Prediction of temperature-dependent nucleation and growth rates from crystallization-related heat release

We propose a method for determining the time and, therefore, temperature-dependent relative nucleation and growth rates during crystallization. We do so by linking the partial differential equation governing the time dynamics of the crystal size distribution to kinetic (Avrami) parameters describing heat release. This approach is tested in silico by nucleating and growing diffusion limited aggregates with time-varying morphology and growth rates unhindered by impingement. The associated heat release is analyzed, showing that nucleation and growth rates could be extracted with high fidelity.

Fast and ultrafast thermal contrast amplification of gold nanoparticle-based immunoassays

For highly sensitive point-of-care (POC) diagnostics, we explored the limit of thermal contrast amplification (TCA) reading of gold nanoparticles (GNPs/mm²) at test regions in immunoassays. More specifically, we built and compared fast (minute scale) and ultrafast (seconds scale) TCA setups using continuous-wave (CW) and ms pulsed lasers, respectively. TCA improved the limit of detection (LoD) for silica-core gold nanoshells (GNSs) preloaded in nitrocellulose (NC) membrane as model lateral flow immunoassays (LFAs) by 10- to 20-fold over visual reading. While the ultrafast TCA led to higher thermal signals, this came with a twofold loss in LoD vs. fast TCA primarily due to noise within the infrared sensor and a necessity to limit power to avoid burning. To allow higher laser power, and therefore amplification fold, we also explored transparent glass coverslip substrate as a model microfluidic immunoassay (MIA). We found the ultrafast TCA reading of GNS-coated coverslips achieved a maximal signal amplification (57-fold) over visual reading of model LFAs. Therefore, ultrafast TCA-MIA is promising for ultrasensitive and ultrafast diagnostics. Further advantages of using TCA in MIA vs. LFA could include lower sample volume, multiplexed tests, higher throughput, and fast reading. In summary, TCA technology is able to enhance the sensitivity and speed of reading GNPs (GNPs/mm²) within both LFAs and MIAs.

Ultra-Rapid Laser Calorimetry for the Assessment of Crystallization in Low-Concentration Cryoprotectants

Cryoprotective agents (CPAs) are routinely used to vitrify, attain an amorphous glass state void of crystallization, and thereby cryopreserve biomaterials. Two vital characteristics of a CPA-loaded system are the critical cooling and warming rates (CCR and CWR), the temperature rates needed to achieve and return from a vitrified state, respectively. Due to the toxicity associated with CPAs, it is often desirable to use the lowest concentrations possible, driving up CWR and making it increasingly difficult to measure. This paper describes a novel method for assessing CWR between the 0.4 × 10⁵ and 10⁷ °C/min in microliter CPA-loaded droplet systems with a new ultrarapid laser calorimetric approach. Cooling was achieved by direct quenching in liquid nitrogen, while warming was achieved by the irradiation of plasmonic gold nanoparticle-loaded vitrified droplets by a high-power 1064 nm millisecond pulsed laser. We assume "apparent" vitrification is achieved provided ice is not visually apparent (i.e., opacity) upon imaging with a camera (CCR) during cooling or highspeed camera (CWR) during warming. Using this approach, we were able to investigate CWRs in single CPA systems such as propylene glycol (PG), glycerol, and Trehalose in water, as well as mixtures of glycerol-trehalose-water and propylene glycol-trehalose-water CPA at low concentrations (20-40 wt %). Further, a phenomenological model for determining the CCRs and CWRs of CPAs was developed which allowed for predictions of CCR or CWR of single component CPA and mixtures (within and outside of the regime their constituents were measured in), providing an avenue for optimizing CCR and CWR and perhaps future CPA cocktail discovery.

Kinetics of nonisothermal phase change with arbitrary temperature-time history and initial transformed phase distributions

This paper describes the extension of the classic Avrami equation to nonisothermal systems with arbitrary temperature-time history and arbitrary initial distributions of transformed phase. We start by showing that through examination of phase change in Fourier space, we can decouple the nucleation rate, growth rate, and transformed fraction, leading to the derivation of a nonlinear differential equation relating these three properties. We then consider a population balance partial differential equation (PDE) on the phase size distribution and solve it analytically. Then, by relating this PDE solution to the transformed fraction of phase, we are able to derive initial conditions to the differential equation relating nucleation rate, growth rate, and transformed fraction.

Conduction Cooling and Plasmonic Heating Dramatically Increase Droplet Vitrification Volumes for Cell Cryopreservation

Droplet vitrification has emerged as a promising ice-free cryopreservation approach to provide a supply chain for off-the-shelf cell products in cell therapy and regenerative medicine applications. Translation of this approach requires the use of low concentration (i.e., low toxicity) permeable cryoprotectant agents (CPA) and high post cryopreservation viability (>90%), thereby demanding fast cooling and warming rates. Unfortunately, with traditional approaches using convective heat transfer, the droplet volumes that can be successfully vitrified and rewarmed are impractically small (i.e., 180 picoliter) for <2.5 m permeable CPA. Herein, a novel approach to achieve 90-95% viability in micro-liter size droplets with 2 m permeable CPA, is presented. Droplets with plasmonic gold nanorods (GNRs) are printed onto a cryogenic copper substrate for improved cooling rates via conduction, while plasmonic laser heating yields >400-fold improvement in warming rates over traditional convective approach. High viability cryopreservation is then demonstrated in a model cell line (human dermal fibroblasts) and an important regenerative medicine cell line (human umbilical cord blood stem cells). This approach opens a new paradigm for cryopreservation and rewarming of dramatically larger volume droplets at lower CPA concentration for cell therapy and other regenerative medicine applications.

