Impact of the degradation leachate of the polyacrylonitrile-based material UP2W on the retention of Ni(II), Eu(III) and Pu(IV) by cement.

The uptake of 63Ni(II), 152Eu(III) and 242Pu(IV) by hardened cement paste (HCP, CEM I) in the degradation stage II (pH ≈ 12.5, [Ca] ≈ 0.02 M) was investigated in the presence of a degradation leachate of UP2W, a polyacrylonitrile-based (PAN) material used as a filter aid in nuclear power plants. The degradation leachate with a concentration of dissolved organic carbon of ∼40 ppm was obtained from the degradation of UP2W in portlandite-buffered solutions for ca. 1100 days. Redox conditions in the Pu systems were buffered with hydroquinone, which defines mildly reducing conditions (pe + pH ≈ 10) where Pu(IV) is the predominant oxidation state. The degradation leachate investigated in this work is moderately sorbed by cement, with distribution ratios (Rd) of (0.35 ± 0.15) m3 kg-1. These values are 30 to 100 times greater than distribution ratios previously reported for proxy ligands of PAN degradation products, i.e., glutaric acid, α-hydroxyisobutyric acid and 3-hydroxybutyric acid. The presence of the degradation leachate induces a moderate decrease in the uptake of 63Ni(II), 152Eu(III) and 242Pu(IV) by cement, as compared to the sorption in the presence of the proxy ligands. Nevertheless, retention in the presence of the degradation leachate remains high for all investigated radionuclides, with Rd(63Ni(II)) ≈ 2 m3 kg-1, Rd(152Eu(III)) ≈ 100 m3 kg-1 and Rd(242Pu(IV)) ≈ 30 m3 kg-1. These observations possibly reflect that the multiple functionalities (-COOH, -OH, amide groups) expected in the macromolecules (10-15 kDa) present in the degradation leachate, can offer further binding/chelating capabilities compared to the small organic proxy ligands with at most bidentate binding.

Solubility of Ca(II), Ni(II), Nd(III) and Pu(IV) in the presence of proxy ligands for the degradation of polyacrylonitrile in cementitious systems.

The solubility of Ca(OH)2(cr), ß-Ni(OH)2(cr), Nd(OH)3(s) and PuO2(ncr, hyd) was investigated in cement porewater solutions containing glutarate (GTA), α-hydroxyisobutarate (HIBA) and 3-hydroxybutarate (HBA). These ligands were proposed as probable degradation products of UP2W, a polyacrylonitrile-based filter aid used in nuclear power plants. Results obtained in this work are compared with reported solubility data in the presence of iso-saccharinic acid (ISA), a polyhydroxocarboxylic acid resulting from cellulose degradation. None of the investigated proxy ligands shows any significant impact on the solubility of Ca(II), Nd(III) or Pu(IV) in cement porewater solutions. Although the formation of binary complexes M-L (M = Ca(II), Nd(III), An(IV); L = GTA, HIBA, HBA) under acidic conditions is described in the literature, these organic ligands cannot outcompete hydrolysis under hyperalkaline conditions. GTA, HIBA and HBA induce a slight increase in the solubility of ß-Ni(OH)2(cr) at [L]tot = 0.1 M. This observation supports the formation of stable Ni(II)-GTA, -HIBA and -HBA complexes in hyperalkaline conditions, although the exact stoichiometry of these complexes remains unknown. The comparison of these results with solubility data in the presence of ISA confirms the stronger complexation properties of the latter ligand. Even though HIBA and HBA are carboxylic acids containing one alcohol group, this comparison shows that additional alcohol groups are required to efficiently chelate the metal ion and outcompete hydrolysis. This conclusion is supported by DFT calculations on the Pu(IV)-OH-L systems (L = GTA, HIBA and HBA), which indicate that the complexation with the proxy ligands takes places through the carboxylate group. XRD of selected solid phases after equilibration with proxy ligands at [L]tot = 0.1 M confirms that Ca(II), Ni(II), Nd(III) and Pu(IV) starting solid materials remained mostly unaltered in the course of the experiments. However, the presence of new XRD features suggests the possible formation of secondary phases. These results allow assessment of the effect of the proposed proxy ligands on the solubility of key radionuclides and metal ions in cementitious systems relevant for low and intermediate level waste, and feed into on-going sorption studies evaluating the impact of UP2W degradation products on the uptake of radionuclides by cement.

