scholarly journals Tibetans Retained Innate Ability Resistance to Acute Hypoxia after Long Period of Residing at Sea Level

2008 ◽  
Vol 58 (3) ◽  
pp. 167-172 ◽  
Author(s):  
Zhao-Nian Zhou ◽  
Jian-Guo Zhuang ◽  
Xiu-Feng Wu ◽  
Yi Zhang ◽  
Pipat Cherdrungsi
2021 ◽  
Author(s):  
Marija Pervan ◽  
Jadranka Šepić

<p>The Adriatic Sea is known to be under a high flooding risk due to both storm surges and meteorological tsunamis, with the latter defined as short-period sea-level oscillations alike to tsunamis but generated by atmospheric processes. In June 2017, a tide-gauge station with a 1-min sampling resolution has been installed at Stari Grad (middle Adriatic Sea), the well-known meteotsunami hot-spot, which is, also, often hit by storm surges. </p><p>Three years of corresponding sea-level measurements were analyzed, and 10 strongest episodes of each of the following extreme types were extracted from the residual series: (1) positive long-period (T > 210 min) extremes; (2) negative long-period (T > 210 min) extremes; (3) short-period (T < 210) extremes. Long-period extremes were defined as situations during which sea level surpasses (is lower than) 99.7 (i.e. 2) percentile of sea level height, and short-period extremes as situations during which variance of short-period sea-level oscillations is higher than 99.4 percentile of total variance[J1]  of short-period series. A strong seasonal signal was detected for all extremes, with most of the positive long-period extremes appearing during November to February, and most of the negative long-period extremes during January to February. As for the short-period extremes, these appear evenly throughout the year, but strongest events seem to appear during May to July.</p><p>All events were associated to characteristic atmospheric situations, using both local measurements of the atmospheric variables, and ERA5 Reanalysis dataset. It was shown that positive low-pass extremes commonly appear during presence of low pressure over the Adriatic associated with strong SE winds (“sirocco”), and negative low-pass extremes are associated to the high atmospheric pressure over the area associated with either strong NE winds (“bora”), or no winds at all. On the other hand, high-pass sea level extremes are noticed during two distinct types of atmospheric situations corresponding to both “bad” (low pressure, strong SE wind) and “nice” (high pressure, no wind) weather.</p><p>It is particularly interesting that short-period extremes, of which strongest are meteotsunamis, are occasionally coincident with positive long-period extremes contributing with up to 50 percent to total sea level height – thus implying existence of a double danger phenomena (meteotsunami + storm surge). </p>


NeuroImage ◽  
2005 ◽  
Vol 28 (4) ◽  
pp. 947-955 ◽  
Author(s):  
Egill Rostrup ◽  
Henrik B.W. Larsson ◽  
Alfred P. Born ◽  
Gitte M. Knudsen ◽  
Olaf B. Paulson
Keyword(s):  

1975 ◽  
Vol 229 (2) ◽  
pp. 270-274 ◽  
Author(s):  
GA Beller ◽  
SR Giamber ◽  
SB Saltz ◽  
TW Smith

The arrhythmogenic and respiratory effects of ouabain during chronic hypoxia were studied in 10 unanesthetized dogs in a hypobaric chamber (446 mmHg) following 7-19 (mean 14.7) days of continuous exposure at this altitude. Another 15 dogs studied at sea level comprised the normoxic control group. In both groups, a 7.5-mug/kg loading dose of ouabain was followed by infusion of ouabain at 3.0 mug/kg per min to ECG evidence of toxicity. Mean arterial Po2 was 46 +/- 5 mmHg in chronically hypoxic dogs as compared to 86 +/- 7 mmHg in normoxic animals (P less than 0.001). Mean hematocrit was 54 +/- 1% in hypoxic and 43 +/- 2% in normoxic groups (P less than 0.001). In five dogs studied first at sea level and subsequently under conditions of chronic hypoxia, mean maximum left ventricular dP/dt and peak (dP/dt)P-1 were unchanged. Marked hyperventilation during ouabain infusion was observed. In normoxic dogs mean arterial pH rose from 7.43 +/- 0.05 to 7.70 +/- 0.02 U, and Pco2 fell from 41 +/- 4 to 15 +/- 1 mmHg during ouabain administration (P less than 0.001). Similar changes were observed in hypoxic dogs. There was no significant difference in the mean toxic dose of ouabain in chronically hypoxic (71 +/- 11 mug/kg) versus normoxic (78 +/- 12 mug/kg) animals. Thus, in contrast to acute hypoxia, chronic hypoxia in unanesthetized dogs was not associated with a significant reduction in the dose of ouabain required to produce toxic arrhythmias. Chronic hypoxia was also not associated with alterations in left ventricular performance.


1988 ◽  
Vol 65 (6) ◽  
pp. 2632-2640 ◽  
Author(s):  
R. F. Grover ◽  
R. L. Johnson ◽  
R. G. McCullough ◽  
R. E. McCullough ◽  
S. E. Hofmeister ◽  
...  

It is unclear whether dogs develop pulmonary hypertension (PH) at high altitude. Beagles from sea level were exposed to an altitude of 3,100 m (PB 525 Torr) for 12-19 mo and compared with age-matched controls remaining at low altitude of 130 m (PB 750 Torr). In beagles taken to high altitude as adults, pulmonary arterial pressures (PAP) at 3,100 m were 21.6 +/- 2.6 vs. 13.2 +/- 1.2 Torr in controls. Likewise, in beagles taken to 3,100 m as puppies 2.5 mo old, PAP was 23.2 +/- 2.1 vs. 13.8 +/- 0.4 Torr in controls. This PH reflected a doubling of pulmonary vascular resistance and showed no progression with time at altitude. Pulmonary vascular reactivity to acute hypoxia was also enhanced at 3,100 m. Inhibition of prostaglandin synthesis did not attenuate the PH or the enhanced reactivity. Once established, the PH was only partially reversed by acute relief of chronic hypoxia, but reversal was virtually complete after return to low altitude. Hence, beagles do develop PH at 3,100 m of a severity comparable to that observed in humans at the same or even higher altitudes.


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