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Biomedical subjects

B Hammerberg

Publications and source records attributed to B Hammerberg.

At least 37 records · Page 2Linked to original sources
PubMed1988

Taenia taeniaeformis: cellular reconstruction of athymic mice and role of L3T4+ helper T lymphocytes in the early infection.

The role of T helper lymphocytes (L3T4+) in the early response to Taenia taeniaeformis metacestodes was investigated. Athymic BALB/c-nu/nu mice (susceptible) were inoculated intraperitoneally with the following cell populations from congenic BALB/c-nu+ + mice (resistant): (a) whole spleen single cells, (b) thymus single cell suspensions, or (c) spleen cells pretreated with anti-L3T4 monoclonal antibody before the injection. The mice were given 3 weekly injections of cells and then infected orally with 300 eggs 7 days after the last injection. Cryostat sections of the liver from the infected mice were examined at 6 days postinfection (PI) for parasite viability, the numbers of eosinophils, and L3T4+ T lymphocytes present within 100 micron of the parasite and for the presence of biotin in hepatocytes (involved in biosynthesis of fatty acids) around the parasite. The success of the cellular reconstitution of athymic mice with the lymphoid cells was measured by a T-cell mitogenic assay with concanavalin A (ConA). The cellular reconstitution of athymic mice with a mixture of lymphoid cells from the spleen and thymus of BALB/c-nu/ + mice resulted in both parasite death and eosinophil infiltration. Reconstitution with mature splenic cells alone resulted in a greater parasite killing and eosinophil infiltration as compared to reconstitution with thymic cells. The better reconstitution with splenic cells was reflected in a greater mitogenic response to ConA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Dynamics of immune responses related to clinical status in Brugia pahangi-infected dogs.

Clinical signs of lymph node enlargement, limb edema, lymph duct fibrosis, and microfilaremia were monitored in dogs with chronic Brugia pahangi infections. During the study a single rear limb of each dog was reinfected with multiple low doses of infective larvae. The changing immune responses to parasite antigens prepared from three sources--Brugia pahangi adult worm homogenate extract, adult worm excretory-secretory products, and microfilaria excretory-secretory products--were monitored by Western blot ELISA of antigens fractionated on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and by microtiter plate ELISA. Assays were used to detect antibodies in both the the IgG and IgE classes. A wide range of clinical manifestations was demonstrated in response to reinfection: asymptomatic, amicrofilaremic; asymptomatic, microfilaremic; acute short duration node enlargement and/or limb edema with microfilaremia; and chronic limb edema, amicrofilaremic. On microtiter plate ELISA, the dogs demonstrating the highest anti-adult worm homogenate titers were amicrofilaremic and were asymptomatic or developed chronic limb edema, dogs with high anti-mf ES titers were persistently amicrofilaremic, and the most marked increases against all three antigen sources upon reinfection occurred in low or amicrofilaremic dogs. Quantitative changes in antibody levels against the three crude antigen sources following reinfection were often paralleled by distinct changes in recognition of specific bands of antigens fractionated by SDS-PAGE.

Animals↗
PubMed1986

Clinical and xeroradiographic lymphangiography studies of acute and chronic Brugia pahangi infections in dogs.

Xeroradiographic lymphangiography was carried out at approximately monthly intervals on five dogs during the first 18 weeks following infection with 400 Brugia pahangi infective larvae in the left rear paw. Clinical signs, body temperatures and microfilaria counts were also monitored during this time. Similar observations were made on nine dogs with chronic infections (one to five years duration) of 200 infective larvae in unilateral inguinal sites. Standard thoracic radiography was conducted on all dogs. Surgical occlusion of the major afferent ducts to the popliteal lymph nodes of the infected and noninfected limbs of a chronically infected dog was performed to study oedema induction and resolution. This non-invasive lymphangiographic technique demonstrated marked differences in lymphatic changes among individual dogs. The severity of lymphatic pathology correlated with clinical signs of limb oedema and low microfilaria counts. Chronically infected dogs also demonstrated a variety of pathological manifestations: two dogs presented lymphatic cording and another showed transient lymphadenitis with fever and pulmonary arterial opacities. Surgical occlusion of major lymphatic ducts in an uninfected limb resulted in short-term oedema, while occlusion caused by B. pahangi in acutely infected dogs resulted in more persistent oedema. Surgical occlusion of a major duct in a chronically infected limb did not result in oedema. Xeroradiographic lymphangiography revealed a spectrum of lymphatic pathology in Brugia pahangi-infected dogs and demonstrated the value of this animal model for the study of the pathogenesis of chronic lymphatic filariasis.

