The association of access to green space with low mental distress and general health in older adults: a cross-sectional study.

BACKGROUND: Access to green space is considered beneficial to mental and physical health, though the causal pathways are not completely clear. Accordingly, the objective of this study was to examine how access to green space was associated with low mental distress and general health among older adults. METHODS: The data in our study stems from a survey from three Norwegian counties in 2015-16, n = 2937. The main exposure variable was self-reported access to green space, and the outcome variables were self-reported mental distress and general health. Logistic regression adjusted for sex, age, education, physical activity, functional disability, access to cultural/sports facilities and economic security was performed to assess the association between the exposure variable and the outcome variables. RESULTS: Access to green space was associated with both higher odds of low mental distress (Odds Ratio = 3.85**, 95% CI 2.04-6.02) and good general health (OR = 8.20**, 95%CI 5.88-11.49) compared to no access. In models adjusted for sex, age, and education, the ORs were only slightly changed (OR = 4.03**, 95%CI 2.52-6.45) and (OR = 7.91**, 95%CI 5.63-11.13). However, adjusting for general health with low mental distress as outcome, the association was no longer statistically significant; (OR = 1.28 95%CI 0.74-2.21). Adjusting for low mental distress with general health as outcome, the association remained statistically significant; (OR = 3.43** 95%CI 2.34-5.03). CONCLUSIONS: Our findings suggest that the association between access to green space and mental health may be mediated by general health. This implies that studies of associations between access to green space and mental health must take general health into consideration.

Mortality in Norway and Sweden during the COVID-19 pandemic 2020-22: A comparative study.

BACKGROUND: Norway and Sweden picked two different ways to mitigate the dissemination of the SARS-CoV-2 virus. Norway introduced the strictest lockdown in Europe with strict border controls and intense virus tracking of all local outbreaks while Sweden did not. That resulted in 477 COVID-19 deaths (Norway) and 9737 (Sweden) in 2020, respectively. METHODS: Weekly number of COVID-19 related deaths and total deaths for 2020-22 were collected as well as weekly number of deaths for 2015-19 which were used as controls when calculating excess mortality. During the first 12-18 months with high rate of virus transmission in the society, excess mortality rates were used as substitute for COVID-19 deaths. When excess mortality rates later turned negative because of mortality displacement, COVID-19 deaths adjusted for bias due to overreporting were used. RESULTS: There were 17521 COVID-19 deaths in Sweden and 4272 in Norway in the study period. The rate ratio (RR) of COVID-19 related deaths in Sweden vs. Norway to the end of week 43, 2022, was 2.11 (95% CI 2.05-2.19). RR of COVID-19 related deaths vs. excess number of deaths were 2.5 (Sweden) and 1.3 (Norway), respectively. RR of COVID-19 deaths in Sweden vs. Norway after adjusting for mortality displacement and lockdown, was 1.35 (95% CI 1.31-1.39), corresponding to saving 2025 life in Norway. If including all deaths in 2022, RR= 1.28 (95% CI 1.24-1.31). CONCLUSIONS: Both COVID-19 related mortality and excess mortality rates are biased estimates. When adjusting for bias, mortality differences declined over time to about 30% higher mortality in Sweden after 30 months with pandemics.

Mental distress among young adults - gender differences in the role of social support.

BACKGROUND: The aim of the present study was to examine to what extent observed gender differences in mental health are associated with the protective factors social support, sense of coherence and participation in regular physical activity and more generally, engagement in organized or unorganized activity with other people. METHODS: This study was based upon a cross-sectional regional health survey in Norway, conducted during the winter of 2015-2016, in three southern counties; Aust-Agder, Vest-Agder and Vestfold. The study focused on young adults, comparing three age groups; 18-24 years old (n = 624), 25-31 (n = 582), and 32-38 years old (n = 795). RESULTS: Sense of coherence was strongly associated with low mental distress in all age groups and for both genders, while the association between low social support and mental distress was significant for young women only. Regular physical activity was not positively associated with low mental distress when sense of coherence and social support were included in the analysis. CONCLUSION: Social support appears to have a stronger role as a protective factor for mental distress among young women, compared to young men and older persons. This has implications for health promoting activities that target young women. Sense of coherence showed a strong association with low mental distress scores for all ages studied.

OXR1A, a Coactivator of PRMT5 Regulating Histone Arginine Methylation.

