Rationale and design of the Chronic Kidney Disease Antidepressant Sertraline Trial (CAST)

Major Depressive Disorder (MDD) affects one in five patients with Chronic Kidney Disease (CKD) and is an independent risk factor for hospitalization and death before and after dialysis initiation. However, it remains an under-recognized and under-treated problem, in part due to the lack of well-controlled studies that support or refute the efficacy and safety of antidepressant medications in CKD patients. Major trials of antidepressant treatment excluded patients with stages 3–5 CKD, precisely those at higher risk for both depression and increased mortality. The Chronic Kidney Disease Antidepressant Sertraline Trial (CAST) is a randomized, double-blinded, placebo-controlled trial of sertraline, a selective serotonin reuptake inhibitor (SSRI). It will enroll 200 adults with stages 3–5 CKD and MDD excluding kidney transplant and chronic dialysis patients. Sertraline will be administered at an initial dose of 50 mg once daily or matching placebo followed by a dose escalation strategy consisting of 50 mg increments at 2 week intervals (as tolerated) to a maximum dose of 200 mg. The primary outcome is improvement in depression symptom severity measured by the Quick Inventory of Depressive Symptomatology scale. Secondary outcomes include safety endpoints and improvement in quality of life. Changes in cognitive function, adherence to medications, nutritional status, inflammation, and platelet function will be explored as potential mechanisms by which depression may mediate poor outcomes. We discuss the rationale and design of the CAST study, the largest placebo-controlled trial aimed to establish safety and efficacy of a SSRI in the acute phase treatment of CKD patients with MDD.     

Gene conversion is a likely cause of mutation in PKD1

Approximately 70% of the gene responsible for the most common form of autosomal dominant polycystic kidney disease ( PKD1 ) is replicated in several highly homologous copies located more proximally on chromosome 16. We recently have described a novel technique for mutation detection in the duplicated region of PKD1 that circumvents the difficulties posed by these homologs. We have used this method to identify two patients with a nearly identical cluster of base pair substitutions in exon 23. Since pseudogenes are known to be reservoirs for mutation via gene conversion events for a number of other diseases, we decided to test whether these sequence differences in PKD1 could have arisen as a result of this mechanism. Using changes in restriction digest patterns, we were able to show that these sequence substitutions are also present in N23HA, a rodent-human somatic cell hybrid that contains only the PKD1 homologs. Moreover, these changes were also detected in total DNA from several affected and unaffected individuals that did not harbor this mutation in their PKD1 gene copy. This is the first example of gene conversion in PKD1 , and our findings highlight the importance of using gene-specific reagents in defining PKD1 mutations.      

Epigenetic modulation at birth – altered DNA-methylation in white blood cells after Caesarean section

Aim:  Delivery by C-section (CS) has been associated with increased risk for allergy, diabetes and leukaemia. Whereas the underlying cause is unknown, epigenetic change of the genome has been suggested as a candidate molecular mechanism for perinatal contributions to later disease risk. We hypothesized that mode of delivery affects epigenetic activity in newborn infants.
Methods:  A total of 37 newborn infants were included. Spontaneous vaginal delivery (VD) occurred in 21, and 16 infants were delivered by elective CS. Blood was sampled from the umbilical cord and 3–5 days after birth. DNA-methylation was analyzed in leucocytes.
Results:  Infants born by CS exhibited higher DNA-methylation in leucocytes compared with that of those born by VD (p < 0.001). After VD, newborn infants exhibited stable levels of DNA-methylation, as evidenced by comparing cord blood values with those 3–5 days after birth (p = 0.55). On postnatal days 3–5, DNA-methylation had decreased in the CS group (p = 0.01) and was no longer significantly different from that of VD (p = 0.10).
Conclusion:  DNA-methylation is higher in infants delivered by CS than in infants vaginally born. Although currently unknown how gene expression is affected, or whether epigenetic differences related to mode of delivery are long-lasting, our findings open a new area of clinical research with potentially important public health implications.     

Predominance of null mutations in ataxia-telangiectasia

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder involving cerebellar degeneration, immunodeficiency, chromosomal instability, radiosensitivity and cancer predisposition. The responsible gene, ATM, was recently identified by positional cloning and found to encode a putative 350 kDa protein with a Pl 3-kinase-like domain, presumably involved in mediating cell cycle arrest in response to radiation-induced DNA damage. The nature and location of A-T mutations should provide insight into the function of the ATM protein and the molecular basis of this pleiotropic disease. Of 44 A-T mutations identified by us to date, 39 (89%) are expected to inactivate the ATM protein by truncating it, by abolishing correct initiation or termination of translation, or by deleting large segments. Additional mutations are four smaller in-frame deletions and insertions, and one substitution of a highly conserved amino acid at the Pl 3-kinase domain. The emerging profile of mutations causing A-T is thus dominated by those expected to completely inactivate the ATM protein. ATM mutations with milder effects may result in phenotypes related, but not identical, to A-T.      

