Magnetic resonance imaging and characterization of normal and abnormal intracranial cerebrospinal fluid (CSF) spaces

Summary A retrospective review of twenty-five normal MRI brain studies performed with the spin-echo technique focused special attention on the ventricular and extraventricular cerebrospinal fluid (CSF) and revealed unique signal intensity characteristics in the two locations. In addition, MRI studies of ten patients with abnormal extraaxial fluid collections either missed with CT or indistinguishable from CSF on CT images were also analyzed. MRI is more sensitive when compared to CT in evaluating the composition of CSF. Unique signal intensity characterizes the two major CSF compartments and presumably reflects their known but subtle difference in protein concentration (10–15 mg%). Normal variant or abnormal developmental fluid collections can be better characterized with MRI than with CT. These preliminary observations are offered in view of their implications for patient management and suggest further investigation.     

Antepartum predictors of the development of type 2 diabetes in Latino women 11-26 months after pregnancies complicated by gestational diabetes

In this study, we sought to identify antepartum characteristics that predict the de novo development of diabetes 11-26 months after the index pregnancy in a carefully characterized cohort of women with gestational diabetes mellitus (GDM). Oral and frequently sampled intravenous glucose tolerance tests (OGTTs and FSIGTs), hyperinsulinemic-euglycemic clamps with labeled glucose, and body composition studies were performed on 91 islet cell antibody-negative Latino women with GDM during the third trimester of pregnancy. The women were documented to be diabetes-free within 6 months postpartum. Their diabetes status was ascertained again between 11 and 26 months postpartum. Logistic regression analysis was used to identify independent predictors of the development of diabetes within that interval. Fourteen of the women developed diabetes by World Health Organization criteria 11-26 months after delivery of the index pregnancy. Three antepartum variables were independent predictors of diabetes: the 1-h postchallenge plasma glucose concentration from the 100-g OGTT at which GDM was diagnosed (higher = increased risk; P = 0.003); an index of pancreatic beta-cell compensation for insulin resistance, defined as the product of the 30-min incremental plasma insulin:glucose ratio on a 75-g OGTT and the insulin sensitivity index from a hyperinsulinemic-euglycemic clamp (lower = increased risk, P = 0.009); and the basal glucose production rate after an overnight fast (higher = increased risk; P = 0.04). We conclude that postchallenge hyperglycemia, poor pancreatic beta-cell compensation for insulin resistance, and elevated endogenous glucose production during pregnancy precede the development of type 2 diabetes in young Latino women by at least 1-2 years.     

Multiple metabolic defects during late pregnancy in women at high risk for type 2 diabetes

Detailed metabolic studies were carried out to compare major regulatory steps in glucose metabolism in vivo between 25 normal pregnant Latino women without and 150 pregnant Latino women with gestational diabetes mellitus (GDM). The two groups were frequency-matched for age, BMI, and gestational age at testing in the third trimester. After an overnight fast, women with GDM had higher fasting plasma glucose (P = 0.0001) and immunoreactive insulin (P = 0.0003) concentrations and higher glucose production rates (P = 0.01) but lower glucose clearance rates (P = 0.001) compared with normal pregnant women. During steady-state hyperinsulinemia (approximately 600 pmol/l) and euglycemia (approximately 4.9 mmol/l), women with GDM had lower glucose clearance rates (P = 0.0001) but higher glucose production rates (P = 0.0001) and plasma free fatty acid (FFA) concentrations (P = 0.0002) than the normal women. These intergroup differences persisted when a subgroup of 116 women with GDM who were not diabetic < or = 6 months after pregnancy were used in the analysis. When all subjects were considered, there was a very close correlation between glucose production rates and plasma FFA concentrations throughout the glucose clamps in control (r = 0.996) and GDM (r = 0.995) groups. Slopes and intercepts of the relationships were nearly identical, suggesting that blunted suppression of FFA concentrations contributed to blunted suppression of glucose production in the GDM group. In addition to these defects in insulin action, women with GDM had a 67% impairment of pancreatic beta-cell compensation for insulin resistance compared with normal pregnant women. These results demonstrate that women with GDM have multiple defects in insulin action together with impaired compensation for insulin resistance. Our findings suggest that defects in the regulation of glucose clearance, glucose production, and plasma FFA concentrations, together with defects in pancreatic beta-cell function, precede the development of type 2 diabetes in these high-risk women.     

