Carbohydrate dystrophies
This group of pathologies is based on a disorder of carbohydrate metabolism, specifically polysaccharides (which include glycogen and mucopolysaccharides) and glycoproteins (mucin and mucoids).
Polysaccharide metabolism disorders can manifest in three main variants:
- Decrease in carbohydrate content in cells. A classic example is the depletion of glycogen stores in diabetes mellitus.
- Complete absence of carbohydrates, which is characteristic of aglycogenosis.
- Accumulation of excess carbohydrates. This is observed in glycogen infiltration and various glycogenoses.
A separate category consists of glycoprotein metabolism disorders, which are also called mucous dystrophies. They are typified by the excessive accumulation of mucins and mucoids, causing the affected tissues to acquire a characteristic mucous consistency.
Dyspigmentoses (pigmentary dystrophies)
Cellular pigments are chromoproteins — complex compounds consisting of a protein and a chromophore. Disorders of their metabolism are called dyspigmentoses. The differentiation of these conditions is carried out according to several key criteria.
By origin, they are divided into primary (hereditary and congenital) and secondary (acquired in the postnatal period under the influence of pathogenic agents).
By mechanism of development, dystrophies caused by the following are distinguished:
- Defects in pigment metabolism enzymes (enzymopathies).
- Changes in the activity of enzymes responsible for the transport of pigments across cell membranes.
- Direct damage to cell membranes.
- Accumulation of excess pigments inside phagocytosing cells.
By chemical structure of the pigment, hemoglobinogenic (iron-dependent), proteinogenic (tyrosinogenic), and lipidogenic (lipoproteinogenic) disorders are distinguished.
Clinical manifestations may include the appearance of a pigment that should not normally be present, as well as an excess or deficiency of a physiological pigment. The process can be local (regional) or general (systemic).
Mineral metabolism disorders and thesaurismoses
Mineral dystrophies are associated with disordered metabolism of ions (calcium, potassium, iron, zinc, copper) and manifest as the intracellular accumulation of an excess of salts. Clinically significant examples include calcinoses, sideroses (iron metabolism disorder), and copper deposition in hepatolenticular degeneration (Wilson-Konovalov disease).
Thesaurismoses (storage diseases) are conditions in which an excess of various substances accumulates in cells, disrupting metabolic and plastic processes, as well as cell structure and function. Virtually all thesaurismoses are the result of hereditary enzymopathies with an autosomal recessive inheritance pattern.
Lysosomal and peroxisomal storage diseases are distinguished. The classification is based on the type of accumulating substances:
- Lipid (lipidosis) and glycogen (glycogenosis) storage diseases are the most common forms.
- Amino acid and nucleoprotein storage diseases.
- Mucopolysaccharide (mucopolysaccharidosis) and mucolipid (mucolipidosis) storage diseases.
Dysplasia and cell death
Dysplasia is a disorder of cell differentiation accompanied by persistent changes in its structure, metabolism, and function. Differentiation is determined by a genetic program, and its realization depends on the interaction of the nuclear genome, cytoplasm, microenvironment, and the influence of biologically active substances. With the same genetic deviation, the manifestations of dysplasias can vary. In clinical practice, many cellular dysplasias are regarded as precancerous conditions, as they underlie tumor growth.
The final stage of cellular dystrophies or the consequence of the direct action of damaging factors is necrosis — the irreversible cessation of vital activity of a severely damaged cell. Necrosis is always accompanied by perifocal inflammation.
It is preceded by two stages:
- Paranecrosis — metabolic and structural changes are still reversible.
- Necrobiosis — changes acquire an irreversible character and lead to death.
In addition to necrosis and apoptosis, modern data distinguish specific variants of death: necroptosis, pyroptosis, and ferroptosis. Cell death can also occur under physiological conditions (e.g., the elimination of spent immunocytes or lactocytes).
Briefly: answers to topical questions
What types of hemoglobinogenic pigments exist in normal and pathological conditions?
Hemoglobinogenic pigments, depending on the conditions of their formation and accumulation in the body, are classified into two groups: physiological and those arising exclusively in diseases.
- Formed normally — hemoglobin, ferritin, hemosiderin, bilirubin.
- Formed only in pathology — hematoidin, hematins, porphyrins.
Which diseases belong to lipid thesaurismoses (lipidoses)?
Hereditary parenchymal lipid thesaurismoses (lipidoses) include a group of storage diseases arising due to a genetic deficiency of enzymes.
- Cerebroside lipidosis — Gaucher disease.
- Sphingomyelin lipidosis — Niemann-Pick disease.
- Ganglioside lipidosis — Tay-Sachs disease.
- Generalized ganglioside lipidosis — Norman-Landing disease.
- Glycosphingolipidosis — Fabry syndrome (Fabry-Anderson disease).
- Sulfatidosis — leukodystrophies.
What types of calcification (calcinosis) are distinguished by the mechanism of development?
By the mechanism of development, two main types of pathological calcification are distinguished.
| Type of calcification | Blood Ca level | Tissue state |
|---|---|---|
| Dystrophic | Normal | Damaged, necrotic, or sclerosed |
| Metastatic | Elevated (hypercalcemia) | Initially unchanged tissue |
What processes belong to parenchymal protein dystrophies (dysproteinoses)?
Parenchymal protein dystrophies (dysproteinoses) are represented by several morphological types, most of which are sequential stages of increasing cell damage.
- Granular dystrophy serves as the morphological substrate of cellular swelling.
- Hyaline-droplet dystrophy is a stage of progressive protein metabolism disorder.
- Hydropic dystrophy is a stage of metabolic disturbance often leading to cell necrosis.
- Horny dystrophy (hyperkeratosis) is the excessive formation of cornified substance normally or its appearance in atypical sites.
Class and exam questions
What is the difference between paranecrosis and necrobiosis?
Paraneucrosis is the initial stage of profound cell damage where metabolic and structural shifts are still reversible. Necrobiosis represents irreversible changes that inevitably end in cell death.
What are thesaurismoses and why do they occur?
These are storage diseases characterized by the intracellular accumulation of an excess of certain substances (lipids, glycogen, etc.). They are almost always caused by hereditary enzymopathies with an autosomal recessive inheritance pattern.
How are dyspigmentoses classified by their development mechanism?
They are subdivided into pathologies caused by enzymopathies, membrane transport defects, direct damage to cell membranes, and the excessive accumulation of pigments in phagocytic cells.
What else to study on this topic
- Mechanisms of development of mucous dystrophies and glycoprotein metabolism
- Lysosomal and peroxisomal storage diseases
- Modern classification of types of cell death (necroptosis, pyroptosis, ferroptosis)
- The role of the nuclear genome and microenvironment in the development of cellular dysplasias
- Pathogenesis of hepatolenticular degeneration (Wilson's disease)
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