Factors influencing mercury exposure in Arctic-breeding shorebirds

Mercury (Hg) pollution remains a concern to Arctic ecosystems, due to long-range transport from southern industrial regions and melting permafrost and glaciers. The objective of this study was to identify intrinsic, extrinsic, and temporal factors influencing Hg concentrations in Arctic-breeding shorebirds and highlight regions and species at greatest risk of Hg exposure. We analyzed 1094 blood and 1384 feather samples from 12 shorebird species breeding at nine sites across the North American Arctic during 2012 and 2013. Blood Hg concentrations, which reflect Hg exposure in the local area in individual shorebirds: 1) ranged from 0.01-3.52 μg/g ww, with an overall mean of 0.30 ± 0.27 μg/g ww; 2) were influenced by species and study site, but not sampling year, with birds sampled near Utqiaġvik, AK, having the highest concentrations; and 3) were influenced by foraging habitat at some sites. Feather Hg concentrations, which reflected Hg exposure from the wintering grounds: 1) ranged from 0.07-12.14 μg/g fw in individuals, with an overall mean of 1.14 ± 1.18 μg/g fw; and 2) were influenced by species and year. Most Arctic-breeding shorebirds had blood and feather Hg concentrations at levels where no adverse effects of exposure were predicted, though some individuals sampled near Utqiaġvik had Hg levels that would be considered of concern. Overall, these data increase our understanding of how Hg is distributed in the various shorebird breeding areas of the Arctic, what factors predispose Arctic-breeding shorebirds to Hg exposure, and lay the foundation for future monitoring efforts.

ArcticBirdSounds: An open-access, multiyear, and detailed annotated dataset of bird songs and calls

Tracking biodiversity shifts is central to understanding past, present, and future global changes. Recent advances in bioacoustics and the low cost of high-quality automatic recorders are revolutionizing studies in biogeography and community and behavioral ecology with a robust assessment of phenology, species occurrence, and individual activity. This large volume of acoustic recordings has recently generated a plethora of datasets that can now be handled automatically, mostly via big data methods such as deep learning. These approaches need high-quality annotations to classify and detect recorded sounds efficiently. However, very few strongly annotated datasets-that is, with detailed information on start and end time of each vocalization-are openly accessible to the public. Moreover, these datasets mostly cover temperate species and are usually limited to a single year of recordings. Here, we present ArcticBirdSounds, the first open-access, multisite, and multiyear strongly annotated dataset of arctic bird vocalizations. ArcticBirdSounds offers 20 h of annotated recordings over 2 years (2018, 2019), taken from 15 distinct plots within six locations across the Arctic, from Alaska to Greenland. Recordings cover the arctic vertebrates' breeding period and are evenly spaced during the day; they capture most species breeding there with 12,933 temporal annotations in 49 classes of sounds. While these data can be used for many pressing ecological questions, it is also a unique resource for methodological development to help meet the challenges of fast ecosystem transformations such as those happening in the Arctic. All data, including audio files, annotation files, and companion spreadsheets, are available in an Open Science Framework repository published under a CC BY 4.0 License.

The (in)effectiveness of anticipatory vibrotactile cues in mitigating motion sickness

The introduction of (fully) automated vehicles has generated a re-interest in motion sickness, given that passengers suffer much more from motion sickness compared to car drivers. A suggested solution is to improve the anticipation of passive self-motion via cues that alert passengers of changes in the upcoming motion trajectory. We already know that auditory or visual cues can mitigate motion sickness. In this study, we used anticipatory vibrotactile cues that do not interfere with the (audio)visual tasks passengers may want to perform. We wanted to investigate (1) whether anticipatory vibrotactile cues mitigate motion sickness, and (2) whether the timing of the cue is of influence. We therefore exposed participants to four sessions on a linear sled with displacements unpredictable in motion onset. In three sessions, an anticipatory cue was presented 0.33, 1, or 3 s prior to the onset of forward motion. Using a new pre-registered measure, we quantified the reduction in motion sickness across multiple sickness scores in these sessions relative to a control session. Under the chosen experimental conditions, our results did not show a significant mitigation of motion sickness by the anticipatory vibrotactile cues, irrespective of their timing. Participants yet indicated that the cues were helpful. Considering that motion sickness is influenced by the unpredictability of displacements, vibrotactile cues may mitigate sickness when motions have more (unpredictable) variability than those studied here.

