The influence of alcohol consumed with a meal on endothelial function in healthy individuals.

BACKGROUND: Alcohol and polyphenols in wine and fruit juices have been strongly implicated in the favourable effects on of these beverages on vascular function. Despite a wealth of information on the metabolic and vascular effects of alcohol and polyphenols, the combined influences of these substances on vascular function, especially when consumed with food, is poorly understood. A study was designed to determine the effects of a phenolic-rich grape juice, with or without alcohol, on vascular endothelial function in the postprandial state. METHODS: Ten subjects consumed a standard meal with a test drink on three separate occasions. On each occasion, the test drink accompanying the meal was either red grape juice, red grape juice plus alcohol (12% v/v), or water. Endothelial function was measured by flow mediated dilatation (FMD) prior to then 30 and 60 minutes after consuming the meal. Blood samples were taken for the determination of plasma glucose, triacylglycerol (TAG) and non esterified fatty acids (NEFA) at regular intervals. RESULTS: There was a significant effect of the three treatments (P = 0.0026) and time (P = 0.021) on percentage FMD. The meals with the grape juice and grape juice plus alcohol produced similar FMD responses but were both significantly greater than the meal with water. The concentration of plasma glucose, TAG and NEFA were similar after each treatment. CONCLUSION: Alcohol had no effect on vascular function in the early postprandial phase. These findings provide new evidence to support the potential benefit of non-alcoholic components within alcoholic beverages on vascular function in the fed state.

Evaluating the role of magnetic resonance imaging scans in the surgical management of acoustic neuromas.

OBJECTIVE: To assess the reliability of magnetic resonance imaging (MRI) in predicting the size and position of an acoustic neuroma, with particular reference to the intracanalicular portion. STUDY DESIGN: Prospective study comparing the position of the tumor in the internal auditory canal on fast spin-echo MRI with the actual position measured intraoperatively. METHODS: The study was performed in a tertiary referral neurotology center, encompassing both the public and private health care systems. Fifteen consecutive patients admitted for acoustic neuroma removal via the translabyrinthine approach were studied. The main outcome measure was tumor position in the internal auditory canal expressed in millimeters, accurate to the nearest 0.5 mm. RESULTS: The fast spin-echo MRI was accurate within an error of 1 mm in predicting the lateral extent of the tumor in the internal auditory canal. CONCLUSION: Fast spin-echo MRI can accurately predict the lateral extent of an acoustic neuroma and allow accurate planning of the surgical approach.

The influence of the colon on postprandial glucagon-like peptide 1 (7-36) amide concentration in man.

Glucagon-like peptide (7-36) amide (GLP-1) is an incretin hormone of the enteroinsular axis released rapidly after meals despite the fact that GLP-1 secreting cells (L-cells) occur predominantly in the distal gut. The importance of these colonic L-cells for postprandial GLP-1 was determined in healthy control subjects and in ileostomy patients with minimal small bowel resection (<5 cm). Subjects were fed a high complex carbohydrate test meal (15.3 g starch) followed by two carbohydrate-free, high fat test meals (25 g and 48.7 g fat respectively). Circulating levels of glucose, insulin, glucagon, glucose insulinotrophic peptide (GIP) and GLP-1 were measured over a 9-h postprandial period. For both subject groups the complex carbohydrate test meal failed to elicit a rise in either GIP or GLP-1. However, both hormones were elevated after the fat load although the GLP-1 concentration was significantly reduced in the ileostomist group when compared with controls (P=0.02). Associated with this reduction in circulating GLP-1 was an elevation in glucagon concentration (P=0.012) and a secondary rise in the plasma glucose concentration (P=0.006). These results suggest that the loss of colonic endocrine tissue is an important determinant in the postprandial GLP-1 concentration. Ileostomists should not be assumed to have normal enteroinsular function as the colon appears to have an important role in postprandial metabolism.

Altered postprandial hormone and metabolic responses in a simulated shift work environment.

