Temporal variability of a protected multispecific tropical seagrass meadow in response to environmental change.

In a changing environment, there is an increasing interest to monitor ecosystems to understand their responses to environmental change. Seagrass meadows are highly important ecosystems that are under constant pressure from human activities and climate impacts, with marked declines observed worldwide. Despite increasing efforts, monitoring of multispecific tropical seagrass meadows is scarce, particularly in low-income regions. Based on data from a monitoring programme in a marine protected area in Zanzibar (Tanzania), we assessed temporal changes in seagrass cover and species composition during a 10-year period in relation to local variability in environmental variables. We observed a strong, gradual decline in seagrass cover and changes in species composition, followed by a period of recovery. However, the timing and length of these temporal patterns varied in space (between transects). Multiple environmental variables-cloud cover, temperature, storm occurrence, sunspot activity, and tidal amplitude and height-influenced seagrass cover, although only to a minor extent, suggesting that the monitored seagrass meadow may be influenced by other unmeasured factors (e.g. water currents and sediment movement). Our results show that seagrass meadows can be highly dynamic at small (10-50 m) spatial scales, even in the absence of major local anthropogenic impacts. Our findings suggest that high-resolution monitoring programmes can be highly valuable for the detection of temporal changes in multispecific seagrass meadows; however, to understand the causes of change, there is a need of long-term (> 10 years) data series that include direct measurements of environmental variables and extreme events.

ARCTIC CHANGE AND POSSIBLE INFLUENCE ON MID-LATITUDE CLIMATE AND WEATHER: A US CLIVAR White Paper.