Bcl‐3 deficiency protects against dextran‐sodium sulphate‐induced colitis in the mouse

Bcl-3 is a member of the IκB family of proteins and is an essential negative regulator of Toll-like receptor-induced responses. Recently, a single nucleotide polymorphism associated with reduced Bcl-3 gene expression has been identified as a potential risk factor for Crohn''s disease. Here we report that in contrast to the predictions of single nucleotide polymorphism (SNP) analysis, patients with Crohn''s disease and ulcerative colitis demonstrate elevated Bcl-3 mRNA expression relative to healthy individuals. To explore further the potential role of Bcl-3 in inflammatory bowel disease (IBD), we used the dextran-sodium sulphate (DSS)-induced model of colitis in Bcl-3^−/− mice. We found that Bcl-3^−/− mice were less sensitive to DSS-induced colitis compared to wild-type controls and demonstrated no significant weight loss following treatment. Histological analysis revealed similar levels of oedema and leucocyte infiltration between DSS-treated wild-type and Bcl-3^−/− mice, but showed that Bcl-3^−/− mice retained colonic tissue architecture which was absent in wild-type mice following DSS treatment. Analysis of the expression of the proinflammatory cytokines interleukin (IL)-1β, tumour necrosis factor (TNF)-α and IL-6 revealed no significant differences between DSS-treated Bcl-3^−/− and wild-type mice. Analysis of intestinal epithelial cell proliferation revealed enhanced proliferation in Bcl-3^−/− mice, which correlated with preserved tissue architecture. Our results reveal that Bcl-3 has an important role in regulating intestinal epithelial cell proliferation and sensitivity to DSS-induced colitis which is distinct from its role as a negative regulator of inflammation.     

Glomus tympanicum chemodectomas: radiographic and clinical characteristics

Glomus tympanicum chemodectomas are benign neoplasms that develop from normal glomus bodies located along the Jacobson (tympanic) nerve in the middle ear. The medical charts and radiographic studies of 55 patients with these tumors were reviewed. Women outnumbered men in a ratio of 3.5:1, and the patients' average age when they initially reported symptoms was 52 years. Tinnitus, ear pulsations, and diminished hearing were the most frequent symptoms. No patient had a second chemodectoma, and none of seven patients who were tested had elevated neuroendocrine compounds. Review of the radiographic examinations showed that direct coronal, thin-section computed tomography (CT) was the most sensitive means of demonstrating glomus tympanicum chemodectomas. Magnification angiography was also a sensitive diagnostic study, typically depicting a trapezoidal, hypervascular, middle-ear mass that appeared initially in the middle-to-late arterial phase and quickly disappeared in the venous phase. Differentiation from an aberrant internal carotid artery is critical to prevent arterial biopsy.     

Human erythrocyte antigens: II. The In(Lu) gene regulates expression of an antigen on an 80-kilodalton protein of human erythrocytes

We have previously shown that a murine monoclonal antibody (A3D8) identifies a human erythrocyte protein antigen whose expression is regulated by the Lutheran inhibitor [In(Lu)] gene. In the present study, we demonstrated by immunoprecipitation and Western blot techniques that the antigen defined by A3D8 was on an 80-kD erythrocyte membrane protein. A second 170-kD protein was coprecipitated with the 80-kD protein but failed to show antigen activity by Western blot analysis. The 170-kD protein, when analyzed by sodium dodecyl sulfate- polyacrylamide gel electrophoresis in two dimensions, was composed of 50- and 30-kD disulfide-linked subunits. In(Lu) Lu[a-b-) erythrocytes differed from Lu(a+b+) or Lu(a-b+) erythrocytes in that In(Lu) deoxycholate erythrocyte membrane extracts contained trace amounts of immunoprecipitable 80-kD protein compared with detergent-solubilized erythrocyte membrane extracts prepared from Lu(a+b+) or Lu(a-b+) subjects.     

The formation of Ca++-dependent complexes of platelet membrane glycoproteins IIb and IIIa in solution as determined by crossed immunoelectrophoresis

Triton X-100 soluble proteins from 125I-labeled human platelets were studied by crossed immunoelectrophoresis employing a multispecific rabbit antibody raised against whole normal platelets. Emphasis was placed upon an analysis of immunoprecipitates containing 125I-labeled major membrane glycoproteins, and in particular, a prominent immunoprecipitate containing a glycoprotein antigen (s) previously designated as protein 16. SDS-polyacrylamide gel electrophoresis of protein 16 precipitated by a monospecific alloantibody. IgG L . . . , confirmed the presence of both glycoproteins IIb and IIIa. 125I-IgG L . . . , at concentration below that capable of precipitating protein 16 by itself, bound specifically to the precipitate containing protein 16 produced by the multispecific rabbit antibody. No other precipitates formed by the rabbit antibody contained either glycoprotein IIb or IIIa. When platelet proteins, incubated with optimum concentrations of ethylenediamine tetraacetic acid (EDTA) or ethyleneglycol bis (B- aminoethylether) NN1-tetraacetic acid (EGTA), were electrophoresed against the rabbit antibody, previously unobserved immunoprecipitates that contained either free glycoprotein IIb or free glycoprotein IIIa were detected. Upon readdition of excess Ca++, but not Mg++, to the same protein samples, a single immunoprecipitate containing both glycoproteins was once again observed. It is thus demonstrated that glycoproteins IIb and IIIa can form Ca++-dependent complexes (protein 16) in Triton X-100 extracts of normal platelets. The potential significance of the reversible association of these glycoproteins to normal platelet function is discussed.