Incorporating species-specific morphology improves model predictions of thermal and hydric stress in the sand fiddler crab, Leptuca pugilator.

Understanding where and why organisms are experiencing thermal and hydric stress is critical for predicting species' responses to climate change. Biophysical models that explicitly link organismal functional traits like morphology, physiology, and behavior to environmental conditions can provide valuable insight into determinants of thermal and hydric stress. Here we use a combination of direct measurements, 3D modeling, and computational fluid dynamics to develop a detailed biophysical model of the sand fiddler crab, Leptuca pugilator. We compare the detailed model's performance to a model using a simpler ellipsoidal approximation of a crab. The detailed model predicted crab body temperatures within 1 °C of observed in both laboratory and field settings; the ellipsoidal approximation model predicted body temperatures within 2 °C of observed body temperatures. Model predictions are meaningfully improved through efforts to incorporate species-specific morphological properties rather than relying on simple geometric approximations. Experimental evaporative water loss (EWL) measurements indicate that L. pugilator can modify its permeability to EWL as a function of vapor density gradients, providing novel insight into physiological thermoregulation in the species. Body temperature and EWL predictions made over the course of a year at a single site demonstrate how such biophysical models can be used to explore mechanistic drivers and spatiotemporal patterns of thermal and hydric stress, providing insight into current and future distributions in the face of climate change.

Drift macroalgal distribution in northern Gulf of Mexico seagrass meadows.

Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase the value of seagrass beds as habitat for nekton via added food resources and structural complexity. But, as algal biomass increases, it can also decrease light availability, inhibit faunal movements, smother benthic communities, and contribute to hypoxia, all of which can reduce nekton abundance. We quantified the abundance and distribution of drift macroalgae within seagrass meadows dominated by turtle grass Thalassia testudinum across the northern Gulf of Mexico and compared seagrass characteristics to macroalgal biomass and distribution. Drift macroalgae were most abundant in areas with higher seagrass shoot densities and intermediate canopy heights. We did not find significant relationships between algal biomass and point measures of salinity, temperature, or depth. The macroalgal genera Laurencia and Gracilaria were present across the study region, Agardhiella and Digenia were collected in the western Gulf of Mexico, and Acanthophora was collected in the eastern Gulf of Mexico. Our survey revealed drift algae to be abundant and widespread throughout seagrass meadows in the northern Gulf of Mexico, which likely influences the habitat value of seagrass ecosystems.

Thermal ecology of the fiddler crab Uca panacea: Thermal constraints and organismal responses.

Temperature is one of the primary environmental variables limiting organismal performance, fitness, and species distributions. Yet, understanding temperature effects requires thorough exploration of thermal constraints and organismal responses that can translate to fitness and non-lethal long-term consequences under both constant and changing thermal regimes. We examined the thermal ecology of the fiddler crab Uca panacea, including critical thermal limits, thermal sensitivity of locomotion, operative environmental temperatures, preferred body temperatures, and acclimation ability. Operative environmental temperatures frequently reached the critical thermal maximum (41.8±0.8°C, mean ± s.e.m.), especially in unvegetated microhabitats, indicating the need for behavioral thermoregulation to maintain diurnal activity patterns. Preferred body temperatures (21.1-28.6°C) were substantially below the thermal optimum (30-40°C), although further research is needed to determine the driver of this mismatch. Critical thermal limits shifted 2-4°C in response to exposure to low (20°C) or high (35°C) temperatures, with full acclimation occurring in approximately 9d. This capacity for rapid acclimation, combined with the capacity for behavioral thermoregulation, is a strong candidate mechanism that explains the broad habitat use and could help explain the successful pantropical distribution of fiddler crabs.

Detecting within- and between-day manifestations of neuromuscular fatigue at work: an exploratory study.

