 protein, a marker for distal allantois development, is not expressed. Smad1 null fibroblasts are still able to respond to BMP2, however, suggesting that the defect observed in the developing extraembryonic tissue is caused by a very specific loss of transcriptional activity regulated by Smad1. Our data further demonstrate that although highly similar structurally, Smad proteins are not functionally homologous.

Differences in splenic B-lymphocyte ganglioside expression and accessibility in normal and endotoxin-hyporesponsive mice

Endotoxin-responsive (C3H/HeN) and -hyporesponsive (C3H/HeJ) murine B lymphocytes purified by adherence to anti-immunoglobulin ("antibody panning") possess identical gangliosides but different ganglioside surface accessibilities. We investigated the distribution and surface accessibility of gangliosides of B lymphocytes purified by adherence to plastic ("plastic panning") or by subtraction of non-B-lymphocyte components. As with antibody panning, there were no entirely new or absent gangliosides in plastic-panned or subtraction-purified B lymphocytes of each strain. However, striking changes in relative expression of five gangliosides were detected with each purification protocol. Moreover, five gangliosides of antibody-panned and plastic-panned B lymphocytes but only two gangliosides of subtraction-purified B lymphocytes were inaccessible to surface labeling. Unlike the situation for antibody-panned B lymphocytes, no interstrain (HeN vs. HeJ) surface accessibility differences existed in gangliosides of plastic-panned or subtraction-purified cells. Exposure of subtraction-purified B lymphocytes to anti-immunoglobulin failed to elicit changes in ganglioside expression. Murine B lymphocytes have distinct protocol-dependent differences in glycolipid phenotype which likely denote individual subpopulations.

A comparative trial of imipenem versus ceftazidime in the release of endotoxin and cytokine generation in patients with gram-negative urosepsis. Urosepsis Study Group

Evidence from in vitro experiments and animal and human studies indicate that antibiotic therapy may induce the release of endotoxin from the outer membrane of Gram-negative bacteria. Antibiotics that bind preferentially to penicillin-binding protein-2 (PBP-2)--such as imipenem--are associated with little release of endotoxin, while antibiotics that preferentially bind to PBP-3--such as ceftazidime--are associated with far greater release of endotoxin. We conducted a randomized, multicenter, double-blind study comparing imipenem to ceftazidime in patients with urinary tract infections caused by Gram-negative bacilli associated with signs and symptoms of systemic inflammation. A total of 33 patients were randomized to receive either imipenem (n = 14) or ceftazidime (n = 19) for initial treatment for urosepsis. No differences in plasma endotoxin, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) or urine endotoxin, IL-6 or IL-8 levels were found between the two treatment groups within the first 8 h after antibiotic administration. We conclude that, if differences exist with respect to endotoxin release by these two antimicrobial agents, these differences are not readily demonstrable in this clinical study with carefully defined patients with Gram-negative urinary tract infections.

Nep1 Protein from Fusarium oxysporum Enhances Biological Control of Opium Poppy by Pleospora papaveracea

ABSTRACT The fungus Pleospora papaveracea and Nep1, a phytotoxic protein from Fusarium oxysporum, were evaluated for their biocontrol potential on opium poppy (Papaver somniferum). Four treatments consisting of a control, P. papaveracea conidia, Nep1 (5 mug/ml), and P. papaveracea conidia plus Nep1 (5 mug/ml) were used in detached-leaf and whole-plant studies. Conidia of P. papaveracea remained viable for 38 days when stored at 20 or 4 degrees C. Nep1 was stable in the presence of conidia for 38 days when stored at 4 degrees C or for 28 days at 20 degrees C. The presence of Nep1 did not affect conidia germination or appressoria formation. Nep1 was recovered from drops applied to opium poppy leaves in greenhouse and field studies 24 h after treatment. Opium poppy treated with the combination of Nep1 and P. papaveracea had higher necrosis ratings than the other treatments. There were changes in the intercellular protein profiles, determined by sodium dodecyl sulfate gel electrophoresis and silver staining, due to application of treatments; the most intense occurred in response to the combination of Nep1 and P. papaveracea. The combination of Nep1 and P. papaveracea enhanced the damage caused to opium poppy more than either component alone.

Effects of single-dose interleukin-12 exposure on interleukin-12-associated toxicity and interferon-gamma production

Interleukin-12 (IL-12) is a key regulator of cell-mediated immunity that has therapeutic potential in cancer and infectious disease. In a previous Phase 1 dose escalation study of a single test dose of recombinant human IL-12 (rhIL-12) followed 14 days later by cycles of five consecutive daily intravenous injections every 3 weeks, we showed that a dose level up to 500 ng/kg could be administered with acceptable levels of safety. Based on these results, a Phase 2 study was conducted. In the Phase 2 study, however, administration of rhIL-12 at this same dose level resulted in severe toxicities with some patients unable to tolerate more than two successive doses. Of the 17 patients receiving rhIL-12 in the Phase 2 study, 12 patients were hospitalized and two patients died. A thorough scientific investigation to determine the cause of this unexpected toxicity failed to identify any difference in the drug products used or the patient populations enrolled in the Phase 1 and Phase 2 studies that could have accounted for the profound difference in toxicity. The focus of the investigation therefore shifted to the schedule of rhIL-12 administration. We determined that a single injection of rhIL-12 2 weeks before consecutive dosing included in the Phase 1 study, but not in the schedule of administration in the Phase 2 study, has a profound abrogating effect on IL-12-induced interferon-gamma (IFN-gamma) production and toxicity. This observation of schedule-dependent toxicity of IL-12 has been verified in mice, as well as nonhuman primates. In this regard, a single injection of IL-12 before consecutive daily dosing protected mice and cynomolgus monkeys from acute toxicity including mortality and was associated with an attenuated IFN-gamma response. Because of this unique biologic response, careful attention to the schedule of administration is required to assure safe and effective clinical development of this highly promising cytokine.