Climate-related range shifts in Arctic-breeding shorebirds

Aim

To test whether the occupancy of shorebirds has changed in the eastern Canadian Arctic, and whether these changes could indicate that shorebird distributions are shifting in response to long-term climate change.

Location

Foxe Basin and Rasmussen Lowlands, Nunavut, Canada.

Methods

We used a unique set of observations, made 25 years apart, using general linear models to test if there was a relationship between changes in shorebird species' occupancy and their species temperature Index, a simple version of a species climate envelope.

Results

Changes in occupancy and density varied widely across species, with some increasing and some decreasing. This is despite that overall population trends are known to be negative for all of these species based on surveys during migration. The changes in occupancy that we observed were positively related to the species temperature index, such that the warmer-breeding species appear to be moving into these regions, while colder-breeding species appear to be shifting out of the regions, likely northward.

Main Conclusions

Our results suggest that we should be concerned about declining breeding habitat availability for bird species whose current breeding ranges are centered on higher and colder latitudes.

Climate variables are not the dominant predictor of Arctic shorebird distributions

Competing theoretical perspectives about whether or not climate is the dominant factor influencing species' distributions at large spatial scales have important consequences when habitat suitability models are used to address conservation problems. In this study, we tested how much variables in addition to climate help to explain habitat suitability for Arctic-breeding shorebirds. To do this we model species occupancy using path analyses, which allow us to estimate the indirect effects of climate on other predictor variables, such as land cover. We also use deviance partitioning to quantify the total relative importance of climate versus additional predictors in explaining species occupancy. We found that individual land cover variables are often stronger predictors than the direct and indirect effects of climate combined. In models with both climate and additional variables, on average the additional variables accounted for 57% of the explained deviance, independent of shared effects with the climate variables. Our results support the idea that climate-only models may offer incomplete descriptions of current and future habitat suitability and can lead to incorrect conclusions about the size and location of suitable habitat. These conclusions could have important management implications for designating protected areas and assessing threats like climate change and human development.

The annual cycle for whimbrel populations using the Western Atlantic Flyway

Many long-distance migratory birds use habitats that are scattered across continents and confront hazards throughout the annual cycle that may be population-limiting. Identifying where and when populations spend their time is fundamental to effective management. We tracked 34 adult whimbrels (Numenius phaeopus) from two breeding populations (Mackenzie Delta and Hudson Bay) with satellite transmitters to document the structure of their annual cycles. The two populations differed in their use of migratory pathways and their seasonal schedules. Mackenzie Delta whimbrels made long (22,800 km) loop migrations with different autumn and spring routes. Hudson Bay whimbrels made shorter (17,500 km) and more direct migrations along the same route during autumn and spring. The two populations overlap on the winter grounds and within one spring staging area. Mackenzie Delta whimbrels left the breeding ground, arrived on winter grounds, left winter grounds and arrived on spring staging areas earlier compared to whimbrels from Hudson Bay. For both populations, migration speed was significantly higher during spring compared to autumn migration. Faster migration was achieved by having fewer and shorter stopovers en route. We identified five migratory staging areas including four that were used during autumn and two that were used during spring. Whimbrels tracked for multiple years had high (98%) fidelity to staging areas. We documented dozens of locations where birds stopped for short periods along nearly all migration routes. The consistent use of very few staging areas suggests that these areas are integral to the annual cycle of both populations and have high conservation value.