Improved Influenza Diagnostics through Thermal Contrast Amplification

Influenza poses a serious health threat and creates an economic burden for people around the world. The accurate diagnosis of influenza is critical to the timely clinical treatment of patients and the control of outbreaks to protect public health. Commercially available rapid influenza diagnostic tests (RIDTs) that are operated by visual readout are widely used in clinics to screen influenza infections, but RIDTs suffer from imperfect analytical sensitivity, especially when the virus concentration in the sample is low. Fortunately, the sensitivity can be simply improved through an add-on signal amplification step, i.e., thermal contrast amplification (TCA). To demonstrate the advantage of TCA for influenza diagnosis, we conducted a prospective cohort study on 345 clinical specimens collected for influenza A and B testing during the 2017-2018 influenza season. All samples were tested using the Quidel QuickVue Influenza A + B test, followed by a TCA readout, and then confirmatory polymerase chain reaction testing. Through the TCA detecting sub-visual weak positives, TCA reading improved the overall influenza sensitivity by 53% for influenza A and 33% for influenza B over the visual RIDTs readings. Even though the specificity was compromised slightly by the TCA protocol (relative decrease of 0.09% for influenza A and 0.01% for influenza B), the overall performance was still better than that achieved by visual readout based on comparison of their plots in receiver operating characteristic space and F1 scores (relative increase of 14.5% for influenza A and 12.5% for influenza B). Performing a TCA readout on wet RIDTs also improved the overall TCA performance (relative increase in F1 score of 48%). Overall, the TCA method is a simple and promising way to improve the diagnostic performance of commercial RIDTs for infectious diseases, especially in the case of specimens with low target analytes.

Cryopreservation and Laser Nanowarming of Zebrafish Embryos Followed by Hatching and Spawning

This study shows for the first time the ability to rewarm cryopreserved zebrafish embryos that grow into adult fish capable of breeding normally. The protocol employs a single injection of cryoprotective agents (CPAs) and gold nanorods (GNRs) into the yolk and immersion in a precooling bath to dehydrate the perivitelline space. Then embryos are encapsulated within CPA and GNR droplets, plunged into liquid nitrogen, cryogenically stabilized, and rewarmed by a laser pulse. Postlaser nanowarming, embryos (n = 282) exhibit intact structure by 1 h (40%), continued development after 3 h (22%), movement after 24 h (11%), hatching after 48 h (9%), and swimming after Day 5 (3%). Finally, from fish that survives till Day 5, two larvae are grown to adulthood and spawned, yielding survival comparable to an unfrozen control. Future efforts will focus on improving the survival to adulthood and developing methods to cryopreserve large numbers of embryos for research, aquaculture, and biodiversity preservation.

Correction: Photothermal conversion of gold nanoparticles for uniform pulsed laser warming of vitrified biomaterials

Correction for 'Photothermal conversion of gold nanoparticles for uniform pulsed laser warming of vitrified biomaterials' by Yilin Liu et al., Nanoscale, 2020, 12, 12346-12356, DOI: 10.1039/D0NR01614D.

Photothermal conversion of gold nanoparticles for uniform pulsed laser warming of vitrified biomaterials

Pulsed laser (ms, 1064 nm) gold nanoparticle (GNP) heating has been used recently to achieve fast (>10 000 000 °C min^-1) warming of vitrified droplets using gold nanorods (GNRs) as photon-absorbers. To maximize the viability of biomaterials in vitrified droplets, the droplets must be warmed as uniformly as possible. A potential approach to such warming is to use an appropriate combination of photon-absorption and -scattering to distribute heat more uniformly throughout a droplet. To investigate this, 2 plasmonic gold nanorods (GNRs), 1 hollow gold nanoshell, and 2 silica-core gold nanoshells (GNSs) were synthesized and characterized under 1064 nm laser irradiation in water, propylene glycol, and protein-rich (egg white) solutions. Using a modified cuvette laser calorimetry experiment with complementary Monte Carlo modeling, the GNSs were found to have higher per-particle absorption and scattering cross sections, while the GNRs had higher photothermal conversion efficiency, absorption efficiency, and Au mass normalized absorption cross sections. In the characterization, the GNSs with larger scattering-to-absorption ratios could have ∼30% over-estimation of photothermal conversion efficiency if scattering and reabsorption inside the solution were not considered, while GNRs with lower ratios were less impacted. Combined Monte Carlo and COMSOL simulations were used to predict the specific absorption rate (W m^-3) and heating behavior of GNP-loaded hemispherical droplets, thereby demonstrating that the GNS case with higher scattering-to-absorption ratio achieved more uniform heating than the GNR case. Interestingly, further tuning of the scattering and absorption coefficients of the hemispherical GNP-loaded droplet within the model suggests the ability to obtain an optimal scattering-to-absorption ratio for uniform heating. These results show the importance of considering the reabsorption of scattered light to accurately characterize the photothermal conversion efficiency of GNP solutions during laser irradiation. We also show that the relative scattering and absorption properties of the nanoparticles can be designed to promote both rapid and uniform laser rewarming of vitrified droplets for application in cryopreservation.

