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Biomedical subjects

P Ramirez

Publications and source records attributed to P Ramirez.

At least 37 records · Page 2Linked to original sources
PubMed2001

Genomic instability in a PARP-1(-/-) cell line expressing PARP-1 DNA-binding domain.

Poly(ADP-ribose) polymerase-1 (PARP-1) is a nuclear DNA binding protein that participates in processes involving nicking and resealing DNA strands. A genomically unstable subpopulation of PARP-1(-/-) cells has recently been described, which disappears after stable transfection of the cells with complete PARP-1 cDNA. Here we investigate the role played by PARP-1 in the maintenance of genomic stability, independently of its enzymatic activity. We used a PARP-1-deficient cell line to express a DNA construct encoding the PARP-1 DNA-binding domain (DBD) fragment and one encoding the mutant DBDbd-, defective in binding to DNA strand breaks. We found that, in the absence of DNA damage, expression of DBD or DBDbd- mutant induces increased genomic instability in the PARP-1(-/-) cells. These results suggest that the DBD fragment of PARP-1, apart from its classical role of nick detection and DNA binding, is likely to participate in molecular complexes with proteins involved in genomic integrity.

Base Sequence↗
PubMed2001

Molecular characterization of the genome of Maize rayado fino virus, the type member of the genus Marafivirus.

The complete nucleotide sequence of the single-stranded RNA genome of Maize rayado fino virus (MRFV), the type member of the genus Marafivirus, is 6305 nucleotides (nts) in length and contains two putative open reading frames (ORFs). The largest ORF (nt 97-6180) encodes a polyprotein of 224 kDa with sequence similarities at its N-terminus to the replication-associated proteins of other viruses with positive-strand RNA genomes and to the papainlike protease domain found in tymoviruses. The C-terminus of the 224-kDa ORF also encodes the MRFV capsid protein. A smaller, overlapping ORF (nt 302-1561) encodes a putative protein of 43 kDa with unknown function but with limited sequence similarities to putative movement proteins of tymoviruses. The nucleotide sequence and proposed genome expression strategy of MRFV is most closely related to that of oat blue dwarf virus (OBDV). Unlike OBDV, MRFV RNA does not appear to contain a poly(A) tail, and it encodes a putative second overlapping open reading frame.

Amino Acid Sequence↗
PubMed2001

Kinetics and characterization of cellular responses in the peritoneal cavity of mice infected with Taenia crassiceps.

Changes in the leukocyte population of the peritoneal cavity ensue immediately after infection with Taenia crassiceps metacestodes. Basophils and neutrophils decrease, whereas macrophages, monocytes, and lymphocytes increase to reach only modest levels by 6 wk and then diminish to nearly disappear by 15 wk when the parasite begins rapid reproduction. Eosinophils also appear early in infection, but then abate to lower levels that persist. In late infections, when the mass of cysticerci equals that of the mouse, the cysticerci grow among surprisingly few inflammatory cells. Mingling with the peritoneal inflammatory cells is a number of odd-looking cells that could correspond to the metaplasic mesothelial cells of the host or be of parasite origin. These cells are multinucleated, they aggregate in varigerated clusters, and form cystic structures in vitro; they also bind specific anti-T. crassiceps antibodies and specific T. crassiceps DNA probes in their nuclei. When the peritoneal cell exudate is reinjected intraperitoneally into naive mice, the odd-looking cells subsist for months, inducing in the host the synthesis of specific anti-T. crassiceps antibodies and immune resistance to challenge but do not reassemble into cysticerci even after 6 mo of inoculation. The early appearance and the immunogenic and antigenic properties of these odd-looking cells suggest they are important protagonists in the early host-parasite confrontation when the outcome of infection is set.

Animals↗
PubMed2001

In vitro and in vivo adenovirus-mediated p53 and p16 tumor suppressor therapy in ovarian cancer.

