Influence of Participant Perceptions of Adherence-Related Interactions with Study/Study Team on Drug Levels: HPTN069 Analysis of Self-Reported Adherence Experiences While on Study

Adherence to HIV pre-exposure prophylaxis (PrEP) study drug is critical for safety, tolerability, and efficacy trials, and may be affected by how adherence is communicated by the study staff to trial participants. Increasingly, clinical trials investigating PrEP are creating and implementing 'participant-centered' approaches that discuss potential non-adherence neutrally (without negative judgement) and support efforts to adhere versus insisting on perfect adherence. In the HPTN069/ACTG A5305 study, we evaluated participant experiences of potentially negative adherence-related interactions with study teams using ten items to characterize the frequency of such experiences. We related these individual items and a combined set of seven negative experience items (total negative experience score) to drug concentrations (detectable or consistent with daily-dosing). The exploratory analyses used logistic regression for each experience item on the full sample and disaggregated by sex. Several experiences were related to drug detection and to daily-dosing, although more so for participants identifying as men than women. Total negative experience scores associated with not having detection drug concentrations for the full sample, and remained significant even when controlling for sex, age, and race. Daily dosing was associated with total negative experience score for men in the sample. Additional investigations into adherence-related interactions with study teams that are most problematic or helpful in general and uniquely for men and women are warranted.

Gender-assortative waist circumference in mother-daughter and father-son pairs, and its implications. An 11-year longitudinal study in children (EarlyBird 59)

BACKGROUND/OBJECTIVES

Body mass index (BMI) is reportedly gender assortative (mother-daughter, father-son) in contemporary children. We investigated the corresponding transmission of waist circumference (WC) and its implications.

METHODS

We measured parental WC at baseline and WC, height, weight and para-umbilical skin-fold (USF) annually in their offspring from 5 to 15 years (n = 223 trios). Parents were deemed normal metabolic risk (NR) or high risk (HR) according to World Health Organization (WHO) cut-points for WC (mothers 80 cm, fathers 94 cm). The residual from WC adjusted for BMI (WC|BMI ) was used as a surrogate for excess intra-abdominal fat, and its association with insulin resistance (HOMA2-IR) was sought.

RESULTS

WC and USF were both gender assortative, while WC|BMI was not. WC was greater by 1.62 cm (P < 0.05, confidence interval [CI]: 0.09-3.16) and USF by 0.37 cm (P < 0.01, CI: 0.19-0.56) among the daughters (but not the sons) of HR compared with those of NR mothers, and by 1.32 cm (P < 0.05, CI: 0.09-2.55) and 0.18 cm (P < 0.05, CI: 0.04-0.32), respectively in the corresponding father-son (but not father-daughter) pairings. No such differences could be demonstrated for WC|BMI . A standard deviation score 1(SDS) change in WC|BMI , independent of BMI, was associated with a 7.14% change in IR in girls (P < 0.01, CI: 1.76-12.80) and 8.02% in boys (P < 0.001, CI: 2.93-13.36), but there was no relationship between IR and USF.

CONCLUSION

The relationship of offspring WC to metabolic health and to parental size is complex. Subcutaneous abdominal fat is gender assortative but harmless, while intra-abdominal fat (its surrogate in this analysis) is unrelated to parental waist circumference, but metabolically harmful.

Association of immune mediators at diagnosis of Type 1 diabetes with later clinical remission

AIMS

We tested the hypothesis that systemic concentrations of cytokines, chemokines or soluble cytokine receptors predict or accompany clinical remission in Type 1 diabetes (T1D).

METHODS

In a prospective, multicentre study, 48 patients with newly diagnosed T1D and 55 age-matched healthy control subjects were investigated. Blood was drawn 3-7 days after the diagnosis and then 3-4 months later. Patients were grouped into partial remitters or non-remitters by the degree of clinical improvement defined by HbA(1c) (threshold 7.5%) and daily insulin dose (threshold 0.38 IU/kg/day). Systemic concentrations of 17 immune mediators were analysed in serum or plasma. In addition, autoantibodies against insulin (IAA), IA-2 (IA-2A) and GAD65 (GADA) were quantified.

