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Biomedical subjects

K Pfister

Publications and source records attributed to K Pfister.

At least 91 records · Page 5Linked to original sources
PubMed1984

Partial purification of somatic and excretory-secretory products of adult Fasciola hepatica and their application for the serodiagnosis of experimental and natural fascioliasis using an ELISA.

Six partially purified antigen fractions from adult Fasciola hepatica (three somatic tissues [Fhs] and three excretory products [Fhm]) were used in a micro-ELISA to monitor the serum antibody levels of an experimental rabbit F hepatica infection. Fhs 1 detected infection after 19 to 26 days and the titre remained significantly higher than that of the controls until day 103 of infection (end of experiment). Using Fhm 1 and Fhm 2, antibodies were detected between 12 and 19 days after infection. Fhm 2 distinguished infected from uninfected rabbits during the entire experimental period, whereas Fhm 1 did not. Excretory-secretory products of a low molecular weight were also antigenic and could differentiate between infected animals and controls. One hundred and nine sera from naturally infected cattle and uninfected controls were tested with the same antigens. Although antibody was detected, the results were inconsistent and further purification of the antigens may eventually improve the sensitivity of the method.

Animals↗
PubMed1984

Local antibody responses in the bile and faeces of sheep infected with Fasciola hepatica.

The effect of infection with the liver fluke Fasciola hepatica on serum, bile and faecal immunoglobulin and antibody levels was studied in Scottish Blackface sheep. In the serum the immunoglobulins showing the most marked increase were IgG1 and IgG2 and their maximal values were reached at 16 weeks after infection. In the bile IgG2 rose to peak values at two weeks and IgG1, IgA and IgM were maximal at four weeks after infection. The levels of faecal IgG and IgA were low after primary infection but after reinfection a rapid increase in IgA concentration was observed within one to two weeks. Haemagglutinating antibody levels against egg antigens, juvenile and adult excretory-secretory antigens and adult fluke somatic antigens were evaluated. In the sera high titres were observed starting from two to four weeks after infection and persisting until 14 to 16 weeks. Bile haemagglutinating antibodies against excretory-secretory antigens showed the highest level at two and four weeks after infection while antibodies against adult somatic antigens reached maximal titres between four and eight weeks. Faecal antibody levels after primary infection were low but increased rapidly within two weeks after reinfection, coinciding with the elevation in faecal IgA concentration. However, there was no reduction in the number of flukes established in reinfected animals.

Animals↗
PubMed1984

Presence and absence of the microsomal beta-glucuronidase in mice correlates with differences in the processing of the lysosomal enzyme.

In some tissues such as liver and kidney, beta-glucuronidase is present not only in the lysosomes but also in the microsomes. Both enzymes are coded by the same structural gene. The function of the microsomal enzyme is still unclear. We have observed in primary cultures of mouse hepatocytes that the microsomal enzyme disappeared to a trace within 5 days after plating cells. This change of intracellular localization coincided with a change of the isoelectric focusing pattern of the lysosomal beta-glucuronidase. Within the multiple banding pattern of the lysosomal enzyme, a faintly staining group of bands in the more acidic range (mean pI 5.4) became more pronounced while a major group (mean pI 5.9) faded slightly. The correlation between the presence or absence of the microsomal beta-glucuronidase and distinct proportions of the two lysosomal enzyme forms was confirmed in vivo. The less acidic form (pI 5.9) prevailed in the presence (kidney, liver), the more acidic form (pI 5.4) in the absence of the microsomal enzyme (spleen). The two lysosomal forms differed also in their apparent molecular weight by approx. 1500 (Mr 71 500 versus 73 000). In order to elucidate the biosynthetic relationship between the microsomal enzyme and the two lysosomal enzyme forms we interfered with their processing in cultured hepatocytes. The addition of the protease/esterase inhibitor phenyl-methyl-sulfonyl-fluoride caused the disappearance of the microsomal and the appearance of the acidic pI 5.4 lysosomal enzyme within 24 h; with chloroquine, the microsomal enzyme remained nd no lysosomal pI 5.4 enzyme appeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Zonal differences of alpha-glucosidases in human kidney: studies in controls and in patients with glycogenosis type II.

In the kidneys of two infants who died from glycogenosis type II (deficiency of lysosomal acid alpha-glucosidase) the activity of alpha-glucosidase at acid pH was absent only from the medulla but not the cortex. This prompted an investigation of acid and neutral alpha-glucosidases of the two zones of normal human kidney and of liver. In the kidney medulla, a single, fast migrating electrophoretic band was active at neutral but not at acid pH. In the cortex, three additional bands were detected at neutral pH and two in the liver. One slowly migrating band was unique to the cortex and active over a broad pH range. It had comparatively high sensitivity to the inhibitor turanose and high heat stability. Its properties suggested a close relationship or identity to glucoamylase of the intestinal brush border membrane and to alpha-glucosidase in leukocytes and amniotic fluid and cells.

