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Biomedical subjects

G Armstrong

Publications and source records attributed to G Armstrong.

At least 55 records · Page 3Linked to original sources
PubMed1992

Ring chromosomes in a retroperitoneal lipoma of childhood.

We report here the presence of ring chromosomes in a retroperitoneal lipoma from a 12-year-old male. Ring chromosomes are strongly associated with the pathological subtype "atypical lipoma" in adults. In contrast, however, the tumour described here possesses no atypical features.

Aneuploidy↗
PubMed1991

Verotoxin-resistant cell clones are deficient in the glycolipid globotriosylceramide: differential basis of phenotype.

Escherichia coli-derived verotoxin is an extremely toxic protein and is highly selective toward certain primate cells. Two susceptible cell lines are the Daudi cell line (human Burkitt lymphoma) and the Vero cell line (Green African monkey kidney). Both of these cell lines contain significant levels of the verotoxin binding glycolipid globotriosylceramide (Gb3) (1 nmol/10(7) cells and 3 nmol/10(6) cells, respectively). A clone was selected from the Vero cell line for resistance to Verotoxin 2, while a mutant from the Daudi cell line was selected for resistance to Verotoxin 1. Both were found to be deficient in globotriosylceramide with a corresponding increase in the precursor glycolipid lactosylceramide. Cell free assay of alpha-galactosyltransferase activity revealed that the Vero cell clone (VRP) contained significantly reduced enzyme activity, whereas in the case of the Daudi mutant (VT20), no significant decrease in activity was noted in vitro. These observations suggest a complex regulation of Gb3 biosynthesis which is considered in relation to P blood group antigen expression.

Animals↗
PubMed1991

Commercial levels of chymosin production by Aspergillus.

We have increased the production of bovine chymosin in Aspergillus niger var. awamori to more than one gram per liter of secreted authentic enzyme by combining a mutagenesis protocol with a novel robotic screening program. Analysis of the superior chymosin producing strains indicated that they have enhanced capabilities to secrete extracellular proteins.

Aspergillus niger↗
PubMed1991

Mapping of the epitopes of Epstein-Barr virus gp350 using monoclonal antibodies and recombinant proteins expressed in Escherichia coli defines three antigenic determinants.

The Epstein-Barr virus (EBV) major surface membrane antigen (MA), gp350/220, induces antibodies that neutralize virus infectivity in vitro. The MA glycoprotein is encoded by nucleotides 1784 to 4504 of the BamHI L fragment of the EBV genome. To define the antigenic epitopes on gp350, sequences encoding portions of the protein were cloned into an Escherichia coli expression system and eight recombinant clones were generated, two overlapping clones representing the C terminus and six overlapping clones representing the N terminus. The epitopes expressed by the recombinant proteins were mapped using 14 anti-MA monoclonal antibodies (MAbs) in a dot blot immunoassay. One of the MAbs reacted with clones that express the C terminus of gp350 and three others reacted with clones expressing the N terminal portion of the protein; the remaining MAbs tested were not reactive with the cloned proteins. The data identify three antigenic determinants on gp350. DNA sequences encoding these epitopes are located between nucleotides 1980 and 2307, 3186 and 3528, and 3528 and 3576 of the BamHI L fragment. In an attempt to elicit neutralizing antibodies, rabbits were immunized with gel-purified recombinant proteins from four of the clones. Neutralization assays indicate that the proteins expressed by these clones do not induce in vitro virus-neutralizing antibodies.

Animals↗
PubMed1991

An experimental model to assess the value of laser angioplasty in the management of atheromatous disease of the carotid bifurcation.

Laser angioplasty is used to vaporize atheroma in limb arteries. The present investigation was undertaken to determine the nature, size and quantity of particulate matter generated, and the appearance of the intima of a carotid artery model after laser treatment. Particulate matter was not significantly increased following treatment of 39 autopsy carotid bifurcations, but superficial plaques were vaporized and the surface of fibrous lesions glazed. It is anticipated that atheromatous carotid vessels would be rendered less thrombogenic and the risk of cerebral embolism reduced later angioplasty.

Aged↗
PubMed1989

Chemiluminescent assay of alkaline phosphatase applied in an ultrasensitive enzyme immunoassay of thyrotropin.

