Expression of Kir4.1 and Kir5.1 inwardly rectifying potassium channels in oligodendrocytes, the myelinating cells of the CNS

The inwardly rectifying K+ channel subtype Kir5.1 is only functional as a heteromeric channel with Kir4.1. In the CNS, Kir4.1 is localised to astrocytes and is the molecular basis of their strongly negative membrane potential. Oligodendrocytes are the specialised myelinating glia of the CNS and their resting membrane potential provides the driving force for ion and water transport that is essential for myelination. However, little is known about the ion channel profile of mature myelinating oligodendrocytes. Here, we identify for the first time colocalization of Kir5.1 with Kir4.1 in oligodendrocytes in white matter. Immunolocalization with membrane-bound Na+/K+-ATPase and western blot of the plasma membrane fraction of the optic nerve, a typical CNS white matter tract containing axons and the oligodendrocytes that myelinate them, demonstrates that Kir4.1 and Kir5.1 are colocalized on oligodendrocyte cell membranes. Co-immunoprecipitation provides evidence that oligodendrocytes and astrocytes express a combination of homomeric Kir4.1 and heteromeric Kir4.1/Kir5.1 channels. Genetic knock-out and shRNA to ablate Kir4.1 indicates plasmalemmal expression of Kir5.1 in glia is largely dependent on Kir4.1 and the plasmalemmal anchoring protein PSD-95. The results demonstrate that, in addition to astrocytes, oligodendrocytes express both homomeric Kir4.1 and heteromeric Kir4.1/Kir5.1 channels. In astrocytes, these channels are essential to their key functions of K+ uptake and CO2/H+ chemosensation. We propose Kir4.1/Kir5.1 channels have equivalent functions in oligodendrocytes, maintaining myelin integrity in the face of large ionic shifts associated with action potential propagation along myelinated axons.

Results of a phase I/II clinical trial of BPX-101, a novel drug-activated dendritic cell (DC) vaccine for metastatic castration-resistant prostate cancer (mCRPC)

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Background: We report results of a phase I/II clinical trial of BPX-101, a drug- activated autologous DC vaccine targeting PSMA.

Methods: Men with progressive mCRPC following up to one prior chemotherapy regimen were enrolled in a 3+3 dose escalation trial evaluating BPX-101 and CD40 activating agent AP1903. BPX-101 was administered intradermally every 2 weeks for 6 doses, during the induction phase, and for nonprogressing patients, every 8 weeks for up to 5 doses during the maintenance phase. AP1903 (0.4 mg/kg) was infused 24 hours after each BPX-101 dose. Radiologic evaluation was performed every 12 weeks.

Results: Planned enrollment of 12 subjects has been completed, including 3 each at 4 × 106 and 12.5 × 106 cells/dose, and 6 at 25 × 106 cells/dose. All vaccine products were releasable. Median Halabi- predicted survival was 13.8 months. Two subjects went off protocol prior to the end of induction due to progression, 8 reached end of induction, and 2 are nearing completion of induction. Toxicities (e.g. injection site reactions) were generally mild. One high dose subject experienced a single acute cytokine reaction during infusion of AP1903 at the second vaccination, but continued induction without further drug-related adverse events. Notably, one post- docetaxel subject in the low dose cohort achieved a RECIST PR, and one chemo-naive subject in the mid-dose cohort with extensive visceral, nodal, and bone metastases experienced a RECIST CR with docetaxel-based chemotherapy after induction and maintains an undetectable ultrasensitive PSA (0.009 ng/mL) 10 months after enrollment. A third subject, in the high-dose cohort, experienced near complete elimination of multiple lung metastases with otherwise stable disease by the end of induction. Robust immune responses were seen in all three.

Conclusions: BPX-101 can be reliably manufactured and safely administered, followed by AP1903, at doses of at least 25 × 106 cells. Contrary to the observation that cancer vaccine therapy improves survival without short-term response, BPX-101-treated patients have experienced measurable disease responses, including near elimination of poor-risk visceral disease.

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Colloid solutions for fluid resuscitation

BACKGROUND

Colloids are widely used in the replacement of fluid volume. However doubts remain as to which colloid is best. Different colloids vary in their molecular weight and therefore in the length of time they remain in the circulatory system. Because of this and their other characteristics, they may differ in their safety and efficacy.

OBJECTIVES

To compare the effects of different colloid solutions in patients thought to need volume replacement.

SEARCH STRATEGY

We searched the Cochrane Injuries Group specialised register, the Cochrane Controlled Trials Register (2002 Issue 3), MEDLINE (1994-2002/07), EMBASE (1974-2002 August week 1), and the National Research Register (2002 issue 3). Bibliographies of trials retrieved were searched, and drug companies manufacturing colloids were contacted for information. The search was last updated in September 2002.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing colloid solutions in critically ill and surgical patients thought to need volume replacement. The main outcomes measured were death, amount of whole blood transfused, and incidence of adverse reactions.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data and assessed the quality of the trials.

MAIN RESULTS

Fifty-seven trials met the inclusion criteria, with a total of 3659 participants. Quality of allocation concealment was judged to be adequate in 20 trials and poor or uncertain in 37. Deaths were obtained from 36 trials. For albumin or PPF versus hydroxyethyl starch (HES) 20 trials (n=1029) reported mortality. The pooled relative risk (RR) was 1.17 (95% CI 0.91, 1.50). For albumin or PPF versus gelatin four trials (n=542) reported mortality. The RR was 0.99 (0.69, 1.42). For gelatin vs HES 11 trials (n=945) reported mortality, RR was 1.00 (0.78,1.28). RR was not estimable in the albumin vs dextran, gelatin vs dextran, and HES vs dextran groups. Thirty-six trials recorded the amount of blood transfused, however quantitative analysis was not possible due to skewness and variable reporting. Fifteen trials recorded adverse reactions, but none occurred.

