Glucagonlike peptide-1 receptor: an example of translational research in insulinomas: a review

Glucagonlike peptide-1 receptors (GLP-1R) play an increasingly important role in endocrine gastrointestinal tumor management. In particular, virtually all benign insulinomas express GLP-1R in high density. Exendin-4 is a GLP-1 analog that has a longer half-life than GLP-1. Targeting GLP-1R by (111)In-DOTA-exendin-4 or (111)In-DPTA-exendin-4 offers a new approach that permits the successful localization of small benign insulinomas. It is likely that this new noninvasive technique has the potential to replace the invasive localization by selective arterial stimulation and venous sampling.

Circulating biomarkers in neuroendocrine tumors of the enteropancreatic tract: application to diagnosis, monitoring disease, and as prognostic indicators

Neuroendocrine tumors (NETs) are difficult to diagnose. Their symptoms may be vague or intermittent, and are frequently associated with much more common diseases; many of the tumors may be asymptomatic. Therefore, diagnosis can be delayed for some years. Because most NETs are secretory, the measurement of circulating biomarkers is helpful not only for diagnosis but also for assessing tumor response to treatment, monitoring disease progression, and use as prognostic indicators.

Rest-activity disturbances in children with septo-optic dysplasia characterized by actigraphy and 24-hour plasma melatonin profiles

INTRODUCTION

A trial of melatonin treatment in children with septo-optic dysplasia (SOD) and sleep disruption is accepted clinical practice in many centers. However, no objective measurements of sleep/activity patterns with 24-h melatonin profiles have been published for these individuals, and the pathophysiological basis underlying sleep disorders in SOD remains largely unknown.

METHODS

We studied six children with rest-activity disturbances and SOD. All wore an Actiwatch-Mini (a noninvasive method of detecting and recording movement intensity) for 2 wk and were admitted to hospital for a 24-h period during which hourly measurements of serum melatonin were taken. Sleep data were analyzed in conjunction with a detailed sleep diary. Ethical approval was obtained for these studies.

RESULTS

Two children produced virtually no melatonin throughout the 24-h period of measurement and had fragmented sleep patterns with no evidence of a non-24-h sleep-wake disorder or delayed sleep-phase disorder. One child had a normal melatonin profile despite actigraphy showing an arrhythmic sleep pattern. The remaining three children had fragmented sleep, with two having normal melatonin profiles and one having a modest increase in daytime melatonin concentrations, making the timing of dim-light melatonin onset difficult to discern.

CONCLUSIONS

There is considerable variation in timing and amount of melatonin secretion in these children. Surprisingly, none of the children had either actigraphic or melatonin profile evidence of a non-24-h sleep-wake disorder or delayed sleep-phase disorder. Understanding the heterogeneous nature of underlying sleep disorders in this group of children is important and has implications for their management.

Combined use of fasting plasma glucose and glycated hemoglobin A1c in the screening of diabetes and impaired glucose tolerance