Sympatrically breeding congeneric seabirds (Stercorarius spp.) from Arctic Canada migrate to four oceans

Polar systems of avian migration remain unpredictable. For seabirds nesting in the Nearctic, it is often difficult to predict which of the world's oceans birds will migrate to after breeding. Here, we report on three related seabird species that migrated across four oceans following sympatric breeding at a central Canadian high Arctic nesting location. Using telemetry, we tracked pomarine jaeger (Stercorarius pomarinus, n = 1) across the Arctic Ocean to the western Pacific Ocean; parasitic jaeger (S. parasiticus, n = 4) to the western Atlantic Ocean, and long-tailed jaeger (S. longicaudus, n = 2) to the eastern Atlantic Ocean and western Indian Ocean. We also report on extensive nomadic movements over ocean during the postbreeding period (19,002 km) and over land and ocean during the prebreeding period (5578 km) by pomarine jaeger, an irruptive species whose full migrations and nomadic behavior have been a mystery. While the small sample sizes in our study limit the ability to make generalizable inferences, our results provide a key input to the knowledge of jaeger migrations. Understanding the routes and migratory divides of birds nesting in the Arctic region has implications for understanding both the glacial refugia of the past and the Anthropocene-driven changes in the future.

Predictors of invertebrate biomass and rate of advancement of invertebrate phenology across eight sites in the North American Arctic

Average annual temperatures in the Arctic increased by 2–3 °C during the second half of the twentieth century. Because shorebirds initiate northward migration to Arctic nesting sites based on cues at distant wintering grounds, climate-driven changes in the phenology of Arctic invertebrates may lead to a mismatch between the nutritional demands of shorebirds and the invertebrate prey essential for egg formation and subsequent chick survival. To explore the environmental drivers affecting invertebrate availability, we modeled the biomass of invertebrates captured in modified Malaise-pitfall traps over three summers at eight Arctic Shorebird Demographics Network sites as a function of accumulated degree-days and other weather variables. To assess climate-driven changes in invertebrate phenology, we used data from the nearest long-term weather stations to hindcast invertebrate availability over 63 summers, 1950–2012. Our results confirmed the importance of both accumulated and daily temperatures as predictors of invertebrate availability while also showing that wind speed negatively affected invertebrate availability at the majority of sites. Additionally, our results suggest that seasonal prey availability for Arctic shorebirds is occurring earlier and that the potential for trophic mismatch is greatest at the northernmost sites, where hindcast invertebrate phenology advanced by approximately 1–2.5 days per decade. Phenological mismatch could have long-term population-level effects on shorebird species that are unable to adjust their breeding schedules to the increasingly earlier invertebrate phenologies.

Ecological insights from three decades of animal movement tracking across a changing Arctic

The Arctic is entering a new ecological state, with alarming consequences for humanity. Animal-borne sensors offer a window into these changes. Although substantial animal tracking data from the Arctic and subarctic exist, most are difficult to discover and access. Here, we present the new Arctic Animal Movement Archive (AAMA), a growing collection of more than 200 standardized terrestrial and marine animal tracking studies from 1991 to the present. The AAMA supports public data discovery, preserves fundamental baseline data for the future, and facilitates efficient, collaborative data analysis. With AAMA-based case studies, we document climatic influences on the migration phenology of eagles, geographic differences in the adaptive response of caribou reproductive phenology to climate change, and species-specific changes in terrestrial mammal movement rates in response to increasing temperature.

Composition and Drivers of Gut Microbial Communities in Arctic-Breeding Shorebirds

