Genomic heterogeneity underlies multidrug resistance in Pseudomonas aeruginosa: A population-level analysis beyond susceptibility testing

BACKGROUND

Pseudomonas aeruginosa is a persistent and difficult-to-treat pathogen in many patients, especially those with Cystic Fibrosis (CF). Herein, we describe a longitudinal analysis of a series of multidrug resistant (MDR) P. aeruginosa isolates recovered in a 17-month period, from a young female CF patient who underwent double lung transplantation. Our goal was to understand the genetic basis of the observed resistance phenotypes, establish the genomic population diversity, and define the nature of sequence evolution over time.

METHODS

Twenty-two sequential P. aeruginosa isolates were obtained within a 17-month period, before and after a double-lung transplant. At the end of the study period, antimicrobial susceptibility testing, whole genome sequencing (WGS), phylogenetic analyses and RNAseq were performed in order to understand the genetic basis of the observed resistance phenotypes, establish the genomic population diversity, and define the nature of sequence changes over time.

RESULTS

The majority of isolates were resistant to almost all tested antibiotics. A phylogenetic reconstruction revealed 3 major clades representing a genotypically and phenotypically heterogeneous population. The pattern of mutation accumulation and variation of gene expression suggested that a group of closely related strains was present in the patient prior to transplantation and continued to change throughout the course of treatment. A trend toward accumulation of mutations over time was observed. Different mutations in the DNA mismatch repair gene mutL consistent with a hypermutator phenotype were observed in two clades. RNAseq performed on 12 representative isolates revealed substantial differences in the expression of genes associated with antibiotic resistance and virulence traits.

CONCLUSIONS

The overwhelming current practice in the clinical laboratories setting relies on obtaining a pure culture and reporting the antibiogram from a few isolated colonies to inform therapy decisions. Our analyses revealed significant underlying genomic heterogeneity and unpredictable evolutionary patterns that were independent of prior antibiotic treatment, highlighting the need for comprehensive sampling and population-level analysis when gathering microbiological data in the context of CF P. aeruginosa chronic infection. Our findings challenge the applicability of antimicrobial stewardship programs based on single-isolate resistance profiles for the selection of antibiotic regimens in chronic infections such as CF.

Quantifying movement of multiple threatened species to inform adaptive management of environmental flows

There is a growing need for water managers to refine and optimise environmental flow strategies (e-flows) to balance water requirements for humans and nature. With increasing demands for freshwater and consequent declines in biodiversity, managers are faced with the problem of how to adaptively manage e-flows for multiple stakeholders and species whose flow requirements may overlap or vary. This study assessed the effectiveness of a regulated e-flow release strategy from a dam, aimed at providing movement opportunities and facilitating reproductive processes for multiple threatened species. Movements of 24 Mary River cod (Maccullochella mariensis), 20 Australian lungfish (Neoceratodus forsteri) and 13 Mary River turtle (Elusor macrurus) were quantified using acoustic telemetry over a three-year period. The influence of regulated e-flow releases, season, river depth, water temperature and rainfall on animal movements was assessed using Generalised linear mixed models (GLMMs). Models showed that hydraulic connectivity provided by both natural flows and regulated e-flow releases facilitated movement of all three species between pool habitats, throughout the year. Mary River turtles made extensive use of regulated e-flow releases when moving between habitats, whereas Mary River cod and Australian lungfish required additional natural rises in river height above the regulated e-flows to trigger movements. Significant movement activity was also recorded for cod and turtles during the dry season (winter and spring), broadly coinciding with breeding periods for these species. The effectiveness of, and potential improvements to, current e-flow strategies to sustain key life-history requirements of these species is discussed. Findings suggest a revised e-flow strategy with relatively minor increases in the magnitude of e-flow releases throughout winter and spring, would be effective in providing movement opportunities and supporting reproductive success for all three species. This study demonstrates that by quantifying movement behaviour in an e-flow context, ecological risk assessment frameworks can then be used to assess and provide for critical life-history requirements of multiple species within the context of a highly regulated system under increasing water use demands.

Diabetic nephropathy in type 1 diabetes: has the outlook improved since the 1980s?

This edition of Then and Now discusses three papers published in Diabetologia in the 1980s relating to diabetic nephropathy. Two epidemiological papers by Andersen et al (1983; 25:496-501) and Borch-Johnsen et al (1985; 28:590-596) described in graphic detail the ravages of diabetic nephropathy in type 1 diabetes. After 40 years of diabetes, 41% of their cohort had developed persistent proteinuria. The median time from first appearance of proteinuria to death was 7-8 years, the majority dying of uraemia or cardiovascular disease. The third paper, by Mathiesen et al (1984; 26:406-410), identified individuals with microalbuminuria, a much earlier stage of diabetic nephropathy, and analysed the risk of progression to persistent proteinuria at various levels of urine albumin excretion. Since the description of microalbuminuria, clinicians have hoped that earlier identification of individuals at high risk of end-stage kidney disease, coupled with aggressive use of reno-protective therapies, would prevent, or at the very least significantly delay, the development of end-stage renal disease. Recent data suggest that the outlook has indeed improved since the 1980s, at least in some populations. However, we may be delaying rather than preventing the development of microalbuminuria, proteinuria and kidney failure. Whilst a delay of 10 or more years in the appearance of end-stage renal disease is very welcome, further work is needed to understand why rates of chronic kidney disease vary substantially between cohorts and to develop novel therapies.

Impact of biomarkers for endothelial dysfunction and procoagulant state on 10-year cardiovascular risk in Type 2 diabetes

AIMS

To estimate the coronary heart disease and cardiovascular disease risk associated with novel biomarkers in Type 2 diabetes mellitus.

METHODS

We measured baseline peripheral blood concentrations of soluble E-selectin, factor XIIa, thrombin-antithrombin III complex and plasminogen activator inhibitor-1 in 86 patients with Type 2 diabetes free of known coronary heart disease. We used Cox proportional hazard models to estimate multivariable-adjusted hazard ratios associated with biomarker levels for 10-year coronary heart disease risk (n = 33 events) or total cardiovascular disease risk (n = 45 events).