The aim of this study is to assess the validity of combined use of fasting plasma glucose (FPG) and glycated hemoglobin A1c (HbA1c) as screening tests for diabetes and impaired glucose tolerance (IGT) in high-risk subjects. A total of 2,298 subjects were included. All subjects underwent a 75-g oral glucose tolerance test (OGTT) and HbA1c measurement. Receiver operating characteristic curve (ROC curve) analysis was used to examine the sensitivity and specificity of FPG and HbA1c for detecting diabetes and IGT, which was defined according to the 1999 World Health Organization (WHO) criteria. (1) Based on the ROC curve, the optimal cut point of FPG related to diabetes diagnosed by OGTT was 6.1 mmol/l that was associated with a sensitivity and specificity of 81.5 and 81.0%, respectively; The optimal cut point of HbA1c related to diabetes diagnosed by OGTT was 6.1%, which was associated with a sensitivity and specificity of 81.0 and 81.0%, respectively; The screening model using FPG > or = 6.1 mmol/l or HbA1c > or = 6.1% had sensitivity of 96.5% for detecting undiagnosed diabetes; the screening model using FPG > or = 6.1 mmol/l and HbA1c > or = 6.1% had specificity of 96.3% for detecting undiagnosed diabetes. (2) Based on the ROC curve, the optimal cut point of FPG related to IGT diagnosed by OGTT was 5.6 mmol/l that was associated with a sensitivity and specificity of 64.1 and 65.4%, respectively; The optimal cut point of HbA1c related to IGT diagnosed by OGTT was 5.6%, which was associated with a sensitivity and specificity of 66.2 and 51.0%, respectively; The screening model using FPG > or = 5.6 mmol/l or HbA1c > or = 5.6% had sensitivity of 87.9% for detecting undiagnosed IGT; The screening model using FPG > or = 5.6 mmol/l and HbA1c > or = 5.6% had specificity of 82.4% for detecting undiagnosed IGT. Compared with FPG or HbA1c alone, the simultaneous measurement of FPG and HbA1c (FPG and/or HbA1C) might be a more sensitive and specific screening tool for identifying high-risk individuals with diabetes and IGT at an early stage.

Does leptin predict incident hypertension in older adults?

OBJECTIVE

Leptin is associated with blood pressure (BP) in experimental and cross-sectional studies, but only one previous prospective study of middle-aged men has reported the association between leptin and incident hypertension. We examined the association of leptin levels with incident hypertension in a population-based study of older men and women.

DESIGN

Longitudinal cohort study.

POPULATION

Participants were 602 community-dwelling older adults with normal baseline BP levels who attended a research clinic visit between 1984 and 1987 and again 4.4 years later (mean age was 66.2 +/- 11.4; 60.6% were men; mean body mass index (BMI) 24.9 +/- 3.4 kg/m(2)).

MEASUREMENTS

Hypertension was defined as systolic BP > or =140 mmHg and/or diastolic BP > or =90 mmHg and/or antihypertensive drug treatment. Leptin was measured by radioimmunoassay.

RESULTS

After an average 4.4-year follow-up (minimum 2-maximum 7 years), 106 (17.6%) new cases of hypertension were identified. At baseline, participants who developed hypertension were older and had higher systolic BP and higher total cholesterol compared to participants who remained normotensive. Baseline serum leptin levels were higher in participants who developed hypertension compared to persistent normotensives [median (25th-75th range)] [8.8(5-16) vs 7(4-11) ng/ml, P = 0.002]. In logistic regression models, leptin (log-transformed) predicted incident hypertension before and after adjustments for baseline age, BMI, systolic BP, total cholesterol, medications, and previous cardiovascular disease (OR 1.75 95% CI 1.17-2.61, P = 0.006). This association persisted after exclusion of 45 obese participants.

CONCLUSION

Higher leptin levels were independently associated with increased odds of incident hypertension in older adults.

The diagnosis and treatment of growth hormone deficiency in adults

PURPOSE OF REVIEW

This review summarizes the recent published information regarding efficacy and complications of growth hormone replacement therapy. Several recent reports have monitored patients for periods of up to 10 years. Additionally, a consensus conference has been held regarding needed improvements in diagnostic testing and the recommendations of consensus panels regarding diagnostic criteria and laboratory test utilization are summarized.

RECENT FINDINGS

Long-term studies show growth hormone can be administered safely and that muscle strength and function as well as lipoprotein abnormalities and low-bone mineral density show sustained improvement over extended periods of time. The complications that occur are generally dose-dependent and once attenuated do not tend to recur. Long-term safety studies regarding improvement in cardiovascular mortality and/or worsening prognosis for patients who develop malignancies are available only in the form of observational studies and randomized controlled long-term trial information is not yet available. The studies reported provide a means for clinicians to ascertain the patients who are likely to derive the greatest benefit from growth hormone when the appropriate diagnostic testing and treatment paradigms are utilized.