Cumulative neuromuscular fatigue may result from exposure to physically demanding work, such as repetitive and/or sustained work with insufficient recovery. The aims of this exploratory study were to develop a battery of field usable fatigue measures and to document hand/arm fatigue in physically demanding work over multiple workdays and after a weekend break. Sixteen plumbers were observed for five days and measures of handgrip force, variability, tremor and discomfort were obtained pre-, mid- and post-shift. This exploratory study demonstrated increasing fatigue of the hand/arm over the day and persistent fatigue from Tuesday to Friday, and that a number of the measures did not return to baseline values following a weekend break. The findings provide preliminary evidence of cumulative fatigue in residential plumbing and insight into neuromuscular fatigue measurement. However, further work is needed to develop and refine a set of fatigue measures to detect neuromuscular fatigue at the workplace. PRACTITIONER SUMMARY: Cumulative fatigue has been linked to long-term health outcomes, including work-related musculoskeletal disorders. This paper presents findings from a physically demanding job (i.e. plumbing) revealing persistent fatigue over the work shift(s) and insufficient recovery after a weekend break, and provides insight into fatigue measurement at the workplace.

Microbial analysis of bite marks by sequence comparison of streptococcal DNA.

Bite mark injuries often feature in violent crimes. Conventional morphometric methods for the forensic analysis of bite marks involve elements of subjective interpretation that threaten the credibility of this field. Human DNA recovered from bite marks has the highest evidentiary value, however recovery can be compromised by salivary components. This study assessed the feasibility of matching bacterial DNA sequences amplified from experimental bite marks to those obtained from the teeth responsible, with the aim of evaluating the capability of three genomic regions of streptococcal DNA to discriminate between participant samples. Bite mark and teeth swabs were collected from 16 participants. Bacterial DNA was extracted to provide the template for PCR primers specific for streptococcal 16S ribosomal RNA (16S rRNA) gene, 16S-23S intergenic spacer (ITS) and RNA polymerase beta subunit (rpoB). High throughput sequencing (GS FLX 454), followed by stringent quality filtering, generated reads from bite marks for comparison to those generated from teeth samples. For all three regions, the greatest overlaps of identical reads were between bite mark samples and the corresponding teeth samples. The average proportions of reads identical between bite mark and corresponding teeth samples were 0.31, 0.41 and 0.31, and for non-corresponding samples were 0.11, 0.20 and 0.016, for 16S rRNA, ITS and rpoB, respectively. The probabilities of correctly distinguishing matching and non-matching teeth samples were 0.92 for ITS, 0.99 for 16S rRNA and 1.0 for rpoB. These findings strongly support the tenet that bacterial DNA amplified from bite marks and teeth can provide corroborating information in the identification of assailants.

Thermoregulation as an alternate function of the sexually dimorphic fiddler crab claw.

Fiddler crabs are highly sexually dimorphic. Males possess one small (minor) feeding claw and one greatly enlarged (major) claw; females possess two small claws. The major claw is used to attract mates and for burrow defense, but it is costly for the male to possess. We tested the hypothesis that the major claw also functions as a thermoregulatory structure, a function that would allow males to spend a greater amount of time at the surface, foraging and attracting potential mates. Fiddler crabs Uca panacea were exposed to a source of radiant heat and body temperatures were monitored. Four groups of crabs were tested: intact males, males with the minor claw removed, males with the major claw removed, and females. The body temperatures of males without the major claw increased more rapidly and reached higher values than did those of males with the major claw intact, but the results from these animals were similar to those of females. These results support the hypothesized thermoregulatory function of the major claw. The major claw may function as a heat sink, transferring heat away from the body and dissipating it into the air. Enhanced thermoregulatory ability provided by the major claw may partially ameliorate the energetic costs of possessing such a large claw.

Evidence for paternal transmission and heteroplasmy in the mitochondrial genome of Silene vulgaris, a gynodioecious plant.

