Normalization of intracellular calcium: a sweet solution to neutrophil dysfunction in diabetes?

Socio-epidemiological and land cover risk factors for melioidosis in Kedah, Northern Malaysia

BACKGROUND

Melioidosis, a fatal infectious disease caused by Burkholderia pseudomallei, is increasingly diagnosed in tropical regions. However, data on risk factors and the geographic epidemiology of the disease are still limited. Previous studies have also largely been based on the analysis of case series data. Here, we undertook a more definitive hospital-based matched case-control study coupled with spatial analysis to identify demographic, socioeconomic and landscape risk factors for bacteremic melioidosis in the Kedah region of northern Malaysia.

METHODOLOGY/PRINCIPAL FINDINGS

We obtained patient demographic and residential information and clinical presentation and medical history data from 254 confirmed melioidosis cases and 384 matched controls attending Hospital Sultanah Bahiyah (HSB), the main tertiary hospital of Alor Setar, the capital city of Kedah, during the period between 2005 and 2011. Crude and adjusted odds ratios employing conditional logistic regression analysis were used to assess if melioidosis in this region is related to risk factors connected with socio-demographics, various behavioural characteristics, and co-occurring diseases. Spatial clusters of cases were determined using a continuous Poisson model as deployed in SaTScan. A land cover map in conjunction with mapped case data was used to determine disease-land type associations using the Fisher's exact test deploying simulated p-values. Crude and adjusted odds ratios indicate that melioidosis in this region is related to gender (males), race, occupation (farming) and co-occurring chronic diseases, particularly diabetes. Spatial analyses of disease incidence, however, showed that disease risk and geographic clustering of cases are related strongly to land cover types, with risk of disease increasing non-linearly with the degree of human modification of the natural ecosystem.

CONCLUSIONS/SIGNIFICANCE

These findings indicate that melioidosis represents a complex socio-ecological public health problem in Kedah, and that its control requires an understanding and modification of the coupled human and natural variables that govern disease transmission in endemic communities.

The effect of diabetes mellitus on organ dysfunction with sepsis: an epidemiological study

Introduction

Diabetes mellitus (DM) is one of the most common chronic co-morbid medical conditions in the USA and is frequently present in patients with sepsis. Previous studies reported that people with DM and severe sepsis are less likely to develop acute lung injury (ALI). We sought to determine whether organ dysfunction differed between people with and without DM and sepsis.

Methods

Using the National Hospital Discharge Survey US, sepsis cases from 1979 to 2003 were integrated with DM prevalence from the Centers for Disease Control and Prevention (CDC) Diabetes Surveillance System.

Results

During the study period 930 million acute-care hospitalisations and 14.3 million people with DM were identified. Sepsis occurred in 12.5 million hospitalisations and DM was present in 17% of patients with sepsis. In the population, acute respiratory failure was the most common organ dysfunction (13%) followed by acute renal failure (6%). People with DM were less likely to develop acute respiratory failure (9% vs. 14%, p < 0.05) and more likely to develop acute renal failure (13% vs. 7%, p < 0.05). Of people with DM and sepsis, 27% had a respiratory source of infection compared with 34% in people with no DM (p < 0.05). Among patients with a pulmonary source of sepsis, 16% of those with DM and 23% of those with no DM developed acute respiratory failure (p < 0.05); in non-pulmonary sepsis acute respiratory failure occurred in 6% of people with DM and 10% in those with no DM (p < 0.05).

Conclusions

In sepsis, people with diabetes are less likely to develop acute respiratory failure, irrespective of source of infection. Future studies should determine the relationship of these findings to reduced risk of ALI in people with DM and causative mechanisms.

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.

Diabetic patients have a decreased incidence of acute respiratory distress syndrome

OBJECTIVE

Our ability to predict which critically ill patients will develop acute respiratory distress syndrome (ARDS) is imprecise. Based on the effects of diabetes mellitus on the inflammatory cascade, we hypothesized that a history of diabetes might alter the incidence of ARDS.

DESIGN

A prospective multicenter study.

SETTING

Intensive care units at four university medical centers.

PATIENTS

One hundred thirteen consecutive patients with septic shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All patients were prospectively followed during their intensive care course for the development of ARDS. A history of diabetes was identified in 28% (32/113) of the patients. In this study, nondiabetics were more likely to develop septic shock from a pulmonary source (48%, 39/81) compared with diabetics (25%, 8/32) (p = .02). Forty-one percent (46/113) of the patients with septic shock developed ARDS. Forty-seven percent of the nondiabetic patients developed ARDS compared with only 25% of those with diabetes (p = .03, relative risk = 0.53, 95% confidence interval = 0.28-0.98). In a multivariate logistic regression analysis, when we adjusted for several variables including source of infection, the effect of diabetes on the incidence of ARDS remained significant (p = .03, odds ratio = 0.33, 95% confidence interval = 0.12-0.90).

CONCLUSIONS

In patients with septic shock, a history of diabetes is associated with a lower risk of developing ARDS compared with nondiabetics.