REVIEWER'S CONCLUSIONS

From this review, there is no evidence that one colloid solution is more effective or safe than any other, although the confidence intervals are wide and do not exclude clinically significant differences between colloids. Larger trials of fluid therapy are needed if clinically significant differences in mortality are to be detected or excluded.

The prostate expression database (PEDB): status and enhancements in 2000

The Prostate Expression Database (PEDB) is an online resource designed to access and analyze gene expression information derived from the human prostate. PEDB archives >55 000 expressed sequence tags (ESTs) from 43 cDNA libraries in a curated relational database that provides detailed library information including tissue source, library construction methods, sequence diversity and sequence abundance. The differential expression of each EST species can be viewed across all libraries using a Virtual Expression Analysis Tool (VEAT), a graphical user interface written in Java for intra- and inter-library species comparisons. Recent enhancements to PEDB include: (i) the functional categorization of annotated EST assemblies using a classification scheme developed at The Institute for Genome Research; (ii) catalogs of expressed genes in specific prostate tissue sources designated as transcriptomes; and (iii) the addition of prostate proteome information derived from two-dimensional electrophoreses and mass spectrometry of prostate cancer cell lines. PEDB may be accessed via the WWW at http://www.mbt.washington.edu/PEDB/

Negative selection: a method for obtaining low-abundance cDNAs using high-density cDNA clone arrays

The identification of the entire complement of genes expressed in a cell, tissue, or organism provides a framework for understanding biological properties and establishes a tool set for subsequent functional studies. The large-scale sequencing of randomly selected clones from cDNA libraries has been successfully employed as a method for identifying a large fraction of these expressed genes. However, this approach is limited by the inherent redundancy of cellular transcripts reflecting widely variant levels of gene transcription. As a result, a high percentage of transcript duplications are encountered as the number of sequenced clones accrues. To address this problem, we have developed a negative hybridization selection method that employs the hybridization of complex cDNA probes to high-density arrays of cDNA clones and the subsequent selection of clones with a null or low hybridization signal. This approach was applied to a cDNA library constructed from normal human prostate tissue and resulted in the reduction of highly expressed prostate cDNAs from 6.8 to 0.57% with an overall decline in clone redundancy from 33 to 11%. The selected clones also reflected a more diverse cDNA population, with 89% of the clones representing distinctly different cDNAs compared with 67% of the randomly selected clones. This method compares favorably with cDNA library re-association normalization approaches and offers several distinct advantages, including the flexibility to use previously prepared libraries, and the ability to employ an iterative screening approach for continued accrual of cDNAs representing rare transcripts.

Kynostatin and 17beta-estradiol prevent the apoptotic death of human neuroblastoma cells exposed to HIV-1 protease

A significant number of adult male patients with acquired immunodeficiency syndrome develop cerebral atrophy and progressive brain disorders such as dementia complex and neuropsychiatric problems. Upon entering the brain via activated macrophages or microglias, the human immunodeficiency type 1 virus (HIV-1) may produce cytotoxic factors such as HIV-1 envelope protein (gp120) and protease. Owing to significant proteolysis of nonviral proteins, the protease derived from HIV-1 may be detrimental to brain cells and neurons. Our results revealed that HIV-1 protease, at nanomolar concentrations, was as potent as gp120 in causing neurotoxicity in human neuroblastoma neurotypic SH-SY5Y cells. As shown by the Oncor ApopTag staining procedure, HIV-1 protease significantly increased the number of apoptotic cells over the serum-free controls. Moreover, HIV-1 protease-induced neurotoxicity was blocked by a selective protease inhibitor, kynostatin (KNI-272). Antioxidants such as 17beta-estradiol, melatonin, and S-nitrosoglutathione also prevented protease-induced neurotoxicity. These findings indicate that oxidative proteolysis may mediate HIV-1 protease-induced apoptosis and the degeneration of neurons and other brain cells. Centrally active protease inhibitors and antioxidants may play an important role in preventing cerebral atrophy and associated dementia complex caused by HIV-1.

PEDB: the Prostate Expression Database

The Prostate Expression Database (PEDB) is a curated relational database and suite of analysis tools designed for the study of prostate gene expression in normal and disease states. Expressed Sequence Tags (ESTs) and full-length cDNA sequences derived from more than 40 human prostate cDNA libraries are maintained and represent a wide spectrum of normal and pathological conditions. Detailed library information including tissue source, library construction methods, sequence diversity and abundance are available in a library archive. Prostate ESTs are assembled into distinct species groups using the multiple alignment program CAP2 and are annotated with information from the GenBank, dbEST and Unigene public sequence databases. Annotated sequences in PEDB are searched using the BLAST algorithm. The differential expression of each EST species can be viewed across all libraries using a Virtual Expression Analysis Tool (VEAT), a graphical user interface written in Java for intra- and inter-library species comparisons. PEDB may be accessed via the World Wide Web at http://www.mbt.washington.edu/PEDB/

Hyperplastic Refractory Anemia

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