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Biomedical subjects

H Pichler

Publications and source records attributed to H Pichler.

At least 19 recordsLinked to original sources
PubMed2001

A subfraction of the yeast endoplasmic reticulum associates with the plasma membrane and has a high capacity to synthesize lipids.

Large parts of the endoplasmic reticulum of the yeast, Saccharomyces cerevisiae, are located close to intracellular organelles, i.e. mitochondria and the plasma membrane, as shown by fluorescence and electron microscopy. Here we report the isolation and characterization of the subfraction of the endoplasmic reticulum that is closely associated with the plasma membrane. This plasma membrane associated membrane (PAM) is characterized by its high capacity to synthesize phosphatidylserine and phosphatidylinositol. As such, PAM is reminiscent of MAM, a mitochondria associated membrane fraction of the yeast [Gaigg, B., Simbeni, R., Hrastnik, C., Paltauf, F. & Daum, G. (1995) Biochim. Biophys. Acta 1234, 214-220], although the specific activity of phosphatidylserine synthase and phosphatidylinositol synthase in PAM exceeds several-fold the activity in MAM and also in the bulk endoplasmic reticulum. In addition, several enzymes involved in ergosterol biosynthesis, namely squalene synthase (Erg9p), squalene epoxidase (Erg1p) and steroldelta24-methyltransferase (Erg6p), are highly enriched in PAM. A possible role of PAM in the supply of lipids to the plasma membrane is discussed.

Blotting, Western↗
PubMed2000

An enzyme linked immunoassay for the determination of deoxynivalenol in wheat based on chicken egg yolk antibodies.

An indirect competitive enzyme linked immunoassay (ELISA) for the detection of the Fusarium mycotoxin deoxynivalenol (DON) in wheat was developed. Instead of the much more common antibody isolation from mammal serum, DON specific antibodies were, for the first time, isolated from the eggs of previously immunized hens. The limit of detection was 2 microg/L for standard curves and spiked wheat extracts. Recoveries for naturally contaminated samples (200-525 microg/kg) were between 80 and 125% compared with GC-ECD data. Concentrations for naturally contaminated samples were chosen with regard to current Austrian guidelines concerning DON levels in produce intended for human consumption, recommending a maximum of 500 microg DON/kg.

Animals↗
PubMed1999

PDR16 and PDR17, two homologous genes of Saccharomyces cerevisiae, affect lipid biosynthesis and resistance to multiple drugs.

The Saccharomyces cerevisiae open reading frame YNL231C was recently found to be controlled by the multiple drug resistance regulator Pdr1p. Here we characterize YNL231C (PDR16) and its homologue YNL264C (PDR17). Deletion of PDR16 resulted in hypersensitivity of yeast to azole inhibitors of ergosterol biosynthesis. While no increase in drug sensitivity was found upon deletion of PDR17 alone, a Deltapdr16,Deltapdr17 double mutant was hypersensitive to a broad range of drugs. Both mutations caused significant changes of the lipid composition of plasma membrane and total cell extracts. Deletion of PDR16 had pronounced effects on the sterol composition, whereas PDR17 deletion mainly affected the phospholipid composition. Thus, Pdr16p and Pdr17p may regulate yeast lipid synthesis like their distant homologue, Sec14p. The azole sensitivity of the PDR16-deleted strain may be the result of imbalanced ergosterol synthesis. Impaired plasma membrane barrier function resulting from a change in the lipid composition appears to cause the increased drug sensitivity of the double mutant strain Deltapdr16,Deltapdr17. The uptake rate of rhodamine-6-G into de-energized cells was shown to be almost 2-fold increased in a Deltapdr16,Deltapdr17 strain as compared with wild-type and Deltapdr5 strains. Collectively, our results indicate that PDR16 and PDR17 control levels of various lipids in various compartments of the cell and thereby provide a mechanism for multidrug resistance unrecognized so far.

Base Sequence↗
PubMed1999

Specific sterols required for the internalization step of endocytosis in yeast.

