Clinical Abstracts
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Clinical Abstracts |
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August 2005
Editors:
Inflammatory markers in sarcoidosis Inflammatory markers in sarcoidosis Pulmonary sarcoidosis, the second most common respiratory disease after asthma in young adults, is characterized by a hyperimmune response to an unknown agent at lesion sites. Inflammatory stimuli in sarcoidosis generally lead to activation of monocyte-macrophages, which in turn produce cytokines—for example, tumor necrosis factor-a and interleukin-1 (IL1) and IL6. Consequently, IL1 and IL6 concentrations increase and stimulate hepatic production of acute-phase proteins such as C-reactive protein (CRP) and serum amyloid A (SAA). In sarcoidosis, inflammation leads to granuloma formation. Angiotensin-converting enzyme (ACE) is a product of granuloma (of epithelioid cells that are derivatives of the activated macrophages). Despite its shortcomings, ACE is mostly used in the assessment and follow-up of sarcoidosis. The authors conducted a study to determine the diagnostic accuracy of soluble interleukin-2 receptor (sIL2R), ACE, high-sensitivity CRP (hs-CRP), and SAA to predict the severity of pulmonary sarcoidosis as indicated by pulmonary function testing. From the 185 sarcoidosis patients who visited the authors' sarcoidosis management center between 1999 and 2002, the authors selected 144 nonsmoking patients: 73 untreated (group one) and 71 treated (group two). Subgroups of the untreated patients (group Ia [nonchronic group with time since diagnosis of two years or less] and group Ib [chronic group with time since diagnosis of more than two years]) were evaluated separately. Receiver operating characteristic curves and logistic regression analyses were used to compare the diagnostic accuracy of different markers to assess disease severity. Pulmonary disease severity was defined by lung function test results. The authors found that in untreated subgroup Ia and the total untreated group (group one), sIL2R had the largest areas under the curve (0.891 and 0.799, respectively) and the highest sensitivity (82 percent and 64 percent), specificity (94 percent and 88 percent), and positive (82 percent and 70 percent) and negative (94 percent and 88 percent) predictive values among the evaluated markers in both untreated groups. Nevertheless, the confidence intervals for sIL2R area under the curve, sensitivity, and specificity were broad and partly overlapped those of ACE, hs-CRP, and SAA. In the treated group (group two), all four markers appeared to have comparable AUCs, ranging from 0.645 for SAA to 0.711 for sIL2R. The authors concluded that sIL2R appears to be useful for monitoring respiratory disease severity in sarcoidosis, and they recommend sIL2R measurement in the follow-up of patients with sarcoidosis. Rothkrantz-Kos S, van Dieijen-Visser MP, Mulder PGH, et al. Potential usefulness of inflammatory markers to monitor respiratory functional impairment in sarcoidosis. Clin Chem. 2003;49:1510-1517. Reprints: Marja P. van Dieijen-Visser, University Hospital of Maastricht, Dept. of Clinical Chemistry, P.O. Box 5800, 6202 AZ Maastricht, Netherlands; dieijen@klinchem.azm.nl Use of myeloperoxidase as a cardiac marker Coronary thrombosis results in serious adverse cardiac events, even with aggressive intervention and treatment. Levels of creatine kinase isoenzymes and cardiac troponins, which are diagnostic biologic markers of myocardial necrosis, are used alone or in conjunction with levels of C-reactive protein as prognostic indicators of myocardial infarction. Many patients with chest pain have normal levels of creatine kinase isoenzymes or troponins at presentation but subsequently have a myocardial infarction, require revascularization, or die within six months. Additional biochemical measures, ideally based on the pathophysiology of plaque vulnerability, are needed. Inflammation has been linked to all stages of the development of vulnerable plaque, from initial lipid deposition to plaque rupture and its thrombotic complications. Evidence of leukocyte activation and degranulation is found in patients with unstable angina, and extensive monocyte and neutrophil infiltration is seen in fissured, thrombosed plaques in patients with acute coronary syndromes. In vitro studies suggest numerous mechanisms through which leukocytes may affect the stability of plaque in acute coronary syndromes. One potential participant is the leukocyte enzyme myeloperoxidase. The authors assessed the value of plasma levels of myeloperoxidase as a predictor of