Characterization of beta-lactam-resistant Bacteroides fragilis isolates by use of PCR fingerprinting

PCR fingerprinting was used for characterization of 35 beta-lactam-resistant Bacteroides fragilis strains isolated in Sweden and Hungary. Ten B. fragilis strains showed unique PCR fingerprints by use of the M13 core primer. Their main product was a DNA fragment with a length of 2000-bp which was absent in the other 25 strains and the reference strain B. fragilis ATCC 25285. The 2000-bp fragment from four imipenem-resistant strains gave rise to positive reactions in a specific PCR for detection of ccrA. Printed by the T3B primer, five B. fragilis strains, including the imipenem-resistant strains showed unique PCR fingerprints. The investigated imipenem-resistant strains produced carbapenem-hydrolysing metallo-beta-lactamases. The study indicates that the unique PCR fingerprinting profiles shown in highly beta-lactam resistant B. fragilis strains are correlated to antimicrobial resistance. The PCR fingerprinting technique is a useful tool for differentiation of Bacteroides fragilis strains with high-level beta-lactam resistance.

Lipid peroxidation of lung surfactant in experimental neonatal group B streptococcal pneumonia

Group B streptococcal (GBS) pneumonia, with neutrophilic granulocytes immigrating into the lungs, may occur in neonates. The incidence is particularly high among preterm infants, who often are treated with exogenous surfactant. We have previously demonstrated in vitro that neutrophils stimulated by GBS cause lipid peroxidation (LPO) and functional impairment of lung surfactant. The present study aimed at evaluating LPO of exogenous lung surfactant (Curosurf) and the protective effect of the natural antioxidant, vitamin E in immature ventilated newborn rabbits with experimental neonatal GBS pneumonia. There was a prominent proliferation of GBS in the lungs of animals treated with surfactant and ventilated for 5 h. GBS-infected rabbits had a higher LPO of lung lavage fluid than non-infected ones. The LPO could be diminished using vitamin E, which, however, did not affect bacterial proliferation. During the 5-h incubation period, mean lung-thorax compliance values were significantly lower in GBS-infected than in noninfected animals. We speculate that addition of vitamin E to exogenous surfactant preparations may improve their resistance to LPO and make them more suitable for treatment of neonates with pneumonia.

Antibodies against a truncated Staphylococcus aureus fibronectin-binding protein protect against dissemination of infection in the rat

Staphylococcus aureus bacteraemia (SAB) originating from local infections can lead to severe secondary infections such as endocarditis. The protective effect of antibodies against secondary infections was studied in a rat model, where a local joint infection leads to bacteraemia and endocarditis on damaged aortic valves. In this study, immunizations with a truncated D2-domain of the S. aureus fibronectin-binding protein displayed on a cow-pea mosaic virus (CPMV-D) carrier induced protection against endocarditis (P < 0.05). Opsonization of S. aureus with antibodies raised against CPMV-D stimulated both neutrophil activity and macrophage phagocytosis in vitro. Furthermore, intravenous administration of these antibodies protected mice from weight loss due to SAB.

Effect of surfactant and specific antibody on bacterial proliferation and lung function in experimental pneumococcal pneumonia

OBJECTIVE

To investigate the effect of surfactant and specific antibody on bacterial proliferation in experimental pneumococcal pneumonia.

METHODS

Near-term newborn rabbits received a standard dose (10(7)) of type 3 pneumococci via the airways. Control animals were sacrificed 1 minute later. Other animals were ventilated for 5 hours and treated via the tracheal cannula with surfactant (Curosurf 200 mg/kg), a mixture of surfactant and a polyclonal antipneumococcal antibody, the antibody without surfactant, or saline.

RESULTS

There was a significant bacterial proliferation in lung tissue in all animals ventilated for 5 hours. Bacterial growth, expressed as log10 colony forming units (CFU) per gram of lung tissue was less prominent in animals treated with a mixture of surfactant and specific antibody than in animals treated with antibody alone (median, 7.51, range, 6.80--7.70 vs. median, 7.92, range, 7.07--8.50; P < 0.05). Dynamic lung-thorax compliance was improved with surfactant or surfactant plus antibody in comparison with saline or antibody alone.

CONCLUSIONS

The data suggest that the suppressive effect of the antibody on bacterial proliferation becomes evident only when surfactant is administered together with the antibody.

Direct and phagocyte-mediated lipid peroxidation of lung surfactant by group B streptococci

In newborn infants, group B streptococci (GBS) often cause pneumonia, with polymorphonuclear leukocytes (PMN) migrating into the lungs. Because surfactant therapy may be needed in such patients, we evaluated the interaction between GBS or GBS-stimulated PMN and a surfactant preparation (Curosurf) in vitro. The superoxide production of GBS strains or GBS-activated PMN was measured, using the nitroblue tetrazolium (NBT) test and the subsequent lipid peroxidation (LPO) as the content of malondialdehyde (MDA) and 4-hydroxyalkenals (4-HNE). The growth of GBS in surfactant was determined and related to the LPO. Finally, the effect of LPO on surfactant activity, caused by GBS-stimulated PMN, was assessed by measuring dynamic surface tension in a pulsating bubble surfactometer. Curosurf diminished the NBT reduction by both live GBS and GBS-stimulated PMN. Surfactant was peroxidized by reactive oxygen species (ROS) from both GBS and GBS-stimulated PMN in a time-dependent manner. Vitamin E significantly reduced the peroxidation level of surfactant in both cases. Surfactant peroxidation was associated with a reduction in the number of live bacteria. The biophysical activity of Curosurf was impaired by GBS-stimulated PMN, as reflected by increased minimum surface tension during cyclic compression. These findings indicate that Curosurf undergoes LPO by ROS produced by GBS and/or PMN. We speculate that exogenous surfactant preparations should be supplemented with vitamin E or another antioxidant, when given to infants with GBS pneumonia.

Lipid peroxidation caused by oxygen radicals from Fusobacterium-stimulated neutrophils as a possible model for the emergence of periodontitis

OBJECTIVE

The possible contribution of bacteria and polymorphonuclear neutrophils (PMN) to the disease process of periodontitis was evaluated.

DESIGN

Fusobacterium nucleatum has been associated with chronic adult periodontitis. Intracellular production and extracellular release of reactive oxygen species (ROS) by PMN stimulated by fusobacteria were evaluated. To estimate the potential extracellular damage that might be caused by the ROS, the lipid peroxidation (LPO) of an exogenous phospholipid, Intralipid, was assayed.

METHODS

The ROS production of PMN was studied by the nitroblue tetrazolium and chemiluminescence tests. The levels of malonaldehyde (MDA) and 4-hydroxyalkenals were used to indicate LPO.

