Bioanalysis of lanreotide in dog plasma using liquid chromatography-tandem mass spectrometry and its application in a pharmacokinetic study of beagle dogs after single subcutaneous injection.

Lanreotide is similar to a naturally occurring hormone, somatostatin; thus, it may be used to treat acromegaly or metastatic gastroenteropancreatic neuroendocrine tumours. Here, a bioanalytical method coupling ultra-performance liquid chromatography with tandem mass spectrometry to quantify lanreotide and an internal standard (IS) was developed and validated in dog plasma. The plasma samples were extracted using typical protein precipitation processes. The analyte and internal standard were separated on Phenomenex Kinetex® C18 with 0.1% formic acid and acetonitrile in the mobile phase at a flow rate of 0.4 mL/min. The fragmentation of precursor ions to product ions was optimized at m/z 548.8 â†’ 170.0 for lanreotide [M + 2H]2+ and 472.2 â†’ 436.2 for IS [M + H]+. The peak retention times of lanreotide and IS were 1.09 min and 1.22 min, respectively. The calibration curve samples in dog plasma ranged from 0.3 to 1000 ng/mL and showed good linearity, with a correlation coefficient of r2=0.9996. The lower limit of quantitation was 0.3 ng/mL. The intra- and inter-day precision (relative standard deviation) values for each quality control level were < 9.7 % and < 9.3 %, respectively; intra- and inter-day accuracy were < 109.3% and < 110.4%, respectively. Lanreotide in dog plasma was stable in various conditions. The maximum plasma concentration of lanreotide in male beagle dogs after subcutaneous injection of Somatuline® (lanreotide) Autogel 120 mg was 88.1 ng/mL. The half-life (T1/2) of lanreotide in beagle dogs was long, approximately 198.6 h; the area under the plasma-concentration curve from 0 to 840 h (day 35) was 6,995 ng⋅h/mL. This novel quantification method using UPLC-MS/MS was successfully applied to the pharmacokinetic analysis of lanreotide in dog plasma. The results will assist future studies of drug formulation and repurposing.

Potential for Gut Peptide-Based Therapy in Postprandial Hypotension.

Postprandial hypotension (PPH) is an important and under-recognised disorder resulting from inadequate compensatory cardiovascular responses to meal-induced splanchnic blood pooling. Current approaches to management are suboptimal. Recent studies have established that the cardiovascular response to a meal is modulated profoundly by gastrointestinal factors, including the type and caloric content of ingested meals, rate of gastric emptying, and small intestinal transit and absorption of nutrients. The small intestine represents the major site of nutrient-gut interactions and associated neurohormonal responses, including secretion of glucagon-like peptide-1, glucose-dependent insulinotropic peptide and somatostatin, which exert pleotropic actions relevant to the postprandial haemodynamic profile. This review summarises knowledge relating to the role of these gut peptides in the cardiovascular response to a meal and their potential application to the management of PPH.

Inhibitory Effect of Lactococcus lactis subsp. lactis HFY14 on Diphenoxylate-Induced Constipation in Mice by Regulating the VIP-cAMP-PKA-AQP3 Signaling Pathway.

AIM: The naturally fermented yak yogurt of pastoralists in the Tibetan Plateau, China, because of its unique geographical environment and the unique lifestyle of Tibetan pastoralists, is very different from other kinds of sour milk, and the microorganisms it contains are special. Lactococcus lactis subsp. lactis HFY14 (LLSL-HFY14) is a new lactic acid bacterium isolated from naturally fermented yak yogurt. The purpose of this study was to study the inhibitory effect of the bacterium on constipation. METHODS: Constipation was induced in ICR mice with diphenoxylate, and the constipated mice were treated with LLSL-HFY14. The weight and feces of the mice were visually detected. Colonic tissues were observed on hematoxylin and eosin-stained sections. Serum indices were detected with kits. mRNA expression in the colon was determined by quantitative polymerase chain reaction assay. RESULTS: Constipation caused weight loss, the number of defecation granules, defecation weight, fecal water content decreased, and the first black stool excretion time increased. LLSL-HFY14 alleviated these symptoms, and the effects were similar to those of lactulose (drug). The pathological examination revealed that constipation caused pathological changes in the colon, and LLSL-HFY14 effectively alleviated the disease. LLSL-HFY14 increased serum levels of motilin, gastrin, endothelin, substance P, acetylcholinesterase, and vasoactive intestinal peptide (VIP) and decreased serum levels of somatostatin in constipated mice. In addition, LLSL-HFY14 upregulated VIP, cAMP, protein kinase A, and aquaporin 3 expression in colonic tissues of constipated mice in a dose-dependent manner. CONCLUSION: LLSL-HFY14 inhibited constipation, similar to lactulose, and has the potential to become a biological agent.

