The redox state of the mantle during and just after core formation

Siderophile elements are depleted in the Earth's mantle, relative to chondritic meteorites, as a result of equilibration with core-forming Fe-rich metal. Measurements of metal-silicate partition coefficients show that mantle depletions of slightly siderophile elements (e.g. Cr, V) must have occurred at more reducing conditions than those inferred from the current mantle FeO content. This implies that the oxidation state (i.e. FeO content) of the mantle increased with time as accretion proceeded. The oxygen fugacity of the present-day upper mantle is several orders of magnitude higher than the level imposed by equilibrium with core-forming Fe metal. This results from an increase in the Fe2O3 content of the mantle that probably occurred in the first 1Ga of the Earth's history. Here we explore fractionation mechanisms that could have caused mantle FeO and Fe2O3 contents to increase while the oxidation state of accreting material remained constant (homogeneous accretion). Using measured metal-silicate partition coefficients for O and Si, we have modelled core-mantle equilibration in a magma ocean that became progressively deeper as accretion proceeded. The model indicates that the mantle would have become gradually oxidized as a result of Si entering the core. However, the increase in mantle FeO content and oxygen fugacity is limited by the fact that O also partitions into the core at high temperatures, which lowers the FeO content of the mantle. (Mg,Fe)(Al,Si)O3 perovskite, the dominant lower mantle mineral, has a strong affinity for Fe2O3 even in the presence of metallic Fe. As the upper mantle would have been poor in Fe2O3 during core formation, FeO would have disproportionated to produce Fe2O3 (in perovskite) and Fe metal. Loss of some disproportionated Fe metal to the core would have enriched the remaining mantle in Fe2O3 and, if the entire mantle was then homogenized, the oxygen fugacity of the upper mantle would have been raised to its present-day level.

Olea europaea leaf extract exerts L-type Ca(2+) channel antagonistic effects

ETHNOPHARMACOLOGICAL RELEVANCE

In Southern Europe Olea europaea leafs are known as a folk remedy for hypertension. Cardiovascular diseases are still the leading causes of morbidity and mortality in industrialized countries with hypertension being one of the main risk factors.

AIM OF THE STUDY

We investigated effects of a commercial Olea europaea leaf extract (OLE) on isolated hearts and cultured cardiomyocytes.

MATERIALS AND METHODS

Isolated rabbit hearts were perfused according to the Langendorff technique and connected to a 256-channel epicardial mapping system. Voltage clamp experiments were performed in cultured neonatal rat cardiomyocytes using a perforated-patch technique.

RESULTS

OLE caused a concentration-depended decrease in systolic left ventricular pressure and heart rate as well as an increase in relative coronary flow and a slight, but not significant prolongation of PQ-time. There were no significant changes between the groups in the activation-recovery interval and its dispersion, total activation time, peak-to-peak amplitude, percentage of identical breakthrough-points and similar vectors of local activation. Voltage clamp experiments in cultured neonatal rat cardiomyocytes showed a significant decrease in maximum I(Ca,L) by OLE which was reversible upon wash-out.

CONCLUSIONS

OLE suppresses the L-type calcium channel directly and reversibly. Our findings might help to understand the traditional use of OLE in the treatment of cardiovascular disease.

Measurement of induced acrosome reactions in human sperm using physiologic stimuli - relevance for the prediction of fertilization outcome

Fertilization failure following standard in vitro fertilization in couples with normozoospermic men is an as yet unexplained phenomenon. A wide range of gametic disorders as well as environmental factors might contribute to this pathologic condition. One crucial condition appears to be the inability of the spermatozoa to undergo the acrosome reaction (AR). A discriminative test to distinguish fertile from non-fertile spermatozoa would be of utmost interest. In a prospective study, semen samples from men with normal semen parameters and fertilization failure were compared with semen samples from men with normal semen parameters and normal fertilization as to their capacity to undergo the AR. AR was induced using calcium ionophore as well as the physiologic stimuli progesterone and prostaglandin E(1). Discriminance analyses were undertaken to help identify patients with probable fertilization failure. Our data show that in patients with fertilization failure, the capacity of spermatozoa to undergo induced AR is greatly reduced using both unphysiologic and physiologic stimuli. However, physiologic stimuli are more suitable to identify patients with fertilization failure. Using physiologic stimuli, a formula was established to identify patients likely to fail at fertilization.

