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Biomedical subjects

R Samara

Publications and source records attributed to R Samara.

6 recordsLinked to original sources

Palatal discrepancies and postdams.

To investigate the variation in post-cure palatal discrepancy of dentures, 20 complete maxillary replica dentures were prepared on models with high and low palates and processed by conventional compression moulding and injection moulding. Measurements were made by travelling microscope of the sagittal midline discrepancies between palate and model on three occasions; after processing; after removal of part of the investing plaster; and after immersion in water for 1 month at 37 degrees C. The magnitudes of discrepancies were greatest distally, diminishing with distance anteriorly from the postdam. They increased with partial removal of plaster, and decreased slightly after immersion.

Acrylic Resins↗

Carcinoembryonic antigen promotes tumor cell survival in liver through an IL-10-dependent pathway.

Most circulating tumor cells die within 24 h of entering the hepatic microvasculature because their arrest initiates an ischemia-reperfusion (I/R) injury that is cytotoxic. Human colorectal carcinomas (CRC) produce the glycoprotein Carcinoembryonic Antigen (CEA) that increases experimental liver metastasis in nude mice. Since CEA induces release of IL-6 and IL-10, we hypothesized that CEA inhibits the I/R injury through a Kupffer cell-mediated cytokine-dependent pathway. We assessed cytokine effects in CRC co-cultured with liver and in vivo. Human CRC prelabeled with fluorescent dyes were incubated with a reoxygenated suspension of ischemic nude mouse liver fragments in a bioreactor. CEA, rhIL-6 or rhIL-10 were either administered to the donor mice prior to hepatic ischemia or during co-culture. Liver donors were athymic nude or iNOS, IL-6 or IL-10 knock out mice. Ischemic-reoxygenated liver kills Clone A CRC through production of nitric oxide (NO) and superoxide anion. Treatment of liver donors with CEA prior to hepatic ischemia inhibited this in vitro cytotoxicity through an IL-10 and Kupffer cell dependent pathway that inhibited NF-kappaB activation, NO production and iNOS upregulation. IL-10 but not IL-6 enhanced CRC survival in nude mouse liver in vivo. Thus, CEA enhanced metastasis by inducing IL-10 to inhibit iNOS upregulation in host liver.

Animals↗

Progressive multifocal leukoencephalopathy in a patient with hypogammaglobulinemia.

We describe a child with congenital hypogammaglobulinemia that was diagnosed at 13 months of age. When he was 4 years old, gait disturbances began. The main neurological manifestations were progressive spastic tetraparesis and intellectual and speech deterioration. No infectious agent was identified. A magnetic resonance imaging scan of the central nervous system revealed periventricular demyelinating areas in the frontal, temporal, and parietal lobes with cortical atrophy. Stereotactic brain biopsy confirmed the diagnosis of progressive multifocal leukoencephalopathy caused by JC virus. He was treated with intravenous and intraventricular cytarabine and interferon-alpha, and there was clinical improvement. We emphasize the need for brain biopsy as soon as a neurological complication is suspected in patients with congenital hypogammaglobulinemia for whom cerebrospinal cultures or polymerase chain reaction analyses are negative.

Agammaglobulinemia↗

Poly(ADP-ribosyl)ation of p53 in vitro and in vivo modulates binding to its DNA consensus sequence.

The tumor-suppressor p53 undergoes extensive poly(ADP-ribosyl)ation early during apoptosis in human osteosarcoma cells, and degradation of poly(ADP-ribose) (PAR) attached to p53 coincides with poly(ADP-ribose)polymerase-1, (PARP-1) cleavage, and expression of p53 target genes. The mechanism by which poly(ADP-ribosyl)ation may regulate p53 function has now been investigated. Purified wild-type PARP-1 catalyzed the poly(ADP-ribosyl) of full-length p53 in vitro. In gel supershift assays, poly(ADP-ribosyl)ation suppressed p53 binding to its DNA consensus sequence; however, when p53 remained unmodified in the presence of inactive mutant PARP-1, it retained sequence-specific DNA binding activity. Poly(ADP-ribosyl)ation of p53 by PARP-1 during early apoptosis in osteosarcoma cells also inhibited p53 interaction with its DNA consensus sequence; thus, poly(ADP-ribosyl)ation may represent a novel means for regulating transcriptional activation by p53 in vivo.

Apoptosis↗

Using parity-progression ratios to estimate the effect of female sterilization on fertility.

In this article, a new methodology that employs parity-progression ratios to estimate the effect of female sterilization on fertility is described, and results using data from Ecuador are compared to those obtained using a previously existing approach that classifies women by marital duration. The methods differ in how they disaggregate marital fertility and in the assumption they make about what the subsequent fertility of sterilized women would have been if they had not been sterilized. The analysis of the Ecuadoran data shows that the estimate of births averted by sterilization has diminished over time, even as sterilization prevalence has been increasing. This situation is attributed to a decline in the fertility of nonsterilized women resulting from increased use of reversible methods of contraception.

Adolescent↗

Impact of publicly funded contraceptive services on unintended pregnancies and implications for Medicaid expenditures.

Of U.S. women who use a reversible method of contraception, 24% each year obtain family planning services from a publicly funded clinic or a private doctor reimbursed by Medicaid. If these subsidized contraceptive services were not available, women who currently use them would have an estimated 1.3 million additional unplanned pregnancies annually, of which 29% would involve women aged 15-19, 67% would involve never-married women and 61% would involve women with a household income below 200% of the federal poverty level. An estimated 632,300 of these pregnancies would end in induced abortion, an increase of 40% over the current national level. Another 533,800 pregnancies would result in unintended births. Some 76,400 of these would be births to families already receiving public assistance, and 64,100 would be to families that would become eligible for public assistance because of the birth; another 197,000 would be to women whose families would not receive public assistance, but would be eligible for Medicaid coverage of pregnancy, delivery and newborn care. In FY 1987, public-sector expenditures for contraceptive services totaled an estimated $412 million. If subsidized services had not been available, the federal and state governments would have spent an additional $1.2 billion through their Medicaid programs for expenses associated with unplanned births and abortions. Thus, for every dollar spent to provide publicly funded contraceptive services, an average of $3.00 was saved in Medical costs for pregnancy-related health care and medical care for newborns.

Abortion, Induced↗