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Biomedical subjects

A Hoek

Publications and source records attributed to A Hoek.

At least 37 records · Page 2Linked to original sources

The immune response of cattle, persistently infected with noncytopathic BVDV, after superinfection with antigenically semi-homologous cytopathic BVDV.

Cattle persistently infected (PI) with noncytopathic (ncp) bovine virus diarrhea virus (BVDV) are at risk for developing fatal mucosal disease (MD), which is considered to occur after superinfection with antigenically homologous cytopathic (cp) BVDV. In this study, we intranasally inoculated four PI-animals, that were PI with 2 ncp BVDV strains with 10(5) TCID50 antigenically closely related cp BVDV. Two PI-animals were inoculated with 10(5) TCID50 ncp BVDV and one PI-animal, with virus free cell culture medium. Two out of four PI-animals that were inoculated with cp BVDV, developed MD and were euthanized at day 17 and at day 24 after infection. Postmortem, both animals showed typical lesions of MD and cp BVDV was isolated. The other two PI-animals that were inoculated with cp BVDV did not develop MD and were euthanized at day 51. They showed ulcerations in the gastrointestinal tract, cp BVDV was isolated and neutralizing antibodies were detected. From the three PI-animals, that were inoculated with ncp BVDV or cell culture medium, cp BVDV was also isolated. Cross neutralization tests were performed and no antigenic differences could be detected between the cp strains isolated from the PI-animals. Lymphocyte subsets of these PI-animals were determined by flow cytometric analysis. Before superinfection, the percentages of gamma delta subsets were much higher in the PI-animals that did not develop MD than in nonviremic control animals and in the PI-animals that died of MD. From this study we conclude that the presence of antigenically closely related cp BVDV in PI-animals does not necessarily lead to the development of MD and that besides the antigenic relatedness between the persisting ncp BVDV and cp BVDV other factors, for instance the number of circulating gamma delta cells, might determine whether or not PI-animals develop MD.

Animals↗

Impaired specific immunoreactivity in cows with hepatic lipidosis.

In this study, hepatic lipidosis in cows was experimentally induced by offering an energy surplus during the dry period. Liver triacylglycerol (TAG) was 16% in the experimental group. In the control group fed the same diet in restricted quantities, liver TAG was about 7%. The animals of both groups were vaccinated with tetanus vaccine at Day 3 after parturition. It was demonstrated that the cows with high liver TAG percentages had lower humoral and cellular (P < 0.05) immunological responses compared with the animals with low liver TAG levels at Day 14 after vaccination. The results obtained in the high TAG group support the notion that the frequent occurrence of aspecific infections in cows with hepatic lipidosis may be due to impaired immunoreactivity.

Animals↗

Antigen-specific immune responses in cattle with inherited beta2-integrin deficiency.

The significance of beta2-integrins for the generation of antigen-specific immune responses in vivo was studied employing the bovine model of beta2-integrin deficiency. To that end four cattle with bovine leukocyte adhesion deficiency (BLAD) and healthy age-matched controls were immunized with tetanus toxoid (TT) and rabies virus (RV) vaccines three times in monthly intervals. In addition, two animals with BLAD and three controls received a fourth vaccination 8 months after the start of the study. Proliferative responses of peripheral blood mononuclear cells (PBMC) to the antigens TT and RV as well as specific serum immunoglobulin G (IgG) titers were determined in intervals for up to 10 months after primary vaccination. Proliferative responses of PBMC to TT and RV were substantially lower in cattle with BLAD than in controls, although PBMC from cattle with BLAD were shown to have the capacity to proliferate in the response to the mitogen concanavalin A. Occurrence of antigen-specific IgG titers was delayed and they were considerably lower in cattle with BLAD compared to controls. Finally, treatment of TT- and RV-stimulated PBMC from an immunized control with different concentrations of the anti-CD18 monoclonal antibody R15.7 resulted in a dose-dependent inhibition of lymphocyte proliferation to almost 100%. The results of the present study show that beta2-integrin deficiency leads to delayedand severely impaired immune responsiveness in vivo. The observations that antibody production, although considerably delayed and impaired, does occur and that apparently class-switching takes place in BLAD indicate T-cell reactivity in vivo.