Functional outcome of total knee replacement: a study protocol for a prospective, double-blinded, parallel-group randomized, clinical controlled trial of novel, personalized and conventional implants

BACKGROUND

The development of total knee replacement (TKR) implant designs aims to improve outcome regarding pain, function, joint stiffness, instability, patellar problems, and ultimately wear of the implant. Recently, two major orthopaedic implant manufacturers launched a new generation of TKR implants which, according to the manufacturers, provide improved functional outcome. However, the benefits of these new TKR designs claimed by the manufacturers in terms of improved functional outcome still lack scientific documentation. The present randomized controlled trial has been designed to compare three fixed bearing, cemented cruciate-retaining (CR) designs; one of the new personalized TKR design with two conventional TKR designs with the main emphasis being on functional outcome.

METHODS

The present study is a prospective, double-blinded, randomized, single-center intervention trial. A total of 240 patients will be recruited to participate in a parallel-group study at Coxa Hospital for Joint Replacement, Tampere, Finland. We will compare the short-term functional outcome of TKR performed with a novel personalized TKR design (Persona CR, Zimmer, Warsaw, IN, USA) against TKRs performed with two conventional designs (PFC CR, DePuy, Warsaw, IN, USA and Nexgen CR, Zimmer, Warsaw, IN, USA). In total, 80 patients will be randomized in each of the three study arms. The primary outcome in this study is the Oxford Knee Score (OKS), which is a validated patient-reported outcome measure (PROM). Secondary outcome measures include the Forgotten Joint Score, the 15D, the UCLA activity score, and the VAS pain scale. The results will be analyzed after 2-year follow-up.

DISCUSSION

This paper presents a prospective, randomized, single-center trial study protocol. It provides details of patient randomization, PROMs, follow-up, methods of analysis of the material, and publication plan. An important aspect that will be considered in the study will be the economic effects of the novel designs as they are substantially more expensive, and the benefits of the added costs remain unknown. In addition, it is especially important to carry out evaluative studies in independent centers that are not biased by the interests of the manufacturers.

TRIAL REGISTRATION

Retrospectively registered, November, 2017, ClinicalTrials.gov Identifier: NCT03339557 .

Histomorphometric Analysis of Poly-L/D-Lactide 96/4 Sutures in the Gastrocnemius Tendon of Rabbits

Background

Common Achilles tendon ruptures are not usually fixed by bioabsorbable sutures due to limitations in their strength retention properties. Modern technology has made it possible to develop bioabsorbable sutures with prolonged strength retention.

Aims

To evaluate histologically tissue reactions of poly-L/D-lactide (PLDLA) sutures implanted in Achilles tendon of rabbits.

Material and Methods

Fifteen rabbits were evaluated at 2, 6 and 12 weeks postoperatively, with five rabbits in each follow-up group. PLDLA monofilament sutures were implanted into the medial gastrocnemius tendon. Polyglyconate monofilament sutures with similar diameter (Maxon® 4–0, Cyanamid of Great Britain Ltd., Gosport, UK) were implanted in the contralateral gastrocnemius tendon. The histology was studied in hard-resin embedded samples. The thickness of the formed fibrous tissue capsule was determined histomorphometrically.

Results

PLDLA led to formation of significantly thinner fibrous tissue capsule than Maxon® sutures of the same diameter. Median thickness (PLDLA vs. Maxon®) at two weeks was 5.26 vs. 13.22μm, at six weeks 11.66 vs. 80.97μm, and at 12 weeks 10.63 vs. 17.59μm (p<0.01).

Conclusions

During the 12 week follow-up period, PLDLA sutures implanted intratendineously formed thinner fibrous capsule than Maxon® sutures of the same diameter. The suture materials were not totally absorbed by 12 weeks.

Empirical study on voting power in participatory forest planning

Multicriteria decision support systems are applied in natural resource management in order to clarify the planning process for the stakeholders, to make all available information usable and all objectives manageable. Especially when the public is involved in planning, the decision support system should be easy to comprehend, transparent and fair. Social choice theory has recently been applied to group decision-making in natural resources management to accomplish these objectives. Although voting forms the basis of democracy, and is usually taken as a fair method, the influence of voters over the outcome may vary. It is also possible to vote strategically to improve the results from each stakeholder's point of view. This study examines the use of social choice theory in revealing stakeholders' preferences in participatory forest planning, and the influence of different voters on the outcome. The positional voting rules examined were approval voting and Borda count, but both rules were slightly modified for the purposes of this study. The third rule examined, cumulative rule, resembles utilitarian voting rules. The voting rules were tested in a real participatory forest planning situation in eastern Lapland, Finland. All voting rules resulted in a different joint order of importance of the criteria. Yet, the preference orders produced had also a lot in common and the criteria could be divided into three quite distinct groups according to their importance. The influence of individual voters varied between the voting rules, and in each case different voter was the most influential.