The Arctic has warmed more than twice as fast as the global average since the mid 20th century, a phenomenon known as Arctic amplification (AA). These profound changes to the Arctic system have coincided with a period of ostensibly more frequent events of extreme weather across the Northern Hemisphere (NH) mid-latitudes, including extreme heat and rainfall events and recent severe winters. Though winter temperatures have generally warmed since 1960 over mid-to-high latitudes, the acceleration in the rate of warming at high-latitudes, relative to the rest of the NH, started approximately in 1990. Trends since 1990 show cooling over the NH continents, especially in Northern Eurasia. The possible link between Arctic change and mid-latitude climate and weather has spurred a rush of new observational and modeling studies. A number of workshops held during 2013-2014 have helped frame the problem and have called for continuing and enhancing efforts for improving our understanding of Arctic-mid-latitude linkages and its attribution to the occurrence of extreme climate and weather events. Although these workshops have outlined some of the major challenges and provided broad recommendations, further efforts are needed to synthesize the diversified research results to identify where community consensus and gaps exist. Building upon findings and recommendations of the previous workshops, the US CLIVAR Working Group on Arctic Change and Possible Influence on Mid-latitude Climate and Weather convened an international workshop at Georgetown University in Washington, DC, on February 1-3, 2017. Experts in the fields of atmosphere, ocean, and cryosphere sciences assembled to assess the rapidly evolving state of understanding, identify consensus on knowledge and gaps in research, and develop specific actions to accelerate progress within the research community. With more than 100 participants, the workshop was the largest and most comprehensive gathering of climate scientists to address the topic to date. In this white paper, we synthesize and discuss outcomes from this workshop and activities involving many of the working group members. WORKSHOP FINDINGS: Rapid Arctic change - Emergence of new forcing (external and internal) of atmospheric circulation: Rapid Arctic change is evident in the observations and is simulated and projected by global climate models. AA has been attributed to sea ice and snow decline (regionally and seasonally varying). However this cannot explain why AA is greatest in winter and weakest in summer. It was argued at the workshop that other factors can also greatly contribute to AA including: increased downwelling longwave radiation from greenhouse gases (including greater water vapor concentrations from local and remote sources); increasing ocean heat content, due to local and remote processes; regional and hemispheric atmospheric circulation changes; increased poleward heat transport in the atmosphere and ocean; and cloud radiative forcing. In particular, there is emerging observational evidence that an enhanced poleward transport of sensible and latent heat plays a very important role in the AA of the recent decades, and that this enhancement is mostly fueled by changes in the atmospheric circulation. We concluded that our understanding of AA is incomplete, especially the relative contributions from the different radiative, thermodynamic, and dynamic processes.Arctic mid-latitude linkages - Focusing on seasonal and regional linkages and addressing sources of inconsistency and uncertainty among studies: The topic of Arctic mid-latitude linkages is controversial and was vigorously debated at the workshop. However, we concluded that rapid Arctic change is contributing to changes in mid-latitude climate and weather, as well as the occurrence of extreme events. But how significant the contribution is and what mechanisms are responsible are less well understood. Based on the synthesis efforts of observational and modeling studies, we identified a list of proposed physical processes or mechanisms that may play important roles in linking Arctic change to mid-latitude climate and weather. The list, ordered from high to low confidence, includes: increasing geopotential thickness over the polar cap; weakening of the thermal wind; modulating stratosphere-troposphere coupling; exciting anomalous planetary waves or stationary Rossby wave trains in winter and modulating transient synoptic waves in summer; altering storm tracks and behavior of blockings; and increasing frequency of occurrence of summer wave resonance. The pathway considered most robust is the propagation of planetary/Rossby waves excited by the diminished Barents-Kara sea ice, contributing to a northwestward expansion and intensification of the Siberian high leading to cold Eurasian winters. OPPORTUNITIES AND RECOMMENDATIONS: An important goal of the workshop was achieved: to hasten progress towards consensus understanding and identification of knowledge gaps. Based on the workshop findings, we identify specific opportunities to utilize observations and models, particularly a combination of them, to enable and accelerate progress in determining the mechanisms of rapid Arctic change and its mid-latitude linkages.Observations: Due to the remoteness and harsh environmental conditions of the Arctic, in situ observational time series are highly limited spatially and temporally in the region.Six recommendations to expand approaches using observational datasets and analyses of Arctic change and mid-latitude linkages include: Synthesize new Arctic observations;Create physically-based sea ice-ocean surface forcing datasets;Systematically employ proven and new metrics;Analyze paleoclimate data and new longer observational datasets;Utilize new observational analysis methods that extend beyond correlative relationships; andConsider both established and new theories of atmospheric and oceanic dynamics to interpret and guide observational and modeling studies.Model experiments: We acknowledge that models provide the primary tool for gaining a mechanistic understanding of variability and change in the Arctic and at mid-latitudes. Coordinated modeling studies should include approaches using a hierarchy of models from conceptual, simple component, or coupled models to complex atmospheric climate models or fully coupled Earth system models. We further recommend to force dynamical models with consistent boundary forcings.Three recommendations to advance modeling and synthesis understanding of Arctic change and mid-latitude linkages include: Establish a Modeling Task Force to plan protocols, forcing, and output parameters for coordinated modeling experiments (Polar Amplification Model Intercomparison Project; PAMIP);Furnish experiment datasets to the community through open access (via Earth System Grid); andPromote analysis within the community of the coordinated modeling experiments to understand mechanisms for AA and to further understand pathways for Arctic mid-latitude linkages.

A comparison of growing season indices for the Greater Baltic Area.

Predictions of the effects of global warming suggest that climate change may have large impacts on ecosystems. The length of the growing season is predicted to increase in response to increasing global temperatures. The object of this study was to evaluate different indices used for calculating the thermal growing season for the Greater Baltic Area (GBA). We included established indices of growing season start, end and length, as well as new and modified indices. Based on the results, the GBA can be divided into a maritime western part and a more continental eastern part, with the western part reacting more sensitively to the use of different indices. The eastern part is more stable, but even here the index-to-index differences are large. It was found that including or excluding a frost criterion had a significant influence on the initiation of the growing season in the western, maritime, parts of the GBA. Frost has not the same importance for the end of the growing season. However, some end indices can result in a "never ending" growing season. When looking at twentieth century trends in growing season parameters, it was found that, when averaged over the whole GBA, there was little difference in trends depending on the indices used. The general mean trend in the GBA for the twentieth century discloses an earlier onset of c. 12 days, a delayed end of c. 8 days and consequently a lengthening of the growing season of about 20 days.

