C Pellegrin | PubMed Health

PubMed1993

Heart rate variability and severe brain damage: preliminary data.

Severe brain damage may cause alterations of cardiovascular function: heart rate, particularly, require the integrity of the vagal, sympathetic and central nervous systems. We studied brain-heart functional relation and neurovegetative modulation by spectral analysis of heart rate variability (HRV). This technique allows separate evaluation of the sympathetic and vagal components of heart rate modulation. In order to correlate changes in HRV with brain damage, we performed 45 recordings in 6 patients (5/1 M/F) by means of autoregressive analysis (AAR). All patients were admitted to the ICU for severe brain damage (anoxic, traumatic or vascular). In 4 patients clinical outcome was brain death, in 2 permanent vegetative status. Two different patterns were found: one in patients with brain death, the other in patients with vegetative status. The small number of patients does not allow definitive conclusions from collected data, but that application of spectral analysis of HRV seems to be a useful monitoring of brain damage subjects.

Adolescent↗

PubMed1993

Culturing of primary hepatocytes as entrapped aggregates in a packed bed bioreactor: a potential bioartificial liver.

Conventional culture systems for hepatocytes generally involve cells cultured as flat, monolayer cells, with limited cell-cell contact, in a static pool of medium, unlike the liver in vivo where the parenchymal cells are cuboidal, with extensive cell-cell contact, and are continuously perfused with blood. We report here a novel bioreactor system for the culturing of primary hepatocytes with cuboidal cell shape, extensive cell-cell contact, and perfusing medium. The hepatocytes were inoculated into the bioreactor and allowed to recirculate at a rate optimal for them to collide and form aggregates. These newly-formed aggregates were subsequently entrapped in a packed bed of glass beads. The bioreactor was perfused with oxygenated nutrient medium, with controlled oxygen tension, pH, and medium perfusion rate. The hepatocytes were viable for up to the longest time point studied of 15 days in culture based on urea synthesis, albumin synthesis and cell morphology. Light microscopy studies of hepatocytes cultured for 15 days in the bioreactor showed interconnecting three-dimensional structures resembling the hepatic cell plate in the liver organ. Electron microscopy studies on the same cells revealed ultrastructure similar to the hepatocytes in vivo, including the presence of plentiful mitochondria, rough and smooth endoplasmic reticulum, glycogen granules, peroxisomes, and desmosomes. We believe that our hepatocyte bioreactor is a major improvement over conventional culture systems, with important industrial applications including toxicology, drug metabolism, and protein/peptide synthesis. The hepatocyte bioreactor concept may also be used as the basis for the development of a bioartificial liver to provide extracorporeal hepatic support to patients with hepatic failure.

Albumins↗