Distribution and determinants of retinol in Norwegian adolescents, and its relation to bone mineral density: the Tromsø Study: Fit Futures.

BACKGROUND/OBJECTIVES: Sufficient vitamin A levels are important for many functions-and both too little and too much may have detrimental health effects. The aim of the study was to describe the distribution of retinol levels in Norwegian adolescents, the relation between lifestyle factors and retinol levels, and the relation between retinol levels and bone mineral density (BMD). SUBJECTS/METHODS: Serum retinol was measured in 414 girls and 474 boys aged 15-19 years, participating in the Tromsø Study: Fit Futures. Questionnaires regarding health and lifestyle factors were filled in, and physical examinations, body composition, and bone mineral density measurements (DEXA) performed. Multiple regression analyses were used to discover associations between retinol and exposure variables. RESULTS: Retinol levels ranged from 0.26 to 6.46 µmol/L with a median (2.5-97.5 percentile) of 2.35 (1.01-4.67) µmol/L. There was no gender difference. In the multivariate models, fat mass, albumin level, physical activity, and lunch habits were positively associated with retinol levels in boys. In girls, fat mass and height were negatively associated with retinol levels, and lean mass, vitamin D, calcium, total cholesterol, and the use of contraceptives were positively associated with retinol levels (p < 0.05). The models explained 18.3% and 14.6% of the variation (R2) in girls and boys, respectively. Retinol levels were not independently associated with BMD. CONCLUSION: Retinol levels in Norwegian adolescents are higher than reported elsewhere, and are to a low degree explained by lifestyle and physical measurements. No independent association with BMD was found.

Biomarkers for nutrient intake with focus on alternative sampling techniques.

Biomarkers of nutrient intake or nutrient status are important objective measures of foods/nutrients as one of the most important environmental factors people are exposed to. It is very difficult to obtain accurate data on individual food intake, and there is a large variation of nutrient composition of foods consumed in a population. Thus, it is difficult to obtain precise measures of exposure to different nutrients and thereby be able to understand the relationship between diet, health, and disease. This is the background for investing considerable resources in studying biomarkers of nutrients believed to be important in our foods. Modern technology with high sensitivity and specificity concerning many nutrient biomarkers has allowed an interesting development with analyses of very small amounts of blood or tissue material. In combination with non-professional collection of blood by finger-pricking and collection on filters or sticks, this may make collection of samples and analyses of biomarkers much more available for scientists as well as health professionals and even lay people in particular in relation to the marked trend of self-monitoring of body functions linked to mobile phone technology. Assuming standard operating procedures are used for collection, drying, transport, extraction, and analysis of samples, it turns out that many analytes of nutritional interest can be measured like metabolites, drugs, lipids, vitamins, minerals, and many types of peptides and proteins. The advantage of this alternative sampling technology is that non-professionals can collect, dry, and mail the samples; the samples can often be stored under room temperature in a dry atmosphere, requiring small amounts of blood. Another promising area is the potential relation between the microbiome and biomarkers that may be measured in feces as well as in blood.

Intrathecal levels of vitamin D and IgG in multiple sclerosis.

BACKGROUND: Intrathecal synthesis of IgG is a hallmark of multiple sclerosis (MS). Vitamin D may modulate B-cell function and dampen the synthesis of IgG. OBJECTIVE: To investigate the relation between vitamin D levels in cerebrospinal fluid and serum and intrathecal synthesis of IgG. METHODS: 25-hydroxyvitamin D (25(OH)D) and IgG were assessed in cerebrospinal fluid and serum in 40 patients with MS. RESULTS: There was no significant correlation between the IgG index and 25(OH)D levels in cerebrospinal fluid or serum. The levels of 25(OH)D in cerebrospinal fluid and serum did not differ between patients with and without intrathecal synthesis of IgG. There was a non-significant trend towards a positive correlation between the concentrations of 25(OH)D and IgG in the cerebrospinal fluid, but not in serum. CONCLUSION: Physiological variation in vitamin D does not exert a major impact on intrathecal synthesis of IgG in MS.

High chromogranin A cell density in the colon of patients with lymphocytic colitis.

