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Biomedical subjects

J Waddell

Publications and source records attributed to J Waddell.

At least 19 recordsLinked to original sources
PubMed2000

The effect of polyethylene particle chemistry on human monocyte-macrophage function in vitro.

Osteolysis remains the most important problem in orthopedic implant failure. Wear debris from the implant contains polyethylene (PE) particulate which has been shown to activate monocyte-derived macrophages (MDM). Although the response of MDM has been shown to be influenced by the size, shape, and chemical type of PE, the effect of chemically altered PE on MDM has not been studied. In this study, human MDM were seeded onto glass coverslips coated with virgin high density (HD)PE and chemically modified HDPE (impregnated with ppm levels of CoCl(2) and oxidized by heat) mixed with type I collagen and cultured for 96 h. Light microscopic evaluation demonstrated consistent phagocytosis of the HDPE particulate that was confirmed by scanning electron and transmission electron microscopy with little evidence of cytotoxicity. Evaluation of pro-inflammatory mediator secretion by MDMs in response to the virgin and chemically modified HDPE revealed significant differences in interleukin (IL)-1, tumor necrosis factor (TNF)-alpha, and IL-6 secretion. A significant elevation of IL-1 secretion was observed after initial exposure to virgin HDPE particles compared with controls (p = 0.001). IL-1 secretion was also elevated in the low oxidized particle groups (p = 0.001), whereas the highly oxidized particles were not different than controls. Secretion of both IL-6 (p = 0.03) and TNF-alpha (p = 0.007) were significantly elevated by the low oxidized HDPE particles whereas the virgin and highly oxidized groups showed no difference. The different effects on MDM activation when HDPE surface chemistry was altered, highlight the importance of defining the particle properties when studying the role of MDM activation in in vitro systems and extrapolating these observations to the in vivo situation.

Biocompatible Materials↗
PubMed1999

Effect of interleukin-6 secreted by engineered human stromal cells on osteoclasts in human bone.

The effect of elevated human IL-6 (hIL-6) production by human bone marrow (Hu-BM) stromal cells on osteoclasts in human bone was examined. Human bone was implanted into nonobese diabetic mice with severe combined immunodeficiency (Hu-Bone-NOD/SCID mice). Immunohistochemistry of bone implants and mouse spleens (at 20 weeks), showed human CD45+ cells, B cells, and macrophages in both tissues. Thus, Hu-BM cells survive human bone transplantation and infiltrate mouse tissue. Bone implants had 75 +/- 12% (mean +/- SD) human CD45+ cells, and 9 +/- 4% mouse hematopoietic cells. A retrovirus vector containing the human IL-6 gene was used to transduce Hu-BM stromal cells (IL-6/stromal) and the PA317 cell line (IL-6/PA317). IL-6/ stromal cells (secreting, on average, 17 microg of hIL-6/10(6) cells per 24 h) were injected directly into human bone implants in Hu-Bone-NOD/SCID mice. IL-6/PA317 cells (secreting 16 microg/mL of hIL-6/10(6) cells per 24 h) were injected intraperitoneally into Hu-Bone-NOD/SCID mice. Analyses of sera from both groups of animals showed elevated levels of IL-6. However, only bone implants engrafted with IL-6/stromal cells had a statistically significant increase in osteoclast-lined mineralized trabecular bone surface (BS). Thus, a high concentration of serum hIL-6 in Hu-Bone-NOD/SCID mice alone does not increase osteoclast-lined BS in bone implants. Most importantly, it is the type of human BM cell that secretes the high levels of hIL-6 that is most critical.

Animals↗
PubMed1997

Reducing the deleterious effects of intrauterine CO2 during fetoscopic surgery.

The fetoscopic approach to fetal intervention is a promising minimally invasive technique for correcting congenital anomalies in utero. However, expansion of the amniotic cavity with CO2 to visualize the fetus causes fetal hypercarbia and acidosis. We assessed whether maternal hyperventilation during intrauterine CO2 insufflation could attenuate the fetal hypercarbic acidosis. Seven fetal lambs of 105 +/- 2 days (mean +/- SEM) gestation (term = 145 days) were instrumented with a carotid arterial catheter in utero. After 7 +/- 1 days of recovery, fetoscopic exposure was obtained with intrauterine insufflation of CO2 at 10 mmHg of intraamniotic pressure. After 30 min, the ewe was hyperventilated at a mean respiratory rate of 23/min for 30 min under continuous insufflation. The uterus was then deflated and following 1 hr of stabilization, and the same protocol of CO2 pneumometrium was repeated. Fetal and maternal arterial blood was sampled at baseline and at 15 min intervals. Fetal PaCO2 increased during 30 min of CO2 insufflation (50.8 +/- 2.8 vs. 72.3 +/- 5.0 mmHg, P < 0.01); however, this change was reversed (to 51.5 +/- 3.0 mmHg, P < 0.01) by 30 min of maternal hyperventilation. The fetus developed acidosis after 30 min of CO2 pneumometrium (pH 7.350 +/- 0.012 vs. 7.236 +/- 0.026, P < 0.01); this was also reversed (to 7.366 +/- 0.019, P < 0.01) by maternal hyperventilation. These results were reproducible during the second CO2 insufflation challenge. Fetal hypercarbic acidosis during fetoscopy with CO2 insufflation is reduced by maternal hyperventilation.