Vasoactive Biomarkers Associated With Long-Term Incidence of Symptomatic Peripheral Arterial Disease and Mortality.

We evaluated if plasma biomarkers can predict incident peripheral arterial disease (PAD) and mortality in a longitudinal cohort study. Men (n = 3618) and women (n = 1542) were included in the Malmö Preventive Project and underwent analysis of: C-terminal endothelin-1 (CT-proET-1), N-Terminal prosomatostatin (NT-proSST), midregional proatrial natriuretic peptide (MR-proANP), procalcitonin (PCT), and copeptin. Participants were followed up for incident PAD and mortality until December 31, 2016. Median follow-up was 11.2 years (interquartile range 9.4-12.2). Cumulative incidence of PAD was 4.3% (221/5160), 4.5% in men (164/3618) and 3.7% in women (57/1542; P = .174). In an adjusted Cox proportional hazards regression model, higher CT-proET-1 (hazard ratio [HR] 1.8; 95% confidence interval [CI] 1.4-2.3), NT-proSST (HR 1.5; 95% CI 1.2-2.0), and MR-proANP (HR 1.7; 95% CI 1.3-2.3) were independently associated with incident PAD, and higher CT-proET-1 (HR 1.3; 95% CI 1.2-1.5), NT-proSST (HR 1.2; 95% CI 1.1-1.3), MR-proANP (HR 1.4; 95% CI 1.3-1.6), PCT (HR 1.1; 95% CI 1.0-1.2), and copeptin (HR 1.2; 95% CI 1.1-1.4) were independently associated with mortality. Increased levels of CT-proET-1, NT-proSST, and MR-proANP were independently associated with incident PAD, whereas all the vasoactive biomarkers were independently associated with mortality during follow-up.

Plasma Somatostatin in Advanced Heart Failure: Association with Cardiac Filling Pressures and Outcome.

BACKGROUND: Somatostatin inhibits intestinal motility and hormonal secretion and is a potent arterial vasoconstrictor of the splanchnic blood flow. It is unknown if somatostatin concentrations are associated with central hemodynamic measurements in patients with advanced heart failure (HF). METHODS: A prospective study of HF patients with a left ventricular ejection fraction (LVEF) <45% referred to right heart catheterization (RHC) for evaluation for heart transplantation (HTX) or left ventricular assist device (LVAD). RESULTS: Fifty-three patients were included with mean LVEF 18 ± 8% and majority in NYHA-class III-IV (79%). Median plasma somatostatin concentration was 18 pmol/L. In univariable regression analysis, log(somatostatin) was associated with increased central venous pressure (CVP; r2 = 0.14, p = 0.003) and a reduced cardiac index (CI; r2 = 0.15, p = 0.004). When adjusted for selected clinical variables (age, gender, LVEF, eGFR and BMI), log(somatostatin) remained a significant predictor of CVP (p = 0.044). Increased somatostatin concentrations predicted mortality in multivariable models (hazard ratio: 5.2 [1.2-22.2], p = 0.026) but not the combined endpoint of death, LVAD implantation or HTX. CONCLUSIONS: Somatostatin concentrations were associated with CVP and CI in patients with HF. The pathophysiological mechanism may be related to congestion and/or hypoperfusion of the intestine. Somatostatin was an independent predictor of mortality in advanced HF.

Gel-electromembrane extraction of peptides: Determination of five hypothalamic agents in human plasma samples.

Agarose gel as a green membrane has been proposed for use in electromembrane extraction of five hypothalamic-related peptides without an ionic carrier. Octreotide, goserelin, triptorelin, cetrorelix, and somatostatin were extracted from 5.0 mL of sample solution (adjusted to pH 5.0) into a microvolume acceptor solution (HCl, 100 mM) under the applied voltage of 30 V in 15 min. The pH of the agarose gel 3.0% (w/v) was adjusted to 4.0 to facilitate the movement of peptides through the membrane. Quantification was performed using an HPLC-UV system on a C18 column. Quantification and detection limits were found to be in the range of 15.0-20.0 ng mL-1 and 4.5-6.0 ng mL-1, respectively. Dynamic linear ranges were found to be in the range of 15.0-1000 ng mL-1 (R2 > 0.995) and recoveries were in the range of 62.3-77.6%. The optimized method was applied to spiked human plasma samples. The method showed relative recoveries in the range of 44.8-66.0%. Finally, the proposed method was compared with and shown to have higher recoveries than, the conventional electromembrane extraction method for the peptides under study.

