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Biomedical subjects

J de Groot

Publications and source records attributed to J de Groot.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Heart diseases in foals. A literature review exemplified by 2 case reports].

A review of the congenital and acquired heart diseases of foals is given on the basis of two patients. A 3-month-old foal with a history of collapse after exercise had a systolic murmur on all heart valves on both sides. Necropsy revealed endocarditis ulcerosa of the left atrioventricular valves. A 6-week-old foal with systolic murmur on the left atrioventricular valves and on the aorta showed, on ultrasonography, signs of endocarditis of the atrioventricular valves. This foal recovered after a long course of antibiotics.

Animals↗
PubMed1994

[Little difference in quality of life of dialysis patients in Utrecht and Willemstad].

OBJECTIVE: To assess and compare the quality of life of patients treated with haemodialysis and chronic ambulatory peritoneal dialysis (CAPD) in Utrecht and Willemstad, Curaçao. DESIGN: Transverse multicentre study. METHODS: All haemodialysis and CAPD patients in Utrecht and all haemodialysis patients in Curaçao under treatment for over 6 months were studied. The objective tests applied were the 'Nottingham health profile', the 'affect balance scale', the 'index of well-being' and the 'Amsterdam complaint profile'. Possible correlations between individual patient-related and treatment-related factors and biochemical variables were also investigated. RESULTS: The objective and subjective tests revealed only slight differences in quality of life in the three groups. In a few respects, the CAPD patients rated the quality of life slightly better. In the Utrecht group a positive relationship was seen between haematocrit (higher owing to treatment with erythropoietin) and plasma bicarbonate concentration, and the quality of life.

Cross-Cultural Comparison↗
PubMed1994

The risk of sensibilization and contact urticaria upon topical application of fumaric acid derivatives.

Systemic and sometimes topical therapy with fumaric acid (FA) and its derivatives is used in the treatment of psoriasis. Scattered data show that the topical application of these derivatives elicits side effects. Application of FA and some derivatives on the skin was accompanied by perilesional skin irritation, macular papular rashes and urticarial reactions. In order to determine the irritating and sensitizing properties of FA derivatives we used a cytotoxicity, flank irritation, ear swelling and guinea pig maximization test. The results of the cytotoxicity test demonstrated that dimethylfumarate (DMF) was the most toxic derivative. DMF induced also contact-urticarial reactions in contrast to mono-ethylfumarate (MEF). Challenge experiments with FA, MEF and DMF in MEF- and DMF-sensitized guinea pigs demonstrated that both MEF and DMF are moderate contact sensitizers. In DMF-sensitized animals cross-reactions with MEF were found. As DMF and MEF have cytotoxic, contact-urticarial and/or sensitizing properties, topical application should be avoided.

Administration, Topical↗
PubMed1992

Development of a concomitant nickel and chromium sensitization model in the guinea pig.

Although nickel allergy is the most frequent contact hypersensitivity in man, reports on successful nickel sensitization in experimental animals are scarce. Chromium hypersensitivity, on the other hand, is readily induced in guinea pigs. In this study we set out to obtain reproducible nickel sensitization in guinea pigs, in order to establish an animal model for immunospecific tolerance and desensitization studies in which two non-cross-reacting metal allergens, chromium and nickel, could be studied simultaneously. Strong and reproducible sensitization to nickel was achieved by injecting low amounts of Freund's complete adjuvant and nickel sulfate in a split-adjuvant procedure. Strong erythematous reactions were observed as early as 14 days after sensitization and could be elicited both by intradermal and open epicutaneous challenges. Optimal evaluation was with nickel sulfate administered epicutaneously in 40% dimethyl sulfoxide to enhance skin penetration. Hypersensitivity could be transferred with lymphocytes and not with serum. Sensitization procedures for nickel and chromium then could successfully be combined in a double sensitization procedure. With four different guinea pig strains no genetic restriction was observed for the induction of nickel or chromium sensitivity. However, for both metals a clear sex and age dependence was observed: female guinea pigs reached a higher degree of sensitization than males, whereas sensitization in young animals was relatively weak.

Administration, Cutaneous↗
PubMed1991

Cardiogenic shock after acute myocardial infarction. Incidence and mortality from a community-wide perspective, 1975 to 1988.