Gynodioecy refers to the co-occurrence of females and hermaphrodites in the same population. In many gynodioecious plants, sex is determined by an epistatic interaction between mitochondrial and nuclear genes, resulting in intragenomic evolutionary conflict, should the mitochondrial genome be maternally inherited. While maternal inheritance of the mitochondrial genome is common in angiosperms, few gynodioecious species have been studied. Here, the inheritance of the mitochondrial genes atpA and coxI was studied in 318 Silene vulgaris individuals distributed among 23 crosses. While maternal inheritance was indicated in 96% of the individuals studied, one or more individuals from each of four sib groups displayed a genotype that was identical to the father, or that did not match either parent. Given evidence that inheritance is not strictly maternal, it was hypothesized that some individuals could carry a mixture of maternally and paternally derived copies of the mitochondrial genome, a condition known as heteroplasmy. Since heteroplasmy might be difficult to detect should multiple versions of the mitochondrial genome co-occur in highly unequal copy number, a method was devised to amplify low-copy number forms of atpA differentially. Evidence for heteroplasmy was found in 23 of the 99 individuals studied, including cases in which the otherwise cryptic form of atpA matched the paternal genotype. The distribution of shared nucleotide sequence polymorphism among atpA haplotypes and the results of a population survey of the joint distribution of atpA and coxI haplotypes across individuals supports the hypothesis that heteroplasmy facilitates formation of novel mitochondrial genotypes by recombination.

Inactivation of respiratory syncytial virus by generic hand dishwashing detergents and antibacterial hand soaps.

In an in-vitro test, generic liquid hand dishwashing detergents were as much as 100-fold more effective than proprietary antibacterial soaps in inactivating respiratory syncytial virus (RSV). The use of such detergents for hand washing during annual RSV epidemics, or the incorporation of their antiviral components into antibacterial soaps might be considered to limit nosocomial spread.

Immunoprophylaxis of group B respiratory syncytial virus infection in cotton rats.

Two antigenic groups of respiratory syncytial virus (RSV) have been identified: A (RSV/A) and B (RSV/B). Topical administration of human IgG screened for high titers of antibody to RSV/A (RSVIg) is protective against RSV/A infection in the cotton rat model. The study attempted to determine if topical RSVIg would also be protective against RSV/B. Cotton rats were pretreated intranasally with RSVIg or with monospecific antiserum obtained from animals previously infected with RSV/A or RSV/B (day 0), challenged intranasally with RSV/A or RSV/B (day 1), and sacrificed for virus titration (day 5). Cotton rat antiserum to RSV/B protected against RSV/A and RSV/B, while antiserum to RSV/A protected only against RSV/A. RSVIg, although prepared on the basis of activity against RSV/A, was also protective against RSV/B.

Unilateral nasal infection of cotton rats with respiratory syncytial virus allows assessment of local and systemic immunity.

An in vivo model for the study of local and systemic effectors of immunity to respiratory syncytial virus (RSV) is described. Cotton rats (Sigmodon fulviventer) inoculated in one nostril with a small volume (2 microliters) of virus suspension contracted a unilateral nasal infection which did not extend to the contralateral nasal turbinates, nor to the lungs. Immunity to subsequent RSV challenge could be induced by small priming doses ( < 10 p.f.u. per animal), but was dependent upon viral replication, as virus inactivated by UV light was not immunogenic. Immunity occurred in the absence of detectable neutralizing serum antibody. The onset of resistance to viral challenge occurred simultaneously in ipsilateral nasal, contralateral nasal and pulmonary tissues. However, low levels of transient viral replication occurred in contralateral nasal turbinates and in lungs following virus challenge, thus indicating that local components of immunity acting at the ipsilateral site of infection were more effective than systemic components acting at the other sites. Further evidence is provided to suggest that three types of immunological effectors - local, persistent, systemic and transient systemic - participate in the immune response to RSV infection.

Topical immunoglobulin is an effective therapy for parainfluenza type 3 in a cotton rat model.

A cotton rat model was used to test the efficacy of topical immunotherapy against parainfluenza type 3 (PIV3) infection. On day 3 after experimental infection with 10(5.5) pfu of PIV3, animals were treated with 2-fold dilutions of convalescent cotton rat serum or with one of two purified human immunoglobulin preparations; all three had moderate titers of anti-PIV3 neutralizing antibody (range, 1:200-1:1000). Therapy with high concentrations of all three preparations resulted in significant reductions of > or = 2 logs (> or = 100-fold) of pulmonary virus titers compared with titers for control animals. Little or no reduction in virus titers were seen in nasal tissues.