Frequency and Causes of False-Positive Elevated Plasma Concentrations of Fasting Gut Hormones in a Specialist Neuroendocrine Tumor Center.

Introduction: In the UK, the fasting plasma concentrations of a panel of gut hormones (comprising vasoactive intestinal peptide (VIP), gastrin, pancreatic polypeptide (PP), glucagon, somatostatin and chromogranin A) are measured to evaluate patients who have or who (due to unexplained and compatible symptoms) are suspected of having neuroendocrine tumors (NETs). False positive elevated hormone concentrations are sometimes found. Objective: To evaluate the frequency and implications of false positive fasting gut hormone results. Methods: Retrospective audit of fasting gut hormone profile results at a large UK university teaching hospital over 12 months. Results: Fasting gut hormone concentrations were measured in 231 patients during 2017. No NETs were found in the 88 patients who had this test performed only to investigate symptoms. 31 false positive gastrin, 8 false positive chromogranin A, two false positive glucagon, three false positive somatostatin, one false positive PP, and one false positive VIP results were found. We extended the audit for glucagon and somatostatin for an additional two years and found seven probable false-positive raised glucagon concentrations and four probable false-positive elevated plasma somatostatin concentrations in total. Conclusions: False-positive elevations of plasma gastrin and chromogranin A were common and causes such as proton pump inhibitor use or inadequate fasting accounted for most cases. Elevated plasma concentrations of the other gut hormones were also detected in patients who had no other evidence of NET. Other diagnoses (e.g. cirrhosis and medullary thyroid carcinoma for hypersomatostatinemia and type 2 diabetes mellitus, pancreatitis, liver or renal impairment for hyperglucagonemia) may cause these false positive results.

Structure-functional changes in eNAMPT at high concentrations mediate mouse and human beta cell dysfunction in type 2 diabetes.

AIMS/HYPOTHESIS: Progressive decline in functional beta cell mass is central to the development of type 2 diabetes. Elevated serum levels of extracellular nicotinamide phosphoribosyltransferase (eNAMPT) are associated with beta cell failure in type 2 diabetes and eNAMPT immuno-neutralisation improves glucose tolerance in mouse models of diabetes. Despite this, the effects of eNAMPT on functional beta cell mass are poorly elucidated, with some studies having separately reported beta cell-protective effects of eNAMPT. eNAMPT exists in structurally and functionally distinct monomeric and dimeric forms. Dimerisation is essential for the NAD-biosynthetic capacity of NAMPT. Monomeric eNAMPT does not possess NAD-biosynthetic capacity and may exert distinct NAD-independent effects. This study aimed to fully characterise the structure-functional effects of eNAMPT on pancreatic beta cell functional mass and to relate these to beta cell failure in type 2 diabetes. METHODS: CD-1 mice and serum from obese humans who were without diabetes, with impaired fasting glucose (IFG) or with type 2 diabetes (from the Body Fat, Surgery and Hormone [BodyFatS&H] study) or with or at risk of developing type 2 diabetes (from the VaSera trial) were used in this study. We generated recombinant wild-type and monomeric eNAMPT to explore the effects of eNAMPT on functional beta cell mass in isolated mouse and human islets. Beta cell function was determined by static and dynamic insulin secretion and intracellular calcium microfluorimetry. NAD-biosynthetic capacity of eNAMPT was assessed by colorimetric and fluorescent assays and by native mass spectrometry. Islet cell number was determined by immunohistochemical staining for insulin, glucagon and somatostatin, with islet apoptosis determined by caspase 3/7 activity. Markers of inflammation and beta cell identity were determined by quantitative reverse transcription PCR. Total, monomeric and dimeric eNAMPT and nicotinamide mononucleotide (NMN) were evaluated by ELISA, western blot and fluorometric assay using serum from non-diabetic, glucose intolerant and type 2 diabetic individuals. RESULTS: eNAMPT exerts bimodal and concentration- and structure-functional-dependent effects on beta cell functional mass. At low physiological concentrations (~1 ng/ml), as seen in serum from humans without diabetes, eNAMPT enhances beta cell function through NAD-dependent mechanisms, consistent with eNAMPT being present as a dimer. However, as eNAMPT concentrations rise to ~5 ng/ml, as in type 2 diabetes, eNAMPT begins to adopt a monomeric form and mediates beta cell dysfunction, reduced beta cell identity and number, increased alpha cell number and increased apoptosis, through NAD-independent proinflammatory mechanisms. CONCLUSIONS/INTERPRETATION: We have characterised a novel mechanism of beta cell dysfunction in type 2 diabetes. At low physiological levels, eNAMPT exists in dimer form and maintains beta cell function and identity through NAD-dependent mechanisms. However, as eNAMPT levels rise, as in type 2 diabetes, structure-functional changes occur resulting in marked elevation of monomeric eNAMPT, which induces a diabetic phenotype in pancreatic islets. Strategies to selectively target monomeric eNAMPT could represent promising therapeutic strategies for the treatment of type 2 diabetes.

