Post-prandial B cell secretions in type II diabetic subjects.
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Aged↗
Biomedical subjects
S M Hampton
Publications and source records attributed to S M Hampton.
The immunological and long-term atopic outcome of infants born to women following a milk-free diet during late pregnancy and lactation: a pilot study.
Infants born to atopic parents have been found to be at high risk of allergy development. The present study investigated the effect of a maternal milk-free diet during late pregnancy and lactation on the immune response and allergy incidence in at-risk and control infants. Atopic mothers were randomly allocated into an intervention group (n 12) or an unrestricted-diet group (n14) and compared with non-atopic mothers following an unrestricted diet (n 12). The intervention involved a maternal milk-free diet during late pregnancy and lactation. Infants were followed up for 18 months postnatally. A significant fall in maternal serum beta-lactoglobulin (beta-Lg)-immunoglobulin G (IgG) antibody levels (P < 0.05) was observed after a 7-week milk-exclusion diet. In maternal and cord serum samples the levels of beta-Lg-IgG and alpha-casein-IgG antibodies were significantly correlated (r 0.89, P < 0.0001 and r 0.71, P < 0.001 respectively). Higher levels of beta-Lg-IgG (P < 0.05) were observed in the cord serum samples compared with paired maternal serum samples. Single-blind allergy assessment by a paediatrician at 12 and 18 months showed that the infants born in the non-atopic group had a significantly lower allergy incidence compared with the infants born in the atopic group following an unrestricted diet (P < 0.008 and P < 0.02 respectively). The allergy incidence in the infants born in the atopic diet group was significantly lower compared with that of the atopic group following an unrestricted diet (P < 0.04). It was observed that the atopic nature of the parents significantly affected the allergy incidence in their children. A trend towards a beneficial effect of a maternal milk-free diet during late pregnancy and lactation was also observed in infants born to atopic parents.
Adult↗
Beta-cell responses in the offspring of non-insulin dependent diabetics after a test meal.
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Adolescent↗
Transfer of cow's milk beta-lactoglobulin to human serum after a milk load: a pilot study.
A sensitive and specific enzyme linked immunosorbent assay (ELISA) was developed for the quantification of cow's milk beta-lactoglobulin in human serum. The assay had a sensitivity of 80 pg/ml (2 standard deviations from zero) and did not cross react significantly with any other tested milk proteins. The absorption of cow's milk beta-lactoglobulin and beta-lactoglobulin immunoglobulin G antibody levels after a milk load was investigated in eight healthy non-allergic individuals. There was a significant variation in the circulating beta-lactoglobulin antigen levels during the six hour period after feeding (p < 0.01) for the combined data. A biphasic absorption pattern was seen in all subjects except one subject who had undetectable levels. No significant variation with time was observed for the beta-lactoglobulin IgG antibody levels and no correlation was found between the beta-lactoglobulin antigen levels and the beta-lactoglobulin IgG antibody levels. This pilot study offered information on the quantity of immunogenic cows' milk protein transferred to the blood after a milk load in non-allergic healthy adults and confirmed a biphasic profile of antigen transfer. The sensitivity of the assay used has shown that transfer of food antigen does occur in the majority of healthy nonallergic subjects.
Adult↗
IgG subclasses to food proteins in atopic and normal individuals.
IgG subclass antibodies to ovalbumin (OVA), gliadin (GLI) and beta-lactoglobulin (beta-lac) were determined in 18 atopic subjects and 18 age- and sex-matched controls. IgG antibodies to OVA and GLI were found predominantly as IgG4 subclass, with the IgG antibodies to beta-lac distributed evenly between IgG2, IgG3 and IgG4 in both groups. The proportion of anti-OVA IgG antibodies in the IgG3 subclass was significantly higher in the atopic group (22%) than in the nonatopic group (8%: p < 0.001). The proportion of anti-GLI IgG3 antibodies was also higher in the atopic group (43%) than the nonatopic group (24%: p < 0.001). OVA subclass antibodies in the atopic and nonatopic subjects were mainly IgG4, and GLI subclass antibodies were mainly IgG3 and IgG4. This study provides information on the distribution of IgG subclasses to food proteins, and in particular those related to protein GLI. The importance of IgG3 subclasses in atopic disease is highlighted; this phenomenon, to our knowledge, has not previously been reported.
Adult↗
Enzyme-linked immunosorbent assays for gliadin and ovalbumin and their application in normal subjects.
