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Biomedical subjects

C Nolte

Publications and source records attributed to C Nolte.

At least 19 recordsLinked to original sources
PubMed2005

Gender imbalance in living kidney donation in Switzerland.

Gender characteristics were analyzed in 631 living kidney donors followed by the Swiss Organ Living Donor Health Registry (SOL-DHR) from 1993 to 2003; 65% of kidney donors were women and 64% of recipients were men. The proportion remained stable over the years and in different donor age classes from 25 to 74 years. The observed rate of female life partners giving their kidneys to male life partners was significantly higher than expected (P < .005). After exclusion of spousal pairs, the observed rate of gender pairing in all 4 possible directions differed significantly from the expected rate (P < .0001). Men were always behind the expected rate for kidney donation and women ahead. The main 3 reasons for gender imbalance in living kidney donors in Switzerland are the higher risk of men to acquire end-stage renal failure, financial risks for main breadwinners and the traditional female role in family life. Measures are proposed to narrow the gap between expected and observed gender balance in living organ donation.

Adult↗
PubMed2005

[The Swiss Organ Living Donor Health Registry (SOL-DHR)].

The Swiss Organ Living Donor Health Registry (SOL-DHR) started in April 1993. The purpose was the prospective and sequential follow up of donors long-term health. Between 1993 and January 2005 737 Living Kidney donations were registered and followed. Two thirds of donors were female and two thirds of recipients male. The three most common relations were life-partners, parents and siblings (approximately 30% each). 10% of donors could not be followed since living far abroad and 5% were lost due to missing current address after moving. 9 donors died (4 malignancies, 2 traffic accidents, 1 myocardial infarction, 1 stroke and 1 suicide), non due to kidney donation. Perioperative complications were age dependent, ranging from 17% in donors below the age of 40 year and 46% in donors older than 70 years. The longterm complications were divided in surgical, medical and psychological ones. The most common surgical long-term complications were pain (cicatrice, back, abdomen) and hernias. The major medical complications were hypertension (35% at seven years after donation) and rising rate of Albuminuria (9% at seven years). Although hypertension was not higher than in an age matched Swiss control population, untreated hypertension was regarded as the higher risk for development of glomerulosclerosis than in people with two kidneys. No donor went into end stage renal failure. Using the SF-8-Test to quantify the psychological well-being the mean MCS (mental component summary) was 54.3 +/- 7.8 as compared to 52.9 +/- 7.7 in the age matched control population. MCS was low (< 40) in 6.2% and very low (< 25) in 2.2% of donors. 94.4 % of donors would donate again, while 4.3% would not (mostly women). The reasons not to donate again was mainly related to poor outcome of the kidney recipient, or long-lasting major pain or disappointment about medical handling before (not enough information, wrong advice) and after organ donation. The association of Swiss Living Organ Donors, where only kidney or liver donors can become a member, are organising self-help-groups for pain, psychological and financial problems (with health insurances). The organisation and financial support of SOL-DHR is briefly described. The waste majority of living kidney donors are very satisfied about the free care given by SOL-DHR.

Humans↗
PubMed2005

Abundance, dispersion and parasitism of the stem borer Busseola fusca (Lepidoptera: Noctuidae) in maize in the humid forest zone of southern Cameroon.

This study was conducted in the humid forest zone of Cameroon, in 2002 and 2003. The main objective was to investigate the effects of intercropping on infestation levels and parasitism of the noctuid maize stem borer Busseola fusca Fuller. Two trials were planted per year, one during the long and one during the short rainy season. Maize monocrops were compared with maize/legume or maize/cassava intercrops in two spatial arrangements: maize on alternate hills or in alternate rows. Spatial analyses showed that the stemborer egg batches were regularly dispersed in the maize monocrop and aggregated in the intercrops, as indicated by b, the index of dispersion of Taylor's power law. Depending on the crop association and planting pattern, intercrops reduced the percentage of plants with stem borer eggs by 47.4-58.4% and egg densities by 41.2-54.5% compared to monocropped maize. Consequently, larval densities were 44.4-61.5% lower in intercrops compared to monocrops. Intercropping maize with non-host plants did not affect larval parasitism. Up to two-fold higher levels of egg parasitism by scelionid Telenomus spp. were recorded in inter- compared to monocrops during the short rainy seasons of 2002 and 2003. No differences were found among the mixed cropping treatments and parasitism was lower during the long compared to the short rainy seasons. It was proposed that differences in levels of parasitism were due to density dependence effects rather than the effect of the presence of non-host plants in the system.

