Effects of Somatostatin Analogs and Dopamine Agonists on Insulin-Like Growth Factor 2-Induced Insulin Receptor Isoform A Activation by Gastroenteropancreatic Neuroendocrine Tumor Cells.

BACKGROUND: Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) express insulin-like growth factor (IGF)-related factors [IGF1, IGF2; insulin receptor (IR)-A, IR-B; IGF-binding protein (IGFBP) 1-3] as well as somatostatin (SSTRs) and dopamine D2 receptors (D2Rs). OBJECTIVES: To (1) compare mRNA expression of IGF-related factors in human pancreatic NET (panNET) cell lines with that in human GEP-NETs to evaluate the usefulness of these cells as a model for studying the IGF system in GEP-NETs, (2) determine whether panNET cells produce growth factors that activate IR-A, and (3) investigate whether somatostatin analogs (SSAs) and/or dopamine agonists (DAs) influence the production of these growth factors. METHODS: In panNET cells (BON-1 and QGP-1) and GEP-NETs, mRNA expression of IGF-related factors was measured by quantitative real-time PCR. Effects of the SSAs octreotide and pasireotide (PAS), the DA cabergoline (CAB), and the dopastatin BIM-23A760 (all 100 nM) were evaluated at the IGF2 mRNA and protein level (by ELISA) and regarding IR-A bioactivity (by kinase receptor activation assay) in panNET cells. RESULTS: panNET cells and GEP-NETs had comparable expression profiles of IGF-related factors. Especially in BON-1 cells, IGF2 and IR-A were most highly expressed. PAS + CAB inhibited IGF2 (-29.5 ± 4.9%, p < 0.01) and IGFBP3 (-20.0 ± 4.0%, p < 0.01) mRNA expression in BON-1 cells. In BON-1 cells, IGF2 protein secretion was significantly inhibited with BIM-23A760 (-23.7 ± 3.8%). BON-1- but not QGP-1- conditioned medium stimulated IR-A bioactivity. In BON-1 cells, IR-A bioactivity was inhibited by BIM-23A760 and PAS + CAB (-37.8 ± 2.1% and -30.9 ± 4.1%, respectively, p < 0.0001). CONCLUSIONS: (1) The BON-1 cell line is a representative model for studying the IGF system in GEP-NETs, (2) BON-1 cells produce growth factors (IGF2) activating IR-A, and (3) combined SSTR and D2R targeting with PAS + CAB and BIM-23A760 suppresses IGF2-induced IR-A activation.

Genetic testing in clinical practice.

In the practice of internal medicine, the value of genetic testing in common (mono)genetic diseases such as familial hemochromatosis, hypercholesterolemia, Mediterranean fever, and thrombophilia is limited. The genotype insufficiently predicts the phenotype because of the powerful effects of other modifying genes, environmental influences, and lifestyle factors. Many common diseases, including diabetes mellitus, osteoporosis, and cardiovascular disease, have strong genetic influences but are called complex genetic traits. The underlying genetic factors are currently investigated using new molecular tools such as genome-wide association studies, analyzing up to 500,000 markers in huge numbers of patients. Many new (often unexpected) markers have been identified, and in many instances their functional significance is unknown. Genomic profiles play a rapidly growing role in the field of pharmacogenomics. A number of recently identified pharmacogenomic biomarkers are helpful to predict drug-related toxic effects.

Androgen receptor gene CAG repeat polymorphism in longitudinal height and body composition in children and adolescents.

