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Biomedical subjects

S Karlsson

Publications and source records attributed to S Karlsson.

At least 91 records · Page 5Linked to original sources
PubMed1998

Evidence for contribution by increased cytoplasmic Na+ to the insulinotropic action of PACAP38 in HIT-T15 cells.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is localized to pancreatic nerve terminals and stimulates insulin secretion. The insulinotropic effect of PACAP38 in insulin-producing HIT-T15 cells is accompanied by increases in cellular cAMP and cytoplasmic Ca2+ ([Ca2+]cyt). As also intracellular Na+ is important for insulin secretion after glucose and other cAMP forming peptides, we examined the Na+ dependence of the insulinotropic effect of PACAP38 in HIT-T15 cells. We found that PACAP38 (100 nM)-induced insulin secretion was diminished by approximately 50% by removal of extracellular Na+ (replaced by equimolar N-methyl-D-glucamine). In contrast, removal of Na+ did not diminish the formation of cellular cAMP (measured by radioimmunoassay) or the increase in [Ca2+]cyt (measured in FURA-2AM-loaded cell suspensions) induced by PACAP38. Furthermore, PACAP-38 increased the cytoplasmic Na+ ([Na+]cyt) in single HIT-T15 cells as measured by the fluorophore sodium-binding benzofran isophthalate. This increase was reduced by removal of extracellular Na+ and by inhibition of protein kinase A by H-89. We conclude that the insulinotropic action of PACAP38 is Na+-dependent. We propose that PACAP38 opens plasma membrane Na+ channels by an action partially mediated by cAMP and protein kinase A, and the subsequent raise in [Na+]cyt elicits insulin secretion by an as yet unsolved mechanism.

Animals↗
PubMed1998

CCK receptor subtype in insulin-producing cells: a combined functional and in situ hybridization study in rat islets and a rat insulinoma cell line.

Cholecystokinin (CCK) stimulates insulin secretion. It is, however, not established whether CCK receptors are expressed in insulin-producing cells. We therefore investigated, by in situ hybridization, whether CCK-A or CCK-B receptor mRNA could be detected in normal rat pancreatic islets and in the rat insulinoma cell line, RINm5F. The CCK-A, but not the CCK-B, receptor transcript was detected in both islets and RINm5F cells. Islet CCK-A receptors were mostly confined to the center of the islets corresponding to the distribution of the B cells. In RINm5F cells, insulin release was not significantly affected by cholecystokinin (CCK)-8-S (10(-13) to 10(-7) M), which is in contrast to the insulinotropic effect of CCK-8-S in normal rat islets. Similarly, in FURA-2AM-loaded cells, CCK-8-S (10(-11) to 10(-7) M) was without effect on the intracellular Ca2+ concentration ([Ca2+]ic) in RINm5F cells, whereas CCK-8-S (10(-7) M) markedly increased [Ca2+]ic (by 366+/-2 nM (P < 0.001) in normal rat islet cells. We conclude that the CCK-A, but not the CCK-B, receptor subtype is expressed in both normal rat islets and in the rat insulinoma-derived cell line RINmS5F. There is, however, a functional difference between normal islets and the RINm5F cells with respect to effects of CCK-8-S on insulin release and [Ca2+]ic.

Animals↗
PubMed1998

Retroviral transfer of the glucocerebrosidase gene into CD34+ cells from patients with Gaucher disease: in vivo detection of transduced cells without myeloablation.