Comparison of some criteria for diagnosing a myocardial infarction after aorto-coronary bypass grafting (CABG).

The incidence of myocardial infarction during a 1-year follow-up period after coronary bypass surgery (CABG), i.e. a recent myocardial infarction (RMI), was studied in 86 patients. Different criteria for the diagnosis of a RMI were compared. Clinical observation, including ECG and serum enzyme analysis, diagnosed RMI in 8% of patients. Specific ECG changes indicating RMI (ECGsp) occurred in 12% of cases, and if less specific ECG changes were also taken into account (ECGsp+nonsp) RMI was found in 30% of cases. Asynergy, detected by two-plane ventriculography, indicated RMI in 24% of the patients, and was probably the most valid of the criteria examined. The differences in diagnostic accuracy of the various criteria highlight the importance of defining diagnostic criteria.

Hereditary myopathy with lactic acidosis, succinate dehydrogenase and aconitase deficiency in northern Sweden: a genealogical study.

A hereditary myopathy with lactic acidosis during physical exercise, low physical work capacity, and paroxysmal myoglobinuria (HML), called "Myopathy with deficiency of succinate dehydrogenase and aconitase" (McKusick 255125) has been described in 19 members of nine families who lived in two geographically separate areas in northern Sweden. By using the unique Swedish historical archives, including Catechetical Meeting Records from a number of northern Swedish parishes, it has been possible to trace ancestors of the nine families including all known 19 cases back in time to some key couples, who lived up to 300 years ago (that is seven to ten generations). No common single couple or common links between families in the past was found in these registers as a support for a single or several mutations that had developed far back in time. The mode of inheritance in this family is most likely autosomal recessive. This material will be used for the chromosomal localisation of the gene.

Effects of digitalis, anti-anginal drugs and arterial hypertension on the relationships between exercise ECG and angiocardiographic variables and on the diagnostic accuracy of exercise ECG in patients with coronary heart disease.

We have previously found a statistically significant correlation between some exercise ECG variables and angiocardiographic scores used to evaluate the extent and type of coronary heart disease (CHD). In the present study we examined the effects of digitalis, beta-adrenergic blockers, slow release nitrates, calcium channel blockers, presence of arterial hypertension (AHT), and angiocardiographic changes on the exercise ECG variables. The effects of drugs and AHT were small as compared to the effects of the angiocardiographically detected pathological changes caused by the CHD. Sensitivity and specificity of the exercise ECG ST criteria in identifying patients with an angiocardiographic criterion indicating coronary insufficiency were not much different in the whole group and in the subsets with AHT or medication with digitalis and anti-anginal drugs.

Relationships between exercise ECG and angiocardiographic indices of coronary insufficiency and myocardial fibrosis in coronary heart disease.

Patients with coronary heart disease were examined with exercise ECG and angiocardiography. Maximum work capacity expressed as a percentage of the predicted normal exercise tolerance (Wmax%) was significantly associated with the angiocardiographic score of the myocardial mass subserved by obstructed coronary arteries (MCOS). Variables related to myocardial fibrosis (MF) such as post infarction ECG signs, the left ventricular wall motion score (LVMS) and the ejection fraction of the left ventricle (LVEF) correlated significantly as did variables related to reversible myocardial ischaemia or coronary insufficiency (CI), such as ST depression during exercise (STdepr), ST/W and ST/HR indices, effort angina (EA/W) index, the extent of collaterals (CollS), and 'MCOS-LVMS'. MF variables correlated weakly with CI variables. Wmax% covariated with the variables related to both CI and MF, and most closely with MCOS. Discrepancies between results of exercise ECG and angiocardiography have to some extent been overcome by comparing appropriate parameters.

Oesophageal dysfunction in familial amyloidosis with polyneuropathy.

