Early Siberians from Lake Baikal and Alaskan population affinities

Among the materials excavated by the 1975 joint USSR–USA team in Siberia are two burials from Shaman's Cape, Olkhon Island, Lake Baikal. One is a middle-aged male of the Serovo culture, 6,000 B.C. , and the other is a young male of the Glaskovo culture of 2,000 B.C. This later burial displays an unusual pathology affecting the nose and post-cranial regions of the pelvic girdle and lower limbs. Osteon analysis confirms the determination of age at death and illustrates the difference between normal and pathological bone. Numerous cultural materials were associated with these burials, including harpoon heads, knives, a compound fishhook and a pestle with the Serovo man, and nephrite ornaments with the Glaskovo man. The skulls, though far apart in time, are pronouncedly Mongoloid and alike in their low cranial vaults. A low, broad and inclined ascending ramus resembles Chukchi, Eskimos and Aleuts. These two specimens document the Mongoloid character of the early inhabitants of Lake Baikal.     

Russian-American Bering Sea Relations: Research and Reciprocity

Knowledge of the peopling of the New World and of biological and cultural evolution would be enhanced by more US-USSR research exchanges and more joint field expeditions characterized by mutual scientific benefit, specific objectives, and reciprocity, on both sides of the Bering Sea. A brief review of a sample of related events between 1741 and 1981 indicates the continuity of common research problems and productive results that were multiplied by scientific cooperation.     

Effects of exercise training on coronary transport capacity

Coronary transport capacity was estimated in eight sedentary control and eight exercise-trained anesthetized dogs by determining the differences between base line and the highest coronary blood flow and permeability-surface area product (PS) obtained during maximal adenosine vasodilation with coronary perfusion pressure constant. The anterior descending branch of the left coronary artery was cannulated and pump-perfused under constant-pressure conditions (approximately equal to 100 Torr) while aortic, central venous, and coronary perfusion pressures, heart rate, electrocardiogram, and coronary flow were monitored. Myocardial extraction and PS of 51Cr-labeled ethylenediaminetetraacetic acid were determined with the single-injection indicator-diffusion method. The efficacy of the 16 +/- 1 wk exercise training program was shown by significant increases in the succinate dehydrogenase activities of the gastrocnemius, gluteus medialis, and long head of triceps brachii muscles. There were no differences between control and trained dogs for either resting coronary blood flow or PS. During maximal vasodilation with adenosine, the trained dogs had significantly lower perfusion pressures with constant flow and, with constant-pressure vasodilation, greater coronary blood flow and PS. It is concluded that exercise training in dogs induces an increased coronary transport capacity that includes increases in coronary blood flow capacity (26% of control) and capillary diffusion capacity (82% of control).     

Exercise training increases coronary transport reserve in miniature swine

Female yucatan miniature swine were trained on a treadmill (ET) or were cage confined (C) for 16-22 wk. The ET pigs had increased exercise tolerance, heart weight-to-body weight ratio, and skeletal muscle oxidative capacity. After anesthesia the left anterior descending coronary artery was cannulated and pump perfused with blood while aortic, central venous, and coronary perfusion pressures, electrocardiogram, heart rate, and coronary blood flow were monitored. Capillary permeability-surface area product (PS) for EDTA was determined with the single-injection indicator-diffusion method by use of an organ model based on the Sangren-Sheppard equations for capillary transport. Coronary blood flow (CBF) and PS were compared before and during maximal adenosine vasodilation with coronary perfusion pressures at 120 mmHg. Results indicate that there were no differences in base-line CBF or PS between C and ET groups. alpha-Receptor blockade with phentolamine and/or prazosin, before adenosine vasodilation, produced increases in PS in C pigs but had little effect in ET pigs. During maximal vasodilation with adenosine, ET pigs had greater CBF (447 +/- 24 vs. 366 +/- 27 ml.min-1.100 g-1) and greater PS (83 +/- 9 vs. 55 +/- 7 ml.min-1.100 g-1) than the C group. It is concluded that ET induces an increased coronary transport capacity in miniature swine that includes a 22% increase in blood flow capacity and a 51% increase in capillary exchange capacity.     

Exercise training depletes sarcoplasmic reticulum calcium in coronary smooth muscle.

