Biomedical subjects
Publications and source records attributed to L Preston.
In the outside world, children with serious skin conditions often face isolation and loneliness. Their peers give them nicknames, uninformed adults ask difficult questions. Once they get to Camp Horizon, however, they forget their disease, and swim, boat, stargaze, sing around the fire. They meet other children just like themselves. According to one boy, 'This place is like Heaven on Earth for me."
Two interactive virtual reality environments were used to identify factors that may affect, or be affected by, the degree of immersion in a virtual world. In particular, the level of stress in a "swimming with dolphins" simulation is measured, as is the degree of simulator sickness resulting form a virtual roller coaster. Analysis of the results indicates that a relationship between the degree of immersion and the following factors: excitement, comfort, quality and age. The following factors are found to depend on the degree of immersion: simulator sickness, control, excitement and desire to repeat the experience.
In order to facilitate the identification of human haemopoietic growth factors (HGFs), in complex conditioned media from limited cell sources, we have developed a method for the rapid assay of HGFs using bone marrow stem cells (BMSCs) obtained by Percoll density gradient enrichment of non-adherent cells from long-term human bone marrow culture. These BMSCs provide the basis for a 72 h assay where proliferation is triggered by the presence of GM-CSF, G-CSF and IL-3. The assay is up to 1000 times more sensitive than the conventional colony assay in detecting the presence of HGFs. We also describe methods for the rapid separation and identification of HGFs using fast protein liquid chromatography (FPLC) with phenyl-Superose and Mono Q columns. This enables individual HGFs present in complex conditioned media to be rapidly identified from the elution profile of HGF activity determined in the BMSC assay.
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Of 1265 patients admitted to the CCU with the diagnosis of acute MI, 96 (7.6%) developed ventricular fibrillation within 72 hours following admission. Of these 96, 35 (36.5%) had secondary VF associated with left ventricular failure; they had a high in-hospital mortality of 57.1%. The remaining 61 (63.5%) had primary VF, i.e. VF occurring in the absence of significant LV failure. Fourteen of these (23%) died in hospital: 9 due to PVF (3 during the first episode, 6 during a recurrence). This mortality figure was significantly higher (P less than 0.001) than the mortality of 10% seen among patients who did not experience VF. Primary VF showed a recurrence rate of 20%. Compared with the 1061 patients who left the hospital without primary VF, the 61 subjects with this rhythm disorder were older, had larger infarcts and more frequent complications, such as pericarditis, conduction abnormalities, frequent ventricular premature contractions and signs of right ventricular failure. These findings, in contrast with a widely held view, suggest that primary VF may carry a guarded prognosis.
An early pericardial friction rub was noted in 23.4% of a population of 1264 consecutive patients admitted with acute myocardial infarction. The incidence of the rub did not vary with age, sex or past cardiac history. The pericardial rub, however, was more often a complication of Q- than non-Q-wave infarcts (25.5% vs 10.5%, P greater than 0.001) and of anterior than inferior infarcts (35.3% vs 20.8%, P greater than 0.001). In comparing the 297 patients with a pericardial rub to the 967 others, we noted that the former group had a higher CK peak (1706 +/- 1110 UI l-1 vs 1189 +/- 1038 UI l-1, P greater than 0.001) and a higher incidence of Killip class greater than 1 (47.5% vs 33.2%, P greater than 0.001), atrial flutter or fibrillation (22.2% vs 9.3%, P greater than 0.001), second or third degree atrioventricular blocks (16.8% vs 9.4%, P greater than 0.001) and complete bundle branch block (14.5% vs 7.1%, P greater than 0.001). In spite of this, the development of a pericardial rub did not increase the in-hospital mortality (10.8% in patients with pericardial rub; 11.3% in those without).
We have utilized digitized video microscopy to investigate the influence of verapamil, a calcium channel blocker, on the in vitro effects of daunomycin in P388 sensitive and resistant sublines. In this study, verapamil enhanced the uptake of daunomycin and its cytotoxicity in both sublines, but the effect was more pronounced in the resistant cells. Flow cytometry showed a pronounced accumulation of resistant cells at G2-M when treated with daunomycin in the presence of verapamil, with no effects observed in the absence of verapamil. Analysis of individual resistant cells using the digitized video fluorescence microscopy technique demonstrated that the influence of verapamil on daunomycin uptake affected all cells and was not restricted to certain subpopulations of cells.
We have investigated the in vitro drug-cell interaction and therapeutic effects of a low-density lipoprotein (LDL)-daunomycin complex as compared to free daunomycin. Uptake and retention of daunomycin were significantly enhanced in sensitive and resistant P388 leukemia cells when they were perfused with LDL-daunomycin complex relative to free drug. The interaction of the LDL-daunomycin complex with P388 cells appeared to be through a LDL-specific pathway since competition with free LDL but not high-density lipoprotein significantly reduced daunomycin uptake. The LDL-daunomycin complex was cytotoxic to both daunomycin-sensitive and daunomycin-resistant P388 sublines. Colony growth studies showed the LDL-daunomycin complex to be more cytotoxic at shorter exposure times relative to free drug. Resistant cells showed 55 and 12% colony growth with 10-min and 2-hr exposures, respectively, to 0.4 microgram daunomycin/ml of the LDL-daunomycin complex. Free drug at 0.4 microgram/ml drug concentration and similar exposure times resulted in no loss in colony growth. The resistant cells were subjected to cell cycle analysis based on DNA content and showed an accumulation of cells at the G2-M phase of the cell cycle when treated with the LDL-daunomycin complex, with no effects being observed with free daunomycin.
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