The circadian rhythms of most night shift workers do not adapt fully to the imposed behavioural schedule, and this factor is considered to be responsible for many of the reported health problems. One way in which such disturbances might be mediated is through inappropriate hormonal and metabolic responses to meals, on the night shift. Twelve healthy subjects (four males and eight females) were studied on three occasions at the same clock time (1330 h), but at different body clock times, after consuming test meals, first in their normal environment, secondly after a forced 9 h phase advance (body clock time approximately 2230 h) and then again 2 days later in the normal environment. They were given a low-fat pre-meal at 0800 h, then a test meal at 1330 h with blood sampling for the following 9 h. Parameters measured included plasma glucose, non-esterified fatty acids (NEFAs), triacylglycerol (TAG), insulin, C-peptide, proinsulin and glucose-dependent insulinotropic polypeptide, and urinary 6-sulphatoxymelatonin. In contrast with a previous study with a high-fat pre-meal, postprandial glucose and insulin responses were not affected by the phase shift. However, basal plasma NEFAs were lower immediately after the phase shift (P < 0.05). Incremental (difference from basal) TAG responses were significantly higher (P < 0.05) immediately after the phase shift compared with before. Two-day post-phase shift responses showed partial reversion to baseline values. This study suggests that it takes at least 2 days to adapt to eating meals on a simulated night shift, and that the nutritional content of the pre-meals consumed can have a marked effect on postprandial responses during a simulated phase shift. Such findings may provide a partial explanation for the increased occurrence of cardiovascular disease reported in shift workers.

Cochlear implant extrusion in a child with keratitis, ichthyosis and deafness syndrome.

We present a child with keratitis, ichthyosis and deafness (KID) syndrome implanted with a Nucleus device. We discuss the would complications of this child and the steps taken to deal with the problems encountered when the wound failed to heal, followed by the partial extrusion of her implant. Early surgical management involved resuturing the wound but when this failed a rotational flap was required to cover the implant package and allow eventual healing. Despite the wound problems and revision surgery she has a good audiological result.

Subcutaneous emphysema as a complication of tonsillectomy.

Subcutaneous emphysema occurs when air is introduced into the tissues. This can happen as a complication during, or immediately after surgery. It has rarely been described after tonsillectomy. Definitive treatment will depend on the cause. We report two cases of subcutaneous emphysema following tonsillectomy.

Perforation rates after ventilation tube insertion: does the positioning of the tube matter?

A prospective study was performed of children undergoing bilateral ventilation tube insertion. One hundred and twenty-one children aged between 9 months and 10 years 3 months were admitted for surgery for secretory otitis media (glue ear). Each child had a ventilation tube inserted anteriorly in the tympanic membrane of one ear and posteriorly in the tympanic membrane of the other. They underwent regular clinical and audiological assessment until extrusion of the ventilation tubes occurred. Perforations were noted in 2.75% of tympanic membranes (4.6% of the children). The rate with posteriorly placed ventilation tubes was higher than with the anteriorly placed ventilation tubes (3.7% compared with 1.8%) though this is not statistically significant.

Postprandial hormone and metabolic responses in simulated shift work.

This study was designed to investigate postprandial responses to a mixed meal in simulated shift work conditions. Nine normal healthy subjects (six males and three females) were studied on two occasions at the same clock time (1330 h) after consuming test meals, first in their normal environment and secondly after a 9 h phase advance (body clock time 2230 h). Plasma glucose, insulin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), triacylglycerol (TAG) and non-esterified fatty acids (NEFAs) were determined at intervals for 6 h after each test meal. Postprandial plasma glucose, insulin, GIP and GLP-1 profiles were evaluated by calculating areas under the curve (AUC) for the first 2 h and the last 4 h of the sampling together with total AUC. Significantly higher postprandial glucose responses (total AUC) were observed after the phase shift than before (AUC 0-360 min, 2.01 (1.51-2.19) vs 1.79 (1.56-2.04) mmol/l.min; P < 0.02; mean (range)). No significant difference was observed when the first 2 h of each response was compared, but significantly higher glucose levels were observed in the last 4 h of the study after the phase shift than before (AUC 120-360 min, 1.32 (1.08-1.42) vs 1.16 (1.00-1.28) mmol/l.min; P < 0.05). Similar results were obtained for insulin (AUC 0-360 min, 81.72 (30.75-124.97) vs 58.98 (28.03-92.57) pmol/l.min; P < 0.01; AUC 120-360 min, 40.73 (16.20-65.25) vs 25.71 (14.25-37.33) pmol/l.min; P < 0.02). No differences were observed in postprandial plasma GIP and GLP-1 responses before and after the phase shift. Postprandial circulating lipid levels were affected by phase shifting. Peak plasma TAG levels occurred 5 h postprandially before the phase shift. Postprandial rises in plasma TAG were significantly delayed after the phase shift and TAG levels continued to rise throughout the study. Plasma postprandial NEFA levels fell during the first 3 h both before and after the phase shift. Their rate of return to basal levels was significantly delayed after the phase shift compared with before. This study demonstrates that a simulated phase shift can significantly alter pancreatic B-cell responses and postprandial glucose and lipid metabolism.