Animals↗

Premature ovarian failure and ovarian autoimmunity.

Premature ovarian failure (POF) is defined as a syndrome characterized by menopause before the age of 40 yr. The patients suffer from anovulation and hypoestrogenism. Approximately 1% of women will experience menopause before the age of 40 yr. POF is a heterogeneous disorder with a multicausal pathogenesis involving chromosomal, genetic, enzymatic, infectious, and iatrogenic causes. There remains, however, a group of POF patients without a known etiology, the so-called "idiopathic" form. An autoimmune etiology is hypothesized for the POF cases with a concomitant Addison's disease and/or oöphoritis. It is concluded in this review that POF in association with adrenal autoimmunity and/or Addison's disease (2-10% of the idiopathic POF patients) is indeed an autoimmune disease. The following evidence warrants this view: 1) The presence of autoantibodies to steroid-producing cells in these patients; 2) The characterization of shared autoantigens between adrenal and ovarian steroid-producing cells; 3) The histological picture of the ovaries of such cases (lymphoplasmacellular infiltrate around steroid-producing cells); 4) The existence of various autoimmune animal models for this syndrome, which underlines the autoimmune nature of the disease. There is some circumstantial evidence for an autoimmune pathogenesis in idiopathic POF patients in the absence of adrenal autoimmunity or Addison's disease. Arguments in support of this are: 1) The presence of cellular immune abnormalities in this POF patient group reminiscent of endocrine autoimmune diseases such as IDDM, Graves' disease, and Addison's disease; 2) The more than normal association with IDDM and myasthenia gravis. Data on the presence of various ovarian autoantibodies and anti-receptor antibodies in these patients are, however, inconclusive and need further evaluation. A strong argument against an autoimmune pathogenesis of POF in these patients is the nearly absent histological confirmation (the presence of an oöphoritis) in these cases (< 3%). However, in animal models using ZP immunization, similar follicular depletion and fibrosis (as in the POF women) can be detected. Accepting the concept that POF is a heterogenous disorder in which some of the idiopathic forms are based on an abnormal self-recognition by the immune system will lead to new approaches in the treatment of infertility of these patients. There are already a few reports on a successful ovulation-inducing treatment of selected POF patients (those with other autoimmune phenomena) with immunomodulating therapies, such as high dosages of corticosteroids (288-292).

Addison Disease↗

Dendritic cells and macrophages in the pituitary and the gonads. Evidence for their role in the fine regulation of the reproductive endocrine response.

Blood monocytes are able to mature into macrophages as well as into dendritic cells. Dendritic cells and macrophages have mainly been studied for their function in the immune response, e.g. in the presentation of antigens to lymphocytes and in the phagocytosis/degradation of unwanted material. The cells are also, however, important producers of a variety of signalling molecules and hormones and are thus involved in other physiological functions such as wound healing, the regulation of the microcirculation and the regulation of the function and growth of endocrine cells. This review summarizes the existing evidence for a regulatory role of dendritic cells and macrophages in the function and growth of hormone-producing cells of the pituitary-gonadal axis. It focuses on the presence, localization and phenotype of dendritic cells and macrophages in the anterior pituitary and the gonads, the endocrine regulatory role of cytokines produced by these cells and the existence of putative feedback mechanisms between endocrine cells of the pituitary-gonadal axis and dendritic cells and macrophages. The recognition of a 'floating endocrine-regulatory force' of monocyte-derived cells that also plays a role in the initiation of immune responses has implications for our understanding of the pathogenesis of gonadal and pituitary autoimmune reactions.

Animals↗

Identification of monoclonal antibodies with specificity to alpha- or beta-chains of beta 2-integrins using peripheral blood leucocytes of normal and bovine leucocyte adhesion deficient (BLAD) cattle.

The reactivity of monoclonal antibodies entered in the panels of the Third Workshop on Ruminant Leucocyte Antigens with lymphocytes and monocytes of normal and beta 2-integrin deficient (Bovine Leucocyte Adhesion Deficiency: BLAD) animals was determined by flow cytometry to investigate potential specificities to alpha- or beta-chains of beta 2-integrins. From the 13 monoclonal antibodies that were entered as having specificity for CD11/CD18 antigens, ten were confirmed correct, but three had reactivity with cells from BLAD animals. We conclude that our approach provides an easy way to reliably identify the majority of beta 2-integrin specific monoclonal antibodies.

