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Biomedical subjects

B Meier

Publications and source records attributed to B Meier.

At least 181 records · Page 10Linked to original sources
PubMed1997

[Interventional treatment of heart valve diseases].

Percutaneous balloon valvuloplasty of stenoses has been introduced into medical practice in the late 70ies. Over the past decade, the method has evolved to a valid alternative to valve surgery in selected cases. Balloon valvuloplasty of isolated mitral stenosis is to date the therapy of choice and yields results comparable to those of surgery. It is even superior in only moderately diseased valves. However, the most frequent valve stenosis, that is aortic stenosis of the elderly, is not suitable for balloon dilatation. Dilatation of congenital aortic stenosis can be attempted if the valve is bicuspid or tricuspid. The recurrence rates for valvular stenoses after valvuloplasty are similar to those after surgical commissurotomy.

Aged↗
PubMed1997

[Myocardial revascularization in geriatric patients].

The results of percutaneous transluminal coronary angioplasty (PTCA) in 71 patients over 75 years of age were retrospectively analyzed and compared with those of 55 patients aged over 75 who underwent surgical revascularization (CABG) during the same time period (1992-1995). The main indication for revascularization was unstable angina. The clinical success in PTCA patients was 92%, with a lesion success rate of 93%. Major cardiac complications occurred in 5% of patients with an in-hospital mortality of 1%. The mean hospital stay was 4 days. During a follow-up period of 16 (range 1-36) months, 23% of patients treated with PTCA needed repeat revascularization (17% PTCA, 6% CABG) and 4 patients (6%) suffered nonfatal myocardial infarction. In-hospital mortality and complications were higher among the surgically treated patients (mortality 7%, major complications 45%), a fact probably related to their poorer clinical condition preoperatively. Repeat revascularization rate in the surgically treated group was 2%. The long-term mortality rate in both groups was 10%. Among long-term survivors, 92% of patients indicated that revascularization (PTCA or CABG) improved their quality of life. More than 80% led normal lives, and > 90% would undergo a second procedure if needed. In selected patients aged over 75, PTCA has a high immediate success rate with low complications and mortality. Long-term recurrence rate is high, however, and repeat revascularizations are frequent. Patient satisfaction after myocardial revascularization (PTCA or CABG) is excellent and the majority of elderly patients can lead an active and independent life.

Aged↗
PubMed1997

Therapeutic strategy with total coronary artery occlusions.

Patients with a coronary artery occlusion are more likely to be revascularized surgically or to be treated conservatively than patients without occlusion. A higher prevalence of patients with multivessel coronary artery disease (CAD), particularly with 3-vessel CAD, in the group with occlusion may account in part for this difference in management.

Angioplasty, Balloon, Coronary↗
PubMed1997

Effect of Lys175 mutation on structure function properties of Propionibacterium shermanii superoxide dismutase.

The role of electrostatic factors in the enzyme-substrate encounter process of manganese and iron containing superoxide dismutases has been studied in the enzyme from Propionibacterium shermanii by chemical neutralization of lysine residues and site-directed mutagenesis of the highly conserved residue Lys175. Lysine residues have been neutralized by carbamoylation and Lys175 has been selectively replaced by isoleucine and arginine. Catalytic measurements show a dramatic decrease of the activity in the chemically modified enzyme. Electrostatic potential calculations evidence in the modified enzyme a large contraction of the positive potential areas which surround the active sites in the native enzyme, indicating that electrostatic factors are critical in the enzyme-substrate encounter process of Mn- and Fe-superoxide dismutases. The activity drastically decreases also in Lys175-->Ile but not in the Lys175-->Arg mutant. Brownian dynamics simulations indicate that the decrease of activity in the Lys175-->Ile mutant cannot be due only to a decrease of the enzyme-substrate association rate, suggesting that Lys175 plays a relevant role also in the structural stabilization of the active site.

Binding Sites↗
PubMed1997

Intracoronary demonstration of adenosine-induced coronary collateral steal.

