[Indications and results of endovascular therapy of critical limb ischemia]. / Indikationen und Ergebnisse der endovaskulären Therapie der kritischen Extremitätenischämie.

BACKGROUND: Critical limb ischemia (CLI) is the most severe form of peripheral artery occlusive disease and is characterized by high amputation, morbidity and mortality rates. Therefore, revascularization is the essential step in therapy for retention of the affected limb. OBJECTIVES: Although for a long time bypass surgery represented the gold standard in the treatment of CLI, in recent years there has been a disproportionate increase of endovascular treatment despite the lack of level-data. In this review the indications and results of endovascular therapy of CLI are presented on the basis of published data. METHODS: A literature search was carried out to identify publications that compared the results of endovascular and surgical therapy as well as observational studies about different endovascular techniques. RESULTS: The BASIL study provided the highest quality data comparing endovascular and surgical treatment of CLI. The long-term data of the BASIL trial showed that apart from patients with a suitable vein and a life expectancy of more than 2 years, first line endovascular therapy is equivalent to surgical treatment. The equivalence could also be demonstrated in a meta-analysis comparing operative and endovascular treatment of CLI. CONCLUSION: The CLI is a disease with high mortality and morbidity risks. Due to the comparable amputation-free survival times with lower complication rates in the published data, in most patients an endovascular first strategy in experienced centers can be justified.

MESNA (sodium 2-mercaptoethanesulfonate) for prevention of contrast medium-induced nephrotoxicity - controlled trial.

BACKGROUND: The purpose of this study was to examine the efficacy of sodium 2-mercaptoethanesulfonate (MESNA), a reactive oxygen scavenger, in at-risk patients given radiographic contrast agents. Contrast-induced nephropathy (CIN) is a common complication of radiographic procedures; reactive oxygen species (ROS) could play a key role. METHODS: We conducted a randomized, double-blinded, placebo-controlled trial in 100 patients with stable serum creatinine levels ≥ 150 µmol/l. They received an infusion of either 1,600 mg of MESNA (n = 51) or placebo (n = 49) plus 0.9% saline prior to and after contrast administration. CIN was defined as a ≥ 25% increase in serum creatinine after 48 h compared to baseline. RESULTS: CIN occurred in 7 patients in the placebo group and none in the MESNA group (p = 0.005). The adjusted odds ratio for CIN was 0.17 (95% confidence interval 0.03 - 0.80, p = 0.026) in the MESNA group compared to the placebo group. Cystatin C concentrations decreased slightly in the MESNA group but increased in the control group (p < 0.05). CONCLUSION: MESNA plus volume expansion before and during contrast exposure was effective in this single-center study for preventing CIN compared to volume expansion alone.

[Corneal topography. Analysis of the corneal surface]. / Korneale Topographie. Oberflächenanalyse der Hornhaut.

Various diagnostic procedures have been developed for analyzing the corneal surface. Corneal topographical measurements can be performed by classic Placido disc topographers and tomographers creating three-dimensional corneal models from cross-sectional images. Using a slit scanning system or the Scheimpflug technique additional information about the anterior segment can be obtained. New systems give us a wide range of diagnostic tools. Beside the measurement of the corneal anterior and posterior surfaces and point-to-point-pachymetry they enable analysis of corneal aberrations and measurement of the whole anterior segment, including the anterior chamber and the position of implants, pupil diameter, horizontal white-to-white and the kappa angle. Densitometry, statistical programs for the evaluation of corneal pathology and assistance with intraocular lens calculation following excimer laser treatment are further options available. This article is intended to give an overview of the principles and limitations of the various diagnostic systems.

Sliding multislice MRI for abdominal staging of rectal gastrointestinal stromal tumours.

Anorectal gastrointestinal stromal tumours (GISTs) are uncommon mesenchymal neoplasms. The objective of this report was to demonstrate the value of sliding multislice (SMS) as an upcoming method of continuously moving table MRI, providing detailed abdominal staging of rectal GISTs. Integration of SMS into a high-resolution pelvic MR imaging protocol allows for both detailed assessment of rectal GISTs and depiction of the entire abdomen with high image quality. The staging of liver, malignant lymph nodes and bone metastases is now possible, prolonging pelvic MRI for only one minute.

Why is the Plasmodium falciparum hexose transporter a promising new drug target?

