Biomedical subjects

Onno E Janssen

Publications and source records attributed to Onno E Janssen.

28 records · Page 2Linked to original sources

PubMed2004

Neuroendocrine response to casino gambling in problem gamblers.

Problematic gambling is thought to be influenced by neurobiological mechanisms. However, the neuroendocrine response to gambling is largely unknown. Therefore, the effect of casino gambling on the sympathoadrenal system, the HPA-axis, and pituitary hormones were analyzed. Fourteen male problem gamblers and 15 non-problem gamblers were examined in a balanced cross-over design. In the experimental session, participants played blackjack in a casino wagering their own money. During the control session, subjects played cards for accumulation of points. Heart rate and endocrine measures were recorded at baseline, at 30, 60 and 90 min during gambling/card playing, and after the game. Heart rate and norepinephrine levels increased with the onset of blackjack in both groups, with problem gamblers showing significantly higher levels across the entire gambling session. In addition, dopamine levels were significantly higher in problem gamblers during casino gambling compared to non-problem gamblers. Cortisol levels were transiently increased with the onset of blackjack in both groups. Casino gambling as a "real life" situation induces activation of the HPA-axis and the sympathoadrenergic system, with significantly more pronounced changes in problem gamblers. These findings may contribute to a better understanding of neuroendocrine disturbances in problem gambling.

Adrenocorticotropic Hormone↗

PubMed2004

Partial deficiency of thyroxine-binding globulin-Allentown is due to a mutation in the signal peptide.

We present an unusual variant of T(4)-binding globulin (TBG) found in a family from Allentown, Pennsylvania (TBG-AT). The heterozygous proposita presented serum total T(4) and TBG levels ranging from low to normal. TBG gene sequencing revealed a C-to-T substitution in codon -2 (CAC to TAC) leading to the substitution of the normal histidine by a tyrosine within the signal peptide. No mutation within the mature peptide was found. Allele-specific PCR confirmed the H(-2)Y mutation in the propositas mother and son. T(4)-binding analysis of TBG in serum from the proposita and son showed normal affinity but reduced capacity when compared with the unaffected father. Heat stability and isoelectric focusing of TBG-AT were normal. In vitro expression of a recombinant TBG-AT in Xenopus oocytes revealed a diminished secretory efficiency and confirmed the normal binding affinity and heat stability of the small amount of secreted TBG-AT. This study has defined impaired cotranslational processing as a hitherto unrecognized cause of hereditary TBG deficiency.

Adolescent↗

PubMed2004

High prevalence of autoimmune thyroiditis in patients with polycystic ovary syndrome.

OBJECTIVE: To investigate the prevalence of autoimmune thyroiditis (AIT) in patients with polycystic ovary syndrome (PCOS). DESIGN: Over a period of 30 months, 175 patients with PCOS were recruited to a prospective multicenter study to evaluate thyroid function and morphology; 168 age-matched women without PCOS were studied as a control group. METHODS: PCOS was defined as a- or oligomenorrhea, hyperandrogenism and exclusion of other disturbances of estrogen or androgen synthesis. All laboratory parameters were determined with automated immunoassays. Thyroid morphology was assessed by ultrasound. RESULTS: PCOS patients were characterized by an increased LH/FSH ratio, low progesterone, elevated testosterone and a high prevalence of hirsutism (PCOS 83%, control 3%; mean hirsutism score 12+/-5 and 3+/-2 respectively), but no differences in estrogen levels were found. Thyroid function and thyroid-specific antibody tests revealed elevated thyroperoxidase (TPO) or thyroglobulin (TG) antibodies in 14 of 168 controls (8.3%), and in 47 of 175 patients with PCOS (26.9%; P<0.001). On thyroid ultrasound, 42.3% of PCOS patients, but only 6.5% of the controls (P<0.001) had a hypoechoic tissue typical of AIT; while thyroid hormone levels were normal in all subjects, PCOS patients had a higher mean TSH level (P<0.001) and a higher incidence of TSH levels above the upper limit of normal (PCOS 10.9%, controls 1.8%; P<0.001). CONCLUSION: This prospective study demonstrates a threefold higher prevalence of AIT in patients with PCOS, correlated in part with an increased estrogen-to-progesterone ratio and characterized by early manifestation of the disease.