RESULTS

All 17 immune mediators showed remarkable intra-individual stability in their systemic concentrations over time. As a consequence, partial remission was not accompanied by changes in mediator levels except for a moderate decrease of interleukin (IL)-1ra concentrations (P = 0.02) and IL-10 concentrations (P = 0.01) in non-remitters. Baseline levels were associated with the later clinical course in that low levels of interferon gamma (P = 0.01), IL-10 (P = 0.03) and IL-1R1 (P = 0.009) concentrations were observed in partial remitters.

CONCLUSIONS

We conclude that the systemic immunoregulatory state at diagnosis of T1D is predictive of clinical improvement during the remission phase. There was no general change in systemic immune reactivity in the months after diagnosis and initiation of insulin therapy.

Association of interferon-gamma and interleukin 10 genotypes and serum levels with partial clinical remission in type 1 diabetes

We studied whether serum interferon (IFN)-gamma or interleukin (IL)-10 levels and their corresponding functional polymorphic genotypes are associated with partial remission of type 1 diabetes (T1D). A multi-centre study was undertaken in patients with newly diagnosed T1D and matched controls. T1D patients were followed for 3 months and characterized for remission status. Partial clinical remission was defined as a daily insulin dose <or= 0.38 units/kg/24 h with an HbA1c <or= 7.5%. Thirty-three patients and 32 controls were phenotyped for serum concentrations of IFN-gamma and IL-10 and genotyped for functional polymorphisms of the IFN-gamma and IL-10 genes. Sixteen of 25 informative patients (63%) remitted. Serum IFN-gamma concentrations were significantly decreased in remitters but increased in non-remitters compared to controls, and did not change over time in any group. IFN-gamma genotypes corresponded with serum levels in controls and non-remitters, but not in remitters who displayed the lowest serum IFN-gamma levels despite more often carrying high-producing IFN-gamma genotypes. Neither the frequency of IL-10 genotypes nor serum IL-10 concentration differed between patients and controls. The combination of high-producing IFN-gamma genotype together with low serum IFN-gamma concentration at the time of diagnosis provided a strong positive predictive value for remission. Serum IFN-gamma concentrations predicted by genotype and observed serum levels were discordant in remitters, suggestive of regulation overruling genetic predisposition. Although high-producing genotypes were less frequent in remitters, they were predictive of remission in combination with low serum IFN-gamma levels. These data imply that remission is partially immune-mediated and involves regulation of IFN-gamma transcription.

The effect of metformin on fat distribution and the metabolic syndrome in women with polycystic ovary syndrome--a randomised, double-blind, placebo-controlled trial

OBJECTIVE

To establish whether metformin has a significant action in reducing visceral fat and improving other metabolic parameters in women with polycystic ovary syndrome (PCOS).

DESIGN

Randomised, double-blind, placebo-controlled trial.

SETTING

Reproductive medicine clinic.

POPULATION

Forty women with anovulatory PCOS.

METHODS

Participants were randomised into receiving metformin 500 mg three times a day or placebo for 3 months.

MAIN OUTCOME MEASURES

Fat distribution was measured by computed tomography scan. Secondary outcome measures included serum indices of the metabolic syndrome and evidence of ovulation.

RESULTS

We found no significant differences in any of the measures of fat distribution between the placebo and metformin groups. The metformin group had significantly lower total cholesterol (P= 0.02), low-density lipoprotein cholesterol (P= 0.02) and cholesterol:high-density lipoprotein cholesterol ratio (P= 0.05), but there was no statistically significant treatment effect on androgens, insulin, insulin resistance, triglycerides, ovulation or pregnancy.

CONCLUSIONS

Metformin has no clinically significant effect in reducing visceral fat mass, although it does have a beneficial effect on lipids. This trial lends support to the growing evidence that metformin is not a weight loss drug. Metformin might therefore be used as an adjunct to lifestyle modification in women with PCOS, but not as a substitute for it.