Retroviral gene transfer of the glucocerebrosidase gene to hematopoietic progenitor and stem cells has shown promising results in animal models and corrected the enzyme deficiency in cells from Gaucher patients in vitro. Therefore, a clinical protocol was initiated to explore the safety and feasibility of retroviral transduction of peripheral blood (PB) or bone marrow (BM) CD34+ cells with the G1Gc vector. This vector uses the viral LTR promoter to express the human glucocerebrosidase cDNA. Three adult patients have been entered with follow-up of 6-15 months. Target cells were G-CSF-mobilized and CD34-enriched PB cells or CD34-enriched steady state BM cells, and were transduced ex vivo for 72 hr. Patient 1 had PB cells transduced in the presence of autologous stromal marrow cells. Patient 2 had PB cells transduced in the presence of autologous stroma, IL-3, IL-6, and SCF. Patient 3 had BM cells transduced in the presence of autologous stroma, IL-3, IL-6, and SCF. At the end of transduction, the cells were collected and infused immediately without any preparative treatment of the patients. The transduction efficiency of the CD34+ cells at the end of transduction was approximately 1, 10, and 1 for patients 1, 2, and 3, respectively, as estimated by semiquantitative PCR on bulk samples and PCR analysis of individual hematopoietic colonies. Gene marking in vivo was demonstrated in patients 2 and 3. Patient 2 had vector-positive PB granulocytes and mononuclear bone marrow cells at 1 month postinfusion and positive PB mononuclear cells at 2 and 3 months postinfusion. Patient 3 had a positive BM sample at 1 month postinfusion but was negative thereafter. These results indicate that gene-marked cells can engraft and persist for at least 3 months postinfusion, even without myeloablation. However, the level of corrected cells (<0.02%) is too low to result in any clinical benefit, and glucocerebrosidase enzyme activity did not increase in any patient following infusion of transduced cells. Modifications of vector systems and transduction conditions, along with partial myeloablation to allow higher levels of engraftment, may be necessary to achieve beneficial levels of correction in patients with Gaucher disease.

Adult↗
PubMed1998

Insulin and glucagon secretion by ganglionic nicotinic activation in adrenalectomized mice.

The pancreatic islets are innervated by nerves emanating from intra- and extrapancreatic ganglia. However, the effects of ganglionic activation on insulin and glucagon release in vivo have not been established. We therefore investigated the effects of pharmacological ganglionic activation by the nicotinic agonists DMPP (1,1-dimethyl-4-phenylpiperazinium iodide) and nicotine on insulin and glucagon release in sham-operated and adrenalectomized mice. In sham-operated animals, DMPP (0.5 or 1.6 micromol/kg, i.v.) or nicotine (0.075 or 0.75 micromol/kg, i.v.), did not affect plasma insulin levels, but markedly increased plasma glucagon levels (P < 0.05). In contrast, after adrenalectomy or alpha2-adrenoceptor blockade by yohimbine (3.6 micromol/kg), nicotinic activation markedly increased plasma insulin levels (P < 0.05), whereas the glucagon response to nicotinic activation was inhibited under these conditions (P < 0.05). We conclude that pharmacological ganglionic nicotinic activation in mice stimulates insulin and glucagon secretion. The insulinotropic effect is, however, counteracted by a concomitant adrenal activation through an alpha2-adrenoceptor-mediated mechanism.

Adrenalectomy↗
PubMed1998

One-year reproducibility and stability of the signal amplitude ratio and other variables of the electromyogram: test-retest of a shoulder forward flexion test in female workers with neck and shoulder problems.

We have studied 23 women with neck and shoulder problems in a car factory with a 1-year interval. Our main aim was to investigate the reproducibility and stability of the tension pattern. In addition, the mean frequency (MNF) of the power spectrum and the signal amplitude (RMS) of the surface electromyograph (EMG) of the trapezius, deltoid and infraspinatus muscles and mechanical output were determined throughout 100 maximal isokinetic shoulder forward flexions. The signal amplitude ratio (SAR) was calculated as the ratio between the signal amplitude of the EMG of the passive relaxation and the active flexion part of each contraction cycle. The SAR variable can be reproduced (r = 0.47-0.76) with a 1-year interval. There was a significantly lower SAR of the trapezius at the second test, which might have been due to lower work pace at the factory. The longitudinal patterns of SAR throughout the two tests were similar at both tests. There were significant correlations between tests for 18 out of 22 EMG variables, even though the correlations were generally lower than for SAR (initial MNF: r = 0.39-0.48; MNF endurance level: r = 0.55-0.83; RMS (%): r = 0.08-0.46). Peak torque had better reproducibility than work. In conclusion, SAR has a long-term reproducibility equal to or better than other EMG and biomechanical variables. The present results indicate that SAR has potential to measure unnecessary muscle tension in intervention studies and to identify individual movement patterns.

Electromyography↗
PubMed1998

Self-assessed masticatory ability in relation to maximal bite force and dental state in 80-year-old subjects.

