Non-invasive estimation of hepatic glucose uptake from [18F]FDG PET images using tissue-derived input functions.

PURPOSE: The liver is perfused through the portal vein and hepatic artery. Quantification of hepatic glucose uptake (HGU) using PET requires the use of an input function for both the hepatic artery and portal vein. The former can be generally obtained invasively, but blood withdrawal from the portal vein is not practical in humans. The aim of this study was to develop and validate a new technique to obtain quantitative HGU by estimating the input function from PET images. METHODS: Normal pigs (n = 12) were studied with [18F]FDG PET, in which arterial and portal blood time-activity curves (TAC) were determined invasively to serve as reference measurements. The present technique consisted of two characteristics, i.e. using a model input function and simultaneously fitting multiple liver tissue TACs from images by minimizing the residual sum of square between the tissue TACs and fitted curves. The input function was obtained from the parameters determined from the fitting. The HGU values were computed by the estimated and measured input functions and compared between the methods. RESULTS: The estimated input functions were well reproduced. The HGU values, ranging from 0.005 to 0.02 ml/min per ml, were not significantly different between the two methods (r = 0.95, p < 0.001). A Bland-Altman plot demonstrated a small overestimation by the image-derived method with a bias of 0.00052 ml/min per g for HGU. CONCLUSION: The results presented demonstrate that the input function can be estimated directly from the PET image, supporting the fully non-invasive assessment of liver glucose metabolism in human studies.

Voxel-based analysis of cerebral glucose metabolism in mono- and dizygotic twins discordant for Alzheimer disease.

BACKGROUND: Sporadic Alzheimer disease (AD) is a multifactorial disease to which both genetic and environmental factors contribute. Therefore, twin pairs are useful in studying its pathogenesis and aetiology. Cerebral glucose metabolism has been found to be reduced in AD patients. METHODS: Cerebral glucose metabolism was studied in seven monozygotic (MZ) and nine same-sexed dizygotic (DZ) twin pairs discordant for AD using positron emission tomography. To obtain objective and explorative results concerning differences in glucose metabolism, the analysis was performed utilising modern voxel-based analysis methodology statistical parametric mapping and automated region-of-interest analysis. RESULTS: In the demented MZ and DZ co-twins, cerebral glucose metabolism was extensively reduced compared with controls. The non-demented MZ co-twins showed reduced metabolism in inferior frontal, lateral temporal, parietal and medial temporal cortices as well as in the thalamus, putamen and right amygdala. In contrast, no reductions were found in the non-demented DZ co-twins. The reduction found in the non-demented MZ co-twins may be an indicator of genetic susceptibility to AD.

In vivo measurements of glucose uptake in human Achilles tendon during different exercise intensities.

Muscular contraction and loading of adjacent tendons has been demonstrated to cause increased blood flow and metabolic activity in the peritendinous region. However, it is poorly known to what extent the human tendon itself takes up glucose during exercise. Thus, the purpose of this study was to measure tendon glucose uptake with increasing exercise intensity and to compare it to muscle glucose uptake at the same intensities. Eight young men were examined on three separate days during which they performed 35 min of cycling at 30, 55 and 75 % of VO2max, respectively. Glucose uptake was measured directly by positron emission tomography (PET) with 2-[ (18)F]fluoro-2-deoxyglucose ([18F]FDG). [18F]FDG was injected after 10 min of exercise that was continued for a further 25 min after the injection. PET scanning of the thigh and Achilles region was performed after the exercise. Glucose uptake of the Achilles tendon (AT) remained unchanged (7.1 +/- 1.5, 6.6 +/- 1.1, and 6.0 +/- 1.1 micromol.kg(-1).min(-1)) with the increasing workload, although the glucose uptake in m. quadriceps femoris simultaneously clearly increased (48 +/- 35, 120 +/- 35, and 152 +/- 74 micromol.kg(-1).min(-1), p < 0.05). In conclusion, the AT takes up glucose during exercise but in significantly smaller amounts than the skeletal muscle does. Furthermore, glucose uptake in the AT is not increased with the increasing exercise intensity. This may be partly explained by the cycle ergometry exercise used in the present study, which probably causes only a little increase in strain to the AT with increasing exercise intensity.

