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Biomedical subjects

P Carroll

Publications and source records attributed to P Carroll.

At least 73 records · Page 4Linked to original sources
PubMed1997

Deletion of chromosome 11p15, p12, q22, q23-24 loci in human prostate cancer.

Loss of heterozygosity (LOH) on chromosome 11 is frequently altered in various epithelial cancers. The present study was designed to investigate LOH on chromosome 11 in microdissected samples of normal prostatic epithelium and invasive carcinoma from the same patients. For this purpose, DNA was extracted from the microdissected normal and tumor cells of 38 prostate cancers, amplified by polymerase chain reaction PCR and analyzed for LOH on chromosome 11 using 9 different polymorphic DNA markers (D11S1307, D11S989, D11S1313, D11S898, D11S940, D11S1818, D11S924, D11S1336 and D11S912). LOH on chromosome 11 was identified in 30 of 38 cases (78%) with at least one marker. Four distinct regions of loss detected were: 1) at 11p15, at loci between D11S1307 and D11S989; 2) at 11p12, on locus D11S131 (11p12); 3) at 11q22, on loci D11S898, D11S940 and D11S1818; and 4) at 11q23-24, on loci between D11S1336 and D11S912. We found 25% of the tumors with LOH at 11p15; 39% had LOH at 11p12; 66% had LOH at 11q22; and 47% had LOH at 11q23-24. These deletions at 11p15, 11p12, 11q22 and 11q23-24 loci were not related to the stage or grade of the tumor.

Alleles↗
PubMed1997

Reduced size of retinal ganglion cell axons and hypomyelination in mice lacking brain-derived neurotrophic factor.

While brain-derived neurotrophic factor (BDNF) delays the death of axotomized retinal ganglion cells in rodents, it is unclear if it affects any aspect of the normal development of these cells. Here we examined the optic nerve of bdnf-/- mice. Axonal numbers were normal, but their diameter, as well as the proportion of myelinated axons, was reduced at postnatal day 20 (P20). In contrast, the facial nerve was not hypomyelinated. Expression levels of mRNAs coding for the myelin proteins PLP and MBP were substantially reduced in the hippocampus and cortex at P20, but not in the sciatic nerve. Intraventricular injections of BDNF into the ventricles of wild-type mice at P10 and P12 up-regulated expression of PLP in the hippocampus at P14. These results indicate a role of BDNF, discussed as indirect, in the control of myelination in the central nervous system.

Animals↗
PubMed1997

Using pulse oximetry in the home.

As complex patients require more sophisticated nursing care and equipment to stay at home, home care nurses must be able to make detailed, objective assessments. Pulse oximetry provides a tool to objectively assess oxygenation in the home. This article reviews how pulse oximetry works, how to interpret the results based on the patient's blood oxygen-carrying capacity, and technical aspects of using pulse oximetry in the home, including sources of inaccuracy in measurements and basic troubleshooting. These pulse oximetry principles are applied in the home care setting in three case studies.

Adult↗
PubMed1997

Frequent homozygous deletion of cyclin-dependent kinase inhibitor 2 (MTS1, p16) in superficial bladder cancer detected by fluorescence in situ hybridization.

Deletion of all or part of chromosome 9 is a well-described genetic alteration in bladder tumors. It has been proposed that inactivation of a tumor-suppressor gene on chromosome 9 is an important event in tumor development. Recent reports have supported cyclin-dependent kinase inhibitor 2 (CDKN2, also known as MTS1, INK4, p16) at 9p21 as a candidate tumor-suppressor gene in solid tumors. However, the prevalence of CDKN2 mutations in primary bladder tumors has been controversial. Therefore, we applied gene-specific probes for CDKN2 and the interferon alpha gene (IFNA), also located at 9p21, to characterize further the genomic deletions at this locus in bladder cancer. Seventeen superficial (pTa or pT1) bladder tumor specimens were examined for gene deletion by fluorescence in situ hybridization. Dual-labeling hybridization with a repetitive pericentromeric probe for chromosome 9 and a gene-specific probe for CDKN2 was performed to characterize the gene copy number in relation to the chromosome 9 copy number on a cell-by-cell basis. Homozygous deletion for CDKN2 without homozygous IFNA deletion was found in 5 of 17 tumors tested. Both genes were deleted in one additional case, and one tumor showed deletion of IFNA without deletion of CDKN2. Homozygous deletion at the 9p21 locus was found only in tumors having monosomy for the chromosome 9 centromeric signal. These results indicate that the homozygous deletion of the CDKN2 gene is a frequent and early event in superficial bladder cancer.

