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Biomedical subjects

L A Page

Publications and source records attributed to L A Page.

At least 19 recordsLinked to original sources
PubMed1996

An anti-cytokine bioactivity assay for interferons-alpha, -beta and -omega.

Interferons-alpha and -beta (IFN-alpha and -beta) are cytokines that are widely known to induce potent anti-viral activity. However, it has become increasingly apparent that IFN-alpha and -beta exert a variety of other biological effects, including anti-tumour and immunomodulatory activities and are increasingly used clinically to treat a range of malignancies, myelodysplasias and autoimmune diseases, e.g., IFN-beta for multiple sclerosis. The most widely used bioassays for the IFNs are based on their anti-viral activity, but these do not predict the biological activity of the IFNs in anti-tumour and immunomodulatory therapies. Thus, we have developed anti-cytokine-based bioassays that may be more reflective of such activity and which have several advantages over existing anti-viral bioassays. The anti-cytokine bioassay is based on the ability of IFN-alpha, -beta and -omega to inhibit granulocyte-macrophage-colony-stimulating factor (GM-CSF) induced proliferation of the erythroleukaemic cell line TF-1. This assay can take only 24 h, is sensitive to 200 fg (0.04 IU) IFN-alpha or -beta and 100 fg (0.02 IU) IFN-omega and is able to detect down to these levels in serum or plasma samples. The usefulness of anti-cytokine bioassays for IFN-alpha, -beta and -omega is not restricted to the GM-CSF/TF-1 cell format and other alternatives are available, such as erythropoietin (EPO)/TF-1 cells and EPO/UT-7-EPO cells. These assays can be made specific for each of the IFNs by including neutralising antibodies in the bioassay.

Humans↗
PubMed1996

An antiproliferative bioassay for interleukin-4.

Interleukin-4 (IL-4) is currently being used for therapeutic intervention in a wide range of malignant diseases as an antitumour agent. Although bioassays have been developed that measure the proliferative capacity of IL-4, none measure the antiproliferative activity of this molecule. We have developed a simple, sensitive bioassay for human IL-4 based on the ability of this cytokine to inhibit the proliferation of the human lung carcinoma line, CCL-185, an easy to maintain, cytokine independent, cell line. It is rapid, reproducible and sensitive, able to detect 2 pg/ml IL-4. The assay is completely unresponsive to all other interleukins from IL-2 to IL-12, to the colony stimulating factors and transforming growth factor beta and is 100-fold less sensitive to interferon-alpha, tumour necrosis factor-alpha, IL-1 beta and IL-13. The assay can be made completely specific for IL-4 by including specific neutralizing antibodies for IL-4 and is suitable for the estimation of IL-4 in both plasma and serum samples.

Biological Assay↗
PubMed1996

A sensitive human cell line based bioassay for megakaryocyte growth and development factor or thrombopoietin.

We have developed a simple, rapid, sensitive bioassay for megakaryocyte growth and development factor (MGDF) or thrombopoietin (TPO) based on its ability to stimulate the proliferation of the human megakaryoblastic cell line MO7e. The bioassay takes only 24 h, is reproducible and sensitive to less than 10 pg/ml of MGDF. It can be made specific for MGDF by including neutralizing antibodies specific for MGDF, and is suitable for detection of MGDF in both plasma and serum samples.

Antibodies↗
PubMed1995

Evidence for a signaling role for the alpha chains of granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5 receptors: divergent signaling pathways between GM-CSF/IL-3 and IL-5.

In the present study, we have used a human erythroleukemia cell line, TF-1, that proliferates in response to granulocyte macrophage colony stimulating factor (GM-CSF), interleukin-3 (IL-3), and interleukin-5 (IL-5) to investigate the role of receptors for these cytokines in signal transduction mechanisms involved in proliferative responses. The receptors for GM-CSF, IL-3, and IL-5 each possess a cytokine specific alpha subunit, but all three share a common beta chain. Using an immunoblotting system designed to detect phosphotyrosine containing proteins and a permeabilized cell system to detect rapid changes in phosphate turnover on proteins, we show that while GM-CSF and IL-3 use tyrosine phosphorylation to mediate mitogenic signal transduction, IL-5 uses tyrosine dephosphorylation in its signaling pathway. The use of different signaling pathways by these cytokines can be confirmed in a biologic system whereby the proliferation induced in culture by GM-CSF and IL-3 is inhibited by tyrosine kinase inhibitors, but that induced by IL-5 is enhanced. Conversely, GM-CSF- and IL-3-induced proliferation is stimulated by a tyrosine phosphatase inhibitor, yet IL-5-induced proliferation is inhibited. Inhibitors of protein kinase C inhibit IL-3- and GM-CSF-, but not IL-5-induced proliferation. We suggest that, because all these cytokines share the identical beta chain of their receptors, the cytokine specific alpha chain mediates the linkage of each receptor to the individual biochemical signal transduction pathways responsible for the different biologic activities of these cytokines.

