Search PubMed⌕ Search

Biomedical subjects

M E Lewis

Publications and source records attributed to M E Lewis.

At least 73 records · Page 4Linked to original sources
PubMed1991

Non-radioactive detection of nerve growth factor receptor (NGFR) mRNA in rat brain using in situ hybridization histochemistry.

Radioactively labeled RNA probes in conjunction with in situ hybridization histochemistry have become a useful method for studying gene expression in the central nervous system. We used digoxigenin-labeled uridine triphosphate to synthesize cRNA probes for localization of nerve growth factor receptor (NGFR) mRNA in the rat basal forebrain. Detection of cells containing digoxigenin-labeled NGFR mRNA was accomplished using a digoxigenin antibody conjugated with alkaline phosphatase. NGFR mRNA-positive cells were distributed in three major cell groups in the basal forebrain: the medial septal nucleus, vertical and horizontal limbs of the diagonal band of Broca, and nucleus basalis. This technique provides a rapid and sensitive method for high-resolution detection of mRNA species in the central nervous system, as well as the potential for co-localization of two different mRNA species within individual cells.

Animals↗
PubMed1990

Wilms' tumour: a 30 year experience at Wellington Hospital.

Over the 30 year period from 1958-88, 20 cases of Wilms' tumour have been treated at Wellington Hospital. All eight patients presenting prior to 1976 have died. The 12 patients presenting after 1976 were treated according to the guidelines of the National Wilms' Tumour Study Group and ten of these are alive (mean follow up seven years). Four of the patients received preoperative chemotherapy and this was found to facilitate surgical removal of the tumour. The concept of partial nephrectomy in the management of Wilms' tumour is discussed. Retrospective analysis of this series has shown that this would have been a feasible management option in four of the cases reviewed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Anatomical localization of calmodulin mRNA in the rat brain with cloned cDNA and synthetic oligonucleotide probes.

Calmodulin is a small, acidic calcium-binding protein that regulates a number of calcium-dependent enzyme activities and is thought to be involved in neurotransmission. To begin to explore further the regulation of this important protein in the brain, we have cloned a rat calmodulin cDNA and designed an oligonucleotide probe based on this sequence. Both the cDNA and oligonucleotide probes revealed a markedly heterogeneous distribution of hybridization signal for calmodulin mRNA in the rat brain. The greatest apparent abundance of mRNA for calmodulin was seen in the hippocampus and cerebral cortex, whereas many brain regions showed relatively low hybridization signal, including the striatum and portions of the hypothalamus and brainstem.

Animals↗
PubMed1990

Localization of nerve growth factor receptor mRNA in the rat basal forebrain with in situ hybridization histochemistry.

1. In situ hybridization histochemistry was used to localize nerve growth factor receptor (NGFR) mRNA in the adult rat basal forebrain. 2. In emulsion-dipped sections 35S-labeled RNA antisense probes produced a high density of silver grains over cells located in the medial septum, vertical and horizontal limbs of the diagonal band of Broca, and nucleus basalis. 3. This distribution of NGFR mRNA overlaps with the distribution of NGFR protein localized using immunocytochemical techniques. 4. No hybridization signal was detected when sections were hybridized with a 35S-labeled RNA sense (control) probe. 5. We suggest that NGFRs are synthesized in these basal forebrain nuclei and transported to terminal areas where NGF is thought to be bound and internalized, an initial step in the many actions of this neurotrophic factor.

Animals↗
PubMed1989

Neuronal localization of cholecystokinin mRNA in the rat brain by using in situ hybridization histochemistry.

The distribution of cholecystokinin (CCK) mRNA in the rat brain was determined by means of in situ hybridization histochemistry. Our results demonstrate a widespread distribution of neurons containing CCK mRNA throughout the rat brain. Hybridization-positive neurons were distributed throughout the neocortex, olfactory bulb, claustrum, amygdala, the dentate gyrus and hippocampus proper, and several subnuclei of the thalamus and the hypothalamus. The most abundant and most heavily labeled neurons were found in the endopiriform/piriform cortex, tenia tecta, and the ventral tegmental area. The distribution of neurons positive for CCK mRNA paralleled that of CCK-like immunoreactive neurons. These results detail the distribution of CCK mRNA and clearly identify the existence of CCK-synthesizing neurons in regions such as the paraventricular and supraoptic nuclei of the hypothalamus, where the presence of CCK cell bodies was previously uncertain.

Amino Acid Sequence↗
PubMed1988

Neuronal localization of prosomatostatin mRNA in the rat brain with in situ hybridization histochemistry.

