Citations

Abstract Basophils infiltrate the skin and other tissues as part of T lymphocyte and/or antibody-mediated immune responses to certain protein antigens, viruses, tumors, and parasites. Although basophils may comprise a significant fraction of leukocytes in these reactions, their precise role has been poorly understood. Guinea pigs expressing acquired immunity to the tick Amblyomma americanum develop basophil- and eosinophil-rich cutaneous inflammatory responses at tick feeding sites, and tick rejection is associated with extensive local basophil degranulation. We report that a specific anti-basophil serum (ABS) eliminate basophils at tick feeding sites and abolished immunity to A. americanum. ABS does not react with eosinophils and did not reduce blood or bone marrow eosinophils; however, ABS-treated animals had diminished eosinophils at tick feeding sites, perhaps because these sites were deficient in basophil-derived eosinophil-chemotactic factors. AES treatment markedly reduced feeding site eosinophils, did not affect basophil levels, and partially impaired tick resistance. Taken together, our experiments suggest cooperation between basophils and eosinophils in the expression of immunity to ticks in guinea pigs.

Abstract The plasma membrane serves as an important site for the interaction of macrophages and lymphocytes in antigen recognition and of macrophages and foreign agents in inflammatory responses. Despite the critical role of the macrophage membrane in these reactions, studies on the biochemical and functional characteristics of macrophage membranes which need to be performed have been limited by the lack of suitable methods for the isolation of macrophage plasma membranes that maintain functional and antigenic membrane markers. Recently a new method for membrane isolation has been reported which is based on the observation that a variety of sulfhydryl blocking agents can induce the shedding of plasma membrane vesicles of monolayer cell lines. In this paper we demonstrate that guinea pig peritoneal exudate macrophages can also be induced to shed significant quantities of plasma membrane vesicles by such reagents, in particular with a low m.w. aldehyde, and that these vesicles can be isolated by centrifugation. Vesiculation in macrophages is potentiated by disulfide reducing agents, such as dithiothreitol, and by calcium ions. Maximum vesiculation is observed when well spread macrophage monolayers are incubated in a slightly hypertonic vesiculant at pH 7.0 for 2 hr at 37°C. Brief exposure of macrophages to a vesiculant for intervals as short as 30 min is also effective. Macrophage vesicles shed from the cell surface by this procedure have been found to contain receptors for concanavalin A, wheat germ agglutinin, phytohemagglutinin, and lentil lectin. Vesicles also contain Fc and complement (C3) receptors and form rosettes with thymic lymphocytes. It is suggested that macrophage plasma membrane vesicles isolated by this technique should serve as a valuable new system to study the biochemical characteristics of macrophage plasma membranes and their role in immunologic reactions.

Abstract Although the eosinophil has been recognized as a distinctive cell type for almost 100 years, the major functions of these cells remain unknown. As an approach to defining these functions we have treated guinea pigs with rabbit antiserum to eosinophils (AES) in an attempt to ablate these cells from tissues. Rabbits were immunized thrice with purified eosinophils and the antisera were absorbed with peripheral blood cells from guinea pigs made eosinopenic with methyprednisolone to remove antibodies reactive with serum proteins and erythrocytes. The resulting sera reacted strongly with eosinophils in cytotoxicity tests and had weak or no reactivity with neutrophils. However, absorption of AES with purified neutrophils removed anti-eosinophil activity. Intraperitoneal injection of potent AES into guinea pigs resulted in complete absence of eosinophils from the peripheral blood and from the peritoneal cavity with only transient or no reduction in circulating neutrophils. Eosinophils were also reduced in bone marrow, spleen, and intestine. The ability of neutrophils to absorb AES activity in spite of weak reactivity in cytotoxicity tests may reflect a quantitative difference in antigenic determinants between eosinophils and neutrophils.

Background: Clinical trials are currently underway to investigate the efficacy of intra-articular administration of mesenchymal stromal cells (MSCs) to mitigate osteoarthritis (OA) progression in the knee. Although multiple MSC sources exist, studies have yet to determine whether differences in therapeutic efficacy exist between them. Purpose: To compare the ability of intra-articularly injected adipose-derived MSCs (AD-MSCs) and amnion-derived MSCs (AM-MSCs) to mitigate the progression of knee OA in a small animal model of spontaneous OA, as well as to compare the therapeutic potential of MSCs in hyaluronic acid (HA) and in HA only with saline (OA) controls. Study Design: Controlled laboratory study. Methods: Injections of AD-MSCs or AM-MSCs suspended in HA or HA only were performed in the rear stifle joints of 3-month-old Dunkin Hartley guinea pigs (DHGPs). Repeat injections occurred at 2 and 4 months after the initial injection in each animal. Contralateral limbs received saline injections and served as untreated controls. Subsequently, joints were analyzed for osteoarthritic changes of the cartilage and subchondral bone via histologic and biochemical analyses. To evaluate MSC retention time in the joint space, DHGPs received a single intra-articular injection of fluorescently labeled AD-MSCs or AM-MSCs, and the fluorescence intensity was longitudinally tracked via an in vivo imaging system. Results: No statistically significant differences in outcomes were found when comparing the ability of AD-MSCs and AM-MSCs to mitigate OA. However, the injection of AD-MSCs, AM-MSCs, and HA-only treatments more effectively mitigated cartilage damage compared with that of saline controls by demonstrating higher amounts of cartilage glycosaminoglycan content and improved histological proteoglycan scoring while reducing the percentage of osteophytes present. Conclusion: Intra-articular injection of AD-MSCs, AM-MSCs, or HA only was able to similarly mitigate the progression of cartilage damage and reduce the percentage of osteophytes compared with that of saline controls in the DHGP. However, this study was unable to establish the superiority of AD-MSCs versus AM-MSCs as a treatment to mitigate spontaneous OA. Clinical Relevance: MSCs demonstrate the ability to mitigate the progression of knee OA and thus may be used in a prophylactic approach to delay the need for end-stage treatment strategies.

