Behavioural adjustments of predators and prey to wind speed in the boreal forest.

Wind speed can have multifaceted effects on organisms including altering thermoregulation, locomotion, and sensory reception. While forest cover can substantially reduce wind speed at ground level, it is not known if animals living in forests show any behavioural responses to changes in wind speed. Here, we explored how three boreal forest mammals, a predator and two prey, altered their behaviour in response to average daily wind speeds during winter. We collected accelerometer data to determine wind speed effects on activity patterns and kill rates of free-ranging red squirrels (n = 144), snowshoe hares (n = 101), and Canada lynx (n = 27) in Kluane, Yukon from 2015 to 2018. All 3 species responded to increasing wind speeds by changing the time they were active, but effects were strongest in hares, which reduced daily activity by 25%, and lynx, which increased daily activity by 25%. Lynx also increased the number of feeding events by 40% on windy days. These results highlight that wind speed is an important abiotic variable that can affect behaviour, even in forested environments.

Optimisation of energetic and reproductive gains explains behavioural responses to environmental variation across seasons and years.

Animals switch between inactive and active states, simultaneously impacting their energy intake, energy expenditure and predation risk, and collectively defining how they engage with environmental variation and trophic interactions. We assess daily activity responses to long-term variation in temperature, resources and mating opportunities to examine whether individuals choose to be active or inactive according to an optimisation of the relative energetic and reproductive gains each state offers. We show that this simplified behavioural decision approach predicts most activity variation (R2  = 0.83) expressed by free-ranging red squirrels over 4 years, as quantified through accelerometer recordings (489 deployments; 5066 squirrel-days). Recognising activity as a determinant of energetic status, the predictability of activity variation aggregated at a daily scale, and the clear signal that behaviour is environmentally forced through optimisation of gain, provides an integrated approach to examine behavioural variation as an intermediary between environmental variation and energetic, life-history and ecological outcomes.

Post-weaning parental care increases fitness but is not heritable in North American red squirrels.

Most empirical attempts to explain the evolution of parental care have focused on its costs and benefits (i.e. fitness consequences). In contrast, few investigations have been made of the other necessary prerequisite for evolutionary change, inheritance. Here, we examine the fitness consequences and heritability (h(2)) of a post-weaning parental care behaviour (territory bequeathal) in a wild population of North American red squirrels. Each year, a subset (average across all years = 19%) of reproductive females bequeathed their territory to a dependent offspring. Bequeathing females experienced higher annual reproductive success and did not suffer a survival cost to themselves relative to those females retaining their territory. Bequeathing females thus realized higher relative annual fitness [ω = 1.18 ± 0.03 (SE)] than nonbequeathing females [ω = 0.96 ± 0.02 (SE)]. Additive genetic influences on bequeathal behaviour, however, were not significantly different from 0 (h(2) = 1.9 × 10(-3); 95% highest posterior density interval = 3.04 × 10(-8) to 0.37) and, in fact, bequeathal behaviour was not significantly repeatable (R = 2.0 × 10(-3); 95% HPD interval = 0-0.27). In contrast, directional environmental influences were apparent. Females were more likely to bequeath in years following low food abundance and when food availability in the upcoming autumn was high. Despite an evident fitness benefit, a lack of heritable genetic variance will constrain evolution of this trait.

The failing Fontan: what's NEXT...?

The Fontan procedure represents the final stage of the transition to single ventricle physiology. Conversion of very complex congenital heart anatomy, such as hypoplastic left heart syndrome, double-outlet right ventricle or double-inlet left ventricle, to a single ventricle has grown in popularity as morbidity and mortality have improved. As these patients grow, survivors are at risk for impaired ventricular dysfunction, plastic bronchitis, protein-losing enteropathy and late failure. Late failing Fontan patients represent a particularly vexing scenario for clinicians, as the only durable treatment option is cardiac transplantation. However, in the short-term, some of these patients require support beyond medical management, with mechanical circulatory support via extracorporeal life support or a ventricular assist device. We report the successful bridge of an adolescent female post-Fontan conversion with late severe cardiac failure. The patient was initially resuscitated with extracorporeal life support, transitioned to a single Berlin Heart EXCOR® ventricular assist device and, subsequently, underwent successful cardiac transplantation.