Oxidation resistance gene 1 (OXR1) protects cells against oxidative stress. We find that male mice with brain-specific isoform A knockout (Oxr1A-/-) develop fatty liver. RNA sequencing of male Oxr1A-/- liver indicates decreased growth hormone (GH) signaling, which is known to affect liver metabolism. Indeed, Gh expression is reduced in male mice Oxr1A-/- pituitary gland and in rat Oxr1A-/- pituitary adenoma cell-line GH3. Oxr1A-/- male mice show reduced fasting-blood GH levels. Pull-down and proximity ligation assays reveal that OXR1A is associated with arginine methyl transferase PRMT5. OXR1A-depleted GH3 cells show reduced symmetrical dimethylation of histone H3 arginine 2 (H3R2me2s), a product of PRMT5 catalyzed methylation, and chromatin immunoprecipitation (ChIP) of H3R2me2s shows reduced Gh promoter enrichment. Finally, we demonstrate with purified proteins that OXR1A stimulates PRMT5/MEP50-catalyzed H3R2me2s. Our data suggest that OXR1A is a coactivator of PRMT5, regulating histone arginine methylation and thereby GH production within the pituitary gland.

Perceived discrimination, health and mental health among immigrants in Norway: the role of moderating factors.

BACKGROUND: Ethnic discrimination is a relatively common experience among immigrants and ethnic minorities. The experience of discrimination can have detrimental effects on an individual's health and well-being. This study investigated the association between perceived discrimination and general health and mental health among immigrants in Norway, in order to identify potential protective factors. METHODS: Using data from the Living Conditions Survey among Immigrants 2016, our sample consisted of 4294 participants aged 16-66 years from 12 different countries. Participants were asked about a variety of themes including health and mental health, perceived discrimination, sense of belonging and language proficiency. RESULTS: Around 27% of participants reported perceived discrimination. While perceived discrimination was not associated with general health, logistic regression analyses indicated that it was associated with 1.86 higher odds of mental health problems, even after adjusting for sociodemographic and psychosocial variables. Further, interaction analyses suggested that sense of belonging and trust in others moderated the relationship. Those with higher levels of trust did not have increased odds of mental health problems when experiencing discrimination, while those with low levels of trust did. In line with rejection sensitivity theory, the association between perceived discrimination and mental health was stronger for participants who had a strong sense of belonging to their own country of origin but not to Norway compared with those who had a sense of belonging to both. CONCLUSIONS: Improved integration strategies could potentially improve the mental health of immigrants as well as increase the acceptability of diversity, which in turn, could reduce discrimination towards immigrants. Limitations and suggestions for further research are discussed.

Glycosylated Chromogranin A in Heart Failure: Implications for Processing and Cardiomyocyte Calcium Homeostasis.

BACKGROUND: Chromogranin A (CgA) levels have previously been found to predict mortality in heart failure (HF), but currently no information is available regarding CgA processing in HF and whether the CgA fragment catestatin (CST) may directly influence cardiomyocyte function. METHODS AND RESULTS: CgA processing was characterized in postinfarction HF mice and in patients with acute HF, and the functional role of CST was explored in experimental models. Myocardial biopsies from HF, but not sham-operated mice, demonstrated high molecular weight CgA bands. Deglycosylation treatment attenuated high molecular weight bands, induced a mobility shift, and increased shorter CgA fragments. Adjusting for established risk indices and biomarkers, circulating CgA levels were found to be associated with mortality in patients with acute HF, but not in patients with acute exacerbation of chronic obstructive pulmonary disease. Low CgA-to-CST conversion was also associated with increased mortality in acute HF, thus, supporting functional relevance of impaired CgA processing in cardiovascular disease. CST was identified as a direct inhibitor of CaMKIIδ (Ca2+/calmodulin-dependent protein kinase IIδ) activity, and CST reduced CaMKIIδ-dependent phosphorylation of phospholamban and the ryanodine receptor 2. In line with CaMKIIδ inhibition, CST reduced Ca2+ spark and wave frequency, reduced Ca2+ spark dimensions, increased sarcoplasmic reticulum Ca2+ content, and augmented the magnitude and kinetics of cardiomyocyte Ca2+ transients and contractions. CONCLUSIONS: CgA-to-CST conversion in HF is impaired because of hyperglycosylation, which is associated with clinical outcomes in acute HF. The mechanism for increased mortality may be dysregulated cardiomyocyte Ca2+ handling because of reduced CaMKIIδ inhibition.