Microscopic colitis (MC) is a chronic condition that is characterized by watery diarrhoea with normal appearance of the colonic mucosa. MC is subdivided into two distinctive entities: lymphocytic colitis (LC) and collagenous colitis (CC). The etiology and pathophysiology of LC remain to be determined. The present study included 9 female patients with LC, with an average age of 34 years. Subjects (n=25) who underwent colonoscopy were used as controls. The subjects underwent colonoscopy due to gastrointestinal bleeding, where the source of bleeding was identified as haemorrhoids, or due to health concerns. The control subjects included 18 females and 7 males, with an average age of 49 years. Colonoscopy was performed in both patient and control groups, and biopsies were obtained from different segments of the colon. The biopsies were immunostained with the avidin-biotin complex method for human leucocytes CD45, collagen type III and chromogranin A (CgA). CgA was quantified by computer image analysis. The density of CgA-immunoreactive cells in patients with LC was significantly higher than that in controls. The high density of colonic CgA, a common marker for endocrine cells, indicates the possibility that colonic hormones are involved in the pathophysiology of LC. Serotonin-containing cells are the major endocrine cell type in the colon and constitute approximately 88% of the total endocrine cell population. It is likely that the increase in colonic CgA in LC patients accounts for an increase in serotonin cells.

Bile retinoids imprint intestinal CD103+ dendritic cells with the ability to generate gut-tropic T cells.

Small intestinal lamina propria (SI-LP) CD103(+) dendritic cells (DCs) are imprinted with an ability to metabolize vitamin A (retinol), a property underlying their enhanced capacity to induce the gut-homing receptors CC chemokine receptor-9 and α4ß7 on responding T cells. In this study, we demonstrate that imprinting of CD103(+) DCs is itself critically dependent on vitamin A and occurs locally within the small intestine (SI). The major vitamin A metabolite retinoic acid (RA) induced retinol-metabolizing activity in DCs both in vitro and in vivo, suggesting a direct role for RA in this process. Consistent with this, SI-LP CD103(+) DCs constitutively received RA signals in vivo at significantly higher levels than did colonic CD103(+) DCs. Remarkably, SI CD103(+) DCs remained imprinted in mice depleted of dietary but not of systemic retinol. We found that bile contained high levels of retinol, induced RA receptor-dependent retinol-metabolizing activity in bone marrow-derived DCs, and imprinted these cells with the ability to generate gut-tropic T cells. Taken together, these results suggest a novel and unexpected role for bile in SI-LP CD103(+) DC imprinting.

Sensor acceptance model - measuring patient acceptance of wearable sensors.

OBJECTIVES: This project focuses on how patients respond to wearable biomedical sensors, since patient acceptance of this type of monitoring technology is essential for enhancing the quality of the data being measured. There is a lack of validated questionnaires measuring patient acceptance of telemedical solutions, and little information is known of how patients evaluate the use of wearable sensors. METHODS: In information systems research, surveys are commonly used to evaluate the user satisfaction of software programs. Based on this tradition and adding measures of patient satisfaction and health-related quality of life (HRQoL), a Sensor Acceptance Model is developed. The model is made operational using two questionnaires developed for measuring the patients' perceived acceptance of wearable sensors. RESULTS: The model is tested with 11 patients using a newly developed wearable ECG sensor, and with 25 patients in a reference group using a traditional "Holter Recorder". Construct validity is evaluated by confirmatory factor analysis, and internal consistency is calculated using the Cronbach's alpha coefficient. Sensor Acceptance Index (SAI) is calculated for each patient, showing reasonable dependencies and variance in scores. CONCLUSIONS: This study attempts to identify patients' acceptance of wearable sensors, describing a user acceptance model. Understanding the patients' behavior and motivation represents a step forward in designing suitable technical solutions, and calculations of SAI can, hopefully, be used to compare different wearable sensor solutions. However, this instrument needs more extensive testing with a broader sample size, with different types of sensors and by explorative follow-up interviews.

Stability of whole blood and plasma ascorbic acid.