Leisure physical activity and various pain symptoms among adolescents.

OBJECTIVES: To investigate the association between leisure physical activity and various pain symptoms in adolescents. METHODS: In this nationwide cohort based cross sectional study in Finland, 698 schoolchildren, 344 girls and 354 boys, aged 10 to 17 years responded to a questionnaire on pain symptoms (neck and shoulder pain, upper back pain, low back pain, upper limb pain, lower limb pain, headache, and abdominal pain) and physical activity habits and also participated in a fitness test. RESULTS: Reported physical activity correlated with measured fitness. Musculoskeletal pains (p = 0.013) (in particular low back pain (p = 0.022), upper limb pain (p<0.001), and lower imb pain (p<0.001)) were found more often in subjects participating in large amounts of leisure physical activity, while non-musculoskeletal pains (p = 0.065) (in particular headache among boys (p = 0.004)) tended to be less common. Co-occurrence of different musculoskeletal pains was common in subjects participating in sports. CONCLUSIONS: In addition to its likely long term health benefits, vigorous physical activity causes musculoskeletal pains during adolescence. This should be considered when tailoring health promotion programmes to adolescents. Also, co-occurrence of musculoskeletal pains may occur as the result of sports activity, which should be considered as a confounder in epidemiological studies on fibromyalgia and related issues.

Ceftriaxone versus vancomycin prophylaxis in cardiovascular surgery.

The efficacy of antibiotic prophylaxis in cardiac surgery was compared between 97 patients receiving a single 2 g dosage of ceftriaxone and 103 receiving 500 mg of vancomycin i.v. every 6 h for 48 h. The overall infection rate was 13.4% in the ceftriaxone and 10.7% in the vancomycin group. Four (4%) wound infections, including one mediastinitis, occurred in the ceftriaxone group and five (5%) in the vancomycin group, with no statistically significant difference. The findings of this study support the adequacy of a simple single dose of ceftriaxone prophylaxis in cardiac surgery, at least in hospitals with low incidence of vancomycin-resistant staphylococcal infections.

Prevention of Type II diabetes in subjects with impaired glucose tolerance: the Diabetes Prevention Study (DPS) in Finland. Study design and 1-year interim report on the feasibility of the lifestyle intervention programme.

UNLABELLED: AIMS/HYPOTHESIS; The aim of the Diabetes Prevention Study is to assess the efficacy of an intensive diet-exercise programme in preventing or delaying Type II (non-insulin-dependent) diabetes mellitus in subjects with impaired glucose tolerance, to evaluate the effects of the intervention programme on cardiovascular risk factors and to assess the determinants for the progression to diabetes in persons with impaired glucose tolerance. METHODS: A total of 523 overweight subjects with impaired glucose tolerance ascertained by two oral glucose tolerance tests were randomised to either a control or intervention group. The control subjects received general information at the start of the trial about the lifestyle changes necessary to prevent diabetes and about annual follow-up visits. The intervention subjects had seven sessions with a nutritionist during the first year and a visit every 3 months thereafter aimed at reducing weight, the intake of saturated fat and increasing the intake of dietary fibre. Intervention subjects were also guided individually to increase their physical activity. RESULTS: During the first year, weight loss in the first 212 study subjects was 4.7 +/- 5.5 vs 0.9 +/- 4.1 kg in the intervention and control group, respectively (p < 0.001). The plasma glucose concentrations (fasting: 5.9 +/- 0.7 vs 6.4 +/- 0.8 mmol/l, p < 0.001; and 2-h 7.8 +/- 1.8 vs 8.5 +/- 2.3 mmol/l, p < 0.05) were significantly lower in the intervention group after the first year of intervention. Favourable changes were also found in blood pressure, serum lipids and anthropometric indices in the intervention group. CONCLUSION/INTERPRETATION: The interim results show the efficacy and feasibility of the lifestyle intervention programme.

