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Biomedical subjects

L Sass

Publications and source records attributed to L Sass.

13 recordsLinked to original sources
PubMed2003

Anhedonia, self-experience in schizophrenia, and implications for treatment.

Anhedonia - the inability to experience pleasure - is a symptom of several psychiatric disorders such as depression, drug and alcohol dependence, but also schizophrenia. The concept of anhedonia played a major role in psychiatric and psychoanalytic explanations of psychotic behavior. The relationship between notions of anhedonia and of mental evolution and regression (in the work of Myerson and Bleuler) is discussed. The non-evolutionist views of Rado and Meehl are described. Then the concept of anhedonia is discussed in relationship to the phenomenological approach of Sass and Parnas, who view anhedonia as one manifestation of a self-disturbance or self-disorder that is fundamental in schizophrenia. Concerning treatment of anhedonia, it was often hypothesized that anhedonia is associated with a dysfunction of the mesolimbic dopaminergic reward system. However, studies in humans and non-human animal models indicate that dysfunction of central dopaminergic neurotransmission interferes with the process of motivation rather than with the ability to experience pleasure; the latter may be more mediated by the opioidergic and serotonergic neurotransmission. Understanding the neurobiological correlates of motivation and pleasure may provide new options to treat anhedonia in patients with schizophrenia.

Animals↗
PubMed2000

Nuclear localization of a hypoxia-inducible novel non-symbiotic hemoglobin in cultured alfalfa cells.

We have isolated a 483-bp-long full-length cDNA clone encoding a non-symbiotic hemoglobin called Mhb1, the first one found in alfalfa. This non-symbiotic hemoglobin is a single copy gene localized in linkage group 4 in diploid Medicago genome. The Mhb1 mRNA was found only in the roots of alfalfa plants. The Mhb1 gene was inducible by hypoxia and showed no induction by cold stress treatment. The Mhb1 transcript level increased at the G2/M boundary in a synchronized alfalfa cell suspension culture. The majority of Mhb1 protein was shown to be localized in the nucleus and smaller amounts were detected in the cytoplasm. A potential link to the nitric oxide signalling pathway is also discussed.

Amino Acid Sequence↗
PubMed2000

A novel aldose/aldehyde reductase protects transgenic plants against lipid peroxidation under chemical and drought stresses.

Rapid accumulation of toxic products from reactions of reactive oxygen species (ROS) with lipids and proteins significantly contributes to the damage of crop plants under biotic and abiotic stresses. Here we have identified a stress-activated alfalfa gene encoding a novel plant NADPH-dependent aldose/aldehyde reductase that also exhibited characteristics of the homologous human enzyme. The recombinant alfalfa enzyme is active on 4-hydroxynon-2-enal, a known cytotoxic lipid peroxide degradation product. Ectopic synthesis of this enzyme in transgenic tobacco plants provided considerable tolerance against oxidative damage caused by paraquat and heavy metal treatment. These transformants could also resist a long period of water deficiency and exhibited improved recovery after rehydration. We found a reduced production of lipid peroxidation-derived reactive aldehydes in these transformed plants under different stresses. These studies reveal a new and efficient detoxification pathway in plants.

Adaptation, Physiological↗
PubMed1999

Plants ectopically expressing the iron-binding protein, ferritin, are tolerant to oxidative damage and pathogens.

Transgenic tobacco plants that synthesize alfalfa ferritin in vegetative tissues--either in its processed form in chloroplasts or in the cytoplasmic nonprocessed form--retained photosynthetic function upon free radical toxicity generated by iron excess or paraquat treatment. Progeny of transgenic plants accumulating ferritin in their leaves exhibited tolerance to necrotic damage caused by viral (tobacco necrosis virus) and fungal (Alternaria alternata, Botrytis cinerea) infections. These transformants exhibited normal photosynthetic function and chlorophyll content under greenhouse conditions. We propose that by sequestering intracellular iron involved in generation of the very reactive hydroxyl radicals through a Fenton reaction, ferritin protects plant cells from oxidative damage induced by a wide range of stresses.

Alternaria↗
PubMed1998

UV-B-induced differential transcription of psbA genes encoding the D1 protein of photosystem II in the Cyanobacterium synechocystis 6803.