Animals↗
PubMed1986

Pathophysiology of nematodiasis in cattle.

Recent detailed studies of the physiologic changes occurring in cattle infected with some of the common gastrointestinal nematodes have shown that the weight loss and reduced carcass values resulting from these infections are a consequence of major alterations in host metabolism. Dramatic changes in protein metabolism were consistently found to involve decreased muscle synthesis and increased urinary nitrogen excretion. Because of the well-recognized loss of plasma proteins into the gut lumen and cellular damage at the mucosa occurring during nematode infections of the abomasum and duodenum, it has been assumed that protein was being lost in feces or not absorbed; however, this loss has proved not to be as significant as postabsorptive protein catabolism in these infections. Only when the colon and cecum are involved in protein-losing infections is the loss of protein into the feces significant. The mechanisms by which gastrointestinal nematode infections result in such altered host metabolic states are not known, but suggestions have been made that parasites directly or indirectly alter gut hormone levels. Gut hormone changes may also be responsible for diarrhea and anorexia. Another mechanism of altering metabolism has been proposed for chronic parasitisms that stimulate macrophages. Macrophages produce a peptide called cachectin, and cachectin is thought to mediate protein and lipid catabolism. This mechanism obviously could be contributing to weight loss and anorexia whenever nematodes cause sufficient macrophage activation, including during lungworm infections, which do not have enteric involvement.

Animals↗
PubMed1985

Sheathed and unsheathed microfilarial surfaces, interactions with host serum proteins in diethylcarbamazine.

There is no question that when a high titer of antibodies specific for microfilaria (mf) surfaces is present in assays of granulocyte adherence that cell binding is greater than in normal serum. It is also well documented that complement intact serum with or without surface specific antibody permits the deposition of C3 on mf, and surface bound C3b is known to facilitate adherence by granulocytes and especially eosinophils. How diethylcarbamazine enhances cell adherence to mf surfaces directly or as mediated by specific antibody, complement or as yet untested serum components such as eosinophil granule major basic protein (MBP) remains unknown. In reviewing work which has attempted to investigate this question, it was found that there were several possible sources of inconsistencies in the reagents usually employed in the cell adherence experiments with mf and some of these may have already contributed to confusion in the interpretation of results reported to date. Firstly, eosinophils collected from individuals with high eosinophil counts appear to be more reactive than those from normal donors. Secondly, Brugia pahangi mf taken in early patent infections or from very high microfilaremic infections in cats are less reactive with granulocytes than those from more long-term infections and this may be related to the differences in surface carbohydrate composition detected among mf taken from uteri of adult females, in vitro released mf and mf collected from host tissue. Thirdly, higher levels of MBP may be present in serum from individuals with high eosinophil counts associated with filarial infection than in serum from normal controls.

Animals↗
PubMed1984

Immunoglobulin interactions with surfaces of sheathed and unsheathed microfilariae.