[The influence of chronic intermittent hypoxia on hypothalamic-somatotropic axis in rats].

Objective: To investigate the effects of chronic intermittent hypoxia on somatotropic axis hormone levels in rats. Methods: Mature male Wistar rats were exposed to air or intermittent hypoxia randomly.The serum levels of growth hormone-releasing hormone (GHRH), growth hormone (GH) and somatostatin (SS) were measured before exposure, at the 4th, 8th, and 12th week after exposure. Different hormone levels in two groups were compared and analyzed. Results: Compared with the control group, GHRH levels in chronic intermittent hypoxic group showed a significant decline at the 4th week [(732.77±46.99)pg/ml vs. (893.59±40.00) pg/ml, P<0.05], while SS levels at the 8th week [(30.71±2.27) pg/ml vs. (44.69±3.36) pg/ml, P<0.05] and GH levels at the 12th week [(1.20±0.29) ng/ml vs. (2.06±0.13) ng/ml, P<0.05] were similarly reduced. As the duration of intermittent hypoxia was prolonged, the GHRH levels did not decrease further [4th week (732.77±46.99) pg/ml vs. 8th week (607.54±131.61) pg/ml vs. 12th week (730.05±40.63) pg/ml, P>0.05].However, the serum SS levels decreased further from the 8th week to the 12th week [(30.71±2.27) pg/ml vs. (24.41±4.06) pg/ml, P<0.05]. Conclusion: Chronic intermittent hypoxia might inhibit the function of somatotropic axis. Hypothalamic hormones are the earlyonesto be influenced, thereafter the entire axis.

Glucagon receptor antagonism increases mouse pancreatic δ-cell mass through cell proliferation and duct-derived neogenesis.

Pancreatic δ-cells, which produce somatostatin, play an indispensable role in glucose homeostasis by inhibiting glucagon and insulin secretion in a paracrine manner. Recent studies have shown that δ-cells are couple with ß-cells to suppress α-cell activity. Under certain circumstances, δ-cells could also be trans-differentiated into insulin-producing ß-cells. Thus, pancreatic islet may benefit from δ-cell hyperplasia. However, an effective way to increase δ-cell mass has been rarely reported. Here, we found that REMD 2.59, a human monoclonal antibody and competitive antagonist of the glucagon receptor, massively boosted δ-cell number and increased plasma somatostatin level in both normoglycemic and type 1 diabetic (T1D) mice. The increased δ-cells were due to both δ-cell proliferation and derivation of duct lining cells. Notably, the enlarged δ-cell mass could reduce ß-cell burdens by inducing FoxO1 nuclear translocation in normoglycemic mice. Moreover, some somatostatin-positive cells were co-localized with C-peptide in T1D mice, suggesting that δ-cells might be a source of the newborn ß-cells. Collectively, these observations suggest that treatment with the glucagon receptor monoclonal antibody can increase pancreatic δ-cell mass by promoting self-replication and inducing duct-derived neogenesis both in normoglycemia and diabetic mice.

Association of plasma somatostatin with disease severity and progression in patients with autosomal dominant polycystic kidney disease.

