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Biomedical subjects

C Walker

Publications and source records attributed to C Walker.

At least 307 records · Page 17Linked to original sources
PubMed1989

A multicentre randomized trial comparing delivery with a silicone rubber cup and rigid metal vacuum extractor cups.

A total of 258 women requiring assisted delivery where vacuum extraction was thought to be suitable were randomly allocated to delivery with a new silicone rubber cup or metal vacuum extractor cups. There was a tendency for the silicone rubber cup to effect delivery more quickly and to cause less scalp trauma, but to fail to effect delivery on more occasions than metal cups. However, none of these differences was statistically significant. There were no statistically significant differences in the rates of birth canal trauma, maternal blood loss, or neonatal jaundice. The silicone rubber cup produced a cosmetically more acceptable chignon than the metal cups. The introduction of vacuum extractors with silicone rubber cups into obstetric units should be encouraged.

Double-Blind Method↗
PubMed1989

Use of art and play therapy in pediatric oncology.

Play enhances a child's physical growth and development and contributes to the mastery of language and social skills. It is essential for the child's psychological development and maturation. An overview of the field of play and art psychotherapy is presented with an outline of the function of play for the physically ill child. Techniques of play and art therapy that nurses can use for children with cancer, including therapeutic play, are described.

Art Therapy↗
PubMed1988

The superoxide generating system of B cell lines. Structural homology with the phagocytic oxidase and triggering via surface Ig.

EBV-transformed B lymphocyte cell lines (EBV-BLCL) produce superoxide after stimulation with phorbol ester, a capacity unique among nonmyeloid cells. The superoxide producing system of EBV-BLCL (B cell oxidase) was compared with the phagocytic NADPH-oxidase and the relationship of the capacity to produce superoxide to the presence of the EBV-genome was analyzed. The two EBV-transformed B cell lines F1 and HELL generated superoxide in response to PMA (2.3 nmol/10(6) F1 cells x 1 h and 6.27 nmol/10(6) HELL cells x 1 h with 1 microgram/ml of PMA), whereas no superoxide release was detected with the EBV-positive Burkitt lymphoma line WIL-2 and the EBV-negative plasmocytoma line U-266. Also, F1 and HELL showed lucigenin-dependent chemiluminescence (CL) after PMA-treatment, whereas no CL responses were detected from WIL-2 or U-266. Further, F1 and HELL cells contained a low potential cytochrome b-245 (10.9 and 61.0 pmol/mg protein, respectively) and also a 45 kDa diphenylene-iodonium (DPI)-binding peptide, both components of the phagocytic NADPH-oxidase. In contrast, neither the cytochrome b-245 nor the 45 kDa DPI-binding peptide were detected in WIL-2 and U-266. In addition, DPI inhibited O2- production by PMA-stimulated EBV-BLCL and polymorphonuclear granulocytes. Further, F1 line cells showed superoxide dismutase-inhibitable lucigenin-dependent CL when triggered by protein A-bearing staphylococci (Cowan strain I) or by a mAb directed against human IgG in the presence of solid-phase goat anti-mouse-Ig antibody. From a panel of eight EBV-BLCL, only five responded with CL when exposed to protein A-bearing staphylococci, whereas all showed CL when treated with phorbol ester. Inasmuch as all eight EBV-BLCL possessed surface Ig and a "functional" oxidase, their differential response to cross-linking of surface Ig may be determined by differences in signal transduction. Superoxide production by EBV-BLCL appears thus related to expression of an electron transport chain structurally homologous, if not identical, with the "phagocytic" NADPH-oxidase. Apparently, the presence of EBV-genome in B cell lines does not per se lead to expression of this oxidase. This suggests that nontransformed B cells may, at a certain differentiation stage, also express a superoxide-generating chain. From the finding of stimulation of superoxide production of EBV-BLCL via surface Ig it appears possible that also Ag may be able to trigger such B cells to production of superoxide which might have an important role in the physiology of B cells.

B-Lymphocytes↗
PubMed1988

Stimulation-dependent lymphokine mRNA levels in human mononuclear cells.

Steady-state mRNA levels for lymphokines were studied in human peripheral blood mononuclear cells stimulated by various agents. The pattern of mRNA levels differed according to the way in which cells were stimulated or activated. Stimulation by anti-CD3 antibodies led to increased mRNA levels for interferon-gamma but only extremely low levels of interleukin 2 mRNA were detected. In order to observe levels of interleukin 2 mRNA, it was necessary to use phorbol myristate acetate (PMA) in addition to either lectins or anti-CD3 antibodies. PMA by itself was already able to induce high levels of mRNA for granulocyte macrophage colony-stimulating factor. Most interestingly, different patterns of lymphokine production were obtained with stimuli yielding the same number of activated cells and the same ratio of activated CD4 and CD8 cells. Thus, different T cell stimuli induced distinct patterns of lymphokine mRNA levels.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1988

A neural degeneration mutation that spares primary neurons in the zebrafish.