An in vitro Study of Protein Adsorption to Biocompatible Coatings.

The motivation for these experiments was to investigate the amount and type of protein adsorption on surfaces that can be used as protective coatings on membrane based in vivo devices. Adsorption of proteins to a selection of biocompatible coatings (titanium oxide, diamond-like carbon, parylene C) and typical construction materials for Micro Electro Mechanical Systems (silicon, silicon nitride), were investigated during in vitro tests. The samples were incubated in human liver extract and bovine serum albumin (BSA) for up to 12 hours. The amount of protein adsorption was found to be low for all surfaces. Measurements of bound Iodine-125 labeled BSA, showed a protein adsorption of up to 0.2 µg BSA/cm2. The specific proteins adsorbed to the surfaces after incubation in human liver extract were identified using mass spectrometry. Most of the identified adsorbed proteins were intracellular, but plasma proteins like Immunoglobulin (Ig) and serum albumin as well as hemoglobin were also identified.

Secretoneurin is a novel prognostic cardiovascular biomarker associated with cardiomyocyte calcium handling.

BACKGROUND: Secretoneurin (SN) levels are increased in patients with heart failure (HF), but whether SN provides prognostic information and influences cardiomyocyte function is unknown. OBJECTIVES: This study sought to evaluate the merit of SN as a cardiovascular biomarker and assess effects of SN on cardiomyocyte Ca(2+) handling. METHODS: We assessed the association between circulating SN levels and mortality in 2 patient cohorts and the functional properties of SN in experimental models. RESULTS: In 143 patients hospitalized for acute HF, SN levels were closely associated with mortality (n = 66) during follow-up (median 776 days; hazard ratio [lnSN]: 4.63; 95% confidence interval: 1.93 to 11.11; p = 0.001 in multivariate analysis). SN reclassified patients to their correct risk strata on top of other predictors of mortality. In 155 patients with ventricular arrhythmia-induced cardiac arrest, SN levels were also associated with short-term mortality (n = 51; hazard ratio [lnSN]: 3.33; 95% confidence interval: 1.83 to 6.05; p < 0.001 in multivariate analysis). Perfusing hearts with SN yielded markedly increased myocardial levels and SN internalized into cardiomyocytes by endocytosis. Intracellularly, SN reduced Ca(2+)/calmodulin (CaM)-dependent protein kinase II δ (CaMKIIδ) activity via direct SN-CaM and SN-CaMKII binding and attenuated CaMKIIδ-dependent phosphorylation of the ryanodine receptor. SN also reduced sarcoplasmic reticulum Ca(2+) leak, augmented sarcoplasmic reticulum Ca(2+) content, increased the magnitude and kinetics of cardiomyocyte Ca(2+) transients and contractions, and attenuated Ca(2+) sparks and waves in HF cardiomyocytes. CONCLUSIONS: SN provided incremental prognostic information to established risk indices in acute HF and ventricular arrhythmia-induced cardiac arrest.

Transforming EQ-5D utilities for use in cost­value analysis of health programs.

In a number of jurisdictions there is increasing interest in incorporating concerns for fairness in models for economic evaluation of health interventions. Cost­value analysis is a name for evaluations with such a broader aim. The most widely held concern for fairness is a concern for the worse off, i.e. the idea that severity of illness should count in determining priorities. In economic evaluations of improvements in health-related quality of life this concern may be taken into account by replacing conventional health state utilities with societal values for health states that are characterised by strong upper end compression and decreasing marginal value of utility gains. We review evidence on the strength of concerns for the worse off--measured at the cardinal level--in 15 articles published in peer-reviewed journals in the time period 1978­2010, with reports from altogether 20 individual studies in nine different countries. We report 116 individual observations of paired comparisons of utility improvements with different start levels. Concerns for severity show up quite strongly across countries, sample types and question framings. By means of regression analyses we fit a societal value function to the data that has the property of decreasing marginal value of utility gains. Using the central tendency in the data we present two plausible transformations of EQ-5D utilities into societal values that reflect concerns for the worse off.

Human OXR1 maintains mitochondrial DNA integrity and counteracts hydrogen peroxide-induced oxidative stress by regulating antioxidant pathways involving p21.

