Peripheral benzodiazepine receptors in the brain of cirrhosis patients with manifest hepatic encephalopathy. 2006

Peter Iversen, and Dorthe Aagaard Hansen, and Dirk Bender, and Anders Rodell, and Ole Lajord Munk, and Paul Cumming, and Susanne Keiding
PET Centre, Aarhus University Hospital, 8000 Aarhus, Denmark.

OBJECTIVE It has been suggested that ammonia-induced enhancement of peripheral benzodiazepine receptors (PBRs) in the brain is involved in the development of hepatic encephalopathy (HE). This hypothesis is based on animal experiments and studies of post-mortem human brains using radiolabelled PK11195, a specific ligand for PBR, but to our knowledge has not been tested in living patients. The aim of the present study was to test this hypothesis by measuring the number of cerebral PBRs in specific brain regions in cirrhotic patients with an acute episode of clinically manifest HE and healthy subjects using dynamic (11)C-PK11195 brain PET. METHODS Eight cirrhotic patients with an acute episode of clinically manifest HE (mean arterial ammonia 81 micromol/l) and five healthy subjects (22 micromol/l) underwent dynamic (11)C-PK11195 and (15)O-H(2)O PET, co-registered with MR images. Brain regions (putamen, cerebellum, cortex and thalamus) were delineated on co-registered (15)O-H(2) (15)O and MR images and copied to the dynamic (15)O-H(2)O and (11)C-PK11195 images. Regional cerebral blood flow (CBF) ((15)O-H(2)O scan) and the volume of distribution of PK11195 ((11)C-PK11195 scan) were calculated by kinetic analysis. RESULTS There were regional differences in the CBF, with lowest values in the cortex and highest values in the putamen in both groups of subjects (p<0.05), but no significant differences between the groups. There were no significant differences in the volume of distribution of PK11195 (V (d)) between regions or between the two groups of subjects. Mean values of V (d) ranged from 1.0 to 1.1 in both groups of subjects. CONCLUSIONS The results do not confirm the hypothesis of an increased number of PBRs in patients with HE.

UI MeSH Term Description Entries
D007546 Isoquinolines A group of compounds with the heterocyclic ring structure of benzo(c)pyridine. The ring structure is characteristic of the group of opium alkaloids such as papaverine. (From Stedman, 25th ed)
D008103 Liver Cirrhosis Liver disease in which the normal microcirculation, the gross vascular anatomy, and the hepatic architecture have been variably destroyed and altered with fibrous septa surrounding regenerated or regenerating parenchymal nodules. Cirrhosis, Liver,Fibrosis, Liver,Hepatic Cirrhosis,Liver Fibrosis,Cirrhosis, Hepatic
D008875 Middle Aged An adult aged 45 - 64 years. Middle Age
D001921 Brain The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM. Encephalon
D002250 Carbon Radioisotopes Unstable isotopes of carbon that decay or disintegrate emitting radiation. C atoms with atomic weights 10, 11, and 14-16 are radioactive carbon isotopes. Radioisotopes, Carbon
D006501 Hepatic Encephalopathy A syndrome characterized by central nervous system dysfunction in association with LIVER FAILURE, including portal-systemic shunts. Clinical features include lethargy and CONFUSION (frequently progressing to COMA); ASTERIXIS; NYSTAGMUS, PATHOLOGIC; brisk oculovestibular reflexes; decorticate and decerebrate posturing; MUSCLE SPASTICITY; and bilateral extensor plantar reflexes (see REFLEX, BABINSKI). ELECTROENCEPHALOGRAPHY may demonstrate triphasic waves. (From Adams et al., Principles of Neurology, 6th ed, pp1117-20; Plum & Posner, Diagnosis of Stupor and Coma, 3rd ed, p222-5) Encephalopathy, Hepatic,Portosystemic Encephalopathy,Encephalopathy, Hepatocerebral,Encephalopathy, Portal-Systemic,Encephalopathy, Portosystemic,Fulminant Hepatic Failure with Cerebral Edema,Hepatic Coma,Hepatic Stupor,Hepatocerebral Encephalopathy,Portal-Systemic Encephalopathy,Coma, Hepatic,Comas, Hepatic,Encephalopathies, Hepatic,Encephalopathies, Hepatocerebral,Encephalopathies, Portal-Systemic,Encephalopathies, Portosystemic,Encephalopathy, Portal Systemic,Hepatic Comas,Hepatic Encephalopathies,Hepatic Stupors,Hepatocerebral Encephalopathies,Portal Systemic Encephalopathy,Portal-Systemic Encephalopathies,Portosystemic Encephalopathies,Stupor, Hepatic,Stupors, Hepatic
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328 Adult A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available. Adults
D014018 Tissue Distribution Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios. Distribution, Tissue,Distributions, Tissue,Tissue Distributions
D049268 Positron-Emission Tomography An imaging technique using compounds labelled with short-lived positron-emitting radionuclides (such as carbon-11, nitrogen-13, oxygen-15 and fluorine-18) to measure cell metabolism. It has been useful in study of soft tissues such as CANCER; CARDIOVASCULAR SYSTEM; and brain. SINGLE-PHOTON EMISSION-COMPUTED TOMOGRAPHY is closely related to positron emission tomography, but uses isotopes with longer half-lives and resolution is lower. PET Imaging,PET Scan,Positron-Emission Tomography Imaging,Tomography, Positron-Emission,Imaging, PET,Imaging, Positron-Emission Tomography,PET Imagings,PET Scans,Positron Emission Tomography,Positron Emission Tomography Imaging,Positron-Emission Tomography Imagings,Scan, PET,Tomography Imaging, Positron-Emission,Tomography, Positron Emission

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