Animals↗

The effect of cobalt supplementation on the immune response in vitamin B12 deficient Texel lambs.

The effect of cobalt supplementation on the immune reactivity in vitamin B12 deficient lambs was measured by comparing the humoral and cell-mediated immune responses against bovine herpes virus type 1 and Mycobacterium paratuberculosis. In addition, faecal egg counts were performed after natural infection with gastrointestinal nematodes. The experiments were performed with registered Texel twin lambs of the same sex. One lamb of each twin received three cobalt pellets divided over the grazing period. The non-supplemented lambs had lower serum vitamin B12 levels than their supplemented brother or sister. Our results demonstrate significantly lower lymphoblastic responses against Mycobacterium paratuberculosis in non-supplemented lambs compared with supplemented lambs 4 weeks after paratuberculosis vaccination. Vitamin B12 deficient lambs in this study had significant higher faecal egg counts than their supplemented brother or sister after natural infection with gastrointestinal nematodes. No differences were found in total and differential white blood cell counts, in total protein, albumin, alpha-, beta- and gamma-globulin and in antibody production against bovine herpes virus type 1 and Mycobacterium paratuberculosis.

Animals↗

Allograft rejection in cattle with bovine leukocyte adhesion deficiency.

In the present investigation cell-mediated immunity in animals with bovine leukocyte adhesion deficiency (BLAD) was studied by means of skin transplantation experiments. Autograft and allograft behaviour in animals with BLAD was compared with the behaviour of simultaneously transplanted autografts and allografts in healthy controls. Allograft survival time was prolonged in three BLAD cattle (28, 30, and 72 days) compared to six healthy controls (12-14 days). When transplantations were repeated on one animal with BLAD using skin grafts from the same donor, accelerated rejection was observed (allograft survival time decreased from 72 days at primary to 35 days at secondary and to 21 days at tertiary transplantation), suggesting the development of immunological memory. Graft-infiltrating lymphocytes that were obtained from allograft biopsies during the period of rejection, were shown to be from recipient origin (beta 2-integrin negative). Our findings demonstrate that, although prolonged allograft survival is observed in cattle with BLAD, skin allografts are ultimately rejected.

Animals↗

Ovulation induction in premature ovarian failure: a placebo-controlled randomized trial combining pituitary suppression with gonadotropin stimulation.

OBJECTIVES: To determine the effect of pituitary suppression with a GnRH agonist (GnRH-a) on the success of ovulation induction with exogenous gonadotropins in patients with premature ovarian failure (POF). DESIGN: Placebo-controlled, randomized, double-blind study. The data were analyzed with a Fisher exact test. SETTING: A tertiary care academic center for Reproductive Endocrinology and Fertility. PATIENTS: Thirty patients with POF, 15 in each group. INTERVENTIONS: The study consisted of four phases: phase 1, no interventions; phase 2, a 4-week period in which the patients received either 1,000 micrograms intranasal buserelin acetate daily or placebo; phase 3, a 3-week period during which the patients additionally received hMG in weekly augmented doses, two, four, and six ampules daily in the first, second, and third weeks, respectively. Ovulation was induced whenever the follicular diameter reached 18 mm and/or total 24-hour estrogen excretion > 140 micrograms (500 nmol). Luteal support was 5,000 IU hCG every 72 hours; phase 4, no interventions. RESULTS: Follicular growth was seen in five patients of the agonist group and in four patients of the placebo group. Three of 15 patients in the agonist group ovulated versus none in the placebo group. The difference was not statistically significant. CONCLUSIONS: The fact that 3 of 15 cycles cotreated with a GnRH-a were ovulatory versus none in the placebo-treated group appeared not to be enough evidence to demonstrate that pituitary suppression with a GnRH-a improves the success of ovulation induction with exogenous gonadotropins in patients with POF.

Adult↗

Successful treatment of an advanced interstitial pregnancy by sequential systemic and local administration of methotrexate.

