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Biomedical subjects

M Gayle

Publications and source records attributed to M Gayle.

At least 19 recordsLinked to original sources
PubMed1999

Monitoring gene expression profile changes in ovarian carcinomas using cDNA microarray.

The development of cancer is the result of a series of molecular changes occurring in the cell. These events lead to changes in the expression level of numerous genes that result in different phenotypic characteristics of tumors. In this report we describe the assembly and utilization of a 5766 member cDNA microarray to study the differences in gene expression between normal and neoplastic human ovarian tissues. Several genes that may have biological relevance in the process of ovarian carcinogenesis have been identified through this approach. Analyzing the results of microarray hybridizations may provides new leads for tumor diagnosis and intervention.

Cloning, Molecular↗
PubMed1998

Plasmodium gallinaceum: fluorescent staining of zygotes and ookinetes to study malaria parasites in mosquito.

We have developed a fluorescent labeling procedure for staining the mosquito stages of Plasmodium gallinaceum. PKH26, a lipophilic dye, is efficiently and permanently incorporated into the membranes of zygotes and ookinetes. Stained zygotes undergo normal development into ookinetes; the stain does not interfere with ookinete mobility or ability to adhere to the mosquito midgut lumen. Stained zygotes and ookinetes are comparable to untreated parasites in their ability to give rise to oocysts when fed to mosquitoes. This technique can be used to study the development of Plasmodium parasites in the complex cellular environment of the mosquito midgut after a blood meal. It may also be adapted to study other parasite-vector interactions.

Aedes↗
PubMed1994

Interleukin-1 activates p54 mitogen-activated protein (MAP) kinase/stress-activated protein kinase by a pathway that is independent of p21ras, Raf-1, and MAP kinase kinase.

In KB epidermoid cells, we previously showed that interleukin-1 alpha (IL-1) and various mitogens activate the mitogen-activated protein (MAP) kinases ERK1 and ERK2, which phosphorylate both myelin basic protein (MBP) and a peptide containing Thr669 of the epidermal growth factor receptor. In cell-free extracts made from gingival fibroblasts treated with platelet-derived growth factor or HepG2 hepatoma cells stimulated with phorbol myristate acetate, MBP and Thr669 kinase were both elevated 4-fold, and ERK1 and ERK2 were tyrosine-phosphorylated. In these cells IL-1 activated a kinase(s) that phosphorylated Thr669 peptide but not MBP and failed to cause tyrosine phosphorylation of ERK1/ERK2. Ceramide has been proposed as an intracellular mediator of IL-1 action, but C2-ceramide or sphingosine stimulated predominantly MBP-specific kinase activity in fibroblasts and had no effect in HepG2 cells. p54 MAP kinase (also called stress-activated protein kinase) is a c-Jun kinase first isolated from livers of cycloheximide-treated rats. After IL-1 stimulation, immunoprecipitates of lysates made from all three cell types with specific anti-p54 MAP kinase serum contained Thr669 and c-Jun phosphorylating activity, whereas precipitates from unstimulated cells contained no detectable p54 kinase activity. The major peak of IL-1-stimulated HepG2 Thr669 kinase activity co-chromatographed on Mono Q and phenyl-Superose with immunodetectable p54 MAP kinase. IL-1 did not cause p21ras activation in any cell type. Induction of Thr 669 kinase activity was not abrogated by elevation of cAMP levels, which has been shown to interfere with the activation of Raf-1. We could not detect MAP kinase kinase phosphorylating activity in unfractionated lysates made from IL-1-stimulated fibroblasts or HepG2 cells. KB cells contained a small amount of this activity, but it was not precipitated with an anti-Raf-1 antibody. We conclude that most of the IL-1-activated Thr669 kinase activity in fibroblasts and HepG2 cells, and a portion in KB cells, is due to p54 MAP kinase and that its activation is Ras-, Raf-, and MAP kinase kinase-independent.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1994

Plasma fatty acid levels in infants and adults after myocardial ischemia.

