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Biomedical subjects

R Stone

Publications and source records attributed to R Stone.

At least 91 records · Page 5Linked to original sources
PubMed1995

The tar reduction study: randomised trial of the effect of cigarette tar yield reduction on compensatory smoking.

BACKGROUND: Observational and short term intervention studies have reported that smokers of low tar cigarettes inhale more deeply (that is, compensate) than those who smoke high tar cigarettes. To quantify this effect a long term randomised trial was conducted on the effects of switching to low tar cigarettes. METHODS: The trial was carried out between April 1985 and March 1988 among cigarette smokers in the British Civil Service, measuring blood carboxyhaemoglobin (COHb) levels and serum cotinine levels as markers of tobacco smoke intake. Volunteers first switched to a cigarette brand yielding around 10% less tar than their usual brand to identify smokers able to change brand. The 434 subjects who successfully switched were then randomly allocated to one of three groups: (a) "fast reduction" group which changed to a brand of cigarettes with a tar yield of about half that of their usual brand; (b) "slow reduction" group which reduced to the same level in steps over several months; and (c) a control group which continued smoking cigarettes with a tar yield 10% lower than their usual brand. RESULTS: Over the course of the trial cigarette consumption declined slightly in all three groups. In both the "fast reduction" and the "slow reduction" groups, intake of COHb and cotinine was reduced, though not to the same extent as the yield reduction. Comparison of the results before randomisation with those at the end of the trial showed that a reduction in carbon monoxide yield of 45% was associated with a decrease in carbon monoxide intake of 19% (95% confidence interval 14% to 24%) and that a reduction in nicotine yield of 40% was associated with an 11% (6% to 16%) reduction in nicotine intake, reflecting relative intakes of about 1.5 for both carbon monoxide and nicotine in the "fast reduction" group. Results were similar in the "slow reduction" group with a 42% reduction in carbon monoxide yield, a 16% (11% to 22%) reduction in carbon monoxide intake, a 37% reduction in nicotine yield, and a 6% (0% to 13%) reduction in nicotine intake. Estimates of compensation derived from these results were 65% for carbon monoxide, 79% for nicotine, and 62% for tar. CONCLUSIONS: Compensation, demonstrated when switching from a high tar cigarette to a low tar one, was incomplete. Advising people who have failed to give up smoking to switch to low tar cigarettes will reduce the intake of smoke constituents to a small extent. This would be expected to decrease their risk of smoking-related diseases, although by a smaller amount than would be achieved by giving up smoking altogether.

Adaptation, Psychological↗
PubMed1995

Commercially-prepared allograft material has biological activity in vitro.

The well-established finding that implantation of demineralized bone matrix at non-skeletal sites results in formation of cartilage and bone has been attributed to bone morphogenetic proteins/factors. Commercially-available demineralized bone allograft materials are being used currently to reconstruct/regenerate bone. The studies described here focused on establishing biological activity of protein extracts prepared from commercially obtained bone graft material in vitro. Furthermore, the biological activity of these protein extracts in vitro was compared with similar extracts prepared from freshly obtained human bone. Biological activities of bone matrix proteins examined included their ability to promote proliferation, attachment, and migration of gingival fibroblasts using an in vitro system. Guanidine followed by guanidine/EDTA was used to separate bone matrix proteins into proteins associated with soft tissues of bone and proteins retained within the mineral compartment, respectively. Two preparations of each starting material were tested and the biological activity of each preparation was evaluated in triplicate at least three times. Slot blot analysis revealed that commercially-prepared material contained type I collagen; fibronectin; BSP; and BMP-2, 4, and 7. However, the freshly prepared bone extracts appeared to have higher BMP concentrations. The ability of commercial extracts to promote cell proliferation, while significant, was limited and significantly less when compared with similar extracts prepared from freshly obtained bone. All extracts promoted cell attachment significantly, while none of the extracts promoted cell migration. Thus, commercially-prepared material retained proteins having the capacity to influence cell behavior in vivo. However, some biological activity as measured in vitro was lost as a result of tissue processing.

Blotting, Western↗