The central issue? Visceral fat mass is a good marker of insulin resistance and metabolic disturbance in women with polycystic ovary syndrome

OBJECTIVE

To establish whether visceral fat mass is the most significant variable correlating with insulin resistance and other metabolic parameters in women with polycystic ovary syndrome (PCOS).

DESIGN

Prospective cross-sectional trial.

SETTING

Reproductive medicine clinic.

POPULATION

Forty women with anovulatory PCOS.

METHODS

Measurements were taken at recruitment, and analysis was performed to define correlations between the outcome measures and the explanatory variables.

MAIN OUTCOME MEASURES

Visceral and subcutaneous fat by computed tomography scan, insulin resistance, anthropometric measures, markers of the metabolic syndrome and androgens.

RESULTS

Strong linear correlation of visceral fat to insulin resistance (r = 0.68, P < 0.001) was observed. There were also statistically significant correlations with fasting insulin (r = 0.73, P < 0.001), homeostasis model assessment beta-cell function (r = 0.50, P = 0.007), triglycerides (r = 0.45, P = 0.003), high-density lipoprotein cholesterol (r = -0.42, P = 0.007), urate (r = 0.47, P = 0.002), Sex hormone binding globulin (r = -0.39, P = 0.01) and luteinising hormone (r = -0.32, P = 0.02). There were no significant correlations of testosterone with fat distribution or metabolic parameters. Insulin resistance showed closest correlation to visceral fat mass (r = 0.68, P < 0.001), then to waist circumference (r = 0.62, P < 0.001), with the weakest correlation being waist:hip ratio (r = 0.36, P = 0.01). The best regression model for predicting insulin resistance is with visceral fat mass and triglycerides as the explanatory variables (r = 0.72, P < 0.001).

CONCLUSIONS

Visceral fat is the most significant variable correlating with metabolic dysfunction in women with PCOS. Our data support the hypothesis that visceral fat either causes insulin resistance or is a very early effect of it. It also implies that reducing visceral fat should reduce insulin resistance which may account for the observations that exercise and weight loss appear to be more effective interventions than pharmacological treatments. The best anthropometric measure of insulin resistance is waist circumference.

Increasing body weight predicts the earlier onset of insulin-dependant diabetes in childhood: testing the 'accelerator hypothesis' (2)

AIMS AND METHODS

It has recently been hypothesized that weight gain in childhood accelerates the onset of Type 1 diabetes, as well as increasing its risk, and that Type 1 diabetes and Type 2 diabetes may be one and the same disorder of insulin resistance. An explanation is needed for the rising incidence of childhood diabetes and, to test the Accelerator Hypothesis, we examined the anthropometric measurements recorded from birth in 168 young people presenting with Type 1 diabetes between 1980 and 2002. Pre-onset as well as peri- and post-onset measurements of height and weight were available, and waist circumference was recorded at various intervals after onset.

RESULTS

The mean birth weight of the children and their height, weight and body mass index (BMI) at diagnosis lay close to the population mean. However, pre-onset and post-onset BMI were both well above the population mean, were closely correlated with each other (r = 0.79, P < 0.001) and (inversely) with age at onset (r = -0.30, P < 0.001). A significant correlation was also found between BMI standard deviation scores (sds) and year of diagnosis (r = 0.27, P < 0.001) and, importantly, waist circumference sds in the children with Type 1 diabetes was found to be substantially greater than average for the population [boys: +0.96 (sd 1.04), girls: +1.30 (sd 0.89)].

CONCLUSIONS

The data suggest that children with Type 1 diabetes have become progressively heavier at diagnosis over the past 20 years, and that the heavier child develops it earlier. Waist circumference, a proxy for visceral fat mass and insulin resistance, is substantially greater in children with Type 1 diabetes. Weight centile crossing appears to be an important environmental accelerator which may contribute to or account for the striking increase in both Type 1 diabetes and Type 2 diabetes in childhood. A reduction of body weight and improved lifestyle might reverse this trend in both types of diabetes.

Renal Arterial Stenosis in Renal Allografts: Retrospective Study of Predisposing Factors and Outcome after Percutaneous Transluminal Angioplasty

PURPOSE

To determine the predisposing factors to transplant renal arterial stenosis (TRAS) and assess the outcome of percutaneous transluminal angioplasty (PTA) as the primary treatment.

