What is the evidence that osteoarthritis is genetically determined?

Although for many years it was speculated that osteoarthritis was genetically determined, little data were available to support this contention. A major problem with early work was a lack of consistency in the definition of osteoarthritis. Based on a radiographical definition of osteoarthritis, which is currently the optimal method for epidemiological and genetic studies, data from a recent twin study have provided an estimate of the hereditable component of osteoarthritis to be in the order of 50 to 65%. In addition, sophisticated molecular biology techniques are being increasingly used to explore potential genetic abnormalities in cartilage and matrix components in osteoarthritis. These exciting new data are examined as we address the role of genetic factors in osteoarthritis.     

Substrate selectivity and biochemical properties of 4-hydroxy-2-keto-pentanoic acid aldolase from Escherichia coli

4-Hydroxy-2-keto-pentanoic acid aldolase from Escherichia coli was identified as a class I aldolase. The enzyme was found to be highly selective for the acetaldehyde acceptor but would accept alpha-ketobutyric acid or phenylpyruvic acid in place of the pyruvic acid carbonyl donor.     

A cell-kinetics model for radiation-induced myelopoiesis

A mathematical model of time-dependent cellular damage, repair, killing and repopulation of bone marrow following treatments with ionizing radiations is described. Effects from variable dose rates, multiple exposures, different radiation sources and arbitrary intervals between treatments can be modeled by ordinary differential equations. Of several unique features, the most unusual is that rate constants for injury, repair, killing and proliferation of cells are evaluated by likelihood analysis of animal mortality data. Results indicate that a relatively radioresistant pool of bone marrow cells mediates the proliferation of the hematopoietic stem cells. Applications include modeling of 1) myelopoietic integrity as a function of time and dose rate, 2) the whole-body survival curve (at any point in the treatment protocol) for cells critical to myelopoiesis, 3) a prompt dose equivalence from any completed portion of a therapeutic schedule and 4) potential gain from schedule changes during the course of the treatment.     

Formal education and back-related disability. In search of an explanation

STUDY DESIGN: The present study is a 2-year prospective study with repeated measurements. OBJECTIVES: To examine the association of education with back-related disability along with four sets of variables that might explain this relationship: clinical, behavioral, and environmental factors; occupational variables; health care use; and interactions between stressful events and coping strategies. SUMMARY OF BACKGROUND DATA: Although education has been found to be associated with back-related disability in previous reports, this relationship remains to be explained. Examination of this association may yield a better understanding of the causes and natural history of disability resulting from back pain. METHODS: Subjects were 1213 enrollees of a Health Maintenance Organization (HMO) who consulted a primary care physician for back pain in 1989-1990, completed a baseline telephone interview, and had a follow-up evaluation after 1 and 2 years, using a modified version of the Roland-Morris Scale to measure disability. RESULTS: Subjects who completed 13 years or more of schooling had less disability and a greater decline in their disability over time than those who completed less schooling. Occupational characteristics and somatization were among the strongest explanatory factors. Cigarette smoking contributed to the explanation of the cross-sectional association. CONCLUSIONS: Education is associated cross-sectionally and longitudinally with disability resulting from back pain. A wide range of variables may mediate the education-back-related disability association, including a propensity to report diffuse physical symptoms (somatization), lifestyle (e.g., cigarette smoking), and occupational factors.     

Effect of rapid digitalization on the left-ventricular myocardial function according to the echocardiographic data

The article deals with the data of echocardiographic examination of 61 patients (37 with rheumatic heart disease and 17 with atherosclerotic cardiosclerosis) subjected to rapid stage-by-stage digitalization by intravenous administration of various rapidly acting glycosides. In 10 patients with ischemic heart disease echocardiography was performed following a single strophanthin injection. Decrease in the volumes of the left ventricle and increase in the indices of central hemodynamics were noted as a result of rapid stage-by-stage saturation with strophanthin. The maximum inotropic effect of strophanthin does not coincide in time with the maximum chronotropic effect. The increase in the stroke volume noted in maximum deceleration of cardiac contractions is probably realized due to the Frank-Starling mechanism. Strophanthin increases the rate of myocardial contractions without changing the duration of the systole. The rate of diastolic relaxation grows, the phase of rapid filling becomes shorter and the phase of slow filling longer, which creates favourable conditions for the next contraction.     

Cardiovascular effects of a new inotropic agent, U. K. 14275, in patients with coronary heart disease

1 The chronotropic and inotropic properties of U.K. 14275, a phosphodiesterase inhibitor were assessed in patients with coronary heart disease. 2 Left ventricular function was assessed in eight patients with acute myocardial infarction using the non-invasive measurement of systolic time intervals. 3 Twelve patients with angina pectoris were studied during diagnostic coronary arteriography. Left ventricular function was assessed using a high fidelity catheter tipped transducer in the left ventricle. 4 In both groups of patients U.K. 14275 infused intravenously in doses of 32, 64, 128 and 256 microgram kg-1 bodyweight min-1 enhanced the contractile state of the left ventricle without altering the heart rate.