Agriculture↗
PubMed2005

Relationships of intercropped maize, stem borer damage to maize yield and land-use efficiency in the humid forest of Cameroon.

Stem borers are the most important maize pests in the humid forest zone of Cameroon. Field trials were conducted in the long and short rainy seasons of 2002 and 2003 to assess the level of damage and yield reductions caused by stem borers in monocropped maize and in maize intercropped with non-host plants such as cassava, cowpea and soybean. The intercrops were planted in two spatial arrangements, i.e. alternating hills or alternating rows. All intercrops and the maize monocrop were grown with and without insecticide treatment for assessment of maize yield loss due to borer attacks. The land-use efficiency of each mixed cropping system was evaluated by comparing it with the monocrop. The temporal fluctuation of larval infestations followed the same pattern in all cropping systems, but at the early stage of plant growth, larval densities were 21.3-48.1% higher in the monocrops than in intercrops, and they tended to be higher in alternating rows than alternating hills arrangements. At harvest, however, pest densities did not significantly vary between treatments. Maize monocrops had 3.0-8.8 times more stems tunnelled and 1.3-3.1 times more cob damage than intercrops. Each percentage increase in stem tunnelling lowered maize grain yield by 1.10 and 1.84 g per plant, respectively, during the long and short rainy season in 2002, and by 5.39 and 1.41 g per plant, respectively, in 2003. Maize yield losses due to stem borer were 1.8-3.0 times higher in monocrops than in intercrops. Intercrops had generally a higher land-use efficiency than monocrops, as indicated by land-equivalent-ratios and area-time-equivalent-ratios of >1.0. Land-use efficiency was similar in both spatial arrangements. At current price levels, the net production of mixed cropping systems was economically superior to controlling stem borers with insecticide in monocropped maize. The maize-cassava intercrop yielded the highest land equivalent ratios and the highest replacement value of the intercrop. At medium intensity cropping this system is thus recommended for land-constrained poor farmers who do not use external inputs such as fertilizer and insecticides.

Agriculture↗
PubMed2003

Effect of incomplete (spontaneous and postthrombolytic) recanalization after middle cerebral artery occlusion: a magnetic resonance imaging study.

BACKGROUND AND PURPOSE: Early reperfusion is one of the best predictors of good outcome after acute middle cerebral artery (MCA) occlusion. The purpose of this study was to analyze the frequency and relevance of incomplete recanalization for tissue and clinical outcome. METHODS: From a larger acute stroke database (Kompetenznetzwerk Schlaganfall B5), all patients (n=82) with MCA main stem occlusion (excluding carotid T-occlusions) were selected. These patients had received a multiparametric stroke MRI protocol including diffusion- and perfusion-weighted imaging (DWI, PWI) and MR angiography (MRA) within 6 hours after symptom onset, at day 1 and after 1 week. Recanalization status was determined with MRA on day 1 (according to Thrombolysis In Myocardial Infarction flow grades) and used to group patients into those with persistent occlusion (0) or minimal (1), partial (2), or complete (3) recanalization. RESULTS: Incomplete recanalization according to MRI criteria was found in 39 patients (grade 1: n=20; grade 2: n=19), complete recanalization in 10, and persistent occlusion in 33. There was no statistically significant difference in any of the clinical (National Institutes of Health Stroke Scale score) or MRI baseline parameters (DWI lesion, PWI deficit, mismatch volume, mismatch ratio). However, lesion growth was smaller in patients with recanalization (even in patients with only minimal recanalization) and outcome was related to the degree of recanalization (mean modified Rankin score at 90 days: 3.36, 2.70, 1.79, and 1.44 for the groups with no, minimal, partial, and complete recanalization, respectively). Both incomplete and complete recanalization was more frequent in patients receiving thrombolysis. CONCLUSIONS: Incomplete recanalization on day 1 is a frequent MR finding after MCA main stem occlusion, indicating a more favorable clinical course than persistent occlusion. MR indicators of early recanalization could be useful surrogates of efficacy in thrombolytic trials.

Adult↗
PubMed2001

GFAP promoter-controlled EGFP-expressing transgenic mice: a tool to visualize astrocytes and astrogliosis in living brain tissue.

