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Biomedical subjects

C Deck

Publications and source records attributed to C Deck.

18 recordsLinked to original sources
PubMed2004

Human Neck Finite Element Model Development and Validation against Original Experimental Data.

This study proposes a detailed FEM of a human volunteer's neck and proceeds to an original model validation against experimental data recorded with this human volunteer. In order to evaluate the new model against existing data a successful temporal validation of the model was obtained under frontal, lateral, oblique and rear impact. New validation parameters are based on an experimental test proceeded in the frequency domain in order to extract the volunteer's Head-Neck system's modal characteristics. In depth validation of the head neck FEM is then performed by superposing the numerical and experimental frequency response function. Model optimisation in the frequency domain permitted after significant properties modification to reproduced accurately both, the neck extension mode at 1.4 Hz and the head retraction mode at 8.8 Hz. Finally the "frequency domain optimised" FEM response was superimposed with the temporal corridors provided in the literature. It must be mentioned that the model's response in the temporal domain remains inside existing corridors after this model optimisation in the frequency domain illustrating that the temporal validation is not accurate enough. This study proposes a neck model with improved geometry description and biofidelity with special attention paid to the retraction mode, a phenomenon which is often masked in the temporal domain.

Journal Article↗
PubMed2001

Predictors of radial artery patency for coronary bypass operations.

BACKGROUND: Few data exist regarding angiographic predictors of radial artery patency for coronary bypass grafting, and the benefit of calcium antagonists is not clear. METHODS: One hundred fifteen patients were studied who had myocardial revascularization with the radial artery plus internal mammary and vein grafts with 3.5 +/- 1.1 grafts per patient. Sixty-three patients received diltiazem and 52 patients did not. Base line and follow-up angiographies were analyzed 1 year postoperatively in 50 of these patients with a quantitative computerized method. RESULTS: One hundred fourteen patients survived and were followed for 30.1 +/- 12.6 months. Patency for mammary grafts was 100%, for radial grafts it was 80%, and for saphenous vein grafts it was 68%. Patent radial artery grafts had significantly greater degree of stenosis in the native vessels than occluded grafts (73% +/- 14% vs 40% +/- 24%), (p = 0.0007; confidence interval = 95%). Radial artery patency increased to 92% when arteries with 70% or more stenosis were considered. No differences were observed for clinical and angiographic end points in the patients that received diltiazem compared with the rest who had not. CONCLUSIONS: The degree of stenosis in the native coronary artery significantly influences the patency rate of radial artery grafts, independent of diltiazem.

Adult↗
PubMed1997

Interferon-beta induces S phase accumulation selectively in human transformed cells.

Interferons (IFNs) generally have been characterized as antiproliferative cytokines. The cell cycle arrest in G1/G0 phase induced by type I IFNs, especially IFN-alpha, was recognized as a manifestation of their antiproliferative effects. In this article, we report that the cell cycle block in G1/G0 is observed mainly in certain cell types, such as Daudi Burkitt's lymphoma cells. In a variety of human transformed cells, but not nontransformed primary cells, IFN-beta and IFN-alpha induced a significant increase in the S phase population. The increase appeared to be due to a continued S phase entry and subsequently a failure of S phase cells to transit efficiently into G2 and M phases. The ability of tumor cells to exhibit the S phase effect correlated with proper IFN signaling and loss or inactivation of the normal G1 checkpoint conferred by the retinoblastoma protein (pRB). Overriding the G1 checkpoint switched human nontransformed primary cells from nonresponsive to sensitive to the IFN-induced effect. Therefore, the cell cycle regulatory machinery could function, at least in part, as a determining factor that affects the IFN-induced cell cycle effect. The IFN effect in transformed cells may suggest intriguing prospects for combinatorial therapies for cancer.

Cell Cycle↗
PubMed1991

Beta-adrenergic blocker therapy does not worsen intermittent claudication in subjects with peripheral arterial disease. A meta-analysis of randomized controlled trials.

Beta-Adrenergic blockers have been considered relatively contraindicated in peripheral arterial disease because of the perceived risk that these drugs could worsen intermittent claudication. Therefore, we conducted a meta-analysis of available randomized controlled trials from the English-language literature to determine whether or not beta-blockers exacerbate intermittent claudication. The primary focus of this analysis was the effect of beta-blockers on exercise duration, measured as walking capacity or endurance time. Outcomes were pooled where appropriate. Of 11 eligible reports, six included 11 individual controlled treatment comparisons that provided data for an analysis of pain-free exercise capacity; no effect size was statistically significant. The pooled effect size for pain-free walking distance was -0.24 (95% confidence interval, -0.62 to 0.14), indicating no significant impairment of walking capacity compared with placebo. Only one study reported that certain beta-blockers were associated with worsening of intermittent claudication. These results strongly suggest that beta-blockers do not adversely affect walking capacity or symptoms of intermittent claudication in patients with mild to moderate peripheral arterial disease. In the absence of other contraindications, beta-blockers can probably be used safely in such patients.