BACKGROUND: Somatostatin (SST) inhibits intracellular cyclic adenosine monophosphate (cAMP) production and thus may modify cyst formation in autosomal dominant polycystic kidney disease (ADPKD). We investigated whether endogenous plasma SST concentration is associated with disease severity and progression in patients with ADPKD, and whether plasma SST concentrations change during treatment with a vasopressin V2 receptor antagonist or SST analogue. METHODS: In this observational study, fasting concentrations of SST were measured in 127 ADPKD patients (diagnosed upon the revised Ravine criteria) by ELISA. cAMP was measured in 24 h urine by Radio Immuno Assay. Kidney function was measured (mGFR) as 125I-iothalamate clearance, and total kidney volume was measured by MRI volumetry and adjusted for height (htTKV). Disease progression was expressed as annual change in mGFR and htTKV. Additionally, baseline versus follow-up SST concentrations were compared in ADPKD patients during vasopressin V2 receptor antagonist (tolvaptan) (n = 27) or SST analogue (lanreotide) treatment (n = 25). RESULTS: In 127 ADPKD patients, 41 ± 11 years, 44% female, eGFR 73 ± 32 ml/min/1.73m2, mGFR 75 ± 32 ml/min/1.73m2 and htTKV 826 (521-1297) ml/m, SST concentration was 48.5 (34.3-77.8) pg/ml. At baseline, SST was associated with urinary cAMP, mGFR and htTKV (p = 0.02, p = 0.004 and p = 0.02, respectively), but these associations lost significance after adjustment for age and sex or protein intake (p = 0.09, p = 0.06 and p = 0.15 respectively). Baseline SST was not associated with annual change in mGFR, or htTKV during follow-up (st. ß = - 0.02, p = 0.87 and st. ß = - 0.07, p = 0.54 respectively). During treatment with tolvaptan SST levels remained stable 38.2 (23.8-70.7) pg/mL vs. 39.8 (31.2-58.5) pg/mL, p = 0.85), whereas SST levels decreased significantly during treatment with lanreotide (42.5 (33.2-55.0) pg/ml vs. 29.3 (24.8-37.6), p = 0.008). CONCLUSIONS: Fasting plasma SST concentration is not associated with disease severity or progression in patients with ADPKD. Treatment with lanreotide caused a decrease in SST concentration. These data suggest that plasma SST cannot be used as a biomarker to assess prognosis in ADPKD, but leave the possibility open that change in SST concentration during lanreotide treatment may reflect therapy efficacy.

Preventive Effect of Lactobacillus fermentum CQPC03 on Activated Carbon-Induced Constipation in ICR Mice.

Background and objectives: Paocai (pickled cabbage), which is fermented by lactic acid bacteria, is a traditional Chinese food. The microorganisms of Paocai were isolated and identified, and the constipation inhibition effect of one of the isolated Lactobacillus was investigated. Materials and Methods: The 16S rDNA technology was used for microbial identification. A mouse constipation model was established using activated carbon. After intragastric administration of Lactobacillus (108 CFU/mL), the mice were dissected to prepare pathological sections of the small intestine. Serum indicators were detected using kits, and the expression of small intestine-related mRNAs was detected by qPCR assay. Results: One strain of Lactobacillus was identified and named Lactobacillus fermentum CQPC03 (LF-CQPC03). Body weight and activated carbon propulsion rate were all higher in mice intragastrically administered with LF-CQPC03 compared with the control group, while the time to the first black stool in treated mice was lower than that in the control group. Serum assays showed that gastrin (Gas), endothelin (ET), and acetylcholinesterase (AchE) levels were significantly higher in the LF-CQPC03-treated mice than in the control group, while somatostatin (SS) levels were significantly lower than in the control mice. Mouse small intestine tissue showed that c-Kit, stem cell factor (SCF), and glial cell-derived neurotrophic factor (GDNF) mRNA expression levels were significantly higher in the LF-CQPC03 treated mice than in control mice, while transient receptor potential cation channel subfamily V member 1 (TRPV1) and inducible nitric oxide synthase (iNOS) expression levels were significantly lower in the LF-CQPC03 treated mice than in control mice. Conclusions: There is a better effect with high-dose LF-CQPC03, compared to the lower dose (LF-CQPC03-L), showing good probiotic potential, as well as development and application value.

Effect of the Orally Active Growth Hormone Secretagogue MK-677 on Somatic Growth in Rats.