The objective of this study was to evaluate the impact of pre-analytical factors on the short and long term stability of ascorbic acid (AA), the main form of vitamin C in whole blood and plasma. The effects of various anticoagulants, acidification, storage temperature and time were tested. A recently developed fast and sensitive HPLC method was used to measure AA levels. AA baseline values observed in heparin plasma were significantly higher than values observed in EDTA, citrate and Stabilyte plasma, as well as in serum. pH and temperature were identified as additional critical pre-analytical factors during the short, medium and long term handling and storage. Thus, assessment of reliable and accurate AA status in biological samples demonstrates to be highly dependent on whether the initial conditions during sample handling are controlled. In conclusion, heparin tubes should be used for blood sample collection. As AA is rapidly degraded, sample collection should be followed by immediate centrifugation and plasma acidification. To avoid further degradation during sample handling, samples should be stored at -70 degrees C without delay and analyzed within 80 days.

Quantitative axial profiles of retinoic acid in the embryonic mouse spinal cord: 9-cis retinoic acid only detected after all-trans-retinoic acid levels are super-elevated experimentally.

Studies using bioassays in normal mice and gene activation in transgenic reporter mice have demonstrated peaks of retinoic acid receptor (RAR) signaling in the brachial and lumbar regions of the spinal cord. Recently, Solomin et al. (Solomin et al. [1998] Nature 395:398-402) detected a retinoid X receptor (RXR) signal in the same region of the developing spinal cord at a slightly later stage than the RAR signal. This finding raises the question of which retinoid ligands underlie RAR and RXR signaling in this part of the embryo. Quantitative measurements of regional differences in retinoid profiles have not been reported previously due to limitation in the sensitivity and specificity of available retinoid detection methods. Here, by using a recently developed ultrasensitive HPLC technique (Sakhi et al. [1998] J. Chromatogr. A 828:451-460), we address this question in an attempt to identify definitively the endogenous retinoids present in different regions of the spinal cord at the stages when regional differences in RAR and RXR signaling have been reported. We find a bimodal distribution of all-trans retinoic acid (at-RA), the ligand for RARs, and relate this to the expression of several retinoid-synthesizing enzymes. However, we do not detect 9-cis-retinoic acid (9-cis-RA), the putative RXR ligand, in any region of the spinal cord unless retinoid levels are massively increased experimentally by gavage feeding pregnant mice with teratogenic doses of at-RA. This study provides for the first time quantitative profiles of endogenous retinoids along the axis of the developing spinal cord, thereby establishing a foundation for more definitive studies of retinoid function in the future. It sets definite limits on how much 9-cis-RA potentially is present and demonstrates that at-RA predominates over 9-cis-RA by at least 30- to 180-fold in different spinal cord regions.

Quantitative assessment of retinoid signaling pathways in the developing eye and retina of the chicken embryo.

Retinoid signaling has been implicated as an important regulator of retinal development and differentiation. We have used state of the art high-pressure liquid chromatography to identify and quantitate biologically active retinoids, immunohistochemistry to localize the retinoic acid synthetic enzyme retinaldehyde dehydrogenase 2 (RALDH2), and nucleic acid assays to quantitate and localize retinoid receptor gene transcripts in the developing eye and retina of the chicken. Our results demonstrate spatial distinctions in retinoid synthesis and signaling that may be related to laminar differentiation in the developing retina. Retinoic acids (RAs) and their precursor retinols (ROHs) are the predominant retinoids in the developing eye. All-trans-RA and all-trans-3,4-didehydro-RA are present in the neuroepithelium in approximately equal amounts from early stages of neurogenesis until shortly before hatching. The retinoid X receptor (RXR) ligand 9-cis-RA is undetectable at all stages; if present, it cannot exceed a small percentage of the total RA content. RAs are not detected in the pigment epithelium. All-trans-ROH is present in the neuroepithelium and pigment epithelium, whereas all-trans-3,4-didehydro-ROH is detected only in the pigment epithelium and/or the choroid and sclera. RALDH2 immunoreactivity is intense in the choroid, low or absent in the pigment epithelium, and moderate in the neuroepithelium, where it is highest in the outer layers. Transcripts of all five chicken retinoid receptor genes are present in the neural retina and eye throughout development. During the period of neurogenesis, at least three of the receptors (RAR gamma, RXR gamma, RXRalpha), exhibit dynamic patterns of differential localization within the depths of the neural retina.

Qualitative and quantitative liquid chromatographic determination of natural retinoids in biological samples.