the risk of cardiovascular events in 604 sequential patients presenting to the emergency department with chest pain. Initial plasma myeloperoxidase levels predicted the risk of myocardial infarction, even in patients who were negative for troponin T (<0.1 ng/mL) at baseline (P<0.001). Myeloperoxidase levels at presentation also predicted the risk of major adverse cardiac events—myocardial infarction, the need for revascularization, or death—within 30 days and six months after presentation (P<0.001). In patients without evidence of myocardial necrosis (defined as those who were negative for troponin T), the baseline myeloperoxidase levels independently predicted risk of major adverse coronary events at 30 days (unadjusted second, third, and fourth quartile odds ratios, 2.2 [95 percent confidence interval, 1.1 to 4.6], 4.2 [95 percent confidence interval, 2.1 to 8.4], and 4.1 [95 percent confidence interval, 2.0 to 8.4], respectively) and at six months. The authors concluded that a single initial measurement of plasma myeloperoxidase independently predicts early risk of myocardial infarction as well as risk of major adverse cardiac events in the ensuing 30-day and six-month periods. Myeloperoxidase levels, in contrast to troponin T, creatine kinase MB isoform, and C-reactive protein levels, identify patients at risk for cardiac events in the absence of myocardial necrosis, highlighting its potential usefulness for risk stratification among patients who present with chest pain. Brennan M-L, Penn MS, Van Lente F, et al. Prognostic value of myeloperoxidase in patients with chest pain. N Engl J Med. 2003;349:1595-1604. Reprints: Dr. Stanley L. Hazen, Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic Foundation, 9500 Euclid Ave., NC10, Cleveland, OH 44195; hazens@ccf.org Mercury contamination of fish oil preparations Epidemiologic studies have shown that the Greenland Eskimos have a comparatively low incidence of coronary artery disease, which has been attributed to their consuming more than 400 grams of fish per day. Presumably, this protection results from the high level of omega-3 polyunsaturated fatty acids (omega-3 PUFAs) in oils derived from deep cold-water fish. This discovery underscores the important role of diet in coronary artery disease (CAD) and has prompted research into the benefits of fish consumption in the general population. A potential issue arises, however, because some fish, such as swordfish and shark, may also contain relatively high levels of toxic heavy metals. Fish intake is a major source of exposure to mercury, primarily methylmercury. Recent studies show that levels of mercury in toenails are directly associated with risk of acute myocardial infarction. One study found no significant correlation between toenail mercury and CAD, but a trend did exist. The association between the amount of fish consumed and mercury levels has been documented. Yet data regarding the cardiovascular benefits of fish have been inconsistent. These conflicting results may be explained by the variable amounts of mercury contained in different fish, which may negate the beneficial effects of omega-3 PUFAs. The authors stated that because fish oils have similar antiatherogenic properties to fish, similar studies should be performed to determine the level of mercury in fish oils. The authors determined the concentration of mercury in five over-the-counter brands of fish oil—CVS, Kirkland, Nordic Ultimate, Omega Brite, and Sundown. The levels of mercury in the five brands of fish oil ranged from non-detectable (<6 µg/L) to negligible (10 -12 µg/L). The mercury content of fish oil was similar to the basal concentration normally found in human blood. The authors concluded that the fish oil brands they examined have negligible amounts of mercury and may provide a safer alternative to fish consumption. Foran SE, Flood JG, Lewandrowski KB. Measurement of mercury levels in concentrated over-the-counter fish oil preparations: Is fish oil healthier than fish? Arch Pathol Lab Med. 2003;127:1603-1605. Reprints: Dr. Kent B. Lewandrowski, Division of Laboratory Medicine, Massachusetts General Hospital, 55 Fruit St., GRJ 5, Boston, MA 02114; klewandrowski@partners.org Placental transfer of anti-rubella antibodies Placental transfer of maternal immunoglobulins is the major route of protection for infants during and after gestation. This active process starts during the first trimester of gestation. The concentration of neonatal IgG, however, does not seem to exceed one-third of maternal IgG at this time. It has been suggested that prematurity, low birth weight, and maternal