Genome structure and expression of the ev/J family of avian endogenous viruses.

We recently reported the identification of sequences in the chicken genome that show over 95% identity to the novel envelope gene of the subgroup J avian leukosis virus (S. J. Benson, B. L. Ruis, A. M. Fadly, and K. F. Conklin, J. Virol. 72:10157-10164, 1998). Based on the fact that the endogenous subgroup J-related env genes were associated with long terminal repeats (LTRs), we concluded that these LTR-env sequences defined a new family of avian endogenous viruses that we designated the ev/J family. In this report, we have further characterized the content and expression of the ev/J proviruses. The data obtained indicate that there are between 6 and 11 copies of ev/J proviruses in all chicken cells examined and that these proviruses fall into six classes. Of the 18 proviruses examined, all share a high degree of sequence identity and all contain an internal deletion that removes all of the pol gene and various amounts of gag and env gene sequences. Sequencing of the gag genes, LTRs, and untranslated regions of several ev/J proviruses revealed a high level of identity between isolates, indicating that they have not undergone significant sequence variation since their introduction into the avian germ line. Although the ev/J gag gene showed a relatively weak relationship (46% identity and 61% similarity at the amino acid level) to that of the avian leukosis-sarcoma virus family, it retains several sequences of demonstrated importance for virus assembly, budding, and/or infectivity. Finally, evidence was obtained that at least some members of the ev/J family are expressed and, if translated, could encode Gag- and Env-related polypeptides.

The unique envelope gene of the subgroup J avian leukosis virus derives from ev/J proviruses, a novel family of avian endogenous viruses.

A new subgroup of avian leukosis virus (ALV), designated subgroup J, was identified recently. Viruses of this subgroup do not cross-interfere with viruses of the avian A, B, C, D, and E subgroups, are not neutralized by antisera raised against the other virus subgroups, and have a broader host range than the A to E subgroups. Sequence comparisons reveal that while the subgroup J envelope gene includes some regions that are related to those found in env genes of the A to E subgroups, the majority of the subgroup J gene is composed of sequences either that are more similar to those of a member (E51) of the ancient endogenous avian virus (EAV) family of proviruses or that appear unique to subgroup J viruses. These data led to the suggestion that the ALV-J env gene might have arisen by multiple recombination events between one or more endogenous and exogenous viruses. We initiated studies to investigate the origin of the subgroup J envelope gene and in particular to determine the identity of endogenous sequences that may have contributed to its generation. Here we report the identification of a novel family of avian endogenous viruses that include env coding sequences that are over 95% identical to both the gp85 and gp37 coding regions of subgroup J viruses. We call these viruses the ev/J family. We also report the isolation of ev/J-encoded cDNAs, indicating that at least some members of this family are expressed. These data support the hypothesis that the subgroup J envelope gene was acquired by recombination with expressed endogenous sequences and are consistent with acquisition of this gene by only one recombination event.

Independent isolates of the emerging subgroup J avian leukosis virus derive from a common ancestor.

A new subgroup of avian leukosis virus (ALV) that includes a unique env gene, designated J, was identified recently in England. Sequence analysis of prototype English isolate HPRS-103 revealed several other unique genetic characteristics of this strain and provided information that it arose by recombination between exogenous and endogenous virus sequences. In the past several years, ALV J type viruses (ALV-J) have been isolated from broiler breeder flocks in the United States. We were interested in determining the relationship between the U.S. and English isolates of ALV-J. Based on sequence data from two independently derived U.S. field isolates, we conclude that the U.S. and English isolates of ALV-J derive from a common ancestor and are not the result of independent recombination events.

Allied health faculty attitudes toward rural clinical practice.

Research findings of allied health practitioners' attitudes toward rural practice are limited. The purpose of this study was to identify attitudes of faculty members in a school of allied health toward rural vs. urban living, clinical education, and practice. A survey consisting of demographic and attitudinal questions was mailed to 233 faculty representing five professions. The response rate was 63.5%. The majority viewed rural living as having both positive and negative aspects. Placement of clinical students in rural areas was seen as enhancing rural recruitment. Rural professional issues were viewed as mixed with the most positive aspect being greater intellectual challenge. There were a few significant attitude differences by gender, age, years of experience, profession, hometown location, and practice location site. The findings of this study generally support previous research and contribute additional knowledge regarding attitudes toward rural practice. Further studies of allied health professionals appear warranted.