Septic bone and joint infections.

During the past few years, new information on the pathogenesis of skeletal and joint infections and the host-parasite interaction has been presented. Although this is basic research, several recent case reports have shown that experimental laboratory findings are often relevant for the practical treatment of patients. Bacteria long known as causative agents in orthopedic infections, as well as new and rare ones, challenge our skills in diagnosis and encourage new thinking in host-parasite interaction and epidemiology. Another expanding problem is increased resistance against antibiotics, which is now being observed in pneumococci causing joint infections.

The effect of cocaine on mitogen-induced lymphyocyte proliferation in pregnant women.

Cocaine use during pregnancy is associated with increased risk of sexually transmitted diseases, including syphilis and HIV. Many sociological and economic factors related to cocaine use have been shown to contribute to this increased risk. Cocaine may also affect immunological function thereby increasing risk for sexually transmitted diseases. The objective of this study was to determine if cocaine suppresses mitogen-induced lymphocyte proliferation in pregnant women. Peripheral blood mononuclear cells were obtained from 39 pregnant women. Lymphocyte proliferation was stimulated with concanavalin A (conA, 1 microg/mL). Cocaine was added at time zero to one set of cultures and at 0, 24, and 48 hr to a second set of cultures (to correct for cocaine degradation in culture). Three doses of cocaine were used: 0.1, 1 and 10 microg/mL. The cells were pulsed with 1 microCi 3H thymidine at 72 hr and harvested 19 hr after addition of the isotope. Lymphocyte proliferation, as determined by radioactivity (cpm) was assessed. Cocaine had no statistically significant effect on conA-stimulated lymphocyte proliferation when added at time = 0 or when added daily. Cocaine, in concentrations similar to those found in clinical experiments with drug users, does not suppress in vitro concanavalin A-induced lymphocyte proliferation in cells obtained from pregnant women.

Septic bone and joint infections.

Three main trends are apparent in the study of septic bone and joint infections. First, molecular microbiology has advanced our understanding of how microorganisms find structures in the joints and connective tissue on which to adhere, reproduce, and exert an infectious process. Second, modern diagnostic methods such as DNA hybridization and polymerase chain reaction are facilitating the identification of causative microbes. Finally, unusual and previously unknown causes of infection are being identified in joints and bone, often through a time-consuming search in which modern diagnostic techniques may be of valuable help.

Antibiotics in pregnancy.

Because it is known that antibiotics given to the mother may reach and affect the fetus, when prescribing antibiotics during pregnancy, one must take into consideration both maternal and fetal well-being. Therapy should be directed toward the maternal disease but also be safe for the fetus. The volume of distribution is increased during pregnancy, and dosages may need to be adjusted to accommodate this change. Because it is difficult to monitor the toxicity in the fetus, the physician must make careful choices when prescribing antibiotic treatment for the pregnant patient.

Prophylactic administration of penicillins for endocarditis does not reduce the incidence of postextraction bacteremia.

Sixty healthy patients were randomized to receive placebo, penicillin V (2 g), or amoxicillin (3 g) 1 hour before dental extraction was performed. Blood samples for microbiological investigation were collected before, during, and 10 minutes after surgery and were processed by lysis filtration under anaerobic conditions. There was no statistical difference among patients in the placebo group, the penicillin-V group, and the amoxicillin group in terms of incidence or magnitude of bacteremia due to viridans streptococci or anaerobic bacteria during extraction or 10 minutes after the procedure. The overall incidence rates of bacteremia after dental extraction were 95%, 90%, and 85%, respectively, for the three groups. For > 90% of 126 strains of viridans streptococci tested, the MICs of penicillin V and ampicillin were < or = 0.125 mg/L. The protective effect of prophylactically administered penicillins must be due to interference with crucial steps in the development of endocarditis (other than the transient bacteremia that occurs initially).