The prevalence of low back pain among children and adolescents. A nationwide, cohort-based questionnaire survey in Finland.

STUDY DESIGN: A nationwide, cohort-based cross-sectional questionnaire survey as a part of a population study. OBJECTIVES: To evaluate the prevalence of low back pain among Finnish children and adolescents. SUMMARY OF BACKGROUND DATA: Low back pain is common already in adolescence, but the results concerning sex differences and peak age of the prevalence have been partly controversial. Also, previous studies have been limited to smaller geographic areas. METHODS: The subjects were 594 girls and 577 boys, a total of 1171 children and adolescents. They were pupils of 45 different public schools. Various areas of Finland were included in the sampling process to represent different parts of the country and different living conditions. The subjects completed a validated questionnaire by themselves or with the help of a parent or guardian. The questionnaire was checked by a supervisor when entering the field study. The questionnaire included items that investigated the subjects' past and current low back pain. Low back pain was classified on the basis of timing, duration, and location. Subjects reporting pain in the low back area that interfered with school work or leisure activities during the previous 12 months were defined as having low back pain. RESULTS: The prevalence of back pain was low (1%) among the 7-year-old and 10-year-old (6%) schoolchildren, but increased with age, being 18% both among 14- and 16-year-old adolescents. No gender difference was found. Recurrent or chronic pain was reported by 26% of the boys and 33% of the girls who reported low back pain, and the proportion of recurrent and chronic pains of all low back pain incidents increased with age. CONCLUSIONS: Low back pain is a relatively common complaint at adolescence. In addition, a significant part of the pains are recurrent or chronic already with 14-year-old adolescents.

Physical loading and performance as predictors of back pain in healthy adults. A 5-year prospective study.

We investigated muscle strength, aerobic power, and occupational and leisure-time physical loading as predictors of back pain in a 5-year follow-up study. A cohort of 456 adults aged 25, 35, 45 and 55 years, free of back pain, participated in measurements of anthropometric characteristics, aerobic power and muscle strength characteristics at baseline. The subjects' levels and types of physical activity and occupational physical loading were also determined. At 5 years after the baseline examinations 356 of these subjects (78.1%) were reached by mail, and 262 of them (73.6%) properly completed and returned a questionnaire including a detailed back pain history for the 5 years following the baseline measurements. Of this number 56 subjects (21%) who reported back pain (> 30 on a scale from 0 to 100) and functional impairment during the 5-year follow-up composed the marked back pain group. Other subjects (n = 71, 27%) noting lesser symptoms were included in the mild back pain group; 135 subjects (52%) reported having had no back pain. The subjects with marked back pain were on average taller than the subjects without back pain, while no such difference was found in body mass. Heavy occupational musculoskeletal loading (P = 0.005) and high general occupational physical demands (P = 0.036) predicted future back pain. Leisure-time physical activity, aerobic power or muscle strength characteristics were not predictive of future back pain.

Physical activity, VO2max, and jumping height in an urban population.

We studied the interrelations between, on the one hand, the physical activity (frequency, duration, intensity, and mode) measured by a questionnaire and, on the other, VO2max (submaximal bicycle ergometer test) and the explosive muscle strength (vertical jumping height). A random sample of 774 healthy subjects from the city of Turku participated in this study; the subjects were 25, 35, 45, or 55 yr of age. The VO2max of physically active 55-yr-old female subjects was on the same average level as of 25-yr-old females, who were physically inactive. Correspondingly, the average VO2max of physically active 55-yr-old male subjects was above the average level of 25-yr-old males, who were physically inactive. With the exception of the oldest female study group, the jumping test of physically active subjects gave similar results as those of their inactive counterparts who were 10 yr younger. On the basis of the sports events reported by the subjects, we classified the subjects into five activity mode categories. The mode of activity was significantly associated with VO2max in a three-way ANOVA (P = 0.0027) as well as with the jumping test result (P = 0.0001). Mixed training (includes varied types of exercise for the neuromuscular system) was the most beneficial mode of exercise for developing jumping height. The study suggests that the intensity, frequency, and duration of regular physical activity habits during leisure are associated with both VO2max and the jumping height, and that the jumping height results, in particular, are increased by mixed training.