RESULTS

At baseline, mean (sd) age was 62 years (7 years); 62 were men; and 43 had microalbuminuria. Soluble E-selectin demonstrated cross-sectional relationships with glucose and factor XIIa was related to plasminogen activator inhibitor-1 and triglycerides (all P < 0.05). Baseline log soluble E-selectin was significantly related to incident coronary heart disease and cardiovascular disease. Hazard ratios (95% CIs) associated with a 1-unit increase in log soluble E-selectin in age- and sex-adjusted models were: coronary heart disease : 4.6 (95% CI 1.9-11.3), P = 0.001; cardiovascular disease: 3.6 (95% CI 1.7-7.4, P = 0.001); and in multivariable-adjusted models were: coronary heart disease: 2.9 (95% CI 1.2-7.1, P = 0.02); cardiovascular disease: 2.3 (95% CI 1.1-4.8), P = 0.02. Factor XIIa was significantly related to incident cardiovascular disease. The hazard ratios associated with a 1-unit increase in factor XIIa in age- and sex-adjusted models was 1.5 (95% CI 1.1-1.9, P = 0.003) and in a multivariable-adjusted model was 1.3 (95% CI 1.0-1.6, P = 0.047). Plasminogen activator inhibitor-1 and thrombin-antithrombin III complex were not related to cardiovascular disease events.

CONCLUSIONS

In our study, soluble E-selectin and factor XIIa were significantly related to 10-year incident macrovascular events in patients with Type 2 diabetes. These preliminary findings call for replication in larger studies.

Non-invasive investigation of kidney disease in type 1 diabetes by magnetic resonance imaging

AIMS/HYPOTHESIS

Pathophysiological abnormalities in early diabetic nephropathy are poorly understood. We employed MRI to characterise renal perfusion, tissue oxygenation and kidney size in non-diabetic volunteers and type 1 diabetic patients without and with early renal disease.

METHODS

We studied ten control participants (C; age 40.0 [range 31-54] years), nine longstanding normotensive type 1 diabetic patients (T1Normo; age 40.1 [31-50] years, estimated glomerular filtration rate [eGFR] 83.4 ± 10.6 ml min(-1) 1.73 m(-2)) and eight microalbuminuric type 1 diabetic patients (T1Micro; age 42.4 [33-52] years, eGFR 71.6 ± 13.7 ml min(-1) 1.73 m(-2)). Six microalbuminuric patients were restudied after 4 weeks without renin-angiotensin-aldosterone system inhibitors. Phase contrast angiography and kidney blood oxygen level dependent (BOLD) (R(2)(*)) MRI were performed, before and during water diuresis. Contrast-enhanced MRI was performed at baseline urine flow rate. Renal artery flow, renal vascular resistance (RVR), cortical and medullary volumes, and R(2)(*) were determined.

RESULTS

Renal cortical and medullary volumes were similar in all groups (cortex: C 108 ± 16, T1Normo 112 ± 21, T1Micro 111 ± 10 cm(3)/1.73 m(2); medulla: C 35 ± 14, T1Normo 29 ± 10, 33 ± 6 cm(3)/1.73 m(2)). RVR increased from control to normoalbuminuric to microalbuminuric type 1 diabetic patients (C 0.061 ± 0.018, T1Normo 0.077 ± 0.014, T1Micro 0.093 ± 0.024 mmHg ml(-1) min(-1) 1.73 m(-2), ANOVA p = 0.012). RVR correlated inversely with eGFR in normoalbuminuric, but not in microalbuminuric diabetic patients. Renal artery flow was lower in the whole diabetes cohort (control 740 ± 205 vs diabetes 591 ± 128 ml min(-1) 1.73 m(-2), p = 0.035).

CONCLUSIONS/INTERPRETATION

Cortical and medullary volumes remain normal in early diabetic nephropathy. Decreased renal flow in longstanding normoalbuminuric type 1 diabetic patients may reflect intrarenal vascular stiffening, whereas in the microalbuminuric patients it may also reflect increased intraglomerular pressure.

The ARUBA trial: current status, future hopes

BACKGROUND AND PURPOSE

Report on the status of an on-going National Institutes of Neurological Disorders and Stroke (NINDS)-supported clinical trial of management of unbled brain arteriovenous malformations.

SUMMARY OF REVIEW

Begun in April 2007 with 3 centers, the trial has grown to 65 centers, and has randomized 124 patients through mid-June 2010 en route to the planned 400. The current literature continues to support the rationale for the trial.

CONCLUSIONS

ARUBA is steadily approaching its monthly randomization goals and has already reached the number needed to test the maximum published interventional complication rates against the minimum hemorrhage rates for natural history.

Intrauterine growth rate in pregnancies complicated by type 1, type 2 and gestational diabetes

Fetal macrosomia is a feature of all subtypes of maternal diabetes. The intrauterine time course of development of macrosomia in type 1, type 2 and gestational diabetes (GDM) could identify the times of more rapid growth, which differ as a result of different influences in subtypes of diabetes. Higher maternal weight in type 2 and GDM may be expected to contribute to macrosomia and the blood glucose control will exert an additional influence. Information was collected prospectively on 217 pregnancies in insulin-treated women at a single centre over a six-year period. All women were managed by a single team of obstetricians and diabetologists at a Joint Obstetric Medical Clinic. The rate of increase in abdominal circumference from 28 weeks was identical in each subtype of diabetes and there were no differences between subtypes at the earliest gestation assessed. Use of customized growth centiles showed rates of macrosomia to be similar in type 1, type 2 and GDM (43.0%, 50.0% and 41.8%, respectively). The intrauterine time course to macrosomia is similar in type 1, type 2 and GDM. The relationship of macrosomia to extent of elevation of mean blood glucose control is weak, implying a low threshold for maximal effect on the rate of fetal growth.

Genetic association analyses of non-synonymous single nucleotide polymorphisms in diabetic nephropathy

AIMS/HYPOTHESIS

Diabetic nephropathy, characterised by persistent proteinuria, hypertension and progressive kidney failure, affects a subset of susceptible individuals with diabetes. It is also a leading cause of end-stage renal disease (ESRD). Non-synonymous (ns) single nucleotide polymorphisms (SNPs) have been reported to contribute to genetic susceptibility in both monogenic disorders and common complex diseases. The objective of this study was to investigate whether nsSNPs are involved in susceptibility to diabetic nephropathy using a case-control design.

