A maternal diet of fatty fish reduces body fat of offspring compared with a maternal diet of beef and a post-weaning diet of fish improves insulin sensitivity and lipid profile in adult C57BL/6 male mice

AIM

The maternal diet during pregnancy and lactation may affect the long-term health of the offspring. Our aim was to study how a fish or meat diet perinatal and after weaning affects body composition, insulin sensitivity and the profile of n-3 and n-6 polyunsaturated fatty acids (PUFAs) in breast milk, fat depots, skeletal muscle and liver in male adult mice offspring.

METHODS

During gestation and lactation, C57BL/6 dams were fed a herring- or beef-based diet. Half of the pups in each group changed diets after weaning. In offspring, body composition measured by DEXA, plasma lipid profile and insulin sensitivity measured by euglycemic clamp or QUICKI were monitored to adulthood. Analysis of total FAs by GC-MS were performed in the diet, breast milk and in different tissues.

RESULTS

At 9 week of age, offspring of herring-fed dams had less body fat than offspring of beef-fed dams. Mice fed herring after weaning had increased insulin sensitivity at 15 week of age, reduced total plasma cholesterol and triglyceride levels, and compared with beef-fed mice, larger interscapular brown adipose tissue depots. The FA composition of the maternal diet was mirrored in breast milk, and the herring diet significantly affected the FA profile of different tissues, leading to an increased content of n-3 PUFAs.

CONCLUSION

A herring-based maternal diet reduces body fat in the offspring, but the insulin sensitivity, plasma lipids and amount of brown adipose tissue are affected by the offspring's own diet; the herring diet is more beneficial than the beef diet.

Stretch-shortening cycle muscle power in women and men aged 18-81 years: Influence of age and gender

This study explored the age-related deterioration in stretch-shortening cycle (SSC) muscle power and concurrent force-velocity properties in women and men across the adult life span. A total of 315 participants (women: n = 188; men: n = 127) aged 18-81 years performed maximal countermovement jumps on an instrumented force plate. Maximal SSC leg extension power expressed per kg body mass (Ppeak) was greater in men than in women across the adult age span (P < 0.001); however, this gender difference was progressively reduced with increasing age, because men showed an ∼50% faster rate of decline in SSC power than women (P < 0.001). Velocity at peak power (VPpeak) was greater in men than in women (P < 0.001) but declined at a greater rate in men than in women (P = 0.002). Vertical ground reaction force at peak power (FPpeak) was higher in men than in women in younger adults only (P < 0.001) and the age-related decline was steeper in men than in women (P < 0.001). Men demonstrated a steeper rate of decline in Ppeak than women with progressive aging. This novel finding emerged as a result of greater age-related losses in men for both force and velocity. Consequently, maximal SSC power production was observed to converge between genders when approaching old age.

Physical activity, sports participation and aerobic fitness in children who have undergone surgery for congenital heart defects

AIM

To investigate physical activity, sports participation and aerobic fitness in children who have undergone surgery for congenital heart defects.

SUBJECTS AND METHODS

Children who had undergone surgery for congenital heart defects and healthy controls in the Gothenburg area were invited to participate in the study. All participants were aged 9-11 or 14-16 years. The activity monitor ActiReg was used to assess physical activity. Participants were interviewed about their participation in sports and performed a maximal exercise test on a bicycle with measured oxygen uptake.

RESULTS

A total of 32 and 25 patients, and 61 and 45 controls, in the two age-groups were included, respectively. The patients had a wide range of severity of congenital heart defects. The physical activity level was similar in the patients and the controls. The rate of sports participation was high for both patients and controls; 80-94% of all participants took part in sports at least once a week. The majority of the patients were considered to have at least a moderate level of aerobic fitness.

CONCLUSIONS

Although children who have undergone surgery for congenital heart defects have a similar level of physical activity compared with that of healthy children, some of them may require support to participate in exercise and vigorous physical activity.

Serum iron concentration as a tool to measure relative iron absorption from elemental iron powders in man

OBJECTIVE

To present a new method for measuring the relative bioavailability (RBV) of commercial elemental iron powders by investigating induced changes of serum iron concentration (S-Fe) in relation to ferrous sulphate (FeSO4). Earlier studies have shown that in a group of subjects there is good agreement between the increase in S-Fe and the amount of iron absorbed from a simple iron salt as FeSO4.

METHODS

The study included two groups of male blood donors (n=2 x 16 subjects) who were served three meals with an interval of approximately nine weeks between each one. In one group the meal was fortified with reduced iron, ferrous sulphate or no iron at all. In the other group the meal was fortified with electrolytic iron, ferrous sulphate or no iron. The S-Fe increase was followed for 6 h. Studying the non-iron meals was necessary so that the basal diurnal variation in the S-Fe during the six hours could be measured and subtracted.

RESULTS

The mean S-Fe increase calculated as the area under the curve (AUC) from the reduced iron (RBV=0.43) and the electrolytic iron (RBV=0.73) differed significantly from the AUC following FeSO4 (p=0.002 and p=0.021, respectively). The difference between the reduced and the electrolytic iron was also statistically significant (p=0.036).

CONCLUSION

Measuring increases in S-Fe could be a reliable and simple method to determine the RBV in comparative studies of elemental iron powders in relation to FeSO4.

The effect of the converting enzyme inhibitor SQ 20.881 on kinins, renin-angiotensin-aldosterone and catecholamines in relation to blood pressure in hypertensive patients

Nine sodium replete hypertensive patients with normal or high plasma renin activity (PRA) were given SQ 20.881, 1 mg/kg intravenously BP fell significantly within 20 min and reached its lowest level after 60 min. Blood kinins showed a minor but significant decrease after 60 and 105 min. Plasma angiotensin II was markedly reduced after 15 and 60 min. PRA was significantly increased after 15-105 min. Plasma aldosterone was reduced at 60 min in eight patients and slightly increased in one. Plasma noradrenaline increased after 15 min, whereas adrenaline decreased after 60 min. These results indicate that the reduction of BP following inhibition of converting enzyme by SQ 20.881, 1 mg/kg, is not related to reduced degradation of kinins but rather to decreased formation of angiotensin II. Angiotensin II appears to be of importance for the maintenance of BP in sodium replete hypertensive patients with normal or high PRA.

Hemodynamic effects of calcium channel blockers in essential hypertension

Calcium channel blockers decrease blood pressure in essential hypertension due to a marked reduction of systemic vascular resistance (arteriolar tone). They also dilate conducting arteries but have no venodilatory effect in antihypertensive doses. With the dihydropyridines (e.g. nifedipine) and diltiazem there is a transient increase in heart rate and cardiac output but this is not observed with verapamil. The vasodilatory responsiveness in the resistance vessels to calcium channel blockers is selectively enhanced in patients with established essential hypertension but not in the early borderline phase of hypertension. During treatment with chlorthalidone, atenolol, acebutolol or nitrendipine for four to six weeks the reduction of blood pressure is accompanied by a selective decrease in the vasodilatory responsiveness to calcium channel blockers.

