Physics tip sheet #34 - April 1, 2003

April 01, 2003

1) Sickle cell disease
M.S. Turner, R.W. Briehl, F.A. Ferrone, R. Josephs
Physical Review Letters (Print issue: March 28, 2003)

Patients with sickle cell disease have mutant hemoglobin proteins that form long, stiff fibers inside red blood cells. Now, researchers propose a mathematical model to explain the persistent stability of these deadly fibers. The theory suggests that an inherent "twistiness" in the strands that make up the fibers could be the key to their durability and possibly to new treatments.

Physical Review Focus:
Journal article:

2) How treatments affect cancer growth
S. C. Ferreira Jr., M. L. Martinsy, M. J. Vilela
Physical Review E (to appear)

Chemotherapeutic strategies use quite different means to prevent cancer growth. Cytotoxic treatments directly kill cancer cells (and take some healthy cells with them). Antimitotic treatments do not kill cancer cells but stop the cell cycle at specific checkpoints. This paper looks at the differences these strategies have on the structure of cancerous growths by using computer models. For cytotoxic strategies, tumors can be completely eradicated, cease their growth or grow continuously, depending on the frequency and efficiency of individual treatments. However mitotic strategies cause a distinct change in the patterns of tumor growth. The types of changes seen are similar to when bacterial colonies exposed to non-lethal concentrations of antibiotics exhibit drastic changes in their growth patterns. Seeing as this behavior has not yet been seen in laboratory, the authors suggest that these observing these structural transitions may give important information about treatment efficacy. The authors are currently conducting some of those laboratory studies.

Journal article: Available to journalists on request

3) How does the Sun shine?
J. N. Bahcall, M. C. Gonzalez-Garcia, C. Pena-Garay
Physical Review Letters (to appear)

The sun generates energy through nuclear fusion but there is more than one way for this to occur. The standard solar model says that 98.5% of the energy comes from p-p chains (reactions of very light elements) and 1.5% comes from the CNO cycle (carbon atoms causing nitrogen and oxygen atoms to enter fusion reactions). However, until now, there has been no real demonstration about how much energy comes from which source, just the assumptions of a model. In fact, experiments allowed for the CNO cycle to generate anywhere up to 99.95% of the energy! New analysis of neutrino data from a range of experiments has allowed physicists to constrain the contribution of the CNO cycle from the 99.95% previous bound all the way down to 7.3%. To bring this limit down further will require direct measurements of neutrinos generated in the CNO cycle.

Physics News Update:
Journal article: Available to journalists on request

4) Electron searchlights from single molecules
Th. Weber, et al.
Physical Review Letters (to appear)

When electrons are knocked out of atoms, they usual fly off in many different directions. However, a process explored at the Lawrence Berkeley National Laboratory's Advanced Light Source shows how a single molecule (CO - carbon monoxide) can cause electrons to be emitted in a very well defined direction. The procedure works by essentially pulling the bottom electron from the pile in a carbon atom using an x-ray pulse. All the other electrons fall down to fill the gap and the energy released knocks another electron out. This electron is emitted along the line from the carbon atom toward the oxygen atom, creating the electron "searchlight". This process, called Auger emission has been known of since 1925 but this is the first observation of the strong focusing effect from a free molecule.

Journal article: Available to journalists on request

American Physical Society

Related Sickle Cell Disease Articles from Brightsurf:

Acute kidney injury among African Americans with sickle cell trait and disease
New research examines the risk of acute kidney injury in people with sickle cell trait or disease, as well as the effect of acute kidney injury on kidney function decline in these individuals.

New technology diagnoses sickle cell disease in record time
Researchers have developed a new way to diagnose diseases of the blood like sickle cell disease with sensitivity and precision and in only one minute.

Cannabis shows potential for mitigating sickle cell disease pain
Cannabis appears to be a safe and potentially effective treatment for the chronic pain that afflicts people with sickle cell disease, according to a new clinical trial co-led by University of California, Irvine researcher Kalpna Gupta and Dr.

Exploring mechanisms of resistance to HIV in people with sickle cell disease
A new analysis supports prior reports that people with sickle cell disease have lower rates of human immunodeficiency virus (HIV) infection, but follow-up cell studies did not reveal a mechanism to explain the reduced risk.

Light-to-moderate exercise may bring benefits for sickle cell disease
While exercise offers benefits for a wide range of health conditions, it has historically been considered too dangerous for people living with sickle cell disease (SCD).

Social determinant screening useful for families with pediatric sickle cell disease
Individuals with sickle cell disease (SCD) face the burdens of chronic illness and often racial disparities, both of which may increase vulnerability to adverse social determinants of health (SDoH).

Uncovering new therapeutic targets for airway inflammation in sickle cell disease
A new study by De, Agrawal, Morrone et al, challenges the common notion that airway in-flammation in Sickle Cell Disease (SCD) is secondary to asthma, even though the two disor-ders often coexist.

Researchers develop new method to rapidly, reliably monitor sickle cell disease
Researchers have developed a rapid and reliable new method to continuously monitor sickle cell disease using a microfluidics-based electrical impedance sensor.

Sickle cell disease needs more attention
Article signed by researchers affiliated with institutions in the US, UK, Ghana and Brazil highlights recent progress in diagnosis and treatment but warns that more screening of newborns is needed.

New genetic weapons challenge sickle cell disease
Researchers advancing gene-editing techniques to help patients with sickle cell disease discover an unexpected boost in fetal hemoglobin production, which mutes the effect of the disease.

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