RESULTS

Fusobacterium nucleatum strains stimulated neutrophils to produce a large amount of ROS, independently of plasma complement factors. The two strains tested induced considerable intracellular, but no extracellular chemiluminescence responses during the first hour, indicating that ROS were released into phagosomes. However an incubation period of 4 h, in the presence of the extracellular lipid resulted in a high degree of LPO, presumably caused by ROS release from the Fusobacterium-stimulated PMN. ROS production and lipid peroxidation could be counteracted by vitamin E.

CONCLUSION

In periodontitis local bacteria might stimulate PMN to release ROS, which cause inflammation and destruction.

Lipid peroxidation by alveolar macrophages challenged with Cryptococcus neoformans, Candida albicans or Aspergillus fumigatus

Increased formation of oxygen radicals has previously been shown for alveolar macrophages (AM) challenged with Cryptococcus neoformans cells opsonized with fresh serum or polyclonal immunoglobulin G. AM show similar responses to Candida albicans or Aspergillus fumigatus. Oxygen radicals are capable of damaging various macromolecules, including lipids. In the present study, lipid peroxidation (LPO) caused by AM incubated with the fungi was examined in the presence and absence of lung surfactant. The level of malonaldehyde was used as an indicator of LPO. AM damage was examined by electron microscopy (EM), by trypan blue exclusion and by counting the AM loss from culture dish to supernatant. Stimulation of AM by each fungus increased cellular LPO but did not affect AM viability. A slight surfactant LPO induced by AM alone was shown with significantly increased values after addition of each fungus. EM studies showed that dense lipid droplets, presumably consisting of oxidized lipids, were ingested in high amounts together with C. neoformans cells that had been opsonized in fresh serum, and in low amounts in combination with C. albicans. These processes were accompanied by increased numbers of AM in the supernatants. LPO and detachment of AM were counteracted by vitamin E. In the lungs, AM exposed to one of these fungal pathogens might promote peroxidation of surfactant lipids.

Cytokine, elastase and oxygen radical release by Fusobacterium nucleatum-activated leukocytes: a possible pathogenic factor in periodontitis

Periodontitis is characterised by tissue destruction caused by reactive oxygen species (ROS) and proteolytic enzymes, which are released by the interaction between bacteria and phagocytes. We estimated the ability of Fusobacterium species to induce release of tissue destructive and proinflammatory mediators from in vitro activated peripheral leukocytes. ROS was measured with the nitroblue tetrazolium (NBT) method, elastase with a specific chromogenic substrate and cytokines, including interleukin 1beta (IL-1beta), tumour necrosis factor alpha (TNF-alpha), and interleukin 8 (IL-8) with a sandwich ELISA method. Various clinical isolates of unopsonized Fusobacterium species stimulated the neutrophils to an increased NBT- reduction. IL-1beta, TNFalpha, IL-8 and elastase were released in significantly higher levels from neutrophils stimulated by Fusobacterium species. In conclusion, unopsonized Fusobacterium species can induce increased production of oxygen radicals, cytokines and elastase from leukocytes activated in vitro.

Treatment of experimental Cryptococcus neoformans infection in newborn rabbits by airway instillation of specific antibody and surfactant

Cryptococcosis in AIDS patients has a slow response to antifungal chemotherapy, and passive antibody treatment has thus been considered as an adjunct. Polyclonal anticryptococcal IgG dissolved in a suspension of modified natural surfactant was given intratracheally to near-term rabbits. Killing of Cryptococcus neoformans within the lungs was determined by counting the colony forming units (cfu). After 5 h a significant decrease in cfu was observed in rabbits treated with the IgG-surfactant mixture compared with control animals receiving saline. In conjunction with conventional therapy, the combined treatment of IgG-surfactant given by bronchoscopy might be used in high-risk patients to enhance killing of the yeast within the lungs.

Interaction between lung surfactant and nitric oxide production by alveolar macrophages stimulated by group B streptococci

The major etiologic agent in neonatal pneumonia and meningitis is group B streptococci (GBS). Nitric oxide (NO) production by alveolar macrophages (AM) in response to Gram-positive bacteria such as GBS and the effect of surfactant on this production have received little attention. We studied production of NO by GBS-stimulated AM using the Griess reaction, the effect of lung surfactant on this NO production, and the possible lipid peroxidation (LPO) of surfactant caused by NO. The LPO test was used to measure surfactant peroxidation. Heat-killed and live GBS were found to stimulate NO production by rat alveolar macrophages, and the presence of interferon gamma (IFN-gamma) increased this stimulation in a synergistic manner. Curosurf(R), the natural surfactant used in our study, significantly reduced NO production in various sets of experiments. Lipid peroxidation of surfactant was noted when NO was produced by stimulated AM, a phenomenon that could be suppressed by NG-monomethyl L-arginine (L-NMMA), the inhibitor of NO synthase. In the lung of GBS-infected neonates, nitric oxide produced by AM might contribute to the destruction of surfactant caused by inflammatory cells. Pediatr Pulmonol. 2000; 30:106- 113.

Mercury intolerance in relation to superoxide dismutase, glutathione peroxidase, catalase, and the nitroblue tetrazolium responses

Through percutaneous provocation with metallic mercury and phenyl mercuric acetate in patients stating the presence of subjective psychosomatic symptoms following dental amalgam treatment, it has been possible to categorize and score two extreme groups of patients, mercury-intolerant and mercury-tolerant patients reacting and not reacting, respectively, to low doses of mercury. The intolerant patients had a high psychosomatic score and the tolerant patients had a low or null score when exposed to low doses of the two mercury compounds. Determination of the scavenger enzymes superoxide dismutase, glutathione peroxidase, and catalase showed no significant differences between the mercury-intolerant and the mercury-tolerant patients and the controls. The activity of superoxide dismutase and the quantitative psychosomatic score elicited by either metallic mercury or phenyl mercuric acetate showed a positive correlation. On the other hand, analyses of the psychosomatic score and the areas under the curves of the nitroblue tetrazolium test response showed negative correlations. The results indicate that the oxidative metabolism and, in particular, superoxide dismutase may be perturbed in mercury-intolerant patients.

In vitro effect of lung surfactant on alveolar macrophage defence mechanisms against Cryptococcus neoformans

The effects of a modified natural porcine surfactant (Curosurf) on phagocytosis and killing of Cryptococcus neoformans by alveolar macrophages and on the production of superoxide anions were investigated in vitro. Attachment and ingestion were evaluated separately by a fluorescent quenching technique. The nitroblue tetrazolium reduction test was used as an indirect measurement of superoxide anion production. Killing was assessed by a colony-forming assay. Surfactant induced increased ingestion of C. neoformans, unopsonized as well as opsonized with fresh serum or anticryptococcal polyclonal IgG. Surfactant had, however, no effect on the attachment or killing of unopsonized or opsonized C. neoformans by the alveolar macrophages. In addition, the enhancement of the oxidative metabolism of the macrophages after stimulation with opsonized yeast was impaired, although the killing was not affected. This study indicates that in vitro Curosurf can influence the alveolar macrophage defence against C. neoformans by enhancing its ingestion and by interacting with the superoxide anions release from alveolar macrophages stimulated with fresh serum or anticryptococcal polyclonal IgG opsonized yeast cells.