We describe an embryonic lethal mutation in the zebrafish Brachydanio rerio that specifically affects the viability of most cells in the embryonic central nervous system (CNS). The mutation ned-1 (b39rl) was induced with gamma-irradiation and segregates as a single recessive allele closely linked to its centromere. It produces massive cell death in the CNS but a small set of specific neurons, including Rohon-Beard sensory neurons, large hindbrain interneurons, and primary motoneurons, survive embryogenesis and are functional. Synaptic connections between embryonic motoneurons and muscle cells appear physiologically normal, and the normally observed spontaneous flexions are present. Correlated with the presence of sensory neurons and interneurons, mutant embryos display reflexive movements in response to mechanical stimulation. Together, the surviving neurons, called primary neurons, form a class of cells that are prominent in size and arise early during development. Thus, this mutation may define a function that is differentially required by developmentally distinguishable sets of cells in the embryonic CNS.

Animals↗
PubMed1988

Maternally transmitted HIV infection in children.

We evaluated 16 children at high risk for AIDS because of mothers infected with HIV. Two children were persistently seropositive and had laboratory and clinical evidence of HIV infection but had no detectable infectious HIV in their peripheral blood mononuclear cells (PBMC). Seven children, all of whom had clinical and laboratory evidence of HIV infection, were seropositive and virus culture-positive. One child who died at 10 months of age of candida septicemia was HIV antibody-negative but HIV was grown from cultures of his PBMC. Six children had no serologic or virologic evidence of HIV infection; of these, four who were asymptomatic with normal laboratory studies were HIV antibody-positive up to 12 months of age but became antibody-negative by 15 months of age. These observations indicate that: (1) as many as 60% of infants of infected mothers may be infected with HIV; (2) maternal antibody can result in a false-positive or false-negative diagnosis of HIV infection in infants exposed in utero or perinatally, and (3) the use of viral cultures for HIV is valuable for the early diagnosis of maternally transmitted HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Outcome of children with hematologic malignancy who are admitted to an intensive care unit.

Sixty-four (48%) of 133 children with hematologic malignancy who were admitted to three pediatric ICUs died. Children who required management because of airway obstruction or after general anesthesia had the best outlook (mortality rate of 7% or less); those children who required major circulatory support or mechanical ventilation for hypoxemia did poorly (mortality rate of 84% or greater). Certain conditions in children with hematologic malignancy that require intensive care are associated with a mortality rate of approximately 75%. These include the following: suspected sepsis, interstitial pneumonitis, encephalopathy due to sepsis or hemorrhage. In children with these life-threatening conditions, therapy must be improved because at this stage, the patients do not benefit from admission to the ICU.

Anemia, Aplastic↗
PubMed1988

A case of cardiovascular collapse due to adrenal insufficiency.

A 6 year old boy presented with cardiogenic shock following a mild gastroenteritis-like illness. He was subsequently found to have adrenal failure secondary to adrenoleucodystrophy. Despite adequate corticosteroid replacement and intensive cardiorespiratory support, progressive cardiac failure occurred and the patient died. High levels of endogenous catecholamines may be toxic to the myocardium in the absence of sufficient corticosteroid.

Adrenoleukodystrophy↗
PubMed1988

Melbourne trial of adjuvant immunotherapy in operable large bowel cancer.

A controlled randomized clinical trial was undertaken to assess the ability of combined non-specific and specific immunotherapy to alter the disease-free interval and overall survival of patients with Stage B or C large bowel cancer. The immunotherapy consisted of a 2 year programme of vaccinations with BCG and neuraminidase-treated autologous tumour cells. Three hundred and one patients entered the trial. At 5 years of follow-up there is no evidence that this form of immunotherapy can alter either the disease-free interval or survival in this group of patients.

Antigens, Neoplasm↗
PubMed1988

Acute epiglottitis: a different approach to management.

Between January 1979 and October 1986, 349 patients with epiglottitis were admitted to the Royal Children's Hospital, Melbourne, Australia. Forty-five (13%) patients were not intubated, 291 (83%) were managed by nasotracheal intubation and spontaneous respiration without sedation, three (1%) received continuous positive airway pressure, and ten (3%) were ventilated. The 294 patients who were not ventilated were intubated for a mean of 18 +/- 9.5 (SD) h; 90% were extubated within 24 h. Criteria for extubation included resolution of fever (less than 37.5 degrees C), passage of time (12 to 16 h), and improvement in the general appearance of the child. Laryngoscopy was not performed before extubation. Providing there is always a doctor present who can reintubate if accidental extubation occurs, routine use of sedation, paralysis and mechanical ventilation, and pre-extubation laryngoscopy are not required for the management of children with uncomplicated epiglottitis, and their use may prolong the period of intubation.

Acute Disease↗
PubMed1987

Activation of T cells by cross-linking an anti-CD3 antibody with a second anti-T cell antibody: mechanism and subset-specific activation.