Determination of gallic acid in wood dust as an indicator of oak content

A high-performance liquid chromatography (HPLC) method was developed for the detection of extracted gallic acid in wood dust. Gallic acid is a polyphenol present in carcinogenic oak wood dust, but not in beech, ash, pine or spruce dusts, as confirmed by HPLC analyses. The method involved the extraction of gallic acid from the oak dust, followed by liquid chromatographic analysis. The correlation coefficient for the share of oak dust vs. the gallic acid concentration of wood dust was 0.995. The method was tested with oak wood dust samples collected on polycarbonate membrane filters during an 8 h workshift in a floor board factory, where the dust content of the air samples was determined gravimetrically. The oak dust and the gallic acid concentrations varied from 0.2 to 13.8 mg m-3 and from 0.03 to 3.8 micrograms m-3, respectively. These parameters were linearly correlated with a correlation coefficient of 0.95. The airborne gallic acid determination is a useful technique to confirm occupational exposure to oak wood dust, a recognized human carcinogen.

Mutations induced by 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) in cecum and proximal and distal colon of lacI transgenic rats

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a food-borne mutagen and carcinogen that induces tumors of the colon and the prostate gland in male rats and of the mammary gland in female rats. In this study we describe the frequency and specificity of PhIP-induced mutations in the cecum, proximal colon and distal colon of male and female lacI transgenic rats. This is the first report of mutational data from discrete regions of the colon. After 61 days of treatment with 200 p.p.m. PhIP mixed into the diet, PhIP-induced mutant frequencies were elevated 7-fold in the cecum and 14- to 21-fold in the colon of male and female rats compared with untreated controls. PhIP-induced mutant frequencies increased significantly (overall trend, P < 10(-4)) along the length of the colon of both males and females, with cecum < proximal colon < distal colon. A total of 754 PhIP mutants (363 male, 391 female) were sequenced to provide the mutational spectra for each of the three tissue sections from males and females. These mutational spectra consisted predominantly of G:C-->T:A and G:C-->C:G transversions and deletions of G:C base pairs. There were no significant differences between the mutational spectra with respect to sex or position in the colon. Therefore, we surmise that following induction of mutations by PhIP in male and female colons, non-mutagenic factors, possibly hormonal, preferentially influence the formation of tumors in the colon of male rats.

Comparison of strength properties of poly-L/D-lactide (PLDLA) 96/4 and polyglyconate (Maxon) sutures: in vitro, in the subcutis, and in the achilles tendon of rabbits

Achilles tendon rupture is a common injury. Absorbable sutures are not commonly used because of their limited strength properties. Recently, sutures with prolonged strength retention properties have been developed. The aim of the study is to test the mechanical properties of recently developed poly-L/D-lactide (PLDLA) sutures in comparison with polyglyconate (Maxon) sutures. PLDLA (0.2 mm thick) and Maxon (4.0) sutures were studied in vitro by immersion in a buffered saline solution (pH 7.4). Tensile strength tests were done on sutures retrieved after 1-26 weeks. In vivo, they were implanted in the subcutis of 32 rabbits. Tensile strength tests were done on sutures retrieved after 1-6 weeks. The sutures were also used to repair the Achilles tendon in rabbits. Maximum force before breaking and percentage elongation of tendons were determined. Although PLDLA had a lower initial tensile strength than Maxon, PLDLA showed more prolonged tensile strength retention than Maxon. Tendons repaired with PLDLA, however, had a lower strength than Maxon-repaired tendons at six weeks (insignificant difference). PLDLA has more prolonged tensile strength properties compared with Maxon. Thus, PLDLA offers an alternative to Maxon in repair of the Achilles tendon.

Effect of in situ composting on reducing offensive odors and volatile organic compounds in swineries

Seven swine farms were studied to find out how the in situ composting system, compared to the slatted floor pit system, influences the concentration and occurrence of malodorous compounds. Ammonia concentrations were measured with diffusion tubes. Small molecular sulfur compounds were analyzed using laminated bags and a gas chromatograph with a FP-detector. All other volatile organic compounds were analyzed by gas chromatography/mass spectrometry with simultaneous sniffing of the eluted compounds. About 400 organic compounds were identified from the air samples, and 94 suspect odorous compounds are listed in the present article. The most intense and unpleasant odors were caused by p-cresol, carboxylic acids (C2-C7), and some ketones such as 3-hydroxy-2-butanone, 2,3-butanedione, and 2-butanone. Terpenes (alpha-pinene, beta-pinene, 3-carene, and limonene), which originate from sawdust, caused the main peaks in the chromatograms of compost swineries. In swine confinement buildings where the composting system was functioning properly, the concentration of sulfur compounds, and especially of carboxylic acids, ketones, and p-cresol, fell effectively. The use of sawdust as composting material caused elevated concentrations of terpenes in the ambient air. There was clearly less airborne ammonia and hydrogen sulfide in the well-functioning compost swineries than in the poorly functioning ones. Elevated hydrogen sulfide levels were measured during turning work, however. In one composting swinery, the hydrogen sulfide level was as high as 15 mg/m3 during turning work. All the other concentrations of odorous compounds did not exceed occupational exposure limit values, but several compounds exceeded the respective threshold odor concentrations.

