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Biomedical subjects

J F Sluiters

Publications and source records attributed to J F Sluiters.

At least 19 recordsLinked to original sources
PubMed2003

Cryptosporidium parvum and Isospora belli infections among patients with and without diarrhoea.

OBJECTIVE: To assess the importance of Cryptosporidium parvum and Isospora belli infections as a cause of diarrhoea among patients admitted to the Medical Wards in Queen Elizabeth Central Hospital (QECH) in Blantyre, Malawi. DESIGN: Prospective case control study. SUBJECTS: One hundred and twenty one patients with diarrhoea and 122 patients without diarrhoea. MAIN OUTCOME MEASURES: Demonstration of C. parvum and I. belli oocysts by examination of at least one stool sample per patient using phenol auramine-O-fluorescence staining and an immuno-fluorescent assay with monoclonal antibodies against Cryptosporidium, seropositivity for HIV and AIDS. RESULTS: In 22% of the patients with diarrhoea an infection with C. parvum or I. belli was found. Thirteen (11%) of them had a C. parvum and 14 (12%) an I. belli infection; a mixed infection was found in one patient. In the control group, three (3%) C. parvum and three (3%) I. belli infections were seen. The prevalence of both infections was very significantly higher in the cohort of diarrhoea patients than in the controls, 13/108 versus 3/119 (p=0.0099) for C. parvum, and 14/107 versus 3/119 (p=0.0056) for I. belli. Infections were only seen in HIV positive patients. Two hundred and four (84%) patients were HIV positive and 145 (60%) of them had AIDS. CONCLUSIONS: C. parvum and I. belli infections are a significant cause of diarrhoea among medical in-patients at QECH. Examinations of stool specimen for parasites among hospitalised patients with diarrhoea provide data for a more appropriate management.

AIDS-Related Opportunistic Infections↗
PubMed2001

Pseudoparasitic pneumonia after bone marrow transplantation.

We present a female patient from Somalia with an acute lymphoblastic leukemia, who received an allogeneic bone marrow transplantation (BMT) and developed several periods of moderate to severe pulmonary symptoms that were accompanied by pulmonary infiltrates and peripheral blood eosinophilia. After several recurrences an open lung biopsy was performed, which initially gave rise to the diagnosis parasitic infection. Later on this diagnosis was questioned and it was suggested that the structures were artifacts that might have been aspirated. Nevertheless, after the immediately given antihelminthic treatment no peripheral blood eosinophilia occurred anymore, but at that point of time pulmonary function was already severely hampered and eventually led to a lethal complication. With the worldwide increasing migration from Third World countries with a high prevalence of parasitic infections, more patients will receive immunosuppressive therapies in countries less familiar with parasites. This may complicate diagnostic procedures, prevent early recognition and delay adequate treatment. Specific screening for opportunistic parasitic infections of the population at risk before BMT and a great awareness for these infections is strongly recommended.

Adolescent↗
PubMed1992

Improvement of pulmonary gas exchange after surfactant replacement in rats with Pneumocystis carinii pneumonia.

The effect of intratracheal surfactant instillation on pulmonary function in rats with pneumocystis carinii pneumonia (PCP) was investigated. In these animals which developed PCP with severe respiratory failure after s.c. administration of cortisone acetate over 8-12 weeks, pulmonary function could be improved by surfactant instillation, as measured by an increase in PaO2. Histological examination showed that alveoli of rats with PCP which received no surfactant treatment are filled with foamy edema, whereas after surfactant treatment alveoli are stabilized and well-aerated. These results indicate that surfactant therapy could be used in patients with severe PCP to overcome an acute stage of respiratory distress while at the same time surfactant could serve as a carrier substance for antimicrobial drugs to attain high intra-alveolar and low systemic antimicrobial drug concentrations.

Animals↗
PubMed1991

[Pneumocystis carinii pneumonia in patients with a severe combined immunodeficiency].

We describe three patients with Pneumocystis carinii pneumonia as the initial presentation of severe combined immunodeficiency disease. The pneumonia in the first patient was treated successfully with trimethoprim/sulphamethoxazole (Tmp/Smz). The second patient died despite therapy with Tmp/Smz and pentamidine. The third patient failed to respond to therapy with Tmp/Smz and pentamidine. He was subsequently treated with trimetrexate and leucovorin. Treatment with the new folic acid antagonist trimetrexate resulted in complete recovery. The case histories of these children serve to illustrate the clinical symptoms and new therapeutic modalities of P. carinii pneumonia in patients with immunodeficiency disease.

Humans↗
PubMed1991

Effect of surfactant replacement on Pneumocystis carinii pneumonia in rats.