OBJECTIVE: The number of CAG repeats within the CAG repeat polymorphism of the androgen receptor (AR) gene correlates inversely with the transactivation of the receptor. We investigated the relationship between the AR CAG repeat polymorphism and longitudinal growth, puberty and body composition from prepuberty until young adult age. DESIGN: Observational study with repeated measurements. SUBJECTS: Two comparable young Dutch cohorts. The first cohort consisted of 226 subjects. Measurements were performed from 13 until 36 years of age. The second cohort consisted of 244 subjects. Measurements in this cohort were performed from 8 until 14 years of age. MEASUREMENTS: Associations between height, height velocity, weight, BMI, fat mass, fat-free mass and pubertal development and CAG repeat length were measured. RESULTS: Height-standard deviation scores (SDS) were inversely associated with AR CAG repeat length in boys at young, prepubertal and early pubertal age. This association diminishes in the following years and completely disappears after the age of 16 years. No associations were found with pubertal stage or any of the other parameters for body composition. CONCLUSIONS: AR CAG repeat length is inversely associated with longitudinal height in young boys, before the onset of puberty. During puberty, these differences disappear, possibly overruled by a strongly developing hypothalamic-pituitary-gonadal axis.

Occurrence of impaired fasting glucose in GH-deficient adults receiving GH replacement compared with untreated subjects.

OBJECTIVE: The effects of GH replacement on glucose metabolism in GH-deficient (GHD) adults in clinical practice are not well defined. Therefore, we assessed GH treatment effects on fasting plasma glucose (FPG) and haemoglobin A1c (A1c) concentrations in GHD adults in a clinical setting. DESIGN: Post-hoc analysis of the observational Hypopituitary Control and Complications Study conducted at 157 US centres (1997-2002). PATIENTS: GH-deficient adults who were GH-naïve at study entry and had at least two FPG measurements. MEASUREMENTS: Effect of GH treatment on the frequency and time course of abnormal FPG (> or =5.6 mmol/l) development, FPG normalization, progression of increased FPG and abnormal follow-up A1c (>6%) values in GHD patients treated with GH (n = 403) or untreated (n = 169) at their physician's discretion. RESULTS: In subjects without pre-existing diabetes mellitus, development of an abnormal FPG tended to occur in a greater percentage of GH-treated than untreated subjects (35.3% versus 24.5, P = 0.06). Additionally, GH treatment was associated with a mild, transient increase in FPG and shorter time to development of an abnormal FPG in these subjects (P < 0.01). Most ( approximately 80%) abnormal FPG values were below 7 mmol/l and normalized in 69% of GH-treated subjects without diabetes. Treatment with GH had no effect on the rate of FPG normalization, progression of increased FPG or abnormal follow-up A1c values. CONCLUSIONS: Initiation of GH replacement in GHD adults was associated with a mild increase in FPG that often normalized spontaneously. Nevertheless, clinicians should monitor FPG in patients receiving GH treatment.

Role of somatostatin receptors in normal and tumoral pituitary corticotropic cells.

Normal and tumoral pituitary corticotropic cells express sst(2) and sst(5), of which sst(5) is the predominantly expressed receptor subtype. Somatostatin (SS) inhibits pituitary adrenocorticotropin hormone (ACTH) secretion in vitro, but the sensitivity to SS is strongly regulated by glucocorticoids. In pathological conditions of a low endogenous cortisol level, i.e. in patients with adrenal insufficiency and in patients with Nelson's syndrome, SS and sst(2)-preferring SS analogs (SSA), such as octreotide, are able to lower circulating ACTH and cortisol levels. On the other hand, sst(2)-preferring SSA seem not effective in lowering ACTH and cortisol levels in patients with untreated Cushing's disease (CD), in which circulating cortisol levels are high. This is likely due to the downregulation of sst(2) receptors by glucocorticoids. sst(5) receptor expression is more resistant to the inhibitory effect of glucocorticoids. In recent years, novel sst subtype-selective and universal SSA have been developed. In particular, SSA with a high sst(5)-binding affinity are potent inhibitors of ACTH secretion by pituitary corticotropic adenoma cells. This knowledge has initiated clinical trials evaluating the efficacy of these novel SSA in patients with CD, with the aim to lower circulating ACTH and cortisol levels by targeting multiple ssts on the corticotropic adenoma cells. In this minireview, the effects of SS in the regulation of normal and tumoral ACTH secretion, the role of sst subtypes involved herein, as well as the potentials of novel SSA in the treatment of patients with recurrent or persisting CD are discussed.