Loss of glycosylation associated with the T183A mutation in human prion disease

A heterozygous T183A mutation in the prion protein (PrP) gene, PRNP, was identified in a patient with histopathologically confirmed spongiform encephalopathy. Clinically, this form of prion disease was characterized by early-onset dementia as the predominant sign, along with global cerebral atrophy and hypometabolism. The age at onset was 40 years and the disease duration was 4 years. Additional neurological signs including cerebellar ataxia and EEG abnormalities were absent until late stages of the disease. The T183A mutation was not found in non-affected family members. This mutation results in the removal of one of the two consensus sites for glycosylation of PrP. Neuropathological examination revealed severe spongiform degeneration and neuronal loss in the neocortex, putamen and claustrum, small plaque-like PrP-immunoreactive deposits in the molecular layer of the cerebellum, and faint intracellular cytoplasmic PrP immunoreactivity. Western blot analysis of the patient's brain tissue showed protease K-resistant PrP with a definite preponderance of the monoglycosylated form. The additional appearance of a band representing diglycosylated PrPSc strongly suggests that non-mutated PrP also acquires protease resistance in the present setting. Cell culture experiments confirmed previous reports on intracellular retention of the mutant protein in vitro. This is the second report of a disease-causing T183A mutation of PrP, and the clinical, histological and genetic observations strongly suggest that T183A is a disease-causing mutation.

Influence of vitamin E and C supplementation on lipoprotein oxidation in patients with Alzheimer's disease

Because increased oxidation is an important feature of Alzheimer's disease (AD) and low concentrations of antioxidant vitamins C and E have been observed in cerebrospinal fluid (CSF) of AD patients, supplementation with these antioxidants might delay the development of AD. Major targets for oxidation in brain are lipids and lipoproteins. We studied whether supplementation with antioxidative vitamins E and C can increase their concentrations not only in plasma but also in CSF, and as a consequence decrease the susceptibility of lipoproteins to in vitro oxidation. Two groups, each consisting of 10 patients with AD, were for 1 month supplemented daily with either a combination of 400 IU vitamin E and 1000 mg vitamin C, or 400 IU vitamin E alone. We found that supplementation with vitamin E and C significantly increased the concentrations of both vitamins in plasma and CSF. Importantly, the abnormally low concentrations of vitamin C were returned to normal level following treatment. As a consequence, susceptibility of CSF and plasma lipoproteins to in vitro oxidation was significantly decreased. In contrast, the supplementation with vitamin E alone significantly increased its CSF and plasma concentrations, but was unable to decrease the lipoprotein oxidizability. These findings document a superiority of a combined vitamin E + C supplementation over a vitamin E supplementation alone in AD and provide a biochemical basis for its use.

Genetic association of a cystatin C gene polymorphism with late-onset Alzheimer disease

OBJECTIVE

To determine whether the cystatin C gene (CST3) is genetically associated with late-onset Alzheimer disease (AD).

DESIGN

A case-control study with 2 independent study populations of patients with AD and age-matched, cognitively normal control subjects.

SETTING

The Alzheimer's Disease Research Unit at the University Hospital Hamburg-Eppendorf, Hamburg, Germany, for the initial study (n = 260). For the independent multicenter study (n = 647), an international consortium that included the Massachusetts Alzheimer's Disease Research Center at the Massachusetts General Hospital, Boston; the Scientific Institute for Research and Patient Care, Brescia, Italy; and Alzheimer's research units at the Universities of Basel and Zurich, Switzerland, and Bonn, Goettingen, and Hamburg, Germany.

PARTICIPANTS

Five hundred seventeen patients with AD and 390 control subjects.

MEASURES

Molecular testing of the KspI polymorphisms in the 5' flanking region and exon 1 of CST3 and the apolipoprotein E (APOE) genotype. Mini-Mental State Examination scores for both patients with AD and control subjects.

