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Biomedical subjects

D Ward

Publications and source records attributed to D Ward.

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

A novel bioassay to predict the clinical response to cryofiltration treatment. A preliminary report.

Phagocytosis by normal human mononuclear monocytes grown in vitro was examined after incubation with known concentrations of aggregated human gamma-globulin (AHG) and in plasma obtained from patients suffering from immunologic diseases. When the phagocytes were pretreated with AHG, an inverse relationship between amounts of AHG and phagocytosis of radiolabeled Candida albicans was found. Inhibition of phagocytosis by patient plasma was independent of other laboratory determinations including antinuclear antibody, C3, C4, CH50, DNA-binding and circulating immune complexes. Plasma from 5 patients subjected to cryofiltration treatment (CFT) demonstrated less inhibition after than before CFT. This lessened inhibition of phagocytosis in vitro correlated with the clinical response due to CFT. The response to CFT could not be predicted by the conventional laboratory parameters investigated. Improvement between pre- and post-CFT plasma estimated by using the present bioassay may provide a quantitative description of which patient may benefit from plasmapheresis treatment procedures.

Biological Assay↗
PubMed1986

Gas transfer in microgravity fermentations.

Fermentations performed under microgravity conditions may be used in future long duration space missions for recycling expendable life support materials. These fermentations will differ from similar fermentations performed at one gravity in the manner in which gas transfer in the fermentor is carried out.

Biomass↗
PubMed1986

The efficacy of 5-fluorouracil, mitomycin C, and methyl CCNU in advanced colorectal cancer.

Sixty-six patients with advanced colorectal cancer were treated with 5-fluorouracil, Mitomycin C, and 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea. Fifty-seven patients were evaluable by completing 2 months of therapy. Nine patients (16.0%) achieved a complete remission (CR) with the above combination. A partial remission (PR) was seen in 9 patients. The response rate (CR + PR) was 32%. The average duration of response was 8.5 months. Mucositis, leukopenia, and thrombocytopenia were the significant toxicities experienced in this study.

Adult↗
PubMed1986

Bipolar coagulation in microvascular surgery.

In microvascular surgery and surgery of the hand, hemostasis must be accomplished very precisely to avoid injury to adjacent structures. Bipolar coagulation is one of the more precise techniques, since theoretically, current flows only through tissue that is held between the tips of the forceps. Experiments were done in rats to confirm that bipolar coagulation can be used to control vessel branches without disturbing the parent vessel or adversely affecting an adjacent anastomosis. However, the importance of the characteristics of the bipolar generator require particular attention. The generator used in these experiments produces a continuous-sine-wave current to minimize voltage. In addition, the equipment was designed to sense impedance and to automatically shut down at the point of desiccation, thus avoiding sparking, charring, and adherence of tissue to the forceps.

Abdomen↗
PubMed1986

Release of eicosanoids from white blood cells, platelets, smooth muscle cells, and endothelial cells in response to endotoxin and A23187.

Endotoxin produces numerous pathophysiologic changes in animals, including vascular endothelial cell damage and hematologic changes. Direct effects of endotoxin on arachidonic acid metabolism and the release of eicosanoids from endothelial cells and neutrophils have been reported. A rapid release of these autocoids occurs when cells are incubated with endotoxin, and this appears to be one of the earliest endotoxin-induced changes. Some of these eicosanoids may result in beneficial effects, and others may result in detrimental effects. This study was to determine the release of eicosanoids from white blood cells, platelets, smooth muscle cells, and endothelial cells in response to varying amounts of endotoxin and the calcium ionophore A23187. The results indicate that endotoxin has a major direct effect on vascular endothelial cells and smooth muscle cells as indicated by its ability to increase the synthesis of predominately i6-keto-PGF1 alpha by these cells. These effects were seen within a dose range of endotoxin that is lethal in horses. Very high concentrations of endotoxin (100 micrograms/ml) were required to stimulate a small increase in the production of i6-keto-PGF1 alpha and iLTC4 by freshly isolated neutrophils. Stimulation of cells with A23187 revealed that, of the eicosanoids measured, the one produced predominately by endothelial cells and smooth muscle cells was 6-keto-PGF1 alpha, by platelets was TxB2, and by neutrophils was LTC4 (LTB4 was not measured). A mixture of all white blood cells including platelets when incubated with A23187 produced large amounts of TxB2, LTB4, and LTC4 with smaller amounts of 6-keto-PGF1 alpha. The results indicate that endotoxin directly affects cells and stimulates them to produce thromboxane and prostacyclin, but very high concentrations of endotoxin were required to stimulate neutrophils to produce rather small increases in iLTC4.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Television and violent criminal behavior: beyond the Bobo doll.

This study builds on the research concerning television viewing and aggression by extending the external validity, or generalizability, of the dependent variable. We assess the relationship between self-reported television viewing at 8, 10, and 12 years of age and the subsequent commission of a violent criminal act. This study is based on interview data from 48 males incarcerated for violent crimes and 45 nonincarcerated, nonviolent males matched on age, race, and neighborhood of residence during adolescence. Results show that the extent of a respondent's reported television viewing was not, in and of itself, predictive of violent criminal acts. Instead, it was the interaction of heavy doses of television viewing and exposure to either maternal or paternal abuse that related to violent crime. These findings support the efforts of some recent scholars in their attempts to understand why television has a negative effect on only some viewers. The results are discussed in light of the cognitive formulations of neoassociationism, encoding specificity, and the double-dose effect.