A cotton rat model of effectors of immunity to respiratory syncytial virus other than serum antibody.

A model for studying effectors of immunity to respiratory syncytial virus (RSV) was developed. Paris of inbred cotton rats (Sigmodon hispidus) were joined surgically using the technique of parabiosis. One week later, one animal of each pair was primed intranasally with a small volume of RSV suspension. Fourteen days after priming, both animals of each pair were bled for determination of serum neutralizing antibody titers, and challenged intranasally with a standard dose of RSV suspension. Single, unprimed cotton rats were challenged concomitantly and served as controls. Four days after challenge, all animals were sacrificed for virus titration of nasal tissues and lungs. Parabiosed cotton rats were surgically separated at varying intervals between priming and challenge (days 7, 9, 12, or 14 after priming) or were kept joined until sacrificed (day 18). Significant transfer of nasal and pulmonary immunity from primed to unprimed parabionts began 9 days after priming, gradually increasing through 18 days. Resistance to RSV challenge in spite of low levels of serum neutralizing antibody suggests that non-antibody immunologic mediators were responsible for the transferred immunity. Evidence is presented for three broad categories of RSV immunologic effectors: systemic, local with a transient systemic phase, and local without a systemic phase. These categories are now amenable to further study using the described model.

Systemic immunoprophylaxis of nasal respiratory syncytial virus infection in cotton rats.

The cotton rat model was used to test whether systemically administered immunoglobulin could protect nasal tissues against low challenge doses of respiratory syncytial virus (RSV). Animals were pretreated by intraperitoneal injection of human immunoglobulin with moderate (1:2226) or high (1:15,000) neutralizing antibody titers to RSV (day 0), challenged intranasally with RSV Long at doses ranging from 10(1) to 10(5) pfu (day 1), and sacrificed for virus titration (day 5). Pretreatment with moderate-titer immunoglobulin effected complete or near complete nasal protection against low to moderate (10(1)-10(3) pfu) RSV challenge doses and a significant reduction in nasal RSV titers at high (10(4)-10(5) pfu) challenge doses. Pretreatment with high-titer immunoglobulin effected near complete nasal protection at an RSV challenge dose of 10(3) pfu and highly significant and significant reductions in nasal RSV titers at challenge doses of 10(4) and 10(5) pfu, respectively. Immunoprophylaxis effected complete or near complete pulmonary protection at all RSV challenge doses.

Rehabilitation of the temporomandibular joint through the application of motion.

This paper presents a method of joint rehabilitation utilizing the principals of active motion and CPM (continuous passive motion) and joint unloading. Most true intra-articular disorders appear to be a progression of both chemical and mechanical alterations. The physiological sound principals of joint mobilization are used both as post surgical rehabilitation and as definitive therapy. When used as nonsurgical therapy, the benefits appear to be as a result of a reversal, lessening, or a favorable adaptive response of the chemical and mechanical alterations.

Adenosine is a mediator of ethanol-induced gastric vasodilation in dogs.

The purpose of this study was to assess the role of histamine, adenosine, and prostaglandins as mediators of ethanol-induced gastric vasodilation. In an ex vivo segment of canine stomach, vasodilation occurred within the first minute of replacing luminal saline with ethanol (40% vol/vol). Ethanol caused vascular resistance to progressively decrease by approximately 53% compared with control values. In other experiments, intra-arterial infusion of histamine (300 ng/ml) or adenosine (30 micrograms/ml) to the gastric segment produced similar degrees of vasodilation as observed with ethanol. The response to these vasodilators could be markedly attenuated with specific antagonists of these substances (histamine: pyrilamine plus cimetidine; adenosine: 8-phenyltheophylline). In our final experiments, indomethacin or histamine- or adenosine-receptor antagonists were given before application of topical ethanol. Indomethacin or histamine antagonists had no significant effect on the time course or magnitude of ethanol-induced vasodilation. In contrast, pretreatment with 8-phenyltheophylline significantly reduced changes in vascular resistance during exposure to luminal ethanol. These results suggest that locally released adenosine is an important mediator of ethanol-induced vasodilation in the canine stomach under these conditions.