RESULTS

Homozygosity for haplotype B of CST3 was significantly associated with late-onset AD in both study populations, with an odds ratio of 3.8 (95% confidence interval, 1.56-9.25) in the combined data set; heterozygosity was not associated with an increased risk. The odds ratios for CST3 B/B increased from 2.6 in those younger than 75 years to 8.8 for those aged 75 years and older. The association of CST3 B/B with AD was independent of APOE epsilon4; both genotypes independently reduced disease-free survival.

CONCLUSIONS

CST3 is a susceptibility gene for late-onset AD, especially in patients aged 75 years and older. To our knowledge, CST3 B is the first autosomal recessive risk allele in late-onset AD.

Increased lipoprotein oxidation in Alzheimer's disease

Oxidation has been proposed to be an important factor in the pathogenesis of Alzheimer's disease (AD) and amyloid beta is considered to induce oxidation. In biological fluids, including cerebrospinal fluid (CSF), amyloid beta is found complexed to lipoproteins. On the basis of these observations, we investigated the potential role of lipoprotein oxidation in the pathology of AD. Lipoprotein oxidizability was measured in vitro in CSF and plasma from 29 AD patients and found to be significantly increased in comparison to 29 nondemented controls. The levels of the hydrophilic antioxidant ascorbate were significantly lower in CSF and plasma from AD patients. In plasma, alpha-carotene was significantly lower in AD patients compared to controls while alpha-tocopherol levels were indistinguishable between patients and controls. In CSF, a nonsignificant trend to lower alpha-tocopherol levels among AD patients was found. Polyunsaturated fatty acids, the lipid substrate for oxidation, were significantly lower in the CSF of AD patients. Our findings suggest that (i) lipoprotein oxidation may be important in the development of AD and (ii) the in vitro measurement of lipid peroxidation in CSF might become a useful additional marker for diagnosis of AD.

High prevalence of pathogenic mutations in patients with early-onset dementia detected by sequence analyses of four different genes

Clinical differential diagnosis of early-onset dementia (EOD) includes familial Alzheimer disease (FAD) and hereditary prion disease. In both disease entities, postmortem brain histopathological examination is essential for unambiguous diagnosis. Mutations in the genes encoding the presenilins (PS1 and PS2) and amyloid precursor protein (APP) are associated with FAD, whereas mutations in the prion protein (PrP) gene are associated with prion disease. To investigate the proportion of EOD attributable to known genes, we prospectively (i.e., antemortem) screened these four genes for mutations by sequencing genomic PCR products from patients with EOD before age 60 years. Family history for dementia was positive (PFH) in 16 patients, negative (NFH) in 17 patients, and unknown (UFH) in 3 patients. In 12 patients, we found five novel mutations (in PS1, F105L; in PS2, T122P and M239I; and in PrP, Q160X and T188K) and five previously reported mutations (in APP, in three patients who were most likely unrelated, V717I; in PS1, A79V and M139V; and in PrP, P102L and T183A) that are all considered to be disease causing. Of these 12 patients, 9 had PFH. This indicates a detection rate of 56% (9/16) in patients with PFH. We found two mutations (APP V717I) in two of the three UFH patients, and only one mutation (PrP T188K) in 1 of the 17 patients with NFH. We conclude that because of the lack of specific antemortem diagnostic markers for FAD and hereditary prion disease, all four genes should be included in a molecular diagnostic program in patients with EOD who had PFH.

High frequency of mutations in four different disease genes in early-onset dementia

Heterozygous mutations in the genes for amyloid precursor protein (APP), the presenilins (PS1, PS2), prion protein (PrP), neuroserpin, and tau are associated with early-onset dementia (EOD) with or without neurological signs in the early disease stage. To investigate the proportion of EOD without early neurological signs attributable to known genes we prospectively (i.e., ante mortem) screened these six genes for mutations in 36 patients with EOD before age 60. Family history for dementia was positive (PFH) in 16, negative (NFH) in 17, and unknown (UFH) in 3 patients. In 12 patients, we found 5 novel mutations (PS1: F105L; PS2: T122P, M239I; PrP: Q160X, T188K) and 5 previously reported mutations (APP: in three most likely unrelated patients V717I; PS1: A79V, M139V; PrP: P102L, T183A) that all are considered disease causing. Of these 12 patients, 9 had PFH. This indicates a detection rate of 56% (9/16) in patients with PFH. We found 2 mutations (APP V717I) in 2 of the 3 the UFH-patients, and only 1 mutation (PrP T188K) in 1 of the 17 patients with NFH. No mutation was found in tau and neuroserpin genes. To date, three patients died and FAD, predicted by PS mutations in two patients, and prion disease, predicted by a PrP mutation in the third one, were histopathologically confirmed at autopsy. Up to now, mutation findings may be the most specific biomarkers for an ante mortem diagnosis of FAD or hereditary prion disease.