The oxidation resistance gene 1 (OXR1) prevents oxidative stress-induced cell death by an unknown pathway. Here, depletion of human OXR1 (hOXR1) sensitized several human cell lines to hydrogen peroxide-induced oxidative stress, reduced mtDNA integrity, and increased apoptosis. In contrast, depletion of hOXR1 in cells lacking mtDNA showed no significant change in ROS or viability, suggesting that OXR1 prevents intracellular hydrogen peroxide-induced increase in oxidative stress levels to avoid a vicious cycle of increased oxidative mtDNA damage and ROS formation. Furthermore, expression of p21 and the antioxidant genes GPX2 and HO-1 was reduced in hOXR1-depleted cells. In sum, these data reveal that human OXR1 upregulates the expression of antioxidant genes via the p21 signaling pathway to suppress hydrogen peroxide-induced oxidative stress and maintain mtDNA integrity.

Concerns for severity in priority setting in health care: a review of trade-off data in preference studies and implications for societal willingness to pay for a QALY.

OBJECTIVE: In a wide range of health care jurisdictions, to give priority to the severely ill over the less severely ill is important in decisions about resource allocation across patient groups. We summarise data on concerns for severity measured at a cardinal level in preference studies in various countries and show how the data may provide guidance for determining severity graded willingness to pay for a QALY. METHODS: We review evidence in 15 articles published in peer reviewed journals in the time period 1978-2010, with reports from altogether 20 individual studies in 9 different countries. The studies all focus on the quality of life dimension of severity, i.e. utility losses on the 0-1 scale used in QALY-calculations. We report 116 individual observations of paired comparisons of utility improvements with different start levels. We argue that the strength of concerns observed on the quality of life dimension may be assumed to apply also to losses in length of life and thus to severity in terms of proportional shortfall of QALYs. By means of regression analyses we estimate a severity gradient in each study that suggests the span in societal willingness to pay for a QALY to people at high and low levels of severity respectively. RESULTS: Concerns for severity show up quite strongly across countries, sample types and question framings, although the size of the severity gradient varies very much. Interested policy makers may hopefully find the central tendency in the results to be useful as an input to determining severity dependent willingness to pay for a QALY.

Observed trends in mental health: a strategy to adjust for nonresponse bias and demographic changes in survey data.

AIMS: To examine whether observed changes in self-reported psychological distress symptoms reflect true changes in psychological distress in the population, or more specifically, to present statistical methods to check for nonresponse bias and demographic changes. METHODS: Lack of representativity, nonresponse bias and demographic changes were controlled for by weighing of data (sample-balancing or raking). RESULTS: Controlling for age, gender and education, or holding the demographic structure constant over time, slightly weakened the decrease in psychological distress from 1998 to 2002, and left the changes in psychological distress from 2002 to 2008 almost unchanged. When the level of psychological distress was held constant across years in every subgroup defined by age, gender and education, in order to isolate the effects of changes in demography, the distress scores showed only minor variation across data collection occasions from 1998 to 2008. CONCLUSIONS: The observed modest decrease in psychological distress from 1998 to 2002 may partly be explained by selection and demographic changes, while this is not the case with the more pronounced changes from 2002 to 2008.

A randomized controlled trial of a senior centre group programme for increasing social support and preventing depression in elderly people living at home in Norway.

BACKGROUND: Late-life depression is a common condition and a challenging public health problem. A lack of social support is strongly associated with psychological distress. Senior centres seem to be suitable arenas for community-based health promotion interventions, although few studies have addressed this subject. The objectives were to examine the effect of a preventive senior centre group programme consisting of weekly meetings, on social support, depression and quality of life. METHODS: A questionnaire was sent to a random sample of 4,000 persons over 65 in Oslo, and a total of 2,387 completed questionnaires were obtained. These subjects served as a basis for recruitment of participants for a trial, with scores on HSCL-10 being used as a main inclusion criterion. A total of 138 persons were randomized into an intervention group (N = 77) and control group (N = 61). Final analyses included 92 persons. Social support (OSS-3), depression (BDI), life satisfaction and health were measured in interviews at baseline and after 12 months (at the end of the intervention programme). Perceptions of benefits from the intervention were also measured. Mean scores, SD, SE and CI were used to describe the changes in outcomes. Effect sizes were calculated based on the original scales and as Cohen's d. Paired sample tests and ANOVA were used to test group differences. RESULTS: There was an increase in social support in both groups, but greatest in the intervention group. The level of depression increased for both groups, but more so in the control than the intervention group. There was a decrease in life satisfaction, although the decrease was largest among controls. There were almost no differences in reported health between groups. However, effect sizes were small and differences were not statistically significant. In contrast, most of the participants said the intervention meant much to them and led to increased use of the centre. CONCLUSIONS: In all probability, the intervention failed to meet optimistic targets, but possibly met quite modest ones. Since intention-to-treat analysis was not possible, we do not know the effect on the intervention group as a whole. A further evaluation of these programmes is necessary to expand the group programme. For the depressed, more specialized programmes to cope with depression may be a more appropriate intervention. TRIAL REGISTRATION: DRKS00003120 on DRKS.