Adult↗

PubMed2003

Acute neuroendocrine response to sexual stimulation in sexual offenders.

BACKGROUND: Several pharmacotherapeutic approaches have confirmed the influence of neuroendocrine parameters on sexual desire, function, and fantasies in men; however, the relevance of acute neuroendocrine changes in mediating heightened sexual drive remains unknown. We recently demonstrated that plasma prolactin substantially increases following orgasm in healthy men, suggesting a feedback mechanism for peripheral prolactin in the control of acute sexual arousal. Because prolactin appears to play a regulatory role in acute sexual drive, we initiated this study to see whether sexual offenders with a high sexual drive have a different neuroendocrine response to sexual arousal. This study compares the prolactin response to orgasm of sexual offenders with high sexual drive and that of healthy subjects with average sexual drive. METHODS: From a subject pool of 150 inpatients held because of sexual crimes, we recruited 10 volunteers, based on their high sexual drive according to an intensive, semistructured clinical interview. We defined sexual drive by a short refractory period and strong sexualization, or a high frequency of sexual stimulation. We analyzed the acute psychoneuroendocrine response to sexual arousal and orgasm continuously before, during, and after masturbation-induced orgasm in patients and control subjects. RESULTS: Sexual offenders demonstrated higher sexual desire (P < 0.001) and function (P < 0.001) and a more positively perceived refractory period (P < 0.05). Both groups displayed a prolonged, significant increase in prolactin plasma levels after orgasm (P < 0.001). Sexual offenders did not differ from control subjects in neuroendocrine response to sexual arousal and orgasm. CONCLUSIONS: These data demonstrate that sexual offenders with a high sexual drive do not differ from control subjects in the postorgasmic neuroendocrine response, particularly in prolactin release. This study confirms that factors other than peripheral hormones influence deviant sexual behaviour.

Adult↗

PubMed2003

Quality of life, psychosocial well-being, and sexual satisfaction in women with polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by chronic anovulation and hyperandrogenism. PCOS is one of the leading causes of infertility and manifests with hirsutism, acne, and obesity. To investigate its impact on health-related quality of life and sexuality, 50 women with PCOS and 50 controls were evaluated with standardized questionnaires (36-item short-form health survey, symptom checklist revised, and life satisfaction questionnaire). The impact of hirsutism, obesity, and infertility was assessed using five-point rating scales, and sexual satisfaction was analyzed with visual analog scales. Patients showed greater psychological disturbances on the symptom checklist revised dimensions, obsessive-compulsive, interpersonal sensitivity, depression, anxiety, aggression, and psychoticism, along with a lower degree of life satisfaction in the life satisfaction questionnaire scales health, self, and sex. Health-related quality of life measured with the 36-item short-form health survey revealed significantly decreased scores for physical role function, bodily pain, vitality, social function, emotional role function, and mental health in patients with PCOS. Although patients had the same partner status and frequency of sexual intercourse, they were significantly less satisfied with their sex life and found themselves less attractive. Most of the differences were not affected by correction for body weight. In conclusion, PCOS causes a major reduction in the quality of life and severely limits sexual satisfaction.

Adult↗

PubMed2002

Loop variants of the serpin thyroxine-binding globulin: implications for hormone release upon limited proteolysis.