Individual neurons containing prosomatostatin mRNA were identified with in situ hybridization histochemistry. Our results demonstrate a widespread distribution of prosomatostatin mRNA in several regions of the rat central nervous system. Neurons containing this transcript were most abundant in the anterior olfactory nucleus, hypothalamus, hippocampus, and amygdala as well as in all regions of the cerebral cortex. Moreover, the distribution of mRNA-containing perikarya was coextensive with the location of neurons containing somatostatin-like immunoreactivity in all areas of the brain examined. Somatostatin neurons varied in their morphology and amount of hybridization signal from region to region. The widespread distribution and regional variations in neuronal morphology and the amount of hybridization signal are consistent with a neurotransmitter and/or a neuromodulator role for somatostatin in addition to its well-established neuroendocrine role. These results demonstrate that both the peptide and its mRNA are found in perikarya in the same areas and that they are therefore the sites of synthesis for somatostatin.

Amino Acid Sequence↗
PubMed1988

Recent developments in the use of synthetic oligonucleotides for in situ hybridization histochemistry.

Synthetic oligonucleotides have been used with increasing frequency as probes for the detection and study of the regulation of specific mRNAs by in situ hybridization histochemistry. These probes can be easily obtained and used by the nonmolecular biologist, and they have been shown to be effective for the study of a wide range of mRNAs in neuronal and neuroendocrine tissues. Considerations in oligonucleotide probe design, synthesis, purification, and labeling are described in this article, and current procedures for tissue preparation and hybridization are discussed. In addition, control procedures and methods for the quantitation of in situ hybridization by image analysis are discussed. Finally, the combination of this technique with immunocytochemistry and retrograde tract-tracing is reviewed. The coupling of quantitative in situ hybridization with other neuronal markers, e.g., of connectivity, provides an increasingly valuable technology for exploring the regulation of gene expression in a rich anatomical context.

Animals↗
PubMed1987

Quantitation of cellular resolution in situ hybridization histochemistry in brain by image analysis.

A new method for relative quantitation of mRNA levels with single neuron resolution is described. Hybridized tissue sections are emulsion dipped, exposed, and developed. The resulting silver grains are visualized using dark-field microscopy at high magnification. The method relies on computer-based image analysis of sequentially located, high resolution, small fields containing the cell images, each of which is analyzed for mRNA content. Maps of cell distributions are constructed, with cell marks color-coded for relative mRNA levels, yielding previously unavailable information on regional distribution of quantitative cellular expression of specific mRNA in brain.

Brain Chemistry↗
PubMed1987

Autoradiographic differentiation of mu, delta, and kappa opioid receptors in the rat forebrain and midbrain.

While there is an abundance of pharmacological and biochemical evidence to suggest the existence of multiple opioid receptors, their precise localization within the brain is unclear. To help clarify this issue, the present study examined the distributions of the mu, delta, and kappa opioid receptor subtypes in the rat forebrain and midbrain using in vitro autoradiography. Mu and delta receptors were labeled with the selective ligands 3H-DAGO (Tyr- D-Ala-Gly-MePhe-Gly-ol), and 3H-DPDPE (D-Pen2, D-Pen5-enkephalin), respectively, while the kappa receptors were labeled with 3H-(-)bremazocine in the presence of unlabeled DAGO and DPDPE. Based on previous findings in our laboratory, the labeling conditions were such that each ligand selectively occupied approximately 75% of each of the opioid sites. The results demonstrated that all 3 opioid receptor subtypes were differentially distributed in the rat brain. Mu binding was dense in anterior cingulate cortex, neocortex, amygdala, hippocampus, ventral dentate gyrus, presubiculum, nucleus accumbens, caudate putamen, thalamus, habenula, interpeduncular nucleus, pars compacta of the substantia nigra, superior and inferior colliculi, and raphe nuclei. In contrast, delta binding was restricted to only a few brain areas, including anterior cingulate cortex, neocortex, amygdala, olfactory tubercle, nucleus accumbens, and caudate putamen. Kappa binding, while not as widespread as observed with mu binding, was densely distributed in the amygdala, olfactory tubercle, nucleus accumbens, caudate putamen, medial preoptic area, hypothalamus, median eminence, periventricular thalamus, and interpeduncular nucleus. While all 3 opioid receptor subtypes could sometimes be localized within the same brain area, their precise distribution within the region often varied widely. For example, in the caudate putamen, mu binding had a patchy distribution, while delta and kappa sites were diffusely distributed, with delta sites being particularly dense ventrolaterally and kappa sites being concentrated ventromedially. These results support the existence of at least 3 distinct opioid receptors with possibly separate functional roles.

Animals↗