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Biomedical subjects

M Snyder

Publications and source records attributed to M Snyder.

At least 181 records · Page 10Linked to original sources
PubMed1987

Crosslinking of isolated cytoskeletal proteins with hemoglobin: a possible damage inflicted to the red cell membrane.

Crosslinking of isolated red cell membrane cytoskeletal proteins and hemoglobin mediated by H2O2 was studied. The products of spectrin and hemoglobin interaction were demonstrated electrophoretically to be high-molecular-weight polypeptides crosslinked by nondisulfide covalent bonds. The molecular weight of the protein bands correlated with various combinations of spectrin and hemoglobin chains and the relative amount of the different products was dependent on the molar ratio of the interacting proteins. Free hemin caused spectrin crosslinking as well, but globin in the absence of hemin was inactive. Since the H2O2-mediated reaction resulted in reduction of the spectrin tryptophan fluorescence, the latter was used to monitor the reaction progress under various conditions. Both oxyhemoglobin and methemoglobin were found to be most efficient, whereas cyanmethemoglobin and hemichrome were relatively inactive. Analysis of the data implied that tryptophan oxidation as well as spectrin conformational changes follow an iron-induced crosslinking of the interacting proteins. Actin, the second major protein in the red cell cytoskeleton, behaved similarly to spectrin. The intrinsic fluorescence intensity of both G- and F-actin was decreased upon addition of H2O2 to the mixture of hemoglobin and each of the actin forms. SDS-polyacrylamide gel electrophoresis revealed that G-actin crosslinked one or two hemoglobin chains. F-actin-hemoglobin interaction induced by H2O2 produced very high aggregates that could not penetrate the gel. It is suggested that crosslinking of cytoskeletal proteins in red cells containing membrane-associated hemoglobin provides a rationale for the loss of membrane flexibility.

Actins↗
PubMed1987

Atypical mitochondrial DNA from the deep-sea scallop Placopecten magellanicus.

The mitochondrial DNA of most metazoan animals is highly conserved in size, averaging about 17 kilobase paris (kbp). The mitochondrial DNA from the deep-sea scallop Placopecten magellanicus, in contrast, has been found to be approximately 34 kbp long. It is also highly variable in size from individual to individual and is unusual in the extent of its size variation. Mitochondrial DNAs from individuals collected at the same site differ by as much as 7 kbp. The size variation is due largely to differences in the number of copies of a tandemly repeated 1.2-kbp element.

Journal Article↗
PubMed1987

Analysis of immunoglobulin G antibody responses after administration of live and inactivated influenza A vaccine indicates that nasal wash immunoglobulin G is a transudate from serum.

Following intranasal administration of live influenza A virus vaccine or parenteral inoculation of inactivated influenza virus vaccine, immunoglobulin antibody to the influenza virus hemagglutinin was detected in nasal wash specimens from adult volunteers. Several observations supported the suggestion that this immunoglobulin G hemagglutinin nasal wash antibody appeared to be mainly derived from the serum by a process of passive transudation.

Adult↗
PubMed1986

The anatomical basis for retrorenal extensions of pancreatic effusions: the role of the renal fasciae.

Retrorenal extension of pancreatic inflammatory processes are considered to involve invasion of the posterior pararenal space. Analysis of computed tomographic (CT) images demonstrates preservation of posterior pararenal fat in most patients, implicating some other mechanism. We have examined the anatomical basis for these retrorenal extensions in static and functional studies of 12 cadavers using CT imaging, dissection and histological techniques. We observed that the posterior renal fascia was thicker than the anterior, that it could be easily separated into two layers by manual dissection and injections of liquid latex, that the inner (anterior) layer of the posterior fascia was continuous with the anterior fascia and the outer layer continuous with the lateroconal fascia. The point at which the two layers of the posterior fascia separated laterally and the medial extent of the posterior fascia varied considerably in CT scans of 100 patients. These data are interpreted to mean that pancreatic effusions extend posterior to the kidney by separating the two layers of the posterior renal fascia.

Fascia↗
PubMed1986

Rapid mapping of antigenic coding regions and constructing insertion mutations in yeast genes by mini-Tn10 "transplason" mutagenesis.