We compared a chemiluminescent assay and a colorimetric endpoint assay for measuring an alkaline phosphatase (EC 3.1.3.1) label in an enzyme immunoassay of thyrotropin (TSH). The substrate in the chemiluminescent assay is a derivative of adamantyl 1,2-dioxetane phosphate. On dephosphorylation, catalyzed by alkaline phosphatase, the 1,2-dioxetane decomposes further and emits a glow of light (lambda max 470 nm). We modified the Hybritech Tandem-E TSH High Sensitivity assay for chemiluminescent detection of bound alkaline phosphatase label by using this substrate (with 20-, 40-, and 60-min incubations). Detection limits (mean +2 SD of zero standard) were 6.0, 5.2, and 4.5 micro-int. units/L for these incubation periods, respectively, vs 20 micro-int. units/L for the conventional colorimetric version of the assay. Comparison of results for 44 clinical specimens assayed by the chemiluminescent (20-min incubation, y) and colorimetric (60-min endpoint, x) TSH immunoassays gave statistical values of: slope = 1.17, intercept = -0.22, and r = 0.98. Hemoglobin, but not bilirubin, lipids, or protein, interfered; but these interferents were removed by the washing steps in the enzyme immunoassay.

Alkaline Phosphatase↗
PubMed1988

Epstein-Barr virus in the bone marrow of patients with aplastic anemia.

STUDY OBJECTIVE: To determine whether Epstein-Barr virus is present in the bone marrow of patients with aplastic anemia. DESIGN: Assay of fresh and fixed bone marrow specimens for Epstein-Barr virus using immunofluorescence for nuclear antigen, Southern analysis with an Epstein-Barr virus specific probe, and in-situ hybridization. SETTING: Governmental medical referral center. PATIENTS: Five patients were studied prospectively: three who previously had infectious mononucleosis, one with a recent viral pneumonitis, and one who was asymptomatic. Stored DNA samples from other patients with aplastic anemia were also screened. MEASUREMENTS AND MAIN RESULTS: Epstein-Barr virus DNA and protein were detected in the bone marrow of 5 patients studied prospectively and in 1 of 40 patients studied retrospectively. As estimated by in-situ hybridization, about 3% to 5% of marrow cells were infected with virus in those patients who had not received acyclovir. In contrast, Epstein-Barr virus DNA was not detected in peripheral blood DNA of these patients, nor were Epstein-Barr virus proteins or DNA found in the bone marrow of normal donors, patients with other hematologic diseases, or in 1 patient with acute infectious mononucleosis. Analysis of DNA fragments by hybridization with Epstein-Barr virus probes showed a pattern dissimilar to the type of Epstein-Barr virus usually associated with infectious mononucleosis. CONCLUSIONS: Aplastic anemia may be associated with Epstein-Barr virus more commonly than suspected by history. Localization of the virus in the bone marrow supports a causative role for Epstein-Barr virus in bone marrow failure.

Adolescent↗
PubMed1988

Treatment of tumors of the thoracic and lumbar spinal column.

From December 1981 to February 1986, 33 patients with tumorous conditions of the spine were treated with anterior, posterior, or combined anterior and posterior surgical techniques. Breast metastases were by far the most common condition, accounting for more than 51% of patients with metastatic spinal disease. The surgeon treating tumorous conditions of the spine must be aware that, to date, the treatment is palliative only. The goals of the surgery and treatment are to reduce pain, preserve or improve neurologic function, and allow early mobilization. Survival overall averaged 9.1 months. Of the 14 patients who had anterior decompression alone, average survival time was 9.9 months. The 14 patients who had posterior procedures had an average survival time of 11.9 months. Five patients treated with combined anterior and posterior procedures survived 9.6 months. Fifteen patients with multiple-level spinal involvement survived 7.9 months, compared with 12.9 months for the 18 patients with single-level spinal involvement. Aggressive surgical treatment definitely improves the quality of life of patients with cord compression or unstable spinal segments secondary to bony destruction. An aggressive approach is indicated because it permits most patients to spend the remainder of their lives relatively pain-free and with intact spinal cord function.

Adult↗
PubMed1985

Myelopathy following intrathecal chemotherapy in a patient with extensive Burkitt's lymphoma and altered immune status.

A 30-year-old homosexual man presented with widespread Burkitt's lymphoma. On the basis of immunologic and viral studies, he was suspected of having the acquired immune deficiency syndrome. Following chemotherapy that included intrathecal cytosine arabinoside and methotrexate, brain stem edema, paraplegia, and an elevated cerebrospinal fluid level of myelin basic protein developed. Autopsy revealed vacuolar demyelination of spinal cord, brain stem, and cerebellum. The pathologic findings were similar to those reported to occur in myelopathy associated with intrathecal chemotherapy, but far more extensive. The contribution of the suspected acquired immune deficiency syndrome is unknown.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Herpesvirus saimiri-induced lymphoblastoid rabbit cell line: growth characteristics, virus persistence, and oncogenic properties.