MATERIALS AND METHODS

Of 831 renal allograft recipients (584 cadaveric, 247 living related) between January 1991 and December 1998, 72 had hypertension and/or renal dysfunction. All 72 underwent arteriography, and their medical charts were retrospectively reviewed.

RESULTS

Prevalence of TRAS was 3.1% (26 of 831). Technical success rate of PTA was 94% (16 of 17), and clinical success rate was 82% (14 of 17). Those with renal dysfunction had a mean pre-PTA creatinine value of 2.6 mg/dL (230 micromol/L) +/- 0.5 (SD) versus a 1-week post-PTA value of 1.7 mg/dL (150 micromol/L) +/- 0.3 (P <.001). Of those with hypertension, all but one had substantial improvement in mean diastolic blood pressure. At 26.9 months mean follow-up in 16 patients with successful PTA, two stenoses reoccurred, and two grafts were lost to chronic rejection. TRAS was present in 14 of 45 end-to-side anastomoses and 12 of 27 end-to-end anastomoses (P =.31), and TRAS was more prevalent in cadaveric grafts (24 of 584) than in living related grafts (two of 247). In cadaveric grafts, the mean cold ischemia time was 29.0 hours +/- 6.9 in those with TRAS (n = 24), as compared with 25.5 hours +/- 8.1 in those with no TRAS (n = 39; P = .35). Seven of 17 patients with acute rejection and six of 35 with chronic rejection had TRAS.

CONCLUSION

Primary treatment of TRAS with PTA has good intermediate-term results. TRAS is more prevalent in cadaveric allografts with long cold ischemia time.

Type 2 diabetes in children

The prevalence of type 2 diabetes mellitus is increasing in children and is reaching epidemic proportions in some western countries. Sue Howdle and Terry Wilkin examine the extent of the problem, the disease process, screening, prevention and management of type 2 diabetes.

Missense mutations in the insulin promoter factor-1 gene predispose to type 2 diabetes

The transcription factor insulin promoter factor-1 (IPF-1) plays a central role in both the development of the pancreas and the regulation of insulin gene expression in the mature pancreatic beta cell. A dominant-negative frameshift mutation in the IPF-l gene was identified in a single family and shown to cause pancreatic agenesis when homozygous and maturity-onset diabetes of the young (MODY) when heterozygous. We studied the role of IPF-1 in Caucasian diabetic and nondiabetic subjects from the United Kingdom. Three novel IPF-1 missense mutations (C18R, D76N, and R197H) were identified in patients with type 2 diabetes. Functional analyses of these mutations demonstrated decreased binding activity to the human insulin gene promoter and reduced activation of the insulin gene in response to hyperglycemia in the human beta-cell line Nes2y. These mutations are present in 1% of the population and predisposed the subject to type 2 diabetes with a relative risk of 3.0. They were not highly penetrant MODY mutations, as there were nondiabetic mutation carriers 25-53 years of age. We conclude that mutations in the IPF-1 gene may predispose to type 2 diabetes and are a rare cause of MODY and pancreatic agenesis, with the phenotype depending upon the severity of the mutation.

Delayed disappearance of human compared to porcine insulin in a patient with the insulin autoimmune syndrome

The insulin autoimmune syndrome is characterised by high titres of autoantibody to insulin, a high circulating concentration of total insulin and later, reactive hypoglycaemia. We have studied a patient with this syndrome whose insulin autoantibody bound exclusively human insulin. This permitted us to investigate the disappearance of bound (human) and unbound (porcine) insulin in the same patient, using i.v. injections of 0.075 U/g of each insulin on separate days. The peak plasma free insulin concentration following porcine insulin was four times greater than that following the same dose of human insulin. The plasma disappearance half-time of porcine insulin following injection was 11 min compared with 32 min following human insulin injection, and the area beneath the disappearance curve of free insulin during the 120 min of sampling was greater for porcine insulin by a factor of 3.15. The nadir in plasma glucose occurred at 45 min following porcine insulin and at 90 min following human insulin injection. The restoration of basal glucose concentration was correspondingly slower following human insulin, but the absolute fall in glucose achieved was no different. There was no evidence of insulin resistance. Insulin autoantibodies can seriously disturb the kinetics and effect of free insulin.