Human lactoferrin binding in clinical isolates of Staphylococcus aureus.

Human lactoferrin (HLf) is an iron-binding protein and a host-defence component at the mucosal surface. Recently, a specific receptor for HLf has been identified on a strain of Staphylococcus aureus associated with toxic shock syndrome. We have looked for the occurrence of 125I-HLf binding among 489 strains of S. aureus isolated from various clinical sources. HLf binding was common among S. aureus strains associated with furunculosis (94.3%), toxic shock syndrome (94.3%), endocarditis (83.3%) and septicaemia (82.8%) and other (nasal, vaginal or ocular) infections (96.1%) with a mean binding (in fmol) of 29.1, 21.9, 16.9, 22.2 and 29.2 respectively; the differences between mean HLf binding values of 29.1-29.2, 21.9-22.2 and 16.9 were significant. Furunculosis-associated (low-invasive or localised) isolates were high-to-moderate binders of HLf; 50% gave positive results at a threshold of greater than 31 fmol of 125I-HLf bound. In contrast, endocarditis-associated (high-invasive or systemic) isolates demonstrated low binding and did not bind 125I-HLf at the above threshold level. S. aureus recognised human or bovine Lf. However, bound 125I-HLf was more effectively inhibited in a dose-dependent manner by unlabelled bovine Lf than by homologous HLf. Binding of 125I-HLf to staphylococci was optimal with organisms grown in agar compared with those from broth cultures. The binding capacity of S. aureus was abolished when strains were grown on carbohydrate- and salt-rich agar media. HLf-binding ability of S. aureus did not correlate with fibronectin, fibrinogen, immunoglobulin G or laminin binding.

Bacillus cereus: a significant pathogen in postoperative and post-traumatic wounds on orthopaedic wards.

Over a period of 19 months, Bacillus species, most frequently B. cereus, were isolated from postoperative and post-traumatic wounds in 24 patients on orthopaedic wards in a Swedish hospital. Clinical signs of infection were found in all but 3 patients: in 9 patients, mild signs with increased secretion from the wounds; in 10 patients, moderate signs with fever and/or significant local reaction around the wounds; and in 2 patients, severe signs with necrotic infections. Bacillus spp. were isolated from one-fourth of all patients with wound complications following total hip arthroplasty. Their hospitalization was significantly prolonged, compared with a control group (p = 0.0042). Isolates of B. cereus from wounds should not be dismissed as contaminants or as non-pathogenic, but must be assessed in the light of the clinical situation.

Short-term self-treatment of travellers' diarrhoea with norfloxacin: a placebo-controlled study.

In a randomized, double blind, placebo-controlled, multicentre trial, 447 travellers to Africa, Asia or Latin America started three days treatment with norfloxacin 400 mg bd or placebo within 24 h after the onset of travellers' diarrhoea. One hundred and four subjects developed diarrhoea and of those 94 (46 in the norfloxacin group and 48 in the placebo group) could be analysed for efficacy. By the last treatment day, 34 patients in the norfloxacin and 18 in the placebo group were cured (P = 0.0001), four and three improved and five and 19, respectively, were failures. Recurrences were seen in three patients on norfloxacin and eight on placebo. The mean time to cure was 3.2 days in the norfloxacin group and 4.4 days in the placebo group (P less than 0.005). The number of loose stools was significantly lower in the norfloxacin group. Nine adverse events were reported; seven in the placebo and two in the norfloxacin group. Pre- and post-travel faecal samples were studied in 19 patients treated with norfloxacin, 21 treated with placebo and 21 untreated subjects without diarrhoea. In treated subjects, increased frequencies of Escherichia coli resistant to ampicillin, co-trimoxazole, doxycycline and chloramphenicol were found in both groups, though more frequently in the placebo one. No subject had norfloxacin resistant Esch. coli pre- and post-travel.

Crystal violet binding, cell surface properties and extracellular enzyme profiles of Staphylococcus aureus producing toxic shock syndrome toxin-1.