Chemotherapy of malaria parasites is limited by established drug resistance and lack of novel treatment options. Intraerythrocytic stages of Plasmodium falciparum, the causative agent of severe malaria, are wholly dependent upon host glucose for energy. A facilitative hexose transporter (PfHT), encoded by a single-copy gene, mediates glucose uptake and is therefore an attractive potential target. The authors first established heterologous expression in Xenopus laevis to allow functional characterisation of PfHT. They then used this expression system to compare the interaction of substrates with PfHT and mammalian Gluts (hexose transporters) and identified important differences between host and parasite transporters. Certain Omethyl derivatives of glucose proved to be particularly useful discriminators between mammalian transporters and PfHT. The authors exploited this selectivity and synthesised an O-3 hexose derivative that potently inhibits PfHT expressed in oocytes. This O-3 derivative (compound 3361) also kills cultured P. falciparum with comparable potency. Compound 3361 acts with reasonable specificity against PfHT orthologues encoded by other parasites such as Plasmodium vivax, Plasmodium yoelii and Plasmodium knowlesi. Multiplication of Plasmodium berghei in a mouse model is also significantly impeded by this compound. These findings validate PfHT as a novel target.

Artemisinins target the SERCA of Plasmodium falciparum.

Artemisinins are extracted from sweet wormwood (Artemisia annua) and are the most potent antimalarials available, rapidly killing all asexual stages of Plasmodium falciparum. Artemisinins are sesquiterpene lactones widely used to treat multidrug-resistant malaria, a disease that annually claims 1 million lives. Despite extensive clinical and laboratory experience their molecular target is not yet identified. Activated artemisinins form adducts with a variety of biological macromolecules, including haem, translationally controlled tumour protein (TCTP) and other higher-molecular-weight proteins. Here we show that artemisinins, but not quinine or chloroquine, inhibit the SERCA orthologue (PfATP6) of Plasmodium falciparum in Xenopus oocytes with similar potency to thapsigargin (another sesquiterpene lactone and highly specific SERCA inhibitor). As predicted, thapsigargin also antagonizes the parasiticidal activity of artemisinin. Desoxyartemisinin lacks an endoperoxide bridge and is ineffective both as an inhibitor of PfATP6 and as an antimalarial. Chelation of iron by desferrioxamine abrogates the antiparasitic activity of artemisinins and correspondingly attenuates inhibition of PfATP6. Imaging of parasites with BODIPY-thapsigargin labels the cytosolic compartment and is competed by artemisinin. Fluorescent artemisinin labels parasites similarly and irreversibly in an Fe2+-dependent manner. These data provide compelling evidence that artemisinins act by inhibiting PfATP6 outside the food vacuole after activation by iron.

Inhibitory non-genomic effects of progesterone on Na+ absorption in epithelial cells from Xenopus kidney (A6).

The effect of the steroid hormone progesterone on transepithelial sodium transport was measured in confluent monolayers of the A6-cell line from Xenopus kidney. Apical permeabilization with Amphotericin B enabled us to measure the Na+/K+-pump current, and current-fluctuation analysis was used to analyze changes in apical channel density and gating characteristics. Basolateral progesterone (22.2 microM) had a rapid inhibitory effect on the Na+/K+-pump current, and a corresponding decrease in Na+ channel density. The effect occurred within some minutes and took about 50 min to reach a new steady state, in which 45% of the macroscopic current (ISC) was inhibited. Progesterone also inhibits the hypo-osmotic stimulation of Na+ channels which occurs in untreated monolayers. Compared with the known effects of adrenal steroids, our results show a rapid inhibitory action of a steroid hormone on Na+ absorption. The time profile of the progesterone effect suggests, at least in the first minutes, a non-genomic action of progesterone.

Silent BOLD imaging.

Pulsed magnetic field gradients in magnetic resonance imaging produce high levels of acoustic noise. In functional magnetic resonance imaging, acoustic scanner noise causes unwanted masking effects. Recently, we proposed a method to perform magnetic resonance imaging experiments undisturbed by acoustic scanner noise by utilizing the property of standard gradient coils to poorly submit acoustic noise in the low frequency range. The silent gradient scheme is now incorporated into a standard T(2)*-weighted sequence. Additionally, simultaneous multi-slice excitation (SIMEX) pulses were implemented to improve the intrinsic low volume coverage of the silent sequence. The proposed silent SIMEX technique was tested and compared with a standard noisy technique using auditory and visual stimulation paradigms. The scanner noise during the silent experiments could be reduced below the range of the ambient noise of the magnet room. This feasibility study shows a trend of decreased activated areas in the noisy experiment for both, the visual and auditory paradigm.

