Prenatal exposure to bisphenol A and/or diethylhexyl phthalate alters stress responses in rat offspring in a sex- and dose-dependent manner

Background: Prenatal exposures to endocrine disrupting chemicals (EDCs) are correlated with adverse behavioral outcomes, but the effects of combinations of these chemicals are unclear. The aim of this study was to determine the dose-dependent effects of prenatal exposure to EDCs on male and female behavior. Methods: Pregnant Sprague-Dawley rats were orally dosed with vehicle, bisphenol A (BPA) (5 μg/kg body weight (BW)/day), low-dose (LD) diethylhexyl phthalate (DEHP) (5 μg/kg BW/day), high-dose (HD) DEHP (7.5 mg/kg BW/day), a combination of BPA and LD-DEHP (B + D (LD)), or a combination of BPA and HD-DEHP (B + D (HD)) on gestational days 6-21. Adult offspring were subjected to the Open Field Test (OFT), Elevated Plus Maze (EPM), and Shock Probe Defensive Burying test (SPDB) in adulthood. Body, adrenal gland, and pituitary gland weights were collected at sacrifice. Corticosterone (CORT) was measured in the serum. Results: Female EDC-exposed offspring showed anxiolytic effects in the OFT, while male offspring were unaffected. DEHP (HD) male offspring demonstrated a feminization of behavior in the EPM. Most EDC-exposed male offspring buried less in the SPDB, while their female counterparts showed reduced shock reactivity, indicating sex-specific maladaptive alterations in defensive behaviors. Additionally, DEHP (LD) males and females and B + D (LD) females displayed increased immobility in this test. DEHP (LD) alone and in combination with BPA led to lower adrenal gland weights, but only in male offspring. Finally, females treated with a mixture of B + D (HD) had elevated CORT levels. Conclusion: Prenatal exposure to BPA, DEHP, or a mixture of the two, affects behavior, CORT levels, and adrenal gland weights in a sex- and dose-dependent manner.

Assessment of factual recall and higher-order cognitive domains in an open-book medical school examination

Open-book examinations (OBEs) will likely become increasingly important assessment tools. We investigated how access to open-book resources affected questions testing factual recall, which might be easy to look-up, versus questions testing higher-order cognitive domains. Few studies have investigated OBEs using modern Internet resources or as summative assessments. We compared performance on an examination conducted as a traditional closed-book exam (CBE) in 2019 (N = 320) and a remote OBE with free access to Internet resources in 2020 (N = 337) due to COVID-19. This summative, end-of-year assessment focused on basic science for second-year medical students. We categorized questions by Bloom's taxonomy ('Remember', versus 'Understand/Apply'). We predicted higher performance on the OBE, driven by higher performance on 'Remember' questions. We used an item-centric analysis by using performance per item over all examinees as the outcome variable in logistic regression, with terms 'Open-Book, 'Bloom Category' and their interaction. Performance was higher on OBE questions than CBE questions (OR 2.2, 95% CI: 2.14-2.39), and higher on 'Remember' than 'Understand/Apply' questions (OR 1.13, 95% CI: 1.09-1.19). The difference in performance between 'Remember' and 'Understand/Apply' questions was greater in the OBE than the CBE ('Open-Book' * 'Bloom Category' interaction: OR 1.2, 95% CI: 1.19-1.37). Access to open-book resources had a greater effect on performance on factual recall questions than higher-order questions, though performance was higher in the OBE overall. OBE design must consider how searching for information affects performance, particularly on questions measuring different domains of knowledge.

Comparison of the utility of Cocaine- and Amphetamine-Regulated Transcript (CART), chromogranin A, and chromogranin B in neuroendocrine tumor diagnosis and assessment of disease progression

CONTEXT

Prognosis in patients with neuroendocrine tumors (NETs) is often poor, frequently reflecting delayed diagnosis. Hence, accurate and practical NET markers are needed. Cocaine- and amphetamine-regulated transcript (CART) peptide is a potential novel NET marker.

DESIGN AND PARTICIPANTS

Circulating levels of CART peptide and the established NET markers chromogranin A (CgA) and chromogranin B (CgB) were measured using RIA in 353 patients with NET (normal renal function) and in controls. Clinical data were collected retrospectively.

