PubMed Health⌕ Search

Biomedical subjects

E Harris

Publications and source records attributed to E Harris.

At least 19 recordsLinked to original sources
PubMed1996

The mouse Engrailed-1 gene and ventral limb patterning.

During vertebrate limb development, positional information must be specified along three distinct axes. Although much progress has been made in our understanding of the molecular interactions involved in anterior-posterior and proximal-distal limb patterning, less is known about dorsal-ventral patterning. The genes Wnt-7a and Lmx-1, which are expressed in dorsal limb ectoderm and mesoderm, respectively, are thought to be important regulators of dorsal limb differentiation. Whether a complementary set of molecules controls ventral limb development has not been clear. Here we report that Engrailed-1, a homeodomain-containing transcription factor expressed in embryonic ventral limb ectoderm, is essential for ventral limb patterning. Loss of Engrailed-1 function in mice results in dorsal transformations of ventral paw structures, and in subtle alterations along the proximal-distal limb axis. Engrailed-1 seems to act in part by repressing dorsal differentiation induced by Wnt-7a, and is essential for proper formation of the apical ectodermal ridge.

Animals↗
PubMed1996

Concentration and storage of biotin in the amphibian brain.

Prominent displays of endogenous biotin reactivity can be observed at specific locations in histochemical preparations of the forebrain and midbrain in the northern leopard frog (Rana pipiens) and common American toad (Bufo americanus). At the light microscopic level, the biotin reactivity appears in clusters of darkly stained puncta of either spherical or rodlike shape in the olfactory cortex, nucleus isthmi, and hypothalamus. With the electron microscope, the biotin reactive spheres are identified as neuronal varicosities and synaptic boutons and the rods as short segments of axons. Appropriate controls demonstrate that the punctate biotin-reactive structures are sites of concentration of biotin or a biotin analog in the processes of certain neurons. These data represent the first observation on the selective concentration of a vitamin in vertebrate neurons and suggest that biotin may have specialized functions in anatomically delimited areas of the central nervous system. Localization of the densest concentration of the biotin-reactive puncta in the dorsolateral prominence of the olfactory cortex may have relevance to the functional organization of the olfactory system. The distributions of biotin-reactive puncta were observed in laboratory-housed frogs and in wild toads captured in the summer months but were sparse or absent in batches of commercially obtained frogs examined immediately upon arrival in the laboratory. Systemic administration of biotin or biocytin hydrochloride did not alter the appearance or numbers of the biotin-reactive structures either in newly received or laboratory-housed frogs. These findings suggest that the capacity of the biotin-storage mechanism in the amphibian brain may be set by environmental factors and may be readily saturable from natural dietary or enteric sources.

Animals↗
PubMed1996

Tandem high-dose chemotherapy supported by hematopoietic progenitor cells yields prolonged survival in stage IV breast cancer.

The aim of this phase II study was to determine the feasibility of using two (tandem) courses of high-dose alkylating agents with bone marrow or peripheral blood progenitor cell support in women with stage IV breast cancer. Women with stage IV breast cancer who had achieved a CR or PR during conventional chemotherapy were enrolled in a phase II trial of high-dose cyclophosphamide 7500 mg/m2 and thiotepa 675 mg/m2 (C+T) followed within 180 days by high-dose melphalan (M) 140 mg/m2. Bone marrow and/or GM-CSF mobilized peripheral blood hematopoietic progenitor cells were used to support high-dose C+T and high-dose M. Twenty-seven women were enrolled in this trial. The median age was 45 years (range 32-56). The median PS was 0 and all patients had achieved either a CR (4/27, 15%) or PR (23/27, 85%) to conventional chemotherapy. All 27 women underwent high dose C+T. The predominant toxicities were mucositis (81%), and diarrhea (81%); two patients (7%) died from infectious complications. Following C+T, the median time to hematologic recovery for neutrophils (ANC > 500 cells/mu 1) was 12 days and for platelets (>20 000 cell/mu 1), 23 days. Following C+T, 18 of 22 patients received high dose M; the predominant toxicities were nausea, vomiting (70%), and mucositis (91%). The median time to hematologic recovery for the ANC was 13 days and for platelets, 18 days. The overall response after high dose C+T and high dose M was 67% (CR, 15/27 patients (56%) and PR* (complete resolution of all measurable disease but persistent lytic disease or positive bone scan) 3/27 patients (11%). With median follow-up of 24 months, the actuarial freedom from relapse or treatment failure is 56% at 24 months. At 30 months 56% of patients are alive. For patients who achieve a CR or PR* the actuarial freedom from relapse or treatment failure at 24 months is 88%. In women with stage IV breast cancer who attain a CR or PR to conventional chemotherapy, tandem high-dose chemotherapy with ABMT can lead to prolonged relapse-free survival.