Alkaloids↗
PubMed1995

Activated phenotype in neutrophils and monocytes from patients with primary proliferative polycythaemia.

AIM: To investigate whether monocytes and neutrophils from patients with primary proliferative polycythaemia (PPP) exhibit increased expression of markers of cell activation and, if so, whether they are associated with the phagocytic activity of these cells and concentrations of circulating cytokines. METHODS: Expression of CD11b, CD14, CD18, and CD64 on monocytes and neutrophils was assessed by flow cytometry. Phagocytosis was analysed using immunoglobulin opsonised Escherichia coli. Serum concentrations of granulocyte colony stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF) and macrophage CSF (M-CSF) were determined by bioassays, and interferon-gamma (IFN-gamma) by enzyme linked immunosorbent assay (ELISA). RESULTS: Patients with PPP (n = 18), when compared with normal subjects (n = 10), had increased percentages of CD64+ monocytes (52% v 36%) and neutrophils (42% v 11%) and of CD14+ neutrophils (36% v 18%). Monocytes from patients with PPP exhibited increased expression of CD64 (47 v 26) and of CD11b (65 v 36). These abnormalities were not found in patients with secondary (n = 8) or apparent (n = 13) polycythaemia. The percentage of neutrophils undergoing phagocytosis was higher in patients with PPP (mean 64%; n = 6) than in normal subjects (mean 42%; n = 5). G-CSF, GM-CSF and IFN-gamma concentrations in patients' serum samples were comparable with normal; M-CSF was not detected in any of the samples. There was no correlation between cytokine concentrations and the expression of CD11b, CD14, CD18, and CD64 on patients' phagocytes. CONCLUSIONS: Increased expression of CD11b and CD64 by monocytes, increased percentages of CD14+ and CD64+ neutrophils and the high phagocytic activity of neutrophils suggests that these cells are activated in vivo in patients with PPP. The phenotypic changes of PPP phagocytes were not associated with increased concentrations of circulating cytokines and probably reflect intrinsic abnormalities within the neoplastic PPP clone.

Antigens, CD↗
PubMed1990

Hypothalamic-pituitary-ovarian function in menstruating women with Turner syndrome (45,X).

The hypothalamic-pituitary-ovarian hormone secretion patterns were evaluated in two women with 45,X Turner syndrome, spontaneous sexual development, and monthly menstrual periods. Each women had serum gonadotropin and sex steroid determinations during two or more menstrual cycles. During the follicular phase of a menstrual cycle, both women received 100 micrograms gonadotropin-releasing hormone (GnRH) s.c., and serum LH and FSH responses were determined. In addition, one woman collected daily overnight urine specimens for 40 consecutive days, spanning two menstrual periods, for the measurement of LH, FSH, estriol, and free progesterone. The randomly measured hormone results showed low serum progesterone concentrations during luteal phases, consistent with the interpretation of anovulation or inadequate corpus luteum function. At the time of the GnRH stimulation tests, baseline serum FSH concentrations and FSH responses to GnRH were within normal limits, whereas baseline LH levels and LH responses to GnRH were low. The pituitary gonadotropin secretion patterns were more consistent with patterns seen during early puberty than in the perimenopausal state. This interpretation was further confirmed by the urinary excretion patterns of gonadotropins, which were not significantly elevated. Furthermore, the urinary hormone profiles revealed that, although the intermenstrual period was of normal length, the follicular phase was prolonged, with normal levels of LH, FSH, and estriol excreted. The menstrual cycle studied was ovulatory but had a short luteal phase. The hormone results indicated that the dysgenetic ovary of women with 45,X Turner syndrome is capable of producing sufficient quantities of sex steroids and other regulatory factors to maintain gonadotropin secretion patterns that are reminiscent of early puberty.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1979

Inheritance of uncomplicated hypospadias.

Isolated first-degree hypospadias in three generations of one family and in two generations of two families is reported and the literature reviewed. Pedigree information suggests autosomal-dominant, sex-limited inheritance in these cases although other inheritance patterns are possible. Mendelian transmission of hypospadias may be more frequent than commonly believed and implies that the abnormality is potentially definable in molecular terms.