Stimulatory effects of glucagon-like peptides on human insulinoma cells and insulin-releasing clonal RINm5F cells.

Insulin-releasing effects of glucagon-like peptides, glucagon and various nutrients were examined using tumour cells from a freshly resected human insulinoma and RINm5F cells. Insulin release by human insulinoma cells or RINm5F cells was not affected by 16.7 mM glucose. Both cell types exhibited secretory responses to 20 mM alanine, 25 mM K+ and 7.6 mM Ca2+. Insulin release by human insulinoma cells was enhanced at 2 x 10(-7) M by glucagon, GLP-1[1-37], GLP-1[7-36] and its N- and C-terminal fragments GLP-1[7-14] and GLP-1[31-37]. The intact peptides (2 x 10(-6)-2 x 10(-12) M) also stimulated insulin release by RINm5F cells, but neither of the fragments enhanced secretion. The cyclic AMP content of human insulinoma cells and RINm5F cells was increased by glucagon. GLP-1[7-36] (2 x 10(-8)-2 x 10(-10) M) increased cyclic AMP in RINm5F cells, but no additional effects were noted in these or human insulinoma cells. These results suggest that GLP-1[7-36] stimulates insulin release by a direct action on human and rat B-cells, partly involving modulation of intracellular cyclic AMP.

The extraction and purification of a peptide from rat insulinoma tissue.

A peptide was extracted and purified from rat insulinoma tissue which, although similar, was not identical to normal rat C peptides. The purity of the peptide, called rat insulinoma peptide (RIP), was investigated using polyacrylamide gel electrophoresis, isoelectric focusing and high-performance liquid chromatography. It appears to contain two peptides similar to each other but differing in their isoelectric points. The peptides as assessed by fast atom bombardment mass spectrometry have molecular masses in the region of 1982 Da, given a chain length of approx. 22 amino-acid residues. Evidence obtained using an established rat C peptides radioimmunoassay suggests that RIP shares a common C-terminus with rat C peptides. The antiserum produced to RIP was used to develop a radioimmunoassay using a tracer prepared by iodinating purified tyrosylated RIP.

An immunisation protocol which enhances the frequency of antigen-specific monoclonal antibody production.

An immunisation protocol has been developed for small molecular weight antigens which results in a high percentage of specific hybridomas being produced after cell fusion. An enzyme-linked immunosorbent assay (ELISA) was developed for screening the desired antibodies in the culture supernatants. A conventional immunisation regimen was followed by doses of antigen in sterile water on each of the last 4 days before fusion. A range of antigen doses was used and the specific efficiency of fusion was increased by selection of the optimum amount. The antigen used as a model antigen in these experiments was biosynthetic human insulin.

A direct assay for proinsulin in plasma and its applications in hypoglycaemia.

A direct radioimmunoassay in unextracted plasma is described. The assay has a sensitivity of 4 pmol/l (2 standard deviation from zero). The proinsulin antiserum was immuno-adsorbed against human C-peptide and insulin coupled to glass beads. Cross-reactivity of the antiserum was assessed and shown to be less than 0.01% with both peptides. In normal healthy fasting subjects the plasma proinsulin level was 6.7 +/- 1.7 pmol/l (n = 17) (mean +/- SD). Fasting proinsulin levels in non-insulin dependent diabetics were significantly elevated compared with non diabetics (14.2 +/- 2 pmol/l (n = 11) vs 6.7 +/- 1.7 (n = 17) P less than 0.005). The insulin/proinsulin ratio was 3.4:1 in the non-insulin dependent diabetic compared with 6:1 in non-diabetics. Samples from 21 insulinoma patients were assayed and mean fasting plasma proinsulin level was 255 pmol/l +/- 479 when the patients were hypoglycaemic. The range in pro-insulin levels was large (30-2300 pmol/l). Mean fasting proinsulin level in three hypoglycaemic subjects due to sulphonylurea overdose was 15.7 +/- 2.3 pmol/l. The molar ratio of proinsulin to insulin was 1:6 in healthy subjects, 1:1 in insulinoma patients and 10:1 in sulphonylurea induced hypoglycaemic patients.