A quantitative genetic analysis of hibernation emergence date in a wild population of Columbian ground squirrels.

The life history schedules of wild organisms have long attracted scientific interest, and, in light of ongoing climate change, an understanding of their genetic and environmental underpinnings is increasingly becoming of applied concern. We used a multi-generation pedigree and detailed phenotypic records, spanning 18 years, to estimate the quantitative genetic influences on the timing of hibernation emergence in a wild population of Columbian ground squirrels (Urocitellus columbianus). Emergence date was significantly heritable [h(2) = 0.22 ± 0.05 (in females) and 0.34 ± 0.14 (in males)], and there was a positive genetic correlation (r(G) = 0.76 ± 0.22) between male and female emergence dates. In adult females, the heritabilities of body mass at emergence and oestrous date were h(2) = 0.23 ± 0.09 and h(2) = 0.18 ± 0.12, respectively. The date of hibernation emergence has been hypothesized to have evolved so as to synchronize subsequent reproduction with upcoming peaks in vegetation abundance. In support of this hypothesis, although levels of phenotypic variance in emergence date were higher than oestrous date, there was a highly significant genetic correlation between the two (r(G) = 0.98 ± 0.01). Hibernation is a prominent feature in the annual cycle of many small mammals, but our understanding of its influences lags behind that for phenological traits in many other taxa. Our results provide the first insight into its quantitative genetic influences and thus help contribute to a more general understanding of its evolutionary significance.

Detection of Trypanosoma cruzi with the polymerase chain reaction and in situ hybridization in infected murine cardiac tissue.

Chagas' disease is caused by the hemoflagellate protozoan Trypanosoma cruzi, which is predominantly found in South and Central America and Mexico. Although the parasite is present in the United States, confirmed cases of human disease are rare. The most serious manifestation of chronic Chagas' disease is a progressive inflammatory cardiomyopathy. However, T. cruzi has not been consistently demonstrated with histologic techniques in inflammatory cardiac lesions. In this study, we used both polymerase chain reaction (PCR) amplification of extracted DNA from hematoxylin and eosin-stained tissue scrapings, and in situ hybridization to detect the presence of T. cruzi in infected murine cardiac tissue sections. Three T. cruzi-specific DNA sequences were used: a 122-basepair (bp) sequence localized within the minicircle network (MCS), a 188-bp nuclear repetitive sequence (RS), and a 177-bp sequence within the open reading frame of a gene coding for a flagellar protein (FPS). We found that all three sequences are amplifiable from scrapings of murine cardiac tissue. The MCS and RS are detected at 0.167 and 0.24 amastigote DNA equivalents, while FPS is barely detected at 0.24 amastigote DNA equivalents. On the other hand, in situ hybridization with all three sequences allowed for the detection of T. cruzi amastigotes within the tissue. The MCS and FPS, however, consistently yielded a more intense signal. These results indicate that PCR and in situ hybridization may prove useful in establishing the prevalence of T. cruzi in human chagasic cardiomyopathy.

In vitro trypanocidal activity of tetraethylthiuram disulfide and sodium diethylamine-N-carbodithioate on Trypanosoma cruzi.

Tetraethylthiuram disulfide (disulfiram) (TETD) and sodium diethylamine-N-carbodithioate (DECD) were examined for their in vitro trypanocidal activity against Trypanosoma cruzi. Benznidazole (BNZ), the drug used clinically for the chemotherapy of Chagas' disease, was used as a positive control. Inhibition assays included evaluation against the epimastigote, trypomastigote, and amastigote forms. Tetraethylthiuram disulfide and its reductive metabolite DECD inhibited 64.6% and 69.7%, respectively, of epimastigotes at a concentration of 50 micrograms/ml after 72 hr and BNZ caused 69.1% inhibition at the same concentration. Both TETD and DECD were not as effective against tissue culture trypomastigotes as BNZ (TETD = 47.7%,; DECD = 46.1%; BNZ = 88.7%) at 50 micrograms/ml after 24 hr. However, TETD and DECD treatment of amastigote-infected 3T3 fibroblasts yielded 60 and 67% inhibition, respectively, as compared to BNZ with an inhibition of 62%. A possible mechanism of action of TETD and DECD is via interference with the essential metal metabolism of T. cruci. Since toxicity data for both TETD and DECD are available and both drugs are active against the parasite, these drugs are candidates for further study to determine if they are of potential clinical interest as a prophylactic or therapeutic agent against Chagas' disease.