Combined treatment with surfactant and specific immunoglobulin reduces bacterial proliferation in experimental neonatal group B streptococcal pneumonia

Neonates suffering from group B streptococcal (GBS) pneumonia often lack type-specific opsonizing antibodies. We studied the influence of combined intratracheal treatment with surfactant and a specific antibacterial polyclonal antibody (IgG fraction) on bacterial proliferation and lung function in an animal model of GBS pneumonia. Near-term newborn rabbits received an intratracheal injection of either the specific IgG antibody, nonspecific IgG, surfactant, a mixture of surfactant and the antibody, or 0.9% saline. At 30 min the rabbits were infected with a standard dose (10(8)) of the encapsulated GBS strain 090 Ia. After 5 h of mechanical ventilation the mean estimated increase in bacterial number in lung homogenate (log10 colonies/g) was 0.76 in the antibody group, 0.92 in the nonspecific IgG group, 0.55 in the surfactant group, and 1.29 in the saline group. A mean decrease in bacterial number (-0.05) was observed in the group that received combined treatment with surfactant and antibody (p < 0.05 versus all other groups). Lung-thorax compliance was significantly higher in both groups of surfactant-treated animals compared with saline or IgG treatment. We conclude that in experimental neonatal GBS pneumonia combined treatment with surfactant and a specific immunoglobulin against GBS reduced bacterial proliferation more effectively than either treatment alone.

Production of nitric oxide by rat alveolar macrophages stimulated by Cryptococcus neoformans or Aspergillus fumigatus

Cryptococcus neoformans and Aspergillus fumigatus are airborne fungi and the alveolar macrophages (AM) constitute a first line of host defence against both pathogens. We investigated the ability of rat AM to produce nitric oxide (NO) when challenged in vitro with C. neoformans, A. fumigatus conidia or inert silica particles alone and together with interferon gamma (IFN-Gamma). The role of NO in the killing of C. neoformans as well as the relationship between phagocytosis of the yeast or A. fumigatus conidia and NO production by AM were studied. Both fungi, but not the inert particles induced a small but significant increase in NO production by AM. A synergistically enhanced NO production by AM was observed when each fungus, but not silica particles, were incubated together with IFN-Gamma. AM treated with IFN-Gamma and challenged with C. neoformans showed higher killing activity than untreated AM, a finding that correlated with increased NO production by AM. Both effects were reduced by an inhibitor of NO synthesis. Increased NO production by IFN-Gamma activated AM was found together with an increased accumulated attachment of A. fumigatus conidia and serum opsonized, but not unopsonized C. neoformans. The IFN-Gamma dependent increase in accumulated attachment of the fungi might be responsible for the synergistic effect of the fungi and IFN-Gamma on the NO production. Our data suggest that activated rat AM might efficiently use the antimicrobial nitric oxide system in the defence against these pathogens in the normal host.

Phagocyte-induced lipid peroxidation of lung surfactant

Surfactant therapy is given routinely to premature newborns with respiratory failure. However, alterations in surfactants have been shown to be a significant factor in some forms of respiratory failure in newborns in animal models of lung injury. To investigate whether antioxidant supplementation might help to protect exogenous surfactant from damage by oxygen free radicals, we examined the influence of vitamin E in combination with surfactant on superoxide production as estimated by the nitroblue tetrazolium reduction test, and measured surfactant peroxidation with a new colorimetric method with or without addition of superoxide dismutase (SOD) or vitamin E. Our results showed that surfactant interacts with free radicals; surfactant reduced superoxide production by neutrophils and was peroxidized when incubated with resting and with stimulated cells. Vitamin E supplementation decreased superoxide radical production and in a dose-dependent manner decreased surfactant peroxidation. The decrease in lipid peroxidation by SOD was not significant. These findings suggest that phagocytes induce lipid peroxidation of lung surfactant, a reaction that might be prevented by antioxidants.

Phagocyte-induced lipid peroxidation of different intravenous fat emulsions and counteractive effect of vitamin E

Unsaturated fatty acids, a major component of fat emulsions used in parenteral nutrition, are prone to peroxidation which is an important feature of oxygen-associated tissue damage. We used the nitroblue tetrazolium (NBT) reduction test to measure the production of superoxide radicals by stimulated polymorphonuclear neutrophils (PMN) in the presence of different fat emulsions: Intralipid (containing 100% long-chain triacylglycerols, LCT), Vasolipid (a physical mixture of 50% LCT and 50% medium-chain triacylglycerols, MCT) and Structolipid (structured triacylglycerols containing 63% LCT and 37% MCT). We measured the amount of malonaldehyde (MDA) and 4-hydroxyalkenal to determine the lipid peroxidation of the three fat emulsions in the presence of stimulated neutrophils. Further, we investigated the role of vitamin E (alpha-tocopherol) in preventing lipid peroxidation in vitro. The results showed that the values of NBT reduction of PMN were significantly decreased in each of the three fat emulsions and that increasing concentrations of fat emulsions were associated with decreased values of NBT reductions, in a dose-dependent way (P<0.001). There were, however, no statistically significant differences between the values of the three different types of fat emulsions (P>0.05). Lipid peroxidation increased significantly in the presence of all three types of fat emulsions, and was more pronounced for Intralipid than for Vasolipid and Structolipid after 1 and 2 h of incubation with resting as well as with stimulated phagocytes. The increased lipid peroxidation of the fat emulsions was markedly reduced by vitamin E, and the inhibition was concentration dependent. In conclusion, lipid peroxidation in vitro is more pronounced when PMNs are incubated with fat emulsions. This increase in lipid peroxidation can be reduced by adding vitamin E to the fat emulsions.

