Effects of losartan treatment on cardiac autonomic control during volume loading in patients with DCM

This study evaluated the effect of angiotensin II receptor blockade on cardiac autonomic control adaptation and urine output in response to acute isotonic volume load in patients with idiopathic dilated cardiomyopathy (DCM) and asymptomatic to mildly symptomatic heart failure. Left ventricular volumes and heart rate variability measurements were assessed at baseline and during intravenous saline load in 14 patients before and after 2 mo of losartan treatment. After losartan treatment, blood pressure values were lower, whereas left ventricular ejection fraction was higher (F = 79, P < 0.001), than before treatment. During saline load, ejection fraction decreased before losartan treatment (F = 5.6, P < 0.05) but did not change after treatment. Urinary volume, unchanged during saline load in untreated patients, increased after losartan (F = 9.38, P < 0. 001). Time-domain measurements that represent vagal modulation of heart rate (root-mean-square successive differences and percentage of differences between successive R-R intervals >50 ms) decreased during saline load in untreated patients (F = 3.1, P < 0.05 and F = 6.5, P < 0.01, respectively), but not after losartan. Similarly, a decrease in very low frequency (F = 3.2, P < 0.05), low-frequency (F = 2.9, P < 0.05), and high-frequency power (F = 6.1, P < 0.01) after saline load was observed only in untreated patients. In patients with DCM, losartan treatment improves the cardiac autonomic adaptation and increases urine output in response to volume overload.     

Targeting of calsequestrin to the sarcoplasmic reticulum of skeletal muscle upon deletion of its glycosylation site

The glycoprotein calsequestrin (CS) is segregated to the junctional sarcoplasmic reticulum (jSR) and is responsible for intraluminal Ca(2+) binding. A chimeric CS-hemoagglutinin 1 (HA1), obtained by adding the nine amino acid viral epitope hemoagglutinin to the carboxy terminal of CS and shown to be correctly segregated to skeletal muscle jSR [A. Nori, K. A. Nadalini, A. Martini, R. Rizzuto, A. Villa, and P. Volpe (1997). Chimeric calsequestrin and its targeting to the junctional sarcoplasmic reticulum of skeletal muscle. Am. J. Physiol. 272, C1420-C1428] lends itself as a molecular tool to investigate the targeting domains of CS. A putative targeting mechanism of CS to jSR implies glycosylation-dependent steps in the endoplasmic reticulum (ER) and Golgi complex. To test this hypothesis, CS-HA1DeltaGly, a mutant in which the unique N-glycosylation site Asn316 was changed to Ile, was engineered by site-directed mutagenesis. The mutant cDNA was transiently transfected in either HeLa cells, myoblasts of rat skeletal muscle primary cultures, or regenerating soleus muscle fibers of adult rats. The expression and intracellular localization of CS-HA1DeltaGly was studied by double-labeling epifluorescence by means of antibodies against either CS, HA1, or the ryanodine receptor calcium release channel. CS-HA1DeltaGly was expressed and retained to ER and ER/sarcoplasmic reticulum of HeLa cells and myotubes, respectively, and expressed, sorted, and correctly segregated to jSR of regenerating soleus muscle fibers. Thus, the targeting mechanism of CS in vivo appears not to be affected by glycosylation-that is, the sorting, docking, and segregation of CS are independent of cotranslational and posttranslational glycosylation or glycosylations.     