A "transplason" mutagenesis procedure was developed for the dual purposes of low resolution mapping of antigenic coding regions (using transposons) and constructing insertion mutations in yeast genes (by transplacement). Mini-Tn10 transposon derivatives containing both Escherichia coli and yeast selectable markers have been constructed. These elements are used to mutagenize lambda gt11 clones that express foreign antigens in E. coli. The transposition events are first selected in E. coli, and the effect of these insertions on antigen expression is used to locate the antigenic coding regions on the cloned DNA. Insertion mutations located within a desired yeast sequence are then substituted for the genomic copies by one-step gene transplacement. This provides a powerful method for rapidly mapping antigenic coding sequences of cloned genes and inactivating these genes in yeast to help determine their function. Several examples using this technique are presented.

Antibodies↗
PubMed1986

Stressor inventory for persons with epilepsy.

Persons who have epilepsy experience many stressors related to this chronic condition. Stressors arise both from the nature of the condition and from society's misconceptions and lack of knowledge about epilepsy. The specific stressors experienced and the salience of the stressors vary from individual to individual and over time. Existing stressor scales do not identify stressors specific to epileptic seizures. This article describes an instrument developed to assess stressors associated with epilepsy and its possible uses.

Adolescent↗
PubMed1986

Coordinate regulation of myelomonocytic phenotype by v-myb and v-myc.

Both avian myeloblastosis virus (by the action of v-myb) and avian myelocytomatosis virus MC29 (by the action of v-myc) transform cells of the myelomonocytic lineage. Whereas avian myeloblastosis virus elicits a relatively immature phenotype, cells transformed by MC29 resemble mature macrophages. When cells previously transformed by v-myb were superinfected with MC29, their phenotype was rapidly altered to that of a more mature cell. These superinfected cells expressed both v-myb (at a level similar to that found before superinfection) and v-myc. It therefore appears that the expression of v-myc can elicit certain properties of a more differentiated phenotype. In addition, unlike cells transformed by v-myb alone, the cells expressing both v-myb and v-myc could not be induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate to differentiate to fully mature macrophages. Cells with a morphology similar to that of the superinfected cells were elicited by simultaneously infecting yolk sac macrophages with avian myeloblastosis virus and MC29. Such cells expressed both v-myb and v-myc. These results indicate that expression of v-myb and v-myc in infected cells coordinately regulates myelomonocytic phenotype and that the two viral oncogenes vary in their ability to interfere with tumor promoter-induced differentiation. Our findings also sustain previous suggestions that the oncogenes v-myb and v-myc may not transform target cells by simply blocking differentiation.

Animals↗
PubMed1986

Renal fascial pathway: posterior extension of pancreatic effusions within the anterior pararenal space.

Retrorenal extension of pancreatic effusion or phlegmon associated with pancreatitis has been described frequently and is generally considered to represent extension of these processes from the anterior into the posterior pararenal space. A series of meticulous cadaveric dissections (n = 8) and a review of a large number of patients with pancreatitis (n = 53) show that these posterior collections actually represent extension of pancreatitis from the anterior pararenal space to a potential space between the laminae of the posterior renal fascia. Of 40 patients with posterior extension of pancreatic effusion or phlegmon, interfascial involvement was observed in all 40 and was bilateral in nine (23%). True involvement of the posterior pararenal space was uncommon, as was extension into the perirenal space. This phenomenon appears as a continuum of the well-described thickening of the renal fascia secondary to pancreatitis. It can be explained by new observations of the relationships between the fascia of Gerota and the lateroconal fascia.

Cadaver↗
PubMed1985

Isolation of the gene encoding yeast DNA polymerase I.

