Measurement of airborne particle exposure during simulated tracheal intubation using various proposed aerosol containment devices during the COVID-19 pandemic.

The COVID-19 pandemic has led to the production of novel devices intended to protect airway managers during the aerosol-generating procedure of tracheal intubation. Using an in-situ simulation model, we evaluated laryngoscopist exposure of airborne particles sized 0.3 - 5.0 microns using five aerosol containment devices (aerosol box; sealed box with and without suction; vertical drape; and horizontal drape) compared with no aerosol containment device. Nebulised saline was used as the aerosol-generating model for 300 s, at which point, the devices were removed to assess particle spread. Primary outcome was the quantity and size of airborne particles measured at the level of the laryngoscopist's head at 30, 60, 120 and 300 s, as well as 360 s (60 s after device removal). Airborne particles sizes of 0.3, 0.5, 1.0, 2.5 and 5.0 microns were quantified using an electronic airborne particle counter. Compared with no device use, the sealed intubation box with suction resulted in a decrease in 0.3, 0.5, 1.0 and 2.5 micron, but not 5.0 micron, particle exposure over all time-periods (p = 0.003 for all time periods). Compared with no device use, the aerosol box showed an increase in 1.0, 2.5 and 5.0 micron airborne particle exposure at 300 s (p = 0.002, 0.008, 0.002, respectively). Compared with no device use, neither horizontal nor vertical drapes showed any difference in any particle size exposure at any time. Finally, when the patient coughed, use of the aerosol box resulted in a marked increase in airborne particle exposure compared with other devices or no device use. In conclusion, novel devices intended to protect the laryngoscopist require objective testing to ensure they are fit for purpose and do not result in increased airborne particle exposure.

Limitations of monoclonal antibodies for monitoring of fungal aerosols using Penicillium brevicompactum as a model fungus.

Molds are ubiquitous in every environment and many species have been recently associated with an increase in opportunistic infections in immunocompromised patients or the exacerbation of asthmatic episodes in allergic patients. The degree of environmental contamination with fungi thus needs to be monitored and in this study we report the development of a monoclonal antibody (mAb)-mediated enzyme-linked immunosorbent assay (ELISA) for the detection of spores of Penicillium brevicompactum in experimental model aerosols. In addition, we have investigated the influence of different parameters of air sampling and sample recovery on ELISA performance. MAbs were produced with standard hybridoma techniques and cross-reactivities were determined against spores of 53 fungal species by indirect ELISA. Standardized experimental fungal aerosols were collected with the Button Personal Inhalable Aerosol Sampler onto polycarbonate or polytetrafluoroethylene filters (PTFE) and the effects of different extraction buffers and filter agitation methods during sample processing on spore recovery and ELISA detection were investigated. Five mAbs were produced and all of them cross-reacted with several of 31 related Aspergillus, Penicillium and Eurotium species. However, cross-reactivities with 21 non-related fungi were rare. Spores were recovered in much higher numbers from polycarbonate filters (PFs) than from polytetrafluoroethylene filters. Optical densities (ODs) in ELISA were higher for spores collected into carbonate coating buffer (CCB) than phosphate-buffered saline (PBS). Filter bath sonication following filter vortexing had no positive effects on ELISA sensitivity. The cross-reactivity patterns of mAbs suggest that Aspergillus and Penicillium species share multiple antigens. Quantitative ELISA results for fungal aerosols were found to be influenced by differential sample processing and thus method standardization will be essential to maintain the comparability of immunometric monitoring results.

Comparison of mutagenic and recombinogenic effects of some adenine analogues in Saccharomyces cerevisiae D7.

2-Aminopurine, 2-amino-N6-hydroxyadenine and N6-hydroxyaminopurine were compared in suspension test with growing and non-growing cells for their mutagenic and recombinogenic (reciprocal and nonreciprocal) activities in Saccharomyces cerevisiae strain D7. Ethyl methanesulfonate was used as a positive control. No increases above spontaneous frequencies were observed when non-growing cells were treated with the base analogues although EMS induced concentration-dependent responses at all 3 genetic end-points. When growing cells were treated, HAP was recombinogenic and mutagenic and AHA was mutagenic, but only weakly recombinogenic. HAP induced comparable numbers of revertants at much lower concentrations than AHA. 2AP failed to induce any detectable response even at concentrations as high as 2400 microgram/ml.

