Remarkably similar antigen receptors among a subset of patients with chronic lymphocytic leukemia

Studies of B cell antigen receptors (BCRs) expressed by leukemic lymphocytes from patients with B cell chronic lymphocytic leukemia (B-CLL) suggest that B lymphocytes with some level of BCR structural restriction become transformed. While analyzing rearranged V(H)DJ(H) and V(L)J(L) genes of 25 non-IgM-producing B-CLL cases, we found five IgG(+) cases that display strikingly similar BCRs (use of the same H- and L-chain V gene segments with unique, shared heavy chain third complementarity-determining region [HCDR3] and light chain third complementarity-determining region [LCDR3] motifs). These H- and L-chain characteristics were not identified in other B-CLL cases or in normal B lymphocytes whose sequences are available in the public databases. Three-dimensional modeling studies suggest that these BCRs could bind the same antigenic epitope. The structural features of the B-CLL BCRs resemble those of mAb's reactive with carbohydrate determinants of bacterial capsules or viral coats and with certain autoantigens. These findings suggest that the B lymphocytes that gave rise to these IgG(+) B-CLL cells were selected for this unique BCR structure. This selection could have occurred because the precursors of the B-CLL cells were chosen for their antigen-binding capabilities by antigen(s) of restricted nature and structure, or because the precursors derived from a B cell subpopulation with limited BCR heterogeneity, or both.     

Formalin-induced infidelity in PCR-amplified DNA fragments

A 643-nucleotide-long fragment of rDNA gene was amplified by PCR in the nematode worm Caenorhabditis. When the experiments were performed by using samples fixed in formalin, artefacts were detected. While the size of the amplified fragment resulted unaffected, very striking differences were seen in the nucleotide sequences of the amplified fragments. Furthermore, in many cases, the PCR reaction failed completely. The results obtained might warn of potential problems, especially when the amount of DNA to be amplified scarce.     

Study protocol: The DOse REsponse Multicentre International collaborative initiative (DO-RE-MI)

Introduction

Current practices for renal replacement therapy in intensive care units (ICUs) remain poorly defined. The DOse REsponse Multicentre International collaborative initiative (DO-RE-MI) will address the issue of how the different modes of renal replacement therapy are currently chosen and performed. Here, we describe the study protocol, which was approved by the Scientific and Steering Committees.

Methods

DO-RE-MI is an observational, multicentre study conducted in ICUs. The primary end-point will be the delivered dose of dialysis, which will be compared with ICU mortality, 28-day mortality, hospital mortality, ICU length of stay and number of days of mechanical ventilation. The secondary end-point will be the haemodynamic response to renal replacement therapy, expressed as percentage reduction in noradrenaline (norepinephrine) requirement. Based on the the sample analysis calculation, at least 162 patients must be recruited. Anonymized patient data will be entered online in electronic case report forms and uploaded to an internet website. Each participating centre will have 2 months to become acquainted with the electronic case report forms. After this period official recruitment will begin. Patient data belong to the respective centre, which may use the database for its own needs. However, all centres have agreed to participate in a joint effort to achieve the sample size needed for statistical analysis.

Conclusion

The study will hopefully help to collect useful information on the current practice of renal replacement therapy in ICUs. It will also provide a centre-based collection of data that will be useful for monitoring all aspects of extracorporeal support, such as incidence, frequency, and duration.     

The Ubiquitin–Proteasome System Regulates the Stability of Neuronal Nicotinic Acetylcholine Receptors

Ubiquitination is a key event for protein degradation by the proteasome system, membrane protein internalization, and protein trafficking among cellular compartments. Few data are available on the role of the ubiquitin–proteasome system (UPS) in the trafficking of neuronal nicotinic acetylcholine receptors (nAChRs). Experiments conducted in neuron-like differentiated rat pheochromocytoma cells (PC12 cells) show that the α3, β2, and β4 nAChR subunits are ubiquitinated and that their ubiquitination is necessary for degradation. A 24-h treatment with the proteasome inhibitor PS-341 increased the total levels of α3 and the two β subunits in both whole cell lysates and fractions enriched for the ER/Golgi compartment. nAChR subunit upregulation was also detected in plasma membrane-enriched fractions. Inhibition of the lysosomal degradation machinery by E-64 had a significantly smaller effect on nAChR turnover. The present data, together with previous results showing that the α7 nAChR subunit is a target of the UPS, point to a prominent role of the proteasome in nAChR trafficking.     