METHODS

White type 1 diabetic patients with (cases) and without (controls) nephropathy from eight centres in the UK and Ireland were genotyped for a selected subset of nsSNPs using Illumina's GoldenGate BeadArray assay. A chi (2) test for trend, stratified by centre, was used to assess differences in genotype distribution between cases and controls. Genomic control was used to adjust for possible inflation of test statistics, and the False Discovery Rate method was used to account for multiple testing.

RESULTS

We assessed 1,111 nsSNPs for association with diabetic nephropathy in 1,711 individuals with type 1 diabetes (894 cases, 817 controls). A number of SNPs demonstrated a significant difference in genotype distribution between groups before but not after correction for multiple testing. Furthermore, neither subgroup analysis (diabetic nephropathy with ESRD or diabetic nephropathy without ESRD) nor stratification by duration of diabetes revealed any significant differences between groups.

CONCLUSIONS/INTERPRETATION

The nsSNPs investigated in this study do not appear to contribute significantly to the development of diabetic nephropathy in patients with type 1 diabetes.

Are glomerular volume differences between type 1 and type 2 diabetic patients pathologically significant?

The observation that patients with type 2 diabetes tend to have larger glomeruli than patients with type 1 diabetes was first made more than 10 years ago. It has also been noted that type 2 diabetic patients with nephropathy often have more heterogeneous renal function and structure than type 1 patients. However, whether these observations are linked or have any bearing on the progression of nephropathy in the two types of diabetes remains uncertain. Here we put forward several hypotheses as to why glomerular volume in type 1 differs from that in type 2 diabetes. We suggest that although type 1 and type 2 diabetic patients appear to progress through similar stages of diabetic nephropathy, the route they take may differ. Differences in the way in which the glomeruli respond to the diabetic milieu may enable some type 2 diabetic patients to preserve their filtration surface in the face of an expanding mesangium.

The effect of intrauterine environment and low glomerular number on the histological changes in diabetic glomerulosclerosis

AIMS/HYPOTHESIS

We tested the hypothesis that diabetic glomerulosclerosis would develop more rapidly in animals with fewer glomeruli.

METHODS

We studied the female offspring of Wistar rats that had been fed a low-protein diet (LPD) containing 6% protein or a normal-protein diet (NPD) containing 18% protein during pregnancy. Streptozotocin diabetes was induced at 12 weeks and animals were killed at 40 weeks.

RESULTS

Non-diabetic LPD offspring were of lower birthweight than the NPD offspring (5.19+/-0.64 vs 6.45+/-0.67 g, p<0.001) and had fewer glomeruli (27,402+/-3,137 vs 34,203+/-6,471, p<0.05). Glomerular volume correlated inversely with glomerular number (r=-0.64, p=0.035), but total glomerular filtration surface area was reduced in the LPD animals (4,770+/-541 vs 5,779+/-1,302 mm(2), p=0.05). Other renal structural and functional parameters were similar. In LPD and NPD diabetic animals, glomerular volume and basement membrane width were significantly increased compared to their respective controls. Podocyte density was lowest in the LPD diabetic animals (not significant), and the area covered by each podocyte was greater in the LPD diabetic group (2.40+/-0.693 x10(-3) mm(2)) than in the LPD control group (1.68+/-0.374 x10(-3) mm(2), p<0.001) and in the NPD diabetic animals (1.71+/-0.291 x 10(-3) mm(2), p<0.05). There was no difference in any other structural or functional parameter between the LPD and NPD diabetic animals.

CONCLUSIONS/INTERPRETATION

A decrease in glomerular number was not deleterious to renal structure and function over 40 weeks in this animal model. Further work in models with progressive renal impairment and hypertension is necessary to clarify the impact of glomerular number on the development of renal disease.

The podocyte: a major player in the development of diabetic nephropathy?

Although abnormalities in the glomerular epithelial cell, the podocyte, have been appreciated for some time, it is only recently that their significance and the underlying mechanisms for the changes have begun to be explored. There is a decrease in podocyte number early in diabetes, with further decreases as albuminuria increases. The number of podocytes is inversely related to the degree of albuminuria in both cross-sectional and longitudinal studies. Foot process width is increased in proteinuria, the width correlating with albuminuria. Loss of nephrin - both mRNA and protein - occurs some time after the onset of diabetes and is also inversely related to proteinuria. The amount of the alpha3beta1 integrin on the basement-membrane surface of the foot process of the podocyte is also reduced in diabetes. Loss of nephrin and alpha3beta1 integrin is induced by both hyperglycaemia and mechanical stretch. Agents that inhibit the renin-angiotensin system, but not other agents that reduce proteinuria, restore nephrin expression and prevent the structural changes seen in the podocyte in diabetes. Thus, changes in the podocyte contribute to the proteinuria of diabetic nephropathy and can be ameliorated by inhibition of the renin-angiotensin system.

Recent advances in diabetic nephropathy

Diabetic nephropathy is the leading cause of end stage renal disease worldwide and is associated with increased cardiovascular risk. The earliest clinical manifestation is of microalbuminuria. Tight blood glucose and blood pressure control reduce the risk of microalbuminuria. Once microalbuminuria is present, the rate of progression to end stage renal disease and of cardiovascular disease can be delayed by aggressive management of blood pressure, glucose, and lipids. Inhibition of the renin-angiotensin system is important to reduce intraglomerular pressure but other classes of antihypertensive agent may also be needed to gain adequate control of systemic blood pressure. Such measures can at least half the rate of progression of nephropathy and cardiovascular disease.

Increasing neutrophil F-actin corrects CD11b exposure in Type 2 diabetes

BACKGROUND

Leukocyte dysfunction contributes to the pathogenesis of diabetic vascular complications. Neutrophils adhere to the endothelium through the beta(2)integrin CD11b/CD18. In Type 2 diabetes, neutrophil surface CD11b expression is increased and is associated with impaired actin polymerization. This study aimed to determine whether increasing neutrophil actin polymerization could correct the defect in CD11b exposure.