immunoglobulin concentration may interfere with the materno-fetal transport of antibodies. Consequently, preterm infants may be more vulnerable to viral and bacterial infections. Rubella is an endemic disease in Iran; however, the rubella vaccine is not part of the routine immunization schedule for that country. Therefore, young mothers and their infants depend on the mother's history of previous rubella infection. To assess the degree of rubella immunity in mothers and to what degree this immunity is transferred to newborns, anti-rubella IgG titer was determined in 219 mothers and their full-term and preterm newborns. In total, 231 pregnant women and their paired infants enrolled in this study, of which, 197 gave birth to full-term and 26 gave birth to preterm infants. Rubella-specific antibodies were detected by an in-house, whole-virus, enzyme-linked immunosorbent assay in the maternal and cord sera of 188 full-term and 26 preterm infants. The authors observed a highly significant correlation between anti-rubella IgG in newborns in total, preterm, and full-term neonates with their paired mothers (P= 0.0001, 0.002, 0.0001, respectively). They observed a borderline significant difference between mean anti-rubella IgG in full-term and preterm neonates (P=0.04). Mean cord/maternal ratio of anti-rubella IgG was 0.83, which was surprisingly low. A significantly lower anti-rubella IgG was observed in newborns born from mothers with blood group B+ than those born from mothers with blood groups A+ (P=0.04) and O+ (P=0.02), respectively. The authors noted the same difference between mean maternal anti-rubella IgG in those with blood groups B+ and A+ (P=0.04) and those with blood groups B+ and O+ (P=0.05). In addition, they detected a low frequency of B+ blood group in high positive sera and a high frequency of this blood group in low positive and negative sera. The authors concluded that the main factors that influence an infant’s rubella-specific IgG concentration are maternal concentration of this immunoglobulin, maternal blood group, and neonatal gestational age. Doroudchi M, Dehaghani AS, Emad K, et al. Placental transfer of rubella-specific IgG in fullterm and preterm newborns. Int J Gynaecol Obstet. 2003;81:157-162. Reprints: A. Ghaderi, Dept. of Immunology, Medical School, Shiraz University of Medical Sciences, Shiraz, Iran; ghaderia@sums.ac.ir An algorithm for bovine spongiform encephalopathy Bovine spongiform encephalopathy was first recognized and defined as a pathological entity in the United Kingdom in November 1986. Initial epidemiological investigations and examination of archived brains indicated that the first clinical cases occurred around April 1985. The disease affects adult animals, with a peak age at onset of four to five years. The age range of clinical, confirmed cases is between 20 months and almost 20 years, although bovine spongiform encephalopathy (BSE) is rarely confirmed in animals younger than 30 months. The specific origin of the disease is not clear, but the marker of the disease is the prion protein PrPres. In the late 1970s, a reduction in the use of hydrocarbon solvents in the production of meat-and-bone meal coincided with the accepted start of exposure of the cattle population in Great Britain—the first cases of confirmed BSE were born at the time of this change. Most BSE cases within the cattle population are suspected to result from the recycling of infected cattle tissues via meat-and-bone meal. The duration of clinical signs is on average one to two months, but it can be less than two weeks and as long as a year. BSE can only be confirmed postmortem by pathological examination of brain tissue. The new variant of Creutz feldt-Jakob disease was identified in the United Kingdom in 1996. Several subsequent investigations have indicated a possible link between the disease and BSE. The differential diagnosis of BSE is complex. Reporting of clinically suspected cattle is the most common method for detecting cases of the disease. Improvement of clinical diagnosis and decisionmaking remains crucial. A comparison of clinical patterns, consisting of 25 signs, was made between all 30 BSE cases confirmed in Belgium before October 2002 and 272 suspected cases that were subsequently determined to be histologically, immunohistochemically, and scrapie-associated-fiber negative. Seasonality in reporting suspected cases was observed, with more cases being reported during the winter, when animals were kept indoors. The median duration of illness was 30 days. The 10 most relevant signs of BSE were kicking in the milking parlor, hypersensitivity to touch