Population screening and referral for hypercholesterolemia

To determine the potential effect of screening on referral patterns, an adult population sample (4,404 men, 5,164 women, 20-69 years of age) was systematically recruited and screened for hypercholesterolemia and then analyzed by different cholesterol referral recommendations. Using levels suggested by the Lipid Research Clinics Coronary Primary Prevention Trial (greater than or equal to 265 mg/dL), 7.3% of men and 5.8% of women would be referred for follow-up. With the suggested recommendations of the National Cholesterol Education Program (NCEP), (greater than or equal to 200 mg/dL), 49.2% of men and 40.2% of women would be referred. The use of age-related definitions of the NIH Consensus Conference on Lipid Lowering results in 28.0% referrals in men and 21.8% in women. From this population, hypercholesterolemia subjects (greater than or equal to 265 mg/dL at screening; n = 624) were invited for a second cholesterol determination (58% returned), which found 36% below the 265 mg/dL level. Population screening for cholesterol is likely to produce large numbers of patients for follow-up, with the actual numbers strongly dependent on cutoff levels and age-sex distributions. Referral and follow-up of these patients may place a significant load on an unprepared health care community.     

The potential for proton beam therapy in locally advanced carcinoma of the cervix.

Advanced cervix cancer has a local failure rate of 40-45% when treated with a combination of external beam irradiation and intracavitary implants, and approximately 60-65% when treated by external beam irradiation alone. Because of the absorption characteristics of protons, there is the potential for improved dose distributions and delivery of greater total doses to cervical neoplasms. Using computer-modelled examples, this theoretical advantage has been tested and the results have been extrapolated to show a therapeutic advantage in local control and morbidity. The first example shows the use of protons and intracavitary implants in advanced cervix tumors. Larger tumor doses are possible with protons than with photons, while the dose-volume to normal structures is decreased. In the second example, external proton beam treatment alone also reveals significantly higher tumor doses and lower normal tissue doses, compared to photon irradiation. With new proton therapy facilities being designed and built in the United States and overseas, protocols are being designed to evaluate the therapeutic potential of proton therapy in locally advanced cervix cancer.     

Imbalanced MHC class II molecule expression at surface of murine B cell lymphomas

To study the role of class II MHC expression in mouse lymphomagenesis, we examined the cell surface expression of I-A/E antigens on 24 spontaneous or murine leukemia virus (MuLV)-induced mouse B10.A (I-Ak, I-Ek) B cell lymphomas. Two primary B10.A B cell lymphomas were observed with strong I-Ek expression but with only minimal cell surface I-Ak expression. Both tumors are readily transplantable in syngeneic mice, with maintenance of their I-A-, I-E+ phenotype. Strikingly, one I-A-, I-E+ B cell lymphoma contains a (11; 17) translocation with a breakpoint on chromosome 17 that is localized within or very close to the H-2 complex. DNA of both tumors contains normal restriction enzyme fragments of the A alpha and A beta genes. Northern blot analyses indicated that one I-A-, I-E+ tumor strongly expressed A alpha, E alpha, and E beta mRNAs but possessed only a weak expression of A beta mRNA. The other B cell lymphoma showed A beta, E alpha, and E beta mRNA expression but only minimal A alpha mRNA expression. In 11 primary B10.A B cell lymphomas with a normal I-A+, I-E+ phenotype, no imbalances in A alpha/A beta mRNA levels were observed. The implications of these findings for the role of class II MHC expression in mouse B cell lymphoma-genesis are discussed.     

Freeze-preserved vein grafts and atherosclerosis. An experimental study

Histopathological changes of three types of vein grafts were studied. Freeze-preserved, fresh human grafts and autografts were inserted as patches in the aorta of rabbits on regular and variable cholesterol diets. In all grafts the endothelium and adventitia were reconstituted after a few months. In the wall, smooth muscle and elastic tissue were markedly diminished and poorly oriented with accompanied collagenisation. Cholesterol diet led to progressive fat and/or calcium deposition with subintimal proliferation in the autografts and fresh xenografts. In contrast this was seen to a much lesser degree and later in freeze preserved xenografts, even on higher cholesterol diets. Deep freezing considerably reduces the cellularity of the graft and its metabolic ability to accumulate lipids. Freeze-preserved veins seem to be a suitable graft for vascular reconstructions in severely atherosclerotic patients and compare favorably with vein autografts.     

The pathogenicity of Ab4p, the sequenced strain of equine herpesvirus-1, in specific pathogen-free foals.

The sequencing of the genome of equine herpesvirus-1 (EHV-1) is reported in Elizabeth A. R. Telford, Moira S. Watson, Kathryn McBride, and Andrew J. Davison, 1992, Virology, 189, 304-316. The sequence was derived using a plaque-purified clone of EHV-1 strain Ab4 (designated Ab4p). To ensure that Ab4p shares the pathogenic characteristics of parental Ab4 (hereafter Ab4), both were inoculated intranasally into foals, specifically free from EHV-1 and EHV-4. Clinical signs, including rectal temperature, were similar for both viruses. In addition, nasal shedding of virus was observed over a 1- to 2-week period postinfection, and viremia was established with both Ab4 and Ab4p. Isolation of virus from one foal following intravenous administration of steroids indicates that Ab4p can establish latency and undergo reactivation. Finally, retinal lesions were observed and these were similar to those seen with Ab4. In conclusion, several pathogenic characteristics of Ab4 are retained in the plaque-purified clone, Ab4p.