Breath-hold duration in man and the diving response induced by face immersion

The objective of this study in 5 selected volunteer subjects was to see whether the circulatory diving response which is elicited by breath holding and by cold water on the face would affect the duration of maximal-effort breath holds. Compared to control measurements (breath holding during resting, breathing with 35 degrees C water on the face) breath holding with the face cooled by 20 degrees C water caused a 12% reduction of heart rate, 6% reduction of cardiac output, 33% reduction in [corrected] forearm blood flow, and 9% rise in mean arterial blood pressure, but there was no difference in breath-hold duration (control and experimental both 94 s). There were also no differences in time of appearance of the first involuntary respiratory efforts during breath holding, in alveolar gas exchange, or in breaking-point alveolar O2 and CO2 tensions. When the diving response was magnified by a brief bout of exercise so that there was a 19% [corrected] reduction in heart rate, 23% reduction in cardiac output, and 48% reduction in forearm blood flow, breath-hold duration was still unaffected by face cooling. Compared to intermittent immersions, continuous exposure of the face to cold water abolished the diving response, probably by a cold adaptation of facial thermal receptors. These results with cooling of the face only are consistent with our earlier finding that there was a negative correlation between the duration of a maximal-effort breath hold and the diving response during whole-body submersion in cold water.     

"Chemical fingerprints" of pumice from Cappadocia (Turkey) and Kos (Greece) for archaeological applications.

Pumice has been used as a serviceable abrasive or religious artefact since antiquity and has therefore been an object of trade. It can be found in excavations of ancient workshops all over the Mediterranean.Pumice lumps from the major pumice-bearing rhyolitic tephra units in Cappadocia—the Central Anatolian Volcanic Province, Turkey (in particular the ignimbrites Kavak, Çemilköy, Tahar, Gördeles, and the volcanic complexes of Acıgöl and Hasan Dağı), were sampled and analyzed for major and trace element concentrations using instrumental neutron activation analysis (INAA). Elements determined were Na, K, Sc, Cr, Fe, Co, Zn, As, Rb, Zr, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Th, and U.Since the distribution of those elements is characteristic of the products of a certain eruption, this “chemical fingerprint” can be used to establish the origin of an unknown pumice sample by comparison with samples of known origin. In the course of this study, it could be shown that one pumice finding from the excavation in Miletos (Turkey) probably originates from the Hasan Dağı volcanic complex in Cappadocia. Since it is known that the population in Miletos focused their trade connections on the Mediterranean, this result is somewhat surprising.Two other samples from Miletos show a very high similarity to the chemical fingerprint of pumice from the Kos Plateau Tuff (KPT; Greece): In one case, the identification is doubtless, in the other case identification as KPT seems quite probable.     

Isolated noncompaction of the ventricular myocardium

Isolated noncompaction of the ventricular myocardium is a recently described anomaly. We report the first case of this anomaly presenting as a restrictive cardiomyopathy, and the first association of this entity with endocardial fibrosis.