DESIGN

Neutrophil actin polymerization was stimulated with the tyrosine phosphatase inhibitor phenylarsine oxide (PAO), and cytoskeletal phosphotyrosine was monitored by immunoblotting Triton X-100 insoluble fractions of cells. Neutrophil F-actin was measured with phalloidin-FITC staining, and surface CD11b expression was determined with anti-CD11b-PE before analysis with flow cytometry.

RESULTS

Phenylarsine oxide caused an increase in phosphotyrosine in neutrophils from both patients with Type 2 diabetes (DM) and controls (NC) (-fold increase: NC, 1.43 +/- 0.16; DM, 1.46 +/- 0.10). The response to PAO in terms of phalloidin-binding was impaired in neutrophils from patients [phalloidin-FITC MFI area under the curve, NC 200 +/- 5 (x 10(3)), DM 124 +/- 9 (x 10(3)), P < 0.0001]. Phenylarsine oxide at concentrations < 10 micro mol L(-1) also caused loss of CD11b from neutrophil surfaces that was impaired in samples from patients [CD11b sites area under the curve NC 90 +/- 6 (x 10(3)), DM 121 +/- 9 (x 10(3)), P < 0.002]. However, in neutrophils from patients, incubation with PAO at a concentration of > 10 micro mol L(-1) caused a significant increase in intracellular F-actin and CD11b down-regulation equivalent to that observed in controls.

CONCLUSION

In Type 2 diabetes, impaired neutrophil actin polymerization even in response to increasing cytoskeletal phophotyrosine suggests a downstream defect. Furthermore, increasing actin polymerization, above a minimum threshold level, corrects the defect in integrin exposure. Correction of the actin polymerization defect in Type 2 diabetes could improve the prognosis of diabetic vascular complications.

Impaired neutrophil store-mediated calcium entry in Type 2 diabetes

BACKGROUND

In Type 2 diabetes impaired neutrophil function leads to increased bacterial infection and cardiovascular disease. Many neutrophil functions depend on calcium signalling, which involves release of calcium from intracellular stores and subsequently translocation of stores via the cytoskeleton to the plasma membrane, causing store-mediated calcium entry (SMCE) into the cell. We hypothesized that in Type 2 diabetes there would be a defect in SMCE.

MATERIALS AND METHODS

Neutrophils were prepared from patients with Type 2 diabetes (DM, n=15) and controls (NC, n=15). Free cytosolic calcium [Ca2+]i was measured with Fura-2 in resting cells and after stimulation of calcium release with fMLP and thapsigargin.

RESULTS

Baseline [Ca2+]i was higher in neutrophils from the patients than the controls (NC 65 +/- 5 nm, DM 80 +/- 4 nm, P<0.05). However, after fMLP-treatment [Ca2+]i was significantly lower in the patients (NC 301 +/- 28 nm, DM 210 +/- 20 nm, P<0.01). The greater increase in controls was not observed when cells were treated with fMLP in the absence of extracellular calcium (-fold increase NC 2.9 +/- 0.5, DM 2.7 +/- 0.3). Treatment of cells with thapsigargin caused a similar greater increase in [Ca2+]i in the controls than in the patients that was not seen in the absence of extracellular calcium (-fold increase with Ca2+ NC 5.2 +/- 1.0, DM 3.0 +/- 0.4, P<0.05; fold increase without Ca2+ NC 2.5 +/- 0.4, DM 2.2 +/- 0.2).

CONCLUSIONS

In Type 2 diabetes there is a defect in neutrophil calcium signalling which results in a lesser increase in free cytosolic calcium owing to impaired influx across the plasma membrane. Abnormal calcium signalling is likely to be important in the pathogenesis of diabetic complications.

Microalbuminuria is more frequent in South Asian than in European origin populations: a comparative study in Newcastle, UK

AIMS

We aimed to compare levels of urinary albumin excretion and the prevalence of microalbuminuria in UK South Asians and Europeans. Microalbuminuria predicts cardiovascular disease in European origin populations, but evidence from the general population of South Asians is lacking. Coronary heart disease (CHD) mortality is 40-50% higher in UK South Asians compared with the whole population, for reasons that are incompletely understood.

METHODS

Microalbuminuria was measured using the albumin-creatinine ratio in an age- and sex-stratified random sample of 1509 adults from European (n = 825), Indian (n = 259), Pakistani (n = 305) and Bangladeshi (n = 120) ethnic groups.

RESULTS

Levels of urinary albumin excretion were substantially higher in South Asians (geometric mean albumin creatinine ratio (95% confidence interval) 0.83 (0.75, 0.91)) than in Europeans (0.55 (0.51, 0.60)). Microalbuminuria was associated with older age, hypertension and diabetes, but independently of these risk factors urinary albumin excretion was higher in South Asians than Europeans.

CONCLUSIONS

Urinary albumin excretion is higher and microalbuminuria more frequent in UK South Asians compared with the majority ethnic population. Microalbuminuria may be relevant to the causal pathways leading to the excess of cardiovascular mortality and possibly renal failure in UK South Asians.

Impaired neutrophil actin assembly causes persistent CD11b expression and reduced primary granule exocytosis in Type II diabetes

AIMS/HYPOTHESIS

Neutrophil dysfunction has a role in the pathogenesis of complications in Type II (non-insulin-dependent) diabetes mellitus. Neutrophils adhere through expression of the beta(2)integrin CD11b/CD18 which closely associates with the actin cytoskeleton. The aim of this study was to investigate the effect of actin polymerisation on CD11b expression and exocytosis of the primary granule marker CD69 in neutrophils from patients with Type II diabetes.

METHODS

Neutrophils were activated with fMLP or PMA, actin polymerisation was inhibited with cytochalasin D. Cells were stained for CD11b and CD69 expression and intracellular F-actin was measured with phalloidin-FITC. Cellular fluorescence was measured by flow cytometry. Actin content of Triton X-100 fractions of cells was measured by SDS-PAGE and Coomassie blue staining.

RESULTS

PMA caused an increase in neutrophil F-actin that was greater in control subjects than in patients with Type II diabetes (50.8% vs 33.4%, p<0.001) and correlated with actin integrated optical density (IOD) by SDS-PAGE ( r=0.74, p=0.01). Loss of CD11b from cell surfaces only occurred in neutrophils with high F-actin. The proportion of cells losing CD11b was lower in patients than in control subjects (23.1% vs 37.5%, p<0.001) and lowest in patients with additional cardiovascular risk markers (20.1% vs 27.7%; p<0.05). Cytochalasin D prevented loss of CD11b ( p<0.001). CD69 expression was reduced in patients with Type II diabetes (22.6% vs 36.4%, p<0.001) and correlated with F-actin content ( r=0.78, p<0.0001).

