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Hirano body

Hirano body is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Hirano body rather than just read about it. In short: Hirano bodies are intracellular aggregates of actin and actin-associated proteins first observed in neurons (nerve cells) by Asao Hirano in 1965. The eponym ‘Hirano bodies’ was not introduced until 1968, by Schochet et al., three years after Hirano first observed the proteins.

Hirano body — main illustration
Hirano body — illustration

Key takeaways

  • Hirano body belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Hirano body to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Hirano body from memory before moving on to harder problems.

Reference excerpt

Hirano bodies are intracellular aggregates of actin and actin-associated proteins first observed in neurons (nerve cells) by Asao Hirano in 1965. The eponym ‘Hirano bodies’ was not introduced until 1968, by Schochet et al., three years after Hirano first observed the proteins. Hirano bodies are found in the nerve cells of individuals afflicted with certain neurodegenerative disorders, such as Alzheimer's disease and Creutzfeldt–Jakob disease. Hirano bodies were first described in the CA1 in patients with amyotrophic lateral sclerosis and parkinsonism-dementia complex (ALS-PDC). Hirano bodies (Hb) are found mostly in the neuronal processes in the pyramidal layer in the Sommer’s sector (CA1) of the hippocampus, mostly arising from age related changes in the microfilament system. Hirano bodies are often described as rod-shaped, crystal-like, and eosinophilic (pink after staining with haematoxylin and eosin). They are frequently seen in hippocampal pyramidal cells. An experimental model of Hirano body formation has been reported, using a genetically altered strain of the slime mold Dictyostelium discoideum. Hirano bodies have been noted as a function of age without obvious underlying neurodegeneration.

Alzheimer's disease The Sommer’s sector (CA1) of the hippocampus has been described to be influential in the formation of new memories, as well as, containing inclusion bodies that contribute to a hallmark of Alzheimer’s disease (AD), intellectual deficit. Alzheimer’s neurofibrillary tangles show a preference to form in the CA1, which is one of the major areas in which Hb’s have been observed. There are a larger number of Hb’s found in people with Alzheimer’s disease than those without the disease. Additionally many processes of Alzheimer’s neurofibrillary tangles have been observed to contain Hirano bodies. Hirano bodies are described as cytoplasmic paracrystalline lattices, which are a main form of a pathological feature seen in a broad spectrum of neurodegenerative diseases, such as Alzheimer’s disease (AD). There is an upregulation of a macroautophagic pathway related to AD that can be related to an actin aggregate thought to be an intermediate in the formation of Hirano bodies. More specifically the actin and actin binding proteins seen in Hirano bodies are a significant feature of an Alzheimer’s disease brain. Additionally, variations in the locational characteristics of β-amyloid precursor proteins seen in Alzheimer’s disease are connected to Hirano bodies. It was observed that Hirano bodies are a specific site of a C-terminal fragment of β-amyloid precursor proteins.

Notes

References Gajdusek, D. Carleton, Clarence J. Gibbs, Jr. and Michael Alpers. (1965) Slow Latent and Temperate Virus Infections. Bethesda: National Institutes of Health, National Institute of Neurological Diseases and Blindness. OCLC 463013735 Hirano, Asao (1994). "Hirano bodies and related neuronal inclusions". Neuropathol. Appl. Neurobiol. 20 (1): 3–11. doi:10.1111/j.1365-2990.1994.tb00951.x. PMID 8208338. S2CID 23942573.

External links Hirano Bodies Hirano bodies by "Who named it?" How a Slime Mold Came to the Aid of Alzheimer's Research

Illustrations

Hirano body: Hirano body as depicted in the histological slide from the Hippocampus of an elderly person with Alzheimer-related pathology. The Hirano body is the lighter pink ovoid in the center field of the image.
Hirano body as depicted in the histological slide from the Hippocampus of an elderly person with Alzheimer-related pathology. The Hirano body is the lighter pink ovoid in the center field of the image.

Worked examples

Example 1 — a first encounter with Hirano body

Start with the simplest possible case. Write down what Hirano body claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Hirano body before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Hirano body ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Hirano body

In research
Hirano body appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Hirano body in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Hirano body is common in secondary-school and first-year university syllabi. It links to neighbouring topics Histopathology, so understanding it makes those chapters shorter.
In everyday life
Look for Hirano body outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Hirano body in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Hirano body means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Hirano body out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Hirano body in simple terms?

Hirano bodies are intracellular aggregates of actin and actin-associated proteins first observed in neurons (nerve cells) by Asao Hirano in 1965. The eponym ‘Hirano bodies’ was not introduced until 1968, by Schochet et al., three years after Hirano first observed the proteins.

Why does Hirano body matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Hirano body?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Hirano body.

Tags

  • Histopathology

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