By means of a questionnaire, clinical examination and force recordings, the relationships between self-assessed masticatory ability, dental state and bite force were studied in 160 80-year-old persons, 74 men and 86 women. The subjects were in general satisfied with their masticatory ability and 70% had no problems, while 6% reported three or more problems with mastication. Half of the subjects were dentate without removable prostheses and almost one-third had 20 or more natural teeth. The edentulous persons (about one-fifth of all) reported more problems related to mastication than the other dentition groups. The maximal bite force varied much and exhibited a significant correlation to the number of remaining teeth and dental state. The self-assessed masticatory ability was only weakly correlated with dental state and bite force. It was concluded that many subjects with few or no remaining teeth and/or removable dentures had only few complaints of impaired masticatory function and showed a good adaptation to an impaired dental status and small maximal bite force.

Adaptation, Physiological↗
PubMed1998

Relationship of masticatory mandibular movements to masticatory performance of dentate adults: a method study.

This study evaluated a sieve method for measuring masticatory performance and determined the associations between masticatory performance and masticatory mandibular movements. Ten dentate adults and three complete denture-wearing subjects participated in the study. The masticatory performance indices for these subjects were determined after a 10 s masticatory sequence and another sequence that ended at the swallowing threshold. Almond was used as the test food and almond fragments were sized using a standard 0.65 mm square size brass wire sieve. Masticatory mandibular movements were simultaneously recorded by an optoelectronic device. The reproducibility of the masticatory performance tests was good (r = 0.98 and 0.82 for the 10 s and swallowing threshold test indices, respectively). The masticatory performance indices were markedly different between dentate and denture-wearing subjects. The 10 s masticatory performance index in the dentate subjects, showed moderate to rather strong correlation with all parameters of mandibular velocity (r = 0.6-0.7). The 10 s index also showed a strong negative correlation to the duration of the occlusal level phase and the total duration of the chewing cycle (r = -0.7 to -0.8) in the dentate subjects. This study confirms that masticatory performance levels are relatively stable and associated with the efficacy of specific masticatory mandibular movement parameters.

Adult↗
PubMed1998

Insulin secretion by gastrin-releasing peptide in mice: ganglionic versus direct islet effect.

Gastrin-releasing peptide (GRP) stimulates insulin secretion by a direct islet effect. In this study, we initially demonstrated, by immunocytochemistry of the mouse pancreas, GRP immunoreactive nerve fibers within exocrine tissue, islets, and intrapancreatic ganglia. A more pronounced GRP innervation was found in ganglia compared with in islets. We therefore studied whether indirect cholinergic mechanisms contribute to the insulinotropic action of GRP. In mice, the insulinotropic response to GRP (4.25 nmol/kg i.v.) was inhibited by the m3-selective, muscarinic receptor antagonist 4-diphenylacetoxy-N-methyl piperidine methobromide (4-DAMP, 0.21 mol/kg; by 68%, P < 0.05) and by the ganglionic blocker hexamethonium (28 mol/kg; by 98%, P < 0.05). In contrast, in isolated islets, 4-DAMP or hexamethonium (10 or 100 microM) did not inhibit GRP (100 nM)-induced insulin secretion. Furthermore, afferent denervation by neonatal capsaicin did not affect the insulin response to GRP. We conclude that the insulinotropic effect of GRP in the mouse is mediated by both direct islet effects and through activation, at the ganglionic level, of postganglionic cholinergic nerves. In vivo, the indirect cholinergic mechanism predominates.

Animals↗
PubMed1998

Ca2+-independent phospholipase A2 contributes to the insulinotropic action of cholecystokinin-8 in rat islets: dissociation from the mechanism of carbachol.

