Prevalence of small-scale jets from the networks of the solar transition region and chromosphere

As the interface between the Sun's photosphere and corona, the chromosphere and transition region play a key role in the formation and acceleration of the solar wind. Observations from the Interface Region Imaging Spectrograph reveal the prevalence of intermittent small-scale jets with speeds of 80 to 250 kilometers per second from the narrow bright network lanes of this interface region. These jets have lifetimes of 20 to 80 seconds and widths of ≤300 kilometers. They originate from small-scale bright regions, often preceded by footpoint brightenings and accompanied by transverse waves with amplitudes of ~20 kilometers per second. Many jets reach temperatures of at least ~10(5) kelvin and constitute an important element of the transition region structures. They are likely an intermittent but persistent source of mass and energy for the solar wind.

Evidence of nonthermal particles in coronal loops heated impulsively by nanoflares

The physical processes causing energy exchange between the Sun's hot corona and its cool lower atmosphere remain poorly understood. The chromosphere and transition region (TR) form an interface region between the surface and the corona that is highly sensitive to the coronal heating mechanism. High-resolution observations with the Interface Region Imaging Spectrograph (IRIS) reveal rapid variability (~20 to 60 seconds) of intensity and velocity on small spatial scales (≲500 kilometers) at the footpoints of hot and dynamic coronal loops. The observations are consistent with numerical simulations of heating by beams of nonthermal electrons, which are generated in small impulsive (≲30 seconds) heating events called "coronal nanoflares." The accelerated electrons deposit a sizable fraction of their energy (≲10(25) erg) in the chromosphere and TR. Our analysis provides tight constraints on the properties of such electron beams and new diagnostics for their presence in the nonflaring corona.

The unresolved fine structure resolved: IRIS observations of the solar transition region

The heating of the outer solar atmospheric layers, i.e., the transition region and corona, to high temperatures is a long-standing problem in solar (and stellar) physics. Solutions have been hampered by an incomplete understanding of the magnetically controlled structure of these regions. The high spatial and temporal resolution observations with the Interface Region Imaging Spectrograph (IRIS) at the solar limb reveal a plethora of short, low-lying loops or loop segments at transition-region temperatures that vary rapidly, on the time scales of minutes. We argue that the existence of these loops solves a long-standing observational mystery. At the same time, based on comparison with numerical models, this detection sheds light on a critical piece of the coronal heating puzzle.

On the prevalence of small-scale twist in the solar chromosphere and transition region

The solar chromosphere and transition region (TR) form an interface between the Sun's surface and its hot outer atmosphere. There, most of the nonthermal energy that powers the solar atmosphere is transformed into heat, although the detailed mechanism remains elusive. High-resolution (0.33-arc second) observations with NASA's Interface Region Imaging Spectrograph (IRIS) reveal a chromosphere and TR that are replete with twist or torsional motions on sub-arc second scales, occurring in active regions, quiet Sun regions, and coronal holes alike. We coordinated observations with the Swedish 1-meter Solar Telescope (SST) to quantify these twisting motions and their association with rapid heating to at least TR temperatures. This view of the interface region provides insight into what heats the low solar atmosphere.

Hot explosions in the cool atmosphere of the Sun

The solar atmosphere was traditionally represented with a simple one-dimensional model. Over the past few decades, this paradigm shifted for the chromosphere and corona that constitute the outer atmosphere, which is now considered a dynamic structured envelope. Recent observations by the Interface Region Imaging Spectrograph (IRIS) reveal that it is difficult to determine what is up and down, even in the cool 6000-kelvin photosphere just above the solar surface: This region hosts pockets of hot plasma transiently heated to almost 100,000 kelvin. The energy to heat and accelerate the plasma requires a considerable fraction of the energy from flares, the largest solar disruptions. These IRIS observations not only confirm that the photosphere is more complex than conventionally thought, but also provide insight into the energy conversion in the process of magnetic reconnection.

Clopidogrel increases expression of chemokines in peripheral blood mononuclear cells in patients with coronary artery disease: results of a double-blind placebo-controlled study

BACKGROUND

Chemokines and platelet activation are both important in atherogenesis. Platelet inhibitors are widely used in coronary artery disease (CAD), and we hypothesized that the platelet inhibitor clopidogrel could modify chemokines in CAD patients.

