Culture-independent species typing of neotropical Leishmania for clinical validation of a PCR-based assay targeting heat shock protein 70 genes

PCR-restriction fragment length polymorphism analysis of heat shock protein 70 genes discriminates most neotropical Leishmania species, as well as Trypanosoma cruzi. The assay, combined with capillary electrophoresis in a microchip device, may be applied directly on clinical samples with a high sensitivity, hence supporting clinical and epidemiological monitoring of leishmaniasis.     

Impact of suppression of viral replication by highly active antiretroviral therapy on immune function and phenotype in chronic HIV-1 infection

We compared immune phenotypes, lymphocyte proliferation (LP), and delayed type hypersensitivity (DTH) responses in 28 male antiretroviral treatment-naive and experienced HIV-1-infected patients, matched pair-wise according to age and CD4+ T-lymphocyte count. Median CD4+ T-lymphocyte counts were 441 cells/microL and 483 cells/microL and median CD4+ T-lymphocyte nadirs were 435 cells/microL and 150 cells/microL in both groups, respectively. Absolute numbers of circulating T-lymphocyte subpopulations and proportions of naive and memory T-lymphocytes were comparable in the two groups. Untreated patients had greater proportions of activated CD4+ (p <.05) and CD8+ (p <.01) T-cells expressing human leukocyte antigen (HLA)DR and CD38 and fewer CD8+ cells expressing CD28 (p <.05). DTH and LP responses were comparable in both groups except for HIVp24, LP responses, and mumps DTH responses, which were of greater magnitude in the group treated with highly active antiretroviral therapy (HAART) (p <.05). Thus, HIV-1-infected patients who experienced substantial increases in CD4+ T-lymphocyte counts after suppression of viral replication on HAART had fewer activated lymphocytes and similar immune function when compared with findings in untreated patients with similar CD4+ T-cell counts. HIV replication has minimal real-time effect on CD4+ T-cell function in response to non-HIV antigens but helper T-cell responses to HIV-gag antigen are impaired during ongoing viral replication and may be restored by antiretroviral therapy.     

Superiority of magnesium cardioplegia in neonatal myocardial protection

Background. We have shown that magnesium can offset the detrimental effects of normocalcemic cardioplegia in hypoxic neonatal hearts. It is not known, however, whether magnesium offers any additional benefit when used in conjunction with hypocalcemic cardioplegia.

Methods. Twenty neonatal piglets underwent 60 minutes of ventilator hypoxia (FiO₂ 8% to 10%) followed by 20 minutes of normothermic ischemia on cardiopulmonary bypass (hypoxic-ischemic stress). They then underwent 70 minutes of multidose blood cardioplegic arrest. Five (Group 1), received a hypocalcemic (Ca⁺² 0.2 to 0.4 mM/L) cardiologic solution without magnesium, whereas in 10, magnesium was added at either a low dose (5 to 6 mEq/L, Group 2) or high dose (10 to 12 mEq/L, Group 3). In the last 5 (Group 4), magnesium (10 to 12 mEq/L) was added to a normocalcemic cardioplegic solution. Function was assessed using pressure volume loops and expressed as percentage of control.

Results. Compared to hypocalcemia cardioplegic solution without magnesium (Group 1), both high- and low-dose magnesium enrichment (Groups 2 and 3) improved myocardial protection resulting in complete return of systolic (40% vs 101% vs 102%) (p < 0.001 vs Groups 2 and 3) and global myocardial function (39% vs 102% vs 101%) (p < 0.001 vs Groups 2 and 3), and reduced diastolic stiffness (267% vs 158% vs 154%) (p < 0.001 vs Groups 2 and 3). Conversely, even high-dose magnesium supplementation could not offset the detrimental effects of normocalcemic cardioplegia resulting in depressed systolic (End Systolic Elastance [EES] 41% ± 1%) (p < 0.001 vs Groups 2 and 3) and global myocardial function (40% ± 1%) (p < 0.001 vs Groups 2 and 3), and a marked rise in diastolic stiffness (258% ± 5%) (p < 0.001 vs Groups 2 and 3). Hypocalcemic magnesium cardioplegia has now been used successfully in 247 adult and pediatric patients.

Conclusions. Magnesium enrichment of hypocalcemic cardioplegic solutions improves myocardial protection resulting in complete functional preservation. However, magnesium cannot prevent the detrimental effects of normocalcemic cardioplegia when the heart is severely stressed. This study, therefore, strongly supports using both a hypocalcemic cardioplegic solution and magnesium supplementation as their benefits are additive.     

