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PubMed1999

DNA demethylase is a processive enzyme.

DNA methylation patterns are generated during development by a sequence of methylation and demethylation events. We have recently demonstrated that mammals bear a bona fide demethylase enzyme that removes methyl groups from methylated cytosines. A general genome wide demethylation occurs early in development and in differentiating cell lines. This manuscript tests the hypothesis that the demethylase enzyme is a processive enzyme. Using bisulfite mapping, this report demonstrates that demethylase is a processive enzyme and that the rate-limiting step in demethylation is the initiation of demethylation. Initiation of demethylation is determined by the properties of the sequence. Once initiated, demethylation progresses processively. We suggest that these data provide a molecular explanation for global hypomethylation.

CpG Islands↗
PubMed1985

Cytoskeletal architecture and immunocytochemical localization of microtubule-associated proteins in regions of axons associated with rapid axonal transport: the beta,beta'-iminodipropionitrile-intoxicated axon as a model system.

Axons from rats treated with the neurotoxic agent beta,beta'-iminodipropionitrile (IDPN) were examined by quick-freeze, deep-etch electron microscopy. Microtubules formed bundles in the central region of the axons, whereas neurofilaments were segregated to the periphery. Most membrane-bounded organelles, presumably including those involved in rapid axonal transport, were associated with the microtubule domain. The high resolution provided by quick-freeze, deep-etch electron microscopy revealed that the microtubules were coated with an extensive network of fine strands that served both to cross-link the microtubules and to interconnect them with the membrane-bounded organelles. The strands were decorated with granular materials and were irregular in dimension. They appeared either singly or as an extensive anastomosing network in fresh axons. The microtubule-associated strands were observed in fresh, saponin-extracted, or aldehyde-fixed tissue. To explore further the identity of the microtubule-associated strands, microtubules purified from brain tissue and containing the high molecular weight microtubule-associated proteins MAP 1 and MAP 2 were examined by quick-freeze, deep-etch electron microscopy. The purified microtubules were connected by a network of strands quite similar in appearance to those observed in the IDPN axons. Control microtubule preparations consisting only of tubulin and lacking the MAPs were devoid of associated strands. To learn which of the MAPs were present in the microtubule bundles in the axon, sections of axons from IDPN-treated rats were examined by immunofluorescence microscopy using antibodies to MAP 1A, MAP 1B, MAP 2, and tubulin. Anti-MAP 2 staining was only marginally detectable in the IDPN-treated axons, consistent with earlier observations. Anti-MAP 1A and anti-MAP 1B brightly stained the IDPN-treated axons, with the staining exclusively limited to the microtubule domains. Furthermore, thin section-immunoelectron microscopy using colloidal gold-labeled second antibodies revealed that both anti-MAP 1A and anti-MAP 1B stained fuzzy filamentous structures between microtubules. In view of earlier work indicating that rapid transport is associated with the microtubule domain in the IDPN-treated axon, it now appears that MAP 1A and MAP 1B may play a role in this process. We believe that MAP 1A and MAP 1B are major components of the microtubule-associated fibrillar matrix in the axon.

Animals↗
PubMed2001

The use of node-link mapping in the chemical dependency treatment of adolescents.

The current study examined treatment perceptions of youth adjudicated to an eight-month residential treatment facility. Participants were randomly assigned to standard or mapping-enhanced counseling. They completed established questionnaires assessing group sessions, program features, treatment motivation, and number of program infractions. Mapping residents rated group sessions as deeper over time. Mapped sessions appeared to also maintain residents' arousal over time. Mapping residents rated themselves as more motivated to get along with staff, and also tended to be more motivated to engage in the treatment process. In addition, mapping residents had fewer program infractions thirty days after the beginning of the experiment compared to standard residents. These findings extend previous research on node-link mapping in adult treatment settings.

Adolescent↗
PubMed2004

Gradient-based multiresolution image fusion.

