Environmental risk assessment of propofol in wastewater: a narrative review of regulatory guidelines.

Concerns relating to the negative environmental impacts of anaesthesia are increasing, and in recent years, there has been an environmentally motivated trend towards greater use of propofol-based total intravenous anaesthesia. Consequently, the environmental burden of propofol waste and disposal, particularly into wastewater, has gained attention. Current literature reporting levels of propofol in wastewater are scarce and the threat this presents to the environment is unclear. We review the regulatory requirements for conducting an environmental risk assessment, with a focus on the process for analysing whether drugs or drug metabolites cause harm to aquatic species. Furthermore, we present a profile for the aquatic toxicity of propofol based on available data and discuss the implications of this for future practice.

The 2018 rift eruption and summit collapse of Kilauea Volcano.

In 2018, Kilauea Volcano experienced its largest lower East Rift Zone (LERZ) eruption and caldera collapse in at least 200 years. After collapse of the Pu'u 'O'o vent on 30 April, magma propagated downrift. Eruptive fissures opened in the LERZ on 3 May, eventually extending ~6.8 kilometers. A 4 May earthquake [moment magnitude (M w) 6.9] produced ~5 meters of fault slip. Lava erupted at rates exceeding 100 cubic meters per second, eventually covering 35.5 square kilometers. The summit magma system partially drained, producing minor explosions and near-daily collapses releasing energy equivalent to M w 4.7 to 5.4 earthquakes. Activity declined rapidly on 4 August. Summit collapse and lava flow volume estimates are roughly equivalent-about 0.8 cubic kilometers. Careful historical observation and monitoring of Kilauea enabled successful forecasting of hazardous events.

Learning and CRF-Induced Indecision during Escape and Submission in Rainbow Trout during Socially Aggressive Interactions in the Stress-Alternatives Model.

Socially stressful environments induce a phenotypic dichotomy of coping measures for populations in response to a dominant aggressor and given a route of egress. This submission- (Stay) or escape-oriented (Escape) dichotomy represents individual decision-making under the stressful influence of hostile social environments. We utilized the Stress-Alternatives Model (SAM) to explore behavioral factors which might predict behavioral phenotype in rainbow trout. The SAM is a compartmentalized tank, with smaller and larger trout separated by an opaque divider until social interaction, and another divider occluding a safety zone, accessible by way of an escape route only large enough for the smaller fish. We hypothesized that distinctive behavioral responses during the first social interaction would indicate a predisposition for one of the behavioral phenotypes in the subsequent interactions. Surprisingly, increased amount or intensity of aggression received had no significant effect on promoting escape in test fish. In fact, during the first day of interaction, fish that turned toward their larger opponent during attack eventually learned to escape. Escaping fish also learn to monitor the patrolling behavior of aggressors, and eventually escape primarily when they are not being observed. Escape per se, was also predicted in trout exhibiting increased movements directed toward the escape route. By contrast, fish that consistently remained in the tank with the aggressor (Stay) showed significantly higher frequency of swimming in subordinate positions, at the top or the bottom of the water column, as well as sitting at the bottom. In addition, a corticotropin-releasing factor (CRF)-induced behavior, snap-shake, was also displayed in untreated fish during aggressive social interaction, and blocked by a CRF1 receptor antagonist. Especially prevalent among the Stay phenotype, snap-shake indicates indecision regarding escape-related behaviors. Snap-shake was also exhibited by fish of the Escape phenotype, showing a positive correlation with latency to escape. These results demonstrate adaptive responses to stress that reflect evolutionarily conserved stress neurocircuitry which may translate to psychological disorders and decision-making across vertebrate taxa.

Complex Reproductive Traits and Whole-Organism Performance.

