Ann-Charlotte B. Svensson Holm

Cortisol in Saliva - Reference Ranges and Relation to Cortisol in Serum

The aim of this study was to establish morning and evening reference ranges for cortisol in saliva. Another objective was to compare the concentrations of the mainly free cortisol in saliva to those of total cortisol in serum as determined with a commercial radioimmunoassay. The concentrations were determined in matched samples of saliva and serum collected at 8 am and 10 pm from 197 healthy volunteers. The saliva samples were stable for at least 7 days at room temperature and for 9 months at -20 degrees C. Reference ranges, the central 95%, were estimated to 3.5-27.0 nmol/l at 8 am and < 6.0 nmol/l at 10 pm. The intra-assay coefficient of variation (CV) was below 5% and total CV below 10%. The relation between the cortisol concentrations in serum and saliva was non-linear with r = 0.86 for serum concentrations < 450 nmol/l and r = 0.44 for serum concentrations > or = 450 nmol/l. In conclusion, the satisfactory precision of the analysis and the simple non-invasive sampling procedure suggest that saliva may be used for cortisol measurements in situations where blood sampling is difficult to perform.

Salivary Cortisol - an Alternative to Serum Cortisol Determinations in Dynamic Function Tests

Abstract Salivary cortisol was measured as an alternative to serum cortisol as a marker for adrenocortical function following insulin tolerance test, corticotropin-releasing-hormone stimulation and adreno-corticotrophic hormone stimulation. During insulin tolerance test and corticotropin-releasing-hormone stimulation adreno-corticotrophic hormone was also measured. The tests were performed on healthy control subjects as well as on patients under investigation for various disturbances in the hypothalamic-pituitary-adrenocortical axis (insulin tolerance test: 3 controls on two occasions and 14 patients; corticotropin-releasing-hormone stimulation: 4 controls and 18 patients; adreno-corticotrophic hormone stimulation: 6 controls and 10 patients). Five patients underwent both insulin tolerance test and corticotropin-releasing-hormone stimulation. Using criteria for adequate cortisol response in serum, the patients were classified as good or poor responders. In 42 of the 45 tests performed the same conclusion as to cortisol status was drawn when based on serum and salivary cortisol responses. In healthy subjects and good responders the mean cortisol relative increase was greater in saliva than in serum in all three tests (p < 0.05). Characteristic of the results for the insulin tolerance test was a significant initial mean decrease (p < 0.05), not found in serum, and the highest observed salivary cortisol value was delayed for at least 30 minutes compared to that in serum. Plasma adreno-corticotrophic hormone correlated significantly with the cortisol concentrations determined 15 minutes later in serum (r = 0.54–0.64) and in saliva (r = 0.76–0.85). The more pronounced cortisol response in saliva than in serum and its closer correlation with adreno-corticotrophic hormone offer advantages over serum cortisol, suggesting salivary cortisol measurement may be used as an alternative parameter in dynamic endocrine tets.

Salivary cortisol and serum prolactin in relation to stress rating scales in a group of rescue workers

BACKGROUND Rescue service personnel are often exposed to traumatic events as part of their occupation, and higher prevalence rates of psychiatric illness have been found among this group. METHODS In 65 rescue workers, salivary cortisol at 8 AM and 10 PM and serum prolactin at 8 AM were related to the psychiatric self-rating scale General Health Questionnaire (GHQ-28) measuring psychiatric health, and the Impact of Events Scale (IES) and Post Traumatic Symptom Scale (PTSS) measuring posttraumatic symptoms. RESULTS Seventeen percent of the study population scored above the GHQ-28 cut-off limit but none scored beyond the cut-off limit in the IES and PTSS questionnaires. Salivary cortisol concentration at 10 PM correlated with statistical significance to anxiety (p < .005) and depressive symptoms (p < .01) measured with GHQ-28, as well as to posttraumatic symptoms, with avoidance behavior measured with IES (p < .01) and PTSS (p < .005). Two of the rescue workers were followed over time with the same sampling procedure after a major rescue commission. CONCLUSIONS The correlation between evening salivary cortisol and anxiety, depressiveness, and posttraumatic avoidance symptoms indicates that these parameters can be used in screening and follow-up after traumatic stress events.