Chelating agent inhibition of Trypanosoma cruzi epimastigotes in vitro.

A number of chelating agents and some of their derivatives are as effective as, or superior to, benznidazole, the compound currently in clinical use, in the suppression of the reproduction of epimastigotes of Trypanosoma cruzi, the protozoa that causes Chagas' disease. All compounds were examined at a culture concentration of 5 micrograms/mL. The most effective compounds included N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine, sodium diethylamine-N-carbodithioate, piperidine-N-carbodithioate and several of its analogs, a number of other carbodithioates with two nonpolar groups on the nitrogen, and tetraethylthiuram disulfide, a prodrug of sodium diethylamine-N-carbodithioate and widely used in the treatment of alcoholism. The introduction of additional ionic or nonionic polar groups on the chelating molecule generally results in a loss of tyrpanocidal activity. Common commercially available chelating agents which exhibited no activity included D-penicillamine, meso-2,3-dimercaptosuccinic acid, and triethylenetetramine tetrahydrochloride. Dose-response data on the culture indicated that some of these compounds exhibited inhibition of Trypanosoma cruzi epimastigotes at concentrations as low as 0.625 microgram/mL. It is proposed that the mechanism of action of these compounds is based on their ability to interfere with the essential metal metabolism at intracellular sites of the epimastigote involving iron, copper, or zinc. The results also indicate that a certain degree of hydrophobicity may be necessary for the groups attached to the literal metal-bonding structure if the compounds are to successfully inhibit the epimastigotes of Trypanosoma cruzi. The development of antiprotozoal drugs which are chelating agents specifically designed to selectively disrupt the essential metal metabolism of Trypanosoma cruzi should furnish a new generation of drugs which can be used in the treatment of Chagas' disease.

Tuberculous enteritis: a case report.

Tuberculous enteritis is an unusual diagnosis in the United States. Because this entity is rare and the symptoms are not specific, the physician must have a high index of suspicion. We report the case of a young man with tuberculous involvement of the gastrointestinal tract who required surgical intervention for small bowel obstruction.

Successful surgical treatment of spontaneous coronary artery dissection.

To present a case of spontaneous coronary artery dissection (SCAD). Spontaneous coronary artery dissection is rare and often difficult to surgically repair. Additionally, diagnosis by coronary angiography is uncommon. We present a case of SCAD in a postpartum woman who underwent successful surgical correction of the left anterior descending artery. Such surgical intervention in cases similar to ours is critical for survival.

Recurrent pericarditis after thoracic surgery.

Acute pericarditis is a frequent complication after cardiac and/or thoracic surgery. Recurrent acute pericarditis with multiple episodes is an uncommon phenomenon, however. Patients typically have chest pain and/or pericardial inflammation as shown by electrocardiography and echocardiography. Treatment presents a clinical challenge due to the condition's rarity and lack of multicenter comparative treatment studies. Numerous therapeutic modalities, including nonsteroidal anti-inflammatory agents (NSAIDs), corticosteroids, immunosuppressants, and pericardiectomy, have been used without overwhelming evidence of a standard protocol. We report a case in which 32 episodes of recurrent acute pericarditis occurred, emphasizing the need for multicenter trials comparing therapeutic modalities in the future.

Volume determination of TEM specimens containing particles or precipitates.

The volume of thin foil specimens, which contain precipitate or other particles, viewed in the TEM is needed to determine particle density and spacing. It can be determined from the locations of the particles, measured using stereo pairs. A calculation that determines the volume between planes (not necessarily parallel or horizontal) that enclose the points is described. These planes will systematically underestimate the actual surface spacing and hence the volume, but a simple correction factor based on the number of points used in the fit can be used to estimate the actual volume. The method is tested, and its accuracy is evaluated using simulated data and applied to precipitate particles in creep-tested silicon carbide.

