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Biomedical subjects

J D Barth

Publications and source records attributed to J D Barth.

At least 19 recordsLinked to original sources
PubMed2003

Sonographic reproducibility of a novel approach in the assessment of centralised access in end-stage renal disease.

A reliable and accurate non-invasive test is needed to help determine grafts and/or fistulae in end-stage renal disease (ESRD) patients. Sonographic scanning to assess the state of the fistula and AV shunt seems underused. To find out what role B-mode and Doppler play in the assessment of fistula and shunt, we scanned nine patients with a fistula as central access and nine patients with a graft several times over a period of a month. Diameters were measured before and after the AV shunt and Doppler measurements were made pre, inter and post shunt. We established that B-mode measurements are reliable in predicting the future and integrity of both fistulae and grafts. Doppler measurements were less consistent and therefore less reliable. The average initial measurement showed a screen of 5.766 mm and a second measurement of 5.890 mm; The coefficient of variation (CV)/reproducibility was 1.58% for first measurement. The average first and second measurements post graft were 6.317 mm and 6.365 mm, respectively. The CV/reproducibility was 0.48%. First and second peak flow measurements averaged 149 m/s and 112 m/s, respectively, resulting in a CV of 14.0%. We conclude that morphological changes may be more reliable than Doppler values, indicating a potentially greater use for B-mode ultrasound in predicting an open shunt and/or fistula.

Adolescent↗
PubMed2001

Which tools are in your cardiac workshop? Carotid ultrasound, endothelial function, and magnetic resonance imaging.

There are several techniques for assessing arterial health, including carotid ultrasound, endothelial function, and magnetic resonance imaging. Each has pros and cons, but which technique is best? Quantitative intima medial thickness (QIMT) is safe, validated, portable, has a reference database, is inexpensive, and can be used in multicenter studies. Magnetic resonance imaging may be useful clinically, but it is still considered experimental and remains a costly procedure. Flow-mediated dilation (FMD) is a good surrogate measure, reflecting initial risk, indicating very early disease, and demonstrating rapid response to change. All the imaging methods require standardization of tools, operator training, specification of populations studied, and other considerations to be of use in the clinical setting.

Arteriosclerosis↗
PubMed1995

Effects of vitamin E on endothelial function in men after myocardial infarction.

This study showed that endothelial dysfunction is present in men 3 to 6 months after myocardial infarction, but was unable to show any improvement in endothelial function after 3 months of therapy with vitamin E 800 IU/day. Further studies are necessary to determine whether higher doses or a longer course of vitamin E, or whether other antioxidant agents with or without lipid-modifying activity, would improve endothelial function.

Acetylcholine↗
PubMed1995

Lipoproteins and the progression/regression of atherosclerosis.

Lipoproteins and the impact of lipid lowering on progression and regression of coronary artery disease are discussed. Angiographically assessed regression studies are reviewed (NHLBI, LIT, LHT, CLAS I and II, FATS, POSCH, Heidelberg, STARS, SCRIP, MAAS, PLAC I, HARP, UC-SF), as are B-mode ultrasound studies (ACAPS, PLAC II) and survival studies (Oslo diet-smoking study, SSSS, Pravastatin, Oxford). Although study populations and the interventions are different in the studies, I have come to the following conclusions. Regression of atherosclerosis correlates well with reduction in LDL cholesterol and an increase in HDL cholesterol. Although overall improvement in the severity and extent of the disease was modest, reduction of clinical events was impressive. Lipid modulation may stabilize existing lesions by improving the stability of the lesion cap and/or promoting loss of cholesterol content from within the plaque. Survival studies indicate that lipid lowering lowers morbidity and increases longevity in patients with established coronary heart disease. The B-mode ultrasound studies using the carotid artery as surrogate for the change in atherosclerosis in the coronary seems extremely promising. The atherosclerotic process as well as complications may be studied at an early stage using noninvasive methods.

Arteriosclerosis↗
PubMed1995

An update on lipid-lowering therapy.

New information on the effects of lipid-lowering drugs is reviewed with an emphasis on special groups that benefit from specific drug therapy. Although it has been shown that the diet may further enhance the effectiveness of lipid-lowering drugs, compliance to diet and drugs remains an important issue and the large individual variations in dietary responses should be studied more extensively. The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors are safe and effective in different populations such as in women, elderly people and in special cases of secondary hyperlipidaemia. More widespread implementation of screening programmes to identify suitable patients for lipid-lowering therapy may help prevent the excess utilization of health care resources.

Aged↗
PubMed1995

Pixel or death: experience from clinical trials assessing lipid lowering therapy.

Repeated coronary angiography has become a surrogate for clinical events in studies involving lipid lowering treatment. Different lipid lowering interventions have resulted regression in approximately 20% of subjects. Clinical events decreased more rapidly and more profoundly than can be explained by morphological remodeling. Regression of atherosclerosis correlates well with reductions in serum low density lipoprotein (LDL) cholesterol and with increases in high density lipoprotein (HDL) cholesterol. Although overall improvement in severity and extent of the disease was modest, reduction of clinical events was impressive. Lipid modulation may stabilize existing lesions by improving the stability of the lesion cap and/or promoting loss of cholesterol content from within the plaque. Survival studies indicate that lipid lowering decreases morbidity and increases longevity in patients with established coronary artery disease. The B-mode ultrasound studies using the carotid artery as surrogate for the assessment of atherosclerosis in coronary arteries seems extremely promising. The atherosclerotic process as well as complications may be studied in an early stage using noninvasive methods.