The importance of bioavailability of dietary iron in relation to the expected effect from iron fortification

BACKGROUND

The most common method of combating iron deficiency is iron fortification, especially in developing countries. However, few studies have shown a significant effect on iron status following iron fortification of low bioavailability diets.

OBJECTIVE

To investigate how iron fortification and dietary modifications affect iron absorption and rates of changes in iron stores.

METHODS

Research has made it possible to predict both iron absorption and the effects of iron fortification and diet modifications on iron stores using recently developed algorithms. Iron absorption and rate of change in iron stores were calculated from nine diets representing a broad range of iron bioavailability and iron contents. The calculations were related to the main target group for iron fortification, that is, women of reproductive age having empty stores but normal haemoglobin concentrations.

RESULTS

As the only measure, iron fortification has practically no effect on iron status if the original diet has low bioavailability. However, after dietary modifications such a diet shows a positive effect on iron stores. The combined action of fortification (6 mg/day) and modest bioavailability changes in a low bioavailability diet results approximately in 40 and 70% greater increases in iron stores than through iron fortification or dietary modification alone.

CONCLUSIONS

It is difficult to achieve good effects on iron status from iron fortification as the only measure if the diet has low bioavailability. Both dietary modifications as well as iron fortification are required to improve effectively the iron status of a population.

Capturing the onset of the common cold and its effects on iron absorption

Hypoferremia is a well-known response to infections and inflammatory disorders. It seems to be managed by the key mediator of iron kinetics, hepcidin. There are several studies on induced-acute phase reactions. However, to our best knowledge there are no previous published reports on the outbreak of a common cold and its initial effect on iron kinetics. The objective of this case report is to describe such an observation. From an apparently healthy state in the morning we observed, in a 28-year-old male, every hour for 6 h the outbreak of a common cold and the modulations in the levels of serum iron (S-Fe) and interleukin-6 (IL-6). Despite a 100 mg oral iron loading there was a substantial reduction in S-Fe, which seemed to precede the IL-6 peak. Interestingly, this observed succession is in conflict with the proposed infection chain of order in which IL-6 stimulates hepcidin induction.

Measurements of eosinophil activation before and after food challenges in adults with food hypersensitivity

BACKGROUND

Objective assessment of inflammatory reactions in the gastrointestinal tract could be useful in the diagnosis of food hypersensitivity. The aim of the present study was to investigate the involvement of eosinophils and mast cells in the inflammatory response of patients with food hypersensitivity before and after food challenges.

METHODS

Eleven patients (4 with IgE-mediated allergy and 7 without) with food hypersensitivity and positive double-blind, placebo-controlled food challenge were subjected to food challenge in a single-blinded fashion. Four subjects with no known food hypersensitivity were recruited as controls. Placebo was given after a 1-week washout period followed by an active dose. Stool, urinary and serum samples were collected and symptoms were recorded in a diary. Fecal samples were analyzed for eosinophil protein X (F-EPX) and tryptase; urinary samples for EPX (U-EPX) and leukotriene E4 (U-LTE4) and serum samples were analyzed for eotaxin and food-specific IgE antibodies.

RESULTS

Patients with IgE-mediated food allergy had increased levels of F-EPX compared to controls and tended to have lower serum levels of eotaxin compared to non-allergic patients and controls. U-LTE4 was significantly higher in allergic patients compared to non-allergic patients after challenge. Moreover, F-EPX correlated to U-LTE4 (p = 0.011). Reported symptoms, abdominal pain, distension, flatulence and nausea were similar in the allergic and non-allergic patients.

CONCLUSION

The results strongly indicate that eosinophils are activated in the gastrointestinal tract of food-allergic patients but not in patients with non-allergic food hypersensitivity. Due to the inconsistent pattern of symptoms after placebo and active food challenge, it was not possible to relate the levels of inflammation markers to the recorded symptoms.

Dietary problems in patients with severe chronic obstructive pulmonary disease

BACKGROUND AND AIMS

Low body weight and low fat-free mass-index (FFMI) are common in patients with severe chronic obstructive pulmonary disease (COPD). Several factors seem to contribute. The aims of the present observational study were to investigate dietary problems in patients with severe COPD and to compare dietary problems to nutritional status, energy intake and smoking habits.

METHODS

Nutritional status was assessed in 73 stable outpatients using body mass index and FFMI by single-frequency bioelectrical impedance. Lung function, smoking habits, energy intake and dietary problems were also assessed.

RESULTS

The most frequently reported dietary problems were 'anorexia', 'dyspeptic symptoms other than diarrhoea', 'slimming', 'fear of gaining weight', 'dyspnoea', 'diarrhoea', 'depression, anxiety, solitude'. Smoking habits and gender had impact on the kind of dietary problems reported. Reporting two dietary problems correlated to low FFMI, whereas reporting one or more dietary problems correlated to decreased energy intake.

CONCLUSION

Dietary problems are common in the group studied and related to smoking habits and gender. Dietary problems affect energy intake and FFMI negatively. It is important to recognize dietary problems and to offer intervention of the dietary problems as a part of the dietary intervention.

Energy expenditure in underweight chronic obstructive pulmonary disease patients before and during a physiotherapy programme

OBJECTIVE

To investigate how total daily energy expenditure (TEE) changes when underweight patients with chronic obstructive pulmonary disease (COPD) enters a physiotherapy programme.

DESIGN

Prospective intervention study.

SETTING

Sahlgrenska University Hospital, Göteborg, Sweden.

SUBJECTS

Fifteen patients with severe COPD and BMI<21 kg/m(2) were recruited consecutively at the outpatient COPD unit at the Department of Respiratory Medicine. Fourteen patients completed the whole study.

INTERVENTION

TEE was assessed by the doubly labelled water method in a 2-week control period and during 2 weeks of physiotherapy. Energy intake was assessed using 7-day dietary record during control and physiotherapy period.

RESULTS

Mean TEE during physiotherapy period was 500 kJ (6%) lower than during control period but the difference was not statistically significant. Ten of the 14 patients had lower and four had higher TEE. Mean energy intake during the physiotherapy period did not change from the control period (7700 vs 7600 kJ/day).

CONCLUSIONS

Since underweight patients with COPD may show variable TEE during physiotherapy compared to a control period, an assessment of individual energy requirements is recommended.

Obesity, dietary pattern and physical activity among children in a suburb with a high proportion of immigrants

BACKGROUND

Obesity among children is a growing problem. Interventions should be planned to meet needs in different cultural settings. The objective of this study was to explore dietary patterns, physical activity and perceptions of relationships between life-style and health among children in a suburb with low socio-economic status and a high proportion of immigrants and refugees.

METHODS

All children (n = 114) in Grades 5 and 6, aged 11 to 12 years, at a local Swedish school were invited, 112 participated. Food and exercise habits and perceptions on health and body image were assessed by a validated questionnaire and an interview. Height and weight were measured and risk for passing BMI 25 and 30 kg/m(2), respectively at the age of 18 was calculated.

