Variability of coronary blood flow measurements with microspheres in the rat: role of injection site and sphere number

Although fully explored in larger animals, the role of injection site and sample microsphere content on variability of coronary blood flow (CBF) measurement using the microsphere technique remains controversial in rats despite the fact that this species is extensively used in cardiovascular research. We therefore investigated these variables in two studies. In a first study, we established that the precision of the method, assessed by the variability of four simultaneous CBF determinations, was a function of the sample microsphere number. Coefficient of variation (CV) averaged 4-10% when the tissue and reference samples received greater than 1000 and greater than 100 spheres, respectively, and did not improve appreciably with larger numbers of microspheres. In a second study, flow CV was measured following left atrial (LA) or left ventricular (LV) microsphere injections performed nearly simultaneously in the same conscious animal or in two similar groups of animals. CBF variability was lower by 22-62% after LA than after LV injections. Estimates obtained from separate analysis of the main variability components indicated that, with one exception, the variability associated with LV injections was at least 1.4 to 2.8 times higher than that due to LA injections. These findings establish the minimum number of microspheres needed to obtain precise blood flow determinations in the rat model and confirm previous reports, in anaesthetised rats, that LA microsphere injections generally yield more precise coronary blood flow determinations than LV injections.     

The nonutility of chest roentgenographic examination in asymptomatic patients with positive tuberculin test results

To determine the value of chest roentgenograms in the management of asymptomatic persons with positive tuberculin skin test results, we undertook a retrospective review of all tests administered by our Employee Health Service, North Shore University Hospital, Manhasset, NY, between July 1, 1983 and November 1, 1987. Of 5200 tests, 247 results were positive. Two hundred twenty-one of these charts were reviewed for roentgenographic results and the presence of symptoms. All persons were asymptomatic. Chest roentgenograms revealed the following: normal, 188; unrelated abnormalities, 24; apical pleural thickening, 5; granulomas, 2; calcified hilar node, 1; and calcified node plus granuloma, 1. We noted no active tuberculosis, nor did the chest roentgenographic results influence recommendations for isoniazid prophylaxis. We conclude that chest roentgenograms are of value in 0% to 1.3% of asymptomatic people with positive tuberculin test results. A larger study should be undertaken to further define the usefulness of chest roentgenograms in this population.     

Identifying nursing research priorities: a first step in program development

This study determined nursing research priorities and focused on the development of a nursing research program within a single institution. Of the 715 nurses within the Department of Nursing, 286 (40%) responded to the first round of a two-round Delphi technique, and 137 (48%) responded to the second. The following clinical priorities were determined: prevention and treatment of pressure sores, pain management, treatment of nosocomial infections, and patient education. Nonclinical priorities included staffing and its effects on turnover and patient care, job satisfaction, and factors influencing the quality of nursing care. Serendipitous findings underscored the relevance of the Department of Nursing's conceptual framework to nursing practice and research, revealed the need for dissemination of current research results, and suggested that nurses want to participate in research without assuming responsibility beyond their expertise.     

Pineal activity during the seasonal gonadal cycle in a wild avian species, the tree pie (Dendrocitta vagabunda)

The aim of the present investigation was to study the pineal activity during the seasonal gonadal cycle in both sexes of the Indian tree pie (Dendrocitta vagabunda). The findings revealed that the nuclear diameter of the pineal parenchymal cells moderately decreased and was followed by a moderate increase in the cell population density (per microscopic field of the pineal sections) and serotonin content of the gland during the progressive phase. The values of these parameters were further altered (decreased nuclear diameter with increased cell population density and serotonin level) during breeding but were reversibly altered to some extent during the regression phase, and further altered during the nonbreeding phase in both sexes of the birds. It is suggested that the pineal activity distinctly varies with the seasonal gonadal cycle, being minimum during breeding and maximum during nonbreeding in both sexes of the tree pie.     

Beta-2 microglobulin and amyloid osteoarthropathy in patients undergoing chronic hemodialysis

The incidence of beta-2 microglobulin amyloidosis was assessed in two populations of chronic hemodialysis patients. Out of 34 patients who underwent biopsy during orthopedic surgery (33 cases) or autopsy (1 case), 26 had amyloid deposits which fixed anti-beta microglobulin serum. Out of 55 unselected patients treated for over months at the dialysis centre, 14 (25%) had clinical symptoms suggesting amyloidosis and out of 43 patients who had a systematic radiological skeletal survey, 23 (53%) had bone deposits. The plasma beta microglobulin concentrations (about 20 times the normal value) we not significantly different whether or not the patients had histological proven amyloidosis, clinically or radiologically probable amyloidosis, no detectable amyloidosis. However, the duration of hemodialysis was longer in those with proven or highly probable amyloidosis. The finding illustrate the indirect role of elevation of beta-2 microglobulin in the genesis of this pathology and also the necessity of lowering its concentration in order to avoid the long term complications of osteoarticular deposits, the functional consequences of which may be very serious.     

Antibodies to the ADP/ATP carrier, an autoantigen in myocarditis and dilated cardiomyopathy, penetrate into myocardial cells and disturb energy metabolism in vivo

We identified the ADP/ATP carrier, located within the inner mitochondrial membrane, to be an organ- and conformation-specific autoantigen in myocarditis and dilated cardiomyopathy. We also showed that autoantibodies to the ADP/ATP carrier inhibit the nucleotide transport in vitro. Specific binding of the autoantibodies to the carrier was demonstrated by radioimmunoassay and the immunoblot technique; the inhibition of the nucleotide transport was determined by the inhibitor stop method. To establish if these autoantibodies might also affect cardiac energy metabolism in vivo, we measured whether they are capable of penetrating into myocytes and whether subcellular ATP/ADP ratios and phosphorylation potentials of ATP change in hearts of guinea pigs that have been immunized with the isolated ADP/ATP carrier. An intracellular deposition of autoantibodies was observed by direct immunofluorescence and by immunoperoxidase staining on cryosections of the myocardial tissue of animals immunized with the ADP/ATP carrier. Furthermore, binding of autoantibodies to mitochondrial membrane structures was shown by immunoelectron-microscopic methods. The cytosolic and intramitochondrial distribution of adenine nucleotides in stimulated, isolated perfused hearts of guinea pigs immunized with the ADP/ATP carrier was measured by nonaqueous fractionation. Compared with controls performing equal external heart work, the cytosolic ATP decreased in the immunized animals, whereas the mitochondrial ATP increased strongly; ADP concentrations showed an opposite change. Thus, a resultant cytosolic decrease and a marked mitochondrial increase of the ATP/ADP ratio was established. As a consequence, the cytosolic-mitochondrial phosphorylation potential of ATP was diminished. These findings demonstrate that antibodies against intracellular antigens are able to penetrate into living cells, and that autoimmunity to the ADP/ATP carrier may contribute to the pathophysiology of myocarditis and dilated cardiomyopathy by causing an autoantibody-mediated imbalance between intracellular energy delivery and demand.     

Lyme arthritis

Evanescent arthralgias and myalgias are common early symptoms of Lyme disease. Transient, intermittent episodes of monoarticular, oligoarticular, or sometimes migratory polyarticular arthritis, lasting weeks to months, with disease-free intervals, are frequently observed in untreated patients with erythema chronicum migrans. A minority of patients develop chronic joint involvement, most commonly affecting the knee. Antibiotic therapy given during erythema chronicum migrans is often protective with regard to late joint manifestations. In chronic Lyme arthritis, however, the response to antibiotics is variable.