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M R Hanson

Publications and source records attributed to M R Hanson.

At least 37 records · Page 2Linked to original sources
PubMed1997

Proposed algorithm to aid the diagnosis of cerebellopontine angle tumors.

Hearing and/or balance disorders are symptoms that may be associated with tumors of the cerebellopontine angle (CPA). Between March 1988 and May 1995, 22 patients had diagnosis or evaluation of CPA tumors at Cleveland Clinic Florida. The most common presenting signs or symptoms included unilateral low-frequency tinnitus, unsteadiness, and/or asymmetric hearing loss. On the basis of our experience, we have constructed an algorithm to help identify and manage acoustic nerve dysfunction. We compare our findings with national epidemiologic data and current medical reports.

Adult↗
PubMed1997

A heterologous maize rpoB editing site is recognized by transgenic tobacco chloroplasts.

Single nucleotides in plant chloroplast transcripts are edited from the genomically encoded C to U, often resulting in changes of the encoded protein sequence. Site-specific trans-acting factors are postulated to direct the selection of edited residues. In order to further define cis sequences required for RNA editing, we investigated whether two editing sites present in maize rpoB mRNA would be recognized by the editing machinery of transformed tobacco chloroplasts. A 93-nucleotide (nt) segment surrounding site I is sufficient to direct editing of the maize sequence in tobacco chloroplasts. However, an 86-nt segment surrounding maize site IV (which is genomically encoded as a T in tobacco) does not confer editing of this site, suggesting that trans-acting factors necessary for recognition of site IV are not present in tobacco. The maize sequences surrounding site I were found to compete with the endogenous rpoB for a depletable trans factor and to reduce editing of endogenous site I. The presence of exogenous maize site I was also found to decrease editing of endogenous tobacco site II, indicating that there is a shared aspect of editing for some closely spaced editing sites.

Base Sequence↗
PubMed1997

Cryostat tissue printing: an improved method for histochemical and immunocytochemical localization in soft tissues.

A modification of a previously described tissue print technique has been developed in which soft tissues are frozen and sectioned in a cryostat prior to direct collection on nitrocellulose or nylon membranes. The inexpensive embedding technique described here allows accurate orientation of specimens prior to mounting, and mounted material may be stored easily after initial sectioning for future reexamination. Standard hand tissue prints of soft specimens exhibit tissue distortion and uneven delivery of material to the membrane, which limits resolution and makes interpretation difficult. Cryostat sections retain tissue fragments in their original arrangement relative to each other during printing and deliver a consistent and quantitative amount of material from all parts of the specimen. The cryostat tissue print technique is applied here to immature floral buds, demonstrating the tissue-level histochemical localization of beta-glucuronidase in transgenic plants and immunolocalization of a novel protein present only in mutant plants. This modified technique is applicable for examining both plant and animal tissues.

Cryoultramicrotomy↗
PubMed1996

Fully edited and partially edited nad9 transcripts differ in size and both are associated with polysomes in potato mitochondria.

Two classes of nad9 transcripts are present at different abundances in the steady-state RNA pool of potato mitochondria. The 5'- and 3' termini of the transcripts were determined by primer extension and S1 nuclease protection analyses respectively. Using two primer pairs that will either specifically amplify the larger transcript or amplify both the larger and the smaller transcripts in RT-PCR analyses it was found that the larger nad9 transcripts are partially edited, while the smaller transcripts are fully edited. Both the larger and the smaller transcripts were found to be associated with mitochondrial polysomes. The polysome association was found to be sensitive to EDTA and puromycin treatment. Therefore, both fully and partially edited nad9 transcripts appear to be engaged in translation.

Base Sequence↗
PubMed1996

Preferential RNA editing at specific sites within transcripts of two plant mitochondrial genes does not depend on transcriptional context or nuclear genotype.