Platelets stimulate airway smooth muscle cell proliferation through mechanisms involving 5-lipoxygenase and reactive oxygen species

Continuous recruitment and inappropriate activity of platelets in the airways may contribute to airway remodeling, a characteristic feature of inflammatory airway diseases that includes increased proliferation of the smooth muscle. The aim of the present investigation was to examine the effect of platelets on proliferation of airway smooth muscle cells (ASMC) in culture and to determine the possible role of 5-lipoxygenase (5-LOX) and reactive oxygen species (ROS) in this context. ASMC obtained from guinea pigs were cultured and co-incubated with washed platelets for 24 hours. Thereafter, the proliferation was measured with the MTS-assay; the results were also verified by using thymidine incorporation, DNA measurements and manual counting. The interaction between platelets and ASMC was visualized with fluorescence microscopy. We found that platelets bind to the ASMC and the presence of platelets caused a significant dose-dependent increase in ASMC proliferation. Co-incubation of ASMC with platelets also increased ROS-production, detected by the fluorescent probe DCFDA. Furthermore, the platelet-induced proliferation was reduced in the presence of the NADPH-oxidase inhibitors DPI and apocynin. A possible role of 5-LOX in platelet-induced proliferation and ROS-generation was evaluated by using the 5-LOX inhibitor AA-861 and the PLA2-inhibitor ATK. The results showed that inhibition of these enzymes significantly reduced the platelet-induced proliferation. Moreover, Western blot analysis revealed that the ASMC but not the platelets express 5-LOX. In addition, our experiments revealed that the presence of AA-861 and ATK significantly inhibited the ROS-production generated upon co-incubation of platelets and ASMC. In conclusion, we show that platelets have a marked capacity to induce ASMC proliferation. Furthermore, our study indicates that the interaction between platelets and ASMC leads to activation of 5-LOX in the ASMC followed by an increased ROS-production, events resulting in enhanced ASMC proliferation. The new findings are of importance in understanding possible mechanisms contributing to airway remodeling.

Platelet membranes induce airway smooth muscle cell proliferation

The role of platelets in airway disease is poorly understood although they have been suggested to influence on proliferation of airway smooth muscle cells (ASMC). Platelets have been found localized in the airways in autopsy material from asthmatic patients and have been implicated in airway remodeling. The aim of the present study was to investigate the effects of various platelet fractions on proliferation of ASMC obtained from guinea pigs (GP-ASMC) and humans (H-ASMC). Proliferation of ASMC was measured by the MTS assay and the results confirmed by measurements of the DNA content. A key observation was that the platelet membrane preparations induced a significant increase in the proliferation of both GP-ASMC (129.9 ± 3.0 %) and H-ASMC (144.8 ± 12.2). However, neither supernatants from lysed or filtrated thrombin stimulated platelets induced ASMC proliferation to the same extent as the membrane preparation. We have previously shown that platelet-induced proliferation is dependent on 5-lipoxygenase (5-LOX) and reactive oxygen species (ROS) pathways. In the present work we established that platelet membrane-induced ASMC proliferation was reduced in the presence of the NADPH oxidase inhibitor DPI and the 5-LOX inhibitor AA-861. In conclusion, our results showed that platelet membranes significantly induced ASMC proliferation, demonstrating that the mitogenic effect of platelets and platelet membranes on ASMC is mainly due to membrane-associated factors. The effects of platelet membranes were evident on both GP-ASMC and H-ASMC and involved 5-LOX and ROS. These new findings are of importance in understanding the mechanisms contributing to airway remodeling and may contribute to the development of new pharmacological tools in the treatment of inflammatory airway diseases.

Inhibition of 12-lipoxygenase reduces platelet activation and prevents their mitogenic function

Abstract The aim of the present study was to investigate the role of 12-lipoxygenase (12-LOX) on platelet-induced airway smooth muscle cell (ASMC) proliferation. Co-incubation of platelets and ASMC caused platelet activation as determined by morphological changes. Simultaneously, reactive oxygen species (ROS)-generation was detected and ASMC proliferation (measured by using the MTS assay) increased significantly. Furthermore, we found that the 12-LOX inhibitors cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC) and Baicalein prevented platelet activation in a co-cultures of platelets and ASMC. The inhibitory effect of CDC and Baicalein on platelets was also registered in a pure platelet preparation. Specifically, the 12-LOX inhibitors reduced collagen-induced platelet aggregation both in the presence and absence of external added fibrinogen. Importantly, platelet-induced ASMC proliferation and ROS production generated during the platelet/ASMC interaction was significantly inhibited in the presence of 12-LOX inhibitors. In conclusion, our findings reveal that 12-LOX is crucial for the observed enhancement of ASMC proliferation in co-cultures of platelets and ASMC. The present result suggests that 12-LOX activity is important in the initial step of platelet/ASMC interaction and platelet activation. Such action of 12-LOX represents a potential important mechanism that may contribute to platelet-induced airway remodelling.

