Catchment properties and the photosynthetic trait composition of freshwater plant communities

Unlike in land plants, photosynthesis in many aquatic plants relies on bicarbonate in addition to carbon dioxide (CO2) to compensate for the low diffusivity and potential depletion of CO2 in water. Concentrations of bicarbonate and CO2 vary greatly with catchment geology. In this study, we investigate whether there is a link between these concentrations and the frequency of freshwater plants possessing the bicarbonate use trait. We show, globally, that the frequency of plant species with this trait increases with bicarbonate concentration. Regionally, however, the frequency of bicarbonate use is reduced at sites where the CO2 concentration is substantially above the air equilibrium, consistent with this trait being an adaptation to carbon limitation. Future anthropogenic changes of bicarbonate and CO2 concentrations may alter the species compositions of freshwater plant communities.

Fever in pregnancy and the risk of congenital malformations: a cohort study

Background

In a variety of animal species, hyperthermia in pregnancy has been recognized as teratogenic. Hyperthermia interferes with protein synthesis via heat-shock proteins, which can entail membrane disruption, cell death, vascular disruption, and placental infarction. This can induce severe fetal malformations or death. Fever during pregnancy, especially during embryogenesis, has also been associated with congenital malformations in human offspring.

The purpose of this large cohort study of clinically recognized pregnancies was to investigate whether fever during first trimester was associated with an increased risk of congenital malformations in the offspring.

Methods

The Danish National Birth Cohort is a population-based cohort of 100,418 pregnant women and their offspring recruited in 1996 to 2002. Information on fever during pregnancy was collected prospectively by means of two telephone interviews.

The study population comprised the 77,344 pregnancies enrolled in the Danish National Birth Cohort where self-reported information on fever during first trimester of pregnancy was available. Pregnancy outcomes were identified through linkage with the National Patient Registry. Congenital malformations within the first three and a half years of life were categorized according to EUROCAT’s classification criteria. Logistic regression models were used to estimate the associations between fever in first trimester and overall congenital malformations and congenital malformations by subgroups.

Results

Eight thousand three hundred twenty-one women reported fever during first trimester (10.8%) and 2876 infants were diagnosed with a congenital malformation (3.7%). Fever during first trimester did not affect the risk of overall fetal congenital malformation (OR 0.99, 95% CI 0.88–1.12). The subgroup analyses indicated slightly higher risk of congenital anomalies in the eye, ear, face and neck (OR 1.29, 95% CI 0.78–2.12) and in the genitals (OR 1.17, 95% CI 0.79–1.12), whereas lower risk of malformations in the nervous system (OR 0.47, 95% CI 0.21–1.08), the respiratory system (OR 0.56, 95% CI 0.23–1.29) and in the urinary subgroup (OR 0.58, 95% CI 0.35–0.99) was suggested, the latter constituting the only statistically significant finding.

Conclusions

Overall, this study did not show any association between maternal fever in pregnancy and risk of congenital anomalies.

What is bizarre in bizarre delusions? A critical review

Diagnostic and Statistical Manual of Mental Disorder, Fourth Edition (DSM-IV) treats the presence of bizarre delusions (BD) as the heaviest-weighted clinical criterion of schizophrenia. Although BD play a major role in contemporary diagnostic systems, only a few empirical studies explore this issue. These studies provide highly heterogenous results because they are based on different experimental paradigms, in terms of definition, clinical sample, and number of raters. Here, we first discuss the psychopathological sources of the concept of BD, which were initially described as either nonsensical or incomprehensible. Then, we provide a critical review of contemporary studies on the reliability of BD and their methodological and conceptual limitations. Current approaches have focused intensely on BD's reliability and have defined BD strictly in terms of delusional content--mainly in terms of the physical impossibility or the cultural or historical incomprehensibility of the delusional claims. These approaches have neglected formal features of experience that underlie BD and the crucial issue of the nature and validity of BD. In the discussion, we argue that clinical diagnosis of BD cannot be limited to delusional contents alone and requires taking into account the subjective side of BD (how altered experience manifests itself) as well as the conditions of intersubjective encounter (how BD are expressed to and experienced by the clinician). The notion of "bizarreness" in schizophrenia is not purely theoretical; it has practical relevance for the therapeutic encounter and implications on further empirical research and on diagnostic approaches.

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.

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.

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.

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.

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.

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.

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.

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.

Thermoluminescence studies on the function of Photosystem II in the desiccation tolerant lichen Cladonia convoluta

The effect of desiccation and rehydration on the function of Photosystem II has been studied in the desiccation tolerant lichen Cladonia convoluta by thermoluminescence. We have shown that in functional fully hydrated thalli thermoluminescence signals can be observed from the recombination of the S2(3)QB (-) (B band), S2QA (-) (Q band), Tyr-D(+)QA (-) (C band) and Tyr-Z(+)(His(+))QA (-) (A band) charge stabilization states. These thermoluminescence signals are completely absent in desiccated thalli, but rapidly reappear on rehydration. Flash-induced oscillation in the amplitude of the thermoluminescence band from the S2(3)QB (-) recombination shows the usual pattern with maxima after 2 and 6 flashes when rehydration takes place in light. However, after rehydration in complete darkness, there is no thermoluminescence emission after the 1 st flash, and the maxima of the subsequent oscillation are shifted to the 3rd and 7th flashes. It is concluded that desiccation of Cladonia convoluta converts PS II into a nonfunctional state. This state is characterized by the lack of stable charge separation and recombination, as well as by a one-electron reduction of the water-oxidizing complex. Restoration of PS II function during rehydration can proceed both in the light and in darkness. After rehydration in the dark, the first charge separation act is utilized in restoring the usual oxidation state of the water-oxidizing comples.

[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.

Inactivation of photosynthetic oxygen evolution by UV-B irradiation: A thermoluminescence study

The influence of UV-B irradiation on photosynthetic oxygen evolution by isolated spinach thylakoids has been investigated using thermoluminescence measurements. The thermoluminescence bands arising from the S2QB (-) (B band) and S2QA (-) (Q band) charge recombination disappeared with increasing UV-B irradiation time. In contrast, the C band at 50°C, arising from the recombination of QA (-) with an accessory donor of Photosystem II, was transiently enhanced by the UV-B irradiation. The efficiency of DCMU to block QA to QB electron transfer decreased after irradiation as detected by the incomplete suppression of the B band by DCMU. The flash-induced oscillatory pattern of the B band was modified in the UV-B irradiated samples, indicating a decrease in the number of centers with reduced QB. Based on the results of this study, UV-B irradiation is suggested to damage both the donor and acceptor sides of Photosystem II. The damage of the water-oxidizing complex does not affect a specific S-state transition. Instead, charge stabilization is enhanced on an accessory donor. The acceptor-side modifications decrease the affinity of DCMU binding. This effect is assumed to reflect a structural change in the QB/DCMU binding site. The preferential loss of dark stable QB (-) may be related to the same structural change or could be caused by the specific destruction of reduced quinones by the UV-B light.

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.

[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.