Pelvic girdle pain in pregnancy: the impact of parity.

OBJECTIVE: The purpose of this study was to estimate the association of parity with pelvic girdle syndrome (PGS; pain in anterior and bilateral posterior pelvis). STUDY DESIGN: We included 75,939 pregnant women in the Norwegian Mother and Child Cohort Study. Data were obtained by self-administered questionnaires. RESULTS: By pregnancy week 30, 15% of the women had developed PGS. Among first-time mothers, 11% of the women reported PGS, compared with 18% of the women with 1 previous delivery and 21% of women with 2 previous deliveries. The odds ratios for PGS of having had 1 or 2 previous deliveries were 1.9 (95% confidence interval [CI], 1.9-2.0) and 2.4 (95% CI, 2.3-2.6), respectively, after adjustment for other study factors. For PGS with severe pain, the corresponding odds ratios were 2.6 (95% CI, 2.3-2.9) and 3.8 (95% CI, 3.3-4.3). CONCLUSION: The risk of the development of PGS increased with number of previous deliveries, which suggests that parity-related factors play a causal role.

Socio-demographic, psychosocial and health characteristics of Norwegian senior centre users: a cross-sectional study.

AIMS: The senior centre is the only welfare service in Norwegian elder care serving both fit and less functional pensioners over 65 years. The aim of the study was to determine the socio-demographic, psychosocial and health characteristics of users of the senior centres in relation to non-users in order to find out who can benefit from the senior centre service. METHODS: Data was collected from the Population Register for all persons living at home over 65 years in two municipal districts in Oslo. A random sample was drawn limited to 4,000 of the total number of residents over 65 years, 2,000 from each district. Questionnaires were sent by post. The response rate was 64% (n = 2,387). Psychological ailments were assessed using Hopkins Symptom Checklist-10 and social support with Oslo-3 Social Support Scale. RESULTS: The percentage of users was 44 among the survey respondents. Age was the most significant variable explaining use of the senior centre; increased age led to greater use. Single women used the senior centre more than married women while single men used it less than married men. Other predictors for women included osteoporosis, memory impairment and participation/interest from others. Memory impairment was a predictor for men. CONCLUSIONS: High age and specific health problems led to increased use. Living alone predicted greater use among women but less use among men. The association with age could not be explained through socio-demographic, psychosocial or health variables.

Nimotuzumab, an antitumor antibody that targets the epidermal growth factor receptor, blocks ligand binding while permitting the active receptor conformation.

Overexpression of the epidermal growth factor (EGF) receptor (EGFR) in cancer cells correlates with tumor malignancy and poor prognosis for cancer patients. For this reason, the EGFR has become one of the main targets of anticancer therapies. Structural data obtained in the last few years have revealed the molecular mechanism for ligand-induced EGFR dimerization and subsequent signal transduction, and also how this signal is blocked by either monoclonal antibodies or small molecules. Nimotuzumab (also known as h-R3) is a humanized antibody that targets the EGFR and has been successful in the clinics. In this work, we report the crystal structure of the Fab fragment of Nimotuzumab, revealing some unique structural features in the heavy variable domain. Furthermore, competition assays show that Nimotuzumab binds to domain III of the extracellular region of the EGFR, within an area that overlaps with both the surface patch recognized by Cetuximab (another anti-EGFR antibody) and the binding site for EGF. A computer model of the Nimotuzumab-EGFR complex, constructed by docking and molecular dynamics simulations and supported by mutagenesis studies, unveils a novel mechanism of action, with Nimotuzumab blocking EGF binding while still allowing the receptor to adopt its active conformation, hence warranting a basal level of signaling.

DNA binding kinetics of two response regulators, PlnC and PlnD, from the bacteriocin regulon of Lactobacillus plantarum C11.