PURPOSE: The objectives of this study were to determine the effects of adenovirus-mediated p16 and p53 on growth and apoptosis in ovarian cancer cells and on survival in nude mice implanted with human ovarian cancer cells. EXPERIMENTAL DESIGN: SKOV-3 ip1 (p53 and p16 null), 2774 (p53 and p16 mutant), and OVCA 420 (p53 and p16 wild-type) cells were used for in vitro studies. SKOV-3 ip1, 2774, and Hey A8 (p53 and p16 wild-type) cells were used in the nude mouse studies. The E1-deleted adenoviruses containing p53, p16, or beta-galactosidase cDNA were transfected into the different cell types or inoculated into the nude mice after injection with ovarian cancer cells. RESULTS: Cell counting, microtetrazolium, and anchorage-independent growth assays on transfected cells demonstrated that p16 and the p16/p53 combination suppressed growth, whereas p53 did not (except in the anchorage-independent growth assay). Although cells infected with the p16/p53 combination had decreased growth compared with cells infected with either tumor suppressor alone, the difference was only statistically significant compared with p53. p16, p53, and the p16/p53 combination all increased apoptosis in the cells. In the nude mice, p16 treatment resulted in the longest survival for all three models, although it only reached statistical significance for the 2774 and SKOV-3 ip1 groups. CONCLUSIONS: Overall, p16 demonstrated greater growth inhibition than p53 both in vivo and in vitro. The p16/p53 combination demonstrated a consistent trend toward increased growth suppression and apoptosis over p16 or p53 alone. Adenovirus-mediated p16 may be a viable future treatment for ovarian cancer.

Adenoviridae↗
PubMed2000

Life-supporting human complement regulator decay accelerating factor transgenic pig liver xenograft maintains the metabolic function and coagulation in the nonhuman primate for up to 8 days.

BACKGROUND: It is not known whether the pig liver is capable of functioning efficiently when transplanted into a primate, neither is there experience in transplanting a liver from a transgenic pigs expressing the human complement regulator human complement regulator decay accelerating factor (h-DAF) into a baboon. The objective of this study was to determine whether the porcine liver would support the metabolic functions of non-human primates and to establish the effect of hDAF expression in the prevention of hyperacute rejection of porcine livers transplanted into primates. METHODS: Five orthotopic liver xenotransplants from pig to baboon were carried out: three from unmodified pigs and two using livers from h-DAF transgenic pigs. FINDINGS: The three control animals transplanted with livers from unmodified pigs survived for less than 12 hr. Baboons transplanted with livers from h-DAF transgenic pigs survived for 4 and 8 days. Hyperacute rejection was not detected in the baboons transplanted with hDAF transgenic pig livers; however, it was demonstrated in the three transplants from unmodified pigs. Baboons transplanted with livers from h-DAF transgenic pigs were extubated at postoperative day 1 and were awake and able to eat and drink. In the recipients of hDAF transgenic pig livers the clotting parameters reached nearly normal levels at day 2 after transplantation and remained normal up to the end of the experiments. In these hDAF liver recipients, porcine fibrinogen was first detected in the baboon plasma 2 hr postreperfusion, and was present up to the end of the experiments. One animal was euthanized at day 8 after development of sepsis and coagulopathy, the other animal arrested at day 4, after an episode of vomiting and aspiration. The postmortem examination of the hDAF transgenic liver xenografts did not demonstrate rejection. INTERPRETATION: The livers from h-DAF transgenic pigs did not undergo hyperacute rejection after orthotopic xenotransplantation in baboons. When HAR is abrogated, the porcine liver maintains sufficient coagulation and protein levels in the baboon up to 8 days after OLT.

Acute Disease↗
PubMed2000

Long-term results of liver transplantation in four siblings from the same family with familial amyloidotic polyneuropathy type I TTR Ala-71.

Familial amyloidotic polyneuropathy type I (FAP I) is a hereditary systemic amyloidosis usually involving the peripheral nervous system. In this paper we report our experience regarding the survival and the evolution of the sensory motor syndrome of the extremities and autonomic dysfunction in four siblings with the Ala-71 variant who were treated by liver transplantation (LT). The four siblings are alive 2-5 years after LT. After the operation, the seriated determinations of TTR-Ala-71 variant showed a constant decrease in serum levels in all cases. Our results support the proposal that LT should be indicated especially in forms with early clinical onset (3rd and 4th decades) and rapid progress to stop the neurological deterioration of the patients.

Adult↗