Hyperbaric oxygen therapy for acute ankle sprains

We conducted a randomized double-blind study of 32 subject with acute ankle sprains to compare treatment with hyperbaric oxygen at 2 atmospheres absolute pressure (N = 16) (treatment group) with treatment with air at 1.1 atmosphere absolute pressure (N = 16) (control group) in a hyperbaric chamber. Each group received three treatments at their respective pressures: one for 90 minutes and two for 60 minutes each. Mean age, severity grade, and time to treatment (treatment group, 34.3 +/- 6.3 hours; control group, 32.6 +/- 4.6 hours) were similar in both groups. Joint function measured by a functional index improved from 0.40 +/- 0.2 to 6.3 +/- 0.4 with hyperbaric oxygen and from 0.8 +/- 0.3 to 5.3 +/- 0.6 with air. The change from initial to final evaluation was significantly greater in the treatment group. Foot and ankle volume by water displacement decreased from 1451 +/- 57 ml to 1425 +/- 63 ml with hyperbaric oxygen and from 1403 +/- 50 ml of 1371 +/- 45 ml with air (no difference was noted between hyperbaric oxygen treatment and air treatment using a two-day analysis of variance). Subjective pain index fell from 3.3 +/- 0.5 to 0.8 +/- 0.3 with hyperbaric oxygen and from 2.6 +/- 0.3 to 0.3 +/- 0.2 with air. No differences were noted in passive or active range of motion when comparing hyperbaric oxygen treatment with air treatment. Time to recovery was the same in both groups (treatment, 16.0 +/- 6.3 days; control, 15.4 +/- 2.8 days). Regression analysis to determine the influence of time to treatment, initial severity of injury, hyperbaric oxygen, and age showed no effect of hyperbaric oxygen treatment on time to recovery.

Activation of murine lymphocytes by lipopolysaccharide incorporated in fusogenic, reconstituted influenza virus envelopes (virosomes)

We have studied the in vitro activation of murine lymphocytes with LPS incorporated in the membranes of both phospholipid vesicles (liposomes) and vesicles composed of fusogenic, reconstituted influenza virus envelopes (virosomes). The incorporation of Salmonella minnesota rough-LPS in liposomes reduced the potency of LPS to stimulate splenocyte proliferation and cell surface kappa-light chain expression on 70 Z/3 pre-B cells by over 100-fold. Salmonella minnesota rough-LPS inserted into virosomes was at least 10-fold more potent than free LPS, both when prebound virosomes were allowed to be taken up by the cells at neutral pH and when the virosomes were fused into the plasma membrane by low pH treatment. Inactivation of the virosomes by low pH pretreatment reduced the potency of the virosomal LPS to the level of liposome-incorporated LPS. The association of the various LPS forms with the cells was quantitated using radio-iodinated LPS. Correcting for uptake, virosomal LPS remained 2- to 10-fold more potent than free LPS in stimulating B lymphocytes and at least 100-fold more active than liposomal LPS or fusion-inactivated virosomes. After low pH-induced fusion with the plasma membrane, the majority (80%) of the prebound virosomes had fused with the cells, compared with about 8% after neutral uptake. From these results we conclude that LPS inserted into the plasma or endosomal membranes efficiently activates murine lymphocytes. The fusion data suggest that the incorporation into endosomal membranes might be a more effective stimulus.

Activation of murine lymphocytes by lipopolysaccharide incorporated in fusogenic, reconstituted influenza virus envelopes (virosomes)

We have studied the in vitro activation of murine lymphocytes with LPS incorporated in the membranes of both phospholipid vesicles (liposomes) and vesicles composed of fusogenic, reconstituted influenza virus envelopes (virosomes). The incorporation of Salmonella minnesota rough-LPS in liposomes reduced the potency of LPS to stimulate splenocyte proliferation and cell surface kappa-light chain expression on 70 Z/3 pre-B cells by over 100-fold. Salmonella minnesota rough-LPS inserted into virosomes was at least 10-fold more potent than free LPS, both when prebound virosomes were allowed to be taken up by the cells at neutral pH and when the virosomes were fused into the plasma membrane by low pH treatment. Inactivation of the virosomes by low pH pretreatment reduced the potency of the virosomal LPS to the level of liposome-incorporated LPS. The association of the various LPS forms with the cells was quantitated using radio-iodinated LPS. Correcting for uptake, virosomal LPS remained 2- to 10-fold more potent than free LPS in stimulating B lymphocytes and at least 100-fold more active than liposomal LPS or fusion-inactivated virosomes. After low pH-induced fusion with the plasma membrane, the majority (80%) of the prebound virosomes had fused with the cells, compared with about 8% after neutral uptake. From these results we conclude that LPS inserted into the plasma or endosomal membranes efficiently activates murine lymphocytes. The fusion data suggest that the incorporation into endosomal membranes might be a more effective stimulus.

Drowning prevention. A case study in EMS epidemiology

A central theme for EMS systems is the reduction of death and disability from emergency illnesses and injuries, with most systems focusing exclusively on treatment to fulfill their missions. Unfortunately, this has often resulted in the neglect or complete disregard of prevention, which actually may be the more powerful intervention strategy. Yet hopefully, as EMS systems begin to learn and embrace the principles of continuous quality improvement (CQI) in their organizational cultures, the advantages of prevention vs. treatment will become more apparent and internally recognized.

Anti-PRP antibody levels after a primary series of PRP-OMPC and persistence of antibody titres following primary and booster doses

The Haemophilus influenzae capsular polysaccharide-outer membrane protein conjugate, PRP-OMPC (PedvaxHIB) elicits very good antibody responses in infants > or = 2 months of age after the first dose. Increasing age at time of first vaccination correlates with higher antibody responses. Anti-PRP responses are consistently high with the first injection among all population groups studied. Booster doses stimulate anamnestic antibody responses after one year of age. Among US children (excluding Navajo and Apache children) given a primary injection at 14-18 months of age, the geometric mean titre (GMT) after 2 to 3 years was > 1 micrograms/ml. US children (excluding Navajo and Apache children) given a primary series at 2 and 4 months of age and a booster at 18 months of age also had an anti-PRP GMT > 1 micrograms/ml 2.5 years later. Navajo and Apache children given a primary series at 2 and 4 months of age and a booster at 12-15 months had antibody levels of 1.50 micrograms/ml one year later. Antibody persistence data suggest there will be long-term protection against Haemophilus influenzae b disease following immunization with PRP-OMPC.

Murine peritoneal macrophage gangliosides inhibit lymphocyte proliferation

Gangliosides have been shown to act as immunoregulatory agents by altering proliferative responses of lymphocytes to both antigens and mitogens. Most early studies have utilized brain gangliosides and have required high concentrations. The role of endogenous gangliosides from macrophages has remained unexplored. In this study, thioglycolate-elicited murine peritoneal macrophage gangliosides were purified and added to cultures of murine lymphocytes. Nanogram amounts caused a profound inhibition of LPS-induced DNA synthesis of splenocytes and of purified B lymphocytes, without demonstrable cellular toxicity. No effect was seen using asialo-GM1. This effect was present across a wide range of lipopolysaccharide (LPS) doses. Nanogram amounts of macrophage gangliosides also inhibited concanavalin A (ConA)-mediated lymphocyte proliferation. Inhibition of LPS-induced mitogenesis was present even if gangliosides were removed from the extracellular environment after 15-60 min of incubation prior to the addition of LPS. This inhibition was reversible with incubation of ganglioside pre-treated lymphocytes in medium containing serum. These inhibitory properties of macrophage gangliosides are distinct from those found in studies using brain gangliosides, and support a potential role for macrophage gangliosides as negative modulators of lymphocyte proliferation.