CONCLUSION/INTERPRETATION

In Type II diabetes impaired neutrophil actin polymerisation leads to persistent expression of CD11b and reduced exocytosis of primary granules and could contribute to the pathogenesis of diabetic complications.

Clinical outcomes of pregnancy in women with type 1 diabetes(1)

OBJECTIVE

To evaluate predictors of neonatal hypoglycemia and macrosomia in 107 consecutive pregnancies in type 1 diabetic women.

METHODS

We conducted a case record analysis of singleton type 1 diabetic pregnancies between January 1994 and January 1999 following institution of standardized management.

RESULTS

The duration of diabetes in the women was 12.9 +/- 6.8 years, and 44 were primigravidas. The mean HbA1c throughout pregnancy was 7.2 +/- 0.8%. There was no relationship between neonatal blood glucose (checked before the second feed) and HbA1c at any point in pregnancy or mean pregnancy HbA1c (R = 0.20, P >.1). However, there was a negative correlation between neonatal blood glucose and maternal blood glucose during labor (R = -0.33, P <.001). When maternal blood glucose during labor was greater than 8 mM (144 mg/dL), neonatal blood glucose was usually less than 2.5 mM (mean 1.7 +/- 0.4 mM or 31 mg/dL). There was no relationship between mean HbA1c and birth weight (R = 0.02, P >.1) or between maximum insulin dose and birth weight (R = 0.09, P >.1). Fetal abdominal circumference measured by ultrasound at 34 weeks correlated strongly with birth weight (R = 0.72, P <.001).

CONCLUSION

Neonatal hypoglycemia correlates with maternal hyperglycemia in labor, not with HbA1c during pregnancy. Macrosomia does not correlate with HbA1c during pregnancy.

Audit of influenza and pneumococcal vaccination uptake in diabetic patients attending secondary care in the Northern Region

AIMS

To document uptake of influenza and pneumococcal vaccination in diabetic patients attending secondary care in the Northern Region, and to explore influencing factors.

METHODS

Diabetic patients attending out-patients in Middlesbrough, Gateshead and Newcastle were questioned from October 1999 to March 2000. Physicians inquired about influenza and pneumococcal vaccination status using a standardized questionnaire. Data collected included age, year of diagnosis, duration of diabetes, type of diabetes, and the presence of other recognized indications for vaccination.

RESULTS

Two hundred and sixty-eight diabetic patients, 42% (113/268) with Type 1 diabetes, 34% (91/268) with ischaemic heart disease, 10% (26/268) with chronic pulmonary disease (CPD) and 10% (27/268) with chronic renal disease, were questioned. Thirty-five percent (93/268) of patients received both influenza and pneumococcal vaccines, 24% (64/268) received only influenza vaccine, and none received pneumococcus vaccine alone. Most vaccinees received advice about influenza and pneumococcal vaccination from their general practitioner (90% (142/157) and 87% (81/93), respectively). A large number of non-vaccinees were unaware of the need for influenza and pneumococcal vaccination (69% (76/111) and 91% (159/175), respectively). Using multiple logistic regression co-existing CPD increased the odds of receiving influenza (odds ratio (OR) (95% confidence interval (CI)) = 1.99 (1.07-14.12)) or pneumococcal (OR = 3.77 (1.69-21.76)) vaccination. Furthermore, each 1-year increase in age increased the chance of receiving influenza or pneumococcal vaccination by 22% (OR = 1.22 (1.09-1.67) and 29% (OR = 1.29 (1.07-1.72)), respectively.

CONCLUSIONS

Vaccination rates in these diabetic patients are unsatisfactory. Secondary care health professionals might increase rates by raising the topic in consultations. Diabet. Med. 18, 599-603 (2001)

Intra-uterine environment influences glomerular number and the acute renal adaptation to experimental diabetes

AIMS/HYPOTHESIS

We sought to test the hypothesis of whether low birth weight rats would have reduced glomerular number, higher systolic blood pressure and an altered acute response to streptozotocin diabetes compared to normal birth weight rats.

METHODS

Female offspring of Wistar rats fed an isocaloric diet containing either 6% casein (LPD) or 18% casein (NPD) in utero were studied. Birth weight, body weight, systolic blood pressure and urine albumin excretion were measured before and after streptozotocin diabetes. Glomerular number and volume were estimated after one week of diabetes.

RESULTS

The LPD rats were of low birth weight (5.4 +/- 0.5 g vs 6.4 +/- 0.8 g, p < 0.0001) with higher systolic blood pressure (137 +/- 9mmHg vs 120 +/- 7 mmHg, p < 0.0001) and reduced glomerular number (17,435 +/- 2,074 vs 24,846 +/- 1,864, p < 0.0001). The LPD rats had smaller kidneys (0.925 +/- 0.009 g vs 1.200 +/- 0.173 g, p = 0.041) but similar glomerular volume to NPD control rats (1.11 +/- 0.15 x 10(6) microm3 vs 1.08 +/- 0.17 x 10(6) microm3). After 1 week of diabetes LPD rats had a greater proportional increase in renal size (diabetes 50 +/- 12 % vs control 20 +/- 4%, p = 0.003). Insulin suppressed renal hypertrophy in both LPD and NPD rats but failed to suppress glomerular hypertrophy in LPD rats (1.48 +/- 0.21 x 10(6) microm3 vs 1.03 +/- 0.23 x 10(6) microm3 p = 0.015).

CONCLUSION/INTERPRETATION

Abnormal intra-uterine environment reduces both renal size and glomerular number and influences the acute renal adaptation to experimental diabetes.