OBJECTIVES

We sought to investigate the effect of clopidogrel on the expression of chemokines and chemokine receptors in peripheral blood mononuclear cells (PBMC) in CAD patients.

PATIENTS/METHODS

Thirty-seven patients with stable angina were randomized to clopidogrel (n = 18) or placebo (n = 19). PBMC, blood platelets and plasma were collected at baseline and after 7-10 days in the patients, and in 10 healthy controls. mRNA levels of chemokines and chemokine receptors in PBMC were analyzed by ribonuclease protection assays and real-time reverse transcriptase polymerase chain reaction. Platelet activation was studied by flow cytometry.

RESULTS

(i) At baseline, the gene expression of the regulated on activation normally T-cell expressed and secreted (RANTES) chemokines and macrophage inflammatory peptide (MIP)-1beta in PBMC, the expression of CD62P and CD63 on platelets and the levels of platelet-derived microparticles (PMP) were elevated in angina patients comparing healthy controls; (ii) markers of platelet activation were either reduced (CD63) or unchanged (CD62P, PMP, beta-thromboglobulin) during clopidogrel therapy; (iii) in contrast, clopidogrel significantly up-regulated the gene expression of RANTES and MIP-1beta in PBMC, while no changes were found in the placebo group; (iv) a stable adenosine 5'-diphosphate metabolite attenuated the release of MIP-1beta, but not of RANTES, from activated PBMC in vitro.

CONCLUSIONS

Even if we do not argue against a beneficial role for clopidogrel in CAD, our findings may suggest potential inflammatory effects of clopidogrel in CAD.

[Prevention of cardiovascular disease in type 2 diabetes]

BACKGROUND

Patients with type 2 diabetes have a high risk of morbidity and premature mortality from cardiovascular disease. Epidemiological studies show that many of the risk factors are the same as in non-diabetic subjects. At present there are sufficient data in the literature to recommend prophylactic measures to be initiated in diabetic patients.

MATERIAL AND METHODS

We review major studies relevant for prophylactic measures against cardiovascular disease in patients with type 2 diabetes, and suggest Norwegian recommendations.

RESULTS

All patients should be advised to adhere to a healthy life style including an appropriate diet, physical exercise and no smoking. Treatment of hyperglycaemia is primarily indicated in order to improve quality of life and reduce the risk of microvascular complications, as it still remains to be proven if glucose lowering therapy may protect against macrovascular disease. Pharmacological prophylactic therapy with acetylsalicylic acid, anti-hypertensive agents and lipid lowering drugs are indicated in high-risk patients.

IMPLICATIONS

Several pharmacological and non-pharmacological interventions may protect type 2 diabetic patients from premature cardiovascular morbidity and mortality. Anti-hypertensive treatment may protect diabetic patients both from microvascular and macrovascular disease and premature death.

[Current use of beta-blockers in coronary artery disease]

This article presents the results of a retrospective analysis of the use of beta-blockers and current dosing of these agents in patients with coronary artery disease. While 70 to 78% of patients admitted to Norwegian university hospitals during 1990-1997 for angiographic evaluation of chest pain used beta-blockers, only 43-60% of patients with stable coronary artery disease enrolled in the 4S study in Norway received such treatment. High risk groups such as diabetics and patients with peripheral artery disease were less likely to receive beta-blockers during the early period, but were not treated differentially compared to low risk patients during recent years. Only 15% of patients with congestive heart failure received oral beta-blockers, and only 10.5% intravenous beta-blockade during acute myocardial infarction. The dosing of the most common beta-blockers were low, approximately 50% of doses shown to improve survival after acute myocardial infarction.

[The heart bridge. A follow-up study of cardiac patients from the health region 1 operated abroad during the period 1985-87]

During the years 1985 to 1987 a total number of 388 patients from the Norwegian health region 1 were transferred from Ullevål Hospital to heart centres abroad for heart operation because of the low operating capacity in our own hospital. The operative mortality in pure coronary bypass operations was 6.0%. Six out of 34 patients (17.6%) died postoperatively following valvular replacements. A questionnaire was sent to all survivors in November, 1989 and July, 1996. The clinical condition was judged to be very good or good by 95% and 83% of the patients, respectively. A self-evaluation of quality of life on a visual analog scale indicated a significant improvement after the operation.

