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Biomedical subjects

P Goy

Publications and source records attributed to P Goy.

11 recordsLinked to original sources
PubMed2000

Ultrawide band multifrequency high-field EMR technique: A methodology for increasing spectroscopic information.

We report methodology that combines an ultrawide band multifrequency microwave system with technology of high magnetic fields for solving challenging problems in electron magnetic resonance (EMR) spectroscopy. This strategy has been made possible due to a novel EMR facility operating in an exceptionally wide range of microwave frequencies of 24 GHz to 3 THz, at magnetic fields up to 17 T, and in the temperature range of 1.6 to 330 K. The basic configuration of the multifrequency system works in a transmission mode and employs oversized cylindrical waveguides for routing the microwave power. A wide-band, low-noise, liquid helium cooled (4.2 K) InSb bolometer is used for signal detection. This approach results in an extremely wide-band performance, thus making it possible to employ a variety of solid-state millimeter and submillimeter microwave sources in combination with a far infrared laser microwave source for performing multifrequency EMR experiments. A complexity of resonant structures and related technical problems such as microphonics at high magnetic fields is virtually eliminated. The system is simple, yet sensitive, and has been revealed to be extremely advantageous while solving such problems as observation of AFMR transitions in spin-ordered systems, g-factor resolution enhancement in complex organic radicals, and resonance signal detection in EMR-silent spin systems having integer spin and large zero field splitting. A technical description of the multifrequency high-field EMR facility is presented and results of its performance tests are given. The potential utility of using the multifrequency high-field methodology in EMR studies is illustrated with selected examples of its recent applications.

Electron Spin Resonance Spectroscopy↗
PubMed1998

[Coronary angiography by a radial artery approach: feasibility, learning curve. One operator's experience].

The aim of this study was to assess the feasibility of the radial artery approach for coronary angiography in a standard population of presumed coronary patients and to continue the assessment for a sufficiently long period of time to perfect the technique, evaluate the learning curve and prepare a randomised comparison with the femoral approach. The radial artery was used for coronary angiography in 800 patients after exclusion of about 25% of patients, mainly because of a negative Allen's maneuver. With the exception of acute myocardial infarction, there was no selection based on symptoms and transradial catheterisation was attempted irrespective of age, sex, weight or height. The representative nature of the study population was confirmed by the results of the procedure (normal: 20%, single vessel disease: 30%, double vessel disease: 26%, triple vessel disease: 18% and left main disease: 5.4%). The right radial artery was used in 94% of cases. Successful radial puncture/catheterisation was obtained in 97% of cases: 100% of left coronary arteries and 99% of right coronary arteries were catheterised, the left ventricle in 98% of cases, the internal mammary arteries in 100%, and venous bypass grafts in 95%. The average duration of the whole procedure was 19 +/- 9 minutes. This decreased regularly with operator experience and judicious choice of catheters. The best choice seemed to be a single catheter for both coronary arteries, either an Amplatz or a Champ catheter. There were two probably avoidable coronary complications and two transient neurological events but no clinically significant vascular complication. The radial artery seemed to be a good approach for routine coronary angiography and may now be compared with the femoral approach. It should help expand the practice of ambulatory coronary angiography.

Aged↗
PubMed1997

A randomized trial of a fixed high dose vs a weight-adjusted low dose of intravenous heparin during coronary angioplasty.

AIMS: Prospectively to compare success rate and complications in percutaneous transluminal coronary angioplasty using two doses of heparin. METHODS AND RESULTS: Four hundred patients undergoing coronary angioplasty were randomly assigned to receive 15,000 IU (group A) or 100 IU.kg-1 (group B) of heparin. The angioplasty success rate was 95% of both groups. Stents were placed in 28.5% and 26.5% of patients in groups A and B, respectively (P = 0.73). The primary endopoint (freedom from death, myocardial infarction, unplanned revascularization or bailout stenting) occurred in 91% vs 95% of patients in groups A and B, respectively (odds ratio: 1.88, 95% CI: 0.80-4.50, P = 0.12). Haemoglobin loss was 0.36 +/- 1 and 0.27 +/- 0.9 g.dl-1 in groups A and B, respectively (P = 0.37). The time to sheath removal (735 +/- 265 vs 558 +/- 246 min) and the time to transfer to a stepdown unit (12.7 +/- 4.5 vs 9.8 +/- 4.2 h) were longer in groups A (P = 0.0001 for both comparisons). CONCLUSION: A weight-adjusted low dose of intravenous heparin is at least as safe as a fixed high dose for coronary angioplasty. It allows earlier sheath removal and discharge to a stepdown unit.

Adult↗
PubMed1980

Tolerance of autosomal imbalance by the Syrian hamster (Mesocricetus auratus).

Cytogenetic and transmission data are given for a number of radiation-induced and spontaneous chromosomal changes which show that the Syrian hamster (Mesocricetus auratus) can tolerate a considerable amount of autosomal imbalance without phenotypic effect. It is suggested that the reason for this may lie in the very large amount of late-replicating chromatin present in this species.

Animals↗
PubMed1979

Routine chromosome screening in Syrian hamsters (Mesocricetus auratus) using orbital sinus blood.

Blood from the posterior orbital sinus of Syrian hamsters, obtained under halothane anaesthesia, can be cultured to give large numbers of metaphase chromosome spreads for analysis. The procedure has been used for rapid routine screening of the karyotypes of all offspring in a breeding colony where translocations are present. Results can be obtained within 3 days of collecting the blood sample.

Anesthesia, Inhalation↗