Pleurodesis by autologous blood, doxycycline, and talc in a rabbit model.

BACKGROUND: Management of recurrent spontaneous pneumothorax or symptomatic pleural effusion often uses thoracoscopic pleurodesis, about which many questions remain. Both effectiveness and toxicity of agents currently used for pleurodesis were evaluated in a rabbit model. METHODS: Agents administered were autologous blood 1 mL/kg, talc slurry (70 mg x mL(-1) x kg(-1)), and doxycycline 10 mg/mL, given through a chest tube to 30 rabbits. Controls had only chest tubes inserted. At 30 days surfaces were graded by gross observation and histologic examination. Blood and lung tissue from all animals were analyzed for enzymes and blood chemistries. RESULTS: Gross observations showed mediastinal thickening and adhesions with doxycycline, and threadlike adhesions with talc. Autologous blood was only slightly more effective than a chest tube alone. Talc significantly increased angiotensin converting enzyme activity in serum, whereas doxycycline changed liver function enzymes and produced tissue toxicity. CONCLUSIONS: Doxycycline produced effective pleurodesis but yielded remarkably severe local effects. The distant sequelae of talc and doxycycline pleurodesis-histologic changes in the contralateral lung and serum enzyme elevations-suggests undesirable systemic effects for the commonly used agents, and autologous blood exhibited no significant pleurodesis, short-term. The search for the ideal agent for chemical pleurodesis continues.

Efficacies of ofloxacin, rifampin, and clindamycin in treatment of Staphylococcus aureus abscesses and correlation with results of an in vitro assay of intracellular bacterial killing.

We studied the efficacies of ofloxacin, rifampin, and clindamycin in a Staphylococcus aureus abscess model and seven antimicrobial regimens in an intracellular killing assay. Ofloxacin plus rifampin was the most effective regimen in the abscess model, and rifampin and ofloxacin were the most active regimens in the intracellular killing assay.

Soluble versus cell-bound CD4, CD8 from bronchoalveolar lavage: correlation with pulmonary diagnoses in human immunodeficiency virus-infected individuals.

Identification and assessment of cell populations in bronchoalveolar lavage (BAL) specimens may he used to follow the course of a disease state or response to specific therapy. Beyond cellular assessment, there are indications that the presence and quantity of soluble surface antigens released from activated cells may lead to improved understanding and facilitated diagnosis of a number of disease states. This study evaluated soluble markers (sCD4 and sCD8) in BAL and serum from HIV-infected individuals undergoing diagnostic bronchoscopy, and compared these values to flow cytometry-quantified BAL and peripheral blood cell CD4 and CD8. Patient pulmonary diagnosis (based on cytology and microbiology) was compared with patient blood and BAL-soluble and cell-bound CD4 and CD8 to determine the relationship of these markers to disease states in this population. Serum sCD8 in patients with fungal infections was significantly elevated above sCD8 in patients with Pneumocystis carinii or pulmonary bacterial infections, p = 0.0001. BAL sCD4/sCD8 ratio was also significantly different in patients with bacterial vs. fungal pulmonary infections, p = 0.01. These findings suggest that soluble markers, particularly elevated sCD8, may be an important indication of pulmonary disease progression in these HIV+ patients with fungal infections.

Azithromycin in an experimental Staphylococcus aureus abscess model.

We studied the efficacy and pharmacokinetics of azithromycin in a rabbit tissue-cage Staphylococcus aureus abscess model. A dosage of 15 mg/kg/day azithromycin was administered to rabbits with 24 h or 2 week old infected tissue cages and to uninfected controls. Concentrations of azithromycin were higher in the infected compared with the uninfected tissue cages. Azithromycin was effective in reducing the bacterial concentrations in both groups of infected tissue cages by approximately 3 log10 cfu/mL compared with untreated controls after 8 days of therapy. Fifty percent of the 24 h and 29% of the 2 week infected tissue cages became culture-negative.

Reactivity of the glycocalyx of endocarditis-producing viridans group streptococci.