MAIN OUTCOME MEASURE(S)

The comparative and combined utility of CART, CgA, and CgB for diagnosis and assessment of disease progression was measured in different NET subtypes.

RESULTS

CgA and CgB in combination improved diagnostic accuracy in patients with gut NETs, nongastroenteropancreatic NETs, and NETs with an unknown primary origin compared with each biomarker alone. Measuring CART did not further improve diagnosis in these NET subtypes. For pancreatic NETs, CgB was superior to CgA and CART in detecting stable disease (P < .007), whereas CgA and CART in combination were most effective in identifying progressive disease. In phaeochromocytomas/paragangliomas (PCC/PGL), CART was the most useful biomarker for identifying stable (P < .001) and progressive (P = .001) disease. Consistent with this, plasma CART decreased following PCC/PGL tumor resection, remaining low in all patients in remission, but increasing in those with progressive disease.

CONCLUSIONS

CART is a useful marker for identifying progressive pancreatic NETs. CART is superior to CgA and CgB in detecting stable and progressive PCC/PGLs, and may have a role as a surveillance marker for PCC/PGL patients.

L-cysteine suppresses ghrelin and reduces appetite in rodents and humans

BACKGROUND

High-protein diets promote weight loss and subsequent weight maintenance, but are difficult to adhere to. The mechanisms by which protein exerts these effects remain unclear. However, the amino acids produced by protein digestion may have a role in driving protein-induced satiety.

METHODS

We tested the effects of a range of amino acids on food intake in rodents and identified l-cysteine as the most anorexigenic. Using rodents we further studied the effect of l-cysteine on food intake, behaviour and energy expenditure. We proceeded to investigate its effect on neuronal activation in the hypothalamus and brainstem before investigating its effect on gastric emptying and gut hormone release. The effect of l-cysteine on appetite scores and gut hormone release was then investigated in humans.

RESULTS

l-Cysteine dose-dependently decreased food intake in both rats and mice following oral gavage and intraperitoneal administration. This effect did not appear to be secondary to behavioural or aversive side effects. l-Cysteine increased neuronal activation in the area postrema and delayed gastric emptying. It suppressed plasma acyl ghrelin levels and did not reduce food intake in transgenic ghrelin-overexpressing mice. Repeated l-cysteine administration decreased food intake in rats and obese mice. l-Cysteine reduced hunger and plasma acyl ghrelin levels in humans.

CONCLUSIONS

Further work is required to determine the chronic effect of l-cysteine in rodents and humans on appetite and body weight, and whether l-cysteine contributes towards protein-induced satiety.

A high pressure x-ray photoelectron spectroscopy study of CO oxidation over Rh(100)

We have studied the oxidation of CO over Rh(100) using high pressure x-ray photoelectron spectroscopy under CO and O2 pressures ranging from 0.01 to 1 mbar. The results show a very low or no conversion for the CO covered surface found at low temperatures, while the activity rises slightly when the temperature is high enough for some CO to desorb, exposing surface sites for dissociative O2 adsorption. As the temperature is increased further, more CO desorbs and oxygen replaces CO as the dominating species at the surface. At the same time we find a sudden increase in the reactivity, such that all CO that reaches the surface is instantly transformed into CO2. We find that the O coverage in the active state is highly dependent on the total pressure and, although we do not detect any presence of a surface oxide as in previous surface x-ray diffraction studies, the highest O coverage indicates that the surface is close to being oxidized.

Hepcidin levels in diabetes mellitus and polycystic ovary syndrome

AIM

Increased body iron is associated with insulin resistance. Hepcidin is the key hormone that negatively regulates iron homeostasis. We hypothesized that individuals with insulin resistance have inadequate hepcidin levels for their iron load.

METHODS

Serum concentrations of the active form of hepcidin (hepcidin-25) and hepcidin:ferritin ratio were evaluated in participants with Type 2 diabetes (n = 33, control subjects matched for age, gender and BMI, n = 33) and participants with polycystic ovary syndrome (n = 27, control subjects matched for age and BMI, n = 16). To investigate whether any changes observed were associated with insulin resistance rather than insulin deficiency or hyperglycaemia per se, the same measurements were made in participants with Type 1 diabetes (n = 28, control subjects matched for age, gender and BMI, n = 30). Finally, the relationship between homeostasis model assessment of insulin resistance and serum hepcidin:ferritin ratio was explored in overweight or obese participants without diabetes (n = 16).