Adult↗
PubMed1995

Gain-of-function mutations in a human calmodulin-like protein identify residues critical for calmodulin action in yeast.

A human epithelial cell-specific transcript (NB-1) encodes a calmodulin-like protein (hCLP), which is identical in length and 85% identical in amino acid sequence to authentic human calmodulin (hCaM). Although hCaM shares only 60% amino acid sequence identity with yeast calmodulin (CMD1 gene product), hCaM was able to substitute functionally for Cmd1 in yeast cells. In contrast, hCLP was unable to support either spore germination or vegetative growth in Cmd1-deficient yeast cells, even when stably expressed at a level at least an order of magnitude above that of hCaM. Thus, hCLP provides an indicator protein for discerning those residues that are critical for calmodulin function in vivo. In addition to 20 conservative amino acid replacements, hCLP differs from hCaM (and other vertebrate calmodulins that are able to complement a cmd1 null mutation) by only three nonconservative substitutions. Site-directed mutagenesis was used to convert these three positions back to residues more typical of those found in authentic calmodulins and to prepare all possible combinations of these three mutations, specifically: three single mutants (R58V, R112N, and A128E), three double mutants (R58V A128E, R112N A128E, and R58V R112N), and the triple mutant (R58V R112N A128E). The triple mutant and one of the double mutants (R58V A128E) were able to restore an apparently normal growth rate to a cmd1 delta strain, indicating that the altered hCLPs have acquired the ability to behave as functional calmodulins in yeast. The other two double mutants were able to support growth of Cmd1-deficient cells only weakly, but cells expressing the R112N A128E mutant grew noticeably better than those expressing the R58V R112N mutant. Remarkably, one single mutant (A128E), but not the other two single mutants, was also reproducibly able to support weak growth of a cmd1 delta strain. The properties of these gain-of-function, or neomorphic, mutations implicate E128, and to a lesser extent V58, as residues critical for calmodulin action in vivo. Molecular modeling of these positions within the structure of a Ca(2+)-calmodulin.peptide complex indicates that E128 projects directly into the central cavity occupied by the bound peptide. Thus, E128 may contribute a contact that is vital for the interaction of Cmd1 with one or more of the targets that are essential for yeast cell growth.

Amino Acid Sequence↗
PubMed1994

Copper deficiency secondary to a copper transport defect: a new copper metabolic disturbance.

We describe a 21-year-old man who developed copper deficiency manifested as a demyelinating neuropathy, chronic intestinal pseudo-obstruction, osteoporosis, testicular failure, retinal degeneration, and cardiomyopathy with a tortuous aorta. His serum copper was low and did not increase despite administration of large doses of intravenous copper sulfate. The ceruloplasmin level as measured by an antibody technique was normal, yet ceruloplasmin (Cp) oxidase activity was very low. The Cp amino acid sequence was normal. This suggests that the copper deficiency was caused by a defect in hepatic processing of copper for incorporation into Cp.

Adult↗
PubMed1994

Functional consequences in yeast of single-residue alterations in a consensus calmodulin.

A synthetic gene encoding a 'consensus' calmodulin (synCaM) was able to substitute for the Saccharomyces cerevisiae calmodulin gene (CMDI), even though synCaM is only 60% identical in primary amino acid sequence to yeast Cmd1. Twelve different synCaM mutants were also expressed in yeast. Seven of the 12 mutant synCaMs supported germination and growth of Cmd1-deficient spores. Five of the 12 mutant synCaMs were incapable of supporting germination of Cmd1-deficient spores and, of these, four were also incapable of supporting vegetative growth of Cmd1-deficient haploid cells. The five nonfunctional synCaM mutants were expressed at levels equivalent to, or higher than, the seven synCaM mutants that were able to substitute for Cmd1; thus, the inability to function was not simply due to inadequate expression or rapid degradation. All nonfunctional synCaM mutants shared a single charge reversal mutation in the central helix (E84K), which was found to be sufficient to confer the lethal phenotype. The ability of another mutant synCaM (S101F) to support growth of Cmd1-deficient cells was dependent on cell ploidy. Another mutant (K115Y) supported spore germination and vegetative growth, but not meiosis and sporulation. The terminal phenotype of cells lacking a functional calmodulin included a dramatic accumulation of polymerized microtubules.

Calmodulin↗
PubMed1994

How to produce moisture chamber eyeglasses for the dry eye patient.