Child↗
PubMed1983

IgE production in rat fascioliasis.

F. hepatica infection of rats caused a prolonged elevation of serum total IgE reflecting the continued presence of live worms in the host. Infection with 40 metacercariae stimulated higher total IgE levels than infection with 20 metacercariae. The parasite specific IgE response was biphasic, the first peak coinciding with the migratory phase in the liver parenchyma and the second with the establishment of flukes in the bile ducts.

Animals↗
PubMed1982

Expression of beta-glucuronidase haplotypes in prototype and congenic mouse strains.

A gene complex consists of a structural gene with its associated regulatory information; together they behave as the functional and evolutionary unit of mammalian chromosomes. The use of congenic lines, in which alternate forms, or haplotypes, of a gene complex are transferred into a common genetic background by repeated backcrossing, provides a means of comparing the regulatory properties of different haplotypes of a gene complex without the complications introduced by extraneous genetic differences. We have now carried out such a study of the A, B, and H haplotypes of the beta-glucuronidase gene complex, [Gus], in mice. These haplotypes were derived from strains A/J, C57BL/6J, and C3H/HeJ and were compared against the C57BL/6J genetic background. Enzyme structure was compared in terms of charge (isoelectric point), stability (rate of thermal denaturation), substrate affinity (for 4 MU glucuronide), and antigenicity (reactivity with a standard antibody). Compared to the B form, the enzyme coded by the A haplotype has a lower isoelectric point, and that coded by the H haplotype is less stable. The decreased stability is the result of a lower activation energy for the thermal denaturation reaction. These differences were maintained in the congenic strains. All three enzyme forms showed identical substrate affinities. Antigenicity per enzyme unit was also identical for all three, indicating that none lacks an antigenic site possessed by the others and that they all possess the same catalytic activity per molecule. The expression of alleles of the Gus-t temporal locus within the gene complex was not affected by transfer into the C57BL/6 genetic background. The same developmental switches in enzyme activity were seen in each case. Transfer into the C57Bl/6 background also did not affect expression of the Gus-r regulator determining androgen inducibility of beta-glucuronidase synthesis in kidney epithelial cells. However, enzyme accumulation in induced cells was altered when the haplotypes were transferred into the C57BL/6 genetic background. Since the rate of synthesis was not affected, it suggests that the genetic differences between strains that are not linked to the [Gus] complex affect the rate of enzyme loss by degradation or secretion. Beta-Glucuronidase in liver is present in both lysosomes and endoplasmic reticulum (microsomes). The relative amount of enzyme at each site depended on both the indentity of the structural allele and the function of unlinked genetic modifiers. Within the C57BL/6 background the percentage of total enzyme present in the microsome fraction was the order A greater than B greater than H. For the H form of the enzyme the percentage was appreciably greater in the C3H genetic background compared to C57BL/6. As expected, then, the [Gus] complex contains all of the genetic determinants of enzyme structure detected by thermal stability and isoelectric point measurements...

Animals↗
PubMed1982

A new high performance liquid chromatography (HPLC) method for the quantitation of strychnine in urine and tissue extracts.

A high performance liquid chromatography (HPLC) method was developed for the quantitation of strychnine in urine of children with nonketotic hyperglycinaemia and other developmental disorders treated with the alkaloid. Mobile and stationary phases were polar, i.e. methanol-water-330 g/kg ammonia (volumes, 85 ml + 14.2 ml + 0.8 ml) and LiChrosorb Si-60, 7 microns. Brucine was the internal standard. Extraction was performed by the Extrelut technique. At strychnine nitrate concentrations in urine of 21, 126, and 70 micrograms/l, recovery was 92.1 +/- 8.7, 98.1 +/- 2.7, and 102.5 +/- 2.7%. A child with nonketotic hyperglycinaemia under continued strychnine treatment excreted 1 to 13.6% of the daily dose unmetabolized in urine. The method was also suitable for the estimation of unreacted strychnine in tissue extracts. The fast disappearance in vitro of strychnine from a guinea pig liver preparation was confirmed.

Amino Acid Metabolism, Inborn Errors↗
PubMed1981

Evidence for a close spatial location of the binding sites for CO2 and for photosystem II inhibitors.