Genotoxic properties of 2,4,7-trinitro-9-fluorenone.

The genotoxic effects of 2,4,7-trinitro-9-fluorenone (TNF) were studied in assays employing procaryotic (Salmonella typhimurium and Escherichia coli) and eucaryotic (Saccharomyces cerevisiae, mouse lymphoma L5178Y and Chinese hamster ovary) cells. The results show that TNF is a potent mutagen for procaryotes. It causes both frame-shift and base-pair substitution mutations, although frame-shift mutations were predominant. In Saccharomyces cerevisiae, this compound appeared to be too toxic to permit detection of genotoxic effects. TNF was also toxic to mouse lymphoma cells and Chinese hamster ovary cells but the toxic effects were reduced by metabolic activation. TNF induced a clear increase in sister-chromatid exchanges in CHO cells and in mutant frequency in mouse lymphoma cells both in the presence and absence of metabolic activation.

Improved functional outcome and more rapid return to normal activity following laparoscopic hernia repair.

BACKGROUND: The laparoscopic repair of inguinal hernias remains a controversial subject. Advantages in terms of reduced postoperative pain and improved functional status have been demonstrated in some studies and refuted in others. We performed a prospective study of a group of young healthy patients to measure pain levels and time to return to normal activity following totally extraperitoneal laparoscopic (TEP) hernia repair and compared these outcomes to those seen following conventional anterior repair. METHODS: A total of 151 patients were entered into a prospective nonrandomized study. Forty-eight patients underwent anterior repair; 103 underwent TEP repair. Patients were followed at 2 and 6 weeks to assess their level of function on a five-point scale. Their use of pain medication was also assessed, and total days away from work and days until return to full activity were documented. RESULTS: The open group returned to work at 11.5 days and to full activity at 26.7 days. The TEP group returned to work at 6.4 days and to full activity at 14.2 days (p < 0.001 for both data). There was no statistically significant difference in the use of pain medication. The TEP group reported better functional status at 2 weeks than the open group. At 6 weeks, this difference was no longer statistically significant. CONCLUSION: As compared to conventional open repair, TEP hernia repair offers advantages in postoperative function and an earlier return to full activity.

Outpatient laparoscopic cholecystectomy: what predicts the need for admission?

Laparoscopic cholecystectomy (LC) is commonly performed as an outpatient (OP) procedure in selected patients, either in ambulatory surgery units associated with a hospital or in freestanding facilities. To identify factors that may preclude OPLC, a retrospective analysis of all patients who underwent LC by two surgeons from August 1996 through June 1998 was performed. A total of 126 patients were divided into three groups. Group I comprised 102 patients who underwent attempted elective OPLC. Group II comprised 20 patients who underwent LC on an emergent basis. Group III comprised 5 patients who were admitted before LC. Data were gathered regarding patient demographics, preoperative diagnoses, preoperative laboratory values, length of stay after surgery, and complications. These data were analyzed using logistic regression and univariate analysis. Age >60 and American Society of Anesthesiologists (ASA) class >2 appeared to be significant predictors of admission, but when considered together, neither was significant. The diagnosis of acute cholecystitis or biliary pancreatitis was highly predictive of admission in both groups. An ASA class >2 did predict postoperative stay of more than 12 hours. These data suggest that OPLC can be performed safely in unselected patients. However, those patients with an ASA class >2 or with a diagnosis of biliary pancreatitis or acute cholecystitis are more likely to require admission or postoperative stay over 12 hours, and these criteria should be considered relative contraindications to OPLC in free-standing facilities.

The production and characterization of monoclonal antibodies to the fungus Aspergillus versicolor.