Acidosis↗
PubMed1997

Hemodynamic alteration by fetal surgery accelerates myocyte proliferation in fetal guinea pig hearts.

BACKGROUND: Fetal heart development occurs by hyperplasia as myocytes lose the capacity to proliferate at birth. This potential for cell division may have application in altering fetal growth patterns in congenital cardiac malformations, but it is not known whether the proliferative activity can be modified by intrauterine surgical manipulation. The purpose of this study was to determine whether hemodynamic alteration by fetal surgery influences myocyte proliferation and myocardial development. METHODS: Six pregnant guinea pigs of 50 to 52 days of gestation (term, 65 days) underwent hysterotomy, and the fetal ascending aorta was banded and narrowed by 50% (AoB). Cesarean section was performed near term, and the heart was assessed for myocyte proliferative activity (Ki-67 monoclonal antibody), apoptosis, and morphologic features. RESULTS: The heart to body weight ratio (1.02% +/- 0.12% versus 0.42% +/- 0.02%, p < 0.01) and left ventricular posterior wall thickness (1.89 +/- 0.25 mm versus 1.31 +/- 0.19 mm, p < 0.01) were significantly higher in the AoB group. The percentage of Ki-67 positive cells was increased in AoB group (29.5% +/- 4.4% versus 15.3% +/- 1.3% in right ventricle, 35.8% +/- 5.1% versus 13.1% +/- 1.7% in interventricular septum, and 39.8% +/- 3.2% versus 12.0% +/- 2.0% in left ventricle (p < 0.01). The apoptotic cell to myocyte ratio was less than 1/1000 in both groups. CONCLUSIONS: Fetal hemodynamic alteration by aortic banding accelerates myocardial cellular proliferation without affecting apoptosis, suggesting that in utero cardiac interventions have a greater influence on myocardial development compared with postnatal intervention.

Animals↗
PubMed1997

The nurse manager as career coach.

The conventional wisdom has been that career coaching is an important part of the nurse manager's role. In the current stressful healthcare environment, nurse managers seem more than ever in need of direction in this area. This paper examines the nurse manager's traditional role as a career coach, identifies the problems the current environment poses for implementation of that role and, considers options for achieving the goal of supporting staff with career development.

Career Mobility↗
PubMed1994

Evidence that increases in lymphocyte tyrosine phosphorylation precede cardiac allograft rejection. Effects of cyclosporine and potential use in clinical management.

Tyrosine phosphorylation is an early, critical event in lymphocyte signal transduction. We measured tyrosine phosphorylation in a porcine experimental transplant model to evaluate its utility in monitoring the allograft immune response. Using flow cytometry, we demonstrate a biphasic increase in phosphotyrosine (ptyr) levels in peripheral blood mononuclear cells (PBMC), and that increases are detectable as early as 1 day posttransplantation in untreated transplanted animals (n = 4). This biphasic response is likely result from the sequestration of ptyr+ cells from the periphery into the graft as graft-infiltrating lymphocytic cells show increased ptyr levels. This suggests possible lymphocyte trafficking between the peripheral compartment and the allograft. A 5-day course of treatment with cyclosporine (CsA) at 20 mg/kg/day (n = 4), but not at 10 mg/kg/day (n = 4), prevents graft rejection in this allograft model. Strikingly, treatment with 20 mg/kg/day CsA, but not with 10 mg/kg/day, suppressed increases in ptyr levels in both PBMC and graft-infiltrating cells. Increases in ptyr levels in PBMC are detectable 2-5 days before histologic and electrocardiographic signs of graft rejection, suggesting a potential diagnostic utility for measuring tyrosine phosphorylation in monitoring and managing transplant rejection.

Animals↗
PubMed1993

Non-Hodgkin's lymphoma: an unusual cause of myocardial infarction and hypercalcaemia.

Cardiac involvement is reported in 10%-20% of patients with lymphoma, but it is characteristically difficult to detect clinically or by investigation. Hypercalcaemia is a rare complication. Both complications usually occur late in the natural history of lymphoma. We report a case of non-Hodgkin's lymphoma, who, within 2 weeks of presentation, developed symptomatic hypercalcaemia and, 3 days later, died of an acute myocardial infarction. Autopsy showed, unexpectedly, the unusual finding of coronary artery compression by lymphomatous deposits.

Aged↗
PubMed1990

Occupational stress and coping strategies among female baccalaureate nursing faculty.

