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M F Robert

Publications and source records attributed to M F Robert.

26 records · Page 2Linked to original sources
PubMed1984

Identification of Epstein-Barr nuclear antigen polypeptide in mouse and monkey cells after gene transfer with a cloned 2.9-kilobase-pair subfragment of the genome.

A new antigenic polypeptide was identified in mouse L cells and in monkey COS-1 cells in which Epstein-Barr nuclear antigen (EBNA) was expressed as the result of gene transfer with cloned fragments of Epstein-Barr virus (EBV) DNA. The same-size protein (Mr, approximately equal to 78,000) was seen in stably transformed mouse cells harboring only the BamHI K fragment [approximately equal to 5.2 kilobase pairs (kbp)] or its BamHI/HindIII subfragment, I1f (approximately equal to 2.9 kbp). Thus, the latter DNA fragment is sufficient to code for the protein. In transfected COS cells, a deletion mutant of the I1f fragment (approximately equal to 2.3 kbp) gave rise to a truncated protein (Mr, approximately equal to 52,000), whereas the BamHI K fragment yielded a full-sized Mr 78,000 species. This finding indicates that EBNA is encoded by viral genes. In Burkitt lymphoma lines or in immortalized lymphocytes, variation in the size of the I1f fragment correlated with the apparent molecular weight of the EBNA polypeptide. EBNA is truncated in two Burkitt lymphoma lines, Raji (Mr, 67,000) and P3JHR-1 (Mr, 70,000), which have deletion mutant I1f genes. EBNA in human lymphoid cells bearing a complete I1f fragment as part of the entire EBV genome is the same size (Mr, 78,000) as EBNA found after gene transfer of I1f alone into mouse or monkey cells. Therefore, these expression systems make an authentic EBNA after transfer of the appropriate EBV genes.

Animals↗
PubMed1984

Expression in COS-1 cells of Epstein-Barr virus nuclear antigen from a complete gene and a deleted gene.

In a previous study the BamHI-K fragment of Epstein-Barr virus DNA was shown to induce a nuclear antigen, Epstein-Barr virus nuclear antigen (EBNA), when cotransfected with the herpes simplex virus thymidine kinase gene into mouse LTK- cells. We have now inserted the BamHI-K fragment and a BamHI/HindIII subfragment, I1f , into shuttle vectors containing the origin of replication of simian virus 40. These plasmids have been introduced into COS-1, which are monkey kidney cells transformed by an origin-defective simian virus 40 genome. This expression system permitted rapid characterization of antigens, mRNAs, and proteins related to EBNA. The same-sized EBNA protein (approximately 78,000) was made after transfection with BamHI-K (5.2 kilobase pairs [kbp]) or the I1f subfragment (2.9 kbp). A deletion of about 600 bp occurred when the I1f fragment was propagated on the pSV2 plasmid in Escherichia coli. The deleted fragment gave rise to a smaller protein (approximately 52,000). These data provide evidence that EBNA is encoded by the 2.9-kbp I1f and is not an induced cellular protein. Nuclear antigen and polypeptide expression occurred equally well when the Epstein-Barr virus DNA was cloned on PSV2 -gpt or pSVOd . The latter plasmid lacks sequences allowing for efficient early gene transcription as well as splicing and polyadenylation signals which are present in pSV2 . Preliminary mapping of the EBNA gene transcripts demonstrated that two mRNAs (2.9 and 2.4 kilobases [kb]) are homologous to the I1f fragment. Taken together, the data suggest that the 2.9-kbp I1f fragment contains the structural gene for EBNA synthesis. COS-1 cells will thus provide a valuable system in which to analyze functional domains of the EBNA gene.

Animals↗
PubMed1976

Association between maternal diabetes and the respiratory-distress syndrome in the newborn.

Perinatal data on 805 infants of diabetic mothers and 10,152 infants of nondiabetic mothers were examined for a relation between maternal diabetes and respiratory-distress syndrome of the newborn. The syndrome occurred in 23.4 per cent of the diabetic vs. 1.3 per cent of the nondiabetic group. The risk of the syndrome in an infant of a diabetic mother was 23.7 times greater than that for an infant of a nondiabetic mother (P less than 0.00001). Further analysis to control for features associated with diabetes but also in themselves risk factors, such as gestational age and route of delivery, showed that respiratory-distress syndrome in infants of diabetic mothers was 5.6 times as likely to develop as in infants of nondiabetic mothers (P less than 0.00001). Thus, maternal diabetes mellitus per se predisposes to newborn respiratory-distress syndrome.

Adult↗
PubMed1975

Pulmonary pressure- volume relationships after corticotropin (ACTH) and salin injections in fetal rabbits.

ACTH mixed with barium sulfate injected into fetal rabbits on day 24 of a 31-day gestation was associated with increased lung maturity compared with lungs of noninjected controls when assessed by deflation pressure-volume curves and lung weight to body weight ratios measured on day 27. Fetuses injected with saline and barium sulfate also had accelerated (although somewhat less) lung maturation, perhaps from an ACTH-mediated response to stress. The ACTH group LA) maintained the largest lung volumes on deflation, followed by the saline group (B), the ACTH controls (C), and the saline controls (D). Volumes (percentage of total lung capacity) between the two injected groups and their controls (A versus C; B versus D) were significantly different at transthoracic pressures of 15, 10, 7, 4, 0, and -2 cm water (p less than 0.05). Volumes (percentage of total lung capacity) between the ACTH group and the saline group (A versus B) and between the two controls groups (C versus D) were not significantly different. Wet lung weight to body weight ratios were significantly different between the injected groups and their respective controls, between the two injected groups, and between the two control groups.

Adrenocorticotropic Hormone↗