or sound, or both, head shyness, panic-stricken response, reluctance to enter the milking parlor, abnormal ear movement or carriage, increased alertness, reduced milk yield, teeth grinding, and temperament change. Ataxia did not appear to be a specific sign of BSE. A classification and regression tree was constructed using the features of age, year of birth, number of relevant BSE signs noted, and number of clinical signs, typical for listeriosis, noted. The model had a sensitivity of 100 percent and specificity of 85 percent. The authors concluded that this approach allows the use of an interactive decision-support tool based entirely on odds ratios, a statistic independent of disease prevalence. Saegerman C, Speybroeck N, Roels S, et al. Decision support tools for clinical diagnosis of disease in cows with suspected bovine spongiform encephalopathy. J Clin Microbiol. 2004;42:172-178. Reprints: D. Berkvens, Institute of Tropical Medicine, Dept. of Animal Health, Nationalestraat 155, B-2000 Antwerpen, Belgium; dberkvens@itg.be Human scleroderma autoantibodies and snoRNP Systemic sclerosis is a systemic autoimmune disease characterized by a spectrum of clinical, pathologic, and serologic abnormalities. Between 60 percent and 96 percent of systemic sclerosis (SSc) patients spontaneously produce antinuclear antibodies (ANAs), including diagnostically relevant specificities such as anti-DNA topoisomerase I (anti-Scl-70), anticentromere antibodies, and antifibrillarin. Antifibrillarin antibodies predominate among the antinucleolar antibodies (ANoA) specificities found in SSc, occurring in 12 percent to 48 percent of ANoA-positive patients. To determine whether other protein components of the fibrillarin-associated small nucleolar RNP (snoRNP) complexes are autoantibody targets, the authors tested sera from 220 scleroderma patients for autoantibodies to the U3 snoRNP-specific proteins Mpp10 and hU3-55K. U3-specific proteins were chosen because the U3 snoRNP is the most abundant box C/D snoRNP and is, therefore, the most likely to supply immunogenic/antigenic material that could contribute to autoantibody responses. The authors examined sera from 220 scleroderma patients for ANoAs and for antibodies to fibrillarin and the U3 snoRNP-specific proteins Mpp10 and hU3-55K. Clinical correlates were determined for the different autoantibody specificities. The authors found that 59 of the 220 patients were positive for ANoA, and 31 of these patients were antifibrillarin positive. Anti-hU3-55K was found in 10 patients, all of whom were antifibrillarin positive. Twenty-nine patients had anti-Mpp10 antibodies; 23 of these were antifibrillarin positive and six were antifibrillarin negative. ANoA, including antifibrillarin, anti-hU3-55K, and anti-Mpp10, were associated with diffuse, rather than limited, systemic or localized scleroderma. Esophageal and lung involvement were more common in patients with antifibrillarin and anti-Mpp10 antibodies, and the highest frequency was in patients with anti-Mpp10 alone. The authors concluded that antifibrillarin autoantibodies are associated with autoantibodies to protein components specific to U3 snoRNP, particularly Mpp10. The prevalence of anti-Mpp10 antibodies in antifibrillarin-positive patients suggests that the U3 snoRNP particle is a source of immunogenic/antigenic material for the anti-snoRNP response in sclero derma. Autoantibodies to snoRNP components were more frequent in patients with diffuse scleroderma than in those with the limited systemic or localized forms. The increased expression of these antibodies in patients with the more severe form of sclero derma, coupled with the observations that fibrillarin expression is positively linked to collagen expression in fibroblasts and that fibrillarin is overexpressed in scleroderma fibroblasts, suggests a source of snoRNP to initiate and maintain these autoantibody responses. Yang JM, Hildebrandt B, Luderschmidt C, et al. Human scleroderma sera contain autoantibodies to protein components specific to the U3 small nucleolar RNP complex. Arthritis Rheum. 2003;48:210-217. Reprints: Dr. K. Michael Pollard, W.M. Keck Autoimmune Disease Center, Dept. of Molecular and Experimental Medicine, Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037; mpollard@scripps.edu
Dr. Bissell is professor and director of clinical services and vice chair, department of pathology, Ohio State University Medical Center, Columbus. Dr. Domen is professor of pathology, medicine, and humanities, Penn State University College of Medicine, Hershey, Pennsylvania. |
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