RESULTS

Thirty-one percent of the children were obese or overweight. Thirty-four percent spent more than 3 h daily watching TV or using computer, a behaviour, which clustered with excess intake of sweet drinks and habitually skipping breakfast. Only about half of the children believed that their life-style could affect their health. The results show that low socio-economic status and migration are proxies for overweight and obesity.

CONCLUSIONS

Obesity, unhealthy living and a low awareness of relations between life-style and health call for action, for culturally sensitive prevention and treatment approaches.

Double-blind placebo-controlled challenges for peanut allergy the efficiency of blinding procedures and the allergenic activity of peanut availability in the recipes

BACKGROUND

A firm diagnosis of double-blind placebo-controlled food challenge (DBPCFC) would facilitate the diagnosis in patients with uncertain history of reaction. Guidelines are lacking for an upper provoking dose and how to hide high concentrations of peanuts.

AIM

To develop and evaluate a double-blind recipe with minimum 10% of peanut. To compare the recipe with published recipes regarding blindness, taste, texture and immunoglobulin (Ig)E antibody binding to peanut.

METHODS

A recipe (I) with 10% of peanut was developed evaluated and used in DBPCFC. The challenges were followed by development of a concentrated recipe (II) (15% peanut, 25% fat). Recipe II was compared with the only published recipe (III) (11% peanut, 7% fat) regarding taste, texture and availability of peanut. Recipe IV (12% peanut, 10% fat) was developed using the same methods. The binding of IgE in the recipes was measured using an inhibition method.

RESULTS

During challenges, one patient reacted after 4 g, emphasizing the need for blinding recipes containing high doses of peanut. Evaluation between recipes II and III, only recipe II was regarded as blind by the taste panels. A tenfold lower availability of peanut protein in the recipe II was found at 50% of inhibition. Recipe IV had a better IgE binding that did not differ from the original peanut extract.

CONCLUSION

The peanut taste and texture can be hidden in a challenge medium. The fat content was important for the availability of the allergenic protein in challenges. The availability of allergens must be taken into consideration when used for DBPCFC.

Specific immunoglobulin E antibodies to peanut over time in relation to peanut intake, symptoms and age

The clinical outcome of peanut allergy and some factors associated with development of peanut allergy remain unsolved. It has not been clarified to what extent peanut intake affects immunoglobulin (IgE) antibody formation in peanut sensitized individuals. The aim of the study was to investigate the development of peanut hypersensitivity in children and adolescents with specific IgE antibodies to peanut, using questionnaires and current serum tests and comparing it to information obtained 5-6 yr earlier, to investigate how peanut intake during this period related to subject age, IgE antibody levels and symptoms and to investigate what information this patient group was given at the time of diagnosis regarding avoidance of peanut related food. All patients with detectable peanut-specific IgE antibodies investigated during 1994-1996 deriving from two allergy laboratories in the western region of Sweden were traced and reinvestigated (n=132). A total of 111 subjects (63 with peanut allergy and 48 peanut sensitized) participated in the questionnaire. Eighty-six of them consented to be enrolled in a further interview and renewed testing of specific IgE antibody to peanut 5 yr later. All tests were done using the Pharmacia CAP system. Increased IgE antibody levels during follow-up was related to age; subjects 0-6 yr at initial test occasion were more likely to have higher IgE antibody class than the older individuals (p=0.018). Exposure to peanut during the study, i.e. 5-6 yr since diagnosis, did not seem to affect the result. During the follow-up period, 29 out of 86 (34%) increased their IgE antibody class. At the second test occasion the remaining subjects had similar (28%) or lowered (38%) levels of IgE antibodies. Exposure to peanut during follow-up was more common in subjects with IgE antibody class 1-3 compared to subjects with high value (> 3) at the initial test (p=0.003). Reported symptoms during follow-up were also more common in subjects with initially high IgE antibody value. Individuals with initially high IgE antibodies to peanut had been given more information about peanut allergy and cross-reacting allergens than other individuals. The subjects over 6 yr of age showed a decrease in peanut-specific IgE class over a 5-yr period. Together with the literature, our result suggest that follow-up and renewed testing is recommended, since there may be a change in IgE antibody classes and clinical sensitivity over time. Even in Sweden, with a low consumption of peanuts, the youngest individuals with peanut sensitization experienced a similar course of events that has been reported in other countries.

Introduction of food during the infant's first year: a study with emphasis on introduction of gluten and of egg, fish and peanut in allergy-risk families

AIM

The aim of the current study was to retrospectively examine introduction of food during the first year in a representative sample of Swedish children. A secondary aim was to study how parents with history of atopy introduced food to their infants.

METHODS

Data derive from 467 infants who visited child health centres in three different counties in Sweden for health check-up at 12 mo of age. The parents were asked to fill in a questionnaire about breastfeeding and/or formula feeding, time of introduction of weaning food focusing on cow's milk, follow-on formula, porridge, fish and egg. Questions regarding hypersensitivity in the family, peanut consumption of mother as well as in the child, and questions about number of siblings, ethnic background and parental education were included.

RESULTS

Compliance with suggested introduction of gluten-containing food was low; as many as 45% had avoided gluten until 6 mo of age, instead of introducing gluten between 4 and 6 mo. Only 33% of parents with stated family hypersensitivity avoided giving their child fish and 23% avoided egg during the first year, even though this recommendation was present at the time of the study. Almost 50% of all mothers had avoided peanuts during pregnancy even though there was no such advice. The avoidance of peanut was not connected to hypersensitivity in the family.

CONCLUSION

These results suggest that time of introduction of gluten was not in accordance with the current recommendation. The results imply that there is a need to follow up if and how this feeding information is distributed to parents with infants and also to sharpen the information to the right target groups, otherwise implementation of preventive strategies will be less useful.

Assessment of habitual meal pattern and intake of foods, energy and nutrients in Swedish adolescent girls: comparison of diet history with 7-day record

OBJECTIVE

To compare the diet history (DH) method to an estimated 7-day record (7-d) concerning meal pattern and intake of foods, energy and nutrients.

DESIGN

After the DH interview, subjects completed the 7-d.

SETTING

School setting, Göteborg, Sweden.

SUBJECTS

A total of 51 adolescent girls (15-16 y) recruited from 634 girls participating in The Göteborg Adolescence Study.

RESULTS

Two-thirds of the girls had identical or similar main meal pattern, while the number of in-between meals was higher using DH (P<0.001). Breakfast was the meal that agreed best and dinner during weekends. Energy intake (EI) was 8% higher in DH compared to 7-d (P=0.056). The ratio EI to basal metabolic rate was 1.35 (1.14, 1.65) using DH and 1.26 (1.08, 1.52) using 7-d, indicating under-reporting in both methods. Intake of vegetables, juice, sweets, soft-drinks and jam did not differ between the methods, but for the rest of the intake DH estimates were higher (P<0.05). The calculated nutrient intake was higher by DH, with exception of fat and sucrose. For the main food groups, energy and nutrients, except alcohol, ranking was similar between the methods. Adjusted for EI (10 MJ), intake of fat and sucrose were lower and protein, calcium and fibre were higher by DH (P<0.01). EI did not differ for lunch and dinner, but was higher in breakfast and in-between meals using DH. Intake of foods and nutrients in lunches and meat and fish for lunch and dinner did not differ.

