Hydrogen peroxide-mediated corneal endothelial damage. Induction by oxygen free radical

Polymorphonuclear leukocytes and other inflammatory cells release superoxide anion and additional oxidant species following stimulation. Corneal endothelial cells were exposed to a flux of chemically generated superoxide anion (oxygen-free radical) produced by the combination of 1 mM hypoxanthine and 0.06 U/ml xanthine oxidase. Exposure of endothelial cells to the combination of hypoxanthine and xanthine oxidase resulted in anatomic disruption of the cells with interference in the function of endothelial water movement and resultant swelling of the corneal stroma. Catalase reduced the corneal swelling caused by exposure of endothelium to the oxygen-free radical generating system, whereas superoxide dismutase, ascorbic acid, D-mannitol, and ethanol did not prevent damage. The data suggest that hydrogen peroxide produced during the dismutation reaction of the superoxide anion is one of the toxic species, whereas the superoxide anion itself and the hydroxyl-free radical probably do not participate. The data suggest that corneal endothelial cells are susceptible to physiologic and anatomic damage induced by the products of reactive oxygen species, which, from previous studies, are known to be generated by inflammatory cells. The development of therapeutic modalities directed at the prevention of damage produced by hydrogen peroxide and other oxidant species may be of benefit in reducing corneal endothelial cell damage secondary to ocular inflammatory disease processes.     

Asynergy of right ventricular wall motion in man

Canine studies have shown a correlation between instantaneous segmental lengths in the right ventricular free wall and chamber volume, pressure, and stroke work. To determine whether such correlations exist in intact man, we studied the temporal relationships between chord dynamics in various regions of the right ventricle in 21 heart transplant recipients with apparently normal right ventricular function. Patients were examined by biplane radiography while performing various maneuvers (e.g., Valsalva maneuver). Computer-aided analysis of biplane radiograms of five surgically inserted radiopaque tantalum right ventricular myocardial markers was used to calculate interpoint chord lengths at 33 msec sampling intervals. Two patterns of right ventricular chord asynergy were defined: (1) An akinetic chord had an amplitude of less than 2.0 mm during the course of at least one beat; (2) an out-of-phase chord was more than a quarter period out of phase from the average curve (derived from all concurrently measured marker pairs during each maneuver) for at least one beat. Considering all chords (n = 978), 60 chords (6.1%) were akinetic and nine chords (0.9%) were out of phase. Excluding the outflow tract markers (n = 581), 33 chords (5.7%) were akinetic and five chords (0.9%) showed out-of-phase movement. During some maneuver, at least one akinetic chord occurred in 57% of patients and out-of-phase chords in 33% of patients. Most right ventricular regions were implicated in asynergic motion, including the right ventricular free wall, acute margin, and outflow tract. The frequency and distribution of asynergy in right ventricular chord dynamics observed in this study suggests that changes in a single right ventricular dimension may not accurately reflect global right ventricular events.     

Mechanism of platelet interference with measurement of lactate dehydrogenase activity in plasma

Platelets reportedly inhibit lactate dehydrogenase activity in plasma under reaction conditions of low osmolality. We describe observations inconsistent with these reports, and we attribute this "inhibition" to optical interference by platelets during the course of a reaction. We conclude that when platelet lysis is prevented and the optical interference of platelets corrected, platelet-rich plasma, platelet-poor plasma, and serum show essentially the same lactate dehydrogenase activity. Furthermore, platelet contamination can cause unexpected problems when lactate dehydrogenase is assayed with centrifugal analyzers. Results can be high or low, depending on the volume of diluent pipetted with the sample, and extreme within-run variations in activity are possible. When plasma is used instead of serum for routine analyses, regular checks for platelet contamination should be performed as a quality-control procedure, especially by laboratories separating plasma with bench-top centrifuges. Platelets can also interfere optically with assay of other enzymes and metabolites.     

Stroke Risk among Chinese Immigrants in New York City

Background: Little is known of risk factors for stroke among Chinese immigrants to the United States. We have conducted a case–control study to identify risk factors for stroke among foreign-born Chinese in New York City. Methods: From September 2000 to June 2003, 187 sequential stroke cases (44 hemorrhagic) and 204 controls matched on age, gender, and years since immigration were recruited from New York Downtown Hospital, which was located next to New York City Chinatown. Risk factor status was assessed by questionnaire interview and medical chart review, which included clinical factors, sociodemographic characteristics, personal and family histories, and behavior and lifestyle factors, as well as behavioral changes after immigration to the United States. Results: For cases and controls, mean ages were 74.8 and 74.7 years, 47.3% of cases and 47.5% of controls were male, and mean years since immigration to the United States were 26.7 and 26.8, respectively. Sociodemographic characteristics and behavioral pattern including cigarette smoking, exercise, and usage of special diet or dietary supplements were similar between cases and controls. However, stroke patients were more likely to have hypertension (76% vs. 59%, p≤0.001), increased blood pressure (165/84 mmHg vs. 140/74 mmHg, p≤0.001) and left ventricular hypertrophy (LVH) (10.1% vs. 4.3%, p≤0.05), and less likely to consume poultry (odds ratio 0.80, 95% confidence interval (CI) 0.59–1.00); fish (0.70, 95% CI 0.42–0.96), fruit and vegetable juice (0.83, 95% CI 0.70–0.95), and grains (0.79, 95% CI 0.62–0.96) than were controls. Conclusion: Among Chinese immigrants in New York City, as in general population, poor controlled hypertension was related to the risk of stroke. Therefore, Chinese immigrants presenting with hypertension and/or a family history of hypertension should be detected and followed up regularly to monitor the blood pressure level. In addition, difference in food intake between stroke and control patients may present an opportunity for behavior intervention to prevent stroke.     

Meeting report on the Bellagio Conference 'prevention of vascular diseases in the emerging world: An approach to global health equity'

Representatives from five international organizations (International Society of Nephrology, World Heart Federation, International Diabetes Federation, International Atherosclerosis Federation, and International Society of Hypertension) participated in a strategic planning workshop in December 2005 in Bellagio, Italy sponsored by the Rockefeller Foundation. There were equal representatives from developed and developing countries. Global perspectives on diabetes and cardiovascular and renal diseases were presented, with special emphasis on China, India, Latin America, and Africa. The rationale and effectiveness of preventive measures were discussed. It was apparent that measures for primary prevention and early intervention for all the chronic vascular diseases are similar. The five organizations agreed that an integrated global approach to chronic vascular diseases is needed. They resolved to collaborate and work towards an integrated approach to chronic vascular diseases with the establishment of a 5-year plan for the prevention and treatment of chronic vascular diseases, including public advocacy, advising international and national agencies, and improving education and the practice of established approaches.