Gut microbiota can have important effects on host health, but explanatory factors and pathways that determine gut microbial composition can differ among host lineages. In mammals, host phylogeny is one of the main drivers of gut microbiota, a result of vertical transfer of microbiota during birth. In birds, it is less clear what the drivers might be, but both phylogeny and environmental factors may play a role. We investigated host and environmental factors that underlie variation in gut microbiota composition in eight species of migratory shorebirds. We characterized bacterial communities from 375 fecal samples collected from adults of eight shorebird species captured at a network of nine breeding sites in the Arctic and sub-Arctic ecoregions of North America, by sequencing the V4 region of the bacterial 16S ribosomal RNA gene. Firmicutes (55.4%), Proteobacteria (13.8%), Fusobacteria (10.2%), and Bacteroidetes (8.1%) dominated the gut microbiota of adult shorebirds. Breeding location was the main driver of variation in gut microbiota of breeding shorebirds (R² = 11.6%), followed by shorebird host species (R² = 1.8%), and sampling year (R² = 0.9%), but most variation remained unexplained. Site variation resulted from differences in the core bacterial taxa, whereas rare, low-abundance bacteria drove host species variation. Our study is the first to highlight a greater importance of local environment than phylogeny as a driver of gut microbiota composition in wild, migratory birds under natural conditions.

Long-distance migratory shorebirds travel faster towards their breeding grounds, but fly faster post-breeding

Long-distance migrants are assumed to be more time-limited during the pre-breeding season compared to the post-breeding season. Although breeding-related time constraints may be absent post-breeding, additional factors such as predation risk could lead to time constraints that were previously underestimated. By using an automated radio telemetry system, we compared pre- and post-breeding movements of long-distance migrant shorebirds on a continent-wide scale. From 2014 to 2016, we deployed radio transmitters on 1,937 individuals of 4 shorebird species at 13 sites distributed across North America. Following theoretical predictions, all species migrated faster during the pre-breeding season, compared to the post-breeding season. These differences in migration speed between seasons were attributable primarily to longer stopover durations in the post-breeding season. In contrast, and counter to our expectations, all species had higher airspeeds during the post-breeding season, even after accounting for seasonal differences in wind. Arriving at the breeding grounds in good body condition is beneficial for survival and reproductive success and this energetic constraint might explain why airspeeds are not maximised in the pre-breeding season. We show that the higher airspeeds in the post-breeding season precede a wave of avian predators, which could suggest that migrant shorebirds show predation-minimizing behaviour during the post-breeding season. Our results reaffirm the important role of time constraints during northward migration and suggest that both energy and predation-risk constrain migratory behaviour during the post-breeding season.

Comment on "Global pattern of nest predation is disrupted by climate change in shorebirds"

Kubelka et al (Reports, 9 November 2018, p. 680) claim that climate change has disrupted patterns of nest predation in shorebirds. They report that predation rates have increased since the 1950s, especially in the Arctic. We describe methodological problems with their analyses and argue that there is no solid statistical support for their claims.

Long-term continental changes in wing length, but not bill length, of a long-distance migratory shorebird

We compiled a >50‐year record of morphometrics for semipalmated sandpipers (Calidris pusilla), a shorebird species with a Nearctic breeding distribution and intercontinental migration to South America. Our data included >57,000 individuals captured 1972–2015 at five breeding locations and three major stopover sites, plus 139 museum specimens collected in earlier decades. Wing length increased by ca. 1.5 mm (>1%) prior to 1980, followed by a decrease of 3.85 mm (nearly 4%) over the subsequent 35 years. This can account for previously reported changes in metrics at a migratory stopover site from 1985 to 2006. Wing length decreased at a rate of 1,098 darwins, or 0.176 haldanes, within the ranges of other field studies of phenotypic change. Bill length, in contrast, showed no consistent change over the full period of our study. Decreased body size as a universal response of animal populations to climate warming, and several other potential mechanisms, are unable to account for the increasing and decreasing wing length pattern observed. We propose that the post‐WWII near‐extirpation of falcon populations and their post‐1973 recovery driven by the widespread use and subsequent limitation on DDT in North America selected initially for greater flight efficiency and latterly for greater agility. This predation danger hypothesis accounts for many features of the morphometric data and deserves further investigation in this and other species.