High levels of fatty acids are detrimental during reperfusion of ischemic hearts in part because of an inhibition of myocardial glucose use. We therefore measured plasma fatty acids during and after myocardial ischemia in both adult and pediatric patients. In adult patients undergoing thrombolytic therapy after an acute myocardial infarction, plasma fatty acids levels were elevated on admission to hospital (0.96 +/- 0.06 vs 0.40 +/- 0.01 mmol/L in healthy control subjects) and remained elevated throughout the initial 48 hours of hospitalization. In adult patients undergoing cardiac surgery, plasma fatty acids were markedly increased during surgery and at the time of the release of the aortic cross clamp (2.21 +/- 0.54 and 1.61 +/- 0.32 mmol/L, respectively). In children and infants (mean age 4.33 +/- 0.44 years) who had surgery to correct congenital heart defects, fatty acid levels during surgery increased to 3.27 +/- 0.26 mmol/L and remained elevated during immediate reperfusion (1.91 +/- 0.15 mmol/L) and for 24 hours after surgery (1.67 +/- 0.22 mmol/L). Because experimental studies have shown that high levels of fatty acids are detrimental to recovery of adult animal hearts, we determined the effect of high fatty acid levels on reperfusion recovery of isolated working hearts from 1-day-old rabbits perfused with 0.4 mmol/L palmitate (normal fat) or 1.2 mmol/L palmitate (high fat) and subjected to 50 minutes of global ischemia followed by aerobic reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Comparison of pH and carbon dioxide tension values of central venous and intraosseous blood during changes in cardiac output.

OBJECTIVE: To compare the pH and PCO2 values determined from of simultaneously corrected samples of central venous and intraosseous blood during sequential changes in cardiac output. DESIGN: Prospective, descriptive study. SETTING: An animal laboratory in a university medical center. SUBJECTS: Fourteen mixed breed 4-wk-old piglets. INTERVENTIONS: Animals were anesthetized with ketamine hydrochloride and neuromuscular blockade was induced by the administration of pancuronium bromide. After endotracheal intubation and the institution of mechanical ventilation, a 4-Fr pulmonary artery catheter and a carotid artery cannula were inserted via a cutdown into the right neck of each piglet. A 16-gauge intraosseous needle was inserted into the anteromedial surface of the right tibia. MEASUREMENTS AND MAIN RESULTS: Central venous and intraosseous blood gas samples were obtained simultaneously with thermodilution cardiac output measurements. Cardiac output measurements were as follows: during steady state (0.80 +/- 0.14 L/min), after volume loading of 15 mL/kg (1.00 +/- 0.25 L/min), after three successive bleeds of 15 mL/kg each at 30-min intervals (0.70 +/- 0.28, 0.54 +/- 0.22, and 0.43 +/- 0.16 L/min, respectively) and at exsanguination (unrecordable). Paired t-tests demonstrated no significant differences in pH and PCO2 values between intraosseous and central venous samples under all study conditions. Limits of agreement for difference in PCO2 between sites, within the range of cardiac outputs studied, were -12.86 to 11.38 torr (-1.71 to 1.46 kPa) and for pH were -0.09 to 0.15. CONCLUSIONS: Intraosseous blood samples can be obtained without difficulty even during extreme hypovolemia. The pH and PCO2 values of intraosseous and central venous blood samples were similar under all study conditions. Intraosseous blood may be a useful alternative to central venous blood to assess tissue acid-base status during hemorrhagic shock and other low-flow states.

Animals↗
PubMed1993

Surgical and postoperative management of two neonates with necrotizing fasciitis.

Two neonates who presented with necrotizing fasciitis (NF) secondary to omphalitis were treated by radical excision of the anterior abdominal wall. Postoperatively, renal failure in both children was managed by continuous arteriovenous hemofiltration (CAVH). One child survived; the other died of sepsis. Serum lactate levels, which were 10 to 15 times the normal levels in both infants postoperatively, decreased rapidly in the survivor, but never approached normal levels in the infant who died. Although the best prospect for survival in neonatal NF remains prompt, radical, surgical excision and is associated with a low threshold for repeat débridement, modern supportive measures (including CAVH) may enhance survival.

Acute Kidney Injury↗
PubMed1992

Vitamin K deficiency, intracranial hemorrhage, and a subgaleal hematoma: a fatal combination.

An exclusively breast-fed infant, who did not receive vitamin K prophylaxis at birth, presented with signs of raised intracranial pressure. Her clinical course was compounded by a lumbar puncture, which revealed blood in the cerebrospinal fluid, and a large subgaleal hematoma, which developed at the puncture site of an attempted scalp vein catheterization, resulting in coning, hypovolemic shock, and death. A major coagulopathy was present, probably caused by vitamin K deficiency. The necessity for vitamin K prophylaxis in all newborns and the timing of lumbar puncture in the critically ill child are discussed.

