Acute Posterior Cranial Fossa Hemorrhage-Is Surgical Decompression Better than Expectant Medical Management?

BACKGROUND: To compare the in-hospital mortality and institutional morbidity from medical therapy (MT), external ventricular drainage (EVD) and suboccipital decompressive craniectomy (SDC) following an acute hemorrhagic posterior cranial fossa stroke (PCFH) in patients admitted to the neurosciences critical care unit (NCCU). Retrospective observational single-center cohort study in a tertiary care center. All consecutive patients (n = 104) admitted with PCFH from January 1st 2005-December 31st 2011 were included in the study. METHODS: All patients with a PCFH were identified and confirmed by reviewing computed tomography of the brain reported by a specialist neuroradiologist. Management decisions (MT, EVD, and SDC) were identified from operative notes and electronic patient records. RESULTS: Following a PCFH, 47.8 % (n = 11) patients died after EVD placement without decompression, 45.7 % (n = 16) died following MT alone, and 17.4 % (n = 8) died following SDC. SDC was associated with lower mortality compared to MT with or without EVD (χ 2 test p = 0.006, p = 0.008). Age, ICNARC score, brain stem involvement, and hematoma volume did not differ significantly between the groups. There was a statistically significant increase in hydrocephalus and intraventricular bleeds in patients treated with EVD placement and SDC (χ 2 test p = 0.02). Median admission Glasgow Coma Scale scores for the MT only, MT with EVD, and SDC groups were 8, 6, and 7, respectively (ranges 3-15, 3-11 and 3-13) and did not differ significantly (Friedman test: p = 0.89). SDC resulted in a longer NCCU stay (mean of 17.4 days, standard deviation = 15.4, p < 0.001) and increased incidence of tracheostomy (50 vs. 17.2 %, p = 0.0004) compared to MT with or without EVD. CONCLUSIONS: SDC following PCFH was associated with a reduction in mortality compared to expectant MT with or without EVD insertion. A high-quality multicenter randomized control trial is required to evaluate the superiority of SDC for PCFH.

Poly[d(A.T)] and other synthetic polydeoxynucleotides containing oligoadenosine tracts form nucleosomes easily.

Synthetic double-stranded polydeoxynucleotides of the general form poly[d(AnT).d(ATn)], with n ranging from 3 to 11, have been synthesized. The conformation of the polymers was investigated by circular dichroism spectroscopy and the polymers were examined for their ability to form nucleosomes. Although spectra show that a circular dichroism band characteristic of poly[d(A.T)] appears in the polymer family for n greater than 7, we demonstrate that even polynucleotides with the longest tracts of contiguous adenosine bases (n = 11) are able to form nucleosomes when reconstituted using a histone exchange procedure. Thus resistance to nucleosome formation does not coincide with the appearance of features similar to that of poly[d(A.T)] over the bulk of the nucleosomal DNA. Furthermore, we show that an approximately 150 base-pair poly[d(A.T)] itself, long thought to be refractory to nucleosome formation, can assemble into such a protein-DNA complex when reconstituted by a low-salt exchange procedure. Competitive assays show that the homopolymer reconstitutes about as well as heterogeneous sequences DNA. Our work, therefore, suggests that highly adenosine-rich sequences in vivo apparently have a function that operates at a level other than that of nucleosome structure.

Rapid, non-separation electrochemiluminescent DNA hybridization assays for PCR products, using 3'-labelled oligonucleotide probes.

Described are rapid assays for the analysis of PCR products in a one step, non-separation assay based on the use of electrochemiluminescence generated from a tris-bipyridine ruthenium (II) label. The assay uses PCR incorporation of a biotinylated oligonucleotide as a primer, with the inclusion of a labelled oligonucleotide. Oligonucleotides were labelled with an N-hydroxy succinimide ester of tris-bipyridine ruthenium (II) dihexafluorophosphate (Origen-label) by modifying the 3' and 3' 5' ends of the oligonucleotide probes. The assay makes use of the inherent thermal stability and absence of polymerase activity on such probes to allow the PCR and probe hybridization to be completed automatically on the thermocycler. The assay is concluded by the addition of PCR samples to streptavidin beads on an electrochemiluminescence analyser for binding and analysis. Target genes evaluated were the HIV-1 gag gene, and cystic fibrosis delta F-508 deletion mutation. The results obtained from these assays demonstrated the detection of 10 copies of the HIV-1 gag gene, and cystic fibrosis delta F-508 mutation in 1 ng of human DNA within 15 min. This assay format allows a rapid and simple determination of specific amplified DNA sequences, reducing the contamination risks due to washes and multiple pipetting.

Improved electrochemiluminescent label for DNA probe assays: rapid quantitative assays of HIV-1 polymerase chain reaction products.

We describe the characterization and utility of a new electrochemiluminescent (ECL) label for oligonucleotides, utilizing phosphoramidite chemistry. This phosphoramidite of the tris(2,2-bipyridine)ruthenium(II) complex, bis(2,2-bipyridine)(4-[4-(2-cyanoethoxy-N,N-diisopropyl-amino) phosphinoxybutyl]4'-methyl)2,2-bipyridine ruthenium(II) dihexafluorophosphate or Origen phosphoramidite, enables the direct incorporation of the label during automated DNA synthesis. Efficiency of this automated synthesis allows the direct utilization of probes without further purification. Introduction of this labeling group is reproducible, and the ECL signal recovered is not influenced by hybridization. Furthermore, neither hybridization kinetics nor hybrid stability was affected by our label. We also demonstrate the utility of these labels for the development of rapid assays with oligonucleotides direct from automated synthesis. The clinical utility of these labeled oligonucleotides is shown with assays of total nucleic acid, extracted from peripheral blood lymphocytes of patients with acquired immunodeficiency syndrome (AIDS), to detect the human immunodeficiency virus (HIV-1). The results demonstrate the ability of the assay to quantify 30-2000 copies of HIV1 gag genes and to rapidly detect (less than 45 min) HIV-1 gag genes in a nonseparation assay. The application of this assay to clinical samples demonstrates the utility of these assays for rapid and quantitative analysis.