PURPOSE: Growth hormone secretagogues (GHSs) possess the ability to release growth hormone (GH) in the body. This study aimed to investigate the effects of MK-677, an orally active GHS, on somatic growth in rats. MATERIALS AND METHODS: The serum levels of GH were measured after oral administration of MK-677 to confirm GH stimulatory effects. Body weight, body length, tibia length, epiphyseal plate width, and serum levels of insulin-like growth factor (IGF)-I were measured after oral administration of 4 mg/kg of MK-677 for 6 weeks to investigate growth-promoting effects. RESULTS: Oral administration of MK-677 at 4 mg/kg increased peak GH concentrations by 1.8-fold, compared to baseline. However, oral administration of MK-677 for 6 weeks did not increase body growth or serum levels of IGF-I. At 6 weeks after treatment, the GH response to MK-677 was abolished. Pituitary GH mRNA and hypothalamic GH-releasing hormone mRNA, and GH secretagogue receptor (GHSR) mRNA expression in the pituitary and hypothalamus did not differ between the control and treatment group. Somatostatin (SST) mRNA expression in the hypothalamus was markedly increased in the treatment group, whereas SST receptor (SSTR)-2 mRNA expression in the pituitary gland was decreased. Protein expression of hypothalamic GHSR, SST, and pituitary SSTR-2 showed patterns similar to those for mRNA expression. CONCLUSION: Our results suggest that prolonged administration of MK-677 in rats does not promote growth despite the GH stimulatory effect of MK-677, which may be related to increased expression of SST in the hypothalamus. Further studies are needed to overcome the observed desensitization to GHS.

Relationship between somatostatin and interleukin-6: A cross-sectional study in patients with acute pancreatitis.

OBJECTIVES: The aim of the analysis is to determine dynamic changes in somatostatin (SS) and interleukin-6 (IL-6) concentrations during in acute pancreatitis (AP). METHODS: The influence of tobacco smoking on IL-6 and SS levels in the serum of non-smoking (n = 10) and smoking (n = 27) patients with diagnosed AP and control group: non-smoking (n = 44), smoking (n = 42) and passive smoking (n = 29) healthy persons was proved. The concentration of IL-6 and SS was determined by means of ELISA. Differences between the groups analyzed were tested using the U Mann Whitney test. The Spearman rank correlation analysis was used to evaluate the correlations. RESULTS: The concentrations of IL-6 and SS were significantly higher in smoking patients with AP and healthy persons when compared with non-smoking population on every day (1 day: p = 0.0002, p = 0.015; 3 day: p = 0.005, p = 0.001 and 7 day: p = 0.025, p = 0.038). Dynamic changes in concentrations of IL-6 and SS in the serum of patients with AP were demonstrated in the ensuing days of the disease. In case of non-smoking and smoking patients, significant positive correlations between IL-6 and SS was observed. CONCLUSIONS: These findings suggest that some of the antiinflammatory effects of SS against acute pancreatitis may be mediated by reducing the local proinflammatory cytokine secretion in the pancreas.

Association between serum somatostatin levels and glucose-lipid metabolism in the Jino ethnic minority and Han Chinese population.

We aim to investigate the relationship between serum somatostatin (SST) levels and glucose-lipid metabolism at various stages of glucose tolerance in the Jino ethnic minority (n=111) and Han population (n=113) of Yunnan Province, southwest China. Anthropometric parameters and biochemical traits were measured. Serum SST and plasma glucagon levels were tested. Participants were divided into three subgroups: isolated fasting hyperglycemia (IFH), isolated post challenge hyperglycemia (IPH) and normal glucose tolerance (NGT). SST levels were found lower while glucagon levels were significantly higher in the Jino ethnic with IPH (P=0.0026 and P=0.0069, respectively). Fasting glucose and high density lipoprotein-cholesterol (HDL-C) levels were higher (P=0.0055 and P=0.0021, respectively) and fasting insulin levels and homeostasis model assessments ß-cell function were lower (P=0.0479 and P=0.0007, respectively) in the Jino population. After adjusting for confounding factors, the serum SST level was associated with glucagon (P<0.0001) in both populations. The SST level was correlated with fasting Cpeptide (P=0.0267) in Jino and HDL-C levels in Han (P=0.0079). Our findings suggest that serum SST levels and plasma glucagon levels may vary in subjects with IPH between two ethnics.

Sensitive quantification of the somatostatin analog AP102 in plasma by ultra-high pressure liquid chromatography-tandem mass spectrometry and application to a pharmacokinetic study in rats.

