The Emerging Role of Copeptin

Direct measurement of the nonapeptide vasopressin has been limited by analyte instability ex vivo and in vivo rapid degradation, low serum concentrations requiring a sensitive assay and inherent secretory pulsatility. Copeptin is a 39 amino acid glycopeptide cleavage product of vasopressin synthesis with high stability, providing a marker of vasopressin secretion. Copeptin measurement has applications in diagnosis of diabetes insipidus and other diseases with altered vasopressin secretion. This review summarises our current understanding of serum copeptin measurement in diabetes insipidus and possible future applications of copeptin assays. As vasopressin is a stress hormone, there is emerging evidence on the use of copeptin for diagnosis and prognostication of disorders such as syndrome of inappropriate anti-diuretic hormone secretion, diabetes mellitus, critical illness, stroke, cardiovascular disease, respiratory disease, renal disease and thermal stress. Copeptin concentration measurement is likely to improve the diagnostic reliability of diabetes insipidus and, as a marker of stress, may have diagnostic or prognostic utility in specific clinical circumstances. Further studies are needed to determine if goal-directed therapy using plasma copeptin concentrations may improve patient outcomes.

Acute Effects of Lixisenatide on Energy Intake in Healthy Subjects and Patients with Type 2 Diabetes: Relationship to Gastric Emptying and Intragastric Distribution

Glucagon-like peptide-1 receptor agonists induce weight loss, which has been suggested to relate to the slowing of gastric emptying (GE). In health, energy intake (EI) is more strongly related to the content of the distal, than the total, stomach. We evaluated the effects of lixisenatide on GE, intragastric distribution, and subsequent EI in 15 healthy participants and 15 patients with type 2 diabetes (T2D). Participants ingested a 75-g glucose drink on two separate occasions, 30 min after lixisenatide (10 mcg) or placebo subcutaneously, in a randomised, double-blind, crossover design. GE and intragastric distribution were measured for 180 min followed by a buffet-style meal, where EI was quantified. Relationships of EI with total, proximal, and distal stomach content were assessed. In both groups, lixisenatide slowed GE markedly, with increased retention in both the proximal (p < 0.001) and distal (p < 0.001) stomach and decreased EI (p < 0.001). EI was not related to the content of the total or proximal stomach but inversely related to the distal stomach at 180 min in health on placebo (r = -0.58, p = 0.03) but not in T2D nor after lixisenatide in either group. In healthy and T2D participants, the reduction in EI by lixisenatide is unrelated to changes in GE/intragastric distribution, consistent with a centrally mediated effect.

Diabetic Gastroparesis and Glycaemic Control

PURPOSE OF REVIEW

Gastroparesis is an important complication of diabetes that may have a major impact on the quality of life as a result of upper gastrointestinal symptoms and impaired glycaemic control. Current management strategies include optimising blood glucose control, dietary modifications and supportive nutrition. Pharmacologic approaches with drugs that have prokinetic and/or antiemetic effects are also used widely; however, current available treatments have major limitations. There is increasing recognition that the rate of gastric emptying (GE) is a key determinant of the glycaemic response to a meal.

RECENT FINDINGS

There is ongoing uncertainty regarding the impact of longstanding hyperglycaemia on GE, which requires clarification. New diagnostic techniques have been developed to better characterise the mechanisms underlying gastroparesis in individual patients, and these have the potential to lead to more personalised therapy. Management of gastroparesis is complex and suboptimal; novel approaches are desirable. This review summarises recent advances in the understanding of diabetic gastroparesis, with an emphasis on the current therapies that influence GE, and the bidirectional relationship between glycaemic control and GE.

Inhaled corticosteroids and secondary adrenal insufficiency

Inhaled corticosteroids (ICS) have been used as first line treatment of asthma for many decades. ICS are a form of exogenous glucocorticosteroids that can suppress the endogenous production of glucocorticosteroids, a condition known as adrenal suppression (AS). As a result, cessation, decreasing the dose or changing the type of ICS may trigger features of adrenal insufficiency (AI). AI may cause a spectrum of presentations varying from vague symptoms of fatigue to potentially life threatening acute adrenal crises. This article reviews the current literature on ICS and AI particularly in adults (although majority of data available is from the paediatric population). It aims to increase awareness of the potential risk of AI associated with ICS use, delineate the pathogenesis of AI and to provide recommendations on screening and management. From our literature review, we have found numerous case reports that have shown an association between ICS and AI particularly in children and patients using high doses. However, there have also been reports of AI in adults as well as in patients using low to moderate doses of ICS. To conclude, we recommend screening for AI in select patient groups with an initial early morning serum cortisol. If results are abnormal, more definitive testing such as the low dose corticotropin stimulation test may be done to confirm the diagnosis.

Screening for colorectal neoplastic lesions following acute diverticulitis: Would a sigmoidoscopy suffice?

AIM: To investigate the yield of colorectal malignant or premalignant lesions during colonoscopy performed following an episode of acute diverticulitis.

METHODS: A prospectively maintained electronic database of a public teaching hospital (Modbury Hospital, South Australia) was searched for international classification of diseases codes for acute diverticulitis from July 2007 to June 2011. The electronic database and each patient’s medical records were reviewed for demographic data, clinical presentation, investigation results, colonoscopy details and surgical intervention.

RESULTS: Two hundred and nineteen patients were diagnosed with acute diverticulitis with a median age of 60 years (range 24-93). One hundred and thirty-nine patients (63.5%) had follow-up screening colonoscopy, with the median interval between the episode of acute diverticulitis and colonoscopy being 8 wk (range: 1-66). Colonoscopy revealed polyps in 21 patients (15%) and no cases of colorectal cancer. Of the 21 patients with polyps, there were 14 patients (10%) with tubular/villous adenomas (13 in rectosigmoid region and 1 in descending colon).

