Effects of age and training status on heart rate recovery after peak exercise

Previous studies have shown that the kinetics of heart rate (HR) recovery are delayed in older individuals after exercise. This study was designed to determine whether this observation held when the variables of physical fitness and work intensity were controlled. Twenty male subjects were categorized into four groups (n = 5) according to age and fitness level (peak O2 consumption ml. kg-1.min-1): young trained (YT) 24 +/- 2 yr, 63 +/- 3 ml.kg-1. min-1; old trained (OT) 51 +/- 2 yr, 57 +/- 3 ml.kg-1.min-1; young untrained (YU) 25 +/- 3 yr, 44 +/- 2 ml.kg-1.min-1; old untrained (OU) 57 +/- 4 yr, 36 +/- 4 ml.kg-1.min-1. Bicycle ergometry exercise was performed in incremental stages to a maximally tolerated level of exertion, and HR was monitored continuously postexercise. Regression analysis of the fast (15-120 s) and initial slow (120-240 s) phases of recovery showed no effect of age on HR recovery when comparing YT vs. OT and YU vs. OU. Trained subjects, irrespective of age, demonstrated a significantly faster HR recovery than untrained subjects which was particularly marked during fast-phase recovery (P less than 0.005). These results indicate that the slower HR recovery previously reported in older subjects may be due to a failure to control for variables that influence recovery HR.

Overview of venous thrombogenesis

In the pathogenesis of venous thrombosis, stasis is essentially a permissive factor, allowing the normal defense mechanisms of the body to be circumvented. Although a platelet monolayer is an insufficient stimulus for fibrin formation, even in the presence of stasis, trace amounts of an activated clotting factor are highly thrombogenic in an area of retarded blood flow. The available clinical and experimental data suggest that, if thrombin generation is reduced, the great majority of venous thrombi are prevented.

Experimental studies on the relative efficacy of dermatan sulphate and heparin as antithrombotic agents

In this study, the anticoagulant and antithrombotic properties of unfractionated heparin (UFH) and dermatan sulphate (DS) were compared. The ability of UFH and DS to impair thrombin generation in vitro and in ex vivo plasma samples was also studied. DS has minimal anticoagulant activity by conventional assays but impairs thrombin generation both in vitro and in ex vivo plasma samples. However, thrombin generation could not be suppressed below about 35% of control values at all doses of DS studied. While this was sufficient to impair experimental venous thrombosis during 10 minutes' stasis, DS was ineffective in preventing thrombosis following 20 minutes' stasis in doses up to 1.25 mg/kg. In contrast, 1 microgram/ml of UFH completely suppressed thrombin generation in vitro, and 150 micrograms/kg prevented thrombogenesis over a period of 20 minutes' stasis. Neither drug prolonged the bleeding time (BT) at effective antithrombotic doses, but 2.5 mg/kg UFH significantly increased the BT, whereas DS did not. While DS has antithrombotic activity, it is less effective than UFH in inhibiting thrombin generation, and as an antithrombotic agent.

Algodystrophy: a common unrecognized cause of chronic knee pain

Thirty-three patients with undiagnosed chronic knee pain had features of autonomic disturbance. Thermography is a useful imaging technique for demonstrating this abnormality. The patients lacked the thermographic symmetry observed in 16 normal controls but this returned with resolution of the pain. Recognized radiological and scintigraphic features of algodystrophy were found. The long duration of symptoms, high proportion of young females and the severity of the associated disability were notable. It is suggested that algodystrophy is a more frequent cause of chronic knee pain than previously recognized. Autonomic abnormalities may be less intense in disease at this site, particularly in young females and may be overlooked. This characteristic of algodystrophy of the knee may contribute to chronicity and subsequent disability.

Anticoagulant activities of pentosan polysulphate (Hémoclar) due to release of hepatic triglyceride lipase (HTGL)

Subcutaneous injections of 50 mg pentosan polysulphate (Hémoclar) were given to normal volunteers and the effects on anti-Factor Xa activity, thrombin generation and lipase release measured. Concentrations of pentosan polysulphate were measured by a competitive binding assay and the mean peak level found to be 1.6 micrograms/ml. Anti-Xa clotting activity rose to 0.034 iu/ml and thrombin generation induced by lipid peroxides was inhibited by approximately 50%. Neither of these effects could be accounted for by the direct action of pentosan polysulphate at the concentrations measured. Pentosan polysulphate was very effective in releasing lipase, approximately 70-80% of the total enzyme activity being due to hepatic triglyceride lipase (HTGL). In vitro addition of purified HTGL to plasma markedly enhanced anti-Xa clotting activity, and caused a 70% inhibition of lipid peroxide induced thrombin generation. Anti-Xa activity of post-injection plasma was increased rather than neutralised by addition of polybrene, and this effect could be mimicked by addition of polybrene to plasma containing pentosan polysulphate and purified HTGL. It is concluded that, when given in low doses subcutaneously, pentosan polysulphate acts as an indirect anticoagulant, its major effects being due to release of HTGL.