UNLABELLED: Fungal exposure measurements in indoor environments require accurate and precise monitoring methods. Such techniques may be based on monoclonal antibodies (Mabs) and enzyme-linked immunosorbent assays (ELISA) and here we report the cross-reactivity patterns of Mabs produced against Aspergillus versicolor. Balb/c mice were immunized with the particulate fraction of homogenized spores and 46 Mabs (35 IgM, nine IgG3, two IgG1) were produced and tested for cross-reactivity against 55 fungal species. None of the Mabs was found to be species-specific for A. versicolor. Several Mabs strongly cross-reacted with most Aspergillus, Penicillium and Eurotium species and some Mabs also cross-reacted with Paecilomyces variotii and several Cladosporium and Stachybotrys species. Our results show that antibody responses in mice against spores of A. versicolor are dominated by highly cross-reactive antibodies of the IgM isotype. The widespread cross-reactivity suggests that the specificity of antibodies to be used for the detection of fungi in environmental samples need to be thoroughly characterized in order to avoid ambiguities in the interpretation of monitoring results. Furthermore, accurate estimates of spore concentrations may require the application of species-specific Mabs in order to avoid bias in result interpretation because of the differential reactivity of cross-reactive Mabs with different fungi. PRACTICAL IMPLICATIONS: Producers of monoclonal or polyclonal antibodies for the detection of fungi in environmental or clinical samples need to verify antibody reactivity patterns and accurately report that information to potential users. Furthermore, immunoassays based on mouse or human serum or purified immunoglobulin fractions need to consider antibody cross-reactivity as a potential confounding factor during interpretation of results.

Effect of the Shuttle contaminant environment on a sensitive infrared telescope.

A sensitive ir telescope on the Space Shuttle Orbiter will be limited in its performance by fluctuations in the ir radiation from the natural environment and the contaminant atmosphere. Models of the Orbiter's contaminant atmosphere were used to predict its spectral radiance from 3 microm to 300 microm. At 350 km, statistical fluctuations in the radiation from a water vapor column density of 10(12) cm(-2) produce a noise equivalent power of about 2 x 10(-17) W/Hz(1/2) in a 1 min of arc field of view of a 1-m diameter telescope with a 10-microm spectral bandwidth. This noise is somewhat smaller than the expected contribution from zodiacal light from 5 microm to 30 microm. The column density of all ir emitting molecules can be kept as low as 10(12) cm(-2) only if restrictions on rocket firings and liquid vents are maintained. The relatively low frequency of particle sightings from Skylab, coupled with improvements in Orbiter venting techniques, indicates that sightings of particles 2 microm and larger in radius will not seriously hamper tele cope performance provided that liquid vents and rocket firings are properly restricted.

Fatigue fracture of bone plates.

Of all the possible causes of bone plate failure, by far the most common is failure by fatigue. The effect of the environment and loading regime on the fatigue life is discussed. The use of the corrosion potential for the evaluation of fatigue experiments and the detection of fatigue cracks in explanted plates is described. The authors demonstrate that the surface finish and the possibility of a loss in fatigue strength after plate remodelling are factors that should not be ignored when testing bone plates.

Oral adhesions associated with cleft lip and palate and lip fistulae.

Three cases of congenital strand-like adhesions between the upper and lower gum pads associated with cleft lip and palate and lower lip fistulae are reported. A consideration of the literature would suggest that this may represent an autosomal dominant trait with variable penetrance and expressivity though a positive family history was found in only one case. The adhesions may have arisen by persistence of the oropharyngeal membrane or anomalous fusion of adjacent epithelial surfaces, the latter seeming rather more likely in the present series. The clinical implications are discussed.

Crevice and fretting corrosion of stainless-steel plates and screws.

