Measles virus hemagglutinin protein expressed in transgenic lettuce induces neutralising antibodies in mice following mucosal vaccination.

Plant-made oral vaccines have the potential to overcome many of the limitations of traditional vaccines. Here we report on progress towards a lettuce-made measles vaccine. Lettuce is a palatable species which exhibits rapid growth in contained hydroponic systems and produces negligible quantities of toxins. Measles virus hemagglutinin (MV-H) protein was successfully expressed in transgenic lettuce and found to be immunogenic in mice. Lettuce extracts containing MV-H protein induced MV neutralising antibodies following intraperitoneal injection and intranasal inoculation of mice. Using a sequential prime-boost strategy in which mice were vaccinated with MV-H DNA followed by an orally delivered freeze-dried MV-H lettuce formulation a 10-fold increased in MV-specific IgG titers was observed relative to mice vaccinated with control lettuce formulations (p=0.05). MV-H protein was stable in freeze-dried lettuce for up to 13 months at room temperature, and survived at least a week at temperatures as high as 50 degrees C. This research represents a significant step towards the development of measles vaccine formulation that is effective, temperature-stable, easy to administer in a resource-poor setting and amenable to large scale manufacture.

Crude saponins improve the immune response to an oral plant-made measles vaccine.

Millions of people live in areas where infectious diseases, such as measles, are endemic and resources are scarce. Heat-stable vaccines that are delivered orally will greatly enhance vaccination programs in these areas. A stumbling block in the development of oral vaccines is the availability of safe and effective mucosal adjuvants, especially for use with subunit vaccines. The experiments presented here examine the ability of CTB/CT, LT(R192G) and crude Quillaja saponin extracts to stimulate MV-specific immune responses in mice, following oral immunisation with plant-made measles virus hemagglutinin (MV-H) protein. LT(R192G) and crude saponin extracts both functioned as potent mucosal adjuvants when ad-mixed with plant-made MV-H protein, and were more effective than CTB/CT. MV-H protein supplemented with saponin extract induced the strongest MV-specific responses, in the greatest number of mice. Crude saponins are routinely used by the food and beverage industry at concentrations greater than those required for adjuvanticity, and as such, they have a better safety profile than bacterial enterotoxins. This study demonstrates their potential as adjuvants for use with oral plant-made vaccines.

Educating future physicians for Ontario.

In 1987, Ontario's physicians conducted a strike, ultimately not successful, over the issue of "extra billing." The fact that the Ontario public did not support this action reflected a major gap between the profession's view of itself and the public's view of the profession. In 1990, the province's five medical schools launched a collaborative project to determine more specifically what the people of Ontario expect of their physicians, and how the programs that prepare future physicians should be changed in response. The authors report on the first five years of that ongoing project. Consumer groups were asked to state their views concerning the current roles of physicians, future trends that would affect these roles, changes in roles they wished to see, and suggestions for changes in medical education. Methods used included focus groups, key informant interviews, an extensive literature review, and surveys, including a survey of health professionals. Concurrently, inter-university working groups prepared tools and strategies for strengthening faculty development, assessing student performance, and preparing future leadership for Ontario's medical education system. Eight specific physician roles were identified: medical expert, communicator, collaborator, health advocate, learner, manager ("gatekeeper"), scholar, and "physician as person." Educational strategies to help medical students learn to assume these eight roles were then incorporated into the curricula of the five participating medical schools. The authors conclude that the project shows that it is feasible to learn specifically what society expects of its physicians, to integrate this knowledge into the process of medical education reform, and to implement major curriculum changes through a collaborative, multi-institutional consortium within a single geopolitical jurisdiction.

Demand-side medical education: educating future physicians for Ontario.

Initiated by Associated Medical Services (AMS), Educating Future Physicians for Ontario is a 5-year collaborative project whose overall goal is to make medical education in Ontario more responsive to that province's evolving health needs. It is supported by AMS, the five universities with medical schools or academic health sciences centres and the Ontario Ministry of Health. The project's five objectives are to (a) define the health needs and expectations of the public as they relate to the training of physicians, (b) prepare the educators of future physicians, (c) assess medical students' competencies, (d) support related curricular innovations and (e) develop ongoing leadership in medical education. There are several distinctive features: a focus on "demand-side" considerations in the design of curricula, collaboration within a geopolitical jurisdiction (Ontario), implementation rather than recommendation, a systematic project-evaluation plan and agreement as to defined project outcomes, in particular the development of institutional mechanisms of curriculum renewal as health needs and expectations evolve.

Setting educational priorities for learning the concepts of population health.

Following the World Health Organization's policy of 'Health for All by the Year 2000', doctors are increasingly being seen as health care providers to populations of patients, in addition to their more traditional role as doctors to individuals in a one-to-one encounter. In order for doctors to take on this expanded role, they must learn the knowledge and skills appropriate to population health. In this paper, we propose a method of educational priority-setting which allows educational planners to identify those diseases and adverse health conditions most appropriate for studying the concepts of population health. Using the Measurement Iterative Loop of Tugwell and colleagues as a framework, a table of Priority Illness Conditions was developed and compared with a previous priority list developed from a survey of clinical teachers at the McMaster University Medical School. Discussion of the implications for this approach in setting educational priorities at undergraduate, postgraduate and continuing medical education levels is presented, along with a review of possible shortcomings and caveats in using this approach.