Facilitation of electric forepaw stimulation-induced somatosensory activation in rats by additional acoustic stimulation: an fMRI investigation.

The influence of scanner acoustic noise on somatosensory activation pattern in rat cortex was investigated by functional magnetic resonance imaging (fMRI) using the blood oxygenation level-dependent (BOLD) contrast. This was achieved by two approaches. The first approach was to compare a conventional, loud fMRI sequence with a new sequence, in which the noise level was reduced by about 30 dB. In the second approach, the inner ear of the animal was destroyed, resulting in deafness. We compared the activation patterns obtained with both sequences before and after cochleotomy. The activated area was larger when data were sampled with background noise, and was also larger before cochleotomy than after. Thus, facilitation of somatosensory activation is induced by additional acoustic stimulation. Magn Reson Med 44:317-321, 2000.

Inhibition of uptake, steady-state currents, and transient charge movements generated by the neuronal GABA transporter by various anticonvulsant drugs.

1. We have expressed the GABA transporter (GAT1) of mouse brain in Xenopus oocytes and have investigated the effects of four antiepileptic drugs, tiagabine (TGB), vigabatrin (VGB), gabapentin (GBP) and valproate (VAL), on GAT1 transporter function by measurements of 3H-labelled GABA uptake and GAT1-mediated currents. 2. Not only TGB, a well-known inhibitor of GAT1-mediated transport, but also the other drugs efficiently inhibit the uptake of [3H]-GABA by GAT1. Inhibition at 50% is obtained for VGB, TGB, GBP, and VAL at concentrations of about 1 nM, 1 microM, 50 microM and 100 microM, respectively. 3. However, GAT1-mediated steady-state and transient currents are nearly unaffected by VGB, GBP, and VAL at even five times higher concentrations. Only TGB blocks the uptake and steady-state and transient currents at micromolar concentrations. 4. VGB exhibits a complex interaction with GAT1; at concentrations about 1 nM, the inhibition of uptake is released, but at millimolar concentrations the uptake is inhibited again, and also the GAT1-mediated current is finally inhibited at these concentrations with a KI value of 0.5 mM. The concentration dependency of inhibition of uptake can be explained by two interaction sites with different affinities, a blocking site and a transport site. 5. The differences in effects of VAL, GBP, and VGB on uptake and currents can be attributed to the fact that GAT1 has the capability to operate in an electrogenic mode without uptake of GABA. We suggest that inhibition occurs only when GAT1 operates in the GABA-uptake mode. 6. The inhibition of GABA uptake by these four drugs will result in an elevation of the GABA concentration in the synaptic cleft, which will enhance synaptic inhibition and thereby contribute to their antiepileptic effects.

Effect of mutation of glycosylation sites on the Na+ dependence of steady-state and transient currents generated by the neuronal GABA transporter.

The GABA (gamma-aminobutyric acid) transporter (GAT1) belongs to a superfamily of secondary active uptake systems for neurotransmitters that depend on the electrochemical gradients for Na+ and Cl-. In the GAT1, two Na+ ions and one Cl- ion are co-transported with one GABA molecule. Steady-state transport activity and transient charge movements during partial reactions of the transport cycle of the GAT1 of mouse brain expressed in Xenopus oocytes were investigated by two-electrode voltage clamp. Functional expression was demonstrated by Na+-dependent [3H]GABA uptake. Effects of mutation of two out of three N-glycosylation sites located in the extracellular loop between transmembrane domains 3 and 4 (Asn176, Asn181, Asn184) were analysed. Simultaneous substitution of two Asn by Asp leaves the transport system intact but leads to a reduction in turnover and complex changes in the interaction of external Na+ with the transport protein. If Asn176 is mutated to Asp and simultaneously Asn181 to Gly, no transport and no charge movements can be detected. In conclusion, mutations of the glycosylation sites result in altered transport, and the local conformation at Asn181 is critical for expression of transport activity.

Sarcosine reductase of Tissierella creatinophila: purification and characterization of its components.