AP102 is a di-iodinated octapeptide somatostatin agonist (SSA) designed to treat acromegaly and neuroendocrine tumors. A sensitive and selective method was validated for the quantification of AP102 in plasma following the European Medicines Agency (EMA) and Food and Drug Administration (FDA) guidelines. Sample preparation was performed using solid-phase extraction microplates. Chromatographic separation was achieved on an ultra-high pressure liquid chromatography (UHPLC) C18 column in 6.0 minutes. The compounds were quantified using multiple reaction monitoring on a tandem quadrupole mass spectrometer with 13 C,15 N-labeled AP102 as internal standard. Calibration ranged from 50 to 10000 pg/mL. The lower limit of quantification (LLOQ) was measured at 20 pg/mL, and robust analytical performances were obtained with trueness at 99.2%-100.0%, intra-assay imprecision at 2.5%-4.4%, and inter-assay imprecision at 8.9%-9.7%. The accuracy profiles (total error) built on the 3 concentrations levels showed accuracy within the 70%-130% range. AP102 is remarkably stable since no proteolytic fragments were detected on plasma samples analyzed by Orbitrap-MS. Pharmacokinetic studies were conducted in rats, after single dose (1, 3, and 10 µg/kg, sc) and continuous subcutaneous administration (osmotic minipumps for 28 days, 3.0 or 10.0 µg/kg/h). AP102 showed a rapid absorption by the subcutaneous route (Tmax : 15-30 minutes) and a fast elimination (t1/2 : 33-86 minutes). The PK profile of AP102 exhibited a mean clearance of 1.67 L/h and a mean distribution volume at steady state of 7.16 L/kg, about 10-fold higher than those observed with other SSA or non- and mono-iodinated AP102. LogD7.4 determination confirmed the lipophilic properties of AP102 that might influence its distribution in tissues.

N-Terminal Prosomatostatin and Risk of Vascular Dementia.

BACKGROUND: Increased somatostatin plasma concentration has been found in patients with vascular dementia. However, it is unknown whether or not somatostatin levels may predict dementia development in the general population. To this end, we sought to assess the association of circulating N-terminal prosomatostatin (NT-proSST) with incident dementia among community-dwelling older adults. METHODS: In the prospective population-based Malmö Preventive Project, 5,347 study participants (mean age: 69 ± 6years; 70% men) provided plasma for the determination of NT-proSST concentration. Of these, 373 participants (7%) were diagnosed with dementia (120 Alzheimer's disease, 83 vascular, 102 mixed, and 68 other aetiology) during a follow-up period of 4.6 ± 1.3 years. The association of NT-proSST with the risk of dementia and its subtypes was studied using multivariable-adjusted Cox regression models controlling for age, gender, body mass index, systolic blood pressure, antihypertensive treatment, smoking, diabetes, lipid levels and prevalent stroke. RESULTS: Higher levels of NT-proSST were significantly associated with an increased risk of vascular dementia (hazard ratio [HR] per 1 SD: 1.29; 95% CI 1.05-1.59; p = 0.016), whereas no association was observed with Alzheimer's disease (HR per 1 SD: 0.99; 95% CI 0.81-1.20; p = 0.91), all-cause dementia (HR per 1 SD: 1.04; 95% CI 0.94-1.16; p = 0.44), and mixed dementia (HR per 1 SD: 0.98; 95% CI 0.79-1.21; p = 0.84). Levels of NT-proSST above 563 pmol/L (highest quartile) conferred distinctly increased risk of vascular dementia (HR 1.66; 95% CI 1.05-2.63; p = 0.029) compared with lower values. CONCLUSIONS: Higher levels of circulating N-terminal-prosomatostatin are associated with increased incidence of vascular dementia. Our findings might be of importance for the understanding of dementia development in older adults.

Phase II study of lanreotide autogel in Japanese patients with unresectable or metastatic well-differentiated neuroendocrine tumors.

Background Lanreotide is a long-acting somatostatin analog with demonstrated efficacy against enteropancreatic neuroendocrine tumor (NET) in the phase III (CLARINET) study. Materials and Methods In this single-arm study, Japanese patients with grade (G) 1/G2 NET received lanreotide (120 mg/4 weeks) for 48 weeks. Those who completed the study were enrolled in a long-term extension study. The primary endpoint was the clinical benefit rate (CBR) defined as a complete response, partial response (PR), or stable disease (SD) over 24-weeks. Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), safety, and pharmacokinetics. Results Thirty-two patients were recruited at 10 sites. The full analysis set (FAS) comprised 28 patients. Primary tumors were located in pancreas (12 patients), foregut (non-pancreas, lung; 1), midgut (2), hindgut (8), and unknown (5). Four patients had gastrinoma of the functional NET, and 3 had multiple endocrine neoplasia type 1. In the FAS, 39.3% had progressive disease at baseline. The CBR at 24 weeks was 64.3% (95% confidence interval; CI: 44.1-81.4), and median PFS was 36.3 weeks (95% CI: 24.1-53.1). PR was confirmed in 1 patient at 60 weeks during the extension study (ORR: 3.6%). Frequent adverse events related to lanreotide included injection site induration (28.1%), faeces pale (18.8%), flatulence (12.5%), and diabetes mellitus (12.5%). Conclusions The efficacy and safety of lanreotide in this study indicated its usefulness as a treatment option for Japanese NET patients. TRIAL REGISTRATION: JapicCTI-132,375, JapicCTI-142,698.