BACKGROUND: Moisture chambers are prosthetic devices coupled to eyeglasses that slow the evaporation of the tears from the ocular surface. The need for moisture chamber glasses is most evident when a patient suffers from Sjögren's syndrome. This disease creates a pathologically dry eye from tear anomalies. Other ocular and systemic conditions can also cause a painfully dry eye. METHODS: The concept behind a moisture chamber is to significantly minimize the air flow over the ocular surface. The chamber provides a vapor barrier that functions passively to prevent tear evaporation. This is achieved by using a polyurethane plastic to produce a chamber contiguous with spectacles. RESULTS: The chamber provides a humid environment behind the eyeglass lens and in front of the eye surface. Before deciding to produce a moisture chamber, one should consider the extensive time consumption involved in the production of these facially contoured customized devices. CONCLUSIONS: It may take 3-6 hours for a technician who has not previously made a moisture chamber to construct the first one. As the proficiency increases, one may be able to streamline the process to approximately 3 hours. This approach was investigated because of the paucity of available information about the production of moisture chamber glasses and the acute need and benefit by pathological dry eye patients for these special glasses.

Dry Eye Syndromes↗
PubMed1994

Arthroscopic distal clavicle excision. Technique and early results.

Since 1941, distal clavicle excision has been a reliable technique for alleviating pain caused by acromioclavicular joint arthritis. Disadvantages of the procedure include permanent shoulder weakness, a lengthy recovery time ranging from weeks to months before useful function of the extremity returns, and lack of cosmesis. By modifying the standard portals used to perform arthroscopic subacromial decompression, the authors have successfully excised the distal clavicle of ten consecutive patients. Using this arthroscopic technique, the surgical time averaged approximately one hour 40 minutes, blood loss was negligible, and there were no complications. Operations were performed in an outpatient setting. Five of ten patients missed work only on the day of surgery, and seven of ten patients required no formal physical therapy. All ten patients achieved a good or excellent result on the UCLA. Shoulder Scale for short-term follow-up evaluation. Postoperative radiographs documented adequate bone resection in all cases. In experienced hands, arthroscopic distal clavicle excision is an excellent substitute for the "open" procedure.

Acromioclavicular Joint↗
PubMed1993

A developmentally regulated microsomal protein specific for the pigment epithelium of the vertebrate retina.

In the vertebrate retina, the retinal pigment epithelium (RPE) performs specific functions critical to the normal process of vision. Although some of these functions are well documented, molecular data are still scarce. Using the RPE-specific monoclonal antibody RPE9, raised against human RPE cells, we have identified a novel 65 kD protein, conserved in mammals, birds, and frogs. This RPE-specific protein was found to be nonglycosylated. It was most effectively solubilized in the presence of detergent suggesting that it is associated with the RPE cell membranes. Its partitioning in the detergent phase of Triton X-114 and its solubilization in 0.75 M and 1.0 M KCl suggest that it interacts with the membrane either through a polypeptide anchor or charged amino acids. Cell fractionation by differential solubilization and differential centrifugation demonstrated that the protein was preferentially associated with the microsomal membrane fraction, where it is the major protein. Developmental expression of this 65 kD protein was examined in neonatal rats. Morphologically well-differentiated RPE cells did not express the 65 kD protein at birth. However, expression was detectable at postnatal day 4, that is, one to two days before the photoreceptors develop their outer segments, suggesting that the expression of the 65 kD protein may be coordinated with other developmental events in the intact retina. This is further supported by the fact that RPE cells in confluent culture lose the expression of this protein within two weeks, while they maintain their characteristic epithelial morphology. Because of its specificity, its evolutionary conservation, and its timing of expression, it is possible that this protein may be involved in one of the key roles of RPE and as such is an important molecular marker for RPE differentiation.

Animals↗
PubMed1993

Heartwater in Guadeloupe and in the Caribbean.

A sero-epidemiological survey for heartwater was organized in 1992 in the Lesser Antilles, from Grenada to Saint Martin. Blood from about one percent of the ruminant livestock of the islands was randomly sampled and the sera were tested with an indirect ELISA. The percentage of positive sera was found to be 30% in Guadeloupe, 25% in Antigua, 2.2% in St.Martin, 1.3% in St. Kitts & Nevis, 3.8% in Montserrat, 1.7% in Dominica, 1.5% in St.Lucia, 1.5% in St.Vincent, 3.5% in Barbados, 2.9% in Grenada and 7% in Martinique. Ruminants from Guadeloupe and Antigua are known to be infected with heartwater. The low percentage of positive sera and the absence of clinical cases in the other islands strongly suggest that positive sera in these islands are probably due to non-specific cross reactions between Cowdria and other micro-organisms (possibly Ehrlichia) which remain to be isolated. In particular, the high percentages of positive sheep sera in Martinique (15%) and Montserrat (11%) should be further investigated.

Animals↗
PubMed1992

The homeodomain: a new face for the helix-turn-helix?

