A sensitive direct enzyme immunoassay for cortisol in plasma and saliva

The effects of Chinese five-element music therapy on nursing students with depressed mood

This study aimed to evaluate the effects of Chinese five-element music therapy on nursing students with depressed mood. We randomly assigned 71 nursing students from Taiwan with depressed mood to the music and control groups. The music group (n = 31) received Chinese five-element music therapy, whereas the participants in the control group (n = 40) maintained their routine lifestyles with no music therapy. All of the participants were assessed using the Depression Mood Self-Report Inventory for Adolescence, and their salivary cortisol levels were measured. The study found that there was a significant reduction in depression between the pre- and posttherapy test scores and in salivary cortisol levels over time in the music group. After receiving the music therapy, the nursing students' depression levels were significantly reduced (P = 0.038) compared with the control group (P < 0.001). These results indicate that the Chinese five-element music therapy has the potential to reduce the level of depression in nursing students with depressed mood.

One-step monoclonal antibody based enzyme-linked immunosorbent assay for direct determination of cortisol in serum

Monoclonal antibodies to cortisol have obvious potential advantages as starting materials for assay systems to detect their levels in body fluids. This is very important for monitoring pituitary gland and adrenal functions. To develop a one-step competitive heterogeneous enzyme-linked immunosorbent assay (ELISA), a monoclonal anti-cortisol antibody was generated using a reasonably designed haptenic derivative. Cortisol-3-O-carboxymethyloxime was coupled to carrier protein bovine serum albumin (BSA) to enhance its immunogenicity. Spleen cells were prepared from a BALB/c mouse, which had repeatedly been immunized with a conjugate of cortisol-3-O-carboxymethyloxime-bovine serum albumin (cortisol-3-O-CMO-BSA), to be fused with SP2/0 myeloma cells. After one fusion experiment, four hybridoma clones secreting a practical antibody were established. One of the resulting monoclonal antibodies, 2C9D11B5, showed an affinity constant (Ka) of 1.4 × 10(10) M(-1) for cortisol and provided a practical calibration curve (limit of detection [LOD], 0.26 ng per assay) in this ELISA system employing cortisol-21-hemisuccinate-horseradish peroxidase (cortisol-21-HS-HRP) as a tracer. Cross-reactivities with related C-21 steroids were acceptably low: 11-deoxycortisol (3.5%), cortisone (0.47%), corticosterone (<0.01%), progesterone (<0.01%), 17-hydroxyprogesterone (1.2%), 6-hydroxycortisol (7.6%), and tetrahydrocortisol (<0.01%). The intra-assay and inter-assay coefficient of variations (CVs) ranged from 4.3% to 9.2% and 3.8% to 10.4 %, respectively. The analytical recoveries were 92.3% to 116.3%. Serum cortisol levels of healthy volunteers were determined after chilled acetone, stripped to be 292.76 ± 201.38 ng/mL (n=5), which are in the reference range.

Evaluation of a radioimmunoassay and establishment of a reference interval for salivary cortisol in healthy subjects in Denmark

A commercial radioimmunoassay (RA) for salivary cortisol was evaluated using certified reference material in water and spiked to pooled saliva in the range 2.1-89.1 nmol/L. A variance component model for describing the effects of age, body mass index (BMI), diurnal variation, gender, days of sick leave during the past year, and smoking habits was established. Reference intervals for salivary cortisol in 120 healthy individuals performing their routine work were established according to the International Union of Pure and Applied Chemistry (IUPAC) and the International Federation of Clinical Chemistry (IFCC). The method evaluation of the certified reference material in water did not show any bias of the method, i.e. recovery was 97% [CI: 94%; 100.9%]. LOD (detection limit) was 1.59 nmol/L. The ratio between analytical and within-subject variation (CVa/CVi) was 0.14, indicating that the method was adequate for measurement in healthy subjects. Reference intervals were estimated to be from 3.6 to 35.1 nmol/L for samples at the time of awakening (05.27-07.27), 7.6-39.4 nmol/L for peak level in saliva samples collected 20 min after awakening (05.47-07.47), and LOD 10.3 nmol/L for late afternoon samples (17.00-19.00). Reactivity (increase from awakening to 20 min after awakening) was estimated to be 82% [CI: -179; 345%] and recovery (decrease from 20 min after awakening to 18.00) to be 80% [CI: 51; 109%]. Eighteen percent of the subjects showed a decrease in cortisol in saliva from awakening to 20 min after awakening. Salivary cortisol was not affected by age, body mass index, gender, smoking habits or days of sick leave during the past year.

