Biomedical subjects
Publications and source records attributed to H L Price.
In the past 50 years, an increased understanding of the pathophysiologic mechanisms associated with the development of heart failure has produced a more precise treatment of this syndrome. The effects of the agents used for the treatment of patients with advanced heart failure have been summarized in this article and demonstrate the importance of vasodilatory drugs on the survival and progression of dilated cardiomyopathy.
Cardiac allograft rejection represents a major cause of morbidity and mortality in transplanted patients. Noninvasive markers of rejection have been sought, though transvenous endomyocardial biopsy remains the "gold standard" for the diagnosis of rejection. Sixty-one signal-averaged electrocardiograms (five in patients with rejection and 56 in patients without rejection) were obtained on 41 patients and prospectively analyzed in frequency domain via fast Fourier transform (FFT). Patients with acute allograft rejection demonstrate a significant increase in the high-frequency components of the QRS complex upon FFT analysis (QRS area ratio 203 +/- 57 vs. 66 +/- 10, P = 0.0007) compared with patients without rejection. Thus, frequency domain analysis may be a useful noninvasive marker of acute cardiac allograft rejection.
Your patients with heart disease may ask about transplantation. Those who are potential candidates need a physician who knows enough about the selection system to get them into it. For other patients, an explanation of why the procedure is contraindicated in their case can help them refocus on compliance with recommended therapy. The authors discuss the principles of recipient selection.
The fluorescence excitation spectrum of complexes formed from the reversible binding of the proximate carcinogen, trans-7,8-dihydroxy-7,8-dihydro-benzo[a]pyrene (BP78D) to closed-circular, single-stranded, viral M13mp19 DNA (SS M13 DNA) exhibits a red-shift of 5 nm compared to the spectrum of BP78D measured without DNA or with native, calf thymus DNA. In SS M13 DNA which is 0.10 mM in PO4-, the fluorescence intensity of BP78D is 2.3 times smaller than the intensity measured without DNA; however, the fluorescence lifetime (42.7 nsec) of BP78D with SS M13 DNA is 1.7-1.8 times larger than the lifetimes of BP78D measured without DNA or with calf thymus DNA. These results are consistent with the conclusion that, in addition to binding sites which cause fluorescence quenching, SS M13 DNA contains sites which permit formation of BP78D inclusion complexes that have weaker interactions with nucleotide bases than those occurring in intercalated complexes. The association constant (1.45 +/- 0.01 x 10(5) M-1) for the binding of BP78D to SS M13 DNA is more than 9.0 times larger than that for binding to calf thymus DNA. It is 7.1 times larger than that for the binding of the less genotoxic metabolite, trans-4,5-dihydroxy-4,5-dihydrobenzo[a]pyrene (BP45D) to SS M13 DNA. UV Photoelectron data and results from ab initio molecular orbital calculations suggest that a difference in polarizability contributes to the greater SS M13 DNA binding of BP78D compared to that of BP45D.
Dynamic and static light scattering, CD, and optical melting experiments have been conducted on M13mp19 viral circular single-strand DNA as a function of NaCl concentration. Over the 10,000-fold range in concentration from 100 microM to 1.0 M NaCl, the melting curves and CD spectra indicate an increase in base stacking and stability of stacked regions with increased salt concentration. Analysis of dynamic light scattering measurements of the single-strand DNA solutions as a function of K2 from 1.56 to 20 X 10(10) cm-2 indicates the collected autocorrelation functions are biexponential, thus revealing the presence of two decaying dynamic components. These components are taken to correspond to (1) global translational motions of the molecular center of mass and (2) motions of the internal molecular subunits. From the evaluated relaxation rates of these components, diffusion coefficients D0 and Dplat are determined. The center of mass translational diffusion coefficient D0, varies in a nonmonotonic manner, by 10%, from 3.75 X 10(-8) to 3.39 X 10(-8) cm2/s over the NaCl concentration range from 100 microM to 1.0 M. Likewise, the radius of gyration RG, obtained from static light scattering experiments, varies by 15% from 699 to 830 A over the same NaCl range Dplat, the diffusion coefficient of the internal subunits, displays a different dependence on the NaCl concentration and decreases, by nearly 22% in a titratable fashion, from 12.46 X 10(-8) to 10.26 X 10(-8) cm2/s, when the salt is increased from 100 microM to 1.0 M. A semiquantitative interpretation of these results is provided by analysis of the light scattering data in terms of the circular Rouse-Zimm chain. Rouse-Zimm model parameters are estimated from the experimental results, assuming the circular chains are composed of a fixed number of Gaussian segments, N + 1 = 15. The rms displacement of the internal segments, b, is estimated to be the smallest (442 A) in 100 mM NaCl. Increases of b to 467 A in 100 microM and 524 A in 1.0 M NaCl are observed. Meanwhile, the hypothetical friction factor of the internal subunits, f, progressively increases as the NaCl concentration is raised. It is inferred from the evaluated Rouse-Zimm model parameters that both the static flexibility of the circular chain and diffusive displacements of the internal subunits decrease with increases in NaCl concentration from 100 mM to 1.0 M.(ABSTRACT TRUNCATED AT 400 WORDS)
