Ultrasound contrast agents.
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Contrast Media↗
Biomedical subjects
C M Allen
Publications and source records attributed to C M Allen.
pp60c-src enhances the acetylcholine receptor-dependent catecholamine release in vaccinia virus-infected bovine adrenal chromaffin cells.
Secretion of catecholamines by adrenal chromaffin cells is a highly regulated process that involves serine/threonine and tyrosine phosphorylations. The nonreceptor tyrosine kinase pp60c-src is expressed at high levels and localized to plasma membranes and secretory vesicle membranes in these cells, suggesting an interaction of this enzyme with components of the secretory process. To test the hypothesis that pp60c-src is involved in exocytosis, we transiently expressed exogenous c-src cDNA using a vaccinia virus vector in primary cultures of bovine adrenomedullary chromaffin cells. Chromaffin cells infected with a c-src recombinant virus restored the diminished secretory activity accompanying infection by wild type virus alone or a control recombinant virus. The level of enhanced catecholamine release correlated directly with the time and level of exogenous c-src expression. These results could not be attributed to differences in cytopathic effects of wild type versus recombinant viruses as assessed by cell viability assays, nor to differences in norepinephrine uptake or basal release, suggesting that pp60c-src is involved in stimulus-secretion coupling in infected cells. Surprisingly, exogenous expression of an enzymatically inactive mutant c-src also restored catecholamine release, indicating that regions of the introduced c-src protein other than the kinase domain may affect catecholamine release. Secretory activity was elevated by both forms of c-src in response to either nicotine or carbachol (which activate the nicotinic and the nicotinic/muscarinic receptors, respectively). In contrast, release of catecholamines upon membrane depolarization (as elicited by 55 mM K+) or by treatment with the calcium ionophore A23187 was unaffected by either vaccinia infection or increased levels of pp60c-src. These results suggest that pp60c-src affects secretory processes in vaccinia-infected cells that are activated through ligand-gated, but not voltage-gated, ion channels.
Adrenal Glands↗
Comparison of a lesion-inducing isolate and a non-lesional isolate of Candida albicans in an immunosuppressed rat model of oral candidiasis.
Two distinct strain-related patterns of organism-host interaction on dorsal tongue of immunocompetent rats have been identified for Candida albicans: some isolates induce mucosal lesions, while other isolates penetrate the keratin layer but do not produce a lesion. This study examined the behavior of each of the two types of isolates in a cyclosporin-immunosuppressed rat model. Groups B (normal) and D (cyclosporin) were orally inoculated with a lesion-inducing isolate of C. albicans, while a non-lesional isolate was given to Groups A (normal) and C (cyclosporin). A typical dorsal tongue lesion developed in 4/18 rats in Group B and in 13/16 in Group D (P = 0.00267). No significant difference in infection rate between the normal and cyclosporin-treated animals was seen for the non-lesional isolate. The lack of a host inflammatory response associated with the non-lesional isolate may represent an ecologic advantage for the organism.
Animals↗
Spontaneous development of a chromosomal translocation 5;14 in an Epstein-Barr-virus-associated B-cell lymphoma in a SCID mouse.
C.B-17 SCID mice were inoculated with human peripheral blood leukocytes (PBLs) from normal Epstein-Barr virus (EBV)-seropositive and -seronegative donors. Confirmation of a functioning human immune response was demonstrated by the detection of human antibody after inoculation with rotavirus, tetanus toxoid, or EBV. One group of animals inoculated with PBLs from an EBV-seropositive donor developed immunoblastic lymphomas approximately 9 weeks after transplantation. Confirmation of the species and sex of origin of the tumor cells was established using a spontaneous cell line prepared from the tumor. At passage I, the tumor-cell line (AGTI) showed 15% of the metaphases with a translocation involving chromosomes 5 and 14. A lymphoblastoid cell line (AGLCL) established from the same PBLs from the same donor at the time of inoculation of the mice had a normal female karyotype. The AGLCL and a clone of AGTI cells were analyzed for rearrangement of immunoglobulin heavy chain (IgH) genes; both cell lines showed rearrangement of both IgH alleles. The results outlined in this report suggest that a spontaneous chromosomal translocation involving chromosome 14 occurred in normal PBLs in the SCID mouse.
