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Biomedical subjects

J S Solomkin

Publications and source records attributed to J S Solomkin.

At least 55 records · Page 3Linked to original sources
PubMed1990

Neutrophil disorders in burn injury: complement, cytokines, and organ injury.

Because of the association of burn injury with subsequent bacterial infection, numerous studies have been performed characterizing neutrophil function in burn injury. These studies provide a picture of intravascular complement activation, neutrophil-C5a interactions, and consequent disordered cellular function. Neutrophil dysfunction includes suppressed random and C5a-directed migration and hyperresponsiveness to oxidative stimuli. These observations do not explain the histologic and functional involvement of neutrophils in ARDS and perhaps other organ failure states. Circumstantial and extrapolated information suggests that macrophage-lineage cells function as regulators of neutrophil function within matrix environments in burn injury. Elevated endotoxin levels have been found in burned patients, which would support the notion of endotoxin-stimulated monocytes/macrophages as inducing neutrophil migration into connective tissue matrices (LTB4 and IL-8), inducing prolonged oxidant production (TNF-alpha, GM-CSF), and inducing neutrophil release of regulatory substances from neutrophils (G-CSF). This information suggests a variety of experimental approaches to testing this hypothesis.

Burns↗
PubMed1989

Production and release of C3 by cultured monocytes/macrophages isolated from burned, trauma, and septic patients.

The release of C3 under various conditions by cultured monocytes/macrophages isolated from burned, trauma, and septic trauma patients was determined. When monocytes were cultured for up to 14 days there was no difference in production and release of C3 by normals and patients; C3 production rose slowly at first then rose rapidly from 8-14 days of culture. C3 production continued for up to 28 days of culture. When lymphocytes were present with the monocytes for the first 24 hr of culture there were differences in C3 production by normal and patient cells at various times of culture. There were differences in C3 release by patients' 24 hour-cultured cells at certain postburn and injury days. Macrophages from burned patients released less C3 than normal cells and macrophages from septic trauma patients released more C3 than normal cells.

Burns↗
PubMed1988

Characterization of N-formyl-methionyl-leucyl-phenylalanine receptors on human neutrophils. Effects of isolation and temperature on receptor expression and functional activity.

The study of polymorphonuclear neutrophil (PMN) surface receptor expression provides a means for the assessment of PMN function and state of cellular activation. In this study, we characterized binding of the chemotactic peptide FMLP to whole PMN, with particular attention to those variables that may account for the wide variation reported in the literature. These included avoidance of oxidized FMLP as a radioligand contaminant, determination of the optimal cold ligand concentration necessary for achieving minimal nonspecific binding throughout the range of radioligand concentrations used in saturation experiments (greater than or equal to 5 x 10(-5) M), avoidance of radioligand concentrations that equal or exceed receptor saturation and are not suitable for Scatchard analysis (greater than or equal to 60 to 80 nM), and avoidance of inadvertent receptor mobilization due to room temperature PMN isolation techniques and cell warming. PMN isolated and maintained at 4 degrees C expressed a single, high affinity population of FMLP receptors (approximately 6000 receptors per cell) with a KD of 15.5 nM. These characteristics, and in particular the single-affinity nature of the expressed FMLP receptor site, were derived from saturation experiments and confirmed with agonist competition studies. PMN subjected to room temperature isolation or 37 degrees C warming exhibited a 2.5-fold increase in FMLP receptor expression (approximately 15,000 receptors per cell) without changes in receptor affinity. These latter PMN, in correlation with increased receptor expression, had increased initial, maximal rates of FMLP-induced superoxide generation (10.2 vs 6.3 nmol/min/10(6) PMN for cells isolated and maintained at 4 degrees C) as a manifestation of their functional activation. The avoidance of inadvertent cellular activation during PMN isolation is essential to studies of PMN function, activation and the role of FMLP receptor expression/mobilization in these processes.

Binding, Competitive↗
PubMed1988

Neutrophil activation in sepsis. The relationship between fmet-leu-phe receptor mobilization and oxidative activity.