Effect of prostaglandins on complement production by tissue macrophages.

Tissue macrophages produce several proteins of the complement system. The mechanisms that regulate this process are poorly understood. The established ability of certain prostaglandins to influence macrophage secretory activity suggests that these lipid mediators may also modulate complement production (CP). Using the guinea pig peritoneal macrophages, we determined the effects of selected prostaglandins on in vitro CP and found that PGE2 inhibited production of complement proteins but not lysozyme; the response of elicited and resident peritoneal cells to PGE2 was identical; and PGE1, PGF2 alpha, and PGI2 had no detectable effect. PGE2 may contribute to regulation of CP in vivo.

Arachidonic acid-mediated and serum-opsonized-zymosan-mediated inhibition of complement production by macrophages. Lack of requirement for endogenous arachidonic acid metabolites.

The ability of exogenous prostaglandins to inhibit complement production (CP) by monocytes and macrophages (M phi) suggests that endogenous arachidonic acid metabolites produced by these cells may also regulate their rate of CP. We assessed the regulatory influence of endogenous metabolites on CP by M phi utilizing exogenous arachidonic acid and serum-opsonized zymosan as stimulators of production of cyclooxygenase and lipoxygenase metabolites. The results of this study show that (i) the inhibition of CP caused by both agents is is independent of arachidonic acid metabolites, suggesting that endogenously produced metabolites do not influence CP, and (ii) arachidonic acid and serum-opsonized zymosan inhibit production by independent mechanisms.

C5a and antigen-induced tracheal contraction: effect of a combination of an antihistamine and cyclo-oxygenase inhibitors.

Our previous studies with C5a, a cleavage product of the fifth component of complement, have shown that the antihistamine diphenhydramine and the cyclo-oxygenase inhibitor aspirin do not inhibit the C5a-induced contraction of isolated guinea pig trachea (Regal, Eastman & Pickering, 1980; Regal & Pickering, 1981). We investigated the effect of cyclo-oxygenase inhibitors in the presence of diphenhydramine to determine if cyclo-oxygenase products were contributing to the contraction beyond any effect they might have on histamine release. A combination of a cyclo-oxygenase inhibitor and diphenhydramine caused a delay in onset and decrease in magnitude and duration of the C5a-induced contraction. Indomethacin itself also caused a slight inhibition. In contrast, a combination of aspirin and diphenhydramine did not inhibit the initial portion of antigen-induced tracheal contraction any more than diphenhydramine alone and enhanced the later portion just as aspirin alone. Cross tachyphylaxis experiments demonstrated that antigen pretreatment significantly inhibited a subsequent C5a-induced tracheal contraction, though C5a pretreatment did not affect a subsequent antigen-induced contraction. Thus, cyclo-oxygenase products do contribute to C5a-induced tracheal contraction, and histamine participation in the presence of cyclo-oxygenase inhibitors is suggested. Our studies demonstrate the dissimilarities of C5a and antigen-induced contraction as regards inhibition by aspirin plus diphenhydramine, yet suggest common pathways leading to the contractile response as evidenced by cross tachyphylaxis experiments.

Enhancement of granulocyte oxidative metabolism in sera from patients with C2 deficiency and systemic lupus erythematosus.

Serum or plasma from 3 patients with C2 deficiency (C2D) and systemic lupus erythematosus (SLE) significantly enhanced chemiluminescence and superoxide anion production by polymorphonuclear leukocytes (PMN) after stimulation with phorbol myristate acetate or latex beads. PMN from patients and normal individuals were supranormally activated when resuspended in plasma from these patients. No such effect was seen with plasma from a patient with C2D but with no evidence of SLE, from patients with SLE but not C2D, from patients with C1q or C8 deficiency, from C4-deficient guinea pigs, or NZB-NZW mice. Because oxygen-derived free radicals may cause joint or tissue damage, C2D patients who have or develop this activity in their plasma may be more prone to SLE or other collagen-vascular diseases.

Deficiency of the second complement component association with the HLA haplotype A10, B18 in a normal population.

Serum C2 activity was measured in 135 individuals drawn from a panel of 418 tissue-typed blood donors. The study group included all donors with HLA antigens A10 and B18. Heterozygote C2 deficiency (C2Dhet) was defined by reference to the range of C2 activity in previously studied obligate heterozygotes. Five donors were C2Dhet. Family studies confirmed that C2Dhet was associated in all instance with an A10, B18 haplotype. The minimum frequency for C2Dhet was 1.2% in the panel of 418 donors and 62.5% in those donors with an A10, B18 haplotype.

Phagocytosis, chemoluminescence, and intracellular killing of fungi by phagocytes from subjects with deficiency of the second component of complement.