Percutaneous coronary angioplasty with a new passive perfusion balloon catheter was compared to a standard angioplasty balloon catheter during prolonged balloon inflations in miniature swine. Inflations with the passive perfusion balloon were alternated with a standard balloon with the initial balloon chosen randomly in 24 coronary arteries. End-points for terminating the balloon inflation were the appearance of 2 mm of ST segment deviation from baseline on the electrocardiogram, the occurrence of ventricular fibrillation, or 30 min of balloon inflation. During balloon inflation contrast injections were performed through the guiding catheter and flow distal to the balloon was graded 0-3 using the TIMI scale. The average (+/- SD) inflation time for the standard balloon was 3.1 +/- 2.2 minutes and for the perfusion balloon was 27.2 +/- 4.8 min (P less than 0.001). Electrocardiographic evidence of 2 mm of ST segment deviation from baseline was seen during 11/13 inflations with the standard balloon and in 3/11 balloon inflations with the perfusion balloon. Ventricular fibrillation occurred during 2/13 of the standard balloon inflations and in none during passive balloon inflations. Distal contrast flow during passive balloon inflations averaged 2.7 +/- 0.5 (TIMI scale 0-3) and was absent during inflations with the standard balloon. The perfusion balloon allowed prolonged inflations with excellent distal flow when compared to the standard balloon.(ABSTRACT TRUNCATED AT 250 WORDS)
The relationship of three infectious agents, Chlamydia, cytomegalovirus, and Yersinia enterocolitica, to the aetiology, clinical course, and diagnosis of Crohn's disease was studied. There was no evidence of chlamydial infection in Crohn's disease and no indication either that cytomegalovirus alters the outcome of acute attacks or that infection with Y. enterocolitica is being misdiagnosed as Crohn's disease.
Eighty-five outpatients with Crohn's disease who knew their diagnosis and that the disease was subject to relapse were interviewed. The personalities of the women as measured by the Eysenck personality questionnaire were similar to those of a control group, but the men were more neurotic and introverted. Most patients continued to live optimistic, useful lives; they felt well, continued to work, hoped that their disease would not deteriorate in the future, and often had an improved relationship with their spouse despite less frequent sexual intercourse. We found that the successful adaptation of patients to this chronic disease was more closely related to their personality than to the activity or extent of the disease.
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A 46-year-old man had advanced squamous cell carcinoma of the lung and apparent constrictive pericarditis. Echocardiographic studies twice demonstrated apparent pericardial effusions, but pericardiocenteses were unsuccessful. Tumor encasement of the heart was diagnosed clinically and at necropsy. This entity is yet another cause of a false-positive echocardiographic diagnosis of pericardial effusion.
The effects of 50 per cent nitrous oxide on isometric contractile force of electrically stimulated cat papillary muscle suspended in a Tris-buffered solution at five concentrations of Ca++ ranging from 1 to 15 mM were studied. Compared with an equal concentration of nitrogen, or with pure oxygen, nitrous oxide caused a highly significant reduction in contractile force, averaging 22 per cent at 2.5 mM Ca++. This reduction in force, like that caused by halothane, could be antagonized by increasing [Ca++] in the bathing medium. However, the reductions in force caused by equinarcotic concentrations of halothane and nitrous oxide are significantly different in magnitude, suggesting that the mechanisms of anesthetic action in the central nervous system and in the myocardium may not be the same.
Sixty-two physical therapy schools were surveyed reageding their teaching of cardiopulmonary resuscitation. Eighty-two percent of the schools responded to the questions and 27 percent indicated no such instruction. Included in this report is a copy of the questionnaire and the results of the survey. The recommendation is made that all physical therapists receive adequate training in cardiopulmonary resuscitation and that their competency be confirmed by examination.