RESULTS

Participants with Type 2 diabetes had significantly lower hepcidin and hepcidin:ferritin ratio than control subjects (P < 0.05 and P < 0.01, respectively). Participants with polycystic ovary syndrome had a significantly lower hepcidin:ferritin ratio than control subjects (P < 0.05). There was no significant difference in hepcidin or hepcidin:ferritin ratio between participants with Type 1 diabetes and control subjects (P = 0.88 and P = 0.94). Serum hepcidin:ferritin ratio inversely correlated with homeostasis model assessment of insulin resistance (r = -0.59, P < 0.05).

CONCLUSION

Insulin resistance, but not insulin deficiency or hyperglycaemia per se, is associated with inadequate hepcidin levels. Reduced hepcidin concentrations may cause increased body iron stores in insulin-resistant states.

The biochemical utility of chromogranin A, chromogranin B and cocaine- and amphetamine-regulated transcript for neuroendocrine neoplasia

Neuroendocrine neoplasia (NEN) is a heterogeneous group of tumours and often represents a therapeutic challenge to clinicians. The peptides chromogranin A (CgA), chromogranin B (CgB) and cocaine- and amphetamine-regulated transcript (CART) are widely distributed throughout the neuroendocrine system. CgA and CgB have been used as general NEN biomarkers for many years, while CART has only recently been identified. Of these biomarkers, CgA is the most commonly used. However, circulating CgA concentrations exhibit considerable intra-individual biological variation, are altered by proton pump inhibitors (PPIs) and somatostatin analogues and are elevated in non-NEN malignancies. Therefore, interpretation of CgA results must be in the context of these confounding factors. The effects of treatment and non-NEN conditions on circulating CgB and CART concentrations are less well understood. CgB is less affected by impaired renal function and PPIs than CgA; while, circulating CART concentrations lack a diurnal variation in humans and are more reliable markers of pancreatic NEN malignancy than CgA. The utility of circulating CgA measurements in NEN prognosis, surveillance and disease recurrence has been widely investigated. However, the utility of CgB and CART in NEN management is yet to be elucidated. Further studies are needed to establish whether CgB and CART are useful alternatives to CgA.

In situ x-ray photoelectron spectroscopy of model catalysts: at the edge of the gap

We present high-pressure x-ray photoelectron spectroscopy (HP-XPS) and first-principles kinetic Monte Carlo study addressing the nature of the active surface in CO oxidation over Pd(100). Simultaneously measuring the chemical composition at the surface and in the near-surface gas phase, we reveal both O-covered pristine Pd(100) and a surface oxide as stable, highly active phases in the near-ambient regime accessible to HP-XPS. Surprisingly, no adsorbed CO can be detected during high CO(2) production rates, which can be explained by a combination of a remarkably short residence time of the CO molecule on the surface and mass-transfer limitations in the present setup.

Glucagon and GLP-1 inhibit food intake and increase c-fos expression in similar appetite regulating centres in the brainstem and amygdala

BACKGROUND

Glucagon and glucagon-like peptide-1 (GLP-1) are evolutionarily related anorectic hormones. Glucagon also increases energy expenditure. The combination of glucagon and GLP-1 could cause weight loss through a simultaneous reduction in food intake and increased energy expenditure. However, the effect of combined administration of glucagon and GLP-1 on food intake and neuronal activation has not previously been studied. Furthermore, the effect of glucagon on neuronal activation in appetite regulating centres has not been assessed. Characterisation of the effects of glucagon when administered singly and in combination with GLP-1 on neuronal activation will be important for determining the mechanism of action of related potential antiobesity therapies.

OBJECTIVES

To investigate the effects of peripherally administered GLP-1 and glucagon on food intake, neuronal activation and blood glucose in mice when administered individually and in combination.

METHODOLOGY

Food intake, blood glucose and c-fos expression in the hypothalamus, amygdala and brainstem were measured in response to GLP-1 and glucagon, alone and in combination.

RESULTS

Peripherally administered GLP-1 and glucagon decreased food intake and increased c-fos expression in the brainstem and amygdala. Doses of GLP-1 and glucagon that individually did not significantly affect feeding, in combination were anorectic and stimulated neuronal activation in the area postrema (AP) and central nucleus of the amygdala. Combined administration of GLP-1 and glucagon prevented the acute hyperglycemic effect of glucagon alone.