An enzyme-linked immunosorbent assay (ELISA) for the measurement of serum antibodies to growth hormone. The Wessex Growth Study

A solid-phase enzyme-linked immunosorbent assay for measuring antibodies to growth hormone (GH) was developed, with occasional use and long shelf-life in mind. With coating protein concentration optimised, the standard curve was linear over a 25-fold range of concentration. The interassay coefficient of variation ranged from 14.4% to 9.3%. The specificity of the assay was confirmed by the substitution of insulin for GH as coating protein and by preabsorption of sera with GH coupled covalently to Sepharose beads. There was no binding signal with insulin and absorption was dose dependent, maximum (greater than 80% complete) with 2 x 10(4) micrograms GH/ml undiluted serum. The assay was simple to perform, cheap and reliable.

The Wessex Growth Study: first report

The Wessex Growth Study is a community-based longitudinal survey of short children recruited from two Health Districts in Wessex during 1985-86 (cohort I) and 1986-87 (cohort II). Screening of new school entrants during 1985-86 identified only 1.3% who were at or below the 3rd centile for height as defined by Tanner and Whitehouse, suggesting a strong secular trend and an urgent need for updated height charts. After exclusion of the small number of children with underlying organic pathology and those from ethnic minorities, there were 84 children in cohort I on whom this report is based. These apparently normal, short children were sex- and age-matched with normal controls (10th-90th centile) from the same school class. Forty-two per cent of cohort I had a delayed bone age, and 34% lay above the 3rd centile after correction for parental height. Forty-four per cent were of low birth weight. The correlation between two successive height velocities measured at 6 and 12 months was only -0.14 for cohort I and -0.15 for their controls. Twelve-month mean height velocity SD scores (SDS) were -0.45 and +0.25, respectively, corresponding to the 33rd and 60th centiles, and rather higher than the 25th and 50th centiles expected in view of the heights of these children. Thirty-eight per cent of cohort I had a 12-month height velocity below the 25th centile, and in 16% height velocity was below the 10th centile. As a group, the children in cohort I grew more slowly than their controls, but the height velocity in 88% of cases lay within the control range.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin autoantibodies and insulin assay

Insulin antibodies are known to interfere with the radioimmunoassay of insulin. We tested intravenous glucose tolerance on 25 insulin autoantibody-positive (IAA+) patients and 25 IAA- controls, who were matched for sex, age, and body mass index, to establish if IAA could also interfere with insulin assay. Insulin content was measured in untreated serum, serum precipitated with polyethylene glycol (PEG, free insulin), and serum extracted with acid and precipitated with PEG (total insulin). The mean untreated first-phase insulin response (I1 + 3) for IAA+ patients was 172 +/- 67.3 mU/L, significantly higher than the mean control value of 108 +/- 47.5 (P less than .001). After PEG precipitation, mean I1 + 3 in the patient group fell significantly to 105 +/- 48.4 mU/L (P less than .001), but the control value was unchanged (104 +/- 45.5). The mean percentage fall after PEG precipitation was 36.9% (patients) and 2.9% (controls) (t = 8.3, P less than .001). There was a strong correlation between the IAA titer and the interference in the insulin assay (r = .81). After total insulin extraction of IAA samples, there was a significant fall in mean I1 + 3 to 134 +/- 55.4 mU/L (P less than .001), but the control value was unchanged. IAA can significantly falsify insulin measurement, and care must be taken in the interpretation of insulin-release tests when IAA is present.