Cholesterol, HDL↗
PubMed1993

Beneficial effects of colestipol-niacin therapy on the common carotid artery. Two- and four-year reduction of intima-media thickness measured by ultrasound.

BACKGROUND: Controlled clinical trials have reported treatment effects evaluated with serial imaging in coronary and femoral but not cervical arteries. The Cholesterol Lowering Atherosclerosis Study, a coronary, cervical, and femoral angiographic trial of colestipol plus niacin, included a pilot study of standardized carotid ultrasound imaging. METHODS AND RESULTS: Seventy-eight subjects had ultrasound studies at baseline, 2, and 4 years. Twenty-four drug and 22 placebo subjects had carotid ultrasound images at baseline, 2, and 4 years with matching cervical angiograms. Computer image processing was applied to ultrasound images of common carotid (far wall) and cervical angiograms. Computer operators were blind to treatment group. Carotid ultrasound measurements were tested for treatment effects and compared with measurements of atherosclerosis in coronary and cervical angiograms. Drug subjects showed significant progressive reduction in carotid thickness at 2 (P = .0001) and 4 years (P = .0001); placebo subjects significantly increased wall thickness at 2 and 4 years. Reduced levels of apolipoprotein B and increased levels of high density lipoprotein cholesterol and apolipoprotein C-III were significant predictors of carotid wall thinning. Ultrasound-measured carotid intima-media thickness was correlated at baseline with visually read coronary angiographic stenosis and at 2 years with a robust computer measurement of mild carotid atherosclerosis. CONCLUSIONS: Common carotid intima-media thickening can be reduced by colestipol-niacin treatment. Two-year image-processed carotid ultrasound trials can provide adequate power with 50 subjects per group to test for this treatment effect.

Adult↗
PubMed1993

Acute right ventricular heart failure in a patient with renal cell carcinoma after interferon therapy.

In a patient with diffuse pulmonary metastases of a renal cell carcinoma the development of severe pulmonary hypertension is described after reaching a complete remission during treatment with r-IFN-alpha 2c and rIFN-gamma. Rechallenge with interferon after the discovery of recurrent disease did not lead to deterioration of the cardiopulmonary condition. Possible causative mechanisms are discussed.

Acute Disease↗
PubMed1992

Regression growth evaluation statin study (REGRESS): study design and baseline characteristics in 600 patients. The REGRESS Research Group.

OBJECTIVE: To assess the effects of lipid lowering, using a hydroxymethyl glutaryl coenzyme A reductase inhibitor (pravastatin) in symptomatic men with coronary artery disease. To assess follow-up intervention modes and baseline cardiovascular risk factors in men after routine diagnostic coronary arteriography which showed a significant stenosis (at least 50%) in a major segment. DESIGN: Baseline characteristics are stated in a multicentre, prospective, double-blind, randomized, placebo-controlled trial entitled 'regression growth evaluation statin study' (REGRESS). SETTING: Seven university hospitals and four referral hospitals in The Netherlands. PATIENTS: The baseline characteristics are given for the initial 600 patients who entered the REGRESS trial. All patients were 'normocholesterolemic' and suffered from symptomatic coronary artery disease. INTERVENTION: Initial follow-up treatment was analyzed after coronary arteriography, in accordance with standardized clinical practice (angioplasty, bypass grafting or medical management only). MAIN RESULTS: In contrast to routine procedures, 44% of the patient population was found in the medical management only stratum, whereas 32% was found in the coronary bypass graft and 24% in the percutaneous transluminal coronary angioplasty stratum. No major coronary cardiovascular risk factor could explain the decision to perform a certain follow-up intervention. Overall patients showed a low serum high density lipoprotein (HDL) cholesterol level. A higher New York Heart Association classification for anginal complaints tended to favour a more aggressive follow-up approach. CONCLUSIONS: The total REGRESS population showed relatively low HDL cholesterol blood levels compared with the general Dutch population. The rationale to perform a specific follow-up intervention by the treating cardiologist is unclear. Severity of anginal complaints may lead to a more active intervention procedure.

Aged↗
PubMed1991

Progression and regression of atherosclerosis, what roles for LDL-cholesterol and HDL-cholesterol: a perspective.

Numerous observational and intervention studies have shown that total (and LDL) cholesterol levels correlate positively with progression of atherosclerosis. It has also been shown that a mean low HDL cholesterol level is a potent predictor of CHD (coronary heart disease) in populations in which atherosclerotic diseases are prevalent. Recently, studies based on repeat angiographic examination, which are reviewed here, have shed new insight on the different roles that total cholesterol (or LDL) and HDL-cholesterol play on progression and regression of coronary atherosclerosis, respectively. From an epidemiological viewpoint, based on observational as well as intervention studies, the theory emerges that progression correlates best with total (and LDL-) cholesterol and that regression correlates best with HDL-cholesterol. The working hypothesis, if confirmed, will have practical implications for primary and secondary preventive measures.

Animals↗