Evidence for two classes of chromatin-associated Epstein-Barr virus-determined nuclear antigen

A new class of Epstein-Barr virus nuclear antigen (EBNA) was identified by the complement fixation assay. This new species of EBNA is more tightly bound to chromatin and was termed class II EBNA, as opposed to the more weakly associated species, class I EBNA. Preparations of this new antigen(s) specifically reduced absorption with the titer of anti-EBNA antibodies as determined by the anticomplement immunofluorescence assay. Therefore, the complement fixation antigens (class II EBNA) appear to be related to the classical EBNA (class I EBNA). The class I EBNA was found to focus at the same pH (4.6) as the soluble antigen found in the cytosol. The class II EBNA differed from the class I EBNA with regard to its overall charge, molecular size, antigenicity, and affinity for chromatin. The class II EBNA appeared to be a basic protein, based on its apparent pI of 9.2 and its binding to cation-exchange resins. It differed from histones with regard to its molecular size (molecular weight between 60,000 and 70,000) and its elution from hydroxylapatite chromatography. Steps were taken to prevent proteolysis and artifacts in the immunological assays and in the overall charge estimation of the new antigen by nonspecific basic histone protein-acidic protein interactions. Both class I and class II EBNA were identified by radioimmunoelectrophoresis on two-dimensional polyacrylamide gels with pI values of 5.0 and 8.5, respectively, and a molecular weight range of 60,000 to 70,000 for both. A lower-molecular-weight antigen identified by molecular sieve chromatography appeared to be due to interference by histones in the immunoassays since it was not observed by the two-dimensional gel electrophoresis. Further characterization of this class II EBNA is in progress.

Dynamic body forces on axillary crutch walkers during swing-through gait

By means of dynamic analysis and a series of experiments, peak dynamic forces on subjects ambulating with axillary crutches are evaluated. For swing-through times of about one second, the subjects needed to support from 1.1 to 3.4 times their body weight at their hands; but the horizontal loads at their axilla were much less, varying from 3 to 11 percent of body weight. Such data can be useful in selecting axillary crutches with sufficient padding at the axilla to minimize pressure on the sensitive nerves and blood vessels in this area; and in predetermining whether a patient is strong enough to use crutches, since he must support more than his own weight.

Function and regulation of methionine5-enkephalin and its receptors in murine neuroblastoma cells

A homogeneous class of enkephalin receptors found in murine neuroblastoma clone N1E-115 (Chang, K.-J., and Cuatrecasas, P. (1979) J. Biol. Chem. 254, 2610-2618) has been confirmed using a centrifugation assay employing cellular membranes. In intact N1E-115 cells, synthetic methionine5-enkephalin inhibited prostaglandin E1-induced intracellular cyclic AMP formation in a naloxone-sensitive manner. Upon demonstrating intracellular methionine5-enkephalin immunocytochemically (Knodel, E., and Richelson, E. (1980) Brain Res. 197, 565-570), analyses of crude N1E-115 extract were made by radioimmunoassay or opiate receptor binding assay following fractionation by molecular sieve chromatography and high pressure liquid chromatography on a mu-Bondapak C18 column. Extracted methionine5-enkephalin immunoreactive material behaved similarly to synthetic methionie5-enkephalin in these analyses. Growth curve studies of the N1E-115 cells indicated that the quantity of methionine5-enkephalin immunoreactive material synthesized per milligram of cellular protein and the maximum number of enkephalin receptor sites per milligram of membrane protein increased as the cells progressed from logarithmic to stationary phase, with no change in the apparent affinity of the enkephalin receptors for [3H]methionine5-enkephalin. These data suggest that adrenergic clone N1E-115 has functional methionine5-enkephalin membrane receptors, that this clone synthesizes methionine5-enkephalin, and that both the enkephalin receptor number and the content of stored methionine5-enkephalin are regulated with respect to cell division.

Alcohol and drug addicted physicians: the scope of the problem

Alcoholism and drug addiction are occupational hazards in the practice of medicine. Reports from Canada, the U.S. and U.K. show a higher incidence of these problems in physicians than in the general population. This article reviews some characteristics of addicted doctors, including their backgrounds and reasons for starting the habit. The need for treatment to start as soon as the problem is discovered is emphasized. The prognosis for both alcoholism and drug addiction is good if the conditions are diagnosed early and treated vigorously.

Holographic interferometry applied to the measurement of displacements of the interior points of transparent bodies

Utilizing the light scattering property of transparent media, holographic interferometry is applied to the measurement of displacement at the interior planes of three dimensional bodies. The use of a double beam illumination and the introduction of a fictitious displacement make it feasible to obtain information corresponding to components of displacement projected on the scattering plane. When the proposed techniques are invoked, it is possible to eliminate the use of a matching index of refraction fluid in many problems involving symmetrically loaded prismatic bodies. Scattered light holographic interferometry is limited in its use to small changes in the index of refraction and to low values of relative retardation. In spite of these restrictions, a large number of technical problems in both statics and dynamics can be solved.

Strain analysis of a disk subjected to diametral compression by means of holographic interferometry

Two simultaneous holograms and several directions of observation are utilized to determine the components of displacement and strain in the disk. A reference strip is introduced to relate the fringe orders in the two holograms. A very good agreement is obtained between the holographic results and the elasticity theory solution. The obtained displacement field is estimated to be accurate to 8 x 10(-6) cm, which is approximately one-eighth the wavelength of the laser light utilized to obtain the holograms.

Ethanol metabolism in various racial groups

Eskimos and Indians, according to casual reports, take longer to sober up after an alcoholic debauch than do whites. We studied this apparent difference by administering ethanol to appropriate subjects and determining blood alcohol concentrations at intervals. We found the concentrations fell significantly faster in whites. Neither previous experience of alcohol nor general diet appeared to account for this difference, leaving genetic factors as the indicated cause.

Primary carcinoma of the liver in Alberta

A survey was made to determine the incidence and to elucidate the manifestations of primary carcinoma of the liver in Alberta. The findings were compared with other reported series. Ninety-six cases were identified: 69 hepatomas, 25 cholangiomas and two cholangiohepatomas. Seventy-four of the patients were male and 22 were female, a male preponderance of greater than 3:1. Ages ranged from 7 days to 92 years, but the majority of the patients (58%) were in the seventh and eighth decades. The incidence of associated cirrhosis (38.5%) was lower than that noted in most series.Hepatomegaly, abdominal pain, weight loss and ascites were the outstanding clinical features. Gastrointestinal hemorrhage was frequent and second only to hepatic failure as the immediate cause of death. An abdominal mass and pleural effusion occurred in higher frequency than that cited in the literature. Associated disorders included peptic ulceration and cholelithiasis.Surgical biopsy was superior to needle biopsy in establishing the diagnosis. Laboratory tests and routine radiographs may be of diagnostic aid.

Selection of students for admission to medical school: A two-class decision approach

The validity coefficient alone does not communicate sufficient information to estimate the errors in decisions to accept or reject candidates. By means of probability theory, it is demonstrated how information concerning errors in decisions may be estimated. With estimates of the frequencies of correct and incorrect decisions and the costs of such decisions, a utility index was defined, for which a minimum was sought as a function of the entrance requirement. Under the analytic criterion defined for utility, it was possible to determine for a number of cost systems the entrance score which would, in the long run, reduce losses to a minimum. The application of the model is illustrated using empirical data and hypothetical cost systems. For these data entrance requirements were determined according to the criterion in addition to selection ratios and probabilities of success.