Comparative effects of long-acting and conventional propranolol on stress-induced angina pectoris and on frequency of ventricular premature beats

Ten male patients with chronic stable angina pectoris completed a randomized, double-blind cross-over study, with matched placebo run-in period (P), to compare the effects of a long-acting preparation of propranolol (LA, 160 mg once a day) with that of conventional propranolol (CP, 40 mg four times a day) each given for 14 days. Response was assessed by symptom-limited bicycle ergometry, degree of ST segment depression, daily anginal attack rate and glyceryl trinitrin consumption (GTN). Heart rate and ventricular extra-systolic frequency (VES) were recorded by 24 h Holter monitor. Bicycle ergometry was performed and a trough blood sample taken for propranolol estimation on day 14 prior to the morning dose. Both formulations increased total work capacity (P 3412, LA 4095, CP 3697 kpm/min), reduced rate-pressure product (P 21896, LA 16011, CP 15609 mm Hg beats/min), and degree of ST segment depression (P 4.53, LA 2.48, CP 2.43), but without differences between the formulations. Daily anginal attack rate was reduced from 30 (placebo) to 7.5 (CP) and 14.5 (LA) (P less than 0.05 between treatment groups). There was a reduction in daily GTN consumption by both treatments. The heart rate and total number of VESs during 24 h was similar in the two treatment groups and was reduced in comparison with placebo. Both formulations were well tolerated. Long-acting propranolol is an effective and well-tolerated alternative to conventional propranolol in the treatment of chronic stable and stress-induced angina, and in reducing VES frequency.

Beta blockade after myocardial infarction: the Norwegian propranolol study in high-risk patients

A randomized, double-blind, placebo-controlled trial of propranolol was carried out in 560 high-risk survivors of myocardial infarction enrolled at 12 Norwegian hospitals. The main purpose of the study was to determine the effect of propranolol, 160 mg/day, on the incidence of sudden cardiac death over 12 months. The patients were randomized 4-6 days after the acute event. A statistically significant reduction in sudden cardiac deaths of 52% was noted (11 deaths in the propranolol group and 23 in the placebo group). Four placebo patients and one propranolol patient were successfully resuscitated from ventricular fibrillation. In addition, less severe ventricular arrhythmias were significantly more common among the placebo-treated patients. Twenty-five patients in the treatment group and 37 in the control group died (p = 0.11). Severe adverse effects of the drug were uncommon in this high-risk population. The findings support the results of the Beta-Blocker Heart Attack Trial and other long-term beta-blocker trials in survivors of myocardial infarction.

One year's treatment with propranolol after myocardial infarction: preliminary report of Norwegian multicentre trial

A prospective, randomised, double-blind study was performed to compare the effects of propranolol and placebo on sudden cardiac death in a high-risk group of patients who survived acute myocardial infarction. Altogether 4929 patients with definite acute myocardial infarction were screened for inclusion: 574 (11.6%) died before randomisation, and 3795 (77%) were excluded. Five hundred and sixty patients aged 35 to 70 years were stratified into two risk groups and randomly assigned treatment with propranolol 40 mg four times a day or placebo. Treatment started four to six days after the infarction. By one year there had been 11 sudden deaths in the propranolol group and 23 in the placebo group (p less than 0.038, two-tailed test analysed according to the "intention-to-treat" principle). Altogether there were 25 deaths in the propranolol group and 37 in the placebo group (P less than 0.12), with 16 and 21 non-fatal reinfarctions respectively. A quarter of the patients were withdrawn from each group. Withdrawal because of heart failure during the first two weeks of treatment was significantly more common among propranolol-treated patients than among the controls, but thereafter the withdrawal rate was the same. The significant reduction in sudden death was comparable with that after alprenolol, practolol, and timolol, which suggests that the mechanism of prevention is beta-blockade rather than any other pharmacological property of the individual drugs.

Effect of heparin on serum binding of propranolol in the acute phase of myocardial infarction

1 Binding of propranolol in vitro was determined in sera from 38 non-fasting patients 4-6 days after an acute myocardial infarction. The binding of propranolol was significantly lower in 12 patients receiving a subcutaneous heparin injection than in 26 patients receiving warfarin.