Insulin autoantibody polymorphisms with greater discrimination for diabetes in humans

Insulin autoantibodies, like islet cell antibodies, are found not only in the sera of newly diagnosed Type 1 (insulin-dependent) diabetic patients and their relatives, but also in patients with other autoimmunities who do not develop diabetes. Insulin autoantibodies are oligo/monoclonal and frequently binding-site restricted. As determinant selection is genetically determined, we questioned whether certain polymorphisms of insulin autoantibodies, identified by their binding site on the insulin molecule, could better discriminate for Type 1 diabetes, which is also HLA determined. First, we raised monoclonal antibodies to human insulin by classic fusion methods in order to determine the range of antibody polymorphism, and identified five distinct types by their binding profiles to a panel of insulin variants, using an enzyme-linked immunosorbent assay. Two of these polymorphisms, type A and type B, were subsequently found in insulin autoantibody positive human sera using the same panel of insulin variants, and successfully distinguished diabetes-related from diabetes-unrelated individuals. Thus, the type B polymorphism was responsible for binding in 60% of 41 insulin autoantibody positive individuals with polyautoimmune disease but no personal or family history of diabetes (diabetes unrelated), but in only 2% of a group which comprised 17 newly-diagnosed insulin autoantibody positive Type 1 diabetic patients, 19 insulin autoantibody positive discordant twins of Type 1 diabetes and six insulin autoantibody positive healthy siblings of Type 1 diabetic patients (diabetes related) (p less than 0.01). Isolation of the type A polymorphism alone reduced the proportion of false negatives in the insulin autoantibody test for diabetes relatedness from 49% to 20% without diminishing its specificity.(ABSTRACT TRUNCATED AT 250 WORDS)

On the relationship between islet cell antibodies and insulin autoantibodies in patients at risk from insulin dependent diabetes

The frequencies of islet cell antibodies (ICA) and insulin autoantibodies (IAA) were studied in three clinically well defined groups, using an aprotinin sensitised indirect immunofluorescence assay for ICA and a direct binding solid ELISA for IAA, and the association of these two serological markers for insulin dependent diabetes analysed. Frequency of ICA was 10.7% in siblings of diabetics, 15.5% in discordant identical twins and 65.9% in newly diagnosed diabetic patients. Frequency of IAA was 7.1% in siblings, 46.7% in discordant twins and 38.6% in newly diagnosed diabetic patients. No correlation was demonstrated between the two autoantibodies in the siblings. In the newly diagnosed diabetic patients there were sera positive or negative for both, but 22 (50%) of the sera showed dissociation between the two antibodies. The studies of twins showed that IAA and ICA fluctuated independently with time, and demonstrate the inappropriateness of seeking such an association in cross-sectional surveys. An association could not be demonstrated in this group even if data from multiple samples taken at different points in time were pooled, scoring an individual as positive if at any time their sera had been positive for the corresponding antibody. Thus our data showed no correlation between ICA and IAA in any of the groups studied.

Differences in epitope restriction of autoantibodies to native human insulin (IAA) and antibodies to heterologous insulin (IA)

The binding profiles of insulin autoantibodies (IAA) and insulin antibodies (IA) to highly purified species variants and fragments of insulin were studied in direct immunospecific enzyme-linked immunosorbent assay (ELISA) and indirect absorption experiments with insulins covalently coupled to Sepharose beads. Five of 10 IAA-containing sera from insulin-naive nondiabetics that bound whole human (H) insulin did not bind whole porcine (P) or whole bovine (B) insulins. These sera bound H insulin B-chain but not P B-chain or desalanated P insulin, suggesting they were dependent on the presence of threonine B30. The other 5 IAA-containing sera bound H, P, B, and desalanated porcine insulins, but only 1 bound isolated B-chains. All 10 IA-containing sera from insulin-treated diabetics bound H, P, B, and desalanated P insulins, but only 1 bound to human (and porcine) B-chain. Further binding studies with ovine, rabbit, rat, and guinea pig insulins confirmed the H (threonine B30) specificity of the 5 IAA-containing sera. B30 residues do not appear to be dominant, however, when insulin is administered exogenously. Instead, IA bind predominantly to A-chain or conformational determinants involving both chains. Scatchard analysis of a representative H insulin-specific IAA serum suggested that it contained a single binding affinity, whereas analysis of a representative IA-diabetic serum suggested it contained several different affinities.