A steal phenomenon was detected by intravascular Doppler guidewire in a patient with a well collateralised coronary vascular area supplied by a reopened left circumflex coronary artery. This phenomenon accounted for the fall in blood flow velocity reserve during hyperaemic conditions to 50% of the baseline value. The collaterals must have been the cause of the steal phenomenon because complete revascularisation of the lesion barely reversed it.

Adenosine↗
PubMed1997

Chronic Coronary Occlusion Ñ Treatment Options and Results.

Indications for chronic coronary occlusion angioplasty are based on the projected benefit and technical difficulties. With current indications, primary success is around 60% and complications are rare. In successful cases, the main benefits are improvement of symptoms and obviation of the need for bypass surgery. Late improvement of left ventricular function can also occur. Recurrences are frequent, but reocclusions occur only in about 20% of cases. Several techniques have been advocated to improve the success rate. It is obvious that the stiffer the instrument used the higher the crossing rate, but also the risk for perforation. While the laser wire aims at high crossing success, the Magnum wire aims at high safety. In about 800 cases using the Magnum wire, the success rate was 64% before, and 66% after crossover to another technique. Complications were comparable to those of routine coronary angioplasty. Chronic total occlusions are a major reason for selecting bypass surgery over angioplasty. The technical success with angioplasty leaves room for improvement. However, safety should not be compromised and there are limits to the investment in terms of time and material because the clinical yield is relatively small, albeit uncontested.

Journal Article↗
PubMed1997

[Early percutaneous coronary angioplasty in unstable angina].

The risks of complications of percutaneous transluminal coronary angioplasty (PTCA) are increased in unstable angina. Medical treatment for a few days before PTCA is widely adopted to reduce the risk of thrombosis or occlusive dissection during and after the procedure. Over the last few years, the authors have adopted a strategy of early coronary angiography completed by immediate angioplasty when possible, without waiting for the eventual benefit of aspirin or heparin therapy. Their experience from 1988 to 1995 of 853 patients treated by PTCA (151/853 or 17.7%, with implantation of a stent) for unstable angina, was reviewed. Group I comprised 402 patients treated on the day of or the day after admission. Group II comprised 451 patients treated 2 days or more after admission. Patients in Group I were younger (62 +/- 11 vs 64 +/- 12, p < 0.001), and had single vessel disease more often (61 vs 52%, p < 0.005). The success rate of PTCA was similar in the 2 groups (85.3 vs 88.2%, NS), as was the rate of complications (death, infarction or coronary bypass surgery, 9.9 vs 7.3%, NS). The length of hospital stay was significantly shorter in Group I (6.1 +/- 5.6 vs 8.7 +/- 6.9 days, p < 0.0001). With the limitations inherent to all retrospective studies, these data suggest that an early interventional approach in unstable angina has a similar success rate with no more complications than angioplasty. This approach is associated with a deferred significant decrease in the duration of hospital stay.

Aged↗
PubMed1996

HDF2, the second subunit of the Ku homologue from Saccharomyces cerevisiae.

The high affinity DNA binding factor (HDF) protein of Saccharomyces cerevisiae is composed of two subunits and specifically binds ends of double-stranded DNA. The 70-kDa subunit, HDF1, shows significant homology with the 70-kDa subunit of the human Ku protein. Like the Ku protein, HDF1 has been shown to be involved in recombination and double stranded DNA break repair. We have purified and cloned HDF2, the second subunit of the HDF protein. The amino acid sequence of HDF2 shows a 45.6% homology with the 80-kDa subunit of the Ku protein. HDF1 by itself does not bind DNA, while HDF2 protein on its own seems to displays DNA binding activity. Targeted disruption of the HDF2 gene causes a temperature-sensitive phenotype for growth comparable to the phenotype of hdf1(-) strains. The human Ku protein cannot complement this temperature-sensitive phenotype. hdf2(-) strains are sensitive to bleomycin and methyl methanesulfonate, but this sensitivity is reduced in comparison with hdf1(-) strains.

Antigens, Nuclear↗