Sixteen patients with familial amyloidosis and polyneuropathy (FAP) and 14 health subjects underwent oesophageal manometry. Six of the patients had a severe oesophageal dysmotility with almost completely abolished propulsive pressure waves on swallowing in the lower 2/3 of the oesophagus. Ten patients had moderate dysfunction with reduced propulsive pressure wave amplitudes. Neostigmine increased the pressure wave amplitudes in healthy subjects but less so in the FAP patients. Scopolamine (Scopyl)-terbutaline (Bricanyl) almost abolished the propulsive pressure waves in healthy subjects and all patients in the lower 2/3 of the esophagus. Oesophageal distensibility, tested by inflating a rubber balloon in the oesophagus, was similar in FAP patients and healthy subjects. Thus, it is unlikely that amyloid deposits in the mucosal wall increased the oesophageal stiffness. An autonomic, predominantly vagal, denervation probably explains the disturbed function.

Dependence of maximum performance time on work intensity in patients with a hereditary myopathy with succinate dehydrogenase deficiency.

Patients with a hereditary mitochondrial myopathy with succinate dehydrogenase (SDH) deficiency and abnormal lactacidosis during physical exercise have a low work capacity when exercising for about 10-15 min. Their maximum voluntary muscular strength is fairly normal. The relationship between the time (t) and a constant workload (N) that a healthy subject can maximally sustain can be expressed as: log t = beta + alpha log N. For normal subjects the constant alpha is approximately -5 and the constant beta has a large interindividual variation. Of four myopathy patients alpha was determined from two or three maximum bicycle exercise tests of different duration (including ramp- and steady-state tests using a new application of the method of adding submaximal loads to the final maximum workload). The value of alpha varied between -1.0 and -1.81 and beta had low values, both significantly different from those of healthy subjects. The alpha values explain the divergent results that may be obtained with different types of exercise tests in some of these patients, i.e. a normal or moderately reduced capacity in exercise tests of short duration (for example a short Tornvall or a ramp type of test) and a very low exercise capacity in tests of longer duration (for example a steady state type of test with workloads chosen to allow at least two loads). The low absolute value of alpha may be related to the abnormally increased anaerobic metabolism of these patients during exercise, caused by the SDH deficiency.

Reaction of patients with effort angina to cold exposure during exercise.

An attempt has been made to characterize so-called "responders" to cold among patients with effort angina. Forty-nine such patients, unselected with regard to their history of reactions to cold, who showed ST depressions during and after exercise, were examined. They worked on a bicycle ergometer close to their maximum capacity, Wmax, at room temperature (about 23 degrees C) and in a cold room (-15 degrees C). ECG was recorded and a rating scale was used to estimate the perceived exertion during exercise (RPE). The presence of angina pectoris during exercise and its duration after exercise was recorded by an EA score. An EA/W index was used to estimate the severity of the effort angina. In the whole group, the mean Wmax decreased and the mean ST depressions, RPE, and EA/W index (but not EA score) increased on exposure to cold. The changes in these variables due to exposure to cold were all associated (but not the EA score). Criteria requiring a decrease in Wmax or increase in ST depression, RPE or EA/W index on cold exposure identified 53 to 63 percent of the patients. By combining the criteria, the number of patients, who were identified, decreased. If all the criteria were applied, about 30 percent of the patients were identified as "responders" to cold and they showed the most marked responses. Thus several exercise ECG test parameters may be used to reliably define "responders" to cold exposure. This may enhance future studies of the response reaction.

Low succinate dehydrogenase (SDH) activity in a patient with a hereditary myopathy with paroxysmal myoglobinuria.

