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Biomedical subjects

D S Wagner

Publications and source records attributed to D S Wagner.

At least 19 recordsLinked to original sources
PubMed2002

Potency and sterility of anesthetic drugs in obstetric anesthesia.

In order to estimate how long a medication can remain prepared before the integrity or concentration of the drug is compromised, we assessed the sterility and potency of medications commonly used in our obstetric anesthesia practice. Our goal was to evaluate the following drugs over a 30-day period: epinephrine, atropine, lidocaine, succinylcholine, and ephedrine. The medications were prepared by various medical staff, drawn into sterile plastic syringes and left at room temperature unprotected from light for the duration of the study. The syringes were collected daily, stored and randomly sampled after 7, 14, 21 and 30 days by research personnel. Potency and sterility of atropine, ephedrine and lidocaine were maintained over the study period. Succinylcholine and epinephrine could not be assayed but the solutions remained sterile for 30 and 14 days respectively. Data were incomplete for epinephrine. These findings suggest that some drugs that are commonly used in obstetric anesthesia are stable for long periods of time. Modification of current standards of practice could result in a significant reduction in drug waste and therefore cost.

Journal Article↗
PubMed2001

Genetic analysis of digestive physiology using fluorescent phospholipid reporters.

Zebrafish are a valuable model for mammalian lipid metabolism; larvae process lipids similarly through the intestine and hepatobiliary system and respond to drugs that block cholesterol synthesis in humans. After ingestion of fluorescently quenched phospholipids, endogenous lipase activity and rapid transport of cleavage products results in intense gall bladder fluorescence. Genetic screening identifies zebrafish mutants, such as fat free, that show normal digestive organ morphology but severely reduced phospholipid and cholesterol processing. Thus, fluorescent lipids provide a sensitive readout of lipid metabolism and are a powerful tool for identifying genes that mediate vertebrate digestive physiology.

Animals↗
PubMed2001

An outcomes analysis and satisfaction survey of 199 consecutive abdominoplasties.

Abdominoplasty is a popular body-contouring procedure. In this study the authors review retrospectively 199 abdominoplasty patients during a 15-year period to identify factors that affect overall outcome. Patients included 190 women and 9 men. The complication rate was 32% with few major complications (1.4%). The revision rate was 43%, and was related to fine-tuning the aesthetic appearance. Patients were divided into four groups based on tobacco use and history of diabetes and hypertension. There was no significant difference in revision rates or major complications between the subgroups. Minor complication rates, however, were significantly higher in smokers and patients with diabetes and/or hypertension. Complication and revision rates in patients undergoing intra-abdominal procedures combined with abdominoplasty were not significantly different from those patients undergoing abdominoplasty alone. A patient survey revealed symptom improvement in 95% of patients. Eighty-six percent of patients were satisfied with their result, and 86% would recommend abdominoplasty to a friend. The authors conclude that abdominoplasty is a safe and satisfying procedure, whether performed alone or in conjunction with another procedure. Patients are pleased with the outcome and have improvement in their symptoms, with minimal health risk. There is, however, a significant incidence of minor complications, related primarily to wound healing. These complications are increased significantly in smokers and patients with diabetes and/or hypertension. Revision rates are not different significantly between the subgroups. When complications do occur or revisions are required, they are minor and managed easily in an office setting.

Abdominal Muscles↗
PubMed2000

Effect of intravenous versus epidural fentanyl on the minimum local analgesic concentration of epidural bupivacaine in labor.

