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C Hinkley

Publications and source records attributed to C Hinkley.

11 recordsLinked to original sources
PubMed1994

Homeodomain protein MHox and MADS protein myocyte enhancer-binding factor-2 converge on a common element in the muscle creatine kinase enhancer.

MHox is a mesoderm-specific homeodomain protein that binds an A/T-rich element that is essential for activity of the muscle creatine kinase (MCK) enhancer. The MHox binding site also binds the ubiquitous homeodomain protein Oct-1 as well as myocyte enhancer-binding factor-2 (MEF2), which belongs to the MADS superfamily of transactivators. To determine which of these proteins activates MCK transcription through the A/T element, we mutated this sequence such that it would selectively bind MHox, MEF2, or Oct-1 and tested the activities of the mutant enhancers in skeletal muscle cells. These mutant enhancers revealed that only MEF2 is able to activate the MCK enhancer through the A/T element. The convergence of homeodomain and MADS proteins on the A/T element in the MCK enhancer provides a mechanism through which a single DNA sequence can mediate positive and negative regulation of gene transcription and is reminiscent of the roles of these two classes of transcription factors in the control of other cell-specific genes.

Animals↗
PubMed1992

Histone H2B gene transcription during Xenopus early development requires functional cooperation between proteins bound to the CCAAT and octamer motifs.

The ubiquitously expressed transcription factor Oct-1 and several other members of the POU domain protein family bind to a site, termed the octamer motif, that functions in the promoter and enhancer regions of a variety of genes expressed under diverse conditions. An octamer motif present in a conserved histone H2B-specific promoter element is required for S-phase-specific transcription of mammalian histone H2B genes in cultured cells. We have previously shown that the octamer motif in a Xenopus histone H2B gene promoter was inactive in nondividing frog oocytes. Here we show that the octamer motif, in addition to regulatory elements (TATAA, CCAAT, and ATF motifs) that are active in oocytes, is required for maximal H2B gene transcription in developing frog embryos. Factors binding to each of the H2B upstream promoter elements are present in oocytes and increase slightly in abundance during early development. The activity of the H2B octamer motif in embryos is not specifically associated with increased binding by Oct-1 or the appearance of novel octamer-binding proteins but requires the presence of an intact CCAAT motif. Our results indicate that synergistic interactions among promoter-bound factors are important for octamer-dependent H2B transcription. We suggest that the activity of the H2B promoter is regulated primarily by changes in the interactions between proteins already bound to the promoter rather than by alterations in their intrinsic abilities to bind DNA.

Activating Transcription Factors↗
PubMed1991

Continuous emotional support during labor in a US hospital. A randomized controlled trial.

The continuous presence of a supportive companion (doula) during labor and delivery in two studies in Guatemala shortened labor and reduced the need for cesarean section and other interventions. In a US hospital with modern obstetric practices, 412 healthy nulliparous women in labor were randomly assigned to a supported group (n = 212) that received the continuous support of a doula or an observed group (n = 200) that was monitored by an inconspicuous observer. Two hundred four women were assigned to a control group after delivery. Continuous labor support significantly reduced the rate of cesarean section deliveries (supported group, 8%; observed group, 13%; and control group, 18%) and forceps deliveries. Epidural anesthesia for spontaneous vaginal deliveries varied across the three groups (supported group, 7.8%; observed group, 22.6%; and control group, 55.3%). Oxytocin use, duration of labor, prolonged infant hospitalization, and maternal fever followed a similar pattern. The beneficial effects of labor support underscore the need for a review of current obstetric practices.

Adolescent↗
PubMed1991

A variant octamer motif in a Xenopus H2B histone gene promoter is not required for transcription in frog oocytes.

