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D B Rowe

Publications and source records attributed to D B Rowe.

9 recordsLinked to original sources
PubMed2001

Bayesian source separation for reference function determination in fMRI.

In analyzing fMRI results, identification of significant activation in voxels is a crucial task. A standard method selects a "known" reference function and performs a regression of the time courses on it and a linear trend. Once the linear trend is found, the correlation between the assumed to be known reference function and the detrended observed time-course in each voxel is computed. But the most important question is: How does one choose the reference function? Here, a Bayesian source separation approach to determining the underlying reference function is described and applied to real fMRI data. This underlying reference function is the unobserved response due to the presentation of the experimental stimulus.

Bayes Theorem↗
PubMed2000

Effect of granulocyte-macrophage colony-stimulating factor deficiency on ovarian follicular cell function.

Granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine secreted by lymphohaemopoietic and other cell lineages, is known to influence ovarian cyclicity and embryo development. The aim of this study was to examine the effect of GM-CSF on ovarian follicular cell function using GM-CSF-deficient (GM -/-) mice. Immature GM -/- and GM +/+ mice were stimulated with eCG, and cumulus-oocyte complexes and mural granulosa cells were collected 48 h later. Expression of GM-CSF receptor (GM-CSFR) alpha and beta mRNA subunits by cumulus-oocyte complexes and mural granulosa cells was examined using RT-PCR. Cumulus-oocyte complexes from both genotypes were found to express mRNA for the GM-CSFRalpha-subunit only, while the mural granulosa cells expressed both the alpha and beta receptor subunits. Cumulus-oocyte complexes recovered from GM -/- mice had approximately twice the number of cumulus cells per cumulus-oocyte complex than did those of GM +/+ mice (P < 0.05), even though the growth-promoting activity of denuded GM -/- oocytes was found to be equivalent to that of wild-type oocytes. GM-CSF deficiency was associated with marginally increased DNA synthesis in cumulus cells and significantly (P < 0.05) lower progesterone production by mural granulosa cells recovered from GM -/- compared with those recovered from GM +/+ mice. The addition of rec-mGM-CSF in vitro did not affect DNA synthesis in either cell type or progesterone production by mural granulosa cells, irrespective of GM-CSF status. There was no effect of GM-CSF deficiency on the capacity of FSH and insulin-like growth factor I to stimulate DNA synthesis in cumulus-oocyte complexes (approximately 15- and threefold, respectively) and in mural granulosa cells (approximately two- and threefold, respectively). Taken together, these data show that GM-CSF influences events associated with follicular maturation in mice. The effects of GM-CSF are not exerted directly in granulosa or cumulus cells, but appear to be mediated indirectly, perhaps through the agency of steroidogenesis-regulating secretions of local macrophage populations residing in the theca.

Analysis of Variance↗
PubMed1999

Effects of cerebrospinal fluid from patients with Parkinson disease on dopaminergic cells.

BACKGROUND: The pathogenesis of substantia nigra pars compacta neuronal injury in Parkinson disease (PD) remains unknown. Cerebrospinal fluid (CSF) has been reported to contain factors toxic to dopaminergic neurons. OBJECTIVES: To determine whether the cytotoxic effects of CSF of PD patients are specific for dopaminergic neurons, dependent on prior levodopa therapy, and mediated by the cytokine tumor necrosis factor alpha (TNF-alpha). DESIGN: Specimens of CSF were evaluated in dopaminergic (MES 23.5) and nondopaminergic (N18TG2) cell lines for cytotoxicity by viability assay and by the inhibition of tyrosine hydroxylase. After specificity and time and dose response were established, CSF specimens were assayed in a blinded manner. The TNF-alpha levels in CSF were determined by enzyme-linked immunosorbent assay. The toxicity of TNF-alpha in MES 23.5 cells was determined. SETTING: A university-based research facility. SUBJECTS: There were 4 groups of subjects: normal control subjects (n = 10), control subjects with neurologic disease (n = 8), PD patients treated with levodopa (n = 10), and untreated subjects with PD (n= 20). RESULTS: Specimens of CSF from 15 (50%) of 30 PD patients and 2 (11%) of 18 control subjects were cytotoxic to dopaminergic MES 23.5 cells and were nontoxic to the parental cell line N18TG2. There was no correlation between the degree of PD CSF cytotoxicity, levodopa therapy, or the severity and duration of PD. Terminal deoxynucleotidyl transferase-mediated biotin-deoxyuridine triphosphate nick-end labeling (TUNEL) for DNA fragmentation suggested the involvement of apoptotic mechanisms. The inhibition of tyrosine hydroxylase was an early effect of cell injury by PD CSF and correlated with the viability assay. The mean TNF-alpha level was 2.6-fold higher in CSF specimens from PD patients than in those of controls. The addition of recombinant human TNF-alpha equivalent to the highest level determined in PD CSF was not cytotoxic to MES 23.5 cultures. CONCLUSIONS: Blinded CSF specimens from PD patients, regardless of therapy, contain factors that cause specific dopaminergic neuronal cell injury. These factors are present in a substantial proportion of CSF specimens from patients with early PD, before the institution of medical therapy. Levels of TNF-alpha are elevated in the CSF of PD patients, but TNF-alpha is not responsible for the cytotoxicity.

