A simple method of measuring the wear of explanted acetabular component inserts.

AIMS: The determination of the volumetric polyethylene wear on explanted material requires complicated equipment, which is not available in many research institutions. Our aim in this study was to present and validate a method that only requires a set of polyetheretherketone balls and a laboratory balance to determine wear. METHODS: The insert to be measured was placed on a balance, and a ball of the appropriate diameter was inserted. The cavity remaining between the ball and insert caused by wear was filled with contrast medium and the weight of the contrast medium was recorded. The volume was calculated from the known density of the liquid. The precision, inter- and intraobserver reliability, were determined by four investigators on four days using nine inserts with specified wear (0.094 ml to 1.626 ml), and the intra-class correlation coefficient was calculated. The feasibility of using this method in routine clinical practice and the time required for measurement were tested on 84 explanted inserts by one investigator. RESULTS: In order to get the mean for all investigators and determinations, the deviation between the measured and specified wear was -0.08 ml (sd 0.12; -0.21 to 0.11). The interobserver reliability was 0.989 ml (95% confidence interval (CI) 0.964 to 0.997) and the intraobserver reliability was 0.941 for observer 1 (95% CI 0.846 to 0.985), 0.983 for observer 2 (95% CI 0.956 to 0.995), 0.939 for observer 3 (95% CI 0.855 to 0.984), and 0.934 for observer 4 (95% CI 0.790 to 0.984). The mean time required to examine the samples was two minutes (sd 2; 1 to 5). CONCLUSION: The method presented here was shown to be sufficiently precise for many settings and is a cost-effective and quick method of determining the volumetric wear of explanted acetabular components. However, the measurement of wear for scientific purposes will probably continue to involve more accurate and dedicated laboratory equipment.Cite this article: Bone Joint Res 2017;6:530-534.

Gentamicin coating of plasma chemical oxidized titanium alloy prevents implant-related osteomyelitis in rats.

Implant related infection is one of the most feared and devastating complication associated with the use of orthopaedic implant devices. Development of anti-infective surfaces is the main strategy to prevent implant contamination, biofilm formation and implant related osteomyelitis. A second concern in orthopaedics is insufficient osseointegration of uncemented implant devices. Recently, we reported on a macroporous titanium-oxide surface (bioactive TiOB) which increases osseointegration and implant fixation. To combine enhanced osseointegration and antibacterial function, the TiOB surfaces were, in addition, modified with a gentamicin coating. A rat osteomyelitis model with bilateral placement of titanium alloy implants was employed to analyse the prophylactic effect of gentamicin-sodiumdodecylsulfate (SDS) and gentamicin-tannic acid coatings in vivo. 20 rats were randomly assigned to four groups: (A) titanium alloy; PBS inoculum (negative control), (B) titanium alloy, Staphylococcus aureus inoculum (positive control), (C) bioactive TiOB with gentamicin-SDS and (D) bioactive TiOB plus gentamicin-tannic acid coating. Contamination of implants, bacterial load of bone powder and radiographic as well as histological signs of implant-related osteomyelitis were evaluated after four weeks. Gentamicin-SDS coating prevented implant contamination in 10 of 10 tibiae and gentamicin-tannic acid coating in 9 of 10 tibiae (infection prophylaxis rate 100% and 90% of cases, respectively). In Group (D) one implant showed colonisation of bacteria (swab of entry point and roll-out test positive for S. aureus). The interobserver reliability showed no difference in the histologic and radiographic osteomyelitis scores. In both gentamicin coated groups, a significant reduction of the histological osteomyelitis score (geometric mean values: C = 0.111 ± 0.023; D = 0.056 ± 0.006) compared to the positive control group (B: 0.244 ± 0.015; p < 0.05) was observed. The radiographic osteomyelitis scores confirmed these histological findings.

Development and organization of human stratum corneum after birth: electron microscopy isotropy score and immunocytochemical corneocyte labelling as epidermal maturation's markers in infancy.