The presence of sialidase-sensitive sialosylgangliotetraosyl ceramide (GM1b) in stimulated murine macrophages. Deficiency of GM1b in Escherichia coli-activated macrophages from the C3H/HeJ mouse

The stimulated murine macrophage was found to contain 11 major gangliosides of which 8 were determined to be monosialylated. The thin-layer chromatographic patterns were complicated by the presence of both sialic acid and ceramide fatty acid heterogeneity. N-glycolyl and N-acetylneuraminic acid-containing species were present for each ganglioside characterized. Although C18 sphingosine was the only long chain base detected, ceramide fatty acid ranged from C16 to C24 carbon moieties. Based on gas-liquid chromatographic and antibody analyses, all major tetraosyl structure gangliosides were ganglio series types. Comprising 43 to 60% of thioglycollate-stimulated cells and 60 to 70% of Escherichia coli-activated cells, monosialosyl-gangliotetraosyl ceromides (Gm1 gangliosides) were the major monosialo species of which four were present: sialidase-resistant NeuGc-GM1a and NeuAc-GM1a and sialidase sensitive NeuGc-GM1b and NeuAc-GM1b. Analyses of thioglycollate-elicited murine peritoneal macrophage ganglioside patterns from four strains of mice, including the C3H/HeJ strain, indicated that, in the absence of any expression of a genetic defect, the pattern is conserved. However, when E. coli was used as the activating agent, the normal C3H/HeN macrophage contained little Gm1a with the sialidase-sensitive Gm1b predominant; the converse was true for the congenic endotoxin hyporesponsive C3H/HeJ strain. Therefore, C3H/HeJ mice are not defective in ganglioside metabolism per se but in the processing of an endotoxin stimulus such that one manifestation is an altered macrophage ganglioside pattern deficient in Gm1b.

The presence of sialidase-sensitive sialosylgangliotetraosyl ceramide (GM1b) in stimulated murine macrophages. Deficiency of GM1b in Escherichia coli-activated macrophages from the C3H/HeJ mouse

The stimulated murine macrophage was found to contain 11 major gangliosides of which 8 were determined to be monosialylated. The thin-layer chromatographic patterns were complicated by the presence of both sialic acid and ceramide fatty acid heterogeneity. N-glycolyl and N-acetylneuraminic acid-containing species were present for each ganglioside characterized. Although C18 sphingosine was the only long chain base detected, ceramide fatty acid ranged from C16 to C24 carbon moieties. Based on gas-liquid chromatographic and antibody analyses, all major tetraosyl structure gangliosides were ganglio series types. Comprising 43 to 60% of thioglycollate-stimulated cells and 60 to 70% of Escherichia coli-activated cells, monosialosyl-gangliotetraosyl ceromides (Gm1 gangliosides) were the major monosialo species of which four were present: sialidase-resistant NeuGc-GM1a and NeuAc-GM1a and sialidase sensitive NeuGc-GM1b and NeuAc-GM1b. Analyses of thioglycollate-elicited murine peritoneal macrophage ganglioside patterns from four strains of mice, including the C3H/HeJ strain, indicated that, in the absence of any expression of a genetic defect, the pattern is conserved. However, when E. coli was used as the activating agent, the normal C3H/HeN macrophage contained little Gm1a with the sialidase-sensitive Gm1b predominant; the converse was true for the congenic endotoxin hyporesponsive C3H/HeJ strain. Therefore, C3H/HeJ mice are not defective in ganglioside metabolism per se but in the processing of an endotoxin stimulus such that one manifestation is an altered macrophage ganglioside pattern deficient in Gm1b.

Tumor necrosis factor-alpha/cachectin enhances human immunodeficiency virus type 1 replication in primary macrophages

Macrophages are important target cells for human immunodeficiency virus type 1 (HIV-1). The ability of HIV-1 to productively infect macrophages may be influenced by endogenous cytokines that alter the activation state of these cells. In this study, the effect of tumor necrosis factor-alpha/cachectin (TNF alpha), a cytokine with macrophage-activating properties, on HIV-1 replication in primary blood monocyte-derived macrophages was examined. Treatment of macrophages with recombinant human TNF alpha (rTNF alpha), starting before or after HIV-1 infection, consistently enhanced viral production fivefold or greater above control (P less than .01). rTNF alpha was active at low concentrations (0.05-50 ng/ml) and increased the replication of both lymphocyte-tropic (human T lymphotropic virus type IIIB) and macrophage-tropic (human T lymphotropic virus type III BaL) strains of HIV-1. These findings provide additional evidence that TNF alpha may play a role in the pathogenesis of HIV-1 infection by upregulating viral expression in macrophages.

Altered B-lymphocyte membrane architecture indicated by ganglioside accessibility in C3H/HeJ mice

We have analyzed both the total ganglioside composition and the surface accessibility of C3H/HeN B lymphocytes and C3H/HeJ B lymphocytes. Seventeen individual resorcinol-positive moieties were visualized by two-dimensional thin-layer chromatography of the purified gangliosides from both strains. Complete homology between strains was seen in the patterns of total gangliosides purified from the endotoxin-responsive and -hyporesponsive strains, with only minor differences in the relative concentrations of four gangliosides. In comparison, only 12 individual gangliosides were accessible to surface labeling following galactose oxidase treatment in these same strains, suggesting that some gangliosides are masked at the cell surface in both strains. However, labeling of the more polar components was greatly reduced in the endotoxin-hyporesponsive (C3H/HeJ) strain, suggesting that these gangliosides have decreased accessibility to galactose oxidase at the cell surface. Therefore, while the total ganglioside compositions of the two strains were nearly equivalent, there were dramatic differences in ganglioside surface accessibility. These findings indicate that an alteration in membrane structure that is associated with the endotoxin hyporesponsiveness observed in C3H/HeJ B lymphocytes exists.