We examined the effects of chronic exercise training on sarcoplasmic reticulum (SR) Ca uptake, spontaneous SR Ca release, and whole-cell currents in coronary smooth muscle cells. Single coronary artery smooth muscle cells demonstrated increases in intracellular free Ca (Cai) during depolarization (measured with fura-2) that were abolished by diltiazem (10(-4) M). Diltiazem significantly inhibited (80%) refilling of the SR Ca store. The SR Ca store of exercise-trained pigs was 64% less after 11 min vs. 2 min of recovery, whereas cells from sedentary pigs showed no depletion. Exercise-training-induced depletion of the SR Ca store was abolished when ryanodine (10(-5) M) was applied during the recovery, but depletion was enhanced by low concentrations of ryanodine (10(-8) M). In smooth muscle from sedentary pigs, 10(-8) M ryanodine mimicked the effects of exercise training by depleting the SR Ca store during 11 min of recovery (54% depletion). When allowed a longer recovery without ryanodine (14 min or without prior depolarization), the SR Ca store in cells from exercise-trained pigs returned toward peak levels. The outward K current vs. voltage relationship did not differ in cells from exercise-trained or sedentary pigs. Exercise training reduced the number of spontaneous transient outward currents normally found in cells from sedentary pigs. We introduce a model that provides a rational basis to explain the results obtained in this study.     

Microvascular injury after ischemia and reperfusion in skeletal muscle of exercise-trained rats

Ischemia and reperfusion in skeletal muscle is associated with increases in total vascular resistance (Rt) and the microvascular permeability to plasma proteins. To determine whether exercise training can attenuate ischemia and reperfusion-induced microvascular injury in skeletal muscle, intact (with skin) and skinned, maximally vasodilated (papaverine), isolated hindquarters of control (C) and exercise-trained (ET) rats were subjected to ischemia (intact 120 min; skinned 60 min) followed by 60 min of reperfusion. ET rats ran on a motorized treadmill at 32 m/min (8% grade), 2 h/day for 12 wk, whereas the C rats were cage confined. Before ischemia, ET hindquarters had higher isogravimetric flow, lower Rt, and similar solvent drag reflection coefficients (sigma f) compared with C. During reperfusion in intact hindquarters, flow was higher (P less than 0.05) and Rt tended to be lower (15 +/- 2 vs. 25 +/- 5 mmHg.ml-1.min.100 g; P less than 0.1) in ET compared with C; however, in skinned hindquarters flow and Rt (14 +/- 2 vs. 13 +/- 2 mmHg.ml-1.min.100 g) were not different between C and ET. During reperfusion, sigma f was reduced (P less than 0.05) in both intact (C 0.68 +/- 0.03; ET 0.68 +/- 0.02) and skinned (C 0.66 +/- 0.03; ET 0.68 +/- 0.03) hindquarters, indicative of an increased microvascular permeability to plasma proteins. These results indicate that exercise training did not attenuate the microvascular injury (increased Rt and decreased sigma f) associated with ischemia and reperfusion in rat skeletal muscle.     

Fractionation of the gene-size macronuclear chromatin fragments of the binucleated eukaryote Oxytricha

Summary The macronuclear chromatin of Oxytrichia nova consists of chromatin fragments which are fully soluble in 0.2 mM EDTA and whose DNA length varies from 500–25 000 bp. The DNA migrates electrophoretically as a series of discrete bands, with specific genes present in only one or a few bands. The chromatin fragments are composed of nucleosomes and migrate electrophoretically in proportion to their DNA length. These results suggest schemes for the fractionation of undigested chromatin in order to enrich for specific genes, facilitating analysis of changes in chromatin structure associated with changes in gene expression.     

Effect of exercise training on intracellular free Ca2+ transients in ventricular myocytes of rats.

The purpose of this study was to test the hypothesis that exercise training induces enhanced intracellular free Ca2+ (Cai) availability to the contractile elements of cardiac cells. Cai transients were directly measured in single isolated contracting ventricular myocytes from exercise-trained (EX) and sedentary control (SED) rats. Male Sprague-Dawley rats underwent 16 wk of progressive treadmill exercise (32 m/min, 8% grade, 1.5 h/day) (EX) or were cage confined (SED). EX rats had lower resting heart rate and elevated skeletal muscle oxidative capacity. Cai was measured with the fluorescent Cai indicator fura-2. Simultaneous video monitoring indicated that myocytes suspended in physiological salt solution were quiescent until stimulated electrically at a frequency of 0.2 Hz (12-36 V, 2-ms duration). Stimulated Cai transients, measured from changes in fura-2 fluorescence, were similar in cells from EX and SED groups. Peak shortening, time to peak shortening, velocity of shortening, contraction duration, and time to half-relaxation were also similar in cells from EX and SED rats. Ryanodine (10 microM) was applied to eliminate the contribution of Ca2+ release from sarcoplasmic reticulum to the Cai transient. Verapamil was applied to eliminate the contribution of voltage-gated Ca2+ channels to Cai transients. Cai transients were also similar in cells from EX and SED groups after these pharmacological interventions. These results suggest that treadmill training of rats does not alter Cai availability to the contractile elements in isolated ventricular myocytes.