BACKGROUND: There is growing evidence for the ongoing structural and functional adaptation of the skin after birth. OBJECTIVES: The aim of this study was the definition of scanning electron microscopy markers of skin maturation in different age groups (birth to adulthood). We propose a semiquantitative score to analyse the maturation of the skin surface and a complementary evaluation of the distribution of corneodesmosin and corneodesmosomes. MATERIAL AND METHODS: An electron microscopy isotropy (E.M.I.) score was performed in six age-groups to include fullterm neonates, babies, children and adults. The distribution of corneodesmosome remnants was analysed by corneodesmosin distribution with immunocytochemical corneocyte labelling. RESULTS: The E.M.I. score showed the highest anisotropy in neonates. The youngest groups displayed irregular and thick cell clusters composed of poorly individualized cells. In the older groups, the distribution of superficial corneocytes was more regular. The cells evenly covered the surface and displayed easily visualized single cell outlines. The distribution of immune-labelled corneodesmosome remnants and the corneocyte projected area showed a correlation between age and structural maturation. The observed evolution indicated a poorly controlled process of corneocyte desquamation in infants and confirmed the relative immaturity of the epidermal barrier up to 1-2 years after birth under basal conditions. CONCLUSION: Our study is the first attempt at semiquantitative evaluation of the micromorphology maturation of the epidermal surface at the ultrastructural level. The E.M.I. score and the associated pattern of corneodesmosome breakdown may be used as markers of the stratum corneum maturation.

Osteointegration of hydroxyapatite-titanium implants coated with nonglycosylated recombinant human bone morphogenetic protein-2 (BMP-2) in aged sheep.

Osteointegration of metal implants into aged organisms can be severely compromised due to reduced healing capacity of bone, lack of precursor cells for new bone formation, or osteoporosis. Here, we report on successful implant healing in a novel model of aged sheep in the presence of nonglycosylated bone morphogenetic protein 2 (BMP-2). Ewes of 8 to 12 years with significant radiologic and histologic signs of osteoporosis and adipocytic bone marrow received a cylindrical hydroxyapatite-titanium implant of 12 x 10 mm. BMP-2 has been produced as a bacterial recombinant fusion protein with maltose-binding protein and in vitro generation of mature BMP-2 by renaturation and proteolytic cleavage. A BMP-2 inhibition ELISA was developed to measure the in vitro release kinetics of bioactive human BMP-2 from immersed solid implant materials by using Escherichia coli expressed and biotinylated recombinant human BMP-2 receptor IA extracellular domain (ALK-3 ECD). The implants were placed laterally below both tibial plateaus, with the left leg implant carrying 380 microg BMP-2. Both implant types became integrated within the following 20 weeks. The control implant only integrated at the cortical bone, and little new bone formation was found within the pre-existing trabecular bone or the marrow cavity. Marrow fat tissue was partially replaced by unspecific connective tissue. In contrast, BMP-2-coated implants initiated significant new bone formation, initially in trabecular arrangements to be replaced by cortical-like bone after 20 weeks. The new bone was oriented towards the cylinder. Highly viable bone marrow appeared and filled the lacunar structures of the new bone. In mechanical tests, the BMP-2-coated implants displayed in average 50% higher stability. This animal model provided first evidence that application of nonglycosylated BMP-2 coated on solid implants may foster bone healing and regeneration even in aged-compromised individuals.

Systemic and intracerebroventricular administration of sodium barbital induced a place preference in rats.

We have shown previously that 15 mg/kg pentobarbital induces a conditioned place preference (CPP), but it is unsuitable for intracranial administration. Since the long-acting barbiturate, sodium barbital, is soluble at a neutral pH, we tested whether it would induce a CPP when administered centrally. Furthermore, because barbital has a long duration of action, and because we obtained a significant CPP to systemically administered barbital using 30-minute conditioning trials, we tested whether longer conditioning trials would produce a more robust CPP. Using a three-compartment apparatus and an unbiased procedure, we found that systemic administration of barbital induced a significant CPP at 8 and 24 mg/kg, but not 2.7 or 72 mg/kg (i.p.). When rats were conditioned to 24 mg/kg barbital for conditioning trials of (1/2), 1, 3, or 6 hours, only the 30-min conditioning trial produced a CPP. Finally, 240 and 480 microg intracerebroventricular (ICV) barbital induced a significant CPP, but 60 or 120 microg did not. These findings suggest that: (1) like pentobarbital, barbital has reinforcing properties measured in the CPP test; (2) the CPP is impaired, rather than enhanced, by increasing the duration of drug-context pairing; and (3) the reinforcing effects of barbiturates are centrally mediated.

IgE-mediated allergy to recombinant human insulin in a diabetic.

A 63-year-old nonatopic female suffering from type II diabetes with severe local and systemic immediate-type allergic reactions to injections of different recombinant human insulin products has been reported. Skin testing as well as IgE measurements not only proved immediate-type sensitization to human insulin but also to porcine and bovine insulin which had never been administered and indicated immunological cross-reactivity. Cross-reactivity was proved by an IgE inhibition test. Independent of this reaction, the patient showed IgE-mediated sensitization to protamine.

Pentobarbital-induced place preference in rats is blocked by GABA, dopamine, and opioid antagonists.