A patient is presented with an advanced interstitial pregnancy, diagnosed by transvaginal ultrasound and confirmed by laparoscopy. Amenorrhoea at the time of diagnosis was 57 days. Methotrexate was given systemically (4 x 50 mg i.m.). Because of persisting viability of the fetus, systemic methotrexate treatment was followed by local instillation of methotrexate into the gestational sac (50 mg). Follow-up revealed rapid human chorionic gonadotrophin regression but slow regression of fetal remnants.

Administration, Topical↗

Analysis of peripheral blood lymphocyte subsets, NK cells, and delayed type hypersensitivity skin test in patients with premature ovarian failure.

PROBLEM: Premature ovarian failure (POF) probably belongs to the group of autoimmune endocrinopathies. Cell-mediated immune parameters were investigated. Sex steroids have a profound effect on the immune system. POF patients and postmenopausal control women (PM) were tested with or without estrogen substitution. METHOD: A novel FACS analysis system (using double labeling techniques) was used in 30 patients with POF to enumerate the subjects of peripheral blood lymphocytes and NK cells. Eighteen PM women and 30 healthy men and women served as controls. We also tested the delayed type hypersensitivity skin test (DTH) toward Candida in the POF patient group to be informed on their cell-mediated immune function. RESULTS: The numbers of blood lymphocytes, CD3+, CD4+ and CD8+T cells, were not abnormal in POF patients. However, HLA-DR+T cells were increased in POF patients and in PM women (P < 0.05). These elevated numbers were partially reversible by estrogen substitution. The number of CD19+ cells (B cells) was elevated, whereas CD3-/CD16+/CD56+ cells (NK cells) were decreased in POF patients (P < 0.05), irrespective of estrogen substitution. DTH skin tests toward 0.1% Candidin (0.1 ml intradermal injection) were negative in 11 out of 20 tested POF patients, compared to only 2 out of 10 tested controls (P < 0.05). CONCLUSION: POF patients show numerous immune cell abnormalities. These abnormalities were only partially due to estrogen deficiency. We hypothesize that these abnormalities either lead to ovarian autoimmunity or may have direct effects on the ovarian function.

Adult↗

Bovine leukocyte adhesion deficiency--clinical course and laboratory findings in eight affected animals.

The clinical course of Bovine Leukocyte Adhesion Deficiency (BLAD) in eight Holstein Friesian cattle is described. Affected animals were presented with a history of poor thriving and recurrent bacterial infections. Five of these animals had to be killed because of severe respiratory disease shortly after admittance. Three affected animals survived calfhood only as a result of frequent antibacterial treatments. At one year of age, failure to thrive and stunted growth were still evident, but infections requiring antibiotic treatments occurred only sporadically. Clinical manifestations of BLAD were found in the digestive system (gingivitis, periodontitis, alveolar periostitis, diarrhoea), the respiratory system and the skin (impaired wound healing, chronic dermatitis). A leukocytosis based on a mature neutrophilia, which persisted during infection-free periods, was observed in all animals. Granulocytes were substantially deficient of beta 2-integrin expression on their membranes. Anaemia, which was noted in four animals, may be related to the Anaemia of Inflammatory Disease Complex (AID). The serum total protein content increased with time and was associated with elevated gamma-globulin levels. We suggest that, at a certain age, animals affected with BLAD are able to cope with environmental agents due to compensatory mechanisms of the immune system.

Anemia↗

Bovine leukocyte adhesion deficiency--clinical course and laboratory findings in eight affected animals.

The clinical course of Bovine Leukocyte Adhesion Deficiency (BLAD) in eight Holstein Friesian cattle is described. Affected animals were presented with a history of poor thriving and recurrent bacterial infections. Five of these animals had to be killed because of severe respiratory disease shortly after admittance. Three affected animals survived calfhood only as a result of frequent antibacterial treatments. At one year of age, failure to thrive and stunted growth were still evident, but infections requiring antibiotic treatments occurred only sporadically. Clinical manifestations of BLAD were found in the digestive system (gingivitis, periodontitis, alveolar periostitis, diarrhoea), the respiratory system and the skin (impaired wound healing, chronic dermatitis). A leukocytosis based on a mature neutrophilia, which persisted during infection-free periods, was observed in all animals. Granulocytes were substantially deficient of beta 2-integrin expression on their membranes. Anaemia, which was noted in four animals, may be related to the Anaemia of Inflammatory Disease Complex (AID). The serum total protein content increased with time and was associated with elevated gamma-globulin levels. We suggest that, at a certain age, animals affected with BLAD are able to cope with environmental agents due to compensatory mechanisms of the immune system.

