Vitamin D deficiency is associated with poor outcomes and increased mortality in severely ill patients.

BACKGROUND: Vitamin D plays a seminal role in many homeostatic mechanisms. In this study, we assessed the correlation between circulating vitamin D levels and mortality rates in critically ill patients. METHODS: All patients admitted to the intensive care units (ICUs) and internal medicine wards in a university-based hospital that required mechanical ventilation were admitted. Data collected included the underlying disease, basic hematological and biochemical blood test results, APACHE II scores and serum 25-hydroxyvitamin D [25(OH)D] levels. The primary end point was defined as all-cause mortality within 60 days from admission or from acute deterioration. RESULTS: Between December 2008 and June 2009, 130 patients were enrolled. Average vitamin D concentration was 14.04 ± 6.9 ng/ml; 107 patients were vitamin D deficient (< 20 ng/ml). Total mortality rate after 60 days was 44.3%. Vitamin D levels were correlated with white blood cell (WBC) count, but with no other measured variable. Among the deceased patients, survival curves indicated that survival of patients with vitamin D deficiency was significantly shorter than those whose vitamin D concentration was >20 ng/ml (P < 0.05); the average survival time was 15.3 ± 12.4 days for vitamin D deficient patients compared with 24.2 ± 16.5 days among those with normal vitamin D levels. CONCLUSION: This study demonstrated that low vitamin D levels are common among patients admitted to ICU. We observed longer survival times among vitamin D sufficient patients. Our results indicate that vitamin D concentration may be either a biomarker of survival or a co-factor. We recommend assessing the effects of vitamin D supplementation in critically ill patients.

Dependence of maternal serum [AFP]/[hCG] median ratios on age of gestation: comparison of trisomy 21 to euploid pregnancies.

BACKGROUND: Current risk calculations for trisomy 21, which are based on multiples of median (MoM), do not take into account possible differences between euploid and trisomy 21 pregnancies that may develop with gestational age. In order to optimize the predictive value of screening tests, we calculated the ratio between maternal serum concentration of alpha-fetoprotein (AFP) and that of human chorionic gonadotropin (hCG) in euploid and in trisomy 21 pregnancies. METHODS: The medians of the concentration ratios, [AFP]/[hCG] at 16-21 weeks of gestation, were plotted as a function of gestational age for 307 cases of trisomy 21 and were compared with the medians of 30 549 normal karyotype cases. RESULTS: [AFP]/[hCG] ratio medians were independent of body weight and maternal age. There was a significant difference in the [AFP]/[hCG] ratio when comparing trisomy 21 and euploid pregnancies at each week. This difference became greater with advancing gestational age (P < 0.01). CONCLUSION: There is a significant difference in ratios of [AFP]/[hCG] between euploid and trisomy 21 pregnancies, which may be used to improve detection rates of Down syndrome screening.

The sensitivity, specificity, and clinical relevance of gel versus tube DATs in the clinical immunology laboratory.

The DAT is a test used to demonstrate in vivo antibody and/or complement coating of RBCs. Typically, the DAT is performed in test tubes; however, recently a number of commercially available tests using gel-filled microtubes have become available. Few data comparing the sensitivity of these test media are available. To compare the rate of detection of a positive DAT performed in test tubes versus in gel-filled microtubes and to assess the clinical significance of the results in patients undergoing evaluation of anemia, we tested 310 consecutive EDTA-anticoagulated blood samples from adult patients. The samples were analyzed using both the conventional tube technique and a gel-based assay (DiaMed; Cressier sur Morat, Switzerland). Test results were expressed as either positive or negative. When a positive result by either technique was encountered, the treating physician was interviewed to determine whether the result warranted further patient investigation or treatment. In 268 out of 310 cases the DAT was negative by both methods. Of the 42 patients with a positive DAT, the test was positive by both methods in 18 patients. In the remaining 24 cases the DAT was positive by the gel test only. In all cases positive by both techniques the test result affected patient management. Of the 24 cases that were positive only by gel test, 3 were judged to be clinically significant. In this study, the gel test was more sensitive than the tube technique for performance of the DAT. However, the clinical significance of a DAT positive only by a gel test is doubtful. We believe that use of the gel-based DAT should be more extensively evaluated before it is adopted as a standard technique in general clinical laboratory practice.