Lipid peroxidation of lung surfactant by bacteria

The epithelium of the lung is lined with extracellular pulmonary surfactant. This is the surface that invading bacteria first come into contact with when they enter the alveoli. As bacteria become established and interact with this layer, various characteristics of surfactant may become altered. We studied free radical production by three bacterial species, group B streptococci, Escherichia coli, and Pseudomonas aeruginosa, as well as the effect of two concentrations of lung surfactant (Curosurf at 0.04 and 0.4 mg/ml) on this production estimated by the nitro blue tetrazolium reduction test. We also measured the lipid peroxidation of surfactant at various incubation times (0-20 h), using a LPO-586 test kit. In addition, the effect of vitamin E as an antioxidant in a concentration of 0.5 microM was determined by the lipid peroxidation test. We found that the nitro blue tetrazolium reduction by the three bacterial species and lipid peroxidation of lung surfactant increased with time. Vitamin E reduced the lipid peroxidation of this surfactant. By measuring bacterial growth at various incubation times we showed that lung surfactant was bactericidal to group B streptococcal and E. coli strains and that P. aeruginosa strains were resistant to surfactant. We conclude that bacteria, probably by their production of reactive oxygen species, cause lipid peroxidation of lung surfactant.

Fungal prophylaxis by reduction of fungal colonization by oral administration of bovine anti-Candida antibodies in bone marrow transplant recipients

Candida overgrowth and invasion constitute a serious threat with a high mortality in BMT recipients. Currently available topical antifungal prophylaxis is largely ineffective, and as resistance to existing, absorbable drugs for systemic use is rapidly developing, new forms of therapy are needed. We investigated the effect of oral treatment of BMT recipients with a bovine immunoglobulin product derived from animals immunized against several Candida species. The natural Candida colonization was first followed in 19 patients to establish the colonization pattern. Half of the patients were found to be colonized prior to transplantation and altogether 72% were colonized at some point during follow-up. Those with a high pre-transplant concentration of Candida in saliva (>100 CFU/ml) remained colonized throughout the BMT treatment period. The therapeutic effect was monitored in two other patient groups. The first group consisted of nine patients, where, due to a low number of primary colonized patients, response in colonized patients was suggestive of a therapeutic effect. In the second group, 10 patients with a high level of colonization (>100 CFU/ml) were given 10 g daily of the product in three divided doses. The results suggest a treatment-related reduction in Candida colonization in a majority (7/10) of patients and one patient became completely negative. As no adverse effects were noted, our findings encourage additional studies in immunocompromised, transplant patients.

Coagulase-negative staphylococci are the most common bacteria found in cultures from the deep portions of hidradenitis suppurativa lesions, as obtained by carbon dioxide laser surgery

The significance of bacterial findings in hidradenitis suppurativa (HS) is controversial. Interpretation of the results of bacteriological examinations from the surface of HS lesions is obscured by the possible contamination of resident skin bacteria. Bacteriological analysis of aspirates from deeper parts of HS is liable to show low sensitivity. We used a carbon dioxide (CO2) laser method to evaporate the diseased tissue level by level from the surface downwards, allowing concurrent sampling of bacteriological cultures from each level and thereby minimizing contamination with bacteria from the level above. In this study, 22 women and three men with a mean age of 35.3 years and a mean HS duration of 10.6 years were treated with this CO2 laser surgical method. Aerobic and anaerobic cultures from superficial and deep levels were taken during surgery. The regions treated were axillary in eight and perineal in 17 cases. Bacterial cultures were positive for one or more specimens from at least one level in all cases and from deep levels in all but three cases. Sixteen different species or sub-species were found. Staphylococcus aureus and coagulase-negative staphylococci (CNS) were the species most frequently found. Peptostreptococcus species and Propionibacterium acnes were not uncommon. S. aureus was detected in a total of 14 cases, six of which were from the deep levels. S. aureus was the sole bacterium isolated in two deep cultures. CNS were found in 21 patients and 16 of these isolates were from the deep levels. In nine of the 16 deep samples CNS were the only bacteria detected. These findings motivate a re-evaluation of the significance of bacteria in the progress of HS and in particular they suggest that CNS are true pathogens. It is known that foreign bodies aggravate the virulence of the CNS in surgical implants, and an environment which resembles that produced by a foreign body, as found in chronic HS tissue, serves to intensify the pathogenic properties of CNS in HS.

In vivo interaction between alveolar macrophages and Cryptococcus neoformans

In vivo interactions of rabbit alveolar macrophages (AM) and Cryptococcus neoformans, a yeast pathogenic for humans, were studied. As a control, inert silica particles of a similar diameter (5-6 microns) were used. Of 16 rabbits, 6 were instilled intratracheally with fluorescein-labelled heat-killed C. neoformans, 6 with fluorescein-labelled silica particles and 4 with saline only. After 24 h, the AM were collected by lung lavage, and phagocytosis, oxidative metabolism, phagolysosomal pH and morphology were studied. The accumulated number of yeasts attached to the AM was almost the same for C. neoformans as for the silica particles. The ingested fraction of C. neoformans was even higher than that of the silica particles. Quantitative NBT reduction by the AM, reflecting their oxidative metabolism, was markedly increased by exposure to C. neoformans for 24 h. The phagolysosomal pH was on the average lower in phagolysosomes with C. neoformans than with the silica particles, although approximately 2% of the phagolysosomes with C. neoformans had neutral pH. Phagolysosomes with neutral pH was not observed for silica particles. Electron microscopy showed presence of C. neoformans in phagolysosomes of AM. The conclusion of this study is that the phagocytic activity, oxidative metabolism and phagolysosomal pH AM against C. neoformans are significant 24 h after the exposure.

Neutrophil function and glutathione-peroxidase (GSH-px) activity in healthy individuals after treatment with N-acetyl-L-cysteine

The objective of this study was to evaluate the effect of N-acetyl-L-cysteine (NAC) on neutrophilic functions and as an antioxidant. NAC, 600 mg daily, given orally to healthy individuals for a period of 2 weeks, affected some functions of human neutrophilic granulocytes when tested in vitro. NAC treatment caused a decrease in the production of superoxide anions by stimulated neutrophils and the improvement of their phagocytic capacity although it did not affect their random or chemotactic migration. The level of glutathione peroxidase (GSH-px) in thrombocytes of the NAC-treated individuals was increased in comparison with the activity before treatment. These results suggest that NAC might act as a scavenger of oxygen-derived free radicals released by stimulated neutrophils and thereby protect the tissue against the radical caused injury as well as optimize phagocytosis.