The effect of dietary modification and hyperglycaemia on gastric emptying and gastric inhibitory polypeptide (GIP) secretion.

1. Five healthy volunteers whose usual fat and energy intakes were moderately high (fat intake 155 (SE 11) g/d; energy intake 13683 (SE 909) kJ/d) were given on two separate occasions (a) 96 g fat and (b) 96 g fat and intravenous (IV) glucose (250 g glucose/l; 100 ml followed by a 2 ml/min infusion for 180 min). 2. Subjects continued on a low-fat diet for 35 d (fat intake 25 (SE 4) g/d; energy intake 6976 (SE 539) kJ/d) and the tests repeated. 3. The gastric inhibitory polypeptide (GIP) response to oral fat was significantly attenuated by IV glucose whilst subjects were consuming their normal diets and the GIP response to fat alone was significantly diminished during the low-fat diet. Post-prandial plasma triglycerides, light scattering indices (LSI; an index of post-prandial chylomicronaemia) and paracetamol levels paralleled the integrated GIP responses on both normal and low-fat diets. 4. The study of oral fat with or without glucose was repeated on seven further volunteers consuming their usual diet, substituting 10 MBq 99Tcm-labelled tin colloid for the paracetamol to investigate the rate of gastric emptying by radionuclide imaging. 5. Plasma GIP, insulin, triglyceride and LSI levels were similar to those found in the first study. IV glucose almost doubled the gastric emptying time of the oral fat load (half emptying time (t1/2) 148 (SE 11) min after fat alone and 224 (SE 18) min after fat and IV glucose). Post-prandial plasma motilin levels were significantly depressed by IV glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Modifications of gastric inhibitory polypeptide (GIP) secretion in man by a high-fat diet.

1. Five healthy volunteers (usual fat intake 103 (SE 9) g/d and energy intake 9855 (SE 937) kJ/d were given on two separate occasions (a) 100 g oral glucose and (b) sufficient intravenous (IV) glucose to obtain similar arterialized plasma glucose levels to those after oral glucose. 2. Subjects increased their fat intake by 68 (SE 9.6)% for 28 d by supplementing their diet with 146 ml double cream/d (fat intake on high-fat diet (HFD) 170 (SE 8) g/d; energy intake 12347 (SE 770)). 3. The 100 g oral glucose load was repeated and IV glucose again given in quantities sufficient to obtain similar arterialized blood glucose levels. Immunoreactive plasma insulin, C-peptide and gastric inhibitory polypeptide (GIP) were measured. 4. Plasma GIP levels were higher following oral glucose after the HFD (area under plasma GIP curve 0-180 min 1660 (SE 592) v. 2642 (SE 750) ng/l.h for control and HFD respectively; P less than 0.05). Both insulin and C-peptide levels were significantly higher after oral than after IV glucose (P less than 0.01) but neither were affected by the HFD. Glucose levels were lower following the HFD after both oral and IV glucose (area under plasma glucose curve 0-180 min, following oral glucose 6.7 (SE 0.3) mmol/l.h for control and 4.2 (SE 0.6) mmol/l.h for HFD; P less than 0.01). 5. Glucose-stimulated GIP secretion was thus enhanced by the HFD. Insulin secretion in response to oral glucose was unchanged, in spite of an improvement in glucose tolerance. 6. The improvement in glucose tolerance post-HFD could possibly be due to a GIP-mediated inhibition of hepatic glycogenolysis, or a decreased rate of glucose uptake from the small intestine.

Insulin and C-peptide levels after oral and intravenous glucose. Contribution of enteroinsular axis to insulin secretion.

