Primary influenza A virus infection induces cross-reactive antibodies that enhance uptake of virus into Fc receptor-bearing cells

Sera of young children who had had a primary infection with influenza A virus or were immunized with a live attenuated influenza A virus vaccine were examined for antibody responses that neutralized virus or enhanced uptake of virus into Fc receptor-bearing cells, because antibodies that enhance uptake of influenza virus into Fc receptor-bearing cells have been reported using mouse immune serum and monoclonal antibodies. The neutralizing antibody titers to the homologous infecting virus and to another H1N1 virus isolated several years later were higher after natural infection than after infection with the live attenuated virus. Natural infection and the attenuated vaccine induced antibodies that enhanced uptake of homologous virus and H1N1 virus isolated several years later. These results demonstrate that primary influenza A virus infection results in the induction of infection-enhancing antibodies.     

Electrocatalytic reduction of hydrogen peroxide at a stationary pyrolytic graphite electrode surface in the presence of cytochrome c peroxidase: a description based on a microelectrode array model for adsorbed enzyme molecules

Electrochemical reduction of H2O2 at pyrolytic graphite disc electrodes of radius 2.5 mm occurs at readily accessible potentials (600 mV versus the standard hydrogen electrode) in the presence of yeast cytochrome c peroxidase. Introduction of the enzyme into the electrolyte solution initiates large changes in the ellipsometric angles measured for the electrode-solution interface, consistent with time-dependent enzyme adsorption. This process may be correlated with changes in electrochemical activity. Over the same time course, linear-sweep voltammograms are characterized by a transition from a sigmoidal to a peak-type waveform. It is proposed that the time-dependent behaviour may be rationalized by use of a microscopic model for substrate mass transport, in which the two-electron reduction of peroxide occurs at electrocatalytic sites consisting of adsorbed enzyme molecules. A voltammetric theory based on treating the adsorbed redox enzymes as an expanding array of microelectrodes is in excellent agreement with experiment.     

Effects of acute stress on lymphocyte beta 2-adrenoceptors in white males

The effects of acute cold pressor stress on peripheral blood cells and lymphocyte beta 2-adrenoceptor density and affinity were examined in 18 young, healthy normal white male volunteers. Blood samples were drawn two times before and three times after the stressor. The percents of lymphocytes and neutrophils, plasma cortisol and the beta 2-adrenoceptor density were significantly different among blood samples. There were no differences between samples in total white blood cell count, and percent of monocyte, basophil and eosinophil or beta 2-adrenoceptor affinity. The results suggest that cold pressor stress causes lymphocytosis and increases the lymphocytic beta 2-adrenoceptors concentration. Methodological issues, acute vs chronic condition effects, immune cell subset variations and the psychosomatic activity-affect model were discussed. Such adrenoceptor changes may provide one mechanism by which stress can affect the onset of cardiac/hypertensive disorders.     

Identification and characterization of a binding site for factor XIIa in the Apple 4 domain of coagulation factor XI

Previously we have characterized a binding site for high M(r) kininogen in the first of four tandem-repeat (Apple) domains within the heavy chain region of factor XI (Baglia, F. A., Jameson, B. A., and Walsh, P. N. (1990) J. Biol. Chem. 265, 4149-4154; Baglia, F. A., Jameson, B. A., and Walsh, P. N. (1991) J. Biol. Chem. 267, 4247-4252), whereas a substrate binding site for factor IX was localized to the second Apple (A2) domain (Baglia, F. A., Jameson, B. A., and Walsh, P. N. (1991) J. Biol. Chem. 266, 24190-24197). To define the factor XI domain that binds factor XIIa, we have screened a panel of synthetic peptides for their capacity to inhibit factor XI activation by factor XIIa. Peptide Gly326-Lys357 (located in the A4 domain) is a noncompetitive inhibitor of factor XI activation by factor XIIa (Ki = 3.75 microM), whereas structurally similar peptides from the A1, A2, and A3 domains were required at > 1000-fold higher concentrations for similar effects. The same peptide (Gly326-Lys357) is a competitive inhibitor of factor XIIa amidolytic activity (Ki = 3.8 microM) suggesting that it binds near the active site of factor XIIa. Computer modeling was used to predict the secondary and tertiary structure of the A4 domain of factor XI that interacts with factor XIIa. Rationally designed, conformationally constrained peptides were synthesized comprising residues Ala317-Gly326, Lys331-Lys340, and Gly344-Gly350, which act in concert to inhibit factor XI-activation by factor XIIa. Finally, a conformationally constrained peptide spanning residues Ala317-Gly350 inhibits factor XIIa-catalyzed factor XI activation 50% at a concentration of 5 x 10(-7) M. These results, interpreted in the context of the model, suggest that the sequence of amino acids from Ala317 through Gly350 of the heavy chain of the A4 domain of factor XI contains three peptide structures, possibly consisting of three antiparallel beta-strands that together comprise a contact surface for interacting with factor XIIa.     