Lung function and bacterial proliferation in experimental neonatal pneumonia in ventilated rabbits exposed to monoclonal antibody to surfactant protein A

Surfactant protein A (SP-A) increases the resistance of surfactant to inhibition by plasma and other proteins. In a previous study we found that a monoclonal anti-SP-A antibody (R 5) increased the sensitivity of surfactant to inhibition by fibrinogen in vivo and in vitro. SP-A has been shown to stimulate microbial phagocytosis and killing by alveolar macrophages. We hypothesized that using R 5 to inactivate SP-A in an animal model mimicking congenital group B streptococcal (GBS) pneumonia might result in increased bacterial proliferation and a deterioration in lung function. Newborn near term rabbits were delivered by Cesarean section, anesthetized, tracheotomized, and ventilated for 5 h in a plethysmograph system allowing measurement of dynamic lung-thorax compliance. Postnatally the animals received one intratracheal injection (5 ml/kg) of R 5, nonspecific IgG, or normal saline. At 30 min all animals received a standard dose of an encapsulated GBS strain by intratracheal injection. The number of bacteria (mean log10 CFU/g lung +/- S.D.; CFU = colony forming unit) was evaluated in lung homogenates. Histologic lung sections were judged by light microscopy. Bacterial proliferation was similar in rabbits treated with the monoclonal antibody (9.33 +/- 0.39; n = 14) and in control animals receiving saline (9.16 +/- 0.35; n = 14) or nonspecific IgG (9.26 +/- 0.31; n = 11). No significant differences were noted on the histologic analysis or in measurements of lung function. We conclude that intratracheal instillation of a monoclonal anti-SP-A antibody did not increase bacterial proliferation in GBS-infected newborn rabbits. These findings suggest that SP-A does not play an important role in protection against encapsulated GBS strains in the neonatal period.

Reaction of human alveolar macrophages to exposure to Aspergillus fumigatus and inert particles

In vitro interaction of human alveolar macrophages (AM) with heat-killed conidia from Aspergillus fumigatus and inert silica particles of similar size, about 3 microns, was studied. The conidia were phagocytized significantly faster by AM than were the control particles partly due to the faster rate of attachment but especially due to the faster rate of ingestion. Quantitative nitroblue tetrazolium (NBT) reduction by AM, reflecting their release of oxygen radicals, was increased by a factor of 2 to 3 in response to the conidia during phagocytosis. The silica particles induced a moderate but significant increase in NBT reduction. Conidia, but not silica particles, showed a considerable percentage (around 8%) of phagolysosomes with neutral pH after 3 h and a smaller percentage (around 1%) after 24 h of incubation. The pH of phagolysosomes with conidia tended to be higher after 3 h, but was significantly lower after 24 h than the pH of phagolysosomes with silica particles. Despite the markedly increased oxidative metabolism there was no increase in cytokine production [interleukins (IL) 6 and 8 and tumor necrosis factor alpha (TNF-alpha)] after exposure to conidia. The silica particles induced a significant decrease in IL-6 and IL-8 production and a tendency toward decreased production of TNF-alpha. The occurrence of phagolysosomes with neutral pH suggests unsealed phagolysosomes from which not only oxygen metabolites but also enzymes might escape from the cell. Lung damage may thus be the result of repeated or long-term exposure to Aspergillus conidia.

Alveolar macrophage reaction to Candida species

Candida species are increasingly important fungal pathogens. The reaction of rat alveolar macrophages (AM) to Candida albicans was compared with that to C. glabrata and C. krusei. Phagocytosis of C. glabrata was similar to that of C. albicans, but significantly slower for C. krusei due to reduced attachment. After opsonization, attachment of C. albicans and C. krusei to AM was significantly increased and there was no significant difference between the two species. The oxidative metabolism of AM with candida species was two to three times higher than that of the resting AM both during and 24 h after the phagocytosis. All three species showed a considerable fraction (5-10%) of phagolysosomes with pH > or = 6.5 after 3 h and a smaller percentage (1%) after 24 h.

Interaction between Cryptococcus neoformans and alveolar macrophages

Phagocytosis, oxidative metabolism and phagolysosomal pH of rat alveolar macrophages (AM) were studied at different points of time after challenge with Cryptococcus neoformans. Phagocytosis was evaluated using a fluorescent quenching technique which distinguishes between attached and ingested organisms. The nitroblue tetrazolium (NBT) test was used as an indirect measurement of the oxidative metabolism of the phagocytes. The pH of the phagolysosomes was measured using a cytofluorometric technique. Both the attachment and ingestion of serum opsonized C. neoformans by AM were slow during the first hours of incubation, but were considerable after 24 h. The oxidative metabolism of Am challenged with the yeast was insignificant during the first hour, but reached high levels after 24 h. Most phagolysosomes in AM with ingested cryptococci had a pH < 5.5. Our results indicate that these AM defence mechanisms, although poor during the first hours after exposure to the yeast, are of significance after 24 h. Thus, in the immunocompetent host the AM should prevent the dissemination of C. neoformans from the lungs.

Surfactant improves lung function and mitigates bacterial growth in immature ventilated rabbits with experimentally induced neonatal group B streptococcal pneumonia

AIMS

To study the influence of surfactant on lung function and bacterial proliferation in immature newborn rabbits with experimental group B streptococcal (GBS) pneumonia.

METHODS

Preterm rabbit fetuses (gestational age 28 days) underwent tracheotomy and were mechanically ventilated in a warmed body plethysmograph that permitted measurement of lung-thorax compliance. Fifteen minutes after the onset of ventilation the animals received either GBS or saline intratracheally; at 30 minutes, a bolus of saline or 200 mg/kg of a porcine surfactant (Curosurf) was administered via the airway. Bacterial proliferation was evaluated in lung homogenate at the end of the experiments and the results expressed as mean log10 cfu/g lung (SD). Animals receiving only saline (n = 20) or saline and surfactant (n = 20) served as controls.

RESULTS

The average survival time was about three hours in all groups. Infected animals receiving surfactant (n = 22) had significantly less bacterial growth (9.09 (0.45) vs 9.76 (0.91)) and improved lung function (compliance: 0.61 (0.14) vs 0.34 (0.19) ml/kg. cm H2O) than infected rabbits receiving saline at 30 minutes (n = 22).

CONCLUSION

Surfactant improves lung function and mitigates bacterial growth in preterm rabbits infected with group B streptococci.

In vitro interaction of alveolar macrophages and Aspergillus fumigatus

In vitro interaction of alveolar macrophages (AM) from rats with conidia from Aspergillus fumigatus and Aspergillus candidus as well as inert control particles (amorphous silica) of similar diameter (about 3 microns), was studied. Experimental observations showed that both kinds of conidia were phagocytized significantly faster by AM than were the control particles due to a faster rate of attachment, but even more so due to a faster rate of ingestion. Quantitative nitroblue tetrazolium reduction by AM reflecting their oxidative metabolism and oxygen radical release was increased in response to both kinds of conidia by a factor of 2-3 during the process of phagocytosis, as well as 24 hr after the onset of phagocytosis, compared to corresponding conditions with inert particles and to resting macrophages. The mean pH in phagolysosomes with each of the conidia tended to be higher after 3 hr but was significantly lower after 24 hr than in the phagolysosomes with the control particles. After 3 hr there was a considerable percentage (around 8%) of phagolysosomes with pH > or = 6.5 and after 24 hr there was still a small percentage (0.7%) of such phagolysosomes for each of the conidia. Such a fraction was not observed for the control particles. Electron microscopic studies showed passages between phagolysosomes and AM surface with both kinds of conidia. The occurrence of such unsealed phagolysosomes might explain the percentage of phagolysosomes with high pH. Hence, Aspergillus conidia in unsealed macrophage vacuoles mediate an increased oxygen radical release from the macrophages, a process which in the long run might cause lung damage.

