Lee Armstrong

Peptide YY, Cholecystokinin, Insulin and Ghrelin Response to Meal did not Change, but Mean Serum Levels of Insulin is Reduced in Children with Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is a contiguous gene syndrome characterized by uncontrollable eating or hyperphagia. Several studies have confirmed that plasma ghrelin levels are markedly elevated in PWS adults and children. The study of anorexigenic hormones is of interest because of their regulation of appetite by negative signals. To study the pattern and response of the anorexigenic hormones such as cholecystokinin (CCK) and peptide YY (PYY) to a meal in PWS, we measured the plasma CCK, PYY, ghrelin and serum insulin levels in PWS patients (n=4) and in controls (n=4) hourly for a day, and analyzed hormone levels and hormonal responses to meals. Repeated measures of ANOVA of hormone levels demonstrated that only insulin levels decreased (p=0.013) and CCK (p=0.005) and ghrelin (p=0.0007) increased in PWS over 24 hr. However, no significant group x time interactions (ghrelin: p=0.89, CCK: p=0.93, PYY: p=0.68 and insulin: p=0.85) were observed; in addition, there were no differences in an assessment of a three-hour area under the curve after breakfast. These results suggest that the response pattern of hormones to meals in PWS patients parallels that of normal controls. In addition, the decrease of insulin levels over 24 hr, in spite of obesity and elevated ghrelin levels, suggests that the baseline insulin level, not the insulin response to meals, may be abnormal in patients with PWS.

Validation of Neurokinin A Assays in the United States and Europe

Objectives: International cooperative group trials require specific, sensitive biomarker assays that are validated between continents. Neurokinin A (NKA) has been shown to be a powerful independent predictor of a poor prognosis in well-differentiated midgut neuroendocrine tumors. We hypothesized that NKA concentrations of clinical specimens evaluated in NKA assays in the United States and the United Kingdom would be equivalent, even though assay techniques were significantly different. Methods: Frozen clinical specimen aliquots were shipped from the United States to the United Kingdom (n = 67), and from United Kingdom to the United States (n = 50). In addition, spiked plasma standards and medium-spiked standards were exchanged. Samples from the United States were directly assayed in a radioimmunoassay, whereas the UK specimens were extracted, and the reconstituted specimens assayed in the radioimmunoassay. Neurokinin A values from the 2 studies were analyzed by regression analysis. Results: The NKA values from the US and UK laboratories were essentially identical (United States to United Kingdom, r2 = 0.88, P < 0.0001; and United Kingdom to United States, r2 = 0.96, P < 0.0001). Conclusions: Validation of biomarker assays across continents will ensure that laboratory observations made by researchers are equivalent and that prediction of clinical outcomes based on these assays is also reliable.

Neuroendocrine tumours of the small bowel: interpretation of raised circulating chromogranin A, urinary 5 hydroxy indole acetic acid and circulating neurokinin A

BACKGROUND Neuroendocrine tumours (NETs) of the small bowel are difficult to diagnose as symptoms are non-specific and more often found in common gastrointestinal diseases. Chromogranin A (CGA), urinary 5 hydroxy indole acetic acid (U-5HIAA) and Neurokinin A (NKA) are used as laboratory diagnostic tests but results may be misleading or confusing. AIM To clarify the relevance of NET biomarkers for diagnosis of small bowel NETs. DESIGN A review of laboratory test results. METHODS We reviewed 500 consecutive raised plasma CGA, U-5HIAA and plasma NKA, results from patients in N Ireland. The diagnosis of NET was confirmed by the Northern Ireland Cancer Registry. RESULTS In 500 specimens recording raised CGA, 52.2% were from patients with NETs, 13.6% being small bowel tumours, 5.4% of specimens from patients with auto-immune atrophic gastritis and 15.4% from patients taking proton pump inhibitors. In 500 specimens with raised U-5HIAA, 87.8% were from patients with NETs, 68.2% being small bowel tumours. Lung NETs contributed 12.2% and NETs from other sites, 7.4%. Of 500 specimens with raised NKA (reference range (RR) > 20 ng/L), 72.6% were from patients with small bowel NETs and 6% specimens from patients with other NETs. In 20% of specimens NKA concentrations were 21-23 ng/L, within limits of assay precision. CONCLUSION CGA remains the best general circulating marker for NETs although only half of raised test results are due to an NET. U-5HIAA is an excellent marker for small bowel and lung NETs with 80% of high test results confirming these diagnoses. NKA is the most specific biomarker for small bowel NETs.

Biochemical markers of placental dysfunction in assisted conception

Abstract A possible mechanism for poor perinatal outcomes in singleton pregnancies conceived following assisted reproductive technologies (ART) and those conceived naturally following a period of infertility (>12 months) is thought to be placental dysfunction. This was investigated by measuring plasma concentrations of biochemical markers: (i) soluble fms-like tyrosine kinase1 (sFlt1); (ii) placental growth factor (PlGF); (iii) leptin; and (iv) plasminogen activator inhibitor 2 (PAI-2), serially at four antenatal time points. Baseline concentrations of each marker after delivery were also measured. The control group was naturally conceived singleton pregnancies with no history of infertility. Non-smoking, age-matched nulliparous women with no significant medical history were recruited to all groups. The ART group had significantly lower mean plasma concentrations of PlGF at all antenatal time points compared to the control group (p < 0.001). The subfertility (SF) group had significantly higher mean serum concentrations of leptin than the other groups at all time points (p < 0.001), even after correction for body mass index. There were no significant differences in sFlt1 and PAI-2 concentrations between the groups. Low plasma PlGF concentrations in the ART group might suggest abnormal placentation and/or abnormal function in ART pregnancies with relevance to pathogenesis of pregnancy complications in these women.

Comparison of three commercial methods for chromogranin A measurement.

involved in the management of patients with NETs with the imaging techniques and imaging patterns seen in NETs. We will emphasize the growing complementary role of hybrid molecular imaging to conventional diagnostic methods in the management of NETs. Methods: A review of the literature and local experience in imaging of NETs. Results: Depending on the molecular properties of the tumour, radiopharmaceuticals such as meta-iodobenzylguanidine (MIBG), somatostatin receptor scintigraphy (SRS) and positron emission tomography combined with CT (PETCT) using [F] Fluoro-deoxyglucose, [F] Fluorodopamine and Ga-DOTATATE/DOTATOC play an increasingly important part in the management of NETs. Discussion: Identification and staging of NETs with conventional imaging methods such as sonography, computerized tomography and magnetic resonance imaging can be challenging and sometimes unhelpful. Molecular imaging aims to overcome some of the weaknesses of conventional diagnostic methods with the use of specific radiolabelled tracers and hybrid imaging resulting in increased accuracy of localization, staging and characterization of NETs.

Difficulty of diagnosis of gastrinoma with gastrin assay

incubation of peptides with each cell line and analysis of catabolites by mass spectrometry, it was found that bradykininwas highly labile and each antagonist was highly stable under the conditions employed. Bradykinin signalling pathways are thus worthy of further investigation in human prostate cancer cell lines and the evidence presented here would suggest the testing of efficacy in animal models of prostate cancer as a positive outcome could lead to a drug development programme for the treatment of this disease.