Considerable stress is involved in nursing education. However, the sources and extent have not been fully investigated, nor have ways of coping. The main purpose of the study was to explore the sources and levels of perceived stress, coping strategies and effectiveness among female baccalaureate nursing faculty. The second purpose was to examine the relationship between stress, coping and academic responsibilities of the faculty member such as teaching, research and community service. A sample of 70 subjects from eight Ontario universities completed the demographic questionnaire, the researcher-developed 'Stress-Coping Anxiety Inventory', and the 'State-Trait Anxiety Inventory' Form Y (STAI) (Spielberger et al. 1983). Analysis of data using frequencies, cross tabulations, ANOVA and Pearson product-moment correlation were computed. Perceived stressors chosen most frequently as high in stress (greater than or equal to 4) (range = 1-5), in rank order, were 'heavy workload (combined clinical and classroom teaching)', 'retaining failing students', 'failing clinically unsatisfactory students', 'meeting research requirements' and 'providing individual clinical supervision'. Active coping strategies were selected more frequently as being effective (greater than or equal to 4) than passive coping strategies. Age of the respondent, number of years of full-time teaching and tenure status were most often significant factors (less than 0.05) relating to the level of stress. Implications for nursing education administrators and their faculty are discussed.

Adaptation, Psychological↗
PubMed1989

The effects of motion on the healing of cancellous bone.

In 20 dogs olecranon osteotomies fixed with tension band wires were studied histologically to reveal the pattern of healing. Different degrees of stability existed in different areas of the osteotomy. Under stable conditions cancellous bone healed by direct formation of woven bone. Instability resulted in an internal cartilaginous callus. Once stability was restored, the callus underwent endochondral ossification. The articular defect, which was in an area of maximum instability, healed by fibrocartilage.

Animals↗
PubMed1984

Electron microscopic localization of the chloroplast DNA replicative origins in Chlamydomonas reinhardii.

Chloroplast DNA, isolated from a synchronized culture of Chlamydomonas reinhardii, was digested with restriction endonucleases and examined in the electron microscope. Restriction fragments containing displacement loops (D-loop) were photographed and measured to determine the position of replicated sequences in relation to the restriction enzyme sites. D-loops were located at two positions on the physical map of chloroplast DNA. One replication origin was mapped at about 10 kb upstream of the 5' end of a 16s rRNA gene. The second origin was spaced 6. 5kb apart from the first origin and was about 16.5 kb upstream of the same 16s rRNA. Initiations at those two sites were not always synchronized. Replication initiated with the formation of a D-loop resulting from the synthesis of one daughter strand. After a short initial lag phase, corresponding to the synthesis of 350 +/- 130 bp of one daughter strand, DNA synthesis then proceeded in both directions. Both D-loop regions were preferred binding sites of undetermined protein complexes.

Base Sequence↗
PubMed1984

Cloning and delimiting one chloroplast DNA replicative origin of Chlamydomonas.

The EcoR1 restriction fragments containing D-loops which marked the replication origin of chloroplast DNA were identified in two different species of Chlamydomonas. Each fragment was cloned in the E. coli plasmid pBR325. The cloned fragments were compared by restriction endonuclease analyses and by heteroduplex analyses in the electron microscope. The relative position of the D-loop regions and the homologous regions between the 2 fragments was determined. The D-loops were located within one short homologous region of 0. 42kb in length between the 2 cloned restriction fragments. The homologous region was subcloned in pBR322. Closed circular plasmid DNAs containing the short homologous region showed preferred denaturation in the D-loop region under physiological salt concentration which suggested that D-loop region was AT rich. Sequence divergence was detected at both ends of the D-loop region. Southern blot analyses indicated the presence of species-specific repetitive sequences within the divergent regions.

Base Sequence↗
PubMed1982

Transmission electron microscopic study of polytene chromosome 2R from Drosophila melanogaster.

A simple and rapid method for studying polytene chromosome squashes by transmission electron microscope (TEM) is described. This technique provides close correlation between the light microscopic image and the TEM image. Fine structures of the chromosomes are preserved. The band pattern of region 44 A to 50 F of the chromosome 2 R has been analyzed and compared with Bridges' map (1935) and Lefevre's photographic representation (1976).

Animals↗
PubMed1977

Thermal data from helicopters operating in a sub-arctic environment.

Using automatic and observer-operated equipment for monitoring thermal data, observations have been made during Royal Navy Wessex 5 helicopter operations in a sub-Arctic climate. Measurements were taken in flight of front and rear cabin temperatures and aircrew deep body and skin temperatures. The results indicate that the "arcticised" aircraft used had more than enough cabin heating to alleviate cold stress on the aircrew.

Aerospace Medicine↗
PubMed1976

The below-the-knee amputation for vascular disease.

Of 190 consecutive patients with below-the-knee amputation done for diabetic or arteriosclerotic vascular disease, 167 were successfully fitted with a prosthesis and used the prosthesis in some or all of the activities of daily living. The surgical failure rate was 4.2 per cent; only eight patients required surgical revision to a higher level of amputation. The technique of rigid plaster dressing followed by delayed application of a plaster cast and pylon was not detrimental to wound healing and did not increase the interval between surgery and the use of the prosthesis, nor did it depress the eventual level of function. When compared with our own previous experience with other flaps, the long posterior flap offered a significant advantage in healing rate.

Amputation, Surgical↗