CONCLUSIONS

The diet history seems to work well as a reference method for dietary assessments in this age group.

SPONSORSHIP

The Swedish Medical Research Council (project B94-19X-04721-19A), the Swedish Mill Industry, The Wilhelm and Martina Lundgren Foundation and The Swedish Nutrition Foundation.

Meal pattern, food choice, nutrient intake and lifestyle factors in The Göteborg Adolescence Study

OBJECTIVE

To relate meal pattern of Swedish adolescents to food choice, nutrient intake and other lifestyle factors.

DESIGN

Cross-sectional study including diet history and interview about smoking, ethnicity, social factors and retrospectively collected data of menarche and growth.

SETTING

School setting, Göteborg, Sweden.

SUBJECTS

A total of 611 boys and 634 girls in grade 9 (15-16 y).

RESULTS

The majority of the students, 65% of the boys and 52% of the girls, consumed three main meals daily. The in-between meals, however, contributed the major part of the energy intake. The energy intake was 12.9+/-3.5 MJ (mean+/-s.d.) for boys and 9.0+/-2.5 MJ for girls. Irregular breakfast eating, 12% of the boys and 24% of the girls, was related to negative lifestyle factors where smoking was the strongest, odds ratio 3.8 (95% CI: 2.6-5.4) and to irregular intake of lunch and dinner. These boys and girls had a food choice including a higher percentage of energy from snack food (26% vs 20% and 19% in boys and girls respectively, all P<0.001), mostly consumed between the main meals. These groups had significantly lower intakes of micronutrients, but higher intakes of sucrose and alcohol compared to the groups with regular breakfast intake. Girls omitting breakfasts and lunches (8%) also had a less healthy food choice and the poorest nutrient intake. These girls had matured earlier, with menarche age of 12.2+/-1.1 y vs 12.9+/-1.0 y (P<0.001) in girls with regular main meal intake.

CONCLUSIONS

Meal pattern with omission of breakfast or breakfast and lunch was related to a clustering of less healthy lifestyle factors and food choice leading to a poorer nutrient intake.

SPONSORSHIP

The Swedish Medical Research Council (project B94-19X-04721-19A), the Swedish Mill Industry and the Wilhelm and Martina Lundgren Foundation.

Energy intake in Swedish adolescents: validation of diet history with doubly labelled water

OBJECTIVE

To compare habitual energy intake (EI) estimated from diet history (DH) with total energy expenditure (TEE) measured with doubly labelled water (DLW) in adolescents.

DESIGN

DH included a detailed questionnaire and an interview. TEE was measured during a 14-day period. Adequate (AR), under- (UR) and over-reporters (OR) were defined from the ratio EI/TEE: AR 0.84-1.16, UR <0.84 and OR >1.16.

SETTING

Participants were recruited from grade 9 in a compulsory school in Göteborg, Sweden. All data were collected at school and DLW dosages were distributed at Sahlgrenska University Hospital.

SUBJECTS

A total of 35 adolescents (18 boys, 17 girls), 15.7 (0.4) y.

RESULTS

EI was 11.0 (3.6) MJ and TEE was 11.4 (2.1) MJ (P=0.42). DH was able to rank EI compared to TEE (Spearman's r=0.59, P< or =0.001). For girls, EI was 18% lower (P=0.0067) and for boys, EI was 7% higher (P=0.26) compared to TEE. The 95% limits of agreement for difference between TEE and EI were -5.6 to 6.5 MJ. In total, 20 subjects were defined as AR (57%), nine as UR (26%) and six as OR (17%). Energy from in-between meals was 33% lower (P=0.0043) in UR girls and 57% higher (P=0.026) in OR boys, compared to adequate reporting girls and boys, respectively. In UR girls, energy-adjusted intake (10 MJ) of specific foods did not differ significantly, fat was lower and carbohydrate and vitamin C were higher compared to AR girls (all P<0.05). OR boys had no significant differences in food and nutrient intake in 10 MJ compared to AR boys.

CONCLUSION

The diet history was able to capture EI for the group and to rank subjects. There was a wide individual range in reporting-accuracy related to gender.

SPONSORSHIP

The Ingabritt and Arne Lundberg Foundation, The Wilhelm and Martina Lundgren Foundation.

GH is needed for the maturation of muscle mass and strength in adolescents

The postpubertal period and the early years of adulthood may be of importance for continuing tissue maturation of importance in adulthood and aging. An example of this is the peak bone mass. This study has evaluated the importance of GH for lean mass and muscle strength in adolescents and young adults. GH treatment was discontinued in 40 adolescents aged 16-21 yr with GH deficiency of childhood onset. Measurements of isometric and isokinetic knee-extensor and flexor strength, handgrip strength, lean body mass, fat-free mass, and total body nitrogen were performed annually for 2 yr. Two hundred fifty healthy adolescents were randomly selected for prospective measurements of lean mass and handgrip strength between the ages of 17 and 21 yr. In the adolescents with continuing GH deficiency, lean body mass decreased, compared with the patients defined as having sufficient endogenous GH. The isometric strength in knee flexors increased in the sufficient endogenous GH group and was unchanged in the GH deficiency group during the 2 yr off GH treatment (between group, P < 0.05). The mean and peak handgrip strength increased on average by 9-15% in the group with sufficient endogenous GH and was unchanged in those with GH deficiency (P < 0.05). Lean body mass and handgrip strength (both, P < 0.001) increased in both the healthy boys and girls who were followed for 4 yr with a more marked increase in the boys. The mean increase in handgrip between the age of 17 and 21 yr was 7-9%. The increased lean mass and improved muscle performance seen in healthy adolescents did not occur in adolescents with GH deficiency. These findings suggest that GH is of importance for the maturation of lean mass and muscle strength in adolescents and young adults.

Specific IgE antibodies to peanut in western Sweden--has the occurrence of peanut allergy increased without an increase in consumption?

BACKGROUND

Sensitization to peanut has seldom been investigated in Sweden. Therefore, all IgE-specific tests for peanut during a 5-year period were reviewed to study the relation between the levels of specific IgE antibody to peanut and age, sex, symptoms, and other atopic manifestations.

METHODS

All serum samples were analyzed for IgE antibodies to peanut in relation to sex, age, clinical reactions, and other food allergens. A subgroup was asked to answer a questionnaire about symptoms and atopic manifestations in relation to IgE antibody levels.

RESULTS

During the study period, 2417 tests were made for peanut. There was an increased prevalence of detectable IgE antibodies during the years studied. More than 80 individuals under 2 years of age were sensitized to peanut. In the subgroup, individuals with detectable IgE antibodies reported a shorter reaction time after eating peanuts than individuals with normal IgE antibody levels (P < 0.05).