A comparison between the early and mid-term results of surgical as opposed to percutaneous closure of defects in the oval fossa in children aged less than 6 years

OBJECTIVES: To compare surgical as opposed to percutaneous interventional closure of isolated atrial septal defects in the oval fossa in terms of hospital stay, efficacy, and complications, and to study the respective role of the two techniques in current practice. METHODS: Between January 1998 and April 2004, 126 out of 1210 patients treated at our institution for closure of an isolated defect in the oval fossa were aged less than 6 years. The mean age of these 126 patients at procedure was 4.2 plus or minus 1 year. The ratio of females to males was 74 to 52. RESULTS: Of the patients, 62% were treated successfully using a percutaneous approach. The groups treated surgically or percutaneously did not differ for age, gender, or indications for treatment. No deaths occurred. The rates of total and major complications were higher in the group undergoing surgical closure, at 34% versus 9%, p less than 0.0001, and 10.5% versus 1%, p equal to 0.01, respectively. Embolisation of the device requiring subsequent surgery occurred in 1% of patients. The stay in hospital was shorter in those closed percutaneously, at 3.2 plus or minus 0.9 days versus 6.8 plus or minus 2.8 days, p equal to 0.0001. During a mean follow-up of 3.4 plus or minus 1.9 years, no major complications occurred in either group, and symptoms improved significantly in both groups. Additional sequels occurred in 2 patients who had major complications subsequent to surgical closure. CONCLUSIONS: Even in young children, it is both feasible and safe to close defects in the oval fossa percutaneously. Compared to surgical closure, the transcatheter approach allows a shorter stay in hospital, and has a lower rate of complications. Early and mid-term follow-up has confirmed the safety and efficacy of both techniques.     

PIN-1 promoter polymorphisms in mild cognitive impairment and susceptibility to Alzheimer's disease: a preliminary report

BACKGROUND AND AIMS: Peptydil prolyl cis-trans isomerase (PIN-1), which specifically regulates the conformational changes following phosphorylation of several proteins, targets the inactive hyper-phosphorylated tau on the Thr231-Pro motif and directly restores its biological function. Interestingly, PIN-1 is oxidatively inhibited not only in Alzheimer's disease brain but also in the hippocampi of mild cognitive impairment (MCI) subjects. The PIN-1 gene is characterized by two single nucleotide polymorphisms (SNPs) in the promoter region which are associated with the risk of Alzheimer's disease. The aim of this study was to analyse the genotype and allele distributions of these PIN-1 SNPs in MCI subjects diagnosed respectively as amnestic MCI (a-MCI) and multiple impaired cognitive domains (mcd-MCI) on the basis of cognitive features. METHODS: -667 T/C and -842 C/G SNPs were genotyped by polymerase chain reaction (PCR) amplification and direct sequencing in 43 MCI subjects, with the intention of comparing -667 and -842 SNP frequencies with those previously described in 111 Alzheimer's disease patients (AD) and 73 healthy controls (HC). RESULTS: The allele frequencies of the -842 C/G SNP in a-MCI subjects are similar to those of AD subjects, while those of mcd-MCI are comparable to HC (G allele 83% in both a-MCI and AD; 95% and 94% in mcd-MCI and HC, respectively). A similar trend is also observed in -842 C/G genotypes. CONCLUSIONS: Since a-MCI is thought to be the preclinical form of AD, the similar genotype distribution of -842 SNP in AD and a-MCI, but not in mcd-MCI, suggests that it is potentially involved in the conversion of a-MCI to AD. In conclusion, these findings support the theory that polymorphisms of the PIN-1 gene can affect neurodegeneration and its clinical progression.