Birth weight has no influence on glomerular number and volume

It has been proposed that low birth weight (LBW) results in a reduction in glomerular number that may, in turn, predispose an individual to develop hypertension in adulthood. Glomerular number is reduced in animal models of intra-uterine malnutrition using a variety of techniques. However, the relevance of such extreme models to man is uncertain. The purpose of this study was to evaluate whether animals with naturally occurring LBW, which have not received any manipulation in utero, have a reduction in glomerular number, altered glomerular volume and abnormal urine albumin excretion. Litters from female rats delivering at term on the same day were weighed and sexed at birth. From each litter 2 males with the lowest birth weight (LBW n = 18) and 2 males with a birth weight closest to the litter mean [normal birth weight (NBW) n = 18] were selected and cross-fostered onto periparturient lactating dams. LBW rats weighted 6.7 +/- 0.6 g compared with 7.2 +/- 0.6 g for NBW rats (P = 0.03). After weaning all rats were weighed weekly and underwent metabolic studies at 4, 8, 12 and 16 weeks. Following perfusion fixation, glomerular number and mean glomerular volume were estimated using standard stereological techniques. There was no significant difference between LBW and NBW rats with respect to glomerular number (24,499 +/- 2,078 vs. 24,825 +/- 1,818), mean glomerular volume and urine albumin excretion, and no rats had a glomerular number outside the normal range. This study suggests that naturally occurring LBW has little influence on renal development, glomerular number and volume.

Abnormal thiol group modulation of sodium-lithium countertransport and membrane fluidity is associated with a disturbed relationship between serum triacylglycerols and membrane function in type II diabetes

In essential hypertension and diabetic nephropathy, sodium-lithium countertransport (Na-Li CT) is an inherited marker, subject to metabolic influences, of cardiovascular risk. Studies in Type II diabetes, taking clinical phenotypes as their starting point, are conflicting. We sought to identify Na-Li CT kinetic abnormalities in Type II diabetes, and only subsequently to seek relationships with clinical variables. Na-Li CT kinetics, membrane fluidity and their modulation by thiol proteins were measured in erythrocytes from 38 patients with Type II diabetes and in 16 normal control subjects. In untreated erythrocytes, Na-Li CT kinetics were similar. Thiol protein alkylation with N-ethylmaleimide generally caused both V(max) and K(m) to fall, but caused K(m) to rise in erythrocytes from 13 out of 38 diabetic subjects, whose native K(m) was low (P=0. 0013 compared with control). V(max) and serum triacylglycerol levels were related in normal controls (r(s)=0.54, P=0.038) and in diabetic subjects whose K(m) fell after N-ethylmaleimide (n=25, r(s)=0.62, P=0.001). Where the K(m) rose after N-ethylmaleimide, V(max) and triacylglycerol levels were not related (n=13, r(s)=-0.39, P=0.183) and membrane fluidity did not increase after N-ethylmaleimide. However, these subgroups were indistinguishable in terms of blood pressure, albuminuria, glycaemia or lipid profiles. Thus abnormalities in the regulation of Na-Li CT and membrane fluidity by key thiol proteins, resembling those seen in essential hypertension and diabetic nephropathy, were apparent in one-third of subjects with Type II diabetes. Membrane abnormalities may indicate a common pathological mechanism. The prognostic significance of Na-Li CT kinetic abnormalities in Type II diabetes must now be confirmed.

Increased left ventricular mass index and nocturnal systolic blood pressure in patients with Type 2 diabetes mellitus and microalbuminuria

AIMS

To compare left ventricular mass (LVM) index and function in patients with Type 2 diabetes mellitus with and without microalbuminuria and to investigate the clinical determinants of left ventricular hypertrophy.

METHODS

Echocardiography, electrocardiography and 24-h ambulatory blood pressure monitoring were performed in microalbuminuric (n = 29) and normoalbuminuric (n = 29) patients with Type 2 diabetes and no clinical evidence of heart disease. Groups were individually matched for age, sex and diabetes duration and smoking status.

RESULTS

LVM index (62 (34-87) vs. 52 (33-89) g/m2.7, P = 0.04) and LVH prevalence, using two out of three definitions, were greater in patients with microalbuminuria (LVM/height2.7: 72 vs. 59%, P = 0.27, LVM/height: 66 vs. 38%, P = 0.04, LVM/body surface area: 59 vs. 31%, P = 0.03). Night-time systolic blood pressure (126 (99-163) vs. 120 (104-157) mmHg, P = 0.005) and the night/day systolic blood pressure ratio (0.92 (0.08) vs. 0.88 (0.06), P = 0.04) were higher in those with microalbuminuria. Systolic and diastolic function were similar in both groups. Linear regression analyses showed that body mass index (BMI) was significantly related to loge LVM index (R2 = 11.8%, P = 0.005) and a relationship with night/day systolic blood pressure was also suggested (R2 = 4.6%, P = 0.057).

CONCLUSIONS

In patients with Type 2 diabetes, LVH is more common and severe in those with microalbuminuria. Its presence may be related to raised night/day systolic blood pressure ratio and is significantly related to BMI. The high prevalence of LVH strengthens the case for echocardiographic screening in Type 2 diabetes to identify high risk patients who might benefit from aggressive cardiovascular risk factor intervention.

Rapid identification of Campylobacter, Arcobacter, and Helicobacter isolates by PCR-restriction fragment length polymorphism analysis of the 16S rRNA gene

A rapid two-step identification scheme based on PCR-restriction fragment length polymorphism (PCR-RFLP) analysis of the 16S rRNA gene was developed in order to differentiate isolates belonging to the Campylobacter, Arcobacter, and Helicobacter genera. For 158 isolates (26 reference cultures and 132 clinical isolates), specific RFLP patterns were obtained and species were successfully identified by this assay.

Episodic hyperglycaemia in pregnant women with well-controlled Type 1 diabetes mellitus: a major potential factor underlying macrosomia

AIMS

To test the common assumption that pregnant women who are sufficiently motivated to achieve very good HbA1c levels will record home blood glucose data accurately.

METHODS

A new device was used to download information from electronic blood glucose meters to assess the extent of selectivity in patient glucose diary-keeping.

RESULTS

In an index case, a woman with excellent ambient HbA1c (5.9%; upper limit of normal 6.1%) was observed to have 68% of preprandial blood glucose readings above the target range of 3.5-6.5 mmol/l and a mean (+/- SD) level of 8.9+/-3.9 mmol/l in the corresponding period. No such impression was conveyed by the home monitoring diary. Six pregnant women with well controlled Type 1 diabetes (mean HbA1c 6.6+/-0.2%) exhibited between 42 and 68% of preprandial readings above the target range.