The diagnostic applications of saliva--a review

This review examines the diagnostic application of saliva for systemic diseases. As a diagnostic fluid, saliva offers distinctive advantages over serum because it can be collected non-invasively by individuals with modest training. Furthermore, saliva may provide a cost-effective approach for the screening of large populations. Gland-specific saliva can be used for diagnosis of pathology specific to one of the major salivary glands. Whole saliva, however, is most frequently used for diagnosis of systemic diseases, since it is readily collected and contains serum constituents. These constituents are derived from the local vasculature of the salivary glands and also reach the oral cavity via the flow of gingival fluid. Analysis of saliva may be useful for the diagnosis of hereditary disorders, autoimmune diseases, malignant and infectious diseases, and endocrine disorders, as well as in the assessment of therapeutic levels of drugs and the monitoring of illicit drug use.

One step enzyme linked immunosorbent assay for direct estimation of serum cortisol

One step competitive enzyme linked immunosorbent assay (ELISA) for direct estimation of cortisol in human serum is described. Cortisol-3-O-carboxymethyl-oxime-bovine serum albumin (cortisol-3-O-CMO-BSA) was used as an immunogen and cortisol-21-hemisuccinate-horse radish peroxidase (cortisol-21-HS-HRP) was used as a tracer. To the cortisol antibody coated microtiter wells, standards or serum samples (25 microl) along with cortisol-HRP conjugate (100 microl) were incubated for 2 hours at 37 degrees C. Bound enzyme activity was measured by, using TMB/H2O2 as a substrate. In this new strategy, chilled acetone stripped pooled human serum and sodium salicylate were used for preparing the standards and blocking the cortisol binding globulin (CBG), respectively. The sensitivity of the assay was .28 microg/100ml. The intraassay and interassay coefficient of variations (CVs) were ranged from 1.3% to 9.3% and 6.8% to 12.3 %, respectively. The analytical recoveries were 94% to 101.5%. The serum cortisol values, obtained by this method were correlated well with those, obtained by radioimmunoassay; r=0.95 (n=52).

Synthesis of a cortisol-biotin conjugate and evaluation as a tracer in an immunoassay for salivary cortisol measurement

Cortisol 3-(o-carboxymethyl)oxime (C3-CMO) and a commercially available biotin-hydrazide derivative were used to synthesize a C3-CMO-biotin conjugate. C3-CMO was converted into a N-hydroxysuccinimide ester derivative which in a second reaction step was allowed to interact with the hydrazide derivative of biotin. This simple-to-perform synthesis yielded a conjugate suitable for use as a tracer in immunoassays for cortisol measurement. Employing biotin as the primary probe in a competitive solid phase immunoassay allows for variable end point determination by means of commercially available labeled avidin or streptavidin derivatives. Streptavidin-Europium was used in conjunction with the DELFIA-system for time-resolved fluorometric end point measurement (TR-FIA) throughout the study. In addition, colorimetric end point determination (ELISA) using streptavidin-alkaline phosphatase as a secondary probe was established and evaluated. Both forms of this non-isotopic assay showed excellent correlation with a commercially available radioimmunoassay adapted for salivary cortisol measurement. The lower detection limit was 0.43 nM for a 50 microliters salivary sample. The intra-assay coefficient of variation was 6.7, 4.7 and 4.0% at cortisol concentrations of 2.2, 5.5 and 13.2 nM, respectively (n = 37), and the corresponding inter-assay coefficients of variation were 9.0, 8.6 and 7.1% (n = 50). The competitive immunoassay requires 1.5 h incubation time and shows robust and reproducible performance. The C3-CMO-biotin conjugate allows for sensitive and flexible end point determination of salivary cortisol levels in immunoassays.

Cortisol and beta-endorphin response in alcoholics and alcohol abusers following a high naloxone dosage

The course of plasma cortisol and beta-endorphin-like immunoreactivity (beta-EP-IR) was determined following a single i.v. administration of 20 mg naloxone. The test subjects included 20 male alcoholics (medication-free), investigated one to three days and four weeks after the onset of abstinence, as well as 10 short-time abstinent alcohol abusers and 10 healthy control subjects. The mean baseline values of cortisol and beta-EP-IR remained within normal limits in all groups. The significant decrease in the plasma cortisol baseline values in the alcoholics after 4 weeks abstinence may indicate a lower level of the regulation of the hypothalamic-pituitary-adrenal axis (HPA) under conditions of abstinence. After naloxone administration an increase in plasma cortisol and beta-EP-IR was observed in all groups. The multivariate trend analysis showed significant differences in the time course of plasma cortisol between the three groups, however not in the course of beta-EP-IR. The changes in the dynamic regulation of the HPA axis, resulting from chronic alcohol consumption, appears to be irrespective of whether the drinking pattern is dependent or abusive. In alcoholics these changes could still be identified following a 4-week abstinence period.

