A post-hospital nursing home rehabilitation program.
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Aftercare↗
Biomedical subjects
A Brickner
Publications and source records attributed to A Brickner.
Functional domains of the alpha subunit of the eighth component of human complement: identification and characterization of a distinct binding site for the gamma chain.
The purified gamma subunit of the eighth component of human complement (C8) was used to characterize its site of interaction within C8 and to probe the ultrastructure of membrane-bound C5b-8 and C5b-9 complexes. Purification of gamma was accomplished by separating the disulfide-linked alpha-gamma subunit from the noncovalently associated beta chain and subjecting the former to limited reduction, alkylation, and ion-exchange chromatography. Upon mixing, purified alpha and gamma exhibited a high affinity for each other, as evidenced by their ability to form a noncovalent, equimolar complex at dilute concentrations and in the presence of excess serum albumin. Purified gamma also exhibited an affinity for C8', a previously described derivative that is functionally similar to C8 although it is composed of only alpha and beta. These results indicate that alpha possesses a specific site for interaction with gamma and that this site is preserved in the isolated subunit. Furthermore, this site remains accessible when alpha is associated with beta. In related experiments, gamma was found to specifically associate with membrane-bound C5b-8' and C5b-(8')9 complexes. These results indicate that the site for gamma interaction remains accessible on alpha in C5b-8' and is not shielded by C9 within C5b-(8')9. It is concluded that the gamma subunit of C8 is located on the surface of membrane-bound C5b-8 and C5b-9.
Binding Sites↗
Interobserver variability in EEG interpretation.
A random sample of 100 active electroencephalographers in the United States evaluated 10-second samples of 12 selected EEGs. The evaluations consisted of multiple-choice questions related to the age of the patient, EEG finding, artifact, and consciousness of the patient. The rate of reporting the "correct" response was examined in terms of various respondent characteristics such as EEG board certification, age, percent of time in clinical EEG work, and number of recordings interpreted annually. This study indicates that, even today, there is considerable variability in EEG interpretation, and that this variability is influenced by specific reader characteristics.
Action Potentials↗
Measurement of the ratio of the eighth and ninth components of human complement on complement-lysed membranes.
The mole ratio of the eighth (C8) and ninth (C9) components of human complement on membranes carrying the cytolytic C5b-9 complex was measured by direct binding assays. Erythrocytes from two different species were used as the membrane system. Antibody-treated sheep erythrocytes carrying a relatively small number of precursive membrane-bound C5b-7 complexes were prepared by exposure to human C8-depleted serum. These complexes were subsequently converted to C5b-8 by addition of saturating amounts of C8. Parallel binding assays using 125I-C8 were used to determine the exact amount bound and thus the number of C5b-8 complexes per cell. These cells were subsequently incubated with excess 125I-C9 and the amount bound relative to C8 on the membrane was measured. Results indicated the C8:C9 ratio remained constant at approximately 1:4 as the number of complexes varied from 40 to 310 per cell. Similar results were obtained regardless of whether C8 and C9 were added sequentially or simultaneously to cells bearing C5b-7. For comparison, experiments were also performed using membranes that contained a high number of complexes. Here, rabbit erythrocytes which carried approximately 25 000 C5b-7 per cell were incubated with limited amounts of C8 to form C5b-8 complexes on the membrane surface, the exact number of which was measured by 125I-C8 binding assays. When erythrocytes prepared in this manner were incubated with excess 125I-C9, the ratio of C8:C9 on the membrane was found to be essentially constant at approximately 1:3 as the number of these complexes varied from 50 to 4000 per cell.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Function of subunits within the eighth component of human complement: selective removal of the gamma chain reveals it has no direct role in cytolysis.
The eighth component of human complement (C8) consists of a disulfide-linked alpha-gamma dimer that is noncovalently associated with beta. Previous results from this laboratory established that two of these subunits have distinct roles in the cytolytic function of C8. Binding of C8 to the precursive C5b-7 complex is mediated strictly through beta while interaction between C8 and the lipid bilayer of target membranes occurs primarily through alpha. In the present study, we examined the importance of the gamma subunit in cytolysis by characterizing functional properties of C8', a derivative of C8 that lacks gamma. Preparation of this derivative was accomplished by limited cleavage of disulfide bonds in purified alpha-gamma and separation of alpha from gamma. When mixed, purified alpha and beta combined to form C8'. When tested for functional similarity to normal C8, the following results were obtained. (1) Specific and saturable binding of C8' to the C8 binding site on C5b-7 could be achieved. Significantly, the resulting C5b-8' supported subsequent C9 binding and cell lysis, which was equivalent to that observed with C5b-8. (2) Complement activation of (C8 + C9)-depleted serum containing C8' resulted in formation of SC5b-8'. Inclusion of C9 in the serum resulted in further conversion to SC5b-(8')9. These observations indicate that C8' is functionally similar to C8. Furthermore, they indicate that unlike alpha and beta, the gamma subunit has no direct role in facilitating C8 interaction with the nascent cytolytic complex or in mediating C9 binding and membrane lysis.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Clinical diagnoses and EEG interpretation.
A sample of 62 electroencephalographers in the United States evaluated 10-second samples of eight electroencephalograms. The evaluations were performed with and without knowledge of the clinical history. Evaluations consisted of multiple choice questions related to electroencephalographic observations, clinical diagnosis, and requests for additional tests such as computerized tomography and cerebrospinal fluid studies. The results indicate that clinical history influences interpretation, with considerable variation among readers in the number and type of additional tests requested.
Brain Diseases↗