CONCLUSIONS

The frequency of hyperglycaemia has hitherto been underestimated in well controlled pregnant women whose near-perfect home monitoring record is apparently corroborated by near-normal HbA1c levels. These observations provide a hypothesis for understanding of the disappointing continuance of macrosomia despite excellent HbA1c levels throughout pregnancy.

Dysregulation of PMN antigen expression in Type 2 diabetes may reflect a generalized defect of exocytosis: influence of hypertension and microalbuminuria

Defective exocytosis could underlie clinical and metabolic abnormalities in Type 2 diabetes. Because many SNARE proteins appear to be common mediators of exocytosis, we examined phorbol myristate acetate-stimulated expression of CD11b and CD69 on polymorphonuclear leukocytes (PMN) from Type 2 diabetic subjects with hypertension and microalbuminuria (D-htma), hypertension only (D-ht) or uncomplicated (D-uc), and normal controls (NC) by flow cytometry. CD11b expression was rapid (half maximal by 7 min), initially on all PMN. CD69 expression took place subsequently but on PMN that did not express CD11b. The proportion of CD11b-positive PMN at 30 min was higher in all diabetic groups than in NC. Expression of CD11b was higher and CD69 lower in D-uc and D-htma but were similar in NC and D-ht. In Type 2 diabetes the transition from the CD11b-positive to CD69-positive state is impaired. The defect in the process of CD69 expression appeared most marked in diabetic subjects with hypertension and microalbuminuria.

Blood pressure control, microalbuminuria and cardiovascular risk in Type 2 diabetes mellitus

Type 2 (noninsulin-dependent) diabetes mellitus (DM) affects about 3% of the UK population. Diabetes often coexists with a cluster of other potent cardiovascular risk factors, including hypertension, dyslipidaemia and increased tendency for thrombosis, and increases the risk of early death from cardiovascular causes by about threefold. Microalbuminuria or proteinuria also may be present, further increasing the risk of cardiovascular mortality. Cardiovascular risk factors must be treated aggressively in patients with Type 2 diabetes and control of blood pressure at 140/85 mm Hg or lower is a priority. The management of hypertension in patients from some ethnic groups demands special consideration because they have a high incidence of diabetes and hypertensive complications. Patients must be urged to adopt appropriate lifestyle changes in the first instance but additional drug treatment for hypertension is usually required. All the major classes of antihypertensive agents lower blood pressure in Type 2 diabetic patients but have different effects on metabolic risk factors in different ways. Low-dose thiazide diuretics, beta-blockers, calcium channel blockers and angiotensin converting enzyme (ACE) inhibitors have been shown to reduce cardiovascular risk. Individually, the effects of low-dose thiazide diuretics and beta-blockers on glucose and lipid metabolism is clinically insignificant, though in combination much larger metabolic effects are seen. ACE inhibitors and calcium channel blockers have no, or small, beneficial effects on glucose and lipid metabolism, while the greater beneficial effects of alpha1-blockers on lipid profiles may render them especially useful in the Type 2 diabetic patient. Long-acting calcium-channel blockers and ACE inhibitors protect renal function and are suitable as first line therapy in patients with microalbuminuria or proteinuria. Until results from the current batch of randomized, placebo-controlled trials comparing different classes of antihypertensive agents are available, the choice of antihypertensive agent is difficult. Addressing overall cardiovascular risk factors, rather than hypertension alone, is essential in the management of the hypertensive Type 2 diabetic patient.

Silent myocardial ischemia and microalbuminuria in asymptomatic subjects with non-insulin-dependent diabetes mellitus

Microalbuminuria is an increase in urinary albumin not detected by conventional dipstick testing and is present in 20% of patients with non-insulin-dependent diabetes mellitus (NIDDM). Mortality in NIDDM patients with microalbuminuria is 60% at 8 years and is mainly due to cardiovascular disease. Because many deaths occur without warning symptoms, we have compared the prevalence and severity of silent myocardial ischemia in asymptomatic NIDDM patients with and without microalbuminuria. We have performed a cross-sectional, case-control study of asymptomatic NIDDM patients attending hospital diabetes clinics. Forty-three patients with microalbuminuria were matched for age, gender, diabetes duration, and smoking status with 43 normoalbuminuric patients. A symptom-limited exercise stress test was performed and reported blind to patient status. The degree of electrocardiographic ST-segment depression, exercise time, work performed, and maximum heart rate with exercise were recorded. Patients with microalbuminuria had a higher prevalence of ischemic response (>1 mm ST depression) (65% vs 40%, p = 0.016), reduced total exercise time (5 vs 7 minutes, p <0.001), reduced work (6 vs 8 METs, p <0.001), and reduced age-predicted maximum heart rate (94% vs 101%, p = 0.004). In multiple logistic regression, albumin excretion rate was shown to be the strongest independent predictor of ischemic response (p = 0.03). Silent myocardial ischemia is common in asymptomatic NIDDM patients but is more common in those with microalbuminuria. In these subjects, the higher prevalence of ischemic response at low workloads suggests a higher probability of future coronary events, and possibly a higher probability of potentially treatable coronary artery disease.

Autonomic neuropathy in asymptomatic subjects with non-insulin-dependent diabetes mellitus and microalbuminuria

Patients with non-insulin-dependent diabetes mellitus (NIDDM) and microalbuminuria (MA) are at increased risk of early death. In NIDDM patients without evidence of heart disease, we examined the links between MA and autonomic neuropathy (AN) and reduced heart rate variability (HRV), both of which have been linked to a poor prognosis. We have studied 43 asymptomatic NIDDM patients with MA and have matched them with 43 normoalbuminuric patients for age, gender, diabetes duration, and smoking status. AN was assessed by heart rate changes to deep breathing, Valsalva, and posture and blood pressure changes to posture and hand grip. Twenty-four hour Holter monitoring was used to evaluate HRV. Patients with MA showed evidence of AN and reduced HRV when compared with normoalbuminuric patients. In multivariate analysis, with measures of AN and HRV as outcome variables, Log albumin excretion rate was a significant independent predictor but stronger predictors were the presence of diabetic retinopathy, age, body mass index, claudication, alcohol consumption, and calcium channel blocker use. The presence of MA is linked to AN and reduced HRV in asymptomatic NIDDM patients. The nature of the relationship is complex, involving multiple relationships with other clinical parameters.