The medical treatment of Cushing's disease: effectiveness of chronic treatment with the dopamine agonist cabergoline in patients unsuccessfully treated by surgery.

BACKGROUND: The role of dopamine agonists in the treatment of Cushing's disease (CD) has been previously debated. AIM: The aim of this study was to evaluate the effectiveness of short-term (3 months) and long-term (12-24 months) treatment with cabergoline in patients with CD. PATIENTS AND METHODS: 20 patients with CD unsuccessfully treated by surgery entered the study. Cabergoline was administered at an initial dose of 1 mg/wk, with a monthly increase of 1 mg, until urinary cortisol levels normalized or the maximal dose of 7 mg/wk was achieved. The responsiveness to treatment was evaluated according to changes in urinary cortisol excretion. A decrease greater than 25% was considered as a partial response, whereas complete normalization was considered as a full response at short-term evaluation; persistence of normal cortisol excretion was the only criterion to evaluate the response at long-term evaluation. RESULTS: After short-term treatment, 15 (75%) patients were responsive to cabergoline treatment. Among these, normalization of cortisol excretion was maintained in 10, whereas treatment escape was observed in five patients after 6-18 months. Among the 10 long-term responsive patients, eight were followed for 24 months, whereas the remaining two were followed for 12-18 months, due to cabergoline withdrawal for intolerance. A sustained control of cortisol secretion for 24 month cabergoline treatment at the maximal dose ranging from 1-7 mg/wk (median: 3.5) without significant side effects, was obtained in eight of 20 (40%) patients. CONCLUSIONS: The results of this study demonstrated that cabergoline treatment is effective in controlling cortisol secretion for at least 1-2 yr in more than one third of a limited population of patients with CD. If this evidence is confirmed by additional studies, this agent may be considered as a useful treatment option in patients with CD who are unsuccessfully treated by neurosurgery.

Glucocorticoid receptor gene variant is associated with increased body fatness in youngsters.

OBJECTIVE: Sensitivity to glucocorticoids is known to be highly variable between individuals and is partly determined by polymorphisms in the glucocorticoid receptor (GR) gene. We investigated the relationship between four GR gene polymorphisms and body composition during puberty and at young adult age. DESIGN: An observational study with repeated measurements. PATIENTS: Two comparable young Dutch cohorts with a generational difference of about 20 years were investigated. The first cohort consisted of 284 subjects born between 1961 and 1965. Measurements were performed from 13 to 36 years of age. The second cohort consisted of 235 subjects born between 1981 and 1989. Measurements were performed from 8 to 14 years of age. MEASUREMENTS: Associations between height, weight, BMI, fat mass (FM) and fat-free mass and four well-known functional polymorphisms were investigated. Results In boys in the younger cohort, the G-allele of the BclI polymorphism (haplotype 2) was associated with a higher body weight, weight-SDS, BMI, BMI-SDS and FM. These associations were not observed in the older cohort. Irrespective of genotype, the younger cohort showed a significantly higher total FM, body weight and BMI compared with the older cohort. CONCLUSIONS: Because the associations between the G-allele of the BclI polymorphism in the GR gene and body FM in boys were only found in a healthy young population, but not in a comparable, generally leaner cohort from an older generation, it is suggested that carriers of this polymorphism are likely to be more vulnerable to fat accumulation in today's obesity promoting environment, than noncarriers.

Sex hormones and cognitive decline in elderly men.

Decline of cognitive function with age may be due, in part, to hormonal changes and it has been hypothesized that higher levels of endogenous sex hormones preserve brain function. The aim of this prospective cohort study was to determine the relative contribution of endogenous sex hormones to cognitive decline in a population-based sample of 242 elderly men aged 73-91 at baseline. Endogenous sex hormone levels were measured at baseline and participants underwent a cognitive assessment at baseline and at follow-up after 4 years. Higher estradiol (total and bioavailable) and estrone levels were associated with an increased risk of cognitive decline in elderly men independent of age, cardiovascular risk factors, atherosclerosis, and APOE genotype. These findings do not support the hypotheses that higher levels of endogenous sex hormones preserve brain function.

