Life Lines by Dr. Dolittle

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Tag Archive for ‘American Journal of Physiology’

Growth restriction in utero increases risk for developing insulin resistance

  A new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, explored how restricted growth of a fetus during pregnancy can lead to insulin resistance later in life. They studied this risk factor in guinea pigs as larger litter sizes are known to restrict the growth of developing fetuses. Findings from the study showed that neonatal guinea pigs grow rapidly after birth to compensate for […]

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Lactate directly increases breathing

Hypoxic environments increase ventilation in animals. This helps to bring in more oxygen when environmental levels may be limited. With limited oxygen availability, the body turns to anaerobic metabolism, resulting in the production of lactate ions. These ions are known to indirectly stimulate breathing by lowering blood pH and were more recently discovered to directly stimulate the carotid body to increase breathing. For this reason, lactate ions are thought to […]

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PUFAs change muscle characteristics in a migratory bird without improving flight performance

Migratory birds are undoubtedly endurance athletes. In fact, their flights last hours to days. Could you imagine? But, unlike mammals that fuel endurance exercise by burning carbohydrates, birds fuel their endurance flights with fat. In a new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, researchers were curious about whether the TYPE of dietary fat used to fuel endurance exercise was important. To examine this […]

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Historical perspectives on homeostasis

In a new article published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, Dr. David S. Goldstein (National Institutes of Health) presents an elegant historical perspective on homeostasis. Walter B. Cannon (1871-1945) was a physiologist at Harvard Medical School who is credited with coining the term “homeostasis” to describe how the body attempts to regulate itself to stay healthy. The ability for the body to regulate the […]

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Carnivorous fish are glucose intolerant

Who would have thought that carnivorous fish, like the gilthead sea bream pictured above, and people with diabetes have a lot in common? These fish are glucose intolerant, meaning they are not able to use glucose for energy very well. When these fish are given carbohydrates, their blood sugar increases as does their ability to produce fats through lipogenesis. The purpose of this increase may be to store the excess […]

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Could zinc be involved in forming kidney stones?

Zinc is a micronutrient that is essential for normal protein production and for various enzymes to function properly in the body. Levels are important to regulate because too much can be toxic to the kidneys whereas too little can lead to problems with immune and metabolic function as well as infertility. In a new study published in American Journal of Physiology – Renal Physiology, researchers were interested in how zinc […]

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Importance and dangers of oxygen for air-breathing animals

Although oxygen is essential for air-breathing species and allowed for the evolution of multicellular organisms, it is also a dangerous molecule that can lead to cellular toxicity through the generation of reactive oxygen species (ROS). However, it is important to point out that cellular ROS also play several physiological roles in the body. I just read an interesting review article published in Physiological Reviews that explored natural oxygen delivery and availability […]

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Porcine adaptation to heat stress

  A new study published in American Journal of Physiology – Regulatory, Integrative and Comparative Physiology explored the effects of modest heat stress (35°C, 95°F) on the physiology of pigs. The found that pigs exposed to heat stress ate less than those exposed to ambient temperatures. I understand. I eat less when it is hot outside too. Since skeletal muscle is such a large metabolically active tissue, things that alter muscle metabolism […]

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How sheep are helping human pregnancies

    The growth and development of a human fetus is difficult to study, both practically and ethically, as I am sure you can imagine. A new review article published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology explored how sheep have helped solve this problem as fetal sheep share similar brain, lung and cardiac development and placental physiology with humans, many aspects of which differ from […]

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Compromising fish

Here’s something to think about. How do fish optimize gas exchange in their gills to efficiently take up oxygen (favoring large, thin, permeable membranes) while at the same time limiting water and ion movement across the surface? If they reduce surface area, then oxygen transfer will be limited, but ions and water transfer will be optimized. What is a fish to do? A new review article published in Physiology discussed how […]

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