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Biomedical subjects

G Khoury

Publications and source records attributed to G Khoury.

At least 181 records · Page 10Linked to original sources
PubMed1973

In vitro transcription of the viral-specific sequences present in the chromatin of cells transformed by simian virus 40.

Separated strands of simian virus 40 (SV40) DNA fragments were used in hybridization experiments to study the RNA transcribed by Escherichia coli RNA polymerase from the chromatin of cells transformed by SV40. The template activity of chromatin of the transformed cell line 11A8 (mouse-embryo cells) examined is about 17% that of purified DNA, suggesting that most of the chromatin DNA is repressed by chromosomal proteins. The SV40-specific RNA present in the RNA transcribed in vitro from 11A8 chromatin hybridizes specifically with the minus strand of SV40 DNA. Little or no reaction occurs with the plus strand of viral DNA. The SV40-specific RNA transcribed in vitro from chromatin of transformed cells shares sequences with the RNA produced during the early phase of SV40 lytic infection, and is similar to that present in the 11A8 cell line in vivo. Although the influence of chromosomal proteins on this pattern of transcription was not definitely determined, preliminary evidence indicates that an asymmetric pattern of transcription may also occur when 11A8 DNA is transcribed by E. coli RNA polymerase.

Animals↗
PubMed1973

Patterns of simian virus 40 deoxyribonucleic acid transcription. II. In transformed cells.

The pattern of simian virus 40 (SV40) deoxyribonucleic acid transcription has been examined in 11 SV40-transformed cell lines. In all cases, substantial regions of the minus strand (35-75%) appeared to be transcribed. In the lines tested, these regions included the "early" gene sequences. The SV40-specific ribonucleic acid from at least two of the transformed cell lines represented significantly greater portions of the minus strand than are represented in "early" lytic ribonucleic acid. Small regions of the plus strand appeared to be transcribed in only two of the transformed cell lines.

Animals↗
PubMed1972

Patterns of Simian Virus 40 DNA transcription after acute infection of permissive and nonpermissive cells.

Small amounts of fractionated, denatured, (32)P-labeled DNA from SV40 virus were incubated with a large excess of the complementary RNA of SV40 prepared in vitro with Escherichia coli RNA polymerase; the viral DNA strands were separated on hydroxyapatite columns. The RNA present in green monkey cells late in the lytic cycle reacted with 40-42% of the strand complementary to the in vitro complementary RNA (minus strand), and 60-64% of the opposite (plus) strand. "Early lytic" RNA failed to significantly interact with the plus strand, but formed stable duplex molecules with 35-39% of the minus strand. The RNA prepared from mouse embryo cells 24 hr after infection with SV40 combined with 35-38% of the minus strand and 60-62% of the plus strand. In all cases, the same regions of either the plus or minus strand appear to be transcribed in permissive and nonpermissive infections.

Animals↗
PubMed1972

Adenovirus-associated virus multiplication. IX. Extent of transcription of the viral genome in vivo.

Nucleic acid hybridization procedures were used to measure the extent of transcription of adenovirus-associated virus (AAV) deoxyribonucleic acid (DNA) in KB cells in the presence of either adenovirus or herpes simplex virus as the helper. Annealing of AAV ribonucleic acid to AAV DNA was monitored by a hybridization inhibition assay on nitrocellulose filters or by hydroxyapatite chromatography. These experiments confirmed the previous observation that, in the presence of either type of helper virus, only one strand of AAV DNA (the thymidine-rich or "minus" strand) is transcribed in vivo. However, it was found that only 70 to 80% of this strand appears to be transcribed in vivo. Furthermore, studies with minus strands employing hydroxyapatite chromatography and nuclease S(1), which specifically degrades single-stranded DNA, indicated that up to 20% of the minus strand is self-complementary. It seems likely that these self-complementary sequences account for the bulk of that portion of the minus strand (20 to 30%) which is not transcribed in vivo.

Adenoviridae↗
PubMedDate not supplied

Alternative RNA splicing in expression of the H-2K gene.

A major role of the classical transplantation antigens (designated class I antigens) is the presentation of virus-infected cells to cytotoxic T cells, a process that leads to the destruction of the cell displaying the viral antigen. Consistent with this function is the finding that these transplantation antigens (encoded by the H-2K, H-2D and H-2L genes in mice) are cell-surface glycoproteins with their amino-termini protruding extracellularly and their carboxy-termini located inside the cell. While the external domain is expected to provide biological specificity required for the associative presentation of viral antigens, the role of the cytoplasmic domain remains obscure. The recent observation that this latter region of the molecule is encoded by three separate DNA exons has suggested a complex role for this portion of the polypeptide chain. We have now obtained evidence for the use of alternative acceptor splice sites in the H-2K gene, resulting in two RNA transcripts that would encode H-2K antigens differing in their carboxy-termini. This is the first demonstration of the use of alternative splice acceptor sites in the same class I gene, and indicates the existence of different functional subsets of antigens encoded by the same gene.

Animals↗
PubMedDate not supplied

Laparoscopic colorectal resections. Initial experience at the AUB-MC.

BACKGROUND: Laparoscopic colorectal surgery has many advantages to offer. However, it is a complex procedure, and demands advanced technical skills and instrumentation. In addition, its safety when applied to malignant disease is debatable. In this article, we present the early experience and short term results of laparoscopic colorectal resections performed at the American University of Beirut Medical Center. PATIENTS AND METHODS: Between March 1997 and August 1998, 14 patients with various colorectal lesions underwent attempt at laparoscopic colorectal resection, at the American University of Beirut Medical Center. Seven patients were males (50%) and 7 were females (50%); their mean age was 59 yrs (range 40-73 yrs). Ten patients (72%) had malignant disease and 4 patients (28%) had benign disease. RESULTS: The operation was completed in 13 out of 14 patients (93%). The overall mean operative time was 176 min (range 135-270 min). The operation was taking less time as surgeons gained experience. The average hospital stay was 7.6 days (range 4-11 days). The last four patients, however, stayed less than six days in the hospital. There were no mortalities. There were three complications (21%), two patients had wound infection, and one patient had a prolonged ileus. All were managed conservatively. Ten patients had malignant disease. In these patients, the operative margins were clear of disease. The average number of lymph nodes retrieved was 10.4 (range 3-19). These patients were followed up for an average period of 7.4 months (range 1-16 months). There was one recurrence. There was no port site metastasis in any patient. CONCLUSION: Laparoscopic colorectal surgery is feasible and safe. The preliminary results are encouraging. Its application in malignant disease still awaits the results of prospective studies.

Adult↗