CONCLUSION

Anorectic doses of glucagon and GLP-1 induced similar patterns of c-fos expression. Combined administration of low dose GLP-1 and glucagon inhibited food intake and induced c-fos expression in the AP and amygdala. The combination of both hormones may offer the opportunity to utilise the beneficial effects of reduced food intake and increased energy expenditure, and may therefore be a potential treatment for obesity.

A comparison of the performance of ⁶⁸Ga-DOTATATE PET/CT and ¹²³I-MIBG SPECT in the diagnosis and follow-up of phaeochromocytoma and paraganglioma

PURPOSE

To compare the sensitivity of (123)I-metaiodobenzylguanidine (MIBG) SPECT and (68)Ga-DOTATATE PET/CT in detecting phaeochromocytomas (PCC) and paragangliomas (PGL) in the initial diagnosis and follow-up of patients with PCC and PGL disease.

METHODS

Retrospective analysis of 15 patients with PCC/PGL who had contemporaneous (123)I-MIBG and (68)Ga-DOTATATE imaging.

RESULTS

Of the 15 patients in the series, 8 were concordant with both modalities picking up clinically significant lesions. There were no patients in whom both modalities failed to pick up clinically significant lesions. There was discordance in seven patients: 5 had positive (68)Ga-DOTATATE and negative (123)I-MIBG, and 2 (12 and 14) had negative (68)Ga-DOTATATE and positive (123)I-MIBG. Utilizing (123)I-MIBG as the gold standard, (68)Ga-DOTATATE had a sensitivity of 80 % and a positive predictive value of 62 %. The greatest discordance was in head and neck lesions, with the lesions in 4 patients being picked up by (68)Ga-DOTATATE and missed by (123)I-MIBG. On a per-lesion analysis, cross-sectional (CT and MRI) and (68)Ga-DOTATATE was superior to (123)I-MIBG in detecting lesions in all anatomical locations, and particularly bony lesions.

CONCLUSION

First, (68)Ga-DOTATATE should be considered as a first-line investigation in patients at high risk of PGL and metastatic disease, such as in the screening of carriers for mutations associated with familial PGL syndromes. Second, if (123)I-MIBG does not detect lesions in patients with a high pretest probability of PCC or PGL, (68)Ga-DOTATATE should be considered as the next investigation. Third, (68)Ga-DOTATATE hould be considered in preference to (123)I-MIBG in patients in whom metastatic spread, particularly to the bone, is suspected.

Effective combination treatment with cabergoline and low-dose pegvisomant in active acromegaly: a prospective clinical trial

CONTEXT

With adequate dose titration, pegvisomant normalizes IGF-I in up to 97% of patients with acromegaly. Pegvisomant is indicated for treatment-resistant disease but is expensive, particularly at a high dose. It has been used successfully in combination with somatostatin analogs. However, there are no therapeutic reports of pegvisomant in combination with dopamine agonists. Cabergoline is orally active, well-tolerated, and relatively inexpensive, and as monotherapy for acromegaly it is reported to normalize IGF-I in up to 30% of patients.

OBJECTIVE

The aim of the study was to investigate the efficacy of cabergoline monotherapy and pegvisomant in combination with cabergoline to control serum IGF-I in patients with active acromegaly. Twenty-four patients were recruited into a United Kingdom, multicenter, open-label, prospective clinical trial.

MAIN OUTCOME MEASURE

We measured the change in serum IGF-I.

RESULTS

After 18 wk of dose titration to a maximum dose of 0.5 mg once daily, cabergoline monotherapy did not significantly reduce IGF-I (454 ± 219 baseline vs. 389 ± 192 ng/ml cabergoline), although two patients did normalize IGF-I. The addition of 10 mg pegvisomant daily for 12 wk significantly reduced IGF-I (389 ± 192 ng/ml cabergoline vs. 229 ± 101 ng/ml combination), and 68% achieved a normal IGF-I. Twelve weeks after cabergoline withdrawal, while continuing to receive pegvisomant 10 mg, only 26% of patients maintained an IGF-I within the reference range (229 ± 101 ng/ml combination vs. 305 ± 177 ng/ml pegvisomant). There were no significant changes in liver transaminases or glucose metabolism throughout the study.