Sarcosine reductase is the only reductase system present in Tissierella creatinophila when grown on creatinine plus formate. The acetyl-phosphate-forming component protein C was purified to homogeneity. SDS-PAGE of the purified protein revealed two protein bands with apparent mol. masses of 62 and 50 kDa. The N-terminal amino acid sequence of the two subunits was determined. Antibodies raised against each of the subunits of protein C from Eubacterium acidaminophilum cross-reacted with the corresponding protein present in T. creatinophila, Clostridium litorale and Clostridium sporogenes. The arsenate-dependent hydrolysis of acetyl phosphate catalyzed by protein C was partly inhibited by antibodies directed against the large subunit. Antibodies raised against the small subunit were twice as effective, which indicates that this subunit is the primary site of acetyl transfer from acetyl phosphate. The protein A component of the sarcosine reductase of T. creatinophila was purified to homogeneity by cochromatography with thioredoxin reductase on DEAE-Sephacel, hydroxylapatite, Q-Sepharose, and Sephacryl 100-HR. Protein A had an apparent mol. mass of 21 kDa. Its N-terminal amino acid sequence showed high similarities to that of other proteins A. Initial steps for the purification and preliminary characterization of the sarcosine-specific, substrate-binding protein Bsarcosine component of T. creatinophila indicated the involvement of a 50-kDa protein.

Voltage-dependent inhibition of the Na+,K+ pump by tetraethylammonium.

Tetraethylammonium (TEA+) is an effective inhibitor of a variety of K+ channels, and has been widely used to reduce K+-sensitive background conductances in electrophysiological investigations of the Na+,K+-ATPase. Here we demonstrate by combination of two-electrode voltage clamp (TEVC) and giant patch clamp of Xenopus oocytes, and measurements of the activity of purified ATPase of pig kidney that TEA+ directly inhibits the Na+,K+-ATPase from the outside. The KI value in TEVC experiments at 0 mV is about 10 mM increasing with more negative potentials. A similar voltage-dependent inhibition by TEA+ was observed in the excised membrane patches except that the apparent KI value at 0 mV is about 100 mM, a value nearly identical to that found for inhibition of purified kidney ATPase. The voltage-dependent inhibition can be described by an effective valency of 0.39 and is attributed to an interference with the voltage-dependent binding of K+ at an external access channel. The apparent dielectric length of the access channel for K+ is not affected by TEA+.

[The pathogen spectrum of blood cultures of premature and newborn infants in a neonatal intensive care unit]. / Keimspektrum von Blutkulturen Früh- und Neugeborener einer neonatologischen Intensivstation.

The bacterial spectrum of blood cultures in a neonatal intensive-care unit was retrospectively assessed in a two-year study. Analysis of positive blood cultures showed a dominance of gram-positive bacteria, especially of coagulase-negative staphylococci. The resistance of these germs points to vancomycin as the most effective antibiotic. B-streptococci, germs that are dreaded especially in neonatology, were not found in any of the cases. Positive blood cultures were mostly in correlation with clinical symptoms, less so to the leukocyte count and/or C-reactive protein levels. There was no case of death directly caused by sepsis.

[Infections after bone marrow transplantation in childhood]. / Infektionen nach Knochenmarktransplantationen im Kindesalter.

In 66 children having undergone bone marrow transplantation (BMT) the occurrence of infections was studied retrospectively. Bacterial infections were mostly found in the early period after transplantation before marrow engraftment. The analysis of positive blood cultures showed a dominance of gram-positive bacteria, especially of coagulase-negative staphylococci. Cytomegalovirus (CMV) infections were most important, because of its high rate and the risk of CMV associated interstitial pneumonia (IP), two patients suffered from. Infections from herpes simplex virus (HSV), varizella zoster virus (VZV) and Epstein Barr virus (EBV) had no influence on prognosis. In fungal infections the systemic aspergillosis was the most important complication. To increase the effectiveness and safety of therapy the serum levels of antibiotics and antifungal drugs should be determined.

Hormonal control of RNA polymerases in rat bone marrow nuclei. The action of erythropoietin and testosterone.

The cytodifferentiation of stem cells to mature cells in bone marrow is an appropiate system to study biochemical aspects of hormonal action. We have used this system to analyze the way how erythropoietin and testosterone regulate erythropoiesis at the molecular level. Experiments designed to correlate the biochemical action of both hormones and to determine their differential action on rat bone marrow nuclei DNA-dependent RNA polymerases are reported. The effect of both hormones on the synthesis of RNA by isolated nuclei derived from normal rats was studied. Erythropoietin enhances the activity of RNA polymerase type II while testosterone stimulates polymerase type I activity. Gel-electrophoresis analysis of nuclear RNA shows that erythropoietin enhances the synthesis of RNA species with sedimentation coefficients of 30S, 22S, 15S, and 9S. Testosterone stimulates the synthesis of the 28 and 18S RNA as well as 4S RNA. A model is postulated to explain the action of erythropoietin and testosterone on RNA synthesis by isolated rat bone marrow nuclei.