Thrombin-induced lysosomal exocytosis in human platelets is dependent on secondary activation by ADP and regulated by endothelial-derived substances

Abstract Exocytosis of lysosomal contents from platelets has been speculated to participate in clearance of thrombi and vessel wall remodelling. The mechanisms that regulate lysosomal exocytosis in platelets are, however, still unclear. The aim of this study was to identify the pathways underlying platelet lysosomal secretion and elucidate how this process is controlled by platelet inhibitors. We found that high concentrations of thrombin induced partial lysosomal exocytosis as assessed by analysis of the activity of released N-acetyl-β-glucosaminidase (NAG) and by identifying the fraction of platelets exposing the lysosomal-associated membrane protein (LAMP)-1 on the cell surface by flow cytometry. Stimulation of thrombin receptors PAR1 or PAR4 with specific peptides was equally effective in inducing LAMP-1 surface expression. Notably, lysosomal exocytosis in response to thrombin was significantly reduced if the secondary activation by ADP was inhibited by the P2Y12 antagonist cangrelor, while inhibition of thromboxane A2 formation by treatment with acetylsalicylic acid was of minor importance in this regard. Moreover, the NO-releasing drug S-nitroso-N-acetyl penicillamine (SNAP) or the cyclic AMP-elevating eicosanoid prostaglandin I2 (PGI2) significantly suppressed lysosomal exocytosis. We conclude that platelet inhibitors that mimic functional endothelium such as PGI2 or NO efficiently counteract lysosomal exocytosis. Furthermore, we suggest that secondary release of ADP and concomitant signaling via PAR1/4- and P2Y12 receptors is important for efficient platelet lysosomal exocytosis by thrombin.

Active transport of L-tri-iodothyronine through the red cell plasma membrane--true or false?

The membrane transport of L-tri-iodothyronine has been studied in human erythrocyte ghosts. Initial uptake showed saturability with a Km of 33.8 nmol/l, suggesting carrier-mediated transport. Ouabain partly inhibited this uptake. ATP, on the other hand, caused a significant increase in the Vmax indicating an active transport of L-tri-iodothyronine across the erythrocyte plasma membrane. Ghosts from patients with hyperthyroidism, hypothyroidism or thyroid hormone resistance did not differ significantly from controls in their uptake of the hormone.

Thyroid hormone does not induce maturation of embryonic chicken cardiomyocytes in vitro

Fetal cardiac growth in mammalian models occurs primarily by cell proliferation (hyperplasia). However, most cardiomyocytes lose the ability to proliferate close to term and heart growth continues by increasing cell size (hypertrophy). In mammals, the thyroid hormone triiodothyronine (T3) is an important driver of this process. Chicken cardiomyocytes, however, keep their proliferating ability long after hatching but little information is available on the mechanisms controlling cell growth and myocyte maturation in the chicken heart. Our aim was to study the role of T3 on proliferation and differentiation of embryonic chicken cardiomyocytes (ECCM), enzymatically isolated from 19‐day‐old embryos and to compare the effects to those of insulin‐like growth factor‐1 (IGF‐1) and phenylephrine (PE). Hyperplasia was measured using a proliferation assay (MTS) and hypertrophy/multinucleation was analyzed morphologically by phalloidin staining of F‐actin and nuclear staining with DAPI. We show that IGF‐1 induces a significant increase in ECCM proliferation (30%) which is absent with T3 and PE. PE induced both hypertrophy (61%) and multinucleation (41%) but IGF‐1 or T3 did not. In conclusion, we show that T3 does not induce maturation or proliferation of cardiomyocytes, while IGF‐1 induces cardiomyocyte proliferation and PE induces maturation of cardiomyocytes.

Hyaluronic acid influence on platelet-induced airway smooth muscle cell proliferation

Hyaluronic acid (HA) is one of the main components of the extracellular matrix (ECM) and is expressed throughout the body including the lung and mostly in areas surrounding proliferating and migrating cells. Furthermore, platelets have been implicated as important players in the airway remodelling process, e.g. due to their ability to induce airway smooth muscle cell (ASMC) proliferation. The aim of the present study was to investigate the role of HA, the HA-binding surface receptor CD44 and focal adhesion kinase (FAK) in platelet-induced ASMC proliferation. Proliferation of ASMC was measured using the MTS-assay, and we found that the CD44 blocking antibody and the HA synthase inhibitor 4-Methylumbelliferone (4-MU) significantly inhibited platelet-induced ASMC proliferation. The interaction between ASMC and platelets was studied by fluorescent staining of F-actin. In addition, the ability of ASMC to synthesise HA was investigated by fluorescent staining using biotinylated HA-binding protein and a streptavidin conjugate. We observed that ASMC produced HA and that a CD44 blocking antibody and 4-MU significantly inhibited platelet binding to the area surrounding the ASMC. Furthermore, the FAK-inhibitor PF 573228 inhibited platelet-induced ASMC proliferation. Co-culture of ASMC and platelets also resulted in increased phosphorylation of FAK as detected by Western blot analysis. In addition, 4-MU significantly inhibited the increased FAK-phosphorylation. In conclusion, our findings demonstrate that ECM has the ability to influence platelet-induced ASMC proliferation. Specifically, we propose that HA produced by ASMC is recognised by platelet CD44. The platelet/HA interaction is followed by FAK activation and increased proliferation of co-cultured ASMC. We also suggest that the mitogenic effect of platelets represents a potential important and novel mechanism that may contribute to airway remodelling.