RATIONALE: Drugs that are self-administered usually produce a conditioned place preference (CPP) but pentobarbital is self-administered by both animals and humans and is reported to be aversive in the CPP test. OBJECTIVES: We tested whether pentobarbital (5, 15, and 25 mg/kg; IP) could produce a place preference and examined the role of GABA, dopamine (DA) and opioid receptors in the pentobarbital CPP. METHODS: Place conditioning was carried out in an apparatus consisting of two compartments connected by an alley at the rear. During the pre-exposure and test phase, the rats were free to wander in the apparatus for 20 min, and were drug-free. During the 6-day conditioning phase, rats were injected with drug (or vehicle), and confined to one compartment for 30 min and on alternate days were injected with vehicle (or drug) and confined to the other compartment. Upon obtaining a CPP, we examined whether pretreatment of the GABAA antagonists picrotoxin or bicuculline (0.5, 1.0, and 2.0 mg/kg; IP), the DA antagonist eticlopride (0.01, 0.05, and 0.25 mg/kg; SC), or the opioid antagonist naloxone (0.02, 0.20, and 2.0 mg/kg; IP) would block the CPP. RESULTS: 15 mg/kg pentobarbital produced a CPP. The pentobarbital CPP was blocked by pretreatment of 1.0 and 2.0 mg/kg bicuculline, but not by 0.5, 1.0, or 2.0 mg/kg picrotoxin. The pentobarbital CPP was also blocked by 0.05 and 0.25 mg/kg eticlopride and by all of the doses of naloxone tested. CONCLUSIONS: Pretreatment with the antagonists bicuculline, eticlopride, and naloxone blocked a 15 mg/kg pentobarbital CPP. This indicates that GABAergic, dopaminergic, and opioid systems play a role in the reinforcing properties of pentobarbital.

Standardization of Alternaria alternata: extraction and quantification of alt a 1 by using an mAb-based 2-site binding assay.

BACKGROUND: Alternaria alternata is recognized as an important cause of allergic disease. As with other molds, the extracts of A alternata used for diagnosis and therapy are highly heterogeneous, and there is a need for improved standardization. The major allergen Alt a 1 is well characterized and has been produced as a recombinant protein, but very few data are available on the Alt a 1 content in extracts. OBJECTIVE: An assay for the quantification of Alt a 1 was developed and used for monitoring batch-to-batch consistency of A alternata extracts, and the correlation between skin prick test responses and Alt a 1 concentrations was studied. METHODS: A 2-site binding assay based on an Alt a 1-specific mAb was developed and used for the quantification of Alt a 1 in allergen extracts. Quantitative skin prick tests were performed on 16 A alternata-sensitive patients and correlated with the Alt a 1 concentration. RESULTS: The Alt a 1-specific mAb was found to be suitable for affinity purification, as well as for a 2-site binding quantification assay. In allergen extracts the Alt a 1 content was estimated as 2% to 4.7% of total protein. Quantitative skin prick tests showed an Alt a 1 concentration-dependent response. CONCLUSION: Quantification of Alt a 1 in A alternata extracts reflects their batch-to-batch consistency. Skin prick test responses to a standardized A alternata extract correlate with the Alt a 1 contents. An extract containing 3.7 microgram/mL Alt a 1 caused a response equal to that of a 1% histamine dihydrochloride solution.

Pathways for the oxidation of sarin in urban atmospheres.

The nerve agent sarin has recently been deployed by terrorists in a major city. The molecule is volatile and made its way to many victims by passing as vapor through a highly reactive medium. Here we estimate rates and pathways for the removal of gas phase sarin from a generalized urban atmosphere. Only information from the open scientific literature is used. By structure reactivity comparisons with the organophosphorus pesticides, hydroxyl radical hydrogen abstraction may occur in as little as one hour. Decomposition of side chains after hydroxyl attack leads to organic oxygenates which preserve the phosphonofluoridate and so toxicity. The aqueous aerosol surface is contacted in minutes and offers access to a range of dissolved nucleophiles. Substitution displaces the fluoride leaving group, giving safe phosphoric acid analogs. Because of uncertainties in the electron distribution and in aqueous decay mechanisms, the time constants must be viewed as lower limits.

Particulate Air Pollution in Mexico City: A Collaborative Research Project.

PM10, PM25, precursor gas, and upper-air meteorological measurements were taken in Mexico City, Mexico, from February 23 to March 22, 1997, to understand concentrations and chemical compositions of the city's particulate matter (PM). Average 24-hr PM10 concentrations over the period of study at the core sites in the city were 75 H g/m3. The 24-hr standard of 150 µ g/m3 was exceeded for seven samples taken during the study period; the maximum 24-hr concentration measured was 542 µ g/m3. Nearly half of the PM10 was composed of fugitive dust from roadways, construction, and bare land. About 50% of the PM10 consisted of PM2.5, with higher percentages during the morning hours. Organic and black carbon constituted up to half of the PM2.5. PM concentrations were highest during the early morning and after sunset, when the mixed layers were shallow. Meteorological measurements taken during the field campaign show that on most days air was transported out of the Mexico City basin during the afternoon with little day-to-day carryover.