CONCLUSION

The reaction pattern to peanuts in Sweden is similar to that in many other countries despite a reported steady and low consumption. The severity of symptoms was connected to age and IgE antibody level. Patients with normal or low IgE antibody levels were not always free of symptoms even though their risk of allergic symptoms was reduced.

Cancer risk in Swedish women: the relation to size at birth

The relationship between fetal growth as indicated by weight and length at birth, and cancer risk in 1080 adult Swedish women was examined. Birth factors were retrieved from original midwife records for the years 1914, 1918, 1922 and 1930, and primary cancer cases were identified by matching with national and regional cancer registries through the year 1998. A positive and statistically significant increased risk for cancer was found with increasing birth weight or birth length for all site cancer and non-hormone related cancer, defined as all cancer sites excluding breast, uterus and ovary. Addition of factors suspected to influence cancer risk, maternal proteinuria, birth order, own parity and age at menarche, did not attenuate this relation. Previously only breast cancer has been reported to be related to size at birth in adult women and this is the first study to report that cancer sites other than the major hormone-related sites may be influenced by size at birth, as measured by either weight or length at birth; these findings warrant further investigation.

Blood pressure and hypertension in middle-aged women in relation to weight and length at birth: a follow-up study

OBJECTIVES

To examine the relationship between indicators at birth and adult blood pressure and risk for developing hypertension at two age levels.

DESIGN

Original midwife records of 438 women born at term participating in a prospective population study in Göteborg, Sweden with blood pressure and hypertension assessment at both 50 and 60 years of age.

RESULTS

Systolic blood pressure at both age levels showed a U-shaped relationship to weight and length at birth. Hypertension prevalence at 60 years was significantly and inversely related to both weight and length at birth, but not at 50 years. Significantly higher risk for hypertension was found in the lowest birth weight quintile [odds ratio (OR) = 2.0, 95% confidence interval (CI) 1.1-3.8] and lowest birth length tertile (OR = 1.8, 95% CI 1.1-3.0), in relation to the middle quintile/tertile, with or without adjustment for adult body size (as body mass index), at 60 years but not at 50 years. At 50 years, hypertension risk decreased by 3% (95% CI 0.92-1.01) for every 100 g increase in birth weight and 6% (95% CI 0.83-1.05) per cm birth length. At age 60 years, hypertension risk decreased by 4% (95% CI 0.92-0.99) per 100 g birth weight and 10% (95% CI 0.81-0.99) per cm length.

CONCLUSIONS

Size at birth was a predictor of hypertension risk in women at 60 years but not 50 years. This study supports the hypothesis that poor fetal growth, as measured by low weight or length at birth, may contribute to the development of hypertension in later life and that this relationship became stronger with age.

Poor agreement between self-reported birth weight and birth weight from original records in adult women

Data from an ongoing prospective population study of women in Göteborg, Sweden, were used to assess agreement between self-reported birth weight and birth weight obtained from original delivery records of women aged 44-60 years. Of the eligible population with traced delivery records (n = 693), only 28% (n = 192) could report their own birth weight. Spearman correlation between self-reported birth weight and birth weight from original records was r = 0.76. However, a difference plot, with limits of agreement at -1,028 to 1,038 g (95% confidence limits: lower limit, -1,157 to -901 g, upper limit, 910 to 1,166 g) revealed poor agreement between methods. Of the self-reported birth weights, 53% were in error by 250 g or more, and 31% were positively or negatively discordant by 500 g or more. Application in an analysis of cardiovascular risk factors in adulthood found conflicting results between self-reported and recorded birth weights. Low reporting rate, poor reporting accuracy, and misleading findings in application led to the conclusion that self-reported birth weights from middle-aged women would not be a satisfactory replacement for birth weights from original records.

Iron stores and haemoglobin iron deficits in menstruating women. Calculations based on variations in iron requirements and bioavailability of dietary iron

BACKGROUND

Iron stores and haemoglobin iron deficits in menstruating women can be calculated from body iron losses and absorption of dietary iron using recently developed methods.

OBJECTIVE

To examine iron balance (iron status) expressed as body iron stores or haemoglobin iron deficits in menstruating women from amounts of iron lost (iron requirements) and amounts of dietary iron absorbed. Calculations are made both of stationary states and of the rate of changes in iron stores (iron status) when any of the two main factors determining iron balance are changed.

DESIGN

The study is based on (1) previous and new equations describing relationships between iron absorption, iron requirements (losses), iron stores and/or haemoglobin deficits and (2) published data on iron requirements and their variation in menstruating adult women.

RESULTS

Both iron stores and haemoglobin iron deficits are strongly related to iron requirements and absorption of dietary iron and follow the same equations during states of iron repletion and iron deficiency. When, for example, increasing or decreasing the bioavailability of the dietary iron, about 90% of the change in iron stores will occur within 1 y.

CONCLUSIONS

There are strong relationships between iron requirements, bioavailability of dietary iron and amounts of stored iron. The observations that a reduction in iron stores and a calculated decrease of haemoglobin iron had the same increasing effect on iron absorption suggest that the control of iron absorption is mediated from a common cell, that may register both size of iron stores and hemoglobin iron deficit, eg the hepatocyte. European Journal of Clinical Nutrition (2000) 54, 650-657.

Prediction of dietary iron absorption: an algorithm for calculating absorption and bioavailability of dietary iron

BACKGROUND

Dietary iron absorption from a meal is determined by iron status, heme- and nonheme-iron contents, and amounts of various dietary factors that influence iron absorption. Limited information is available about the net effect of these factors.

OBJECTIVE

The objective was to develop an algorithm for predicting the effects of factors known to influence heme- and nonheme-iron absorption from meals and diets.

DESIGN

The basis for the algorithm was the absorption of iron from a wheat roll (22.1 +/- 0.18%) containing no known inhibitors or enhancers of iron absorption and adjusted to a reference dose absorption of 40%. This basal absorption was multiplied by the expected effect of different amounts of dietary factors known to influence iron absorption: phytate, polyphenols, ascorbic acid, meat, fish and seafood, calcium, egg, soy protein, and alcohol. For each factor, an equation describing the dose-effect relation was developed. Special considerations were made for interactions between individual factors.

RESULTS

Good agreement was seen when measurements of iron absorption from 24 complete meals were compared with results from use of the algorithm (r(2) = 0.987) and when mean iron absorption in 31 subjects served a varied whole diet labeled with heme- and nonheme-iron tracers over a period of 5 d was compared with the mean total iron absorption calculated by using the algorithm (P = 0.958).

CONCLUSIONS

This algorithm has several applications. It can be used to predict iron absorption from various diets, to estimate the effects expected by dietary modification, and to translate physiologic into dietary iron requirements from different types of diets.

Sociodemographic characteristics influencing birth outcome in Sweden, 1908-1930. Birth variables in the Population Study of Women in Gothenburg

STUDY OBJECTIVE

To identify variables available in early Swedish delivery records and their relation to birth outcomes for home and hospital deliveries in Gothenburg at the early part of this century.

DESIGN

A retrospective recovery of original delivery records and social variables in a cross sectional population.