Potential role of type I interferons in the treatment of pituitary adenomas.

Cytokines, particularly those endowed with pro-inflammatory properties, are known to influence the release of anterior pituitary hormones by a direct and indirect action at the level of pituitary gland and hypothalamus. Type I interferons (IFNs) represent a group of cytokines that act through a common receptor composed by two chains (IFNAR-1 and IFNAR-2). Several in vitro and in vivo studies underline the fact that type I IFNs are involved in the regulation of the immune-endocrine circuitry. Treatment with type I IFNs of patients affected by chronic viral hepatitis, multiple sclerosis and tumors influences the secretion of pituitary hormones. This article reviews the current knowledge about the effects of IFN-alpha and IFN-beta on hypothalamic-pituitary function and describes the potential role of type I IFNs in the treatment of pituitary adenomas.

Effect of glucocorticoid receptor gene polymorphisms in Guillain-Barré syndrome.

Guillain-Barré syndrome (GBS) is a postinfectious immune-mediated polyneuroradiculopathy in which host factors influence disease susceptibility and clinical course. Single-nucleotide polymorphisms (SNPs) in the glucocorticoid receptor (GR) gene influence the sensitivity to glucocorticoids and are related to both microbial colonization and susceptibility to develop auto-immune disease. This genetic variation may therefore also influence the chance to develop GBS. In this study, we genotyped 318 GBS patients and 210 control subjects for five known SNPs in the GR gene. We could distinguish six different GR haplotypes of which two carried the BclI polymorphism: haplotype 1, which consists of the minor allele of BclI in combination with the common variant of TthIIII and haplotype 2, which carries the minor allele of BclI as well as the minor allele of TthIIII. The GR haplotypes were not related to susceptibility to develop GBS. Carriers of haplotype 2 had more frequently preceding diarrhea, serum antibodies to GM1 and GD1a, and more severe muscle weakness at entry. Haplotype 1 carriers had a significantly better prognosis. In conclusion, GR haplotypes are not a susceptibility factor for GBS. However, haplotypes carrying the minor allele of the BclI polymorphism were related to the phenotype and outcome of GBS.

Glucocorticoid receptor gene polymorphism is less frequent in children born small for gestational age without catch-up growth.

BACKGROUND/AIMS: Glucocorticoids are important regulators of many processes involved in embryonal growth and development and fat and glucose metabolism. Glucocorticoids exert their effect through the glucocorticoid receptor (GR). The aim of this study was to investigate possible associations between 4 well-known GR gene haplotypes and size at birth. METHODS: We investigated associations between GR haplotypes and size at birth in a Dutch reference cohort. This reference cohort consisted of 222 young healthy Caucasian subjects. Associations between size at birth and glucocorticoid receptor gene haplotypes were tested. Furthermore, we investigated a group of 119 children born small for gestational age (SGA), without catch-up growth. Prevalence of the different GR haplotypes was compared between the SGA group and the reference cohort. RESULTS: No associations were found between any of the GR haplotypes and birth weight or birth length in the reference group. The prevalence of GR haplotype 2 (Bcl1) was significantly lower in the SGA group compared to controls. CONCLUSION: Genetic variance in the GR seems not to be associated with intrauterine growth in the general population. However, GR haplotype might play a role in growth of children born SGA, reflected by the decreased prevalence of GR haplotype 2 (Bcl1) in this group.

Future treatment strategies of aggressive pituitary tumors.