Liquid chromatography continues to be the preferred method for determining retinoids in biological samples. The highly unstable nature of retinoids and the real possibility of artifacts or erroneous results have led to the development of rapid and highly automated protocols for retinoid extraction, separation and detection. Due to strong light absorbance in the ultraviolet region, UV detectors still predominate although mass spectrometric detection is gaining increased popularity. This paper reviews recent advances and provides major guidelines for using liquid chromatography to identify and quantify retinoids in biological samples.

[Oxygen therapy of patients with chronic obstructive pulmonary disease reduces the development of pulmonary hypertension]. / Oksygenbehandling av pasienter med kronisk obstruktiv lungesykdom reduserer utvikling av pulmonal hypertensjon.

The development of secondary pulmonary hypertension in patients with chronic obstructive pulmonary disease worsens their prognosis; oxygen therapy seems to improve prognosis in these patients. We measured the effect of oxygen therapy on mean pulmonary artery pressure in four women and four men aged 64 to 82 years (average 73 years) with chronic obstructive pulmonary disease. A right cardiac catheterisation was performed before and on average 11 months (8-16 months) after start of oxygen therapy. The mean pulmonary artery pressure decreased on average 5 mm Hg, from 24 to 19 mm Hg. As prognosis seems to be associated with pulmonary artery pressure, more patients with chronic obstructive pulmonary disease should be evaluated for oxygen therapy.

New HPLC evidence on endogenous tauret in retina and pigment epithelium.

This investigation was improve the separation for tauret (retinylidene taurine) and to compare its content in the retina under dark and light adaptation. To prevent tauret hydrolysis, retinal samples were quickly frozen and lyophilized. Methanol extracts of dried retina and pigment epithelium from both dark- or light-adapted frogs, Rana ridibunda, were injected onto HPLC. Synthetic standard tauret appeared at 4.7 min after the solvent front. At the same time, an endogenous substance was eluted from the mixed retinal and pigment epithelial samples. The UV spectra of this endogenous compound matched with the spectra of synthetic tauret obtained under identical conditions, with lambda(max) = 446 nm at peak. We conclude that the HPLC system used permitted full separation of tauret from the methanol extracts of the retina and pigment epithelium. TLC and further HPLC analysis have shown that tauret quantities were several times higher in the retina and pigment epithelium of the frogs adapted to dark compared with those light-adapted (about 4 h under 1000 1x illumination). Tauret based vitamin A transport is probably involved in other systems as well, where along with its other known beneficial effects taurine probably is necessary to facilitate vitamin A transport.

Identification of endogenous retinoids, enzymes, binding proteins, and receptors during early postimplantation development in mouse: important role of retinal dehydrogenase type 2 in synthesis of all-trans-retinoic acid.

Specific combinations of nuclear retinoid receptors acting as ligand-inducible transcription factors mediate the essential role of retinoids in embryonic development. Whereas some data exist on the expression of these receptors during early postimplantation development in mouse, little is known about the enzymes controlling the production of active ligands for the retinoid receptors. Furthermore, at early stages of mouse development virtually no data are available on the presence of endogenous retinoids. In the present study we have used a recently developed high-performance liquid chromatographic (HPLC) technique to identify endogenous retinoids in mouse embryos down to the egg cylinder stage. All-trans-retinoic acid, a ligand for the retinoic acid receptors, was detected in embryos dissected as early as 7.5 dpc (i.e., a combination of midstreak until late allantoic bud stage embryos). At these stages, we detected mRNA coding for all the retinoid receptors, retinoid binding proteins, and two enzymes able to convert retinol to retinal (retinol dehydrogenase 5 (RDH5) and alcohol dehydrogenase 4 (ADH4)). We also detected retinal dehydrogenase type 2 (RALDH2), an enzyme capable of oxidising the final step in the all-trans-retinoic acid synthesis. In egg cylinder stage mouse embryos no all-trans-retinoic acid was detected. However, at this stage its precursor all-trans-retinal was present. In accordance with these HPLC observations, RDH5 and ADH4 were expressed, but no transcripts coding for enzymes that oxidise retinal to retinoic acid. Therefore, our results suggest that RALDH2 is a key regulator in initiating retinoic acid synthesis sometime between the mid-primitive streak stage and the late allantoic bud stage in mouse embryos.

