Biomedical subjects

P R Stafford

Publications and source records attributed to P R Stafford.

4 recordsLinked to original sources

PubMed2001

Fractionation and characterization of phenolic resins by high-performance liquid chromatography and gel-permeation chromatography combined with ultraviolet, refractive index, mass spectrometry and light-scattering detection.

HPLC and gel permeation chromatographic (GPC) characterization of complex phenol-formaldehyde resins is described. Reversed-phase HPLC fingerprints the phenolic monomers, dimers and some oligomers. The molecular masses of these phenolic compounds were determined using an ion trap mass spectrometer. GPC analyzes tetrahydrofuran-soluble phenolic polymers beyond HPLC capability. The molecular mass distribution and structural information of the phenolics was determined by both conventional and laser light-scattering calibration methods. GPC with both UV and refractive index detection provides weight concentration of phenolic resin and the molar concentration of the phenol unit in the oligomers or polymers.

Chromatography, Gel↗

PubMed1999

Coronary interventions approaching the year 2000.

Interventional cardiology is only 22 years old, but its successes at the end of this century stand heavily on the shoulders of innovative pioneers who labored earlier in the century. Balloon angioplasty gradually developed and eventually achieved great success in treating America's greatest health risk, coronary artery disease, through the 1980s. Both mortality benefit and symptom improvement have been demonstrated for coronary angioplasty, making it one of the most frequently performed procedures in the world today. In an effort to overcome acute complications and late restenosis, atherectomy devices and stents became useful tools over the past decade. As the generation of baby boomers begins to swell the ranks of the middle aged and elderly in the early 21st century, it is with great hope that molecular biology and the continued development of the technology of interventional cardiology will allow even greater successes in decreasing death and disability from ischemic heart disease.

Angioplasty, Balloon, Coronary↗

PubMed1999

Ventricular tachycardia and sudden cardiac death.

As we approach the new millennium, treatment of survivors of cardiac arrest and prevention of sudden cardiac death (SCD) are the two most important problems confronting contemporary cardiology practice. Sudden cardiac death occurs as a result of ventricular tachycardia (VT) degenerating into ventricular fibrillation (VF). Several major arrhythmia treatment trials completed during the last decade have significantly changed the way we treat patients with ventricular arrhythmias. In patients with sustained VT and aborted SCD, only treatment with implantable cardioverter defibrillator (ICD) has been shown to significantly increase survival. Amiodarone and sotalol, though very useful in the treatment of VT and VF, do not improve survival as significantly as ICD therapy. Use of Class I antiarrhythmics may adversely affect survival. Primary prevention of SCD in patients with a recent myocardial infarction (MI) and in patients with cardiomyopathy and congestive heart failure (CHF) is limited by our inability to accurately identify patients at risk of SCD. Among the many tests available to identify patients at risk of SCD, decreased left ventricular ejection fraction (LVEF) and presence of non-sustained VT appear to be most useful. To date, only beta adrenoceptor blockers have been shown to improve survival in post-MI patients as well as in patients with cardiomyopathy and CHF. Use of amiodarone is controversial in these patients. Treatment with ICD of post-MI patients with decreased LVEF and inducible sustained VT at electrophysiology study improves survival.

Anti-Arrhythmia Agents↗

PubMed1992

Redox titrations of carbon monoxide dehydrogenase from Clostridium thermoaceticum.

Redox titrations of carbon monoxide dehydrogenase (CODH) from Clostridium thermoaceticum were performed using the reductant CO and the oxidant thionin. Titrations were followed at 420 nm, a wavelength sensitive to redox changes of the iron-sulfur clusters in the enzyme. When CODH was oxidized by just enough thionin to maximize A420, two molecules of CO per mole of CODH dimer (4 equiv/mol) reduced the enzyme fully. Likewise, 4 equiv/mol of thionin oxidized the fully-reduced enzyme to the point where A420 maximized. The four n = 1 redox sites which titrated in this region were designated group I sites. They include at least two iron-sulfur clusters, [Fe/S]A and [Fe/S]B, and two other sites, A' and B'. The [Fe4S4]2+/1+ cluster in CODH is included in this group. [Fe/S]B and B' have reduction potentials (at pH 8) below -480 mV vs NHE; [Fe/S]A and A' have reduction potentials above that value. The reduction potential of either [Fe/S]B or B' is near to the CO/CO2 couple at pH 8 (-622 mV). When CODH was oxidized by more than enough thionin to maximize A420, some of the excess thionin oxidized the so-called group II redox sites. These sites have reduction potentials more positive than group I and do not exhibit changes at 420 nm when titrated. Titration of group II sites required 1-2 equiv/mol. EPR of reduced group II sites exhibited the gav = 1.82 signal. When these sites were oxidized, the only signal present had g values at 2.075, 2.036, and 1.983.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde Oxidoreductases↗