Evidence for a novel, neurohumoral antinociceptive mechanism mediated by peripheral capsaicin-sensitive nociceptors in conscious rats.

Stimulation of capsaicin-sensitive peripheral sensory nerve terminals induces remote anti-inflammatory effects throughout the body of anesthetized rats and guinea-pigs mediated by somatostatin. As somatostatin has also antinociceptive effects, the study aimed at investigating whether similar remote antinociceptive effects can be demonstrated in awake animals. In conscious rats, nociceptive nerve endings of the right hind paw decentralized by cutting the sciatic and saphenous nerves 18h before were chemically stimulated, and drop of the noxious heat threshold (heat hyperalgesia) induced by prior (18h before) plantar incision was measured on the contralateral, left hind paw using an increasing-temperature water bath. 18h after nerve transection, mustard oil-evoked plasma extravasation was not significantly reduced in the right hind paw as tested by in vivo fluorescence imaging. Applying agonist of either transient receptor potential vanilloid 1 (TRPV1) or transient receptor potential ankyrin 1 (TRPA1) receptor (capsaicin or mustard oil, respectively) to the nerve-transected paw inhibited the plantar incision-induced drop of the noxious heat threshold on the contralateral paw. The onset of these remote antihyperalgesic effects was 10-20min. A similar contralateral inhibitory effect of capsaicin or mustard oil treatment was observed on neuropathic mechanical hyperalgesia evoked by partial sciatic nerve injury 2days before nerve transection and measured by a Randall-Selitto apparatus. The remote thermal antihyperalgesic effect was prevented by chronic (5days) denervation or local capsaicin desensitization of the stimulated paw; reduced by intraperitoneally applied antagonist of somatostatin (cyclosomatostatin) or opioid receptors (naloxone). The response was mimicked by intraperitoneally applied somatostatin and associated with a 72±27% increase in plasma somatostatin-like immunoreactivity that was absent after chronic (5days) denervation. In conclusion, chemical activation of decentralized peripheral capsaicin-sensitive nociceptors evokes remote antihyperalgesic responses initiated outside the central nervous system and mediated by somatostatin and endogenous opioids.

Plasma N-terminal Prosomatostatin and Risk of Incident Cardiovascular Disease and All-Cause Mortality in a Prospective Observational Cohort: the PREVEND Study.

BACKGROUND: Somatostatin is a component of the well-known insulin-like growth factor-1/growth hormone (GH) longevity axis. There is observational evidence that increased GH is associated with an increased risk of cardiovascular disease (CVD). We aimed to investigate the potential association of plasma N-terminal fragment prosomatostatin (NT-proSST) with incident CVD and all-cause mortality in apparently healthy adults. METHODS: We studied 8134 participants without history of CVD (aged 28-75 years; women, 52.6%) from the Prevention of Renal and Vascular End-stage Disease (PREVEND) study in Groningen, the Netherlands. Plasma NT-proSST was measured in baseline samples. Outcomes were incidence of CVD and all-cause mortality. RESULTS: In cross-sectional analyses, NT-proSST [mean (SD), 384.0 (169.3) pmol/L] was positively associated with male sex and age (both P < 0.001). During a median follow-up of 10.5 (Q1-Q3: 9.9-10.8) years, 708 (8.7%) participants developed CVD and 517 (6.4%) participants died. In univariable analyses, NT-proSST was associated with an increased risk of incident CVD and all-cause mortality (both P < 0.001). In multivariable analyses, these associations were independent of the Framingham risk factors, with hazard ratios (95% CI) per doubling of NT-proSST of 1.17 (1.03-1.34; P = 0.02) for incident CVD and of 1.28 (1.09-1.49; P = 0.002) for all-cause mortality. Addition of NT-proSST to the updated Framingham Risk Score improved reclassification (integrated discrimination improvement (P < 0.001); net reclassification improvement was 2.5% (P = 0.04)). CONCLUSIONS: Plasma NT-proSST is positively associated with increased risk of future CVD and all-cause mortality, partly independent of traditional CVD risk factors. Further research is needed to address the nature of associations.