Are heart rate monitors valuable tools for diagnosing arrhythmias in endurance athletes?

Millions of physically active individuals worldwide use heart rate monitors (HRMs) to control their exercise intensity. In many cases, the HRM indicates an unusually high heart rate (HR) or even arrhythmias during training. Unfortunately, studies assessing the reliability of these devices to help control HR disturbances during exercise do not exist. We examined 142 regularly training endurance runners and cyclists, aged 18-51 years, with unexplained HR abnormalities indicated by various HRMs to assess the utility of HRMs in diagnosing exertion-induced arrhythmias. Each athlete simultaneously wore a Holter electrocardiogram (ECG) recorder and an HRM during typical endurance training in which they had previously detected "arrhythmias" to verify the diagnosis. Average HRs during exercise were precisely recorded by all types of HRMs. No signs of arrhythmia were detected during exercise in approximately 39% of athletes, and concordant HRs were recorded by the HRMs and Holter ECG. HRMs indicated surprisingly high short-term HRs in 45% of athletes that were not detected by the Holter ECG and were artifacts. In 15% of athletes, single ventricular/supraventricular beats were detected by the Holter ECG but not by the HRM. We detected a serious tachyarrhythmia in the HRM and Holter ECG data with concomitant clinical symptoms in only one athlete, who was forced to cease exercising. We conclude that the HRM is not a suitable tool for monitoring heart arrhythmias in athletes and propose an algorithm to exclude the suspicion of exercise-induced arrhythmia detected by HRMs in asymptomatic, physically active individuals.

Hoveyda-Grubbs catalyst analogues bearing the derivatives of N-phenylpyrrol in the carbene ligand - structure, stability, activity and unique ruthenium-phenyl interactions.

We have synthesized a series of N-phenylpyrrole and N-phenylindole carbenes and used them as ruthenium-ligating moieties in the synthesis of Hoveyda-Grubbs catalyst derivatives. We show that most of these complexes are difficult to synthesize and unstable apart from the N-phenylpyrrole-2,6-diisopropylphenyl ruthenium complex and its perbrominated derivative. These two systems are almost completely inactive in ring-closing metathesis at room temperature and become active only at 80 °C. DFT, SAPT0 and DLPNO-CCSD(T) calculations suggest that the rarely occurring phenyl-ruthenium interactions are responsible for the very slow initiation of these precatalysts at low temperatures.

[Changes of alpha-amylase activity in serum and urine of patients with various histological types of lung cancer]. / Zmiany aktywnosci alfa-amylazy w surowicy i moczu u chorych z róznymi typami histologicznymi raka pluca.

Serum and urinary activity of alpha-amylase was assessed in different types and clinical stages of lung cancer. Significantly increased activity was seen in adenocarcinoma and in stage III of the disease. Following surgical removal of the tumor alpha-amylase decreased on the 7th day by 19% and on the 21st day by 26.8%. The activity of urinary alpha-amylase also decreased. The authors have determined the thermostable fraction of the alpha-amylase which may imply the source of the enzyme in the serum.

[Activity of granulocytic alpha-amylase in patients with pneumonia]. / Aktywnosc alpha-amylazy granulocytarnej u chorych na zapalenie pluc.

In 35 patients with pneumonia we have tested alpha-amylase activity in isolated blood granulocytes as well in sera as in urines. The received data were compared to the results obtained in 35 healthy control group. Studied has been determined in 1 and 7 day hospitalization. Mean activity of the enzyme in granulocytes of patients was 38% higher than that in the control group. In 34% of subjects studied an increase of the enzyme activity in the serum. The results of above studies indicate that the increased activity of the enzyme in the serum of patients with pneumonia is due to the enzyme activity increase in granulocytes.

The activity of granulocyte alpha-amylase in acute appendicitis.

The activity of alpha-amylase was measured in isolated granulocytes, serum and urine of 35 patients with acute appendicitis. The measurements were performed before operation and on the 7th day after operation. Slightly increased activity of alpha-amylase was found in the serum and urine of 15 patients. On the 7th day after operation the activity of this enzyme reached normal value. The activity of granulocyte alpha-amylase was elevated in 22 patients. In 2 of them the increased activity still maintained on the 7th day after operation. Positive correlation between the serum and granulocyte alpha-amylase activities was found. These observations allow to conclude that granulocytes are the source of increased alpha-amylase activity in the serum of patients with acute appendicitis.