While surgery remains the first-line treatment of most aggressive pituitary adenomas, medical therapy is important as second-line or adjunctive therapy in a large proportion of patients. Dopamine agonists (DAs) are the best treatment for prolactinomas, but when DAs are not tolerated, new somatostatin receptor subtype 5 (SSTR(5)) inhibitors may offer an alternative in the future. Unfortunately, these are unlikely to be effective in DA-resistant prolactinomas. In acromegaly, the existing somatostatin analogs, octreotide and lanreotide, will remain the medical treatment of choice for the foreseeable future. There is an urgent need for medical therapies in Cushing's disease, and the SSTR(5) analogs could offer an effective treatment in a proportion of patients within the next few years. Finally, the medical management options for non-functioning pituitary adenomas are also very limited, and a new chimeric agent with activity towards dopamine receptors, SSTR(5) and SSTR(2) may help reduce adenoma recurrence in the future.

BclI glucocorticoid receptor polymorphism and smoking in the general population.

We studied the hypothesis that the BclI polymorphism of the glucocorticoid receptor gene is associated with an increased probability of being a (heavy) smoker and a decreased ability to quit smoking. The study cohort consisted of all subjects in the Rotterdam Study, a Dutch population-based cohort of people aged 55 years and older, for whom BclI genotyping and smoking status at baseline were available. In prospective analyses, the smoking status was reassessed during three additional examination rounds. Logistic regression analysis was used to study the association between BclI polymorphism and being a smoker or a heavy smoker at baseline. Furthermore, the relationship between BclI polymorphism and incident smoking cessation was tested with Cox proportional hazards analysis within those who smoked at baseline. In total, 6358 subjects were included in the study. The presence of a G-allele was not associated with current smoking at baseline [odds ratio (OR) = 0.96, 95%confidence interval (CI): 0.85-1.09] or with the incidence of smoking cessation during follow-up [hazard ratio (HR) = 0.98, 95%CI: 0.80-1.19]. Within current smokers, having a G-allele was not significantly associated with the risk of being a heavy smoker when measured by pack-years smoked (OR = 1.07, 95%CI: 0.85-1.35) or daily consumption of tobacco (OR = 1.10, 95%CI: 0.88-1.37). We were not able to replicate the earlier findings indicating that the proportion of current smokers is lower among carriers of the CC-genotype of the BclI glucocorticoid receptor. Furthermore, the BclI glucocorticoid receptor polymorphism did not predict the incidence of smoking cessation in the general elderly population.

Glucocorticoid receptor gene and risk of cardiovascular disease.

BACKGROUND: Genetic variants in immunomodulating genes have been suggested to contribute to the risk of cardiovascular disease. Glucocorticoids are important regulators of inflammatory processes and the immune system. Our aim was to determine the contribution of genetic glucocorticoid receptor variants, with different cortisol sensitivities, to the risk of cardiovascular disease. METHODS: The study was conducted in a large (n=7983) population-based, prospective cohort of the Rotterdam Study. The mean duration of follow-up was 8.9 years. Measures of cardiovascular disease were incident myocardial infarction, coronary heart disease, high-sensitivity C-reactive protein level, interleukin 6 level, and arteria carotis intima-media thickness. RESULTS: Persons homozygous for haplotype 3, which is a common variant of the glucocorticoid receptor gene, had a more than 2-fold increased risk of myocardial infarction (hazard ratio, 2.1; 95% confidence interval, 1.13-4.07) and an almost 3-fold increased risk of coronary heart disease (hazard ratio, 2.6; 95% confidence interval, 1.40-4.81) compared with nonhomozygous persons. In addition, their C-reactive protein and interleukin 6 levels were higher, and carotis intima-media thickness was greater. No associations were found for the other haplotypes. CONCLUSIONS: The glucocorticoid receptor gene haplotype 3 is a common genetic variant and is related to a more active proinflammatory system. This haplotype is associated with the risk of cardiovascular disease and its parameters. These results should be regarded as hypothesis generating until they have been replicated in other studies. Our findings suggest that genetically determined cortisol sensitivity is involved in the pathogenesis of cardiovascular disease and might identify a subgroup at risk.

ANNIVERSARY REVIEW: Octreotide, 40 years later.

Octreotide remains 40 years after its development a drug, which is commonly used in the treatment of acromegaly and GEP-NETs. Very little innovation that competes with this drug occurred over this period. This review discusses several aspects of 40 years of clinical use of octreotide, including the application of radiolabeled forms of the peptide.