Thyroxine-binding globulin (TBG) and corticosteroid-binding globulin are unique among non-inhibitory members of the superfamily of serine-proteinase inhibitors (serpins) in undergoing a dramatic increase in stability [stressed-to-relaxed (S-->R) transition] after proteolytic cleavage within their exposed reactive-site-loop (RSL) equivalent. This structural rearrangement involves the insertion of the cleaved loop as a new strand into the beta-sheet A and is accompanied by a decrease in hormone binding. To define the mechanism that leads to disruption of hormone binding of TBG after proteolytic cleavage, the effect of partial loop deletions and replacements by the alpha(1)-proteinase inhibitor homologues of TBG were evaluated. Unexpectedly, deletion of the loop's C-terminus, thought to be important for thyroxine binding, improved the binding affinity over that of normal TBG. Proteolytic cleavage of this variant revealed an intact S-->R transition and reduced its binding activity to that of cleaved TBG. In contrast, a chimaera with C-terminal loop extension mimicked the decreased binding affinity of cleaved TBG and had a thermal stability intermediate between that of native and cleaved serpins. This variant was still susceptible to loop cleavage and underwent an S-->R transition, yet without changing its binding affinity. Our data exclude a direct involvement of loop residues in thyroxine binding of native TBG. Limited insertion of the RSL into beta-sheet A appears to trigger hormone release after proteolytic cleavage. In support of this concept, residues within the hinge region of the TBG loop are phylogenetically highly conserved, suggestive of their physiological role as a functional switch in vivo.

Amino Acid Sequence↗

PubMed2002

Endoscopic treatment of solitary, bilateral, multiple, and recurrent pheochromocytomas and paragangliomas.

Because of extensive intraoperative catecholamine release, extreme vascularization, and demanding localization, laparoscopic and retroperitoneoscopic excision of pheochromocytomas and retroperitoneal paragangliomas is challenging. In a prospective clinical study, 61 chromaffin neoplasms (52 pheochromocytomas, 9 paragangliomas) were removed endoscopically from 52 patients (30 males, 22 females; age 44.4 +/- 16.3 years) at 55 operations. Six patients showed multiple (two to five) tumors. Tumor size ranged from 1 to 7 cm (mean 3.6 +/- 1.4 cm). Twelve patients suffered from hereditary diseases. Seven patients had bilateral adrenal diseases; in three patients pheochromocytomas were removed on both sides synchronously. Four neoplasias were local recurrences (three pheochromocytomas, one paraganglioma). The laparoscopic route was chosen for six operations, and the retroperitoneoscopic technique was performed in 49 procedures. Partial adrenalectomy was performed in 19 operations (in all patients with bilateral diseases). High-dosage a-blockage with phenoxybenzamine was routinely used. There were no conversions to open surgery. Perioperative complications were minor (23%), and mortality was zero. The operating time for unilateral pheochromocytomas was 116 +/- 52 minutes (range 35-285 minutes) and depended on tumor size (<3 cm vs. > or = 3 cm; p <0.01), gender (p <0.01), and extent of resection (partial vs. complete; p <0.05). The operating time for bilateral pheochromocytomas ranged from 285 to 385 minutes, and it was 75 to 600 minutes for paragangliomas. Blood loss was 100 +/- 171 ml. Consumption of analgesics was low (mean 7 mg piritramide postoperatively). The median duration of postoperative hospitalization was 4 days. In six of seven patients with bilateral disease complete preservation of cortical function was achieved. Locoregional metastatic recurrence was found in one patient 3 years after retroperitoneoscopic adrenalectomy. Endoscopic removal of solitary, bilateral, multiple, and recurrent pheochromocytomas and retroperitoneal paragangliomas is feasible and safe but requires extensive experience in minimally invasive and endocrine surgery.

Adolescent↗

PubMed2002

Characterization and primary structures of bovine and porcine thyroxine-binding globulin.