SUMMARY

The studies that are summarized provide useful information for assessing the response to treatment, selecting patients who are candidates for long-term replacement therapy and for selecting those in whom the need for therapy may need to be reassessed.

Severe acute pancreatitis due to tamoxifen-induced hypertriglyceridemia with positive rechallenge

CONTEXT

Pancreatitis is a very rare adverse effect of tamoxifen with only six cases of tamoxifen-associated pancreatitis reported in the English literature until now. In these cases, rechallenge with tamoxifen was not carried out.

CASE REPORT

We report a case of recurrent severe acute pancreatitis in a 44-year-old female induced by tamoxifen therapy and review the literature with regards to tamoxifen-associated pancreatitis.

CONCLUSION

Clinicians should be aware of the risks of developing severe acute pancreatitis when using tamoxifen therapy. If tamoxifen is suspected as the probable causative agent, rechallenge with this drug should be prohibited.

Perioperative considerations in diabetic patients

Diabetes mellitus is an increasingly common disease that affects people of all ages, resulting in significant morbidity and mortality. Diabetic patients require more frequent hospitalization, have greater lengths of stay, and cost more to manage than non-diabetics. The major risk factors for diabetics undergoing surgery are the end-organ diseases associated with diabetes: cardiovascular disease, autonomic neuropathy and immune deficiency. Physicians should pay extra attention to preoperative and preprocedure evaluation and treatment of these diseases to ensure optimal perioperative management. Furthermore, these patients unexpectedly develop hemodynamic instability in response to vasopressor or vasodilator administration during anesthesia, this being of particular importance in patients with concurrent ischemic heart disease in whom it may have a direct effect on mortality. Recent studies have shown that tight glycemic control in diabetic patients undergoing major surgery has been shown to improve perioperative morbidity and mortality.

3 Tesla magnetic resonance imaging with and without corticotropin releasing hormone stimulation for the detection of microadenomas in Cushing's syndrome

OBJECTIVE

We sought to determine if higher resolution 3 Tesla (T) magnetic resonance imaging (MRI) with or without ovine corticotropin releasing hormone (o-CRH) stimulation would increase the sensitivity for detection of pituitary microadenomas in ACTH-dependent Cushing's syndrome (CS).

DESIGN AND PATIENTS

We prospectively identified 23 patients over a 2-year period with clinical and biochemical evidence of ACTH-dependent CS with no lesion (n = 11) or equivocal lesion (n = 10) on 1.5T MRI. Subsequently, two additional MRIs were performed in random order: 3T nonstimulated MRI or 3T MRI with o-CRH in all patients. Three neuroradiologists reviewed all examinations in a randomized blinded fashion. Patients were divided into four groups, depending on the outcome of their evaluation and treatment for CS. Two patients had to be excluded, and so we report on 21 subjects.

MEASUREMENTS AND RESULTS

Both 3T MRI without (P < 0.016) and with o-CRH stimulation (P < 0.013) was significantly more sensitive for detection of pituitary microadenomas than 1.5T MRI for Group 1 (definitive proof of Cushing's disease, n = 10). Group 2 (those in group 1, plus three patients where dynamic/invasive testing suggested pituitary source) also showed a significant (P < 0.012) advantage for 3T. There was no difference between the 3T and the 3T o-CRH examinations for any of the pulse sequences. We did not observe a statistically significant difference in other patient groups [patients with recurrent CD (n = 6) and patients with ectopic CS (n = 2)].

CONCLUSIONS

The results of our prospective blinded studies suggest that 3T MRI of pituitary gland should be considered in evaluation of patients with ACTH-dependent CD when 1.5T imaging is negative or equivocal.