We correlated quantity of streptococcal polysaccharides and endocarditis production by those bacterial strains. To investigate this finding further, we studied the composition of the glycocalyx using a spectrophotometric assay and lectin analysis of exopolysaccharides from endocarditis- and non-endocarditis-producing strains of viridans streptococci. Identical weights of glycocalyx from the clinical endocarditis isolates produced significantly different absorbances as compared with the nonendocarditis isolates (P < 0.0012, Wilcoxon rank test). Lectin-binding experiments showed that endocarditis-producing streptococci contained increased amounts of glucose, galactose, sialic acid, and mannose. These data suggest that the glycocalyx of endocarditis-producing viridans streptococci is both qualitatively and quantitatively different from non-endocarditis-producing isolates. These differences can be measured in vitro.

The effect of zinc on microbial growth and bacterial killing by cefazolin in a Staphylococcus aureus abscess milieu.

Microbial growth and antimicrobial bacterial killing are both diminished in abscesses. It was postulated that zinc depletion in abscesses, perhaps secondary to a neutrophil protein resembling calprotectin, may be partly responsible for these effects. In a rabbit tissue-cage abscess model, pooled abscess supernatant concentration of zinc was < 1.53 microM. The addition of 41.7 microM zinc had no effect on Staphylococcus aureus growth or the bacterial killing effect of cefazolin in serum. In abscess fluid supernatants, bacterial growth without antibiotic and bacterial killing by cefazolin were both enhanced by the addition of zinc. Fractionation of the abscess fluid with ultrafiltration membranes showed that these effects could be reproduced with the fraction between 30 and 50 kDa. These findings suggest that a protein in abscess fluid supernatants that resembles the neutrophil protein calprotectin may, through its zinc binding effects, inhibit microbial growth within an abscess but also inhibit the activity of bactericidal antibiotics.

beta-Lactamase-mediated inactivation and efficacy of cefazolin and cefmetazole in Staphylococcus aureus abscesses.

12694668 Clinical reports and animal models have demonstrated that cefazolin may have decreased efficacy against some strains of Staphylococcus aureus because of type A beta-lactamase-mediated hydrolysis. We sought to measure biologically active cefazolin concentrations within abscesses with high concentrations of S. aureus and compare the concentrations with those of cefmetazole, a beta-lactamase-stable cephamycin. A type A beta-lactamase-producing strain of S. aureus with a demonstrated inoculum effect against cefazolin (MIC at an inoculum of 5 x 10(5) CFU/ml, 1.0 micrograms/ml; MIC at an inoculum of 5 x 10(7) CFU/ml, 32.0 micrograms/ml) but not cefmetazole (MICs at inocula of 5 x 10(5) and 5 x 10(7) CFU/ml, 2.0 micrograms/ml) was used. Cefazolin or cefmetazole (100 mg/kg of body weight every 8 h for 8 days) was administered to rabbits with infected tissue cages. No differences in the concentrations of the two drugs in the uninfected tissue cages were observed. Higher concentrations of cefmetazole than cefazolin were found in infected tissue cages at day 3 (5.9 +/- 0.7 versus 2.2 +/- 0.3 micrograms/ml; P < 0.01), day 5 (9.1 +/- 2.6 versus 3.6 +/- 0.7 micrograms/ml; P = 0.02), and day 8 (9.4 +/- 1.4 versus 4.8 +/- 0.9 micrograms/ml; P = 0.01) after infection. Cefazolin and cefmetazole were equally effective in reducing the bacterial concentration in the abscess. In vitro experiments demonstrated greater cefazolin than cefmetazole degradation by S. aureus, but the differences were greater in serum than in abscess fluid supernatants. We conclude that abscess cefazolin concentrations are diminished by type A beta-lactamase-producing S. aureus, but this did not affect drug efficacy in this model.

Effects of dopamine on T-lymphocyte proliferative responses and serum prolactin concentrations in critically ill patients.