We have generated transgenic mice in which astrocytes are labeled by the enhanced green fluorescent protein (EGFP) under the control of the human glial fibrillary acidic protein (GFAP) promoter. In all regions of the CNS, such as cortex, cerebellum, striatum, corpus callosum, hippocampus, retina, and spinal cord, EGFP-positive cells with morphological properties of astrocytes could be readily visualized by direct fluorescence microscopy in living brain slices or whole mounts. Also in the PNS, nonmyelinating Schwann cells from the sciatic nerve could be identified by their bright green fluorescence. Highest EGFP expression was found in the cerebellum. Already in acutely prepared whole brain, the cerebellum appeared green-yellowish under normal daylight. Colabeling with GFAP antibodies revealed an overlap with EGFP in the majority of cells. Some brain areas, however, such as retina or hypothalamus, showed only low levels of EGFP expression, although the astrocytes were rich in GFAP. In contrast, some areas that were poor in immunoreactive GFAP were conspicuous for their EGFP expression. Applying the patch clamp technique in brain slices, EGFP-positive cells exhibited two types of membrane properties, a passive membrane conductance as described for astrocytes and voltage-gated channels as described for glial precursor cells. Electron microscopical investigation of ultrastructural properties revealed EGFP-positive cells enwrapping synapses by their fine membrane processes. EGFP-positive cells were negative for oligodendrocyte (MAG) and neuronal markers (NeuN). As response to injury, i.e., by cortical stab wounds, enhanced levels of EGFP expression delineated the lesion site and could thus be used as a live marker for pathology.

Animals↗
PubMed2000

Extracellular acidification decreases the basal motility of cultured mouse microglia via the rearrangement of the actin cytoskeleton.

The present study was undertaken to examine the effect of extracellular pH (pH(0)) on the locomotor function of murine microglial cells in vitro. We have found that basal motility of microglia, as measured by a computer-assisted video assay, decreased in an acidic, but not in an alkaline environment. Extracellular acidification affected the architecture of F-actin cytoskeleton, inducing bundling of actin and the formation of stress fibers. The change in intracellular pH (pH(i)) resulting from the change in pH(0) seems to be a prerequisite for the motility decrease since other means to decrease pH(i), namely Na(+)-free solution (in the absence of HCO(-)(3)) and nigericin-containing solution, mimicked the extracellular acidification. In contrast to its pronounced effect on basal motility of microglial cells, the motility increase, as induced by the chemoattractant complement 5a (C5a), was not affected by the acidic environment. The relationship of pH(0) to the locomotor function was also studied in a long-term microchemotaxis assay where microglia migrated within a pH gradient. Intracellular acidification induced by lowering pH(0) to 6.0 or removal of Na(+) from the assay medium decreased basal microglial cell migration. The C5a-induced chemotactic migration was moderately decreased by the acidic environment. In conclusion, our results suggest that acidification of the microglial extracellular milieu leads to a decrease in pH(i) and thereby reduces the basal microglial motility and C5a-induced chemotaxis via a rearrangement of the cytoskeleton. We would therefore like to speculate that changes in pH(i) constitute an important control mechanism in regulating the locomotor function of microglia in culture and probably also in the intact tissue.

Acids↗
PubMed2000

Ammonium triggers calcium elevation in cultured mouse microglial cells by initiating Ca(2+) release from thapsigargin-sensitive intracellular stores.

Microglial cells are thought to serve as sensors for pathologic events in the brain. In the present study we demonstrate that these cells respond with an increase in intracellular calcium concentration ([Ca2+]i) to intracellular alkaline shifts induced by either application of NH3/NH4+ or by an extracellular alkaline shift. The cytoplasmic pH (pHi) and [Ca2+]i in cultured mouse microglial cells were studied employing the fluorescent probes BCECF and fura-2, respectively. Application of NH3/NH4+ caused an initial rapid alkalinization followed by a slow recovery towards the resting level, while application of alkaline (pH 8.2) solution triggered a slower rise in pHi. The [Ca2+]i elevation triggered by NH3/NH4+ and extracellular alkaline shift were caused by different mechanisms: extracellular alkalinization induced a transmembrane Ca2+ entry, whereas NH3/NH4+ triggered Ca2+ release from thapsigargin- and ATP-sensitive intracellular pools. The mobilization of intracellular Ca2+ caused by NH3/NH4+ was blocked by a specific inhibitor of phospholipase C, U-73122, but was not affected by an inhibitor of G-protein, pertussis toxin. This implies that NH3/NH4 interacts with phospholipase C and leads to an increase in the intracellular level of inositol 1,4,5-trisphosphate (InsP3). In contrast to a previous study using a microglial cell line, application of NH3/NH4+ did not result in a release of tumor necrosis factor alpha (TNF-alpha), a marker of microglial activation, in the primary microglial cells. This implies that ammonium does not lead to activation of microglia in the culture model.

