Continuous positive airway pressure (CPAP) treatment improves endothelial function and sympathetic activity in patients with obstructive sleep apnea (OSA). However, the long-term effects of CPAP on pulse wave velocity (PWV), which reflects arterial stiffness that is associated with cardiovascular events, have not been evaluated in OSA patients with or without hypertension (HT). In this study, 212 male OSA patients who had been receiving CPAP treatment for 2 years and were divided into two groups, those with HT (n¼114) and those without (n¼98), were studied. In both HT and normotensive (NT) patients, PWV decreased significantly over the first 6 months of treatment (P¼0.005 and 0.010, respectively), before increasing gradually from 6 to 24 months. Body mass index (BMI), body weight, heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) levels decreased significantly in the HT group over the 2 years of CPAP treatment (Po0.001 for all). In contrast, only HR decreased significantly in the NT group over the 2 years of treatment (Po0.001). Multivariate regression analysis revealed that age (P¼0.008), decreases in DBP (Po0.001) and HR (Po0.001) and higher initial levels of serum high-density lipoprotein-cholesterol (P¼0.040) were independent factors related to changes in PWV over the 2 years of CPAP treatment in all patients. In conclusion, we found a significant decrease in PWV in both NT and HT patients after 6 months of CPAP treatment. In HT patients, long-term CPAP treatment significantly decreases blood pressure, which may contribute to explain the PWV improvement.
We have studied the internalization of 125I-erythropoietin (Epo) and regulation of Epo receptors by the ligand in a murine erythroleukemia cell clone, TSA8. To determine internalization, a high-salt acid wash was performed. Internalization of 125I-Epo was found in TSA8 cells as well as in fetal mouse liver cells (FMLC), although the percentage of internalized radioactivity reached 40% after incubation at 37 degrees C for 150 min and was lower than that in FMLC. Exposure of TSA8 cells to unlabeled Epo resulted in a rapid, time-dependent reduction in 125I-Epo binding activity. The net loss of the activity was related to the ambient Epo concentration and 5 X 10(-8)M Epo induced approximately 80% loss of total binding capacity. Scatchard analysis of the binding data revealed that the high-affinity receptor number was decreased but the affinity was increased in the Epo-treated cells. In low-affinity receptors, however, the receptor affinity was decreased and the receptor number was not changed much by preincubation with Epo. These results suggest that the decrease in 125I-Epo binding activity after preincubation with unlabeled Epo is mainly accounted for by a decrease in the number of high-affinity receptors, and the high-affinity receptors play an important role in the biological response to Epo.
Erythropoietin (Epo) titers in various hematological states were determined by a radioimmunoassay. Epo titers in patients with uremic anemia and iron deficiency anemia were inversely correlated with their respective hemoglobin concentrations. Epo titers in patients with uremic anemia were significantly lower than those in patients with iron deficiency anemia with comparable hemoglobin concentrations.
Recombinant plasmids containing DNA complementary to protamine messenger RNA of rainbow trout (Salmo gairdnerii) have been isolated and sequenced. One of the clones contained the entire coding sequence of a protamine gene together with the complete 3' non-coding region. Another clone had an identical nucleotide sequence in the coding region but four base substitutions in the 3' non-coding region. On the basis of a comparison of the nucleotide sequences available at present, the structure and divergence of the protamine gene family are discussed.
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