BACKGROUND: Cardiogenic shock resulting from acute myocardial infarction is a serious complication with a high mortality rate, but little is known about whether its incidence or outcome has changed over time. As part of an ongoing population-based study of acute myocardial infarction, we examined trends over time in the incidence and mortality rate of cardiogenic shock after acute myocardial infarction. METHODS: We studied 4762 patients with acute myocardial infarction who were admitted to 16 hospitals in the Worcester, Massachusetts, metropolitan area between 1975 and 1988. We determined the incidence of and short-term and long-term mortality due to cardiogenic shock in each of six years during this study period. RESULTS: The incidence of cardiogenic shock complicating acute myocardial infarction remained relatively constant, averaging 7.5 percent. Multivariate regression analysis that controlled for variables affecting incidence revealed significant though inconsistent temporal trends in the incidence of cardiogenic shock. As compared with the risk in 1975, the adjusted relative risk (with 95 percent confidence interval) was 0.83 (0.54 to 1.28) in 1978, 0.96 (0.63 to 1.48) in 1981, 0.68 (0.42 to 1.12) in 1984, 1.16 (0.70 to 1.92) in 1986, and 1.65 (0.99 to 2.77) in 1988. The overall in-hospital mortality rate among patients with cardiogenic shock was significantly higher than that among patients without this complication (77.7 percent vs. 13.5 percent, P less than 0.001). The in-hospital mortality among the patients with shock did not improve between 1975 (73.7 percent) and 1988 (81.7 percent). Long-term survival during the 14-year follow-up period was significantly worse among patients who survived cardiogenic shock during hospitalization than among patients who did not have shock (P less than 0.001). CONCLUSIONS: The results of this observational, community-wide study suggest that neither the incidence nor the prognosis of cardiogenic shock resulting from acute myocardial infarction has improved over time. Both in-hospital and long-term survival remain poor for patients with this complication.

Aged↗
PubMed1991

Proliferative capacity of mononuclear cells in the human lung.

In pulmonary sarcoidosis, a chronic granulomatous disorder with different stages of activity, the proliferative capacity of the alveolar mononuclear cells is unknown. To get a closer look at this proliferation we combined pulse labeling (by means of tritium thymidine incorporation and autoradiography) with an immunocytochemical staining assay. This assay revealed on one single slide simultaneously blue CD4+ lymphocytes, brown CD8+ lymphocytes and red macrophages. We were able to show that CD4+ as well as CD8+ lymphocytes were radiolabeled only in the active state of the disease. But macrophage proliferation occurred independently of the activity of the disease. In other words with this combination of techniques, it is possible to differentiate, on a single slide, three subsets of mononuclear cells, in combination with their proliferative behavior.

Autoradiography↗
PubMed1991

[Equine monocytic ehrlichiosis (EME), a review].

Serological surveys showed that equine monocytic ehrlichiosis (EME) occurs in the USA, Canada and Europe. The causative agent is Rickettsia Ehrlichia risticii, isolated for the first time in 1984. The clinical features of the disease are sluggishness, anorexia, colic and fever, possibly followed by watery diarrhoea. Complications of an infection with E. risticii are laminitis and abortion. Colitis of the ascending colon may be observed at autopsy. Following a positive serological diagnosis (IgM ELISA) of EME, treatment with oxytetracycline can be initiated. It is also important to restore the fluid and electrolyte balance by infusion. Prevention may be achieved by vaccination.

Animals↗
PubMed1991

A comparison of adinazolam and desipramine in the treatment of major depression.

Thirty-one patients with a DSM-III (R) diagnosis of Major Depression received adinazolam (n = 16) or desipramine (n = 15) during a 6 week double-blind randomized controlled trial. Both groups showed a significant decline in Hamilton Rating Scale for Depression scores (21.8 +/- 4.5 to 10.7 +/- 8.5 for adinazolam and 23.5 +/- 5.5 to 12.9 +/- 8.6) for desipramine. Melancholic and anxiety symptoms were reduced equally by both drugs. Initial sedation was the most common side-effect with adinazolam. Plasma levels of desipramine and hydroxy-desipramine correlated highly with oral dose after 3 weeks of treatment.

Adult↗
PubMed1991

Macrophage-T suppressor cell interference in the lungs of steroid-treated sarcoidosis patients.

In the bronchoalveolar lavage of sarcoidosis patients the mononuclear cell infiltrate was enumerated on T helper and suppressor lymphocytes as well as macrophages by means of a triple-staining assay on cytospin slides. As was seen on the slides, lymphocytes were often adhered very closely to macrophages. This phenomenon, many times described but not understood, was studied in a group of 13 sarcoidosis patients, of whom 7 received prednisolone treatment. It could be shown that treatment with the corticosteroid was followed by an increase in the percentage of suppressor lymphocytes adhered to macrophages. Second, the number of such alveolar T suppressor lymphocyte-macrophage aggregates was dramatically increased in the prednisolone-treated patients.