Pathophysiology of cardiac extracorporeal membrane oxygenation

The treatment of cardiogenic shock using inotropic agents and vascular volume expansion places an added burden on the heart. The resultant increase in cardiac work may cause myocardial ischemia and lead to cardiac arrest. Extracorporeal membrane oxygenation (ECMO) may be used to treat cardiogenic shock. It supports systemic circulation, assures diastolic perfusion of the myocardium, and reduces cardiac workload. The rise in blood pressure associated with restoring systemic circulation afterloads the heart and can cause left atrial hypertension and pulmonary edema. ECMO does not automatically reduce cardiac work, especially in the presence of residual shunts. Left atrial drainage or decompression may be essential in certain patients both to avert pulmonary edema and to reduce cardiac work.     

qMRI relaxometry of mandibular bone marrow: A monomodal distribution in sickle cell disease

Purpose:

To identify and characterize sickle cell disease (SCD)‐related changes in the composition of mandibular bone marrow using qMRI relaxometry histograms.

Materials and Methods:

Thirteen SCD patients and 17 controls underwent brain MR imaging with the mixed turbo spin‐echo (TSE) pulse sequence at 1.5T. The mandible was manually segmented and divided into body, angle, ramus, and condyle. T1 and T2 histograms of each mandible were modeled with Gaussian functions. The relaxation time histogram peaks were calculated, and the number of monomodal versus bimodal curves was compared.

Results:

SCD patients exhibited monomodal distributions on both T1 and T2 histograms, consistent with a composition of predominantly red hematopoietic marrow. Eighty‐eight percent of mandibles in control subjects exhibited a bimodal distribution in T1 and all showed a bimodal distribution in T2, indicating mixed but predominantly yellow marrow composition. The second peak in control subjects was shorter in T1 and longer in T2, consistent with yellow marrow composition.

Conclusion:

Instead of physiological fatty replacement, SCD patients exhibit red marrow persistence in the mandible, likely due to the increased demand for hematopoiesis. This phenomenon can be manifested by a monomodal curve in both T1 and T2 relaxometric histograms. J. Magn. Reson. Imaging 2013;37:1182–1188. © 2012 Wiley Periodicals, Inc.     

Multiexponential T2 analyses in a murine model of hepatic fibrosis at 11.7 T MRI

This study evaluated the effects of hepatic fibrosis on the multiexponential T₂ (MET₂) relaxation of ex vivo murine liver specimens using an 11.7 T MRI. This animal study was approved by the Institutional Animal Care and Use Committee. Eighteen male C57BL/6 mice were divided into control (n = 3) and experimental (n = 15) groups; the latter group was fed a 3,5‐dicarbethoxy‐1,4‐dihydrocollidine‐supplemented diet to induce hepatic fibrosis. Ex vivo liver specimens were imaged using an 11.7 T MRI scanner. A multi‐echo spin‐echo sequence was utilized for subsequent MET₂ analysis. Degrees of fibrosis were determined by a pathologist, as well as by digital image analysis. Scatterplot graphs comparing various features of the MET₂ signal decay with the degrees of fibrosis were generated, and correlation coefficients were calculated. Two distinct peaks of the MET₂ signal decay were identified in all liver specimens: a short T₂ component with a geometric mean T₂ (GMT₂) approximating 30 ms; and a long T₂ component with GMT₂ approximating 400 ms. Strong correlation was found between the degree of hepatic fibrosis and the amplitude of the short T₂ component, with a higher degrees of fibrosis associated with a lower amplitude. Moderate correlation was also found between hepatic fibrosis and the GMT₂ values of the long T₂ component, with higher degrees of fibrosis associated with lower GMT₂ values. The study of hepatic microenvironments using MET₂ analyses offers potential utility in the ongoing development of the noninvasive assessment of hepatic fibrosis using MRI. Copyright © 2012 John Wiley & Sons, Ltd.     

Thalamic diffusion differences related to cognitive function in white matter lesions

Cerebral white matter lesions (WMLs) are related to cognitive deficits, probably due to a disruption of frontal–subcortical circuits. We explored thalamic diffusion differences related to white matter lesions (WMLs) and their association with cognitive function in middle-aged individuals. Ninety-six participants from the Barcelona-AsIA Neuropsychology Study were included. Participants were classified into groups based on low grade and high grade of periventricular hyperintensities (PVHs) and deep white matter hyperintensities (DWMHs). Tract-Based Spatial Statistics was used to study thalamic diffusion differences between groups. Mean fractional anisotropy (FA) values in significant areas were calculated for each subject and correlated with cognitive performance. Participants with high-grade PVHs and DWMHs showed lower FA thalamic values compared to those with low-grade PVHs and DWMHs, respectively. Decreased FA thalamic values in high-grade DWMHs, but not high-grade PVH, were related to lower levels of performance in psychomotor speed, verbal fluency, and visuospatial skills. Thalamic diffusion differences are related to lower cognitive function only in participants with high-grade DWMHs. These results support the hypothesis that fronto–subcortical disruption is associated with cognitive function only in DWMHs.