The glycosylphosphatidylinositol-anchored form and the transmembrane form of CD58 are released from the cell surface upon antibody binding.

The adhesion molecule CD58 is expressed on the cell surface in both a transmembrane form and a glycosylphosphatidylinositol (GPI)-anchored form. Here we report that CD58 is released from JY cells following cross-linking by immobilized anti-CD58 monoclonal antibodies. Antibodies to other cell surface proteins, as well as PMA and LPS, did not trigger CD58 release. The release resulted from membrane cleavage, since biotin-labeled CD58 was released from biotinylated cells, and down-modulation of CD58 surface expression accompanied accumulation of soluble CD58 IN culture media. We have previously reported the isolation of JY variant cells, which lack expression of GPI anchored proteins and thus express only the transmembrane form of CD58. Here we show that these variant cells release CD58 upon crosslinking, indicating that the transmembrane isoform is released, probably by proteolysis. Antibodies directed to the cytoplasmic domain of CD58, in contrast to antibodies against an extracellular epitope of CD58, did not react with released CD58, supporting a membrane cleavage mechanism. It is also shown that CD58, released from [3H]ethanolamine-labeled JY cells, contained ethanolamine. This result demonstrated that the GPI-anchored CD58 can be released in parallel to the transmembrane isoform and that this release does not result from proteolytic cleavage, since cleavage by a protease would have removed the ethanolamine. The present data suggest that the two isoforms of CD58 are released upon antibody binding and that their release is mediated by distinct mechanisms.

The glycosylphosphatidylinositol-anchored form and the transmembrane form of CD58 associate with protein kinases.

The significance of the glycosylphosphatidylinositol (GPI) anchor is unknown. Since GPI-anchored proteins mediate signaling, it has been suggested that the GPI structure serves as a signal-transducing element. However, the division of signaling functions between transmembrane and GPI-anchored proteins is unclear. Studies of distinct membrane-anchored forms of the same protein may resolve this issue. The adhesion molecule CD58 is expressed on the cell surface in both a transmembrane and a GPI-anchored form and hence provides a useful model. We studied CD58 in the human B lymphoblastoid cell line JY. In addition to mediating adhesion, CD58 is involved in signal transduction. Incubation of JY cells with immobilized anti-CD58 Abs results in extensive tyrosine phosphorylation and in secretion of TNF-alpha. We demonstrate that CD58 is associated with protein kinase(s) and with several kinase substrates. We further demonstrate that both CD58 isoforms are involved. CD58 in JY variant cells, which express only the transmembrane form, as well as CD58 in JY variant cells, which express only the GPI-anchored form, are associated with kinase activity. This association results in a phosphorylation pattern that is common to the variant and to wild-type JY cells. Thus, these findings suggest that the capacity of GPI-anchored proteins to interact with kinases is not always dependent on the GPI anchor itself.

Persistent measles virus infection enhances major histocompatibility complex class I expression and immunogenicity of murine neuroblastoma cells.

The effect of persistent measles virus infection on the expression of major histocompatibility complex (MHC) class I antigens was studied. Mouse neuroblastoma cells C1300, clone NS20Y, were persistently infected with the Edmonston strain of measles virus. The persistently infected cell line, NS20Y/MS, expressed augmented levels of both H-2Kk and H-2Dd MHC class I glycoproteins. Activation of two interferon(IFN)-induced enzymes, known to be part of the IFN system: (2'-5')oligoadenylate synthetase and double-stranded-RNA-activated protein kinase, was detected. Measles-virus-infected cells elicited cytotoxic T lymphocytes that recognized and lysed virus-infected and uninfected neuroblastoma cells in an H-2-restricted fashion. Furthermore, immunization of mice with persistently infected cells conferred resistance to tumor growth after challenge with the highly malignant NS20Y cells. The rationale for using measles virus for immunotherapy is that most patients develop lifelong immunity after recovery or vaccination from this infection. Patients developing cancer are likely to have memory cells. A secondary response induced by measles-virus-infected cells may therefore induce an efficient immune response against non-infected tumour cells.