Adult↗
PubMed1997

Writing and evaluating computer-based training programs.

Publishers are preparing for the hitech future and authors and editors need to also. Publishers know that book sales may be down in the future, while computer program sales are expected to increase. Most book publishers have added media divisions to position themselves for the future. Authors and editors can also shift from writing or editing books to developing computer-based training programs. This author tells you how to write, edit, or evaluate the new computer-based training programs.

Authorship↗
PubMed1996

Virus-mediated gene transfer into hippocampal CA1 region restores long-term potentiation in brain-derived neurotrophic factor mutant mice.

Long-term potentiation (LTP) has been shown to be impaired in mice deficient in the brain-derived neurotrophic factor (BDNF) gene, as well as in a number of other knockout animals. Despite its power the gene-targeting approach is always fraught with the danger of looking at the cumulative direct and indirect effects of the absence of a particular gene rather than its immediate function. The re-expression of a specific gene at a selective time point and at a specific site in gene-defective mutants presents a potent procedure to overcome this limitation and to evaluate the causal relationship between the absence of a particular gene and the impairment of a function in gene-defective animals. Here we demonstrate that the re-expression of the BDNF gene in the CA1 region almost completely restores the severely impaired LTP in hippocampal slices of BDNF-deficient mice. The results therefore provide strong evidence for the direct involvement of BDNF in the process of LTP.

Adenoviridae↗
PubMed1996

Cryptic physiological trophic support of motoneurons by LIF revealed by double gene targeting of CNTF and LIF.

BACKGROUND: The survival and differentiation of motoneurons during embryonic development, and the maintenance of their function in the postnatal phase, are regulated by a great variety of neurotrophic molecules which mediate their effects through different receptor systems. The multifactorial support of motoneurons represents a system of high security, because the inactivation of individual ligands has either no detectable, or relatively small, atrophic or degenerative effect on motoneurons. RESULTS: Leukaemia inhibitory factor (LIF) has been demonstrated to support motoneuron survival in vitro and in vivo under different experimental conditions. However, when LIF was inactivated by gene targeting, there were no apparent changes in the number and structure of motoneurons and no impairment of their function. The slowly appearing, relatively mild degenerating effects in motoneurons that resulted from ciliary neurotrophic factor (CNTF) gene targeting were substantially potentiated by simultaneous inactivation of the LIF gene, however. Thus, in mice deficient in LIF and CNTF, the degenerative changes in motoneurons were more extensive and appeared earlier. These changes were also functionally reflected by a marked reduction in grip strength. CONCLUSIONS: Degenerative disorders of the nervous system, in particular those of motoneurons, may be based on multifactorial inherited and/or acquired defects which individually do not result in degenerative disorders, but which become apparent when additional (cryptic) inherited disturbances or sub-threshold concentrations of noxious factors come into play. Accordingly, the inherited inactivation of the CNTF gene in a high proportion of the Japanese population may represent a predisposing factor for degenerative disorders of motoneurons.

Animals↗
PubMed1996

Brain-derived neurotrophic factor promotes the differentiation of various hippocampal nonpyramidal neurons, including Cajal-Retzius cells, in organotypic slice cultures.

Brain-derived neurotrophic factor (BDNF) is widely expressed in the central nervous system, where its function is poorly understood. The aim of this study was to investigate the effects of BDNF on the differentiation of hippocampal nonpyramidal neurons using organotypic slice cultures prepared from postnatal rats. The application of BDNF induced an increase in immunostaining for the microtubule-associated protein (MAP)-2 in non-pyramidal neurons of the stratum oriens. BDNF promotes the elongation of the dendrites of these neurons, as demonstrated by analysis after biocytin labeling. Calbindin-D- and calretinin-containing subgroups of nonpyramidal cells in the stratum oriens were responsive to BDNF but not to nerve growth factor, as shown by an increase in the number of neurons immunostained for these proteins. BDNF also induced an increase in neuropeptide Y immunostaining of stratum oriens neurons. In contrast, BDNF had no effect on parvalbumin immunostaining, despite the fact that these cells express the BDNF receptor trkB. In addition, BDNF increased calretinin immunoreactivity in Cajal-Retzius cells situated around the hippocampal fissure. The Cajal-Retzius neurons persisted in slices beyond the time at which they degenerate in vivo. However, BDNF is not required for the survival of these cells, because they also persisted in slices from BDNF knock-out mice. The present results indicate that BDNF exerts an effect on the morphology of stratum oriens nonpyramidal cells and their calcium-binding protein levels. BDNF also regulates the calretinin content of Cajal-Retzius cells but is not necessary for their survival.