An unusual hereditary myopathy with paroxysmal myoglobinuria has been described previously. We have studied muscle biopsy specimens taken before and after exercise to exhaustion (24 min at 20-25 W) in a young woman with this condition. Marked glycogenolysis with lactate production and marked phosphagen breakdown (ATP + CP) were observed after exercise, and almost all type I fibres were found to be depleted of glycogen. Succinate dehydrogenase (SDH) activity was low, while the activities of 3-OH-acyl-CoA-dehydrogenase, phosphofructokinase, phosphorylase and lactate dehydrogenase were normal. On electron microscopy, the mitochondria showed abnormalities typical of mitochondrial myopathy. The findings in our patient suggest a limitation of mitochondrial function, probably related to SDH in the tricarboxylic acid cycle and complex II in the electron transport chain. This may explain the inability of ATP regeneration to keep pace with ATP utilization during exercise. Other metabolic defects may coexist.

Clinical physiology: an accepted branch of physiology.

Clinical physiology is a branch of physiology particularly dealing with functional disturbances in disease (pathophysiology) and the integrated function of the human body in disease against the background of normal function in healthy subjects, suitable physiological methods for the study of patients--particularly for diagnostic purposes--as well as for research, and the education of medical students and laboratory assistants in these fields. Departments of clinical physiology in university hospitals form a bridge between basic physiology and many clinical specialties. Independent departments of clinical physiology developed early in Sweden due to the work of Professor Torgny Sjöstrand at the Karolinska Hospital in Stockholm, and have been models of research, teaching and hospital organization which have been followed in several other countries. The International Union of Physiological Sciences (IUPS) has recognized clinical physiology as a separate branch of physiology by approving a Commission of Clinical Physiology which has contributed to the programme of this and, we hope, future congresses, as well as promote the development of clinical physiology internationally.

Arsenic and Raynaud's phenomenon. Vasospastic tendency and excretion of arsenic in smelter workers before and after the summer vacation.

Occupational and environmental exposure to inorganic arsenic is associated with the occurrence of Raynaud's phenomenon and objectively registered abnormal finger systolic blood pressure at local cooling (FSP). A subnormal FSP during cooling indicates a vasospastic tendency. It is not known whether these phenomena are related to recent or historical long-term exposure to arsenic. Twenty-one workers from a Swedish smelter were selected on the basis of exposure to arsenic dust for more than 14 years and a previously (three years earlier) recorded subnormal FSP during local cooling. The workers were examined before and after a 4 to 8 week summer vacation. After this intermission in arsenic exposure the urinary excretion of arsenic decreased to normal values, whereas the vasospastic reaction in the fingers remained. Thus the vasospastic tendency seems to be unrelated to the most recent urinary arsenic levels. FSP levels on cooling were significantly increased as compared with the measurements made three years earlier. This suggests a gradual improvement in finger blood circulation caused by decreased exposure to arsenic as evaluated over a time period of several years. The data thus indicate that peripheral vascular disturbances caused by arsenic are dependent on long-term arsenic exposures and are independent of short-term fluctuations in arsenic exposure.

A laser Doppler technique for measuring distal blood-pressure: a comparison with conventional strain-gauge technique.

Twenty-five patients with peripheral circulatory disorders were examined by laser Doppler and strain-gauge techniques to compare these methods of measuring distal systolic blood-pressure. The correlation coefficients for simultaneous measurement of toe and ankle systolic blood-pressures were high, 0.98 and 0.99 respectively. The correlation coefficient for successive measurements of toe pressure was lower, 0.83, probably because of a variation in blood-pressure with time. The laser Doppler method seems to be more sensitive than the strain-gauge method in the low-pressure range. The laser Doppler probe is easy to attach to most skin surfaces and the laser Doppler technique may be, therefore, an alternative and a complement to the strain-gauge method when the strain-gauge is difficult to use on damaged or ulcerous toes and feet.

Relationships between coronary artery obstruction, asynergy, presence of collaterals and the ejection fraction of the left ventricle in patients with coronary heart disease.