The effect of intratracheal surfactant instillation on pulmonary function in rats with Pneumocystis carinii pneumonia (PCP) was investigated. In those animals which developed PCP with severe respiratory failure after administration of cortisone acetate s.c. over 8-12 weeks, pulmonary function was improved by surfactant instillation. PaO2 values 30 min after surfactant instillation were significantly higher compared to pretreatment values and also compared to PaO2 values of rats 30 min after receiving saline (482.9 mmHg +/- 44.7, 170.7 mmHg +/- 39.3 and 67.2 mmHg +/- 17.4, respectively). Histological examination showed that alveoli of rats with PCP which received no exogenous surfactant are filled with foamy edema, whereas after exogenous surfactant alveoli are stabilized and well-aerated. These results indicate that exogenous surfactant may help patients with severe PCP to overcome an acute stage of respiratory distress.

Animals↗
PubMed1989

Indirect enzyme-linked immunosorbent assay for immunoglobulin G and four immunoassays for immunoglobulin M to Toxoplasma gondii in a series of heart transplant recipients.

Toxoplasma gondii infections in heart transplant recipients were monitored by indirect enzyme-linked immunosorbent assay for immunoglobulin G (ELISA-IgG), indirect ELISA-IgM in serum IgM fractions, antibody capture ELISA-IgM, IgM-immunosorbent agglutination assay (ISAGA), and IgM immunoblotting. Basic immunosuppression consisted of cyclosporine and low-dose steroids. Before transplantation, 26 of 43 recipients showed serological evidence of infection. In serum samples from 15 (35%) recipients, specific antibodies were not detected. Approximately 50% of the heart donors, were toxoplasma seropositive. Eight of the fifteen seronegative recipients received hearts from toxoplasma-seropositive donors. In four of the eight recipients, seroconversion could be demonstrated with all tests used. In three of these four patients, clinical disease developed. One patient with strong serological evidence of toxoplasmosis died, but toxoplasma parasites and antigens were not detected at autopsy. In two patients, toxoplasma cysts were found in cardiac biopsies. Seroconversion was not prevented by the use of spiramycin prophylaxis in two recipients. Reactivations of latent infections or reinfections were detected by indirect ELISA in six (23%) seropositive recipients, but symptoms and signs of active T. gondii infection were not seen. Seroconversion and reactivation of infection were readily found by a combined use of indirect ELISA-IgG and ELISA-IgM and antibody capture ELISA-IgM. Discrepancies in results could be examined by immunoblotting. IgM-ISAGA retained stable positive values longer than IgM-ELISAs did. Cyclosporine treatment did not hamper detection of seroconversion but could cause antibody levels to remain relatively low in primary infections. Seronegative recipients should receive antitoxoplasma treatment on seroconversion.

Agglutination Tests↗
PubMed1987

Ookinete antigens of Plasmodium berghei: a light and electron-microscope immunogold study of expression of the 21 kDa determinant recognized by a transmission-blocking antibody.

The expression of a 21 kDa transmission-blocking determinant on the malarial parasite Plasmodium berghei was studied by using the immunogold method at the light, scanning-electron and transmission-electron microscope levels. The determinant was shown to be expressed exclusively on the macrogamete and its immediate progeny the zygote, ookinete and oocyst. It is first detected on the plasmalemma two hours after the escape of the parasite from the red blood cell, reaches a maximal density on the young ookinete some ten hours later, and is still found on the oocyst after six days. The antigen is distributed evenly over the entire surface of the zygote and ookinete, but is readily shed from the parasite surface. The general applicability of the silver-enhanced immunogold method in parasitological research is emphasized.

Animals↗
PubMed1987

Allozyme variation in Anopheles stephensi Liston from Pakistan (Diptera: Culicidae).

Allozyme variability was analyzed at 16 loci in 11 lines of Anopheles stephensi Liston from Pakistan. Six lines were considered as samples from natural populations. For these lines the mean number of alleles was 1.31-1.63, the degree of polymorphism was 0.188-0.375, the observed heterozygosity was 0.065-0.086, and the genetic distance ranged from 0.001 to 0.016. No population-specific alleles were found. Interbreeding was considerable (mean Fit = 0.183). Differences in allele frequencies were due considerable (mean Fit = 0.183). Differences in allele frequencies were due primarily to local inbreeding (Fis greater than Fst at most loci). The Lahore line, reared for more than 20 generations, had more homozygotes than the other lines. A line refractory to Plasmodium falciparum and a genetic sexing line exhibited decreased allozyme variability. The latter line showed reduced staining intensity at 10 loci. Linkage studies are recommended for the following loci with rare alleles: Acp, Gapdh, Icd-1, Icd-2, Mpi, and Pgd.

Alleles↗
PubMed1986

The establishment of Plasmodium berghei in mosquitoes of a refractory and a susceptible line of Anopheles atroparvus.