Adrenergic beta-Antagonists↗
PubMed1991

The effects of low doses of n-3 fatty acid supplementation on blood pressure in hypertensive subjects. A randomized controlled trial.

The potential antihypertensive effects after prolonged use of small doses of fish oils remain undefined. Therefore, we conducted a randomized, double-blind, controlled crossover study comparing low doses of n-3 fatty acid supplementation with n-6 fatty acids on blood pressure in 33 subjects with mild hypertension. After a 6-week stabilization period, subjects ingested either 2.04 g/d of n-3 fatty acids or safflower oil (4.8 g/d of linoleic acid) for 12 weeks, then crossed over to the alternative encapsulated oil for another 12 weeks, after a 4-week washout period. All antihypertensive drug therapy had been discontinued. For the combined data, there were significant reductions from pretreatment values for supine diastolic (-2.4 mm Hg) and sitting systolic (-4.1 mm Hg) blood pressure after fish oil; no significant changes occurred after safflower oil control. Compared with safflower oil, fish oil supplementation was associated with a statistically significant reduction in mean supine diastolic blood pressure of 3.7 mm Hg (95% confidence interval, -7.3 and 0.1). Sitting diastolic and mean arterial pressures showed a sequence effect; therefore, only the initial period was used in an analysis of their responses. There were significant decreases from pretreatment values for sitting diastolic (-4.4 mm Hg), mean arterial (-5.1 mm Hg), and systolic (-6.5 mm Hg) blood pressure after fish oil. The differences between groups after the 12-week period remained statistically significant for sitting diastolic and sitting mean arterial blood pressures. No adverse changes were noted in plasma levels of lipid-related measures.

Adult↗
PubMed1990

The comparative effects of n-3 and n-6 polyunsaturated fatty acids on plasma fibrinogen levels: a controlled clinical trial in hypertriglyceridemic subjects.

It has previously been shown that fish oil supplementation, compared to olive oil, reduces plasma fibrinogen. Presented here are the results of a randomized, double-blind, crossover controlled trail that compared the effects of dietary n-3 and n-6 fatty acid supplementation on plasma fibrinogen levels in 10 patients with hyperlipoproteinemia types IIb or IV. Plasma fibrinogen levels showed statistically significant reductions during both the fish oil and corn oil treatment periods. Other variables related to hemostasis which showed no significant changes from baseline included tissue plasminogen activator activity and inhibitor, protein C antigen, antithrombin III activity, bleeding time, and platelet counts. These data confirm the two previous reports that fish oil supplementation is associated with reductions in plasma fibrinogen levels, thereby modifying a potential nonlipid risk factor for cardiovascular disease. Unlike previous reports, however, n-6 polyunsaturated fatty acids were also associated with significant reductions in fibrinogen levels. Therefore, it is premature to conclude that the fibrinogen-lowering effects of dietary fish oil are unique to n-3 polyunsaturated fatty acids.

Corn Oil↗
PubMed1990

[Wegener's granulomatosis: clinical and pathological report of 22 cases].

We report clinical and pathologic findings in 22 patients with Wegener's granulomatosis collected from 1966 to 1989. Ten cases were analyzed retrospectively. Organs affected included the lungs (n = 18), upper airways (16), kidneys (15), musculo-skeletal system (10), eyes (8), skin (7) and ear (5). Clinical manifestations of airway involvement included nasal obstruction, dysphonia and epistaxis. Lung involvement was evident in chest X-rays in 18 patients, 14 with a nodular aspects. Histologic study in 14 of these patients showed necrotizing and granulomatous vasculitis. Clinical evidence of nephropathy was evident in 15 patients and led to rapidly progressive renal failure in 8. Biopsy in this group (n = 14) revealed focal glomerulonephritis in 6 and diffuse disease in 8. Overall, 13 patients died: 5 without diagnosis, 4 from renal failure, 2 from sepsis, 1 from a lymphoma developing 3 years after immune suppressive therapy and 1 from unknown causes. Among survivors, one received a renal transplant and one remains in chronic dialysis. The diagnosis of Wegener's granulomatosis is therefore based on clinical findings including rhino pharyngeal, pulmonary and renal manifestations.