The sheath surface of Brugia pahangi microfilariae (mf) and the cuticle surface of Dirofilaria immitis mf were compared with regard to the ultrastructural arrangement of neutral and charged polysaccharides and binding of immunoglobulins from dog sera. Brugia pahangi: mf demonstrated large amounts of neutral sugar and negatively charged sugars just above the sheath surface, projecting some distance from the surface, in addition to a dense layer of sulphated material on the sheath surface. Microfilariae from high microfilaremic dogs showed no innately bound IgG or IgM when examined fresh from serum nor did they bind IgG or IgM from normal (NDS) or infected (IDS) dog sera after 48 h maintenance in RPMI 1640. Many of these mf did bind IgG and IgM from hyperimmune dog serum (ImDS) and these immunoglobulins were found binding at a distance from the sheath similar to that of the sugars. Dirofilaria immitis mf demonstrated much less neutral sugar at the cuticle surface, no negatively charged sugars and a diffuse, rather than dense, distribution of sulfated material extending from the cuticle. The majority of these mf showed innately bound IgG and IgM. After 48 h maintenance in RPMI 1640 D. immitis mf bound and shed IgG and IgM from NDS, high microfilaremia D. immitis IDS and D. immitis mf ImDS at distinctly different rates.

Animals↗
PubMed1983

Third component of complement, immunoglobulin deposition, and leucocyte attachment related to surface sulfate on larval Taenia taeniaeformis.

Cysticerci and strobilocerci of Taenia taeniaeformis were incubated with leucocytes from peritoneal washings of normal and T. taeniaeformis-infected rats in the presence of either normal sera or sera from infected rats. Leucocytes from infected and normal rats attached exclusively to the scolices but not the bladders of the larvae in the presence of serum from normal or infected rats. Heat inactivation at 56 C for 30 min destroyed the serum-mediated cell attachment. Histochemical staining of the larval taeniids with acid Alcian Blue demonstrated high concentrations of sulfated mucopolysaccharides on bladders that were not present on scolices. Immunofluorescent staining detected no difference in IgG deposition on the surfaces of bladders and scolices after incubation with rat sera in contrast to the markedly greater amounts of complement protein C3 found on scolices versus bladders. These results indicate that polysulfated substances on the bladder of this larval taeniid are associated with regional resistance to C3 deposition and leucocyte attachment.

Animals↗
PubMed1982

Diethylcarbamazine-enhanced activation of complement by intact microfilariae of Dirofilaria immitis and their in vitro products.

Microfilariae of Dirofilaria immitis and their products inhibited hemolytic complement in sera from various animal species. Inhibition of hemolytic complement activity, fluorescent antibody detection of specific complement proteins binding to microfilarial surfaces, and immunoelectrophoretic evaluation of complement protein C3 conversion demonstrated that (1) intact microfilariae depleted hemolytic complement activity maximally in the presence of diethylcarbamazine whereas the complement-fixing activity of microfilarial products was little affected by diethylcarbamazine; (2) complement proteins C3, properdin, and C5 bound to the cuticular surface of microfilariae; and (3) C3 was converted to a faster-migrating species during incubation with microfilariae or their products. The complement-depleting activity of in vitro products from viable microfilariae was soluble in 10% trichloroacetic acid, resistant to beta-elimination with 0.5 M NaOH, susceptible to treatment with 0.2 M periodate, and composed of 56% neutral sugar, 18% protein, 12% hexosamine, and 10% sulfate. The polysulfated, acidic mucopolysaccharide nature of the surfaces of microfilariae and the results presented here indicate that polyanionic components on worm surfaces or shed by microfilariae react with host complement proteins. This interaction may be enhanced by diethylcarbamazine and contribute to the pathology associated with microfilaremias.

Animals↗
PubMed1980

Changes in periparturient fecal egg counts in beef cows calving in the spring.

A herd of mature Angus and Angus-Holstein-Friesian cows calving between March and May was maintained at 80% and 100% of National Research Council's recommended total digestible nutrient (TDN) levels during the winter. Changes in fecal nematode egg counts of these cows, expressed as eggs/5 g of feces and quantitated by the Wisconsin sugar flotation technique, were detected perinatally and were correlated with breed, nutritional level, and time of year. A limited, yet highly significant (P less than 0.001) increase in egg output was found in cows at calving. Anthelmintic treatment at calving caused postcalving egg counts that were statistically lower than were those from non-treated cows. When breed and nutritional level were considered independently, there was less influence on egg counts than when the interaction of breed and nutritional level was examined. Angus-Holstein-Friesian cows fed 80% TDN requirements had the greatest perinatal increase in egg output, and those fed 100% TDN had the smallest increase of all groups. Angus cows responded in an opposite manner to the nutritional level and had increases in egg counts intermediate to those counts of Angus-Holstein-Friesian cows. This characterization of the periparturient egg output by mature cows aided in evaluating the role of grazing cows in contaminating pastures.

