Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Tension01:10

Tension

13.7K
Tension is a force along the length of a medium, in particular, a force carried by a flexible medium, such as a rope or cable. The word "tension" comes from Latin, meaning "to stretch". Not coincidentally, the flexible cords that carry muscle forces to other parts of the body are called tendons. Any flexible connector, such as a string, rope, chain, wire, or cable, can exert pull only parallel to its length; so, a force carried by a flexible connector is a tension with a...
13.7K
Surface Tension, Capillary Action, and Viscosity02:57

Surface Tension, Capillary Action, and Viscosity

33.1K
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
33.1K
Surface Tension of Fluid01:22

Surface Tension of Fluid

1.5K
Surface tension is a fundamental property of fluids, occurring at the boundary between a liquid and a gas or between two immiscible liquids. This phenomenon arises from the cohesive forces between molecules at the fluid's surface, creating an effect similar to a stretched elastic membrane. Inside each fluid, molecules are equally attracted in all directions by neighboring molecules, but surface molecules experience a net inward force, resulting in surface tension.
Surface tension varies...
1.5K
Aging01:26

Aging

659
Aging is a complex biological phenomenon influenced by various processes that affect cellular and systemic functions. Several prominent theories attempt to explain its mechanisms, highlighting cellular limitations, oxidative damage, and hormonal changes as central factors in aging.
Cellular Clock Theory
The cellular clock theory posits that the human lifespan is closely tied to the finite capacity of cells to divide, a phenomenon governed by telomeres, which are protective caps at the ends of...
659
Frequency-dependent Selection01:21

Frequency-dependent Selection

23.4K
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.
23.4K
Temperature Dependence on Reaction Rate02:55

Temperature Dependence on Reaction Rate

88.7K
The Collision Theory
Atoms, molecules, or ions must collide before they can react with each other. Atoms must be close together to form chemical bonds. This premise is the basis for a theory that explains many observations regarding chemical kinetics, including factors affecting reaction rates.
The collision theory is based on the postulates that (i) the reaction rate is proportional to the rate of reactant collisions, (ii) the reacting species collide in an orientation allowing contact between...
88.7K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Natural History of C3 Glomerulopathy and Immune Complex-Associated Membranoproliferative Glomerulonephritis in Children.

Clinical journal of the American Society of Nephrology : CJASN·2026
Same author

Contemporary Treatment Responses of Recurrent Focal Segmental Glomerulosclerosis or Steroid Resistant Nephrotic Syndrome in Children after Kidney Transplantation: Phase 2 of a Multicenter Electronic Health Record Data Analysis.

Research square·2026
Same author

Comparative Effectiveness of Antihypertensive Medications in Children With Chronic Kidney Disease.

JAMA pediatrics·2026
Same author

Optical photothermal infrared spectroscopic assessment of microplastics in tissue models and non-digested human tissue sections.

The Analyst·2026
Same author

CORR Insights®: Is RAGE Expression in Flexor Tendon Synovium Associated With Carpal Tunnel Syndrome in Patients With Diabetes?

Clinical orthopaedics and related research·2026
Same author

Trends in US Children's Mortality, Chronic Conditions, Obesity, Functional Status, and Symptoms.

JAMA·2025

Related Experiment Video

Updated: Jan 26, 2026

Cerebral Blood Oxygenation Measurement Based on Oxygen-dependent Quenching of Phosphorescence
08:58

Cerebral Blood Oxygenation Measurement Based on Oxygen-dependent Quenching of Phosphorescence

Published on: May 4, 2011

15.2K

Tendinosis develops from age- and oxygen tension-dependent modulation of Rac1 activity.

Rowena McBeath1,2,3, Richard W Edwards2, Brian J O'Hara4

  • 1Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania.

Aging Cell
|April 3, 2019
PubMed
Summary

Hypoxia drives age-related tendon degeneration by altering tenocyte (tendon cell) behavior, leading to fibrochondrocyte and mineralized fibrochondrocyte phenotypes. This cellular change is linked to specific molecular pathways involving RhoA/Rac1 GTPase activity.

Keywords:
Rac1RhoAfibrochondrocytehypoxiatendinosistenocyte

More Related Videos

Quantifying the Modulation of Elastase Enzyme Activity Through Colorimetric Analysis
04:30

Quantifying the Modulation of Elastase Enzyme Activity Through Colorimetric Analysis

Published on: January 17, 2025

2.1K
Gait Analysis of Age-dependent Motor Impairments in Mice with Neurodegeneration
07:46

Gait Analysis of Age-dependent Motor Impairments in Mice with Neurodegeneration

Published on: June 18, 2018

12.6K

Related Experiment Videos

Last Updated: Jan 26, 2026

Cerebral Blood Oxygenation Measurement Based on Oxygen-dependent Quenching of Phosphorescence
08:58

Cerebral Blood Oxygenation Measurement Based on Oxygen-dependent Quenching of Phosphorescence

Published on: May 4, 2011

15.2K
Quantifying the Modulation of Elastase Enzyme Activity Through Colorimetric Analysis
04:30

Quantifying the Modulation of Elastase Enzyme Activity Through Colorimetric Analysis

Published on: January 17, 2025

2.1K
Gait Analysis of Age-dependent Motor Impairments in Mice with Neurodegeneration
07:46

Gait Analysis of Age-dependent Motor Impairments in Mice with Neurodegeneration

Published on: June 18, 2018

12.6K

Area of Science:

  • Biomedical Engineering
  • Cell Biology
  • Orthopedics

Background:

  • Age-related tendon degeneration (tendinosis) involves tenocyte phenotypic changes towards fibrochondrocytes.
  • Tendinosis is observed in vivo in areas with reduced tendon vascularity, suggesting hypoxia's role.

Purpose of the Study:

  • To investigate if hypoxia causes the tendinosis phenotype in tenocytes.
  • To determine if aging exacerbates hypoxia-induced tenocyte changes.
  • To elucidate the molecular mechanisms underlying hypoxia-driven tenocyte alterations.

Main Methods:

  • Human tenocytes (aged, tendinotic, young) were cultured under hypoxic conditions (1% O2).
  • Molecular mechanisms involving RhoA/Rac1 GTPase activity were investigated.
  • Pharmacologic and adenoviral manipulations were used in cell culture and tendon explants.

Main Results:

  • Hypoxia induced a mineralized fibrochondrocyte phenotype in aged tenocytes.
  • Young and tendinotic tenocytes developed a fibrochondrocyte phenotype under hypoxia.
  • Hypoxia-induced phenotypic changes were directly linked to RhoA/Rac1 GTPase activity, with distinct patterns in aged versus young cells.

Conclusions:

  • Hypoxia is a key driver of tenocyte phenotypic changes associated with tendinosis.
  • The study provides molecular insights into how aging and hypoxia contribute to human tendinosis development.
  • RhoA/Rac1 GTPase signaling is a critical mediator of hypoxia's effects on tenocyte phenotype.