SETTING

Gothenburg, Sweden.

PARTICIPANTS

851 fullterm singleton female births with known gestational age born into five birth cohorts on selected dates (1908, 1914, 1918, 1922 and 1930).

MAIN RESULTS

Delivery site, maternal parity, gestational age, and social group were significant factors influencing birth outcome as birth weight and length. The mean birth weight and length of hospital born infants was consistently lower than for home deliveries across all cohorts. Site of delivery changed significantly during the period of births under study, 1908-1930.

CONCLUSIONS

In this study, which was based on original delivery records from the early part of this century, it was found that delivery site was an important factor influencing birth outcome across five birth cohorts. Utilisation of delivery services changed during the period of study. Thus, to avoid selection bias, the application of delivery records should reflect the birthing practice of the time period in question.

Mode of infant feeding and achieved growth in adolescence: early feeding patterns in relation to growth and body composition in adolescence

OBJECTIVE

Feeding mode in infancy and differences in childhood growth have been studied in several longitudinal studies, but few studies have followed children up to adolescent age. There is evidence that formula-fed infants weigh more and are taller than their breast-fed counterparts, and indications that this difference may sustain.

RESEARCH METHODS AND PROCEDURES

We have studied the relations between length of breast-feeding, growth, and body composition in a group of 781 representatively chosen adolescents. Data on feeding pattern in infancy and on weight and height from birth up to 18 years were collected. We studied the relation between high body mass index (BMI) (defined as < or =85th percentile) in adolescence and length of breast-feeding.

RESULTS

Girls who were not breast-fed or breast-fed for less than 3 months had a significantly higher height curve than girls exclusively breast-fed for more then 3 months. There were tendencies towards higher values of adipose tissue measured by skinfolds in girls breast-fed for 3 months or less. Short duration of exclusive breast-feeding was associated with higher BMI (p<0.04). In a subgroup of 194 adolescents, body composition was measured with dual energy X-ray. Both boys and girls who were exclusively breast-fed for more than 3 months were leaner and showed a trend towards lower skinfold values.

CONCLUSION

These results are important to include in the debate about optimal feeding in infancy. Regarding breast-feeding as a standard, our results imply that formula fed infants may be at risk for overfeeding, which might lead to overweight, even up to adolescent age.

Iron stores in man in relation to diet and iron requirements

OBJECTIVE

To calculate iron stores in man and their rates of changes in relation to iron requirements and dietary iron intake and bioavailability.

METHOD

Newly established relationships between iron absorption from whole diets and serum ferritin (SF) and between SF and iron stores allow calculations of amounts of stored iron under different conditions (diets, losses) at stationary states when absorption equals losses. Rate of growth of stores can also be calculated. All calculations are based on observations and require no model assumptions.

RESULTS

Present calculations of iron stores agree with previously observed phlebotomy values. Differences in intake and bioavailability of dietary iron and in iron requirements had marked effects on amounts of stored iron. A wide range of diets was studied, from a hypothetical high-meat diet typical for early man to diets in developing countries. A new equation is given for the translation of SF into iron stores. Analyses of growth rate of stores under different conditions showed a fast growth from zero iron stores during the first year (reaching about 80% of final amounts) followed by a much slower rate for 2-3 y. A marked inertia was seen in rate of changes in iron stores that was more marked the closer stores were to their stationary states making it difficult to use SF to estimate short term changes in iron absorption in iron replete subjects.

CONCLUSIONS

Realistic Western-type diets with good bioavailability can cover iron requirements in most women and can restitute iron stores during lactation. The high prevalence of iron deficiency in menstruating Western women is thus mainly related to a further low bioavailability of iron in present diets. Present analyses also demonstrated an effective control of iron absorption preventing development of iron overload in otherwise healthy subjects even if the diet is fortified with iron and even if meat intake is high.

Effect of a mild infection on serum ferritin concentration--clinical and epidemiological implications

OBJECTIVES

To study the distribution of serum ferritin concentration in adolescent boys and girls with and without a preceding mild infection.

DESIGN

The prevalence of iron deficiency was studied in two representative samples. The first sample from 1990 comprised 207 boys and 220 girls. The second sample from 1994 included 620 boys and 624 girls. In total 1675 adolescents, 15-16 y old, 827 boys and 844 girls were studied.

RESULTS

A significant shift of serum ferritin concentration towards higher values was observed in those who reported an upper respiratory infection with fever during the preceding month (P<0.001). Significant differences were found between serum ferritin values in healthy, not infected adolescents and serum ferritin values in those with ongoing infection, both in boys and girls in the two materials (P < 0.01), and in those with a mild infection during the preceding three weeks.

CONCLUSIONS

The prevalence of recent infection should be included as information when trying to assess the prevalence of iron deficiency on the basis of serum ferritin measurements and when examining relationships between iron status and composition of the diet. The findings imply that differences in prevalence of iron deficiency between different studies might partly be explained by differences in prevalence of simple respiratory infections. The diagnostic sensitivity of the serum ferritin assay for iron deficiency, using conventional reference limits, decreases for subjects with recent such infections; similarly, there will be a decrease in the diagnostic specificity for haemochromatosis.

Iron balance in menstruating women

OBJECTIVES

To study factors determining iron balance in menstruating women by examining the relationships between total iron requirements, based on menstrual iron losses and basal iron losses, and serum ferritin concentration, transferrin saturation, blood haemoglobin concentration, bone marrow haemosiderin and absorption of iron from a test dose of ferrous sulphate (0.56 mg Fe).

SUBJECTS

The study was made in 203 women all aged 38 years, randomly selected from the census register of Göteborg. The study was originally made in 1968-69. Serum ferritin in frozen sera was first analysed in 1978. Reanalyses, calibrated to the International Standard 80/602, and studies on the effect of storage of sera, were made in 1992. This allowed a complete re-examination of the importance of different determinants of iron balance in women.

RESULTS

With increasing iron requirements there was an increase in iron absorption, and a decrease in serum ferritin concentration and transferrin saturation. Above a certain level of iron requirement there was a rather sudden decrease in haemoglobin concentration and in stainable iron in bone marrow smears, indicating the critical level of iron requirements in these women that could be balanced by an increased iron absorption from the present diet. This level represents the maximal adaptation to maintain iron balance in an iron-replete state that can be achieved with this diet and corresponds to a prevalence of iron deficiency of about 25%.

CONCLUSIONS

The continuous regulation of iron absorption from iron deficiency to iron repletion has a critical balance point determined by the properties of the diet.

Percutaneous transluminal renal angioplasty versus surgical reconstruction of atherosclerotic renal artery stenosis: a prospective randomized study

PURPOSE

The purpose of this prospective randomized study was to compare percutaneous transluminal renal angioplasty (PTRA) and operation as initial therapy with regard to technical results, primary and secondary patency, and effects on blood pressure and renal function in patients with atherosclerotic unilateral renal artery stenosis.