Transcripts of most plant mitochondrial protein-coding genes exhibit C-to-U RNA editing events. In Petunia, two co-transcribed genes, nad3 and rps12, exhibit transcripts which are not fully edited at all potential editing sites. We investigated the nad3/rps12 transcript population in four different genotypes. In one pair of genotypes, the nuclear genome is identical but the nad3/rps12 genes are in different transcriptional contexts. Both the nad3/ rps12 genes and the plant mitochondrial genomes are identical in a second pair of genotypes, but the nuclear background is derived from two different Petunia species. We found that the overall extent of editing varied greatly between genotypes and is affected by nuclear genotype but not by the global transcriptional context. Local sequence context around a particular site does affect editing frequency. In all genotypes, certain sites exhibit high editing frequency, but these sites do not share obvious primary sequence characteristics. In all genotypes examined, editing sites which do not affect the encoded amino acid are less frequently edited than sites which alter codons to non-synonymous forms. All these data indicate that an unidentified property of the sequences immediately surrounding a cytosine affect its selection as a target in the editing process.

Amino Acid Sequence↗
PubMed1996

Hypothalamic and plasma total nitrate/nitrite concentrations in spontaneously hypertensive rats.

Stable end-products of nitric oxide (NO) metabolism, nitrates and nitrites, were measured in hypothalamic extracts and plasma samples of Okamoto spontaneously hypertensive (SH) rats. The mean total nitrate/nitrite concentration was significantly lower in the hypothalami of SH rats compared with the normotensive Wistar Kyoto (WKY) control animals (P < 0.01). In contrast, their plasma concentrations were significantly higher (P < 0.05). These results indicate that the hypertensive state in SH rats is associated with a diminished production of hypothalamic NO, while the raised plasma nitrate/nitrite levels could reflect an increased compensatory endothelial NO synthase activity in these animals compared with the WKY controls.

Animals↗
PubMed1996

Protein polymorphism generated by differential RNA editing of a plant mitochondrial rps12 gene.

The rps12 gene transcripts encoding mitochondrial ribosomal protein S12 are partially edited in petunia mitochondria. Different petunia lines were found vary in the extent of rps12 transcript editing. To test whether multiple forms of RPS12 proteins are produced in petunia mitochondria as a result of partial editing, we probed mitochondrial proteins with specific antibodies against edited and unedited forms of a 13-amino-acid RPS12 peptide spanning two amino acids affected by RNA editing. Both antibodies reacted with mitochondrial proteins at the expected size for RPS12 proteins. The amounts of unedited RPS12 protein in different petunia lines correlate with the abundance of unedited transcripts in these plants. Unedited rps12 translation products are also detected in other plant species, indicating that polymorphism in mitochondrial rps12 expression is widespread. Moreover, we show that RPS12 proteins recognized by both edited-specific and unedited-specific antibodies are present in a petunia mitochondrial ribosome fraction. These results demonstrate that partially edited transcripts can be translated and that the protein product can accumulate to detectable levels. Therefore, genes exhibiting incompletely edited transcripts can encode more than one gene product in plant mitochondria.

Amino Acid Sequence↗
PubMed1995

Electrodiagnostic evaluation of fecal incontinence.

The aim of this study was to assess the utility of electrodiagnostic testing (EDT) for the evaluation of fecal incontinence (FI). Over a 5-year period, 225 patients (174 females) with FI were prospectively studied with anal manometry, anal ultrasonography, anal electromyography (AEMG), and pudendal nerve terminal motor latency (PNTML) assessment. The mean age was 60 (range 12-94) years. Causes of FI identified by clinical evaluation were obstetric injuries (45), rectal prolapse (43), iatrogenic or other trauma (42), neurologic disease (23), and idiopathic (72). EDT revealed abnormalities in 76% of patients. The incidence of pudendal neuropathy (PN) was 36% (bilateral 21%, unilateral 15%). Patients with PN were older than were those with normal PNTML (mean 71 vs. 63 years; P < 0.002). No relationship between squeeze pressure and PN could be demonstrated (P = 0.9). Reduced motor unit potential (MUP) recruitment on AEMG was present in 60% and was associated with decreased squeeze pressure (P < 0.001) and increased MUP polyphasia (P < 0.001). Concurrence of AEMG and anal ultrasonographic findings was observed in 35 of 41 patients (84%). Defects were overlooked in one study but identified by the other on three occasions, each. Moreover, 8 of 22 patients with demonstrated sphincter defects had unsuspected PN or extensive sphincter injury on AEMG that precluded sphincter repair. In conclusion, EDT proved to be a valuable tool in the evaluation and subsequent treatment of patients with FI.