A nonproducer lymphoblastoid cell line (7710) containing the herpesvirus saimiri (HVS) genome was established from the HVS-positive spleen of a male, inbred New Zealand White rabbit (III/J strain) which had developed a well-differentiated lymphoma after inoculation of HVS and 12-O-tetradecanoylphorbol-13-acetate (TPA). Antibodies to HVS early and late antigens were detected in the serum of rabbit 7710 by indirect immunofluorescence and immunoprecipitation. The cell line was of T-cell origin, did not produce HVS, and could not be superinfected with HVS. However, HVS early antigens could be induced in the cells with n-butyric acid and TPA or TPA alone. On the other hand, late antigens were never observed, and infectious virus could not be rescued by cocultivation of 7710 cell with OMK cells. The 7710 cells were T-cell growth factor dependent, even after many in vitro passages. The 7710 cell line contained multiple copies of a nonintegrated, covalently closed circular HVS genome. As is characteristic of some other HVS-transformed nonproducer lymphoid cell lines, a large segment of unique light (L) DNA was missing in the persistent circular viral DNA present in 7710 cells. This deletion spanned at least 42.5 kilobases, corresponding to the segment between 12.3 and 50.7 map units of full-length, infectious virion L-DNA. The 7710 cells failed to induce tumors in athymic nude mice, but inbred rabbits inoculated with as few as 100 of these cells developed fatal lymphomas. Chromosomal analysis showed that tumors were due to the growth of donor cells. Cells recovered from one of the rabbits inoculated with 7710 cells also contained HVS DNA and, after in vitro culture, induced the same type of lymphoma when inoculated into two other III/J-strain rabbits. None of the previously described HVS-transformed cell lines have been able to induce tumors in either their host species or nude mice. Thus, our demonstration that the 7710 cell line is readily transplantable in syngeneic rabbits represents the first available model which allows analysis of many biological and molecular aspects of the in vivo oncogenicity of HVS.

Animals↗
PubMed1985

Persisting illness and fatigue in adults with evidence of Epstein-Barr virus infection.

Clinical, serologic, virologic, and immunologic evaluations for 31 adults with chronic illness and fatigue suggested that 23 had persisting Epstein-Barr virus infection. Among these 23 patients, cellular immune mechanisms were generally normal, but 4 had mild immunoglobulin deficiencies. However, 20 patients had abnormal serologic profiles specific for Epstein-Barr virus shown by significantly elevated titers of antibodies to the viral capsid antigen or early antigen, or by a deficiency of late-appearing antibodies. In 11 of 15 patients tested, circulating immune complexes were found. Circulating interferon was not found in 18 patients tested, but the activity of 2-5 oligoadenylate synthetase, an interferon-induced enzyme, was increased in 5 patients studied. Of 19 patients, 18 had persisting suppressor T-cell activity typically found in patients recovering from acute infectious mononucleosis. We believe that the Epstein-Barr virus may be associated with chronic illness in adults.

Adolescent↗
PubMed1985

Transfer of reactivity with in vitro produced transfer factor in rhesus and owl monkeys.

Transfer factors against two heterologous antigens, Herpesvirus saimiri and owl monkey kidney cells, were replicated in vitro in a human lymphoblastoid cell line (LDV/7) and injected into rhesus and owl monkeys. Transfer of immunity was demonstrated by the leukocyte migration inhibition assay. This study suggests that heterologous transfer factor, replicated in vitro, can transfer cellular immunity against membrane antigens in rhesus and owl monkeys.

Animals↗
PubMed1984

Herpesvirus infections in the acquired immune deficiency syndrome.

Herpesvirus infections were studied in persons with or at risk for the acquired immune deficiency syndrome (AIDS). The infections diagnosed were as follows: patients with AIDS, cytomegalovirus (CMV) in 34 of 34, Epstein-Barr virus (EBV) in 33 of 34, herpes simplex viruses (HSV) in eight of 34, and varicella zoster virus in four of 34; patients with chronic lymphadenopathy syndrome, CMV in eight of nine and EBV in nine of nine; in healthy homosexual men, CMV in five of 13 and EBV in seven of eight. Cytomegalovirus infections were frequently related to disease and death. Herpesvirus infections are frequent causes of serious diseases in AIDS. The prevalence of EBV and CMV infections in AIDS and the chronic lymphadenopathy syndrome may be the result of an important interaction between these viruses and the cause of AIDS.

Acquired Immunodeficiency Syndrome↗