OBJECTIVES: Dopamine is currently used in the ICU for its vasopressor, renal vasodilating, and cardiac inotropic properties. Animal studies have shown both endocrine and T-lymphocyte alterations with dopamine agonist administration. The relationships between exogenous dopamine and patient hormonal and lymphocyte proliferative responses have not been evaluated in the critically ill patient. These findings furnished the impetus for the present study. DESIGN: Prospective, controlled, clinical study. PATIENTS AND METHODS: All patients admitted to the ICU at Truman Medical Center were evaluated for admission into the protocol, excluding patients whose medications or diseases produced effects in the study-dependent variables. Before institution of dopamine therapy, blood samples were taken for T-cell analysis and prolactin measurement. Daily, early morning blood samples were taken if the dopamine infusion was > 5 micrograms/kg/min for 4 hrs during that 24-hr period. An early morning postdopamine sample was taken on the first day after dosage discontinuation. Control blood samples for determination of T-cell and prolactin responses were drawn from ICU patients who did not receive dopamine. A severity-of-disease score (Acute Physiology and Chronic Health Evaluation [APACHE II] score) was recorded for all patients. MAIN RESULTS: Serum prolactin concentrations decreased > 90% (p < .001) within hours in all patients receiving dopamine infusions at study dose limit or above. The in vitro T-cell proliferative response to concanavalin A decreased (a transitory response) in patients receiving a dopamine infusion (p < .001). Dopamine infusions in medical ICU patients produced an immediate and profound reduction in serum prolactin concentrations in both males and females. An immediate transitory decrease in patient T-cell response to concanavalin A stimulation in vitro was seen in patients receiving dopamine. CONCLUSIONS: The data suggest the possibility of altered endocrine and immune function as a corollary of therapeutic concentrations of dopamine in critically ill patients.

Efficacies of various antimicrobial agents in treatment of Staphylococcus aureus abscesses and correlation with in vitro tests of antimicrobial activity and neutrophil killing.

A rabbit perforated-capsule model was utilized to study antimicrobial efficacy in treating 2-week-old Staphylococcus aureus abscesses. Animals received either ciprofloxacin (30 mg/kg), cefazolin (100 mg/kg), or ciprofloxacin (30 mg/kg) plus rifampin (20 mg/kg) every 8 h for 8 days or no antibiotic. Antibiotic levels within the abscess exceeded the MIC for the test organism. At the end of treatment, ciprofloxacin was no more effective than the control, animals receiving cefazolin had a mean log10 fall of 2.41 CFU/ml, and animals receiving ciprofloxacin plus rifampin had a mean log10 reduction of 5.06 CFU/ml (P = less than 0.01). Six days after completion of therapy, all abscesses in animals receiving ciprofloxacin plus rifampin were culture negative. Surviving organisms in animals receiving ciprofloxacin or rifampin did not develop resistance to the treatment antibiotics. In vitro time-kill curves performed with logarithmic- and stationary-phase organisms in broth, serum, and abscess fluid supernatants did not correlate with the in vivo results. Neutrophil killing studies of S. aureus pretreated with antibiotics revealed greater killing of organisms pretreated with ciprofloxacin plus rifampin than of those pretreated with cefazolin or ciprofloxacin alone. In conclusion, ciprofloxacin plus rifampin was effective therapy in this staphylococcal abscess model, compared with the moderate efficacy of cefazolin and no effect observed with ciprofloxacin alone. Enhanced neutrophil killing of S. aureus pretreated with antibiotics may be an important mechanism by which bacteria are killed in suppurative infections.

Association of cell-adherent glycocalyx and endocarditis production by viridans group streptococci.

To assess the role of glycocalyx production in the pathogenesis of endocarditis caused by viridans group streptococci in adult patients, glycocalyx production was examined for 49 blood culture isolates. The tryptophan assay, a quantitative spectrophotometric test, was used to measure cell-adherent glycocalyx production. Absorbance values of the isolates that produced endocarditis were significantly higher (means, 0.166 versus 0.060 [P less than 0.001]). At a breakpoint of absorbance of 0.120, the sensitivity of the test was 0.83, the specificity was 0.96, and the predictive value was 0.95. These data suggest that the in vitro tryptophan assay of glycocalyx production by viridans group streptococci has potential value as a predictor of clinical pathogenicity.

Bactericidal capacity of neutrophils in rabbits with experimental acute and chronic abscesses.