Effect of N-acetylcysteine(NAC) treatment on HIV-1 infection: a double-blind placebo-controlled trial

OBJECTIVE

In a double-blind placebo-controlled trial, human immunodeficiency virus (HIV)-seropositive patients with a CD4 lymphocyte cell count of more than 200 x 10(6) . l-1 were randomised to receive either 800 mg N-acetylcysteine (NAC) or placebo for 4 months. Before treatment low plasma cysteine levels, high free radical activity in neutrophils in the presence of autologous plasma-measured by the nitroblue tetrazolium (NBT) test- and increased tumor necrosis factor (TNF)-alpha levels were found in the HIV positive patients.

RESULTS

After treatment the low plasma cysteine level in the NAC group increased to normal, and the decline of the CD4+ lymphocyte count before the study start, was less steep in the NAC group than in the placebo group after treatment. There was also a reduction in TNF-alpha level. However, NAC had no effect on the radical production by neutrophils, and although it did not increase the CD4+ cell count, it may have decreased the decline in CD4+ cells.

CONCLUSION

Further controlled trials with NAC are needed to determine whether it has a beneficial effect in the treatment of asymptomatic HIV-infected individuals.

Alveolar macrophage response to yeasts and inert particles

Interactions between alveolar macrophages (AM) from rats and a yeast with relatively high pathogenicity (Candida albicans), a yeast with low pathogenicity (Saccharomyces cerevisiae) and an inert control particle (amorphous silica) of similar diameters, 3-4 microns, were studied. Both yeasts were phagocytized significantly faster by AM than were the control particles and C. albicans significantly faster than S. cerevisiae. Quantitative nitroblue tetrazolium reduction by AM reflecting their oxidative metabolism was markedly increased in response to both fungi during the period of phagocytosis as well as 24 h after the phagocytosis. Macrophages with silica particles also showed a moderate but significant increase in oxidative metabolism 24 h after phagocytosis. Phagolysosomal pH was significantly higher for S. cerevisiae than the control particles after 3 and 24 h. pH in phagolysosomes with C. albicans tended to be higher after 3 h but was significantly lower after 24 h than in the phagolysosomes with silica particles. Both yeasts showed a considerable number (around 10%) of phagolysosomes with high pH > or = 6.5 after 3 h and a smaller percentage after 24 h. No such fraction could be seen for the control particles. Electron microscopy showed narrow passages from AM cell surface to phagolysosomes with particles. These passages might be more frequent in AM containing the yeasts and could explain the phagolysosomes with high pH.

Anticryptococcal activity by alveolar macrophages from rats treated with cortisone acetate during different periods of time

The effect of cortisone acetate (CA) treatment on the anticryptococcal activity by rat alveolar macrophages (AM) was investigated. The animals received a weekly dose of 5 mg CA during 1, 2, 3 or 4 weeks. Following the final dose the AM were collected by lung lavage and challenged with Cryptococcus neoformans. Parallel experiments with silica particles of a similar size were performed. The phagocytic function was assessed using a fluorescence method that distinguishes between attached and ingested particles. The oxidative metabolism was studied by the nitroblue tetrazolium (NBT) reduction test. The accumulated attachment (a measure of the attachment process) of cryptococci and silica particles per AM was significantly depressed after the third and fourth week of CA treatment. The ingested fraction (a measure of the ingestion process) of cryptococci but not of silica particles showed a small but significant decrease after the fourth week. The NBT reduction of the unstimulated AM and those stimulated with either the cryptococci or silica particles for 24 h was significantly reduced after the fourth week of treatment. In conclusion, these results demonstrate that high dose CA treatment primarily affects the attachment of the cryptococci to the AM and to a lesser extent also the ingestion process. In addition, it decreases the NBT reduction by AM in response to the yeast. The impairment of the AM anticryptococcal activity by high doses of CA constitutes a risk of dissemination of C. neoformans from the lungs.

Effect of surfactant on nitroblue tetrazolium reduction of polymorphonuclear leucocytes stimulated with type Ia group B streptococci

Activation of polymorphonuclear leucocytes (PMN) was investigated after incubation of adult human PMN and group B streptococci (GBS) type Ia with a type-specific polyclonal antiserum and a modified porcine surfactant (Curosurf). The level of oxidative metabolism of PMN was studied using a micromethod modification of the nitroblue tetrazolium (NBT) reduction test. GBS alone did not stimulate significant oxygen metabolite release from PMN, and incubation of PMN with surfactant alone resulted in decreased NBT reduction. After opsonization of GBS with a specific antibody, PMN were activated and the increased oxygen metabolite release was not suppressed when surfactant was added to the system. We conclude that the encapsulated GBS strain investigated needs opsonization with specific antibody to increase oxidative metabolism of PMN, and that incubation of PMN and opsonized GBS with surfactant does not interfere with NBT reduction.

Experimental neonatal group B streptococcal pneumonia: effect of a modified porcine surfactant on bacterial proliferation in ventilated near-term rabbits

We studied bacterial proliferation in relation to surfactant treatment in a model of neonatal group B streptococcal (GBS) pneumonia. Surfactant (Curosurf) was isolated from pig lungs with a method preserving only polar lipids and hydrophobic proteins. Near-term rabbit fetuses were ventilated in a body plethysmograph system. At 15 min, a suspension of GBS strain 090 Ia LD (5 mL/kg, concentration approximately 10(9)/mL) was instilled intratracheally. At 30 min, surfactant (n = 12) or sterile saline (n = 13) was administered via the airways (2.5 mL/kg). A control group (n = 12) received the same volumes of saline. After 5 h the animals were killed, and samples for blood cultures and blood gases were taken from the heart. The left lung was aseptically removed, weighed, homogenized, serially diluted, and cultured on blood agar plates. The results were expressed as mean log10 colony forming units/g lung +/- SD. Compared with animals (n = 12) killed immediately after GBS instillation (8.13 +/- 0.54), there was a significant increase in bacterial numbers in both groups ventilated for 5 h, but values for surfactant-treated animals (8.96 +/- 0.38) were lower than those for animals receiving saline (9.46 +/- 0.50; p < 0.05). After 5 h, 96% of GBS-infected animals had positive blood cultures. Light microscopic examination of the right lung of GBS-infected animals revealed inflammatory changes that tended to be less prominent in surfactant-treated rabbits. We conclude that intratracheal inoculation of near-term rabbits with GBS resulted in a significant bacterial proliferation during 5 h of ventilation and that bacterial growth was mitigated by treatment with surfactant.