A novel approach to multiresolution signal-level image fusion is presented for accurately transferring visual information from any number of input image signals, into a single fused image without loss of information or the introduction of distortion. The proposed system uses a "fuse-then-decompose" technique realized through a novel, fusion/decomposition system architecture. In particular, information fusion is performed on a multiresolution gradient map representation domain of image signal information. At each resolution, input images are represented as gradient maps and combined to produce new, fused gradient maps. Fused gradient map signals are processed, using gradient filters derived from high-pass quadrature mirror filters to yield a fused multiresolution pyramid representation. The fused output image is obtained by applying, on the fused pyramid, a reconstruction process that is analogous to that of conventional discrete wavelet transform. This new gradient fusion significantly reduces the amount of distortion artefacts and the loss of contrast information usually observed in fused images obtained from conventional multiresolution fusion schemes. This is because fusion in the gradient map domain significantly improves the reliability of the feature selection and information fusion processes. Fusion performance is evaluated through informal visual inspection and subjective psychometric preference tests, as well as objective fusion performance measurements. Results clearly demonstrate the superiority of this new approach when compared to conventional fusion systems.

Algorithms↗
PubMed1991

Processing of the precursor of protamine P2 in mouse. Peptide mapping and N-terminal sequence analysis of intermediates.

Protamine P2, the major basic chromosomal protein of mouse spermatozoa, is synthesized as a precursor almost twice as long as the mature protein, its extra length arising from an N-terminal extension of 44 amino acid residues. This precursor is integrated into chromatin of spermatids, and the extension is processed during chromatin condensation in the haploid cells. We have studied processing in the mouse and have identified two intermediates generated by proteolytic cleavage of the precursor. H.p.l.c. separated protamine P2 from four other spermatid proteins, including the precursor and three proteins known to possess physiological characteristics expected of processing intermediates. Peptide mapping indicated that all of these proteins were structurally similar. Two major proteins were further purified by PAGE, transferred to poly(vinylidene difluoride) membranes and submitted to automated N-terminal sequence analysis. Both sequences were found within the deduced sequence of the precursor extension. The N-terminus of the larger intermediate, PP2C, was Gly-12, whereas the N-terminus of the smaller, PP2D, was His-21. Both processing sites involved a peptide bond in which the carbonyl function was contributed by an acidic amino acid.

Amino Acid Sequence↗
PubMed2000

Multisensory auditory-somatosensory interactions in early cortical processing revealed by high-density electrical mapping.

We investigated the time-course and scalp topography of multisensory interactions between simultaneous auditory and somatosensory stimulation in humans. Event-related potentials (ERPs) were recorded from 64 scalp electrodes while subjects were presented with auditory-alone stimulation (1000-Hz tones), somatosensory-alone stimulation (median nerve electrical pulses), and simultaneous auditory-somatosensory (AS) combined stimulation. Interaction effects were assessed by comparing the responses to combined stimulation with the algebraic sum of responses to the constituent auditory and somatosensory stimuli when they were presented alone. Spatiotemporal analysis of ERPs and scalp current density (SCD) topographies revealed AS interaction over the central/postcentral scalp which onset at approximately 50 ms post-stimulus presentation. Both the topography and timing of these interactions are consistent with multisensory integration early in the cortical processing hierarchy, in brain regions traditionally held to be unisensory.

Acoustic Stimulation↗
PubMed1981

Regional pattern of degeneration in Alzheimer's disease: neuronal loss and histopathological grading.

The various structural components of the cortical degeneration of Alzheimer's disease were defined and graded. The severity of the degenerative process was thus mapped in different cortical areas where neuronal numbers and cortical width were also measured and compared with controls. Contrary to the general opinion that the degenerative process is rather uniformly diffuse, though accentuated in the medial temporal and frontal cortex, we found a consistent and more elaborate pattern with clearcut regional differences. Thus the degeneration involved, besides basal medial temporal limbic areas, the posterior cingulate gyrus and superior parietal lobule particularly, with somewhat less marked changes in the inferior parietal lobule and inferior temporal gyri. The sensorimotor, calcarine and anterior cingulate areas of the cortex were notably spared until very late stages. This regionally variable severity of the degeneration was also paralleled by a regionally varying reduction in neuronal numbers and cortical width, and agrees with our previously published results of a regional pattern which closely correlates with clinical parameters, including symptom pattern and regional cerebral blood flow alterations.