The effect of in vivo growth hormone treatment on blood gene expression in adults with growth hormone deficiency reveals potential biomarkers to monitor growth hormone therapy

OBJECTIVE

Growth hormone (GH) replacement therapy is presently utilized in the treatment of adult GH deficiency (AGHD). Adult responses to GH treatment are highly variable and, apart from measurement of IGF-I, few tools are currently available for monitoring GH treatment progress. As GH receptors are expressed in certain blood cell types, changes in gene expression in peripheral blood can reflect perturbations induced as a result of GH therapy.

DESIGN/PATIENTS

We have carried out a pilot study to identify GH-responsive genes in blood, and have assessed the utility of GH-responsive genes in monitoring GH therapy in AGHD. Blood was collected from ten women diagnosed with AGHD syndrome both before and 4 weeks after initiation of GH substitutive therapy. RNA was extracted from peripheral blood mononuclear cells (PBMCs) and changes in response to GH were detected using microarray-based gene analysis.

RESULTS

All patients responded to GH replacement therapy, with serum levels of IGF-I increasing by an average of 307% (P = 0.0003) while IGFBP-3 increased by an average of 182% (P = 0.0002). Serum levels of triglycerides, LDL-C, HDL-C, APOA1 or APOB did not change after 1 month of GH treatment. By contrast, we detected an increase in Lp(a) serum levels (P = 0.0149). Using a stringent selection cutoff of P <or= 0.05, paired analysis identified a set of transcripts that correlated with GH administration. We applied the multivariate statistical technique PLS-DA to the changes in gene expression, demonstrating their utility in differentiating untreated patients and those undergoing GH replacement therapy.

CONCLUSION

This study shows that GH-dependent effects on gene expression in PBMCs can be detected by microarray-based gene analysis, and our results establish a foundation for the further exploration of peripheral blood as a surrogate to detect exposure to GH therapy.

Aldosterone to renin ratio--a reliable screening tool for primary aldosteronism?

Primary aldosteronism (PA) is defined as inappropriately high and (relatively or absolutely) autonomous aldosterone secretion, which is not adequately suppressible by sodium loading. Recent evidence shows that the PA prevalence ranges from 3 to 32%. This high prevalence of PA is suggested to be the result of both more intense screening for PA and improvement of laboratory procedures. Inappropriate high aldosterone secretion is paralleled by severe target organ damage, underlining the importance for the identification of PA at an early stage. The aldosterone to renin ratio (ARR), which reflects aldosterone hypersecretion in regard to its principal trophin renin, is currently considered the most reliable tool for PA screening. Accumulating evidence, however, points to a considerable intra-individual variation of this ratio, emphasizing the importance of standardized screening procedures. In particular, laboratory methods, posture, antihypertensive medication, and dietary salt intake are significant effectors of ARR variation. Furthermore, differentiation between low-renin essential hypertension and PA is difficult and probably arbitrary. It is the purpose of the present review to issue the reliability of the ARR as a screening tool for PA. This review also provides an overview about the physiology of the renin-angiotensin-aldosterone system, highlights current laboratory methods for aldosterone and renin determination, and addresses potential influence factors on the ARR.

The continuum of growth hormone-IGF-I axis defects causing short stature: diagnostic and therapeutic challenges

The growth hormone (GH)-IGF-I axis is essential for normal foetal and childhood growth. Defects at different sites in the axis frequently result in short stature which may compromise adult height. We describe a continuum of clinically relevant abnormalities from GH deficiency through to GH resistance and discuss the implementation and interpretation of investigations. We consider appropriate therapy for patients with abnormal auxology and subnormal adult height prognosis, highlighting new data to clarify therapeutic choices leading to optimal clinical outcome.