Catheterization, Peripheral↗
PubMed1990

Epitope mapping and use of anti-idiotypic antibodies to the L6 monoclonal anticarcinoma antibody.

Mouse monoclonal anti-idiotypic antibodies (anti-ids) were raised against L6, a murine IgG2a monoclonal antibody specific for a cell surface antigen expressed by many human carcinomas. Ten distinct anti-ids were generated. Eight anti-ids were shown to inhibit the binding of L6 to its target antigen and were characterized in detail. The heavy and light chain variable region gene segments of the monoclonal antibody L6 linked to human constant regions (chimeric L6) were expressed separately or together, to map the epitopes recognized by the anti-ids. Individual anti-ids were shown to recognize heavy chain, light chain, or combinatorial variable region determinants. Defining these specificities enabled us to select particular anti-ids for assays to monitor the pharmacokinetics of either murine or chimeric L6 antibodies in the circulation of human patients. A quantitative enzyme-linked immunosorbent assay developed with two anti-ids accurately detects less than 5 ng/ml. Anti-ids specific for light chain variable region-encoded determinants were capable of recognizing L6 antigen-binding fragments bound to the surface of human carcinoma cells. These anti-ids can be used to study the binding of chimeric L6 antibody at the surface of tumor cells in histological sections of tumor biopsies.

Animals↗
PubMed1989

Pediatric organ donor maintenance: pathophysiologic derangements and nursing requirements.

A retrospective chart review was conducted of 26 organ donors to determine hemodynamic and metabolic derangements encountered and nursing requirements for donor organ maintenance. There were 15 boys and 11 girls with a mean age 6.57 +/- 5.46 years. Mean donor maintenance time was 10.5 +/- 6.7 hours. Cardiorespiratory derangements included hypotension in 16, hypertension in 6, arrhythmias in 17 (premature ventricular contraction in 4, bradycardia in 8, paroxysmal atrial tachycardia in 3, and ventricular tachycardia in 2), asystolic events in 5, pulmonary insufficiency in 6, anemia in 8, and thrombocytopenia in 8. Metabolic and hormonal derangements included hyperglycemia in 18, hypokalemia in 20, hyperkalemia in 4, hyponatremia in 3, hypernatremia in 17, metabolic acidosis in 10, and diabetes insipidus in 15. Hypothermia (temperature 33.3 degrees +/- 0.4 degrees C, mean +/- SD) occurred in 14 donors. The mean physiologic Stability Index score was 22.2 +/- 4.7 and mean Therapeutic Intervention Score was 46.7 +/- 5.8. Total number of nursing hours spent in donor maintenance was 424.5 hours. Therapies offered included diuretics in 10, sodium bicarbonate in 8, antibiotics in 6, insulin in 12, pitressin in 13, verapamil in 3, isoproterenol in 3, dopamine in 17, and intravenous potassium boluses in 14. Of the potential 26 donors, 46 kidneys, 8 hearts, 14 livers, 3 pancreas, and 9 corneas were retrieved in transplantable condition. With appropriate donor maintenance, organs suitable for transplantation can be retrieved despite significant pathophysiologic derangements. Physicians intending to provide donor support should be comfortable with invasive monitoring and cardiorespiratory support and be prepared to provide a nurse to patient ratio of 2:1 at the bedside.

Adolescent↗
PubMed1988

Transcriptional activation of bacteriophage T4 middle promoters by the motA protein.

Transcriptional activation of middle genes in bacteriophage T4 requires the phage-encoded motA protein. Many middle genes are involved in deoxyribonucleotide biosynthesis and phage DNA replication. In the absence of motA, the gene products that are required for DNA synthesis are transcribed from other, upstream promoters. Using primer extension sequencing on RNA templates isolated from T4 motA+ and motA- infected cells, we have characterized 14 motA-dependent transcripts. The T4 middle promoters have a consensus sequence of nine base-pairs, (a/t)(a/t)TGCTT(t/c)A, spaced 11 to 13 nucleotides away from the Escherichia coli--10 consensus sequence, TAnnnT. The motA protein also can act as a transcriptional repressor for at least one early gene. Furthermore, the phage-encoded motA protein can activate in trans a middle promoter resident on a plasmid.

Base Sequence↗
PubMed1988

Intensive care course following liver transplantation in children.