Carbohydrate ingestion during prolonged running exercise results in an increase of serum cortisol and decrease of gonadotrophins.

We tested the hypothesis that improved availability of energy through carbohydrate ingestion could counteract the documented suppression of pituitary-gonadal function during prolonged exercise. Nine trained males repeated twice a 36 kilometre running exercise with two weeks interval. During the tests the subjects ingested in a randomized single-blind fashion a total of 1050 millilitres of carbohydrate and placebo solutions. The total amount of ingested carbohydrate was 105 grams. Venous blood samples were taken before the exercise (sample A), immediately after exercise (B), and 2 hours later (C). In the B samples plasma glucose was 14% higher (P less than 0.01) and serum cortisol 13% higher (P less than 0.05) in the carbohydrate than in the control trial. In contrast, the level of LH was 18% (P less than 0.05) and that of FSH 11% lower (P less than 0.05) in the carbohydrate than in the placebo trial. Serum testosterone concentration did not differ between the treatment groups. We conclude that carbohydrate ingestion does not counteract the exercise-associated suppression of gonadotrophin secretion, but results in paradoxical increase of serum cortisol and decrease of LH and FSH, in comparison to placebo-treated controls. The higher cortisol level in carbohydrate group may be secondary to higher insulin levels.

Strength characteristics of a healthy urban adult population.

A random sample of 778 subjects representing ages 25, 35, 45 and 55 years were studied for the amount of habitual physical activity, their anthropometric structure, vertical jumping height, trunk extension and flexion torques and dynamic endurance fitness of trunk extension and flexion. The proportion of subjects who were habitually physically active did not change systematically with age. The highest number of physically inactive subjects was found in men and women in the 35-year age group. The results in all the tests used to assess the strength characteristics were statistically significant when related to sex (P less than 0.001) and in all, except the relative maximal isometric torque of trunk extension, when related to age (P less than 0.001). Everyday physical activity was related to the variation in vertical jumping height (P less than 0.001), as well to the dynamic endurance fitness (P less than 0.001) of trunk extension and flexion. The decline in vertical jumping height and dynamic endurance fitness of trunk extension and flexion fitness was found to start at earlier ages than that of relative maximal isometric trunk extension and flexion torques. Dynamic endurance fitness of trunk flexion showed a more pronounced decline with age than trunk extension fitness.

Lumbar muscles: structure and function.

We review new data derived from careful dissection studies on the macroscopic anatomy, innervation and function of the lumbar muscles, as well as information on the fibres in these muscles. The new findings correct previous misconceptions of the functional anatomy of the lumbar muscles. The innervation and function of the erector spinae and multifidus muscles are so different that they cannot be classified as a single unit. The new interpretation of the innervation of multifidus muscle is of importance, for example, for the neurophysiological examination of the lumbar muscles. The relative number of the slow and fast type of muscle fibres in lumbar muscles varies considerably, and selective atrophy of the fast fibres seems to ensue from inactivity, not only in patients with back pain but also in sedentary controls. The atrophy may be corrected by adequate exercise. Both the fibre type composition and degree of atrophy may well influence a person's susceptibility to low back pain arising from the muscles.

Bronchospasm during cardiopulmonary bypass--a potentially fatal complication of open-heart surgery.

