Atlantic halibut growth hormone: structure and plasma levels of sexually mature males and females during photoperiod-regulated annual cycles

The main objectives of this study were to obtain the amino acid sequence of Atlantic halibut (Hippoglossus hippoglossus) growth hormone (hhGH) and compare it with other teleost species, to establish a radioimmunoassay to assess plasma hhGH levels and thus to gain information about possible biological functions and regulation by photoperiod. The hhGH gene was cloned and its amino acid sequence deduced from the cDNA. The mature hhGH protein consists of 186 amino acids. Comparison with other flatfish species as well as a species from a different order, the pufferfish, reveals that the sequence similarities of the mature hhGH with that of the barfin flounder, the Japanese flounder, the sole and the pufferfish are 99.5, 81.7, 74.2, and 65.2%, respectively. The sequence similarities appear to correctly reflect the gross phylogenetic relationships among these teleost species. A specific GH-RIA was developed for measurements of Atlantic halibut GH levels. Assessment of plasma GH levels in adult halibut revealed large gender differences, with GH levels frequently being an order of magnitude higher in males than females. The mean (+/-SEM) plasma GH for males kept on normal annual photoperiod were 25.2+/-6.11 ngml(-1) and for females were 5.14+/-1.94 ngml(-1). It appears likely that plasma growth hormone levels in Atlantic halibut can be inversely correlated to growth and metabolism. Shifting of the annual photoperiod cycles demonstrated that photoperiod in not a regulator of plasma GH levels in the Atlantic halibut, but further research is needed to assess whether GH plays a role in the reproduction of this marine teleost species.     

Declining coronary heart disease mortality in Iceland: contribution by incidence,recurrence and case fatality rate

OBJECTIVE: To analyse to what extent the recent decline in coronary heart disease mortality in Iceland is due to changes in incidence, recurrence and case fatality rates. DESIGN: A countrywide registration of myocardial infarction (MI) in people aged 25-74 was performed in Iceland during 1981-1999 according to the MONICA protocol. Possible cases were found by review of all hospital discharge records, autopsy records and death certificates. RESULTS: MI death rate declined by 63% in males and 51% in females, most in the youngest age groups in men (86%) and least in the oldest (49%). In women there was not a significant difference in age groups. Overall the age-adjusted reduction in MI death rate was 55.4% in both sexes combined; of this 23.1% was due to incidence reduction, 22.8% to recurrence reduction and 11.6% to case fatality reduction. In the youngest age groups the decline in incidence contributed most to the decline in MI death rate (62% in men and 71% in women), but thereafter the decline in case fatality in men. In the older age groups decline in recurrence rate has greater weight. CONCLUSION: The recent decline in MI mortality under the age of 75 years in Iceland is due to reduction in incidence and recurrence rate by about 40% each and to reduction in case fatality by 20%.     

Mandibular third molar removal: risk indicators for extended operation time, postoperative pain, and complications

OBJECTIVES: The aim of this study was to identify risk indicators for extended operation time and postoperative complications after removal of mandibular third molars. STUDY DESIGN: There were 388 molars included in the study. The teeth were removed using the buccal approach under local anesthesia. Four hours postoperatively the patient recorded his or her pain perception on a visual analogue scale (VAS). After surgery a surgeon recorded parameters regarding the tooth and if the mandibular nerve had been visible during the operation. One week postoperatively the postoperative pain and complications were recorded. Logistic regression models were made to identify risk indicators for extended operation time, postoperative pain, and complications. RESULTS: Females were at higher risk for postoperative pain and dry socket than males. Older patients were at higher risk for extended operation time than younger patients. Radiographically fully impacted molars increased the risk of postoperative general infection. If the nerve was visible during surgery there was a higher risk of a high VAS score, postoperative pain, and general infection than if the nerve had not been visible. CONCLUSION: Several indicators were found to increase the risk of postoperative complications, but a visible alveolar inferior nerve during the operation was repeatedly found to be the highest single risk indicator.     

