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Abstract
Pulmonary surfactant is a multimolecular complex located at the air-water interface within the alveolus to which a range of physical (surface-active properties) and immune functions has been assigned. This complex consists of a surface-active lipid layer (consisting mainly of phospholipids), and of an aqueous subphase. From discrete surfactant sub-fractions one can isolate strongly hydrophobic surfactant proteins B (SP-B) and C (SP-C) as well as collectins SP-A and SP-D, which were shown to have specific structural, metabolic, or immune properties. Inborn or acquired abnormalities of the s u rfactant, qualitative or quantitative in nature, account for a number of human diseases. Beside hyaline membrane disease of the preterm neonate, a cluster of hereditary or acquired lung diseases has been characterized by periodic acid-Schiff-positive material filling the alveoli. From this heterogeneous nosologic group, at least two discrete entities presently emerge. The first is the SP-B deficiency, in which an essentially proteinaceous material is stored within the alveoli, and which represents an autosomal recessive Mendelian entity linked to the SFTPB gene (MIM 1786640). The disease usually generally entails neonatal respiratory distress with rapid fatal outcome, although partial or transient deficiencies have also been observed. The second is alveolar proteinosis, characterized by the storage of a mixed protein and lipid material, which constitutes a relatively heterogeneous clinical and biological syndrome, especially with regard to age at onset (from the neonate through to adulthood) as well as the severity of associated signs. Murine models, with a targeted mutation of the gene encoding granulocyte macrophage colony-stimulating factor (GM-CSF) ( Csfgm ) or the β subunit of its receptor ( Il3rb1 ) support the hypothesis of an abnormality of surfactant turnover in which the alveolar macrophage is a key player. Apart from SP-B deficiency, in which a near-consensus diagnostic chart can be designed, the ascertainment of other abnormalities of surfactant metabolism is not straightforward. The disentdisentanglement of this disease cluster is however essential to propose specific therapeutic procedures: repeated broncho-alveolar lavages, GM-CSF replacement, bone marrow grafting or lung transplantation.
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June 1, 2005
Abstract
Impaired trace element metabolism may be involved in some of the metabolic dysfunctions, and contribute to the development of vascular complications in diabetic patients. In order to investigate the relationships among diabetes mellitus, trace element status, leukocyte activation and vascular complications, 55 type 2 diabetic patients (34 with vascular complications and 21 without vascular complications) and 50 non-diabetic control subjects were studied. The mean leukocyte count (p<0.001), polymorphonuclear elastase (p<0.001), erythrocyte malondialdehyde (p<0.001), and glycated haemoglobin (p<0.001) levels, and copper/zinc ratio (p<0.001) were found to be higher in diabetic patients than in the control group, but serum zinc levels (p<0.001) and erythrocyte superoxide dismutase activities (p<0.001) were lower, and serum copper levels showed no differences. In patients with vascular complications, the mean leukocyte count (p<0.05), zinc (p<0.05), polymorphonuclear elastase (p<0.05), erythrocyte malondialdehyde (p<0.001) and glycated haemoglobin (p<0.05) levels, and copper/zinc ratio (p<0.001) were significantly different from those patients without complications. Closer correlations between the copper/zinc ratio and polymorphonuclear elastase (r=0.82, p<0.01), erythrocyte malondialdehyde (r=0.46, p<0.05) or erythrocyte superoxide dismutase (r= −0.85, p<0.01) were found in patients with vascular complications compared to those without, and all of those showed significant relationships with poor glycaemic metabolic control. We conclude that zinc deficiency may provoke polymorphonuclear leukocyte activation, and contributes to the development of vascular complications in type 2 diabetic patients. Furthermore, copper/zinc ratio and polymorphonuclear elastase may be used as important markers to evaluate the presence of vascular complications.
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June 1, 2005
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We evaluated the analytical performance and diagnostic utility of complexed prostate-specific antigen (CPSA) and their ratios, complexed-to-total PSA (C/T PSA) and free-to-complexed PSA (F/C PSA), in comparison with the total PSA (TPSA) and free-to-total PSA ratio (F/T PSA) as means of diagnosing prostate cancer (PC). Samples (n=101) were drawn from men with no evidence of malignancy (n=80) and from men with PC (n=21) at biopsy. For determination of the F/T PSA ratio, the DPC ® Immulite-2000 method was used; and the Bayer ® Immuno-1 CPSA and TPSA assays were used to determine the C/T PSA ratio. The Bayer ® Immuno-1 CPSA assay provides accurate and precise CPSA values in human serum. The performance of the different forms and ratios was compared using receiver operating characteristic curve analysis. CPSA had the greatest area under the curve (AUC, 0.689) although it was not statistically different from the other parameters. A cut-off value of 4.66 ng/ml for CPSA provided a specificity of 38% and a sensitivity of 93%. The F/C PSA ratio maintained a sensitivity of 93% and had an increased specificity of 41%. The measurement of CPSA provides a slight increase in specificity compared with the use of the TPSA in the early detection of prostate cancer.