Effects of geolocators on hatching success, return rates, breeding movements, and change in body mass in 16 species of Arctic-breeding shorebirds

BACKGROUND

Geolocators are useful for tracking movements of long-distance migrants, but potential negative effects on birds have not been well studied. We tested for effects of geolocators (0.8-2.0 g total, representing 0.1-3.9 % of mean body mass) on 16 species of migratory shorebirds, including five species with 2-4 subspecies each for a total of 23 study taxa. Study species spanned a range of body sizes (26-1091 g) and eight genera, and were tagged at 23 breeding and eight nonbreeding sites. We compared breeding performance and return rates of birds with geolocators to control groups while controlling for potential confounding variables.

RESULTS

We detected negative effects of tags for three small-bodied species. Geolocators reduced annual return rates for two of 23 taxa: by 63 % for semipalmated sandpipers and by 43 % for the arcticola subspecies of dunlin. High resighting effort for geolocator birds could have masked additional negative effects. Geolocators were more likely to negatively affect return rates if the total mass of geolocators and color markers was 2.5-5.8 % of body mass than if tags were 0.3-2.3 % of body mass. Carrying a geolocator reduced nest success by 42 % for semipalmated sandpipers and tripled the probability of partial clutch failure in semipalmated and western sandpipers. Geolocators mounted perpendicular to the leg on a flag had stronger negative effects on nest success than geolocators mounted parallel to the leg on a band. However, parallel-band geolocators were more likely to reduce return rates and cause injuries to the leg. No effects of geolocators were found on breeding movements or changes in body mass. Among-site variation in geolocator effect size was high, suggesting that local factors were important.

CONCLUSIONS

Negative effects of geolocators occurred only for three of the smallest species in our dataset, but were substantial when present. Future studies could mitigate impacts of tags by reducing protruding parts and minimizing use of additional markers. Investigators could maximize recovery of tags by strategically deploying geolocators on males, previously marked individuals, and successful breeders, though targeting subsets of a population could bias the resulting migratory movement data in some species.

Family involvement with the diabetes regimen in young people: the role of adolescent depressive symptoms

AIMS

In young people with Type 1 diabetes, depressive symptoms and shared responsibility for management of diabetes impact upon diabetes management and control. However, the simultaneous effects of both depressive symptoms and parental involvement on diabetes self-care and glycaemic control have not been examined. Thus, the aim of the current study was to examine the relationships between parental involvement and adolescent depressive symptoms in predicting blood glucose monitoring and glycaemic control.

METHODS

One hundred and fifty young people with Type 1 diabetes (mean age 15.3 years) and their parents completed responsibility sharing and depressive symptom assessments, meter assessment of blood glucose monitoring and HbA(1c) at baseline and then 6, 12 and 18 months.

RESULTS

Parental involvement affected HbA1c through blood glucose monitoring only at low levels of adolescent depressive symptoms (score ≤ 6), which made up only 20% of the sample. In the presence of more depressive symptoms, parental involvement no longer was related to HbA1c through blood glucose monitoring. This was the relationship in the majority of the sample (80%).

CONCLUSIONS

While most young people in this sample are not showing evidence of high levels of depressive symptoms, even modest levels of distress interfere with parental involvement in diabetes management. By addressing adolescent depressive symptoms, interventions promoting parental involvement in these families may be more effective.

Scorecard endoscopy: a pilot study to assess basic skills in trainees for upper gastrointestinal endoscopy

BACKGROUND

The development of training models and structured training courses for endoscopic techniques provides practical experience. To assess individual performance and progress in this training we developed and tested a scorecard system.

METHODS

Three test groups were compared: group 1, ten physicians without previous endoscopic experience; group 2, ten students, without endoscopic experience; group 3, a control group of experienced endoscopists. Groups 1 and 2 underwent 1 week of training with a theoretical introduction and practical demonstrations. They were assessed by the scorecard daily by an experienced tutor. The individual scores and learning curves of the two beginner groups were compared with those of the expert group using a biosimulation model was used.