Adult↗
PubMed1990

Low allergenicity of clonidine impedes studies of sensitization mechanisms in guinea pig models.

During clinical trials, a clonidine transdermal device has been found to induce clonidine-specific allergic contact dermatitis in up to 25% of patients during a treatment period of 1 year. Using 3 different guinea pig strains, development was attempted of an experimental guinea pig model that would allow for in-depth studies into the mechanism of sensitization, and a possible role of transdermal device components. Transient low-level clonidine allergy could be obtained only in a minority of animals, with severe sensitization procedures departing from epicutaneous applications, combined with intradermal (adjuvant) FCA injections. Sensitization was not potentiated by additional booster procedures, including cyclophosphamide pretreatment, nor any of the putative cofactors (UV-treatments, C. parvum or acetaldehyde involvement) studied. These results suggest that the persistent skin contacts in man, with transdermal devices for sustained drug delivery, generate unique conditions favouring the development of allergic contact dermatitis, which are difficult to mimic in experimental animal models. Thus, clinical allergy may develop even to extremely weak sensitizing drugs that can be safely used orally, and escape most currently available predictive contact allergy animal models. Clinical studies remain unavoidable for studying factors that may reduce sensitization rates to more acceptable levels.

Administration, Cutaneous↗
PubMed1989

Histochemical characterization and functional significance of the hyperintense signal on MR images of the posterior pituitary.

MR imaging of the pituitary fossa characteristically shows a well-circumscribed area of high signal intensity in the posterior lobe on T1-weighted images. We used a combination of high-field MR, electron microscopy, and histologic techniques in experimental animals to determine whether the hyperintensity of the posterior lobe might be functionally related to hormone neurosecretory processes, and to attempt to establish its chemical nature. Histologic sections of a dog's pituitary gland processed with lipid-specific markers showed intense staining in the posterior lobe but not in the anterior lobe, thus documenting the location of fat in the posterior pituitary. Administration of vasoactive drugs known to influence vasopressin secretion to anesthetized cats produced changes in the volume of high-intensity signal in the posterior pituitary. Subsequent electron microscopy showed a significant increase in posterior lobe glial cell lipid droplets and neurosecretory granules in dehydration-stimulated cats. The data suggest that the pituitary hyperintensity represents intracellular lipid signal in the glial cell pituicytes of the posterior lobe or neurosecretory granules containing vasopressin. The volume of the signal may, in turn, reflect the functional state of hormonal release from the neurohypophysis.

Animals↗
PubMed1988

Suppressive effects of transdermal clonidine administration on contact hypersensitivity reactions in guinea pigs.

In the present study, immunopharmacological effects of clonidine-TTS on allergic contact dermatitis (ACD) to non-related, established contact sensitizers were investigated in guinea pigs. First, to evaluate the hypotensive effect of clonidine-TTS in guinea pigs, intra-arterial blood pressure was recorded. After 4 days of treatment with one (or two) TTS per animal, a reduction of arterial blood pressure from 71 +/- 1 to 51 +/- 2 mm Hg was observed. We subsequently assessed the effects of clonidine-TTS on contact hypersensitivity reactions to 2,4-dinitrochlorobenzene (DNCB) and 4-ethoxymethylene-2-phenyl-oxazolone (Ox). This study indicates that clonidine-TTS suppressed the elicitation of contact hypersensitivity reactions. The observed immunosuppressive effect of clonidine may account for the relatively weak hypersensitivity reactions to this drug in experimental animal studies. Further studies are needed to determine whether such findings are of relevance to the clinical use of clonidine in patient populations.

Administration, Cutaneous↗
PubMed1987

Posterior pituitary gland: appearance on MR images in normal and pathologic states.

T1-weighted magnetic resonance (MR) images of the pituitary gland and sella turcica routinely demonstrate a region of high signal intensity in the neurohypophysis. High-resolution MR imaging studies of the sella turcica in 200 subjects with a normal or abnormal sella were analyzed. The hyperintensity was found in the images of about 90% of healthy subjects and patients with microadenoma, in only 43% of patients with macroadenoma, and in 12% of patients with empty sellae. The signal was absent in several patients with functional or anatomic abnormalities of the hypothalamic-hypophyseal axis. It is concluded that the high signal intensity in the posterior lobe of the pituitary gland is present in most healthy individuals and that its absence in many patients with large intrasellar masses and empty sellae is due to compression of posterior lobe tissue. Its absence in diabetes insipidus further suggests a relationship between hyperintensity and the functional status of the hypothalamic-hypophyseal axis.