To elucidate further the manifestations and mechanisms of neutrophil (PMN) activation, PMNs from control and septic subjects were studied at baseline and under conditions of graded, in vitro activation. At baseline (4 degrees C PMN isolation), septic-derived PMNs were activated, as manifested by twofold increases in fmet-leu-phe (FMLP)-induced oxidative activity and concomitant FMLP surface receptor expression, compared with controls. Following degranulationlike maximal activation (phorbol myristate acetate pretreatment), both PMN populations exhibited maximal FMLP-induced oxidative priming and receptor up-regulation. However, following exudation-like moderate activation (37 degrees C pretreatment), control PMNs underwent significant receptor mobilization and oxidative priming but septic-derived PMNs exhibited oxidative deactivation (decreased FMLP-induced oxidative activity) without changes in FMLP receptor expression. Our data support the theory that while circulating PMNs in sepsis may promote oxidant-related microvascular lung injury, their oxidative deactivation following transpulmonary exudation (simulated by 37 degrees C pretreatment) may underlie the increased incidence of pulmonary infections seen in sepsis-induced adult respiratory distress syndrome.

Bacterial Infections↗
PubMed1988

Use of new beta-lactam antibiotics for surgical infections.

The availability of beta-lactam antibiotics with extended spectra of activity against organisms commonly seen in surgical infections suggests that aminoglycoside-based therapy is no longer needed for most such community-acquired infections. The primary problems with specific beta-lactams are lack of activity against Bacteroides species and variable activity against Pseudomonas aeruginosa and enterococci. The pharmacokinetic properties of the newer beta-lactams vary considerably. This variation suggests specific settings in which these properties may be taken advantage of to improve clinical outcome.

Anti-Bacterial Agents↗
PubMed1987

Complement-mediated neutrophil activation in sepsis- and trauma-related adult respiratory distress syndrome. Clarification with radioaerosol lung scans.

Complement-mediated neutrophil activation (CMNA) has been proposed as an important pathogenic mechanism causing acute microvascular lung injury in the adult respiratory distress syndrome (ARDS). To clarify the relationship between CMNA and evolving lung injury, we studied 26 patients with multiple trauma and sepsis within 24 hours of risk establishment for ARDS. Pulmonary alveolar-capillary permeability (PACP) was quantified as the clearance rate of a particulate radioaerosol. Seventeen patients (65%) had increased PACP (six developed ARDS) while nine (35%) had normal PACP (none developed ARDS; clearance rates of 3.4%/min and 1.5%/min, respectively). These patients, regardless of evidence of early lung injury, had elevated plasma C3adesArg levels and neutrophil chemotactic desensitization to C5a/C5adesArg. Plasma C3adesArg levels correlated weakly, but significantly, with PACP. Thus, CMNA may be a necessary, but not a sufficient, pathogenic mechanism in the evolution of ARDS.

Adult↗
PubMed1987

Design and conduct of antibiotic trials. A report of the Scientific Studies Committee of the Surgical Infection Society.

Several recent publications have identified important methodologic problems in the design and conduct of antimicrobial trials in surgery. Developed by consensus of the members of the Scientific Studies Committee of the Surgical Infection Society, this report provides broad guidelines for the construction of antimicrobial trials. The central issues identified include pretrial definition of study purpose, entry criteria, assignment device, and statistical analysis. These issues are fundamental in designing studies with an acceptable likelihood of finding differences among those antimicrobial regimens at least risk to the study subjects. The importance of stratifying patients on the basis of background condition, disease, and severity of illness is stressed. The inclusion in a study of variables that enhance the statistical power and, therefore, the believability of this study is stressed as an important means of clarifying substantial differences between therapies.

Abdomen↗
PubMed1987

Surface receptor mobilization in complement-mediated neutrophil activation: characterization and effects of methylprednisolone.

Complement-mediated neutrophil activation (CMNA) is an important host defense mechanism that is essential for effective neutrophil (PMN) proinflammatory activity. It has also been implicated as a pathogenic mechanism contributing toward the development of adult respiratory distress syndrome. Utilizing zymosan-activated serum pretreatment as an in vitro model for CMNA, we characterized the effects of CMNA on PMN superoxide (SO) production and N-formyl-methionyl-leucyl-phenylalanine (FMLP) receptor status. CMNA was associated with a 132 +/- 38% increase in FMLP-induced SO generation and a 110 +/- 30% increase in FMLP receptor expression. Methylprednisolone pretreatment prevented both the FMLP receptor mobilization and the SO priming effects of CMNA. These data support a concept that FMLP receptor mobilization is an important element in the PMN activation process. In addition, blocking this phenomenon may have clinical significance in attempts to modulate the potential damaging effects of the increased PMN oxidative metabolism associated with CMNA.