Peripheral venous plasma insulin and C-peptide concentrations were measured in 10 healthy volunteers, given either 100 g glucose orally or sufficient intravenous (i.v.) glucose to produce similar glucose concentrations when measured in arterialized blood. The incremental areas under both the insulin and C-peptide curves were significantly increased after oral as compared with i.v. glucose administration by 229% and 138%, respectively. Arteriovenous plasma glucose differences were higher after oral glucose administration and were positively correlated with plasma insulin concentrations. Plasma gastric inhibitory polypeptide (GIP) and insulin concentrations were measured in seven healthy volunteers given oral glucose loads ranging from 25 to 200 g. Both the magnitude and duration of the GIP and insulin responses after oral glucose ingestion were dose dependent. These results suggest that the main cause of the increase in peripheral insulin levels after large oral carbohydrate loads is augmented insulin secretion rather than reduced hepatic extraction, indicating the possibility that an enteroinsular factor does exist, in accordance with the "incretin" concept. They also emphasize the need to document both arterial and venous glucose concentrations for the correct interpretation of experiments investigating glucose homeostasis.

Specific binding of the C-peptide of proinsulin to cultured B-cells from a transplantable rat islet cell tumor.

Specific binding of the C-peptide of proinsulin was evaluated using a transplantable NEDH rat islet cell tumour predominantly composed of insulin-secreting B-cells. Cultured tumour B-cells exhibited greater than 90% viability assessed by trypan blue exclusion, and retained the ability to form tumours with accompanying hypoglycaemia and hyperinsulinaemia after reimplantation. During binding experiments with synthetic rat C-peptide I and iodinated tyrosylated rat C-peptide I, tumour B-cells exhibited 54 +/- 6% specific binding. Displacement of tracer increased with increasing concentrations of unlabelled rat C-peptide I (0.25-1,000 ng/ml), and the specificity of binding was substantiated by reduced displacement with human C-peptide. Scatchard analysis of specific C-peptide binding revealed a curvilinear plot with upward concavity. The demonstration of specific C-peptide binding to insulin-secreting B-cells provides evidence for a physiological role of proinsulin C-peptide.

Effect of pretreatment with a high fat diet on the gastric inhibitory polypeptide and insulin responses to oral triolein and glucose in rats.

Male Wistar rats were pretreated with 3 ml triolein orally for 4 days in addition to their normal diet. A similar control group were allowed free access to normal laboratory food. When given an oral fat load (1 ml triolein) plasma gastric inhibitory polypeptide (GIP) and triglyceride levels were significantly higher in the fat pretreated group. Inhibition of fat-stimulated GIP release by exogenous insulin was demonstrated in the untreated control group (plasma GIP: 663 +/- 49 versus 853 +/- 92 ng/l, mean +/- SEM p less than 0.025), but pretreatment with an oral fat load abolished this effect (plasma GIP: 1008 +/- 95 versus 1116 +/- 100 ng/l, p NS). Plasma glucose levels were significantly higher in fat pretreated rats given oral fat and intraperitoneal insulin compared with untreated controls (plasma glucose nadir 2.6 +/- 0.48 versus 1.6 +/- 0.15 mmol/l, p less than 0.05). Fat-pretreated rats showed significantly higher insulin and glucose levels compared with the untreated rats when given oral glucose (plasma insulin: 6.2 +/- 1.2 versus 2.5 +/- 0.59 micrograms/l, p less than 0.01; plasma glucose: 10.2 +/- 0.39 versus 8.9 +/- 0.41 mmol/l, p less than 0.025). Pretreatment of rats on a high fat diet causes (1) increased GIP secretion in response to an oral fat load, (2) abolition of the feed-back inhibition of exogenous insulin on fat-stimulated GIP release, and (3) some degree of insulin resistance.

Endocrine pancreatic control of the release of gastric inhibitory polypeptide. A possible physiological role for C-peptide.

Intravenous infusion in anaesthetized rats of rat II C-peptide at a dose which produced circulating levels of 22.8 +/- 1.8 nmol/l after 30 min, resulted in a significant reduction (141 +/- 7 to 50 +/- 4 pmol/l, p < 0.001, mean +/- SEM) in the immunoreactive gastric inhibitory polypeptide response to an intestinal perfusion with a fat emulsion. Immunoreactive insulin levels were unchanged from basal in this study. It is suggested that C-peptide must be considered as a candidate for the endocrine pancreatic factor which exerts a negative feedback upon gastric inhibitory polypeptide release.