Cytochemical study of abnormal intranuclear structures rich in beryllium

Area of Science:

• Toxicology
• Cell Biology
• Biochemistry

Background:

• Prolonged beryllium sulphate intoxication leads to the formation of intranuclear beryllium-rich structures (IBRS).
• These IBRS are primarily observed in kidney convoluted tubule cells.
• IBRS are characterized by dense granules approximately 20 nm in diameter.

Purpose of the Study:

• To elucidate the chemical composition of intranuclear beryllium-rich structures (IBRS).
• To investigate the nature of the granules within IBRS.
• To clarify the role of calcium, phosphorus, and proteins in IBRS formation and detection.

Main Methods:

• Electron probe microanalysis to determine elemental composition.
• High-resolution ion microanalysis for beryllium and protein localization.
• Cytochemical staining with thallium alcoholate and ethylenediaminetetraacetate (EDTA).
• Extraction with EDTA and RNase digestion on fixed tissue slices.

Main Results:

• IBRS were found to be rich in phosphorus and calcium.
• Granules within IBRS were identified as rich in beryllium and proteins.
• Cytochemical reactions were complicated by calcium and phosphorus presence.
• EDTA extraction and RNase digestion indicated calcium as the primary cause of positive staining and suggested a beryllium-binding protein component.

Conclusions:

• The positive response of IBRS to certain cytochemical techniques is mainly due to calcium.
• IBRS contain a beryllium-binding protein, potentially a highly phosphorylated acidic protein.
• These findings contribute to understanding the cellular mechanisms of beryllium toxicity.