Aged↗
PubMed1981

The nucleotide sequence of the intergenic region between the 5.8S and 26S rRNA genes of the yeast ribosomal RNA operon. Possible implications for the interaction between 5.8S and 26S rRNA and the processing of the primary transcript.

We have determined the nucleotide sequence of part of a cloned yeast ribosomal RNA operon extending from the 5.8S RNA gene downstream into the 5' -terminal region of the 26S RNA gene. We mapped the pertinent processing sites, viz. the 5' end of 26S rRNA and the 3'ends of 5.8S rRNA and its immediate precursor, 7S RNA. At the 3' end of 7S RNA we find the sequence UCGUUU which is very similar to the type I consensus sequence UCAUUA/U present at the 3' ends of 17S, 5.8S and 26S rRNA as well as 18S precursor rRNA in yeast. At the 5' end of the 26S RNA gene we find a sequence of thirteen nucleotides which is homologous to the type II sequence present at the 5' termini of both the 17S and the 5.8S RNA gene. These findings further support the suggestion put forward earlier (G.M. Veldman et al. (1980) Nucl. Acids Res. 8, 2907-2920) that both consensus sequences are involved in the recognition of precursor rRNA by the processing nuclease(s). We discuss a model for the processing of yeast rRNA in which a processing enzyme sequentially recognizes several combinations of a type I and a type II consensus sequence. We also describe the existence of a significant base complementarity between sequences in the 5' -terminal region of 26S rRNA and the 3' -terminal region of 5.8S rRNA. We suggest that base pairing between these sequences contributes to the binding between 5.8S and 26S rRNA.

Base Sequence↗
PubMed2004

Concurrent tonotopic processing streams in auditory cortex.

The basis for multiple representations of equivalent frequency ranges in auditory cortex was studied with physiological and anatomical methods. Our goal was to trace the convergence of thalamic, commissural, and corticocortical information upon two tonotopic fields in the cat, the primary auditory cortex (AI) and the anterior auditory field (AAF). Both fields are among the first cortical levels of processing. After neurophysiological mapping of characteristic frequency, we injected different retrograde tracers at separate, frequency-matched loci in AI and AAF. We found differences in their projections that support the notion of largely segregated parallel processing streams in the auditory thalamus and cerebral cortex. In each field, ipsilateral cortical input amounts to approximately 70% of the number of cells projecting to an isofrequency domain, while commissural and thalamic sources are each approximately 15%. Labeled thalamic and cortical neurons were concentrated in tonotopically predicted regions and in smaller loci far from their spectrally predicted positions. The few double-labeled thalamic neurons (<2%) are consistent with the hypothesis that information to AI and AAF travels along independent processing streams despite widespread regional overlap of thalamic input sources. Double labeling is also sparse in both the corticocortical and commissural systems ( approximately 1%), confirming their independence. The segregation of frequency-specific channels within thalamic and cortical systems is consistent with a model of parallel processing in auditory cortex. The global convergence of cells outside the targeted frequency domain in AI and AAF could contribute to context-dependent processing and to intracortical plasticity and reorganization.

Acoustic Stimulation↗
PubMed1996

3' Processing and termination of mouse histone transcripts synthesized in vitro by RNA polymerase II.

The highly expressed mouse histone H2a-614 gene is located 800 nt 5' of the histone H3-614 gene. There is a 140 nt sequence located 500 nt from the end of the H2-614 mRNA which has been defined as a transcription termination site for RNA polymerase II. We established an in vitro transcription system in which both 3' end processing and transcription termination occur. A template containing the adenovirus major late promoter, a portion of the histone H2a-614 coding region, its 3' processing signal, followed by the transcription termination site was transcribed in a nuclear extract prepared from mouse myeloma cells. Some of the transcripts synthesized in the extract were cleaved at the histone processing site in a reaction which was dependent both on the hairpin binding factor and the U7 snRNP. The efficiency of histone 3' end formation was similar both on synthetic transcripts and transcripts synthesized by RNA polymerase II. Defined transcripts, which were not processed and which mapped to the transcription termination site, were released from the template, suggesting that they were formed by transcription termination. Termination in vitro was dependent on a functional histone processing signal.

Animals↗
PubMed2001

Brain mapping of bilateral visual interactions in children.