Staphylococcus aureus isolated from clinically diagnosed cases of toxic shock syndrome (TSS) showed susceptibility to phage types belonging to both I and III groups (90.5%). Phage typing patterns showed a wide diversity among 87 toxic shock syndrome toxin-1 (TSST-1) positive strains isolated from different non TSS clinical sources. Toxin producing strains isolated from both TSS and non TSS showed a remarkable ability to bind to crystal violet (pattern C/D, 97.2%) incorporated into brain heart infusion agar media at subinhibitory concentrations and these isolates were traced to biotype var. hominis. The cellular fatty acid compositions of TSS and non-TSS strains belonging to the three biotypes S. aureus var. hominis, S. aureus var. bovis and S. aureus var. canis did not differ. TSST-1 producing strains demonstrated a high salt aggregation test value (above 1.5) indicating a low cell surface hydrophobicity. Both TSS and non TSS strains demonstrated a high lipolytic activity. TSST-1 positive strains in general, showed significantly higher lipase activity than strains isolated from septicemia (p less than 0.0001) and superficial (p less than 0.0001) infections. The proteolytic activity is higher among TSS (median value 0.075 U/ml) than to non TSS (median value 0.045 U/ml) strains. There was no correlation with the quantity of toxin production in vitro and to the properties described.

The Tween 80 reaction does not correlate to triglyceride lipase production of Staphylococcus aureus.

This comparison of Tween 80 reaction with triglyceride lipase production comprises 357 Staphylococcus aureus strains from various clinical sources. Tween 80 is a water-soluble substrate, and thus estimates esterase activity. Lipase production was assayed using water-insoluble substrates (radiolabelled triglyceride emulsions). Only a minor proportion of Tween 80-positive strains had significant triglyceride lipase production (greater than 5 mU/10(9) bacteria). The discrepancy between the two methods was most pronounced in subgroups of samples with low frequency of lipase production, e.g. from isolates from superficial locations such as nasal mucosa and impetigo. Owing to its low specificity, the Tween 80 reaction therefore seems unsuitable as a marker for lipase activity in clinical isolates of Staphylococcus aureus.

Chronic progressive osteoblastic osteomyelitis: a new approach to treatment.

The clinical, histologic and radiographic picture in 16 cases in 15 patients with nonfistulating chronic progressive osteoblastic osteomyelitis of a long tubular bone which started in childhood is presented. All patients had severe pain at rest or weightbearing. Histology showed an increase of active osteoblasts. Low virulent bacteria were found in one-fourth of the patients. To reduce the osteoblastic activity, nonsteroidal antiinflammatory treatment was combined with surgical and antibiotic treatment. Eleven patients were pain-free at follow-up (average 47 months), 3 had reduced pain, and 1 patient did not respond to treatment.

Nephrotoxicity in isoxazolylpenicillin prophylaxis in hip surgery.

In 789 courses of antibiotic prophylaxis in hip arthroplasty surgery, either dicloxacillin (Diclocil) or cloxacillin (Ekvacillin) was used during two different time periods. The surgical methods, anesthesia, preoperative and postoperative care of the patients, and laboratory procedures were the same all the time. Changes in creatinine values were used as a method for evaluating the impact on renal function. When using dicloxacillin, a pathologic increase of creatinine was noted in 12 and 13 percent by two different calculation methods. Sixteen patients (4.2 percent) had a severe creatinine increase during the first postoperative week after dicloxacillin prophylaxis, requiring dialysis in 2 patients. Cloxacillin had only a marginal impact on renal function. Patients above aged 70 years were more vulnerable as regards renal function than younger persons, and the impairment was slightly dose related in all ages. In the dicloxacillin group, preoperative use of antiphlogistic drugs was correlated with reduced postoperative renal function.

Purification and characterization of a lipase from Staphylococcus aureus.