Combined effects of exercise and restriction of energy intake on moderately obese women

The current study was designed to assess the contribution of dietary-induced weight reduction on improvements in functional capacity in moderate obesity. Twelve females (means age = 29 yr, means fat percentage = 37%) served as subjects for the study. Subjects trained on a cycle ergometer 30 min.day-1, six day.wk-1 for three or six weeks at 75 to 85 per cent of maximum heart rate (HR max). Improvements in maximal oxygen uptake (delta VO2 max I.min-1) and functional capacity (delta VO2 max ml.kg-1 min-1) were compared in an attempt to separate out training and dietary effects respectively. Measurements were also taken on both the cycle ergometer and treadmill to test for any specificity of training effects. Changes in body composition were assessed by densitometry. Following three weeks of training, there was an average increase in VO2 max ml.kg-1 min-1 on the cycle ergometer and the treadmill of 14 and 19 per cent respectively. By six weeks, this had increased to 18 and 26 per cent respectively. The contribution of weight reduction to the improvements in functional capacity was calculated to range from 20 to 33 per cent. Thus, both energy restriction and exercise training appear to be effective means of improving functional capacity in moderately obese women.

Effects of beta 1- vs. beta 1- beta 2-blockade on training adaptations in rat skeletal muscle

The effect of selective vs. nonselective beta-blockade on fast-twitch [extensor digitorum longus (EDL)] and slow-twitch [soleus (SOL)] muscle enzyme activities following endurance training were characterized. Citrate synthase (CS), lactate dehydrogenase (LDH), and beta-hydroxyacyl-CoA dehydrogenase (HAD) activities were compared in SOL and EDL muscles of trained (T), metoprolol-trained (MT), propranolol-trained (PT), and sedentary (C) rats. Following 8 wk of treadmill running (1 h/day, 5 days/wk at approximately 30 m/min), LDH activity was depressed approximately 20% (P less than 0.05) in both SOL and EDL in only the PT rats, indicating inhibition of beta 2-mediated anaerobic glycolysis. EDL CS activity was similarly elevated in all three trained groups compared with sedentary controls. In SOL muscle, however, a drug attenuation effect was observed so that CS activity was increased only in the T (P less than 0.01) and MT (P less than 0.05) groups. HAD enzyme activity was increased somewhat (P less than 0.10) in SOL muscle in only the T group, but more so (P less than 0.05) in EDL in all three trained groups. The above findings suggest a training-induced selectivity effect not only with respect to beta 1-vs. beta 1-beta 2-blockers, but also with respect to muscle fiber type.

Low molecular weight heparin: a better drug?

Preliminary clinical trials suggest that at least some low molecular weight (LMW) heparins are as effective as heparin in preventing post-operative deep vein thrombosis, and need only be injected once a day. However, a firm basis does not exist for assigning potency estimates to different LMW heparins. Caution is therefore necessary in determining appropriate dosages for various clinical indications. Until the problems of standardization and dosage are resolved, LMW heparins are unlikely to achieve their potential usefulness, or prove safer than standard heparin.

Thermographic diagnosis in athletes with patellofemoral arthralgia

Pain in front of the knee is common in athletes and is often called patellofemoral arthralgia, but it is difficult to prove that the pain arises in that joint. Thermograms of 30 athletes clinically considered to have patellofemoral arthralgia were compared with those of a similar number of unaffected athletes matched for age and sex. A comparison was also made with thermograms of two older groups of 30 patients with knee involvement from either rheumatoid arthritis or osteoarthritis. Twenty-eight of the athletes with patellofemoral arthralgia had a diagnostic pattern on thermography. The anterior knee view showed a rise in temperature on the medial side of the patella and the medialis knee view showed that this temperature rise radiated from the patellar insertion of the vastus medialis into the muscle itself. The possible aetiological role of quadriceps muscle imbalance in athletes with patellofemoral arthralgia is discussed in relation to these findings.

Experimental studies on venous thrombosis: effect of coagulants, procoagulants and vessel contusion

We have examined the relative contribution of stasis, activated coagulants, procoagulants and vessel wall damage in the pathogenesis of experimental venous thrombosis. Using a Wessler stasis model in rabbits, we found an inverse correlation between duration of stasis and the amount of Contact Factor and Factor Xa required to produce a stasis thrombus. However, the slope of the dose-response curve for producing thrombi was different with these two coagulants. The infusion of Factor IX complex was also thrombogenic in this model despite prolonged circulation prior to stasis, implying that high levels of multiple procoagulants may be thrombogenic. In contrast, Factor VIII concentrates or a purified Factor IX preparation did not give thrombi under these conditions. When the vessel wall was crushed mechanically, followed by restored blood flow and subsequent stasis, there was essentially no formation of thrombi over the time course of the experiments. Scanning electron microscopy demonstrated that although the endothelium was swollen and damaged, there was usually no exposure of sub-endothelium and no adherence platelets. Where there was definite disruption of the endothelium, activated platelets could be seen adhering to the vessel wall. However, the blood in the segments remained fluid over a period of 30 min, despite the presence of adherent platelets. Our experiments demonstrated that the combination of vessel wall damage and stasis was relatively ineffective in producing venous thrombosis. In contrast, high levels of zymogens or small amounts of activated clotting factors, combined with local stasis, is a very effective thrombogenic stimulus in the venous system.