Thyroxine-binding globulin (TBG) is the major serum transport protein for iodothyronines in most of the large, omni- or herbivorous mammals. Characterization of human TBG (hTBG), including its 20 known natural variants, allowed the identification of the ligand-binding site and a correlation of diminished synthesis or loss of function with mutations in the TBG gene. Further refinement of the structure-function correlation, especially the high binding affinity and heat stability, requires characterization of other mammalian TBGs, of which only rat and sheep TBG were available. We now present some of the chemical and physical properties of bovine TBG (bTBG) and porcine TBG (pTBG) and their primary structures deduced from their cDNA sequences. The serum concentrations of bTBG and pTBG estimated by Scatchard analysis of T(4)-binding were similar to hTBG. The T(4)-binding affinity of human, bovine and porcine TBGs were all similar, at 1.2x10(10) M(-1). However, heat stability of the animal TBGs was reduced, with a half life of denaturation of 7 min (bTBG) and 5 min (pTBG) at 55 degreeC, compared with 21 min for hTBG. Nucleotide alignment revealed identity with hTBG of 85.5% (bTBG) and 83.7% (pTBG) and amino acid identity of 82.8% (bTBG) and 82.6% (pTBG). As expected, the relevant parts of the ligand-binding domain (amino acids 215-291, and 363-395) were highly conserved at more than 95% similarity. Comparison of the five known mammalian TBGs allows focusing of future mutagenesis experiments to further characterize the properties of the molecule.

Amino Acid Sequence↗

PubMed2002

Characterization of T(4)-binding globulin cleaved by human leukocyte elastase.

T(4)-binding globulin (TBG) serves to maintain an important serum pool of thyroid hormones and to prevent their excessive loss in urine. TBG has also been implicated in the tissue distribution and targeted delivery of the hormones, the mechanisms of which remain unclear. By virtue of sequence homology, TBG belongs to the serine proteinase inhibitors superfamily of proteins that are characterized by a reactive site loop serving as a recognition site for serine proteinases. However, both TBG and another serpin with hormone transport function, corticosteroid-binding globulin, are noninhibitory. Cleavage of corticosteroid-binding globulin by human leukocyte elastase results in the reduction of its hormone-binding affinity and capacity. In this communication we confirm previous observations that TBG is also cleaved by elastase and undergoes the characteristic conformational changes. In addition, contrary to a previous report, the present work demonstrates that the cleaved product has reduced T(4)-binding affinity and, as expected, increased heat stability. Additional fragmentation of the molecule results in the loss of the hormone-binding site that is in agreement with a recent in vivo observation of apparent consumption at sites of inflammation. These data suggest that TBG may play a role in the targeted delivery of thyroid hormones to tissues rich in proteinases.

Binding Sites↗

PubMed2002

Sensitive calcitonin measurement by two-site immunometric assays: implications for calcitonin screening in nodular thyroid disease.

The aim of this study was to investigate the impact of analytical aspects on the clinical usefulness of calcitonin (CT) measurement. In a retrospective analysis, CT levels measured by a polyclonal immunometric assay (Scantibodies Laboratory, CA, USA) were evaluated in various clinical situations. CT in newly diagnosed medullary thyroid cancer (MTC) (n = 20) ranged from 15.5-87130 pg/ml (median 661 pg/ml). Levels >10 pg/ml were seen in 7.3% of 314 patients with benign nodules, 48.9% of 45 patients with impaired kidney function, 97.7% of 87 patients on hemodialysis, 30.2% of 43 patients after renal transplantation, and in 71.0% of 31 patients with critical illnesses. Subgroups of patients were reevaluated by two monoclonal immunometric assays specific for mature CT. CT levels measured by the monoclonal immunometric assays were highly correlated to the polyclonal assay results in MTC patients, but were significantly different with a lower incidence of elevated levels in patients with renal disease and critical illnesses. In conclusion, highly sensitive assays with cut-off values of 10 pg/ml or below are mandatory for CT screening in nodular thyroid disease. The specificity of CT measurement in patients with renal disease and critical illnesses is higher with monoclonal assays specific for monomeric CT. These methodological aspects have to be regarded if CT measurement is used for decision making in nodular thyroid disease.

Adult↗