Adolescent↗
PubMed1995

Expression of the CMS-associated urfS sequence in transgenic petunia and tobacco.

The expression of a 25 kDa protein, encoded by the fused mitochondrial pcf gene, is associated with cytoplasmic male sterility (CMS) in petunia. To investigate the role of the 25 kDa protein in CMS we have transformed petunia and tobacco plants with constructs expressing a portion of the urfS sequence of the pcf cDNA which encodes the 25 kDa protein. The urfS sequence was fused with two different mitochondrial targeting sequences. The chimeric gene coding region was placed under the control of the CaMV 35S promoter or a tapetum-specific promoter. Expression of the PCF protein was obtained in mitochondria of transgenic petunia and tobacco plants, yet fertility of the plants was not affected. Analysis of the location of the urfS-encoded protein revealed that it fractionates primarily into the soluble fraction in the transgenic plants whereas the genuine 25 kDa protein is found primarily in the soluble fraction but also in the membrane portion of immature buds from CMS petunia plants. Fertile transgenic plants were obtained which expressed the 25 kDa protein in the tapetal layer of post-meiotic anthers, while CMS plants express the endogenous 25 kDa protein in both the tapetal layer and sporogenous tissue of pre-meiotic anthers.

Amino Acid Sequence↗
PubMed1995

Pudendal neuropathy in evacuatory disorders.

PURPOSE: Aims of the present study were to assess frequency of pudendal neuropathy in patients with constipation and fecal incontinence, to determine its correlation with clinical variables, anal electromyographic assessment, and anal manometric pressures, and to determine usefulness of the pudendal nerve terminal motor latency assessment in evaluation of these evacuatory disorders. METHODS: From 1988 to 1993, 395 patients (constipated, 172; incontinent, 223) underwent pudendal nerve terminal motor latency, electromyography, and anal manometry. Pudendal neuropathy was defined as a pudendal nerve terminal motor latency greater than 2.2 ms. RESULTS: Patients were a mean age of 60.7 (range, 17-88) years. Overall incidence of pudendal neuropathy was 31.4 percent (constipated, 23.8 percent; incontinent, 37.2 percent; P < 0.05). Incidence of pudendal neuropathy dramatically increased after 70 years of age in both groups (22 percent vs. 44 percent; P < 0.05). Moreover, subjects with pudendal neuropathy were older than those without pudendal neuropathy (mean age, 67 vs. 57 years; P < 0.05). The presence of pudendal neuropathy was associated with decreased motor unit potentials recruitment in patients with incontinence (P < 0.01). Patients with and without pudendal neuropathy had a similar mean squeezing pressure in both groups. CONCLUSION: Pudendal neuropathy is an age-related phenomenon. Although pudendal neuropathy is associated with abnormal anal electromyographic findings in patients with incontinence, no association with anal manometric pressures was found. Pudendal nerve terminal motor latency assessment is a useful tool in the evaluation of patients with fecal incontinence, but its role in the assessment of constipated patients remains unknown.

Adolescent↗
PubMed1995

How do alterations in plant mitochondrial genomes disrupt pollen development?

Cytoplasmic male sterility arises when mitochondrial activities are disrupted that are essential for pollen development. Rearrangements in the mitochondrial genome that create novel open reading frames are strongly correlated with CMS phenotypes in a number of systems. The morphological aberrations which indicate CMS-associated degeneration are frequently restricted to the male sporogenous tissue and a limited number of vegetative tissues. In several cases, this tissue specificity may result from interactions between the mitochondrial genome and nuclear genes that regulate mitochondrial gene expression. A molecular mechanism by which CMS might be caused has not been conclusively demonstrated for any system. Several hypotheses for general mechanisms by which mitochondrial dysfunction might disrupt pollen development are discussed, based on similarities between the novel CMS-associated genes from a number of systems.

Cloning, Molecular↗
PubMed1995

Long-term follow-up of blood donors with indeterminate human immunodeficiency virus type 1 results on Western blot.