SYNOPSIS: Arnold's 1983 path-analytic paradigm, considering "morphology, performance, and fitness," has been elaborated in several ways. For example, current versions recognize the level of "behavior" (including aspects of motivation) as a filter between performance abilities (only measurable if motivation is maximal) and fitness components. Performance abilities constrain behavior, but behavioral choices may shield performance from selection. Conceptual and empirical issues remain, such as the extent to which individual variation in lower-level subordinate traits (e.g., circulating hormone concentrations) might directly affect behavior, growth rates, sexual maturation, etc., rather than having effects only through paths involving some aspect of performance. Moreover, empirical studies have yet to encompass more than a few possible paths in a given system, in part because life-history researchers rarely communicate with those focused on performance. Most life-history studies ponder trade-offs associated with reproductive effort, but studies of locomotor performance (e.g., maximal sprint speed) have rarely considered trade-offs with reproduction. This lack of connection is surprising because both life history (e.g., clutch size) and locomotor performance (e.g., locomotor stamina) traits require allocation of energy and other resources, so trade-offs between these trait types may be expected. These perspectives and cultures could be bridged by a focus on the ability of organisms to perform components of reproductive biology (e.g., lactation performance could be studied in animals maximally "motivated" by manipulation of litter size or endocrine function). Alternatively, one could study impacts of reproduction on performance, as when bats and live-bearing fishes lose maneuverability during gestation. We also consider sperm performance in the context of the paradigm and illustrate that the paradigm can easily be utilized as a frame-work within which to consider key aspects of sperm biology.

Compliance of the L5-S1 spinal unit: a comparative study between an unconstrained and a partially constrained system.

A comparison between an unconstrained and a partially constrained system for in vitro biomechanical testing of the L5-S1 spinal unit was conducted. The objective was to compare the compliance and the coupling of the L5-S1 unit measured with an unconstrained and a partially constrained test for the three major physiological motions of the human spine. Very few studies have compared unconstrained and partially constrained testing systems using the same cadaveric functional spinal units (FSUs). Seven human L5-S1 units were therefore tested on both a pneumatic, unconstrained, and a servohydraulic, partially constrained system. Each FSU was tested along three motions: flexion-extension (FE), lateral bending (LB) and axial rotation (AR). The obtained kinematics on both systems is not equivalent, except for the FE case, where both motions are similar. The directions of coupled motions were similar for both tests, but their magnitudes were smaller in the partially constrained configuration. The use of a partially constrained system to characterize LB and AR of the lumbosacral FSU decreased significantly the measured stiffness of the segment. The unconstrained system is today's "gold standard" for the characterization of FSUs. The selected partially constrained method seems also to be an appropriate way to characterize FSUs for specific applications. Care should be taken using the latter method when the coupled motions are important.

Taste-aversion-prone (TAP) rats and taste-aversion-resistant (TAR) rats differ in ethanol self-administration, but not in ethanol clearance or general consumption.

Taste-aversion (TA)-prone (TAP) rats and TA-resistant (TAR) rats have been developed by means of bidirectional selective breeding on the basis of their behavioral responses to a TA conditioning paradigm. The TA conditioning involved the pairing of an emetic-class agent (cyclophosphamide) with a novel saccharin solution as the conditioned stimulus. Despite the absence of ethanol in the selective breeding process, these rat lines differ widely in ethanol self-administration. In the current study, blood alcohol concentrations (BACs) were determined after 9 days of limited (2 h per day) access to a simultaneous, two-bottle choice of a 10% ethanol in water solution [volume/volume (vol./vol.)] or plain water. The BACs correlated highly with ethanol intake among TAR rats, but an insufficient number of TAP rats yielded measurable BACs to make the same comparison within this rat line. The same rats were subsequently exposed to 24-h access of a two-bottle choice (10% ethanol or plain water) for 8 days. Ethanol consumption during the 24-h access period correlated highly with that seen during limited access. Subsequent TA conditioning with these rats yielded line-typical differences in saccharin preferences. In a separate group of rats, ethanol clearance was determined by measuring BACs at 1, 4, and 7 h after injection of a 2.5-g/kg dose of ethanol. Ethanol clearance was not different between the two lines. Furthermore, the lines did not differ with respect to food and water consumption. Therefore, the TAP rat-TAR rat differences in ethanol consumption cannot be attributed to line differences in ethanol metabolism or in general consummatory behavior. The findings support our contention that the line differences in ethanol consumption are mediated by differences in TA-related mechanisms. The findings are discussed with respect to genetically based differences in the subjective experience of ethanol.

Animation of in vitro biomechanical tests.