Altered in vivo activity of liposome-incorporated lipopolysaccharide and lipid A

We compared the abilities of free and liposome-incorporated Salmonella minnesota wild-type lipopolysaccharide (LPS) and lipid A to activate peritoneal macrophages and induce lethal toxicity in mice. Incorporation of lipid A into multilamellar vesicles resulted in a 100-fold-decreased potency to prime macrophages for phorbol myristate acetate-triggered release of H2O2. In addition, liposome incorporation reduced the lethality of LPS and lipid A at least 10-fold in dactinomycin-sensitized mice. Similar results were obtained with multilamellar liposomes delivered intravenously and when small unilamellar vesicles were employed. The observed difference in toxicity was not dependent on dactinomycin treatment, since a similar decrease was obtained with large doses of liposomal LPS in unsensitized mice. Control liposomes, prepared without LPS and lipid A, did not reduce the activities of the free compounds. The administration of a sublethal amount of liposomal LPS induced within 20 days, but not during the first week, tolerance to a subsequently injected lethal dose of free endotoxin. The latter observation suggests that early-phase tolerance is not the mechanism responsible for the reduced toxicity of liposomal LPS. These data show that liposomal LPS and lipid A have reduced endotoxic activity in vivo and are consistent with our hypothesis that a direct interaction of lipid A with appropriate plasma membrane components is necessary to efficiently trigger biologic responses. This interaction, however, is prevented by the stable insertion of LPS into the liposomal membrane.

Antimicrobial use in hospital-acquired infections

The appropriate use of antibiotics in nosocomial infections has been a goal of infectious disease practitioners and hospital epidemiologists since the emergence of resistant staphylococci more than 30 years ago. This challenge has assumed new proportions in the 1980s for many reasons. First, resistant gram-positive and gram-negative bacteria are increasingly common. Thus many traditional drugs or combinations of drugs lack efficacy. Second, there are so many new antibiotics available that it is difficult for any but the most knowledgeable to use each of them appropriately. Third, economic reality has forced hospitals and physicians to alter their activities and focus more on cost considerations than was ever necessary before. Last, infectious disease as a subspecialty in internal medicine is profoundly different in the 1980s; many infections must be controlled for life rather than cured because of underlying infection with human immunodeficiency virus, which suppresses immunity. The use of antibiotics is now rapidly changing and the state of the art in 1989 is likely to be outdated very soon as new pathogens emerge and new drugs are developed. The appropriate use of the quinolones is a great challenge that we now face. Can we preserve this valuable class of drugs, or will resistance develop quickly because of widespread, indiscriminate, and inappropriate use? To what extent can we phase out aminoglycoside use without compromising efficacy and without promoting the development of resistance? Do the monobactams have a real role to play in combination therapy? How should formularies approach the diverse cephalosporins that now inundate the market? These are only a few of the fundamental questions that must be addressed as this decade ends.

Treatment of experimental invasive aspergillosis with novel amphotericin B/cholesterol-sulfate complexes

An immunosuppressed rabbit model of invasive aspergillosis was used to evaluate a novel micellar preparation of cholesterol sulfate complexed to amphotericin B. The acute LD50 of amphotericin B-deoxycholate was 5.1 mg/kg versus 20 mg/kg for the amphotericin/cholesterol-sulfate complexes. Amphotericin B-deoxycholate given iv at a dose of 1.5 mg/kg was more effective in sterilizing liver and kidney than the amphotericin/cholesterol-sulfate complexes given iv at 1.5-4.5 mg/kg, but infection persisted in the lungs of all rabbits treated with those doses. Infection persisted even when the rabbits were given a lethal dose of amphotericin B-deoxycholate (4.5 mg/kg), but a dose of 15 mg/kg of the amphotericin/cholesterol-sulfate complexes sterilized tissues and was associated with no acute lethality. Equivalent doses of the amphotericin/cholesterol-sulfate complexes were less effective than amphotericin B-deoxycholate, but a fourfold decrease in acute lethality improved the therapeutic index of amphotericin B. The amphotericin/cholesterol-sulfate complexes appear to be an improved means of amphotericin B delivery and may improve therapy for invasive aspergillosis.

Factors mediating lipopolysaccharide-induced ganglioside expression in murine peritoneal macrophages

The ganglioside composition of endotoxin-responsive C3H/HeN murine peritoneal macrophages is known to undergo dramatic changes in vivo in response to intraperitoneal lipopolysaccharides (LPS), unlike endotoxin-hyporesponsive C3H/HeJ macrophages. To better investigate the mechanism behind LPS-induced macrophage ganglioside changes, resident C3H/HeN peritoneal macrophages were treated in vitro with 0.1-1.0 micrograms/ml LPS for 6-96 hr, but showed no differences in membrane ganglioside patterns. Coincubation of macrophages with lymphocytes and treating with LPS again elicited no ganglioside changes. In contrast, interferon gamma (IFN-gamma)-primed macrophages showed a dramatic shift in intensity of one ganglioside when treated with LPS in vitro; an additional macrophage ganglioside appeared when IFN-gamma-primed, LPS-treated macrophages were coincubated with lymphocytes. Ganglioside expression induced in vitro still did not approach the complex changes seen in vivo. However, transplanting C3H/HeN macrophages intraperitoneally into C3H/HeJ mice, followed by administration of intraperitoneal LPS, did reveal striking changes in ganglioside expression that resembled the pattern seen in vivo. Thus, LPS alone does not provide the necessary direct signal to promote macrophage ganglioside change even though it alters macrophage function. IFN-gamma appears to be one important mediator; however, complex interactions involving other cytokines or migration of independent populations of mononuclear cells may be required for the full manifestation of LPS-induced ganglioside expression in macrophages.

Incorporation of recombinant gamma interferon into liposomes enhances its ability to induce peritoneal macrophage antitoxoplasma activity

In this study we compared the ability of free- and liposome-incorporated murine recombinant gamma interferon (rIFN-gamma) to enhance peritoneal macrophage H2O2 release and antitoxoplasma activity in vitro. rIFN-gamma was efficiently (37 to 47%) incorporated into multilamellar vesicles composed of phosphatidylglycerol/cholesterol in a 2:1 molar ratio. The amount of rIFN-gamma incorporated into multilamellar vesicles and added to macrophages (0.1 to 1,000 U/ml) was quantitated with [3H]rIFN-gamma. The concentration of liposomal rIFN-gamma required to enhance macrophage H2O2 release (1 U/ml) and maximally inhibit Toxoplasma gondii growth (10 U/ml) was one-tenth the concentration required for free rIFN-gamma (10 and 100 U/ml, respectively). This increase in potency was observed in both thioglycolate-elicited and resident peritoneal macrophages. Control liposomes containing encapsulated buffer had no effect on the potency of free rIFN-gamma. The duration of macrophage activation induced by 24 h of liposomal rIFN-gamma treatment was also considerably longer than that induced by free rIFN-gamma (2 days versus less than 1 day). These data indicate that liposomal rIFN-gamma is more active than free rIFN-gamma as an inducer of macrophage microbicidal properties in vitro. This enhanced activity, combined with the potential for selective delivery of liposomal rIFN-gamma to phagocytic cells in vivo, may improve the therapeutic efficacy of rIFN-gamma in infections characterized by parasitization of phagocytes.