Xenopus oocytes, arrested in G2 before the first meiotic division, accumulate histone mRNA and protein in the absence of chromosomal DNA replication and therefore represent an attractive biological system in which to examine histone gene expression uncoupled from the cell cycle. Previous studies have shown that sequences necessary for maximal levels of transcription in oocytes are present within 200 bp at the 5' end of the transcription initiation site for genes encoding each of the five major Xenopus histone classes. We have defined by site-directed mutagenesis individual regulatory sequences and characterized DNA-binding proteins required for histone H2B gene transcription in injected oocytes. The Xenopus H2B gene has a relatively simple promoter containing several transcriptional regulatory elements, including TFIID, CBP, and ATF/CREB binding sites, required for maximal transcription. A sequence (CTTTACAT) in the H2B promoter resembling the conserved octamer motif (ATTTGCAT), the target for cell-cycle regulation of a human H2B gene, is not required for transcription in oocytes. Nonetheless, substitution of a consensus octamer motif for the variant octamer element activates H2B transcription. Oocyte factors, presumably including the ubiquitous Oct-1 factor, specifically bind to the consensus octamer motif but not to the variant sequence. Our results demonstrate that a transcriptional regulatory element involved in lymphoid-specific expression of immunoglobulin genes and in S-phase-specific activation of mammalian H2B histone genes can activate transcription in nondividing amphibian oocytes.

Animals↗
PubMed1990

Measurement of histone mRNA transcript abundance in Xenopus oocytes by a quantitative primer extension assay.

A quantitative primer extension method was used to measure the mass of histone gene transcripts in mature oocytes of the amphibian Xenopus laevis. The procedure, using a large excess of gene-specific oligonucleotide primer and continuous incorporation of a radiolabeled deoxynucleoside triphosphate precursor, is more sensitive and quantitative than primer extension assays employing end-labeled primers. It was determined that there are stoichiometric amounts, approximately 2 X 10(8) copies, of mRNA for each of the five major histone gene classes in mature Xenopus oocytes. These observations are consistent with a model whereby transcription of these genes is coordinately regulated in a cell cycle-independent manner during amphibian oogenesis.

Animals↗
PubMed1981

Nursing's image.

Explore the source record for details and available documents.

Nursing↗
PubMed1976

Amniotic fluid osmolality in pregnancies complicated by diabetes.

Amniotic fluid osmolality (AF Osm) was studied in 247 patients whose pregnancies were complicated by maternal diabetes. Significant increases in mean AF Osm accompanied pre-existing fetal as well as subsequent perinatal death. Abnormal increases in AF Osm were associated with a significant increase in risk of perinatal compromise with cumulative morbidity and mortality rates of 54 per cent. These data suggest that serial evaluation of AF Osm enables detection of a "higher risk" group of diabetic pregnancies in which perinatal death is more than doubled.

Adolescent↗
PubMed1975

Amniotic fluid creatinine in pregnancies complicated by diabetes.

Amniotic fluid (AF) creatinine concentrations, determined in 353 samples from 167 pregnancies complicated by maternal diabetes, are similar to those found at comparable gestation in uncomplicated pregnancy. Added maternal vascular disease significantly raises AF creatinine to such a degree that overestimation of fetal (renal) maturity is a clinical hazard if based solely on this parameter. Relative concentrations of creatinine in AF and maternal plasma (AF/MP ratio) are related to gestational age. Failure of AF creatinine to rise consistently on successive serial samples accompanies an increased risk of perinatal death in the pregnancy complicated by diabetes, four of five deaths in the present series following declines in this measurement.

Adult↗
PubMed1975

Total urinary estrogens in complicated pregnancies.

One hundred fifty-seven pregnancies complicated by different degrees of diabetes, toxemia, and hypertension were studied with serial urinary placental estrogen determinations. A simple and fast method for total placental estrogen determination was used. The level of total estrogen excretion was related to Apgar score in cases of class B diabetes, severe toxemia, and also in moderate toxemia when estrogen excretion was falling. Mean estrogen levels did not differ as a function of severity of diabetes. Levels did differ with severity of toxemia; however, only the difference in mean estrogen excretion between mild and severe toxemia was significant. Estrogen excretion was very low in hypertension but was not related to Apgar score. This study concludes that total urinary estrogens constitute only a single parameter necessary in the management of high-risk pregnancies.

Apgar Score↗