Adult↗
PubMed1989

The effects of omega-3 polyunsaturated fatty acids on blood pressure: a methodologic analysis of the evidence.

The potentially beneficial blood pressure (BP)-lowering effects of marine omega-3 polyunsaturated fatty acids (omega-3-PUFAs) remain controversial. The objective of this qualitative and quantitative (meta-analysis) analysis was to evaluate the results of all available randomized controlled trials that studied the effect of omega-3-PUFAs on BP response. A comprehensive search of the English literature from 1970 to 1988 disclosed only six randomized controlled investigations out of 22 published reports. Four of these were evaluable and therefore eligible for this analysis. Of these, only one evaluated hypertensive subjects. In two trials, there were statistically significant reductions in BP; the one reporting an investigation of hypertensive subjects showed the greatest reduction. Using established methodologic criteria, the quality of each report was evaluated by independent observers. Following this appraisal, the outcomes of each investigation were reanalyzed and pooled using a meta-analysis. There was no statistically significant difference between the omega-3-PUFA groups and the control groups, possibly because of failure to include hypertensive subjects in all but one trial. Despite the positive effects in two studies, little scientifically valid evidence is available to demonstrate a significant BP-lowering effect of omega-3-PUFAs. Areas needing more attention in future research are identified and methods to improve study designs are suggested.

Blood Pressure↗
PubMed1989

Effects of modest doses of omega-3 fatty acids on lipids and lipoproteins in hypertriglyceridemic subjects. A randomized controlled trial.

Unlike the well-established hypotriglyceridemic effect of omega-3 fatty acid supplementation, the influence of more clinically tolerable doses on lipoproteins and apolipoproteins is less well characterized. Therefore, we compared the relative effects of modest doses of omega-3 fatty acid supplementation with a corn oil control on lipids, lipoproteins, and apolipoproteins in a randomized, double-blind controlled crossover study. Eight hypertriglyceridemic subjects ingested 4.6 g/d of omega-3 fatty acids or 5.4 g/d of linoleic acid (supplied as corn oil) for 8 weeks, then crossed over to the alternative encapsulated oil for another 8 weeks, following an interposed 4-week wash-out period. Compared with the corn oil control, fish oil supplementation caused a significant reduction in triglyceride levels by a mean of 2.21 mmol/L and increased the high-density lipoprotein cholesterol by a mean of 0.13 mmol/L, associated with a significant rise in the high-density lipoprotein 3 subfraction. Furthermore, there was a significant increase in low-density lipoprotein (LDL) apolipoprotein B levels by a mean of 0.246 g/L. Compared with corn oil, no statistically significant change for LDL cholesterol or other apolipoprotein levels occurred, although LDL cholesterol showed a mild elevation. These data suggest that unlike large doses of omega-3 fatty acids, the hypotriglyceridemic effect of modest amounts of encapsulated fish oil supplementation is unaccompanied by favorable changes in LDL cholesterol or LDL apolipoprotein B levels; the potential therapeutic usefulness of modest doses of dietary fish oil for the treatment of hypertriglyceridemia, therefore, may be limited.

Adult↗
PubMedDate not supplied

Do nonsteroidal anti-inflammatory drugs interfere with blood pressure control in hypertensive patients?

Exacerbation of hypertension by nonsteroidal anti-inflammatory drugs in hypertensive patients remains controversial among physicians and investigators. Because of the many differences among studies of oral nonsteroidal anti-inflammatory drugs and blood pressure control in patients with hypertension, the authors critically evaluated the published clinical evidence on this subject using standardized methodologic criteria. A search of the literature from 1965 to 1986 identified 31 relevant studies, of which only eight were double-blind randomized controlled trials that provided the most clinically useful information. Of these eight best-designed studies, five of the six that studied indomethacin concluded that it may interfere with antihypertensive effectiveness in selected patients with treated, stable hypertension. The remaining double-blind randomized studies included comparisons of other nonsteroidal anti-inflammatory drugs. Their limited results suggest that sulindac is less likely than piroxicam, naproxen or indomethacin to cause an attenuation of antihypertensive therapy. More research on this subject is needed, with greater attention to methodologic details and identification of predisposing risk factors for impairment of blood pressure control by nonsteroidal anti-inflammatory drugs.

Anti-Inflammatory Agents, Non-Steroidal↗