RESULTS

Each participant improved significantly during the 1-week course. Mean scores on the first day in groups 1-3 were, respectively, 26.7+/-10.7, 33.4+/-5.3, and 72.0+/-5.8, and on day 6 they were 62.2+/-6.6, 63.4+/-7.6, and 86.6+/-4.3. The difference between group 3 and the other two groups was significant but not that between groups 1 and 2.

CONCLUSIONS

Training in endoscopy can be assessed using our training model and our scorecard protocol, which distinguishes between various levels of experience. In physicians beginning in the field of gastrointestinal endoscopy this approach could help to reduce risks to patients, shorten learning curves, and exclude unskilled individuals from further fruitless interventions.

Sertraline treatment of posttraumatic stress disorder: results of 24 weeks of open-label continuation treatment

BACKGROUND

Posttraumatic stress disorder (PTSD) is typically associated with a high degree of chronicity, comorbidity, and psychosocial disability. The efficacy of sertraline in the acute treatment of PTSD has been confirmed based on the results of 2 large, placebo-controlled studies, but almost no prospective long-term treatment studies have been reported.

METHOD

One hundred twenty-eight patients who completed 12 weeks of double-blind, placebo-controlled, acute-phase treatment for DSM-III-R-defined PTSD with sertraline were continued into a 24-week open-label continuation phase. Efficacy was evaluated using the endpoint change in the 17-item Clinician Administered PTSD Scale Part 2 (CAPS-2) severity score, the 15-item patient-rated Impact of Event Scale, and the Clinical Global Impressions-Improvement and -Severity of Illness scales as primary outcome measures. Treatment response was defined as > or =30% decrease in the CAPS-2 total severity score (compared with acute-phase baseline score) and a Clinical Global Impressions-Improvement score of 1 or 2.

RESULTS

Ninety-two percent of acute-phase responders maintained their response during the full 6 months of continuation treatment. In addition, 54% of acute-phase nonresponders converted to responder status during continuation therapy. Over the 36-week course of acute and continuation therapy, 20% to 25% of the improvement in the CAPS-2 severity score occurred during the continuation phase. Sertraline was well tolerated, with 8.6% of patients discontinuing due to adverse events. A high pretreatment CAPS-2 score (> 75) predicted a longer time to response and a greater likelihood that response occurred after 12 weeks of acute treatment.

CONCLUSION

The acute efficacy of sertraline is sustained in the vast majority of patients, and at least half of nonresponders to acute treatment will eventually respond to continued treatment.

Interleukin-2-based immunotherapy for the treatment of metastatic renal cell carcinoma: an analysis of 203 consecutively treated patients

PURPOSE

This article analyzes the long-term results of 203 consecutive patients with metastatic renal cell carcinoma who were treated with various recombinant interleukin-2 (rIL-2) -based immunotherapy regimens, and describes factors that may influence response to therapy and long-term survival.

PATIENTS AND METHODS

The response and survival of 203 patients with metastatic renal cell carcinoma treated consecutively between July 1987 and October 1995 at the UCLA Medical Center Kidney Cancer Program with rIL-2-based immunotherapy were analyzed. Patients were divided into four groups: (1) no prior nephrectomy (n = 24), (2) nephrectomy > 6 months prior to rIL-2 therapy (n = 76), (3) nephrectomy < or = 6 months prior to rIL-2 therapy (n = 47), and (4) nephrectomy followed by treatment with rIL-2 and tumor-infiltrating lymphocytes +/- interferon-alpha (n = 56). Response and survival for each of these patient groups and survival per response to therapy were compared.

RESULTS

The overall median survival for all patients was 18 months, and survival at 1, 2, and 3 years after therapy was 61%, 40%, and 31% percent, respectively. A total of 12 patients (6%) achieved a complete response, and all were alive at 3 years. Of 36 patients (18%) who achieved a partial response and 41 patients (20%) with stable disease, 3-year survival was 37% and 50%, respectively. The survival of patients with a partial response or stable disease was significantly better than that of patients who exhibited progressive disease. Patients with nephrectomy > 6 months prior to rIL-2 therapy had a 46% 3-year survival rate, compared with a 9% 3-year survival rate for patients with nephrectomy < or = 6 months prior to rIL-2 therapy and a 4% 3-year survival rate for patients with no nephrectomy. Patients treated with tumor-infiltrating lymphocytes had a 38% 3-year survival rate, which was also significantly better than patients treated with nephrectomy < or = 6 months prior to rIL-2 therapy or with no nephrectomy.