Animals↗
Conscious but paralysed: releasing the locked-in.
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Consciousness↗
Characterization of recombinant human farnesyl-protein transferase: cloning, expression, farnesyl diphosphate binding, and functional homology with yeast prenyl-protein transferases.
We have isolated cDNAs encoding the alpha and beta subunits of human farnesyl-protein transferase (FPTase). The proteins encoded by these two cDNAs are 93-95% identical to the corresponding subunits of bovine and rat FPTase and show regions of homology with proteins encoded by Saccharomyces cerevisiae prenyl-protein transferase genes. Human FPTase expressed in Escherichia coli from a translationally coupled operon had kinetic properties similar to those of FPTase isolated from bovine brain. Examination of farnesyl diphosphate binding indicated that while neither individual subunit was capable of isoprenoid binding, a radiolabeled farnesyl diphosphate analog could be specifically photo-cross-linked to the beta subunit of FPTase holoenzyme. To further analyze subunit structure-function and to detect functional similarities with yeast prenyl-protein transferases (FPTase and two geranylgeranyl-protein transferases), amino acid changes homologous to those found in mutant yeast prenyl-protein transferase subunits were made in the subunits of human FPTase. Substitutions in either the alpha or beta subunits that decrease the activity of yeast prenyl-protein transferases were also observed to impair human FPTase. Kinetic analyses showed that these mutant human FPTases have Km and kcat values that are altered with respect to wild-type human FPTase.
Alkyl and Aryl Transferases↗
Leiomyosarcoma metastatic to the oral region. Report of three cases.
Leiomyosarcoma, a malignant lesion of smooth muscle origin, is rare in the oral region. Metastatic leiomyosarcoma may originate from several potential primary sites, and the lung is the most common target tissue for metastatic deposits. This article describes three cases of leiomyosarcoma that were metastatic to the oral cavity and discusses the clinical and histopathologic differential diagnosis.
Aged↗
Paraneoplastic pemphigus. A distinct autoimmune vesiculobullous disorder associated with neoplasia.
A vesiculobullous disease termed paraneoplastic pemphigus with distinct autoantibodies was newly described in 1990. All reported cases have occurred in patients with a history of neoplasia, including lymphoma, chronic lymphocytic leukemia, poorly differentiated sarcoma, and benign thymoma. As in pemphigus vulgaris, intraepithelial clefts with acantholysis are noted histopathologically, and intercellular binding of immunoreactants is seen with direct immunofluorescence studies of mucous membrane and skin biopsies. However, immunoreactants may also be found along the basement membrane zone in paraneoplastic pemphigus. Indirect immunofluorescence using rat bladder epithelium as substrate shows an intercellular pattern that appears to be highly specific for paraneoplastic pemphigus. We report a patient with non-Hodgkins lymphoma of 8 years duration who developed severe erosive stomatitis and lichenoid dermatitis after receiving chemotherapy for a relapse of lymphoma. Her case illustrates the typical features of the disorder described as paraneoplastic pemphigus. Neoplasia-associated pemphigus may be a more precise term for this disorder because the course of the blistering eruption does not always parallel the course of the underlying cancer. The clinical features, histopathologic findings, and immunofluorescence findings of this unique syndrome are reviewed.
Aged↗
Verruciform xanthoma in a bone marrow transplant recipient.
The verruciform xanthoma is an uncommon benign condition of uncertain cause that affects either mucosa or, less commonly, skin. Most lesions are solitary, and most have been reported to involve the oral mucosa. In some instances, chronic damage to the lesional site has been identified. This report describes a verruciform xanthoma that developed on the lower vermillion zone of the lip of a young person who had undergone allogeneic bone marrow transplantation for acute lymphoblastic leukemia. To our knowledge, this is the first reported case of this lesion occurring in a bone marrow transplantation patient. We speculate that immunologically mediated damage to the patient's epithelium in this area may be related to the pathogenesis of the lesion.