BACKGROUND: At present, tens of thousands of United States blood donors who are at low risk for human immunodeficiency virus type 1 (HIV-1) infection are indefinitely deferred. These persons are repeatably reactive for HIV-1 antibody in enzyme immunoassay (EIA) and are indeterminate in Western blot. STUDY DESIGN AND METHODS: To determine the significance and persistence of anti-HIV-1 reactivity in plasma from volunteer blood donors with HIV-1-indeterminate Western blots, 66 donors were retested for HIV-1 antibody by the same manufacturers' EIA and Western blot 5 to 7 years after the initial Western blot. In addition, donors' peripheral blood mononuclear cells were tested by polymerase chain reaction (PCR) for HIV-1 DNA gag sequences. RESULTS: Thirty-five (53%) of 66 donors were still repeatedly reactive for HIV-1 on EIA and indeterminate on Western blot, 23 (35%) were negative on EIA and indeterminate on Western blot, 7 (11%) were negative in EIA and Western blot, and 1 (2%) was repeatedly reactive on EIA and negative on Western blot. Donors with persistently indeterminate Western blots had a band pattern nearly identical to that on the original Western blot. No donor was positive in Western blot, p24 antigen, or PCR testing. No donor had signs or symptoms of HIV-1 infection. CONCLUSION: Long-term follow-up of Western blot-indeterminate blood donors does not reveal evidence of HIV-infection. A mechanism to return these donors to the donor pool should be considered.

Base Sequence↗
PubMed1995

A plant mitochondrial sequence transcribed in transgenic tobacco chloroplasts is not edited.

RNA editing occurs in two higher-plant organelles, chloroplasts and mitochondria. Because chloroplasts and mitochondria exhibit some similarity in editing site selection, we investigated whether mitochondrial RNA sequences could be edited in chloroplasts. We produced transgenic tobacco plants that contained chimeric genes in which the second exon of a Petunia hybrida mitochondrial coxII gene was under the control of chloroplast gene regulatory sequences. coxII transcripts accumulated to low or high levels in transgenic chloroplasts containing chimeric genes with the plastid ribosomal protein gene rps16 or the rRNA operon promoter, respectively. Exon 2 of coxII was chosen because it carries seven editing sites and is edited in petunia mitochondria even when located in an abnormal context in an aberrant recombined gene. When editing of the coxII transcripts in transgenic chloroplasts was examined, no RNA editing at any of the usual sites was detected, nor was there any novel editing at any other sites. These results indicate that the RNA editing mechanisms of chloroplasts and mitochondria are not identical but must have at least some organelle-specific components.

Amino Acid Sequence↗
PubMed1994

A novel anther-expressed adh-homologous gene in Lycopersicon esculentum.

Two novel tandemly-oriented open reading frames (ORFs) with homology to alcohol dehydrogenase (ADH) were isolated from tomato. The predicted amino acid composition for each of the two tandem adh genes indicates the presence of 22 and 21, respectively, of 22 amino acids conserved in ADH proteins from plants and animals. However, comparison to known plant adh genes reveals a significantly lower similarity indicating that they belong to a novel class of ADHs. According to mapping data, the adh-homologous ORFs do not represent either of the previously studied adh1 or adh2 genes of tomato. The tandem genes, termed adh3a and adh3b, mapped to a distal region of the long arm of chromosome 4, unlike adh1, which maps closer to the centromere. Adh3a and adh3b have over 90% similarity to each other at the nucleotide and putative peptide levels. The adh3a gene has ten exons and nine introns with the transcription initiation site 57 bp upstream of the translation start. A putative TATA box and polyadenylation site have been identified. Adh3a is transcribed and, according to cDNA sequence analysis, fully processed in the late stages of anther development. According to transformation analysis, tissue-specific regulatory elements reside within the -448 to +724 region. The termination codon of adh3a is separated from the putative adh3b translation start site by 789 bp of intervening sequence. The 5' untranscribed sequences of each gene contain a stretch of 68 bp with 78% similarity. Within this stretch are sequences which are homologous to sequences found in anaerobically-induced or pollen-expressed genes from various plant species.

Alcohol Dehydrogenase↗
PubMed1994

Role of pudendal nerve terminal motor latency assessment in constipated patients.