Interhemispheric interactions were studied with functional brain mapping of visual processing. Children performed a reaction time task with uni- and bilateral targets and nontargets. The visual evoked potential (VEP) was segmented into P1a, P1b, and N1 microstates using map rather than channel features. Map latencies, amplitudes and sources were tested for bilateral interactions. Bilateral targets yielded shorter VEP map latencies but later response onsets than unilateral ones. Source analyses of the unilateral VEPs indicated a transition from contra- (P1a) to ipsilateral (P1b) visual cortex activation (interhemispheric transfer). Bilateral VEPs were smaller than the summed unilateral VEPs in all microstates. indicating that interhemispheric interactions both precede and follow interhemispheric transfer. Brain mapping of uni- and bilateral VEPs in children thus revealed several distinct forms of interhemispheric interactions in the same, early time range.

Brain Mapping↗
PubMed1989

Identification in maize mitochondrial 26S rRNA of a short 5'-end sequence possibly involved in transcription initiation and processing.

By direct RNA mapping, we have identified the precise 5' end of the maize mitochondrial 26S rRNA. The 5' termini of the 26S rRNA are 17 and 18 nt downstream from the 5' end predicted by Dale et al. (1984) from homology between the maize rRNA and E. coli large subunit ribosomal RNA. In addition, we have discovered a larger 26S species, presumably a 26S precursor, and precisely mapped its 5' end. The maize mitochondrial rRNA genes are probably regulated by control regions that differ from those already characterized in other genomes: the maize mitochondrial 26S, 18S and 5S rRNAs lack sequences that resemble the promoter regions of genes from other mitochondria and bacteria. However, the mature and precursor rRNAs all contain a tetranucleotide, AAUC, at their 5' ends (AAAC in the 5S rRNA). The sequence is also seen in the same position in several other plant mitochondrial mRNAs. We propose therefore that AAUC is a transcription or processing signal which is possibly unique to plant mitochondria.

Base Sequence↗
PubMed2003

Recognizing the institutional benefits of bar-code point-of-care technology.

BACKGROUND: The application of bar-code technology to medication administration is growing, and its benefits are increasingly recognized. This article describes a hospital's experience with bar-code point-of-care (BPOC) technology and discusses the benefits of BPOC, considers the essential role of the pharmacist when implementing BPOC in a hospital setting, and provides a financial model for cost avoidance using a BPOC system. IMPLEMENTING BPOC: In 1998 Northern Michigan Regional Health System (Petoskey, Mich) partnered with a software company to create a BPOC system. Major milestones associated with implementation were involving and preparing end users, examining the hospital's entire medication process, updating the formulary and mapping drugs accurately, and identifying a process to maximize bar-code label attachment to medications. RESULTS: Visibility of prevented errors increased as compared with occurrence reports. Among the prevented errors, approximately 25% of the not-due errors occurred between shifts or between caregivers; wrong-dose errors included nurse attempts to give one tablet when two were ordered and giving two tablets when one was ordered; and wrong-patient errors were predominantly associated with intravenous piggyback medications. Omitted doses or missed doses were virtually eliminated by BPOC. DISCUSSION: A BPOC system provides a much-needed safety net at the bedside to avert potentially injurious medication errors. Another benefit that a BPOC system provides is a record of actual medication administrations. Conducting a thorough assessment of a hospital's readiness for a BPOC system will guide system implementation and help avoid potential installation pitfalls.

Clinical Pharmacy Information Systems↗
PubMed2006

Modified culture protocol for isolation of Mycobacterium avium subsp. paratuberculosis from raw milk.