Comparison of thymocyte and T lymphocyte gangliosides from C3H/HeN and C3H/HeJ mice

Gangliosides have been prepared from resting murine thymocytes and splenic T cells. Profoundly different two-dimensional thin layer chromatography (2D TLC) patterns were observed between these two cell types. Thymocytes contained 28-30 discrete gangliosides of which eight represented major gangliosides. Splenic T lymphocytes from both strains had much simpler patterns, with six to seven major gangliosides and 12-13 minor gangliosides. Computerized analysis of the thymocyte ganglioside patterns between LPS-responder C3H/HeN mice and lipopolysaccharide (LPS)-hyporesponsive C3H/HeJ mice revealed no significant difference in the major gangliosides. However, with splenic T cell gangliosides, there is a striking difference in the relative proportion of three homologous gangliosides between the two strains. Consistent with previous observations on macrophage gangliosides, the ratio of N-acetylneuraminic acid-containing ganglioside to N-glycolylneuraminic acid-containing ganglioside was higher in both thymocytes and T-cells from the LPS-responder strain. These results show that sialic acid-containing glycolipids from thymocytes and T lymphocytes between endotoxin responder and hyporesponder strains manifest small but significant changes. These differences are present in unstimulated cell populations and may represent a manifestation of the Lps gene.

Activation of glomerular mesangial cells by gram-negative bacterial cell wall components

The cell walls of gram-negative bacteria contain several biologically active components, including lipopolysaccharide (LPS), lipoprotein, and protein 1. The effects of these individual components and a synthetic analog of lipoprotein, TPP, on several activation parameters of glomerular mesangial cells (MC) were examined. Prostaglandin secretion, synthesis of the autogrowth factor, mesangial interleukin-1 (IL-1), and new synthesis of cellular proteins were assessed as markers of MC activation. All bacterial cell wall components evaluated were active in varying degrees as stimulants of prostaglandin secretion. In general, PGE was the predominant product. TPP and protein 1 also induced substantial secretion of thromboxane. Each cell-wall component was effective in stimulating mesangial IL-1 secretion. The activation of MC was associated with the enhanced synthesis of many cellular proteins in addition to IL-1. Stimulation by these bacterial components was dependent on the state of the mesangial cell cycle, because nonproliferating cells did not respond to these factors. Activation of MC by gram-negative bacterial cell wall components, with release of vasoactive prostaglandins and peptide mitogens, may be responsible for some of the glomerular hemodynamic alterations and cellular proliferative events associated with sepsis or chronic bacterial infection.

A procedure for the efficient incorporation of wild-type lipopolysaccharide into liposomes for use in immunological studies

Previous studies on the mechanism of action of lipopolysaccharides (LPS) on macrophages have used wild-type lipopolysaccharide (wt-LPS) containing liposomes. In these studies the endotoxin was incorporated into liposomes by suspending the wt-LPS in the buffer used to rehydrate the lipid. Using this approach (buffer method), we observed that less than 10% of Salmonella minnesota smooth LPS is incorporated into multilamellar vesicles (MLV). If the non-incorporated material is not effectively separated from the liposomal form, erroneous conclusions on the mechanism of action of LPS can be drawn. Prolonged sonication of the wt-LPS-MLV suspension resulted in almost complete incorporation of the LPS into the resulting small unilamellar vesicles (SUV). In order to prepare MLV, we briefly soniated the buffer preparation, dehydrated the resulting smaller vesicles and then rehydrated the mixture (dry method). This procedure resulted in almost complete incorporation of the wt-LPS into MLV. The ability of wt-LPS in MLV prepared by the dry method to activate macrophages or trigger gelation of Limulus amoebocyte lysate was reduced by 100-1000-fold compared to the non-incorporated wt-LPS. This indicates that at least 99% of the wt-LPS is incorporated in MLV made by the dry method.

Acylation of monocyte and glomerular mesangial cell proteins. Myristyl acylation of the interleukin 1 precursors

Acylation of cellular proteins with the fatty acids myristate or palmitate represents an important mechanism for the co- or posttranslational modification of proteins. Lipid A, the biologically active component of bacterial endotoxin, exerts a number of biochemical effects on responsive cell types. Evidence is presented that lipid A stimulates the synthesis and subsequent myristyl acylation of intracellular monocyte and glomerular mesangial cell proteins. Two of the myristylated monocyte proteins were identified by specific immunoprecipitation as the 33-kD IL 1 alpha and beta precursors; a similar myristylated protein was found in mesangial cells. The 17-kD secretory form of monocyte IL 1 beta did not contain covalently linked myristate. Myristyl acylation of the IL 1 precursor proteins may facilitate the processing or membrane localization of these proteins, which lack characteristic hydrophobic signal sequences. The acylated 33-kD IL 1 alpha may remain preferentially associated with the membrane in an active form, whereas limited proteolysis may convert the biologically inactive IL 1 beta precursor into the extracellular, nonacylated, active 17-kD protein.

Effect of immunosuppression and amphotericin B on Aspergillus antigenemia in an experimental model

A modified enzyme-linked immunosorbent assay (ELISA) for crude carbohydrate antigen was used to evaluate the kinetics of aspergillus antigenemia and to determine the effect of therapy on circulating antigen levels in an experimental model. The ELISA was rapid, simple to perform, and able to detect less than 10 ng of antigen/mL of serum. The model was also used to evaluate the effect of temporary and persistent immunosuppression on experimental disease. Antigen levels rose progressively in untreated control rabbits; all 15 animals had significant antigenemia. Treated animals had markedly reduced antigen levels, but nine of 13 rabbits had detectable antigen after 72 h of therapy, a result that correlated with persistent disease. Therapy begun 24 h after challenge in temporarily immunosuppressed animals was more likely to sterilize tissues than was therapy begun 48 h after challenge. Therapy in persistently immunosuppressed rabbits was less effective and may require improved antifungal regimens to be successful.