Differential regulation of hippocampal progenitor proliferation by opioid receptor antagonists in running and non-running spontaneously hypertensive rats

Voluntary running in mice and forced treadmill running in rats have been shown to increase the amount of proliferating cells in the hippocampus. Little is known as yet about the mechanisms involved in these processes. It is well known that the endogenous opioid system is affected during running and other forms of physical exercise. In this study, we evaluated the involvement of the endogenous opioids in the regulation of hippocampal proliferation in non-running and voluntary running rats. Nine days of wheel running was compared with non-running in spontaneously hypertensive rats (SHR), a rat strain known to run voluntarily. On the last 2 days of the experimental period all rats received two daily injections of the opioid receptor antagonists naltrexone or naltrindole together with injections of bromodeoxyuridine to label dividing cells. Brain sections from the running rats showed approximately a five-fold increase in newly generated cells in the hippocampus, and this increase was partly reduced by naltrexone but not by naltrindole. By contrast, both naltrexone and naltrindole increased hippocampal proliferation in non-running rats. In non-running rats the administration of naltrexone decreased corticosterone levels and adrenal gland weights, whereas no significant effects on these parameters could be detected for naltrindole. However, adrenal gland weights were increased in naltrexone- but not in naltrindole-administered running rats. In addition, in voluntary running rats there was a three-fold increase in the hippocampal levels of Met-enkephalin-Arg-Phe compared with non-runners, indicating an increase in opioid activity in the hippocampus during running. These data suggest an involvement of endogenous opioids in the regulation of hippocampal proliferation in non-running rats, probably through hypothalamic-pituitary-adrenal axis modulation. During voluntary running in SHR naltrexone altered hippocampal proliferation via as yet unknown mechanisms.     

Persistence of the effect of birth size on dysglycaemia and type 2 diabetes in old age: AGES-Reykjavik Study

We studied the effect of birth size on glucose and insulin metabolism among old non-diabetic individuals. We also explored the combined effect of birth size and midlife body mass index (BMI) on type 2 diabetes in old age. Our study comprised 1,682 Icelanders whose birth records included anthropometrical data. The same individuals had participated in the prospective population-based Reykjavik Study, where BMI was assessed at a mean age of 47 years, and in the AGES-Reykjavik Study during 2002 to 2006, where fasting glucose, insulin and HbA_1c were measured and homeostasis model assessment for the degree of insulin resistance (HOMA-IR) calculated at a mean age of 75.5 years. Type 2 diabetes was determined as having a history of diabetes, using glucose-modifying medication or fasting glucose of >7.0 mmol/l. Of the participants, 249 had prevalent type 2 diabetes in old age. Lower birth weight and body length were associated with higher fasting glucose, insulin, HOMA-IR and HbA_1c among old non-diabetic individuals. Higher birth weight and ponderal index at birth decreased the risk for type 2 diabetes in old age, odds ratio (OR), 0.61 [95 % confidence interval (CI), 0.48–0.79] and 0.96 (95 % CI, 0.92–1.00), respectively. Compared with those with high birth weight and low BMI in midlife, the odds of diabetes was almost five-fold for individuals with low birth weight and high BMI (OR, 4.93; 95 % CI, 2.14–11.37). Excessive weight gain in adulthood might be particularly detrimental to the health of old individuals with low birth weight.     

Thresholds for minimum data set quality indicators developed and applied in icelandic nursing homes

A modified Delphi method was used to determine thresholds for Minimum Data Set quality indicators for Icelandic nursing homes. The thresholds were then applied to quality outcomes in Icelandic nursing homes for the year 2009. The thresholds indicate areas of good or poor care and can be used for planning services. Icelandic nursing homes seem to be doing best in incontinence and nutritional care. However, improvement is needed in care practices for depression, medication, and activity.     