BACKGROUND: Bacteriocin production in the lactic acid bacterium Lactobacillus plantarum C11 is regulated through a quorum sensing based pathway involving two highly homologous response regulators (59% identity and 76% similarity), PlnC as a transcriptional activator and PlnD as a repressor. Previous in vitro studies have shown that both regulators bind, as homodimers, to the same DNA regulatory repeats to exert their regulatory functions. As the genes for these two proteins are located on the same auto-regulatory operon, hence being co-expressed upon gene activation, it is plausible that their opposite functions must somehow be differentially regulated, either in terms of timing and/or binding kinetics, so that their activities do not impair each other in an uncontrolled manner. To understand the nature behind this potential differentiation, we have studied the binding kinetics of the two regulators on five target promoters (PplnA, PplnM, PplnJ, PplnE and PplnG) from the bacteriocin regulon of L. plantarum C11. RESULTS: By using surface plasmon resonance spectroscopy we obtained parameters such as association rates, dissociation rates and dissociation constants, showing that the two regulators indeed differ greatly from each other in terms of cooperative binding and binding strength to the different promoters. For instance, cooperativity is very strong for PlnC binding to the promoter of the regulatory operon (PplnA), but not to the promoter of the transport operon (PplnG), while the opposite is seen for PlnD binding to these two promoters. The estimated affinity constants indicate that PlnC can bind to PplnA to activate transcription of the key regulatory operon plnABCD without much interference from PlnD, and that the repressive function of PlnD might act through a different mechanism than repression of the regulatory operon. CONCLUSION: We have characterised the DNA binding kinetics of the two regulators PlnC and PlnD from the bacteriocin locus in L. plantarum C11. Our data show that PlnC and PlnD, despite their strong homology to each other, differ greatly from each other in terms of binding affinity and cooperativity to the different promoters of the pln regulon.

Education, sense of mastery and mental health: results from a nation wide health monitoring study in Norway.

BACKGROUND: Earlier studies have shown that people with low level of education have increased rates of mental health problems. The aim of the present study is to investigate the association between level of education and psychological distress, and to explore to which extent the association is mediated by sense of mastery, and social variables like social support, negative life events, household income, employment and marital status. METHODS: The data for the study were obtained from the Level of Living Survey conducted by Statistics Norway in 2002. Data on psychological distress and psychosocial variables were gathered by a self-administered questionnaire, whereas socio-demographic data were based on register statistics. Psychological distress was measured by Hopkins Symptom Checklist 25 items. RESULTS: There was a significant association between low level of education and psychological distress in both genders, the association being strongest in women aged 55-67 years. Low level of education was also significantly associated with low sense of mastery, low social support, many negative life events (only in men), low household income and unemployment,. Sense of mastery emerged as a strong mediating variable between level of education and psychological distress, whereas the other variables played a minor role when adjusting for sense of mastery. CONCLUSION: Low sense of mastery seems to account for much of the association between low educational level and psychological distress, and should be an important target in mental health promotion for groups with low level of education.

A model for the interaction between gadoid larvae and their nauplii prey.

A continuous model for the growth and death of gadoid larvae, including ecological interactions with their nauplii prey, is examined. The present model has a simpler structure than the model due to Cushing and Horwood [D.H. Cushing, J.W. Horwood, The growth and death of fish larvae. J. Plankt. Res. 16 (3) (1994) 291-300] as it does not explicitly incorporate larval metabolism, although indirectly metabolism is included by means of equations for larval growth. Despite this, the model yields related, although not entirely equivalent, results to those obtained by Cushing and Horwood. In the present model, overcompensation (cf. [W.E. Ricker, Stock and Recruitment, J. Fish. Res. Board. Can. 11 (1954) 559-623]) occurs at limited initial food levels, while at infinite food levels, the recruitment curve becomes monotonically increasing towards an upper limit (cf. [R.J.H. Beverton, S.J. Holt, On the dynamics of exploited fish populations. Fish. Invest. Lond. I 19 (1957)]). Moreover, the present study suggests that the duration of the larval stage, the metamorphosis time tau is highly important to the recruitment process, in accordance with Cushing and Horwood. When food is limited the metamorphosis is delayed, causing the larval population to experience (density dependent) mortality for a sufficient long time to make the recruitment curve overcompensatory. It is not necessarily the desire to derive a particular formula for the recruitment curve, as this is probably impossible anyway, except for particular examples. However, reduced versions of the model that in some sense are close to the original model, are examined, and it is argued that many general features of the general model are retained in such examples.