Evaluation of exposure to airborne bacterial endotoxins and peptidoglycans in selected work environments

The aim of this study was to assess workers' exposure to endotoxins and peptidoglycans, as well as associations between workers' reported symptoms and the detected bacterial exposures. From the filter samples, biologically-active endotoxins were analysed with the Limulus amebocyte lysate (LAL) assay. The total amount of endotoxins was analysed as 3-hydroxy (OH) fatty acids with a gas chromatography-mass spectrometry (GC-MS) assay, which was also used to assess peptidoglycans as muramic acid. Biologically-active endotoxins related better to the self-reported symptoms than total endotoxins. Specific 3-OH-14:0 fatty acid in the total endotoxin samples associated better with the symptoms than other 3-OH fatty acids. Half of the surveyed 77 workers reported respiratory symptoms, 27% eye symptoms, and 10% fever or shivering. The proportion of workers with respiratory symptoms was greater when the concentration of endotoxins was over 25 ng/m3. These endotoxin levels were occasionally found in the air of most studied occupational environments. The muramic acid concentrations of peptidoglycans were highest (medians over 100 ng/m3) in the garbage-handling plant and in the grain/vegetable storage houses. The LAL assay for endotoxins, as well as the GC-MS assay analysing muramic acid for peptidoglycans or specific 3-OH fatty acids for endotoxins, seem to be suitable methods for evaluating workers' exposure to airborne bacteria.

Comparison of tanker drivers' occupational exposures before and after the installation of a vapour recovery system

The purpose of this study was to compare tanker drivers' occupational exposure level before and after the installation of vapour recovery facilities at 14 service stations. Road tanker drivers are exposed when handling volatile petrol liquid in bulk in the distribution chain. The drivers' exposure was studied during the unloading operation as the bulk petrol flowed into underground storage tanks, displacing vapours in the tank space and causing emission to the environment and the drivers' work area. The exposures were measured again when the dual point Stage I vapour recovery systems were installed for recycling vapours. Short-term measurements were carried out in the drivers' breathing zones by drawing polluted air through a charcoal tube during unloading. The samples were analysed in the laboratory by gas chromatography for C3-C11 aliphatic hydrocarbons, tert-butyl methyl ether (MTBE), tert-amyl methyl ether (MTAE), benzene, toluene and xylene. The road tanker loads delivered consisted of oxygenated and reformulated petrol (E95 and E98 brands), which contained on average 13% oxygenates. Before the installation of the vapour recovery system, the geometric mean (GM) concentration of aliphatic hydrocarbons was 65 mg m-3 (range 6-645 mg m-3) in the drivers' breathing zones. After the installation at the same service stations, the corresponding exposure level was 8.3 mg m-3 (range < 1-79 mg m-3). The GM of the MTBE concentrations was 8.6 mg m-3 (range 1-67 mg m-3) without vapour recovery and 1.5 mg m-3 (range < 0.1-10 mg m-3) with vapour recovery. The differences between the aliphatic hydrocarbons and the MTBE exposure levels during the unloading of the road tankers without and with vapour recovery were statistically significant (p < 0.05).

Applicability of homogeneous exposure groups for exposure assessment in the chemical industry

The purpose of the study was to assess occupational exposure to chemicals, by taking the aspects presented in European standard EN 689 into account, especially with respect to homogeneous exposure groups and their suitability as the basis for exposure assessment. In addition, dermal exposure to chemicals was assessed when appropriate. The industries studied included a plywood factory, a paint factory and a sewage treatment plant of an oil refinery. The workers were classified into homogeneous exposure groups by the persons in charge of occupational health issues in the respective workplaces. The concentrations of the contaminants were measured in workplace air by breathing-zone and stationary sampling, and these approaches were compared. Dermal exposure was measured when applicable. The homogeneity of the grouping was tested with analysis of variance whenever possible. The tasks studied in plywood manufacturing fulfilled the criteria of homogeneous exposure groups for both respiratory and dermal exposure. The group of operators in the sewage treatment plant was highly homogeneous. The complicated organization of the tasks made the use of homogeneous exposure groups (HEG) unsuitable at the paint factory. These findings show that reliable exposure assessment cannot be achieved with a formal standard; instead, comprehensive occupational hygiene evaluation is needed. It should also have a great importance when exposure models are developed.

Analysis of oak tannins by liquid chromatography-electrospray ionisation mass spectrometry

Extractable tannins were analysed by liquid chromatography-electrospray ionisation mass spectrometry in two oak species, North American white oak (Quercus alba) and European red oak (Quercus robur). They mainly included various glucose gallic and ellagic acid esters. The structures were partially determined, and they included grandinin/roburin E, castalagin/vescalagin, gallic acid, valoneic acid bilactone, monogalloyl glucose, digalloyl glucose, trigalloyl glucose, ellagic acid rhamnose, quercitrin and ellagic acid.