Mechanisms of corrosion at the areas of contact between screw heads and plate holes were investigated using electrochemical potential recording techniques. Static crevice corrosion was studied with plates and screws in isotonic and hypertonic saline solutions (0.9 to 7.2% NaCl). Fretting corrosion was studied in vitro with plates screwed to tubular bone analogs which were subjected ty cyclic axial loads, and was studied in vivo with plates screwed on the tibia of sheep. Static tests showed that crevice corrosion does not occur in isotonic saline for periods up to one year, but can occur in hypertonic saline solutions. Dynamic loading tests demonstrated immediate potential changes which were related to the magnitude of the applied load, indicating fretting corrosion due to motion between screw head and plate, both in vitro and in vivo. A mechanism for screw-plate relative motion is proposed. It is hypothesized that corrosion seen in clinically retrieved implants is due to fretting corrosion which predisposes the contact area to crevice corrosion attack.

Mutagenicity of tetramic mycotoxin cyclopiazonic acid.

Cyclopiazonic acid was shown to be mutagenic to Salmonella typhimurium TA98 and TA100 in the presence of metabolic activation. The activity of cyclopiazonic acid in the presence of aflatoxin B1 was studied in complete factorial experiments with strain TA98. Both mycotoxins produced significant mutagenic activity and in combination. The activity in combination appeared to be additive rather than synergistic. The specific activity of cyclopiazonic acid was estimated to be approximately 140 revertants per mu mol in strain TA98.

Management of biliary strictures due to laparoscopic cholecystectomy.

Injury to the extrahepatic bile ducts during laparoscopic cholecystectomy (LC) is a cause of serious long-term patient morbidity. In order to identify management strategies and outcome, we undertook a retrospective review and analysis of patients referred to the Department of Surgery and the Division of Gastroenterology for management of bile duct strictures due to injury at LC. Eighteen patients (15 women, 3 men) with a mean age of 41 years were identified over a 4-year period. Six patients had injuries identified at LC. Ten patients had previously undergone an attempt at operative repair (8 end-to-end anastomoses, 1 choledochoduodenostomy, 1 cystic duct jejunostomy). There were 5 Bismuth Grade I strictures, 6 Grade II, 2 Grade III and 5 Grade IV. Ten patients were managed nonoperatively with stents placed by radiologic or endoscopic techniques. Four patients were managed with operation alone (2 choledochojejunostomy, 1 hepaticojejunostomy, and 1 external T-tube drainage) and 4 patients with a combined endoscopic and operative approach (all 4 with hepaticojejunostomy after initial endoscopic retrograde cholangiopancreatography or percutaneous transhepatic cholangiography management). Bile duct strictures due to LC are frequently located in the proximal bile ducts (Bismuth II-IV) and are technically difficult to repair. In the majority of cases, injuries are unrecognized at LC. Both immediate and delayed repair attempts prior to referral were frequently unsuccessful. Many bile duct strictures can be managed successfully in the early postoperative period with endoscopic and radiologic stenting techniques. Strictures which cannot be managed nonoperatively are repaired with Roux-en-Y hepaticojejunostomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Aflatoxin in respirable corn dust particles.

Samples of airborne grain dust representing a variety of grains were examined for the presence of aflatoxins. Although aflatoxins could not be detected in most of the samples, one corn sample contained 130 ppb aflatoxin B1. When the components of this sample were separated according to aerodynamic diameter and analyzed for aflatoxins, it was found that particles with diameters 7-11 micrometers and less than 7 micrometers had much higher levels of aflatoxins than the sample as a whole. These findings suggest that measurements of aflatoxin in whole corn might underestimate aflatoxin levels in corn dust aerosols.

Studies of the mutagenic response of Salmonella typhimurium TA98 to size-fractionated air particles: comparison of the fluctuation and plate incorporation tests.

The high-volume Andersen sampler was used to study the mutagenic activity of size-fractionated airborne particles from ambient air in Morgantown, West Virginia. Mutagenicity was studied by the Ames Salmonella assay and the bacterial fluctuation test and was dependent on particle size in both systems, ie, the greatest activity was associated with the smallest particles. Comparison of the two systems was based on identical aliquots of each extract, cells prepared under identical conditions at the same time, and on mutagenic response at a predetermined level of statistical significance (P less than 0.05). The results suggest a slight advantage in sensitivity for the Ames test for the air samples under study.