A yeast genomic DNA expression library in lambda gt11 antibody prepared against yeast DNA polymerase I were used to isolate the gene encoding DNA polymerase I. The identity of the DNA polymerase I gene was determined by several criteria. First, the clone-encoded protein is immunologically related to DNA polymerase I. Second, cells containing the gene cloned in the high copy number plasmid YEp24 overproduce the polymerase activity 4- to 5-fold as measured in yeast extracts. Finally, insertion of the gene downstream from a bacteriophage T7 promoter allows synthesis of yeast DNA polymerase I in Escherichia coli. Gene disruption and Southern hybridization experiments show that the polymerase is encoded by an essential, single copy gene. Examination of the germinated spores containing the disrupted gene reveals a defect in nuclear division and a terminal phenotype typical of replication mutants.

Cell Cycle↗
PubMed1985

Mitotic stability of yeast chromosomes: a colony color assay that measures nondisjunction and chromosome loss.

A colony color assay that measures chromosome stability is described and is used to study several parameters affecting the mitotic maintenance of yeast chromosomes, including ARS function, CEN function, and chromosome size. A cloned ochre-suppressing form of a tRNA gene, SUP11, serves as a marker on natural and in vitro-constructed chromosomes. In diploid strains homozygous for an ochre mutation in ade2, cells carrying no copies of the SUP11 gene are red, those carrying one copy are pink, and those carrying two or more copies are white. Thus, the degree of red sectoring in colonies reflects the frequency of mitotic chromosome loss. The assay also distinguishes between chromosome loss (1:0 segregation) and nondisjunction (2:0 segregation). The most dramatic effect on improving mitotic stability is caused by increasing chromosome size. Circular chromosomes increase in stability through a size range up to approximately 100 kb, but do not continue to be stabilized above this value. However, linear chromosomes continue to increase in mitotic stability throughout the size range tested (up to 137 kb). It is possible that the mitotic stability of linear chromosomes is proportional to chromosome length, up to a plateau value that has not yet been reached in our synthetic constructions.

Chromosomes↗
PubMed1985

Differential conduction of cold through barriers.

Despite the widespread use of ice packs in conjunction with ace bandages, padded ace bandages and compression dressings in the management of acute soft tissue trauma and sprains, the role of these barriers in the conduction of cold has not been adequately evaluated. Thermal probes were secured to both ankles of 62 healthy volunteers. The selected barrier was applied bilaterally and 500 g of chipped ice in a plastic bag was placed over the barrier on the right ankle for 30-45 minutes. A significant reduction in temperature of the right ankle was noted in all groups except in the padded ace group. The most rapid decrease in temperature was noted during the first 2 minutes of treatment. During the first minute, the surface temperature decreased an average of 22 degrees C (ace), 3.8 degrees C (dry washcloth), 5.2 degrees C (no barrier) and 5.4 degrees C (damp washcloth). After 10 minutes, the mean rate of cooling was 0.1-0.2 degree C and was approximately the same in all four groups. The Scheffe procedure indicated three homogeneous subgroups at 30 minutes: no barrier, damp washcloth; ace, dry washcloth; and padded ace. These findings question the clinical usefulness of the application of cold over padded aces and compression dressings and the use of a damp washcloth to 'protect' the skin from frostbite.

Bandages↗
PubMed1984

Ruptured corpus luteum with hemoperitoneum: a study of 173 surgical cases.

Ovarian hemorrhage from the corpus luteum of menstruation or pregnancy can be a life-threatening surgical condition which occurs at all stages of a woman's reproductive life. A corpus luteum cyst predisposes to rupture. There may be a delay of menses. Pregnancy increases the risk of rupture, and there is an increased risk of abortion and ectopic pregnancy. Most ruptures occur in the right ovary and can be misdiagnosed as appendicitis. Culdocentesis is positive for hemoperitoneum, and if the hematocrit is over 12%, surgical intervention is indicated for hemostasis. A tissue diagnosis should be made by cystectomy, luteectomy, or wedge excision.

Adolescent↗
PubMed1984

Progressive relaxation as a nursing intervention: an analysis.

Progressive relaxation is an intervention nurses have used during the past decade. Because nursing practice is seeking a more scientific basis for use of specific interventions, a review of studies that have used relaxation techniques is pertinent. In the 13 studies reviewed, the patient populations, purposes, procedures, measurements, and results are analyzed and compared. Points are provided for nurses to consider when selecting progressive relaxation as an intervention or carrying out research studies.

Adult↗