Bovine respiratory syncytial virus protects cotton rats against human respiratory syncytial virus infection.

Human respiratory syncytial virus (HRSV) is the most frequent cause of severe respiratory infections in infancy. No vaccine against this virus has yet been protective, and antiviral drugs have been of limited utility. Using the cotton rat model of HRSV infection, we examined bovine respiratory syncytial virus (BRSV), a cause of acute respiratory disease in young cattle, as a possible vaccine candidate to protect children against HRSV infection. Cotton rats were primed intranasally with graded doses of BRSV/375 or HRSV/Long or were left unprimed. Three weeks later, they were challenged intranasally with either BRSV/375, HRSV/Long (subgroup A), or HRSV/18537 (subgroup B). At intervals postchallenge, animals were sacrificed for virus titration and histologic evaluation. Serum neutralizing antibody titers were determined at the time of viral challenge. BRSV/375 replicated to low titers in nasal tissues and lungs. Priming with 10(5) PFU of BRSV/375 effected a 500- to 1,000-fold reduction in peak nasal HRSV titer and a greater than 1,000-fold reduction in peak pulmonary HRSV titer upon challenge with HRSV/Long or HRSV/18537. In contrast to priming with HRSV, priming with BRSV did not induce substantial levels of neutralizing antibody against HRSV and was associated with a delayed onset of clearance of HRSV upon challenge. Priming with BRSV/375 caused mild nasal and pulmonary pathology and did not cause exacerbation of disease upon challenge with HRSV/Long. Our findings suggest that BRSV may be a potential vaccine against HRSV and a useful tool for studying the mechanisms of immunity to HRSV.

Immunotherapy of respiratory syncytial virus infection in cotton rats (Sigmodon fulviventer) using IgG in a small-particle aerosol.

To determine whether aerosolized IgG can be used effectively in the treatment of respiratory syncytial virus (RSV) infections, cotton rats were infected intranasally with RSV and treated 3 days later with human IgG containing anti-RSV antibodies delivered in a small-particle aerosol. Pulmonary histology and virus titers were determined 24 h after IgG treatment. A single 15-min exposure to aerosolized IgG did not exacerbate pulmonary pathology and effected a 50-fold reduction in pulmonary virus titer (2.95 vs. 4.67 log10 geometric mean pfu/g for untreated controls, P < .001), which was comparable to that effected by intranasally instilled IgG (50 mg/kg) (3.24 vs. 4.67 log10 geometric mean pfu/g for controls, P < .001). A 15-min exposure to aerosolized ribavirin (20 mg/mL) was not effective in reducing pulmonary virus. This study suggests that aerosolized IgG could be useful in the treatment of RSV lower respiratory tract infections and that it compares favorably with ribavirin.

Creatine kinase MB in cases of skeletal muscle trauma.

Fifty-eight patients admitted through our emergency room with severe skeletal muscle injury but no obvious cardiac contusions were evaluated for creatine kinase isoenzyme MB (CK-MB). When such patients show an above-normal value for total CK, it is a question of whether or not myocardial injury has been sustained along with skeletal muscle injury when (a) there are no obvious chest contusions or (b) the patient is unconscious and unable to complain of chest pain. Whenever there is doubt concerning the cardiac status of a patient, lactate dehydrogenase (LD) isoenzymes, serial electrocardiograms, and CK isoenzymes are ordered. Our study revealed that serum of 8.6% of the trauma victims had CK-MB values exceeding 5.0 EU/L (reflecting abnormal CK-MB concentrations) as part of their increased total CK. All patients had normal electrocardiographic patterns along with negative results for LD isoenzymes; none had sustained any demonstrable myocardial injury. The CK-MB value must be interpreted together with the total CK value for appropriate diagnosis in patients with skeletal muscle trauma.