Interdisciplinary communication of three-dimensional kinematic data arising from in vitro biomechanical tests is challenging. Complex kinematic representations such as the helical axes of motion (HAM) add to the challenge. The difficulty increases further when other quantities (i.e. load or tissue strain data) are combined with the kinematic data. The objectives of this study were to develop a method to graphically replay and animate in vitro biomechanical tests including HAM data. This will allow intuitive interpretation of kinematic and other data independent of the viewer's area of expertise. The value of this method was verified with a biomechanical test investigating load-sharing of the cervical spine. Three 3.0 mm aluminium spheres were glued to each of the two vertebrae from a C2-3 segment of a human cervical spine. Before the biomechanical tests, CT scans were made of the specimen (slice thickness=1.0 mm and slice spacing=1.5 mm). The specimens were subjected to right axial torsion moments (2.0 Nm). Strain rosettes mounted to the anterior surface of the C3 vertebral body and bilaterally beneath the facet joints on C3 were used to estimate the force flow through the specimen. The locations of the aluminium spheres were digitised using a space pointer and the motion analysis system. Kinematics were measured using an optoelectronic motion analysis system. HAMs were calculated to describe the specimen kinematics. The digitised aluminium sphere locations were used to match the CT and biomechanical test data (RMS errors between the CT and experimental points were less than 1.0 mm). The biomechanical tests were "replayed" by animating reconstructed CT models in accordance with the recorded experimental kinematics, using custom software. The animated test replays allowed intuitive analysis of the kinematic data in relation to the strain data. This technique improves the ability of experts from disparate backgrounds to interpret and discuss this type of biomechanical data.

Compressive properties of cancellous bone defects in a rabbit model treated with particles of natural bone mineral and synthetic hydroxyapatite.

A rabbit model was developed to evaluate the compressive mechanical properties of cancellous bone defects treated with particles of selected bone graft substitute materials. A novel feature of the model was the precise retrieval of the site of implantation. A notable finding was a 9-fold increase in the modulus of elasticity of the defect implanted with a synthetic hydroxyapatite material after 26 weeks when compared to the modulus of the trabecular bone normally at the site. The compressive modulus of lesions treated with particles of a natural bovine bone mineral (anorganic bovine bone) was closer to the normal modulus of the cancellous bone at the site. While the compressive strength of the anorganic bone particles was less than that of normal bone, the site implanted with the bone mineral particles achieved compressive strength greater than normal after 6 weeks. Moreover, the anorganic bone particles accelerated the increase in strength of the lesion, at 6 weeks exceeding the strength achieved by the untreated defect after 26 weeks. The potential problem associated with the disparity in the compressive modulus between sites implanted with the synthetic HA particles and surrounding bone is discussed.

Depression, pain, exposure to stressful life events, and long-term outcomes in temporomandibular disorder patients.

PURPOSE: This study investigated the role of psychological factors in temporomandibular disorders (TMD). Orofacial pain patients' pretreatment levels of depression, disability caused by pain, and exposure to stressful life events were measured, and differences on these variables between temporomandibular joint (TMJ) disease patients and patients whose pain was of muscular origin (MPD) were evaluated. The use of these variables and patient diagnostic status in predicting response to treatment in a subsample of these patients was also evaluated. PATIENTS AND METHODS: Before undergoing treatment, 258 patients were administered the Beck Depression Inventory (BDI), the Pain Disability Index (PDI), and the Social Readjustment Rating Scale (SRRS). Follow-up data on pain disability, current level of pain, depression, and satisfaction with treatment were obtained on 48 of these patients who were contacted at varying intervals after completing treatment. RESULTS: BDI scores obtained at the outset of treatment were significantly elevated and were positively correlated with SRRS and PDI scores. MPD patients had higher SRRS, BDI depression, and PDI pain disability scores than TMJ patients, and differences between the 2 groups in pain disability were greatest in areas that are often sources of interpersonal stress. Among follow-up patients, PDI scores declined after treatment, with MPD patients showing greater decreases than TMJ patients. Independent of patients' diagnostic status, their pretreatment PDI scores were predictive of their pain level at follow-up and were inversely related to their degree of satisfaction with treatment at follow-up; their pretreatment BDI scores were predictive of their depression level at follow-up. CONCLUSIONS: The findings are consistent with previous research indicating a link between emotional dysfunction and TMD and are largely supportive of the conclusion that psychological factors play a more pronounced role when pain is of muscular origin. Promising behavioral interventions are available for TMD patients in whom psychological factors appear to be playing a significant role.