Sterols are major components of the plasma membrane, but their functions in this membrane are not well understood. We isolated a mutant defective in the internalization step of endocytosis in a gene (ERG2) encoding a C-8 sterol isomerase that acts in the late part of the ergosterol biosynthetic pathway. In the absence of Erg2p, yeast cells accumulate sterols structurally different from ergosterol, which is the major sterol in wild-type yeast. To investigate the structural requirements of ergosterol for endocytosis in more detail, several erg mutants (erg2Delta, erg6Delta, and erg2Deltaerg6Delta) were made. Analysis of fluid phase and receptor-mediated endocytosis indicates that changes in the sterol composition lead to a defect in the internalization step. Vesicle formation and fusion along the secretory pathway were not strongly affected in the ergDelta mutants. The severity of the endocytic defect correlates with changes in sterol structure and with the abundance of specific sterols in the ergDelta mutants. Desaturation of the B ring of the sterol molecules is important for the internalization step. A single desaturation at C-8,9 was not sufficient to support internalization at 37 degrees C whereas two double bonds, either at C-5,6 and C-7,8 or at C-5,6 and C-8,9, allowed internalization.

Carboxypeptidases↗
PubMed1997

Exchange blood transfusion in severe falciparum malaria: retrospective evaluation of 61 patients treated with, compared to 63 patients treated without, exchange transfusion.

The rationale for exchange blood transfusion (ET) in severe falciparum malaria is threefold: reduction of parasitaemia, reduction of presumptive 'toxic' factors, and improvement of the rheological quality of the blood. We evaluated the records of 61 patients treated with ET to describe the present status of malaria treatment in Germany, Austria and Switzerland and to assess the efficacy of ET. Clinical data of 61 patients treated with ET were compared to data of 63 patients treated in 2 hospitals where ETs were generally not performed. We found that exchange transfusion is applied according to the clinician's subjective impression rather than strict guidelines. Logistic regression analysis adjusting for the differences in clinical parameters between patients treated with or without ET did not identify treatment as a prognostic indicator (odds ratio for relative risk of death with ET: 1.3; 95% CI: 0.4-4.9). Exchange transfusion did not significantly improve the unfavourable prognosis in cases of severe falciparum malaria. However, failure to reach statistical significance may be due to the retrospective design of the study and therefore non-systematic approach.

Adult↗
PubMed1992

[Differential diagnosis of fever after returning from the tropics].

Fever is the cardinal symptom of many infections in travellers returning from the tropics and is second in place only to infectious diarrhea. Once the obvious causes of fever in an individual patient have been eliminated, it may be very difficult to find the cause of fever. Fevers can be distinguished by their length of duration and divided into acute fevers i.e. up to 3 weeks duration and chronic fevers i.e. more than 3 weeks duration. Whether fever goes along with leucopenia or a normal white blood cell count on the one hand or with leucocytosis on the other hand is of differential diagnostic value. A schedule based on these two parameters will be presented to simplify differential diagnostic considerations. Two rules of thumb will be stressed: (1) Each febrile illness, even febrile diarrhea, jaundice or meningitis, is to be considered a malaria until it is excluded. (2) Patients returning from tropical areas might suffer from banal infections such as pneumonia, urinary tract infections, cholangitis, etc. as well.

Diagnosis, Differential↗
PubMed1992

[HDL cholesterol as a sensitive diagnostic parameter in malaria].

In patients with malaria the lipid parameters triglycerides, cholesterol, and HDL-cholesterol were determined routinely. At the time of admission hypertriglyceridemia, hypocholesterolemia, and an extreme decrease in HDL-cholesterol were found. This dyslipoproteinemia was present in cases of falciparum malaria, as well as in cases of benign tertian malaria. The extent of HDL-cholesterol decrease showed no correlation to the severity of the clinical course of disease. HDL-cholesterol has proven to be an independent diagnostic laboratory finding in cases of suspected malarial infection. This parameter displays high diagnostic sensitivity, but no specificity for malaria.

Adult↗
PubMed1987

Influence of television on photosensitive epileptics.

We examined 32 epileptics (20 female; 12 male; aged 6-73 years) who had displayed photoconvulsive reactions to flickering light in the EEG; they were examined with regard to their risks of getting epileptic seizures upon watching television (TV) under certain conditions. On a colour TV set each patient was shown a 3-min videofilm with slow- and fast-moving parts under 16 different conditions. The conditions had the following variables: (1) colour - monochrome; (2) dark room - light room, and (3) four different distances from the screen. In addition, each patient was subjected for 3 min to manipulated image interferences, including the vertical rolling of the picture. The results of this TV stimulation were always negative, i.e. in no patient did TV provoke a reproducible paroxysmal discharge in the EEG, nor was there any epileptic seizure. Our findings are discussed in connection with the corresponding literature.

Adolescent↗