We report the postoperative intensive care course of 16 children who underwent 18 orthotopic liver transplantation (OLT) procedures in London, Ontario and compare this experience in our developing transplant center with that reported from the Children's Hospital of Pittsburgh. Assisted ventilation was required in all children, with six requiring ventilation for greater than three days. Six children required positive end expiratory pressure (PEEP) therapy and hypertension was common. Physiologic stability index score was initially high in all patients, but fell on subsequent days. Intensive care survival was 100% with 69% long-term survival, which compared favorably with the information from Pittsburgh. Septic complications, despite immunosuppressive therapy were rare, but hypocalcemia and hypomagnesemia were common.

Adolescent↗
PubMed1988

CUUCGG hairpins: extraordinarily stable RNA secondary structures associated with various biochemical processes.

The mRNA of bacteriophage T4 contains a strikingly abundant intercistronic hairpin. Within the 55 kilobases of known T4 sequence, the hexanucleotide sequence CTTCGG is found 13 times in the DNA strand equivalent to mRNA sequences. In 12 of those occurrences, the sequence is flanked by inverted repeats predictive of RNA hairpins with UUCG in the loop. Avian myeloblastosis virus reverse transcriptase, which can traverse hairpins of larger calculated stability, terminates efficiently at these CUUCGG hairpins. Thermal denaturation studies of model hairpins show that the loop sequence UUCG dramatically stabilizes RNA hairpins when compared to a control sequence. These data, when combined with previously described parameters of helix stability, suggest that T4 has utilized this loop sequence to optimize the stability of intercistronic hairpins. The stability of CUUCGG hairpins is also utilized in the RNAs of many organisms besides T4.

Base Sequence↗
PubMed1987

Sequences and studies of bacteriophage T4 rII mutants.

We have sequenced more than 80 mutants of the bacteriophage T4 rIIA and rIIB genes. These include deletions about whose origin we have speculated, mutations affecting the rIIB promoters, various pseudo-revertants of the rII- phenotype, including mutations that bring about the reinitiation of translation following termination, mutations that affect regulation of rIIB translation by regA, the toxic minute plaquing mutants FC237 and FC238 and their detoxifiers, and many more of the classic frameshifts from the Cambridge collection. These mutants have been sequenced using dideoxy-mediated chain termination by either Escherichia coli DNA polymerase using single-stranded DNA as a template or by avian retroviral reverse transcriptase using mRNA or DNA as the template molecule. We list the sequence changes of the mutants with pertinent historic and phenotypic data. The mutants that facilitate translation reinitiation are discussed, and we discuss a model that could account for the generation of many of the mutations.

Base Sequence↗
PubMed1987

The bacteriophage T4 dexA gene: sequence and analysis of a gene conditionally required for DNA replication.

We have cloned and sequenced a bacteriophage T4 EcoRI fragment that complements T4 del (39-56) infections of an optA defective Escherichia coli strain. Bacteria containing this recombinant plasmid synthesize two new proteins with molecular weights of 9 and 26 kilodaltons. We have identified the gene encoding the 26 kilodalton protein as essential for T4 infections of optA defective E. coli. Genetic and biochemical results are consistent with the identification of this protein as the product of the dexA gene, which encodes a 3' to 5' exonuclease.

Amino Acid Sequence↗
PubMed1987

Mutations affecting translation of the bacteriophage T4 rIIB gene cloned in Escherichia coli.

Mutant ribosome binding sites of the bacteriophage T4 rIIB gene, resident on an 873 bp DNA fragment, were cloned into a plasmid vector as in-frame fusions to a reporter gene, beta-galactosidase. The collection of mutations included changes in the region 5' to the Shine/Dalgarno sequence, a mutation of the Shine/Dalgarno sequence, the alternate initiation codons GUG, AUA and ACG, and mutants in which several closely spaced initiation codons compete with each other on the same mRNA. The results show that the secondary structure variations we have installed 5' to the Shine/Dalgarno sequence have little effect on translation. GUG is essentially as good an initiator of translation as AUG when they are assayed on separate messages, but is outcompeted at least 50-fold in the sequence AUGUG. AUA and ACG are poor start codons, and are temperature sensitive. The initiation codon pair AUGAUA, in which the AUG is only two nucleotides from the Shine/Dalgarno sequence, displays a novel cold-sensitive phenotype.

Base Sequence↗