In vitro axial preload application during spine flexibility testing: towards reduced apparatus-related artefacts.

Presently, there is little consensus about how, or even if, axial preload should be incorporated in spine flexibility tests in order to simulate the compressive loads naturally present in vivo. Some preload application methods are suspected of producing unwanted "artefact" forces as the specimen rotates and, in doing so, influencing the resulting kinematics. The objective of this study was to quantitatively compare four distinct types of preload which have roots in contemporary experimental practice. The specific quantities compared were the reaction moments and forces resulting at the intervertebral disc and specimen kinematics. The preload types incorporated increasing amounts of caudal constraint on the preload application vector ranging from an unconstrained dead-load arrangement to an apparatus that allowed the vector to follow rotations of the specimen. Six human cadaveric spine segments were tested (1-L1/L2, 3-L2/L3, 1-L3/L4 and 1-L4/L5). Pure moments were applied to the specimens with each of the four different types of compressive preload. Kinematic response was measured using an opto-electronic motion analysis system. A six-axis load cell was used to measure reaction forces and moments. Artefact reaction moments and shear forces were significantly affected by preload application method and magnitude. Unconstrained preload methods produced high artefact moments and low artefact shear forces while more constrained methods did the opposite. A mechanical trade-off is suggested by our results, whereby unwanted moment can only be prevented at the cost of shear force production. When comparing spine flexibility studies, caution should be exercised to ensure preload was applied in a similar manner for all studies. Unwanted moments or forces induced as a result of preload application method may render the comparison of two seemingly similar studies inappropriate.

Serotonin reuptake is less efficient in taste aversion resistant than in taste aversion-prone rats.

We have previously reported the development of rat lines bred selectively for differences in taste aversion conditionability. Earlier studies demonstrated that the taste aversion resistant (TAR) animals exhibited lower concentrations of brain serotonin and consumed greater amounts of ethanol than their taste aversion prone (TAP) counterparts. In the present study, TAR rats demonstrated significantly less efficient brain serotonin transport compared to TAP rats, but the rat lines demonstrated similar levels of serotonin transporter or V(max) and similar whole brain paroxetine (a specific serotonin reuptake inhibitor) binding (B(max)). These results suggest that the rat lines differ in the mechanisms that transport serotonin into nerve endings, but do not differ in the binding of serotonin to the transporter or in the number of serotonin transport sites. The data support the hypothesis that genetically determined differences in the serotonin system contribute to individual differences in taste aversion conditionability. The findings further suggest that differences in serotonin transport may influence the propensity to self-administer ethanol.

Virtual reality for mine safety training.

Mining has long remained one of America's most hazardous occupations. Researchers believe that by developing realistic, affordable VR training software, miners will be able to receive accurate training in hazard recognition and avoidance. In addition, the VR software will allow miners to follow mine evacuation routes and safe procedures without exposing themselves to danger. This VR software may ultimately be tailored to provide training in other industries, such as the construction, agricultural, and petroleum industries.

Three-dimensional measurement of cemented femoral stem stability: an in vitro cadaver study.

OBJECTIVE: To compare the in vitro stability of two cemented hip stem designs: Stem I was a collarless, double-tapered, highly polished implant; Stem II had a collar and matt finish. BACKGROUND: Stability of the femoral component of a hip implant is important for its long-term clinical success. Excessive migration or cyclic motion can increase the risk of early implant failure. METHODS: The stems were implanted in paired human cadaver femurs, and custom-designed micromotion sensors were used to measure three-dimensional motions of the stems at proximal, middle and distal locations during simulated in vivo loading cycles. RESULTS: This study found that despite 'rigid' fixation, cemented stems exhibit detectable motions under a limited number of cycles of simulated physiologic loads. At four times the donor body weight, Stem I showed a subsidence of 90 microm, compared to 25 microm of Stem II (P<0.05). In contrast, the proximal end of Stem II exhibited greater cyclic motions in the medial-lateral direction (P<0.05). CONCLUSIONS: The different motion patterns could be due to the design differences, such as surface finish and geometry. RelevanceImplant design is an important factor related to the behavior of the cement/bone interface and the overall success of the implant. This study compares in vitro micromotion of two cemented femoral prostheses with differing proximal designs.