BACKGROUND: The minimum local analgesic concentration (MLAC) has been defined as the median effective local analgesic concentration (EC50) in a 20-ml volume for epidural analgesia in the first stage of labor. The aim of this study was to determine the relative local anesthetic sparing efficacies of intravenous and epidural fentanyl by comparison of their effects on the MLAC of bupivacaine. METHODS: In this double-blind, randomized, prospective study, 84 parturients at < or = 7-cm cervical dilation who requested epidural analgesia were allocated to one of two groups. After lumbar epidural catheter placement, 20 ml bupivacaine (n = 44) or bupivacaine with 3 microg/ml (60 microg) fentanyl (n = 40) was administered. The plain bupivacaine group then received 60 microg intravenous fentanyl. The bupivacaine-fentanyl group received intravenous saline. The concentration of bupivacaine was determined by the response of the previous patient in that group to a higher or lower concentration using up-down sequential allocation. Analgesic efficacy was assessed using 100-mm visual analog pain scores, with < or = 10 mm within 30 min define as effective. RESULTS: The MLAC of bupivacaine-intravenous fentanyl was 0.064% wt/vol (95% confidence interval, 0.049-0.080), and the MLAC of bupivacaine-epidural fentanyl was 0.034% wt/vol (95% confidence interval, 0.017-0.050). Epidural fentanyl significantly increased the analgesic potency of bupivacaine by a factor of 1.88 (95% confidence interval, 1.09-3.67) compared with intravenous fentanyl. The epidural fentanyl group demonstrated significantly higher dermatomal spread (P = 0.0064) and increased pruritus (P = 0. 01). CONCLUSIONS: Epidural fentanyl significantly reduced the MLAC of bupivacaine when compared with intravenous fentanyl for the parturients in this study. The significantly enhanced local anesthetic sparing, dermatomal level, and pruritus with epidural fentanyl suggest a primarily spinal site of action.

Adult↗
PubMed1999

Identification of a differentially expressed RNA helicase by gene trapping.

A mouse line was generated that expressed a gene trap reporter construct, betageo, in a dynamic pattern during embryonic development. Differential expression was seen within the developing eyes, limbs, heart, neural tube, and skeleton. Two transcripts were cloned that contained endogenous sequences fused to the gene trap vector sequence. Analysis of the endogenous sequences revealed that the reporter integrated within a gene belonging to a small group of eukaryotic superfamily I helicases. Unexpectedly, the majority of transcripts produced from the trapped locus were not affected by the insertion of the reporter. Although the function of the trapped helicase gene is unknown, its complex transcription patterns and widespread spatial-temporal distribution suggest that the gene product plays a role in RNA metabolism in multiple tissues and organs within the developing embryo.

Amino Acid Sequence↗
PubMed1999

Oral granisetron for strabismus surgery in children.

PURPOSE: To determine the efficacy of oral granisetron in preventing postoperative vomiting (POV) following strabismus repair in children. METHODS: In a randomized, double-blind, placebo-controlled trial, 73 pediatric patients received either placebo, 20 micrograms.kg-1 or 40 micrograms.kg-1 granisetron po 20 min before induction of anesthesia. No premedication was given, induction was with halothane and all children breathed spontaneously via a laryngeal mask airway. Maintenance was with isoflurane without the use of opioids. Ketorolac and acetaminophen were used for analgesia. The number of episodes and the severity of vomiting and retching were recorded for the first 24 hr postoperatively, as was the use of rescue antiemetics. RESULTS: Granisetron 20 micrograms.kg-1 and 40 micrograms.kg-1 were more effective than placebo in reducing the incidence of POV during the first 24 hr (29% in both the granisetron groups vs 84% in the placebo group, P < 0.05). In addition, the number of children experiencing severe vomiting (> or = 3 episodes) was reduced in the granisetron 20 micrograms.kg-1 and 40 micrograms.kg-1 groups compared with placebo (4%, 8% and 48% respectively, P < 0.05). Patients in the granisetron group were discharged home earlier (105 min vs 124 min, P = 0.04). There was no difference in the incidence of POV between the two granisetron groups. CONCLUSION: Preoperative oral granisetron in a dose of 20 micrograms.kg-1 provided effective prophylaxis against POV in children undergoing stabismus repair.

Acetaminophen↗
PubMed1999

Relative analgesic potencies of ropivacaine and bupivacaine for epidural analgesia in labor: implications for therapeutic indexes.