DHEA and DHEA-S response to acute psychosocial stress in healthy men and women

This study investigates the effect of acute psychosocial stress on serum concentrations of DHEA and DHEA-S in healthy men and women. Twenty men and 19 women (age 30-50 years) underwent Trier Social Stress Test (TSST). Physiological measurements were performed before, directly after the stress test and after 30 mins of recovery. In both men and women, significantly elevated DHEA and DHEA-S levels were observed in response to the stressor. There was a large inter-individual variation in the magnitude of the response, especially for DHEA but no statistical difference between men and women. Magnitude of the change in the levels of DHEA was found to be positively associated with the magnitude of the changes in ACTH, cortisol and heart rate. Furthermore, the results of this study suggest that the capacity to secrete DHEA and DHEA-S during acute psychosocial stress declines with age.     

Concerns Regarding Hair Cortisol as a Biomarker of Chronic Stress in Exercise and Sport Science

Hair cortisol has the potential to fill the methodological void of long-term cortisol assessment while becoming a widely accepted measure in biopsychology. This review critically examines the applicability and relevance of hair cortisol measurement specifically within the field of exercise and sport science. Current measures of the HPA axis only cover a brief time period, whereas hair cortisol is a unique, non-invasive means to capture long- term cortisol secretion. Studies have shown that individuals who have elevated cortisol secretion (e.g. due to diseases associated with a disturbed activation of the HPA axis or exposure to stressful life events) reveal increased hair cortisol. By contrast, only weak correlations exist between hair cortisol and perceived stress, and the direction of the relationship between hair cortisol levels and mental disorders is unclear. Acute exercise, however, results in increased levels of cortisol that eventually is reflected in higher levels of cortisol in hair samples and studies have shown that exercise intensity is related to hair cortisol level. Thus, elevated hair cortisol levels found among regular exercisers are not necessarily pathological. Thus, one should practice caution when associating athletes’ elevated hair cortisol with poor mental health or disease. Hair cortisol analysis can contribute to a more complete understanding of how long-term cortisol elevation mediates stress-related effects on the health and performance of recreational exercisers and elite athletes. Nevertheless, it is crucial for exercise and sport scientists to consider whether their research questions can be adequately addressed, given that regular intense exercise results in substantially augmented hair cortisol levels.

Key points

• Hair cortisol is a unique, non-invasive and painless means to capture long-term cortisol secretion.
• Individuals expected to have elevated cortisol secretion (e.g. due to trauma) have increased hair cortisol.
• Preliminary evidence shows that exercisers have higher hair cortisol levels as well.
• Hair cortisol analysis can contribute to a more complete understanding of how long-term cortisol secretion mediates stress-related effects on health and performance.
• There is a great dearth of knowledge about the relationship between sport, exercise and hair cortisol.

Key words: Exercise, hair cortisol, physical activity, review, stress     

Isolation of Atlantic halibut pituitary hormones by continuous-elution electrophoresis followed by fingerprint identification, and assessment of growth hormone content during larval development

Continuous-elution electrophoresis (CEE) has been applied to separate putative hormones from adult Atlantic halibut pituitaries. Soluble proteins were separated by size and charge on Model 491 Prep Cell (Bio-Rad), where the homogenate runs through a cylindrical gel, and protein fractions are collected as they elute from the matrix. Protein fractions were assessed by SDS-PAGE and found to contain purified proteins of molecular size from 10 to 33 kDa. Fractions containing proteins with molecular weights of approximately 21, 24, 28 and 32 kDa, were identified as putative growth hormone (GH), prolactin, somatolactin and gonadotropins, respectively. These were analyzed further by mass spectrometry and identified with peptide mass protein fingerprinting. The CEE technique was used successfully for purification of halibut GH with a 5% yield, and appears generally well suited to purify species-specific proteins often needed for research in comparative endocrinology, including immunoassay work. Thus, the GH obtained was subsequently used as standards and iodination label in a homologous radioimmunoassay, applied to analyze GH content through larval development in normally and abnormally metamorphosing larvae. As GH is mainly found in the pituitary, GH contents were analyzed in tissue extracts from the heads only. The pituitary GH content increases proportionally to increased larval weight from first feeding to metamorphic climax. No difference in relative GH content was found between normal and abnormal larvae and it still remains to be established if GH has a direct role in metamorphosis.