Successful treatment of an infant with Chromobacterium violaceum sepsis.

Chromobacterium violaceum sepsis, a rarely reported phenomenon, has a high mortality rate. We report a unique case of C. violaceum sepsis in an infant. A 4-month-old girl presented to our institution with fever, pustular skin lesions, and distended abdomen, as well as diminished activity and mental status. Radiological investigation revealed brain, lung, and hepatic abscesses. The infant was successfully treated with trimethoprim-sulfamethoxazole and ciprofloxacin.

Nail-patella syndrome: an incidental finding from abdominal discomfort.

An otherwise healthy 18-year-old woman had abdominal discomfort. Physical examination and laboratory studies were unremarkable, with the exception of nail dystrophy of the ulnar digits. An abdominal plain film revealed bilateral posterior iliac horns, pathognomonic of nail-patella syndrome. Additional radiographs showed hypoplastic patellas bilaterally. While glomerulonephritis occurs in 30% of patients with nail-patella syndrome, there was no evidence of renal involvement.

Idiopathic heterotopic ossification in the intensive care setting.

Heterotopic ossification is characterised by the periarticular deposition of ectopic bone. It typically occurs after trauma, neurogenic injury, or congenital causes. Idiopathic heterotopic ossification has been rarely reported. A patient who developed idiopathic heterotopic ossification in the intensive care unit without any known predisposing conditions is presented.

Isolated septic arthritis caused by penicillin-resistant Streptococcus pneumoniae.

Streptococcus pneumoniae is a common cause of infection in the pediatric population, as well as an important cause of septic arthritis. The increased prevalence of drug-resistant S pneumoniae in North America has renewed interest in the use of pneumococcal vaccines. We describe the case of a child with isolated acute septic arthritis caused by infection with penicillin-resistant S pneumoniae.

Cellular angiofibroma of the vulva.

BACKGROUND: The cellular angiofibroma is a benign mesenchymal neoplasm that clinically and histologically must be distinguished from biologically more aggressive lesions. It typically arises in women of late reproductive age and lends itself to cure by complete local excision. A report of an unusual case in a postmenopausal patient is presented. CASE: A 77-year-old woman presented with a painless vulvar mass that slowly enlarged over 3 years. Past history included a hysterectomy and bilateral salpingo-oophorectomy followed by estrogen replacement therapy. Surgical excision of the mass was performed and there is no evidence of recurrence 1 year postoperatively. Histopathologic examination revealed an admixture of hyalinized blood vessels and loose cellular stroma characteristic of a cellular angiofibroma. Immunohistochemical studies revealed stromal cell immunoreactivity for vimentin and CD34 and nonreactivity for desmin, actin, and S100 protein. The nuclei of the stromal cells demonstrated strong reactivity for estrogen and progesterone receptors. CONCLUSION: Mesenchymal lesions of the vulva and perineum include both benign and malignant neoplasms. The cellular angiofibroma is benign; however, other lesions including the aggressive angiomyxoma must be excluded when arriving at that diagnosis. The role of long-term estrogen therapy in the genesis of this tumor awaits further analysis.

Hereditary neuropathy with liability to pressure palsies mimicking multifocal compression neuropathy.

Hereditary neuropathy with liability to pressure palsies (HNPP) is a recurrent disorder of the peripheral nervous system characterized by reversible episodes of sensorimotor deficits after neural compression injuries. Also known as tomaculous neuropathy, HNPP is further characterized ultrastructurally by multiple focal thickenings (tomacula) of peripheral myelin and has an autosomal dominant inheritance. The neuropathology of HNPP includes a partial deletion encoding the peripheral myelin protein 22 (PMP-22) gene on chromosome 17, resulting in underexpression of PMP-22. We describe multiple compression mononeuropathies in an individual with HNPP and report neuropathologic findings in 2 clinically asymptomatic family members. Diagnosis was confirmed using pulsed-field gel electrophoresis. We believe that this diagnosis is clinically underappreciated by hand surgeons and should be considered in the differential diagnosis of patients with atypical presentations of compression neuropathies.