Allogeneic-syngeneic cultured epithelia. A successful therapeutic option for skin regeneration

Organ transplantation has progressed rapidly during the last decades. Furthermore, tissue engineering has and will continue to enlarge the scope of organ grafting. Thus, severe skin wounds, as observed in large burn trauma patients, can now be permanently treated with cultured autologous epithelial sheets. However, the time required for autologous cell growth is a major limitation. We propose to alleviate this pitfall through a novel chimeric (allogeneic-syngeneic) epithelial cell culture technique. These chimeric epidermal grafts implanted in an animal model have been shown to allow the reappearance of a histologically normal epidermal coverage similar to simultaneously performed isografts. The regenerated epidermis contained only syngeneic keratinocytes. Thus, allogeneic cells were eliminated passively. This new culture technology could find multiple applications, notably in various skin disease therapies.     

Tropical sprue in travelers and expatriates living abroad

Changes in the world political situation, the rapidity of transportation, and the availability of effective therapy have altered the pattern of sprue in persons going to the tropics. Gone, for the most part, are the days when expatriates liver for years in tropical areas, progressed on the full-blown pattern of debilitating disease when they acquired sprue, and then were never totally cured either by return home or by the then-available forms of therapy. Today, visitors to the tropics usually return home by jet aircraft within weeks or months after acquiring the disease, and thus they present just with manifestations of small bowel disease in the absence of nutritional deficiencies. In this circumstance, the differential diagnosis usually lies between sprue and giardiasis. Both of these disorders are caused by chronic contamination of the small bowel by enteric pathogens, and both can be cured by specific therapy directed at eradicating these organisms. In contrast to the situation in travelers, sprue among the indigenous population of the tropics remains largely unchanged: a chronic debilitating disorder that represents a significant contributory factor to the pathogenesis of morbidity and malnutrition in some areas.     

Contemporary methods of the target puncture of the mammary gland

New accurate methods of puncture of the mammary gland, making use of preliminary layout using roentgenograms, coordination nets, Cytoguide comprter device, and ultrasound-monitored spot biopsy replaced the traditional poorly informative methods. Sonography-monitored puncture is the most informative in cases with both palpated and unpalpated formations shaped as nodules: it permits imaging in 85% of cases. However, in 25-30% of cases unpalpated cancer presents as microcalcinates and cord-like restructuring which cannot be imaged on sonograms. Moreover, unpalpated cancer presenting as a nodule against the background of fatty involution also may be undiscernible on sonograms. In such cases puncture controlled by roentgenography with a computer device and a relevant kit of disposable instruments is advisable, giving accurate information in 61.1% of cases.     

Identification of a novel amide peptide, GLTPNMNSLFF-NH2, involved in the control of vas deferens motility in lymnaea stagnalis

Peptide messengers are crucial for the execution of male copulatory processes in the snail Lymnaea stagnalis. In this study, we report the purification of a novel peptide from the penis complex of L. stagnalis. This peptide enhances the contraction frequency and contraction amplitude of the vas deferens. Amino acid sequencing and mass spectrometry indicate that the primary structure is GLTPNMNSLFF-NH2. We propose that this amide peptide modulates the transfer rate of semen in the vas deferens.