Benign fibrous histiocytoma of bone

The clinical, radiologic, and pathological features of eight cases of fibrohistiocytic bone lesions histologically identical to the nonossifying fibroma of childhood are presented. They differed from the childhood lesion in their clinical and radiological features. They occurred in adults, and were frequently associated with pain in the absence of complicating fracture. They were not confined to the metaphysis of long bones. When metaphyseal, the lesions also frequently showed a tendency to involve the epiphysis. Others occurred in the diaphysis of long bones, in the pelvis, and in a rib. Three recurred locally, but none has metastasized. Other fibrohistiocytic and fibroblastic tumours of bone, including malignant fibrous histiocytoma, giant cell tumour, fibrosarcoma, and desmoplastic fibroma can be differentiated on radiological and histological features, and hyperparathyroidism may need to be excluded by biochemical investigations.

Standardization of low molecular weight heparins: a collaborative study

A collaborative study was carried out, in which eight laboratories each assayed eight low molecular weight (LMW) heparins against the International Standard (IS) for heparin. APTT assays and three types of anti-Xa method were used. The results of this study showed that: LMW heparins cannot be validly assayed against the IS by APTT or anti-Xa methods. Potencies of LMW heparins vs. the IS differed considerably between the four types of assay method used and also between different laboratories using the same type of method. Adoption of a single LMW heparin standard would improve validity, improve inter-laboratory variation, and largely abolish the differences between the three types of anti-Xa method. However, since calibration of a LMW heparin standard against the IS would give potencies that differ widely by the different assay methods, a single assay method such as the anti-Xa amidolytic, plasma, would need to be chosen for this calibration.

Effects of acute and chronic exercise on myocardial ultrastructure

Histological and ultrastructural evaluation of the heart reveals that structural alterations may be induced by both acute and chronic exposure to exhaustive exercise. Following an acute bout of exercise to the point of exhaustion, the normal heart does not appear hypoxic as assessed by mitochondrial morphology. However, small shifts in intracellular volume fractions as well as dilatation of transverse tubules and sarcoplasmic reticulum have been observed. The functional significance of these ultrastructural changes is not well understood, but could explain any alterations in contractility observed at this point in time. Following repeated exposure to strenuous dynamic exercise on a daily basis for an extended period of time (endurance training), the effects seem to be principally on the vasculature of the heart, with no alterations in composition of the myocardial cell. This is manifested by an increase in size of the major coronary arteries and a corresponding change in the number of capillaries. The chronic effects of exercise on coronary arterioles are unknown. The results of retrospective studies in humans and laboratory experiments with primates and lower mammals indicate that these training-induced structural alterations may play a protective role with respect to coronary heart disease. Most importantly, this role would appear to be both preventive and rehabilitative in nature.

Disease activity indexes in rheumatoid arthritis; a prospective, comparative study with thermography

There are many difficulties associated with the assessment of disease activity in rheumatoid arthritis. Infrared thermography has been used to quantify joint inflammation. The heat distribution index (HDI) is reproducible, sensitive, quantifiable, and not subject to circadian variation or interobserver error. In this study the HDIs for both elbows, wrists, knees, and ankles were summated and compared with other parameters of disease activity. There were 167 sets of observations in 20 patients with classical, seropositive, rheumatoid arthritis followed up over 12 months. There was a significant correlation (p less than 0.001) for thermography with the Ritchie articular index, Mallya score, grip strength, morning stiffness, erythrocyte sedimentation rate, and pain score. Significant correlations (p less than 0.05) for thermography with these parameters were found in individual patients. The summated HDI is a suitable, objective method for the assessment of response to therapy in patients with rheumatoid arthritis.

A radiographic anthology of vertebral names

There are many conditions of the spine to which various authors have applied descriptive names. This paper, an extensive review of the literature, provides the first complete source for such named vertebrae. Included are 88 names covering all categories of bone disease. A brief description of the radiographic appearance and its pathogenesis is provided for each, along with a consideration of the disease processes which may produce the appearance.

Standardization of prekallikrein activator (PKA): the 1st International Standard for PKA

A international collaborative study was carried out to establish an international standard for prekallikrein activator (PKA). The candidate material, coded 82/530, was assayed against the Office of Biologics (FDA) PKA reference preparation No. 2 (OoB 2) and the 1st British Reference Preparation for PKA. There was good agreement between participant laboratories on the relative PKA activity of the three preparations. Preparation 82/530 has been established by the World Health Organization as the 1st I.S. for PKA, with an assigned potency of 85 International Units per ampoule.