A modified culture method using C18-carboxypropylbetaine (CB-18) and microscopic screening was evaluated for time to and limit of detection of Mycobacterium avium subsp. paratuberculosis (MAP) in raw milk. Bulk-tank milk samples were spiked with six different concentrations (10(1) to 10(6) CFU/mL) of MAP. Samples were processed using two different protocols. The first protocol involved specimen processing with the zwitterionic detergent C18-carboxypropylbetaine (CB-18) and lytic enzymes followed by culture on modified Middlebrook 7H10 agar plates with microscopic screening. The second protocol used 0.75% hexadecylpyridinium chloride (HPC) for specimen processing, followed by culture on Herrold's egg yolk medium (HEYM). Both protocols were repeated eight independent times, and the detection limit and time to detection were compared. The presence of MAP in spiked milk samples was detected between 14 and 45 days (N [number of samples], 46; mean, 22.7; median, 19.5) using the CB-18 and microscopic screening method, and between 21 and 63 days (N, 47; mean, 31; median, 28) using HEYM (P < 0.001). Time to detection also varied with MAP concentration (P < 0.001). Higher concentrations of MAP were detected earlier than lower concentrations and this finding was independent of the method used (P = 0.479). The two methods had similar detection limits but the modified culture method reduced the time to detect MAP in raw milk for the majority of concentrations.

Animals↗
PubMed2001

First-passage-time exponent for higher-order random walks: using Lévy flights.

We present a heuristic derivation of the first-passage-time exponent for the integral of a random walk [Y. G. Sinai, Theor. Math. Phys. 90, 219 (1992)]. Building on this derivation, we construct an estimation scheme to understand the first-passage-time exponent for the integral of the integral of a random walk, which is numerically observed to be 0.220+/-0.001. We discuss the implications of this estimation scheme for the nth integral of a random walk. For completeness, we also address the n=infinity case. Finally, we explore an application of these processes to an extended, elastic object being pulled through a random potential by a uniform applied force. In so doing, we demonstrate a time reparametrization freedom in the Langevin equation that maps nonlinear stochastic processes into linear ones.

Journal Article↗
PubMed1989

Members of the human glyceraldehyde-3-phosphate dehydrogenase-related gene family map to dispersed chromosomal locations.

Several highly homologous glyceraldehyde-3-phosphate dehydrogenase (GAPD)-related sequences have been identified previously in human DNA by Southern blot analysis. Protein studies have identified only a single expressed locus for this major glycolytic enzyme, and this maps to chromosome 12p13. Sequence analysis of a GAPD muscle cDNA clone and a GAPD-related clone retrieved from an X-chromosome recombinant library showed that the latter was a processed pseudogene that maps to Xp11-p21. In this study, we have determined the chromosomal locations of several of the additional GAPD-related human sequences using a short 3' end sequence from the cDNA to probe DNA from a series of human-rodent somatic cell hybrids on Southern blots. Eight HindIII GAPD-related sequences detected at high stringency have been mapped to 6 different chromosomes. Several of the additional sequences detected at more moderate stringency have been localized to a further 10 chromosomal sites. Together, these sites constitute the known expressed locus, the known X-linked pseudogene, and 15 GAPD-like loci.

Animals↗
PubMed1995

Ketamine does not increase cerebral blood flow velocity or intracranial pressure during isoflurane/nitrous oxide anesthesia in patients undergoing craniotomy.

Ketamine's effect on cerebral hemodynamics is controversial. We hypothesized that ketamine would not increase intracranial pressure (ICP) and cerebral blood flow (CBF) velocity in anesthetized, ventilated patients. Twenty patients requiring craniotomy for brain tumor or cerebral aneurysm were studied. After induction with thiopental, anesthesia was maintained with isoflurane and nitrous oxide in oxygen. During controlled ventilation (PaCO2 34 +/- 1 mm Hg); middle cerebral artery blood flow velocity (VMCA), mean arterial blood pressure (MAP), bilateral frontooccipital processed electroencephalogram (EEG), and ICP were measured before and for 10 min after intravenous ketamine 1.0 mg/kg. Cerebral arteriovenous oxygen content difference (AVDO2) and cerebral perfusion pressure (CPP) were calculated. After ketamine, MAP, CPP, PaCO2, and AVDO2 were unchanged. ICP decreased from 16 +/- 1 mm Hg to 14 +/- 1 mm Hg (mean +/- SE; P < 0.001) and VMCA decreased from 44 +/- 4 cm/s to 39 +/- 4 cm/s (P < 0.001). Total EEG power decreased (P < 0.02). These results suggest that ketamine can be used in anesthetized, mechanically ventilated patients with mildly increased ICP without adversely altering cerebral hemodynamics.

Anesthesia, Inhalation↗