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June 1, 2005
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Aberrant DNA methylation has been identified as an important mechanism for inactivation of tumor suppressor genes and mismatch repair genes during carcinogenesis. We used b̲i̲sulfite treatment and the P̲CR s̲ingle strand conformation polymorphism (S̲SCP) (BiPS) technique to analyze methylation status of the promoter regions of the hMLH1 , p16 , and HIC1 genes in several cancer cell lines and colorectal cancer tissues. The methylation of the hMLH1 , p16 and HIC1 genes was observed in 2, 8, and 13 of 13 cancer cell lines, respectively. The SSCP for p16 and HIC1 in each of the methylation-positive cell lines were similar, indicating relative homogeneity of methylation status and complete methylation in the cell lines. Methylation was observed in 8, 5, and 21 of 25 colorectal cancer tissues for the hMLH1 , p16 , and HIC1 genes, respectively. The methylated bands revealed by BiPS analysis of the hMLH1 gene were homogeneous, whereas those of the p16 and HIC1 genes were different in each case. The methylation of the promoter region of the HIC1 gene in colorectal cancer was observed most frequently and could serve as a sensitive marker for colorectal cancer. Methylation status of the hMLH1 and p16 gene promoters was correlated with microsatellite instability status, tumor location, and differentiation but not with K- ras mutation or allelic loss of p53 .
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June 1, 2005
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The changes in serum levels of serum amyloid A protein were studied in 67 patients suffering from colorectal carcinoma and compared to three other major acute phase proteins: C-reactive protein, α 1 -antichymotrypsin and α 1 -acid glycoprotein. Although the presence of colorectal carcinoma caused an increase in serum levels of all the acute phase reactants studied, serum amyloid A protein showed the most powerful reaction in pre-operative disease stage, with the mean value of 330 mg/l (range 7–2506 mg/l) as compared to the normal values of <1.2 mg/l obtained in 30 healthy adults. The mean serum amyloid A protein concentration increased to 487 mg/l after surgery, declining during the post-operative clinical course until the sixth chemotherapy cycle (from 167mg/l to 64 mg/l), but never returned to the normal range. In the later chemotherapy cycles, mean serum amyloid A protein increased to 163 mg/l, probably as a result of the disease relapse. According to the statistical relations among exact confidence intervals for proportions, serum amyloid A protein showed the best specificity for colorectal carcinoma of all the acute phase proteins studied (83–100%) and also a sensitivity of 100%. We concluded that serum amyloid A protein seems to be a reliable parameter, which could be recommended for clinical routine as a non-specific tumour marker for colorectal carcinoma.
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June 1, 2005
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Twenty-seven consecutive patients with health problems associated with dental amalgam were recruited. In spite of thorough medical examinations, there were no diagnoses available. The patient group was dominated by women. A healthy age- and sex-matched control group with dental amalgams without symptoms was also recruited. Metal level monitoring in plasma and nuclear microscopy of isolated individual blood cells were carried out. Significant increases of copper, iron, zinc and strontium were found in patient plasma. There was no significant difference in plasma selenium between the groups. Mercury was significantly increased in patient plasma, although there was overlap between the groups. In erythrocytes a significant increase in calcium and a significant decrease in magnesium, copper, manganese and zinc were found. Calcium, magnesium, manganese and copper increased in patient neutrophil granulocytes. A significant decrease was found for zinc. A conspicuous finding was the presence of measurable mercury in a few of the cells from the patient but not in the control group. Thus, nuclear microscopy of isolated individual blood cells might provide a better diagnostic tool for metal exposure than blood plasma measurements.
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June 1, 2005
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Some mechanisms have been proposed for cataract formation in diabetes mellitus such as excessive tissue sorbitol concentrations, abnormal glycosylation of lens proteins and increased free radical production in the intraocular region. We measured total antioxidant status and uric acid levels in aqueous humor from diabetic (n=20) and non-diabetic subjects (n=16) with cataracts. The patients with diabetes and cataract had significantly lower aqueous humor total antioxidant status than those with senile cataract (p = 0.001). Serum and aqueous humor uric acid levels were significantly lower in the diabetic cataract group compared to the senile cataract group. In the diabetic cataract group, the aqueous humor antioxidant status correlated positively with the aqueous humor uric acid levels (p < 0.05). The results of this study suggest that reduced aqueous humor antioxidant status might be associated with reduced aqueous humor uric acid in patients with diabetic cataract. This decrease in aqueous humor uric acid levels might lead to the acceleration of cataract formation.