Influence of surface treatments developed for oral implants on the physical and biological properties of titanium. (I) Surface characterization.

We present an investigation of the physico-chemical surface properties of commercially pure titanium coverslips which were submitted to various treatments designed to optimize their topography in view of application in oral implantology. The surface microroughness, chemical composition and water wettability were analyzed on titanium coverslips prepared by mechanical polishing, acid attack in HCl/H2SO4, after mechanical polishing or sandblasting, and titanium plasma-spray. The chemical composition has been measured by Auger electron spectroscopy. The treatments have no major influence on the surface chemical composition and all the samples display a composition approaching that of TiO2 with minor amounts of carbon, sulfur, silicon and calcium as impurities. The roughness has been measured by scanning force microscopy on an area of 20 microns x 20 microns on each sample. Polished titanium is smooth (peak-to-valley roughness 81 nm), whereas the acid-attacked surfaces exhibit a micro-roughness in the microns range (2100 nm for polished and acid attacked; 3600 nm for sandblasted and acid attacked) which is quite reproducible over large areas of the sample. The acid attacked samples present a subsurface layer which contains hydrogen below the native passivating oxide layer. Water wettability measurement shows that all surfaces are hydrophobic with a slightly higher contact angle for the acid attacked surfaces. The different treatments analyzed in this study essentially influence the surface roughness by preserving the chemical composition and the wettability properties of titanium native oxide surface layer.

Inhibition of cyclooxygenase by indomethacin modulates osteoblast response to titanium surface roughness in a time-dependent manner.

Prostaglandin E2 (PGE2) and transforming growth factor-beta 1 (TGF-beta 1) production are increased in cultures of osteoblasts grown on rough surfaces and prostaglandins are involved in osteoblast response to surface roughness. In the present study, we examined the effect of inhibiting cyclooxygenase on this response. MG63 osteoblast-like cells were cultured on cpTi disks with Ra values of 0.60 micron (PT), 3.97 microns (SLA), and 5.21 microns (TPS) in the presence or absence of 10(-7) M indomethacin. Treatment was begun on days 1, 2, 3, or 4 after seeding, and all cultures were harvested on day 5. Indomethacin decreased PGE2 release by the cells to less than 50% of basal levels when the cells were cultured on plastic. Cell number decreased with increasing surface roughness and indomethacin treatment abrogated the surface roughness effect over time. Alkaline phosphatase specific activity (ALP) increased with surface roughness; after one day with indomethacin, ALP was decreased on smooth surfaces, but increased on rough surfaces. Over time, ALP decreased on all surfaces examined and remained greater than plastic only in cultures on TPS. Indomethacin also caused a time-dependent decrease in osteocalcin production on rough surfaces, eventually abrogating the increases due to surface roughness, but had no effect on osteocalcin production on smooth surfaces. TGF-beta 1 levels in the cell layer and media were sensitive to surface roughness; on rougher surfaces, TGF-beta 1 shifted from the media to the matrix. Indomethacin reduced TGF-beta 1 levels over time, but the surface roughness effect was still evident at 4 days. This indicates that prostaglandin production mediates the effects of surface roughness, since indomethacin causes a time-dependent abrogation of the response, but has no effect on proliferation, osteocalcin release, or TGF-beta 1 levels on smooth surfaces. Indomethacin's effect was not immediate, suggesting that clinical protocols could be designed that would reduce inflammation without preventing osteoblastic differentiation. The effect of indomethacin was not complete, since TGF-beta 1 and ALP remained elevated on rough surfaces, suggesting that pathways or factors other than prostanoids are involved. TGF-beta 1 is preferentially stored in the matrix, acting on the cells through autocrine signaling, and may contribute to ALP even in the presence of indomethacin. These results demonstrate the importance of local factors in the autocrine regulation of osteogenesis and the potential for factors released in response to surface morphology to act in a paracrine manner.