Biomedical subjects

J P Patrick

Publications and source records attributed to J P Patrick.

4 recordsLinked to original sources

PubMed1994

Biliary ultrastructural changes in the liver in a case of giant cell arteritis.

A 55-yr-old Palestinian man was admitted with a 1-month history of bi-temporal headache, proximal weakness and myalgia in the lower limbs. Both temporal arteries were swollen and tortuous. There was a moderate degree of cholestatic hepatic dysfunction. Temporal artery biopsy showed typical features of giant cell arteritis. Light microscopic examination of the liver showed no significant abnormality while electron microscopic (EM) examination revealed ultrastructural damage to the bile canaliculi. The patient improved dramatically on steroid therapy with normalization of cholestatic dysfunction. EM examination of a repeat liver biopsy 8 months later showed complete reversal of the biliary ultrastructural damage. The pathogenesis of the biliary injury remains uncertain.

Bile Canaliculi↗

PubMed1989

Automated rule based graded analysis of ambulatory cassette EEGs.

We describe algorithms, developed on a PDP-11/73 microcomputer, which identify spikes/sharp waves (STs), spike-and-wave complexes (SSWs), artifacts and background activity in 4-channel ambulatory EEGs. The algorithms were trained using 40 database segments. Time domain/mimetic methods were used and semantic rules, based on morphology and multi-channel contextual information, were developed to mimic the principles used in visual interpretation. The likelihood of STs/SSWs being genuine was graded from 10 to 1. This approach avoids forced classification of each event as genuine ST/SSW or not. The algorithms were then evaluated using 60 independent segments. STs/SSWs graded greater than 7 had significantly higher probability (P less than 0.005) of being genuine than those graded less than or equal to 7. Less than 4% of STs/SSWs identified by both electroencephalographers were missed. None was distinct. All 113 artifacts resembling STs/WWs were graded less than or equal to 7. Classification of 969/1117 (86%) waves in the background matched that of one electroencephalographer. The algorithms can be extended to 8- or more-channel EEGs.

Algorithms↗

PubMed1987

Computer database of ambulatory EEG signals.

The paper describes an ambulatory EEG database. The database contains segments of AEEGs done on 45 subjects. Each epoch (1/8th second or more) of AEEG data has been annotated into 1 of 40 classes. The classes represent background activity, paroxysmal patterns and artifacts. The majority of classes have over 200 discrete epochs. The structure is flexible enough to allow additional epochs to be readily added. The database is stored on transportable media such as digital magnetic tape or hard disk and is thus available to other researchers in the field. The database can be used to design, evaluate and compare EEG signal processing algorithms and pattern recognition systems. It can also serve as an educational medium in EEG laboratories.

Adolescent↗

PubMed1985

Artifacts in ambulatory cassette electroencephalograms.

Most artifacts in ambulatory electroencephalograms (AEEGs) are similar to those seen on conventional electroencephalograms (CEEGs) and can be identified as such. Some artifacts may simulate epileptiform or slow wave EEG activity and may occur asymmetrically or focally. We have described the use of a dual write-out method for identifying and detecting the source of artifacts in AEEGs. This technique has improved the quality of AEEGs and facilitated interpretation.

Adolescent↗