Animals↗
PubMed1978

Interaction between Taenia taeniaeformis and the complement system.

Factors present in the cystic bladder fluid of metacestodes of Taenia taeniaeformis and released by these parasites maintained in vitro were shown to interact with the C system in vitro and in vivo. This interaction resulted in the depletion of hemolytic C in normal sera of several species, the generation of anaphylatoxin-like activity in vitro, the conversion of C3, and the production of vascular permeability changes in vivo. The substances appeared to initiate C fixation nonimmunologically via both the alternative and classical pathways. Intravenous administration of parasite factors in rats led to profound depression of circulating C levels and the rats did not become refractory to this effect after repeated dosing over a 3-week period. Circulating levels of hemolytic C were not altered in infected rats over the first 8 weeks of infection. C-dependent inflammatory responses in the skin of rats were inhibited in animals given i.v. doses of parasite factors. The possibility is raised that local consumption of C around the metacestode in vivo could contribute to its successful evasion of inflammation and immune rejection during infection.

Animals↗
PubMed1977

Uptake of colostral immunoglobulins by the suckling rat.

The sequential appearance of immunoglobulins was studied in serum samples from rats during the suckling period. At birth both IgG1 and IgG2 were present, but IgM was not detected until the 7th day and IgA until the 17th day. No intestinal transmission of intact homologous IgA was demonstrable after oral administration of radiolabelled preparations (125I) of either serum or colostral IgA to suckling rats. When 125I labelled IgG 2a+b rat immunoglobulins were given orally there was a selective transport of the slower moving subclass from the gut into the serum. The rat appeared to differ from several other species in which some intestinal absorption of passively transferred IgA by the newborn has been demonstrated. It was suggested that retention of colostral and milk IgA in the intestine may serve to enhance local defense mechanisms in the newborn rat.

Animals↗
PubMed1977

Activation of complement by hydatid cyst fluid of Echinococcus granulosus.

Factors present in hydatid cyst fluid of Echinococcus granulosus were found to interact with complement from several species. This nonimmunologic fixation resulted in the depletion of hemolytically active complement from fresh guinea pig serum, the conversion of human C3 to an electrophoretically faster species and the genration of smooth muscle contracting substances, analogous to anaphylatoxins, in normal rat serum in vitro. Vascular permeability changes were produced in vivo in rats and humans after intradermal inoculation of complement interacting fractions of hydatid fluid. It is suggested that these factors may contribute to the pathogenesis of the shock syndrome which follows intravenous administration of hydatid fluid in normal animals, and to the nonspecificity of immunodiagnostic skin tests for hydatid infection in man and animals.

Anaphylatoxins↗
PubMedDate not supplied

The lymphatic pathology of chronic Brugia pahangi infection in the dog.

The dog infected with Brugia pahangi is an excellent model for studying the clinical and immunological pathogenesis of lymphatic filarial infection and disease. Dogs demonstrated a range of clinical changes including varying levels of microfilaraemia, episodic lymphadenopathy, lymphangitis, and limb oedema similar to the clinical spectrum reported in man. Histologically, tissues from parasite-infected dogs were characterized by fibrosis of the lymph nodes and their afferent and efferent lymphatic ducts in the infected limbs. Some nodes were atrophied while others were characterized by reactive hyperplasia. Duct walls of some afferent lymphatics were thickened with a mononuclear inflammatory infiltrate. Parasite antigen deposition was detected in the subcapsular sinuses and middle of germinal centres of infected popliteal lymph nodes, using an immunohistochemical technique.

Animals↗