Serotonin and feedback effects of behavioral activity on circadian rhythms in mice.

Wheel running activity can shorten the period (tau) of circadian rhythms in rats and mice. The role of serotonin (5HT), in this effect of behavior on circadian pacemaker function, was assessed by measuring tau during wheel-open and wheel-locked conditions in mice sustaining neurotoxic 5HT lesions directed at the suprachiasmatic nucleus (SCN). Intact mice exhibited a significant lengthening of tau (approximately 10 min) within 3 weeks when running wheels were locked. Mice with immunocytochemically confirmed 5HT depletion showed significantly longer tau than intact mice during wheel access, and did not show a significant change in tau up to 6 weeks after wheels were locked. In these mice, variability of tau across wheel access conditions was similar in magnitude to tau variability in intact mice at two time points without wheel access (+/- 3 min). 5HT-depleted mice also exhibited significantly longer activity periods (alpha), and a significantly delayed peak of activity within alpha. Previous studies show that a delayed peak of activity within alpha is associated with longer tau. Group differences in tau, and apparent failure of wheel-locking to lengthen tau in mice with 5HT lesions, may thus be due to loss of a serotonergic behavioral input pathway to the SCN, or to a lesion-induced change in the waveform of the activity rhythm.

Discrimination of circadian phase in intact and suprachiasmatic nuclei-ablated rats.

This study examined whether the circadian system of rats can serve as a consulted clock for discriminating time of day. Food restricted rats housed in activity wheels were trained to lever press for food in a two-lever T-maze in which the left arm was correct in a morning feeding session, and the right arm in an afternoon session (7 h interval). All six rats learned the task (discrimination ratios > chance on 85-95% of sessions) and exhibited anticipatory wheel running prior to most sessions. Performance was not disrupted by inverting the LD cycle or by omitting 1-3 sessions, indicating that learning was not dependent on light-dark cues, alternation strategies, or physiological states associated with intermeal interval. Five of six additional rats with ablations of the suprachiasmatic nucleus light-entrainable pacemaker acquired the discrimination, indicating that time-of-day cues can be provided by another circadian pacemaker (likely food-entrainable). The results provide the first clear evidence that the circadian system in a mammal can function as a consulted clock that provides discriminative time cues for cognitive processes subserving behavioral plasticity.

[Theophylline plus salbutamol in chronic bronchial obstruction. The additive effects of combination therapy in comparison with salbutamol monotherapy]. / Theophyllin plus Salbutamol bei chronischer Bronchialobstruktion. Additive Effekte der Kombinationstherapie im Vergleich zur Salbutamol-Monotherapie.

In a placebo controlled double-blind study of 40 chronic obstructive patients, the effects of combination treatment with slow-release theophylline and salbutamol (aerosol) was compared with salbutamol monotherapy. The randomized patient groups each containing 20 patients received-for a period of 8 days in each case-2 x 350 mg slow-release theophylline and an individual number of measured doses (puffs) salbutamol aerosol per day or only the beta-sympathicomimetic aerosol and placebo capsules. Lung function measurements and a subjective assessment of the clinical status of the patients were obtained at the beginning and the end of the study. As the most important parameter of the antiobstructive effect of therapy the airway resistance (Rt) was employed. On completion of treatment Rt in the group receiving combination therapy was decreased on average from 0.52 kPa/l/s to 0.28 kPa/l/s, significantly more than in the placebo group (0.55 kPa/l/s to 0.46 kPa/l/s). In addition, more marked subjective improvement in the clinical status was observed in the patients on salbutamol and theophylline as compared with the patients on salbutamol aerosol only.

Instrument safety in explosive atmospheres.

The current "Energy Crisis" has dramatically increased our potential need for coal, the worlds most abundant fossil fuel. This will probably lead to a greater use of automation and instrumentation in the coal mining industry. The presence of methane in coal mines and in the coal itself plus the presence of coal dust, both of which can form an explosive atmosphere in air, means that the possibility of a gas or coal dust ignition must be considered when designing, purchasing and installing new equipment in this industry. In addition, many metallurgical processes involve the use of potentially explosive substances against which similar safety precautions must be taken. This paper outlines the various methods of protection currently in use and proposed for electrical instruments in explosive atmospheres, with particular emphasis on the work of the International Electrotechnical Commission.