The clinical value of gas-liquid chromatography in the detection of intra-amniotic microbial invasion

Short-chain organic acids are byproducts of bacterial metabolism, and their detection by gas-liquid chromatography (GLC) in amniotic fluid has been proposed as a rapid, sensitive, and specific method for the diagnosis of infection. This study was conducted to determine whether GLC analysis of amniotic fluid would be helpful in a population of women in whom the Gram stain examination was negative. Amniotic fluid was retrieved by transabdominal amniocentesis from three groups of patients. Group 1 (negative control) contained 14 women with term pregnancies without clinical and microbiologic evidence of infection of the amniotic cavity; group 2 (positive control) included 17 women with a positive Gram stain examination and culture of amniotic fluid; group 3 (study group) comprised 25 women at risk for intra-amniotic infection who had a negative Gram stain of amniotic fluid. None of the patients in group 1 and 16 of 17 patients (94.1%) in group 2 had pathologic short-chain organic acids in the amniotic fluid. Seven of the 25 patients in group 3 had a positive amniotic fluid culture and only two had an abnormal GLC pattern. Of the remaining 18 patients with negative amniotic fluid cultures, eight had abnormal GLC results. In group 3, the sensitivity of GLC was 28.5% and the specificity was 55.5%. Gas-liquid chromatographic analysis of amniotic fluid has limited clinical value in the prediction of amniotic fluid culture when the Gram stain examination is negative.

Incorporation of LPS in liposomes diminishes its ability to induce tumoricidal activity and tumor necrosis factor secretion in murine macrophages

We investigated the effect of lipopolysaccharide (LPS) incorporated into phospholipid vesicles (liposomes) on the induction of macrophage-mediated tumor cytotoxicity and tumor necrosis factor (TNF) secretion. The incorporation of Salmonella minnesota rough (Re)-LPS into multilamellar or small unilamellar vesicles (liposomes) resulted in an 100- to 1,000-fold reduction in its potency to activate both the macrophage cell line RAW 264.7 and murine thioglycolate elicited peritoneal macrophages to become cytotoxic for L929 and P815 tumor cells. Liposomal LPS was also a 100- to 1,000-fold less potent inducer of TNF secretion from RAW 264.7 cells. Cytokines secreted by the activated macrophages contributed to the cytotoxic effect on the L929 cells but not the P815 cell line. Human recombinant TNF was not cytotoxic for either cell line but was cytostatic for the L929 cell line. Morphological examination of the cells after uptake of fluorescent, free, and liposomal LPS revealed that both forms were internalized by the endocytic pathway. This, together with the considerably reduced potency of liposomal LPS to induce tumor cytotoxicity and TNF secretion, suggests that the interaction of the hydrophobic part of the lipid A moiety of LPS with the macrophage plasma membrane is needed to optimally activate these cells. Incorporation of LPS into liposomes effectively abrogates this interaction.

Oral ciprofloxacin in resistant urinary tract infections

Thirty-two patients (18 men and 14 women), who ranged in age from 28 to 91 years (mean, 71.2 years), with urinary tract infections caused by Pseudomonas species or other organisms resistant to trimethoprim-sulfamethoxazole were treated with 500 mg of orally administered ciprofloxacin every 12 hours. Thirty patients completed at least five days of therapy and were evaluated for efficacy. Of these, the treatment of 28 (93 percent) patients was considered successful, with urine cultures yielding negative results five to nine days after cessation of therapy. Three of these patients were found to be reinfected with their primary pathogens when culture specimens were obtained again three to four weeks later. The two patients who received treatment that was classified as having failed had urine cultures that persistently grew Pseudomonas aeruginosa. Superinfections occurred in eight patients, four with diabetes and four with underlying central nervous system disease. Adverse reactions required discontinuation of therapy in two patients. Although the rates of reinfection and superinfection were somewhat high, these patients had a high frequency of underlying diseases that predisposed them to recurrent or difficult-to-treat infections. Despite these shortcomings, ciprofloxacin is a welcome addition to the oral antibiotic regimen for the treatment of antibiotic-resistant urinary infections.

Modulation of the biological activity of bacterial endotoxin by incorporation into liposomes

In an attempt to define the mechanism by which endotoxin induces its biological activity, we studied the effect of the incorporation of lipopolysaccharide and lipid A into phospholipid vesicles (liposomes) on the stimulation of the macrophage cell-line RAW 264.7 and on the coagulation of Limulus amoebocyte lysate. The incorporation of Salmonella minnesota smooth-and rough (Re) lipopolysaccharide or primarily monophosphoryl lipid A into multilamellar and small unilamellar vesicles consisting of phosphatidylcholine, phosphatidylserine and cholesterol (molar ratio 4:1:4) reduced the interleukin 1 inducing potency of these substances about 1000-fold. When corrected for the actual uptake of radiolabeled free and liposome-incorporated lipopolysaccharide by the cells, this difference amounted to 100- to 1000-fold. In addition, liposome-associated Re-lipopolysaccharide was about 1000-fold less potent in stimulating the Fc-receptor mediated uptake of IgG-coated sheep erythrocytes by the cells. The ability of lipopolysaccharide and lipid A to coagulate the Limulus amoebocyte lysate appeared to be at least 100-fold decreased upon incorporation into phospholipid vesicles. Control experiments demonstrated that liposomes prepared without lipopolysaccharide did not reduce the studied activities of free lipopolysaccharide. In conclusion, the incorporation of lipopolysaccharide into the liposomal membrane probably prevents the interaction of the hydrophobic portion of the lipid A component of lipopolysaccharide with the plasma-membrane structures involved in the activation of macrophages and with the proteins of the Limulus amoebocyte lysate. This indicates that the direct interaction of the lipid A moiety of lipopolysaccharide with the macrophage plasma-membrane is required to optimally trigger the studied responses.

Modulation of the biological activity of bacterial endotoxin by incorporation into liposomes

In an attempt to define the mechanism by which endotoxin induces its biological activity, we studied the effect of the incorporation of lipopolysaccharide and lipid A into phospholipid vesicles (liposomes) on the stimulation of the macrophage cell-line RAW 264.7 and on the coagulation of Limulus amoebocyte lysate. The incorporation of Salmonella minnesota smooth-and rough (Re) lipopolysaccharide or primarily monophosphoryl lipid A into multilamellar and small unilamellar vesicles consisting of phosphatidylcholine, phosphatidylserine and cholesterol (molar ratio 4:1:4) reduced the interleukin 1 inducing potency of these substances about 1000-fold. When corrected for the actual uptake of radiolabeled free and liposome-incorporated lipopolysaccharide by the cells, this difference amounted to 100- to 1000-fold. In addition, liposome-associated Re-lipopolysaccharide was about 1000-fold less potent in stimulating the Fc-receptor mediated uptake of IgG-coated sheep erythrocytes by the cells. The ability of lipopolysaccharide and lipid A to coagulate the Limulus amoebocyte lysate appeared to be at least 100-fold decreased upon incorporation into phospholipid vesicles. Control experiments demonstrated that liposomes prepared without lipopolysaccharide did not reduce the studied activities of free lipopolysaccharide. In conclusion, the incorporation of lipopolysaccharide into the liposomal membrane probably prevents the interaction of the hydrophobic portion of the lipid A component of lipopolysaccharide with the plasma-membrane structures involved in the activation of macrophages and with the proteins of the Limulus amoebocyte lysate. This indicates that the direct interaction of the lipid A moiety of lipopolysaccharide with the macrophage plasma-membrane is required to optimally trigger the studied responses.