Bacteria persist within abscesses despite the presence of neutrophils, and patients with abscesses have high rates of subsequent infections. A model was developed to study neutrophil function in rabbits with Staphylococcus aureus abscesses. Blood neutrophils from rabbits with 2-week-old (chronic) abscesses had diminished bactericidal capacity and decreased superoxide production compared with rabbits with 24-h (acute) abscesses. Rabbits with chronic abscesses did not produce serum opsonic factors that enhanced bacterial killing. A bactericidal assay performed with chronic abscess fluid in the suspending medium revealed inhibition of neutrophil killing. The inhibition could be replicated with a neutrophil lysate but not by an S. aureus supernatant. Rabbits with chronic abscesses have diminished blood neutrophil bactericidal capacity and superoxide formation, and the abscess fluid milieu is inhibitory to neutrophil function.

Neutrophil chemotaxis and adherence in vitro and localization in vivo in rabbits with Staphylococcus aureus abscesses.

Decreased neutrophil (PMN) function may contribute to an altered host defense system in hosts with bacterial abscesses but has not been well correlated to in vivo outcome. We have found that blood PMNs from rabbits with chronic (2-week) experimental Staphylococcus aureus abscesses have decreased chemotaxis in response to an S. aureus supernatant (370 +/- 130 microns migration vs 570 +/- 180 microns, p less than 0.05) and decreased adherence (11.5% +/- 13.2% vs 32.9% +/- 18.6%, p less than 0.005) compared with PMNs from animals with acute (24-hour) abscesses. No differences were found in chemokinesis, random migration, and chemotaxis in response to zymosan-activated serum. No plasma inhibitors of PMN chemotaxis or inhibitors of chemotaxins were found. Although animals with chronic abscesses had higher levels of circulating chemotaxins, in both groups of animals abscess chemotaxin levels were greater than the plasma chemotaxin level. Animals with a concomitant chronic abscess had less PMN influx into an acute abscess but also less bacterial growth within the abscess than animals without a concomitant chronic abscess. We conclude that rabbits with chronic staphylococcal abscesses have decreased chemotaxis and adherence measured in vitro and decreased PMN localization in vivo. In this model, these functions were not associated with increased bacterial proliferation in vivo.

Hyperbaric pressure effects measured by growth of a transplantable tumor in the C3H/HeN mouse.

Both hypobaric exposure at 0.5 atmospheres absolute (ATA) and hyperbaric pressure exposure at 3.5-8 ATA slowed transplantable tumor growth. These experiments detailed the hyperbaric pressure exposure. C3H/HeN-MTV+ mice, bearing the 16/C transplantable murine mammary adenocarcinoma and exposed to 18 days' treatment by a hyperbaric chamber at 3.5-8 ATA, had tumor weights that averaged 50-75% less than the tumor weights in mice caged at ambient ("sea level") pressure. A series of experiments was run to investigate this response to hyperbaric pressure exposure. After mice underwent continuous exposure to 3.5-8 ATA normoxic (normal oxygen) hyperbaric pressure with use of either argon or nitrogen inert gas, which began 3 days after tumor inoculation, tumors were removed at about 3 weeks' growth from these pressure-exposed mice and measured for growth by weighing. Final tumor weight in pressure-exposed experimental mice was significantly less than tumor weight in paired groups of tumor-bearing controls that received no hyperbaric pressure. Tumor weight was inversely related to pressure "dose," although the small pressure range produced an effect at all pressures used. The number of compression-decompression cycles to which the animals were subjected, however, was related positively to tumor weight at necropsy. Continued tumor growth in mice subjected to frequent pressure change (in conjunction with pressure exposure that otherwise limited tumor size) was unexplained by these experiments. The greatest difference between tumor weights in controls and pressure-exposed animals was seen with 2 weeks' continuous pressure exposure. A limited profile of blood tests was performed, and these reflected only minor, expected change in the pressure-exposed experimental animals. The data at hand did not suggest a mechanism by which chronic normoxic hyperbaric pressure limited tumor size.

Atmospheric pressure effects on tumor growth: hypobaric anoxia and growth of a murine transplantable tumor.