Genetic association of an alpha2-macroglobulin (Val1000lle) polymorphism and Alzheimer's disease

alpha2-Macroglobulin (A2M) is a proteinase inhibitor found in association with senile plaques (SP) in Alzheimer's disease (AD). A2M has been implicated biochemically in binding and degradation of the amyloid beta (Abeta) protein which accumulates in SP. We studied the relationship between Alzheimer's disease and a common A2M polymorphism, Val1000 (GTC)/Ile1000 (ATC), which occurs near the thiolester active site of the molecule. In an initial exploratory data set (90 controls and 171 Alzheimer's disease) we noted an increased frequency of the G/G genotype from 0.07 to 0.12. We therefore tested the hypothesis that the G/G genotype is over-represented in Alzheimer's disease in an additional independent data set: a group of 359 controls and 566 Alzheimer's disease patients. In the hypothesis testing cohort, the G/G genotype increased from 0.07 in controls to 0.12 in Alzheimer's disease (P < 0.05, Fisher's exact test). The odds ratio for Alzheimer's disease associated with the G/G genotype was 1.77 (1.16-2.70, P < 0.01) and in combination with APOE4 was 9.68 (95% CI 3.91-24.0, P < 0.001). The presence of the G allele was associated with an increase in Abeta burden in a small series. The A2M receptor, A2M-r/LRP, is a multifunctional receptor whose ligands include apolipoprotein E and the amyloid precursor protein. These four proteins have each been genetically linked to Alzheimer's disease, suggesting that they may participate in a common disease pathway.

[General automated documentation and performance data on the surgical intensive care unit--the theoretical concept of the Regensburg Surgical University Clinic]

Documentation is becoming an ever more time-consuming task due to the need to document increasing ICU productivity, quality management and cost-assessment data. Automatic charting of on-line monitoring data, therapeutic-device data, clinical laboratory data, microbiological data, radiological data and other data reduces documentation time significantly. One of the major advantages of PDMS in the SICU is the quality of the documentation and with better documentation the therapist is able to improve the quality of care. Not only the physician, but also nurses and physiotherapists are able to benefit from these advantages. Our concept, SURGIC (Department of Surgery, University Regensburg, Germany, Intensive Care), stands for: widely automated documentation, work orientation, including physicians, nurses' and physiotherapists' tasks, minimal dataset for simple use and perfect overview, costs assessments, scientific dataset, SICU PDMS as a part of the clinical information system, and professional support by a software-house is necessary.

A comparison of FDG PET and IQNB SPECT in normal subjects and in patients with dementia

Prior studies of patients with dementia have found similar qualitative patterns of cerebral glucose utilization with [18F]2-fluoro-2-deoxyglucose (FDG) PET and of putative muscarinic receptor activity with [123I]3-quinuclidinyl-4-iodobenzilate (IQNB). This raised doubts about whether receptor binding determines IQNB distribution and whether clinical information in IQNB scans is unique. To compare the methods directly, 4 normal volunteers and 7 patients with dementia underwent FDG PET and high-resolution IQNB SPECT scans. In normal subjects, relative regional activity from the paired scans was only weakly correlated (r = 0.29). Some regions (e.g., thalamus, frontal cortex) showed a clear disassociation of activity. In demented patients, IQNB scans tended to show larger defects than FDG scans, although one focal defect appeared only with PET. Results suggest that IQNB SPECT data are not primarily related to general physiological activity or regional cerebral blood flow and are not explained by attenuation or volume-averaging artifacts. Further studies should investigate whether IQNB scanning is a more sensitive in vivo measure of the extent of Alzheimer's disease than is FDG PET.