Complement System Proteins↗
PubMed1987

Increased pulmonary alveolar-capillary permeability in patients at risk for adult respiratory distress syndrome.

Two methods for predicting adult respiratory distress syndrome (ARDS) were evaluated prospectively in a group of 81 multitrauma and sepsis patients considered at clinical high risk. A popular ARDS risk-scoring method, employing discriminant analysis equations (weighted risk criteria and oxygenation characteristics), yielded a predictive accuracy of 59% and a false-negative rate of 22%. Pulmonary alveolar-capillary permeability (PACP) was determined with a radioaerosol lung-scan technique in 23 of these 81 patients, representing a statistically similar subgroup. Lung scanning achieved a predictive accuracy of 71% (after excluding patients with unilateral pulmonary contusion) and gave no false-negatives. We propose a combination of clinical risk identification and functional determination of PACP to assess a patient's risk of developing ARDS.

Adult↗
PubMed1987

A review of antibiotic prophylaxis for open fractures.

A review of the literature strongly supports the use of antibiotic prophylaxis in open fracture management. Because of their broad spectrum of activity, cephalosporins are the drugs of choice in cases of orthopaedic trauma. The extent of the injury determines the appropriate agent and the length of time it should be given. Patients with Type 1 or Type 2 fractures require only brief treatment (one preoperative and two postoperative doses) with an agent that has good antistaphylococci activity. Cephalothin, cefazolin, cefamandole or cefuroxime are recommended. Type 3 fractures present a much greater problem because of the risk of gram-negative infection. The marked activity of cefuroxime, cefamandole, and cefotaxime against these organisms recommends their use in such cases. Combination regimens with aminoglycosides require further study to define added efficacy and to define appropriate dosing regimens. We advocate that antibiotic prophylaxis should be given as soon as possible to all patients with open fractures and Type 3 fractures, and that prophylaxis should continue until 48 hours after adequate soft tissue coverage is achieved.

Anti-Bacterial Agents↗
PubMed1986

Degranulation inhibition. A potential mechanism for control of neutrophil superoxide production in sepsis.

Previous studies with neutrophils from patients with intra-abdominal sepsis have provided convincing evidence of in vivo exposure to C5a. However, in contradistinction to normal cells pretreated with C5a, patient cells showed depressed superoxide response to N-formyl-methionyl-leucyl-phenyl-alanine (FMLP) and enhanced FMLP receptor affinity. To identify possible mechanisms responsible for these findings, we examined the effects of lysosomal alkalinization with the weak base clindamycin on normal neutrophils with and without C5a. Our results showed a specific suppression of FMLP-induced superoxide production and a loss of low-affinity FMLP receptors. These results occurred in the presence of clindamycin levels that did not interfere with other cellular processes. These findings suggest that regulation of neutrophil function during the course of intra-abdominal sepsis may be due to effectors active both at the cell surface (C5a) and within the lysosome. The clinical significance of our findings relates to a possible mechanism for specific pharmacologic suppression of oxide-radical production by neutrophils. Such oxide radicals are believed to be important in the capillary injury accompanying severe sepsis.

Blood Proteins↗
PubMed1986

Ceftazidime versus tobramycin plus ticarcillin in the treatment of soft-tissue infections.

Case report forms from a multicenter, randomized trial comparing ceftazidime (50 patients) with tobramycin plus ticarcillin (control group, 44 patients) in the treatment of skin and soft-tissue infections were reviewed. Two subsets of patients were identified. The target patient population (group I) comprised older patients with predisposing chronic disease (eg, diabetes mellitus) and an average of 1.8 bacterial pathogens per patient. Necrotizing soft-tissue and postoperative wound infections predominated. Group II comprised younger patients with acute onset of monomicrobial cellulitis or staphylococcal or streptococcal abscess. Clinical cure or improvement was achieved in 93% of ceftazidime-treated and 94% of control group I patients. Bacteriological eradication of the initial pathogens without superinfection was obtained in 85% and 82%, respectively, of the two treatment groups. In group II, each of the nine ceftazidime-treated patients was cured or improved and bacteria were eradicated; in the control group, nine of ten patients were clinically and bacteriologically cured. Among all patients, Staphylococcus aureus was eradicated in 18 of 19 treated with ceftazidime and in 14 of 15 treated with the control agents. The results of the study demonstrate the efficacy of ceftazidime as initial monotherapy for soft-tissue infections in patients with compromised vascularity.

Abscess↗
PubMed1986

A rapid method for monocyte isolation and chemotaxis.

