Parker A. Small

Electrophoretic Heterogeneity of Polypeptide Chains of Specific Antibodies

Heavy and light polypeptide chains isolated from different specific antibodies to haptens and from γG-immunoglobulin of normal rabbits have been resolved into distinct, multiple components by disc electrophoresis in polyacrylamide gels in the presence of urea. In spite of the resolution of these chains into multiple bands, different specific antibodies and normal rabbit γG-immunoglobulin were indistinguishable from each other by this method.

Role of IgA versus IgG in the Control of Influenza Viral Infection in the Murine Respiratory Tract

The roles of IgG and secretory IgA in the protection of the respiratory tract (RT) against influenza infection remain unclear. Passive immunization with Ab doses resulting in serum IgG anti-influenza virus Ab titers far in excess of those observed in immune mice has compounded the problem. We compared the effects of i.v. anti-influenza virus IgG and i.v. anti-influenza virus polymeric IgA (pIgA) mAb administered in amounts designed to replicate murine convalescent serum or nasal Ab titers, respectively. A serum anti-influenza virus IgG titer 2.5 times the normal convalescent serum anti-influenza virus IgG titer was required for detectible Ab transudation into nasal secretions, and a serum IgG titer 7 times normal was needed to lower nasal viral shedding by 98%. Anti-influenza virus pIgA at a nasal Ab titer comparable to that seen in convalescent mice eliminated nasal viral shedding. The RT of influenza-infected pIgA- or IgG-protected mice were studied by scanning electron microscopy. Only pIgA was found to prevent virally induced pathology in the upper RT, suggesting that IgG did not prevent viral infection of the nose, but neutralized newly replicated virus after infection had been initiated. In contrast, IgG, but not pIgA, was found to prevent viral pathology in the murine lung. Our results help to resolve the controversy of IgA- vs IgG-mediated protection of the RT; both Abs are important, with plasma IgG Ab serving as the back-up for secretory IgA-mediated protection in the nasal compartment, and IgG being the dominant Ab in protection of the lung.

Virus infection as a stressor: Influenza virus elevates plasma concentrations of corticosterone, and brain concentrations of MHPG and tryptophan

Balb/c mice were infected with influenza virus PR8 (H1N1) by the intranasal route. At various subsequent times, brain samples were examined for their content of catecholamine and indoleamine metabolites, and plasma corticosterone was measured. Virus infection was associated with a progressive loss of body and thymus weights, and an increase in plasma corticosterone. Spleen weight initially increased then decreased. There were also increases in the cerebral content of free tryptophan throughout the brain, and of MHPG, a major catabolite of norepinephrine, especially prominent in the hypothalamus. Thus influenza virus can be regarded as a stressor because, like behavioral stressors, it activates the hypothalamic-pituitary-adrenal axis, and increases cerebral concentrations of tryptophan and norepinephrine catabolites. These changes resemble those observed following administration of sheep red blood cells and Newcastle disease virus, noninfectious activators of the immune system, suggesting that noradrenergic and HPA activation are common concomitants of antigenic stimulation. The mediator of these effects may be interleukin-1 released by activated macrophages. It should be noted that animals infected with viruses can be expected to exhibit stress-like endocrine and neurochemical changes.

The electrophoretic homogeneity of the myosin subunits

Abstract Gel electrophoresis of myosin in concentrated urea solutions demonstrates that the dissociated chains of myosin migrate as a monodisperse electrochemical species. At lower urea concentrations a complex dissociation-association system is obtained. Sedimentation, viscosity, optical rotation and gel electrophoresis studies under the latter conditions indicate the equilibrium nature of the system.

Polypeptide Chains of Rabbit Gamma Globulin

Rabbit gamma globulin has been extensively reduced, and its polypeptide chains separated by gel filtration on Sephadex G-200 in SM guanidine hydrochloride. The larger H (or A) chains make up two-thirds of the molecule and have a molecular weight of approximately 55,000 each. The smaller L (or B) chains account for the other one-third and have a molecular weight of approximately 25,000 each. The data are consistent with a model of the gamma globulin molecule that has two H and two L chains.

Issues in medical education: basic problems and potential solutions.

No abstract available.

Peptide maps of rabbit γG-immunoglobulin heavy chains controlled by Allelic Genes

Peptide maps of the heavy polypeptide chains derived from rabbits of different genotype have shown practically identical fingerprints. Nevertheless, the heavy polypeptide chains with the a2 allotypic specificity could be distinguished from those with the al or a3 allotypic specificity by the presence of a yellow spot and the absence of a brown spot. The distinguishing yellow and brown spots were absent from the corresponding Fc-fragments. Moreover, the peptide maps of the Fc-fragments did not distinguish among the three allelic forms of heavy chains. Compared with the peptide maps of the Fc-fragments, only a few additional spots were present in the intact heavy chain. These few spots were insufficient to account for the Fd-fragment, implying that a significant portion of the Fd-fragment is too heterogeneous to be examined by the fingerprint method. The heavy polypeptide chains were found to be electropboretically heterogeneous and this heterogeneity was unrelated to genotype.