CONCLUSION

These data suggest that combination treatment with cabergoline and pegvisomant is more effective at reducing IGF-I levels than either cabergoline or pegvisomant monotherapy.

The Active Phase of Palladium during Methane Oxidation

The active phase of Pd during methane oxidation is a long-standing puzzle, which, if solved, could provide routes for design of improved catalysts. Here, density functional theory and in situ surface X-ray diffraction are used to identify and characterize atomic sites yielding high methane conversion. Calculations are performed for methane dissociation over a range of Pd and PdOx surfaces and reveal facile dissociation on either under-coordinated Pd sites in PdO(101) or metallic surfaces. The experiments show unambiguously that high methane conversion requires sufficiently thick PdO(101) films or metallic Pd, in full agreement with the calculations. The established link between high activity and atomic structure enables rational design of improved catalysts.

Low-dose oral tri-iodothyronine does not directly increase food intake in man

Previously, we have shown that low-dose tri-iodothyronine (T3) increases food intake in rodents. This randomised, double-blind, placebo-controlled study aimed to investigate the effects of low-dose T3 on food intake in normal body weight individuals. However, despite an elevation in fT3 comparable to our earlier studies, administration of low-dose T3 in the fasted state did not stimulate food intake in man.

Exploiting the DNA repair defect in BRCA mutant cells in the design of new therapeutic strategies for cancer

Individuals harboring germ-line mutations in the BRCA1 or BRCA2 genes are at highly elevated risk of a variety of cancers. Ten years of research has revealed roles for BRCA1 and BRCA2 in a wide variety of cellular processes. However, it seems likely that the function of these proteins in DNA repair is critically important in maintaining genome stability. Despite this increasing knowledge of the defects present in BRCA-deficient cells, BRCA mutation carriers developing cancer are still treated similarly to sporadic cases. Here we describe our efforts, based on understanding the DNA repair defects in BRCAdeficient cells, to define the optimal existing treatment for cancers arising in BRCA mutation carriers and, additionally, the development of novel therapeutic approaches. Finally, we discuss how therapies developed to treat BRCA mutant tumors might be applied to some sporadic cancers sharing similar specific defects in DNA repair.

Comparison of the dexamethasone-suppressed corticotropin-releasing hormone test and low-dose dexamethasone suppression test in the diagnosis of Cushing's syndrome

CONTEXT

The low-dose dexamethasone suppression test (LDDST) is widely used in confirming a diagnosis of Cushing's syndrome. CRH administration at the end of an LDDST has been reported to improve the diagnostic accuracy of this test.

OBJECTIVE

Our objective was to assess whether CRH administration after a standard LDDST (LDDST-CRH test) improves diagnostic accuracy in Cushing's syndrome.

DESIGN, SETTING, AND PARTICIPANTS

Thirty-six individuals with a clinical suspicion of Cushing's syndrome each completed a standard LDDST and an LDDST-CRH test at Hammersmith Hospitals NHS Trust, London. The LDDST involved administration of 0.5 mg oral dexamethasone given 6-hourly for 48 h. Serum cortisol was measured 6 h after the last dose of dexamethasone, with a value of 50 nmol/liter or below excluding Cushing's syndrome. Immediately after this, the LDDST-CRH test commenced with administration of a ninth dose of 0.5 mg dexamethasone. Exactly 2 h later, 100 mug human-sequence CRH was administered. Serum cortisol was measured 15 min after the CRH injection, with a value of less than 38 nmol/liter also excluding Cushing's syndrome.

MAIN OUTCOME MEASURE

Diagnosis or exclusion of Cushing's syndrome was the main outcome measure.

RESULTS

Twelve subjects were diagnosed with Cushing's syndrome (eight Cushing's disease and four primary adrenal). The sensitivity of the LDDST in diagnosing Cushing's syndrome was 100%, with a specificity of 88%. In contrast, although the sensitivity of the LDDST-CRH test was also 100%, specificity was reduced at 67%. These results give a positive predictive value of 80% for the LDDST and 60% for the LDDST-CRH test.

CONCLUSION

This small study suggests that the addition of CRH to the LDDST does not improve the diagnostic accuracy of the standard LDDST in Cushing's syndrome.