Familial hyperaldosteronism I-III

Primary aldosteronism is the most frequent cause of secondary hypertension. Three variants of familial hyperaldosteronism are known today. Early onset hypertension and severe target organ damage are hallmarks of the heritable forms. The underlying gene defect has already been identified in familial hyperaldosteronism type I. In type II and III research is ongoing. A highly variable phenotype often precludes the discovery of the familial appearance of these syndromes. Taking a sound family history is extremely important to discover the Mendelian pattern of inheritance. The identification of affected families is highly rewarding because all variants can potentially be cured or at least specifically treated. Testing the relatives of an index patient sometimes even allows preemptive treatment. However, the availability of specific treatment options necessitates a solid differentiation between the three syndromes to avoid unnecessary medical therapy or surgery.

Salivary aldosterone as a diagnostic aid in primary aldosteronism

Recent evidence demonstrates an increased incidence of primary aldosteronism (PA) in approximately 10% of the hypertensive population, making noninvasive and simple screening methods necessary. The aim of the present study was to apply a time-resolved fluorescence immunoassay for the measurement of aldosterone in saliva and the establishment of a cut-off to identify patients with a high likelihood for PA requiring subsequent screening with the aldosterone to renin ratio. Saliva was collected (AM and PM) to ascertain an optimum time with best discriminating power between healthy and disease states. Plasma aldosterone, after overnight recumbency and 4 h later, was collected for posture testing. The participants included 53 PA patients (aged 14-78), 54 with essential hypertension (EH, aged 19-82), and 38 healthy volunteers (aged 19-56). Saliva aldosterone (SA) (median, 25-75(th)%) in PA was found at 90 pg/ml (61-139) compared to 53 pg/ml (40-85) in EH, with discrimination between PA versus EHs best in the morning (cutoff: 81 pg/ml, 77% sensitivity, 82% specificity). Saliva aldosterone decreases throughout the day in patients with adenomas [APA AM: 123 pg/ml (92-213) vs. PM: 79 pg/ml (41-116)], but not in those with bilateral hyperplasia [BAH AM: 85 pg/ml (59-115)] vs. pm 69 pg/ml (57-114). Morning SA alone allows discrimination between PA and controls, though with significant overlap against EHs, leading to a high number of false positives. More promising is the use of diurnal variation in SA in distinguishing between APA and BAH. The decline in SA seen in patients with APA presents a more constant finding compared to posture testing, which fails to correctly classify a large number of patients.

A comparison of prognostic classification systems for differentiated thyroid carcinoma

OBJECTIVE

To identify and compare prognostic classification systems based on basic tumour characteristics that were developed and/or validated for differentiated thyroid carcinoma (DTC).

DESIGN

Retrospective chart study.

METHODS

Literature was studied using PubMed. Fifteen different prognostic classification systems were identified, of which seven were developed or validated for DTC patients and were based on basic tumour characteristics. These systems were applied to 1225 DTC patients who were treated in our hospital between 1978 and 2002.

RESULTS

Log-rank analysis of Kaplan-Meier cancer-specific survival curves showed that the curve of the Tumor, Lymph-Node, Metastasis (TNM) system had the greatest discriminatory power (log-rank test, log P = -84.9). Cox-regression analysis showed that the TNM system was the most powerful determinant of cancer-specific survival curves. Proportion of variance explained (PVE) analysis showed that the TNM system had the highest PVE.

CONCLUSION

Of the prognostic classification systems analysed in this study, the TNM system performs best in all the three analyses, and is therefore the most suitable for predicting outcome in DTC-patients.

What we still do not know about adrenal vein sampling for primary aldosteronism

During the last two decades, primary aldosteronism has emerged as the most common cause of secondary hypertension, and advances in the diagnosis and treatment of this condition have improved patient care substantially. A major stumbling block in the evaluation and management of these patients, which ultimately guides treatment and prognosis, is answering the question, "Which adrenal gland(s) produce aldosterone?" Adrenal vein sampling has emerged as the only reliable method to determine the answer to this question; however, the methodology and criteria for lateralization have been determined empirically with little prospective data. The major remaining controversies surrounding adrenal vein sampling include: who should perform and who should undergo the procedure; what criteria should be used to define a successful study and lateralization of aldosterone production; whether cosyntropin should be infused during the procedure and how; and what to do when results are ambiguous? This article reviews some of the advances in the execution of this procedure, the variations in procedure, the data that fuel the controversies, and the issues that need to be resolved in the future.