Satellite system addresses rural health problems.

The University of Nebraska Medical Center uses the recently established NEB*SAT state-owned satellite television system to transmit several types of educational presentations to rural Nebraska. The system represents the latest in a series of pioneering two-way television activities which have opened educational opportunities to students and professionals off-campus. Compressed video, transmitted via the NEB*SAT system, allows us to share credit courses in nursing and medical technology, administrative meetings, case conferences, and continuing education programs.

Nonesterified fatty acids modulate steroidogenesis in mouse Leydig cells.

The effects of nonesterified fatty acids (NEFA) in modulating testosterone synthesis stimulated by luteinizing hormone (LH, 10 ng/sample) were investigated in isolated adult mouse Leydig cells. LH-stimulated testosterone production was inhibited by triglycerides (0-500 mg/dl, 50 mg/dl, 94% of the control and 500 mg/dl, 40%) and by a mixture of NEFA (100 microM, 70% of control, 200 microM, 54%, and greater than 200 microM, less than 50%). Oleic acid was a more potent inhibitor than linoleic, stearic, or palmitic acids. 8-Bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP, 5 mM) stimulated testosterone production comparable to LH but failed to reverse the inhibition of steroidogenesis produced by the NEFA. The inhibition produced by NEFA was dependent on extracellular Ca2+; and a Ca2+ channel antagonist, verapamil (10 microM), enhanced the inhibition of chylomicrons and fatty acids. 22(R)-hydroxycholesterol (10 microM) reversed the inhibition produced by NEFA. The inhibitory effects of NEFA were reversible by removal of the fatty acids. The results indicate that NEFA are potent modulators of testosterone synthesis in Leydig cells stimulated with either LH, cAMP, or intracellular Ca2+. NEFA inhibit steroidogenesis at one of the steps preceding conversion of cholesterol to pregnenolone.

"Good" TV visuals: do they make a difference?

Media producers generally urge health science instructors to plan television visuals that conform to accepted ideas of what is "good" for television. Experiments in a class of nursing students taught entirely by television tested whether learning was affected by differences in visual aspect ratio, color, and seeing the instructor on the screen. It was found that alterations in these characteristics did not affect performances on post-tests, but the students did have definite preferences in some areas.

Using media in rural clerkships.

To enhance the educational value of rural clerkships for health professions students, the Biomedical Communications Division of the University of Nebraska Medical Center explored ways of providing instructional media to off-campus training sites. Faculty and community hospitals in rural areas were surveyed to identify appropriate topics. Videocassettes and slide-tape packages were previewed, evaluated, and purchased when acceptable. The packages were stored at Biomedical Communications. Off-campus faculty and students were encouraged to order media for use during preceptorships, but few took advantage of the opportunity. The greatest use of media occurred when packages were made available on-campus and students were encouraged to view them before or after rural clerkships.

Diagnostic value of a chemistry test profile.

Serum chemistry test results were correlated with discharge diagnoses of 4,295 persons admitted to an acute care general hospital in a seven-month period. The diagnostic value of the test results, separately and in combinations of up to 12 tests, were calculated at each of ten levels as measured from the mean of normal in standard deviations. All patients had a serum profile consisting of total calcium, inorganic phosphorus, glucose, urea nitrogen, uric acid, cholesterol, total protein, albumin, total bilirubin, alkaline phosphatase, lactic dehydrogenase, and glutamic oxaloacetic transaminase levels. Analysis by manual and computer technics is illustrated. Computerized analysis of a chemistry profile is reported as a list of diagnostic possibilities in ranking order, with the calculated probability for each. In this preliminary report individual diseases are replaced by categories of disease taken from The International Classification of Diseases, Adapted (ICDA).