The discovery of conserved protein domains found in many Drosophila and mammalian developmental gene products suggests that fundamental developmental processes are conserved throughout evolution. Our understanding of development has been enhanced by the discovery of the widespread role of the homeodomain (HD). The action of HD-containing proteins as transcriptional regulators is mediated through a helix-turn-helix motif which confers sequence specific DNA binding. Unexpectedly, the well conserved structural homology between the HD and the prokaryotic helix-turn-helix proteins contrasts with their divergent types of physical interaction with DNA. A C-terminal extension of the HD recognition helix has assumed the role that the N-terminus of the prokaryotic helix plays for specification of DNA binding preference. However, the HD appears also capable of recognizing DNA in an alternative way and its specificity in vivo may be modified by regions outside the helix-turn-helix motif. We propose that this intrinsic complexity of the HD, as well as its frequent association with other DNA binding domains, explains the functional specificity achieved by genes encoding highly related HDs.

Amino Acid Sequence↗
PubMed1992

Early degenerative joint disease simulating impingement syndrome: arthroscopic findings.

Eighteen patients who underwent shoulder arthroscopy for impingement syndrome were shown at operation to have coexisting glenohumeral degenerative joint disease (DJD) which was not apparent during preoperative clinical and radiographic evaluation. Because traditional ("open") techniques of anterior acromioplasty do not allow inspection of the glenohumeral joint, it is almost certain that this pathology would have been missed at operation if open acromioplasty had been performed. We conclude that arthroscopic subacromial decompression (ASD), by allowing easy inspection of the glenohumeral joint, offers a distinct advantage over traditional acromioplasty. Furthermore, arthroscopic evaluation of some of these patients' glenohumeral joints provided us with evidence supporting the existence of subluxation arthropathy. We have also developed a new clinical test, the "compression-rotation" test, which has been helpful in distinguishing patients with both impingement syndrome and early DJD syndrome from those with isolated impingement syndrome. Although patients in this study appeared to be doing well at short-term follow-up status post-ASD and glenohumeral debridement, no long-term results are yet available.

Adult↗
PubMed1992

An in vitro investigation of the action of lamotrigine on neuronal voltage-activated sodium channels.

Lamotrigine (LTG), 6-(2,3-dichlorophenyl)-1,2,4-triazine-3,5-diamine, is a novel antiepieptic drug structurally unrelated to the major anticonvulsants in current use. Previous studies of LTG in rodents revealed efficacy in maximal electroshock test, pentylenetetrazol test and kindling models of seizures suggesting potential utility in the treatment of partial and generalized (tonic-clonic) seizures. In the present study, LTG was found to block sustained repetitive firing of sodium-dependent action potentials in mouse spinal cord cultured neurons and inhibit [3H]batrachotoxinin A 20-alpha-benzoate binding in rat brain synaptosomes suggesting a direct interaction with voltage-activated sodium channels.

Action Potentials↗
PubMed1992

Acetaminophen overdose as a suicidal gesture: a survey of adolescents' knowledge of its potential for toxicity.

Acetaminophen is a popular nonprescription analgesic that is often taken in overdose by adolescents during suicidal gestures. The authors hypothesized that most adolescents are naive about the toxic and lethal potential of acetaminophen in overdose. A one-page, 12-item questionnaire was administered to 169 high school students to evaluate their perceptions and knowledge in this area. Whereas only 22% of the sample underestimated the dose of acetaminophen necessary to cause harm, 40.5% underestimated the potential lethality of acetaminophen in overdose. Moreover, 17% of the sample did not believe one could ingest enough acetaminophen to cause death. The lack of knowledge about acetaminophen's potential dangerousness, its widespread availability, and an absence of early symptoms of hepatotoxicity make this medication highly dangerous to those adolescents who take it in overdose during parasuicidal behavior.

Acetaminophen↗
PubMed1992

Development of enzymes of glycolysis and gluconeogenesis in human fetal liver.

The activities of two key enzymes of glycolysis and two key enzymes of gluconeogenesis were measured in liver samples from 44 human fetuses ranging in gestational age from 20 weeks to term, from infants to 10 years and from adults from 21 to 58 years. Specific activities of both gluconeogenic enzymes, fructose-1,6-biphosphatase and phosphoenolpyruvate carboxykinase, increased throughout the period of fetal development examined, and rose to near adult levels after birth. The activities of both glycolytic enzymes, phosphofructokinase 1 and pyruvate kinase, were lower in fetal than in pediatric and adult samples. For both of these enzymes, there was a significant reduction in activity of livers from fetuses of 34-37 weeks' gestation. Both enzymes showed hyperbolic kinetics at 24 weeks' gestation, but this changed to sigmoid kinetics during the 34-37 weeks' period of low activity. The data indicate that during the last weeks of gestation, inhibition of the activities of these two glycolytic enzymes, coupled with the rise in the two gluconeogenic enzymes, may reflect a change in liver from a primarily glycolytic role in the first two trimesters to a gluconeogenic role shortly before birth.

Adult↗