Endotoxins and disease mechanisms

In this chapter, current concepts about the mechanisms of action of endotoxin are reviewed. Particular attention is focused upon endotoxin-induced production of soluble mediators from macrophages and mononuclear cells and on the potential contribution of these mediators to endotoxin shock. In many cases, the interrelationships between these mediators as primary and/or secondary consequences of endotoxin stimulation of mononuclear phagocytes are discussed. Final comments address the relevance of these mediators to the therapy of endotoxin shock.

Ganglioside expression in macrophages from endotoxin responder and nonresponder mice

Peritoneal macrophage ganglioside patterns and ganglioside sialic acid content were compared for two congenic strains of mice having differing responses to bacterial lipopolysaccharide. Resident macrophage ganglioside patterns from C3H/HeJ mice (endotoxin hyporesponsive) and C3H/HeN mice (endotoxin responsive) were similar. Macrophages elicited with phenol-extracted or butanol-extracted endotoxin showed distinctly more complex ganglioside patterns in C3H/HeN mice. C3H/HeJ macrophages showed distinct, but less complex changes when elicited with butanol-extracted endotoxin. As expected, there were minimal alterations induced by phenol-extracted endotoxin in the C3H/HeJ patterns. When injected with whole killed E. coli, both strains of mice exhibited complex ganglioside patterns; however, there were relative differences in the quantities of multiple gangliosides. Differences in ganglioside patterns were mirrored in the relative ratios of N-acetyl- to N-glycolylneuraminic acid. When macrophages were activated by administration of either endotoxin preparation, macrophage gangliosides from C3H/HeN mice always contained a higher proportion of N-acetylneuraminic acid compared with C3H/HeJ macrophage gangliosides. Oxidative metabolism of the macrophage populations was assessed by PMA-induced H2O2 release. This indicated that endotoxin activation produced an increase in PMA-induced H2O2 release as well as a shift of sialic acid class from the N-glycolyl type to the N-acetyl type. However, no direct correlation could be made between ganglioside composition, sialic acid content, and macrophage function. These data indicate that both ganglioside composition and sialic acid composition of macrophages are profoundly altered with endotoxin activation. The data further indicate that under conditions which C3H/HeJ mice respond to Gram-negative bacteria, their macrophage ganglioside patterns still differ from normal mice.

Ganglioside expression in macrophages from endotoxin responder and nonresponder mice

Peritoneal macrophage ganglioside patterns and ganglioside sialic acid content were compared for two congenic strains of mice having differing responses to bacterial lipopolysaccharide. Resident macrophage ganglioside patterns from C3H/HeJ mice (endotoxin hyporesponsive) and C3H/HeN mice (endotoxin responsive) were similar. Macrophages elicited with phenol-extracted or butanol-extracted endotoxin showed distinctly more complex ganglioside patterns in C3H/HeN mice. C3H/HeJ macrophages showed distinct, but less complex changes when elicited with butanol-extracted endotoxin. As expected, there were minimal alterations induced by phenol-extracted endotoxin in the C3H/HeJ patterns. When injected with whole killed E. coli, both strains of mice exhibited complex ganglioside patterns; however, there were relative differences in the quantities of multiple gangliosides. Differences in ganglioside patterns were mirrored in the relative ratios of N-acetyl- to N-glycolylneuraminic acid. When macrophages were activated by administration of either endotoxin preparation, macrophage gangliosides from C3H/HeN mice always contained a higher proportion of N-acetylneuraminic acid compared with C3H/HeJ macrophage gangliosides. Oxidative metabolism of the macrophage populations was assessed by PMA-induced H2O2 release. This indicated that endotoxin activation produced an increase in PMA-induced H2O2 release as well as a shift of sialic acid class from the N-glycolyl type to the N-acetyl type. However, no direct correlation could be made between ganglioside composition, sialic acid content, and macrophage function. These data indicate that both ganglioside composition and sialic acid composition of macrophages are profoundly altered with endotoxin activation. The data further indicate that under conditions which C3H/HeJ mice respond to Gram-negative bacteria, their macrophage ganglioside patterns still differ from normal mice.

Modulation of murine macrophage metabolism by glycolipids: inhibition of LPS-induced metabolism by specific gangliosides

We have investigated the ability of gangliosides isolated from murine brain to modulate macrophage metabolism. LPS elicits a profound increase in glucose consumption by cultured resident macrophages. When highly purified mouse brain gangliosides are added to macrophage cultures, a modest inhibition of baseline glucose utilization occurs. Both disialogangliosides and trisialogangliosides mediate this effect. In the absence of serum, these gangliosides may be toxic to cultured macrophages. GT1b is the only brain ganglioside tested that specifically inhibited LPS-induced macrophage metabolism. Sialic acid appears to be a necessary component of the gangliosides, although it is not sufficient to induce inhibition. Asialoganglioside and free sialic acid have no effect on macrophage metabolism in comparison with intact gangliosides. The inhibition of LPS-induced metabolism may be explained by the ability of LPS to form stable molecular complexes with both disialogangliosides and trisialogangliosides. These experiments also suggest that the ganglioside content of macrophages may influence functional responses of macrophages to exogenous stimuli.

Gangliosides block the inhibition of macrophage Fc-dependent phagocytosis by lipopolysaccharide

The mechanism whereby bacterial lipopolysaccharide (LPS) exerts its biologic effects on mammalian cells is unknown. Plasma membrane gangliosides bind bacterial toxins and have been implicated in modulating the effects of a variety of immunoregulatory substances. We investigated the possibility that gangliosides can inhibit the effect of lipopolysaccharide on Fc-dependent phagocytosis by murine peritoneal macrophages. Protein-free lipopolysaccharide preparations significantly inhibited Fc-mediated phagocytosis (less than 71% of control) at concentrations of 100 ng/ml or greater after 90 min of incubation. The inhibitory effect of LPS (1 micrograms/ml) was blocked when macrophages were incubated with mono-, di-, or trisialogangliosides (25-50 micrograms/ml). Neither asialoganglioside nor sialic acid alone were capable of blocking the effect of LPS. When chromatographed separately on a Sepharose 4B column, LPS and trisialoganglioside had different elution profiles. LPS and trisialoganglioside coeluted, however, when premixed at 37 degrees C for 60 min and then applied to the column. Therefore, abrogation of the effect of LPS on Fc-dependent phagocytosis may occur as a consequence of direct interaction between LPS and gangliosides. These data suggest that gangliosides may modulate the response of macrophages to bacterial lipopolysaccharide.