UV-B irradiation of intact Synechocystis sp. PCC 6803 cells results in the loss of photosystem II activity, which can be repaired via de novo synthesis of the D1 (and D2) reaction center subunits. In this study, we investigated the effect of UV-B irradiation on the transcription of the psbA2 and psbA3 genes encoding identical D1 proteins. We show that UV-B irradiation increases the level of psbA2 mRNA 2-3-fold and, more dramatically, it induces a 20-30-fold increase in the accumulation of the psbA3 mRNA even at levels of irradiation too low to produce losses of either photosystem II activity or D1 protein. The induction of psbA3 transcript accumulation is specific for UV-B light (290-330 nm). Low intensity UV-A emission (330-390 nm) and white light induce only a small, at most, 2-3-fold enhancement, whereas no effect of blue light was observed. Expression patterns of chimeric genes containing the promoter regions of the psbA2, psbA3 genes fused to the firefly luciferase (luc) reporter gene indicate that (i) transcription of psbA2/luc and psbA3/luc transgenes was elevated, similarly to that of the endogenous psbA genes, by UV-B irradiation, and that (ii) a short, 80-base pair psbA3 promoter fragment is sufficient to maintain UV-B-induced transcription of the luc reporter gene. Furthermore, our findings indicate that UV-B-induced expression of the psbA2 and psbA3 genes is a defense response against UV-B stress, which is regulated, at least, partially at the level of transcription and does not require active electron transport.

Base Sequence↗
PubMed1996

UV-B-induced inhibition of photosystem II electron transport studied by EPR and chlorophyll fluorescence. Impairment of donor and acceptor side components.

Inhibition of photosystem II electron transport by UV-B radiation has been studied in isolated spinach photosystem II membrane particles using low-temperature EPR spectroscopy and chlorophyll fluorescence measurements. UV-B irradiation results in the rapid inhibition of oxygen evolution and the decline of variable chlorophyll fluorescence. These effects are accompanied by the loss of the multiline EPR signal arising from the S2 state of the water-oxidizing complex and the induction of Signal IIfast originating from stabilized Try-Z+. The EPR signals from the QA-Fe2+ acceptor complex, Tyr-D+, and the oxidized non-heme iron (Fe3+) are also decreased during the course of UV-B irradiation, but at a significantly slower rate than oxygen evolution and the multiline signal. The decrease of the Fe3+ signal at high g values (g = 8.06, g = 5.6) is accompanied by the induction of another EPR signal at g = 4.26 that arises most likely from the same Fe3+ ion in a modified ligand environment. UV-B irradiation also affects cytochrome b-559. The g = 2.94 EPR signal that arises from the dark- oxidized form is enhanced, whereas the light inducible g = 3.04 signal that arises from the photo-oxidizable population of cytochrome b-559 is diminished. UV-B irradiation also induces the degradation of the D1 reaction center protein. The rate of the D1 protein loss is slower than the inhibition of oxygen evolution and of the multiline signal but follows closely the loss of Signal IIslow, the QA-Fe2+ and the Fe3+ EPR signals, as well as the release of protein-bound manganese. It is concluded from the results that UV-B radiation affects photosystem II redox components at both the donor and acceptor side. The primary damage occurs at the water-oxidizing complex. Modification and/or inactivation of tyrosine-D, cytochrome b-559, and the QAFe2+ acceptor complex are subsequent events that coincide more closely with the UV-B-induced damage to the protein structure of the photosystem II reaction center.

Chlorophyll↗
PubMed1993

[Surgical indication for hip endoprosthesis].

The authors give a short review of the history, development, results of the joint endoprosthetic, regarding mainly to the hip replacement, based on their own data and on international references. It is suggested that the development of the modern surgical technique changed the condition of the indication which needs a wide publicity.

Cementation↗
PubMed1990

[The significance of the environment for delivery at a special department].

A material of 292 normal pregnant women was subdivided at random for delivery either in the traditional delivery room or a newly established environmental room. The alterations in the physical environment of delivery did not result in more numerous spontaneous deliveries. A high frequency of episiotomies, stimulation of contractions and artificial deliveries in primiparae occurred particularly when it is considered that two thoroughly investigated groups of low-risk pregnant women were concerned. However, qualitative differences in the experience of the course of delivery were found in favour of the environmental room. The quality of the experience of delivery did not depend so much on the physical environment but more on contact with the staff members responsible for conduct of the delivery.

Delivery, Obstetric↗
PubMed1989

[Experience with the cementless hip prosthesis, with special reference to the implantation of prosthesis stems].

Authors report on their experiences gained during 7 years with 102 PM (Aesculap) and 76 Etropal cementless hip endoprosthesis and with the implantation without sticking of 264 standard prosthesis stems. They explain their results with bone rebuilding that can be certified also by Roentgenograms. The lack of success in a few per cent of the cases can be explained mainly by technical insufficience.

Cementation↗
PubMedDate not supplied

Biomechanical aspects of femoral stem anchoring during total hip replacement.

Stem instability is the major cause of complications following total hip replacement. To prevent its onset, the authors based their method on Wolff's law of bone transformation. Of the known prostheses, the straight-stem one fitting best to the shape of medullar cavity was chosen and by its sagittal enlargement in three different sizes a new stem collection was designed. Stems providing the closest fit to the medullar cavity were selected by computer-assisted adjustment to three-directional X-ray pictures. The principle seems to be supported by preliminary results.

Biomechanical Phenomena↗