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Biomedical subjects

R Colak

Publications and source records attributed to R Colak.

9 recordsLinked to original sources
PubMed2006

A comparison between the effects of low (1 microg) and standard dose (250 microg) ACTH stimulation tests on adrenal cortex functions with Behçet's disease.

INTRODUCTION: Behçet's disease is a rare, chronic disorder. The cause of Behçet's disease is unknown. It is believed to be caused by an autoimmune reaction. As in other chronic autoimmune diseases, Behçet's disease may show a subclinical adrenal failure and some changes in cortisol levels. We aimed to evaluate adrenal gland function in Behçet's disease patients. MATERIAL AND METHOD: This study included 18 Behçet's disease patients and 15 healthy controls. Patient and control groups were administered i.v. 1 microg low dose test (LDT) and 250 microg standard dose test (SDT) adrenocorticotropic hormone (ACTH) stimulation test after 12 h of night fasting with an interval of 3-days and cortisol responses in the 0th, 30th and 60th minutes were evaluated. RESULTS: There was no statistically significant difference between basal cortisol values of Behçet's disease and control groups. Cortisol values in the 60th minute in LDT were significantly lower in Behçet's disease group than in the control group. In the peak cortisol responses to LDT, a significant decrease was found in Behçet's disease group. CONCLUSION: These findings suggest that hypothalamo-pituitary adrenal axis is partially suppressed in Behçet's disease.

Adrenal Cortex↗
PubMed2005

PATIKAweb: a Web interface for analyzing biological pathways through advanced querying and visualization.

Patikaweb provides a Web interface for retrieving and analyzing biological pathways in the Patika database, which contains data integrated from various prominent public pathway databases. It features a user-friendly interface, dynamic visualization and automated layout, advanced graph-theoretic queries for extracting biologically important phenomena, local persistence capability and exporting facilities to various pathway exchange formats.

Computer Graphics↗
PubMed2004

Effects of short-period exercise training and orlistat therapy on body composition and maximal power production capacity in obese patients.

We examined the effects of weight loss induced by diet-orlistat (DO) and diet-orlistat combined with exercise (DOE) on maximal work rate production (Wmax) capacity in obese patients. Total of 24 obese patients were involved in this study. Twelve of them were subjected to DO therapy only and the remaining 12 patients participated in a regular aerobic exercise-training program in addition to DO therapy (DOE). Each patient performed two incremental ramp exercise tests up to exhaustion using an electromagnetically-braked cycle ergometer: one at the onset and one at the end of the 4th week. DOE therapy caused a significant decrease in total body weight: 101.5+/-17.4 kg (basal) vs 96.3+/-17.3 kg (4 wk) associated with a significant decrease in body fat mass: 45.0+/-10.5 kg (basal) vs 40.9+/-9.8 kg (4 wk). DO therapy also resulted in a significant decrease of total body weight 94.9+/-14.9 kg (basal) vs 91.6+/-13.5 kg (4 wk) associated with small but significant decreases in body fat mass: 37.7+/-5.6 kg (basal) to 36.0+/-6.2 kg (4 wk). Weight reduction achieved during DO therapy was not associated with increased Wmax capacity: 106+/-32 W (basal) vs 106+/-33 W (4 wk), while DOE therapy resulted in a markedly increased Wmax capacity: 109+/-39 W (basal) vs 138+/-30 W (4 wk). DO therapy combined with aerobic exercise training resulted in a significant reduction of fat mass tissue and markedly improved the aerobic fitness and Wmax capacities of obese patients. Considering this improvement within such a short period, physicians should consider applying an aerobic exercise-training program to sedentary obese patients for improving their physical fitness and thereby reduce the negative outcomes of obesity.

Adolescent↗
PubMed2002

The value of low dose (1 microg) ACTH stimulation test in the investigation of non-classic adrenal hyperplasia due to 11beta-hydroxylase deficiency.

