Mechanisms of glucose intolerance in cystic fibrosis

AIMS

Although cystic fibrosis-related diabetes (CFRD), a poor prognostic factor in cystic fibrosis (CF), is characterized by insulinopenia, the role of insulin resistance is unclear. Using a prospective study design, we measured insulin resistance, pancreatic beta-cell function and correlated glycaemic status with clinical parameters.

METHODS

Oral glucose tolerance test was performed in 60 stable adult CF patients. Insulin sensitivity and beta-cell function were measured using the homeostatic model assessment (HOMA2), Stumvoll and oral glucose insulin sensitivity (OGIS) indices.

RESULTS

Forty-two (70%) had normal glucose tolerance (NGT), 10 (17%) impaired glucose tolerance (IGT) and eight (13%) CFRD. There was no difference in insulin sensitivity among the three groups (HOMA2: NGT 280, IGT 250, CFRD 339, P = 0.42; Stumvoll: NGT 0.128, IGT 0.126, CFRD 0.129, P = 0.76; and OGIS: NGT 515, IGT 472, CFRD 472, P = 0.12). Pancreatic beta-cell function (CFRD 50% vs. NGT 67%; P < 0.05) and first-phase insulin secretion were reduced in CFRD (250 vs. NGT 509; P = 0.004). First-phase insulin secretion was inversely correlated with 1-h (r = -0.74; P < 0.0001) and 2-h glucose levels (r = -0.34; P < 0.05). There was no difference in body mass index or poor lung function (forced expiratory volume in 1 s: CFRD 54% vs. NGT 65%; P = 0.43). However, there were more hospital admissions in the CFRD group (three vs. NGT one per patient per year; P < 0.05).

CONCLUSIONS

CFRD is characterized by qualitative and quantitative defects in insulin secretion, but not insulin resistance, and is associated with increased hospital admissions for pulmonary exacerbations.

Urinary tract infection after stroke

BACKGROUND

Urinary tract infection (UTI) is a recognized complication of stroke. We aimed to determine the incidence of UTI after acute stroke, the risk factors associated with this complication, and its association with outcome.

METHODS

Prospective study of consecutive acute stroke patients admitted to an urban teaching hospital. Routine clinical assessment included the modified National Institutes of Health Stroke Scale (mNIHSS) and modified Rankin scale (mRS). Patients were followed up for 3 months, including recording of clinician diagnosis of UTI.

RESULTS

We studied 412 patients; 65 (15.8%) were diagnosed with UTI, at a median of 14 days (IQR = 4-39) post-stroke. In a binomial multivariate regression analysis, UTI was associated with urinary catheterization (OR = 3.03, 95% CI 1.41-6.52), higher mRS (OR = 1.85, 1.29-2.64) and increasing age (OR = 1.51, 1.13-2.00 for each decade). UTI was associated with death or disability at 3 months, however, this link was attenuated and became non-significant when measures of stroke severity and pre-stroke morbidity were included in a multivariate analysis.

CONCLUSION

UTI is common after acute stroke. It is associated with urinary catheterization, post-stroke disability and increasing age. Avoidance of catheterization might reduce the incidence of this common complication.

Serum amyloid type A may be a predictor of restenosis

BACKGROUND

Elevation of acute phase proteins [C-reactive protein (CRP) and serum amyloid type A (SAA)] has been demonstrated in unstable angina with an adverse clinical prognosis.

HYPOTHESIS

The study was undertaken to determine the effect of angioplasty on the levels of SAA and the correlation with postangioplasty restenosis.

METHODS

In a university-affiliated tertiary medical center, a prospective case study was undertaken in 55 patients who underwent successful percutaneous transluminal coronary angioplasty (PTCA) of a single coronary lesion for angina pectoris. Three groups of patients were clinically characterized according to Braunwald's classification of anginal syndrome: Group A: class III; Group B: class I; Group C: stable angina. Serum amyloid type A was measured by an ELISA method before PTCA and after 24 h, 1, and 3 months. Patients were followed clinically for 12 months. A thallium stress perfusion scan was performed 3 months after PTCA and coronary angiography was repeated in patients with an abnormal thallium perfusion scan.

RESULTS

Serum amyloid type A levels > 100 micrograms/ml could identify Group A patients with a high sensitivity and specificity (r = 0.85 and 0.86, respectively). Of the patients studied, 75% increased their SAA level 24 h after angioplasty. An increase of SAA by > 100% was associated with an increased risk of restenosis, with a relative risk of 6.4 (p < 0.05).

CONCLUSION

Increased levels of SAA characterize patients with unstable angina pectoris with a high specificity and sensitivity. Levels of SAA that increase > 100% 24 h after angioplasty may serve as a marker of restenosis.