Interleukin 1 and the glomerular mesangium. I. Purification and characterization of a mesangial cell-derived autogrowth factor

The proteins expressing interleukin 1 (IL 1) activity from rat peritoneal macrophages and cultured glomerular mesangial cells were compared after purification to apparent homogeneity. The purified IL 1 shared a number of biochemical features including m.w., charge, and specific activity. These findings were extended by the results of proteolytic peptide mapping, which revealed similar breakdown oligopeptides, confirming the close resemblance of these two IL 1 species produced by macrophages and mesangial cells. The purified mesangial cell IL 1 acts as an autocrine or paracrine growth factor. The local release of this cytokine may be an important factor in glomerular diseases characterized by mesangial proliferation and matrix expansion.

Interleukin 1 and the glomerular mesangium. I. Purification and characterization of a mesangial cell-derived autogrowth factor

The proteins expressing interleukin 1 (IL 1) activity from rat peritoneal macrophages and cultured glomerular mesangial cells were compared after purification to apparent homogeneity. The purified IL 1 shared a number of biochemical features including m.w., charge, and specific activity. These findings were extended by the results of proteolytic peptide mapping, which revealed similar breakdown oligopeptides, confirming the close resemblance of these two IL 1 species produced by macrophages and mesangial cells. The purified mesangial cell IL 1 acts as an autocrine or paracrine growth factor. The local release of this cytokine may be an important factor in glomerular diseases characterized by mesangial proliferation and matrix expansion.

Synergism of azlocillin, mezlocillin, piperacillin in combination with tobramycin against Klebsiella and Pseudomonas

Fifty-three clinical isolates of Klebsiella and fifty-one clinical isolates of Pseudomonas aeruginosa, twenty-six of which were carbenicillin-(CARB) resistant, were tested for susceptibility to mezlocillin (MEZ), azlocillin (AZL), and piperacillin (PIP), both alone and in combination with tobramycin (TOB) using the microtiter broth diluent method and an inoculum density of 10(6) CFU/ml. The Klebsiella were highly resistant to TOB, MEZ, and PIP (MIC90: 8, greater than 256, greater than 128 micrograms/ml, respectively). Synergy was demonstrated in 53 percent (PIP/TOB) and 51 percent (MEZ/TOB). An indifferent response was observed in 47 percent (PIP/TOB) and 49 percent MEZ/TOB of the Klebsiella. PIP, MEZ, and AZL in combination with TOB showed synergism against CARB-resistant Pseudomonas in less than 10 percent of the strains tested. Synergy could be demonstrated against CARB-susceptible Pseudomonas with the combinations PIP/TOB, AZL/TOB, and MEZ/TOB in 12 percent, 12 percent, and 24 percent, respectively, of the twenty-five strains tested. Indifferent effects were observed in 84 percent, 88 percent, and 76 percent, respectively, of these same CARB-susceptible strains. These data suggest that there is no significant difference in the incidence of synergy with these new penicillins and tobramycin against either Pseudomonas or Klebsiella.

Ganglioside modulation of lipopolysaccharide-initiated complement activation

Highly purified preparations of mouse gangliosides have been demonstrated to bind to purified preparations of lipopolysaccharide (LPS). In some instances, the binding has been demonstrated to be dependent upon the presence of sialic acid in the ganglioside preparation. The binding of gangliosides to LPS from the deep rough Salmonella minnesota Re mutant has suggested that the interaction involves the lipid A-2-keto-3-deoxyoctulosanate region of the LPS macromolecule. The interaction between gangliosides and LPS has been demonstrated to result in an abrogation of lipid A dependent activation of the classical pathway of serum complement by Re LPS. Surprisingly, however, the presence of sialic acid containing glycolipids has been shown to enhance significantly the capacity of LPS to initiate activation of the alternative pathway of complement. These data suggest that sialic acid can enhance as well as inhibit the formation of a stable alternative-pathway C3 convertase.

Gangliosides reduce leakage of aqueous-space markers from liposomes in the presence of human plasma

We have studied the role of glycolipids in reducing leakage of aqueous-space markers from liposomes, composed primarily of egg phosphatidylcholine, in the presence of human plasma. Liposomes were either small unilamellar (SUV) or large unilamellar (LUV). Leakage of liposome contents as affected by the incorporation into the liposomal bilayer of mono-, di-, or trisialogangliosides (GM, GD, GT) at different molar ratios in the presence or absence of cholesterol was examined. Leakage from liposomes decreased with increasing ganglioside sialic acid. Asialogangliosides had no effect on calcein leakage in the presence of plasma. The stabilizing effect of gangliosides and cholesterol was synergistic, and SUV containing 10 mol% GT and 33 mol% cholesterol had a half-life for leakage of calcein in plasma at 37 degrees C approaching 24 hours. LUV in the presence of plasma retained their contents longer than SUV, and gangliosides had an additional stabilizing effect. Phosphatidylserine and sulfatides were also capable of substituting for gangliosides in stabilizing liposomes to plasma-induced leakage. It appears that gangliosides stabilize liposomes in plasma at least in part through their ability to impart surface negative charge.

Ganglioside alterations in stimulated murine macrophages

A two-dimensional thin-layer chromatographic technique has been used to separate and display gangliosides from murine peritoneal macrophages in different functional states. Resident macrophages have a relatively simple ganglioside pattern with about 15 resorcinol-positive spots. Gangliosides from resident cells contained mostly (90%) N-glycolylneuraminic acid. Thioglycolate-elicited and Corynebacterium parvum-activated macrophages have much more complex patterns with about 40 resorcinol-positive spots. Although ganglioside sialic acid content of stimulated macrophages was only slightly higher than that of resident cells, it consisted of nearly equal amounts of N-acetyl- and N-glycolylneuraminic acid. The shift in the ganglioside sialic acid type and the expression of different gangliosides in macrophages upon stimulation may help explain some of the differences in function and responsiveness noted in these macrophage populations.