Animals↗
PubMed1996

GABAergic stimulation regulates the phenotype of hippocampal interneurons through the regulation of brain-derived neurotrophic factor.

Gamma-Aminobutyric acid (GABA) switches from enhancing to repressing brain-derived neurotrophic factor (BDNF) mRNA synthesis during the maturation of hippocampal neurons in vitro. Interneurons do not produce BDNF themselves, but BDNF enhances their differentiation. Therefore, the question arose whether hippocampal interneurons regulate their phenotype by regulating BDNF expression and release from adjacent cells. The GABA(A) receptor agonist muscimol and BDNF increased the size and neuropeptide Y (NPY) immunoreactivity of hippocampal interneurons. However, GABAergic stimulation failed to increase NPY immunoreactivity in cultures from BDNF knockout embryos. At later developmental stages, when GABA represses BDNF synthesis, treatment with muscimol induced a decrease in cell size and NPY immunoreactivity of interneurons. Interneurons might thus control their phenotype through the regulation of BDNF synthesis in, and release from, their target neurons.

Animals↗
PubMed1996

Autocrine-paracrine regulation of hippocampal neuron survival by IGF-1 and the neurotrophins BDNF, NT-3 and NT-4.

In contrast to sympathetic and sensory neurons in the peripheral nervous system, the neurotrophic requirements for neurons in the central nervous system (CNS) have not been clearly identified. The inactivation of specific neurotrophic factors and their receptors by gene targeting has shown that there are no major changes in neuron numbers in the CNS. This suggests an overlap between the action of different neurotrophic factors in the brain during development. Here we have studied the survival of hippocampal neurons prepared from embryonic rats using different culture conditions. Whereas the hippocampal neurons survive well in culture when plated at high density, they die at lower cell densities in the absence of appropriate neurotrophic factors. Under the latter conditions, both insulin-like growth factor-1 (IGF-1) and neurotrophins - brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4) - rescued a large proportion of cultured neurons. In addition, hippocampal neurons from BDNF knockout mice exhibited enhanced cell death compared with cells from wild-type animals. BDNF and IGF-1 both increased the survival of the hippocampal neurons lacking BDNF, showing complementary action for these factors in supporting survival. Blocking antibodies against NT-3 and IGF-1 decreased hippocampal neuron survival at low cell densities, showing autocrine or paracrine action of the factors. At higher cell densities, however, the antibodies had no effect, demonstrating that there is a sufficient amount of endogenous factors in supporting survival. Blocking antibodies against NT-3 and IGF-1 decreased hippocampal neurons depend for survival on local neurotrophic factors such as IGF-1, BDNF and NT-3, which act in an autocrine/paracrine manner. The multifactorial support of hippocampal neurons ensures a maximal degree of neuron survival even in the absence of an individual factor

Animals↗
PubMed1996

Three-dimensional H-1 MR spectroscopic imaging of the in situ human prostate with high (0.24-0.7-cm3) spatial resolution.

PURPOSE: To evaluate if three-dimensional hydrogen-1 magnetic resonance spectroscopic imaging (3D MRSI) when combined with a clinical MR imaging examination could discriminate prostatic adenocarcinoma from normal prostatic zonal anatomy and benign prostatic hyperplasia (BPH) on the basis of observable metabolite levels. MATERIALS AND METHODS: Combined phased-array, endorectal MR imaging and 3D MRSI was performed in nine young healthy volunteers, five patients with BPH, and 85 patients with prostate cancer and BPH. Volume MR imaging and 3D MRSI data were analytically corrected for the reception profile of the endorectal and pelvic phased-array coils, aligned with the MR imaging data, and compared with postoperative pathologic histology findings. RESULTS: Statistically significant variations in metabolite levels with prostatic zonal anatomy, age, and pathologic condition were detected with a 3D MRSI examination added to a clinical MR imaging examination. Significantly higher choline levels and significantly lower citrate levels were observed in regions of cancer compared with BPH and normal peripheral zone tissues. The ratio (choline + creatine/citrate) in regions of cancer (2.1 +/- 1.3 [standard deviation]) had no overlap with normal peripheral zone values and minimal overlap with BPH values (0.61 +/- 0.21). An estimate of the spatial extent of prostate cancer was determined by generating metabolite images in which this metabolite ratio significantly exceeded normal peripheral zone values in multiple contiguous sections. CONCLUSION: These results suggest that a 3D MRSI examination added to a clinical MR imaging examination may help define the presence and spatial extent of prostate cancer.

Adenocarcinoma↗