2 The binding of propranolol in sera from 9 geriatric patients without any acute diseases and 10 young, healthy subjects was similar to that of patients with acute myocardial infarction receiving heparin.

3 Mean serum concentration of α₁-acid glycoprotein was similar in the four different groups of individuals.

4 For all subjects, the binding of propranolol was positively correlated to serum concentrations of α₁-acid glycoprotein.

5 In the patients with myocardial infarction the binding was negatively correlated to serum concentrations of non-esterified fatty acids. Mean serum concentrations of non-esterified fatty acids was significantly higher in the patients receiving heparin than those receiving warfarin.

6 Addition of heparin and palmitic acid to serum in vitro did not affect the binding of propranolol.

7 The effect of heparin on binding variations was observed more closely in three non-fasting patients with myocardial infarction. Serum binding of propranolol and concentrations of chylomicrons and pre-β-lipoproteins were significantly reduced after a subcutaneous heparin injection of 5,000 iu, while serum concentrations of non-esterified fatty acids increased threefold. Concentrations of α₁-acid glycoprotein and albumin were unchanged. Changes in binding of propranolol was closely correlated to concomitant changes in the triglyceride-rich lipoproteins.

8 These observations indicate that propranolol is bound to both triglyceride-rich lipoproteins and α₁-acid glycoprotein in serum. Even smaller doses of heparin activate lipoprotein lipase and decrease binding of propranolol to lipoproteins in non-fasting subjects.

Acute, massive poisoning with digitoxin: report of seven cases and discussion of treatment

Severe digitoxin poisoning in seven patients is reported. Doses taken varied from 2 to 20 mg, and maximal plasma concentrations of digitoxin from 50 to 237 nmol/L. One patient died from ventricular fibrillation, and the course in another was considerably protracted due to severe complications. The course in all patients was more dependent on underlying heart disease than on the plasma digitoxin concentration. Based on our own experiences and survey of the literature the following treatment is proposed: Gastric aspiration and lavage followed by instillation of activated charcoal should even be performed many hours after drug intake. In order to interrupt the enterohepatic circulation of digitoxin, repeated doses of charcoal should be given. Charcoal is preferable to cholestyramine because of its better tolerability. Ventricular arrhythmias should not be treated unless they are serious, because most antiarrhythmic drugs may further impede the AV-conduction. Phenytoin is the drug of choice, because the AV-conduction is less affected or even improved, and because the metabolism of digitoxin is accelerated. Conduction disturbances with bradycardia are frequently seen and may occur suddenly. Prophylactic introduction of a transvenous pacing catheter is therefore recommended as a routine procedure.

Ergotism in a patient with a portosystemic shunt

A case of ergotism is described in a patient with Banti's syndrome in whom a porto-systemic shunt had been made three times. She was admitted to hospital with severe ischaemia of the extremities after having taken a single oral dose of 1 mg ergotamine tartrate. Her condition improved rapidly after 2 to 3 days and the circulation was normal after one week. The possible mechanism of ergotism in this patient is discussed. Although the plasma concentration of ergotamine was not measured, the likeliest explanation was that the serious side effects were related to the altered pharmacokinetics and loss of first-pass metabolism of the drug due to the venous bypass of the liver.

Cardiac arrhythmias in patients with serious pulmonary diseases

During a 5-year period, 1969-1973, 451 patients with acute severe pulmonary diseases were admitted to the three medical intensive care units (MICU) at Ullevaal Hospital. In 39% of the patients a major cardiac arrhythmia was recorded in the units during a mean observation time of 24 h. The subsequent mortality in the hospital was 31% in patients with arrhythmias in the MICU, and 8% in patients without arrhythmias. The association between arrhythmias and mortality was significant (P less than 0.004) in patients with a diagnosis of pneumonia. There was also an association (P less than 0.04) between arrhythmias and the severity of lung disease. Continuous electrocardiographic monitoring of patients with severe pneumonia or acute exacerbations of obstructive lung disease is recommended.