CONCLUSION: Detection of colorectal cancer in patients undergoing routine colonoscopy following acute diverticulitis is rare. However, colonic polyps in the left colon are noted. A flexible sigmoidoscopy is an adequate screening tool in such patients. A complete colonoscopy reserved for patients with family history of colorectal cancer or with polyps detected on flexible sigmoidoscopy to evaluate the rest of the colon.

Expression of heat shock proteins in chronic pancreatitis: protective or pathogenic roles?

The tissue-distributions of heat shock proteins (HSP) identified by monoclonal antibodies ML-30, TB-78, CA-Str7-1, and MAB 72/73 have been examined in formalin-fixed and paraffin wax-embedded tissues from 10 normal pancreatic specimens and 92 cases of chronic pancreatitis. The chronic pancreatitis cases were divided by probable etiology into alcohol-related, postacute pancreatitis, or idiopathic. The HSP identified by ML-30 and CA-Str7-1 were constitutively expressed, with a regional distribution, by duct and ductular epithelial cells in all normal pancreatic tissues. The HSP detected by ML-30 were expressed uniformly throughout the cytoplasm of the majority of ductular epithelial cells in all cases of chronic pancreatitis, irrespective of suspected etiology, and in the ducts of all but two cases of alcohol-associated chronic pancreatitis. The HSP defined by CA-Str7-1 were identified in the majority of duct or ductular epithelial cells in most of the cases of chronic pancreatitis, although possible differential expression was observed with respect to etiology (ie, there seemed to be less HSP in cases of postalcohol pancreatitis). The HSP identified by TB-78 were not constitutively expressed by normal pancreatic tissues but were found in a few scattered epithelial cells in two of these cases. However, significant expression of these HSP were observed in most epithelial cells in a population of cases regarded as either alcohol-associated (0.05 > p > 0.02) or postacute chronic pancreatitis (0.01 > p > 0.001). The HSP identified by monoclonal antibody MAB 72/73 were either not demonstrable or were expressed at very low levels in both the normal and inflamed pancreatic tissues. Expression of the four groups of HSP molecules appeared to be differentially regulated both in normal pancreatic and in chronic pancreatitis tissues. These differences in expression may indicate different functions in normal tissues, with either a protective or a pathogenic role for these proteins in the diseased state. Our current findings support the hypothesis that expression of certain HSP, particularly those identified by TB-78, may be involved in the pathogenesis of distinct subtypes of chronic pancreatitis. Our data do not suggest that HSP are the primary targets of immune-mediated cytotoxic activity; nevertheless, enhanced expression of these molecules by pancreatic ductular epithelial cells does provide an environment in which increased amounts of endogenous intracellular peptides may be transported to the cell surface, thereby becoming potential targets of immune-surveillance and cell-mediated cytotoxicity. Conversely, HSP may play a protective role in such a manner that selected groups of pancreatic ductular epithelial cells withstand cytotoxic damage of chemical, metabolic, or immune origin, and for significantly increased periods of time than they would otherwise; HSP thereby conserve a population of "reserve" epithelial cells from which pancreatic regeneration might occur. Identification of distinct pathogenic groups, defined according to precise immunohistochemical criteria, might provide the basis of a functional assessment and hence allow development of biologically appropriate strategies for managing individual patients with chronic pancreatitis.

Do patients with the sleep apnea/hypopnea syndrome drink more alcohol?

As alcohol ingestion may worsen the sleep apnea/hypopnea syndrome, we have investigated the alcohol consumption of patients with the sleep apnea/hypopnea syndrome in comparison to control subjects to determine whether patients with the sleep apnea/hypopnea syndrome drink excessively. A lifetime alcohol history was taken from each. There was no significant difference between the 50 patients with the sleep apnea/hypopnea syndrome and 95 age-matched controls in either the lifetime (patients 27, SEM 5 x 10(3); controls 26, SEM 4 x 10(3) units) or current (12, SEM 2; 12, SEM 2 units per week) alcohol consumption. There was no evidence that alcohol consumption was related to the development of arterial carbon dioxide retention or peripheral edema in such individuals.

The effect of posture on upper airway dimensions in normal subjects and in patients with the sleep apnea/hypopnea syndrome

The effect of posture on upper airway dimensions was assessed for two reasons. First, some patients with untreated sleep apnea/hypopnea syndrome (SAHS) report they sleep better sitting upright. Second, to allow comparison of the differing techniques used to determine the site of maximal airway narrowing in awake patients with SAHS, as some are carried out in the erect and others in the supine posture. Lateral cephalometry was therefore carried out in 33 nonsnoring normal subjects and in 29 patients with obstructive SAHS (mean apneas plus hypopneas, 46 per hour; range, 17 to 103). In both normal subjects and patients, uvular width was increased (p less than 0.05) in the supine posture, and this was associated with significant narrowing of the retropalatal airway in the patients with SAHS (erect, 5.0 +/- SD 2.6 mm; supine, 3.6 +/- 2.8 mm; p less than 0.01). In both normal subjects and patients, the retroglossal hypopharynx widened (p less than 0.05) in the supine posture (e.g., in patients with SAHS, posterior airway space was: erect, 11.5 +/- 4.5 mm; supine, 13.4 +/- 4.8 mm; p = 0.003). In the supine posture there was anterior movement of the hyoid and neck flexion in both groups. However, a study of the effect of neck flexion in the erect posture showed that neck flexion produced no changes in airway caliber. Thus, posture is an important determinant of upper airway dimensions.