Female↗
PubMed1979

Direct immunofluorescence tests with counterstains for detection of Chlamydia psittaci in infected avian tissues.

Different methods of preparation and serological evaluation of rabbit globulins for use in fluorescent antibody conjugate and different methods of counterstaining with fluorescent antibody tests were evaluated for detection of Chlamydia psittaci in infected turkey tissues. The agar gel precipitin reaction was that chosen for testing and selecting antiserums to be used for fluorescein isothiocyanate conjugation. The fluorescent antibody staining was most pronounced with conjugate made from globulins precipitated with ammonium sulfate. A direct fluorescent antibody method with Evans blue counterstain correctly identified "coded" specimens of C. psittaci-infected and noninfected turkey air sacs. However, naphthalene black was superior to Evans blue as a counterstain when infected pericardial sacs were tested.

Animals↗
PubMed1978

Legionnaires' disease: antigenic peculiarities, strain differences, and antibiotic sensitivities of the agent.

Paired sera from victims of Legionnaires' disease showed, in many cases, significant rises in immunoglobulin G antibodies to both the causative agent (LA) of Legionnaires' disease and Chlamydia psittaci, but concurrent rises in immunoglobulin M antibodies only against LA. Guinea pigs experimentally infected with LA likewise responded with antibodies to both C. psittaci and LA. Guinea pigs infected with LA also reflected significant differences in antigenic makeup and in pathogenicity among four strains of LA examined. In antibiotic studies, rifampin was 200 times more effective than erythromycin and 17,000 times more effective than tetracycline in plaque reduction tests of LA in monolayer cultures of primary chick embryo cells. An isolate of LA recovered from a healthy person was compared with three isolates from persons with fatal infections.

Animals↗
PubMed1976

Observations on the involvement of wildlife in an epornitic of chlamydiosis in domestic turkeys.

In an investigation of potential wildlife reservoirs of Chlamydia psittaci at the site of an acute, highly fatal epornitic of chlamydiosis in domestic turkeys in Texas, various species of wild birds and rodents were captured and tested for chlamydial serum antibodies and chlamydiae in their tissues. Thirteen (65%) of 20 blackbirds (Agelaius sp), 4 (44%) of 9 killdeer (Oxyechus vociferus), 3 (27%) of 11 sparrows (Passer sp) and 1 of 4 mourning doves (Zenaidura macroura) were seropositive, but chlamydiae were not isolated from their tissues. Two of 3 rats (2 cotton rats, Sigmodon hispidus, and 1 roof cat, Rattus rattus) were seropositive, but 7 gophers (Citellus sp), 1 ground squirrel (Tamias sp), an opossum (Didelphis virginiana), and a domestic cat (Felis domesticus) were seronegative; however, chlamydiae were recovered from the livers and spleens of the opossum and domestic cat, both of which had been observed scavenging carcasses of turkeys dead of chlamydiosis. Cultures of these isolants were inoculated experimentally into turkeys and produced lesions of chlamydiosis that were indistinguishable from those caused by the strain originally recovered from diseases turkeys on the premises. Nine of 50 domestic goats quartered near the diseased turkeys were tested, and all were seropositive.

Animals↗
PubMed1975

An epornitic of fatal chlamydiosis (ornithosis) in South Carolina turkeys.

An unusual epornitic of fatal chlamydiosis occurred in a flock of 10,283 domestic turkeys in South Carolina. Total mortality over a 2-week period was 483 birds (4.7% of the flock). The principal gross lesion was severe pericarditis, but there was little or no airsacculitis, an observation at variance with many previous reports of chlamydiosis. Furthermore, an unusually heavy infestation of the turkeys with sanguivorous black flies (Simulium slossonae and S congareenarum) was observed at the time of the epornitic, an occurrence that may have permitted rapid transmission of chlamydiae between turkeys in the affected flock. The strains of Chlamydia psittaci isolated from naturally infected turkeys caused pericarditis and heptopathy as well as occasional airsacculitis, with a 41% mortality in intravenously (IV) inoculated turkeys. Turkeys inoculated intramuscularly (IM) or intraperitoneally (IP) did not die; however, airsacculitis was observed in more than 85% of turkeys inoculated intraperitoneally or exposed to infection by pen contact with inoculated turkeys. The strain was highly infectious but not lethal by the latter method of transmission. The strain was similar to other virulent chlamydiae isolated from turkeys, in that small numbers of the organism caused fatal infection in guinea pigs when inoculated IP.

Air Sacs↗