Chronic hypoxia (CH) increases pulmonary endothelial nitric oxide synthase (eNOS) protein levels in adult rats but decreases eNOS protein levels in neonatal pigs. We hypothesized that this differing response to CH is due to developmental rather than species differences. Adult and neonatal rats were placed in either hypobaric hypoxia or normoxia for 2 wk. At that time, body weight, hematocrit, p...

In this study we tested the hypothesis that long-term neuropathological outcome is worsened by hyperoxic compared to normoxic reperfusion in a rat global cerebral ischemia model. Adult male rats were anesthetized and subjected to bilateral carotid arterial occlusion plus bleeding hypotension for 10 min. The rats were randomized to one of four protocols: ischemia/normoxia (21% oxygen for 1 h), i...

The goal of this study was to determine whether hypoxia alters expression of endothelial nitric oxide synthase (eNOS) in the systemic circulation. Rats breathed either air or 10% oxygen for 12 hours, 48 hours, or 7 days. Thoracic aortas were excised and either mounted in organ bath myographs or frozen in liquid nitrogen for later extraction of protein and RNA. eNOS protein (Western blotting) wa...

MicroRNAs (miRNA) are endogenously expressed noncoding RNAs with important biological and pathological functions that are yet to be fully defined. This study investigated alterations in miRNA expression in head and neck squamous cell carcinoma (HNSCC), the incidence of which is rising throughout the world. Initial screening and subsequent analysis identified a panel of aberrantly expressed miRN...

RATIONALE There is evidence that impairments in nitric oxide (NO) signaling contribute to chronic hypoxia-induced pulmonary hypertension. The L-arginine-NO precursor, L-citrulline, has been shown to ameliorate pulmonary hypertension. Sodium-coupled neutral amino acid transporters (SNATs) are involved in the transport of L-citrulline into pulmonary arterial endothelial cells (PAECs). The functio...

background: radiation-sensitive polymer gels are among the most promising three-dimensional dose verification tools and tissue-like developed to date. among the special features of this type of dosimeters, is be doped with other elements or chemicals which made them appropriate for investigating of dose enhancement with contrast agents, by high atomic number. material and methods: in this study...

Time-dependent ventilatory responses to episodic and continuous isocapnic hypoxia were measured in unidirectionally ventilated, awake ducks. Three protocols were used: (1) ten 3-min episodes of moderate hypoxia (10% O(2)) with 5-min normoxic intervals; (2) three 3-min episodes of severe hypoxia (8% O(2)) with 5-min normoxic intervals; and (3) 30-min of continuous moderate hypoxia. Ventilation (...

Mammalian cells respond to changes in oxygen availability through a conserved pathway that is regulated by the hypoxia-inducible factor (HIF). The alpha subunit of HIF is targeted for degradation under normoxic conditions by a ubiquitin-ligase complex that recognizes a hydroxylated proline residue in HIF. We identified a conserved family of HIF prolyl hydoxylase (HPH) enzymes that appear to be ...

Optimization of oxygen tolerance extension by intermittent exposure was studied in groups of 20 rats exposed to systematically varied patterns of alternating oxygen and normoxic breathing periods at 4.0, 2.0, and 1.5 ATA. Oxygen periods of 20, 60, and 120 min were alternated with normoxic intervals that provided oxygen-to-normoxia ratios of 4:1, 2:1, 1:1, and 1:3. In general, median survival ti...

In the vertebrate lens, nuclei and other cytoplasmic organelles are degraded in fiber cells situated in the center of the tissue. This is believed to ensure the transparency of the tissue. The mechanism that triggers this process is unknown. We hypothesized that standing gradients of oxygen generated within the tissue may serve as a spatial cue for organelle degradation. To examine this possibi...