Relationship between calf muscle size and strength after achilles rupture repair

The object was to study the relationships between calf muscle size and strength in 85 patients an average of 3.1 years after repair of achilles tendon rupture. The isokinetic calf muscle strength results were excellent or good for 73% of the patients, whereas calf muscle size was normal in only 30%. The average plantar flexion peak torque per unit muscle cross-sectional area was higher on the injured side than on the uninjured side. The average calf muscle cross-sectional area deficit was 15+/-9% (p<0.001) of that on the unaffected side, while the average plantar flexion peak torque deficit was speed-dependent, being 9+/-18%, 10+/-18 and 2+/-13% of that on the unaffected side at 30, 90, and 240 degrees/sec (p<0.001). The correlation between cross-sectional area and peak torque varied in the range 0.52-0.61 at 30, 90 and 240 degrees/sec (p<0.001).

Assessment of total exposure to phenol-formaldehyde resin glue in plywood manufacturing

OBJECTIVE

Respiratory and dermal exposure to phenol-formaldehyde resin-glue components used in plywood manufacturing were assessed.

METHODS

Formaldehyde and phenol were monitored in the workplace air. Formaldehyde was measured both in the breathing zones of the workers and at stationary sampling sites. Phenol was used as a marker agent for dermal exposure due to its near-nonvolatility at the temperatures occurring during the present study and to its ready absorption through the skin, causing systemic exposure in addition to local skin rashes. Sampling and analytical methods were developed to measure the dermal exposure to phenol. Sampling was accomplished with whole-body dosimetry using Tyvek coveralls and cotton gloves. In addition, a liquid chromatography method was developed for the analysis of phenol from dermal exposure samples.

RESULTS

As expected, formaldehyde was noted to be the major compound causing respiratory exposure. When exposure assessment was done on the basis of air samples collected both at stationary sampling sites and in the breathing zones of the workers the agreement between the results obtained was good. The dermal sampling revealed that the workers were exposed to phenol, but the risk for toxic effects was slight due to the low concentrations of urinary phenol.

CONCLUSIONS

We conclude that it is possible to use the stationary sampling method for the assessment of respiratory exposure in a plywood factory instead of the usually more complicated breathing-zone sampling. This study also demonstrates the importance of taking dermal exposure into account, at least due to the ability of the resins to cause skin rashes, in assessment of the exposure to chemicals in plywood manufacturing.

Dissolution of short and long rockwool and glasswool fibers by macrophages in flowthrough cell culture

Dissolution of MMVF (man-made vitreous fibers) by macrophages has previously been studied utilizing cell cultures in wells. A new, more dynamic method has been developed to explore the effects of macrophages on MMVF dissolution. In this method, the culture medium flows through a membrane on which the macrophages and fibers are placed. The dissolution of short and long rockwool and glasswool fibers was investigated in the present study by macrophages by assessing the dissolution of Si (silicon), Fe (iron), and Al (aluminium) from the fibers. Dissolution of these elements usually increased as a function of time. Generally, the dissolution of elements from the fibers in the flowthrough culture exceeded that observed with the culture in wells system. The dissolution of glasswool fibers was greater in medium than in cell culture, whereas the opposite was true for rockwool fibers. Dissolution of Si was greater from glasswool than from rockwool fibers, while the opposite was true for Fe and Al. Macrophages that had phagocytized fibers in flowthrough culture contained Si, and there were also precipitations with Si in the samples. The fibers in the flowthrough culture also exhibited surface changes such as breakings, pittings, etching, and peeling. The short rockwool fibers tended to fracture more than short glasswool fibers, while long glasswool fibers were more extensively broken than short glasswool fibers. The results with this new, dynamic, flowthrough culture method with macrophages demonstrate that this method provides valuable information on the abilities of macrophages to dissolve MMVF leading to subsequent morphological changes of fibers.

Validation of computer-mediated open-ended standardized patient assessments

Quantitative information regarding the development of students' clinical reasoning skills is valuable in assessing third- and fourth-year medical students' clinical knowledge. Standardized patient cases are often used to obtain this quantified information. These cases typically involve a post-patient examination consisting of a series of closed-ended multiple-choice questions. Many medical educators question whether the results from the closed-ended multiple-choice questions truly reflect students' clinical knowledge and reasoning proficiency. Since 1995, the Kirksville College of Osteopathic Medicine (KCOM) has used a computer program, SOAP Note Plus, for standardized patient assessment of students to automate the post-encounter documentation and evaluation. This paper describes the development of the SOAP Note Plus program and a validation study which was conducted to determine the empirical association between the computer-mediated closed-ended and open-ended post-encounter standardized patient assessments. Correlation and GENOVA statistics were used in the analysis of the performance of third-year medical students on the closed-ended and the open-ended assessments following standardized patient encounters and the relationship to their undergraduate GPA, first 2-year medical school GPA and the actual clinical rotation evaluations. The initial results show the positive relationship between the open-ended assessment and the actual clinical rotation evaluations. undergraduate GPA and the first two-years of medical school GPA.