Correlation of in vitro and in vivo somatotropic adenoma responsiveness to somatostatin analogs and dopamine agonists with immunohistochemical evaluation of somatostatin and dopamine receptors and electron microscopy.

OBJECTIVE AND PATIENTS: Twenty-four pituitary adenomas from acromegalic patients (13 females, 11 males; age range 19-65 yr) were characterized for somatostatin receptor subtype 2A (sst(2A)), dopamine D(2) receptor (D(2)R), GH, and prolactin (PRL) expression by immunohistochemistry, and results correlated with the in vitro and in vivo hormone responses to octreotide and quinagolide. In nine cases, GH and PRL content was further studied by immunoelectron microscopy. RESULTS: Immunoreactivity was semiquantitatively scored as 2 (>50% stained cells), 1 (10-50% stained cells), and 0 (<10% stained cells). Sst(2A) was scored as 2 in 13 cases, 1 in 10, and 0 in one; D(2)R was scored as 2 in 13 cases, 1 in nine, and 0 in 2; GH was 2 in 15 cases and 1 in nine; PRL was 2 in six cases, 1 in 13, and 0 in 5. Sst(2A) was positively correlated with in vitro (P = 0.003) and in vivo (P = 0.006) percent GH suppression by octreotide and with the chronic suppression of IGF-I by somatostatin analogs (P =0.008). D(2)R was positively correlated with in vitro percent GH (P =0.000) and PRL (P =0.005) suppression by quinagolide. Electron microscopy revealed two pure somatotroph adenomas, five somatomammotrophs with a variable coexpression of GH and PRL in the same cells, and two tumors consisting of mixed cell types, which were less sensitive to quinagolide and octreotide. CONCLUSION: Sst(2A) and D(2)R are frequently coexpressed in adenomas from acromegalic patients, and immunohistochemistry may be helpful in characterizing receptor expression in pituitary adenomas to select patients responsive to different treatments.

Normal values of circulating insulin-like growth factor-I bioactivity in the healthy population: comparison with five widely used IGF-I immunoassays.

BACKGROUND: IGF-I immunoassays are primarily used to estimate IGF-I bioactivity. Recently an IGF-I-specific kinase receptor activation assay (KIRA) has been developed as an alternative method. However, no normative values have been established for the IGF-I KIRA. OBJECTIVE: The objective of the study was to establish normative values for the IGF-I KIRA in healthy adults. DESIGN: This was a cross-sectional study in healthy nonfasting blood donors. STUDY PARTICIPANTS: Participants included 426 healthy individuals (310 males, 116 females; age range 18-79 yr). MAIN OUTCOME MEASURES: IGF-I bioactivity determined by the KIRA was measured. Results were compared with total IGF-I, measured by five different IGF-I immunoassays. RESULTS: Mean (+/- sd) IGF-I bioactivity was 423 (+/- 131) pmol/liter and decreased with age (beta = -3.4 pmol/liter.yr, P < 0.001). In subjects younger than 55 yr, mean IGF-I bioactivity was significantly higher in women than men. Above this age this relationship was inverse, suggesting a drop in IGF-I bioactivity after menopause. This drop was not reflected in total IGF-I levels. IGF-I bioactivity was significantly related to total IGF-I (r(s) varied between 0.46 and 0.52; P < 0.001). CONCLUSIONS: We established age-specific normative values for the IGF-I KIRA. We observed a significant drop in IGF-I bioactivity in women between 50 and 60 yr, which was not perceived by IGF-I immunoassays. The IGF-I KIRA, when compared with IGF-I immunoassays, theoretically has the advantage that it measures net effects of IGF-binding proteins on IGF-I receptor activation. However, it has to be proven whether information obtained by the IGF-I KIRA is clinically more relevant than measurements obtained by IGF-I immunoassays.

Two common haplotypes of the glucocorticoid receptor gene are associated with increased susceptibility to cardiovascular disease in men with familial hypercholesterolemia.