1. CO2-depletion of thylakoid membranes results in a decrease of binding affinity of the Photosystem II (PS II) inhibitor atrazine. The inhibitory efficiency of atrazine, expressed as I50-concentration (50% inhibition) of 2,6-dichlorophenolindophenol reduction, is the same in CO2-depleted as well as in control thylakoids. This shows that CO2-depletion results in a complete inactivation of a part of the total number of electron transport chains. 2. A major site of action of CO2, which had previously been located between the two electron acceptor quinone molecule B (or R) and Photosystem II inhibitor atrazine as suggested by the following observations: (a) CO2-depletion results in a shift of the binding constant (kappa b) of [14C]atrazine to thylakoid membranes indicating a decreased affinity of atrazine to membrane; (b) trypsin treatment, which is known to modify the Photosystem II complex at the level of B, strongly diminishes CO2 stimulation of electron transport reactions in CO2-depleted membranes; and (c) thylakoids from atrazine-resistant plants, which contain a Photosystem II complex modified at the inhibitor binding site, show an altered CO2-stimulation of electron flow. 3. CO2-depletion does not produce structural changes in enzyme complexes involved in Photosystem II function of thylakoid membranes, as shown by freeze-fracture studies using electron microscopy.

Atrazine↗
PubMed1981

Photoaffinity labeling of an herbicide receptor protein in chloroplast membranes.

2-Azido-4-ethylamino-6-isopropylamino-s-triazine (azido-atrazine) inhibits photosynthetic electron transport at a site identical to that affected by atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine). The latter is a well-characterized inhibitor of photosystem II reactions. Azido-atrazine was used as a photoaffinity label to identify the herbicide receptor protein; UV irradiation of chloroplast thylakoids in the presence of azido[(14)C]atrazine resulted in the covalent attachment of radioactive inhibitor to thylakoid membranes isolated from pea seedlings and from a triazine-susceptible biotype of the weed Amaranthus hybridus. No covalent binding of azido-atrazine was observed for thylakoid membranes isolated from a naturally occurring triazine-resistant biotype of A. hybridus. Analysis of thylakoid polypeptides from both the susceptible and resistant A. hybridus biotypes by sodium dodecyl sulfate/polyacrylamide gel electrophoresis, followed by fluorography to locate (14)C label, demonstrated specific association of the azido[(14)C]atrazine with polypeptides of the 34- to 32-kilodalton size class in susceptible but not in resistant membranes.

Journal Article↗
PubMed1980

Morphological studies in dogs with chronic pancreatic insufficiency.

The pancreas of dogs with the clinical syndrome of chronic pancreatic insufficiency was examined macroscopically, by light- and electron microscopy and immunohistochemically. The pancreatic tissue was reduced in volume, the lobular architecture was disturbed and the ductal system prominent. Many acini were shrunken and contained cells with pyknotic nuclei. The islets of Langerhans were highly irregular, often difficult to identify. Many B cells occurred isolated within the exocrine tissue. Ultrastructurally, changes in the acinar cells included alterations in the chromatin pattern and dilatation of the cisternae of the rough endoplasmic reticulum. In endocrine cells nuclear deformations, chromatin condensation and progressive loss of secretory granules were seen, accompanied by vacuolization of the cytoplasm. The changes included all endocrine cell types. This complex of pancreatic lesions is considered to be of degenerative origin. The aetiology of the disease is unknown.

Animals↗
PubMed1979

Modification of Herbicide Binding to Photosystem II in Two Biotypes of Senecio vulgaris L.

THE PRESENT STUDY COMPARES THE BINDING AND INHIBITORY ACTIVITY OF TWO PHOTOSYSTEM II INHIBITORS: 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron [DCMU]) and 2-chloro-4-(ethylamine)-6-(isopropyl amine)-S-triazene (atrazine). Chloroplasts isolated from naturally occurring triazine-susceptible and triazine-resistant biotypes of common groundsel (Senecio vulgaris L.) showed the following characteristics. (a) Diuron strongly inhibited photosynthetic electron transport from H(2)O to 2,6-dichlorophenolindophenol in both biotypes. Strong inhibition by atrazine was observed only with the susceptible chloroplasts. (b) Hill plots of electron transport inhibition data indicate a noncooperative binding of one inhibitor molecule at the site of action for both diuron and atrazine. (c) Susceptible chloroplasts show a strong diuron and atrazine binding ((14)C-radiolabel assays) with binding constants (K) of 1.4 x 10(-8) molar and 4 x 10(-8) molar, respectively. In the resistant chloroplasts the diuron binding was slightly decreased (K = 5 x 10(-8) molar), whereas no specific atrazine binding was detected. (d) In susceptible chloroplasts, competitive binding between radioactively labeled diuron and non-labeled atrazine was observed. This competition was absent in the resistant chloroplasts.We conclude that triazine resistance of both intact plants and isolated chloroplasts of Senecio vulgaris L. is based upon a minor modification of the protein in the photosystem II complex which is responsible for herbicide binding. This change results in a specific loss of atrazine (triazine)-binding capacity.

Journal Article↗