Exposure to airborne metals in the manufacture and maintenance of hard metal and stellite blades

This study evaluated the exposure of Finnish workers to airborne metals. It was conducted in 16 workplaces; 8 tool manufacturing companies (3 of which specialize in the maintenance of hard metal blades) and 8 blade repair shops in the mechanical wood-processing industry. The main emphasis of the study was on exposure in servicing (resharpening), especially involving wet-tip grinding processes. The results show that workers grinding hard metal blades may be exposed to high levels of airborne cobalt even when airborne total dust concentrations are low. The respirable proportion of the total dust was found to be high, and the total dust concentrations correlated well with the cobalt concentrations. Most of the airborne cobalt was water soluble (ionized), but there was also solid particles containing cobalt and other materials in the air of the workplaces. The mean concentration of cobalt in the grinding coolants was high, though it varied considerably. Concentrations of all the other metals measured in the air (tungsten, chromium, cadmium, silver, and nickel) and in the coolants (tungsten and chromium) were low. To reduce workers' exposure to cobalt, it is recommended that grinding machines should be enclosed and equipped with local exhausts. Use of coolants that dissolve less cobalt is also recommended, and the coolants should be changed more often. Brazing should be done in a well-ventilated place, and only cadmium-free materials should be used.

Biological monitoring of deltamethrin exposure in greenhouses

This study examined the possibility of using biological monitoring to assess deltamethrin exposure among greenhouse workers. The synthetic pyrethroid deltamethrin was sprayed in five greenhouses by cold for generators, and the exposure was biologically monitored by analysing the concentration of its metabolite, 3-phenoxybenzoic acid, by a gas chromato-graphic method after derivatization with pentafluorobenzyl bromide. 3-Phenoxybenzoic acid was found in the urine of two of the ten workers studied. The urine concentration of the metabolite varied from 2.4 to 51.7 micrograms/l. These results show that 3-phenoxybenzoic acid is suitable for biological monitoring for the assessment of exposure to deltamethrin.

The effect of fiber length on the dissolution by macrophages of rockwool and glasswool fibers

The effect of fiber length on the dissolution of experimental rockwool and commercial glasswood fibers in rat alveolar macrophage (AM) culture and in mere culture medium was studied. The ultrastructure of macrophages after their exposure to fibers and the suitability of macrophage-type cell line P388D1 culture in dissolution studies were also explored. The fiber samples included short (ground) and long (untreated) rockwool and glasswool fibers. The fibers were incubated in rat AM cultures, in P388D1 culture, or in mere culture medium for 4 or 8 days. The dissolution of the fibers was determined by measuring the amounts of silicon (Si), iron (Fe), and aluminum (Al) in the medium. There were no differences in the diameter of the fibers, but a clear difference existed in the length of the short and long fibers. The dissolution of Si, Fe, and Al was more pronounced from experimental rockwool than from commercial glasswool fibers. The dissolution of Si was always greater in mere culture medium than in rat AM culture. Moreover, the dissolution of Si was greater from the long fibers than from the short ones. On the contrary, the dissolution of Fe and Al in AM culture exceeded that in mere culture medium. The dissolution of Si, Fe, and Al from both fibers in P388D1 culture was similar to their dissolution in rat AM culture. The fibers were also effectively phagocytized by the macrophages. The present results together suggest that the intracellular and the extracellular dissolutions of man-made vitreous fibers differ from each other.

Spectral pattern recognition of improved voice quality

The self-organizing map (a neural network) was applied to the spectral pattern recognition of voice quality in 34 subjects: 15 patients operated on because of insufficient glottal closure and 19 subjects not treated for voice disorders. The voice samples, segments of sustained /a/, were perceptually rated by six experts. A self-organized acoustic feature map was first computed from tokens of /a/ and then used for the analysis of the samples. The locations of the samples on the map were determined and the distances from a normal reference were compared with the perceptual ratings. The map locations corresponded to the degree of audible disorder: the samples judged as normal were overlapping or close to the normal reference, whereas the samples judged as dysphonic were located further away from it. The comparison of pre- and postoperative samples of the patients showed that the perceived improvement of voice quality was also detected by the map.

Workers' exposure to airborne bacteria and endotoxins at industrial wastewater treatment plants

A study of sewage workers' exposure to airborne culturable bacteria and inhaled endotoxins was performed at nine waste-water treatment plants that treat mainly industrial effluents. Airborne endotoxins were collected on glass fiber filters and analyzed using a chromogenic limulus assay. Endotoxin concentrations measured in the immediate vicinity of the waste-water treatment process varied from 0.1 to 350 ng/m3. The eight-hour time weighted average concentrations of endotoxin to which workers were exposed exceeded the suggested exposure limit (30 ng/m3 endotoxin) at four of the plants. Air samples of culturable bacteria concentrations varied between 10 and 10(5) colony-forming units/m3. Of the particles carrying culturable bacteria, 88% had an aerodynamic diameter of less than 4.7 microns. The most common genera of airborne gram-negative bacteria were acinetobacter, citrobacter, enterobacter, klebsiella, and pseudomonas. High levels of exposure to bacteria and bacterial endotoxin usually were related to certain phases of the treatment process. The microbiological contamination of air was highest near the inlets where incoming wastewater entered the basins, in the sludge treatment area, and inside the biofilter tower. In these spaces it is necessary to control and reduce exposure to airborne bacteria and endotoxin at wastewater plants.