CONTEXT: Glucocorticoids contribute to the development of atherosclerosis. Four polymorphisms in the glucocorticoid receptor (GR) gene have been reported to alter glucocorticoid sensitivity and have been associated with cardiovascular risk factors. Studies on the relationship between these GR variants and cardiovascular disease (CVD) risk, however, have yielded conflicting results. OBJECTIVE: We sought to determine whether haplotypes based on functional polymorphisms in the GR gene influenced susceptibility to CVD in a high-risk population. DESIGN, SETTING, AND PARTICIPANTS: In a multicenter cohort study, 1830 patients with heterozygous familial hypercholesterolemia were genotyped for the functional ER22/23EK, N363S, BclI, and 9beta variants. We analyzed the combined effect of all GR variants by constructing haplotypes and using a Cox proportional hazards regression model with adjustment for year of birth and smoking. The analyses were stratified for sex. MAIN OUTCOME MEASURES: The primary outcome measure was CVD defined as coronary, cerebral, and peripheral artery disease. RESULTS: A total of 359 men (40.8%) and 224 women (23.6%) had a cardiovascular event. In men, the BclI haplotype was associated with a 34% higher CVD risk (confidence interval 1.02-1.76; P = 0.03) and the 9beta haplotype with a 41% higher CVD risk (confidence interval 1.02-1.94; P = 0.04). In women, none of the GR haplotypes was significantly related with CVD. We did not find differences in cardiovascular risk factors between GR haplotypes. CONCLUSIONS: In this large cohort of high-risk individuals, two common haplotypes in the GR gene modified CVD susceptibility among men.

The pathophysiological consequences of somatostatin receptor internalization and resistance.

Somatostatin receptors expressed on tumor cells form the rationale for somatostatin analog treatment of patients with somatostatin receptor-positive neuroendocrine tumors. Nevertheless, although somatostatin analogs effectively control hormonal hypersecretion by GH-secreting pituitary adenomas, islet cell tumors, and carcinoid tumors, significant differences are observed among patients with respect to the efficacy of treatment. This may be related to a differential expression of somatostatin receptor subtypes among tumors. In addition, the property of somatostatin receptor subtypes to undergo agonist-induced internalization has important consequences for visualizing, as well as for therapy, of receptor-positive tumors using radioisotope- or chemotherapeutic-compound-coupled somatostatin analogs. This review covers the pathophysiological role of somatostatin receptor subtypes in determining the efficacy of treatment of patients with somatostatin receptor-positive tumors using somatostatin analogs, as well as the preclinical and clinical consequences of agonist-induced receptor internalization for somatostatin receptor-targeted radio- and chemotherapy. Herein, the development and potential role of novel somatostatin analogs is discussed.

Ficoll-separated mononuclear cells from sepsis patients are contaminated with granulocytes.

OBJECTIVE: To determine the cell content and purity of Ficoll-separated peripheral blood mononuclear cells and granulocyte isolates in sepsis patients compared to healthy controls. DESIGN AND SETTING: Prospective study in the adult and pediatric intensive care departments of the Erasmus University Medical Center in the Netherlands. PATIENTS: Three sepsis patients (two adults, one child) and four healthy controls. MEASUREMENTS AND RESULTS: Blood leukocytes were separated by Ficoll into an interface and a bottom fraction. The cell content and purity was analyzed by cytospin and flow-cytometric immunofluorescence. In sepsis patients, the interface consisted of 11-52% mononuclear cells only, due to high contamination with granulocytes (48-89%). This was in contrast to a high proportion of mononuclear cells (88-100%) in healthy controls. The bottom fraction showed a cell purity of >or=92% polymorphonuclear granulocytes in sepsis patients as well as in healthy controls. CONCLUSIONS: Ficoll-separated leukocytes of sepsis patients are not suitable for studying mononuclear cells but can be used for studying granulocytes with high purity. The mononuclear cell fraction is highly contaminated with granulocytes. Additional separation techniques are necessary to obtain a pure cell fraction.