Adult↗
Studies in red blood cell preservation. 7. In vivo and in vitro studies with a modified phosphate-ammonium additive solution.
Studies were conducted to examine whether an experimental additive solution (EAS-2) containing, in mM: 20 NH4Cl, 30 Na2HPO4, 2 adenine, 110 dextrose, 55 mannitol, pH 7.15, would be useful to extend the storage shelf life of human RBCs. With 6 pairs of split units, ATP concentrations were better maintained for 12 weeks with EAS-2 than with Adsol (1.8 vs. 1.1 mumol/g Hb, respectively, p = 0.002). Autologous 24-hours 51Cr viability values for split units in the same donors were: on 6 paired units at 8 weeks, EAS-2 87.0 +/- 4.5%, Adsol 72.6 +/- 2.3%, p = 0.004; on 11 paired units at 9 weeks, EAS-2 79.5 +/- 7.1%, Adsol 68.2 +/- 10.1%, p = 0.0003. The data suggest that packed RBCs stored for 9 weeks with EAS-2 will be suitable for transfusion following the removal of supernatant with a single washing step.
Adenine↗
Amplification of the bacA gene confers bacitracin resistance to Escherichia coli.
An Escherichia coli genomic library was constructed in order to facilitate selection for genes which confer bacitracin resistance through amplification. One of the plasmids from the library, plasmid pXV62, provided a high level of bacitracin resistance for E. coli. Deletion and nucleotide sequence analyses of bacitracin resistance plasmid pXV62 revealed that a single open reading frame, designated the bacA gene, was sufficient for antibiotic resistance. The bacA gene mapped to approximately 67 min on the E. coli chromosome by proximity to a previously mapped locus. The deduced amino acid sequence of the bacA-encoded protein suggests an extremely hydrophobic protein of 151 amino acids, approximately 65% of which were nonpolar amino acids. E. coli cells containing plasmid pXV62 have increased isoprenol kinase activity. The physical characteristics of the deduced protein and enhanced lipid kinase activity suggest that the bacA gene may confer resistance to bacitracin by phosphorylation of undecaprenol.
Amino Acid Sequence↗
MR cholangiography: clinical evaluation in 40 cases.
PURPOSE: To determine the reliability and efficacy of magnetic resonance (MR) cholangiography in demonstrating the site and extent of stricture. MATERIALS AND METHODS: In 40 patients with obstructive jaundice, three-dimensional MR cholangiography was performed with a sequence of mirrored fast imaging with steady-state precession and was compared with conventional cholangiography in 39 cases. The level of obstruction was determined by examining all imaging data available. RESULTS: Diagnostic MR cholangiograms were acquired in 39 patients; absence of obstruction was confirmed in three, and obstruction was seen in 36. The level of obstruction or absence of obstruction was accurately shown in 36 of 40 patients with MR cholangiography and in 37 of 39 patients with conventional cholangiography. The peripheral biliary tree was shown more completely with MR cholangiography than with endoscopic retrograde cholangiography in all 32 patients undergoing diagnostic studies with both modalities. CONCLUSION: Three-dimensional MR cholangiography shows particular promise for the assessment of complex strictures, in which conventional cholangiography carries a higher risk of sepsis, for planning optimal drainage before intervention.
Adult↗
3-dimensional reconstruction of ultrasound images of the uterine cavity.
We report our experience of 3-dimensional (3-D) reconstruction of ultrasound images of the uterine cavity. This is the first time that mapping of the contours of the uterine cavity with 3-D reconstruction has been achieved using standard clinical equipment for image acquisition. Ultrasound contrast hysterography was performed on 10 patients using both negative and positive intrauterine contrast media. 3-D image acquisition was performed during uterine cavity distension. The manipulation of the 3-D data sets is described and examples are shown. We believe that in some circumstances 3-D reconstructed images may be easier to interpret than 2-dimensional ultrasound images. We anticipate that this new technique will have a role in the preoperative assessment of uterine fibroids and endometrial polyps.