BACKGROUND: The minimum local analgesic concentration (MLAC) has been defined as the median effective local analgesic concentration in a 20-ml volume for epidural analgesia in the first stage of labor. The aim of this study was to assess the relative analgesic potencies of epidural bupivacaine and ropivacaine by determining their respective minimum local analgesic concentrations. METHODS: Seventy-three parturients at < or = 7 cm cervical dilation who requested epidural analgesia were allocated to one of two groups in this double-blinded, randomized, prospective study. After a lumbar epidural catheter was placed, 20 ml of the test solution was given, either ropivacaine (n = 34) or bupivacaine (n = 39). The concentration of local anesthetic was determined by the response of the previous patient in that group to a higher or lower concentration using up-down sequential allocation. Analgesic efficacy was assessed using 100-mm visual analog pain scores with < or = 10 mm within 30 min defined as effective. An effective result directed a 0.01% wt/vol decrement for the next patient. An ineffective result directed a 0.01% wt/vol increment. RESULTS: The minimum local analgesic concentration of ropivacaine was 0.111% wt/vol (95% confidence interval, 0.100-0.122), and the minimum local analgesic concentration of bupivacaine was 0.067% wt/vol (95% confidence interval, 0.052-0.082). Ropivacaine was significantly less potent than bupivacaine, with a potency ratio of 0.6 (95% confidence interval, 0.49-0.74). No difference in motor effects was observed. CONCLUSION: Ropivacaine was significantly less potent than bupivacaine for epidural analgesia in the first stage of labor.

Adult↗
PubMed1998

Expression of a gene trap reporter construct in a subset of cells in embryonic sites of hematopoiesis: evidence for alternative rRNA production in hematopoietic cells.

Three mouse lines were generated from independent gene trap events in embryonic stem cells. These lines express a betageo reporter gene in a subset of cells at sites of embryonic hematopoiesis. The 5' breakpoints of all three lines were found to lie in 45S ribosomal RNA transcription units. Expression was apparently linked to metabolic activity in these cells, since the kinetics of expression during embryogenesis matched that of cycling cells with colony forming unit spleen (CFU-S) potential. Expression was not seen in adult tissues unless the animals were treated with hydroxyurea, inducing synchronous entry of quiescent CFU-S into the cell cycle. Our results suggest that there is a subset of hematopoietic stem cells, which when actively proliferating, express the SAbetageo reporter construct from RNA polymerase I transcription units.

Animals↗
PubMed1998

Dose-dependent reduction of the minimum local analgesic concentration of bupivacaine by sufentanil for epidural analgesia in labor.

BACKGROUND: The minimum local analgesic concentration (MLAC) has been defined as the median effective local analgesic concentration in a 20-ml volume for epidural analgesia in the first stage of labor. The aim of this study was to determine the local anesthetic-sparing efficacy of epidural sufentanil by its effect on the MLAC of bupivacaine. METHODS: In this double-blind, randomized, prospective study, 147 parturients at < or = 7 cm cervical dilation who requested epidural analgesia were allocated to one of four study groups. After a lumbar epidural catheter was placed, study participants received 20 ml bupivacaine (n = 38), bupivacaine with sufentanil 0.5 microg/ml (n = 38), bupivacaine with sufentanil 1 microg/ml (n = 33), or bupivacaine with sufentanil 1.5 microg/ml (n = 38). The concentration of bupivacaine was determined by the response of the previous patient using up-down sequential allocation. The analgesic efficacy was assessed using 100-mm visual analog pain scores, with < or = 10 mm within 30 min defined as effective. RESULTS: The MLAC of bupivacaine alone was 0.104% wt/vol (95% CI, 0.090-0.117). The addition of sufentanil at doses of 0.5 microg/ml, 1 microg/ml, and 1.5 microg/ml resulted in significant reductions (P < 0.0001) in the MLAC of bupivacaine to 0.048% wt/vol (95% CI, 0.030- 0.065), 0.021% wt/vol (95% CI, 0-0.055), and 0.009% wt/vol (95% CI, 0-0.023), respectively. CONCLUSIONS: This study showed a significant (P < 0.0001) dose-dependent reduction in the MLAC ofbupivacaine by sufentanil.

Analgesia, Epidural↗
PubMed1998

Ratio encoding combinatorial libraries with stable isotopes and their utility in pharmaceutical research.