[Chronic heart failure--suggestion to a management program]. / Kronisk hjertesvikt--forslag til handlingsprogram.

In 1994, a Norwegian programme for diagnosis and treatment of chronic heart failure was published. Recently the American College of Cardiology, the American Heart Association and the Task Force on Heart Failure of the European Society of Cardiology have published similar guidelines. In this article, the Working Group on Heart Failure of the Norwegian Society of Cardiology presents an updated programme for evaluation and management of patients with chronic heart failure.

Felodipine-metoprolol combination tablet: a valuable option to initiate antihypertensive therapy?

The aim of the present study was to assess the efficacy and tolerability of a calcium antagonist/beta-blocker fixed combination tablet used as first-line antihypertesnive therapy in comparison with an angiotensin converting enzyme inhibitor and placebo. Patients with uncomplicated essential hypertension (diastolic blood pressure between 95 and 110 mm Hg at the end of a 4-week run-in period) were randomly allocated to a double-blind, 12-week treatment with either a combination tablet of felodipine and metoprolol (Logimax), 5/50 mg daily (n = 321), enalapril, 10 mg daily (n = 321), or placebo (n = 304), with the possibility of doubling the dose after 4 or 8 weeks of treatment if needed (diastolic blood pressure remaining >90 mm Hg). The combined felodipine-metoprolol treatment controlled blood pressure (diastolic < or =90 mm Hg 24 h after dose) in 72% of patients after 12 weeks, as compared with 49% for enalapril and 30% for placebo. A dose adjustment was required in 38% of patients receiving the combination, in 63% of patients allocated to placebo, and 61% of enalapril-treated patients. The overall incidence of adverse events was 54.5% during felodipine-metoprolol treatment; the corresponding values for enalapril and placebo were 51.7% and 47.4%, respectively. Withdrawal of treatment due to adverse events occurred in 18 patients treated with the combination, in 10 patients on enalapril, and 12 patients on placebo. No significant change in patients' well-being was observed in either of the three study groups. These results show that a fixed combination tablet of felodipine and metoprolol allows to normalize blood pressure in a substantially larger fraction of patients than enalapril given alone. This improved efficacy is obtained without impairing the tolerability. The fixed-dose combination of felodipine and metoprolol, therefore, may become a valuable option to initiate antihypertensive treatment.

The impact of an end-point committee in a large multicentre, randomized, placebo-controlled clinical trial: results with and without the end-point committee's final decision on end-points.

BACKGROUND: A multicentre study permits rapid recruitment of a large number of patients. However, there is a risk of heterogeneities in end-point evaluations, as complex definitions of criteria are interpreted by several local investigators from different hospitals. Reports discussing end-point evaluation are sparse. The TRIM trial was a multicentre trial of a thrombin inhibitor in patients with unstable angina or non-Q myocardial infarction. In this study, an independent end-point committee evaluated all the reported events of death, acute myocardial infarction and refractory angina pectoris in order to obtain uniform judgements of major end-points. STUDY AIMS: To describe the work of the end-point committee, to analyse its possible effect on the final study results and to discuss the impact on the design of future trials. METHOD: The end-point committee consisted of four members, one from each participating country. After the data were processed by the study monitors, completed case record forms and patient files for patients with reported end-points were mailed to the national member of the end-point committee for judgement. The end-point committee met regularly and made final decisions about the end-points. The work of the end-point committee was documented on a separate case record form. RESULTS: The end-point committee assessed 246 events of death, acute myocardial infarction and refractory angina pectoris in 187 of the 1209 patients (15.5%) in the TRIM trial. Misinterpretation of the index event, an inclusion myocardial infarction, as an early cardiac event was found in 12 patients. After end-point committee judgements, the number of patients with acute myocardial infarction or refractory angina pectoris during 30 days of follow-up was reduced from 177 to 153 (13. 6% reduction). The classification of events was changed in 53 of 187 patients (28.3%) with death, acute myocardial infarction or refractory angina pectoris. The data assessed by the safety committee was significantly different from the final database after end-point committee judgements. CONCLUSION: The end-point committee corrected misinterpretations in such a high proportion of cases that the final results differed significantly from the preliminary results delivered to the safety committee. End-point judgements by an end-point committee should be performed in multicentre clinical trials to improve the quality and reliability of study results.