Peer nomination: a tool for identifying medical student exemplars in clinical competence and caring, evaluated at three medical schools.

Purpose Peer evaluation is underused in medical education. The goals of this study were to validate in a multiinstitutional study a peer nomination form that identifies outstanding students in clinical competency and interpersonal skills, to test the hypothesis that with additional survey items humanism could be identified as a separate factor, and to find the simplest method of analysis. Method In 2003, a 12-item peer nomination form was administered to junior or senior medical students at three institutions. Factor analysis was used to identify major latent variables and the items related to those characteristics. On the basis of those results, in 2004 a simpler, six-item form was developed and administered. Student rankings based on factor analysis and nomination counts were compared. Results Factor analysis of peer nomination data from both surveys identified three factors: clinical competence, caring, and community service. New survey items designed to address humanism are all weighted with interpersonal skills items; thus, the second major factor is characterized as caring. Rankings based on peer nomination results analyzed by either factor analysis or simply counting nominations distinguish at least the top 15% of students for each characteristic. Conclusions Counting peer nominations using a simple, six-item form identifies medical student exemplars for three characteristics: clinical competence, caring, and community service. Factor analysis of peer nomination data did not identify humanism as a separate factor. Peer nomination rankings provide medical schools with a reliable tool to identify exemplars for recognition in medical student performance evaluations and selection for honors (e.g., Gold Humanism Honor Society).

Influenza immunization: intranasal live vaccinia recombinant contrasted with parenteral inactivated vaccine

To compare the efficacy and duration of the immune response to local and systemic vaccination, Balb/c mice were vaccinated either intraperitoneally (i.p.) with an inactivated A/PR/8/34 (H1N1) vaccine or intranasally (i.n.) with a vaccinia recombinant containing the H1 gene of influenza. The i.p. inactivated vaccine stimulated high serum IgG anti-influenza titres and protected the lungs against viral challenge for the duration of the experiment (17 months). Little nasal wash IgA was induced and the noses were susceptible to challenge. Animals vaccinated i.n. with the recombinant had lower serum IgG titres and the lungs showed poor protection against challenge. Nasal wash IgA titres were higher, however, and the noses were largely protected from viral challenge for 17 months.

Interleukin 12 administration enhances Th1 activity but delays recovery from influenza A virus infection in mice

Interleukin 12 (IL-12) directs the differentiation of undifferentiated T helper (Th0) cells to T helper type 1 (Th1) cells and induces a cell-mediated immune response. To evaluate the effect of IL-12 on the course of influenza A virus infection, BALB/c mice were administered a daily intraperitoneal dose of 1000 ng of IL-12 or saline on days -1 to +4 for a total of six treatments. The treatment generally enhanced Th1-mediated responses. IFNgamma lung concentrations were 1193 +/- 275 pg/100 microl in controls and 3693 +/- 745 pg/100 microl in IL-12-treated mice at day 5. IFNgamma levels were undetectable at day 13 in controls and 1335 +/- 220 pg/100 microl in IL-12-treated mice. Cytokine production was also assessed at the single-cell level for mediastinal lymph nodes. IL-12 treatment increased the number of IL-2- and IFNgamma-producing cells and decreased the number of IL-4- and IL-10-producing cells. IL-12 treatment decreased the anti-influenza antibody response, especially anti-influenza IgG1 antibody resulting in an increased IgG2a/IgG1 ratio. Primary pulmonary CTL activity on day 5 was low for both groups (10% specific lysis). Secondary CTL activity at day 11 was higher for control mice than for IL-12-treated mice on day 11 (44 versus 34%), but not on day 13. Despite this overall enhancement of Th1-mediated immune functions, the IL-12 treatment increased severity of the disease. Following infection, control and IL-12-treated mice decreased their body weight to approximately 75% of their initial weight. After day 5, the control mice started to recover, while IL-12-treated mice did not begin recovering until day 9. Pulmonary viral titers were 1.6 +/- 0.3 TCID50 in controls at day 5 compared to 2.4 +/- 0.3 for IL-12-treated mice (P < 0.01). In addition, control mice had significantly less severe inflammation and damage on histologic examination. Serum TNFalpha concentrations, undetectable in control mice, were elevated by IL-12 treatment up to 80 pg/ml at day 5 and decreased to zero at day 13. It is concluded that IL-12 administration to influenza-infected mice induces a switch from a Th2- to a Th1-mediated response, but inhibits recovery probably through induction of TNFalpha.