British Diabetic Association guidelines on genetic and immune screening for type 1 diabetes mellitus

The following article is a report from the Chairman of the Professional Advisory Committee of the British Diabetic Association. The committee, with the help of a number of experts currently working in the field, produced a set of guidelines intended for use by health care professionals on the issues around genetic screening for Type 1 diabetes mellitus. The guidelines were approved by the Board of Management of the British Diabetic Association and we publish them here.

Abnormal regulation of cell membrane fluidity in diabetic nephropathy

An abnormality of the physical properties of the cell membrane may underlie the defect that unites the clinical and biochemical abnormalities found in subjects with diabetic nephropathy. The cell membrane is linked both structurally and functionally with the cytoskeleton. The fluorescence anisotropy, a measure of membrane fluidity, was studied at baseline and after modulation of cytoskeletal proteins by thiol group alkylation with N-ethylmaleimide (NEM). 1,6-diphenyl-1,3,5-hexatriene (DPH) was used to assess anisotropy in the deep hydrophobic regions of the lipid bilayer and trimethylammonium-diphenylhexatriene (TMA-DPH) was used to assess the superficial, relatively hydrophilic regions. We compared 17 subjects with insulin-dependent diabetes mellitus (IDDM) and nephropathy with 17 control subjects with IDDM and 24 non-diabetic control subjects. Median TMA-DPH anisotropy (0.271 (0.239-0.332) vs 0.269 (0.258-0.281) vs 0.275 (0.246-0.287)) and DPH anisotropy (0.221 (0.193-0.261) vs 0.227 (0.197-0.253) vs 0.226 (0.193-0.245)) were similar in erythrocytes from the three groups. However after alkylation of protein thiol groups with NEM clear differences emerged. In the control subjects with and without IDDM there was a significant fall in TMA-DPH anisotropy compared to the subjects with diabetic nephropathy in whom the addition of NEM had no effect (deltaTMA-DPH anisotropy -0.005 (-0.020 - +0.006) vs -0.005 (-0.011 - +0.016) vs +0.002 (-0.010 - +0.008) p < 0.001). This finding was confirmed when the deep regions of the lipid bilayer were assessed using DPH (deltaDPH anisotropy -0.017 (-0.029 - -0.007.) vs -0.015 (-0.029 - +0.001) vs + 0.003 (-0.021 - +0.018) p < 0.001). We conclude that cytoskeletal modulation of the physical properties of the cell membrane lipids by proteins is abnormal in subjects with diabetic nephropathy. Such an abnormality could explain some of the clinical and metabolic abnormalities found in this condition.

Renal autoregulation is normal in newly diagnosed, normotensive, NIDDM patients

Abnormalities of renal autoregulation with glomerular hyperfiltration and raised intraglomerular pressure have been suggested as important factors in the initiation and development of diabetic nephropathy. Angiotensin converting enzyme (ACE) inhibition appears to have a specific reno-protective role in diabetic nephropathy, possibly by reducing intraglomerular pressure. The acute effects of ACE inhibition on renal haemodynamics in normotensive, non-insulin-dependent diabetes mellitus (NIDDM) have not been previously reported. We measured simultaneous glomerular filtration rate (GFR) and renal plasma flow (RPF) in 29 (4 female) subjects, mean age 52 years (range 27-70), using 51Cr EDTA and 125I Hippuran. Clearances were corrected to 1.73 m(-2). All patients were normotensive (blood pressure < 75th centile for age and sex), newly diagnosed (< 30 days), taking no antihypertensive or hypoglycaemic medication. Subjects were randomly allocated (double blind) to receive the ACE inhibitor trandolapril 4mg day(-1) (H) (hypotensive dose), trandolapril 0.5 mg day(-1)(L) (non-hypotensive dose) or placebo (P) for 10 days after which renal haemodynamics were remeasured. For all subjects baseline GFR, RPF and filtration fraction (FF) were 97+/-21 ml min(-1) mean+/-SD, 439+/-120 ml min(-1) and 22.3+/-2.9 % respectively. Glomerular hyperfiltration (GFR> 120 ml min[-1]) was only demonstrated in 3 subjects (10.3 %). In group H mean arterial pressure (103+/-8 vs 93+/-9 mmHg, p < 0.001) and FF (23.8+/-2.3 vs 20.0+/-4.0%, p = 0.03) fell while RPF increased (376+/-111 vs 426+/-60 ml min(-1), p = 0.02), there was no significant change in GFR. No significant change in mean arterial pressure, GFR, RPF or FF occurred in groups P and L. These studies suggest that in newly diagnosed normotensive NIDDM subjects normal renal autoregulation occurs and glomerular hyperfiltration is uncommon.

Lack of association of angiotensin II type 1 receptor gene polymorphism with diabetic nephropathy in insulin-dependent diabetes mellitus

Several observations suggest that inherited factors are influential in the development of nephropathy in patients with insulin-dependent diabetes mellitus (IDDM). Genetic components of the renin angiotensin system are possible candidate genes. The aim of this study was to determine the role of the hypertension associated angiotensin II type 1 receptor (AT1R) gene A1166C polymorphism in susceptibility to nephropathy in IDDM. We examined 264 Caucasoid patients with IDDM and overt nephropathy (as defined by persistent proteinuria in the absence of other causes, hypertension and retinopathy), 136 IDDM patients with long duration of diabetes and no nephropathy (LDNN group), 200 recently diagnosed IDDM patients (Sporadic Diabetic group), and 212 non-diabetic subjects. The AT1R gene polymorphism was assessed using the polymerase chain reaction and restriction isotyping. Genotype frequencies did not differ significantly between the sporadic diabetic group and the nephropathy group (p = 0.245), nor between the long duration non-nephropathy group and the nephropathy group (p = 0.250). Allele frequencies were not significantly different between the three groups (p = 0.753). We conclude that there is no significant association between the hypertension associated AT1R gene polymorphism and diabetic nephropathy in patients with IDDM in the UK.