A rapid method for isolating human peripheral blood monocytes and studying chemotaxis is described. The cells are isolated at a mean purity of 60% (+/- 10%) using Dextran. T500 sedimentation of whole blood, followed by centrifugation of the leucocyte-rich plasma obtained on a discontinuous Percoll gradient (density 1.067 g/ml). Chemotaxis was performed using a 48-well chamber and the chemoattractants activated serum (C5a) and FMLP and was proven by checkerboard analysis. Using this technique pooled serum was found to be activated by the PVP-coated polycarbonate filter in use, producing the attractant C5a. At high concentrations this produced a chemotactic response identical to zymosan-activated serum (ZAS). This technique requires small volumes of blood (15 ml) and enables monocyte isolation and chemotaxis to be completed in approximately 4 hr using leucocyte preparations in which the monocyte is the predominant cell. It therefore facilitates the sequential investigation of monocyte function in patients.

Cell Separation↗
PubMed1986

Monocyte dysfunction in severe trauma: evidence for the role of C5a in deactivation.

Consecutive severely traumatized patients (n = 16) requiring intensive care underwent serial monitoring of complement activation and monocyte migratory function with the chemoattractant activated serum (C5a) and formyl-methionyl-leucyl-phenylalanine (FMLP). Complement was found to be activated, and chemotaxis to C5a was correspondingly depressed maximally at a mean 5 to 7 days after injury (p = less than 0.01). The migratory response to FMLP was within the normal range throughout. Conversely, in a consecutive series of patients undergoing aortoiliac bypass grafting (n = 11), there was no evidence of complement activation, and monocyte migratory function remained normal for both C5a and FMLP. These data suggest that in patients with severe trauma, the activation of complement, particularly the fifth component (C5a), reduces the migratory responsiveness of circulating monocytes to C5a. This reduction in a host-response mechanism may explain the propensity to infection and poor wound healing seen in patients with severe trauma and also indicates that C5a, thought to be the major in vivo chemoattractant for leukocytes, has profound systemic actions.

Adult↗
PubMed1986

The effects of methylprednisolone on complement-mediated neutrophil activation during cardiopulmonary bypass.

Complement-mediated neutrophil activation (CMNA) has been implicated as an important pathophysiologic mechanism contributing to acute microvascular lung injury in the adult respiratory distress syndrome (ARDS). Using cardiopulmonary bypass (CPB) as a clinical model for complement-mediated microvascular injury, we studied the effects of methylprednisolone (MPSS) pretreatment on manifestations of CMNA in 28 pediatric patients undergoing CPB. Six patients not receiving MPSS served as controls. Results demonstrated that MPSS did not prevent complement activation as noted by 4.5- and 7.7-fold increases in plasma C3a des Arg levels during and immediately after CPB, respectively. However, detectable in vivo and in vitro manifestations of CMNA were altered. Neutropenia during CPB was attenuated to 65% of prebypass values compared with 47% in the control group. Neutrophil selective chemotactic desensitization toward C5a/C5a des Arg during the on bypass and postbypass periods was evident in the control group (0.41 and 0.76 cm specific migration, respectively) and prevented in the MPSS group (1.55 and 2.00 cm specific migration, respectively). We conclude that CMNA during CPB is ameliorated and/or prevented by MPSS pretreatment. These findings suggest that MPSS pretreatment may ameliorate complement-mediated microvascular (lung) injury in CPB and ARDS.

Anaphylatoxins↗
PubMed1985

Randomized trial of imipenem/cilastatin versus gentamicin and clindamycin in mixed flora infections.

Results of a randomized trial comparing imipenem/cilastatin versus the combination of gentamicin plus clindamycin for mixed flora surgical sepsis are reported herein. Seventy-four patients were evaluable, 50 of whom had intra-abdominal sepsis. No imipenem-resistant initially infecting isolates were encountered. When outcome was evaluated on the basis of severity scoring (APACHE II), no difference in mortality was noted. However, therapy in two patients with Pseudomonas emerging from a polymicrobial flora failed with gentamicin, whereas no Pseudomonas failures were noted with imipenem/cilastatin. The major difference noted was in toxicity. There was a 20 percent incidence of nephrotoxicity in gentamicin-treated patients despite serum level monitoring and multiple dose adjustments. The degree of efficacy and the relative tolerability of imipenem/cilastatin in seriously ill surgical patients is demonstrated.

Adult↗