METHODS

Fifty-eight patients who did not have diabetes, who were less than 70 years of age, and who had severe hypertension and significant stenosis were randomized to receive PTRA or operation. Angiography was performed 10 days, 1 year, and 2 years after treatment to verify patency, and blood pressure and renal function were simultaneously evaluated.

RESULTS

Technically, PTRA was successful in 83% and operation in 97% of patients. The primary patency rate after 24 months was 75% in the PTRA group and 96% in the operative group in technically successful cases. The secondary patency rate in the PTRA group was 90% and in the surgical group 97%. To achieve these results four patients in the PTRA group required operation, and one patient in the surgical group required PTRA. Hypertension was cured or improved after additional treatment in 90% of the patients after PTRA and 86% after operation. The corresponding figures for improved or unchanged renal function were 83% and 72%, respectively. After additional treatment, effects on blood pressure and renal function did not differ. Seventeen percent of the patients treated with PTRA required surgical intervention.

CONCLUSIONS

PTRA is recommended as first choice of therapy for atherosclerotic renal artery stenosis causing renovascular hypertension if combined with intensive follow-up and aggressive reintervention.

Percutaneous transluminal renal angioplasty versus surgical reconstruction of atherosclerotic renal artery stenosis: a prospective randomized study

PURPOSE

The purpose of this prospective randomized study was to compare percutaneous transluminal renal angioplasty (PTRA) and operation as initial therapy with regard to technical results, primary and secondary patency, and effects on blood pressure and renal function in patients with atherosclerotic unilateral renal artery stenosis.

METHODS

Fifty-eight patients who did not have diabetes, who were less than 70 years of age, and who had severe hypertension and significant stenosis were randomized to receive PTRA or operation. Angiography was performed 10 days, 1 year, and 2 years after treatment to verify patency, and blood pressure and renal function were simultaneously evaluated.

RESULTS

Technically, PTRA was successful in 83% and operation in 97% of patients. The primary patency rate after 24 months was 75% in the PTRA group and 96% in the operative group in technically successful cases. The secondary patency rate in the PTRA group was 90% and in the surgical group 97%. To achieve these results four patients in the PTRA group required operation, and one patient in the surgical group required PTRA. Hypertension was cured or improved after additional treatment in 90% of the patients after PTRA and 86% after operation. The corresponding figures for improved or unchanged renal function were 83% and 72%, respectively. After additional treatment, effects on blood pressure and renal function did not differ. Seventeen percent of the patients treated with PTRA required surgical intervention.

CONCLUSIONS

PTRA is recommended as first choice of therapy for atherosclerotic renal artery stenosis causing renovascular hypertension if combined with intensive follow-up and aggressive reintervention.

Determination of urinary N-acetyl-beta-glucosaminidase in patients with hypertension and renal artery stenosis

The purpose of the study was to measure the urinary excretion of N-acetyl-beta-glucosaminidase (U-NAG) in patients suspected of having renovascular hypertension and to compare the enzyme excretion before and after active intervention with operation or percutaneous transluminal renal angioplasty (PTRA). Eighty-one patients with severe, therapy-resistant hypertension were examined with regard to renal artery stenosis (RAS). At least one significant renal artery stenosis was found in 61 patients, whilst the remaining 20 patients were classified as having essential hypertension. Enzyme levels were found to be significantly higher in RAS patients as compared with patients with severe hypertension lacking significant renal artery stenosis, 0.66 (0.41-0.91, median value, 1st and 3rd quartiles) versus 0.35 (0.27-0.54); P < 0.01. Both groups of patients had significantly higher U-NAG values than a healthy reference population (0.2, 0.13-0.27; P < 0.01). Forty of the RAS patients were randomized to surgery or PTRA and followed prospectively for 2 years. After either renal vascular surgery or PTRA a significant rise in U-NAG excretion was observed 7-10 days after treatment. Urinary NAG excretion remained elevated during long-term follow-up. It is suggested that U-NAG should be determined in patients with therapy-resistant hypertension with suspicion of renal artery stenosis.

Long-term results after percutaneous transluminal angioplasty of atherosclerotic renal artery stenosis--the importance of intensive follow-up

The aim of this study was to investigate the long-term results of percutaneous transluminal angioplasty of atherosclerotic renal artery stenosis (PTRA) in patients with renovascular hypertension with or without impending renal insufficiency who were followed up intensively with aggressive reintervention. Diagnostic work-up was based on angiography, pressure gradient and renal venous renin measurement. Patients were scheduled for regular follow-up after the PTRA and a deterioration in blood pressure or renal function was an indication for re-evaluation, and reintervention if necessary. Sixty-five patients had 71 renal artery stenoses where PTRA was attempted. It was technically successful in 59 stenoses and two occlusions and failed in ten (14%). At the end of follow-up (median 56 months [2-99]), the primary patency rate was 55%, 27 had restenosed and four were occluded, all but two within 12 months. Seventeen were treated by a further PTRA and eight by surgical reconstruction. At the end of follow-up the secondary patency after all interventions was 90%. One patient died 1 month after PTRA, and at the end of follow-up 21 patients (32%) had died, most of them (80%) from cardiovascular disease. Multivariate analyses showed a significantly reduced survival rate in patients with multiocular atherosclerosis, renal insufficiency, contralateral renal artery stenosis and ischaemic heart disease. At the end of follow-up 90% of the patients were cured or improved with regard to blood pressure. In patients with impending renal insufficiency renal function was improved in 50% and unchanged in 39%. With this strategy 55% of the patients needed only one treatment with PTRA, 25% needed a re-PTRA and 20% had to be operated on. PTRA can be recommended as initial treatment of atherosclerotic renal artery stenosis provided intensive follow-up and aggressive reintervention are performed when indicated.

Antihypertensive and renal effects of enalapril and slow-release verapamil in essential hypertension. A double-blind, randomized study

The renal, metabolic and antihypertensive effects of enalapril (E) and slow-release verapamil (V) were compared in a 2-month double-blind crossover trial in 22 patients with newly discovered essential hypertension. The glomerular filtration rate and renal vascular resistance were unaltered: renal blood flow was slightly decreased by V. Serum Ca2+ increased and Na+ excretion declined after V. Serum lipids, glucose, and erythrocyte electrolytes were unchanged. Blood pressure (BP) was lower with E after half the maximum dosage compared with V, but similar BP reductions were obtained after 2 months with the maximum dosage.

Verapamil-induced vasodilator response is enhanced in essential hypertension

Forearm blood flow response to the calcium channel inhibitor verapamil, 1 75 micrograms/100 ml tissue, as measured by venous occlusion plethysmography, was found to be significantly greater in 11 patients with essential hypertension as compared to 11 age-matched normotensive subjects whereas there was no significant difference in increase in forearm blood flow between both groups to non-specific vasodilatation with sodium nitroprusside (1.2 micrograms/100 ml tissue). The increase in forearm blood flow to verapamil correlated positively with basal plasma epinephrine concentration in hypertensives. These findings support the concept of an increased dependency of arteriolar tone on calcium influx in patients with essential hypertension, an abnormally related to the activity of the sympathetic nervous system.