Hormonal responses to the 5-HT1A agonist buspirone in remitted endogenous depressive patients after long-term imipramine treatment

INTRODUCTION

The serotonin-1A (5-HT1A) receptor subtypes are considered as targets of a variety of antidepressant drugs. Previous studies have suggested different adaptive changes in pre- and post-synaptic 5-HT receptors in the brain after treatment with non-selective tricyclic antidepressants (TCA) and selective 5-HT re-uptake inhibitors (SSRIs). The present study aimed to investigate the adaptive effect of the TCA imipramine on the post-synaptic 5-HT1A receptor function in the hypothalamus.

METHODS

A longitudinal design was used in 14 patients with major depressive disorder (DSM-IV) with endogenous features (Newcastle Scale) in order to assess the functional status of post-synaptic 5-HT1A receptors before and after successful antidepressant treatment with imipramine. The effect of the 5-HT1A receptor agonist, buspirone, on ACTH, cortisol, and prolactine (PRL) plasma levels was used to assess the functional status of hypothalamic 5-HT1A receptors. A group of 15 concurrent normal subjects were used as control.

RESULTS

Endogenous depressed patients in remission and currently receiving treatment with imipramine (mean length of treatment 145 days, SD=27) presented significantly lower buspirone responses to ACTH and cortisol than in the pre-treatment condition (Deltamax p< or =.05; AUC p<.001) and to ACTH in comparison with healthy controls (Deltamax p<.01; AUC p<.05). No significant differences were found between the post-treatment and pre-treatment PRL responses, or between patients in both conditions and controls; nevertheless, the PRL response in patients in remission and receiving treatment almost reached the values seen in controls.

CONCLUSIONS

This study extends previous findings from our group using the SSRI citalopram as an antidepressant. Imipramine and citalopram induce similar changes in the endocrine response to buspirone in depressed patients. As the direction of change in ACTH-cortisol and PRL responses after treatment is the opposite, we cannot substantiate increases or decreases in the sensitivity of post-synaptic 5-HT1A receptors in the hypothalamus by long-term imipramine treatment and/or resolution of illness. Therefore, the hormonal changes may result from different or multiples unknown mechanisms.

Management of the infertile couple: an evidence-based protocol

BACKGROUND

Infertility is defined as inability of a couple to conceive naturally after one year of regular unprotected sexual intercourse. It remains a major clinical and social problem, affecting perhaps one couple in six. Evaluation usually starts after 12 months; however it may be indicated earlier. The most common causes of infertility are: male factor such as sperm abnormalities, female factor such as ovulation dysfunction and tubal pathology, combined male and female factors and unexplained infertility.

OBJECTIVES

The aim of this study is to provide the healthcare professionals an evidence-based management protocol for infertile couples away from medical information overload.

METHODS

A comprehensive review where the literature was searched for "Management of infertility and/or infertile couples" at library website of University of Bristol (MetaLib) by using a cross-search of different medical databases besides the relevant printed medical journals and periodicals. Guidelines and recommendations were retrieved from the best evidence reviews such as that from the American College of Obstetricians and Gynaecologists (ACOG), American Society for Reproductive Medicine (ASRM), Canadian Fertility and Andrology Society (CFAS), and Royal College of Obstetricians and Gynaecologists (RCOG).

RESULTS

A simple guide for the clinicians to manage the infertile couples.

CONCLUSIONS

The study deploys a new strategy to translate the research findings and evidence-base recommendations into a simplified focused guide to be applied on routine daily practice. It is an approach to disseminate the recommended medical care for infertile couple to the practicing clinicians.