Plasma gastrin measurement cannot be used to diagnose a gastrinoma in patients on either proton pump inhibitors or histamine type-2 receptor antagonists

BACKGROUND

Patients with a gastrinoma are treated with proton pump inhibitors (PPI) and histamine type-2 receptor antagonists (H2). In order to diagnose a gastrinoma these drugs must be discontinued, but this increases the risk of gastrointestinal perforation. We aimed to determine if a gastrinoma could be diagnosed without cessation of PPI/H2 therapy.

METHODS

In all, 90 patients (controls and patients diagnosed with a gastrinoma both on and off PPI/H2 therapy) were recruited, and plasma gastrin measured.

RESULTS

Patients with a gastrinoma on PPI/H2 medication had a significantly higher fasting plasma gastrin concentration than control patients on PPI/H2 medication (298+/-33 versus 204+/-30 pmol/L, P = 0.01). However, there was substantial overlap between gastrin levels in these two groups.

CONCLUSION

This study confirms that a gastrinoma cannot be diagnosed on the basis of a fasting plasma gastrin assay while patients remain on PPI/H2 therapy.

Abnormalities of the somatotrophic axis in the obese agouti mouse

OBJECTIVE

Abnormalities of the melanocortin system produce obesity and increased linear growth. While the obesity phenotype is well characterised, the mechanism responsible for increased linear growth is unclear. The somatotrophic axis was studied in the obese agouti (A(y)/a) mouse as a model of a perturbed melanocortin system.

DESIGN

Adult obese A(y)/a mice were compared to age- and sex-matched wild-type (WT) controls. Weight and body length (nose-anus) were recorded. Plasma growth hormone (GH), insulin-like growth factor-I (IGFI), insulin and leptin were measured using radioimmunoassay. Since ghrelin is a potent GH secretagogue, plasma ghrelin, stomach ghrelin peptide and stomach ghrelin mRNA expression were studied. Hypothalamic periventricular (PeVN) somatostatin neurones and arcuate (Arc) neuropeptide Y (NPY) neurones inhibit the growth axis, whereas Arc growth hormone-releasing hormone (GHRH) neurones are stimulatory. Therefore, specific hypothalamic expression of somatostatin, NPY and GHRH was measured using quantitative in situ hybridisation.

RESULTS

Obese A(y)/a mice were significantly heavier and longer than WT controls. Plasma IGFI concentrations were 30% greater in obese A(y)/a mice. Obese A(y) /a mice were hyperinsulinaemic and hyperleptinaemic, yet plasma ghrelin, and stomach ghrelin peptide and mRNA were significantly reduced. In obese A(y)/a mice, PeVN somatostatin and Arc NPY mRNA expression were reduced by 50% compared to WT controls, whereas Arc GHRH mRNA expression was unchanged.

CONCLUSION

Increased body length in adult obese A(y)/a mice may result from reduced Arc NPY and PeVN somatostatin mRNA expression, which in turn, may increase plasma IGFI concentrations and upregulate the somatotrophic axis.

Ghrelin enhances gastric emptying in diabetic gastroparesis: a double blind, placebo controlled, crossover study

BACKGROUND

Diabetic gastroparesis is a disabling condition with no consistently effective treatment. In animals, ghrelin increases gastric emptying and reverses postoperative ileus. We present the results of a double blind, placebo controlled, crossover study of ghrelin in gastric emptying in patients with diabetic gastroparesis.

METHODS

Ten insulin requiring diabetic patients (five men, six type I) referred with symptoms indicative of gastroparesis received a two hour infusion of either ghrelin (5 pmol/kg/min) or saline on two occasions. Blood glucose was controlled by euglycaemic clamp. Gastric emptying rate (GER) was calculated by real time ultrasound following a test meal. Blood was sampled for ghrelin, growth hormone (GH), and pancreatic polypeptide (PP) levels. Cardiovagal neuropathy was assessed using the Mayo Clinic composite autonomic severity score (range 0 (normal)-3).

RESULTS

Baseline ghrelin levels were mean 445 (SEM 36) pmol/l. Ghrelin infusion achieved a peak plasma level of 2786 (188) pmol/l at 90 minutes, corresponding to a peak GH of 70.9 (19.8) pmol/l. Ghrelin increased gastric emptying in seven of 10 patients (30 (6)% to 43 (5)%; p = 0.04). Impaired cardiovagal tone correlated inversely with peak postprandial PP values (p < 0.05) but did not correlate with GER.