Combinatorial libraries are an important tool for lead discovery in the pharmaceutical industry. Advances in high throughput screening coupled with combinatorial chemistry can significantly reduce the time to find lead compounds. A major difficulty in developing large combinatorial libraries is the ability to identify active compounds. This paper describes a rapid and sensitive encoding/decoding methodology that utilizes stable isotopes and mass spectrometry. The ability of mass spectrometry to precisely determine the intensity of isotopic abundances provides a unique encoding strategy employing synthetically generated ratios of stable isotopes in a compound as the code. The application of ratio encoding is demonstrated using peptoid and imidazole chemistries. Supporting data demonstrate that the incorporation of one or more stable isotopes using unique-predetermined ratios can encode chemical libraries. In addition, the presence of a unique isotopic pattern in a ligand can facilitate the pharmacokinetic analysis. Isotope incorporation into a compound and subsequently into its metabolites reliably distinguishes products from other molecules in the mass spectrum. This is illustrated by metabolic analyses of peptoid and imidazole compounds.

Amino Acid Sequence↗
PubMed1997

Wild-type myoblasts rescue the ability of myogenin-null myoblasts to fuse in vivo.

Skeletal muscle is formed via a complex series of events during embryogenesis. These events include commitment of mesodermal precursor cells, cell migration, cell-cell recognition, fusion of myoblasts, activation of structural genes, and maturation. In mice lacking the bHLH transcription factor myogenin, myoblasts are specified and positioned correctly, but few fuse to form multinucleated fibers. This indicates that myogenin is critical for the fusion process and subsequent differentiation events of myogenesis. To further define the nature of the myogenic defects in myogenin-null mice, we investigated whether myogenin-null myoblasts are capable of fusing with wild-type myoblasts in vivo using chimeric mice containing mixtures of myogenin-null and wild-type cells. Chimeric embryos demonstrated that myogenin-null myoblasts readily fused in the presence of wild-type myoblasts. However, chimeric myofibers did not express wild-type levels of muscle-specific gene products, and myofibers with a high percentage of mutant nuclei appeared abnormal, suggesting that the wild-type nuclei could not fully rescue mutant nuclei in the myofibers. These data demonstrate that myoblast fusion can be uncoupled from complete myogenic differentiation and that myogenin regulates a specific subset of genes with diverse function. Thus, myogenin appears to control not only transcription of muscle structural genes but also the extracellular environment in which myoblast fusion takes place. We propose that myogenin regulates the expression of one or more extracellular or cell surface proteins required to initiate the muscle differentiation program.

Animals↗
PubMed1997

A multidimensional approach to protein characterization.

When mass spectrometry (MS) is used to study protein primary structure, it is used in a "static" mode. That is, the information is derived from a single MS or MS-MS spectrum. Information about more complex protein structure or protein interactions can also be gained via MS. If a series of mass spectra is collected as something else in the experiment is changing, we increase the "dimensionality" of the MS data. For example, measuring mass spectra as a function of time after exposure of a protein to deuterated solvents can provide information about protein structure. Likewise, by measuring mass spectra of a protein as the concentration of a binding ligand is changed, one can infer the stoichiometry of the complex. Another important, but fundamentally different way of increasing the dimensionality of mass spectral data is by coupling the mass spectrometer to a one- or two-dimensional separation technique.

Mass Spectrometry↗
PubMed1996

POU domain factor Brn-3b is required for the development of a large set of retinal ganglion cells.

The three members of the Brn-3 family of POU domain transcription factors are found in highly restricted sets of central nervous system neurons. Within the retina, these factors are present only within subsets of ganglion cells. We show here that in the developing mouse retina, Brn-3b protein is first observed in presumptive ganglion cell precursors as they begin to migrate from the zone of dividing neuroblasts to the future ganglion cell layer, and that targeted disruption of the Brn-3b gene leads in the homozygous state to a selective loss of 70% of retinal ganglion cells. In Brn-3b (-/-) mice other neurons within the retina and brain are minimally or not at all affected. These experiments indicate that Brn-3b plays an essential role in the development of specific ganglion cell types.

Animals↗
PubMed1996

Isotope or mass encoding of combinatorial libraries.