Oxygen radical release by neutrophils of HIV-infected patients

Neutrophils from asymptomatic HIV-infected patients have an increased Nitroblue tetrazolium (NBT) reduction, that is an increased production of oxygen radicals. Plasma from these patients can activate normal neutrophils to an increased NBT-reduction and the neutrophil activating factor thus seems to be mainly plasma bound. Further, the patients also have increased levels of plasma malondialdehyde and thus an increased lipid peroxidation. Plasma cysteine levels are low, a sign of increased consumption of antioxidants. Treatment of the asymptomatic HIV-infected patients with N-acetylcysteine corrected the plasma cysteine levels and had some beneficial effects, but did not inhibit the increased radical production by the neutrophils.

Lymphocyte and granulocyte function in nutritionally depleted patients. The effect of 2 weeks of total parenteral nutrition

Parenteral nutrition has been reported to restore impaired immune function in nutritionally depleted patients. Lymphocyte and granulocyte function were studied before and after 2 weeks of total parenteral nutrition (TPN) in 9 depleted patients, 5 with gastrointestinal cancer and 4 with benign gastrointestinal disorders. The ability of purified blood lymphocytes to incorporate (14)C-labelled thymidine spontaneously and following mitogenic and antigenic stimulation was studied. Before TPN spontaneous lymphocyte activity was significantly increased and mitogen and antigen responsiveness significantly decreased in comparison to healthy controls. These abnormalities were more pronounced in patients with malignant disorders while the remaining patients showed a moderate impairment. No improvement in lymphocyte capacity was observed following 2 weeks of TPN. Granulocyte function measured as chemotaxis, phagocytosis, NBT-reduction and bactericidal capacity did not differ significantly between patients and controls and no changes were seen following nutritional treatment. These findings support the concept that the underlying disease and/or other factors rather than the secondary nutritional depletion are the main reasons for immune impairment. Furthermore, no immunomodulating effects of lipid emulsions on lymphocyte and granulocyte function, under these experimental conditions, were apparent.

Clinical tolerance and metabolism of a fat emulsion containing carnitine and gamma-linolenic acid

The purpose of the present study was to study the metabolism and evaluate the tolerance of a new fat emulsion, which is rich in gamma-linolenic acid and has been supplemented with carnitine. 24 adult male volunteers participated in an open, randomised, crossover study where half of the subjects were given Intralipid 20% (IL) on day one followed by administration of the supplemented fat emulsion (FE) on day two, the other half being treated in the reverse order. Both fat emulsions were first administered as a bolus dose of 0.10 g triglycerides per kg BW (an intravenous fat tolerance test) followed 40 min later by a continuous intravenous infusion during 4 h at a rate of 0.21 g triglycerides per min. The plasma fractional elimination rate, k(2)-value, was lower for FE than for IL (4.6 +/- 1.8 vs 5.3 +/- 1.6% per min, P < 0.05, mean +/- SD). Infusion of FE, as distinct from IL administration, was accompanied by a marked increase in serum gamma-linolenic acid concentration (239 +/- 133 vs 0 +/- 11 mumol/l, P < 0.05). No differences between FE and IL were discernible regarding the serum concentrations of dihomo-gamma linolenic acid (C 20: 3omega6), arachidonic acid (C 20: 4omega6), adrenic acid (C 22: 4omega6) or docosapentanaenoic acid (C 22: 5omega6). Leucocyte chemotaxis and random migration increased, 0.5 +/- 0.3 arb. units (P < 0.01) and 0.2 +/- 0.2 arb. units (P < 0.05), during infusion of FE but no such effect was noted during IL administration. No effect of the fat emulsion composition and carnitine was detected on phagocytosis and oxidative metabolism of neutrophil leucocytes. In conclusion, the new fat emulsion containing a relatively high proportion of gammalinolenic acid and supplemented with carnitine was found to be well tolerated although it was eliminated from plasma at a 13% slower rate. The supplemented fat emulsion had a moderate stimulatory effect on leukocyte chemotaxis.

The role of O-antigen polysaccharide in the activation of neutrophils by lipopolysaccharides of Salmonella species

Activation of neutrophils by lipid A, O-antigen polysaccharides (PS) and smooth lipopolysaccharides (LPS) isolated from Salmonella choleraesuis (O-6,7) and Salmonella typhimurium (O-4,5,12) was investigated. The methods used were assays for lysozyme release and for nitroblue tetrazolium (NBT) reduction which measures the level of oxidative metabolism of neutrophils. LPS from both species stimulated neutrophils to the same extent in the presence of autologous plasma. In the absence of plasma only the O-6,7 LPS activated neutrophils. Lipid A or PS isolated from both LPS either did not activate neutrophils or did so only at very high concentrations when tested in the presence of plasma; in the absence of plasma no activation occurred. The data indicate that both PS and lipid A segments of LPS are required for activation of neutrophils by LPS. We also deduce that plasma, probably complement, is required for the interaction of some LPS, e.g. O-4,5,12 with neutrophils whereas other LPS, e.g. O-6,7 can interact directly and activate neutrophils.

Alveolar macrophages and lung lesions after combined exposure to nickel, cobalt, and trivalent chromium

In earlier inhalation exposures of rabbits, nickel increased the production of surfactant by type II cells, with secondary effects on morphology and function of alveolar macrophages. Cobalt induced mainly a nodular growth pattern of the type II cells. Trivalent chromium seemed to impair the capacity of macrophages to catabolize surfactant but did not affect the type II cells. We exposed rabbits by inhalation to combinations of nickel (0.6 mg/m3 as NiCl2) and trivalent chromium [1.2 mg/m3 as Cr(NO3)3] (Ni-Cr), cobalt (0.5 mg/m3 as CoCl2) and nickel (0.5 mg/m3) (Co-Ni), or cobalt (0.5 mg/m3) and chromium (1.2 mg/m3) (Co-Cr) for 4 months, 5 days/week, 6 hr/day. Alveolar macrophages, alveolar type II cells, and lung content of phospholipids were determined. All combined exposures induced more pronounced lung lesions than exposures for each of the metals. Phospholipid concentrations were significantly higher. There were significantly higher percentages of macrophages filled with surfactant-like inclusions and a smooth surface. Accumulations of macrophages in alveoli were more widespread. Chromium potentiated the effects of nickel and cobalt on the type II cells, which led to secondary effects on the macrophages. Nickel potentiated the specific effects of cobalt, i.e., type II cell nodule formation. The result indicates that noxious effects could also be induced in man by combined exposure to nickel, cobalt, and trivalent chromium in concentrations similar to those occurring in some occupational settings.