Vinegar lacks antiglycemic action on enteral carbohydrate absorption in human subjects

The antiglycemic effects of vinegar have been known for more than a century and have been demonstrated in animal as well as human studies. Although the exact mechanism of vinegar action is not known, several possibilities have been proposed including suppression of disaccharidase activity, delayed gastric emptying, enhanced glucose uptake in the periphery and conversion to glycogen, and increased satiety. We hypothesized that by suppressing endogenous insulin secretion, we could estimate the glucose absorption rate from an oral carbohydrate load and determine the effects of vinegar ingestion on this rate. To do so, 5 subjects had 4 studies at 1-week intervals, randomly receiving placebo twice (60 mL water) and vinegar twice (20 mL apple cider vinegar, 40 mL water), followed 2 minutes later by a meal of mashed potatoes (0.75 g carbohydrate per kilogram body weight) that was consumed over 20 minutes. At the beginning of the meal, an oral octreotide/insulin suppression test (25-microg bolus octreotide; 180 minute infusion 5 mU/m(2) body surface area per minute regular human insulin, and 0.5 microg/min octreotide) was begun. Blood samples for insulin and glucose were drawn at 20-minute intervals. The oral octreotide/insulin suppression test suppressed endogenous insulin secretion for the first 100 minutes of the study. During this time, the rate of rise of glucose was modestly but significantly (P = .01) greater after vinegar ingestion compared to placebo, suggesting that vinegar does not act to decrease glycemia by interference with enteral carbohydrate absorption.

Cleaved caspase-3 immunocytochemical staining for pancreatic islets and pancreatic endocrine tumors: A potential marker for biological malignancy

AIMS

Involvement of caspase (C)-3 has been implicated in β-cells from diabetic subjects. This study is aimed to immunocytochemically identify cleaved caspase-3 (CC-3) positive cells in pancreatic endocrine tumors (PETs) compared with control islets.

RESULTS

Control islets revealed some CC-3 positive cells, ranging from 3.6 to 7.3% of total islet cells. Small islets in the pseudocapsule of PETs showed higher immunopositive cells at about 9% for CC -3, suggesting an accelerated apoptosis in these compressed, elongated islets before proceeding to imminent cell death. Majority of primary PETs except 9 cases were negative for CC -3 immunostaining: five insulinomas, one somatostatinoma, one gastrinoma and one pancreatic peptidoma (PPoma) were positive for CC -3.

METHODS

Using commercially available rabbit anti-CC-3, immunocytochemical staining was performed in 42 cases of PETs compared with control islets.

CONCLUSIONS/INTERPRETATION

Majority of primary PETs (28/37, 76%) were negative for CC-3, suggesting that majority of PETs are not on apoptotic program of the normal islets. Since 21 of 24 (88%) of potentially malignant primary non-β-cell PETs were negative, whereas 5 of 12 (42%) benign insulinomas were positive for CC-3 immunostaining, CC-3 negative immunostaining may serve as a possible malignant marker for all PETs.

Assessment of nodular goitre

Nodular goitres are enlargements of the thyroid gland. In the absence of thyroid dysfunction, autoimmune thyroid disease, thyroiditis and thyroid malignancy, they constitute an entity described as non-toxic nodular goitre, which occurs both endemically and sporadically. In the early phase of goitrogenesis, goitres are diffuse and, with time, such goitres tend to become nodular. Concomitantly, thyroid function often becomes autonomous, and therefore the patients gradually develop hyperthyroidism. Some non-toxic goitre patients have no symptoms at all, or just complaints of cosmetic disfigurement. In the diagnostic evaluation protocol, neck palpation and several imaging methods are available: ultrasonography (US), the new developed US elastography, scintigraphy, computed tomography (CT) scan and magnetic resonance imaging (MRI). Fine-needle aspiration biopsy (FNAB) provides the most direct and specific information about a thyroid nodule. Recently, a combination of cytology and molecular testing has shown significant improvement in the diagnostic accuracy and allowed for better prediction of malignancy in thyroid nodular disease.