CONCLUSION

This analysis demonstrated that rIL-2-based therapy offers a significant survival benefit to patients with advanced metastatic renal cell carcinoma, compared with historical controls. Furthermore, we have shown that nephrectomy > 6 months prior to rIL-2 therapy and nephrectomy followed by treatment with tumor-infiltrating lymphocytes/rIL-2 +/- interferon-alpha was associated with the greatest survival benefit. Tumor response to rIL-2-based therapy and time from nephrectomy to treatment were the most important predictors of survival. Randomized studies in a large group of patients are needed to confirm these observations.

Distinct association of transferrin receptor with HLA class I molecules on HUT-102B and JY cells

The topological relationship of transferrin receptor (TfR) has been studied relative to the heavy and light chains of the HLA class I molecules, class II molecules, interleukin-2 receptor alpha-chain and ICAM-1 molecule in the plasma membrane of HUT-102B2 T and JY B lymphoblastoid cell lines using the flow cytometric fluorescence energy transfer technique (FCET). The effect of different growing conditions (logarithmic and plateau phases) on the relative surface density of the receptors and the lateral organization of the TfR was also studied. The TfR showed a high degree of self-association on the surface of both cell lines regardless of the growing phase. TfR was in close vicinity to HLA class I heavy and light chains on HUT-102B cells in both plateau and logarithmic phases, while it was not associated with HLA class I on the surface of JY cells. HLA class II molecules form a cluster with TfR on HUT-102B cells, while only a modest association was found on JY cells, and only in the logarithmic phase. The possible explanation of this distinct association and a two dimensional model of the antigen and receptor distributions are presented in this paper.

Characterization of infectious molecular clones of equine infectious anaemia virus

We have recovered five infectious molecular clones of the lentivirus equine infectious anaemia virus (EIAV). The clones were recovered from fetal equine kidney (FEK) cells infected with a virulent, cell culture-adapted virus stock (designated PV) and have been characterized at a molecular level. Each clone has unique envelope and long terminal repeat (LTR) sequences. We further investigated LTR sequence variation in the PV stock using PCR amplification to obtain additional LTR clones from infected FEK cells and from peripheral blood mononuclear cells (PBMCs) from animals experimentally infected with PV. Sequence analysis of resulting clones indicates a selection for different LTR populations in pony PBMCs compared to FEK cells. Finally, we observed that the cloned EIAV proviruses did not remain infectious when maintained in a derivative of pBR322. However, two proviruses have been stably maintained in a low copy number vector (pLG338-SPORT).

Physostigmine-induced epinephrine release in patients with affective disorder

Infusion of the cholinomimetic drug physostigmine led to profound increases in serum epinephrine levels and slight increases in serum norepinephrine levels among 38 patients with affective disorder and 22 control subjects. Preliminary results suggest that physostigmine may induce relatively blunted increases in serum epinephrine levels in patients with affective disorders.

The antiarrhythmic effect of PGE2 on premature ventricular beats (PVBs) in man

In 10 patients with premature ventricular beats (PVBs) we investigated the influence of PGE2 infusion on ventricular arrhythmias, arterial blood pressure, heart rate and systolic time intervals. An infusion of PGE2 in doses of 0.01, 0.02 and 0.04 microgram/kg/min, each for 10 min, did not change the blood pressure, heart rate and systolic time intervals. The incidence of PVBs decreased in a dose-dependent manner in 7 out of 10 patients, and in two of them PVBs were absolutely abolished. In one patient the incidence of PVBs was reduced dose independently, and in two patients at the beginning of infusion of PGE2 the incidence of PVBs was reduced, but the incidence of PVBs increased again although the infusion dose was doubled. In all patients the incidence of PVBs increased again when the infusion of PGE2 was stopped. Our findings demonstrate that PGE2 has antiarrhythmic properties in man.