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June 1, 2005
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A multilocus assay was used to genotype up to 27 variable sites in 15 genes in French and Italian, presumed to be healthy populations (n=1480, n=162, respectively). These genes are involved in lipid metabolism ( APOE, APOB, APOC3, CETP, LPL, PON ), homocysteine metabolism ( CBS, MTHFR ), blood viscosity ( Fibrinogen, FV ), platelet aggregation ( GpIIIa ), leukocyte adhesion ( SELE ), and renin-angiotensin system ( AT1R, ACE, AGT ). Allele frequencies for all the markers were compared between the two populations. Five allele frequencies differed between the two European countries: APOB 71Ile (p ≤0.001), SELE 98T (p ≤ 0.001), SELE 128Arg (p ≤0.01), APOE ∈4 (p ≤ 0.01) and MTHFR 677T (p ≤0.01), suggesting the existence of a north-south gradient in European allele frequencies. The other allele frequencies : APOC3 −482T, −455C, 1100T, 3175G, 3206G; LPL −93G, 9Asn, 291Ser; CETP 405Val; PON 192Arg ; ACE Del; AGT 235Thr; AT1R 1166C; CBS 278Thr, GpIIIa P1 A2 ; Fibrinogen −455A, FV 506Gln and SELE 554Phe, were similar between the two populations. They were also similar to those observed in other European countries.
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In blood, the exopeptidase dipeptidyl-peptidase IV (DPPIV; EC 3.4.14.5) is predominantly present in a soluble form in plasma/serum and as an activation antigen on the membrane of lymphocytes (CD26). It modifies some important biologically active peptides (neuropeptides, chemokines), and a regulatory role for DPPIV/CD26 in immune and endocrine processes has been demonstrated. The aim of this study was to determine reference values for plasma/serum DPPIV activity and to study the association of this activity with a series of biochemical and hematological parameters and baseline characteristics such as age, gender, blood pressure and body mass index. We studied 481 healthy subjects aged between 19 and 61 years. The group consisted of 213 men and 268 women equally divided between the different categories of age. Among the women, 127 were taking hormone therapy (contraception/hormone replacement) and 141 were not. A multiple regression model shows that DPPIV activity decreases significantly with age. The activity in women is slightly lower than in men. We observed an important association with liver, muscle and lipid metabolism-related parameters. In this model, no significant contribution of body mass index, blood pressure or hormone therapy could be stated.
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June 1, 2005
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The index of individuality is defined as the ratio of the within-subject biological variation to the between-subject variation, i.e. , the variation between the biological set-points. It has been disputed whether the index of individuality has influence on the usefulness of conventional population-based reference intervals. In this investigation we found that, as long as only a single sample is taken, for a certain change in an individual's set-point, the index of individuality has no influence on the usefulness of reference intervals. When two or more samples are taken into account, however, the outcome of the measurement is highly dependent on the index of individuality. For a low index, repeat measurement has only limited effect on the fraction of false-positive results, as the next result will be close to the first, but, when the index is high, the fraction of false-positive results will be reduced considerably through repeating the test. Moreover, the distribution of biological set-points for which the fraction of false-positive results originate is described and the influence of analytical imprecision is discussed. The calculations are performed for values of the index of individuality from 0 to 2.0 for the traditional 95% reference interval based on x̄ ± 2*s total (s total = total biological variation), and also for a decision limit (cut-off point) x̄ ± 3*s total . The numbers are, of course, different, but the effects of the index of individuality are the same, independent of the chosen cut-off point. This concept is related to the clinical classification (diagnosis, prognosis, screening) and the difference from different principles of monitoring is discussed. Further, five examples are evaluated and aspects of index of individuality in relation to false-positive results are discussed.
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This work is a model of co-operation between the in vitro diagnostic industry and clinical laboratories for the production of reference values. Thirteen clinical laboratories having an ADVIA Centaur analyser and representing the majority of the geographical regions of Spain have shared the search for reference individuals and the production of reference values for thyrotropin, free thyroxine, free triiodothyronine, cobalamine and folate concentrations in serum. All the logistic work has been done in co-operation with the Spanish supplier of the ADVIA Centaur analyser. The reference limits produced in the virtual laboratory are derived from the blend of reference values obtained by each laboratory. The multicentre reference limits were estimated according to the recommendations of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC).
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July 27, 2005
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The objective of this report is to help to improve the quality of immunochemical determinations of cardiac troponins. The guidelines are intended for use by the manufacturers of commercial assays and by clinical laboratories performing troponin analyses. The main goals of the document are that: 1. Manufacturers endorse, or at the minimum, address the enclosed recommendations. 2. All package inserts for troponin immunoassay procedures include information on method design, and on pre-analytical and analytical performance characteristics as outlined in this document. 3. Manufacturers and the scientific community select and design research projects that further the knowledge and the definition of the issues addressed in this document.
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