Studies on digitalis. XIII. A prospective study of 649 patients on maintenance treatment with digitoxin

In a prospective study of digitalis intoxication in 649 patients on maintenance treatment with digitoxin a low incidence of digitalis toxicity was found, namely, 5.8 per cent. This is mainly due to a more careful use to digitalis glycosides. It is especially important to reduce the dose of digitoxin in the liver and partly excreted metabolized in the liver and partly excreted through the kidneys as metabolities. Serum half-time of digitoxin is shortened in patients with impaired renal function. Patients with reduced renal function may be treated with digitoxin in the same doses as individuals with normal renal function. This is in contrast to patients treated with digoxin. Digitoxin should therefore be the cardiac glycoside of choice in treatment of patients with renal failure. Digitoxin is further rapidly eliminated in patients with reduced liver function in spite of its extensive hepatic metabolism. In this study extracardia symptoms were found equally often as cardiac signs of toxicity. Patients intoxicated usually had several symptoms and signs of toxicity at the same time. The specificity of commonly used symptoms and signs a digitalis intoxication is very low. In this study atrial tachycardia with block, which has been considered to be an important cardiotoxic arrhythmia, very seldom was found in digitalis intoxication. There is an overlap in digitalis serum concentration between toxic and nontoxic patients. The diagnosis of toxicity was made on clinical grounds. Most of the intoxicated patients had high serum concentrations, but some had concentrations in the normal or low range. Apart from being a guide to the diagnosis of digitalis intoxication, serum digitalis levels may further be a guide to underdigitalization of cardiac patients, especially patients in sinus rhythm.

Maintenance therapy with a new retard tablet preparation of procainamide

The procainamide plasma concentration was followed during maintenance therapy with a new procainamide retard tablet preparation in 23 hospitalized patients suffering from acute or chronic coronary heart disease with complicating ventricular arrhythmias. After initial individually adjusted treatment with Pronestyl every third hour, either orally or intramuscularly, for at least eight dose intervals, the retard tablets were given at 6 hour intervals for 2 to 12 days, or more. In 19 patients with no major fluctuations in their circulatory or renal state, adequate and relatively stable plasma procainamide concentration was obtained upon a constant dose of the retard preparation. On an average, the difference from minimum to maximum concentration was 55 per cent within the 6 hour dose intervals. In four patients with unstable circulation and/or renal function, procainamide therapy had to be disrupted in two because of severe side effects and toxic concentrations, and the dose was adjusted in the remaining two. It is concluded that the formulation of procainamide tablet preparations has simplified procainamide therapy within and outside hospital and improved our possibilities to perform short-and long-term studies on the risk/ benefit ratio of procainamide treatment in patients with severe ventricular arrhythmias.

Comparison of the acetylation of procainamide and sulfadimidine in man

The acetylation of procainamide and sulfadimidine has been measured simultaneously in plasma and urine in 20 healthy human volunteers by a specific G.L.C. method, after single and multiple oral dral doses of procainamide retard tablets. A distinct bimodality (9 rapid and 11 slow acetylators) was apparent from the concentrations of procainamide and N-acetylprocainamide both in urine and plasma, which was in complete agreement with data about sulfadimidine acetylation. The influence of acetylator phenotype on the relative concentrations of procainamide and N-acetylprocainamide in plasma as cn 5 additional healthy subjects after a single oral dose of procainamide. The present results show that acetylator phenotype can now be determined using procainamide as the test substance, and for this purpose multiple doses offer hardly any advantage over a single dose of the drug. However, because the separation between rapid and slow acetylators is less pronounced for procainamide than for sulfadimidine, precise criteria must be established for the conditions of the test, and the influence of diseases, such as renal insufficiency, should be taken into consideration.

Induced hypertension in the treatment of severe ischemia of the foot

The present paper reports the results of angiotensin infusion in 11 patients with severe atherosclerosis of the lower limbs adding a brief discussion of indications with inherent dangers and contraindications.

The study confirms the results of Dahn et al. 4,5 that pharmacologically induced hypertension may increase distal perfusion pressure and flow and relieve resting pains. It is our opinion, however, that only a very limited number of patients presenting with severe foot ischemia and resting pains can profit from this treatment because of frequent contraindications such as coexistent hypertension and coronary heart disease.