Insulin secretion induced by cholecystokinin-8 (CCK-8) was recently suggested to involve phospholipase A2 (PLA2) activation. In this study, we examined whether CCK-8 stimulates the Ca2+-independent form of PLA2 in isolated rat islets, in comparison with stimulation by the PLA2-activating cholinergic agonist carbachol. We found that CCK-8 (100 nmol/l; 5.6 mmol/l glucose) induces lysophosphatidylcholine accumulation from [3H]palmitate-prelabeled islets (170 +/- 39%; P = 0.003) as well as arachidonic acid (AA) efflux from [3H]AA-prelabeled islets (190 +/- 13%; P < 0.001), and that p-amylcinnamoylantranilic acid (ACA) (50 micromol/l)-mediated PLA2 inhibition reduces CCK-8-induced AA efflux (52 +/- 11%; P = 0.001) and insulin secretion (67 +/- 16%; P < 0.001). Neither the Ca2+ channel antagonist verapamil (100 micromol/l) nor the Ca2+ATPase inhibitor thapsigargin (1 micromol/l) affected CCK-8-induced AA efflux and insulin secretion. Furthermore, despite removal of extracellular Ca2+, CCK-8 still increased AA efflux (48 +/- 14%; P = 0.006) and insulin secretion (105 +/- 46%; P = 0.025). In contrast, carbachol (100 micromol/l)-stimulated AA efflux was reduced by verapamil by 36 +/- 6% (P < 0.001) and abolished by removal of extracellular Ca2+. Overnight protein kinase C (PKC) downregulation by 12-O-tetradecanoyl phorbol-13-acetate (TPA) (500 nmol/l) reduced CCK-8-induced AA efflux (45 +/- 12%; P = 0.003) and insulin secretion (40 +/- 16%; P = 0.020). No additive action regarding either AA formation or insulin secretion was seen by combining TPA overnight and ACA, which implies the involvement of an additional PLA2- and PKC-independent signaling mechanism. The results show that CCK-8, in contrast to carbachol, activates Ca2+-independent PLA2 in islets and that the PLA2-activating capacity of CCK-8 is partly PKC dependent. Hence, Ca2+-independent PLA2 seems important for the insulinotropic effect of CCK-8, but not for that of carbachol.

Animals↗
PubMed1998

Genotoxicity studies with the antiestrogen toremifene.

Toremifene, a second-generation triphenylethylene antiestrogen used clinically in the chemotherapy of breast cancer and some other cancers, differs in its nonclinical toxicology from its first-generation congener tamoxifen. Tamoxifen produces DNA adducts and tumors in rat liver, whereas assays for DNA adduct formation with toremifene have been negative to weakly positive, and toremifene does not produce liver tumors in rats. To evaluate further toremifene for possible genotoxicity, it was tested in three standard, in vitro assay--reversion of bacterial point mutations, unscheduled DNA synthesis in cultured hepatocytes from two rat strains, and cytogenetics of human lymphocytes in primary culture--and in one in vivo assay, the mouse, erythrocyte micronucleus assay. The three in vitro assays were conducted with toremifene at up to the limit of cytotoxicity (100 to 250 micrograms/ml, depending on the system). The bacterial mutagenicity and lymphocyte chromosome aberration assays were performed both in the presence and absence of metabolic activation by Araclor-induced, rat liver S-9, while the hepatocyte unscheduled DNA synthesis assay provides intrinsic bioactivation. To test for chromosome damage in vivo, mice were administered up to 2g/kg toremifene once by gavage, and bone marrow was harvested daily, for three days. Normochromatic and polychromatic bone marrow erythrocytes were examined for micronuclei. Toremifene lacked genotoxicity or myelotoxicity detectable by any of the above assays. These findings, together with the reported absence of DNA binding in rat liver, provide evidence that toremifene is not genotoxic.

Animals↗
PubMed1998

Physical restraints in geriatric care. Knowledge, attitudes and use.

The aim of the present study was to investigate the use of physical restraints in institutional elder care and staff knowledge about and attitudes toward the use of these restraints. Poor knowledge and negative attitudes toward the use of restraints were found among staff. Significant differences between various staff categories were found concerning knowledge about the use of restraints; nurse aids had the lowest and physicians the highest scores on the knowledge test. Nurse aids demonstrated the least negative attitudes (were most prone to use restraints) and physicians the most negative. Furthermore, there was a significant relation between attitudes and knowledge, i.e. staff with poor knowledge also demonstrated the least negative attitudes toward the use of restraints. Despite these negative attitudes among staff, we found a large proportion of restrained patients in the institutions investigated. Twenty-nine percent of the patients at the investigated clinics were physically restrained. The most common reason given was that restraints were used to prevent falls. No documentation of the observed use of restraints was found in any of the restrained patients' hospital records.

Adult↗
PubMed1997

Dexamethasone induces neuropeptide Y (NPY) expression and impairs insulin release in the insulin-producing cell line RINm5F. Release of NPY and insulin through different pathways.