Treatment of bacterial vaginosis with lactobacilli

60 women with bacterial vaginosis were entered into a double blind, placebo-controlled treatment trial with lyophilized Lactobacillus acidophilus. The lactobacilli used were producing H2O2. Immediately after completion of treatment, 16 out of 28 women who were treated with lactobacilli had normal vaginal wet smear results, in comparison to none of the 29 women treated with placebo. All women harboured Bacteroides at inclusion. Bacteroides was eliminated from the vagina of 12 out of 16 healthy women after treatment. Only three of the women who received the Lactobacillus suppository were free of bacterial vaginosis after the subsequent menstruation.

Effect of Brucella abortus lipopolysaccharide on oxidative metabolism and lysozyme release by human neutrophils

Both Brucella abortus lipopolysaccharide (LPS) and lipid A were low activators of nitroblue tetrazolium reduction and lysozyme release in human neutrophils. The stimulation was dose dependent and was higher in the presence of autologous plasma than in its absence. The comparison between Brucella LPS and lipid A versus Salmonella LPS revealed that at least 100 times more LPS and 1,000 times more lipid A of the former genus were required to induce significant nitroblue tetrazolium reduction and a corresponding lysozyme release in neutrophils. Low Brucella LPS-mediated superoxide and lysozyme production might contribute to the survival of these facultative intracellular bacteria in phagocytic cells.

Intralipid decreases the bacterial lipopolysaccharide induced release of oxygen radicals and lysozyme from human neutrophils

Human neutrophils were incubated either with purified cell envelope lipopolysaccharides (LPS) of salmonella or with different concentrations of LPS combined with Intralipid. Incubation of neutrophils with LPS alone increased their oxidative metabolism with increased release of oxygen radicals as measured by the nitroblue tetrazolium (NBT) test and chemiluminescence response. The amount of lysozyme released by the cells also increased during incubation with LPS. However, when the neutrophils were incubated with LPS together with Intralipid, the LPS induced stimulation of the neutrophil NBT reduction, chemiluminescence and lysozyme release was significantly decreased. Intralipid might substitute for plasma high density lipoproteins (HDL), which are known to inhibit the LPS effects on the neutrophils in the acute stage of an infection with Gram-negative bacteria.

Influence of human plasma high density lipoproteins from septic patients on different functions of normal human neutrophils

High Density Lipoproteins (HDL) from three patients with E. coli sepsis contained high, low and no Serum Amyloid Protein (Apo SAA), respectively. Preincubation of neutrophils from healthy persons for half an hour with sepsis HDL as well as normal HDL increased the phagocytosis, the stimulated nitroblue tetrazolium reduction, the chemotaxis and the random migrations of these cells. However, for all these functions, lower values were obtained after incubation with sepsis HDL containing high amounts of apo SAA than with normal HDL. A qualitative change of HDL might thus in part be responsible for the decreased function of neutrophils noted during the acute phase of bacterial infections.

Significance of oxygen availability for release of oxygen free radicals and lysozyme by neutrophils

Neutrophilic granulocytes were exposed to an atmosphere of nearly 100% oxygen (hyperoxia) for one hour. The nitroblue tetrazolium (NBT) reduction, reflecting oxygen radical release, was decreased both in resting and stimulated cells, but lysozyme release was unchanged. Short time exposure of patients to oxygen hypertension might therefore be beneficial as therapy, in conditions where reduced production of oxygen radicals is required. The NBT reduction of resting and stimulated neutrophils in an atmosphere of purified argon (hypoxia) was also considerably decreased, and the lysozyme release unchanged. This reflects the anaerobic conditions in abscesses, where the contribution of neutrophil oxygen metabolites to the killing of microorganism might be reduced.

Neutrophil leucocyte function in primary hyperparathyroidism

Neutrophil leucocyte chemotaxis, phagocytosis and oxidative metabolism were measured in six patients with primary hyperparathyroidism (HPT) who underwent parathyroidectomy. The preoperative neutrophil chemotaxis value was 6.2 +/- 0.3 arb.U. and this decreased to 5.8 +/- 0.5 arb.U. (p less than 0.05) on the third postoperative day and to 5.4 +/- 0.3 arb.U. three weeks later. Serum calcium levels were 2.95 +/- 0.06 mmol/l preoperatively and decreased to 2.20 +/- 0.05 (p less than 0.05) and 2.34 +/- 0.05 mmol/l (p less than 0.05) on the third and 21st day after parathyroidectomy. Phagocytosis measured as the intracellular uptake of complement-opsonized yeast particles by neutrophils was not influenced by operation. In a control group, six patients undergoing hemithyroid ectomy due to microfollicular tumours were studied. In this group leucocyte chemotaxis, phagocytosis and serum calcium levels were not significantly different before and after surgery. Neutrophil oxidative metabolism, measured by the ability of the cells to reduce nitroblue tetrazolium (NBT), was similar in the HPT and control groups both before and after operation. The results indicate that HPT is associated with an abnormal leucocyte migration which is reversed after successful parathyroidectomy.

Plasma clearance of intravenous fat emulsion in acute bacterial infections

A variety of abnormalities in lipid metabolism during infection have been reported and it has been questioned whether intravenous fat emulsion should be given in septic states. This study was designed to investigate the removal of a fat emulsion from plasma during septicaemia. An intravenous fat tolerance test (0.1 g of fat in the form of Intralipid 10% per kg b.w.) was performed in 28 adult patients who had been admitted for suspected septicaemia. All patients were febrile (mean body temperature 38.9 +/- 0.1 degrees C SEM), the majority had leucocytosis (mean value 10.5 +/- 1.0 10 (9)1 ) and all were haemodynamically stable. On the basis of bacterial cultures taken from various locations, the patients were classified as septic (n = 12; gram-negative sepsis, n = 8; gram-positive sepsis, n = 4), infected but without septicaemia (n = 9) or febrile of unknown cause (all cultures negative, n = 7). Plasma fractional removal rates of intravenous fat were similar in the different groups. The mean plasma clearance rate of intravenous fat was 6.6 +/- 0.5 (% minute), which does not differ from that reported for healthy controls. All patients with proven septicaemia and 5 non-septic patients were studied two weeks later when their infection had been treated and they were off antibiotic medication. The plasma clearance rate of i.v. fat was significantly lower in the recovery phase than during the acute febrile state (5.9 +/- 0.5 vs 4.2 +/- 0.4 %/min, n = 17; p < 0.05). It is concluded that clearance of intravenous fat emulsions from plasma is unimpaired in haemodynamically stable patients with septicaemia or other acute infections.