Self-organized acoustic feature map in detection of fricative-vowel coarticulation

The self-organizing map, a neural network algorithm of Kohonen, was used for the detection of coarticulatory variation of fricative [s] preceding vowels [a:], [i:], and [u:]. The results were compared with the psychoacoustic classification of the same samples to find out whether the map had extracted perceptually meaningful features of [s]. The map distinguished samples of [s] in front of [u:] from those in front of [a:] or [i:] throughout the fricative duration. Samples of [s] preceding [a:] and [i:] were distinguished from each other only just before (about 40 ms) the vowel onset. The results agreed with the perceptual classifications. Most judgments (82%) of [s] in front of [u:] were correct, and this variant of [s] was recognized from the first and second halves of segmented fricatives equally well. Samples of [s] in front of [a:] and [i:] were distinguished from each other less accurately. When halves of segmented [s] were perceptually judged, the differentiation between the following [a] and [i] was possible only on the basis of the second half of the fricative. The results demonstrate that the self-organizing map is a useful tool for the extraction of intersubject regularities in speech spectra. The map also provides an easily understandable, on-line, visualization of speech that can be used as feedback in therapy and education.

Exposure of sprayers and plant handlers to mevinphos in Finnish greenhouses

The exposure of sprayers and plant handlers to mevinphos, a toxic organophosphate insecticide, was evaluated in eight flower-growing greenhouses. The purpose was to assess an appropriate re-entry interval for mevinphos after its application in greenhouses. Inhalational and dermal exposure was measured during two days after application by measuring mevinphos in the greenhouse air and on the foliage. Workers' dermal exposure was measured with patch and handwash samples. The method of application considerably affected the levels of mevinphos in greenhouse air and on the foliage. The occupational exposure was measured with patch and handwash samples. The method of application considerably affected the levels of mevinphos in greenhouse air and on the foliage. The occupational exposure limit for mevinphos in Finland (100 micrograms/m3) was exceeded during the use of nonthermal foggers. Usually, however, the concentration of mevinphos in the breathing zone of the workers was below 10 micrograms/m3 9-12 hr after application. Mevinphos disappeared rapidly from greenhouse air and from the foliage after application, with a half-life of 9.2 hr. These data provide evidence that the main route of exposure to mevinphos is dermal, a conclusion supported by the excellent correlation between dermal exposure and the amount of mevinphos on the foliage. The calculated re-entry interval for mevinphos was approximately 4.5 hr. However, that interval is likely to be too short in practice because the risk of dermal exposure is considerable for more than 10 hr after the application of mevinphos.

Volatile metabolites in occupational exposure to organic sulfur compounds

Dimethyl sulfide in breath was determined by the gas chromatographic method in 14 persons exposed to organic reduced sulfur compounds in sulfate pulp mills. Dimethyl sulfide concentrations in breath (range 0.04-0.69 cm3/m3 were compared to the combined workplace concentrations of methyl mercaptan, dimethyl sulfide and dimethyl disulfide. This method of analysis proved to be a practical noninvasive way to assess recent exposure, and therefore it should be applicable to workplaces contaminated with organic sulfur compounds in the pulp industry.

Acoustic pattern recognition of fricative-vowel coarticulation by the self-organizing map

Word-initial samples of fricative [s] preceding vowels [a:], [ae:], [e:], [i:], [u:], [o:], and [y:] in Finnish words were studied with the self-organizing map. An acoustic map was first calculated from speech samples of women without speech disorders, and then the [s] samples were measured on this map. In all 10 subjects the [s] samples preceding the rounded vowels [u:] and [o:] clearly differed from the samples in front of unrounded [a:], [ae:], [e:], and [i:]. The coarticulatory phenomena observed on the map were due to changes in the composition and stability of the fricative spectrum.

Occupational exposure of forest workers to glyphosate during brush saw spraying work

The purpose of this study was to measure forest workers' exposure to the herbicide glyphosate during silvicultural clearing work done with brush saws equipped with pressurized herbicide sprayers. Both the exposed (study) group and the nonexposed (control) group contained five persons who were medically examined before and after their 1-week working period (including laboratory tests) for possible health effects. In addition, exposure to glyphosate was measured in the study group from samples taken from the workers' breathing zone and from urine samples collected during the afternoons of the workweek. The laboratory tests and urinary glyphosate analyses were repeated for the exposed group 3 weeks later, when the men had entirely stopped their work with the herbicide. Exposure to glyphosate through the workers' breathing zone was low. The highest value found was 15.7 micrograms/m3. In this study, a biological monitoring method was also developed to monitor the workers' exposure to glyphosate. Urine concentrations were under the gas chromatographic detection level of less than 0.1 ng/microL (less than 1.0 mumol/L). No major differences were noted, either in medical examinations or in the laboratory tests performed, between the exposed and control groups before and after the work period.