Adenosine Triphosphate↗
PubMed2000

Electrophysiological properties of microglial cells in normal and pathologic rat brain slices.

UNLABELLED: Microglial cells serve as pathologic sensors of the brain. They are highly abundant in all regions of the central nervous system (CNS) and are characterized by a ramified morphology within the normal tissue. In the present study, we have developed a procedure to study the membrane properties of identified, in situ microglia in acutely isolated brain slices from rat cortex, striatum and facial nucleus. Unlike the well characterized cultured microglial cells, ramified microglia of the slice are characterized by little, if any, voltage-gated membrane currents and a very low membrane potential. They are thus distinct from neurons, other glial cells and nonbrain macrophages. To study the consequences of microglial activation on the membrane channel pattern, we compared cells in the normal facial nucleus and at defined times after facial nerve axotomy. Within 12 h of axotomy, microglial cells expressed a prominent inward rectifier current and thus acquired the physiological properties of cultured microglia. Within 24 h of the lesion, the cells expressed an additional outward current, which is typical for lipopolysaccharide (LPS)-activated microglia in vitro. Seven days after the lesion, at a time of major regenerative processes in the facial nucleus, the physiological properties of microglial cells had reverted to those present prior to the pathological event. IN CONCLUSION: (i) ramified microglial cells represent a physiologically unique population of cells in the brain; (ii) are distinct from their cultured counterparts; and (iii), undergo a defined pattern of physiological states in the course of pathologic events.

Animals↗
PubMed2000

Phagocytic clearance of apoptotic neurons by Microglia/Brain macrophages in vitro: involvement of lectin-, integrin-, and phosphatidylserine-mediated recognition.

Microglia, the tissue macrophages of the brain, play a crucial role in recognition and phagocytic removal of apoptotic neurons. The microglial receptors for recognition of apoptotic neurons are not yet characterized. Here we established a co-culture model of primary microglia and cerebellar granule neurons to examine the receptor systems involved in recognition/uptake of apoptotic neurons. Treatment with 100 microM S-nitrosocysteine induced apoptosis of cerebellar neurons as indicated by nuclear condensation and phosphatidylserine exposure to the exoplasmic leaflet of the plasma membrane. Microglial cells were added to neurons 2 h after apoptosis induction and co-cultured for 6 h in the presence of ligands that inhibit recognition by binding to respective receptors. Binding/phagocytosis was determined after combined 4', 6-diamidino-2-phenylindole/propidium iodide (for apoptotic/necrotic neurons) and lectin staining (for microglia). Uptake of apoptotic neurons was reduced by N-acetylglucosamine or galactose, suggesting that recognition involves asialoglycoprotein-like lectins. Furthermore, the inhibition of microglial binding/uptake of apoptotic neurons by RGDS peptide suggests a role of microglial vitronectin receptor. As microglia selectively bind lipid vesicles enriched in phosphatidylserine and O-phospho-L-serine interfered with the uptake of apoptotic neurons, an involvement of phosphatidylserine receptor is rather likely. Apoptotic neurons do not release soluble signals that serve to attract or activate microglia. Collectively, these results suggest that apoptotic neurons generate a complex surface signal recognized by different receptor systems on microglia.

Animals↗
PubMed1999

[Transesophageal imaging of a coronary fistula in simultaneous endocarditis lenta].

A 61 year old diabetic patient with bacterial endocarditis probably caused by a congenital coronary fistula is presented. The fistula was already detected by transthoracic echocardiography. Transesophageal color-Doppler echocardiography identified the precise localization and course of the fistula. Additionally, in some parts of the fistula echogenic material could be seen that decreased in size after antibiotic treatment. Therefore, it was considered as corresponding to bacterial vegetations. Coronary angiography disclosed an ectopic aneurysmatic and elongated circumflex coronary artery. Thus, even in rare conditions such as coronary fistulas transesophageal echocardiography may be helpful to allow detection of morphological substrate of associated infective endocarditis.

Coronary Thrombosis↗
PubMed1999

Immunolocalization of the neural cell adhesion molecule L1 in epithelia of rodents.