The events between the ingestion of Plasmodium berghei-infected mouse blood and the establishment of the ookinetes in the epithelium of the midgut in refractory (R) and susceptible (S) Anopheles atroparvus are described. Simultaneously fed, fully engorged female mosquitoes were randomly assigned to dissection at 22, 28, 32, 48 h and 10 days (controls) after the infective feed (post-infection: p.i.). Serial transverse sections of 6 micron were cut. Every 10th section was studied. The maturation of ookinetes was monitored at 16, 19 and 22 h p.i. The infections in R and S mosquitoes developed similarly with regard to the maturation of ookinetes and the number of mature ookinetes in the lumen of the midgut. The semiquantitative evaluation of the envelopment of the food bolus by the peritrophic layer showed that this layer cannot function as a physical barrier against migrating ookinetes. In the midgut epithelium the number of ookinetes decreased significantly with time in both R and S mosquitoes, but a similar number of penetrations was recorded for both types of mosquito. In S mosquitoes maximal 1% of the ookinetes present in the midgut formed an oocyst. In both R and S mosquitoes a substantial loss of parasites was found, first in the lumen of the midgut and second after penetration of the midgut epithelium by the mature ookinetes. Relatively few parasites develop into oocysts in S, but hardly any do so in R individuals. The factors in control of refractoriness are likely to operate on early oocyst development.

Animals↗
PubMed1984

Increased activity of the female gonadotropic hormone producing dorsal bodies in Lymnaea stagnalis infected with Trichobilharzia ocellata.

Juvenile specimens of Lymnaea stagnalis were exposed to 0 or 4 miracidia of Trichobilharzia ocellata. Dissection followed at day 22 post exposure. The effects of infection on the activity of the female gonadotropic hormone producing Dorsal Bodies (DB) were studied by phase-contrast and electron microscopy. Morphometry shows that the relative volume of DB cells of infected snails is 1.6 times as high as in controls. This is mainly due to a 45% higher cytoplasmic volume. The number of profiles of the Golgi apparatus increases by nearly 90% and the Golgi volume by 40% as a result of infection. Numerous omega-shaped indentations of the plasma membrane of the DB cell processes indicate the release of the contents of the DB hormone containing elementary granules. It is concluded that parasitic infection causes a clear increase in the synthetic activity of the DB. Most probably, the parasites exert the inhibiting effects on reproductive activity at the level of the targets of the reproductive hormones.

Animals↗
PubMed1981

Development of Trichobilharzia ocellata in Lymnaea stagnalis and the effects of infection on the reproductive system of the host.

Juvenile specimens of Lymnaea stagnalis were exposed to 0 or 4 miracidia of Trichobilharzia ocellata. Highly productive infections developed in all infected snails. Qualitative and/or quantitative light microscopic observations were performed at various intervals between day 0 and 83 post exposure (p.e.). Gonadal maturation started between day 4 and 7 p.e. in all snails, but in infected animals gonadal growth was retarded considerably after day 7 and was blocked from day 19 onwards. This resulted in very small gonads (10% of the volumes of those of controls on day 83 p.e.) in infected snails, in which however, gametogenesis was initially normal. Due to the small gonad volume gamete production was highly reduced. From day 33 onwards spermatogenesis appeared to be inhibited and around day 83 oocyte maturation seemed to be impaired. The accessory sex organs (ASO) of infected snails showed a similar reduced growth. The cellular differentiation and production of secretory granules in these small ASO was normal albeit delayed in both the male and female organs. The severe reduction in growth of the gonad and the ASO started in the presence of immature primary sporocysts, the later effects on gametogenesis were simultaneous with the production of massive numbers of cercariae. These results are discussed in view of the available data on the endocrine control or reproduction in L. stagnalis. It is suggested that either the secretion of gonadotrophic hormones or the response of their targets is reduced by humoral effects of the parasites.

Animals↗
PubMed1980

The relationship between miracidial dose, production of cercariae, and reproductive activity of the host in the combination Trichobilharzia ocellata and Lymnaea stagnalis.

The effects of exposure of juvenile Lymnaea stagnalis to one, two or, four miracidia of Trichobilharzia ocellata on the following parameters were studied: infection rate, length of prepatent period, production of cercariae, growth and ovipository activity of the snails, and the weights of their accessory sex organs. An infection rate of 100% was established with all miracidial doses. Morality of the snails was low in all experimental groups. In cercarial production high-(HP) and low-productive (LP) infections could be distinguished. An increase in miracidial dose at exposure results in an increase in the number of snails with HP-infections and decreases the length of the prepatent period of these infections. Snails with HP-infections grow faster than controls after day 14 post-exposure and show giant growth, while the accessory sex organs remain very small. The snails show hardly any ovipository activity. In all snails with HP-infections these effects are observed independent of the miracidial dose at exposure. Snails with LP-infections demonstrate no signs of gigantism, their accessory sex organs are almost identical to those of controls, and the snails show ovipository activity. It is concluded that the occurrence of HP- and LP-infections indicates differences in reproductive capacity of the parasite. HP-infections can only develop when the parasites can adjust the host to their requirements at an early stage of the infection.

Animals↗