Binding of anti-CD3 antibody BMA030-F(ab')2 to T cells is not able to induce T cell proliferation even after additional cross-linking by plastic-bound goat anti-mouse Ig antibodies (panning) and addition of either interleukin (IL) 1 or IL2. In search for agents able to complement the signals provided by BMA030-F(ab')2, several antibodies directed against CD2, CD4, CD5, CD6 and CD8 were used. Neither of these caused T cell proliferation either by themselves or when simply added together with BMA030-F(ab')2. However, if BMA030-F(ab')2 and any other of these anti-CD2, CD4, CD5, CD6 or CD8 antibodies were cross-linked, then proliferation of T cells occurred. The mitogenic effect of cross-linking BMA030-F(ab')2 and a second anti-T cell antibody is dependent on the presence of monocytes or exogenously added IL2. The enhancing effect of monocytes could not be replaced by addition of IL1, suggesting that other soluble factors or monocyte contact might be involved in induction of activation signals. The mechanism leading to this mitogenic effect is dependent on combining cross-linking of BMA030 with the second anti-T cell antibody, whereby the second antibody appears to act as an "anchor" for the CD3 antibody, controlling and/or changing the signal transduction via the CD3 structure. This "anchor" hypothesis could be substantiated by the following observations: the best stimulatory signals were obtained at a BMA030/anti-T cell antibody ratio of 1:1; the effect is independent of the antibody isotype and the epitope recognized by the second antibody; the binding of BMA030 and separate cross-linking of the anti-T cell antibody was not sufficient to trigger T cell mitogenesis; immobilization by direct binding of the CD3 antibody alone or of the CD3 and second membrane structure/antibody complex separately was not sufficient to stimulate T cell proliferation. A further interesting aspect of this finding is the fact that a selective T cell stimulation is possible, since cross-linking BMA030-F(ab')2 plus anti-CD4 antibodies induced a selective stimulation of T4 cells, while cross-linking BMA030-F(ab')2 plus anti-CD8 activated solely T8 cells. It is thus possible to selectively activate T cell subsets in vitro.

Antibodies↗
PubMed1987

T cell activation by cross-linking anti-CD3 antibodies with second anti-T cell antibodies: dual antibody cross-linking mimics physical monocyte interaction.

The anti-CD3 antibody BMA030 (IgG2a isotype) induces T cell activation and proliferation if an interaction with monocytes is provided. In contrast to other anti-CD3 antibodies, it is unable to induce interleukin (IL)2 responsiveness through cross-linking by plastic-bound goat anti mouse Ig antibodies (panning). Cross-linking BMA030 with a second anti-T cell antibody is, however, able to induce IL 2 responsiveness in monocyte-depleted T cell cultures. In this report we show that a large number of different antibodies are suitable for this dual antibody stimulation, and that the extent of proliferation corresponds to the percentage of T cells expressing the respective T cell antigen. Proliferation induced by low concentrations (0.1-1 ng/ml) of other anti-CD3 antibodies requires also cross-linking with second anti-T cell antibodies. The proliferative response of monocyte-depleted T cells to two cross-linked anti-T cell antibodies plus added IL 2 is of the same magnitude as the one induced by anti-CD3 antibodies plus monocytes. On the other hand, if monocytes are present, soluble anti-CD2, -CD4, -CD8, -LFA-1 antibodies (IgG1 or F(ab')2 fragments) can inhibit OKT3 or BMA030-induced T cell activation. Anti-CD6 antibodies do not interfere with this monocyte-dependent T cell stimulation. We conclude that dual antibody stimulation mimics the physical contact of T cells with monocyte membranes, where the T cell receptor CD3 complex is cross-linked with neighboring structures (mainly so-called adhesion molecules) through the interaction with respective counter-structures on monocyte membranes. Dual antibody cross-linking bypasses this interaction and can be used to stimulate IL 2 responsiveness of antibody-defined T cells.

Adult↗
PubMed1987

Chlamydia trachomatis infection and pregnancy outcome.

Chlamydia trachomatis is now recognized as the most common sexually transmitted disease organism in the United States. Although the potential for vertical transmission of C. trachomatis from pregnant women to their infants is well established, the extent to which infection adversely affects pregnancy and causes perinatal complications remains controversial. We report herein the results of a prospective study of 270 pregnant women with endocervical C. trachomatis compared with 270 matched control subjects (age +/- 1 year, race, and socioeconomic status). Among the entire group (n = 540), the rates of pregnancy complications were: premature rupture of the membranes, 54/270 (10%); preterm delivery, 55 (11%); amnionitis, 20 (4%); intrapartum fever, 23 (4.3%); small for gestational age, 76 (14.5%); postpartum endometritis, 31 (6%); and neonatal sepsis, 10 (1.8%). No statistically significant differences were noted between cases and controls for any of these variables. In the subset of women with recent or invasive chlamydial infection, indicated by the presence of IgM antibody against C. trachomatis, preterm delivery occurred in 13/67 IgM-positive versus 8/99 IgM-negative (p = 0.03) cases. Premature rupture of the membranes was present in 13/67 IgM-positive versus 8/99 IgM-negative (p = 0.03).

Cervix Uteri↗