Animals↗

Dysfunction of monocytes and dendritic cells in patients with premature ovarian failure.

PROBLEM: Due to the presence of ovarian antibodies it has been suggested that premature ovarian failure (POF) belongs to the autoimmune endocrinopathies. Monocytes and the monocyte-derived dendritic cells play a prominent role in the initial stages of endocrine autoimmune reactions: the accumulation of monocytes/dendritic cells and the clustering of dendritic cells in endocrine organs is one of the first phenomena of an autoimmune endocrinopathy. METHOD: This report describes a study on (1) the chemotactic responsiveness of blood monocytes, and (2) the cluster capability of blood dendritic cells in POF patients. The monocyte chemotaxis was determined using the cell's capability to polarize (changes in shape determined by light microscopy) under the influence of the chemoattractant, N-formyl-methionyl-leucyl-phenylalanine (fMLP). The cluster capability of dendritic cells was tested by allowing the dendritic cells to form aggregates with allogenic lymphocytes in vitro. RESULTS: The blood monocytes of 46% of a total of 28 POF patients showed a decreased fMLP induced monocyte polarization in comparison to healthy control values. None of the young female controls (N = 28) and postmenopausal women (N = 17), showed such a defective monocyte polarization. The blood dendritic cells of 36% of the POF patients showed a decreased cluster capability. Defects in monocyte polarization and dendritic cell clustering were not affected by therapies aimed at changes in the estrogen levels or gonadotropin levels of the patients [using estrogen substitution therapy, gonadotropin-releasing hormone (GnRH) analog, follicle-stimulating hormone (FSH)]. CONCLUSIONS: A redistribution of active monocytes and of active dendritic cells from the peripheral blood to the ovaries may be the cause of the described abnormalities. Since similar abnormalities in monocyte function and dendritic cell function have been described in Graves' disease and type I diabetes, the data strengthen the view that POF is one of the endocrine autoimmune diseases.

Adult↗

A human CD5+ B cell clone that secretes an idiotype-specific high affinity IgM monoclonal antibody.

We previously demonstrated the occurrence of a naturally arisen human anti-idiotypic B cell clone, that we transformed with EBV (EBV383). We show evidence that EBV383 not only expresses the CD5 surface Ag, but also contains the 2.7-kb mRNA transcript encoding this protein. In addition, we show the presence of the 3.6-kb mRNA precursor. Most Ig produced by CD5+ B cells are polyreactive natural IgM antibodies encoded by unmutated copies of germline VH genes. However, in this study we present data demonstrating the monoreactive high affinity character of the anti-idiotypic antibody (mAb383) produced by EBV383. These data are in agreement with our previous observations, showing that the VH chain of mAb383 is encoded by an extensive somatically mutated VHV gene in a way that is consistent with an Ag-driven immune response. A possible role for this remarkable anti-idiotypic antibody in the maintenance of B cell memory is discussed.

Antibodies, Anti-Idiotypic↗

Evidence for existence of immunoglobulins that block ovarian granulosa cell growth in vitro. A putative role in resistant ovary syndrome?

The sera of 26 patients with premature ovarian failure were examined in order to detect immunoglobulin-G (IgGs) that can block FSH-induced in vitro granulosa cell DNA synthesis via, a Feulgen cytochemical bioassay system. The IgGs of four patients with polycystic ovary-like disease, five postmenopausal women, and four eumenorrheic women served as controls. Ovarian growth blocking IgGs were found in 21 of the 26 premature ovarian failure (POF) cases. The few cases characterized by the absence of follicles (streak ovaries) and the controls were negative. The ovarian blocking IgGs were far more prevalent in the POF cases than anti-cytoplasmic ovarian antibodies detected by an indirect immunofluorescence assay (only one of the 26 POF patients was positive). Our data hence confirm earlier expressed views that immune mechanisms are involved in a high proportion of patients with POF.

Adult↗