Abstract Megaloblastosis has been produced in young guinea pigs by feeding them purified diets deficient its pteroylglutamic acid (PGA) or vitamin B12 or both. The withholding of ascorbic acid from the diet did not produce megaloblastosis but it greatly enhanced its development when PGA was also withheld. Spontaneous remission took place in several instances. The possible role of growth of the animal and changes in the bacterial flora of the gastrointestinal tract has been discussed. Bacteriologic studies appeared to indicate a possible interrelationship between the occurrence of Escherichia coli in the stools of guinea pigs consuming deficient diets and the development of megaloblastosis. Diarrhea and infections are considered important in the pathogenesis of megaloblastic anemia but infections were not observed in animals of the present study. However, diarrhea was a prominent feature and appeared to be a factor associated with megaloblastosis. Anemia was usually present in association with megaloblastosis; however, megaloblastosis of a mild degree appearing in some of the animals fed the diets deficient in PGA or vitamin B12 was not accompanied by anemia. When ascorbic acid was withheld in addition, then anemia always developed. A dimorphic picture of macrocytosis and microcytosis was found most commonly in the peripheral blood of animals with megaloblastosis. This has been explained on the basis of regenerative macrocytosis or as a disturbance of the maturation of erythrocytes in such deficiencies. Data obtained from peripheral blood are not a reliable indicator of megaloblastosis, nor is the clinical condition of the animal indicative of the pathologic state. One animal which had been fed a diet deficient in vitamin B12 and PGA and which showed megaloblasts in its bone marrow was given injections of vitamin B12. The megaloblastosis was corrected but the animal died on the sixteenth day of treatment. Two animals fed diets deficient in PGA and ascorbic acid were subsequently given injections of PGA and ascorbic acid. The results demonstrated that administration of ascorbic acid alone did not interrupt the development of severe megaloblastosis in the continuing absence of PGA. When PGA was given, reticuocytosis then ensued and there was a reversal of megaloblastic erythropoiesis.

Although the Sensititre Yeast-One (SYO) and Etest methods are widely utilized, interpretive criteria are not available for triazole susceptibility testing of Candida or Aspergillus species. We collected fluconazole, itraconazole, posaconazole, and voriconazole SYO and Etest MICs from 39 laboratories representing all continents for (method/agent-dependent) 11,171 Candida albicans , 215 C. dubliniensis , 4,418 C. glabrata species complex, 157 C. guilliermondii ( Meyerozyma guilliermondii ), 676 C. krusei ( Pichia kudriavzevii ), 298 C. lusitaniae ( Clavispora lusitaniae ), 911 C. parapsilosis sensu stricto , 3,691 C. parapsilosis species complex, 36 C. metapsilosis , 110 C. orthopsilosis , 1,854 C. tropicalis , 244 Saccharomyces cerevisiae , 1,409 Aspergillus fumigatus , 389 A. flavus , 130 A. nidulans , 233 A. niger , and 302 A. terreus complex isolates.

Airway function is largely preserved during exercise or isocapnic hyperventilation in humans and guinea pigs despite likely changes in airway milieu during hyperpnea. It is only on cessation of a hyperpneic challenge that airway function deteriorates significantly. We tested the hypothesis that nitric oxide, a known bronchodilator that is produced in the lungs and bronchi, might be responsible for the relative bronchodilation observed during hyperventilation (HV) in guinea pigs. Three groups of anesthetized guinea pigs were given saline and three groups given 50 mg/kg NG-monomethyl-l-arginine (l-NMMA), a potent nitric oxide synthase inhibitor. Three isocapnic ventilation groups included normal ventilation [40 breaths/min, 6 ml/kg tidal volume (Vt)], increased respiratory rate only (150 breaths/min, 6 ml/kg Vt), and increased respiratory rate and increased volume (100 breaths/min, 8 ml/kg Vt). l-NMMA reduced expired nitric oxide in all groups. Expired nitric oxide was slightly but significantly increased by HV in the saline groups. However, inhibition of nitric oxide production had no significant effect on rate of rise of respiratory system resistance (Rrs) during HV or on the larger rise in Rrs seen 6 min after HV. We conclude that nitric oxide synthase inhibition has no effect on changes in Rrs, either during or after HV in guinea pigs.