UNLABELLED: The importance of pudendal nerve terminal motor latency assessment for the evaluation of incontinence is well established. However, its role in constipated patients remains unclear. PURPOSE: The purpose of the present study was to assess the incidence of pudendal neuropathy in constipated patients and its correlation with others variables including age, sex, anal pressures, and anal electromyography. RESULTS: From 1988 to 1993, 161 patients with chronic constipation underwent pudendal nerve terminal motor latency assessment, anal electromyography, and anal manometry. The overall incidence of pudendal neuropathy was 23.6 percent; females and males had a similar incidence (24 percent vs. 23 percent, respectively; P > 0.05). Patients over 70 years old had a significantly higher incidence of pudendal neuropathy than did patients under 70 years (37 percent vs. 12 percent, respectively; P < 0.01). Patients with paradoxical puborectalis contraction on anal electromyographic assessment had a higher incidence of bilateral neuropathy, paradoxical puborectalis contraction (+)23 percent vs. paradoxical puborectalis contraction (-)8 percent, P < 0.05. Patients with pudendal neuropathy also had a higher incidence of decreased motor units potential recruitment than did patients without pudendal neuropathy (31.5 percent vs. 17 percent, respectively; P > 0.05). CONCLUSIONS: Pudendal nerve terminal motor latency assessment was able to detect unsuspected pudendal neuropathy in 24 percent of patients. This finding correlated with age and with the presence of paradoxical puborectalis contraction but not with manometric anal pressures, motor unit potentials recruitment, or the presence of polyphasia. However, the often espoused relationship between pudendal latency and external sphincter function could not be demonstrated.

Adolescent↗
PubMed1994

A single homogeneous form of ATP6 protein accumulates in petunia mitochondria despite the presence of differentially edited atp6 transcripts.

Transcripts encoding ATP synthase subunit 6 (ATP6) in petunia mitochondria were shown to be edited at 15 sites, leading to 14 amino acid changes. Certain sites are partially edited, including a site that introduces a new translation termination codon that is 13 codons upstream of the genomically encoded stop codon. Transcripts lacking the new stop codon are present in an approximately 2.5:1 ratio to transcripts carrying the stop codon created by RNA editing. To investigate whether partially edited transcripts are represented as proteins, we generated an antibody against a 12-residue peptide that is specific for translation products of unedited transcripts. This antibody did not recognize any ATP6 protein in either total mitochondrial protein preparations or ATP6 samples purified by organic solvent extraction and reverse phase HPLC procedures. According to analysis by mass spectrometry, only one form of ATP6 protein accumulates in mitochondria despite the presence of abundant partially edited transcripts. Partially edited atp6 transcripts were associated with ribosomes, suggesting that a screening mechanism(s) acts cotranslationally or post-translationally to exclude the expression of incompletely edited transcripts.

Amino Acid Sequence↗
PubMed1994

Sequencing, processing, and localization of the petunia CMS-associated mitochondrial protein.

The petunia mitochondrial fused gene (pcf), which is associated with cytoplasmic male sterility (CMS), is composed of sequences derived from atp9, coxII, and an unidentified reading frame termed urfS. Pcf transcripts are modified by editing at 11 sites. Codon usage and nearest neighbor analysis suggest that the urfS region is not derived originally from a plant mitochondrial coding region. Although the gene contains an open reading frame coding for a 43 kDa protein, a 25 kDa gene product has previously been identified (Nivison and Hanson, 1989). N-terminal sequencing revealed that the 25 kDa protein is encoded within the urfS portion of pcf and that its actual molecular mass is 19.5 kDa. Through pulse-chase labeling of protein in isolated mitochondria, the 25 kDa protein was found to be processed from a 43 kDa precursor protein representing the entire pcf gene sequence. Antibodies to synthetic peptides encoded by the atp9 and coxII portions of pcf recognized petunia ATP9 or COXII but no other mitochondrial proteins on immunoblots. Controlled proteolysis experiments showed that both the 43 kDa precursor and the 25 kDa protein are soluble or loosely associated with membranes. Thus, the 25 kDa protein appears to be the only pcf-encoded protein that accumulates in mitochondria.

Amino Acid Sequence↗