CONCLUSIONS

Ghrelin increases gastric emptying in patients with diabetic gastroparesis. This is independent of vagal tone. We propose that analogues of ghrelin may represent a new class of prokinetic agents.

Pre-obese and obese agouti mice are sensitive to the anorectic effects of peptide YY(3-36) but resistant to ghrelin

OBJECTIVE

The role of the melanocortin system in the feeding effects of peripheral peptide YY(3-36) (PYY(3-36)) and ghrelin was investigated using the agouti (A(y)/a) mouse as a model of abnormal melanocortin signalling. Furthermore, we examined whether the ectopic expression of agouti protein in A(y)/a mice results in complete MC4-R inhibition, by studying the effects of peripheral alpha-melanocyte-stimulating hormone (alpha-MSH) and leptin on food intake.

DESIGN

Adult A(y)/a mice were studied in the pre-obese state (7-8 weeks) and obese state (14-15 weeks). Animals received PYY(3-36) (0.02 micromol/kg), NDP-alpha-MSH (0.2 micromol/kg), leptin (2 micromol/kg) (all 24 h fasted state) and ghrelin (0.2 micromol/kg) (fed state) by intraperitoneal (i.p.) injection. Age-matched A(y)/a controls received i.p. saline. A separate cohort of wild-type (WT), age-matched controls received the same peptide dose or saline. Food intake was measured at 1, 2, 4, 8 and 24 h post-injection and compared in all four groups. Plasma leptin-, ghrelin- and PYY-like immunoreactivity (IR) were measured using radioimmunoassay (RIA).

RESULTS

At 2 h post-injection, PYY(3-36) reduced food intake in pre-obese and obese A(y)/a mice, whereas ghrelin had no effect. Plasma ghrelin levels were significantly reduced in pre-obese and obese A(y)/a mice compared to WT controls. Peripheral administration of NDP-alpha-MSH and leptin acutely suppressed feeding (0-2 h) in pre-obese and obese A(y)/a mice.

CONCLUSIONS

Responsiveness of pre-obese and obese A(y)/a mice to PYY(3-36) suggests that the melanocortin system may not be essential for the anorectic effects of this peptide. Melanocortinergic antagonism by agouti protein in A(y)/a mice may be sufficient to block the effects of endogenous, but not exogenous PYY(3-36), alpha-MSH and leptin. The mechanism underlying ghrelin resistance in A(y)/a mice may result from antagonism of hypothalamic melanocortin receptors-4 by agouti protein, supporting a role for the melanocortin system in mediating ghrelin's actions.

DNA repair inhibition and cancer therapy

The DNA repair process in mammalian cells is a multi-pathway mechanism that protects cells from the plethora of DNA damaging agents that are known to attack nuclear DNA. Moreover, the majority of current anticancer therapies (e.g. ionising radiation and chemotoxic therapies) rely on this ability to create DNA lesions, leading to apoptosis/cell death. A cells natural ability to repair such DNA damage is a major cause of resistance to these existing antitumour agents. It seems logical, therefore, that by modulating these repair mechanisms, greater killing effect to anticancer agents would occur. Experimental data support this, either through knockout studies or by the use of pharmacological inhibitors which target some of the key regulatory proteins involved in the DNA repair process. Several of these key DNA repair proteins which are actively under investigation as novel sites for intervention in cancer biology are discussed.

Amino acid sequence of CAP37, a human neutrophil granule-derived antibacterial and monocyte-specific chemotactic glycoprotein structurally similar to neutrophil elastase

We report the amino acid sequence of CAP37, a human neutrophil granule protein with antibacterial and monocyte-specific chemotactic activity. CAP37 is a single-chain protein consisting of 222 amino acid residues. It has three N-glycosylation sites, at Asn residues 100, 114 and 145. Some species of CAP37 are glycosylated at all three sites; some at Asn-114 alone, others at Asn-114 and Asn-110 or Asn-145. CAP37 has 45% sequence identity to human neutrophil elastase, and 30-37% identity to several other granule serine proteinases. Despite these similarities, CAP37 is not a serine proteinase because the active site residues serine and histidine are replaced.