Non-classic congenital adrenal hyperplasia (NCAH) is a rare cause of hirsutism and it results from a defect in the biosynthetic pathway of cortisol and/or aldosterone. 250 microg ACTH test (SDT) is used in the diagnosis of this disease. Our aim was to investigate the responses of 11-deoxycortisol to 1microg ACTH (LDT) test in women with NCAH due to 11-beta hydroxylase (11- beta OH) deficiency and to compare them with the values obtained after SDT in the patients and in the control subjects. Eleven patients with NCAH due to 11- beta OH deficiency and 15 control subjects were involved in the study. The main complaint of the patients with NCAH was hirsutism and the diagnosis was made if the adrenal 11-deoxycortisol response to SDT exceed threefold the 95th percentile of controls. ACTH stimulation tests were carried out consecutively by using 250 microg and 1 microg intravenous ACTH as a bolus injection after an overnight fast, and blood samples were drawn at 0,30 and 60 min. Peak cortisol, 17-hydroxyprogesterone (17-OHP) and DHEAS responses were similar in LDT and SDT while 11-deoxycortisol responses to LDT (15.7 +/- 1.8 nmol/L) were significantly (p < 0.005) lower than the results obtained after SDT (76.3 +/- 21.4 nmol/L) in women with 11- beta OH deficiency. Peak cortisol and 17-OHP responses to LDT in patients and control subjects were similar. Peak 11-deoxycortisol responses to LDT were significantly (p < 0.05) higher in NCAH patients (15.7 +/- 1.8 nmol/L) than in the control subjects (6.5 +/- 0.8 nmol/L). However, in LDT, all patients had peak 11-deoxycortisol level lower than threefold the 95th percentile (25.8 nmol/L) of controls. This study represents the first demonstration that LDT gives similar cortisol but not 11-deoxycortisol responses to SDT in patients with 11- beta OH deficiency. This study also showed that LDT can not replace SDT in every clinical situation.

17-alpha-Hydroxyprogesterone↗
PubMed2001

A comparison between low-dose (1 microg), standard-dose (250 microg) ACTH stimulation tests and insulin tolerance test in the evaluation of hypothalamo-pituitary-adrenal axis in primary fibromyalgia syndrome.

OBJECTIVE: Primary fibromyalgia syndrome (PFS) is a nonarticular rheumatological syndrome characterized by disturbances in the hypothalamo-pituitary-adrenal (HPA) axis. The site of the defect in the HPA axis is a matter of debate. Our aim was to evaluate the HPA axis by the insulin-tolerance test (ITT), standard dose (250 microg) ACTH test (SDT) and low dose (1 microg) ACTH test (LDT) in patients with PFS. DESIGN AND PATIENTS: Sixteen patients (13 female, three male) with PFS were included in the study. Sixteen healthy subjects (12 female, four male) served as matched controls. ACTH stimulation tests were carried out by using 1 microg and 250 microg intravenous (i.v.) ACTH as a bolus injection after an overnight fast, and blood samples were drawn at 0, 30 and 60 min. The ITT was performed by using i.v. soluble insulin, and serum glucose and cortisol levels were measured before and after 30, 60, 90 and 120 min. The 1 microg and 250 microg ACTH stimulation tests and the ITT were performed consecutively. RESULTS: Peak cortisol responses to both the low dose test (LDT) and standard dose test (SDT) (589 +/- 100 nmol/l; 777 +/- 119 nmol/l, respectively) were lower in the PFS group than in the control group (1001 +/- 370 nmol/l; 1205 +/- 386 nmol/l, respectively) (P < 0.0001). Peak cortisol responses to ITT (730 +/- 81 nmol/l) in the PFS group were lower than in the control group (1219 +/- 412 nmol/l) (P < 0.0001). Six of the 16 patients with PFS had peak cortisol responses to LDT lower than the lowest peak cortisol response of 555 nmol/l obtained in healthy subjects after LDT. There was a significant difference between the peak cortisol responses to LDT (589 +/- 100 nmol/l) and peak cortisol responses to ITT (730 +/- 81 nmol/l) in the PFS group (P < 0.0001). Peak cortisol responses to SDT (777 +/- 119 nmol/l) were similar to peak cortisol responses to ITT (730 +/- 81 nmol/l) in the PFS group. CONCLUSION: We conclude that the perturbation of the HPA axis in PFS is characterized by underactivation of the HPA axis. Some patients with PFS may have subnormal adrenocortical function. LDT is more sensitive than SDT or ITT in the investigation of the HPA axis to determine the subnormal adrenocortical function in patients with PFS.