Adolescent↗
PubMed1985

Misdiagnosis of chronic recurrent ventricular tachycardia.

24 patients with recurrent ventricular tachycardia were repeatedly misdiagnosed as having supraventricular tachycardia. Supraventricular tachycardia was recorded as the diagnosis 163 times in these patients. 72 12-lead electrocardiograms (ECGs) were available and they were reviewed together with the notes made at the time of the ECGs to discover the reasons for misdiagnosis. 7 consultant cardiologists, 22 consultant physicians, 13 senior registrars, and 57 registrars were involved in the misdiagnosis. Retrospective application of the established criteria used to distinguish ventricular tachycardia from supraventricular tachycardia with aberrancy enabled the diagnosis of ventricular tachycardia to be made in 22/24 patients (92%). In all but 2/72 episodes the only differentiating criterion noted by the attending physicians was dissociated atrial activity, and there seemed to be considerable bias in favour of the diagnosis of supraventricular tachycardia. 20/24 patients were given inappropriate treatment, which had dangerous consequences in 5.

Adolescent↗
PubMed1984

Ventricular pre-excitation.

Pilots and new applicants with asymptomatic 'safe' WPW syndrome should be allowed to fly but not as pilot in sole command. Professional pilots with tachyarrhythmia related to a pre-excitation syndrome should usually be disqualified . Personnel who have undergone successful surgical treatment by ablation of an accessory pathway could be considered for recertification to fly but drug therapy is at present unacceptable.

Aerospace Medicine↗
PubMed1983

Spontaneous manifestation of dual AV nodal pathways resulting in complex patterns of AV conduction.

Dual intranodal pathways are not uncommonly demonstrated at electophysiological study especially in patients with intranodal re-entrant tachycardias. This type of tachycardia is the most common spontaneous manifestation (albeit indirect) of dual AV nodal pathways. Other forms of spontaneous expression of dual atrio-His conduction are rare. In this report we describe a patient who exhibited complex atrioventricular conduction patterns over two intranodal pathways.

Adult↗
PubMed1982

Ten-year experience of 359 epicardial pacemaker systems: complications and results.

In the last ten years (1970-1980) 457 patients underwent permanent pacemaker insertion in the Brompton Hospital. Our practice has been somewhat atypical in that the majority of these patients had epicardial leads, initially using a Cordis intramural sutured electrode (85 patients), and subsequently a Medtronic sutureless electrode (274 patients). Our initial experience with these electrodes was satisfactory, but more recently it has become apparent that the long-term morbidity and complication rate is high. The respective complication rates being 25% and 18% for sutured and sutureless epicardial electrodes. In this study, lead complications were defined as those requiring lead replacement, and problems most commonly encountered were high voltage threshold, infection, and lead fracture. Unless there are specific indications for epicardial pacing it is now our policy to treat patients requiring permanent pacing with endocardial systems. Our complication rate with this technique (90 patients) is significantly lower (9%).

Adolescent↗
PubMed1982

Nonspecific protease and elastase activities in rat leukocytes.

Extracts were prepared from rat peritoneal leukocytes obtained 4 h after glycogen injection and assayed for proteolytic enzyme activities against various substrates. The substrates used included acid-denatured bovine hemoglobin, bovine serum albumin, a partially purified preparation of rat pulmonary basement membrane, bovine neck ligament elastin, and an artificial substrate with elastase specificity. A high level of activity was observed when hemoglobin was used as the substrate. The serum albumin and basement membrane preparation were also readily hydrolyzed by the leukocyte extract. In contrast, the native elastin and synthetic elastase substrate were much more resistant. Although the leukocyte extract demonstrated little intrinsic elastase activity, when it was mixed with a commercial hog pancreatic elastase preparation, it greatly potentiated the elastolytic activity, suggesting the activation of a latent enzyme.

Animals↗
PubMed1982

Rate-related accelerating (autodecremental) atrial pacing for reversion of paroxysmal supraventricular tachycardia.

Twenty consecutive patients with paroxysmal intra A-V nodal or atrio-ventricular tachycardia had a new tachycardia reversion pacing modality evaluated during routine electrophysiological study. The pacing was controlled by a micropressor interfaced with a stimulator connected to a right atrial pacing electrode. On detection of tachycardia the first pacing cycle interval is equal to the tachycardia cycle length minus a decrement value D. Each subsequent pacing cycle is further reduced by the same value of D, thus accelerating the pacing burst until a plateau of 100 beats/min faster than tachycardia (with an absolute lower limit of 275 beats/min) is reached. Seven different values of D (2, 4, 8, 16, 24, 34, 50 msec) were assessed in combination with three different durations of pacing P (500, 5000 msec). With P:500, only 2/20 tachycardias were terminated, but with P:1000, 16/20 were terminated. With P:5000 all were terminated and the combination successful in all patients was P:5000 and D:16. No unwanted arrhythmias were induced. In contrast, competitive constant rate overdrive atrial pacing accomplished tachycardia termination in all cases, but in four instances resulted in atrial flutter or fibrillation. Autodecremental pacing, which tends to avoid stimulation in the vulnerable period, allowed safe and successful termination of all tachycardias evaluated in this study.

Atrial Fibrillation↗