Flow Cytometery

cat_musculoskeletal_pathology.jpgFlow cytometers are machines constructed to measure and record flurescence on particles or cells stained with fluorochrome and flowing in suspension past an excitation source, typically a laser beam.

The fluorescence levels of the individual cells are captured by a photomultiplier tube, converted into an electric pulse, and stored and analyzed by a computer.

The cells can also be stained with multiple fluorochromes and can be excited by two different laser beams. This technique known as multiparameter flow cytometry, helps analyze several cellular components and their relationships.

Some other cellular features, such as light scattering at small angles, pulse width, or electrical conductivity, related to some extent to cell seize, can also be measured. [Read more...]

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Use of Electron Microscopy

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Examination of ultrastructural features of cellular and extracellular structures is a powerful diagnostic tool. The introduction of the transmission electron microscope in the early decades of the twentieth century dramatically expanded the investigative and diagnostic capabilities to study the submicroscopic details of diseased tissue including bone tumors and tumor like condition.

Use of the transmission through a thin section of tissue impregnated with electrondense material and embedded in plastic material and embedded in plastic medium is the most applicable for diagnostic purposes. [Read more...]

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Medicolegal and Anthropological Use of Bones

This topic is related more to Forensic sciences than anatomy but I felt like mentioning it here.

When a skeleton or isolated bones are received for medicolegal examination, one should be able to determine:

a Whether the bones are human or not;

b Whether they belong to one or more persons;

c The age of the individual;

d The sex;

e The stature and

f The time and cause of death. [Read more...]

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Helmets Reduce Risk of Head Injury In Skiers and Snowboarders

Skiers and snowboarders should always wear helmets to protect themselves from head injuries on the slopes, researchers say.

Findings from studies conducted in Canada and Norway, as well as the most recently conducted study in the U.S have all found evidence that ski helmets reduce the risk of head injury. [Read more...]

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Fractures Common After Osteoporosis Therapy Fails

Women who fail to respond to, or stop taking, their medication to fight the bone-thinning condition osteoporosis are at high risk of suffering a bone fracture, a new study suggests.

British researchers found that among nearly 2,000 older women with an “inadequate response” to osteoporosis medication, 9 percent suffered a fracture over the next year. [Read more...]

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Special Stains-Amyloid, Hemosiderin, Melanin and Calcium Stains

Amyloid stain

Staining for amyloid is one of the most useful special techniques. The Congo red stain and examination with nonpolarized and polarized light are the most frequently used techniques. The dye binds the beta-pleated arrangement of amyloid and has no chemical specificity.

This is seen as a reddish deposit under nonpolarized light. Green birefringence is present when the sections are examined under polarized light. Excessive or prolonged exposure to Congo red can cause binding to the tissue that is unrelated to the presence of amyloid. [Read more...]

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Special Stains-Trichrome and Stains For Microorganisms

Trichrome Stain

The trichrome stain is frequently used to demonstrate the presence of extracellular substances such as collagen. It is sometimes used in research investigation of soft and skeletal tissue, but is has minimal diagnostic applicabilities. As the name implies, the technique uses three dyes that stain nuclei, cytoplasm, and extracellular matrix, primarily the collagen.

This technique is rarely used in the diagnosis of tumors, but is frequently used for histomorphometric evaluation of mineralized versus nonmineralized osteoid in metabolic bone disease. [Read more...]

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Special Stains- Periodic Acid Schiff And Mucins

Fundamental to the diagnosis of bone tumors is the microscopic examination of formalin-fixed, calcified or decalcified tissue embedded in paraffin and stained with hematoxylineosin, interpreted in conjunction with clinical and radiographic data. Hematoxylin-eosin has proved to be one of the most enduring and reliable stains in the entire arsenal of techniques used in diagnostic pathology, including the diagnosis of skeletal conditions. [Read more...]

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Calcitonin

Calcitonin is the hypocalcaemic hormone discovered by Copp in 1962. It is a 32 amino acid single polypeptide produced by parafollicular ‘C’ cells of thyroid. Parathyroids, thymus and cells of medullary carcinoma of thyroid also contain calcitonin.

Synthesis and secretion of calcitonin is regulated by calcium concentration itself. Rise in plasma calcium increases while fall in plasma calcium decreases calcitonin release. [Read more...]

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An Overview of Parathyroid Hormone

Parathormone is stored in intracellular vesicles after its synthesis. Secretion of PTH is regulated by plasma Calcium concentration. Fall in plasma calcium induces parathormone release and rise inhibits secretion.

Changes in phosphate concentration in plasma affect parathormone secretion indirectly by altering Calcium concentration.

Parthyroid Hormone increases plasma calcium levels by increasing resorption of calcium from bone and decreasing the excretion of calcium in urine. It also promotes phosphate excretion which tends to supplement the hypercalcaemic effect. [Read more...]

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