Adenoma↗
PubMed1986

Intradermal administration of 4-hydroperoxy-cyclophosphamide during contact sensitization potentiates effector T cell responsiveness in draining lymph nodes.

4-Hydroperoxy-cyclophosphamide (4-HPCY) is an in vitro active form of cyclophosphamide. In a previous study, using an in vivo contact sensitivity model in the guinea pig, we demonstrated that intradermal injection of small amounts (50-200 micrograms) of 4-HPCY at the sensitization site resulted in strong potentiation of contact hypersensitivity (Boerrigter and Scheper, 1984). It was postulated that 4-HPCY induces a local decrease of feedback control within the draining antigenically stimulated lymph nodes. The present data are in support of this view: Lymph node hyperplasia induced by contact sensitization (to dinitrochlorobenzene or oxazolone) was further enhanced by 4-HPCY treatment. The paracortical area was preferentially enlarged. 4-HPCY-treated lymph nodes showed an augmentation of hapten-specific T effector cell function as determined in transfer experiments. The response of such lymph node-derived cells to the T cell mitogen PHA was enhanced. Although 4-HPCY treatment resulted simultaneously in a decrease in responsiveness of draining lymph node-derived cells to the B cell mitogen lipopolysaccharide, anti-hapten antibody production was not affected. The present study demonstrates that important similarities exist between the effects of local 4-HPCY treatment and systemic cyclophosphamide pretreatment on the immune response. As systemic treatment with a high dose of cyclophosphamide is known to have serious side effects, the present local protocol provides a new attractive and versatile strategy for T cell immunopotentiation.

Animals↗
PubMed1986

Radionuclides in detecting active granuloma formation. Gallium-67 scintigraphy and histopathology with autoradiographic findings.

Granuloma formation studies were performed on lungs of guinea pigs sensitized with FCA over 2 to 17 months. Prolonged time of sensitization revealed more granulomatous pulmonary tissue. An intravenous booster of FCA in the animals that had been sensitized for 3 months yielded enhanced granuloma formation within 5 days. The histopathology of these lungs was comparable with that seen in lungs of animals after 17 months of sensitization without booster. Enhanced local proliferation of macrophages, measured by [3H]thymidine incorporation and autoradiography, was seen in the lungs of the animals that had received boosters. Moreover, 67Ga scintigraphy was strongly positive in these animals. Scintigraphy of cell suspensions of pulmonary tissue from these animals showed that 67Ga was predominantly taken up (quantitatively as well as qualitatively) by the alveolar macrophages. Cell suspensions of sarcoidosis patients, prepared in the same way, showed only a low level of 67Ga uptake, one comparable to that of the pulmonary cell suspensions of the sensitized animals that had not received boosters. It is suggested that a negative scintigraphy in patients with chronic pulmonary granulomatous disorders could be (partly) explained by the absence of activated macrophages.

Animals↗
PubMed1984

Evaluation of various cytostatic drugs as local immunotherapeutic agents.

The cytostatic drugs methotrexate, 5-fluorouracil, adriamycin, vincristin, cisplatinum, VP-16 and the newly synthesized, stabile cyclophosphamide-derivative Z-7557, were screened for possible immunopotentiating effects in local chemotherapy. With an in vivo contact sensitivity model in guinea pigs, low dosages of the drugs were introduced into antigenically stimulated lymph nodes by intradermal injections following sensitization. Marked till strong potentiation of T-cell function, as measured by the development of contact hypersensitivity, was observed with all drugs tested, except for methotrexate and 5-fluorouracil. With a similar local chemotherapeutic protocol in the guinea pig line 10 hepatocellular carcinoma-model, these latter drugs have been reported earlier to be exceptional in failing to induce tumor regression and tumor immunity. Our present results suggest that local chemotherapy of malignancies not only may reduce local tumor load, but also may affect distant metastases by facilitating the development of tumor-specific immunity.

Adjuvants, Immunologic↗
PubMed1983

Comparative migration of T- and B-lymphocyte subpopulations into skin inflammatory sites.

Homing of 51Cr-labelled spleen and lymph node-derived T- and B-cell subpopulations into inflammatory sites in the skin, as well as into lymphoid and non-lymphoid organs, was studied in outbred and inbred guinea-pigs. The early progeny of activated T cells were demonstrated in immunologically-mediated inflammation of the skin, for example a cell-mediated immune reaction and a reversed passive Arthus reaction. In contrast, spleen and lymph node-derived B cells were virtually unable to enter inflammatory sites. Organ-specific homing of T and B cells was detected. The significance of these observations for the interpretation of results of lymphoid cell transfers in guinea-pigs is discussed.

Animals↗