An extracellular lipase from Staphylococcus aureus (strain FN 37) was purified to homogeneity. A cell-free culture broth was subjected to ammonium sulphate precipitation, and the lipase was isolated from the resuspended pellet by adsorption chromatography on octyl-Sepharose. The purification was 957-fold, and the recovery of the octyl-Sepharose chromatography was about 100%. The specific activity of the purified lipase was 546 mU of lipase activity per micrograms protein. The purity of the final product was documented by SDS-polyacrylamide gel electrophoresis in which a homogeneous protein band of 43 kDa was found. In gel chromatography on Sephadex G-200 the lipase eluted as a homogeneous peak with an apparent molecular mass of 110 kDa, suggesting that the lipase may exist as an oligomer in physiological media. Analysis of the amino-acid composition revealed a predominance of polar, non-charged amino acids, with serine accounting for 24 mol% of the amino-acid residues.

Positional specificity and substrate preference of purified Staphylococcus aureus lipase.

We have studied the substrate preference and specificity, including positional specificity, of a lipase purified from Staphylococcus aureus (strain FN 37). This extracellular bacterial enzyme is relatively insensitive to product inhibition, and hydrolyzes tri-, di- and monooleoylglycerol in emulsified and micellar form at similar rates and without marked substrate preference. The lipase lacks positional specificity, and the hydrolysis of triacylglycerol proceeds rapidly to free fatty acid and glycerol without accumulation of intermediary products.

Cefuroxime prophylaxis in trochanteric hip fracture operations.

In a double-blind randomized study of antibiotic prophylaxis in trochanteric fractures operated on with a nail and plate, a 24-hour intravenous administration of cefuroxime 0.75 grams thrice daily (Group B) was compared with the previous regimen of cefuroxime for 24 hours plus 6 days of oral cephalexin (Group A). In each group, 56 (Group A) and 65 (Group B) patients could be evaluated. One deep infection occurred in Group B with growth of Staphylococcus aureus, and another 4 patients had discharge and cultures of which 2 showed S. aureus. In Group A, 6 patients had signs of an infection, and in 3 patients cultures were taken but were negative. There were no differences between the groups. We concluded that the prophylaxis time need not be longer than 3 days.

Lipolytic activity of Staphylococcus aureus strains from disseminated and localized infections.

Lipase production of 425 S. aureus strains isolated from patients with different clinical diagnoses and healthy carriers were measured by a specific method, using emulsified trioleoylglycerol substrate. Strains isolated from patients with septicemia showed significantly higher lipase activity than osteomyelitis strains (p = 0.011), impetigo strains (p = 0.002) and strains isolated from healthy relatives of patients with recurrent furunculosis (p = 0.019). Recurrent furunculosis and pyomyositis strains had significantly higher (p = 0.002 and 0.032, respectively) lipase activity than septicemia strains. S. aureus strains isolated from patients with a significant antibody response in an antilipase ELISA did not show a higher lipase activity in culture supernatants than strains from patients without a significant antibody response. The lipase activity was significantly higher in strains isolated from deep or subcutaneous infections, i.e., septicemia, pyomyositis, osteomyelitis, aerobic and anaerobic furunculosis, than in strains from superficial infections, i.e. impetigo, or from nasal mucosa.

Antibody response to whole cells and teichoic acid of Staphylococcus aureus strain E 1369 in human sera.

A whole cell Staphylococcus aureus enzyme-linked immunosorbent assay (ELISA) using the protein A-deficient strain E 1369 as antigen was compared to an ELISA with cell-wall teichoic acid, extracted from the same strain, as antigen for the detection of IgG antibodies against S. aureus in human sera. A total of 178 serum samples from 119 patients with S. aureus endocarditis, complicated and uncomplicated septicaemia, non-S. aureus endocarditis and septicaemia were investigated together with sera from 155 healthy controls. The sensitivity in diagnosing S. aureus endocarditis was better for the whole cell-ELISA (83%) as compared to the teichoic acid-ELISA (61%), and the same was true for complicated septicaemia (41% vs 29%). The whole cell ELISA was also more specific for S. aureus infections with only 3.6% false positive test values compared to 7.1% for the teichoic acid-ELISA. The differences were however, not statistically significant. None of the assays were able to distinguish between complicated and uncomplicated S. aureus septicaemia.