Two quick, sensitive and direct sandwich enzyme-linked immunosorbent assays (ELISAs) for the measurement of gliadin and ovalbumin in serum have been developed. The ovalbumin assay has a sensitivity of 0.14 ng/ml (2 SD from zero). Cross-reactivities with ovomucoid and conalbumin were 58% and 0.2%, respectively. No cross-reactivity was observed with bovine serum albumin (BSA), human serum albumin (HSA), gliadin and beta-lactoglobulin. The gliadin assay did not cross-react with BSA, HSA, ovalbumin and beta-lactoglobulin and had a sensitivity of 7 pg/ml. In an acute feeding study, of 6 h duration, serum ovalbumin levels were measured in five non-food-allergic subjects who had been given raw eggs (5 g ovalbumin) after an overnight fast. Following a period of at least 1 week the same subjects were given 132 g wholemeal bread (5 g gliadin) after an overnight fast, and serum gliadin levels were measured. After the consumption of raw eggs ovalbumin levels peaked between 210 and 300 min with maximum serum concentration between 0.52 and 31.08 ng/ml. After the consumption of bread, gliadin levels reached a maximum between 180 and 300 min, reaching peak levels between 1.12 and 12.2 ng/ml. We conclude that levels of detected ovalbumin were higher than those for gliadin in this group of individuals.
Adult↗
Abnormalities in fasting circulating proinsulin concentration in mild gestational diabetes.
Fasting plasma proinsulin, insulin and glucose concentrations were measured in ten women with mild gestational diabetes and ten controls matched for race, age (32 +/- 6 vs 31 +/- 6 years), body mass index (28 +/- 8 vs 27 +/- 6) and gestational week (24 +/- 4 vs 25 +/- 4 weeks). There was no significant difference in fasting plasma glucose between these gestational diabetics and their controls (median 4.7, range 3.7-6.0 mmol/l vs 4.5, range 3.4-5.3 mmol/l). The fasting proinsulin levels were significantly higher in the gestational diabetics compared with the controls (median 12.2, range less than 4-14.8 pmol/l vs 5.8, range less than 4-12.8 pmol/l, P less than or equal to 0.02, Wilcoxon Summed Rank Test), while the calculated intact insulin levels (immunoreactive insulin minus proinsulin) were significantly lower (median 14.5, range 6.3-81.8 pmol/l vs 51.6, range 11.7-312 pmol/l, P less than or equal to 0.01). The ratio of proinsulin to calculated intact insulin was significantly higher in the gestational diabetics than the controls (median 0.66, range 0.16-2.04 vs 0.12, range 0.03-0.62), P less than or equal to 0.01). These results demonstrate that gestational diabetics, with normal fasting plasma glucose values, have abnormalities in pancreatic beta-cell secretion, which are likely to be important both in the aetiology of gestational diabetes and non-insulin dependent diabetes.
Adult↗
Development of an enzyme-linked immunosorbent assay for caffeine.
A competitive enzyme-linked immunosorbent assay suitable for the measurement of caffeine in plasma and serum has been developed. Sheep immunised with an immunogen prepared by coupling 7-(5-carboxypentyl)1,3-dimethylxanthine to egg albumin produced antibodies with little crossreactivity with the metabolites of caffeine. The enzyme label was prepared by coupling 7-(5-carboxypentyl)-1,3-dimethylxanthine to peroxidase using the mixed anhydride method. The assay, which has a sensitivity of 0.01 mumol/l, permits direct measurement of caffeine in plasma and serum samples. 50 plasma samples measured by ELISA and by an established radioimmunoassay showed a correlation of r = 0.97 (P less than 0.001).
Caffeine↗
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.
Adult↗
Circulating and secretory antibodies to specific food proteins in adults.
Indirect enzyme-linked immunosorbent assays (ELISA) for the detection of antibodies to gliadin, beta-lactoglobulin and ovalbumin have been developed. Specific antibody immunoglobulin levels were quantified. Serum and saliva samples were collected from twenty normal subjects and measured for the presence of specific antibodies. For each subject food intake was calculated from a 7-d weighed food inventory record. The total IgG level was 14.2 +/- 4.3 mg/ml (mean +/- s.d.). Levels of beta-lactoglobulin IgG were significantly lower than ovalbumin IgG levels (130 +/- 130 micrograms/ml versus 637 +/- 703 micrograms/ml, P less than 0.01). Gliadin IgG levels were also significantly lower than ovalbumin IgG levels (262 +/- 398 micrograms/ml versus 637 +/- 703 micrograms/ml, P less than 0.05). However, no significant difference was observed between gliadin and ovalbumin IgA levels in the subjects (29 +/- 39 per cent versus 56 +/- 122 per cent). A significant correlation was observed between ovalbumin IgG levels in serum and dietary intake of egg protein (r = 0.46, P less than 0.05). No other significant correlations were observed.
Adult↗
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.
Adenoma, Islet Cell↗
Quantification of total IgG levels against alpha-casein in human serum samples.
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Animals↗
IgG subclasses to specific food proteins in human adults.
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Adult↗
Development of a 3,3',5-tri-iodothyronine enzyme-linked immunosorbent assay.
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Cross Reactions↗
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.
Animals↗
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.
Adult↗
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)
Adult↗
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.
C-Peptide↗