Cardioangiographic scores of coronary artery obstructions and corresponding myocardial involvement (MCOS), presence of collaterals (CollS), and asynergy of the left ventricular wall (LVMS) as well as the left ventricular ejection fraction (EF) were examined in 67 patients with coronary heart disease. A covariation was found between LVMS, EF, ECG changes, and a history indicating a previous myocardial infarction (MI). In a multiple regression analysis the EF covariated with LVMS but not with MCOS and CollS. LVMS indicated a previous MI with at least the same sensitivity and specificity as EF. MCOS and CollS give additional information. Collaterals as well as a high MCOS in relation to the LVMS indicate obstruction of coronary arteries which subserve 'non-fibrotic' myocardium. A patient with a high MCOS and CollS and a low LVMS should be expected to gain most functional improvement from coronary bypass surgery. The scores MCOS, CollS and LVMS are comparatively easy to determine and give a more diversified picture of the state of the myocardium than the EF alone.

Cold hands after exposure to arsenic or vibrating tools: effects of ketanserin on finger blood pressure and skin temperature.

The effect of ketanserin, a serotonin 5-HT2 receptor inhibitor, on the cold-provoked vasospasm in arsenic workers was examined by measuring the finger systolic pressure (FSP). After injection of 10 mg ketanserin the skin temperature and the FSP of the cooled finger increased significantly. Prolonged oral treatment with ketanserin, 2 X 40 mg per day, did not significantly influence the skin temperature or FSP during local cooling in arsenic workers or patients with primary or vibration-induced Raynaud's phenomenon. The effect of ketanserin intravenously indicates that serotonin is involved in the mechanism behind vasospasm of arsenic workers in the same way as it is known to be in patients with primary and vibration-induced Raynaud's phenomenon.

Vasospastic tendency and Raynaud's phenomenon in smelter workers exposed to arsenic.

The long-term drinking of water with a high content of inorganic arsenic can lead to Raynaud's phenomenon, acrocyanosis, and gangrene of the lower legs ("black foot disease"). We have measured the systolic blood pressure in the finger after local cooling in 47 workers from a copper smelter who were habitually exposed to moderate amounts of arsenic dust. The controls were 48 workers not exposed to arsenic. The concentration of inorganic arsenic including its metabolites in urine was determined. We found a difference between As-exposed workers and the controls in the finger systolic pressure at skin temperatures of 10 degrees C and/or 15 degrees C expressed as a percentage of the pressure at 30 degrees C (FSP%), P less than 0.01; and the prevalence of Raynaud's phenomenon, P less than 0.05. A low FSP% was taken to indicate vasospastic tendency. There was a covariation between the duration of exposure to arsenic and the decrease in finger systolic pressure between the measurements at 30 and 10 degrees C (P less than 0.05). The uptake of arsenic at the time of the study probably did not exceed 300 micrograms/day. This was confirmed by estimation of the urinary excretion. The average total arsenic uptake was estimated to be about 4 g over 23 years, which is less than the total uptake of 20 g of arsenic by subjects who developed black foot disease. Increased vasospastic reactivity in the fingers and Raynaud's phenomenon in smelter workers seems to be due to functional alterations in the vessels caused by inhalation of arsenic.

Left ventricular asynergy score as an indicator of previous myocardial infarction.

Sixty-eight patients with coronary heart disease (CHD) i.e. a history of angina of effort and/or previous 'possible infarction' were examined inter alia with ECG and cinecardioangiography. A system of scoring was designed which allowed a semiquantitative estimate of the left ventricular asynergy from cinecardioangiography--the left ventricular motion score (LVMS). The LVMS was associated with the presence of a previous myocardial infarction (MI), as indicated by the history and ECG findings. The ECG changes specific for a previous MI were associated with high LVMS values and unspecific or absent ECG changes with low LVMS values. Decision thresholds for ECG changes and asynergy in diagnosing a previous MI were evaluated by means of a ROC analysis. The accuracy of ECG in detecting a previous MI was slightly higher when asynergy indicated a 'true MI' than when autopsy result did so in a comparable group. Therefore the accuracy of asynergy (LVMS greater than or equal to 1) in detecting a previous MI or myocardial fibrosis in patients with CHD should be at least comparable with that of autopsy (scar greater than 1 cm).