Inasmuch as solid tumor growth and some intervention methods for tumor control have often been related to the low oxygen levels in tumor tissue, and a special role for hypoxia, perhaps even in oncogenesis, has been suggested by observations of unexpectedly low tumor incidence in mice caged a lifetime in the environment of a simulated altitude, inbred C3H/HeN mammary tumor virus-positive mice bearing transplanted tumors (16/C murine mammary adenocarcinoma) were exposed to atmospheric pressure variants ranging from 0.33 to 2.0 in different sequences 24 hours/day. Breathing gases included air, 100% oxygen, and other nitrogen--oxygen combinations. Exposure to the pressure sequences was continuous, beginning on the third day after tumor inoculation and continuing until planned necropsy at 1, 2, or 3 weeks. Actual tumor weight was used as a measure of effect. Mice caged at simulated altitude had tumors that averaged 45% of the weight of control tumors. The maximum effect occurred with continuous 2-week exposure to 0.43 atm. beginning on day 3 of tumor growth. At necropsy, these experimental tumors weighed an average of 15% of the control tumor weight. Life-span studies showed a maximum of 36% increase in longevity in the hypobaric pressure-exposed mice when compared to that of unexposed controls.

Immunologic effects of morphine in rodents, rabbits, monkeys, and cats.

The effects of prolonged morphine administration on immunologic reactivity against morphine was studied in a number of animal species: rabbit, monkey, guinea pig, rat, and cat. Some evidence for increased serum binding of 14C-labeled morphine was noted after morphine treatment in all test species, with the rabbit the best responder and the cat showing little or no response. In addition to measurements on serum binding of 14C-labeled morphine, other methods (measurement of serum binding of 14C-labeled codeine and methadone, competitive inhibition tests, radial immunodiffusion, and passive hemagglutination) were used for one or more of the species. Overall, results with these test methods have shown that prolonged morphine administration can result in immunologic responsiveness to morphine in animals.

Effect of antilymphocyte serum (ALS) on shock in rats.

Effects of treatment with rabbit antirat anti-lymphocyte serum and globulin (ALS and ALG) on shock survival were studied in Sprague-Dawley derived male rats. Because of their known cytotoxic capability, it was postulated that lymphocytes might play a role in the pathogenesis of shock and that suppression of lymphocyte function by ALS/ALG treatment should then protect against shock. Shock models used were tourniquet, endotoxin, and hemorrhagic shock. Protection against tourniquet shock was found for ALS made against thymocytes but not for ALS against spleen cells or lymph node cells. The shock-protective factor was found in the ALG-containing serum fraction but not in the primarily albumin fraction. No significant protection was found for ALS treatment against either endotoxin or hemorrhagic shock. ALS effects on blood cell counts, reticulo endothelial system clearance, and inflammation were studied to help identify effects of ALS on shock survival. It was concluded from these studies that thymic or thymus-processed lymphocytes could play a role in the pathogenesis of shock but that multiple effects of ALS/ALG treatment necessitate further studies to elucidate any role for lymphocytes in shock.

Immunologic effects of morphine administration in rabbits.

Long-term effects of morphine administration or immunologic test responses were studied in female rabbits. Implantation of morphine-containing pellets was found to be more effective than injection of morphine sulfate solutions in promoting increased serum binding of 140-morphine. A large part of the increased morphine binding by sera associated with administration of morphine was found in serum fractions containing gamma-globulin and was absent in gamma-globulin-free fractions. These sera showed some degree of specificity for the morphine configuration in tests with other narcotics. They also gave positive immunologic test reactions in passive hemagglutination and radial immunodiffusion tests involving serum albumins conjugated with morphine derivatives. Other evidence for immunologic responsiveness against morphine by morphine-pretreated rabbits was shown by cutaneous hypersensitivity reactions against morphine-carrier conjugates and by a diminution of the serum morphine-binding response in rabbits given an immunosuppressive dose of cyclophosphamide. Failure of naloxone, a morphine antagonist, to alter the serum morphine-binding response suggested that serum levels of the morphine-binding globulin studied here were not direclty related to morphine withdrawal.