Influence of acetylsalicylic acid on acute circulatory effects of the beta-blocking agents pindolol and propranolol in humans

In ten hospitalized, hypertensive male patients (WHO stage I or II) an acetylsalicylic acid (ASA) pretreatment (p.o. 5.0 g/24 h) prevented the acute blood pressure (BP) lowering effect of pindolol (1 mg i.v.) as compared with a placebo pretreatment. Similarly in six other hospitalized male patients (four normotensive, two slightly hypertensive) a single dose of ASA (1.0 or 1.5 g orally), which alone tended to raise the BP, reduced the decrease in systolic BP and led to an increase in diastolic BP following propranolol (5 mg i.v.). The ASA pretreatment did not affect the decrease in heart rate and cardiac contractility (measured by systolic time intervals) after the application of pindolol and propranolol, respectively. In conformity with data in the literature, the results suggest a possible connection between endogenous prostaglandins and the hypotensive, but not negative chronotropic and inotropic activity of the beta-blocking agents investigated.

Patent ductus arteriosus in preterm infants with idiopathic respiratory distress syndrome. Radiographic and echocardiographic evaluation

Clinical, radiographic, echocardiographic and operative findings were evaluated in 55 preterm infants with idiopathic respiratory distress syndrome (IRDS) complicated by patent ductus arteriosus (PDA). Pulmonary plethora was detected prior to age seven days in 52 infants, and prior to murmur detection in 42 infants. In those with large shunts, only 35% had cardiomegaly while 78% had a significant increase in cardiothoracic ratio (C/T) on sequential radiographs. Moreover, within 48 hours after ligation, 91% of infants had a significant decrease in C/T. Echocardiographic left atrial to aortic ratio (LA/Ao) was elevated in 71% with large shunts. In one patient with a large shunt there was neither a sequential increase in C/T nor an increased LA/Ao. Severity of left-to-right shunting across a PDA in the newborn was reliably gauged by combined radiographic and echocardiographic evaluation. Either modality alone failed to reflect the presence of a large volume shunt in a number of infants.

Comparative study of the cardiac and peripheral vascular effects of strophantin K and lanatoside C in coronary heart disease

The effects of intravenous strophanthin K (0.125 and 0.25 MG) and lanatoside C (0.4, 0.8 and 1.6 mg) on systolic time intervals (STI) and impedance plethysmographic (IP)P values were studied in ten patients with compensated coronary heart disease. The heart rate decreased significantly during a two-hour study in the lying position after both glycosides and placebo; the systemic blood pressure remained unchanged. Electromechanical systole (QS2), left ventricular ejection time (LVET) and preejection period (PEP), corrected for heart rate (QS2I, LVETI, PEPI), showed no change after placebo. The glycosides caused no change in LVETI. QS2I was significantly shortened only after lanatoside C 1.6 mg. PEPI and ICT were significantly shortened by both doses of strophanthin K and lanatoside C; the effects were dose-related. Taking into consideration the effects of cardiac glycosides on STI, use of the index ICT/QS1, the quotient of isovolumic contraction time and electro-mechanical delay, is proposed, because it showed quite sensitively the increase in myocardial contractility after digitalis. The effect of strophanthin K could be detected 10 minutes, and that of lanatoside C 30-40 minutes, after injection. The amplitude of the IP curve and the relative pulse volume showed positive and negative changes without any trend after administration of placebo or glycoside. The data suggests that the usual therapeutic doses of these cardiac glycosides do not cause significant changes in the peripheral circulation in patients with compensated coronary heart disease, but their action on STI is quite marked, showing a positive inotropic effect.