Severe bronchospasm at the termination of cardiopulmonary bypass is an unusual but dangerous complication of open-heart surgery. We report two cases. In both of them the final etiology remained unsettled. In one of the cases vigorous and immediate bronchodilatory therapy resulted in a favourable remission. In the second case bronchospasm contributed to a very harmful bulging of the left lung through the opened mediastinal pleura, stretching and damaging the left internal mammary artery graft, which obviously contributed to the fatal outcome. We emphasize especially the following points: 1) a carefully evaluated medical history of patients scheduled for open-heart surgery may reveal some details pointing to an increased risk of bronchospasm during cardiopulmonary bypass; in such cases prophylactic measures may be indicated; 2) immediate vigorous bronchodilatory therapy early at the onset of bronchospasm during the weaning from cardiopulmonary bypass may reverse the alarming situation.

Histological pattern and changes in extracellular matrix in aortic dissections.

Samples from 34 patients were studied both histologically and immunocytochemically by the indirect biotin-avidin peroxidase technique to analyse the distribution of the extracellular matrix components (type IV collagen, fibronectin, types I and III collagens) in dissection of the aorta. Most showed defects in type IV collagen around medial smooth muscle cells. Defects in smooth muscle cell basement membrane were found throughout the media in cystic medial degeneration and in medionecrosis, whereas in atherosclerosis such unlabelled areas were found only above advanced atherosclerotic plaques. In aortitis other defects in the smooth muscle cell basement membrane were found in areas of inflammatory infiltrates. In all of these conditions similar defects in fibronectin expression were also found. No defects in the expression of interstitial collagens type I and III were seen in the dissecting aortas. Moreover, cystic medial degeneration, medionecrosis, and atherosclerosis were characterised by intense staining of these interstitial matrix components. In the pathogenesis of the aortic dissection local changes in the basement membranes of the medial layer may be important.

Diagnostic difficulties in aortic dissection. Retrospective study of 89 surgically treated patients.

During the years 1964-1985, a total of 89 patients were operated on for aortic dissection: 55 were treated for proximal dissection and 34 for distal dissection of the aorta. In the former group a diagnostic delay more than 24 hours after hospitalization occurred in 17 instances (31%), and in the latter group in 18 instances (53%). The most common incorrect diagnosis in both groups was myocardial infarction. In the proximal group of aortic dissection, other cardiac diseases suspected were pericarditis, endocarditis and congestive heart failure. In the distal group of aortic dissection, acute surgical abdomen was the most common cause of incorrect diagnosis after ischaemic heart disease. Four case reports with diagnostic delay are presented.

Surgical treatment of aortic dissection in 60 patients.

During the years 1964-82 a total of 60 patients underwent surgery for aortic dissection. Forty of them were males, with a mean age of 48.8 years (22 to 69) and 20 were females, with a mean age of 49.0 years (31 to 65). Forty-five patients were operated in an acute stage of aortic dissection and 15 patients in a chronic stage of this disease. The mortality rate of patients operated on for acute dissections was 51.1% and of patients with a chronic dissection 13.3%, the over-all hospital mortality rate being 41.7%. Cardiac and haemorrhagic complications were the commonest cause of death. Among the 35 operative survivors, there were seven late deaths (11.7%); 4 patients died of cardiovascular causes. The mean follow-up time was 6.1 years (2.7 to 13.4). Twenty-six long-term survivors were re-examined in the hospital.

Late results of the surgical treatment for aortic dissections.

The results of 32 patients who had undergone surgery for aortic dissections were analyzed. Twenty-six patients were examined in hospital during the follow-up study while one patient refused the examination and 5 others had succumbed. The average follow-up was 42.6 months. Late functional status was generally good. Resuspension of the aortic annulus for incompetent aortic valves in type I and II dissections resulted in grave aortic regurgitation and death in one case, and in mild valvular incompetence in another case, while 5 patients had competent valves after resuspension. Computed tomography (CT) and angiographic studies frequently revealed residual changes such as double lumen of the aorta. Five subsequent aortic aneurysms were discovered, 4 of them having been reoperated after the study was completed. Periodical follow-up and screening of the aorta of operative survivors is recommended.