Adrenocorticotropic Hormone↗
PubMed2000

A comparison between the 1-microg adrenocorticotropin (ACTH) test, the short ACTH (250 microg) test, and the insulin tolerance test in the assessment of hypothalamo-pituitary-adrenal axis immediately after pituitary surgery.

The short ACTH stimulation test is an easy, reliable, and extensively used test in the assessment of the hypothalamo-pituitary-adrenal (HPA) axis. However, its use immediately after pituitary surgery is a matter of debate. The insulin tolerance test (ITT) is the gold standard in the evaluation of the HPA axis, but it is not always without side effects and may be unpleasant early after pituitary surgery. Our aim was to investigate the value of the 1-microg ACTH test in the assessment of the HPA axis early after pituitary surgery. We also aimed to determine the value of the 1-microg and 250-microg ACTH tests and the ITT in the estimation of HPA axis status after 3 months postoperatively. Nineteen patients subjected to pituitary tumor surgery were included in the study, and the ITT and the 1-microg and 250-microg ACTH tests were performed between the 4th and 11th days of surgery. The tests were repeated at the first month in 3 patients with subnormal peak cortisol responses (454, 125, and 301 nmol/L) and in 18 patients at the third month postoperatively. ACTH stimulation tests were performed by using 1 microg and 250 microg ACTH iv as a bolus injection, and blood samples were drawn at 0, 30, and 60 min for measurement of serum cortisol levels. The ITT was performed by using iv regular insulin, and serum glucose and cortisol levels were measured. The 1-microg and 250-microg ACTH stimulation tests and the ITT were performed consecutively. At least 48 h were allowed between each test. A peak serum cortisol level of 550 nmol/L or greater was considered as a normal response for both the ITT and the ACTH tests. The serum cortisol level was measured by RIA using commercial kits. Serum glucose was determined by glucose oxidase method. There were correlations between the peak cortisol response to the ITT and the 1-microg ACTH test (r = 0.39, P < 0.05) in the early postoperative period. No correlation was found between the ITT and the 250-microg ACTH test responses. In the early postoperative period, two patients showed normal cortisol responses (> or =550 nmol/L) to the 1-microg ACTH test and five patients showed normal cortisol responses to the 250-microg ACTH test among the six patients with subnormal cortisol responses to the ITT. Three patients with subnormal cortisol responses to ITT and baseline cortisol values less than 240 nmol/L showed normal HPA axis at the end of the first month. In the late postoperative period, at the third month, all the patients showed normal HPA axis. In the early postoperative period of pituitary surgery, the 1-microg ACTH test results are more concordant than the 250-microg ACTH test in comparison with the ITT. Our results also indicate that HPA axis dysfunction shown by ACTH stimulation tests and the ITT in early postoperative period may be normalized 1-3 months after surgery. For this reason, we think that dynamic tests including the ITT may not be useful early after pituitary surgery.

Adrenocorticotropic Hormone↗
PubMed1999

Pituitary apoplexy probably due to TRH and GnRH stimulation tests in a patient with acromegaly.

Pituitary apoplexy is the most serious and life-threatening complication of pituitary adenomas. Most of the cases occur spontaneously but it may occur also after a number of events such as the pituitary stimulation tests. We report a case of acromegaly due to a giant pituitary adenoma in which pituitary apoplexy developed 88 hours after TRH/GnRH stimulation test. The patient had severe headaches, nausea, vomiting, visual disturbance and mental alteration and the computed tomography (CT) scans revealed intratumoral and intraventricular bleeding. The pituitary mass was removed by transsphenoidal approach. The patient developed pneumonia and died on the 9th postoperative day. Pituitary apoplexy was confirmed at surgery and on histological examination. Immunohistochemical staining was positive for GH and PRL. This case indicates that pituitary apoplexy may develop several days after TRH/GnRH stimulation test.

Acromegaly↗