Neuropeptide Y (NPY) occurs in adrenergic as well as in non-adrenergic nerves innervating the islets of Langerhans and inhibits glucose-stimulated insulin secretion. Recently we demonstrated that NPY is expressed within islet beta cells of the rat pancreas following treatment with dexamethasone in vivo. In this study we examined the cellular expression of NPY following dexamethasone treatment of the insulin-producing cell line RINm5F, which under control conditions does not express or release NPY. The cells were cultured with or without dexamethasone (100 nM) for 5 days. Over the 5-day culture period, dexamethasone time dependently induced an increased release of NPY with a concomitant decrease in the release of insulin. Northern blot and in situ hybridization revealed a corresponding time-dependent increase in the amount of NPY transcripts and in the number of cells labeled for NPY mRNA, whereas immunocytochemistry for NPY revealed only a few immunoreactive cells, indicating a rapid release of the formed peptide. Following 5 days of culture with dexamethasone, acute stimulation with D-glyceraldehyde (10 mM) or KCl (20 mM) Ca2+ dependently stimulated the release of insulin. In contrast neither stimulation with D-glyceraldehyde or KCl nor removal of extracellular Ca2+ affected the release of NPY. Furthermore the D-glyceraldehyde- and KCl-induced increase in cytosolic Ca2+, evident in control RINm5F cells, was impaired after dexamethasone treatment. We conclude that RINm5F cells show steroid-sensitive plasticity and express NPY after dexamethasone treatment concomitantly with a decreased insulin secretion and impaired increase in cytosolic Ca2+ upon depolarization with KCl or stimulation with D-glyceraldehyde. We also conclude that NPY and insulin secretion are regulated differently and suggest that the inability of the removal of extracellular Ca2+ to inhibit NPY secretion and the failure of D-glyceraldehyde and KCl to stimulate NPY secretion reflect a constitutive release of this peptide from the cells in contrast to the regulated release of insulin.

Animals↗
PubMed1997

Viral vectors for gene therapy of hematopoietic cells.

Hematopoietic cells, in particular hematopoietic stem cells, are important targets for the development of gene therapy for hematological and other disorders. So far, simple retroviral vectors based on Murine Leukemia Virus (MLV) have been the main delivery vehicles for the transfer of corrective genes into primary hematopoietic cells. While the gene transfer efficiency of progenitor cells has been very efficient using these vectors, it has been much more problematic to obtain efficient gene transfer into repopulating human hematopoietic stem cells. The main reason for this is due to the quiescent nature of these cells and the fact that MLV-based vectors require dividing target cells. It may be that efficient gene transfer into hematopoietic stem cells can be accomplished by stimulating the cells to divide in vitro or by developing new vector systems that can isolate transduced cells or that can deliver genes permanently into nondividing target cells. This review will discuss the progress and problems of these approaches in developing effective gene therapy for hematopoietic cells.

DNA Viruses↗
PubMed1997

The relationships between EMG and muscle morphology throughout sustained static knee extension at two submaximal force levels.

This study investigated the relationship between muscle morphology and surface electromyographic parameters (mean frequency, f(mean); and signal amplitude, RMS) during sustained static knee extension to exhaustion at 25% maximal voluntary contraction (MVC) and at 70% MVC. Twenty clinically healthy subjects participated. EMGs were registered from the quadriceps. Muscle forces during knee extension at a 90 degree joint angle were maintained at the respective levels throughout the measurement periods. A biopsy was obtained of the vastus lateralis muscle. The total time to exhaustion was normalized for each subject. By means of regression analysis, the intercept (i) (i.e. the unfatigued state) and the regression coefficient (k) were determined for each EMG parameter. The endurance time increased with decreasing force level. A significantly higher perception of fatigue was found at 25% MVC than at 70% MVC. From principal component analyses it was concluded that RMS-k at 25% MVC mainly correlated with the type 2 muscle fibre proportions (%), and at 70% MVC mainly with the areas of type 2 muscle fibre. At 25% MVC, f(mean)-k correlated with the areas of type 2A, 2B and 2C fibres, and at 70% MVC negatively with the proportion of type 2B and to some extent with areas of type 2A, 2B and 2C fibres. f(mean)-i at 25% MVC correlated with fibre type proportions (%); f(mean)-i at 70% MVC correlated with the areas of type 2A, 2B and 2C. The present study indicates relationships between surface EMG and muscle morphology, which is contrary to presented models of the EMG.