The capacity of phagocytes from animals or humans with complement component deficiency to ingest and kill Candida albicans has been much disputed. We show that peripheral blood polymorphonuclear leukocytes and mononuclear phagocytes from subjects with hereditary C2 deficiency (C2D) ingested C. albicans or Saccharomyces cerevisiae at an abnormally slow rate. After preincubating C. albicans in C2D plasma, the slow rate of phagocytosis was corrected and subsequent intracellular killing of C. Albicans was normal. A normal number of C2D phagocytes reduced nitroblue tetrazolium after stimulation with either phorbol myristate acetate or ingestion of C. albicans. The rate at which chemoluminescence was generated in response to C. albicans was abnormally slow, but peak chemoluminescence produced by C2D phagocytes in response to C. albicans was normal.

C5a-induced tracheal contraction: effect of an SRS-A antagonist and inhibitors of arachidonate metabolism.

C5a, a peptide derived from the fifth component of complement, has been shown to cause significant prolonged smooth muscle contraction in isolated guinea pig trachea. This contraction was not affected by the antihistamine diphenyhydramine. To assess further the potential role that C5a may play in allergic bronchospasm, we investigated the role of products of arachidonate metabolism in the C5a-induced tracheal contraction. 5,8,11,14-Eicosatetraynoic acid, an inhibitor of lipoxygenase and cyclooxygenase, virtually eliminated the tracheal contraction induced by C5a. The prostaglandin synthesis inhibitor, acetylsalicylate, did not inhibit the C5a-induced tracheal contraction and enhanced the tracheal response to acetylcholine. FPL 55712, an antagonist of slow reacting substance of anaphylaxis (SRS-A), almost completely inhibited the tracheal response to C5a and at higher concentrations employed, FPL 55712 also inhibited the tracheal response to exogenous prostaglandin F 2 alpha. These studies indicate that C5a-induced tracheal contraction is mediated by a product or products of arachidonate metabolism, and is, at least in part, mediated by SRS-A.

C5a induced tracheal contraction: a histamine independent mechanism.

C5a, a peptide derived from the fifth component of complement, caused significant prolonged smooth muscle contraction in isolated guinea pig trachea. Diphenhydramine, a histamine receptor antagonist of the H1 type, had no effect on either the rate, amplitude or duration of C5a induced tracheal contraction, whereas it significantly inhibited the tracheal response to exogenous histamine. Diphenhydramine also caused a significant delay in the response to compound 48/80 in normal guinea pig trachea and to antigen in actively sensitized trachea, indicating that the antihistamine was capable of inhibiting tracheal contractions to endogenously released histamine. C5a induced tracheal smooth muscle contraction was also unaffected by antagonists of H2, muscarinic cholinergic and alpha adrenergic receptors. These results indicate that C5a induced tracheal contraction is independent of histamine and is potentially a mediator of allergic bronchospasm.

Regional deficiency of secretory IgA in a patient with combined immunodeficiency of the ADA deficient type.

The IgA system in a patient with SCID and ADA deficiency showed heterogeneity. Serum IgA and stool secretory IgA (SIgA) levels were normal, but with altered kappa/lambda and A1/A2 subclass ratios; IgA in saliva and urine was deficient. Amounts of secretory component were normal. Jejunal and rectal biopsies showed prominent lymphonodular hyperplasia, but no cells containing IgA. A normal serum IgA level therefore does not always predict an intact secretory IgA system.

Abnormalities of the complement system in Reye syndrome.

Sixteen patients with Reye syndrome had diminished concentration of serum complement proteins and/or hemolytic activity in the earliest blood sample. All 12 studied with hemolytic methods had significantly reduced C1 activity; total hemolytic complement activity was reduced in only three. Low Cl activity was accompanied by equivalent reduction of Cls in 11 of 12 patients; Clq was less than normal in only two of 12. Decreased levels of at least one other classical pathway complement hemolytic activity or protein concentration were found in 13 patients, whereas factor B or the alternate complement pathway was normal or elevated in the ten patients studied. The consistent reduction of Cls protein concentration in Reye syndrome suggests that early metabolic abnormalities regularly affect the production or catabolism of this protein. Although normal serum Clq concentration in the majority of these patients does not support an immune pathogenesis, decreased Clq, C4, and C2 in three patients does suggest that immune mechanisms may be responsible for the serum complement abnormalities in this latter group of patients.

Heterogeneity of the clinical syndrome in patients with systemic lupus erythematosus and genetic deficiency of the second complement component.

Two patients with systemic lupus erythematosus associated with homozygous deficiency of the second complement component (SLE-C2D) illustrate the different clinical disease patterns found in patients with this illness. Despite the differences in extent and severity of clinical manifestations and serological findings, the renal disease was similar and kidney function was well preserved in both patients. Renal microscopic changes were focal and segmental, deposits of immuno-globulins and complement components were present by immunofluorescent staining, and dense deposits were seen by electron microscopy. Tubulo-reticular inclusion bodies were found in glomerular endothelial cells and lymphocytes of both patients, but not in the lymphocytes of a clinically healthy C2D sibling. The findings in these two patients stress the importance of careful evaluation to determine the presence of systemic disease in patients with SLE-C2D and suggest that an intact classic complement pathway is important in the development of severe lupus, nephritis, but is not needed in the pathogenesis of lupus skin lesions.