Evidence for an essential role of megalin in transepithelial transport of retinol.

Transepithelial transport of retinol is linked to retinol-binding protein (RBP), which is taken up and also synthesized in a number of epithelia. By immunocytochemistry of human, rat, and mouse renal proximal tubules, a strong staining in apical endocytic vacuoles, lysosomes, endoplasmic reticulum, Golgi, and basal vesicles was observed, in accordance with luminal endocytic uptake as well as a constitutive synthesis and basal secretion of RBP. Analysis of mice with target disruption of the gene for the major endocytic receptor of proximal tubules, megalin, revealed no RBP in proximal tubules of these mice. Western blotting and HPLC of the urine of the megalin-deficient mice instead revealed a highly increased urinary excretion of RBP and retinol, demonstrating that glomerular filtered RBP-retinol of megalin-deficient mice escapes uptake by proximal tubules. A direct megalin-mediated uptake of purified RBP-retinol was indicated by surface plasmon resonance analysis and uptake in immortalized rat yolk sac cells. Uptake was partially inhibited by a polyclonal megalin antibody and the receptor-associated protein. The present data show that the absence of RBP-binding megalin causes a significantly increased loss of RBP and retinol in the urine, demonstrating a crucial role of megalin in vitamin A homeostasis.

On-line solid-phase extraction and isocratic separation of retinoic acid isomers in microbore column switching system.

On-line solid-phase extraction coupled with micro-HPLC by column switching is an ideal technique for the analysis of retinoic acid in serum or plasma. The advantages are mainly contributed to an automated sample workup and low detection limits. On-line processing of the sample ensures minimal losses and full light protection during the entire procedure. Critical steps such as evaporation, extraction, and multiple transfers are avoided. Furthermore, the precision of highly automated methods is generally better than manual methods. We have successfully coupled a 2.1-mm I.D. analytical column with a 2.1-mm extraction column. This setup allows for large amounts of supernatant to be injected onto precolumns for concentration and cleanup. By means of column switching, this concentrate is transferred to the microcolumn with a highly reduced volume. The reduced diameter of the analytical column and the on-line solid-phase extraction allow for the fully automated quantification of as little as 100 fmol all-trans-retinoic acid in human serum. The detection limits obtained with these column switching techniques can compete with LC-MS. This new micro-HPLC method will be useful for the quantitation of endogenous retinoic acid metabolites, which are present at very low concentrations in biological material. Furthermore, more sensitive methods might also lead to the discovery of hitherto unknown retinoic acid metabolites. The combination of on-line SPE and micro-HPLC has, to our knowledge, not been used previously for retinoic acid analysis. The development of isocratic separation methods for retinoic acid isomers made this possible.

[Cardiopulmonary complications in acute subarachnoid hemorrhage]. / Kardiopulmonale komplikasjoner ved subaraknoidalblødning.

Pathologic electrocardiogram (ECG) may be present in more than 90% of patients with subarachnoid haemorrhage. The ECG findings are often transient and may mimic acute myocardial ischaemia or infarction. These ECG findings may cause diagnostic problems in patients with subarachnoid haemorrhage who are unconscious or who have atypical symptoms. Life-threatening arrhythmias are also seen and may be responsible for sudden deaths in patients with subarachnoid haemorrhage. Other signs of myocardial injury, such as ventricular wall motion dysfunction, elevated enzymes, and histological evidence of contraction band necrosis are described. The myocardial dysfunction known as neurogenic stunned myocardium is reversible if the patient survives the acute phase, but it may lead to haemodynamic instability and contribute to the origin of neurogenic pulmonary oedema. The myocardial injury in subarachnoid haemorrhage may be due to a massive sympathetic stimulation of the myocardium in response to rapidly increasing intracranial pressure. We illustrate myocardial injury and dysfunction in a case report where a patient had subarachnoid haemorrhage with ventricular fibrillation, pulmonary oedema, left ventricular dysfunction and ST-segment elevation, initially thought to be acute myocardial infarction.