Adult↗
Ultrasound contrast hysterosalpingography--evaluation as an outpatient procedure.
Ultrasound contrast hysterosalpingography (HSG) uses intrauterine contrast media to increase the diagnostic value of plain transvaginal ultrasound enabling the uterine cavity contour to be assessed and allowing tubal patency to be determined. We present our experience using both negative (sterile saline) and positive (Echovist, Schering) contrast media in 27 patients presenting with a wide range of gynaecological disorders. This is the first report comparing the use of the two contrast media with plain ultrasound on a purely outpatient basis. We have found ultrasound saline HSG to be superior for the delineation of the uterine cavity and we predict that this will become a first line investigation for assessing the configuration of the uterine cavity. However, although Echovist could be demonstrated flowing through patent fallopian tubes, we found ultrasound contrast HSG to be insufficiently accurate in the determination of tubal patency and do not feel that it can replace conventional X-ray HSG. We review the literature on this technique and discuss its future role in gynaecological imaging.
Adult↗
Fibric acid derivatives: effects on the synthesis of isoprenoid lipids in cultured human lymphocytes.
Fibric acid derivatives have been demonstrated to reduce circulating lipoprotein and triacylglycerol concentrations and to inhibit hydroxymethylglutaryl CoA reductase, a key regulatory enzyme of cholesterol biosynthesis. This study describes the effect of four fibric acid derivatives on the biosynthesis of isoprenoid products from acetate and mevalonate in Molt-4 cells, a human leukemic T-lymphocyte cell line. The isoprenoids analyzed were cholesterol as well as dolichol and ubiquinone, alternative products of the branched isoprenoid biosynthetic pathway. None of the fibric acid derivatives showed significant effects on the synthesis of cholesterol from acetate or mevalonate and there was little change in the flux of these metabolites into either dolichol and ubiquinone compared to cells grown in drug-free medium. Therefore, in contrast to the reported inhibitory effects of fibric acids on hepatic sterol synthesis in rats and humans and on hydroxymethylglutaryl CoA reductase activity in human nonmalignant lymphocytes, our results show that these drugs do not significantly affect any of the post-reductase enzymes in the branched metabolic pathways leading from acetate to dolichol, ubiquinone and cholesterol in short term culturing of human malignant lymphocytes.
Acetates↗
Central odontogenic fibroma, WHO type. A report of three cases with an unusual associated giant cell reaction.
Three cases of central odontogenic fibroma, WHO type, that exhibited a prominent giant cell granuloma-like histopathologic component are described in this report. All three lesions occurred in women, and all were located in the mandibular premolar-molar region. One lesion recurred after conservative excision, and the recurrence displayed the two histologically distinct tissues of the original lesion. The authors think that this pathologic process does not represent a "collision lesion" but, instead, is a unique presentation of a central odontogenic fibroma, WHO type.
Adolescent↗
Diagnosing and managing oral candidiasis.
The red to white lesions of oral candidiasis are easily treated with any of several antifungal medications. But predisposing systemic conditions, such as diabetes mellitus or human immunodeficiency virus infection, should be ruled out as contributing factors.
Antifungal Agents↗
Inhibition of farnesyl transferases from malignant and non-malignant cultured human lymphocytes by prenyl substrate analogues.
Cytosolic prenyl transferases from two human lymphoid tissue-derived cell lines, IM-9 and Molt-4 cells, are shown to isoprenylate recombinant p21H-ras. Isoprenylation was inhibited by an N-acetylated pentapeptide (N-Ac-Lys-Cys-Val-Leu-Ser), c,t-farnesyl diphosphate, c,t,t-geranylgeranyl diphosphate, t,t,t-geranylgeranyl diphosphate and a photolabile farnesyl diphosphate analogue. c,t-Farnesyl and t,t,t-geranylgeranyl monophosphates were also effective inhibitors of the Molt-4 enzyme but not the IM-9 enzyme.
Alkyl and Aryl Transferases↗