Aged↗
PubMed1999

Neuroprotection by pramipexole against dopamine- and levodopa-induced cytotoxicity.

Pramipexole, a novel non-ergoline dopamine (DA) agonist, has been applied successfully for treatment of Parkinson's disease (PD). We report here that pramipexole can protect dopaminergic cell line Mes23.5 against dopamine- and levodopa-induced cytotoxicity possibly through a mechanism related to antioxidant activity. In the MES 23.5 cultures, DA and L-DOPA induce a dose- and time-dependent cytotoxicity, as determined by tetrazolium salt and trypan blue assays. Furthermore, an in situ terminal deoxynucleotidyl transferase assay demonstrates that DA-induced cell death is apoptotic. Pretreatment with pramipexole in a concentration range (4-100 microM) significantly attenuates DA- or L-DOPA-induced cytotoxicity and apoptosis, an action which is not blocked by D3 antagonist U-99194 A or D2 antagonist raclopride. Pramipexole also protects MES 23.5 cells from hydrogen peroxide-induced cytotoxicity in a dose-dependent manner. In cell-free system, pramipexole can effectively inhibit the formation of melanin, an end product resulting from DA or L-DOPA oxidation. These results indicate that pramipexole exerts its neuroprotective effect possibly through a mechanism, which is independent of DA receptors but related to antioxidation or scavenging of free radicals (e.g. hydrogen peroxide). As a direct DA agonist and potentially neuroprotective agent, pramipexole remains attractive in the treatment of PD.

Animals↗
PubMed1998

Antibodies from patients with Parkinson's disease react with protein modified by dopamine oxidation.

To determine whether specific antibodies are present in PD, we used an enzyme-linked immunosorbant assay (ELISA) that identifies increased immunoglobulin (IgG) levels towards a synthetic substrate prepared by incubating ovalbumin with dopamine and copper sulfate. Altered absorption spectrum and specific chemical detection demonstrated quinone modification of the ovalbumin. This modified protein was demonstrated to react with serial dilutions of PD sera. A threshold dilution of 1:500 was subsequently used to screen sera from patients with PD (n = 21), amyotrophic lateral sclerosis (n = 7), Alzheimer's disease (n = 7) and other neurological disease controls (n = 7). The assay produced a positive result in 7/21 PD patients and 0/21 disease controls (P < 0.02, Kruskal-Wallis test). Further testing of sera from untreated PD patients (n = 6) identified one positive sample. Thus, a subset of Parkinson's disease (PD) patients has immunoglobulin (IgG) to ovalbumin modified by dopamine oxidation. The presence of antibody reactivity to quinone-modified proteins could contribute to or amplify the inflammatory response in PD.

Aged↗
PubMed1987

Breakdown and quantitation of the forked termination of replication intermediate of Bacillus subtilis.

Using a procedure that minimizes shear forces, the BamHI-derived forked termination of replication intermediate of Bacillus subtilis, called band I DNA, can be extracted with little or no accompanying band II DNA. It has been shown that band II DNA is a product of band I breakdown. Nuclease P1-mediated breakdown of the forked band I DNA proceeds in two steps. The first causes the release of one of the arms as band II DNA; in the second step, the remaining arm is cleaved away to yield the free stem. It is concluded that band I represents the primary termination of replication intermediate. A quantitative assessment of the level of band I in DNA from cells of the merodiploid strain, GSY1127, growing at different rates has been made. For cells grown in a minimal medium, at least, the experimentally measured level of band I is of the order (approx. 60%) of that predicted for a complete block to movement of the clockwise fork at the replication terminus, terC.

Bacillus subtilis↗
PubMed1986

Nonrandom cosmid cloning and prophage SP beta homology near the replication terminus of the Bacillus subtilis chromosome.

From a library of Bacillus subtilis DNA cloned with the Escherichia coli cosmid vector pHC79, 85 recombinant cosmids containing DNA from near the replication terminus, terC, were identified. The DNA inserts of these cosmids were confined to three regions of a 350-kilobase segment of the chromosome extending from the left end of the SP beta prophage to approximately 75 kilobases on the right of terC. All B. subtilis genes known to reside in this segment, as well as the portion of the SP beta prophage that is expressed early in the lytic cycle of the phage, appeared to be absent from the library. A region of SP beta homology distinct from the prophage and just to the left of terC was identified.

Bacillus subtilis↗