Adult↗
PubMed1997

Differential responses in intramuscular pressure and EMG fatigue indicators during low- vs. high-level isometric contractions to fatigue.

This study investigated changes in intramuscular pressure (IMP) and surface electromyographic (EMG) parameters (mean frequency of the power spectrum, f(mean); and signal amplitude denoted as root mean square, RMS) during contractions to fatigue at 25 and 70% of maximal voluntary contraction (MVC). Parameters were recorded simultaneously from the vastus lateralis muscle during knee extension. A significant decrease in f(mean) occurred with time at both contraction levels; however, the rate of decline (slope) was greater at 70% MVC. RMS increased throughout the contractions at both levels, with the relative increase being significantly greater for 25% MVC. IMP increased during 25% MVC but did not change during the 70% MVC contraction. IMP at rest was significantly higher post-contractions than it was pre-contractions at 25% MVC (21.1 vs. 8.0 mmHg, P < 0.01) and 70% MVC (13.7 vs. 8.6 mmHg, P < 0.01). Consequently, post-contraction IMP was higher at 25% MVC than at 70% MVC (P < 0.01). IMP changes throughout the fatiguing contractions correlated negatively with f(mean) and positively with RMS at both MVC levels; however, these correlations were better at 25% MVC. The extent of intramuscular water accumulation is discussed as a major cause of the difference in IMP changes between 25% and 70% MVC. Significant differences in the rate of change for all parameters between high vs. low contraction levels may suggest a common mechanism governing changes in IMP and EMG fatigue indicators.

Adult↗
PubMed1997

Reported symptoms and clinical findings in a group of subjects with longstanding bruxing behaviour.

Signs and symptoms of craniomandibular dysfunction (CMD) and social medical history were reported in 29 subjects, aged 23-68 years, with longstanding (5 years or more) bruxing behaviour. The subjects were selected from answers to an advertisement in the local newspaper. The subjects presented many symptoms of a general character including somatic and psycho-social problems, sleep disorders (72%), and pain (86%). More than half of the subjects (55%) had symptoms every day. Frequent aches in the neck, back, throat or shoulders were reported by 69% and frequent headache by 48% of the subjects. The most common symptoms of CMD were pain in the face or jaws (48%), stiffness in the jaws in the morning (44%), temporomandibular joint (TMJ) sounds (34%) and fatigue in the jaws during chewing (38%) and the most common clinical signs were more than three muscles tender on palpation (76%), TMJ-sounds (55%) and tenderness of TMJ on lateral palpation (66%). There was a statistically significant correlation between frequent tooth clenching and headache, pain in the neck, back, throat or shoulders, sleep disorders and high scores of the clinical dysfunction index (Di). The frequent clenchers had higher score values than the 'non-clenchers' for pain in the face and the jaws; headache; pain in the neck, back, throat or shoulders and the clinical dysfunction index (Di). These findings indicate a causal relationship between frequent tooth clenching and signs and symptoms of CMD, including headache and pain in the neck, back, throat or shoulders and high pathogenicity for frequent clenching. However, the material in this study is small and some precaution must be taken prior to generalized conclusions. More studies are required, especially sleep laboratory investigations, which could perhaps give answers to some of the numerous questions in this unexplored field of odontology.

Adult↗
PubMed1997

Personality traits in a group of subjects with long-standing bruxing behaviour.

The personality pattern of 29 subjects, 10 men and 19 women, with a mean age of 37.7 years (range 23-68) was studied by means of a personality inventory (KSP) and compared with the personality traits of a 'normal population'. The bruxers had significantly higher scores in the somatic anxiety and muscular tension scales and lower scores in the socialization scale; that is, the bruxers were more anxiety-prone, had higher vulnerability for psychosomatic disorders and were less socialized. The frequent clenchers (once to twice a week) comprised a special subgroup within the material with higher values in the somatic anxiety, psychic anxiety and muscular tension scales. A strong correlation was found between high values in the muscular tension scale and headache; aching neck, back, throat or shoulders; tooth clenching; number of muscles tender at palpation and the clinical dysfunction index (Di). The results of this study indicate a possible aetiological relationship between personality, tooth clenching and craniomandibular dysfunction (CMD). However, the material was small and some precaution must be taken prior to generalization of the results. Studies on larger material are needed and especially more studies in sleep laboratories.

Adult↗