Comparison of point-of-care-testing glucose meters with standard laboratory measurement of the 50g-glucose-challenge test (GCT) during pregnancy

OBJECTIVES: Although glucose meters are well-established instruments for self-monitoring blood glucose levels, diagnostic and screening procedures should be performed using standard laboratory methods. In addition to standard laboratory methods, HemoCue is authorized for screening and diagnostic purposes in Germany. The rapid development of other glucose meters makes it necessary to re-evaluate this recommendation. Our objective was to test the usefulness of glucose meters in screening pregnant patients for gestational diabetes. METHODS: The 50-g glucose challenge test was administered to one hundred and ninety-three pregnant patients whose blood glucose levels were then simultaneously measured with five portable meters and the HemoCue. The results were compared to our standard method (Hexokinase). A cut-off of 7.8 mmol/L was used and sensitivity, specificity, accuracy, the Youden index, and the Kappa index were calculated. The tests were performed by well-trained personnel (C.D. and U.S.). RESULTS: 1212 measurements were performed on 193 patients. All glucose meters showed a very good correlation (r > 0.90). None of the measurements showed an extreme deviation necessitating the error grid analysis. The GlucoTouch (5.93% +/- 7.4) and the HemoCue (-9.04% +/- 5.9) showed a mean deviation greater than 5%. None of the meters had a mean deviation greater than 10%. The accuracy fluctuated between 0.85 and 0.94. The Kappa index was between 66 to 85. In our clinical trial, the Accu-Chek, Glucotouch, OneTouch, and Precision demonstrated greater accuracy and a higher Kappa index than the HemoCue. CONCLUSIONS: Our data showed good concordance in statistical and clinical parameters for most of the six glucose meters. The HemoCue, recommended as a standard method in several countries, did not show better concordance than most of the tested glucose meters. When used by well-trained personnel, the accuracy of the Accu-Chek, Glucotouch, One-Touch, and Precision was acceptable for use in gestational diabetes screening.     

Effect of thiazolidinedione treatment on progression of subclinical atherosclerosis in premenopausal women at high risk for type 2 diabetes

We tested the effects of treatment with a thiazolidinedione drug on rates of progression of carotid intima-media thickness (CIMT) and some putative determinants of CIMT in young women at high risk for type 2 diabetes. A total of 266 nondiabetic, Hispanic women with recent gestational diabetes were randomized to placebo or troglitazone. CIMT measurements were made at baseline, annually, and at study end, together with measurements of obesity, serum lipids, and glucose and insulin levels during oral glucose tolerance tests. Insulin sensitivity (minimal model analysis) was measured at baseline and 3 months later. Data were analyzed to compare CIMT progression rates between treatment groups and investigate potential determinants of differences in CIMT progression. One hundred ninety-two women had a CIMT measurement at baseline and at least one follow-up visit. The mean rate of CIMT change was 31% lower in women assigned to troglitazone (P = 0.048). This intergroup difference was not explained by baseline or on-trial differences in obesity, lipids, glucose, or insulin. The reduction in CIMT progression developed gradually, occurred only in women who had an increase in insulin sensitivity, and was unrelated to the presence of the metabolic syndrome at baseline. Troglitazone reduced the progression of subclinical atherosclerosis via a mechanism that involved unmeasured mediators of atherosclerosis, either in the circulation or directly in the arterial wall.     

Biogeography and Trypanosoma cruzi infection prevalence of Chagas disease vectors in Texas, USA

Data were pooled from multiple sources including newly collected triatomine specimens, preserved specimens, government reports, and scientific articles to create a biogeographical profile of triatomine vector species found in Texas. Triatomine specimens were documented in 97 of 254 counties, and Trypanosoma cruzi-infected specimens were reported from 48 counties. Triatomine specimens were distributed in 11 of the 12 ecoregions in Texas, with all but one species found in multiple ecoregions. Of the 241 newly collected specimens, 50.74% were infected with T. cruzi. Triatoma gerstaeckeri was the most frequently collected and most geographically dispersed species followed by T. sanguisuga. Three species, T. gerstaeckeri, T. sanguisuga, and T. lecticularia, were associated with human dwellings, and over half of the new specimens found inside or near houses were infected with T. cruzi. Chagas disease vectors in Texas are widely distributed and have adapted to ecologically diverse settings. The high T. cruzi infection prevalence of specimens found in close proximity to human settings suggests the presence of an active peridomestic Chagas disease transmission cycle.