TSH receptor antibody (TRAb) assays based on the human monoclonal autoantibody M22 are more sensitive than bovine TSH based assays

Measurements of TSH receptor autoantibodies (TRAb) using assays based on the human monoclonal TSH receptor autoantibody M22 or bovine TSH have been compared in 136 adult patients. They suffered from Graves' disease (GD, n=62), Hashimoto's thyroiditis (HT, n=26), or non-autoimmune hyperthyroidism (NAH, n=48) and were selected on the basis of undetectable, borderline or low TRAb levels (0.6-3 IU/l) as measured by TSH based TRAb assay (Dynotest TRAKhuman from BRAHMS). The time interval between initial diagnosis of GD and TRAb determination was high and ranged from 1 month to 3.5 years (median: 2.3 years). Using the kit manufacturer's cutoff values, 53/62 (85.5%) of the selected group of GD patients were TRAb positive (>0.4 IU/l) by M22 based TRAb ELISA (Medizym TRAb clone, Medipan) and 45/62 (72.6%) were TRAb positive (>1.5 IU/l) by TSH based TRAb assay. In the HT group, 9/26 (34.6%) sera were positive in the M22 based ELISA and all but one of these 9 were positive or borderline in the TSH based assay. ROC plot analysis of the GD group using the NAH group as reference showed that at 95% specificity, the bovine TSH based TRAb assay had a sensitivity of 62.9% (cutoff for positivity=1.64 IU/l) and the M22 based TRAb ELISA a sensitivity of 90.3% (cutoff for positivity=0.32 IU/l). Overall therefore, the M22 based Medizym TRAb clone assay is more sensitive than the bovine TSH based Dynotest TRAK human assay.

Pre- versus postmenopausal age, estradiol, and peptide-secretagogue type determine pulsatile growth hormone secretion in healthy women: studies using submaximal agonist drive and an estrogen clamp

CONTEXT

GH-releasing peptide (GHRP), GHRH, and somatostatin are physiological regulators of pulsatile GH secretion.

HYPOTHESIS

Age, independently of abdominal visceral fat (AVF) and basal (nonpulsatile) GH secretion, damps pulsatile GH secretion driven by physiological (rather than pharmacological) amounts of GHRP and GHRH in an experimentally controlled estradiol (E(2)) milieu.

DESIGN AND SETTING

A prospectively randomized, double-blind parallel-cohort study was conducted at an academic medical center.

PARTICIPANTS

Community-dwelling healthy premenopausal (PRE, age 24 +/- 0.8 yr, n = 20) and postmenopausal (POST, age 63 +/- 1.8 yr, n = 22) women participated in the study.

INTERVENTIONS

Gonadal-axis down-regulation with leuprolide was followed by randomized addback of placebo or transdermal E(2) and separate-day iv bolus injections of a half-maximally stimulatory dose of GHRP-2 or GHRH (each 0.33 mug/kg).

ANALYSIS

Three-way analysis of covariance included main factors age, E(2) status, and secretagogue type and covariates AVF and basal GH secretion.

RESULTS

Submaximally stimulated pulsatile GH secretion was positively determined by PRE vs. POST age (P < 0.001), E(2) repletion vs. depletion (P = 0.001) and GHRP-2 vs. GHRH stimulation (P < 0.001), after adjustment for AVF and basal secretion. E(2) vs. placebo elevated fasting mean GH concentrations in both PRE and POST women (P = 0.006) but increased basal (nonpulsatile) GH secretion in PRE only (P = 0.002). PRE vs. POST age prolonged GHRH-driven GH secretory bursts by 36% (P = 0.006).

CONCLUSION

PRE vs. POST age, E(2) availability, and physiological peptide drive are triple determinants of pulsatile GH secretion independently of abdominal visceral fat and nonpulsatile GH secretion in healthy women.