BACKGROUND: Combinatorial chemistry using solid-phase synthesis is a rapidly developing technology that can result in a significant reduction in the time required to find and optimize lead compounds. The application of this approach to traditional medicinal chemistry has led to the construction of libraries of small organic molecules on resin beads. A major difficulty in developing large combinatorial libraries is the lack of a facile encoding and decoding methodology to identify active compounds. RESULTS: Several encoding schemes are described which use the ability of mass spectrometry to ascertain isotopic distributions. Molecular tags are attached to resin beads in parallel or on the linker used for chemical library synthesis. The tags are encoded via a controlled ratio of a number of stable isotopes on the tagging molecules, and range from a single to a complex isotopic distribution. CONCLUSIONS: A novel coding scheme is described that is useful for the generation of large encoded combinatorial libraries. The code can be cleaved after assay and analyzed by mass spectrometry in an automated fashion. An important element of the combinatorial discovery process is the ability to extract the structure-activity relationship (SAR) information made available by library screening. The speed and sensitivity of the mass-encoding scheme has the potential to determine the full SAR for a given library.

Chemistry, Organic↗
PubMed1995

Rescue of early embryonic lethality in mdm2-deficient mice by deletion of p53.

The gene p53 encodes a transcriptional activator of genes involved in growth arrest, DNA repair and apoptosis. Loss of p53 function contributes to tumour development in vivo. The transcriptional activation function of p53 is inactivated by interaction with the mdm2 gene product. Amplification of mdm2 has been observed in 36% of human sarcomas, indicating that it may represent an alternative mechanism of preventing p53 function in tumour development. To study mdm2 function in vivo, we generated an mdm2 null allele by homologous recombination. Mdm2 null mice are not viable, and further analysis revealed embryonic lethality around implantation. To examine the importance of the interaction of MDM2 with p53 in vivo, we crossed mice heterozygous for mdm2 and p53 and obtained progeny homozygous for both p53 and mdm2 null alleles. Rescue of the mdm2-/- lethality in a p53 null background suggests that a critical in vivo function of MDM2 is the negative regulation of p53 activity.

Animals↗
PubMed1995

Self-association of a synthetic peptide from the N terminus of the hepatitis delta virus protein into an immunoreactive alpha-helical multimer.

The formation of hepatitis delta antigen (HDAg) multimers is required for full biologic activity of this protein and for replication of the hepatitis delta virus. To determine the residues responsible for multimerization, three peptides [ delta 12-49, delta 25-60(Y), delta 12-60(Y)] from the putative coiled-coil multimer-forming domain of HDAg were chemically synthesized and biophysically characterized by circular dichroic spectroscopy, deuterium-exchange mass spectrometry, gel filtration, chemical crosslinking, and ultracentrifugation. By circular dichroism the 50-residue peptide delta 12-60(Y) was half-denatured above 80 degrees C and was 97% alpha-helical at 5 degrees C and 84% alpha-helical at 37 degrees C. By deuterium exchange, peptide delta 12-60(Y) was 93% alpha-helical at 25 degrees C. Its high alpha-helicity and melting temperature are due to the formation of an alpha-helical multimer consisting of four or more chains. All three synthetic peptides reacted with human anti-HDAg antibodies in an enzyme-linked immunosorbent assay, but only peptide delta 12-60(Y) was detected in a sandwich radioimmunoassay in which successful antigens must display at least two antibody-binding sites, which correlates with the ability of this peptide to form multimers. Peptide delta 12-60(Y) also interfered with the self-association of natural HDAg into multimers. These results have significant practical implications for development of improved diagnostic tests, antiviral agents, and possibly even vaccines for prevention of hepatitis delta virus disease.

Amino Acid Sequence↗
PubMed1995

A single-bead decode strategy using electrospray ionization mass spectrometry and a new photolabile linker: 3-amino-3-(2-nitrophenyl)propionic acid.

A new linker that employs a photosensitive 3-amino-3-(2-nitrophenyl)propionyl functionality (ANP-resin) has been developed for the preparation of C-terminal carboxamides. A wide range of carboxamides were prepared and identified using the ANP-resin and electrospray ionization mass spectrometry. A single bead containing tripeptide Fmoc-Asp-Arg(Tos)-Val-NH2 was isolated, photocleaved and the peptide was characterized by tandem mass spectrometry, thereby verifying a library decode strategy that avoids complex tagging procedures.

Amino Acid Sequence↗