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Related Concept Videos

Phase Transitions02:31

Phase Transitions

23.3K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
23.3K
Properties of Transition Metals02:58

Properties of Transition Metals

30.0K
Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3–12 are transition elements. The f-block elements, also called inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is partially occupied before the f orbitals.
30.0K
Cooperative Allosteric Transitions01:58

Cooperative Allosteric Transitions

8.8K
Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand binds to any of these subunits, it triggers a conformational change that affects the binding sites in the other subunits; this can change the affinity of the other sites for their respective ligands. The ability of the protein to change the shape of its binding site is attributed to the presence of a mix of flexible and stable segments in the...
8.8K
Phase Transitions: Vaporization and Condensation02:39

Phase Transitions: Vaporization and Condensation

21.5K
The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. Vaporization occurs when the thermal motion of the molecules overcome the intermolecular forces, and the molecules (at the surface) escape into the gaseous state. When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules...
21.5K
Phase Transitions: Sublimation and Deposition02:33

Phase Transitions: Sublimation and Deposition

20.3K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
20.3K
Phase Transitions: Melting and Freezing02:39

Phase Transitions: Melting and Freezing

15.2K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
15.2K

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Pregnancy outcomes in women with classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

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Updated: Feb 10, 2026

Phase Transitions and Effect of Intermolecular Forces
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Phase Transitions and Effect of Intermolecular Forces

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Recent advances in 21-hydroxylase deficiency.

M I New, L S Levine

    Annual Review of Medicine
    |January 1, 1984
    PubMed
    Summary

    21-hydroxylase deficiency causes hormonal imbalances, leading to symptoms like pseudohermaphroditism. Genetic linkage to HLA antigens aids diagnosis, and hormone replacement therapy enables a normal life.

    Area of Science:

    • Endocrinology
    • Genetics
    • Reproductive Biology

    Background:

    • 21-hydroxylase deficiency impairs cortisol production in the adrenal cortex.
    • The salt-wasting form also involves inadequate aldosterone, leading to excess adrenal androgens due to a broken feedback system.
    • This results in hormonal and clinical symptoms, including pseudohermaphroditism and disordered puberty, with variable onset and severity.

    Purpose of the Study:

    • To summarize the pathophysiology, clinical presentation, genetic basis, diagnostic approaches, and treatment of 21-hydroxylase deficiency.
    • To highlight the genetic linkage with the human leukocyte antigen (HLA) complex and its diagnostic utility.
    • To underscore the availability and efficacy of prenatal diagnosis and hormone replacement therapy.

    Main Methods:

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    Transition Metals: Electron Configurations and Properties

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    • Review of existing literature on 21-hydroxylase deficiency.
    • Analysis of hormonal levels (baseline and stimulated) and genetic linkage studies.
    • Discussion of clinical manifestations and diagnostic criteria.

    Main Results:

    • 21-hydroxylase deficiency leads to insufficient cortisol and aldosterone, with excess androgens.
    • Genetic linkage to specific HLA-B antigens is observed in both classical and nonclassical forms.
    • Prenatal diagnosis is feasible for fetuses.
    • Glucocorticoid and mineralocorticoid replacement effectively manages symptoms.

    Conclusions:

    • 21-hydroxylase deficiency is an autosomal recessive disorder with significant clinical variability.
    • Genetic linkage to HLA and hormonal profiling are crucial for accurate diagnosis.
    • Timely diagnosis and appropriate hormone replacement therapy allow for normal development and life quality.