The expression of the neural cell adhesion molecule L1 was analyzed in several non-neural tissues of the mouse using immunohistochemical and immunochemical techniques. In the adult mouse, L1 immunoreactivity was detectable in the basal and intermediate layers of epidermal and lingual epithelia, in the outer sheath of hair roots and in the single-layered endodermal epithelia of lung, small intestine, and colon. Epithelia of salivary glands also showed L1 immunoreactivity, while endothelial cells of blood vessels did not express detectable levels of L1. The epithelia of the kidney showed expression only in the collecting tubule system. In single-layered kidney epithelia and stratified epithelia, L1 expression was confined to lateral cell contacts and basal infoldings of the epithelial cells but was absent from apical and basal cell surface membranes. Also, in cultured keratinocytes L1 was confined to cell-cell contacts. During development of the epidermis, L1 immunoreactivity was first detectable at the onset of keratinization around embryonic day 16. At this age LI was detectable in the kidney on branching tubules of the ureter. Western blot analysis showed that L1 immunoreactivity in epidermis and kidney appeared as two bands of 190-210 and 210-230 kDa. Northern blot analysis of mRNA from the L1-immunopositive HEL-30 keratinocyte cell line revealed a single band with the expected size of 6 kb. The presence of L1 in epithelia indicates that this molecule may be involved in interactions between epithelial cells and thereby may affect differentiation and maintenance of epithelial tissues.

Animals↗
PubMed1998

Characterization of the pulse signal over the human head by near infrared spectroscopy.

In this study we examine and describe the changes in the hemoglobin oxygenation and the Cytochrome-C-Oxidase redox state that are caused by the pulsatile character of the blood flow in the human head. We used near-infrared spectroscopy (NIRS) in combination with simultaneously recorded ECG and Transcranial Doppler sonography of arteries and veins and show that there is a distinct time lag between heart activity, arterial blood flow, hemoglobin concentration as measured by NIRS and venous blood flow. NIRS has intensively been used to measure functional activation of the brain. When measuring cortical activation by functional stimulation, the pulse signal interferes with the acquired activation signal. We demonstrate that a filter algorithm can remove the pulse artifact and therefore improves the data acquired during visual stimulation.

Adult↗
PubMed1998

Tuberculin skin test conversion rates in New York City Emergency Medical Service health care workers.

OBJECTIVE: To determine annual tuberculin skin test conversion (infection) rates for prehospital health care workers (EMTs and paramedics) in an urban environment with a high prevalence of Mycobacterium tuberculosis. METHODS: We conducted a prospective study of prehospital health care workers for the New York City EMS, EMS Employee Health Service, and the Fire Department Bureau of Health Service to determine the tuberculin skin test conversion rates. In 1992, all current and new EMS prehospital health care workers without a known history of a positive tuberculin reaction received a baseline tuberculin purified protein derivative (PPD) skin test. Thereafter, (January 1, 1993-December 31, 1996) all EMS health care workers who had negative PPD skin test results received annual tuberculin PPD skin tests. Tuberculin skin test conversion was defined as induration of 10 mm or greater in a worker with a documented prior negative test result. The PPD skin test reaction was measured by trained professional readers. RESULTS: A total of 7,290 PPD test results were read during this study. Compliance with annual testing was 75%. Annual tuberculin skin test conversion rates were 1.3% in 1993, .7% in 1994, .1% in 1995, and .2% in 1996 (average .5%). In a static subgroup with at least 15 years' seniority, compliance with annual testing was 100% and annual tuberculin skin test conversion rates were .5% in 1993, 0 in 1994, .5% in 1995, and 1.5% in 1996 (average .6%). CONCLUSION: Despite the high prevalence of M tuberculosis infection in New York City and the potential for difficulty in the use of respiratory precautions during emergency response operations, EMS prehospital health care workers have an annual tuberculin conversion rate that is relatively low compared with hospital-based health care workers.

Cohort Studies↗
PubMed1998

Determination of the wavelength dependence of the differential pathlength factor from near-infrared pulse signals.

For the calculation of changes in oxyhaemoglobin, deoxyhaemoglobin and the redox state of cytochrome-c-oxidase from attenuation data via a modified Beer-Lambert equation the wavelength dependence of the differential pathlength factor (DPF(lambda)) has to be taken into account. The DPF, i.e. the ratio of the mean optical pathlength and the physical light source-detector separation at each wavelength, determines the crosstalk between the different concentrations and is therefore essential for a sensitive detection of chromophore changes. Here a simple method is suggested to estimate the wavelength dependence of the DPF(lambda) from pulse-induced attenuation changes measured on the head of adult humans. The essence is that the DPF is the ratio of the attenuation changes over absorption coefficient changes, and that the spectral form of the pulse correlated absorption coefficient change can be assumed to be proportional to the extinction coefficient of blood. Indicators for the validity of the DPF(lambda) derived for wavelengths between 700 and 970 nm are the stability of the calculated haemoglobin and cytochrome signals with variations of the wavelength range included for their calculation and its overall agreement with the data available from the literature.

Adult↗