Stress-related changes of saliva cortisol in VDU operators

In the field of work physiology, catecholamines and cortisol are used as strain indicators, because their production is increased in stressing work situations. Short-term stress cannot be ascertained by measuring catecholamines in urine. We studied the excretion of cortisol in saliva during short-term stress. We examined 77 healthy subjects who worked at a video display unit (VDU) for 30 min. They had to carry out a task with high speed and accuracy demands. Saliva specimens were taken before and after VDU work. Saliva cortisol levels were determined by means of a sensitive enzyme immunoassay (EIA). Additionally physiological parameters (heart rate, blood pressure, respiratory rate) and task performance were measured, and the subjects were asked about their feelings of stress and psychovegetative disorders. Saliva cortisol concentrations were significantly increased after 30 min of VDU work. Heart rate, blood pressure and respiratory rate were also increased during the task. In persons with high heart rate and blood pressure levels saliva cortisol increased significantly stronger during VDU work than in persons with lower heart rate and blood pressure levels. The results indicate that saliva cortisol is a useful strain indicator in short-term stress situations.

Salivary corticosteroids in the study of adrenal function

Salivary corticosteroids (SCC) and plasma corticosteroids (PCC) were studied under basal conditions, after dexamethasone (DXM) and in the ACTH stimulation test in a reference group (RG) of 33 adults, in three groups with non-adrenal pathology and in a group of 4 patients with hypercortisolaemia. SCC and PCC were measured using a non-extraction RIA method using [3H]cortisol. The results for SCC in the RG and in the groups with non-adrenal pathology were similar to those obtained for PCC in terms of percentage of decrease in the circadian rhythm or DXM suppression. However, the responsiveness to ACTH in saliva was twice that obtained in plasma. In patients with hypercortisolism, SCC were in closer agreement with the adrenal hyperfunction than PCC. From the previous results the following conclusions may be drawn: (a) SCC differentiate adrenal gland normal function from hyperfunction as clearly or even better than PCC does; (b) SCC were in a closer agreement with the symptomatology of adrenal hyperfunction than were PCC; and (c) the responses to ACTH obtained with SCC were clearly higher than those obtained with PCC.

Enzyme immunoassay of cortisol in human plasma using penicillinase as label

An enzyme immunoassay for cortisol in human plasma using an antiserum raised against cortisol-3-O-carboxy-methyloxime bovine serum albumin and cortisol-21-hemisuccinate conjugated to penicillinase as tracer is described. Although employing immunoassay plates for separation of antigen-antibody complex from the free components was less time consuming, the slope and sensitivity of the standard curve were improved by the addition of goat anti-rabbit gamma globulin for precipitating the complex. There was good correlation between radioimmunoassay and enzyme immunoassay results obtained for cortisol levels present in normal human plasma.

Enzyme immunoassay of serum cortisol using a new transferable needle lid technique

A simple enzyme immunoassay of serum cortisol using for the first time a transferable needle lid as solid phase has been developed. The needles coated with second antibody and dipped into the wells of a microtitre plate bind the specific antibody of a competitive enzyme immunoassay mixture. Bound enzyme activity is estimated in the wells of another microtitre plate. This technique provides further advantages on the frequently used microtitre plate version. Washes between the immunological and the enzymatic reaction take very short time and are less laborious. Due to the facility of simultaneous starting and stopping of all reactions, a better precision and sensitivity is achieved. In the present cortisol assay, horseradish peroxidase covalently coupled to cortisol-21-hemisuccinate was used as enzyme label and tetramethylbenzidine as the chromogen for measuring enzyme activity. No extraction or deproteinization steps are involved. The turn around time for 41 samples (in duplicate) is 2.5 h. The detection limit of the assay is 5 pg of cortisol per well. Results of the present method correlated well (r = 0.92) with those of a commercial radioimmunoassay using iodinated cortisol.