Comparison of liquid phase radiobinding assay and solid phase ELISA for the measurement of insulin antibodies and insulin autoantibodies in serum

Sera containing insulin antibodies from 20 insulin-treated diabetic patients, sera containing insulin autoantibodies from 20 insulin-naive non-diabetic patients, and from 10 normal controls, were tested at 1:20 dilution in three different radioimmunoassays (RIA) and an enzyme linked immunosorbent assay (ELISA), using a highly purified human insulin ligand. The RIA using insulin radiolabelled at multiple sites detected insulin antibodies in 17/20 and insulin autoantibodies in 13/20 sera. The same RIA using A-14-monoiodinated insulin was sensitive to antibodies and autoantibodies in all the sera. The same RIA using sera after insulin extraction detected only 13/20 diabetic sera and 9/20 autoimmune sera as positive, owing to a substantial rise in non-specific binding of the control sera. ELISA was sensitive to insulin antibodies and autoantibodies in every case. When binding curves for ELISA and the most sensitive RIA were compared using serial dilutions of four insulin antibody containing sera and four insulin autoantibody containing sera, antibody titres varied from 1.1 to 3.8 times higher in ELISA, and autoantibody titres from 10.6 to 28.6 times higher in ELISA. These studies indicate that ELISA is more sensitive than RIA to insulin antibodies, and in particular to insulin autoantibodies.

Value of insulin autoantibodies as serum markers for insulin-dependent diabetes mellitus

Insulin autoantibodies (IAA) were studied in newly diagnosed insulin-dependent diabetics before the start of insulin treatment and in unaffected identical twins of insulin-dependent diabetics. In 15 of the 40 (38%) diabetics and 27 of the 58 (47%) twins IAA levels exceeded those of 100 controls. Frequency of IAA in unaffected twins was not related to duration of diabetes in their affected twin. In 11 unaffected twins, IAA levels differed in two samples taken 1-12 years apart; IAA were detected at least once in all twins and in one on both occasions. IAA in the twins were not related to the presence of islet-cell antibodies or to HLA-DR 3 or 4. As the unaffected twins of longstanding diabetics are unlikely to develop diabetes, these observations suggest that IAA do not always presage diabetes and are probably not a consequence of the disease; they may reflect an inherited autoimmune tendency to diabetes.

A micro enzyme-linked immunosorbent assay for insulin antibodies in serum

A solid-phase micro enzyme-linked immunosorbent assay for the measurement of insulin antibodies in serum is described and its performance compared with that of an established radiobinding assay. Interassay precision in the ELISA was 10% or less at widely spaced points on the dilution curves for human, porcine and bovine insulins. Specificity was demonstrated by substituting purified human gamma-globulin for the test serum and glucagon for the insulin. The influence on ELISA of endogenous insulin in the test serum was examined by measuring antibody binding before and after extraction of the insulin. The correlation between results from extracted and unextracted sera was 0.96 and the fit ideal: y = 1.00x + 0.38%. The correlation between the results of measuring insulin antibody in 256 diabetic sera by the 2 assays was r = 0.74, P less than 0.001 (human insulin) and r = 0.71, P less than 0.001 (porcine insulin). ELISA is cheap and simple to perform. We believe it may prove to be a practical alternative to radioassay in both the routine detection and investigative research of insulin antibodies.

A microenzyme-linked immunosorbent assay for urinary albumin, and its comparison with radioimmunoassay

Interest in early albuminuria ('microalbuminuria') has intensified recently, particularly in the area of diabetes. We describe a sandwich type enzyme-linked immunoassay for urinary albumin and compare it with a conventional radioimmunoassay (RIA) using the same commercial antiserum. The assay ranges for ELISA and RIA were 7.5-500 micrograms/l and 20-5000 micrograms/l respectively and the corresponding sensitivities were 1.5 ng and 2.0 ng. The correlation coefficient between ELISA and RIA in the measurement of albumin in overnight urine samples from 74 children was r = 0.89 (P less than 0.001). ELISA has several practical advantages over radioimmunoassay, and we believe it has the potential to replace RIA in the screening and study of albuminuria.

Response of urinary albumin to submaximal exercise in newly diagnosed non-insulin dependent diabetes

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