Tetracycline accumulates in Iberis sempervirens L. through apoplastic transport inducing oxidative stress and growth inhibition

Environmental antibiotic contamination is due mainly to improper and illegal disposal of these molecules that, yet pharmacologically active, are excreted by humans and animals. These compounds contaminate soil, water and plants. Many studies have reported the bioaccumulation of antibiotics in plants and their negative effects on photosynthesis, cell growth and oxidative balance. Therefore, the principal objective of this paper was the study of antibiotic accumulation sites in plants and its uptake modality. Iberis sempervirens L., grown in soil and in agar in the presence or absence of tetracycline, were used as a model system. Using confocal and transmission electron microscopy, we demonstrated that tetracycline was absorbed and propagated in plants through apoplastic transport and also accumulated in intercellular spaces. Tetracycline was rarely detected inside cells (in cytoplasm and mitochondria where, coherent to its pharmacological activity, it probably affected ribosomes), except in stomata. Moreover, we verified and clarified further the phytotoxic effects of tetracycline on plants. We observed that the antibiotic induced a large reduction in plant growth and development and inhibition of photosynthetic activity. As tetracycline may lead to oxidative stress in plants, plant cells tried to balance this disequilibrium by increasing the amount and activity of some endogenous enzyme antioxidant agents (superoxide dismutase 1 and catalase) and levels of antiradical secondary metabolites.     

PULMONARY INFLAMMATORY HYPERINFLATION IN INFANTS

In infants less than 3 years old pulmonary hyperinflation can be a clinical and radiological sign of acute pneumonitis. It is an early, nonspecific occurrence in the presence of inflammation. The most reliable radiologic signs include flattening and undulation of the diaphragm, mediastinal elongation and narrowing, and a cardiac outline completely visualized above the diaphragm.     

Oxidative-induced membrane damage in diabetes lymphocytes: Effects on intracellular Ca2 + homeostasis

Oxidative stress is linked to several human diseases, including diabetes. However, the intracellular signal transduction pathways regulated by reactive oxygen species (ROS) remain to be established. Deleterious effects of ROS stem from interactions with various ion transport proteins such as ion channels and pumps, primarily altering Ca^{2 +} homeostasis and inducing cell dysfunction. This study characterized the Ca^{2 +} transport system in lymphocytes of patients with type-2 diabetes, evaluating the possible correlation between cell modifications and the existence of specific oxidative stress damage. Lymphocytes from type-2 diabetes patients displayed oxidative stress features (accumulation of some ROS species, membrane peroxidation, increase in protein carbonyls, increase in SOD and Catalase activity) and Ca^{2 +} dyshomeostasis (modified voltage-dependent and inositol 1,4,5-triphosphate-mediated Ca^{2 +} channel activities, decrease in Ca^{2 +} pumps activity). The data support a correlation between oxidative damage and alterations in intracellular Ca^{2 +} homeostasis, possibly due to modification of the ionic control in lymphocytes of type-2 diabetes patients.     

SNAP-25 is a promising novel cerebrospinal fluid biomarker for synapse degeneration in Alzheimer’s disease

Background

Synaptic degeneration is an early pathogenic event in Alzheimer’s disease, associated with cognitive impairment and disease progression. Cerebrospinal fluid biomarkers reflecting synaptic integrity would be highly valuable tools to monitor synaptic degeneration directly in patients. We previously showed that synaptic proteins such as synaptotagmin and synaptosomal-associated protein 25 (SNAP-25) could be detected in pooled samples of cerebrospinal fluid, however these assays were not sensitive enough for individual samples.

Results

We report a new strategy to study synaptic pathology by using affinity purification and mass spectrometry to measure the levels of the presynaptic protein SNAP-25 in cerebrospinal fluid. By applying this novel affinity mass spectrometry strategy on three separate cohorts of patients, the value of SNAP-25 as a cerebrospinal fluid biomarker for synaptic integrity in Alzheimer’s disease was assessed for the first time. We found significantly higher levels of cerebrospinal fluid SNAP-25 fragments in Alzheimer’s disease, even in the very early stages, in three separate cohorts. Cerebrospinal fluid SNAP-25 differentiated Alzheimer’s disease from controls with area under the curve of 0.901 (P?<?0.0001).

Conclusions

We developed a sensitive method to analyze SNAP-25 levels in individual CSF samples that to our knowledge was not possible previously. Our results support the notion that synaptic biomarkers may be important tools for early diagnosis, assessment of disease progression, and to monitor drug effects in treatment trials.