Antihypertensive and renal effects of captopril in relation to renin activity and bradykinin-induced vasodilation

The effect of captopril on blood pressure and renal hemodynamics in relation to plasma renin activity (PRA) was assessed together with the vasodilator responses to brachial artery infusions of bradykinin (BK) and sodium nitroprusside (NP) before and after 4 wk of therapy with doses of up to 450 mg/day in patients with essential hypertension. The average blood pressure reduction of captopril was from 174.4/110.6 to 155.3/96.6 mm Hg (n = 12, P less than 0.001) without increases in heart rate or body weight. It was effective in the eight patients with normal renin, but showed little effect in the four with a low renin. There was a correlation between the changes in blood pressure after captopril and the pretreatment PRA (r = -0.82, P less than 0.01 for mean pressure). Brachial artery infusions of BK and NP induced dose-dependent rises in forearm blood flow (FBF), but this was not related to the captopril blood pressure-lowering effect. Repeat measurements during captopril therapy showed a shift to the left of the BK/FBF, but not of the NP/FBF, dose-response curve, indicating effective vascular kininase II inhibition. Captopril decreased renal vascular resistance. Our data are compatible with the view that captopril's antihypertensive action mainly involves blockade of the renin-angiotensin-aldosterone system and not cumulation of BK. The favorable effects on renal hemodynamics and the lack of tachycardia and volume retention after captopril make it a valuable drug for the treatment of hypertension.

Elevated adrenaline and increased alpha-adrenoceptor-mediated vasoconstriction in essential hypertension

In patients with essential hypertension, plasma adrenaline, regardless of age, was consistently higher than in normotensive controls; adrenaline correlated with heart rate and the vasodilator response in the forearm circulation produced by postjunctional alpha 1-adrenoceptor blockade with prazosin. This dilator response to prazosin was greater in hypertensive patients. Together, this suggests elevated sympathetic activity and enforced vasoconstriction via postjunctional alpha 1-adrenoceptors in essential hypertension. beta-Adrenoceptor-mediated cardiovascular responses decrease with age and even more with high blood pressure, which contributes to unopposed alpha-adrenoceptor-mediated vasoconstriction. This could explain the transition from an early high cardiac output into a later high peripheral resistance form of hypertension.

Decrease in alpha-adrenoceptor-mediated vasoconstriction parallels the antihypertensive response to propranolol in patients with normal renin essential hypertension

1. α1-Adrenoceptor-mediated vasoconstriction was studied before and during propranolol therapy in eight normal renin essential hypertensive patients; four were known ‘responders’ and four, age-matched ‘non-responders’ to previous β-receptor blocker monotherapy. Plasma renin activity, plasma adrenaline and noradrenaline concentrations as well as forearm blood flow were measured before and during regional postjunctional α1-adrenoceptor blockade with prazosin. All measurements were done on placebo and again after 6 weeks’ propranolol monotherapy (320 mg/day).

2. Propranolol reduced heart rate and plasma renin activity to the same extent in ‘responders’ and ‘non-responders’. Resting plasma adrenaline concentrations tended to be higher in ‘responders’ before propranolol; they remained unchanged in both groups on propranolol. Plasma noradrenaline concentrations were similar in both groups before and on propranolol.

3. Before propranolol forearm flow was not different in ‘responders’ and ‘non-responders’. Non-specific vasodilatation with sodium nitroprusside produced a similar increase in forearm flow before and after propranolol in both groups.

4. Prazosin-induced increments in forearm flow tended to be higher in ‘responders’ before propranolol. After propranolol the vasodilator effect of prazosin was attenuated in ‘responders’ but it remained unchanged in ‘non-responders’ (P &lt; 0.01).

5. In patients with normal renin essential hypertension the antihypertensive response to propranolol monotherapy is paralleled by a decrease in postjunctional α1-adrenoceptor-mediated vasoconstriction.

Elevated plasma adrenaline reflects sympathetic overactivity and enhanced alpha-adrenoceptor-mediated vasoconstriction in essential hypertension

1. Stressful sympathetic stimulation (cold pressor test) was applied to 18 patients with essential hypertension and 15 normotensive subjects. Intra-arterial blood pressure, heart rate, plasma adrenaline and noradrenaline concentrations as well as forearm blood flow were measured before and during the cold pressor test; tests were repeated after regional postsynaptic α1-adrenoceptor blockade with prazosin.

2. Under basal conditions mean blood pressure (P &lt; 0.001), heart rate (P &lt; 0.01), forearm blood flow (P &lt; 0.001) as well as adrenaline concentration (P &lt; 0.01), but not noradrenaline, was higher in patients with essential hypertension.

3. During the cold pressor test, mean blood pressure, heart rate, plasma adrenaline and noradrenaline concentrations increased and forearm flow decreased (all P &lt; 0.001).

4. Stress-stimulated plasma adrenaline was higher in essential hypertensive patients than in normotensive subjects (P &lt; 0.01). In the former the stress-induced increase in plasma adrenaline correlated with the increase in mean blood pressure (r = 0.514; P &lt; 0.05).

5. Prazosin increased forearm blood flow more in essential hypertension (P &lt; 0.001). This increase correlated with the resting plasma adrenaline in the hypertensive (r = 0.710; P &lt; 0.001), but not in normotensive, subjects.

6. When the cold pressor test was repeated during postsynaptic α1-adrenoceptor blockade forearm blood flow did not decrease; instead it increased further in both groups (P &lt; 0.05).

7. Thus in essential hypertension elevated plasma adrenaline concentration reflects sympathetic overactivity as also expressed by enhanced α-adrenoceptor-mediated vasoconstriction.

Kinins in relation to renin activity in renal and inferior caval veins in normal individuals and patients with primary aldosteronism

Blood kinin concentration and plasma renin activity (PRA) were determined in the renal veins and in the inferior caval vein (ICV) below the level of the renal veins in 9 normal individuals (5 men and 4 women) and 7 patients with primary aldosteronism (3 men and 4 women). PRA in the renal veins and ICV was significantly lower and plasma aldosterone concentration in ICV significantly higher in the patients as compared to the normals. Kinin concentration in the renal veins and ICV did not differ significantly between the patients and the normals (0.31 +/- 0.04 (mean +/- SEM) vs 0.45 +/- 0.03 and 0.27 +/- 0.05 vs 0.45 +/- 0.06 microgram/l, respectively). In the normal individuals kinin concentration and PRA were inversely related in the left renal vein (r = -0.80; P less than 0.02), whereas this relation did not reach statistical significance in the right renal vein (r = -0.60; P less than 0.10). Kinin concentration in both renal veins was positively correlated to kinin concentration in ICV (r = 0.73; P less than 0.05 and r = 0.83; P less than 0.02 for the right and left renal vein, respectively). These results indicate that intrarenal kinin formation and renin release are inversely related in normal subjects. Furthermore, they suggest that one and the same enzyme, possibly renal kallikrein, may be implicated in the kinin formation in the systemic as well as in the renal circulation. Intrarenal kinin formation seems not to be increased in primary aldosteronism.